JPH0126263B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a power supply device that synchronizes a plurality of switching regulators installed together to individually drive a plurality of loads.

BACKGROUND ART Generally, batteries are used as drive power sources in various portable or vehicle-mounted electronic devices such as video tape recorders (VTRs) and video cameras.
In this type of power supply, the terminal voltage may fluctuate greatly due to sudden changes in the load caused by switching between various operating modes in the drive equipment, etc., and it is necessary to suppress such fluctuations to stabilize the operation of electronic equipment. In order to achieve this goal, a stabilized power supply device is used.

A switching regulator is used in such a power supply device, but a plurality of switching regulators may be used in parallel in order to obtain an output voltage corresponding to a large number of loads.

FIG. 1 shows a conventional separately excited switching regulator used in such a power supply device.
In this switching regulator, input terminal 2
The ripple component of the DC input V _i supplied between A and 2B is removed by the ripple absorbing capacitor 4 installed between the input terminals 2A and 2B, and it is converted to AC by the switching transistor 6, and then connected to the diode. 8. After being converted into direct current again by a direct current regeneration circuit 14 comprising a chiyoke coil 10 and a capacitor 12, a stabilized direct current output V ₀ is taken out from output terminals 16A and 16B.

There is a DC output V _p between the output terminals 16A and 16B.
Resistors 18 and 20 for dividing and extracting the voltage of
are connected in series, and the divided voltage generated at the connection point of these resistors 18 and 20 is compared with a reference voltage provided by a reference power supply 24 by an error amplifier 22, and the error thereof is detected. This error output is applied to the non-inverting input terminal of the comparator 26, and the triangular wave output shown in FIG. 2A from the reference waveform generating circuit 28 is applied to the inverting input terminal. In FIG. 2A, V _e is the error output generated by error amplifier 22. In FIG. That is, both such inputs are connected to comparator 2.
6, the comparator 26 performs a pulse width modulation operation, producing the pulse shown in FIG. 2B, the pulse width of which is controlled by the error output.
This pulse serves as a control input to the transistor 30, and in response to this switching operation, a pulsed drive current flows through the switching transistor 6 via the resistor 32 and the transistor 30, and the switching transistor 6 performs a switching operation. Note that the resistor 34 is a bias resistor for the switching transistor 6.

By the way, when a power supply device is configured by installing multiple sets of such switching regulators, each switching regulator requires an individual reference waveform generation circuit, which increases the complexity of the configuration. If the oscillation frequencies of the respective reference waveform generation circuits do not match, extremely inconvenient beat disturbances may occur. In particular, the generation of such beats causes noise in the oscillation and signal processing in the internal circuits of VTRs, video cameras, etc., causing malfunctions, so prevention is required.

A similar problem also occurs when a plurality of self-excited switching regulators each having an oscillation control section are installed.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a power supply device that unifies the reference waveform generation circuit for a plurality of switching regulators installed in parallel, and also achieves synchronization of the switching operations of each switching regulator. do.

That is, the power supply device of the present invention includes a first transistor (transistor 84) that generates a current according to a voltage difference between an output detection voltage applied to the base and a reference voltage applied to the emitter; A second transistor (transistor 74) is supplied to control the switching operation, and a third transistor performs the switching operation together with the second transistor and converts the DC input into pulses intermittently.
transistor (switching transistor 5
6) A plurality of switching regulators are installed, and one of the switching regulators (switching regulator 41) is connected to the base and collector of the third transistor and the second transistor. A reference waveform generation circuit that forms a closed loop with the base and collector of the switching regulator through a capacitor to form an oscillation circuit, and generates a reference waveform output synchronized with the pulses obtained by the switching regulator. is installed, and the reference waveform output obtained from this reference waveform generation circuit is sent to another switching regulator (switching regulator 4).
2...4N) to the base of the second transistor.

Furthermore, in the power supply device of the present invention, the reference waveform generation circuit may include an integrating circuit that integrates the pulses to generate the reference waveform output.

Embodiments of the present invention will be described in detail below with reference to the drawings.

FIG. 3 shows an embodiment of the power supply device of the present invention. This power supply device is equipped with a plurality of switching regulators 41, 42...4N, one of which is a self-excited switching regulator, and the other switching regulator is a self-excited switching regulator. The regulators 42...4N are composed of separately excited switching regulators.

Each switching regulator 41, 42...4
Common input terminals 52A and 52B are formed at N, and a ripple absorption capacitor 54 is installed. Therefore, the input terminal 52A,
The ripple included in the DC input V _i applied to the capacitor 52B is absorbed by the capacitor 54.

Then, the DC input V _i is converted into a switching pulse by the switching operation of a switching transistor 56 installed as a third transistor, and then added to a DC regeneration circuit 58 where it is converted into DC and applied to each switch. Ngregulator 4
1, 42...4N output terminals 61A, 61B, 6
2A, 62B... 6NA, 6NB stabilized DC outputs V _p1 , V _p2 ... V _po are taken out individually.

Each switching regulator 41, 42...4
The DC regeneration circuit 58 at N is a diode 6
2, a chiyoke coil 64 and a capacitor 66. The chiyoke coil 64 of this embodiment is composed of primary and secondary coils 64P and 64S. The polarities of the primary coil 64P and the secondary coil 64S are such that the generated pulses are opposite to each other, and the switching pulse generated in the secondary coil 64S is returned to the base of the switching transistor 56 via the differential capacitor 68. has been done. That is, the differential pulse synchronized with the switching pulse via capacitor 68 is applied to the base of switching transistor 56 in addition to the control pulse in order to shorten the switching operation time of switching transistor 56.

Further, a bias resistor 70 is connected between the base and emitter of the switching transistor 56, and a bias resistor 70 is connected between the base and the DC regeneration circuit 5.
A transistor 74 as a second transistor is connected to the output side of the switching transistor 8 through a resistor 72, with its collector connected to the base side of the switching transistor 56 and its emitter connected to the DC reproduction output side.

And in the switching regulator 41,
A capacitor 76 and a resistor 7 are connected in series between the base and collector of the transistor 74 and the base and collector of the switching transistor 56.
The switching transistor 56, the transistor 74, and the feedback circuit 80 constitute an oscillation circuit, and a bias is applied to the base of the transistor 74 from the DC input side via a resistor 82. ing. Therefore, a feedback circuit 80 is connected to the base of transistor 74.
Since the signal is positively fed back from the collector of the switching transistor 56 by the switching transistor 56, the switching transistor 56 and the transistor 74 oscillate, and the transistor 74 functions as a pulse width controlled oscillator that causes a drive current to flow through the switching transistor 56. , and also has a function of adding the drive current to the DC reproduction output.

The base of this transistor 74 is connected to the collector of a transistor 84 installed as a first transistor for controlling its operating current, and the emitter of this transistor 84 is connected to a constant voltage diode 86 for setting a reference voltage. It is connected with the anode on the reference potential point side, and
A DC output is provided through a resistor 88. A resistor 9 connected in series between the output terminals 61A and 61B is connected to the base of the transistor 84.
The output detection voltage obtained between the connection point of 0 and 92 and the ground point is applied, and this output detection voltage and the reference voltage set by the voltage regulator diode 86 are compared by the transistor 84. A voltage difference between the output detection voltage and the reference voltage is determined, and a current flows through the transistor 84 according to the voltage difference. Since this current is supplied to the base of transistor 74, the switching operation of transistor 74 is controlled in accordance with the current.

Also, switching regulator 42...4N
is the feedback circuit 80 of the switching regulator 41
This is the configuration excluding the output terminals 62A and 62B.
. . . DC output V _{p2 .} . . V _po having a predetermined voltage value is taken out from 6NA and 6NB.

The switching pulse generated by the switching transistor 56 of the switching regulator 41 is taken out from its collector and applied to the reference waveform generation circuit 94. This reference waveform generation circuit 94 generates a reference waveform voltage such as a triangular wave or a sawtooth wave in response to a switching pulse taken out from the collector side of the switching transistor 56, and the obtained reference waveform voltage is applied to each switching leg. The generator 42...is added to the base of the 4N transistor 74.

In the above configuration, the operation is explained as follows.
The transistor 74 for causing a drive current to flow through the switching transistor 56 oscillates because the switching pulse is positively fed back to its base. In this oscillation operation, transistor 7
The base current of 4 is controlled by transistor 84, and this control is dependent on the DC output. Therefore, the control pulse applied to the base of the switching transistor 56 by the oscillation of the transistor 74 is a pulse width modulation signal corresponding to the fluctuation level of the DC output, and as a result, the switching transistor 56 is in the switching state. do.

Such control operations are performed continuously, and the DC input V _i applied to the input terminals 52A and 52B passes through the switching transistor 56 and is converted into a switching pulse, and then passes through the DC regeneration circuit 58 and becomes the DC output V. _p1 is taken out from the output terminals 61A and 61B. When the DC output fluctuates due to changes in the load, etc., a stabilizing control operation corresponding to the fluctuation is instantaneously performed, and a constant DC output can be continuously supplied to the load.

In such a switching operation, a switching pulse generated at the collector of the switching transistor 56 is applied to the primary coil 64P of the York coil 64, and a switching pulse whose polarity is reversed is generated at the secondary coil 64S. This pulse is differentiated by capacitor 68 and then applied to the base of switching transistor 56. Each edge of this differential pulse corresponds to an edge portion of the switching pulse, and since the directions of increase and decrease in potential level are opposite to each other, the switching transistor 56
It functions to support the ON or OFF operation. As a result, it becomes possible to shorten the switching operation time of the switching transistor 56, and the switching operation time of the switching transistor 56 can be shortened.
The pulses formed through this process have short rise and fall times, that is, they have steep edges. As a result, power loss can be reduced and conversion efficiency can be improved.

Furthermore, the switching pulse generated at the collector of the switching transistor 56 by such a switching operation is transmitted to the reference waveform generating circuit 94.
is applied to obtain a reference waveform voltage such as a triangular wave or a sawtooth wave. This reference waveform voltage is individually applied to the base of each transistor 74 of the separately excited switching regulators 42...4N, and is used as a pulse width control input. Therefore, similar pulse width control is performed by this control input, and in the switching regulators 42...4N, the DC input V _i applied to the input terminals 52A, 52B is controlled by the switching transistor 56. After converting it into a switching pulse and converting it into DC in the DC regeneration circuit 58, a plurality of DC outputs V _p2 . . . V _po can be obtained.

In this way, the switching regulator 42...
4N is provided with a pulse obtained by waveform shaping the switching pulse formed by the switching transistor 56 of the switching regulator 41 as a reference waveform, so that the switching frequency is periodized. Therefore, compared to conventional circuits in which a separate reference waveform generation circuit is installed, there is no beat generation due to frequency deviation.
Beat disorders can be suppressed. Further, there is no need to separately provide a reference waveform generation circuit unlike the conventional circuit, and the configuration can be simplified.

Next, FIG. 4 shows an example of a specific circuit configuration of the power supply device of the present invention, and FIG. 5 shows its operating waveforms. In this embodiment, the reference waveform generation circuit 94 is configured as a reference waveform generation circuit that converts a switching pulse into a desired reference waveform, and is configured as an integrating circuit consisting of a resistor 96 and a capacitor 98, and its integral output is Each switching regulator 42...4N transistor 7 is connected via a capacitor 100.
It is applied to the base of 4. Note that the time constant of the integrating circuit is set to a value that provides good linearity and peak value of the waveform after waveform shaping.

By configuring the reference waveform generation circuit 94 in this manner, the switching pulse shown in FIG. 5A generated at the collector of the switching transistor 56 of the switching regulator 41 is converted into the triangular wave shown in FIG. 5B. be done. This triangular wave is applied to each switching regulator 4 via a capacitor 100.
2...4N is applied to the base of the transistor 74. If the control level formed by the transistor 74 is V _d shown in FIG. 5B, then a control pulse shown in FIG. 5C is formed on the collector side of the transistor 74. Although this control pulse has a phase shift between the switching pulses shown in FIG. 5A, its frequency does not change, so no problems such as beats occur.

By configuring the reference waveform generating circuit 94 as an integrating circuit in this manner, the number of constituent elements is extremely small, and the power supply device can be made smaller by simplifying the structure and reducing the number of elements.

As explained above, according to the present invention, when a plurality of switching regulators are installed together, it is possible to synchronize the switching frequencies of each switching regulator, thereby eliminating beats that adversely affect waveform processing. The generation of the reference waveform output can be suppressed, the generation of the reference waveform output can be simplified, and the power supply device can be downsized.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram showing a conventional switching regulator, FIG. 2 is an explanatory diagram showing operating waveforms of the switching regulator shown in FIG. 1, and FIG. 3 is an implementation of the power supply device of the present invention. Circuit diagram showing an example, 4th
The figure is a circuit diagram showing a specific example of the circuit configuration of the power supply device of the present invention, and FIG. 5 is an explanatory diagram showing operating waveforms of the power supply device shown in FIG. 4. 41, 42...4N...Switching regulator, 56...Switching transistor (third transistor), 58...DC regeneration circuit, 7
4...transistor (second transistor), 8
4...transistor (first transistor), 9
4...Reference waveform generation circuit.

Claims (1)

[Scope of Claims] 1. A first transistor that generates a current according to a voltage difference between an output detection voltage applied to the base and a reference voltage applied to the emitter, and a switching operation in which the current is supplied to the base. second controlled
A plurality of switching regulators are installed, each of which includes a transistor and a third transistor that performs a switching operation together with this second transistor and converts DC input into pulses intermittently. A closed loop is formed in the switching regulator via a capacitor between the base and collector of the third transistor and the base and collector of the second transistor, and the switching regulator A reference waveform generation circuit is installed that generates a reference waveform output synchronized with the pulse obtained in A power supply device characterized by supplying power to the base of. 2. The power supply device according to claim 1, wherein the reference waveform generation circuit uses an integrating circuit that integrates the pulse and generates the reference waveform output.