Designing efficient energy systems

Tom Colella, Electrocube


A top five list of the most common mistakes

We thought it would be helpful to assemble a top five list of the most common mistakes or “don’ts” that occur during the design of efficient power systems – and how to avoid them. This information comes from our observations and yes, some of our own experiences during Electrocube’s 50-plus years in the electronics industry. We hope it assists you in better meeting your customers’ expectations and design project requirements.

Mistake #1: Don’t challenge assumptions

Assumptions must be made to begin the design of any product or component in a system. Often, these assumptions are based upon accepted common knowledge or specific expertise and are usually proven to be correct. However, to avoid design flaws and issues, it’s important not to rely exclusively on assumptions. Instead, go deeper and account for the possibility that anything that can go wrong in the system will, in fact, go wrong. This scenario forces engineers to re-imagine a design that has the ability to function through every foreseeable challenge. It’s true that a designer can only foresee so much. Early in a project, verify the validity of assumptions with a specialist in that specific area of design and ask if s/he can point to any other possible problems that might arise.

If designers are looking at multiple solutions, it’s important for them to push to imagine and find as many complications as possible. For example, engineers building a 300,000-volt line parallel to a lower voltage line or other conductor may not foresee the problem of inductive coupling. But foresight about the potential problem may allow for grounding or another solution in the early design phase of the project.

As a group, engineers often think that others expect them to know it all and even pride themselves on their vast technical knowledge. Avoid a common trap. Acknowledge when a little assistance is needed to validate assumptions and imagine possible unforeseen complications that might arise. Doing so can ensure the likelihood of a smoother project.

Mistake #2: Quickly lock down design

We all like to be creative, innovative and recognized for our ideas. However, avoid getting so locked into a design that fulfillment of the original concept takes precedent over successfully meeting the customer requirements. Most customers want the smallest physical component possible yet still need room for modifications due to situational changes or new information. When creating the component, stay aware of new needs as they arise (see Figure 1). As the project evolves, it may be necessary to double- and triple-check with the client to ensure understanding of how the component affects (and is affected by) the whole system. If necessary, push for the disclosure of essential, previously undisclosed information.

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Figure 1: Work with component suppliers early in the design process to assure awareness of the latest available specifications and technology.

Don’t be so fixed on a design that you ignore other potentials that may come into play. Many unexpected scenarios can affect what is thought of as a simple design. For example, if a power grid is struck by lightening, the power grid spikes due to the surge in energy. This can affect alternative power sources that aren’t even on the grid, as can the interaction of ungrounded conductors in close proximity to other high voltage power sources. Don’t be afraid to ask (and re-ask) your client if there are any more facts or information to consider. If discoveries occur, be willing to change the design to adapt. Recognize it early and adapt quickly. Sometimes, a little design tweaking can result in an exponentially better product (see Figure 2).

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Figure 2: Don’t be so fixed on a design that you ignore other potentials that may come into play.

Mistake #3: Cut costs at the cost of almost everything else

Design engineers are under pressure to control or cut costs. We strive for efficient and cost-effective designs, but the lowest cost is not always the best choice. There’s a fine balance between reducing costs and preserving the critical safety margin and quality threshold. Falling to the temptation to cut beyond the point of good design practices is a mistake. The expression, Penny wise and pound foolish, comes to mind.

Many clients nearly finish their device design by the time they get around to the electro-magnetic interference filters or caps. Often, they’ve spent most of their project budget and used most of the available physical space. When physical space becomes an issue, a makeshift device can result. This is not ideal. It’s best to incorporate all aspects of design as early as possible so that options of quality versus cost can be weighed and carefully considered.

Open communication and collaboration helps to fuel experts doing their jobs well. Put them all on the same page – and the same phone call. Design engineers aren’t known for phone conversations, but when they are out of the communication loop problems can result. If going through a purchasing agent, push for direct communication with the design engineers as well. That way, nothing gets lost in translation. This saves time, reduces mistakes, and ultimately saves money.

Mistake #4: Decentralize project management

Today, design projects are fast-tracked tasks overlapped to shorten the project completion time. Under fast-track conditions, mistakes or errors, if not identified and corrected immediately, can spiral out of control in a matter of hours, jeopardizing the entire project. The usual protocol of reporting by exception during the next scheduled project meeting is often too little too late.

To avoid this problem, once an open line of communication is established, keep all the players in the room. Have conference calls as needed that include the project manager, other key team members, and the purchasing agent. Ask everyone to lay his/her cards on the table and share information that will ensure the success of the project. Bottlenecks can be dangerous, hold up design, limit knowledge and create design pitfalls. Encourage all parties to share information regularly for the good of the project.

Proper fast-track project management includes a system to mandate immediate and centralized reporting of all milestones reached and problems encountered. The window of opportunity to fix a problem before it creates other, more severe problems is very small. Only steady monitoring by the project manager and clear communication can avoid disaster.

Mistake #5: Skip consulting with the manufacturer’s technical staff

All too common a mistake is choosing a component without consulting the manufacturer’s technical staff – or moving forward with partial performance specifications only to find out later that they won’t work as assumed.

Consult with the manufacturer’s technical staff early in the project. Engineers have an implicit knowledge of the components they manufacture. Late entrance into the design process of a standard component takes deep questioning on the part of manufacturing staff to reveal potential issues – such as when the system design or its environment creates a previously unexpected variable – that needs to be addressed.

A component’s capability, size, temperature tolerance and/or reliability may often be incomplete or overlooked. Working with the component suppliers early in the design process can assure awareness of the latest available specifications and technology, as well as the best component choice available for the application. The help is free. Why not use it early and often?