Switched-mode power supply efficiency optimization via dynamic dead time control
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Solution Overview
Problem
Switched-mode power supplies face efficiency limitations due to long dead times, especially at low input voltages and loads, and struggle with maintaining high long-term stability and control quality across a wide range of input voltages and loads.
Innovation Solution
A switched-mode power supply design that includes a control unit using pulse width modulation signals with variable frequency and duty cycle to optimize efficiency, featuring a digital signal processor for monitoring and controlling controllable switches, and a dual control loop system to manage dead times and temperature effects, ensuring optimal operation across varying conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If long dead times are used to avoid shoot through, then reliability is improved, but efficiency deteriorates
Solution Approach 1:
The patent applies dynamics by making the dead time variable rather than fixed. The control unit dynamically adjusts the dead time duration based on real-time operating conditions including temperature, load variation, and component aging. This allows the system to use minimal dead time under stable conditions (improving efficiency) while extending dead time when safety margins require it (maintaining reliability).
Solution Approach 2:
The patent implements feedback mechanisms where the control unit continuously monitors operating parameters and adjusts dead time accordingly. Temperature sensors, load detectors, and component performance monitors provide feedback loops that enable the system to optimize dead time settings, reducing unnecessary energy loss while maintaining adequate protection against shoot through conditions.
2Device complexity
If fixed switching frequency is used, then device complexity is reduced, but efficiency deteriorates at low input voltages and loads
Solution Approach 1:
The patent transitions from fixed to dynamic switching frequency control. The control unit varies the switching frequency based on input voltage levels and load conditions. At low input voltages and light loads, the system adjusts frequency to optimize efficiency, while maintaining adequate performance across the full operating range. This dynamic approach resolves the contradiction by adapting frequency to conditions rather than using a single fixed value.
3Reliability
If dead time is increased to account for temperature drift and aging drift, then reliability is improved, but efficiency deteriorates
Solution Approach 1:
The patent uses feedback from temperature sensors and load monitors to dynamically adjust dead time settings. Rather than using a conservative fixed dead time that accounts for worst-case temperature and aging scenarios, the system continuously adapts dead time based on actual operating conditions. This allows minimal dead time during stable operation (improving efficiency) while maintaining adequate margins when environmental factors require it (preserving reliability).
Solution Approach 2:
The patent implements preliminary characterization of component behavior under temperature and aging effects. During manufacturing or initial operation, the system establishes baseline parameters for temperature drift and aging drift. These pre-determined characteristics enable the control unit to predict when adjusted dead time is needed, rather than always using excessive dead time. This preliminary action allows the system to prepare optimal dead time settings in advance of actual operating conditions.
Data Source
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AI summary
In order to increase efficiency, the invention provides for a switched-mode power supply (100), which comprises input connections (101, 102) for receiving an input voltage and/or an input current, output connections (103, 104) for providing an output voltage and/or an output current, a circuit arranged between the input and output connections for current and/or voltage conversion comprising at least one controllable switch, a control unit (200) for activating the at least one controllable switch by means of at least one pulse width modulation signal having a variable frequency and a variable duty cycle, and measuring devices (151, 141, 153, 143) connected to the control unit (200), at least designed to measure the input amperage, the input voltage, the output amperage, and the output voltage, wherein the control unit (200) is designed to monitor the efficiency of the switched-mode power supply (100) by means of measured values of the connected measuring devices, and to optimize the efficiency by means of a first digital control circuit by activating the at least one controllable switch. The invention further provides for a method for operating such a switched-mode power supply (100).