JPH0888971A - Current balance type switching power source - Google Patents

Abstract

PURPOSE: To enable this switching power source to generate an alarm signal immediately even when fault occurs in one unit by possessing an abnormality judger, which compares the unbalance voltage of a current detector with a reference voltage, and generates an abnormality signal in case the absolute value of the unbalance voltage is larger than the absolute voltage of reference voltage, at the latter stage of the current detector. CONSTITUTION: The current on the primary side or the secondary side of a transformer is detected, and the unbalance voltage with the primary current or secondary current of the transformer 31 of other switching power source 14n is detected through a CB terminal 43 with a current detector 35, and it outputs the unbalance voltage. An abnormality judger 10 is provided at the latter stage of a current detector 35, and it compares the unbalance voltage from the current detector 35 with reference voltage, and in case the unbalance voltage is larger than the absolute value of the reference voltage, it generates an abnormality signal. Hereby, even when one unit has gone wrong, it can generate an alarm signal immediately.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a current balance type switching power supply for supplying a stabilized voltage to a load by connecting a plurality of switching power supplies in parallel, and more particularly to detecting abnormalities of individual power supplies during parallel operation.

[0002]

2. Description of the Related Art Conventionally, a switching power supply has been used as a power supply of several V (volt) required for electronic equipment. For example, a plurality of switching power supplies are connected in parallel to a large electronic device such as an LSI tester or a large computer system to supply necessary power of several KW (kilowatt) or more.

Therefore, switching power supplies for the purpose of parallel operation have been conventionally developed. For example, Japanese Patent Publication No. 6-26473 discloses a "current balance type switching regulator" which is a switching regulator which can equalize the load sharing to extend the life, reduce the fluctuation of the output voltage, and facilitate the adjustment. Has been done.

FIG. 3 is a block diagram of the above patent publication, and FIG.
FIG. 5 shows an explanatory diagram of the current detection unit 35, and FIG. 5 shows a configuration diagram during parallel operation, and a conventional technique of the current balance type switching power supply will be described. As shown in FIGS. 3 and 5, a plurality of switching power supplies 341 to 34n are connected in parallel to supply power to the load. The configuration of the switching power supply 34i includes a voltage setting unit 36 that sets an output voltage and a voltage setting unit 3 for the voltage setting unit 36.
An adder 37 for adding the output voltage of 6 and the unbalanced voltage;
A switching controller 33 that drives the switching element 32 by performing pulse width control with a voltage that is error-corrected between the output voltage of the adder 37 and the feedback voltage of the output voltage of the switching power supply 34i, the switching element 32, and the switching element 32. Transformer 31 that drives the current on the primary side when driven
And the rectifying / smoothing unit 4 connected to the secondary side of the transformer 31.
0 and a current detector 35 that detects the primary side current of the transformer 31 and generates an unbalanced voltage for parallel operation of the plurality of switching power supplies 34i based on the detected value.

As shown in FIG. 4, the current detecting section 35 detects the current on the primary side of the transformer 31 by a current detecting means such as a current transformer CT, and a resistor R1 and a diode d.
1. By a closed loop of the capacitor C1 and the resistor R2, it is taken out as a direct current detection value and charged in the capacitor C1.
The detected value is taken out to the CB (current balance) terminal 43 through the resistor R3. Then, when the balance of the parallel operation of the switching power supply 34i becomes unbalanced, a current flows through the resistor R3 and the unbalanced voltage generated across the resistor R3 is taken out through the differential amplifier. , The addition unit 37 through the limiter circuit 38
Add to

The current detector 35 and the unbalanced voltage will be described in some detail. The maximum rated current of the current balanced switching power supplies 341 to 34n operating in parallel is
In the same or different cases, the current detection unit 35 sets the value of the resistor R1 so that it becomes the same, for example, 1 V when each maximum rated current is supplied. When a plurality of units are operated in parallel, as shown in FIG.
The B terminals 43 are respectively connected. At this time, when the switching power supplies 34i have the same maximum rated current and the same current is supplied to the load 20 by the respective switching power supplies 34i, the detection value applied to the resistor R3 becomes the same, and therefore the resistance R3 passes through the resistor R3. Switching power supply 34i
No current flows between them, the input voltage of the differential amplifier becomes 0, and an unbalanced voltage does not occur.

However, for example, the switching power supply 3
When the current supplied from 41 to the load 20 is larger than that of the other switching power supply 34i, the switching power supply 341
Since the detection value applied to the resistor R3 of the other switching power supply 34i becomes larger than the detection value of the other switching power supply 34i, the current corresponding to the difference is passed through the resistance R3 to the other switching power supply 34i.
i, a negative unbalanced voltage proportional to the unbalanced voltage is generated across the resistor R3 and is input to the differential amplifier. This negative unbalanced voltage is added to the set value of the output voltage by the adder 37 and input to the switching controller 33 to lower the output voltage of the switching power supply 341. on the other hand,
In the other switching power supply 34i, the ON / OFF period of the switching element 32 is controlled so as to increase the output voltage, so that the currents supplied from all the switching power supplies 34i to the load 20 become the same current again, and the overall balance is improved. To be kept.

The integrating circuit 39 and the limiter circuit 38 are necessary for stabilizing the power supply operation. That is, the integrating circuit 39 can stabilize the operation even when the unbalanced component is rapidly changed due to the load change. Further, the limiter circuit 38 is provided in order to limit an extremely large unbalanced amount when the power is turned on, etc., and quickly converge to a normal control state. The limiter circuit 38 may be, for example, a Zener diode connected in series with opposite polarities.

The MA (master) terminal 41 and the SL (slave) terminal 42 are related to voltage setting. If one of the switching power supplies 34i operating in parallel is the master unit (master unit) and the other units are slave units (slave unit),
By connecting the MA terminal 41 of the master unit and the SL terminal 42 of the slave unit, the setting of the voltage setting unit 36 only needs to be performed by the master unit, and the voltage setting unit 36 of all the switching power supplies 34i can be set at the setting voltage of the master unit. To control.

As described above, in the parallel operation of the current balance type switching power supplies, the CB (current balance) terminals 43 of each switching power supply are connected to each other as shown in FIG. The current supplied to the load 20 is distributed in a well-balanced manner by making the ratio of the detected output current in the detection unit 35 to the rated output current value equal.

[0011]

A plurality of switching power supplies are used when current-balanced switching power supplies are operating in parallel, particularly when the outputs of the respective power supplies are directly short-circuited to supply power to a load. Of these, when the power supply of one part fails, particularly when the operation is performed with sufficient power capacity, the failure cannot be detected and the operation is often continued. This is because the normal switching power supply other than the faulty machine can sufficiently supply the load. However, if the operation is continued as it is, a malfunctioning machine starts to ignite, or the output current of another normal switching power supply increases even if it does not ignite, the internal temperature thereof further rises, and the reliability and the life are shortened. This means that the life of the entire device becomes shorter than the life when the load sharing is averaged. Therefore, some kind of abnormality detection is necessary.

[0012]

In order to detect the above-mentioned abnormality, the present invention constantly monitors the current of the current detecting portion, and when an unbalanced voltage occurs and an abnormal state occurs, the ALM signal ( The configuration is such that an abnormality determination unit that outputs an alarm signal) is provided. The ALM signal is provided with an LED or a lamp for each power source, emits a sound, or outputs the signal from an external terminal, but here the ALM signal is generated. The details will be described below.

First, referring again to FIG. 1, the current detector 35 will be examined. In the case of normal operation, the current on the primary side of the transformer 31 is detected by a current detecting means such as a current transformer CT, and is added to the resistor R3 as a DC detection value by the resistor R1, the diode d1 and the capacitor C1. FIG.
Detects the current on the primary side of the transformer 31, but 2
The secondary current may be detected. Furthermore, through resistor R3, C
It is connected to the B terminal 43. The internal voltage viewed from the CB terminal 43 is 1 V when the rated output current (hereinafter referred to as “power supply capacity”) is supplied to the load 20, and 50% of the power supply capacity.
The resistance value of the resistor R1 is set so as to be about 0.5 V when%.

Now, it is assumed that two switching power supplies 141 and 14n of the same standard are operated in parallel and each is operating at 50% of the power supply capacity. And 141
If the output current becomes 0 due to the failure of the machine, especially when the switching element 32 and the rectifying diode d2 are opened, the 14n machine operates with the power supply capacity of 100% and supplies the current to the load. At this time, the unbalanced current flows from the 14n side to the 141 side. Therefore, in the current detector 35 of 141 units,
The unbalanced voltage becomes a positive voltage, and the positive voltage is added to the addition unit 37. Therefore, the 141 machine tries to increase the voltage to increase the power supplied to the load, but the output current remains 0 due to a failure.

On the other hand, in the current detector 35 of the 14n machine, the unbalanced voltage becomes a negative voltage, and the negative voltage is added to the adder 37, so that the output voltage starts to drop. Then, the limiter circuit 38 operates and does not drop below a certain value, and continues to supply power to the load 20 when the output voltage drops slightly. However, if this state continues, the load on the 14n machine becomes heavy, the internal temperature rises, and the service life and reliability of each component deteriorate.

In order to solve this problem, the present invention has a structure in which an abnormality judging section for constantly monitoring the unbalanced voltage due to the unbalanced current is provided in the subsequent stage of the current detecting section. The abnormality detection unit is composed of a voltage comparator, a reference voltage, and if necessary, an integration circuit. Moreover, depending on the design, an amplifier or an attenuator may be required. The voltage comparator is configured to have a positive voltage comparison, a negative voltage comparison, or both comparisons. This is because the unbalanced voltage is positive or negative, and the ALM signal is generated when the absolute value of the unbalanced voltage is larger than the absolute value of the reference voltage. Examples will be described below.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows a block diagram of an embodiment of the present invention. The same parts as those in FIGS. 3 and 4 are designated by the same reference numerals. In principle, the abnormality determination unit 10 is connected to the output terminal of the unbalanced voltage from the current detection unit 35. This is because the determination is made based on the unbalanced voltage, but since the integrating circuit 15 is also required, it may be taken out from the output terminal of the integrating circuit 39 by sharing the existing integrating circuit. Then, when an abnormal unbalanced voltage occurs, an ALM signal is generated.

The generated ALM signal may be output as it is through the ALM terminal 11, an LED or a lamp may be turned on for each power source, or an ALM sound may be emitted. In the case of system equipment in which the operator is stationed, the operator's console will also be displayed so that the operator can immediately replace or repair the equipment.

2 (A), 2 (B) and 2 (C) are block diagrams showing an embodiment of the abnormality determining section 10. 13a is a positive voltage comparator, 13b is a negative voltage comparator, 12
a and 12b are positive and negative reference power supplies. Reference numeral 15 is an integrating circuit, that is, a low-pass filter, and the existing integrating circuit 39 can be used depending on the situation. 16 is an OR circuit. As mentioned above, although an amplifier and an attenuator may be required depending on the design, they are omitted.

In FIG. 2A, when the unbalanced voltage of the current detector 35 is a positive voltage, that is, the output current of the power supply is abnormally reduced, current is drawn from another device, and the unbalanced voltage becomes a positive voltage. It is the voltage comparator 13a of the abnormality detection unit 10 in the state in which the positive voltage is added to the addition unit 37 by the addition. The ALM signal is generated when the unbalanced voltage is higher than the reference voltage E1. The reference voltage E1 is a positive voltage, and its value is preferably a little larger than the upper limit value of the normal operation range. This value may be variable from the outside by using a variable resistor or the like. Reference numeral 15 is an integrating circuit having a large time constant τ, and an existing integrating circuit 39 can be used for this. This is because if the unbalanced voltage is an instantaneous voltage, there is a high possibility of normal operation, and it is necessary to remove this.

In FIG. 2B, when the unbalanced voltage is a negative voltage, the output current of that voltage abnormally rises, and a negative voltage is applied to the adder 37 to reduce the output current. It is the voltage comparator 13b of the unit 10. Reference voltage E
Reference numeral 2 is a negative voltage, and a value thereof which is generally a little lower than the lower limit value of the normal operation range, that is, a value whose absolute value is a little larger is suitable. This value may also be variable from the outside by using a variable resistor or the like.

Each power source is provided with the voltage comparator 13a shown in FIG. 2A and the voltage comparator 13b shown in FIG.
The abnormal state may be displayed by lighting a red lamp when 3a generates a signal and a yellow lamp when the voltage comparator 13b generates a signal, but as shown in FIG. If there is any abnormality, the ALM is passed through the OR circuit 16.
A signal may be sent to the terminal 11.

Up to now, the current detection of the current detection section 35 has been described by the detection of the primary side current of the transformer 31.
The current is not limited to the secondary current, and the secondary current may be detected. Further, even if only this ALM signal is not sent as a special abnormal signal, when there is another ALM signal, the OR circuit may take the logical sum and share it for display.

[0024]

As described in detail above, when a plurality of current-balanced switching power supplies are operated in parallel, conventionally, even if there is a failure in one power supply, if there is a margin in the overall power supply capacity, it remains as is. Although it was operating, the present invention immediately generates an ALM signal even when there is a failure in one unit, so subsequent actions such as replacement can be taken immediately, safety and reliability are improved, and its effect is great. is there.

[Brief description of drawings]

FIG. 1 is a configuration diagram of an embodiment of the present invention.

FIG. 2 is a configuration diagram of an embodiment of an abnormality determination unit 10 of the present invention.

FIG. 3 is a block diagram described in Japanese Patent Publication No. 6-26473 of the prior art.

FIG. 4 is an explanatory diagram of a current detection unit in FIG.

FIG. 5 is a configuration diagram of current-balanced switching power supply parallel operation of a conventional technique.

[Explanation of symbols]

 10 Abnormality judgment part 11 ALM (alarm) terminal 12a, 12b Reference power supply 13a, 13b Voltage comparator 141-14n Current balance type switching power supply 15a, 15b Integration circuit (low-pass filter) 16 OR circuit 20 Load 30 AC power supply 31 Transformer 32 Switching element 33 Switching control unit 341-34n Current balance type switching power supply 35 Current detection unit 36 Voltage setting unit 37 Adder unit 38 Limiter circuit 39 Integration circuit 40 Rectification / smoothing unit 41 MA (master) terminal 42 SL (slave) terminal 43 CB (current balance) terminal

Claims (2)

[Claims] 1. A switching controller (33) for controlling a switching element (32) connected to a primary side of a transformer (31) in accordance with a secondary side voltage of the transformer (31).
And an unbalanced voltage between the primary side current or the secondary side current of the transformer of another switching power source is detected via the CB terminal (43) by detecting the primary side or secondary side current of the transformer (31). A current detection unit (35) for detecting and outputting, a voltage setting unit (36) for setting an output voltage, an output voltage from the voltage setting unit (36), and an unbalanced voltage from the current detection unit (35). And the switching control unit (3
In the current balance type switching power supply which is composed of an adding section (37) for outputting to 3) and operates by connecting all the CB terminals in parallel operation, the current detecting section (35) is followed by the current detecting section. Division (3
It is characterized by further comprising an abnormality judging section (10) for comparing the unbalanced voltage of 5) with a reference voltage and generating an abnormal signal when the absolute value of the unbalanced voltage is larger than the absolute value of the reference voltage. Current balance type switching power supply. 2. The abnormality judging section (10) comprises a pair of voltage comparators (13a, 13b) and a reference power source (1) for positive and negative voltages.
2a, 12b) and a current balance type switching power supply according to claim 1.