TI公司的TIDA-01421是用于无传感器位置测量的汽车有刷马达脉冲计数器参考设计,可配置用于许多DC马达解决方案,具有共模式输入范围宽-14V到80V,工作电压V电池,工作脉冲频率范围100Hz-1.3kHz,马达最大电流+/-16A,和MSP430 LaunchPad开发板接口简单,是高精度测试解决方案.主要用在存储器座椅,电动车窗,侧镜,电梯门和电源箱.本文介绍了TIDA-01421主要特性,框图,和MSP-EXP430FR6989 LaunchPad连接图以及电路图,材料清单和PCB设计图.
The demand to retain memory on the posiTIon of theseat, window, sliding door, mirror, lift-gate, and othersdriven by that motor has increased as small motorswithin the modern automotive vehicle continue toevolve. Existing solutions utilize multiple magneticsensors attached to the body of a motor to provide afeedback loop to the motor control module.
A sensorless approach provides redundancy forexisting solutions and, in some cases, removes therequirement for motors with sensors attached. Thesensorless approach has become increasingly popularthrough the implementation of an in-line, current-sense signal-conditioning circuit. This design provides asolution that is easily modifiable for many automotivemotor systems that control position measurement.
Motor position memory is being applied in more areas of the automotive vehicle including configurationand comfort settings for different driver profiles as well as diagnostics for more efficient and smartercontrol of the motor. The demand for more cost-efficient and easily-configurable solutions for manydifferent motor types has increased. For example, the seats in a vehicle can feature many axes ofmovement and ergonomic adjustment all controlled by individual motors. Existing memory solutions forthese seats require motors with magnetic Hall-effect sensors plus the additional extra wiring for eachsensor. Sensorless position measurement reduces the requirement for this many sensors and wiring bysensing the in-line motor current at the seat control module itself.
A sensorless approach is possible for brushed DC motors due to the effect that the back-electromagneticforce (BEMF) has on the motor current seen entering the motor. As the motor rotates, the impedanceseen by the BEMF periodically changes due to the nature of the DC motor brushes making contact withmultiple poles of the motor and effectively shorting some of the motor windings. This change in impedancechanges the measured current in a very periodic pattern proportional to the actual speed of the motor.
This system provides a way to measure this varying in-line motor current, filter and condition the resultantsignal, then provide a 3.3-V digital logic level series of rising and falling edges for a digital processor tocount and analyze for accuracy and feedback to the main motor controller. With some simple changes incurrent sense resistor values, gain settings, and filter bandwidths, this solution can quickly be modified foruse with many small motor systems.
Configurable for Many DC Motor Solutions
Wide Common Mode Input Range for In-line MotorCurrent Sensing
Operational for Typical 9-V to 18-V Battery Supply
Simple Interfacing With MSP430 LaunchPadDevelopment Kit for Interfacing and Digital Capture
Highly Accurate Test Solution
Lift Gate and Power Trunk
TIDA-01421 Automotive Brushed-Motor Ripple Counter Reference Design for Sensorless Position Measurement Board Image