Electric Motor Torque Rpm Curve

T inlb p hp 63025 n 1.

Electric motor torque rpm curve.

As a current flows through the electric motor a related electrical charge causes an armature to rotate. Introduction of a vfd when the speed of an ac motor is controlled by a vfd hp or torque will change depending on the change in frequency. The engine is designed to make peak power and peak torque at very high rpm above 8 000 versus zero. The torque speed curves shown below are actual curves for the green maxon motor pictured at right used by students in 2 007.

In this overlay the shaded area reflects the accelerating torque available from the motor to drive the pump. T ftlb p hp 5252 n 1b. 1 ft lb f 1 356 nm. Other electric motors may in fact produce maximum torque throughout their entire operating range.

Thankfully in electric motors maximum torque is produced from the get go. N revolution per minute rpm alternatively. T inlb torque in lb f. For example the ac motor found in the tesla roadster 2008 produces near constant maximum torque from 0 to about 6000 rpm while maximum power occurs at about 10000 rpm long after torque begins to drop off.

Torque in imperial units can be calculated as. The roadster s redline is 14000 rpm. Full load torque flt the torque required to produce rated power at full load speed. Electrical motor power velocity and torque equations.

P hp horsepower delivered by the electric motor hp. Figure 1 provides a graphical illustration of these changes. The dc motor has a linear torque speed characteristic and power peaks at about half the maximum rpm. One is a plot of empirical data and the other was plotted mechanically using a device developed at mit.

The shunt motor also has a linear torque speed characteristic and similarly shaped power curve. By overlaying the torque speed curve of a pump and a motor one can verify that the motor is producing enough accelerating torque to drive the pump to full speed as shown below. The honda s2000 on the other hand has decent power 265 whp but low torque at just 163 lb ft. At full load torque the speed of the electric motor is slightly less than the synchronous speed as shown in the curve above.

Like pumps motors produce a torque speed curve of their own. That is why the shaft and frame of a 900 rpm motor are usually larger than those of an 1 800 rpm motor of the same hp. In practice a shunt motor cannot run at its peak power or torque as the currents involved are too large. T ftlb torque lb f ft.