Abstract
High-frequency common-mode voltage generated by inverters causes severe negative effects, particularly in silicon carbide (SiC) Metal-Oxide-Semiconductor Field-Effect Transistors (MOSFETs)-driven motors. Additionally, common suppression strategies would increase hardware expenses or sacrifice the switching speed of SiC devices. This article proposes an improved no-zero vector modulation strategy to suppress high-frequency common-mode voltage without increasing the cost of hardware. In this method, only nonzero vectors are utilized to reduce common-mode voltage. Firstly, the influence of different switching states on the characteristics of SiC MOSFETs has been studied by double-pulse tests, which explains why zero vectors will cause more serious voltage oscillations. Secondly, common-mode voltage suppression failure caused by the high-frequency dead zone effect has been analyzed in detail. Based on traditional Active Zero State Pulse Width Modulation (AZSPWM), complementary device conduction logic and dead-zone compensation methods are proposed. In switching moments, different turn-on logic is selected to ensure that only one switch acts, and different dead zone compensation methods are selected to deal with the common-mode suppression failure, which effectively avoids high-frequency common-mode voltage spikes. Finally, simulation and experimental results verify that the improved modulation algorithm can effectively suppress high-frequency common-mode voltage.
Highlights
Silicon carbide devices have unparalleled advantages in high-frequency and highpower-density applications due to their fast switching speed, high voltage level withstood, and high working temperature, which are designed to improve the efficiency and power density of motor drive systems [1,2]
Reference [9] verified that common-mode voltage can be effectively suppressed under active zero state PWM (AZSPWM) and Near State Pulse Width Modulation (NSPWM), but the influence of dead zone effect on the common-mode voltage is neglected
Different turn-on logic is selected to ensure that only one switch acts to avoid the common-mode voltage spike, and different dead zone compensation methods are selected to deal with the common-mode suppression failure caused by different switches
Summary
Silicon carbide devices have unparalleled advantages in high-frequency and highpower-density applications due to their fast switching speed, high voltage level withstood, and high working temperature, which are designed to improve the efficiency and power density of motor drive systems [1,2]. Studies have shown that high-frequency common-mode voltage generated by PWM inverters is the main reason for the problems related to EMI in the motor drive system [3]. To solve the problems such as EMI in SiC motor drive system, it is necessary to effectively suppress high-frequency common-mode voltage. Reference [9] verified that common-mode voltage can be effectively suppressed under AZSPWM and Near State Pulse Width Modulation (NSPWM), but the influence of dead zone effect on the common-mode voltage is neglected. In reference [10], the influence of dead zone on the common-mode voltage of AZSPWM is analyzed, but only dead zone compensation is carried out for the failure of one of the two effective switching vectors.
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