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.

The present invention relates to a method for simultaneous operation of a plurality of chopper circuits of a wind turbine power converter, the method comprising the steps of operating a controllable switching member of a first chopper circuit in accordance with a first switching pattern, and operating a controllable switching member of a second chopper circuit in accordance with a second switching pattern, wherein the first switching pattern is different from the second switching pattern during a first time period. In order to reduce switching losses the first switching pattern may involve that the controllable switching member of the first chopper circuit is clamped during the first time period. Additional chopper circuits may be provided in parallel to the first and second chopper circuits. The present invention further relates to a power dissipation chopper being operated in accordance with the before mentioned method.

A motor driving device includes: a converter that converts AC power into DC power; a DC link capacitor provided for the DC link; an inverter that converts DC power into AC power for a motor; an initial charging circuit that charges the DC link capacitor; a potential difference determination unit that determines a potential difference between both ends of the initial charging circuit; a direct current detecting unit that detects direct current supplied to the initial charging circuit; an alternating current detecting unit that detects alternating current supplied to a motor; and an abnormality determination unit that determines that abnormal heat generation occurs in the initial charging circuit when the alternating current detecting unit detects alternating current and the direct current detecting unit detects direct current, in a case in which a potential difference occurs between both of the ends of the initial charging circuit.

A motor control apparatus includes an AC-DC converter, an auxiliary power source, and an inverter. The AC-DC converter converts AC power into DC power and feeds the DC power to a DC bus bar. DC power is fed from the auxiliary power source to the DC bus bar and from the DC bus bar to the auxiliary power source. The inverter converts the DC power of the DC bus bar into the AC power and feeds the AC power to a motor. The auxiliary power source includes a capacitor, a DC-DC converter, and circuitry. The DC-DC converter performs conversion between a first DC voltage of the DC bus bar and a second DC voltage applied between both terminals of the capacitor or inside of the capacitor. The circuitry is configured to control the DC-DC converter to maintain positive correlation between the second DC voltage and the first DC voltage.

A device for driving a plurality of motors, including an inverter connected to a DC terminal; a multi-phase motor connected to the inverter; and a single-phase motor serially connected to the multi-phase motor, wherein a number of frequency of current input to the multi-phase motor when driving the single-phase motor and the multi-phase motor at the same speed is smaller than the number of frequency of current input to the multi-phase motor when driving the single-phase motor and the multi-phase motor at different speeds. Accordingly, a plurality of motors can be simultaneously driven at different speeds, by using a single inverter.

Disclosed is a drain pump driving apparatus and a laundry treatment machine including the same. The laundry treatment machine includes: a drain pump driving apparatus configured to drive a drain pump, wherein the drain pump driving apparatus includes: a motor to drive the drain pump; an inverter to convert a direct current (DC) power to an alternating current (AC) power by a switching operation, and output the converted AC power to the motor; an output current detector to detect an output current flowing to the motor; and a controller configured to control the inverter, wherein the controller is further configured to calculate a speed of the motor based on an output current, and calculate a lift, which is a difference between a water level of a water introduction part through which water flows into the drain pump and s water level of a water discharge part for discharging water from the drain pump, based on the calculated speed.

A current is supplied from a power source voltage supply node of a power source voltage to an open-collector of a transistor through a current blocking circuit, connectors and a signal transmission line. A microcomputer regulates a resistance value of a pull-up resistor by switching over an on/off state of a switch circuit in accordance with the power source voltage detected by a power source voltage detection circuit. The microcomputer thus regulates a current blocking rate of the current blocking circuit.

A motor drive of an embodiment of the present invention includes a PWM converter for converting AC power inputted from a low voltage AC power source into DC power by PWM control, an inverter for converting the received DC power to AC power to drive a motor, and a capacitor connected between the PWM converter and the inverter. The PWM converter is operated so as to limit input and output currents or input and output power to predetermined values, and supplied from the low voltage AC power source with a lower voltage than a voltage required to drive the motor. The PWM converter boosts a DC link voltage being an output voltage to the voltage able to drive the motor, and thereby serves to increase the potential difference of the capacitor between charged and discharged states to reduce the capacitance of the capacitor.

A motor drive apparatus includes: a rectifier; an inverter; a DC link voltage detection unit; an input current detection unit configured to detect input current inputted to the rectifier; a DC link voltage comparison unit configured to compare a DC link voltage with a first voltage threshold value and with a second voltage threshold value; a current comparison unit configured to compare the input current with a current threshold value; and an abnormality detection unit configured, in a case that the DC link voltage is smaller than the first voltage threshold value or that the DC link voltage is greater than the second voltage threshold value, to determine that a first abnormality has occurred when the input current is smaller than the current threshold value and to determine that a second abnormality has occurred when the input current is equal to or greater than the current threshold value.

Embodiments of the present disclosure provide a method for controlling a fan, a system, and an air conditioner. The method includes: turning off a first bridge arm group in an inverter of the fan; applying a preset driving signal to a second bridge arm group in the inverter; detecting an electrical signal of a stator of the fan after the preset driving signal is applied; determining an initial state of the fan according to the electrical signal of the stator of the fan, wherein the initial state of the fan includes a downwind forward state, a static start state, or an unwind reverse state; and providing the fan with a control signal matching the initial state of the fan according to the initial state of the fan.