Electrolyzer Rectifier Control for Harmonic Absorption and Power Factor

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Solution Overview

Problem

Power quality issues such as poor power factors and higher harmonic content in electrical grids are costly to mitigate, particularly due to non-unity power factor loads like non-PFC rectifiers, motors, and capacitors.

Innovation Solution

An electrolyzer power control system that integrates power factor correction and harmonic absorption into rectifier control, thereby improving grid power quality and reducing the need for separate harmonic filtering equipment.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If non-PFC rectifiers, motors and capacitors are used as loads, then the system operates with simple and inexpensive equipment, but poor power factors and higher harmonic content are induced in the grid

Engineering Contradiction:
Improvesimplicity and cost of equipmentVSAvoidharmonic content and power factor degradation
Core Design Contradiction:
Ease of manufactureVSObject-generated harmful factors

Solution Approach 1:

The patent combines power factor correction and harmonic absorption functions into a single integrated control system for the electrolyzer rectifier. The controller simultaneously performs unity power factor correction and absorbs harmonic currents from the grid, eliminating the need for separate PFC circuits and harmonic filters while maintaining both functions effectively

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The electrolyzer rectifier control system is designed to perform multiple functions: it converts AC to DC power for the electrolyzer, corrects power factor to unity, absorbs harmonic currents from the grid, and provides reactive power support. This multi-functional approach replaces traditional separate equipment with a single versatile control system

Inventive Principle:
Principle #6Universality (Multi-functionality)

2Object-generated harmful factors

If independent dedicated equipment such as passive filters, harmonic trap filters and active harmonic filters are used, then harmonic content and power factor issues are mitigated, but cost and space/area increase

Engineering Contradiction:
Improveharmonic content and power factor degradationVSAvoidnumber and type of dedicated equipment
Core Design Contradiction:
Object-generated harmful factorsVSDevice complexity

Solution Approach 1:

The patent merges the functions of power factor correction and harmonic filtering into the electrolyzer's existing rectifier control system. The controller uses grid voltage and current measurements to generate reference currents that simultaneously achieve unity power factor and absorb harmonics, eliminating the need for separate PFC circuits and harmonic trap filters

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The electrolyzer rectifier system serves itself by using its own control system to correct power factor and absorb harmonics. The controller measures grid conditions, calculates appropriate current references, and adjusts the rectifier output to provide both active and reactive power while maintaining unity power factor, making the system self-sufficient without external filtering equipment

Inventive Principle:
Principle #25Self-service

Data Source

PatentEP4568049A1Electrolyzer power control with harmonic absorption
Publication Date: 2025.06.11 BLOOM ENERGY CORP
  • EP4568049A1 patent drawingFigure 1A
  • EP4568049A1 patent drawingFigure 1B
  • EP4568049A1 patent drawingFigure 2

AI summary

Provided is an electrolyzer power control system that includes a reactive harmonic current reference generation stage. The reactive harmonic current reference generation stage selects a reactive power set point for reactive power drawn by a rectifier from a grid, determines a reactive power current reference based on the reactive power set point, aggregates the reactive power current reference with a reference current of harmonic currents that the rectifier injects in or draws from the grid, determines a reactive harmonic current reference that compensates for both the reactive power and the harmonic currents and outputs the reactive harmonic current reference. Switching signals that operate the rectifier are generated based on the reactive harmonic current reference.