Power Converter Mode Switching to Minimize PWM-PFM Voltage Ripple
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Solution Overview
Problem
Existing power converting devices experience significant voltage ripple during mode switching between pulse frequency modulation (PFM) and pulse width modulation (PWM) modes, leading to potential deterioration of circuit elements.
Innovation Solution
A power converting device with a pulse width modulation control circuit that adjusts voltage levels based on inductor current and capacitor voltage during mode switching, using a current sensor, ramp output portion, current controller, adder, and comparator to minimize voltage ripple.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the power converting device operates in PFM mode at light load, then operating efficiency is improved, but output voltage ripple increases significantly
Solution Approach 1:
The power converting device dynamically switches between PFM and PWM modes based on load conditions. The control circuit monitors load current and automatically selects PFM mode for light loads (high efficiency) and PWM mode for heavy loads (low ripple), making the system adaptable to different operating conditions rather than fixed in one mode
Solution Approach 2:
The invention changes the operating parameters (modulation mode) based on load conditions. By detecting load current levels, the system transitions between different modulation strategies - using frequency modulation at light loads and pulse width modulation at heavy loads - thereby optimizing both efficiency and voltage stability across the entire load range
2Object-affected harmful factors
If the power converting device operates in PWM mode at heavy load, then output voltage ripple is reduced, but operating efficiency decreases
Solution Approach 1:
The system dynamically adjusts its operating mode based on real-time load conditions. Instead of permanently operating in PWM mode, the control circuit continuously monitors load current and switches to PFM mode when load decreases, thereby achieving low ripple when needed and high efficiency when load is light
Solution Approach 2:
The invention changes the modulation parameter (mode selection) based on load current levels. At heavy loads, PWM mode provides stable voltage with acceptable efficiency. As load decreases, the system transitions to PFM mode to maximize efficiency, thus optimizing the trade-off between ripple and efficiency across different operating points
3Adaptability or versatility
If mode switching between PFM and PWM occurs, then adaptability to load changes is improved, but significant voltage ripple is generated during switching
Solution Approach 1:
The control circuit prepares for mode transitions by monitoring load current in advance. Before switching between PFM and PWM modes, the system detects load changes and proactively initiates the transition, ensuring smooth handover and preventing abrupt voltage fluctuations that would cause ripple
Solution Approach 2:
The invention employs feedback control where the control circuit continuously monitors output voltage and load current. During mode transitions, this feedback mechanism detects voltage deviations and adjusts switching timing or duty cycle accordingly, suppressing ripple generation while maintaining adaptability to load changes
Data Source
AI summary
A power converting device, a signal processing device, and an electronic device including the same are disclosed. The power converting device includes a first switching element and a second switching element; a pulse width modulation (PWM) control circuit to output a PWM control signal based on a first voltage corresponding to a current flowing in an inductor having one end connected to the first and second switching elements or a second voltage corresponding to a voltage of a capacitor connected to the other end of the inductor; and a pulse frequency modulation (PFM) control circuit to output a PFM control signal based on the current flowing in the inductor or the voltage of the capacitor, wherein the PWM control circuit is configured to adjust the first voltage, during mode switching between a PFM mode and a PWM mode.