JPH11197550A - Output controller of induction motor for driving centrifuge - Google Patents

Abstract

PROBLEM TO BE SOLVED: To protect a converter device while limiting the outputs of induction motors by automatically decreasing the acceleration and deceleration rates of all inverters when the total sum of the respective induction motor outputs exceed the rated power of one unit of the converter device. SOLUTION: The values detected by speed detectors 1a to 1c and torque detectors 2a to 2c are multiplied by a multiplier 8 and output conversion constant setters 4a to 4c are subjected to division by a divider 9, by which the present values of the respective induction motor outputs are computed and, thereafter, the sum of all the induction motor outputs is obtd. by an adder 10. When this total sum exceeds the rated power of the converter device set in a dead zone constant setter 5, the acceleration and deceleration rates are automatically decreased by regulating the acceleration and deceleration time by the acceleration and deceleration time computing circuits 7a to 7c of all the inverters. As a result, the converter device may be protected while the outputs of the induction motors are limited.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a system in which an induction motor is driven by an inverter device, and a plurality of devices are connected to each other by a single converter. And an output control device for an induction motor.

[0002]

2. Description of the Related Art In general, there are cases where an induction motor is driven by a plurality of inverter devices and controlled by a single converter.

[0003]

However, in a control device that performs control in such a manner, when the converter device is selected to be equal to or more than the total output of the induction motor, the operation rate of each induction motor is taken into consideration. Therefore, in a normal use, resources and an installation place are wasted by extra installation of devices. Also, if it is necessary to simultaneously accelerate and decelerate each motor simply by considering the operation rate of the induction motor, the total output of the induction motors will exceed the rated output of the converter, especially when all induction motors are simultaneously decelerated in an emergency. Therefore, the converter device performs an overload protection operation, and all the induction motors become uncontrollable. Conventionally, there is no device for controlling the output of the induction motor, and a uneconomical converter device having a rated output equal to or greater than the sum of the outputs of the induction motors is required. The present invention has been made in view of the above points, and an object of the present invention is to provide an output control device of an induction motor for driving a centrifuge that solves these drawbacks.

[0004]

In other words, the means for achieving the object is to realize a highly safe induction motor control while effectively using resources. Using a programmable controller, the output of each induction motor is multiplied by a speed (rpm) and a torque (%), and the result is divided by a constant for converting the output into an output. When the rated output of one of the converter devices is exceeded, the acceleration / deceleration rates of all the inverters are automatically reduced, thereby limiting the output of the induction motor and protecting the converter device. Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.

[0005]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a main part configuration diagram showing an embodiment using an output control device of an induction motor for driving a centrifuge according to the present invention. In FIG. 1, 1a-
1c is an inverter, 2a-2c are speed detectors, 3a-3
c is a torque detector, 4a to 4c are output conversion constant setting devices,
5 is a dead band constant setting device, 6 is an acceleration / deceleration time conversion constant setting device, 7a to 7c are acceleration / deceleration time calculation circuits provided in each inverter, 71 is a set speed, 72 is a set time, 8
Is a multiplier, 9 is a divider, and 10 is an adder.

According to the present invention, a plurality of induction motors for driving a centrifugal separator are controlled by an inverter using a single converter, and the output of each induction motor is controlled by a programmable controller using a speed controller. rpm) and torque (%) are divided by a constant for converting to output, and the calculation is performed. When the total output of all induction motors exceeds the rated output of one converter device, all inverters are output. The output of the induction motor is limited by automatically reducing the acceleration / deceleration rate.

That is, the values detected by the speed detectors 1a to 1c and the torque detectors 2a to 2c are multiplied by a multiplier 8,
The output conversion constant setting devices 4a to 4c are divided by a divider 9 to calculate the current value of each induction motor output,
Thereafter, all the outputs of the induction motor are added to the adder 10.
And sum them up. When the rated output value of the converter device is set in the dead zone constant setting device 5 and the sum of the output of the induction motor from the adder 10 exceeds the dead zone region and starts to gradually output a numerical value, the acceleration / deceleration time conversion constant setting device 6 The division is performed by the divider 9 according to the output signal. Thereafter, this output signal is added to the add / subtract time calculation circuits 7a to 7 in each inverter.
c (acceleration / deceleration rate operation circuit) is added to the value of the set time 72, and the value of the set speed 71 is divided by the divider 9 to adjust the acceleration / deceleration time. As a result, all the induction motors are automatically controlled.

[0008]

As described above, according to the present invention, when the converter device is selected to have a higher output than the total output of the induction motor, the operation rate of each induction motor is not taken into account. If the installation and the place where the resources and the installation place were wasted are eliminated, and it was necessary to accelerate and decelerate each at the same time simply by considering the operation rate of the induction motor,
Especially when all induction motors are decelerated at the same time in an emergency, the sum of the output of the induction motors may exceed the rated output of the converter, the converter device operates overload protection, and all the induction motors become uncontrollable. The lack has been eliminated and the safety can be ensured, and it is extremely useful in practical use.

[Brief description of the drawings]

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

[Explanation of symbols]

 1a-1c Inverter 2a-2c Speed detector 3a-3c Torque detector 4a-4c Output conversion constant setting unit 5 Dead zone constant setting unit 6 Acceleration / deceleration time conversion constant setting unit 7a-7c Acceleration / deceleration time calculation circuit 71 Setting speed 72 setting Time 8 Multiplier 9 Divider 10 Adder

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code FI H02P 7/63 302 H02P 7/63 302M 7/74 7/74 G

Claims (1)

[Claims] An apparatus for controlling a plurality of induction motors for driving a centrifugal separator by using a single converter device, wherein the output of each induction motor is detected by a speed detector and a torque detector by using a programmable controller. , The speed (rpm) and torque (%) are detected, and the detected value is multiplied by a divider, divided by a constant for converting the output to an output, and all the induction motor outputs of the divided value are added to the adder. If the total sum exceeds the rated output of one converter set in the dead band constant setting unit, the acceleration / deceleration rate of all inverters is automatically reduced by the acceleration / deceleration time calculation circuit. The output of the induction motor for driving the centrifuge, characterized in that the output of the induction motor is limited by Control device.