Two-Level Grid-Connected Discharge Inverter System of Power Battery Based on LLC
In order to overcome the large amounts of energy waste in the process of power battery discharge, the two-level grid-connected discharge inverter system of power battery based on LLC is designed. It is composed of LLC resonant full-bridge DC/DC and inverter. The DC-bus voltage is changed and the discharge current is stabilized by adjusting the frequency of the LLC resonant full-bridge DC/DC. The dual-loop control is applied in the inverter system. The stabilization of DC-bus voltage is achieved in the external voltage loop, while the grid-connected is implemented by controlling the grid-connected current in the inner current loop. A prototype is manufactured. The experiment results indicate that it has the characteristics of low harmonic current, high power factor and constant current discharge, and then proves that the inverter system is effective.