In a semiconductor device in the related art, it has been necessary to match the threshold voltage of a power element with the circuit operation of a gate driver; accordingly, it has been difficult to realize the operation of the gate driver most appropriate for the employed power element. According to one embodiment, when a power element is turned off, the semiconductor device monitors the collector voltage of the power element, and increases the number of NMOS transistors that draw out charges from the gate of the power element in a period until the collector voltage becomes lower than the pre-set determination threshold, rather than in the period after the collector voltage becomes lower than the determination threshold.

In a semiconductor device in the related art, it has been necessary to match the threshold voltage of a power element with the circuit operation of a gate driver; accordingly, it has been difficult to realize the operation of the gate driver most appropriate for the employed power element. According to one embodiment, when a power element is turned off, the semiconductor device monitors the collector voltage of the power element, and increases the number of NMOS transistors that draw out charges from the gate of the power element in a period until the collector voltage becomes lower than the pre-set determination threshold, rather than in the period after the collector voltage becomes lower than the determination threshold.

Provided is a power supply control device for controlling power supply to a motor installed in a vehicle, including: a switching element configured to turn on and off the power supply to the motor; a current detection circuit configured to detect a current flowing to the motor; and a control unit configured to determine whether or not the motor is in a locked state based on the current detected by the current detection circuit, and control turning on and off the power supply to the motor at a duty cycle that corresponds to the current detected by the current detection circuit, if it is determined that the motor is in the locked state.

A method of controlling a portable appliance includes measuring an input current supplied to a motor of the portable appliance and measuring a rotational speed of a shaft of the motor. The method also includes determining a current limit based on the rotational speed of the shaft using a substantially continuous function which relates a domain of rotational speeds to a range of current limits. The method further includes reducing, when the input current exceeds the current limit, the rotational speed of the shaft incrementally along the substantially continuous function until the input current is approximately equal to the current limit.

A method of controlling a portable appliance includes measuring an input current supplied to a motor of the portable appliance and measuring a rotational speed of a shaft of the motor. The method also includes determining a current limit based on the rotational speed of the shaft using a substantially continuous function which relates a domain of rotational speeds to a range of current limits. The method further includes reducing, when the input current exceeds the current limit, the rotational speed of the shaft incrementally along the substantially continuous function until the input current is approximately equal to the current limit.

A functional safety system with high reliability is provided. The functional safety system includes power source apparatuses VS1 and VS2, voltage monitoring apparatuses VM1 and VM2, semiconductor devices SC1 and SC2, interruption circuits IN1 and IN2, and a motor MT. A the voltage converting circuit DA1 of the voltage monitoring apparatus VM1 generates a detected voltage VA1 from a power source voltage VDD1 on the basis of a switching signal VC1, and a voltage converting circuit DA2 of the voltage monitoring apparatus VM1 generates a detected voltage VA2 from the power source voltage VDD1 on the basis of a switching signal VC1.

In an integrated circuit formed into a single chip, a drive signal generating unit generates drive signals for switching elements of a power conversion circuit. A monitoring unit monitors a microcomputer that calculates generation information that is information used to generate the drive signals, and determines whether or not an abnormality has occurred in the microcomputer. An angle converting unit converts an output signal of an angle sensor to rotation angle information of a rotating electric machine. A drive signal generating unit generates the drive signals for controlling driving of the rotating electric machine based on the generation information and the rotation angle information when the monitoring unit determines that an abnormality has not occurred in the microcomputer, and generates the drive signals based on the rotation angle information, without using the generation information, when the monitoring unit determines that an abnormality has occurred in the microcomputer.

In an integrated circuit formed into a single chip, a drive signal generating unit generates drive signals for switching elements of a power conversion circuit. A monitoring unit monitors a microcomputer that calculates generation information that is information used to generate the drive signals, and determines whether or not an abnormality has occurred in the microcomputer. An angle converting unit converts an output signal of an angle sensor to rotation angle information of a rotating electric machine. A drive signal generating unit generates the drive signals for controlling driving of the rotating electric machine based on the generation information and the rotation angle information when the monitoring unit determines that an abnormality has not occurred in the microcomputer, and generates the drive signals based on the rotation angle information, without using the generation information, when the monitoring unit determines that an abnormality has occurred in the microcomputer.

A control unit for driving a motor mainly includes an input circuit for inputting various kinds of information pieces, an output circuit for driving the coil windings of the motor, an MPU for calculating a control amount based on the information from the input circuit and outputting a control signal to the output circuit; the control unit has two pieces each of the input circuit, the output circuit, and the, and can supply respective electric currents to the windings of the motor or can cut off the supply; the MPUs each have a CPU incorporated therein, a trigger circuit for a trigger signal having a predetermined period; the two CPUs synchronize at least control commands in accordance with the trigger signal and output the control commands.

A closed-loop circuit is detected based on a short-circuit failure of a motor control switching element of a motor drive circuit and a cutoff switching element. A motor control device including a motor, a motor drive circuit (10a) that is connected to a power supply device and the motor and controls the output of the motor, and a processing unit for detecting a closed-loop circuit formed by the motor and the motor drive circuit (10a) based on a short-circuit failure of switching elements arranged in the motor drive circuit (10a).