| 摘要 |
PROBLEM TO BE SOLVED: To exactly grasp the heating condition of a motor drive circuit from a drive average current value and the time of a current flowing, and enable the drive of a device to the condition where the heat guarantee is possible, by detecting the drive current correlated to the heat generation of the motor drive circuit, and computing the drive average current. SOLUTION: The average value (drive average current value) of drive currents 3 in the time width gotten from the heat time constant of a motor drive circuit 2 is obtained. The current where the motor drive circuit 2 does not generate thermal influence such as heat breakdown, etc., is made the specified current value, and the time until its not causing heat breakage with the quantity of a current where the average drive current value is over the specified current value is made the set time. Then, the time of a current, where the average drive current value is over the specified current value, flowing continuously and the specified time are compared, and when the time of the average drive current value being over the specified current value gets over the set time, the motor drive circuit 2 is stopped, or applied voltage 12 is switched from the high-voltage output A of a DC/DC inverter 10 over to the low- voltage output of direct BAT6. |
