Heat Pump Mode Transition Control via Compressor Speed Ratio
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Solution Overview
Problem
Heat pumps in vehicles experience significant changes in control signals when transitioning between heating and cooling modes, which can be objectionable to occupants and lead to degradation of components, as well as increased noise and reduced durability.
Innovation Solution
A method and system that seamlessly transition between heat pump modes by combining the outputs of evaporator and refrigerant pressure controllers, maintaining a consistent compressor command through the use of PID controllers and feed-forward terms to minimize changes in compressor speed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the heat pump transitions between heating and cooling modes by changing refrigerant flow path, then the heat pump can provide both heating and cooling functions, but the control signals change significantly causing objectionable noise and component degradation
Solution Approach 1:
The patent changes the control parameter from raw controller outputs to compressor speed ratio (N2/N1). By using the ratio of compressor speeds as the control parameter during mode transitions, the system maintains smooth compressor operation and avoids abrupt control signal changes that cause noise and component degradation, while still achieving both heating and cooling functions.
2Adaptability or versatility
If the heat pump transitions between heating and cooling modes, then the system can adapt to different environmental conditions, but the compressor speed changes significantly causing noise and reduced durability
Solution Approach 1:
The patent transforms the control approach by using compressor speed ratio (N2/N1) as the controlling parameter. This parameter change ensures that during mode transitions, the compressor speed adjustment is gradual and controlled, preventing abrupt changes that would cause noise and reduce durability, while maintaining the ability to adapt to different heating and cooling conditions.
3Adaptability or versatility
If different controllers are used for different operating modes, then each controller can be optimized for its specific mode, but the transition between modes causes significant control signal changes
Solution Approach 1:
The patent introduces a unified control parameter (compressor speed ratio N2/N1) that bridges different operating modes. Instead of switching between different control signals, the system maintains control signal stability by adjusting the compressor speed ratio, which provides a smooth transition while still allowing mode-specific control optimization through the ratio parameter.
Data Source
AI summary
Methods and system for operating a heat pump in different operating modes and providing a predictable heat pump response when the heat pump is transitioned between the different operating modes are presented. In one example, a controller that includes executable instructions for providing a bumpless compressor command for operating the heat pump is disclosed.