Switching power supply device and charging system
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Solution Overview
Problem
Existing switching power supply devices require current detection on the primary side to control the synchronous rectifier circuit on the secondary side, complicating the control process.
Innovation Solution
A switching power supply device with a transformer, bridge circuit, resonant circuit, and synchronous rectifier circuit, where the control unit fixes the frequency of switching elements on the primary side and provides phase differences to control the synchronous rectifier circuit based on predetermined current thresholds without detecting primary side current values or times.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If current detection on the primary side is performed to control the synchronous rectifier circuit, then the synchronous rectifier can be controlled accurately, but the control process becomes complicated
Solution Approach 1:
The patent extracts the current detection function from the primary side control system and relocates it to the secondary side where the synchronous rectifier circuit is located. By detecting the current on the secondary side and using this information to control the synchronous rectifier switching, the system eliminates the need for complex primary side current detection and timing control, thereby simplifying the overall control process while maintaining accurate control of the synchronous rectifier.
2Ease of operation
If primary side current value and time detection is implemented, then synchronous rectifier control is achieved, but the system requires complex detection mechanisms
Solution Approach 1:
Instead of detecting the primary side current and using that information to control the secondary side synchronous rectifier (the conventional approach), the patent inverts the control strategy by detecting the secondary side current and using this detection to control the synchronous rectifier switching. This inversion eliminates the need for complex primary side current detection and timing synchronization, making the system easier to operate with simpler detection requirements.
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
Enables the synchronous rectifier circuit on the secondary side to be turned on and off without detecting primary side current values or times, preventing overcurrent and overcharge by performing constant current and constant voltage charging.
Implementation Method 1
a resonant circuit connected between a primary side of the transformer and an output side of the bridge circuit
Implementation Method 2
a transformer; a bridge circuit including a first switching element, a second switching element, a third switching element, and a fourth switching element
Implementation Method 3
a synchronous rectifier circuit connected to the secondary side of the transformer
Data Source
AI summary
A control unit controls a synchronous rectifier circuit to rectify a current flowing through a secondary side of a transformer at a timing when an absolute value of a first current flowing through a primary side of the transformer in a first direction when a first switching element and a second switching element are turned on or at a timing when the absolute value of a second current flowing through the primary side of the transformer in a second direction opposite to the first direction when a third switching element and a fourth switching element are turned on is equal to or greater than a predetermined threshold.