Compressor Drive Circuit for Constant Power and Noise Control
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Solution Overview
Problem
Conventional compressor driving devices face challenges in maintaining constant input power, especially during load changes and rotational variations, leading to noise issues and inaccurate current detection, which complicates the configuration and reliability of the system.
Innovation Solution
A compressor driving device with a power conversion circuit, drive circuit, voltage detector, current detector, and controller that adjusts the duty ratio based on the product of detected voltage and current values to maintain constant power input, using inexpensive detection means and reducing harmonic components without additional heavy components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional current detection methods are used in compressor driving devices, then the configuration remains simple, but the measurement precision of input power is insufficient leading to inaccurate current detection
Solution Approach 1:
The patent combines voltage detection and current detection functions into a single integrated detection system. The detection device simultaneously measures both voltage and current values, multiplies them to obtain input power, and compares it with rated power to control compressor operation. This merging approach improves measurement precision while avoiding the complexity of separate detection systems.
2Object-affected harmful factors
If additional heavy components like coils are added to reduce noise, then noise reduction effectiveness improves, but the device complexity and cost increase
Solution Approach 1:
The patent replaces mechanical noise reduction components (such as coils) with an electronic control approach. By using a detection device that monitors input power and a controller that adjusts compressor operation based on detected values, the system achieves noise reduction through electronic regulation rather than mechanical filtration, thereby reducing device complexity and cost.
3Productivity
If the compressor operates without shutdown during overload, then productivity is maintained, but the reliability of operation decreases due to unsafe conditions
Solution Approach 1:
The patent implements a feedback control mechanism where the detection device continuously monitors input power by multiplying voltage and current values. When the detected input power exceeds the rated power, the controller receives feedback and automatically adjusts or shuts down the compressor to prevent unsafe operation. This feedback loop ensures both productivity maintenance through controlled operation and reliability through safety protection.
Data Source
AI summary
A compressor driving device includes: a controller that PWM drives a compressor; an inverter circuit unit that supplies power to an electric motor included in the compressor; a drive circuit that drives the inverter circuit unit according to a control signal; a voltage detector that detects a voltage that is output to the electric motor; and a current detector that detects a current that is output to the electric motor. When a product of a detection value of the voltage detector and a detection value of the current detector is greater than a predetermined comparison value, a duty ratio of the control signal is reduced to cause the input power supplied to the electric motor by the inverter circuit unit to have a predetermined input power level or less.