Hardware Overview

Figure 1 presents the modular structure of PELab and elaborates on the hardware usually used in each unit. As shown, a PELab unit includes several electronic and power electronic modules and components as below:

1. Power electronic modules with smart gate drivers. The gate drivers automatically consider a dead time if it does not exist in the input PWM signals

2. EMC filter with pre-charge relays and resistors

3. Inductors

4. Isolated voltage and current measurements

5. Analog and digital multiplexers

6. Embedded ARM microcontroller equipped with a 5″ touch screen

7. External current and voltage measurements

8. Cooling system, including several fans on the back panel

9. Power and signal (digital and analog) terminals

10. Power, control and protection switches/selectors

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Figure 1. Hardware configuration of a PELab unit

PELab supports various power electronic topologies including three-phase six-switch (PELab-6PH), H-bridge for modular multilevel converters (PELab-MMC), T-type NPC (PELab-TNPC), and three-phase NPC (PELab-NPC).

A typical schematic of a PELab is shown in figure 2. According to this schematic, each PELab-6PH includes two three-phase power modules, which are located back to back. Thus, the DC link of the modules can be connected to each other for AC to AC applications, such as grid-tied drives and wind turbines. Each power module has its own EMC filter, where the pre-charge relays (RL1 and RL3) and resistors are also assembled. The neutral connection for each power module is also provided with its EMC filter and can be used by activating the neutral relay (RL2 for power module1 and RL4 for power module2). The inductors are located between the EMC filters and the power modules on each side. Since the inductors are islanded, they can be easily bypassed or separately used in other power electronic systems.

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Figure 2. Schematic diagram of the PELab Hardware including the power modules, EMC filters, pre-charge relays and resistors, neutral relays, inductors, and measurement nodes

The front panel illustrated in figure 3 provides several features for control, protection, and monitoring purposes as below:

1. DB37 connectors dedicated to interfacing OPAL-RT real-time simulators and rapid control prototyping equipment. It is worth mentioning that OPAL-RT simulators and RCPs can be directly connected to these terminals without any hardware or software modification.

2. Standard fifty-position D-sub connectors allocated to interface OP8666 or any other RCP controller

3. Isolated BNC terminals for monitoring the analog signals measured by the internal and external voltage and current sensors. These signals can be transferred to an RCP unit or HIL simulator for real-time control and simulation purposes.

4. Indicates the locations of the analog signal measurements. These labels are also mentioned in figure 2 to highlight the measurement nodes.

5. Mode selection control knob

6. Fault enable and disable switches

7. Fault status indicators

8. On/Off button of the power supply used for feeding the control and protection systems

9. Embedded controller and its touch screen

10. Communication terminals that cover Sync, CAN, RS485, and fiber optic

11. USB port for in circuit programming and debugging

12. USB port for data, including the measured signals. This USB terminal is also considered for monitoring the measured signals using the intelliSENS oscilloscope.

13. Manual power contactor to connect and disconnect the outputs of the power modules

As shown in figure 4, several features and connectors, such as the power terminals, external voltage and current measurements, and cooling systems are located on the back panel of the unit.

The list of the features located on the rear panel is as below:

1. The power supply input for the protection and control systems

2. Auxiliary power supply terminal, which can be used to power up other PELab units

3. Input and output terminals of the power modules, EMC filters, and inductors

4. User guide for power circuit connections

5. Earth terminal

6. Inputs and outputs of the manual contactor

7. External voltage sensor terminals

8. External current sensor connectors

9. Cooling fans