Resonance Suppression of Photovoltaic DC Boost Collection System Based on Active and Passive Damping Cooperative Control

In a photovoltaic DC collection system, the impedance matching between the LC circuit and switching circuit in the DC/DC converter is easy to generate resonance, which leads to the system stability deterioration or even collapse. In order to solve the resonant problem of the converter due to impedance matching, the active and passive damping cooperative control is proposed to eliminate the resonance. Firstly, the small-signal impedance model of the converter under different operating conditions is established. Secondly, the impedance ratio criterion is used to analyze the stability differences of the system, and the influence of different virtual resistance values on the system stability is discussed. Finally, by using the ratio of the equivalent impedance amplitude between the angular frequency point at which the resonance peak is generated and its neighboring normal angular frequency point limited between [0.95, 1.15], the closed-loop output impedance amplitude of the converter under MPPT control with the value of the damping resistor is obtained to be improved by about 1.5 times. The results show that compared with only active or passive damping control, the proposed cooperative control strategy increases the amplitude at resonance generation from -15dB to 40.5dB, which is about 4 times, and the system has large amplitude margin and phase margin, which effectively improve the stability of the system.