Inverter device for electric vehicle
An inverter device for an electric vehicle is configured to be mounted in the electric vehicle including an electric motor configured to generate power for traveling and drive the electric motor. The inverter device includes a multilevel inverter circuit including switching elements, a controller configured to control the switching elements, and temperature sensors configured to respectively detect temperatures of the switching elements. The multilevel inverter circuit includes combinations for outputting phase currents in a same phase and in a same direction as combinations to drive the switching elements. The controller is configured to, when the electric motor is in a locked state in which torque is output from the electric motor and the electric motor is non-rotatable, switch between the combinations of the switching elements to be driven, based on outputs of the temperature sensors.
1 . An inverter device for an electric vehicle, the electric vehicle comprising an electric motor configured to generate power for traveling, the inverter device being configured to be mounted in the electric vehicle and drive the electric motor, the inverter device comprising:
a multilevel inverter circuit comprising switching elements;
a controller configured to control the switching elements; and
temperature sensors configured to respectively detect temperatures of the switching elements, wherein
the multilevel inverter circuit comprises combinations for outputting phase currents in a same phase and in a same direction as combinations to drive the switching elements, and
the controller is configured to, when the electric motor is in a locked state in which torque is output from the electric motor and the electric motor is non-rotatable, switch between the combinations of the switching elements to be driven, based on outputs of the temperature sensors.
2 . The inverter device for the electric vehicle according to claim 1 , wherein
the switching elements comprise a first switching element and a second switching element,
the combinations comprise a first combination in which the first switching element is driven and the second switching element is not driven, and a second combination in which the first switching element is not driven and the second switching element is driven, and
the controller is configured to, in the locked state, switch between the first combination and the second combination at a ratio in which a temperature gradient of one of the first switching element and the second switching element having a larger temperature margin is larger than a temperature gradient of one of the first switching element and the second switching element having a smaller temperature margin.
3 . The inverter device for the electric vehicle according to claim 1 , wherein
the switching elements comprise a first switching element and a second switching element,
the combinations comprise a first combination in which the first switching element is driven and the second switching element is not driven, and a second combination in which the first switching element is not driven and the second switching element is driven, and
the controller is configured to, in the locked state, switch, when a temperature margin of the first switching element and a temperature margin of the second switching element are balanced, between the first combination and the second combination at a ratio in which the temperature gradient of the first switching element and the temperature gradient of the second switching element are balanced.
4 . The inverter device for the electric vehicle according to claim 3 , wherein
the controller:
comprises characteristics data representing the temperature gradient of the first switching element when the first switching element is driven in the first combination and the temperature gradient of the second switching element when the second switching element is driven in the second combination; and
is configured to control the multilevel inverter circuit in the locked state by using the characteristics data.
5 . The inverter device for the electric vehicle according to claim 4 , wherein the controller is configured to, when the controller drives the multilevel inverter circuit in a period other than the locked state, perform learning processing of updating the characteristics data based on the outputs of the temperature sensors.
6 . The inverter device for the electric vehicle according to claim 2 , wherein
the controller:
comprises characteristics data representing a temperature gradient of the first switching element when the first switching element is driven in the first combination and a temperature gradient of the second switching element when the second switching element is driven in the second combination; and
is configured to control the multilevel inverter circuit in the locked state by using the characteristics data.
7 . The inverter device for the electric vehicle according to claim 6 , wherein the controller is configured to, when the controller drives the multilevel inverter circuit in a period other than the locked state, perform learning processing of updating the characteristics data based on the outputs of the temperature sensors.