A motor control system shorts motor windings of a motor by using junction gate field-effect transistors (JFETs) controlled bipolar junction transistors (BJTs), solid state relays (SSRs) controlled BJTs, and depletion mode metal-oxide-semiconductor field-effect transistors (MOSFETs) so that the motor generates braking torque when all or some electric control units of the motor are disabled or failed. The motor control system comprises: a motor comprising a plurality of motor phase terminals; a plurality of electric control units electrically connected with the motor and configured to control the motor, wherein the electric control units are configured to output control signals, respectively; and a shorting circuit connected to between the motor and the electric control units, the shorting circuit configured to short the motor phase terminals in response to receiving none of the control signals from the electric control units. The shorting circuit is configured not to short the motor phase terminals when receiving at least one of the control signals from at least one of the electric control units.

A motor control system shorts motor windings of a motor by using junction gate field-effect transistors (JFETs) controlled bipolar junction transistors (BJTs), solid state relays (SSRs) controlled BJTs, and depletion mode metal-oxide-semiconductor field-effect transistors (MOSFETs) so that the motor generates braking torque when all or some electric control units of the motor are disabled or failed. The motor control system comprises: a motor comprising a plurality of motor phase terminals; a plurality of electric control units electrically connected with the motor and configured to control the motor, wherein the electric control units are configured to output control signals, respectively; and a shorting circuit connected to between the motor and the electric control units, the shorting circuit configured to short the motor phase terminals in response to receiving none of the control signals from the electric control units. The shorting circuit is configured not to short the motor phase terminals when receiving at least one of the control signals from at least one of the electric control units.

The invention relates to a method for deterring theft of a vehicle having a three-phase electric motor without a freewheel (10), comprising the steps of using the motor in a generator mode to power a motor control circuit (14) in an initial phase of rotating the motor through motion of the vehicle; and, when the power supply level of the control circuit reaches a first threshold (Vmin), connecting by the control circuit first and second phases (b, c) of the three-phase motor continuously to a first power supply line (Vss), whereby the first and second phases are short-circuited and cause an increased braking force of the motor. During this time, the third phase of the motor may be connected to continue to supply energy to the control circuit.

The invention relates to a method for deterring theft of a vehicle having a three-phase electric motor without a freewheel (10), comprising the steps of using the motor in a generator mode to power a motor control circuit (14) in an initial phase of rotating the motor through motion of the vehicle; and, when the power supply level of the control circuit reaches a first threshold (Vmin), connecting by the control circuit first and second phases (b, c) of the three-phase motor continuously to a first power supply line (Vss), whereby the first and second phases are short-circuited and cause an increased braking force of the motor. During this time, the third phase of the motor may be connected to continue to supply energy to the control circuit.

An air conditioning system including a compressor having a motor; a condenser; an evaporator; a drive providing multiphase, AC output to the motor; a motor braking assembly electrically connected to the drive, the motor braking assembly including at least one switch and at least one braking resistor; wherein the at least one switch is held in an open state by power from the drive; wherein upon disruption of power to the motor, the at least one switch assumes a closed state shorting windings of the motor through the at least one braking resistor.

A power converter according to an aspect of an embodiment includes: a diode converter; an inverter; a smoothing capacitor; a resistor; a current sensor; an estimation unit; and a control unit. The diode converter rectifies an alternating current from a power supply. The inverter is formed such that a DC side is connected to a DC output of the diode converter and an AC side is connected to an electric motor and includes a semiconductor switching element which converts DC power on the DC side into AC power and a reverse connection diode which is connected in antiparallel with the semiconductor switching element. The smoothing capacitor is provided in the DC output of the diode converter. The resistor is connected in parallel with the smoothing capacitor. The current sensor detects a load current flowing between the inverter and the electric motor. The estimation unit calculates an estimation value of the DC voltage Vdc on the DC side on the basis of a current value I detected by the current sensor. The control unit controls the inverter so that the estimation value of the DC voltage Vdc on the DC side does not exceed a predetermined reference voltage during a period in which the electric motor is in a regenerative state.

A motor braking procedure is controlled for an electric motor that provides a drive torque for a vehicle and is driven electrically by an inverter circuit having a plurality of switching elements via at least two motor connections and has a rotor rotateable at a motor speed. A braking switch position is adopted by the inverter circuit in braking switch position intervals. An open switch position is adopted by the inverter circuit in open switch position intervals. The braking switch position intervals are alternately switched with the open switch position intervals based on a motor speed being less than a limit speed during the motor braking procedure. The rotor, during the electric motor braking procedure, is subject to a speed-dependent braking torque based on the inverter circuit adopting a braking switch position and is subject to a braking torque less than that in the braking switch position or no braking torque based on the inverter circuit adopting an open switch position.

A motor braking procedure is controlled for an electric motor that provides a drive torque for a vehicle and is driven electrically by an inverter circuit having a plurality of switching elements via at least two motor connections and has a rotor rotateable at a motor speed. A braking switch position is adopted by the inverter circuit in braking switch position intervals. An open switch position is adopted by the inverter circuit in open switch position intervals. The braking switch position intervals are alternately switched with the open switch position intervals based on a motor speed being less than a limit speed during the motor braking procedure. The rotor, during the electric motor braking procedure, is subject to a speed-dependent braking torque based on the inverter circuit adopting a braking switch position and is subject to a braking torque less than that in the braking switch position or no braking torque based on the inverter circuit adopting an open switch position.

Braking a power tool motor based on a phase voltage of the motor. The power tool includes a motor and a power source providing operating power to the motor. A power switching network is between the power source and the motor to drive the motor. An actuator is operable to provide an input. An electronic controller is connected to the actuator and the power switching network. The electronic controller is configured to receive an indication related to initiating braking of the motor, control the power switching network to allow the motor to coast, monitor a phase voltage of the motor, determine whether the phase voltage of the motor is equal to or less than a phase voltage threshold, and control, in response to the phase voltage of the motor being equal to or less than the phase voltage threshold, the power switching network to brake the motor.

A method for operating an electrical circuit arrangement comprising an electrical circuit and an electrical machine, wherein when at least one triggering criterion is fulfilled the electrical machine is switched via the electrical circuit to a freewheeling, after which a time duration is determined in dependence on at least one measurement value describing a change in the stator current in the electrical machine, and the electrical machine is operated in the freewheeling for this duration and then it is switched via the electrical circuit to an active short circuiting.