| 摘要 |
<p>PURPOSE:To detect the overload of a motor accurately as well as rapidly so as to protect the motor from overloading by providing a means for obtaining the temperature of the motor on the basis of the winding resistance of the motor and for lowering the driving current of the motor when the temperature reaches the fixed value. CONSTITUTION:The current IM, the terminal voltage VM and the engine speed NM of a motor 4 are read by a reading means, and the electromotive force VG of the motor 4 is obtained by an arithmetic means on the basis of the engine speed NM. The winding resistance RM of the motor 4 is further obtained by a resistance enumerating means 6 using the current IM, the terminal voltage VM and the electromotive force VG. The temperature of the motor 4 is also obtained by a temperature enumerating means from the winding resistance RM and the temperature coefficient of the winding. When the temperature of the motor reaches the fixed value, the driving current of the motor 4 is lowered.</p> |
