LUT based PMSM control reference ; Vdc input method

Hello,

I m using LUT based PMSM control reference for pmsm foc simulation. In the vdc input port, i want to give battery voltage which will change w.r.t SOC of the battery. What input method should i choose in the diolog box.

• Specify via dialog — Specify the fixed reference voltage Vdc using the parameter DC bus voltage, Vdc (V).
• Input port - use 3D LUT (voltage slice based) — Specify the variable reference voltage Vdc using the input port Vdc. When using this option, the block computes the reference current data for the given voltage by using a 3-D lookup table (LUT) based on voltage slicing.
• Input port - use 2D LUT (scaled-w based) — Specify the variable reference voltage Vdc using the input port Vdc. When using this option, the block computes the reference current data for the given voltage by using a 2-D LUT based on motor speed (ω) scaling.

There are these 3 options. For 2D lut and 3D lut what should be the input.

Is there any example for the 2D LUT and 3D LUT based voltage input.

Thanks

Answer 1

[Raghunath Rachabattuni]

To add to the above answer, the 3D LUT option creates a 3D table for both id, iq values that depend on three parameters, namely, torque, speed and voltage. The voltage becomes third dimension of the LUT (3D matrix). The voltage array for the third dimension can be provided as voltage breakpoint vector.

Alternatively, you may also select the 2D LUT(scaled Omega based) for few cases which involve less voltage variation. This essentially implements an algoritm that uses the 2D LUTs for id, iq (which depend on speed and torque, and calculated at the Reference Vdc value from the mask's text input field) at a reference Vdc to compute the id, iq reference values at a input Vdc (from the input port). This is close to the above method, when the motor's Rs is less.

the 2D LUT option saves memory when this block is used for code-generation. The 3D LUT option works well even when the motor's resistance is high.

Hope this helps.

Answer 2

[Supraja]

Since your battery voltage changes with respect to the State of Charge (SOC) of the battery, it is recommended to use the "Input port - use 3D LUT (voltage slice-based)" option in the LUT-based PMSM control reference dialog box in Simulink. This option allows you to specify the variable reference voltage Vdc using the input port Vdc and compute the reference current data for the given voltage by using a 3-D lookup table (LUT) based on voltage slicing.