d'Oh!
Of course! Since the BEMF is one of the main "problems" With the BLDC motor, you could probably get away with one controller and one 3 phase rectifier. Hmmmm, I wonder about stability - would there be any wierd resonances when feeding something back to itself like that.
Regarding the "power" column, you're right - I'm having an impossible time corroborating any of those numbers. Another company gives the "enclosed" value of roughly 50%:
AWG20: diameter: 0.032" 10.15Ohms/kft 11.0A max 7.5A enclosed
Wire-Gauge Ampacity - Transwiki
Wikipedia had a great NEC chart, unfortunately no ampacity numbers below AWG14:
American wire gauge - Wikipedia, the free encyclopedia
I looked to see what ORNL did with the Prius tests. One thing that was VERY interesting is the 2010 Prius motor used the same number and gauge of wire per phase:
Number of wires in parallel: 12 (chart on pg. 46 of 2010 Prius evaluation)
Wire size, AWG: 20 (chart on pg. 46 of 2010 Prius evaluation)
They then did a huge test on the magnets, and then set up the motor on a dyno with a bunch of thermocouples. The locked rotor test shows the torque with current and electrical position. This is graphed on pages 60 and 61, I'll list the peak results:
75A 120 degrees (electrical) 80 Nm
100A 135 degrees (electrical) 110 Nm
125A 135 degrees (electrical) 130 Nm
150A 135 degrees (electrical) 155 Nm
200A 135 degrees (electrical) 195 Nm
250A 135 degrees (electrical) 215 Nm
These locked rotor tests were done with a DC input current for just enough time to measure the torque. Similar tests were done with the Camry and Lexus LS 600h at much higher current levels (note- they have different wiring).
Note that the rotor and stator dimensions are different from the MGR we're using, BUT the wiring is the same. Thus, we can't accurately use the torque numbers, BUT consider how much MORE current (250A vs 108A) they used for the test.
- E*clipse
Quote:
Originally Posted by thingstodo
That's why I suggested 2 MGRs and 2 controllers. The first is in motor mode, the second in regen or generator mode. Connect to the same battery pack. If you are removing 50 kw and regen of 40, you only need to 'top up' 10 kw to keep the system running.
Or you could run for a while just on battery.
And monitor the heck out of everything? Sounds like a workable plan.
I'm not sure about the 'power' column. I've never seen anyone use currents that low for the cables involved. For example, #16 lists 22A for chassis and 3.7A for power. That's your house wiring. It'll take 15A all day, every day. #14 is used for outside plugs - 32A chassis, 5.9 for power.
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