JPH0731158A - Snubber energy recovery circuit for power converter - Google Patents

Abstract

PURPOSE:To eliminate the need for a semiconductor switch having high breakdown voltage by connecting a voltage clamp circuit, comprising a clamp diode and a clamp capacitor, in parallel with a snubber capacitor. CONSTITUTION:This snubber energy recovering circuit is different from a conventional circuit in that a positive pole side voltage clamp circuit 31, comprising a clamp capacitor(CC) 31C and a clamp diode(CD) 31D, is connected in parallel with a snubber capacitor(SC) 8C. A third energy recovery circuit 42, comprising a third recovery diode 42D and a third recovery reactor 42L, is inserted between the CC 31C and the negative pole side of a DC power supply 2. A negative pole side voltage clamp circuit 41, comprising a CC 41C and a CD 41D, is connected in parallel with an SC 9C. A fourth energy recovery circuit 32. comprising a fourth recovery diode 32D and a fourth recovery reactor 32L, is inserted between the CC 41C and the positive pole side of the DC power supply 2. When the voltage of the SC 9C exceeds that of the CC 41C, the CD 41D is conducted and the voltage of a semiconductor switch 4 is restricted to the same level as that of the CC 41C.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a snubber energy recovery circuit of a power conversion device for recovering energy accumulated in a snubber attached to a semiconductor switch when power conversion is performed by turning the semiconductor switch on and off. .

[0002]

2. Description of the Related Art It is well known that power conversion can be performed by forming a power conversion device with a semiconductor switch and turning the semiconductor switch on and off. Hereinafter, the present invention will be described in detail by taking an inverter that converts DC power into AC power as an example of the power converter. FIG. 5 is a circuit diagram showing a first conventional example of one phase of an inverter. In FIG. 5, the positive-side semiconductor switch 4 and the negative-side semiconductor switch 6 are configured by antiparallel connection of an insulated gate bipolar transistor (abbreviated as IGBT hereinafter) as a semiconductor switching element and a feedback diode. The positive side semiconductor switch 4 and the negative side semiconductor switch 6 are connected in series and connected between the positive and negative sides of the DC power supply 2, and the positive side semiconductor switch 4 and the negative side semiconductor switch 6 are alternately turned on and off. DC power supply 2
It is possible to convert the DC power from the AC power into AC power and take it out from the AC terminal 7.

When the semiconductor waveforms 4 and 6 are turned on or off, when a current waveform overlaps with the voltage waveform (an overlap period is a period in which a current flows while a voltage is applied), a transient power loss ( So-called switching loss) occurs. Even if the amount of this switching loss per time is small, the generated loss per unit time becomes large in a power conversion device with a high switching frequency such as a pulse width modulation control inverter. This is a wasteful waste of energy, which reduces the conversion efficiency of the device,
There is an inconvenience that an extra equipment is required for processing the generated heat and the apparatus becomes large.

Therefore, in the first conventional example circuit of FIG. 5, an inductance and a capacitor are inserted to reduce the above-mentioned overlap period. That is, the positive electrode side suppression reactor 3 is inserted between the DC power source 2 and the positive electrode side semiconductor switch 4, and the negative electrode side suppression reactor 5 is inserted between the DC power source 2 and the negative electrode side semiconductor switch 6 to turn on the IGBT at turn-on. The switching loss is reduced by suppressing the increase rate of the current flowing into the. Further, a positive side snubber circuit 8 is connected in parallel to the positive side semiconductor switch 4 and a negative side snubber circuit 9 is connected in parallel to the negative side semiconductor switch 6 to mitigate the voltage rise rate when the IGBT is turned off. To reduce switching loss. That is, the positive side snubber circuit 8 is composed of the snubber capacitor 8C, the snubber diode 8D and the snubber resistor 8R, and the negative side snubber circuit 9 is also the snubber capacitor 9 similarly.
Since it is composed of C, the snubber diode 9D, and the snubber resistor 9R, the energy stored in the suppression reactor when the IGBT is turned off is absorbed by each snubber capacitor. However, the energy absorbed by the snubber capacitor is released to the snubber resistor and consumed when the IGBTs next turn on. That is, the energy absorbed by the snubber capacitor becomes heat and is wasted.

FIG. 6 is a circuit diagram showing a second conventional example for one phase of an inverter. This is a circuit diagram showing means for recovering the energy accumulated in the snubber capacitor described above in the first conventional example circuit of FIG. This is an additional circuit, which is the circuit proposed in Japanese Patent Application No. 5-874. The DC power supply 2, the positive electrode side suppression reactor 3, the positive electrode side semiconductor switch 4, the negative electrode side suppression reactor 5, the negative electrode side semiconductor switch 6, the AC terminal 7, the snubber capacitor 8C and the snubber diode 8D described in the second conventional example circuit, and The names, applications, and functions of the snubber capacitor 9C and the snubber diode 9D have already been described in the first conventional example circuit of FIG. 5, and therefore their description will be omitted.

In the second conventional circuit shown in FIG. 6, the positive-side snubber 11 is composed of a series circuit of a snubber capacitor 8C and a snubber diode 8D, and the positive-side snubber 11 is connected in parallel to the positive-side semiconductor switch 4 for auxiliary operation. The positive-side energy absorption circuit 12, which is a series connection of the capacitor 12C, the auxiliary diode 12D, and the auxiliary reactor 12L, is connected in parallel to the snubber diode 8D. Further, a first energy recovery circuit 23 including a first regenerative diode 23D and a first regenerative reactor 23L connected in series between an arbitrary connection point of the positive side energy absorption circuit 12 and the negative side.
Have been inserted. Similarly, the negative side snubber 21 which is a series connection of the snubber capacitor 9C and the snubber diode 9D is connected in parallel to the negative side semiconductor switch 6, and the snubber diode 9D includes an auxiliary capacitor 22C, an auxiliary diode 22D and an auxiliary reactor 22L connected in series. The negative electrode side energy absorption circuit 22 is connected in parallel, and the second regenerative diode 13D and the second regenerative reactor 13L are connected in series between an arbitrary connection point of the negative side energy absorption circuit 22 and the positive side. Second energy recovery circuit 13 consisting of
Have been inserted.

When the circuit is constructed as described above, the snubber capacitor 8 connected in parallel to the positive side semiconductor switch 4 is connected.
The operation of regenerating the charge accumulated in C to the power supply side will be described below. The charges accumulated in the snubber capacitor 8C are transferred through the route of the snubber capacitor 8C → the positive side semiconductor switch 4 → the auxiliary capacitor 12C → the auxiliary diode 12D → the auxiliary reactor 12L → the snubber capacitor 8C while the positive side semiconductor switch 4 is on. The auxiliary capacitor 12C is discharged. Next, when the positive side semiconductor switch 4 is turned off and the negative side semiconductor switch 6 is turned on, the charges transferred to the auxiliary capacitor 12C are stored in the auxiliary capacitor 12C.
C → Negative side semiconductor switch 6 → Negative side suppression reactor 5
→ 1st regenerative reactor 23L → 1st regenerative diode 23
Since it discharges in the path of D → auxiliary capacitor 12C,
The current of the regenerative reactor 23L increases.

Next, when the negative side semiconductor switch 6 is turned off, the current flowing through the first regenerative reactor 23L causes the first regenerative reactor 23L → the first regenerative diode 23D → the auxiliary capacitor 12C → the positive side semiconductor switch 4 → the positive side suppression. Reactor 3 → DC power supply 2 → First-generation reactor 23
It flows through the path of L to regenerate energy to the DC power supply 2, reduce the current of the first regenerative reactor 23L, and further reduce the voltage of the auxiliary capacitor 12C. By repeating the operation described above, the electric charge of the snubber capacitor 8C is regenerated to the DC power supply 2.

The charges accumulated in the snubber capacitor 9C connected in parallel to the negative side semiconductor switch 6 are stored in the snubber capacitor 9C → the negative side energy absorption circuit 22 → the negative side semiconductor while the negative side semiconductor switch 6 is on. Discharge to the auxiliary capacitor 22C through the path from the switch 6 to the snubber capacitor 9C. Next, during the period in which the negative side semiconductor switch 6 is off and the positive side semiconductor switch 4 is on, the charge transferred to the auxiliary capacitor 22C is the auxiliary capacitor 22C → the second regenerative diode 13D → the second regenerative reactor 13L. → Positive side suppression reactor 3 → Positive side semiconductor switch 4 → Auxiliary capacitor 12C is discharged along the path to increase the current of the second regenerative reactor 13L.

Next, when the positive electrode side semiconductor switch 4 is turned off, the current of the second regenerative reactor 13L changes from the second regenerative reactor 13L to the DC power source 2 to the negative electrode side suppression reactor 5 to the negative electrode side semiconductor switch 6 to the auxiliary capacitor 22C.
2nd regeneration diode 13D → 2nd regeneration reactor 13L
, And regenerates energy to the DC power supply 2.
As a result, the current of the second regenerative reactor 13L decreases,
The voltage of the auxiliary capacitor 22C is further reduced. By repeating the above operation, the electric charge of the snubber capacitor 9C is regenerated to the DC power supply 2.

[0011]

FIG. 7 is an operation circuit diagram showing a current path when the second conventional example circuit of FIG. 6 operates, which is necessary in the second conventional example circuit of FIG. Only the circuit elements are shown. In the circuit of FIG. 7, when the positive-side semiconductor switch 4 is turned on while the load current _IO is flowing back from the antiparallel diode of the negative-side semiconductor switch 6 toward the AC terminal 7, the negative-side semiconductor switch 6 is turned on. The antiparallel diode is turned off, and the load current I _O is diverted to the path from the positive side semiconductor switch 4 to the AC terminal 7. At this time, the charging current I ₉ flows to the snubber capacitor 9C through the path of the DC power supply 2 → the positive electrode side suppression reactor 3 → the positive electrode side semiconductor switch 4 → the snubber diode 9D to charge the snubber capacitor 9C. However, during this charging, the DC power supply 2, the positive electrode side suppression reactor 3, and the negative electrode side suppression reactor 5 are connected in series to the snubber capacitor 9C,
The voltage of the snubber capacitor 9C is 2 of the voltage E of the DC power supply 2.
It will be double charged.

FIG. 8 is an operation waveform diagram showing the operation state of each part of the operation circuit shown in FIG. 7. FIG. 8 shows the current I ₉ of the snubber capacitor 9C, the voltage V _{9 of the} snubber capacitor 9C and the positive side. Changes in the current I ₄ of the semiconductor switch 4 and FIG. 8 show changes in the current I ₆ of the negative side semiconductor switch 6 and the voltage V ₆ of the negative side semiconductor switch 6, respectively.

As is apparent from FIG. 8, when the positive side semiconductor switch 4 is turned on (at time t ₁ ) and the charging current I ₉ flows through the snubber capacitor 9C, the voltage V ₉ thereof changes to 2V.
The voltage rises to E (E is the voltage of the DC power supply 2). This voltage V
Along with the rise of ₉ , the voltage V _{6 of the} negative side semiconductor switch 6 connecting the snubber capacitor 9C in parallel is 2 of the same value.
Rise to E. Therefore, in the second conventional example circuit of FIG. 6, the positive-side semiconductor switch 4 and the negative-side semiconductor switch 6 must use an element having a breakdown voltage that is at least twice the voltage E of the DC power supply 2.

Since a high-voltage semiconductor switch element generally has a high saturation voltage and its generated loss is large, if a power converter is configured with the high-voltage semiconductor switch element, the conversion efficiency is lowered and heat generated by the generated loss is removed. Therefore, a heat dissipation device or a cooling device is required, and the power conversion device becomes large in size. Furthermore, since the switching characteristics of high-voltage semiconductor switching elements are not as good as those of low-voltage switching elements, the capacities of the suppression reactor and snubber capacitors must be increased, which also has the drawback of further increasing the size of the device. .

Therefore, an object of the present invention is to suppress the snubber circuit voltage when the energy absorbed by the snubber circuit is regenerated to the power source during the operation of the power conversion device and reduce the loss generated in the circuit to reduce the breakdown voltage of the semiconductor switch. It is to enable the use of and the simplification of the heat dissipation device.

[0016]

In order to achieve the above object, the snubber energy recovery circuit of the power converter of the present invention has a snubber composed of a series circuit of a snubber capacitor and a snubber diode connected in parallel. A plurality of semiconductor switches are connected in series and connected between the positive and negative electrodes of a DC power source, and each of the snubber diodes in the power conversion device that performs power conversion by the ON / OFF operation of the semiconductor switches includes an auxiliary diode and an auxiliary reactor. Between the energy absorption circuits, which are configured by series connection with an auxiliary capacitor, are separately connected in parallel, and between any connection point of the energy absorption circuit belonging to the positive side of the DC power supply and the negative side of the DC power supply. Is connected to a first energy recovery circuit constituted by a series connection of a first regenerative diode and a first regenerative reactor, and A second regenerative diode and a second regenerative reactor connected in series between any connection point of the energy absorption circuit belonging to the negative side of the DC power source and the positive side of the DC power source. In a snubber energy recovery circuit of a power conversion device to which two energy recovery circuits are connected, a voltage clamp circuit configured by a series connection of a clamp capacitor and a clamp diode is separately connected in parallel to each snubber capacitor, and A third energy recovery circuit composed of a series connection of a third regenerative diode and a third regenerative reactor is connected between the clamp capacitor of the voltage clamp circuit belonging to the positive side and the negative side of the DC power supply. And the positive side of the DC power source and the clamp capacitor of the voltage clamp circuit belonging to the negative side of the DC power source. Between the side, it is assumed that connects the fourth energy recovery circuit constituted by series connection of a fourth regenerative diode and fourth regeneration reactor.

Alternatively, a voltage clamp circuit composed of a series connection of a clamp capacitor and a clamp diode is separately connected in parallel to each snubber capacitor, and a clamp capacitor of the voltage clamp circuit belonging to the positive side of the DC power supply is connected to the clamp capacitor. The first regenerative reactor that constitutes the first energy recovery circuit is connected via a fifth regenerative diode, and the clamp capacitor of the voltage clamp circuit that belongs to the negative side of the DC power source and the second It is assumed that the second regenerative reactor that constitutes the energy recovery circuit is connected via the sixth regenerative diode.

Alternatively, a voltage clamp circuit composed of a series connection of a clamp capacitor and a clamp diode is separately connected in parallel to each of the snubber capacitors, and any connection of the energy absorption circuit belonging to the positive side of the DC power supply is made. A fifth energy recovery circuit constituted by a series connection of a seventh regenerative diode and a first center tap type reactor is connected between the point and the negative electrode side of the DC power supply, and the first center tap type reactor is connected. A ninth regenerative diode is connected between the center tap and the clamp capacitor of the voltage clamp circuit that belongs to the positive side of the DC power supply, and any of the energy absorption circuits that belong to the negative side of the DC power supply. Of the eighth regenerative diode and the second center tap type reactor between the connection point of the Connect the sixth energy recovery circuit constituted by column connection, between the second center-tapped reactor of the clamp capacitor of said voltage clamping circuit with center tap belongs to the negative electrode side of the DC power supply, first
A regenerative diode of 0 shall be connected.

Alternatively, a voltage clamp circuit composed of a series connection of a clamp capacitor and a clamp diode is separately connected in parallel to each of the semiconductor switches, and a clamp capacitor of the voltage clamp circuit belonging to the positive side of the DC power supply is used. The third energy recovery circuit configured by connecting a third regenerative diode and a third regenerative reactor in series is connected between the negative side of the DC power supply and belongs to the negative side of the DC power supply. The fourth energy recovery circuit configured by connecting a fourth regenerative diode and a fourth regenerative reactor in series is connected between the clamp capacitor of the voltage clamp circuit and the positive electrode side of the DC power supply.

Alternatively, a voltage clamp circuit constituted by connecting a clamp capacitor and a clamp diode in series is separately connected in parallel to each of the semiconductor switches, and the clamp capacitor of the voltage clamp circuit belonging to the positive side of the DC power supply is connected to the clamp capacitor. The first regenerative reactor that constitutes the first energy recovery circuit is connected via the fifth regenerative diode, and the clamp capacitor of the voltage clamp circuit that belongs to the negative side of the DC power supply and the second The second regenerative reactor that constitutes the energy recovery circuit is connected through the sixth regenerative diode.

Alternatively, a voltage clamp circuit composed of a series connection of a clamp capacitor and a clamp diode is separately connected in parallel to each of the semiconductor switches, and any connection of the energy absorption circuit belonging to the positive side of the DC power supply is made. The fifth energy recovery circuit, which is configured by connecting a seventh regenerative diode and a first center tap type reactor in series, is connected between the point and the negative electrode side of the DC power supply, and the first center tap type reactor is connected. Of the energy absorption circuit belonging to the negative side of the DC power supply, wherein the ninth regenerative diode is connected between the center tap and the clamp capacitor of the voltage clamp circuit belonging to the positive side of the DC power supply. An eighth regenerative diode and a second center tap type reactor are provided between an arbitrary connection point and the positive electrode side of the DC power supply. The sixth energy recovery circuit configured by the series connection is connected, and the sixth energy recovery circuit is connected between the center tap of the second center tap type reactor and the clamp capacitor of the voltage clamp circuit belonging to the negative side of the DC power supply. The tenth regenerative diode shall be connected.

[0022]

[Operation] A snubber capacitor is connected in parallel to the semiconductor switch, and the energy stored in the suppression reactor is stored in this snubber capacitor when the semiconductor switch is turned on and off. Although it is possible to regenerate the power to the power supply side by providing the energy absorption circuit and the energy recovery circuit, in the present invention, the snubber capacitor further comprises a clamp diode and a clamp capacitor connected in series. Connect the voltage clamp circuit in parallel. When the snubber capacitor voltage exceeds the clamp capacitor voltage, the clamp diode conducts, and the charge of the snubber capacitor is transferred to the clamp diode. That is, since the snubber capacitor voltage does not become higher than the clamp capacitor voltage, the semiconductor switch voltage connecting the snubber capacitors in parallel is also suppressed to the same value as the clamp capacitor voltage, and the high breakdown voltage as in the conventional circuit. It is not necessary to use the semiconductor switch of.

Further, the energy transferred to the clamp capacitor is regenerated to the power supply side via another diode connected between this clamp capacitor and the conventional energy recovery circuit, or is composed of a diode and a reactor connected in series. Another energy recovery circuit described above is connected to the clamp capacitor to regenerate the energy to the power supply side.
Alternatively, an energy recovery circuit configured by connecting a diode and a reactor with a center tap in series is installed instead of the conventional energy recovery circuit, and the center tap of the reactor with a center tap is connected to the clamp capacitor via another diode. Thus, the loss of the diode that constitutes the energy recovery circuit is reduced and the energy of the clamp capacitor is regenerated to the power supply side.

Further, in each of the circuits described above, the clamp capacitor is charged by changing the connection so that the voltage clamp circuit constituted by connecting the clamp diode and the clamp capacitor in series is connected in parallel with the semiconductor switch. Since the current at the time does not pass through the snubber diode,
The conduction loss that would otherwise occur with a snubber diode can be reduced.

[0025]

FIG. 1 is a circuit diagram showing a first embodiment of the present invention and corresponds to claim 1. The circuit of the first embodiment shown in FIG. 1 includes a clamp capacitor 31C and a clamp diode 3.
Positive side voltage clamp circuit 3 configured by series connection with 1D
1 is connected in parallel to the snubber capacitor 8C, and the third energy recovery circuit 42 constituted by the series connection of the third regenerative diode 42D and the third regenerative reactor 42L is connected to the clamp capacitor 31C and the negative side of the DC power supply 2. The negative voltage clamp circuit 41, which is formed by connecting the clamp capacitor 41C and the clamp diode 41D in series, is connected in parallel to the snubber capacitor 9C, and the fourth regenerative diode 32D and the fourth regenerative reactor 32L are inserted. The fourth energy recovery circuit 32 configured by series connection with the clamp capacitor 41C and the DC power source 2
6 is different from the circuit of the second conventional example described in FIG. 6 except that it is inserted between the positive electrode side and the positive electrode side. The description is omitted.

In FIG. 1, when the positive side semiconductor switch 4 is turned on, the DC power supply 2 → the positive side suppression reactor 3 → the positive side semiconductor switch 4 → the snubber diode 9D →
The snubber capacitor 9C is charged in the path from the snubber capacitor 9C to the negative electrode side suppression reactor 5. Here, when the voltage of the snubber capacitor 9C tries to exceed the voltage of the clamp capacitor 41C connected in parallel with the snubber capacitor 9C, the clamp diode 41D becomes conductive and is stored in the positive electrode side suppression reactor 3 and the negative electrode side suppression reactor 5. Energy is absorbed by the clamp capacitor 41C.

When the positive electrode side semiconductor switch 4 is turned off, the snubber capacitor 8C is in the path of the DC power source 2 → the positive electrode side suppressing reactor 3 → the snubber capacitor 8C → the snubber diode 8D → the negative electrode side semiconductor switch 6 → the negative electrode side suppressing reactor 5. Be charged. When the voltage of the snubber capacitor 8C tries to exceed the voltage of the clamp capacitor 31C connected in parallel to the snubber capacitor 8C, the clamp diode 31D becomes conductive, and is thus stored in the positive side suppression reactor 3 and the negative side suppression reactor 5. Energy is absorbed by the clamp capacitor 31C. The same operation as described above is performed when the negative semiconductor switch 6 is turned on or off.

The charge stored in the snubber capacitor 8C on the positive electrode side is transferred to the auxiliary capacitor 12C and then regenerated to the DC power source 2 via the first energy recovery circuit 23 on the negative electrode side, and the snubber capacitor 9C on the negative electrode side. The operation in which the electric charge stored in the circuit is transferred to the auxiliary capacitor 22C and then regenerated to the DC power supply 2 via the second energy recovery circuit 13 on the positive electrode side is the same as in the case of the second conventional example circuit already described in FIG. Since they are the same, the description of their operation will be omitted.

In the present invention, the operation of regenerating the electric charge stored in the clamp capacitor connected in parallel with the snubber capacitor to the DC power supply 2 is as follows. That is, while the negative-electrode side semiconductor switch 6 is off, the charge accumulated in the positive-side clamp capacitor 31C is clamp capacitor 31C → positive-side suppression reactor 3 → DC power supply 2
→ 3rd regeneration reactor 42L → 3rd regeneration diode 42
The energy is regenerated to the DC power supply 2 through the path of the D → clamp capacitor 31C. In addition, in this period, the current flowing through the third regenerative reactor 42L increases corresponding to the difference voltage between the voltage of the clamp capacitor 31C and the voltage E of the DC power supply 2, and reverses as the voltage of the clamp capacitor 31C decreases. It becomes a voltage and decreases.

Therefore, the positive side clamp capacitor 31
The voltage of C is almost clamped to the DC power supply voltage E. Next, while the negative electrode side semiconductor switch 6 is on, the current of the third regenerative reactor 42L is the third regenerative reactor 42L →
Third regeneration diode 42D → clamp diode 31D
-> Snubber diode 8D-> negative side semiconductor switch 6-> negative side suppression reactor 5-> recirculation in the path of the third regenerative reactor 42L. The operation of regenerating the electric charge stored in the clamp capacitor 41C on the negative electrode side to the DC power supply 2 is also performed by the same operation as described above.

FIG. 2 is an operation circuit diagram showing a current path when the first embodiment circuit of FIG. 1 operates. Only the necessary circuit elements in the first embodiment circuit of FIG. 1 are illustrated. ing.
In the circuit of FIG. 2, when the positive-side semiconductor switch 4 is turned on while the load current _IO is flowing back from the antiparallel diode of the negative-side semiconductor switch 6 toward the AC terminal 7, the negative-side semiconductor switch 6 is turned on. The anti-parallel diode is turned off, and the load current I _O is diverted to the path from the positive side semiconductor switch 4 to the AC terminal 7, and at this time, the snubber capacitor 9C is charged. At the time of this charging, since the DC power supply 2, the positive electrode side suppression reactor 3, and the negative electrode side suppression reactor 5 are connected in series to the snubber capacitor 9C, if the voltage of the snubber capacitor 9C tries to exceed the voltage of the clamp capacitor 41C, The clamp diode 41D becomes conductive and suppresses the voltage rise of the snubber capacitor 9C.

FIG. 3 is an operation waveform diagram showing the operation state of each part of the operation circuit shown in FIG. 2. FIG. 3 shows the current I ₉ of the snubber capacitor 9C, the voltage V _{9 of the} snubber capacitor 9C and the clamp capacitor. Change in current I ₄₁ of 41C,
FIG. 3 shows changes in the current I ₆ of the negative side semiconductor switch 6 and the voltage V ₆ of the negative side semiconductor switch 6, respectively.

As is apparent from FIG. 3, when the positive side semiconductor switch 4 is turned on (at time t ₁₁ ) and the charging current I ₉ flows to the snubber capacitor 9C, the voltage V ₉ thereof also rises, but this voltage V ₉ also rises. ₉ reaches the voltage of the clamp capacitor 41C and (t ₁₂ time), clamp diode 41
D becomes conductive and a current I ₄₁ flows to the clamp capacitor 41C, and the voltage V ₉ of C of the snubber capacitor 9C is suppressed to a value E + ΔV which is slightly higher than the DC power supply voltage E.

FIG. 4 is a circuit diagram showing a second embodiment of the present invention and corresponds to claim 2. In the circuit of the second embodiment of FIG. 4, the clamp capacitor 31C and the first regenerative reactor 23L are coupled via the fifth regenerative diode 43D, and the clamp capacitor 41C and the second regenerative reactor 13L are connected to the sixth regenerative reactor 13L. It is different from the above-described first embodiment circuit of FIG. 1 in that it is coupled through the regenerative diode 33D, but other than that, the operation is the same as that of the first embodiment circuit of FIG. The detailed description of is omitted.

In the second embodiment circuit of FIG. 4, when the voltage of the snubber capacitor 8C rises, the clamp diode 3
Charging of the clamp capacitor 31C by conduction of 1D is the same as in the above case. Further, while the positive side semiconductor switch 4 is on, the electric charge of the snubber capacitor 8C is transferred to the auxiliary capacitor 12C through the above-described path, then the positive side semiconductor switch 4 is turned off and the negative side semiconductor switch 6 is turned on. During the period, the charge of the auxiliary capacitor 12C is changed from the auxiliary capacitor 12C to the negative electrode side semiconductor switch 6
Negative electrode side suppression reactor 5 → 1st regenerative reactor 23L →
The first regenerative diode 23D is discharged through the path of the auxiliary capacitor 12C to increase the current of the first regenerative reactor 23L.

Next, when the negative-side semiconductor switch 6 is turned off, the current of the first regenerative reactor 23L changes from the first regenerative reactor 23L to the fifth regenerative diode 43D to the clamp capacitor 31C to the positive side suppression reactor 3 to the DC power supply 2
It flows in the path of the first regenerative reactor 23L, discharges the electric charge of the clamp capacitor 31C, and regenerates the energy of the first regenerative reactor 23L to the DC power supply 2. Further, during this period, the current of the first regenerative reactor 23L increases due to the difference voltage between the voltage of the clamp capacitor 31C and the voltage of the DC power supply 2, and the reverse voltage is applied and decreases as the voltage of the clamp capacitor 31C decreases. As a result, the voltage of the clamp capacitor 31C is clamped to a value substantially equal to the voltage E of the DC power supply 2.

The charges accumulated in the snubber capacitor 9C on the negative electrode side and the clamp capacitor 41C are regenerated to the DC power source 2 by the operations of the positive electrode side semiconductor switch 4 and the negative electrode side semiconductor switch 6 being opposite to those described above. . FIG. 9 is a circuit diagram showing a third embodiment of the present invention and corresponds to claim 3. The circuit of the third embodiment shown in FIG. 9 corresponds to the circuit of the second embodiment described in FIG.
The following points are different from the embodiment circuit. That is, the first
Instead of the energy recovery circuit 23, a fifth energy recovery circuit 61 configured by a series connection of a seventh regenerative diode 61D and a first center tap type reactor 61L is connected between the positive side energy absorption circuit 12 and the negative side. Connecting the center tap of the first center tap type reactor 61L and the clamp capacitor 31C via a ninth regenerative diode 62D, and instead of the second energy recovery circuit 13, an eighth regenerative diode 51D. The sixth energy recovery circuit 51 configured by series connection with the second center tap type reactor 51L is connected between the negative side energy absorption circuit 22 and the positive side, and the center tap of the second center tap type reactor 51L and the above The clamp capacitor 41C is connected via the tenth regenerative diode 52D. , Since all other is the same as the second embodiment circuit of Figure 4 described above, description of the same portions will be omitted.

The energy stored in the snubber capacitor 8C according to the operation of the positive side semiconductor switch 4 is transferred to the auxiliary capacitor 12C when the positive side semiconductor switch 4 is turned on, and then the positive side semiconductor switch 4 is turned off and the negative side semiconductor switch 4 is turned off. While the switch 6 is on, this energy is supplied to the auxiliary capacitor 12C → the negative side semiconductor switch 6 → the negative side suppression reactor 5 → the first center tap type reactor 61.
It is discharged from the terminal A of L to C → the seventh regenerative diode 61D → the auxiliary capacitor 12C. At this time, since the discharge current of the auxiliary capacitor 12C can be suppressed by increasing the inductance between the terminals A and C of the first center tap type reactor 61L, it is possible to reduce the loss generated in the seventh regenerative diode 61D.

Further, the charge accumulated in the clamp capacitor 31C when the positive-side semiconductor switch 4 is turned off is the clamp capacitor 31C → the positive-side suppression reactor 3 → the DC power source 1 → the first center tap type reactor 61L.
From the terminal A to B → the ninth regeneration diode 62D → the clamp capacitor 31C. At this time, by setting the inductance between the terminals A and B of the first center tap type reactor 61L to be smaller than the inductance between the terminals A and C, the voltage fluctuation of the clamp capacitor 31C can be suppressed small. The charge of the auxiliary capacitor 22C on the negative electrode side is discharged through the sixth energy recovery circuit 51 provided on the positive electrode side, as described above, so that the second center tap type that constitutes the sixth energy recovery circuit 51 is used. If the discharge current is suppressed by increasing the inductance between the terminals A and C of the reactor 51L, the current flowing through the eighth regenerative diode 51D decreases, so that the generated loss can be reduced and at the same time, the second center tap. By making the inductance between the terminals A and B of the expression reactor 51L smaller than the inductance between the terminals A and C, the voltage fluctuation of the clamp capacitor 41C can be suppressed small.

FIG. 10 is a circuit diagram showing a fourth embodiment of the present invention and corresponds to claim 4. In the fourth embodiment circuit, the connection position of the positive voltage clamp circuit 31 (consisting of a series connection of a clamp capacitor 31C and a clamp diode 31D) in the first embodiment circuit described above with reference to FIG. The configuration is such that the semiconductor switch 4 is connected in parallel, and the negative side voltage clamp circuit 41 (consisting of a series connection of the clamp capacitor 41C and the clamp diode 41D) is also changed to the negative side semiconductor switch 6 by changing the connection position. It is different in that it is configured to be connected in parallel, and is otherwise the same as the circuit of the first embodiment of FIG. 1, and therefore the description of the same parts will be omitted.

In the fourth embodiment circuit of FIG. 10, when the positive side semiconductor switch 4 is turned off, the current flowing through the positive side semiconductor switch 4 is the snubber capacitor 8.
Since the snubber diode 8D is charged by flowing through the path of C → snubber diode 8D, the voltage of the snubber capacitor 8C gradually rises. When this voltage reaches the voltage of clamp capacitor 31C, snubber capacitor 8
The current flowing through C is changed to the path from the clamp capacitor 31C to the clamp diode 31D. The diode that causes a loss with the current at this time is only the clamp diode 31D (in the first embodiment circuit of FIG. 1, a current flows through the clamp diode 31D and the snubber diode 8D, and both generate a loss). The conduction loss during this period is halved.

The semiconductor switch 6 on the negative side is turned off and the clamp capacitor 41C → the clamp diode 41D.
Even when a current flows through the path of (3), similarly, only the clamp diode 41D causes a loss, so the generated loss is halved.
FIG. 11 is a circuit diagram showing a fifth embodiment of the present invention and corresponds to claim 5. This fifth embodiment circuit is a positive voltage clamp circuit 31 in the second embodiment circuit described above with reference to FIG.
(Clamp capacitor 31C and clamp diode 31
D is connected in series) and the connection position is changed to a parallel connection to the positive-side semiconductor switch 4.
Negative voltage clamp circuit 41 (clamp capacitor 41
C is also connected in series) and the clamp diode 41D is also different in that the connection position is similarly changed and the negative side semiconductor switch 6 is connected in parallel. Since it is the same as the circuit of the second embodiment, description of the same parts will be omitted. Further, the operation associated with the change of the connection position of the positive voltage clamp circuit 31 and the change of the connection position of the negative voltage clamp circuit 41 is the same as that of the fourth embodiment circuit described above with reference to FIG. The description of the connection changing part is also omitted.

FIG. 12 is a circuit diagram showing a sixth embodiment of the present invention and corresponds to claim 6. In this sixth embodiment circuit, the connection position of the positive voltage clamp circuit 31 (consisting of a series connection of a clamp capacitor 31C and a clamp diode 31D) in the third embodiment circuit described above with reference to FIG. The configuration is such that the semiconductor switch 4 is connected in parallel, and the negative side voltage clamp circuit 41 (consisting of a series connection of the clamp capacitor 41C and the clamp diode 41D) is also changed to the negative side semiconductor switch 6 by changing the connection position. It is different in that it is configured to be connected in parallel, and is otherwise the same as the circuit of the third embodiment of FIG. 9, so the description of the same parts will be omitted. Further, the operation associated with the change of the connection position of the positive voltage clamp circuit 31 and the change of the connection position of the negative voltage clamp circuit 41 is the same as that of the fourth embodiment circuit described above with reference to FIG. The description of the connection changing part is also omitted.

[0044]

According to the present invention, the voltage clamp circuit constituted by the series connection of the clamp capacitor and the clamp diode is connected in parallel to the snubber capacitor which is connected in parallel to the semiconductor switch which constitutes the power conversion device. When the semiconductor switch turns on and off, charges accumulate in the snubber capacitor, and when the voltage rises above the clamp capacitor voltage, the clamp capacitor is charged via the clamp diode, so the snubber capacitor voltage rises. Suppressed. Here, the stored charge of the snubber capacitor is regenerated to the DC power source side via the energy absorption circuit and the energy recovery circuit, but the stored charge of the clamp capacitor is also recovered via the regenerative diode and the energy recovery circuit or another energy recovery circuit. It is regenerated to the DC power supply side through the circuit. That is, the increase in the snubber capacitor voltage is suppressed by the clamp capacitor, so that it is not necessary to increase the breakdown voltage of the semiconductor switch in which the snubber capacitors are connected in parallel. Therefore, the loss due to the ON / OFF operation of the semiconductor switch is reduced, the conversion efficiency is improved, and the heat generation is reduced, so that the cooling device for heat radiation can be simplified. Furthermore, since the stored energy of the snubber capacitor and clamp capacitor is regenerated to the DC power supply side, the effect of further improving the conversion efficiency of the device,
Combined with the effect of reducing heat generation.

Alternatively, if the energy recovery circuit is configured by connecting a center tap type reactor and a diode in series and the inductance of the center tap type reactor is increased, the current of the energy recovery circuit is suppressed. The effect that can reduce the loss generated in the diode that constitutes the energy recovery circuit is obtained, and if the center tap of the center tap type reactor and the clamp capacitor are connected through another diode, the voltage of the clamp capacitor The effect that the fluctuation can be suppressed small is obtained.

Alternatively, if the connection of the voltage clamp circuit, which is composed of a clamp capacitor and a clamp diode connected in series, is changed so as to be connected in parallel with the semiconductor switch, the current that flows when the clamp capacitor is charged is changed. Since the loss is generated only in the clamp diode and the loss generated in the snubber diode is eliminated, the loss is further reduced, the power conversion efficiency is improved, and the heat dissipation device can be simplified.

[Brief description of drawings]

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

FIG. 2 is an operation circuit diagram showing a current path when the circuit of the first embodiment of FIG. 1 operates.

FIG. 3 is an operation waveform diagram showing an operation state of each part of the operation circuit of FIG.

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

FIG. 5 is a circuit diagram showing a first conventional example for one phase of an inverter.

FIG. 6 is a circuit diagram showing a second conventional example for one phase of an inverter.

FIG. 7 is an operation circuit diagram showing a current path when the second conventional example circuit of FIG. 6 operates.

8 is an operation waveform diagram showing an operation state of each part of the operation circuit of FIG.

FIG. 9 is a circuit diagram showing a third embodiment of the present invention.

FIG. 10 is a circuit diagram showing a fourth embodiment of the present invention.

FIG. 11 is a circuit diagram showing a fifth embodiment of the present invention.

FIG. 12 is a circuit diagram showing a sixth embodiment of the present invention.

[Explanation of symbols]

 2 DC power supply 3 Positive side suppression reactor 4 Positive side semiconductor switch 5 Negative side suppression reactor 6 Negative side semiconductor switch 7 AC terminal 8C, 9C Snubber capacitor 8D, 9D Snubber diode 11 Positive side snubber 12 Positive side energy absorption circuit 12C, 22C Auxiliary Capacitor 12D, 22D Auxiliary diode 12L, 22L Auxiliary reactor 13 Second energy recovery circuit 13D First regenerative diode 13L First regenerative reactor 21 Negative side snubber 22 Negative side energy absorption circuit 23 First energy recovery circuit 23D First regenerative diode 23L First 1st regeneration reactor 31 Positive side voltage clamp circuit 31C, 41C Clamp capacitor 31D, 41D Clamp diode 32 4th energy recovery circuit 32D 4th regeneration diode 32L 4th Raw reactor 33D 6th regenerative diode 41 Negative side voltage clamp circuit 42 3rd energy recovery circuit 42D 3rd regenerative diode 42L 3rd regenerative reactor 43D 5th regenerative diode 51 6th energy recovery circuit 51D 8th regenerative diode 51L 2nd center tap Type reactor 52D 10th regenerative diode 61 5th energy recovery circuit 61D 7th regenerative diode 61L 1st center tap type reactor 62D 9th regenerative diode

Claims (6)

[Claims] 1. A semiconductor switch having a snubber capacitor and a snubber diode connected in parallel is connected in series, and a plurality of semiconductor switches each having a snubber connected in parallel are connected in series between the positive and negative electrodes of a DC power supply to turn on the semiconductor switch. -Each of the snubber diodes in the power conversion device that performs power conversion in the off operation is separately connected in parallel with an energy absorption circuit that is configured by a series connection of an auxiliary diode, an auxiliary reactor, and an auxiliary capacitor. The first regenerative diode and the first regenerative diode are provided between an arbitrary connection point of the energy absorption circuit belonging to the positive electrode side and the negative electrode side of the DC power supply.
Connecting a first energy recovery circuit configured by series connection with a regenerative reactor of, and between any connection point of the energy absorption circuit belonging to the negative side of the DC power supply and the positive side of the DC power supply. , In a snubber energy recovery circuit of a power conversion device that is connected to a second energy recovery circuit configured by connecting a second regenerative diode and a second regenerative reactor in series, a clamp capacitor and a clamp diode are connected in series. And a third regenerative diode between the clamp capacitor of the voltage clamp circuit belonging to the positive side of the DC power supply and the negative side of the DC power supply. And the third
Connecting a third energy recovery circuit configured by series connection with the regenerative reactor, and between the clamp capacitor of the voltage clamp circuit belonging to the negative side of the DC power source and the positive side of the DC power source. A snubber energy recovery circuit for a power conversion device, characterized in that a fourth energy recovery circuit configured by connecting four regenerative diodes and a fourth regenerative reactor in series is connected. 2. A semiconductor switch having a snubber capacitor and a snubber diode connected in parallel is connected in series, and a plurality of semiconductor switches connected in parallel are connected between the positive and negative electrodes of a DC power supply to turn on the semiconductor switch. -Each of the snubber diodes in the power conversion device that performs power conversion in the off operation is separately connected in parallel with an energy absorption circuit that is configured by a series connection of an auxiliary diode, an auxiliary reactor, and an auxiliary capacitor. The first regenerative diode and the first regenerative diode are provided between an arbitrary connection point of the energy absorption circuit belonging to the positive electrode side and the negative electrode side of the DC power supply.
Connecting a first energy recovery circuit configured by series connection with a regenerative reactor of, and between any connection point of the energy absorption circuit belonging to the negative side of the DC power supply and the positive side of the DC power supply. , In a snubber energy recovery circuit of a power conversion device that is connected to a second energy recovery circuit configured by connecting a second regenerative diode and a second regenerative reactor in series, a clamp capacitor and a clamp diode are connected in series. And a first regenerative reactor that constitutes the first energy recovery circuit and a clamp capacitor of the voltage clamp circuit that belongs to the positive electrode side of the DC power supply. Is connected via a fifth regenerative diode and belongs to the negative side of the DC power supply. A snubber energy recovery circuit for a power conversion device, characterized in that a clamp capacitor of a power recovery circuit and a second regenerative reactor forming the second energy recovery circuit are connected via a sixth regenerative diode. 3. A semiconductor switch comprising a series circuit of a snubber capacitor and a snubber diode, wherein a plurality of semiconductor switches each having a snubber connected in parallel are connected in series and connected between the positive and negative electrodes of a DC power source to turn on the semiconductor switch. A power conversion device in which an energy absorption circuit configured by serial connection of an auxiliary diode, an auxiliary reactor, and an auxiliary capacitor is separately connected in parallel to each of the snubber diodes in the power conversion device that performs power conversion in the off operation. In the snubber energy recovery circuit, a voltage clamp circuit composed of a series connection of a clamp capacitor and a clamp diode is separately connected in parallel to each of the snubber capacitors, and any one of the energy absorption circuits belonging to the positive side of the DC power supply is connected. A regenerative diode between the connection point and the negative side of the DC power supply. And the first center tap type reactor connected in series
An energy recovery circuit is connected, a ninth regenerative diode is connected between the center tap of the first center tap type reactor and the clamp capacitor of the voltage clamp circuit belonging to the positive side of the DC power supply, and Between the optional connection point of the energy absorption circuit belonging to the negative side of the DC power source and the positive side of the DC power source, the eighth regenerative diode and the second center tap type reactor are connected in series. A sixth energy recovery circuit is connected, and a tenth regenerative diode is connected between the center tap of the second center tap type reactor and the clamp capacitor of the voltage clamp circuit belonging to the negative side of the DC power supply. A snubber energy recovery circuit for a power conversion device. 4. A semiconductor switch comprising a series circuit of a snubber capacitor and a snubber diode, wherein a plurality of semiconductor switches each having a snubber connected in parallel are connected in series and connected between the positive and negative electrodes of a DC power supply to turn on the semiconductor switch. -Each of the snubber diodes in the power conversion device that performs power conversion in the off operation is separately connected in parallel with an energy absorption circuit that is configured by a series connection of an auxiliary diode, an auxiliary reactor, and an auxiliary capacitor. The first regenerative diode and the first regenerative diode are provided between an arbitrary connection point of the energy absorption circuit belonging to the positive electrode side and the negative electrode side of the DC power supply.
Connecting a first energy recovery circuit configured by series connection with a regenerative reactor of, and between any connection point of the energy absorption circuit belonging to the negative side of the DC power supply and the positive side of the DC power supply. , In a snubber energy recovery circuit of a power conversion device that is connected to a second energy recovery circuit configured by connecting a second regenerative diode and a second regenerative reactor in series, a clamp capacitor and a clamp diode are connected in series. And a third regenerative diode between the clamp capacitor of the voltage clamp circuit, which belongs to the positive side of the DC power supply, and the negative side of the DC power supply. And a third regenerative reactor are connected in series to connect the third energy recovery circuit, and the negative of the DC power supply is connected. Between the clamp capacitor of the voltage clamp circuit belonging to the pole side and the positive electrode side of the DC power supply, the fourth energy recovery circuit configured by the series connection of a fourth regenerative diode and a fourth regenerative reactor is provided. A snubber energy recovery circuit for a power conversion device, which is connected. 5. A semiconductor switch comprising a series circuit of a snubber capacitor and a snubber diode, wherein a plurality of semiconductor switches connected in parallel are connected in series and connected between the positive and negative electrodes of a DC power source to turn on the semiconductor switch. -Each of the snubber diodes in the power conversion device that performs power conversion in the off operation is separately connected in parallel with an energy absorption circuit that is configured by a series connection of an auxiliary diode, an auxiliary reactor, and an auxiliary capacitor. The first regenerative diode and the first regenerative diode are provided between an arbitrary connection point of the energy absorption circuit belonging to the positive electrode side and the negative electrode side of the DC power supply.
Connecting a first energy recovery circuit configured by series connection with a regenerative reactor of, and between any connection point of the energy absorption circuit belonging to the negative side of the DC power supply and the positive side of the DC power supply. , In a snubber energy recovery circuit of a power conversion device that is connected to a second energy recovery circuit configured by connecting a second regenerative diode and a second regenerative reactor in series, a clamp capacitor and a clamp diode are connected in series. The voltage clamp circuit is separately connected in parallel to each of the semiconductor switches, and the clamp capacitor of the voltage clamp circuit belonging to the positive side of the DC power source and the first
A first regenerative reactor that constitutes an energy recovery circuit is connected via the fifth regenerative diode, and a clamp capacitor of the voltage clamp circuit that belongs to the negative side of the DC power supply and the second energy recovery circuit. The snubber energy recovery circuit of the power conversion device, characterized in that the second regenerative reactor constituting the above is connected via the sixth regenerative diode. 6. A semiconductor switch comprising a series circuit of a snubber capacitor and a snubber diode is connected in parallel, and a plurality of semiconductor switches connected in series are connected in series between the positive and negative electrodes of a DC power source to turn on the semiconductor switch. A power conversion device in which an energy absorption circuit configured by serial connection of an auxiliary diode, an auxiliary reactor, and an auxiliary capacitor is separately connected in parallel to each of the snubber diodes in the power conversion device that performs power conversion in the off operation. In the snubber energy recovery circuit, a voltage clamp circuit composed of a series connection of a clamp capacitor and a clamp diode is separately connected in parallel to each of the semiconductor switches, and any of the energy absorption circuits belonging to the positive side of the DC power supply is connected. Between the connection point of and the negative side of the DC power source, a seventh regenerative diode The fifth energy recovery circuit configured by series connection with the first center tap type reactor is connected, and the center tap of the first center tap type reactor and the voltage clamp circuit belonging to the positive side of the DC power source are connected. The ninth regenerative diode is connected between the clamp capacitor and an eighth connection between an arbitrary connection point of the energy absorption circuit belonging to the negative side of the DC power supply and the positive side of the DC power supply.
Connected to the sixth energy recovery circuit constituted by series connection of the regenerative diode and the second center tap type reactor, and belonging to the center tap of the second center tap type reactor and the negative side of the DC power source. A snubber energy recovery circuit for a power conversion device, wherein the tenth regenerative diode is connected between a clamp capacitor of a voltage clamp circuit and the clamp capacitor.