29. Januar 2021, 10:05 Uhr | Ute Häußler
Technologies are developing rapidly, parameters are changing. The development process for power engineers must also adapt to new circumstances. But what are the decisive criteria in 2021 and what should power supply developers pay particular attention to?
The applications for developers in power supply differ greatly, the practical application makes the difference. Whether it's a DIN rail power supply or a PoL converter on a microcontroller has a major impact on the power criteria that engineers have to consider in their everyday work. As different as the design and structure of the practical application may be, cross-application "pain points" are similar in many power supply projects. From our dialogue with five power managers, we have filtered the 5 most critical points that power designers should pay attention to in order to get the most out of their respective applications in 2021.
»The power supply of the future is designed for plug-and-play,« says Frank Cubasch, Managing Director at Magic Power. Both in use and already during development, a modular structure with ready-made components helps to keep the design process short and to customize the power supply.
Of course, depending on the price-performance ratio, power developers will try to extract the best possible performance for »their application« at the time of design. But in addition to the current peak performance and good efficiency, according to Frank Cubasch of Magic Power especially at lower load and size, scalability is a main criterion today: for a quick upgrade to more power and less time-to-market for future generations. The modular structure of the power designs, which can be re-equipped with components of the next higher performance class if required, ensures less development effort. Many manufacturers offer entire component families that make such a changeover comparatively easy. Philip Lolies from STMicroelectronics puts it in a nutshell: »Enable an increase in performance« - without a complete new development.
With smaller designs and higher packing density, the operating temperature range increases to 150° C to 175° C in some applications. This is associated with an "increased variance in device parameters," according to Vishay's Olaf Lüthje. He says these include temperature coefficients of resistors, long-term drift, reliability (MTBF), volume efficiency or power density, and also the associated stress to which solder joints are subjected. Frank Cubasch of Magic Power also urges power designers to pay attention to a flat derating curve - that is, the maximum allowable power dissipation of the electrical component as a function of ambient temperature. Aly Mashaly of Rohm refers to the "thermal design of discrete SMD components and power modules" as a criterion, while Philip Lolies of STM says simply that new generations of semiconductors should be chosen without compromising thermal performance when selecting components.
Practical tip: Select power inductors which have been continuously developed for higher temperatures and higher currents with the same size or correspondingly for the same performance with a smaller size.
There are two basic paths for power developers to follow in their application design: Higher power density or increasing switching frequency. Aly Mashaly of Rohm Semiconductor advises that when increasing switching frequency and using wide band gap (WBG) power semiconductors, the primary consideration is the interaction of the WBG devices and passive components. IGBTs or MOSFETs based on SiC or GaN can significantly reduce the cost of passive components. The challenge of this development approach for power designers is to operate the WBG components in such a way that the optimum operating conditions can be set at any time and active modulation is possible.
According to Mashaly, attention should also be paid to a low-inductance design of the circuit: With fast-switching components, the resulting parasitic inductances and their influence on the switching behavior must be taken into account. Steeper switching edges increase the influence of feedback, high leakage inductances contribute additionally. Low-inductance structures reduce the contribution to feedback caused by leakage inductances and do not increase switching losses.
Smaller designs in less space as well as higher switching frequencies are a challenge for the electromagnetic compatibility (EMC) of the overall system. It's not just new packaging concepts that must accommodate improved performance. Frank Cubasch of Magic Power and Rohm's Aly Mashaly point out in unison that a coherent and, in particular, application-specific EMC concept should already be developed during the design phase - and put through its paces before implementation begins. This keeps unwanted surprises to a minimum and allows designers to work on optimization during testing - without having to restart the design due to serious electromagnetic interference.
"Nothing ventured, nothing gained." In addition to leading-edge technology, Steve Lambouses of Texas Instruments focuses on an innovative approach to setting up the design. In his opinion, developers working toward leaps and bounds in performance must abandon old ways of thinking and embrace newer, disruptive technologies. Ultimately, Lambouses says, those who are open to new technologies will be successful. He therefore advises power developers to "Be an early adopter!".
However, the Dallas-based VP High Voltage Power also says:»The time for dabbling is definitely over for power supply developers. There are proven turnkey solutions on the market that can give designers an effective jump-start on production designs. As the world continues to evolve at an ever-increasing pace, power designers need to be smart and take advantage of all available help.«
This is especially true in increasingly complex technological designs. Anyone who wants to build a drone may know about its control mechanisms, but not everyone is »a born power designer,« according to Lambouses. He believes the industry needs to contribute tools, training and support to advance the evolution of power electronics. At best, with modular components that require less dedicated expertise to implement.
Philip Lolies works as VP Marketing Analog / Sensor / Power at STMicroelectronics.
Corona made it clear last year, the automotive industry has just had to bridge its semiconductor shortage with short-time work: Supply chain is an indispensable part of any design planning. Under these conditions, STM's Philip Lolies warns to pay particular attention to a »robust and resilient supply chain,« with good »manufacturing flexibility through the right mix of in-house and third-party manufacturing.«