WO2008009195A1

WO2008009195A1 - Signal compensation method for passive signal isolators

Info

Publication number: WO2008009195A1
Application number: PCT/CN2007/001599
Authority: WO
Inventors: Xiangyang Yin; Dingmin Mo
Original assignee: ZHANG, Jiaoru
Priority date: 2006-07-11
Filing date: 2007-05-17
Publication date: 2008-01-24
Also published as: CN1913062A; CN100517528C

Abstract

A signal compensation method for passive signal isolators, which adds a compensation transformer in the passive signal isolator circuit, wherein a primary coil of the compensation transformer is connected to a primary or secondary coil of the main transformer in the circuit in serial, one lead of the secondary coil of the compensation transformer passes through an annular core of the main transformer in the direction of current increase, and then the lead is connected according to the function of the compensation transformer and the turn number ratio of the primary and secondary coils of the compensation transformer is got by the necessary error compensation, which can increase the field strength by 1/n times of the main transformer when the secondary coil of the compensation one passes through the annular core of the main one, so that the isolation transmission of signals can get the compensation by 1/n times and precision of the passive signal isolator is improved.

Description

Signal compensation method for passive signal isolator

Technical field

The present invention relates to a simple circuit for implementing a signal compensation method for a passive signal isolator.

Background technique

In the prior art, the passive signal isolator comprises a complementary triode pair and a capacitor.

DC-DC half-bridge circuit, half-bridge self-excited oscillation circuit mainly composed of D101 and drive transformer, 1:1 signal-coupled main transformer and secondary rectifier circuit of main transformer, wherein the primary transformer of the main transformer in the circuit connection The drive transformers are connected in series, and the secondary of the drive transformer is directly connected to the half-bridge self-excited oscillation circuit. The passive signal isolator chopping the input DC signal through the half-bridge circuit and the half-bridge self-oscillation circuit to make it an AC signal, and then coupling the energy from the primary to the secondary by means of a 1:1 main transformer coupling. Level, and finally rectify the output to drive the load. Since in theory the signal coupling process follows the law that the turns ratio of the primary and secondary coils is equal to the inverse ratio of the primary and secondary coil currents, the isolated transmission of the signal can be achieved.

However, the energy of the signal passes through the transformer coupling process due to factors such as copper loss and iron loss. It is inevitable that there is energy loss, or the magnetic flux is diverging outward, or the secondary end can not achieve ideal rectification and other factors. It does not completely follow the 1:1 transmission to form an error. The error of this signal is often expressed as the current signal at the secondary side is slightly smaller than the primary end signal.

Summary of the invention

The object of the invention is to use a simple and easy to implement method for this small error Compensation is performed to achieve higher signal transmission accuracy of the passive signal isolator.

The above object can be achieved by the following technical measures: a signal compensation method for a passive signal isolator, in which a compensation transformer is added in the passive signal isolator circuit, the primary of the compensation transformer and the primary or the main transformer in the circuit The secondary series, the one end of the compensation transformer secondary is connected to the lead wire to increase the output current through the main transformer toroidal core and then according to the function of the compensation transformer; the primary and secondary coil turns ratio of the compensation transformer is compensated by the required compensation The error size is derived. The compensation transformer has a larger turns ratio of the coil, assuming that the ratio is n, that is, the number of turns of the secondary coil is n times the number of turns of the primary coil; when an alternating current I flows through the primary coil of the compensation transformer, the secondary The coil generates an alternating current of IX 1/n; in the case where the secondary of the compensation transformer passes through the toroidal core of the main transformer, the magnetic field strength of the main transformer can be increased by 1/n, so that the isolated transmission of the signal is 1/n. The compensation amount is doubled to improve the accuracy of the passive signal isolator.

The invention adopts a driving transformer in a passive signal isolator circuit as a compensation transformer. The primary of the main transformer is connected in series with the driving transformer, and one end of the driving transformer secondary is connected to the toroidal core of the main transformer, and then connected to the half bridge. In the oscillation circuit.

The primary transformer of the compensation transformer of the present invention is connected between the main transformer and the primary of the drive transformer, and one end of the compensation transformer secondary is connected to the other end of the secondary of the compensation transformer after passing through the main transformer toroidal core.

The primary of the compensation transformer of the present invention is connected in series with the secondary of the main transformer, and one end of the compensation transformer secondary is connected to the other end of the secondary of the compensation transformer after passing through the toroidal core of the main transformer.

In order to compensate for the convenience of the connection of the secondary of the transformer after passing through the toroidal core of the main transformer Stable, after the secondary of the compensation transformer passes through the main transformer core and is wound and then connected. The above object can also be achieved by the following technical measures: A signal compensation method for a passive signal isolator, a winding is added to a main transformer in a passive signal isolator circuit, and a driving transformer in a passive signal isolator circuit After the secondary is connected in series with the additional winding, it is connected to the half-bridge self-oscillating circuit, and the turns ratio of the additional winding is determined by the error of the required compensation.

The invention adds a compensation transformer, and the secondary of the compensation transformer penetrates into the main transformer, and uses the energy of the primary coil of the main transformer to superimpose the strength of the magnetic field line required for the error compensation inside the main transformer core, thereby compensating for the transmission distortion of the signal, and the loss The current signal is compensated. Moreover, this compensation is a proportional compensation for the current signal, which does not affect the linearity of the signal, and at the same time improves the accuracy.

DRAWINGS

1 is a schematic diagram of a connection according to Embodiment 1 of the present invention;

2 is a schematic diagram of connection according to Embodiment 2 of the present invention;

3 is a schematic diagram of a connection according to Embodiment 3 of the present invention;

4 is a schematic diagram of connection according to Embodiment 4 of the present invention;

Figure 5 is a schematic diagram of the connection of the fifth embodiment of the present invention;

6 is a schematic diagram of a connection according to Embodiment 6 of the present invention;

Figure 7 is a schematic view showing the structure of the secondary of the compensation transformer passing through the main transformer core.

detailed description

As shown in Figure 1, Π+ is the positive terminal of the signal input to the current signal, and Π- is the negative terminal of the signal input to the current signal. Q100 is an NPN and PNP complementary triode pair, and a complementary triode pair Q100 The capacitors C104, C105 form a typical DC DC half-bridge circuit. Resistors R101, R102 are triode-to-bias current resistors. The capacitors C100, C101, C102 and D101 (triode pairs composed of NPN and PNP) and the drive transformer L2 form a self-oscillating circuit of a half bridge. In this embodiment, the driving transformer L2 drives the base of the transistor pair and is also a compensation transformer. The main transformer L1 is a 1:1 signal coupling transformer, and the secondary of the main transformer is a rectifying circuit.

The circuit works as follows:

When the current signal is connected to the Π+ and Π- terminals, the resistors R101 and R102 form a DC bias for the transistor pair Q100. The capacitors C104 and C105 form a path relative to the starting moment, and the driving transformer L2 does not instantaneously due to the coil end voltage. The equilibrium relationship always has a current flowing in a direction that is undefined in advance. Assume that the current flows from pin 1 to pin 2. Then there is a current flowing through pins 1 and 2 of L2, flowing through pins 4 and 5 of Q100, flowing through pins 1 and 3 of D101, and returning to pin 1 of L2 to form a loop. At this time, the PNP tube of Q100 is turned on, causing the current to flow from Ii+ through capacitor C104, flowing through pins 1 and 2 of main transformer L1, flowing through pins 3 and 2 of drive transformer L2, and flowing back through pins 4 and 3 of Q100. Ii - forms a loop that completes the positive chopping of the DC signal.

Due to the relationship of the transformer with the same name, the current flows through the 3 and 2 pins for the drive transformer L2 and the electric flow growth trend causes the current flowing through the 4 and 5 pins of the Q100 to increase, further accelerating the current flowing through the pins 1 and 2 of the L1. The positive feedback that forms the current also causes the core of the drive transformer L2 to quickly reach saturation. After that, the voltage of the storage coil of the transformer L2 is reversed, and the electrical flow of the two circuits is reduced. The current flowing through the driving transformer L2 is reduced, causing the driving transformer L2 to invert the base-to-base driving voltage of the triode, and at the same time causing the current to be inverted. When the inverting voltage reaches a certain value, the NPN tube is turned on, and the PNP tube is turned off. The two loop currents are inverted. In the same way, the reverse chopping of the DC signal is completed. The forward and reverse chopping signals are coupled via the L1 transformer After secondary rectification, it is output by Io+ and Io-. In this embodiment, the lead taps of the secondary coil are taken out by the driving transformer L2 (the coils of 1 to 2 are secondary, and the coils of 2 to 3 are primary) penetrate the toroidal core of the main transformer, in order to compensate the secondary lead tap of the transformer. The connection after passing through H is convenient and stable. After the secondary lead tap H passes through the core of the main transformer and is wound (see Figure 7), it is then compensated by the 3 pin of D101. The direction of penetration should increase the output current to If the direction is wrong, the output signal will be reduced. This compensation is compensated proportionally to the change in the input signal and does not affect the linearity of the signal isolated transmission. The compensation amount is calculated as follows:

For example, the ratio of the turns of the main transformer is 1:1, and the distortion of the current signal in the main transformer is 0.5%, that is, the output of the signal is only 99.5%, so the theoretical compensation for the signal should be 0. 5%. Assuming that the input is 20 mA and the output is 19.900 mA, the relative compensation ratio is calculated as: (20- 19.900) /20=1/200, then the compensation transformer coil ratio is 1:200. Connect the primary of the compensation transformer in series to the primary of the main transformer, and then the secondary of the compensation transformer penetrates the toroidal core of the main transformer and then the 3 pin of the D101, which increases the magnetic field strength of the main transformer by 200 times. The isolated transmission of the signal is one-hundredth of a 5% compensation, which improves the accuracy of the passive signal isolator.

As shown in FIG. 2, in this embodiment, the secondary of the driving transformer does not penetrate the core of the main transformer, and an isolated compensation transformer L3 is added, and the primary and secondary pins of the compensation transformer L3 are connected in series to the main transformer L1 and the drive. Between the primary of the transformer L2, one end of the secondary of the compensation transformer L3 is connected to the toroidal core of the main transformer and connected to the other end of the secondary transformer to form a compensation loop. The calculation of the coil ratio of the compensation transformer L3 is compared with the above-mentioned embodiment of FIG. the same. As shown in FIG. 3, this embodiment is basically the same as the embodiment of FIG. 2, except that the compensation transformer adopts an autotransformer, and the primary and the second legs of the transformer L3 are serially connected to the primary circuit of the main transformer, and the secondary three legs are worn. The toroidal core of the main transformer is connected to the secondary 2 pin to form a loop for compensation.

As shown in FIG. 4, in this embodiment, the secondary of the driving transformer does not penetrate the core of the main transformer, and an isolated compensation transformer L3 is added to compensate the secondary connection of the primary of the transformer L3 and the main transformer, and the compensation transformer L3 One end of the secondary connection leads through the main transformer toroidal core and is connected to the other end of the compensation transformer secondary to form a compensation loop.

As shown in FIG. 5, this embodiment is basically the same as the embodiment of FIG. 4, except that the compensation transformer adopts an autotransformer, and the primary and secondary legs of the transformer L3 are serially connected to the secondary circuit of the main transformer, and the secondary 3 legs are The toroidal core passing through the main transformer is connected to the secondary pin 2 to form a loop for compensation.

As shown in Fig. 6, in this embodiment, a winding with a smaller number of turns is added to the main transformer, and the secondary of the driving transformer L2 is connected in series with the windings 5 and 6 of the winding, and the 6th leg of the winding is connected to the 3 pin of the D101. The additional winding coil turns ratio is derived from the magnitude of the error required to compensate, and the compensation transformer turns ratio is calculated as described above.

Claims

Rights request

A signal compensation method for a passive signal isolator, characterized in that: a compensation transformer is added in the passive signal isolator circuit, and the primary of the compensation transformer is connected in series with the primary or secondary of the main transformer in the circuit to compensate One end of the transformer secondary is connected to the lead wire so as to increase the direction of the output current through the toroidal core of the main transformer and then connected according to the function of the compensation transformer; the ratio of the turns of the primary and secondary coils of the compensation transformer is determined by the error of the required compensation .

2. The signal compensation method for a passive signal isolator according to claim 1, wherein: the driving transformer in the passive signal isolator circuit is used as a compensation transformer, and the primary of the main transformer is connected in series with the driving transformer, and the driving transformer is driven. One end of the stage is connected to the toroidal core of the main transformer and then connected to the half-bridge self-excited oscillation circuit.

3. The signal compensation method for a passive signal isolator according to claim 1, wherein: the primary of the compensation transformer is connected in series between the main transformer and the primary of the drive transformer, and one end of the compensation transformer secondary is connected to the lead wire. After passing through the toroidal core of the main transformer, it is connected to the other end of the compensation transformer secondary.

4. The signal compensation method for a passive signal isolator according to claim 1, wherein: the primary of the compensation transformer is connected in series with the secondary of the main transformer, and one end of the compensation transformer secondary is connected through the main transformer ring. The core is then connected to the other end of the compensation transformer secondary.

The signal compensation method for a passive signal isolator according to any one of claims 1 to 4, characterized in that the connection of the secondary of the compensation transformer after passing through the toroidal core of the main transformer is convenient and stable. The secondary of the compensation transformer passes through the main transformer core and is wound and then connected Pick up. .

6. A signal compensation method for a passive signal isolator, characterized in that: a winding is added to a main transformer in a passive signal isolator circuit, and a secondary of the driving transformer in the passive signal isolator circuit and the additional winding After being connected in series, it is connected to the half-bridge self-oscillating circuit, and the turns ratio of the additional winding coil is obtained by the magnitude of the required compensation.