How to choose the inverter

First look at the rated power and rated current of the motor, then see if it is constant torque or variable torque load, and how much volts you use to input the inverter. Others look at communication or whether you want four or four quadrants. If the brand is made in China, the inverter technology is very mature now. There is no need to buy something as expensive as foreign countries.

In order to achieve constant torque regulation of large speed ratio, it is often used to increase the capacity of general-purpose inverters. For production machinery (such as papermaking machinery, injection molding machines, rolling mills, etc.) that require high precision, good dynamic performance and fast speed response, general-purpose inverters with vector control or direct torque control should be used.

1. Specifications and parameters of the motor

The inverter drives the motor during use. Therefore, the selection of the inverter can select the model and specification from the perspective of the motor.

Each motor has its own nameplate, and from the nameplate, we can easily find the parameters of the motor. Among these parameters, the main parameters we need to understand are: rated voltage, rated current, rated frequency, rated speed, etc. of the motor.

2, the rated voltage of the motor: the rated voltage of the motor is generally 110V, 220V, 380V, 690V, 1140V, 6kV and so on.

3. Rated current of the motor: The rated current of the motor varies according to the power of the motor. When selecting the inverter, the rated current of the inverter should be greater than or equal to the rated current of the motor. In special cases, the inverter power level should be amplified by one gear.

4, the rated frequency of the motor: the rated frequency of ordinary motors is generally 50 ~ 60Hz, high-speed motors have 1000 ~ 3000Hz. CH_100 series can meet the needs of 0~600Hz motor. For higher frequency, please use CH_150 series inverter. Rated speed of the motor: The motor is divided into 2 poles, 4 poles, 6 poles, 8 poles, etc. The higher the pole number, the lower the speed and the greater the same power current. The motor we use is rated at 1500 rpm for a 4-pole motor. The frequency converter is also designed according to the 4-pole motor. The 2 pole corresponds to 3000 rpm, the 6 pole corresponds to 960 rpm, and the 8 pole corresponds to 720 rpm.

5, temperature and humidity

The effect of temperature on the inverter: The ambient temperature of the inverter is generally applicable to -10 ° C ~ +40 ° C, humidity in the environment below 90%. If the ambient temperature is higher than 40 °C, the inverter should be derated by 5% for every 1 °C increase. When the ambient temperature is 10 °C per liter, the life of the inverter is halved, so the problem of ambient temperature and heat dissipation of the inverter must be solved.

Pay attention to the following issues when selecting a frequency converter:

1. The inverter power is selected according to the load power. How much power the inverter chooses. Freshman specifications are also available.

2. Different inverters are used for different types of inverters. For example, there are general-purpose inverters, inverters for fan and water pumps, and inverters for machine spindles. and many more.

3. When the load inertia is large, the brake unit and the braking resistor should be selected at the same time.

4. Check the rated current of the nameplate of the motor. (The rated current is measured when there is no nameplate.) The rated current of the inverter is larger than the maximum operating current of the motor.

It is very important to purchase the inverter correctly, because the inverter can not be used normally under any circumstances, so it is necessary for the user to know more about the load, environmental requirements and the inverter. The following are different ways to select the inverter for different industry load conditions:

1. Fans and pumps are the most common loads: the requirements for inverters are the simplest, as long as the capacity of the inverter is equal to the capacity of the motor (air compressors, deep pumps, sediment pumps, fast changing musical fountains need to increase capacity) .

2, crane load: This type of load is characterized by a large impact at startup, so the inverter is required to have a certain margin. At the same time, if the elbow is placed under the weight, there will be energy feedback, so use the brake unit or use the common bus method.

3. Uneven load: Some loads are sometimes light and sometimes heavy. At this time, the inverter capacity should be selected according to the heavy load, such as rolling mill machinery, crushing machinery, mixer, etc.

4, large inertia load: such as centrifuge, punch, cement plant rotary kiln, such load inertia is very large, so it may oscillate when starting, there is energy feedback when the motor decelerates. A slightly larger frequency converter should be used to speed up the start-up and avoid oscillation. The brake unit is used to eliminate the feedback energy.