How to choose and use angle sensors for power steering, motors and robotics
The AK7451 employs the tracking servo system architecture to ensure zero latency rotation angle sensing. The zero-latency angle sensor can output up to eight-pole UVW winding phases (Figure 7), which significantly improves its versatility, allowing it to serve a broad array of motor drive and encoder applications. Also, the expansion of the ABZ phase output resolution setting from four types to 16 types enhances motor control usability. It also allows AK7451 angle sensors to facilitate rotor position detection in DC
brushless motor-driven operation without Hall IC installation. Here, it’s worth mentioning that for some position sensing applications, latency is not a critical issue. In electric power steering (EPS) hand wheel angle sensing, for example, a new angle value is requested every millisecond (ms). Also, it’s important to distinguish between errors caused by sensor IC and magnetic input, allowing the angle sensor IC to be used to compensate for the errors related to magnetic input.
Zero latency angle sensors
The AK7451 is a 12-bit angle sensor that detects rotation speed and angles by measuring the intensity of a magnetic field. It features a combination of magnets operating parallel to the IC surface while offering tracking speeds of up to 20,000 rpm. After detecting the magnetic field vector parallel to the IC surface, it outputs the absolute angular position of the magnet, and subsequently, the relative angular position.
Figure 7: AK7451 enables designers to program 16 ABZ output resolution settings and eight UVW output pulse number settings via EEPROM. (Image source: AKM Semiconductor)
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