I was shopping for a controller and I noticed "booster" listed.some are 1.1 some 1.5.What is "booster"?

[James340]

 

[marvin78]

According to Bing ->

'In the context of an e-bike controller, the term "booster" typically refers to a feature that increases the current (amperage) supplied to the motor temporarily to provide extra power. This means the controller allows a higher current to flow to the motor for a short period, giving you a boost in power when needed.'

Sorry, Bing first said it would increase voltage... so I had to ask him 'voltage or amperage'. Then it spat out the above

 

[James340]

According to Bing ->

'In the context of an e-bike controller, the term "booster" typically refers to a feature that increases the current (amperage) supplied to the motor temporarily to provide extra power. This means the controller allows a higher current to flow to the motor for a short period, giving you a boost in power when needed.'

Sorry, Bing first said it would increase voltage... so I had to ask him 'voltage or amperage'. Then it spat out the above

I googled using every different wording I could think and got nothing.

 

[marvin78]

Bing isn't google, it's much more error prone ( but you can get more answers from it ).

That's btw why I specifically added it's an AI generated answer, it might very well be wrong ( as I said, it first 'explained' to me it would increase voltage to the motor... which it obviously can't ).

Bing seems pretty adapt at giving answers it thinks you want to hear, and less so with if those answers are always 100% factually correct.

I hadn't seen the term 'booster' either, it's usually not a ratio but just a 'peak power' listing vs the nominal power afaik.

 

[James340]

The description on AliExpress is often not accurate.These controller's are listed as 36/48 volt.I opened one and it has 100 volt caps in it.

 

[marvin78]

Yeah the 36v controller which came on my first cheap cn ebike was also perfectly happy running on 48v, but since it had 60v caps a 52v battery would be the real max.

The caps aren't the only factor in how much current it would be able to supply reliably though, most of these cheap controllers use a low number of ( lower quality / worse cooled ) mosfets so you can more easily blow through one.

.. but all those name brand controllers are so expensive right. But then again, considering a good controller can change the feel of your bike completely while also giving you much more ease of mind for not getting left stranded at the least opportune moment somewhere. And a good controller can be kept between projects, so it can be a worthwhile investment.

Nothing wrong with a simple KT controller though as long as you pick something with matching specifications for your bike.

 

[James340]

I bought these controllers for 2 low powered bikes.36&48 volt at 20 amp limit.

 

[amberwolf]

That's btw why I specifically added it's an AI generated answer, it might very well be wrong ( as I said, it first 'explained' to me it would increase voltage to the motor... which it obviously can't ).

Voltage change is actually what the controller does to modulate motor operation, for these 3phase BLDC motors.

It increases current by increasing the average voltage across the windings (longer PWM cycles), and decreases current by decreasing average voltage (shorter cycles).

There can also be a function (called "block time" in certain controllers) that essentially turns off PWM (not really, but effectively) to provide the highest possible average voltage (and thus current and power), for a certain *very short* amount of time. Most controllers cannot do this very long for a number of reasons, mostly heat in the FETs. Normally it only applies at startup from a stop, and above a certain speed it doesn't operate, but it could also be done at the start of any full-throttle application.

FOC controllers can also change the "angle" of the current vs the rotational position of the rotor vs stator, which can also affect the current flow and torque.


It's possible that "booster" is the old "block time" function under a new name. If so, it's only going to apply for a second, or fraction thereof, typically.

It could be something else entirely--even the old throttle "gears" control, which just gave you three levels of control over the amoutn of throttle response, and despite the typical naming that went up to over 100% couldn't actually do any more than 100% of what the controller was capable of.

Or it could be some new way of marketing the controller to sound better than it actually is.

 

[marty]

View attachment 363863

Manufacturer? Model number? With that information I would research answer to question.

 

[amberwolf]

Yeah the 36v controller which came on my first cheap cn ebike was also perfectly happy running on 48v, but since it had 60v caps a 52v battery would be the real max.

The caps aren't the only factor in how much current it would be able to supply reliably though, most of these cheap controllers use a low number of ( lower quality / worse cooled ) mosfets so you can more easily blow through one.

The main limiting factor is the FETs themselves, along with the board layout and gate drive setup. A good layout will minimize spikes at turn off/on, but non-optimized layouts (possibly made worse by low (or is it high?) inductance motors) can have serious spikes that go well beyond the actual system battery voltage, and that can destroy FETs even if the battery voltage used is well-within the FET ratings.

Secondarily, the FETs' spec'd voltage limit for non-counterfeit parts of well-known/established brands (IRF, etc) can be trusted as an actual limit for those. But there are a lot of counterfeit parts out there, that aren't even remotely the same as the part number put on them. Then there are all the "genuine" parts that are re-used from something else, with who knows what kind of abuse history. Then there's the "genuine" parts but from manufacturers that have little or no QC, so there's not really any guarantee that they meet the design specs (which are often not even available to check to see what they *should* be rated for).

A further limit to controller "overvolting" is the low voltage power suppply LVPS--it takes battery voltage and converts it to the 5v,. 12v, etc that are used inside the controller and for accessories like halls and throttle and PAS. Some of these (linear regulators like LM series) are easy to find the limits for, but some are designed as SMPS that are a bit harder to reverse-engineer to figure out which parts limit you to how much voltage. Linear ones you can just stick resistors in front of to drop the voltage, as you can calculate or measure how much current it will draw for the output it gives...SMPS types may not draw the same kind of constant current, and any changing current will change the voltage across the resistors, which also changes the voltage across the regulator...if it exceeds the part limits, pooof.

Caps aren't too much of a limiting factor because they're so easy to swap out, so you don't even have to look at what voltage they're rated to see if a controller is overvoltable, until you have already verified all the other things are good to go.

 

[marvin78]

Voltage change is actually what the controller does to modulate motor operation, for these 3phase BLDC motors.

I didn't realize my controller came with a boost converter built in.

It increases current by increasing the average voltage across the windings (longer PWM cycles), and decreases current by decreasing average voltage (shorter cycles).

Ahh, average voltage != total voltage. Or at least that's how I would see it because if someone said to me 'my controller sends more volts' I would think the controller would send a higher voltage then it got from the battery'.

I probably should think: my controller limits the voltage based on duty cycle, so when someone ( or an AI ) tells me it increases voltage, it actually means it limits the duty cycle less resulting in higher voltage.

I'm a bit thickheaded with semantics, I hope you don't hold it against me.

There can also be a function (called "block time" in certain controllers) that essentially turns off PWM (not really, but effectively) to provide the highest possible average voltage (and thus current and power), for a certain *very short* amount of time. Most controllers cannot do this very long for a number of reasons, mostly heat in the FETs. Normally it only applies at startup from a stop, and above a certain speed it doesn't operate, but it could also be done at the start of any full-throttle application.

FOC controllers can also change the "angle" of the current vs the rotational position of the rotor vs stator, which can also affect the current flow and torque.


It's possible that "booster" is the old "block time" function under a new name. If so, it's only going to apply for a second, or fraction thereof, typically.

If 'block time' was a function limited by time, wouldn't it be given in a measurement of time instead of a ratio? Or do you think 1.1 and 1.5 are the seconds matching that old function perhaps ( probably ).

It could be something else entirely--even the old throttle "gears" control, which just gave you three levels of control over the amoutn of throttle response, and despite the typical naming that went up to over 100% couldn't actually do any more than 100% of what the controller was capable of.

Or it could be some new way of marketing the controller to sound better than it actually is.

Sounds like a link to the controller itself would be helpful

 

[marvin78]

The main limiting factor is the FETs themselves, along with the board layout and gate drive setup. A good layout will minimize spikes at turn off/on, but non-optimized layouts (possibly made worse by low (or is it high?) inductance motors) can have serious spikes that go well beyond the actual system battery voltage, and that can destroy FETs even if the battery voltage used is well-within the FET ratings.

Secondarily, the FETs' spec'd voltage limit for non-counterfeit parts of well-known/established brands (IRF, etc) can be trusted as an actual limit for those. But there are a lot of counterfeit parts out there, that aren't even remotely the same as the part number put on them. Then there are all the "genuine" parts that are re-used from something else, with who knows what kind of abuse history. Then there's the "genuine" parts but from manufacturers that have little or no QC, so there's not really any guarantee that they meet the design specs (which are often not even available to check to see what they *should* be rated for).

A further limit to controller "overvolting" is the low voltage power suppply LVPS--it takes battery voltage and converts it to the 5v,. 12v, etc that are used inside the controller and for accessories like halls and throttle and PAS. Some of these (linear regulators like LM series) are easy to find the limits for, but some are designed as SMPS that are a bit harder to reverse-engineer to figure out which parts limit you to how much voltage. Linear ones you can just stick resistors in front of to drop the voltage, as you can calculate or measure how much current it will draw for the output it gives...SMPS types may not draw the same kind of constant current, and any changing current will change the voltage across the resistors, which also changes the voltage across the regulator...if it exceeds the part limits, pooof.

Caps aren't too much of a limiting factor because they're so easy to swap out, so you don't even have to look at what voltage they're rated to see if a controller is overvoltable, until you have already verified all the other things are good to go.

Seems I was lucky then That controller had a 36v/48v sticker on it with none of them crossed out so I assumed it could handle both also based on that.. and a replacement was dirt cheap I even found the exact same one's on Ali for if I would blow through a mosfet ( even if it was a 48v controller, it was a low quality 6 mosfet one where the mosfets weren't particularly well cooled either. Maybe there were thermal vias in the pcb but the heatsinks were pitiful.

 

[amberwolf]

Seems I was lucky then That controller had a 36v/48v sticker on it with none of them crossed out so I assumed it could handle both also based on that..

For using a controller within the ratings printed on it, it's pretty likely it can handle those, and is "switchable" between them, either automatically or manually. (not always, but...usually).

 

[marvin78]

Well, it didn't have any negative effect on charging or charge status on the display so I guess that does point to it automatically detecting the type of battery connected. LVC was at 39v and soc indication matched with a 48v discharge curve.

Never really thought about it then, but if it wasn't universal and self switching, it would have tried to run that battery dead.

 

[amberwolf]

I didn't realize my controller came with a boost converter built in.

That's what these controllers essentially are--buck / boost converters.

Ahh, average voltage != total voltage. Or at least that's how I would see it because if someone said to me 'my controller sends more volts' I would think the controller would send a higher voltage then it got from the battery'.

Using the motor's own inductance, it actually *can* do that, for individual PWM pulses. I don't know how many of them actually do this intentionally.

IIRC the old Adappto controller used a motor winding (or two?) as an inductor to turn itself into a battery charger, though I never looked into the specifics of how it did the process.

I probably should think: my controller limits the voltage based on duty cycle, so when someone ( or an AI ) tells me it increases voltage, it actually means it limits the duty cycle less resulting in higher voltage.

That's the general idea.

I'm a bit thickheaded with semantics, I hope you don't hold it against me.

No, I just try to clarify whenever I see information that has some technical point that isn't complete, for the benefit of anyone that wants to know. For most purposes, these things don't really matter to the end-user--stuff works, or it doesn't.

If 'block time' was a function limited by time, wouldn't it be given in a measurement of time instead of a ratio? Or do you think 1.1 and 1.5 are the seconds matching that old function perhaps ( probably ).

If the ratio is for a block-time-like function, it is more likely a ratio between the non-block-time normal operation, and the block-time operation output.

Sounds like a link to the controller itself would be helpful

Maybe, but without engineering info on how it is designed, and how the software is written and setup from the factory, it's difficult to tell much about what various features actually *do* (or even what features it *has*) on many controllers, because terminology is so often used wrong on these ads, intentionally or not, and many ads don't provide much if any technical info. Most of the sellers have no idea what they're selling, and copy the ad info from other ads for "similar" devices, so what you see in an ad may not even be the actual info on the controller being sold.

 

[E-HP]

This subject comes up occasionally, and each time, I read up more on it, but it’s never conclusive, at least not enough to explain the ratio. Most labels show 1:1, and others shoe 1:3, or 1:5. There seems to be both methods boosting voltage on the input side of the controller, or on the output side. There’s some papers describing using capacitors and a boost converter to increase the input voltage for a limited time. Phase voltages maxes out just under battery input voltage at full throttle, so boosting the input voltage should increase the voltage to the motor, and therefore power.

I recall a recent thread on a mobility scooter with a controller with that type of function, boosting power for 5 seconds or so (like to get over a curb). The description sounded a lot like the above (voltage boost).

Kelly uses the “boost” in the context of regen, but doesn’t seem its related to the controllers mentioned above. Anyway, just been reading and taking notes since it would be nice to figure it out. I’ve noted, among ebike controllers, the spec seems to be pretty consistently listed on DC MOTO/JN controllers, and s lot of generic controllers.

Google ai states
“In a DC motor controller, a "capacitor discharge boost" refers to a circuit design where a capacitor is rapidly discharged to deliver a high voltage pulse to the motor, effectively creating a temporary boost in power to achieve a desired action like quick acceleration or high torque at startup, often used in applications where the initial power supply might not be sufficient for demanding motor operations.”

 

[amberwolf]

This subject comes up occasionally, and each time, I read up more on it, but it’s never conclusive, at least not enough to explain the ratio. Most labels show 1:1, and others shoe 1:3, or 1:5. There seems to be both methods boosting voltage on the input side of the controller, or on the output side. There’s some papers describing using capacitors and a boost converter to increase the input voltage for a limited time. Phase voltages maxes out just under battery input voltage at full throttle, so boosting the input voltage should increase the voltage to the motor, and therefore power.

I recall a recent thread on a mobility scooter with a controller with that type of function, boosting power for 5 seconds or so (like to get over a curb). The description sounded a lot like the above (voltage boost).

There are a number of commonly used ways to "boost voltage" external to the controller, as long as the ocntroller's input can handle the whole range. This can boost total motor power as long as total input power to the controller from this boost also increases. If it increases input voltage by decreasing available input current, it doesn't increase the available motor power.... So the most effective external boosts would do so by "adding a battery" in series with the existing one, rather than by a fixed-power boost converter (the motor controller is a variable-power boost converter already). ****


Boosting the output pretty much requiires the controller itself do that, for 3phase BLDCs. (brushed singlephase motors may have more options for post-controller voltage boosting, but that doesn't provide any more power to the motor, since it only has whatever the controller was outputting to work with).


****fixed-power input voltage boost converters that decrease current availablilty to create the voltage boost probably only really increase the speed capability of the motor (up to the available power at the input).

Kelly uses the “boost” in the context of regen, but doesn’t seem its related to the controllers mentioned above. Anyway, just been reading and taking notes since it would be nice to figure it out. I’ve noted, among ebike controllers, the spec seems to be pretty consistently listed on DC MOTO/JN controllers, and s lot of generic controllers.

It'd be nice if terminology was used the same way for the same thing by everybody, instead of marketing and other clueless ad-copy / webpage and manual -makers just using them however they like, or making up new ones or taking unrelated ones and using them.

Poor translation from one language to another, and back again, and again, doesn't help.

But if you can make a list of who uses which terms in what way, it might help in varous threads here (like this one), if the items in question are on the list.

Google ai states
“In a DC motor controller, a "capacitor discharge boost" refers to a circuit design where a capacitor is rapidly discharged to deliver a high voltage pulse to the motor, effectively creating a temporary boost in power to achieve a desired action like quick acceleration or high torque at startup, often used in applications where the initial power supply might not be sufficient for demanding motor operations.”

While I'm no expert on them by any means, I'm not aware of any controller / motor system that does this. I don't suppose it named any of them? I'm curious how they'd design for this....