Transport Climate Control Load Adjustment for C-Rate Stability
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Solution Overview
Problem
Rechargeable Energy Storage Systems (RESS) experience fluctuations in charge and discharge rates (C-Rate), which can lead to reduced system life and inefficient power usage in vehicles and transport containers equipped with climate control systems.
Innovation Solution
Implementing a method to adjust the operation of electrically powered accessories as variable loads, increasing or decreasing power consumption based on determined C-Rate thresholds to stabilize charge and discharge rates, thereby optimizing power usage and extending the life of the RESS.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the climate control system operates continuously to maintain environmental conditions, then cargo safety and passenger comfort are ensured, but C-Rate fluctuations increase and RESS life is reduced
Solution Approach 1:
The climate control system transitions from continuous operation to dynamic operation, adjusting its load based on real-time C-Rate conditions. The controller modulates the compressor and fan operations to match power availability from the RESS, enabling the system to adapt between high-power and low-power modes while maintaining cargo safety and extending RESS life.
Solution Approach 2:
The system changes operational parameters (compressor speed, fan speed, refrigerant flow) based on C-Rate thresholds. When C-Rate exceeds thresholds, the controller reduces power consumption by adjusting these parameters, thereby protecting the RESS while maintaining adequate climate control functionality.
2Duration of action of stationary object
If the C-Rate threshold is set low to protect the RESS, then RESS life is extended, but climate control performance may be compromised
Solution Approach 1:
The controller implements periodic monitoring of C-Rate and adjusts climate control operations in cycles. When C-Rate exceeds the threshold, the system enters a reduced-power mode temporarily, then returns to normal operation when conditions improve. This periodic adjustment allows the system to protect the RESS while maintaining overall climate control performance through cumulative operation.
3Reliability
If the C-Rate threshold is set high to maintain climate control performance, then climate control reliability is improved, but RESS life is reduced
Solution Approach 1:
The controller continuously monitors C-Rate and uses this feedback to adjust climate control system operation. When C-Rate approaches the threshold, the system proactively reduces load; when C-Rate decreases, the system increases load. This closed-loop feedback mechanism optimizes the balance between climate control performance and RESS protection, extending RESS life while maintaining adequate performance.
Data Source
Figure 1A
Figure 1B
Figure 1C
AI summary
A method of minimizing C-Rate fluctuations with an electrically powered accessory (EPA) is disclosed. The EPA is configured to be used with at least one of a vehicle, a trailer, and a transport container that has a first controller. The EPA has a second controller. The method includes determining, by the first controller, a first C-Rate of a Rechargeable Energy Storage System (RESS). Also, the method includes comparing the first C-Rate to a first predetermined threshold. The method also includes when the first C-Rate exceeds the first predetermined threshold, the first controller sending a first request to the second controller to adjust a load of the EPA. The method further includes the second controller determining a first operational mode of the EPA based on the first request. Also the method includes when the first operational mode of the EPA allows a load change, the second controller adjusting the load of the EPA.