JPH0755052B2 - Phase converter - Google Patents

Description

The present invention relates to a phase number converter, and more particularly to a rotary electric machine type phase number converter for converting a single-phase alternating current into a three-phase alternating current.

[Conventional technology]

AC electric vehicles use several low-voltage auxiliary electric motors such as a fan motor for cooling the main motor, a motor for cooling oil for transformers, and a fan motor for resistors, in addition to the main motor for driving the electric car.
However, since the overhead line voltage is a single-phase alternating current, a phase number converter that obtains three phases from a single phase is required in order to make the above-mentioned motor a three-phase induction motor that is easy to maintain.

As described in Japanese Patent Laid-Open No. 59-25582, a conventional device is provided with a plurality of intermediate terminals in a tertiary winding in order to reduce a reverse phase voltage and an output voltage unbalance rate, and to match a load. To change the connection.

FIG. 4 shows an example of the prior art.

In Fig. 4, 10 is a transformer, a pantograph in contact with the overhead wire.
Primary winding 12 and secondary winding 13, which are fed from 11 and tertiary winding
It has 14 output windings. The secondary winding 13 is the main rectifier 15
Is connected to a main DC motor (not shown) for driving the vehicle. The tertiary winding has two intermediate taps (or multiple taps) and feeds the phase converter 16. The phase number converter 16 is started as a single-phase induction motor using a resistance-phase split start 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 through a starting switch 18 so that the magnetic flux created by the main winding 16a and the auxiliary winding 16b are created. The rotating magnetic field is generated by shifting the phase of the magnetic flux, and the starting rotational force is generated to start up.After the number of revolutions rises, the starting resistor 17 is separated by the starting switch 18, and the load switch 19 is turned on to turn on the three-phase induction motor etc. Supply three-phase alternating current to the load group 20. Since the phase number converter 16 outputs a three-phase AC voltage by a combination of two windings of the main winding 16a and the auxiliary winding 16b, the overhead wire voltage, that is, the input voltage from the tertiary winding 14 of the transformer 10 And the load change, the three-phase output voltage does not become a balanced voltage, but becomes an unbalanced voltage. That is, as in the vector diagram of the output voltage of the phase number converter shown in FIG. 5, the voltage vector W ₀ -Z at the time of no load created by the auxiliary winding 16b of the phase number converter 16 is in the equilibrium state ( It is larger than the voltage vector W ₁ -Z (normally under rated load), and the phase difference with respect to the voltage vector U-V of the U-V phase of the main winding 16 a is also large. On the other hand, the voltage vector W ₂ -Z auxiliary winding 16b which make overload is smaller than the voltage vector W ₁ -Z balanced case, also, the main winding
The phase difference with respect to the voltage vector U-V of the U-V phase of 16a is also small. Therefore, the tertiary winding 14 of the transformer 10 is provided with a plurality of intermediate terminals, and the auxiliary winding 16 that fluctuates as the load current changes.
The connection of the intermediate terminal is changed to match the output voltage of b. FIG. 6 shows the voltage vector when the connection is changed. W ₂ -Z is W ₂ '-Z' in front of the change it is after the change.

[Problems to be Solved by the Invention]

The above-mentioned prior art does not consider the maintenance and the installation space of the transformer output terminal, and there is a problem in securing the installation space and maintainability.

An object of the present invention is to provide a phase number conversion device that is easy to outfit and easy to maintain.

[Means for Solving the Problems]

The above object is achieved by providing one intermediate terminal for unequally dividing the output voltage of the tertiary winding of the transformer and making the voltage fluctuation rate on the multi-turn side larger than the voltage fluctuation rate on the small-turn side.

[Action]

 The operation of the present invention will be described with reference to the drawings.

FIG. 7 shows a vector diagram of each current voltage of the phase number converter. In the figure, the subscripts 0, 1, and 2 indicate 0 when there is no load, 1 indicates when the load is rated, and 2 when it is overloaded. The output voltages V _uv , V _vw , and V _wu are shown only at the rated load.

As shown in FIG. 7, the output currents I _u0 and I _v0 of the tertiary winding have a power factor of the load motor of 0.8 to 0.9 and a power factor of the phase number converter of about 0.5, so that I _u0 > I _{It is v0} . This means that as shown in FIG.
Output voltage is reduced, the phase difference from the voltage of the U-V phase is reduced, and at the same time, the phase difference seen from the apparent midpoint of the U-V phase is reduced and the voltage imbalance ratio is increased. In FIG. 5, Z shows the midpoint of the voltage of the U-V phase, and Z'shows the point moved by the current difference.

Therefore, an intermediate terminal is provided so that the no-load voltage of the tertiary winding is V _uz <V _zv , and the voltage fluctuation rate on the _VZ side (the multiple winding side) is the voltage on the _UZ side (the _decimal winding side). By making it larger than the fluctuation rate, the intermediate terminal voltage of the tertiary winding operates so as to draw the voltage of the auxiliary winding of the phase converter to the V terminal side as the load current increases. As a result, the auxiliary winding output voltage moves on the perpendicular line passing through the midpoint of the tertiary winding output voltage, so that the output voltage of the phase number converter is almost
Since V _vw = V _wu , the voltage imbalance ratio can be reduced.

〔Example〕

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

FIG. 1 is a main circuit diagram showing an embodiment of the phase number converter of the present invention.

In FIG. 1, the number of turns on the U terminal side is V in the tertiary winding 14 of the transformer 10.
One intermediate terminal Z is provided so as to have a smaller number of turns on the terminal side, and the intermediate terminal Z and the terminal of the auxiliary winding 16b of the phase number converter 16 are directly and permanently connected.

The voltage fluctuation rate of the tertiary winding is set so that ε _u <ε _v .

Here, ε _u : UZ phase voltage fluctuation rate of the tertiary winding ε _v : VZ phase voltage fluctuation rate of the tertiary winding As a method of obtaining this relationship, for example, two independent tertiary windings are used. It can be obtained by configuring with windings and selecting the mutual spatial position or the spatial position with the primary winding.

The optimum values of the voltage fluctuation rates ε _u and ε _v are determined by the combination with the phase number converter and the load characteristics, but at least ε _u <ε.
_{If v} , the purpose is achieved.

Further, the voltage vector WZ generated by the auxiliary winding of the phase number converter is advanced by 90 degrees (electrical angle) or more with respect to the voltage vector UV.

The characteristics of the present invention will be described below with reference to the vector of FIG.

In FIG. 2, U-V is the voltage across the U-V terminals shown in FIG. 1, and W-Z is the auxiliary winding 16 of the phase number converter shown in FIG.
The output voltage of b is shown. W ₀ −Z ₀ shows the case of light load, W ₁ −Z ₁ shows the rated load, and W ₂ −Z ₂ shows the case of overload.

As is clear from FIG. 2, as the load current increases,
The output voltage of the phase converter 16 is extremely increased because the voltage drop of the VW phase and the voltage of the WU phase are almost equal to each other due to the drop of the internal impedance of the tertiary winding and the drop of the internal impedance of the phase converter. There is no such thing.

FIG. 3 shows the above state in the relationship of the voltage unbalance ratio to the load capacitance, and FIG. 3 (a) shows an example having two intermediate terminals shown in FIG. 4 in the prior art (b). Shows the case of the present invention.

In the above description, the case where the voltage fluctuation rate of the tertiary winding of the transformer is made unequal has been explained, but the same effect can be obtained even if the tertiary winding and the phase converter are connected via an appropriate impedance. can get.

〔The invention's effect〕

According to the phase number converter of the present invention described above, a rotary type phase number converter having a main winding and an auxiliary winding, which converts a single-phase power source into a three-phase power source, and a pantograph in contact with an overhead wire. The primary winding receives power, the secondary winding is connected to the main DC motor through a rectifier, and the tertiary winding supplies electric power to the phase number converter. A transformer having one intermediate terminal connected to the auxiliary winding of the number converter, the intermediate terminal being provided at an unequal point of the tertiary winding, and Since the voltage fluctuation rate on the number of turns side is made larger than the voltage fluctuation rate on the small turns side, unnecessary heat generation and torque reduction due to the unbalanced voltage of the load motor can be reduced, and the load motor is small and lightweight. Of course, it is easy to secure a fitting space and maintenance is possible. There is simply a say effect.

[Brief description of drawings]

FIG. 1 is a system diagram showing an embodiment of the phase number converter of the present invention, FIG. 2 is a vector diagram showing characteristics of the embodiment of FIG.
FIG. 3 is a characteristic diagram showing the relationship between the load capacity and the voltage imbalance ratio in the embodiment of FIG. 1, FIG. 4 is a system diagram showing a conventional phase number conversion device, and FIGS. Vector diagrams showing the characteristics of FIG. 4, FIG. 7, and FIG. 8 are vector diagrams for explaining the operation of the present invention. 10 …… transformer, 11 …… pantograph, 12 …… primary winding,
13 …… Secondary winding, 14 …… Tertiary winding, 15 …… Main rectifier,
16 ... Phase number converter, 16a ... Main winding, 16b ... Auxiliary winding,
20 …… Load group.

Claims (1)

[Claims] 1. A rotary type phase number converter having a main winding and an auxiliary winding for converting a single-phase power supply into a three-phase power supply, and a primary winding and a rectifying device for receiving power from a pantograph in contact with an overhead wire. A secondary winding connected to the main DC motor via a third winding for supplying electric power to the phase number converter, and the third winding is connected to the auxiliary winding of the phase number converter. And a transformer having one intermediate terminal, wherein the intermediate terminal is provided at an unequal point of the tertiary winding, and
A phase number conversion device characterized in that a voltage change rate on the multi-turn side of the tertiary winding is made larger than a voltage change rate on the small-turn side.