Power conversion circuit, inverter, and control method

A hybrid modulation control method, the method applied to a power conversion circuit, and the power conversion circuit comprises a switching network, a control circuit, a filter circuit, a direct current side circuit, and an alternating current side circuit;

• the switching network is connected to the direct current side circuit, the switching network is connected to the control circuit, the switching network is connected to the filter circuit, the filter circuit is connected to the alternating current side circuit, the switching network comprises a first converter bridge arm and a second converter bridge arm, the first converter bridge arm comprises a first switching device and a second switching device, and the second converter bridge arm comprises a third switching device and a fourth switching device;
• and
• the method comprises:
• controlling, by the control circuit, the first switching device and the second switching device of the first converter bridge arm through a first sine modulated wave and a first carrier;
• and
• controlling, by the control circuit, the third switching device and the fourth switching device of the second converter bridge arm through a second sine modulated wave and a second carrier, wherein
• bipolar modulation is performed on the first carrier and the second carrier in a first preset angle range, unipolar modulation is performed in a second preset angle range, the first preset angle range is set based on a direct current bias point of the first sine modulated wave or the second sine modulated wave, the second preset angle range is an angle other than the first preset angle range in a sine wave period of the first sine modulated wave or the second sine modulated wave, and a switching frequency of the bipolar modulation is higher than a switching frequency of the unipolar modulation.

A photovoltaic power generation system, comprising:

• a photovoltaic panel, an inverter, and an alternating current network, wherein
• the photovoltaic panel is connected to the inverter, and the inverter is connected to the alternating current network;
• the photovoltaic panel is configured to convert light energy into a direct current;
• the inverter comprises the power conversion circuit, and is configured to convert the direct current into an alternating current;
• and
• the alternating current network is configured to transmit the alternating current;
• wherein the power conversion circuit comprises:
• a switching network, a control circuit, a filter circuit, a direct current side circuit, and an alternating current side circuit, wherein
• the switching network is connected to the direct current side circuit, the switching network is connected to the control circuit, the switching network is connected to the filter circuit, and the filter circuit is connected to the alternating current side circuit;
• the control circuit is configured to control the switching network;
• the filter circuit comprises a first power inductor, a common mode choke, a first differential mode filter capacitor, a first common mode filter capacitor, and a second common mode filter capacitor;
• the first power inductor comprises a first winding and a second winding, and the common mode choke comprises a third winding and a fourth winding;
• both a first end of the first winding and a first end of the second winding are separately connected to the switching network, a second end of the first winding is connected to a first end of the third winding, and a second end of the second winding is connected to a first end of the fourth winding;
• and
• two ends of the first differential mode filter capacitor are respectively connected to the second end of the first winding and the second end of the second winding.