Direct DC-Fed VFD for Solar AC Motor Drive Efficiency

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Solution Overview

Problem

The need to replace simple well head gas engines with cost-effective alternatives due to changing regulations, particularly in the oil field industry, and the inefficiencies and increased costs associated with using electric powered motors and AC inverters.

Innovation Solution

A solar battery powered variable frequency drive system that directly connects a high voltage battery bank to the DC terminals of a VFD, eliminating the need for AC inverters and allowing direct conversion of DC power to AC power for AC motors, thereby increasing efficiency and reducing installed costs.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If AC inverters are used to convert DC power to AC power for motors, then the system can operate AC motors with DC power sources, but the system efficiency decreases and installed cost increases

Engineering Contradiction:

Improvesystem efficiencyVSAvoidnumber of inverter components

Core Design Contradiction:

Use of energy by moving objectVSDevice complexity

Solution Approach 1:

The patent removes the AC inverter component from the system by directly connecting the DC battery bank to the DC terminals of the VFD. This extraction of the unnecessary inverter component eliminates energy losses and reduces system complexity while maintaining the ability to power AC motors.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent merges the DC power source connection directly with the VFD DC terminals, eliminating the intermediate AC inverter stage. This direct connection integrates the power flow path, reducing component count and improving overall system efficiency.

Inventive Principle:

Principle #5Merging (Combining)

2Ease of operation

If overhead cable or underground cable is used to bring power to remote locations, then AC motors can be powered, but the installed cost increases

Engineering Contradiction:

Improvemotor operation capabilityVSAvoidinstalled cost

Core Design Contradiction:

Ease of operationVSEase of manufacture

Solution Approach 1:

The system generates its own power locally using solar panels and battery storage, eliminating the need for external power infrastructure such as overhead or underground cables. This self-service approach reduces installed costs while maintaining motor operation capability.

Inventive Principle:

Principle #25Self-service

3Adaptability or versatility

If simple well head gas engines are used, then the system is simple to operate, but the system fails to meet changing emission regulations

Engineering Contradiction:

Improveregulation complianceVSAvoidsystem complexity

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent replaces the mechanical combustion-based gas engine with an electric motor driven by solar panels and battery storage. This substitution eliminates emission problems while providing the necessary pumping capability, adapting to emission regulations without excessive complexity.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

4Speed

If reciprocating engines are used, then the system can operate at low speeds, but the system fails to meet CARB emission regulations

Engineering Contradiction:

Improvemotor speedVSAvoidregulation compliance

Core Design Contradiction:

SpeedVSAdaptability or versatility

Solution Approach 1:

The patent replaces emission-producing reciprocating engines with electric motors that can precisely control speed through the VFD. This substitution maintains the ability to operate at low speeds required for pump jack applications while achieving compliance with CARB emission regulations.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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

The system achieves higher efficiency and reduced costs by eliminating AC inverters, allowing for more efficient motor operation and increased reliability with fewer components, suitable for various applications including oil field operations and water supply systems.

Implementation Method 1

A solar panel array is connected in series with a high voltage battery bank through a charge controller

Methodology Applied

Scientific EffectPhotovoltaic effect: Photovoltaic Effect

Implementation Method 2

The high voltage battery bank is connected directly to DC terminals of a variable frequency drive

Methodology Applied

Scientific EffectBattery electrochemical conversion: Battery (electricity)

Implementation Method 3

The illustrated embodiment converts DC power from the solar panel array or high voltage battery bank to variable frequency AC power suitable for an AC motor

Methodology Applied

Scientific EffectElectrical energy conversion:

Data Source

PatentUS12500539B2Solar A/C direct motor drive

Publication Date: 2025.12.16 TOMLINSON JAMES

AI summary

An electrical device comprising: a high voltage DC power storage system; a variable frequency drive comprising DC terminals, a variable frequency inverter, and a variable drive output, wherein said high voltage DC power source is direct fed to said DC terminals; and an AC motor connected to said variable drive output.