Battery-Inverter Semiconductor Switch for Inrush Current Protection
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Solution Overview
Problem
Mechanical contact type relays in motor-driven vehicles, such as hybrid or electric cars, take milliseconds to switch and can cause large currents that may break the inverter circuit, necessitating the use of additional components like fuses to prevent damage, increasing complexity.
Innovation Solution
A semiconductor unit with a transistor and controller configuration, where the transistor is arranged between the battery and inverter circuit, and a resistor is used to control the transistor's activation state based on current thresholds, allowing it to deactivate quickly and prevent excessive current from reaching the inverter circuit, eliminating the need for a fuse.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a mechanical contact type relay is used to control current flow between the battery and inverter circuit, then the relay can effectively switch the circuit, but the relay takes milliseconds to switch and may cause large currents that break the inverter circuit
Solution Approach 1:
The patent replaces the mechanical contact type relay with a semiconductor transistor (IGBT or MOSFET) that is controlled by a controller. The transistor switches in microseconds rather than milliseconds, and the controller deactivates the transistor when current exceeds a threshold value, thereby protecting the inverter circuit without requiring additional fuses or complex mechanical relay arrangements.
Solution Approach 2:
The patent changes the switching speed parameter from milliseconds (mechanical relay) to microseconds (semiconductor transistor). This parameter change enables the transistor to respond much faster to current conditions, allowing it to prevent inverter circuit breakage without requiring the additional protective components that would be needed with slower mechanical relays.
2Reliability
If a fuse is arranged in addition to the mechanical contact type relay to prevent inverter circuit breakage, then the inverter circuit is protected from large currents, but the number of components increases
Solution Approach 1:
The patent replaces the fuse (a passive protective component) with an actively controlled semiconductor transistor system. The transistor, controlled by the controller, can dynamically respond to current conditions and deactivate when needed, providing protection without requiring a fuse. This substitution eliminates the need for the additional protective component while maintaining or improving protection effectiveness.
Solution Approach 2:
The transistor system provides its own protective function through controller management. When the current exceeds a threshold, the controller deactivates the transistor, and the transistor itself blocks the excessive current. This self-service capability eliminates the need for separate protective components like fuses, as the transistor system protects itself and the inverter circuit.
3Speed
If a mechanical contact type relay is used for pre-charging, then the relay can control the pre-charging circuit, but the mechanical relay takes milliseconds to switch which is too slow for protecting against inrush current
Solution Approach 1:
The patent replaces the mechanical contact type relay in the pre-charging circuit with a semiconductor transistor controlled by the controller. The transistor switches in microseconds, providing the high speed needed to protect against inrush current while maintaining reliable control of the pre-charging function. This substitution simultaneously improves both switching speed and protection reliability.
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 semiconductor unit effectively prevents inverter circuit breakage by quickly deactivating the transistor when high currents are detected, reducing the need for additional components like fuses and enhancing reliability.
Implementation Method 1
the transistor is deactivated. It takes the transistor a few microseconds to switch from an activation state to a deactivation state
Implementation Method 2
The resistor has a resistance value that is greater than or equal to 100Ω
Data Source
AI summary
A semiconductor unit includes a semiconductor device, a controller, and a resistor. The semiconductor device includes a transistor arranged between a positive electrode of a battery and an inverter circuit electrically connected to the battery. The controller is connected to a control terminal of the transistor and configured to control the transistor. The resistor arranged between the control terminal and the controller. The controller controls the transistor so that when a current flowing to the transistor is greater than or equal to a threshold value, the transistor is deactivated. The resistor has a resistance value that is greater than or equal to 100 Ω.