JPS5840424B2 - Thyristor temperature control unit - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement of the Cyrisk commutation circuit, and provides a novel commutation circuit.

Conventional separately excited commutating inverters have the problem of not being able to provide commutation capability in a region where the voltage of the AC system on the load side is low.

Furthermore, cycloconverters and the like have the disadvantage that the utilization rate of cycloconverters is extremely poor.

On the other hand, typical conventional forced commutation methods for Cyrisk are:
The capacitor voltage is used to reverse bias the cyrisk and extinguish it.

Among these, the type called a voltage source inverter requires a feedback diode, and when used for reversible conversion, the direction of the current is reversed, which is disadvantageous for reversible conversion with other AC systems.

On the other hand, the type called a current source inverter has a drawback in terms of the voltage applied to the commutating capacitor and the SIRISK, as will be described later.

Since the present invention is more effective when used as a current source impark, the problems of the conventional current source forced commutation method will be explained in more detail.

FIG. 6 is a circuit diagram of the principle of the conventional forced commutation method using a capacitor and its operating waveform diagram.

Assume that current (2) is flowing through main thyristor 1b-series diode 2b load (or AC system) 500b.

At this time, the capacitor 4 is charged to the illustrated polarity.

Next, when the main thyristor 1a is turned on at time point (2), the main thyristor 1b is turned off, and the current (2) is commutated to the main thyristor 1a, the capacitor 4, the diode 2b, and so on.

However, although the main thyristor 1b has been extinguished, the ultimate goal of commutating the current (2) to the load 500a has not yet been achieved.

Next, at time point ■, the voltage ■4 of capacitor 4 is equal to the load 5.
The combined line back electromotive force e of 00a and 500b reaches 500.

After this point, the polarity of the impedance drop voltage of the loads 500a and 500b is reversed for the first time, the diode 2a starts conducting current, overcomes the electromotive force e500, and the load t
Commutation from 2b to 12a is initiated.

Then, commutation of the load current is completed at time point (3).

In the above commutation process, the peak value ■ of the capacitor voltage V4.

is the sum of the back electromotive force er at time point (2) and the overcharge voltage Δ■o between time point (2) and (2).

Now, the commutation inductance between B and -B2 with a load of 500 is L
If the capacitance of the commutating capacitor is C, then the overcharge voltage △Vc-I σ is 50,000, so the capacitor voltage peak value Vc is Vo=er+I S//B=VT Hy...
It is given by (1) (see Figure 6 b-a-2b-e).

Then, the cyrisk applied voltage peak value VTaY41 is equal to the capacitor voltage peak value.

On the other hand, the required capacitor capacity cannot be determined due to the constraint of the thyristor turn-off time (reverse bias time between time points 1 and 2), but is determined by the 1 degree of the thyristor applied voltage in equation (1).

That is, the sirisk applied voltage peak value VTHY and the capacitor voltage ■.

It is inevitable that the voltage will be higher than the electromotive force peak value of the AC system 500.

Also, as can be seen from the above explanation, it is not a turn-off condition, but
Since the force of the load current commutation condition is a constraint, △
vo=rv4f°C is valid, and at time ■～
It cannot be said that the capacitor current during the period (2) plays an essentially important role.

By the way, if the electromotive force of the load 500 is ensured,
Separate commutation can be performed simply by advancing the firing phase.

Therefore, it is economically advantageous to operate forced commutation only in the low voltage region and perform separately excited commutation in most of the high voltage region.

However, in the conventional device, the capacitor operates unavoidably, resulting in a commutation dead time corresponding to the time from point 1 to point 2.

Further, the capacitor is charged positively and negatively by at least the line-to-line peak value voltage of the AC system 500.

For this reason, it has been difficult to reduce the number of forced commutation means by utilizing other excitation commutation in the high voltage region.

This invention has been made in view of the drawbacks of the conventional commutation method detailed above.

An object of the present invention is to provide a novel commutation circuit that focuses on current commutation in a load, an alternating current path, or an alternating commutation branch circuit.

Another object is to provide a commutation circuit suitable for current type impark without commutation dead time.

Yet another objective is to reduce the required commutating capacitor voltage.

Yet another objective is to reduce the required si-risk voltage.

Still another object is to provide a commutation circuit suitable for utilizing forced commutation in a low voltage region and performing separately excited commutation in a high voltage region.

That is, the narrower the forced commutation working voltage range, the more the forced commutation means is reduced in proportion to the working voltage range, providing a novel commutation circuit suitable for auxiliary forced commutation. purpose.

FIG. 1 and FIG. 2 are diagrams showing an embodiment of the principle of the present invention and its operation waveform diagram.

Now, the operation when commutating the current from the main thyristor 1a to the main thyristor 1n will be explained.

In the initial state, current source system 300 - branch connection point A - diode 2a - main thyristor 1a - branch branch 500a -
A current ■ is flowing through the current source system 300.

Here, the branch branches 500a to 500n refer to the current source system 30.
0 current ■ is shunted and distributed through the main thyristors 1a to 1n to each l branch (each one branch in the load circuit) of the load 500, for example, one phase of a rotating electrical machine. windings and transformer windings connected to rotating electrical machines.

The capacitor 4n is connected to the charging/discharging thyristor 52n from the charging/discharging source 53n and the accelerator 5. n and is charged in advance to the illustrated polarity during the period from time point 1 to time point ■.

Next, at time point (3), the main thyristor 1n is fired, and the commutating voltage application auxiliary thyristor 3n is fired.

As a result, the current {circle around (2)} also begins to flow to the capacitor 4n, the auxiliary thyristor 3n, the main thyristor In, and the shunt branch 500n.

And 4n 3n-In 500n-500a
A closed commutation loop 1a-2a-4n is formed.

In this closed loop, the charging voltage of the illustrated polarity of the capacitor 4n is the internal electromotive force (speed electromotive force of a rotating electric machine, etc.) of the branch branch 500a...500n related to commutation at the time of commutation. Since it is sufficiently larger than
Even when the internal electromotive force e500 has the opposite polarity (negative) to the charging pressure, sufficient commutation can be achieved.

When the internal electromotive force e 500 and the commutation capacitor voltage have the same polarity in the commutation closed loop, both the internal electromotive force and the capacitor voltage act harmonically on the commutation.

Thus, the current in the main thyristor 1a decreases and finally reaches zero at time point (3).

The current of the external force, the main sirisk 1n, reaches the current ■ of the current source system 300.

At this point (3), the main thyristor 1a is turned off, and the reverse bias voltage applied at this time is the closed loop combined electromotive force and is approximately equal to the remaining capacitor voltage.

Furthermore, the capacitor 4n is discharged with a current 2 via the auxiliary thyristor 3n and the main thyristor 1n.

Then, at time point (3), the capacitor voltage reaches zero.

After this point, current 2 flows through the diode 2n, the main thyristor 1n, and the branch branch 500n, completing the commutation.

As described above, in the commutation circuit of the present invention, the current in the branch branch 500 such as the load starts commutation from the beginning, so the commutation delay is small.

After commutation, the capacitor current is commutated to the diode 2, and the capacitor is always operated at a constant voltage, so it is not affected by the voltage of the shunt branch 500, such as the load, and is not overcharged.

In this commutation method, the peak-to-peak voltage V of the capacitor voltage required for commutation.

0. is given by a quadratic equation similar to equation (1).

Here, er is the resistance to the back electromotive force when the current is commutated against the back electromotive force. The pressure change amount is Δvo.

This FIG. 1 embodiment is unipolar.

In contrast, in conventional devices, the same voltage changes polarity and the peak-to-peak voltage is twice as high.

In comparison, the required voltage for the capacitor of the present invention may be lower.

(This will become clearer in the examples shown in FIGS. 3 to 5, which will be described later.

) Furthermore, if the load AC system 500 has established a sufficient electromotive force, commutation can be performed by the distributed power.

Therefore, if the ignition of the auxiliary thyristor 3 is stopped at this time, there will be no interference with the separately excited commutation, and the charging voltage of the auxiliary commutation capacitor will not be interfered with at all.

Therefore, if the commutation circuit of the present invention is used in the resistance voltage region (low voltage and low frequency in normal motor control), the commutation means can be simple and requires only an extremely low voltage.

Furthermore, MP capacitors can be used for high-voltage, large-capacity devices, and electrolytic capacitors can be used for low-voltage, medium- and small-capacity devices.

FIG. 3 shows still another embodiment of the present invention, which is an example of application to a bridge type inverter.

In the figure, commutating capacitors 4a, 4b and charging/discharging means 5a, 5b are shared within the positive group or within the negative group, respectively.

Further, the charging/discharging sources 53a and 53b are configured to act in series with the capacitor voltage when the auxiliary cylindrical switch for applying commutated voltage is turned on.

That is, in the above-mentioned operation, at the time point (■) when the commutation is completed,
The commutating capacitors 4a and 4b are charged and discharged at the source voltage E with the polarity shown.

will be charged only. And charge/discharge thyristor 5□3,5
When □b is ignited, the reactors 51a and 5b and the capacitor vibrate and are charged with the same voltage in the polarity shown.

Next, when the auxiliary thyristors 3a to 3f are ignited, the sum of the capacitor voltage and the charging/discharging source acts as a commutating force.

In this way, the capacitor changes polarity, and its peak-to-peak voltage is the same as in Fig. 1 and 1 in Fig. 6 of the conventional device.
/2.

FIG. 4 shows a configuration in which a pulse transformer 54 is used to further share the commutation capacitor.

In this case, the capacitor 4 is charged and discharged by the thyristor 5□a,
52b, and the voltage at this time is transmitted via the transformer 54 to the auxiliary sirisk 3 of the positive group or negative group, respectively, and is used as the commutated voltage as described above. .

FIG. 5 shows an embodiment in which the reactor 51 is omitted from the embodiment shown in FIG. 3, and charging and discharging of the capacitor 4 to both polarities is used to improve the utilization rate of the capacitor.

The principle circuit in the case of the two-way branch shown in FIG. 2A will be explained.

First, when the branch branch 500b and the thyristor 1b are energized, the auxiliary thyristors 3b and 5□b are ignited, and the capacitor 4 is charged with the current 2 via the auxiliary power source 53 to the polarity shown.

Next, when commutating the current to the thyristor 1a and the shunt path 500a, the auxiliary thyristors 3a and 52a are fired, and the sum of the capacitor voltage and the voltage of the auxiliary power supply 53 is the diode 2a.
is applied in the opposite direction.

R1] A commutating voltage is applied so that the current in the main thyristor 1a and the branch branch 500a increases, and the current in the thyristor 1b and the branch branch 500b decreases.

When this commutation is completed, the capacitor 4 is charged by the auxiliary power supply voltage to the opposite polarity as shown.

Similarly, the sum of this reverse polarity charging voltage and the auxiliary power supply voltage is used for the next commutation from main thyristor 1a to 1b.

It should be noted that FIG. 5 is an embodiment for the case of three branch branches, and can be similarly applied to the case of any number of branch branches.

Furthermore, by applying these, it can be used in push type connection and various other types of circuit connection configurations.

As described above, according to the present invention, rapid commutation can be performed by applying the charging/discharging voltage of the capacitor in antiparallel to the diode connected in series with the main silica.

In addition, since there is no overcharging of the capacitor and the peak-to-peak voltage of the capacitor is low, the required VA of the capacitor can be reduced.
Capacity is reduced.

In addition, along with this, the applied voltage of the si-risk also decreases and is reduced.

Furthermore, the commutation circuit of the present invention can be used as an auxiliary commutation means in a range where the internal electromotive force of the branch branch (for example, an AC system) is low, and the operation can be stopped in a high voltage range to reduce the internal electromotive force of the branch branch. If separately excited commutation is used, they will not interfere with each other at all.

Furthermore, even when operated in a high voltage range, it harmonically promotes commutation and contributes to the above separately excited commutation.

The commutation circuit of the present invention does not interfere with separately excited commutation (natural commutation), which is commutated by the internal electromotive force of the branch branch (main circuit), so it uses the commutation action of the commutation capacitor. Depending on the voltage range, the required voltage and capacity of this commutation means are reduced.

Furthermore, when the operating frequency varies proportionally to the operating voltage, such as in motor control, the frequency duty is also reduced.

Therefore, a DC electrolytic capacitor or an AC electrolytic capacitor can be used as a commutating capacitor.

Furthermore, in high voltage equipment, inexpensive low voltage MP capacitors can be used.

As described above, the present invention has many methots.

[Brief explanation of drawings]

FIG. 1 is a principle-embodiment diagram of this invention, FIG. 2 is an operation waveform diagram of FIG. 1, FIGS. 3 to 5 are diagrams showing other embodiments of this invention, and FIG. The figure is a circuit diagram and an operation waveform diagram showing a conventional commutation method. In the figure, 1 is the main circuit, 2 is a rectifier, 3 is an auxiliary circuit for applying commutated voltage, 4 is a capacitor, 5 is a charging/discharging means, 300 is a current source path, and 500 is a branch circuit (load, AC system, etc.) ).

Claims (1)

[Claims] 1. A Cyrisk circuit configured by connecting in parallel at least two branch circuits in which a Cyrisk and a load line are connected in series, and a current source that is connected to this Cyrisk circuit and flows a current to be passed to one of the branch circuits. and a current path having a current path, and commutates the current flowing in the current path between the branch paths, a rectifying element connected in series and in the forward direction to each of the above cyrisks, and a rectifying element connected to the rectifying element in series and in the forward direction. and a commutation means which is connected in parallel with each other and is composed of a commutation power supply, a capacitor charged from this power supply, and a commutation voltage application sirisk that applies the charging voltage of this capacitor with opposite polarity to each of the rectification elements. Cyrisk commutation circuit.