Low Voltage DC-DC Converter Thermal Management via Mode Switching
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Solution Overview
Problem
Low voltage DC-DC converters in vehicles are prone to overheating due to overload, leading to forced shutdowns when cooling systems are not available, which destabilizes the battery charging and affects the overall motor system reliability.
Innovation Solution
A control apparatus comprising a comparator, adjuster, and controller that compares the heat release temperature with a criterion temperature, adjusts the criterion current value, and converts the control mode of the DC-DC converter to either constant current or constant voltage modes to prevent overheating and maintain operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the LDC operation is forcedly stopped to lower heat release temperature, then the temperature is reduced, but the battery charging stability deteriorates and system reliability decreases
Solution Approach 1:
The patent applies dynamics by making the control mode adjustable between PWM and PFM based on temperature conditions. The controller dynamically switches between continuous PWM mode and frequency-modulated PFM mode, allowing the system to adapt to varying thermal conditions while maintaining operation and preventing forced shutdowns.
Solution Approach 2:
The patent changes the control parameter from fixed PWM to variable PFM mode. When temperature exceeds the threshold, the controller switches to PFM mode where the switching frequency varies according to the temperature difference, effectively reducing power loss and heat generation while maintaining continuous operation.
2Temperature
If additional cooling fan or forced air cooling is added to reduce heat release temperature, then temperature control improves, but device complexity increases
Solution Approach 1:
The patent applies self-service by using the LDC's own control system to regulate its temperature through mode switching. The controller monitors temperature and automatically adjusts between PWM and PFM modes, making the system self-regulating without requiring external cooling fans or forced air cooling systems.
Solution Approach 2:
The patent replaces mechanical cooling systems (fans, forced air cooling) with an electronic control solution. By substituting physical cooling mechanisms with a control algorithm that switches between PWM and PFM modes, the system achieves temperature management without additional mechanical components.
3Temperature
If the criterion current value is reduced to limit power loss, then heat release temperature decreases, but output power capability is reduced
Solution Approach 1:
The patent applies dynamics by making the current limit adaptive rather than fixed. In PFM mode, the current limit is dynamically adjusted based on temperature conditions, allowing the system to maintain higher power capability when cool and reduce power (and heat) generation when hot, optimizing both thermal management and power delivery.
Data Source
AI summary
Disclosed are an LDC control apparatus for preventing an LDC from being overheated, and a method of operating the same. The LDC control apparatus includes a comparator configured to compare a heat release temperature of an LDC with a predetermined criterion temperature, an adjustor configured to adjust a predetermined criterion current value according to a result of the comparison of temperature, and a controller configured to compare the adjusted criterion current value with an output current value being output from the LDC, and control the LDC by converting a control mode of the LDC according to a result of the comparison of current.