JPS598439A - Optical transformer - Google Patents

Abstract

PURPOSE:To reproduce a sinusoidal wave faithful to an original waveform, by giving a secondary output of a transformer to a light emitting diode, transmitting an optical signal corresponding to a positive and a negative voltage and adding a level proportional to the threshold value of a diode for eliminating high harmonic components. CONSTITUTION:A secondary output (a) between terminals 1, 2 of the transformer Tr is applied to light emitting diodes D1, D2 via a temperature cmpensating circuit 2 comprising resistors R1, R2 and a thermister Rt to light respectively the diodes D1, D2 in response to the positive and the negative voltage. This optical signal is transmitted to photodiodes D3, D4 at receiving side on optical fibers F1, F2 to convert the optical signal into an electric signal. A pulsive output is generated at load resistors R3, R4 with this signal to output a pulsive output (b) at an output load resistor R7 of an operational amplifier IC1 to be supplied to operational amplifiers IC2, IC4 to output respective rectangular wave signals C, C'. The signals C, C' are added to the output (b) proportional to a threshold voltage inherent to the diodes D1, D2, the high harmonic components are eliminated and a sinusoidal wave faithful to the original waveform is outputted.

Description

[Detailed description of the invention] The present invention relates to optical transformers. .

Normally, when a light emitting diode is used as a light source for an analog signal, an appropriate bias voltage is applied and the optical output is modulated by an electric signal within a range with good linearity. However, when this light emitting diode is used as a light source of an optical transformer, it is difficult to supply a stable bias voltage because it is installed in a so-called high voltage region. For this reason, in the past, a diode that shared the positive polarity voltage and a diode that shared the negative polarity voltage were combined, and the optical signals obtained by making each diode emit light every half cycle of AC were transmitted separately using two optical fibers. The signal is transmitted, and after photoelectric conversion on the receiving side, the signal is restored to alternating current.

However, when a light emitting diode is used in this way, there are of course eight problems with the threshold voltage inherent to the diode, and it does not emit light during the time period from the zero point of the sine wave alternating current until the threshold voltage is reached, and therefore it cannot be used via an optical fiber. Even if the transmitted optical signal is restored to an electrical signal on the receiving side, only a pulsating current will be obtained and it will not be possible to reproduce a sinusoidal alternating current.

The present invention has been made with the above-mentioned matters in mind, and the secondary side output of the transformer is applied to the light emitting diode, and the positive polarity voltage,
A pulsating output obtained by synthesizing electrical signals based on the optical signals on the receiving side of the optical fiber, in which optical signals obtained in response to negative polarity voltages are transmitted in analog form using optical fibers. A square wave signal is generated in synchronization with t, and this square wave signal is added to the pulsating output at an appropriate level proportional to the threshold voltage specific to the light emitting diode, and harmonics are calculated from the waveform obtained by this addition. This method removes components and attempts to reproduce a sinusoidal alternating current that is faithful to the original waveform.

Hereinafter, the present invention will be explained according to embodiments shown in the drawings. FIG. 1 is a circuit diagram showing an embodiment of the present invention. T
r is a transformer installed in the high potential section, and its terminals 1.2
The secondary side output a appearing in the waveform shown in FIG.
Be given to 2. The light emitting diodes DI and D2 are connected to emit light in response to positive and negative voltages, respectively. The output optical signal is transmitted through optical fiber F1
, F2 to the receiving side. D3 and D4 are photodiodes provided on the receiving side, and the IiJ optical symbol signals are converted into electrical signals by the diodes D3 and D4.

The signal B generates a pulsating output at both ends of the load resistor R5, and a pulsating output b having a waveform as shown in Figure 2 is obtained at both ends of the output load resistor R7 of the operational amplifier IC1. According to the phase relationship 1 between this pulsating output waveform and the waveform of the secondary output a of the transformer 'rr, as shown by the arrow, the light emitting diode D
1, determined by the threshold voltage Vth specific to D2.

Returning to FIG. 1 again, the resistor R3 is a photodiode D5,
In order to balance the output voltage of D4, a variable resistor is used, and the resistor R
5, R4, R5/R between each resistance value of 5 and R6.
3= R6/R4t, x; S relation'e Motase"Ch
7). ICz, IC3, IC4 and ICs are operational amplifiers. The operational amplifier IO2 is a non-inverting feedback type operational amplifier, which amplifies the output voltage of the operational amplifier IC1 by 10R9/8 times using the resistors Re and R9, divides the output voltage into the resistor hole 10SA11, and uses the diode D5 to amplify the output voltage of the operational amplifier IC1. Only the half wave is supplied as a synchronizing signal to the operational amplifier ICs acting as a multivibrator for rectangular wave oscillation via the coupling capacitor C1. Multi-by-break IC3 1
Oscillation RKAT is determined by the capacitance value of capacitor C2 and resistance Rsz
, T=20 due to the resistance values of R13, R14M and 几15.
It is determined as zR1zln 1+H-A N. If this oscillation period T is selected to match the period of the sine wave alternating current of the secondary output a of the transformer Tr shown in FIG. 2(a), the output of the multivibrator IC5 is
), a rectangular wave signal C with a repetition period T that is synchronized with the pulsatile output is obtained. This rectangular wave signal C is divided into an appropriate level by resistors 16 and 17 to form a rectangular wave signal C.
′ is obtained. This square wave signal C' and the differential amplifier C1
When the pulsating current output from the filter is input to the operational amplifier IC4 and differentially amplified, a distorted waveform AC d containing odd harmonics is obtained as shown in FIG. In addition, the resistors R18, R
19 uses a low resistance so as not to saturate a low-pass active filter F, which will be described next. This low-pass active filter F has a resistor hole 20. It is composed of R21 and R22, a capacitor 03.04, and an operational amplifier C5, and its new station frequency is 100Hz. Since the 6th harmonic of AC at the commercial frequency and higher attenuation is large, and only the fundamental wave component is output with the set gain, the phase delay determined by the integral time constant (c5・IL2o) of resistor R20 and capacitor c5 is When the correction is made by the differential circuit DF consisting of the capacitor C5 and the resistor hole 25, the result shown in Fig. 2 (e
) An output waveform e as shown in the figure is obtained between the output terminal 6 and the ground.

This output waveform is completely similar to the sine waveform of the secondary output a of the transformer Tr.

In other words, the rectangular wave output C, which is the output of the multivibrator ICs, is converted to the threshold voltage v specific to the light emitting diodes DI and D2.
If you set it to an appropriate value commensurate with th, the transformer Tr
Even if the output varies over a wide range, a proportional relationship can always be maintained.

According to the present invention, the secondary side output of the transformer is applied to the light emitting diode, and the optical signals obtained in response to the positive polarity voltage and the negative polarity voltage are transmitted in analog form via the optical fiber, and the optical signals are transmitted in analog form through the optical fiber. A rectangular wave signal synchronized with the pulsating output obtained by combining the electrical signals obtained by photoelectric conversion on the receiving side of the optical fiber is added to the pulsating output at a level t in proportion to the threshold voltage specific to the light emitting diode. However, since high-frequency components are removed from the waveform obtained by this addition, it is possible to reproduce a completely distortion-free sine wave alternating current similar to the secondary output of the transformer, and therefore the accuracy is improved. High detection is possible.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram showing one embodiment of the present invention, and FIG. 2 is a waveform diagram for explaining the present invention in detail. Tr... Transformer Dl, D2... Light emitting diodes F1, F2... Optical fiber a... Secondary output of transformer b... Pulsating output c, c'... Square wave Signal e...Output waveform Patent applicant Nissin Electric Co., Ltd. (and one other person)

Claims (1)

[Claims] The secondary output of the transformer is applied to a light emitting diode, and the optical signals obtained in response to positive polarity voltage and negative polarity voltage are transmitted in analog form using an optical fiber. generates a rectangular wave signal synchronized with the pulsating output obtained by combining electrical signals based on the optical signal, and applies this rectangular wave signal to the pulsating output at a level proportional to a threshold voltage specific to the light emitting diode. An optical transformer that obtains an output waveform similar to the secondary side output by adding the above-mentioned secondary side outputs and removing harmonic components from the waveform obtained by the addition.