Experimental

Overview

Two boards:

  • Control board: Voltage/current sensing, isolation, communications (CAN/RS-232), debugging (DAC outputs to oscilloscope), etc.
  • Power board: MOSFETs/IGBTs, gate drivers, isolation

Sensing Solution

ADC: 1 x ADS8568

  • 8 channel, 16 bit ADC.
  • Voltage supply requirements?
  • Input filtering?
  • Serial or parallel comms?

Voltage conditioning: Quad precision op-amp?

  • Is this even needed?
  • Unity buffer?
  • Anti-aliasing filter?
  • Voltage supply requirements?
  • Series resistor with ADC to ensure it never draws too much power?

Voltage isolation: 4 x ISO124

  • Voltage supply requirements?
  • Input filtering?
  • Output filtering?

Current sense resistor: 4 x Vishay WSHM28185L000FEB

  • 5000 µohm, 7 W, ± 1%, 2818 [7146 Metric]

Current isolation: 4 x AMC1100/ACPL-C790

  • Voltage supply requirements?
  • Input filtering?
  • Output filtering?

Current conditioning: Quad precision op-amp?

  • Op-amp circuit for amplification
  • Anti-aliasing filter?
  • Voltage supply requirements?
  • Series resistor with ADC to ensure it never draws too much power?

Other:

  • LEDs for 5V, 15V, -15V supplies
  • Zener diode to limit voltages

Or I could use ISO124 with current sensing too, with a current shunt analog output circuit to take care of the gain! Then the ISO124, anti-aliasing filter, and input to ADC are identical for both voltage and current measurement.

PCB Design and Manufacture

The PCBs are designed using Altium Designer. This is quite expensive, so CadSoft EAGLE is a great alternative.

The PCBs are manufactured by Eurocircuits.

Solar Photovoltaics

Options include:

  • Actual solar panels installed
  • Solar PV emulator (should be panel emulators rather than array emulators due to microconverter usage)
  • Programmable DC power supply to emulate the entire panel array + converters system, (constant voltage output with variable current depending on total input power)
  • Small programmable DC power supplies fed through isolation transformers. These will emulate each solar panel
  • Build own solar PV emulator. Options:
    • Isolation transformer feeding off-the-shelf/custom programmable AC-DC converter, with controller to vary the voltage output to act as a current source on panel’s I-V curve, for every panel.
    • Rectifier (with optional step-down transformer), followed by isolated DC-DC converters which are controlled to act as a current source on panel’s IV curve. This has the advantage of only 1 isolation transformer/AC connection needed, as all DC-DC converters are fed from the same DC bus.