JPS63114575A - Power conversion control device - Google Patents

Abstract

PURPOSE:To perform regenerative operation safely, by controlling the firing angle so that the voltage on the bridge DC side may be changed within a range between the DC upper and lower limit voltage set up in accordance with the source voltage on the bridge AC side in power regenerating operation. CONSTITUTION:A power conversion control device 1 is equipped with an upper limit pattern generation circuit 4, a lower limit pattern generation circuit 5, comparators 6-7, a beta setting circuit 8 and a gate amplifier 9 in order to output the control signal to control its firing angle against a thyristor bridge 3 in a bridge circuit section 2. This comparator 6 compares the DC voltage Ed on the bridge DC side with the DC upper limit voltage EH and outputs a step-up signal betaUP of a control angle of lead beta when Ed>EH. The comparator 7 likewise compares the DC voltage Ed with the lower limit voltage EL to output the step-down signal betaDWN. Receiving both signals, the beta setting circuit 8 outputs the specified control angle of lead signal beta0 and generates a gate signal.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Application Field) This invention provides a power conversion control that performs power change control by controlling the thyristor firing angle of a thyristor bridge capable of reversible AC/DC conversion. Regarding equipment.

(Prior Technology) As is well known, AC electric trains have been widely adopted as electric railway AC trains, in which a rectifier such as a diode bridge or a silice bridge is used to convert AC into DC, and the system is driven by a DC motor. has been done.

In particular, when a SIRISK bridge is applied as a rectifier, it is suitable for power regeneration operation that converts DC back into AC, as it is capable of reversibly converting AC to DC. Energy savings can be achieved through power regeneration.

Incidentally, the firing timing of the iris iris during the power regeneration operation of the thyristor bridge is controlled by manipulating the control advance angle. In this case, the bridge DC voltage is approximately expressed by the following equation (1).

Ed ='-0,9Ea cosβ-(2/π)Xa
Id... (1) However, Ed: DC average voltage Ea: AC power supply voltage β: 1lJII] Lead angle Xa 2 commutation reactance Id: DC current On the other hand, when the thyristor bridge is viewed from the AC power supply side,
The power factor, which is one of the performance measures for a power exchange device, is desired to have a high value.

Also, the DC voltage Ed of the thyristor bridge is as shown in (1) above.
When expressed by the formula, the power factor is approximately proportional to COSβ. Therefore, in order to obtain a high power factor, it is necessary to reduce the control advance angle β.

Furthermore, in order to sustain power regeneration operation, it is necessary to prevent commutation failure of the thyristor, and for this purpose, it is necessary to secure a commutation margin angle expressed by the following equation (2) above a certain value. .

7 = cos −1 [CO5β10<Jx/Ea
) Xa Id co...<2) However, γ: Commutation margin angle The condition is that the value in [ ] on the right side of formula <2) is smaller than 1.

Therefore, it is necessary to set β so that COSβ+Al2Xa Ia /Ea <1.

Moreover, when Xa, ld, and Ea fluctuate, β should be controlled accordingly, or a control advance angle that can secure the commutation margin angle γ under the worst condition, that is, the condition where JlXa Id/Ea is the maximum, is determined. β must be set in advance.

When using the former method of controlling β according to fluctuations in Xa, Id, and Ea, the isolateral internal resistance of the bridge when viewed from the DC side becomes negative. It tends to cause resistance.

Therefore, control of the DC circuit (control of the DC motor in the case of an AC electric vehicle) becomes difficult.

Therefore, in the past, like the latter method (xXa
The silisque bridge was controlled by setting β at a control advance angle that could ensure the commutation margin angle γ under the conditions where ld/Ea was maximum.

However, according to the latter method, since the regenerative operation is performed at a control advance angle β that does not cause commutation failure under the worst conditions, β inevitably becomes large.

Since β is fixed, the regenerative operation is stable, but there is a problem that the power factor is poor.

(Problem to be solved by the invention) In this way, in the conventional technology, the regenerative operation is performed at a control advance angle β that prevents commutation failure under the worst conditions, so the power factor decreases. There was a problem in that regenerative operation was performed in a state where the

This invention was made in view of the above problems, and its purpose is to provide a power conversion control device that can stably perform regenerative operation under a high power factor without considering current changes on the bridge DC side. There is a particular thing.

[Structure of the Invention (Means for Solving Problems)] In order to achieve the above object, the present invention controls the firing angle of each thyristor of a thyristor capable of reversible AC/DC conversion to control power conversion. In this device, during power regeneration operation in which DC power is reversely converted to AC power by the thyristor bridge, a DC upper limit voltage and a DC lower limit voltage are set in response to the power supply voltage on the AC side of the bridge in accordance with the power supply voltage on the AC side. and means for controlling the firing angle of each thyristor on the ship so that the bridge DC side voltage is changed within the range between the DC upper limit voltage and the DC lower limit voltage set by the means. It is characterized by

(Function) According to such a configuration, during power regeneration operation in which DC power is reversely converted into AC power by the Cyrisk bridge, the voltage between the DC upper limit voltage and the DC lower limit voltage set according to the power supply voltage on the AC side of the bridge is Since the thyristor firing angle is controlled so that the bridge DC side voltage is changed within the range of , this control of the thyristor firing angle is completely unrelated to changes in the bridge DC side current.

Moreover, when the thyristor firing angle is controlled in this way, the control advance angle is changed in response to this υItIO so as not to cause commutation failure, so stable regenerative operation is ensured, and the bridge AC When viewed from the side, the power factor is significantly improved.

(Embodiment) FIG. 1 is a block diagram schematically showing a circuit configuration including a power conversion control device according to an embodiment of the present invention.

The power conversion control device 1 of this embodiment includes an upper limit pattern generation circuit 4 and a lower limit pattern generation circuit in order to output a control signal for controlling the thyristor firing angle to the thyristor bridge 3 of the bridge circuit section 2. 5, comparators 6 and 7, a β setting circuit 8, and a gate amplifier 9.

The upper limit pattern generation circuit 4 receives the AC type 8!10 power supply voltage Ea of the bridge circuit section 2 and sets the DC upper limit voltage EH.

The lower limit pattern generation circuit 5 receives the power supply voltage Ea of the same AC power supply 10 and sets the DC lower limit voltage EL.

The comparator 6 compares the DC voltage Ed on the bridge DC side of the bridge circuit section 2 with the DC upper limit voltage EH, and if Ed>E■, the step-up signal Sup of the control advance angle β is set to 1''.
Output as .

The comparator 7 compares the same DC voltage lad with the DC lower limit voltage EL, and outputs the step-down signal βDWN of β as “1” if Ed<EL.

The β setting circuit 8 receives the step-up signal βUP and the step-down signal βDWN of β, and determines that βup=”
1" and βowN="O", the control advance angle signal β is increased by a predetermined value.

Wodekashi, Mata, βUP=t101# and βDWN=11
If it is 111, the control advance angle signal β0 that has been decreased by a certain predetermined value is output, and in other cases, the previously output control advance angle signal β0 is output.

The gate amplifier 9 receives the control advance angle signal β0 output from the β setting circuit 8, and generates a gate signal for each thyristor to turn on and off the thyristor at the firing timing indicated by the control advance angle signal β0. .

In addition, in FIG. 1, 11 is a commutation reactance, and 12 is a commutation reactance.
is a DC circuit.

Next, to explain the operation of the configuration shown in FIG. 1, the voltage lad on the bridge DC side and the current 1d on the DC side are calculated as shown in FIG. 2 by equations (1) and (2). The bridge output characteristics have the following relationship.

In FIG. 2, several straight lines upward to the right indicate the 1d-Ed characteristic when the control advance angle β (β1 to β2) is kept constant, and is β1 minus β2.

Also, the lower right dashed line is the commutation limit line, and the line above this commutation limit line is '?' Area A indicates that commutation fails.

When such a bridge output characteristic is used, the DC upper limit voltage EH and the DC lower limit voltage EL can be set by the upper limit pattern generation circuit 4 and the lower limit pattern generation circuit 5, respectively, as shown by Ell and EL in FIG. For example, the DC voltage Ed on the bridge DC side is comparison 2! ! 6 and 7, they are compared with the DC upper limit voltage E11 and the DC lower limit voltage EL, respectively.

The thyristor firing angle of the thyristor bridge 2 is controlled by the gate signal of the gate amplifier 9 in response to the control advance signal β0 from the β setting circuit 8 which receives the step-up signal βIJP or step-down signal βDWN obtained by this comparison. Therefore, the DC voltage Ed on the DC side of the bridge is changed stepwise within the range between the DC upper limit voltage El-1 and the DC lower limit voltage E, as shown by the thick line.

Therefore, when the DC current 1d is small, the control advance angle is β2
Even if it is set to a smaller value, there will be no commutation failure. When the control advance angle is small, the power factor improves and the DC voltage increases.

In general, if the direction of the DC voltage Ed during the rectification operation of the thyristor bridge is positive, the direction of the DC voltage I'd becomes an opposite negative voltage during the regeneration operation.

Therefore, in the description of this embodiment, the magnitude relationship of the DC voltages Ed will be expressed by comparing the absolute values of the DC voltages, ignoring the signs.

From this point of view, if the DC voltage Ed is maintained at a large value even when the DC current 1d is small, an improvement in increasing the power factor can be achieved.

As described above, in the configuration to which the present invention is applied, the power factor can be greatly improved by controlling β so that the DC voltage Ed is within a certain voltage range, regardless of the magnitude of the DC current 1d. become.

In other words, according to Figure 2, the maximum DC current (80A)
The upper limit EH is the DC voltage obtained by operating at β (= β2) where there is no commutation failure, and this upper limit voltage EH
If the lower limit voltage EL is set to a voltage that is somewhat smaller than EL, and the advance control angle β of the Cyrisk Bridge 3 is controlled so that EL≦Ed≦EH, the area in which it operates with a small advance control angle will increase, and the power will be increased. rate improvement is achieved.

On the other hand, in order to obtain stable regenerative operation, it is preferable to fix the advance control angle as in the conventional method. Therefore, even if this invention is applied to one embodiment, the idea is incorporated and the Ed.
>EH, the control advance angle is increased in steps, when EL > Ed, β is decreased in steps, and when EL≦Ed≦EH, the control advance angle is fixed. .

By manipulating the control advance angle in this way.

Since the control advance angle is fixed for most of the period, stable regeneration operation can be obtained.

More specifically, in FIG. 2, if the straight line Ed-EH is named the upper limit pattern and the straight line Ed-EL is named the lower limit pattern, the slope of this pattern becomes the approximate equivalent internal resistance of the bridge as seen from the DC circuit side.

In this case, if the slope is downward to the right like the commutation limit line, the uniform resistance becomes negative resistance and control on the DC circuit side becomes difficult. However, in one embodiment to which this invention is applied, Since the slope is zero, it has no effect on control on the DC side.

If there is a resistance on the DC circuit side, the slope of the pattern can be made downward to the right as long as the combined resistance of this DC resistance and the bridge equivalent resistance does not become negative, which further improves the power factor. be done.

By the way, as shown in equation (1) above, even if the control advance angle β and the DC current 1d remain unchanged, if the power supply voltage Ea on the bridge AC side changes, the DC voltage E(I Also fluctuates.

Therefore, it is necessary to determine the DC upper limit voltage EH (upper limit pattern) and the DC lower limit voltage EL (lower limit pattern).

In this regard, in one embodiment to which the present invention is applied, the DC upper limit voltage EH and the DC lower limit voltage El are generated according to the magnitude of the power supply voltage Ea on the bridge AC side.
Even if the magnitude of the bridge AC side Ea changes, regeneration operation can always be performed in a region where commutation failure does not occur.

FIG. 3 is a block diagram schematically showing the circuit configuration of a power conversion control device according to another embodiment to which the present invention is applied.

In addition, the power conversion control device of the embodiment includes comparator 6 and comparator 7.
A suppressing means 20 for suppressing the regeneration expiry speed to a low level is provided between the upper limit pattern generating circuit 4. Lower limit pattern generation circuit5. A gate amplifier 9 is provided.

Although not shown, a power conversion control device of another embodiment is electrically connected to a bridge circuit section similar to the bridge circuit section of FIG. 1. ``The suppressing means 20 is
ND circuit 21. Same 22. 23 and NOT[11124
, a comparator 25 , and an OR circuit 26 are connected as shown in the figure, and one input terminal of the NOT circuit 24 and the AND circuit 23 receives a held signal, and the comparator 25 outputs a DC current on the bridge DC side. 1d and IL at the current lower limit value, a predetermined suppressing operation is performed to keep the regeneration expiration speed low.

Next, a description will be given of an aspect of an AC electric train using an actual power conversion control device having such a configuration.

The DC circuit 12 of the bridge circuit section 2 shown in FIG.
For AC trains, DC electric trains are equivalent.

During regenerative operation of a train, this motor is operated as a DC generator. If the generated voltage is Ell and the DC circuit resistance is r, the DC current 1d flowing during regenerative operation is as shown by the following equation (3). become.

Id = (EM-Ed)/r = (kN-Ed)/r -<3
> However, when N is the train speed (motor rotational speed), the motor field magnetic flux is constant, and Em = k N.

On the other hand, in general, when operating a train, when the train speed decreases and the DC current I (l becomes less than a certain current value), the regenerative brake is disabled and the electric brake is switched to the mechanical brake.

If this regenerative brake expiry speed is high, it is desirable to reduce the expiration speed because the wear of the brake shoes is accelerated and the life span is shortened.

In order to lower the expiration speed, as can be seen from equation (3), when the train speed decreases, the DC voltage Ed on the bridge DC side should be reduced so that the DC current 1d does not become too small.

In the configuration of the embodiment shown in FIG. 1, the DC current Id - DC voltage Ed characteristic is as shown by the thick line in FIG. Since the target DC lower limit voltage is near EL, the regeneration expiration speed is high (somewhat dissatisfied).

From this point of view, a power conversion control device according to another embodiment is provided with a suppressing means 2° as shown in FIG. 3 to solve this dissatisfaction.

Next, to describe the effects of other embodiments, ho
The ld signal is a signal that becomes "1" when the train speed becomes low or when the DC circuit meets a predetermined condition, and when this hold signal is 'O', comparators 6 and 7
The output of is directly input to the input βUP and βD of the β setting circuit 8.
Become WN.

Therefore, the movement of the control advance angle signal β0 is similar to that in the embodiment shown in FIG. In other words, when the DC current 1d on the bridge DC side changes from small to large to small, the change in DC voltage Ed is as shown by the thick line in Fig. 4, and EL<Ed
<Maintain the EH relationship.

Now, hold="1" at point A in Figure 4, and) d
>lL. At this time, each output signal of the AND circuits 21 and 22 is 0'', and the DC current is 1 d.
Since the output signal of the comparison circuit 25 which compares the magnitude relationship between the current lower limit value IL and the preset current lower limit value IL becomes "0'°, β0 is fixed."

In this case, the DC voltage lad on the bridge DC side is
As shown in the figure, it becomes smaller as the DC current 1d decreases, that is, as the train speed decreases, and as a result, the regeneration expiration speed decreases.

When the DC current becomes smaller and Id<71, the output of the comparator 25 becomes '1', and thus βu p =
Since it becomes "1", β0 increases in a stepwise manner.

Therefore, the DC voltage Ed becomes even smaller as shown in FIG. Therefore, the regeneration expiration speed can also be lowered.

In this way, in the case of the power conversion control system vi, to which the configuration of the other embodiment shown in FIG. Therefore, the life of the brake shoe can be extended.

[Effects of the Invention] As explained above, when the present invention is configured to control the thyristor firing angle of the thyristor bridge, the current change on the bridge DC side is not taken into account during regenerative operation (high power Since the ratio can be obtained, the equipment (capacity) on the AC power supply side can be made smaller.

Moreover, since the regenerative operation is stable, it saves labor and energy. Furthermore, since the thyristor firing angle can be easily controlled, there are advantages such as ease of maintenance and adjustment of the entire device.

[Brief explanation of the drawing]

FIG. 1 is a block diagram schematically showing a circuit configuration including a power conversion control device according to an embodiment of the present invention, and FIG. 2 is a DC current-DC voltage of a silister bridge in the circuit configuration of the embodiment. Figure 3 is a block diagram showing the outline of another embodiment to which this invention is applied, and Figure 4 is a diagram showing the DC current vs. DC voltage when controlling the thyrisk bridge with the circuit configuration of the other embodiment. FIG. 3 is a diagram showing characteristics. 1... Power conversion control device 2... Bridge circuit section 3... Thyristor bridge 4... Upper limit pattern generation circuit 5... Lower limit pattern generation circuit 6... Comparator 7... Comparator 8 ... β setting circuit 9 ... Gate amplifier 10 ... AC power supply 20 ... Suppression means 21, 22, 23 ... AND circuit 24 ... NOT circuit 25 ... Comparator 26 ...・OR circuit

Claims (2)

[Claims] (1) In a device that performs power conversion control by controlling the thyristor firing angle of a thyristor bridge capable of reversible AC/DC conversion, during power regeneration operation in which DC power is reversely converted to AC power by the thyristor bridge, the AC side of the bridge is A means for receiving a power supply voltage and setting a DC upper limit voltage and a DC lower limit voltage according to the power supply voltage on the AC side of the bridge; A power conversion control device comprising: means for controlling a thyristor firing angle so that a DC side voltage is changed; (2) The means for controlling the thyristor firing angle increases the control advance angle of each of the thyristors stepwise when the bridge DC side voltage is larger than the DC upper limit voltage, so that the bridge DC side voltage becomes the DC lower limit. When the voltage is smaller than the DC voltage, the control lead angle is decreased stepwise, and when the bridge DC side voltage is between the DC upper limit voltage and the DC lower limit voltage, the control lead angle is fixed. The power conversion control device according to scope 1.