The Analysis And Applation Of Cascade Technology For High Voltage DC Power Supply

With the development of our industry,the application of high voltage DC power supply is becoming more and more extensive.The traditional high voltage power supply is limited in industrial applications because of its large size and low efficiency.And with the evolution of power electronic devices,small size,high frequency and high efficiency of switching power supply is also developing rapidly.However,due to the limited process level of power electronic devices,the voltage level of the power electronic devices can't meet the requirements of some special occasions.That requires the use of multiple power modules(series or parallel).The cascade technology of power supply is to form a new power supply system with the input and output of the small power supply module.This system is called the cascade power supply system.The small power module is called the sub module of the cascade power supply system.By means of different cascaded mode,the cascaded power supply system with different requirements can be obtained.In this paper,the cascade technology of high voltage DC power supply is to put the voltage level of the power supply module in parallel,the output in series,to obtain a large voltage.As the input voltage and output current of each module is naturally equal in this connection mode,so the key technology of the Cascaded High Voltage DC power supply system is to ensure that the input current and output voltage of each module are equal.For better control of the voltage and current sharing of each module,the circuit characteristics of a single module should be mastered firstly.Here we choose the LCC resonant DC-DC model as the sub module.By analyzing the working principle of a single module,the voltage closed control loop is obtained.To lay a foundation of voltage and current sharing.Because the parameters of each module of the Cascaded High Voltage DC power supply are not fully matched,the power supply system can't operate stably by using uniform frequency control.So it is necessary to control each module separately.No matter which control strategy is adopted by the Cascaded High Voltage DC power supply system,there will always be an output voltage closed loop to control the output voltage of the system.In this paper,we focus on the selection of the module,the factors affecting the voltage and current sharing and the method of controlling the Cascade High Voltage DC power supply system.At last,the effect of different control strategies and the output voltage in the closed-loop control are verified by simulation.