Primary-Side Regulation Power Converter Sampling Circuit
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Solution Overview
Problem
Conventional primary-side-regulation power converters face challenges in achieving precise regulation of output current due to inherent operational errors in independent sampling circuitries, leading to reduced precision and increased manufacturing costs when operating in both continuous and discontinuous current modes.
Innovation Solution
The solution involves a controller apparatus comprising a switching circuit, signal generator, correlation circuit, and feedback modulator that generates a half signal and sampling pulses to sample the switching-current signal at its falling edge, allowing for the generation of a modulating current and adjustment of the switching signal's pulse width for precise regulation, thereby eliminating the need for two independent sampling circuitries.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If two independent sampling circuitries are utilized to sample switching-current signal magnitudes, then the continuous current can be calculated for regulation, but the manufacturing cost increases and layout space doubles
Solution Approach 1:
The patent extracts only the necessary sampling moment from the switching cycle by using a half-frequency clock signal. Instead of continuously sampling or using multiple independent sampling circuits, the invention samples the switching current at one specific moment (when the half-frequency clock transitions) which is sufficient to determine the continuous current component for regulation purposes.
Solution Approach 2:
The single sampling circuit performs multiple functions: it samples the switching current, determines both continuous and discontinuous current modes, and provides regulation information. This universal sampling approach eliminates the need for separate sampling circuitries for different current modes, reducing overall device complexity while maintaining measurement precision.
2Adaptability or versatility
If two independent sampling circuitries are used to sample switching-current signal, then regulation can be achieved in both continuous and discontinuous modes, but the manufacturing cost increases
Solution Approach 1:
The patent implements dynamic adaptation to different operating modes (continuous and discontinuous current modes) through a single sampling circuit that responds to the state of the switching current at the sampling moment. The controller dynamically determines the current mode based on the sampled value and adjusts regulation accordingly, eliminating the need for separate hardware for different modes and reducing manufacturing cost.
Solution Approach 2:
The invention changes the sampling parameter (sampling moment) based on the operating mode rather than using different hardware circuits. By sampling at the appropriate moment in the switching cycle and interpreting the sampled value in context of the expected current waveform, the system adapts to both continuous and discontinuous modes using the same physical circuitry, thereby reducing manufacturing cost.
3Measurement precision
If switching-current signal is sampled at the rising edge of driving signal, then a voltage spike appears making true continuous current value difficult to obtain, but sampling at other times requires complex circuitry
Solution Approach 1:
The patent applies preliminary action by using a half-frequency clock signal that is synchronized with and leads the switching signal. This pre-synchronized clock signal determines the exact sampling moment before the switching transient occurs, allowing the sampling circuit to capture the continuous current component without being affected by the voltage spike at the rising edge of the driving signal.
Solution Approach 2:
The half-frequency clock signal serves as an intermediary that mediates between the switching signal and the sampling circuit. This intermediary signal provides a clean, spike-free timing reference for sampling the switching current, eliminating the direct coupling between the switching transient and the sampling moment that would otherwise make accurate measurement difficult.
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 approach enhances the precision and reduces the manufacturing cost of regulating output current in primary-side-regulation power converters, enabling operation in both continuous and discontinuous current modes by sampling only one magnitude of the switching-current signal, thus improving regulatory accuracy and cost-effectiveness.
Implementation Method 1
A transformer 10 comprises a primary winding NP, a secondary winding NS and an auxiliary winding NA... The transformer 10 transfers the energy of an input voltage VIN to generate the output voltage VO
Implementation Method 2
Since the auxiliary winding NA and the secondary winding NS are magnetically coupled, the detection signal VDET obtained from the auxiliary winding NA will be correlated to an output voltage VO generated by the secondary winding NS
Data Source
AI summary
A method and an apparatus of operating a primary-side-regulation power converter at both continuous current mode and discontinuous current mode are provided. The apparatus includes a switching circuit, a signal generator, a correlation circuit, and a feedback modulator. The signal generator generates a half signal and a second sampling pulse in response to a switching signal. The correlation circuit receives the half signal, the second sampling pulse and a switching-current signal for generating a modulating current. The feedback modulator modulates a feedback signal in response to the modulating current, a detection signal and the switching signal. The detection signal obtained from a transformer is correlated to an output voltage of the primary-side-regulation power converter. An on-period of the half signal is half of an on-period of the switching signal. The switching-current signal is sampled at a falling-edge of the half signal.