Intense Brushless DC Stage Brings More E-Bike Power

[ZombieSS] wrote in to share the latest iteration of his new open hardware Brushless DC motor high power output stage posted on the Endless-sphere forums. The thread is a gold mine of useful information on designing, building and debugging high power electronics and the whole thing is worth reading. This includes the story of issues he faced with common mode noise picked up by the probe leads on his Rigol, which sidetracked the project for a while.

ebikeWe’ve covered various ebike hacks before, but the guys at endless sphere appear to be developing a number of solid open hardware designs in this area. This includes the Lebowski controller which [ZombieSS] used in conjunction with his design.

He has installed the controller and output stage on his electric bike, and you can see one of the first test runs in the video below. We look forward to hearing more from the awesome hackers at Endless sphere!

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Driving A Brushless DC Motor Sloooooooowly

Driving a brushless DC (gimbal) motor can be a pain in the transistors. [Ignas] has written up a nice article not only explaining how to do just this with an Arduino, but also explaining a little bit on how the process works. He uses a L6234 Three Phase Motor Driver, but points out that there are other ways to interface the BLDC motor with the Arduino.

warningA warning is warranted – this is not for the faint of heart. You can easily destroy your microcontroller if you’re not careful. [Ignas] added several current limiting resistors and capacitors as advised in the application note (PDF warning) to keep things safe.

Everything worked well at high speeds, but for slower speeds the motor was choppy. [Ingus] solved this riddle by changing over to a sine wave to drive the motor. Instead of making the Arduino calculate the wave, he used a look up table.

Be sure to check out his blog for full source and schematics. There is also a video demonstrating just how slow he can make the motor move below.

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Brushless Motor Controller Shield for Arduino

Brushless motors are ubiquitous in RC applications and robotics, but are usually driven with low-cost motor controllers that have to be controlled with RC-style PWM signals and don’t allow for much customization. While there are a couple of open-source brushless drivers already available, [neuromancer2701] created his own brushless motor controller on an Arduino shield.

[neuromancer2701]’s shield is a sensorless design, which means it uses the back-EMF of the motor for feedback rather than hall effect sensors mounted on the motor. It may seem strange to leave those sensors unused but this allows for less expensive sensorless motors to work with the system. It also uses discrete FETs instead of integrated driver ICs, similar to other designs we have covered. Although he is still working on the back-EMF sensing in his firmware, the shield successfully drives a motor in open-loop mode.

The motor controller is commanded over the Arduino’s serial interface, and will support a serial interface to ROS (Robot Operating System) in the future. This shield could be a good alternative to hobby RC controllers for robots that need a customizable open-source motor controller. The PCB design and source code are available on GitHub.

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Brushless DC Motor Used For High Speed CNC Spindle

Brushless DC Motor CNC Spindle

Brushless DC motors are common place in RC Vehicles. They are small, light, fast and can be inexpensive. [Raynerd] wanted a new spindle for his CNC machine and thought that a brushless DC motor would be a great platform to build from.

[Raynerd] started with an off the shelf motor that had an 8mm shaft. This shaft size was important because the motor shaft was to be replaced with an ER16 collet arbor of the same size. A collet is a device used to hold cutting tools by collapsing a segmented ring around the tool. Collets allows for quick tool changes while providing a strong clamping force. ER16 is a designation of one of many collet standards.

The main housing was machined out of aluminum specifically for this project. This housing holds two radial load ball bearings that support the new rotating collet arbor. There’s another bearing in this assembly, a thrust washer this time, that keeps the arbor from moving axially in the housing.

The 12 volt output of a standard ATX power supply was used to power the system for testing purposes. A general RC Vehicle electronic speed control and a servo tester work in conjunction to manually regulate the spindle speed. Check out the bench test video and an exploded photo after the break.

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e-volo VC200 Makes Maiden Flight. Flying Cars Incoming

The e-volo VC200 has made it’s maiden unmanned flight. Does the craft above look a bit familiar? We first reported on the e-volo team back in 2011. Things have been going great for the team since then. They’ve created an 18 motor (Octadecacopter?) prototype dubbed the VC200. The group has taken a smart approach to building their craft. Rather than try to keep everything in-house, they’ve created a network by partnering with a number of companies who are experts in their fields. A sailplane company laid up the carbon fiber composite frame for the EC200. Junkers Profly, a German aviation company, developed a ballistic parachute system in case something goes wrong in flight.

From the outside, the VC200 looks like a grown up version of the Quadcopters we’ve seen here on Hackaday. Even the control system used for the test flight looks like a modified Radio Control Transmitter. The motors are outrunner brushless motors. Props are carbon fiber. We’re hoping the control system is a bit more evolved (and redundant) than the systems used in R/C quads though. Just like in smaller scale models, batteries are still the limiting factor. The VC200 will only fly for about 20 minutes on a charge. However, e-volo says that new technology should allow it to extend that time to around an hour. Not very much for a cross country flight, but plenty to pioneer a new type of aircraft. Where do we sign for the beta program?

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