Primary Side Control Power Supply Controller for Voltage Jitter
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Solution Overview
Problem
Primary side control (PSC) switching-mode power supplies experience excessive output voltage jitter during light-heavy load switching, as they take time to adjust energy output after load changes, often resulting in output voltage exceeding required specifications.
Innovation Solution
A power supply controller that uses a comparator to compare feedback voltage with an over-shot reference voltage, adjusting the switching frequency of a power switch to either 60 KHz or 25 KHz based on the comparison, allowing immediate reduction in electrical power output when the feedback voltage exceeds the reference, thereby preventing output voltage from rising further.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If primary side control (PSC) is used to reduce cost and improve efficiency, then photo coupler and secondary-side detection circuit are eliminated, but output voltage jitter increases during light-heavy load switching
Solution Approach 1:
The patent applies preliminary action by detecting the auxiliary winding voltage before the output voltage can rise excessively during light-heavy load transitions. The controller monitors the auxiliary winding voltage in real-time and takes preemptive control actions (adjusting duty cycle or switching frequency) before the output voltage deviates beyond specifications, thus preventing voltage jitter before it occurs.
Solution Approach 2:
The patent implements feedback control by continuously monitoring the auxiliary winding voltage, which reflects the output voltage status, and using this information to dynamically adjust the power switch control parameters. This closed-loop feedback mechanism enables the controller to compensate for load changes and maintain stable output voltage without requiring secondary-side detection circuits or photo couplers.
2Device complexity
If conventional PSC control is used, then device complexity is reduced, but response time to load changes increases causing voltage excursions
Solution Approach 1:
The patent uses feedback control by continuously monitoring the auxiliary winding voltage and dynamically adjusting power switch parameters based on detected load changes. This enables rapid response to load transitions while maintaining simple PSC architecture without secondary-side detection circuits.
Solution Approach 2:
The patent applies dynamics by making the control parameters (duty cycle or switching frequency) variable rather than fixed. The controller dynamically adjusts these parameters in real-time based on the monitored auxiliary winding voltage, enabling fast response to load changes while maintaining device simplicity.
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 solution effectively suppresses output voltage jitter by rapidly adjusting the switching frequency in response to load changes, ensuring the output voltage converges to the target value more quickly and within specifications.
Implementation Method 1
PSC indirectly detects voltage outputted by the secondary winding through directly detecting reflected voltage on an auxiliary winding
Data Source
AI summary
Power controllers and related primary-side control methods are disclosed. A disclosed power controller has a comparator and an ON-triggering controller. The comparator compares a feedback voltage with an over-shot reference voltage. Based on an inductance-coupling effect, the feedback voltage represents a secondary-side voltage of a secondary winding. Coupled to the comparator, the ON-triggering controller operates a power switch at about a first switching frequency when the feedback voltage is lower than the over-shot reference voltage. The ON-triggering controller operates the power switch at about a second switching frequency when the feedback voltage exceeds the over-shot reference voltage. The second switching frequency is less than the first switching frequency.