Dual-Stage Vehicle Protection System for Contact Voltage Safety
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing vehicle protection systems for ungrounded frames with traction drives and current collectors face challenges in providing adequate safety against dangerous contact voltages, especially in varying operating states, and are costly to implement, particularly in diesel-electric hybrid vehicles with complex mechanical drive trains.
Innovation Solution
A dual-stage protection system with a first stage using an electrically isolating DC-DC converter and a second stage of single-insulated mounting, switchable based on vehicle operating states, allowing for adaptive safety measures depending on interactions between persons and the vehicle, with automated switching and monitoring for insulation faults.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If double insulation is implemented continuously to prevent dangerous contact voltages, then safety against contact voltages is improved, but device complexity and cost increase
Solution Approach 1:
The protection system dynamically switches between double insulation mode (when DC-DC converter is operational) and single insulation mode (when DC-DC converter is bypassed), adapting the insulation level to the current operating state of the vehicle rather than maintaining continuous double insulation
Solution Approach 2:
The system changes the insulation parameter (from double to single) based on the operational state of the DC-DC converter, allowing the protection level to be adjusted according to whether the converter is actively isolating the traction drive from the contact line
2Reliability
If double insulation is implemented continuously to prevent dangerous contact voltages, then safety against contact voltages is improved, but manufacturing cost increases
Solution Approach 1:
The protection system dynamically switches between double insulation mode (when DC-DC converter is operational) and single insulation mode (when DC-DC converter is bypassed), adapting the insulation level to the current operating state of the vehicle rather than maintaining continuous double insulation
Solution Approach 2:
The system changes the insulation parameter (from double to single) based on the operational state of the DC-DC converter, allowing the protection level to be adjusted according to whether the converter is actively isolating the traction drive from the contact line
3Reliability
If DC-DC converter is used for electrical isolation, then safety is improved in low-speed operation, but device complexity increases
Solution Approach 1:
The DC-DC converter serves multiple functions: it provides electrical isolation for safety during low-speed operation with the current collector raised, and can be bypassed during high-speed operation, reducing its operational burden and allowing a simpler converter design
Solution Approach 2:
The protection system dynamically switches between double insulation mode (when DC-DC converter is operational) and single insulation mode (when DC-DC converter is bypassed), adapting the insulation level to the current operating state of the vehicle
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 dual-stage protection system ensures safe operation by providing appropriate levels of electrical safety in different vehicle states, reducing costs and complexity compared to full double-insulation, while maintaining safety during all operating conditions.
Implementation Method 1
an electrically isolating DC-DC converter which is connected between current collector and traction drive
Implementation Method 2
The protection system must electrically isolate the vehicle frame and vehicle body from the traction drive and current collector
Data Source
AI summary
A vehicle has an electric or hybrid-electric traction drive supported by an ungrounded vehicle frame. The vehicle also has a current collector, which can be electrically connected to the traction drive and which can be brought in galvanic contact with a contact line of a grounded contact-line system to supply traction energy. The vehicle contains an electrical protection system for avoiding dangerous contact voltages on the vehicle frame or on a vehicle part connected to the vehicle frame in a conductive manner. The protection system has a first protection stage, a second protection stage, and a switching element, by which the protection system can be switched between the first and the second protection stages. The first protection stage provides greater safety from dangerous contact voltages than the second protection stage. Thus, a protection system can be provided which provides sufficient safety in all operating states of the vehicle.