KT Square wave vs sign wave

[rocketman58]

Some time back I bought a 500w Bafang geared hub drive kit off Amazon. Not liking the way the controller worked, I replaced the standard Bafang controller with a KT square wave controller (48ZWSRM). It works very well, except it is a little noisier than I would like. I plan to use the same setup on another bike, but I was thinking of using a KT sine wave controller (48SVPRM) as it is supposed to be quieter and smoother. Is this controller compatible with the Bafang 500w geared hub drive? Basically I want to know if the 48ZWSRM and 48SVPRM controllers are interchangeable. Thanks!

 

[docw009]

I've replaced KT square wave with KT sinewave. Can't really say if it's quieter or smoother. I have a Bafang BPM front motor being spun by a sine wave. It's loud and sets up a resonance with the fork that makes an irritating squonking noise.. I had to pull off the fender to lessen the noise.

Some KT square wave controllers are sensorless. I have one but it spins a sensored motor, making the motor's Hall sensors redundant. If the motor were sensorless, it couldn't run on a sinewave, as I believe all those are sensored. Sensorless controllers only have the three thick phase wires, and sometimes three wires for a speed sendor going to the motor. You can't tell wiyj a visual inspect, if they use the 9 pin molded connectors.

That would be the only show stopper, if your original Bafang and the KT square wave, plus the motor were all sensorless.

 

[motomech]

Some time back I bought a 500w Bafang geared hub drive kit off Amazon. Not liking the way the controller worked, I replaced the standard Bafang controller with a KT square wave controller (48ZWSRM). It works very well, except it is a little noisier than I would like. I plan to use the same setup on another bike, but I was thinking of using a KT sine wave controller (48SVPRM) as it is supposed to be quieter and smoother. Is this controller compatible with the Bafang 500w geared hub drive? Basically I want to know if the 48ZWSRM and 48SVPRM controllers are interchangeable. Thanks!

Are we talking BPM? 22 A max seems a little low. It would be nice if you could find a 9 FET controller (not too big) in the 25 to 35A range. Don't worry about the differences between a "sine-wave vs.s square-wave, They're really not much difference in practice. A same-rated Square wave will maybe hit a little harded intionally, and be a little noisier, but not much. The are some "hot-rod controllers like from Lynn that act and feel a lot different.
Focus instead on Amp ratings, size and type/size/etc. of the display.
If you get at or over 30 Amps max, you might want to think about the size/quality of the phase/power wires and their connectors

 

[rocketman58]

It sounds like "upgrading" to a sine wave controller would not be worth the cost. Especially since there would not be much if any difference, the sine-wave may not work with my motor, and the square wave one I have works very well.

 

[E-HP]

It sounds like "upgrading" to a sine wave controller would not be worth the cost. Especially since there would not be much if any difference, the sine-wave may not work with my motor, and the square wave one I have works very well.

Wouldn't help with gear noise, only motor noise, so you're probably right. Out of 3 sine wave controllers I've used, I noticed the KT is the quietest though.

 

[amberwolf]

Most likely you won't notice enough difference in noise, if that's your reason, to make it worth messing with if the system works as it is.

The gear noise is probably greater than the trap/square noise. (at high motor speeds, like in small wheels at >15-20mph, it can be VERY loud in some motors like the GMAC).

If you're building a complete second bike (leaving the original intact) then as long as the controller is capable of either sine or square/trapezoidal, and sensored/sensorless (dual mode), it shouldn't hurt to try a new one. But if you like the way the present system works and just want to easily duplicate that, stick with what works.



Note that FOC controllers (like the Grin Phaserunner, etc) can run completely sensorless and still be sinewave--it's usually just the "lookup table" sinewave (that just feed a sinewave instead of square wave, but still just force it in there) that are sensored-only for the sinewave version or mode (like the old Grinfineon I also have).

But an FOC controller is more complex, has more things the user must setup specifically for their motor and system to get it to work at all, much less well, and is generally too much of a PITA unless you have a good reason for going that way, or you just like tinkering.

 

[nicobie]

The are some "hot-rod controllers like from Lynn that act and feel a lot different.

Is Ed Lynn still selling his most excellent controllers? I have a 12 fet one that I've shunt modded and push 35A 96V through without a problem. I use a temp sensor in the motor and watch it.

 

[motomech]

Is Ed Lynn still selling his most excellent controllers? I have a 12 fet one that I've shunt modded and push 35A 96V through without a problem. I use a temp sensor in the motor and watch it.

Well, I just ran a search for his products page,...nothing.
Years ago, he built me a sm. 6 FET Mini-Monster, 25 Amps max in a box not much bigger than a pack of cig.s w/ a custom LVC. The thing was a hoot, on a frt. mounted mini-motor, it would spin the tire on dry pavement.
Also had a 6 FET Grinfineon, about the same thing.
So, I looked at the Grin site and they still list them w/ info on their products page, but don't sell them anymore. End of an era, I guess.
Pretty hard to compete w/ $30 to $50 genarics, even though they, from a performance perspective, are weak.
And I guess most DIY'ers want some sort of diplay.

 

[amberwolf]

Well, I just ran a search for his products page,...nothing.

The page is still there

LYEN Controllers

dunno if he's still running it.