Dear Alvaro,

I am assuming the block diagram of your model looks similar to my attachment (DriveSystem) and you are now about to implement the Modulator and the Inverter into your model? Based on this I will try to answer your questions.

1) "I'm not sure how to appropriately set the DC voltage level"

Generally speaking there is now such thing as setting the DC Link Voltage as it is a given parameter. However you are correct it is a parameter in your current controller. Assuming your current controller gives you voltages in the d-q reference frame you need to normalise those voltages with with VDC/2 (depending on your definition of the modulation index) to calculated the modulation index that is feed to the Inverter. To understand the basics about pulse width modulation and the relations between modulation index and DC-Link voltage may refer to:

Hava, "Simple Analytical and Graphical Methods for Carrier-Based PWM-VSI Drives" if you want to read a paper, otherwise to any PWM textbook.

2) " once I add the Inverter the DC voltage also plays a role in the voltage coming out from the current controller "

Yes those quantities are related. Consider the following example. You want to generate a specific torque T at a specific rotational speed wel, hence a specific mechanical power Pmech. Further consider a lossless system, hence Pel=Pmech. Now the electrical power Pel=3*Irms*Vrms is also a parameter of the voltage. Talking about the modulation index, this quantity is not affected as it is normalised with the DC-Link voltage.

"The voltage sent to the plant (either with or without the Inverter) should be only in function of the motor parameters and speed"

Neglecting any temperature influences, Rstator=0, field weakening or over-modulation and assuming fpwm >> fel the voltage in the dq-frame is only a function the controlled parameters (torque and rotational speed) and the machine parameters. However consider e.g. Rstator=!0 a specific torque (i.e. a specific iq current in normal operation) would lead to an additional voltage drop that need to be compensated.

I hope this was helpful

Pascal

Hi there;

The DC link voltage directly affects the power flow from the source to the motor. If the DC voltage has some ripple, for example, if it has been provided by a photovoltaic (PV) system, then the exchanged power between the source and the motor fluctuates. This causes other side effects such as harmonic distortion, opposite torques etc.