Realising the Full Potential of Digital Control Requires Continued Software Innovation

August 31, 2016 // By EDN Europe
By Martin Hägerdal, Head of Ericsson Power Modules, Ericsson Power Modules
As they evolve to keep up with the world’s reliance on internet connected devices and the Internet of Things, telecoms infrastructure systems are rapidly increasing in density and complexity

The technical requirements on the systems that power them are also becoming increasingly stringent. Modern telecoms systems mix high speed data transfer with multiple sensitive loads, may include many tens of different power rails (some with very high currents), and pack it all in to a very tiny space. Some even retain an element of flexibility by including FPGAs or processors, which have changing power requirements when reprogrammed.

To meet these challenging requirements, DC-DC converter manufacturers have embraced digital control, which enables sophisticated power management functions. Digital point of load modules are increasingly able to adapt to changing operating conditions in real time; control loop parameters can be adjusted to compensate for component aging, intermediate bus voltages can be varied dynamically to respond to low loads, and clock frequencies can be reduced according to demand to save power. 

However, implementation of all these complex functions depends on advanced software which works in parallel with the latest hardware to ensure efficient operation at all times. At the design stage, the software analyses the power needs of the system and the potential for variation in the load, then models the power supply’s most efficient response to these conditions. Assuming the model is accurate, the implementation of the module plus its filters can then be optimised. Without this software, it would be impossible for the hardware to reach its full potential in terms of energy savings, cost effectiveness and user friendliness. Continued software innovation is therefore crucial to complement and support hardware innovations that the industry develops to meet the increasingly stringent needs of data centres.

Ericsson Power Designer (EPD) is a great example of an advanced software program that complements flexible digital power hardware. This design tool is used to configure, implement and monitor power conversion systems, enabling techniques such as adaptive compensation of the PWM control loop and other advanced energy optimisation algorithms on Ericsson Power Modules ’ PoL modules such as the BMR466.

Also, if several BMR466s, for example, are used in one system, selecting the Phase Spreading function in the Ericsson Power Designer reduces input ripple current and capacitance per product.. The EPD estimates the amount of input ripple current, and capacitor selection can be made based on this number .

Power system designers can also use the Ericsson Power Designer software to stabilise the power supply with respect to fast transient performance over the range of expected operating conditions. This is particularly beneficial when the PoL converter is supplying power to an IC whose current requirements change quickly; maintaining a voltage within the IC’s limits while this happens can be extremely difficult.

Ericsson Power Designer allows the control loop to be optimised automatically using built-in mathematical techniques

Transient response can be optimised in the software by simulating an output filter; component values can be adjusted (right down to the capacitors’ ESR) as well system parameters such as the size of the load step and the parasitic inductance in the board, until the best solution is found. Ericsson Power Designer uses mathematical methods to solve this problem for the designer, who