JPS6240947B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a control method during regenerative operation of a thyristor conversion device in which unit converters having a thyristor bridge configuration are connected in cascade, and in particular to a control method capable of improving regenerative power. .

Generally, the regenerative power that can be output by the same thyristor conversion device is smaller than the driving power. For this reason, this type of thyristor conversion device installed on AC electric railway vehicles is required to be able to obtain sufficient regenerative power even during braking operation, and various control methods have been proposed to improve regenerative power. .

Conventionally, thyristor conversion devices installed on AC electric railway vehicles have been developed by dividing the secondary winding of the transformer installed on the train into multiple parts in order to reduce harmonic current flowing through the power supply overhead wire. Generally, a system is adopted in which a unit thyristor converter is connected to each line, and the DC sides of these unit thyristor converters are connected in cascade.

In such a thyristor conversion device, during braking operation in which load power is regenerated to the power source by performing a reverse conversion operation, the maximum firing advance angle βmin of the thyristor ensures a commutation margin angle θ ₀ defined by the thyristor. In order for this to happen, the value must be as follows:

βmin≧θ ₀ +U〓 ………(1) However, U〓 is the commutation overlap angle.

Here, since the commutation overlap angle U〓 is proportional to the reactance on the AC side, in cases where the reactance on the AC side fluctuates greatly, such as in electric railways, even under operating conditions where the reactance on the AC side is maximum, the commutation margin angle θ ₀ must be reserved.

On the other hand, in a rectifier in which the secondary winding of a transformer is divided into multiple parts and unit rectifiers are connected in series, each secondary winding interferes with each other when the rectifier commutates, resulting in a complicated commutation operation. In order to maximize the regenerative power of the rectifier, the ignition advance angle may be controlled so that the commutation margin angle θ ₀ of the rectifier always reaches a certain specified value. In the case of AC electric railways, the reactance on the AC side fluctuates as mentioned above, and the commutation operation of each rectifier is not the same due to commutation interference between windings, so each rectifier is set to a constant minimum firing advance. It is very difficult to always maintain the commutation margin angle θ ₀ at a constant value by controlling the angle βmin. From this perspective, conventionally,
So-called constant margin angle control that detects the commutation margin angle of each rectifier and controls the firing of each rectifier at the same minimum firing advance angle so that the smallest commutation margin angle among the rectifiers is equal to or greater than a specified value. A method has been proposed.

However, when applying vernier control to one of the rectifiers, if the constant margin angle control method is applied to the vernier control winding, the commutation margin angle will not be constant when switching control of the vernier winding, and the commutation margin angle will change. There are cases where it becomes smaller than the specified value, which has the disadvantage of leading to commutation failure. In addition, vernier control means that one rectifier performs phase control while the other rectifiers are turned on.
-Specifies a control method that performs only OFF operation.

FIG. 1 is a main circuit diagram of a conventional thyristor conversion device, showing a case where the secondary winding of a transformer Tr is divided into four (W ₂₁ , W ₂₂ , W ₂₃ , W ₂₄ ). In addition,
In Fig. 1, each divided secondary winding W ₂₁ , W ₂₂ , W ₂₃ , W ₂₄ of the transformer Tr is connected to a rectifier Rec.
1, Rec2, Rec3, and Rec4 are connected, and these rectifiers Rec1 to Rec4 are connected in cascade to supply electric power to the electric motor M. Also,
Each rectifier from each secondary winding W ₂₁ to W ₂₄ of the transformer Tr
The minimum commutation margin angle signals Rec1 to Rec4 are input to the detection circuit 10 to detect the minimum commutation margin angle, and then this minimum commutation margin angle signal is transmitted to each rectifier Rec1 via the control circuit 12 and the phase control circuit 14. ~Rec4
The configuration is such that each rectifier Rec1 to Rec4 is controlled with a constant margin angle.

The windings of each rectifier when the rectifiers Rec1 to Rec4 shown in Fig. 2 and Fig. 1 are fired at the same firing advance angle.
Operating waveforms of ₂₁ to W ₂₄ (output currents i ₁ to i ₄ and output voltages v ₁ to v ₄ are shown. If the commutation operation is explained with reference to Fig. 2, the predetermined commutation angle θ of the minimum ignition advance angle β min When the _four rectifiers Rec1 to Rec4 are commutated at the same time, the rectifiers Rec1 and Rec2 start commutation due to the commutation interference of the four windings _W21 to _W24.During this time, for example, Rec4 cannot be commutated. Because, Rec4
is subject to commutation interference, which causes a commutation voltage (referred to as a negative commutation voltage) having a polarity in the reverse bias direction for the new ignition thyristor in Rec4. This negative commutation voltage has a polarity in the forward bias direction for the thyristor that has been passing current in Rec4 and is about to have its current reduced to zero, and this is equal to the voltage v in Figure 2. This can be seen from the waveform in ₄ . When commutation of rectifier Rec1 ends at a predetermined angle θ ₂ , the commutation voltage of rectifier Rec2 becomes negative (however,
Due to its small magnitude, the voltage v ₂ in FIG.
It is not clearly shown in the waveform of ) The change in current is reversed and the commutation margin angle of rectifier Rec1 is θ
It becomes ₀₁ . Next, the commutation of the rectifier Rec3 ends at a predetermined angle θ ₃ , and the commutation margin angle becomes θ ₀₃ . Similarly, the commutation of the rectifier Rec2 ends at the predetermined angle _θ4 . Finally, the rectifier Rec4 completes commutation, and its commutation margin angle becomes the specified value θ ₀ . Therefore, constant margin angle control in this case is based on the commutation margin angle θ ₀₁
~ θ ₀₄ is detected, and the detection circuit 10 detects the smallest commutation margin angle (θ ₄ in the example shown in FIG. 2) among these, and this commutation margin angle θ ₀₄ becomes greater than or equal to the specified value θ ₀ . The minimum firing advance angle βmin of each rectifier Rec1 to Rec4 is controlled by the control circuit 12 and the phase control circuit 14.

FIG. 3 shows how the control of the vernier control winding is switched by performing the above-described constant margin angle control. Next, the operation at the time of control switching of the vernier control winding will be explained based on FIG. First, the rectifier Rec
If 1 is a vernier controlled rectifier, the cycle (A)
Control of rectifier Rec1 is completed (rectifier Rec1
When the leading phase control angle β becomes 180°, the rectifier
Rec1 output voltage becomes almost zero), next cycle
In (B), the output of the rectifier Rec2 is set to zero (freewheel operation), and the vernier control rectifier Rec1 is fired at the same minimum firing advance angle βmin as in cycle (A). In this case, before cycle (A), the minimum ignition advance angle βmin is determined so that the minimum commutation margin angle (rectifier Rec4 indicates the minimum commutation margin angle in Fig. 3) is equal to or greater than the specified value θ ₀ . ing. However, since the windings commutated in cycle (B) change, the commutation interference of each winding also differs. Therefore, cycle (A)
Even if ignition is performed with the same minimum ignition advance angle βmin, for example, the commutation margin angle of rectifier Rec4 will change, and in some cases, as shown in the figure, θ _0b may be smaller than θ _0a , leading to a risk of commutation failure. There is sex. That is, the conventional constant margin angle control system has a drawback that the constant margin angle control system is disturbed when switching the control of the vernier control winding.

Therefore, as a result of various studies and improvements to overcome the drawbacks of the control method in the thyristor conversion device described above, the inventor of the present invention determined that the minimum firing advance angle of the vernier control winding of the vernier control rectifier is the minimum of that of other rectifiers. By making the rectification overlap angle of the vernier control winding larger than the ignition lead angle and switching the control of the vernier control winding, the commutation of the vernier control winding can be prevented from affecting the commutation of other rectifiers. ,
We have found that the constant margin angle control system can be operated stably.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a control method that can ensure a specified commutation margin angle even when switching control of a vernier control winding in a cascade-connected thyristor converter.

In order to achieve the above object, in the present invention, at least one thyristor converter of a thyristor converter formed by cascading a plurality of thyristor converters is operated in a vernier control reverse conversion operation, and the other thyristor converters are operated in a free manner. In a control system that regenerates load power to the power supply by operating the wheel or operating at the same minimum firing advance angle, the maximum control delay angle of a vernier control thyristor converter is converted into an advance angle when the other thyristor converters are operated with the same value. It is characterized in that the commutation overlap angle is set larger than the minimum firing advance angle of the commutation overlap angle.

Next, embodiments of a control method for a cascaded thyristor conversion device according to the present invention will be described in detail with reference to the accompanying drawings.

FIG. 4 shows a circuit diagram of a thyristor conversion device showing one embodiment of the present invention. The embodiment shown in FIG. 4 is basically the same as the circuit diagram shown in FIG. 1, and the same reference numerals are given to the same components and the explanation thereof will be omitted. In this embodiment, between the control circuit 12 which inputs the minimum commutation margin angle signal detected by the detection circuit 10 and outputs a predetermined control signal, and the phase control circuit 14 of each rectifier Rec1 to Rec4, The phase control angle of the vernier control rectifier is determined by the commutation overlap angle U from the minimum firing advance angle βmin during a certain period of time when switching the control of the vernier control rectifier.
A control circuit 16 is connected and arranged to control such that .

FIGS. 5 to 9 show operating waveform diagrams (output voltages) of the rectifiers Rec1 to Rec4 when the control according to the present invention is performed. Figure 5, all rectifiers Rec
1 to Rec4 are operating at the minimum firing advance angle βmin. Figure 6, Vernier control rectifier Rec
1 shows a case where the control delay angle α and the control advance angle βmin are asymmetrically controlled, and the other rectifiers Rec2 to Rec4 are controlled with the minimum ignition advance angle βmin. FIG. 7 shows a state in which the control of the vernier control rectifier Rec1 has ended (the control delay angle α is zero). FIG. 8 shows the state immediately after the control is switched from the vernier-controlled rectifier Rec1 to another rectifier Rec2. That is, in FIG. 8, the rectifier Rec2 is shifted to freewheel operation, the vernier control rectifier Rec1 is set to the control delay angle αmax, and the control advance angle is set to the minimum firing advance angle βmin. In addition, Fig. 9 shows
This figure shows details of the commutation operation shown in FIG. 4.

FIG. 10 is a wiring diagram of thyristors T ₁₁ , T ₁₂ , T ₁₃ , and T ₁₄ showing details of the vernier-controlled rectifier Rec1, and when the control of the rectifier Rec1 is switched, thyristors T ₁₁ to _{T 14} are activated. The order is shown in FIG. Asymmetric control during the inverse conversion operation is performed as follows. i.e. for example thyristor
T ₁₁ and T ₁₃ are always fired with the minimum firing advance angle β min, and thyristors T ₁₂ and T ₁₄ are fired with the control delay angle α
The firing is controlled to be variable between α=0 and α=αmax. In this case, conventionally, the firing advance angle conversion value of the maximum control delay angle αmax is selected to be equal to βmin. In other words, the relationship is αmax=π−βmin. Switching from the mode of FIG. 7 to the mode of FIG. 8 corresponds to switching the control angle α of thyristor ₁₂ and T ₁₄ from α=0 to α=αmax. The present invention attempts to prevent the rectifier Rec1 from entering commutation interference immediately after the switching by starting the commutation of the vernier-controlled rectifier Rec1 earlier than the remaining rectifiers. It is something to do. FIG _. 9 shows, for example, a time point corresponding to the maximum control delay angle _αmax (the first
FIG. 1 shows a waveform diagram of the DC voltage e _d1 and the AC side current i _s1 of Rec1 when the thyristor T ₁₂ is fired due to the arrival of θ ₁ (corresponding to θ 1 in FIG. 1). By the ignition of thyristor T ₁₂ , the current that has been flowing to the AC side via thyristor T ₁₄ is commutated to thyristor T _12. When this commutation is completed, the current on the AC side becomes zero and the thyristor
A freewheel operation mode is established in which the current is bypassed via T ₁₂ and T ₁₁ . The angle of the commutation overlap period during the transition from the commutating operating mode to the freewheeling operating mode is indicated by U〓. After the completion of this commutation overlap period, the minimum firing advance angle βmin
A time point corresponding to (corresponding to θ ₂ in FIG. 11) arrives, at which point the thyristor T ₁₃ is fired.
This allows thyristor T ₁₂ to
The current that was bypassed to T ₁₁ begins to be diverted from thyristor T ₁₂ through the alternating current side to path D, which flows through thyristor T ₁₃ . The commutation overlap period during the transition from the freewheeling mode to the commutating mode is indicated by the angle U ₁ . At the point in time corresponding to the minimum firing advance angle βmin when the thyristor _T13 is fired, the other rectifiers Rec2~
Also in Rec4, an ignition operation is performed and commutation is started. Therefore, during the latter commutation overlap period (U〓 ₁ ), the rectifier Rec1 is connected to the other rectifiers Rec2~
Mutual commutation interference occurs with Rec4. However, even immediately before switching thyristor T ₁₃ or T ₁₁ , firing was controlled at a time corresponding to the minimum firing advance angle βmin, so the commutation margin angle control circuit had already taken into account the commutation interference. Since the minimum firing advance angle βmin is determined at , there is no need to consider this commutation interference as a problem. However, the former commutation overlap period (U〓) is α
= 0, so it does not overlap with the commutation operation period of other rectifiers Rec2 to Rec4. Immediately after switching, αmax = π - βmin as in the conventional case. This overlaps with the commutation operation period of the other rectifiers Rec2 to Rec4. Therefore, according to the present invention, the commutation overlap period (U〓) is started earlier than the conventional one by Δθ, and the commutation overlap period (U 〓) should be completed. In this case, the control delay angle αmax at the time of control switching is determined as follows.

αmax=π−βmin−Δθ (2) In the above equation (2), Δθ only needs to be larger than the commutation overlap angle U〓 of the thyristor fired at the control delay angle.

FIG. 12 shows a specific embodiment of the control circuit shown in FIG. 4 according to the present invention. That is, in FIG. 12, reference numeral 18 detects the voltage v ₁ of the vernier control winding W ₂₁ immediately after the commutation ends at the ignition delay angle and the voltage v ₂ immediately before the vernier control winding W 21 is ignited at the ignition advance angle. This is a voltage detection circuit. Also, reference numeral 20
is a detection circuit that detects the commutation overlap angle U at the ignition delay angle of the vernier control rectifier Rec1. Then, the voltage detected by the voltage detection circuit 16
v ₁ and v ₂ are input to a divider 22 to obtain a calculation output of v ₁ /v ₂ . Next, the output of this divider 22 and the output of the detection circuit 20 are inputted to a multiplier 24 to obtain a calculation output of U=KU ₀ ·v ₁ /v ₂ . The output U〓 of the multiplier 24 obtained in this way and the output (minimum firing advance angle) βmin of the control circuit 12 are inputted to the calculator 26, and the control delay angle α is calculated as shown in the following equation.
Calculate and output max.

αmax=π−βmin−U〓 (3) The fact that the above equation (3) is obtained will be explained based on the operating waveforms in FIG. 13. FIG. 13 shows the voltage and current waveforms on the AC side of the rectifier Rec1 in the state immediately before switching (the mode shown in FIG. 7). During the commutation period U ₀ of the rectifier Rec1, no commutation operation is performed in the other rectifiers Rec2 to Rec4, so during the commutation period U ₀ , the commutation of the vernier control winding W ₂₁ is independent of the influence of the other windings. Vernier controlled rectifier Rec
This is done only by the reactance X seen from the first winding. Here, assuming that the winding voltage of the vernier-controlled rectifier Rec1 during the U ₀ period is approximately linear,
The reactance X is determined by the following equation.

X≒ _v1・_U0 /2Id……(4) Also, as shown in Fig. 9, other rectifiers Rec2~
Commutation overlap period U before Rec4 starts commutation
If 〓 is completed, the commutation of the vernier control winding W ₂₁ is not affected by other windings even during this period U 〓, so the reactance X seen from the winding of the vernier control rectifier Rec1 (i.e., This is done only by X) in equation (4). Therefore, the commutation overlap angle U
If the winding voltage of the vernier-controlled rectifier Rec1 during the period is assumed to be a constant value _v2 , the following equation holds true.

U=≒Id・X/v ₂ ......(5) The following equation is obtained from the above equations (4) and (5).

U〓≒1/2・v ₁ /v ₂・U ₀ ………(6) However, since the value v ₂ should originally be the winding voltage at the time corresponding to αmax, it is impossible to obtain it in advance. Can not. Therefore, the value immediately before switching (Fig. 13) is used as _v2 . Therefore, we need to use a value smaller than the original value for v ₂ to find U〓, but as you can see from equation (6), we need to use a value slightly larger than the original value for U〓. It means to anticipate. In other words, a margin is provided for freewheeling to occur between the completion of U〓 and the start of _U〓1 , so the expected error is an error in the safe direction. Said
As is clear from equation (6), by appropriately selecting the constant K of the multiplier 24 in FIG.
In the circuit configuration shown in the figure, the commutation overlap angle U can be easily determined.

As is clear from the foregoing, according to the present invention, when switching the control of the vernier control winding in the vernier control rectifier, the maximum The advance angle conversion (π-αmax) of the control delay angle αmax can be made larger than the minimum firing advance angle βmin by at least the commutation overlap angle U〓, and as a result, even when switching the control of the vernier control winding, a constant margin angle can be maintained. The control system can be operated stably.

Therefore, if the method of the present invention is applied to an AC electric railway vehicle equipped with a cascade-connected thyristor conversion device,
The regeneration rate of regenerated power is increased, and economical operation can be achieved.

Although the preferred embodiments of the present invention have been described above, it goes without saying that various design changes can be made without departing from the spirit of the present invention.

[Brief explanation of the drawing]

Fig. 1 is a circuit diagram showing a conventional cascade-connected thyristor converter, Fig. 2 is an operating waveform diagram of the output current and output voltage of each rectifier shown in Fig. 1, and Fig. 3 is a vernier control winding shown in Fig. 1. FIG. 4 is a circuit diagram of a cascade-connected thyristor conversion device showing an embodiment of the method of the present invention, and FIGS. 5 to 9 are operating waveforms of each rectifier shown in FIG. 4. Figure 10 is a detailed circuit diagram of the vernier control rectifier shown in Figure 4, Figure 11 is a firing waveform diagram of each thyristor shown in Figure 10, and Figure 12 is a diagram of the control circuit shown in Figure 4. A detailed circuit diagram showing the embodiment, FIG. 13 is an operating waveform diagram of the vernier control rectifier shown in FIG. 12. Tr...Transformer, M...Motor, _W21 , _W22 ,
W ₂₃ , W ₂₄ ...DC side winding, Rec1, Rec2, Rec
3, Rec4... Rectifier, T ₁₁ , T ₁₂ , T ₁₃ , T ₁₄ ...
Thyristor, 10...detection circuit, 12...control circuit, 14...phase control circuit, 16...control circuit,
18...Voltage detection circuit, 20...Detection circuit, 22
...Divider, 24...Multiplier, 26...Arithmetic unit.

Claims (1)

[Claims] 1 At least one thyristor converter of a thyristor converter device formed by cascading a plurality of thyristor converters is operated in vernier control reverse conversion operation, and other thyristor converters are operated in freewheel operation or with the same minimum firing advance angle. In a control system that regenerates load power to the power supply using A control method for a cascade-connected thyristor conversion device characterized by setting only the angle larger.