A compressor driving device includes: a controller (23) that PWM drives a compressor; an inverter circuit unit (4) that supplies power to an electric motor included in the compressor; a drive circuit (5) that drives the inverter circuit unit (4) according to a control signal; a voltage detector (9) that detects a voltage that is output to the electric motor; and a current detector (10) that detects a current that is output to the electric motor. When a product of a detection value of the voltage detector (9) and a detection value of the current detector (10) is greater than a predetermined comparison value, a duty ratio of the control signal is reduced to cause the input power supplied to the electric motor by the inverter circuit unit (4) to have a predetermined input power level or less.

A refrigeration device includes a blow-out temperature detector that detects the blow-out temperature of air blown out into the interior of the device, a cargo temperature detector that detects the temperature of a cargo, an operation controller that performs cooling control of the interior on the basis of the detection temperature from the blow-out temperature detector and the detection temperature from the cargo temperature detector, a storage unit that stores a first set temperature as a control target value for the blow-out temperature and a cargo target temperature as a target value for the temperature of the cargo, and a time measurement unit that measures a treatment time elapsed for low-temperature treatment of the cargo. The operation controller is configured to control the refrigerant circuit so that the blow-out temperature approaches the first set temperature. The time measurement unit is configured to start measuring the treatment time when the temperature of the cargo is lower than the cargo target temperature.

An adder adds a phase plus, which is n times a size of 60 degrees, to a phase output from a phase switching unit and outputs the phase as a voltage command phase . A voltage generation unit generates voltage command value based on the voltage command phase output by the adder and outputs the command value. A drive-signal generation unit, based on an output from the voltage generation unit generates drive signals corresponding to respective switching elements of an inverter, and outputs respective generated drive signals to the corresponding switching elements of the inverter, and generates a high-frequency AC voltage in the inverter.

An engine driven heat pump is such that when a self-sustaining switch is turned on during power failure, and a self-sustaining signal is received, it switches to a self-sustaining mode and start an engine and a generator, and when output power from an inverter is received, it supplies the output power to a power supply circuit and a battery charging circuit by means of an independent power supply relay, and it supplies the output power to the outside via an independent output unit, and during the supply of the output power, it maintains cutoff with respect to connection between a system, and the power supply circuit and the battery charging circuit by means of a system cutoff relay and maintain the output of the output power until the self-sustaining signal is interrupted, and it recovers the connection when power is restored and the output power is interrupted.

The power conversion device includes a power-supply shunt resistance provided between an inverter and the negative-voltage side of a DC power supply, respective-phase lower-arm shunt resistances provided between the power-supply shunt resistance and respective-phase lower-arm switching elements, a first overcurrent detection unit performing overcurrent detection on a current that flows through the power-supply shunt resistance on the basis of a power-supply shunt-resistance voltage, and a second overcurrent detection unit performing overcurrent detection on each current that flows through the respective-phase lower-arm shunt resistances on the basis of respective-phase lower-arm voltages, wherein overcurrent detection is performed on each phase current using either one of the overcurrent detection result of the first overcurrent detection unit and the overcurrent detection result of the second overcurrent detection unit.

The refrigerant discharged from a compressor is distributed based on the priorities set by the user in advance and the remaining refrigerant is further distributed based on the priorities. Thus, setting the priorities for indoor units according, for example, to the usage of work spaces and the like in an office building, the user can operate a heat pump system efficiently in accordance with the intended use. Furthermore, the remaining capacity of the outdoor unit is distribute to the remaining indoor units according to their priorities so that the indoor units are operated efficiently within the range of the cooling capacity of the outdoor unit.

A cooling structure for electronic components includes: a case having a refrigerant intake port and a refrigerant channel through which a refrigerant introduced from the refrigerant intake port flows, the refrigerant channel being formed by a wall section; a cooling section having a plurality of flat surfaces formed inside of the case in a manner to interpose the wall section between the flat surfaces and the refrigerant channel; and a plurality of electronic components arranged inside of the case and each of which is in contact with one of the flat surfaces. Each of the electronic components is cooled by the refrigerant via a corresponding flat surface of the flat surfaces and the wall section.

A point to point, point to multipoint, or multipoint to multipoint integrated inverter compressor variable volume refrigerant loop data center cooling unit and control system used to regulate volume of refrigerant to air handling systems used to supply cold air ventilation to data center rooms and to the electronic equipment mounted therein which require constant cooling by using a control system controlling variable speed pumps, fans, compressors and condensers to operate a one or a plurality of closed loop, variable volume refrigerant loop systems in conjunction with one or a plurality of associated interior air handling systems located within a data center.

A method of operating an electric motor is disclosed. The method includes: starting the electric motor in an open loop control mode; operating an estimator that estimates operating conditions of the electric motor; and, while the electric motor is in the open loop control mode, evaluating a first parameter of the estimator. The method further includes: in response to the evaluation of the first parameter, determining whether the estimator has converged; and in response to a determination that the estimator has not converged within a predetermined period of time after starting the electric motor, signaling a first fault condition.

A variable speed drive (VSD) can be used to vary the voltage-to-frequency ratio (V/f) supplied to a compressor motor of a heating, ventilation, air conditioning or refrigeration (HVAC&R) system to compensate for varying conditions in the HVAC&R system.