Choosing the type of inverter, according to the type of production machinery, speed regulation range, static speed precision, starting torque requirements, decided to choose that control mode of the inverter is most appropriate.
The so-called suitable is both easy to use, but also economical, in order to meet the basic conditions and requirements of technology and production.
1. Motors and inverters that need to be controlled 1) The pole number of the motor. General motor pole number to not more than (extremely appropriate, otherwise the inverter capacity will be appropriately increased. 2) torque characteristics, critical torque, acceleration torque. In the case of the same motor power, compared to the high overload torque mode, the inverter specification can be reduced to select. 3) Electromagnetic compatibility. To reduce the main power interference, the reactor can be added to the intermediate circuit or inverter input circuit when used, or the front isolation transformer should be installed.
Generally, when the motor and inverter distance more than 50m, they should be strung into the reactor, filter or shielded protective cable in the middle of them.
2. Selection of inverter power The system efficiency is equal to the product of the efficiency of the inverter and the efficiency of the motor, and the efficiency of the system is higher only when both are working under high efficiency.
From the point of view of efficiency, in the selection of inverter power, we should pay attention to the following points: 1) The power value of the inverter is most suitable compared with the power value of the motor, so that the inverter operates under high efficiency value. 2) when the power rating of the inverter is not the same as the power rating of the motor, the power of the inverter should be as close as possible to the power of the motor, but should be slightly larger than the power of the motor. 3) When the motor is a frequent start, braking work or in heavy load start and more frequent operation, you can choose a large level of inverter, in order to use the inverter long-term, safe operation. 4) After testing, the actual power of the motor does have a surplus, you can consider the use of power less than the power of the motor inverter, but pay attention to whether the instantaneous peak current will cause overcurrent protection action.
5) when the inverter and motor power is not the same, it is necessary to adjust the setting of the energy-saving program accordingly, in order to achieve a high energy-saving effect.
3. Selection of box structure of frequency converter The box structure of the inverter should be compatible with the environmental conditions, that is, the temperature, humidity, dust, ph, corrosive gas and other factors must be taken into account. The following types of structures are common for users to choose from: 1) Open type IPOO type itself inorganic box, suitable for installation in the electronic control box or electrical indoor screen, disk, rack, especially in the centralized use of multiple inverters, the choice of this type is better, but the environmental conditions are higher; 2) closed IP20 type for general use, There can be a small amount of dust or a little temperature, humidity occasions; 3) sealed type IP45 type suitable for industrial site conditions of poor environment; 4) closed type IP65 type suitable for poor environmental conditions, water, dust and a certain corrosive gas occasions.