Application of AEDB-9340 optical encoder series in servo motor system

introduction

In the servo motor system, the system needs to provide precise position control and speed control, and also requires fast response, high speed, smooth rotation, stable torque, etc. With higher and higher system requirements, the control of the servo motor is becoming more and more complex. The system controller, motor drive, position and speed sensors form a closed-loop control system. For the phase change of the motor, many motors currently use Hall sensors to realize the feedback of the phase change, but the switching accuracy of the Hall sensors is not very high.

AVAGO's industry-leading six-channel commutation optical encoder AEDB-9340 series is designed to easily develop feedback mechanisms in brushless DC motor (BLDC) closed-loop servo systems. This optical encoder integrates channels A, B, and I as position feedback, and uses channels U, V, and W to simulate Hall sensor feedback for rotor commutation. All of these output signals are generated by optical sensors; the number of pole pairs can be simply changed by reconfiguring the code disk style without any hardware modification. This feature helps to significantly save motor manufacturers' design development and product launch time; and the switching accuracy is much higher than that of Hall sensors. This article briefly introduces this series of products.

1. AEDB-9340 Product Introduction

1. Six-channel commutation optical encoder

AEDB-9340 is a transmissive, incremental photoelectric encoder that can provide position feedback signal outputs for three channels: A, B, and I, and motor commutation signals for three channels: U, V, and W. The basic principle of its position sensor is shown in the figure below:

On the left is a code disk with grating intervals, which rotates between the light-emitting tube and the photoelectric detection. The light is transmitted to the light detection on the right through light transmission. After internal processing, it can form the following ABI three-channel position signal output.

While the position signal is output, the related UVW three-way commutation signal can be output according to the single-turn indication signal I. Its output can be directly used as the electronic commutation signal of the brushless motor, as shown in the following figure:

2. Product Features

AEDB-9340 integrates two 90-degree orthogonal outputs of A and B signals, and has a single-turn indication signal I output, which can provide UVW signal output. The output accuracy of A, B, and I channel position information can reach 2500CPR, with a maximum frequency response of 150KHz. The shaft diameter is determined by 3mm arrive 10mm The switching accuracy is also much higher than that of traditional Hall sensors. The commutation accuracy of the AEDB-9340 encoder series is less than ±1 mechanical angle. This integrated solution eliminates the use of brushless DC motor feedback Hall sensors, which not only reduces costs, but also improves the performance of the overall system, while reducing the overall size of the brushless DC motor with integrated feedback devices.

AEDB-9340 can be well applied to printers, plotters, conveyor belts, and factory automation equipment.

2. Application of AEDB-9340 in servo motor

The six-channel commutation optical encoder can realize the output of three channels of position signals A, B, and I in the system, calculate the running speed of the servo motor according to the position, and accurately control the position and speed required by the main controller. At the same time, in the control of servo motors, especially brushless motors, the three commutation signals UVW generated by the photoelectric encoder can be directly used as the commutation signals of the motor without additional signal processing. The encoder has a fast response speed and can adapt to servo motors with various running speeds.

As the industry's demand for encoders to improve motor control continues to increase, motor manufacturers have further promoted the widespread use of optical encoders with integrated steering outputs in the BLDC motor field, and their development momentum has surpassed that of Hall devices. More and more designers are beginning to choose optical encoders in their motor drives. These encoders are cheaper and can achieve the same reliability as Hall sensors, but their accuracy can be higher. In contrast, Hall sensors increase the size of servo motors, design complexity, and assembly costs.

The six-channel commutation optical encoder AEDB-9340 can accurately reflect the position and speed information of the motor in the servo motor application, and can produce the commutation signal UVW of the brushless motor. These commutation signals can directly replace the Hall sensor. The encoder can achieve high-precision and high-speed signal detection. The modular design can also reduce the design size, reduce the design difficulty, and reduce the production cost. For detailed information on this series of products and related technical support, please contact Avago Technologies' authorized agent in Greater China, Shiqiang Telecom .