JPH05191922A - Power source circuit for parallel operation - Google Patents

Abstract

PURPOSE:To enhance the power effects, prevent the mutually interfering action from occurring between both power sources, and improve reliability by detecting the polarities of diodes in a diode OR circuit. CONSTITUTION:When the polarity of a voltage at point A is positive with respect to a voltage at C point, a transistor Q1 becomes conductive by a differential amplifier 8 while the transitors Q2 and Q3 becomes non-conductive. If the output voltage of a first power source is increased to make a zener diode ZD reach the breakdown voltage, a photocoupler PC is illuminated. In other words, a high-voltage disconnecting circuit 12 is activated to prevent the voltage to a charge 3 from being increased abnormally. On the contrary, if the polarity of the voltage at A point is negative with respect to the voltage at C point, the transistor Q3 becomes conductive. Therefore, the photocoupler PC is not illuminated. Thus, it is possible to prevent the mutually interfering action from occurring due to the abnormally high voltage between the power sources without activating the high-voltage disconnecting circuit. In other words, lower-order voltage drop diodes can be adopted as the diodes for the diode OR circuit, thus enhancing the power effects.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a highly reliable parallel operation power supply circuit having high power efficiency.

In an optical fiber transmission route in a national trunk communication network, a high degree of reliability is required for transmission related equipment, especially a power supply device. For this reason, the two power sources, including the working and standby units, have been operated in parallel in the past. However, in order to prevent mutual interference between the two power sources, such as reverse inflow of current, current is supplied to the load via the diode OR circuit. is doing.

As a result, the diode has a large forward voltage drop, and the power consumption of the diode is large.
There is a problem that power efficiency decreases, and if a diode with a small forward voltage drop is used to solve this,
The reverse characteristic is bad in the physical law, and there was a problem that the problem of mutual interference between the two power sources was rekindled.

The physical law referred to here is that if the ideal diode characteristics are hypothesized, and the forward characteristic of the actual semiconductor diode is brought closer to this, the backward characteristic is moved away, and if the backward characteristic is brought closer to this, the forward characteristic becomes. Tends to move away,
It refers to the qualitative principle.

[0005]

2. Description of the Related Art In an optical cable transmission route or the like in a national trunk communication network, a line bundle accommodated therein is enormous, and transmission related equipment, especially a power supply device, is required to have high reliability. In order to meet this demand, naturally a standby power supply is required in addition to the working power supply. However, when the working power supply has an abnormality or a failure, the configuration in which the power supply is switched to the standby power supply may cause a transient phenomenon such as a momentary interruption or an inrush current, and sufficient reliability cannot be expected.

For this reason, conventionally, a structure has been adopted in which two power supplies having the same nominal rating, including the working and spare, are connected in parallel to supply a current to a load. In this case, if two power supplies are directly connected to the load, mutual interference between the two power supplies may occur, such as a large current flowing backward from the higher output voltage to the lower output voltage. Instead, the current is supplied to the load via the diode OR circuit.

The conventional technique will be described below. FIG. 4 is a block diagram of this prior art. In the figure, 1 and 2 are first and second motors that are operated in parallel and have the same nominal ratings.
A power source and a second power source, D1 and D2 are diodes forming an OR circuit, 3 is a load, and the first power source 1 and the second power source 2 are pseudo load resistors 11 and 21, respectively, high voltage cutoff circuits 12 and 22, and low. All or part of the voltage alarm circuits 13 and 23 are incorporated.
A and B are the anode points of the diodes D1 and D2, C is also the cathode point or load connection point, and E is normally grounded at the common potential point.

When the voltage V _C at the load connection point C is, for example, 5 volts (hereinafter referred to as V) and the current consumption of the load 3 is, for example, 5 amps (hereinafter referred to as A), the load current is the first power source. 1 and the second power supply 2 share. If the power supplies 1 and 2 and the diodes D1 and D2 have exactly the same characteristics, the power supplies 1 and 2 equally share 2.5A each. So this is a balanced state. Actually, there is no perfect equilibrium state, so if both current sources 1 and 2 have a current capacity of 5 _A , each power source voltage V _A
And V _B, and the current value determined by the forward voltage drop characteristic of each diode, for example, 1.5 A and 3.5 A, are shared, and there is no difference.

First, the diodes D1 and D2 are connected to the PN
A case of a high reverse breakdown voltage small reverse current diode such as a junction silicon diode will be described. FIG. 5 shows a rectification characteristic diagram of the high reverse breakdown voltage small reverse current diode as described above.

In the figure, both the voltage (V) axis and the current (I) axis have different coordinate scales in the forward direction (F) and the reverse direction (R), and both are scales for convenience of explanation. There is. As shown in the figure, in this type of diode, the reverse breakdown voltage ranges from 100 V to 200 V, and the reverse current is as small as several μA or less. Therefore, the first power supply 1 and the second power supply 2 operate without any mutual interference.

For example, if the second power supply 2 fails and the output voltage V _B drops significantly, the first power supply 1 alone takes the load in the route of the first power supply 1 → D1 → load 3. vice versa,
When the second power supply 2 fails and the output voltage V _B rises significantly, the following occurs.

FIG. 6 shows a time t vs. voltage V change characteristic of each point in the circuit of FIG. 4 in the case of the diode OR circuit having the characteristic of FIG. 5 due to the abnormal voltage rise of the second power supply 2. In the figure, broken lines, solid lines and dotted lines respectively indicate changes in V _B , V _C and V _A , and the fluctuation range is exaggerated for convenience of explanation. Further, V _H having a slight error range with diagonal lines is the cutoff voltage of the high voltage cutoff circuits 12 and 22 built in the power supply.

In the following, along the time t axis, the normal state is from the time point O to the time point x. Second from time x
When the output voltage V _B of the power supply 2 starts to rise, V _C also rises accordingly, and only the second power supply 2 bears the load, and the first
The power supply 1 is in an unloaded state. However, when V _B reaches the cutoff voltage V _H at the time point y, it starts to drop rapidly and drops to 0. V _C also initially drops with this, but when it reaches a normal value at time point z, the first power supply 1
Only bears the load and continues to be normal.

As described above, by using the OR circuit of the high reverse breakdown voltage small reverse current diode such as the PN junction silicon diode, the mutual interference between the two power supplies can be almost completely prevented.

However, as shown in FIG. 5, this type of diode has a large forward voltage drop (rising voltage) of 0.7 to 0.8 V according to the physical law, and therefore power loss in the diode becomes a problem. For example, the loss when a load current of 5 A flows is 5 A × (0.7 to 0.8) V =
It becomes (3.5 to 4) watts (hereinafter referred to as W), which is a very low power efficiency of about 15% of the load power consumption 5A × 5V = 25W.

To solve this problem, it is known that a diode having a forward voltage drop (rising voltage) as small as possible may be used. A typical example of the low forward voltage drop diode is a Schottky barrier silicon diode, which is easily available. Here, this is tentatively referred to as a first type diode. Furthermore, although currently in the prototype stage,
There is a material whose starting voltage is extremely low, which is mainly composed of GaAs, which will be put on the market soon. Here, this is tentatively called a second type diode.

Now, the case where the diodes D1 and D2 are low forward voltage drop diodes will be described. Figure 7
Is a rectification characteristic diagram of a low forward voltage drop diode,
The broken line shows the characteristics of the first type diode, and the solid line shows the characteristics of the second type diode. In this figure as well, similar to FIG. 5, different scales are used in the forward and reverse directions, and both scales are used for convenience of description.

As shown, the forward voltage drop is as low as 0.4 to 0.5 V for the first type diode and 0.2 to 0.3 V for the second type diode. Therefore,
The power loss in the diode when a load current of 5 A flows is 5 A × (0.4 to 0.5) V = (2 to 2 in the case of the first class.
2.5) W, 5A x (0.2 to 0.3) V for the second class
= As small as (1-1.5) W, and power consumption of the load is 5A x 5
With respect to V = 25 W, the power efficiency can be dramatically increased to about 10% for the first type and about 5% for the second type.

[0019]

However, as shown in FIG. 7, this type of diode has a bad reverse characteristic in accordance with the physical law. For example, the reverse withstand voltage of the first type diode is about 40 V and the reverse current is reversed. Is as large as several hundred μA. Further, in the second type diode, the reverse withstand voltage is about 20 V at most, and the reverse current of several hundred mA flows. Therefore, although power efficiency is improved, mutual interference between the two power sources is reignited as an important issue.

For example, when the second power supply 2 fails and the output voltage V _B rises significantly, the following result is obtained. FIG. 8 shows the case of the diode OR circuit having the characteristics shown in FIG.
5 shows a time t vs. voltage V change characteristic at each point of the circuit of FIG. 4 due to an abnormal voltage rise of the second power supply 2. V _B , V _C , V _A , V _H
The same applies to the description of FIG.

Explaining along the time t axis below, the time point O
From time to m is the normal state. That is, the polarity of V _A with respect to V _C is positive. When the output voltage V _B of the second power supply 2 starts to rise from the time point m, V _C also rises accordingly, and the polarity of V _A with respect to V _C turns negative.

Now, let the reverse resistance of the diode D1 be R _R ,
The pseudo load resistance built in the first power supply 1 is R _D. As described above, in the case of the high reverse breakdown voltage small reverse current diode, that is, in the case of R _R >> R _D , the mutual interference action was not a problem at all. However, in the case of bad diode with reverse characteristics, i.e. R _R is R _D comparable, if to a slightly larger value, since already the output voltage is a first power supply 1 is applied to the R _D, According to the superposition principle, even a slight increase in V _C invites an increase in V _A and reaches V _H at time n. Therefore, there is a high probability that the high voltage cutoff circuit 12 of the first power supply 1 also malfunctions shortly before and after the operation of the high voltage cutoff circuit 22 of the second power supply 2, and when it malfunctions, V _B , V _C , V after time n. _{All of A} fall rapidly to 0.

The case where the output voltage V _B of the second power source 2 abnormally rises has been described above. However, even when the output voltage V _A of the first power source 1 abnormally drops, the polarity of V _A with respect to V _C Turns negative, and a problem similar to the above occurs relatively. In this case, the high voltage cutoff circuit does not operate, but R
_{Since R} is small, V _C also drops abnormally.

Therefore, the object of the present invention is to solve the above-mentioned drawbacks of the prior art, to improve the power efficiency by using a low forward voltage drop diode, and even when the reverse characteristic is bad, the dual power supply is used. The point is to provide a highly reliable parallel operation power supply circuit that prevents mutual interference between them.

[0025]

FIG. 1 is a principle diagram showing the basic configuration of the present invention. In the figure, 4 is a polarity detection circuit, 5
Is a high voltage cutoff circuit activation circuit, and 6 is a low voltage alarm circuit drive circuit, which form a first power supply. D is one of the diodes forming the OR circuit. In addition, in the block 7 surrounded by a broken line corresponding to the other half, the second circuit which is the same as the circuit on the side of the first power source and which is symmetrically arranged and connected thereto.
It is assumed that the circuit of the power supply, another diode forming the OR circuit, and the load fed in parallel from the first and second power supplies via the diode OR circuit are included.

As shown in the figure, in a parallel operation power supply circuit for supplying current to a load from two power supplies each having a built-in high-voltage cutoff circuit and a low-voltage alarm circuit via a diode OR circuit. A polarity detection circuit 4 for detecting the relative polarity of the anode to the cathode of the diode forming the diode OR circuit, and the polarity detection circuit 4
Receives an affirmative signal to be sent when it detects a positive polarity, sends an activation signal enabling its operation to the high voltage cutoff circuit built in the power source, and sends it when the polarity detection circuit 4 detects a negative polarity. And a high-voltage cutoff circuit activation circuit 5 that suppresses the operation of a high-voltage cutoff circuit built in the power supply.
A low voltage warning circuit drive circuit 6 for sending a drive signal for driving the low voltage warning circuit built in the power source upon receiving an activation signal sent when the polarity detection circuit detects a negative polarity. Characterize.

[0027]

In FIG. 1 of the principle diagram showing the basic configuration of the present invention, when the polarity is normal, that is, when the polarity of V _A with respect to V _C is positive, a positive signal is sent from the polarity detection circuit 4, which activates the high voltage cutoff circuit. It is added to the digitization circuit 5. Upon receiving an affirmative signal, the high-voltage cutoff circuit activation circuit 5 sends an activation signal to the high-voltage cutoff circuit built in the power supply so that the high-voltage cutoff circuit can operate anytime when the operating condition is reached. To do.

Next, at the time of abnormality, that is, when the polarity of V _A with respect to V _C becomes negative, the polarity detection circuit 4 sends an inhibition signal and an activation signal. Of these, the inhibition signal is applied to the high voltage interruption circuit activation circuit 5. When the high-voltage interruption circuit activation circuit 5 receives the inhibition signal, it does not send the activation signal to the high-voltage interruption circuit, so that the high-voltage interruption circuit cannot operate.

On the other hand, the activation signal is applied to the low voltage alarm circuit drive circuit 6. Upon receiving the activation signal, the low-voltage alarm circuit drive circuit 6 sends the drive signal to the low-voltage alarm circuit built in the power source to drive it.

[0030]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 2 is a circuit diagram showing the first embodiment of the present invention.

The figure shows the first part including the load 3 in FIG.
Only a half of the power source 1 side is shown, 1 is a first power source incorporating a high voltage cutoff circuit 12, D1 is a diode forming a diode OR circuit, and 3 is a load. Although the second power source 2 side half is omitted, it is assumed that the same configuration as in FIG. 2 is applied.

In FIG. 2, block 8 is composed of transistors Q1 and Q2, which are commonly connected to point G as a base, and anodes A and C of D1 are connected to emitters, and resistors R0 to R3. The differential amplifier corresponds to the polarity detection circuit 4 in FIG.

The block 9 includes a Zener diode ZD, a transistor Q3, a light emitting portion PC and a light receiving portion p.
A high voltage breakdown circuit including a photocoupler including c, which corresponds to the high voltage cutoff circuit activation circuit 5 in FIG.

R4 and R5 are resistors for applying a base bias to the transistor Q3, R6 is a breakdown current protection resistor,
R7 is a resistance for reinforcing the pseudo load resistance built in the power supply. First, the normal state, that is, the case where the polarity of V _A with respect to V _C is positive will be described.

In this case, in the differential amplifier 8 corresponding to the polarity detection circuit 4, since it is clear that V _A > V _G > V _C , the transistor Q1 is conducting and the transistor Q2 is non-conducting. Therefore, the current flows through the route 1 of A → Q1 → R1 → E, but the current does not flow through the route 2 of C → Q2 → R2 → R3 → E. Therefore, the voltage at the point J sandwiched between R2 and R3. V _{J is} also the pace bias V _K of the transistor Q3.
In both cases, V _J ≈V _K ≈E = 0 (E is assumed to be grounded).

This low (0) level of V _K corresponds to the positive signal in FIG. In the high voltage breakdown circuit 9 corresponding to the high voltage cutoff circuit activation circuit 5, the breakdown voltage of the Zener diode ZD is slightly lower than the cutoff voltage V _{H of} the high voltage cutoff circuit 12 built in the first power supply 1. Value V
Set to _Z. Then, in this case, transistor Q3
Since the base bias of is at the low (0) level, Q3 is in a non-conducting state. Therefore, if the output voltage V _A of the first power supply rises to reach V _Z , the Zener diode ZD breaks down and the photo coupler of A breakdown current flows through the light emitting portion PC and emits light.

The light emission of the PC corresponds to the activation signal in FIG. That is, the photodiode of the light receiving portion pc is turned on, and the high voltage cutoff circuit 12 is activated, that is, activated whenever the operating condition is reached. Therefore, when V _A further rises and reaches V _H , the high voltage cutoff circuit 12 operates immediately to prevent the abnormal voltage rise to the load 3.

Next, a case where an abnormality occurs, that is, a case where the polarity of V _A with respect to V _C becomes negative will be described. In this case, it is clear that V _A <V _G <V _C , so Q2
Becomes conductive and Q1 becomes non-conductive. Therefore, the above route 1
Current is cut off and the current flows through the path 2, so V _J ≈V _C R3 ÷ (R2 + R3) = plus voltage, V
_{K ≒ V J R5 ÷ (R4} + R5) = a positive voltage = high (1) level.

The high (1) level of V _K corresponds to the inhibition signal in FIG. That is, in this case, since the base bias of Q3 has changed to the high (1) level, Q3
Became conductive, so if V _A rises and reaches V _Z , ZD will break down as before, but unlike the above, most of the breakdown current will flow through Q3 and almost no PC will flow. Not flowing. That is, since the PC does not emit light, the activation signal in FIG. 1 is not generated.

Therefore, since the photodiode of pc does not conduct, the high voltage cutoff circuit 12 is not activated, that is, suppressed, and does not operate even if V _A further rises and reaches V _H. As a result, the mutual interference effect due to the abnormally high voltage between the power supplies described above is prevented.

Next, FIG. 3 is a circuit diagram showing a second embodiment of the present invention. This figure shows only the half on the first power supply 1 side, the same configuration should be applied to the half on the second power supply 2 side, and the block diagrams and parts indicated by the reference numerals in FIG. Is the same.

However, in FIG. 3, reference numeral PC of the light emitting portion and reference numeral pc of the light receiving portion of the photocoupler shown in FIG.
They are PCH and pcH, respectively, and a photocoupler of the light emitting portion PCL / light receiving portion pcL and an abnormal light emitting block 10 composed of the latter photocoupler are newly introduced. Also shown is a low voltage alarm circuit 13 built into the first power supply 1.

The abnormal light emission block 9 corresponds to the low voltage alarm circuit drive circuit 6 in FIG. Well, first
The normal and abnormal operations regarding activation of the high-voltage cutoff circuit 12 built in the power supply 1 are exactly the same as those described above with reference to FIG.

Also in the second embodiment, in the normal state, that is, in the case of V _A > V _G > V _C , no current flows through the above-mentioned path 2 passing through the transistor Q2, but in the abnormal state, that is, When V _A <V _G <V _C , current flows only in the path 2. Therefore, a current flows through the light emitting portion PCL of the photocoupler to emit light.

The light emission of this PCL corresponds to the activation signal in FIG. That is, the photodiode of the light receiving unit pcL is turned on, and the low voltage alarm circuit built in the first power supply 1 is immediately driven to issue an alarm or the alarm is transmitted to the maintenance room or the like.

As described above, abnormal power supply includes abnormal voltage rise and abnormal voltage drop, and the abnormal voltage rise can be dealt with by utilizing the high voltage cutoff circuit. According to the second embodiment, an abnormal voltage drop can be detected, and unlike an abnormal voltage rise, there is no risk of burning or destruction of parts, so it is best to simply issue an alarm and take immediate action by a maintenance person. Be done.

In the embodiment, the parallel operation of two power supplies has been described, but it is possible to extend the parallel operation of three or more power supplies.

[0048]

As described above, according to the present invention, since a low forward voltage drop diode can be used as the diode forming the diode OR circuit, a parallel operation power supply circuit with high power efficiency can be realized.

Moreover, with respect to the bad reverse characteristic of the low forward voltage drop diode according to the physical law, the relative polarity of the anode point to the cathode point of the diode is constantly monitored, and at the time of abnormality, that is, when the negative polarity is detected, It is possible to provide a highly reliable parallel-operation power supply circuit by suppressing the operation of the high-voltage cutoff circuit, driving the low-voltage alarm circuit, prompting immediate action, and preventing mutual interference between the two power supplies.

[Brief description of drawings]

FIG. 1 is a principle diagram showing a basic configuration of the present invention.

FIG. 2 is a circuit diagram showing a first embodiment of the present invention.

FIG. 3 is a circuit diagram showing a second embodiment of the present invention.

FIG. 4 is a configuration diagram of a conventional technique.

FIG. 5 is a rectification characteristic diagram of a high reverse breakdown voltage small reverse current diode.

6 is a voltage fluctuation diagram in the case of a diode having the characteristic of FIG.

FIG. 7 is a rectification characteristic diagram of a low forward voltage drop diode.

8 is a voltage fluctuation diagram in the case of a diode having the characteristic of FIG. 7.

[Explanation of symbols]

 4 Polarity detection circuit 5 High voltage interruption circuit activation circuit 6 Low voltage alarm circuit drive circuit

Claims (2)

[Claims] 1. A parallel operation power supply circuit for supplying a current to a load through two diode OR circuits from two power supplies each having a high voltage cutoff circuit and a low voltage alarm circuit built-in, and a diode forming the diode OR circuit. A polarity detection circuit (4) for detecting the relative polarity of the anode with respect to the cathode, and a high voltage cutoff circuit built in the power supply upon receiving an affirmative signal sent when the polarity detection circuit (4) detects a positive polarity. Sending an activation signal that enables that operation,
A high voltage cutoff circuit activation circuit (5) for suppressing the operation of a high voltage cutoff circuit built in the power supply in response to a suppression signal sent when the polarity detection circuit (4) detects a negative polarity. A parallel operation power supply circuit characterized by being performed. 2. A low-voltage alarm circuit which receives an activation signal sent when the polarity detection circuit (4) detects a negative polarity and sends a drive signal for driving it to a low-voltage alarm circuit built in the power supply. A parallel operation power supply circuit according to claim 1, characterized in that it comprises a drive circuit (6).