The goal of this project is to create a full featured precision positioning servo drive board. It has been especially designed for 3 phase AC servomotors but it will also handle BLDC or brushed DC motors as well. The goal is no less than industrial quality drive which utilizes the most efficient control methods like Flux Vector Control, PID feedback loop with feedforward branches.

Target power range is about 1 kW maximum continuous output power. The board has differential encoder interface to deal with high resolution quadrature encoders. The board can be equipped with varying MOSFET/IGBT devices to adapt on different voltage ranges.

Currently the drive is in heavy devepoment phase. The schematcs and layout are mostly finished and I already have a proto board for software development. The present status of the software is where it successfully drives AC servo as positioning actuator.

I finally had time to finish the first prototype board. So far very little changes were necessary to make it functional.

I already have some written software for the drive. It already implements flux vector control and positioning PID loop. So far everything is looking good!

Preliminary listing of planned features

• Fast step/dir control interface
• Step multiplier
• Sinusoidal flux vector control algorithm
• Standard PID positioning with feedforward and anti-windup
• 24-200 Vdc input voltage, ~10 Amps continuous output drive
• Support for BLDC, BLAC, and brush DC servos
• Phase positioning without hall sensors
• Differential encoder input
• PC based tuning via serial port
• Firmware upgrading via serial port

Additionally considered features

• PWM and/or analog input for torque/velocity mode
• Step left/step right input mode utilizing step/dir ports
• SPI or RS232 control protocol

Things that could be researched and possibly provided via firmware update

• Stepper support
• Autotuning at some degree

I'm researching the possibility of producing a small batch of drives industrially. Please see my CNCzone thread with poll here.

If you don't have CNCzone account to vote, you can also express your interest via email.

Your opinion matters.

The photo shows a new current sensing board that is based on a differential op-amp circuit. The goal is to achieve a highly accurate and very low noise sensing for the next servo drive prototype.

I'm going to hook this on the first proto board and see how it performs.

I'm switching from dsPIC to Freescale DSC's. The photo shows 56F8300 demonstration board controlling the existing drive prototype (thanks for borrowing the board Hannu!). The new current sensing circuit is also in place.

Porting current drive firmware to the new platform should be easy since it's designed portability in mind.

It's been too long time since last update. It has been more fun to tweak with servos than update home page. Sorry :)

For more detailed steps of development, please see a CNCzone discussion about this drive.

After many prototypes and hundreds/thousands of hours development the drive has finally become to point where I can declare it to be ready for serious use.

Couple of months ago me and one of my friends started running a company to manufacture and develop these drives further. For details please see our web site of Granite Devices.

Our goal is no less than to deliver the best drives for CNC use for a reasonable cost. Technical details can be found here.