Power Converter Controller with Adjustable Jitter Amplitude
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Solution Overview
Problem
Existing power converters in consumer electronic devices suffer from significant electromagnetic interference due to fixed switching frequencies, which cannot be effectively mitigated by current quasi resonant pulse width modulation modes, especially under low voltage and heavy load conditions.
Innovation Solution
A controller for power converters with adjustable jitter amplitude, utilizing a logic circuit to jitter feedback voltages or currents, thereby dynamically adjusting the turning-on time of the power switch to reduce electromagnetic interference by dispersing power in the frequency domain.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a fixed switching frequency is used in the power converter, then the power converter can operate efficiently with stable performance, but electromagnetic interference with high peak power is generated
Solution Approach 1:
The patent applies dynamics by making the switching frequency variable rather than fixed. A frequency control unit generates a frequency control signal that dynamically adjusts the switching frequency of the power switch based on feedback voltage, causing the switching frequency to fluctuate within a range rather than remain constant. This dynamic adjustment disperses the electromagnetic interference energy across a broader frequency spectrum, reducing peak power while maintaining stable operation.
Solution Approach 2:
The patent changes the frequency parameter of the power converter from a fixed value to a variable range. The frequency control unit modifies the switching frequency parameter based on the feedback voltage from the secondary side, allowing the frequency to vary dynamically. This parameter change transforms the electromagnetic interference characteristics, spreading energy over a wider bandwidth and reducing peak interference power.
2Device complexity
If quasi resonant pulse width modulation mode is used to naturally jitter the frequency, then the circuit operation is simplified, but the electromagnetic interference is not significantly reduced and peak power remains very large under low voltage and heavy load conditions
Solution Approach 1:
The patent introduces a frequency control unit as an intermediary component between the feedback voltage and the power switch control. This intermediary unit generates a frequency control signal that actively regulates the switching frequency, providing an additional control layer that enhances the jitter effect beyond what quasi resonant modulation alone can achieve. This intermediary mechanism effectively reduces peak electromagnetic interference power without significantly increasing overall system complexity.
Data Source
AI summary
A controller of a power converter with adjustable jitter amplitude includes a feedback pin, a logic circuit, an auxiliary pin, and a current sensing pin. The feedback pin is used for receiving a feedback voltage from a secondary side of the power converter. The feedback voltage corresponds to an output voltage of the secondary side of the power converter. The logic circuit is used for generating a jitter signal according to a clock, the feedback voltage, and a first resistor. The auxiliary pin is used for receiving a voltage corresponding to an auxiliary winding of the power converter. The current sensing pin is used for generating a detection voltage according to a current flowing through a primary side of the power converter. The voltage, the jitter signal, and the detection voltage determine turning-on time of the primary side of the power converter.