I want to open this thread and invite people to
help refine step on tuning resonance or stopping power reflection
we know stan stated 18 ohms etc
Using a Vector Network Analyzer (VNA) like the Nano VNA to optimize your voltrolysis nano bubble water fuel cell setup involves understanding how to measure and adjust for impedance mismatches to minimize power reflection. Here's a step-by-step guide on how you could approach this:
Step 1: Understanding Your Setup
Voltrolysis Cell: Your cell acts as a capacitor where water serves as the dielectric.
LC Tank Circuit: This includes your water cell (capacitor) and possibly an inductor forming an LC tank circuit which could resonate at your PWM frequency.
PWM and Choke: You're using Pulse Width Modulation at 5 kHz, with a bifilar ballast choke to further control current, and a blocking diode to prevent reverse current flow.
Step 2: Connecting the VNA Nano
Safety First: Ensure all power is disconnected before connecting anything. Always handle the VNA with care as it's sensitive to static electricity.
Connection Points:
Direct to Cell: Connect the VNA's test port directly to the points where your PWM signal enters the cell. You might need to temporarily disconnect or bypass some components (like the choke or diode) to get a direct measurement. Use coaxial cables to maintain signal integrity.
Calibration: Before connecting to the cell, calibrate your VNA. Use the open, short, and load standards provided with your VNA or calibration kit to perform a full one-port calibration at the point where you'll connect to the cell.
Step 3: Measuring Impedance and Reflections
S-Parameter Measurement: Set your VNA to measure S11 (reflection coefficient), which indicates how much power is reflected back due to impedance mismatch.
Frequency Sweep: Sweep the frequency around your PWM frequency (5 kHz) to see how the cell behaves across a small bandwidth. Look for dips or peaks in the S11 graph, which indicate resonance or significant impedance changes.
Identify Reflection: A high S11 value indicates significant reflection. You're looking for the point where S11 is minimized, which shows where your cell matches the impedance of your source (the PWM circuit).
Step 4: Tuning the LC Tank for Minimum Reflection
Adjusting Capacitance and Inductance:
Capacitance: If your water acts as a capacitor, changing the electrode spacing or the water composition might alter capacitance. However, this is less practical for tuning during operation.
Inductance: Adjust the inductance by either adding or removing turns in your inductor (if possible) or changing the inductance of your bifilar choke. Aim to tune the resonance frequency of your LC tank to match your PWM frequency for minimal reflection.
Iterative Tuning:
Make small adjustments to your choke or if possible, to the setup around the cell.
Re-measure with the VNA after each change to see if S11 decreases at your target frequency. This might involve some trial and error.
LC Resonance: The goal is to match the impedance of your cell to the impedance of your PWM circuit at 5 kHz. When your LC tank resonates at this frequency, you'll see a sharp decrease in S11, indicating less reflection and thus better power transfer into the cell's dielectric barrier discharge (DBD).
Step 5: Final Checks
Monitor Efficiency: After tuning, observe the performance of your cell. Look for increased gas production or reduced power consumption as signs of improved efficiency.
Recheck with VNA: After operational changes, recheck with the VNA to ensure your adjustments still hold for optimal performance.
Notes:
Practicality: This setup might require some custom engineering, especially since voltrolysis setups can vary widely in design and practical application.
Safety and Equipment: Always ensure your equipment can handle the voltage and frequency you're working with. High voltages from voltrolysis can be dangerous.
Component Quality: Ensure all components, particularly the choke and diode, are suitable for the frequencies and currents involved.
This process involves careful measurement, adjustment, and possibly several iterations to achieve maximum power efficiency into the DBD barrier of your cell. Remember, the exact steps might vary based on your specific setup's characteristics.