Voltage Converter Current Estimation in Diode Emulation Mode
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Solution Overview
Problem
Conventional power supply monitoring and control techniques face challenges in accurately determining the average output current during discontinuous conduction mode, as existing methods are either complex or inefficient, particularly in diode emulation mode, where the current is influenced by both peak and valley values and total switching period.
Innovation Solution
A current emulator and controller system that iteratively adjusts and refines an estimated average output current value over multiple power delivery cycles using a trial-and-error approach, incrementing and decrementing a count value based on switch activation and deactivation times, allowing for accurate current estimation without the need for complex divider circuits or large RC filters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a low pass filter is used to extract DC value from sampled current signal, then current measurement accuracy is improved, but response speed deteriorates due to very low bandwidth requirement
Solution Approach 1:
The patent extracts only the essential information needed for current measurement by sampling the current signal at specific moments (peak and valley points) rather than continuously sampling and filtering. This extraction approach achieves accurate current measurement without requiring a low pass filter, thereby maintaining fast response speed while improving measurement precision.
2Measurement precision
If a complex divider circuit is used to scale ADC output by (active time/total time), then current measurement accuracy is improved, but device complexity increases
Solution Approach 1:
The patent uses a simplified computational model that copies the essential relationship between active time, total time, and current measurement. Instead of implementing a complex hardware divider circuit, the solution uses software-based calculation that replicates the scaling function, achieving the same measurement accuracy with significantly reduced hardware complexity.
Solution Approach 2:
The patent replaces the mechanical/hardware divider circuit with a software-based computational approach. The current measurement is calculated using simple arithmetic operations (multiplication and addition) in the digital domain, substituting the need for complex analog divider circuitry while maintaining measurement precision.
3Measurement precision
If high-frequency clock signal routing is implemented for accurate current estimation, then measurement precision is improved, but power consumption increases
Solution Approach 1:
The patent implements periodic sampling of the current signal at specific phases of the switching cycle (peak and valley points) rather than continuous high-frequency sampling. This periodic action achieves accurate current estimation by capturing the essential waveform characteristics while significantly reducing the power consumption associated with high-frequency clock signal generation and processing.
Data Source
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AI summary
An apparatus includes a current emulator and a controller. The emulator receives a reference output current value representing a measured average amount of output current delivered by the voltage converter to the load for a first portion of a power delivery cycle during which high side switch circuitry and low side switch circuitry in the voltage converter are activated at different times to produce the output current. The power delivery cycle includes a second portion during which the high side switch circuitry and the low side switch circuitry of the voltage converter are deactivated. Via trial and error, the emulator derives an average output current value delivered to the load for the power delivery cycle based on the reference output current value and repeated adjustments to the estimation of the average output current. The controller controls operation of the voltage converter based on the derived average output current value.