Electrical Engineering - 60 vdc scooter hub motor borken

Author

60 vdc scooter hub motor borken

tracy

2007-10-02, 3:25 am

I have two of these scooters, I am on the east coast, a friend on the
west coast sent me his motor and controller to try and figure out what
is wrong with it, I have made headway, got it working, kind of.

First, this is a two speed motor, it has three power wires going to it
along with 5 small tiny wires that are probably the HALL sensors.

Two chang speeds, they have a hollow axle with a splined shaft in it,
an external selenoid plunger moves this shaft back and forth.

Inside the motor that shaft is moving a plate that has three contacts
on it, they are the three power wires from the controller.

On the outside of the rotating plate, is a hub that the plate sits
in,
it has six contacts, so when the plate is turned one way, it is
connecting to three contacts, when the plate is moved the other way,
it is connected to three other contacts.

When the bike is in low speed hi torque, the plate is connecting the
power wires indivually to three separate wires that appear to go into
the windings separately.

When the plate is turned the other way for high speed, all three power
wires become common to each other, and also become common to all three
winding wires too.

Now, here is the problem, when he first sent me the motor controller
he didnt know if the motor controller or both were bad.

The shift selenoid had not worked for awhile, and he is not that
technical, I figured out from talking to him that he had been riding
the bike in high speed low torque for some time, that of course is
going to make the motor a little hotter because you arent supposed to
be in high until you hit 15 mph.

Eventually, the motor quit, I did some diagnoses over the phone and
found that if he put the bike on the stand and manually moved the
spline shift shaft to low, that if he spun the tire by hand it would
start going, same for high but he said it had a load grinding sound.

So he sent me everything, I quickly found the controller was ok and
then opened the motor, first I found that one of the maim power wires
had come unsoldered from the rotating shift plate and another fell off
while looking at it.

So I soldered these back on an testing again.

Now the bike would start in low and high on its own and low sounded
good and like it should, but high growled real bad, and I had noticed
that when the plate moved back and forth one of the power wires was a
tad long and might be rubbing, so I opened it up, shortened it and
soldered it back.

Now for the problem, prior to putting the motor back on and testing
again I decided to check something else, I took a known good motor and
put it in low and turned it by hand, then high and turned it. A slight
resistance but basically no difference between low and high when
turning the motor manually.

Then I tried his, in low, turns fine, when I put it in high, very
hard
to turn, it goes and stops, goes and stops, I counted the pausing and
it was 19 the same as the number of permanent magnets in the motor.

So it appears that when the shifter is placed in high, and all the
power wires and windings become common with each other, the motor does
not turn freely and the permanent magnets are I guess feeding from one
winding to another or something and causing this hesistation to turn
and the growling sound when you try to run it in high.

When I was test turning the know good and the bad motor, both are
disconnected completely and on the bench, so I am baffled, has he
fried the windings or something?

Palindrome

2007-10-02, 9:25 am

tracy wrote:
> I have two of these scooters, I am on the east coast, a friend on the
> west coast sent me his motor and controller to try and figure out what
> is wrong with it, I have made headway, got it working, kind of.
>
> First, this is a two speed motor, it has three power wires going to it
> along with 5 small tiny wires that are probably the HALL sensors.
><snip detail >
> so I am baffled, has he
> fried the windings or something?
>

I would be looking for a short internally between two of the windings.
This, in high speed mode when the windings are commoned, creates "a
shorted turn" and that acts as a brake. In low speed mode, the
electronics in the controller prevents the shorted turn from forming.

This is fairly easily proven - if you disconnect two of the three motor
wires, put it in low speed and turn by hand, the faulty motor should
feel much the same as the good one.

Ordinarily, simply putting a suitable rectifier diode in series with
each of the motor windings would be a work around - as that too would
prevent a shorted turn forming. However, that would almost certainly
remove the electronic braking and energy recovery (hopefully) built-in
to the controller and could cause the loss of "reverse gear".

It might be possible to put these diodes in, but add reverse parallel
semiconductor switches that can bypass the diodes when braking or
engaging reverse.

--
Sue

tracy

2007-10-02, 1:25 pm

Sue, read this after I fixed it but basically, you nailed it.

There was a big glob of solder that was nano inches away from another
contact.

So three low windings, three high windings

In the right position the gear shifter was stressing plastic enough
that the globs touch and one phase of the low and hi were energized
together, wicked some solder off and it is working great.

THANKS FOR RESPONDING, posted a couple of places and this was the only
help, and it was right!!!

On Oct 2, 4:53 am, Palindrome <m...@privacy.net> wrote:
> tracy wrote:
>
>
> I would be looking for a short internally between two of the windings.
> This, in high speed mode when the windings are commoned, creates "a
> shorted turn" and that acts as a brake. In low speed mode, the
> electronics in the controller prevents the shorted turn from forming.
>
> This is fairly easily proven - if you disconnect two of the three motor
> wires, put it in low speed and turn by hand, the faulty motor should
> feel much the same as the good one.
>
> Ordinarily, simply putting a suitable rectifier diode in series with
> each of the motor windings would be a work around - as that too would
> prevent a shorted turn forming. However, that would almost certainly
> remove the electronic braking and energy recovery (hopefully) built-in
> to the controller and could cause the loss of "reverse gear".
>
> It might be possible to put these diodes in, but add reverse parallel
> semiconductor switches that can bypass the diodes when braking or
> engaging reverse.
>
> --
> Sue

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