JP2583479Y2 - DC power supply with multiple DC converters connected in parallel - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a DC power supply in which DC converters such as switching regulators are connected in parallel.

Generally, a separately-excited switching regulator used in a DC power supply of this type includes an error amplifier for comparing an output voltage with a reference voltage, a triangular wave generation circuit,
It includes a comparator that forms a PWM pulse by comparing a triangular wave with an error signal, and a switching element that turns on and off in response to the PWM pulse. Generally, control parts such as an error amplifier, a triangular wave generation circuit, and a comparator are integrated circuits (I
C), wherein the oscillation capacitor and the timing resistor for obtaining the ramp voltage of the triangular wave generating circuit are externally connected. When operating switching regulators in parallel, switching regulator (master)
Attach a timing resistor and a capacitor for oscillation to operate the oscillation circuit and generate a triangular wave. In another switching regulator (slave), the operation of the oscillation circuit is stopped and the oscillation capacitor terminal is connected to the oscillation capacitor on the master side. As a result, the switching regulator on the slave side operates with the triangular wave output on the master side, thereby enabling synchronous operation.

[0003]

However, in this DC power supply, if the capacitor connection terminal on the slave side goes to the ground level for some reason, the terminal of the oscillation capacitor of the master also goes to the ground, and the triangular wave is generated by both the master and the slave. It becomes impossible to obtain. Further, if an abnormality occurs in the triangular wave generation circuit on the master side, a triangular wave cannot be obtained on the slave side. Therefore, power supply becomes impossible due to the failure of one of the master and the slave. This species
Multiple triangular wave generation capacitors to solve the problem
JP-A-56-9819 discloses connecting a resistor between
No. 6,086,045. But the resistance is impedance
Noise adds noise to one of the oscillators
And it is difficult to synchronize this oscillator with another oscillator
Out of synchronization. Also, until I return
The time in is longer.

[0004] Therefore, an object of the present invention is to solve the problem even if one of a plurality of DC converters connected in parallel fails.
An object of the present invention is to provide a DC power supply that can maintain power supply while maintaining synchronization .

[0005]

In order to achieve the above object, the present invention comprises a plurality of DC converters connected in parallel, wherein the DC converters are switching elements for controlling a voltage level. A triangular wave generating circuit, and a control pulse forming circuit that forms a control pulse for turning on and off the switching element based on an output of the triangular wave generating circuit. generating circuit includes a capacitor for obtaining the ramp voltage, respectively, it said balancing capacitor therebetween of the capacitor of the plurality of direct-current converter is of concerning to a DC power supply is connected.

[0006]

In the present invention, the triangular wave generating circuits of the plurality of DC converters each have a capacitor for obtaining a ramp voltage, and a capacitor for balance is provided between these capacitors.
Since the capacitors are connected, the plurality of capacitors are related to each other to form a triangular wave, thereby enabling synchronous operation. Further, abnormality in any of a plurality of triangular wave generating circuit is limited thus mutual interference to the balancing capacitor occurs, the operation of the rest of the triangular wave generating circuit is ensured, abnormality occurs in the plurality of direct-current converter The power supply can be continued by the DC converter that is not used. In addition, balance conditioner
The impedance of the sensor decreases as the frequency increases.
Noise is added to one triangular wave generation circuit,
When the output waveform becomes abnormal, another triangular wave generation circuit
The output waveform also changes at the same time to ensure synchronization
You.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A DC power supply according to an embodiment of the present invention will be described below with reference to FIGS. The DC power supply shown in FIG. 1 is configured by connecting first and second DC converters 1 and 2 in parallel. The first and second DC converters 1 and 2 connected to the common DC power supply 3 and the common load 4 include transistors 5 and 6 as conversion switching elements, transformers 7 and 8, and a rectifier diode 9. , 10, smoothing diodes 11 and 12, smoothing reactors 13 and 14, and smoothing capacitors 15 and 16
, Output voltage detecting resistors 17, 18, 19, 20, reference voltage sources 21, 22, error amplifiers 23, 24, comparators 25, 26 as control pulse forming circuits, and triangular wave generating circuits 27, 28. , Timing resistors 29, 3
0, oscillation capacitors 31 and 32, and a balance capacitor C1.

Since the first and second DC converters 1 and 2 have substantially the same configuration, only the first DC converter 1 will be described in more detail here. The transistor 5 is connected to the DC power supply 3 via the primary winding 7a of the transformer 7. Since the comparator 25 is connected to the base (control terminal) of the transistor 5, the comparator 2
The transistor 5 turns on and off in response to the PWM pulse output from the switch 5. Diodes 9 and 10, reactor 13 and capacitor 1 are connected to secondary winding 7 b of transformer 7.
5 is connected, and the output line 3
3 is connected to the load 4. Voltage detection resistors 17, 18
Is connected between the output line 33 and the ground, and this voltage dividing point is connected to the error amplifier 23. Error amplifier 2
3 sends to the comparator 25 a signal corresponding to the difference between the reference voltage of the reference voltage source 21 and the detection voltage. Comparator 25
Compares the triangular wave voltage obtained from the triangular wave generation circuit 27 with the error signal to form a PWM wave and sends it to the transistor 5.

The triangular wave generating circuit 27 generates a triangular wave with a timing resistor 29 connected between the terminal T1 and the ground and an oscillation capacitor 31 connected between the terminal T2 and the ground. Similarly, in the triangular wave generation circuit 28 of the second DC converter 2, the timing resistor 30 is connected between the terminal T3 and the ground, and the oscillation capacitor 32 is connected between the terminal T4 and the ground. . In order to synchronously generate a triangular wave voltage from the first and second triangular wave generating circuits 27 and 28, capacitors 31 and 3 are used.
2, a balance capacitor C1 is connected between the terminals T2 and T4.

As shown in FIG. 2, the triangular wave generating circuit 27 includes five transistors Q 1, Q 2, Q 3, Q 4, Q 5
, Five resistors R1, R2, R3, R4, R5, two comparators Z1, Z2, two reference voltage sources Vr1,
Vr2 and one flip-flop FF. A timing resistor 29 and an oscillation capacitor 31 are connected to the terminals T1 and T2. When the oscillation capacitor 31 periodically repeats charging and discharging, the voltage VCT between both terminals of the oscillation capacitor 31 changes with a constant gradient, and a triangular wave is obtained. The control circuits of the transistors 5 and 6 of the DC converters 1 and 2 have MB51s sold as control ICs by Mitsubishi Electric Corporation.
995 or MB37 sold by Fujitsu Limited
69A or MB3770 is used.

Since the frequency of the triangular wave obtained from the triangular wave generating circuit 27 is determined by the product of the resistance value Rt of the timing resistor 29 and the capacitance value Ct of the oscillation capacitor 31, the timing resistor connected to the second triangular wave generating circuit 28 is used. 3
0 and the value of the oscillation capacitor 32 are the same Rt, C
Set to t. Thus, the first and second triangular waves W1 and W2 are generated from the first and second triangular wave generating circuits 27 and 28 at the same frequency as shown in FIG. By the way, when the first and second triangular wave generation circuits 27 and 28 start operating, the phases of the first and second triangular waves W1 and W2 do not always match. However, since the balance capacitor C1 is connected between the two oscillation capacitors 31 and 32, a synchronizing action occurs and W1 and W2 match. That is, at a certain time t, the first triangular wave W1
Is higher than the voltage of the second triangular wave W2,
A part of the charging current of the first oscillation capacitor 31 flows into the second oscillation capacitor 32. Accordingly, the second oscillation capacitor 32 is connected to the original charging current supplied based on the second triangular wave generation circuit 28 and the first triangular wave generation circuit 2.
It is charged by the sum of the current flowing from the 7 side. As a result, the voltage of the second oscillation capacitor 32 is corrected to a higher voltage, and the voltage of the first oscillation capacitor 31 is corrected to a lower voltage. .

If the oscillation capacitor 32 of the second DC converter 2 is short-circuited or opened for some reason while the first and second DC converters 1 and 2 are operating in parallel, the second triangular wave No triangular wave is generated from the generating circuit 28, and the second DC converter 2 is substantially stopped. However, the first DC converter 1 continues to operate. That is, even if the second oscillation capacitor 32 is short-circuited or opened, the first oscillation capacitor 31 is separated from the second oscillation capacitor 32 by the balance capacitor C1. Keeps generating a triangular wave. Therefore, it is possible to prevent the worst case in which the entire power supply stops.

[0013]

[Modifications] The present invention is not limited to the above-described embodiment, and for example, the following modifications are possible. (1) As shown in FIG. 4, a third triangular wave generating circuit 40 is provided, and a timing resistor 41 and an oscillating capacitor 42 are connected to the third triangular wave generating circuit 40. The converters 1 and 2 can be operated in parallel. In this case, the second and third oscillation capacitors 3
A balancing capacitor C2 is added between the two. (2) When three DC converters are operated in parallel, as shown in FIG. 5, the first, second and third oscillation capacitors 31, 32 and 42 are replaced with three balance capacitors C1, C2 and C3. May be combined with each other. (3) When the first, second, and third DC converters are operated in parallel, the second and third oscillation capacitors 32, 4
2 can be connected via first and second balancing capacitors C1 and C2. ( 4 ) The DC converters 1 and 2 are not limited to the type shown in FIG. 1 and may be of another type. For example, a chopper circuit that performs PWM control may be used. Also, PW
A DC converter including an M inverter may be used. ( 5 ) The triangular wave generation circuits 27 and 28 are not limited to the circuit shown in FIG. 2 and can be variously modified. That is, any device may be used as long as a triangular wave is generated by charging and discharging the capacitor.

[Brief description of the drawings]

FIG. 1 is a circuit diagram illustrating a DC power supply device according to an embodiment.

FIG. 2 is a circuit diagram illustrating a triangular wave generation circuit of FIG. 1 in detail.

FIG. 3 is a waveform diagram showing a relationship between two triangular waves in the DC power supply device of FIG.

FIG. 4 is a circuit diagram showing a triangular wave generating portion of a modification.

FIG. 5 is a circuit diagram showing a triangular wave generating portion of another modification.

FIG. 6 is a circuit diagram showing a triangular wave generating portion of still another modification.

[Explanation of symbols]

 1,2 DC converter 31,32 Oscillation capacitor C1 Balancing capacitor

Claims (1)

(57) [Scope of request for utility model registration] A plurality of DC converters connected in parallel, the plurality of DC converters being based on a switching element for controlling a voltage level, a triangular wave generating circuit, and an output of the triangular wave generating circuit. And a control pulse forming circuit that forms a control pulse for turning on and off the switching element.The triangular wave generating circuits of the plurality of DC converters each include a capacitor for obtaining a ramp voltage. DC power supply apparatus characterized by balancing capacitor is connected between each other of the capacitors of said plurality of direct-current converter.