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Sensorless Control of Synchronous Machine With an Inverter Integrated Rotor
Abstract
This paper proposes a new sensorless method for a Synchronous Machine with an Inverter Integrated Rotor (SMIIR). The SMIIR is a newly developed machine based on the wound rotor synchronous machine (WRSM) but has no brushes and slip-rings. And conventional high-frequency signal injection sensorless methods are based on physical magnetic saliency. Therefore, conventional methods cannot be applied to the SMIIR which has no sufficient magnetic saliency. The proposed sensorless method suggests virtual resistance saliency created by the rotor-side inverter, whose axes can be placed arbitrarily. Based on this virtual saliency the rotor position information is included and excluded in the relationship between the high-frequency stator voltage and stator current. Because the SMIIR already injects high-frequency voltage for the power transfer, there is no need to inject additional voltage for the proposed high-frequency sensorless method. And initial +d axis detection algorithm using the rotor-side inverter without using magnetic saturation is also proposed. The feasibility of the proposed sensorless method was verified by experimental results with the prototype SMIIR.
... This problem is even more severe to the MEA, due to MEA needs more starting torque for the engine. Many studies have focused on torque or speed control of different types of motors to achieve faster speed control or higher torque density, and there have been many different sensorless control strategies [13]- [17]，such as vector control [18]- [21], direct torque and flux control [22]- [24], etc. Along with the excitation requirements of three-stage S/G system goes more and more stringent when they are applied in high-speed and high-load situations, the related researches is gradually in-depth [25]- [29]. ...
More electric aircraft (MEA) and all electric aircraft (AEA) are the development trends of new generation aircraft. With the increasing dependency on electrical power in MEA, dual-function electrical machinery technology is the inevitable trend of the aircraft engine-driven generator. This paper proposes an active control excitation method to produce enough electromagnetic torque to realize the smooth electric starting of aircraft engine by the three-stage brushless synchronous Starter/Generator(S/G). The main DC/AC invertion module in the DC/AC invertor supplies a three-phase current to the main S/G stator windings. The module adopts an active control method that the current is adjusted by a reference three-phase current which varies as a function of rotor shaft position and rotation speed. Meanwhile, the exciter power supply module in the DC/AC invertor supplies a single-phase AC current to the auxiliary exciter stator winding. This part also adopts an active control method that a current hysteresis tracking control strategy is taken and the scheduled current is adjusted as a function of the rotor rotation speed. Simulation results verify the effectiveness of the electric starting excitation strategy. The two magnetic fields generated by the stator and rotor windings of the main S/G interacts each other, which produces enough electromagnetic torque to drive the starter from the stationary state.
This paper analyzes the effects of the high-frequency resistances in saliency tracking-based sensorless control methods of permanent-magnet synchronous machines (PMSMs). A high-frequency model of the PMSM, including stator high-frequency resistance, is presented. From this model, potential sources of error in the estimated position due to the high-frequency resistances are analyzed, and their compensation by means of an adaptive decoupling mechanism is proposed. This paper also addresses the influence and compensation of temperature effects in carrier-signal-injection-based sensorless techniques.
Controlled induction motor drives without mechanical speed sensors at the motor shaft have the attractions of low cost and high reliability. To replace the sensor, information on the rotor speed is extracted from measured stator currents and from voltages at motor terminals. Vector-controlled drives require estimating the magnitude and spatial orientation of the fundamental magnetic flux waves in the stator or in the rotor. Open-loop estimators or closed-loop observers are used for this purpose. They differ with respect to accuracy, robustness, and sensitivity against model parameter variations. Dynamic performance and steady-state speed accuracy around zero speed range are achieved by signal injection, exploiting the anisotropic properties of the machine. The overview in this paper uses signal flow graphs of complex space vector quantities to provide an insightful description of the systems used in sensorless control of induction motors.
This paper presents a position and speed estimation algorithm based on magnetic saliency of permanent-magnet synchronous motors. The proposed method uses inherent high-frequency content of motor pulsewidth-modulation (PWM) excitation to measure position-dependent inductance parameters, which are then processed using a simple nonlinear observer to produce the position and speed estimates. To ensure persistent excitation at all operating voltages (speeds), a novel PWM algorithm with full voltage output is developed and presented. The efficiency of the modified excitation was evaluated and compared to the efficiency of the standard position-sensorless motor drive excitation. Experimental results are presented as well, showing good algorithm performance in a wide speed range, including zero, and for various load torques.
In this paper, a synchronous motor with an inverter integrated rotor (SMIIR) is introduced, and its control scheme is proposed. This presents a new breed of synchronous motor in that it integrates an inverter inside the rotor. The basic operational principle and control strategies are discussed. Given these new strategies, the SMIIR can be considered as a synchronous motor which changes its field according to the harmonic voltage of the stator inverter. The feasibility of the proposed structure of the drive system and its operation principle are evaluated through experimental results.
The rotor position of an interior permanent-magnet synchronous machine (IPMSM) can be estimated without a position sensor by signal injection sensorless control at standstill and/or in very low speed rotating condition. In the signal injection sensorless control, however, the fundamental control performance is limited by the frequency of the injected signal, and no negligible acoustic noise is generated. If the frequency of the injected voltage signal would increase to pulsewidth modulation (PWM) switching frequency and if the switching frequency is near or above audible range, the dynamics of the sensorless control can be improved, and the acoustic noise can be remarkably reduced or totally eliminated. This paper describes how to extract the rotor position information of IPMSM using the voltage signal injection whose frequency is the same as the PWM switching frequency. Compared to the conventional heterodyning process, the proposed method is simple to implement and appropriate for PWM switching frequency signal injection. The high-frequency voltage signal can be injected in the stationary reference frame or in the estimated rotor reference frame. In this paper, the 5- and 16-kHz signal injections are proposed, implemented, and compared. The experimental results confirm the effectiveness of the proposed method.
Numerous methods have been published for sensorless detection of the rotor position in PM synchronous motors (PMSM) by evaluating the magnetic anisotropy. In this paper, the one based on the injection of an alternating voltage carrier is considered. It is able to detect the anisotropy, and by its means the rotorpsilas position, without any additional hardware or modifications on the samplings times. It will be shown that the observerpsilas dynamics is bounded by the carrier frequency. The carrier is usually sinusoidal and with a frequency of about 1/4 of the switching frequency or lower. As a measure to improve the dynamics of the position observation, a square wave carrier with the highest possible frequency, namely the switching frequency, will be used. In addition, the carrier response will be decoupled from the controlled q-current in order to avoid the usual bandpass filter. This filter would introduce a significant delay in the observer loop. The frequency increase, together with the removal of the filter allows a faster time response in the position estimation. Experimental results showing the improvements in the estimationpsilas dynamics are presented.
This paper proposes a new position sensorless control method based on the high frequency signal injection. The frequency of the signal is increased up to 2/3 of the switching frequency, and the dynamics of the sensorless control can be improved. Furthermore, the audible noise is reduced conspicuously due to the increased frequency of injected signal. In this method, the rotor position is directly calculated from three successively sampled currents and voltages without any filter. The injected signal comes from three voltage vectors rotating at the stationary reference frame. The 15Hz speed control bandwidth and 300Hz current regulation bandwidth has been demonstrated with the experimental test results.
This paper describes a new control algorithm which can enhance the dynamics of a sensorless control system and gives a precise sensorless control performance. Instead of the conventional sinusoidal-type voltage injection, a square-wave-type voltage injection incorporated with the associated signal processing method is proposed in this paper. As a result, the error signal can be calculated without low-pass filters and time delays, and the position estimation performance can be enhanced. Using the proposed method, the performance of the sensorless control can be enhanced; the bandwidth of the current controller was enhanced up to 250 Hz, and that of the speed controller was up to 50 Hz.
This paper describes position-sensorless control of an interior permanent magnet synchronous (IPM) motor, which is characterized by real-time position estimation based on magnetic saliency. The real-time estimation algorithm detects motor current harmonics and determines the inductance matrix, including rotor position information. An experimental system consisting of an IPM motor and a voltage-source pulsewidth modulation inverter has been implemented and tested to confirm the effectiveness and versatility of the approach. Some experimental results show that the experimental system has the function of electrically locking the loaded motor, along with a position response of 20 rad/s and a settling time of 300 ms
This paper presents a method using carrier frequency injection to estimate the initial rotor position and magnet polarity for an interior permanent magnet synchronous machine. A non-saturating inductance model of the machine provides no information about the polarity of the rotor magnet because the position observer based on this model is locally stable at both poles. To distinguish the polarity of the rotor magnet, the magnetic saturation effect can be used. A 2<sup>nd</sup> order Taylor series can be used to describe the nonlinear magnetic saturation relationship between the current and the flux linkage in the d-axis rotor reference frame. The 2<sup>nd</sup> order term produces the 2<sup>nd</sup> harmonic component of the carrier frequency, and the sign of its coefficient identifies the polarity of the rotor magnet being tracked. Both simulation and experimental results show good response of the position observer at rotor electrical positions of ±0.5π rad using either a rotating vector in the stationary reference frame or a pulsating vector in the estimated rotor reference frame.
This paper presents a new position sensorless control system of an
interior permanent magnet synchronous motor (IPMSM) for electric
vehicles. The proposed control system is based on an injected voltage
vector that is synchronized with a PWM carrier of an inverter. The pole
position is estimated from the relation between the injected voltage
vector and the saliency of the rotor. The first current difference
vector is detected when the injected voltage vector in the estimated
pole position direction is added to the motor control voltage vector.
Next, the second current difference vector is detected when the injected
voltage vector in the opposite direction of the estimated pole position
is added to the same motor control voltage vector. Then, the pole
position of the rotor with anti-saliency can be estimated from the first
and second current difference vectors. This control needs neither motor
parameters nor band pass filters. The anti-salient pole type IPMSM can
be operated over a wide speed range including zero speed, with a quick
response. Good driving of electric vehicles is realized using the
proposed system
This paper describes a torque, speed or position control method at the stand still and low speed in the interior permanent magnet (IPM) motor drive system without any rotational transducer. While IPM motors originally have magnetic saliency, it varies according to the load conditions and the control performance can be easily degraded. In this paper the saliency or impedance difference is used as the conventional methods and, nevertheless, in order to amplify the difference containing the information of the rotor angle and to maintain a reasonable performance under any load condition, a high frequency injection scheme is proposed. A speed and position estimation scheme based on the characteristics of the high frequency impedance is proposed. The scheme extracts the high frequency impedance components related to the rotor position. An initial angle estimation scheme for the starting from an arbitrary rotor position is also proposed. It can distinguish the north magnetic pole position from the south one in several tens of milliseconds. The proposed scheme enables position control of a transducerless or position-sensorless IPM motor. The experimental results clarify the satisfactory operation of the proposed position control algorithm under any load condition.
The increasing use of AC machines compared to DC motors in
electrical drive applications has several reasons. A very important
advantage of AC machines is their simple construction. However, AC
drives often need mechanical sensors (tachometers, position encoders)
for field orientation. In many applications these sensors reduce
robustness and increase costs of a drive considerably. The main
objective of this paper is to present the “INFORM” method
based on real-time inductance measurements for sensorless control of AC
drives
A brushless DC motor without a position sensor is described. Variable speed is achieved by adjusting the average motor voltage, just like chopper control of DC motors. The position-sensorless drive proposed is based on detection of the conducting interval of free wheeling diodes connected in antiparallel with power transistors. This approach makes it possible to detect the rotor position over a wide speed range, especially at a lower speed. Experimental results obtained from a prototype brushless DC motor with a rating of 300 W are shown to confirm the validity of the sensorless drive from 45 to 2300 r/min. The starting procedure of the motor is also discussed because it is impossible to detect the rotor position at a standstill
The operation of a brushless permanent-magnet machine requires rotor-position information, which is used to control the frequency and phase angle of the machine's winding currents. Sensorless techniques for estimating rotor position from measurements of voltage and current have been the subject of intensive research. This paper reviews the state of the art in these sensorless techniques, which are broadly classified into three types: motional electromotive force, inductance, and flux linkage.
This paper proposes a hybrid speed estimator that gives the synergetic effect between the model- and the saliency-based field orientations for induction motor drives. The model-based field orientation consists of a flux observer with an adaptive speed estimator that has unstable regions at zero frequency and zero speed. Saliency-based flux orientation utilizes magnetic saliencies caused by saturation and high-frequency injection that causes the torque ripples due to the chattering. The chattering is caused by the higher cutoff frequency of the flux-angle estimation to keep its high dynamics. The proposed method compensates both faults and realizes complete speed estimation from zero to high-speed condition including zero stator frequency.
In this paper a novel interior permanent-magnet (IPM) motor's rotor position extraction method from the carrier-frequency component signal, derived from pulsewidth-modulated (PWM) inverter switching, using two reference frames is presented. This method has been utilized for IPM motor vector control without a mechanical rotor position detector, extracting rotor position angle from the switching carrier-frequency (10 kHz) component current. It is effective for IPM motors, which have magnetic saliency, sinusoidal distributed stator winding, and are supplied by a PWM voltage-source inverter. The performance of two IPM motors' vector control without mechanical rotor position detector utilizing this method has been investigated. Experimental results demonstrating good dynamic and steady-state performance achieved are presented and discussed.
This work presents a method using carrier-frequency injection to estimate the initial rotor position and magnetic polarity for an interior permanent-magnet synchronous machine. A nonsaturating inductance model of the machine provides no information about the polarity of the rotor magnet because the position observer based on this model is locally stable at both poles. To distinguish the polarity of the rotor magnet, the magnetic saturation effect can be used. The Taylor series can be used to describe the nonlinear magnetic saturation relationship between the current and the flux linkage in the d-axis rotor reference frame. The second-order term produces the second harmonic component of the carrier frequency, and the sign of its coefficient identifies the polarity of the rotor magnet being tracked. Both simulation and experimental results show good response of the position observer at several rotor electrical positions using either a rotating vector in the stationary reference frame or a oscillating vector in the estimated rotor reference frame.
This paper presents a new sensorless control scheme of a surface-mounted permanent-magnet (SMPM) motor using high-frequency voltage signal injection method based on the high-frequency impedance difference. In the SMPM motor, due to the flux of the permanent magnet, the stator core around the q-axis winding is saturated. This makes the magnetic saliency in the motor. This magnetic saliency has the information about the rotor position. The high-frequency voltage signal is injected into the motor in order to detect the magnetic saliency and estimate the rotor position. In this paper, the relationship between the high-frequency voltages and high-frequency currents is developed using the voltage equations at the high frequency, and the high-frequency impedance characteristics are analyzed experimentally under various conditions. The proposed sensorless control scheme makes it possible to drive the SMPM motor in the low-speed region including zero speed, even under heavy load conditions. The experimental results verify the performance of the proposed sensorless algorithm.
This paper describes a torque, speed, or position control method at standstill and low speed in the interior permanent-magnet motor (IPMM) drive system without any rotational transducer. While IPMMs have originally magnetic saliency, it varies according to the load conditions and the control performance can be easily degraded. In this paper, the saliency or impedance difference is used as the conventional methods and, nevertheless, in order to amplify the difference containing the information of the rotor angle and to maintain a reasonable performance under any load condition a high-frequency injection scheme is proposed. A speed and position estimation scheme based on the characteristics of the high-frequency impedance is proposed. The scheme extracts the high-frequency impedance components related to the rotor position. An initial angle estimation scheme for starting from an arbitrary rotor position is also proposed. It can distinguish the north magnetic pole position from the south one in several decade milliseconds. The proposed scheme enables position control of a transducerless or position-sensorless IPMM. The experimental results clarify the satisfactory operation of the proposed position control algorithm under any load condition.
This paper describes a new scheme to find the rotor flux angle
from stator voltages and currents by injecting high-frequency signal.
The signal is not a rotating one, but a fluctuating one at a synchronous
rotating reference frame with the fundamental stator frequency. When the
estimated rotor flux angle coincides with the actual angle, the proposed
method makes virtually no ripple torque, no vibration and less audible
noise caused by the injected signal. The difference of impedances
between the flux axis and the quadrature axis at high-frequency signal
injection on the rotor flux angle is explained by the equivalent circuit
equation of the induction machine. The difference is verified by
experiments on the test motors at various testing conditions. The
sensorless field-orientation algorithm is proposed, and the experimental
results clarify the satisfactory operation of the algorithm with 150%
load torque at zero stator frequency
This paper addresses self-sensing (“sensorless”)
control of salient-pole permanent magnet synchronous motors (PMSMs). The
major contribution of this work is the introduction of a
simple-to-implement estimation technique that operates over a wide speed
range, including zero speed. The technique achieves simplicity by
decoupling the inherent cross-coupling in PMSMs. The technique utilizes
the dependence of inductance on rotor position in interior permanent
magnet machines to produce position and velocity estimates both for
field orientation and for all motion control of the drives. The
technique functions in a manner similar to a resolver and
resolver-to-digital converter (RTDC) sensing system, whereby in the
proposed technique the motor acts as the electromagnetic resolver and
the power converter applies carrier-frequency voltages to the stator
which produce high-frequency currents that vary with position. The
sensed currents are then processed with a heterodyning technique that
produces a signal that is approximately proportional to the difference
between the actual rotor position and an estimated rotor position. This
position error signal and a torque estimate are then used as inputs to a
Luenberger style observer to produce parameter insensitive, zero lag,
position and velocity estimates
Most industry experts agree that the next generation of commercial
drives will include some sort of sensorless torque control. Achieving a
modest level of control in the very-low-speed range greatly increases
the competitive value of the drive and expands its range of
applications. After reviewing many of the previously presented
sensorless control methods, this paper shows that the simple method of
stator-flux orientation can provide zero-speed torque control equally as
well as more complex approaches, which rely on elaborate mathematical
models to improve the operating range. This paper experimentally
demonstrates that, by using only a slight amount of low-pass filtering
in the integration of the stator voltage, a reasonable flux estimate can
be obtained for stator-flux-field-oriented torque control. With this
simple method, adequate torque control has been demonstrated over a wide
range of speed and load conditions, and even at zero rotor speed with
moderate or heavy load torque
This paper presents a viable transducerless rotor position and
velocity estimation scheme for PWM inverter driven induction,
synchronous, and reluctance machines with the capability of providing
robust and accurate dynamic estimation independent of operating point,
including zero and very high speeds, light and heavy loading. The
injection of a balanced three-phase high frequency signal (500 to 2 kHz)
generated by the inverter, followed by appropriate signal demodulation
and processing combined with a closed-loop observer, enable the tracking
of rotor magnetic saliencies from the machine terminals. Although rotor
magnetic saliency is inherent within reluctance machines, and most
synchronous machines, saliency in the induction machine is introduced
via a modulation of the rotor slot leakage with minimal detrimental
effects on the machine performance. Experimental verification for the
induction machine is included
A theoretical and experimental analysis of a closed-loop adaptive
velocity control system for a 200 W permanent-magnet synchronous motor
(PMSM) is presented. The control system utilizes a mechanically
sensorless full-state observer for the generation of all controller
feedback information. Both the control system and its experimental
performance using an implementation based on the Motorola 68020
microprocessor are presented in detail. It is shown that the real-time
observer-based adaptive velocity controller is capable of successful
operation
An approach to the position sensor elimination of an interior
permanent magnet (IPM) synchronous motor drive is proposed. The phase
inductance of an IPM synchronous motor varies appreciably as a function
of the rotor position. This feature is utilized to get an estimate of
the rotor position. Analytical equations are developed for the
calculation of the phase inductance of an IPM motor driven by a
current-controlled PWM power converter with a hysteresis controller. The
calculated phase inductance is used to estimate the position of the
rotor. To obtain an unambiguous relation between the phase inductance
and the rotor position, the phase inductance of phases a , b
, and c is calculated during different segments of each
electrical cycle. A direct approach to inductance calculation is
proposed. Simulation results show the effectiveness of the controller.
The position error is very small for speed control applications. A
current regulator using constant-frequency switching is analyzed in
order to avoid the random switching of the hysteresis current controller