Method for estimating the speed and rotor position angle of a synchronous motor

Abstract

The application belongs to the field of electrical engineering and can be used in inverter control systems for permanent magnet synchronous motors, including implementation in central processor blocks to evaluate the speed and rotor position angle of a synchronous motor. The essence of the application is that, according to the method in the evaluation module of the central processor (CP) of the MC microcontroller of the FC inverter, the angular speed of the rotor is determined by changing the rotor position angle depending on the current value of the induced stator current during rotor rotation. Using a set of sensors at the inverter output, which are installed after the inverter's sinusoidal filter, the current (Ia, Ib) is determined at the inverter output. The voltage (Ua, Ub) at the inverter output is obtained from the inverter's PWM pulse width modulation (PWM) module.In a separate observer module block, they determine the motor's rotor electromotive force (EMF) (Ea, Eb), based on the stator resistance (RS) and stator inductance (Ls) values ​​previously calculated by the CP blocks. Then, in the observer module's rotor angle determination block, they determine the current calculated value of the motor's rotor angle ¨e based on the inverse EMF value. Next, in the filter block, they filter the current calculated value of the rotor angle ¨e using the phase-dependent frequency autotuning method (PLL filter). They determine the cut-off frequency (f) of the PLL filter based on the calculation of ensuring the immunity of the inverter control system to changes in the stator resistance (RS) and stator inductance (Ls) of the motor within 30%.