lorenfb said:
So the motor is very similar to the Spark's motor as discussed here;
http://www.mynissanleaf.com/viewtopic.php?f=10&t=6198&start=900
lorenfb said:
Reviewed the basic specs of the 2016 Spark verses the 2016 Leaf:
Torque (lb-Ft) HP (kW) Battery (kWh)
Spark: 327, 97 (130 HP), 19
Leaf: 190, 80, 30
The LEAF has more torque than the Spark at zero speed, but less at highway speeds, as discussed
here:
RegGuheert said:
It seems clear from looking at these curves that the Spark EV has LESS torque at the axle than the 2011 LEAF. The LEAF has 280 Nm at the motor which equates to 2222 Nm at the axle after the 7.9377 reduction gear. That's 1622 ft*lbf of torque at the axle! This compares with 1700 Nm (at the axle) for the Spark EV. Clearly the 400 ft*lbf spec for the Spark EV is the motor torque.
But the difference is in power. The LEAF can only maintain its maximum torque up to about 25 MPH, while the Spark EV can (nearly) maintain it up to about 40 MPH. At 40 MPH, the LEAF is down to somewhere around 1350 Nm of torque.
Basically, a high-torque, low-speed motor can reduce drivetrain losses at all speeds by reducing the switching frequency of the inverter and hence the switching losses (which
I have estimated to approach a 1-kW constant draw in the LEAF) while also reducing the eddy-current losses in the motor at higher speeds.
Switching losses will likely be greatly reduced in future BEVs by moving from IGBT switches to MOSFETs (likely SiC, but possibly Si), but the eddy-current losses in the motor are improved greatly by GM's approach.