Animation of Power Electronics and Electrical Drives.

During simulation you can see the current flow in the circuit and the level of the node-voltages, the level of the branch currents and most important, he can see the current path in the circuit. The simulation tool can animate any power electronic circuit or electrical drive.

Visualizing simulation results.

The early simulation programs produced a long list with numerical results. Nowadays most simulation programs offer the presentation of simulation results in graphical windows. The user has the ability to examine these graphical results by using a mouse, to obtain the numerical value at each point in time.

The next step is the visualization of the simulation. Most important in power electronics is the current-path. For example, freewheeling of diodes becomes clear, when the user sees the current-path changing from switches to freewheeling diodes.

The following visualization guidelines are used:

• The intensity of the voltage, current or signal is given by the color, which varies from black to red, as defined by a rainbow of colors.
• The color of a node in the electric circuit is dependent on the voltage level of that node.
• The color of an electric circuit component is dependent on the level of the current through that component.
• The color of an electric circuit wire is dependent on the level of the current through that wire.
• The color of a wire in the block-diagram is dependent on the level of the signal on that wire.
• Certain components animate depending on an event, taking place in the component, such as opening or closing of switches.

Importance of animation.

Animation of electric circuit may look like a toy. This is however absolutely wrong. Animation is a viable tool for teaching, gaining insight, checking the behavior, or searching for failure modes.

The advantages for teaching are clear. Students, for example, can see the current-paths in rectifiers or understand the freewheeling and discontinuous mode in SMPS.

For complex topologies, such as the Vienna-Rectifier [Kolar, 1994], animation can be very helpful to understand and verify the principle of the converter. During animation, it becomes clear to the user how the converter is behaving.

During animation, failure modes are detected. Even those failure modes, the user was not aware of. During failure analysis without animation it requires a lot of time to check each component. With animation, each failure is directly displayed, for example a switch is opened or closed at a wrong interval. Or some voltage levels are too high.

Practical implementation.

Animation costs time. A simulation should be as fast as possible. Animation slows down the simulation. Therefore the user should have the ability to turn the animation on or off.

If a circuit is animated, the simulation in most cases has to be slowed down, in order to follow the behavior of the system. Therefore the time-consumption of animation is in many cases not a problem.

In order to speed up the animation it is not always necessary to show each simulation step. For example, if a small time step is required for the simulation but the animation is slow varying, compared to the time step, not each time step has to be displayed. This can be achieved by not displaying each time step in the animation. Figure 2 shows a typical dialog box for animation properties.

Figure 2: Animation properties.

To visualize the values of voltage and current, two different levels are required. For example a SMPS operating at the AC-mains can have current levels of only up to 1 Ampere. Also the control signals can vary in value from the voltage and current level. Typical control signals can range between 0 and 1, where the on-status of a control signal is clearly signaled by a red color and the off-status is signaled by a black color.

To prevent that the schematic starts blinking like a Christmas tree, the user should have the possibility to turn on or off various animation effects. For example, the constant display of numerical values at each node can make the schematic very crowded and therefore the user should have the possibility to turn it off.

Example Vienna-Rectifier

In figure 3 the Vienna-Rectifier [Kolar, 1994] is displayed. The current-path, which is colored during the animation, is shown thick in this figure. One can see clearly that the complexity of the current-path gives valuable information on the functioning of the converter.

Figure 3: Current-path in the Vienna-Rectifier.

Example Buck converter

In figure 4 the animation of a buck converter is shown. In the figure the freewheeling of the diode is shown. The level of the output voltage and the level of the current through the inductance L1 is displayed by two analog meters, which during the animation show the actual value.

Figure 4: Buck converter with analog meters.

Example DC shunt machine with crane

In figure 5 the animation of a DC shunt machine with crane is shown. The DC shunt machine is controlled by a controlled voltage source, which is regulated by a library-block 'Crane Control'. Also a controlled rectifier could have been used here. The library-block modeling the crane includes an object-block, which models the visualization of the crane. Depending on the angle of the axis of the DC shunt machine, the load is lifted by the crane.

Figure 5: DC shunt machine with crane.

Conclusions

Animation gives valuable information about the simulation of Power Electronics and Electrical Drives. Displaying current-paths gives insight in the behavior of the circuit and can reveal failure modes. It reveals more insight in the circuit operation then only displaying simulation results in graphs. If animation is based on simulation, also complex circuits can be animated. This makes animation a practical tool for designing power electronics and electrical drives.