Buck-Boost Regulator Current Control With Variable Filter Timing
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Solution Overview
Problem
Existing switching voltage regulators face noise issues in the shunt voltage, leading to subharmonics generation and instability, particularly at high inductor currents, due to the inability to effectively filter out noise, compromising the control device's performance.
Innovation Solution
A control device with a variable-time constant filter is introduced, which adjusts its filtering based on the operating mode of the regulator, specifically having a higher time constant in boost mode to effectively filter noise and reduce subharmonics in both boost and buck modes, ensuring stable operation across varying conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a fixed time constant filter is used to filter the shunt voltage, then noise is reduced, but the filter cannot effectively eliminate subharmonics generation at high inductor currents
Solution Approach 1:
The patent applies the dynamics principle by making the filter time constant variable rather than fixed. The control device adjusts the time constant dynamically based on operating conditions, specifically increasing it during boost mode to effectively filter noise and prevent subharmonics generation at high inductor currents, while maintaining shorter time constants in buck mode for faster response.
Solution Approach 2:
The patent implements parameter changes by modifying the filter time constant parameter according to the operating mode of the switching voltage regulator. The time constant is changed from a fixed value to a variable parameter that adapts to different operational requirements, allowing optimal noise filtering and stability maintenance across varying load and input voltage conditions.
2Object-affected harmful factors
If the filter time constant is increased to filter noise, then noise reduction improves, but the response time of the control device increases
Solution Approach 1:
The patent resolves this contradiction by dynamically adjusting the filter time constant based on the operating mode. During boost mode when noise filtering is critical, the time constant is increased to reduce noise effects. During buck mode when fast response is needed, the time constant is decreased to maintain quick control response, thus optimizing both noise filtering and response time under different operating conditions.
Solution Approach 2:
The patent employs periodic adjustment of the filter time constant synchronized with the switching cycles and operating mode transitions. The time constant is periodically modified to match the operational requirements of each switching phase, allowing the system to alternate between aggressive noise filtering when needed and rapid response when the operating conditions demand it.
3Speed
If no filter is used, then the control response is fast, but noise causes subharmonics generation and instability
Solution Approach 1:
The patent applies dynamics by implementing a variable time constant filter that adapts its filtering strength based on operating conditions. The filter is actively engaged with appropriate time constants during boost mode to prevent subharmonics and instability, while maintaining minimal filtering impact during buck mode to preserve fast control response, thus achieving both stability and speed under different operational scenarios.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The variable-time constant filter significantly reduces noise effects on the shunt voltage, preventing subharmonic generation and maintaining regulator stability even at high inductor currents, thus enhancing the overall performance and reliability of the switching voltage regulator.
Implementation Method 1
a capacitive element (104) having a capacitance CF and coupled between the first and the second output nodes (100, 101)
Data Source
AI summary
A control device for a switching voltage regulator of the buck-boost type having a switching circuit. The control device is configured to perform a current-control of the switching circuit and is formed by a filter and a loop control circuit. The filter is configured to be coupled to a resistive element of the switching circuit and to provide a filtered signal starting from a measurement signal indicative of a current flowing through the resistive element. The loop control circuit is configured to generate one or more switching control signals to drive the switching circuit, as a function of the filtered signal. The filter is configured to receive a filter control signal indicative of an actual operating mode of the switching voltage regulator. The filter is variable as a function of the filter control signal.