Electric Vehicle Power Relay Assembly Sparking Prevention
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Solution Overview
Problem
Existing power relay assemblies for electric vehicles face challenges in efficiently supplying and shutting off power while preventing sparking, particularly when charging high voltage batteries, due to the weight and complexity of high voltage relays, leading to reduced fuel efficiency and increased costs.
Innovation Solution
A power relay assembly with a configuration of first and second relays, switching units, and a voltage control module that uses semiconductor switching elements and diodes to manage current flow and prevent sparking, allowing for safe power supply and shutdown during both discharge and charge cycles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a mechanical relay structure with special gas is used to prevent sparks, then sparking is prevented, but weight increases
Solution Approach 1:
The patent replaces the mechanical relay structure with a semiconductor switching element (MOSFET or IGBT). The semiconductor device controls current flow through electronic switching rather than mechanical contact movement, eliminating the need for special gas filling while preventing sparks through controlled switching operation. This substitution resolves the contradiction by maintaining sparking prevention through electronic control while dramatically reducing the weight associated with mechanical relay structures and gas containment.
Solution Approach 2:
The patent changes the operating parameters of the switching element by controlling the gate voltage to regulate current flow. By adjusting the gate voltage parameter, the semiconductor device can smoothly control current onset and cessation, preventing abrupt current changes that cause sparking. This parameter-based control achieves sparking prevention without the weight penalty of mechanical gas-filled relay structures.
2Reliability
If a mechanical relay structure with special gas is used to prevent sparks, then sparking is prevented, but manufacturing cost increases
Solution Approach 1:
The patent replaces the mechanical relay structure with a semiconductor switching element (MOSFET or IGBT). The semiconductor device controls current flow through electronic switching rather than mechanical contact movement, eliminating the need for special gas filling while preventing sparks through controlled switching operation. This substitution resolves the contradiction by maintaining sparking prevention through electronic control while dramatically reducing the weight associated with mechanical relay structures and gas containment.
Solution Approach 2:
The patent employs semiconductor switching elements that are simpler and less expensive to manufacture than mechanical relays requiring special gas filling and sealing. The semiconductor devices can be integrated into standard electronic circuits, eliminating costly specialized components and assembly processes while achieving the same or better performance in spark prevention.
3Ease of operation
If high voltage relay is used to connect and disconnect high voltage/high current, then power control is achieved, but device complexity increases
Solution Approach 1:
The patent merges the functions of multiple peripheral devices and control mechanisms into a single semiconductor switching element. The MOSFET or IGBT integrates current control, voltage regulation, and switching functions that previously required separate mechanical components and control circuits. This consolidation simplifies the overall device structure while maintaining full power control capability for connecting and disconnecting high voltage/high current.
Solution Approach 2:
The semiconductor switching element serves multiple functions simultaneously: it acts as a switch for connecting/disconnecting power, a regulator for controlling current flow, and a protective device for preventing sparks. This multi-functionality eliminates the need for separate specialized components, reducing device complexity while preserving comprehensive power control capabilities.
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 enables efficient power supply and shutdown without sparking, reducing weight and material costs, and improving fuel efficiency by utilizing semiconductor switching elements to limit current flow and prevent arcs, thus addressing the limitations of prior art.
Implementation Method 1
a smart PRA using a semiconductor switching element has been proposed
Implementation Method 2
performs pulse width modulation (PWM) control of the power semiconductor 6 to intermittently flow current
Implementation Method 3
the second switching unit, one end of which is connected to the first switching unit and the other end is connected to the load side one end of the second relay; wherein the first switching unit and the second switching unit respectively include a switching element and a diode connected in parallel with the switching element
Data Source
Figure 1
Figure 2
Figure 3A~3B
AI summary
A power relay assembly for an electric vehicle and a driving method thereof according to an embodiment of the present invention connect the first switching unit and the second switching unit connected in series with each other in parallel with the relay switch, and by allowing the first switching unit and the second switching unit to include semiconductor switching elements and diodes therein, not only when power is supplied from the battery to the load side, but also when charging is performed by supplying a charging current to the battery, it is possible to supply or cut off power while preventing sparks and arcs at the relay contact point. In addition, by using the current characteristics of the semiconductor switching element included in the first switching unit or the second switching unit, the current is limited by adjusting the voltage applied to the semiconductor switching element so that no more than a constant current flows during the pre-charge operation, and thus, it is possible to prevent the rapid current from flowing without installing a separate resistor.