Design Con 2015

Integrating power electronics design technologies

Tony Christian -October 04, 2012

The field of power electronics, the application of electronics for the control and conversion of electric power, is underpinned by basic electrical principles that were established in the distant past by the pioneers of electrical science. But today, the need to supply, modify and control the voltage, current or frequency of electric power arises in a vast number of applications and products spanning a huge range in terms of power handling capability.

The industry has generated numerous technological advances to address the ever-growing spectrum of requirements; in its 30th anniversary edition, Power Electronics Technology described some of the most important developments of the past three decades.

Figure 1:  A computer power supply can serve a variety of applications

In the limit, the requirements for power electronics systems range from those designed to handle a few milliwatts such as the DC/DC converters designed to maintain constant voltage as the battery power declines in mobile phones and portable hand held devices, to those handling many megawatts in the large power converters used in the electrical generation and distribution industry.

Naturally, the challenges for power electronics designers vary considerably according to application and scale. Those challenges now cover not only electrical function (particularly the drive to maximize efficiency for the power and frequency range in question), but a host of practical and, especially in consumer products, even aesthetic design constraints. For example, the developers of devices like mobile phones or PCs seek to pack ever more functionality into smaller spaces and their power supplies must not consume a disproportionate amount of that space.

At the same time, the ever-closer proximity of the components imposes increasing constraints on electromagnetic radiation and limits the ability to dissipate heat. But that kind of challenge is not limited to what is usually regarded as the high tech sector – it seems that even purchasers of auto battery chargers want them to be small and attractive!

 

Figure 2: High-voltage electric generation and distribution requires significant power.

For applications of larger scale involving supplying power to electromechanical devices, the design of the power electronics must take into account and adapt to the behaviour of the load (usually a motor or drive system) across its operating range. Considerations will include factors such as power factor optimization and minimizing losses, dealing with harmonic currents and eliminating any electromagnetic torque oscillation that might give rise to electromechanical vibrations. 

In many applications, including at the high end the power generation and distribution industry, achieving the electrical functionality often requires the design effort to extend to customizing the characteristics of individual system components. There is then the challenge of balancing optimization of the performance of individual elements with the behaviour of the overall system.


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