Navitas AC conversion diode requirement

[Sergio]

That comment definitely refers to the Solenoid coil diode since a shorted or backwards diode will cause the driver inside the Controller to drain excessive current.

The diode on the Solenoid big posts is only used on the Alltrax XCT and the purpose is to prevent a controller failure due to a voltage spike if the Solenoid contact were to open while the cart was in Regen brake.

That diode gets wired with the cathode (band) towards the battery so it always conducts current from Controller to batteries when the solenoid contacts are open.

The pre-charge resistor on the big studs is only used on the Curtis OEM controller.

The Solenoid Coil (inductor) is a current storage device and when you interrupt the power it will attempt to continue the current flowing at the same rate it was before being interrupted.

As the device that interrupts the current flow (switch or transistor) opens and increases in resistance towards "infinite", it causes the voltage on the device to go up drastically (V=R * I).

That causes an arc on a regular mechanical switch but it can damage the silicon junction in transistors.

There is no detrimental reason in a golf cart system from having flyback protection on the Solenoid coil (that is only an issue in specialized high speed switching systems).

If that Controller has some sort of built in protection they should flat out say it in printed on their directions.

Some Solenoids have built in diodes and others have "economizer" PWM circuits in their coils that cannot be disabled so it obviously does not cause issues.

That is my technical argument in favor of having the flyback diode.

[Bobbob]

Thanks Sergio for your explanation.


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