User manual

IDX Manual (V1.16 / December 3

, 2008) 14

5.2 Connecting Motor and Power Supply

Power supply

IDX

keep distance

short

Figure 5.2: Connecting Motor and Power Supply

5.3 Power Supply Requirements

The power supply voltage shall be in the limits as given in the chapter 4 under operational ratings.

Please note that there is no protection against reverse polarity or too high voltage. The power supply

typically should be within a range which fits the motor requirements, as described in chapter 5.1.1.

When using supply voltages near the upper limit, a regulated power supply becomes a must. Please

ensure, that enough power filtering capacitors are provided in the system (1000µF for each ampere of

RMS motor current or more recommended), in order to absorb mechanical energy fed back by the

motor in stalling conditions. In larger systems a zener diode circuitry might be required, when motors

are operated at high velocities.

The power supply should be designed in a way, that it supplies the nominal motor voltage at the

desired maximum motor power. In no case shall the supply value exceed the upper / lower voltage

limit. To ensure reliable operation of the unit, the power supply has to have a sufficient output

capacitor and the supply cables should have a low resistance, so that the chopper operation does not

lead to an increased power supply ripple directly at the unit. Power supply ripple due to the chopper

operation should be kept at a maximum of a few 100mV.

Therefore we recommend to

a) keep power supply cables as short as possible

b) use large diameter for power supply cables

c) if the distance to the power supply is large (i.e. more than 2-3m), use a robust 4700µF (IDX

7505) or 2200µF (IDX) or similar additional filtering capacitor located near to the motor driver

unit. Choose the capacitor voltage rating fitting to the maximum operating voltage.

The overall power rating mainly depends on the motor used and on the mechanical output power, i.e.

the motor velocity and desired torque. As a thumb rule, a 42mm class motor will require a 10W (short

motor) to 20W (long motor) power supply, while a 57mm motor will require 15W to 30W, when

operated at maximum rated current and low velocities. Operation at very high velocities will increase

the power demand up to the double value.