Various sensors and LSIs, mainly motor related products by Asahi Kasei Microdevices, (AKM), are used in industrial machines that realize factory automation. AKM has the largest market share in magnetic sensor market.
The market needs for sensors and LSIs are increasing due to trends of factory robotization and Industry 4.0.
A core-less current sensor has been developed based on AKM’s experience of over thirty years in magnetic sensor. It is housed in an ultra small package with dielectric strength, ideal for drive current detection up to 35A for motors and power conditioners.
A current detection solution with a shunt resistor needs insulation between the primary side and the secondary side by using an insulating element such as optocoupler that is large and expensive. Current flows in the shunt resistor also generates heat.
AKM’s small magnetic current sensor can shrink the board size since the output signal can be transmitted to an A/D converter directly. It reduces heat generation in current detection since it does not use a resistor.
A digital output reference module of current sensor, that is suitable for AC Servos, Robots and General Inverters, is available.
High accurate rotation angle detection can be accomplished by combining a bias magnet with AKM’s semiconductor magnetoresistive element, (SMRE). A high resolution pseudo absolute encoder, (over 20-bit), is available by applying electrical interpolation to gear teeth while measuring Z-axis phase. An absolute encoder can be configured by using phase difference of the main scale and sub scale gear wheels to calculate absolute angle. Those encoders are easily installed to hollow structures suitable for hollow servo motors of machine tools and robots.
Magnetic encoders are used for spindle motors of machine tools in the factory since they are environmentally resistive such as dust, dirt and oil. AKM’s SMRE have good temperature characteristics and very small variability among individual devices. It can archive more than 20-bit accuracy in rotation angle detection by interpolation.
An SMRE detects magnetic density generated between a bias magnet and a magnetic gear wheel. The angle detection method uses a phenomenon that the SMRE output signal will be an exact one cycle sine or cosine wave for each gear tooth rotation. The electric angle of a single gear tooth is calculated from arc tangent by converting this SMRE output to a digital signal by AKM’s ZDS-ADC without delay. Therefore the angle detection resolution can be increased as high as the number of gear teeth, enabling high resolution and high accuracy thin servo motors.
A non-contact absolute rotary encoder can be easily designed with AKM’s magnetic rotation angle sensor, the AK7451, and a diametrically magnetized two-pole magnet. Low power, low heat generating, and a low vibration small motor can be designed by optimizing the motor drive current according to rotation position information detected by the rotary encoder. In addition, AKM’s magnetic rotation angle sensor helps to increase motor efficiency of stepping motors and brushless DC motors with AKM’s motor drivers due to advantages in low-noise operation and high accuracy current control.
Magnetic encoders have features such as long life, high temperature resistance and environmental resistance to dirt, dust and oil. In addition, with AKM’s original technology that only detects the horizontal vector of the magnetic field, the AK7451 achieves great tolerance to axial alignment mismatch. The azimuth error can be suppressed to less than 0.2 degree against 0.5mm, (max), orthogonal misalignment between the center of the sensor and the magnet rotation center. (*) The AK7451 is able to support high speed rotation of a motor since it is able to track the output signal with only 1.8μs of delay time.
(*) with Φ10mm×t2mm 2-pole radially magnetized Neodymium magnet
An evaluation kit for magnetic rotary encoder is available, enabling simple evaluation by just connecting a motor. ABZ/UVW output can be monitored. A magnet, a magnet holder, installation jigs, a board with IC, and a cable are included in this evaluation kit. Absolute angle can be read by 4-wire SPI communication. It can be used as a absolute encoder. In addition, a programing board that enables a USB connection with a PC is available. Rotation angle readout and memory write/read can be made with a dedicated software.
Normally, SAR A/D converters are used in a system that needs real time response for motor control encoders. However, it is not easy to construct a system or improve characteristics with an SAR A/D converter since its acquisition time becomes shorter and the input capacitance becomes larger when seeking high speed and high accuracy performance.
Zero Latency Delta Sigma, (ZDS), ADCs: AK9232/AK9233/AK9234 are new concept A/D converters that have both SAR’s high accuracy and Delta Sigma’s high linearity.
An 18-bit, 1.1MHz 2ch ADC: the AK9232, realizes low input capacity and long acquisition time while maintaining high speed and high accuracy. It is housed in a 4mm x 4mm package, the smallest class in the world, shrinking system construction and improving characteristics.
16-bit and 14-bit versions of the AK9232, the AK9233 and the AK9234, are also line upped.
Longer acquisition time and lower input capacitance are accomplished with the ZDS architecture that is developed from many years’ experience from AKM in Mixed-signal LSI technologies, comparing to a general SAR ADC. The ZDS architecture reduces ADC amplifier load. The AK9232/3/4 contributes to improving accuracy and speed of your system.
Offset/Gain/Phase adjustments for converted signal are available on each channel independently.
The AK9232/3/4 is capable to output the polar coordinate, (angle, “θ”, moving radius, “r”), when the cosine wave and sine wave are input to the CH0 and the CH1, respectively, from the result of simultaneous conversion of the input signal of the CH0 and the CH1.
|CQ-330x series||The open loop type Coreless Current Sensors|
|CQ-320x series||Ultra-small Coreless Current Sensors|
|CZ-381x series||Ultra-high Accuracy Coreless Current Sensors|
|MS series||Semiconductor Magnetoresistive Elements (SMRE)|
|AK7451||ABZ/UVW phase adjustable 12-bit Rotary Angle Sensor|
|AK9223MK||2-channel 1-bit 10MHz ΔΣ modulator|
|AK9232||Dual 18-Bit 1.1MSPS ZDS A/D Converter|
|AK9242||AFE with Dual 16-Bit 1.1MSPS ZDS A/D Converter|