DC/DC Converter Switching Frequency Control for Light Source
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Solution Overview
Problem
Existing DC/DC voltage converters struggle to rapidly change current in light sources, leading to overshoot responses and increased power consumption, particularly during polarity reversals and color changes in projection systems, resulting in undesirable light emission and noise.
Innovation Solution
A method involving closed-loop control of a DC/DC voltage converter, where the switching frequency is increased before rapid changes, a retention time is waited, a new setpoint value is set, and then the frequency is lowered, allowing the converter to respond more quickly to current changes and reduce overshoot.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the DC/DC voltage converter uses a standard switching frequency, then the converter operates efficiently under normal conditions, but it cannot respond rapidly to rapid changes in setpoint value, causing overshoot
Solution Approach 1:
The switching frequency of the DC/DC voltage converter is made dynamic rather than fixed. The control device increases the switching frequency above the normal operating frequency when rapid changes in the setpoint value are anticipated or detected, enabling the converter to respond more quickly to setpoint changes and reduce overshoot, then returns it to the normal frequency for efficient steady-state operation.
Solution Approach 2:
The switching frequency parameter is changed adaptively based on operating conditions. The control device monitors the setpoint value changes and adjusts the switching frequency parameter accordingly - increasing it during transient conditions requiring rapid response and maintaining normal values during steady-state operation, thus optimizing both response speed and energy efficiency.
2Speed
If the switching frequency is increased to improve response speed, then rapid changes in current are achieved, but power loss and heat generation increase
Solution Approach 1:
The increased switching frequency is applied periodically or temporarily only when rapid current changes are needed, rather than continuously. The control device activates the high-frequency mode during transient periods when setpoint changes occur and switches back to normal frequency during steady-state periods, thus achieving rapid response when needed while minimizing continuous energy consumption.
Solution Approach 2:
The switching frequency is dynamically adjusted based on the operational requirements. The control device increases frequency temporarily during transitions and maintains normal frequency during steady operation, optimizing the balance between response speed and energy consumption by applying high frequency only when necessary.
3Loss of energy
If the DC/DC voltage converter responds slowly to setpoint changes, then energy loss is reduced, but the light source emits undesirable light and noise increases
Solution Approach 1:
The control device anticipates rapid setpoint changes and proactively increases the switching frequency before the actual change occurs or as it begins, preparing the converter to respond more quickly. This preliminary action prevents overshoot and the associated harmful effects (noise and undesirable light emission) while maintaining energy efficiency during normal operation.
Solution Approach 2:
The switching frequency is dynamically adapted to match the operational demands. During transient conditions where rapid response is needed to prevent harmful effects, the frequency increases temporarily; during steady-state operation where efficiency is paramount, the frequency remains at normal levels, thus balancing efficiency with harm prevention.
Data Source
AI summary
A method for the closed-loop control of the operation of a light source which is supplied with power by a DC/DC voltage converter, a manipulated variable being regulated by a setpoint value for an operational parameter of the DC/DC voltage converter being input, wherein the method comprises the steps of: increasing the switching frequency of the DC/DC voltage converter by an increase value prior to rapid changes in the setpoint value; waiting for a retention time; setting the new setpoint value; waiting for the end of a total retention time; and lowering the switching frequency of the DC/DC voltage converter by the increase value.