Inductor Temperature Modeling for DC/DC Converter Overheating

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Solution Overview

Problem

Inductors in DC/DC converters of electric drive systems generate excessive heat due to high current ratings and reduced battery voltages, leading to temperature exceedance, which is difficult to measure accurately and requires protective measures.

Innovation Solution

A dynamic model is used to estimate inductor temperature based on easily measurable parameters like coolant pump speed, motor speed, and coolant sump temperature, allowing for torque and voltage adjustments to prevent overheating.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Power

If the inductor current rating is increased to handle higher power, then the power handling capability is improved, but the inductor temperature increases excessively

Engineering Contradiction:

Improvepower handling capabilityVSAvoidinductor temperature

Core Design Contradiction:

PowerVSTemperature

Solution Approach 1:

The system performs preliminary cooling actions by activating the coolant pump and adjusting coolant flow before the inductor temperature reaches critical levels. The controller predicts temperature trends and initiates cooling measures proactively based on current operating conditions and historical data, preventing excessive temperature rise before it occurs.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system implements feedback control by continuously monitoring inductor temperature, coolant temperature, and pump speed, then adjusting the coolant pump speed and cooling system operation accordingly. The controller modifies cooling intensity based on real-time temperature measurements and predicted temperature changes, creating a closed-loop control system that maintains temperature within acceptable ranges.

Inventive Principle:

Principle #23Feedback

2Reliability

If the inductor temperature is monitored continuously to prevent overheating, then the operational safety is improved, but the measurement accuracy is difficult to achieve

Engineering Contradiction:

Improveoperational safetyVSAvoidtemperature measurement accuracy

Core Design Contradiction:

ReliabilityVSMeasurement precision

Solution Approach 1:

The system uses coolant temperature sensors as intermediary measurement points to indirectly assess inductor temperature. By monitoring the temperature of the coolant passing through or near the inductor, the system obtains reliable temperature data without requiring direct contact with the high-current inductor environment, which would be difficult and unsafe for direct measurement.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The system replaces direct physical temperature measurement of the inductor with a mathematical model that predicts inductor temperature based on measurable parameters such as coolant temperature, pump speed, and operating conditions. This computational approach substitutes direct measurement with indirect calculation, achieving accurate temperature assessment without the measurement challenges of direct contact.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Temperature

If the motor operating envelope is restricted to maintain inductor temperature limits, then the temperature control is improved, but the productivity is reduced

Engineering Contradiction:

Improveinductor temperature controlVSAvoidmotor operating capability

Core Design Contradiction:

TemperatureVSProductivity

Solution Approach 1:

The system implements dynamic temperature management by continuously adjusting the coolant pump speed and cooling intensity based on real-time operating conditions and predicted temperature trends. Rather than applying fixed restrictions, the system dynamically modifies cooling capacity to match actual thermal conditions, allowing maximum motor performance when temperatures are acceptable and applying restrictions only when necessary.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The system changes operating parameters such as coolant flow rate, pump speed, and cooling intensity to manage inductor temperature. By adjusting these parameters dynamically, the system maintains temperature within limits while minimizing impact on motor performance, allowing the motor to operate at full capability when thermal conditions permit.

Inventive Principle:

Principle #35Parameter changes

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 predicts inductor temperature, enabling proactive control to prevent overheating and maintain operational safety within design limits.

Implementation Method 1

Inductors in DC/DC converters of electric drive systems generate excessive heat due to high current ratings

Methodology Applied

Scientific EffectJoule heating: Joule Heating

Implementation Method 2

The inductor may be cooled by various mechanisms

Methodology Applied

Scientific EffectConvection cooling: Convection

Data Source

PatentUS12424964B2Dynamic models for inductor temperature

Publication Date: 2025.09.23 FORD GLOBAL TECH LLC

AI summary

An electric drive system includes an inverter and a variable voltage converter. An inductor associated with the variable voltage converter is subject to temperature limits. Dynamic models are used to estimate the temperature of the inductor. Inputs to these dynamics models include DC current, DC voltage, Battery Voltage, oil pump speed, motor speed, and sump temperature. Empirical constants in the models are set based on vehicle testing.