JPH11334041A - Method for controlling pwm inverter for driving printer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce a loss in a high speed range where a printing machine sound is high without giving a discomfort to an operator by controlling the relationship between a carrier frequency of a PWM inverter for driving a motor and a frequency of an output to a specific value between speeds at the times of printing and cleaning rolls. SOLUTION: The PWM inverter for driving a motor 6 mechanically coupled to rolls of a printing machine 8 is controlled even at the time of cleaning rolls by bringing the rolls into contact with a cleaning implement and rotating the rolls at a low speed in addition to the time of printing. Here, the relationship between a carrier frequency Fch of the inverter and an output frequency (f) of the inverter is controlled between speeds at the times of printing and roll cleaning so that a product of the N-th power (N=0.8 to 2.2) of the carrier frequency Fch and the output frequency (f) becomes a predetermined value. That is, the motor 6 is controlled by a speed control vector control inverter to be controlled by a controller 9.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for controlling an inverter for driving a printing press.

[0002]

2. Description of the Related Art FIG. 3 is a block diagram showing an example of a voltage type vector control inverter for driving a conventional sheet-fed rotary printing press. In FIG. 3, 1 is a power supply, 2 is a rectifier for converting AC to DC voltage, 3 is a filter capacitor, 4 is an inverter for converting DC voltage to AC voltage, 5 is a current detector for detecting AC output current, 6 is an induction motor, 7 is a pulse encoder for detecting the number of rotations of the motor, 8 is a load printing machine, and 91 is a control unit for driving the inverter 4. Reference numeral 11 denotes a speed setting device for setting a printing speed, 12 denotes a slow-moving operation signal for performing low-speed operation such as roll cleaning, and 13 denotes an operation signal for a printing area.

At the time of the slow operation, the output of the slow rotation speed setting device 23 is set by the slow operation signal 12 via the priority circuit 24, and the speed is set via the speed detector 25 to which the output signal of the pulse encoder 7 is input. The speed is controlled by a computing unit 26 and a speed computing unit 27, and the vector computing unit 28 that performs a torque computation by detecting the current and the motor rotation speed from the current detector 5 and the speed detector 25 using the output of the speed computing unit 27 as a torque command. ,
A PWM converter 29 for PWM-switching the self-extinguishing element in the inverter 4 at a constant carrier frequency to convert the output of the inverter 4 into a three-phase AC voltage, and the inverter 4 via a transistor driving circuit 30 To drive an induction motor (hereinafter referred to as a motor) 6.

During a printing operation, a speed setting signal is given from a speed setting device 11 via a contact 21, a ramp circuit 22 for increasing / decreasing a rising gradient of a motor rotation speed in a predetermined time, and a priority circuit 24 in response to an operation signal 13. The motor 6 is operated at a predetermined printing speed. During slow-running operation, it is an area where the operator touches the machine such as roll cleaning, so from the viewpoint of safety, overshoot is small, and high-precision speed control characteristics with little fluctuation in motor speed are required. Requires stable speed control characteristics that do not affect printing characteristics. Therefore, generally, vector control of a constant carrier frequency having a high frequency is used.

[0005]

During the washing operation, the operator checks and cleans the machine, so that a high number of carriers without PWM electromagnetic noise from the motor is required. However, since the printing machine is used in a bad environment with a lot of paper dust, the cubicle containing the inverter needs to be tightly sealed so that the paper dust does not enter.
Inverters housed in cubicles are also required to have low loss. Therefore, increasing the carrier frequency of the PWM increases the loss in the cubicle, which is a problem in cooling. SUMMARY OF THE INVENTION The present invention has been made in view of the above points, and aims to solve these drawbacks without giving a worker an uncomfortable feeling due to the motor electromagnetic noise, and at a high speed of the printing machine noise. It is an object of the present invention to provide an inverter device which can reduce the loss in the region and can easily cool the cubicle.

[0006]

Means for achieving the object is to provide a PWM inverter device for driving an electric motor mechanically coupled to a printing press roll, and to perform cleaning on the roll in addition to printing. When the roll is rotated by rotating the roll at a low speed by contacting the tool, the PWM inverter device controls the PWM inverter device to drive the motor. The relationship between the carrier frequency Fch of the PWM inverter device and the output frequency f of the PWM inverter device is expressed by the Nth power of the carrier frequency Fch (N =
0.8 to 2.2) and the output frequency f are controlled so as to have a constant value. Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.

[0007]

FIG. 1 is a block diagram showing one embodiment of the present invention, FIG. 2 is an explanatory diagram showing one embodiment of a carrier frequency of an inverter of the present invention, and FIG. 4 is a diagram showing load characteristics of a rotary printing press. In the explanatory diagram showing one embodiment, the same parts as those in FIG. 3 are represented by the same symbols, and the description thereof will be omitted. In FIG. 1, a PWM inverter device for driving a motor 6 mechanically connected to a printing press roll is provided. In addition to printing, a cleaning tool is brought into contact with the roll and the roll is rotated at a low speed to perform roll cleaning. In the PWM inverter for a printing press drive motor for controlling the PWM inverter and driving the motor 6 also when performing, the carrier frequency F of the PWM inverter between the speed at the time of printing and the speed at the time of roll washing is set.
ch and the output frequency f of the PWM inverter device
This is a method of controlling so that the product of the Nth power of the carrier frequency Fch (N = 0.8 to 2.2) and the output frequency f becomes a constant value.

That is, the motor 6 for driving the printing press is controlled by a speed control vector control inverter controlled by the controller 9. In FIG. 4, the horizontal axis represents the machine rotation speed N and the vertical axis represents the load torque T. As shown in FIG. 4, in the rotary printing press, the load torque is small in the low speed region, and the square of the machine speed increases as the speed increases. Requires a high load torque proportional to. In FIG. 1, reference numeral 31 denotes a PWM carrier frequency setting unit which is connected to a PWM converter 29 and changes the carrier frequency of the inverter by the setting unit 31. By inputting the output signal of the speed detector 25, the output signal of the PWM carrier frequency setting unit 31 is changed to a PWM inverter such that the printing machine load characteristic as shown in FIG. Is set as a pattern according to the motor speed. In FIG. 2, the horizontal axis represents the motor rotation speed N, and the vertical axis represents the carrier frequency fch. The PWM carrier frequency fch of the inverter changes according to the characteristics shown in FIG. 2 according to the motor rotation speed, and the carrier frequency fch of the PWM is high at a slow speed, and becomes lower as the speed increases.

[0009]

As described above, according to the present invention, the PWM frequency of the inverter device is such that the motor is operated in a quiet state in a low speed region where the motor is slow and the mechanical sound is small as shown in FIG. Since the loss can be reduced in the high speed region where the printing machine noise is high without giving any discomfort due to the motor electromagnetic noise, an inverter device that can easily cool the cubicle can be obtained, which is extremely useful in practical use. In the present invention, an example in which speed control is performed using an encoder has been described. However, the present invention can also be applied to a speed sensorless inverter that performs speed control using a motor rotation speed calculated from detection signals such as motor current and voltage. Further, in the present invention, the motor speed is used as the motor speed signal of the carrier frequency setting unit 31, but it goes without saying that the speed setting signal of the speed controller may be used.

[Brief description of the drawings]

FIG. 1 is a block diagram showing one embodiment of the present invention.

FIG. 2 is an explanatory diagram showing one embodiment of a carrier frequency of the inverter of the present invention.

FIG. 3 is a block diagram showing an example of the related art.

FIG. 4 is an explanatory diagram showing an example of load characteristics of a rotary printing press.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Power supply 2 Rectifier 3 Filter capacitor 4 Inverter 5 Current detector 6 Induction motor 7 Pulse encoder 8 Printing machine 9 Speed controller 11 Speed setting device 12 Slow operation signal 13 Printing operation signal 21 Contact point 22 Inclination circuit 23 Slow speed Setting device 24 Priority circuit 25 Speed detector 26 Computing device 27 Speed controller 28 Vector controller 29 PWM converter 30 Transistor drive circuit 31 Carrier frequency setting device

Claims (1)

[Claims] The present invention further comprises a PWM inverter device for driving an electric motor mechanically coupled to a printing press roll. In addition to printing, when a cleaning tool is brought into contact with the roll and the roll is rotated at a low speed to perform roll cleaning. Also controls the PWM inverter to drive the motor,
In the WM inverter device, the relationship between the carrier frequency Fch of the PWM inverter device and the output frequency f of the PWM inverter device between the speed at the time of printing and the speed at the time of roll cleaning is expressed by the Nth power of the carrier frequency Fch (N = 0). .8
-2.2) and a control method of a PWM inverter for driving a printing press, wherein the product is controlled so that the product of the output frequency f and the output frequency f becomes a constant value.