Heat Pump Compressor Torque Compensation for Low Vibration
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Solution Overview
Problem
Heat pumps experience torque ripple in their electric motors and compressors, leading to increased noise emissions and reduced stability due to uneven torque distribution, which existing solutions like power electronics with variable frequency converters cannot fully compensate, and often require additional sensors that may detect false vibrations from bearing damage.
Innovation Solution
A method involving commissioning the electric motor, determining the counter-torque of the compressor, calculating the torque offset between the motor and compressor torque, and compensating for this offset to maintain constant angular speed, thereby reducing vibrations and noise through converter control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If power electronics with variable frequency converters are used to compensate torque ripple, then motor control precision is improved, but torque ripple compensation is still insufficient and device complexity increases
Solution Approach 1:
The method pre-determines the counter-torque characteristics of the compressor across different operating conditions during commissioning or setup. This preliminary characterization of the compressor's torque requirements allows the control system to proactively compensate for torque ripple by adjusting motor torque in advance, rather than reacting to vibrations after they occur. The pre-stored counter-torque data enables efficient real-time control without requiring complex real-time measurement and adjustment mechanisms.
2Measurement precision
If additional vibration detectors are added to measure torque differences, then torque ripple detection is improved, but device complexity increases and false detections from bearing damage may occur
Solution Approach 1:
The invention introduces an intermediary computational approach by calculating the required counter-torque based on compressor operating parameters (pressure, temperature, flow rate) rather than directly measuring torque differences with additional sensors. The control system acts as an intermediary that translates readily available operational data into torque compensation commands, avoiding the need for dedicated torque measurement sensors while achieving the same control objective.
Solution Approach 2:
The system uses existing sensors and control infrastructure to determine compressor counter-torque requirements without requiring external vibration detectors or additional measurement devices. The compressor's own operating parameters (which are already measured for control purposes) are utilized to infer torque characteristics, allowing the system to self-determine its torque compensation needs using resources already available in the system.
3Object-affected harmful factors
If torque ripple compensation is implemented across all load ranges, then vibration reduction is improved, but control complexity and computational requirements increase
Solution Approach 1:
The system pre-determines and stores counter-torque characteristics for the compressor across its entire operating range during commissioning or setup phases. This preliminary characterization creates a lookup table or stored data set that contains the optimal torque compensation values for various operating conditions. During normal operation, the control system simply retrieves the appropriate compensation values based on current operating parameters, avoiding the need for complex real-time calculations while maintaining effective torque ripple compensation across all load ranges.
Data Source
Figure 1~2
AI summary
A method for operating an electric motor (9) of a compressor (2) of a heat pump (1) is proposed, comprising at least the following steps: a) starting up the electric motor (9), b) determining a counter-torque of the compressor (2) based on the pressure and temperature of the refrigerant before and after the compressor, c) determining a torque offset between the torque applied by the electric motor (9) and the determined counter-torque of the compressor (2), d) operating the electric motor (9) such that the torque offset determined in step c) is compensated. The method serves to reduce vibrations and associated noise emissions during the operation of an electric motor (9) of a compressor (2) of a heat pump (1).Reducing vibrations can also advantageously extend the service life of the electric motor (9), since, for example, the damaging effect of vibrations on the bearings of the electric motor (9) can be avoided.