Compressor Energy And Signal Flow - Danfoss Turbocor VTT Series Service Manual

2.6 Compressor Energy
and Signal Flow
Compressor Fundamentals
During normal operation, 3-phase power is required to be connected to the VFD at all times, even
if it is not running. Power is distributed through the following components to maintain compressor
operation:
• CCM Board
• PWM Board
• Stator
• CIM
• DC-DC Module
The order of power flow through the VFD components is as follows:
1. A 3-phase voltage source is provided to the VFD through the mains input terminal.
2. AC voltage enters the silicon rectifier diodes (SCRs).
3. The Soft Start Board limits the in-rush current at power-up by controlling the SCR gates.
4. DC bus voltage from the SCRs charges the capacitors.
5. The DC bus provides DC voltage to Inverter.
6. The Inverter converts the DC bus voltage into a variable frequency, 3-phase simulated AC
voltage to the Stator.
7. The VFD provides 462-683 VDC to the DC-DC Module.
8. The DC-DC Module provides 24 VDC to the CCM and 250 VDC to the Pulse Width Modulation
(PWM) Board.
9. The CCM provides 24 VDC to the CIM.
Refer to Figures 9 (System Architecture and Control Interface (Revisions A and B)) and 10 (System
Architecture and Control Interface (Revisions C and Later)) for a block diagram summary of the
energy and voltage signal flow through the Compressor.
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