Power conversion device and semiconductor device

A power conversion device comprising:

• a power transistor including a control input terminal, a first terminal, and a second terminal, which supplies electric power to a predetermined load through the first terminal and the second terminal;
• a driver device;
• and
• a control device including a temperature estimation unit, which controls on and off of the power transistor through the driver device,
• wherein the driver device includes
• a driver that drives the control input terminal,
• a voltage detection circuit that detects an inter-terminal voltage of the first terminal and the second terminal during an on-period of the power transistor,
• a current detection circuit that detects an inter-terminal current of the first terminal and the second terminal during the on-period of the power transistor, and
• a temperature calculation circuit that calculates an on-resistance of the power transistor, based on the inter-terminal voltage detected by the voltage detection circuit and the inter-terminal current detected by the current detection circuit, hence to estimate a junction temperature,
• wherein the temperature estimation unit previously holds correlation information between the inter-terminal voltage and inter-terminal current of the first terminal and second terminal and the junction temperature, and estimates the junction temperature, based on the inter-terminal voltage obtained from the voltage detection circuit, a known inter-terminal current, and the correlation information
• wherein the power transistor includes:
• a driving transistor that supplies electric power to the predetermined load;
• and
• a current sensing transistor formed in a smaller size than the driving transistor and having the control input terminal and the second terminal in common with the driving transistor, and
• wherein the current detection circuit measures both-end voltage of a resistance element joined to the first terminal of the current sensing transistor.

A semiconductor device which drives a power transistor including a control input terminal, a first terminal, and a second terminal, for supplying electric power to a predetermined load through the first terminal and the second terminal, comprising:

• a driver that drives the control input terminal;
• a voltage detection circuit that detects an inter-terminal voltage of the first terminal and the second terminal during an on-period of the power transistor;
• a current detection circuit that detects an inter-terminal current of the first terminal and the second terminal during the on-period of the power transistor;
• and
• an overheat detection circuit that detects presence or absence of overheat in the power transistor,
• wherein the overheat detection circuit includes a temperature calculation circuit that calculates an on-resistance of the power transistor, based on the inter-terminal voltage detected by the voltage detection circuit and the inter-terminal current detected by the current detection circuit, to estimate a junction temperature,
• wherein the power transistor includes:
• a driving transistor that supplies electric power to the predetermined load;
• and
• a current sensing transistor formed in a smaller size than the driving transistor and having the control input terminal and the second terminal in common with the driving transistor, and
• wherein the current detection circuit measures both-end voltage of a resistance element joined to the first terminal of the current sensing transistor.