JPS585527B2 - Hand-painted hand warmer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION When semiconductor rectifying elements such as silices, diodes, or transistors are connected in series, the most important thing is to equalize the voltages shared among the series-connected elements.

However, these semiconductor devices generally have different characteristics that directly or indirectly affect their blocking ability, so some means of compensating for these differences is required in order to equalize the shared voltages. be.

FIG. 1 is an example of a conventional correction means in the series connection of two cyrisks.

In the same figure, 1 and 2 are SCRs connected in series, and 11 and 21 are due to the difference in leakage current between SCRs 1 and 2 in the forward and reverse directions.
A resistor connected in parallel with SCRI and 2, respectively, to prevent the shared voltage from excursion, and a capacitor 12
and resistor 13 in series, and capacitor 22 and resistor 2
The series circuits No. 3 are circuits (hereinafter referred to as CR absorbers) that absorb commutation surges and share the transient voltage of SCR1 and SCR2, respectively.

In other words, the externally applied voltage applied between terminals 8 and 9 is
The two equal resistances 11 and 21 are used to forcibly divide the voltage into two.

However, this method has two major drawbacks.

First, if the difference in leakage current between SCR1 and SCR2 is large, the values of the resistors 11 and 21 to compensate for this need to be quite small, which increases power consumption and makes it impractical. If the operating frequency is high, the impedance of the above-mentioned CR absorber becomes less than (the series resistor 11 or the resistor 21), and the correction effect of the resistor 11 and the resistor 21 cannot be expected.

Therefore, it is conceivable to select and use elements with a small difference in leakage current to solve the first drawback, but it is technically impractical to carry out such selection one by one.

On the other hand, the second drawback becomes a problem in the high frequency inverter of the silice type, which has become extremely popular in recent years.

In this case, the voltage must be equalized by the CR absorber itself, but in that case, as described below,
Special constant changes must be made.

Particularly in forced commutation type inverters, which account for most of the high frequency inverters of the silice type, the shared voltage between the series elements varies greatly depending on the application status of the reverse voltage.

For example, the reverse recovery charge Q of two series-connected Cyrisks
If there is a large difference △QR in R, the C of the CR absorber
The relationship △V=△Q/C (1) holds between the difference △■ in the shared voltage of the thyristor, and a large value of C has the effect of suppressing △■ small.

For this reason, even if the capacity is sufficient to absorb commutation surges, the capacity value is insufficient for C to suppress △V to a certain design value, and the capacity of C must be increased. Become.

However, if the capacitance of C is increased, the power consumption in the resistance of the CR absorber increases in proportion to it, so there is a limit to the method of reducing ΔV by increasing C of the CR absorber.

Furthermore, it is possible to reduce △Q and reduce △■, but it is not practical to measure and select reverse recovery charges one by one, similar to the above-mentioned screening for leakage current. It's hard to say.

The present invention, as a means of equalizing shared voltages, reduces power consumption without increasing the capacity C of the CR absorber.
The purpose is to provide a circuit that virtually reduces the amount of energy to almost zero.

FIG. 2 shows the basic configuration of the present invention.

Here, 5 is a voltage suppressor, which has the function of suppressing the voltage across the capacitor of the CR absorber to a certain value or less.

That is, in FIG. 2, the voltage suppressor 5 is composed of a Zener diode 15 having a breakdown voltage of 2 and a diode 14 connected for the purpose of blocking the forward direction of the cyrisk group.
It consists of

Assume that the reverse recovery charge QR of SCR2 is larger than QR of SCR1.

Most of the external reverse voltage VR(1) which is about to be applied between the terminals 8 and 9 by the commutation circuit is applied across the SCRI, that is, between the terminals 8 and 10, in response to the fast reverse recovery of the SCRI.

At this time, in order for the unrecovered thyristor SCR2 to undergo reverse recovery, a reverse recovery current expressed by is required to flow.

Here, ■C(t) is the voltage across the CR absorber capacitor 12 of SCR1, and R is the resistance 13 of the CR absorber.
is the resistance value of

Therefore, the reverse recovery of SCR2 is derived from the reverse recovery of SCR1. There will be a delay by the time to determined by .

Making this delay time to as small as possible is a means of equalizing the shared voltages, but in the case of conventional CR absorbers using only small capacitors, the voltage Vc(t) across the capacitor 12 increases over time. Since the value of i(t) approaches the external reverse voltage VR(t), the value of i(t) becomes very small, and the time to required to finish discharging ΔQR is generally long.

However, as in the present invention, the terminal voltage V of the capacitor 12
If we add a means to suppress C(t) within a certain value vZ, VC(t) will not exceed VZ, so the value of i(t) will not suddenly become small as in the conventional circuit, and equation (3) Generally, the required to is extremely short.

By adding a voltage suppressor in this way, SCR
2 is strongly promoted, but if to is to be shortened without using a voltage suppressor, the only way to shorten to is to increase the capacitance of the CR absorber capacitor 12, and this
As already mentioned, this is a major drawback that leads to an increase in power consumption.

Of course, by adding a voltage suppressor, a large reverse recovery current flows through the resistor 13, so the power loss of the resistor 13 tends to increase, and the voltage suppressor itself does not consume power.

However, the power dissipation in resistor 13 is much smaller than that of increasing the capacitance of the capacitor to achieve the same effect in the conventional manner.

In addition, regarding the loss of the voltage suppressor itself, for example, when using a Zener diode, if VZ is appropriately selected for the reverse voltage ■R (1), the period during which the Zener diode breaks down can be shortened. It is also possible to suppress the power consumption slightly.

In this way, according to the present invention, without increasing the capacitance of the conventional CR absorber capacitor, by simply adding a voltage suppressor to both ends of the capacitor, the power consumption can be shared with a slight increase in the resistance and the power consumption in the voltage suppressor. This has the great effect of equalizing the voltage.

In the above example, a Zener diode is used as the voltage suppressing element of the voltage suppressor 5, but it goes without saying that this is not limited to the Zener diode, and a selenium constant voltage element or the like may also be used.

FIG. 3 shows an example in which the present invention is implemented in a series connection of transistors, in which the emitter of transistor 4 and the collector of transistor 3 are connected in series, and a similar structure as shown in FIG. A voltage suppressor 5 is connected to both ends of the capacitor of the CR absorber,
Similar to the series connection of thyristors shown in FIG. 2, the voltages applied to the emitters and collectors of the transistors 3 and 4 are equalized without any particular increase in the power consumption of the CR absorber.

[Brief explanation of the drawing]

Fig. 1 shows a conventional circuit for equalizing the voltage sharing of each si-risk when two si-risks are connected in series, Fig. 2 shows a circuit according to an embodiment of the present invention, and Fig. 3 shows a circuit according to another embodiment of the present invention. be. In the figure, 1 and 2 are SCRs, 3 and 4 are transistors,
5 is a voltage suppressor, 12 and 22 are CR absorber capacitors, and 13 and 23 are CR absorber resistors. 14 is a diode, and 15 is a Zener diode.

Claims (1)

[Claims] 1. In a series connection of semiconductor elements, a voltage controller is provided that controls the voltage across each capacitor to be approximately the same when a reverse voltage is applied to each semiconductor element in parallel with a capacitor of a CR absorber in parallel with each semiconductor element. A series connection circuit of semiconductor elements, characterized in that they are connected.