Inductor Temperature Estimation via Voltage-Current Ratio
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In electrified vehicles, the temperature of power converter inductors can rise due to high current flow, leading to potential overheating, which is not effectively managed by traditional direct temperature measurement methods, especially when the battery input voltage remains within a narrow range.
Innovation Solution
A controller adjusts the power limit of the power converter based on the ratio of voltage across the inductor to the rate of change of current, using the monotonic relationship between the initial permeability of the inductor core and temperature, allowing for indirect estimation of temperature without direct measurement, and controlling power through pulse width modulation to prevent overheating.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If direct temperature measurement devices (thermistor) are used to monitor inductor core temperature, then temperature monitoring capability is provided, but device complexity and cost increase
Solution Approach 1:
The inductor core itself serves as the temperature sensing element through its inherent monotonic relationship between initial permeability and temperature. The controller estimates temperature by measuring electrical parameters (voltage and current) and calculating inductance, without requiring external temperature sensors. This self-service approach eliminates additional hardware while providing temperature monitoring capability.
Solution Approach 2:
The patent uses electrical measurements (voltage across inductor and current through inductor) as intermediaries to indirectly determine temperature. By measuring these electrical parameters and calculating inductance, the system obtains temperature information without direct thermal contact or additional sensing hardware.
2Reliability
If power limit is dynamically adjusted based on temperature estimation, then inductor overheating is prevented, but control system complexity increases
Solution Approach 1:
The controller continuously monitors voltage and current measurements, calculates inductance and temperature estimation, and adjusts power limit accordingly. This closed-loop feedback mechanism ensures the inductor operates within safe temperature limits by dynamically modifying power converter limits based on real-time thermal conditions.
Solution Approach 2:
The power limit of the power converter is made dynamic rather than fixed. The controller adjusts the power limit in real-time based on the estimated temperature and operating conditions, allowing the system to optimize performance while preventing overheating. This dynamic adjustment adapts to changing thermal conditions during 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 method effectively prevents inductor overheating by dynamically adjusting power limits based on calculated inductance and temperature correlations, ensuring the inductor operates within safe temperature thresholds without the need for direct temperature sensors.
Implementation Method 1
The inductor may include a core having an initial permeability that is a monotonic function of the temperature of the core
Implementation Method 2
A controller is provided which estimates the temperature of the inductor. The temperature estimation may be based on a correlation between inductance and temperature
Data Source
AI summary
A vehicle includes a power converter having an inductor electrically disposed between a traction battery and an electric machine. The vehicle includes a controller configured to reduce a power limit of the power converter. The reduction is responsive to an increase of a ratio of voltage across the inductor to a rate of change of current through the inductor.