JPH0467799A - Voltage control method of loom inverter - Google Patents

Abstract

PURPOSE:To contrive to shorten a starting time, etc., while preventing overexcitation in a loom inverter for keeping the ratio of frequency to voltage constant by giving a torque boost in an operating range from starting to rated speed and by returning the ratio of frequency to voltage to a constant value at the time of reaching the rated speed. CONSTITUTION:The frequency command (f) of a frequency controller 6 is take in CPU 11, which compares the frequency command (f) and rated speed and conducts a torque boost until the command (f) reaches the rated speed. Therefore, the torque boost is given from starting to the rated speed to make a voltage higher at the time of acceleration to generate a high torque and to shorten a starting time from starting to the rated speed. After the rated speed is reached, the torque boost is cut so that a normal F/V constant control is returned and overexcitation is prevented. Also, if the torque boost is given when deceleration begins by generation of a temporary overload because the torque boost is given during acceleration, it is possible to reduce the decrease and variation of speed due to overload.

Description

[Detailed description of the invention] A. Industrial application field The present invention relates to a voltage control method for an inverter for a loom.

B. Summary of the Invention The present invention provides a torque boost from startup to rated speed in a loom inverter that has an oven loop configuration and keeps the ratio of frequency and voltage constant, thereby shortening the startup time while preventing overexcitation. The aim is to

C1 Conventional technology FIG. 2 shows a block diagram of an inverter for a loom.

A controlled voltage is transferred from the DC output of the rectifier 1 to the inverter 2.
2. Obtain an AC output of frequency and use one or more synchronous motors.3.
~3o is driven. The control device limits the acceleration/deceleration of the speed command from the speed setting section 4 through the cushion section 5, and generates a frequency command f, which controls the maximum output frequency FMAX by the frequency control section 6, and a torque boost by adding a stop to this. A voltage control unit 7 that obtains a voltage command ■ that controls F T and RQ, a PWM calculation unit 9 that obtains a PWM waveform from these voltages, a frequency command, and the output of the carrier wave generator 8, and an inverse conversion unit 2 that operates according to the PWM waveform. It includes a gate drive section 10 that drives the main switch. In addition, the CPU II as the control center performs constant speed control and inching control based on the speed command N to the speed setting section 4, performs acceleration/deceleration switching control to the cushion section 5, and controls the maximum output frequency to the frequency control section 6. and performs torque boost control on the voltage control section 7.

Here, for starting, a torque boost is performed to give a large starting torque in order to prevent uneven weaving and the like. This torque boost increases the voltage at low frequencies to obtain the desired starting torque.

D9 Problems to be solved by the invention Conventional starting methods perform a torque boost, but this torque boost only compensates for the torque at the time of starting, and the starting time from starting to constant speed is long (there was a problem) .

Note that if the torque boost is applied all the time, the motor will become overexcited, so it is applied only at startup.

SUMMARY OF THE INVENTION An object of the present invention is to provide a voltage control method that reduces startup time while preventing overexcitation.

Means for Solving the E0 Problem In order to achieve the above object, the present invention provides an inverter for a loom that maintains a constant ratio of frequency and voltage by giving a torque boost in the operating range from startup to rated speed, The ratio of frequency and voltage is returned to a constant level when the speed is reached, and torque boost is also applied in the acceleration range to accelerate the rise from startup to rated speed, and overexcitation is prevented by turning off torque boost at rated speed. .

F. Embodiment FIG. 1 is a block diagram of essential parts showing an embodiment of the present invention. The difference between this figure and FIG. 2 is that the frequency command f of the frequency control unit 6 is taken into the CPU II, the CPU II compares the frequency command f with the rated speed, and performs torque boost until the command f reaches the rated speed. At the point.

Therefore, a torque boost is applied from the start to the rated speed, increasing the voltage during acceleration to generate high torque, and shortening the startup time from startup to the rated speed. After reaching the rated speed, the torque boost is turned off to return to normal F/V constant control and prevent overexcitation.

Furthermore, since a torque boost is applied in the acceleration range, if a torque boost is applied when deceleration begins due to a temporary overload during normal operation, it is possible to reduce speed drops and fluctuations due to overload. Furthermore, since acceleration, constant speed, and deceleration are repeated during inching operation, by applying a torque boost only during acceleration, it is possible to perform inching operation with rapid repetition.

In the embodiment, a configuration may be adopted in which the CPU II is commanded to turn on/off the torque boost from the outside, and the torque boost is applied only when necessary.

G1 Effects of the Invention As described above, according to the present invention, since torque boost is applied from startup to rated speed, it is possible to shorten the acceleration time in the acceleration range, that is, shorten the startup time, and furthermore, the torque boost is applied from startup to rated speed. In this case, overexcitation can be prevented by turning off the torque boost.

In addition, by providing a torque boost during inching operation or when an overload occurs, control with improved stability and controllability can be achieved.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of main parts showing one embodiment of the present invention, and FIG.
The figure is a block diagram of an inverter for a loom. 2... Inverse conversion section, 4... Speed setting section, 5... Cushion section, 6... Frequency control section, 7... Voltage control section, 9... PWM calculation section, 11... CPU 0 Figure 1 Tengwan Wa row - Ku'guchi, 7 diagram 6 ---Country and number system # part 7-'i&, Anti-Kaikai Misaki part 9-PWM*1 part 1-CPU

Claims (1)

[Claims] (1) A loom inverter that maintains a constant frequency and voltage ratio is characterized by providing a torque boost in the operating range from startup to rated speed, and returning the frequency to voltage ratio to a constant level when the rated speed is reached. A voltage control method for an inverter for a loom.