A rotary-machine control device includes: a connection switching device switching a connection state of stator windings of a rotary machine; a current detection unit detecting a rotary machine current flowing in the rotary machine; a voltage application unit applying voltage to the rotary machine; a control unit generating a voltage command provided to the voltage application unit and outputting a switching command to switch the connection state to the connection switching device; and an open-phase determination unit determining presence or absence of disconnection in the rotary machine or presence or absence of disconnection of a power distribution line to the rotary machine. During rotation of the rotary machine, the control unit outputs the switching command and the open-phase determination unit determines presence or absence of disconnection.

A motor drive apparatus includes a power converter including an inverter having an upper arm and a lower arm, the inverter being configured to control an operation of an electric motor, and a drive controller configured to apply a dead time for preventing a short circuit between the upper arm and the lower arm, and to control the power converter. The drive controller is configured to control the power converter by switching a first mode in which a first correction value representing a time used to correct a voltage drop due to the dead time is employed to control the power converter, and a second mode in which a second correction value smaller than the first correction value is employed to control the power converter.

According to one embodiment, a refrigeration cycle apparatus includes a motor which including a plurality of phase windings in a mutually unconnected state, a first inverter which controls application of electric power to one ends of the phase windings, a second inverter which controls application of electric power to the other ends of the phase windings, switches connected between the other ends of the phase windings, and a motor controller which selectively sets one of an open-windings mode and a star-connection mode. The motor controller sets, at the time of startup of the motor, the open-windings mode.

A monitoring and/or control device for an environmental control unit such as a heat pump determines the performance status and whether maintenance is required of a component of the unit for example a compressor during operation of the component. The device includes sensors configured to be situated relative to the compressor so as to receive and signal data from the compressor during operation of the component. In some embodiments, the device includes a vibration detector and a controller coupled to the vibration detector. The controller is configured to (i) receive electrical signals from the vibration detector, (ii) compare the electrical signals to a reference signal, (iii) determine the performance characteristic of the component based on the results of the comparison, and (iv) output a signal corresponding to the performance characteristic of the component to a user display. The controller may also request maintenance and/or order parts automatically.

According to one embodiment, a motor drive unit includes a motor including a plurality of phase windings in a mutually unconnected state, a first inverter which controls application of electric power to one ends of the phase windings, a second inverter which controls application of electric power to the other ends of the phase windings, relays each of which includes a make break contact connected between the other ends of the phase windings, and a controller which switches, according to a value of a current flowing through the motor, between an open-windings mode and a star-connection mode.

An air conditioner unit includes a variable speed compressor for circulating refrigerant through refrigeration loop and a controller configured to initiate an operating cycle, start a compressor transition timer, and determine an unfiltered compressor speed. The unfiltered compressor speed is fixed based on the selected operating mode until the compressor transition timer reaches a predetermined transition delay time, after which the unfiltered compressor speed is determined using a closed loop feedback control algorithm. The controller is further configured to operate the variable speed compressor at a target compressor speed that is modified from the unfiltered compressor speed based on the identification of a speed modification condition, such as a dehumidification deficiency, a speed restriction, or the identification of one or more resonance avoidance zones.

A control method for a refrigerator includes sensing a temperature of a storage room; operating a cool air supply at a cooling power when the sensed temperature of the storage room is equal to or above a first reference temperature; operating the cool air supply at a delay power, which is less than the cooling power, when the sensed temperature of the storage room is equal to or below a second reference temperature, which is less than the first reference temperature while the cool air supply is operating at the cooling power; and adjusting the cooling power or the delay power of the cool air supply according to the temperature of the storage room while the cool air supply is operating at the delay power, and operating the cool air supply at the determined adjusted cooling power or delay power.

An air conditioning system includes a compressor including a motor, a condenser, and an evaporator; a drive including an inverter providing a multiphase, AC output voltage to the motor; a current sensor configured to sense an output current generated by the inverter; a controller configured to communicate with the current sensor and the inverter, the controller configured to provide a voltage command to the inverter, the controller configured to execute operations including: monitor the output current generated by the inverter; compare the output current to a threshold; determine the occurrence of an over current condition when the output current exceeds the threshold; when an over current condition is detected, reducing the voltage command to the inverter.

Air conditioner units and methods of operating the same are provided. A method of operating an air conditioner unit includes determining a fan speed as a function of a compressor speed of a variable speed compressor of the air conditioner unit. The method also includes activating a variable speed fan of the air conditioner unit at the fan speed. An air conditioner unit may include a controller, and the controller may be configured for performing the method.

A system includes a pressure exchanger (PX). The PX is coupled to a motor that controls an operating speed of the PX. The system further includes a first pressure gauge configured to generate first pressure data indicative of a pressure of a fluid of a condenser. A first controller is to generate a first control signal based on the first pressure data. The motor of the PX is configured to adjust the operating speed of the PX based on the first control signal. The system further includes a pump. The system further includes a fluid density sensor for generating fluid density data associated with a first output fluid of the PX. A second controller is to generate a second control signal based on at least the fluid density data. The pump is to adjust an operating speed of the pump based on the second control signal.