AC50 and medium sized cars

5588 Views 11 Replies 6 Participants Last post by JRP3, Feb 21, 2013

Richard Wood

Discussion Starter · Feb 3, 2013

The AC50 seems to have the highest profile of the AC Motors but I read varying anecdotal reports of its capability around hills. Chinese BLDC motors are looking very promising as an alternative.

On my commute I have a hill climb that has to happen. My car is a BMW 318ti. I am doing all my calculations at the GVMR 1555kg just in case.
The hill is a 4.6 degree angle (8 percent incline). I have calculated this to require 30-35Kw, and as it is 2km I will need to hold this for 90 seconds. If I do 1:1 through a transmission to the 4.44 diff then 3000 RPM will do 80km/h - sounds perfect. (Side question: I haven't decided whether to modify the auto transmission or put in a two speed transmission yet, but understand the former may add significant losses - any idea how bad?).

Either way, is this motor up to it? The chart says it can do over 40Kw at 3000 and at that point still has its 150 maximum torque.
http://hpevs.com/Site/images/jpeg/power-charts/pdf/ac50_102v_650a_metric.pdf

However people quote 50kw as its peak performance. So is this graph all peak readings? If so, how long is it reasonable to expect a motor to operate at peak for? And what if one added a water cooling plate to this motor (and to the controller), what impact would that have?

Richard

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tomofreno

· #9 · Feb 6, 2013

Richard Wood said:
The AC50 seems to have the highest profile of the AC Motors but I read varying anecdotal reports of its capability around hills. Chinese BLDC motors are looking very promising as an alternative.

On my commute I have a hill climb that has to happen. My car is a BMW 318ti. I am doing all my calculations at the GVMR 1555kg just in case.
The hill is a 4.6 degree angle (8 percent incline). I have calculated this to require 30-35Kw, and as it is 2km I will need to hold this for 90 seconds. If I do 1:1 through a transmission to the 4.44 diff then 3000 RPM will do 80km/h - sounds perfect. (Side question: I haven't decided whether to modify the auto transmission or put in a two speed transmission yet, but understand the former may add significant losses - any idea how bad?).

Either way, is this motor up to it? The chart says it can do over 40Kw at 3000 and at that point still has its 150 maximum torque.
http://hpevs.com/Site/images/jpeg/power-charts/pdf/ac50_102v_650a_metric.pdf

However people quote 50kw as its peak performance. So is this graph all peak readings? If so, how long is it reasonable to expect a motor to operate at peak for? And what if one added a water cooling plate to this motor (and to the controller), what impact would that have?

Richard

I don't believe you stated at what speed you desire to climb the hill, unless you meant the 80 kph. I can tell you at 40 to 45 mph (67 to 75kph) it requires about 65Ah and about 6825Wh to climb 19 miles (32km) up a 4.5% grade in my about 2250 lb (1023 kg) Swift with an AC50, so about 359Wh/mile or 216Wh/km. It requires about 200A current and 21kW average power, and around 25 -30 minutes to reach the top. Motor temperature at top is about 55C in 70 F (21C) ambient, so about 1.06C/km temperature rise.

Now, make that a 3400 lb vehicle and 2 km long 8% grade and I would expect around 800Wh/mile and around 50kW power at the same speed, and about a 2*1.06*50/21 = 5C temperature increase. Peak shaft power of the motor with the 650A controller should be around 60kW with a 115V nominal pack. Hopefully this is within +/-30% of actual performance you would get, but no guarantees.

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