An aspect of the disclosed invention calculates a value of an inductance of a synchronous motor whose characteristic is unclear while suppressing a failure of the synchronous motor. A motor driving device according to an embodiment of the disclosed invention comprises: a motor; an inverter for supplying an alternating voltage to the motor; a current meter for measuring an introduced current flowing through the motor on the basis of the alternating voltage; and a control unit for controlling the inverter to change the size of the alternating voltage in stages, and calculating an inductance of the motor on the basis of the introduced current measured by the current meter.

An aspect of the disclosed invention calculates a value of an inductance of a synchronous motor whose characteristic is unclear while suppressing a failure of the synchronous motor. A motor driving device according to an embodiment of the disclosed invention comprises: a motor; an inverter for supplying an alternating voltage to the motor; a current meter for measuring an introduced current flowing through the motor on the basis of the alternating voltage; and a control unit for controlling the inverter to change the size of the alternating voltage in stages, and calculating an inductance of the motor on the basis of the introduced current measured by the current meter.

A charging system is provided. The charging system includes an inverter, a wound rotor synchronous motor that has at least one stator coil supplied with power converted by the inverter and a rotor having a plurality of field coils, and a switching circuit unit that is configured to selectively supply power to the plurality of field coils. Additionally, a controller is configured to operate the switching circuit unit to supply power from the battery to at least one of the plurality of field coils when the wound rotor synchronous motor operates as a motor and isolate the field coils from the battery and operate the switching circuit unit to supply grid power to a portion of the field coils when the wound rotor synchronous motor is charging when the wound rotor synchronous motor supplies the grid power to the field coil side to charge the battery.

A charging system is provided. The charging system includes an inverter, a wound rotor synchronous motor that has at least one stator coil supplied with power converted by the inverter and a rotor having a plurality of field coils, and a switching circuit unit that is configured to selectively supply power to the plurality of field coils. Additionally, a controller is configured to operate the switching circuit unit to supply power from the battery to at least one of the plurality of field coils when the wound rotor synchronous motor operates as a motor and isolate the field coils from the battery and operate the switching circuit unit to supply grid power to a portion of the field coils when the wound rotor synchronous motor is charging when the wound rotor synchronous motor supplies the grid power to the field coil side to charge the battery.

A first offset voltage which is added to voltage commands in a first three-phase voltage command calculated on the basis of a control command for an AC rotary machine, and a second offset voltage which is added to voltage commands in a second three-phase voltage command calculated on the basis of a control command for the AC rotary machine, are set in such a manner that a period during which one of a first power converter and a second power converter outputs an effective vector and the other thereof outputs a zero vector occurs during a carrier period of a first carrier wave signal and a second carrier wave signal.

A load control device may control power delivered from a power source, such as an alternating-current (AC) power source, to at least two electrical loads, such as a lighting load and a motor load. The load control device may include multiple load control circuit, such as a dimmer circuit and a motor drive circuit, for controlling the power delivered to the lighting load and the motor load, respectively. The load control device may adjust the rotational speed of the motor load in a manner so as to minimize acoustic noise generated by the load control device and reduce the amount of time required to adjust the rotational speed of the motor load. The load control device may remain powered when one of the electrical loads (e.g., the lighting load) has been removed (e.g., electrically disconnected or uninstalled) and/or has failed in an open state (has burnt out or blown out).

According to one embodiment, a control system includes a chopper, a short-circuit unit, a voltage detector circuit, and a controller. The chopper reduces a direct current voltage between a converter connected to a stator in a wound induction machine and an inverter connected to a rotor in the wound induction machine. The short-circuit unit shorts a wire used for connection between the rotor and the inverter and the voltage detector circuit is to detect the direct current voltage. The controller causes driving the chopper and, at the same time, outputting from the inverter an alternating current over which a direct current component is superimposed when a voltage value exceeds a first predetermined value, and causes driving the short-circuit unit and, at the same time, halting the inverter when the voltage value exceeds a second predetermined value.

According to one embodiment, a control system includes a chopper, a short-circuit unit, a voltage detector circuit, and a controller. The chopper reduces a direct current voltage between a converter connected to a stator in a wound induction machine and an inverter connected to a rotor in the wound induction machine. The short-circuit unit shorts a wire used for connection between the rotor and the inverter and the voltage detector circuit is to detect the direct current voltage. The controller causes driving the chopper and, at the same time, outputting from the inverter an alternating current over which a direct current component is superimposed when a voltage value exceeds a first predetermined value, and causes driving the short-circuit unit and, at the same time, halting the inverter when the voltage value exceeds a second predetermined value.

An electric power control method comprising: a current measuring step; a command value calculating step; an operating step; a determining step of determining whether to change an operation period within which the operating step is performed so as to be longer than one cycle of the carrier wave or not; a first reducing step of reducing the switching operation of the switching elements in a first half cycle of the carrier wave starting from a start timing of the operation period after the change during which the carrier wave monotonously changes; a comparing step of changing a slope of the carrier wave in an intermediate period between the first half cycle of the carrier wave and a last half cycle of the carrier wave in the operation period after the change to compare the carrier wave with the duty command value in the magnitude, the comparing step performing the switching operation of the switching elements according to a result of the comparison; and a second reducing step of reducing the switching operation of the switching elements in the last half cycle of the carrier wave.

A device for the de-excitation of at least one rotor winding of an externally electrically excited synchronous motor has a stator current controller. The stator current controller is designed to inject a stator current value into a stator current in such a manner that a value of an Id stator current following deactivation of the synchronous motor has a predefined positive value and is higher than the Id stator current prior to deactivation.