Scroll Compressor Restart Control for Reverse Rotation Detection

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Refrigeration systems with electric motor driven scroll compressors can experience unintended reverse operation due to transient power losses, leading to refrigerant pressure imbalances and subsequent overheating and shutdowns.

Innovation Solution

A control system that monitors refrigerant pressure at the suction side of the compressor, turns it off when pressures exceed a predetermined limit, and restarts it after a stabilization period to ensure proper direction of rotation, using timers to manage these operations and count repeated occurrences to prevent system failure.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If the compressor is cycled on and off with brief interruptions, then energy savings and operational flexibility are improved, but the risk of reverse operation increases due to pressure imbalances

Engineering Contradiction:

Improveoperational flexibilityVSAvoidcompressor operation stability

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The control system performs preliminary actions by monitoring suction pressure before allowing compressor restart. The system checks whether suction pressure has equalized with discharge pressure before permitting motor restart, preventing reverse operation caused by pressure imbalances during brief power interruptions

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The control system continuously monitors suction pressure and uses this feedback to determine when the compressor can safely restart. The feedback mechanism tracks pressure equalization and only permits restart when pressures are balanced, eliminating the reverse operation risk while maintaining cycling flexibility

Inventive Principle:

Principle #23Feedback

2Reliability

If the compressor operates continuously without cycling, then pressure equalization is maintained and reverse operation is prevented, but energy efficiency and operational adaptability decrease

Engineering Contradiction:

Improvepressure stabilityVSAvoidcompressor energy consumption

Core Design Contradiction:

ReliabilityVSUse of energy by moving object

Solution Approach 1:

Before each compressor restart, the control system performs a preliminary pressure equalization check. This preliminary action ensures pressures are balanced, allowing the compressor to cycle on and off efficiently without risking reverse operation, thus maintaining both reliability and energy efficiency

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The control system implements periodic monitoring of suction pressure at predetermined intervals after compressor shutdown. This periodic action verifies pressure equalization before each potential restart, enabling efficient cycling operations while preventing reverse operation through timed pressure checks

Inventive Principle:

Principle #19Periodic action

3Reliability

If the control system implements continuous pressure monitoring and restart delays, then reverse operation is prevented, but system complexity and response time increase

Engineering Contradiction:

Improvereverse operation preventionVSAvoidcontrol system complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The control system implements a predetermined delay period after compressor shutdown before allowing restart. This preliminary time delay automatically allows pressure equalization without complex monitoring, preventing reverse operation through simple temporal separation of shutdown and restart events

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The control system changes the operational parameter from continuous pressure monitoring to fixed time-delay control. By using a predetermined delay period instead of continuous monitoring, the system prevents reverse operation while minimizing complexity through a simple time-based control mechanism

Inventive Principle:

Principle #35Parameter changes

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

Automatically detects and corrects reverse compressor operation, preventing overheating and shutdowns, and restoring normal operation without service interruption in most cases.

Implementation Method 1

means for monitoring refrigerant pressure at a suction side of the compressor

Methodology Applied

Scientific EffectPressure monitoring:

Data Source

PatentUS8225621B2Detection and correction of reverse operation of a compressor in a refrigeration system

Publication Date: 2012.07.24 MARMON FOODSERVICE TECH INC

AI summary

A method and system for detecting and correcting unintended reverse or backward operation of an electric motor driven scroll compressor of a refrigeration system is characterized by monitoring the pressure at a suction side of the compressor during operation of the refrigeration and determining whether the pressure, after a first time interval following startup of the compressor, exceeds and remains in excess of a predetermined upper pressure limit for at least a second time interval. If it does, the compressor is turned off for a third time interval and is then restarted. The foregoing is repeated and if the compressor is turned off a selected number of times because of successive occurrences of high suction side pressures during operation of the refrigeration system in a chilling cycle, an error indication is generated and the refrigeration system is shut down.