JPS5976167A - Number-of-phase converter - Google Patents

Abstract

PURPOSE:To suppress the unbalance of a voltage of a load connected to a number-of-phase converter by providing a middle terminal having different winding distribution at the main winding of the converter and selectively connecting the output winding of a transformer to the main winding in response to the capacity of the load. CONSTITUTION:A number-of-phase converter 21 has a U-V terminal, a main winding 21a including the middle terminal of U1-V1 and an auxiliary winding 21b including a Z-W terminal. The terminals U, V, U1, V1 ofthe winding 21a are respectively connected to the output winding and hence the tertiary winding 14 of a transformer 10 through changeover switches 22A-22D. When the capacity of a load is less, the switches 22C, 22B are closed to connect the terminals U1, V of the winding 21a to the tertiary winding 14 of the transformer 10. When the capacity of the load is large, the switches 22A, 22D are closed to connect the terminals U, V1 of the winding 21a to the tertiary winding 14 of the transformer 10. When the capacity of the load is middle, the switches 22A, 22B are closed to connect the terminals U, V of the winding 21a to the tertiary winding 14 of the transformer 10.

Description

[Detailed Description of the Invention] (,) Description of the Technical Field The present invention relates to an improvement of a rotating electric machine type phase number conversion device that converts single-phase alternating current to three-phase alternating current, and particularly relates to a technique for balancing the output voltage of each phase. Regarding.

(b) Description of Prior Art In AC electric cars, in addition to the main motor for driving the electric car, several low-voltage auxiliary motors are used, such as a blower motor for cooling the main motor, a motor for cooling oil of the transformer, and a blower motor for resistors. are using. However, since the overhead line power source is single-phase AC, if a single-phase induction motor is used as the low-voltage auxiliary motor, the starting capacitor, contactor, etc. will be required individually, and the weight and installation dimensions will increase. A parallel-phase induction motor, which is inexpensive and easy to maintain, is used, and the power source is exclusively a three-phase power source that is converted from a single-phase AC overhead line power source using a rotating electrical machine-type phase converter. There is.

FIG. 1 shows a circuit of a conventional phase number converter.

In FIG. 1, 10 is a transformer, which has a primary winding 12 and a secondary winding 13, which receive power from a pantograph 11 that is connected to an overhead wire.
It has a tertiary winding 14 output winding. The secondary winding 13 is connected via a rectifier 15 to a main DC motor (not shown) for driving the vehicle. The tertiary winding 14 has a center tap and supplies power to the phase number converter 16.

The phase number converter 16 is started as a single-phase induction motor using a resistance split phase starting method. That is, it has a main winding 16a and an auxiliary winding 16b, and a starting resistor 17 is inserted in series with the auxiliary winding 16b via a contactor 18.

A rotating magnetic field is created by shifting the phase of the magnetic flux created by the wire 16a and the magnetic flux created by the auxiliary winding 16b, generating a starting rotational force for starting, and after the rotational speed increases, the starting resistor 17 is separated by the contactor 18, and the load is contacted. 19 to supply three-phase alternating current to a load group 20 such as the three-phase induction motor described above.

Since the phase number converter 16 outputs a three-phase AC voltage by a combination of two windings, the main winding 16a and the auxiliary winding 16b, the overhead line voltage, that is, the input from the tertiary winding 14 of the transformer 10 Due to voltage fluctuations and load fluctuations, the three-phase output voltage becomes an unbalanced voltage instead of a balanced voltage. That is, as shown in the vector diagram of the output voltage of the phase number converter shown in FIG. It is larger than the vector Z-W.

Also, the phase difference between the UV phase of the main winding 16a and the voltage vector UV is large.
The voltage vector Z-W of the main winding 16a is smaller than the voltage vector Z-W0 in the balanced state, and
The phase difference between the phase voltage vectors U- and V is also large and small.

FIG. 3 shows the output voltage unbalance rate of the phase number converter 16 when the input voltage and load of the phase number converter 16 are changed. The voltage unbalance rate is determined by the JEC114 (synchronous machine) standard (ratio of positive-sequence voltage (+?, I) and negative-sequence voltage (+?, l) (1*2
1/l VII x 100%), and the larger the unbalance factor, the larger the negative sequence voltage. Fourth
6 to 6 show the output voltage unbalance rate of the phase number converter 16 (the output voltage of each phase for two, each phase current, and the induction motor The relationship between the temperature rise of each phase winding is shown in a curve diagram.

In other words, in the past, due to the negative phase current due to the unbalanced voltage mentioned above, it was necessary to take into consideration the increase in temperature rise in the induction motor windings, and to use an induction motor that had more margin for temperature rise than when used with balanced voltage. On the 1st floor, there was a gap, a gap, and a gap.

(C) Purpose of the Invention The present invention has been made in view of the above points, and includes providing an intermediate terminal with a different winding distribution in the main winding of a phase number converter, and connecting the output winding of the transformer with the main winding. The present invention provides a phase number converter that selectively connects the terminals according to the load capacity and suppresses voltage unbalance of a load connected to the phase number converter.

(dl Structure of the Invention The structure of the present invention will be explained below with reference to the drawings. Fig. 7 is a main circuit diagram showing an embodiment of the phase number converter of the present invention. vessel 10
a primary winding 12 and a tertiary winding 14, a starting resistor 17,
The starting contactor 18 has the same configuration as the conventional one, and the phase number converter 21
comprises a main winding 21a having a UV terminal and an intermediate terminal Ul p VI, and an auxiliary winding 21b having a Z-W terminal, each terminal U, V of the main winding 21a.

Ma IV is a changeover switch 22A that uses a static switch constructed of a thyristor or the like or an electromagnetic contactor.

It is connected to the output or tertiary winding 14 of the transformer 10 via 22B, 22C, and 22D.

With the above circuit configuration, when the capacity of the load (not shown) is small, the changeover switches 22C and 22B are closed and the terminals U and 2 of the main winding 21a are connected to the tertiary winding 14 of the transformer 10 ; If the load capacity is large, close switching switches Y-22A and 22D and connect terminals U and ■ of the main winding 21a to the tertiary winding 14 (-) of the transformer 10, and If there is a problem other than the above, the changeover switches 22A and 22B are closed to connect the terminals U and vI of the main winding 21a to the tertiary winding 14 of the transformer 10.

(e) Operation of the invention The operation of the phase number converter of the invention shown in FIG. 7 will be explained below with reference to the drawings.

FIGS. 8(a) and 8(b) are vector diagrams of the output voltage of the phase number converter shown in FIG. , ゛ and the voltage vector 7, -W in the case of a balanced state of the voltage vector Z-W at the time of load, although neither the magnitude nor the phase difference is different from the conventional one, E. The voltage generated varies in magnitude depending on the terminal used.

Figure 8 (,) shows the selector switches 22C and 2 in Figure 7.
This is a voltage vector diagram when the capacity of the load with 2B closed is small, and the voltage vector created by the main graduation line 21a is the same as that of the conventional U-V
However, the voltages between the phases are more balanced than in the past. In addition, Fig. 8 (1,) shows the changeover switch 22.
This is a voltage vector diagram when the load capacity is large with A and 22D closed, and the voltage vector created by the main winding 21a is U-V compared to the conventional U-V as described above, and the voltage between each is the same as before. In comparison, equilibrium state 2 is reached.

Figure 9 is a voltage unbalance rate characteristic diagram showing the above relationship between the load capacity and the output voltage unbalance rate.
With the circuit configuration shown in the figure, selector switches 22A and 22B
In the conventional case where the changeover switches 22C and 2213 are closed in the circuit configuration shown in FIG. Each is a voltage unbalance rate characteristic.

In other words, curve (,) is used in the range A shown in Figure 9 where the load capacity is small, curve (b) is used in the range B where the load capacity is large, and curve (c) is used in the range C where the shellfish capacity is large. .

As a result, the voltage unbalance between each phase for each load capacity can be improved.

(f) As described in detail, according to the phase number conversion device of the present invention, the phase also changes (
For conversion, intermediate terminals with different winding distributions are provided on the main windings, and the terminals of these main windings are selected depending on the load capacity and connected to the output winding of the transformer. This makes it possible to improve voltage unbalance between each phase, thereby reducing heat generation caused by unbalanced voltage in equipment on the load side.
The load side equipment can be made smaller and lighter.

[Brief explanation of the drawing]

Figure 1 is a diagram of a conventional phase number conversion circuit, Figures 2 and 3 are diagrams showing the characteristics of Figure @1, Figures 4 to 6 are explanatory diagrams of characteristics, and Figure 7 is a diagram of the present invention. The figures showing the embodiment, FIGS. 8 and 9, are diagrams for explaining the characteristics of FIG. 7. 10...Transformer 14...Transformer output winding 16.21...Phase number converter 16a, 21a...Main winding 16b, 21b...Auxiliary winding 22A, 2:2B, 22C , 22D...Choice switch Fig. 1 0 Fig. 2 W. Fig. 3. Each t (kVA) of Yugu Fig. 4. Room pressure complaint #f year (2) Fig. 7 Fig. 8 (1; L) Fig. 8 3. )

Claims (1)

[Claims] A phase number converter having a main winding and an auxiliary winding provided with at least two or more terminals with different winding distributions, and the terminals being selectively connected to the output winding of the transformer depending on the total amount of load. A phase number conversion device characterized by being equipped with a changeover switch.