An energy efficient heat pump for a heating, ventilation, and air conditioning (HVAC) system includes a vapor compression circuit, a heat exchanger of the vapor compression circuit configured to place a working fluid in a heat exchange relationship with an air flow directed across the heat exchanger, and a conduit system of the vapor compression circuit. The conduit system of the vapor compression circuit is configured to direct the working fluid into the heat exchanger and to receive the working fluid from the heat exchanger, wherein the conduit system is configured to direct the working fluid into the heat exchanger to place the working fluid in a counterflow arrangement with the air flow directed across the heat exchanger in a cooling mode of the heat pump and in a heating mode of the heat pump.

A sensor for detecting contamination of a cryogenic refrigerant in a cryogenic refrigeration system, a method and a refrigeration system are disclosed. The sensor comprises: an inlet for coupling to a cryogenic refrigerant flow path in the cryogenic refrigeration system and a thermal conductivity detector in fluid communication with the inlet. The thermal conductivity detector is configured to generate a signal indicative of a detected thermal conductivity of the cryogenic refrigerant received from the cryogenic refrigeration system when the sensor is coupled thereto. The sensor also comprises circuitry configured to convert the thermal conductivity signal to an indication of contamination of the cryogenic refrigerant; and an output configured to output the indication of contamination of the cryogenic refrigerant.

An energy allocation system includes an air conditioning unit with a VDC compressor and a fan configured for variable speed output. The air conditioning unit further includes a built-in power generator. A blending module is configured to split the generator-produced power into AC and DC allocations and combine the DC power allocation with DC power received from a DC energy device.

An energy allocation system includes an air conditioning unit with a VDC compressor a generator, and a voltage converter. The air conditioning unit is configured to receive DC power from a DC energy device. A blending module is executable by a processor to cause AC power produced by the generator to be split into AC and DC power allocations using the converter and cause AC power received from a local electric utility grid to be converted to DC power.

An electric motor drive device including a drive controller configured to control an operation of an inverter, the drive controller including a frequency setting unit configured to set an operating frequency of an electric motor, a frequency determining unit configured to determine whether or not the operating frequency set in the frequency setting unit is equal to or lower than a set frequency threshold value, a voltage determining unit configured to determine whether or not a value of a DC voltage is equal to or larger than a set voltage threshold value, and an inverter controller configured to control the inverter based on the operating frequency set in the frequency setting unit.

An inverter unit (100) includes an inverter (110), an inverter housing (120) and an insulating member (130). The inverter (110) drives an electric motor (200) and includes at least one power module (112) for converting a High Voltage (HV) Direct Current (DC) to a three-phase Alternating Current (AC) that drives the electric motor (200). The inverter housing (120) receives the inverter (110). The power module (112) is mounted on an end wall (120a) of the inverter housing (120) by means of bolts (114). The insulating member (130) corresponding to each bolt (114) is disposed between a head portion (114a) of the corresponding bolt (114) and the power module (112).

A PFC circuit is provided. A first bridge rectifier receives an AC voltage. A power converter includes a switch and receives an output of the first bridge rectifier, converts the output to a first DC voltage, and supplies the first DC voltage to a DC bus to power a compressor. A second bridge rectifier receives the AC voltage and bypasses at least one of the first bridge rectifier, a choke and a diode of the PFC circuit to provide a rectified AC voltage out of the second bridge rectifier to the DC bus to power the compressor. A control module controls operation of a driver to transition the switch between open and closed states to adjust a second DC voltage on the DC bus, where the second DC voltage, depending on the AC and second DC voltages, is based on the first DC voltage or the rectified AC voltage.

A drive includes: an inverter power circuit that applies power to an electric motor of a compressor from a direct current (DC) voltage bus; and a power factor correction (PFC) circuit that outputs power to the DC voltage bus based on input alternating current (AC) power. The PFC circuit includes: (i) a switch; (ii) a driver that connects a control terminal of the switch to a first reference potential when a control signal is in a first state and that connects the control terminal of the switch to a second reference potential when the control signal is in a second state; and (iii) an inductor that charges and discharges based on switching of the switch. The drive also includes a control module that generates the control signal based on a measured current through the inductor and a predetermined current through the inductor.

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.

Systems and methods for providing power to a refrigeration unit or an air conditioner used on a hybrid vehicle. The system includes an accumulation choke, a PWM rectifier, and a frequency inverter. The accumulation choke is configured to receive a first AC power, a second AC power, and a DC power. The accumulation choke and PWM rectifier convert the received power into an intermediate DC power having a peak voltage. The PWM rectifier provides the intermediate DC power to the frequency inverter. The frequency inverter converts the intermediate DC power to an output AC power. The frequency inverter provides the output AC power to the refrigeration unit.