Bidirectional DC Solid-State Circuit Breaker With Back-to-Back Switches
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Solution Overview
Problem
Existing DC solid state circuit breakers are unidirectional, providing only one-way protection in DC power systems, which is inadequate for bidirectional current flow applications.
Innovation Solution
A DC solid state circuit breaker design that includes a power electronics section with at least one transistor switch and one or more airgap sections with transistor switches arranged in back-to-back configuration, enabling bidirectional current interruption and fail-safe operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If mechanical DC circuit breakers are used for bidirectional current flow, then bidirectional protection is provided, but switching lifetime and interruption reliability deteriorate at high voltage
Solution Approach 1:
The patent replaces mechanical switching elements with semiconductor switching elements (MOSFETs, IGBTs) to eliminate mechanical wear and improve reliability. The solid state circuit breaker uses transistor switches instead of mechanical contacts, providing bidirectional protection without the switching lifetime limitations of mechanical breakers at high voltage.
Solution Approach 2:
The patent designs a universal solid state circuit breaker that can handle bidirectional current flow by incorporating multiple transistor switches configured to interrupt current in both directions. This multi-functional design allows a single device to provide protection regardless of current direction, replacing the need for direction-specific mechanical breakers.
2Reliability
If solid state circuit breakers are used, then switching lifetime and interruption reliability improve, but bidirectional protection capability is lost
Solution Approach 1:
The patent segments the circuit breaker into multiple functional sections, each with transistor switches dedicated to specific current directions. The first transistor switch handles current in one direction while the second transistor switch handles current in the opposite direction, allowing the solid state device to achieve bidirectional protection through functional segmentation.
Solution Approach 2:
The patent adds the dimension of directional control by incorporating multiple transistor switches that can independently control current interruption in different directions. This transforms a unidirectional solid state breaker into a bidirectional device by operating in multiple dimensional spaces of current flow control.
3Device complexity
If unidirectional solid state circuit breakers are used, then device complexity is reduced, but protection coverage in bidirectional systems is insufficient
Solution Approach 1:
The patent merges multiple unidirectional protection functions into a single bidirectional solid state circuit breaker by combining transistor switches and control logic that can detect and respond to faults in both current directions. This integration provides comprehensive protection coverage while maintaining manageable device complexity through unified design.
Data Source
AI summary
A direct current (DC) solid state circuit breaker includes a first terminal, a second terminal, a power electronics section comprising at least a first transistor switch, and one or more airgap sections that include at least a second transistor switch and a third transistor switch. The second transistor switch and the third transistor switch arranged in back to back configuration such that i) the second transistor switch is configured to interrupt current flowing in a first direction from the first terminal to the second terminal and ii) the third transistor is configured to interrupt current flowing in a second direction from the second terminal to the first side terminal. The DC solid state circuit breaker also includes a controller configured to detect a fault condition and control operation of the power electronics section and the one or more airgap sections in response to detecting the fault condition.