A control device for an electric motor includes: a controller configured to apply switching control to an inverter configured to execute power conversion in accordance with a torque command, to thereby control AC power to be supplied to the electric motor; and a current sensor configured to detect a phase current, which flows through an AC cable configured to connect the electric motor and the inverter to each other, wherein the controller includes a disconnection detection unit configured to acquire the phase current detected by the current sensor as a phase current detection value, calculate based on the torque command a phase current command value directed to the electric motor, and determine presence or absence of a disconnection of the AC cable in each phase from a transition result of a difference value between the phase current command value and the phase current detection value in each phase.

A control device for an electric motor includes: a controller configured to apply switching control to an inverter configured to execute power conversion in accordance with a torque command, to thereby control AC power to be supplied to the electric motor; and a current sensor configured to detect a phase current, which flows through an AC cable configured to connect the electric motor and the inverter to each other, wherein the controller includes a disconnection detection unit configured to acquire the phase current detected by the current sensor as a phase current detection value, calculate based on the torque command a phase current command value directed to the electric motor, and determine presence or absence of a disconnection of the AC cable in each phase from a transition result of a difference value between the phase current command value and the phase current detection value in each phase.

The disclosed embodiment relates to a method of controlling a system including at least one inverter with six switches, which is linked to a battery, and supervised by a processor. The method implements a vector modulation, so that it is able to prevent the current linking the battery from passing through zero amperes by means of appropriate control logic. The disclosed embodiment also relates to device for controlling an electronic component.

The disclosed embodiment relates to a method of controlling a system including at least one inverter with six switches, which is linked to a battery, and supervised by a processor. The method implements a vector modulation, so that it is able to prevent the current linking the battery from passing through zero amperes by means of appropriate control logic. The disclosed embodiment also relates to device for controlling an electronic component.

The object of the invention is a method of controlling a permanent-magnet synchronous or synchro-reluctant three-phase rotary machine (4), comprising the following steps: measuring a current (i.sub.A, i.sub.B, i.sub.C) flowing through each phase of a stator of rotary machine (4), first calculating, by use of a single proportional-integral controller, of a switching control signal for controlling an inverter (10), according to each measured current (i.sub.A, i.sub.B, i.sub.C), and of a target value (T.sub.ref) of a mechanical torque provided by the rotary machine (4) or of a target value of an angular speed of a rotor of rotary machine (4) in relation to the stator wherein the inverter (10) is configured to convey electrical energy between a continuous electrical energy source (8) and each phase of the stator of rotary machine (4), and controlling the inverter (10) by use of the calculated switching control signal.

The object of the invention is a method of controlling a permanent-magnet synchronous or synchro-reluctant three-phase rotary machine (4), comprising the following steps: measuring a current (i.sub.A, i.sub.B, i.sub.C) flowing through each phase of a stator of rotary machine (4), first calculating, by use of a single proportional-integral controller, of a switching control signal for controlling an inverter (10), according to each measured current (i.sub.A, i.sub.B, i.sub.C), and of a target value (T.sub.ref) of a mechanical torque provided by the rotary machine (4) or of a target value of an angular speed of a rotor of rotary machine (4) in relation to the stator wherein the inverter (10) is configured to convey electrical energy between a continuous electrical energy source (8) and each phase of the stator of rotary machine (4), and controlling the inverter (10) by use of the calculated switching control signal.

The present invention relates to a motor drive apparatus and, more particularly, to a motor drive apparatus capable of immediately restarting by maintaining sensorless control during a stop operation of a motor. The motor drive apparatus comprises: an inverter for driving a motor by using an AC voltage; and a control unit for controlling operations of a switching element included in the inverter. At this time, when a stop command is input, the control unit decreases a duty ratio of a PWM signal until a present speed of the motor becomes smaller than a predetermined minimum speed, thereby decreasing the revolutions per minute of the motor. Then, when a restart command is input in a state where the duty ratio of the PWM signal is decreased, the control unit can immediately restart the motor by increasing the duty ratio of the PWM signal.

The present invention relates to a motor drive apparatus and, more particularly, to a motor drive apparatus capable of immediately restarting by maintaining sensorless control during a stop operation of a motor. The motor drive apparatus comprises: an inverter for driving a motor by using an AC voltage; and a control unit for controlling operations of a switching element included in the inverter. At this time, when a stop command is input, the control unit decreases a duty ratio of a PWM signal until a present speed of the motor becomes smaller than a predetermined minimum speed, thereby decreasing the revolutions per minute of the motor. Then, when a restart command is input in a state where the duty ratio of the PWM signal is decreased, the control unit can immediately restart the motor by increasing the duty ratio of the PWM signal.

A controller of a power tool is configured to, based on a sampled current of a motor of the power tool, output control signals that change with a change of a position of a rotor of the motor to control a drive circuit of the power tool such that an input voltage and/or a current of the motor changes approximately in a sine wave.

A controller of a power tool is configured to, based on a sampled current of a motor of the power tool, output control signals that change with a change of a position of a rotor of the motor to control a drive circuit of the power tool such that an input voltage and/or a current of the motor changes approximately in a sine wave.