JPH11285250A - Dc-to-dc converter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable high-precision stable power feeding by operating a DC-DC converter consisting of a plurality input power sources, shifting the phase of each operation timing of a plurality of switches for switching its input current on/off, and to prevent the generation of a simultaneous operation period. SOLUTION: In a DC-DC converter which uses a solar battery and a commercial power source as input power sources, a starting circuit 11 detects a reset signal of an inductor L and outputs an operating signal as a starting signal, and a first oscillator circuit 12 computes the overall operating period Ton, on the basis of a constant-voltage control signal generated by output voltage detection. Next, a switch operation control circuit 13 outputs an operation period signal Ton1 for a solar battery side switch based on a battery cutoff control signal and an optimum operating point tracking signal for the solar battery, and a signal Ton-Ton1 corresponding to an input power deficiency due to this. Here, a second oscillator circuit 14 outputs an operation period signal Ton2 for a commercial power source side switch whose phase of operation timing is shifted from that of the operation period signal Ton1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a single, stable power source obtained by adding a plurality of power supply sources, such as a commercial power source, a solar cell, a wind power generator, a geothermal power generator, a livestock battery, and the like. The present invention relates to a DC-DC converter capable of supplying power to an output.

[0002]

2. Description of the Related Art FIG. 9 shows an example of a DC-DC converter for supplying power from a plurality of DC input power supplies to a load, which is an object of the present invention. In FIG. 9, E1 and E2 are independent DC input power supplies, E1 is, for example, a solar cell, E2
DC power supplies converted from DC to DC power, D1, D2
Is a diode for blocking a reverse current to the DC input power supplies E1 and E2, S1 and S2 are switches for intermittently operating the currents of the DC input power supplies E1 and E2, and L is an inductor forming a magnetic circuit. N1 and N2 are inductors L
Is a primary winding whose mutual coupling is tightly wound, and N0 is a secondary winding for output whose coupling with N1 and N2 is similarly tightly wound. The winding value of each of these primary windings N1, N2 and secondary winding N0 corresponds to the voltage value of DC input power supplies E1, E2 and the output voltage value E0 supplied to load R, and the voltage per winding number is The number of turns is determined so as to be substantially equal. D0 is 2 induced in the secondary winding N0.
A diode C for rectifying the next AC voltage is a capacitor for smoothing the rectified pulsating current and supplying stable DC power to the load R. Further, in FIG.
I0 is an input current and an output current of the input power supplies E1 and E2, respectively.

Next, FIG. 10 shows an example of a conventional control circuit for controlling the operation of the converter circuit shown in FIG. 9, and its control operation is shown in FIG. 11 showing ON-OFF operation timings of switches S1 and S2. It will be described together with a time chart. In FIG. 10, reference numeral 1 denotes an oscillation circuit that outputs an operation period Ton of the switches S1 and S2, and a constant voltage control signal generated by detecting an output voltage E0 by a start signal using a reset signal of the inductor L and FIG. 11), the operation period Ton of FIG. 11B is obtained during one cycle Ts. 2 is switch S
The operation period Ton1 shown in FIG. 11C of the maximum power control signal obtained from the DC input power supply E1 of the solar cell is output as the operation signal of the switch S1 in the operation period Ton in the switch operation control circuits 1 and S2. In this case, Ton2 corresponding to the operation period Ton-Ton1 in FIG. 11D, which is generated as a difference, is output as the operation signal of the switch S2, and the operation period T in FIG.
on1 + Ton2 is output.

That is, the added operation period To of the two switches S1 and S2 in one cycle Ts shown in FIG.
n (Ton1 + Ton2) is determined by the sawtooth oscillator. Then, the switch S1 on the side of the DC input power supply E1 of the solar cell is operated for an optimum operation period Ton1 obtained by detecting a change in the output voltage value of the DC input power supply E1, and the operation period corresponding to the shortage of the load-side power. Ton2 (Ton-T
on1) is the switch S on the DC input power supply E2 side of the commercial power supply.
2, the output voltage E0 is stably supplied to the load side as an operation period Ton in which both are added. Such circuit configuration and ON-OFF of the switch
Because of the operation timing, the power output from the power supplies E1 and E2 is constantly transmitted to the output, and is practically used as an effective and efficient means in power supply.

[0005]

However, in the prior art, the switches S1 and S2 shown in FIG.
As can be understood from the operation timing, the switches S1 and S
2 is a continuous operation timing in which the two operation periods Ton1 and Ton2 are in contact without a rest period, so that a period during which the two switches S1 and S2 are simultaneously operated occurs, and the converter operation becomes unstable. There is a problem. The present invention has been developed to solve the above-mentioned problems.
DC that can operate the switches with different phases so that the simultaneous operation period does not occur, for the operation timings of the plurality of switches that intermittently operate the current of the DC-DC converter composed of a plurality of input power supplies
To provide a DC converter.

[0006]

SUMMARY OF THE INVENTION DC-DC according to the present invention
The converter includes a plurality of DC input power supplies, an output circuit having a smoothing circuit, an inductor or a transformer forming a magnetic circuit, and a plurality of DC input power supplies connected to the plurality of DC input power supplies and the output circuit and wound on the inductor or the transformer. And a switch for serially connecting the plurality of DC input power supplies and the windings connected to the plurality of DC input power supplies, respectively. After turning on the switches during the period so as to correspond to the optimum input power of the first DC input power supply of the plurality of DC input power supplies,
A DC-D which is configured to turn on a switch of a second DC input power supply of the plurality of DC input power supplies only during a period when the output voltage is reached, thereby supplying power to the output circuit.
In the C converter, the switch of the second DC input power supply is turned on after a required time has elapsed since the ON operation of the switch of the first DC input power supply was switched to the OFF operation during the one cycle. A DC-DC converter characterized by the above.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention is a DC-DC converter shown in FIG. 9, a control circuit shown in FIG. 1 for controlling the operation of the DC-DC converter, and FIGS. This will be described with reference to a circuit diagram, a timing diagram, a time chart, and the like. First, the basic configuration and operation of the present invention is based on the constant voltage control signal generated by detecting the output voltage E0 shown in FIG.
The entire operation period Ton of the two switches S1 and S2 during one cycle Ts is obtained, and as shown in the timing chart of FIG. 2, first, the optimum operation period Ton1 of the switch S1 and the remaining operation period Ton2 (Ton− Ton1) is delayed to be the operation period of the switch S2. When the output voltage E0 and the input currents I1 and I2 are derived in accordance with these conditions, the following equations (1), (2) and (3) are obtained.

[0008]

E0 = N0 × E1 × Ton1 / (N1 × (Ts−Ton1)) + N0 × E2 × Ton2 / (N2 × (Ts−Ton2)) (1) I1 = N0 × E0 × Ton1 / ( N1 × R × (Ts−Ton1)) (2) I2 = N0 × E0 × Ton2 / (N2 × R × (Ts−Ton2)) (3)

From these three equations, the output voltage E0 and the input currents I1 and I2 are equal to the operating periods Ton1 and Ton1 of the switches S1 and S2.
It is clear that control is possible with Ton2. A means for delaying the operation of the switch S2 is provided so that the phase shift operation is performed between the operation periods Ton1 and Ton2 of the switches S1 and S2, and each operation period is controlled to operate independently. is there. That is, an operation suspension period Toff1 is provided between the operation period Ton1 in FIG. 2B on the DC input power supply E1 side and the operation period Ton2 in FIG. 2C on the DC input power supply E2 side, and further, the operation period Ton2
An operation stop period Toff2 is provided between the DC input power supply E1 and the next operation period Ton1. The input current I1 flows from the DC input power supply E1 during the Ton1 period, and the next operation stop period. After Toff1, the input current I2 flows from the DC input power supply E2 during the Ton2 period.

Further, after an operation suspension period Toff2,
The operation of one cycle Ts in which the input current I1 flows during the Ton1 period from the DC input power supply E1 is repeated. At this time, the voltage from the DC input power supplies E1 and E2 is induced in the secondary winding N0 of the inductor L during the operation stop periods Toff1 and Toff2 by the magnetic flux excited by the primary currents due to the input currents I1 and I2. Is supplied with power.

[0011]

1, a starter circuit 11 detects a reset signal of an inductor L generated at the end of an operation stop period Toff1 and uses it as a starter signal. Reference numeral 12 denotes an entire operation period T based on a comparison between a constant voltage control signal generated by detecting the output voltage E0 in the first oscillation circuit and a sawtooth oscillation waveform.
I try to get on. Reference numeral 13 denotes a switch operation control circuit that detects the maximum power of the DC input power supply E1 from, for example, a solar cell from the entire operation period Ton, and outputs a control signal of the operation period Ton1 that is an optimal operation point signal thereof. 2 outputs the delayed operation period Ton2 of the DC input power supply E2 of the commercial power supply detected by the second oscillation circuit 14. The starting circuit 11 outputs an operation signal to the first oscillation circuit 12 or the second oscillation circuit 14 according to an oscillator selection signal from the switch operation control circuit 13.

Next, the operation of the entire control circuit of FIG.
This will be described with reference to the time chart of FIG. 4 and FIG. 3 showing a specific example of the second oscillation circuit 14. As described above, the comparison between the constant voltage control signal generated by detecting the output voltage E0 in the first oscillation circuit 12 and the sawtooth oscillation waveform in FIG.
The entire operation period To of FIG. 4B during the period Ts
n is obtained and output to the switch operation control circuit 13. The switch operation control circuit 13 responds to the shortage of the output power by the input of the operation period Ton1 of FIG. 4C which is the optimum operation point signal of the DC input power supply E1 from the solar cell, for example, as shown in FIG. The signal of Ton-Ton1 is output to the second oscillation circuit 14. As the second oscillation circuit 14, for example, a phase shift circuit for operating the switches S1 and S2 as shown in FIG. 3 is used.

That is, when the signal of Ton-Ton1 is input from the switch operation control circuit 13 to the base of the transistor Tr1, the transistor Tr1 is turned on and the transistor Tr1 is turned on.
During a period corresponding to Ton1, the capacitor C1 is charged with a constant current. After this charging is completed, an operation signal is input from the starting circuit 11 to the flip-flop 15, and the transistor T
r2 is set to the operating state, the capacitor C1 is set to the constant current discharging state, and Ton2 corresponding to Ton-Ton1 for turning on the switch S2 on the DC input power supply E2 side is output. FIG. 4 shows the state of charge and discharge of the capacitor C1.
FIG. 4E shows the waveform shown in FIG.
(F) shows the waveform, and in this case, Ton1 and T
A period corresponding to approximately Ton2 is vacant between on2 and on2, and the phase is shifted accordingly. The waveform shown in FIG. 4G is obtained by giving a reset signal of the inductor L to the starting circuit 11 as a starting signal.

Next, another embodiment of the second oscillation circuit 14 shown in FIG. 1 will be described with reference to FIG. FIG. 6 shows a counter using a digital circuit. In the up counter 21, the operation period Ton 1 of the DC input power supply E 1 of the solar cell is set to “H” by the action of a peripheral circuit including an inverter circuit 22. And the AND circuit 23
Of the clock signal counts up while the entire operation period Ton is "H" and the operation period Ton1 of the DC input power supply E1 is "L", and outputs the count-up data to the down counter 24. I do.
Further, the down-counter 24 converts the previous count-up data into a period in which the entire operation period Ton is “H” and the operation period Ton1 on the DC input power supply E1 side is “L” by the operation of the peripheral circuit including the AND circuit 25. set. Further, the output of the flip-flop 26 is set to the "H" level of the operation signal.
Is set to "H" during the period, and is simultaneously input to the AND circuit 27. Therefore, the countdown of the clock signal pulse is started, and when the data becomes zero, the "H" signal is output to the flip-flop 26 as a pulse. Then, the output of the flip-flop 26 is set to “L” to generate an operation period Ton2 for the switch S2 on the commercial power supply side.

In the control in this embodiment, for example, the output power is significantly reduced (so-called light load state).
When the operation period Ton is sufficient for the power of the DC input power supply E1 of the solar cell, that is, when the condition of Ton = Ton1 is satisfied, the operation of the switch S2 of the DC input power supply E2 of the commercial power supply is stopped, and the switch is stopped. Only S1 has one cycle Ts
It can be configured to operate efficiently and supply power twice a period. In such a case, to which of the two oscillator circuits 12 and 14 shown in FIG. 1 the operation signal is transmitted will be described with reference to the time chart of FIG. FIG.
5 shows a state where the power of the DC input power supply E1 is insufficient, and the right side of FIG. 5 shows a state where the power of the DC input power supply E1 is sufficient.

First, in the case of the left side of FIG. 5, when the operation period Ton1 on the side of the DC input power supply E1 ends, if the entire operation period Ton is in the "H" state, the switch operation control circuit 13 is activated. The circuit 11 includes a second oscillation circuit 14
When the operation period Ton is at the “L” state on the right side when the operation period Ton1 ends, the switch operation control circuit 13 selects the first oscillation circuit 14 as the activation circuit 11 Output signal. At night or when the amount of solar irradiation is extremely small and the amount of electric power of the solar cell is small, the battery disconnection control signal shown in FIG. 1 from the detecting means for detecting the output state of the solar cell is sent to the switch operation control circuit 13. Then, only the switch S2 on the commercial power supply side is operated twice within the period of one cycle Ts, so that power is efficiently supplied.

As another control configuration, a switch S1
Is fixed to an operation period obtained by detecting and tracking the optimum operation point of the solar cell, and a control operation period obtained by the output constant voltage control is provided as an operation period Ton2 of the switch S2. Is also good. Further, the present invention is not limited to a converter circuit using two DC input power supplies of a solar cell and a commercial power supply as in the above-described embodiment, but is not limited to three or more types as shown in FIG. It is also possible to apply to a converter circuit using an input power supply. Further, as shown in FIG. 8, the inductor L in the above-described embodiment is changed to the coupling by the transformer T,
The present invention can also be applied to a converter circuit in which an inductor L is set on the output side.

[0018]

Since the present invention is configured as described above, for example, when various types of natural energy power generation or commercial power supply whose power supply constantly fluctuates are used as an input power supply,
By operating these natural energy generation or commercial power supply operation periods with their phases shifted so that they operate independently, highly accurate and stable power supply is possible. This also promotes the use of a commercial power supply and natural energy power generation, or a plurality of types of natural energy power generation, and has the effect of reducing the power supplied to the commercial power supply.

[Brief description of the drawings]

FIG. 1 is a block circuit diagram showing one embodiment of a control circuit of a DC-DC converter of the present invention.

FIG. 2 shows ON-O of a switch according to an embodiment of the present invention.
It is a timing chart of FF operation.

FIG. 3 is a circuit diagram showing an embodiment of a main part of a control circuit of the DC-DC converter of the present invention.

FIG. 4 is a time chart of a control circuit according to an embodiment of the present invention.

FIG. 5 is a time chart for explaining a means for detecting the necessity of using a multi-input power supply according to the present invention.

FIG. 6 is a circuit diagram of another embodiment of the main part of the control circuit of the DC-DC converter of the present invention.

FIG. 7 is a circuit diagram of an embodiment of a DC-DC converter of a multi-input power supply to which the present invention is applied.

FIG. 8: DC-D using the present invention as a transformer coupling
It is a circuit diagram of one embodiment of a C converter.

FIG. 9 is a basic circuit diagram of a DC-DC converter using two types of DC input power supplies to which the present invention is applied.

FIG. 10 is a block circuit diagram showing one embodiment of a control circuit of a conventional DC-DC converter.

FIG. 11 is a time chart showing an example of a conventional control circuit.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Oscillator circuit 2, 13 Switch operation control circuit 11 Starter circuit 12 First oscillator circuit 14 Second oscillator circuit 15, 26 Flip-flop circuit 21 Up counter 22 Inverter circuit 23, 25, 27 AND circuit 24 Down counter E1 Solar cell DC input power supply E2 DC input power supply by commercial power supply EM input power supply E0 Output voltage D1, D2, D0, DM, DR, D01, D02 Diode S1, S2, SM switch L Inductor C, C1 Capacitor R Load resistance N1, N2 NM, NR L or T primary winding N0 L or T secondary winding I1 E1 current I2 E2 current IM EM current I0 Current flowing to load R Tr1, Tr2 Transistor T Transformer

Claims (3)

[Claims] A plurality of DC input power supplies; an output circuit having a smoothing circuit; an inductor or transformer forming a magnetic circuit; and a plurality of DC input power supplies connected to the plurality of DC input power supplies and the output circuit, respectively. A winding connected to the plurality of DC input power supplies and a switch configured to serially connect the plurality of windings connected to the plurality of DC input power supplies, and detecting an output voltage of the output circuit. After turning on the switches during one cycle so as to correspond to the optimum input power of the first DC input power supply of the plurality of DC input power supplies, A DC-DC converter in which a switch of a second DC input power supply of the power supply is turned on only during a period of reaching the output voltage to supply power to the output circuit. After a required time has elapsed since the on-operation of the switch of the first DC input power supply was switched to the off-operation during the one cycle, the on-operation of the switch of the second DC input power supply is performed. A DC-DC converter characterized in that: 2. A capacitor charging / discharging circuit that turns on the switch of the second DC input power supply which is operated after a required time has elapsed since the ON operation of the switch of the first DC input power supply is switched to the OFF operation. 2. The DC-DC converter according to claim 1, wherein the DC-DC converter is operated by using a delay. 3. An on / off operation of a switch of the second DC input power supply, which is operated after a required time has elapsed since the on operation of the switch of the first DC input power supply is switched to an off operation, is added / subtracted by a counter. 2. The DC-DC converter according to claim 1, wherein the DC-DC converter is configured to perform a delay operation using a circuit.