Most likely that hub motor is already wound for torque or WYE. Do you know what the KV is? That speaks volumes about how it's wound. You can have one motor and wind it on the fly for torque or speed. WYE is good for torque, but not top speed. Delta draws more current than WYE, but the exact same motor wired for Delta will be 1.73 times faster than it will be in WYE. So if you get 30mph in WYE, multiply that by 1.73 and you have some idea what you will get with it set up in delta (52mph). I like your your little moped. I wish I had a tiny one like it. I would load a regular wheel on the back, add an outrunner (80-100) and that little toy would do 55mph.
I suggest that you stay at 48 volts and then build a lot of capacity.
There's 3 ways to get more speed out of a setup. With brushless motors you are limited by its maximum RPMs. It really defines how fast you can go so you have to work around it some how. These 3 ways are pretty much how you do that.
1. Have lots of available current and a strong motor controller that can deliver it to the motor. There is limits to this approach. There's only so much torque any given motor can produce and throwing more current at it wont make it pull any harder and it just gets hot and burns up. With an inrunner or outrunner, you can leverage that extra torque and user a closer to 1:1 gearing ratio to convert more motor turns into wheel turns. With a hub motor, all you get is more torque since there's no way to gear it differently. As a result, I tend to use inrunners and outrunners and ignore hub motors.
2. More voltage. KV X supply voltage = max motor RPMs. So a 50 kv motor at 48 volts will produce 2400 RPM. A 50kv motor at 72 volts produces 3600 RPMs. More motor RPMs means more wheel speed. For a hub motor, this is a great way to get more speed out of it. It is a very common way people increase their top speed. I went from 48 volts to 72 volts myself for this reason. There is one significant drawback. 48 volts is 12 LIPO or LION cells in series. 72 volts is 20 cells in series. OK great so now I have the higher voltage, but at significant increase in cost for more cells. Also, 12 8000mah cells in series have a total capacity of 8000mah. 20 8000mah cells in series still have a total capacity of 8000mah. That basically means pull 8 amps at 48 volts or at 72 volts and you will still get 1 hour of power. If you are looking for the best bang for your buck build for lots of capacity, but less voltage. That means lots of cells in parallel at 12 cells rather than fewer cells in parallel because they got used up getting you to 20 cells in series. If you can afford it or have a way to pull off cheap cells, well I suggest doing both...higher voltage and lots of capacity. This is my battery thread: https://endless-sphere.com/forums/viewtopic.php?f=14&t=76013 I use laptop batteries which I can get used ones for free.
3. Rewire your motor so it can be switched from WYE to delta. It means 7 wires coming out of the motor rather than 4 (Normally you have 3 phase wires and a hall cable), but it means with a beefy 3 pole relay, that you can switch from WYE to delta on the fly. Think of it as a 2 speed transmission, that has no mechanical losses. First gear (WYE), gets you from a stop to 30mph, then you flip a switch, go into second gear (delta) and cruise on up to 50mph. Here's a great thread on WYE/delta switching: https://endless-sphere.com/forums/viewtopic.php?f=2&t=9215&hilit=doctorbass+wye+delta+switching
You will need to fish the temperature sensor inside the axle so you can get it inside the motor and next to the windings. That means taking apart the motor. With a hub motor since it has covers that separate you from the actual motor, it's hard to get a reliable temperature reading from the outside of the motor...and it's spinning. You need the tempurature sensor on the motor windings for it to be effective. A hub motor is effectively an outrunner with super low Kv, but typical outrunners have easy access to the motor windings. With an inrunner, the motor windings are inside the motor can and the magnets spin in the middle of the windings. A lot of times, you can carefully drill a hole through the motor can and right into the iron in a motor winding to get tempurture from the outside. I have open end plates on my inrunner motors so I run the sensor in through the end plate and then cram it down into the windings someplace.
Torque vs speed. Look at the size of that motor compared to what you already have on your scooter. It's going to develop lots more torque that your current motor no matter how it's wound. I wouldn't bother with a torque winding personally.
Sine vs trapazoidal controllers...they are a little quieter, but I can't tell which controller I am using. Torque feels about the same. And you already know how loud your existing motor is...it's already not loud and you probably have a trapazoidal controller. I wouldn't worry about this very much. It's a minor detail compared to other things. If I had $300 to spend on a controller and one was a 300 amp trapazoidal and the other was a 200 amp sine..well I would probably buy the trapazoidal. You pay more for a sine wave controller. At the end of the say, I'm willing to sacrifice a little noise for more overall capacity.
