Bidirectional IGBT Protection Circuit for Resettable Overcurrent Blocking
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Solution Overview
Problem
Existing electrical systems in electric vehicles, powered by high-voltage batteries, require frequent replacement of non-resettable fuses like pyro fuses to limit current during faults, which is inefficient and costly.
Innovation Solution
A bidirectional protection circuit utilizing a pair of reverse-blocking IGBTs with a switch control circuit to measure internal currents and send control signals to block current transmission during overcurrent events, minimizing losses and allowing for programmable current thresholds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If non-resettable fuses are used to limit current during faults, then overcurrent protection is provided, but frequent fuse replacement is required which is inefficient and costly
Solution Approach 1:
The patent changes the fundamental parameter of the protection device from a one-time-use fuse to a resettable electronic switch (IGBT). This allows the protection mechanism to be reused indefinitely by simply resetting the gate signal, eliminating the need for physical replacement while maintaining overcurrent protection functionality through programmable current thresholds
Solution Approach 2:
The patent replaces the mechanical/physical fuse element with an electronic switching device (IGBT). Instead of relying on physical melting or breaking of a fuse wire, the system uses electronic control of the IGBT gate terminal to switch the device on and off, enabling resettable operation and eliminating mechanical wear or one-time-use limitations
2Productivity
If bidirectional IGBT switch is used instead of fuse, then fuse replacement is eliminated and programmable current thresholds are enabled, but device complexity increases
Solution Approach 1:
The bidirectional IGBT switch serves multiple functions simultaneously: it acts as a protection device, a controllable switch, and a programmable current limiter. The same device handles both forward and reverse current blocking, eliminates the need for separate fuses, and enables resettable operation, thereby justifying the increased complexity through substantial functional consolidation
Solution Approach 2:
The gate terminal of the IGBT acts as an intermediary control element that mediates between the control circuit and the main current path. By controlling the gate signal, the system can precisely regulate the switching behavior and current thresholds without directly interfering with the high-voltage main circuit, simplifying the control architecture despite the added device complexity
Data Source
AI summary
Circuitry and techniques for providing a bidirectional switch in devices for overcurrent protection and voltage protection are disclosed herein. In one embodiment, a circuit may include a first reverse-blocking insulating gate bipolar transistor (IGBT), having a first gate terminal, first collector terminal and a first emitter terminal. The circuit may include a second reverse-blocking IGBT, having a second gate terminal, a second collector terminal, electrically coupled to the first emitter terminal, and a second emitter terminal, electrically coupled to the first collector terminal. As such the first IGBT and the second IGBT may define a first current path, extending from the first collector to the second emitter; and a switch control circuit, coupled to send a control signal to at least one of: the first gate terminal and the second gate terminal, during an overcurrent event.