Design Of DC Energy-feedback Electronic Load With Harmonic Compensation

Power supply equipment usually needs to undergo aging treatment and dynamic and static performance testing before leaving the factory.In the current aging and performance testing process,grid-connected energy-feeding electronic load is usually used as the load of the power supply equipment to recycle energy.However,the existing grid-connected energy-feeding electronic load does not consider the grid harmonic interference caused by the power supply input rectifier,and the energy-feeding electronic load designed for low-voltage DC power supplies usually adopts a three-stage circuit structure,which makes the energy feedback efficiency hard to further improve.In view of the above problems of the energy-feedable DC electronic load,this paper proposes an energy-feedable DC electronic load with harmonic compensation suitable for lowvoltage DC power supply testing.The designed DC electronic load adopts a two-stage circuit structure,including a load simulation stage circuit that uses Boost converter as a topology structure and an energy feedback stage inverter circuit that uses Three-phase combined inverter which consists of three Bi-directional Voltage Mode Inverters with High Frequency Link.The load simulation stage controls the output current of the power supply under test according to the given signal to achieve the purpose of simulating a true passive load.The energy feedback stage inverts the energy obtained by the load simulation stage to the input end of the DC power supply,and compensates the grid current harmonics.In this paper,the 24 V / 500 A DC power supply is used as the test object,the power circuit,voltage and current sampling circuit and drive circuit of the DC electronic load are designed.The current fundamental wave separation algorithm is designed using the ip-iq method based on the instantaneous reactive power theory.Based on this,an energy feedback and harmonic compensation algorithm suitable for this subject is proposed.This paper introduces the working principle of Boost converter and Bi-directional Voltage Mode Inverters with High Frequency Link,and puts forward the Three-phase combined inverter which consists of three Bidirectional Voltage Mode Inverters with High Frequency Link,and then analyzes The singlephase equivalent principle of Three-phase combined inverter.On the basis of completing the power circuit design,this paper uses the state space averaging method to obtain the complex frequency domain model of the load simulation stage input current control and the energy feedback stage output current control;then the PI Controller of the load simulation stage and the Parallel PI plus Repetitive Controller of Energy Feedback Stage are designed according to the relevant knowledge of the control theory.In this paper,TMS320F28335 is used as the main controller,and the program running process is given.At the same time,FPGA is used to expand the PWM signal of DSP to meet the requirements of driving more energy feedback stage switching devices.Finally,this paper builds a simulation model of the system on the MATLAB / Simulink platform according to the above design content.Through the analysis of the simulation waveforms,the feasibility of the project's design scheme is verified.This paper also builds a load simulation stage hardware platform for experiments.The experimental results further prove the speed and effectiveness of the load simulation stage for tracking a given current.