Inverter Mode Switching Adaptation for Voltage Overshoot

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Solution Overview

Problem

In electric vehicle inverters, transient voltage increases and phase overcurrents can occur when switching between operating modes, such as from a clocked to a freewheeling or short-circuit mode, posing safety risks and inefficiencies.

Innovation Solution

A method for switching an inverter that involves determining voltage and current values for the current operating mode, performing an adaptation process to adjust these values for the target mode, and then switching to the target mode, thereby minimizing voltage overshoots and current overloads.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Speed

If the inverter switches directly from a clocked operating mode to a freewheeling or short-circuit mode, then the switching speed is improved, but transient voltage increases and phase overcurrents occur

Engineering Contradiction:
Improveswitching speedVSAvoidtransient voltage increases and phase overcurrents
Core Design Contradiction:
SpeedVSObject-affected harmful factors

Solution Approach 1:

The patent applies preliminary action by performing an adaptation process before the actual mode switching occurs. The controller determines voltage and current values for the current operating mode, then carries out an adaptation process to adjust these values for the target operating mode. This preparatory adjustment of voltage and current parameters prevents transient voltage increases and phase overcurrents when switching from clocked mode to freewheeling or short-circuit mode, while still achieving fast switching within milliseconds.

Inventive Principle:
Principle #10Preliminary action

2Reliability

If the inverter operates in unclocked modes (freewheeling or active short-circuit) to ensure safety, then the safety state is improved, but the productivity is reduced due to inability to generate torque

Engineering Contradiction:
Improvesafety stateVSAvoidtorque generation capability
Core Design Contradiction:
ReliabilityVSProductivity

Solution Approach 1:

The patent applies dynamics by enabling the inverter to dynamically switch between different operating modes (clocked, freewheeling, and short-circuit modes) based on real-time operational requirements. The controller can quickly transition between modes that generate torque and modes that ensure safety, optimizing both productivity and reliability. The adaptation process ensures smooth transitions while maintaining the ability to generate torque when needed and ensuring safety when required.

Inventive Principle:
Principle #15Dynamics

3Stability of the object's composition

If an adaptation process is carried out to adjust voltage and current values, then the stability is improved, but the switching time is extended

Engineering Contradiction:
Improveoperational stabilityVSAvoidswitching time
Core Design Contradiction:
Stability of the object's compositionVSLoss of time

Solution Approach 1:

The patent applies parameter changes by adjusting voltage and current parameters during the adaptation process. The controller determines the voltage and current values for the current operating mode, then modifies these parameters to match the target operating mode requirements. This controlled parameter adjustment ensures stable transitions between operating modes while keeping the adaptation process brief, achieving both operational stability and acceptable switching time within milliseconds.

Inventive Principle:
Principle #35Parameter changes

Data Source

PatentEP3145750B1Method for switching an inverter of an electric drive of a motor vehicle and a correspondingly switchable inverter
Publication Date: 2021.05.12 VOLKSWAGEN AG
  • EP3145750B1 patent drawingFigure 1~2
  • EP3145750B1 patent drawingFigure 3
  • EP3145750B1 patent drawingFigure 3

AI summary

The present invention relates to a method (1) for switching an inverter of an electrical drive of a motor vehicle, wherein the inverter has at least one free-running operating mode (303), a short-circuit operating mode (305) and a clocked operating mode (301), in which a DC voltage is converted to AC voltage and vice versa, wherein the method (1) for switching the inverter from a current operating mode to a target operating mode that is different to the current operating mode comprises: determination (101) of a voltage value and/or a current value for the current operating mode; performance (103) of an adaptation procedure according to the determined voltage value and/or the determined current value in order to adapt the voltage and/or the current for the target operating mode; and switching (105) to the target operating mode.