Accelerated Systems Inc. Introduces New Line of BAC Electric Motor Controllers at the Taipei Cycle Show 2012

I just joined the group and wanted to follow up on this post with a little information about Accelerated Systems Inc., and myself. I spent a few years in the controller industry and lurked on this forum for quite some time. I left the field for a few years but now I am back into EV controllers and, as you might guess from my user name, I work for ASI.

Accelerated Systems Inc. has history in the EV world going back over 20 years, and we bought Navitas Technologies a few years ago. Now we offer many of the Navitas controllers as well as the new BAC line of brushless DC controllers mentioned in the news release. Accelerated Systems is not a gigantic multinational company, but we do have some very solid and technically advanced controllers.

I look forward to spending some time here and hopefully providing some useful comments now and then.

Hi ASI guy,
How much is the BAC500?
That one looks appropriate for an eBike,
though I do not see a connection for a throttle,
only the "Thun sensor" and I wonder if that is
the crank sensor to detect pedals turning?
I like to have a Brushless controller with a
simple 5V thumb throttle input, if there is a
feedback onto LEDs about the battery SoC then
that is fine but not required.
The datasheet says sensorless while the
schematic shows the Hall sensors.
(I actually have these same 5 sensor wires
coming from my motor).
Can you explain how to get field weakening?
Thanks!

Thanks for your interest Cor. I am not an engineer, but I will do my best to answer all of your questions.

At this point, Accelerated Systems doesn't have end user pricing set up on the BAC line. Our main focus so far has been the OEM world. I can see in the near future that we will be setting up some dealers who will be able to provide pricing on single controllers and conversion kits.

Regarding the throttle, the BAC500 will operate either as a pedalec only (just the torque sensor) or with a resistive or Hall type throttle. The Thun sensor does detect the amount of torque applied via the pedals and lets the controller know how much power to put out when being used as a pedalec.

The BAC500 can operate with or without motor mounted Hall sensors, depending on the application.

Field weakening is a little trickier to explain. Since you cannot change the field strength on a standard BLDC motor, we use a special control algorithm to adjust the timing of the waveform applied to the stator windings. This can be used to advance the waveform which, when done properly, will reduce the back EMF and increase the speed of the motor while reducing torque. Hopefully I haven't messed that up too badly. There are some really good technical explanations of this on the web that can cover the topic far better if you are interested. Just Google "field weakening with brushless motor".

I hope this helps.