Research On Low Frequency Torque Compensation Control Algorithm For Inverter Air Conditioner Compressor Drive System

Abstract:With the development of rare earth materials, power electronic technology and modern AC servo motor drive control technology, the permanent magnet synchronous motor (PMSM) is more widely applied In various fields. Permanent magnet synchronous motor is the core of the household variable frequency air condition compressor drive energy saving technology and has become the important research subject at present. But the problem that load torque ripple on low frequency has not been solved perfectly on the drive system of variable frequency air condition compressor. The paper will have a research on the problem that the low frequency load torque always has the sharp fluctuations when variable frequency air condition compressor runs in low frequency. The main research contents of this paper are as follows:(1) At the time of variable frequency air condition compressor works in low frequency, the load torque always has impulse type sharp rolling, in order to solve this problem, this paper put forward a method to compensate the low frequency torque of permanent magnet synchronous motor based on control parameterization. The method divided a machine period to several subintervals and the nonlinear load torque was equivalent to a literal load in period of each subinterval. Then, controlled quantity of each subinterval can be got by optimal computation. Control parameterization method can very good to adapt to the mechanical characteristics of motor at low frequency, but also can largely improve the control precision of low frequency band.(2) In illusion to the problem of the low frequency pulsation of inverter compressor, we put forward a method to compensate the low frequency torque of permanent magnet synchronous motor based on model predictive control(MPC). First, this paper simplified the nonlinear constrained relationship of the mathematical equation in two phase rotating coordinate system of permanent magnet synchronous motor, for load disturbance problems in Model, we add to cross-axis voltage compensation control to obtain linearized motor model. Second, Motor load is estimated using the real-time detection of motor speed and current values, and future dynamic of systems is predicted by linear model. By optimizing the control action makes the model predicted control output close to the solved ideal control curves by control parameters. Finally, the first step of optimal control solved by each sampling time is applied to actual systems. The simulation and experimental results show the correctness and feasibility of the proposed control strategy. Figures (37), tables (2), references (62).