Switching Converter Inductor Current Emulation for Short PWM Phases
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing power supply circuits face challenges in accurately emulating the current flowing through an inductor driven by a combination of high-side and low-side switches in switching converters, particularly due to the difficulty in measuring current during short phases.
Innovation Solution
A current emulator block measures and estimates the inductor current during longer phases and generates a replica of the current during shorter phases, using a combination of amplifiers, switches, and capacitors to provide an accurate representation of the inductor current.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If current measurement is performed during short phases in switching converters, then current emulation accuracy is improved, but measurement reliability deteriorates due to insufficient measurement time
Solution Approach 1:
The patent performs current measurement during the longer phase (when the high-side switch is ON) before the short phase occurs. By measuring the inductor current during the longer phase and using this measurement to represent the current during the short phase, the system obtains sufficient measurement time while still achieving accurate current emulation for control purposes.
Solution Approach 2:
The patent creates a copy of the inductor current measurement taken during the longer phase and uses this copied current value to represent the inductor current during the short phase. This copying approach allows the control system to have current information for the short phase without actually measuring during that brief period, thus resolving the contradiction between measurement accuracy and reliability.
2Reliability
If current measurement is performed during longer phases only, then measurement reliability is improved, but current emulation accuracy during short phases deteriorates
Solution Approach 1:
The patent measures the inductor current during the longer phase and creates a copy of this measurement that is used to represent the current during the short phase. This copying mechanism ensures that reliable measurements taken during the longer phase are effectively utilized to provide accurate current information for the short phase, maintaining both reliability and accuracy.
Solution Approach 2:
The patent makes the current measurement taken during the longer phase serve multiple functions: it represents the inductor current for both the longer phase and the short phase. This multi-functional use of a single measurement eliminates the need for separate measurements during each phase, improving reliability while maintaining sufficient accuracy for control purposes.
3Measurement precision
If separate current measurements are performed for high-side and low-side phases, then current emulation accuracy is improved, but device complexity increases
Solution Approach 1:
The patent uses a single current measurement taken during the high-side phase to represent the inductor current for both the high-side and low-side phases. This universal measurement approach eliminates the need for separate measurement circuits for each phase, reducing device complexity while still providing accurate current information for both phases through the use of the same measurement data.
Data Source
AI summary
A high-side switch and a low-side switch respectively drive the inductor in a first phase and a second phase periodically. The inductor current during a longer phase of the first phase and the second phase is measured as a first portion. Peak of the inductor current at a transition from the shorter phase to the longer phase is estimated. The estimating includes comparing an estimated magnitude with a first magnitude of the inductor current at the transition in a first period, and changing the estimated magnitude. The comparing and changing are repeated until the estimated magnitude equals the first magnitude to identify the peak. A second portion of the inductor current during the shorter phase is generated based on the estimated magnitude. The first and second portions are provided as an emulated current of the inductor current.