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[sumfoo1]

I'm just trying to figure out if its a brushless dc or if its an ac setup or what they are doing with it.

Are there any cut-sheets on the motor?  Can it be run at a higher voltage/amperage ?

Can the motor controller be run at a higher frequency/rpm?

thank you,
Bill Hamilton

[frodus]

The motors are of their own design, but they are built by Motenergy. As far as higher current and voltage, I'd think they were designed with a little overhead, but that were likely designed for the voltage of the controller they're using, the Sevcon. They're proprietary of design, so I qould guess only Zero holds those cutsheets. I'd think with higher voltage and current, they would require active cooling for continuous duty. The magnets are glued to the rotor, so there is an RPM limit where the magnets could potentially fall off, or a heat limit where the glue would fail.

You could call it a Brushless DC motor (BLDC) but could also be called a Permanent Magnet AC (PMAC)... it mostly has to do with the inverter driving it. I'd refer to it as a PMAC Synchronous. It is not an Induction motor, which is asynchronous.

[nigezero]

Hi Frodus

Hey; now you have my intrigued; BLDC AND PMAC? The motor runs DC not AC, right?

[protomech]

The motor runs on AC (not necessarily a sinusoid). The DC in BLDC refers to the DC input to the controller/inverter, I think.

http://en.m.wikipedia.org/wiki/Brushless_DC_electric_motor

[frodus]

Long story:
It has to do with the inverter signal. PMAC gets a sinusoidal true AC input on 3 phases. BLDC gets stepped or sawtooth DC signals through 3 phases. The controllers both convert pure DC to 3 phase power to the motor.... The difference is how you drive it the 3 phases. Google a bit on it for a better understanding.

One motor can be used with both types of controllers but a true AC drive will be much more smooth.

The sevcon controllers that these bikes use are AC drives... Which can also drive induction motors btw. Early ones were bldc. IIRC, Kelly controllers were bldc early on.... Not sure about now.

Short story:
Just consider them PMAC because we primarily use AC drives to drive these motors. They do not use a DC signal anywhere on the motor side (except the encoder).

[trikester]

Tiny versions are the motors used to power most radio control model airplanes these days. They are driven by DC to 3 phase speed controllers just as the recent Zero bikes are (earlier Zero's are brushed DC series wound motors). Some have the center of the motor tuning (like Zero) and are called "in-runners" others have the outer case of the motor turning and are commonly called "out-runners". The out-runners are more popular with model flyers because more torque can be delivered from a smaller motor since the rotating part has the longest radius of the motor assembly. The motors are generally rated by RPM/VOLT in their model numbering system.

Zero's motors are "in-runners" which helps cooling because the electrical winding is on the outer case where there is more airflow and easier heat transfer. Zero's motors are transverse field which provides a shorter and more efficient path for the magnetic field than the more common axial field motors.

Trikester