Dual-Frequency Braking Parameters - Siemens SINAMICS PERFECT HARMONY GH180 Function Manual

Advanced Operating Functions
8.9 Dual-Frequency Braking
goal of maximizing losses per ampere, this automatically minimizes the torque pulsations by
minimizing the loss-inducing current.
The dominant losses in a motor are conduction losses, proportional to I
ampere require a large value of R. The nominal resistance of the motor windings is fixed by the
design. The effective resistance depends on the frequency. The rotor windings are deliberately
designed to exhibit a strong "deep-bar" effect, so that their resistance that lies above a low
threshold increases roughly proportional to frequency.
The frequency of the loss-inducing vector set should be as high as possible for maximum
effective resistance. Since this high loss-inducing frequency produces negative slip, it will have
negative sequence. The maximum applied frequency is limited by the control bandwidth of the
converter, and also by the available voltage. However, because the loss-inducing vector set is
negative sequence, the rotor frequency will be higher than the stator frequency due to the
rotational speed.
8.9.2

Dual-Frequency Braking Parameters

Parameters for DFB
Refer to Braking Menu (3350) in Section Options for Stability Menu (3) of Chapter Parameter
Assignment / Addressing for parameters associated with this function:
• Enable braking (3360)
• Pulsation frequency (3370)
• Brake power loss (3390)
• VD loss (3400)
• Braking constant (3410)
Use these parameter settings to run the drive with DFB:
• Choose a pulsation frequency that avoids the mechanical resonant frequencies of the system
i.e. motor, shaft and load. A study of the mechanical system is required to determine the
resonant frequencies.
• Use brake power loss (3390) to set the initial value of motor losses. The default value is
satisfactory in most cases.
• Use VD loss (3400) to set the maximum voltage that is applied at the second, loss-inducing
frequency. This parameter cannot be set to a value higher than 0.5 pu. Adjusting this
parameter will have a direct effect on the achievable braking torque.
• Use braking constant (3410) to set the ratio of the power losses created in the motor to the
power absorbed by the drive during braking. Using the default value gives sufficient margin
and prevents the cell DC-bus voltages from increasing to trip levels.
246
2 R. Maximum losses per
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