System Description; System Block Diagram; Ac Inverter Functions & Controls - Webasto 900 Installation, Operation And Maintenance Manual

2.0 System Description

2.1 System Block Diagram

The 900 architecture is shown in the following system block diagram (Figure
2.1). The AC Inverter connects to the utility via an isolation transformer. The DC
Converter and AC Inverter transfer power via an Intermediate DC Bus and
communicate via an RS-485 data bus. The DC Converter also communicates to
the 900 Remote Operation System via an RS-232 data link. The DC Converter
provides the DC interface to a load (or possibly two separate loads) in one of
two operating modes.
Isolation
Transformer
Utility Interface
Intermediate DC Bus
2.1.1 AC Inverter Functions & Controls
The AC Inverter interfaces the utility to an internal Intermediate DC Bus.
The Intermediate DC Bus voltage is regulated by the AC Inverter based
on the maximum voltage expected by the DC Converter connected. The
range for the Intermediate DC Bus is 750 - 910 Volts DC.
Circuitry designed into the AC Inverter monitors the utility to detect any
abnormalities. This is accomplished by measuring the frequency and
amplitude of the utility and verifying that it remains within the specified
range given in the Technical Specifications found below.
The AC Inverter operates under current control instead of the more
common phase control. This allows for a more robust interface to the
utility and linear response in the inverter dynamics.
references for the current are obtained from the utility waveforms, thereby
maintaining the AC Inverter as a true unity power factor interface
regardless of line harmonics.
11816-03-D
RS-485
AC
Inverter
Unit
Optional Data Collection Systems:
®
SmartGuard
• Contact Webasto for
•
National Instruments NIDAQ
•
Additional Information
Custom
•
Figure 2.1 – 900 System Block Diagram
Page 13 of 58
RS-232
High Voltage Interlock B
DC
Load B
Converter
Unit
Load A
High Voltage Interlock A
Webasto Charging Systems, Inc.
PC
In addition,