基于电机励磁控制的斩波器吸收电路参数选取

某船用直流电机的励磁控制系统因吸收电路中的吸收电阻发热导致MOSFET管烧毁。基于励磁控制系统主电路的吸收环节,即一种采用调频板给予电路中MOSFET管PWM信号的带整流桥的降压电路拓扑结构,在确定电路中滤波电容与励磁绕组阻抗值大小的前提下,从吸收电阻耗能、降低MOSFET管开通峰值电流、交流端输出幅值电压3个方面考虑,对该吸收电路环节中电阻、电容参数的选择进行了仿真实验研究和最优选取。结果表明适当增大吸收电容和吸收电阻参数值可以有效地抑制开关管开通峰值电流,而且前者会增加吸收电阻的耗能功率,后者可以减小开关管开通时流过吸收电阻的冲击电流。从而得出结论,正确选择吸收电阻、电容参数值可以满足该励磁控制电路的稳定性和可靠性。

Selection of chopper absorption circuit parameter based on generator excitation control

In an excitation control system of ship DC generator,the MOSFET was burnt out due to the overheating of absorption resistor in absorption circuit.The absorption circuit of excitation control system is based on the Buck converter topology with the rectifier,which adopts a frequency modulation module to provide PWM signal for the MOSFET.With known filter capacitor and excitation winding impedance,the parameter selection is studied and simulated for the resistor and capacitor of absorption circuit in three aspects:the dissipative energy of resistor,the turn-on peak current of MOSFET and the output AC voltage amplitude.Results show that,the appropriate increase of resistor and capacitor parameters can restrain the turn-on peak current.The increase of resistor will increase its dissipative energy and the increase of capacitor will decrease the turn-on impact current through the resistor.The conclusion is that,the parameters of the absorption resistor and capacitor should be selected properly to satisfy the stability and reliability of excitation control circuit.