Power Supply Device Frequency Adjustment via Segmented PFM Control
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Solution Overview
Problem
Existing power supply devices face challenges in making finer adjustments to the frequency of the pulse driving signal for switching elements while avoiding the use of high-speed electric parts, which leads to increased noise and power consumption.
Innovation Solution
A power supply device with a control unit that includes A/D conversion, processing, and voltage generation circuits to calculate and adjust control command values, generating driving signals with adjustable frequencies through toggle signals and storage elements, allowing for stepless frequency adjustment without requiring high-speed components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the frequency of the clock signal is raised to make the adjustment unit finer for the frequency of the pulse driving signal, then the adjustment precision is improved, but the noise and electric power consumption increase
Solution Approach 1:
The frequency adjustment function is segmented into two independent parts: (1) a low-frequency clock signal generation unit that operates at a fixed, low frequency to minimize noise and power consumption, and (2) a frequency modulation unit that applies PFM control to adjust the pulse driving signal frequency. This segmentation allows fine frequency adjustment without requiring the entire system to operate at high frequency, thus resolving the contradiction between adjustment precision and harmful effects.
Solution Approach 2:
The system implements dynamic frequency modulation through PFM control, where the pulse driving signal frequency is dynamically adjusted based on power supply conditions while the clock signal remains at a fixed low frequency. This dynamic approach enables fine frequency adjustment capability without continuously operating digital circuits at high frequency, thereby reducing noise and power consumption while maintaining precision when needed.
2Adaptability or versatility
If the frequency of the clock signal is raised to make the adjustment unit finer, then the frequency adjustment capability is improved, but high-speed electric parts are required which increase device complexity
Solution Approach 1:
The system separates the frequency adjustment functionality from the clock signal generation. The clock signal is generated at a fixed low frequency using simple digital circuits, while frequency adjustment is achieved through a dedicated PFM control unit that modulates the pulse driving signal. This segmentation allows fine frequency adjustment capability without requiring the entire digital circuit system to operate at high speed, thus avoiding the need for complex high-speed electric parts.
Solution Approach 2:
The PFM control unit acts as an intermediary between the low-frequency clock signal and the pulse driving signal. It receives the low-frequency clock signal and generates the high-frequency pulse driving signal with adjustable frequency through pulse frequency modulation. This intermediary approach enables fine frequency adjustment capability while keeping the actual operating frequency of digital circuits low, thereby avoiding the need for high-speed electric parts and reducing device complexity.
Data Source
AI summary
A power supply device includes a control unit performing PFM control for a switching element, a voltage detection unit detecting an output voltage of a converter, and a signal generation circuit. The control unit calculates a first control command value based on the output voltage, calculates a new first control command value adjusting the output voltage to a target voltage, calculates a difference value therebetween, and outputs a voltage, which has a polarity corresponding to the difference value, for a first output period corresponding to the difference value. The signal generation circuit generates a pulse signal in which a frequency increases or decreases in accordance with a first command value voltage corresponding to a charged voltage at a storage element according to the new first control command value. The switching element is driven by the pulse signal that has a finer adjustment unit frequency.