Adaptive Minimum-On-Time Control for DC-DC Converter Efficiency
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Solution Overview
Problem
Existing DC-DC power converters face efficiency decreases due to fixed minimum on-time settings, which do not adapt to changes in input voltage, leading to increased switching losses as the input voltage decreases.
Innovation Solution
Implementing adaptive minimum-on-time control in DC-DC converters, where the duration of the minimum-on signal is adjusted based on measured input or output power magnitudes, using a controller and adaptive oscillator to generate PWM signals that synchronize with SET and RESET signals, thereby optimizing the duty cycle of the power switch.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a fixed minimum on-time is set based on maximum battery voltage, then the converter operates correctly at maximum voltage, but efficiency decreases over time as input voltage decreases
Solution Approach 1:
The patent implements adaptive minimum on-time control where the minimum on-time parameter dynamically adjusts based on the actual input voltage level. The controller monitors input voltage and modifies the minimum on-time accordingly, transitioning from a static fixed value to a dynamic adaptive value that optimizes efficiency across varying battery conditions.
Solution Approach 2:
The patent changes the minimum on-time parameter from a fixed value set at maximum voltage to a variable parameter that changes with input voltage. By establishing a relationship between input voltage and minimum on-time, the system adjusts this critical timing parameter to maintain optimal switching efficiency as voltage sags occur during battery discharge.
2Reliability
If the minimum on-time is increased to ensure proper operation at low voltage, then reliability improves, but switching losses increase
Solution Approach 1:
The system dynamically adjusts minimum on-time based on real-time voltage conditions rather than using a conservative fixed high value. This dynamic adaptation allows the converter to maintain stability when needed while avoiding excessive on-time that would increase switching losses during normal operation.
Solution Approach 2:
The minimum on-time parameter is changed from a static high-value setting to a voltage-dependent variable parameter. The controller modifies this parameter according to the input voltage level, ensuring adequate on-time for reliability at low voltage while minimizing on-time at higher voltages to reduce switching losses.
3Device complexity
If the duty cycle is fixed, then the control logic is simple, but the converter cannot adapt to changing input voltage conditions
Solution Approach 1:
The patent implements feedback control where the controller monitors input voltage conditions and uses this information to adjust the minimum on-time parameter. This closed-loop feedback mechanism enables the converter to automatically adapt to changing voltage conditions while maintaining relatively simple control logic through systematic voltage-to-timing relationships.
Solution Approach 2:
The converter performs self-adjustment by automatically modifying its minimum on-time parameter based on sensed input voltage conditions. The system serves itself by detecting voltage changes and autonomously optimizing its timing parameters without external intervention, balancing adaptability with control simplicity.
Data Source
AI summary
A power converter includes a power switch adapted to receive an input power from an external power source and to generate an output power, and an adaptive oscillator adapted to output an adaptive minimum-on signal of the power switch in response to a change in measured magnitude of at least one of the input power and the output power.