In the existing front-end double wiper system, the synchronization between the left and right wipers is achieved by a mechanical connection (Figure 1). This is necessary because the windshield is affected by the different conditions of dirt, wind and wipers, making the left and right wipers different.
For many years, the automotive industry has been looking for an intelligent solution that can reduce noise and mechanical connection space requirements.
One solution is to replace mechanical connections with electronic solutions (Figure 2). In this architecture, each wiper is driven by a DC motor. The DC motor is controlled by a microcontroller and drive IC that can be installed directly inside the motor assembly. An interface is used to deal with the synchronization of the left and right wipers, so that there is no need to use the mechanical connection of the traditional wiper system between the two wipers, the noise is greatly reduced, and space is also saved.
For cost reasons, the wiper system uses a DC motor. A full H-bridge gate driver that supports PWM and four power MOSFET control directions can control this type of motor. The IC for this application must be designed with a high-voltage process and must be suitable for use in harsh environments. In addition, high-capacity DC motor applications such as windshield wiper systems should use optimized communication interfaces.
Because wiper electronic products are usually very close to car radio equipment, EMC emission must be controlled, and the electronic interruption of car radios will make car drivers unbearable. Differential serial communication interface (SCI) transceivers can be used to reduce this type of radiation and improve EMC performance. The SCI transceiver is a differential device. For systems with only one wiper, it can work in single-ended mode. The SCI function of this gate driver makes it very similar to LIN devices. However, compared to the standard LIN interface, the data transfer rate is faster, up to 100 kbaud.
Each wiper module (Figure 3) consists of a microcontroller, a highly integrated gate driver and a DC motor. Multiple Hall sensors measure the position of the two wipers. The driver sends commands to the microcontroller through the wiper switch. Electronic equipment is installed close to the wiper motor, and the space requirement is not very large.
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