HF Resonant Circuit Igniter Control via Zero-Crossing Detection
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Solution Overview
Problem
Existing methods for igniting a fuel-air mixture in internal combustion engines using high-frequency corona discharges face challenges with resonant frequency shifts due to load changes, temperature variations, and component drift, leading to control deviations and increased switching losses.
Innovation Solution
A method employing a DC-AC inverter with a control circuit that generates current pulses based on zero passages in the HF resonant circuit, allowing precise control of the resonant frequency without a phase control loop, thereby reducing deviations and switching losses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a phase control loop is used to control the resonant frequency, then the resonant frequency can be adjusted, but control deviations and overshoots occur due to temperature drift and voltage noise
Solution Approach 1:
The patent removes the phase control loop from the system entirely. Instead of using a complex feedback control mechanism that is susceptible to temperature drift and voltage noise, the invention extracts the frequency control function and replaces it with a simpler zero-crossing detection method that directly controls the resonant frequency without introducing additional control deviations and overshoots.
Solution Approach 2:
The patent replaces the mechanical/electronic phase control loop system with a digital zero-crossing detection system. By detecting the zero-crossing points of the current waveform and using these to trigger switching actions, the system achieves frequency control without the thermal and electrical interference that affect traditional phase control loops.
2Adaptability or versatility
If a phase control loop is used to control the resonant frequency, then the resonant frequency can be adjusted, but switching losses increase when phase shift increases
Solution Approach 1:
The patent removes the phase control loop that causes increased switching losses. By directly controlling the resonant frequency through zero-crossing detection without introducing additional phase shifts, the system avoids the energy losses associated with frequent switching operations during phase adjustment.
Solution Approach 2:
The patent uses periodic zero-crossing detection to control the resonant frequency. By synchronizing switching actions with the natural zero-crossing points of the resonant current, the system achieves efficient frequency control without the additional switching losses that would result from continuous phase adjustment operations.
3Adaptability or versatility
If the resonant frequency is controlled by measuring phase shift, then frequency control is achieved, but control time increases leading to slower response
Solution Approach 1:
The patent removes the phase shift measurement and control process entirely. By directly detecting zero-crossing points and using these to immediately trigger switching actions, the system eliminates the time-consuming phase measurement and adjustment operations while achieving the same frequency control objective.
Solution Approach 2:
The patent performs preliminary zero-crossing detection and uses these pre-detected points to immediately trigger the next switching action. This preliminary detection approach eliminates the need for continuous phase measurement and adjustment, significantly reducing control time and improving system response speed.
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 enables quicker and more precise control of the resonant frequency, minimizing control deviations and switching losses, and simplifies the electric circuit structure, reducing manufacturing costs and ensuring efficient ignition.
Implementation Method 1
A method employs a DC-AC inverter with a control circuit that generates current pulses based on zero passages in the HF resonant circuit
Implementation Method 2
an HF resonant circuit which is energized by means of a high-frequency corona discharge generated in the combustion chamber
Implementation Method 3
The frequency of the alternating current voltage that is supplied by the transformer and energizes the resonant circuit is controlled such that it is as close to the resonant frequency of the resonant circuit as possible. In case there is resonance, current and voltage are in phase in a series resonant circuit
Data Source
AI summary
The invention relates to a method for energizing an HF resonant circuit which contains an igniter as a component for igniting a fuel-air mixture in a combustion chamber of an internal combustion engine by means of a corona discharge, wherein the igniter comprises an ignition electrode and an insulator surrounding the ignition electrode, by means of a DC-AC inverter which is excited by successive current pulses which each last while a switch controlled by a control circuit is in its conducting switching state. It is provided according to the invention that the switch is actuated when an instantaneous value of an alternating current or an alternating current voltage excited in the HF resonant circuit falls below a first switching threshold (A−, B−, C−) and the switch s actuated when the instantaneous value of the alternating current or the alternating current voltage excited in the HF resonant circuit exceeds a second switching threshold (A+, B+, C+).