Research On Microchip Control System To VVVF Elevator Based On Serial Communication

The design and realization about hardware of microchip control system to VVVF elevator, the pivotal algorithmic of the software, and the design and analysis about the algorithmic structure of Elevator Group Control System (EGCS), composed the central content of this thesis. To design the control system of elevator in distributed structure, different MCU were used to construct different controllers in this system. The 16-bit MCU MB90F543 from FUJITSU SEMICONDUCTOR was the core of the Main Controller, and the 8-bit MCU 89C53RC from STC SEMICONDUCTOR was used to design the Car Controller and Hall Controller. All controllers in this system communicated each other by serial communication technology. To low cost and increase reliability this control system replaced PLC to control elevator. And CAN field bus technology was used to build the EGCS by linear network, which was more economical and efficiently.Based on the function demand of elevator control system, the circuits and hardware of all controllers were designed in this paper. Main Controller was one of the system controllers and had many function circuits. They included digital-signal-collection circuit, analog-voltage-signal-collection circuit, UART circuit, EGCS interface circuit, high voltage detecting circuit, timer controlling circuit, operating and displaying circuit, and so on.Depended on the distributed structure, the tasks of every controller in control system were assigned to work. According to the tasks the software programs were designed. Because the elevator control system was a high real-time control system, the elevator control programs were designed according to algorithmic that was composed by Minimum Time-slice Round-robin scheduling and Priority-task Interrupt scheduling. The Main Controller used the 16-bit reloaded timer to make the time-slice run. The digital output from Main Controller made inverter change output frequency, which could adjust the speed of elevator accurately. This paper presented the program flows, which included elevator inspection traveling flow, elevator self-tuning traveling flow and full-selective traveling flow. To answer hall-call obeyed to a principle during the full-selective traveling. The principle was"closer at same direction, far at different direction". The control system which could meet all requests of elevator controllers had already passed the project test. In the fast developing society, the busy office-buildings had big need of elevator. Even two elevators were not enough to meet the need. So how to make more than two elevators work concordantly was an exigent problem to research. As a high-quality control system, it was necessary to research deeply into EGCS (Elevator Group Control system). Based on the linear network structure of the CAN (Control Area Network) bus, this paper proposed an elevator group control structure that was different from elevator group centralized control structure that was often used. This structure could make some elevators connect to be an elevator group control system without any added devices. It was economical and convenient to realize. According to the linear network structure of the CAN bus, this paper proposed and designed a multi-objective elevator group control algorithm based on the time-stage & experience traffic-flow. The thesis also stated how to analyze and deduce the multi-objective elevator group control algorithm. Finally the thesis analyzed the operating process of this EGCS and CAN bus linear network. The result of analysis indicated that this algorithm can work effectively and rapidly, and alleviate the burden of the elevator group control network.