Phase Adjustment Circuit for Power Converter Transient Response
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Solution Overview
Problem
Conventional power converters with constant on time (COT) control architecture experience delayed energy compensation due to small equivalent serial resistance of inductors and capacitors, leading to oscillations in output voltage waveforms due to delayed feedback and error signals.
Innovation Solution
A phase adjustment circuit that generates a delay signal and amplifies the difference between the error signal and the delay signal to produce a control signal, which is used to compensate for phase delays, thereby stabilizing the output voltage and improving transient response.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If conventional COT control architecture is used with small equivalent serial resistance of inductor and capacitor, then power converter operates with fixed frequency and simple circuit structure, but energy compensation is delayed causing output voltage oscillation and poor transient response
Solution Approach 1:
The phase adjustment circuit performs preliminary phase lead adjustment on the error signal before it is used for PWM generation. By anticipating the phase delay that will occur due to small ESR and DCR values, the circuit proactively shifts the phase of the control signal forward, so that when the delayed feedback arrives, the system is already in the correct state to maintain stability and prevent oscillation.
2Productivity
If conventional COT control is used, then fixed on-time PWM generation is achieved, but transient response is slow and output voltage converges slowly due to delayed feedback signal
Solution Approach 1:
The phase adjustment circuit performs preliminary phase lead adjustment on the error signal before it is used for PWM generation. By anticipating the phase delay that will occur due to small ESR and DCR values, the circuit proactively shifts the phase of the control signal forward, so that when the delayed feedback arrives, the system is already in the correct state to maintain stability and prevent oscillation.
Data Source
AI summary
A phase adjustment circuit of a power converter, the power converter, and a control method of the power converter are provided. The control method includes following steps. A delay signal is generated according to an error signal, and the error signal is associated with an output voltage of the power converter. A difference between the error signal and the delay signal is amplified. A control signal is provided according to the amplified difference and the error signal, and a phase of the control signal leads a phase of the error signal. The control signal serves to improve a response speed of the power converter.