JPH11308881A - Over-voltage control apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To permit parallel layout of respective braking apparatuses, by outputting a conductive command to a self switching element under the logical SUM condition of the braking start signal of the Nth braking apparatus and the braking start signal of the first braking apparatus. SOLUTION: When two braking apparatuses are used, a parallel signal generator 1-4 is inserted between a setting comparator 1-2 and a switching element 1-3, and a parallel signal generator 2-4 is inserted between a setting comparator 2-2 and a switching element 2-3, to give the Br1 signal in the braking apparatus 1 side to the parallel signal generator 2-4 and the Br2 signal in the braking apparatus 2 side to the parallel signal generator 1-4. Moreover, when a DC voltage Vdc of a DC voltage circuit 6 of the inverter apparatus 4 exceeds the braking set level Vb1, since the braking start signal Br1 is given both to the parallel signal generators 1-4 and 2-4, these circuits output the commands Dr1, Dr2 to make conductive the switching element. As a result, the switching elements 1-3, 2-3 become conductive. Accordingly, parallel layout of the braking apparatuses may be realized.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to parallelization of braking devices of an inverter device. More specifically, the present invention relates to a time for driving a switching element inside each braking device without changing the braking device and peripheral circuits. The present invention relates to a uniform overvoltage suppression device.

[0002]

2. Description of the Related Art FIG. 4 shows a conventional example of an overvoltage suppression device for a DC voltage section of an inverter device when an induction motor is driven by the inverter device. In the figure, 4 is an inverter device, 5 is an induction motor, and 6 is a DC voltage portion of the input portion of the inverter device. When supplying power to the induction motor 5, the DC voltage Vdc is converted into a three-phase AC voltage by the inverter device 4, applied to the induction motor 5 and driven. On the other hand, when the induction motor 5 is used in the regenerative region, the DC voltage Vdc of the DC voltage unit 6 increases due to energy regenerated from the induction motor 5 via the inverter device 4. Then, V
A braking device is used to limit the rise of dc.

The number of parallel connections of the braking device is changed depending on the regenerative current capacity from the induction motor, the number of parallel connections of the inverter device and the induction motor, and FIG. 4 shows a case where two units are connected in parallel. 4, reference numerals 1 and 2 denote braking devices,
1, 2-1 are braking resistors, 1-2, 2-2 are setting comparators, 1-3, 2-3 are switching elements. next,
The operation of the braking device 1 will be described. The DC voltage Vdc is input to the setting comparator 1-2, and the braking setting level Vb1
Compare with Now, the DC voltage Vdc is equal to the braking set level V
When it exceeds b1, a braking start signal Br1 is output. When this signal is applied to the switching element 1-3, the switching element is turned on, and the braking resistor 1-
1. A current flows through the switching element 1-3, and the voltage of the DC voltage section is suppressed from becoming an overvoltage. Braking device 2
Needless to say, the same operation as in the braking device 1 is performed. By causing the braking resistor 1-1 and the braking resistor 2-1 to consume energy generated during the regenerative operation of the induction motor 5, an overvoltage of the DC voltage Vdc can be suppressed.

The above description is an example in which two braking devices are used. However, the braking devices having the same capacity are connected in parallel according to the regenerative current capacity from the induction motor, the number of inverter devices and the induction motor connected in parallel, and the like. By changing the number, the inefficiency of designing and manufacturing a large-capacity braking device in accordance with the regenerative energy in each case is avoided.

[0005]

However, in the prior art, the brake setting levels Vb1 and Vb2 inside the setting comparator 1-2 and the setting comparator 2-2 of the braking device 1 and the braking device 2, respectively, are usually Are not the same value, and some errors occur. Therefore, there is a time difference between the time when the braking start signals Br1 and Br2, which are the outputs of the setting comparators 1-2 and 2-2, are output, and the time when they disappear. As a result, a difference also occurs in the time during which the switching elements 1-3 and 2-3 and the braking resistors 1-1 and 2-1 of the braking device 1 and the braking device 2 operate.

The details will be described with reference to FIG. In FIG. 5, the braking set level Vb of the braking device 1 and the braking device 2
1 shows a case where there is an error between Vb2 and the braking set level Vb1 is lower than Vb2. In this case, the switching element 1-3 of the braking device 1 having the braking set level Vb1 turns on earlier and the off-operation is delayed than the switching element 2-3 of the braking device 2. Therefore, the duty of the switching element 1-3 and the braking resistor 1-1 is larger than that of the switching element 2-3 and the braking resistor 2-1.
The service life is shortened as compared with.

Further, if the error between the braking set levels Vb1 and Vb2 is large, there is almost no chance that the braking device 2 having the high braking set level Vb2 will operate, and there may be little meaning in providing two brake units. As a method for solving such a problem, it is conceivable to provide a setting comparator commonly on the inverter device 4 side. However, the inverter device is often used for applications in which the same model is not used in the regeneration area. Has a setting comparator which is not necessary at all. That is, since it is disadvantageous in terms of the total cost to provide a setting comparator in the inverter device as a standard, the setting comparator is generally provided on the brake device side that is optionally used.

The present invention is an improvement of the above-mentioned conventional technique, and sets the braking set levels Vb1 and Vb of the braking device 1 and the braking device 2, respectively.
2 is to provide a braking device that can operate the switching elements for the same time even when there is an error, and that can be parallelized without changing settings such as wiring change of each braking device.

[0009]

Means for achieving the object is to output a braking start signal when a voltage value of a DC voltage source for supplying power to an inverter for driving an induction motor exceeds a braking set level. A setting comparator, a series circuit of a switching element and a braking resistor connected to both ends of a DC voltage source and conducting by the braking start signal, and a braking device including the series circuit of the setting comparator, the switching element, and the braking resistor described above. Are connected in parallel in N units, the first to (N-1) th braking devices are M
A parallel signal generator that outputs a conduction command to its own switching element under the condition of the logical OR of the braking start signal of the (1 ≦ M ≦ N−1) th braking device and the braking start signal of the (M + 1) th braking device And a parallel signal generator that outputs a conduction command to its own switching element under the condition of a logical sum of the braking start signal of the Nth braking device and the braking start signal of the first braking device. .

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a block diagram showing one embodiment of the present invention using N = 2, M = 1, that is, two braking devices. FIG. 2 is a block diagram showing N = 3, M = 2, that is, a book using three braking devices. FIG. 3 is a block diagram showing an embodiment of the invention, and FIG. 3 is a diagram showing the operation of the embodiment. Hereinafter, FIG. 1 will be described. In the figure, reference numerals 1-4 and 2-4 denote parallel signal generators. The difference from FIG. 4 is that the setting comparator 1-2 and the switching element 1
-3, a parallel signal generator 2-4 is inserted between the setting comparator 2-2 and the switching element 2-3. The point is that the signal is also supplied to the parallel signal generator 2-4, and the Br2 signal on the braking device 2 side is also supplied to the parallel signal generator 1-4. In addition,
Portions denoted by the same reference numerals as those in FIG. 4 indicate the same function and the same configuration.

With this configuration, when the DC voltage Vdc of the DC voltage section 6 of the inverter device 4 exceeds the braking set level Vb1, the braking start signal Br1 is sent to both the parallel signal generators 1-4 and 2-4. As a result, the parallel signal generators 1-4 and 2-4 both output the switching element conduction commands Dr1 and Dr2, and the switching elements 1-3 and 2-3 are both turned on. Similarly, when the DC voltage Vdc exceeds the braking set level Vb2, the braking start signal Br2 is supplied to both the parallel signal generators 1-4 and 2-4, so that the parallel signal generators 1-4 and 2-4 are both switched. The device outputs the conduction commands Dr1 and Dr2 of the devices, and the switching devices 1-3 and 2-3 become conductive.

Hereinafter, the present invention will be described in detail with reference to FIG.
In FIG. 3, there is an error in the braking set levels Vb1 and Vb2 of the braking device 1 and the braking device 2, and the braking set level Vb
When 1 is lower than Vb2, the drive time T1, which is the ON time of the braking start signal Br1, is longer than the drive time T2, which is the ON time of the braking start signal Br2. However, in the parallel signal generator 1-4 inside the braking device 1, when either the braking start signal Br1 of the own braking device or the braking start signal Br2 of the other braking device is input, the conduction command Dr1 is switched under the condition of the logical sum. Output to element 1-3,
Similarly, in the parallel signal generator 2-4 inside the braking device 2, when either one of the braking start signal Br2 of the own device and the braking start signal Br1 of the other braking device is input, the condition of the logical sum is obtained. To output the conduction command Dr2 to the switching element 2-3.
Thus, even when there is an error between the braking set levels Vb1 and Vb2 of the braking device 1 and the braking device 2, the switching elements 1-3 and 2-3 are operated in the same driving time. Therefore, there is no difference between the conduction times of the switching elements, and the responsibilities of the switching element and the braking resistor become equal.

Similarly, when there are three braking devices as shown in FIG. 2, the braking device 1 can control its own braking start signal Br1.
And the braking command signal Br3 of the braking device 3 as an input, the parallel signal generator 1-4 generates a conduction command Dr1, and the braking device 2 outputs its own braking start signal Br2 and the braking start signal Br1 of the braking device 1. As an input, the parallel signal generator 2-4 generates the conduction command Dr2, and the braking device 3 similarly generates its own braking start signal Br3 and the braking start signal Br2 of the braking device 2.
, The conduction command Dr3 is output from the parallel signal generator 3-4.
Can be generated, and the duty can be prevented from being concentrated on the switching element and the braking resistor of one braking device. In the above description, a case where up to three units are connected in parallel has been described. However, it goes without saying that the present invention can be applied to a case where four or more units are connected.

[0014]

As is apparent from the above description, according to the present invention, even if there is an error in the braking set level of each braking device, it is possible to prevent responsibilities from being concentrated on specific switching elements and braking resistors. be able to. Further, for each braking device, there is an advantage that the braking devices can be parallelized only by preparing the wiring for connecting the braking devices without changing the setting such as a wiring change in the paralleling, or a plurality of braking devices. Paralleling of the braking devices is also possible.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an embodiment in which two braking devices are connected in parallel according to the present invention.

FIG. 2 is a block diagram showing an embodiment in which three braking devices are connected in parallel according to the present invention.

FIG. 3 is a diagram illustrating an operation of the embodiment.

FIG. 4 is a block diagram showing the contents of a conventional technique.

FIG. 5 is a block diagram showing the operation of the conventional technique.

[Explanation of symbols]

1, 2, 3 Braking device 1-1, 2-1 Braking resistance 1-2, 2-2 Setting comparator 1-3, 2-3 Switching element 1-4, 2-4 Parallel signal generator 4 Inverter device 5 Induction motor 6 DC voltage part Vdc DC voltage Vb1, Vb2 Braking set level Br1, Br2, Br3 Braking start signal Dr1, Dr2, Dr3 Conduction command T1 Drive time of brake start signal Br1 T2 Drive time of brake start signal Br2 T Conduction command Dr1 , Dr2 drive time

Claims (1)

[Claims] 1. A setting comparator for outputting a braking start signal when a voltage value of a DC voltage source for supplying power to an inverter for driving an induction motor exceeds a braking set level, the setting comparator being connected to both ends of the DC voltage source, In a series circuit of a switching element and a braking resistor that are turned on by a braking start signal, and in an overvoltage suppression device configured by connecting N braking devices in parallel with each other, the first to (N-1) th braking (N is a natural number) The device switches its own switching element under the condition of the logical sum of the braking start signal of the M (1 ≦ M ≦ N−1) th (M is a natural number) braking device and the braking start signal of the (M + 1) th braking device. A parallel signal generator for outputting a conduction command is provided. The braking start signal of the Nth braking device outputs a conduction command to its own switching element under a logical OR condition with the braking start signal of the first braking device. Parallel An overvoltage suppression device comprising a signal generator.