Power converter
OwnerHitoshi Haga, Sumikazu Matsunoinventors
Life of this patent
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Abstract
In a power converter including a V connection inverter circuit, harmonic components included in output voltage are reduced to achieve a reduction in a loss of a load, such as a motor. Operation of four switching elements (a3 to 3d) of a V connection inverter circuit (3) is controlled so that the locus of a flux vector λp on a complex plane created by using voltage vectors Vp obtained by the operation of the switching elements (3a to 3d) approaches to a circle. Specifically, in order to create the locus of the flux vector λp close to a circle by using at least three of the four voltage vectors Vp, output sequences and output periods of the voltage vectors Vp are determined.
Claims12
A power converter including a capacitor circuit (2) which includes a plurality of capacitors (2a, 2b) connected in series to each other and which is capable of charging and discharging a DC voltage, and an inverter circuit (3) of which two switching legs (leg1, leg2) connecting respective two switching elements (3a, 3b, 3c, 3d) in series are connected in parallel to the capacitor circuit (2), where intermediate points of the switching legs (leg1, leg2) of the inverter circuit (3) are connected to the load (5), and an intermediate potential point of the capacitor circuit (2) is connected to the load (5), thereby converting DC power of the capacitor circuit (2) to AC power to supply the AC power to the load (5), the power converter, comprising:
- switching control means (4) which controls the operation of the switching elements (3a, 3b, 3c, 3d) of the inverter circuit (3) so that a locus of a flux vector (λp) created on a complex plane by using voltage vectors (Vp) obtained by operation of the switching elements (3a, 3b, 3 c, 3d) approaches to a circle.
A power converter, comprising
- a capacitor circuit (12) which includes a plurality of capacitors (12a, 12b) connected in series to each other and which is capable of charging and discharging a DC voltage;
- an inverter circuit (13) of which three switching legs (leg1, leg2, leg3) connecting respective two switching elements (13a, 13b, 13c, 13d, 13e, 13f) in series are connected in parallel to the capacitor circuit (12);
- a switching circuit (16) which is connected between an intermediate potential point of the capacitor circuit (12) and an intermediate point of one (leg1) of the switching legs;
- switching circuit control means (14b) which turns on the switching circuit (16) when a load (15) is low to set the inverter circuit (13) in a two-phase connection, and which turns off the switching circuit (16) when the load (15) is high to set the inverter circuit (13) in a three-phase connection;
- and
- switching control means (14a) which controls the operation of the switching elements (13a, 13b 13c, 13d, 13e, 13f) of the inverter circuit (13), when the switching circuit control means (14b) turns on the switching circuit (16), so that a locus of a flux vector λp on a complex plane created by using at least three voltage vectors of four voltage vectors (V0, V1, V2, V3) obtained by the operation of the switching elements (13a, 13b, 13c, 13d, 13e, 13f) in one cycle of a carrier frequency approaches to a circle.
Dependencies are inferred from the claim text.