Primary Side Regulator Eliminates Galvanic Isolation in SMPS
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Solution Overview
Problem
Conventional switched-mode power supplies with secondary side regulation face challenges such as high ripple in burst mode, increased standby power consumption, and the need for additional galvanic isolation, which increases costs and component tolerance errors, particularly in calibrating output voltage accuracy.
Innovation Solution
A switched-mode power supply design incorporating a primary side regulator and a tracking unit that adjusts a reference value based on feedback signals, eliminating the need for additional galvanic isolation and reducing component tolerance errors, while using a wake-up circuit to manage standby mode and load changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If secondary side regulation is used, then output voltage regulation accuracy is improved, but additional galvanic isolation components are required which increase costs and complexity
Solution Approach 1:
The patent extracts the regulation function from the secondary side and relocates it to the primary side. The controller on the primary side directly regulates the output voltage by controlling the switching element, eliminating the need for separate secondary side regulation components and additional galvanic isolation for feedback signals.
Solution Approach 2:
Instead of measuring output voltage on the secondary side and feeding back through galvanic isolation, the patent inverts the approach by measuring the primary side voltage and using it to indirectly control the output voltage. This reverses the traditional feedback path and eliminates the need for secondary side regulation hardware.
2Measurement precision
If secondary side regulator is used, then output voltage regulation is improved, but standby power consumption increases
Solution Approach 1:
The patent removes the secondary side regulator from the system and consolidates all regulation functions into the primary side controller. This eliminates the quiescent current consumption of secondary side regulation components during standby mode while maintaining output voltage regulation capability.
Solution Approach 2:
The patent merges the regulation function into the primary side controller, combining the switching control and voltage regulation into a single integrated system. This eliminates separate regulation components that would consume power during standby, reducing overall power consumption.
3Measurement precision
If conventional analog secondary side regulator is used, then regulation characteristic is improved, but component tolerance requirements increase costs
Solution Approach 1:
The patent replaces the analog secondary side regulator with a digital control system on the primary side. The controller uses digital processing to regulate output voltage, eliminating the need for precision analog components and their associated tight tolerance requirements, thereby reducing manufacturing costs.
Solution Approach 2:
The patent changes the regulation approach from analog to digital domain. By implementing regulation algorithms in the digital controller, the system achieves precise regulation characteristics without being constrained by analog component tolerances, allowing for more relaxed and cost-effective component selection.
4Ease of manufacture
If primary side regulation is used, then manufacturing costs are reduced, but output voltage measurement accuracy deteriorates
Solution Approach 1:
The patent implements a feedback mechanism where the controller on the primary side continuously monitors the output voltage (indirectly through primary side measurements) and adjusts the switching duty cycle accordingly. This closed-loop feedback ensures accurate output voltage regulation despite using primary side measurement, compensating for transformer ratio variations and component tolerances.
Solution Approach 2:
The patent changes the measurement parameter from direct secondary side voltage to primary side voltage that correlates with output voltage. By measuring the voltage across the primary winding and using the known transformer turns ratio (or through iterative calibration), the system achieves accurate output voltage control without direct secondary side measurement, reducing component tolerance requirements.
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 design reduces manufacturing costs, minimizes standby power consumption, and enhances output voltage regulation accuracy without the need for additional galvanic isolation, achieving ±5% accuracy without calibration.
Implementation Method 1
The switching converter has a transformer in order to provide galvanic isolation between a primary side and a secondary side of the switching converter
Data Source
AI summary
A switched-mode power supply includes: a switching converter converts an input voltage into an output voltage in accordance with a switching signal, wherein the switching converter includes a transformer providing galvanic isolation between a primary side and a secondary side of the switching converter; and a wake-up circuit connected to the secondary side of the switching converter, the wake-up circuit coupled to the secondary side of the switching converter and operable to generate a feedback signal that indicates whether the output voltage is greater than or equal to a threshold value. A primary side regulator generates a control signal depending on a reference value and a measured value (VAUX) representing the output voltage. Primary side logic generates the switching signal depending on the control signal. A tracking unit receives the feedback signal via a galvanically isolating component and adjusts the reference voltage based on the feedback signal.