Siemens SINAMICS PERFECT HARMONY GH180, Function Manual

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3.3 Control Overview
SINAMICS Perfect Harmony™ GH180 drives maintain a simple "synchronous" control. It
coordinates the complex, cell-based power topology to produce a simple, multi-level pulse
width modulation (PWM) to the output connection of the drive. Basic operation is summarized
as follows:
1. The control sends a message to each power cell control via dedicated fiber links. The return
cell response, via a separate fiber, communicates cell status and diagnostics.
2. The cell executes the request by gating one switch pair, which results in one of the following
outcomes:
– Plus DC voltage
– Minus DC voltage
– Zero voltage
3. The cell control confirms that the switch pair gated.
4. The control confirms gating from:
– Output voltage divider
– Output Hall effect current transducer
• No two cells switch at the same time.
• The cell switching rate is low compared to the effective switching frequency of the VFD:
– Typically 600 Hz carrier frequency per pole results in 1200 Hz switching frequency per cell.
• The VFD effective switching frequency is calculated simply as:
– cell switching frequency * number of cells per phase
• The switching rate is constant over the entire output frequency range.
• The default control mode is open loop vector control (OLVC). Control modes Volts/Hertz (V/
Hz), closed loop vector control (CLVC) with encoder, and permanent magnet motor (PMM)
control without encoder are also available.
Control Description
3.3 Control Overview
Control Manual
Operating Manual, A5E50491925A
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