Reduce EV range anxiety and improve safety using integrated FOC motor control and advanced sensors
Motor speed can be controlled through PWM, analog, or CLOCK input. Closed-loop speed control is an option, with a programmable revolution per minute (RPM)-to-clock frequency ratio. The sensorless start-up control includes forward and reverse pre-rotation (windmill) detection and synchronization, enabling the A89307KETSR-J to operate over a wide range of motor and load configurations.
Allegro MicroSystems’ Non- Reverse Startup algorithm also improves startup performance. The motor will start in the correct direction after power-up without reverse vibration or shaking. The Soft-On-Soft-Off feature gradually increases the current to the motor with the “on” command (windmill condition), and gradually reduces the current from the motor with the “off” command, further reducing the acoustic noise (Figure 4). The A89307KETSR-J includes an I2C interface for setting the motor rated current, voltage, speed, resistance, and start-up profile. The I2C also implements on/ off and speed control, as well as speed feedback and fault signals.
Sensorless FOC eval board
Designers can use the APEK89307KET-01-T-DK eval board and associated software to speed the development of FOC-based BLDC motor drives using the A89307KETSR-J (Figure 5). This board includes the A89307KETSR-J with access to all input and output pins plus a complete three-phase power stage for driving a BLDC motor. Designers can select FOC drive parameters using a simple graphical user interface (GUI) and load them into the on-chip EEPROM. The minimum BOM needs of the A89307KETSR-J enables the design of drives that fit inside the motor housing, further reducing solution size.
Figure 6: The A31315LOLATR-XY-S- SE-10 3D position sensor can measure rotary motion in the horizontal and vertical planes, and measure linear motion side to side or front to back. (Image source: Allegro MicroSystems)
linear Hall-effect current sensor has a bandwidth of 250 kilohertz (kHz) and is designed for use in motor control, DC-DC converter control, inverter control, and load detection and management. It’s an AEC-Q100 qualified IC and has a response time of <2 microseconds (µs), supporting the rapid overcurrent fault-detection needs of safety-critical applications. 3D position sensing: Contactless linear and rotary 3D magnetic position sensing for throttle, valve, cylinder, and transmission position detection can be quickly implemented using Allegro MicroSystems’ A31315LOLATR-
XY-S-SE-10 3DMAG IC. The device can measure rotary motion in the horizontal and vertical planes, and measure linear motion side to side or front to back (Figure 6). The A31315LOLATR-XY-S-SE-10 sensor provides designers the choice of ratiometric analog, PWM, or SAE J2716 single edge nibble transmission (SENT) output formats. It was developed to meet ISO 26262 ASIL B (single die, in a SOIC-8 package) and ASIL D (redundant dual die, in a TSSOP-14
Sensors for ADAS Designers of xEV systems need to sense current levels in motor drives, DC-DC converters, and inverters, as well as the rotary positions of throttle valves and cylinders, and the speed and direction of the gears in transmissions to implement compact and cost-effective ADAS functions. Allegro MicroSystems offers a variety of sensor solutions for ADAS including: Current sensing: The ACS72981KLRATR-150B3 provides
Figure 5: The APEK89307KET-01-T-DK eval board has the A89307KETSR-J (U1, center left hand side of the board) and six power MOSFETs (right hand side) to drive a BLDC motor. (Image source: Allegro MicroSystems)
Figure 4: The A89307KETSR-J current waveforms for soft “on” (top) and soft “off” (bottom) result in smooth motor operation and reduced acoustic noise. (Image source: Allegro MicroSystems)
package) capability in safety- related automotive systems.
designers with economical and precise AC or DC current sensing. This high-precision
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