Research on the current control method of N-paralleled converter system for the high-power inductor tester

Abstract

This paper develops the N-paralleled converters with LCL filter system model and expands the virtual resistor control method for harmonic current control. Power electronic converter can be controlled as a current source. For some application the current source can be used to test the inductor characteristic, such as temperature rise, noise or vibration. While in some cases, several converters are connected in parallel to increase the output current amplitude. The N-paralleled converters with LCL output filter system presents complex resonances feature. And the output current of the system becomes out of control. This paper develops the closed-loop model of N-paralleled converters with the LCL filter system and reveals the output current amplification by analyzing the resonance feature of the system at first. Then the virtual resistor based current control method is expanded in the harmonic current control. For the application of N-paralleled converters with an LCL filter system to test the inductor characteristic, the amplitude of output harmonic current need be considered carefully. With the optimal virtual resistor value the output harmonic current can also be controlled well. Simulation and experimental results prove the validation of the system model and optimization for damping resistor value.