A fault detection method for a multi-phase motor system applies a first duty cycle to first phase coil windings and applies a second duty cycle to second phase coil windings. The second duty cycle differs from the first duty cycle by a first difference value D1. A first current I1 is measured. A third duty cycle is applied to third phase coil windings and a fourth duty cycle is applied to the second phase coil windings. The fourth duty cycle differs from the third duty cycle by a second difference value D2. A second current I2 is measured. Line-to-line resistances R1, R2 are calculated using the difference values D1, D2, the measured currents 11, I2, and a measured DC voltage VDC. After determining a resistance difference R between the line-to-line resistances R1, R2, a comparison to a first non-zero threshold T1 indicates a fault.

A power electronics unit for driving an electric machine excited by permanent magnets and including a rotor and a stator having at least one stator winding, comprising at least one power switch designed to drive the stator winding, and an overvoltage protection device to protect the power switch from overvoltage. The overvoltage protection device comprises a phase voltage detecting device associated with the power switch as well as a short-circuit switching circuit which, when a predetermined phase voltage threshold value of the phase voltage detected by the phase voltage detection device is reached or exceeded, is adapted to be activated for short-circuiting the stator winding associated with the power switch. The short-circuit switching circuit comprises the power switch designed to drive the stator winding.

A motor drive circuit for use in driving a motor having two or more phases comprising a motor bridge having, for each phase of the motor, a bridge arm comprising an upper switch and a lower switch that in normal operation may be opened and closed to modulate the voltage applied to the respective phases in response to drive signals from a motor control circuit, at least one solid state phase isolation relay that is provided in series in an electrical path connecting a respective phase of the motor to a respective bridge arm, the relay being closed in normal operation so that current can flow in the phase and is held open in a fault mode of operation to prevent the flow of current in the phase. The circuit also includes monitoring means for monitoring the current waveform in the phase to provide, at least in a fault mode of operation, an output indicative of when it is safe to open the SSPIR without causing damage due to the SSPIR due to an avalanche mode, and a control circuit that during normal operation applies a voltage to each device that is sufficient to hold the SSPIR closed and which, in the fault mode of operation, responds to the output of the monitoring means to reduce the voltage applied to each SSPIR to a level that causes the SSPIR to open at the safe time.

A method and device for operating a brushless electric motor, having windings controlled by an inverter using six switches. The inverter includes three outputs that are associated with the windings of the electric motor. A respective power semiconductor switch is arranged between the outputs of the inverter and the windings, and wherein a detection unit detects defective switches, a measuring unit measures the voltage at the outputs of the inverter, and a motor angle position sensor determines the motor angle position arc. The invention further relates to a device for operating a brushless electric motor. The inverter is switched off after a defective switch has been detected, such that no additional power is introduced in the windings of the electric motor. The motor angle position sensor consecutively opens the power semiconductor switches in a predetermined motor angle position.

A method for limiting the current in a device of H-bridge type having a plurality of transistors including the following steps: detection of a failure in a transistor from among the plurality of transistors; disabling of the transistor in which a failure has been detected; detection in the transistors opposite to the transistor, of the discharging of the energy accumulated at output; and disabling of the other transistors of the plurality of transistors. A system for limiting the current in a device of H-bridge type having a plurality of transistors is also disclosed.

The present disclosure provides a motor drive device. The motor drive device includes a current detection unit, a control unit and a determination unit. The current detection unit detects a current flowing through a motor coil. The control unit executes a slow attenuation mode that attenuates the current after an end of a power supply mode. The determination unit determines whether the current at a second time point while a predetermined time has elapsed from a first time point when the power supply mode is switched to a slow decay mode is below a limit value. When the determination unit determines that the current does not fall below the limit value, the control unit is configured to switch from the slow attenuation mode to a fast attenuation mode at the second time point.

The present disclosure relates to inter-phase short-circuit detection, and particularly, to a method and apparatus for detecting inter-phase short-circuit of a three-phase motor, and an air conditioner including the same. The apparatus for detecting inter-phase short-circuit of a three-phase motor includes: a power supply for rectifying AC power to supply DC power; an inverter for generating three-phase current for driving the three-phase motor using the DC power, the inverter including a plurality of switching elements including high-side switching elements and low-side switching elements corresponding to three phases, and a current sensor commonly connected to the switching elements; a gate driver for driving the plurality of switching elements; and a controller for controlling the gate driver such that current flowing through the high-side switching elements and current flowing through the low-side switching elements partially short-circuit to sense a current flowing through the current sensor and determine inter-phase short-circuit.

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.

An apparatus with load dump protection incorporates first and second half-bridge circuits, first and second comparators, and first and second clamping circuits. The first comparator compares a supply voltage with a first set voltage and generates a first comparison signal while the supply voltage exceeds the first set voltage. The second comparator compares the supply voltage with a second set voltage and generates a second comparison signal while the supply voltage exceeds the second set voltage. The first clamping circuit divides the supply voltage and provides a divided voltage to the first half-bridge circuit in response to the second comparison signal. The second clamping circuit divides the supply voltage and provides a divided voltage to the second half-bridge circuit in response to the second comparison signal.

An electrical circuit for driving at least one electric motor, the at least one motor having at least one set of phases windings. The electrical circuit is arranged as at least one lane comprising a motor drive circuit that is operable in use to supply drive voltages to one of the sets of phase windings of the motor. A reverse battery protection circuit is provided for at least one lane and is located in either a feed to the motor drive circuit from a power supply or in a return path from the motor drive circuit to the power supply. The reverse battery protection circuit comprises a switch which is normally open when the battery is disconnected and which remains open in the event that the battery is connected in error with a reverse polarity to the drive circuit. The electrical circuit also includes a control means which is arranged to control the switch of the reverse battery protection circuit so as to close the switch in the event that the control means determines that the battery is connected with the correct polarity. The switch is also opened during operation of the motor in the event that that one or more additional conditions are met.