Non-Isolated Power Supply Feedback Scheme Using Diode Voltage Sensing

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Solution Overview

Problem

Conventional feedback schemes for non-isolated power supplies require expensive high voltage components and can only sense output voltage once per switching cycle, limiting their effectiveness, especially at high voltages and in discontinuous modes of operation.

Innovation Solution

A feedback scheme that processes the voltage across the diode instead of the output voltage, using a controller with an operational amplifier and feedback resistors to generate a control signal that maintains an average output voltage over multiple switching cycles, eliminating the need for high voltage components and enabling continuous sensing.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Temperature

If a high voltage diode or high voltage BJT is used to send output voltage information to the controller, then the power supply can operate at high voltages, but the cost increases and the sensing capability is limited to once per switching cycle

Engineering Contradiction:

Improvevoltage handling capabilityVSAvoidcost and sensing frequency

Core Design Contradiction:

TemperatureVSDevice complexity

Solution Approach 1:

The patent introduces an intermediary capacitor connected between the switching node and the inverting input of the operational amplifier. This capacitor mediates the voltage information transfer, allowing the controller to sense output voltage continuously through integration without requiring expensive high voltage diodes or BJTs. The intermediary capacitor enables the system to handle high voltages while maintaining continuous sensing capability.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent replaces the mechanical/electronic switching-based sensing approach (using high voltage diodes or BJTs that can only sense once per cycle) with an analog integration approach using an operational amplifier and capacitor. This substitution enables continuous sensing by continuously integrating the voltage difference, eliminating the discrete sampling limitation of the conventional approach.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Device complexity

If conventional feedback sensing is used, then the circuit structure is simple, but the sensing can only occur once per switching cycle which limits control accuracy

Engineering Contradiction:

Improvecircuit structureVSAvoidoutput voltage sensing accuracy

Core Design Contradiction:

Device complexityVSMeasurement precision

Solution Approach 1:

The patent implements continuous sensing by using an operational amplifier to continuously integrate the voltage difference between the switching node and output. Instead of discrete sampling once per switching cycle, the integration process continuously accumulates voltage information, providing ongoing feedback for precise control. This continuous action maintains circuit simplicity while dramatically improving measurement precision.

Inventive Principle:

Principle #20Continuity of useful action

3Temperature

If high voltage components are used for feedback, then the power supply can handle high voltages, but the recovery from standby mode is slower

Engineering Contradiction:

Improvevoltage handling capabilityVSAvoidrecovery time from standby mode

Core Design Contradiction:

TemperatureVSLoss of time

Solution Approach 1:

The capacitor connected to the inverting input of the operational amplifier serves as an intermediary that stores voltage information. During standby mode, this capacitor maintains the integrated voltage information, allowing the controller to quickly resume accurate sensing and control when the power supply transitions from standby to active mode, thereby reducing recovery time.

Inventive Principle:

Principle #24Intermediary (Mediator)

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 continuous sensing of the output voltage and eliminates the need for high voltage components, improving control accuracy and efficiency across various operating conditions, including high voltages and discontinuous modes.

Implementation Method 1

integrating a difference between a voltage value of the generated reference signal, and a voltage difference between voltage values of the switching node and the second output terminal

Methodology Applied

Scientific EffectIntegration:

Data Source

PatentUS10153695B2Feedback scheme for non-isolated power supply

Publication Date: 2018.12.11 DIALOG SEMICONDUCTOR INC

AI summary

Embodiments described herein describe a switching power converter that includes a switch, an inductor, a diode, and a controller that generates a control signal to turn on and turn off the switch. The controller generates the control signal by generating a reference signal, integrating a difference between a voltage value of the generated reference signal, and a voltage difference between voltage values of the switching node and the second output terminal, and generating the control signal by processing the integrated voltage difference.