EV Driving Circuit Single Battery Pre-Charging and Emergency Control
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Solution Overview
Problem
Existing electric vehicle driving circuits require a second battery for pre-charging capacitors in inverters, increasing costs and limiting space, and lack emergency control mechanisms when the contactor abnormally operates.
Innovation Solution
A driving circuit with a single battery pack that includes a first contactor, a second contactor in parallel with a current limiting circuit, and a control unit to manage both contactors, allowing for pre-charging and emergency driving by adjusting current supply based on vehicle running information.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a second battery is added for pre-charging capacitors in the inverter, then the pre-charging function is improved, but the device complexity and cost increase
Solution Approach 1:
The patent merges the pre-charging function with the main battery by adding a contactor that can selectively connect the battery to either the motor or the inverter capacitor. This eliminates the need for a separate second battery while maintaining the pre-charging capability, thus reducing device complexity and cost.
Solution Approach 2:
The single battery is designed to perform multiple functions: it can supply power to the motor through the first contactor and pre-charge the inverter capacitor through the second contactor. This multi-functionality replaces the need for dedicated separate power sources for each function.
2Device complexity
If a single battery is used for both pre-charging and motor power supply, then device complexity is reduced, but the ability to perform emergency driving when contactor fails is worsened
Solution Approach 1:
The patent incorporates a backup control mechanism that is activated preliminarily when the main contactor fails. The control unit monitors the status of the main contactor and automatically switches to the backup path through the second contactor and current limiting circuit, ensuring emergency driving capability without requiring a second battery.
Solution Approach 2:
The current limiting circuit acts as an intermediary component that enables the backup path for emergency operation. When the main contactor fails, current flows through the current limiting circuit (which includes resistors) to limit inrush current, allowing the second contactor to safely connect the battery to the inverter for emergency driving.
3Reliability
If current limiting circuit with resistors is added in parallel with contactor, then emergency driving capability is improved, but device complexity increases
Solution Approach 1:
The current limiting circuit is localized specifically in the backup path where it is needed for emergency operation. The resistors are placed only in the parallel branch with the second contactor, limiting their impact to the emergency path while keeping the main operating path simple and efficient.
Data Source
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AI summary
Disclosed is a driving circuit for an electric vehicle having a battery pack and an inverter, and a control method thereof. The driving circuit includes a first contactor connected between a first terminal of the battery pack and a first terminal of a capacitor included in the inverter, a second contactor and a current limiting circuit connected to the first contactor in parallel, and a control unit configured to control operations of the first contactor and the second contactor. The second contactor and the current limiting circuit are connected to each other in series. The current limiting circuit includes at least one resistor, wherein the control unit outputs a first control signal when the first contactor is normally operating and outputs a second control signal when the first contactor is abnormally operating. The first control signal induces the first contactor to turn on, and the second control signal induces the second contactor to turn on.