The present disclosure relates to a cooling apparatus (1) comprising a metal and/or electrically conductive EMC enclosure (2) and a converter (E.sub.1) and also a plurality of electrically operated units (E.sub.2, . . . , E.sub.n) within the EMC enclosure (2) which are designed to influence a local temperature in at least one region (30, 31) inside or outside the EMC enclosure (2), wherein the converter (E.sub.1) directly supplies at least one or more of the units (E.sub.2, . . . , E.sub.n) with a respective supply voltage, and wherein the converter (E.sub.1) and the units (E.sub.2, . . . , E.sub.n) are each designed such that the line-bound and/or field-bound interference (S.sub.xy) which is specifically generated by this unit during operation of the cooling apparatus (1) is compensated for by a line-bound and/or field-bound interference (S.sub.xy) of at least one of the respectively other units (E.sub.1, . . . , E.sub.n) partially or completely in terms of its respective interference level (P.sub.n).

Inverter for an electric compressor comprising an auxiliary voltage supply that supplies a control electronics of the inverter with a DC voltage. The auxiliary voltage supply comprises a series circuit of a linear voltage regulator and a linear pre-regulator. The linear pre-regulator comprises a transistor and is connected to the input terminal of the linear voltage regulator. The linear pre-regulator and/or the linear voltage regulator are advantageously actively cooled by a refrigerant utilized in the electric compressor.

Compressors in a refrigerant loop are driven by variable frequency drives. The variable frequency drives are configured to demand current from an alternating current power source at different phases relative to one another such that at least one current harmonic frequency at the alternating current power source is cancelled.

An air conditioner includes a signal receiving unit to receive an operation instruction signal, a compressor including a motor including coils, an inverter connected to the coils, a connection switching unit to switch a connection state of the coils between a first connection state and a second connection state, and a controller to control the inverter and the connection switching unit. When the signal receiving unit receives an operation stop signal, the connection switching unit switches the connection state of the coils from the first connection state to the second connection state.

A free cooling outdoor unit includes: a refrigerant circuit through which refrigerant circulates; a brine circuit through which brine circulates; a water circuit through which water circulates; a fan configured to send air to the second heat exchanger; a flow control valve configured to control a circulation amount of the brine in the brine circuit; a water temperature detection sensor configured to detect a water temperature in the water circuit; an outside air temperature sensor; and a controller configured to control, where the outside air temperature is equal to or lower than a freezing temperature of the brine, the circulation amount of the brine based on the water temperature such that a brine temperature is prevented from reaching a temperature equal to or lower than the freezing temperature of the brine.

In order to restrain damage of a component due to rush current, a main relay in a power source circuit is not turned on and does not conduct a power source line even when a heat source microcomputer is activated with a capacitor not sufficiently charged. This configuration avoids start of charging the capacitor without current limitation, to restrain damage of the component due to rush current.

There are provided a booster to boost a voltage from a power supply, the booster including multiple stages connected in parallel; and a smoothing device to smooth the boosted voltage. Each of the multiple stages includes: an energy storage to receive current from the power supply and store energy; a switch to switch between connection and disconnection of a path for short-circuiting current from the energy storage; and a backflow preventer to prevent backflow from the smoothing device. At least one of the multiple stages is provided with a characteristic adjuster for adjusting switching characteristics of the switch.

A power converting apparatus includes: a rectifying unit configured to rectify an input AC power, a buck converter that is configured to step down a voltage of the rectified power and that is configured to output DC power having the step down voltage, a first inverter that is connected to an output terminal of the buck converter and that is configured to convert the DC power into AC power to drive a first motor, a second inverter that is connected to the output terminal of the buck converter, that is disposed in parallel to the first inverter, and that is configured to convert the DC power into AC power to drive a second motor, and a converter controller configured to control an output voltage of the DC power of the buck converter.

A refrigeration cycle including at least one outdoor unit including a plurality of compressors and indoor units each placed in indoor spaces comprises a plurality of compressors for supplying refrigerant to indoor units; and a controller for controlling cooperatively a plurality of the compressors in the outdoor unit to provide a capacity for air-conditioning in the indoor spaces through the indoor units, wherein the controller controls operation of the compressors so as to minimize a cost including start/stop of each compressor by prediction of an air-conditioning requirement in a next time chunk.

Embodiments of the present invention provide a method for controlling compressor braking, a frequency converter and a variable speed compressor. The method includes steps of: determining to brake a compressor, wherein a brake circuit includes three switching units and the three switching units are respectively electrically connected to three phases of windings of a motor of the compressor; actuating two of the three switching units to short-circuit two phases of windings of the motor. The two phases of windings of the motor are short-circuited by controlling the three switching units to generate braking torque, such that the compressor is braked without introducing a DC voltage, and thus the braking energy consumption is reduced. Besides, by turning on only two switches at a time, the switching abrasion is reduced, and the overall service life of the three switching units is effectively improved.