JPS60255090A - Scherbius system - Google Patents

Abstract

PURPOSE:To maintain a motor speed constant even when the frequency of a power source varies by taking frequency difference between a power source frequency and the slip frequency of the motor, and using it as a speed signal for comparing it with a set speed signal of a speed setter. CONSTITUTION:The frequency fc of a power source system 1 is detected by a power source frequency detector 18, and the secondary slip frequency fs is detected by a slip frequency detector 11, the signal fs and the signal fc are added by an adder 19 to obtain a frequency difference signal (fc-fs). This output is applied together with the set speed signal of a speed setter 12 to a speed controller 13 as a speed signal, and an inverter 10 is controlled by the output to automatically follow up the speed set by the setter 12 even if the power source frequency varies.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a Cerbius system that allows highly accurate motor speed to be obtained even without a speed sensor in an electric motor (hereinafter referred to as a motor).

[Technical background of the invention and its problems] Generally, when configuring a Serbius system, a motor speed sensor such as a pulse generator or a tacho generator is required for the wound motor, but the installation space is small and it is difficult to install the speed sensor. If this is not possible, the secondary slip frequency of the wound motor is used as the motor speed signal for convenience. However, in this case, even if the frequency of the power source changes and the speed of the motor changes, the slip frequency of the motor does not change, resulting in a problem that a difference occurs between the actual speed of the motor and the preset speed.

Hereinafter, such a conventional Servius system without a speed sensor will be explained in detail using FIG. 1. This Servius system includes a breaker 3 that separates the power supply system 1 and the wound motor 2, a Servius device 4 that controls the secondary slip power of the winding motor 2 to perform speed control, and a Servius device 4 that controls the secondary slip power of the winding motor 2 to control the speed. It is composed of an inverter transformer 5 that returns the power to the inverter transformer 5, and a breaker 6 that disconnects the inverter transformer 5 from the power supply system 1. Further, the Servius device 4 is configured as follows. In other words, the secondary slip power of the wound motor 2 is given to the rectifier 8 which converts AC power into DC power via the contactor 7, and the output is given to the rectifier 8 which converts the AC power into DC power via the smoothing DC reactor 9. Inverter 1 to convert
0, and the output of the inverter 10 is further applied to the power supply system 1 via an inverter transformer 5 and a breaker 6 that converts it into a power supply system voltage. On the other hand, the secondary slip frequency of the wound motor 2 is detected by the slip frequency detector 11 and inputted to the speed control circuit 13 together with the set speed signal from the speed setter 12, and the output of the speed control circuit 13 is controlled by the current control circuit. The signal is input to the circuit 14, and further input to the phase control circuit 15, whose output is input to the inverter 10 for phase control. Note that the control power source for this Serbius device 4 is inputted from the power supply system 1 to the control transformer 17 via the circuit breaker 16, and the output of the control transformer 17 is used.

In this configuration, in order to satisfy the motor speed set by the speed setter 12, the secondary slip frequency fs of the wound motor 2 is input to the speed control circuit 13 together with the set speed signal from the speed setter 12, and the speed is set. The output of the speed control circuit 13 is used as a speed signal, and the phase of the inverter 10 is controlled via the current control circuit 14 and the phase control circuit 15. , a predetermined speed of the wound motor 2 is obtained.

However, in such a conventional Servius system, when the frequency of the power supply system 1 changes due to a decrease in the generator output frequency due to overload, the actual motor speed changes, but since the speed is controlled using the slip frequency. The slip frequency does not change, the Servius device 4 sends out the same output, and does not sense that the speed of the wound motor 2 has changed.
There is a problem that the difference between the speed set by the speed setter 12 and the actual speed of the wound motor 2 becomes large, making it impossible to obtain a predetermined motor speed.

[Purpose of the Invention] The present invention was made in order to eliminate the above-mentioned problems, and its purpose is to improve the Cerbius motor speed, which is capable of keeping the motor speed constant even when the frequency of the power supply system fluctuates. The goal is to provide a system.

[Summary of the Invention] In order to achieve the above object, the present invention provides a frequency difference between the power supply frequency and the motor threshold frequency so that the motor speed remains at a predetermined speed even when the frequency of the power supply system fluctuates. The present invention is characterized in that the motor speed is corrected by controlling the inverter by giving this as a speed signal to be compared with a set speed signal of a speed setting device.

[Embodiment of the Invention] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 2 shows an example of the configuration of the Servius system according to the present invention. The same parts as those in FIG. In other words, Fig. 2 shows the frequency fc of power supply system 1 in Fig. 1.
an adder 19 which adds the output of the detector 18 and the output fs of the slip frequency detector 11 to obtain an output difference ic −fs );
This output signal <1a-fs) is supplied to the speed control circuit 13 as a speed signal to be compared with the set speed signal.

In such a system, the power supply frequency detector 18 determines the frequency (C) of the power supply system 1, and the slip frequency detector 11 determines the secondary slip frequency J of the wound motor 2.
s is detected, and the adder 19 adds the slip frequency signal is and the power supply frequency signal fc to obtain a frequency difference signal <fc −1s >, and the output thereof is used for speed control together with the set speed signal of the speed setter 12. The speed signal is given to the circuit 13 as a speed signal, and the inverter 10 is controlled by the output, so that even if power frequency fluctuation occurs, the speed setter 1
It becomes possible to automatically follow the speed set in step 2.

As described above, according to the present embodiment, the speed of the wound motor 2 can be kept constant without departing from the speed set by the speed setting device 12 even though the *m frequency changes and the motor speed changes. Servius system can be obtained.

It should be noted that the present invention is not limited to the above embodiments, and for example, as shown in FIG.
fc2) 2 lines of electricity 1t! Power is supplied from 1.1' to operate motor 2, and the secondary slip power is transferred to Servius device 4A.
In the Servius system, which returns slip power to each power supply system 1.1', the power supply frequency is fc 1
=so+-+z, even when JC2=60Hz, it is possible to keep the motor speed constant by applying the present invention. In addition, in the figure, 21 to 24 are contactors.

[Effects of the Invention] As described above, according to the present invention, a highly accurate Cerbius system that can keep the motor speed constant even when the frequency of the power supply system fluctuates can be provided.

[Brief explanation of drawings]

Figure 1 is a configuration diagram showing the conventional Servius system, Figure 2
The figure is a block diagram showing one embodiment of the present invention, and FIG. 3 is a block diagram showing another embodiment of the present invention. 1.1'...'R power supply system 2...Wound motor, 3
... Breaker, 4,4A ... Servius device, 5.
... Inverter transformer, 6... Breaker, 7.21
~24... Contactor, 8... Rectifier, 9... DC reactor, 10... Inverter, 11... Slip frequency detector, 12... Speed setter, 13... Speed control circuit , 14... Current control circuit, 15... Phase control circuit, 16... Breaker, 17... Control transformer, 18... Power frequency detector, 19... Adder. Applicant's agent Patent attorney Takehiko Suzue Figure 1 Figure 3

Claims (1)

[Claims] The secondary slip frequency of the wound motor connected to the power supply system is used as a speed signal, this speed signal is compared with a set speed signal, and the secondary slip power of the wound motor is controlled based on the comparison result to determine the speed. In the Serbius system which performs control and returns the slip power to the power supply system, there is provided a power supply frequency detection means for detecting the frequency of the power supply system, and a power supply frequency detected by the power supply frequency detection means and the winding wire. A Servius system comprising: arithmetic means for calculating a difference with a secondary slip frequency of an electric motor, and a frequency difference signal that is an output of the arithmetic means is used as the speed signal.