JP2001238431A - Semiconductor power converter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a semiconductor power converter, which can relieve the rising rate of a collector voltage rise produced, when a semiconductor power transducer is turned off to suppress a peak value of a high voltage applied between its collector and emitter, and further can suppress the increase of a collector loss as low as possible. SOLUTION: This semiconductor power converter has an IGBT 1, which is power transducer, provided in each arm connected between a DC power supply and a load, and whose collector and emitter are connected in series to the arm, a capacitor 5 connected between the collector and gate of the IGBT 1 and supplies a current, corresponding to a change rate of a voltage between the collector and emitter and an auxiliary DC power supply 7 which is connected in parallel to the capacitor 5 via a buffer diode 6. If a voltage, obtained by adding the forward voltage drop of the buffer dioded 6 to the collector side voltage of the capacitor 5, exceeds the output voltage of the auxiliary DC power supply 7, a current is supplied to the gate via the capacitor 5.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor power conversion device, and more particularly, to a semiconductor power conversion device for performing DC-AC power conversion, in which a semiconductor power conversion device is disposed on each arm and the semiconductor power conversion device is turned off. The present invention relates to a semiconductor power conversion device provided with a means for effectively suppressing a high voltage that sometimes occurs.

[0002]

2. Description of the Related Art Generally, a semiconductor power converter for performing DC-AC power conversion is connected between a DC power supply and an AC load, converts DC power output from the DC power supply into AC power, and converts the DC power to AC power. In the case where the AC load constitutes a three-phase AC load, the AC load is constituted by six arms in each of which a semiconductor power conversion element is arranged.
At this time, IGBTs (insulated gate bipolar transistors) are often used for the semiconductor power conversion elements arranged in the six arms.

FIG. 11 is a circuit diagram showing an example of a configuration of a main part of a known semiconductor power conversion device, in which DC power output from a DC power supply is converted into three-phase AC power and converted to an AC load. It is an example of supply.

In FIG. 11, reference numeral 50 denotes a semiconductor power converter, 51 denotes a DC power supply, 52 denotes a three-phase AC motor (three-phase AC load), and 53 denotes an inductor. In this case, the semiconductor power converter 50 includes six arms 54 ₁ , 54 ₂ , 54
₃ , 54 ₄ , 54 ₅ , 54 ₆ and six arms 54 ₁
Semiconductor power converter device 55 to each of the 54 _{6 1,} 5
5 _2, 55 _3, 55 _4, 55 _5, 55 ₆ are disposed.

[0005] The semiconductor power conversion device 50 is provided between the first input and the second input terminal, connected in series: a first circuit arm 54 ₁ and the arm ₅₄₂ are connected in series, the arm ₅₄₃ and the arm 54 ₄ Arm 54 ₅ and arm 54 ₆
Are connected in parallel with a third circuit. The first input terminal of the semiconductor power conversion device 50 is connected to the positive terminal of the DC power supply 51 through the inductor 53, and the second input terminal of the semiconductor power conversion device 50 is directly connected to the negative terminal of the DC power supply 51. The three-phase AC motor 52 includes three windings 56 ₁ , 56 ₂ , one end of which is commonly connected at a neutral point O,
Made 56 _3, the winding 56 ₁ and the other end is connected to a first output terminal is the connection point between the arm 54 ₁ and the arm ₅₄₂ of the first circuit, the winding 56 ₂ and the other end of the second circuit is connected to the second output terminal is the connection point between the arm ₅₄₃ and the arm 54 _4,
Arm 54 of the third circuit and the other end of the winding 56 _{3 5} and the arm 5
4 is connected to the third output terminal is a connection point between the _6.

The semiconductor power conversion device 50 having the above configuration operates as follows. A drive signal by the drive signal outputted from a driving source not shown is supplied to the six semiconductor power conversion elements 55 ₁ to 55 ₆ in FIG. 11, six semiconductor power conversion elements 55 ₁ to 55 ₆ at a predetermined cycle When the power is turned on and off alternately, the DC output from the DC power supply 51 flows through the turned-on semiconductor power conversion element, thereby generating three-phase AC at the first output terminal to the third output terminal. It is supplied to the motor 52. At this time, 6
One of the semiconductor power conversion elements 55 ₁ to drive signals for driving the 55 _6, PWM in (pulse width modulation) or PAM (pulse amplitude modulation) type signal, the semiconductor power conversion elements 55 _1, 55 ₂ of the first circuit at the same time Without being turned on, similarly, the semiconductor power conversion elements 55 ₃ , 55
Power conversion device 55 of the _fourth and third circuit _5, 55 ₆ to be turned on at the same time each well.

[0007] Next, FIG. 12, the known semiconductor power converter 50 six semiconductor power conversion device 55 IGBT ₁ to 55 ₆ respectively disposed on the arm 54 ₁ to 54 ₆
FIG. 4 is a circuit diagram showing a configuration of a power conversion circuit section of one arm when using an active snubber, in which an active snubber for suppressing an overvoltage applied when the IGBT is turned off is connected. And such a semiconductor power conversion device 5
0 is, for example, IEEE Power Electro
n Spec Conf Vol. 1995, No1
1. "The Series Connection
of IGBTwith Optimized Vo
Stage Sharing in the Switch
Ching Transient ".

[0008] In FIG. 12, 61, the gate G and the collector C and IGBT having an emitter E, 62 is freewheeling diode, 63 clamp capacitor, 64 is a gate resistor 65 is pulsed driving signal source, 66 ₁ drive signal positive supply for source 66 ₂ is a negative electrode power drive signal source.

The IGBT 61 has a collector C connected to the positive electrode of a DC power supply (not shown in FIG. 12), an emitter E connected to the negative electrode of the DC power supply, and a gate G connected to one end of the gate resistor 64. Is done. Reflux diode 6
No. 2 has an anode connected to the emitter E and a cathode connected to the collector C. The clamping capacitor 63 is
It is connected between the collector C and the gate G. The output end of the pulse drive signal source 65 is connected to the other end of the gate resistor 64. The drive signal source positive power supply 66 ₁ has a positive terminal connected to the positive power supply terminal of the pulse drive signal source 65 and a negative terminal connected to the emitter E. Negative power supply 6 for drive signal source
6 _2, positive terminal is connected to the emitter E, the negative terminal is connected to the negative power supply terminal of the pulse driving signal source 65.

[0010] The power conversion circuit section having the above configuration operates as follows. When the drive signal of the positive polarity pulse is output from the pulse drive signal source 65, the drive signal is output to the gate resistor 6
4 to the gate G of the IGBT 61,
T61 turns on.

Next, when the output of the pulse drive signal source 65 changes from the positive pulse to the negative pulse, and the negative pulse is supplied to the gate G of the IGBT 61 through the gate resistor 64, the pulse is accumulated in the gate G of the IGBT 61. The positive charge that has been drawn out is extracted through the gate resistor 64 and the IGBT
61 turns off. At the time of this turn-off, a transient voltage is generated due to the inductance of the connection wiring from the positive terminal of the DC power supply to the negative terminal of the DC power supply through an arm including the IGBT 61 and another arm including the IGBT, and this transient voltage is generated. Is superimposed on the output DC voltage of the DC power supply, becomes a high voltage, and is applied between the collector and the emitter of the IGBT 61.

Here, when the clamping capacitor 63 is not connected between the collector and the gate of the IGBT 61, that is, when the active snubber is not connected, the high voltage is directly applied between the collector and the emitter of the IGBT 61. High voltage is the collector of IGBT61.
When the value greatly exceeds the withstand voltage between emitters, IG
BT61 will be destroyed.

On the other hand, when the clamp capacitor 63 is connected between the collector and the gate of the IGBT 61, that is, when the active snubber is connected, as in the power conversion circuit section having the above configuration, the high voltage Is applied and the collector voltage rises, a current corresponding to the collector voltage rise rate (dv / dt) flows into the gate G through the clamping capacitor 63, and the gate voltage becomes higher than the gate voltage when the active nava is not connected. Since it becomes higher, the collector voltage rise rate (dv / dt) becomes slower. Then, the collector voltage rise rate (dv / d
When t) becomes gentle, the peak value of the collector voltage is reduced, and it is possible to prevent a high voltage that greatly exceeds the collector-emitter breakdown voltage of the IGBT 61 from being applied between the collector and the emitter.

[0014]

The known power conversion circuit section has an IG connected to an active snubber.
The collector voltage rise rate (dv / dt) of the IGBT 61 when the BT 61 is turned off is moderate and considerable.
Although it is possible to prevent a high voltage that greatly exceeds the collector-emitter breakdown voltage of the IGBT 61 from being applied between the collector and the emitter, the collector voltage rise rate (dv /
Since dt) becomes gentle, the time until the collector current of the IGBT 61 starts to decrease becomes long, and the collector loss at the time of turn-off greatly increases.

The present invention has been made in view of such a technical background, and an object of the present invention is to increase a collector voltage rise rate (dv / dt) when a semiconductor power conversion element is turned off.
The present invention provides a semiconductor power conversion device in which the peak value of the high voltage applied between the collector and the emitter is suppressed by relaxing the peak value and the increase in the collector loss is minimized.

[0016]

In order to achieve the above object, a semiconductor power conversion device according to the present invention is a power conversion element disposed on each arm connecting a DC power supply and a load, comprising a collector and an emitter. I connected in series with the arm
Connected between the GBT and the collector and gate of the IGBT,
A capacitor for supplying a current corresponding to the collector-emitter voltage change rate to the gate, and an auxiliary DC power supply connected in parallel to the capacitor through a buffer diode;
When the voltage obtained by adding the forward voltage drop of the buffer diode to the voltage on the collector side of the capacitor exceeds the output voltage of the auxiliary DC power supply, a first configuration for supplying a current to the gate through the capacitor is provided.

In order to achieve the above object, a semiconductor power conversion device according to the present invention is a power conversion element arranged in each arm connecting a DC power supply and a load, wherein a collector and an emitter are connected to the arm. An IGBT connected in series, a voltage divider connected between the collector and the emitter, and a current connected between the voltage dividing point of the voltage divider and the gate of the IGBT, and supplying a current corresponding to the collector-emitter voltage change rate to the gate. A capacitor and an auxiliary DC power supply connected in parallel to the capacitor through a buffer diode, and when the voltage obtained by adding the forward voltage drop of the buffer diode to the voltage at the voltage dividing point of the capacitor exceeds the output voltage of the auxiliary DC power supply , A second configuration for supplying current to the gate through the capacitor.

Further, in order to achieve the above object, a semiconductor power conversion device according to the present invention is a power conversion element disposed on each arm connecting a DC power supply and a load, wherein a collector and an emitter are connected to the arm. IGBTs connected in series;
A voltage divider connected between the collector and the emitter, a capacitor connected between the voltage dividing point of the voltage divider and the gate of the IGBT and supplying a current corresponding to the collector-emitter voltage change rate to the gate, and a buffer diode connected to the capacitor And a DC power supply for the gate drive circuit connected in parallel through
When the voltage obtained by adding the forward voltage drop of the buffer diode to the voltage on the voltage dividing point side of the capacitor exceeds the output voltage of the DC power supply for the gate drive circuit, a third configuration for supplying a current to the gate through the capacitor is provided.

According to the first configuration, the capacitor is connected between the collector and the gate of the IGBT, and the series circuit of the auxiliary DC power supply and the buffer diode is connected in parallel with this capacitor. Since the collector voltage of the capacitor does not drop below a certain voltage, and the collector voltage of the capacitor cannot be prevented from exceeding the high voltage of the DC power supply, the time from when the IGBT starts to turn off until the collector current decreases. , The collector loss of the IGBT can be reduced.

According to the second structure, the first
In addition to the function achieved by the configuration described above, since one end of the capacitor is connected to the voltage dividing point of the voltage divider connected between the collector and the emitter, the collector voltage rise rate (dv / d
When t) is small, the collector voltage at which the clamp operation starts can be increased, and the collector voltage rise rate (d
When v / dt) is small, the occurrence of collector loss due to the clamp operation can be suppressed.

Further, according to the third configuration, in addition to the function achieved by the first configuration, a DC power supply for a gate drive circuit is used as an auxiliary DC power supply.
There is no need to newly prepare an auxiliary DC power supply, and the circuit of the semiconductor power conversion device can be simplified.

[0022]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a circuit diagram showing a first embodiment of a semiconductor power conversion device according to the present invention, and shows an example of a power conversion circuit unit using an IGBT as a semiconductor power conversion element arranged in one arm. It shows.

In FIG. 1, 1 is a gate G and a collector C
An IGBT with an emitter E, a freewheeling diode,
3 is a gate resistor, 4 is a pulse drive signal source, 5 is a clamping capacitor, 6 is a buffer diode, 7 is an auxiliary DC power supply, 8 is a backflow prevention diode, 9 ₁ is a positive power supply for a drive signal source, and 9 ₂ is a drive. A negative power supply for a signal source, and a circuit portion including a clamp capacitor 5, a buffer diode 6, an auxiliary DC power supply 7, and a backflow prevention diode 8 constitutes an active snubber.

In the IGBT 1, the collector C is connected to the positive electrode of a DC power supply (not shown in FIG. 1), the emitter E is connected to the negative electrode of the DC power supply, and the gate G is connected to one end of the gate resistor 3. Is done. The freewheel diode 2 has an anode connected to the emitter E and a cathode connected to the collector C
Connected to. The pulse drive signal source 4 has an output terminal connected to the other end of the gate resistor 3. Capacitor 5
Has one end connected to the cathode of the backflow prevention diode 8 and the other end connected to the gate G. The auxiliary DC power supply 7
The positive terminal is connected to the anode of the buffer diode 6, and the negative terminal is connected to the gate G. The buffer diode 6 has a cathode connected to one end of the clamping capacitor 5. The anode of the backflow prevention diode 8 is connected to the collector C. Positive supply 9 ₁ drive signal source,
The positive terminal is connected to the positive power terminal of the pulse drive signal source 4, and the negative terminal is connected to the emitter E. Negative power supply 9 ₂ drive signal source, the positive terminal is connected to the emitter E,
The negative terminal is connected to the negative power supply terminal of the pulse drive signal source 4.

FIGS. 2 (a) to 2 (d) are characteristic diagrams showing time-dependent variations in voltage and current or collector loss of each part of the IGBT 1 shown in FIG. 1. FIG. 2 (a) shows the gate voltage Vg. , (B) is the collector current Ic, (c) is the collector-emitter voltage Vce, and (d) is the collector loss.

2A to 2D, 31 is a characteristic curve of the gate voltage Vg, 32 is a characteristic curve of the collector current Ic, 33 is a characteristic curve of the collector-emitter voltage Vce, and 34 is a characteristic of the collector loss. It is a curve. Also, 3
Reference numerals 5, 36, 37, and 38 denote the characteristic curve of the gate voltage Vg, the characteristic curve of the collector current Ic, and the collector-emitter voltage V of the known IGBT 61, respectively, for comparison.
It is a characteristic curve of ce and a characteristic curve of collector loss. Note that the collector-emitter voltage Vce is normally held at the reference voltage, so in the following description, the collector-emitter voltage Vce is referred to as the collector voltage Vce.

The operation of the power conversion circuit according to the first embodiment having the above configuration will be described with reference to FIGS. When a drive signal of a positive pulse is output from the pulse drive signal source 4, the drive signal is transmitted through the gate resistor 3 to the IGBT.
1 is supplied to the gate G, and the IGBT 1 is turned on.

At this time, when the output of the pulse drive signal source 4 changes from a positive pulse to a negative pulse, and the negative pulse is supplied to the gate G of the IGBT 1 through the gate resistor 3, it is stored in the gate G of the IGBT 1. The positive charges that have been drawn out are extracted through the gate resistor 3, and the IGBT 1 is turned off. At the beginning of the turn-off operation of the IGBT 1, that is, when the collector voltage Vce is
During the period until the voltage (clamp operation start voltage) obtained by subtracting the forward voltage drop of the buffer diode 6 from the positive electrode voltage of (1), the voltage between the terminals of the clamping capacitor 5 is held at the clamp operation start voltage. Then, no current flows from the clamping capacitor 5 to the gate G of the IGBT 1. Thereafter, when the collector voltage Vce exceeds the clamp operation start voltage, a current corresponding to the voltage exceeding the clamp operation start voltage flows from the clamp capacitor 5 to the gate G, and the gate G is supplemented with positive charges. At this time, the gate voltage Vg changes slightly as shown in the lower characteristic curve 31 of FIG. 2A, and the change is shown in the upper characteristic curve 35 of FIG. 2A. This is almost the same as the change in the gate voltage Vg of the IGBT in the known power conversion circuit section. Then, the gate voltage Vg slightly increases, so that the collector voltage increase rate (dv / dt) of the IGBT 1 is suppressed, and the peak value of the collector voltage Vce is reduced. In this case, in the power conversion circuit unit of the first embodiment, as shown in the characteristic curve 33 of FIG. 2C, the known power conversion is performed until the collector voltage Vce exceeds the clamp operation start voltage. Since the collector voltage rise rate (dv / dt) is larger than the characteristic curve 37 in the circuit section, as shown in the characteristic curve 32 in FIG. In comparison, the time until the collector current Ic is cut off is shorter, and as shown by the characteristic curve 34 in FIG. 2D, the collector loss is smaller than the same characteristic curve 38 in the known power conversion circuit section. Can be greatly reduced.

FIG. 3 is a circuit diagram showing a second embodiment of the semiconductor power conversion device according to the present invention. The power conversion circuit uses an IGBT as a semiconductor power conversion element arranged in one arm. 3 shows an example of a unit.

In FIG. 3, reference numeral 10 denotes a current-reducing resistor, and other components that are the same as those shown in FIG. 1 are denoted by the same reference numerals.

The second embodiment differs from the first embodiment in that a current reducing resistor 1 is connected in series with a clamping capacitor 5.
0 is connected to limit the magnitude of the current flowing into the gate G of the IGBT 1, and the configuration other than that the current reducing resistor 10 is provided is the same as the configuration of the first embodiment.

According to the power conversion circuit of the second embodiment, the current flowing into the gate G is limited by the current reducing resistor 10, so that the rate of charging the gate G with positive charges is too high. It is possible to effectively prevent the gate voltage from being excessively accumulated due to the accumulation of a large amount of positive charges in the gate G and thereby destroying the gate G of the IGBT 1.

FIG. 4 is a circuit diagram showing a third embodiment of the semiconductor power conversion device according to the present invention.
1 shows an example of a power conversion circuit unit using an IGBT as a semiconductor power conversion element arranged in one arm.

In FIG. 4, reference numerals 11 ₁ and 11 ₂ denote voltage dividing resistors, and other components which are the same as those shown in FIG. 1 are denoted by the same reference numerals.

[0036] The third embodiment, with respect to the first embodiment, to connect the voltage dividing resistors 11 _1, 11 ₂ between the collector and emitter of IBGT1, the voltage dividing resistors 11 _1, 11 ₂ min The configuration in which the anode of the backflow preventing diode 8 is connected to the pressure point 11D, the voltage dividing resistors 11 ₁ and 11 ₂ are provided, and the anodes of the backflow preventing diode 8 are connected to the voltage dividing point 11D, This is the same as the first embodiment. These configurations and other configurations are the same as those of the first embodiment.

According to the power conversion circuit of the third embodiment, the voltage obtained at the voltage dividing point 11D is the collector voltage Vce
, The basic operation is the same as the operation of the first embodiment. That is, when the voltage at the voltage dividing point 11D exceeds the clamp operation start voltage, the collector voltage rise rate (dv)
/ Dt) flows into the gate G, and the IGB
The collector voltage rise rate (dv / dt) of T1 is suppressed,
The peak value of the collector voltage Vce is reduced. The current flowing into the gate G is limited by one of the voltage dividing resistors 11 _1.

In the third embodiment, the output voltage of the auxiliary DC power supply 7 can be reduced by dividing the collector voltage by the voltage dividing resistors 11 ₁ and 11 ₂ .

FIG. 5 is a circuit diagram showing a fourth embodiment of the semiconductor power conversion device according to the present invention, wherein a power conversion circuit unit using an IGBT as a semiconductor power conversion element arranged in one arm. This is an example.

In FIG. 5, reference numerals 11 ₁ and 11 ₂ denote voltage dividing resistors, and the same reference numerals are given to the same components as those shown in FIG.

The fourth embodiment differs from the third embodiment in that a gate current supply capacitor 12 is connected in parallel with _one of the voltage dividing resistors 111, and the gate current supply capacitor 12 Are the same as those of the third embodiment except for the connection.

[0042] In the fourth embodiment, while the current flowing into the gate G the third embodiment is the one of the voltage dividing resistors 11 ₁ has been restricted, providing a gate current supply capacitor 12 As a result, one of the voltage dividing resistors 11 ₁
, The gate current can be supplied, and the collector voltage rise rate (dv / dt) can be effectively controlled.

In the fourth embodiment, the collector voltage
The pressure is one of the voltage dividing resistors 11₁ And gate current supply capacitor
The combined impedance with the capacitor 12 and the other voltage dividing resistor
11 _Two The voltage at the voltage dividing point 11D
When the voltage exceeds the clamp operation start voltage, the collector voltage rises
Current corresponding to the rate (dv / dt) flows into the gate G
The rise rate (dv / dt) of the collector voltage of the IGBT1 is
Is suppressed, and the peak value of the collector voltage Vce is reduced.
You. In this case, one of the voltage dividing resistors 11₁ And gate current supply
The combined impedance with the capacitor 12
The smaller the voltage rise rate (dv / dt), the smaller the value.
Therefore, the collector voltage at which the clamp operation starts is lowered
Become so. Then, the collector voltage rise rate (dv / d
When t) is large, the collector voltage is lower than that of IGBT1.
Shorter time to exceed the withstand voltage limit between the collector and emitter
The collector voltage rise rate (dv / dt)
In order to keep the peak value of the high voltage low,
It is better to slightly advance the timing of supplying the current. sand
That is, when the collector voltage rise rate (dv / dt) is large.
It is preferable to lower the clamp operation start voltage.
On the other hand, when the collector voltage rise rate (dv / dt) is small
On the contrary, the collector voltage of the IGBT1
There is comparatively enough time to exceed the emitter breakdown voltage limit
Therefore, increasing the clamp operation start voltage
Thus, the collector loss can be reduced. This
As described above, the fourth embodiment has various excellent functions.
Conduct.

FIG. 6 is a circuit diagram showing a fifth embodiment of the semiconductor power converter according to the present invention.
1 shows an example of a power conversion circuit unit using an IGBT as a semiconductor power conversion element arranged in one arm.

In FIG. 6, the same components as those shown in FIG. 5 are denoted by the same reference numerals.

The fifth embodiment differs from the fourth embodiment in that _one of the voltage dividing resistors 111 is omitted.
The configuration other than omitting _one voltage dividing resistor 111 is the same as the configuration of the fourth embodiment.

In the fifth embodiment, when the rate of rise of the collector voltage (dv / dt) is small, the voltage at the voltage dividing point 11D becomes extremely low. 7 without exceeding the positive voltage
Although the effect of clamping the collector voltage against the overvoltage state of the collector voltage cannot be expected, when the rate of rise of the collector voltage (dv / dt) is large, the impedance value of the capacitor 12 for supplying the gate current becomes small, so that the voltage dividing point 11D Becomes higher, and a clamping effect against an overvoltage state of the collector voltage can be expected.

The fifth embodiment, since one of the voltage dividing resistors 11 ₁ used in the fourth embodiment is not necessary, is possible to reduce the number of components in comparison with the fourth embodiment it can. In the fifth embodiment, the dependence of the collector voltage rise rate (dv / dt) on the clamp operation start voltage is large. Only when the turn-off collector voltage rise rate (dv / dt) is large, the overvoltage The present invention is suitable for use in a semiconductor power converter that needs to clamp the collector voltage in a state.

FIG. 7 is a circuit diagram showing a sixth embodiment of the semiconductor power conversion device according to the present invention. The power conversion circuit uses an IGBT as a semiconductor power conversion element arranged in one arm. 3 shows an example of a unit.

In FIG. 7, the same components as those shown in FIG. 4 are denoted by the same reference numerals.

[0051] The sixth embodiment, compared third embodiment omits the auxiliary DC power source 7, which was connected to the anode of the buffer diode 6 to the positive terminal of the driving signal source for the positive electrode power source 9 ₁ , i.e. the auxiliary instead of the DC power supply 7 are those utilizing a positive electrode power source 9 ₁ drive signal source, eliminating the auxiliary DC power source 7, the positive electrode side anode a driving signal source for the positive electrode power source 9 _first buffer diode 6 The configuration other than the connection to the terminal is the same as the configuration of the third embodiment. The operation of the sixth embodiment is essentially the same as the operation of the third embodiment.

[0052] The sixth embodiment, the use of the positive electrode power supply 9 ₁ for existing driving signal source, there is no need to provide a new auxiliary DC power source 7, to reduce the number of parts, semiconductor power conversion device Can be made compact.

FIG. 8 is a circuit diagram showing a seventh embodiment of the semiconductor power converter according to the present invention.
1 shows an example of a power conversion circuit unit using an IGBT as a semiconductor power conversion element arranged in one arm.

In FIG. 8, the same components as those shown in FIG. 5 are denoted by the same reference numerals.

[0055] The seventh embodiment is, with respect to the fourth embodiment, omit the auxiliary DC power source 7, which was connected to the anode of the buffer diode 6 to the positive terminal of the driving signal source for the positive electrode power source 9 ₁ , i.e. the auxiliary instead of the DC power supply 7 are those utilizing a positive electrode power source 9 ₁ drive signal source, eliminating the auxiliary DC power source 7, the positive electrode side anode a driving signal source for the positive electrode power source 9 _first buffer diode 6 The configuration other than the connection to the terminal is the same as the configuration of the fourth embodiment. The operation of the seventh embodiment is essentially the same as the operation of the fourth embodiment.

[0056] The seventh embodiment, the use of the positive electrode power supply 9 ₁ for existing driving signal source, there is no need to provide a new auxiliary DC power source 7, to reduce the number of parts, semiconductor power conversion device Can be made compact.

FIG. 9 is a circuit diagram showing an eighth embodiment of a semiconductor power conversion device according to the present invention, wherein a power conversion circuit unit using an IGBT as a semiconductor power conversion element arranged in one arm. This is an example.

In FIG. 9, the same components as those shown in FIG. 6 are denoted by the same reference numerals.

[0059] The eighth embodiment, with respect to the fifth embodiment, omit the auxiliary DC power source 7, which was connected to the anode of the buffer diode 6 to the positive terminal of the driving signal source for the positive electrode power source 9 ₁ even in this case, which utilizes a positive electrode power source 9 ₁ driving signal source in place of the auxiliary DC power source 7, eliminating the auxiliary DC power source 7, the anode of the driving signal source for the positive electrode power source 9 _first buffer diode 6 The configuration other than the connection to the positive terminal on the positive side is the same as the configuration of the fifth embodiment. The operation of the eighth embodiment is also essentially the same as the operation of the fifth embodiment.

[0060] the eighth embodiment, the use of the positive electrode power supply 9 ₁ for existing driving signal source, there is no need to provide a new auxiliary DC power source 7, to reduce the number of parts, semiconductor power conversion device Can be made compact.

FIG. 10 is a circuit diagram showing a ninth embodiment of the semiconductor power converter according to the present invention.
This shows an example of a power conversion circuit unit using an IGBT as a semiconductor power conversion element arranged in one arm, in which two power conversion circuit units are connected in series.

In FIG. 10, 1 'is an IGBT having a gate G, a collector C and an emitter E, 2' is a freewheeling diode, 3 'is a gate resistor, 4' is a pulse drive signal source,
5 'clamp capacitor, 6' buffer diode, 8 'backflow preventing diode, 9 _1' is a positive electrode power drive signal source, 9 ₂ 'is negative power drive signal source, 11 _2'
Is the other voltage-dividing resistor, 12 'is a gate current supply capacitor, and other components that are the same as those shown in FIG. 9 are given the same reference numerals.

An IGBT 1 'having a gate G, a collector C and an emitter E, a freewheeling diode 2', a gate resistor 3 ', a pulse drive signal source 4', a clamping capacitor 5 ', a buffer diode 6', and a backflow prevention The diodes 8 ′ and 9 ₁ ′ are a power conversion circuit unit including a drive signal source positive power supply 9 ₁ ′, a drive signal source negative power supply 9 ₂ ′, the other voltage dividing resistor 11 ₂ ′, and a gate current supply capacitor 12 ′. Is the same as the connection configuration of the opposing components of the power conversion circuit unit shown in FIG.

In the ninth embodiment, while the eighth embodiment is constituted by one power conversion circuit section, the ninth embodiment is constituted by two power conversion circuit sections of the same configuration connected in series. Is what it is.

Generally, when two or more IGBTs having a difference in element characteristics such as gate capacitance are used in series, the turn-off timing of the IGBT having a small gate capacitance is earlier than that of the IGBT having a smaller gate capacitance. The turn-off timing of the IGBT 1 having the gate capacitance is delayed, and as a result, the IGBT having the small gate capacitance bears the DC voltage of the IGBT having the large gate capacitance, as compared with the turn-off when only one IGBT is used. In some cases, the collector voltage may rise sharply, and an IGBT having a small gate capacitance may be destroyed by application of a high collector voltage.

Incidentally, the ninth embodiment is different from the IG
When the collector voltages of the BTs ₁ and ₁ 'exceed the output voltages of the drive signal source positive power supplies 9 ₁ and 9 ₁ ', currents are supplied to the gates G via the clamp capacitors 5 and 5 ', respectively. , 1 ′, the rate of rise of each collector voltage (dv / dt) becomes gentle, and the collector voltage can be prevented from becoming high. Since the high collector voltage applied to each collector C of each of the IGBTs 1 and 1 'connected in series is individually suppressed,
It is possible to equalize the burden of the collector voltages of 1, 1 '.

In this case, the configuration of the power conversion circuit units connected in series is not limited to the configuration according to the eighth embodiment, but may be the configuration according to the first to seventh embodiments. The high collector voltage applied to the collector C of each of the IGBTs 1 and 1 'connected in series is individually suppressed, and the burden of the collector voltage of each IGBT 1 and 1' is equalized.

In the above embodiments, an example in which the semiconductor power conversion element is an IGBT has been described.
The semiconductor power conversion element used in the present invention is not limited to an IGBT, but may be another semiconductor power conversion element similar to an IGBT, for example, a power MOSFET having a MOS gate.
Even with T, the same function can be achieved.

[0069]

As described above, according to the present invention, the IGB
A capacitor is connected between the collector and gate of T or between the collector voltage dividing point and the gate, and a series circuit of an auxiliary DC power supply or a drive signal source power supply and a buffer diode is connected in parallel with this capacitor. Since the voltage across the terminals does not drop below a certain voltage, and the voltage on the collector side of the capacitor cannot exceed the voltage on the high side of the DC power supply, the collector current after the turn-off of the IGBT starts. There is an effect that the time until the decrease can be shortened, whereby the collector loss of the IGBT can be reduced.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing a first embodiment of a semiconductor power conversion device according to the present invention.

FIG. 2 is a characteristic diagram illustrating a temporal variation of a voltage and a current or a collector loss of each part of the IGBT illustrated in FIG. 1;

FIG. 3 is a circuit diagram showing a second embodiment of the semiconductor power converter according to the present invention.

FIG. 4 is a circuit diagram showing a third embodiment of the semiconductor power conversion device according to the present invention.

FIG. 5 is a circuit diagram showing a fourth embodiment of the semiconductor power conversion device according to the present invention.

FIG. 6 is a circuit diagram showing a fifth embodiment of the semiconductor power conversion device according to the present invention.

FIG. 7 is a circuit diagram showing a sixth embodiment of the semiconductor power converter according to the present invention.

FIG. 8 is a circuit diagram showing a seventh embodiment of the semiconductor power conversion device according to the present invention.

FIG. 9 is a circuit diagram showing an eighth embodiment of the semiconductor power converter according to the present invention.

FIG. 10 is a circuit diagram showing a ninth embodiment of a semiconductor power conversion device according to the present invention.

FIG. 11 is a circuit diagram showing an example of a configuration of a main part of a known semiconductor power conversion device.

FIG. 12 is a circuit diagram showing a configuration of a power conversion circuit unit of one arm when an IGBT is used as a semiconductor power conversion element arranged in each arm of a known semiconductor power conversion device.

[Explanation of symbols]

1, 1 'IGBT 2, 2' freewheeling diode 3, 3 'gate resistance 4, 4' pulse drive signal source 5, 5 'clamping diode 6, 6' buffer diode 7 auxiliary DC power supply 8, 8 'backflow preventing diode 9 ₁ , 9 ₁ ′ Positive power supply for drive signal source 9 ₂ , 9 ₂ ′ Negative power supply for drive signal source 10 Down current resistance 11 ₁ , 11 ₂ , 11 ₂ ′ Voltage dividing resistance 12, 12 ′ Gate current supply capacitor

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Ryuji Iyoya 7-1-1, Omikacho, Hitachi City, Ibaraki Prefecture Inside the Hitachi Research Laboratory, Hitachi, Ltd. (72) Inventor Hiromitsu Sakai 1-chome, Kokubuncho, Hitachi City, Ibaraki Prefecture No. 1-1 F-term in Hitachi Kokubu Office (reference) 5H740 BA11 BB01 BC01 BC02 HH06 JA01 JB02 MM03

Claims (11)

[Claims] 1. An IGBT in which an arm connecting a DC power supply and a load is arranged in each arm, wherein the IGBT has a collector and an emitter connected in series to the arm.
A capacitor connected between the collector and the gate of the capacitor and supplying a current corresponding to the collector-emitter voltage change rate to the gate; and an auxiliary DC power supply connected in parallel to the capacitor through a buffer diode. Wherein when a voltage obtained by adding a forward voltage drop of the buffer diode to the collector side voltage exceeds an output voltage of the auxiliary DC power supply, a current is supplied to the gate through the capacitor. . 2. A resistor is connected in series with the capacitor,
The semiconductor power converter according to claim 1, wherein a current supplied to the gate is limited by the resistor. 3. A power conversion element arranged in each arm connecting a DC power supply and a load, wherein the IGBT has a collector and an emitter connected in series to the arm and an IGBT connected between the collector and the emitter. A voltage divider, a capacitor connected between the voltage dividing point of the voltage divider and the gate of the IGBT, for supplying a current corresponding to the collector-emitter voltage change rate to the gate, and a capacitor connected in parallel to the capacitor through a buffer diode. An auxiliary DC power supply,
When a voltage obtained by adding the forward voltage drop of the buffer diode to the voltage at the voltage dividing point side of the capacitor exceeds the output voltage of the auxiliary DC power supply, a current is supplied to the gate through the capacitor. Semiconductor power converter. 4. A power conversion element disposed in each arm connecting a DC power supply and a load, wherein an IGBT having a collector and an emitter connected in series to the arm and an IGBT connected between the collector and the emitter are provided. A voltage divider, a capacitor connected between the voltage dividing point of the voltage divider and the gate of the IGBT, for supplying a current corresponding to the collector-emitter voltage change rate to the gate, and a capacitor connected in parallel to the capacitor through a buffer diode. When the voltage obtained by adding the forward voltage drop of the buffer diode to the voltage at the voltage dividing point of the capacitor exceeds the output voltage of the DC power supply for the gate drive circuit,
A semiconductor power converter, wherein a current is supplied to the gate through the capacitor. 5. The semiconductor power converter according to claim 3, wherein the voltage divider includes two voltage-dividing resistors connected in series. 6. The semiconductor power converter according to claim 5, wherein a capacitor is connected in parallel to one of the two voltage dividing resistors. 7. The voltage divider according to claim 3, wherein the voltage divider comprises a voltage dividing resistor and a voltage dividing capacitor connected in series.
Or the semiconductor power converter according to 4. 8. The buffer diode according to claim 1, wherein the collector-side voltage or the voltage-dividing-point-side voltage of the capacitor reaches the output voltage of the auxiliary DC power supply or the DC power supply for the gate drive circuit. The semiconductor power converter according to any one of claims 1, 3, and 4, wherein the semiconductor power converter is connected to a polarity that does not prevent a voltage increase of the voltage at the voltage point side. 9. The semiconductor power conversion device according to claim 4, wherein the DC power supply for the gate drive circuit is a power supply for a gate drive circuit that turns on and off a gate voltage of the IGBT. 10. The IGBT according to claim 1, wherein two IGBTs are connected in series to one arm.
The semiconductor power converter according to any one of the above. 11. The semiconductor power conversion device according to claim 1, wherein said power conversion element is formed of a MOS element other than an IGBT.