JPS58130772A - Constant-voltage power source - Google Patents

Abstract

PURPOSE:To stabilize the output DC voltage to the wire input/output variation by constructing to feedback the charging energy of a resonance condenser to an input DC power source with a control transformer. CONSTITUTION:The input terminals A, B of a control transformer 11 are connected to both ends of a resonance condenser 7, the output terminals C, D are connected to zero input side of a rectifier 12, and control terminals E, F are connected to the output side of a DC current controller 14. The output side of the rectifier 12 is connected to an input DC power source 2. A DC current controller 14 supplies the DC current in response to the output signal from a comparator 13 to the control terminals E, F of the transformer 11. A distributor 15 generates a pulse train which is frequency-modulated in response to the output signal from the comparator 13, and which is distributed to the switching elements 3, 4. Charging energy stored in the condenser 7 is transmitted as discharging energy to the input DC power source 2 of a DC/DC converter through the transformer 11.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a series resonant DC-
This invention relates to a constant voltage power supply device using a DC converter.

Conventional switching regulator CL1 A PWM method is generally used to stabilize the output DC voltage by controlling the duty ratio of the on/off operation of the switching element. However, the disadvantage of the above method is that there is a period in which the current and voltage change sharply when the switching element is turned on and off, resulting in large switching losses and large unnecessary radiation noise. Therefore, if the above switching regulator is considered as a power supply for audio equipment, it is necessary to take noise countermeasures such as inserting a filter in the input/output section to greatly attenuate unnecessary radiation noise, and applying a completely sealed shield. Therefore, there are problems such as increased cost and decreased reliability.

As a means to solve the above drawbacks, a series resonant DC-DC converter using a series resonant circuit composed of a capacitor and a coil is proposed.
DC converters have been proposed.

In this series resonant DC-DC converter, due to the series resonant circuit, the current waveform when the switching element is conductive becomes a sine wave, and the current and voltage intersect at zero when the switching element is turned on and off. Therefore, switching loss and unnecessary radiation noise are significantly reduced. However, in the series resonant DC-DC converter, it is difficult to control input/output fluctuations to stabilize the output DC voltage without impairing the above characteristics.

Based on the above points, the conventionally used series resonant type D
The circuit configuration and operation of the C-DC converter will be explained.

Figure 1 is a basic circuit configuration diagram of a conventional series resonant DC-DC converter, and Figures 2 (a), (b), (C
) is its operating waveform diagram. In FIG. 1, switching elements (for example, transistors, thyristors, etc.) 3 and 4 that perform on/off operations are connected in a 1h column between both terminals of two input DC power supplies 1 and 2 connected in series, A resonance capacitor 7 and a primary winding 5a of a conversion transformer 6 are connected in series between the input DC power supplies 1 and 2 and the switching elements 3 and 4. Further, a rectifier circuit 8 and a smoothing capacitor 9 are connected to the secondary winding 5b of the conversion transformer 6, and a load 10 is connected to its output terminals a and b. Here, it is assumed that the resonant current flowing in the series resonant circuit composed of the resonant capacitor 7 and the effective leakage inductance of the conversion transformer 5 is ^, and the charging voltage of the resonant capacitor 7 is vo. Figure 2 (,), (b).

(C) shows the on/off states of the switching elements 3 and 4;
The above resonance current and charging voltage V. The operating waveform diagram is shown.

In FIG. 2, the switching element 3 is turned on at time t1, and the resonance current becomes a sinusoidal current whose period is determined by the capacitance of the resonance capacitor 7 and the effective leakage inductance between time t1 and time t2. During the above period, the charging voltage V. is V due to the resonant current from the initial charging voltage -vcl. It becomes 1.

Next, at time t2, switching element 3 is turned off. Time t2≦tit. between switching element 3
, 4 are off, the resonant current becomes zero, and the charging voltage V of the resonant capacitor 7. 1 also remains constant since there is no discharge path. When the switching element 4 is turned on at time t3, the operating waveform is opposite in positive and negative to the operating waveform during time t1≦t≦t3, and thereafter, the switching element j is turned on again.
When turned on, the same operation repeats. Further, the resonant current t is transmitted to the secondary side via the conversion transformer 6, and after rectification and smoothing, is supplied to the load 1o as a predetermined output DC voltage 7.

The above is the circuit configuration and operation of the conventional series resonant type DC-DC converter.As a means for controlling the series resonant type DC-DC converter, the capacitance value of the resonant capacitor 7 is controlled. Switching element 3
, 4 is proposed to control the off-state period, that is, the switching frequency. However, in either case, the amount of resonant current does not change, making control difficult.

The present invention is a constant voltage power supply device that stabilizes the output DC' voltage over a wide range of input/output fluctuations without impairing the characteristics of the resonance system. This is what we are trying to provide.

The present invention will be described below, but first a control transformer having a variable inductance function used in the present invention will be described. FIG. 3 is a schematic configuration diagram showing an example,
Fig. 4 is a characteristic diagram thereof, and Fig. 6 is a diagram showing its symbols. In Fig. 3, AC windings Na, Nb, Nc, and Nd are provided on each leg of a combination of an E-type core and an I-type core, or a combination of two E-type cores, and a DC winding is provided on the central leg. A DC current source I is connected between the control elements E and F of the DC winding Ne. Also, A.

B is an input terminal, and C and D are output terminals. The AC windings Na and Nb are connected in series to form a first winding, and are wound in such a way that the magnetic flux induced in the center leg by the AC currents from the input terminals A and B is canceled out. That is, the magnetic flux φ2. induced by the AC windings Na, Nb. This is a state in which φm is equal. Furthermore, AC windings Nc and Nd are connected in series to form a second winding, and output terminals C and D are connected in series to form a second winding.
It is connected to the AC windings Na and Nb at a constant turns ratio.

Here, by flowing a DC power from the DC power supply I, a magnetic flux φ1 is generated in the DC winding Ne, and the inductance between the input terminals A and B changes. Input terminals A and B with direct current
Figure 4 shows the change in inductance between the two. Therefore, due to the direct current flowing between control terminals E and F, input terminal A
, B to control the inductance between them in a decreasing direction, force 1
Becomes Ding Noh. FIG. 6 shows the symbols of the control transformer described above, and embodiments of the present invention using this will be described below with reference to the drawings after FIG. FIG. 6 is a circuit diagram of the first embodiment of the present invention, in which components having the same functions as those explained in FIG. 1 are given the same reference numerals. Figure 7 (a), (b), (C)
.

(d), (e), and (f) are operation waveform diagrams in FIG. 6.

In FIG. 6, 11 is a control transformer as illustrated in FIG. 3, 12 is a rectifier circuit, 13 is a comparison circuit, 14 is a DC current control circuit, and 16 is a distribution circuit. Input terminal A of the control transformer 11.

B is connected to both ends of the resonance capacitor 7, the output terminal C2D is connected to the input side of the rectifier circuit 12, and the control terminals E and F are connected to the output side of the DC current control circuit 14.

Further, the output side of the rectifier circuit 12 is connected to the input DC power source 2. The comparator circuit 13 has DC output voltages of output terminals a and b applied to its input terminals.

The values of a predetermined reference voltage E8 are compared and a difference signal is supplied to a DC current control circuit 14 and a distribution signal to a circuit 16. The DC current control circuit 14 controls the DC current according to the output signal from the comparison circuit 13 to the control terminal E of the transformer 11,
By supplying F.

It constitutes a first control means that changes the inductance between input terminals A and B (first winding) of the control transformer 11. Also, the distribution is as follows for circuit 16.

A frequency-modulated pulse train is generated according to the output signal from the comparison circuit 13, and this is transmitted to the switching elements 3 and 4.
It is distributed and supplied and turned on alternately.

It constitutes a second control means for turning off.

Next, the principle of operation of the embodiment shown in FIG. 6 will be explained with reference to FIG. 7. However, explanations that overlap with those of the conventional example will be omitted. The period of the resonant current flowing through the resonant circuit is determined by the effective leakage inductance of the conversion transformer 6 and the inductance between the input terminals A and B of the resonant capacitor 7 and the control transformer 11. Further, the control current 2L1 flowing between the input terminals A and B of the control transformer 11 becomes a continuous sine wave, and the charging voltage of the zero resonance capacitor 7, which is synchronized with the resonance current -, is proportional to the sum of the resonance current and the control current AL1. increases. -] The double bending state is from time t1 when the switching element 3 is turned on to time t:l. At time tj, the voltage induced at the output terminals C and D of the control transformer 11 becomes higher than the voltage of the input DC power supply 2, and the charging energy stored in the resonance capacitor 7 becomes
The discharge energy is transmitted via the control transformer 11 to the human-powered DC power supply 2 of the DC-DC converter. This state is from time t' to time t6. Further, the output current iL2 of the control transformer 11 flowing during the above period becomes a sine wave, and its period is determined by the capacitance of the resonance capacitor 7 and the inductance of the control transformer 11. As a result of the above phenomenon, the charging voltage V of the resonance capacitor 7 increases. is vc4 due to the flow of the output current LL2 of the control transformer 11.
(Time t'2) It drops at the trench and the next switching element 4
At time t3t when is turned on, the control current LL1 turns V.

It decreases at 2 trenches. Thereafter, the polarity is reversed as a phenomenon from time t3 to time t6, and when the switching element 3 is turned on at time t6, the waveform becomes exactly the same from then on, and the same phenomenon is repeated.

Moreover, the factor that determines the current amount of the resonance current - is the initial charging voltage V of the resonance capacitor 7. Therefore, by changing the value of the initial charging voltage, 2
The amount of current transmitted to the next side changes, and the energy supplied to the output terminals a and b of the DC-DC converter can be controlled. Initial charging voltage V. are -vo2 at time t1 and V at time t in FIG. The initial charging voltage (-Vo23 c2, vC2) is related to the output current "L2" of the control transformer 11 as described above, and the amount of the output current LL2 of the control transformer 11 is also related to the control current LL1. Therefore, in order to change the output DC voltage, it is sufficient to control the current amount of the control current LL1 to be changed.In other words,
The amount of current of control current AL1 is.

The present invention utilizes the fact that the inductance between the input terminals A and B of the control transformer 11 is inversely proportional to the inductance, and the switching frequency of the switching elements 3 and 4 is also inversely proportional to the inductance.

FIG. 8 shows a second embodiment of the present invention, and FIG. 9 shows its operating waveforms. In this embodiment as well, parts having the same functions as those explained in FIG. 6 are given the same reference numerals. In this embodiment, the diodes 16 and 17 are connected to the switching elements 3 and 4 so as to conduct in the opposite direction to the conduction direction of the switching elements 3 and 4, that is, to be reverse biased with respect to the input DC power supplies 1 and 2. By connecting them in parallel, the charging energy stored in the resonance capacitor 7 is transferred to the input DC power source 1 or 2 as regenerative energy through the diode 16 or 17. The operation will be explained below with reference to FIG. Note that the operation in which the output current LL2 from the control transformer 11 flows is exactly the same as that in the first embodiment shown in FIG. 6, so a description thereof will be omitted here.

In FIG. 9, the time t when the switching element 3 turns off
At 2 o'clock, the charging energy stored in the resonance capacitor 7 is transferred from the resonance capacitor 7 to the conversion transformer 6. It is regenerated as a regenerative current to the input DC power supply 1 via the diode 16. The above phenomenon occurs during the period from time t2 to time v- in the waveform diagram of the resonant current shown in FIG. 9(C). Therefore, the initial charging voltage V of the resonance capacitor 7 determines the resonance current. 6 (time 13) changes greatly depending on the output current "L2" of the control transformer 11 and the above-mentioned regenerative current. After that, during the period from time t3 when the switching element 4 is turned on to time t6, the polarity reverse phenomenon is repeated, and furthermore, the time When the switching element 3 is turned on at t6, the operating waveform becomes the same as that from time t1.The control operation is performed in exactly the same manner as in the embodiment shown in FIG. 6.The connection points of the diodes 16 and 17 are The series connection circuit between the switching element 3 and the primary winding 6a of the conversion transformer 6, and the series connection circuit between the switching element 4 and the primary winding 6a of the conversion transformer 6, are not limited to those shown in the drawings. They may be connected in parallel, and similar effects can be obtained even in this case.

FIG. 10 shows a third embodiment of the present invention. Also in FIG. 10, parts having the same functions as those explained in FIG. 3 are given the same reference numerals.

In Figure 10, 18.19 are diodes, 2°, 2
The regenerative coils connected in series to the diodes 18 and 19 are connected to the primary winding 6a of the conversion transformer 5 and the switching element 1, respectively. , 4 are connected in parallel to each of the four series-connected circuits.

Note that each diode 18 and 19 is connected to the switching element 3.
. The operating principle of this embodiment is the same as that of using the regenerative current from the resonance capacitor 7 described in the second embodiment shown in FIG. The diode and regenerative coil (18 and 20 trenches are connected in series) without going through the conversion transformer 6.
9 and 21) to the input DC power source 1 or 2, the difference is that it does not become the output energy of the DC-DC converter. Furthermore, regenerative coil 2o or 21
By changing the inductance of the regenerative current Ld1'
It is also possible to arbitrarily change the period of d2. The control operation is completely similar to the embodiments shown in FIGS. 6 and 8.

In each of the embodiments of the present invention described above, a configuration has been described in which the charging energy of the resonant capacitor 7 is fed back to one of the input DC power sources 2 using the control transformer 11. A similar effect can be obtained by feeding back to the entire input DC power supplies 1 and 2 connected to the input DC power supplies 1 and 2. Further, in each of the embodiments of the present invention described above, a half-bridge configuration using two switching elements is used, but a full-bridge configuration using four switching elements can also be implemented, and similar effects can be obtained. It will be done. Furthermore, although the effective leakage inductance of the resonant capacitor and the conversion transformer is used to form the series resonant circuit in the present invention, a resonant coil is connected in series with the primary winding of the resonant capacitor and the conversion transformer. It goes without saying that a series resonant circuit using the inductance of a resonant coil is also possible, and is included in the present invention.

As described above, according to the present invention, with a simple circuit configuration,
It is capable of stabilizing the output DC voltage under a wide range of input/output fluctuations while taking advantage of the features of the series resonant DC-DC converter, and its industrial value is extremely high1.

[Brief explanation of the drawing]

Figure 1 is a circuit configuration diagram of a conventional series resonant DC-DC converter, Figures 2 (a), (b), and (C) are its operating waveform diagrams, and Figure 3 is used in the present invention. A schematic diagram showing a configuration example of a control transformer, FIG. 4 is its characteristic diagram, FIG. 6 is its equivalent symbol diagram, FIG. 6 is a circuit configuration diagram of the first embodiment of the present invention, and FIG. 7 (a) , (b), (c),
(d), (e). (f) is its operation waveform diagram, FIG. 8 r [Circuit configuration diagram of the second embodiment of the present invention, FIG.
c), (d), (e). (f) is an operating waveform diagram thereof, and FIG. 10 is a circuit configuration diagram of a third embodiment of the present invention. 1.2...Input DC power supply, 3,4...
Switching element, 5... Conversion transformer, 6a
...Primary winding, 5b...Secondary winding, 7
...Resonance capacitor, 8...-- Rectifier circuit, 9-- Sliding capacitor, 10... Load, 11... Control body Kunsu, 12...
Rectifier circuit, 13... Comparison circuit, 14...
・DC current control circuit, 16φ...---The distribution is the circuit,
16, 17, 18, 19・@-・・Evening. Iode, 20, 21... Regeneration coil. Name of agent: Patent attorney Toshio Nakao and 1 other person11
Figure 2 Figure 3 J → Figure 6 Accuracy Figure 7 --□ Eye Figure 8 Time (1)

Claims (1)

[Scope of Claims] O) A series connection circuit including at least a switching element that operates on and off, a primary winding of a conversion transformer, and a resonant capacitor is connected to an input DC power supply,
When a first rectifier circuit and a smoothing circuit are connected to the secondary winding of the conversion transformer and a DC output voltage is obtained at the output terminal.
a pC-DC converter configured as above, a first winding connected in parallel to the resonant capacitor, and a second winding for output extraction; a control transformer capable of changing the inductance of a winding; a second rectifier circuit that rectifies a signal voltage obtained from a second winding of the control transformer and supplies the rectifier to the input DC power supply; and the DC-DC converter. a first control means for controlling the inductance of the control transformer as a function of the DC output voltage available at the output terminal of the DC-DC converter; and a switching frequency of the switching element as a function of the DC output voltage available at the output terminal of the DC-DC converter. 1. A constant voltage power supply device comprising second control means for controlling (or cycle). @) A constant voltage power supply device according to claim (1), characterized in that a unidirectional element is connected in parallel to the switching element so as to conduct in a direction opposite to the conduction direction of the switching element. 0(3) In the description of claim (1), a coil and one unidirectional element that conducts in the opposite direction to the conduction direction of the switching element are connected in four rows & the circuit is A constant voltage power supply device i''Io is characterized in that it is connected in parallel to a series connection circuit of a switching element -r and a primary winding of a conversion transformer.