Switching Power Supply With Pulse Transformer Control
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Solution Overview
Problem
Resonant-type switching power supply apparatuses face challenges in miniaturization and efficiency due to complex circuit configurations and the inability to efficiently adjust switching frequency in response to input voltage or load changes, leading to increased power loss and size.
Innovation Solution
A compact switching power supply apparatus with a simple circuit configuration, utilizing a first and second switching circuit controlled by DC and AC voltage control circuits respectively, with a transformer and driving windings to generate voltages proportional to the primary winding, allowing for zero voltage switching and efficient operation by controlling the ON period of the switching elements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If resonant-type switching power supply apparatus uses AC voltage control circuits for switching elements, then switching frequency can be adjusted, but circuit configuration becomes complex and miniaturization becomes difficult
Solution Approach 1:
The patent introduces a pulse transformer as an intermediary component to transfer control signals from the primary side to the secondary side. This allows the control circuits to remain on the primary side where they can operate with stable DC voltage, while still controlling switching elements on the secondary side, thus avoiding the complexity of AC voltage control circuits.
Solution Approach 2:
The control system is divided into primary side control circuits and secondary side switching elements, with signal transmission separated through the pulse transformer. This segmentation allows each part to be optimized independently - control circuits use simple DC operation while switching elements respond to transmitted pulse signals.
2Ease of operation
If switching elements are controlled by AC voltage circuits, then switching operation can be achieved, but power loss increases and efficiency decreases
Solution Approach 1:
The patent replaces AC voltage-based control with DC voltage-based control using pulse width modulation. The DC control voltage is converted to pulse signals through the pulse transformer, providing more efficient switching control with reduced power loss compared to AC voltage control methods.
3Reliability
If complex control circuits are used for each switching element, then precise control is achieved, but circuit integration and miniaturization become difficult
Solution Approach 1:
The patent employs a universal control approach where a single control circuit architecture can manage multiple switching elements through the pulse transformer. The control circuits generate standardized pulse signals that can control different switching elements, reducing the need for individual complex control circuits for each element and enabling better integration and miniaturization.
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 enables efficient operation with reduced switching losses, miniaturization, and cost reduction by maintaining a constant driving voltage, preventing excessive current, and allowing arbitrary ON period control of switching elements, enhancing reliability and efficiency.
Implementation Method 1
a transformer including a primary winding, a secondary winding, a first driving winding, and a second driving winding, the secondary winding being connected to a first rectifying and smoothing circuit, the first and second driving windings each generating a voltage substantially proportional to a voltage of the primary winding
Data Source
AI summary
In a switching power supply apparatus, an inductor, a transformer, a first switching circuit, a second switching circuit, and a capacitor are connected to each other so that a first switching element and a second switching element can be alternately turned on and off, an output can be obtained from a secondary winding of the transformer, and an output voltage can be controlled by controlling the ON period of the first switching element. The secondary winding of the transformer is connected to a first rectifying and smoothing circuit. A first control circuit is configured to operate using a DC voltage supplied from a second rectifying and smoothing circuit. After the second switching element has been turned on, the second switching element is forcefully turned off at a predetermined time set by a turn-off circuit included in a second control circuit that operates using an AC voltage.