I need a speed controller for my Agni motor

[john]

does anyone know the best speed controller for an Agni 119 motor which is 8.5 kw 48 volt dc , 4000rpm please

[Peter]

Hi John. Look on eBay for Curtis 48v

[Isaac96]

Hi,

How DIY do you want to go?
Either use a Prius inverter with some rewiring, or get something like a Curtis controller.

https://www.cloudelectric.com/product-p/1204-403.htm

-Isaac

[john]

Hi, I have heard you mention this Prius inverter before, and yes these are readily available in the UK for around £50, sounds ideal, but I am not able to use one of these simply because I would not know how to reconfigure it for my needs, is there anyone on here who you know, would be able to help me with this?

How DIY do you want to go?
Either use a Prius inverter with some rewiring, or get something like a Curtis controller.

https://www.cloudelectric.com/product-p/1204-403.htm

-Isaac

[john]

Hi John. Look on eBay for Curtis 48v

Hi, will have a look thanks

[SciroccoEV]

The Agni motor is very low inductance. You get better efficiency with a higher switching frequency, which is why the designer Cedric Lynch liked the Brusa controllers. I've added external inductors to help Curtis controllers out.

The other thing to consider is that the no-load and full load rpm are very close together and they can be quite jumpy when voltage (rpm) controlled. The Brusa controller used current (torque) controlled and was also capable of regen.

The Cycle Analyst can be used to modify the throttle input to some controllers to convert them from voltage to current mode. It's possible to modify Curtis controllers from 0 to 5K throttle input, to a voltage input.

[john]

The Agni motor is very low inductance. You get better efficiency with a higher switching frequency, which is why the designer Cedric Lynch liked the Brusa controllers. I've added external inductors to help Curtis controllers out.

The other thing to consider is that the no-load and full load rpm are very close together and they can be quite jumpy when voltage (rpm) controlled. The Brusa controller used current (torque) controlled and was also capable of regen.

The Cycle Analyst can be used to modify the throttle input to some controllers to convert them from voltage to current mode. It's possible to modify Curtis controllers from 0 to 5K throttle input, to a voltage input.

thanks for your input, you are obviously very experienced in this field, however, I am only interested in acquiring a fairly cheap method of controlling this motor because it is for the purpose of converting my Ford model T to EV, and so speed and efficiency are not top priority, I even want to retain the original gear box which is only 85% efficient, the intention is to carefully remove and retain the engine and all ancillary parts for maybe future use, I just want it to be EV whilst in my ownership, on this subject, and taking into account what you have said, any ideas along the lines of using just a simple variable resistor for this purpose, thanks

[Isaac96]

Hi John,

I hope you don't mean using a variable resistor to control the motor without any controller.
The problem with the use of a resistor is that it has to dissipate all the power that is not used by the motor. So you'd need a resistor with a similar power rating to the motor.

http://www.agnimotors.com/ talks about their '20kw pure torque motor controller' which would be very well matched for the Agni 119 motor.

@sciroccoEV - Curtis controllers run at 15.6Khz - do the Brusa's run at 32? I couldn't find any information on the Brusa ones.

-Isaac

[SciroccoEV]

AGNI are part of Saietta these days. Whilst they have a stock of motors and controllers, they're not making them any more and have not been able to offer servicing, or supply things like replacement brushes for some time.

The motor controller is a pain. I'm informed they spent £700,000 of grant money and a matching amount of venture capital on its development. At the end of this, they have no in house knowledge of the code and cannot make changes or fix bugs. It's clear that it was intended to have CAN comms capability, but the only thing the CAN is used for is setting the parameters and it requires the use of a specific and quite expensive USB to CAN adapter. You have to avoid running high current cables over certain areas of the controller casing, or you'll interfere with the internal current sensors.

My memory was failing me on the controller Cedric used to like, It wasn't one of Josef's products, but one from ASMO (the electric race cart manufacturers), who owned Lemco at one point. It was the MD-204 and ran at something like 25kHz. I've got one hanging around somewhere, but it needs to be repaired.

A Curtis controller is probably the easiest solution.

[john]

AGNI are part of Saietta these days. Whilst they have a stock of motors and controllers, they're not making them any more and have not been able to offer servicing, or supply things like replacement brushes for some time.

The motor controller is a pain. I'm informed they spent £700,000 of grant money and a matching amount of venture capital on its development. At the end of this, they have no in house knowledge of the code and cannot make changes or fix bugs. It's clear that it was intended to have CAN comms capability, but the only thing the CAN is used for is setting the parameters and it requires the use of a specific and quite expensive USB to CAN adapter. You have to avoid running high current cables over certain areas of the controller casing, or you'll interfere with the internal current sensors.

My memory was failing me on the controller Cedric used to like, It wasn't one of Josef's products, but one from ASMO (the electric race cart manufacturers), who owned Lemco at one point. It was the MD-204 and ran at something like 25kHz. I've got one hanging around somewhere, but it needs to be repaired.

A Curtis controller is probably the easiest solution.

hi again and thanks, it sounds like I have bought myself a problem,

[SciroccoEV]

Brushes last pretty well and are available from third party sources. The motors aren't technically difficult to service, you just need to build a special rig to pull the motor apart. The only thing holding the casing together is the magnets.

[john]

Brushes last pretty well and are available from third party sources. The motors aren't technically difficult to service, you just need to build a special rig to pull the motor apart. The only thing holding the casing together is the magnets.

thanks for that reassurance and so it is back to trying to find a cheap speed controller, I will carry on with my search

[john]

The Agni motor is very low inductance. You get better efficiency with a higher switching frequency, which is why the designer Cedric Lynch liked the Brusa controllers. I've added external inductors to help Curtis controllers out.

The other thing to consider is that the no-load and full load rpm are very close together and they can be quite jumpy when voltage (rpm) controlled. The Brusa controller used current (torque) controlled and was also capable of regen.

The Cycle Analyst can be used to modify the throttle input to some controllers to convert them from voltage to current mode. It's possible to modify Curtis controllers from 0 to 5K throttle input, to a voltage input.

quote, 'I've added external inductors to help Curtis controllers out.' I have now purchased a Curtis controller, Could you please tell me what external inductors you added, thanks

[SciroccoEV]

I've used salvaged welding reactors in the past, but a Prius boost inductor would probably be a good choice these days.

[john]

I've used salvaged welding reactors in the past, but a Prius boost inductor would probably be a good choice these days.

thanks, but I have no idea what these are or how they are integrated with the speed controller, can you explain, or better still, for simplicity, will this controller work to a fashion without this mod

[SciroccoEV]

It will work without, but driveability and in particular low speed control, would be better with the inductor.

The inductor is just wired in series with the motor.

[john]

Hi John. Look on eBay for Curtis 48v

Hi Peter, I have bought one of these thanks to your suggestion, have you actually used one of these in a conversion, if so how were the results thanks

[Peter]

Hi John. Glad to help and hope your project goes well. I have a 72v version of the Curtis running a HUGE 400A series wound motor. Sadly what its in is ready for the scrap heap now unless it finds a new home. Good luck. Peter