AC Rotary Machine Control Apparatus Inversion Strategy

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Solution Overview

Problem

Existing control apparatuses for AC rotary machines in electric vehicles face a continuous short-circuit issue in the DC power source when switching elements in both the upper and lower arms are simultaneously turned ON during a three-phase short circuit, leading to overvoltage suppression failures.

Innovation Solution

A control apparatus with an abnormality detection device that turns OFF all switching elements in one arm and reverses the ON/OFF state of the other arm when a short circuit is detected, preventing continuous short-circuiting by intermittently controlling the switching elements and reversing their operation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If all switching elements in the upper arm or lower arm are turned ON to suppress overvoltage, then overvoltage is suppressed, but continuous short-circuit of the DC power source occurs when switching elements in both arms are simultaneously ON

Engineering Contradiction:

Improveovervoltage suppressionVSAvoidcontinuous short-circuit of DC power source

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

When overvoltage suppression is needed, instead of turning ON all switching elements in one arm (which may cause continuous short-circuit), the invention turns OFF all switching elements in one arm and turns ON all switching elements in the other arm. This inverted approach achieves the same overvoltage suppression effect while avoiding the harmful continuous short-circuit condition by ensuring that switching elements in both arms are never simultaneously ON.

Inventive Principle:

Principle #13The other way round (Inversion)

2Object-affected harmful factors

If switching elements in one arm are turned OFF and the other arm's switching elements are turned ON, then continuous short-circuit is prevented, but overvoltage suppression effectiveness may be reduced

Engineering Contradiction:

Improvecontinuous short-circuit preventionVSAvoidovervoltage suppression effectiveness

Core Design Contradiction:

Object-affected harmful factorsVSReliability

Solution Approach 1:

The invention inverts the conventional approach by turning OFF switching elements in one arm and turning ON switching elements in the other arm, rather than turning ON all switching elements in one arm. This inversion simultaneously achieves continuous short-circuit prevention and maintains overvoltage suppression effectiveness by creating a three-phase short circuit state through the complementary switching pattern.

Inventive Principle:

Principle #13The other way round (Inversion)

Data Source

PatentUS10014815B2Control apparatus and control method of AC rotary machine

Publication Date: 2018.07.03 MITSUBISHI ELECTRIC MOBILITY CORP

AI summary

When an abnormality is detected by an abnormality detection unit, a first switching stop device turns OFF all of switching elements connected to one arm of either an upper arm or a lower arm of a power converter, and turns ON all of the switching elements connected to the arm, which are not turned OFF; when the abnormality is continuously detected even after operating the first switching stop device, a second switching stop device turns ON or turns OFF the switching elements connected to the upper arm and the lower arm so that the turn-ON and the turn-OFF are reversed to the operation by the first switching stop device; and when the abnormality is continuously detected even after operating the second switching stop device, a third switching stop device turns OFF all of the switching elements in the upper arm and the lower arm.