Transformer Reflected Voltage Sampling Circuit for Soft Switching
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Solution Overview
Problem
Existing power converter technologies fail to accurately measure signals from transformers, leading to inaccurate regulation of output voltage and discharge time, which is essential for achieving soft switching and synchronizing with valley voltage without optical-couplers and secondary-side regulators.
Innovation Solution
A multi-sampling circuit is introduced that generates sampling signals to measure the reflected voltage signal from a transformer's winding, storing these signals in hold capacitors and generating a buffer signal to compare with a level-shift signal, enabling precise measurement of discharge time and output voltage regulation without optical-couplers or secondary-side regulators.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If existing measurement methods are used for transformer signals, then device complexity is reduced, but measurement precision deteriorates
Solution Approach 1:
The patent divides the measurement process into multiple discrete sampling stages, where multiple sampling circuits independently measure different segments of the reflected voltage signal waveform. Each sampling circuit captures a specific portion of the signal, and the results are combined to achieve complete and accurate measurement of the entire signal cycle.
Solution Approach 2:
The patent transitions from single-point time measurement to multi-dimensional measurement by introducing multiple sampling circuits that operate at different time points and phases. This dimensional expansion in the time domain allows comprehensive capture of the reflected voltage signal characteristics that cannot be obtained through single-point measurement.
2Measurement precision
If optical-couplers and secondary-side regulators are used for output regulation, then measurement precision is improved, but device complexity and cost increase
Solution Approach 1:
The patent extracts the measurement function from the traditional optical-coupler feedback system and implements it directly on the primary side through dedicated sampling circuits. By taking out the measurement capability from the secondary side and placing it on the primary side, the system eliminates the need for optical-couplers and secondary-side regulators while maintaining accurate output regulation.
Solution Approach 2:
The patent enables the primary-side controller to perform self-measurement of the reflected voltage signal using integrated sampling circuits. The system serves itself by directly measuring the transformer's reflected voltage without external optical coupling components, achieving both simplified device structure and accurate regulation.
3Productivity
If discharge time measurement is not implemented, then device complexity is reduced, but productivity and efficiency deteriorate
Solution Approach 1:
The patent implements preliminary measurement of the discharge time parameter through dedicated sampling circuits that capture the voltage signal at specific time points. By pre-measuring the discharge characteristics, the system can optimize switching timing and improve overall efficiency without adding complex real-time control circuits.
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 solution allows for precise regulation of output voltage and discharge time measurement, enabling soft switching and synchronization with valley voltage, thereby improving the accuracy and efficiency of power converter operations.
Implementation Method 1
A sample-hold circuit is coupled to receive the sampling signals for sampling the reflected voltage signal. The reflected voltage signal multi-sampled by the sampling signals is stored into hold capacitors respectively.
Data Source
AI summary
A method and apparatus of sampling reflected voltage signal of a transformer is proposed. Sampling signals are used for generating hold voltages by sequentially sampling the reflected voltage from the transformer. A buffer circuit generates a buffer signal from the higher voltage of hold voltages. A sampling switch periodically conducts the buffer signal to produce a feedback signal according to an output of the buffer circuit. The feedback signal is proportional to output voltage of the transformer. A threshold signal added by the reflected voltage signal produces a level-shift signal. A discharge-time signal is enabled once the switching signal is disabled. The discharge-time signal is disabled once the level-shift signal is lower than output of the buffer circuit. The pulse width of the discharge-time signal is correlated to the discharge time of the transformer. The sampling signals are enabled to generate hold voltages when discharge-time signal is enabled.