Vehicle AC Generator Controller Low-Voltage Protection Circuit

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Solution Overview

Problem

Conventional power generation controllers for vehicle AC power generators face issues with unintentional overvoltage states due to erroneous low-voltage detection, leading to potential failures and unsafe operating conditions.

Innovation Solution

A power generation controller with a low-voltage protection circuit that increases field current to raise power-generation voltage when it falls below a predetermined level, and a low-voltage-protection continuous operation prevention circuit that stops this operation after a predetermined time to prevent overvoltage, ensuring safe operation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a low-voltage protection circuit forcibly supplies field current to raise power-generation voltage when voltage drops below a predetermined level, then the power-generation voltage is maintained, but unintentional overvoltage states occur when low-voltage state is erroneously detected

Engineering Contradiction:

Improvepower-generation voltage maintenanceVSAvoidunintentional overvoltage state

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent applies preliminary action by detecting voltage drops before they cause harmful effects and preemptively activating the low-voltage protection circuit to supply field current, thereby raising the power-generation voltage in advance. This prevents the system from reaching dangerous voltage levels while maintaining reliable operation.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent implements feedback control by continuously monitoring the power-generation voltage and adjusting the field current supply accordingly. When the voltage drops below a predetermined level, the system detects this condition and activates the protection circuit to restore voltage, then deactivates it when voltage returns to normal, preventing overvoltage states through closed-loop control.

Inventive Principle:

Principle #23Feedback

2Stability of the object's composition

If a lowpass filter is provided in the voltage control unit to remove ripple, then the monitored output terminal voltage is smoothed, but the power-generation control cannot cope with instantaneous voltage falls

Engineering Contradiction:

Improveoutput terminal voltage stabilityVSAvoidresponsiveness to voltage changes

Core Design Contradiction:

Stability of the object's compositionVSSpeed

Solution Approach 1:

The patent applies partial action by using the lowpass filter for normal voltage smoothing while implementing a separate rapid-response detection mechanism that operates independently of the filtered signal. This allows the system to maintain stable monitoring under normal conditions while still responding quickly to instantaneous voltage falls when needed.

Inventive Principle:

Principle #16Partial or excessive action

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 solution effectively prevents unintentional voltage rises and overvoltage states, enhancing safety by controlling the power-generation voltage and preventing prolonged low-voltage protection circuit operations.

Implementation Method 1

a low-voltage protection circuit that performs operation of increasing the field current so as to raise the power-generation voltage

Methodology Applied

Scientific EffectElectromagnetic Induction: Electromagnetic Induction

Implementation Method 2

The filter is formed of a lowpass filter for removing a high-frequency ripple

Methodology Applied

Scientific EffectFilter (electronic): Filter (electronic)

Data Source

PatentUS11342870B2Power generation controller for vehicle AC power generator

Publication Date: 2022.05.24 MITSUBISHI ELECTRIC CORP

AI summary

When a state where a power-generation voltage of a vehicle AC power generator is the same as or lower than a predetermined voltage has continued for a predetermined time or longer, a power generation controller stops or disables a low-voltage protection circuit from performing its operation so that an unintentional voltage rise caused by the low-voltage protection circuit is prevented.