Power Converter Duty Cycle Control for Line Regulation
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Solution Overview
Problem
Existing power converters face challenges in achieving high efficiency and high power density while maintaining good Line Regulation and Load Regulation, as fixed duty cycles result in poor output voltage stability with varying input voltages, and adjusting duty cycles over wide ranges complicates circuit design.
Innovation Solution
A power converter that adjusts its duty cycle within a narrow range based on input and output voltage sense signals, using a PWM controller and reference voltage module to maintain output voltage stability, with optional isolated signal transfer between primary and secondary sides.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the duty cycle of the switching circuit is adjusted within a wide range to maintain fixed output voltages, then good Line Regulation and Load Regulation are achieved, but the circuit design becomes complicated and efficiency decreases
Solution Approach 1:
The patent changes the control parameter from wide-range duty cycle adjustment to narrow-range duty cycle adjustment combined with output voltage feedback. The PWM controller adjusts the duty cycle within a limited range (e.g., 20%-80%) based on feedback from the output voltage, rather than requiring wide-range adjustment to compensate for all input voltage variations. This reduces circuit complexity while maintaining good line and load regulation.
2Reliability
If the duty cycle of the switching circuit is adjusted within a wide range to maintain fixed output voltages, then good Line Regulation and Load Regulation are achieved, but the efficiency and power density decrease
Solution Approach 1:
The patent optimizes the duty cycle operating range to improve efficiency. By limiting the duty cycle adjustment to a narrow range (e.g., 20%-80%) and using output voltage feedback to maintain stability, the system avoids extreme duty cycle values that reduce efficiency. This approach maintains good regulation while improving overall conversion efficiency and power density.
3Device complexity
If a fixed duty cycle is used for the switching circuit, then the circuit design is simple and power density is high, but the output voltage changes with input voltage resulting in poor Line Regulation
Solution Approach 1:
The patent introduces output voltage feedback to the PWM controller. The controller monitors the output voltage and adjusts the duty cycle within a narrow range to maintain stable output voltage despite input voltage variations. This feedback mechanism provides good line regulation while keeping the circuit design simple and power density high, avoiding the need for complex wide-range duty cycle adjustment circuits.
4Device complexity
If a fixed duty cycle is used for the switching circuit, then the circuit design is simple, but the output voltage stability deteriorates with varying input voltages
Solution Approach 1:
The patent implements output voltage feedback to the PWM controller, which continuously monitors output voltage stability and makes real-time adjustments to the duty cycle within a narrow range. This feedback control maintains stable output voltage despite input voltage variations, while keeping the circuit design simple and avoiding complex wide-range adjustment mechanisms.
Data Source
AI summary
A power converter includes a switching circuit, a power conversion circuit that receives an input voltage via the switching circuit and converts the input voltage into an output voltage, an input voltage sense circuit that detects the input voltage and generates an input voltage sense signal, and a PWM controller that adjusts a duty cycle of the switching circuit based at least in part on the input voltage sense signal. The power converter also includes an output sense circuit that detects the output voltage and generates an output voltage sense signal, wherein the PWM controller adjusts the duty cycle of the switching circuit based at least in part on the input voltage sense signal and the output voltage sense signal.