Compressor motor preheat control

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Dual compressor vapor cycle systems face issues with fluid migration, leading to lubricant starvation and flooded startup conditions in idle compressors, which affect system performance and reliability.

Innovation Solution

Implementing a control logic that selectively activates compressors and uses the idle compressor's electric motor to generate heat, maintaining a motor temperature range to prevent fluid migration, and incorporating a failsafe timer mechanism to prevent overheating.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of energy

If the idle compressor is left without heating, then energy consumption is reduced, but fluid migration occurs causing lubricant starvation and flooded startup conditions

Engineering Contradiction:

Improveenergy consumptionVSAvoidcompressor startup reliability

Core Design Contradiction:

Loss of energyVSReliability

Solution Approach 1:

The system performs preliminary heating of the idle compressor motor windings before startup to prevent fluid migration and lubricant accumulation. This advance action ensures that when the compressor is needed, it is ready for immediate reliable operation without flooded conditions, resolving the contradiction between energy savings and startup reliability.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system changes the temperature parameter of the idle compressor motor windings by applying controlled heating. This parameter change prevents fluid migration by maintaining the windings above the dew point, thereby preventing lubricant starvation and ensuring reliable startup while managing energy consumption through controlled heating cycles.

Inventive Principle:

Principle #35Parameter changes

2Reliability

If the idle compressor motor is heated continuously, then fluid migration is prevented, but overheating and component damage may occur

Engineering Contradiction:

Improvefluid migration preventionVSAvoidoverheating damage

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The system uses feedback control by monitoring the temperature of the idle compressor motor windings and adjusting the heating accordingly. The controller compares the measured temperature with target ranges and modulates heating power to maintain optimal temperature, preventing both fluid migration and overheating damage.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

Instead of continuous heating, the system applies periodic heating cycles to the idle compressor motor windings. This periodic action maintains sufficient temperature to prevent fluid migration while allowing cooling periods that prevent overheating and potential damage, thus resolving the contradiction between preventing fluid migration and avoiding overheating.

Inventive Principle:

Principle #19Periodic action

3Reliability

If the compressor startup is delayed to allow fluid to settle, then flooded startup conditions are reduced, but system cooling performance deteriorates

Engineering Contradiction:

Improvestartup condition stabilityVSAvoidcooling performance

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

The system performs preliminary heating of the idle compressor before startup to prevent fluid migration and lubricant accumulation. This preliminary action eliminates the need for delayed startup, allowing immediate compressor activation while maintaining reliable startup conditions and preserving cooling performance.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system replaces the mechanical approach of delayed startup with thermal management through controlled heating. Instead of waiting for fluids to settle mechanically, the system uses thermal energy to prevent fluid migration, enabling immediate startup without compromising either startup stability or cooling performance.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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

Prevents refrigerant and lubricant migration, ensuring the active compressor is not starved and reduces the risk of flooded startups, enhancing system reliability and cooling effectiveness.

Implementation Method 1

the control logic provides heating to an idle compressor to reduce or eliminate migration of refrigerant and/or lubricant in a liquid state into the idle compressor. The idle compressor has an electric motor that can be used to generate heat

Methodology Applied

Scientific EffectJoule heating: Joule Heating

Data Source

PatentEP2482012B1Compressor motor preheat control

Publication Date: 2020.05.06 HAMILTON SUNDSTRAND CORP

Figure 1
Figure 2
Figure 3

AI summary

A method of controlling a vapor cycle system (10) having first and second compressors (14,16) includes operating the first compressor (14) to compress refrigerant while the second compressor (16) is idle, sensing a motor temperature of the second compressor (16), activating a preheating mode in which the motor (16-1) of the second compressor (16) is powered to generate heat when the motor temperature of the second compressor is below a lower temperature threshold, turning off the preheating mode when the sensed motor temperature of the second compressor (16) is above an upper temperature threshold, and limiting the maximum duration of the preheating mode to a preheating time period, such that the preheating mode is turned off after being activated for the preheating time period.