Design Of A DC Motor Soft Starter

Battery power DC motor in power system is widely used in the field of electric power,chemical and environmental protection,etc.When DC motor starts directly,the starting current is great,and will cause damage to the motor and the battery,moreover,it will shorten service life of the motor and battery.Therefore,it's needed to install soft-start device to limit starting current in a reasonable range.This paper designed a soft starter for DC motor which adopted IGBT full control device and STM32 microprocessor to achieve stepless and non-contact control,so the function of soft start,soft stop and protection of the DC motor can be realized.The soft starter is based on modular design,which mainly includes battery,auxiliary power supply,buffer circuit,IGBT module,driving circuit,STM32-based control circuit,detection circuit and touch screen circuit.The soft starter with self-test function is easily maintained,and can ensure the motor in normal state.Startup parameters such as motor starting limited current,PWM starting duty cycle can be set through the touch screen interface.The control circuit can adjust PWM duty cycle according to armature current to complete soft start.In addition,the touch-screen interface shows the power waveform when the motor starts,which provides convenience to install soft starter and debug it.Experimental prototype is made to test the DC motor starting with rated voltage 220 V,and rated power 22 kW.The experiment results show that this soft starter can achieve soft start and brake control,and the starting current is limited in rated current,which verified the feasibility and correctness of the design.