Explore the vast range of titles available.

Current harmonics in six-phase permanent magnet synchronous motors (PMSMs) arise from inherent asymmetries caused by manufacturing tolerances and nonlinear characteristics in the inverter output. Additionally, magnetic saturation and slight imbalances in the windings introduce flux linkage asymmetries, resulting in both fundamental current imbalance and low-order harmonics. Although these imbalances are minor and do not indicate fault conditions, they can cause uneven copper loss and eventually reduce the overall service life of the motor. This paper proposes a harmonic suppression strategy for mitigating imbalance current harmonics in non-ideal six-phase PMSMs. The method integrates back-electromotive force harmonic feedforward compensation (BEMF-HFC) with harmonic synchronous reference frame current control (HSRF-CC). An imbalance flux linkage harmonic model is developed in simulations to replicate the measured imbalance phase currents and to validate the effectiveness of the proposed strategy. The experimental setup is built using a microcontroller from Texas Instruments (TI), which generates six-phase complementary PWM signals for the power stage and receives feedback signals including phase currents, DC bus voltage, and rotor position. Rotor position is acquired through a 12-pole resolver and a 12-bit resolver-to-digital converter (RDC). The six-phase PMSM used in the tests is specified with 12 poles, a rated DC bus voltage of 600 V, a rated current of 200 Arms, and a rated rotor speed of 1200 rpm. Compared with conventional harmonic suppression strategies that do not target imbalance current harmonics, the proposed method achieves a better current balance and lower total harmonic distortion (THD). At 1200 rpm, the magnitude deviation of the fundamental, third, and fifth current harmonics is reduced from 8.61%, 2.88%, and 2.94% to 1.19%, 1.02%, and 0.5%, respectively.

This paper proposes a current harmonic suppression strategy that combines harmonic synchronous rotating frame (HSRF) current feedback control and back-electromotive force harmonic (BEMFH) feedforward compensation to suppress the fifth and seventh current harmonics of a six-phase permanent magnet synchronous motor (PMSM). The current harmonics of six-phase PMSMs vary with the current due to manufacturing imperfections and the inverter nonlinearity effect. Using fixed-parameter BEMFH feedforward compensation cannot completely eliminate current harmonics. This paper integrates a closed-loop harmonic current control strategy, using HSRF in the differential mode of the six-phase PMSM rotor rotating frame to effectively mitigate current harmonic variations caused by load changes. The controller adapts a Texas Instrument microcontroller featuring encoder interfaces, complementary pulse width modulation (PWM), and analog–digital converters (ADC) to simplify the board design. The rotor angle feedback is provided by a 12-pole resolver in conjunction with an Analog Device resolver-to-digital converter (RDC). The specifications of the six-phase PMSM are as follows: 12 poles, 1200 rpm, 200 A (rms), and 600 V DC bus. The total harmonic distortion (THD) of the phase current for harmonics below the 21st order was reduced from 31.71% to 4.84% under the test conditions of 1200 rpm rotor speed and 200 A peak phase current. Specifically, the fifth and seventh harmonics were reduced from 29.98% and 9.72% to 2.74% and 1.21%, respectively. These results validate the feasibility of the proposed current harmonic suppression strategy.

When the interior permanent magnet synchronous motor (IPMSM) is running, there are abundant harmonics in the stator current. In order to achieve the suppression of current harmonics, the current harmonic extraction method and current harmonic controller are studied in this paper. Firstly, a simple and accurate method for extracting current harmonics is proposed by means of multiple synchronous rotating frame transformation (MSRFT). Secondly, an improved deadbeat predictive control (IDPC) based current harmonic controller is designed after analyzing the advantages and disadvantages of traditional current harmonic controllers. Thirdly, IDPC-based current harmonic suppression strategy is proposed by combining the proposed current harmonic extraction method and the proposed current harmonic controller. The proposed strategy can still effectively achieve current harmonic suppression when the motor runs at low speed, medium speed and high speed and the controller parameters are mismatched with the motor parameters. Finally, the feasibility and effectiveness of the proposed strategy are verified by simulation and experiments.

In order to solve the problem that the three-phase current of the interior permanent magnet synchronous motor (IPMSM) contains the 11th and 13th current harmonics, a multiple synchronous rotating frame transformation (MSRFT)-based current harmonic suppression method is established. Firstly, the influencing factors of current harmonics in IPMSM vector control are analyzed, and the influence mechanism of the inverter’s dead-time effect and the permanent magnet flux linkage harmonics on the current harmonics is described. Secondly, a simple current harmonic extraction method is proposed by optimizing the traditional current harmonic extraction method based on MSRFTs. The proposed method achieves the accurate extraction of the current harmonic components. Thirdly, a harmonic voltage generation method is established and is combined with the proposed current harmonic extraction method to form a current harmonic suppression strategy. Finally, the feasibility and effectiveness of the proposed method are verified via MATLAB/Simulink simulations and experiments. The simulation and experimental results show that the proposed current harmonic extraction method can extract the current harmonic components accurately, and the proposed current harmonic suppression strategy can suppress the 11th and 13th current harmonics effectively.

The repetitive control technique is widely adopted in ac systems, because of its excellent steady-state tracking performance and low total harmonic distortion. The repetitive control method with one-sixth of the system fundamental period T0 as the delay time has been proposed to achieve fast transient response. In this study, an improved control scheme based on the T0/6 repetitive control is proposed for three-phase grid-connected inverters. The proposed scheme adopts T0/6 as the delay time in the positive-rotating and negative-rotating synchronous reference frames to suppress the 6n ± 1 harmonics. Meanwhile, the proportional-integral regulator and the plug-in repetitive controller are combined to reinforce the system performance. A new auxiliary function based on the linear interpolation is proposed to maintain the ideal repetitive control performance when one-sixth of the ratio of the sampling frequency to the grid fundamental frequency is non-integer. The effectiveness of the proposed scheme on improving the T0/6 repetitive control is confirmed by simulation and experimental results finally.