Boost Converter Thermal Management in EV Power Supply
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Solution Overview
Problem
In electric vehicle power supply systems, the large-capacity capacitor used for smoothing electric current can experience a surge current when the system main relay is closed, leading to a heat load on the boost converter, which can result in overheating and potential damage when the vehicle is under high load or has recently been turned off.
Innovation Solution
A power supply system that includes a cooler to manage the temperature of the boost converter and a controller to precharge the capacitor before the system main relay is closed, using the sub power supply and boost converter, and starting the cooler when the boost converter temperature exceeds a specified threshold to prevent excessive heat buildup.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the system main relay is closed to connect the electric power converter to the main power supply, then the electric power converter can receive power from the main power supply, but a large surge current flows into the capacitor causing a heat load on the boost converter
Solution Approach 1:
The patent applies preliminary action by precharging the capacitor through the boost converter before closing the system main relay. The controller activates the precharging function to charge the capacitor to a predetermined voltage level before the relay closes, thereby preventing surge current when the main power supply connects to the electric power converter.
Solution Approach 2:
The patent applies preliminary anti-action by using the precharging function to counteract the potential surge current before it occurs. The controller detects when the system main relay is about to close and activates the precharging function to charge the capacitor in advance, creating an opposing effect that prevents the harmful surge current from flowing when the relay closes.
2Reliability
If the boost converter is used for precharging the capacitor, then the capacitor can be charged before the relay is closed, but the boost converter generates heat causing a heat load
Solution Approach 1:
The patent applies periodic action by controlling the precharging function to operate only during specific periods when needed. The controller activates the precharging function periodically based on the state of the system main relay, specifically when the relay is about to close, rather than operating continuously. This reduces unnecessary heat generation while maintaining surge current prevention capability.
Solution Approach 2:
The patent applies feedback by having the controller monitor the system state and adjust the precharging function accordingly. The controller detects when the system main relay is about to close and activates the precharging function only at that moment, using feedback from the system state to control the timing and duration of precharging, thereby minimizing heat generation while ensuring reliable surge current prevention.
3Productivity
If the vehicle travels with a high load, then the boost converter operates at high power, but the temperature of the boost converter remains high even after the main switch is turned off
Solution Approach 1:
The patent applies preliminary action by precooling the boost converter before the precharging operation when the temperature is high. The controller detects high temperature conditions and activates the cooling function in advance before starting the precharging process, ensuring the boost converter is cooled sufficiently before undergoing precharging, thereby preventing excessive heat accumulation.
4Temperature
If the cooler is started to cool the boost converter, then the temperature of the boost converter is reduced, but the cooler operation time increases
Solution Approach 1:
The patent applies preliminary action by starting the cooling function in advance before the precharging operation when high temperature is detected. The controller activates the cooling function beforehand to reduce the temperature of the boost converter before precharging begins, thereby preventing excessive heat accumulation during precharging and reducing the need for prolonged cooler operation.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This configuration allows for precharging the capacitor without increasing the heat load on the boost converter, ensuring efficient and safe operation by cooling the boost converter when necessary, thereby preventing overheating and potential damage.
Implementation Method 1
a cooler configured to cool the boost converter; and a controller configured to cause the sub power supply and the boost converter to precharge the capacitor... when one of a temperature of the boost converter and a temperature of a coolant in the cooler is higher than a specified temperature threshold
Implementation Method 2
a boost converter including a low voltage end connected to the sub power supply and a high voltage end connected to the capacitor
Implementation Method 3
the electric power converter includes a capacitor that smooths an electric current (voltage) supplied from the power supply
Data Source
AI summary
A power supply system for a vehicle includes: a main power supply; an electric power converter including a capacitor; a relay; a sub power supply; a boost converter; a cooler; and a controller configured to cause the sub power supply and the boost converter to precharge the capacitor, when a main switch of the vehicle is turned on and before the relay is closed to connect the electric power converter to the main power supply. The controller is configured to perform one of a control i) and a control ii) when one of a temperature of the boost converter and a temperature of a coolant in the cooler is higher than a specified temperature threshold. The control i) being a control to start the precharging while starting up the cooler. The control ii) being a control to start up the cooler before the precharging.