A circuit device includes an output circuit having a high-side transistor and a low-side transistor, and a control circuit configured to detect a voltage between the drain node and the source node of a detection target transistor that is at least one of the low-side transistor and the high-side transistor, and detect a malfunction in the case where it is determined that the detection voltage did not exceed a given comparison voltage.

A safety system has higher user design flexibility. Motor controllers (20, 30) include a motor drive circuit (207) that outputs a motor voltage command signal for driving motors (90, 100) in accordance with a motor drive command value, an inverter (211) that supplies power for driving the motors (90, 100) by switching based on the motor voltage command signal, a safety control unit that outputs a drive permission signal for driving the motors (90, 100) in accordance with communication data received through a communication circuit (213), a cut-off circuit (209) that receives the drive permission signal and the voltage drive command signal and cuts off the voltage drive command signal to an inverter (211) when receiving no drive permission signal, and a safety input unit (205) that receives redundant safety input signals. The cut-off circuit (207) receives a logical AND of the safety input signal and the drive permission signal.

A motor controller includes an inverter configured to convert a direct current to an alternating current, a control unit that generates a PWM signal for driving the inverter in response to a motor drive command from an external device, and a safety circuit arranged between the inverter and the control unit. The inverter includes an upper switching element and a lower switching element. The safety circuit includes logic gates which are provided corresponding to the upper switching element and the lower switching element, respectively and each of which has two or more inputs to cut off the PWM signal based on a safety input signal.

A system and a method of detecting and isolating a fault in an electric motor system are provided. The method includes detecting, at a motor drive electronics (MDE) component that is configured to drive an electric motor through a harnessing, the fault in the electric motor system, applying a voltage and current, at the MDE component, according to a gate switching sequence for all phases of the electric motor system in response to detecting the fault, sensing voltage and current values in the MDE component between switches of an inverter of the MDE component, and isolating the fault within the electric motor system based on the sensed voltage and current values.

A motor driving device includes an abnormality detecting portion arranged to detect an abnormality of one of a plurality of position detection signals based on outputs from a plurality of Hall sensors arranged to detect a rotor position of a brushless DC motor, a measuring portion arranged to measure time between neighboring edges of a normal position detection signal when the abnormality detecting portion detects an abnormality, and a drive control portion arranged to control a drive signal for driving the brushless DC motor based on a latest time measurement result of the measuring portion.

A vehicle driving device includes an inverter which drives a motor. The inverter includes: a three-phase bridge circuit including a plurality of switching elements; a three-phase short circuit which short-circuits three phases of the motor via the three-phase bridge circuit; and a control circuit. The control circuit includes: a microprocessor which drives the three-phase bridge circuit; a malfunction notification circuit which outputs a malfunction notification signal when the microprocessor is malfunctioning; and a latch circuit which holds the malfunction notification signal outputted from the malfunction notification circuit. The control circuit outputs a three-phase short-circuit drive signal which drives the three-phase short circuit, based on the malfunction notification signal held by the latch circuit.

A system for protecting an inverter in a vehicle from an overvoltage may include an inverter including a plurality of switching elements and converting energy supplied from an energy storage into AC power, a motor driven by the AC power converted by the inverter, a capacitor connected in parallel between the inverter and the energy storage and storing regenerative energy of the motor during regenerative braking, and a controller turning off a relay that connects the energy storage and the motor, when a voltage (DC-link voltage) of the capacitor measured by a voltage sensor is equal to or greater than a preset first voltage, and operating the switching elements in the inverter in response to a pre-stored current command (Id*, Iq*) to apply a zero vector to the motor.

MCU (2001) determines whether at least one of double three-phase inverter (2030) or battery (2002) has a failure, or battery (2002) is fully charged, and switches control to be performed in inverter (2030) between all-phase shut off and three-phase short circuit based on a motor rotation speed of double three-phase motor (2050) when MCU (2001) determines that any one of inverter (2030) and battery (2002) has a failure, or battery (2002) is fully charged. Battery (2002) and inverter (2030) can be protected when current is inhibited from flowing from motor (2050) to battery (2002) due to a failure of inverter (2030) or battery (2002).

A controller has an encoder that outputs four-phase pulse signals according to a rotation of a rotor of a motor by a rule. During a rotational drive of the motor, when (i) an abnormal pulse state is observed in which the pulse signal is output in a non-compliant manner with the rule and (ii) a lapse time from a last normal output timing, which is a last timing of an output of the pulse signal by the rule, is longer than a threshold determination time, it is conclusively determined that the encoder has abnormality. Thus, the encoder is provided with an improved noise-proof character, and is prevented from being falsely determined as abnormal due to the abnormal pulse state, even when an output of the pulse signal from the encoder is temporarily ridden by a noise.

A failure diagnostic apparatus for current sensors of a 3-phase brushless AC (BLAC) motor may include: a 3-phase BLAC motor; current sensors each configured to measure a phase current of the 3-phase BLAC motor; a motor driving unit configured to drive the 3-phase BLAC motor; and a control unit configured to drive the 3-phase BLAC motor through the motor driving unit, periodically calculate a phase current error using the phase current fed back through each of the current sensors, and diagnose that a failure occurred in the current sensor of the corresponding phase, when an error count accumulated during a preset time reaches a preset value, based on the phase current error.