DC-DC Converter Dynamic Peak Current Control

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Solution Overview

Problem

DC-DC voltage converters face performance degradation due to complex timing and threshold issues during mode switching between PWM and PFM modes, especially when loading conditions are near the transition value, leading to instability and efficiency loss.

Innovation Solution

A control method that dynamically adjusts the upper boundary of the inductor current in the PFM mode to maintain performance across varying loading conditions without switching operation modes, using a buck converter as an example to illustrate the adaptive adjustment of inductor current pulses and sleep durations.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If mode switching between PWM and PFM is implemented to handle varying load conditions, then the DC-DC voltage converter can adapt to different loading scenarios, but the complex timing and threshold issues during mode switching cause performance degradation and instability

Engineering Contradiction:

Improveadaptability to load conditionsVSAvoidstability during mode switching

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The patent implements dynamic adjustment of the inductor current upper boundary threshold based on real-time operating conditions. The threshold is no longer fixed but varies dynamically to optimize converter performance across different load conditions while maintaining stable operation. This dynamic parameter adjustment resolves the contradiction by allowing adaptability without the instability associated with mode switching.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The patent changes the parameter of inductor current upper boundary threshold from a fixed value to a dynamically adjustable value. By modifying this critical parameter based on operating conditions, the converter achieves adaptability to varying loads while avoiding the performance degradation and instability that occur during traditional PWM/PFM mode transitions.

Inventive Principle:

Principle #35Parameter changes

2Device complexity

If fixed inductor current upper boundary is used in PFM mode, then the control logic is simple, but the converter performance degrades when loading conditions are near the transition value between PFM and PWM modes

Engineering Contradiction:

Improvecontrol logic complexityVSAvoidconverter efficiency

Core Design Contradiction:

Device complexityVSProductivity

Solution Approach 1:

The patent makes the inductor current upper boundary threshold dynamic rather than fixed. This allows the converter to maintain optimal performance across a wide range of loading conditions without requiring complex mode switching logic. The dynamic threshold adapts to loading conditions, improving efficiency near transition points while keeping the control logic relatively simple.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The converter system automatically adjusts the inductor current upper boundary threshold based on its own operating conditions without requiring external intervention or complex mode detection logic. This self-adjusting mechanism improves efficiency across varying loads while maintaining simple control architecture.

Inventive Principle:

Principle #25Self-service

3Productivity

If frequent mode switching occurs between PWM and PFM, then the converter can respond to load changes, but switching losses increase and overall efficiency decreases

Engineering Contradiction:

Improveresponse to load changesVSAvoidswitching losses

Core Design Contradiction:

ProductivityVSLoss of energy

Solution Approach 1:

The patent maintains continuous optimal operation by dynamically adjusting the inductor current upper boundary threshold, eliminating the need for discontinuous mode switching between PWM and PFM. This continuous adjustment approach keeps the converter operating efficiently across varying loads without the energy losses associated with frequent mode transitions.

Inventive Principle:

Principle #20Continuity of useful action

Solution Approach 2:

By implementing dynamic threshold adjustment, the converter responds smoothly to load changes without abrupt mode transitions. This dynamic approach reduces switching losses by avoiding frequent PWM/PFM mode changes while maintaining the ability to respond effectively to varying loading conditions.

Inventive Principle:

Principle #15Dynamics

Data Source

PatentEP3240171B1DC/DC converter with burst mode using dynamically adjustable peak current control

Publication Date: 2022.05.25 MEDIATEK SINGAPORE PTE LTD

Figure 1~3
Figure 4A~4B
Figure 5A~5B

AI summary

A DC-DC voltage converter (21,31,41) and associated control method capable of operating in pulse frequency modulation mode (PFM) and dynamically adjusting the upper boundary of the inductor current (IL,ub) for peak current control are provided. The DC-DC voltage converter (21,31,41) is electrically connected to an input terminal (Nin) having an input voltage (Vin) and an output terminal (Nout) having an output voltage (Vout). The DC-DC voltage converter (21,31,41) converts the input voltage (Vin) to the output voltage (Vout), and the DC-DC voltage converter (21,31,41) operates in a pulse frequency modulation mode (PFM). The DC-DC voltage converter (21,31,41) includes an inductor (L) and a converting circuit (211,311,411), which are electrically connected to each other. An inductor current (IL) flows through the inductor (L). The converting circuit (211,311,411) adjusts the inductor current (L) according to a setting signal (IL,ub) so that the inductor current is less than or equivalent to an upper boundary of the inductor current (IL,ub).