Bidirectional B-TRAN Switching for Low On-State Voltage Drop

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Solution Overview

Problem

Conventional power-packet-switching power converters face inefficiencies due to the diode drop problem in IGBTs and the lack of conductivity modulation in FETs, leading to high switching losses and slow turn-off times, which are exacerbated by the need for bidirectional operation.

Innovation Solution

The development of fully-symmetric double-base bipolar junction transistors (B-TRANs) with a 'collectorless' structure, where emitter and base structures are formed on both surfaces of a semiconductor wafer, allowing for high non-equilibrium carrier concentration and low on-state voltage drop, achieved through heavy base current application and innovative base drive circuits.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of energy

If conventional IGBTs are used for bidirectional switching, then voltage blocking capability is achieved, but diode drop losses increase switching energy consumption

Engineering Contradiction:

Improveswitching lossesVSAvoidenergy consumption

Core Design Contradiction:

Loss of energyVSUse of energy by moving object

Solution Approach 1:

The patent changes the operating parameters of the bipolar transistor by applying heavy base current to drive the device into high non-equilibrium carrier concentration, transforming the on-state voltage drop from conventional diode-level losses to less than a diode drop, thereby reducing switching energy consumption

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent implements dynamic base drive circuits that actively control the base current to achieve rapid transitions between on and off states, enabling fast turn-off times and reducing the duration of high-loss states during switching operations

Inventive Principle:

Principle #15Dynamics

2Speed

If conventional FETs are used for switching, then switching speed is improved, but lack of conductivity modulation increases on-resistance

Engineering Contradiction:

Improveturn-off timeVSAvoidswitching losses

Core Design Contradiction:

SpeedVSLoss of energy

Solution Approach 1:

The patent changes the carrier concentration parameter in the base region through heavy base current injection, creating high non-equilibrium carrier concentration that provides conductivity modulation, thereby reducing on-resistance while maintaining fast switching capability

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent creates a composite effect by combining the fast switching characteristics of FETs with the conductivity modulation capability of bipolar transistors, achieving both fast turn-off times and low on-resistance through the double-base bipolar transistor structure

Inventive Principle:

Principle #40Composite materials

3Adaptability or versatility

If bidirectional operation is implemented in conventional devices, then versatility is improved, but device complexity increases

Engineering Contradiction:

Improvebidirectional operation capabilityVSAvoiddevice structure complexity

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent uses asymmetric base contact configuration where one base contact is heavily doped and the other is lightly doped, enabling bidirectional operation through asymmetric carrier injection and collection mechanisms, achieving versatility without requiring fully symmetric complex structures

Inventive Principle:

Principle #4Asymmetry

Solution Approach 2:

The double-base bipolar transistor structure serves multiple functions: it provides bidirectional switching, voltage blocking, conductivity modulation, and fast turn-off capability within a single device, reducing the need for additional components and simplifying the overall circuit complexity

Inventive Principle:

Principle #6Universality (Multi-functionality)

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

B-TRANs provide bidirectional switching with less than a diode drop, high voltage resistance, and low on-resistance, enabling efficient operation in power-packet-switching power converters with reduced switching losses and improved turn-off times.

Implementation Method 1

applying heavy base current to generate high non-equilibrium minority carrier concentration in the base region

Methodology Applied

Scientific EffectMinority carrier injection:

Implementation Method 2

high non-equilibrium minority carrier concentration in the base region, achieved through heavy base current application

Methodology Applied

Scientific EffectCarrier recombination:

Implementation Method 3

first and second first-conductivity-type emitter regions, and first and second second-conductivity-type base contact regions

Methodology Applied

Scientific EffectElectrical conduction: Conduction (electrical)

Data Source

PatentUS9900002B2Methods of operating a double-base-contact bidirectional bipolar junction transistor

Publication Date: 2018.02.20 IDEAL POWER INC

AI summary

Methods, systems, circuits, and devices for power-packet-switching power converters using bidirectional bipolar transistors (B-TRANs) for switching. Four-terminal three-layer B-TRANs provide substantially identical operation in either direction with forward voltages of less than a diode drop. B-TRANs are fully symmetric merged double-base bidirectional bipolar opposite-faced devices which operate under conditions of high non-equilibrium carrier concentration, and which can have surprising synergies when used as bidirectional switches for power-packet-switching power converters. B-TRANs are driven into a state of high carrier concentration, making the on-state voltage drop very low.