Converter and method for driving converter

A method for driving a converter, wherein the converter comprises a switch circuit comprising a first switch, a second switch, and a third switch;

• and a filter, wherein a first end of the first switch is connected to a first end of a direct current voltage source, a second end of the first switch is connected to a second end of the direct current voltage source, and a third end of the first switch is connected to a third end of the direct current voltage source;
• the first switch comprises four switch devices that are sequentially connected in series:
• a first switch device, a second switch device, a third switch device, and a fourth switch device, wherein a first end of the first switch device is the first end of the first switch, a second end of the fourth switch device is the second end of the first switch, and a connection point between the second switch device and the third switch device is the third end of the first switch;
• and the first end, the second end, and the third end of the direct current voltage source are respectively configured to provide a positive level, a negative level, and a zero level;
• a first end of the second switch is connected to a first connection point, and the first connection point is a connection point between the first switch device and the second switch device;
• a second end of the second switch is connected to a second connection point, and the second connection point is a connection point between the third switch device and the fourth switch device;
• a third end of the second switch is connected to an input end of the filter;
• and the second switch comprises a fifth switch device and a sixth switch device that are connected in series, wherein a first end of the fifth switch device is the first end of the second switch, a second end of the sixth switch device is the second end of the second switch, and a connection point between the fifth switch device and the sixth switch device is the third end of the second switch;
• a first end of the third switch is connected to the first end of the direct current voltage source, a second end of the third switch is connected to the second end of the direct current voltage source, and a third end of the third switch is connected to the input end of the filter;
• and the third switch comprises a seventh switch device and an eighth switch device that are connected in series, wherein a first end of the seventh switch device is the first end of the third switch, a second end of the eighth switch device is the second end of the third switch, and a connection point between the seventh switch device and the eighth switch device is the third end of the third switch;
• and a switching frequency of each switch device in the first switch is a power frequency, and a switching frequency of each switch device in the second switch is a high frequency;
• a switching frequency of the seventh switch device is a preset frequency in a switch-on phase of the first switch device, and the seventh switch device is in a switch-off state in a switch-off phase of the first switch device;
• and a switching frequency of the eighth switch device is the preset frequency in a switch-on phase of the second switch device, and the eighth switch device is in a switch-off state in a switch-off phase of the second switch device;
• the method comprising:
• in a first drive phase, switching on the first switch device and the third switch device in the first switch;
• switching off the second switch device and the fourth switch device in the first switch;
• switching on and switching off each of the fifth switch device and the sixth switch device in the second switch at a high frequency, and alternately switching on the fifth switch device and the sixth switch device;
• switching on and switching off the seventh switch device in the third switch at a preset frequency;
• and switching off the eighth switch device in the third switch, wherein in at least one switch-on period of the fifth switch device, the seventh switch device and the fifth switch device are switched on at the same time, or the seventh switch device is switched on after a preset time period, and the seventh switch device is switched off before the fifth switch device is switched off;
• when the fifth switch device is switched on, the first end of the direct current voltage source is connected to the input end of the filter;
• and when the sixth switch device is switched on, the third end of the direct current voltage source is connected to the input end of the filter;
• and
• in a second drive phase, switching off the first switch device and the third switch device in the first switch;
• switching on the second switch device and the fourth switch device in the first switch;
• switching on and switching off the fifth switch device and the sixth switch device in the second switch at the high frequency, and alternately switching on the fifth switch device and the sixth switch device;
• switching on and switching off the eighth switch device in the third switch at the preset frequency;
• and switching off the seventh switch device in the third switch, wherein in at least one switch-on period of the sixth switch device, the eighth switch device and the sixth switch device are switched on at the same time, or the eighth switch device is switched on after a preset time period, and the eighth switch device is switched off before the sixth switch device is switched off;
• when the sixth switch device is switched on, the second end of the direct current voltage source is connected to the input end of the filter;
• and when the fifth switch device is switched on, the third end of the direct current voltage source is connected to the input end of the filter.