Search found 13 matches

by rogervize
Dec 12 2016 5:32pm
Forum: E-Bike General Discussion
Topic: Thoughts on throttle taming?..
Replies: 27
Views: 2148

Re: Thoughts on throttle taming?..

Thanks Alan B.. Have you seen these algorithms executed using analog with combinational logic? I am driving the windings at base frequency in the order of the phases. My motor/alternator is 14 pole. Have you any ideas on using a car alternator for this purpose? My plan is to use a friction drive to ...
by rogervize
Dec 12 2016 4:46am
Forum: E-Bike General Discussion
Topic: Thoughts on throttle taming?..
Replies: 27
Views: 2148

Re: Thoughts on throttle taming?..

Yes Alan B.. you are correct.. and the characteristic tapering of winding current aggravates the problem. I was thinking of my battery as a current source which would be true if it is sufficiently high in voltage to overcome the motor internally generated volts. My project uses a car alternator and ...
by rogervize
Dec 10 2016 4:41am
Forum: Motor Technology
Topic: PM Motor theory - formulae etc.
Replies: 71
Views: 42692

Re: PM Motor theory - formulae etc.

Best to drive the winding with a sine rather than rectangular...
Harmonics are bad.. more losses and stress.
Rectangular drive will cause essentially rectangular current especially at low revs
by rogervize
Dec 10 2016 4:31am
Forum: E-Bike General Discussion
Topic: Thoughts on throttle taming?..
Replies: 27
Views: 2148

Re: Thoughts on throttle taming?..

At low road speed the amount of torque required for acceleration is less than the torque required at higher speed for the same acceleration. Reason is .. at higher speed more force/torque is required to overcome wind and rolling resistance... leaving less torque available for acceleration. I am not ...
by rogervize
Dec 09 2016 5:23am
Forum: E-Bike General Discussion
Topic: Thoughts on throttle taming?..
Replies: 27
Views: 2148

Re: Thoughts on throttle taming?..

Trouble is... a small amount of torque at low revs causes much greater acceleration than the same torque at higher speed
by rogervize
Dec 04 2016 5:59am
Forum: Motor Technology
Topic: PM Motor theory - formulae etc.
Replies: 71
Views: 42692

Re: PM Motor theory - formulae etc.

One pitucre explains more than 1000 words :wink: http://www.lorenzoroi.net/prelievi/sviluppiFourier.pdf Are you relying on the winding inductance (including reflected mutual inductance) to resolve into a low harmonic current waveform? At low RPMs that would not be the case and you must surely have ...
by rogervize
Dec 02 2016 5:03am
Forum: Motor Technology
Topic: Adjustable Voltage Controller
Replies: 10
Views: 1188

Re: Adjustable Voltage Controller

Yes .. delta wye change-over would be my guess as well.
It is certainly a simple way to achieve a 'dual' ratio.
Of course the winding might be under more stress if designed for the higher voltage.
by rogervize
Dec 02 2016 4:54am
Forum: Motor Technology
Topic: Question: development of a 3 phase BLDC motor controller.
Replies: 4
Views: 720

Re: Question: development of a 3 phase BLDC motor controller

The power mos-fet driver chips are working hard so best use an individual device for each hi-lo pair of fets. You need to switch the fets off really fast and that is hard with the huge gate capacitance of each fet. The separate high side pwr supply is to drive N-Channel fets on the high side since t...
by rogervize
Dec 02 2016 4:17am
Forum: Motor Technology
Topic: Adding halls to BLDC motors
Replies: 99
Views: 14994

Re: Adding halls to an Astro Flight 3220 inrunner

There are many positions for the sensors that will work.. sort of. Without a dyno and an embedded thermo you will never know the optimum placement. Basically remember the Hall Sensor is the trigger for firing off a pulse to the corresponding phase winding. You need to compensate for the delay or adv...
by rogervize
Dec 02 2016 1:49am
Forum: Motor Technology
Topic: PM Motor theory - formulae etc.
Replies: 71
Views: 42692

Re: PM Motor theory - formulae etc.

Big problem with many controllers is the rectangular drive waveform .. softened only by some winding inductance. Also the PWM technique for controlling input pwr/volts is crude. At low speeds the motor obviously needs lower volts but achieving this by adjusting the Pulse duty cycle is crude. The res...
by rogervize
Dec 02 2016 1:30am
Forum: E-Bike General Discussion
Topic: Thoughts on throttle taming?..
Replies: 27
Views: 2148

Re: Thoughts on throttle taming?..

Anything that uses a time delay is 'sleazy'.. A ramp is good but that's part of what a throttle is anyway. The best way to 'soften' the throttle is to incorporate road speed into the algorithm. Better still some feed-back from an accelerometer... since acceleration is what is ultimately required. So...
by rogervize
Dec 01 2016 11:37pm
Forum: E-Bike General Discussion
Topic: Thoughts on throttle taming?..
Replies: 27
Views: 2148

Re: Thoughts on throttle taming?..

The electric motor has inherently greater torque at low RPMs. This causes the jerkiness you refer to... since only low torque is required from starting off. As speed builds you need more torque to overcome rolling resistance and wind. So the controller needs to factor in the speed or at least incorp...
by rogervize
Dec 01 2016 11:15pm
Forum: E-Bike General Discussion
Topic: Whos riding high ? .... voltage
Replies: 30
Views: 2330

Re: Whos riding high ? .... voltage

High voltage is good.. The technical challenges are in the design of the motor. Higher insulating ability... but thinner wire. The motor needs to be designed specifically to the voltage and RPMs as these are closely related. Probably not many are currently available for smaller EVs .. and the sweet ...