Error Self-Calibration of Phase Current Reconstruction Based on Random Pulsewidth Modulation

Abstract

Three-phase current is the cornerstone parameter in vector control. Restricted by minimum sampling time of the traditional space vector pulsewidth modulation (PWM), the problem of immeasurable areas (IAs) exists in one dc bus current sensor (ODBCS) three-phase current reconstruction. In addition, affected by actual conditions such as temperature drift, aging, and noise, the problem of offset error (OE) in the three-phase current sampling path is the essential factor that restricts the sampling accuracy. This article is the first to investigate the influence of IAs and OE of ODBCS on the reconstructed current. An error self-calibration (ESC) random PWM reconstruction strategy is proposed, which is self-detection and self-calibration of current OE accomplished by dual sampling of the complementary nonzero vector dynamic current. The proposed ESC of phase current reconstruction based on random PWM does not require the insertion of redundant voltage vectors and major computation and is not limited to a particular PWM technology. The experimental results verify the accuracy and practicability of the proposed method.