EV Over-Voltage Protection Circuit With Fuse-Triggered Bus Shutdown
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Solution Overview
Problem
Electric vehicles (EVs) face the risk of electrical component damage due to high voltage levels exceeding a target voltage window, which can lead to safety and cost issues.
Innovation Solution
An over-voltage protection circuit comprising a fuse, trigger circuit, energy-harvesting circuit, driver circuit, gate-hold circuit, and a short-circuit path is implemented. This circuit activates a short-circuit path when the high-voltage bus exceeds a threshold voltage, causing a current surge that exceeds the fuse's current rating, thereby disconnecting batteries from the high-voltage bus.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the voltage of the electrical energy is higher than a target voltage window, then the electrical components of the EV may become damaged, but implementing protection circuits increases device complexity
Solution Approach 1:
The protection circuit is divided into distinct functional modules: a trigger circuit that detects over-voltage conditions, a driver circuit that processes the trigger signal, and a short-circuit path that executes the protection action. This segmentation allows each module to perform its specific function independently, making the overall system more manageable and less complex while maintaining effective protection.
Solution Approach 2:
The trigger circuit acts as an intermediary between the high-voltage bus and the driver circuit. It monitors the voltage level and only activates the protection mechanism when the voltage exceeds the threshold, thereby mediating between the normal operation state and the protection state without requiring constant intervention from the main control system.
2Reliability
If a protection circuit is implemented to detect and respond to over-voltage conditions, then component safety is improved, but the response time and circuit activation delay increase
Solution Approach 1:
The trigger circuit is pre-configured with a Zener diode set to the target voltage window threshold. This preliminary setup allows the circuit to immediately detect and respond to over-voltage conditions without requiring complex real-time calculations or control decisions, thereby minimizing response time while maintaining safety.
Solution Approach 2:
The protection mechanism replaces complex electronic control and decision-making systems with a simpler electrophysical mechanism. The Zener diode's breakdown voltage characteristic provides an automatic, instantaneous response to over-voltage conditions, eliminating the need for software-based detection and control algorithms that would introduce delays.
3Measurement precision
If the trigger circuit uses a Zener diode to detect threshold voltage, then measurement precision is improved, but the energy consumption and heat generation increase
Solution Approach 1:
The Zener diode is selected with a breakdown voltage parameter that precisely matches the target voltage window threshold. By changing the voltage parameter of the detection component to exactly match the required threshold, the circuit achieves high measurement precision without requiring additional calibration circuits or complex reference voltage generation, thereby minimizing energy consumption.
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 damage to EV electrical components by disconnecting batteries from the high-voltage bus when over-voltage conditions are detected, ensuring safety and reducing repair costs.
Implementation Method 1
the trigger circuit includes a Zener diode having a cathode electrically connected to the high-voltage bus and an anode electrically connected to the driver circuit, the Zener diode configured to transition from the non-conducting state to the conducting state at the threshold voltage such that a current flows through a reverse-biased Zener diode
Implementation Method 2
one or more transistors in the driver circuit is/are activated to charge a buffer capacitor in the gate-hold circuit, the buffer capacitor producing a buffer-capacitor voltage that is higher than a threshold voltage of the short-circuit path
Implementation Method 3
the short-circuit path in the second state causing a current through the high-voltage bus to increase above a current rating of the fuse to electrically disconnect the one or more batteries from the high-voltage bus
Data Source
AI summary
An over-voltage protection circuit is electrically connected to one or more batteries and to a high-voltage bus to power the electrical components of an electric vehicle. The over-voltage protection circuit is configured to produce a short-circuit path for current flowing through the high-voltage bus when the voltage across the high-voltage bus is higher than a threshold voltage. The short-circuit path significantly increases the current flowing through the high-voltage bus, which causes one or more fuses to interrupt current flow. The over-voltage protection circuit includes an energy-harvesting circuit that down-converts the voltage across the high-voltage bus to a lower voltage that can power one or more electrical components of the over-voltage protection circuit.