Design and Development of a Tachometer Using Magnetoelectric Composite as Magnetic Field Sensor

A tachometer was designed and developed using magnetoelectric (ME) composites as the magnetic-field sensor. In the presented design, a simple structure with one permanent magnet and a steel gear was used. Magnetoelectric composites Ni/lead zirconate titanate and metal-glass/lead zirconate titanate were prepared and their sensitivity-field relationship was measured at first. A simulation was conducted to determine the optimal size of the permanent magnet and the dimension of the air gap. According to the magnetic-field distribution in the air gap, the speed sensor was mounted where the ME composites had the highest sensitivity. The practical test results showed that ME composites had much higher and more stable output voltage signal than the coil, especially in the low-speed range. This paper clearly proved the advantage of the ME composites in the application of the tachometer.