An additional current sensor is needed in active damping technology based on capacitive current

which leads to extra hardware cost and increased system complexity and failure rate. An improved active damping technology using the grid voltage and current to estimate the capacitive current is then proposed. However

a delay caused by the digital controller exists between the estimated capacitive current and the true one. Thus the controller's damping effect as well as system stability is badly affected. To achieve satisfactory damping effect

phase compensation is made based on the estimated current. Simulations and experimental results have verified the effectiveness of the proposed active damping technology.