VEICHI inverter-one master, multiple slaves，perfectly drives high-power loads

프로젝트 개요

With the continuous progress and development of the manufacturing industry, to improve production efficiency, the power level of production machinery and equipment is gradually increasing, which requires multiple motors of the same specification to synchronously drive high-power machinery and equipment. When one inverter drives multiple motors in parallel, it will be found that even if the maximum power inverter is used, the demand cannot be met, so it is necessary to adopt a one-master and multiple-slave approach. That is, each inverter drives one motor, and each motor is synchronized through one master and multiple slaves.

The following is the application of an on-site mixer. Our inverter adopts a master and three slave mode to control the synchronous operation of 4 motors to realize the mixing function. The power part of the mixer consists of 4 motors, and its structure is shown in the figure: motors M1 and M2 are coaxial rigid, M3, M4 are coaxial rigid connections, M1 and M3, M2 and M4 are rigidly connected with synchronous gears (That is to say, the 4 motors are rigidly connected in pairs, driving one motor and the other 3 motors can all be linked).

Because the four motors are rigidly connected in pairs, the inverter control synchronization requirements are extremely high. If one of the motors is not synchronized, it will cause damage to the mechanical bearing structure and abnormal noise. To achieve high-precision synchronous control, combined with customer needs, our company has made a "power balance" drive scheme to make the drive effect perfect.

The power balance scheme has extremely high requirements on the control performance of the inverter, and the following points should be noted:

1. "Power balance", as the name implies, is to ensure that the output power of each inverter drive motor is equal at all times, to eliminate the torque between the motors, no abnormal noise, and achieve perfect control. This process requires the inverter to respond quickly, accurately and accurately.
2. To achieve rapid information exchange between the four inverters, our company uses CAN card for communication. Combining the advantages of CAN bus communication speed, stable performance, and strong anti-interference ability, it is perfectly used in the power balance scheme, thus ensuring the reliability of the scheme.
3. The specific way to realize this kind of scheme is: define one of them as the master, and the remaining three as slaves. The master and slaves are connected through CAN card communication. The running frequency of the slaves is equal to the master plus PID adjustment (f slave =f main+PID).
4. PID adjustment detects the difference between the active current of the master and the active current of the slave through CAN communication, and realizes the automatic adjustment of the output frequency of each slave, to realize the same output power of 4 motors at all times and ensure the driving performance reliability.
5. At present, this kind of power balance-one-master-multi-slave mode adopts the master and slave running speed mode. In the future, if there is a need for a higher response, you can use the master running speed mode and the slave running torque mode.

The power balance realizes the high-precision synchronous drive of multiple motors, and it is also necessary to implement a strict protection scheme for the inverter and machinery, such as the following scheme:

1. When the host fails, the host will send a free stop command to each slave.
2. When one of the slaves fails, the failed slave sends a free stop command to the master, and the master sends a free stop signal to the other slaves.
3. To avoid the damage to the mixing arm caused by the free stop, the deceleration stop mode is adopted, so that each inverter can stop working at the same time, thus ensuring the integrity of the machine.
4. It is this strict protection mechanism that not only guarantees the highly reliable operation of the inverter but also minimizes the mechanical loss when the inverter fails. So that every customer can get a high degree of recognition for VEICHI products and solutions!

At present, the "one master, multiple slaves" program of our frequency converter is very mature and has been used on many occasions, such as coal mine belt conveyor, food belt conveyor, sand, and gravel belt conveyor, mixer, crusher, etc. With the continuous development and progress of the industry, "one master, multiple slaves" will become a trend in the future, and VEICHI will be ahead of the trend and provide better technical solutions for the industrial control industry. At present, our solution is mature and perfect, and it will be even more perfect in the future because we are constantly making breakthroughs and progress!