JPS5923094B2 - Metamorphosis device - Google Patents

Description

[Detailed description of the invention] The present invention relates to a transformer using a saturable magnetic core.

In conventional transformation devices that detect direct current or voltage, it is not easy to determine the polarity of the current or voltage to be detected, and the polarity is determined at least at the detection stage of extracting a value proportional to the detected value. I couldn't do it. FIG. 1 is a circuit diagram showing the configuration of a conventional transformation device.

Ti, T2 are saturable magnetic cores, N21, N22 are magnetic cores T
This is the winding wound around T2. Winding N21, N22
If the number of turns of is indicated by N21 and N22 with the same symbol, then N21■
It is N22. In addition, the primary winding Nll2 through which the detected current flows
N12 is also NlllN12. Windings N21 and N22 are connected in anti-series, and bridge-connected diodes D1~
It is excited by the AC power supply VAC via D4. Winding N
In order to detect the current flowing through 21 and N22, a resistor RS is connected in parallel with the diodes D1 and D2, and the voltage across the resistor RS is output. A current source 51, which is the object to be detected and which flows a primary current, is connected to the windings N, 1, and N12.
Output V. is the voltage at the diodes D1 and D2 no matter what direction the current flows in the windings N41, N, and 2, so the direction cannot be determined from this. In order to know the direction of the current, it is also possible to wind another winding around each magnetic core Tl and T2 and detect the polarity from the induced voltage, but this is not practical as it would be complicated. .

Note that FIG. 2 shows the relationship between the voltage VAC of the AC power supply VAC and the current iAc of the circuit shown in FIG. 1. Voltage VAC and current iAc have a square wave shape. The current 1AC is proportional to the current 1L flowing through the winding Nl,,N,, and
As shown in FIG. 2, the voltage AC has a relationship such that the rising edge point P of the current 1AC moves on a line segment 0D. However, point O indicates the midpoint of AB. In addition, the magnetic cores Tl and T2 are
It is used in a restrained magnetization state, and the current flowing between the primary and secondary windings satisfies the equal ampere-turn law on the unsaturated magnetic core side, while the other magnetic core is in a saturated state.
SUMMARY OF THE INVENTION An object of the present invention is to provide a transformer capable of simultaneously detecting the polarity when detecting the current or voltage of a target to be detected with a value proportional to the current or voltage.

Embodiments of the invention will be described below with reference to the figures.

FIG. 3 shows a circuit diagram of the transformer of the present invention. VS in the diagram
1 is a DC power supply, and Q and Q4 are transistors consisting of semiconductor switches or power amplifiers, which are bridge-connected. R5 and R6 are resistors connected to the emitters of the transistors Q3 and Q4, and differentially amplify the voltages D, , VD2 across the resistors to provide the output of the device. 0P,
is a differential amplifier driven by positive and negative power supplies (not shown), which amplifies and outputs the voltage difference between the voltages D, D2 of the resistors R5 and R6.

T is a saturable magnetic core with winding N,.

The winding N1 is connected to the current source SI to flow the current IL or IL2 to be detected, and when it is composed of an annular magnetic core, it is composed of one turn or several turns passing through the window. However, the number of turns may be increased when the current flowing through the winding N1 is large. The magnetic core T further carries a current 1 proportional to the current ILl or IL2. Winding N2 and comparator C for taking out
Control windings N, , N4 that serve as inputs for OMPl and COMP2
has. Here, the number of turns of the winding N, is sufficiently smaller than the number of turns of the winding N2. That is, the magnetic core T is configured to operate in a magnetized state determined by the impedance on the winding N1 side and the impedance on the winding N2 side. Note that L indicated by a dotted line is a reactor connected in series to the winding N. COMP
l, COMP2 is a comparator, which alternately turns on the transistors Q, ~Q4 by introducing the outputs of the control windings N, , N4, thereby exciting the winding N, alternately in different directions. be. ZDl to ZD4 are Zener diodes, and D1 to D4 are feedback diodes. In this configuration, no current is supplied from the current source SI, the magnetic core T is in the unsaturated region, the comparator COMPl outputs zero, and the comparator COMP2 saturates the output to positive (+S1). shall be.

Note that each of the windings N1 to N4 of the magnetic core T starts winding on the side marked with a black circle in the figure. Comparator COMPl, COMP
When the transistors Q, Q3 are turned on by the output of 2, a voltage with a positive black circle mark is applied to the winding N2, a positive induced voltage is generated in the winding N3, and a negative induced voltage is generated in the winding N4. , the voltages of these windings N3, N4 are determined by the comparators COMPl, COM
Since positive feedback is provided so that P2 is set to zero and positive voltage, respectively, transistors Q2 and Q3 are held on, respectively. During this time, the exciting current 1,0 of the magnetic core T is the winding N2,
It is supplied from the power supply VS1 via the reactor L and resistor R5. Eventually, when the magnetic core T reaches a saturation value of magnetic flux +φs, the impedance of the winding N2 decreases rapidly, and the output voltage induced in the windings N3 and N4 also disappears, and at the same time, the impedance of the winding N2 decreases due to the reactance of the winding N2. Due to the release of energy, winding N2 induces a voltage in the opposite direction to the voltage that was applied. This voltage also generates a voltage of opposite polarity to the previous one in the windings N3 and N4. The voltages of the windings N3 and N4 are positively fed back to the inputs of the comparators COMP1 and COMP2, and when the voltages exceed the respective thresholds, the voltages of the comparators COMP1 and
COMP2 each inverts the output and transistor Q
1, turn on Q4. A voltage with a polarity opposite to that before is applied to the winding N2, and the magnetic flux of the magnetic core T is reversed from the saturation value +φs and begins to be excited in the direction of the magnetic flux -φs. During this period, the excitation current IrO is supplied to the transistor Q1 by the DC power supply VSl.
, reactor L1 winding N2, transistor Q4 and resistor R6, and the comparators COMP1 and COMP2 are respectively zero and positive, which are opposite to each other. When the magnetic flux of the magnetic core T reaches the negative saturation value -φs, the polarity is reversed by the same action as if it had reached the saturation value +φS, and it is excited in the direction of the saturation value +φs.
MP2, transistor (Ql, Q4), (Q2, Q3)
, the magnetic core T and the winding N2, the waveform becomes as shown by the dotted lines in FIG. 6b, and self-oscillation occurs. Note that the reactor L is such that the magnetic core T is saturated and the comparator COMPl,C
This is inserted in order to suppress over-excitation due to the current flowing through the winding N2 during the switching period until the polarity of excitation is reversed by the output of OMP2. If there was no reactor L, the saturation of the magnetic core T would cause a considerable current to flow through the resistance R.
5 or R6 and output. Make something momentary but big. This means that even though the current 1L or IL2 of the object to be detected is zero, the output V. does not become zero, which is not desirable. Next, as shown in FIG. 3, a case will be described in which a current 1L1 flows from the current source SI.

When the outputs of the comparators COMPl and COMP2 switch from positive to zero or from zero to positive, the magnetic flux φ of the magnetic core T becomes a negative saturation value -φS
It begins to change toward a more positive saturation value +φs.

During this time, since the magnetic core T is of course unsaturated, the windings N,
An induced current flows through the secondary winding N2 so as to cancel the magnetomotive force caused by the current 1L flowing through the secondary winding N2. Current 1L1 is the winding N
1 flows out from the beginning of the winding, so a current 1 is induced in the winding N2. flows from the beginning of the winding, and between them ILl×N
, =IOXN2, which follows the law of equal ampere-turns, and a current proportional to the current 1L flows through the winding N2. During this time, the winding N2 has VSL-2VES (collector-emitter saturation voltage of transistors Q2 and Q3) - V
A voltage Dl (+IOXRs) is applied, and it takes longer to reach saturation because the voltage is lower than when there is no current 1L1. When the magnetic flux of the magnetic core T reaches +φs, the outputs of the comparators COMP1 and COMP2 are switched to the opposite polarity from the previous polarity due to the positive feedback action by the windings N3 and N4, but as a result, the magnetic flux φ changes from +φs to 1φs. On the other hand, the magnetic core T maintains an unsaturated state. Therefore, the winding N2 has the same polarity as before, and has approximately the same current 1. will flow. During this time, the current is 1. flows through a circuit consisting of resistor R6, transistor Q, winding N2, reactor L, and transistor Q1. Transistors Q4, Ql when switching
A voltage of opposite polarity applied to is absorbed by the diodes D4 and Dl. During this time, the voltage applied to winding N2 is S
1+2ES+D2(+R6XiO), and the period until saturation is reached by this voltage is shorter than when the current 1L1 is zero because the voltage is higher. In the above manner, comparator C
While the outputs of OMPl and COMP2 are switched to zero and positive, respectively, voltages proportional to the primary current are obtained as voltages Dl and VD2 from both ends of the resistor R5 or R6. The amplifier 0P1 differentially amplifies the detection voltages VDl and D2 obtained by switching the comparators COMPl and COMP2, and outputs V. If the amplification degree of amplifier 0P is 1, then when transistors Q2 and Q3 are on, VO=VDltransistor Q
When Q4 is on, VO=O-(-VD2)=D2. If R,=R6, when the detected current 1L1 is flowing, a voltage of VO=VDl=D2 is obtained. The above operation is shown in FIG. 6, where a indicates the current (current in the winding N1) ILl, and b indicates the output voltage e of the comparator COMP2.
, and c represents the voltage N2 applied to the winding N2.

Further, d represents the voltage VL of the reactor L, e represents the magnetic flux φ of the magnetic core T, and f represents the voltage across the resistor R5 or R6, that is, the output V. (or current 1). In both cases, time is shown on the horizontal axis. Note that the dotted lines in b-e each indicate the case where the current 1L0=O. Also, A and A5 indicated by dotted lines in f indicate the currents when there is no reactor L and the current is 1L, +0, and when IL, =O, respectively. Next, a case will be described in which the polarity of the current 1L flowing through the winding N is reversed.

In this case, the current is 1 when viewed from the winding N2 side. The polarity of is reversed. That is, since the polarity of the current flowing through the resistors R, R6 is different from the above, the output V. is also reversed. Therefore, the output V.
The direction of the primary side currents 1L1 and iL2 can also be detected by looking at the currents 1L1 and iL2. That is, in FIG. 3, when the current 1L from the current source SI flows in the direction of the arrow, IL2XN
, = IOXN2, the current 1 that satisfies the equal ampere-turn law
0 flows through winding N2 in the opposite direction to the arrow shown. When transistors Q2 and Q3 are on, this current 10 is V
Sl - resistor R, one transistor Q3 (or diode D
3) Take the path: - reactor L, winding N2 - transistor Q2 (or diode D2) - VS1. Further, when transistors Ql and Q4 are 0N, S1 - transistor Q, - reactor L - winding N2 - transistor Q4
It flows through a path of one resistance R6-VS1. Therefore,
The direction of the current flowing through the resistors R5, R, is exactly opposite to that of the current 1L1, which has the opposite polarity to the current 1L2 from the current source SI. Output of amplifier 0P. is the resistance R,,
Since the voltages Dl and D2 across R6 are differentially amplified,
Its voltage V. is also obtained as exactly the inverted value. In FIG. 3, the outputs of resistors R, , R6 and amplifier 0P1. On the other hand, the case where a voltage appears in the polarity when a plus or minus sign is attached indicates the time when the current 1L1 from the current source SI flows with the polarity. The case where these polarities are opposite to those shown in the drawing corresponds to the case where the current flows from the current source SI with the polarity of the current 1L2. In either case, transistor Q2
, Q3 are on, and by the resistor R6 when the transistors Ql and Q4 are on. The situation during this time is shown in FIG. In the left half of Figure 7, a current of 1 is applied to the winding N1 from the end of the winding N1.
When L, flows in, the case where current 1L2 flows into winding N, from the beginning of winding N, in the right half is shown. As for the voltage N, as shown in FIG. 7, the oversaturation period that occurs when the polarity is switched is ignored. Note that in the above explanation, the excitation current is ignored; the reason is that the current 1. This is because the excitation current is considered to be so small that it can be ignored in practice. Also, the comparator COMP
This is because, if the input impedance of L and COMP2 is also sufficiently high, the value of the current flowing through the windings N3 and N4 converted into the winding N2 is so small that it can be ignored in practical terms. In addition, in the configuration of FIG. 3, the voltage drop across the resistors R3 and R4 in relation to the base current that drives the transistors Q3 and Q4 becomes 1 if the current amplification factor β of the transistors Q3 and Q4 is selected to be large. can be kept to a small value that does not pose a problem in practice. In addition, in FIG. 6, the output is 1 during the polarity switching time δt. If the ripple of ΔIO is suppressed to be ΔIO (converted into a current value, the value of the reactor L that suppresses the ripple ΔIO during this period is theoretically expressed as approximately V′EXδt/ΔIO). however,
'e represents the excitation voltage, which changes due to the voltage drop caused by the current in the resistors R, . In this way, by inserting the reactor L, the output V.

This makes it possible to suppress the ripple to a value that poses no problem in practice. As is clear from the above description, the transformer having the configuration shown in FIG. 3 can detect the polarity of the load current and can also detect the AC current.

Furthermore, since the present invention is constructed with a single magnetic core, the device can be simplified. Further, since the present invention can be driven with only a single DC power source, the device is simple and no rectifying means is required to detect DC current, which is highly effective. Note that by using a reactor, output ripple can be reduced, and its practical value is high. The above is a description of the transformer of the first embodiment. The number of turns of the primary winding N1 is increased, and a high impedance element such as a reactor or series resistance is connected as a load to the winding N1. If the currents 1L1 and 1L2 are made constant currents,
It goes without saying that the operation is similar to that of the conventional transformation device, the effect is also the same as that of the above embodiment, and the device can be simplified.

Another embodiment according to the invention is shown in FIG.

In FIG. 4, only a winding N3 is provided for detection, and is connected to the positive and negative input terminals of comparators COMP1 and COMP2 to provide the same function as the circuit shown in FIG. 3. According to this circuit, only the winding N is required, so the configuration is simpler than that shown in FIG. A similar effect can also be obtained by providing a detection winding in the ripple removal reactor L and feeding it back to the comparator. FIG. 5 shows another embodiment of the present invention, showing a polarity detection type configuration.

If the current 1L1 from the current source SI flows out from the beginning of the winding N1 without changing its polarity, the current 1 in the winding N2. flows from the beginning of the winding, and this polarity does not change even if the polarity of the voltage changes. In this case, the current flowing through transistors Q, ,Q2 is
When turned off, DC power supply S1, resistor R3, diode D
1. Current ILl flows through reactor L1 winding N2, diode D2, and DC power supply VSl, so current ILl can be detected by detecting the voltage across resistor R3. In this way, since the polarity of the load current does not change, unlike the circuit shown in FIG.
D4 is omitted. In addition, in Fig. 5, the windings N,
By simply applying the output of the comparator COMP1 to the negative input terminal of the comparator COMP2, the same function as the embodiments of FIGS. 3 and 4 is obtained. FIG. 8 shows yet another embodiment of the invention.

Assuming that switches SWl to SW4 are all on the contact b side as shown in the figure, the voltage induced in winding N3 is
By comparing with OMP1, ``transistor Q2 repeats on and off. During this time, the thyristor CR, continues to be on, and the current IL, from the current source ST flows into the winding N1 with the polarity shown, so that the current flowing through the winding N2 is changed by turning on and off the transistor Q2. -Q2-N2
-L-CR, -R, -VSl path or N2-L-C
Since it flows through either of the paths Rl-R and -D4-N2, its value can be known from the resistance R. When switches SWl to SW4 are tilted to side a, the current is 1L.
When the direction of 1 is reversed, transistor Q2 is changed to transistor Q, and thyristor CRl is changed to thyristor C
It may be considered by replacing R2 or resistor R5 with R6. Note that the resistor RL connected in parallel to the reactor L is a damping resistor, and is used to offset the effect of the reactor L on the stray capacitance. In this way, the circuit shown in FIG.
,, CR2 is used, which has the effect of making the switching means easier. Note that if only unipolarity is considered, the circuit can be further simplified. For example, if you want to detect the current 1L1 shown in the figure with the circuit of winding N2, thyristor CRl
is no longer needed, and it is sufficient to directly connect this part, and furthermore, transistor Q1, thyristor CR2, diode D3
is also no longer needed. In the embodiments of the present invention described above, the voltage is differentially taken out from both ends of the two resistors provided on each leg of the bridge-coupled transistor as the output of the transformer. It is also possible to insert a resistor in series with the resistor and output the voltage across the resistor.

In this case, not only is the device simple, but the accuracy is also increased because the base current of the switching transistor does not flow through the resistor. Furthermore, even if each of the two sets of upper and lower transistors constituting the bridge is configured with a power amplifier, that is, two sets of power amplifiers are used, the effect is the same as in the above embodiment. As described above, according to the present invention, the polarity of the current of the object to be detected can be known, the current and voltage can also be detected, and the device can be simplified because it can be driven with only a single DC power supply. , its practical value is high.

[Brief explanation of the drawing]

FIG. 1 shows an example of the configuration of a conventional transformation device, FIG. 2 is a diagram explaining the operation of the circuit shown in FIG. 1, and FIGS. 6 and 7 are waveform diagrams showing the operating state of the circuit of FIG. 3.

Claims (1)

[Claims] 1. A DC power supply, connected in parallel between both ends of the DC power supply,
two series circuits each having two switching elements and a resistance element sequentially connected in series from one pole to the other pole of the DC power supply, a saturable magnetic core, and each of the switching elements constituting each of the series circuits; An excitation winding connected between the series connection points and wound around the saturable magnetic core, a control winding wound around the saturable magnetic core, and a current to be detected is applied and wound around the saturable magnetic core. a saturable transformer comprising a primary winding; one of the switching elements in each series circuit is turned on and the other is turned off depending on the polarity of the output of the control winding; A transformer comprising: a comparator that connects the excitation winding to both ends of the DC power source via an element; and means for inputting the voltages across the resistive elements and amplifying and outputting the difference voltage. 2. The transformation device according to claim 1, wherein at least one of the switching elements is a transistor. 3. The transformation device according to claim 1, wherein at least one of the switching elements is a diode. 4. The transformation device according to claim 1, wherein at least one of the switching elements is a thyristor.