Installation manual

Danaher Motion Kollmorgen System Operation
SERVOSTAR
®
S and SERVOSTAR
®
CD Series 71
The SERVOSTAR uses a fully digital, pole placement current loop with high
bandwidth and a current loop sampling rate of 16 kHz (62.5 µS.). All
coefficients of the current loop are digitally calculated inside the drive for a
given set of motor and drive characteristics. The current loop also includes
adaptive gain terms to compensate for some non-linear effects.
The current loop incorporates electrical isolation for protection from the high-
voltage BUS. These current loops also convert the output voltage to a Pulse
Width Modulated (PWM) signal providing the highest efficiency possible. The
PWM center frequency can be 8 or 16 kHz according to the drive size.
COMMUTATION LOOP
This loop converts a single-phase current command signal into a three-phase,
position-modulated sine wave input to the current loops. The SERVOSTAR has
a patented sinusoidal wave form generator, which uses a technique called
Torque Angle Advance to get top performance out of its motors. The waveform
generator is part of the microprocessor and is updated at a 16 kHz rate. This
provides hi-fidelity sinewave commutation at both low and high velocities. The
sinewave output must be aligned to the back EMF (MOTORBEMF)
characteristics of the motor. This is why resolver or encoder alignment to the
motor is critical.
VELOCITY LOOP
The purpose of the velocity loop is to regulate motor speed. Like the current and
the commutation loops, the velocity loop is fully digital and uses the resolver or
the encoder feedback signals to calculate actual motor velocity. The command
for the velocity loop can come from a direct user input (OPMODE’S 0&1) or
can be the output of the position loop. The velocity loop is a digital sampling
system operating at 4 kHz.
The difference between actual and desired velocity is filtered through a
compensator algorithm and fed to the commutation loop. The SERVOSTAR
offers four velocity compensators (methods of regulating velocity) and are
selectable through the COMPMODE variable. The four are: Proportional-
Integral (PI), Pseudo-Derivative-Feedback with Feed-
Forward (PDFF), Standard
Pole Placement, and Extended Standard Pole Placement.