JPS6410133B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates in particular to a ramp function voltage generator for measuring the rate effect of a thyristor.

The principle of a ramp function voltage generator is shown in FIG.
By flowing a constant current I from the constant current circuit 1 into the capacitor C, a voltage v expressed by equation (1) is generated across the capacitor.

V=1/C∫ ^t ₀ i·dt=I/Ct (1) As can be seen from equation (1), since the current is constant, this voltage v becomes a ramp function that increases in proportion to time. Further, the slope dv/dt of this ramp function is constant and is expressed by equation (2).

dv/dt=I/c (2) From equation (2), it can be seen that the slope of the ramp function can be changed by changing either the current value I or the constant of the capacitor.

A simple example of the constant current circuit 1 is shown in FIG.
Here, the constant current characteristics of the transistor 5 are utilized. That is, by keeping the voltage of the bias power supply 6 applied between the base and emitter of the transistor 5 constant, the voltage from the power supplies 6 and 8 is transmitted through the resistor 7,
Capacitor C can be supplied with a constant current. Switch 9 is for discharging the charge of the capacitor. Note that although this figure shows an example using a pnp transistor, it is possible to construct a similar circuit using an npn transistor.

In this circuit, the slope of the ramp function can be changed by using the voltage of the bias power supply 6 and the resistor 7 as parameters, or by using the capacitor C as a parameter. The former corresponds to changing I in equation (2).

Conventionally, when changing the slope angle of a ramp function continuously, the following method has been used.

That is, the voltage of the bias power supply 6 is set to the voltage shown in FIG. 3a.
It is increased stepwise for each period T as shown in _Vi .
The period T is a sufficient time for the output v to reach the saturation voltage of the transistor 5, and by operating the switch 9 at the timing of bv _D every time the output v reaches the saturation voltage of the transistor 5,
Discharge the accumulated charge in the capacitor.

As a result, a waveform Cv having a slope corresponding to the bias voltage values v ₁ , v ₂ , and v ₃ is obtained at the output end for each period T. By minutely changing the bias voltage, the slope can be changed almost continuously.

However, such a method has the drawback that the bias voltage value becomes too large when trying to vary the slope over a wide range;
It is not realistic to set the voltage to 100V or more.

As a method to solve this drawback and change the slope of the ramp function more widely, a method is used in which a voltage variable method is used in combination with a constant variable method using a low resistance, a capacitor, etc. FIG. 4a shows a conventional example of such a method, in which the capacitor is variable.

The constant current transistor 5 that can vary the base-emitter voltage has a different constant between the collector and ground (usually by a different order of magnitude, such as 1 pF, 10 pF, and 100 pF)
Capacitors C ₁ , C ₂ , C ₃ are connected to relays 20 to 22, respectively.
The configuration is such that they are connected in parallel via. The slope of the output voltage waveform when each capacitor is connected with the voltage of the bias power supply 6 kept constant is shown by broken lines 23 to 25 in FIG.

By covering the range between the respective slopes by varying the bias voltage, it is possible to continuously change the slope angle of the ramp function over a wide range.

However, since this method uses mechanical contacts, for example, in the case of relays, the operating time (ON time),
The recovery time (OFF time) takes time on the order of milliseconds. In addition, in the case of a micro switch, etc., a stabilization time for chattering is added. This time is always added to each switching, and in a case like the present invention in which the rise is continuously changed, it becomes a large time that cannot be ignored. Therefore, when automating measurements, etc.
The measurement time could not be shortened, which was a major obstacle to high-speed measurement.

It is an object of the present invention to continuously and widely change the slope angle of a ramp function waveform, for example for measuring the rate effect of a thyristor, by changing the circuit constants of a constant current circuit without using mechanical contacts. An object of the present invention is to provide a ramp function waveform voltage generator that can be varied at high speed.

The present invention provides a lamp equipped with a constant current circuit in an integrating capacitor, which can obtain a voltage waveform in the form of a ramp function by supplying a constant current to the capacitor, and whose slope angle can be continuously changed within a certain range. Focusing on the function generation circuit, we installed multiple circuits each consisting of a constant current circuit and an integrating capacitor as a means of varying the slope angle of the ramp function waveform continuously over a wide range and at high speed. It is designed so that the outputs of each can be taken out in an additive manner.

FIG. 5 shows an embodiment of the present invention, in which pnp transistors 30, 31, 32 are connected with low resistors 33, 34, 35 and a voltage variable circuit 3 between their respective emitters and bases.
6, 37, and 38 are provided in series, and constitute a constant current circuit together with an operating power source 48 between the base and ground.

The voltage variable circuits 36 to 38 are connected to the switching control circuit 29
are controlled to operate sequentially. Also,
Integrating capacitors C ₁ , C ₂ , and C ₃ are connected between the collector and ground of each transistor as loads (these constants are chosen to have values of different digits, such as 1 pF, 10 pF, and 100 pF). ),
The voltage across each capacitor is input to a summing circuit 39 and appears at an output 40.

Now, if the voltage variable circuit 36 is selected by the signal from the control circuit 29, the integrating capacitor
At both ends of _C1 , as shown in FIG. 6a, a ramp function voltage waveform is obtained whose slope changes (increases) from a solid line to a broken line as time passes. Then, when the slope of the voltage waveform reaches the broken line, the next voltage variable circuit 37 is selected by the control circuit 29. This allows the integrating capacitor to
At the terminal _C2 , a ramp function voltage waveform appears whose slope changes from the solid line to the broken line in FIG. Similarly, a ramp function voltage waveform whose slope changes from the solid line to the broken line in the figure c appears in the capacitor _C3 . These outputs are output from an output terminal 40 via an adder circuit 39. Therefore, the waveform shown in FIG. 6d is obtained at the output end 40, the slope of which changes continuously from the solid line to the broken line.

In this manner, according to this embodiment, the slope angle of the ramp function voltage waveform can be varied over a wide range and at high speed without using mechanical contacts.
Therefore, by using the present invention, it is possible to speed up the rate effect measurement of thyristors and the like. In addition,
The case where there are three constant current circuits is shown here, but
It is of course possible to add more.

A specific example of the adder circuit 39 suitable for use in FIG. 5 is shown in FIG. The cathodes K of the diodes 51 to 53 are commonly connected to form the output terminal 40, and the anode sides are connected to the output terminals 41, 42, and 42 of each constant current circuit, respectively.
43.

Each diode prevents backflow of the output signal when the other diodes are operating, so the output terminal 40
, the output ramp function voltage waveforms of each constant current circuit shown in FIG. 5 are continuously output. Although this adder circuit is simple and inexpensive, it also has drawbacks such as the inability to achieve high voltage resistance and high speed at the same time.

FIG. 6 shows another specific example of the adder circuit, in which the diode in FIG. 7 is replaced with a diode-connected transistor circuit, which can achieve both high breakdown voltage and high speed. In other words, according to this adder circuit, the breakdown voltage can be provided at the base-collector junction,
It is easy to increase the speed by transistor operation.

FIG. 9 shows another embodiment of the present invention, in which a voltage variable circuit 60 is shared by the constant current transistors 30, 31, and 32. Further, transistors 61, 62, and 63 are provided between the emitter and base of each transistor,
Together with the switching control circuit 29, it constitutes a selection circuit.

By the switching control circuit 29, the transistor 61
When the transistor 62 and 63 are turned off and turned on, the constant current transistor 30 is selected. At this time, current is supplied from the voltage variable circuit 60 to the capacitor C ₁ through the resistor 33 and the transistor 30.

Similarly, the transistor 62 is turned off, the transistors 61 and 63 are turned on, and the transistor 3
1 is selected, capacitor C ₂ , and if transistor 32 is selected, capacitor C 2 is selected.
A current is supplied to C ₃ respectively. As a result,
At the output end 40 of the adder circuit 39, a ramp function voltage waveform as shown in FIG. 6d is obtained.

As described above, by adopting the circuit configuration shown in FIG. 9, the number of voltage variable circuits can be reduced, and a ramp function voltage generator that is simpler, less expensive, and more reliable can be obtained.

As explained above, according to the present invention, it is possible to obtain a ramp function voltage generator that can change the slope of the ramp function voltage over a wide range and at high speed. Moreover, it becomes possible to perform measurements at high speed.

[Brief explanation of the drawing]

Figure 1 is an explanatory diagram of the basic principle of ramp function voltage generation, Figure 2 is a specific circuit diagram for implementing the principle of Figure 1, Figure 3 is a waveform diagram for explaining its operation, and Figure 4 is a diagram explaining the basic principle of ramp function voltage generation.
5 is a block diagram of an embodiment of the present invention, FIG. 6 is a waveform diagram for explaining the operation, and FIGS. 7 and 8 are diagrams for explaining the operation. A circuit diagram of the adder circuit used, FIG. 9, is a block diagram of another embodiment of the invention. 29...Switching control circuit, 36-38, 60...
Voltage variable circuit, 39...addition circuit, 40...output end.

Claims (1)

[Claims] 1 A plurality of constant current circuits each equipped with an active current control element, a plurality of integrating capacitors connected in series to each constant current circuit, and a current value of each constant current circuit at a predetermined time interval within a predetermined range. Current control means connected to each constant current circuit so as to sequentially change the current;
1. A ramp function voltage generator comprising: a switching control circuit that controls the operation of each current control means; and an addition circuit that adds terminal voltages of a plurality of integrating capacitors in time series.