JPH0417034B2 - - Google Patents

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to an elevator control device using an inverter, and in particular, the present invention relates to an elevator control device using an inverter, and in particular, to prevent the elevator from suddenly stopping or becoming unusable while maximizing the use of inverter elements within the rated range. The present invention relates to an elevator control device that can avoid such problems.

[Prior art]

Generally, the speed control of an induction machine that raises and lowers an elevator is performed using an inverter because it consumes less power.

By the way, normally in this speed control circuit,
In order to prevent the current flowing through the inverter elements from exceeding the rating of the elements, the maximum value of the current command is limited by a current command limiting circuit, as is well known. If any of the inverter elements has an ON failure, the inverter's DC line will be short-circuited and a short-circuit current will flow through it.

Therefore, this short-circuit current causes secondary damage to the elements connected in series with the failed element, as well as the converter element and the contactor contacts of the power supply circuit. Therefore, in order to prevent this damage, an overcurrent detection circuit detects an overcurrent, cuts off the output of the base drive circuit of the inverter, and cuts off the short-circuit current.

By the way, in order to use the inverter element to the maximum within its rated range, it is necessary to make sure that the rated current of the element flows through the inverter element when the elevator is operated with the rated load loaded on the car. It is necessary to select the current capacity of the element.

However, when selecting elements in this way,
If a load higher than the rated load is loaded on the car, there is a risk that a current higher than the rated current will flow through the inverter elements, so the current command limiting circuit issues a current command to prevent the current higher than the rated current from flowing. It is restricted. The maximum value limit level of this current command limit circuit is normally set to a value approximately equal to the rated value of the element in order to use the element to the maximum within its rated range.

On the other hand, in the event that any of the inverter elements malfunctions, the overcurrent detection circuit must be shorted as soon as possible in order to prevent secondary damage to the elements connected in series with the failed element. It is necessary to detect the current, cut off the output of the base drive circuit of the inverter elements, turn off the normal elements, and cut off the short-circuit current.

However, the current detector and the overcurrent detection circuit have an operation delay, and in consideration of this operation delay, the detection level of the overcurrent detection circuit is set to a value slightly larger than the rated value of the element.

For this reason, conventionally, when an elevator is operated with a car loaded with more than the rated load and the current command limiting circuit is activated and a current close to the rated value of the element flows, the overcurrent detection circuit is also activated. There was a risk that the elevator would operate and cut off the output of the base drive circuit, causing the elevator to suddenly stop and become unusable.

[Summary of the Invention] The present invention has been made based on the above circumstances, and includes a current command limiting circuit that limits the maximum value of the current command to the inverter, and a current command limiting circuit that limits the maximum value of the current command to the inverter. and an overcurrent detection circuit that detects and cuts off the output of the inverter base drive circuit, and when the current command limiting circuit is activated, the output of the overcurrent detection circuit is disabled or the detection level of the overcurrent detection circuit is set. An elevator control device that prevents the overcurrent detection circuit from malfunctioning even if a current close to its rating flows through the inverter elements, thereby preventing the elevator from suddenly stopping or becoming unusable. is to provide.

[Embodiments of the invention]

Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is a block diagram showing the configuration of an elevator control device according to the present invention.

In the figure, 1 is a three-phase alternating current, 2 is a converter that converts the three-phase alternating current supplied through contact 3 of the contactor into direct current, 4 is a smoothing capacitor that smoothes the output from the converter 2, and 5 is the capacitor mentioned above. 4
An inverter that converts the DC input from the inverter into AC power using a transistor or the like, and controls and outputs the AC power; 6 is an induction motor that is rotationally driven by the AC power output from the inverter 5; 7;
is a regenerative power control device connected in parallel to the input side of the inverter 5, and by turning on a transistor 8, regenerative power is consumed by a regenerative power consumption resistor 9. Note that a main circuit 32 is configured by the inverter 5 and the induction motor 6.

Further, 10 is a net sheave of the hoist driven by the induction machine 6, 11 is a cage connected to one end of the main rope wound around the net sheave 10, and 12 is a suspension connected to one end of the main rope. Coupling weight, 13 is the above induction machine 6
14 is an adder for comparing and calculating the speed signal 13a with a speed command 15a issued from a well-known speed command generation circuit (not shown); 16 is an adder The adder 14 and the speed control circuit 16 constitute a speed feedback control section 30. 17
18 is an amplifier that inputs the torque current command 16a and issues a slip frequency command 17a; 18 is an adder that inputs this slip frequency 17a and the speed signal 13a, performs a comparison operation, and issues a frequency command 18a; 19 is an adder that outputs a frequency command 18a; A sine wave generating circuit 21 outputs a sine wave in response to input of a command 18a, and 21 is a sine wave 19a outputted from this circuit, the torque current command 16a, and an excitation current command 20a issued from an excitation current circuit (not shown). The current command generating circuit outputs a command 21a to the current command limiting circuit 22, and the current command limiting circuit 22 inputs the command 21a and outputs the command 21a as a current, based on the input command 21a. The current command 22b is outputted as a command 22b, and when the permissible range is exceeded, the current command 22b is limited to limit the maximum current flowing to the inverter 5.
It is designed to emit 2a.

Further, 23 is an overcurrent detection circuit that inputs a current value 24a from a current detector 24 provided on the DC input side of the inverter 5, and outputs an output signal 23a when this current value exceeds a set value. This circuit 23 is configured not to generate an output signal 23a even if the current value 24a from the detector 24 exceeds a set value when the command 22a is input.

Note that when the command 22a is input, the setting value of the overcurrent detection circuit 23 may be increased to increase the detection level. And 25
is the output signal 23a from the overcurrent detection circuit 23
26 is a current signal 28a from a current detector 28 provided on the output side of the inverter 5, and the current command limiting circuit 22.
an adder 27 for comparing the current command 22b from the
is a current control circuit which inputs the output 26a from the adder 26 and outputs an output signal 27a to the base drive circuit 25 based on the output 26a. Note that the current feedback control unit 3 is controlled by the current command generation circuit 21, the current command limit circuit 22, the overcurrent detection circuit 23, the base drive circuit 25, and the current limit circuit 27.
1 is configured.

Next, the operation of the above embodiment will be explained.

However, detailed description of well-known parts of elevator operation will be omitted.

First, alternating current from three-phase alternating current power supply 1 is rectified by converter 2 to become direct current, which is input to inverter 5 . This inverter 5 converts the input DC into AC power and outputs it, and rotates the induction motor 6 at a rotation speed corresponding to the output frequency.
The car 11 is moved up and down.

The speed signal 13a from the speed detector 18 and the speed command 15a are compared by the adder 14 and input to the speed control circuit 16, and the corresponding torque current command 16 is inputted to the speed control circuit 16.
Output a. The torque current command 16a is the amplifier 1
7 and outputs a slip frequency command 17a. This slip frequency command 17a and the speed signal 13a are input to an adder 18, and a frequency command 18a responsive to this is outputted to a sine wave generation circuit 19, and the sine wave generation circuit 19 to which this is input responds to it. A sine wave 19a is output toward the current command generation circuit 21.

This current command generation circuit 21 has the above-mentioned sine wave 19.
a, torque current command 16a and excitation current command 20
a is input, and a command 21a responding based on these signals is outputted to the current command limiting circuit 22.

Here, when the elevator car is operated with less than the rated load loaded, the current flowing to the inverter is less than the allowable value, so the current command limiting circuit 22 outputs the command 21a as it is as the current command 22b, and the command 22a is No output. Therefore, the overcurrent detection circuit 23 is operating effectively, and when the current detector 24 detects an overcurrent exceeding the set value due to an ON failure of an inverter element, the base drive circuit 2
5, and the base drive circuit 25 which receives this output cuts off its output. This disables conduction of the non-faulty inverter elements and cuts off the current, causing the elevator to suddenly stop and become unable to start.

On the other hand, when the elevator car is operated with a load exceeding the rated load, a current close to the permissible value will flow through the inverter, and in contrast to the above, the current command limiting circuit 22 will limit the current to a predetermined value. At the same time that the command 22b is issued, the command 22a is also output. The overcurrent detection circuit 23 that receives this current command 22a has its output signal 23a blocked or invalidated, so the output 25 of the base drive circuit 25 is
a will not be cut off, and therefore the elevator will not suddenly stop and become unusable.

Thereby, the inverter element can be used to the maximum extent within its rated range without rendering the elevator unusable.

Note that when any of the inverter elements turns ON while the current command limiting circuit 22 is operating, current cutoff becomes impossible; however, the current command limiting circuit 2
Normally, it is rare for 2 to operate, and at that time, the probability that an ON failure of the inverter element will occur is extremely low, so there is no particular problem in practice.

In the above embodiment, the overcurrent detection circuit 23 is prevented from generating an output when the current command limiting circuit 22 is operating; however, the present invention is not limited to this, and the current command limiting circuit 22 may be operating. When you are
The overcurrent detection level of the overcurrent detection circuit 23 may be increased by a predetermined value. In this case, not only the same effect as described above is produced, but even if an ON failure of an inverter element occurs while the current command limiting circuit is operating, other inverter elements can be protected.

〔Effect of the invention〕

As is clear from the above description, the present invention includes a current command limiting circuit that limits the maximum value of the current command to the inverter, and a current command limiting circuit that limits the maximum value of the current command to the inverter, and Equipped with an overcurrent detection circuit that cuts off the output of the drive circuit, the output of the overcurrent detection circuit is disabled or the detection level is raised when the maximum value of the current command is limited by the current command limiting circuit, so that the elevator Even when the car is operated with more than a certain load loaded, the output of the base drive circuit will not be cut off and the elevator will stop suddenly and become unusable. You can use it to the fullest without making it unusable.

[Brief explanation of drawings]

The figure is a block diagram showing the configuration of an elevator control device according to the present invention. 5... Inverter, 6... Induction motor, 22...
...Current command limit circuit, 23...Overcurrent detection circuit,
24... Current detector, 25... Base drive circuit,
30...Speed feedback control section, 31...Current feedback control section, 32...Main circuit, 35
...Inverter drive circuit.

Claims (1)

[Scope of Claims] 1. An elevator drive device including a speed feedback control section 30, a current feedback control section 31, and a main circuit 32, wherein the speed feedback control section 30 controls a speed command value 15a and a speed detector. 13 speed detection signal 13a
The main circuit 32 is for driving the induction motor 6 by the inverter 5 controlled by the inverter drive circuit 35, and the current feedback control section Reference numeral 31 includes a current command generation circuit 21, a current command limit circuit 22, a base drive circuit 25, an overcurrent detection circuit 23, and a current control circuit 27, and outputs a drive command signal 25a to the inverter 5. The current generating circuit 21 receives the torque command value signal 16a.
The current command limiting circuit 22 receives the current command signal 21a and the excitation command signal 20a and outputs the current command signal 21a.
is input and outputs a current command 22b, and when the current command signal 21a exceeds a predetermined value, the value of the current command 22b is limited to a predetermined value, and the current command 22a is output. The overcurrent detection circuit 23 is connected to the current detector 24 installed on the input side of the inverter 5 and the current command limiting circuit 22, and detects the current value 24a of the current detector 24 and a predetermined set value. When the inverter drive circuit 35 compares and determines that there is an overcurrent, it outputs a stop command signal for the base drive circuit 25, and when the current command 22a is input, it stops its operation. It controls the inverter 5, and operates based on the deviation between the current command 22b and the current signal 28a of the current detector 28 installed on the output side of the inverter 5, and generates a drive command signal 25.
1. An elevator driving device characterized in that it outputs a control signal for stopping the operation of an inverter 5 upon receiving an output signal 23a of an overcurrent detection circuit 23.