Our hardware was designed to interface with the STM32F3 Discovery board, and has three main functions: a power path, current sensing, and user interface.  

 

Power Path:

Our power path is comprised of three half-bridge circuits, with IRFB4332 MOSFETs for switches and an IRS21834 for a gate driver. The half bridges are used in the buck configuration, so a high-voltage input is required for large-amplitude outputs. Each half bridge module can be used to drive a motor phase, and all modules are independently controlled. Bootstrapping allows the high side gate driver to function when the switching node goes high, and each phase has a local decoupling capacitor on the high voltage line.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Current Sensing:

Kelvin-connection current sense resistors are placed along the power path of each phase. Differential amplifiers relay the voltage across the resistor back to the microcontroller for processing. There is also a current sense resistor to measure the total current of all phases, and circuitry to measure the voltage across one of the phases to supplement the phase current data. Each current sense resistor has the option to be shunted with a capacitor for filtering, and each instrumentation amplifier has decoupling capacitors on their power supplies.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

User Interface:

Our circuit supports a user interface of four buttons (nominally paired as forward/reverse and speed up/speed down) as well as an LCD for displaying current motor properties to a user.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

We prototyped the power path using the lab half bridge modules in order to allow for embedded code development while waiting for the boards to get in from the board house. For that purpose, the setup worked admirably, but it was too difficult to work with (too many closely-spaced cables) for extended use.