Synchronous Rectifier Digital Gate Control for Wireless Charging
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Solution Overview
Problem
Conventional synchronous rectifiers in wireless charging systems suffer from non-zero delays in switching operations, leading to undesirable 'on' bounces and reverse currents that negatively impact efficiency.
Innovation Solution
The implementation of digitally assisted gate control (DAGC) modules that account for signal processing and propagation delays to control the switching of FETs, minimizing 'on' bounces and reverse currents through digitally assisted 'switch on' and 'switch off' circuitry.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If conventional synchronous rectifiers are used with standard switching control, then the rectifier can operate with simple control circuitry, but non-zero delays in switching operations cause undesirable 'on' bounces and reverse currents that reduce efficiency
Solution Approach 1:
The patent applies preliminary action by predicting the ideal switching instant before it occurs. The controller calculates the ideal switching time based on known system parameters (inductance, current, voltage) and proactively commands the switch to turn on at this predicted instant, compensating for the inherent switching delay. This allows the system to achieve near-ideal efficiency without requiring complex real-time adjustment mechanisms.
Solution Approach 2:
The patent implements feedback by continuously monitoring the actual switching behavior and comparing it with the ideal switching waveform. The controller uses this feedback information to adjust the switching control signals in real-time, ensuring that the actual switching instant matches the ideal switching instant despite variations in operating conditions or component tolerances.
2Reliability
If switching operations are performed without delay compensation, then the control logic remains simple, but 'on' bounces and reverse currents occur during switching transitions
Solution Approach 1:
The controller pre-calculates the ideal switching instant using system parameters before the switching event occurs. This preliminary calculation accounts for the inherent switching delay, allowing the control system to command the switch to turn on at the correct time without requiring complex real-time adjustments during the switching transition itself.
3Productivity
If the switching instant is not precisely controlled, then the control system remains simple, but efficiency is reduced due to prolonged reverse current flow and 'on' bounces
Solution Approach 1:
The controller continuously monitors the switching waveform and compares it with the ideal switching pattern. Based on this feedback, the controller dynamically adjusts the switching control signals to maintain precise switching timing, ensuring that the actual switching instant matches the ideal switching instant even under varying operating conditions.
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
This approach significantly reduces the magnitude of 'on' bounces and reverse currents, enhancing the overall efficiency of the synchronous rectifier by ensuring timely switching of FETs.
Implementation Method 1
The TX and RX inductor coils 116 and 132 form an inductive interface 120 for wirelessly (i.e., magnetically) transferring power from the TX 110 to the RX 130 and communications signals between the TX and RX
Data Source
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AI summary
A synchronous rectifier converts an AC input into a DC output. The synchronous rectifier has four switches controlled by four switch control modules. Each switch is connected between a different AC component and either the DC output or ground. Each switch control module has digitally assisted "switch on" circuitry that detects "on" bounces in the corresponding AC component to control when to turn on the corresponding switch and digitally assisted "switch off" circuitry that detects "off" bounces in the AC component to control when to turn off the corresponding switch. The "switch on" circuitry has a digitally assisted comparator to detect threshold crossings in the AC component, and the "switch off" circuitry has a digitally assisted programmable delay cell to turn off the switch for a predetermined duration following each detected threshold crossing.