Motor Braking Assembly for Compressor Rotor Backflow Protection
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Solution Overview
Problem
In air conditioning systems, when power is lost or the motor drive experiences a fault, the rotor can spin backwards due to refrigerant vapor backflow, potentially damaging the active magnetic bearing assembly and rotor.
Innovation Solution
A motor braking assembly is introduced, comprising switches and braking resistors that are normally open but switch to a closed state upon power disruption, shorting the motor windings through the resistors to quickly stop the rotor, with fuses and a drive controller ensuring safe operation and protection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the motor drive experiences a fault or power loss, then the rotor can spin backwards due to refrigerant vapor backflow, but this causes damage to the active magnetic bearing assembly and rotor
Solution Approach 1:
The braking assembly is pre-configured with switches and braking resistors that automatically activate upon power disruption to counteract the harmful backward rotation before it can damage the magnetic bearing assembly and rotor
Solution Approach 2:
The braking resistors and switches are positioned and wired in advance during system assembly, ready to immediately short the motor windings through the resistors when power is lost, ensuring rapid protection without requiring complex real-time control decisions
2Reliability
If a motor braking assembly is added to prevent backward rotation, then component protection is improved, but device complexity increases
Solution Approach 1:
The braking assembly uses the existing motor windings and power disruption detection capability of the drive system, making the protection function utilize already-present components rather than requiring entirely separate systems
Solution Approach 2:
The braking assembly automatically activates upon power disruption without requiring external control signals or complex control logic, as the loss of power itself triggers the switches to close and engage the braking resistors
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
The motor braking assembly effectively prevents damage to the active magnetic bearing and rotor by rapidly stopping the rotor during power loss, enhancing component protection and system reliability.
Implementation Method 1
the at least one switch assumes a closed state shorting windings of the motor through the at least one braking resistor
Data Source
AI summary
An air conditioning system including a compressor having a motor; a condenser; an evaporator; a drive providing multiphase, AC output to the motor; a motor braking assembly electrically connected to the drive, the motor braking assembly including at least one switch and at least one braking resistor; wherein the at least one switch is held in an open state by power from the drive; wherein upon disruption of power to the motor, the at least one switch assumes a closed state shorting windings of the motor through the at least one braking resistor.