EV Power Converter Thermal Protection via Indirect Sensor Estimation
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Solution Overview
Problem
Power converters in electric vehicles face challenges in protecting current sensors from overheating, as existing methods require dedicated temperature sensors, which increase costs and complexity.
Innovation Solution
A power converter design that includes a cooler, current sensor, and controller, which estimates the temperature of the current sensor using coolant temperature, output current, and input voltage, allowing for thermal protection without a dedicated temperature sensor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a dedicated temperature sensor is installed on the current sensor to measure its temperature directly, then the temperature measurement accuracy is improved, but the device complexity and cost increase
Solution Approach 1:
The patent introduces a bus bar as an intermediary thermal conduction path between the switching element and current sensor. The bus bar conducts heat from the switching element to the current sensor, enabling indirect temperature measurement through the thermal relationship rather than direct contact measurement
Solution Approach 2:
The current sensor itself serves as the measurement target, and its temperature is inferred through its thermal relationship with the switching element. The system uses existing components (switching element, bus bar, coolant) to provide temperature information without requiring the current sensor to be a separate measurement device
2Productivity
If the current sensor is placed close to the switching element to reduce wiring length, then the electrical connection efficiency is improved, but the current sensor is exposed to more heat from the switching element
Solution Approach 1:
The bus bar acts as a thermal intermediary that manages heat transfer from the switching element to the current sensor. By controlling the thermal conduction path through the bus bar and coolant system, the design allows close electrical connection while managing thermal exposure
Solution Approach 2:
The patent uses a coolant system (hydraulic approach) to manage heat transfer. The coolant flows through the bus bar or surrounding structures, actively removing heat from the switching element and reducing thermal exposure to the current sensor while maintaining close electrical connection
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
Accurately estimates the temperature of the current sensor and restricts the load on switching elements to prevent overheating, ensuring reliable power supply to the motor without the need for additional temperature sensors.
Implementation Method 1
The cooler may be configured to cool the switching element
Implementation Method 2
a cooler configured to cool the switching element
Implementation Method 3
Heat of a switching element transfers to a current sensor via a bus bar
Data Source
AI summary
A power converter for an electric vehicle that converts output of a battery to driving an electric traction motor is disclosed. The power converter may include: a power switching element; a current sensor provided on a bus bar in which an output current of the switching element flows; a cooler cooling the switching element; a temperature sensor measuring a temperature of a coolant; and a controller controlling the switching element. The controller may be configured to: estimate a temperature of the current sensor based on the temperature of the coolant; determine a first and second correction values for the estimated temperature based on the output current and an input voltage applied to the switching element; and restrict a load on the switching element when a corrected temperature, which is obtained by adding the first and second correction values to the estimated temperature, exceeds a predetermined temperature threshold.