A Semi-Controlled Soft Charge Rectifier For Medium/High Power Ac Drives: Design And Implementation

One of the important issues in designing of AC drives is soft charging of DC-link capacitors. With the increase of electric drive power, the DC-link soft charge challenge becomes even more serious. In this case, other common methods of controlling the inrush current such as resistive pre-charge circuits are not suitable for charging DC-link capacitors. This paper presents the design and experimental evaluation of a semi-controlled soft charging rectifier for the DC-link of AC drives. The STM32F103C8 ARM microcontroller is employed for digital implementation of the control system and generation of thyristors' firing pulses. The employed method is robust against noises and correctly diagnoses the sequence of phase voltages. The simulation and experimental results confirm the validity and effectiveness of the employed method. The advantages of this circuit are its lifespan, lower size, and lower cost compared to alternative topologies.