Current Controlled Synchronous Rectifier Drive Circuit
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Solution Overview
Problem
Current drive synchronous rectifying technology faces issues such as high power consumption, complex circuitry, low working frequency, and difficulty in control, which hinder its application due to the expensive and complicated nature of existing current transducer designs with multiple windings.
Innovation Solution
A current controlled synchronous rectifying drive circuit with a simplified current transducer having a single secondary winding, a signal shaping and reset circuit to convert current signals into voltage pulses, and a push-pull power amplifying circuit to drive the synchronous rectifier, along with a drive self-bias circuit to regulate energy and reduce power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a current transducer with multiple windings is used for energy feedback, then the synchronous rectifier can be driven, but the cost increases and the manufacturing process becomes complicated
Solution Approach 1:
The patent divides the current transducer into separate functional components: a simple current sensing winding for detection and a separate drive winding for providing drive current. This segmentation allows each component to be optimized independently, reducing overall complexity while maintaining drive capability.
Solution Approach 2:
The patent makes the drive winding serve dual purposes: it provides the drive current for the synchronous rectifier and simultaneously serves as the energy feedback path. This multi-functionality eliminates the need for separate energy feedback windings, reducing the number of components and simplifying the manufacturing process.
2Device complexity
If voltage drive mode is used, then the circuit is simple, but the drive signal is influenced by input voltage and circulating current problems occur
Solution Approach 1:
The patent implements current-mode control with feedback from the current transducer sensing winding. The sensed current signal is processed through a control circuit that generates a stable drive signal independent of input voltage variations. This feedback mechanism prevents circulating currents by ensuring proper timing and magnitude control of the drive signal.
Solution Approach 2:
The patent replaces voltage-driven operation with current-driven operation. Instead of using voltage signals that are susceptible to input variations, the system uses current sensing and current-mode control, which provides inherent stability and immunity to voltage fluctuations and circulating current issues.
3Reliability
If prior art current drive technology is used, then synchronous rectification is achieved, but power consumption is high and working frequency is low
Solution Approach 1:
The patent employs pulse-width modulation (PWM) technique where the drive signal is applied in periodic pulses synchronized with the current waveform. The drive transistor is turned on only during the necessary intervals when current is flowing, rather than being continuously on. This periodic action significantly reduces power consumption while maintaining effective synchronous rectification.
Solution Approach 2:
The patent implements dynamic control where the drive signal timing and duration are adjusted based on the instantaneous current conditions. The drive circuit responds dynamically to the sensed current signal, extending the on-time during high current periods and reducing it during low current periods. This dynamic adaptation optimizes power consumption across varying load conditions while maintaining rectification effectiveness.
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 enhances efficiency, reduces power consumption, and simplifies the circuit structure, making it more cost-effective and adaptable to various topologies, while improving light load efficiency and reducing costs.
Implementation Method 1
a current transducer ST having a primary winding connected in series with a synchronous rectifier SR and having a secondary winding to detect a current signal of a synchronous rectifier SR
Data Source
AI summary
A current controlled synchronous rectifying drive circuit including a current transducer ST having a primary winding connected in series with a synchronous rectifier SR and having a secondary winding to detect a current signal of a synchronous rectifier SR, a signal shaping and reset circuit connected to the secondary winding of the current transducer ST to convert the synchronous rectifier SR's current signal into a voltage signal and shapes it into a pulse signal, a push-pull power amplifying circuit having an input end connected to the signal shaping and reset circuit and an output end connected to a gate of the synchronous rectifier SR to amplify a drive signal generated by the signal shaping and reset circuit to drive the synchronous rectifier SR, and a drive self-bias drive circuit having an input end connected to the secondary winding of the current transducer ST and an output end connected to the push-pull power amplifying circuit to store energy from the current transducer ST to generate a voltage source.