Voltage Converter Inductor Charging Time Control

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Solution Overview

Problem

Existing power supply devices, such as voltage converters, face challenges in achieving high power transfer efficiency and stable mode transitions across varying load currents, particularly in switching between pulse-width modulation (PWM) and pulse-frequency modulation (PFM) modes.

Innovation Solution

A voltage converter with a switching control circuit that adjusts the charging time of an inductor based on input voltage and feedback signals, using pulse-width modulation (PWM) and pulse-frequency modulation (PFM) to select between operation modes based on current sensing signals, ensuring efficient power transfer and stable mode transitions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of energy

If a voltage converter uses fixed switching mode (either PWM or PFM), then the control circuit is simple, but power transfer efficiency decreases across varying load currents

Engineering Contradiction:

Improvepower transfer efficiencyVSAvoidswitching control circuit complexity

Core Design Contradiction:

Loss of energyVSDevice complexity

Solution Approach 1:

The voltage converter dynamically switches between PWM and PFM modes based on operating conditions. The controller monitors the relationship between input voltage and reference voltage, and automatically selects the appropriate modulation mode to optimize power transfer efficiency across varying load currents and input voltage conditions.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The system changes the switching control parameter (modulation mode) based on input voltage levels. When input voltage is high relative to reference voltage, PFM mode is selected; when input voltage is low, PWM mode is selected. This parameter change optimizes efficiency across different operating points.

Inventive Principle:

Principle #35Parameter changes

2Loss of energy

If the voltage converter switches between PWM and PFM modes, then power transfer efficiency increases, but mode transition stability becomes challenging

Engineering Contradiction:

Improvepower transfer efficiencyVSAvoidmode transition stability

Core Design Contradiction:

Loss of energyVSStability of the object's composition

Solution Approach 1:

The controller uses feedback from the input voltage sensor and reference voltage comparison to determine when to switch between PWM and PFM modes. This feedback mechanism ensures stable mode transitions by continuously monitoring operating conditions and switching only when appropriate thresholds are crossed, preventing oscillation between modes.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The system performs preliminary comparison of input voltage with reference voltage before initiating mode switching. The controller anticipates the need for mode change by monitoring voltage conditions in advance, ensuring smooth and stable transitions rather than abrupt changes that could cause instability.

Inventive Principle:

Principle #10Preliminary action

3Loss of energy

If the voltage converter uses pulse-frequency modulation (PFM) mode, then power transfer efficiency improves at light loads, but the switching frequency varies which may cause instability

Engineering Contradiction:

Improvepower transfer efficiencyVSAvoidswitching frequency stability

Core Design Contradiction:

Loss of energyVSSpeed

Solution Approach 1:

The voltage converter dynamically adjusts switching frequency in PFM mode based on load conditions. At light loads, the lower frequency improves efficiency by reducing switching losses. The system acceptably varies frequency because the trade-off of improved efficiency at light loads outweighs the frequency instability, and the variation is controlled within acceptable ranges.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The PFM mode uses periodic switching with variable period (frequency) to optimize efficiency. The switching frequency is modulated periodically based on the energy transfer requirements, allowing the system to operate efficiently at different power levels by adjusting the timing of energy transfer cycles.

Inventive Principle:

Principle #19Periodic action

4Speed

If the voltage converter uses pulse-width modulation (PWM) mode, then switching frequency remains stable, but power transfer efficiency decreases at light loads

Engineering Contradiction:

Improveswitching frequency stabilityVSAvoidpower transfer efficiency

Core Design Contradiction:

SpeedVSLoss of energy

Solution Approach 1:

The voltage converter dynamically selects between PWM and PFM modes based on load conditions. PWM mode provides stable switching frequency suitable for heavy loads where efficiency is less sensitive to frequency variations. The system switches to PFM mode at light loads to recover efficiency, using dynamic mode selection to balance frequency stability and efficiency requirements.

Inventive Principle:

Principle #15Dynamics

Data Source

PatentUS10069412B2Voltage converter for power management

Publication Date: 2018.09.04 SAMSUNG ELECTRONICS CO LTD

AI summary

A voltage converter includes a converting circuit and a switching control circuit, where the converting circuit includes an inductor connected to a switching node, a first switching device connected between the switching node and a common voltage and a second switching device connected to the switching node, where the first switching device charges the inductor and discharges the inductor in response to a control signal, and the switching control circuit generates the control signal by performing a PWM and a PFM based on a first sensing signal, a second sensing signal and a feedback signal, and adjusts a charging time of the inductor on a time basis, based on at least the input power supply voltage when the switching control circuit performs the PFM.