Currie-EZip ebike Kit $289.88 - Amazon.com

[neptronix]

In a stall situation or coming off the line the 9x7 motor will draw up to 130A max at 36v at that point the windings can no longer accept any amps because its being limited by the resistance of the windings.

Which would make them red hot! They add a fuse to prevent motor burn up.

Do you mean to say that there are fuses in 3 phase hub motors?
I haven't found any in any of the motors i've pulled apart, where are those fuses DrkAngel?

[icecube57]

48v graphs

[icecube57]

5303 Motor at 48v 30A and 100A Controller

[DrkAngel]

In a stall situation or coming off the line the 9x7 motor will draw up to 130A max at 36v at that point the windings can no longer accept any amps because its being limited by the resistance of the windings.

Which would make them red hot! They add a fuse to prevent motor burn up?

Do you mean to say that there are fuses in 3 phase hub motors?
I haven't found any in any of the motors i've pulled apart, where are those fuses DrkAngel?

Search the windings! Most all, should have thermal fuses, look for the odd piece, or pieces, of small tape.
Or, look for the multiple ones in the controller, or, the one in the battery pack.
Internal circuit might have surface mount, resister looking, diodes, with no markings = probable fuse function.
Often there are thermal fuses - self resetting breakers, in-line usually shielded inside a protective tube.

[icecube57]

Ive opened and serviced most common hub motors and several well known controllers from Keywin Lyen Off brands from ebay... ebikekit.. and golden motor... Ive had kit that came with a glass inline fuse... thats about it sir. Out of the many forum pictures ... Do you think you can point out one of these "fuses".

[neptronix]

Search the windings! Most all, have thermal fuses, look for the odd piece, or pieces, of small tape.
Or, look for the multiple ones in the controller, or, the one in the battery pack.

On this forum, you can find reports of BMC, MAC, 9C, MXUS DD/geared, Crystalyte etc. hub motors being fried due the enamel being vaporized off.

I have yet to see a fuse inside a controller designed for a hub motor. If you hunt around enough for pics, you won't see any either.

Please spend more time reading the forums.

[amberwolf]

Search the windings! Most all, have thermal fuses, look for the odd piece, or pieces, of small tape.
Or, look for the multiple ones in the controller, or, the one in the battery pack.

While it would be a good idea to have fuses in many pieces of electronics, lots of them don't actually use any, or at least not where you might expect them. Often this is because a failure that would blow it would happen so fast that the fuse could not blow before the failure was catastrophic anyway. Another reason is it's cheaper not to put them in, by a little bit, and most of these things are made as cheaply as they can possibly get by with, safe or not.

Another really big problem with fuses is that if you use one rated for the max current you would want to preserve electronics at, it won't blow fast enough; if you use one rated to blow fast enough it will also probably blow just during surge currents of commutation, especially at motor startup under load.


None of the controllers that i've got, analog or digital, brushed or brushless, have fuses as such. They limit current by reducing the output pulse widths, or entirely cutting of output voltage when necessary, and if something so rapidly exceeds current capacity of the controller various components can blow up or vaporize, cutting off power, but they are not actually intended to be fuses, though the argument could be made that they might as well be.

In my NiMH battery packs, there are blade fuses, to prevent overcurrent draw on the pack. In the Vpower LiFePO4 pack, no; it has a BMS to limit current and for HVC and LVC, by turning off all the output MOSFETs, but it isn't really a fuse. Again, the semiconductors could blow or the shunts vaporize, but they aren't meant to be fuses, if everything is doing it's job.

None of the battery packs I have for tools, laptops, phones, or anything else have fuses, either. The charging inputs on quite a few devices I have do have fuses, but nothing on the path from battery to device usage point(s). Most of the laptops I've worked on over the years only have fuses on the exterior power input, but once it gets past that point, there are usually not any fuses; the BMS in the battery is usually expected to limit any output, and in a catastrophic situation, the FETs tend to blow, shorted, then often vaporize internally, usually cutting power at that point (and probably faster than a fuse would have anyway).

In desktop computers, the same tends to be true--very rarely have I seen even high-end PSUs or server systems with fuses of any kind (even resettable ones) on the internal power flow path--just on the external power inputs, and sometimes on input devices like USB ports or PS/2 keyboard and mouse ports (because if the wires inside a mouse cable become shorted after fraying from movement, you could have quite the interesting object d' art without any other limits on the resulting current flow ).


While most of the cieling fan, box fan and desk fan motors I've opened up have thermal fuses (or in some cases self-resetting thermal breakers), the small or large power tool motors haven't had them (in the windings; a few have had external current-activated breakers). Sometimes on big ones meant to run nearly continously under heavy loads there are thermal breakers, especially on stuff like condenser motors in refrigeration systems of various types.

I'd expected to find them in the induction motors in the washing machines and dryers I have used for parts, but only one had a thermal breaker in it, the rest don't have anything at all, other than (sometimes) a resettable current-type breaker on the power inputs to the control and user-interface section (but not to the motor power).

But none of the vehicle motors, brushed or brushless, have had them as part of the motors. Would've been nice if they did, since it might've preserved a couple of the ones I've got. Even the larger of the two treadmill motors I've got doesn't, though the smaller one has a thermal breaker that could optionally be put in series with it's power connection (but isn't wired into it permanently, so it can be used without that; I don't know if it was used in it's original product).


So...there *can* be fuses or breakers in batteries, control systems, and motors, but there isn't always.

Most of the places I have seen them used tend to be where outside (wall-AC) high-voltage could, in a series of catastrophic failures, result in contact of that voltage with the user of the product, and where that isn't possible, they tend to be absent. I'm sure that's not a comprehensive rule of thumb, but so far is my experience.

[DrkAngel]

?
Have I got this right?
Simplest - most basic, explanation of how a brushless motor works, is that it runs at full voltage, constantly.
Torque is regulated via modulating the amperage applied to the motor, by the controller.
Speed is not affected, except as moderated by "load".
Application of more amps does not affect, top, unloaded, speed, but is used solely to regulate torque.

Amperage application is unlimited, dependent on controller capacity -
or as a function of thermal decay.
(Thermal resistance of wire increases, as its temperature rises.
The application of more amps, shifts efficiency lower, as heat, to torque, production, ratio, increases.)

Question:
Typical 3 phase BLDC - In the sine waveform charts, amperage application seems, full wave-moderated amps.
Duration regulated, multiple full amp pulses, within each "wave" seems to be a viable method, is that an alternate style of BLDC controller?
?

Thanks, icecube57, for the graphs!

[Floont]

...Torque is regulated via modulating the amperage applied to the motor, by the controller.
Speed is not effected, except as moderated by "load".
Application of more amps does not affect top speed, but is used solely to regulate torque

Your second sentence above contradicts your third sentence above. At full-speed, no-load conditions, it is true that current does not affect (not effect) top speed. However in the real world, as road speed increases, air drag (load) increases with the cube of the vehicle air velocity (ignoring aerodynamics). Your top speed is reached when your torque is in equilibrium with drag (plus minor mechanical losses). So if current, which creates your torque, is limited by your controller, your top speed is artificially reduced.

I have personally experienced this effect on my ebike build when I upgraded my controller so it was no longer the limiting factor on amperage to the motor. The motor now takes as much as my out-dated SLA batteries are able to supply. I gained 3MPH on my top speed when I upgraded just the controller without making any voltage changes.

All that said, certainly increasing voltage has the greatest contribution in affecting top speed. But depending on where your current is being limited, it can also affect your top speed too.

FA

[DrkAngel]

...Torque is regulated via modulating the amperage applied to the motor, by the controller.
Speed is not effected, except as moderated by "load".
Application of more amps does not affect top speed, but is used solely to regulate torque

Your second sentence above contradicts your third sentence above. At full-speed, no-load conditions, it is true that current does not affect (not effect) top speed.
FA

I felt that the "... except as moderated by "load".", extended to encompass the next line.
Perhaps, "does not affect, maximum unloaded, top speed", might be more precise.

[neptronix]

Anyone with a turnigy watt meter, cycle analyst, etc will see this with any electric motor.

It's almost like electric principles... the road friction, aerodynamic drag, and gravity are resistance and require more current to overcome. The less resistance, the less current is needed.

At 62v X 40 amps, That's how i get the ~2500 watt constant number from my motor. When i am climbing a 7% grade at 30mph+ without pedaling, the controller is dumping ~2500 watts into my motor ( and the motor is shedding some percentage of that as heat, but we do rate things at the controller output on this forum, and so do manufacturers, so let's not get into semantics again. )

On a flat, at top speed, a hell of a lot less wattage is used. I see 1000 watts or so since i am not drawing 35-40 amps constant anymore.

[amberwolf]

Simplest - most basic, explanation of how a brushless motor works, is that it runs at full voltage, constantly.
Torque is regulated via modulating the amperage applied to the motor, by the controller.

Not quite. In the typical brushed or brushless controller (anything run via PWM), motor phase power is controlled by slicing up the voltage into pulsed bits. The wider the pulses, the more voltage, and the more average current, assuming no Back-EMF to counter that (meaning the motor is at slower than max no-load speed at that voltage).

Instantaneous phase current may be different from the average current, because of the inrush as the voltage is switched from zero to full voltage during each pulse. So phase current can be a lot higher than battery current, momentarily, even in a single-phase brushed controller.

Most controllers do not regulate torque at all, but rather just motor speed, thus the common abbreviation, ESC, for Electronic Speed Controller. Unless there is some way to monitor actual phase current, most controllers have no way of knowing what the motor torque is or should be, so they dont' attempt to regulate it at all.

They often can limit current, but usually either by monitoring battery current and limiting that by cutting back the width of the voltage pulses, or by monitoring battery current, calculating what phase current might be for that vs what the actual speed vs demanded speed is at that moment, and limiting the width of the voltage pulses based on that. Probably the first method is still the most common, even in brushless controllers (and it is almost always the way that brushed controllers typically do it, if they do).

Speed is not affected, except as moderated by "load".
Application of more amps does not affect, top, unloaded, speed, but is used solely to regulate torque.

Speed is the only thing that is directly affected, since more average voltage means higher average speed. A higher load on the motor may prevent the higher speed, and thus cause higher current draw.

When a motor is spinning, it generates voltage internally, whether or not voltage is applied externally. It's called BEMF or Back-EMF. The faster it spins, the higher this voltage is, based on the magnet strength (if any, otherwise on current thru a field winding) and the method of phase winding(s), etc.

If you are applying a voltage across a motor's phase(s), and it is spinning at some particular speed, the difference between the applied voltage and the BEMF (and things like winding resistance, inductance, etc.) determines the current flow at any instant.

So the faster the motor spins, the less current will be flowing thru it, vs slower speeds for the same conditions. So higher mechanical loads on the motor cause higher current flow.


Hopefully that helps.

If not, there are probably better explanations in this thread or one of the links in it:
viewtopic.php?f=30&t=240

[DrkAngel]

Not quite. In the typical brushed or brushless controller (anything run via PWM), motor phase power is controlled by slicing up the voltage into pulsed bits.

I had anticipated pulse width-duration modulation, or even multiple, "sized" pulses per "wave", but every example of, brushless motor, sine waveform, I could find, demonstrated a full width pulse?

Thanks!

[gogo]

The frequency of the pulses is a different issue than the percentage of on/off of the pulses.

[amberwolf]

I had anticipated pulse width modulation, or even multiple, "sized" pulses per "wave", but every example of, brushless motor, sine waveform, I could find, demonstrated a full width pulse?

With multiphase (such as in brushless RC or bike motors), explaining commutation is usually more important in various examples (especially animations), as it is harder for most people to grasp that part than it is the PWM, especially if they already have some understanding of brushed motors.

So they probably gloss over the PWM part, since adding that explanation (especially graphically) on top of the commutation, can get confusing if you don't already understand one of them.

But basically, PWM is still used for the control of the motors, regardless of brushed or brushless, even in sine-shaped multi-phase commutation (most ebike controllers use square or trapezoidal commutation, which is one thing that adds noise to many of the bike kits).

So it still chops up each commutation segment or block into a bunch of pulses, varying in width depending on how fast it's trying to command the motor to go. You may even see something called "block time" on programmable controllers, which basically tells the controller how long to use solid, non-PWM'd blocks of voltage for commutation segments during startup or other high-current events, before it starts cutting back on the voltage with PWM to keep overcurrents to a minimum or none.

Just imagine in any animated examples you've seen of say, 3-phase brushless commutation, that all the displayed waves are chopped up in varying-width pulses, to control the speed of the motor, as with full unbroken commutation blocks it's basically being commanded to go full speed.

[DrkAngel]

Have I got this right? Take 2.

Simplest - most basic, explanation of how a brushless motor works.
Power is regulated by modulating the amperage applied to the motor, by the controller.
(Typically, in a regulated, 3 phase arrangement. )
This is done via a series of full voltage pulses, the width, and quantity of which, determines the power input, (amps x battery voltage).
Additional amps supplied, increases motor "torque", but does not affect the "unloaded" ** top speed.
Amperage application is limited by controller capacity - or as a function of thermal decay.
(Electrical resistance of wire increases, as its temperature rises.
The application of more amps, shifts efficiency lower, as heat to torque ratio, increases.)
200% amp input might increase output to 150%. (Which Increases watt output, also.)

Additional, speed, as well as rated motor output - "watts", is obtained via the increase of supplied voltage.
Ex. Upgrading from 24v to 36v will enhance output, from 500w to 750w, which raises the torque curve, as well as increases the top "unloaded" ** speed by a full 50%.

Note: The "output" or "motor rated", "watts" is a fraction of the input "watts".
1000w input might produce a, usable, 750w output, = 3/4 = 75% efficiency rate.

** "Unloaded speed", is specified, to avoid, having to, explain-factor in, wind resistance, road load, component resistance etc., which are significant, measurable, factors during actual usage.

Please Note: I'm trying to keep this as simple-basic-understandable as possible!

[TylerDurden]

To keep it simple, don't use "amps" and "power" synonymously (that is misleading).

IIRC:

Controllers switch the power to the motor at a high rate and shift the percentage of on-time to off-time (PWM duty-cycle).
Whereas the motor windings act as an inductor, the average voltage in the motor is proportional to the duty-cycle; changing motor speed.
Whereas Power=Current*Voltage, lowering the average motor voltage via PWM results in a lower current drawn from the batteries (but higher current in the motor).

Brushless controllers also handle the commutation, sequentially sending PWMed power to each phase.

[torqueon]

I am trying to get my head wraped around this as well. I think what AW is descirbing kind of goes like this

Brushed motor PWM controll would look like this -----------

Brushless 3 phase PWM controll would look like this
Phase 1 --- --- --- ---
Phase 2 ...--- --- --- ---
Phase 3 ......--- --- --- ---

Setting aside controller and motor variables ( controller limts, motor load etc. ) Effective voltage is varied by the with of each pulse witch effect the amperage draw by the motor

Hope this make sense if I am wrong hear please Hollar

[TylerDurden]

http://adamone.rchomepage.com/guide5.htm

[torqueon]

Thanks Tyler

[gogo]

Effective voltage is varied by the with of each pulse

The width of the pulse alone (time) has to do with the frequency, voltage has to do with the ratio of on/off of the pulses.

Others have written about the effect of the frequency, IIRC it needs to be within a range, not too high or low.

[torqueon]

Understood! sorry for being vague

[DrkAngel]

Previously, it has been possible to buy the entire EZip bike for around $300, sadly, haven't seen anything near that, in almost 1/2 a year.
Present prices are in the $500 - $600 range.
Possibly some clearance items, come Fall, when sales slow down?

[gogo]

Previously, it has been possible to buy the entire EZip bike for around $300, sadly, haven't seen anything near that, in almost 1/2 a year.
Present prices are in the $500 - $600 range.
Possibly some clearance items, come Fall, when sales slow down?

Yes, I think winter is slow for ebike sales and they try to move the ones with lead-acid batteries. I've snagged an eZip for $225 on 12/12/08 and an EZgo for $275 on 12/24/09 from Amazon. I haven't seen an eZip for less than $300 since, though. I do a search for all Currie products whenever I'm on the Amazon site.

[DrkAngel]

Previously, it has been possible to buy the entire EZip bike for around $300, sadly, haven't seen anything near that, in almost 1/2 a year.
Present prices are in the $500 - $600 range.
Possibly some clearance items, come Fall, when sales slow down?

Yes, I think winter is slow for ebike sales and they try to move the ones with lead-acid batteries. I've snagged an eZip for $225 on 12/12/08 and an EZgo for $275 on 12/24/09 from Amazon. I haven't seen an eZip for less than $300 since, though. I do a search for all Currie products whenever I'm on the Amazon site.

I've, also, seen great deals at Walmart, Super Kids, Toys-R-Us.