Yaskawa DSD 406 - Manual (Page 8)

1 Introduction
3 DSD Drive Description
3/21/96
DSD Drive
Description
Regeneration
Capability
Flexibility
Control
Accuracy
The MicroTrac ® DSD is a complete digital system drive which provides
individual drive and system control in one compact package. This manual
describes two basic configurations, the DSD 406 (6SCR) Nonregenerative and
the DSD 412 (12SCR) Regenerative. All descriptions pertain to both
configurations unless specifically noted.
The nature of an electric motor is such that, if more torque is applied to the
motor by the load than is applied to the load by the motor, the motor will act as
an electrical generator, producing an electrical current. This phenomenon, called
regeneration, occurs anytime the speed of the motor is above the reference (or
preset) speed, sometimes referred to as an “overhauling load” condition. A
regenerative drive, such as the DSD 412, has the capability to feed the electrical
power generated by the motor back into the supply mains. Also referred to as
four-quadrant operation, it is this capability which requires that the DSD 412
contain a total of 12 SCRs, rather than the six included in the two-quadrant,
Nonregenerative DSD 406.
The drive uses two microprocessors, one for the Power Conversion Unit
circuitry, one for the Drive Control Unit circuitry, and is totally software
configurable to the application through a high level language. This provides
complete flexibility without having to make hardware adjustments. Interface to
other equipment is provided with Local Input/Output (I/O) or a high speed Local
Area Network. Use of the MicroTrac Local Area Network (LAN) means that a
single coaxial cable eliminates multiple conductor cables and provides high
noise immunity.
Extensive diagnostics and setup capability are provided through two
Control/Display Units. The Standard Control/Display Unit (SCDU) is mounted
on the Drive Control PCB and consists of a 4-1/2 digit numeric LED display,
four push buttons and LEDs. The SCDU can be used for all setup functions and
many diagnostics. The Portable Control/Display Unit (PCDU) is an optional
hand-held device that can be plugged into any DSD drive and used for all the
same functions as the SCDU plus some advanced diagnostics. The PCDU has
two lines of sixteen alphanumeric characters and a thirty-key keypad.
The distributed control architecture of the DSD systems means that each drive
performs its own regulation calculations synchronized to a common high
accuracy crystal master. Thus even minute crystal drift will not affect multiple
drive tracking. This allows a DSD system to maintain the drift between sections
at 0.00% steady state. The fully digital nature of the regulation means that an
individual drive can maintain a 0.00% average difference between set and actual
speed from no-load to full-load when using digital tachometer speed feedback.
Digital setup and performance assure exact process line and finished product
duplication shift to shift and month to month.