JPS63181698A - Load share control system for motors - Google Patents

Abstract

PURPOSE:To equally share loads between a DC motor and an induction motor by outputting the same torque as that shared by the DC motor from the induc tion motor by means of a load share controller. CONSTITUTION:A plurality of DC motors 2 driven by a thyristor Leonard unit 1 are directly shaft-coupled, and an induction motor 4 driven by an inverter 3 is shaft-coupled to the motor 2 to drive a load 6. A speed reference is applied by a speed setter 7, and a current reference to the unit 1 is output by a speed controller 8 which inputs a deviation from a speed detector 5 for detecting the rotating speed of a load shaft. A frequency reference is output from the output of the controller 8 and the rotating speed from a frequency reference calculator 9 to the inverter 3. A load share control system is composed of the controller 8 and the calculator 9.

Description

[Detailed description of the invention] [Purpose of the invention] (Industrial application field) The present invention relates to a load sharing control device for an electric motor.

(Conventional technology) Conventionally, in facilities where multiple DC motors are used for load sharing and variable operation using thyristor Leonard devices, due to the characteristics of DC motors, maintenance of brushes and commutators requires a lot of effort. It was.

In contrast, induction motors do not have the above-mentioned drawbacks of DC motors. In order to reduce maintenance in equipment that currently uses a DC motor and thyristor/Leonard device for load sharing operation, a load sharing control device is required if the DC motor and thyristor/Leonard device are to be replaced with an induction motor and inverter one after another. However, no suitable equipment has been reported.

(Problems to be Solved by the Invention) As described above, equipment that performs load sharing operation control using a DC motor and a thyristor Leonard device is subjected to constant voltage/frequency (V/F) control in accordance with a frequency standard. When replacing the inverter and induction type MOJ machine one by one, output the current reference to the DC motor and thyristor Leonard device, and output the frequency reference to the inverter and induction motor.
A load sharing control device that enables load sharing between an induction motor and a DC motor and variable speed operation is required.

An object of the present invention is to provide a load sharing control device for this electric motor.

[Structure of the invention]

(Means for solving the problem) A speed control circuit that outputs a current reference to a thyristor Leonard device based on the deviation between a reference value from a speed setting device and a speed feedback value from a speed detector that detects the speed of a load shaft; A load sharing control device consisting of a reference frequency calculation circuit that outputs the operating frequency reference to the inverter connected to the induction motor so that the induction motor outputs the same torque as the 1 to 1 torque borne by the DC motor ! l! A facility in which an IJ machine and a DC motor are mechanically directly connected is operated by sharing the load between each motor.

(Function) The deviation between the speed reference by the speed setter and the actual speed feedback signal is proportional-integral (PI) controlled by the speed control circuit.
A torque reference is generated. This torque reference is output to the thyristor Leonard device as a current reference since in a DC motor, torque is proportional to current. From this torque reference value and the actual speed feedback signal, as shown in FIG. 2, an output frequency reference is outputted to the inverter that drives the induction motor. The speed vs. torque curve of an induction motor is V
/F constant control is expressed by a straight line that moves parallel to the operating frequency, so the 1-lux speed curve is moved in parallel so that it passes through the intersection of the frequency conversion value of the actual speed feedback signal and the torque reference. Then, as shown in Figure 2, the output torque is -0.
The frequency that results in is the operating reference frequency for the inverter. The torque speed curve of an induction motor is (y y') = a (x-x') ... (1
) However, y is torque, a is a constant determined by the characteristics of IM, X is frequency, y' is reference torque, and X' is frequency -:3- Since it is expressed as the actual speed converted into a number, the reference frequency is
It is obtained by calculating the frequency X when y=Q.

(Example) FIG. 1 shows an example of the present invention. A plurality of DC motors 2 driven by a Cyrisk-Leonard device 1 are directly connected to the shaft, and an induction motor 4 driven by an inverter 3 is directly connected to the DC motor 2 to drive a load 6. A speed reference is given by the speed setter 7, and a current reference to the thyristor Leonard device 1 is outputted by the speed control circuit 8, which inputs the deviation from the speed detector 5 that detects the rotational speed of the load shaft. Further, a load sharing control device constituted by a frequency reference calculation circuit 9 that outputs a frequency reference to the inverter 3 from the output of the speed control circuit 8 and the rotational speed is shown surrounded by a dotted line.

The control operation of the frequency reference calculation circuit 9 is as shown in FIG.

This embodiment has the following effects.

0) Variable speed with DC motor and Cyrisk-Leonard device) 11! In order to promote system maintenance savings, it is possible to replace any number of DC motors and thyristor/Leonard devices with induction motors and inverters, reducing the economic burden. It doesn't happen sometimes.

(2) Load sharing operation control can be performed using a general-purpose inverter with constant V/F control.

〔Effect of the invention〕

According to the present invention, in equipment in which a thyristor-Leonard device-driven DC motor and a general-purpose inverter-driven induction motor are mechanically coupled to drive a load, it is possible to equally share the load between the DC motor and the induction motor. can.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a load sharing control device showing one embodiment of the present invention, and FIG. 2 is an explanatory diagram of a frequency reference generation circuit. 1... Thyristor Leonard device 2... DC motor 3... Inverter 4...
・Induction motor 5...Speed detector 6...Load
7...Speed setter 8...Speed control circuit 9...Frequency reference calculation circuit 21...Frequency converted rotation speed 22...Torque reference 23...Torque/speed curve of induction motor 24. ... Inverter operation standard frequency agent Patent attorney Nori Chika Ken Yutong Wang Hou Hongbun L
JFigure 1

Claims (1)

[Claims] A DC motor is driven by a thyristor Leonard device that controls current according to a current reference signal, and an inverter device is mechanically connected to the DC motor and outputs a voltage/frequency at a constant frequency according to an external frequency reference. In a load sharing control device comprising an induction motor, a speed setter that sets the speed of a load shaft, a speed detector that detects the speed of the load shaft, and a speed reference output from the speed setter and the speed detector. a speed control circuit that calculates a torque reference from the detected speed deviation of the load shaft and outputs a current reference to the thyristor Leonard device; a torque reference of the output of this speed control circuit; the actual speed; and the torque of the induction motor; A load sharing control device for an electric motor, comprising a frequency reference calculation circuit that outputs an operating frequency from a speed curve to the inverter device.