Contactor Clamp Switching for Quick Turn-Off Without Supply Voltage

Solution Overview

Problem

Conventional high-voltage contactor systems struggle to execute quick-turn-off (QTO) during power loss, as the lack of sufficient supply voltage results in slower current decay, potentially causing system damage due to inadequate reverse polarity voltage across the coil.

Innovation Solution

The system detects a low supply voltage and disables the high-side clamp, generating a current for the low-side clamp using the output voltage to enable quick-turn-off, ensuring safe and reliable QTO by adjusting the QTO voltage through a voltage detection and comparison circuit.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional HS and LS clamps are used with supply voltage for QTO, then QTO can be executed when power is on, but QTO fails when power goes off due to insufficient supply voltage

Engineering Contradiction:

ImproveQTO execution reliabilityVSAvoidQTO capability under power-off condition

Core Design Contradiction:

ReliabilityVSAdaptability or versatility

Solution Approach 1:

The patent introduces an intermediary voltage selection mechanism that switches between supply voltage (when available) and output voltage (when supply voltage is insufficient). This mediator enables the clamp circuit to function under both powered-on and powered-off conditions, resolving the contradiction between reliability during normal operation and adaptability during power loss.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The system dynamically selects the voltage source based on the availability of supply voltage. The clamp circuit transitions from using supply voltage during normal operation to using output voltage during power-off conditions. This dynamic adaptation ensures QTO reliability across varying operational states, addressing both reliability and adaptability requirements.

Inventive Principle:

Principle #15Dynamics

2Speed

If high reverse polarity voltage is generated across the coil for fast current decay, then QTO speed is improved, but the clamp voltage may exceed maximum clamp voltage determined by transistor breakdown characteristics

Engineering Contradiction:

ImproveCurrent decay rateVSAvoidTransistor breakdown resistance

Core Design Contradiction:

SpeedVSStrength

Solution Approach 1:

The patent changes the voltage parameter dynamically by selecting between supply voltage and output voltage based on operational conditions. This parameter adjustment allows the system to achieve high reverse polarity voltage when needed while respecting the maximum clamp voltage limit imposed by transistor breakdown characteristics, thus balancing speed and strength requirements.

Inventive Principle:

Principle #35Parameter changes

3Power

If supply voltage is used to generate clamp current for QTO, then QTO can be executed under normal conditions, but clamp current becomes very low when supply voltage drops below threshold

Engineering Contradiction:

ImproveClamp current generation capabilityVSAvoidQTO execution under low voltage

Core Design Contradiction:

PowerVSReliability

Solution Approach 1:

The patent introduces an intermediary voltage selection mechanism that switches between supply voltage (when available) and output voltage (when supply voltage is insufficient). This mediator enables the clamp circuit to function under both powered-on and powered-off conditions, resolving the contradiction between reliability during normal operation and adaptability during power loss.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The system dynamically selects the voltage source based on the availability of supply voltage. The clamp circuit transitions from using supply voltage during normal operation to using output voltage during power-off conditions. This dynamic adaptation ensures QTO reliability across varying operational states, addressing both reliability and adaptability requirements.

Inventive Principle:

Principle #15Dynamics

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 approach allows for safe and reliable QTO even without sufficient supply voltage, preventing system damage by maintaining the desired current decay rate and not interfering with normal QTO operations when power is available.

Implementation Method 1

a coil to generate a magnetic force to mechanically operate an electric contact (or armature)

Methodology Applied

Scientific EffectElectromagnetic induction: Electromagnetic Induction

Implementation Method 2

a high, reverse polarity voltage, greater than the supply voltage, be generated across the coil (load)

Methodology Applied

Scientific EffectElectrical conduction: Conduction (electrical)

Data Source

PatentUS12179617B2Quick turn off of contactor system during power off

Publication Date: 2024.12.31 TEXAS INSTRUMENTS INC

AI summary

Examples of contactor controllers, systems and methods enable quick-turn-off (QTO) using an output voltage of a contactor controller when its supply voltage is below a threshold but does not interfere with QTO when sufficient supply voltage is available. In an example, when VM loss occurs, a high-side (HS) clamp of a contactor controller is disabled, and a low-side (LS) clamp current is generated using the output voltage. The LS clamp current may be adjusted to achieve a desired QTO voltage. In another example, a HS clamp is disabled and the charging of the gate of a LS field-effect transistor (FET) is enabled only when the output voltage increases above a power-off QTO threshold (less than the LS clamp voltage); the QTO voltage is set by a voltage detection and comparison circuit of the contactor controller.