Electric Compressor Inverter Heating for Low-Temperature Heat Pumps
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Solution Overview
Problem
Vehicle air conditioning systems for electric and hybrid vehicles face challenges in weight and cost increases due to complex components and inefficient refrigerant heating performance, especially at low outside temperatures where frost forms, disrupting heating operations.
Innovation Solution
A vehicle air conditioning device with a heat pump cycle using an electric compressor and semiconductor-based power element for heating the refrigerant, integrated with the compressor and inverter, which enhances refrigerant heating performance while reducing weight and cost by utilizing high thermal resistance semiconductor devices to efficiently heat the refrigerant.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a hot water tank with built-in heater, piping and pumps are added to heat the refrigerant, then the heating performance is improved, but the device complexity and weight increase
Solution Approach 1:
The patent merges the inverter and hot water tank into a single integrated unit. The inverter housing serves dual purposes: as the enclosure for the inverter components and as the hot water tank for heating the refrigerant. This eliminates the need for separate heating components, piping, and pumps, thereby reducing device complexity while maintaining heating performance.
Solution Approach 2:
The inverter housing is designed to perform multiple functions: it encloses the inverter electronics, serves as a hot water tank for refrigerant heating, and provides structural support. This multi-functionality reduces the overall number of components needed in the system, addressing the contradiction between heating performance and device complexity.
2Loss of energy
If conventional semiconductor devices are used in the inverter, then the device cost is reduced, but the refrigerant heating performance decreases due to low thermal resistance
Solution Approach 1:
The patent changes the thermal resistance parameter of the semiconductor device by selecting materials and designs with inherently high thermal resistance properties. This allows the semiconductor device to effectively heat the refrigerant when integrated with the hot water tank, improving refrigerant heating efficiency without requiring additional heating components.
Solution Approach 2:
The inverter's semiconductor devices generate heat as a byproduct of their operation, and this heat is directly utilized to warm the refrigerant through the integrated hot water tank. This self-service approach converts waste heat into useful heating, improving energy efficiency without adding separate heating systems or incurring additional costs.
3Ease of manufacture
If the inverter is disposed away from the electric compressor, then the manufacturing flexibility is improved, but the refrigerant heating performance decreases
Solution Approach 1:
The patent merges the inverter and electric compressor into a closely integrated assembly where the inverter housing forms part of the compressor unit. This integration ensures that the refrigerant passes through the hot water tank immediately after compression, maximizing heat transfer efficiency while still allowing for flexible manufacturing through modular assembly processes.
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 effectively suppresses weight and cost increases while improving refrigerant heating performance, ensuring reliable heating operations even at low temperatures by using a semiconductor device as a heat source within the electric compressor and inverter system.
Implementation Method 1
an inverter for the electric compressor using a power element constituted by a semiconductor device having high thermal resistance; the inverter being disposed on the electric compressor so that the refrigerant compressed by the electric compressor is able to be heated by the power element
Data Source
AI summary
A refrigerant heating performance is increased while suppressing an increase in weight or cost. A vehicle air-conditioning device (10) is provided with a heat pump cycle (16) for heating operation in which an electric compressor (50) for compressing refrigerant, a vehicle-cabin-interior condenser (26), a throttle (52), and a vehicle-cabin-exterior heat exchanger (54) are connected in that order via refrigerant piping. An inverter for the electric compressor (50) in which a power element comprising a highly heat-resistant semiconductor device is used is disposed on the electric compressor (50) so that the refrigerant compressed by the electric compressor (50) can be heated by the power element. During heating operation of the heat pump cycle (16), the refrigerant is heated by the power element.