An electric-motor driving apparatus according to the present invention is the electric-motor driving apparatus that drives an electric motor having a winding structure in which a first multi-phase winding and a second multi-phase winding are wound and includes a first DC/AC converter connected to the first multi-phase winding and applying a multi-phase alternating-current voltage to the electric motor, a second DC/AC converter connected to the second multi-phase winding and applying a multi-phase alternating-current voltage to the electric motor, a first three-phase switching unit to perform connecting and disconnecting between phases of the first multi-phase winding, a second three-phase switching unit to perform connecting and disconnecting between phases of the second multi-phase winding, and a winding switching unit to perform connecting and disconnecting between the first multi-phase winding and the second multi-phase winding.

A compressor driving apparatus and an air conditioner including the same, whereby the compressor driving apparatus includes a capacitor connected to a DC terminal, an inverter, including a plurality of three-phase switching devices, to convert DC power from the capacitor into AC power to drive a compressor motor, an output current detector to detect output current flowing in the motor, and a controller to output a switching control signal for controlling the inverter based on the output current, wherein the controller performs control such that some of the three-phase switching devices in the inverter are turned on or off in a compressor preheating mode.

A power converter includes: a power conversion module configured to convert a voltage and a frequency of power that is supplied from a power supply through a power wire, and to supply to a load, power having a voltage and a frequency that are obtained by conversion; and an active noise canceller configured to detect noise that flows through the power wire, and to output a noise canceling signal that attenuates the noise to the power wire. The active noise canceller includes a first substrate on which a strong electric circuit configured to detect the noise is mounted, and a second substrate on which a light electric circuit configured to produce the noise canceling signal is mounted.

A hermetic compressor (100) includes an electric element (110), a compression element (112), and a hermetic container (102). The compression element includes a shaft (118), a cylinder block (124), a piston (136), a connection section (144), and an oil supply mechanism (130). The piston has a columnar seal section (160) in sliding contact with an inner peripheral face of the cylinder, two extension sections (162) that have circular arc faces each having the same radius as a radius of the seal section and extend from the seal section to the bottom dead center side in the axial direction with a circumferential gap therebetween, and a columnar capture section (164) that extends further toward the bottom dead center side than the extension section and has a smaller radius than the radius of the seal section.

A refrigerating and air-conditioning system includes a plurality of independent refrigerating and air-conditioning apparatuses each including a refrigerant circuit and a defrosting unit, and further includes a system controller managing the apparatuses in an integrative manner. The system controller includes a defrosting operation control unit. When a time interval between an estimated defrosting start time calculated for a given refrigerating and air-conditioning apparatus and a subsequent estimated defrosting start time calculated for another refrigerating and air-conditioning apparatus is less than or equal to a predetermined target start time interval, the defrosting operation control unit transmits a defrosting start instruction signal to the defrosting unit of the given refrigerating and air-conditioning apparatus.

Provided is a refrigeration apparatus capable of, even in occurrence of a refrigerant leak, suppressing the extent of the refrigerant leak in continuously operating a usage unit other than a usage unit at which the refrigerant leak occurs. When one of a first usage unit and a second usage unit connected in parallel via a liquid-refrigerant connection pipe and a gas-refrigerant connection pipe is in a refrigerant leak situation satisfying a predetermined condition, a controller closes an on-off valve of a leak unit, the on-off valve being disposed on the side of the liquid-refrigerant connection pipe with respect to a usage-side heat exchanger, continues to open an on-off valve of a non-leak unit, the on-off valve being disposed on the side of the liquid-refrigerant connection pipe with respect to a usage-side heat exchanger, and reduces a refrigerant pressure at a portion on the side of the liquid-refrigerant connection pipe with respect to each on-off valve below a refrigerant pressure at the portion at a time when the refrigerant leak situation satisfies the predetermined condition.

A chiller system includes a compressor, a condenser and an evaporator in fluid communication. A motor drives the compressor. A variable speed drive powers the motor. An oil heater and pump system circulate heated lubricating oil in the compressor. A control panel is arranged to determine whether an input parameter is greater than or equal to a threshold parameter; deactivate the VSD in response to sensing that the input parameter is less than the threshold parameter; determine at least one chiller capacity control parameter at a point when the VSD is deactivated, and maintain the at least one chiller capacity control parameter while the VSD is deactivated; determine that the input parameter has been restored; determine a motor rotation and motor rotational speed; and in response to determining that the input parameter is restored and the motor is rotating in a forward direction, reactivate the VSD.

A drive includes an inverter power circuit that applies power to an electric motor of a compressor from a direct current (DC) voltage bus. A power factor correction (PFC) circuit outputs power to the DC voltage bus based on input alternating current (AC) power. The PFC circuit includes: (i) a switch having a first terminal, a second terminal, and a control terminal; (ii) a driver that switches the switch between open and closed states based on a control signal; (iii) an inductor that charges and discharges based on switching of the switch; and (iv) a circuit that outputs a signal indicating whether the switch is in the open state or the closed state based on a voltage across the first and second terminals of the switch.

Systems and methods are provided and include a variable-capacity compressor operable in a first capacity mode and in a second capacity mode that is higher than the first capacity mode. A control module is configured to switch the variable-capacity compressor between the first capacity mode and the second capacity mode based on a demand signal from a thermostat and an indoor relative humidity sensed by an indoor relative humidity sensor. The control module determines whether the indoor relative humidity is greater than a predetermined humidity and operates the variable-capacity compressor in the second capacity mode in response to receiving the demand signal from the thermostat and the indoor relative humidity exceeding the predetermined humidity.

A PFC circuit is provided. A bridge rectification circuit receives an AC voltage and generates a rectified AC voltage. A power converter converts the rectified AC voltage to a first DC voltage, where the power converter includes a switch and supplies the first DC voltage to a DC bus to power a compressor. A current sensor detects an amount of current. A control module, while operating in a correction mode: based on the rectified AC voltage, a phase angle of the rectified AC voltage, a second DC voltage of the DC bus, or the detected amount of current, control operation of the switch to transition between operating in a high activity mode and an inactive or low activity mode; transition the switch between open and closed states while in the high and low activity modes; and maintain the power converter in an OFF state while in the inactive mode.