Power Supply Output Voltage Control for Software Current Limiting

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Solution Overview

Problem

Existing hardware-based solutions for overcurrent protection in power supply systems, such as vehicle-to-load (V2L) systems, face challenges with fixed component values, sensitivity to manufacturing tolerances, limited adaptability, forced cutoff of PWM output, and increased design complexity, leading to inconsistent performance and potential harmonic distortion.

Innovation Solution

Implementing a software-based control algorithm using a virtual resistance component to limit output current, which calculates a virtual resistance value when the current exceeds a predetermined limit, adjusting the PWM duty value to control output voltage and current, thereby enabling precise and adaptable current limiting without hardware changes.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If hardware-based overcurrent protection is implemented, then output current can be limited to prevent damage, but the system complexity increases and adaptability decreases

Engineering Contradiction:

Improveovercurrent protectionVSAvoidcircuit design complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent replaces hardware-based overcurrent protection circuits with a software-based control algorithm. The controller monitors output current and dynamically adjusts PWM duty cycle to limit current, eliminating the need for complex hardware protection circuits while maintaining reliable overcurrent protection.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent changes the approach from fixed hardware parameters to dynamically adjustable software parameters. The current limit value and PWM duty cycle are controlled through software, allowing flexible parameter adjustment without physical circuit modifications, thereby reducing device complexity while maintaining protection reliability.

Inventive Principle:

Principle #35Parameter changes

2Ease of manufacture

If hardware components with fixed values are used, then current limit can be set, but adaptability to change system requirements is limited

Engineering Contradiction:

Improvefixed component valuesVSAvoidsystem adaptability

Core Design Contradiction:

Ease of manufactureVSAdaptability or versatility

Solution Approach 1:

The patent implements dynamic current limiting through software control instead of fixed hardware components. The controller can adjust the current limit value and PWM duty cycle in real-time based on system requirements, enabling the system to adapt to changing conditions without physical component changes.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The software-based control algorithm serves multiple functions: it provides overcurrent protection, enables flexible parameter adjustment, and allows the system to adapt to different operating conditions. This universal software solution replaces multiple fixed-value hardware components with a single adaptable control system.

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Reliability

If PWM output is forcibly cut off for overcurrent protection, then system damage is prevented, but output voltage waveform distortion occurs

Engineering Contradiction:

Improvesystem protectionVSAvoidharmonic distortion

Core Design Contradiction:

ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The patent employs feedback control where the controller continuously monitors output current and adjusts PWM duty cycle accordingly. When overcurrent is detected, the controller gradually reduces PWM duty cycle to limit current, rather than forcibly cutting off the output. This feedback mechanism prevents system damage while maintaining waveform quality and minimizing harmonic distortion.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The controller performs periodic monitoring of output current and makes incremental adjustments to PWM duty cycle. This periodic control action allows smooth current limiting that prevents sudden waveform disruptions and reduces harmonic distortion while still providing effective overcurrent protection.

Inventive Principle:

Principle #19Periodic action

4Reliability

If hardware drive logic is added for overcurrent control, then current limiting capability is improved, but production cost and design time increase

Engineering Contradiction:

Improvecurrent limiting capabilityVSAvoidproduction cost

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The patent replaces hardware drive logic circuits with software-based control algorithms implemented in the controller. This substitution eliminates the need for additional protection circuits, reducing component count, simplifying manufacturing, and lowering production costs while maintaining current limiting capability.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent merges the overcurrent protection function with the existing controller and PWM control logic. Instead of adding separate hardware protection circuits, the protection functionality is integrated into the software control algorithm, reducing overall system complexity and production cost while maintaining current limiting capability.

Inventive Principle:

Principle #5Merging (Combining)

Data Source

PatentUS12542448B2Apparatus and method for limiting output current using output voltage control technique

Publication Date: 2026.02.03 HL MANDO CORP

AI summary

Provided is a method for controlling an output voltage in a power supply system, including calculating, by a virtual resistance calculator, a virtual resistance value when a value of a measured output current exceeds a predetermined current limit value; calculating a signal input to a controller based on the calculated virtual resistance value; and generating, by the controller, a signal for controlling an output voltage based on the signal input to the controller.