System and method of mode-based compressor speed control for refrigerated vehicle compartment
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Solution Overview
Problem
Refrigerated truck systems face challenges in maintaining accurate temperature control during transportation, especially when not connected to shore power, leading to excessive temperature variations that limit their use for fresh goods requiring tighter temperature maintenance.
Innovation Solution
A system comprising a mode module, shore power module, engine module, and battery module that dynamically adjusts the compressor speed based on temperature conditions, utilizing shore power, engine power, or battery power to optimize temperature control and conserve battery charge, allowing for efficient operation regardless of power source availability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the evaporator is operated to maintain temperature within the box during transportation, then temperature control is improved, but power consumption increases and battery charge is depleted
Solution Approach 1:
The system dynamically adjusts compressor speed based on operating mode (shore power, engine power, or battery power). During battery-powered operation, the compressor speed is limited to a third speed (lower than first and second speeds) to conserve battery charge, while still maintaining acceptable temperature control. This dynamic adjustment resolves the contradiction by adapting power consumption to available power sources.
Solution Approach 2:
The system changes the compressor speed parameter according to the power source availability. When shore power or engine power is available, the compressor can operate at higher speeds (first or second speed) for optimal temperature control. When battery power is the only source, the compressor speed is reduced to a third speed to balance temperature maintenance with battery conservation. This parameter change strategy resolves the energy consumption issue.
2Duration of action of moving object
If the compressor speed is limited to conserve battery charge, then battery life is extended, but temperature maintenance accuracy deteriorates
Solution Approach 1:
The system uses dynamic compressor speed adjustment with three distinct speed levels based on power availability. The third speed (used during battery mode) is optimized to provide sufficient cooling capacity while extending battery life. The system transitions between speed levels dynamically, ensuring temperature accuracy is maintained within acceptable ranges even at reduced speeds, thus resolving the contradiction between battery life and temperature precision.
Solution Approach 2:
The system pre-charges the battery using shore power or engine power before battery-powered operation begins. This preliminary charging action ensures the battery has sufficient charge to operate the compressor at the third speed for the required duration, allowing temperature maintenance without excessive battery depletion. This preliminary action resolves the contradiction by preparing energy reserves in advance.
3Use of energy by moving object
If the evaporator is not operated when battery is not being charged, then power consumption is reduced, but temperature variation increases
Solution Approach 1:
The system dynamically controls the evaporator based on power availability and temperature conditions. During battery mode, the evaporator operates at reduced capacity (third speed) to maintain temperature stability while conserving battery charge. The system continuously monitors temperature and adjusts compressor operation accordingly, resolving the contradiction between power consumption and temperature stability through dynamic adaptation.
Solution Approach 2:
The system uses temperature feedback to adjust compressor operation. Temperature sensors monitor the box temperature and provide feedback to the control system, which then adjusts the compressor speed appropriately. This feedback mechanism ensures temperature stability is maintained even when the compressor operates at reduced speeds during battery mode, resolving the contradiction between power consumption and temperature stability.
Data Source
AI summary
A system is provided that includes mode, shore power, engine, and battery modules. The mode module determines whether to operate in a shore power, engine, or battery mode based on parameters. The shore power module, while in the shore power mode, runs a compressor at a speed based on a temperature within a container of a vehicle and limits the speed to a first speed. A battery is charged based on utility power while in the shore power mode. The engine module, while in the engine mode, limits the compressor speed to a second speed. The battery, while in the engine mode, is charged based on power received from an alternator/generator. The battery module, while in the battery mode, limits the compressor speed to a third speed. While in the battery mode, the battery is not being charged based on power from a shore power source and the alternator/generator.