January 21, 2017

Motor Dyno: The Talk-To-Everything Board, and Other Updates

Here's the Talk-To-Everything Board.  The idea is that I want to be able to plug arbitrary motor controllers into the motor dyno, and control them from the UI on the computer.  There's an FTDI chip for USB to serial, with a digital isolator and isolated DC-DC converter, so that the computer is electrically isolated from whatever motor controller gets plugged in.  My favourite STM32 is broken out to a CAN tranceiver, a small buck for 0-5V output, I2C, RC PWM, TTL Serial,  differential 5V serial (like RS422), and SPI.  Even if I don't end up ever using several of these, it wasn't much extra effort to break out more interfaces, so I figured I might as well.

I moved the 'Everything-Board, plus DAQ and other sensitive analog stuff into an aluminum box with shielded cables in, to fix some more noise problems.  I also now have a big LEM closed-loop hall current sensor for measuring the buck output current.

Here's a look at the current user interface.  Notice all the extra doodads for controlling some of the test-motor interfaces.  I've also added "Profile Mode", which takes in a csv series of speeds, buck voltages, and test-motor commands with time-stamps, and plays them back on the hardware.  This way I can easily automate cycles like efficiency maps.

I'm currently in the progress of designing a new buck converter from scratch, to replace the awful pile of Prius power electronics that is the current buck.  Progress is slow, because I have very little experience with analog electronics and hardware controls (for regulating the buck voltage and current).


  1. For the buck current feedback transducer, is that something like the LEM LF210?

    1. I'm using a big panel mount LEM similar to the LT 200-S.