Power Converter Bandwidth Control via Error Amplifier Gain Adjustment
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Solution Overview
Problem
Conventional power converters have a fixed bandwidth, which leads to poor load transient performance when the switching frequency increases, resulting in a significant drop in output voltage due to the inability to adjust bandwidth accordingly.
Innovation Solution
An automatic bandwidth control system that adjusts the internal information frequency and increases the transconductance gain of the error amplifier in response to changing switching frequencies, allowing the power converter to maintain optimal performance across varying frequencies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the switching frequency of the power converter is increased, then the power conversion speed and efficiency are improved, but the load transient performance deteriorates due to significant output voltage drop caused by fixed bandwidth limitation
Solution Approach 1:
The patent implements dynamic bandwidth adjustment by modifying the error amplifier's transconductance gain according to the switching frequency. The bandwidth of the error amplifier is made variable rather than fixed, allowing it to adapt to different switching frequencies. This dynamic adjustment ensures that the control loop maintains optimal performance across varying operating conditions, preventing output voltage drops during load transients even at higher switching frequencies.
Solution Approach 2:
The patent changes the transconductance gain parameter of the error amplifier as a function of switching frequency. By adjusting this key electrical parameter, the bandwidth of the control loop is modified to match the switching frequency characteristics. This parameter change approach allows the system to maintain stability and performance across different operating points without requiring a complete redesign of the control architecture.
2Reliability
If the bandwidth of the error amplifier is increased to improve load transient performance, then the output voltage stability is improved, but the circuit complexity increases due to additional control components
Solution Approach 1:
The patent makes the existing error amplifier multi-functional by enabling it to operate with variable bandwidth depending on the switching frequency. Rather than adding separate fixed-bandwidth amplifiers for different frequency ranges, the single error amplifier is designed to adapt its characteristics dynamically. This universal approach maintains output voltage stability across different operating conditions while avoiding the complexity of multiple dedicated circuits.
Solution Approach 2:
The patent implements a feedback mechanism where the switching frequency information is used to adjust the transconductance gain of the error amplifier. This feedback loop automatically modifies the amplifier's bandwidth in response to changing operating conditions, ensuring optimal performance without requiring manual intervention or complex external control systems. The feedback approach simplifies the overall control architecture while achieving the desired adaptability.
Data Source
AI summary
An automatic bandwidth control system for any switching frequency of a power converter is provided. A pulse generator outputs a preset clock signal according to a comparing signal. A control circuit controls a first switch and a second switch according to frequencies of the preset clock signal and an external clock signal. A first current mirror is connected to an input voltage source and a first terminal of the first switch. A second comparator compares an output voltage of a second reference voltage source with an output voltage of the first current mirror to output the comparing signal. A second current mirror is connected to the input voltage source, an error amplifier and a first terminal of the second switch. A transconductance gain of the error amplifier is controlled by a current of the second current mirror to adjust a bandwidth of the power converter.