DC/DC Converter Transient Response via Dynamic Feed-Forward
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Solution Overview
Problem
Conventional DC/DC converters, both analog and digital PWM controllers, face challenges in quickly responding to transient changes in input voltage due to limitations in feedback loop design and signal isolation, leading to delayed responses and inaccurate reflection of input voltage changes.
Innovation Solution
A DC/DC converter system with an output voltage regulation circuit, a PWM generator, a detection circuit, and a CBC regulation circuit, where the first duty cycle signal and control signal are synchronized, allowing for rapid detection of transient changes in input voltage using feedback signals like input voltage, output voltage, and output current, enabling response within several clock cycles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a traditional analog PWM controller with feed forward function is used, then the response to transient change of input voltage is fast, but the circuit cannot distinguish stable state from transient state leading to high feedback gain in stable state
Solution Approach 1:
The patent applies dynamics by making the feed forward circuit's activation dynamic rather than static. The detection circuit dynamically identifies transient states and selectively activates the feed forward circuit only during transient changes, while the CBC regulation circuit takes over during stable states. This dynamic switching resolves the contradiction by enabling fast response during transients while maintaining stable feedback gain during normal operation.
Solution Approach 2:
The patent enhances the traditional feedback mechanism by introducing a dual-loop structure: the original feedback loop for stable state regulation and a new detection loop that identifies transient states. The feedback signal is used to trigger the feed forward function only when transient changes are detected, creating a more intelligent feedback system that adapts to different operating conditions and resolves the contradiction between fast transient response and stable feedback gain.
2Reliability
If identification of stable state is taken into consideration in the feed forward circuit, then the feedback gain stability is improved, but the response time to transient change increases
Solution Approach 1:
The patent applies preliminary action by continuously monitoring the feedback signal to detect transient changes before they affect the output. The detection circuit is always active, preparing to trigger the feed forward circuit immediately when a transient is detected, thus eliminating response delay while maintaining stable feedback gain during normal operation through the CBC regulation circuit.
Solution Approach 2:
The system dynamically switches between two operating modes: CBC regulation mode for stable states and feed forward mode for transient states. This dynamic adaptation allows the system to optimize performance for each state independently, achieving both fast transient response and stable feedback gain without the time loss that would result from continuous stable state identification.
3Reliability
If digital PWM controller with independent control loop is used, then the stable state and transient state can be distinguished, but the response time is too long due to ADC time delay and program execution time
Solution Approach 1:
The patent replaces the software-based digital control approach with a hardware-based detection and control circuit. By using analog comparison circuits and dedicated detection logic instead of ADC conversion and firmware processing, the system eliminates the time delays associated with digital-to-analog conversion and program execution while maintaining the ability to distinguish between stable and transient states through hardware-level signal processing.
Solution Approach 2:
The patent segments the control function into separate dedicated circuits: a detection circuit for identifying transient states, a feed forward circuit for fast transient response, and a CBC regulation circuit for stable state control. This segmentation allows each circuit to be optimized for its specific function and operate in parallel, eliminating the sequential processing delays inherent in digital controllers while maintaining state identification capability.
4Reliability
If secondary side voltage is used as control signal instead of primary side input voltage, then signal isolation problem is solved, but the change of secondary side voltage fails to absolutely reflect the change of input voltage
Solution Approach 1:
The patent uses the secondary side voltage as a feedback signal while maintaining signal isolation through the transformer. The detection circuit processes this isolated feedback signal to identify transient changes in the primary side input voltage. By combining the isolated secondary side measurement with intelligent detection algorithms, the system achieves both signal isolation and accurate input voltage change detection.
Solution Approach 2:
The patent uses the transformer as an intermediary to transfer information from the primary side to the secondary side while maintaining electrical isolation. The detection circuit acts as another intermediary that processes the isolated secondary side voltage signal to extract information about primary side transient changes, thus resolving the contradiction between signal isolation and measurement precision.
Data Source
AI summary
A DC/DC converter and a control method thereof are disclosed. The DC/DC converter comprises: an output voltage regulation circuit configured to regulate an output voltage of the DC/DC converter, so as to output a duty cycle regulation signal; a PWM generator electrically coupled to the output voltage regulation circuit and configured to generate a first duty cycle signal according to a first clock signal and the duty cycle regulation signal; a detection circuit configured to output a control signal according to a second clock signal and a feedback signal, wherein the feedback signal is configured to detect whether or not the transient change of an input voltage of the DC/DC converter occurs; and a CBC regulation circuit electrically coupled to the PWM generator and the detection circuit, and configured to receive the first duty cycle signal and the control signal and output a second duty cycle signal.