To prevent the loss consumed by a current control means for performing control of a load current from exceeding an absolute rated value.
In the power control device in which an electric field effect transistor FET and a heater are connected to an on-vehicle battery in series, when a current ID flowing in the heater is gradually increased by FET (element voltage=VFET), if a heater voltage VH reaches to a first voltage V1 such that loss WD=ID×VFET of FET does not exceed allowance loss PD, i.e., a rated value, it is increased step-by-step to a second voltage V2 larger than it and thereafter VH is gradually increased again. Further, even at gradual reduction of ID, the VH is reduced step-by-step from V2 to V1. Thereby, the loss WD of FET does not exceed PD and the power of the heater can be gradually increased or decreased.
COPYRIGHT: (C)2007,JPO&INPIT
KATO YUKUSHI
TOYOTA MOTOR CORP
Takahiro Miura
Fumihiro Mizuno
Next Patent: WHEEL POSITION DETECTION DEVICE AND TIRE PRESSURE DETECTION DEVICE PROVIDED WITH IT