Compressor Heating Using Pulsed DC to Prevent Refrigerant Migration
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Solution Overview
Problem
Vapor compressor type HVAC systems face refrigerant migration issues when idle, leading to compressor damage due to rapid vaporization, which current energy-inefficient resistance heaters fail to adequately address.
Innovation Solution
A compressor heating system utilizing a compressor drive controller to selectively provide pulsed direct current (DC) to the stator winding of the compressor motor, maintaining the compressor warm and preventing refrigerant migration through pulse width modulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If resistance heaters are used to keep the compressor warm, then refrigerant migration is prevented, but energy efficiency deteriorates
Solution Approach 1:
The patent applies periodic action by using pulsed DC current instead of continuous heating. The controller delivers intermittent heating pulses to the stator winding, which generates heat through electrical resistance. This periodic heating approach maintains the compressor temperature above the dew point to prevent refrigerant migration while consuming significantly less energy compared to continuous resistance heater operation.
Solution Approach 2:
The patent implements multi-functionality by making the stator winding serve dual purposes: motor operation and heating. The same stator winding that drives the compressor motor during normal operation is utilized as a heating element when the compressor is idle. This eliminates the need for separate resistance heaters, reducing component count and energy consumption while preventing refrigerant migration.
2Temperature
If continuous heating is applied to prevent refrigerant migration, then compressor temperature is maintained, but power consumption increases
Solution Approach 1:
The controller implements periodic action by delivering pulsed DC current to the stator winding at specific intervals rather than continuously. The heating pulses are timed and duration-controlled to maintain compressor temperature above the dew point only when necessary, significantly reducing average power consumption compared to continuous heating while effectively preventing refrigerant migration.
Solution Approach 2:
The system applies self-service by using the compressor's own stator winding as the heating element. The stator winding inherently possesses electrical resistance that generates heat when current flows through it. This eliminates the need for external heating components, and the system uses its existing motor components to serve the dual function of both motor operation and temperature maintenance.
3Use of energy by moving object
If pulsed DC is applied to stator winding, then energy efficiency improves, but heating uniformity may deteriorate
Solution Approach 1:
The patent applies local quality by targeting heating to specific regions where refrigerant migration is most likely to occur. The pulsed DC current is directed through the stator winding to generate heat locally in the compressor head and suction area, which are the critical zones for preventing refrigerant accumulation. This localized heating approach maintains temperature uniformity in critical areas while minimizing overall energy consumption.
Solution Approach 2:
The system implements feedback control by monitoring compressor temperature and adjusting the pulsed DC heating accordingly. The controller receives temperature signals and modulates the heating pulse duration and frequency to maintain the compressor temperature above the dew point. This feedback mechanism ensures temperature uniformity is maintained in critical areas while optimizing energy efficiency by applying heat only when and where needed.
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 approach efficiently heats the compressor, reducing refrigerant migration and extending its lifespan while achieving higher energy efficiency and compliance with regulatory power averaging requirements.
Implementation Method 1
selectively providing a pulsed direct current (DC) to a stator winding of a motor of the compressor
Data Source
AI summary
A compressor heating system includes a compressor drive controller electrically coupled to an outdoor controller configured to selectively implement a pulse width modulation algorithm to deliver a pulsed direct current (DC) from the compressor drive controller to at least one stator winding of a motor of a variable speed compressor to provide heat to the compressor to prevent refrigerant migration to the compressor when the compressor remains idle with respect to operating in a cooling or heating mode.