SMPS Control Topology for Wide Frequency Range Ripple Reduction
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Solution Overview
Problem
Switched mode power supply (SMPS) controllers face challenges in optimizing operation across a wide range of switching frequencies, leading to inefficiencies and increased ripple in the buck-boost mode of operation, which affects the output voltage and inductor current ripple.
Innovation Solution
A dual hysteresis control scheme is implemented, transitioning between buck, boost, and buck-boost modes based on time domain and voltage domain controls, minimizing the duration in buck-boost mode and reducing inductor current ripple across a wide range of frequencies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the SMPS controller operates in buck-boost mode across a wide range of switching frequencies, then the power supply can handle varying input voltage conditions, but the inductor current ripple and output voltage ripple increase significantly
Solution Approach 1:
The control method segments the operation into distinct time domains: a first time domain where the switch operates at a first switching frequency, and a second time domain where the switch operates at a second switching frequency. This segmentation allows the system to adapt to different operating conditions by switching between frequency domains, thereby reducing inductor current ripple while maintaining wide frequency range adaptability.
Solution Approach 2:
The patent implements dynamic switching frequency adjustment by transitioning between different switching frequencies based on operating conditions. The controller dynamically selects the appropriate switching frequency (first or second frequency) depending on the time domain, enabling the system to optimize performance and minimize ripple across a wide range of input voltage conditions.
2Device complexity
If the SMPS controller uses a fixed switching frequency, then the circuit design is simplified, but the system cannot efficiently handle varying input voltage and load conditions
Solution Approach 1:
The patent changes the switching frequency parameter dynamically based on operating conditions. By implementing a dual-frequency switching scheme where the controller selects between a first switching frequency and a second switching frequency, the system achieves adaptability to varying input voltage and load conditions without requiring an overly complex controller design. The parameter change is achieved through time domain-based frequency selection.
3Reliability
If the SMPS operates continuously in buck-boost mode, then it can maintain output voltage regulation across wide input voltage ranges, but the efficiency decreases due to increased ripple and switching losses
Solution Approach 1:
The patent implements periodic action through alternating between different switching frequencies in different time domains. The controller periodically switches between the first switching frequency and the second switching frequency based on time domain conditions, which reduces inductor current ripple and switching losses while maintaining output voltage regulation. This periodic frequency modulation improves efficiency by avoiding continuous operation at suboptimal frequencies.
Data Source
AI summary
Aspects of the disclosure provide for a circuit. In some examples, the circuit includes a timing circuit and a state machine circuit. The timing circuit determines a relationship between a duty cycle of a power converter and a threshold value. The state machine circuit is coupled to the timing circuit and includes a plurality of states including a buck state, a boost state, and a buck-boost state. The state machine circuit transitions among the plurality of states according to time domain control and voltage domain control, based at least partially on the determined relationship between the duty cycle and the threshold value, transitions among the states according to the time domain control when the time domain control indicates an exit from the buck-boost state, and transitions among the states according to the voltage domain control when the voltage domain control indicates the exit from a buck-boost state.