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 method of operating an electric motor is disclosed. The method includes: determining a d-axis resistance of an electric motor and a Q-axis resistance of the electric motor as a function of a bulk current; determining a d-axis inductance of the electric motor and a Q-axis inductance of the electric motor as a function of the bulk current; generating an estimated flux of the electric motor based on the d-axis resistance of the electric motor, the Q-axis resistance of the electric motor, the d-axis inductance of the electric motor, and the Q-axis inductance of the electric motor; generating an estimated angle of the electric motor based on the estimated flux of the electric motor; and, based on the estimated angle of the electric motor, controlling switching of an inverter that powers the electric motor.

A compressor control device, a method for controlling a compressor, and a refrigerator including the same are provided. The compressor control device controls the compressor to be driven using a mode in which the compressor is selectively driven by an inverter and a mode in which the compressor is driven directly using a supply voltage, according to a quality of the supply voltage, a loss which is caused by use of the inverter reduced or removed by directly providing the supply voltage to the compressor within a predetermined voltage or frequency range, and an increased energy efficiency by reducing power consumption.

A control method for a solar air conditioner comprises: a detection step, starting to detect the change situation of a DC voltage output by an inverter in the solar air conditioner when it is detected that the solar air conditioner enters an energy-saving control mode; and a judging step, adjusting an operating frequency of a compressor of the solar air conditioner according to the change situation of the DC voltage, so that the solar air conditioner uses a solar cell to supply power. Thus, solar energy can be used to the maximum degree, the problem that there is a need to supply power by a mains power supply because the power supplied for the solar energy is insufficient is avoided, and the cost is saved. Further disclosed are a control device for a solar air conditioner and a solar air conditioner.

An air conditioner including: a converter circuit that is on an electronic substrate and converts an alternating current to a direct current; an inverter circuit that is on the electronic substrate and converts a direct current converted by the converter circuit to an alternating current to operate a motor that drives a compressor; an inverter control circuit that is on the electronic substrate and drives the inverter circuit; and a temperature detector that detects an outside air temperature input to the inverter control circuit, wherein the inverter control circuit includes a locked energization control unit, and the locked energization control unit performs AC locked energization or DC locked energization on the motor in accordance with the outside air temperature detected by the temperature detector.

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.

A variable refrigerant package air conditioner is shown that is easy to install in new construction with a unique base that causes collected mixture that overflows to drain outside the building. A control system is shown that has motors and compressor that are pulse width modulated so the air conditioner is infinitely variable while maintaining the highest possible power factor. Dehumidification of outside air occurs as it is mixed with inside air. By gradually approaching a temperature set point and even reheating after dehumidification, moisture is removed from the room.

An air-conditioning apparatus includes a compressor, an indoor heat exchanger configured to function as a condenser or an evaporator, indoor heat exchanges each configured to function as a condenser or an evaporator, a plurality of expansion valves each provided for a corresponding one of the indoor heat exchangers each configured to adjust a flow rate of a refrigerant that flows through the corresponding indoor heat exchanger, and a controller configured to control an operation capacity of the compressor and opening degrees of a plurality of expansion devices. When increasing heat exchange performance of the indoor heat exchanger, the controller increases the operation capacity of the compressor and controls the opening degree of the expansion valve corresponding to the indoor heat exchanger to decrease the flow rate of the refrigerant that flows through the indoor heat exchanger.

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 power conversion apparatus, including: an MLC circuit configured to boost an input voltage from a three-phase rectifier; a smoothing capacitor configured to smooth an output of the MLC circuit; an inverter control unit configured to generate a PWM signal; an inverter circuit configured to convert a DC voltage of the smoothing capacitor into an AC voltage based on an input of the PWM signal and to supply the AC voltage to a motor; a boost mode switching unit having at least three boost modes in which a boost level of the input voltage is selected and configured to switch among the at least three boost modes depending on an operation status of the motor determined for the purpose of controlling a refrigeration cycle; and an MLC control unit configured to control the MLC circuit based on the switching by the boost mode switching unit.