Predictive DC-DC Controller for Voltage Overshoot Mitigation
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Solution Overview
Problem
Inductive DC-DC converters face challenges in managing load changes, leading to potential damage due to voltage overshoot and undershoot, especially in advanced CMOS technologies, as existing control methods are limited by physical constraints and require large capacitance or time-optimized control schemes.
Innovation Solution
A predictive controller for inductive DC-DC converters that generates multiple switching phases based on a predetermined load profile, allowing for anticipatory adjustment of inductor current to minimize voltage deviations by short-circuiting the inductor during specific phases and optimizing switching phase durations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If time-optimized control (TOC) methods are used to minimize voltage overshoot, then voltage regulation improves, but response time increases due to physical limitations of inductive energy transfer
Solution Approach 1:
The supervisory controller predicts future load changes based on a predetermined load profile and adjusts the inductor current reference value in advance before the actual load transition occurs. This preliminary action allows the DC-DC converter to proactively compensate for upcoming load changes, minimizing voltage overshoot and undershoot while maintaining fast response time.
2Reliability
If output capacitance is increased to minimize voltage overshoot, then voltage regulation improves, but device complexity and cost increase
Solution Approach 1:
The supervisory controller continuously monitors the actual load current and compares it with the predetermined load profile to detect transients. Based on this feedback, the controller dynamically adjusts the inductor current reference value to compensate for load changes, achieving effective voltage regulation without requiring large output capacitance.
3Loss of time
If switching frequency is increased to improve dynamic response, then response time decreases, but power losses increase
Solution Approach 1:
The controller dynamically adjusts the inductor current reference value based on predicted load changes rather than operating at fixed high switching frequencies. This dynamic adaptation allows the system to achieve fast response when needed while operating efficiently at lower frequencies during steady-state conditions, reducing overall power losses.
Data Source
AI summary
A predictive controller for an inductive DC-DC converter comprising a switchable inductor is described. The predictive controller includes a DC-DC controller configured to generate a plurality of switching phases to control the inductor current in the switchable inductor, the duration of the switching phases being determined from at least one of a reference inductor current value and a reference output voltage value. The predictive controller includes a supervisory controller coupled to the DC-DC controller and configured to set a reference inductor current value dependent on an expected change in load current and/or voltage of a load configured to be connected to the load terminal. The expected change in load current and/or voltage is determined from a predetermined load profile.