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Installation and testing of Field Weakening on the Warp9 motor!
Feb. 9, 2011
I have been giving allot of thought to adding "Field Weakening" to the Warp9 motor.
I was able to find this description on a diesel locomotive site.
"Field weakening is an optimized version of phase advance.
Instead of simply energizing the stator fields to keep 90 degrees ahead of the rotor,
field weakening also produces a stator field component that opposes the rotor’s magnetic field.
This reduces the stator back EMF, which acts as a braking force."
This means to me that if I can make F.W. for my Warp9 motor that I should be able to get more power from the motor
because I am now using less power in the fields of the motor.
So, there should be more power available to turn the armature.
The things that are required to do this are made up of:
Field Weakening Shunt
Field Weakening Contactor
RPM driven controller
I am going to use a Tachometer with an adjustable shift light as my RPM sensor to trigger the initiation of the F.W. process.
I am going to use an a main contactor for the F.W. Contactor.
I am still looking for more information on the proper resistance of the F.W. Shunt.
I have been in contact with Mr. Hamstra Pres. of NetGain Motors Inc.
Mr. Hamstra gave the field coil resistance as 3.93 Milli Ohms per set on the Warp9 motor (PT# 00-08219).
Here is the plan..
When the motor RPM shift point is reached the tachometer's shift light circuit will activate an additional relay to send power
to send voltage to the F.W. Contactor coil, (contacts close).
The F.W. shunt now conducts a set amount of current away from the field windings of the motor effectively reducing the motor's Back EMF.
When the motor RPM's drop below the RPM setpoint the shift light turns off and the F.W. circuit shuts off, the motor reverts back to full field current.
I bought a tachometer with an adjustable shift light on Ebay. I have removed the back cover and it looks like I can add a relay inside the tach case
and have an output wire go to the F.W. contactor coil.
Feb. 12, 2011
Posted Modified Tachometer wiring design for field weakening on the Wiring Diagrams page.
Feb. 13 2011
Here is the foot print diagram of the 9 VDC, PCB relay, Radio Shack # 275-0005
I will mount this relay inside of the Tach. can and it will control the large contactor for the FW.
Disassemble the tachometer by removal the the rear tach. cover (can) and it looks like I can fit everything inside.
Traced circuit of the PC board and made a general diagram and how the relay will wire into the shift light.
Feb. 15, 2011
Desoldered and removed the 330 Ohm resistor and replaced it with a 1K Ohm resistor.
Soldered a 1N4001 diode across the coil of the relay.
Soldered 2 wires to go from the relay coil to the PC board across the 1K ohm resistor.
Soldered 2 more wires to go from the common relay contact pin and N.O. pin of the relay, these 2 wires will go to power the Large FW contactor.
Soldered the wires to the PC board and glued the relay to the back of the Adjustable Resistor to hold it from rattling when the can is in place.
Reassemble the tach and the can and slip a short length of plastic tubing over the wires coming out the back.
Next Wiring Diagrams.
