A heat pump apparatus includes: a compressor including a motor; an inverter that applies a desired voltage to the motor; a current detector that detects current flowing to the motor; a drive-signal generation unit that generates a drive signal for the inverter; a magnetic-pole position estimation unit that changes a voltage phase of a voltage command value for a high-frequency voltage, and estimates a maximum-heat-amount acquisition magnetic-pole position when the generation unit applies the high-frequency voltage to the motor to heat the compressor; a steady heating control unit that determines an amplitude and voltage phase of the voltage command value from the maximum-heat-amount acquisition magnetic-pole position and a defined necessary amount of heat when the generation unit applies the high-frequency voltage to the motor to heat the compressor; and a control switching determination unit that causes one of the estimation unit and the heating control unit to operate.

The present application concerns a climate control unit for controlling air temperature and/or humidity. Moreover, the present application concerns a system comprising such a climate control unit. The climate control unit according to the invention makes use of two refrigerant paths that share a common part in which a compressor and evaporator are arranged, and that each have a non-shared part. A reheat coil is provided in one of the non-shared parts. According to the invention, a respective expansion device is provided in both non-shared parts.

The present invention relates to a method for controlling a clothes treating apparatus, the method comprising: a circulation step of circulating air by operating a fan; a heat exchange step of opening a refrigerant pipe by controlling an expansion valve, and circulating a refrigerant by operating a compressor; a circulation termination step of terminating the operation of the fan when the dryness level of clothes stored in a receiving part reaches a predetermined reference dryness level or when the elapsed time of the heat exchange step reaches a predetermined reference time; and a return step of closing the refrigerant pipe by controlling the expansion valve, and returning the refrigerant and lubricant in the refrigerant pipe to the compressor by operating the compressor.

A vapor cycle compressor includes a motor section and a compression section operatively engaged with the motor section. A refrigerant path is in the motor section and in the compression section. The refrigerant path includes: a compression refrigerant path, for a single phase compression refrigerant, in the compression section; an inner rotor shaft refrigerant path, for a single phase inner rotor shaft refrigerant, in the compression section and in the motor section; and a stator refrigerant path, for a two phase stator refrigerant, in the motor section.

A domestic refrigeration device and a method for operating a domestic refrigeration device. The domestic refrigeration device has a heat-insulated body with a coolable inner container which delimits a coolable interior provided for storing food. A coolant circuit is provided for cooling the coolable interior and includes a compressor and a field-oriented electric drive. The field-oriented electric drive has a field-oriented controller, a converter, and a permanently excited synchronous motor which is connected downstream of the converter and which is part of the compressor or is provided for driving the compressor.

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.

A heat pump apparatus includes: a compression mechanism that compresses a refrigerant; a motor that drives the compression mechanism; an inverter that applies a voltage to the motor; and an inverter control unit that generates a drive signal for driving the inverter, based on a carrier signal, in which the inverter control unit periodically changes a carrier frequency of the carrier signal in a heating operation mode in which the refrigerant is heated, and generates the drive signal such that a period of time during which a voltage represented as a real vector is applied to the motor is kept constant regardless of the changed carrier frequency.

There is provided a starting method for a cryocooler, the cryocooler including a compressor, a cold head, a high pressure line, and a low pressure line, the method including increasing a volume of the high pressure line when the cold head is at a room temperature, cooling the cold head from the room temperature to a cryogenic temperature while controlling an operation frequency of the compressor based on a pressure of the high pressure line or a differential pressure between the high pressure line and the low pressure line, after the volume of the high pressure line has been increased, decreasing the volume of the high pressure line after the cold head has been cooled to the cryogenic temperature, and maintaining the cold head at the cryogenic temperature after the volume of the high pressure line has been decreased.

A system includes an electronic power converter and a controller. The electronic power converter supplies power to one or more motor drives of an HVAC system. The controller obtains a plurality of pulse width modulation (PWM) algorithms. Each PWM algorithm has an associated spectrum of frequencies. The controller further determines one or more resonance frequencies associated with the HVAC system. The controller also selects a first PWM algorithm from the plurality of PWM algorithms wherein the spectrum of frequencies of the first PWM algorithm lacks frequency peaks that overlap with the one or more resonance frequencies associated with the HVAC system. The controller further operates the electronic power converter according to the first PWM algorithm.

A compressor unit (2) for use in a refrigeration circuit, comprises at least two compressors (8, 10); and a common variable frequency drive (6), configured to be connected to a three phase grid voltage supply (4); each compressor (8, 10) having an inlet port (12) configured to be in refrigerant communication, via a suction line, with an outlet of an evaporator; an outlet port (14) configured to be in refrigerant communication, via a pressure line, to an inlet of a condenser; a compressor motor (18), particularly an alternating current induction motor, with a three phase supply line (32-1, 32-2); a power modulation means (24) for controlling the power of the compressor (8, 10) according to its load needs; wherein each compressor (8, 10) is switchable, independently from the respective other compressor(s) (8, 10), to be connected, during start-up and acceleration of the respective compressor (8, 10), to the common variable frequency drive (6), and to be connected, during rated-speed operation of the respective compressor (8, 10), to a common three phase grid voltage supply (4).