JP7352327B1 - Resonant current controlled DC power supply - Google Patents

Abstract

The present invention requires at least a resonance switch and an output control switch to configure a resonant DC/DC converter, but the challenge is to further simplify the circuit configuration and improve efficiency. SOLUTION: In a resonant current control type DCDC converter 200, a flyback DCDC converter 230-2 causes a current to flow from a charging voltage of a resonant capacitor Cr to an inductor Ld while a switch S is on, and a current of the inductor Ld is caused by an off signal. continues to flow to the load side, but the next resonant current operation is started by a common current control operation in which the current from the resonant capacitor Cr is turned off. By combining resonance operation and output control operation, it is possible to further simplify the circuit configuration and improve efficiency, and by using the full-wave rectified output of the AC power supply for the DC power supply, the AC current waveform and power factor are also improved. do. [Selection diagram] Figure 7

Description

The present invention aims to improve the power quality of DC power supplies for loads that consume electrical energy in relatively large-capacity application fields, such as power supplies for LED lighting equipment as light sources, and inverter air conditioners with relatively large capacity. This is a technology that contributes to lower prices.

In addition to its inherent characteristics of low power consumption and long life, LED lighting has expectations for energy savings and improved control functions, and has become widely popular as lighting equipment has become cheaper in recent years.

LED lighting power supplies are loads that consume electrical energy unilaterally according to demand requirements, so they can be put to practical use even with extremely simple circuit configurations. It is required to have characteristics required by the circuit configuration.

A typical power supply for LED lighting rectifies the AC power and smoothes it with an electrolytic capacitor, and then controls the dimming with a switch circuit. Products with a PFC (Power Factor Correction) rectifier circuit added as a power factor improvement measure have a high operating voltage as a drive power source for LED lighting, and a DC-DC converter is connected to the subsequent stage to lower the voltage. There were issues such as a two-stage configuration, which made the circuit configuration even more complicated.

On the other hand, in the configuration of a DC power source for an inverter such as an inverter air conditioner, the operating voltage is relatively high and the operating current is large compared to an LED lighting power source, so the current waveform distortion during rectification operation has a large effect on peripheral devices.

For this reason, PFC converters are also used in the DC power supply configuration for inverter air conditioners, which not only complicates the main circuit configuration but also poses issues such as switching loss and high frequency noise, so various improvement measures have been taken. There is.

To address these issues, we have implemented a control system that combines resonant rectification control operation using soft switching technology, which is effective in reducing switching loss and switching noise, and current control operation using a DC/DC converter connected to the resonant rectification control operation, although it has an extremely simple circuit configuration. Based on excellent inflow current characteristics, a resonant AC-DC power supply (Patent Document 7) was invented that can realize output voltage and current control by switching control using two switching elements to solve the problem of DC-DC converters. ing.

This power supply can charge the resonant capacitor with zero current soft switching by turning on the first switching element, and turns on and off the second switching element of the DC-DC converter connected to the resonant capacitor. By controlling the current width, it is possible to control the output voltage and current of the rectifier circuit and improve the inflow current waveform at a constant switching frequency.

Furthermore , the present invention aims to realize charging of a resonant capacitor by a resonant current and control of output voltage and current of a DC-DC converter only by controlling on/off of a second switching element without using a first switching element. As a result , it is possible to further simplify the main circuit configuration and eliminate conduction loss in the switching elements, and further improvement in efficiency can be expected.

Patent application 1990-97272: “Single stone resonant converter” Patent application 1995-213050: “Resonant converter” Patent application 2007-28829: “Resonant current control method” Patent No. 6667750: “DC-DC converter” Patent No. 6775745: “AC-DC converter” Patent No. 7137260: “AC-DC power supply” Patent application 2023-0470731: “Resonant type AC-DC power supply”

Power electronics devices, in principle, have no loss if ideal switching control is achieved, so development is progressing toward faster switching elements, and in recent years SiC semiconductors and GaN have replaced conventional silicon semiconductors. With the availability of semiconductors, this trend is expected to continue rapidly.

By increasing the switching frequency, inductors, capacitors, transformers, etc. can be made smaller, leading to rapid improvements in efficiency and miniaturization and weight reduction of devices.

On the other hand, with hard switching control, even if the switching characteristics can be made faster, the problem of switching loss and switching noise that accompanies switching remains.

On the other hand, if switching control can be performed when the voltage or current applied to the switching element is zero, these problems can be solved and it is put into practical use as soft switching control, but the circuit configuration and control system for performing soft switching control are The problem is that the technology is becoming more complex.

(Patent Document 1) attempts to solve the problem of resetting the magnetic flux of a transformer by causing resonance operation on the secondary side of the transformer of a flyback DC/DC converter, and the configuration can be controlled with a single switch. Although the circuit configuration is simple, it requires control of the switching frequency, which poses a challenge.

(Patent Document 2) is a DC/DC converter method that controls the switching timing between two switching elements used for LC resonance control and output control, and has the feature that the switching frequency for resonance operation can be kept constant. There are issues such as the complexity of timing control.

(Patent Document 3) uses an LC resonant circuit and two switching elements, and is similar to (Patent Document 2), but is characterized in that the magnitude of the resonant current can be changed according to the weight and weight of the load. It is said that

(Patent Document 4) is an isolated DC-DC converter using soft switching control using a high-frequency square wave voltage source inverter, and since the resonant current changes according to the load current, it is possible to reduce the load when the load is low, similar to (Patent Document 3). The current flow loss due to the resonance current can be suppressed, but the main circuit configuration becomes complicated.

The above is a control method when the resonance control technology is applied to a DC-DC converter, but in the case of an AC-DC converter that obtains a DC power source from an AC power source, it is required to improve the inflow current characteristics of the rectifier circuit.

(Patent Document 5) applies the resonant circuit operation of (Patent Document 4) that takes advantage of the fact that the resonant current changes depending on the load current to an AC-DC converter, and the amplitude of the resonant current changes depending on the AC power supply voltage. Since it is proportional, the inflow current waveform can be made into a sine wave by simply connecting a high frequency filter.

However, in the case of an LED having a constant forward voltage drop as a DC load or a smoothing capacitor connected to the DC output, a sinusoidal waveform is not obtained.

(Patent Document 6), in order to overcome this problem, inserts a step-up DC/DC converter between the resonant capacitor and the smoothing capacitor, and uses switching control to control the inflow current waveform even when a load such as an LED is connected. This allows the waveform to be improved to almost a sine wave.

However, in (Patent Document 6), in order to control the output voltage , it is necessary to change the switching operating frequency, and in particular, significant voltage and current control becomes a problem.

(Patent Document 7), in order to overcome this problem, inserts a buck-boost DC/DC converter between a resonant capacitor and a DC load, and after the resonant current that charges the resonant capacitor becomes zero, the buck-boost DC/DC converter is By controlling the conduction width of the switch, it is possible to control the DC output voltage and current with a nearly sinusoidal inflow current at a constant switching frequency.

Further , (Patent Document 7) uses a flyback converter as a DC/DC converter, thereby making it possible to obtain an arbitrary output voltage isolated by the transformation ratio of the transformer.

Furthermore, by configuring the two switches as a charge pump, the drive circuit can be simplified.

The present invention aims to further simplify and improve the efficiency of the resonant AC-DC power supply described in Patent Document 7, which has such excellent characteristics.

(Patent Document 7) discloses a first switch circuit having a reverse current prevention function for causing a resonant operation of an LC resonant circuit, and a voltage charged in a resonant capacitor with a resonant current to a DC load via a DCDC converter. Since the configuration is controlled by a second switch circuit for supplying power and controlling the DC output voltage and current, the main circuit configuration and the drive circuits for the two switches are somewhat complicated.

Further, since the first switch is soft-switched and controlled with zero current by the resonant current, the switching loss can be suppressed to a low level, but the conduction loss proportional to the magnitude of the resonant current leads to a decrease in efficiency.

The present invention overcomes these problems by configuring only the second switch without using the first switch, and in addition to the excellent features of (Patent Document 7), Since it can be configured without any elements, the main circuit configuration and control system can be simplified, and unnecessary switching control noise caused by the first switching element and conduction loss can be eliminated, making it possible to further reduce noise and improve efficiency. It is possible to realize a resonant current controlled DC power supply.

FIG. 1 shows a resonant current-controlled DC-DC converter circuit configured with an LC resonant circuit section and a buck-boost DC-DC converter section of a resonant AC-DC power supply disclosed in Patent Document 7.

With respect to the DC power source Es, the voltage of the resonant capacitor Cr charged by the resonant current of the LC resonant circuit controlled by the first switch circuit having a reverse current prevention function is passed through the second switch of the buck-boost type DC-DC converter. By controlling the width Ton, the DC output voltage and current can be controlled.

Figure 2 shows the resonant current ir for the switching signals of the first switch and the second switch, the resonant voltage er of the resonant capacitor, the current id1 flowing from the resonant capacitor Cr to the second switch, and the load when the second switch is off. It shows the waveform of the current id2 flowing through the circuit.

Here, a resonance current ir proportional to the difference voltage ΔE between the DC power supply voltage Es and the charging voltage of the resonance capacitor Cr at the time when the first switch S1 is turned on flows.

For this reason, when the load current is small, the voltage drop across the resonant capacitor Cr is reduced, so the differential voltage ΔE is small and the resonant current ir is also small. However, when the load current is large, the voltage drop across the resonant capacitor Cr increases, reaching zero voltage. , and the resonant current ir becomes maximum.

FIG. 3 is a circuit diagram of a one-switch resonant current control type DC-DC converter in which the first switch S1 is turned on and the second switch is synchronized with the resonance period of the LC resonant circuit to control the current flow width.

FIG. 4 shows the switching operation waveforms of each part in this DCDC converter circuit when the first switch S1 is in the ON state and the conduction width of the second switch S2 is controlled.

In the figure, by turning on the second switch S2, the voltage of the resonant capacitor Cr decreases, and the difference voltage ΔE between the DC power supply voltage Es and the voltage er of the resonant capacitor Cr when the second switch S2 is turned off after the conduction width Ton. This shows that a resonant current ir proportional to .

Although the timing at which the resonant current starts to flow in the LC resonant circuit is different, it can be seen that the resonant current ir flows in proportion to the differential voltage ΔE caused by the magnitude of the load current due to the current width control of the second switch S2.

In other words, even if the resonant current control is not performed by the first switch S1, the resonant current control and the output voltage/current control can be performed only by the second switch S2 without using the first switch. Compared to the case where a switch is used, not only can the main circuit configuration be simplified, but also switching loss and switching noise due to conduction loss and soft switching operation in the first switch S1 can be eliminated.

Figure 5 shows a flyback converter that uses a transformer in place of the DCDC converter in Figure 3. By using a transformer, the voltage control range is not limited by setting the transformation ratio, and it is isolated from the DC power supply. DC output can be obtained.

Next, FIG. 6 shows a resonant current control type step-down DC-DC converter circuit in which the buck-boost type DC-DC converter circuit of FIG. 3 is replaced with a step-down type DC-DC converter circuit.

FIG. 7 shows a resonant current controlled forward converter circuit in which the flyback DCDC converter in FIG. 5 is replaced with a forward DCDC converter.

These resonant current control type DCDC converters, including buck-boost type DCDC converter, step-down type DCDC converter, flyback type DCDC converter, and forward type DCDC converter, convert current from charging voltage of resonant capacitor Cr to inductor Ld while switch S is on. The current in the inductor Ld continues to flow to the load side by the ON/OFF signal, but the next resonant current operation can be started when the current from the resonant capacitor Cr is turned off.

FIG. 8 is a basic circuit configuration of a resonant current control type DCDC converter, which schematically represents the basic operation of a DCDC converter that controls on and off the current from the resonant capacitor Cr.

Figure 9 shows the operating waveforms when the conduction width Ton1, Ton2 (>Ton1) of the switch S of the resonant current control type DC/DC converter is changed. a) When the current width is small, the differential voltage ΔE due to the voltage drop of the resonant capacitor Cr is small, and the pulse current id2 and average current io that flow into the load side when the resonant current ir and the switch S are turned off also become small. However, b) indicates that as the conduction width increases, both the resonant current ir and the load current Io increase.

The resonant current controlled DC power supply of the present invention has a circuit configuration in which the DC power supply or the AC power supply is connected not directly to the DC/DC converter through an LC resonant circuit, but its effects will be described below.

Figure 10 shows a schematic diagram of the configuration of a resonant current controlled DC power supply that converts a DC power supply into the required DC voltage, and Figure 11 shows the voltage Es on the DC power supply side, the resonance current ir, and the waveforms of the power supply current waveform is. It shows.

By using an LC resonant circuit, the pulsed current caused by the switching control of the DCDC converter does not flow to the power supply side, and the smooth waveform resonant current ir of the LC resonant circuit flows, so a small LC DC power supply filter is inserted . Therefore, the inflow current is becomes the average current of the resonant oscillation current with less noise .

Figure 12 shows a schematic diagram of the configuration of a resonant current controlled DC power supply that rectifies an AC power supply and converts it into the required DC voltage, and Figure 13 shows the voltage es on the AC power supply side, the resonance current ir, and the power supply current waveform. The is waveform is shown.

In this case, the rectified voltage waveform becomes the absolute value waveform of the sine wave AC power supply voltage, and a resonant current ir proportional to the voltage amplitude flows, but the current is on the AC side is changed by the AC power supply filter using a small LC.
A sine wave current having the same waveform as the AC power supply voltage can be obtained without special PFC control.

When a voltage rectified from an AC power source is directly connected to a DC/DC converter without going through an LC resonant circuit, a pulsed current due to switching control of the DC/DC converter flows directly to the AC line.

Figure 14 is a schematic diagram of the configuration of a resonant current controlled DC power supply that rectifies a three-phase balanced AC voltage with a three-phase bridge circuit and converts the voltage output through a small LC filter circuit into the required DC voltage. In this case, the AC power supply current is has a current waveform close to a square wave with a 120 degree conduction width as shown in the figure.

In addition, by using an LC resonant circuit, a current proportional to the voltage difference between the DC side power supply voltage and the voltage of the resonant capacitor normally flows, and excessive current is suppressed to a current determined by the power supply voltage and the LC resonant circuit constant. be able to.

Further, since the voltage applied to the switching element of the DC/DC converter is turned off when the voltage of the resonant capacitor becomes low, effects such as being able to be suppressed to a low level can be expected.

As described above, in addition to the excellent features of (Patent Document 7), the present invention can be configured without using a resonance switch, so loss as a switch and generation of noise itself can be eliminated, and the main circuit The configuration and drive circuitry can also be further simplified.

Here, the features of the resonant current controlled DC power supply according to the present invention will be summarized below.

1) By simply controlling the current width of the switch at a fixed frequency using one switch, it is possible to control any DC output voltage and current while improving the power supply current waveform and characteristics.
2) The control system including the main circuit configuration and drive circuit is extremely simple,
3) Switching noise and switching loss can be significantly reduced compared to the power supply that controls the configuration using two switches (Patent Document 7).
4) If the DC-DC converter section is a buck-boost type DC-DC converter, the voltage control range is wide, so it can easily correspond to worldwide AC power supply voltages.
5) Furthermore, since a transformer is used in a configuration using a flyback type DC/DC converter, an isolated DC output can be obtained.
6) Due to the transformation ratio design, it can be easily applied as a small switching power supply with low voltage and large current.
7) By passing the LC resonant circuit, it is possible to prevent the increasingly sharp switching component current in the DC/DC converter from flowing to the power supply side, and it is also effective as a countermeasure against EMI noise.
8) Switching of the DCDC converter section can be controlled to switch off at the moment when the resonant capacitor voltage is discharged and lowered, so the switch element breakdown voltage can be suppressed.
9) Since an LC resonant circuit is used in the DC power supply section, excessive current can be suppressed by the characteristic impedance of the LC resonant circuit.
10) If the DC/DC converter section is a step-down DC/DC converter, there will be restrictions on the output voltage control range, but the current peak value in the DCDC converter section will be suppressed, and an improvement in efficiency can be expected.

Resonant current control buck-boost DC/DC converter circuit Switching operation waveform of resonant current controlled buck-boost DC/DC converter circuit 1-switch resonant current control buck-boost DC/DC converter circuit Switching control operation waveform of 1-switch resonant current control type buck-boost DC/DC converter circuit Resonant current controlled flyback DC/DC converter circuit Resonant current control step-down DC/DC converter circuit Resonant current control type forward DC/DC converter circuit Basic circuit of resonant current control type DC/DC converter Switching control operation waveform of resonant current controlled buck-boost DC/DC converter Main circuit configuration of resonant current controlled DC power supply Inflow current waveform of resonant current controlled DC power supply Main circuit configuration of single-phase resonant current controlled DC power supply Inflow current waveform of single-phase resonant current-controlled DC power supply Main circuit configuration of three-phase resonant DC power supply Operating waveform of resonant current controlled DC power supply (Es=100V, LED1, Ton=5us) Operating waveform of buck-boost direct control DC power supply (Es=100V, LED1, Ton=5us) Operating waveform of resonant current control step-down DC power supply (Es=100V, LED2, Ton=5us) Operating waveform of resonant current controlled flyback DC power supply (Es=100V, N1/N2=1,LED1,Ton=5us) Operating waveform of single-phase resonant flyback DC power supply (Va=100V, N1/N2=1, LED1, Ton=5us) Operating waveform of single-phase resonant flyback DC power supply (Va=200V, N1/N2=1, LED1, Ton=3us) Operating waveform of single-phase resonant flyback DC power supply (Va=100V, N1/N2= 20, R=10 ohm, Ton=3us) Operating waveform of three-phase resonant flyback DC power supply (Va=200V, N1/N2=1, LED1, Ton=3us)

In carrying out the present invention, the resonant current controlled DC power supply shown in FIG. 4) The input/output control operation of a DC power supply when a forward converter is applied will be confirmed using several simulation analysis results for the case where a full-wave rectified DC power supply and an AC power supply are connected.

The simulation analysis was performed under the following operating conditions.
The DC power supply voltage Es applied to the resonant current control type DC power supply is Es=100V, and when applying an AC power supply, the frequency of the AC power supply is fa=60Hz, and the AC voltage (effective value) Es(=Ea) is Es=100 V or 200V, the LC filter on the power supply side is La=0.5mH, Ca=2uF, the resonance inductance Lr is Lr=100 uH, the resonance capacitance Cr is Cr=0.1 uF, and the inductance Ld connected to the DCDC converter is: Ld=100uH, the inductance Lm of the flyback transformer is Lm=100uH, the transformation ratio of the transformer is N1/N2=1, the switching frequency fs of the switch for resonance operation and output control is fs=70 kHz, Further, the on time Ton of the switch was set from Ton=0 to 5 usec.

As a DC load circuit, the smoothing capacitor Cd connected to the load end is Cd=1000 uF, and the load is LED1 (resistance r _F =10 ohm, voltage drop V _F =165 V) or LED2 (resistance r _F = 5 ohm, voltage drop V _F =86 V) was connected for simulation analysis.

In addition, to confirm the operation of a low-voltage DC power supply, simulation analysis was performed by connecting the transformation ratio of the flyback converter to N1/N2=20, the smoothing capacitor Cd to Cd=4000 uF, and the resistance R to R=10 ohm. I did it.

(1) Operation of the buck-boost DC/DC converter Figure 15 shows the on-period of the switch of the resonant current control type DC power supply configured with the buck-boost DC/DC converter when the DC power supply voltage Es(vad) = 100V is Ton = 5 usec. , is the operating waveform when LED1 load is connected.

When the switch is turned off with respect to the current waveform id1 of the switch, a resonant current ir flows due to the resonant operation due to the voltage difference between the power supply voltage vad and the resonant capacitor voltage vr, and the output voltage is controlled by the switch conduction time. In this case, a DC input current is proportional to the output current is flowing, and due to the LC resonant circuit, the power supply current has a resonance with a peak value of 3.14A (3.61 times the DC output current) for the DC output current of 0.87A in this case. Confirms that current is flowing

Figure 16 shows the operating waveforms when the DC-DC converter is operated without the LC resonant circuit for comparison. Since the current flows linearly when the switch is turned on, the DC output current in this case is 0.74A. On the other hand, it is confirmed that a large power current flows, with a peak value of 4.86A (6.56 times the DC output current) .

(2) Step-down DC-DC converter operation Figure 17 shows that for a DC power supply voltage Es(vad) = 100V, the on-period of the switch of a resonant current-controlled DC power supply configured with a step-down DC-DC converter is set to Ton = 5 usec, and is low . Operating voltage LED2 This is the operating waveform when a load is connected.

At the point in time when the switch is turned off and the current waveform id1 becomes zero, it is confirmed that a resonant current ir is flowing due to the resonant operation due to the voltage difference between the power supply voltage vad and the voltage vr of the resonant capacitor.

(3) Flyback DC-DC converter operation Figure 18 shows a resonant current-controlled DC converter configured with a flyback DC-DC converter using a transformer with a transformation ratio N1/N2 = 1 for a DC power supply voltage Es(vad) = 100V. This is the operating waveform when the power switch on period is Ton=5usec and LED1 load is connected.

(4) Single-phase resonant flyback DC power supply operation In this case, the transformation ratio is set to N1/N2 = 1, so the results are the same as those of (1) buck-boost DC-DC converter operation, but the DC power supply A DC output is obtained that is isolated from the

In Figure 19, a single-phase full-wave rectified voltage waveform is applied from an AC power supply with an AC power supply voltage Es(vad) = 100V via an LC filter circuit, the transformation ratio N1/N2 = 1, and the on-period of the switch is Ton = 5usec. , LED1 This is the operating waveform as an ACDC converter when a load is connected.

Figure (a) shows the operating waveform as a resonant current control type ACDC converter, and Figure (b) shows the waveform where the AC power supply voltage is enlarged around the maximum value in order to confirm the switching operation. It is confirmed that the resonance current control IR, DC output voltage VO, and current IO can be controlled just by controlling the on-period of each switch, and at the same time, the power supply current IS has a beautiful sine wave.

Figure 20 shows the operating waveforms when the AC power supply voltage is Es(vad) = 200V and the switch on period is Ton = 3usec to reduce the output. Since the current id1 becomes smaller, the voltage drop of the resonant capacitor Cr is less and the pulsation width is reduced, and at the same time, the amplitude of the resonant current ir is also reduced, the voltage of the resonant capacitor is lowered, and it is confirmed that the voltage applied to the switch element is also lowered. can.

(5) Operation of single-phase resonant flyback DC power supply Figure 21 shows that in order to make the resonant current control type DC power supply work as a low DC power supply, the AC power supply voltage is Es(vad)=100V, the transformation ratio N1/N2=20, The operating waveforms are shown when the smoothing capacitor Cd is 4000uF and the switch on period is Ton=3usec.

The resonant current control type DC power supply of the present invention can perform LC resonance operation and control the necessary DC voltage and current with only one switch, and at the same time can make the inflow current waveform of the power supply device a sine wave, so it can be used as a normal DC power supply. In addition, it can be expected to have excellent characteristics as a low-voltage, high-current power supply.

(6) Operation of three-phase resonant flyback DC power supply Figure 22 shows a three-phase AC power supply with Es=200V rectified by a three-phase full-wave rectifier circuit and then passed through an LC filter circuit to a resonant current control type AC power supply. This is the operating waveform of the power supply device with the configuration shown in Figure 14 in addition to the DC/DC converter. The current waveform has a conduction width close to a square wave, and it can be confirmed that the power factor can be significantly improved compared to the case of a capacitor input type rectifier circuit.

(7) Forward ACDC converter operation
By adding the full-wave rectified output from the AC power supply as the DC power supply section of the resonant current control type forward DC-DC converter circuit shown in Figure 7, forward ACDC converter operation can be performed, and isolated output can be achieved through the transformer. can be obtained.

However, for loads in which a smoothing capacitor is connected to an LED load or a DC load due to step-down operation, the AC current waveform does not flow in the area where the power supply voltage is low, and the current waveform is reverse biased. It has been confirmed that it operates with a high fundamental power factor.

100...power supply 100 -1...DC power supply 100 -2...single-phase AC power supply 100 -3...three-phase AC power supply 110...filter circuit 110 -1...AC filter 110 -2...DC filter 120...diode bridge circuit 120 -1... Single-phase diode bridge circuit 120 -2... Three-phase diode bridge circuit 200... Resonant DC-DC converter 210... Directional switch circuit 210 -1... Switch 210 -2... Diode 220... LC resonance circuit 120 -1... Resonant inductor Lr
120 -2...Resonance capacitor Cr
120 -3... Reverse charging prevention diode 230... Inductor current switch circuit 230 -1... Buck-boost chopper circuit 230 -2... Flyback DC-DC converter circuit 230 -3... Step-down chopper circuit 230 -4... Forward DC-DC converter Circuit 240... Transformer circuit 240 -1... Transformer 240 -2... Snubber circuit 300... DC load circuit 300-1... Smoothing capacitor 300-2... DC load (resistance, LED)

Claims (3)

An LC resonant circuit in which a resonant inductor Lr and a resonant capacitor Cr, in which a reverse charge prevention diode is connected in anti-parallel as necessary, are connected in series to the DC power source via a reverse current prevention diode as necessary, and the resonant A DC-DC converter using a buck-boost chopper circuit or a buck chopper circuit composed of a switch S, an inductor Ld, and a diode was connected to both ends of the capacitor Cr, and a smoothing capacitor Cd was connected in parallel to the DC-DC converter. In the circuit configuration that connects the DC load,
By controlling the switching pulse width of the switch S in synchronization with the resonant period of the LC resonant circuit, only one switch can control the resonant current of the LC resonant circuit and the voltage and current to the DC load. A resonant current control type DC power supply characterized by enabling.
In the resonant current controlled power supply according to claim 1, the buck-boost chopper circuit constituting the DC-DC converter includes a primary winding of the transformer 1 and the switch S connected in series across the resonance capacitor Cr. One end of the secondary winding of the transformer 1 is connected to a smoothing capacitor Cd1 via a reverse current prevention diode, and the other end of the secondary winding of the transformer 1 is connected to the other end of the smoothing capacitor Cd1 . The step-down chopper circuit has a circuit configuration of a flyback type DC-DC converter in which a DC load is connected to both ends of the smoothing capacitor Cd1 , and the primary winding of the transformer 2 is connected to both ends of the resonant capacitor Cr. The switches S are connected in series, and one end of the secondary winding of the transformer 2 is connected to a smoothing capacitor Cd2 via a backflow prevention diode, a free-wheeling diode, and a smoothing inductor Ld. A circuit configuration of a forward type DC-DC converter in which a smoothing capacitor Cd2 and the other end of the free-wheeling diode are connected to the other end of the secondary winding of the transformer 2 , and a DC load is connected to both ends of the smoothing capacitor Cd2 . year,
A resonant current control type DC power supply characterized in that both of them are configured using a transformer, thereby making it possible to achieve significant voltage control and to obtain a DC output isolated from the DC power supply.
In the resonant current controlled power source according to claims 1 and 2, the DC power source is configured from an AC power source via a full-wave rectifier circuit, and the switching pulse width is controlled by the switch S.
When the AC power source is a single-phase sine wave, an AC filter circuit is provided on the AC side of the full-wave rectifier circuit to remove a resonant frequency component of the resonant current, thereby making the AC current waveform sinusoidal;
When the AC power source is a three-phase balanced sine wave, a DC filter circuit for removing resonance frequency components is provided on the DC output side of the full-wave rectifier circuit to create a square wave AC current waveform with a 120-degree conduction width. ,
A resonant current control type DC power supply, characterized in that it is possible to control voltage and current to the DC load.

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