Power Supply Apparatus Nonlinear Current Correction
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Solution Overview
Problem
Conventional current resonance power supply apparatuses face inefficiencies due to high power loss and increased size requirements, particularly in overcurrent detection, which are exacerbated by variations in input AC voltage and the need to prevent off-resonance phenomena, leading to increased costs and reduced size reduction in power supply devices.
Innovation Solution
A power supply apparatus with a transformer having a primary, secondary, and auxiliary winding, and a nonlinear correction unit that corrects current detection results based on input voltage, ensuring stable overcurrent protection and reducing the size of the transformer and current resonance capacitor by maintaining constant current through the load.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a current detection resistor is connected in series to the resonance circuit to detect overcurrent, then overcurrent detection is achieved, but power loss increases and efficiency decreases
Solution Approach 1:
The patent extracts the current detection function from the main power path by using a capacitor connected in parallel with the resonance capacitor. The detection capacitor is connected to the OCP terminal through a high-value resistor, allowing current detection without placing a resistive element in the series path of the resonance circuit, thereby eliminating the power loss associated with series detection resistors.
Solution Approach 2:
The patent introduces an intermediary detection capacitor and high-value resistor combination to measure the resonance current. The detection capacitor converts the series current into a parallel current that can be measured through the high-value resistor without significantly affecting the main power flow, thus detecting overcurrent conditions while maintaining high efficiency.
2Measurement precision
If multiple resistors are connected in parallel or series to configure a current detection resistor, then detection capability is improved, but device size and space requirements increase
Solution Approach 1:
The patent removes the need for multiple detection resistors by using a single detection capacitor in parallel with the resonance capacitor. This extraction of the detection function to a parallel configuration eliminates the need for multiple series or parallel resistors, significantly reducing the space required for current detection components.
3Adaptability or versatility
If the input AC voltage varies, then the power supply must handle voltage fluctuations, but current detection accuracy becomes inconstant leading to unreliable overcurrent protection
Solution Approach 1:
The patent implements feedback by connecting the detection capacitor through a high-value resistor to the OCP terminal of the control IC. This feedback mechanism continuously monitors the current through the resonance capacitor and provides real-time overcurrent protection signals to the control IC, which adjusts the switching duty cycle accordingly, maintaining reliable protection despite input voltage variations.
Solution Approach 2:
The patent changes the detection parameter from voltage-based detection (which is affected by input voltage variations) to current-based detection through the detection capacitor. By measuring the current through the resonance capacitor directly, the system achieves consistent detection accuracy regardless of input AC voltage fluctuations, as the capacitor current is determined by the resonance circuit characteristics rather than the input voltage level.
4Reliability
If the transformer and current resonance capacitor are increased in size to prevent off-resonance phenomena, then reliability is improved, but the overall apparatus size increases contradicting miniaturization goals
Solution Approach 1:
The patent applies dynamic control by using pulse-width modulation (PWM) to adjust the switching duty cycle of the MOSFETs based on feedback from the OCP terminal. This dynamic adjustment allows the system to maintain reliable off-resonance prevention through accurate real-time current monitoring and control, rather than relying on oversized passive components, thereby achieving reliability without increasing apparatus size.
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 improves overcurrent detection accuracy and reduces the size of the power supply apparatus while maintaining stable operation across varying input AC voltages, preventing off-resonance phenomena and minimizing the need for larger components.
Implementation Method 1
a resonance capacitor 108 connected to the other end of the primary winding 116... a control device 506 that controls the on and off periods of the switching units 106, 107 so as to resonate the primary winding 116 and the resonance capacitor 108 to output a DC voltage
Data Source
AI summary
A power supply apparatus includes a transformer and a switching unit that causes two switching elements connected in series to drive the primary winding of the transformer. A detection unit detects current flowing on the primary side of the transformer and outputs a voltage corresponding to the detected current. A correction unit corrects the voltage output from the detection unit into a voltage proportional to a variation of an input voltage input into the primary side of the transformer A nonlinear correction unit corrects the corrected voltage corrected by the correction unit to be nonlinear independently of variation in the input voltage.