There are many variable frequency drive types, and their classification methods are also diverse. They can be classified according to their uses, conversion methods, power supply properties, frequency conversion control, and other methods according to needs. Just learn more from this article.
Variable frequency drive types by usage
According Variable frequency drives’ usage, it can be divided into two different types of vfd: general Variable frequency drive s and special Variable frequency drives according to their uses.
General-purpose inverter: General-purpose inverter refers to an inverter with strong versatility in many aspects. This type of inverter simplifies some system functions and is mainly for energy saving. It is mostly a small and medium-capacity inverter and is generally used in water pumps., fans, blowers and other occasions that do not require high system speed regulation performance.
Special Variable frequency drive: Special Variable frequency drive refers to a Variable frequency drive designed and developed specifically for a certain aspect or field. This type of Variable frequency drive is highly targeted and has unique functions and advantages suitable for the field it targets, so that it can Better play the role of frequency conversion speed regulation.
2. variable frequency drive types by transformation methods
There are two different types of vfd drives according to the frequency conversion method when they work: AC-DC-AC Variable frequency drives and AC-AC Variable frequency drive.
(1) AC-DC-AC Variable frequency drive: AC-DC-AC Variable frequency drive is also called indirect Variable frequency drive. It means that when the Variable frequency drive is working, it first converts the power frequency AC power into pulsating DC power through the rectifier unit, and then passes through the intermediate circuit. The capacitor smoothing filter in the inverter circuit supplies power to the inverter circuit; under the control of the control system, the inverter circuit converts the DC power into AC power with adjustable frequency and voltage, and then provides it to the load (motor) for variable speed control.
(2) AC-AC Variable frequency drive: AC-AC Variable frequency drive, also known as direct Variable frequency drive, means that when the Variable frequency drive is working, it directly converts power frequency AC power into AC power with adjustable frequency and voltage, and provides it to the load (motor) for operation. Variable speed control.
3. variable frequency drive types by power supply.
According to power supply, it can be divided into 2 different types of variable frequency drive: voltage-type Variable frequency drive s and current-type Variable frequency drives.
Voltage-type inverter: The characteristic of voltage-type inverter is that the intermediate circuit uses capacitors as DC energy storage components to buffer the reactive power of the load. The DC voltage is relatively stable, and the internal resistance of the DC power supply is small, which is equivalent to a voltage source. Therefore, voltage-type inverters are often used in situations where the load voltage changes greatly.
Current-type inverter: The characteristic of current-type inverter is that the intermediate circuit uses an inductor as a DC energy storage element to buffer the reactive power of the load, that is, to suppress the change of current and make the voltage close to a sine wave. Since the DC internal resistance is relatively small, Large, it can control frequent and sharp changes in load current, so current-type inverters are often used in situations where load current changes greatly, and are suitable for production machinery that requires feedback braking and frequent forward and reverse rotation.
Voltage-type inverters and current-type inverters not only differ in circuit structure, but also in performance and application range.
In addition, commonly used Variable frequency drives can also be divided into three-in and three-out Variable frequency drives and single-in and three-out Variable frequency drives according to the number of input current phases. Among them, three-in and three-out means that the input side and output side of the Variable frequency drive are both three-phase alternating current, and most Variable frequency drives belong to this category. Single input and three output means that the input side of the Variable frequency drive is single-phase alternating current and the output side is three-phase alternating current. Generally, Variable frequency drives in household electrical equipment use this method.
