Control Of Permanent Magnet Synchronous Machines Research Articles

A Quasi Edge Aligned Pulse-Width Modulation to Enhance Low-Speed Sensorless Control of PMSMs With a Single DC-Bus Current Sensor

The low-speed sensorless control of permanent magnet synchronous machines (PMSMs) with a single DC-bus current sensor has not been solved thoroughly from the prior literatures. This article proposes a novel quasi edge aligned pulse-width modulation (QEAPWM) to realize this purpose. Compared with the conventional phase-shifting PWM, the QEAPWM has several advantages of the accurate reconstructed phase-current and the fixed current sampling time interval, which are beneficial to obtain the current ripple evoked by the high-frequency (HF) injected voltage to estimate rotor position. The effectiveness of the proposed method is verified on a 500-W PMSM drive and compared with three state-of-the-art methods. The experimental results verify that the QEAPWM-based sensorless control achieves satisfactory performance both in the transient and steady-state processes with the maximum 15° position estimation error without a magnetic cross-coupling saturation compensation, and nearly zero error with this compensation.

Pole Placement-Based Current Control Method for CSI-Fed PMSM Drive With Eliminating Capacitor Voltage Sampling

This article proposes a pole placement based current control method for the current source inverter (CSI) fed permanent magnet synchronous machine (PMSM) drive with eliminating capacitor voltage sampling. Firstly, a generalized <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$N$</tex-math></inline-formula> -order feedback form of motor current and CSI output current is proposed in the stationary <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\alpha \beta$</tex-math></inline-formula> frame, for the arbitrary pole placement of the control plant. With the proposed pole placement method, the resonance frequency is moved closer to the Nyquist frequency and the resonance peak is damped. On this basis, a linear controller is proposed in the synchronous <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$dq$</tex-math></inline-formula> frame for the high-performance current control of PMSM. Moreover, the control parameter selection method is presented based on the consideration of open-loop crossover frequency and phase margin (PM). In this way, the desired PM and enough gain margin (GM) can be achieved, thus guaranteeing the stability and robustness of the system. Finally, the effectiveness of the proposed method is verified by lab-scaled experiments.

Adaptive Second-Order Active-Flux Observer for Sensorless Control of PMSMs With MRAS-Based VSI Nonlinearity Compensation

This paper proposes an adaptive second-order active-flux observer (ASO-AFO) for sensorless control of permanent magnet synchronous machines (PMSMs) with on-line voltage source inverter (VSI) non-linearity compensation, which is based on the model reference adaptive system (MRAS). First, an ASO-AFO is introduced to observe the active flux. The parameters of the observer are speed-adaptive, thus reducing the observation error in different speed ranges. Then, a method based on MRAS is proposed to compensate the VSI non-linearity. The VSI non-linearity makes the actual voltage different from the ideal output voltage, resulting in a specific harmonic current vector in addition to the fundamental current vector. The fundamental current vector and the current vector composed of the fundamental and harmonic current vectors are selected as the output of the reference model and adaptive model. The cross-product of their output reflects the severity of the VSI non-linearity. The root mean square (RMS) value of the cross-product is selected as the objective function. The non-linearity is compensated by minimizing the objective function, which is realized by the gradient descent method. Finally, the effectiveness of the proposed ASO-AFO with MRAS-based VSI non-linearity compensation is verified by comprehensive experiments.

Multi-dimension SVPWM-based sensorless control of 7-phase PMSM drives

A new control technique for the 7-phase permanent magnet synchronous machine (PMSM) when a failure in the speed sensor is introduced. This will make the whole drive system more robust and at the same time reduce the cost. The speed and the position of the shaft of the motor are obtained by tracking the saturation saliency of the 7-phase motor when a failure in speed sensor is occurred. The proposed saliency-tracking algorithm is based on measuring the derivative of the stator currents of the 7-phase motor after the switching of the insulated gate bipolar transistor (IGBT) of the 7-phase inverter due to the implementation of the multi-dimension space vector pulse width modulation (SVPWM). This modulation technique is used in the 7-phase drives to suppress the 3rd and 5th harmonics. Simulation results show that the 7-phase motor drive could track the reference speed at different load conditions when a failure in the speed sensor is occurred without compromising the performance.

Active Damping Current Control for Current-Source Inverter-Based PMSM Drives

Current-source inverter (CSI) is considered as a promising candidate in the permanent-magnet synchronous machine (PMSM) drive system for its superior current waveforms and inherent capability of withstanding the short-circuit failure. However, the resonance issue is yielded, resulting from the paralleling of machine inductances and filter capacitors. Very limited control bandwidth can be retained if only considering the passive damping of winding resistance. In this paper, the decoupled active damping current controller in the synchronous frame is investigated. The impedance analysis is performed to make a more intuitive demonstration on the damping mechanism, which reveals that the virtual impedance is not always linearly correlated with the damping gain. The digital delay is crucial for the accurate assessment on the damping effectiveness, and the z-domain discrete model is established to emulate the real circumstance. The quantified analysis is performed on deriving the stable boundaries of controller parameters. The frequency responses and root trajectories are illustrated to validate the conclusions. The optimized parameters are obtained by the proposed tuning procedure, which realizes a balance between the damping effect and the bandwidth performance. Finally, the experiments are performed to verify the proposed control schemes.

Fault-Tolerant Predictive Current Control of Six-Phase PMSMs With Minimal Reconfiguration Requirements

By manipulating the additional degrees of freedom of multiphase machines, inherent to this type of machine, fault-tolerant control strategies are able to keep multiphase drives in service after one or more open-phase faults (OPFs). Therefore, multiphase machines controlled by finite control set model predictive control (FCS-MPC) strategies are an excellent fit for critical systems, where reliability and excellent dynamic performance are necessary. However, the existing fault-tolerant FCS-MPC strategies typically require considerable changes to the structure of the control algorithm when transitioning between healthy and fault-tolerant modes of operation. Therefore, this article proposes a novel fault-tolerant predictive current control (FT-PCC) strategy with minimal reconfiguration requirements for the six-phase permanent magnet synchronous machine (PMSM) drives. The proposed method only requires the adjustment of current references during fault-tolerant operation and keeps the structure of the control algorithm unchanged. To validate this FT-PCC strategy, several simulation and experimental results are presented for different OPF scenarios, in which the excellent performance obtained with the proposed method is demonstrated.

Improved Deadbeat-Direct Torque and Flux Control for PMSM With Less Computation and Enhanced Robustness

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 novel digital control scheme for power management in a hybrid energy-source environment pertaining to electric vehicle applications

In electric vehicle, the utilization of various input power sources demand an appropriate integration. This integration inevitably questions the effectiveness of a suitable power management system. The integration of sources causes complexity in power conversion and programming errors while switching between the sources and brings difficulties in real-time implementation. This study presents a novel digital control scheme specific to the integration of solar, battery, and fuel cell to solve these issues and also explains the power management system in different controllers for electric vehicles. The proposed scheme checks the reference currents based on the power generated by the different sources needed to meet the instantaneous demand from the permanent magnet synchronous machine, which is widely used in electric vehicles. The methodology constitutes maximum power point tracking in solar panels at every second of the day, retaining constant voltage in the DC bus and managing the power flow from sources to the permanent magnet synchronous machine based on the power availability from different sources. The power flow to a control module dedicated to permanent magnet synchronous machine control is considered. The major contribution of the paper is the design and development of a power management system for an electric vehicle with a novel digital control scheme. Power management is achieved with the aid of a digital controller using real-time solar data for a periodically fluctuating load demand in MATLAB/Simulink and also in an experimental investigation, the results of which are discussed.

Fault-Tolerant Control of a Dual-Stator PMSM for the Full-Electric Propulsion of a Lightweight Fixed-Wing UAV

The reliability enhancement of electrical machines is one of the key enabling factors for spreading the full-electric propulsion to next-generation long-endurance UAVs. This paper deals with the fault-tolerant control design of a Full-Electric Propulsion System (FEPS) for a lightweight fixed-wing UAV, in which a dual-stator Permanent Magnet Synchronous Machine (PMSM) drives a twin-blade fixed-pitch propeller. The FEPS is designed to operate with both stators delivering power (active/active status) during climb, to maximize performances, while only one stator is used (active/stand-by status) in cruise and landing, to enhance reliability. To assess the fault-tolerant capabilities of the system, as well as to evaluate the impacts of its failure transients on the UAV performances, a detailed model of the FEPS (including three-phase electrical systems, digital regulators, drivetrain compliance and propeller loads) is integrated with the model of the UAV longitudinal dynamics, and the system response is characterized by injecting a phase-to-ground fault in the motor during different flight manoeuvres. The results show that, even after a stator failure, the fault-tolerant control permits the UAV to hold altitude and speed during cruise, to keep on climbing (even with reduced performances), and to safely manage the flight termination (requiring to stop and align the propeller blades with the UAV wing), by avoiding potentially dangerous torque ripples and structural vibrations.

Model Inaccuracy Analysis and Compensation of Stationary Frame-Based Deadbeat Predictive Current Control for High-Speed PMSM Drives

Due to explicit modeling of delay effects and fast dynamic response, the recently reported stationary frame-based deadbeat predictive current control (DBPCC) is particularly attractive for high-speed permanent magnet synchronous machine (PMSM) drives. However, its actual control performances would be heavily dependent on model accuracy. Therefore, this article presents an analytical and systematical investigation into the influences of model inaccuracy on the stationary frame-based DBPCC. Steady-state and transient performance degradations under machine parameter mismatches and inverter nonlinearity over the whole speed range have been studied. Importantly, the analyses show that the steady-state control errors will increase greatly under parameter mismatch as the speed rises; while the transient current tracking errors, only caused by inductance mismatch, can be quickly suppressed after two time-steps. To further improve the parameter robustness of the stationary frame-based DBPCC for high-speed drives, this article also proposes a simple but effective method, called adaptive reference correcting current injection (ARCCI). The proposed method can effectively eliminate all the steady-state current errors caused by model inaccuracy. It can be easily implemented and applicable at high speeds with low switching-to-fundamental frequency ratios (SFRs) as well. Both the presented analyses and compensation methods have been validated by extensive simulations and experiments.

Integration of Interturn Fault Diagnosis and Fault-Tolerant Control for PMSM Drive System

This article first studies the integration of interturn fault diagnosis and fault-tolerant (FT) control of permanent magnet synchronous machine (PMSM) drive system. In this article, interturn fault is diagnosed by zero-sequence voltage component and the torque ripple due to interturn fault is reduced by the current injection-based FT control strategy. The main novelty of this article is that the injection currents for FT control are directly calculated based on the already obtained information during the fault diagnosis process, thus reducing the complexity of FT control and making interturn fault diagnosis and FT control convenient integration. Both the simulation and experimental results validate the effectiveness of the proposed integration method for the PMSM drive system.

Permanent Magnet Synchronous Motor PMSM Control by Combining Vector and PI Controller

In this paper, we present the vector control of a permanent magnet synchronous machine (PMSM) by a PI regulator whose tracking performance; speed, stability, and precision are satisfactory. However, we can see the influence of the variation in the resistance and load torque on the behavior of the controlled system. we analyze the simulation results found and then we make an inventory of PI disadvantages. This work is modified with a novelty by introducing a new control law namely sliding mode and backstepping control law. Then we analyze the results found making a comparison to those of the PI regulator.

Mitigation of Interturn Short-Circuits in IPMSM by Using MTPCC Control Adaptive to Fault Severity

Incipient interturn short-circuits (ITSCs) in permanent-magnet synchronous machines (PMSMs) develop to direct short-circuit without proper mitigation. This article proposes an ITSC mitigation control for standard three-phase interior PMSMs (IPMSMs) driven by typical three-phase inverters, named as maximum torque per circulating current (MTPCC), to constrain the circulating current (CC) due to ITSC within acceptable limits so as to delay the insulation degradation between shorted turns, and to maximize output torque to support the postfault performance. In the <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$dq$</tex-math></inline-formula> current plane, it is shown that for a specific fault severity and machine speed, the operating points with the same CC form a circle, and for constant torque with ITSC is a hyperbola. ITSC is a fast-developing fault that implies the fault severity continues to increase with time, and the positions of the CC circle and torque hyperbola change with the increasing fault severity in the <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$dq$</tex-math></inline-formula> current plane. The MTPCC control updates the mitigation operating point automatically, depending on the positions of the CC circle and torque hyperbola with respect to the circle of the machine's maximum current, to produce the maximum possible torque as the fault severity changes, which shows that it is adaptive to the variation of fault severity. The proposed mitigation control is validated through experiments.

Novel Deadbeat Predictive Current Control for PMSM With Parameter Updating Scheme

Deadbeat predictive current control (DPCC) has been employed for permanent magnet synchronous machines (PMSMs) due to its satisfactory steady-state and dynamic performances. However, dependence on the accuracy of parameters is a major barrier for its widespread application. To address this problem, a novel control method that can update related items with internal parameters online, in which winding resistance, flux linkage, and stator inductance are considered simultaneously, is proposed in this article. First, the current prediction errors in the <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$d$ </tex-math></inline-formula> -axis and <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$q$ </tex-math></inline-formula> -axis are analyzed and stored. It has to be mentioned that the extended Kalman filter (EKF) is applied to filter the measured current and optimize the estimated current. Second, through the error of two consecutive control periods, the related items can update in real time. Finally, an updating mechanism based on DPCC is established to control the drive system. Since only measured current is used in the control system, the proposed algorithm is easy to implement. The simulation and experimental results indicate the effectiveness of the proposed method under complex parameters mismatch conditions.

Model-Free Sliding Mode Control for PMSM Drive System Based on Ultra-Local Model

This paper presents a novel model-free sliding mode control (MFSMC) method to improve the speed response of permanent magnet synchronous machine (PMSM) drive system. The ultra-local model (ULM) is first derived based on the input and the output of the PMSM. Then, the novel MFSMC method is presented, and the controller is designed based on ULM and MFSMC. A sliding mode observer (SMO) is constructed to estimate the unknown part of the ULM. The estimated unknown part is feedbacked to MFSMC controller to perform compensation for parameter perturbations and external disturbances. Compared with the sliding mode control (SMC) method, the results of simulation and experiment demonstrate that the presented MFSMC method improves the dynamic response and robustness of the PMSM drive system.

Field oriented control of PMSM drive with backup power supply

The primary purpose of the article is to examine the field oriented control system of permanent magnet synchronous machine (PMSM) electric drive with backup power supply. Authors propose to use bi-directional DC-DC converter to ensure the «hot» backup operation mode in case of grid fault. The change-over switching system, which provide transfer of voltage-source inverter (VSI) from DC link to the backup power source is considered. The presented system provides a good dynamic transient process; the results are confirmed by simulation in Psim software. Moreover, based on the results acquired, an electric drive based on PMSM with field oriented control and a backup power supply system from the battery via a bi-directional DC-DC converter is capable of operating according to the principles of «hot» backup.

Low-Complexity Deadbeat Model Predictive Current Control for Open-Winding PMSM Drive With Zero-Sequence Current Suppression

The application of model predictive current control (MPCC) on the open-winding permanent magnet synchronous machine (PMSM) drive system confronts the challenge of complexity due to the enumeration process and the multiobjective cost function evaluation. In this article, a new low-complexity MPCC is proposed to eliminate the online enumeration process and the cost function evaluation. In the proposed scheme, the reference voltage vector components are calculated based on the deadbeat principles. Then, the optimal voltage vector that matches the reference vector is selected from the control set based on predefined optimization criteria. These criteria are defined offline by solving the conventional current control cost function in the 3-D ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\alpha $ </tex-math></inline-formula> – <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\beta $ </tex-math></inline-formula> – <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$z$ </tex-math></inline-formula> ), utilizing new 3-D analysis. The proposed control scheme is compared with the conventional finite control set (FCS)-MPCC and the existing 3-D-MPCC schemes using MATLAB simulation and hardware-in-the-loop (HIL) results. Compared with conventional FCS-MPCC and 3-D-MPCC schemes, the proposed control scheme presents the same salient features, such as fast dynamic response, low output current/torque ripple, and zero-sequence current suppression. The computational complexity of the proposed control scheme is much lower than the conventional FCS-MPCC.

Multiple reference frame-based current harmonic control for interior PMSMs considering motional EMF

For permanent magnet synchronous machines (PMSMs), current harmonics need to be controlled under two kinds of conditions. Under the first condition, the current harmonics caused by the non-sinusoidal back-electromotive force (EMF) and the dead time of inverters should be suppressed. Under the second condition, specific current harmonics should be injected to suppress the torque ripple of motors. Therefore, the accurate control of current harmonics is critical. It has been found that the original multiple reference frame (MRF)-based control algorithm cannot effectively achieve the control of current harmonics at high speeds. For the currents in MRFs, motional EMF was dominant rather than induced EMF at higher speeds. As a result, the original MRF-based control algorithm does not work at high speeds. To solve this problem, this paper proposed a novel MRF-based control algorithm that considers motional EMF. Furthermore, this paper achieved decoupling control of the current harmonics in MRFs for interior PMSMs. With the proposed control algorithm, the current harmonics of interior PMSMs can be controlled at both high and low speeds. Under the influence of non-sinusoidal back EMF and the dead time of the inverter, the effect of current harmonic control was verified on a laboratory test bench.

Compensation of Selective Current Harmonics for Switching-Table-Based Direct Torque Control of Dual Three-Phase PMSM Drives

Current harmonics are ubiquitous in dual three phase (DTP) permanent magnet synchronous machine (PMSM) drives. Due to back electromotive force (EMF) distortion, significant current harmonics are generated in the DTP-PMSM system. The influence of back EMF harmonics is investigated in this paper and a novel switching-table-based direct torque control method to compensate the selected current harmonics caused by the back EMF harmonics is proposed. It shows that by employing different optimal action time durations for voltage vectors in the z <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1</sub> z <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> subspace and setting the synthetic voltage vectors to non-zero, the stator flux harmonics caused by the back EMF harmonics can be selectively compensated, as verified by experiments.

Model Predictive Torque Control for Dual Three-Phase PMSMs with Simplified Deadbeat Solution and Discrete Space-Vector Modulation

Unprecise voltage vectors applied in conventional model predictive control (MPC) would cause additional ripples in electromagnetic torque. To eliminate the problem, this article proposes an improved model predictive torque control (MPTC) based on deadbeat solution and discrete space-vector modulation (DSVM) for dual three-phase permanent magnet synchronous machines (PMSMs). First, deadbeat-direct torque and flux control (DB-DTFC) algorithm is applied and simplified, so that the computational burden can be reduced. Second, the virtual voltage vectors (VVVs) are adopted in dual three-phase voltage vector space to reduce voltage harmonics. Also, the DSVM is further proposed in this VVVs based vector space to generate more voltage vectors. After that, the simplified DB-DTFC and the DSVM scheme are artfully combined to select suitable voltage vector candidates for the MPTC, and the best one is then chosen to control the dual three-phase PMSMs. Finally, both simulation and experimental results are given to verify the effectiveness of the proposed method.