Power Converter Switching Controller Using Depletion-Mode Transistor

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Solution Overview

Problem

Power converter circuits experience inefficiencies due to clamping and switching losses, particularly in diode-rectification and transistor-based rectification, which affect the timing of switching and result in reduced operational efficiency.

Innovation Solution

A power converter system with a switching controller that generates PWM signals based on the comparison of a control voltage and a predetermined switching threshold voltage, using a depletion-mode control transistor device to initiate operational voltage during startup and provide control voltage during normal operation, enabling zero-volt switching (ZVS) to mitigate switching losses.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of energy

If conventional switching power converter circuits use comparators to sense voltage amplitude and activate transistors for current flow, then DC voltages can be produced, but clamping losses and switching losses occur due to diode-rectification and transistor rectification, reducing operational efficiency

Engineering Contradiction:

Improveswitching losses and clamping lossesVSAvoidoperational efficiency

Core Design Contradiction:

Loss of energyVSProductivity

Solution Approach 1:

The patent converts the harmful switching losses and clamping losses into beneficial effects by implementing zero-volt switching (ZVS) through a depletion-mode control transistor device. This device generates control voltages that ensure the power switch turns on when the switching node voltage is zero, thereby eliminating switching losses. The same mechanism also eliminates clamping losses by preventing the need for reverse recovery current in the body diode of the power switch.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

Solution Approach 2:

The patent introduces a depletion-mode control transistor device as an intermediary between the switching node and the power switch gate. This intermediary generates control voltages based on the switching node voltage, enabling precise control of the power switch timing to achieve zero-volt switching and eliminate both switching and clamping losses.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Ease of operation

If the timing of switching is not optimized, then the power converter can operate, but it subjects the power converter to clamping losses based on diode-rectification and switching losses based on rectification with transistors

Engineering Contradiction:

Improveswitching timing controlVSAvoidclamping losses and switching losses

Core Design Contradiction:

Ease of operationVSLoss of energy

Solution Approach 1:

The patent implements feedback by using the switching node voltage to control the gate voltage of the power switch through the depletion-mode control transistor device. When the switching node voltage reaches zero, the control transistor generates a control voltage that turns on the power switch, ensuring zero-volt switching and eliminating both clamping and switching losses.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The patent replaces conventional mechanical or electronic switching control mechanisms with a field-effect-based control system using a depletion-mode control transistor device. This substitution enables precise, lossless control of switching timing by utilizing the electric field effect to generate control voltages that achieve zero-volt switching.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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 significantly reduces switching and clamping losses, allowing the power converter to operate more efficiently by implementing ZVS, thereby enhancing the overall efficiency of the power conversion process.

Implementation Method 1

The power switch can be controlled in response to a PWM signal to provide a primary current through a primary winding of the transformer to induce a secondary current in a secondary winding of the transformer to generate an output voltage

Methodology Applied

Scientific EffectElectromagnetic induction: Electromagnetic Induction

Data Source

PatentUS10886846B2Power converter with switching control

Publication Date: 2021.01.05 TEXAS INSTRUMENTS INC

AI summary

A power converter circuit includes a power stage comprising a transformer and a power switch. The power switch can be controlled in response to a PWM signal to provide a primary current through a primary winding of the transformer to induce a secondary current in a secondary winding of the transformer to generate an output voltage. The power stage includes a switching node having a switching voltage between the power switch and the primary winding. A switching controller includes a control transistor device to initiate an operational voltage associated with the control transistor device during a startup mode of the power converter circuit and to provide a control voltage based on an amplitude of the switching voltage during a normal operating mode. The switching controller generates the PWM signal in response to comparing the control voltage and a predetermined switching threshold voltage.