Multidimensional PWM Control for Buck Converter Transient Stability
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Solution Overview
Problem
Conventional PWM controllers face limitations in simultaneously controlling pulse width and switching frequency, leading to issues like output voltage overshoot, current imbalance, and chaotic responses, which affect the efficiency and stability of high-power ICs and multiphase buck converters.
Innovation Solution
A multidimensional PWM control method where both pulse width (Ton) and switching frequency (Fsw) are continuously adjusted based on error voltage feedback, using correlated gain transfer functions to generate modulation signals for effective duty cycle modulation, enabling concurrent control of Ton and Fsw to achieve superior response and stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If conventional PWM controllers use fixed frequency control, then the control system is simple to implement, but the output voltage regulation precision deteriorates due to overshoot and chaotic responses
Solution Approach 1:
The patent implements dynamic PWM control where both the pulse width (Ton) and switching frequency (Fsw) are continuously adjusted based on error voltage feedback. The controller transitions from fixed-frequency operation to variable-frequency operation, allowing the system to adapt switching parameters in real-time to minimize output voltage overshoot and improve regulation precision during transient conditions.
Solution Approach 2:
The patent changes the operating parameters of the PWM controller by simultaneously varying both Ton and Fsw based on the error voltage magnitude and frequency. The controller uses gain transfer functions to convert error voltage into adjusted Ton and Fsw values, enabling precise control of the effective duty cycle (Deff=Ton×Fsw) to maintain output voltage within the targeted regulation window.
2Speed
If the controller simultaneously adjusts Ton and Fsw, then the transient response improves, but the device complexity increases due to multidimensional control requirements
Solution Approach 1:
The patent extends conventional one-dimensional PWM control (varying only Ton at fixed Fsw) to two-dimensional control by simultaneously varying both Ton and Fsw. The controller uses separate gain transfer functions (first gain for Ton adjustment, second gain for Fsw adjustment) that process error voltage to generate independent adjustment signals for both parameters, enabling superior transient response through coordinated two-parameter modulation.
Solution Approach 2:
The patent implements closed-loop feedback control where the controller continuously monitors output voltage, calculates error voltage, and uses this feedback to dynamically adjust both Ton and Fsw. The feedback mechanism ensures that simultaneous adjustment of both parameters responds accurately to load changes and maintains output voltage regulation, with the error voltage frequency also influencing the adjustment strategy.
3Reliability
If additional margining is applied to maintain output voltage regulation, then the regulation window is maintained, but the efficiency deteriorates due to excess margining requirements
Solution Approach 1:
The patent enables the control system to self-regulate output voltage within the targeted regulation window through precise multidimensional PWM control, reducing or eliminating the need for additional conservative margining. By simultaneously optimizing Ton and Fsw based on real-time error voltage, the system achieves reliable regulation without requiring excessive margin headroom, thereby improving efficiency.
Data Source
AI summary
An apparatus includes a controller that monitors an error voltage indicating a difference between an output voltage and a setpoint voltage. Based on the monitored error voltage, the controller generates modulation adjustment signals including a frequency adjustment signal and an ON-time adjustment signal. The controller modulates a pulse width modulation signal of a first power supply phase in accordance with both the frequency modulation adjustment signal and the ON-time adjustment signal.