Application of adaptive control in elevator door system

I. Introduction

With the rapid development of the national economy and the increasing number of modern buildings, the elevator has become an indispensable tool in people's daily life. The elevator door system is a typical motor servo system, which is the actuator of the elevator door switch. At present, the elevator door control system is mainly composed of AC motor and speed control system, but also a few by DC motor and speed control system. Although the former is small in size and long in service life, the control is more complex, and the latter is simple in control, but the motor has large size and short brush life. The normal operation of the elevator is related to the personal safety, therefore, the elevator door machine to the motor and its control system are put forward higher requirements. According to statistics, the elevator door switch is not normal operation of the elevator is more likely to occur in the process of failure.

Two, elevator door machine control system of the key technology

In industrial applications, brushless DC motor has obvious advantages in the aspects of rapidity, controllability, reliability, volume weight, economy and so on. In recent years, with the continuous improvement of the performance price ratio of rare earth permanent magnet materials and power electronic devices, the application of Brushless DC motor as high performance speed motor and servo motor in industry is more and more widely.

1, acceleration and deceleration process of the S curve

To achieve a good motor deceleration process of the S curve, can make the door machine system has good operating characteristics, the elevator door switch smoothly, reducing motor by impact load, improve system reliability, prolong the service life of the system.

2, adaptive control system

Elevator door machine control system should be able to meet the different specifications (width), different mechanical characteristics and different working status of the elevator door. And with the increase in the use of time, the same elevator door due to wear, aging and other reasons, its mechanical properties will change. This complex and changeable characteristics, it is difficult to use mathematical models to describe, only with the help of adaptive control strategy, so that the control system to meet the long-term stable and reliable operation of the requirements.

Three, the control strategy of the system

1, acceleration and deceleration process of the S curve

In order to achieve a smooth acceleration and deceleration characteristics, to maximize the reduction of the motor acceleration and deceleration of the elevator door machine system of mechanical shock, the need to reduce the motor when the S curve. The motor deceleration process is divided into three sections, in order to speed up the process as an example, the first section adopts the uniform acceleration method, second using constantacceleration, third with uniform acceleration reduction, and the working curve as shown in figure 1.

Fig. 2 acceleration and deceleration curve

2, adaptive control

The structure of adaptive control system is illustrated. The parameters of the feed forward controller FB and the feedback controller FF are variable, and the difference between the reference model and the actual system response can be adjusted according to the difference between the reference model and the actual system to ensure that the two responses tend to be consistent.

3, control system

A mathematical model for the controlled object of the model is:

The XP, up, YP are the state vector, the control vector and the output vector of the controlled object respectively. Ap, Bp and C are the corresponding dimensions of the matrix.

When the reference model is selected, it is generally made to make it have the same structure as the controlled object, and its parameters can be selected according to the system design requirements. So the reference model can be set as

The XM, YM and RM are the state vector, the output vector and the input vector of the reference model. Bm and Am are the matrix of the desired performance with corresponding dimension.

System generalized output error equation:

In the formula: YM is the output of the model, and YP is the output of the adjustable system.

Generalized state error equation of the system

: XM is the state vector of the model, and the XP is the state vector of the system.

The equation of generalized error motion of the upper form is

According to the working principle of the system, the generalized error between the system and the reference model is the representative of the model reference adaptive control system.

The equivalent error adaptive control solution of epsilon and E as small as possible, i.e.:

Different design methods, such as local optimization and stability design, can be used to meet the corresponding adaptive control laws.

4, the operation curve of the door machine switch

In the normal operation of the elevator door machine, the S curve of the motor acceleration and deceleration will vary with the different parameters of the system. In this paper, the operation of the elevator door machine is divided into 7 S curve plus deceleration process, as shown in figure 4. The speed of different characteristics, so the system adopts adaptive control principle, for each process according to the actual situation of elevator door operation, generating a set of auxiliary velocity values involved in the calculation, to correct the actual S curve and the S curve of the difference between the ideal.

OE: the width of the door, the door machine specifications vary, in 350mm ~ 2400mm between.

EG: the door open and close the stroke, generally 35mm.

O point: the limit point for the open door. The door to A operation, the shutter speed by N6 and then to N7 and maintained, in fact O not only speed, maintain a stall force to open the door.

E point: the limit point for closing. The door to run D, the power supply to the motor according to the system inertial stop at E.

G: open the door to the limit point knife, knife gate open to F when the electrical power system, according to the inertia stop on the spot.

B points: open the door to run, high speed to low speed switching point.

C points: close the door to run, high speed to low speed switching point.

Four, the realization of the system

The door machine control system is composed of a control circuit, a keyboard input and display circuit, a drive and protection circuit and a gate machine switch actuator. The system diagram is shown in Figure 5. Among them, keyboard input and display circuit to complete the man-machine interactive function of elevator door machine implementation process of setting calculation; control circuit according to the signal parameters and the external input, calculation and logic control; and the drive and protection circuit to complete the drive motor and machine system, realize real-time fault detection and protection door system and ensure the safety and reliability of door system.

The elevator door machine adopts rare-earth brushless DC motor servo system controller with MSP430F149 MCU; main circuit adopts IPM power converter circuit, the PWM monopole half modulation control system has the following characteristics.

1, control the motor PWM modulation

PWM usually adopts the half bridge modulation full modulation, namely 6 power tube, only 3 of the pipe in half bridge PWM