JP2629999B2 - DC / DC converter series connection circuit - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a series connection circuit of DC / DC converters constituting a DC power supply circuit for converting a relatively high DC voltage to a low DC voltage.

[Conventional technology]

As a conventional series connection circuit of this type of DC / DC converter, one disclosed in Japanese Patent Application Laid-Open No. 62-260560 is known.
FIG. 2 and FIG. 3 are circuit diagrams showing a series connection circuit of such DC / DC converters.

FIG. 2 is a circuit diagram in a case where two identical DC / DC converters each having a switching element as a transistor are connected in series to a DC power supply to obtain four sets of insulated secondary DC voltages. DC power source, 2 a discontinuous portion of the respective DC / DC converters and _{3, T 21, T 22,} T 31, T 32 is the switching _{transistor, D 21, D 22, D} 31, D 32 is power regeneration diode, C _21, C ₃₁ is the drive circuit for the smoothing capacitor, and 2a and 3a and the transistor T _21, T ₂₂ and T _31, T _32, respectively, common control circuits for the respective switching transistors 4, the 5a and 6a is The output transformers receive DC interrupted voltages from the DC / DC converter interrupting sections 2 and 3, respectively, and their secondary coils are connected in parallel with the same polarity as indicated by ● in the figure. Each 5b and a 6b the transformer 5a and 6a and the common secondary voltage receiving required insulated pair of the second order direct-current voltage 2 sets of branching transformer outputting an AC voltage corresponding to, D ₁ ~ D ₄ is a diode for half-wave rectification, C ₁
-C ₄ the smoothing capacitor, 7-10 is the load resistance. The parallel connection of the secondary coils of the two output transformers 5a and 6a is connected to the DC / DC converter intermittent section 2 due to load imbalance or the like.
And 3 for forming an energizing path of the return current for correction when the output voltage characteristics of the circuits 3 and 3 are unbalanced.

Next, FIG. 3 shows each of the transformers 5a and 5b shown in FIG.
6a and 6b are combined into output transformers 5c and 6c, respectively, and four sets of secondary coils are provided for each of the transformers. Each pair of the secondary coils of both transformers is connected in parallel with the same polarity via a diode. connect, is obtained to obtain a desired insulated four sets of secondary DC voltage via respective from the resulting four sets of parallel connection the smoothing capacitor C ₁ -C _4.

Note that when the respective secondary coils of the respective output transformers are connected directly or in parallel via a diode, the operation of balancing the output voltage characteristics of the DC / DC converter intermittent part and the DC / DC converter
Regarding the details of the DC power transformation transmission operation by the combination of the converter intermittent part and the output transformer, refer to Japanese Patent Laid-Open No.
It is as shown in the 0560 publication.

[Problems to be solved by the invention]

However, as described above, a plurality of DCs connected in series by the parallel connection of the output transformer secondary coil of the DC / DC converter
In the conventional circuit that balances the output voltage characteristics of each DC / DC converter, in order to obtain the required insulated secondary DC voltage, the type and number of required transformers or the number of transformer coils must be increased. As the required output capacity increases due to the use of windings, the required transformers become larger and more specialized, causing noise between windings and lowering the disconnection characteristics. As a result, the DC power supply becomes large. This has led to higher prices.

In view of the above, the present invention provides each DC / D converter in the output transformer.
DC / D that can be downsized and cost-effective as a DC power supply by magnetically synthesizing the output voltage of the C converter intermittent section
The purpose is to provide a series connection circuit of C converters.

[Means for solving the problem]

To achieve the above object, the DC / DC converter series connection circuit of the present invention connects both ends of a primary coil of a transformer to a DC power supply via separate semiconductor switching elements connected in the same conduction direction. A DC / DC converter comprising a plurality of identical DC / DC converters connected in series so as to extract power from a secondary coil of the transformer by simultaneously turning on / off each of the semiconductor switching elements.
A series connection circuit of converters, wherein the primary coils of the transformer in each of the DC / DC converters are formed as a plurality of insulated primary coils of an output transformer in which the primary coils are arranged on the same magnetic path with the same polarity. An appropriate number of insulated secondary coils are provided on the secondary side of the transformer, and a required number of insulated secondary coils are respectively insulated from each of the secondary coils via a rectifier and a smoothing capacitor.
To obtain the next DC voltage.
When the required number of the next DC voltages increases, a plurality of the output transformers are provided according to the required number, and the primary coils of the respective output transformers are connected in parallel with the respective DC / DC converters, respectively. A required number of secondary DC voltages insulated via a rectifier and a smoothing capacitor are obtained from each of the secondary coils of each of the output transformers.

[Action]

In a transformer having a plurality of primary coils of the same polarity and a plurality of secondary coils of the same polarity, the voltage shared by each of the coils is a temporal change rate of a magnetic flux in an iron core according to a sum of magnetomotive forces generated by the coils, and its winding. It is determined as the proportional value of the product of numbers.
Therefore, for example, the output voltage of each of the secondary coils at the time of occurrence of unbalanced fluctuation between the input voltages on the primary side varies at the same ratio according to the respective turns ratio via the magnetic flux in the iron core. When the load imbalance of the secondary coil occurs, the shared voltage of each primary coil also fluctuates at the same ratio according to the respective turns ratio. That is, as described above, by sharing the iron core of each primary coil having a different power supply, the balance of each output voltage on the secondary side at the time of unbalance fluctuation of each input voltage at the primary side and the balance at the time of occurrence of unbalance of each load on the secondary side The balance of each primary coil sharing voltage can be maintained.

The present invention applies each of the primary-side input voltages as respective intermittent output voltages of a plurality of DC / DC converters connected in series to respective primary coils sharing a transformer core.
The secondary voltage is a value corresponding to a plurality of required secondary DC voltages in its half-wave rectified value, and equalization of the shared voltage of each primary coil due to occurrence of unbalance in each secondary load. ,
Therefore, it is intended to equalize the input / output both-side shared voltage of each of the DC / DC converter intermittent sections.

〔Example〕

An embodiment of the present invention will be described below with reference to the circuit diagram shown in FIG.

FIG. 1 shows a combination of the output transformers 5a and 6a and the branching transformers 5b and 6b in FIG. 2 with a primary coil and a secondary coil each wound in the same polarity and composed of two sets. The output transformers are replaced with output transformers 5 and 6 arranged on the same iron core, and the primary coils of the transformers 5 and 6 are connected in parallel with the same polarity for each corresponding coil. The output voltages of the / DC converter intermittent units 2 and 3 are applied respectively.

In the circuit configuration as described above, when an unbalanced change occurs in the loads 7 to 10, the magnetic flux in the iron core of the output transformer 5 or 6 to which the variable load is connected fluctuates and interlinks with the magnetic flux.
The shared voltage of the four sets of secondary and secondary coils changes at the same ratio, and further changes the magnetic flux in the iron core of the other output transformer 5 or 6 via the primary coil connected in parallel to link the magnetic flux. The primary voltage and the secondary voltage of the four sets are changed. Such fluctuations are terminated when the magnetic fluxes in the iron cores of the two output transformers 5 and 6, that is, the shared voltages of the primary and secondary coils linked to the two magnetic fluxes reach an equilibrium state, respectively. The installation of a plurality of output transformers as shown in FIG. 1 is determined according to the required number of secondary DC voltages.
The operation of automatic balancing of the voltage sharing in the series connection of the C converters is performed based on the composite magnetic flux in the single transformer core connected to the configuration such as the output transformer 5 or 6 and the circuit.

〔The invention's effect〕

According to the present invention, each of the primary coils of the output transformer in which a plurality of primary coils are arranged on the same iron core with the same polarity applies the output voltage of each intermittent portion of the DC / DC converter connected in series to the primary coils. In addition, by obtaining a required output voltage from a plurality of secondary coils arranged with the same polarity on the iron core, both input and output sides of each of the DC / DC converter interrupted portions against unbalance fluctuation of a secondary circuit load. The automatic balancing operation of the shared voltage is performed, the type and number of required transformers for the balancing can be reduced, the structure can be simplified, and the DC power supply can be reduced in size and cost. .

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing an embodiment of the present invention, and FIGS.
1 is a circuit diagram showing an embodiment of the prior art. 1 ... DC power supply, 2,3 ... DC / DC converter intermittent part, 2a, 3
a ... Drive circuit, 4 ... Control circuit, 5,5a, 5c, 6,6a, 6c ...
Output transformer, 5b, 6b ...... branch transformer, 7-10 ...... load _{resistor, C 1 ~C 4, C 21} , C 22 ...... smoothing capacitor, D ₁ to D _4,
D ₂₁ , D ₂₂ , D ₃₁ , D ₃₂ …… Diode, T ₂₁ , T ₂₂ , T ₃₁ , T ₃₂ ……
Switching transistor.

Claims (2)

(57) [Claims] 1. The method according to claim 1, wherein both ends of a primary coil of the transformer are connected to a DC power supply via separate semiconductor switching elements connected in the same conduction direction, and the semiconductor switching elements are simultaneously turned on and off. In a DC / DC converter series connection circuit in which a plurality of identical DC / DC converters configured to extract power from a secondary coil of a transformer are connected in series, a primary coil of the transformer in each of the DC / DC converters is provided. Are formed on the same magnetic path in a plurality of insulated primary coils of an output transformer arranged in the same polarity, and an appropriate number of 2 coils insulated on the secondary side of the output transformer.
A series connection circuit of DC / DC converters, wherein a secondary coil is provided, and a required secondary DC voltage isolated from each of the secondary coils via a rectifier and a smoothing capacitor is obtained. 2. The DC / DC converter series connection circuit according to claim 1, wherein when the required number of said secondary DC voltages increases, a plurality of said output transformers are provided according to said required number. The required number of secondary DCs are connected in parallel with the primary coils of the transformers in correspondence with the respective DC / DC converters, and are insulated from the respective secondary coils of the respective output transformers via rectifiers and smoothing capacitors. A DC / DC converter series connection circuit characterized in that a voltage is obtained.