In a motor driving apparatus including a DC power supply circuit of variable output voltage value, an inverter of variable frequency, and a connection switching device for selecting connection, switching of the connection switching device is performed in a state where an output voltage of the DC power supply circuit is increased, a rotational speed of a motor is increased, and a current flowing through the motor is made not greater than a predetermined threshold. For example, the switching of the connection switching device is performed in a state where the current through the motor is made zero. For example, the switching is performed in a state where the output voltage of the DC power supply circuit is set at a value corresponding to the rotational speed of the motor during the switching. It is possible to prevent increase in apparatus size and switch the connection of windings while the motor is rotating.

An electric motor drive device includes: a main substrate mounted with a power supply circuit that generates, on the basis of alternating-current power supplied from an alternating-current power supply, a drive power to drive a compressor motor; a plurality of connection switching relays that perform switching between connections for the compressor motor; a small substrate mounted with the connection switching relays; a relay drive circuit that switches the connection switching relays; lead wires that connect the compressor motor and the small substrate to the power supply circuit; and lead wires that connect the small substrate and the compressor motor.

An electric motor drive device includes: a main substrate mounted with a power supply circuit that generates, on the basis of alternating-current power supplied from an alternating-current power supply, a drive power to drive a compressor motor; a plurality of connection switching relays that perform switching between connections for the compressor motor; a small substrate mounted with the connection switching relays; a relay drive circuit that switches the connection switching relays; lead wires that connect the compressor motor and the small substrate to the power supply circuit; and lead wires that connect the small substrate and the compressor motor.

Each of plural temperature adjustment apparatuses variably adjusts the amount of heat exchange between an inflow medium, which is a liquid medium supplied to a corresponding indoor heat exchanger, and an outflow medium, which is a liquid medium discharged from the corresponding indoor heat exchanger. Each of the plural temperature adjustment apparatuses reduces the heat exchanging capacity of the corresponding indoor heat exchanger by increasing the amount of heat exchange between the inflow medium and the outflow medium when the heat exchanging capacity of the corresponding indoor heat exchanger is larger than the indoor load. When there is no temperature adjustment apparatus in which the amount of heat exchange between the inflow medium and the outflow medium is set to the minimum, the heat source apparatus reduces the heating capacity or the cooling capacity for changing the temperature of the liquid medium.

Each of plural temperature adjustment apparatuses variably adjusts the amount of heat exchange between an inflow medium, which is a liquid medium supplied to a corresponding indoor heat exchanger, and an outflow medium, which is a liquid medium discharged from the corresponding indoor heat exchanger. Each of the plural temperature adjustment apparatuses reduces the heat exchanging capacity of the corresponding indoor heat exchanger by increasing the amount of heat exchange between the inflow medium and the outflow medium when the heat exchanging capacity of the corresponding indoor heat exchanger is larger than the indoor load. When there is no temperature adjustment apparatus in which the amount of heat exchange between the inflow medium and the outflow medium is set to the minimum, the heat source apparatus reduces the heating capacity or the cooling capacity for changing the temperature of the liquid medium.

System recognition is performed on devices connected to an identical system without recognizing a device of a different system as a device of the identical system in high-frequency communication. In a device network system, an outdoor unit selected from among all outdoor units of a first network performs a recognition process on the outdoor units and indoor units of the first network. In the first network, communication between individual devices including the outdoor units and the indoor units is performed by using a high frequency, and the recognition process performed by the selected outdoor unit uses a recognition signal having a low frequency.

System recognition is performed on devices connected to an identical system without recognizing a device of a different system as a device of the identical system in high-frequency communication. In a device network system, an outdoor unit selected from among all outdoor units of a first network performs a recognition process on the outdoor units and indoor units of the first network. In the first network, communication between individual devices including the outdoor units and the indoor units is performed by using a high frequency, and the recognition process performed by the selected outdoor unit uses a recognition signal having a low frequency.

An electric motor includes a rotor having an iron core to which a rotary shaft extending in a shaft center direction is fixed, and a stator disposed to face the rotor. The stator includes a plurality of teeth extending to the rotor, and a slot positioned between adjacent teeth among the plurality of teeth. The iron core includes a plurality of magnet insertion holes and a plurality of permanent magnets disposed in the plurality of magnet insertion holes, respectively, and the plurality of permanent magnets are rare earth magnets. An outermost peripheral shape of the iron core corresponding to a magnetic pole of each of the plurality of permanent magnets includes a plurality of arcs having different radii, the number of poles of the rotor is greater than or equal to 10, and a residual magnetic flux density of the permanent magnet is greater than or equal to 1.3T.

A fall prevention structure of an electric component cover in a refrigeration cycle apparatus includes an electric component box housing an electric component of a refrigeration cycle apparatus. The electric component box includes a casing, a side of which is open, and an electric component cover configured to cover, in an upright position, an opening of the casing and to be screwed to the casing. The electric component cover includes a catch including a backward-extending portion and an upward-extending portion. The backward-extending portion extends backward from an upper end portion of the electric component cover. The upward-extending portion extends upward from an end portion of the backward-extending portion. In a state in which the electric component cover is screwed to the casing, the catch is inserted into an insertion slot disposed in a portion extending in an up-down direction of the casing. When the electric component cover is unscrewed from the casing, the electric component cover does not fall from the casing by the catch being caught by a portion above the insertion slot.

A configuration management system for a heating, ventilation, and air conditioning (HVAC) system includes a controller having a memory storing a baseline configuration of the HVAC system. The baseline configuration of the HVAC system indicates that the HVAC system is an air conditioning system or a heat pump system. Additionally, the controller is configured to determine a current configuration of the HVAC system based on detecting whether a reversing valve is present in the HVAC system. The current configuration of the HVAC system includes an air conditioning system configuration or a heat pump system configuration. The controller is also configured to perform a control action in response to determining that the current configuration is different than the baseline configuration.