Frequency inverter

A frequency inverter is an electronic device that controls the speed and power of an electric motor. It is used to change the frequency of the alternating current that drives the motor in order to achieve the desired speed and power.

The frequency inverter converts the input alternating current into direct current and then generates a new alternating current with an adjustable frequency and voltage. The frequency inverter can vary the speed of the motor by changing the frequency and voltage.

Frequency inverters are used in various areas, such as industry, elevators, air conditioning technology, conveyor technology and automation technology. They enable precise control of the motor speed, which can lead to energy savings, better regulation and a longer motor service life.

A frequency inverter is an electronic device that changes the frequency and voltage of an alternating electric current to control the speed of an electric motor. It is often used in industrial applications to control the speed of machines, pumps, fans and other drive devices.

The main components of a frequency inverter are

1. Rectifier: The rectifier converts the alternating current into direct current by removing the negative half-waves of the alternating current. This direct current is then used to feed the intermediate circuit.

2. DC link: The intermediate circuit consists of capacitors that store and smooth the direct current. This stored energy is then used to generate the voltage and frequency required for the motor.

3. Inverter: The inverter converts the direct current from the intermediate circuit back into a modulated alternating current. The frequency and voltage of the alternating current are changed according to the requirements of the motor. The inverter consists of transistors or thyristors that switch the direct current up and down to generate the desired output wave.

4. Control electronics: The control electronics control the frequency inverter and enable the speed of the motor to be adjusted. It contains microcontrollers, sensors and other electronic components that process the input signals and send the output signals to the inverter.

In addition to these main components, frequency inverters can also have additional protection and monitoring devices, such as overcurrent protection, overheating protection, short-circuit protection and a display to show operating parameters.

Overall, the frequency inverter enables precise control of the speed of electric motors, which leads to improved energy efficiency, a longer service life of the drive devices and better process control.

Frequency inverters offer various advantages in industrial applications:

1. Energy saving: Frequency inverters enable precise adjustment of the motor speed to the current demand, thereby reducing energy consumption. This is particularly advantageous in applications with a variable load profile, such as pumps or fans.

2. Improved process control: Thanks to the ability to precisely control the motor speed, frequency inverters can enable precise control of the process. This allows production speeds to be optimized, for example, or specific requirements such as certain pressure or flow rates to be achieved.

3. Reduced mechanical load: The gentle starting and stopping ramp of the motors with frequency inverters reduces the mechanical load on the drive components, such as gearboxes or clutches. This leads to a longer service life for these components and a lower failure rate.

4. Flexibility: Frequency inverters allow the motor speed to be adapted to different requirements without having to make mechanical changes to the drive unit. This means that machines can be used more flexibly and perform different tasks.

5. Better grid stability: By using frequency converters, peak current loads can be avoided, which leads to better stability of the power grid. This is particularly important in areas with limited network capacity or in networks with many machines and systems.

Overall, frequency inverters in industrial applications offer improved energy efficiency, process control and flexibility, resulting in cost savings, higher productivity and a longer service life for drive components.

Frequency inverters can control various types of motors, including

1. Asynchronous motors: These are the most commonly used motors and are used in many applications, including pumps, fans, compressors and conveyor belts.

2. Synchronous motors: These motors are often used in industrial applications where precise speed control is required, such as in printing machines or CNC machines.

3. Stepper motors: Stepper motors are often used in applications where precise positioning is required, such as in robots or CNC machines.

4. Direct current motors: DC motors can also be controlled with frequency inverters to enable precise speed control.

However, it is important to note that not all motors can be controlled with frequency inverters. Some motors, such as brushless DC motors, require special drives to control them.

A frequency inverter enables the speed and torque of an electric motor to be controlled. Various parameters can be set to influence the motor performance:

1. Frequency: The output frequency of the frequency inverter determines the speed of the motor. The speed can be adjusted accordingly by increasing or decreasing the frequency. A higher frequency leads to a higher speed and vice versa.

2. Voltage: The frequency inverter can adapt the output voltage to the motor. A higher voltage leads to a higher power output and thus to a higher torque output from the motor.

3. Current limitation: The frequency inverter can set a maximum current value for the motor. This parameter limits the power consumption of the motor and protects it from overloading.

4. Acceleration and deceleration: The frequency inverter makes it possible to set the acceleration and deceleration times of the motor. This allows the speed change of the motor to be controlled and a smooth starting and braking phase to be achieved.

5. Control type: The frequency inverter can support various types of control, such as vector control or V/f control. These influence the accuracy and dynamics of the motor control.

6. Motor parameters: The frequency inverter can set various motor parameters, such as the number of poles, winding resistance or inductance. These parameters are important in order to achieve an optimum match between the frequency inverter and the motor and to maximize the performance of the motor.

By setting these parameters, the frequency inverter can influence the motor power and adapt it to the requirements of the application. Optimum adjustment enables efficient and precise engine control.

A frequency inverter can help to save energy by regulating the speed of electric motors.

By adjusting the speed to the actual demand, the energy consumption of the motor is reduced. If, for example, a motor only needs to be operated at 80% of the rated speed, the frequency inverter can reduce the speed accordingly and thus reduce energy consumption by up to 50%.

In addition, frequency inverters also enable motors to be started up and slowed down smoothly, which prevents energy losses due to high current peaks. This reduces wear on the electric drives and extends the service life of the motors.

Another advantage of frequency inverters is the possibility of energy recovery. When a motor is decelerated, the frequency inverter can feed the energy generated back into the power grid instead of losing it in the form of heat. This can further reduce energy consumption.

All in all, frequency inverters contribute to energy efficiency by optimally adapting motor operation to actual requirements, minimizing energy losses and recovering energy where necessary.

The following safety precautions should be observed when handling a frequency inverter:

1. Switch off the power: Before working on the frequency inverter, the power supply must be switched off to prevent electric shocks.

2. Grounding: The frequency inverter must be properly earthed to prevent electrical interference and to ensure protection against electric shock.

3. Protective clothing: It is recommended to wear protective clothing such as safety shoes, safety goggles and gloves to avoid injury.

4. Follow instructions: It is important to follow the manufacturer's instructions exactly. This includes the installation, operation and maintenance of the frequency inverter.

5. Competent persons: Handling a frequency inverter requires specialist knowledge. Only qualified persons should install, operate and maintain the frequency inverter.

6. Avoid overheating: The frequency inverter generates heat. It is important to ensure that it is sufficiently ventilated and does not overheat.

7. Fuse switch: A fuse switch should be installed near the frequency inverter so that the power can be switched off quickly in an emergency.

8. Maintenance: Regular maintenance should be carried out in accordance with the manufacturer's instructions to ensure safe and efficient use of the frequency inverter.

It is important to note that these are general safety instructions and further safety precautions may be required depending on the specific model of frequency inverter. Therefore, the manufacturer's specific instructions should always be followed.

There are several current trends and developments in frequency inverter technology:

1. Increased energy efficiency: Frequency inverters are constantly being improved in order to optimize energy consumption. By using highly efficient power semiconductors and improved circuit designs, modern frequency inverters can significantly reduce energy consumption.

2. Compact design: The size and weight of frequency inverters are being continuously reduced. This enables space-saving installation and facilitates integration into existing systems.

3. Digital networking: Frequency inverters can communicate with other components in a system via various digital interfaces, such as Ethernet or field buses. This enables comprehensive monitoring and control of the drives and allows integration into the Internet of Things (IoT).

4. Improved control technology: By using modern control algorithms, frequency inverters can enable more precise and faster control of the motor speed. This improves the performance and accuracy of drive systems.

5. Safety and reliability: Frequency inverters are continuously being developed to ensure the safety and reliability of drive systems. This includes the integration of protective functions against overload, short circuit and voltage fluctuations as well as the monitoring of operating parameters for early fault detection.

6. Extended functionality: Modern frequency inverters offer a wide range of additional functions, such as soft start, brake chopper, integrated brake resistors, positioning control and energy management. This allows them to be flexibly adapted to different applications.

7. Use of silicon carbide (SiC) and gallium nitride (GaN): These new materials enable higher switching frequencies and lower losses in power semiconductors. This means that frequency inverters can be made even more efficient and compact.

These trends and developments contribute to the fact that frequency inverters play an important role in modern drive technology and can be used for a wide range of applications.