Bidirectional DC-DC Converter Control for Synchronous Rectification
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Solution Overview
Problem
Existing bidirectional DC-DC converters face challenges in achieving high efficiency through synchronous rectification due to increased cost and circuit area requirements, particularly when using GaN switching elements and external Schottky barrier diodes.
Innovation Solution
A power converter device incorporating a capacitor, switching units, a reactor, an isolated transformer, and a controller with phase-shift and logic operation units to generate switching control signals, enabling synchronous rectification without the need for external Schottky barrier diodes or high-performance CPUs, thereby minimizing cost and circuit area.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If an external Schottky barrier diode is provided in parallel with the switching element to achieve high efficiency, then the conduction loss is reduced, but the cost and circuit surface area increase
Solution Approach 1:
The invention extracts and eliminates the external Schottky barrier diode from the circuit by implementing synchronous rectification using the body diode of the switching element itself, thereby reducing circuit surface area while maintaining low conduction loss through optimized switching control
Solution Approach 2:
The switching element is made to serve multiple functions: both as a switching device and as a rectification device through its body diode, eliminating the need for separate external diodes and reducing overall circuit component count and area
2Loss of energy
If synchronous rectification is implemented to achieve high efficiency, then conduction loss is reduced, but instantaneous current measurements at high speed and high precision are required, increasing cost
Solution Approach 1:
The invention implements partial synchronous rectification by controlling switching elements to conduct during specific intervals when current magnitude and direction are favorable, rather than requiring continuous precise measurement and control, thereby achieving significant efficiency improvement without demanding high-speed precision measurement systems
Solution Approach 2:
The control unit uses feedback from voltage and current sensor readings to dynamically adjust switching element operation, enabling efficient synchronous rectification through adaptive control rather than requiring continuous high-speed precision measurements
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 allows for efficient synchronous rectification in bidirectional DC-DC converters, reducing costs and circuit area while maintaining high efficiency, as demonstrated by the ability to generate control signals for switching elements via phase shift and logic operations.
Implementation Method 1
a capacitor (C1) for smoothing a voltage entering therein
Implementation Method 2
an isolated transformer (TR)
Implementation Method 3
a parasitic capacitance of the switching element
Data Source
AI summary
A power converter includes a capacitor for smoothing a voltage entering therein, first and second switching units, a reactor, an isolated transformer, a second capacitor, and a controller for controlling the switching of the first and second switching units. The controller converts direct-current power to alternating-current power via the reactor and the isolated transformer and converts the alternating-current power to direct-current power via the second capacitor. The controller includes a phase-shift operation unit for taking at least any of first switching control signals as a reference signal and for calculating a phase shift that shifts the phase of the reference signal, as well as a logic operation unit for performing a logic operation that takes the signal resulting from shifting the phase of the reference signal by exactly the phase shift as input and for outputting a second switching control signal.