JPS58107089A - Detector for trouble of inverter - Google Patents

Abstract

PURPOSE:To detect trouble rapidly of the titled device by using output by the AND of the output signals of a slip detector and the output signals of a current detector as trouble signals. CONSTITUTION:The output of a rectifier 1 is inputted to the inverter 3 through a DC reactor 2, and an induction motor 4 is driven by the output of the inverter 3. Difference with inverter output frequency 11 is detected in the output of a speed detector 5 connected to the motor 4, and the output of the detector 5 is inputted to a comparator 23. The output of the comparator 23 is inputted at one input terminal of an AND circuit 24 while the output of the current detector 21 mounted at the input side of the rectifier 1 is inputted to a comparator 22 and the output is inputted at the other input terminal of the AND circuit 24.

Description

[Detailed description of the invention] The present invention relates to an inverter failure detection device.

A conventional inverter failure detection device was constructed as shown in FIG. In the figure, the output of a rectifier 1 is input to an inverter 3 via a DC reactor 2, and there is a circuit for driving, for example, an induction motor 4 by the output of the inverter 3.

a first flow discharge device 11 attached to the input side of the rectifier l;
The output of 21 is input to a comparator 22, and the output of this comparator a22 is input to one input terminal of an AND circuit 24 via a delay m circuit 26t-. On the other hand, the output of the inverter 3 is input to the comparator #r23 via the voltage detector 25, and the output of this comparator 23 is input to the AND circuit 24.
It is designed to be input to other input terminals of the .

In such a configuration, if the inverter fails, the input IIL current increases and the output voltage decreases. Therefore, the comparators 22 and 23 check whether the human power current and the output voltage are above a predetermined value or below Fvc, respectively. It is determined and taken out as the output total failure signal of the ANDIII circuit 24.

However, with the above-mentioned configuration, since the input current increases and the output voltage decreases instantaneously when the rust conductive excitation rod 4 is overloaded, it is not appropriate to extract a failure signal even under such conditions. , input area JIIMIK is delay circuit 2
6 to provide a time delay to the input of the AND circuit 24. Therefore, even when the inverter actually fails, there is a drawback that there is a time delay in extracting the failure signal.

The object of the present invention was made based on the above circumstances.
Therefore, it is an object of the present invention to provide an inverter failure detection device that can quickly detect failures.

In order to achieve these objectives, the present invention includes a rectifier section that converts alternating current to direct current, a rounded smoothing circuit section that smoothes direct current, and an inverter section that converts direct current to 9:tIlt. The 1tfL type inverter device includes a speed detection circuit that detects that the difference between the output of the speed detector that detects the rotational speed of the induction motor that is the load and the inverter output frequency is equal to or greater than a predetermined value; and a current detection circuit that detects that the input current is greater than or equal to a predetermined value, and the output from the logical product of the output signal of the above-mentioned Beshi detector and the output signal of the current detector is set as failure No. 1d. .

The present invention will be explained in detail below using Examples.

FIG. 2 is a circuit diagram showing an embodiment of a failure detection device for a droop type inverter according to the present invention. 1! The output of the flow device 1 is inputted to an inverter 3 via a DC reactor 2, and the output of this inverter 3 drives an induction motor number. The induction motor 4 is equipped with a speed detector 5.
is connected, and the output of this speed detector 5 is input to a comparator 923 after taking the difference from the inverter output frequency 11. Taking the difference from the inverter output frequency a11 is the ninth step in detecting the slip of the motor. Furthermore, the output of the comparator 23 is input to one input terminal of an AND circuit 24. On the other hand, the adjustment f
The output of the current detector fi21 attached to the input side of the lt device 1 is input to a ratio f device 22, and the output of this comparator 22 is input to the other input terminal of the ANDII2 circuit 24.

Here, details of the inverter control circuit will be explained using FIG. 3. In the same figure, there is an inverter speed signal generation circuit 30, and this inverter speed signal generation circuit 3
The frequency signal that is the output of
is designed to be controlled.

First, the frequency signal from the inverter speed signal generation circuit 30 is sent to a voltage/frequency converter, 61. <Russ distributor 3
7t-, a control rectifying element in the inverter 3 is ignited, thereby controlling the frequency.

Furthermore, the output of the current detection device 21 is transmitted to the signal conversion circuit 31.
The signal is input to the signal converter circuit 31, which converts the level to R, and constitutes a feedback circuit of the current controller 34. Further, the output of the #-marked I/verter 3 is inputted to the signal conversion circuit 32 via the voltage detector 25, and the level is converted by the signal conversion circuit 32, thereby forming a feedback circuit of the voltage control @33. .

The inverter output frequency 11 is taken out from the output of the inverter speed signal generation circuit 30, and this output is input to the comparator 23. This comparator 23 includes an operational amplifier OP1 and a resistor RI-R.
4, a diode DI, and a variable resistor Vml, and the inverter output frequency 11 is inputted to one terminal of the operational amplifier OPs via the resistor R1.

The output of the speed detector 5 is inputted via the signal converter 38 to one terminal of the operational amplifier OP1 via the resistor R1. In addition, in the comparator 23, a diode DI is connected between one terminal of the operational amplifier *OPs and the output terminal, and the diode DI is connected to the ground via a resistor R@ and a variable resistor Vat. The terminal is grounded via a resistor R4.

Here, by adjusting the variable resistor Vml, the deviation detection level between the rotation speed and the inverter frequency can be varied.

The current value of the output from the current detection device 21 via the current transformer 31 is determined by a comparator 22 composed of an operational amplifier OPm, a resistor Ri-Ry, a diode DI, and seven variable resistors. It is possible to detect that the level is above a predetermined level. The current detection level can be adjusted using VRs.

The blade signal from these ratios #lI22.23 is AND
A logical product is performed in the circuit 24, and an inverter failure signal 1- is generated, so that a system protection circuit (not shown) is immediately activated.

The inverter failure detection device configured in this way uses the inverter output frequency for rounding of failure detection, detects when the deviation between this output frequency and the load motor rotation speed exceeds a predetermined value, and additionally detects the input By detecting that IIEfIL is greater than or equal to a predetermined value, 1. Since a failure of the inverter is detected, there is no need to provide an A extension circuit, and therefore failure can be detected quickly.

In addition, in this example, the signal level comparison is performed using analog quantities, but a means for detecting the inverter frequency signal and motor rotation speed signal as pulse signals and calculating the deviation between the two by digital calculation is also provided. It goes without saying that the same effect can be obtained by using the same method.

As is clear from the above description, according to the inverter failure detection device according to the present invention, failures can be detected quickly.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram showing an example of a conventional inverter failure detection circuit, FIG. 2 is a schematic circuit diagram showing an embodiment of an inverter failure detection device according to the present invention, and FIG. 3 is an inverter failure detection circuit according to the present invention. FIG. 2 is a detailed circuit diagram showing one embodiment of a detection device. l... Rectifier, 3... Inverter, 4... Electric II
h Iso, 5... Speed detector, 11... Inverter output frequency, 22° 23... Comparator, 24... AND circuit, 12... Fault signal Figure 1 Figure 2 Figure 3

Claims (1)

[Claims] 1. In a current source inverter device consisting of a pot current part for converting alternating current into direct current, a smoothing circuit part for smoothing t[ft, and an inverter part for converting direct current to alternating current,
A speed detection circuit detects that the difference between the output of the speed detector that detects the rotation speed of the induction motor (L#) and the inverter output frequency is greater than a predetermined value, and the input current of the converter is greater than or equal to the predetermined value. An inverter comprising: a voltage fL detection circuit for detecting a certain occurrence, and an output obtained by logically multiplying the output signal of the smooth output device and the output signal of the W*detector as a failure signal. failure detection device.