Electric Unicycle motor with burning MOSFETs

Thread Starter

Paul V12owner

Joined Jan 8, 2022
3
Hi, everybody. I have an electric unicycle (EUC) that has numerous issues reported by other owners on dedicated forums and on social media. The main issue with this unicycle is that it cuts out while riding it, which can led to severe accidents or even death (it has an max speed of 40mph). These machines are great fun, very practical and extraordinary compact, which made them very popular with niche riders. Unfortunately, from the beginning this form of transportation was plagued with problems: motor cut outs, instantaneous combustion of the batteries, poor water proofing, weak cases and other design, manufacturing and quality issues. Almost all are fabricated in China at this moment, with another producer in Korea, if I remember well.
To make a long story short, one of the producers that was known to make a little bit more safe and more reliable EUCs, InMotion, has started the production of a model(V12) that from the specs that were provided by the manufacturer promised to be of much better quality and with enticing speed and manoeuvrability. At this moment many received their V12s and alarmingly a lot of cut outs and accidents, resulting in bad injuries, started being reported. The reason for these failures are the burning MOSFETs: 12x Infineon IPP023N10N5 . The EUC has a 100.8V battery. The manufacturer, InMotion, claims that they received boards with bad quality MOSFETs from their controller board supplier. From what we read on this forum and other similar sites, many of the owners of this EUC, including myself, believe the MOSFETs were of underrated power for the voltage available on this unicycle. We had to become investigators of these problems ourselves, since we have little trust in what the manufacturer tells us. Would you please help me in clarifying this issue?

An amendment here with some more info: the battery is of 1750WH capacity and the motor is 2500W nominal, 5000W peak power. It might be useful.

In the case the MOSFET are not chosen properly I intend to change them with a higher V one like the Infineon IPP041N12N3 G which has close fall and rise times.
 

Alec_t

Joined Sep 17, 2013
12,732
I have no experience with electric unicycles, but it seems to me that if a rider is simply trying to balance on one, or move slowly, rather than go forward at speed, the motor is essentially stalled and could be drawing a much larger than average current. That would stress the MOSFETs. So it may be excessive current (hence heating), rather thn excessive voltage, which is a primary cause of failure?
Each to his own, but because of the problems you mention above you wouldn't catch me on an electric unicycle.:eek:.
 

Thread Starter

Paul V12owner

Joined Jan 8, 2022
3
I have no experience with electric unicycles, but it seems to me that if a rider is simply trying to balance on one, or move slowly, rather than go forward at speed, the motor is essentially stalled and could be drawing a much larger than average current. That would stress the MOSFETs. So it may be excessive current (hence heating), rather thn excessive voltage, which is a primary cause of failure?
Each to his own, but because of the problems you mention above you wouldn't catch me on an electric unicycle.:eek:.
We use it for riding. You can balance on one for a while with no problem. The MOSFETs are usually burning when stressed as when hitting a bump in the road when the motor has to suddenly output more torque.
 

Alec_t

Joined Sep 17, 2013
12,732
Ah. Thanks, Bertus. I wouldn't want to encourage any activity contrary to the site's Rules.
 
Last edited:

Thread Starter

Paul V12owner

Joined Jan 8, 2022
3
We ride it usually, but the one can also balance on it as you describe with no problem. The issue here is that they choose in our opinion the wrong MOSFETs.
 

Lumenosity

Joined Mar 1, 2017
614
We ride it usually, but the one can also balance on it as you describe with no problem. The issue here is that they choose in our opinion the wrong MOSFETs.
Might be the correct Mosfets for the application but could also be the Mosfets are in Parallel and are running out of sync and overheating due to a current imbalance.
 
Hi, everybody. I have an electric unicycle (EUC) that has numerous issues reported by other owners on dedicated forums and on social media. The main issue with this unicycle is that it cuts out while riding it, which can led to severe accidents or even death (it has an max speed of 40mph). These machines are great fun, very practical and extraordinary compact, which made them very popular with niche riders. Unfortunately, from the beginning this form of transportation was plagued with problems: motor cut outs, instantaneous combustion of the batteries, poor water proofing, weak cases and other design, manufacturing and quality issues. Almost all are fabricated in China at this moment, with another producer in Korea, if I remember well.
To make a long story short, one of the producers that was known to make a little bit more safe and more reliable EUCs, InMotion, has started the production of a model(V12) that from the specs that were provided by the manufacturer promised to be of much better quality and with enticing speed and manoeuvrability. At this moment many received their V12s and alarmingly a lot of cut outs and accidents, resulting in bad injuries, started being reported. The reason for these failures are the burning MOSFETs: 12x Infineon IPP023N10N5 . The EUC has a 100.8V battery. The manufacturer, InMotion, claims that they received boards with bad quality MOSFETs from their controller board supplier. From what we read on this forum and other similar sites, many of the owners of this EUC, including myself, believe the MOSFETs were of underrated power for the voltage available on this unicycle. We had to become investigators of these problems ourselves, since we have little trust in what the manufacturer tells us. Would you please help me in clarifying this issue?

An amendment here with some more info: the battery is of 1750WH capacity and the motor is 2500W nominal, 5000W peak power. It might be useful.

In the case the MOSFET are not chosen properly I intend to change them with a higher V one like the Infineon IPP041N12N3 G which has close fall and rise times.
It was shocking to see they used a 100V MOSFET in a design with 100v battery. I've designed high speed pulsers using MOSFETs and would never run them at max Vds voltage. I like the 120v replacement with same current rating that you picked ... Needs more detailed analysis of circuit ... why are they designing with through hole parts?

Good luck,
Valerie
 
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