Frequency Converter Cooling in Vehicle Heat Pump Systems
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Solution Overview
Problem
Existing heating and air conditioning systems for vehicles, particularly in heat pump mode, face challenges in effectively cooling the frequency converter/inverter, leading to potential temperature drops that can cause inefficiency or damage due to excessive refrigerant cooling, especially when outside temperatures are low.
Innovation Solution
The system design allows for over 70% of the frequency converter/inverter's heat dissipation to be cooled with air in heat pump operation and with refrigerant suction gas in air conditioning mode, using a refrigerant line configuration that can be switched by valves to optimize cooling based on temperature and cooling requirements, ensuring the frequency converter/inverter is not excessively cooled.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the frequency converter/inverter is cooled by refrigerant suction gas in heat pump mode, then cooling efficiency is improved, but the temperature drops too low causing insufficient power electronics operation and condensation damage
Solution Approach 1:
The system dynamically switches between two cooling modes (heat pump mode with refrigerant cooling and air conditioning mode with air cooling) based on operating conditions. The frequency converter's cooling method is not fixed but adapts to the system's operational state, preventing excessive cooling in heat pump mode while ensuring adequate cooling in air conditioning mode.
Solution Approach 2:
The invention changes the cooling parameter (from refrigerant suction gas to ambient air) based on the operating mode. In heat pump mode, the frequency converter is cooled by ambient air rather than refrigerant suction gas, changing the cooling medium parameter to prevent temperature from dropping too low and causing reliability issues.
2Temperature
If the frequency converter/inverter is cooled by ambient air in air conditioning mode, then cooling is sufficient, but the temperature is not low enough to effectively dissipate heat
Solution Approach 1:
The cooling method dynamically adapts to the operating mode. In air conditioning mode, the system uses ambient air cooling for the frequency converter, which is sufficient for the lower heat dissipation requirements of this mode, while in heat pump mode it switches to refrigerant suction gas cooling for more effective heat removal.
Solution Approach 2:
The invention changes the cooling parameter based on operational requirements. In air conditioning mode, ambient air is used as the cooling medium which provides adequate cooling for the frequency converter's heat dissipation needs, while in heat pump mode the system switches to refrigerant suction gas for enhanced cooling capability.
3Adaptability or versatility
If a fixed refrigerant line configuration is used, then system complexity is reduced, but the system cannot adapt to different operating modes (heat pump and air conditioning)
Solution Approach 1:
The refrigerant line system is segmented into multiple paths with different cooling configurations. One path provides cooling for the frequency converter in heat pump mode, while another path provides cooling in air conditioning mode. This segmentation allows the system to adapt to different operating modes by activating the appropriate refrigerant line path.
Solution Approach 2:
The refrigerant system is designed with multi-functionality to serve both heat pump and air conditioning modes. The refrigerant lines are configured to provide appropriate cooling for the frequency converter in both operating modes, making the system universal across different operational states without requiring separate dedicated cooling systems.
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
This approach prevents excessive cooling that could lead to inefficiency or damage, maintaining optimal operating temperatures for the frequency converter/inverter in both heat pump and air conditioning modes, while ensuring effective cooling is maintained according to the system's requirements.
Implementation Method 1
the frequency converter/inverter can be cooled by air to over 70% of its heat dissipation rate in heat pump operation
Implementation Method 2
dissipating the heat energy
Implementation Method 3
the frequency converter/inverter can be cooled by over 70% of its heat dissipation via a heat exchanger connection in at least one refrigerant line path
Implementation Method 4
the frequency converter/inverter is cooled by the cold refrigerant flowing as suction gas
Data Source
Figure 1
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AI summary
The invention relates to a heating and air conditioning system (1) for a vehicle, which is designed to be operated for heating in heat pump mode and switchably for cooling in air conditioning mode, with a refrigerant circuit (3) comprising at least one electrically operated compressor (5), an outdoor air heat exchanger (7), an expansion element (9, 13), and an indoor air heat exchanger (11). The speed of the compressor (5) is controllable via a frequency converter/inverter (33), wherein the frequency converter/inverter (33) is arranged such that, in air conditioning mode, it can be cooled by over 70% of its heat dissipation via a heat exchanger connection in at least one refrigerant line configuration by refrigerant flowing downstream from the indoor air heat exchanger (11) to the compressor (5) as a suction gas in the refrigerant circuit (3), and in heat pump mode, it can be cooled by air to over 70% of its heat dissipation.