Advanced Research Projects

Transient Reduction of dc-dc-Converters via Augmentation and Geometric Control

Grant Pitel with adviser Philip T. Krein

Fast dc-dc dynamic performance is crucial for supplying clean power to dynamic loads. This is a particular concern in low-voltage digital systems in which fast, high-current load steps can lead to significant transients. Two approaches are being evaluated that allow converters to reject disturbances without sacrificing bandwidth—counteracting goals.

The first approach is through control. Controls that utilize prior knowledge or that can identify converter parameters can improve transient performance. When compared to traditional control techniques, this improvement was limited to about an order of magnitude. The second approach is to add to the load alternative conduction paths that overcome system bottlenecks, as shown in Figure 37. The augmentation may increase control complexity, but the experimental results in Figure 38 demonstrate transient performance that has improved by many orders of magnitude. The proposed approach creates a converter that more quickly rejects disturbances and becomes an alternative to the present trend of increasing the size and number of energy storage elements.

Figure 38 Voltage output from reference step, 1 to50 Ω, and 50 to 1 Ω load steps.