JP3077172B2 - Switching power supply - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a switching power supply device capable of operating slave power supplies in parallel based on a reference voltage of a master power supply.

[Prior Art] Generally, in this type of power supply device, as shown in FIG. 4, a DC input voltage Vi is applied to a primary winding of a transformer 1 that insulates a primary side and a secondary side, and the primary winding has Switching element 2
Are connected in series to form an inverter. Then, by chopping the input voltage Vi and applying it to the primary winding of the transformer 1, the voltage induced in the secondary winding of the transformer 1 is rectified and smoothed by the rectifying and smoothing circuit 3, and a constant DC output is applied to the load 4. Supply voltage Vo. The power supply apparatus includes a feedback circuit for controlling the switching element 2 based on the output voltage Vo, the dividing the detected voltage by the feedback circuit to the DC output voltage Vo with the resistors R ₁ and R ₂ The detection voltage is supplied to a non-inverting input terminal of the operational amplifier 5, and the detected voltage is compared with a reference voltage supplied to an inverting input terminal. A comparison signal output from the operational amplifier 5 is input to a control IC 6, and the control IC 6 Is converted into a pulse having a conduction width corresponding to the comparison signal, and the switching element 2 is turned on and off by this pulse, so that the output voltage Vo based on the reference voltage is stably obtained. The power supply device includes a control power supply 7 for inputting, for example, a DC input voltage Vi.
(For example, +15 V) is supplied as the power supply of the control IC 6. The output of the control power supply 7 is supplied to a reference voltage generation circuit 8, and the reference voltage generation circuit 8 outputs a reference voltage V _{REF of,} for example, + 5V. The power supply device includes a master / slave circuit 9 for operating a plurality of power supplies in parallel. The reference voltage V _REF output from the reference voltage generator 8 is supplied via an input priority circuit 10. applying a slave terminal 11, and a master terminal 13 to the reference voltage V _REF is supplied via the output priority circuit 12, the input priority circuit 10 is the reference voltage V _REF is the non-inverting input terminal of the operational amplifier 14 to be This operational amplifier 14
The slave terminal of the output terminal via the resistor R ₃ for current limitation
Is connected to 11, an inverting input terminal of the operational amplifier 14 is connected to a connection point between the resistor R ₃ and the slave terminal 11. Further, the output priority circuit 12 is the reference voltage V _REF is applied to the non-inverting input terminal of the operational amplifier 15, the output terminal is connected to the master terminal 13 through a resistor R _4, the inverting input terminal of the operational amplifier 15 a resistor It is connected to a connection point between R ₄ and the master terminal 13.
The reference voltage V _REF supplied to the slave terminal 11 is supplied to the inverting input terminal of the operational amplifier 5 of the feedback circuit by being _divided by the resistors R ₅ and R ₆ . . The resistor R ₃ is set to a resistance R ₄ is greater than the resistance value.

To operate a plurality of power supplies configured in this way in parallel, one of them is used as a master power supply A and the other power supplies are used as slave power supplies B ₁ , B ₂ , B _3, and as shown in FIG. The master terminal 13 of the power supply A is connected in parallel to the slave terminals 11 of the slave power supplies B ₁ , B ₂ , and B ₃ , whereby, based on the reference voltage V _REF supplied to the master terminal 13 of the master power supply A, All the power supplies A, B ₁ , B ₂ , B ₃ are operated in parallel with the reference voltages balanced. These are the master terminal 13 of the master power supply A and the slave power supply.
When the slave terminals 11 of B ₁ , B ₂ , and B ₃ are connected, the resistance R ₃ of the input priority circuit 10 is set to a sufficiently large resistance value compared to the resistance R ₄ of the output priority circuit 12, so that the master power supply The master terminal 13 to the slave terminal 11 according to the reference voltage _{VREF of} A
A current flows into the master terminal 13 or a current flows from the slave terminal 11 to the master terminal 13 to balance the reference voltage.

On the other hand, when the slave terminal 11 is open, the reference voltage V _REF output from the input priority circuit 10 is supplied to the inverting input terminal of the operational amplifier 5 of the feedback circuit.

[Problems to be Solved by the Invention] In the above-described conventional technique, when some abnormality occurs in the master power supply A and the reference voltage V _REF output from the reference voltage generation circuit 8 decreases, the slave power supplies B ₁ and B ₂ , current is drawn from the slave terminal 11 of the B ₃ to the master terminal 13 side of the master power supply a, Therefore abnormality of the master power supply a is Oyobi the slave power supply _{B 1, B 2, B 3} , the slave power supply B _1, B ₂ , the slave supply B ₁ not only the master power supply a also drops the reference voltage V _REF of B _3, B _2, B ₃ also has a problem that falls into the abnormal state.

In response to such a problem, for example, Japanese Patent Application Laid-Open No. 1-129718 discloses that when a comparator provided in a slave regulator detects an inappropriate control signal of the main regulator due to a failure of the main regulator, the comparator and the switch are switched. There is disclosed a stabilized DC power supply that supplies an output from a sense amplifier connected via a current regulator as a current mode control signal and controls each slave regulator.

However, in the configuration disclosed in Japanese Patent Application Laid-Open No. 1-129718, the failure of the main regulator is individually detected by another slave regulator, and when the main regulator actually fails, the slave regulator is provided. Each slave regulator uses its own sense amplifier to perform its own control.In this case, if any abnormality occurs in the main regulator, there is concern that parallel operation cannot be continued between the remaining slave regulators. Occurs.

The present invention has been made to solve the above problems, and has an object to provide a switching power supply device that can continue parallel operation of slave power supplies without affecting the slave power supply side even when some abnormality occurs in the master power supply. Aim.

Means for Solving the Problems The present invention provides a switching element having a slave terminal to which a reference voltage is supplied via an input priority circuit, and a master terminal to which a reference voltage is supplied via an output priority circuit. A plurality of power supplies for supplying a reference voltage supplied to the slave terminal for comparison with a detection voltage in a feedback circuit for controlling the power supply, one of which is a master power supply, the other is a slave power supply, and the master is a power supply. In a switching power supply device in which a master terminal of a power supply is connected to a slave terminal of the slave power supply and the slave power supplies are operated in parallel based on a reference voltage of the master power supply, the switching operation is performed in an abnormal operation state of the power supply and the master terminal output A switch means for shutting off is connected to the output side of the output priority circuit, and when an abnormality occurs in the master power supply, The slave terminals connected to each other are configured to balance reference voltages between the slave power supplies.

[Operation] According to the above configuration, when the master power supply becomes abnormal, the switch means is turned off to disconnect the master terminal of the master power supply, and the slave power supplies are connected in parallel by balancing the reference voltage by the mutually connected slave terminals. Be driven. This allows the slave power supply to continue supplying a stable output voltage to the load while continuing the parallel operation between the slave power supplies without being affected by the abnormality of the master power supply.

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. 4 and 5 are denoted by the same reference numerals, and detailed description thereof will be omitted.

FIG. 1 shows a first embodiment of the present invention, in which a DC input voltage Vi
Is applied to the primary winding of the transformer 1, and the switching element 2
The voltage induced in the secondary winding by the on / off operation is rectified and smoothed by the rectifying and smoothing circuit 3 and supplied to the load 4, and the operational amplifier 5 detects the reference voltage V _REF supplied to the slave terminal 11. The comparison with the voltage and the control IC 6 controls the switching element 2 to turn on and off based on the compared signal are the same as in FIG.

In the master / slave circuit 9, the slave terminal 11
Input priority circuit 10 side is constituted by FIG. 4 similarly to operational amplifier 14 and resistors R _3, even if the output priority circuit 12 of the master terminal 13 side from FIG. 4 similarly to operational amplifier 15 and resistors R ₄ It is configured. However, differs from the Fig. 4 in that the inserted and connected FET16 switch means serving MOS type between the resistor R ₄ and the master terminal 13. That is, in the FIG. 1, as well as connecting the source of the FET16 to a connection point between the resistor R ₄ and the inverting input terminal of the operational amplifier 15, and connects the drain and the master terminal 13. Further, an internal voltage + V, for example, an output voltage of the control power supply 7, which is divided by a resistor R ₇ and a resistor R ₈ , is applied to the gate of the FET 16. Then, similarly to FIG. 5, the master terminal 13 of the master power supply and the slave terminals of the slave power supplies B ₁ , B ₂ , B ₃
11 and connected.

Next, the operation of the above configuration will be described. During a normal operation, the internal voltage + V is divided by the resistors R ₇ and R ₈ and F
The FET 16 is supplied as a gate bias voltage of the ET 16, and the FET 16 is turned on by the gate bias voltage, so that current can flow in both directions between the source and the drain.
Then, in a state where the reference voltages are balanced based on the base voltage V _REF of the master power supply A, the parallel operation of the slave power supplies B ₁ , B ₂ , and B ₃ can be performed as in FIG.

On the other hand, if any abnormality occurs in the master power supply A,
The internal voltage + V decreases, the gate bias voltage decreases, and FE
T16 is turned OFF, the master terminal 13 of the master power supply A is disconnected from the slave terminal 11 of the slave power source _{B 1, B 2, B 3} ,
As a result, the slave power supplies B ₁ , B ₂ , and B ₃ are operated in parallel by balancing the reference voltages by the mutually connected slave terminals 11.

As described above, in the above-described embodiment, when an abnormality occurs in the master power supply A, the FET 16 is turned off to shut off the master terminal 13, so that any abnormality occurs in the master power supply A and the reference voltage V _{Even if REF} decreases, there is no fear of affecting the slave power supplies B ₁ , B ₂ , B ₃ . When the master power supply A becomes abnormal, the slave power supply
The slave terminals 11 connected to B ₁ , B ₂ , and B ₃ enable the parallel operation to be continued in a balanced state of the reference voltage V _REF of each slave terminal 11.

FIG. 2 shows a second embodiment of the present invention. The same parts as those in the first embodiment are denoted by the same reference numerals and the description of the same parts is omitted. sources with is connected to the resistor R ₄ connected to the output terminal of the operational amplifier 15, the drain is connected to the connection point between the inverting input terminal of the master terminal 13 and the operational amplifier 15. When an abnormality occurs in the master power supply A, the output of the master terminal 13 is shut off by turning off the FET 16 as in the first embodiment, and the slave power supplies B ₁ , B ₂ , B ₃
, And the slave power supplies B ₁ , B ₂ , and B ₃ operate in parallel while balancing the reference voltages among the slave power supplies B ₁ , B ₂ , and B ₃ . In this case, the current from the slave terminal 11 flows from the master terminal 13 to the inverting input terminal of the operational amplifier 15.
There is no fear of affecting B ₁ , B ₂ and B ₃ .

FIG. 3 shows a third embodiment of the present invention, in which the same parts as those in the first embodiment are denoted by the same reference numerals and the description of the same parts is omitted. In this example, a relay 17 is used instead of the FET 16. is obtained by construction, the relay contacts 17A are inserted and connected between the resistor R ₄ and the master terminal 13, the resistor R _7, R ₈
And an exciting coil 17B is connected in series. Then, in the master power supply A normal operation the exciting current by the internal voltage + V is closed relay contact 17A is to flow to the exciting coil 17B, the master terminal 13 based on forward voltage V _REF via the operational amplifier 15 and resistors R ₄ Side to perform normal parallel operation. On the other hand, if any abnormality occurs in the master power supply A, the internal voltage + V decreases, the current flowing in the exciting coil 17B decreases, and the relay contact 17A is opened, whereby the master power supply A becomes the slave power supplies B ₁ , B ₂ , B ₃ and separated
A slave power supply is provided by the mutually connected slave terminals 11.
Parallel operation is continued while balancing the reference voltages among B ₁ , B ₂ , and B ₃ .

Note that the present invention is not limited to the above embodiments, and various modifications can be made within the scope of the present invention. For example, the switching power supply is not limited to the forward type and can be applied to various types such as a flyback type, and a transistor can be used as a switching element of the inverter. Further, the switch means of the master / slave circuit is not limited to the FET and the relay, and another switch element having a characteristic that current flows in both directions at the time of the ON operation may be used. The internal voltage for controlling the ON / OFF operation of the switch means detects various abnormal conditions inside the power supply and provides an appropriate voltage which causes a voltage drop, so that the switch means can be used even when abnormal heating occurs, for example. It can be turned off to shut off the master terminal output.

[Effect of the Invention] The present invention has a slave terminal to which a reference voltage is supplied via an input priority circuit, and a master terminal to which a reference voltage is supplied via an output priority circuit, and controls a switching element. A plurality of power supplies that supply a reference voltage supplied to the slave terminal for comparison with the detection voltage in the above, one of which is a master power supply, the other is a slave power supply, and the master terminal of the master power supply is In a switching power supply device connected to a slave terminal of the slave power supply and operating the slave power supply in parallel based on a reference voltage of the master power supply, switch means for turning off the power supply in an abnormal operation state of the power supply and cutting off the output of the master terminal. Are connected to the output side of the output priority circuit, and when an abnormality occurs in the master power supply, they are connected to each other. Wherein the slave terminals are configured to balance reference voltages between the slave power supplies,
Even if any abnormality occurs in the master power supply, it is possible to provide a switching power supply that can continue the parallel operation of the slave power supplies without affecting the slave power supply.

[Brief description of the drawings]

FIG. 1 is a circuit diagram of a master-slave circuit showing a first embodiment of the present invention, FIG. 2 is a circuit diagram of a master-slave circuit showing a second embodiment of the present invention, and FIG. FIG. 4 is a circuit configuration diagram of a switching power supply showing a conventional example, and FIG. 5 is a general schematic description showing a connection state between a master power supply and a slave power supply. FIG. 5 Operational amplifier (feedback circuit) 8 Reference voltage generation circuit 10 Input priority circuit 11 Slave terminal 12 Output priority circuit 13 Master terminal 16 FET (switch means) 17 Relay (switch means) A ...... master power supply _{B 1, B 2, B 3} ...... slave supply

Claims (1)

(57) [Claims] 1. A detection circuit in a feedback circuit having a slave terminal to which a reference voltage is supplied via an input priority circuit and a master terminal to which a reference voltage is supplied via an output priority circuit, and controlling a switching element. A plurality of power supplies for supplying a reference voltage supplied to the slave terminal are provided for comparison with one another, one of which is a master power supply, the other is a slave power supply, and the master terminal of the master power supply is the slave power supply. A switching terminal connected to a slave terminal of the switching power supply and operating the slave power supply in parallel based on a reference voltage of the master power supply. Connected to the output side of the priority circuit, and when an error occurs in the master power supply, Switching power supply device being characterized in that configured to balance the reference voltage in the slave power supply to each other by pins.