dword1511 / stm32-hbctl

STM32-based half-bridge controller

STM32-based half-bridge controller

This firmware code uses an STM32F042 MCU to generate waveform for a STMicro L6498 half-bridge driver, which drives the MOSFETs in the inverter.

This particular inverter delivers 1 MHz AC current for our capacitive power transfer (CPT) project. It has onboard buttons allowing us to cycle through 1 MHz +/- 100 kHz, with a few kHz of resolution. It also has USB for ISP/DFU.

Unusual things this firmware does:

• Using HSI48 trimming in conjunction with timer prescaler to deliver a resolution of a few kHz across a large frequency range.
• Using a generic timer (rather than the advanced one) to generate complementary waveforms with dead time.

General Build Instructions

You will need the following packages (Debian/Ubuntu):

• build-essential
• gcc-arm-none-eabi
• git
• dfu-util

The firmware can be loaded via USB DFU. However, you can also flash and debug via SWD. To do so, install the following package:

• stlink-tools
• gdb-multiarch

This project uses libopencm3. It will be automatically checked out during the building process. To build the firmware, run make. To flash it, hold the ISP/USR button on the board, connect the board to USB, and then run make flash-dfu.

Special Directions for CPT

Please be aware of the high voltage, especially at matching network's output.

Connect the inverter to the matching network first. Do not power on the inverter without any load. Connect 12 V DC power to the 12 V port with a 4 mm banana test lead. Connect a variable DC power source to the HV port. Connect the ground together to GND.

Power the board on and observe the LEDs starting to flash. Use the ISP/USR button to enable the half-bridge. Then use the same button to cycle through frequencies. The matching network reaches resonance when the output voltage peaks. Bridge current can be monitored by attaching an oscilloscope probe to the CSP pin.

Publication

This project was part of the following work. Please kindly consider citing the paper as shown:

@inproceedings{Capttery,
 author = {Zhang, Chi and Kumar, Sidharth and Bharadia, Dinesh},
 title = {{Capttery: Scalable Battery-like Room-level Wireless Power}},
 booktitle = {Proc. of ACM MobiSys},
 year = {2019},
}