Switched Power Supply Delay Measurement Correction
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Solution Overview
Problem
Existing switched mode power supplies (SMPS) face inefficiencies due to errors in current measurement caused by delay offsets between digital PWM signals and actual switching operations, leading to incorrect calculation of average inductor current, which affects operation mode selection and overall efficiency.
Innovation Solution
A method that detects and corrects for delay offsets by calculating a corrected midpoint of the switching signal's half phase, generating a sampling pulse based on this correction, and sampling the current at the output node to accurately measure the average inductor current, thereby improving measurement accuracy and operational efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Extent of automation
If digital PWM signals are used for switch control, then switching operation is enabled, but delay offset between signal and actual switching causes measurement error
Solution Approach 1:
The patent applies preliminary action by detecting the delay offset between the PWM signal and actual switching operation in advance, then using this detected delay to correct the sampling timing. The system measures the delay during initialization or calibration and stores it for subsequent compensation, allowing the current sampling to occur at the correct midpoint despite the inherent signal-to-switching delay.
2Ease of operation
If current sampling is performed at fixed midpoint, then sampling is simple, but delay offset causes incorrect average current calculation
Solution Approach 1:
The patent implements feedback by using the detected delay offset to adjust and correct the sampling timing. The system continuously monitors the relationship between PWM signals and actual switching, detects the timing discrepancy, and feeds this information back to modify the sampling point calculation, ensuring that current sampling occurs at the accurate midpoint despite the delay.
3Device complexity
If delay offset is not corrected, then system operation is simple, but operation mode selection becomes incorrect
Solution Approach 1:
The patent applies preliminary action by detecting and storing the delay offset during system initialization or calibration before normal operation begins. This pre-detected delay value is then used to correct sampling timing throughout operation, enabling accurate operation mode selection without adding complexity to the ongoing switching and control processes.
Data Source
AI summary
According to an embodiment, a method of operating a switching power supply includes applying a periodic switching signal to a first switch that is coupled to an output node, detecting an offset delay between applying the periodic switching signal and a change in voltage of the output node, calculating a corrected midpoint of a half phase of the periodic switching signal based on the offset delay, generating a sampling pulse based on the corrected midpoint, and sampling a current at the output node according to the sampling pulse.