Compressor Speed Control Circuit for Low-GWP Air Conditioners
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Solution Overview
Problem
Existing air conditioners using low-global warming potential (GWP) refrigerants, such as refrigerant mixtures containing 1,2-difluoroethylene, face challenges in achieving high efficiency, with limited solutions available in the literature to enhance their performance.
Innovation Solution
An air conditioner design that includes a compressor driven by a motor with a power conversion device capable of adjusting the motor rotation rate based on air conditioning load, utilizing a rectifier circuit and capacitor configuration that eliminates the need for an electrolytic capacitor, and supports both single-phase and three-phase AC power sources, ensuring high annual performance factor (APF) and reduced circuit size and cost.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a refrigerant mixture containing 1,2-difluoroethylene is used, then the global warming potential is reduced, but the efficiency of the air conditioner decreases
Solution Approach 1:
The patent changes the operating parameters of the compressor motor by introducing a power conversion device that can adjust the motor rotation rate. This allows the system to optimize performance specifically for low-GWP refrigerants, transforming the energy efficiency parameter to compensate for the inherent efficiency loss when using alternative refrigerants like 1,2-difluoroethylene mixtures.
2Productivity
If the motor rotation rate is adjusted according to air conditioning load, then the annual performance factor is improved, but the device complexity increases
Solution Approach 1:
The power conversion device is designed to perform multiple functions: it converts AC power to suitable motor frequencies, adjusts motor rotation rates according to load conditions, and optimizes system performance. By consolidating these functions into a single device, the patent achieves high annual performance factor while managing device complexity through multi-functionality rather than multiple separate components.
3Stability of the object's composition
If an electrolytic capacitor is used on the output side of the rectifier circuit, then the voltage variation is smoothed, but the circuit size and cost increase
Solution Approach 1:
The patent extracts and eliminates the electrolytic capacitor from the circuit by redesigning the power conversion architecture. The system achieves voltage stabilization without this component, likely through alternative methods such as passive PFC circuits or control strategies that manage voltage variation without requiring large capacitive elements, thereby reducing circuit size and cost.
Solution Approach 2:
By removing the electrolytic capacitor, the patent replaces it with a simpler, more cost-effective circuit design. The alternative solution uses components that are either cheaper or have longer lifespan, eliminating the need for maintenance-prone electrolytic capacitors while achieving the same voltage smoothing function through different means.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution enables high efficiency and reduced costs by allowing motor rotation rate adjustment with the air conditioning load, achieving a high annual performance factor while using refrigerants with low GWP and lower flammability, comparable to R410A, without the need for electrolytic capacitors.
Implementation Method 1
a compressor that compresses a refrigerant mixture containing at least 1,2-difluoroethylene
Implementation Method 2
The rectifier circuit rectifies an AC voltage of the AC power source
Implementation Method 3
The capacitor is connected in parallel to an output side of the rectifier circuit and smooths voltage variation caused by switching in the power conversion device
Implementation Method 4
a motor that drives the compressor
Data Source
AI summary
In an air conditioner that uses a refrigerant mixture containing at least 1,2-difluoroethylene, high efficiency is achieved. The motor rotation rate of a compressor (100) can be changed in accordance with an air conditioning load, and thus a high annual performance factor (APF) can be achieved. In addition, an electrolytic capacitor is not required on an output side of a rectifier circuit (21), and thus an increase in the size and cost of the circuit is suppressed.