Input Current Smoothing via PWM Window Shifting

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Fully regenerative power delivery systems face inefficiencies and high costs due to distortion issues caused by active front ends, which are exacerbated by the need for bulky and expensive line reactors to smooth input current, and often provide more regeneration capability than required for applications with limited needs.

Innovation Solution

A method that evaluates input current for fundamental cycles and adjusts a window relative to the input voltage waveform to smooth the current, allowing for shifting in either direction based on smoothness comparisons, eliminating the need for line reactors by controlling switching devices through pulse width modulation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-generated harmful factors

If line reactors are used to smooth input current, then input current distortion is reduced, but system size and cost increase

Engineering Contradiction:

Improveinput current distortionVSAvoidsystem size

Core Design Contradiction:

Object-generated harmful factorsVSWeight of stationary object

Solution Approach 1:

The patent replaces the mechanical/physical solution of using line reactors (inductive components) with an electronic control solution using pulse width modulation (PWM) of switching devices. The PWM control actively shapes the input current waveform to match the voltage waveform, achieving current smoothing without physical reactors, thereby reducing system size while maintaining distortion reduction benefits

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent changes the operational parameters of the power conversion system by implementing PWM control with variable switching patterns. By dynamically adjusting the switching duty cycle and timing of the switching devices, the system can control the input current characteristics to be sinusoidal and in-phase with voltage, achieving distortion reduction through parameter control rather than passive components

Inventive Principle:

Principle #35Parameter changes

2Object-generated harmful factors

If line reactors are used to smooth input current, then input current distortion is reduced, but system cost increases

Engineering Contradiction:

Improveinput current distortionVSAvoidsystem cost

Core Design Contradiction:

Object-generated harmful factorsVSEase of manufacture

Solution Approach 1:

The patent replaces expensive passive line reactor components with electronic PWM control circuitry. This substitution eliminates the need for bulky inductors and associated magnetic materials, reducing component costs, assembly complexity, and overall system price while achieving the same distortion reduction function through intelligent switching control

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent employs PWM control algorithms that can be implemented through software or simple control circuitry, replacing expensive passive components. The control method uses computational resources and switching devices that are more cost-effective than high-power line reactors, achieving distortion reduction at lower manufacturing cost

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

3Adaptability or versatility

If a fully regenerative system is used, then regeneration capability is maximized, but system cost increases for applications with limited regeneration needs

Engineering Contradiction:

Improveregeneration capabilityVSAvoidsystem cost

Core Design Contradiction:

Adaptability or versatilityVSEase of manufacture

Solution Approach 1:

The patent implements a dynamic power delivery system where the regeneration capability can be adjusted in real-time based on application requirements. By dynamically controlling the switching devices and adjusting the PWM duty cycle, the system can operate in fully regenerative mode when needed and reduce regeneration activity when not required, optimizing cost-effectiveness while maintaining adaptability

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The patent changes the operational parameters of the power conversion system to match regeneration needs. By adjusting the PWM switching patterns and control parameters, the system can provide full regeneration capability when required and reduce regeneration activity for limited needs, avoiding the cost of always having maximum regeneration capability while maintaining the ability to scale when needed

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentUS7414866B2Method for smoothing input current to a power delivery system having regeneration capability

Publication Date: 2008.08.19 INNOMOTICS GMBH

AI summary

A method for smoothing input current to a power delivery system having regeneration capability. The method comprises evaluating input current to an input converter of the power delivery system for a first fundamental cycle, and shifting a window relative to a waveform of an input voltage after the first fundamental cycle. The method also comprises evaluating input current to the input converter for a second fundamental cycle, and determining whether the input current of the second fundamental cycle is smoother than the input current of the first fundamental cycle. The method further comprises shifting the window in the same direction the window was shifted after the first fundamental cycle if the input current of the second fundamental cycle is smoother than the input current of the first fundamental cycle, and shifting the window in the opposite direction the window was shifted after the first fundamental cycle if the input current of the second fundamental cycle is not smoother than the input current of the first fundamental cycle.