Research On Control Circuit Of Inverter Motor Based On DSP + FPGA

Multiphase inverter-driven speed regulation system is a new type of topological structure with respect to the traditional three-phase driven system for its phase redundancy, high reliability and smooth torque. Since high power drive can be accomplished with low voltage power electric devices in such structure, it is normally used in cases with limited space, especially in vessel propulsion system, which explains its continuous attention from researchers.Taking the speed regulation system of a fifteen-phase induction motor as the research subject, varies aspects in the implementation of multiphase frequency control and its theory are studied as follows:The magnetic motive force(MMF) of the fifteen-phase induction motor under non-sinusoidal supply is analyzed with the characteristics of such concentrated integral pitch winding proposed: the fifteen-phase induction motor allows the injection of the third order harmonic current for a flat wave of magnetic flux density, which improves the utilization of iron core and the output torque. The ideal operating conditions for the third harmonic current injection is also summarized. The mathematical model of fifteen-phase induction motor with concentrated integral pitch winding in natural system of coordinates is established, which is then transferred into mutual decoupling orthogonal planes of fundamental and third order harmonic MMFs in dq coordinate system as the theoretical foundation of Simulink modeling and vector control.The elementary principle of frequency control for a fifteen-phase induction motor under non-sinusoidal supply is introduced with its model established in Simulink. And the simulation results have a guiding role in selection of electric circuit element types as well as the determination of system parameters in software programming. The waveform of induced voltage in stator produced by the fundamental and third harmonic currents is simulated, which verifies the advantages of third harmonic current injection mentioned above.The structures of main circuit and control circuit for fifteen-phase frequency control speed regulation system is introduced. And the control circuit for such fifteen-phase machine is designed with the master controller composed of DSP and FPGA for the requirements of fifteen-phase system such as multi control signals, high control precision and fast data processing. The DSP mainly works on the control algorithm while the FPGA deals with the channel expansions of PWM as well as the voltage and current detection with the principle computer programmed by MATLAB GUI. DSP and FPGA are combined as a full digitization experiment platform with their data exchanged in real time. The waveform in experiment is recorded with multichannel recorder and oscilloscope, which is in a good agreement with the simulation results and verifies the validity and accuracy for the mathematical model of fifteen-phase induction motor under non-sinusoidal supply.