| 摘要 |
<p>PURPOSE:To improve operating precision by calculating the junction temperature of switching elements based on the temperature of a radiating plate and the ambient temperature, and reducing the motor current value when this temperature exceeds the present value in an electric power steering device for a vehicle. CONSTITUTION:The temperature of a radiating plate is detected by a thermistor 23, the ambient temperature is detected by a thermistor 24, and they are inputted to a junction temperature calculating means 11b. The junction temperature calculating means 11b calculates the junction temperature of switching elements 15-18 based on the inputted information and the radiation equivalent circuit of switching elements 15-18. When the junction temperature exceeds the preset value, a relay 14 is excited via a relay drive section 25, and the excitation of a steering motor 6 is stopped. The malfunction of switching elements 15-18 can be prevented.</p> |
