Back to Basics: The Fundamentals of Power

Figure 1: 45% of worldwide power
consumption fuels motors

Ask any number of engineers to define "power" and you'll get any number of answers, and none of them would necessarily be wrong. Sometimes it's just a matter of perspective.

Device Analysis in Switch-Mode Power Supplies

Figure 1: Setup for analysis of switching losses

in a switch-mode power supply's MOSFET

Our survey of testing switch-mode AC-DC power supplies started by looking at the variety of measurements one might make on these devices and why differential probes and amplifiers are often the best choice over passive probes. Subsequently, we examined the key sources of error in power-supply measurements and how to minimize them. Now it's time to start taking some measurements with an eye toward device analysis, particularly the switching transistor in a switch-mode supply.

Testing Challenges in Motor Drive Systems (Part III)

Figure 1: An example of PWM for

a single power semiconductor

As noted in an earlier post, variable-frequency motor drives (VFDs) display a good amount of variation in terms of architectures and topologies. Another differentiator between VFDs is their application of pulse-width modulation (PWM) techniques.

Testing Challenges in Motor Drive Systems (Part II)

Figure 1: This image depicts the complete design and
debug challenge posed by a variable-frequency motor drive

In our first post on motor drive systems, we broke down the major subsystems in a "generic" variable frequency drive (VFD) and discussed some of the test requirements in those subsystems (Figure 1). Next, let's have a look at some of the variations in real-world VFDs in terms of architectures and topologies.

Testing Challenges in Motor Drive Systems

Figure 1: The power section of a motor drive system requires
measurements of line input, PWM output, and efficiencies

Motors are everywhere in our world, and nowhere more so than in  our vehicles. For example, when's the last time you had to crank a car window up and down to pay a highway toll? Or, for that matter, when did you last manually adjust the seat position or rear-view mirror angles? These aspects of vehicles are all typically motorized these days.