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Big round machine application


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1. The situation
Debugging machines and equipment: knitting circular machine
 V&T Inverter Model: V5−H−4T−5.5G/7.5L

2. The industry introduction
Knitting large circular machines are now widely used in the textile industry. In this industry of big circular machine, the market potential of frequency converter is still quite large.

3. The system program and system wiring
At present, Dayuan has a relatively mature control system, which is basically controlled by single-chip microcomputer or PLC+ human-machine interface. Its function requirements for the inverter are very simple, only the terminal control starts and stops, the analog given frequency or the multi-segment frequency is given.

In terms of control performance, the inverter is required to provide a large low-frequency torque, because the load is heavy when weaving, and the jog response is required to be rapid. Here, our inverter adopts the speed sensorless vector control mode to improve the motor's steady speed accuracy and low frequency torque output.

The large circular machine requires the motor to absolutely prohibit reverse rotation and rotation, otherwise the needle of the needle bed will be bent or even broken. For large circular machine systems with one-way bearings, this effect can be ignored. If the system is completely reversed depending on the motor control, then the DC braking function should be properly used.

In terms of speed control, the system is required to operate at least at three speeds. First, the jog operation, the frequency is about 5−6Hz; the second is the normal high-speed weaving operation, the highest frequency can reach 80Hz; the third is the low-speed collection operation, when the cloth is woven to a certain length, it needs to be slowly collected at a low speed of about 20Hz. cloth. For multi-speed control, there are basically two control schemes. One solution is to use the analog given frequency, whether it is jog or high speed and low speed operation, the analog signal and the running command are given by the control system; the other scheme is to use the multi-stage frequency given by the inverter, the control system The multi-segment frequency switching signal is given, and the jog is also provided by the inverter's own jog function. The set frequency at high-speed weaving is given by the analog quantity or the inverter open-loop frequency number.

Control terminal wiring method:

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4. The debugging steps
◆ According to the motor nameplate, set the motor parameters and perform the rotation self-learning of the parameters.
P0.03=4; P0.04=1; P0.06=1; P5.00=2; P0.08=5; P0.09=0.8; P0.11=65; P0.13=65, P0. 10=0.5; P3.03=0.2; Pd.09=50; Pd.14=0.1; PA.09=1; Pd.01=0.8; Pd.03=1; Pd.05=50; Pd.17= 10; Pd. 33 = 0.
P0.11 and P0.13 65Hz, the maximum frequency can be gradually increased to 80Hz after the large circular machine is worn for a period of time.

The settings of P3.03, Pd.09 and Pd.14 are to improve the dynamic performance of the start and stop of the round machine. The large circular machine requires fast response at start-up, low-frequency and large torque output, and smooth and soft when stopping, to protect the equipment needle bed. Therefore, the starting frequency is reduced to 0.2 Hz, the vector control pre-excitation time is reduced to 0.1 S, and the S-segment curve time is added to 0.5 to ensure the smoothness of the frequency adjustment at the start and stop time, and then the braking torque is reduced by 50%. After repeated experiments, the parameters of this group achieved good control performance.

The function codes Pd.01, Pd.03 and Pd.05 are used to improve the vibration problem of the large circular machine at high speed. The ASR switching frequency is increased and the speed loop proportional gain is reduced to reduce the torque of the inverter at high speed. Output, reducing motor jitter, thereby improving the violent vibration of the entire machine at high speeds.

Pd.33 is to reduce the output current during balanced power operation.

5. The solution to the problem of on-site debugging◆ Should the control mode be vector control 1 or vector control 2?
The large circular machine has half of the control performance requirements for the inverter. The vector control 1 should meet the requirements. The blue sea Huateng speed sensorless vector control inverter can better improve the low frequency and large torque output of the large circular machine. Stable speed performance, especially low frequency and large torque output characteristics, works well.

However, during the on-site debugging process, it was found that the rotation phenomenon can be eliminated or improved after the DC braking function is started in the vector control 2 mode. Therefore, the large circular machine for on-site debugging adopts the vector control 2 mode.
◆ The motor shaft has a slight rotation at the start and stop moment
For machines equipped with one-way bearings in the large circular machine system, the effect of this slight rotation can be completely ignored. However, some large circular machines do not prohibit reverse rotation on the machine. When it is completely controlled by the motor, this problem needs to be taken seriously. A slight reversal may damage the dial.

Here, it is necessary to set the DC braking parameter of the stop to ensure that the inertia on the motor shaft is completely stopped by DC braking during the stop, and also ensure that the angle of the motor shaft is consistent with the angle of the PWM wave when starting, and the starting is solved. The problem of instantaneous motor shaft rotation.

P3.05=2, P3.06=2, P3.07=120, P3.08=0.5, 120% inverter rated current during shutdown, DC braking at 0.5Hz, continuous braking time 2s.

After setting the DC braking function, the problem of the motor shaft rotation at the start and stop can be basically reduced to a minimum, and the final effect is better than the actual effect of other foreign brand inverters.

6. Summary
At present, V&T vector control type V5−H frequency converter is obviously more than enough in terms of functional performance on the large circular machine. The competitive price/performance advantage is obvious.

In addition, V&T can also help customers reduce costs through customization. For example, the big circular machine has a complete set of mature control systems. At present, the more advanced control systems basically use touch screen + PLC control. The cost of the PLC controller is relatively high. V&T Inverter can be combined with human-machine interface such as touch screen, and utilizes 485 communication control to develop a customized control system for the large circular machine industry, namely the human-machine interface + large-circle machine industry-specific inverter, thus completely eliminating the intermediate PLC link. , can greatly reduce the cost of the circular machine system.

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