Digital Power Control Enables System Identification

Focus:

In power supply designs with conventional analog control, if you want to measure the transfer characteristic of the control loop (system identification), you'll typically need to use as a network analyzer. However, in power supply designs with digital loop control, it's possible to measure the frequency response of the control loop without a network analyzer. Digital power controllers such as the Si8250 make it possible to inject and monitor test signals at various points in the control loop. Those measurements can then be used to obtain frequency response of all or part of the control loop using fourier transforms and other math functions. This article discusses the controller characteristics that enable system identification and techniques for achieving accurate results.

What you’ll learn:

• How to measure frequency response of a power supply control loop in real time without a network analyzer
• How to measure frequency response of a power supply control loop in digitally controlled power supplies
• How to understand the impact of digital power controller characteristics and test techniques on the measurement of control-loop frequency response

Notes:

Article appeared in PET's November 2006 supplement on Digital Control. In the same publication, also see "Digital Control Measures In-System Reponse."

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Author & Publication:

Brett Etter, Marketing Manager, and Ross Fosler, Senior Applications Engineer, Silicon Laboratories, Austin, TX, Power Electronics Technology, Nov 01 2006

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