Brushless Synchronous Machine Field Voltage Limiter

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Solution Overview

Problem

In brushless synchronous machines, the difficulty in measuring main field voltage due to rotation makes it challenging to detect faults in the feedback loop or system, leading to potential overexceeding of field current and main field voltage beyond rated values.

Innovation Solution

A limiter is introduced that uses a transfer function to estimate main field voltage based on field current, limiting the field current to maintain the main field voltage within specified limits, preventing excessive values.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If a feedback loop is used to control field current, then the main field voltage can be regulated, but the main field voltage cannot be conveniently measured due to rotation of the field

Engineering Contradiction:

Improvemain field voltage measurementVSAvoidconvenience of measurement

Core Design Contradiction:

Measurement precisionVSEase of operation

Solution Approach 1:

The patent introduces an intermediary measurement approach by measuring the field current through the regulator (stationary component) instead of directly measuring the rotating main field voltage. The field current serves as a mediator that can be conveniently measured and used to infer the main field voltage status, resolving the measurement difficulty caused by field rotation.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If the field current is controlled by feedback loop, then the main field voltage can be regulated, but faults in the feedback loop or system may cause the field current and main field voltage to exceed rated values

Engineering Contradiction:

Improvefeedback loop controlVSAvoidoverexceeding of field current and main field voltage

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent implements a preliminary protective action by establishing a limiter that sets a maximum allowable field current threshold before faults can cause dangerous overexceeding. This preventive mechanism is configured in advance to intercept and limit abnormal field current increases, protecting the system from harmful effects before they occur.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent enhances the existing feedback loop by adding a limiter component that provides an additional feedback mechanism. The limiter continuously monitors the field current and provides corrective feedback by clamping the current at the rated maximum value, creating a dual-feedback system that improves reliability and prevents harmful overexceeding.

Inventive Principle:

Principle #23Feedback

3Adaptability or versatility

If no limiter is introduced, then the feedback loop can operate freely, but the main field voltage may exceed rated values due to undetected faults

Engineering Contradiction:

Improvefeedback loop operation freedomVSAvoidmain field voltage within rated values

Core Design Contradiction:

Adaptability or versatilityVSManufacturing precision

Solution Approach 1:

The limiter acts as an intermediary protective device between the feedback loop and the field current. It mediates the conflict between free feedback operation and voltage precision by allowing the feedback loop to operate freely while simultaneously ensuring that the field current does not exceed rated values, thus maintaining manufacturing precision.

Inventive Principle:

Principle #24Intermediary (Mediator)

Data Source

PatentEP2950442B1Main field voltage limiter in brushless synchronous machines

Publication Date: 2020.12.09 GENERAL ELECTRIC CO

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AI summary

A brushless synchronous machine with a limiter (310) for main field voltage and a method of limiting main field voltage in a brushless synchronous machine are described. The machine includes a regulator (140) to use a field current (110) to excite main field windings and generate the main field voltage. The machine also includes a limiter (310) to limit the field current (110) to maintain the main field voltage corresponding to the field current (110) below a limit based on a transfer function.