Multi-Input AC Optimizer for PV Power Export

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Solution Overview

Problem

Conventional distributed photovoltaic systems using microinverters or AC optimizers face high costs and low efficiency due to the need for high voltage devices and multiple components, leading to increased expenses and reduced performance.

Innovation Solution

A system comprising multiple DC sources connected to multi-input AC optimizers (MILVACs) with independent maximum power point tracking (MPPT) for each DC source, generating AC voltage and outputting to an AC grid, with the AC outputs connected in series to a system controller, reducing the number of components and connections required.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Power

If microinverters with full grid voltage AC output are used for each PV module, then power conversion is achieved, but high voltage devices and high step-up ratio are required leading to high cost and low efficiency

Engineering Contradiction:

Improvepower conversion capabilityVSAvoiddevice complexity and cost

Core Design Contradiction:

PowerVSDevice complexity

Solution Approach 1:

The system divides the power conversion function into two separate stages: DC/DC conversion at module level and AC conversion at system level. Each PV module connects to a DC/DC converter that performs MPPT and converts DC voltage, while a single central inverter handles AC conversion. This segmentation eliminates the need for each microinverter to handle full grid voltage, reducing device complexity and cost.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent transitions from a distributed microinverter architecture (where each module independently converts to AC) to a hybrid architecture that separates DC/DC and AC conversion functions across different system levels. This dimensional reorganization allows DC/DC converters to operate at lower voltages while the central inverter handles the AC conversion, improving overall efficiency and reducing cost.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

2Power

If AC optimizers with full-bridge inverter are used for each PV module, then DC/AC power conversion is achieved, but multiple components and connections are required increasing expense

Engineering Contradiction:

ImproveDC/AC power conversion capabilityVSAvoidnumber of components and connections

Core Design Contradiction:

PowerVSQuantity of substance

Solution Approach 1:

The patent merges multiple DC/DC converter outputs into a single AC conversion stage. Instead of each PV module having its own full-bridge inverter, the DC/DC converters feed into a shared AC conversion system. This consolidation significantly reduces the total number of components and connections required while maintaining full DC/AC power conversion capability.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The central inverter system serves multiple PV modules simultaneously, performing the AC conversion function for all connected modules through a single device. This multi-functional approach eliminates the need for dedicated AC conversion components at each module level, reducing overall component quantity and system expense.

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Power

If multiple AC optimizers are connected in series to match grid voltage, then power export capability is achieved, but the number of connectors and AC filter size increase leading to higher cost

Engineering Contradiction:

Improvepower export capabilityVSAvoidnumber of connectors and filter size

Core Design Contradiction:

PowerVSDevice complexity

Solution Approach 1:

The patent extracts the AC conversion function from individual module-level devices and consolidates it into a single central inverter. By taking out the AC conversion stage from each DC/DC converter and placing it centrally, the system reduces the number of connectors and AC filters needed, while maintaining the ability to match grid voltage for power export.

Inventive Principle:

Principle #2Taking out (Extraction)

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 results in cost savings and higher efficiency by minimizing the number of connectors and AC filter size, while allowing for a more flexible topology that reduces AC filter size and part costs, enhancing overall system performance.

Implementation Method 1

performing independent maximum power point tracking (MPPT) for each DC source connected to the DC inputs to extract power from each of the DC sources

Methodology Applied

Scientific EffectMaximum Power Point Tracking (MPPT):

Implementation Method 2

converting DC power to low voltage AC power

Methodology Applied

Scientific EffectDC to AC power conversion:

Data Source

PatentUS11515709B2System and device for exporting power, and method of configuring thereof

Publication Date: 2022.11.29 HUAWEI DIGITAL POWER TECH CO LTD

AI summary

System, device and method for exporting power are provided including at least one AC optimizer with plurality of DC inputs each connecting with respective one of plurality of DC sources, and independent maximum power point tracking (MPPT) performed for each respective DC source to extract power from each DC source for output and coupling to AC grid. When multiple AC optimizers are employed, with each AC optimizer having multiple DC inputs, each DC input can be connected to PV module with independent MPPT function. Since, each AC optimizer can serve multiple PV modules, significant cost saving and efficiencies can be achieved. Optionally, on PV sub-module level, each of the multiple DC inputs can be used as an independent MPPT channel for a PV sub-module cell string.