Biasing Circuit Emulates Resistive Load for Electronic Transformers
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Solution Overview
Problem
Existing switching-mode power supply (SMPS) devices are not optimized to emulate a resistive load, which is required for proper operation with electronic transformers, leading to inefficiencies and increased costs due to the need for dedicated circuits and double inductive components.
Innovation Solution
A biasing and driving circuit that generates a sinusoidal current signal, modulated inversely proportional to the input voltage, is introduced to emulate a resistive load by modulating the voltage drop on the sensing resistor, allowing the SMPS to operate effectively with any generic electronic transformer without additional dedicated components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If SMPS devices are used without optimization for resistive load emulation, then the device complexity is reduced, but the compatibility with electronic transformers deteriorates
Solution Approach 1:
The SMPS device uses its own internal feedback input terminal and sensing resistor to generate the biasing current signal, eliminating the need for external dedicated components. The feedback terminal and sensing resistor serve dual purposes: their original function plus generating the sinusoidal biasing current for resistive load emulation.
Solution Approach 2:
The feedback input terminal and sensing resistor are made multi-functional by using them to generate the biasing current signal in addition to their original feedback function. This allows a single circuit to serve multiple purposes: standard voltage regulation and resistive load emulation, improving compatibility without adding components.
2Adaptability or versatility
If dedicated circuits and double inductive components are added to optimize SMPS for resistive load emulation, then the compatibility with electronic transformers is improved, but the device complexity and production costs increase
Solution Approach 1:
The circuit uses existing internal components (feedback terminal, sensing resistor) to generate the biasing current, eliminating the need for external dedicated circuits and reducing production costs while achieving resistive load emulation.
Solution Approach 2:
Existing components are made multi-functional to perform both their original functions and generate the sinusoidal biasing current, avoiding the need for additional dedicated components and reducing manufacturing complexity and cost.
3Device complexity
If the biasing current signal is generated using existing feedback components, then the device complexity is reduced, but the measurement precision of the feedback signal may deteriorate
Solution Approach 1:
The biasing current signal is generated using the feedback components, and the system accepts that this may partially affect the feedback signal precision. The patent acknowledges this trade-off and proceeds with the simpler implementation, as the primary function of voltage regulation is maintained.
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
The proposed solution enhances the power factor and reduces production costs by enabling SMPS devices to operate with any electronic transformer, improving the compatibility and efficiency of the SMPS with electronic transformers that require a resistive load.
Implementation Method 1
a rectifier input stage (30), for example obtained by a diode bridge (31-34), configured to receive the input voltage VIN on its own input terminals (30a, 30b) and generate a rectified input voltage VIN_R on its own output terminals (30c, 30d)
Implementation Method 2
a capacitor (40), which has the function of providing a filter
Implementation Method 3
a transconductance operational amplifier (56, 58) having a first input terminal (56a, 58a) coupled to the second intermediate operating voltage VP2 and a second input terminal (56b, 58b) coupled to the rectified input voltage VIN_R
Implementation Method 4
configured to supply the sinusoidal current signal I1 on the feedback input terminal 1c of the SMPS device 5 to modulate a feedback voltage signal generated on the feedback input 1c
Implementation Method 5
the inverting input of an error amplifier internal to the SMPS device 5 (regulation terminal)
Data Source
AI summary
An electronic system includes a feedback voltage regulator circuit including input terminals receiving a rectified alternating input voltage signal and a feedback input terminal receiving a feedback voltage that is generated based on a load current through an electric load. A sensing element senses the load current through the electric load and generates sensed voltage based upon the sensed load current. A current transducer receives the sensed voltage and provides the feedback voltage based upon the sensed voltage. A current generator receives the alternating input voltage signal and provides a biasing current signal that is a function of the alternating input voltage signal to modulate the feedback voltage on the feedback input terminal based upon the alternating input voltage signal.