BLDC for exercise bike

[cupoftea]

Hi,
For an exercise bike, what sort of motor, or should i say, generator would you use?
You need to make it hard to cycle , like "uphill", and easier, in gradations.
So are we talking BLDC, and making it drive the pedals one way, whilst the biker pedals against that?

Presumbaly you use the principle of making the user try to bring the south pole to the south pole....so advance the stator south pole just ahead of the rotor south pole......and advance it less when you want harder cycling?...so that the user will feel more of the replusion force of the like pole?

Eg for an exercise bike, you can easily sense the position of the pedals...which are connected to the rotor...so you know exactly how far ahead of the rotor you want the stator field to be.....and you ensure that you offer south pole to south pole...so that it gives the repulsion force for the "rider" to ride against?...the more current in the coil, the harder the repulsion.

Presubaly no FOC etc is needed. Just up and down current, and commutate from coil to coil in phase with, and slightly ahead of, the "rider"?

And presumably there is the other way of just having a BLDC in regen mode and using it to say charge a battery?

 

[dick_freebird]

BLDC, or a now commonly available automotive
PM brushless alternator, or for that matter since it's
just supposed to be a "human load", a regular old
wound-field alternator.

Hang a wide range DC-DC off the output with a
beefy burden resistor, dialing up the output voltage
dials up current dials up shaft torque. A hysteretic
converter might be a handful of parts and give you
a wide input range?

Of course you could go all steampunk and just
have a cool panel of big-ass finned power resistors
and knife switches....

 

[betwixt]

Just control the load on the generator. A complete short would make it very hard to turn, a complete open would let it turn freely so by adding a controlled load you can set how hard it is to pedal.

Brian.