Motor Control Device Safety Shutdown via Segmented Driver

Solution Overview

Problem

Existing control devices for electric motors lack the capability to safely and reliably achieve a torque-free state, particularly in field-weakened motors, without risking damage from excess voltage or unacceptably large torque generation.

Innovation Solution

A control device comprising a motor control unit, a safety unit, and a driver unit that generates power semiconductor control signals to manage power semiconductors in bridge branches, allowing for independent torque-free or torque-reduced states through distinct safety control signal patterns, ensuring safe operation and redundancy in voltage supply and sensor monitoring.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If the control device uses a single control unit for both motor control and safety functions, then device complexity is reduced, but safety reliability deteriorates due to potential interference between control signals

Engineering Contradiction:

Improvecontrol device complexityVSAvoidsafety reliability

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

The control device is segmented into distinct functional units: a motor control unit for generating motor control signals and a separate safety unit for generating safety control signals. This segmentation ensures that safety functions are independent from motor control functions, preventing signal interference and ensuring reliable torque-free state achievement even when the motor control unit generates torque-producing signals.

Inventive Principle:

Principle #1Segmentation

2Reliability

If the safety unit overrides motor control signals to achieve torque-free state, then safety reliability is improved, but device complexity increases due to multiple control units and signal patterns

Engineering Contradiction:

Improvesafety reliabilityVSAvoidcontrol device complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The control device is segmented into distinct functional units: a motor control unit for generating motor control signals and a separate safety unit for generating safety control signals. This segmentation ensures that safety functions are independent from motor control functions, preventing signal interference and ensuring reliable torque-free state achievement even when the motor control unit generates torque-producing signals.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The safety unit achieves torque-free state by changing the state parameters of power semiconductors from conductive to non-conductive through safety control signals. By controlling the electrical state (conductive/non-conductive) of power semiconductors, the system can reliably eliminate torque generation without complex mechanical intervention.

Inventive Principle:

Principle #35Parameter changes

3Reliability

If all power semiconductors are switched off to achieve torque-free state, then safety is improved, but intermediate circuit voltage may become excessive causing damage

Engineering Contradiction:

Improvesafety reliabilityVSAvoidintermediate circuit excess voltage

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The safety unit achieves torque-free state by changing the state parameters of power semiconductors from conductive to non-conductive through safety control signals. By controlling the electrical state (conductive/non-conductive) of power semiconductors, the system can reliably eliminate torque generation even during field-weakening operation without causing intermediate circuit voltage to become excessive.

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentUS10530147B2Control device with safety shutdown

Publication Date: 2020.01.07 BUCHER HYDRAULICS AG

AI summary

A control device for an electrical device such as an electric motor is provided. The control device is designed to, when necessary, bring about a safe, torque-free state of an electric motor, in particular a field-weakened electric motor. The control device includes a safety unit which is designed to generate safety control signals. A driver unit of the control device is designed to generate, irrespective of a state of motor control signals, in the case of a first state pattern of the safety control signals, power semiconductor control signals in such a way that power semiconductors have a non-conductive state, in the case of a second state pattern of the safety control signals to generate the power semiconductor control signals in such a way that a bridge output terminal is electrically connected to a positive intermediate circuit potential, and in the case of a third state pattern of the safety control signals to generate the power semiconductor control signals in such a way that the bridge output terminal is electrically connected to a negative intermediate circuit potential.