JPS5917894B2 - pulse width signal converter - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a pulse width signal converter that electrically isolates a minute input DC signal and obtains a pulse width signal corresponding to the input DC signal.

SUMMARY OF THE INVENTION An object of the present invention is to realize a device that can electrically insulate minute DC signals with a simple configuration and obtain two types of pulse width signals related to the magnitude of the minute signal.

FIG. 1 is a connection diagram showing one embodiment of the present invention.

In the figure, lL12 is an input terminal to which input DC signal Ei is applied, C is a capacitor connected between input terminals 11 and 12, Dl and D2 are diodes connected in parallel with opposite polarities, and these are like a parallel diode circuit. It consists of

TR is primary winding n1, secondary winding n2 and tertiary winding n3
21 and 22 are output terminals connected to both ends of the secondary winding n2, and O8 is a pulse generator connected to the tertiary winding n3.

The primary winding n1 of the transformer TR is connected to input terminals 11 and 12 via a parallel diode circuit, and these constitute an input circuit, and the secondary winding n2 constitutes an output circuit.

FIG. 2 is a characteristic diagram of a parallel diode circuit, and as shown, the applied voltage e1 and the flowing current 11 have a nonlinear relationship.

In the device configured in this manner, the turns ratio between the primary winding n1 and the secondary winding n2 of the transformer TR is set to 1=1, and a pulse signal i having positive and negative symmetry is applied to the tertiary winding n3.

, the equivalent circuit is as shown in FIG.

In the equivalent circuit of Figure 3, the switch S is a diode D
1. This shows the switching operation of D2,
When a positive pulse is applied from the pulse generator O8,
The switch S is connected to the contact a side (diode D1 is conductive), and when a negative pulse is applied, the switch S is connected to the contact side (diode D2 is conductive).

The diodes D1 and D2 are both expressed by a forward voltage Δ.

Now, when the positive pulse +Io is being applied from the pulse generator O8, the switch S is equivalent to being connected to the contact a (diode D1 is conducting), and the inductance of the coil representing the transformer TR is LlIf the current flowing there is iL, then at the rise of the pulse (1)
The formula holds true.

Similarly, when a negative pulse -Io is applied from the pulse generator O8, the switch S is equivalent to being connected to the contact point (diode D2 is conductive), and at the falling edge of the pulse (2) The formula holds true.

In formula (1), iL is from 1■o to ■.

The time t1 required to reach this point can be expressed by equation (3).

Also, in equation (2), iL or ■.

The time t2 from t2 to -Io can be expressed by equation (4).

Therefore, the output terminal 21 of the secondary winding n2 (output circuit)
, 22, a voltage signal is generated only during the time when the current (it, ) flowing through the coil is changing, and this voltage signal e is an input DC signal as shown in equations (3) and (4). There are two types of pulse width signals having pulse widths (time widths) tl and t2 related to Ei.

FIG. 4 is an operational waveform diagram of the circuit of FIG. 3.

From the pulse generator O8, Io, - as shown in FIG.
I.

Assuming that a pulse signal that changes as shown in FIG.
Electron a11 as shown in the figure opening. 12 flows at the rising edge of the pulse and at the falling edge of the pulse, and a current IL as shown in FIG. 4C flows through the inductance L.

Here, the time t1. until 11°12 becomes zero is t1. t2 is expressed by equations (3) and (4).

When a linearly rising or falling current iL as shown in FIG. 4C flows through the inductance L, the output terminals 21 and 2
2 has a pulse width t1.2 as shown in FIG. A signal e at t2 can be obtained.

FIGS. 5 and 6 are connection diagrams showing other embodiments of the present invention.

The embodiment of FIG. 5 has a plurality of (here, only two inputs are shown) input DC signals Ei2. Ei2 can be converted into a pulse width signal in parallel,
The tertiary windings n3 of each transformer TR are connected in series.1.
In addition, a driving pulse signal i is supplied from a pulse generator O8.

It was designed to give

Here, the pulse generator O8 is composed of a positive and negative polarity constant current source C8 including a square wave oscillator OSC, a diode bridge circuit that inputs the output signal from this oscillator, and a constant current element Q that utilizes the constant current property of the FET. This is what I did.

In the embodiment of FIG. 6, the primary winding n1. A transformer TR having a secondary winding n2 is used, and the pulse generator O8 is connected to the secondary winding n2.
It is connected to both ends of 2.

In this case as well, the operation is exactly the same as that of the circuit shown in FIG.

Note that the pulse generator O8 is connected to both ends A of the primary winding n1.

It is also possible to connect between B and B.

7 to 9 are connection diagrams showing other examples of parallel diode circuits.

FIG. 7 shows a structure in which a plurality of diodes connected in series are connected in parallel.

The forward voltage Δ can be adjusted by changing the number of diodes connected in series.

FIG. 8 shows a structure in which transistors are diode-connected and connected in parallel with each other with opposite polarities.

FIG. 9 shows a configuration in which Zener diodes are connected in parallel.

In addition, in the above embodiment, the ratio between the primary winding n1 and the secondary winding n2 of the transformer TR does not have to be 1:1.

Further, the capacitor C connected between the input terminals 11 and 12 may be omitted.

As explained above, according to the present invention, it is possible to realize a pulse width signal converter having the function of insulating a minute signal and converting it into a pulse width signal and having various features as listed below. .

(1) Since the entire structure can be realized using a transformer and diode circuit, the structure can be simple and compact.

(11) Since there are no mechanical contacts, long life and high reliability can be expected.

(If a pulse generator is connected to the tertiary or secondary winding of the curved transformer, there is no need for a power supply or control signal on the primary winding, resulting in high intrinsic safety.

[Brief Description of the Drawings] Fig. 1 is a connection diagram showing one embodiment of the present invention, Fig. 2 is a characteristic diagram of a parallel diode circuit used in the present invention, and Fig. 3 is a characteristic diagram of a parallel diode circuit used in the present invention.
The diagram shows both circuits of the circuit in Figure 1, and Figure 4 shows its operating waveform diagram.
5 and 6 are connection diagrams showing other embodiments of the present invention, and FIGS. 7 to 9 are connection diagrams showing other examples of parallel diode circuits. 11.12...Input terminal, 2L22...Output terminal,
D...Parallel diode circuit, TR...Transformer, n
l...Primary winding, n2...Secondary winding, n3...Tertiary winding, O8...Pulse generator, C...Capacitor.

Claims (1)

[Claims] 1. A transformer having a primary winding and a secondary winding, a nonlinear circuit having a nonlinear voltage-to-current characteristic such that current flows when the applied voltage exceeds a predetermined value, and an input DC signal that is Circuit means that feed the primary winding of the transformer through the circuit, the primary winding of the transformer. A means for applying a rectangular wave pulse signal to either a secondary winding or a tertiary winding provided in the transformer is provided, and a pulse width signal corresponding to the input DC signal is obtained from the secondary winding of the transformer. Pulse width signal converter. 2. The pulse width signal converter according to claim 1, which uses a circuit in which diodes are connected in parallel with opposite polarities as the nonlinear circuit. 3. The pulse width signal converter according to claim 1, which uses a circuit in which diode-connected transistors are connected in parallel with each other with opposite polarities as the nonlinear circuit. 4. The pulse width signal converter according to claim 1, which uses a circuit in which Zener diodes are connected in parallel with opposite polarities as the nonlinear circuit. 5. A patent claim in which the means for providing a rectangular wave pulse signal is constituted by a rectangular wave oscillator, and a positive and negative polarity constant current source including a diode bridge circuit and a constant current element that receives an output signal from the rectangular wave oscillator. The pulse width signal converter according to range 1.