Submersible Pump Generator Control with Inverter Soft Start

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Solution Overview

Problem

Existing engine-driven electric generators face inefficiencies in fuel consumption and operation control, particularly when powering devices that start and stop based on monitored conditions, leading to excessive fuel use and large engine requirements due to direct-on-line starting and constant high-speed operation.

Innovation Solution

An operation control method for engine-driven electric generators that includes an inverter device to gradually adjust frequency and engine operation based on monitored conditions, such as water level, to optimize power feeding to devices like submersible pumps, reducing fuel consumption and allowing smaller engine use.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Speed

If the engine continues operation at rated rotation speed when the submersible pump is stopped, then the engine can respond quickly when the pump needs to restart, but fuel consumption increases

Engineering Contradiction:

Improveengine response speedVSAvoidfuel consumption

Core Design Contradiction:

SpeedVSUse of energy by moving object

Solution Approach 1:

The engine control unit dynamically adjusts the engine rotation speed based on the operational state of the motor device. When the motor device is stopped, the engine transitions from rated rotation speed to idle rotation speed, optimizing fuel consumption while maintaining readiness for quick restart when needed.

Inventive Principle:

Principle #15Dynamics

2Speed

If direct-on-line starting is used for the submersible pump, then the pump can start immediately, but the engine size must be large to handle the high starting current

Engineering Contradiction:

Improvepump start speedVSAvoidengine size

Core Design Contradiction:

SpeedVSWeight of stationary object

Solution Approach 1:

The inverter device dynamically adjusts the frequency of power supply to the motor device during startup. Instead of direct-on-line starting, the frequency is gradually increased from low to rated frequency, enabling smooth acceleration of the pump while reducing the peak current demand, thus allowing a smaller engine size.

Inventive Principle:

Principle #15Dynamics

3Reliability

If the engine operates at rated rotation speed continuously, then power supply is always available, but fuel consumption increases during idle periods

Engineering Contradiction:

Improvepower supply availabilityVSAvoidfuel consumption

Core Design Contradiction:

ReliabilityVSUse of energy by moving object

Solution Approach 1:

The control system continuously monitors the operational state of the motor device and provides feedback to the engine control unit. When the motor device is stopped, the feedback signal triggers the engine to reduce to idle rotation speed, optimizing fuel consumption while maintaining the ability to quickly restore full power supply when needed.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The engine operation mode is dynamically changed based on real-time operational requirements. The engine control unit switches between rated rotation speed and idle rotation speed modes, ensuring power supply availability when needed while minimizing fuel consumption during idle periods.

Inventive Principle:

Principle #15Dynamics

4Adaptability or versatility

If frequent start and stop operations are performed, then the pump adapts to water level changes, but mechanical stress and wear increase

Engineering Contradiction:

Improvepump adaptation to water levelVSAvoidmechanical durability

Core Design Contradiction:

Adaptability or versatilityVSStrength

Solution Approach 1:

The inverter device enables dynamic speed adjustment of the motor device by varying the frequency of power supply. Instead of frequent start-stop operations, the pump can operate at reduced speeds during partial load conditions, adapting to water level changes while significantly reducing mechanical stress and wear on the pump components.

Inventive Principle:

Principle #15Dynamics

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 method significantly reduces fuel consumption and noise by optimizing engine and frequency control, enabling smaller generator sizes and smoother operation of connected devices, while avoiding frequent starts and stops.

Implementation Method 1

an inverter device (30) that converts an alternating current (AC) input from the electric generator (20) into direct current once

Methodology Applied

Scientific EffectRectification:

Implementation Method 2

and afterwards converts it into alternating current of a predetermined frequency, allowing outputting the alternating current to an external load

Methodology Applied

Scientific EffectInversion:

Data Source

PatentUS12519407B2Operation control method for engine-driven electric generator and engine-driven electric generator for driving a submersible pump for drainage

Publication Date: 2026.01.06 HOKUETSU INDUSTRIES CO LTD

AI summary

To provide an operation control method, in which a state (water level) of a monitored place (water source) is monitored, and when the state of the monitored place satisfies a predetermined start condition in a standby state where the engine of an engine-driven electric generator stops, an engine is started; the inverter device is caused to perform output to gradually increase a frequency from a predetermined low frequency (e.g., 0 Hz) to a predetermined set frequency (e.g., 60 Hz); and the output of a predetermined steady frequency (e.g., 60 Hz) is continued to be performed. Then, when the state of the monitored place satisfies a predetermined stop condition (lower than the lower limit water level), the inverter device is caused to stop an output and the engine is caused to stop to transit to the standby state.