SiC Switching Element Active Region Heat Generation

Solution Overview

Problem

Vehicle air conditioning systems in electric and hybrid vehicles face challenges in securing a heat source without increasing weight and costs, particularly when frost forms on outside heat exchangers at low temperatures, reducing heating performance.

Innovation Solution

A drive apparatus for switching elements using high-heat resistant semiconductors like silicon carbide, which adjusts driving voltage to operate in an active region for increased heat generation, allowing the generated heat to be used as a heat source, and includes a mode switching unit to optimize between normal and heat generating modes based on temperature and current sensing.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a hot water-refrigerant heat exchanger is used to heat the refrigerant when the outside heat exchanger is frosted, then heating performance is maintained, but the number of components increases leading to increased weight and costs

Engineering Contradiction:

Improveheating performanceVSAvoidsystem weight

Core Design Contradiction:

ReliabilityVSWeight of moving object

Solution Approach 1:

The switching element itself serves as the heat source by operating in the active region to generate heat, eliminating the need for separate heating components like hot water vessels, sheathed heaters, pipes, and pumps. The system uses its own component (switching element) to provide the heating function rather than requiring external auxiliary systems.

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

The switching element performs dual functions: electrical switching for motor control and heat generation for refrigerant heating. By operating in the active region, the switching element simultaneously controls the motor and provides the necessary heat source to prevent frost accumulation, combining multiple functions into a single component.

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Reliability

If a hot water-refrigerant heat exchanger is used to heat the refrigerant when the outside heat exchanger is frosted, then heating performance is maintained, but the number of components increases leading to increased costs

Engineering Contradiction:

Improveheating performanceVSAvoidmanufacturing cost

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The switching element itself serves as the heat source by operating in the active region to generate heat, eliminating the need for separate heating components like hot water vessels, sheathed heaters, pipes, and pumps. The system uses its own component (switching element) to provide the heating function rather than requiring external auxiliary systems.

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

The switching element performs dual functions: electrical switching for motor control and heat generation for refrigerant heating. By operating in the active region, the switching element simultaneously controls the motor and provides the necessary heat source to prevent frost accumulation, combining multiple functions into a single component.

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Loss of energy

If a voltage in the saturation region is applied to the switching element, then switching loss is reduced, but heat generation is insufficient to serve as a heat source

Engineering Contradiction:

Improveswitching lossVSAvoidheat generation

Core Design Contradiction:

Loss of energyVSTemperature

Solution Approach 1:

The driving voltage is dynamically adjusted based on operational requirements. During normal operation, a voltage in the saturation region is applied to minimize switching loss. When heating is required (e.g., during frost conditions), the voltage is adjusted to operate in the active region to increase heat generation. This dynamic adjustment allows the system to optimize between efficiency and heating capability as needed.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The driving voltage parameter is changed from a fixed saturation region voltage to a variable voltage that can operate in either the saturation region or active region. By changing the voltage parameter, the switching element's operating state is adjusted to provide either minimal loss operation or enhanced heat generation, depending on system requirements.

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

This approach secures a heat source while minimizing weight and costs, improving heating performance by utilizing the heat generated by the switching elements in vehicle air conditioning systems.

Implementation Method 1

the voltage adjusting unit applies, as the driving voltage, a voltage in an active region of the transistor to the conduction control terminal... This allows switching loss to be increased... which increases the amount of heat generation

Methodology Applied

Scientific EffectJoule heating: Joule Heating

Data Source

PatentUS10369867B2Apparatus and method for driving a switching element, and a vehicle air-conditioning apparatus

Publication Date: 2019.08.06 MITSUBISHI HEAVY IND THERMAL SYST

AI summary

A drive apparatus providing a heat source and driving a switching element, along with a corresponding method of using the drive apparatus. The switching element includes a transistor having a high-heat resistant semiconductor including silicon carbide. The drive apparatus is provided with a voltage adjusting unit that varies a drive voltage to be applied to a conduction control terminal of the switching element in order to put the switching element in an ON state, and the voltage adjusting unit applies, as the drive voltage, a voltage in an active region of the transistor to the conduction control terminal.