JP2003284338A - Switching power unit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enhance power conversion efficiency regarding a composite resonant converter which is equipped with a current-resonant converter on a primary side. <P>SOLUTION: As the composite resonant converter on the primary side a partial voltage resonance circuit is combined with the current resonant converter, and for the secondary side a secondary partial voltage resonance circuit is constituted. Then, as regards an insulated converter transformer which transmits power from the primary side to the secondary side, a primary winding and a secondary winding are wound in specified winding widths using a U-U- shaped core, and also it is arranged so that the primary side and the secondary side may be closely coupled without forming a gap in the magnetic foot of the core. <P>COPYRIGHT: (C)2004,JPO

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention
Related to switching power supply circuits provided as power sources
It is. 2. Description of the Related Art As a switching power supply circuit, for example,
Live-back converter, forward converter, etc.
Is widely known that employs a switching converter
Have been. These switching converters are switches
Switching waveform is rectangular,
There is a limit to noise suppression. Also, due to its operating characteristics,
It is known that there is a limit to the improvement of power conversion efficiency
You. Therefore, the applicant of the present invention first described various resonant converters.
Various types of switching power supply circuits have been proposed.
Resonant converters can easily achieve high power conversion efficiency
In both cases, the switching operation waveform is sinusoidal,
Noise is realized. In addition, a relatively small number of parts
It also has the advantage that it can be configured. The circuit diagram of FIG. 7 has been previously proposed by the present applicant.
As prior art that can be configured based on the invention
Of the switching power supply circuit of FIG. In this figure
The basic configuration of the power supply circuit shown
Equipped with a self-excited current resonant converter as a converter
ing. In the power supply circuit shown in FIG.
Generates DC input voltage (rectified smoothed voltage Ei) from power supply
Rectifier circuit system, as shown in the figure, two
Slow recovery type rectifier diodes D1, D2 and two
By connecting the smoothing capacitors Ci1 and Ci2, the doubled voltage
A rectifier circuit is formed. This makes it connected in series
An AC input is applied to both ends of the two smoothing capacitors Ci1-Ci2.
Rectified smoothed voltage Ei corresponding to twice the level of input voltage VAC
Is obtained. This rectified and smoothed voltage Ei is supplied to a subsequent switch.
Supplied as a DC input voltage to the
You. [0005] The switching capacitor of the power supply circuit shown in FIG.
The barter is of the current resonance type and has two switches as shown in the figure.
Elements Q1 and Q2 are connected by half-bridge
I have. In this case, the switching elements Q1 and Q2
Is a bipolar transistor. Switch
The base of the switching element Q1 is connected to the base current limiting resistor.
Anti-RB1-resonance capacitor CB1-drive winding NB1 connected in series
A self-excited oscillation driving circuit is connected. Switchon
A damper diode is provided between the base and the emitter of the
The nodes DD1 are connected in the direction shown. Also,
During startup between the collector and base of the switching element Q1
A starting resistor Rs1 for flowing the current of
You. Similarly, for the base of the switching element Q2,
The base current limiting resistor RB2-the capacitor for resonance CB2
A self-excited oscillation drive circuit comprising a drive winding NB2 connected in series;
Connected. A damper is provided between the base and the emitter.
The diode DD2 is connected, and the
The dynamic resistance Rs2 is connected. Here, the self-excitation of the switching element Q1 is performed.
Of the resonance capacitor CB1 forming the vibration drive circuit
Series depending on the inductance of the drive winding NB1 and the
A resonance circuit is formed. Similarly, the switching element
Resonant capacitor forming self-excited oscillation drive circuit on Q2 side
CB2 capacitance and drive winding NB2 inductance
Also forms a series resonance circuit. And these
Switch determined by resonance frequency of series resonance circuit
Switching elements Q1 and Q2 self-excited depending on switching frequency
The switching drive is performed according to the equation. Also described later.
As described above, in the drive transformer PRT, the drive winding
An alternating voltage in which the lines NB1 and NB2 have opposite polarities is excited.
The switching elements Q1,
Q2 is switched on / off alternately,
Perform the operation. The collector of the switching element Q2
A partial resonance capacitor Cp is connected in parallel between the emitters.
Is connected. The capacitor of this partial resonance capacitor Cp
Leakage inductance of the primary winding N1
Depending on the component L1, a parallel resonance circuit (partial voltage resonance circuit)
To form And the switching elements Q1 and Q2
Voltage resonance only when the power is turned off.
It is supposed to be. [0008] Drive transformer PRT (Power Regulati
ng Transformer) switches the switching elements Q1 and Q2.
Switching for constant voltage control.
It is provided for variably controlling the switching frequency. And this
Of the drive transformer PRT includes drive windings NB1, NB2 and
While winding the resonance current detection winding NA,
The control winding Nc is wound in a direction orthogonal to each winding of
Saturable reactor. The driving winding N
B1 and the drive winding NB2 are excited with voltages of opposite polarities.
It has become so. Insulated converter transformer PIT (Power Is
olation Transformer) is the switching element Q1, Q2
The switching output is transmitted to the secondary side. This insulation transformer
One end of the primary winding N1 of the SPIT is connected to the resonance current detecting winding N
Via A, the emitter of the switching element Q1 and the switch
Contact with the collector of the switching element Q2 (switching output
Switching output is obtained by connecting
Is to be. In this case, the other end of the primary winding N1
Is connected to the primary side ground via the series resonance capacitor C1
Have been. Then, the key of the series resonance capacitor C1 is
Insulation converter with capacitance and primary winding N1
Due to the inductance component of the lance PIT, the primary switch
To make the operation of the switching converter a current resonance type.
A secondary side series resonance circuit is formed. In this way,
The primary side switching converter shown in Fig.
The operation as a current resonance type and the partial voltage resonance operation described above
Are obtained in a complex manner. In this specification,
A switch that can obtain a complex resonance operation as in
Converter is also referred to as a “composite resonance converter”.
I will say. [0011] In this case, the insulation converter transformer
On the secondary side of the PIT, a secondary winding N2 and this secondary winding N2
The secondary winding N3 with fewer turns (turns) than the winding
Have been. For the secondary winding N2, as shown
And the bridge rectifier circuit DBR and the smoothing capacitor CO1
The smoothing capacitor is connected by full-wave rectification
A secondary DC output voltage EO1 can be obtained at both ends of the capacitor CO1.
It has become. The secondary winding N3 is a center tap.
Rectifier diode DO as shown in the figure.
3, DO4 and smoothing capacitor CO2
Thus, a full-wave rectifier circuit is formed, and both the smoothing capacitor CO2
The secondary side DC output voltage EO2 is generated at the end.
These secondary side DC output voltages EO1 and EO2 are shown
Not supplied for loads. Also, the secondary side DC output
The voltage EO1 is also branched as a detection voltage for the control circuit 1.
Is entered. The insulation converter transformer PIT is, for example,
It has the structure shown in FIG. Insulation converter transformer
PIT is E type core CR1, CR2 made of ferrite material
EE type core in which the magnetic legs are opposed to each other
Is provided. Then, the winding areas on the primary and secondary sides are
Independently divided and integrated buttons
For the bin B, the primary winding N1 and the secondary winding N2
It is wound around these winding regions. The primary winding
N1 and the secondary winding N2 are each a litz wire of 60 μmmφ.
Is wound by a gala winding. Also, in FIG.
Has a secondary winding N3 wound on the secondary side, where
Are not shown. And for the center magnetic leg
The gap G is formed as shown in FIG. to this
Therefore, as the coupling coefficient k, for example, k ≒ 0.8
To obtain a loosely coupled state. In addition,
G has two central magnetic legs of E-shaped cores CR1 and CR2.
It can be formed by making it shorter than the outer magnetic leg. In the control circuit 1, the secondary side DC output voltage EO1
Control current flowing through the control winding NC according to the level change of
By changing the (DC current) level, the orthogonal control
Of the drive winding NB wound around the PRT
LB is variably controlled. Thereby, the inductance of the drive winding NB is
Main switching element formed including the conductance LB
Series resonance circuit in the self-excited oscillation drive circuit for the
The resonance condition of the road changes. This is the main switching
The operation changes the switching frequency of the element Q1,
This operation stabilizes the DC output voltage on the secondary side. Further, based on the invention proposed earlier by the present applicant,
Other switching power supply circuits
An example is shown in the circuit diagram of FIG. The power supply circuit shown in FIG.
For the separately excited current resonance type converter,
As a complex resonance type converter combined with a vibration circuit
It has a configuration. In this figure, the same parts as in FIG.
Minutes are assigned the same reference numerals, and common
The description is omitted. In the power supply circuit shown in FIG.
For a commercial AC power supply AC, a bridge rectifier circuit Di and
Equipped with full-wave rectifier circuit consisting of one smoothing capacitor Ci
Can be Therefore, in this case, by the full-wave rectification operation,
A rectified smoothed voltage Ei (DC input) is applied to both ends of the smoothing capacitor Ci.
Force voltage). This rectified smoothed voltage Ei
Is a level corresponding to an equal multiple of the AC input voltage VAC. In this case, the DC input voltage is input to switch
As shown in the figure,
Thus, two switches by the MOS-FET
Devices Q1 and Q2 are connected by half-bridge coupling.
You. Between each source and drain of switching elements Q1 and Q2
To the clamp
The diodes DD1 and DD2 are connected in parallel. Also, Sui
There is a part between the source and the drain of the switching element Q2.
By connecting the resonance capacitor Cp in parallel,
Parallel resonance with the primary winding N1 of the inverter transformer PIT
A circuit (partial voltage resonance circuit) is formed. This
Therefore, the power supply circuit shown in FIG.
Operation as a complex resonant converter.
Is obtained. In this separately-excited power supply circuit,
For switching driving of the switching elements Q1 and Q2
Is provided with an oscillation drive circuit 2 using, for example, a general-purpose IC.
Can be The oscillation drive circuit 2 includes a switching element
A gate as a drive signal for each gate of Q1 and Q2
Voltage. Thereby, the switching element Q
1, Q2 turns on alternately according to required switching frequency
Switch off / off.
It is. The oscillation drive circuit 2 includes an insulating converter.
Low pressure additionally wound on the primary side of the data transformer PIT
A rectifier circuit consisting of winding N4 and capacitor C4
The supplied low-voltage DC voltage is input to be used as an operation power supply. Ma
In addition, at the time of startup, rectification and smoothing are performed via the startup resistor Rs.
It is activated by inputting the voltage Ei. The insulated converter of the power supply circuit shown in FIG.
The lance PIT has a structure similar to that described with reference to FIG.
You. That is, for example, the center magnetic leg of the EE type core is
By forming a gap, the coupling coefficient k between the primary side and the secondary side
Thus, a loosely coupled state of about k = 0.8 can be obtained.
It is what you are doing. The control circuit 1 in this case has a secondary DC output.
Generates a variable DC current according to the level change of the voltage EO1
Supplied to the oscillation drive circuit 2 via the photocoupler PC.
Pay. In the oscillation drive circuit 2, the photocoupler PC is
Switch according to the output of the control circuit 1
The switching frequency of the switching elements Q1 and Q2
Thus, switching driving is performed. Switch in this way
The switching frequency of the switching elements Q1 and Q2 is varied
This stabilizes the level of the secondary DC output voltage.
And FIG. 10 is a circuit diagram of the power supply circuit shown in FIG.
FIG. 6 is a waveform diagram showing the operation of the main part by the switching cycle.
You. The switching operation of the switching element Q2
The collector-emitter voltage VQ2 of the switching element Q2 and
It is indicated by the collector current IQ2. That is, switchon
During the period TOFF when the switching element Q2 is turned off, the collector
The current IQ2 becomes 0 level and the collector-emitter
The inter-voltage VQ2 is clamped by the rectified smoothed voltage Ei.
Level will be obtained. In contrast,
In the period TON during which the switching element Q2 is turned on,
The collector current IQ2 flows according to the waveform shown in FIG.
Collector-emitter voltage VQ2 goes to 0 level. this
The collector current IQ2 is applied to the primary winding N1 during the period TON.
The flowing primary winding current I1 flows. In addition, this
Although not shown here, the switching element Q1 is
ON / OFF at alternate timing with the switching element Q2
Operation of the switching element Q1,
The collector-emitter voltage and collector current are
The collector-emitter voltage VQ2 of the
The waveform of the current IQ2
is there. Therefore, the switching element Q1 is turned on.
The waveform portion of the primary winding current I1 during the period TOFF
The current flowing as the collector current of the switching element Q1
Become. The collector of the switching element Q2
Partial resonance capacitor connected in parallel between emitters
As shown, the switching element Q
At the time of turn-off of 2, a partial resonance current IC2 of positive polarity flows,
When switching element Q1 is turned off (switching element
When the element Q2 is turned on), the partial resonance current IC2 of the negative polarity
So that partial voltage resonance operation is obtained.
You can see that there is. And from such an operation waveform
As can be seen, the switching elements Q1, Q2 are ZVS (Z
ero Voltage Switching) and ZC
S (Zero Current Switching) operation
Operation, and the switching loss can be reduced.
It is planned. A block connected to the secondary winding N2
Between the positive and negative input terminals of the ridge rectifier circuit DBR.
The rectified voltage V2 between the bridge rectifier circuit as shown
Diodes of each positive / negative rectified current path of DBR conduct
, The absolute value level of the secondary side DC output voltage EO1
A level-clamped waveform is obtained. Here,
A detailed description of the power supply circuit shown in FIG.
However, almost the same operation waveform can be obtained. The power supply circuit having the configuration shown in FIG.
As characteristics, AC input voltage VAC = 100V, load power P
AC → DC power change for a change of o = 0 W to 200 W
Conversion efficiency (ηAC → DC), switching frequency fs, and
And ON period TON of the switching element Q2 (or Q1)
11 is shown. As shown in FIG. 11, the load power Po
As the weight increases and the secondary DC output voltage decreases,
The switching frequency fs is controlled to decrease.
It can be seen that the period TON increases accordingly. Ma
Also, the AC → DC power conversion efficiency (ηAC → DC) is, for example,
If the load power Po = 200W, 91.8%, the load power
When Po = 150W, the load power becomes 92.4%.
The most efficient state is obtained at o = 150W
You. The power supply circuit shown in FIG.
10 and the characteristics shown in FIG.
Each part is selected as follows. Primary winding N1 = Secondary winding N2 = 45T Primary-side series resonance capacitor C1 = 0.056 μF Partial resonance capacitor Cp = 330 pF By the way, the power supply circuit and
Therefore, the power conversion efficiency should be as high as possible.
No. However, in the power supply circuits shown in FIGS. 7 and 8,
The resonance frequency fo1 of the primary side series resonance circuit is about 50 KHz
Degrees. And, the minimum input of AC input voltage VAC = 90V
Force voltage and maximum load power Po = 200W
However, for the switching frequency fs, the resonance frequency fo
Fs = 53KHz higher than 1 is maintained.
Therefore, it is stabilized at the secondary side DC output voltage EO1 = 135V
I have to do it. If this condition is not met,
Starting by stable operation of ZVS and ZCS
Is not possible. Therefore, the primary side series resonance
For capacitor C1, select 0.056μF.
For the insulation converter transformer PIT, 1 mm
A gap of about 2 mm is formed and a coupling coefficient k = 0.8
A degree of loose coupling must be obtained. As described above, the primary winding and the secondary winding
Since the line and the line are in a loosely coupled state, AC →
There is a limit to improvement in DC power conversion efficiency (ηAC → DC).
Specifically, load power Po = 125 W, AC input voltage V
AC → DC power conversion efficiency at AC = 100V (ηAC → DC)
Has been described with reference to FIG. 11 in the circuit shown in FIG.
Thus, the limit is about 92%. Also, the circuit shown in FIG.
Road is limited to about 90% when load power Po is about 120W
Especially when the load power Po is higher than 120W.
In this case, it is reduced to about 90%. In addition, the isolation converter transformer PIT is
Being in a coupled state, the isolated converter transformer
The generation level of magnetic flux leakage from SPIT has increased.
U. Therefore, in practice, the isolated converter
By installing a copper plate short ring on the lance PIT
It is necessary to take countermeasures.
To increase the cost and size of transformer PIT
Become. Furthermore, the isolation converter transformer PIT is loosely coupled.
, The primary winding near the gap G and the secondary winding
Side windings are used to reduce eddy current loss due to so-called fringe magnetic flux.
Therefore, the rise in temperature is disadvantageous in terms of reliability.
You. Further, the insulation converter transformer PIT
In forming the gap G in the center magnetic leg,
Like polishing the center leg of ferrite E-shaped core
Is done. In this case, the insulation converter transformer PIT is manufactured.
Polishing process will be added to manufacture
Therefore, there is also a problem that the cost increases
Occurs. Means for Solving the Problems [0030] The present invention has been described above.
Considering the issues, a switching power supply circuit as follows
It was decided to constitute. In other words, the input DC input power
Current that performs switching operation by interrupting the voltage
A switching means having a waveform, and a switch of the switching means.
For transmitting the switching output from the primary side to the secondary side.
A U-U character having no gap formed in the magnetic leg.
Requires at least primary and secondary windings for mold core
The primary winding and the secondary winding
Make sure that tight coupling is achieved with a coupling coefficient greater than required.
An isolated converter transformer configured with at least
Leakage inductance of primary winding of isolated converter transformer
Component and the primary-side series resonance coil connected in series with the primary winding.
Formed by the capacitance of the capacitor
The primary side series resonance circuit that makes the operation of the
Road. Also, a plurality of switching means are formed.
Out of the switching elements
Of the partial resonance capacitor connected in parallel to the
And the leakage of the primary winding of the above isolated converter transformer.
The switch formed by the leakage inductance component
Of the plurality of switching elements forming the switching means
Primary side partial voltage resonance circuit that performs voltage resonance operation during
Prepare. In addition, leakage of the secondary winding of the insulation converter transformer
In parallel with the leakage inductance component and this secondary winding
Capacitor of connected secondary side partial voltage resonance capacitor
And a secondary partial voltage resonance circuit formed by the
I can. And the secondary winding of the isolated converter transformer
Rectifying operation by inputting the alternating voltage
DC output voltage generator configured to generate a current output voltage
Switch according to the level of the secondary side DC output voltage.
By changing the switching frequency of the switching means,
It is configured to perform constant voltage control on the secondary side DC output voltage.
And the established constant voltage control means. According to the above arrangements, the composite resonance type converter
The primary side is a current resonance type switching converter
(Switching means) and primary side partial voltage resonance circuit
The combined configuration is adopted, and then the secondary
Is provided with a secondary side partial voltage resonance circuit. Current resonance type
By adopting the above configuration as a converter, secondary
Power can be covered by the side resonance circuit
As an isolated converter transformer, the primary winding and secondary
The windings are tightly coupled. And this
A combination as a complex resonant converter
Both are isolated converter transformers that are tightly coupled as described above.
Combined with the structure of the
It is possible to increase efficiency. FIG. 1 shows an embodiment of the present invention.
2 shows a configuration example of all switching power supply circuits. this
The power supply circuit shown in the figure
A self-excited current resonant converter
You. In the power supply circuit shown in FIG.
Two slow recovery type rectifier diodes D for C
1, D2 and two smoothing capacitors Ci1, Ci2
It is. The anode of the rectifier diode D1 is a commercial AC power supply
Connected to AC positive line, cathode is smooth condenser
It is connected to the positive terminal of the capacitor Ci1. Smoothing capacitor Ci
1, Ci2 are connected in series. In other words,
The negative terminal of the sensor Ci1 is the positive terminal of the smoothing capacitor Ci2.
And the negative terminal of the smoothing capacitor Ci2 is on the primary side.
Connected to earth. In addition, the rectifier diode D2
The cathode is connected to the primary side ground, and the cathode is
Connected to the positive terminal of power supply AC. Thus, the rectifier diodes D1, D2 and
And smoothing capacitors Ci1 and Ci2 are connected,
Rectified smoothed voltage Ei (DC input voltage) from AC power supply AC
The rectifier circuit system that generates
Is done. Thereby, the smoothing capacitor C connected in series
Both ends of i1-Ci2 have a level twice as high as the AC input voltage VAC.
Thus, a rectified smoothed voltage Ei corresponding to the current value is obtained. The primary self-excited current shown in FIG.
As shown in the figure, two switches
It is provided with the switching elements Q1 and Q2. In this case, switching
A bipolar transistor is selected for the elements Q1 and Q2.
Is defined. These switching elements Q1, Q2 are
Are connected by a self-bridge connection method. Toes
And the collector of the switching element Q1 is a rectified smooth voltage.
Contact with Ei line (positive terminal of smoothing capacitor Ci1)
Continued. The emitter of the switching element Q1 is
Connected to the collector of the switching element Q2,
The emitter of the child Q2 is connected to the primary side ground. The base of the switching element Q1 is
As a result, the base current limiting resistor RB1-the resonance capacitor C
Self-excited oscillation drive circuit consisting of B1-drive winding NB1 connected in series
Is connected. Here, the resonance capacitor CB1-drive winding
The series connection of the line NB1 depends on the capacity of the resonance capacitor CB1.
Series with the inductance of the drive winding NB1
A resonance circuit is formed, and the resonance frequency of this series resonance circuit
The number determines the switching frequency. Also,
Source current limiting resistor RB1 is switched from the self-excited oscillation drive circuit.
The drive signal to be passed to the base of the
Adjust the source current level. The base-E of the switching element Q1
In the direction shown in the figure, the damper diode DD1 is between the transmitters.
Connected in the reverse direction during the on-period.
Form a flow path. Also, the switching element Q1
To allow the current at startup to flow between base and base
Is connected. Similarly, the base of the switching element Q2
The base current limiting resistor RB2-capacitor for resonance
Self-oscillation drive comprising a series connection of a sensor CB2-drive winding NB2.
The driving circuit is connected. Then, the resonance capacitor CB2-
The drive winding NB2 forms a series resonance circuit. Ma
A damper diode DD2 is provided between the base and the emitter.
Is connected, and a starting resistor Rs2 is provided between the collector and the base.
Connected. The collector of the switching element Q2
A partial resonance capacitor Cp is connected in parallel between the emitters.
Is connected. The capacitor of this partial resonance capacitor Cp
Leakage inductance of the primary winding N1
Depending on the component L1, a parallel resonance circuit (partial voltage resonance circuit)
To form And the switching elements Q1 and Q2
Voltage resonance only when the power is turned off.
It is supposed to be. Drive transformer PRT (Power Regulati
ng Transformer) switches the switching elements Q1 and Q2.
Switching for constant voltage control.
It is provided for variably controlling the switching frequency. This dry
The transformer BRT includes the drive windings NB1, NB2 and the resonance current.
The detection winding NA is wound, and each of these windings is further wound.
The control winding Nc is wound in a direction orthogonal to
It is a Japanese reactor. The drive winding NB1 and the drive
The dynamic winding NB2 has a winding direction in which voltages of opposite polarities are excited.
It is wound by. Insulated converter transformer PIT (Power Is
olation Transformer) is the switching element Q1, Q2
The switching output is transmitted to the secondary side. This insulation transformer
One end of the primary winding N1 of the SPIT is connected to the resonance current detecting winding N
The emitter and the switching element of the switching element Q1 via A
To the collector contact of the switching element Q2 (switching output point)
By connecting, so that switching output can be obtained
Is done. As shown in the figure, the other end of the primary winding N1
Is connected to the primary side ground via the series resonance capacitor C1
Have been. Then, the key of the series resonance capacitor C1 is
Insulation converter with capacitance and primary winding N1
Due to the inductance component of the lance PIT, the primary switch
To make the operation of the switching converter a current resonance type.
A secondary side series resonance circuit is formed. Also, the present embodiment
, The resonance frequency fo of the primary side series resonance circuit
1 is set to 90 KHz or less. This
Therefore, for the primary-side series resonance capacitor C1,
0.1 μF. Thus, shown in this figure
As the primary side switching converter, the current resonance type
Operation and the partial voltage resonance operation described above
It has been obtained. In this specification,
Switching converter that can provide complex resonance operation
Data converter is also called a “composite resonance converter”
I do. As a switching operation of the power supply circuit,
Is, for example, as follows. First, commercial AC power supply AC
When the switch is turned on, for example, the switch
The base power for starting is connected to the bases of the switching elements Q1 and Q2.
Flow will be provided. Where, for example,
The drive windings NB1 and NB2 of the lance PRT have opposite polarities.
Voltage will be excited, so the switching element
If Q1 is turned on first, the switching element Q2
Is controlled to be off. And these drive windings
The switch is driven by the alternating voltage excited on the lines NB1 and NB2.
The self-excited oscillation drive circuits of the tuning elements Q1 and Q2
Performs self-oscillation operation. This allows switching
The elements Q1 and Q2 are controlled to be turned on / off alternately.
You. That is, a switching operation is performed. And
For example, when the switching element Q1 is turned on,
As the switching output, a resonance current detection winding NA is used.
The primary winding N1 and the series resonance capacitor C1
When the resonance current becomes zero, the
Switching element Q1 is turned off and the switching element
The child Q2 is turned on. Thereby, the switching element Q2
, A resonance current flows in the opposite direction to the previous one. Hereafter, ZV
Switching elements Q1 and Q2 alternate by S and ZCS
The self-excited switching operation which is turned on is continued.
In addition, the switching elements Q1 and Q2 are turned on / off.
Short period when the switching elements Q1 and Q2 are turned off
, A current flows through the partial resonance capacitor Cp.
That is, a partial voltage resonance operation is obtained. Also, the insulation converter transformer PIT
For the secondary winding N2, a secondary partial voltage resonance capacitor
C2 are connected in parallel. For example, this secondary partial voltage
A film capacitor is used as the resonance capacitor C2.
Used. And this secondary side partial voltage resonance capacitor
The capacitance of C2 and the leakage of secondary winding N2
Depending on the inductance L2, the secondary side partial voltage resonance circuit
Is formed. Therefore, the insulation converter transformer PI
When the alternating voltage is excited in the secondary winding N2 of T,
Must be able to achieve partial resonance (voltage resonance) operation on the secondary side.
And That is, the power supply circuit shown in FIG.
As a converter, the primary side performs current resonance operation and partial
Pressure resonance operation and partial voltage on the secondary side.
Pressure resonance operation.
You. The secondary winding N2 is shown in FIG.
Thus, the bridge rectifier circuit DBR and the smoothing capacitor CO1
Are connected to form a full-wave rectifier circuit. this
The full-wave rectification circuit operates the smoothing capacitor
So that the secondary side DC output voltage EO1 can be obtained at both ends of CO1
Has become. This secondary side DC output voltage EO1 is not shown.
Is supplied to the load. Furthermore, this secondary side DC output
Force voltage EO1 is detected for control circuit 1 as shown.
The voltage is also branched and input. Here, the power supply circuit shown in FIG.
As an example of an isolated converter transformer PIT,
The structure shown in FIG. First, this isolated converter
In the trans PIT, as its core, for example, FIG.
U-shaped core CR having two magnetic legs as shown in FIG.
11 and a U-shaped core CR12. These U type
The core CR11 and the U-shaped core CR12 are respectively
The back shape of the main body with respect to the magnetic legs is such that one side has a predetermined length a.
It has a square shape. And these U
The cores CR11 and CR12 are
As shown in FIG.
Are combined to form a U-U core. Further
Then, one of the U-U type cores formed as described above
For the magnetic leg, the primary winding N1 and the secondary winding
A winding in which the next winding N2 is wound around a winding area divided from each other.
Bin B is attached. In the present embodiment, the structure formed as described above is used.
No gap is formed with respect to the central magnetic leg of the UU type core.
I am trying. And in this way to U-U type core
After the gap is not formed, for example,
Winding width of winding N1 and secondary winding N2
Is tightly wound, so that the coupling coefficient k is about 0.99.
It is designed to obtain the degree of bonding that is to be bonded. Here, for example, in the power supply circuit of the prior art,
Insulated converter transformer PIT with loose coupling
In this way, abnormal oscillation during intermediate load is suppressed.
Was. On the other hand, in the power supply circuit of this embodiment, the secondary
By the resonance operation of the partial voltage resonance circuit provided on the side,
Abnormal oscillation is prevented from occurring at the time of intermediate load. Toes
In this way, the isolated converter transformer
Even if the PIT is configured to be in a tightly coupled state,
No problems will occur in the operation of the road. In FIG. 1, the control circuit 1 has a secondary DC output.
Control flow to the control winding NC according to the level change of the force voltage EO1
By varying the control current (DC current) level,
Inductance of drive winding NB wound on control transformer PRT
LB is variably controlled. Thereby, the drive winding NB
Main switch formed including inductance LB
Resonance circuit in the self-excited oscillation drive circuit for the switching element Q1.
The resonance condition of the road changes. This is the main switching
The operation changes the switching frequency of the element Q1,
This operation stabilizes the DC output voltage on the secondary side. The main component elements in the above configuration are
The following selection was made. Primary winding N1 = 54T Secondary winding N2 = 60T Primary side series resonance capacitor C1 = 0.1μF Partial resonance capacitor Cp = 680pF Secondary side partial voltage resonance capacitor C2 = 1500pF And each element is selected in this way. By having
The resonance frequency fo1 of the primary side series resonance circuit is 90 KHz
It is set to be as follows. The waveform diagram of FIG. 5 is similar to the configuration shown in FIG.
The operation of the main part of the power supply circuit is shown. What
The operation shown in this figure is based on the AC input voltage VAC = 100 V
Measurement results under the condition of load power Po = 200W
The result is shown. The switching element Q2 is in the period TON
On during the period TOFF
Perform the switching operation. And the switching element
The switching current IQ2 flowing through Q2 is
Then, during the period TOFF, the level is 0, and during the period TON,
First, at the start, the damper diode DD2
From the base of the switching element Q2 to the collector
Damper current flows in the positive direction of the negative electrode.
It has a waveform flowing through the emitter. The collector of the switching element Q2
The emitter-to-emitter voltage VQ2 is rectified and smoothed during the period TOFF.
The voltage clamped at the level of the voltage Ei (DC input voltage)
Waveform during the period TON
Is obtained. The switching element Q1 is a switch
To turn on / off the switching element Q2 alternately
Switching. Therefore, the switching element Q
1 switching current and collector-emitter voltage
Therefore, the switching current IQ2 and the collector-emitter
It has the same waveform shape as the
The phase is shifted by 80 °. In this figure, the primary winding N1
The primary winding current I1 flowing as the switching output is shown.
Have been. This primary winding current I1 is
Primary side series resonance according to switching operation of Q1 and Q2
Obtained by the resonance operation of the series resonance circuit of the circuit (C1-N1)
The resonance current. The primary winding current I1
Means that switching element Q1 is off and switching element Q2
During the period TON during which the switching element is turned on, the switching element Q
2 as switching current IQ2 to switching element Q2
It will flow. Switching element Q2 is off.
In the period TOFF during which the switching element Q12 is turned on
The switching current of the switching element Q1
It will flow to the switching element Q1. Further, the collector of the switching element Q2
Partial resonance capacitor connected in parallel between emitters
As shown, the switching element Q
Partial resonance voltage of positive polarity in the short period of turn-off
When current IC2 flows and switching element Q1 is turned off
(When the switching element Q2 is turned on)
So that the negative partial resonance current IC2 flows.
You. Thus, the switching elements Q1 and Q2 turn
When off, partial voltage resonance operation is obtained
I understand. And you can see from such operation waveforms
Thus, the switching elements Q1 and Q2 are connected to ZVS (Zero Volt
age Switching: Zero voltage switching and ZCS (Zero
Current Switching (zero current switching) operation is obtained
You. Further, the insulation converter transformer PIT
The operation on the secondary side is based on the secondary winding current I2 flowing through the secondary winding N2.
It is indicated by the voltage V2 across the secondary winding N2. This place
In this case, the primary winding N2 is connected to the secondary winding N2 as shown in the figure.
An alternating current flows with the same polarity as the current I1. Also, two
The voltage V2 across the secondary winding N2 is equal to the positive voltage of the bridge rectifier circuit DBR.
/ Negative rectified current path as the diode conducts
The absolute value level is the level of the secondary side DC output voltage EO1.
The result is a clamped waveform. In this figure, the secondary side having a small capacity is shown.
The resonance current IC3 flowing through the partial voltage resonance capacitor C2 is also shown.
Have been. This resonance current IC3 is calculated by the bridge rectifier circuit D
Fast recovery diode that forms BR turns on,
It flows at the turn-off timing,
The partial voltage resonance operation is obtained on the secondary side. Soshi
Therefore, corresponding to the period during which the resonance current IC3 flows,
High-speed recovery type diode forming a bridge rectifier circuit DBR
Applied voltage (V2) is inverted.
Sometimes, it is shown that the waveform shape has a slope.
Is done. Here, FIG. 1 constructed as described above
The power supply circuit according to the first embodiment shown in FIG.
Let's compare it with the power supply circuit as the prior art. Destination
First, as a circuit configuration, in the circuit shown in FIG.
The resonance frequency fo1 of the resonance circuit is set to about 50 KHz.
Have been. The stabilization of the power supply circuit of the present embodiment is performed on the primary side.
Frequency region higher than resonance frequency fo1 of series resonance circuit
By variably controlling the switching frequency with
Is done. In this case, for example, the switching frequency fs
The lower limit of the variation range is the minimum input of AC input voltage VAC = 90V
Voltage and maximum load power Pomax = 200W
It becomes. And even under this condition, the secondary side DC output voltage
EO1 will be stabilized at the specified 135V, for example.
In order to achieve this, the lower limit switching frequency fs
About, for example, 53KHz higher than 50KHz
It needs to be. For this reason, primary side series resonance
0.056 for the capacitance of capacitor C1
μF is selected. After that, ZVS and ZCS
It is necessary to obtain a stable startup operation
However, for this reason, the isolation converter transformer PIT
To form a loose coupling with a coupling coefficient k = about 0.8.
It was in the state. On the other hand, the present embodiment shown in FIG.
In the power supply circuit of FIG.
Regarding the pacitance, for example, by setting it to 0.1 μF,
The resonance frequency fo1 of the primary side series resonance circuit is 90 kHz or less
So that it is below. Then, the secondary winding N2
Connect the secondary side partial voltage resonance capacitor C2 in parallel
So that a partial voltage resonance can be obtained on the secondary side.
are doing. In other words, the current resonance converter on the primary side
In addition to the current resonance operation and partial voltage resonance operation of
Complex resonant converter combining partial voltage resonant operation
The configuration is as follows. And such a configuration
By doing so, the coupling coefficient of the isolated converter transformer PIT is
Start with stable ZVS and ZCS even when set high
Becomes possible. Therefore, the insulation converter according to the present embodiment
As described above, the primary winding N
1 and the winding width of the secondary winding N2
Is not formed, and the density of the coupling coefficient k is about 0.99.
It was decided to increase the degree of bonding before the bonding. like this
In the isolated converter transformer PIT, the primary
By making the side and the secondary side tightly coupled,
As a result, transmission efficiency from the primary side to the secondary side is improved,
Therefore, the power conversion efficiency is improved. Also, as described above, the insulated converter
If there is no gap in the lance PIT
No need to create gaps in manufacturing
Therefore, the manufacturing process is simplified and the cost is reduced.
Can be planned. In addition, close coupling
And the leakage flux from the insulated converter transformer PIT
As a result, for example, a short ring made of copper
There is no need to wind around the edge converter transformer PIT
Become. In this regard, the insulation converter transformer PIT
The manufacturing process is simplified, and cost reduction is promoted.
Will be. In addition, the elimination of the gap
Local temperature rise of windings of edge converter transformer PIT
Problem is solved, and the reliability is improved
Become. Further, in the present embodiment, the insulating capacitor
The U-transformer shown in FIG.
By using a U-shaped core, for example, in FIG.
As shown, EE used in the power supply circuit of FIG.
Smaller and lighter than the core
You. For example, in the case of the EE type core of FIG.
133mm back area of main body ^Two Weighs 118g
On the other hand, in the case of the UU type core of the present embodiment,
Area is 94mm ^Two , Weight is 80g, area is 70g
% And weight will be reduced to 68%. FIG. 6 shows the present embodiment shown in FIG.
As a characteristic of the power supply circuit, the AC input voltage VAC =
Load power Po = 25 W to 200 W at 100 V
→ DC power conversion characteristics (ηAC →
DC), switching frequency fs, and switching element
The change of the ON period TON of the child Q2 (or Q1) is shown. First,
AC → DC power conversion efficiency (ηAC → DC)
For example, when the maximum load power Pomax = 200 W,
7 is ηAC → DC = 91.
8%, the power supply circuit of FIG.
C = 93.5%, which is an improvement of 1.7%
You. When Po = 50 W, the power supply circuit of FIG.
C → DC = 87.0%, power supply circuit of FIG. 1 is ηAC → DC
= 90.5%, and in this case, an improvement of 3.5%
Will be able to To support this, the power supply circuit shown in FIG.
In FIG. 5, the primary side resonance current I1 shown in the waveform diagram of FIG.
Peak level Plv2 and switching current IQ2 peak
The level P-Plv2 is in the circuit of FIG. 7 shown in FIG.
Peak level Plv1 of primary side resonance current I1, and switch
Of the switching current IQ2 compared to the peak level P-Plv1.
Some experimental results have been obtained. It depends on the experiment
And these peak levels in the case of the power supply circuit of FIG.
7, which is reduced to about 65%. Further, in the power supply circuit shown in FIG.
AC input power is supplied to the power supply circuit shown in FIG.
Road)), a reduction of 4.0 W
4.2W for a power supply circuit (in the case of a full-wave rectifier circuit)
Some experimental results have been obtained indicating that it has been reduced. Thus, the power conversion efficiency is improved.
The reason is that the isolated converter transformer PIT is tightly coupled.
And the secondary side partial voltage resonance capacitor C2
To provide voltage resonance operation on the secondary side.
According to FIG. 6 shows that the switching frequency f
s should decrease as the load increases
It can be seen that it is controlled to The switching element
The period TON, which is the ON period of the child Q2, is the switching frequency.
Controlled to be longer as the number is controlled lower
You can see that it is. And the load power Po = 25W
Variable switching frequency fs in the range of ~ 200W
The range is fs = 83-500KHz
Shown, the actual frequency control range Δfs = 417K
Hz. In contrast, the power supply shown in FIGS.
In the circuit, the load power in the range of Po = 0 W to 200 W is used.
The variable range of the switching frequency fs is fs = 60 to 167.
KHz, frequency control range Δfs = 107 KHz,
As the frequency control range Δfs, the power supply circuit shown in FIG.
Is about four times larger.
That is, in the power supply circuit of FIG.
This is intended to increase the efficiency of wave number control.
Insulated converter transformer PIT is tightly connected as described above
Low leakage inductance
It depends on having decreased. Here, the circuit configuration of the power supply circuit shown in FIG.
FIGS. 2 and 3 show a modification of FIG.
Will be shown below. In the configuration shown in FIG.
Set a center tap for
Connected to secondary ground. In this case,
Is connected in parallel with the secondary winding N2.
The capacitor C2 is connected. Then, the secondary winding
For both ends of N2, two rectifiers are
It consists of diodes DO1, DO2 and a smoothing capacitor CO1.
To form a full-wave rectifier circuit. This full-wave rectification
The secondary side DC output voltage EO1 is obtained by the rectification operation of the circuit.
To be done. In FIG. 3, the secondary side partial voltage resonance
Shown for the secondary winding N2 with the capacitor C2 connected in parallel
Depending on the connection configuration, two rectifier diodes DO11,
Connect DO12 and two smoothing capacitors CO1 and CO2
By forming a voltage doubler rectifier circuit by full-wave rectification,
I have. And the voltage doubler rectification operation by this voltage doubler rectifier circuit
Depending on the operation, rectifier diodes DO11-DO connected in series
At both ends of 12, twice the alternating voltage excited by the secondary winding N2
To obtain the secondary side DC output voltage EO1 of the level corresponding to
To be. The switching power supply circuit according to the present invention
The route is the same as that of each of the embodiments described above.
It is not limited to the configuration, for example, the main component element
Constants are changed to appropriate values according to various conditions.
It should just be. For example, in the present embodiment, the primary side series
When the vibration frequency fo1 is set near 90 KHz
Is given as an example. However, this is only a switch
Upper side control is possible for the switching frequency.
Within a selectable range for the series resonance frequency fo1
It is merely an example of the upper limit.
You. Therefore, within the selectable range, the series resonance frequency
It is possible to appropriately change and set fo1. Ma
For example, used for primary side switching converter
As the switching element, the bipolar element shown in each circuit diagram is used.
In addition to transistor, MOS-FET and IGBT
May be adopted. In addition, MOS-FET and IGB
When T is adopted, it is driven separately.
It is possible that it is. In each embodiment,
In the circuit diagram shown, the DC input voltage (rectified smoothed voltage Ei)
The rectifier circuit system that generates the voltage was a voltage doubler rectifier circuit
Generates a DC input voltage at the same level as commercial AC power.
Full-wave rectifier circuit. And all this
Even with a configuration with a wave rectifier circuit, the power conversion efficiency
The effects of the present invention including the above can be sufficiently obtained.
This is the experimental result obtained. As described above, in the present invention, the composite
As a resonant converter, on the primary side, current resonance
-Type converter combined with partial voltage resonance circuit
And a secondary-side partial voltage resonance circuit for the secondary side.
Make up. And about the isolated converter transformer
U-U-shaped core, primary winding and secondary winding
After winding the wire with the required winding width,
So that the primary and secondary sides are tightly coupled.
It is in a state. And with such a configuration
If there is a significant power conversion compared to the prior art power supply circuit
Efficiency will be improved. In addition, the insulation converter transformer
By eliminating the need for forming a gap,
The step of polishing the core for formation is omitted. This
This simplifies the manufacturing process, for example, and
The cost of manufacturing inverter transformers can also be reduced.
Wear. Further, as described above, the insulated converter transformer
The primary and secondary windings wound around the coil are tightly coupled.
In some cases, the leakage
Since the bundle is reduced, for example, in an isolated converter transformer
There is no need to apply a short ring. And
Also in this regard, cost reduction is achieved, and the circuit is compact.
Lightening is promoted. Also, isolated converter
Local temperature rise near transformer gap
The power supply circuit.
Reliability will be improved. Also, by being tightly coupled,
The leakage flux from the insulated converter transformer is reduced.
Depending on the switching frequency of the power supply circuit,
The control range is expanded, and this allows constant voltage control.
Operation efficiency is improved. Also, as described above, the insulated converter
Use a U-U-shaped core as the transformer.
And it is smaller and lighter than the EE type core used conventionally.
Quantification will be achieved.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a circuit diagram showing a configuration example of a switching power supply circuit according to an embodiment of the present invention. FIG. 2 is a circuit diagram showing a modification of the configuration on the secondary side of the switching power supply circuit according to the embodiment; FIG. 3 is a circuit diagram showing a modification of the configuration on the secondary side of the switching power supply circuit according to the embodiment; FIG. 4 is a diagram illustrating a structural example of an insulating converter transformer provided in the power supply circuit of the embodiment. FIG. 5 is a waveform chart showing an operation of the power supply circuit of the embodiment. FIG. 6 is a diagram illustrating the change characteristics of AC → DC power conversion efficiency, switching frequency, and on-period of a switching element with respect to a load change in the power supply circuit according to the embodiment; FIG. 7 is a circuit diagram showing a configuration example of a switching power supply circuit as a prior art. FIG. 8 is a circuit diagram showing another configuration example of a switching power supply circuit as a prior art. FIG. 9 is a cross-sectional view showing a structural example of an insulating converter transformer used in the power supply circuit shown in FIG. 7 or FIG. FIG. 10 is a waveform chart showing an operation of the power supply circuit shown in FIG. 7 or FIG. FIG. 11 is a diagram showing the change characteristics of the AC → DC power conversion efficiency, the switching frequency, and the ON period of the switching element with respect to a load change in the power supply circuit shown in FIG. 7 or FIG. [Description of Signs] 1 Control circuit, Di, DBR bridge rectifier circuit, D
1, D2 rectifier diode, Ci1, Ci2 smoothing capacitor, Q1, Q2 switching element, PIT isolation converter transformer, N1 primary winding, N2 secondary winding, C1
Primary side series resonance capacitor, Cp Primary side partial resonance capacitor, C2 Secondary side partial voltage resonance capacitor

Claims (1)

Claims: 1. A current resonance type switching means for performing a switching operation by interrupting an input DC input voltage, and transmitting a switching output of the switching means from a primary side to a secondary side. At least a primary winding and a secondary winding are wound with a required winding width on a U-U-shaped core in which no gap is formed in the magnetic leg. An insulating converter transformer configured so that the secondary winding and the secondary winding are in a tightly-coupled state with a coupling coefficient larger than required; at least a leakage inductance component of the primary winding of the insulating converter transformer; A primary-side series resonance circuit formed by the capacitance of a series-connected primary-side series resonance capacitor, wherein the operation of the switching means is a current resonance type. And a plurality of switching elements forming the switching means, formed by the capacitance of a partial resonance capacitor connected in parallel to a predetermined switching element and a leakage inductance component of a primary winding of the insulating converter transformer, A primary-side partial voltage resonance circuit that performs a voltage resonance operation during a turn-off period of the plurality of switching elements forming the switching means; a leakage inductance component of a secondary winding of the insulating converter transformer; A secondary side partial voltage resonance circuit formed by the capacitance of a secondary side partial voltage resonance capacitor connected in parallel, and an alternating voltage obtained in a secondary winding of the insulating converter transformer are input to perform a rectification operation. A DC output configured to generate a secondary DC output voltage Pressure generating means, and a constant voltage control configured to perform constant voltage control on the secondary DC output voltage by varying a switching frequency of the switching means according to the level of the secondary DC output voltage. Means, and a switching power supply circuit comprising: