EMI-Regulated SiC-Based Motor Drives with Markov Chain Pseudo-Random Frequency Space Vector Pulse Width Modulation Strategy

Compared with traditional silicon-based (Si) power devices, wide-bandgap (WBG) power devices have broader application prospects in AC motor drive due to their high-temperature reliability, low conduction, and switching losses. However, a fast switching process and high switching frequency will cause more serious conducted electromagnetic interference (EMI) emission. To solve the problem, this paper proposed a pseudo-random frequency space vector pulse width modulation (PRF-SVPWM) strategy based on a carrier with a pseudo-random frequency. There are two sawtooth waves with the same frequency but opposite phases as alternatives. The proposed method randomly selects only one sawtooth wave during a complete control period. After random combination, the generated carrier is no longer a regular sawtooth wave. This new carrier contains 4 different modes including 2 sawtooth (positive and negative) and 2 triangular waves (positive and negative). A 2-state Markov chain is introduced to produce a PRF control signal which is regarded as the law of choice. In this way, the equivalent switching frequency keeps constant but the real-time switching frequency will randomly vary within the determined range. EMI emission level can be significantly reduced. The effectiveness of the proposed PRF-SVPWM is verified by several sets of experiment results.