DC Machines

DC machines are classified under two catagories:

• Permanent Magnet machines (typically under 5hp)
• Electromagnetic macines (larger scale)

The machine that the Electric Snowmobile will use is of the electromagnetic machine type, where a current is applied to an electromagnetic, called the field current. The field current is what induces the flux in the DC machine.

Electromagnetic DC machines have 4 different sorts of excitation:

• separate excitation
• self-excited shunt
• self-excited series
• compound

Another book: Electrical Machines and Power Electronics by R.E. Steven also discusses chopper control for DC machines and discusses the back EMF effect on the control system.