Abstract: A wiper system 1 has wiper blades 4a and 4b driven by a wiper motor 7 and washer nozzles 16 for ejecting washer liquid in association with operation of a washer motor 18. The wiper motor 7 and the washer motor 18 are drive-controlled by a controller 9 housed in a motor unit 6. The controller 9 uses a FET module 10 for a three-phase motor provided with seven FETs. In the FET module 10, a battery reverse connection protection part 31 is provided with one FET (34a), a wiper motor drive part 32 is provided with four FETs (34b to 34e), and a washer motor drive part 33 is provided with two FETs (34f and 34g).

Abstract: A motor speed, duty, and power source voltage are detected (steps S1 to S3). Referring to a load point map, a load point value is obtained (steps S4 and S5). The load point map is created with the motor speed, duty, and power source voltage taken as parameters, and is corrected in accordance with atmospheric temperature of the motor. After the load point value is obtained, the value is accumulated (step S6). The accumulated point value and a predetermined threshold value are compared with each other (step S7). If the accumulated point value exceeds the threshold value, an overloaded state is determined and the accumulated point value is stored (step S8). Thereafter, the motor is stopped.

Abstract: A motor speed, duty, and power source voltage are detected (steps S1 to S3). Referring to a load point map, a load point value is obtained (steps S4 and S5). The load point map is created with the motor speed, duty, and power source voltage taken as parameters, and is corrected in accordance with atmospheric temperature of the motor. After the load point value is obtained, the value is accumulated (step S6). The accumulated point value and a predetermined threshold value are compared with each other (step S7). If the accumulated point value exceeds the threshold value, an overloaded state is determined and the accumulated point value is stored (step S8). Thereafter, the motor is stopped.