Real-Time Simulation of Electric Drives & Systems with RT … · RT-LAB Presentation Overview ... RT-LAB Simulator +-Motor Plant Model Testing Real Controller with Real-Time Plant

Opal-RT Technologieswww.opal-rt.com

Real-Time Simulationof Electric Drives & Systems

with RT-LABSimon Abourida

[email protected]

March 3, 2005

Opal-RT Technologies /sa 2

Real-Time Simulation of Electric Drives & Systems with RT-LAB

Presentation OverviewIntroduction

Power Electronics and DrivesReal-Time Simulation

Real-Time SimulationModesRequirements and challengesRT-LAB Simulator

Typical ExampleChallenges and ProblemsQuestions and Answers

Introduction

Power Electronics & Drives

Real-Time Simulation

RCP & HIL

Typical Example


Introduction - Electric Drives

Electric Drive:Plant

Electric Motor (and load)Power Electronics Converter

ControllerRegulator (control algorithm – current, speed and position loops)Firing Unit (pulse generator)

Actuators (gate drives)Sensors

Analog sensors (current, voltage, torque)Pulsed ‘logical’ sensors (position and speed encoders)

Controller Plant

Power

Electronics

ConverterActuators

Sensors


Controller

PWM Firing

Example: AC Drive with NPC Multi-Level Inverter


Why Real-Time Simulation?

Simulation is a must, to address the challenges of modern electrical power drives and systems.

But why real-time?To interact with the simulated system To connect the simulated system to physical components in the real worldSimulation can be blended with physical hardware in every stage of the development process


Real Plant

Rapid Control Prototyping

RT-LAB Simulator

Power

Electronics

Converter

+ -

Controller

Testing a Rapidly Prototyped ControllerWith a real plant


Controller

Hardware-in-the-Loop testing

RT-LAB Simulator

+- Motor

Plant Model

Testing Real Controllerwith Real-Time Plant Model

This is Hardware in-the-loop (HIL)


PMSM drive controller


Testing PMSM drive controller with a RT Simulator

Real-TimeDigital Simulator


RT-LAB simulator of the PMSM drive

10µs80µs

80µs10ns

SimPowerSystems & ARTEMIS

Xilinx Virtex II Pro FPGA board@ 100 MHz

RT-Events Time-Stamped Bridge

16-bit D/A with DMA transfer

Shared Memory Communication

Multi-processor, multi-rate


PMSM drive simulator results

0 0.05 0.1 0.15 0.2-25

-20

-15

-10

-5

0

5

10

15

20

25

Time [sec]

Motor Current [A]

0 0.05 0.1 0.15 0.20

5

10

15

20

25

Time [sec]

Motor Torque [Nm]

0 0.05 0.1 0.15 0.2-25

-20

-15

-10

-5

0

5

10

15

20

25

Time [sec]

Motor Current [A]

0 0.05 0.1 0.15 0.20

5

10

15

20

25

Time [sec]

Motor Torque [Nm]

0 0.05 0.1 0.15 0.2-25

-20

-15

-10

-5

0

5

10

15

20

25

Time [sec]

Motor Current [A]

0 0.05 0.1 0.15 0.20

5

10

15

20

25

Time [sec]Motor Torque [Nm]

Off-line simulation:• SimPowerSystems• Native Simulink• Time step size 10 µs

Off-line simulation:• SimPowerSystems• Native Simulink• Time step size 1 µs

Real-time simulation:• RT-Events

Time Stamped Bridge• Time step size 10 µs


PMSM drive simulator: Effect of Freq & dead time

(a) Dead time = 0.7 µs

(b) Dead time = 4.2 µs

(c) Dead time = 9.8 µs

B. Motor current whenchanging dead time

(a) PWM freq. = 9000 Hz

(b) PWM freq. = 4500 Hz

(c) PWM freq. = 2250 Hz

A. Motor current whenchanging PWM frequency


Typical EES Simulator configuration:

• Single Xeon (top PC)• Dual Xeon (bottom PC)

• Analog I/O interface• Time Stamped Digital I/O

PC-based

RT-LAB Electric RT Simulator

real-time digital simulator

Uses Off-the-Shelf Pentium processorsDual or Quad Xeon configuration used for electrical simulators

Simulink-based real-time simulatorUltra-fast re-configurable FPGA card for I/OsQNX or RT-Linux real-time OSSample time below 10 us

Typical EES Simulator configuration

Ethernet

Targets

Host

ExternalHardware under test


RT-LA

B Electric Sim

ulator

HardwareTargets: PC-ClusterI/O: FPGA-basedRTOS : QNX or RT-Linux

Real-Time ParallelProcessing

RT-LAB Simulator & Model Preparation

RT-LAB Software

Solvers, Models

Simulink

User Application User Model

RT-EventsFiring & TSB ARTEMIS

Electric Circuit

SPS (PSB)

PC PC PC

External Equipment I/O I/O I/O


RT-LAB Specialized RT Simulation Toolboxes

ARTEMISRT-EVENTS

Real-time simulation of electrical systems (general cases) –Used with SPS

Voltage source inverters for motor drives (PMSM, IM, SRM, etc)

DC-DC converters

Firing Pulse Modeling

Internal combustion engine simulation

Events based systems

Real-time simulation of voltage source converters

Power networks (HVDC, SVC, etc..)

Thyristor drives

Cycloconverters,

Diode & thyristorsrectifiers

Typical applications

Use


ARTEMIS Blockset

Real-time solvers & techniques for the SimPowerSystemblockset for the simulation of electric circuitsMore stable and more precise with larger time steps

Realistic time steps (30-60 µs) enabling the use of commercial PC-based systems

Designed for RT:Constant computation timeStrictly-non-iterative integration, no algebraic loopsCompatible with the code generator

Real-time interpolation for precise simulation of power electronics (GTO, IGBT, etc)Support for parallel processing:

Reduction of matrices’ size and number by splitting the equations of separated systems


RT Interpolation with RT-Events™ Library for Simulink

Blocks propagate in-step switching information in addition to standard logic signalsIn-step timing information permits accurate simulationIncludes logic, integrators, comparator blocks


Discrete-Step Simulation of Pulse Signal causes Jitter

Sampling Period

Real (ideal) Pulse

Sampled Pulse

Errors

• Discrete-step simulation of an ideal pulse causes a varying error on the transition timings Jitter

• Jitter error increases with the sampling period

• Sampling period of the Digital Simulator cannot be small to match the resolution required (sub-µs) to generate or capture a pulse


Observing Jitter on the Oscilloscope

Correct pulse

Sampled pulse presents jitter

Sampling Period


How to Reduce the Errors Caused by the Jitter

Errors can be reduced by decreasing time step to a very low value often below 1 us, but this makes the real-time simulation not practical or simply impossibleChallenges

How to increase precision without excessive simulation time?How to make real-time control prototyping with precise simulation of firing pulse generation, encoders, etc?

Jitter

Inaccuracy

Non-Characteristic Harmonic

Steady-State Error


Real-Time Interpolation and RT-Events

If the pulse is generated by comparing two signals, such as SPWM pulse signals, interpolation must be used RT-Events comparator

Real-Time Interpolation

Ts

Signal 2

Signal 1

Time-Stamped Pulse

Time-Stamp Discrete Comparator Pulse (State)

Ideal Pulse

RT-Events Comparator


Pulse Generation with FPGA and RT-Events programmed in Simulink

Example: SPWM generation with RT-EventsTo generate PWM according to the theoretical comparison of a reference and a carrier, a comparator is neededProblem: The Simulink native discrete comparator cannot be used because it will give errors caused by fixed-step simulation at a step that is much higher than the resolution required. Note that this resolution is expected to be in the one µs range and lower, but even with today's fastest DSP or processor, the digital simulation time step cannot be that low; the time step cannot go lower than 10 to 50 µs.

SolutionTo use RT-Events comparator, because RT-Events has interpolation and has two outputs: the STATE of the pulse (0-1) and a time-stamp (time of occurrence of the transition within the previous time-step); and these two are normally connected directly to Event Generator block from the FPGA I/O library.

Automatic mapping of the Simulink Block diagram to the Hardware (Pentium & FPGA)

Simulink Model

PCI bus

Pentium processors

Simulator Hardware(processor & FPGA)

FPGA Board


Relation between RT-EVENTS & I/O event capture

Fully numericalevent-compensatedsimulation

Hardware-in-the-Loopevent-compensatedsimulation

Ex: Counter frequency: 100 MHzSample time: 50 usMax count= 50us *100e6=5000


Conclusions

Power electronics and drives with PWM frequency up to 10 kHz can be simulated in real-time using COTS technologies

Pentium and AMD processors, QNX and RT-LINUX OSFPGA based I/O

Standard RT tools are not enough for accurate simulation of power electronicsSimulink, RTW code generator and specialized toolboxesare used as the core simulation technologies for control prototyping and simulation of power electronics:

RT-Events Time-Stamped BridgesARTEMIS add-on to SimPowerSystems blockset for Simulink


DC-DC Converter

Introduction

Parameters:Source: 400 VLoad: 1 Ohm, 5 mHCarrier: 1010 Hz

RCP & HIL Simulation of Power Electronics

Typical Example

Challenges and Problems

Q&A Controller

Plant


DC-DC Converter

Introduction

RCP & HIL Simulation of Power Electronics

Typical Example

Challenges and Problems

Q&A

Documents

Real-Time Simulation of Electric Drives & Systems with RT … · RT-LAB Presentation Overview ... RT-LAB Simulator +-Motor Plant Model Testing Real Controller with Real-Time Plant