Research On Real-time Multi-rate Co-simulation Technology For Power Electronic System

In recent years, the power electronic device based on high frequency IGBT switching device has been widely used in the power field, such as distributed power grid, AD/DC power grid interconnection. In order to ensure the safety and reliability, it is necessary to simulate the dynamic characteristics of the power electronic deviced and the closed-loop control strategy in detail. The real-time simulation can completely realize the power electronic system about limit operation behavior and fault condition test under various working conditions, low cost and higher accuracy. However, the real-time simulation platform based on multi-PC and multi-DSP has been difficult to meet the requirements of high frequency power electronic device simulation. There have problems about the balance of simulation accuracy and the simulation efficiency,the code design of complex and the calculation burden. To solve these problems, the paper presents a co-simulation platform based on FPGA+DSP+PC, and the main work is as follows:1. The implementation of power electronics real-time multi-rate simulation platform.To solve the balance of simulation efficiency and the accuracy, PC+FPGA+DSP real-time co-simulation platform is built by using the multi-rate simulation principle in this paper.The simulation step size of FPGA can reach the nanosecond level, which meets the real-time requirements of high frequency switching device simulation.2. Research on the implementation of power electronic Model-Based Design. To solve write code, the paper use Model-Based Design kit to generate code automatically. The liner solver, the nonlinear solve, the data processing and the SPWM closed-loop control algorithm are implemented by using Model-Based Design method.3. Research on the modeling method of power electronic circuit model based on FPGA.To solve the calculation burden caused by high frequency switching operation, the paper use continuous discontinuous model separation to separate the nonlinear sub-model of high frequency switch from power electronic circuit, the larget liner sub-model having no need to be updated, reducing the computation. Liner sub-model uses the state-space approach to model and nonliner sub-model uses the swich-function approach to model.The three-phase two level inverter closed-loop control case is tested. Based on signal-rate off-line simulation, the real-time co-simulation results are compared with the single-rate off-line simulation and the multi- rate simulation from the simulation error, thesimulation speed and the FPGA resource consumption. The FPGA calculates inverter with500 ns simulation step and the DSP simulates closed-loop control part with 2us. The results show that the real-time co-simulation is 233 times faster than the multi-rate off-line simulation, and 991 times faster than the single rate off-line simulation, and the Euclidean norm is 1%.