High Speed Operation - Emerson Powerdrive F300 Getting Started Manual

Table 8-2 Sample rates for various control tasks at each switching frequency
Level 1
Level 2
Level 3
Level 4
Background
8.4

High speed operation

8.4.1 Field weakening (constant power) operation
(Open loop and RFC-A mode only)
The drive can be used to run an induction machine above synchronous speed into the constant
power region. The speed continues to increase and the available shaft torque reduces. The
characteristics below show the torque and output voltage characteristics as the speed is increased
above the rated value.
Figure 8-2 Torque and rated voltage against speed
Care must be taken to ensure the torque available above base speed is sufficient for the application
to run satisfactorily.
The saturation breakpoint parameters (Pr 05.029, Pr 05. 030, Pr 05.062 and Pr 05.063) found during
the autotune in RFC-A mode ensure the magnetizing current is reduced in the correct proportion for
the specific motor. (In open loop mode the magnetizing current is not actively controlled).
Powerdrive F300 Getting Started Guide
Issue Number: 5
3, 6, 12 kHz
3 kHz = 167μs
6 kHz = 83 μs
12 kHz = 83 μs
250 μs
1 ms
4 ms
Torque
Rated
voltage
Rated speed
2, 4, 8, 16 kHz
2 kHz = 250 μs
4 kHz = 125 μs
Peak limit
8 kHz = 62.5 μs
16 kHz = 62.5 μs
2 kHz -500 μs
4 kHz - 250 μs
Current limit
8 kHz - 125 μs
and ramps
16 kHz - 125 μs
Speed
Speed
Open loop RFC-A / RFC-S
Current
controllers
Speed controller
and ramps
Voltage controller
Time critical user interface
Non-time critical user interface
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