Vehicle ePTO Handshake and DC Bus Pre-Charge for Safe Power Coupling

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Solution Overview

Problem

Existing systems lack coordination between vehicle electrical power networks and auxiliary electrical systems, leading to risks of high inrush currents and operator safety hazards during connection.

Innovation Solution

A method where the auxiliary electrical system transmits an engagement request to the vehicle electrical power network, which then electrically couples the battery to the ePTO point and provides an indication of engagement, allowing the auxiliary system to pre-charge its DC bus and close its contactor safely.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If the contactor is closed to permit power flow to the ePTO point, then the auxiliary electrical system can draw power from the vehicle electrical power network, but high inrush current may flow into the auxiliary electrical system during installation which could damage the system

Engineering Contradiction:

Improvepower delivery to auxiliary systemVSAvoidinrush current damage

Core Design Contradiction:

Use of energy by moving objectVSObject-affected harmful factors

Solution Approach 1:

The vehicle electrical power network performs a pre-charge operation before closing the contactor. A pre-charge resistor is connected to the ePTO point to charge capacitors in the auxiliary electrical system to a predetermined voltage level, thereby preventing high inrush current when the contactor closes and full power connection is established

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

A pre-charge resistor serves as an intermediary element between the vehicle battery and the auxiliary electrical system capacitors. This resistor limits the charging current during the pre-charge phase, protecting the auxiliary system from damaging inrush currents while still enabling power transfer

Inventive Principle:

Principle #24Intermediary (Mediator)

2Power

If the contactor is closed before manual connection is made, then power can flow to the ePTO point, but there is a risk of electric shock to the operator when making the connection

Engineering Contradiction:

Improvepower availability at ePTOVSAvoidoperator electric shock

Core Design Contradiction:

PowerVSObject-affected harmful factors

Solution Approach 1:

The system uses a handshaking communication protocol where the auxiliary electrical system transmits an engagement request to the vehicle electrical power network, and the vehicle network responds with engagement confirmation before the contactor closes. This coordinated feedback mechanism ensures the contactor only closes when both systems are ready, eliminating the risk of operator shock during connection

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The handshaking communication occurs before the contactor closes, allowing both systems to prepare and confirm readiness in advance. This preliminary coordination ensures that the ePTO point is only energized when the auxiliary system is properly connected and ready to receive power, protecting operators from electric shock

Inventive Principle:

Principle #10Preliminary action

3Ease of operation

If manual connection is made without coordination, then the auxiliary system can be connected to the ePTO point, but there is no coordination between vehicle and auxiliary system leading to potential damage

Engineering Contradiction:

Improvemanual connection simplicityVSAvoidsystem coordination

Core Design Contradiction:

Ease of operationVSReliability

Solution Approach 1:

The patent replaces manual mechanical connection procedures with an automated electronic handshaking communication system. The auxiliary electrical system and vehicle electrical power network exchange engagement requests and confirmations through electrical signals, eliminating the need for manual coordination while ensuring reliable system synchronization and protection

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

This solution reduces the risk of inrush currents and enhances operator safety by ensuring controlled power engagement and disengagement between the auxiliary electrical system and the vehicle electrical power network.

Implementation Method 1

pre-charging a DC bus of the auxiliary electrical system

Methodology Applied

Scientific EffectElectrical Resistance: Electrical Resistance

Data Source

PatentUS20250128670A1Method for interfacing an auxiliary electrical system with an electrical power network of a vehicle

Publication Date: 2025.04.24 THERMO KING CORP

AI summary

A method for interfacing an auxiliary electrical system with an electrical power network of a vehicle, the method comprising: i) the auxiliary electrical system transmitting an engagement request to the electrical power network of the vehicle; ii) the electrical power network of the vehicle, responsive to the engagement request transmitted by the auxiliary electrical system, electrically coupling a battery of the electrical power network of the vehicle to an electrical power take-off point of the vehicle and providing an indication to the auxiliary electrical system that electrical power take-off is engaged; iii) the auxiliary electrical system, responsive to the indication that the electrical power take-off is engaged: pre-charging a DC bus of the auxiliary electrical system; and closing a contactor of the auxiliary electrical system to electrically couple the auxiliary electrical system to the electrical power take-off point of the vehicle.