Power Supply Control Device Pseudo Switch Voltage Current Detection
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Solution Overview
Problem
Existing switching power supplies face challenges in accurately detecting inductor current, particularly at high switching frequencies, which hinders effective output feedback control and limits operational duty range.
Innovation Solution
A power supply control device is developed with a logic circuit generating a pseudo switch voltage and a filter unit producing a current sense signal simulating inductor current, allowing for differential current sense signals to perform output feedback control, including a configuration with capacitors, resistors, and a comparator for accurate current detection and control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional current detection methods are used in switching power supplies, then the basic power conversion function is maintained, but the inductor current detection accuracy deteriorates at high switching frequencies, limiting output feedback control effectiveness
Solution Approach 1:
The patent creates a pseudo switch voltage that copies the waveform characteristics of the actual switch voltage without requiring direct physical measurement. This copied voltage signal is then processed through RC circuits to generate current sense signals that accurately represent inductor current behavior even at high switching frequencies, resolving the detection accuracy limitation
Solution Approach 2:
The patent introduces RC circuits as intermediary elements that transform the pseudo switch voltage into current sense signals. These intermediary circuits filter and shape the voltage signal to produce accurate current information without requiring direct high-frequency current measurement, enabling effective output feedback control at elevated switching frequencies
2Measurement precision
If direct inductor current detection is implemented, then accurate current information is obtained, but additional amplifiers and complex circuitry are required, increasing device complexity and noise susceptibility
Solution Approach 1:
Instead of directly measuring the difficult-to-access inductor current, the patent copies the easily-obtainable switch voltage waveform and processes it through passive RC circuits. This approach eliminates the need for additional amplifiers and complex active circuitry, reducing device complexity and noise susceptibility while maintaining detection accuracy
Solution Approach 2:
The patent replaces complex active electronic components (amplifiers, current sensors) with simpler passive RC circuitry to achieve current detection. This substitution of mechanical/electronic complexity with simpler electrical RC time-constant-based processing reduces overall device complexity while maintaining the required measurement precision
3Adaptability or versatility
If the duty range is extended for broader output feedback control, then versatility improves, but maintaining accurate current detection and control stability becomes more difficult
Solution Approach 1:
The patent implements dynamic RC time constant circuits that adaptively process the pseudo switch voltage across varying duty cycles. The RC circuits naturally adjust their response characteristics based on the input signal duration, maintaining accurate current sense signal generation and control stability throughout the extended duty range without requiring additional stabilization mechanisms
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
This solution enables accurate pseudo-detection of inductor current and broader duty range output feedback control, effectively coping with higher switching frequencies without the need for additional amplifiers, enhancing efficiency and reducing noise susceptibility.
Implementation Method 1
a filter unit that receives input of the pseudo switch voltage and the output voltage or a feedback voltage corresponding thereto and generates a current sense signal
Implementation Method 2
a first resistor connecting the application terminal of the pseudo switch voltage and the application terminal of the positive side current sense signal, and a second resistor connecting the application terminal of the output voltage and the application terminal of the negative side current sense signal
Data Source
AI summary
The power supply control device includes a logic circuit for generating a pseudo switch voltage simulating a behavior of a switch voltage generated in the switch output stage, a filter unit that receives input of the pseudo switch voltage and the output voltage or a feedback voltage corresponding to the output voltage and generates a current sense signal simulating a behavior of the inductor current, and a feedback control unit that performs output feedback control of the switch output stage by using the current sense signal.