Phase-Shift PWM Control for Light-Load Power Converter Efficiency

Solution Overview

Problem

Conventional switching power converters face efficiency reduction and component wear due to increased switching losses and switching stresses at higher frequencies, and traditional phase shift full bridge converters struggle with poor efficiency under light load due to insufficient energy storage in the resonant inductor, necessitating increased inductance that raises volume and cost.

Innovation Solution

A novel control method for phase shift pulse width modulation that dynamically switches between hard and soft switching modes based on load conditions, using a digital signal processor to adjust duty cycles and generate appropriate modulation signals, without increasing resonant inductance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Volume of moving object

If the switching frequency is increased to reduce volume and weight, then the volume and weight of the switching power converter are reduced, but the switching losses increase and conversion efficiency decreases

Engineering Contradiction:

Improvevolume of switching power converterVSAvoidswitching losses

Core Design Contradiction:

Volume of moving objectVSLoss of energy

Solution Approach 1:

The patent applies dynamics by making the switching frequency variable rather than fixed. The controller dynamically adjusts the switching frequency based on load conditions: using higher frequencies for light loads and lower frequencies for heavy loads. This dynamic adaptation allows the system to maintain high conversion efficiency across different operating conditions while achieving reduced volume and weight through optimized frequency selection.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The patent changes the switching frequency parameter according to load conditions. By implementing variable frequency control where the switching frequency is adjusted based on the detected load state, the system optimizes the balance between volume reduction and efficiency maintenance. This parameter change strategy enables the converter to operate at optimal frequencies for different power levels.

Inventive Principle:

Principle #35Parameter changes

2Volume of moving object

If the switching frequency is increased, then the volume and weight are reduced, but the use life of switch components is shortened due to higher switching stresses

Engineering Contradiction:

Improvevolume of switching power converterVSAvoiduse life of switch components

Core Design Contradiction:

Volume of moving objectVSReliability

Solution Approach 1:

The patent implements dynamic switching frequency adjustment to reduce stress on switch components. By lowering the switching frequency under heavy load conditions, the system reduces the number of switching cycles and associated stresses on the power switches, thereby extending their operational life while maintaining compact size through optimized frequency selection.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The patent applies beforehand cushioning by proactively reducing switching frequency before excessive stress accumulates on the switch components. The controller monitors load conditions and preemptively adjusts the switching frequency to prevent overheating and fatigue damage, extending the reliability and使用寿命 of the power switch components.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

3Loss of energy

If the inductance of the resonant inductor is increased to improve light load efficiency, then the energy storage capability is improved, but the volume and cost of the circuit increase

Engineering Contradiction:

Improvelight load efficiencyVSAvoidvolume of circuit

Core Design Contradiction:

Loss of energyVSVolume of moving object

Solution Approach 1:

The patent applies dynamics by making the switching frequency variable rather than fixed. The controller dynamically adjusts the switching frequency based on load conditions: using higher frequencies for light loads and lower frequencies for heavy loads. This dynamic adaptation allows the system to maintain high conversion efficiency across different operating conditions while achieving reduced volume and weight through optimized frequency selection.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The patent changes the switching frequency parameter according to load conditions. By implementing variable frequency control where the switching frequency is adjusted based on the detected load state, the system optimizes the balance between volume reduction and efficiency maintenance. This parameter change strategy enables the converter to operate at optimal frequencies for different power levels.

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentUS12609603B2Method of controlling phase shift pulse width modulation of power converter

Publication Date: 2026.04.21 PHIHONG TECH CO LTD

AI summary

A method of controlling phase shift pulse width modulation of a power converter, the method includes a step of obtaining sampling signals of an output voltage and current of the power converter. Then, a digital signal processor is used to calculate an output power of the power converter. Next, a comparator is used to compare the output power of the power converter with a reference power. When the output power is less than the reference power, the modulation control of the switch of the power converter enters into hard-switching mode, and when the output power is greater than the reference power, the modulation control of the switch of the power converter enters into soft-switching mode.