Bidirectional Switch Inverter for Motor Drive Stability

Solution Overview

Problem

Existing motor drive apparatuses for rotating electric machines face instability and increased conduction loss due to regenerative current when switching between low-speed and high-speed operations, particularly in electric vehicles, where additional disconnect switches increase electrical resistance and heat generation.

Innovation Solution

The implementation of a drive apparatus with bidirectionally-conducting and bidirectionally-blocking upper-arm and lower-arm switches in the first inverter, which function as flyback diodes, allows for regenerative current prevention without additional switches, minimizing conduction loss and enabling efficient energization control across varying operational speeds.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If disconnect switches are added to prevent regenerative current, then motor operation stability is improved, but conduction loss increases due to additional electrical resistance

Engineering Contradiction:

Improvemotor operation stabilityVSAvoidconduction loss

Core Design Contradiction:

ReliabilityVSLoss of energy

Solution Approach 1:

The upper-arm and lower-arm switches in the first inverter are configured to have bidirectionally-conducting and bidirectionally-blocking functions, enabling them to automatically prevent regenerative current flow without requiring additional disconnect switches. This self-service capability eliminates the need for extra components while maintaining motor operation stability.

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

The upper-arm and lower-arm switches are designed to perform multiple functions: normal switching operations and bidirectional blocking of regenerative current. This multi-functionality allows the existing switches to serve as both power switches and regenerative current barriers, eliminating the need for separate disconnect switches and reducing overall conduction loss.

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Reliability

If disconnect switches are added to prevent regenerative current, then regenerative current is blocked, but device complexity increases

Engineering Contradiction:

Improveregenerative current preventionVSAvoidnumber of switches

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The upper-arm and lower-arm switches are designed to perform multiple functions: normal switching operations and bidirectional blocking of regenerative current. This multi-functionality allows the existing switches to serve as both power switches and regenerative current barriers, eliminating the need for separate disconnect switches and reducing overall conduction loss.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The upper-arm and lower-arm switches in the first inverter are configured to have bidirectionally-conducting and bidirectionally-blocking functions, enabling them to automatically prevent regenerative current flow without requiring additional disconnect switches. This self-service capability eliminates the need for extra components while maintaining motor operation stability.

Inventive Principle:

Principle #25Self-service

3Reliability

If additional disconnect switches are added, then regenerative current path is interrupted, but heat generation increases

Engineering Contradiction:

Improveregenerative current interruptionVSAvoidheat generation

Core Design Contradiction:

ReliabilityVSTemperature

Solution Approach 1:

The upper-arm and lower-arm switches in the first inverter are configured to have bidirectionally-conducting and bidirectionally-blocking functions, enabling them to automatically prevent regenerative current flow without requiring additional disconnect switches. This self-service capability eliminates the need for extra components while maintaining motor operation stability.

Inventive Principle:

Principle #25Self-service

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 configuration prevents regenerative current flow through the first inverter, maintains low conduction loss, and allows for smooth switching between drive modes, enhancing the power performance and reliability of electric vehicles by reducing heat generation and improving fuel efficiency.

Implementation Method 1

each of the upper-arm and lower-arm switches of the first inverter is configured to have bidirectionally-conducting and bidirectionally-blocking functions

Methodology Applied

Scientific EffectBidirectional blocking function:

Data Source

PatentUS11228270B2Drive apparatus for rotating electric machine

Publication Date: 2022.01.18 DENSO CORP

AI summary

A drive apparatus is provided for driving a multi-phase rotating electric machine. The rotating electric machine includes a plurality of winding groups for respective phases. The drive apparatus includes a first inverter connected with start terminals of the winding groups of the rotating electric machine, a second inverter connected with intermediate terminals of the winding groups, and an energization controller configured to selectively perform energization of the winding groups by the first inverter and energization of the winding groups by the second inverter. Each of the first and second inverters includes a plurality of switch pairs respectively corresponding to the winding groups and each consisting of an upper-arm switch and a lower-arm switch that are connected in series with each other. Moreover, each of the upper-arm and lower-arm switches of the first inverter is configured to have bidirectionally-conducting and bidirectionally-blocking functions.