Selective Offset Control for Power Converter Dynamic Response

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Solution Overview

Problem

Power converters often experience overshoot and undershoot in their regulated output due to changes in load parameters, leading to potential shutdowns when these deviations exceed defined thresholds, as existing control circuits struggle to dynamically respond effectively.

Innovation Solution

A control circuit that generates a control signal for power switches based on an error signal, with the ability to selectively apply either a positive or negative offset signal to adjust the control signal in response to changes in output current, thereby enhancing the dynamic response and reducing overshoot and undershoot.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Speed

If conventional control circuits are used without selective offset signals, then the control circuit structure remains simple, but the dynamic response is slow and overshoot/undershoot occurs

Engineering Contradiction:

Improvedynamic response speedVSAvoidcontrol circuit complexity

Core Design Contradiction:

SpeedVSDevice complexity

Solution Approach 1:

The control circuit applies offset signals in advance to the control signal based on detected output current changes. When a load change is detected, the appropriate offset (positive or negative) is added to the PWM control signal before it reaches the power switch, proactively compensating for the expected voltage deviation and accelerating the dynamic response without waiting for the error amplifier to correct the deviation.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The control circuit dynamically selects and applies different offset signals based on the direction of output current change. The circuit includes detection logic that determines whether the load is increasing or decreasing and selectively applies positive or negative offsets accordingly, making the control system adaptive and dynamic rather than static.

Inventive Principle:

Principle #15Dynamics

2Reliability

If offset signals are applied to both increase and decrease error signals, then dynamic response improves, but incorrect offset application may worsen the error

Engineering Contradiction:

Improvecontrol accuracyVSAvoidovershoot and undershoot

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The control circuit employs asymmetric offset application where positive and negative offsets are not applied symmetrically to all error conditions. Instead, the circuit uses detection logic to determine the direction of load change and applies offsets asymmetrically - only applying the appropriate offset direction based on whether the load is increasing or decreasing, preventing incorrect offset application that would worsen the error.

Inventive Principle:

Principle #4Asymmetry

Solution Approach 2:

The control circuit uses feedback from the output current detection to control the selective application of offset signals. The detection circuit monitors output current changes and provides feedback to the control logic, which then determines whether to apply positive or negative offsets, ensuring that offsets are only applied when and where they will improve rather than worsen the regulation.

Inventive Principle:

Principle #23Feedback

3Loss of time

If the control circuit responds to load changes without offset signals, then the circuit operation remains stable, but the settling time is prolonged

Engineering Contradiction:

Improvesettling timeVSAvoidcontrol signal adjustment

Core Design Contradiction:

Loss of timeVSEase of operation

Solution Approach 1:

Inventive Principle:

Principle #10Preliminary action

Data Source

PatentUS10063140B2Control circuits for selectively applying error offsets to improve dynamic response in switching power converters

Publication Date: 2018.08.28 AES GLOBAL HLDG PTE LTD

AI summary

A control circuit for controlling a power circuit having a power switch includes a control loop configured to generate a control signal for the power switch of the power circuit based on an error signal determined by comparing a sensed parameter of the power circuit and a reference signal, and a positive offset signal and a negative offset signal each configured to adjust the control signal. The control circuit is configured to detect a change in an output current of the power circuit and selectively apply only one of the offset signals based on the change in the output current to adjust the control signal thereby enhancing a dynamic response to the change in the output current. Additional example control circuits, example power supplies and/or power converters including a control circuit for controlling a power switch, and example control methods are also disclosed.