Gas bearing compressor backup power
A compressor for a heat transfer circuit includes a variable frequency drive (VFD), an electric motor that rotates a driveshaft, bearing(s) for supporting the driveshaft, a backup gas supply, and a power supply. During a utility power interruption, the backup gas supply operates utilizing DC electrical power generated by a back electromotive force of the electric motor. A method of operating an electric power supply system for a compressor includes operating in a utility power mode and operating in a backup power mode during a utility power interruption. In the utility power mode, AC electrical power is supplied from the VFD to the motor. In the backup power mode, DC electrical power generated in the VFD by a back electromotive force of the motor it used to operate a backup gas supply to supply compressed working fluid to gas bearing(s) of the compressor.
1. A heating, ventilation, air conditioning, and refrigeration (HVACR) system comprising:
a heat transfer circuit including a compressor, the compressor including:
a driveshaft,
a variable frequency drive (VFD) configured to utilize utility power,
a permanent magnet motor electrically connected to the VFD, the permanent magnet motor configured to rotate the driveshaft and compress a working fluid in the heat transfer circuit, and
one or more gas bearings configured to support the driveshaft using the compressed working fluid;
a backup gas supply fluidly connected to the one or more gas bearings, the backup gas supply including one or more of a second compressor, a vessel, a vessel with an electric heater, and a condenser valve; and
a switch-mode power supply electrically connected to the VFD, wherein during an interruption in the utility power, the switch-mode power supply is configured to utilize DC electrical power generated by a back electromotive force of the permanent magnet motor to operate the backup gas supply to provide a flow of compressed working fluid to the one or more gas bearings.
2. The HVACR system of claim 1 , further comprising:
a controller to control the compressor, the controller configured to operate in a utility power mode and a backup power supply mode, wherein
in the utility power mode, the VFD receives the utility power and supplies power to the permanent magnet motor to rotate the driveshaft and compress the working fluid,
in the backup power supply mode, VFD generates the DC electrical power utilizing the back electromotive force of the permanent magnet motor, and the DC electrical power is used to power the controller to activate the backup gas supply.
3. The HVACR system of claim 2 , wherein in the backup power supply mode, the controller operates the backup gas supply utilizing electrical power supplied from the switch-mode power supply utilizing the DC electrical power.
4. The HVACR system of claim 1 , wherein the DC electrical power is supplied from the VFD to the switch-mode power supply.
5. The HVACR system of claim 1 , wherein the back electromotive force causes the permanent magnet motor to supply an AC electrical power to the VFD, the VFD converting the AC electrical power into the DC electrical power.
6. The HVACR system of claim 1 , wherein the back electromotive force generates the DC electrical power in the VFD, and the DC electrical power is supplied from the VFD to the switch-mode power supply.
7. The HVACR system of claim 1 , further comprising:
a controller to control the compressor, the switch-mode power supply configured to supply electrical power with lower voltage than then the DC electrical power to the controller.
8. The HVACR system of claim 1 , wherein the switch-mode power supply receives the DC electrical power generated by the back electromotive force at a first voltage and the DC electrical supplied from the switch-mode power supply to the controller is at a second voltage lower than the first voltage.
9. The HVACR system of claim 1 , wherein the backup compressed gas supply includes the second compressor, the second compressor being configured to operate by being powered by the switch-mode power supply utilizing the DC electrical power generated by the back electromotive force of the permanent magnet motor.
10. The HVACR system of claim 1 , wherein the VFD includes an inverter electrically connected to the permanent magnet motor, the back electromotive force of the permanent magnet motor generates AC electrical power supplied from the permanent magnet motor to the inverter, the inverter converting the AC electrical power into the DC electrical power.
11. The HVACR system of claim 1 , wherein the VFD includes a rectifier, a DC link, and an inverter in series, the rectifier configured to receive the utility power, and the switch-mode power supply is electrically connected between the DC link and the inverter.
12. The HVACR system of claim 1 , wherein the heat transfer circuit includes the compressor, a condenser, an expander, and an evaporator fluidly connected.
13. A heat transfer circuit for a heating, ventilation, air conditioning, and refrigeration (HVACR) system comprising:
a compressor including:
a driveshaft,
a variable frequency drive (VFD) configured to utilize utility power,
a permanent magnet motor electrically connected to the VFD, the permanent magnet motor configured to rotate the driveshaft and compress a working fluid in the heat transfer circuit, and
one or more gas bearings configured to support the driveshaft using the compressed working fluid;
a backup gas supply fluidly connected to the one or more gas bearings, the backup gas supply including one or more of a second compressor, a vessel, a vessel with an electric heater, and a condenser valve; and
a switch-mode power supply electrically connected to the VFD, wherein during an interruption in the utility power, the switch-mode power supply is configured to utilize DC electrical power generated by a back electromotive force of the permanent magnet motor to operate the backup gas supply to provide a flow of compressed working fluid to the one or more gas bearings.
14. The heat transfer circuit of claim 13 , further comprising:
a controller to control the compressor, the controller configured to operate in a utility power mode and a backup power supply mode, wherein
in the utility power mode, the VFD receives the utility power and supplies power to the permanent magnet motor to rotate the driveshaft and compress the working fluid,
in the backup power supply mode, VFD generates the DC electrical power utilizing the back electromotive force of the permanent magnet motor, and the DC electrical power is used to power the controller to activate the backup gas supply.
15. The heat transfer circuit of claim 14 , wherein in the backup power supply mode, the controller operates the backup gas supply utilizing electrical power supplied from the switch-mode power supply utilizing the DC electrical power.
16. The heat transfer circuit of claim 13 , wherein the DC electrical power is supplied from the VFD to the switch-mode power supply.
17. The heat transfer circuit of claim 13 , wherein the back electromotive force causes the permanent magnet motor to supply an AC electrical power to the VFD, the VFD converting the AC electrical power into the DC electrical power.
18. The heat transfer circuit of claim 13 , wherein the back electromotive force generates the DC electrical power in the VFD, and the DC electrical power is supplied from the VFD to the switch-mode power supply.
19. The heat transfer circuit of claim 13 , wherein the backup gas supply includes the second compressor, the second compressor being configured to operate by being powered by the switch-mode power supply utilizing the DC electrical power generated by the back electromotive force of the permanent magnet motor.
20. The heat transfer circuit of claim 13 , wherein the VFD includes a rectifier, a DC link, and an inverter in series, the rectifier configured to receive the utility power, and the switch-mode power supply is electrically connected between the DC link and the inverter.