An improved control method for PWM current source rectifier with active damping function

The pulse width modulation (PWM) current source rectifier requires an LC filter to filter out the line current harmonics and to assist the commutation of switching devices, however, the use of the filter may affect the input power factor and cause LC resonances as well. In order to overcome the two drawbacks the LC filter brings, an improved control method for PWM current source rectifier with active damping function is proposed in this paper. The proposed power factor control method is based on the source voltage oriented d-q rotating frame, which is parameters insensitive and can make the rectifier get the maximum achievable power factor. Meanwhile, in order to suppress the LC resonance and to reduce the line current total harmonic distortion (THD) without the physical damping resistor, the active damping technique is adopted, which is realized together with the power factor control, directly through detecting the capacitor voltage. All these analyses and the effectiveness of the control method are firstly demonstrated by simulation results, and are verified further in a 5kVA laboratory prototype.