Compressor Motor Current Estimation from Capacitor Voltage
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Solution Overview
Problem
Existing compressor control systems require continuous detection of motor current using sensors, which is costly and prone to noise, limiting their accuracy and reliability.
Innovation Solution
An apparatus and method that calculate motor current by detecting capacitor and drive voltage values, performing a definite integral on the capacitor voltage values, eliminating the need for motor current sensors and enhancing resolution and noise resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If motor current is detected continuously using sensors, then control accuracy is improved, but system cost and complexity increase
Solution Approach 1:
The patent extracts the motor current detection function from the traditional sensor-based approach and implements it through mathematical calculation using voltage measurements. By removing the physical current sensor and replacing it with a calculation method based on capacitor voltage and drive voltage, the system achieves current detection without the complexity and cost of dedicated current sensing hardware.
Solution Approach 2:
The patent substitutes the mechanical/electrical sensor system with a mathematical computation system. Instead of using physical sensors to measure current directly, the system uses mathematical operations (definite integration) on voltage signals to derive current information, replacing hardware-based measurement with software-based calculation.
2Ease of manufacture
If differentiator or differentiation circuit methods are used to calculate motor current, then sensor cost is reduced, but noise resistance and resolution deteriorate
Solution Approach 1:
The patent inverts the traditional differentiation approach by using integration instead. While conventional methods use differentiators to calculate current from voltage, this patent applies definite integration to the capacitor voltage signal, which mathematically provides better noise filtering properties and higher resolution while still eliminating the need for current sensors.
3Reliability
If motor current sensors are used for compressor control, then control reliability is improved, but system cost increases
Solution Approach 1:
The patent enables the system to determine motor current using only voltage measurements that are already available in the control system. By utilizing the capacitor voltage and drive voltage signals that are inherently present in the compressor control circuitry, the system performs self-diagnosis and self-measurement without requiring external current sensors, thereby maintaining reliability while reducing cost.
Data Source
AI summary
An apparatus and method for controlling a compressor are provided. A motor current flowing in a compressor may be calculated from voltage values of a capacitor without using a sensor, and as a motor current value is calculated by changing voltage values of the capacitor according to voltage values of a drive and performing a definite integral thereon, the motor current value may be resistant to noise, and the compressor may be more stably controlled.