Inverter for motor controller

[mcstar]

Does anyone know of a motor controller that steps the voltage up like an inverter does to give you more speed from a lower voltage pack? I'd like to find a controller that can work with a 48V pack but boost the voltage up to around 70V to allow more speed from the same battery pack. I know some in Japan are doing this for very high speed motor controllers. This would be a boon for the electric bike/motorcycle club. Sure, you'd be trading current/range for voltage but in my case that's exactly what I want.

Any ideas?

 

[Link]

I think this was discussed elsewhere, and I don't recall anything like that being commercially available. It's certainly doable, though.

Alternately, the controller could be built to take the higher voltage, and you could have a separate component before the controller that boosts the voltage before it even gets there when activated.

 

[frodus]

Better to get a higher voltage controller, and more smaller cells to get the same amount of Wh capacity.

Or you could buy a huge DC-DC converter and step up from 48V to a higher voltage (not cheap).

Essentially, you have to design a high power switching power supply. I'm thinking you need something on the order of 1000W?

You'd still need a higher voltage controller for 70V... and by the time you're done getting something to step up the voltage, you'd be better off buying a new pack made up of smaller cells.

Its why I chose to install 10 12V 28Ah batteries in my motorcycle for 120V, and not go 72V with 6-50Ah batteries. I wanted higher speed.

 

[mcstar]

I'm thinking of building an "inverter controller". The basic circuit is simple.
http://www.rowan.sensation.net.au/electronics/stepup.html
I'm researching what it would take to bring it up in current capability to the point it would be useable at 1000w or greater. I've got a pile of inductors that can each deliver up to 3amps each, so I'm thinking about stacking 10-20 of them in parallel and building an appropriate array of mosfets to control them with. On the drive side, my plan is to use a Parallax propeller to generate the pwm control signal and a 10bit adc to monitor the voltage and current with.

 

[billvon]

Does anyone know of a motor controller that steps the voltage up like an inverter does to give you more speed from a lower voltage pack?

I'd use a simple nonisolated boost converter. It requires a massive inductor, some large caps, a switch (big MOSFET like the IRFB4110) and a controller. However, if your intent is simply to get more speed out of a BLDC motor, I'd just take a standard motor controller, take the controller part out, put your own controller in and do phase advance. More speed, no extra parts.