Switching Power Converter Controller with Noise Rejection
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Solution Overview
Problem
Existing switching power converter control methods face challenges in achieving good stability and transient response, especially under high-voltage conditions, due to poor ground noise rejection and inaccurate inductor current sensing, which affects the ability to provide a regulated output voltage effectively.
Innovation Solution
A controller for switching power converters that incorporates a pulse width modulation comparator with a signal extractor and differential amplifier, filtering the output voltage to separate noise components and improve noise rejection, allowing for accurate control of power switches and enhanced transient response.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If inductor current is sensed from the inductor input node (SW node), then accurate inductor current information is obtained, but the cost and complexity increase for high-voltage converters
Solution Approach 1:
The patent introduces an intermediary sensing approach by sensing inductor current from the output node rather than directly from the high-voltage input node. This intermediary location provides a safer, lower-voltage access point for current sensing while still capturing accurate inductor current information through the relationship between input and output currents in the switching converter topology.
2Ease of manufacture
If inductor current is sensed from the inductor output node, then cost is reduced and transient response is improved, but accurate inductor current information cannot be obtained when different external components are used
Solution Approach 1:
The patent implements a feedback mechanism where the sensed output voltage is fed back through a feedback path that includes the inductor current sense signal. This feedback loop allows the controller to accurately determine inductor current information by combining the output voltage feedback with the current sensing signal, compensating for variations in external components and maintaining measurement accuracy across different operating conditions.
3Speed
If sensing is performed from both inductor input and output nodes, then transient response is improved, but the difficulty of sensing under high-voltage applications increases
Solution Approach 1:
The patent extracts the essential current sensing function from the high-voltage input node and relocates it to the lower-voltage output node. By taking out the current sensing operation from the hazardous high-voltage environment and performing it at the safer output node, the system achieves fast transient response without the complexity and safety issues associated with dual high-voltage sensing points.
4Ease of manufacture
If conventional sensing approaches are used, then implementation is simple, but ground noise rejection is poor
Solution Approach 1:
The patent uses the output voltage feedback as an intermediary signal that carries information about both the output voltage level and the inductor current effects. By processing this intermediary feedback signal through the feedback path, the system achieves good ground noise rejection because the feedback signal is referenced to the same ground as the control circuit, naturally rejecting common-mode ground noise while maintaining 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
The solution effectively rejects ground noise and provides improved transient response and stability, enabling precise control of the switching power converter even under high-voltage conditions, leading to better regulation of output voltage during load transients.
Implementation Method 1
The signal extractor is arranged to filter the output voltage to obtain a first voltage signal in a first frequency range and a second voltage signal in a second frequency range
Implementation Method 2
the signal extractor is arranged to filter the output voltage to obtain a first voltage signal in a first frequency range and a second voltage signal in a second frequency range being different from said first frequency range, said first and second voltage signals sharing a common noise component; and to present said first and second voltage signals as respective first and second inputs to the differential amplifier
Data Source
AI summary
A switching power converter with good stability and transient response is presented. There is provided a controller for a switching power converter of the type comprising one or more power switches. The controller contains a pulse width modulation comparator arranged to output a digital control signal to control the power switches of the switching power converter. A first input of the pulse width modulation comparator is derived from an output voltage of the switching power converter via a first feedback path. A second input of the pulse width modulation comparator is derived from the output voltage of the switching power converter via a second feedback path. One of the feedback paths has a signal extractor and a differential amplifier arranged to filter the output voltage and to provide good ground noise rejection.