JPS6122363Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a redundant current output device.

In a system that supplies a current signal from a signal source to a demand end, the reliability of the system is sometimes increased by duplicating the signal source. In such a system, when a failure occurs in the signal source on the active side, the signal source on the standby side is switched to continue operation of the system, while the failed signal source is repaired.

When switching from the active side to the standby side due to the occurrence of a failure, the continuity of the current signal value must be maintained. In order to achieve continuity, the standby side must be prepared to output a current that matches the output current of the working side, so the standby side must observe the output current of the working side and adjust its own current accordingly. Output signal needs to be adjusted. Furthermore, since switching from the active side to the standby side is performed by an external device, each signal source must observe whether it is on the active side or on the standby side.

Conventionally, in order to observe such output currents and states, transmission lines for observation signals were required, making the configuration complicated.

An object of the present invention is to provide a redundant current output device with simplified signal wiring.

In this invention, the standby side uses the current output line to obtain the output current observation signal of the active side, and the active and standby sides use their respective current output lines to obtain the status observation signal. be.

Hereinafter, the present invention will be explained in detail with reference to the drawings.
FIG. 1 is a conceptual block diagram of an embodiment of the present invention.
In FIG. 1, reference numerals 1 and 2 are redundant current signal sources, which are controlled by control units 11 and 21, respectively, and generate current signals in accordance with the control units 11 and 21, respectively. The current signal sources 1 and 2 are also combined with current monitors 12 and 22 and state monitors 13 and 23, respectively.

3 is a switching circuit, and 4 is a load provided at the demand end. The output current of either the current signal sources 1 or 2 is applied to the load 4 through the switching circuit 3. The switching circuit 3 includes two interlocking switching switches 31 and 32.
and resistors 33 and 34. The changeover switches 31 and 32 are for connecting one side of the output line of the current signal sources 1 and 2 to the load 4 or one end of the resistor 33, and by being operated in conjunction with each other, it is possible to select either of the current signal sources 1 or 2. When one is connected to the load 4, the other is connected to the resistor 33. The common side output lines of the current signal sources 1 and 2 are connected in common, and this common connection point is led to one end of the resistor 34. The other end of the resistor 34 is commonly connected to the other end of the resistor 33, and this common connection point is led to the other end of the load 4.

With such a configuration, a series circuit of a load 4 and a resistor 33 is connected to one of the current signal sources 1 and 2, and a series circuit of a resistor 33 and a resistor 34 is connected to the other. The side to which the load 4 is connected is the active side, and the side to which the resistor 33 is connected is the standby side.
The value of the resistor 33 is set to be sufficiently larger than the resistance value of the load 4. On the other hand, the value of the resistor 34 is set to an appropriate value smaller than the resistor 33, preferably smaller than the load 4. This resistor 34 is included in both the active side and the standby side.

The operation of the device configured in this way is as follows. Assuming that current signal source 1 is currently on the active side and current signal source 2 is on the standby side, current signal source 1 is sending out an output current, and current signal source 2 has stopped sending out output current. Therefore, a voltage drop proportional to the output current of the current signal source 1 occurs in the resistor 34,
This voltage drop is applied to the current observation device 22 through the output line on the standby side and observed thereby. The input resistance of the current observation device 22 is determined to be sufficiently large so that the resistance 33 does not become a problem. Current observation device 2
The output signal of 2 is given to the control section 21, and the output signal of the control section 2
1, the current is set in accordance with the observed current value. This ensures continuity of the current value when the current signal source 2 is switched to the active side by switching the changeover switches 31 and 32. If the active side and the standby side are reversed from the above, the same thing is done in the current signal source 1.

In other words, the output current on the active side can be observed without requiring a special signal line, and preparations on the standby side can be made based on the observation.

The active and standby states of the current signal sources 1 and 2 are determined by the voltage state of each output line. In other words, when the current signal source 2, which was previously on the active side, is switched to the standby side, the output voltage of the current signal source 2, which attempts to supply a specified current to it, increases due to the increased resistance being loaded. increase This increase in the output voltage is detected by the state monitor 23, and is notified to the control unit 21 by its output signal, and the output current of the current signal source 2 is stopped. When the output current stops, the output voltage also decreases, but the detection operation of the status monitor 23 is provided with hysteresis so that it does not respond to the decrease in the output voltage at this time. The same thing happens in the current signal source 1 when the current signal source 1 is switched from the active side to the standby side.

In this way, the active and standby states can be observed at each current signal source without requiring special signal lines.

An example of the connection relationship between the current signal source 1, current observation device 12, and state observation device 13 in the device shown in FIG.
As shown in the figure. This configuration is similar on the current signal source 2 side. In Figure 2, 1
00 is a power supply, 101 is an output transistor, 1
02 is an error amplifier for transistor control, 103
104 is a resistor for detecting the transistor output current; 104 is a reference voltage source for setting the transistor output current;
5 is a diode, and 106 to 109 are voltage dividing resistors, which constitute the current signal source 1. The output current of the transistor 101 is outputted through the current detection resistor 103 and the diode 105, and is returned to the common line through the load. Voltage dividing circuits consisting of resistors 106, 107 and 108, 109 are provided downstream and upstream of current detection resistor 103, respectively, and the respective divided voltage outputs are input to error amplifier 102. A reference voltage source 104 is provided on the common line side of a voltage divider circuit made up of resistors 106 and 107. The output signal of the error amplifier 102 is applied to the base of the transistor 101 to control the output current of the transistor 101. With this control, the output current of the transistor 101 and the resulting voltage drop across the current detection resistor 103 become equal to the value defined by the reference voltage source 104. Since the voltage of the reference voltage source 104 is set by the control section, the output current of the transistor 101, that is, the current signal of the current signal source 1, is defined by the control section.

The current observation device 12 is constituted by an operational amplifier connected as a voltage follower, and is adapted to detect the voltage of the output line of the current signal source 1. Condition observation device 13
is the voltage of the output line of the current signal source 1 and the voltage of the transistor 1 by the resistors 110 and 111 by the operational amplifier.
01, and the "L" polarity signal of the comparison output is applied to the base of the transistor 101 through the diode 131.

Due to the setting of the voltage division ratio, when the current signal source 1 is on the working side, the divided voltage is higher than the voltage of the output line.
The comparison output of is "H" and is blocked by the diode 131, and has no effect on the transistor 101. On the other hand, current signal source 1
becomes the standby side, the resistance value on the load side becomes extremely large, so that the voltage division ratio of the voltage divider circuit formed by that resistance and the current detection resistor 103 becomes higher than the voltage division ratio by the resistors 110 and 111. As the voltage increases, the comparison output of the state observation device 13 becomes "L" due to a corresponding change in the input voltage. This output signal is applied to the base of the transistor 101 through the diode 131, and is applied to the error amplifier 102.
The transistor is reverse biased by absorbing the control output of the transistor 101, and the transistor 101 is turned off. As a result, the output current of the current signal source 1 is stopped.

After this, the voltage on the output line drops to a certain positive value corresponding to the observed value of the output current on the working side, but this voltage is blocked by diode 105, so the emitter voltage of transistor 101 is zero. ,
Therefore, the output signal of the state observer 13 is maintained at "L". That is, the state observer 13 operates with hysteresis and produces a stable output signal.

As described above, according to the present invention, the standby side uses the current output line to obtain the output current observation signal, and the active side and the standby side use their respective current output lines to obtain the status observation signal. Therefore, a redundant current output device with simplified signal wiring can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a conceptual block diagram of an embodiment of the present invention, and FIG. 2 is a detailed diagram of a part of the above figure. 1, 2... Current signal source, 11, 21... Control unit, 12, 22... Current observation device, 13, 23...
Condition observation device, 3...Switching circuit, 31, 32...Switching switch, 33, 34...Resistor, 4...Load.

Claims (1)

[Scope of utility model registration request] It is an emitsuta follower type transistor circuit,
A current detection resistor in series with the emitter, a diode in series with this resistor in the forward direction of the emitter current, the divided voltage value between the emitter side end of the current detection resistor and the common line, and the diode side end of the current detection resistor. and an error amplifier that controls the transistor according to the difference between the current setting reference potential point and the voltage division value. Two current signal sources, the two wires on the opposite side from the common side of the respective output lines of these current signal sources are connected to one end of the load and one end of the first resistor whose resistance value is larger than this load, and one wire is connected to the other end of the load. a changeover switch that connects the other wire to the first resistor when the other wire is connected to the load; a switching circuit having a second resistor connected to the other end of the first resistor and led to the other end of the load; and a switching circuit provided in pairs with each of the two current signal sources and adapted to the voltage between the respective output lines. a current observation device that observes the current signal on the active side during standby based on the current signal source, and a current observation device that is provided in pairs with the two current signal sources and measures the divided voltage value between the emitter of the transistor and the common line and the voltage between the output line, respectively. A redundant current output device comprising a state observation device that compares the switching state of the switching circuit to determine the switching state of the switching circuit, and uses the resulting output to control the effectiveness of the operation of the transistor.