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Case Studies
Digital Power Management and Power Control, and its Impact on the Industry
Digital Power Management and Power Control, and its Impact on the Industry
Randy Malik
Senior Technical Staff Member
IBM
The following paper was presented at last year's Digital Power Forum (DPF). Information on DPF 2008 can be found at : http:/www.digitalpower.darnell.com
Abstract:
A power supply is no longer a power supply but a system by itself. It has to interact with the system and based on instructions from the system has to sequence and ramp POLs for proper functioning of the system. The power system has to interact with the main system in real time and configure itself based on the line and load requirements. Even a smallest toy uses some form of digital technology in conjunction with some sort of firmware. Any analogue function can be synthesized by digital technology. Even though the benefits of migrating to digital technology are huge, the power industry is still lagging behind the rest of the industry. There is a great need of communication between the main system and the power system for energy efficiency reasons. Depending on the environment, and line and load conditions, a power system has to be configured in various modes to respond to changing conditions. The benefits of going digital are huge including overall cost savings, but the fact remains - a change is always resisted until a time the customer desires functions which can not be accomplished by the old technology, for example Digital photography. As long as the old technology can perform the same functions that the old technology can, the old technology will continue to be used in one form or another. The transition point comes when the cost crossover point is reached and the new technology offers more for less.
The paper shows by illustrative examples why the digital technology is ready for prime time for power systems such as used for communication and data processing equipment used in data centers where there is a need of an integrated solution from micro to macro level and an interaction between systems is a must. In such systems the digital power technology is the right choice.
Digital Power
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Digital Control consists of controlling the response and load line of a power supply under different line and load conditions by means of a digital filter. The response time can be changed without any hardware by just changing the coefficients in a digital filter. This feature allows a common building block for different power systems to be used in different applications. It is almost impossible to have such a common building block by using analog control. Also analogue control is generally linear in nature but in applications such as motors and power factor correction, a nonlinear control is preferred.
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Digital Power Management: This consists of managing a power supply in real time by changing the firmware code. Examples include configuring the output voltage of a switcher, changing the mode of operation, changing the delay times, changing the speed of moving devices based on a particular software algorithm or communicating various errors or faults to the system, and change the behavior of the power system based on commands from the main system.
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