Reciprocating Compressor Stroke Control from Half-Wave Sensing
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Solution Overview
Problem
Conventional reciprocating compressor control systems incur high costs and power consumption due to the need to detect both positive and negative half-wave values of voltage and current, which can be mitigated by detecting only one half-wave value and estimating the other based on it.
Innovation Solution
An apparatus and method that includes a voltage detecting unit for detecting a positive half-wave voltage, a current detecting unit for detecting a positive half-wave current, a voltage and current estimating unit to estimate the negative half-wave values, and a stroke controller to adjust the compressor stroke based on estimated values, using a simpler power source that applies only positive DC power.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If both positive and negative half-wave values of voltage and current are detected, then measurement accuracy is improved, but device complexity and power consumption increase
Solution Approach 1:
The patent extracts only the necessary portion of the waveform (positive half-wave) for detection purposes. By detecting only the positive half-wave values of voltage and current, the system eliminates the need for complex dual-polarity detection circuits while maintaining sufficient measurement capability for stroke control.
Solution Approach 2:
The patent creates a simplified copy of the detection function by using the positive half-wave detection results to represent the entire AC cycle characteristics. The detected positive half-wave values are used to calculate stroke through established relationships, eliminating the need for direct negative half-wave measurement.
2Measurement precision
If both positive and negative half-wave values of voltage and current are detected, then measurement precision is improved, but power consumption increases
Solution Approach 1:
The patent extracts only the essential information from the AC waveform (positive half-wave) for control purposes. This extraction approach reduces the active detection time and circuit operation duration, directly lowering power consumption while retaining sufficient data for accurate stroke calculation.
Solution Approach 2:
The patent applies partial action by detecting only the positive half-wave portion of the AC cycle rather than the complete waveform. This partial detection provides adequate information for stroke control while significantly reducing the energy required for continuous full-waveform monitoring.
3Device complexity
If only positive half-wave values are detected, then device complexity and power consumption are reduced, but measurement completeness deteriorates
Solution Approach 1:
The patent uses feedback mechanisms where the detected positive half-wave values are processed through calculation algorithms that reconstruct the necessary stroke information. The system continuously monitors and adjusts based on the detected values, ensuring accurate stroke control despite incomplete direct waveform measurement.
Solution Approach 2:
The patent replaces the mechanical/electrical requirement for complete waveform detection with a computational approach. By substituting direct negative half-wave measurement with calculation based on positive half-wave data and system parameters, the patent recovers the lost information through mathematical relationships rather than physical measurement.
Data Source
AI summary
An apparatus for controlling an operation of a reciprocating compressor includes a voltage detecting unit for detecting a positive half-wave voltage of an AC voltage applied to a motor of the reciprocating compressor; a current detecting unit for detecting a positive half-wave current of the AC current passing through the motor; a voltage and current estimating unit for estimating a negative half-wave voltage of the AC voltage applied to the motor and a negative half-wave current of the AC current passing through the motor based on the detected positive half-wave voltage and the detected positive half-wave current; a stroke estimating unit for estimating a stroke of the reciprocating compressor based on the detected positive half-wave voltage and the detected positive half-wave current and the negative half-wave voltage and the negative half-wave current which have been estimated by the voltage and the current estimating unit; a stroke controller for outputting a stroke control signal of the reciprocating compressor based on a comparison value between the estimate stroke estimate value and a stroke reference value of the reciprocating compressor; and a power source unit for applying positive DC power to the voltage detecting unit and the current detecting unit.