DC-DC Converter Over-Temperature Protection via Dual-Sensor Frequency Control

Solution Overview

Problem

Existing DC-DC converters face challenges in preventing overheating of capacitors and reactors due to opposite temperature increase characteristics with respect to switching frequency changes, leading to increased risk of overheating despite efforts to manage switching element temperature.

Innovation Solution

A voltage conversion device with a cooling unit and temperature detection system that adjusts the switching frequency of the switching element based on both the switching element and cooling medium temperatures, and controls the voltage conversion ratio or prohibits switching operations to manage overheating of capacitors and reactors.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Temperature

If the switching frequency of the switching element is reduced to suppress temperature increase of the switching element, then the switching element overheating is suppressed, but the ripple component of the current flowing through the reactor is increased, causing the reactor to overheat

Engineering Contradiction:

Improveswitching element temperatureVSAvoidreactor temperature

Core Design Contradiction:

TemperatureVSTemperature

Solution Approach 1:

The patent applies parameter changes by dynamically adjusting the switching frequency based on the detected temperature of the switching element. When the switching element temperature exceeds a threshold, the control unit reduces the switching frequency to suppress further temperature increase, preventing switching element overheating while managing the trade-off with reactor ripple current.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent implements feedback control by using a temperature detection unit to continuously monitor the switching element temperature and feed this information back to the control unit. The control unit then adjusts the switching frequency accordingly, creating a closed-loop control system that prevents switching element overheating while managing reactor temperature through frequency modulation.

Inventive Principle:

Principle #23Feedback

2Temperature

If the switching frequency of the switching element is reduced to suppress temperature increase of the switching element, then the switching element overheating is suppressed, but the ripple current flowing through the filtering capacitor is increased, causing the filtering capacitor to overheat

Engineering Contradiction:

Improveswitching element temperatureVSAvoidfiltering capacitor temperature

Core Design Contradiction:

TemperatureVSTemperature

Solution Approach 1:

The patent applies parameter changes by dynamically adjusting the switching frequency based on the detected temperature of the switching element. When the switching element temperature exceeds a threshold, the control unit reduces the switching frequency to suppress further temperature increase, preventing switching element overheating while managing the trade-off with filtering capacitor ripple current.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent implements feedback control by using a temperature detection unit to continuously monitor the switching element temperature and feed this information back to the control unit. The control unit then adjusts the switching frequency accordingly, creating a closed-loop control system that prevents switching element overheating while managing filtering capacitor temperature through frequency modulation.

Inventive Principle:

Principle #23Feedback

3Temperature

If the switching frequency is increased to reduce ripple current, then the ripple component is reduced, but the amount of generated heat in the switching element is increased

Engineering Contradiction:

Improvereactor temperatureVSAvoidswitching element temperature

Core Design Contradiction:

TemperatureVSTemperature

Solution Approach 1:

The patent applies parameter changes by dynamically adjusting the switching frequency based on real-time temperature detection. The control unit increases switching frequency to reduce ripple current and reactor temperature, while monitoring switching element temperature to prevent excessive heat generation, thereby optimizing the frequency parameter to balance both temperature concerns.

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

Effectively prevents overheating of capacitors and reactors by managing switching frequency and voltage conversion ratio based on cooling medium and switching element temperatures, reducing the risk of overheating without directly detecting reactor and capacitor temperatures.

Implementation Method 1

a cooling unit which cools the DC-DC converter with a cooling medium

Methodology Applied

Scientific EffectHeat transfer: Conduction (thermal)

Implementation Method 2

a temperature detection system that adjusts the switching frequency of the switching element based on both the switching element and cooling medium temperatures

Methodology Applied

Scientific EffectTemperature detection: Thermocouple

Data Source

PatentEP2184840B1Over temperature protection for voltage converter

Publication Date: 2017.03.08 TOYOTA JIDOSHA KK

AI summary

A switching frequency setting section sets switching frequency of a switching element, based on both the temperature of a cooling medium which cools a DC-DC converter and the temperature of a switching element of the DC-DC converter. A switching control section controls the voltage conversion ratio of the DC-DC converter by controlling switching operation of the switching element at the set switching frequency.