Power Control for Household Energy Storage Inverter With Smooth Mode Transition

With the conventional control, there are problems of battery current oscillation and loads voltage distortion because of the control loops switching. This article proposes a charge-discharge power control to avoid battery current oscillation and fast response of dc bus voltage regulation to solve the above problems. The idea is to avoid control loops switching during the mode transition with unified power control loop. A 5-kW household energy storage inverter was built, the charge to discharge transition time is 1.17 s, and the discharge to charge transition time is 1.18 s, which are reduced by 77.8% and 82.5% over the conventional control. The transition process is smooth and seamless. When a sudden failure of the grid happens, the bus voltage drop is 59.6 V and the recovery time is 0.2 s, which are reduced by 48.2% and 83.3%. The off-grid voltage/current distortion is reduced significantly.