3 Phase E-bike?

Electric Motors and Controllers
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dirtybagg
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3 Phase E-bike?

Post by dirtybagg » Mon Sep 11, 2017 1:21 am

I am new to this forum, and I'm an engineer, so there is likely some over-thinking going on. I'm really enjoying learning about the innovations coming form GRIN Technologies, but I'm wanting a little more clarity on some terminology. In the industrial world, the standard motor controller is a VFD or Variable Frequency Drive. The VFD delivers three phases of PWM DC power to an AC motor, and has common use in household appliances like the clothes washing machine, and it's what drives many modern E-cars. A few advantages of VFD control are:

1: a built-in gearing system (motor speed is tuned by frequency, which minimizes some limitations of gear reductions and motor winding configurations)
2: regenerative braking is included
3: VFD has favorable efficiency for stationary use, even after AC to DC inverter losses, which means even greater efficiency for mobile application as the battery is already supplying DC.

Is VFD-like control available for a Brushless motor? Is anybody making VFD e-bikes? What is implied by controller names like "Phase Runner"? three phases? What can an Engineer tinker with to make this all possible?

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amberwolf
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Re: 3 Phase E-bike?

Post by amberwolf » Mon Sep 11, 2017 1:31 am

Nearly all the brushless motors on bikes are 3-phase BLDC.

In this forum, there is a list of sticky threads that have quite a bit of info on ebike motors and controllers, how they work, etc. I'd recommend those as a first reading.

There is also a wiki, linked in threads at the top of every forum, that has some of the same info and more.

There's also dozens (hundreds) of motor and controller modification and repair threads with more detail on specific ones.

This search
https://endless-sphere.com/forums/searc ... mit=Search
finds a number of posts that mention VFD, don't know if any of them cover the info you're after.

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spinningmagnets
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Re: 3 Phase E-bike?

Post by spinningmagnets » Mon Sep 11, 2017 2:16 am

Here's an intro to VFD, I believe they are designed to work with induction motors, instead of PMDC

https://www.vfds.com/blog/what-is-a-vfd

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Alan B
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Re: 3 Phase E-bike?

Post by Alan B » Mon Sep 11, 2017 6:55 am

The PhaseRunner is similar to a miniature VFD in terms of hardware, with three phase sinewave outputs, but the firmware is designed for a permanent magnet brushless motor instead of an induction motor. The two orthogonal vector currents that are being controlled are set up differently as there is no magnetization current needed with a BLDC type motor, so only torque current is applied, except when field weakening is desired for additional RPM by reducing back EMF, in which case some negative magnetization current is used. But the vector motor control is quite similar to VFD type controllers, as I understand it. There are folks here on ES who design and program their own controllers.

For small battery powered systems like ebikes, the size, weight, cost, efficiency and high torque at low RPM requirements make BLDC a very attractive choice, and most systems use that. Most ebike BLDC systms use very simple trapezoidal controllers triggered by hall sensors instead of sinewave control for very low cost and simplicity, however lately the sinewave controllers have become less costly and more common.

Welcome to ES.

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marcexec
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Re: 3 Phase E-bike?

Post by marcexec » Mon Sep 11, 2017 10:08 am

I put a small list of (somewhat) typical EV motors on the Wiki:
https://endless-sphere.com/w/index.php/ ... _Selection
That should give you an overview.
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st35326
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Re: 3 Phase E-bike?

Post by st35326 » Wed Oct 25, 2017 12:21 am

dirtybagg wrote:I am new to this forum, and I'm an engineer, so there is likely some over-thinking going on. I'm really enjoying learning about the innovations coming form GRIN Technologies, but I'm wanting a little more clarity on some terminology. In the industrial world, the standard motor controller is a VFD or Variable Frequency Drive. The VFD delivers three phases of PWM DC power to an AC motor, and has common use in household appliances like the clothes washing machine, and it's what drives many modern E-cars. A few advantages of VFD control are:

1: a built-in gearing system (motor speed is tuned by frequency, which minimizes some limitations of gear reductions and motor winding configurations)
2: regenerative braking is included
3: VFD has favorable efficiency for stationary use, even after AC to DC inverter losses, which means even greater efficiency for mobile application as the battery is already supplying DC.

Is VFD-like control available for a Brushless motor? Is anybody making VFD e-bikes? What is implied by controller names like "Phase Runner"? three phases? What can an Engineer tinker with to make this all possible?

I really like this posting, I wonder if the thin metal laminate are much heavier than magnets. Maybe its liquid cooling that so many induction motor setups seem to have for why they are not used in smaller scale transportation (ebikes, scooters, etc)?

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