Integrated Peak Voltage Detector for Fast Envelope Tracking
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Solution Overview
Problem
Existing power factor correction (PFC) systems face challenges in dynamically responding to fluctuations in mains voltage due to the quadratic relationship between gain and input voltage, leading to undershoots/overshoots and slow dynamical response, particularly when using external discrete components for RMS value detection.
Innovation Solution
A completely integrated peak detector architecture that isolates an integrated storage capacitance between peak events, using a controlled switch and rectifying circuit to maintain accurate peak value storage without external components, and includes a comparator to manage leakage and refresh the stored value, enabling fast detection of peak changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If external discrete components are used for RMS value detection, then the detection accuracy is improved, but the device complexity and integration level worsen
Solution Approach 1:
The patent merges the peak detection functionality with the existing integrated circuit by incorporating an integrated storage capacitance and controlled switch directly into the chip. This eliminates the need for external discrete components while maintaining accurate peak value storage and retrieval capabilities within the unified integrated circuit architecture.
2Measurement precision
If the storage capacitance is continuously connected to the oscillating voltage, then the peak value tracking is improved, but the leakage current increases causing drift
Solution Approach 1:
The patent implements periodic connection and disconnection of the storage capacitance to the oscillating voltage through a controlled switch. The capacitance is connected only during peak detection events and isolated between peaks, enabling periodic refreshing of the stored value while minimizing leakage current accumulation and drift during idle periods.
Solution Approach 2:
The controlled switch is activated in advance to connect the storage capacitance before a peak event occurs, allowing the capacitance to be properly charged to the peak value. After the peak is detected, the switch is opened to isolate the capacitance, preventing subsequent leakage from affecting the stored value until the next peak event.
3Measurement precision
If the error amplifier gain is increased to compensate for voltage fluctuations, then the regulation accuracy is improved, but the dynamical response worsens due to quadratic variation
Solution Approach 1:
The patent implements a feedback mechanism where the stored peak value (envelope voltage) is continuously compared with the instantaneous oscillating voltage by a comparator. This feedback loop enables the system to detect peak changes rapidly and trigger immediate corrective action, significantly improving the dynamical response to voltage fluctuations without requiring excessive amplifier gain.
Solution Approach 2:
The patent changes the operational parameter from continuous high-gain amplification to event-driven peak detection and comparison. By monitoring the difference between the stored envelope voltage and instantaneous voltage, the system achieves accurate regulation with faster response, as the comparator can quickly detect when peaks change rather than relying on slow amplifier response to continuous errors.
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 allows for rapid detection and adaptation to peak voltage changes, reducing leakage-induced drift and eliminating the need for external components, thereby improving the dynamical behavior and stability of PFC systems by maintaining accurate envelope voltage tracking between consecutive peaks.
Implementation Method 1
an integrated storage capacitance referred to a reference potential on which a voltage representing the value of the last detected peak is made available
Implementation Method 2
A rectifying circuit is input with the oscillating voltage and generates the rectified replica voltage on an output coupled to the tank capacitor
Data Source
AI summary
A peak detector circuit receives an oscillating power supply signal. A capacitor is selectably coupled to the signal and charged to a value corresponding to a peak value of the signal. A switch is then opened to isolate the capacitor. A comparator continually compares the signal with the value stored on the capacitor. When the signal rises to within a selected threshold, relative to the stored value, the comparator produces a command signal to close the switch, again coupling the capacitor to the signal. The peak detector can also include a tracking circuit that controls the capacitor to track the oscillating signal while the switch is closed, a timer circuit configured to close the switch and activate the tracking circuit if more than a selected time passes without production of a command signal, and a circuit configured to control the polarity of a leakage current of the capacitor.