has a Doktor Ingenieur degree in Electrical
Engineering. He has worked for 25 years in power electronics doing
research, teaching, and in industrial applications. Dr. Rodriguez
has more than 100 publications in the power-electronics field. He
is currently professor and head of the Department of Electronics at
the Universidad Técnica Federico Santa María.
electrical engineer and graduate student at the Department of
Electronics at Universidad Técnica Federico Santa
is a graduate
student at Universidad Técnica Federico Santa
Modern power-electronic systems exhibit a
strong interaction between voltage sources, loads, power
semiconductors, and control circuits. This element interaction is
complex, due to the nonlinear behavior of the power semiconductors
and the different magnitudes of the circuit's time constants. Due to this complex interaction, simulation is
almost the only way to study the behavior of power-electronic
systems prior to prototyping.
Several simulators, each with different capabilities, are
available. We assessed four types of commercial simulation programs
designed to simulate power electronic systems on a single-phase
boost rectifier circuit:
- Equation solver: Matlab: Simulink Version 5.3.0
- Circuit-equation solver: Matlab: Power System Blockset Version
- General circuit solver: PSpice (Microsim 8)
- Power-electronics-specific circuit solver: Simplorer 4.2
The Boost Rectifier
Simulation of a single-phase,
was performed to compare the four programs. This
circuit has several features that are commonly found in modern
- A fast current-control loop that can be implemented with a
Bang-Bang controller or a proportional-integrative (PI) controller
plus pulse-width-modulation (PWM) modulator.
- A slow DC voltage-control loop.
- Use of fast-switching power semiconductors.
The purpose of the boost rectifier is to generate a controlled
DC voltage (vo) and a sinusoidal input current
Figure 1: Boost-rectifier power circuit (a)
and control system (b).
These tasks are done by changing the conduction state of
transistor T1, which operates in the switching mode (on/off). When
T1 is on, the single-phase power supply is short-circuited through
inductance L, increasing current IL. When T1 is off, the
inductor current flows through diode D, charging capacitor C. In
this case, the inductor current decreases due the output voltage
(vo). This voltage should be at least 10% higher than
the peak value of the source voltage (vs) in order to
assure good control of the current.
The equations describing this rectifier are:
Figure 1b shows the control system of the rectifier, which
includes a PI controller to regulate the output DC voltage. The
reference value ILref for the inner control loop is the
product of the output of the PI controller and the normalized
voltage vf. A hysteresis controller provides a fast
control for inductor current IL.
Click on the links
below to view the simulators' performance results:
Matlab Simulink Matlab PSB Pspice Simplorer
Simulation Conditions and Results
||220 V, 50 Hz
Table 2: Circuit values used
in simulating the single-phase boost-rectifier power
The simulation with Matlab-Simulink was performed with a
fixed-step algorithm to avoid convergence problems. In PSpice, the
voltage tolerance (VNtol) was 10-6, while the maximum
number of iterations used in Simplorer was 20.
||1.5 x 10-3
|Max. Step Size
|Min. Step Size
* Other algorithms are available, but this one is
Table 3: Simulation
conditions for the single-phase boost-rectifier power
All the simulators in this comparison generated the same
results, shown in Figures 5 and 6. Figure 5 shows the dynamic
behavior of the output voltage vo and inductance current
IL in response to step-changes in the load (from 100
to 50 and back to 100 ). Table 4 shows the time needed to simulate
the rectifier during this operation. Figure 6 presents the
steady-state behavior of input voltage and current.
Figure 5: Dynamic behavior of inductor current
(IL) and output voltage (vo) due to changes
in load resistance.
Figure 6: Steady-state behavior of input voltage
(vs) and input current (Is).
Table 4: A comparison of the four simulators shows
substantial differences in run times, difficulty of use, and
control-element availability. All simulations were done on a
Pentium III 500 MHz computer with 64 Mbytes of memory. *
Does not include display time.
Matlab-Simulink is clearly the fastest
simulator. Although Simulink and PSB use the same simulation
environment, they show the largest execution time difference.
However, with Matlab-Simulink the execution time does not take into
account the initial setup time required to obtain the equations and
corresponding block-diagram representation.
The Matlab environment is well known for its very powerful
control tools. Simplorer can use these tools through the Sim2Sim
module to increase its control librarythis capability lets
Simplorer implement the standard controllers used in power
electronics. Finally, PSpice's control features are limited and are
more difficult to implement, making PSpice a poor simulation
alternative. Table 4 shows that Matlab-Simulink is the most
difficult to use, while Simplorer is the simplest.
Given the previously stated particularities of power-electronic
systems and considering the results of this work, the authors
conclude that a power-electronics-specific circuit simulator offers
the most convenience. This type of program simulates the power and
control parts of the circuit very well. In addition, these types of
simulators have low execution times, are numerical robust, and are