An inverter controller is provided. The controller according to an exemplary embodiment of the present disclosure generates a compensation voltage to compensate an inverter command voltage using motor torque current and motor information, and apply the compensation voltage to the command voltage.

An electric working machine of an example of the present disclosure includes: a motor; a power supply portion; a controller; and a voltage detector. The power supply portion generates a DC voltage to drive the motor by rectifying an AC voltage supplied from an AC power source and smoothing by a capacitor. The controller controls energization of the motor. The voltage detector detects the AC voltage. The controller is configured to interrupt the energization when the voltage detector does not detect the AC voltage.

When a rotational difference is generated between a left driving wheel and a right driving wheel, by controlling the frequency f0 of alternating currents to be fed to stator windings of first and second induction machines by a shared inverter, torque distribution to the left driving wheel and the right driving wheel is controlled.

The present invention provides a method and a device for operating an electric machine for a soft changeover from a normal or free-wheel mode to an active short-circuit. To this end, a voltage with which the electric machine is actuated is first reduced in a defined manner to a predefined, preferably very low value and then the phase connections of the electric machine are short-circuited. Excessively high overcurrents, particularly overcurrents greater than the nominal current of the electric machine, can thus be avoided.

The present invention provides a method and a device for operating an electric machine for a soft changeover from a normal or free-wheel mode to an active short-circuit. To this end, a voltage with which the electric machine is actuated is first reduced in a defined manner to a predefined, preferably very low value and then the phase connections of the electric machine are short-circuited. Excessively high overcurrents, particularly overcurrents greater than the nominal current of the electric machine, can thus be avoided.

The present invention provides a device and a method for changing over an electric machine from the regular operating mode into the open-circuit mode. In order to avoid excessive increases in voltage and associated adverse effects on the electric machine and the other components, in particular batteries, a further control phase is introduced between the end of the regular operating mode and the freewheeling mode, during which further control phase the voltage at the terminals of the electric machine is continuously adjusted from the voltage previously set in the regular operating mode to the expected open-circuit voltage of the electric machine.

The present invention provides a device and a method for changing over an electric machine from the regular operating mode into the open-circuit mode. In order to avoid excessive increases in voltage and associated adverse effects on the electric machine and the other components, in particular batteries, a further control phase is introduced between the end of the regular operating mode and the freewheeling mode, during which further control phase the voltage at the terminals of the electric machine is continuously adjusted from the voltage previously set in the regular operating mode to the expected open-circuit voltage of the electric machine.

An electric vehicle that has: a DC power supply; an inverter; an inverter control circuit; a smoothing capacitor that is connected between input terminals of the inverter; a discharge circuit that discharges the smoothing capacitor; a control power supply that supplies electric power to the inverter control circuit; a holding capacitor that stores the electric power supplied from the control power supply and supplies the electric power to the inverter control circuit; and a collision detector that detects a collision of the vehicle. The collision detector transmits a first signal and a second signal that follows the first signal when detecting the collision. The inverter control circuit stops supplying the electric power to a switching element drive circuit when receiving the first signal. The inverter control circuit discharges the smoothing capacitor when receiving the second signal.

A motor drive system according to an embodiment includes an inverter and a control device. The inverter causes a current to flow through a winding of an induction motor. The control device drives the induction motor by controlling the inverter through vector control. The control device includes a plurality of calculation criteria for a stator magnetic flux estimated value of the induction motor and includes an appropriate magnetic flux command generation unit that selects a calculation criterion for the stator magnetic flux estimated value that further increases a loss of the induction motor from among the plurality of calculation criteria on the basis of at least a rotation speed of the induction motor in the case of braking the induction motor.

A motor drive system according to an embodiment includes an inverter and a control device. The inverter causes a current to flow through a winding of an induction motor. The control device drives the induction motor by controlling the inverter through vector control. The control device includes a plurality of calculation criteria for a stator magnetic flux estimated value of the induction motor and includes an appropriate magnetic flux command generation unit that selects a calculation criterion for the stator magnetic flux estimated value that further increases a loss of the induction motor from among the plurality of calculation criteria on the basis of at least a rotation speed of the induction motor in the case of braking the induction motor.