Bistable Relay Circuit Voltage Regulation

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Solution Overview

Problem

Existing circuit arrangements for driving bistable relays require high-capacity capacitors or high supply voltages to ensure minimum voltage at the relay coil, which can lead to reduced service life and increased costs due to the need for larger capacitors or elevated initial voltages.

Innovation Solution

Incorporating a voltage regulator to limit the voltage applied to the relay coil, preventing excessive voltage levels and allowing for a smaller capacitor to be used, with the regulator ensuring a longer current surge duration and protecting the relay coil from damage.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a capacitor with larger capacitance is used to ensure minimum voltage at the relay coil, then the voltage remains sufficiently high during switching time, but the space and cost increase

Engineering Contradiction:
Improvevoltage stability at relay coilVSAvoidcapacitor size
Core Design Contradiction:
ReliabilityVSVolume of moving object

Solution Approach 1:

The patent changes the voltage parameter by introducing a voltage regulator that actively maintains the supply voltage at a predetermined level. This allows the use of a smaller capacitor because the voltage regulator compensates for voltage drops during switching operations, ensuring the relay coil receives sufficient voltage without requiring a large energy-storing capacitor.

Inventive Principle:
Principle #35Parameter changes

2Reliability

If the supply voltage is increased to ensure minimum voltage at the relay coil, then the voltage remains sufficiently high during switching time, but the relay coil may be damaged by excessive voltage

Engineering Contradiction:
Improvevoltage stability at relay coilVSAvoidovervoltage damage to relay coil
Core Design Contradiction:
ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The voltage regulator implements a feedback mechanism that continuously monitors the voltage at the relay coil and adjusts the output accordingly. When voltage drops during switching operations, the regulator increases output to maintain the predetermined voltage level. When voltage would otherwise exceed safe levels, the regulator reduces output, thus protecting the relay coil from overvoltage damage while ensuring adequate voltage during switching.

Inventive Principle:
Principle #23Feedback

3Duration of action of moving object

If a capacitor with larger capacitance is used to extend current pulse duration, then the switching time is sufficient, but the space and cost increase

Engineering Contradiction:
Improvecurrent pulse durationVSAvoidcapacitor size
Core Design Contradiction:
Duration of action of moving objectVSVolume of moving object

Solution Approach 1:

The voltage regulator provides continuous voltage maintenance throughout the switching operation, ensuring that the current pulse through the relay coil maintains sufficient duration and magnitude. By continuously regulating the voltage rather than relying on a large capacitor to store energy for the entire duration, the system achieves adequate pulse duration with a smaller capacitor.

Inventive Principle:
Principle #20Continuity of useful action

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 solution allows for the use of a smaller capacitor while extending the duration of the current surge, preventing damage to the relay coil and reducing the need for high supply voltages, thus improving reliability and cost-effectiveness.

Implementation Method 1

a capacitor (2) connected in series with the relay coil (1)

Methodology Applied
Scientific EffectCapacitance: Capacitance

Implementation Method 2

at least one voltage regulator (100, 200) is provided which regulates the voltage applied to the relay coil (1) in such a way that it does not exceed a predetermined voltage

Methodology Applied
Scientific EffectVoltage regulation:

Implementation Method 3

the series circuit is connected to a supply voltage via a first semiconductor switch (5) to switch on the bistable relay and is short-circuited via a second semiconductor switch (7) to switch off the relay

Methodology Applied
Scientific EffectSemiconductor switching:

Data Source

PatentEP2891168B1Circuit arrangement for actuating a bistable relay
Publication Date: 2019.07.31 SMA SOLAR TECH AG
  • EP2891168B1 patent drawingFigure 1
  • EP2891168B1 patent drawingFigure 2
  • EP2891168B1 patent drawingFigure 3

AI summary

The invention relates to a circuit arrangement for actuating a bistable relay. A relay coil (1, 1a, 1b) of the bistable relay is arranged in a series circuit with a capacitor (2). The series circuit is connected to a supply voltage (V+) via a first semiconductor switch (5) in order to switch on the bistable relay, and the series circuit is short-circuited by means of a second semiconductor switch (7) in order to switch off the bistable relay. The circuit arrangement is characterized in that at least one voltage regulator (100, 200) is provided which regulates the voltage applied to the relay coil (1, 1a, 1b) of the bistable relay such that the voltage does not exceed a specified voltage.