Self-Oscillating Boost Converter with Varactor for Voltage Gain

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Solution Overview

Problem

Existing DC-DC boosting circuits face limitations in achieving greater-than-unity voltage gain while being compact and cost-effective, especially when dealing with unstable input sources, as they either require bulky digital controllers or are restricted to single-frequency operation.

Innovation Solution

The integration of a varactor device within the LC network of a self-oscillating boost converter, allowing for modulation of the self-resonant frequency and capacitance, enables greater-than-unity gain while maintaining compactness and adaptability to variable input sources, with the option of open-loop or closed-loop configurations for voltage regulation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Power

If a digital microcontroller is used to control the switching behavior of the transistor, then the voltage gain can be greater than unity, but the device size and cost increase significantly

Engineering Contradiction:
Improvevoltage gainVSAvoiddevice size
Core Design Contradiction:
PowerVSDevice complexity

Solution Approach 1:

The patent implements self-service by enabling the LC network to autonomously control the transistor switching behavior through self-oscillation at resonance. The circuit generates its own control signals without requiring an external digital microcontroller, thereby achieving voltage gain greater than unity while eliminating the bulky controller component. This is accomplished by configuring the LC network with specific component values that determine the oscillation frequency and duty cycle, allowing the circuit to regulate itself.

Inventive Principle:
Principle #25Self-service

2Device complexity

If a resonant converter is used to eliminate the need for an extrinsic source, then the device size is minimized, but the voltage gain is limited to at most unity

Engineering Contradiction:
Improvedevice sizeVSAvoidvoltage gain
Core Design Contradiction:
Device complexityVSPower

Solution Approach 1:

The patent applies parameter changes by carefully selecting and optimizing the values of LC network components (inductance L and capacitance C) to simultaneously achieve resonance operation and voltage gain greater than unity. By adjusting these parameters, the circuit operates at a specific resonant frequency where the impedance characteristics enable both self-oscillation and voltage amplification. This resolves the contradiction by showing that resonant operation does not inherently limit gain to unity when proper parameter selection is made.

Inventive Principle:
Principle #35Parameter changes

3Device complexity

If a single frequency and duty cycle are used in the self-oscillating network, then the circuit is simple, but it cannot adapt to variable input sources

Engineering Contradiction:
Improvecircuit simplicityVSAvoidadaptability to variable input
Core Design Contradiction:
Device complexityVSAdaptability or versatility

Solution Approach 1:

The patent implements dynamics by making the LC network parameters adjustable or variable rather than fixed. This allows the resonant frequency and duty cycle to adapt dynamically to changes in input voltage conditions. The circuit can switch between different operating modes or adjust component values to maintain optimal performance across varying input sources, thereby achieving both simplicity and adaptability.

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 efficient voltage stabilization and regulation across a range of input voltages, enhancing the voltage gain and frequency response of the converter, making it suitable for integrated and miniaturized applications.

Implementation Method 1

The integration of a varactor device within the LC network of a self-oscillating boost converter, allowing for modulation of the self-resonant frequency and capacitance

Methodology Applied
Scientific EffectVaractor effect: Capacitance

Implementation Method 2

The resonant converter is also operable at higher frequencies which allows for the miniaturization of component sizes

Methodology Applied
Scientific EffectResonance: Resonance

Implementation Method 3

an inductor, which helps the boosting of the input voltage

Methodology Applied
Scientific EffectElectromagnetic induction: Electromagnetic Induction

Data Source

PatentUS9397561B2Frequency dependent analog boost converter for low voltage applications
Publication Date: 2016.07.19 THE GOVERNORS OF THE UNIV OF ALBERTA
  • US9397561B2 patent drawing
  • US9397561B2 patent drawing
  • US9397561B2 patent drawing

AI summary

An analog open-loop self-oscillating boost converter is provided including: an output terminal for supplying an output voltage bus; an input terminal for receiving variable input power; a varactor positioned in series with the input terminal; and an oscillating network having an inductor, a resistor and a capacitor in a parallel orientation, the oscillating network connected to a semiconductor device and the varactor.