FUNDAMENTALS
Service Manual M4 - M10
29.12.1999
Page
11
Rectifier: Three phase rectifier converts three phase AC voltage into an
appropriate DC power for operation of voltage source inverter. Rectification
factor for three phase/six pulse system is 1, 35.
DC capacitor bank: The DC capacitor bank stores energy (1/2CU2) to reduce
voltage ripple in the DC bus and to provide stable voltage source.
IGBT inverter: The three phase inverter converts DC power to three phase AC-
power for the motor. IGBT bridge produces a symmetrical three phase PWM
(Pulse Width Modulated) AC voltage.
Power supply: The internal power supply provides power for all control
circuitry. The switch mode power supply takes energy for operation directly
from DC bus.
Measurements: Output current from the inverter is measured from all three
phases by the current sensors (CT). Signals from the sensors are processed
to appropriate level for an accurate motor control and for protection from
fault current in output phases. Voltage in the DC bus is measured for proper
motor control and for protection.
Gate drivers: Gate drivers amplify control pulses for IGBTs in the inverter.
Gates of the IGBTs are pulsed with +/-15V. Negative pulse is important to
achieve proper blocking of the IGBT. Complete and proper blocking of the
IGBT in case of detected fault current is required.
The motor and application control block: This is software based function,
where motor is controlled through blocks Motor control ASIC, Gate drivers,
IGBT inverter, according actual values of measurements as instant current
and instant voltage in DC bus with parameter settings and current
requirements from process control.
Motor control ASIC: Motor control ASIC gets commands from the Motor and
Application control for calculation and determination of switching logic for the
inverter bridge.
Cooling fans: Cooling fan forces air flow through heat sink to dissipate heat
from power semiconductors.
Control panel: Provides man to machine interface for parameter settings, to
read actual values, to give commands for the drive and after all control
operation of the drive. Operation through RS232 serial link and removable
construction provides flexibility for remote installation.
RS 232 link can be used in communication with PC if needed.
I/O Control block: I/O Control block provides first of all interface for process
control and next, isolation from main circuitry to process interface. High
