
8I20 1
GENERAL
DESCRIPTION
The 8I20 is a low cost 2200W 400V three phase torque mode/voltage mode
amplifier for synchronous permanent magnet servo motors (Brushless AC servo) up to
approximately 3HP. The 8I20 will supply peak currents of 30A.
High side logic and gate power are derived from the low side allowing a wide
operational bus voltage range (24 to 400VDC) and host communication when bus voltage
is off. Low side power can be 5V +-5% or 8-40 V unregulated. 3750V RMS isolation is
provided between high and low side electronics. Hall effect current sensing is used along
with high speed bus voltage monitoring for an accurate, stable, and fast current/torque
control loop.
Host communications are provided by a low overhead 2.5 Mbps serial protocol over
isolated RS-422 link. Link speed allows up to 5 KHz update rates from host.
High side over current sensing protects the IGBT module from line-line and
line-ground faults. A brake output capable of 15A drive is provided. The brake output can
be driven at a presettable overvoltage setting.
Even though it uses a 40 MIPs DSP, the 8I20 is a 'dumb' amplifier suitable for
integration in host based motion control systems. The 8I20 requires reference angle and
requested current/torque or voltage values sent from a host controller. The 8I20 uses the
requested torque and reference angle to control the current loop. The 8I20 can echo status
information to the host controller including bus voltage, phase currents, card temperature,
and other parameters..
Both smart (SoftDMC) and host based (HostMot2) multi axiscontrollers are available
for the 8I20. Up to 32 axis of motion can be controlled by a single low cost FPGA based
controller.