Inverter and power converter having inverter mounted therein
View Patent ↗Disclosed is an inverter having improved power conversion efficiency. The inverter ( 200 ) converts direct current power supplied from a plurality of direct current power supplies (V 1 , V 2 ) having different voltages into alternating current power. The inverter ( 200 ) is provided with a control unit ( 20 ). The control unit ( 20 ) generates modified sine waves using a power supply voltage (E 1 ) of the power supplied from the first direct current power supply (V 1 ), a power supply voltage (E 2 ) of the power supplied from the second direct current power supply (V 2 ), and a potential difference (E 1 −E 2 ) between the two power supply voltages. The control unit ( 20 ) generates the modified sine waves by controlling H bridge circuits provided for the direct current power supplies (V 1 , V 2 ), respectively.
1. An inverter that generates a pseudo sine wave as an alternating-current voltage output and applies the pseudo sine wave to a load, the inverter comprising:
a switching element S 11 and a switching element S 12 ;
a switching element S 21 and a switching element S 22 ;
a first common switching element S 3 and a second common switching element S 4 ; and
a controller, wherein
the switching element S 11 is inserted into a path connecting a high-potential-side terminal of a first direct-current power supply V 1 and a high-potential-side terminal of the load,
the switching element S 12 is inserted into a path connecting the high-potential-side of the first direct-current power supply V 1 and a low-potential-side terminal of the load,
the switching element S 21 and the switching element S 22 are provided in parallel between a high-potential-side of a second direct-current power supply V 2 and the load,
the first common switching element S 3 and the second common switching element S 4 are provided in parallel between a low-potential side of the second direct-current power supply V 2 and the load,
the controller generates a voltage E 1 from the first direct-current power supply V 1 by controlling the switching element S 11 , the switching element S 12 , the first common switching element S 3 , and the second common switching element S 4 , and applies the voltage E 1 to the load,
the controller generates a voltage E 2 from the second direct-current power supply V 2 by controlling the switching element S 21 , the switching element S 22 , the first common switching element S 3 , and the second common switching element S 4 , and applies the voltage E 2 to the load,
the controller generates a voltage differential voltage (E 1 −E 2 ) between the first direct-current power supply V 1 and the second direct-current power supply V 2 by controlling the switching element S 11 , the switching element S 12 , the switching element S 21 , and the switching element S 22 , while turning off the first common switching element S 3 and the second common switching element S 4 , and generates the differential voltage (E 1 −E 2 ) to the load, and
the controller generates the pseudo sine wave and applies the pseudo sine wave to the load by alternately applying the voltage E 1 , the voltage E 2 , and the differential voltage (E 1 −E 2 ).
2. The inverter according to claim 1 , wherein
the controller generates the differential voltage (E 1 −E 2 ) between the first direct-current power supply V 1 and the second direct-current power supply V 2 and applies the differential voltage (E 1 −E 2 ) to the load, either by:
turning on the switching element S 11 and the switching element S 22 and turning off the switching element S 12 and the switching element S 21 , while turning off the first common switching element S 3 and the second common switching element S 4 ; or
turning on the switching element S 12 and the switching element S 21 and turning off the switching element S 11 and the switching element S 22 , while turning off the first common switching element S 3 and the second common switching element S 4 .
3. The inverter according to claim 1 , wherein the voltage E 1 and the voltage E 2 are related to each other such that E 1 >E 2 .
4. The inverter according to claim 3 , wherein the controller generates the pseudo sine wave by changing an output voltage in the order of a null voltage, the differential voltage (E 1 −E 2 ), the voltage E 2 , and the voltage E 1 during a period from a phase 0 to a phase π/2 of the alternating-current voltage output, that is, a 1/4 cycle.
5. The inverter according to claim 4 , comprising the first direct-current power supply V 1 and the second direct-current power supply V 2 , wherein
denoting an area enclosed by a sine wave from a phase 0 to a phase π/2, an x axis, and x=π/2 as S 1 , and
denoting an area enclosed by the pseudo sine wave, the x axis, and x=π/2 as S 2 ,
the first direct-current power supply V 1 and the second direct-current power supply V 2 meet a ratio between the voltage E 1 and the voltage E 2 that minimizes a difference between the area S 1 and the area S 2 .