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.

A method of operating a heating, ventilation, and air conditioning (HVAC) system including: transmitting, using an equipment control board, an operation request in a pulse width modulation (PWM) signal to an electronically commutate motor (ECM) controller of a blower motor, wherein the operation request includes a switching period command configured to vary a switching period of the PWM signal; operating the blower motor in accordance with the operation request by varying the switching period of the PWM signal; detecting a parameter of the blower motor for each of a plurality of switching periods as the switching period varies; and mapping the parameter of the blower motor for each of the plurality of switching periods.

Provided are a heat sink capable of suppressing overcooling of an electronic component which should not be overcooled and highly efficiently cooling only an electronic component which should be cooled, and a circuit device including the same. A heat sink includes a pipe and a cooling block. At least one projection is formed in the cooling block. The pipe is in contact with the projection. The pipe is arranged with a spacing from a portion of the cooling block other than the projection.

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.

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.

A controller for a compressor, more specifically for a first electrical VSD motor configured to drive a compressor element, the controller including a housing in which is provided a rectifier, a DC link with a DC bus and two inverters connected to the same DC bus, a first inverter configured to control the first VSD motor driving the compressor element, and a second inverter configured to control a second VSD motor driving a fan configured to cool the compressor.

A heating, ventilation, and/or air conditioning (HVAC) system includes a compressor having an impeller configured to rotate and drive a working fluid through a working fluid circuit of the HVAC system in an active operating mode. The HVAC system further includes a controller configured to, in response to receiving an input indicative of a transition to operate in an inactive operating mode, suspend the active operating mode by interrupting a supply of power to the compressor, adjust pre-rotation vanes of the compressor, a variable geometry diffuser of the compressor to a first position, or both to enable a backflow of the working fluid through the compressor for a first interval of time, and, after the first interval of time has elapsed, adjust the pre-rotation vanes, the variable geometry diffuser, or both to a second position to block the backflow of the working fluid through the compressor.

Included are: a compressor including a compression mechanism that compresses refrigerant, and a motor that drives the compression mechanism; an inverter that applies desired voltage to the motor; an inverter controller that controls the inverter; a high-pressure switch that operates when a discharge pressure of the compressor becomes a preset pressure or higher; and a thermal protector that operates when the temperature of the compressor becomes a preset temperature or higher, wherein the high-pressure switch and the thermal protector are installed on a power supply line for supplying power to the inverter, and the high-pressure switch is opened when the discharge pressure of the compressor becomes the preset pressure or higher, or the thermal protector is opened when the temperature of the compressor becomes the preset temperature or higher, to interrupt power supply to the inverter.

An air conditioning apparatus includes an indoor unit and an outdoor unit. The outdoor unit includes a compressor that compresses a refrigerant and a motor drive apparatus that drives the compressor. The motor drive apparatus includes an inverter that converts a direct-current voltage into an alternating-current voltage and a motor that operates on the alternating-current voltage from the inverter. The motor includes six stator windings that are each openable at both ends. The motor drive apparatus further includes a connection state switching unit that includes a function of switching a connection state of the six stator windings of the motor among at least four types of connection states.

Provided is a controller, an air conditioner, and a high-pressure protection circuit. The controller includes a first rectifier unit, a power conversion unit, a high pressure switch (HPS) wiring terminal, a low-voltage control unit, and a high-voltage operating unit. An input end of the first rectifier unit is capable of being electrically connected to an input power supply. An output end of the first rectifier unit is electrically connected to an input end of the power conversion unit. An output end of the power conversion unit is electrically connected to a power supply end of the low-voltage control unit. The HPS wiring terminal is connected to the front end of the power supply end of the low-voltage control. The controller has a function of high-pressure protection.