Current Resonant Power Supply Burst Control at Light Load

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Solution Overview

Problem

Current resonant power supply devices face challenges in maintaining efficiency at light loads, leading to increased losses and output overshoot due to frequent switching and unutilized reactive power.

Innovation Solution

A semiconductor device is introduced that includes a load detection circuit, a frequency setting signal generation circuit, a burst oscillation circuit, and a switch control circuit. This device detects light load states and generates frequency setting signals by combining feedback signals with adjustable multipliers and threshold-based signals, controlling the burst oscillation mode to reduce reactive power and losses.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If the frequency of burst oscillation mode is set according to the voltage of a specific end (e.g., VSB or VFB), then the switching element can be controlled to operate in burst oscillation mode at light load, but the switching times become more frequent, reactive power is not sent to the secondary side, losses increase, and output overshoot becomes large

Engineering Contradiction:

Improvepower consumption at light loadVSAvoidreactive power loss

Core Design Contradiction:

Use of energy by moving objectVSLoss of energy

Solution Approach 1:

The patent applies dynamics by making the frequency setting signal adjustable and adaptable to different operating conditions. The frequency setting signal generation circuit dynamically adjusts the burst oscillation frequency based on the output signal of the current resonant power supply, allowing the system to optimize its operation between light load and stable operation states, thereby reducing reactive power loss while maintaining power consumption efficiency

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The patent changes the frequency parameter of the burst oscillation mode by generating a frequency setting signal that is adjusted according to the output signal. This parameter change allows the system to transition from fixed frequency operation to variable frequency operation, optimizing the balance between power consumption and reactive power loss reduction

Inventive Principle:

Principle #35Parameter changes

2Stability of the object's composition

If the frequency of burst oscillation mode is set according to feedback signal with external phase compensation constant, then stable operation can be optimized, but it is difficult to adjust burst operation without affecting stable operation (switching frequency, burst cycle, noise)

Engineering Contradiction:

Improvestable operationVSAvoidadjustability of burst operation

Core Design Contradiction:

Stability of the object's compositionVSAdaptability or versatility

Solution Approach 1:

The patent segments the frequency setting function into separate components: the frequency setting signal generation circuit generates a frequency setting signal based on the output signal, while the external phase compensation constant is used separately for stable operation optimization. This segmentation allows independent adjustment of burst operation parameters without affecting stable operation characteristics

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent introduces an intermediary frequency setting signal that mediates between the output signal and the burst oscillation control. This intermediary signal allows the system to adjust burst operation parameters (switching frequency, burst cycle) independently from the stable operation parameters, enabling versatile adjustment without compromising stability

Inventive Principle:

Principle #24Intermediary (Mediator)

3Use of energy by moving object

If the switching element operates with frequent switching times in burst oscillation mode, then power consumption can be reduced at light load, but output overshoot becomes large

Engineering Contradiction:

Improvepower consumption at light loadVSAvoidoutput overshoot

Core Design Contradiction:

Use of energy by moving objectVSManufacturing precision

Solution Approach 1:

The patent applies feedback by generating the frequency setting signal based on the output signal of the current resonant power supply. This feedback mechanism allows the system to monitor the output and adjust the burst oscillation frequency accordingly, reducing output overshoot while maintaining efficient power consumption at light load

Inventive Principle:

Principle #23Feedback

Data Source

PatentUS20250125731A1Semiconductor device, current resonant power supply and control method thereof

Publication Date: 2025.04.17 SANKEN ELECTRIC CO LTD

AI summary

A semiconductor device used to control a current resonant power supply includes: a load detection circuit detecting a load state of the current resonant power supply; a frequency setting signal generation circuit generating first and second signals according to a feedback signal changing oppositely to an output signal of the current resonant power supply during a light load state and generating a frequency setting signal according to the first and second signals, and the first signal is a signal obtained by multiplying the feedback signal by a value N; a burst oscillation circuit generating a burst oscillation start signal according to the frequency setting signal; a switch control circuit generating a signal driving a first switching element and a second switching element connected in series with the current resonant power supply to turn on and off alternately according to the frequency setting signal and the burst oscillation start signal.