【Daily Question 20090304】Can phase control be used with inverters?
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【Daily Question 20090304】During the commissioning of an inverter, it was found that the motor was rotating in the wrong direction; someone adjusted the phase on the power supply side of the inverter. Is this acceptable? Why?
No need to adjust the phase, right? The inverter itself has a function to set forward and reverse rotation; if the motor is rotating in the reverse direction, its parameters can be adjusted, and after power is restored, it will rotate in the forward direction.
The wire-tuning method can be used, but it’s rather cumbersome. Since the inverter already has forward and reverse operation functions, it can be done by modifying the parameters. Therefore, it’s fine to phase-shift or not to phase-shift.
Of course, you can do as the original poster did. However, since the inverter has a built-in function for reversing rotation direction, the parameters can be adjusted to be the opposite of the original settings. This is simpler.
The wire-tuning method can be used, but it’s rather cumbersome. Since the inverter already has forward and reverse operation functions, it can be done by modifying the parameters. Therefore, it’s fine to phase-shift or not to phase-shift.
The input cable generally doesn’t need to be adjusted; it’s sufficient to adjust the cables connected to the motor at the output side. The input cable is often restricted by length or space, making it difficult to manipulate. Changing the parameters to alter the rotation direction is also an option.
No need. Some keyboards have dedicated buttons for forward/reverse (FWD/RUN); pressing either button will result in the corresponding direction of rotation. It is also possible to set this via function codes. Another method involves terminal control: connecting the common terminal to the forward terminal (FWD) enables forward rotation, while disconnecting it from the reverse terminal (RUN) enables reverse rotation. When switching between forward and reverse rotation, it is important to ensure that the acceleration and deceleration times (which can be set via function codes) are appropriate
No need. The inverter has a reverse function; just adjust the parameters
No need; it can be set on the inverter itself.
Just adjust the parameters; it’s not necessary. The frequency converter has a reverse function.
The inverter itself has a function for setting forward and reverse rotation, which can be achieved by adjusting the wires; however, this method is somewhat…***
No need; just adjust the parameters. The inverter has a reverse function.!
No, adjusting the power phase sequence on the power supply side of the inverter does not mean that the power phase sequence on the output side of the inverter will change; therefore, the rotation direction of the motor does not necessarily change. The reason is that the frequency converters we use today primarily operate on the AC-DC-AC principle (VVVF frequency conversion or vector control frequency conversion): the mains AC power is first converted into DC power using a rectifier, and then that DC power is transformed into AC power whose frequency and voltage can be controlled, in order to supply the motor. The circuit of an inverter generally consists of four parts: rectification, intermediate DC link, inversion, and control. The rectification section is a three-phase bridge-type uncontrolled rectifier, the inversion section is an IGBT three-phase bridge-type inverter, and the output is in PWM waveform form; the intermediate DC link serves for filtering, storing DC energy, and buffering reactive power. Adjusting the phase sequence on the power supply side has no effect on the DC link, and thus it also has no impact on the DC inverter; therefore, the power supply phase sequence needs to be adjusted from the output side.
The question posed by the original poster is whether phase modulation at the power input side of the inverter can change the direction of rotation of the motor Phasing adjustment on the power inlet side of the inverter cannot change the motor’s direction of rotation.
Phasing adjustment on the power input side of the inverter should not be able to change the direction of rotation of the motor!
Of course, it’s possible – the frequency converter indeed has this function. However, it is recommended to adjust the wiring once, as many things need to be changed; for example, the 4-40MA parameter used for feeding feedback signals to the DCS will become negative.
I think it’s sufficient to adjust the wires connecting the motor to the output; the incoming wires are often restricted by length or space, making them difficult to handle. Changing the parameters to alter the direction of rotation is also an option. This might be the simplest!
Inverters can adjust the phase sequence; in practical use, it has been found that if the motor rotates in the reverse direction, the phase sequence can be adjusted via the control panel to make the motor rotate in the correct direction.