A dehumidifier includes: a housing; a refrigerant circuit configured to allow low GWP refrigerant to circulate therethrough, the refrigerant circuit including a compressor having a variable operating frequency, a condenser, a pressure reducing device, and an evaporator, which are provided in the housing, the low GWP refrigerant being flammable and having a value of GWP of 6 or less; a blowing fan, which is provided in the housing, and is configured to take in air in a room into the housing and cause the taken-in air to pass through the evaporator and the condenser before blowing out the air from the housing into the room; and a water storage tank, which is provided below the evaporator, and is configured to accumulate dew condensation water generated in the evaporator, a number of refrigerant paths passing through the evaporator being greater than a number of refrigerant paths passing through the condenser.

Systems and methods are used to control operation of a rotary compressor of a refrigeration system to limit or prevent movement of rotors due to axial thrust loading resulting from rapid changes in speed of the rotors of the compressor. The operational profile of the motor is controlled to maintain acceleration torque and deceleration torque within predefined limits. The acceleration torque and deceleration torque are maintained within the predefined limits by controlling the speed of the motor, or by controlling the torque applied by the motor to the rotors during acceleration or deceleration.

A regulation method for an inverter compressor in a refrigeration system including establishing a working area via limit values for evaporation temperatures, condensation temperatures, compressor speeds, maximum compression ratio, and maximum reheat value, and measuring working values of the compressor in terms of evaporation temperature, condensation temperature, and compression ratio. If the compressor operates outside the established working area, the method includes modifying the working parameters of the compressor by acting on elements to be selected among the compressor speed, the opening angle of the expansion valve, and a combination thereof. If the compressor does not go back to the working area within a certain time, the method includes stopping operation of the compressor and triggering an alarm.

A power converter includes a transformation circuit configured to transform a rectified voltage, and a converter control unit configured to control a switching element of the transformation circuit. The converter control unit calculates a current command value based on a line voltage or the phase voltage, calculates a current deviation between the current command value and the reactor current, and calculates a switching command value from the current deviation. The converter control unit includes a plurality of integrators for the respective different phase angles of a power supply voltage. The integrator corresponding to a power supply phase angle is caused to accumulate the current deviation, and the integrator corresponding to a phase angle that is advanced by a set delay phase from the power supply phase angle is caused to output the control amount. A switching signal is generated with use of the control amount and the switching command value.

A variable speed drive comprises a voltage filter and voltage polarity protection unit including 1) a voltage filter circuit configured for low-pass filtering a voltage of an associated DC voltage source, and 2) a voltage polarity protection circuit configured to prevent incorrect polarity parring between the variable speed drive and the associated DC voltage source; a DC power supply unit being operatively connected to the voltage filter and voltage polarity protection unit via at least a positive polarity connection; an inverter unit being operatively connected to the DC power supply unit, a controllable load dump inserted in series with the positive polarity connection between the voltage filter and voltage polarity protection unit and the DC power supply unit, and a control unit configured to control at least the DC power supply unit, the inverter unit and the controllable load dump.

A refrigeration cycle device includes: a refrigeration cycle circuit including: a compressor and an indoor heat exchanger; an indoor air-sending device including a fan and a motor to supply air to the indoor heat exchanger; and a controller to control the frequency of the compressor and the rotation speed of the motor. The controller controls the rotation speed of the motor by controlling a frequency of an alternating current output from an inverter to the motor. The inverter is disposed at a position exposed to air heat-exchanged in the indoor heat exchanger. The controller controls the frequency of the compressor to a frequency at which a temperature of the inverter becomes lower than a first prescribed temperature in a state where the rotation speed of the motor is lower than a prescribed rotation speed.

An air-conditioning apparatus includes an indoor unit and an outdoor unit including a compressor that compresses a refrigerant and a motor drive system that drives the compressor. The motor drive system includes an inverter that converts a DC voltage into an AC voltage, and an electric motor including three stator windings with both ends open. The electric motor operates based on the AC voltage obtained by the inverter. The motor drive system further includes a connection state switching unit that has a function to change the connection state of the three stator windings included in the electric motor, and sets the connection state to a star connection at the start of operation of the air-conditioning apparatus.

A discharge device includes a capacitor, first and second discharge circuits each connected in parallel to the capacitor, and a comparator. The first discharge circuit includes a first discharge resistor. The second discharge circuit includes: a second discharge resistor smaller in resistance value than the first discharge resistor; and a switch connected in series to the second discharge resistor. The comparator turns off the switch when a voltage (VH) between power lines is equal to or higher than a prescribed voltage, and turns on the switch when the voltage becomes lower than the prescribed voltage. The comparator is configured to turn off the switch after an elapse of a prescribed time period since turning on of the switch.

Method for optimizing the energy consumption of a refrigeration unit, comprising: a step A: activating a driving device (14) of the compressor (13) by modulating the operating voltage Vout of the compressor (13) to an optimized value designed to activate the compressor (13) at an optimized speed determined by a thermodynamic optimization algorithm; a step B: regulating the driving device (14) which drives the AC/DC converter (17) so that the bus voltage is equal to the greater between a first threshold and a second threshold; wherein the first threshold is equal to the product of ?2 by the value of the supply voltage and the second threshold is equal to the product of ?2 by the value of the driving voltage; a step C: modifying the speed of each fan in order to minimize the value of an overall electrical consumption.

A control method and control system of a refrigerator with an inverter compressor. The control method includes: calculating the total cooling amount needed by a compartment to be cooled within a unit time; taking the total cooling amount as a first power of the inverter compressor and calculating a first frequency of the inverter compressor operating at the first power; and controlling the inverter compressor to operate at the first frequency. The present invention effectively controls the power consumption amount while satisfying the refrigerator cooling condition by calculating the total cooling amount needed by a refrigerator compartment within a unit time and adjusting the frequency of the inverter compressor.