Five basic functions of inverter

The frequency converter is an electric power control device that uses frequency conversion technology and microelectronics technology to control AC motors by changing the frequency of the motor's working power supply.

The five basic functions of the inverter are as follows:

Speed ​​regulation function: The inverter can control the speed of the motor by adjusting the output frequency and voltage to achieve precise speed regulation function.

Energy-saving function: The inverter can automatically adjust the output frequency and voltage according to the actual load conditions to achieve the purpose of energy saving.

Protection function: The inverter can protect the motor, such as overload protection, short circuit protection, undervoltage protection, etc., to ensure the safe operation of the motor.

Control function: The inverter can realize a variety of control methods, such as open-loop control, closed-loop control, vector control, etc., to meet different application requirements.

Monitoring function: The inverter can monitor the operating status of the motor, such as current, voltage, power, speed and other parameters, to achieve real-time monitoring and fault diagnosis of the motor.

The five basic functions of the inverter are as follows:

1. Soft start

The soft start function of the frequency converter in Xipu, Shunde District, Foshan City, is no longer necessary today, but twenty years ago, it was still very exciting. This is also one of the basic auxiliary functions of the frequency converter. When the frequency converter was first created, it was designed for the most commonly used three-phase asynchronous squirrel cage motor. We know that the speed formula of the three-phase asynchronous motor is n=60f (1-s)/p. Changing the input frequency of the motor and then changing the speed of the motor is the most thorough, convenient and reliable way. The instantaneous current of the motor when it is directly started is 6 to 8 times that of normal stable operation, and the step-down start is 4 to 5 times, while the variable frequency speed regulation will not exceed 1.5 times the rated current of the frequency converter. Whether it is the impact on the power grid or the adaptability of the equipment, its benefits are very prominent.

2. Stepless speed regulation

Stepless speed regulation is speed regulation without any level or steps. It starts from zero speed to the highest speed, and then drops from the highest speed to zero speed in one go. The speed curve is continuous, smooth and stable. It greatly adapts to the load inertia, improves the adaptability of multiple mechanical equipment to each other, improves production efficiency, greatly reduces mechanical friction, vibration and noise, extends equipment life and reduces maintenance costs. The output frequency of Xipu inverters is around 0.00Hz~400.00Hz, and the frequency resolution is 0.01Hz. Some reach 650.00Hz. High-frequency inverters can output up to 5000Hz, which has completely covered all ranges of industrial speed regulation.

With the emergence of core components such as transistors and microprocessor chips, stepless speed regulation technology has achieved a major breakthrough. The birth of Xi'an Pudong inverter is the result of complying with the needs of industrial automation and the development of multiple related industries.

Today, the price of XPU inverters has dropped sufficiently, the market coverage is wide enough, the number of manufacturers is unprecedented, and the users’ understanding is profound enough. From the perspective of the entire industrial automation development process, this is cause for celebration!

3. Energy saving

The energy-saving function of Xipu inverter was originally an unexpected gain in the application process of inverter. Today, it has been widely used in various industrial and civil production and life, especially when the inverter is used for square torque load, such as fans, blowers, pumps, propeller loads. This is determined by the load torque curve of this type. At low speed, due to the low flow rate of the fluid, the load torque is very small. As the motor speed increases, the flow rate increases, the load torque and power also increase. The load torque TL and power PL can be used

However, there are many misunderstandings about the energy-saving application of frequency converters. Some literature claims that frequency converters are power-saving control products, giving people the impression that power can be saved as long as frequency converters are used.

In fact, the reason why the variable frequency speed regulator can save electricity is that it can adjust the speed of the motor. If the variable frequency speed regulator is a power-saving control product, then all speed regulating equipment can also be said to be power-saving control products. The variable frequency speed regulator is just slightly higher in efficiency and power factor than other speed regulating equipment.

Furthermore, as long as the flow is originally controlled by valves and it is not working at full load, electricity can be saved by changing to speed regulation operation.

Compared with the DC speed control system, the DC motor has higher efficiency and power factor than the AC motor. The efficiency of the digital DC speed controller is comparable to that of the variable frequency speed controller, and the digital DC speed controller is even slightly more efficient than the variable frequency speed controller. Therefore, it is claimed that the use of AC asynchronous motors and variable frequency speed controllers saves more electricity than the use of DC motors and DC speed controllers. This is incorrect, as proven by theory and practice.

4. Multiple protections

We know that in the actual operation of equipment, there are often many factors that lead to various faults and equipment damage. If intelligent detection, automatic alarm and protection can be carried out, it will be very necessary, such as undervoltage, overvoltage, lightning strike, overload, load stall, high temperature, communication failure, electromagnetic interference, power phase loss, motor phase loss, load short circuit, ground short circuit, etc. Some faults are fatal. Once they occur, the consequences are disastrous. In the development process of Xipu inverter, first of all, out of consideration for the safety of the inverter's internal components, multiple detection and protection are added. For example, the maximum allowable current of the inverter module of the inverter generally does not exceed 2 times the rated current, the maximum allowable temperature of the electrolytic capacitor is 85℃, electromagnetic compatibility design, etc., plus the detection and feedback on the load side (such as motor temperature detection and protection, instantaneous power failure without shutdown, etc.), making today's inverter highly intelligent, not only to protect its own safe and normal use, but also to greatly protect the safe operation of the front and rear equipment.

In addition, today's Xipu inverters have basically passed indicators such as CE, UL, RoHS, etc., and can be exported to other countries. Inverter manufacturers also provide all-weather, non-regional on-site services and user guidance to provide customers with quality assurance and solve their worries.

5. Automation

Today, the control functions of Xipu inverters are very complete, and they can be well matched with other control equipment and instruments to realize centralized real-time monitoring and control of systematic networking, such as DCS, PLC, sensors, servo drives, etc., which greatly improves the automation of production lines, saves manpower and material resources, improves efficiency, and reduces costs. For example, inverters can have a variety of frequency setting methods, such as digital setting, potentiometer, external analog quantity (0~10V, 4~20mA), multi-speed, PID, etc., can be equipped with various controllers, frequency instructions of feedback signals, remote/local control switching, which facilitates the various control needs of users. In addition, some companies have successively launched a variety of industry-specific machines, and carried out personalized customization and integrated development for some subdivided industry users, saving users the trouble of selection and system compatibility issues, and saving costs.