JPS6193909A - Synchronous rectifire circuit for differential transformer - Google Patents

Abstract

PURPOSE:To eliminate the need for an intricate phase adjusting operation and to simplify construction without decreasing the detection accuracy of a differential transformer and deteriorating the linearity by subjecting the secondary output of the differential transformer to waveform shaping to obtain a synchronizing signal. CONSTITUTION:This circuit is so arranged as to obtain the synchronizing signal S13 in accordance with the voltage signal S4 from the secondary coil 4 of the differential transformer 1 and therefore the phases of the synchronizing signal S13 and the voltage signal S1 outputted from the secondary side of the differential transformer 1 can be made always to coincide regardless of the frequency of an oscillator 6, the number of coil turns of the transformer 1, the position of a core 5 and temp. conditions. The need for the phase adjusting operation is therefore eliminated at all times, a delay circuit is omitted and the construction is simplified. The distortion of the output voltage signal S14 by a rectifier circuit 14 is obviated and the deterioration in the detection accuracy by the transformer 1 and the linearity thereof is prevented.

Description

Detailed Description of the Invention [Industrial Application Field] The present invention relates to a circuit for rectifying the secondary side output of a differential transformer useful as a linear sensor, and particularly to a circuit for rectifying the secondary side output of a differential transformer useful as a linear sensor. The present invention relates to a synchronous rectifier circuit for a differential transformer that performs synchronized rectification.

[Prior art]

As is well known, differential transformers have high precision linearity,
Since it has very good electrical properties such as output stability and 9 resolution, as well as durability and other mechanical properties, it is used extremely widely as a linear displacement sensor. As an example of a circuit for rectifying the secondary output of a differential transformer, a synchronous rectifier circuit constructed as shown in FIG. 3 has conventionally been provided.

That is, in FIG. 5, 1 is a differential transformer, which, as is well known, has a primary coil, 1 coil, and 2. Secondary coil 3
．． 4 and Core 5) Become. Reference numeral 6 denotes an oscillator, which has a sinusoidal waveform as shown in FIG. 4(d). Reference numerals 8 and 9 represent a buffer and an inverter buffer, respectively, which receive the output of the amplifier 7. 1o is a rectifier circuit that rectifies the outputs of the buffer 8 and the inverter buffer 9, which is shown as a model in FIG. When the input to the select terminal S is at a positive level, contact 1[)b is turned on to allow the output from the inverter buffer 9 to pass. On the other hand, 11 is a delay circuit that delays the voltage signal S6 from the oscillator 6 by a predetermined time, and 12 is a waveform shaping circuit that shapes the output of this delay circuit 1-1 into a rectangular wave and applies it to the select terminal S of the rectifier circuit 10. It is a circuit.

However, in such a configuration, when the AC voltage signal 86 from the oscillator 6 is applied to the primary coil 2 of the differential transformer 1, a value corresponding to the position of the core 5 from the secondary side of the differential transformer 1 is generated. A voltage signal S1 (the waveform of which is shown in FIG. 4(a)) is output, and the voltage signal S1 is amplified by the amplifier 7. Therefore, the buffer 8 outputs a voltage signal 8a having the same phase as the amplified signal (see FIG. 4(b)), and the inverter buffer 9 outputs a voltage signal Sp having the opposite phase to the voltage signal S8 (see FIG. 4(b)). (0)) is output. on the other hand,
The delay circuit 11 provides a voltage signal 511 (see FIG. 4(e)) obtained by delaying the voltage signal S6 from the oscillation M6 by a predetermined time to the waveform shaping circuit 12, and this waveform shaping circuit #812 converts the input voltage A synchronization signal S+z in the form of a rectangular wave as shown in FIG. 4(f) which is inverted at the zero cross point of the signal S11.
is output and applied to the select terminal f of the rectifier circuit 10. As a result, the rectifier circuit 1Q passes the voltage signal S8 from the buffer 8 while the synchronizing signal S12 is at a low level, and the voltage signal S? from the inverter buffer 9 while the synchronizing signal 812 is at a high level. The rectifying circuit 10 outputs a DC E pressure signal 81o as shown in FIG. 4(g). Based on the level of the DC voltage signal 810, the position of the motor 15 can be known.

However, in the conventional configuration described above, since the synchronizing signal 812 is obtained from the primary side of the differential transformer 1 (specifically, from the oscillator 6), there is a drawback described below. That is,
A phase difference always occurs between the primary side lightning voltage (voltage signal 86) and the secondary side voltage (voltage signal S1) of the differential transformer 1 (normally, the secondary side voltage leads the phase). And the phase difference is.

It changes depending on the local wave number of the oscillator 6 and the number of coils Jl/turns of the differential transformer 1. Therefore, in the conventional configuration, the phase difference is adjusted by the delay circuit &S11, and the synchronization signal 812 is
and the respective phases of the voltage signal S1 are made to match.

However, this configuration not only has the disadvantage that the phase adjustment operation is complicated, but also requires two extra extension circuits 11, resulting in a complicated structure. Indeed, the phase difference between the voltage signals S1 and 86 also changes due to subsequent factors such as changes in the position of the core 5, temperature fluctuations, and fluctuations in the oscillation cycle of the oscillator 6. The phase difference between the voltage signals S1 and 86 due to subsequent factors cannot be absorbed. Therefore, in reality, a phase shift occurs between the secondary voltage signal 81- of the differential transformer 1 and the synchronization signal 812 as shown in FIG.
The waveform of o is distorted, resulting in a decrease in the opening degree detected by the pressure device 1 and deterioration of its linearity.

[Purpose of the invention]

An object of the present invention is to prevent the detection accuracy of the differential transformer from decreasing and its linearity to deteriorate even when the secondary output of the differential transformer is rectified in synchronization with a synchronizing signal. To provide a synchronous rectifier circuit for a differential transformer, which can eliminate the need for complicated phase adjustment operations conventionally required, and can also simplify the structure. It is in.

[Summary of the invention]

The present invention provides a synchronous rectifier circuit that rectifies the secondary output of a differential transformer in synchronization with a synchronous signal, in which the synchronous signal is obtained by waveform shaping the secondary output of the differential transformer. It is something.

〔Example〕

An embodiment of the present invention will be described below with reference to FIGS. 1 and 2. However, the same parts as those in FIG. 3 are designated by the same reference numerals and the explanation thereof will be omitted.

In FIG. 1, 13 is a waveform shaping circuit, which receives a voltage signal 84 (see FIG. 2(d)) from the secondary side output of the differential transformer 1, particularly from one of the secondary coils 4. A synchronizing signal S in the form of a rectangular wave as shown in FIG. 2(e) changes at the zero cross point of the input voltage signal S4.
15 is output and applied to the select terminal 8 of the rectifier circuit 14. The rectifier circuit 14 is shown as a model in FIG.
When the input to the select terminal S is at a positive level, the contact 14a is turned on to allow the output from the buffer 8 to pass;
When the input to the select terminal S is at a negative level, the contact 14b is turned on to allow the output from the inverter buffer 9 to pass.

According to the above r4 configuration, since the synchronizing signal 815 is obtained based on the voltage signal S4 from the secondary coil 4 of the differential transformer 1, the synchronizing signal 813 and the voltage signal S4 of the differential transformer 1 are Voltage signal S+ output from the secondary side (Figure 2 (a)
) can always be matched regardless of the frequency of the oscillator 6, the number of coil turns of the differential transformer 1, the position of the core 5, and the temperature conditions. Therefore, the phase adjustment process that was conventionally necessary can be eliminated, and the delay circuit 11 (see FIG. 5) can be omitted, simplifying the structure. In addition, the output voltage signal 5 from the rectifier circuit 14
14 (see @2 Figure)) is not distorted as in the conventional case, and there is no risk of deterioration of the detection accuracy or linearity of the differential transformer 1.

Incidentally, FIGS. 2(b) and 2(C) show the voltage signal 8s from the buffer 8 and the voltage signal S? from the inverter buffer 9, respectively. shows.

〔Effect of the invention〕

According to the present invention, as is clear from the above description, in a synchronous rectifier circuit that rectifies the secondary output of a differential transformer in synchronization with a synchronous signal, the secondary output of the differential transformer is waveform-shaped. This eliminates the risk of lowering the detection accuracy of the differential transformer and deteriorating its linearity, eliminates the need for complicated phase adjustment operations, and further improves the structure. This also allows for simplification.

[Brief explanation of the drawing]

1 and 2 show one embodiment of the present invention, FIG. 1 is an electrical configuration diagram, and FIG. 2 is an output waveform diagram of each part in FIG. 1. Further, FIGS. 3 and 4 show conventional examples, with FIG. 3 being a diagram corresponding to FIG. 1, and FIG. 4 being an output waveform diagram of each part in FIG. In the figure, 1 is a differential transformer, 6 is an oscillator, 8 is a buffer, and 9
13 represents an inverter buffer, 13 represents a waveform shaping circuit, and 14 represents a rectifier circuit. BirH person Thanks Co., Ltd. Figure 1 Figure 2

Claims (1)

[Claims] 1. In a device that synchronizes and rectifies the secondary side output of a differential transformer with a synchronizing signal, a waveform shaping circuit is provided that generates the synchronizing signal by waveform shaping the secondary side output of the differential transformer. A synchronous rectifier circuit for a differential transformer.