Variable Speed Compressor Control for Refrigerant Parameter Estimation
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Solution Overview
Problem
Existing refrigeration systems with variable speed compressors face challenges in accurately calculating and monitoring critical parameters such as evaporator and condenser temperatures and pressures, which are essential for optimal operation and prevention of overheat or floodback conditions, due to the complexity of dynamic load variations and the need for precise energy efficiency management.
Innovation Solution
A system comprising a compressor connected to a condenser and evaporator, with sensors for condenser and discharge temperature signals, an inverter drive for modulating compressor speed, and a control module that calculates evaporator and evaporator pressures based on electrical power and compressor speed data, enabling monitoring of overheat and floodback conditions and calculation of compressor capacity, power consumption, and energy efficiency ratios.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If variable speed compressor is used to vary compressor capacity according to refrigeration system load, then energy efficiency is improved, but accurate calculation and monitoring of critical parameters (evaporator and condenser temperatures and pressures) becomes more difficult due to dynamic load variations
Solution Approach 1:
The control module continuously monitors electrical power data and compressor speed data from the inverter drive, and uses this feedback to dynamically calculate evaporator and condenser temperatures and pressures. This closed-loop feedback mechanism allows the system to adapt to dynamic load variations while maintaining accurate parameter calculation, resolving the contradiction between energy efficiency improvement and measurement precision.
Solution Approach 2:
The patent replaces direct mechanical sensing of temperatures and pressures with an electrical field-based calculation approach. By using electrical power data and compressor speed data from the inverter drive, the control module calculates the critical parameters through mathematical relationships rather than direct mechanical measurement, enabling accurate monitoring under variable speed conditions.
2Reliability
If multiple sensors and calculation algorithms are implemented to monitor critical parameters, then system reliability is improved, but device complexity increases
Solution Approach 1:
The control module serves multiple functions: it controls the inverter drive, monitors electrical power data, calculates evaporator and condenser temperatures, calculates pressures, and provides protection against abnormal conditions. By making the control module multi-functional, the patent achieves high system reliability without proportionally increasing device complexity, as one component performs multiple critical tasks.
Solution Approach 2:
The system uses its own operational data (electrical power data and compressor speed data from the inverter drive) to calculate and monitor critical parameters, rather than requiring separate dedicated sensors for each parameter. This self-service approach improves reliability through continuous monitoring while minimizing additional hardware complexity.
3Reliability
If real-time monitoring and calculation of all parameters is implemented, then protection against overheat and floodback conditions is improved, but loss of processing time and computational resources increases
Solution Approach 1:
The control module continuously calculates evaporator and condenser temperatures and pressures in real-time using pre-established mathematical relationships based on electrical power data and compressor speed data. By performing these calculations continuously and proactively rather than reactively, the system maintains up-to-date parameter information ready for immediate protection decisions, reducing processing delays when abnormal conditions occur.
Data Source
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AI summary
A system and method for calculating parameters for a refrigeration system having a variable speed compressor is provided. A compressor is connected to a condenser and an evaporator. An evaporator sensor outputs an evaporator signal corresponding to at least one of an evaporator pressure and an evaporator temperature. An inverter drive modulates electric power delivered to the compressor to modulate a speed of the compressor. The control module is connected to the inverter drive and receives the evaporator signal, monitors electrical power data and compressor speed data from said inverter drive, and calculates at least one of a condenser temperature and a condenser pressure based on the evaporator signal, the electrical power data, and the compressor speed data.