RoboteQ AX2550/2850 Electrical Noise Reduction Techniques, Power Regeneration Considerations

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.

AX2500/2850 Motor Controller User’s Manual 31