Switching Power Supply Resonance Current Control
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Solution Overview
Problem
Current switching power supply apparatuses face slow response times to load fluctuations due to large capacitance values in phase compensation capacitors, leading to inefficient burst and continuous operation transitions, and require external voltage division circuits that increase costs and accuracy requirements, especially at no-load conditions.
Innovation Solution
A method for controlling a switching power supply apparatus by detecting resonance current after-inversion time and calculating it based on feedback signals, allowing for precise timing of switching element turn-off, thereby improving responsiveness to load changes without the need for external voltage division circuits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a large capacitance value phase compensation capacitor is used in voltage mode control, then the output voltage is controlled to be constant, but the speed at which the switching power supply apparatus returns to continuous operation after a sudden increase in load is slow
Solution Approach 1:
The patent replaces the voltage mode control mechanism with a current mode control mechanism. Instead of using a large capacitance phase compensation capacitor to control output voltage, the invention uses current detection and comparison circuits that directly sense the resonance current and compare it with reference values to control switching timing. This substitution of control mechanism eliminates the need for large capacitance values while achieving both voltage stability and fast response.
Solution Approach 2:
The patent changes the control parameter from voltage feedback (with large capacitance) to current feedback (with fast response). By detecting the resonance current and using its instantaneous value for control decisions, the system achieves rapid response to load changes. The control parameter transition from integrated voltage signal to instantaneous current signal resolves the contradiction between stability and speed.
2Measurement precision
If external voltage division circuits are used to detect input voltage and resonance capacitor voltage, then voltage detection is achieved, but the costs increase and accuracy requirements become greater
Solution Approach 1:
The patent makes the resonance current detection circuit serve multiple functions. The same current detection circuit that controls switching timing also provides information for determining operating conditions (burst vs. continuous operation). This self-service approach eliminates the need for separate external voltage division circuits, reducing component count and cost while maintaining measurement accuracy through the inherent precision of the current sensing mechanism.
Solution Approach 2:
The patent creates a universal control circuit that performs multiple functions: it detects resonance current for switching control, determines load conditions, and manages both burst and continuous operation modes. This multi-functional circuit replaces what would otherwise require separate voltage division circuits and control logic, simplifying the overall device while maintaining or improving measurement accuracy.
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 enhances the responsiveness to sudden load changes, reduces component costs, and maintains accurate control across varying load conditions, including no-load scenarios, by eliminating the need for external voltage division circuits and improving the efficiency of burst and continuous operation transitions.
Implementation Method 1
The resonance circuit includes a resonance inductor, an excitation inductor of a transformer, and a resonance capacitor. The resonance circuit receives the rectangular voltage, performs a resonance operation, and outputs an alternating voltage to the secondary side of the transformer.
Data Source
AI summary
First, it is assumed that a low-side switching element is turned off. At this time a resonance current before-inversion time is counted. When a resonance current is inverted, a count value is held and the counting operation of a resonance current after-inversion time is begun. Next, a target value of the resonance current after-inversion time at which a high-side switching element is to be turned off is calculated based on a feedback signal and the counting operation of the resonance current after-inversion time is continued. When a count value reaches the target value, the counting operation of the resonance current after-inversion time is ended and the high-side switching element is turned off. After a high-side half cycle is controlled, a low-side half cycle is controlled in the same way. Responsiveness to a sudden change in load is improved by exercising control every half cycle.