UPS Rectifier Relay Layout for Low-Cost SCR-Free Switching

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Solution Overview

Problem

Existing uninterruptible power supplies (UPS) with SCR-based mode switching suffer from high circuit costs due to large SCR losses and the need for an isolated drive circuit, which increases costs and complexity.

Innovation Solution

The UPS employs a rectifier with interleaved parallel connections of rectifier diodes and alternating current side relays, along with a DC/DC conversion unit and a charging circuit, eliminating the need for an additional drive circuit and reducing SCR losses, thereby minimizing circuit costs and sizes of input and output filters.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If SCR-based mode switching is used, then switching reliability is improved, but circuit cost increases due to large SCR losses and need for isolated drive circuit

Engineering Contradiction:

Improveswitching reliabilityVSAvoidcircuit cost

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent extracts the SCR and its isolated drive circuit from the mode switching mechanism, replacing them with a simpler relay-based switching system. The rectifier diodes are separated into multiple groups that can be independently controlled by relays, eliminating the need for SCR components and their associated drive circuits, thus reducing circuit cost while maintaining switching reliability.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent replaces expensive SCR components with cheaper relay switches and rectifier diodes. The relay-based switching mechanism uses conventional, low-cost components instead of costly SCR devices, significantly reducing the overall circuit cost while achieving the same mode switching function.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

2Speed

If SCR is used for mode switching, then switching speed is improved with no delay, but energy loss increases due to large SCR losses

Engineering Contradiction:

Improveswitching speedVSAvoidSCR loss

Core Design Contradiction:

SpeedVSLoss of energy

Solution Approach 1:

The patent replaces energy-intensive SCR components with more energy-efficient relay switches and rectifier diodes. The relay-based switching mechanism consumes significantly less energy during operation, eliminating the large SCR losses while maintaining effective switching performance.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

3Measurement precision

If isolated drive circuit is added for SCR control, then control precision is improved, but device complexity increases leading to high circuit costs

Engineering Contradiction:

Improvecontrol precisionVSAvoidcircuit complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent removes the isolated drive circuit from the system by replacing SCR with relay-based switching. The relay control mechanism uses standard control signals without requiring complex isolated drive circuits, thereby reducing circuit complexity while maintaining adequate control precision for mode switching operations.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent replaces complex isolated drive circuitry with simple relay control mechanisms. The relay switches can be controlled by conventional control signals, eliminating the need for expensive and complex isolated drive circuits while maintaining sufficient control precision for the application.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

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 reduces circuit costs and improves stability by minimizing SCR losses and eliminating the need for an additional drive circuit, while ensuring smooth transitions between mains and battery modes without voltage drops.

Implementation Method 1

The rectifier includes six first rectifier diodes, six second rectifier diodes... Each of the three phases of alternating current input ends is connected to one end of one of the three alternating current side relays. The other end of each of the three alternating current side relays is connected to anodes of two first rectifier diodes

Methodology Applied

Scientific EffectRectification: Diode

Implementation Method 2

The rectifier includes three alternating current side relays, six direct current side relays... control the three alternating current side relays to turn off; after controlling the three alternating current side relays to turn off for first preset duration, control the six direct current side relays to turn on

Methodology Applied

Scientific EffectElectromagnetic actuation: Relay

Data Source

PatentUS12476481B2Uninterruptible power supply

Publication Date: 2025.11.18 HUAWEI DIGITAL POWER TECH CO LTD

AI summary

An uninterruptible power supply. A rectifier of the uninterruptible power supply includes six first rectifier diodes, six second rectifier diodes, three alternating current side relays, six direct current side relays, a DC/DC conversion unit, and a controller. The other end of each alternating current side relay is connected to anodes of two first rectifier diodes, and cathodes of the two first rectifier diodes are respectively connected to two phases of positive input ends of the DC/DC conversion unit. The other end of each alternating current side relay is further connected to cathodes of two second rectifier diodes, and anodes of the two second rectifier diodes are respectively connected to two phases of negative input ends of the DC/DC conversion unit.