Hello members!
I've been lurking here on your forum for some time now. I've been looking at EV possibilities for the last... <drum role/> week.
One of the first questions I have in developing my project is exploring considerations tractor solutions.
I hear that AC solutions have the following characteristics: (FYI corrections / clarifications welcome)
I became interested in AC Synchronous type solutions, ideally the DC-excited solutions, of which an standard alternator is quite similar.
Look at these Permanent Magnet Synchronous Motors (PMSM): http://www.boschrexroth.com/dcc/Vor...anguage=EN&VHist=g97568,g96068&PageID=p146808
Simply contemplating the engineering solution I believe it addresses the first two issues in the list regarding AC solutions above.
Economics aside, imagine an A4 chassis with one of the 47.6 Kw MSS142F-0700 powering each wheel at a 5 to 1 ratio. The site is wrong in that Max RPM is 10K rather then 28K, FYI.
With 225/55 R17's (84 inches circumference), that means at nominal RPM (7K) the car would cruise at a cool 111 MPG with 255 HP and 958 ft of torque.
I'll have to work out the power source for this... glass-mat batteries maybe.
On a side note, the nominal specifications are at 540V DC on the inverter bus. The motors are rated to 750V max... The is running such high voltage a serious problem, even in a well designed EV solution? The motors rated current at 7K is 68 x 4 Amps and the system need some multiple, n, of 45 12V cells to obtain 540V. The question then becomes how many sets of 45 cells to wire in parallel. I clearly need to examine the power source requirements for this solution _way_ more thoroughly.
Any other considerations?
Thanks in advance for any comments.
I've been lurking here on your forum for some time now. I've been looking at EV possibilities for the last... <drum role/> week.
One of the first questions I have in developing my project is exploring considerations tractor solutions.
I hear that AC solutions have the following characteristics: (FYI corrections / clarifications welcome)
- low end torque (as in below 1/3 of the motors nominal RPM rating) is poor.
- the rotor phase must slip behind the voltage curve to generate torque, the result is a degraded power factor resulting in systemic inefficiencies.
- DSP type solutions required for motor control.
I became interested in AC Synchronous type solutions, ideally the DC-excited solutions, of which an standard alternator is quite similar.
Look at these Permanent Magnet Synchronous Motors (PMSM): http://www.boschrexroth.com/dcc/Vor...anguage=EN&VHist=g97568,g96068&PageID=p146808
Simply contemplating the engineering solution I believe it addresses the first two issues in the list regarding AC solutions above.
Economics aside, imagine an A4 chassis with one of the 47.6 Kw MSS142F-0700 powering each wheel at a 5 to 1 ratio. The site is wrong in that Max RPM is 10K rather then 28K, FYI.
With 225/55 R17's (84 inches circumference), that means at nominal RPM (7K) the car would cruise at a cool 111 MPG
with 255 HP and 958 ft of torque.I'll have to work out the power source for this... glass-mat batteries maybe.
On a side note, the nominal specifications are at 540V DC on the inverter bus. The motors are rated to 750V max... The is running such high voltage a serious problem, even in a well designed EV solution? The motors rated current at 7K is 68 x 4 Amps and the system need some multiple, n, of 45 12V cells to obtain 540V. The question then becomes how many sets of 45 cells to wire in parallel. I clearly need to examine the power source requirements for this solution _way_ more thoroughly.
Any other considerations?
Thanks in advance for any comments.
