JPH02101970A - Snubber loss reducing circuit - Google Patents

Abstract

PURPOSE:To reduce the snubber loss and to improve the efficiency by temporarily storing snubber energy in a reactor and returning to a main circuit as a chopper circuit performs boosting operation. CONSTITUTION:A capacitor 3 connected in series with a first switching element 2 is connected to the anode of a self-extinguish element GTO1, with the other end of the capacitor 3 connected to the cathode of the GTO1, and a diode 4 connected in series with a reactor 5 is connected to the joint of the element 2 and the capacitor 3. When the other end of the reactor 5 is connected to the anode of the GTO1 and two snubber circuits comprising diodes 6 are connected in parallel with the capacitor 3, snubber loss can be reduced.

Description

Detailed Description of the Invention [Object of the Invention] (Industrial Field of Application) The present invention relates to a snubber circuit for a chopper circuit using a self-extinguishing element such as a gate turn-off thyristor (GTO), and particularly to a snubber circuit for a chopper circuit using a self-extinguishing element such as a gate turn-off thyristor (GTO). The present invention relates to a snubber loss reduction circuit characterized by reducing snubber loss by regenerating energy to the main circuit during chopper circuit operation.

(Prior Art) A device consisting of a boost chopper and an inverter has various advantages and has been widely adopted as a source device such as CVCF (constant voltage constant frequency). In order to improve voltage control transient characteristics, the boost chopper control section is usually on/off controlled at a frequency that is 10 to 10 times higher than the inverter's output frequency, and the snubber loss is proportional to the frequency, so the loss is This increases significantly compared to the snubber loss of the inverter component elements.

FIG. 10 shows an example of a conventional step-up chopper circuit, in which 11 is a DC power supply, 1.2 is a DC reactor, 13 is GTo, 14 is a diode, 15 is a smoothing capacitor, and 6
indicates an inverter.

GTo3 has a snubber circuit (surge absorption circuit),
A diode 18 and a resistor 17 are connected in parallel, and a capacitor 19 is connected in series.

The operation of the conventional step-up chopper circuit having such a configuration will be explained with reference to the time chart shown in FIG. (
(a) is the on/off control signal of GTol3, and (b) is the DC current flowing through the DC reactor 12. The ON and OFF energies of GTol 3 are variably controlled from time T1 to T2. In the case of a duty cycle where the DC current increases, the GTO 13 is turned on for a time T2, the DC current increases as shown by ■, and then the GTol 3 is turned off to repeat a series of operations in which the DC current decreases at a constant attenuation rate, releasing DC energy and reducing the capacitor. 15 is higher than the voltage of the DC power supply 1. Also, the on-time of the chopper becomes the minimum, and GTOl 3 becomes the time T
When the circuit is turned on only during , the DC current increases and decreases as shown in (■) is repeated to perform a boost operation.

(Problem to be Solved by the Invention) In the chopper circuit configured by increasing the chipper frequency in order to improve voltage control transient characteristics, the snubber circuit is only configured by a resistor 17, a diode 18, and a capacitor 19. There was a problem in that the snubber loss of the GTO for Chi-Five brim increased, which was not desirable.

An object of the present invention is to provide a snubber loss reduction circuit that can reduce snubber loss and thereby contribute to improving the efficiency of the device.

[Structure of the Invention] (Means for Solving the Problems) In order to achieve the above object, the present invention includes a first switching element whose anode is connected to the anode of the self-arc-extinguishing element; a capacitor in which a switching element and one end of the capacitor are connected in series; the other end of the capacitor is connected to the cathode of the self-extinguishing element, and the anode of the capacitor is connected to the connection point of the first switching element and the capacitor. A diode, the cathode of this diode is connected to a reactor, the other end of this reactor is connected to the anode of the self-arc-extinguishing element, and the anode is connected to both ends of the capacitor, and one end is connected to the cathode of the self-arc-extinguishing element. The present invention is characterized in that two sets of snubber circuits connected in parallel with the polarities to be connected are provided in parallel, and the plurality of switching elements are alternately energized to operate the circuit.

Further, in order to achieve the above object, the present invention includes a first diode whose anode is connected to the anode of the self-extinguishing element, and a first diode and a first capacitor connected in series. A first switching element whose anode is connected to the connection point, one end of the first switching element and the first reactor are connected in series, and the other end of the first reactor is connected to a DC power source or A first circuit is connected to an intermediate potential of the connected capacitors, a second capacitor is connected to the anode of the self-extinguishing element, and the other end of the second capacitor is connected to the anode of the second diode. , a second switching element whose cathode is connected to the cathode of the self-extinguishing element, and whose cathode is connected to the connection point between the second diode and the second capacitor; A second reactor is connected in series with the second switching element, and the other end of the second reactor has a DC power supply or a second circuit connected to an intermediate potential of the series-connected capacitors, This is characterized in that the switching elements of the first circuit and the second circuit are alternately energized to operate the circuit.

Furthermore, in order to achieve the above object, the present invention connects one end of the first capacitor to the anode of the first self-extinguishing element, and connects the other end of the first capacitor to the anode of the first diode. The cathode of the first diode is connected to the cathode of the first self-extinguishing element, and the cathode of the first switching element is connected to the connection point of the first capacitor and the anode of the first diode. , the anode of the first switching element is connected to one end of the first reactor, the other end of the first reactor is connected to the intermediate potential of the DC power supply or capacitor connected in series, and the anode of the first switching element is connected to one end of the first reactor. The anode of the self-arc-extinguishing element is connected to the positive electrode of the DC power source or the capacitor to form a closed circuit, and the anode of the second self-arc-extinguishing element is connected to the anode of the second diode. the anode of the second diode is connected, the cathode of the second diode is connected to one end of the second capacitor, the other end of the second capacitor is connected to the cathode of the self-extinguishing element; An anode of a second switching element is connected to the connection point between the cathode and the second capacitor, a second reactor is connected to the cathode of the second switching element, and the other end of the second reactor is connected to the second capacitor. a second circuit connected to an intermediate potential of the DC power supplies or capacitors connected in series, and connecting the cathode of the self-extinguishing element to the negative pole of the DC power supply or the capacitor to form a closed circuit; A first circuit and a second circuit connect the cathode of the first self-arc-extinguishing element and the anode of the second self-arc-extinguishing element, and are connected in series and antiparallel to the first self-arc-extinguishing element. A third diode is connected to the second diode.
The circuit has a set of circuits in which a fourth diode is connected in antiparallel to a self-extinguishing element of the first circuit, and there is at least one set of circuits having the same configuration as the first set of circuits. A third electrode is connected to either the anode of the self-arc-extinguishing element and the positive electrode of the DC power source or the capacitor, or the cathode of the second self-arc-extinguishing element of the second circuit and the negative electrode of the DC power source or the capacitor.
A reactor is connected to the reactor.

(Function) Since the present invention is configured as described above, the snubber energy can be stored in the accelerator which plays a role and regenerated to the main circuit along with the boosting operation of the chopper circuit, as compared to the conventional snubber circuit. Snubber loss can be reduced.

(Example) Hereinafter, an example of the present invention will be described with reference to the drawings. The same parts as those in FIG.

FIG. 1 is a circuit diagram showing a first embodiment of the present invention. Figure 1 shows two sets of snubber circuits (surge absorption circuits) with the same configuration.
It consists of One set of snubber circuits (on the right side of the figure) is configured as follows. That is, a switching element such as a thyristor 2 whose anode is connected to the anode of a self-extinguishing element such as GTOI, a snubber capacitor 3 connected in series with this thyristor 2, and the other end of this capacitor 3 connected to the cathode of GTOI. A diode 4 is connected, and its anode is connected to the connection point between the thyristor 2 and the capacitor 3, and the cathode of this diode 4 is connected to a reactor 5, and the other end of this reactor 5 is connected to the GTOl.
A diode 6 is connected in parallel to both ends of the capacitor 3 so that its anode is connected to the cathode of the element. Similarly, other snubber circuits include: thyristor 2 a s snubber capacitor 3 a s thyristor 4 a s diode 5 a, 6 a
It is composed of. Note that the diodes 4 and 4a.

6.6a are all for current circulation. The thyristors 2 and 2a described above are alternately energized to operate the circuit.

The operation of the circuit shown in FIG. 1 will be explained below with reference to FIGS. 2 and 3. FIG. 2 is a time chart for explaining the operation shown in FIG.
Since the value changes up to 2, two cases of MIN and MAX are shown by arrows. FIG. 2 (a) shows the ON/OFF control signal of GTOl, (b) shows the voltage of the capacitor 3a,
(C) is the current of reactor 5a, (d) is the capacitor 3
(e) shows the current of the reactor 5, (f) shows the gate signal of the thyristor 2a, and (g) shows the gate signal of the thyristor 2.

The capacitor 3a is connected at time tl' or at time t2''
When GTOl turns off, it is charged through the thyristor 2a as shown by the arrow in the figure and held constant.

FIG. 3 shows a typical operating mode of this circuit in the discharge mode of the capacitor 3a. From time t0 to t2, the GTOl is turned on, the current from the DC power supply 1 and the DC reactor 12, and the charge of the capacitor 3a are transferred to the reactor 5a, and the current of the reactor 5a circulates (1),
(If chopper duty is MIN, time t, %
j2 mode disappears), time t2 to t is GTOI
is turned off, the energy stored in the DC reactor 12 and the reactor 5a becomes two modes: a mode (n) in which the capacitor 15 is charged via the diode 14. With the above operation, the energy of the capacitor 3a is transferred to the reactor 5a, and is further regenerated to the capacitor 15. As described above, the charge of the capacitor 3a is
When the GTOl is turned off, a charging mode occurs every other time, and a mode in which the snubber energy of the capacitor 3a is transferred to the reactor 5a and is regenerated to the capacitor 15 occurs every other time. This is because if the capacitor 3a is charged before the energy of the snubber capacitor 3a transferred to the reactor 5a is regenerated to the capacitor 15, the energy of the reactor 5a will circulate through the thyristor 2a. For this reason, thyristor 2, reactor 5,
An identical second circuit of capacitor 3, diode 4.6 and thyristor 2a is required.

Reactor 5a, capacitor 3a, diodes 4a, 6
A continuous snubber energy regeneration operation can be achieved by supplementing the operation of the first circuit consisting of a every other time. Therefore, as shown in FIG. 2, the thyristors 2 and 28 are alternately energized, and the first circuit and the second circuit alternately repeat the snubber circuit operation and the regeneration operation, resulting in a mutually complementary mode.

FIG. 4 shows a second embodiment of the invention. Components that are the same as those in FIG. 1 are given the same reference numerals, and their explanation will be omitted. A diode 7 is added, and the smoothing capacitor 10 is divided into two parts 10a and 10b, which are connected in series. Specifically, it is configured as follows.

A diode 4a whose anode is connected to the anode of a self-extinguishing element such as GTOl, and a switching element such as Cyrisk 2a where the diode 4a and a capacitor 3a are connected in series and whose anode is connected to this connection point.
sThis thyristor 2a and one end of a reactor 5a are connected in series, and the other end of this reactor 5a is connected to an inverter 1.
A capacitor 3 is connected to the anode of the GTOl, and the other end of the capacitor 3 is connected to the anode of the diode 4. A switching element, such as a thyristor switching element 2, whose cathode is connected to the cathode of the GTOl, and whose cathode is connected to a connection point between the diode 4 and the capacitor 3, a reactor 5 connected in series with the thyristor 2, and a reactor 5 connected in series with the thyristor 2. The other end of 5 has an inverter 16 or a second circuit connected to the intermediate potential of the capacitors 15a and 15b connected in series, and the thyristors 2 and 2a of the first circuit and the second circuit
are alternately energized to operate the circuit.

FIG. 5 is a time chart for explaining the operation of the circuit shown in FIG. 4. Similar to FIG. 2, the arrows indicate two cases in which the on-duty of GTO1 is MAX and MIN. (a) is the gate signal of GTOl, (b) is the gate signal of thyristor 2a, (C) is the gate signal of thyristor 2, (d) is the voltage of capacitor 3a, (e) is the voltage of capacitor 3, (f ) is the current of the reactor 5a, (
g) is the current of the reactor 5.

FIG. 6 is a diagram illustrating the operation mode of FIG. 4. Time t. When the thyristor 2a is turned on, the capacitor 3a
The electric charge is discharged and regenerated by causing a resonance current to flow through the thyristor 2a and the reactor 5 to the capacitor 15b.

If the charge of capacitor 3a is configured only in capacitor 15b, the voltages of capacitors 15a and 15b will be unbalanced and regeneration will not be possible. Therefore, a second circuit in which capacitor 3 and diode 4 are connected in reverse is provided to Charge is passed through reactor 5, thyristor 2, and capacitor 1.
As shown in FIG. 5, the thyristor 2a and the thyristor 2 are configured to be alternately energized in synchronization with the GTOl. With this configuration, stable snubber energy regeneration can be performed, which can contribute to improving the efficiency of the device.

FIG. 7 is a circuit diagram showing a third embodiment of the present invention (an example applied to an inverter snubber circuit), in which the rectifier 22,
Reactor 23, filter capacitor 24.24a%
Reactor 25.25a.

GTO27, 27a, diode 28.28a.

Capacitor 29.29a% Diode 30° 30a, G
It consists of the TO element 27, 27a and the overcurrent protection reactor 31, and is specifically constructed as follows.

That is, the capacitor 29a is connected to the anode of the first self-extinguishing element, for example, the GTO 27a, and the capacitor 29a is
The other end is connected to the anode of the diode 30a, and the cathode of the diode 30a is connected to the cathode of the GT027g. The cathode of a switching element, such as a thyristor 26a, is connected to the connection point between the anode of the capacitor 29a and the diode 30a, and the anode of the thyristor 26a is connected to the reactor 25a.
The other end of the reactor 25a is connected to the intermediate potential of the rectifier 22 or capacitor 24a connected in series, and the anode of the first GT027a is connected to the positive electrode of the rectifier 22 or capacitor 24a. The first circuit is connected through 31 to form a closed circuit. and a second self-extinguishing element such as GTO2.
The anode of the diode 30 is connected to the anode of the capacitor 7, and the cathode of the diode 30 is connected to the capacitor 29.
9 is connected to the cathode of the GTO 27. Connecting the anode of another switching element such as a thyristor 26 to the connection point between the cathode of the diode 30 and the capacitor 29, and connecting another reactor 25 to the cathode of the thyristor 26;
The other end of the reactor 25 is connected to the rectifier 2 connected in series.
2 or the intermediate potential of capacitors 24 and 24a.

A second circuit is provided in which the cathode of the GTO 27 is connected to the negative electrode of the rectifier 22 or the capacitor 24 to form a closed circuit. Further, the first circuit and the second circuit are connected in series by connecting the cathode of the first GT027a and the anode of the second GTO27, and a diode 28a is connected in antiparallel to the GTO27a.
, and another diode 28 is connected in antiparallel to the second GTO 27 to form a set of circuits. At least one other set of circuits having the same configuration as the one set of circuits but excluding the reactor connected to the anode of the first self-extinguishing element of the first circuit. be.

In FIG. 7, the inductance of the reactor 25 is
It is selected to be equal to the sum of the inductances of the reactors 25a and 31, and the resonance time constants are made equal.

The operation shown in FIG. 7 will be explained with reference to the time chart shown in FIG. The operating mode is the same as in FIG.

Figure 8 (a) shows the gate signal of 07027g, (b) shows the gate signal of G
Gate signal of TO27, (C) is gate signal of thyristor 26a, (d) is gate signal of thyristor 26, (e
) is the voltage of the capacitor 29a, and (f) is the voltage of the capacitor 9. The energy of the capacitor 29a is transferred to the capacitor 24a in synchronization with the reactor 25a and the GTO 27a.
It is regenerated via the thyristor 26a which is energized at time t1. Similarly, the energy of capacitor 29 is
4 Heliacudle 25. It is regenerated via the thyristor 26 which is energized in synchronization with the GTO 27. The same applies to other inverter arms, so the explanation will be omitted. Since the regeneration circuit is constructed so that the voltage of each capacitor 29.29a is completely discharged by a resonance phenomenon with respect to a voltage source that is 1/2 of the DC voltage, the GTO 27, which constitutes the inverter, The snubber energy of 27a is completely regenerated to the power supply, making it possible to significantly reduce snubber loss.

Secondly, in recent years there has been a trend toward larger capacity and higher pressure inverters, etc.
A fourth embodiment to which the present invention is applied is shown in FIG.

What is different from Fig. 7 is the GTO 27a and diode 28a,
The GTO27 and diode 28 parts are described below.
It is composed of stacks 32a and 32. The GTO stack 32a includes GTOs 33a and 33b connected in series.
, 33c and snubber diodes 34a, 34b, 34
c and resistor 35a.

35b, 35c and a snubber capacitor 36a.

36b, 36a% diode 38a, 38b.

38c.

According to the circuit shown in FIG. 9, the snubber circuits provided in the individual GTOs 33a to 33c are for balancing voltage sharing during turn-off, etc.
Select by reducing the capacitance of c and the snubber loss,
-Block snubber capacitors 29a, 29, diode 30a
, 30 are designed to have a large capacity, the energy of the negative snubber circuit can be recovered to the power supply, and the conventional snubber loss can be significantly reduced.

The embodiments of the present invention described above can also be modified as follows. That is, in FIG. 7, the rectifier 22 or capacitor 24 connected in series with the anode of GT027a
The reactor 31 between the positive electrodes of a is omitted, and the second
The cathode of the GTO 27 and the negative electrode of the rectifier 22 or capacitor 24 connected in series may be connected by a reactor 31 or another reactor.

Further, in FIG. 1 or 4, the GTOI may be replaced with a GTO stack in which at least two GTOIs are connected in series.

Furthermore, in FIG. 7, the first and second GT027a
, 27 may be replaced with at least two or more GTO stacks connected in series.

[Effect of the invention] As described above, in the conventional snubber circuit, the snubber loss is
According to the present invention, the energy that was lost can be regenerated into the power supply, and a snubber loss reduction circuit that is effective in reducing loss can be provided.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram showing a first embodiment of the present invention, FIGS. 2 and 3 are time charts for explaining the operation of FIG. 1, and FIG. 4 is a circuit diagram showing a second embodiment of the present invention. 5 and 6 are diagrams for explaining the operation of FIG. 4,
FIG. 7 is a circuit diagram showing a third embodiment of the present invention, FIG. 8 is a time chart for explaining the operation of FIG. 7, and FIG. 9 is a circuit diagram showing a fourth embodiment of the present invention. , FIG. 10 is a circuit diagram showing an example of a conventional boost chopper circuit, and FIG. 11 is a time chart for explaining the operation of FIG. 10. 11... DC power supply, 12... DC reactor, 14
...Diode, 1, 27, 27 a-G
T 0, 2. 2a, 26, 26a...thyristor, 3, 3a. 15a, 15, 24.24a, 29, 29a... Capacitor, 4, 4a, 6.6a, 28, 28a. 30.30a...diode, 5*5aT
25 +25a, 31.23...Reactor, 1
6... Inverter, 22-... Rectifier, 32, 3
2 a-G T O stack. Applicant's Representative Patent Attorney Takehiko Suzue Figure 3 @ Figure 2 Figure 5 Mode (1) Figure Figure Figure Figure Figure Figure

Claims (3)

[Claims] (1) A first switching element whose anode is connected to the anode of the self-arc-extinguishing element, a capacitor in which the first switching element and one end of the switching element are connected in series, and the other end of the capacitor connected to the self-switching element. a diode connected to the cathode of the arc-extinguishing element and having its anode connected to the connection point between the first switching element and the capacitor; the cathode of this diode is connected to a reactor; the other end of the reactor is connected to the self-containing element; Two sets of snubber circuits are provided in parallel, connected to the anode of the arc-extinguishing element, and configured by connecting the anode to both ends of the capacitor in parallel with one end connected to the cathode of the self-arc-extinguishing element, A snubber loss reduction circuit characterized in that the plurality of switching elements are alternately energized to operate the circuit. (2) A first diode whose anode is connected to the anode of the self-arc-extinguishing element, this first diode and a first capacitor are connected in series, and the anode is connected to the connection point. a first switching element, and one end of the first switching element and the first reactor are connected in series,
The other end of the first reactor is connected to a first circuit connected to a DC power source or an intermediate potential of series-connected capacitors, and a second capacitor is connected to the anode of the self-extinguishing element. The other end of the capacitor is connected to the anode of the second diode, the cathode of the second diode is connected to the cathode of the self-extinguishing element, and the connection point between the second diode and the second capacitor A second switching element whose cathode is connected to the second switching element, a second reactor connected in series with the second switching element, and the other end of the second reactor connected to a DC power source or a capacitor connected in series. and a second circuit connected to an intermediate potential of the snubber loss reduction circuit, the circuit is operated by alternately energizing the switching elements of the first circuit and the second circuit. (3) Connect one end of the first capacitor to the anode of the first self-extinguishing element, connect the other end of the first capacitor to the anode of the first diode, and connect the first end of the first capacitor to the anode of the first diode. A cathode is connected to the cathode of the first self-extinguishing element, and a cathode of the first switching element is connected to a connection point between the first capacitor and the anode of the first diode, and the first switching element The anode of the element is connected to one end of a first reactor, the other end of the first reactor is connected to an intermediate potential of a DC power supply or a capacitor connected in series, and the anode of the first self-extinguishing element is , a first circuit connected to the positive electrode of the DC power supply or the capacitor to form a closed circuit,
Further, the anode of the second diode is connected to the anode of the second self-extinguishing element, the cathode of the second diode is connected to one end of the second capacitor, and the other end of the second capacitor is connected to the self-extinguishing element. connected to the cathode of the arc-extinguishing element, further connected to the connection point between the cathode of the second diode and the second capacitor, the anode of a second switching element, and connected to the cathode of the second switching element; 2 reactor is connected, the other end of the second reactor is connected to the intermediate potential of the DC power supply or capacitor connected in series, and the cathode of the self-extinguishing element is connected to the negative pole of the DC power supply or capacitor. and a second circuit forming a closed circuit, the first circuit and the second circuit connecting the cathode of the first self-arc-extinguishing element and the anode of the second self-arc-extinguishing element. death,
A set of circuits includes a third diode connected in series and connected in antiparallel to the first self-extinguishing element, and a fourth diode connected antiparallel to the second self-extinguishing element. , Part 1
There is at least one circuit having the same configuration as the circuit of the first circuit, and the anode of the first self-extinguishing element of the first circuit and the positive electrode of the DC power supply or capacitor or the second self-extinguishing element of the second circuit are connected to each other. A snubber loss reduction circuit in which a third reactor is connected to the cathode of the arc-shaped element and either the DC power supply or the negative electrode of the capacitor.