Determination methodology for stable control domain of electric powertrain based on permanent magnet synchronous motor

Oscillation of torque and speed occurs in the electric powertrain based on permanent magnet synchronous motor under field-oriented control when we set an unreasonable proportional control parameter of proportional-integral regulator. Thus, it influences the stability and reliability of electric powertrain. The objectives of this article are to study nonlinear dynamics of electric powertrain under various complex operating conditions and settle a minimum stable range of proportional control parameter of proportional-integral regulator. To achieve these goals, nonlinear dynamic model of electric powertrain was established. Then, we solved equilibrium points and analyzed the stability of equilibrium points. Finally, we set different control parameters of proportional-integral regulator and various complex working conditions of electric powertrain to simulate nonlinear dynamics of electric powertrain. The simulation results show the electric powertrain operates stably when the control parameter is set in the area where there is only one stable equilibrium point. Chaos do exist in the electric powertrain with field-oriented control under different working conditions. Our analysis reveals the dynamics of electric powertrain are dependent on proportional control parameters of proportional-integral regulator and electric powertrain performs unstably most likely under the operating condition with no-load and zero reference rotational speed.