“We had the idea for a rotary switch solution back in 2017: we wanted to collaborate across departments to develop an application that is used in all machines and devices – like a power switch, for example. The objective was to find a practical and cost-effective replacement for mechanical switches. This is because the lower a mechanical switch’s protection class, the fewer switching cycles it offers and the shorter its service life. With Rutronik’s concept, these criteria are no longer relevant and, thanks to contactless solutions, are less susceptible to failure in all applications where contamination and vibrations are common,” explains Thomas Kepcija, Product Manager Sensors at Rutronik.
The new application consists of a diametrically magnetized disk magnet and a 3-D hall sensor arranged like an on-axis application. The sensor emits two signals that are shifted by 90 degrees and approximately correspond to a sine and a cosine wave. The angle by which the magnet was rotated is calculated by the arctan2[By/Bx] in the microcontroller, which receives the signals either in digital (SPI/I2C) or in analog form from the sensors. In this demo, the microcontroller converts the angle value into a PWM signal and a gate driver and MOSFETs regulate the power of a hot plate. All of the components used in the demo are from Rutronik’s product range. “The fact that we were able to develop this solution in-house shows that our strategy of offering a 360-degree product mix of all the components required for a project is the right one,” says Markus Balke, Senior Marketing Manager Analog & Sensors, with conviction.
The hot plate, which can be seen in the demo of the rotary switch solution at electronica, represents just one of many possible fields of application. The concept developed by Rutronik is suitable for a wide range of applications including white goods (washing machines, dryers, microwaves), home appliances (ovens, vacuum cleaners, irons), power tools, medical equipment, automotive applications, transport equipment, and industrial machines. Rutronik used sensors from Infineon, Melexis, and TDK, a power supply from Recom, connectors from Amphenol and MPE Garry, MOSFETs and RFID components from ST, antennas from Molex, and at the heart of the application is the RUT2Cloud board with a Renesas Synergy controller and a GSM module from Telit, which also makes it possible to connect the solution to the cloud. Thanks to Rutronik’s platform-based approach, the base concept can be adapted to various projects simply by modifying the software.
This is the main advantage of the solution: the base platform can be used in numerous fields of application – you only need to modify the software. This cuts development costs, results in significant savings due to easy implementation, and, as a result, considerably shortens the time to market thanks to preselecting suitable components. This makes the solution particularly appealing to customers’ project managers, because cost savings are not achieved by comparing component A to component B but due to the reduced amount of storage space required, fewer part numbers, and higher volumes. On top of that, the ability to deploy new features through the cloud connection adds real value. The solution’s wear-free operation due to the absence of mechanical switches also increases product quality, making it suitable for use in harsh environments.