An AC Current Measurement Error Compensation Strategy of Three-Phase Grid-Tied PWM Converter Suitable for DC Bus System Application

Abstract

The three-phase grid-tied pulsewidth modulation (PWM) converter in the dc bus system is utilized to achieve energy conversion. Due to the influence of factors, such as time and temperature on sensors or conditioning circuits, the measured ac current values may have scaling and dc offset errors, leading to the imbalance and dc biases in the three-phase currents. It will affect the quality of electrical energy on the ac side, which is detrimental to the long-term stable operation of the system. Given that the voltage fluctuations of dc buses are influenced by various loads, traditional compensation strategies for current measurement errors cannot be directly applied. Therefore, this article proposes an ac current measurement error compensation strategy for the three-phase PWM converter in the dc bus system. The scaling error compensation coefficient is obtained by sequentially superimposing a dc value on the three-phase measured currents, and the dc offset error is obtained by sequentially blocking and clamping the three-phase bridge arms. The proposed strategy compensates for ac current measurement error without using dc voltage and current information, making it more suitable for the three-phase PWM converter in the dc bus system. Simulation and experimental results validate the effectiveness of the proposed compensation strategy.