AC to DC Converter Parallel Capacitor Voltage Regulation

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Solution Overview

Problem

Existing AC to DC converters require large capacitors to maintain bus voltage, leading to increased size and inefficiency, as they struggle to efficiently manage voltage variations across different AC power sources and loads.

Innovation Solution

The AC to DC converter employs a parallel converter and bulk capacitor configuration, where the controller operates in modes to store and discharge energy, allowing for reduced capacitance and size, using a smaller ceramic capacitor instead of large electrolytic ones, and efficiently managing voltage through boost, buck, and shorting modes.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If large capacitors are used to maintain bus voltage, then voltage stability is improved, but device size increases

Engineering Contradiction:

Improvebus voltage stabilityVSAvoidconverter size

Core Design Contradiction:

ReliabilityVSVolume of stationary object

Solution Approach 1:

The patent divides the capacitor function into two separate components: a small bulk capacitor for high-frequency voltage regulation and a parallel converter for low-frequency voltage support. This segmentation allows the system to achieve voltage stability without requiring a large single capacitor, thus reducing overall device size while maintaining reliability.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The parallel converter acts as an intermediary between the rectifier and the bulk capacitor, providing voltage support during low-line conditions. This intermediary component enables the system to maintain bus voltage stability without relying solely on a large bulk capacitor, thereby reducing the required capacitance and device size.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If large capacitors are used to maintain bus voltage, then voltage stability is improved, but manufacturing cost increases

Engineering Contradiction:

Improvebus voltage stabilityVSAvoidmanufacturing cost

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

By segmenting the voltage support function between a small bulk capacitor and a parallel converter, the system eliminates the need for large, expensive electrolytic capacitors. This segmentation reduces component costs and simplifies manufacturing while maintaining voltage stability through coordinated operation of the two components.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent replaces expensive, large electrolytic capacitors with a combination of a small, inexpensive ceramic bulk capacitor and a relatively simple parallel converter circuit. This substitution uses cheaper components to achieve the same voltage stability function, reducing manufacturing cost.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

3Device complexity

If traditional capacitor-based voltage maintenance is used, then simplicity is maintained, but adaptability to varying AC power sources decreases

Engineering Contradiction:

Improvecircuit simplicityVSAvoidadaptability to AC power sources

Core Design Contradiction:

Device complexityVSAdaptability or versatility

Solution Approach 1:

The parallel converter introduces dynamic control capability to the system, allowing it to adapt to varying AC power source conditions (such as low-line voltage) by actively regulating voltage through controlled switching. This dynamic operation enables the system to maintain performance across different input conditions while keeping the bulk capacitor small.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The system changes operating parameters dynamically by switching the parallel converter on and off based on bus voltage conditions. This parameter change approach allows the converter to adapt to different AC power source characteristics and load conditions, improving versatility without significantly increasing circuit complexity.

Inventive Principle:

Principle #35Parameter changes

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

This configuration significantly reduces the size of the converter while maintaining bus voltage above a specified level, enhancing efficiency and adaptability to varying AC power sources and loads.

Implementation Method 1

a bulk capacitor coupled to the parallel converter

Methodology Applied

Scientific EffectCapacitance: Capacitance

Implementation Method 2

a parallel converter connected between the positive line and the negative line of the bus

Methodology Applied

Scientific EffectElectromagnetic induction: Electromagnetic Induction

Data Source

PatentUS11482944B2AC to DC converter with parallel converter

Publication Date: 2022.10.25 HUAWEI DIGITAL POWER TECH CO LTD

AI summary

An apparatus having an AC rectifier configured to generate one or more rectified signals from an alternating current (AC) signal, bus having a positive line and a negative line, parallel converter connected between the positive line and the negative line, and bulk capacitor coupled to the parallel converter. The bus is connected to the AC rectifier to receive a first of the rectified signals between the positive line and the negative line. The apparatus has a controller configured to operate the parallel converter in a first mode in which energy from a second of the rectified signals from the AC rectifier is stored in the bulk capacitor and a second mode in which the energy stored in the bulk capacitor is discharged to the bus to increase a voltage on the bus during at least an initial portion of the second mode.