Research On Parallel Control Of Combined Three Phase Inverter Based On CAN Bus

As an important part of AC power supply,three phase inverter is widely used in the field of electric vehicles,shipbuilding and banks.The parallel control technology of three phase inveter can make power supply redundant and high-capacity,which is one of inverter's development trends.In this paper,with two 75 kVA combined three phase inveters as a research object,research on the waveform control technology and the parallel control technology was carried out.First,according to the waveform control of the combined three phase inverter,the mathematical models in different coordinate systems of three phase inverter were established.Those models were continuous-time state space model,the transfer function model and the block diagram model.The 1.5 beat control delay introduced by asymmetric sampling SPWM was emphatically analyzed.This paper mainly study the composite control strategy of PI control plus repetitive control.The principle of PI controller and repetitive controller was analyzed,and the corresponding controller design method was given.And then,the principle of repetitive controller for harmonic suppression was analyzed and verified by simulation.Second,according to the parallel control of the combined three phase inverter,the mathematical models of circulating current and output power of parallel system were established.Parallel control strategy based on the average active and reactive power control is used.The loop of average power regulates the phase and mangnitude of output voltage according to the output active and reactive power difference.CAN bus is responsible for the synchronization of each inverter's voltage reference and the transmission of the output active and reactive power signal.Finally,the experimental verification is realized in two 75 kVA combined three phase inverters.The experimental result verifies the feasibility of voltage waveform control and parallel control scheme of high power three phase inverter.