JPH06276723A - Power conversion device - Google Patents

Abstract

PURPOSE:To increase regeneration and to reduce the size of a snubber, compared with the conventional circuit. CONSTITUTION:The title power conversion device concerns to a power converter having constitution that the series circuit of self-arc-extinguishing semiconductor switching devices 11 and 12 is connected with a power source 1, and has a capacitive element 31 which can be charged to power voltage or higher by the snubber action of either of the self-arc-extinguishing switching devices 11 and 12, and a circuit which regenerates its charged electric charge to the power source 1, and a filter capacitor is connected to this capacitive element. Consequently, it becomes possible to constitute a power converter capable of reducing the snubber loss with nearly the whole capacity needed. And it become possible to make circuit configulation with less than one tenth of the capacity compared with a conventional one, and reduce th size of the power conversion device.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power converter, and more particularly to improvement of a snubber circuit.

[0002]

2. Description of the Related Art As a circuit of a power converter capable of regenerating snubber energy accompanying switching of a switching element to a power source, a circuit described in Japanese Patent Laid-Open No. 64-89972 has been proposed. This circuit regenerates snubber energy by an asymmetrical circuit in which snubber capacitors involved in switching the upper and lower semiconductor switching elements are different from each other.

Further, an asymmetric circuit in a serial multiple inverter is described in Japanese Patent Laid-Open No. 1-198280.

[0004]

In the prior art, the capacitive element is charged above the power supply voltage only by the snubber action of one of the switching elements during the switching operation, and the accumulated charge is regenerated to the power supply.

On the other hand, the conventional technique has a problem that the entire apparatus becomes large because of the asymmetrical structure.

Also, IEE transaction on industry application volume 24 number 1 manual / feblerry 198
8 (IEEE TRANSACTIONS ON INDUSTRY APPLICATIONS, VO
L.24, NO.1, JANUARY / FEBRUARY 1988) Article GIO Driving and Protection
Technique with status monitoring (GTO
Driving and Protection Technique with Status Monit
oring) Page 119 Fig11. Describes a symmetrical snubber circuit.

However, even this prior art does not consider downsizing. Also, no consideration is given to the induction failure caused by switching.

An object of the present invention is to provide a power converter capable of reducing snubber loss by further increasing the regeneration amount.

[0009]

In order to achieve the above object, the present invention relates to a power converter having a self-arc-extinguishing semiconductor switching element connected in series, wherein the self-extinguishing semiconductor switching element connected in series is provided. A plurality of capacitive elements connected in a star shape between both ends of the series body and three points thereof, a connection point of the plurality of capacitive elements, and a connection point of a voltage dividing capacitor connected in parallel to the power supply. Connect to each other.

[0010]

[Operation] When the self-extinguishing type semiconductor switching element changes from the ON state to the OFF state, a current flows into the capacitive element connected to this switching element due to the snubber action,
Charge the capacitive characteristic element. At this time, the capacitive element is charged to a voltage higher than the power supply voltage, and the difference between the stored charge and the power supply voltage is regenerated to the power supply.

The regenerative operation of the snubber energy is performed by the snubber action of any self-arc-extinguishing type semiconductor switching element connected in series.

By connecting the midpoint of this capacitive element to the midpoint of the voltage dividing capacitor, the midpoint of the self-extinguishing type switching element is connected to the power source via the capacitive element, so that The wave component is absorbed by the power supply. For this reason,
Induction obstacles are prevented along with miniaturization and power consumption.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In describing the embodiments of the present invention, the operation of the conventional example will be described first in order to clarify the features of the present invention.

The circuit shown in FIG. 16 shows an asymmetrical circuit capable of regenerating the snubber energy.

The switching element 11 is in the ON state,
When a current is applied to the load from the DC power supply 1 through the inductor 3 and the switching element 11, the snubber capacitor 31 passes through the DC power supply 1, the inductance (wiring inductance) 3, the snubber diodes 21, 22. Is charged to the power supply voltage, and snubber capacitor 3
In No. 2, when the switching element 11 is turned on, power is discharged through the path of the snubber diode 22-snubber resistor 41-switching element 11 and the voltage between contacts is reduced to zero. The current flowing through the switching element 11 that turns off the switching element 11 in this state flows into the snubber diode 21 and the snubber capacitor 32, and gradually raises the voltage of the snubber capacitor 32, but it is only charged to the power supply voltage. , Regenerative operation is not performed.

On the contrary, when the switching element 12 is in the ON state and the current flows from the load to supply the switching element 12 with the current, the snubber capacitor 31 operates in the same manner as in the ON state of the switching element 11 in the DC state. Power supply 1,
It is charged to the power supply voltage via the inductance 3, the snubber diodes 21 and 22, and the snubber capacitor 32 is also charged via the DC power supply 1, the inductance 3, the snubber diode 21, the snubber capacitor 32, and the switching element 12. Charged to the power supply voltage. When the switching element 12 is turned off in this state, the current flowing through the switching element 12 flows into the snubber capacitor 32, the snubber diode 22 and the snubber capacitor 31. The voltage of the snubber capacitor 32 is gradually lowered, and at the same time, the snubber capacitor 31 is charged to the power source voltage or higher. The charged electric charge is regenerated in the path of the snubber capacitor 31, the snubber resistor 41, the inductance 3 and the DC power supply 1.

As described above, in the conventional circuit, the regenerative operation can be performed only by the snubber action of one switching element.

Further, a snubber capacitor 32 is connected in parallel to the switching element 11, and the switching element 12
Is an asymmetrical circuit in which a series connection of the snubber capacitor 31 and the snubber capacitor 32 is connected in parallel. Therefore, for example, the snubber capacitor capacity required from the power cutoff performance of the switching elements 11, 12 is 2 μF or more, and the snubber capacitor is If the capacitance of the capacitor 31 is C ₁ and the capacitance of 32 is C ₂ , the relationship between these capacitors is as shown in FIG.

As described above, when C ₂ is ₂ μF, C ₁ requires an infinite capacity, which is unsuitable as a combination of snubber capacitors.

When the capacitance of C ₁ C ₂ is selected as the minimum capacitance of the capacitor, C ₁ = C ₂ = 4 μF.

At this time, the parallel capacitance of the switching element 11 is C ₂ = 4 μF, and the parallel capacitance of the switching element 12 is
C ₁ C ₂ / (C ₁ + C ₂ ) = ₂ μF.

Thus, when the capacitance of the entire capacitor is determined to be the minimum and the capacitance of the capacitor is determined, the capacitance of the upper and lower switching elements as a snubber circuit is different, and the circuit operation is different between the upper and lower switching elements and the The snubber circuit capacitance becomes 4 μF with respect to the required capacitance of 2 μF, which increases the loss of the snubber resistor 41.

[0023] Practically, determines the capacitance as C ₁ »C _2, for example, C ₂ = 2.1μF, so that the connecting order of C ₁ = 42μF.

Such a circuit according to the prior art has a drawback that a practical circuit cannot be constructed unless a capacitor having a required capacity or more is used. Therefore, for example, in a power converter mounted on a train or the like having a limited size, there is a problem in that a conventional circuit using a capacitor having a required capacity or more cannot be mounted under the floor of the train.

An embodiment of the present invention which solves the problems of the conventional circuit will be described with reference to the drawings.

FIG. 1 shows an embodiment of the present invention.
The circuit of the power converter which comprised the single phase bridge inverter by the semiconductor switching element is shown.

A self-extinguishing type semiconductor switching device, for example, GTO, transistor, IGBT (hereinafter simply referred to as switching device) 11 and 12 is connected in series, and the connection point of these switching devices is a load as an inverter output terminal. 9 is connected. This switching element 1
A series body of the snubber diode 21, the snubber capacitor 31, and the snubber diode 22 is connected in parallel with the series body of 1, 12, and the connection point of the switching elements 11 and 12, the cathode of the snubber diode 21, and the snubber diode 22.
Snubber capacitors 32 and 33 are respectively connected between the anodes of the. Snubber resistors 41 and 42 are connected in parallel to the snubber diodes 21 and 22, respectively. Further, freewheel diodes 15 and 16 are connected in antiparallel to the switching elements 11 and 12, respectively.

Next, the function of this circuit will be described.

The switching element 11 is in the ON state,
DC power supply 1 to inductance 3, switching element 1
A current indicated by a solid arrow in FIG. At this time, the snubber capacitor 31 is
DC power supply 1, inductance 3, snubber diode 2
1, the snubber capacitor 31 and the snubber diode 22 are charged up to the power supply voltage, and the snubber capacitor 3
In No. 2, when the switching element 11 is turned on, the electric charge is discharged through the path of the snubber resistor 41-switching element 11, and the voltage between contacts is reduced to zero.

The snubber capacitor 33 is charged to the power supply voltage via the DC power supply 1, the inductance 3, the switching element 11, the snubber capacitor 33, and the snubber diode 22. Switching element 1 in this state
When 1 is turned off, the current flowing through the switching element 11 passes through the snubber diode 21 and flows into the snubber capacitor 32 and the parallel capacitors of the snubber capacitors 31 and 33, as shown by the dashed arrow in FIG. While gradually increasing the voltage of the snubber capacitor 32 and decreasing the voltage of the snubber capacitor 33, the switching element 1
The potential at the connection point of 1 and 12 is lowered. At this time, the capacitor 33 releases the accumulated electric charge and charges the capacitor 31 to the power supply voltage or more. After that, when the potential at the load output point drops to almost the same level as the negative terminal of the DC power supply 1, the diode 16 turns on and the current continues to freewheel to the load 9. At this time, the switching element 1
1 includes a snubber capacitor 32 and a snubber capacitor 31.
33 and the series circuit of 33 are connected in parallel, and the capacitance is connected. On the contrary, as shown in FIG. 1B, the switching element 12 is in the ON state, current flows out from the load as indicated by the solid line arrow in the figure, and the switching element 12 is energized. . At this time, the snubber capacitor 31 has the DC power supply 1, the inductance 3, the snubber diode 21,
It is charged to the power supply voltage via the snubber capacitor 31 and the snubber diode 22. Snubber capacitor 32
Is similarly charged to the power supply voltage via the DC power supply 1, the inductance 3, the snubber diode 21, the snubber capacitor 32, and the switching element 12, and the snubber capacitor 33 turns on the switching element 12 and the snubber resistor 42. Is discharged to zero via. When the switching element 12 is turned off in this state, the current flowing through the switching element 12 flows in parallel to the snubber capacitor 33 and the series circuit of the snubber capacitors 32 and 31 as indicated by the broken line arrow in FIG. After passing through 22, the voltage of the snubber capacitor 33 is gradually increased, the voltage of the snubber capacitor 32 is decreased, and the potential of the connection point between the switching elements 11 and 12 is increased. At this time, the capacitor 32 releases the accumulated charge and charges the capacitor 31 to the power supply voltage or more. After that, when the potential at the load output point rises to almost the same level as the plus terminal of the DC power supply 1, the diode 15 turns on, and the free current with the current from the load 9 continues. At this time, the switching element 12 is connected to the capacitance in which the series circuit of the snubber capacitor 33 and the snubber capacitors 32 and 31 are connected in parallel.

By the above operation, the switching element 11,
12 alternately repeats switching.

FIG. 2 shows the principle of reducing snubber loss. The induction motor, which is the load 9, is driven by the three-phase inverter.

Now, consider a state in which the switching elements 11 and 12 "are turned on. At this time, the capacitor 33
The electric charges are accumulated in the direction shown in the figure by the snubber action when the switching element 12 is turned off.

Although the snubber circuit is shown only for the U phase,
Of course, it also exists in the V phase and W phase.

When the switching element 11 is turned off in this state, the above-mentioned current flows. Here, a part will be described.

The energy stored in the inductance 3 is released as a current.

Inductance 3, snubber diode 2
1, the snubber capacitor 31, the snubber capacitor 33, the load 9, the W-phase switching element 12 ″, and the power source 1 are returned to the inductance 3.

This current pushes up the voltage of the snubber capacitor 31 to the power source voltage or more and gives the load 9 the electric charge of the snubber capacitor 33 charged by the snubber action. Then, the snubber capacitor 33 is discharged until there is no charge.

Further, when the current supplied by the inductance 3 is exhausted, the snubber capacitor 31 rises above the power supply voltage and regenerates the charge for the voltage to the power supply 1 via the snubber resistors 41 and 42.

By these actions, the snava loss is effectively reduced.

In addition, the above-mentioned prior art IEEE, V
ol. 24, No1, JANUARY / FEBRUARY 1988, 11
In the circuit described in FIG. 9 on page 9, a diode is connected between the snubber capacitors 31, 32 and 33 connected in the delta type in FIG. This cannot be miniaturized for the reasons described below. In particular, when this device is placed under the floor of an electric railway vehicle, there are problems that it is difficult to install and the layout is not flexible due to the relationship with other underfloor equipment.

In this embodiment, since nothing is connected between the snubber capacitors 31, 32, 33 connected in the delta type, the inductance due to the connection can be reduced.

However, in the prior art, since the diode is inserted, not only the wiring length between the capacitors increases but also the forward voltage of the diode is generated. These increase the spike voltage generated at the time of turning off, which is peculiar to the self-extinguishing element. To absorb this voltage, the capacity of the snubber capacitor must be increased.

In addition, the number of parts can be increased by inserting the diode in the delta type circuit.

Therefore, in this prior art, no consideration is given to miniaturization.

By the way, in FIG. 1, a snubber diode 21, a snubber capacitor 31, and a snubber diode 22 which are connected in parallel with the series body of these switching elements.
The series circuit of has a clamp function.

That is, the electromagnetic energy stored in the inductance 3 (including the stray inductance existing in the circuit between the clamp circuit and the power supply) is absorbed. For this reason,
This electromagnetic energy generated at the time of switching is not applied to the switching elements 11 and 12, and the withstand voltage design of these switching elements can be lowered.

The capacitance C of the snubber capacitor 31 shown in FIG.
_1, when the C ₂ to equal the capacitance of the snubber capacitor 31, the parallel snubber capacitor capacitance of the switching element _{11, C 2 + C 1 C 2} / (C 1 + C 2), the parallel snubber capacitor capacitance of the switching element 12 is C ₂ + C ₁ C ₂
/ (C ₁ + C ₂ ), which is equal.

Here, by substituting specific numerical values, the capacitance of the snubber circuit of the present invention will be examined.

If the snubber capacitor capacitance of the switching elements 11 and 12 is set to 2 μF or more as in the case of the conventional example, the relationship between C ₁ and C ₂ becomes as shown in FIG.

Further, unlike the conventional snubber circuit, C ₁ and C ₂
The snubber capacitor capacities for the switching elements 11 and 12 are equal in any combination of the values of.

The total snubber capacitor capacity becomes minimum when C ₁ = C ₂ , and C ₁ = C ₂ = 4/3 μF. In this case, the total snubber capacitor capacity is calculated to be 4 μF, and the capacitor capacity is 1 / F compared to the above-mentioned conventional example.
It turns out that it will be 20 or less. As described above, according to the present embodiment, the total snubber capacitor capacity of the snubber circuit can be significantly reduced as compared with the conventional snubber circuit, and the size can be naturally reduced. According to this condition,
Since the capacities of the upper arm and the lower arm that contribute to the snubber action are equal, the value of C ₁ should be set in consideration of the clamp function, etc.
It does not matter if C ₁ > C ₂ .

The electric charge of the capacitor 31 charged to the power source voltage or more when the switching elements 11 and 12 are turned off is regenerated to the power source 1 via the snubber resistor 42, the snubber capacitor 31, and the snubber resistor 41.

In the present embodiment, a resistor is used as a discharging means for energy regeneration, but it is not particularly limited as long as it can discharge the electric charge stored in the capacitor. Even if the circuit is configured by using it, the electric charge accumulated by the snubber action can be regenerated to the power supply.

However, in the circuit actually used, resonance occurs due to the snubber capacitor and the inductance in the circuit, and there is no power supply capable of absorbing this resonance at present, so a resistor is used as the discharging means. Since the resistor serving as the discharging means is connected in the circuit for the purpose of absorbing the above-mentioned resonance, in the circuit in FIG. 1, the optimum resistance value is determined from the values of the capacitor 31 and the inductance 3.

Further, in the other embodiments described later, similarly, a resistor is used as the discharging means. FIG. 9 shows an example in which the circuit shown in FIG. 1 is mounted.

As a snubber circuit of the switching element 11, a snubber diode 21, a snubber capacitor 22, a snubber capacitor 31, and a snubber capacitor 33 are connected in parallel.

As a snubber circuit of the switching element 12, a snubber capacitor 33, a snubber diode 22, a snubber capacitor 32, and a snubber capacitor 31 are connected in parallel.

In this way, the circuits can be arranged to the same extent for the switching elements 11 and 12 having the wiring inductance. In addition, the snubber diode 2 is provided by directly connecting (directly attaching) the switching element and the diode.
1, the snubber capacitor 32, the switching element 11 and the snubber capacitor 33, the snubber diode 22-the switching element 12 can be minimized the loop of the snubber circuit, it is possible to easily reduce the inductance of the wiring.

FIGS. 3 and 4 show second and third embodiments of the power converter which constitutes a single-phase bridge inverter.

FIG. 3A shows the delta and star conversions, paying attention to the fact that the snubber capacitors 31, 32 and 33 in FIG. 1 are constructed in the delta type.

In this case, since two capacitors are formed in series, there is an advantage that the withstand voltage of the capacitors can be reduced, and the withstand voltage of the capacitors is 1 compared with the circuit of FIG.
It can be / 2.

In FIG. 3B, the potential at the connection point between the capacitors 37 and 38 is stabilized at a voltage half the voltage of the power supply 1. Voltage dividing capacitor 7 in parallel with power supply 1
7, 78 were connected, and the midpoint and the connection points of the capacitors 37, 38 were connected. This allows stabilization to be achieved.

By connecting the midpoints of the capacitors 37 and 38 to the midpoints of the filter capacitors 77 and 78, the midpoints of the switching elements 11 and 12, which are the output points to the load of the power converter, are connected to the snubber capacitors. Since it is connected to the power supply via 39, the harmonic component at the output point can be absorbed by the power supply.

Now, the inductance 9 is interposed between the midpoints of the capacitors 37 and 38 and the midpoints of the filter capacitors 77 and 78.

When the capacitance of the snubber capacitor 39 is C and the inductance 9 is L, the LC resonance frequency is f = 1 / (2
It becomes a π route (LC), and the filter action in the vicinity of this frequency acts and is absorbed by the power supply, so that the harmonic current of the load does not flow.

As described above, since the harmonic current to the load is not passed, the influence of the harmonic current on the radio or induction radio can be reduced.

Further, FIG. 4 shows an embodiment in which a plurality of delta type capacitor circuits are formed in series. The capacitor circuit is complicated, but it can serve the purpose as well.

Incidentally, as in the case of FIG. 3B, the capacitor 31
.. can be stabilized by connecting the respective connection points of a, 31b ... With the connection points of the same number of voltage dividing capacitors.

In FIG. 4 (b) as well, the harmonic component contained in the output point to the load can be similarly absorbed by the power supply.

FIG. 5 shows an example of a power converter in which the circuit of the embodiment shown in FIG. 1 is configured in three phases.

From the DC power supply 1, the inductances 3, 5,
Power is supplied via 7 and switching elements 11, 12 and 51, 52, 81, 82 are respectively connected in series.
In the phase inverter, each snubber diode 2
1-Snubber capacitor 31-Snubber diode 22 series circuit, snubber diode 61-Snubber capacitor 71
-Series circuit of snubber diode 62, snubber diode 91-snubber capacitor 101-snubber diode 92
Of the snubber capacitors 31, 71,
Snubber capacitors 32, 33, 72, 73, 102 and 103 are connected between both ends of 101 and the output points of the respective phases.

Here, the snubber capacitors 31, 71, 1
Since 01 is always charged to the power supply voltage, it can be connected in parallel. As a result, the snubber resistors are integrated, and the snubber resistors 41 and 42 are connected between the positive terminals of the snubber capacitors 31, 71, 101 and the positive terminal of the DC power source, and between the negative terminals of the snubber capacitors 31, 71, 101 and the DC power source. Connected between the negative terminals respectively. Here, the mutual inductance of the snubber capacitors 31, 71, 101 can be reduced, so that the three phases can be collectively collected.

FIG. 6 shows a circuit of a power converter in which a semiconductor switching element constitutes a serial multiple inverter.

The positive and negative terminals and the neutral terminal are output from the DC power supplies 1 and 2, and the switching elements 11 to 14 are connected in series between them, and
The connection points of the switching elements 11 and 12 and the connection points of the switching elements 13 and 14 are connected to neutral terminals via clamp diodes 19 and 20, respectively.

This circuit is similar to the circuit of the embodiment shown in FIG.
They are connected between the switching element 11 and the Glump diode 19, and between the clamp diode 20 and the switching element 14, respectively. That is, the snubber diode 2 is connected to the switching element 11 and the dullamp diode 19.
1, a series circuit of the snubber capacitor 31 and the snubber diode 22 are connected in parallel, and the snubber capacitors 32 and 33 are connected between both ends of the snubber capacitor 31 and the connection point of the switching element 11 and the lamp diode 19. A similar snubber circuit is vertically symmetrically connected between the glump diode 20 and the switching element 14. In the serial multiple inverter circuit, the switching element 11 and the lump lamp diode 19, and the lump lamp diode 20 and the switching element 14 are switched alternately, so that the embodiment shown in FIG. 1 can be applied. FIG. 10 is an example of the operation mode of the embodiment shown in FIG. 5, and shows the relationship between the operation of the switching elements 11, 12, 13 and 14 and the output voltage. The voltages of the DC power supplies 1 and 2 in the figure are both E.

First, both the switching elements 12 and 13 are turned on and the switching elements 11 and 14 are turned off, so that the neutral potential E is selected as the output voltage.

Next, in order to select the output voltage 2E, the switching elements 11 and 12 are turned on and the switching elements 13 and 14 are turned off. Here, in order to prevent the short circuit of the DC current 1, 13 is turned off and then 11 is turned on.

Next, the output voltage E is selected again by turning off 11 and the switching elements 11 and 12 are both turned off, and zero is selected as the output voltage by turning on 13 and 14.

Thus, in the serial multiple inverter, zero,
The output voltage can be changed in the order of E, 2E, E, and zero.

Here, each output voltage changes A, B,
The operation of the circuit shown in FIG. 5 in the C and D modes will be described.

FIG. 12 shows a mode in which the output voltage changes from E to 2E.

When the switching elements 12 and 13 are turned on, a current is supplied to the load from the neutral point of the DC power sources 1 and 2 through the clamp diode 19 and the switching element 12 as shown in the figure.

At this time, the snubber capacitors 31, 32, 3
Since the switching element 11 is turned off, the potential of 3 is charged to the power supply voltage E by the switching element 11, and the snubber capacitor 31 becomes by the inductance 3-snubber diode 21-snubber capacitor 31-snubber diode 22.
The power supply voltage E is charged. Since the snubber capacitor 33 is connected to the neutral side on both the negative sides of the snubber capacitors 31 and 33, its electric charge is discharged.

From this state, the operation of the snubber circuit in the mode in which the switching element 11 is turned on and the output voltage becomes 2E is as follows.

When the switching element 11 is turned on, the current flowing in the clamp diode 19 is canceled by the current flowing through the DC power supply 1-inductance 3-switching element 11-clamp diode 19, and then the clamp diode 19 is The voltage blocking capability is restored and the snubber capacitor 33 is charged as shown.

On the other hand, the electric charge of the snubber capacitor 32 is the snubber resistor 41-inductance 3-switching element 1
While being discharged to zero through 1, a part of the electric charge is also discharged in the path of the snubber capacitor 32- snubber capacitor 31-snubber diode 22-clamp diode 19-snubber capacitor 32, and once the snubber capacitor 3
Transfer that energy to 1.

A part of the energy of the snubber capacitor 32 transferred to the snubber capacitor 31 is regenerated to the DC power source 1 by the closed circuit of the snubber capacitor 31-snubber resistor 41-DC power source 1-snubber diode 23-snubber resistor 44. To be done.

After that, the switching element 13 is turned off, and current is supplied to the DC power source 1-inductance 3-switching element 11-switching element 12-load.

FIG. 13 shows a mode in which the output voltage changes from 2E to E.

Since the switching elements 11 and 12 are turned on, the main current is supplied to the DC power source 1-inductance 3-switching element 11-switching element 12-load as shown in the figure.

At this time, the snubber capacitors 31, 32, 3
With respect to the potential of 3, the snubber capacitor 32 is discharged to zero when the switching element 11 is turned on, and the snubber capacitor 31 is charged to the power supply voltage E as described above. The snubber capacitor 33 is a clamp diode 19
Is turned off, the power source voltage E is charged.

When the switching element 11 is turned off from this state, the current that has been flowing so far flows into the snubber diode 21-snubber capacitor 32 and simultaneously flows into the snubber capacitor 31-snubber capacitor 33.
The electric charge stored in the snubber capacitor 33 is bypassed to the load and discharged to zero.

After that, a current is supplied to the load through the clamp diode 19 and the switching element 12.

On the other hand, the electric charge accumulated in the snubber capacitor 33 is discharged by bypassing to the load, and at the same time,
The snubber capacitor 31 is charged to the power source voltage E or higher. After that, the power is regenerated to the power source 1 by the regenerative closed circuit similar to the above.

FIG. 14 shows a mode in which the output voltage changes from E to zero.

Since the switching elements 12 and 13 are turned on, from the same state as when E of FIG. 11 is selected,
The operation of the snubber circuit in the mode in which the output voltage changes from E to zero when the switching element 12 is turned off is as follows.

When the switching element 12 is turned off, the current that has been flowing so far is bypassed to the snubber diode 23-snubber capacitor 36-freewheel diode 17, and at the same time shunted to the snubber capacitor 34-snubber capacitor 35.

The electric charge of the snubber capacitor 35, which has been charged to the power supply voltage E because the switching element 14 is off, is bypassed to the load and discharged to zero.

After that, the free wheel diode 18-
Through the freewheel diode 17, the load current freewheels.

On the other hand, the electric charge stored in the snubber capacitor 35 is discharged by bypassing the load, and at the same time, the snubber capacitor 34 is charged to the power source voltage E or higher (during the snubber operation), and then the snubber capacitor 34 is discharged. The electric charge stored in the power source 2 is regenerated in the power source 2 by the closed circuit of the snubber capacitor 34-the snubber resistor 44-the snubber diode 22-the power source 2 and the snubber resistor 43.

FIG. 16 shows a mode in which the output voltage changes from zero to E.

Since the switching elements 13 and 14 are turned on, current flows from the load through the path shown in the figure.

At this time, the snubber capacitors 34, 35, 3
Regarding the potential of 6, the battery 35 is discharged to the cell, the battery 34 is charged to the power supply voltage E by the snubber diode 23, the snubber capacitor 34, the snubber diode 24, and the inductance 4, and the snubber capacitor 36 is connected to the clamp diode 20.
Is off, so the power source voltage E is charged.

The operation of the snubber circuit in the mode of turning on the switching element 12 after turning off the switching element 14 in this state is as follows.

When the switching element 14 is turned off, the main circuit current that has been flowing so far is shunted to the parallel circuit of the series body of the snubber capacitors 36 and 34 and the snubber capacitor 35, and flows to the DC power source 2 via the snubber diode 24. .

At this time, the electric charge of the snubber capacitor 36 moves to the snubber capacitor 34, and the electric charge becomes zero. Also,
The snubber capacitor 34 is also charged to the power supply voltage E.

After that, the switching element 12 is turned on,
The main circuit current flows to the power supply 1 through the path of the switching element 13 and the clamp diode 20.

The electric charge stored in the snubber capacitor 34 at the power supply voltage or higher is regenerated to the power supply voltage 2 by the open circuit of the snubber resistor 44-snubber diode 22-power supply 2-snubber resistor 43-snubber capacitor 34. .

As described above, according to the present embodiment, it is possible to obtain the same effect as in the case of the power converter having the single-phase bridge inverter. When the snubber capacitor capacity is minimized, the snubber capacitors 31, 32, 33,
It is clear from the previous embodiment that the capacities of 34, 35 and 36 may be the same.

FIG. 7 shows an example of a power converter in which the circuit of the embodiment shown in FIG. 6 is configured in three phases. As shown in FIG. 5, snubber capacitors 31, 71, 101 and snubber capacitors 34, 37, 104 can be connected in parallel. At this time, the snubber resistance is the snubber capacitors 31, 7
1, 101 plus terminal and plus terminal of DC power supply, snubber capacitors 31, 71 and 101 minus terminal and snubber capacitors 34, 71 and 101 plus terminal, snubber capacitors 34, 71 and 101 minus terminal and DC power source 41, 44, 43 are connected between the negative terminals, respectively. Here, the snubber capacitors 31, 71, 1
By reducing the mutual inductance of 01 and 34, 71, 101, it is also possible to collectively combine the three phases.

The other embodiments of the present invention shown in FIGS. 3 and 4 are not limited to the application to the serial multiplexing circuit as described above,
When applied to a phase inverter, in the embodiment of FIG. 3, the series circuits of the snubber capacitors 34 and 35 can be aggregated in parallel for each phase, and the connection points of the snubber capacitors 34 and 35 can also be aggregated into three phases.

In the embodiment shown in FIG. 4, the respective terminal points of the snubber capacitors 31, 31, a, b, c ... Can be integrated into three phases.

Here, in FIG. 1, the snubber resistor 41
Although the positive terminal of is connected to the negative side of the inductance 3, it is possible to connect to the positive side of the inductance 3.

In FIG. 6, snubber resistors 41 and 43 are connected to the plus side of the inductance 3 and the minus side of the inductance 4, respectively. Is also possible.

Similarly, in the embodiments shown in FIGS. 3 and 4, the positive terminal of the snubber resistor 41 can be connected to the positive side of the inductance 3.

Further, the inductance 3 shown in the embodiment is
8 to 8 act to suppress the current at the time of switching on, but it is not necessary to provide them as specific constituent elements.
It is sufficient as the stray inductance present in the circuit.

In the embodiment of the present invention, the example of the power converter in which the inverter is composed of the switching elements has been described, but the same effect can be obtained also in the power converter in which the chopper circuit is similarly composed.

The case where this inverter is used as a control device for an electric railway vehicle has been described above, but the present invention is not limited to this, and any other vehicle such as an electric vehicle or a rolling mill that requires low loss and small size can be used. Are the subject of the present invention.

[0120]

According to the present invention, by the snubber action accompanying the switching of the switching element, the electric charge stored in the capacitive element can be regenerated to the power source by any of the snubber actions, and the snubber loss can be reduced.

Further, since the capacitive element that acts as a snubber is shared by the switching elements and the connection configuration can be the same, the power converter can be configured with a capacitive element having a required capacity and the size of the power converter can be reduced. be able to.

[Brief description of drawings]

FIG. 1 is a circuit diagram of a first embodiment of the present invention.

FIG. 2 is a circuit diagram of the first embodiment of the present invention.

FIG. 3 is a circuit diagram of a second embodiment of the present invention.

FIG. 4 is a circuit diagram of a third embodiment of the present invention.

FIG. 5 is a circuit diagram of an example in which the first embodiment has three phases.

FIG. 6 is a circuit diagram of an example in which the first embodiment is serially multiplexed.

FIG. 7 is a circuit diagram of an example in which the first embodiment is configured as a three-phase serial multiplex.

FIG. 8 is a circuit diagram of an example of snubber capacitor capacitance of the circuit shown in the related art.

FIG. 9 is a circuit diagram showing an example of snubber capacitor capacitance of the circuit according to the present invention.

FIG. 10 is a circuit diagram of an example of a mounting diagram of the present invention.

11 is a diagram showing the relationship between the operation of the switching element shown in FIG. 6 and the output voltage.

FIG. 12 is a circuit diagram showing an example of operation modes of the circuit shown in FIG.

13 is a circuit diagram showing an example of operation modes of the circuit shown in FIG.

14 is a circuit diagram showing an example of operation modes of the circuit shown in FIG.

15 is a circuit diagram showing an example of operation modes of the circuit shown in FIG.

FIG. 16 is a circuit diagram of an example of an asymmetric circuit shown in the related art.

[Explanation of symbols]

1 ... Power supply, 9 ... Load, 11, 12 ... Switching element,
15 ... Free wheel diode, 21 ... Snubber diode, 31, 32a, 32b ... Snubber capacitor, 41
… Snubber resistors, 77… Voltage dividing capacitors.

Claims (1)

[Claims] 1. A power converter comprising self-extinguishing type semiconductor switching elements connected in series, wherein a star type is provided between both ends of a series body of the self-extinguishing type semiconductor switching elements connected in series and three points thereof. A power converter characterized in that a plurality of capacitive elements connected to each other, a connection point of the plurality of capacitive elements, and a connection point of a voltage dividing capacitor connected in parallel to a power supply are connected to each other.