Control methodologies of sinamics VFD

Good Evening ,

In CU240-E2 manual, I came across the control methodologies of sinamics VFD.

0: U/f control with linear characteristic

1: U/f control with linear characteristic and FCC

2: U/f control with parabolic characteristic

3: U/f control with parameterizable characteristic

4: U/f control with linear characteristic and ECO

5: U/f control for drives requiring a precise freq. (e.g. textiles)

6: U/f control for drives requiring a precise frequency and FCC

7: U/f control for a parabolic characteristic and ECO

19: U/f control with independent voltage setpoint

20: Speed control (encoderless)

22: Torque control (encoderless)

For which kind of applications I have to select which methodology.

Best Regards

TN Sudheer

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Split from v/f control of multiple induction motors (different name plate).

0: U/f control with linear characteristic

Operating multiple motors with one inverter drive, this is the only control strategy to use.

Tractor

Thnx Tractor

What about remaining methodologies, which kind of applications we can use other ctrl methodologies..

Regards

TN Sudheer

I suppose it is good to know the capabilities built into the Sinamics drives.  However, you are asking the question kind of backwards.  You pose a control problem to your local Siemens distributor / sales engineer and ask for a suggested solution when it is outside the normal control schemes you are very familiar with.  They then suggest the right hardware, and control strategy to accomplish the task.

If you use the Siemens Sizer application (either online or downloaded executable), it can help you understand the various control capabilities as you pose different mechanical requirements.

For example, controlling a press brake, conveyor, cam-emulation, geared setup, compressor, fans and so on all have different open loop characteristics.  The control strategy tends to work best when the open loop control matches the open loop performance.

That's what the various control methods offer.

TNSudheer

Thnx Tractor

What about remaining methodologies, which kind of applications we can use other ctrl methodologies..

Regards

TN Sudheer

0: U/f control with linear characteristic, U/f or voltage proportional to frequency this respects the increase in motor coil impedance with supplied frequency. this is a basic operation. A basic control for most asynchronous motors.

1: U/f control with linear characteristic and FCC, same as above, but the flux in the motor is regulated, and is proportional to load or current. Light loads benefit from a reduction in motor flux. Reducing power loss for lightly loaded fans or conveyors perhaps.

2: U/f control with parabolic characteristic, same as (0) above, but the Voltage against frequency is not linear, and forms a parabola. This respects the load created by a centrifugal fan or pump, where high torque at low speeds is not required, or beneficial. Permits the drive power rating to respect this load shape, e.g. fan or pump.

3: U/f control with parameterizable characteristic, here the Voltage / frequency relationship can be programmed, useful for synchronous motors where the necessary V/F is available for that motor. High speed routers with special V/F characteristic require this.

4: U/f control with linear characteristic and ECO, here the V/F is modified by the inverter drive according to load, low mechanical loads will have a reduced Voltage against frequency, thereby reducing the power consumption and motor current. This can be seen to function with a light load after a change in setpoint, full control is available for the setpoint change, and after a slight delay the current consumption will reduce.

5: U/f control for drives requiring a precise freq. (e.g. textiles), here the precision for speed control and setpoint is more precise.

6: U/f control for drives requiring a precise frequency and FCC, as above with FCC.

7: U/f control for a parabolic characteristic and ECO, a combination of the two controls FCC and ECO.

19: U/f control with independent voltage setpoint, Voltage can be controlled independently of frequency. For example, it is possible to connect the Voltage setting to an analogue input, and it is then possible control the motor slip, and motor torque if you are careful?

20: Speed control (encoderless), speed can be regulated with high accuracy by calculation, and slip is eliminated. Sometime referred to as 'Sensorless Vector control'. The drive requires precise measurements of the single motor, in this case, in order to operate the control algorithm.

22: Torque control (encoderless), as above but regulating the 'torque' to set values. E.G maintaining tension on a supply umbilical, or web tension.

Note:

Voltage / Frequency, this control or relationship is necessary to regulate the current through the motor coil, because the impedance is proportional to applied frequency. The drive provides this function as a basic control. 

Most asynchronous motors are designed to operate at fixed frequencies 50Hz, and 400Volts for example, from this the current and power developed can be known. When the inverter drive then applies a low frequency, the coil impedance will be proportionally low; it is therefore necessary to apply a reduced Voltage at this point, or the current will be excessive, whilst still maintaining the required motor torque.

Tractor