JPH0993947A - Power unit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a power unit which can be downsized and also which can improve conversion efficiency and besides can reduce generated higher harmonic components. SOLUTION: This power unit is equipped with a capacitive element 4 capable of being connected to a DC power source 2, a first switching means 42 for forming a first closed loop circuit where at least the capacitive element 4 and the DC power source 2 are connected in series, a second switching means 4 for forming the second closed loop circuit including the series resonance circuit of at least the capacitive element 4 and the inductive element 43, and a switch control means for operating the first and second switching means 42 and 43 alternately. And, the circuit frequency based on the series resonance circuit, the switch is set to the frequency higher than the repeat frequency that the switch control means operates the first switching means 42, and when the second switch 41 is operated by the switch control means at least, AC power based on the resonance of the series resonance circuit is outputted from the second closed loop circuit.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power supply device for converting DC power into AC power or DC power having a predetermined voltage value.

[0002]

2. Description of the Related Art As this type of power supply device, a flyback type switching regulator shown in FIG. 16 is known. The switching regulator 51 uses the DC power supply 5
2, a transformer 53, a FET 54, a diode 55 and a capacitor 56. In this switching regulator 51, when a control signal VCont having a predetermined switching frequency is input to the gate of the FET 54, the FET 54
Turns on / off at that switching frequency. In this case, when the FET 54 is turned on, a rectangular wave voltage is applied to the primary coil 53a of the transformer 53, and generally a triangular wave current flows to accumulate energy in the primary coil 53a. Next, when the FET 54 is turned off, the energy accumulated in the primary coil 53a is released, an induced voltage is generated in the secondary coil 53b at this time, and an alternating current flows in the secondary coil 53b based on this induced voltage. DC current is generated by rectifying and smoothing this current by the diode 55 and the capacitor 56. On the other hand, in recent switching regulators, there is a demand for downsizing of devices. Therefore, in the conventional switching regulator 51, the transformer 53 is increased by increasing the switching frequency of the control signal VCont.
It is possible to reduce the size of the device, and as a result, the size of the entire device is reduced.

[0003]

However, the conventional switching regulator 51 has the following problems. That is, when the device is further downsized by increasing the switching frequency, the switching loss caused by the delay time at the turn-on and turn-off of the FET 54 also becomes large, and as a result, the conversion efficiency is lowered. . In addition, since the voltage waveform applied to the transformer 53 is a rectangular wave, the transformer 5 is affected by the core loss due to the influence of its harmonic component.
There is a problem in that the loss within 3 becomes large and the conversion efficiency of the device decreases. Further, the harmonic component is conducted and radiated as unnecessary radiation noise, so that there is a problem that it has a great influence on other devices.

On the other hand, by making the waveform of the current flowing through the transformer 53 or the waveform of the voltage applied to the transformer 53 a sine wave, so-called zero current switching or zero voltage switching is enabled to reduce the switching loss. Type switching power supplies also exist. However, even with this resonance type switching power supply device, it is impossible to eliminate switching loss at all.
There is still the problem that the conversion efficiency cannot be increased above a certain level.

The present invention has been made in view of the above problems, and can reduce the size of the device, improve the conversion efficiency, and reduce the generated harmonic component. The purpose is to provide.

[0006]

In order to achieve the above-mentioned object, a power supply device according to a first aspect of the present invention is a first power supply device in which a capacitive element connectable to a DC power supply and at least a capacitive element and a DC power supply are connected in series. First switch means for forming a closed loop circuit; second switch means for forming a second closed loop circuit including at least a series resonant circuit of a capacitive element and an inductive element; Switch control means for alternately activating the two switch means, wherein the circuit frequency based on the series resonance circuit is set to a frequency higher than the repetition frequency at which the switch control means operates the first switch means, and at least the switch control means. By the second
The second closed loop circuit outputs alternating current power based on the resonance of the series resonant circuit when the switch is activated. In this case, the circuit frequency means the resonance frequency of the series resonant circuit when the load is not connected to the output AC power, and the unique frequency including the load in the series resonant circuit when the load is connected. Refers to the frequency. Therefore, in this specification, the circuit frequency is used to include both.

In this power supply device, when the switch control means operates the first switch means, a first closed loop circuit in which the capacitive element and the DC power supply are connected in series is formed.
At this time, the current from the DC power source flows into the closed loop circuit, and energy is stored in the capacitive element. The switch control means then deactivates the first switch means and activates the second switch means. As a result, a second closed loop circuit including a series resonance circuit of the capacitive element and the inductive element is formed. In this case, the second closed loop circuit is in a resonance state due to the series resonance circuit, and charge is transferred from one terminal of the capacitive element in which energy is stored to the other terminal through the inductive element. Moving. When all the charges move, on the contrary, the charges move toward one terminal. In this closed loop circuit, these operations are repeated one after another. On the other hand, in this state, for example, if a load is connected to both ends of either the capacitive element or the inductive element, AC power having a frequency equal to the circuit frequency is output to the load. In this case, since the circuit frequency is higher than the repetition frequency at which both the first switch means and the second switch means operate once, if the first switch means operates once, the capacitive element Charging / discharging is performed at least once. That is,
If the first switch means operates once, it is possible to output AC power for one cycle or more. As described above, when the conventional switching power supply device outputs AC power corresponding to one cycle of the switching frequency, one switching loss is always generated, whereas in this power supply device, one switching loss is generated. While it occurs, it is possible to output AC power corresponding to one cycle or more of the circuit frequency. As a result, the switching loss can be reduced as compared with the conventional switching power supply device, which can improve the conversion efficiency. In addition, since the second closed loop circuit forms a series resonance circuit, the current flowing in the closed loop circuit has a sinusoidal resonance waveform, which may reduce the core loss of the inductive element. In addition to that, the generation of noise can be significantly reduced.

According to a second aspect of the present invention, there is provided a power supply device in which a first switch means for forming an inductive element connectable to a DC power source and a first closed loop circuit in which at least the inductive element and the DC power source are connected in series. And a second switch means for forming a second closed loop circuit including at least a series resonance circuit of an inductive element and a capacitive element, and the first switch means which is connected in parallel to the second switch means. And a current control means for preventing the direct current of the DC power source from flowing into the capacitive element and for moving the energy stored in the inductive element to the capacitive element when the first switch means stops operating. , A switch control means for alternately activating the first and second switch means, wherein the circuit frequency based on the series resonant circuit is such that the switch control means activates the first switch means. It is set to a frequency higher than the repetition frequency, when the second switch is actuated by at least the switch control means, and outputs the AC power based on the resonance of the series resonant circuit from the second closed loop circuit.

In this power supply device, when the switch control means activates the first switch means, a first closed loop circuit in which an inductive element and a DC power supply are connected in series is formed.
At this time, the current from the DC power source flows into the closed loop circuit, and energy is stored in the inductive element. The switch control means then deactivates the first switch means, which causes the energy stored in the inductive element to be transferred to the capacitive element by the current control means. The switch control means then actuates the second switch means, thereby forming a second closed loop circuit including a series resonant circuit of the inductive element and the capacitive element. After that, the conversion efficiency can be improved by outputting the AC power from the second closed loop circuit in the same manner as the power supply device according to the first aspect.

According to a third aspect of the present invention, in the power source apparatus according to the second aspect, the second switch means and the current control means are integrally constructed by an N-channel MOS-FET. .

In this power supply device, the N-channel MOS-
Since the internal diode of the FET itself functions as the current control means and the switching operation of the N-channel MOS-FET constitutes the second switch means, the configuration can be simplified.

According to another aspect of the power supply apparatus of the present invention, a series resonance circuit formed of at least an inductive element and a capacitive element and connectable to a DC power supply, and a first closed loop in which the series resonance circuit and the DC power supply are connected in series. A first switch means for forming a circuit, a second switch means for forming a second closed loop circuit including at least a series resonant circuit, and a switch for alternately activating the first and second switch means. And a circuit frequency based on the series resonant circuit is set to a frequency higher than a repetition frequency at which the switch control means operates the first switch means, and at least when the second switch is operated by the switch control means. In addition, AC power based on the resonance of the series resonance circuit is output from the second closed loop circuit.

In this power supply device, the conversion efficiency can be improved in the same manner as the power supply device according to the first aspect. In this case, in this power supply device, the inductive element can limit the current flowing into the capacitive element to a predetermined value when the first closed loop circuit is formed.

A power supply device according to a fifth aspect is the power supply device according to any one of the first to fourth aspects, wherein the inductive element is a primary coil of the transformer and the second closed loop circuit is a secondary coil of the transformer. It is characterized in that AC power is output from the coil.

In this power supply device, the conversion efficiency can be improved similarly to the power supply device according to the first or second aspect. In this case, in this power supply device, an AC voltage or an AC power is induced in the secondary coil by the current flowing in the primary coil of the transformer connected in the second closed loop circuit, so that it is isolated from the second closed loop circuit. AC power can be easily output to the circuit.

According to a sixth aspect of the present invention, in the power source apparatus according to any one of the first to fifth aspects, the first closed loop circuit includes current limiting means for limiting a current flowing from the DC power source to a predetermined value. It is characterized by

In this power supply device, when the first closed loop circuit is formed, the current limiting means limits the current value flowing from the DC power supply to either one of the capacitive element and the inductive element to a predetermined value. To do. Therefore, the time for accumulating electric charges in the element and the circuit frequency of the second closed loop circuit can be set independently and independently, so that the circuit design can be facilitated.

According to a seventh aspect of the present invention, in the power source apparatus according to the sixth aspect, the current limiting means is a choke coil.

In this power supply device, since the choke coil is the means for limiting the current flowing through either one of the elements when the first closed loop circuit is formed, the loss caused by the flowing current is prevented.

According to an eighth aspect of the present invention, in the power source apparatus according to any one of the first to seventh aspects, the power source apparatus further comprises rectifying / smoothing means for rectifying / smoothing the AC power to convert it into DC power. Characterize.

In this power supply device, AC power is converted into DC power by the rectifying / smoothing means, so that an efficient DC-DC converter is provided.

A power supply device according to a ninth aspect is the power supply device according to any one of the first to eighth aspects, further comprising detection means for detecting at least one of a voltage value and a current value of the AC power, and the switch control means. The first switch means is operated based on the detection value of the detection means.

In this power supply device, when the charge in the second closed loop circuit is consumed as AC power by the load, the voltage value or current value of the AC power output from the second closed loop circuit decreases. In this case, the detection unit detects it, and the switch control means determines the first value based on the detected value.
To activate the switch means. As a result, new energy is stored in the first closed loop circuit, and the second switch means is actuated to output AC power based on the new energy. In this way, energy based on the charge of the DC power supply can be automatically stored in the first closed loop circuit according to the voltage value or current value of the output AC power.

According to a tenth aspect of the present invention, in the power source apparatus according to the eighth aspect, there is provided detection means for detecting at least one of a voltage value and a current value of the DC power source, and the switch control means has a detection value of the detection means. The first switch means is operated based on

In this power supply device, almost the same as the power supply device according to the ninth aspect, it is possible to automatically store the energy based on the electric charge of the DC power supply in the first closed loop circuit. In this case, since this power supply device is provided with the rectifying / smoothing means for configuring the DC / DC converter, its output may be detected. As a result, the configuration of the detection means itself is simpler than that of the power supply device according to claim 9.

A power supply device according to an eleventh aspect includes a first closed loop circuit formed by the first switch means according to the fifth aspect and a second closed loop circuit formed by the second switch means. A closed loop circuit group having a plurality of sets; and a switch control means for alternately activating the first and second switch means in the closed loop circuit group, wherein the secondary coil of each transformer of the closed loop circuit group has an annular connection and a star shape. The switch control means is configured to be connected to any one of the connections to output AC power, and the switch control means shifts the operation timings of at least the respective second switch means of the plurality of sets from each other.

In this power supply device, for example, by using the AC power output from each of the three second closed loop circuits, the DC power can be converted into the three-phase AC power. Therefore, the three-phase alternating current can be directly supplied to the three-phase motor or the like.

A power supply device according to a twelfth aspect of the present invention is the power source device according to the eleventh aspect.
The power supply device described above is characterized by further comprising rectifying means for rectifying the AC power by being connected to each secondary coil connected.

In this power supply device, the AC power output from each of the plurality of second closed loop circuits is rectified by the rectifying means to generate DC power. In this case, the operation timings of the respective second switch means in each set are mutually shifted by the switch control means.
As a result, the circuit frequency components are superimposed on the DC power in a state where they are shifted as ripple voltages, so that the ripple voltage can be easily removed by, for example, a smoothing capacitor.

A power supply device according to a thirteenth aspect is the eleventh aspect.
Alternatively, in the power supply device described in Item 12, the switch control means shifts the operation timings of the second switch means from each other by a phase difference of a value obtained by dividing 2π by the number of sets.

In this power supply device, DC power is converted into symmetrical polyphase AC power. Further, in this case, the component of the ripple voltage superimposed on the DC power rectified by the rectifying means appears on average for each phase difference of a value obtained by dividing 2π by the number of pairs. Therefore, for example, if the number of sets is increased, the smoothing capacitor can be omitted and the DC power can be directly supplied to the load. Further, even if the number of sets is reduced, the ripple voltage can be easily removed by the small-capacity smoothing capacitor, so that the device can be downsized.

A power supply device according to a fourteenth aspect is the eleventh aspect.
13. The power supply device according to any one of 1 to 13, further comprising a detection unit that detects at least one of a voltage value and a current value of the AC power, and the switch control unit includes each of the closed loop circuit groups based on the detection value of the detection unit. It is characterized by activating one switch means.

In this power supply device, substantially the same as the power supply device according to the ninth aspect, it is possible to automatically store the energy based on the electric charge of the DC power supply in each first closed loop circuit.

According to a fifteenth aspect of the present invention, in the power source apparatus according to any one of the first to fourteenth aspects, the first closed loop circuit includes a backflow current blocking means for blocking a backflow of current to the DC power supply. It is characterized by

In this power supply device, the direction of current flow in the first closed loop circuit is determined only in one direction when the first switch means is operating. Therefore, when a series resonant circuit of a capacitive element and an inductive element is formed in the first closed loop circuit, the voltage based on the charge accumulated in the capacitive element is theoretically the power source of the DC power source. It is twice the voltage. As a result, the power that resonates when the second closed-loop circuit is formed by the second switch means becomes large, and a larger AC power can be output.

According to a sixteenth aspect of the present invention, in the power source apparatus according to any one of the first to fifteenth aspects, the switch control unit controls the operating time of the first switch means and the operating time of the second switch means. It is characterized in that the duty ratio of is changed.

In this power supply device, the switch control section keeps the operation cycles of the first and switch means fixed,
The operation time of the first switch means is changed. This allows the output AC power amount to be freely controlled.

[0038]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of a power supply according to the present invention will be described below with reference to the accompanying drawings.

First, a specific circuit of the power supply device will be described with reference to FIG. The figure shows a block diagram of the power supply device 1, which includes a DC power supply 2, a transformer 3, a charge storage capacitor (capacitive element) 4, and an FE.
T (first switch means, second switch means) 5,
6, diode (reverse current blocking means) 7, diode bridge (rectifying means) 8, smoothing capacitor (smoothing means)
9, control unit (switch control means) 10 and resistors 11 to 11
14 are provided.

In the power supply device 1, when the control signal VCont1 is output from the control unit 10, the FET 6 is turned on, and the DC power supply 2, the primary coil 3a of the transformer 3, the charge storage capacitor 4, the diode 7 and the FET 6 are connected in series. A closed loop circuit for charge storage (first closed loop circuit) is formed. In this closed loop circuit, the current from the DC power supply 2 is input to the charge storage capacitor 4, and the charge is stored there. The charge storage capacitor 4
The current value input to is limited to a predetermined value by the inductance value of the primary coil (inductive element) 3a of the transformer 3. On the other hand, when the output of the control signal VCont1 from the control unit 10 is stopped, the FET 6 is turned off, and the closed loop circuit for charge storage becomes an open loop circuit with the charge stored in the charge storage capacitor 4.

After that, the control signal VCont2 is output from the control unit 10.
Is output, the FET 5 is turned on, and a closed loop circuit for discharging charges (second coil) formed by a series circuit of the primary coil 3a of the transformer 3, the charge storage capacitor 4, and the FET 5
Closed loop circuit) is newly formed. In this closed loop circuit, a series resonance circuit is formed by the primary coil of the transformer 3 and the charge storage capacitor 4, and the terminal 4a from which the charge of the charge storage capacitor 4 is stored goes to the other terminal 4b. The charge moves. On the other hand, terminal 4b
When the electric charge moves to, the electric charge moves to the terminal 4a. By repeating these operations one after another, a current flows in the primary coil 3a of the transformer 3, and an induced voltage induced by this current or an alternating current signal, which is an induced current, appears in the secondary coil 3b of the transformer 3. This AC signal is converted into DC power by being rectified by the diode bridge 8 and smoothed by the smoothing capacitor 9. In this way, the control unit 10 repeatedly outputs the control signals VCont1 and VCont2 at a predetermined cycle, whereby a DC-AC inverter device is realized. The circuit frequency of the closed loop circuit for discharging electric charges is determined mainly based on the inductance value of the primary coil 3a of the transformer 3 and the capacitance value of the electric charge storage capacitor 4, and the control signals VCont1 and VCont2 are output. It is determined that the frequency becomes higher than the repetition frequency. Also, control signals VCont1 and VCont2
Is not always constant, the control unit 1
0 detects a detection voltage (detection value) based on the voltage or current of DC power or AC power, and when the detection voltage rises above a predetermined reference voltage, the transformer 3 stops by outputting the control signal VCont2. It may be configured to limit the transmitted AC power.

Next, a more specific operation of the power supply device 1 will be described with reference to FIG. When the control signal VCont1 is output from the control unit 10, the FET 5 is turned on (see reference numeral 15 in FIG. 9A). In this state, a closed loop circuit for charge storage is formed, and the voltage of the terminal 4a with respect to the terminal 4b of the charge storage capacitor 4 (hereinafter, referred to as "both-end voltage") is as shown in FIG. 2 rises to a voltage exceeding the power supply voltage Vin. In this case, the voltage across the charge storage capacitor 4 becomes higher than Vin because the closed loop circuit for charge storage forms a series resonance circuit of the primary coil 3a of the transformer 3 and the charge storage capacitor 4. This is because, theoretically, the voltage rises to twice the voltage Vin. However, due to the load on the secondary coil side of the transformer 3 and the load Q of the closed loop circuit for charge storage, the voltage at both ends is actually less than twice the voltage Vin.

In the power supply device 1, even if the voltage across the power supply device becomes higher than the voltage Vin, the diode 7 blocks the reverse flow of the current, so that no current flows from the terminal 4a to the DC power supply 2 side. The charge storage capacitor 4 maintains the equilibrium state in which the high voltage is applied to both ends. Also,
In this charge storage operation, the charge storage capacitor 4
The secondary coil 3 of the transformer 3 when current is flowing through
At both ends of b, 1/2 of the circuit frequency based mainly on the time constant of the charge storage capacitor 4 and the primary coil 3a of the transformer 3
In the equilibrium state in which a waveform corresponding to the period (see reference numeral 16 in FIG. 4D) appears and the current is not flowing, the secondary coil 3
No voltage appears across b. Specifically, at the start of charging, a steep rising voltage appears in the secondary coil 3b, and the voltage value gradually decreases. Next, when charge is accumulated in the charge storage capacitor 4 and the voltage across the capacitor reaches the voltage Vin, the DC voltage of the DC power supply 2 and the voltage across the capacitor 4 become equal, so the voltage across the secondary coil 3b becomes 0V. Become. However, in this state, the current is still flowing through the primary coil 3a of the transformer 3 and the energy is accumulated therein. Therefore, the current flowing by the primary coil 3a causes the current to flow until the energy disappears. Flows. As a result, a negative voltage appears across the secondary coil 3b. Then, when the current flowing through the charge storage capacitor 4 disappears, the energy of the primary coil 3a disappears and the amount of charge is maximized, the voltage across the secondary coil 3b becomes 0V.

Next, when the output of the control signal VCont1 is stopped and the control signal VCont2 is output from the control unit 10,
The FET 6 is turned on (see reference numeral 17 in FIG. 7B). In this state, a closed loop circuit for discharging charges is formed, and the closed loop circuit forms a resonance circuit based on the inductance of the primary coil 3a of the transformer 3 and the capacitance of the charge storage capacitor 4. Therefore, a current according to the waveform of the circuit frequency starts flowing from the terminal 4a of the charge storage capacitor 4 to the terminal 4b. Specifically, a current flows from the terminal 4a to the terminal 4b, and the voltage at both ends is 0.
Even in the state of V, since the current still flows in the primary coil 3a of the transformer 3 and the energy is accumulated, the energy disappears by the action of the primary coil 3a trying to flow the current. Current flows up to. As a result, the voltage on the terminal 4b side becomes higher than the voltage on the terminal 4a side. When the current has finished flowing to the terminal 4b, on the contrary, the current starts to flow toward the terminal 4a, and finally all the charges move toward the terminal 4a. In the closed loop circuit, these resonance operations are repeated. At this time, an alternating current as indicated by reference numeral 18 in FIG. 6C flows through the secondary coil of the transformer 3, and this alternating current is output from the secondary coil 3b as alternating current power. This AC power is rectified by the diode bridge 8 and smoothed by the smoothing capacitor 9 to become DC power.

As described above, while the FET 5 is on, the AC power based on the power resonating in the closed loop circuit for discharging charges is at least one cycle or more, and the transformer 3 is used.
Is output from the secondary coil of. This is the control signal VCont
1 represented by the sum of the output time of 1 and the output time of VCont2
In the cycle, it means that, during one cycle in which the FET 5 switches once, the AC power having the circuit frequency that is approximately equal to the resonance frequency is output for one cycle or more. Therefore, when the conventional switching power supply device outputs AC power corresponding to one cycle of the switching frequency, one switching operation is always performed to cause one switching loss. It is possible to output AC power having a circuit frequency for one cycle or more while one switching loss occurs. As a result, FE
If, for example, N cycles or more of the circuit frequency are output within one cycle in which T5 operates, it means that the switching loss becomes 1 / N or less, and the switching loss is significantly reduced compared to the conventional switching power supply device. It is possible to improve the conversion efficiency.

Further, since the closed loop circuit for discharging electric charge forms a series resonance circuit, the current flowing in the closed loop circuit has a sinusoidal resonance waveform, which reduces the core loss in the transformer 3. In addition to the above, the generation of noise can be significantly reduced. Further, by increasing the circuit frequency in the closed loop for discharging charges, the inductance value of the primary coil 3a of the transformer 3 can be reduced, and as a result, the transformer can be downsized. Further, the FETs 5 and 6 are in a state in which a voltage or current applied to the FETs 5 and 6 is at a value 0 or at a level very close to the value 0 during a transition period in which the FETs 5 are changed from ON to OFF, and so-called zero volt or zero amp switching. Works with. Therefore, compared to the switching operation of the conventional pulse voltage / current switching regulator, it is possible to reduce the switching loss generated by one-time switching.
Further, by using the transformer 3 in the closed loop circuit for discharging electric charges, the diode bridge 8 as the secondary circuit and the DC power supply 2 as the primary circuit can be easily insulated.

Further, in this power supply device 1, when the FET 6 is operating, the direction of current flow in the closed loop circuit for discharging charges is determined by the diode 7 in only one direction, so that charge accumulation The voltage across the charge storage capacitor 4 theoretically becomes twice the power supply voltage Vin of the DC power supply 2 due to the series resonance circuit of the working capacitor 4 and the primary coil 3a of the transformer 3. As a result, the electric power that resonates when the closed loop circuit for discharging electric charges is formed by the FET 5 becomes large, and a larger AC power can be output.

FIG. 5 shows the signal waveforms of the respective parts corresponding to FIG. 4 when the diode 7 in FIG. 1 is short-circuited (equivalent to the omission of the diode 7). In this case, when the amount of charge stored in the charge storage capacitor 4 becomes maximum, the voltage across the terminal 4a of the charge storage capacitor 4 becomes higher than the power supply voltage Vin when the diode 7 is connected. Is the same.
However, in this case, a current flows from the terminal 4a of the charge storage capacitor 4 to the terminal 4b via the DC power supply 2 as indicated by reference numeral 19 in FIG. And
When electric charge is accumulated in the terminal 4b, on the contrary, a current again flows toward the terminal 4a, and these operations are repeated. The repetition frequency in this case is substantially equal to the resonance frequency of the series resonance circuit of the inductance of the primary coil 3a of the transformer 3 and the capacitance of the charge storage capacitor 4. Then, in the secondary coil 3b of the transformer 3, AC power having a frequency substantially equal to this resonance frequency appears. As described above, when the diode 7 is short-circuited, the AC power can be output not only when the closed loop circuit for discharging the charge is formed but also when the closed loop circuit for the charge storage is formed. It will be possible.

Further, the control unit 10 can change the duty ratio of the operating times of the FETs 5 and 6 without changing one cycle of the operating time thereof. In this case, the output AC power amount can be freely controlled.

Next, a modified embodiment of the power supply device 1 will be described with reference to FIGS. As shown in the figure,
The power supply device 31 is basically provided with three sets of a closed loop circuit for charge storage and a closed loop circuit for charge discharge of the power supply device 1 in FIG. 1 (corresponding to a closed loop circuit group). By shifting the phases of the control signals VCont1 and VCont2 by 120 degrees, the structure of the rectifier circuit is simplified. That is, the peak-to-peak value of the ripple voltage of the DC power output from the diode bridge 32 is reduced, whereby the rectifying capacitor 33 is reduced.
It is possible to reduce or eliminate the capacity value of. Note that the power supply device 1 among the components shown in FIG.
The same reference numerals are used for the same components as those of the above, and the description thereof will be omitted.

In the power supply device 31, the secondary coils 3b of each transformer 3 are annularly connected to form a closed loop circuit, and each connection point of each secondary coil 3b is connected to the anode of each diode of the diode bridge (rectifying means) 32. Each is connected. In this power supply device 31, the AC power output from each of the three closed loop circuits for discharging electric charge is rectified by the diode bridge 32 to generate DC power. In this case, each FET 5,
As shown in FIG. 7, the operation timing of 6 is the control unit 10
It is shifted by 120 degrees. As a result, the diode bridge 3 when the capacitor 33 is removed
A DC voltage as shown in FIG. 8 is output to the output of 2. A ripple voltage obtained by shifting the circuit frequency component of the series resonance circuit in the closed loop circuit for discharging charges by 120 ° is superimposed on the DC voltage. When the ripple voltage is further reduced, since the ripple frequency is high and the ripple current is small, it is possible to easily remove the ripple voltage by connecting a small-capacity smoothing capacitor in parallel between the output terminals. Therefore, the power supply device 31 can be downsized, and a smoothing capacitor having a small capacity may be used, so that the cost of the device can be reduced.

Further, the three transformers 3, 3, 3 are integrally manufactured, that is, the three primary coils 3a and the secondary coils 3b are simultaneously wound around one core to be manufactured integrally, thereby manufacturing the transformer. The cost can be further reduced. It should be noted that the capacitor 33 can be omitted if a slight ripple voltage is not a problem, and in this case, the power supply device can be further downsized. In addition, in this embodiment, an example having three groups has been described, but it is also possible to configure with four or more groups. In such a case, the control unit 10 controls the control signal V
It is sufficient to output Cont1 and VCont2 for each phase difference of a value obtained by dividing 2π by the number of pairs. When the number of sets is large, the smoothing capacitor 33 can be omitted and can be directly supplied to the load as DC power. Furthermore, without using the diode bridge 32, the DC-
It can also be used as an AC converter. Further, each secondary coil 3b may be connected in a star shape.

Further, the structure of the power supply device according to the present invention can be changed as appropriate. For example, FIGS. 2, 3, and 9 to 15 show operation principle diagrams showing other embodiments.
In this case, the FETs 5 and 6 in FIG. 1 are represented by switches 41 and 42 as an equivalent circuit, respectively, and the control unit 1
The description of 0 is omitted. Further, the transformer 3 is also represented by the coil 43 as an equivalent circuit, but in the present invention, as the AC power output transmission means, a coil is used to take out AC power from both ends of the AC power output transmission means without using a transformer. You can Further, the AC power can be taken out from both ends of the charge storage capacitor 4. However, in order to output only the AC power, it is preferable to take out the AC power via the capacitor 47 as shown in FIG. Further, in FIG. 1, the primary coil 3a of the transformer 3 limits the current when the charge is stored in the charge storage capacitor 4, but the present invention is not limited to this, and the current limiting coil may be provided separately. The current limiting coil in this case is represented by reference numeral 44. In this case, the time for accumulating charges in the charge accumulation element,
Since the circuit frequency of the closed loop circuit for discharging charges can be set independently and independently, the circuit design can be facilitated. Furthermore, the current limiting means is not limited to the choke coil, and may be a resistor or the like. However, it is preferable to use a choke coil (inductive element) in order to reduce the loss due to the current flowing for charge storage. Further, it is optional to provide the diode 7 for the reverse current element, and when provided, the diode 7 can be connected to any place where the function can be exerted. Also in these other embodiments, the power supply device 1 according to the embodiment in FIG.
DC power can be converted into AC power in the same manner as.

Further, as shown in FIG.
When energy based on the DC power supply 2 is stored in
When the switch 42 is turned off, an extremely large voltage is generated across the coil 43 in order to keep the current flowing through the coil 43. Therefore, the switch 42
It is necessary to move the current flowing in the coil 43, that is, the energy stored in the coil 43 to the energy storage means when the power is turned off. Therefore, as shown in the figure, by connecting the diode (current control means) 48 in parallel to the switch 41, a closed loop circuit of the coil 43, the capacitor 4 and the diode 48 is formed when the switch 42 is turned off. , Diode 48
Causes the current to flow into the capacitor 4 as the energy storage means in the same direction as the direction of the current flowing in the coil 43. As a result, the energy stored in the coil 43 is stored in the capacitor 4. Then switch 4
When 1 is turned on, a closed loop circuit for discharging charges is formed and a series resonance circuit of the coil 43 and the capacitor 4 is formed. At the same time, the diode 48 prevents the current from the DC power supply 2 from flowing into the capacitor 4 when the switch 42 is activated. Further, as shown in FIG. 11, the diode 48 and the switch 41 are operated based on the control signal VCont2 to operate an N-channel MOS-FE.
It can be integrally configured by T49. That is, the internal diode of the N-channel MOS-FET 49 itself functions as the diode 48, and the switching operation of the N-channel MOS-FET 49 constitutes the switch 41. In this case, the closed loop circuit for discharging charges can be easily configured.

[0055]

As described above, according to the power supply device of the present invention, the second closed loop circuit is formed during one cycle based on both the switching time of the first switch means and the switching time of the second switch means. In the above, since the capacitive element is charged and discharged at least once or more, the switching loss is reduced and the conversion efficiency is improved as compared with the conventional switching power supply in which one switching always causes one switching loss. be able to. Further, since the resonance frequency and the natural frequency in the second closed loop circuit can be set to high frequencies, the inductive element in the second closed loop circuit can be downsized. further,
According to the power supply device of the present invention, since the current waveform flowing through the inductive element in the second closed loop circuit is maintained as a sine wave by the series resonant circuit, the harmonic component is extremely small, and as a result, the inductive element The generation of core loss and noise can be almost eliminated.

[Brief description of drawings]

FIG. 1 is a block diagram of a power supply device according to an embodiment of the present invention.

FIG. 2 is an operation principle diagram of a power supply device according to another embodiment of the present invention.

FIG. 3 is an operation principle diagram of a power supply device according to another embodiment of the present invention.

FIG. 4 is a signal waveform diagram of each part for explaining the operation of the power supply device according to the embodiment of the present invention, FIG.
(B) shows the operation timing of the FET 5, (c) shows the voltage waveform across the charge storage capacitor 4, and (d) shows the voltage across the secondary coil 3b of the transformer 3. .

5A and 5B are signal waveform diagrams of respective parts for explaining the operation when the diode 7 is short-circuited in the power supply device according to the embodiment of the present invention, FIG. 5A is the operation timing of the FET 6, and FIG. (C) shows the voltage waveform across the charge storage capacitor 4, and (d) shows the voltage across the secondary coil 3b of the transformer 3.

FIG. 6 is a block diagram of a power supply device according to a modified embodiment of the present invention.

FIG. 7 is a timing diagram of output of control signals in the power supply device according to another embodiment of the present invention.

FIG. 8 is an output waveform diagram of a power supply device according to another embodiment of the present invention.

FIG. 9 is an operation principle diagram of a power supply device according to another embodiment of the present invention.

FIG. 10 is an operation principle diagram of a power supply device according to another embodiment of the present invention.

11 is an operation principle diagram of a power supply device in which the diode and the switch in FIG. 10 are integrally configured by an N-channel MOS-FET.

FIG. 12 is an operation principle diagram of a power supply device according to another embodiment of the present invention.

FIG. 13 is an operation principle diagram of a power supply device according to another embodiment of the present invention.

FIG. 14 is an operation principle diagram of a power supply device according to another embodiment of the present invention.

FIG. 15 is an operation principle diagram of a power supply device according to another embodiment of the present invention.

FIG. 16 is a circuit diagram of a conventional power supply device.

[Explanation of Codes] 1 power supply device 2 DC power supply 3 transformer 3a primary coil 3b secondary coil 4 charge storage capacitor 5 FET 6 FET 7 diode 8 diode bridge 9 smoothing capacitor 10 control unit 31 power supply device 32 diode bridge 41 switch 42 Switch 43 Coil 44 Coil 48 Diode 49 N-channel MOS-FET

Claims (16)

[Claims] 1. A capacitive element connectable to a DC power source, first switch means for forming a first closed loop circuit in which at least the capacitive element and the DC power source are connected in series, and at least the capacitance. A second switch means for forming a second closed-loop circuit including a series resonance circuit of an inductive element and an inductive element, and switch control means for alternately activating the first and second switch means. A circuit frequency based on the series resonance circuit is set to a frequency higher than a repetition frequency at which the switch control means operates the first switch means, and at least when the second switch is operated by the switch control means. In addition, the power supply device is characterized in that AC power based on resonance of the series resonance circuit is output from the second closed loop circuit. 2. An inductive element connectable to a direct current power source, first switch means for forming a first closed loop circuit in which at least the inductive element and the direct current power source are connected in series, and at least the inductive element. A second switch means for forming a second closed-loop circuit including a series resonant circuit of a capacitive element and a capacitive element, and the first switch means when connected in parallel to the second switch means. A current for blocking the inflow of the direct current of the direct current power source into the capacitive element and for moving the energy stored in the inductive element to the capacitive element when the first switch means is deactivated. Control means and switch control means for alternately activating the first and second switch means, wherein the circuit frequency based on the series resonant circuit is the switch control means. The AC power based on the resonance of the series resonant circuit is set to a frequency higher than a repetition frequency for operating the first switch means, and at least when the second switch is operated by the switch control means. A power supply device characterized by outputting from a closed loop circuit of 2. 3. The power supply device according to claim 2, wherein the second switch means and the current control means are integrally configured by an N-channel MOS-FET. 4. A series resonance circuit formed of at least an inductive element and a capacitive element and connectable to a DC power supply, and a first closed loop circuit in which the series resonance circuit and the DC power supply are connected in series. First switch means, second switch means for forming a second closed loop circuit including at least the series resonance circuit, and switch control means for alternately activating the first and second switch means. A circuit frequency based on the series resonant circuit is set to a frequency higher than a repetition frequency at which the switch control means operates the first switch means, and at least the second switch is operated by the switch control means. In this case, the AC power based on the resonance of the series resonance circuit is output from the second closed loop circuit. . 5. The inductive element is a primary coil of a transformer, and the second closed loop circuit outputs the AC power from a secondary coil of the transformer. The power supply device according to any one. 6. The power supply device according to claim 1, wherein the first closed loop circuit includes a current limiting unit that limits a current flowing from the DC power supply to a predetermined value. . 7. The power supply device according to claim 6, wherein the current limiting means is a choke coil. 8. The power supply device according to claim 1, further comprising rectifying / smoothing means for rectifying / smoothing the AC power to convert it into DC power. 9. A detection unit for detecting at least one of a voltage value and a current value of the AC power, wherein the switch control unit is configured to detect the first value based on a detection value of the detection unit.
2. The switch means of claim 1 is operated.
The power supply device according to any one of 1 to 8. 10. A detection means for detecting at least one of a voltage value and a current value of the DC power, wherein the switch control means operates the first switch means based on the detection value of the detection means. The power supply device according to claim 8, wherein 11. A plurality of sets of the first closed loop circuit formed by the first switch means and the second closed loop circuit formed by the second switch means according to claim 5, respectively. A closed loop circuit group, and switch control means for alternately activating the first and second switch means in the closed loop circuit group, wherein the secondary coil of each transformer of the closed loop circuit group has an annular connection and a star. Connected to any of the wire connections and configured to output AC power, the switch control means includes at least the second of each of the plurality of sets.
A power supply device characterized in that the operation timings of the switch means are shifted from each other. 12. The power supply device according to claim 11, further comprising a rectifying unit connected to each of the secondary coils connected to each other to rectify the AC power. 13. The switch control means shifts the operation timings of the second switch means to each other by a phase difference of a value obtained by dividing 2π by the number of the sets. Power supply. 14. A detection means for detecting at least one of a voltage value and a current value of the AC power, wherein the switch control means includes each first switch of the closed loop circuit group based on the detection value of the detection means. Power supply device according to any of claims 11 to 13, characterized in that it activates the means. 15. The power supply device according to claim 1, wherein the first closed loop circuit includes a backflow current blocking unit that blocks a backflow of current to the DC power supply. . 16. The switch control unit changes the duty ratio between the operating time of the first switch means and the operating time of the second switch means, as claimed in any one of claims 1 to 15. The power supply device according to.