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AX2500/2850 Motor Controller User’s Manual 31
Electrical Noise Reduction Techniques
has built-in capacitors and voltage limiters that will reduce these effects. However, should
the wire inductance be increased, for example by extending the wire length, these effects
will be amplified beyond the controller’s capability to correct them. This is particularly the
case for the main battery power wires (thick red and black cables).
Important Warning
Avoid extending the black and red Motor Power wires beyond their original length as
the added inductance may cause damage to the controller when operating at high
currents. Try extending the motor wires instead since the added inductance is less
harmful on this side of the controller.
Electrical Noise Reduction Techniques
As discussed in the above section, the AX2500/2850 uses fast switching technology to
control the amount of power applied to the motors. While the controller incorporates sev-
eral circuits to keep electrical noise to a minimum, additional techniques can be used to
keep the noise low when installing the AX2500/2850 in an application. Below is a list of
techniques you can try to keep noise emission low:
• Keep wires as short as possible
• Loop wires through ferrite beads
• Add snubber R/C circuit at motor terminals
• Keep controller, wires and battery enclosed in metallic body
Power Regeneration Considerations
When a motor is spinning faster than it would normally at the applied voltage, such as
when moving downhill or deccelerating, the motor acts like a generator. In such case, the
current will flow in the opposite direction, back to the power source.
It is therefore essential that the AX2500/2850 be connected to rechargeable batteries. If a
power supply is used instead, during regeneration the current will attempt to flow back in
the power supply potentially damaging it and/or the controller.
Regeneration can also cause potential problems if the battery is disconnected while the
motors are still spinning. In such a case, and depending on the command level applied at
that time, the regenerated current will attempts to flow back to the battery but since none
is present, the voltage will rise to potentially unsafe levels. The AX2500/2850 includes an
overvoltage protection circuit to prevent damage to the output transistors (see “Overvolt-
age Protection” on page 32)
Important Warning
Use the AX2500/2850 only with a rechargeable battery as supply to the Motor Power
wires (thick black and red wires). If a transformer or power supply is used, damage to
the controller and/or power supply may occur during regeneration. See “Using the
Controller with a Power Supply” on page 32 for details.