Permanent Magnet Machine Braking Control for Short-Circuit Faults

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Solution Overview

Problem

Permanent magnet machines are prone to short circuit failures in their windings, leading to high currents and temperatures that can cause detrimental system effects, necessitating rapid and effective response mechanisms to minimize damage.

Innovation Solution

A controller is configured to detect short circuit failures and transition the machine into a braking mode, drawing energy to decelerate the machine, using healthy windings to generate negative torque, and managing current demand through controlled stages to reduce the risk of damage.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a short circuit failure occurs in the windings, then high currents flow causing high temperatures, but this leads to detrimental system effects and potential machine damage

Engineering Contradiction:

Improvemachine protectionVSAvoidhigh current and temperature damage

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The controller is pre-configured with a braking mode that can be immediately activated upon detecting a short circuit failure. Healthy windings are pre-arranged to generate negative torque, enabling rapid response without requiring complex real-time decision algorithms, thus minimizing damage exposure time

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The invention converts the harmful high current condition into a beneficial braking force. By controlling the inverter to draw energy from the machine during a short circuit event, the abnormal current flow is transformed into negative torque that decelerates the machine, protecting it from damage while utilizing the available energy

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

2Loss of time

If the machine is immediately stopped upon short circuit detection, then damage time is reduced, but this requires rapid response capability that may not be achievable with conventional control methods

Engineering Contradiction:

Improvehigh current exposure timeVSAvoidrapid response implementation

Core Design Contradiction:

Loss of timeVSEase of operation

Solution Approach 1:

The braking mode is pre-programmed in the controller with defined current demand stages. Upon short circuit detection, the controller simply activates this pre-prepared sequence, eliminating the need for complex real-time calculations and enabling rapid response within milliseconds

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The controller dynamically adjusts current demand through three distinct stages (reduction, stationary, increase) based on machine speed and conditions. This dynamic adaptation allows the system to achieve rapid deceleration while maintaining operational feasibility and avoiding excessive stress on the system

Inventive Principle:

Principle #15Dynamics

3Force

If high current is drawn to generate negative torque for braking, then deceleration is achieved, but this may cause current spikes that could damage healthy windings

Engineering Contradiction:

Improvenegative torque for decelerationVSAvoidcurrent spikes in healthy windings

Core Design Contradiction:

ForceVSObject-affected harmful factors

Solution Approach 1:

The controller implements dynamic current demand adjustment through three staged phases. The current demand is modified based on real-time machine speed and operational conditions, allowing the system to generate sufficient negative torque for effective braking while preventing excessive current spikes that could damage healthy windings

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The controller changes the current demand parameter adaptively during the braking process. By adjusting the magnitude and duration of current draw based on machine state, the system optimizes the balance between generating adequate braking force and protecting healthy windings from damaging current spikes

Inventive Principle:

Principle #35Parameter changes

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

The braking mode minimizes damage by reducing the time of high current and temperature exposure, using controlled current demand transitions to safely decelerate the machine.

Implementation Method 1

The machine has a stator with stator windings that are distributed to wrap around one or more stator teeth. A rotating field is generated by the stator windings.

Methodology Applied

Scientific EffectElectromagnetic induction: Electromagnetic Induction

Implementation Method 2

In the braking mode, energy is drawn from the permanent magnet machine in order to decelerate the permanent magnet machine

Methodology Applied

Scientific EffectElectromagnetic induction: Electromagnetic Induction

Data Source

PatentUS20260012113A1Controller for a permanent magnet machine

Publication Date: 2026.01.08 HAMILTON SUNDSTRAND CORP

AI summary

A controller for a drive system, the drive system comprising a permanent magnet machine, wherein the controller is configured to receive a short circuit signal indicating that a short circuit failure has been detected in the drive system and in response to receiving the short circuit signal, control the permanent magnet machine into a braking mode, wherein in the braking mode, energy is drawn from the permanent magnet machine in order to decelerate the permanent magnet machine.