Open-winding Permanent Magnet Synchronous Machine Research Articles

Novel SVPWM for Open Winding PMSM Drives With Simultaneous Common Mode Voltage Control and Full Frequency Zero Sequence Current Suppression

Zero sequence voltage (ZSV) can cause zero sequence current (ZSC), while variation of common mode voltage (CMV) can cause bearing current in an open winding (OW) permanent magnet synchronous machine (PMSM) fed by common dc -bus dual two-level inverters. This article proposes a novel space vector pulsewidth modulation (SVPWM) strategy for simultaneously eliminating CMV variation and suppressing full frequency ZSC harmonics in either linear or over modulation region by optimal selection of switching combinations. The proposed SVPWM can reduce large ZSV ripples and number of switching actions in the conventional CMV control method for the common dc -bus OW drive. Thus, high-frequency ZSC harmonics and switching frequency can be significantly reduced in both linear and over modulation regions. Moreover, the proposed SVPWM can suppress large low-frequency ZSC harmonics induced by the conventional method in over modulation region. The superior performances of CMV variation elimination and full frequency ZSC suppression in the proposed SVPWM are verified by experiments.

An improved power balancing control scheme for open‐winding permanent magnet synchronous machine based on redistribution of reference voltages

In open-winding permanent magnet synchronous machine (OW-PMSM) applied in electric vehicular system, two voltage sources composed of battery packs are applied. For safety and better performance, the over-discharge on one of these two voltage sources should be avoided and their state of charges (SOCs) should be controlled in balance. On this basis, a reference voltage redistribution-based control scheme is proposed to balance the SOCs of OW-PMSM system in this letter, which utilizes the SOCs of the two voltage sources to distribute the reference voltages into two inverters. With the proposed method, the SOCs of the two voltage sources can be controlled in balance dynamically, while the synthesis of the reference voltage is not affected. The performance of the proposed method is validated experimentally.

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.

Model Predictive Two-Target Current Control for OW-PMSM

Open-winding permanent magnet synchronous machine (OW-PMSM) could obtain the higher bus voltage utilization and more robustness against the component damage and faults. However, the additional torque ripples and total harmonic distortion (THD) caused by zero-sequence current would limit the further applications of OW-PMSM. In this article, a novel model predictive two-target current control (MPTCC) scheme is presented to deal with such problem through model predictive control concept. First, a basic model predictive current control is proposed to deal with the torque production in fundamental components. Then, another modified cost function is proposed to provide more precise voltage vectors in torque production. After that, the deadbeat predictive control concept is proposed to calculate the required voltage vectors in zero-sequence loop. This zero-sequence voltage is injected in the voltage vectors, which are responsible for torque production. It needs to be mentioned that the limitation of inverter is analyzed. And the real-time judgment is proposed to assess the performance of MPTCC in some work conditions. Finally, both simulation and experiments have been both applied to assess the performances of the proposed control scheme. Comparing with those existing q-axis current injection methods and modified space vector pulse width modulation (SVPWM) technologies, the proposed control scheme could eliminate the torque ripple and THD at the same time and thus possess the better performances.

Fault‐tolerant control strategy with reduced switching frequency for inverter‐based fault in open‐winding PMSM system

The open-winding permanent magnet synchronous machine (OW-PMSM) system is widely investigated for its potential fault tolerance while extra switching loss is inevitable due to the doubled switch devices. Hence, to further improve its performance, a fault-tolerant control strategy against the inverter-based fault, in which the corresponding terminal of the phase winding is connected with the mid-point of the two capacitances in parallel to the dc voltage, is proposed in this Letter. In the proposed method, the reference voltages are modulated under the three-phase stationary coordinate system, considering the voltage fluctuation of the capacitances. In addition, to reduce the switching frequency, the reference voltages are adjusted synchronously, according to the polarity of the reference voltages. Moreover, the effective modulation range of the proposed method is analysed. Finally, the performance of the proposed strategy is validated experimentally.

A Novel Zero-Sequence Current Elimination PWM Scheme for an Open-Winding PMSM With Common DC Bus

This paper introduces a novel pulsewidth modulation (PWM) scheme for an open-winding permanent magnet synchronous machine (OW-PMSM) driven by dual two-level three-phase inverter with common dc bus, which can effectively deal with the inherent zero-sequence current (ZSC) problem. Based on the conventional symmetrical unipolar double-frequency sinusoidal PWM scheme with an appropriate phase shift, the common mode voltage (CMV) of two inverters remains same and cancel out each other to eliminate the modulated zero-sequence voltage (ZSV) disturbance source. In this case, the double-frequency effect can be retained to reduce the ac side current ripple and suppress both corresponding motor vibration and acoustic noise, which is advantageous to improve the synthetic performance of motor. The dc-bus voltage utilization of the novel PWM scheme is proved to reach the same maximum value comparing to the conventional modulated ZSV elimination scheme. Meanwhile, a zero-sequence controller is designed to suppress ZSC by further adjusting the two CMVs to counteract other zero-sequence disturbance sources. To verify the analysis, the proposed PWM technique associated with the control method is implemented in an OW-PMSM experimental setup to validate the superiority of the proposed method.

Torque Ripple Suppression Method With Reduced Switching Frequency for Open-Winding PMSM Drives With Common DC Bus

Torque ripple caused by zero-sequence current (ZSC) and relatively high switching frequency severely worsens the operating performance of an open-winding permanent-magnet synchronous machine (OW-PMSM) system with common dc bus. In this paper, a novel q -axis current injection method based on the angle-shift-based voltage distribution is proposed for the OW-PMSM system with common dc bus. With the proposed method, torque ripple caused by ZSC can be counteracted by the torque component generated by the injected q -axis current. Meanwhile, the corresponding modulation range is analyzed to investigate the availability of the proposed method. Moreover, in order to reduce the switching frequency, zero vector (111) is no longer necessary to compensate the zero-sequence component and conventional space vector pulsewidth modulation (PWM) with zero vectors (000) and (111) can be simplified. The switching actions in one PWM period can be reduced from 12 to 8. The comparison of losses shows that this strategy can effectively improve the efficiency under both heavy load and high switching frequencies. Finally, the effectiveness of the proposed method is validated through an OW-PMSM experiment with common dc bus.

Analysis and Suppression of Zero Sequence Circulating Current in Open Winding PMSM Drives With Common DC Bus

In this paper, the zero sequence circulating current in open winding permanent magnet synchronous machine (OW-PMSM) drives with common dc bus is systematically analyzed for the first time. It is revealed that the zero sequence circulating current is affected by zero sequence back-electromotive force, cross coupling voltages in zero sequence from the machine side, pulse-width modulation induced zero sequence voltage, and inverter nonlinearity from the inverter side. Particularly, the influences from the cross coupling voltages in zero sequence and parasitic effect of inverter nonlinearity are investigated for the first time in this paper. Then, the synthetic model of the equivalent zero sequence circuit is proposed as well. Each cause is studied independently via analytical modeling, finite element analysis, and experiments. Meanwhile, to tackle this issue, the relevant suppression strategy using frequency adaptive proportional resonant controller is presented and tested on the 3 kW OW-PMSM platform.

A Novel Zero-Sequence Model-Based Sensorless Method for Open-Winding PMSM With Common DC Bus

This paper proposes a zero-sequence model-based sensorless control strategy for open-winding permanent-magnet synchronous machine (OW-PMSM) with common dc bus. The third harmonic back electromotive force (EMF) in zero-sequence is utilized to estimate the rotor position information. The novelty is that the third harmonic back EMF is reconstructed based on the zero-sequence model together with zero-sequence current, instead of using voltage transducer and three phase resistance network which can be eliminated from the control system. Due to the essence of back EMF, the developed method is appropriate for the applications including wind power generation and motor drives operating above certain speed. Meanwhile, the phase shift-based space vector pulse width modulation method for OW-PMSM is also presented for easier implementation to form zero voltage disturbance in zero-sequence from the inverter side and hence the corresponding influence can be consequently minimized. The torque ripple, loss, and parameter sensitivity analysis are also carried out, as confirmed by predictions of two-dimensional finite element analysis. Due to the essence of decouple, the estimation can be more robust than the conventional fundamental model-based sensorless methods. Finally, the effectiveness of the proposed method is validated experimentally on a 3-kW OW-PMSM drive system with 2.5 kg·m2 total inertia.