On Low Voltage High Current Parallel High Frequency DC Switching Power Supply Module

Nowadays, in the low voltage high current field, the demand for the high frequency switching power supply is becoming bigger and bigger. Compared to the single large module, paralleled power supply modules have significant advantages in supplying high output current. The current-sharing control is one of the key issues for design a parallel power supply system. This paper analyzes the present development status and the hot research issues of the high frequency switching power supply, based on its development history. The methods of current-sharing are discussed in detail, based on the analysis of the working principle of high frequency switching power supply. Then, the paper focuses on the design of current-sharing which use multiple identical constant-current power supply to build the paralleled power system. The design of2+1redundant hot backup is presented.The paper introduced a design of the low voltage big current high frequency DC switching power supply module which can be used to build parallel power system. The module consists of the AC input circuit, three phase uncontrolled rectification, full-bridge hard switching inverter, whole wave rectifier, output filter and control circuit. IGBT is used as the switching element. The PWM wave generate chip SG3525and current feedback control circuit is used to build current stabilization circuit. Special integrated driver HL402is used as the core driver circuit of IGBT. The hall current sensor is used to measure the output current accurately, and generate the feed back current signal. The feed back current signal and the given current signal are processed by PI control circuit. The control circuit adjusts the output current by control the PWM duty ratio according to the output signal of PI control circuit. The high frequency switching DC power supply module has many trouble protection circuits, such as over current, over voltage, under voltage and over temperature trouble protection circuit. With all these protection circuit, it greatly improved its safety.At last, the paper adopt S7-200type PLC and other circuit to design the main controller, use its concise powerful software instructions to program and realized the high power2+1redundancy parallel power supply system. This design has the characteristics of modular and high-frequency. It can expand the capacity easily, and realize current-sharing naturally.