Switched Reluctance Motors For Ebikes? http://machinedesign.com/article/the-switch-to-switched-reluctance-1211 A quest for energy efficiency has fostered development of switched reluctance motors that are inherently simple and can supply variable speeds. They can be more efficient than induction motors and work at variable speeds. They are also inherently simple. For a time, they powered Maytag Neptune washing machines. Switched-reluctance (SR) motors were developed in the 1800s but, apart from a few embedded-drive applications, they have not been widely applied. Their optimum operation depends on relatively sophisticated switching control, something not economical until the advent of compact but powerful solid-state power devices and ICs. Now, with a new emphasis on energy efficiency, switched-reluctance motors may be ready to take a more prominent role in appliances, industrial equipment, and even off-road gear. http://www.mlittle.com/appliance/neptune/neptune2.htm Motors are a vital part of most appliances. An important consideration of the Neptune is that the drive motor be capable of high torque, high speed, soft starts, rapid reversal, and tight control. Criteria such as this can be expensive to obtain, driving up the cost of the appliance. Maytag enlisted Emerson Electric to help with the design of a motor and controller which could meet these requirements at a low cost. They selected a switched reluctance motor because of the control available, and the low manufacturing cost of the motor. Since the rotating component of the motor (rotor) has only vanes and no magnets or windings, it is cheaper than other motor designs. Unfortunately, this type of motor requires more sophistocated electronics for control; however, the electronics could be developed more cheaply than another type of motor which could perform under the same criteria. Another issue is the need for position feedback from the motor to the controller. This motor uses a tachometer device to inform the motor control board of the current rotor position, so that the controller may energize the proper phases at the proper times.