Winding Permanent Magnet Synchronous Motor Research Articles

Analysis of low saliency ratio and torque characteristics of the fractional slot concentrated winding surface mounted motors

In recent years, fractional slot concentrated winding permanent magnet synchronous motors (FSCW PMSMs) have become a hotspot in the research field. Due to the unique inductance characteristics of the FSCW PMSM, a fast and accurate calculation of the d/q-axis inductance and saliency ratio is necessary. In this paper, a method is proposed to calculate the d/q-axis reactance of the FSCW SPMSM, which constructs the equivalent magnetic circuit model of the d/q-axis armature reaction flux separately, and the saliency ratio characteristics of the FSCW SPMSM were demonstrated. In addition, to meet the high requirements of the modern industries, especially in servo systems, accurate consideration of the effect of stator resistance on torque and electromagnetic performance is important and more applicable. According to the relationship between the vector parameter, the explicit expression of the d/q-axis currents that consider the stator resistance is obtained, and the prediction of load angle at maximum electromagnetic torque is achieved. Then, combined with the finite element method, the influence mechanism of stator resistance on the motor steady-state performance is revealed. Finally, the experimental data are compared with the calculation data, and the correctness of the models and analysis was verified.

The Torque Elimination Control Strategy for Integrated Dual-Battery Charger of Electric Vehicle based on Open-End Winding Permanent Magnet Synchronous Motor

The Torque Elimination Control Strategy for Integrated Dual-Battery Charger of Electric Vehicle based on Open-End Winding Permanent Magnet Synchronous Motor

A Novel Winding Connection Sequence of Dual Three-Phase Series-End Winding PMSM Drive for Speed Range Extension

Series-end winding motor drives double the dc-link voltage utilization compared with the conventional star-connected winding counterparts, which indicates that series-end winding motor drives are suitable for high-speed applications with limited dc-link voltage. To further improve the dc-link voltage utilization and extend the speed range of the dual three-phase series-end winding permanent magnet synchronous motor (DTSW-PMSM) drive system, this paper proposes a novel winding connection sequence (WCS) for DTSW-PMSM drive, and the dc-link voltage utilization is further improved by 36.6% compared with the normal WCS. The dc-link voltage utilizations of different WCSs are analyzed through the phasor relationship between the phase and leg voltages. Besides, the corresponding carrier-based pulse-width modulation to drive the DTSW-PMSM with the proposed WCS is also developed. In the experimental tests, the speed range of the DTSW-PMSM drive with the proposed WCS is extended significantly. Therefore, adopting the proposed WCS can be an effective means for further speed range extension of DTSW-PMSM drives without additional hardware.

An Optimized Modulation for Five-Phase Open-End Winding PMSM With Sliding Clamped Strategy

Five-phase open-end winding permanent magnet synchronous motor (OEW-PMSM) fed by a dual inverter has gained increasing focus because of its advantages in voltage utilization, torque density and reliability. In this paper, an optimized modulation method with the sliding clamped strategy is proposed for the five-phase OEW-PMSM drive with a common DC bus. The conventional clamped strategies have a reduced switching sequence. However, the clamped inverter generates the zero-sequence voltage and third harmonic voltage, which would affect the performance of the motor. To solve this problem, the reference voltages in the proposed method are distributed by limiting the reference voltage of the clamped inverter on a line. And the reference voltage slides on this line bidirectionally. Therefore, the clamped inverter in the proposed method will not introduce additional harmonic components. For experimental verifications, the test results are presented with the resistance-inductance load and five-phase OEW-PMSM.

An Open-Circuit Fault Detection Method of PMSM Fed by Dual Inverter With High Robustness

Power semiconductor is one of the most fragile components in the drive system of electric vehicles. In order to diagnose the failure timely, this paper proposes a diagnosis method of the open-circuit fault for open-end winding permanent magnet synchronous motor (OEW-PMSM) fed by dual inverter with a single dc source. The OEW- PMSM can improve the speed range and tolerance capacity of driving systems. However, the open-circuit fault diagnosis methods for Y-connected PMSMs cannot judge the faulty switch because of the symmetry of the dual inverter structure. The first step of the proposed method is to detect the faulty switch combinations by the error of normalized average value and average value of the zero-sequence reference voltage. The next step is to judge the faulty switch from a certain fault combination. The experimental results show that the open-circuit fault can be diagnosed accurately.

Multivector-Based Model Predictive Current Control With Zero-Sequence Current Suppression for Three-Phase Series-End Winding Permanent Magnet Synchronous Motor Drives

To suppress the zero-sequence current and enhance the steady-state performance of the three-phase series-end winding permanent magnet synchronous motor (TPSW-PMSM) drives, a multi-vector-based model predictive current control scheme with zero-sequence current suppression is developed in this paper. The concept of the desired voltage is utilized to preselect the candidate voltage vectors and offer the guidance of the geometric division of the sector. In one sampling period, multi-voltage vectors are employed, and the combinations include one active voltage vector and one null voltage vector, and two active voltage vectors, which improves the steady-state performance. Meanwhile, the duty cycle of each voltage vector is derived based on an intuitive geometric expression of the cost function. Further, the relationship between the zero-sequence voltage injection and the switching sequence is revealed, and it is employed to suppress the zero-sequence current actively. In addition, overmodulation operation is also taken into consideration in the proposed scheme. Finally, the experimental study validates the effectiveness of the proposed scheme.

A Weighting-Factorless Predictive Torque Control Method for Open-End Winding PMSM with Common DC Bus

The weighting factors (WFs) of conventional predictive torque control (PTC) are difficult to tune, which limits its practical application. When the conventional PTC is applied to the open-end winding permanent magnet synchronous motor (OEW-PMSM) with a common DC bus, there are three different units of variables that require prediction and control. Therefore, it is necessary to introduce two WFs to construct the cost function (CF), which increases the difficulty of realizing the control strategy. Sequential PTC adopts the idea of hierarchical optimization to avoid the introduction of WFs directly. In this paper, the sequential PTC structure is constructed to avoid the introduction of WFs. Then, the number of elements in the finite control set (FCS) of each layer is optimized to reduce torque and zero sequences current (ZSC) ripple, so as to achieve a better control effect. Finally, the effectiveness of the proposed sequential control strategy is proved by simulation.

High Frequency Torque Pulsation Suppression Strategy for Dual Winding Permanent Magnet Synchronous Motor Sensorless Control Based on Dual High Frequency Square Wave Injection Method

High Frequency Torque Pulsation Suppression Strategy for Dual Winding Permanent Magnet Synchronous Motor Sensorless Control Based on Dual High Frequency Square Wave Injection Method

Research on Novel Flat Wire Transposed Winding of PMSM for Electric Vehicle

Permanent magnet synchronous motor (PMSM) for electric vehicles is developing higher frequency and speed but triggering a significant increase of eddy current loss. To resolve the eddy current loss issue, a novel flat wire transposed winding composed of double-row multiple parallel strands is proposed. Transposed winding techniques have been proved to be efficient in reducing eddy current loss by preventing the uneven leakage magnetic field induced by high frequency. The proposed transposition further improved this technique in reducing circulating current loss. Taking a 60-kW PMSM as an example, the novel flat wire transposed winding arrangement is carried out. The 3-D field-circuit coupled finite-element models of 360° complete transposed and incomplete transposed winding PMSM are established, and circulating current losses are compared. The analysis results show that incomplete transposed winding has a better performance in reducing the circulating current loss. The transposition method suitable for novel flat wire transposed winding is obtained, and the feasibility of PMSM with novel flat wire transposed winding to reduce winding losses is proven.

A Simplified Predictive Current Control of Open-End Winding Permanent Magnet Synchronous Motor

Model predictive current control (MPCC) of a 4-level inversion fed open-end winding permanent magnet synchronous motor (OEW-PMSM) using 37 voltage vectors (VV) suffers from the disadvantage of the increased computation burden. A high computation burden on the processor puts a limit on the selection of the minimum sampling time. In this article, a novel method is presented for reducing the computation burden. The proposed method reduces the number of candidate VVs from 37 to a maximum of 4 and a simple cost function is proposed to select the optimal VV. The proposed method calculates the change in stator current (CSC) needed to obtain the required change in the stator flux. The CSC vector is in the direction of the required change in the stator flux, which is used to shortlist the candidate VV for the reduced control set. The required change in the flux is obtained using the reference stator current of the next sample. The multiple predictions of the <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">d-q</i> currents are eliminated and a simple cost function based on the difference between per-unit CSC and candidate VV is used to simplify the calculations. The proposed method is experimentally tested and compared with existing MPCC. The results confirm the effectiveness of the proposed scheme.

Clamping Modulation Technique for Balancing Power Losses of Dual Inverter With Isolated DC Bus

This paper proposes a clamping modulation technique to reduce and balance power losses in a dual inverter with an isolated DC bus. To drive an open-end winding permanent magnet synchronous motor (OEW-PMSM), dual inverter consisting of six legs has twelve switching actions, twice as many as a two-level voltage source inverter (VSI) per switching period. However, many switching actions cause power losses in switching devices, reducing the efficiency of the system. In this paper, a four-leg clamping modulation technique is presented to reduce the switching actions by analyzing the relationship between two reference voltage vectors of primary and secondary inverters on a space vector plane. To clamp four of the six legs overall, the switching states are determined by combining active and zero vectors during the switching period. The selected vector combinations differ according to 18 sectors divided by the magnitude and angle of the reference voltage vector. The zero vectors required for 18 sectors are then distributed to balance the power losses in upper and lower switching devices of each leg. This technique is implemented with carrier-based pulse width modulation (PWM) by calculating each three-phase reference voltage from two reference voltage vectors composed of the vector combinations. Balancing of the power loss between the upper and lower switching devices is achieved by adding offset voltages corresponding to the zero vector of each sector. The validity of the proposed technique is verified experimentally.

Control of PMSM Drive Using Lookup Table Based Compensated Duty Ratio Optimized Direct Torque Control (DTC)

There are several ways to reduce the ripple magnitude for direct torque-controlled permanent magnet synchronous motor (PMSM) drives. In this work, the compensated duty ratio optimized direct torque control (DDTC-TC) method was proposed to reduce the ripple for three-phase PMSM. The proposed control strategy employs the simplicity of conventional DTC (CDTC) and compensation of the reference torque to enforce the developed torque to oscillate around the required value. A torque error square minimization technique is employed to determine the duty ratio. The magnitude of the developed torque by the PMSM depends on the torque slope during the active and null voltage periods. The slope of the torque during each period is computed online. Based on the online computed slopes, the magnitude of the switching period and compensation torque were calculated. The ripple reduction capability of the proposed control scheme is tested using Matlab Simulink and a hardware in loop system. Results indicate that the control scheme is effective. Specifically, the torque and speed ripples are very small. The torque ripple during speed fluctuation is less for open-end winding PMSM. In addition, the proposed scheme is tested for four-quadrant operation, and the scheme is effective for four quadrant operation. Finally, verification of the effectiveness of the proposed scheme is performed using OPAL-RT-RT (OP4500). Verification indicates that the proposed scheme is effective.

Self-Adapted Model Predictive Current Control for Five-Phase Open-End Winding PMSM With Reduced Switching Loss

This article proposed a self-adapted model predictive current control (SA-MPCC) method to reduce the switching loss of the five-phase open-end winding permanent-magnet synchronous motor (OW-PMSM). The proposed SA-MPCC method regards the OW-PMSM drive system as two separate parts by utilizing the flexibility of the OW-PMSM system, thus generating and applying the phase voltage to armature winding independently. The virtual voltage vectors and multivector duty cycle modulation strategy is adopted to maintain a good steady-state and dynamic behavior. Then, the self-adapted decision is generated to choose one inverter work solely, or two inverters work cooperatively. When one inverter is used, another inverter is closed. The first inverter is clamped to optimal virtual voltage vectors when two inverters work together. The clamping to virtual voltage vectors or zero vectors can reduce the switching loss in both sides of the dual inverter. Finally, the experimental results verify the effectiveness of the proposed SA-MPCC method.

A Novel Open-Circuit Fault Detection and Location for Open-End Winding PMSM Based on Differential-Mode Components

Detecting and locating the open-circuit (OC) fault of an insulated-gate bipolar transistor (IGBT) rapidly and accurately is very important to improve the security and reliability of the drive system. However, due to the symmetry of the dual-inverter topology, it is difficult to achieve fault detection for open-end winding permanent magnet synchronous motor (PMSM). Thus, this article proposes a fault diagnosis technology for open-end winding PMSM fed by a dual inverter with a common dc bus. In this method, the faulty phase and the faulty case are identified by the average value of the output of the closed-loop controller, which is used to eliminate the differential-mode current in the system. Then, the faulty phase is isolated by removing the gate signals. Finally, the faulty IGBT is located by restructuring the faulty phase and analyzing the current of the faulty phase. In this method, the OC fault can be detected and the faulty IGBT can be located accurately. Experimental results are shown to validate the proposed detection method.

Common-Mode Voltage Suppression Technique for Open-End Winding PMSM System With Five Bridge Arms

To further improve the reliability of the open-end winding permanent magnet synchronous motor (OW-PMSM) and avoid the secondary damage caused by the common-mode voltage (CMV) in the event of bridge-arm failure, a CMV suppression technique is proposed. With the proposed technique, the reference voltages in three-phase stationary coordinate system are optimized to adapt the characteristics of OW-PMSM with five bridge arms. Further, an improved modulation scheme is proposed, in which the CMV is suppressed and the switching actions within every control cycle is reduced. The effectiveness of the proposed technique is validated through experimental results.

Self-Sensing Control of Open-End Winding PMSMs Fed by an Asymmetrical Hybrid Multilevel Inverter

The paper presents a self-sensing control technique for a special type of multilevel motor drive featuring an Open-end Winding Permanent-Magnet Synchronous Motor fed on one side by a main multilevel inverter (MLI) and on the other side by an auxiliary two-level inverter (TLI). In order to minimize the power losses, the MLI manages the machine active power operating at a low-switching frequency. The TLI instead acts as an active power filter and operates at a higher switching frequency and a lower DC-Bus voltage than the MLI. The current control task is shared between the two inverters, as a predictive action is exerted by the MLI, while a feedback action is accomplished by the TLI. Common sensorless rotor position estimation techniques cannot be straightforwardly applied on such a system, due to the particular drive structure. Therefore, a specific technique has been carried out, able to ensure satisfactory efficiency and control performance in all the operating speed ranges by optimally exploiting the different features of the two inverters. Simulation and experimental results confirm the effectiveness of the proposed approach.

Dual-Vector Predictive Current Control of Open-End Winding PMSM With Zero-Sequence Current Hysteresis Control

Dual-inverter fed open-end winding permanent magnet synchronous motor (OW-PMSM) drive topology can extend the speed range under limited dc bus voltage, but it suffers from the zero-sequence current (ZSC) problem when with common bus configuration. Predictive current control (PCC) is a potential high-performance control method for electric drive. However, the PCC algorithm for dual-inverter system may bring a huge computational burden because of more space vectors (SVs) to traverse. In order to improve the steady-state current performance and suppress the ZSC, this article proposes a dual-vector PCC (DV-PCC) method for OW-PMSM with ZSC hysteresis control. The reference voltage vector is predicted in advance according the model. A novel sector judgment method is used to judge the sector and subsector where the reference voltage vector is located, and determines the two candidate SVs. Then the dwell time of the two candidate SVs is calculated through the projection length of the reference voltage vector. Moreover, the switching states redundancy feature of dual-inverter system is employed to suppress ZSC. As some SVs correspond to multiple switching states of different zero-sequence voltages (ZSVs), the switching state whose ZSV polarity is opposite to the ZSC polarity is selected as the output to realize the hysteresis control of ZSC. When the ZSVs of the candidate SVs contradict the hysteresis control demand, the zero-vector insertion method is used to guarantee the effective suppression of ZSC. The experiments are implemented in comparison with the existing DV-PCC method.

A New IPMSM With Hybrid Rotor Structure for Electrical Vehicle With Reduced Magnet Loss

Aiming at the problem of excessive eddy current loss of permanent magnets in fractional slot concentrated winding permanent magnet synchronous motors (FSCW-PMSM) at high speed, a new PMSM with hybrid rotor structure for electric vehicles (EV) is proposed in the article, the key is to introduce additional ferrite magnets in <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> - 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 magnetic flux paths, respectively. Furthermore, slotting on the rotor surface and genetic algorithm (GA) optimization are adopted to compensate for the side effects caused by the introduction of ferrite magnets and to obtain optimal parameters of the new motor. Compared with the traditional all-Nd-Fe-B structure, the proposed hybrid rotor structure can not only curb the magnet loss at high speed, but also present a cost-effective design approach for interior pemanent magnet synchronous motor (IPMSM) for EV applications with less usage of expensive Nd-Fe-B magnets as well as enhanced reluctance torque capability.

Five-Level Hysteresis DTC of Open-End Winding Permanent Magnet Synchronous Motors With Zero-Sequence Currents Suppression and Torque Ripple Reduction

Direct torque control (DTC) systems for open-end winding permanent magnet synchronous motors (OEW-PMSM) with common DC bus generate zero sequence currents (ZSC) and large torque ripple, resulting in increased system loss and poor operating characteristics. In this paper, a DTC based on five level torque hysteresis (FLTH) is proposed to improve the system performance. Firstly, an online calculation and selection strategy based on switch table is designed to suppress ZSC. By analyzing the composition of zero sequence voltage and using the double vector method to suppress it, the ZSC can totally be suppressed in theory, without affecting the system performance. On this basis, this paper proposes to add FLTH to DTC to reduce torque ripple. FLTH can not only effectively use many voltage vectors, but also reduce torque ripple. In the case study, the torque ripple rate has been reduced by 53%. Through simulation and experiment, the conventional DTC and the FLTH DTC are compared, and the results prove the validity of the proposed strategy.

Three-Dimension Space Vector Based Finite Control Set Method for OW-PMSM With Zero-Sequence Current Suppression and Switching Frequency Reduction

The zero-sequence current (ZSC) of open-end winding permanent magnet synchronous motor (OW-PMSM) with common dc bus mainly comes from zero-sequence voltage (ZSV) and third harmonic back electromotive force, so the ZSV levels of voltage vectors in model predictive control (MPC) need to be considered to suppress the ZSC. Different from the conventional MPC methods for OW-PMSM, which usually select the optimal voltage vector under αβ0 coordinate system, this article proposes a three-dimension space vector (TDSV) based MPC method under ABC three-phase coordinate system for OW-PMSM with ZSC suppression and switching frequency optimization strategy. Benefiting from the three-phase voltages decoupling feature of OW-PMSM, TDSVs in ABC coordinate system are regularly distributed in a space cube. A simple optimal TDSV selection method is proposed based on subcubes division. TDSV contains the predicted α-,β-,0 -axis voltages information, so ZSC suppression is achieved automatically. Furthermore, utilizing the switch states redundancy feature of dual-inverter system, a cost function is designed to optimize the switch states change and reduce the switching frequency without affecting the optimal TDSV selection. The performance and switching frequency reduction effect of the proposed method are verified and compared with the existing methods through experiments.