The invention results in improved switching from the idling mode to an active short circuit mode of an electric machine. According to the invention, the switch from the idling mode to the active electric short circuit mode is delayed until predefined voltage conditions have been reached on the external terminals of an electric machine or until the rotor of the electric machine is in a predetermined position corresponding to the required voltage conditions.

The invention results in improved switching from the idling mode to an active short circuit mode of an electric machine. According to the invention, the switch from the idling mode to the active electric short circuit mode is delayed until predefined voltage conditions have been reached on the external terminals of an electric machine or until the rotor of the electric machine is in a predetermined position corresponding to the required voltage conditions.

In a motor driving apparatus including an inverter connectable to n motors (n being an integer not less than 2) each including a rotor having a permanent magnet, braking operation is performed on i (i being an integer from 1 to n−1) of the n motors, and then braking operation is performed on j (j being an integer from 1 to n−i) of the n motors other than the i motors. It is possible to reduce the risks of failure of the inverter and demagnetization of the motors due to overcurrent by reducing current flowing through the inverter and the motors when the braking operation is performed.

In some embodiments, an inverter control apparatus and a method for controlling the same are provided. The inverter control apparatus may speed up the discharging of the residual energy at an inverter driven with an input power when a safety signal is input to the inverter. The inverter control apparatus may include an input power switchgear supplying an input power to the inverter according to switching operation; an I/O unit inputting a safety signal to the inverter according to a user control input and outputting a failure output relay signal to the input power switchgear when the safety signal is generated; and a controller performing speeding up the discharge of residual energy at the inverter when the input power is interrupted.

In some embodiments, an inverter control apparatus and a method for controlling the same are provided. The inverter control apparatus may speed up the discharging of the residual energy at an inverter driven with an input power when a safety signal is input to the inverter. The inverter control apparatus may include an input power switchgear supplying an input power to the inverter according to switching operation; an I/O unit inputting a safety signal to the inverter according to a user control input and outputting a failure output relay signal to the input power switchgear when the safety signal is generated; and a controller performing speeding up the discharge of residual energy at the inverter when the input power is interrupted.

A method for operating switching elements of an inverter of a vehicle that is driven by way of a three-phase synchronous machine. The inverter has a series circuit of switching elements for the phases. When the vehicle brakes, the synchronous machine is used to set a cycle rate for the operation of the switching elements depending on a frequency of AC phase currents of the synchronous machine. The electrical energy provided by the synchronous machine is fed to a DC voltage intermediate circuit. The cycle rate is set according to the frequency of the AC phase currents, such that it corresponds to the frequency of the respective AC phase currents of the synchronous machine. Zero points of the AC phase currents are determined, and the switching elements are operated to set a predefined phase difference between the respective AC phase current and a respectively associated AC phase voltage.

A method for operating switching elements of an inverter of a vehicle that is driven by way of a three-phase synchronous machine. The inverter has a series circuit of switching elements for the phases. When the vehicle brakes, the synchronous machine is used to set a cycle rate for the operation of the switching elements depending on a frequency of AC phase currents of the synchronous machine. The electrical energy provided by the synchronous machine is fed to a DC voltage intermediate circuit. The cycle rate is set according to the frequency of the AC phase currents, such that it corresponds to the frequency of the respective AC phase currents of the synchronous machine. Zero points of the AC phase currents are determined, and the switching elements are operated to set a predefined phase difference between the respective AC phase current and a respectively associated AC phase voltage.

Disclosed is a disconnection detection apparatus of a sinusoidal wave signal. The disconnection detection apparatus of the present disclosure converts a first sinusoidal wave and a second sinusoidal wave into absolute values, respectively, and determines that disconnection occurs when a value of the first sinusoidal wave is less than a first comparison value that is greater than a minimum value and a value of the second sinusoidal wave is less than a second comparison value that is less than a maximum value.

Disclosed is a disconnection detection apparatus of a sinusoidal wave signal. The disconnection detection apparatus of the present disclosure converts a first sinusoidal wave and a second sinusoidal wave into absolute values, respectively, and determines that disconnection occurs when a value of the first sinusoidal wave is less than a first comparison value that is greater than a minimum value and a value of the second sinusoidal wave is less than a second comparison value that is less than a maximum value.

An electric working machine comprises a motor, a switch, a drive device, a brake device, and a failure determiner. The switch is configured for operation by a user, has an on-state and an off-state. The drive device is configured to drive the motor in response to the switch being placed in the on-state. The brake device is configured to control deceleration of the motor to a stopped state in response to the switch being placed in the off-state. The failure determiner is configured to monitor deceleration of the motor during controlled deceleration and to determine whether the brake device has failed based on the monitored deceleration.