2.1 Diagram and Nomenclature of the Virtual Test Bench Components

The virtual test bench implemented in the real-time simulator is shown in Figs. 1 and 2.

Figure 1: Virtual test bench implemented in the real-time simulator; rotor short-circuit configuration

Figure 2: Virtual test bench implemented in the real-time simulator; adjustable rotor resistance configuration

These are the main elements in the bench:

• A DC machine with independent excitation:
  • Two adjustable voltage sources SC1 and SC2 for armature and field when the DC motor is used to drive the induction machine (see Fig. 1).
  • An adjustable voltage source SC2 for the field of the DC machine and a fixed load resistance R_ch when using the DC motor as a generator to represent a variable load to the induction motor (see Fig. 2).
• A wound rotor, three-phase induction machine.
• Command switches (K1) (K2) (K3) allowing users to connect the induction machine’s stator to several devices (see Fig. 1):
  • A three-phase, wye-connected, adjustable autotransformer SA1 linked to an infinite bus with a user defined constant frequency and voltage (the default value is f_s = 60 Hz).
  • A PWM (pulse width modulation) inverter with variable voltage and frequency powered by batteries
  • An adjustable DC voltage source SC3 in series with two fixed limiting resistors used to measure low resistances in the asynchronous machine stator.
• Command switch (K4) opens the induction machine’s wound rotor windings or connects multiple devices (see Fig. 2):
  • A three phase short-circuit module.
  • A set of adjustable external resistances that can connect in series with rotor windings using switch (K5);
• A detachable mechanical coupling (K₆) on the shaft connecting both machines.
• A protection system composed of fuses connected in series with all the windings from both machines: (F_if ) (F_ia ) (F_ia ) (F_ib ) (F_ic ). Fuse ratings and their I²t were adjusted according to both machine specifications. These devices have the same behavior as normal fuses and allow students to safely interact with the setups.

The measurement devices associated with the virtual test bench are only represented by their measured quantities: DC voltages V_a & V_f, DC current I_a & I_f, rotational speed of shaft N and torque T_u, RMS value of the voltage line-line U_s and line current I_s, total active and reactive power P & Q exchanged at the asynchronous machine’s stator.
Oscilloscopes not shown on Fig.1 allow users to view or capture waveforms and instantaneous values.

Detailed descriptions of the adjustable elements (power supplies and contactors) accessible to the user on the panel of the simulator are provided in section 3 of this document.

2.2 Electric Machines Nameplate Ratings

Table 1: Induction machine nameplate ratings

Table 2: DC Machine Nameplate Ratings