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Deadbeat Direct Current Control Using Dynamic Time Programming for Six-Phase PMSM Drives With Open-Phase Faults
Abstract
Due to the influences of the irregular voltage vector distribution, the dynamic optimization problem of six-phase permanent magnet synchronous motor (PMSM) with open-circuit faults is still needed to research. To improve the dynamic ability of six-phase PMSM under open-circuit condition, this article presents a deadbeat direct current control strategy using dynamic time programming, solving the problem of adjusting time optimization under multiobjective complex constraints. Depending on the decoupled transformation matrix, the influences of open-circuit faults on the prediction model and voltage complex plane are analyzed, and the current references under different fault types are given. On this basis, a general control rate for deadbeat fault-tolerant control of six-phase PMSM is constructed, which can achieve high-quality regulation of currents. More importantly, aiming at adjustment time optimization, the standard optimization problem of the transient process is formed, and solved by dynamic programming technology with a core idea of “forward meshing and backward searching”. This time the planning procedure is carried out in the receding horizon pattern, to ensure the high-dynamic ability of the six-phase PMSM with open-circuit fault. The experimental results show that the proposed strategy can significantly improve the dynamic performance of the motor under different fault-tolerant modes, and has good algorithm execution efficiency.
This paper presents an open switch postfault operational technique with enhanced torque-speed region for Three-Level (3L) Active Neutral Point Clamped (ANPC) inverter-driven Symmetrical Six-Phase (SSP) Permanent Magnet Synchronous Machines (PMSMs). Maximum Torque (MT), Minimum Loss (ML), and Single Three-Phase (STP) operations are commonly used for the postfault operations of six-phase drives. The maximum possible torque and speed in these operations are generally limited by voltage, current ratings, and the neutral point configuration of the motor. To enhance the postfault torque and speed operating region, the torque and speed limits in different postfault operational techniques are determined based on the voltage, current constraints, and neutral point configuration of the SSP-PMSM. In this work, a unified postfault operation is proposed that increases the postfault operational limits by combining MT, ML, and STP operations and modifying the neutral point configuration of the SSP-PMSM. In addition, a technique is also presented that modifies the PWM technique to enable full torque operation below 0.5p.u. speed. The proposed postfault operational technique enables full-speed (1p.u.) operation by operating in STP mode and full torque operation (1p.u.) below 0.5p.u. speed. The postfault operational technique is experimentally validated using a GaN-based 3L-ANPC inverter-driven SSP-PMSM.
This paper presents an online open phase and open switch fault diagnosis technique for Three-Level (3L) Active Neutral Point Clamped (ANPC) inverter-fed six-phase Permanent Magnet Synchronous Machine (PMSM) drives with one or two isolated neutral points. One of the main advantages of six-phase PMSM drives is their intrinsic capability to operate at a lower power level in the event of phase or power switch failures. However, for transitioning from pre- to post-fault control, fault detection and fault localization techniques are required. The Open Circuit Faults (OCFs) are commonly detected by observing the post-fault characteristics of the drive. Due to the high number of phases and active switches per phase of 3L-ANPC inverter-fed six-phase PMSM drives, OCF detection is complicated as post-fault characteristics change depending on the location and type of faults. In this paper, OCFs are divided into three categories depending on the location of the fault. The average line current values are used to determine the category and location of the fault. The OCF diagnosis technique is experimentally verified using a GaN-based 3L-ANPC inverter-driven six-phase PMSM prototype.
The main objective of this two parts state of the art paper called ‘Recent Advances in the Design, Modeling and Control of Multiphase Machines’ is to present latest contributions in the multiphase machines’ field. The first part of the work focuses on the recent progress in the design, modelling and control while the drive is in healthy operation. This second part presents relevant contributions in two not analyzed fields. The first is in relation with the use of the additional degrees of freedom of multiphase machines and the exploitation of their fault-tolerant capabilities without adding extra hardware. The second one analyzes multiphase generation, especially in grid-connected wind energy conversion systems and stand-alone applications. Recent progresses are shown and open challenges and future research directions are discussed.
A Takagi-Sugeno-Kang type fuzzy neural network with asymmetric membership function (TSKFNN-AMF) is proposed in this study for the fault-tolerant control of a six-phase permanent-magnet synchronous motor (PMSM) drive system. First, the dynamics of the six-phase PMSM drive system is described in detail. Then, the fault detection and operating decision method is briefly introduced. Moreover, to achieve the required control performance and to maintain the stability of a six-phase PMSM drive system under faulty condition, the TSKFNN-AMF control, which combines the advantages of a Takagi-Sugeno-Kang type fuzzy logic system and an asymmetric membership function, is developed. The network structure, online learning algorithm using a delta adaptation law, and convergence analysis of the TSKFNN-AMF are described in detail. Furthermore, to enhance the control performance of the proposed intelligent fault-tolerant control, a 32-bit floating-point digital signal processor TMS320F28335 is adopted for the implementation of the proposed fault-tolerant control system. Finally, some experimental results are illustrated to show the validity of the proposed TSKFNN-AMF fault-tolerant control for the six-phase PMSM drive system.
In this paper, a novel optimization-based maximum-torque fault-tolerant control scheme is proposed for the open-phase fault of dual three-phase permanent-magnet synchronous motor (DTP-PMSM) drive. First, the relationship between torque output capability and single-phase copper losses under open-phase fault is derived with the consideration of overheating problems. Since the derived expression has multiple optimization goals, a new objective function is designed to simplify the current optimization. Second, Particle Swarm Optimization (PSO) is utilized to obtain the maximum-torque current references based on the designed objective function. Different from the conventional maximum-torque fault-tolerant schemes which limit the current patterns, the proposed fault-tolerant control scheme employs PSO to search for the global optimal result without adding any unnecessary restrictions such as sinusoidal current patterns. In this way, the proposed fault-tolerant control scheme can achieve the theoretical highest torque output capability of 73.3% with lower total copper loss. Both the theoretical and experimental results are presented to prove the effectiveness and superiority of the proposed optimization-based maximum-torque fault-tolerant control scheme.
The concept of virtual vector has been a standard practice for the multiphase machine drives. However, simply adopting the fixed or adjustable duty-ratio virtual vectors fails to mitigate the current tracking error in the fundamental plane satisfactorily. To that end, this paper proposes a new MPC method for a six-phase permanent magnet synchronous motor (PMSM) using multi-step synthesis based virtual vectors to regulate two planes simultaneously. The virtual vectors are formed through a two-step synthesis process. First, two groups of real vectors are used to synthesize 12 elementary virtual vectors to nullify the harmonic currents in the secondary plane. Subsequently, the 12 elementary virtual vectors are employed to further form other 60 composite virtual vectors to enhance the current tracking in the fundamental plane. For the sake of easy practical implementation, the pulse width modulation (PWM) switching sequence of all virtual vectors are analyzed to ensure that they present standard PWM switching sequence. The proposed multi-step synthesized composite virtual vectors can suppress the harmonic currents in the secondary plane and reduce the current tracking error in the primary plane simultaneously. Experimentations are conducted to verify the effectiveness of the proposed method.
This paper proposes a decoupled fault-tolerant model predictive current control for dual three-phase permanent magnet synchronous motor with harmonic compensation. The harmonics caused by nonsinusoidal back electromotive force can be well controlled under the open-circuit fault scenario by designing a harmonic closed-loop scheme. First, a decoupled predictive model and fault-tolerant voltage vectors are deduced based on a reduced-dimension matrix, which can eliminate the coupling issues between harmonic and fundamental subspace. Afterward, a uniform harmonic-free virtual vector is constructed by rearranging the irregular voltage vectors. More importantly, a virtual null vector is designed in the scheme, where the virtual null vector is effective in the harmonic subspace and has no components in the fundamental subspace. So, the harmonics can be further controlled without affecting torque and flux generation. Extensive experimental results verify the effectiveness of the proposed method.
In multi-stages aircraft starter/generator system, the main machine (MM) and main exciter (ME) are fed by a generalized dual-inverter configuration, allowing for common-mode voltage (CMV) elimination. However, the distinction in load impedances and voltage requirements between the two sub-inverters has evidently contributed to the sub-load asymmetry, which may impair the suppression effect of system common mode (CM) noises. This paper presents a CMV minimization method for the generalized dual-inverter application. The available freedom, such as the selection and action sequence of voltage vectors, is appropriately arranged in the suggested implementation to eliminate the total CMV, restrict the sub-CMVs and fulfill the voltage requirements of sub-inverters all at the same time. In the meanwhile, a theoretical study is performed to evaluate the CM noise features of zero CMV technique in the generalized dual inverter-fed system. In the situation of sub-load asymmetry, the premise and main influence element for CM noise reduction are assessed. Finally, these findings are verified by simulation and experiments.
For the dual three-phase interior permanent magnet synchronous machines (DT-IPMSMs), open-phase fault can cause current unbalance and degrade the drive performance. This article proposes a fault tolerant maximum torque per ampere (FT-MTPA) control for DT-IPMSMs, which can maximize the ratio of the average torque to the stator current and minimize the fault-induced torque ripple. In the proposed approach, optimal FT-MTPA solution is derived and theoretically proven, and current rms is considered as one design constraint to ensure the equivalent loss to the healthy condition. The proposed FT-MTPA control ensures the smooth switching between fault tolerant control and healthy control without inducing noticeable torque ripple. Compared with existing methods, the proposed approach is computation-efficient and fast in achieving the FT-MTPA control, which is critical to practical applications with fast changing loads. Moreover, this article derives the optimal solution from the faulty MTPA model with fault induced terms considered to ensure high torque. Experiments and comparisons with existing methods are conducted to evaluate the proposed approach on a laboratory DT-IPMSM.
This article proposes an improved multiple synchronous reference frame (MSRF) current harmonic regulation strategy for dual three phase permanent magnet synchronous machine drive system. A new vector space decomposition transformation combined with auxiliary currents is designed to decouple the current fundamental with current harmonics, and the auxiliary currents can be established by the π/9 phase shifting of the physical currents in
ABC
set and the π/18 phase shifting of the physical currents in
XYZ
set. By employing the proposed current decomposition, it is easy to detect them using low pass filters in MSRFs. A generic complex vector proportional integral regulator is then employed to control the detected current harmonics to track the current harmonic references. Compared with the existing MSRF-based methods, the proposed method provides a new current harmonic detection with reduced delay effect, which contributes to enhancing the dynamic performance of current harmonic regulation, and also stabilizing the control system. Comprehensive experimental results are given to validate the effectiveness of the proposed control strategy.
Multiphase machines, associated to state-of-the-art control strategies like finite control set model predictive control (FCS-MPC) are suitable for applications where reliability and disturbance-free operation are key factors. Although FCS-MPC provides good transient performance and straightforward design, the performance of the drive system is affected by model inaccuracies due to parameter mismatch and unmodeled dynamics, such as deadtime effects in the power converters and back-EMF harmonics. In this context, this paper proposes a novel and robust disturbance-observer-based predictive current control strategy for six-phase permanent magnet synchronous machine (PMSM) drives that minimizes the steady-state errors due to parameter mismatch errors, while simultaneously reducing the amplitude of the fifth and seventh order current harmonics due to unmodeled dynamics, which are non-negligible in six-phase machines. Simulation and experimental results demonstrate the very good performance of the proposed strategy even when considering significant errors in the system parameters and different values of the deadtime in the power converters.
A fault-tolerant hybrid current control is proposed for dual three-phase permanent magnet synchronous machines (PMSMs) with one phase open in this article. The maximum torque control, minimum copper loss control, and single three-phase mode control are unified in the proposed method, which is a combination of single three-phase mode control and maximum torque control with different percentages. When the percentage of single three-phase mode control (
k
) varies from 0% to 100%, the hybrid current control transitions from maximum torque control (
%) to minimum copper loss control (
%) and then to single three-phase mode (
%). Therefore, the hybrid current control can be switched among the aforementioned three control methods easily and smoothly. Meanwhile, it can be a mixed mode with a tradeoff between the maximum torque control and the minimum copper loss control, such as the minimum copper loss control for a given torque within the full torque range, which can be achieved by changing
k
. The smoothness of transition among the maximum torque control, minimum copper loss control, and single three-phase mode control is verified by experimental results on a prototype machine.
In this paper, a deadbeat predictive current control based fault-tolerant control scheme is proposed for common electrical faults in T-type three-level inverter fed dual three-phase PMSM drives, which aims at providing a solution for the application of high power rating, low switching frequency, low complexity and high reliability. Firstly, deadbeat control is combined with current prediction to obtain precise voltage reference for the current control. Each three-phase three-level inverter generates a single optimal inverter voltage vector based on a new division method of space vector diagram. In this way, both low switch frequency and high control precision can be guaranteed in a high-power motor system. Secondly, fault-tolerant control schemes are designed for five types of common electric faults in T-type three-level inverter fed dual three-phase PMSM without changing the mathematical model and control framework. Thus, the complexity of the proposed fault-tolerant control schemes can be avoided and smooth transition can be guaranteed. The validity of the proposed schemes is verified by experimental results.
The inherent fault-tolerant capability of multiphase machines is highly appreciated, but it requires fault detection and localization together with a reconfiguration of the control scheme. When the multiphase machine is regulated using finite-control set model predictive control (MPC) strategies, the reconfiguration involves the use of different transformation matrices, cost functions and current references for each of the multiple open-phase fault (OPF) scenarios. Aiming to simplify this procedure and add further robustness, this paper explores the possibility to achieve a natural fault-tolerant capability by maintaining the pre-fault control strategy after the fault occurrence. For this purpose, this work firstly analyzes the two main reasons why MPC-regulated multiphase drives misbehave in the event of an OPF: the voltage vector shifting and the search for incompatible goals. In a next step, a version of the MPC that includes virtual voltage vectors (VVs) is tested for the first time in post-fault situation and it is compared to conventional MPC technique. Extensive experimental results reveal that, while MPC misbehaves in the event of an OPF, the VV-MPC provides a satisfactory ripple-free post-fault performance. This finding has two significant implications for industrial applications: the post-fault operation is highly simplified and, at the same time, the fault-tolerant multiphase drive becomes immune to fault detection errors and delays.
This paper investigates open-phase fault modeling and fault tolerant control (FTC) of dual three-phase permanent magnet synchronous machines. A comprehensive fault model that considers both the permanent magnet torque and reluctance torque under the open-phase fault is proposed at first. This model shows that under open-phase fault the average torque of dual three-phase PMSM will decrease, while torque ripple will increase significantly. Then, a novel optimized FTC approach is developed based on the proposed fault model, in which genetic algorithm (GA) is applied to optimize the stator currents to maximize the average torque and minimize the torque ripple under open-phase fault condition. The proposed fault model and GA-based FTC are applicable to both surface-mounted and interior dual three-phase PMSMs. However, existing approaches are only applicable to the surfaced-mounted dual three-phase PMSMs because the reluctance torque has been neglected. Moreover, the proposed approach is simple in implementation as it employs the original control structure, and it is capable of smooth switching between the healthy operation and FTC without inducing noticeable torque pulses. The proposed GA-based FTC is demonstrated with design examples, compared with existing approach and validated with experimental tests on a laboratory interior dual three-phase PMSM.
Multiphase machines are famous for the fault-tolerant capability. Conventional fault-tolerant model predictive current control (FT-CMPC) of multiphase machines suffers from the high computational burden, low switching frequency and relatively high current harmonics. This paper proposes a fault-tolerant PWM predictive control (FT-PWMPC) to enhance the performance of fault-tolerant predictive control strategy without the use of complex enumeration method. The reference phase voltages are generated by a post-fault mathematical model in stationary reference frame and transformed to duty cycles with a proper set common-mode voltage. Then a comparative study of fault-tolerant predictive control strategies is presented, including FT-CMPC, FT-two-vector-based-predictive control (FT-TVPC) and the proposed FT-PWMPC. The control strategies are implemented with the same sampling frequency or switching frequency on a six-phase permanent magnet synchronous machine (PMSM) test bench. Experimental results of dynamic response, steady-state currents, vibration and parameter sensitivity are given to identify the advantages and limitations of each control strategy. IEEE
The most serious and recent competitor to the standard field oriented control (FOC) for induction motors (IM) is the finite control set model predictive control (FCS-MPC). Nevertheless, the extension to multiphase drives faces the impossibility to simultaneously regulate the flux/torque and the secondary current components (typically termed x-y in literature). The application of a single switching state during the whole sampling period inevitably implies the appearance of x-y voltage/currents that increase the system losses and deteriorate the power quality. These circulating currents become intolerably high as the per unit x-y impedance and the switching frequency diminish. Aiming to overcome this limitation, this work suggests the integration of v irtual voltage vectors (VVs) into the FCS-MPC structure. The VVs ensure null x-y voltages on average during the sampling period and the MPC approach selects the most suitable VV to fulfill the flux/torque requirements. The experimental results for a six-phase case study compare the standard FCS-MPC with the suggested method, confirming that the VV-based MPC maintains the flux/torque regulation and successfully improves the power quality and efficiency.
Multiphase machines are well recognized as an attractive alternative to conventional three-phase machines in a number of applications where high overall system reliability and reduction in total power per phase are required. The pace of developments in the field has accelerated in the last few years, and substantial knowledge has been recently generated. The main objective of the two-part survey named 'Recent Advances in the Design, Modeling, and Control of Multiphase Machines' is to present relevant contributions to encourage and guide new advances and developments in the field. More specifically, part 1 of the work analyzes the recent progress in the design, modeling, and control, including healthy operation, of multiphase motor drives, and discusses open challenges and future research directions in the area.
In this paper, a fault-tolerant control is proposed for dual three-phase permanent-magnet synchronous machine (PMSM) drives under open-phase faults. The object of the proposed fault-tolerant control is to maximize the torque capacity while the overcurrent protection is taken into account. Hence, the proposed fault-tolerant control is named as torque mode in this paper. Another existed fault-tolerant control for dual three-phase PMSM drives under open-phase faults is loss mode, in which the system copper loss is minimized. Torque mode is compared with loss mode, and two important conclusions are given: 1) loss mode can reduce more copper loss; and 2) torque mode can output more torque. The performances of torque mode and loss mode are verified by experimental results.
Recent advances in the design, modeling, and control of multiphase machines—Part II
- M J Duran
- F Barrero