Abstract: An electric power steering apparatus that performs steering assist by transmitting a driving force produced by an electric motor to a steering mechanism. The apparatus is provided with a current detection circuit for detecting a current flowing through the electric motor to output a motor current detection signal, and a microcomputer for controlling the electric motor on the basis of the motor current detection signal. The current detection circuit has a variable gain amplification circuit, to output the motor current detection signal amplified by the variable gain amplification circuit. The microcomputer has an analog-to-digital conversion port to which the motor current detection signal outputted by the current detection circuit is inputted, to receive the motor current detection signal through the analog-to-digital conversion port. The apparatus is further provided with a gain change section for changing the gain of the variable gain amplification circuit.

Abstract: For providing a hysteresis characteristic setting device configured by components smaller in number than those of a logic circuit or a comparator circuit for setting a hysteresis characteristic, the device comprises a resistor voltage dividing circuit including two resistors; and a microcomputer including first and second ports and serving as input ports. When an output signal from a low-pass filter circuit is supplied to the device, the voltage of the signal is divided by the two resistors of the resistor voltage dividing circuit and then given to the second port. The microcomputer performs a process according to a combination of levels Hi and Lo detected in the ports, to set a hysteresis characteristic in which an input voltage level corresponding to a threshold voltage level of the first port is a lower limit, and that corresponding to a threshold voltage level of the second port is an upper limit.

Abstract: An electric power steering apparatus for assisting the steering force of a steering member by an electric motor (18) driven by a driving circuit (13) connected to a power supply (P) by power connecting means (15a). The electric power steering apparatus comprising: means (12) for detecting a short-circuit failure on the driving circuit (13) and on a wiring connecting the driving circuit (13) and the electric motor (18); power off means (15) for turning off the power connecting means (15a) when a short circuit failure is detected; current detecting means (17) for detecting the value of a current flowing between the electric motor (18) and the driving circuit (13) after the power off means (15) turns off the power connecting means (15a); and current cutting means (Fa, Fb) for, when the current detecting means (17) detects a current value exceeding a predetermined value, irreversibly cutting off the current whose current value exceeds the predetermined.

Abstract: An electric power steering apparatus that performs steering assist by transmitting a driving force produced by an electric motor to a steering mechanism. The apparatus is provided with a current detection circuit for detecting a current flowing through the electric motor to output a motor current detection signal, and a microcomputer for controlling the electric motor on the basis of the motor current detection signal. The current detection circuit has a variable gain amplification circuit, to output the motor current detection signal amplified by the variable gain amplification circuit. The microcomputer has an analog-to-digital conversion port to which the motor current detection signal outputted by the current detection circuit is inputted, to receive the motor current detection signal through the analog-to-digital conversion port. The apparatus is further provided with a gain change section for changing the gain of the variable gain amplification circuit.

Abstract: For providing a hysteresis characteristic setting device configured by components smaller in number than those of a logic circuit or a comparator circuit for setting a hysteresis characteristic, the device comprises a resistor voltage dividing circuit including two resistors; and a microcomputer including first and second ports and serving as input ports. When an output signal from a low-pass filter circuit is supplied to the device, the voltage of the signal is divided by the two resistors of the resistor voltage dividing circuit and then given to the second port. The microcomputer performs a process according to a combination of levels Hi and Lo detected in the ports, to set a hysteresis characteristic in which an input voltage level corresponding to a threshold voltage level of the first port is a lower limit, and that corresponding to a threshold voltage level of the second port is an upper limit.

Abstract: An electric power steering apparatus for assisting the steering force of a steering member by an electric motor (18) driven by a driving circuit (13) connected to a power supply (P) by power connecting means (15a). The electric power steering apparatus comprising: means (12) for detecting a short-circuit failure on the driving circuit (13) and on a wiring connecting the driving circuit (13) and the electric motor (18); power off means (15) for turning off the power connecting means (15a) when a short circuit failure is detected; current detecting means (17) for detecting the value of a current flowing between the electric motor (18) and the driving circuit (13) after the power off means (15) turns off the power connecting means (15a); and current cutting means (Fa, Fb) for, when the current detecting means (17) detects a current value exceeding a predetermined value, irreversibly cutting off the current whose current value exceeds the predetermined.