RT Box

The Fastest Real-Time Simulator for Power Electronics

With the new Nanostep® solver (to be released in Q4 2024) you can run real-time simulations on the RT Box with step sizes as low as 4 ns. It is a breakthrough for the testing of high-bandwidth control algorithms, supporting switching frequencies into the MHz range. This solver, exclusive to the RT Box, is included with all hardware models.

To use the Nanostep solver on your existing RT Box, upgrade the firmware at no additional cost here.

About the RT Box

The RT Box is a real-time simulator specially designed for power electronics applications. It is a versatile processing unit for both controller hardware-in-the-loop (HIL) testing and rapid control prototyping (RCP).

The RT Box operates hand-in-hand with a host computer running the PLECS Coder. The PLECS Coder translates a PLECS model into real-time capable C code to be compiled for running on the RT Box. The original PLECS model on the host computer can be connected to the RT Box simulation using an External Mode. This allows the user to visualize simulation results from the RT Box in the PLECS Scope and to tune parameters on the fly.

The RT Box hardware lineup offers solutions optimized for unique challenges faced when modeling various power converter types with sufficient fidelity. Library components are included for many standard topologies, or you can build your own. All units operate within the PLECS ecosystem preferred by engineers worldwide. The RT Box is available in four variants with different performance levels and a combination of CPU- and FPGA-based solvers for any circuit:

Performance Comparison
  RT Box CE RT Box 1 RT Box 2 RT Box 3
Processor Xilinx Zynq Xilinx Zynq Ultrascale +
CPU cores 2 x 1 GHz 4 x 1.5 GHz
↳ for simulation 1 3
Solvers
CPU-based
FlexArray -
Nanostep® 1 unit, 7.5 ns step size (fixed) 2 units, 4 ns step size (fixed)
Target audience Classroom and lab teaching Versatile and low cost for HIL and RCP Multi-core and FPGA for faster, higher complexity circuits Increased I/O for multi-level converters and microgrids

The complete technical specifications of the full RT Box family are listed in a comparison table.

The RT Box lineup offers a solution for any application.

Under the Hood

The RT Box processor consists of an FPGA and multiple CPU cores. The tight integration between the CPU cores and the FPGA also allows for ultra-low latency when data is exchanged between the Nanostep and the FlexArray solvers and the parts of the system that are simulated on the CPU cores. One of the CPU cores performs communication with the user while the remaining cores are used for the real-time simulation.

When running real-time simulations on the CPU cores, one can develop fully custom power stages, or simply save computational resources for parts of the system that don’t require fast update rates. For CPU-based simulations, the calculation time step is typically larger than 1 microsecond.

The RT Box 2 and 3 offer FPGA-based simulation that utilizes pipelined execution, along with the massively parallel processing. FPGA-based computations can achieve time steps as low as 250 ns, offering significant performance improvements for real-time applications.

High Precision Simulations with Nanostep

The Nanostep solver enables simulations with ultra-small simulation step sizes for controlling common power architectures, supporting MHz-level switching frequencies. Each simulation step includes sampling, calculation, and diode switch state determination. More information on Nanostep can be found in our related, early 2024 Bodo's Power Systems cover story.

The solver’s time step size allows highly accurate simulations, which is critical for applications requiring precise control. This is especially true for DC/DC converters with an inductive AC link, where the power transfer is very sensitive to the phase shift between the current and PWM signals. Common examples for this include resonant converters or dual active bridges, whose currents frequently change direction or enter discontinuous conduction mode. In these cases, insight into the current behavior between switching instances is essential.

The output current of a dual active bridge converter switching nominally at
1 MHz, simulated with the Nanostep solver using a 4 ns step size.

The table below shows an overview of the different solver types available for the RT Box family:

Solver Comparison
Device CPU FPGA
Solver type CPU FlexArray Nanostep®
Step size ≥ 1 us* ≥ 250 ns* 4ns / 7.5 ns (fixed)
Switching frequency ≤ 50 kHz ≤ 150 kHz ≤ 1.5 MHz
Availability RT Box CE, 1, 2, 3 RT Box 2, 3 RT Box CE, 1 (7.5 ns)
RT Box 2, 3 (4 ns)
Advantages Develop fully custom power stages and save computational resources for slower elements Faster simulations for various circuit elements and power modules High frequency applications and control precision
Use cases - All linear/switched components
- Thermal components
- Loss model calculations
- Magnetic domain circuits
- Electrical machines
- Control blocks (including
C-scripts and state machines)
- Converters based on Power Module blocks, especially multi-level
- Passives
- Sources
- Meters
- Breakers
Specific topologies**:
- DABs
- LLCs
- PSFB
- Other DC/DCs
- 1/3ph VSIs 2/3-level
- PFC/Vienna rectifiers
*Model size-dependent
**Additional topologies not currently supported by Nanostep
may be customized or developed for it upon request.

Connections for the RT Box

Analog I/O

The analog I/Os in the RT Box feature 16 bit resolution with simultaneous sample and update. The inputs and outputs can be adjusted to common industrial voltage ranges. All I/Os are protected against ESD, short circuiting and accidentially applied overvoltages.

The analog inputs are differential to suppress common mode EMI. If needed, they can be operated in a single-ended manner.

Digital I/O

The digital I/Os are typically used for high-fidelity PWM capture and PWM generation, but can also provide general purpose functionality or special low-level communication. Such communication currently includes SPI master and incremental encoder. The digital I/Os are compatible with 5 V and 3.3 V signal levels.

Interface Cards

For fast and easy connection of external hardware a set of breakout boards and interface cards is available.

Tutorials

A collection of videos will assist you with setting up and operating the RT Box.

Pricing and Availability

Visit our store for further information. For a binding quote and delivery times in your area please contact us at info@plexim.com.