Synchronous Rectifier Switch Timing Control
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Solution Overview
Problem
Existing rectifier bridge circuits for motor vehicle generators face challenges in precisely controlling active switches to minimize power loss, which is complicated due to the need for synchronous operation with phase frequency, especially in variable operating states.
Innovation Solution
A method for calculating switch-on and switch-off times using a characteristic diagram or function that incorporates machine-specific parameters such as speed, excitation current, and generator voltage, allowing for simple and precise control signal generation without position sensors or high-precision analog circuits, enabling efficient synchronous rectification.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If active switches (MOSFET transistors) replace rectifier diodes to reduce power loss, then power loss is significantly reduced, but the control complexity and precision requirements increase due to synchronous operation needs
Solution Approach 1:
The system uses the generator's own phase voltages and operating parameters (speed, excitation current) to automatically determine switch-on and switch-off times through characteristic diagrams, eliminating the need for external position sensors or complex control algorithms. The rectifier system self-regulates based on its inherent electrical characteristics.
Solution Approach 2:
The invention utilizes changes in generator operating parameters (speed ng, excitation current IE, phase voltages U1-U3) to dynamically adjust the switching times of the active switches. By mapping these parameter changes to characteristic diagrams, the system adapts to variable operating states without increasing control complexity.
2Measurement precision
If characteristic diagrams with multiple input variables (speed, excitation current, voltage, angle) are used to calculate switch-on and switch-off times, then precision is improved, but device complexity increases
Solution Approach 1:
Characteristic diagrams are pre-calculated and stored for various operating conditions. During operation, the control device simply needs to identify the current operating point and retrieve the corresponding switching times from the pre-prepared diagrams, rather than performing complex real-time calculations.
Solution Approach 2:
The invention transitions from time-domain control to a parameter-space approach by using characteristic diagrams that map switching times as functions of multiple operating parameters (speed, excitation current, voltage). This dimensional transformation simplifies the control logic while maintaining precision.
Data Source
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AI summary
Disclosed is a rectifier bridge circuit for rectifying the phase voltage generated by a generator, comprising a positive half-bridge with multiple rectifier elements as well as a negative half-bridge with multiple rectifier elements. The rectifier elements each have a controllable switch with a diode that is connected in parallel. A triggering circuit is provided for switching the switches on/off. The switch-on time tSchalter ein soll and/or the switch-off time tSchalter aus soll of the switch is/are calculated on the basis of a characteristic diagram or a mathematical function.