User Manual

Selecting and Connecting the Encoder
Advanced Digital Motor Controller User Manual 129
Connecting the Motor
An AC Induction motors have just 3 power wires which must be connected to the control-
ler’s U V and W terminals. The connection order is not important. However, swapping any
two motor connections will make the motor turn in the opposite direction.
Selecting and Connecting the Encoder
A speed sensor must be used to measure and control the motor’s slip when running in
Constant Slip mode and Torque/Speed FOC mode. This is done using an incremental en-
coder. Most AC induction motors come with a built-in quadrature encoder. These encoders
typically have a relatively low number of counts. 32 or 64 Pulses Per Revolution (PPR) rota-
tion are typical values. A low count encoder results in low frequency pulses.
When using encoders up to 128 Pulses Per Revolution, the controller evaluates the rota-
tion speed by measuring the time between encoder pulses. This results in measurement
with a resolution of 0.1Hz even at full speed.
When using encoders with higher PPR, speed is measured by counting the number of
encoder signal transitions over a 10ms period. Prefer therefore a high-count encoder of
around 1000 PPR for better speed measurement resolution.
Unless otherwise noted in the product’s datasheet, all Roboteq’s AC Induction Motor
Controllers have to pull up resistors that can connect to open collector encoder outputs.
Controllers also have capacitors to help filter out any electrical noises that contribute to
fake encoder readings.
Encoder
4.7K
10nF
GND
5VOut
A
B
Controller I/O Connector
Testing the Encoder
To test the encoder, use the PC utility to enable the encoder and set its number of Pulses
Per Revolution (PPR). Go to the Utility’s Run tab, enable the Encoder Count in the chart.
Make a full turn of the motor shaft by hand. Verify that the counter has changed by the
number of PPR * 4.
Prior to enabling Constant Slip or FOC Modes, operate the motor in open loop Volts per
Hertz mode with slip control disabled. To disable slip control, set the encoder as No Action
in the configuration menu.