JPH05268771A - Self-arc extinguishing semiconductor power converter - Google Patents

Abstract

PURPOSE:To obtain a self-arc extinguishing semiconductor power converter for producing an output voltage having continuously variable waveform while suppressing ripple in current waveform by connecting two set of series multiplex self-arc extinguishing power converters in parallel, at the output terminals thereof, through a center tap reactor. CONSTITUTION:Upon turn ON of self-extinguishing elements 6a, 7a and 6b, 7b, output voltage of a center tap reactor 15 goes 0V. Similarly upon turn ON of self-arc extinguishing elements 5a, 6a and 6b, 7b, output voltage of the reactor 15 has a level of +E/2 and upon turn ON of self-arc extinguishing elements 5a, 6a and 5b, 6b, the output voltage has a level +E. Since output voltage of five levels can be obtained in step through combination of turn ON modes, PWM frequency can be halved for same ripple of output current. According to the constitution, switching loss is reduced, efficiency of power converter is enhanced, influence of unstable output voltage caused by turn OFF time of self-arc extinguishing element is suppressed, and control accuracy of output voltage is enhanced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power converter using a self-arc-extinguishing semiconductor element, which requires a small number of switching operations
The present invention relates to a circuit that obtains a good output current waveform.

[0002]

2. Description of the Related Art FIG. 4,203,15
1 shows an example of the proposed circuit. In this power converter, forward converters 1 and 2 for converting alternating current into direct current, capacitors 3 and 4 for obtaining a voltage source, and two self-arc-extinguishing type semiconductor devices 5, 6 and 7, 8 are connected in series, respectively. Diode elements 9, 10 and 1 respectively connected in anti-parallel to semiconductor elements
It is composed of 1 and 12. Furthermore, diodes 13 and 14 connected in anti-parallel are added between the connection points of the voltage source capacitors 3 and 4 and the respective midpoints of the self-extinguishing semiconductor elements 5, 6 and 7, 8 connected in series. Has been done.
FIG. 7 shows an example of the operation of the switching elements 5, 6, 7, and 8, and FIG. 8 shows the operation waveform of this self-turn-off semiconductor converter. Assuming that the virtual neutral point is the zero point in FIG. 5, when the output voltage is zero, the neutral point potential 0 through the diode 13 and the self-extinguishing element 6 or the diode 14 and the self-extinguishing element 7.
Fix the voltage at the point. When the output voltage is + E, the self-extinguishing elements 5 and 6 are switched on. The output voltage is -E
In that case, the self-extinguishing elements 7 and 8 are switched on.
When switching in this way, the output voltage is 0, +
It changes to E and -E, and it becomes possible to achieve 3 levels.

This three-level inverter is a so-called serial multiplex system, but considering that the output voltage can be continuously varied, as shown in FIG. It cannot be shortened and the output voltage cannot be continuously changed from 0V. Considering the case where the output frequency is low, the self-arc-extinguishing element 6 needs to be turned on for a half cycle of the output frequency. Therefore, in a semiconductor element having current concentration and a short thermal time constant, the output capacitance is Need to be reduced. Since the output current is desirably a sine wave corresponding to the output frequency, the self-extinguishing element is pulse-width modulated, but the pulse-width modulation frequency needs to be increased to reduce the current ripple of the output current. When the pulse width modulation frequency is increased, the switching loss of the self-extinguishing element increases,
Reduce system efficiency.

On the other hand, a parallel multiplex system shown in FIG. 6 has been proposed as a system for continuously varying the output voltage to prevent current concentration in the self-turn-off device. With this method,
Since the output voltage of 0 V can be achieved by switching on the self-extinguishing elements 3a and 4b or 4a and 3b as shown by a circle in FIG. 9, the control is independent of the turn-off time of the self-extinguishing element. it can. The output voltage 0V is 2
Since it can be achieved in one mode, current concentration can be prevented by switching the switching state.

[0005]

However, in order to reduce the ripple component of the output current even in the parallel multiplex system, it is necessary to raise the pulse width modulation frequency.

The object of the present invention is to reduce the ripple component of the output current in the quadrature power converter and the current on the AC power supply side in the AC / DC power converter without increasing the pulse width modulation frequency in the serial multiplex system. An object of the present invention is to provide a power converter device using a self-extinguishing semiconductor element that can be used.

[0007]

In order to achieve the above object, a midpoint of the arm of a power converter and a midpoint of a capacitor for a voltage source, which are composed of arms in which even-numbered self-arc-extinguishing semiconductor elements are connected in series, are provided. 2 sets of orthogonal power converters each including a diode connected in antiparallel with the self-extinguishing semiconductor element, and a center tap type reactor in which output terminals of the two sets of orthogonal power converters are connected in parallel. This is the self-extinguishing semiconductor power conversion device.

As the AC / DC power converter, a self-extinguishing semiconductor power converter having the same structure as described above may be used. Further, the AC / DC power converter and the orthogonal power converter may be used in combination.

[0009].

With this structure, the above object can be achieved by the following operation according to the present invention. In the power converter, the self-extinguishing type semiconductor device and the diode in the antiparallel connection are provided between the arm midpoint and the voltage source midpoint of the capacitor to provide 0 V and the voltage + E of the voltage source capacitor and −.
You get 3 levels of E. Here, when the output terminals of the two sets of power converters of this configuration are connected to the terminals at both ends of the center tap type reactor, an intermediate value of the terminal voltage at both ends is obtained from the center tap of the center tap type reactor. Therefore, by combining the first set of power converter output voltage and the second set of output voltage, 0, +1/2
It is clear that E, E, -1 / 2E can be obtained, and that 0 can also be obtained by canceling each other by + voltage and -voltage. In this way, although each is a three-level power converter, it can be made into a five-level power converter by using the center tap type reactor.

[0010] Here, since the voltage becomes 5 levels, the voltage applied during switching of the self-arc-extinguishing type semiconductor element becomes 1 / 2E, and the ripple component of the output current waveform is 1/2 if the pulse width modulation frequency is the same. Therefore, if the ripple components are the same, the pulse width modulation frequency may be 1/2.

[0011]

FIG. 1 shows an embodiment of the present invention. The same elements as those in FIG. 5 which compose FIG. 1 are denoted by subscripts a and b. This figure is composed of a self-extinguishing type power converter device I and II disclosed in the prior art and a center tap type reactor 15 for connecting the output terminals of the device in parallel.

With this configuration, the switch mode of the inverter for setting the output voltage to 0V is as follows.

(1) In the serial multiple mode, the self-extinguishing elements 6a, 7a and 6b, 7b are turned on.

(2) In the parallel multiplex mode, the self-extinguishing elements 5a, 6a and 7b, 8b are turned on. The output voltage of the center tap type reactor is {(+ E) + (-E)} /
Since it becomes 2, it becomes 0V.

(3) Next, similar to (2), the self-extinguishing elements 7a, 8
Even when a, 5b, and 6b are turned on, the output voltage becomes 0V.

By combining these modes, the output voltage can be continuously varied from 0 V as shown in the switching mode of the self-extinguishing element of FIG. 2, and the self-extinguishing elements 6a, 7a at the time of low frequency output and It is possible to prevent current concentration on 6b and 7b.

Further, as shown in the output voltage waveform of FIG. 3, the output voltage can be changed stepwise in five levels.

In the case of mode M2 in FIG. 3, the self-extinguishing element 5
When a, 6a and 6b, 7b are turned on, the output voltage of the center tap type reactor 15 is {(+ E) + (0)}.
/ 2 = + E / 2. In mode M3, when 5a, 6a and 5b, 6b are turned on, the output voltage is {(+ E) +
(+ E)} / 2 = + E. 6a for mode M6,
When 7a, 7b, and 8b are turned on, {(0) + (-
E)} / 2 = -E / 2. 7 for mode M7
When a, 8a and 7b, 8b are turned on, {(-E) +
(-E)} / 2 = -E.

Since the output voltage can be stepwise in 5 levels in this way, in the case of 3 levels, the ripple of the output current is as shown in equation (1) when the load inductance is L.

[0020]

[Equation 1]

In the case of 5 levels, the ripple of the output current is
It becomes like the formula (2).

[0022]

[Equation 2]

In the case of 3 levels, the time is as shown in equation (3).

[0024]

[Equation 3]

On the other hand, in the case of 5 levels, if the ripple of the output current is the same, the range of the equation (4) is allowed, and the pulse width modulation frequency can be halved.

[0026]

[Equation 4]

Since the self-extinguishing element causes a turn-on loss and a turn-off loss during switching, reducing the number of times of switching reduces the loss, and as a result, improves the system efficiency.

The self-extinguishing element requires a certain time to turn off, but the output voltage becomes indefinite during this period. Therefore, when the load is an electric motor, the power becomes discontinuous and causes torque ripple or the like. Reducing the pulse width modulation frequency reduces the output voltage indefiniteness and reduces its effect. Therefore, it is sufficient to reduce the pulse width modulation frequency with a 5-level inverter.

When used as a converter in this configuration, the ripple component of the current on the AC power supply side is reduced as in the case of the inverter. Further, by using the converter and the inverter of the present configuration in combination, it is possible to make the current having a small ripple component of the current waveform both in the AC power supply on the input side and the load on the output side. Although the above-described one embodiment is shown as a single phase, it can be applied to a multi-phase.

[0030]

Since the number of times of switching of the self-extinguishing element can be reduced without increasing the output current ripple,
Switching losses are reduced, resulting in improved power converter device efficiency.

Further, by reducing the number of times of switching, it is possible to reduce the uncertain influence of the output voltage due to the turn-off time of the self-extinguishing element, and to improve the control accuracy of the output voltage.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration of an exemplary embodiment of the present invention.

FIG. 2 is a diagram showing an example of a switching mode of a self-extinguishing element according to an embodiment.

FIG. 3 is a diagram showing an output voltage waveform according to an embodiment.

FIG. 4 is a diagram showing the configuration of another embodiment of the present invention.

FIG. 5 is a diagram illustrating a conventional configuration example of a serial multiplex type three-level inverse converter.

FIG. 6 is a diagram showing a conventional configuration example of a parallel multiplex type three-level inverse converter.

FIG. 7 is a diagram showing an example of a switching mode of a conventional series self-extinguishing element of a three-level inverse converter.

FIG. 8 is a diagram showing an output voltage waveform of a conventional example of a three-level inverse converter.

FIG. 9 is a diagram showing an example of a switching mode of a parallel multiplexing type conventional self-extinguishing element of a three-level inverse converter.

FIG. 10 is a diagram showing a comparison between the serial multiplexing method and the parallel multiplexing method.

[Explanation of symbols]

1, 2, 1c, 2c AC / DC power converters 1a, 2a, 1b, 2b, AC / DC power converters 3, 4, 3c, 4c Power capacitors 3a, 4a, 3b, 4b Power capacitors 5, 6, 7, 8, 5e , 6e, 7e, 8e self-extinguishing semiconductor elements 5a, 6a, 7a, 8a, 5b, 6b, 7b, 8b self-extinguishing semiconductor elements 5c, 6c, 7c, 8c, 5d, 6d, 7d, 8d self-extinguishing Arc-shaped semiconductor elements 9, 10, 11, 12, 13, 14 Diodes 9a, 10a, 11a, 12a, 13a, 14a Diodes 9b, 10b, 11b, 12b, 13b, 14b Diodes 9c, 10c, 11c, 12c, 13c, 14c diode 9d, 10d, 11d, 12d, 13d, 14d diode 9e, 10e, 11e, 12e diode 15 center tap type reactor 16 load 17 interconnection reactor 18 AC power supply

Claims (3)

[Claims] 1. A self-extinguishing semiconductor device is provided between the midpoint of the arm and the midpoint of a capacitor for a voltage source of a power converter including an arm in which an even number of self-extinguishing semiconductor devices are connected in series. A self-extinguishing semiconductor power conversion device comprising: two sets of orthogonal power conversion devices each including a diode connected in parallel; and a center tap type reactor in which output terminals of the two sets of orthogonal power conversion devices are connected in parallel. 2. A self-extinguishing semiconductor device is provided between a midpoint of the arm and a midpoint of a capacitor for a voltage source of a power converter including an arm in which an even number of self-extinguishing semiconductor devices are connected in series. A self-extinguishing semiconductor power conversion device comprising: two sets of orthogonal power conversion devices each including a diode connected in parallel; and a center-tap reactor in which input terminals of the two sets of orthogonal power conversion devices are connected in parallel. 3. A self-extinguishing semiconductor device is provided between the midpoint of the arm and the midpoint of a capacitor for a voltage source of a power converter including an arm in which an even number of self-extinguishing semiconductor devices are connected in series. A self-extinguishing semiconductor power converter comprising two sets of orthogonal power converters each including a diode connected in parallel, and a center tap type reactor having input terminals of the two sets of orthogonal power converters connected in parallel, The voltage source capacitor is used as a DC voltage source, and the self-extinction is provided between the arm midpoint and the voltage source capacitor midpoint of a power converter including an arm in which an even number of self-extinguishing semiconductor elements are connected in series. Two sets of orthogonal power conversion devices each including an arc-shaped semiconductor element and a diode connected in antiparallel and a center tap type reactor to which output terminals of the two sets of orthogonal power conversion devices are connected in parallel are provided. Self-extinguishing semiconductor power converter.