The variable switching frequency pulsewidth modulation (VSFPWM) is varying the carrier frequency of pulsewidth modulation (PWM) based on the prediction model to reduce the switching losses and lower the electromagnetic interference (EMI). However, it may cause some deterioration in digital dq current control of voltage source converters. This article takes the L-type grid-connected converter as the research object, and first presents the generation mechanism of the varying time delay caused by VSFPWM. In the case of proportional-integral current regulator implemented with VSFPWM, the varying time delay is accompanied by the frame rotation, which causes a varying phase lag in output voltages, degrading the system performance. Subsequently, an analytical method based on complex coefficient transfer functions is developed to provide an accurate explanation of the relation between the VSFPWM and the corresponding impacts. A compensation method is then proposed to eliminate the varying phase lag of output voltages when the VSFPWM is employed, improving the steady state and dynamic performance of dq current control. Finally, the simulation and experimental results are presented to verify the analysis and the effectiveness of the proposed compensation method.

中文翻译：

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VSFPWM对dq电流控制的影响及补偿方法

可变开关频率脉宽调制 (VSFPWM) 是根据预测模型改变脉宽调制 (PWM) 的载波频率，以减少开关损耗并降低电磁干扰 (EMI)。然而，它可能会导致电压源转换器的数字 dq 电流控制出现一些恶化。本文以L型并网变流器为研究对象，首先介绍了VSFPWM引起的变化时延的产生机制。在使用 VSFPWM 实现的比例积分电流调节器的情况下，变化的时间延迟伴随着帧旋转，这会导致输出电压的变化相位滞后，从而降低系统性能。随后，开发了一种基于复系数传递函数的分析方法，以准确解释 VSFPWM 与相应影响之间的关系。然后提出了一种补偿方法来消除采用 VSFPWM 时输出电压的变化相位滞后，提高 dq 电流控制的稳态和动态性能。最后，通过仿真和实验结果验证了所提出的补偿方法的分析和有效性。