Photon 1

Description

The Photon MPPT is a boost mode Solar Array Maximum Point Power Tracker (MPPT) designed primarily for solar powered car racing, specifically for cars entering the World Solar Challenge and the American Solar Challenge. It has been optimized for the new generation of lower voltage, higher current silicon solar arrays and it has been specifically optimized to convert series strings of unmodified SunPower™ solar cells.

Features

• High Efficiency
  • MPPT designed for the highest possible efficiency across the entire operating range while weighing only 549 grams.
• Closed loop
  • MPPT will track any array that it's connected to without additional configuration. It's closed loop tracking algorithm will find and hold the maximum power point in varying conditions.
• Wide Input Range - Design Flexibility
  • Designed for lower voltage, high efficiency silicon arrays. Architecture allows a 16 to 1 ratio between the array voltage and the battery voltage, allowing designs that use very small subarrays.
• Optimized for Modern Solar Cars
  • Maximum efficiency point chosen for ~6A cells, matching common configurations
  • Hardware overvoltage protection aligned with common motor controller specifications to reduce risk of damage and to maximize total system reliability.
  • Powered by 12V vehicle power, the MPPT turns on and shuts off with the rest of your electrical system
• Telemetry
  • Telemetry allows remote monitoring of array performance
  • Tested with 125kbit and 500kbit CAN busses
  • Easily parsed CAN messages, the MPPT does the math for you in converting to useful units.
  • Configurable as automatically reporting at a programmed frequency or RTR based polling for data.

Specifications

Efficiency

Efficiency over a wide range of currents can be estimated by the following equation:

Efficiency = 0.9948 - (0.0052 * BoostRatio)

where BoostRatio = VBattery / VArray

Connectors and Switches

• CAN BUS Side
  • CAN BUS Conectors
    • Connector
    • Pin 1 - CAN V+ (10-16VDC)
    • Pin 2 - CAN BUS H
    • Pin 3 - CAN Bus L
    • Pin 4 - CAN GND (Return for CAN V+)
      • Note: CAN Bus is galvanically isolated from Battery and Array terminals
  • DISABLE Connector
    • Connector
    • Pin 1 - CAN GND
    • Pin 2 - DISABLE
      • Pin has internal pullup. No connection (Floating) will enable MPPT. Connecting to CAN GND will disable MPPT
  • LEDs
    • Blue - Output Enabled - When this is on, the power converter circuits are running
    • Green - Heartbeat - This will blink to show that the MPPT's logic is running
    • Yellow - Status - This will blink during curve tracing and when the MPPT is operating in constant voltage mode
    • Red - Error - This indicated an error condition is present. Error code is flashed.
  • CHANNEL
    • These four switches encode the CAN address offset for the particular unit.
    • A down switch encodes a 0 and an up switch encodes a 1
    • The four of them together encode a 0x00 to 0x0F channel address offset. For example:
      • All 4 are down, 0x00 is the channel number.
      • Just switch 0 is up, 0x01 is the channel number.
      • All 4 are up, 0x0F is the channel number.

• Array and Battery Connection
  • Connector
  • Pin 1 - Output Battery Negative
  • Pin 2 - Output Battery Positive
  • Pin 3 - Input Array Positive
  • Pin 4 - Input Array Negative

Firmware

Guide for loading firmware

Changelog

• HW Version 1.5
  • Small changes for manufacturability
• HW Version 1.4
  • Small changes for manufacturability
• HW Version 1.3
  • Initial Release