Bidirectional Bipolar Switch Circuit for Low-Drop Daisy Chains

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Solution Overview

Problem

Existing bidirectional switches in daisy chain power control systems experience significant voltage drops and fail to provide adequate power supply to control devices without defining input and output, limiting their effectiveness.

Innovation Solution

A bidirectional bipolar transistor switch arrangement using two PNP transistors connected in anti-parallel with low drop voltage diodes and a resistor, allowing for low voltage drop and independent power supply to control devices, with a single control signal capable of driving the switch.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If existing bidirectional switch methods are used, then power control in daisy chain is achieved, but significant voltage drop occurs across the switching device

Engineering Contradiction:

Improvepower control capabilityVSAvoidvoltage drop

Core Design Contradiction:

Ease of operationVSLoss of energy

Solution Approach 1:

The bidirectional switch is segmented into two separate bipolar transistors (Q1, Q2) connected in anti-parallel, each handling one direction of current flow. This segmentation allows each transistor to be optimized for low voltage drop in its respective conduction direction, resolving the contradiction between achieving power control and minimizing voltage drop.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The invention changes the operational parameters by using bipolar transistors configured to operate in saturation mode during conduction, which minimizes the voltage drop across the switching device. The transistors are designed with specific base resistor values (R1, R2) that ensure optimal saturation current, thereby reducing voltage drop while maintaining effective power control.

Inventive Principle:

Principle #35Parameter changes

2Ease of operation

If existing bidirectional switch methods are used, then switching control is achieved, but power supply for control device is not provided

Engineering Contradiction:

Improveswitching control capabilityVSAvoidpower supply to control device

Core Design Contradiction:

Ease of operationVSUse of energy by moving object

Solution Approach 1:

The bidirectional switch circuit is designed to perform multiple functions: it provides switching control for power flow direction while simultaneously generating power supply for the control device through the resistor network (R1, R2) connected to the transistor bases. This multi-functionality resolves the contradiction by making the switch circuit self-sufficient.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The control device is powered by the same bidirectional switch circuit that it controls. The resistor network connected to the transistor bases draws current from the power line, providing the necessary power supply to the control device without requiring an external power source, thus achieving self-service.

Inventive Principle:

Principle #25Self-service

3Adaptability or versatility

If bidirectional switch is implemented without defining input and output, then flexibility in daisy chain is improved, but voltage drop and power supply issues worsen

Engineering Contradiction:

Improveflexibility in daisy chain configurationVSAvoidvoltage drop

Core Design Contradiction:

Adaptability or versatilityVSLoss of energy

Solution Approach 1:

The bidirectional switch uses asymmetric component configuration - two different bipolar transistors (Q1, Q2) with different base resistors (R1, R2) optimized for their respective conduction directions. This asymmetric design allows each transistor to be tailored for minimal voltage drop in its specific operating direction, maintaining flexibility while reducing overall voltage drop.

Inventive Principle:

Principle #4Asymmetry

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 achieves a very low voltage drop across the switching device while ensuring power supply to control devices, enabling efficient power control in daisy chain configurations without defining input and output, and allowing for seamless operation by using a single control signal.

Implementation Method 1

a first bipolar transistor and a second bipolar transistor connected in anti-parallel between a first terminal and a second terminal

Methodology Applied

Scientific EffectBipolar transistor operation:

Implementation Method 2

a first diode connected with anode to the first terminal, a second diode connected with anode to the second terminal, the first diode and the second diode being connected via respective cathodes to a supply terminal

Methodology Applied

Scientific EffectDiode rectification: Diode

Data Source

PatentUS11522538B2Bidirectional switch for power control in a daisy chain

Publication Date: 2022.12.06 SCHNEIDER ELECTRIC IND SAS

AI summary

A bidirectional bipolar transistor switch arrangement, including: a first bipolar transistor and a second bipolar transistor connected in anti-parallel between a first terminal and a second terminal, a resistor connected to the base of the first bipolar transistor and the second bipolar transistor and to a control terminal, a first diode connected with anode to the first terminal, and a second diode connected with anode to the second terminal, the first diode and the second diode being connected via respective cathodes to a supply terminal. The bidirectional bipolar transistor switch arrangement is able to control the power supply within a daisy chain with low drop voltage.