Electric compressor controller and refrigeration cycle device

1. An electric compressor controller that controls an electric rotary-type compressor mounted to a vehicle and configured as a two-stage compression refrigeration cycle device,

the electric compressor having an electric AC motor using an AC current, a suction port, a discharge port, and an intermediate-pressure port, the electric compressor operated by the electric motor to compress a refrigerant and configured to draw a low-pressure refrigerant from the suction port, to compress the low-pressure refrigerant to be a high-pressure refrigerant, to discharge the high-pressure refrigerant from the discharge port, and to draw an intermediate-pressure refrigerant from the intermediate pressure port to join the refrigerant being compressed, the intermediate-pressure refrigerant having an intermediate pressure between a pressure of the low pressure refrigerant and a pressure of the high pressure refrigerant,

the electric compressor controller comprising:

at least one processor configured to

determine whether an operation stop request is made or canceled, the operation stop request being a request to stop the electric compressor,

determine whether a two-stage compression mode is performed, the two-stage compression mode being performed when the intermediate-pressure refrigerant flows into the electric compressor from the intermediate-pressure port,

reduce a rotational speed of the electric motor while electric power is supplied to the electric motor by controlling the AC current applied to the electric motor, in response to the two-stage compression mode being performed and the operation stop request being made,

stop the electric motor after reducing the rotational speed of the electric motor,

restart the electric compressor in response to the operation stop request being canceled after stopping the electric compressor, and

increase a threshold value of the AC current applied to the electric motor, after the operation stop request is made and before reducing the rotation speed of the electric motor, wherein

in response to the AC current applied to the electric motor exceeding the threshold value, the electric compressor is further configured to stop supplying the electric power to the electric motor.

2. The electric compressor controller according to claim 1 , wherein the at least one processor is further configured to control the AC current applied to the electric motor so as to rotate the electric motor in a reversed rotational direction relative to a rotational direction of the electric motor in the two-stage compression mode, after reducing the rotational speed of the electric motor and before stopping the electric motor.

3. The electric compressor controller according to claim 1 , wherein

the electric motor has a stator coil, and

the at least one processor is further configured to further reduce the rotational speed of the electric motor by applying a DC current to the stator coil to excite the stator coil after reducing the rotational speed of the electric motor by controlling the AC current and before stopping the electric motor.

4. The electric compressor controller according to claim 1 , wherein the at least one processor is further configured to

determine whether the electric power is available for the electric compressor, and

reduce the rotational speed of the electric motor in response to determining that the electric power is available.

5. An electric compressor controller that controls an electric rotary-type compressor mounted to a vehicle and configured as a two-stage compression refrigeration cycle device,

the electric compressor having an electric AC motor using an AC current, a suction port, a discharge port, and an intermediate-pressure port, the compressor operated by the electric motor to compress a refrigerant and configured to draw a low-pressure refrigerant from the suction port, to compress the low-pressure refrigerant to be a high-pressure refrigerant, to discharge the high-pressure refrigerant from the discharge port, and to draw an intermediate-pressure refrigerant from the intermediate pressure port to join the refrigerant being compressed, the intermediate-pressure refrigerant having an intermediate pressure between a pressure of the low pressure refrigerant and a pressure of the high pressure refrigerant,

the electric compressor controller comprising:

at least one processor configured to

determine whether an electric power decreasing request is made or canceled, the electric power decreasing request being a request to decrease electric power supplied to the electric compressor,

determine whether a two-stage compression mode is performed, the two-stage compression mode being performed when the intermediate-pressure refrigerant flows into the electric compressor from the intermediate-pressure port,

reduce a rotational speed of the electric motor while the electric power is supplied to the electric motor by controlling the AC current applied to the electric motor, in response to the two-stage compression mode being performed and the electric power decreasing request being made,

control the rotational speed of the electric motor to be zero by controlling the AC current applied to the electric motor after reducing the rotational speed of the electric motor,

restart the electric compressor in response to the electric power decreasing request being canceled after controlling the rotational speed to be zero, and

increase a threshold value of the AC current applied to the electric motor, after the electric power decreasing request is made and before reducing the rotational speed of the electric motor, wherein

in response to the AC current applied to the electric motor exceeding the threshold value, the electric compressor is further configured to stop supplying the electric power to the electric motor.

6. A two-stage compression refrigeration cycle device for a vehicle, the refrigeration cycle device comprising:

an electric rotary-type compressor having an AC electric motor using an AC current, a suction port, a discharge port, and an intermediate-pressure port, the electric compressor operated by the electric motor to compress a refrigerant and configured to

draw a low-pressure refrigerant from the suction port,

compress the low-pressure refrigerant to be a high-pressure refrigerant,

discharge the high-pressure refrigerant from the discharge port, and

draw an intermediate-pressure refrigerant from the intermediate pressure port to join the refrigerant being compressed, the intermediate pressure refrigerant having an intermediate pressure between a pressure of the low pressure refrigerant and a pressure of the high pressure refrigerant;

a radiator that dissipates heat of the high-pressure refrigerant discharged from the discharge port by performing a heat exchange between the high-pressure refrigerant and air to be blown into a vehicle compartment;

a first pressure reducer that decompresses a refrigerant from the radiator to be the intermediate-pressure refrigerant;

a gas-liquid separator that separates the intermediate-pressure refrigerant from the first pressure reducer into a gas-phase refrigerant and a liquid-phase refrigerant;

a second pressure reducer that decompresses the liquid-phase refrigerant separated in the gas-liquid separator to be the low-pressure refrigerant;

an exterior heat exchanger that is configured to evaporate a refrigerant from the second pressure reducer by performing a heat exchange between the refrigerant from the second pressure reducer and an outside air from outside of the vehicle compartment, and to guide the refrigerant from the second pressure reducer to flow to the suction port;

an intermediate-pressure refrigerant passage that guides the gas-phase refrigerant separated in the gas-liquid separator to the intermediate-pressure port; and

a controller having at least one processor for controlling the electric compressor, the controller configured to

determine whether an operation stop request is made or canceled, the operation stop request being a request to stop the electric compressor,

determine whether a two-stage compression mode is performed, the two-stage compression mode being performed when the intermediate-pressure refrigerant flows into the electric compressor from the intermediate-pressure port,

determine whether electric power is available for the electric compressor,

reduce a rotational speed of the electric motor while the electric power is supplied to the electric motor by controlling the AC current applied to the electric motor, in response to the two-stage compression mode being performed, the operation stop request being made, and upon determining that the electric power is available,

stop the electric motor after reducing the rotational speed of the electric motor, and

restart the electric compressor after stopping the electric compressor in response to the operation stop request being canceled.

7. A two-stage compression refrigeration cycle device for a vehicle, the refrigeration cycle device comprising:

an electric rotary-type compressor having an AC electric motor using an AC current, a suction port, a discharge port, and an intermediate-pressure port, the electric compressor operated by the electric motor to compress a refrigerant and configured to

draw a low-pressure refrigerant from the suction port,

compress the low-pressure refrigerant to be a high-pressure refrigerant,

discharge the high-pressure refrigerant from the discharge port, and

draw an intermediate-pressure refrigerant from the intermediate pressure port to join the refrigerant being compressed, the intermediate-pressure refrigerant having an intermediate pressure between a pressure of the low pressure refrigerant and a pressure of the high pressure refrigerant;

a radiator that dissipates heat of the high-pressure refrigerant discharged from the discharge port by performing a heat exchange between the high-pressure refrigerant and air to be blown into a vehicle compartment;

a first pressure reducer that decompresses a refrigerant from the radiator to be the intermediate-pressure refrigerant;

a gas-liquid separator that separates the intermediate-pressure refrigerant from the first pressure reducer into a gas-phase refrigerant and a liquid-phase refrigerant;

a second pressure reducer that decompresses the liquid-phase refrigerant separated in the gas-liquid separator to be the low-pressure refrigerant;

an exterior heat exchanger that is configured to evaporate a refrigerant from the second pressure reducer by performing a heat exchange between the refrigerant from the second pressure reducer and an outside air from outside of the vehicle compartment, and to guide the refrigerant from the second pressure reducer to flow to the suction port;

an intermediate-pressure refrigerant passage that guides the gas-phase refrigerant separated in the gas-liquid separator to the intermediate-pressure port; and

a controller having at least one processor for controlling the electric compressor, the controller configured to

determine whether an electric power decreasing request is made or canceled, the electric power decreasing request being a request to decrease electric power supplied to the electric compressor,

determine whether a two-stage compression mode is performed, the two-stage compression mode being performed when the intermediate-pressure refrigerant flows into the electric compressor from the intermediate-pressure port,

reduce a rotational speed of the electric motor while the electric power is supplied to the electric motor by controlling the AC current applied to the electric motor, in response to the two-stage compression mode being performed and the electric power decreasing request being made,

control the rotational speed of the electric motor to be zero by controlling the AC current applied to the electric motor after reducing the rotational speed of the electric motor,

restart the electric compressor in response to the electric power decreasing request being canceled after controlling the rotational speed to be zero, and

increase a threshold value of the AC current applied to the electric motor, after the electric power decreasing request is made and before reducing the rotational speed of the electric motor, wherein

in response to the AC current applied to the electric motor exceeding the threshold value, the electric compressor is further configured to stop supplying the electric power to the electric motor.

8. An electric compressor controller that controls an electric rotary-type compressor mounted to a vehicle and configured as a two-stage compression refrigeration cycle device, the electric compressor having a suction port, a discharge port, an intermediate-pressure port, and an electric AC motor using an AC current, the electric motor having a stator coil, the electric compressor operated by the electric motor to compress a refrigerant and configured to draw a low-pressure refrigerant from the suction port, compress the low-pressure refrigerant to be a high-pressure refrigerant, discharge the high-pressure refrigerant from the discharge port, and draw an intermediate-pressure refrigerant from the intermediate pressure port to join the refrigerant being compressed, the intermediate-pressure refrigerant having an intermediate pressure between a pressure of the low pressure refrigerant and a pressure of the high pressure refrigerant, the electric compressor controller comprising:

at least one processor configured to

determine whether an operation stop request is made or canceled, the operation stop request being a request to stop the electric compressor,

determine whether a two-stage compression mode is performed, the two-stage compression mode being performed when the intermediate-pressure refrigerant flows into the electric compressor from the intermediate-pressure port,

reduce a rotational speed of the electric motor while electric power is supplied to the electric motor by controlling the AC current applied to the electric motor, in response to the two-stage compression mode being performed and the operation stop request being made,

reduce the rotational speed of the electric motor by applying a DC current to the stator coil to excite the stator coil after reducing the rotational speed of the electric motor by controlling the AC current and before stopping the electric motor,

stop the electric motor after reducing the rotational speed of the electric motor, and

restart the electric compressor in response to the operation stop request being canceled after stopping the electric compressor.

9. An electric compressor controller that controls an electric rotary-type compressor mounted to a vehicle and configured as a two-stage compression refrigeration cycle device, the electric compressor having an electric AC motor using an AC current, a suction port, a discharge port, and an intermediate-pressure port, the electric compressor operated by the electric motor to compress a refrigerant and configured to draw a low-pressure refrigerant from the suction port, compress the low-pressure refrigerant to be a high-pressure refrigerant, discharge the high-pressure refrigerant from the discharge port, and draw an intermediate-pressure refrigerant from the intermediate pressure port to join the refrigerant being compressed, the intermediate-pressure refrigerant having an intermediate pressure between a pressure of the low pressure refrigerant and a pressure of the high pressure refrigerant, the electric compressor controller comprising:

at least one processor configured to

determine whether an operation stop request is made or canceled, the operation stop request being a request to stop the electric compressor,

determine whether a two-stage compression mode is performed, the two-stage compression mode being performed when the intermediate-pressure refrigerant flows into the electric compressor from the intermediate-pressure port,

determine whether electric power is available for the electric compressor,

reduce a rotational speed of the electric motor while the electric power is supplied to the electric motor by controlling the AC current applied to the electric motor, in response to the two-stage compression mode being performed, the operation stop request being made, and upon determining the electric power is available,

stop the electric motor after reducing the rotational speed of the electric motor, and

restart the electric compressor in response to the operation stop request being canceled after stopping the electric compressor.