To provide a steering torque detection device and steering torque detection method which can detect steering torque without employing a torque sensors, and an electric power steering device which can construct a duplex system without using a plurality of torque sensors.
A period of detection signal S1 of a motor rotational angle sensor 13 and a period of a detection signal S2 of a steering angle sensor 18 are respectively counted to calculate respective absolute angles. Further, steering torque T0 is calculated from relative angles of the absolute angles. A failure of a torque sensor 3 is detected by comparing a calculated steering torque T0 with torque detection value Ti. When the torque sensor 3 is in a normal state, steering auxiliary control is executed by employing the torque detection value Ti. When the failure of the torque sensor 3 occurs, the steering auxiliary control is executed by employing the steering torque detection value T0 instead of the torque detection value Ti.
FUKUNAGA MASANAO
KUBOKAWA MINORU
ONO KOICHIRO
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