Gas Bearing Compressor Backup Power Using Motor Back-EMF Generation
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Solution Overview
Problem
Conventional HVACR systems face issues with compressor operation during utility power interruptions, leading to potential damage from loss of compressed gas flow to gas bearings, which can be costly and require frequent maintenance when using battery-based uninterruptible power supplies.
Innovation Solution
The system employs a permanent magnet motor's back electromotive force to generate DC power, which is used by a switch-mode power supply to activate a backup gas supply, ensuring continuous compressed gas flow to gas bearings during power outages, thereby preventing damage and reducing maintenance costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If battery-based uninterruptible power supplies are used to maintain compressed gas flow to gas bearings during power outages, then the gas bearings can continue to support the driveshaft, but the system complexity and maintenance costs increase significantly
Solution Approach 1:
The permanent magnet motor automatically generates electrical power through back electromotive force during power outages, eliminating the need for external battery systems. The motor's inherent electromagnetic properties are utilized to self-power the backup gas supply, reducing system complexity while maintaining reliability.
Solution Approach 2:
The permanent magnet motor serves dual functions: it acts as a motor during normal operation to drive the compressor, and as a generator during power outages to power the backup gas supply. This multi-functionality eliminates the need for separate backup power components, reducing overall system complexity.
2Reliability
If battery-based uninterruptible power supplies are used to maintain compressed gas flow to gas bearings, then the driveshaft continues to be supported, but maintenance costs and operational expenses increase
Solution Approach 1:
The system uses its own motor to generate the required electrical power during outages through back electromotive force, eliminating the need for external battery systems that incur maintenance costs. The motor's inherent electromagnetic properties are utilized to self-power the backup gas supply.
Solution Approach 2:
Instead of discarding the motor's back electromotive force as a transient phenomenon, the system recovers this electrical energy and utilizes it to power the backup gas supply, converting what would be wasted energy into a useful function that maintains bearing operation during outages.
3Device complexity
If conventional power systems are used without backup power generation, then the system is simpler, but the gas bearings lose compressed gas flow during power outages causing damage to the driveshaft and bearings
Solution Approach 1:
The permanent magnet motor automatically generates electrical power through back electromotive force during power outages, eliminating the need for external battery systems. The motor's inherent electromagnetic properties are utilized to self-power the backup gas supply, reducing system complexity while maintaining reliability.
Solution Approach 2:
The system prepares for power outages by having the backup gas supply ready to activate immediately when utility power fails. The back electromotive force generation occurs automatically upon power loss, providing immediate counter-action to prevent bearing damage before it can occur.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This solution allows for uninterrupted operation of the compressor, preventing damage to the driveshaft and gas bearings during power interruptions and reducing maintenance and operational costs by utilizing the motor's back electromotive force to power a backup gas supply.
Implementation Method 1
DC electrical power generated by a back electromotive force of the permanent magnet motor
Implementation Method 2
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
Implementation Method 3
one or more gas bearings that support the driveshaft as the driveshaft rotates within the compressor
Data Source
AI summary
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.