Refrigerant Compressor Converter Sizing by Working-State Current
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Solution Overview
Problem
Existing methods for selecting frequency converters for refrigerant compressor units often result in unnecessary costs due to over-sizing, as they do not optimize the selection based on the specific working states and operating frequencies of the compressor units.
Innovation Solution
A method that determines the working state operating current value and start-up current value, allowing for the selection of a frequency converter with a maximum converter current value sufficient for reliable operation, while avoiding unnecessary large constructions, by using empirically determined drive data and storing these values for later utilization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If frequency converters are selected to not restrict possible working states of the refrigerant compressor, then the reliability and versatility of the compressor operation is improved, but the device cost increases due to unnecessary over-sizing
Solution Approach 1:
The patent applies preliminary action by pre-calculating and storing drive data (current values, power consumption) for various working states in a database before the frequency converter selection process. This allows the selection method to quickly retrieve and analyze pre-computed data, enabling optimized frequency converter selection without restricting necessary working states. The pre-computed drive data includes current values at different operating frequencies, which are stored and later used to determine the minimum required frequency converter capacity.
Solution Approach 2:
The patent employs parameter changes by analyzing the relationship between operating frequency and current consumption across different working states. By varying the operating frequency parameter and observing its effect on current consumption, the method identifies the actual current requirements for each working state. This allows selection of a frequency converter with appropriately sized current capacity, avoiding both over-sizing and under-sizing, thus resolving the contradiction between versatility and device size.
2Reliability
If frequency converters are selected based on maximum possible current requirements, then the reliability of operation across all working states is improved, but the cost-effectiveness deteriorates due to unnecessary large construction
Solution Approach 1:
The patent applies partial action by determining the frequency converter size based on the actual partial requirements of specific working states rather than assuming maximum requirements for all possible states. The method calculates current values for each working state at its optimal operating frequency and selects a frequency converter that meets these specific requirements. This avoids the excessive action of sizing for absolute maximum current across all possible working states, thereby reducing device size while maintaining reliability for the intended application.
Solution Approach 2:
By pre-calculating and storing drive data including current values and power consumption for various working states, the patent enables a more accurate determination of actual frequency converter requirements. This preliminary analysis reveals that maximum current requirements are not needed for all working states, allowing selection of a smaller, more cost-effective frequency converter that still ensures reliable operation for the intended application scope.
3Measurement precision
If drive data is determined and stored in advance for each working state and operating frequency, then the precision of frequency converter selection is improved, but the data processing complexity and storage requirements increase
Solution Approach 1:
The patent applies preliminary action by pre-calculating and storing drive data (current values, power consumption) for various working states and operating frequencies in a database before the frequency converter selection process. This allows the selection method to quickly retrieve and analyze pre-computed data, enabling precise frequency converter selection without requiring complex real-time calculations. The pre-computed data includes current values at different operating frequencies, which are stored and later used to determine the minimum required frequency converter capacity.
4Device complexity
If the frequency converter is selected with maximum converter current value close to working state operating current value, then the cost-effectiveness is improved, but the risk of insufficient start-up current capability increases
Solution Approach 1:
The patent addresses this contradiction by pre-calculating and storing not only operating current values but also start-up current requirements for each working state in the database. This preliminary data preparation allows the selection method to simultaneously consider both operating current and start-up current requirements, ensuring that the selected frequency converter has sufficient capability for both scenarios without unnecessary over-sizing.
Data Source
AI summary
In order to improve a method for selecting a frequency converter for a refrigerant compressor unit that includes a refrigerant compressor and an electric drive motor such that the frequency converter is selected in a manner for optimized use, it is proposed that a working state suitable for operation of the refrigerant compressor unit should be selected within an application field of an application graph of the refrigerant compressor, that an operating frequency for this selected working state should be selected, and that a working state operating current value that corresponds to the selected working state and the selected operating frequency should be determined from drive data, for operation of the refrigerant compressor unit.