DC Bus Voltage Feedback Based Resonance Suppression for Electrolytic Capacitor-Less Drive Systems

In order to mitigate grid-side current harmonics, a DC bus voltage feedback based virtual damping method for motor control in electrolytic capacitorless systems is proposed in this paper. Firstly, according to transfer function analysis, the virtual damping method with different configurations is thoroughly investigated, revealing the distortions in bus voltage and motor phase currents that are triggered by LC resonance between filter inductance and film capacitor. To solve the issue, a new bus voltage feedback method is developed. In this way, a damping current is generated, and the corresponding damping voltage is injected into the driver through the principle of minimum perturbation, where the equivalent damping can be achieved. The proposed method eliminates the need for a DC bus current sensor and the distortion of the DC bus voltage can be substantially reduced. Simulations are performed to verify the effectiveness of the proposed method.