operated with a controlled 90° phase difference. Pulse
width modulation is used for control of the output volt-
able pulse width generator, two drive subassemblies, a
step change adjustment circuit, and two silicon control
age of each static inverter. The outputs of the two
rectifier power stages.
inverters are fed into two Scott "T''-connected
transformers to provide a 3-phase output from a 2-phase
The power stage assembly contains capacitors,
transformers, and filters associated with the power stage
of the inverters.
The 4345A static inverter is enclosed in an alum-
inum cabinet (fig. 1-37), divided into three sections.
These are the meter panel assembly, the inverter module
assembly, and the power stage assembly. A resistor
A simplified functional block diagram of the model
subassembly is located on the back of the cabinet.
4345A static inverter is shown in figure 1-38. A brief
The meter panel assembly contains the instruments
discussion of the various components and circuits
and controls necessary for the operation of the equip
contained in the unit follows.
The inverter module assembly contains a control
circuit +30-volt dc power supply, a drive circuit
+30-volt dc power supply, an input sensing circuit, a
The oscillator (fig. 1-38) consists of a 1600-Hz
synchronizing subassembly, two variable pulse width
tuning fork controlled oscillator and a binary frequency
Figure 1-38.-Simplified block diagram of a static inverter.