Inverter Switch Control for DC-AC Conversion Efficiency

Solution Overview

Problem

Existing solar power inverter systems face inefficiencies in converting DC power from solar cells to AC power due to switching losses in the inverter circuit, which limits the overall efficiency of solar power generation systems.

Innovation Solution

The proposed inverter apparatus employs a switch control section that alternately turns ON and OFF multiple switches in series and parallel configurations, along with a smoothing circuit, to convert DC voltage into AC voltage while minimizing switching losses. This apparatus includes a first switch group, a second switch group, and a capacitor, with the switch control section determining optimal switching patterns based on voltage measurements to synchronize the AC output with a reference AC voltage.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of energy

If switches in the inverter circuit are turned ON and OFF to convert DC power to AC power, then power conversion function is achieved, but switching loss increases and conversion efficiency decreases

Engineering Contradiction:

Improveswitching lossVSAvoidconversion efficiency

Core Design Contradiction:

Loss of energyVSProductivity

Solution Approach 1:

The patent applies periodic action by implementing a specific switching sequence where switches are turned ON and OFF in alternating patterns. The control section coordinates the switching of first and second switches in one phase while simultaneously controlling third and fourth switches in another phase, creating a periodic switching pattern that reduces overlapping conduction periods and minimizes switching losses during DC to AC conversion.

Inventive Principle:

Principle #19Periodic action

Solution Approach 2:

The patent implements preliminary action by pre-charging capacitors before switching operations. The control section ensures that capacitors are charged to appropriate voltage levels before the main switching sequence begins, which reduces voltage spikes and switching stress during the conversion process, thereby decreasing switching losses and improving overall conversion efficiency.

Inventive Principle:

Principle #10Preliminary action

2Power

If multiple switches are used in series and parallel configurations for power conversion, then conversion capability is improved, but device complexity increases

Engineering Contradiction:

Improvepower conversion capabilityVSAvoidcircuit complexity

Core Design Contradiction:

PowerVSDevice complexity

Solution Approach 1:

The patent applies segmentation by dividing the inverter circuit into multiple independent switch groups and phases. Each phase has its own set of switches (first and second switches in one phase, third and fourth switches in another phase) that can be controlled independently. This segmentation allows the circuit to handle higher power levels while maintaining manageable complexity through modular control of each segment.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent implements multi-functionality by designing the switch network to perform multiple functions simultaneously. The same switch arrangement handles both power conversion and voltage regulation, while the capacitors serve both as energy storage elements and as part of the switching network. This universal design reduces the need for separate components, thereby reducing overall device complexity despite the high power conversion capability.

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Speed

If switching frequency is increased to improve response speed, then conversion response is improved, but switching loss and heat generation increase

Engineering Contradiction:

Improveconversion response speedVSAvoidswitching loss and heat generation

Core Design Contradiction:

SpeedVSLoss of energy

Solution Approach 1:

The patent applies periodic action by implementing a specific switching sequence where switches are turned ON and OFF in alternating patterns. The control section coordinates the switching of first and second switches in one phase while simultaneously controlling third and fourth switches in another phase, creating a periodic switching pattern that reduces overlapping conduction periods and minimizes switching losses during DC to AC conversion.

Inventive Principle:

Principle #19Periodic action

Solution Approach 2:

The patent implements preliminary action by pre-charging capacitors before switching operations. The control section ensures that capacitors are charged to appropriate voltage levels before the main switching sequence begins, which reduces voltage spikes and switching stress during the conversion process, thereby decreasing switching losses and improving overall conversion efficiency.

Inventive Principle:

Principle #10Preliminary action

Data Source

PatentEP2665174B1Inverter apparatus and solar power generation system

Publication Date: 2021.06.02 OMRON CORP

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Figure 2A
Figure 2B

AI summary

An inverter apparatus comprising a first switch group that is connected to a DC power source and includes a first switch and a second switch connected in series; a capacitor that has one end thereof connected to a first connection point between the first switch and the second switch; a second switch group that is connected in parallel with the capacitor and includes a third switch and a fourth switch that are connected in series; a switch control section that controls an ON/OFF state of the first switch, the second switch, the third switch, and the fourth switch to convert DC voltage from the DC power source into AC voltage and output the AC voltage from a second connection point between the third switch and the fourth switch; and a smoothing circuit that is connected to the second connection point and normalizes a pulse waveform of the AC voltage.