A current control method with impedance estimator for single-phase PWM rectifier

Current control is one of the simplest methods due to the current waveform is tracks the voltage waveform rapidly in AC side for single-phase PWM rectifier. If the voltage is not a normal sinusoidal signal, the current waveform will be distorted, so the power factor is not controlled and the current with harmonics will contaminate power supply. A current control method based on impedance estimation is proposed to solve the problem. In this new method, voltage with harmonics is decomposed into Fourier series. Their fundamental component is extracted in order to be tracked and controlled. What's more, an impedance estimator calculating resistor and reactor in controller is used to compensate the error voltage, which is generated by harmonics, the measurement of time delay and parameters variation. So the system not only realizes high power factor, sinusoidal current and stable DC link voltage, but also meet the application demand of the capability of power regeneration to the power supply. The results of experiment show that the proposed method is effective and practicable.