用于两相三线电网不对称负载的并网逆变器研究

Research on Grid Connected Inverter Applied to Two Phase Three Wire Grid and Unbalance Load

北美家用配网电压广泛采用两相三线型式,即由相位互差180°的双火线和零线组成。对于这种电压型式,并网运行的逆变器仍需考虑两相负载不对称问题。此外,对于非隔离型并网逆变器,采用直流中点与交流中性点互联的三电平拓扑可更好地抑制共模。针对北美两相三线电网电压,对非隔离型两桥臂三电平逆变器进行直流电压外环、逆变电流内环的控制,并叠加负载电流前馈,在稳定直流电压的同时实现对不对称负载电流的跟踪;同时,采用适当控制方法来抑制逆变器直流中点的偏移。最后,通过仿真与实验验证了该控制方法的有效性。

The type of North American domestic distribution voltage is two phase three wire,which consist of two live wires having phase difference180° and one neutral wire. Gird connected inverter applied to this voltage is also confronted with unbalance load. And then,three level structure with DC link midpoint connected to neutral point is adopted to restrain common mode voltage of non insolated grid connected inverter. The method of the outer DC voltageloop and the inner inverter current loop was adopted,which adding load current feed-forward,to achieve stabilization of DC link voltage and track of unbalance load current. Then,proper method was adopted to stable DC link midpoint voltage. The control method is validated by the simulation and experiment.