Battery Power Control for Mobile Refrigeration Runtime
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Solution Overview
Problem
Limited power sources, such as batteries, drain quickly when used for devices like compressors, leaving insufficient power for other essential functions like starting a vehicle, leading to inadequate refrigeration during extended periods of use.
Innovation Solution
A method and control unit that measure the voltage from the power source, calculate the estimated remaining runtime based on its rate of change, and adjust the power drawn to maintain a sufficient level by decreasing or increasing power as needed to ensure the specified criteria are met for as long as possible, particularly for mobile refrigeration systems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the compressor runs at full power to maintain refrigeration, then the refrigeration performance is improved, but the power source drains quickly and may not have sufficient power for vehicle starting
Solution Approach 1:
The compressor speed is made dynamically adjustable rather than fixed. The control unit continuously monitors voltage and adjusts the compressor speed accordingly, allowing the system to adapt between high-power refrigeration mode and power-saving mode to balance refrigeration performance with power source duration
Solution Approach 2:
A feedback control mechanism is implemented where the control unit monitors the voltage from the power source and uses this information to adjust the compressor speed. When voltage drops below a threshold, the system reduces compressor power consumption to prevent complete power depletion, ensuring both refrigeration needs and vehicle starting requirements are met
2Power
If the compressor is stopped early to preserve power for vehicle starting, then the power level is maintained for starting, but the refrigeration performance deteriorates due to insufficient cooling
Solution Approach 1:
Instead of completely stopping the compressor when power is low, the system applies partial action by reducing the compressor speed to a lower operating level. This allows the compressor to continue providing refrigeration at reduced capacity, maintaining adequate cooling while conserving enough power for vehicle starting
3Duration of action of moving object
If the voltage is monitored and compressor speed is adjusted dynamically, then the power source runtime is maximized, but the control system complexity increases
Solution Approach 1:
The control system is designed to be relatively autonomous, automatically monitoring voltage levels and adjusting compressor speed without requiring complex user intervention or sophisticated control algorithms. The system serves itself by using voltage information directly to control compressor power consumption, maximizing runtime with minimal added complexity
Data Source
AI summary
A method and a control unit for controlling a power level being drawn from a power source (26). Based on a determined rate of change of a measured voltage (1) an estimated remaining runtime is calculated. The estimated remaining runtime represents a time where specific run criteria will no longer be fulfilled if the present power level is maintained. The estimated remaining runtime is compared to a threshold value, and in case the estimated remaining runtime is shorter than the threshold value, the power drawn from the power source (26) is decreased. Thereby the runtime for the power source (26) is maximised. This is particularly useful if the power source is a limited power source, such as a battery (26), e.g. for running a compressor (27) for a movable refrigeration system (24). The invention is suitable for automotive applications.