The message type: warning or error.
Description: brief error description
Fix: the way to solve the problem.
- click this icon to view the detailed information about this error and suggestions on how to fix it.
During optimization PI Expert automatically chooses all components required for the power supply being designed. Once PI Expert receives the input and output specifications, the optimization process iterates on multiple parameters and produces several results. It then ranks these results and presents the top solutions based on the specifications provided.
The Design Defaults tab of the Tools | Preferences menu allows you to specify how to optimize the new design and to show the preliminary optimization results. You can set the number of optimized solutions to be shown in the Show Solutions Filter dialog box as well. You can turn on the display of the Show Solutions Filter dialog box for designs in the Default design form.
The following types of optimization are available from the Design Options design form:
Cost.
Efficiency (not available for LinkSwitch-XT, LinkSwitch-PL, TinySwitch-II, TinySwitch-III and TinySwitch-4 device families).
Use the Active Design | Start Optimization menu to run the optimization process for the active design using any relevant user inputs. Selecting the Active Design | Auto Design menu will override all user entered parameters and changes for the active design and start optimization. The optimization engine gives you the flexibility in choosing the design components and obtaining the desired result.
Cost optimization runs on the following key concepts:
The smallest PI device that is capable of delivering the power is chosen first.
This step is not simply a check to ensure that the device’s rated power, taken from the data sheet, is greater than the power specified. This first step in optimization takes into the account a number of key operating parameters, which include the maximum duty cycle (DMAX), the peak primary current (IP), the reflected output voltage (VOR), and the peak to ripple primary current ratio (KP).
The smallest transformer core that is capable of delivering the power is then chosen.
Similar to the selection of the proper PI device, the selection of the transformer core is made using a number of key operating parameters. Some of these parameters include flux density (BM and BP), gap length (LG), primary layers (L) and the physical dimensions of the windings within the bobbin window fit factor (FF).
During the cost optimization process a number of designs using different combinations of cores, secondary turns, secondary output stacking configuration and output diodes are scored based upon criteria internal to the software. A list of the top scoring designs is maintained throughout the optimization process. Upon successful completion, the list of top designs is displayed. You can then choose the design which you believe to be the most appropriate for your application.
Efficiency optimization is available for the TOPSwitch and DPA-Switch family of devices only. There are two key factors that are crucial to understanding the efficiency optimization method:
The PI device capable of delivering the specified power with margin to the device’s current limit is chosen.
The PI Expert efficiency optimization routine will first find the smallest PI device capable of delivering the power specified. The software will then reduce the peak to ripple primary current ratio (KP) in an attempt to make the design more continuous. This decreases the peak primary current (IP) which will decrease the peak and RMS currents in both primary and secondary windings. This reduction in current magnitudes increases the overall supply efficiency due to reduced conduction losses.
The core capable of delivering the specified power efficiently is then chosen.
This step in the optimization routine ensures that the core selected can not only deliver the power but can also do so without significant losses. The losses accounted for are core losses as indicated by flux density (BM), copper losses as indicated by primary layers (L) and primary RMS currents (KP) in addition to leakage inductance indicated by gap length (LG).
As in cost optimization a number of designs are then examined and passed on to the optimization process. PI Expert then retrieves a list of the best scoring designs and then displays it.
PI Expert gives you the optimization status at the bottom of the main window. There are several possible optimization results:
Design Passed (Optimization Done) means that the software was able to successfully optimize the design according to your specifications without any warnings or errors.
Design Passed (No Optimization) means that there are no warnings or errors, but the design is not optimal. For example, the turns ratio may not be optimal, but no errors or warnings were received.
Design Warning (Optimization Done) means that the design has been successfully optimized, but there are one or more warnings issued.
Design Failed (No Optimization) means that the optimization was not able to meet your specifications and there are one or more errors or warnings.
If any problems or inconsistencies are found, PI Expert presents the list of warnings or errors at the bottom of the results window. Each line contains the following information:
The message type: warning or error.
Description: brief error description
Fix: the way to solve the problem.
- click this icon to view the detailed information about this error and suggestions on how to fix it.
For more information on the optimization errors and warnings see the Error List help topic provided in the PI Expert Suite help manual.