Optimization Design of Contactor Driver for Electric Vehicle

The control system of new energy electric vehicles generally uses low-voltage batteries for power supply, including contactors that control the on-off of power lines. For this reason, contactors in cars are usually driven step up-down converters. This article compares and analyzes the driving schemes between constant-type current, stepped-type current, and curved-type current by modeling and simulating the electromagnetic mechanism of the contactor. The simulation results show that the contactor driven by the curve current has better dynamic characteristics. A prototype of contactor driver with
$9\sim 18\mathrm{V}$
input was constructed based on the buck-boost converter. The experimental results showed that compared with the traditional constant-type current or voltage drive scheme, the curved-type current scheme reduced the number of bounces by 67%, the bounce time by 60%, and the closing time was only extended by 2ms. At the same time, the contactor holding power consumption was only 8.3% of the original, effectively optimizing the working performance of the contactor.