Beckman Couler ALLEGRA X-12/R, Руководство по обслуживанию, Страница: 58 / 83

Section 4: Schematics
Motor Driver Board
General
The Motor Driver Board (MDB) provides the necessary power handling components to
drive a three phase induction motor. These components can be organized into 5 sections:
Power Supplies, Interface, Timing, IGBT Drive, Power Module, and Fault Detection. All
circuits are referenced to the A.C. line input. Care should be exercised when connecting
test equipment.
Power Supplies
There are two power supply circuits: a high voltage power supply (HVPS), and a low
voltage power supply (LVPS). The HVPS converts the rectified A.C. line voltage to 400
volts D.C. The supply has soft start, over voltage and over current protection. The major
components of the HVPS are L4, C14 & 15, QF 24 & 27, and U22. The LVPS converts
the 400 volt output of the HVPS to +5 and +15 volts D.C. for use on the MDB. The
major components of the LVPS are T1 and U15.
Interface
Control and status signals are communicated between the Motor Driver Board and the
Control Board via opto-isolators located on the MDB. The inputs to the MDB are
three digital pulse width modulated (PWM) signals for controlling motor current,
drive enable for energizing the IGBT drive, brake, and fault clear (U5, 8, 9, 14, 17 &
18). The output signals are drive fault, drive on, over temperature, and an analog
voltage of the 400 volt supply referenced to logic ground (U6, 23, 24 & 25).
Timing
Components U2 and 19 delay the activation of the IGBT drivers to insure that the
high side drive does not conduct while the low side is still on. The delay is in the
order of 1.2 micro-seconds.
IGBT Drive
U20 translates the 5 volt level PWM signals to 400 volt amplitude. It provides the
necessary gate drive voltages for the IGBT bridge and some fault detection. It also
provides the gate drive voltage to drive a Brake Drive IGBT.
Allegra X-12/R, X-15R Service Manual 7/04 4-3