Inverter Temperature Control in Refrigerant-Cooled Compressor Systems
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Solution Overview
Problem
In air conditioning apparatuses with integrated electric compressors and inverters, electronic components can be excessively cooled in low temperature environments, leading to potential damage due to refrigerant flow inertia after compressor stoppage, limiting operation guaranteed temperature ranges.
Innovation Solution
An air conditioning apparatus with an electric compressor, a drive unit, a temperature detection unit, and a control unit that reduces self-cooling or increases self-heat generation of the drive unit when the temperature falls below a predetermined reference temperature to prevent excessive cooling and maintain the electronic component's temperature above the minimum guaranteed level.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the protection temperature threshold is set to a higher value to prevent excessive cooling of electronic components, then the reliability of electronic components is improved, but the adaptability to low temperature environments deteriorates
Solution Approach 1:
The control unit performs preliminary heating of the electronic components by controlling the compressor to operate in a heating mode before normal cooling operation. This preliminary action raises the temperature of electronic components to above the protection threshold, preventing excessive cooling when the compressor stops, while still allowing the system to operate in low temperature environments.
2Reliability
If the compressor operates continuously to maintain electronic component temperature, then the reliability of electronic components is improved, but the energy consumption increases
Solution Approach 1:
Instead of continuous operation, the compressor operates periodically in heating mode to raise electronic component temperatures. The control unit monitors temperatures and activates heating only when needed, then allows normal cooling operation. This periodic heating approach maintains reliability while significantly reducing energy consumption compared to continuous operation.
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
Prevents the breakage of electronic components by controlling refrigerant flow and heat generation, ensuring the electronic component's temperature remains above the minimum guaranteed level even in low temperature environments.
Implementation Method 1
the refrigerant that has been circulated until then continues to flow into the compressor due to its inertia. This leads to a possibility that the electronic component is excessively cooled
Implementation Method 2
heat generation by the electronic component itself disappears while the refrigerant that has been circulated until then continues to flow into the compressor
Data Source
AI summary
An air conditioning apparatus includes an electric compressor, an inverter, a temperature detection element, and an ECU. The electric compressor compresses a refrigerant drawn from a refrigerant intake port and discharges the refrigerant from a refrigerant discharge port. The inverter is integrated with the electric compressor so as to be cooled by the drawn refrigerant, and operates the electric compressor according to a control signal. The temperature detection element detects a temperature of the inverter. The ECU outputs a control signal to control the inverter. The ECU performs any one or both of a control for reducing a self-cooling amount of the electric compressor and a control for increasing a self-heat generation amount of the inverter with respect to the inverter when the temperature detected by the temperature detection element is lower than a predetermined reference temperature.