Microwave Generator Power Factor Correction via Single-Stage Control

Solution Overview

Problem

The high cost and volume of microwave generators due to the inclusion of power factor correction circuits, which are costly and increase the fabricating cost and size of the device.

Innovation Solution

A microwave generator with a single-stage power supply configuration that includes a power converter, a feedback oscillator, a pulse controller, a signal combination circuit, and semiconductor amplifiers, which adjusts the output current to be in phase with the input voltage without a power factor correction circuit, achieving power factor correction.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a power factor correction circuit is included in the microwave generator, then the power factor is corrected and input current follows the input voltage waveform, but the fabricating cost and device volume increase

Engineering Contradiction:

Improvepower factor correctionVSAvoiddevice volume

Core Design Contradiction:

ReliabilityVSVolume of stationary object

Solution Approach 1:

The patent extracts and removes the power factor correction circuit from the microwave generator system. Instead of using a dedicated power factor correction circuit, the invention achieves power factor correction functionality through the existing power converter by controlling the switching timing of the semiconductor switch based on the input voltage waveform, thereby eliminating the need for separate correction circuitry and reducing device volume.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The power converter is designed to perform multiple functions: it simultaneously converts input voltage to output voltage and provides power factor correction. By controlling the semiconductor switch to turn on at the zero-crossing point of the input voltage and using the inductor current to follow the input voltage waveform, the power converter achieves both voltage conversion and power factor correction without requiring separate dedicated circuits.

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Reliability

If a power factor correction circuit is included in the microwave generator, then the power factor is corrected and harmonics are reduced, but the fabricating cost increases

Engineering Contradiction:

Improvepower factor correctionVSAvoidfabricating cost

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The patent extracts and removes the power factor correction circuit from the microwave generator system. Instead of using a dedicated power factor correction circuit, the invention achieves power factor correction functionality through the existing power converter by controlling the switching timing of the semiconductor switch based on the input voltage waveform, thereby eliminating the need for separate correction circuitry and reducing device volume.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The power converter is designed to perform multiple functions: it simultaneously converts input voltage to output voltage and provides power factor correction. By controlling the semiconductor switch to turn on at the zero-crossing point of the input voltage and using the inductor current to follow the input voltage waveform, the power converter achieves both voltage conversion and power factor correction without requiring separate dedicated circuits.

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Reliability

If a two-stage configuration with power factor correction circuit is used, then power factor correction is achieved, but the device complexity increases

Engineering Contradiction:

Improvepower factor correctionVSAvoidcircuit configuration

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent merges the power factor correction function with the power conversion function into a single integrated power converter circuit. By combining these functions, the invention eliminates the need for a two-stage configuration (separate power factor correction circuit and power converter) and achieves both functions in one stage, thereby reducing circuit complexity while maintaining power factor correction capability.

Inventive Principle:

Principle #5Merging (Combining)

Data Source

PatentUS10476433B2Microwave generator with power factor correction function and control method thereof

Publication Date: 2019.11.12 DELTA ELECTRONICS INC(CN)

AI summary

A microwave generator includes a power supply, an output circuit, a feedback oscillator, a pulse controller, a signal combination circuit and a semiconductor amplifier. The power supply converts input voltage and input current into output voltage and output current. The output circuit generates a microwave signal to an output terminal of the microwave generator and a feedback signal according to the microwave signal. The feedback oscillator generates an oscillation signal according to the feedback signal. According to a reference signal, the pulse controller generates a pulse signal. According to the oscillation signal and pulse signal, the signal combination circuit generates a control signal. The semiconductor amplifier generates and adjusts an amplified signal according to the control signal. The output circuit generates the microwave signal according to the amplified signal. The output current is adjusted according to the amplified signal. Consequently, the input current and the input voltage are in phase.