JP2001078449A - Dc power supply unit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce ripples of an output current, and balance current passing through a plurality of series resonance switching power sources using a simple structure, when the plurality of series resonance switching power sources are connected in parallel. SOLUTION: Respective series resonance switching power sources PU1-PU3 forming a DC power supply unit are connected in parallel, and reactors L12, L22, L32 for balancing current connected in parallel with the primary windings N11, N21, N31 of respective transformers T are coupled electromagnetically to switch the respective DC resonance switching power source PU1-PU3, so as to provide phase difference at equal intervals respectively. A s a result, the ripples of the output current of the DC power supply unit, and balance the current in the respective switching power sources are reduced, thereby miniaturizing the DC power supply unit. By providing a detection winding for the reactor, whether any of the power sources is in failure is detected.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a DC power supply in which a plurality of series resonant switching power supplies are connected in parallel.

[0002]

2. Description of the Related Art In general, a resonance type switching power supply uses a resonance circuit to make a voltage or current applied to a switching transistor into a sine wave shape, and makes the voltage or current at the moment when the switching transistor is turned on or off zero. The power loss of the switching transistor is greatly reduced.

As a switching element of such a resonance type switching power supply, a high-performance FET type is used in recent years.

For example, in a conventional DC power supply device in which a plurality of series-resonant switching power supplies are connected in parallel, it is common to operate a plurality of switching power supplies in the same phase by frequency control.

[0005]

However, in order to operate a plurality of switching power supplies in the same phase, there is a problem that the ripples of the outputs of the respective switching power supplies are superimposed in the same phase, and the ripple current becomes large.

Further, there is a problem that a difference occurs in currents flowing through the switching power supplies due to variations in elements constituting each switching power supply, and as a result, a desired voltage output cannot be obtained.

In addition, since the resonance type switching power supply controls the frequency, it is difficult to balance the currents with each other. Therefore, in a large-capacity DC power supply,
There was a problem that miniaturization was hindered.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems. In a DC power supply device in which a plurality of series resonance type switching power supplies are connected in parallel, a ripple of an output current is reduced and a plurality of series resonance type The current flowing through the switching power supply is balanced by a simple configuration.

[0009]

According to the first aspect of the present invention, there is provided a DC power supply, and switching means for switching a DC from the DC power supply to convert the DC power into an AC power, comprising a switching element.
DC means for rectifying and smoothing AC, series resonance means formed in series with a current balance reactor between the output end of the switching means and the DC means, and switching elements turned on with a dead time. A DC power supply device in which a plurality of series-resonant switching power supplies having control means for turning off are connected in parallel.

[0010] Each reactor of the plurality of series resonant switching power supplies is connected in series to the primary winding of a transformer and is electromagnetically coupled to each reactor of each of the other series resonant switching power supplies. And

A second aspect of the present invention is that each control means of each series resonance type switching power supply controls a switching element of the series resonance type switching power supply with a phase difference at equal intervals.

According to a third aspect of the present invention, a detection winding electromagnetically coupled to each reactor of each series resonance type switching power supply is provided, and means for detecting the presence or absence of a voltage signal induced in the detection winding is provided. Make a summary.

[0013]

FIG. 1 is a schematic configuration diagram of a DC power supply according to the present embodiment. In this DC power supply device, series resonant switching power supplies PU1, PU2, and PU3 are connected in parallel with each other.

[0014] series resonant switching power supply PU1 has an input terminal 2a for DC source 1 is connected to both ends of the input smoothing capacitor _{C 11} to 2b.

Further, connected in parallel to the input smoothing capacitor _{C 11} and the current resonance capacitor _{C 12} and the current resonance capacitor _{C 13} connected in series.

The FET type transistor Q₁₁(Less than
Simply switching element Q₁₁) And FET type transformer
Jista Q₁₂(Hereinafter simply referred to as switching element Q₁₂To
And the input smoothing capacitor C₁₁,
Current resonance capacitor C₁₂, C ₁₃Connected in parallel
You.

Further, the voltage resonance capacitor _{C 14} is provided in parallel with the switching element _{Q 11,} a voltage resonance capacitor _{C 15} are provided in parallel with the switching element _{Q 12.}

Furthermore, one end of the switching element _{Q 11} of the primary winding _{N 11} of the transformer _{T 1} and the switching element Q
It is connected to the ₁₂ connection points a, and the primary winding _{N 1 1} of the other end the current resonant reactor _{L 11} of the transformer _{T 1,} the current resonance capacitor _C 12 through the reactor _{L 12} for current _{balance, C 13} Is connected to the connection point b.

Furthermore, one end of the secondary winding _{N 12} of the transformer _{T 1} is connected to the rectifier diode _{D 11,} a secondary winding N
The other end of ₁₂ is connected to the rectifier diode _{D 12.}
Cathode and cathode of the rectifier diode D ₁₁ of the commutation diode D ₁₂ is connected in common. That is, the secondary side of the transformer T ₁ is the forward system.

Further, one end of the output smoothing capacitor _{C 16} is the rectifier diode is connected to the cathode of _{D 11,} the other end of the output smoothing capacitor _{C 16} is connected to the neutral point c of the secondary winding _{N 12.}

Furthermore, a a reactor _{L 13} for output and the output smoothing capacitor _{C o} are connected in series are connected in parallel to the output smoothing capacitor _{C 16.}

Further, an output terminal 5a smoothing capacitor _{C o,} and connected to one end of the _{C 16,} and connects the output terminal 5b to the connection point d of the output smoothing capacitor _{C o} and the reactor _{L 13.}

On the other hand, the series resonance type switching power supply PU1
Series switching power supply PU connected in parallel to
2. The configuration of PU3 is a series resonance type switching power supply PU1.
However, in order to distinguish between them, circuit components are prefixed with “2” in the serial resonance type switching power supply PU2 and “2” is added in the series resonance type switching power supply PU3. Is added to "3". However, the series resonance type switching power supply PU2,
PU3 the reactor _{L 13} for the output is not is provided.

The series resonance type switching power supply PU
2, inputs the one end of the input smoothing capacitor _{C 21} terminals 2a
And commonly connected to one end of the input smoothing capacitor C ₁₁ of the series resonant type switching power supply PU1, and the other end of the input smoothing capacitor C ₁₁ of the input smoothing input and the other end of the capacitor C ₂₁ terminals 2b and series resonant switching power supply PU1 Common connection. Also, the series resonant switching power supply PU2 are commonly connected to one end of the output smoothing capacitor _C 16, _{C O} of the output smoothing output end terminals 5a and series resonant switching power supply PU1 of the capacitor _{C 26,} and output smoothing capacitor _{C 26} Is connected to the output terminal 5b and the output smoothing capacitor C of the series resonance type switching power supply PU1.
_The common power supply ₁₆ is connected in parallel to the other end of the switching power supply PU1.

Further, a series resonance type switching power supply PU
3 is an input smoothing capacitor C₃₁Of the input terminal 2a
And input smoothing capacitor of series resonance type switching power supply PU1
Densa C₁₁And one end of the series resonance type switching power supply P
U2 input smoothing capacitor C ₂₁Common connection with one end of
And the input smoothing capacitor C₃₁Input terminal 2
b and the input smoothing capacitor of the series resonance type switching power supply PU1.
Capacitor C₁₁The other end and a series resonant switching power supply
PU2 input smoothing capacitor C₂₁To the other end of the
ing. Further, the series resonance type switching power supply PU3 includes:
Output smoothing capacitor C₃₆Is connected to the output terminal 5a
Output smoothing capacitor of column resonance type switching power supply PU1
C₁₆, C_OAnd one end of the series resonance type switching power supply P
U2 output smoothing capacitor C₂₆Common connection with one end of
Output smoothing capacitor C₃₆Output terminal 5
b and the output smoothing capacitor of the series resonance type switching power supply PU1.
Capacitor C₁₆The other end and a series resonant switching power supply
PU2 output smoothing capacitor C ₂₆Common connection with other end of
By doing so, the series resonance type switching power supply PU1
And a parallel connection to the series resonance type switching power supply PU2.
Has continued.

Further, a current balance reactor L
_{12, L 22} and _{L 32} are each of the core are connected in common. That is, the same induced current flows in each case.

The operation of the DC power supply configured as described above will be described below with reference to the waveform diagram of FIG.

The series resonant switching power supplies PU1, PU
2 and PU3 switching element Q ₁₁, Q₁₂, Sui
Switching element Q₂₁, Q₂₂, Switching element
Q₃₁, Q ₃₂Is dead as shown in FIGS. 2A and 2B.
Turn on alternately with time.

(1) Series resonant switching power supply PU1
(A) Switching element Q₁₁Description of ON period Switching element of series resonance type switching power supply PU1
Q₁₁Is on, the DC input terminal 2a, the switch
Element Q₁₁, Primary winding N₁₁, Reactor L ₁₁,
Reactor L for flow balance₁₂, Capacitor C
_13,Circuit route and capacitor for DC input terminal 2b
Sa C₁₂, Switching element Q₁₁, Primary winding N₁₁,
Reactor L₁₁, Reactor L for current balance₁₂
2E, the current having the waveform shown in FIG.
I_DQ₁₁Flows.

This current I_DQ₁₁Is the primary winding N₁₁When
Reactor L₁₁And capacitor C ₁₂, C₁₃Directly with
This is a current based on column resonance. The current I_DQ
₁₁Is a waveform approximating a sine wave,
Indicates that a zero current switch is enabled
You.

The switching element Q₁₁Is on
Between the transformer T₁Secondary winding N ₁₂, Diode D
₁₁, Capacitor C₁₆Output current I₀₁
You will get

[0032] (b) Description of the period when the switching element _{Q 11} is turned off from on next period when the switching element _{Q 11} is turned off from on (dead time), the DC input terminal 2a, a capacitor _{C 14,} primary winding Line N ₁₁ , reactors L ₁₁ , L ₁₂ ,
Capacitor _{C 13,} the circuit route and the primary winding _{N 1 1} DC input terminal 2b, the reactor _{L 11, L 12,} current flows through the circuit route of the capacitor _{C 13, C 15,}
Figure 2 voltage _V DS _{Q 11} of _{Q 11} is changed as shown in (C), the zero volt switching transistor _{Q 11} is achieved. This voltage _V DS _{Q 11} is based on the resonance of the primary winding _{N 11} and the reactor _{L 11} and capacitor _{C 14, C 15.}

[0033] (c) Operation series resonant period switching element _{Q 12} is on the switching power supply PU1 the period of the switching element _{Q 12} is turned on, the DC input terminal 2a, a capacitor _{C 12,} inductor _{L 12} for current balance, Reactor L ₁₁ , primary winding N ₁₁ , switching element Q ₁₂ ,
Circuit route and the capacitor _{C 13} of the DC input terminal 2b, the reactor _{L 12} for the current balance, the reactor _{L 11,} primary winding _{N 11,} the circuit route of the switching elements _{Q 12,} current waveform shown in FIG. 2 (F) I
_D Q ₁₂ flows.

The switching element Q₁₂Is on
Between the transformer T₁Secondary winding N ₁₂, Diode D
₁₂, Capacitor C₁₆Output current I₀₁
You will get

The (d) The switching element _{Q 12} is turned off from the ON period of description DC input terminal 2a, a capacitor _{C 12,} inductor _{L 12} for the current balance, the reactor _{L 11,} primary winding N
_11, capacitor _{C 15,} the circuit route and the primary winding _{N 11} of the DC input terminal 2b, the capacitor _{C 14,} a capacitor _{C 12,} balance reactor _{L 12,} reactor L
By ₁₁ circuit route, current flows, the voltage _V DS _{Q 12} of the switching element _{Q 12} is changed as shown in FIG. 2 (D).

The series resonant switching power supplies PU2 and P
The operation of U3 is based on the series resonant switching power supply PU1.
The description is omitted because it is almost the same as.

The series resonant switching power supplies PU1, PU
2.PU3 switches with 2π / 3 phase difference respectively
Reactors for performing operations and balancing each other's current
L₁₂, L ₂₂, L₃₂By passing the same current through
The power in the series resonant switching power supplies PU1 to PU3
Balance the flow and reduce the output ripple
I have to.

The reason will be described with reference to FIGS.
For example, if the core between the balancing reactor L _{1 2} ~L ₃₂ is not connected in common, current I ₃ is the series resonant switching power supply PU1 and series resonant switching power supply which flows in series resonant switching power PU3 for some reason When large compared to the PU2, current I ₁ ~I ₃ flowing through the primary winding side of each transformer T ₁ is as shown in FIG.

[0039] However, in the present invention, since the core between the reactor L ₁₂ ~L ₃₂ for balancing are provided commonly connected, thus not.

[0040] That is explained with FIG 4 the status of the current at time t in FIG. 3, when the current I ₃ of the series resonant switching power PU3 increases, the voltage generated in balance reactor L ₃₂ of the power PU3 is Power supply PU
1, PU2, and PU3, the voltage direction is the direction shown in FIG. 4, and the power supply PU3 works as a voltage drop, and the power supplies PU1 and PU2 work as a voltage rise.

For this reason, each reactor (L ₁₂ , L ₁₂ ) of each series resonance type switching power supply PU 1, PU 2, PU 3
₂₂ , L ₃₂ ), the currents I ₁ , I ₂ , I ₃ are evenly balanced as shown in FIG.

Therefore, the total current I ₀ via the output smoothing capacitor C _o and the reactor L ₁₃ has a waveform with little ripple as shown in FIG.

FIG. 6 shows another embodiment, in which one of the series resonance type switching power supply PU1, the series resonance type switching power supply PU2, and the series resonance type switching power supply PU3 fails, and This is a method for detecting a state when the power supply to the power supply is stopped.

In this embodiment, as shown in FIG. 6, a balance detection circuit 10 including a reactor La and a resistor Ra is provided, and the reactor La of the balance detection circuit 10 is connected to each series resonance type switching power supply (PU1, PU1).
2, PU3) are electromagnetically coupled to each reactor _{L 12, L 22, L 32} of.

Therefore, for example, if any of the series resonant switching power supplies fails, the current cannot be balanced due to the failed switching power supply.
A voltage is generated in the reactor La of the balance detection circuit 10.

[0046] That is, by providing the balance detecting circuit 10, it is possible to detect the state of the current flowing through the reactor _{L 12, L 22, L 32} of each of the series resonant switching power supply.

[0047]

As described above, according to the first aspect, each current balancing reactor of a plurality of series-resonant switching power supplies constituting a DC power supply connected in parallel to each other is connected in series to the primary winding of a transformer. The current balance reactors are magnetically coupled to each other.

For this reason, the current flowing through each series resonance type DC switching power supply can be balanced, and the DC power supply can be downsized.

According to the second aspect of the present invention, the on / off control of each switching element of each series resonance type switching power supply is performed at an equal phase difference, thereby reducing the ripple of the output current of the DC power supply. Thus, the current flowing through each series resonance type DC switching power supply can be balanced.

According to the third aspect, a detection winding is provided in a reactor electromagnetically coupled to each reactor of each series resonance type switching power supply, and it is detected whether or not voltage is induced in this winding. , It is possible to detect whether any power supply has failed.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a DC power supply device according to the present embodiment.

FIG. 2 is a waveform diagram illustrating an operation of the DC power supply device according to the present embodiment.

FIG. 3 is an explanatory diagram for explaining the reason why a current balance is obtained.

FIG. 4 is an explanatory diagram for explaining the reason why current balance is obtained.

FIG. 5 is an explanatory diagram for explaining the reason why ripple is suppressed.

FIG. 6 is a schematic configuration diagram of a DC power supply device according to another embodiment.

[Explanation of symbols]

PU1 Series resonant switching power supply PU2 Series resonant switching power supply PU3 Series resonant switching power supply 1 DC source C ₁₁ input smoothing capacitor C ₁₂ current resonance capacitor Q ₁₁ switching element Q ₁₂ switching element C ₁₄ voltage resonance capacitor T ₁ transformer N ₁₁ primary winding L ₁₁ current resonance reactor

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Claims (3)

[Claims] A DC power supply, a switching element for switching a DC from the DC power supply and converting the DC power to an AC, a DC means for rectifying and smoothing the AC, and an output terminal of the switching means. A series resonance type switching power supply having series resonance means formed in series with a current balance reactor between the DC means and control means for turning on and off the switching element with a dead time. A plurality of DC power supply devices connected in parallel, wherein each reactor of the plurality of series resonant switching power supplies is connected in series to a primary winding of a transformer, and each reactor of each of the other series resonant switching power supplies. A DC power supply, wherein the DC power supply is electromagnetically coupled to each other. 2. The DC power supply device according to claim 1, wherein each control unit of each of the series resonance type switching power supplies controls a switching element of the series resonance type switching power supply with a phase difference at equal intervals. . 3. A system according to claim 2, further comprising: a detection winding electromagnetically coupled to each reactor of each of said series resonance type switching power supplies, and means for determining whether or not a voltage is induced in said detection winding. Item 3. The direct-current power supply device according to item 1 or 2.