Predictive Current Control Of Permanent Magnet Synchronous Motor In High-speed And Low-control-frequency Condition

Model predictive current(MPC)control is a high-performance control strategy widely used in high-efficiency permanent magnet synchronous motor(PMSM)drive system because of its enhanced transient response of the system.However,during high-speed operation that the ratio of control frequency to motor operating frequency is low,the discrete models used in traditional MPC have large errors,causing decrease capability in current control.In order to solve the problem mentioned,the relevant research works are carried out in this paper.In this paper,the discrete models of PMSM obtained by forward Euler approximation method are analyzed firstly,and the errors in free components and forced components caused by forward Euler approximation are assigned.Combined with the rotor movement during one control period,the influence of motor speed and control frequency on the above error is also analyzed,and the reasons why the discrete models obtained by forward Euler approximation have large error in high speed and low ratio of control frequency to motor working frequency are explained.Then,discrete models suitable to high speed and relatively low control frequency condition are established.They are derived by solving the differential equations neglecting resistance term in d-q coordinate directly with considering the rotor movement during one control period.The established models have less model inaccuracy during high-speed operation.Moreover,aiming at the model inaccuracy caused by neglecting resistor term and nonlinearity of the inverter,and parameter mismatch caused by deviation of motor parameters used in the controller from theirs real ones,a current compensation scheme is proposed to eliminate the static current tracing errors caused by factors above.Finally,combining the derived discrete models and current compensation scheme,an MPC strategy is proposed.The proposed strategy have realize current control in high-speed and relatively low-control-frequency condition.The feasibility of proposed the MPC scheme is analyzed on a 20 k W two-level voltage-source inverter interior permanent magnet synchronous motor platform.The experimental results show that the PCC scheme proposed in this paper is suitable for the case of high-speed,relatively low control frequency and parameter mismatch operation,and it can realize the current tracing without static error.