Overheat protection control device and vehicle-mounted power circuit device
A plurality of semiconductor elements have sources which are commonly connected, and drains which are commonly connected. A voltage measurement unit measures an ON voltage between the source of a first semiconductor element of the plurality of semiconductor elements and the drain of the first semiconductor element. A determination unit receives information indicating a magnitude of an ON current between the source of the first semiconductor element and the drain of the first semiconductor element, and a measured value of the ON voltage in the voltage measurement unit, and determines whether the plurality of semiconductor elements are in a normal state or in an overheated state based on the measured value of the ON voltage and the received information indicating the magnitude of the ON current.
1. An overheat protection control device for a device including a plurality of semiconductor elements whose sources are commonly connected and whose drains are commonly connected, comprising:
a voltage measurement unit configured to measure an ON voltage between the source of a first semiconductor element of the plurality of semiconductor elements and the drain of the first semiconductor element;
a storage unit configured to store information indicating relation between a temperature of the first semiconductor element and both of the ON voltage and an ON current between the source of the first semiconductor element and the drain of the first semiconductor element; and
a determination unit configured to receive information indicating a magnitude of the ON current, and a measured value of the ON voltage in the voltage measurement unit, refer to the information within the storage unit, specify a temperature corresponding to the measured value of the ON voltage and the magnitude of the ON current indicated by the received information, and determine whether the plurality of semiconductor elements are in a normal state or in an overheated state based on the temperature.
2. The overheat protection control device according to claim 1 , comprising a control unit configured to output a control command value commanding a value of the ON current, wherein
the determination unit is configured to receive the control command value as the information indicating the magnitude of the ON current.
3. The overheat protection control device according to claim 1 , comprising a current measurement unit configured to measure the ON current, wherein
the determination unit is configured to receive a measured value of the ON current as the information indicating the magnitude of the ON current.
4. The overheat protection control device according to claim 1 , wherein
the drains of the plurality of semiconductor elements are connected to a metal pattern on a substrate via a bonding material, and
the overheat protection control device comprises:
a plurality of first metal wires configured to connect the sources of the plurality of semiconductor elements and a terminal block; and
a second metal wire configured to connect a portion close to the first semiconductor element on the pattern and the terminal block.
5. The overheat protection control device according to claim 1 , comprising a filter unit configured to remove noise, at a preceding stage of an output terminal of the voltage measurement unit.
6. The overheat protection control device according to claim 1 , wherein the voltage measurement unit is configured to detect reduction of the ON voltage and perform short circuit protection for the semiconductor elements.
7. The overheat protection control device according to claim 1 , wherein the plurality of semiconductor elements are made of a compound semiconductor, and a temperature sensor is not placed on any of the plurality of semiconductor elements.
8. A vehicle-mounted power circuit device comprising a three-phase inverter to which the overheat protection control device according to claim 7 is applied.
9. The overheat protection control device according to claim 1 , wherein the information within the storage unit includes relation between the temperature of the first semiconductor element and both of the ON voltage and the ON current in a large current region.
10. An overheat protection control device for a device including a plurality of semiconductor elements whose sources are commonly connected and whose drains are commonly connected, comprising:
a voltage measurement unit configured to measure an ON voltage between the source of a first semiconductor element of the plurality of semiconductor elements and the drain of the first semiconductor element;
a storage unit configured to store information indicating relation between the ON voltage and both of a temperature of a cooler configured to cool the plurality of semiconductor elements and electric power output from a power conversion device including the plurality of semiconductor elements; and
a determination unit configured to refer to the information within the storage unit, specify an ON voltage corresponding to the temperature of the cooler detected at a certain time point and the electric power output from the power conversion device at the certain time point, and determine whether the plurality of semiconductor elements are in a normal state or in an overheated state based on the specified ON voltage and a measured value of the ON voltage.