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 Inductive  Coil
The Addition of an Inductive Coil

The simplest DC electric drive system  used a battery pack switch and a motor.  When you close the switch, over 1000 amps of current would flow in the circuit, producing so much torque that it would break parts (axle, transmission, drive shaft or mounting brackets).  So resistors were added to the early systems; this wasted energy but minimized damaging parts.  Modern controllers are better because there is an electronic switch that turns on and off so fast that it can control the current through the motor and the torque it produces.  Most of the time, the motor and controller work well, but it is difficult to identify exactly how they will work together. 

 With the large number of systems we sold last year, now in operation, some customers (~1%) have run into some operating problems, such as a periodic burp in the system.  Dave Mosher of Custom Electronics has determined that these problems were due to low inductance in the system.  Inductance can be added to the system by making an inductive coil.

The instructions for making an inductive coil are:
Make a coil of 2/0 cable using about 10 ft of cable by wrapping it around a 2x4 or  PVC pipe; then wire tie the coils together.  Remove the 2X4 or pipe.  You want 8-10 coils.  Connect this coil between A2 and S2 on the motor (CCWDE), replacing the existing short cable that connects the field and armature in series.  If the motor is set up for CWDE, then the terminals will be A1 and S2. This coil does not need to be beside the motor, so you have some flexibility in location.  Use quality lugs and heat shrink.

The addition of an inductive coil eliminated the operating problems that these few customers encountered.  Others found that the motor and controller ran cooler, indicating more efficient operation.

Adding an inductive coil to the motor circuit will be beneficial for all of our customers, because it will decrease the heat in the controller and motor and possibly provide additional range.  To date, the inductance coil has been implemented on a few vehicles with no negative results.  We are fine tuning the existing system.  

Let us know how it works for you.!

EVA - Customer Service is No. 1 !  
4  October 2010