Railbike Motors

[Rail Rider]

I am new to this forum and would like to get some expert opinions on how to slow down the loaded RPM of the Golden Motor 3KW motor operating on 48 volts while using the VEC-200 controller.  We're currently retrofitting 11 pedal powered railbikes with electric motor assist.  We have selected the air cooled HPM3000 motor because of it's quality design and power/torque capabilities.  After doing further testing, we find the loaded vehicle motor RPM to be too fast for safe travel on the railroad tracks.  We have changed the gear ratio to the smallest motor sprocket and largest axle sprocket that will fit the railbike.  We have also communicated with Johnson Liu at Golden Motor in China for possible options.  He is proposing to custom build the 3KW motor to operate at 1000 RPM with a detuned power output of 1300 to 1500 watts.

Before we go down this expensive path, can any of you suggest operating voltage or programming changes that would allow the 3KW motor to run slower (1000 RPM) while not overheating?  The programming software for the VEC-200 controller does not appear to allow reducing the operating voltage below 48 volts.  Any help or suggestions would be very much appreciated.   

[Bikemad]

Hi andto the forum.

I think the problem is mainly due to the VEC200 controller using torque control instead of speed control, but I don't think this can be changed.

The motors need a certain amount of load on them for the controller to be able to regulate the rpm. With insufficient load on the motors, they will simply speed up to high rpm even with just a small amount of throttle. 

Reducing the gearing sufficiently would definitely reduce the top speed, but I don't think the throttle will be very proportional using torque control with even less torque being applied to the motor. 

If you only require 1500 Watts, I'm wondering whether the 2000 Watt BAC-0501 controller might provide a solution to your problem:



I don't know if this controller is compatible with the 3kW motors, or even if it uses speed control or torque control, but it might be worth asking Johnson Liu if it would work.

Alan
 

[Rail Rider]

Thank you Alan for your reply and allowing us to be part of this forum.  We have requested to have Johnson Liu build us a sample 3KW Golden Motor to operate at 1000 rpm.  I also queried Johnson about the use of the BAC-0501 controller to allow "speed control" when operating this new 3KW detuned motor.  His reply stated the BAC-0501 controller is designed for a maximum of 1500 watts and cannot supply enough current for this new motor.

Because of this, I am now looking at the KBL model Kelly Controllers which provide variable operating voltage ranges, as well as speed control and variable regenerative braking.  Does anyone have any experience using the Kelly Controllers with motors from Golden Motor?

[Bikemad]

I don't understand why the controller is advertised as being 2000 Watts if it's only designed for a maximum of 1500 Watts.

I would have thought that it would have sufficient output for your intended use, especially when "he is proposing to custom build the 3KW motor to operate at 1000 RPM with a detuned power output of 1300 to 1500 watts".

How many riders (or sets of pedals) does each rail bike currently have? Bearing in mind that the average non-cyclist would be lucky to produce as much as 200 Watts continuously.
If they only have four riders, that's just 800 Watts of total pedal power, so 1000-1200 Watts of motor power with suitable gearing should be plenty, especially if the railway track is reasonably level.

Unfortunately, I don't have any experience of using Kelly controllers with GM Motors. 

Alan
 

[Rail Rider]

I suspect I want my cake and eat it too!  I would like the regenerative braking feature to be always on and not triggered by either releasing the throttle or pulling the brake lever.  This would function as a safety feature to keep the railbikes from accelerating down a hill and out of control if the operator is not paying attention!  I plan on using a SPST toggle switch to ground the normal brake wire to accomplish this.  However in the normal scenario, this action disables the throttle by cutting power to the motor.  Is there any way to override this function through wiring and/or programming?  The controller being used is a VEC-200.  Any thoughts or suggestions would be appreciated?  Wishing everyone Happy Holidays!

[Bikemad]

It would not make sense to have have regenerative braking drawing power from the motor and the throttle trying to send power to the motor at the same time.

It might be possible to override the brake switch function using a suitable electronic circuit to operate a relay which would open the closed brake circuit when the throttle was activated, but this would be very dangerous if the throttle stuck, as applying the brakes with the throttle applied would no longer cut the power to the motor. 

I'm not sure how effective the Auto EBS is at slow speeds, but it might be worth enabling the EBS Auto-Mode and setting the EBS Auto_Mode Speed (rpm) as low as possible, as this should then cause the EBS to operate as soon as the throttle is released regardless of the actual speed.

It should be possible to have some form of external electrical circuit/switch using an Arduino to monitor the motor rpm from the Hall sensor pulses that would automatically apply the Regen when the motor speed exceeded a predetermined rpm setting to safely limit the top speed of the vehicle.  You'll need to do some Googling to see if anything already exists that would be able to perform this function.

Alan