Switching Mode Power Supply Feedback Without Opto-Couplers
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Solution Overview
Problem
The high cost and large size of opto-couplers and shunt regulators in switching mode power supplies (SMPS) hinder their integration and increase costs, making it difficult to achieve efficient regulation of output DC voltage.
Innovation Solution
A SMPS design that uses a switching transistor, a switching controller, and a feedback signal generator to accurately detect output DC voltage without opto-couplers or shunt regulators, employing a PWM controller with an inductor, capacitor, and diode to generate and control the output voltage, and a voltage distribution unit to set a sampling period and store voltage levels as feedback signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If opto-couplers and shunt regulators are used for feedback in SMPS, then voltage regulation is achieved, but device size and cost increase
Solution Approach 1:
The patent extracts and eliminates the opto-coupler and shunt regulator from the feedback circuit. Instead, it uses a simple voltage divider network with resistors to generate the feedback voltage, thereby removing the bulky and expensive components while maintaining voltage regulation functionality.
Solution Approach 2:
The patent creates a simplified version of the feedback mechanism by using a voltage divider to generate a scaled-down version of the output voltage. This copied feedback signal is sufficient for control purposes without requiring the complex opto-coupler isolation architecture.
2Reliability
If opto-couplers and shunt regulators are used for feedback in SMPS, then voltage regulation is achieved, but manufacturing cost increases
Solution Approach 1:
The patent replaces expensive, long-lived components (opto-couplers and shunt regulators) with inexpensive resistors that form a voltage divider network. These simple passive components are significantly cheaper and easier to manufacture, thereby reducing overall device cost while maintaining the voltage regulation function.
Solution Approach 2:
By removing the expensive opto-coupler and shunt regulator from the circuit, the patent eliminates the primary cost drivers. The remaining feedback circuit uses only low-cost resistors, making the overall device much more cost-effective to manufacture.
3Extent of automation
If opto-couplers and shunt regulators are used in SMPS, then feedback control is enabled, but integration difficulty increases
Solution Approach 1:
The patent merges the feedback voltage generation function directly into the output voltage circuit using a voltage divider network. This integration eliminates the need for separate opto-coupler modules and shunt regulators, allowing the feedback control to be implemented as a unified, easily integrable circuit block.
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 allows for accurate detection and regulation of output DC voltage, reducing the need for expensive components and enabling more integrated and cost-effective SMPS solutions.
Implementation Method 1
a transformer and has a switching transistor at a primary side of a transformer that receives a DC voltage
Implementation Method 2
a switching transistor that is coupled to a primary coil at a primary side of a transformer for converting an input DC voltage
Implementation Method 3
an output unit that includes an inductor with one end connected to a second stage of the switching transistor, a capacitor with one end connected to the other end of the inductor, and a diode with an anode connected to the other end of the capacitor
Implementation Method 4
a capacitor with one end connected to the other end of the inductor
Implementation Method 5
an inductor with one end connected to a second stage of the switching transistor
Data Source
AI summary
A switching mode power supply includes a switching transistor, coupled to a primary coil at a primary side of a transformer for converting an input DC voltage, supplying power to a secondary and a tertiary coil at a secondary side of the transformer according to an operation of the switching transistor; a switching controller receiving a feedback voltage corresponding to a first voltage generated in the secondary coil and receiving a detection signal corresponding to a current of the switching transistor to generate a switching control signal for controlling the turn on/off of the switching transistor; and a feedback signal generator receiving the first voltage and the switching control signal to set a sampling period, and storing the first voltage, sampled with a last pulse of the first pulse string within the sampling period as a feedback voltage. The output voltage is thereby accurately detected without opto-couplers or shunt regulators.