Switched Mode Power Supply Reference Voltage Control
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Solution Overview
Problem
Switched mode power supplies face challenges in efficiently regulating output voltages with variable input voltages due to limitations in existing control methods, particularly in maintaining high efficiency across varying conditions.
Innovation Solution
The method involves generating a control signal with a duty cycle using a reference voltage, which is adjusted based on the duty cycle's range, input voltage, and temperature to optimize the duty cycle for high efficiency, employing a control circuit that selects and adjusts the reference voltage to maintain the duty cycle within a defined range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a fixed reference voltage is used for control, then the control circuit is simple, but the duty cycle cannot be optimized across varying input voltages and temperatures
Solution Approach 1:
The reference voltage is changed from a fixed value to a dynamic value that varies based on operating conditions. The control circuit dynamically selects and adjusts the reference voltage according to input voltage levels and temperature, enabling the duty cycle to be optimized for different operating conditions while maintaining circuit feasibility.
Solution Approach 2:
The reference voltage parameter is made adjustable based on operating conditions. The control circuit monitors input voltage and temperature, then selects appropriate reference voltage values from multiple options or adjusts the reference voltage to optimal levels, thereby optimizing the duty cycle without requiring complete redesign of the control architecture.
2Loss of energy
If the duty cycle is allowed to vary freely, then the control is flexible, but power conversion efficiency decreases due to excessive power losses
Solution Approach 1:
The control circuit implements feedback by monitoring the duty cycle and comparing it against optimal ranges. When the duty cycle deviates from the optimal range that minimizes power losses, the control circuit adjusts the reference voltage to bring the duty cycle back into the efficient operating range, thereby reducing power conversion losses while maintaining necessary control flexibility.
Solution Approach 2:
The reference voltage parameter is adjusted based on the actual duty cycle operating conditions. By changing the reference voltage to match optimal operating points, the system minimizes power losses in the power switches and other components while retaining the ability to adapt to different load and input voltage conditions.
3Loss of energy
If a single reference voltage is used, then the design is simple, but efficiency is compromised under varying input voltage and temperature conditions
Solution Approach 1:
The reference voltage generation is segmented into multiple discrete reference voltage levels instead of using a single reference voltage. The control circuit selects the appropriate reference voltage level based on the current operating conditions (input voltage and temperature), thereby optimizing efficiency across different conditions without requiring a continuously variable reference voltage source.
Solution Approach 2:
The control circuit is designed to handle multiple functions: monitoring input voltage, sensing temperature, selecting appropriate reference voltage levels, and adjusting the duty cycle accordingly. This multi-functional approach allows the system to optimize power loss across varying conditions while consolidating control logic into a single integrated control circuit.
Data Source
AI summary
Methods of regulating an output voltage of a switched mode power supply having a variable input voltage and a power switch include adjusting a reference voltage to adjust a duty cycle of a control signal for the power switch. The reference voltage may be adjusted as a function of the duty cycle, in response to the duty cycle of the control signal being outside a defined range and/or in the response to a temperature within the switched mode power supply being above a threshold temperature. Other methods include selecting a reference voltage from a plurality of reference voltages based on a determined input voltage and generating a control signal for the power switch as a function of the selected reference voltage to adjust the duty cycle of the control signal. Switched mode power supplies and control circuits for implementing the methods are also disclosed.