JPH02245806A - Power source synchronizing circuit - Google Patents

Abstract

PURPOSE:To prevent the damage of a load and the abnormal action of a device by means of an abnormal output due to the deviation of the rise and fall of both voltages by judging the voltage state of positive and negative voltages and controlling the rise fall timing of the ON/OFF of both positive and negative voltages. CONSTITUTION:It is judged whether a differential voltage 2V between the posi tive and negative input voltages +V and -V by resistances R1 and R2 and a Zener diode ZD1, and the ON/OFF of enhancement MOSFET TR1 and TR2 for deciding the rise and the fall of the ON/OFF of the positive and negative output voltages +Vs and -Vs are decided in accordance with the decided result. In the load circuit and the device using the positive and negative voltages, the damage given to the load by the occurrence of the abnormal output of the abnormal voltage and the abnormal current due to the deviation of the rise and the fall of both voltages, and the abnormal action as the device can be prevented.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a power supply synchronization circuit for a load circuit, such as a current sensor, which uses both positive and negative voltages as its power supply, and particularly relates to a power supply synchronization circuit for a load circuit such as a current sensor that uses both positive and negative voltages as its power supply. This relates to a power synchronization circuit that synchronizes the falling edge of the power supply.

[Prior Art] Conventionally, in controlling equipment on a factory production line, many sensors are used to detect the status of each equipment. A common large-capacity DC power supply is prepared as a power source for these sensors, and each sensor obtains the voltage necessary for its operation from this DC power supply, and the on/off of the voltage supply is controlled by a manual switch. are doing.

If the sensor requires both positive and negative voltages, for example, as shown in FIG. Both positive and negative voltages are sent to sensor 3 via switch 2.
to be applied. That is, the ground potential GND is fixedly applied to the sensor 3, and the ÷V and -V voltages are applied to the sensor 3 via the double-throw switch 2, which is turned on and off at the same time.

In this case, depending on the shape of the switch 2, only one voltage (÷V) is applied to the sensor 3 first, as shown in FIG.
The other voltage (-V) may be applied with a delay. Further, even if one voltage generating portion of the positive and negative DC power supply 1 is out of order, only the voltage of the other voltage may be applied to the sensor.

A similar problem can occur not only on a factory production line, but also when a power switch is placed between the DC power source and the device, or when one power source simply breaks down. .

[Problem to be solved by the invention] In such a case, a circuit designed to settle into a certain steady state by feedback using a feedback circuit etc. is installed in a device such as a sensor to which both positive and negative voltages are applied. In some cases, if only one voltage is applied, the device will deviate from the steady state, and there is a risk that the device will operate abnormally or generate abnormal output such as abnormal voltage or current. In addition, if an amplifier section with an emitter follower at the final stage is installed in the device, this amplifier section will generate abnormal output such as abnormal voltage or current, so the output of this amplifier section will be used as the output of the device. If you take it out and drive some kind of load, there is a risk that the load will be damaged.

SUMMARY OF THE INVENTION Therefore, in order to eliminate the drawbacks of the conventional example, it is an object of the present invention to supply these positive and negative voltages to the required equipment when powered from the positive and negative DC power sources, and when powered from only one of the power sources. An object of the present invention is to provide a power synchronization circuit appropriately configured so as not to supply one of the voltages to a device.

[Means for Solving the Problems] In order to achieve such an object, the present invention is connected to a power source that supplies positive voltage and negative voltage, and the voltage difference between the positive voltage and the negative voltage is a predetermined voltage. A determination means for determining whether or not the value exceeds a value, and a control means for determining whether to simultaneously output a positive voltage and a negative voltage from the power supply or to cut off the same at the same time in response to the determination output from the determination means, The present invention is characterized in that a positive voltage and a negative voltage whose rise and fall are synchronized with each other are taken out from the control means.

[Function] According to the present invention, the voltage states of both the positive and negative voltages are determined, and the timing of turning on, turning off, and falling of both the positive and negative voltages is controlled according to the determination results.
In load circuits and equipment that use both positive and negative voltages as a power source, abnormal voltage caused by a difference in the rise and fall of both types of voltage.

It is possible to prevent damage to the load due to the occurrence of abnormal output such as abnormal current, and to prevent abnormal operation of the device.

[Example] Hereinafter, an example of the present invention will be described in detail with reference to the drawings.

An embodiment of the power supply synchronization circuit of the present invention is shown in FIG.

In the synchronization circuit shown in FIG. 1, a resistor R1, a Zener diode ZD,
A series circuit consisting of the resistor R2 and the resistor R2 is connected. Enhancement type P is connected between the input terminal ◆V and the output voltage medium VS.
Connect channel MO5FET TR+ and input terminal -■
An enhancement type N-channel MO5FET TR2 is connected between the output voltage -vs and the output voltage -vs. MOSFET T
R.

The gate of is connected to the connection point between the resistor R and the Zener diode zOI. The gate of MOSFET TR2 is connected to the connection point between resistor R2 and Zener diode zD.

The synchronization circuit shown in FIG. 1 is connected to a positive/negative DC power supply 1 and a load circuit 3 such as a sensor, as shown in FIG. That is, in FIG. 2, 10 is the synchronization circuit shown in FIG. 1, which is supplied with ◆V, GND, and -V from the positive and negative DC power supplies 1, and synchronizes the rise and fall of these positive and negative voltages. , which eliminates the drawbacks of the conventional example. That is, if one of the positive and negative DC power supplies 1 fails, or if only one of the positive and negative voltages is applied due to a delay in turning on and off the switch, no voltage is applied to the required equipment 3. Only when both voltages of the positive and negative DC power supplies 1 are supplied together, the positive and negative DC voltages are applied to the required equipment 3.

The operation of the circuit shown in FIG. 1 will be explained when connected as shown in FIG. 2.

Here, if both voltages +V and 12 are applied to the circuit 10, the 2V potential difference between the two will cause the Zener diode 201 to
When the Zener voltage v0 of
The bias voltage is not forward biased between the gate and source of TR6 and TR2, so these MO
5FETs R6 and TR2 are not conductive.

Even when only one voltage is applied, the Zener diode ZD+ does not become conductive, so MO5FETTR+
And between the gate and source of TR2, the bias voltage is not forward biased, so the MOSFET
TR and Tlh are not conductive.

On the other hand, when both +V and -V voltages are applied to the circuit IO, and the potential difference 2V between them is greater than V, the Zener diode ZDI becomes conductive, and the MOSFET
The bias voltage becomes forward bias between the gate and source of TR+ and TR2, and these MOSFETs
TR+ and TR2 conduct. Here, klO5FE
By making the drain voltage-current characteristics of TTR+ and TR2 the same, ◆VS and -VS can be changed as follows.

When both positive and negative voltages ÷ V and -V are cut off at the same time,
Since the drain voltage-current characteristics of MOSFETs TR+ and TR2 are the same, the potential difference 2V between them is Vzd.
◆vs and -vS become smaller as they approach , and are turned off at the same time after falling below Vzd.

If only one voltage is turned off, the Zener diode o+ becomes non-conducting at the time when the one voltage turns off, and MOSFETs TR+ and TR2
The bias voltage between the gate and source of is no longer in a forward bias state. Here, MO5FETTR, and T
Since the drain voltage-current characteristics of R2 are the same, ◆
vs and -VS are similarly small.

In the embodiment shown in FIG. 1, the resistors R3 and R2 and the Zener diode ZD are used to determine whether the voltage difference 2v between the positive and negative input terminals divided by V and -V is greater than a predetermined threshold voltage (for example, V2d). According to the judgment result, both positive and negative output voltages +v5 and -vS are turned on.

Enhancement type -05FET TR+ and Tlh are turned on to determine the rise and fall of OFF.

Define off.

In this way, ・Difference voltage 2 between both positive and negative input terminals +V and 1■
means for determining whether v is greater than a predetermined threshold voltage;
And, depending on the judgment result, both the positive and negative output voltages ÷V, and the on/off rise of -vs.

The control means for determining the fall is the resistor R1, 112.
and Zener diode ZD, , and MOSFET
The third example is not limited to TR+ and TR2 examples.
It is also possible to configure as shown in FIGS.

In the example of FIG. 3, photocouplers PC and PC2 are used, and the determination means is constituted by a series circuit of a photodiode D1, a resistor R1, and a photodiode D2. The control means is constituted by phototransistors PT and PT receiving respective output lights from photodiodes D1 and D2, and these phototransistors PTI and P
T2, respectively, between the voltage +V and the voltage ν3 and 1■
and -vs.

In the example of FIG. 4, photoMOS relays PM and P
N2 is used, and the photodiode D is used as the judgment means.

It consists of a series circuit of a resistor R4 and a photodiode D4. The control means includes photodiodes D3 and D.
A photoMOS transistor P receives each output light from 4.
The photo-VOS transistors PT and PT4 are arranged between voltages ÷V and +VS and between 1 and -v5, respectively.

In the example shown in FIG. 5, the above judgment means is a mechanical relay nY.
The coil CL is configured such that two normally open contacts a1 and R2 are closed when a predetermined voltage of 2V is applied to the coil CL. These contacts at and R2 constitute the control means, and the contacts a and a.

, respectively, between the voltages ◆V and ◆VS and between -V and -
Place it between VS.

The synchronization circuit of the embodiment described above can be applied to, for example, a power supply circuit of a current sensor. Recently, as the performance of various control devices such as NG servos that use current sensors has improved, the performance required of current sensors has become higher and higher. For this reason, the power sensor method used is one that is easy to achieve high performance, that is, the magnetic flux generated by the current to be measured is detected as a voltage by a Hall element, and a secondary current is passed so that this voltage becomes zero. A method of canceling out the magnetic flux generated by the magnetic flux and extracting this secondary current as a measurement value has come to be used.

For example, an example of application to a current sensor as shown in FIG. 6 will be explained. Here, for a current sensor composed of a secondary coil L2, a core CR, a pole element [IE, an operational amplifier, a buffer circuit ^2, a measuring resistor R1, and a stabilized power supply circuit pw, the positive and negative according to the present invention are The output voltage ◆vs and - from the synchronization circuit IO for the rise and fall of both voltages
Supplies vs and GND.

Here, whether or not to provide the stabilizing power supply circuit PW may be determined depending on the desired accuracy of the current sensor.

FIG. 7 is a circuit diagram showing a specific example of the buffer circuit A2 together with a coil L2 and a measuring resistor R.

Buffer circuit A2 includes resistors R6 and R6 and diode D.
Series connection with s and D6 and PNP transistor TR
The output of the operational amplifier ^1 is supplied to the connection point with the diodes D and D6, and the bases of the transistors TR3 and TR4 are connected to the resistor R6 and the diode D, respectively. and the connection point between resistor R6 and diode D6. The point where the emitters of both transistors Tn3 and TR are connected is connected to the coil L2.

In FIG. 7, when the circuit 1O of the present invention is not provided, for example, the rise points of both the positive and negative voltages are shifted, and the +
When only vc is on and -vc is off, base current ib flows through transistor TR3, which flows through the secondary coil, and the sum of collector current ic and base current ib (hr,
+1) ib flows. Here, hf is the current amplification factor when the emitter is grounded. At this time, magnetic flux is generated within the secondary coil 2, and the core CR is magnetized. After that, even if -vc is turned on and the magnetic flux in the secondary coil L2 disappears, a residual magnetic field remains in the core CR, so the Hall element HE detects this residual magnetic field, and as a result, the zero point of the current sensor However, as shown in Figure 6, in the current sensor equipped with the synchronization circuit IO of the present invention, both the positive and negative voltages always rise and fall in synchronization. Therefore, the current sensor will not indicate an incorrect current value.

[Effects of the Invention] According to the present invention, the voltage states of both the positive and negative voltages are determined, and the timing of the on/off rise and fall of both the positive and negative voltages is controlled according to the determination results.
In load circuits and equipment that use both positive and negative voltages as a power supply, it is possible to prevent damage to the load due to the occurrence of abnormal outputs such as abnormal voltages and abnormal currents due to deviations in the rise and fall of both voltages, and to prevent abnormalities in the equipment. You can prevent the action.

[Brief explanation of drawings]

Fig. 1 is a circuit diagram showing one embodiment of the present invention, Fig. 2 is a block diagram showing an example of use of the circuit of the present invention, and Figs. 3 to 5 are circuit diagrams showing three other embodiments of the present invention. , Fig. 6 is a block diagram showing a configuration example of a current sensor to which the present invention is applied, Fig. 7 is an explanatory diagram of operation when only ÷ VC is on, Fig. 8 is a circuit diagram showing a conventional example, and Fig. 9 is FIG. 2 is an explanatory diagram of an example of voltage application to a conventional sensor. 1...Positive/negative DC power supply, 2...Switch, 3...Sensor, lO...Synchronization circuit, R3-R6...Resistor, R,...Measurement resistance, zDl...Zener Diode, 0, ~04...Photodiode, D,, D6...Diode, TR,, TR,...MOSFET. PC,, PC,...Photocoupler, PT, ,PT,...Phototransistor, PMI,
PH1...Photo MO5 relay PT,, PT,...
Photo MO5FET. RY...Relay, CL...Relay coil, al+a2...Normally open contact, L2...Secondary coil, CR...Core, Column 0 time river diagram Figure 1 Water flow, diagram Figure 1 circuit. This example of the 4th crime is shown in Figure 4. Figure 4. Figure 5. Block diagram Fig. 6 + Operation of Vc sword h on θ and sa is also clear diagram Fig. 7

Claims (1)

[Claims] 1) A determining means connected to a power source that supplies positive voltage and negative voltage, and determining whether the voltage difference between the positive voltage and the negative voltage exceeds a predetermined voltage value, and a determination output from the determining means. control means for determining whether to simultaneously output or simultaneously cut off the positive voltage and the negative voltage from the power source in response to the output of the positive voltage and the negative voltage whose rise and fall are synchronized with each other. A power synchronization circuit characterized in that it takes out.