FC_PowerStageFrequencySet - General Information
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Type: |
Function |
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Available as of: |
SystemInterface_1.32.6.0 |
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Versions: |
Current version |
Set power stage frequency.
The power stage supports the frequencies of 4, 8, and 16 kHz. The default frequency is 8 kHz. This functions allows for the switch-over to 4 or 16 kHz.
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Switch-over to |
Advantage |
Disadvantage |
|---|---|---|
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4 kHz |
Increasing the rated current of the Lexium 62 |
Reduced running smoothness |
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16 kHz |
Improved running smoothness |
Reduction of the rated current |
NOTE: Refer to your drive hardware guide to validate the rated currents corresponding to the desired power stage frequency.
NOTE: Every phase-up of Sercos results in re-establishing the default factory setting of 8 kHz.
With the modification of the power stage frequency, the internal current amplifications, the overload monitoring of the power stage, and the stray power and energy measurements are automatically adjusted.
The call of the function is only permitted as of Sercos phase 3. In the other Sercos phases, the call has no effect.
For Double Drives, note that only one frequency can be set for both drives.
A new frequency value that is sent to one of the two drives is automatically sent to both drives.
The set power stage frequency is displayed in the parameter LXM62DxS.PowerStageFrequency in the parameter folder "control loop" in kHz.
The parameter type is AS (Sercos parameter). The factory setting is 1 (= 8 kHz). The value 0 is displayed on virtual axes.
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UNINTENDED EQUIPMENT OPERATION |
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oOnly switch over the power stage frequency if the parameter ControllerEnable of the corresponding axis is false. oVerify, and adjust if necessary, the filter settings for VelFilter and CurrRefFilter. |
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Failure to follow these instructions can result in death, serious injury, or equipment damage. |
During the first approximations, the current control loop appears like a delay in reaching the reference current. The higher the power stage frequency is set, the lesser the delay.
The difference in the delay is higher between 4...8 kHz than between 8...16 kHz.
The filters VelFilter and CurrRefFilter have a filter effect that also takes effect on the current loop control. By mechanics, where the filter effect of the filters VelFilter and CurrRefFilter is necessary, an increasing of the PWM-frequency can require an increasing of the filter parameters. Therefore the reduction of the filter effect of the current loop control can be compensated.
NOTE: By 4 kHz there is a higher possibility that the diagnostic message 8107 "Overcurrent" occurs. This can be compensated by setting the parameter VoltageFeedForwardMode to the value "Dynamic behavior of the control loop / 3". In addition, make sure that the higher-level control loops (speed controller and position controller) have a stable control behavior.
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Input |
Data type |
Description |
|---|---|---|
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i_stAxisId |
ST_LogicalAddress |
Logical address of the drive |
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i_etFrequency |
ET_PowerStageFrequency |
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Data type |
Description |
|---|---|
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DINT |
0: No error detected -1: Logical address of the servo amplifier is invalid -5: Frequency is not supported -464 and -431: Change-over of the frequency is not supported by the drive -445: Timeout of the service channel |
When operating external supplier motors, it must be observed that the controller can only generate a limited electric frequency.
The resulting speed depends on the PowerStageFrequency and can be calculated as follows:
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Formula |
Condition |
|---|---|
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Speedmax=96000 (rpm) / pair of poles |
At PowerStageFrequency 8 kHz or 16 kHz |
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Speedmax=48000 (rpm) / pair of poles |
At PowerStageFrequency 4 kHz |
If this speed of rotation is exceeded, an impairment of the motor can occur. In the case of multi-pole motors (for example, torque motors), this limit can be reached at relatively low speeds. Motors that can reach a higher maximum speed may only be operated to the limit specified here. The maximum speed can be limited using the parameter UserMaxVel.
