The Research And Design Of Low Voltage And High Current System

With the rapid development of China’s electric power industry,electric power has already become one of the most important energies in national life.In various electrical devices and electronic equipment,high-current equipment is widely used.The concept of "high-current" is not an absolute value,and its extension and connotation are different in different application fields.In the field of transportation,in addition to the motor drive of electric cars,the core components of the starting system of traditional cars are low-voltage high-current systems.The DC voltage is usually supplied by a battery,and the voltage is generally a low voltage of 12 to 48 V,and the current is in the range of several hundred am to several thousand amperes.The low-voltage high-current system studied in this paper belongs to this category.The low-voltage and high-current system described in this paper designs the controller of a 24V,11KW series-excited DC starter for a heavy-duty locomotive.From the perspective of parallel application of power devices,the original controller is improved to effectively control the armature current when the motor starts.In this paper,the topology of the main circuit and the selection of power semiconductor devices are discussed,and the half-bridge circuit based on 14 power MOSFET parallel circuits is selected as the main topology.The problem of parallel current sharing of multiple MOSFETs.gate protection of MOSFET.overvoltage protection,overcurrent protection and other issues have been fully investigated and discussed.Then I designed the hardware circuit schematic diagram and PCB circuit board of the controller in Altium Designer software,and designed the driver circuit based on LM25101 driver chip.In the control part,the 32-bit ARM core control chip STM32F103 is selected,and the corresponding software program is developed to control the current by means of PWM modulation.Finally,the controller with dc motor is tested in the laboratory and compared with the original controller.Experimental results show that the low-voltage high-current system designed in this paper can effectively control the starting current of dc motor,reduce the impact on the motor,and have a more stable starting effect.