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Vector Control and Dynamics of AC Drive
... The indirect field oriented control (IFOC) [26] is employed as a control scheme for the induction motor drive. A control block diagram is shown in Figure 3. ...
... The inner control loop regulates the direct (i sd ) and quadrature (i sq ) stator currents components [26]. The direct current control loop employs a proportional-integral (PI) controller with gains k pd and k id , which regulates the current i sd , which creates the rotor magnetic flux (λ dr ), thus indirectly regulating it for a settled reference. ...
... where R s is the stator resistance, and L s is the stator transient inductance, given by [26]: ...
In recent years, medium-voltage variable-speed drives have become popular in the industry. However, in some applications, the use of long cables can lead to overvoltages at the motor terminals, affecting the motor lifespan. Under such conditions, the use of passive filters is recommended. However, the use of inductive capacitive (LC) filters results in resonances, leading to control stability issues. This issue can be mitigated by introducing a resonance damping strategy. In this work, four damping strategies are implemented and designed: Passive damping, capacitor current feedback, capacitor voltage feedback, and notch filter-based damping. The paper performs a comparative study on the current control phase margin, current and voltage harmonic spectra, and overall changes in the control structure. Then, the effect of the damping strategy on the VSD control is evaluated, creating guidelines to support the selection of the appropriate damping strategy. The results indicate that capacitor voltage feedback stands out, since this strategy presents an interesting dynamic behavior while allowing the elimination of the passive damping losses at a relatively low cost.
... It is assumed that the induction machine used in the belt starter/generator servo drive is current/torque controlled by means of an embedded power conv verter) equipped with phase current sensors and a field-oriented (vector) contro [48]. Moreover, it is assumed that the embedded current/torque controller is tun well-damped and fast reference step response [49]. ...
... For more detailed insight into the alternating current machine control system and power converter control, the reader is kindly referred to references [35,[47][48][49] ...
... It is assumed that the induction machine used in the belt starter/generator electrical servo drive is current/torque controlled by means of an embedded power converter (inverter) equipped with phase current sensors and a field-oriented (vector) control system [48]. Moreover, it is assumed that the embedded current/torque controller is tuned for a well-damped and fast reference step response [49]. ...
In order to meet the increasingly stricter emissions’ regulations, road vehicles require additional technologies aimed at the reduction of emissions from the internal combustion engine (ICE). A favorable solution from the standpoint of costs and simplicity of integration is a 48-V electrical architecture utilizing a low-voltage/high-power induction machine, which operates as the so-called engine belt starter generator (BSG) coupled via a timing belt with the ICE crankshaft within a P0 mild hybrid power train and used for starting up and boosting of the ICE power output, as well as for recuperating kinetic energy during vehicle deceleration. The aim of this work was to design a vibration damping system for the belt transmission within the so-called front end accessory drive (FEAD), which couples the BSG with the ICE crankshaft and to test the control system by means of simulations for realistic operating regimes of the P0 mild hybrid power train in order to show the functionality of the proposed approach in terms of mild hybrid vehicle performance improvement. Simulation results have pointed out effective attenuation of belt compliance-related vibrations using the proposed active damping control, with vibration magnitude reduced between three and five times compared to the default case during engine start-up phase. They have indicated the realistic belt slippage effects during engine start-up phase and have illustrated the effectiveness of the FEAD torque boosting capability with 30% gain in acceleration during vehicle launch.
... T HE main control methods for drive systems are the field oriented control (FOC) [1], and direct torque control (DTC) [2]. The former employs linear controllers to generate the modulating signal which is subsequently fed into an explicit modulator stage. ...
... Hence, as demonstrated in this paper, the proposed implementation allows for a high granularity of switching, which, in turn, results in favorable system performance. 1 This paper is structured as follows. Section II introduces the mathematical model of the case study used in this paper. ...
... Based on the above, the mathematical model of the chosen case study is derived in the sequel. 1 Some preliminary results are presented in [14], [23]. ...
This paper deals with the real-time implementation of a long-horizon finite control set model predictive control (FCS-MPC) algorithm on an embedded system. The targeted application is a medium-voltage drive system which means that operation at a very low switching frequency is needed so that the switching power losses are kept relatively low. However, a small sampling interval is required to achieve a fine granularity of switching, and thus ensure superior system performance. This renders the real-time implementation of the controller challenging. To facilitate this, a high level synthesis (HLS) tool, which synthesizes C++ code into VHDL, is employed to enable a higher level of abstraction and faster prototype development of the real-time solver of the long-horizon FCS-MPC problem, namely the sphere decoder. Experimental results based on a small-scale prototype, consisting of a three-level neutral point clamped (NPC) inverter and an induction machine, confirm that the algorithm can be executed in real time within the targeted control period of 25us.
... Previously, the use of motors in industrial applications that required good performance in position and speed control were limited to DC machines. Such use was due to the inherent decoupling characteristics of the machine: one electrical circuit to impose magnetic flux on the machine (field) and another to impose torque (power), which simplifies the control of torque, position, and speed of the machine [5]. ...
... One difficulty of its use for position or speed control is its complex mathematical modeling, requiring greater computational effort for its implementation [5]. In addition, in induction machines there is no unique physical circuit for the field, and this makes its control more complex [13,14]. ...
... The experimental bench is composed of: There are two basic types of inverters, Voltage Source Inverter (VSI), powered by a voltage source, and Current Source Inverters (CSI) powered by a current source. VSI topology is more common and synthesizes a well-defined voltage in the machine terminals while CSI provides a current signal in the machine terminals [5]. Figure 2 presents the simplified schematic diagram of a VSI. ...
Induction machines are widely used in the industry due to their many advantages compared to other industrial machines. This article presents the study and implementation of speed control applied to a Three-phase Induction Machine (MIT) of the squirrel cage type. The induction motor was modeled using the rotor flux in the synchronous reference to design Proportional-Integral (PI) type controllers for the current and velocity control loops. It is the objective of the article also to present in detail the development of converter hardware that comprises the stages of power, acquisition, and conditioning of engine signals. The system was simulated using computational tools and validated using a prototype designed, constructed, and commissioned.
... where V m is the maximum voltage applied to the polar voltages V an , V bn , and V cn , which are directly connected to the motor; V DC Link and MI are the inverter voltage and maximum PWM modulation index, respectively. MI [28,29] can be calculated as follows: ...
... where ψ a is the value of flux linkage due to the permanent magnet and armature reaction. The i d and I q values before the base speed as an MTPA control [28] are as follows: ...
... Figs. 12 and 13 show the battery current map and efficiency map, respectively. The operation of the 12 V brake motor, which is the initial model, is largely divided into an MPTA [28] operating point P1 that operates as a normal brake and an FW [24] operating point P2 that operates as a quick brake. P1 is selected as the normal brake operating point (2 Nm, 1000 rpm) and P2 is selected as the quick brake operating point (2 Nm, 3500 rpm). ...
In this study, to maximise the performance and efficiency of 48 V integrated electric brake (IEB) system, a system‐level optimal design process is proposed for inverter‐driven brushless AC (BLAC) motor, taking into account the available input voltage that varies depending on the motor operating conditions. To get available input voltages, the voltage drops of battery wiring and inverter are reversely calculated from the motor output power. In the optimal design process, the resistance components in the inverter are separated into DC and AC parts, and these are analysed by including the dq equivalent circuit for motor analysis. The battery currents are obtained using the calculated maximum output performance and the loss between the battery and inverter. The proposed design process is applied to the optimal design of the 48 V motor for IEB systems. Also, to reduce the development cost of the 48 V motor, the manufacturing tools of the previously developed 12 V motor are shared. As an optimal design results, it is confirmed that there is an efficiency improvement effect of ∼5% compared to the conventional design of 12–48 V BLAC motor.
... A. Control of the RSC Fig. 3 shows the overall vector control scheme of the RSC, in which the independent control of the stator active power Ps and reactive power Qs is achieved by means of rotor current regulation in a stator-flux oriented synchronously rotating reference frame [11]. Therefore, the overall RSC control scheme consists of two cascaded control loops. ...
... The reference signals of the outer-loop power controllers are generated by the high-layer WFSC. voltage Vdc and the reactive power Qg exchanged between the GSC and the grid is achieved by means of current regulation in a synchronously rotating reference frame [11]. Again, the overall GSC control scheme consists of two cascaded control loops. ...
... Pei,max = Pmi,max -PLi = Psi,max + Pri,max (5) where PLi is the total power losses of WTG i, which can be estimated by the method in [9]; Psi,max and Pri,max are the maximum DFIG stator and rotor active powers of WTG i, respectively. In terms of the instantaneous variables in Fig. 1, the stator active power Ps can be written in a synchronously rotating d-q reference frame [11] as follows. ...
Wind turbine generators (WTGs) are usually controlled to generate maximum electrical power from wind under normal wind conditions. With the increasing penetration of wind power into electric power grids, energy storage devices will be required to dynamically match the intermittency of wind energy. To meet the requirements of frequency and active power regulation, energy storage devices will be required to dynamically match the intermittency of wind energy. A novel twolayer constant-power control scheme for a wind farm equipped with doubly-fed induction generator (DFIG) wind turbines. Each DFIG wind turbine is equipped with a supercapacitor energy storage system (ESS) and is controlled by the low-layer WTG controllers and coordinated by a high-layer wind-farm supervisory controller (WFSC). The WFSC generates the active-power references for the low-layer WTG controllers according to the active-power demand from the grid operator; the low-layer WTG controllers then regulate each DFIG wind turbine to generate the desired amount of active power, where the deviations between the available wind energy input and desired active power output are compensated by the ESS. Simulation studies are carried out in PSCAD/EMTDC on a wind farm equipped with 15 DFIG wind turbines to verify the effectiveness of the proposed control scheme.
... A standard field-weakening approach lies in adjusting the flux vector module inversely to angular speed [3] - [6]. Such control method has several disadvantages, the main of which are torque-producing current is overvaulted and inverter is not used to the full extent in terms of voltage and current. ...
... Similarly to field-weakening systems for DC machines, solutions have been proposed in which (estimated) EMF controller is implemented instead of the (estimated) flux vector module controller [3] - [6]. The classic closed-loop method has PI-voltage controller which generates a reference flux trajectory [2], [12] - [16]. ...
The torque and flux direct field-oriented control systems of induction motors based on the proposed open-loop and closed-loop field-weakening methods are presented. Field-weakening operation regimes are designed to take into account physical limitations of the motor and inverter. The developed solutions guarantee torque-flux reference trajectories tracking in all speed regulation regions of induction electric drive: constant torque, constant power and constant slip frequency. Tracking of torque and rotor flux vector module is ensured by special simultaneous generation of the torque and flux reference functions. The closed-loop method has an additional non-linear feedback channel of inverter voltage module which adjusts the flux reference based on the measured (estimated) stator voltage module in order to maintain it at the maximum level. It is shown by simulations that the closed-loop algorithm with a voltage controller provides more complete utilization of motor power compared to the open-loop method. It increases the dynamic power in the supply voltage limitation conditions. The proposed control systems have the typical structure of the modern vector-controlled induction drives and can be used to improve dynamic properties and efficiency in the field-weakening operation mode.
... According to the rotor characteristics, this negative-sequence current also depends on the IM load. The third term of (7) greatly depend on the IM load, but its magnitude is usually very small, since the negative-sequence voltage is generally much lower than the positive-sequence voltage [18]. Fig. 1 shows the test bench we used to test a 5.5 kW IM. ...
... The amplitude of the 100 Hz frequency components depends on the negative-sequence currents on the IM. The negative-sequence currents depend on the characteristics of the IM, the voltage unbalance, and the loading level of the IM [18] [19]. Fig. 4 shows that the amplitude of the 100 Hz frequency component grows linearly with the voltage unbalance. ...
... According to [23], the electromagnetic torque of electric motors is derived from the power flow. In the d-q system, the input complex power of PMSM can be derived based on the input and as ...
... Then, the reactive torque reference could be * = 2 3 2 * 2 (23) 2) If the stator flux linkage reference is set as � � * , the reactive torque reference can be derived based on (2), (3), and (18) ...
Deadbeat-direct torque and flux control (DB-DTFC) significantly improves the torque response performance compared with the conventional direct torque control. However, the existing DB-DTFC algorithm suffers from a relatively heavy computational burden due to its intricate derivation. Thus, two simplified DB-DTFC algorithms for permanent magnet synchronous machines (PMSMs) are proposed in this article to relieve the burden. The first one is based on the stator flux differential, and the second one is based on the complex power of PMSM. Furthermore, the performance of DB-DTFC highly relies on the accuracy of machine parameters. Thus, modified stator flux observer and electromagnetic torque observer are designed to enhance parameter robustness based on disturbance observer theory. The theoretical derivation of the proposed methods is investigated in-depth. Finally, both simulation and experimental results verify that the proposed deadbeat methods can maintain the deadbeat performances with a reduced computational burden. Meanwhile, the modified observer can help the deadbeat algorithms work well when machine parameters change.
... A simple equation for induced (or back-emf) voltage can be obtained from modified equivalent IM's circuit [1] : U i ϭ j s L m I m (evident DC machine analogy). It is obvious that the quotient U i / s should be kept constant because this will keep the amplitude of I m constant, too. ...
... The equivalent rotor magnetising current i mR is defined as [1] ...
This article focuses on the design and analysis of a speed-sensorless vector control of induction motor based upon a Natural Field Orientation (NFO). This method allows high-dynamic vector control of PWM VSI fed induction motor. The main merit of NFO is given by no requirement on any speed or position sensor. The presence of a tacho-generator or optical shaft encoder is commonly undesirable. These transducers significantly increase the costs and reduce the reliability and robustness of the overall system. The NFO method doesn't employ computationally extensive algorithms such as Model Reference Adaptive System or methods based on Kalman filter. Simulation results from a model-based computer-aided design approach using MATLAB/SIMULINK software will be presented.
... The fundamental model of a WRSM in a synchronous frame with the d-axis being aligned with the field winding is given by (1)-(3) [23], where Rd, Rq, Ld and Lq are the d and q-axes resistances and inductances respectively, Lmd is the d-axis mutual inductance, Lf is the field winding inductance, Rf is the field winding resistance, Ns is the stator number of turns, Nfd is the field winding number of turns, v sd r and v sq r are the d-and qaxes stator voltages, i sd r and i sq r are the d-and q-axes stator currents, i fd is the field winding current, v fd is the field winding voltage and ωr is the rotor speed. Primed variables in (1)-(7) are referred to the stator, i.e. i fd ' and v fd ' are the field winding current and voltage referred to the stator, and R f ' and L f ' are the field winding resistance and inductance referred to the stator. ...
... Overall electromagnetic torque of a WRSM is represented by (23) [23], while torque ripple due to the HF signal injection can be expressed as (24), where P is the number of poles. It can be observed that torque ripple results from the interaction among i sq r , i sdHF r and i fdHF ' , i.e. load current, stator d-axis HF current and field HF current respectively. ...
High frequency (HF) signal injection-based has been widely investigated for sensorless position/speed control of permanent magnet synchronous machines (PMSMs). In PMSMs, the HF signal must be injected in the stator windings and an asymmetric (salient) rotor is required. The extension of HF injection-based sensorless methods with wound-rotor synchronous motors (WRSM) is studied in this paper. The fact that rotor terminals are accessible opens interesting possibilities, as avoids the dependency on rotor asymmetries
... The individual phases of a three phase winding will have the same self-inductance, and same mutual-inductance between phases (for proof, refer to [77]). Noting that the mutual inductance between the two stator windings in the BDFM is zero, the stator inductance matrix, M ss ∈ R 6×6 will be of the form of ...
... Neglecting the higher order space harmonics, from [77], ...
The Brushless Doubly-Fed Machine (BDFM) shows promise as a variable speed drive and generator. The BDFM is particularly attractive for use as a generator in wind turbines as the machine's brushless operation reduces maintenance requirements. However, a deeper understanding of the machine is needed before full size generators can be designed. This dissertation contributes towards this goal through machine analysis, modelling and instrumentation.
A system of measuring rotor bar currents in real-time is developed using a Rogowski probe to transduce the signal and Bluetooth wireless technology to transmit data from a moving rotor back to a computer for logging and analysis. The design of the rotor is critical to good performance and direct measurements of rotor currents would help to build confidence in rotor performance as machine sizes increase. As well as verifying theoretical predictions, measurements of rotor currents are employed to acquire parameter values for machine models.
A coupled-circuit model is developed for a general class of BDFMs. A simple analytical method to calculate the parameter values is presented. An equivalent circuit model is derived from the coupled-circuit model by performing suitable transformations. The order of the rotor states is reduced to allow parameter values to be computed for a simple equivalent circuit representation of the machine. Both coupled-circuit and equivalent circuit models are verified by experimental tests on a prototype BDFM.
An experimental method of parameter estimation is developed for the equivalent circuit model, based on the curve-fitting approach. Three widely adopted optimisation algorithms are implemented as the solution methods to the nonlinear problem. The proposed algorithms are compared with respect to their performance, computational cost and simplicity. Rotor current measurements are employed to estimate the parameter values for the full equivalent circuit. A method of obtaining the rotor current in the equivalent circuit from the measured bar currents is presented.
The effects of iron saturation in the BDFM modelling are investigated. A method of calculating the parameter values for the coupled-circuit model, taking tooth saturation into account, is presented. The model is able to calculate the flux density in the machine air gap and stator and rotor teeth. These flux densities are also measured using the flux search coils. The issue of the specific magnetic loading for the BDFM is discussed and its calculation from the fundamental components of the air gap flux density is presented. The equivalent circuit parameter values are derived from the coupled-circuit model and from experimental tests under saturation. It is shown that the predictions of the equivalent circuit model are within acceptable accuracy if its parameter values are obtained at the same operating specific magnetic loading.
... Finally, the last control structure is shown in Fig. 18 (c). The traditional RFOC is responsible for controlling the motor speed, and it is based on (Novotny;Lipo, 1996). The control signals are summed up, normalized and compared by the voltage modulator, in which the phase-shifted pulse width modulation (PS-PWM) with third harmonic injection is considered in this paper Akagi, 2009). ...
... Finally, the last control structure is shown in Fig. 18 (c). The traditional RFOC is responsible for controlling the motor speed, and it is based on (Novotny;Lipo, 1996). The control signals are summed up, normalized and compared by the voltage modulator, in which the phase-shifted pulse width modulation (PS-PWM) with third harmonic injection is considered in this paper Akagi, 2009). ...
The modular multilevel converter (MMC) is an inherently fault-tolerant topology and an interesting option for medium voltage electrical drives, especially when quadratic loads are taken into account. In order to select the optimal blocking voltage for IGBTs, this work presents a design methodology and comparison of MMCs considering the necessary redundancy to achieve the reliability requirement. Designs using commercial IGBTs with blocking voltage in the range of 1.7 to 6.5 kV are compared. The selection is based on complexity, volume, silicon area and efficiency. The methodology application is exemplified through an industrial blower driven by a 13.8 kV - 16 MW three-phase induction motor. Measurements of the operating drive speed and ambient temperature of this process, which is part of a steel industry located in southeastern Brazil, is used as mission profile. The results show that the optimal class of IGBTs depends on the type of redundancy employed. In addition, despite the increase in complexity and the number of components, designs based on IGBTs with lower blocking voltage (1.7 and 3.3 kV) are proved to be more advantageous due to lower losses, converter volume and silicon area.
... In this work, an accurate procedure is proposed: IM performance is derived by performing Magneto-Static (MS) FEA, in which both stator and rotor currents are imposed. In particular, the rotor current is computed connecting the FEA model with the inverse-Γ equivalent circuit, related to the Rotor Field-Oriented (RFO) model [7]. Basically, in the RFO analysis technique, stator and rotor d and q currents have to be imposed in order to verify the condition λ rq = 0, i.e., to reproduce the actual field distribution inside the machine and perform on-load MS simulations. ...
... The flux linkage-current relationships (7) show the first advantage of this IM model: the current i sd is involved in the main flux linkage creation, whilst the current i sq produces leakage flux linkage and implicates the torque production. Furthermore, rearranging (5), it is: ...
Featured Application
The aim of the work is to describe and propose a new approach for the induction machine analysis. The application of the method is immediate for fast and computational efficient procedures for the design optimization and precise performance computation.
Abstract
This paper deals with a complete finite-element analysis procedure for squirrel cage induction motors, including the presence of skewing and the iron losses evaluation. The machine is analyzed performing only magneto-static finite element analyses. Saturation phenomena are carefully considered in any operating condition, avoiding long time-stepping analyses. The synergy between analytical and finite element model leads to a rapid and precise estimation of the rotor induced current, saving computational time. Furthermore, the procedure proposed in this paper allows the motor performance to be directly derived, without the preliminary knowledge of the machine equivalent circuit. In order to complete the analysis, skewing effect is included, using the 2-D multi-slice technique, based on static simulations. Experimental tests are carried out and reported in order to verify analysis results.
... Hence, the design of more reliable SiC power converters requires an accurate lifetime prediction as well as online monitoring strategies for real-time lifetime prediction [15]. Different approaches can be applied to estimate the lifetime of the SiC power devices and power converters [16]. ...
... The model includes a three-phase asynchronous machine whose characteristics are shown in Table 1. The motor is supplied by an ideal three-phase inverter and controlled according to an indirect field oriented control (IFOC) [16]. The mission profile was carried out through the execution of a series of simulations by setting a matrix of reference speeds and reference torques values. ...
This work presents a step-by-step procedure to estimate the lifetime of discrete SiC power MOSFETs equipping three-phase inverters of electric drives. The stress of each power device when it is subjected to thermal jumps from a few degrees up to about 80 °C was analyzed, starting from the computation of the average power losses and the commitment of the electric drive. A customizable mission profile was considered where, by accounting the working conditions of the drive, the corresponding average power losses and junction temperatures of the SiC MOSFETs composing the inverter can be computed. The tool exploits the Coffin–Manson theory, rainflow counting, and Miner’s rule for the lifetime estimation of the semiconductor power devices. Different operating scenarios were investigated, underlying their impact on the lifetime of SiC MOSFETs devices. The lifetime estimation procedure was realized with the main goal of keeping limited computational efforts, while providing an effective evaluation of the thermal effects. The method enables us to set up any generic mission profile from the electric drive model. This gives us the possibility to compare several operating scenario of the drive and predict the worse operating conditions for power devices. Finally, although the lifetime estimation tool was applied to SiC power MOSFET devices for a general-purpose application, it can be extended to any type of power switch technology.
... The space complex vector representation method, introduced in [41] for dynamic analysis of variable frequency ac drives, is used in this paper to simplify the derivations, and the machine variable represented in space complex vector can be given by: (27) Where X can represent any variable of the stator and rotor circuits, X α and X β are α and β components of the variable X in the stationary αβ frame respectively and j is the imaginary unity. The X → (t) can also be expressed by the summation of the positive and negative sequence components, as follow: (28) In (28), subscript + and − represent positive and negative sequence components, X + (t) and X − (t), which are assumed to vary slowly with time, are the magnitudes of the positive and negative sequence components respectively, ω s is the synchronous angular frequency and θ + and θ − are the corresponding phase angles. ...
... Where L r equals (2L lr /3 + L m ). The rotor currents in (38) and (39) are inaccessible, they can be eliminated by substituting (40) and (41) into (38) and (39) and T r equals L r ⁄ (2R r /3) . In (42) and (43), ψ ′ + rd+ and ψ ′ + rq+ are to be eliminated and replaced by ψ + sd+ and ψ + sq+ . ...
... The single phase equivalent circuit of induction motor can be easily used for the determination of motor behavior of torque and current characteristics in terms of speed. For this purpose, the voltage equations of the machine are analyzed in the dq reference frame for the determination of motor performance [5,6]. The torque of the machine in dq reference frame is given by Eq. (1) ...
... FOC improves the dynamic response [11], [12] and its performance can be increased. However, this method is sensitive to small changes in the parameter when temperature changes [13]. Takanashi and Noguchi [14] and Depenbrock [15] ...
... Induction motors (IMs) are robust and reliable and due to their low cost and maintenance they find a wide utilization in industrial applications. A problem consists in their control requiring more complex control circuitry due to variable frequency, complex dynamics, and parameter variations [1][2][3]. The IM itself presents a typical example of a nonlinear and considerably oscillating system with incorporated positive feedback. ...
... The stator stray flux is negligible compared with the stator main flux. Thus, the coupling factor of the main stage ( M 1 L 1 ) is −0.5 [23]. The main CM inductance ...
In this article, a high-frequency (HF) six-port delta- and star-connected three-phase induction motor model is proposed. The model consists of multistage RLC circuits, which include the mutual inductances between the phases. The three-phase HF motor model is derived from common-mode (CM) and differential-mode (DM) equivalent circuits, which are extracted from CM and DM measurements on the motor. A methodology is developed to consider the nonlinear DM inductance effect in the low-frequency (LF) range. The per-phase circuit is symmetric concerning the begin and end points. This symmetry allows us to connect a star configuration into a delta configuration by simply changing the phase connections of the proposed three-phase circuit without recalculating the parameters and vice versa. The three-phase motor model is eventually combined with external circuitry and simulated by a standard circuit solver. The proposed model allows impedance predictions with good accuracy up to 100 MHz. The method is verified with two induction machines, which have 3- and 11-kW rated powers. The proposed HF six-port three-phase motor model can be used for decoupled CM and DM noise predictions as well as for six-port mixed-mode noise prediction.
... The adopted control algorithm is based on the well-known field-oriented control (FOC) [26]. In order to apply it to a multi-phase drive, the model of the motor illustrated in Section III-A is exploited: in fact, given that the torque (9) only depends on the d-q subspace quantities [25], standard FOC can be applied on this subspace, while the remaining current components are controlled to zero by a proportional-integral (PI) regulator. ...
... On the other hand, induction motors became the most widely used in industrial drive applications due to their advantages over other motors. Some of these advantages are: ruggedness, lower rotor inertia, absence of commutator and brushes, besides the lower price and smaller size [2]. ...
Three-phase induction motors have been used in a wide range of industry applications. Using modern technology, the speed of induction motor can be easily controlled by variable frequency drives (VFDs). These drives use high speed power transistors with various switching techniques, mainly PWM schemes. For several decades, conventional control systems were applied to electric drives to control the speed of induction motor. Although conventional controllers showed good results, but they still need tuning to obtain optimum results. The recent proposed control systems use fuzzy logic controller (FLC) to enhance the performance of induction motor drives. In this paper, a fuzzy logic based speed control system is presented. The proposed controller has been designed with MATLAB/SIMULINK software, and it was tested for various operating conditions including load disturbance and sudden change of reference speed. The results showed better performance of the proposed controller compared with the conventional PI controller.
... Therefore, these models can be run very fast and, furthermore, they can be easily implemented in real-time hardware simulator systems (HIL) [54]. Regarding the development of faulty IM models, d-q models are widely used to simulate transient and steady-state phenomena, as well as to reproduce phase unbalances or oscillatory torque during start-up [55]. However, each fault case requires a modification in the model structure [33]. ...
Over the years, induction machines (IMs) have become key components in industry applications as mechanical power sources (working as motors) as well as electrical power sources (working as generators). Unexpected breakdowns in these components can lead to unscheduled down time and consequently to large economic losses. As breakdown of IMs for failure study is not economically feasible, several IM computer models under faulty conditions have been developed to investigate the characteristics of faulty machines and have allowed reducing the number of destructive tests. This paper provides a review of the available techniques for faulty IMs modelling. These models can be categorised as models based on electrical circuits, on magnetic circuits, models based on numerical methods and the recently proposed in the technical literature hybrid models or models based on finite element method (FEM) analytical techniques. A general description of each type of model is given with its main benefits and drawbacks in terms of accuracy, running times and ability to reproduce a given fault.
... Induction motors (IMs) are robust and reliable, and due to their low cost and maintenance, they find a wide utilization in industrial applications. A problem consists of their control requiring more complex control circuitry due to variable frequency, complex dynamics, and parameter variations [1][2][3]. The IM itself presents a typical example of a nonlinear and considerably oscillating system with incorporated positive feedback. ...
The article focuses on a design and experimental verification of continuous nonlinear systems control based on a new control structure based on a linear reference model. An application of Lyapunov’s second method ensures its asymptotic stability conditions. The basic idea in the development of the control structure consists of utilizing additional information from a newly introduced state variable. The structure is applied for angular speed control of an induction motor (IM) drive representing a higher-order nonlinear system. The developed control algorithm helps to achieve the zero steady-state control deviation of the IM drive angular speed. Simulations and experiments performed in various operating states of the IM drive confirm the advantages of the new control structure. Except for set dynamics, the method ensures that the system is stable, invariant to disturbances, and is robust against variations of the parameters. When comparing the obtained control structure of the IM control with the classical vector control, the proposed control structure is simpler. In addition, the proposed control structure is linear, robust against variation in important parameters and invariant against external disturbances. The main advantage over conventional control techniques consists of the fact that the controller design does not require any exact knowledge of the system parameters and, moreover, it does not suffer from system stability problems. The method will find a wide applicability not only in the field of AC controlled drives with IM but also generally in control of industry applications.
... The rotor position is set at 90°behind phase Aaxis, while at θ r =0, the d-axis is in adjustment with the position of the permanent magnet rotor. Since the rotor rotates with the d-q frame of reference at the synchronous angular speed, the PMSG voltage equations under the d-q reference frame and stator flux can be expressed as [87]: ...
Globally abundant wave energy for power generation attracts ever increasing attention. Because of non-linear dynamics and potential uncertainties in ocean energy conversion systems, generation productivity needs to be increased by applying robust control algorithms. This paper focuses on control strategies for a small ocean energy conversion system based on a direct driven permanent magnet synchronous generator (PMSG). It evaluates the performance of two kinds of control strategies, i.e., traditional field-oriented control (FOC) and robust adaptive control. The proposed adaptive control successfully achieves maximum velocity and stable power production, with reduced speed tracking error and system response time. The adaptive control also guarantees global system stability and its superiority over FOC by using a non-linear back-stepping control technique offering a better optimization solution. The robustness of the ocean energy conversion system is further enhanced by investigating the Lyapunov method and the use of a DC-DC boost converter. To overcome system complexity, turbine-generator based power take-off (PTO) is considered. A Matlab/Simulink study verifies the advantages of a non-linear control strategy for an Oscillating Water Column (OWC) based power generation system.
... With the technique of field orientation, the rotor speed is asymptotically decoupled from rotor flux, and the speed is linearly related to torque current. Thus, the IM possesses the same behaviour of a separately excited DC motor [1]. When the motor parameters are considered, particularly the torque, the field-oriented control performance becomes sensitive with the deviation of motor parameters. ...
Today induction motor requires a variable speed control to serve wide range of applications. The objective of this work is to control the position of a field oriented induction motor for a given reference input signal. This work addresses the design of a speed control scheme based on total sliding-mode control (TSMC) theory for a field-orientated induction motor (IM). The total sliding mode control comprises an equivalent control design and a robust control design. In this work the control strategy is derived in the sense of Lyapunov stability theorem such that the stable tracking performance can be ensured under the occurrence of system uncertainties. The salient feature of this control scheme is that the controlled system has a total sliding motion without a reaching phase. The work is been accomplished using Matlab/Simulink. In this work a comparison is been done for a fixed torque & change in torque (Change in motor parameter).
Induction machine (IM) is widely used in most of the industries because of its various advantages. In previous research studies, various studies were completed to analyze the machine flux behavior in different reference frames such as Stationary and Park’s, however, the analysis and comparison for the wide-ranging machine flux behavior, in synchronously rotating stator field-oriented, and rotor-oriented reference frames, is not offered evidently particularly during transients. In addition, the dynamically accurate torque and flux control is an essential requirement for high-performance induction motor drive. A number of techniques, including direct and indirect field-oriented control, direct torque and direct power control techniques, have been developed; however, most of them apply certain approximation criteria to optimize the linear system. It results in inaccurate tuning of respective current, torque and flux controllers, which deteriorates the dynamic performance. In this paper, a novel flux state-based nonlinear control method is presented which results in improved dynamic performance of induction motor drive. The proposed control method is simulated in the MATLAB/Simulink environment and experimentally validated on a 0.75 kW IM. The obtained results show the effectiveness of the proposed flux state-based control method for improved dynamic performance of induction motor drive.
As the dc-link capacitance decreases obviously, the dc-link voltage fluctuates severely in the electrolytic capacitorless permanent magnet synchronous motor (PMSM) drives for compressor applications. The control performance of the compressor deteriorates, and the dc-link may suffer from the fault of overvoltage. In this article, an acceleration extraction-based torque ripple compensation method considering safe operation with dc-link anti-overvoltage is proposed for electrolytic capacitorless PMSM compressor drives. The fluctuation characteristics of the compressor torque and the speed caused by the interaction of the dc-link voltage and the load are analyzed. The load torque is estimated online using the orthogonality theory to suppress the torque ripple. Based on the hybrid proportional–integral–resonant regulator, an anti-overvoltage control strategy is proposed for the safe operation of the regenerating state. Experimental results are performed in the air-conditioner compressor drive system to verify the effectiveness of the proposed method.
The objective of this article isto developa comprehensive mathematical model of a three-phase induction motor to facilitate stator interturn (SIT) fault related study. A detailed analytical model that includes accurate inductance modeling considering rotor slot harmonics (RSH) under healthy as well as SIT faults is described. The proposed model is developed analytically in a step-by-step manner incorporating the features of RSH. A detailed but simplified analysis considering both magnetomotive force harmonics and air-gap flux harmonics has been presented. An asymmetric model is proposed, including SIT faults, in a single phase of the induction motor in the next stage of the modeling. The effect of saturation has also been considered in the model. The proposed model is validated by comparing the simulation results in transient, steady state, and frequency domain with the experimental results. Comparison shows a high degree of correlation with the results of the actual motor. The contributions of this work are justified by comparing the proposed model with the existing models. This article also shows that a frequency signature related to RSH present in the line current is capable of characterizing the SIT faults.
This chapter introduces the concepts to the representation of the induction machine and the three-phase power converter connected to the grid vector control. In this context, it permits control using reactive and active power of the stator of the doubly-fed induction generator by means of the components of the rotor current vector. Regarding the three-phase power converter connected to the grid, it permits control of the reactive and active power using the components of the grid current vector. Additionally, details of the closed loop control using PI controllers, deadbeat rotor current control and direct power control for DFIG, and the grid current control by means of the PI controllers for the converter connected to the grid are presented. The obtained results endorse the presented methods.
Le travail présenté dans cette thèse vise à apporter une contribution à la commande non linéaire des moteurs asynchrones triphasés avec et sans capteur mécanique. De ce fait, plusieurs techniques ont été développées et vérifiées soit par simulation, soit par une validation expérimentale sur un banc d’essai équipé d’une carte dSPACE-RTI-1104. La commande vectorielle indirecte avec orientation du flux rotorique a été adoptée comme structure de base pour la régulation de la vitesse et du courant. L’optimisation du contrôle global sera assurée en utilisant deux variantes des stratégies de commande. La première s’agit du contrôle hybride permettant la combinaison de plusieurs régulateurs en même temps par l’intermédiaire d’un superviseur de régulation. Alors que la deuxième stratégie représente une version avancée du contrôle Backstepping avec action intégrale, la propriété des gains variables a été incorporée dans les différents régulateurs non linéaires afin d’assurer un contrôle optimal du moteur même pour des vitesses très faibles. Dans une deuxième partie aussi importante que la première, l’observation de la vitesse et l’estimation des différentes grandeurs inaccessibles de la machine ont constitué un objectif majeur de ce mémoire. Un observateur linéaire interconnecté a été développé pour assurer une estimation simultanée des différentes résistances des enroulements. Tandis que la commande sans capteur a été réalisée à travers plusieurs approches déterministes et stochastiques comme l’observateur adaptatif flou, les observateurs basés sur la théorie du mode glissant, et l’estimation via le filtre de Kalman étendu. Suite à un examen approfondi des performances générées par le contrôle sans capteur en boucle fermée, une étude comparative permettra d’évaluer les avantages et les inconvénients de chaque technique étudiée.
In this paper, an improved hysteresis-switching table-based current regulation for the field-oriented control (FOC) drive is designed. The control structure of the proposed scheme is similar to the direct torque control (DTC) scheme; therefore, it is named as the hybrid torque and flux control (HTFC) scheme. Conventional HTFC strategy suffers from high current ripple, due to its inefficiency in the selection of optimised switching voltage vectors from the switching table, while limiting d- and q-axes current errors within the hysteresis bands. This is because of the restricted availability of voltage vectors for two-level inverter drive control. To overcome the above problems, the switching table of the HTFC scheme is modified to incorporate intermediate voltage vectors, based on (a) rate of change in q-axis current error, (b) the four-level hysteresis controller state of the q-axis current error, and (c) the two-level hysteresis controller state of the d-axis current error. This proposed Mutated Switching Table – HTFC (MST-HTFC) scheme intends to increase the controllability over stator current component errors, and thus limiting the current ripple. The effectiveness of the MST-HTFC scheme over the HTFC scheme is verified using a 1 kW induction motor drive in simulation through MATLAB and validated experimentally.
Laying power lines to small settlements and farms away from towns and villages is not always cost-effective. Therefore, autonomous solar and wind energy sources are increasingly used in such settlements. In contrast to the dominant today in wind power plants synchronous generators with permanent magnets, an induction generator (IG) with a short-circuited rotor have such important advantages as higher reliability and lower cost. But the energy performance in IG is lower, so their improvement is an actual task. To solve this problem, systems of no-search optimization of power losses in IG are intensively developed. In these systems, the optimal magnetic flux is determined by the analytical expression obtained from the loss model. The disadvantages of the known works on this topic are that they use various simplified models of losses. Accordingly, this reduces the accuracy of optimization algorithms. The aim of the work is to build the vector control system of IG, in which, due to the optimization of the sum of major power losses, a significant increment in the efficiency of the generator is achieved. The article uses a model of power losses, which includes all the main losses in the IG of electromagnetic nature. These include ohmic losses in the stator and rotor resistances, magnetic losses in the iron and additional losses. By analytical study of the model of losses to the extremum, a expression is obtained to calculate the optimal flux linkage of the rotor by the criterion of minimum total losses in the generator. The application of this expression allows to increase the accuracy of loss optimization in comparison with known analogues. Numerical studies of steady-state processes in the mode of operation of the generator with a constant output power P2=const for its values from 10% to 50% have been conducted. It is established that the efficiency increment obtained due to control with loss optimization has an extreme character with a maximum in the vicinity of the nominal speed. The maximum and average efficiency increment obtained in the study reach 26% and 18%, respectively. This shows the prospects of the proposed system of energy-efficient vector control of IG.
This chapter focuses on vector control of AC machines, particularly induction motors, permanent magnet synchronous motors (PMSM), and double fed induction generator. It considers these machines to be the most interesting for modern electric drives and focuses on their control and simulation. The chapter also focuses on the “vector control” schemes of AC machines after a brief description of the scalar control method. At the beginning of the 1970s, the principles of torque and flux control were introduced and called “field‐oriented control” or “vector control” for squirrel cage induction machines and later for synchronous machines. The chapter describes the V/f method and focuses on the vector control approach. Depending on the dynamic requirements and speed control precision, either brushless DC motor or PMSM are used. The chapter provides information on controlling the motor without PWM. It considers PI controllers of the commanded currents.
With the increase proliferation of electric vehicles in the world, the demand for more reliable power electronics drive train is also on the rise. While theoretically the use of multiphase (more than three-phase) motors can increase the reliability of electrical drive train for EV, they are generally not commercially ready and available in the market. Hence, three-phase drive train are still the main stream in current EV technology and the fault-tolerant control of these motor drives remain an interesting and important topic. In this presentation, the existing fault tolerant three-phase motor drive topologies and control methods are reviewed. In particular, the post-fault controls of three-phase motor using 4 legs inverters are discussed and the opportunity for voltage utilization improvement with this configuration is demonstrated.
Renewable energy technique is getting more interest because of extending demand and threat zero carbon foot prints. The increasing demand of wind energy tends to generate a quality output power in terms of grid integration. This paper focuses on various methods and technologies used to analyze the new dynamic stability concerns and control performance of a power system in the context of increased MG penetration. The increased penetration of renewable energy sources (RES) based microgrid (MG) to the power system can affect the system stability because there is difference in dynamic characteristics of this MG from the conventional generators. This paper gives a review of wind energy conversion systems (WECS) and Power System interaction, with an emphasis on the impact of RES based MG penetration on the dynamic stability and control of a multi-machine multi-area system using AI Techniques under varying operating conditions.
The three-pole magnetic bearing is an attractive alternative to the conventional four- and eight-pole magnetic bearings because of its simple structure and ability to be operated with three-phase power electronics. However, accurately controlling the three-pole bearing is significantly more complicated. The conventional control implementations are prone to large force vector errors that can lead to instability in the magnetic suspension system. This article proposes a new control implementation for externally biased three-pole bearings that eliminates force vector error. This control implementation is based on solving a fourth-order polynomial in the form of a depressed quartic to determine coil current commands. An analytic framework and graphic techniques are developed to study the solution space for the bearing's coil currents and explain discontinuities that can arise in certain bearing designs. It is shown that bearings with either no bias or a normalized bias field in excess of
are preferred for suspension stability. The exact force vector regulator is experimentally demonstrated in a bearing prototype and shown to be advantageous over the conventional regulation approach.
High performance electric drive applications necessitate a high fidelity model to predict the terminal characteristics of machines in the design stage to fulfill a system level evaluation together with the converters. This paper interprets winding function theory from the field perspective and incorporates secondary effects like slotting and iron nonlinearity into it to accurately predict the main flux linkage in induction machines. The method is centered on resolving the magnetic scalar potential on the two sides of the air gap and computes the flux linkage via winding function. Its performance is benchmarked against 2D finite element analysis and the state of the art magnetic equivalent circuit (MEC) method. Flux linkage and torque results indicate that the relative error is within 3.1% even in highly saturated region when comparing to finite element analysis, while MEC using the same circuit network may present 20% error.
Der elektrische Strom stellt bei Drehstrommotoren eine zentrale Größe dar: Die eine Stromkomponente bestimmt das Drehmoment, die andere ist für die Flussbildung bzw. Flussschwächung verantwortlich. Während bei I-Umrichtern (stromeinprägenden Umrichtern) der gewünschte Strom dem Motor unmittelbar eingeprägt warden kann, ist bei U-Umrichtern (spannungseinprägenden Umrichtern) eine unterlagerte Stromregelung notwendig, deren Aufgabe es ist, die gewünschten Stromkomponenten entsprechend der Drehmoment- und Flussanforderung sicherzustellen. Diese Stromregelung einschließlich der damit verbundenen Pulsweitenmodulation ist Gegenstand dieses Kapitels.
In this research paper, control of induction motor drive with high-performance characteristics is developed by using vector control, direct-torque control also with the predictive control model. The coordinate transformation has been introduced and established with the mathematical-models of the induction motor (CRH3 high-speed Electric Multiple Units in China Railway) in the two-phase rotating reference frame and the two-phase stationary reference frame. Along-with the discussion of vector control basic principle, the dynamic mathematical-model of the induction motor in the two-phase reference frame is presented. Also, the method of the rotor’s field orientation in the two-phase reference frame is presented. Based on some metro-traction motor parameters of 2.7kV and 1KHz voltages and operating Frequency respectively, MATLAB/Simulink simulation result verifies the principle, control performance, and characteristics of different control strategies, which are comparatively analyzed in detail.
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