Research On The Control Manner Of Single-phase Feedback Electronic Load And Its Grid Filter

With the development of power electronics technology, a lot of power, such as UPS, EPS and others should be tested before production. It requires load test, but most of the traditional load are resistors, capacitors, inductors and other energy-type devices, which are regulated inconvenient and will cause great waste of energy. So the electronic load formed by the power electronic switching devices appeared, It is flexible, convenient, low energy consumption, and can simulate the load of any nature, to fully meet the needs of the experiment. Energy feed-line electronic load can meet the experimental needs and feedback power to the grid experiments efficiently at the same time.This thesis introduces the single-phase AC electronic load which can feedback power to the grid. At first, it introduced the development of domestic and foreign electronic load and its main topology and described the common control manner. Next, it introduced the PWM rectifier, which can run in four quadrants. What’s more, it gave the principle of grid filter. Based on these, this paper carried out the following research work.Firstly, the thesis proposed and determined the main circuit of two-stage energy-fed AC electronic loads. And it designed and calculated the load side of the analog components, and gave the driver circuit, the sampling circuit and conditioning circuits of the system. And then after comparing the indirect current control and direct current control, it comes up with control method that PWM rectifier uses a fixed switching frequency hysteresis control method in load simulation side, then analyzes the unipolar and bipolar modulation. At last arithmetic instructions have given current form when simulating various load, and conduct a simulation.After analyzing the previous stage, the thesis designed LCL grid filter and gave the calculation of each component parameters, and then analyze the different methods of damping LCL filter, and finally decided to adopt active damping law approach with active damping capacitor current feedback. Next, it designed the LCL type of grid-connected inverter control strategy, after pointing out the disadvantages traditional P, PI regulator bicyclic inadequate control strategy, raised the proportion of resonant(PR) control strategy. After a comprehensive analysis and consideration, we decided to adopt the current quasi-resonant control proportional way, and designed its parameters.Finally, the thesis conducted the MATLAB simulation and experiments on the load analog side and grid inverter side, and carried out to verify the feasibility and validity of the system design.