Artificial Ripple Modulator Control Circuitry for DC/DC Converters
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Solution Overview
Problem
Conventional peak current mode control methods for DC/DC converters are prone to noise interference due to reliance on output stage signals, affecting the accuracy of power switch control in power supply systems.
Innovation Solution
The implementation of artificial ripple modulator control circuitry that uses voltage proportional to input and output voltages, along with an error amplifier compensator output and clock signal, to control the ON and OFF timing of PWM signals, eliminating the need for complex additional circuitry and reducing noise influence.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional peak current mode control uses power switch or output inductor current feedback, then control of power switch can be achieved, but noise interference significantly impacts control accuracy
Solution Approach 1:
The patent extracts the control function from the noisy output stage signals and relocates it to the input stage by using input voltage sensing and artificial ripple generation. The control decision is made based on comparing the artificial ripple signal with a reference voltage, completely eliminating dependence on noisy inductor current or output voltage feedback signals.
Solution Approach 2:
The patent introduces an artificial ripple signal as an intermediary that mimics the behavior of inductor current without actually sensing it. This intermediary signal, generated through RC circuitry from the input voltage, serves as a noise-free proxy for current information, allowing control without direct current sensing.
2Reliability
If slope compensation circuitry is added to improve control stability, then power switch control can be maintained, but circuit complexity increases
Solution Approach 1:
The patent merges the functions of current sensing, slope compensation, and PWM generation into a single integrated circuit block. The RC circuitry simultaneously generates the artificial ripple signal and provides the timing reference for PWM, eliminating the need for separate current sensing amplifiers, slope compensation circuits, and timing generators.
Solution Approach 2:
The artificial ripple signal serves multiple functions simultaneously: it represents inductor current information, provides slope compensation for stability, and acts as the timing reference for PWM generation. This multi-functional approach eliminates the need for dedicated circuits for each function, reducing overall complexity.
Data Source
AI summary
A power supply system has a power switch circuit that switches an input voltage to generate a switched input voltage, an output circuit that generates an output voltage from the switched input voltage, and a pulse width modulation (PWM) controller that generates a PWM signal to control the power switch circuit. The PWM controller turns OFF the PWM signal based on a ramp signal that emulates a current of an output inductor and a feedback signal that indicates an error between the output voltage and a reference voltage.