| 摘要 |
PROBLEM TO BE SOLVED: To maintain the energizing level of a motor as high as possible by lowering the current value supplied to an electric coil through energization instructing means when the difference between the upper limit temperature value and the detected internal temperature of an element becomes a set value or lower. SOLUTION: In order to energize electric coils 1a-1c, energization instructing means 11 and 15-17 which give energization instructing signals to a switching module IPM and a gate driver GD are provided. Firstly, the saturated temperature of an element which is reached due to the heat generated from the power loss resulting from the energization when the energization is continued is calculated. Then the internal temperature of the element is calculated by assuming that a temperature rise caused by an increase in quantity of heat occurs with a time lag after the increase occurs by using the time constant of the saturated temperature and the temperature rise caused by the heat. On the other hand, when the difference between the upper limit temperature value and detected internal temperature of the element becomes a set value or lower, the values of currents supplied for energizing the coils 1a-1c are lowered through the energization instructing means 11 and 15-17 and gate driver GD in such a way that the current values are lowered more largely as the difference becomes smaller. |
