Micro-logic controller not only can be programmed and controlled, but also covers some functions of traditional relay. From the application level, Micro-Logic controller fills the gap between traditional relay and PLC. Taking the electric control of electric hoist as an example, this paper introduces the simplicity and intelligence of microcontroller in comparison with traditional relay control, and looks forward to its advantages and prospects in electric hoist control in the future. Traditional relays and contactors play an important role in the development of electric control system of electric hoist.
Traditional relays and contactors are usually used in electric hoist control.
In the face of these various types of electrical components with uneven quality, unavoidable problems such as large size, complicated wiring, unstable performance, complex debugging and testing equipment will be encountered during installation and debugging, which will result in the decline and adjustment of production schedule. Experiments and maintenance costs increase [2]. During the past 10-20 years, with the rapid development of China’s electric hoist industry, and the improvement of the types and quality of related electrical products, while ensuring the safe and reliable operation of electric hoist, customers put forward higher requirements for simplicity in the operation process and intelligence in the execution of operation options. In the face of the cost of life, a more rapid, flexible and economical control solution appears, which is particularly timely and precious [1]. The electric control of electric hoist adopts microcontroller as the core of the control system, and uses the programmable function of the controller, thermostatic element which not only realizes the advanced concept of safety protection and optimal operation in the use of electric hoist, but also makes the structure of the control circuit concise and clear and easy to understand. The following is a brief introduction of its application in the control system of electric hoist. Since the advent of microcontrollers, many companies in the market have launched their own brands of controllers. And now it has developed into a modular, serialized standard product. It integrates 8 basic logic functions such as “and”, “non”, “or” and special functions such as time timing, counter and analog processing. By replacing the external wiring scheme of traditional relay switch with internal function block programming, in a small module, users can arbitrarily call various functional blocks to construct their own application program, thus realizing the control that used to require many timers, relays and contactors to achieve.
Tasks, eliminating a variety of low-voltage components in the equipment control cabinet, not only saves the cost of components, but also saves the cabinet space. Compared with the traditional relay scheme, the solution of MCU has the advantages of fewer wiring connections, shorter production cycle, smaller control cabinet space and simple maintenance. Because the controller not only covers some functions of traditional relay, but also has programmable control function, to some extent, we can visually understand it as “intelligent relay”. When using standard PLC, it is necessary to carry computer and other ancillary equipment for field programming or debugging. In contrast, the controller can be equipped with an operation keyboard and a display panel. The user can directly program and debug the controller. The display panel can directly display and modify the time, user-defined information and variable parameters. It can also monitor the operation status of the input and output points of the system, thus greatly shortening the programming of the whole system. Debugging time and cost. Moreover, the relay output points of many controllers in the market have 10A or even greater current carrying capacity, good output load capacity, and some can directly connect various actuators, such as small motors, lighting equipment and so on. The electric control system of electric hoist takes microcontroller as its control core, 48V safe low voltage control, contactor and intermediate relay as its actuator; circuit breaker protects the motor from short circuit and overload, and microcontroller protects the control circuit from short circuit; by using the flexible programming function of the controller, combined with electric hoist control and protection, the electric hoist will be protected by short circuit and overload protection. These protections are converted into controller control programs. – T013: Control transformer, providing a variety of voltage input interfaces.
The protection function microcontroller can realize multiple protection functions in the electric control system of electric hoist. These are the guarantee of more safe and stable operation of electric hoist. Taking the protection function of “hoist motor brake monitoring” as an example, the superiority of the controller in realizing this function is described. This function realizes that no matter when the electric hoist starts up or down, the controller will monitor the braking signal of the hoist motor to ensure the normal braking operation of the hoist motor and the safe operation of the hoist. Traditional relay control needs at least a timer and several relays to achieve; while the controller can be realized by using the timer module and several basic logic modules in its own program, which saves the cost and wiring space of components, and reduces the hidden trouble caused by instability of components, so its advantages are obvious. However. Optimized operation microcontroller can also have a variety of optimization functions in electric hoist control system.
While guaranteeing the normal operation of the gourd, the performance and life of the gourd can be greatly reduced by optimizing its functions. Taking the optimization function of “preventing direct quick start” as an example [2], this function mainly prevents operators from directly and frequently starting hoisting mechanism with fast gear when using electric hoist, thus causing impact on motors and gearboxes, greatly shortening the service life of motors and gearboxes; using the timing module of the controller, the hoist can be started.（ Fast or slow) is mandatory to maintain at a slow speed for a short period of time, thus achieving the operation of preventing direct quick start.
By skillfully utilizing the advantages of the controller itself, it not only achieves the effect, but also has a high performance-price ratio without adding components and wiring. Small, easy to use, easy to understand programming software. It can also monitor and read data online by programming software to improve maintenance efficiency.
Compared with independent switchgear, it has high flexibility and obvious price advantage. The abundant extension modules enhance its position in the automatic control function. For example, the AS-i function of its communication module can be used as the master/slave station in the complex system with fieldbus, which shows its advantage of function expansion. As China is gradually becoming a global manufacturing base for machinery and equipment, the domestic crane industry is also developing rapidly. In the fiercely competitive market, in order to pursue higher profits and market share, micro-controller replaces traditional relays or single-chip microcontroller as a control solution, which will be a choice for profit and technological change. In order to improve production efficiency and management, information technology of factories, networking of production equipment and centralized monitoring and management will become a trend. The powerful function expansion of microcontrollers is no less than that of PLC. While guaranteeing functions, the huge price advantage will be a bright spot. This paper briefly introduces the application of microcontroller in electric control of electric hoist. Compared with traditional relay control, microcontroller is flexible, powerful and cost-effective. With the development of electric hoist in China and the improvement of control technology, its application is bound to have a broader development prospect.