Inverter Semiconductor Switch Control for Rapid Discharge

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Solution Overview

Problem

Existing control systems for semiconductor switches in inverters require additional components and increased circuit complexity to achieve rapid or emergency discharge, which is costly and space-intensive, and may lead to overheating during the discharge process.

Innovation Solution

A control device that utilizes the existing semiconductor switches in an inverter to implement a pulsed drive signal with short pulse lengths, allowing the switches to be briefly in a transitional state between blocking and conducting, effectively converting energy from the intermediate circuit capacitor into heat for quick and reliable discharge without additional components.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If additional components are added to achieve rapid discharge, then discharge reliability is improved, but device complexity and installation space increase

Engineering Contradiction:
Improvedischarge reliabilityVSAvoidcircuit complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The semiconductor switches in the inverter are made to serve dual functions: normal inverter operation and rapid discharge of the intermediate circuit capacitor. By controlling the semiconductor switches to operate in a linear region with short pulse durations, the existing components perform the discharge function without requiring dedicated discharge circuitry, thereby maintaining reliability while reducing device complexity.

Inventive Principle:
Principle #6Universality (Multi-functionality)

Solution Approach 2:

The inverter's existing semiconductor switches and thermal management system are utilized to perform the rapid discharge function. The semiconductor switches convert capacitor energy to heat during brief conduction periods, and the existing cooling system dissipates this heat, making the system self-sufficient for discharge operations without external components.

Inventive Principle:
Principle #25Self-service

2Speed

If additional components are added to achieve rapid discharge, then discharge speed is improved, but installation space increases

Engineering Contradiction:
Improvedischarge speedVSAvoidinstallation space
Core Design Contradiction:
SpeedVSArea of stationary object

Solution Approach 1:

The same semiconductor switches and physical space are used for both normal inverter operation and rapid discharge operations. The semiconductor switches are controlled to operate in a linear region with short pulses, enabling the intermediate circuit capacitor to discharge rapidly through the existing circuit path without requiring additional space for discharge components.

Inventive Principle:
Principle #6Universality (Multi-functionality)

3Reliability

If semiconductor switches are driven with long pulses to fully conduct, then switching reliability is improved, but energy conversion to heat increases causing overheating

Engineering Contradiction:
Improveswitching reliabilityVSAvoidswitch temperature
Core Design Contradiction:
ReliabilityVSTemperature

Solution Approach 1:

Instead of continuous conduction, the semiconductor switches are driven with periodic short pulses during the rapid discharge operation. This pulsed operation allows the switches to convert capacitor energy to heat in brief intervals, followed by cooling periods where the existing thermal management system can dissipate heat, preventing overheating while maintaining reliable discharge function.

Inventive Principle:
Principle #19Periodic action

Solution Approach 2:

The semiconductor switches are operated in a linear region with partial conduction rather than full saturation. By applying short control pulses that keep the switches in a transitional state, sufficient current flows to discharge the capacitor rapidly, but the brief duration limits total energy conversion to heat, preventing overheating while achieving the discharge function.

Inventive Principle:
Principle #16Partial or excessive action

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 solution enables rapid and reliable discharge of the intermediate circuit capacitor without additional components, reducing costs and installation space, while maintaining thermal connectivity to prevent overheating, thus ensuring efficient and safe energy dissipation.

Implementation Method 1

energy from the intermediate circuit capacitor can be converted into heat when a current flows through the respective semiconductor switches

Methodology Applied
Scientific EffectJoule heating: Joule Heating

Data Source

PatentEP2794334B1Control device for semiconductor switch on an inverter and method for the actuation of an inverter
Publication Date: 2018.08.29 ROBERT BOSCH GMBH
  • EP2794334B1 patent drawingFigure 1~3
  • EP2794334B1 patent drawingFigure 4~8

AI summary

The invention relates to a control device (4) for the actuation of a semiconductor switch (1) on an inverter having an actuation switch (16) that is designed to generate a driver signal (18) depending on a switch signal (5) generated by a control regulation of the inverter, and a driver circuit (15) that is connected between the actuation circuit (16) and a control input (13) of the semiconductor switch (1), and which is designed to receive the driver signal (18) and a control signal (7) depending on the driver signal (18), said control signal actuating a semiconductor switch (1) for the generation and infeed into the control input (13) of the semiconductor switch (1), wherein the actuation circuit (16) is designed to generate the driver signal (18) as a consequence of driver signal pulses with a predetermined and adjustable pulse length such that the semiconductor switch (1) is not fully conductive in the event of an actuation with the control signal (7) during the pulse length.