To provide an overload protection device for motors capable of performing overload detection without providing many temperature detection means, reducing a margin of an overload protection setting value, and utilizing the motor performance sufficiently even in the case that the overload occurs at a specific position and phase.
Operation stop time temperature storage means 13 stores an operation stop time according to an absolute time at the time when a power supply switch 6 is turned off, and a base part temperature at this time. Re-operation start time temperature calculation means 14 calculates a cooling temperature during operation stop, and calculates a base part temperature at the time of re-operation start. Heat generation source current temperature calculation means 15 calculates a current temperature of each heat generation source generating heat by a motor current flowing in each pole coil 2a by using the base part temperature at the time of re-operation start. Overload determination means 16 determines that the overload occurs when the current temperature of each heat generation source reaches an overload protection setting value defined for each heat generation source.
SATO TOMONORI
| JPH11262289A | 1999-09-24 | |||
| JP2005204358A | 2005-07-28 | |||
| JPH11347889A | 1999-12-21 | |||
| JP2003094290A | 2003-04-03 |
Shuji Sugimoto
Kenro Tsutsumi
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