JPH07163144A - Multi-input dc-dc converter - Google Patents

Abstract

PURPOSE:To provide a stable multi-input DC-DC converter by eliminating the Rouse Hurwitz instability. CONSTITUTION:The multi-input DC-DC converter comprises an inductor L forming a closed magnetic circuit, windings N1, N2, N0 wound around the inductor L depending on a plurality of DC input power supplies E1, E2 and an output R while being coupled tightly each other to equalize the voltage per the number of turns, PWM switches S1, S2 connected in series with the windings N1, N2 corresponding to the input power supplies E1, H2 in order to turn the input power supplies E1, E2 ON/OFF, and pulse width control means corresponding to the input power supplies El, E2 and turning the input power supplies E1, E2 ON/OFF. The pulse width control means 6 is turned ON synchronously with turn OFF operation of a prestage pulse width means 4.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multi-input DC-DC converter device for adding a plurality of outputs from a solar cell and a wind power generator to obtain a single stable output.

[0002]

2. Description of the Related Art Attempts have been made to combine solar cells and complementary power sources such as wind power generators to obtain stable electric power that is not affected by the weather. In such a case, the configuration of the conventional 2-input DC-DC converter is shown in FIG.
What is shown by the block circuit of (b) is known.

In FIG. 3 (a), E1 and E2 are
For example, it represents an independent power source by a solar cell and a wind power generator and voltages of these power sources. These power supplies E1 and E2 are supplied with currents I1 and I2 by switches S1 and S2 for disconnecting current.
Is turned on and off to form a PWM (pulse width modulation) waveform, which is input to the input / output conversion circuit 41. At the output of the input / output conversion circuit 41, a DC output voltage E0 corresponding to the input PWM waveform is obtained. This output voltage E0 and one power supply E1
Voltage E1 is sent to the control circuit 42, and the control circuit 42 controls the control timing outputs Ton1 and Ton based on these voltages.
2 is output and the switches S1 and S2 for interrupting current are turned ON-
It is turned off to generate a required PWM waveform and control so that the output voltage E0 is always constant.

The control circuit 42, as shown in FIG.
Pulse width modulation signals P1 and P2 for determining the pulse width of PWM based on the voltage E1 of the power source E1 and the output voltage E0
Control timing outputs Ton1 and Ton based on the pulse width modulation signals P1 and P2 and the voltage converters 43 and 44 that generate
A sawtooth wave generator 45 for generating 2 and comparators 46 and 47 for comparing the sawtooth wave waveform voltage W of the sawtooth wave generator 45 with the pulse width modulation signals P1 and P2 are provided. In the comparators 46 and 47, the waveform voltage W of the sawtooth wave is compared with the pulse width modulation signals P1 and P2, and the control timing outputs Ton1 and Ton2 for driving the switches S1 and S2 are output. The control timing outputs Ton1 and Ton2 are the ON times of the current interrupting switches S1 and S2, respectively.

FIG. 4 shows the conventional 2-input DC-type circuit shown in FIG.
It is the operation timing of the control circuit 42 of the DC converter. In FIG. 7A, W represents the waveform of a sawtooth wave, Ts represents its cycle, and t represents the passage of time. The instantaneous waveform value of the sawtooth wave W is compared with the pulse width modulation signals P1 and P2 in the comparators 46 and 47, and as shown in FIG.
Control timing output T
on1. Further, as shown in FIG. 7C, the time t from the time when the sawtooth wave W becomes equal to the pulse width modulation signal P1 to the time when it becomes equal to the pulse width modulation signal P2 is the control timing output Ton2. In this way, the control timing outputs Ton1 and Ton2 are set so that they do not overlap, and as a whole circuit, as shown in FIG. 6 (d), it becomes an ON time when Ton1 + Ton2 are integrated, and both switches S1 and S2 are turned on. Toff is the time when neither of them is on, which is the off time of the circuit.

[0006]

As described above, in the conventional circuit configuration, the ON time of PWM is divided only by one sawtooth wave W, so that, for example, the power source voltage E1 is slightly changed due to noise or the like. When the pulse width modulation signal P1 also changes by + ΔP1 due to the existence of the minute + ΔE1, the control timing output Ton1 changes to Ton1 + ΔTon1 and, as a result,
The control timing output Ton2 appears in the form of being narrowed by -ΔTon1. Therefore, the width of the stability condition obtained from the transfer function of the circuit becomes narrow, and Rous-Hulwitz instability easily occurs.

The present invention has been made to solve this problem, and its object is to provide a stable multi-input DC-DC converter device by eliminating the instability of Rous-Hulwitz.

[0008]

SUMMARY OF THE INVENTION Multi-input DC-of the present invention
The DC converter device is provided by winding around an inductor or a transformer forming a magnetic circuit and the inductor or transformer corresponding to each of a plurality of DC input power supplies and output circuits, and the mutual coupling is tight and the number of turns per winding is large. A plurality of windings wound so that the voltages are equal,
A plurality of DC input power supplies and a plurality of switches that are connected in series to the windings corresponding to these input power supplies and perform ON-OFF of each DC input power supply to perform pulse width modulation, and the voltage of the DC input power supplies corresponding to these switches. Pulse width control means for ON / OFF control according to the above, and multi-input DC for rectifying the voltage induced in the winding of the output circuit and outputting it as an output by ON / OFF controlling the switches in a predetermined order.
In the DC converter device, the pulse width control means is provided corresponding to each DC input power source, and each pulse width control means operates in synchronization with the OFF operation of the pulse width control means in the preceding stage.
N is working.

[0009]

With this configuration, even if the PWM pulse width of the pulse width control means of the preceding stage fluctuates due to the fluctuation of the input power source of the preceding stage, for example, the pulse width of the pulse width control means of the next stage is changed. First, the Rous Hulwitz instability can be eliminated.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. 1A and 1B are circuit diagrams of an embodiment of the present invention. In FIG. 1 (a), E1 and E2
Represents an independent DC input power source, for example, a solar cell and a wind power generator, and voltages of these power sources. These power sources E1 and E2 are diodes D1 and
It is connected to the primary windings N1 and N2 of the inductor L forming a magnetic circuit through D2 and the switches S1 and S2 for interrupting the current. The inductor L has a primary winding N1,
The secondary winding N0 is wound together with N2 so as to be closely coupled to each other, and the winding numbers of these windings N1, N2 and N0 are supplied to the voltages E1 and E2 and the load R of the input power sources E1 and E2. The number of turns is determined so that the voltage per number of turns becomes equal to the output voltage E0. The secondary winding N0 supplies the secondary AC voltage induced in the secondary winding N0 to the capacitor C and the load R for smoothing the pulsating current through the rectifying diode D0, and causes the load current I0 to flow through the load R. I am trying. The voltage E1 of one power source, for example, the power source E1
And the output voltage E0 of the load R is sent to the control circuit 1, and the control circuit 1 outputs the control timing output Ton for driving the switches S1 and S2 for interrupting the current based on these voltages.
1 and Ton2 are output, and these control timing outputs Ton1
, Ton2 control the switches S1 and S2 for current interruption to interrupt the input current I1 from the power source E1 flowing through the primary winding N1 and the input current I2 from the power source E2 flowing through the primary winding N2 to output the load R. The voltage is controlled to be constant. Note that r1, r2 and r0 are internal resistances of the respective circuits, and the switches S1 and S2 may be mechanical ones or switches made of a semiconductor or the like.

In the control circuit 1 of this embodiment, as shown in FIG. 1B, pulse width modulation signals P1 and P2 for determining the PWM pulse width based on the voltage E1 of the power source E1 and the output voltage E0. Voltage converters 2 and 3, a sawtooth wave generator 4 serving as pulse width control means for determining the control timing output Ton1 of the power source E1 based on the pulse width modulation signal P1, and the sawtooth wave generator 4 and cycle. And the waveform has the same slope, and the phase relationship is the control timing output Ton which is the output of the sawtooth wave generator 4 via the trigger circuit 5.
A sawtooth wave generator 6 which is controlled by 1 and determines the control timing output Ton2 is provided. Further, the waveform voltage W1 of the sawtooth wave generator 4 and the pulse width modulation signal P1
And a comparator 8 for comparing the waveform voltage W2 of the sawtooth wave generator 6 and the pulse width modulated signal P2. The comparator 7 is provided with a sawtooth wave voltage W1.
Is compared with the pulse width modulation signal P1 to output a control timing output Ton1 for driving the switch S1. Further, the comparator 8 compares the instantaneous value of the sawtooth wave voltage W2 with the pulse width modulation signal P2, and the switch S2
The control timing output Ton2 for driving the motor is output. Then, the sawtooth wave generator 6 controls the falling position of the sawtooth wave W2 by the control timing output Ton1 via the trigger circuit 5 to determine the phase thereof. Control timing output Ton1, Ton
2 turns on the switches S1 and S2 for interrupting the current, respectively.
It is the ON time to make N.

FIG. 2 shows the operation timing of the control circuit 1 of the 2-input DC-DC converter of this embodiment. In the figure, W1 and W2 are sawtooth wave generators 4 and 6, respectively.
Represents the sawtooth waveform of Ts, and Ts is both sawtooth waveforms W1 and W
2, the period t indicates the passage of time. Sawtooth wave W
The waveform instantaneous value of 1 is the pulse width modulation signal P in the comparator 7.
1 is compared, and the time t from the start of the operation of the sawtooth wave W1 to the time when it becomes equal to the pulse width modulation signal P1 becomes the control timing output Ton1, as shown in FIG.

The trigger circuit 5 controls the operating position of the sawtooth wave generator 6 by detecting the fall of the control timing output Ton1 shown in FIG. As a result of this control, the sawtooth waveform W2 of the sawtooth wave generator 6 has a phase in which the operation starts at the fall of the control timing output Ton1, as shown in FIG. Then, as shown in FIG. 9D, the time t from the operation start time of the sawtooth wave W2 to the time point when it becomes equal to the pulse width modulation signal P2 becomes the control timing output Ton2. The whole circuit is usually the same (e)
As shown in, it is the ON time when Ton1 + Ton2 are integrated.

Control timing output Ton2 of this embodiment
Is determined only by the sawtooth waveform W2 of the sawtooth wave generator 6 as described above, so that, for example, there is a minute variation + ΔE1 due to noise or the like in the power supply voltage E1, and therefore the pulse width modulation signal P1 is P1 + ΔP1. And the control timing output Ton1 changes to Ton1 + ΔTon1
The waveform W2 of the sawtooth wave generator 4 is only shifted in phase by + ΔTon1 and the width of the control timing Ton2 is not changed. Therefore, the instability factor of Rous-Hulwitz is suppressed, and the converter of the embodiment operates stably.

The present invention is not limited to the above embodiment, but can be carried out within the scope of the invention. For example, in the above embodiment, the sawtooth wave generator is used as the pulse width control means, but any means that can determine the ON time of the PWM pulse width in accordance with the voltage value can be used as the pulse width control means. it can.

[0016]

According to the present invention, it is possible to provide a multi-input DC-DC converter device which operates stably, by eliminating the instability of Rous-Hulwitz even if the input power supply fluctuates.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing a configuration of a 2-input DC-DC converter according to an embodiment of the present invention.

FIG. 2 is a timing chart explaining the operation of the embodiment.

FIG. 3 is a circuit diagram showing a configuration of a conventional 2-input DC-DC converter.

FIG. 4 is a timing chart illustrating the operation of a conventional 2-input DC-DC converter.

[Explanation of symbols]

 1 control circuit 2,3 voltage converter 4,6 sawtooth wave generator 5 trigger circuit 7,8 comparator E1, E2 input power supply and its voltage E0 output voltage D1, D2, D0 diode S1, S2 switch N1, N2 of L Primary winding N0 L secondary winding I1 Input power supply E1 current I2 Input power supply E2 current I0 Output current flowing into load R1 Input power supply E1 circuit internal resistance r2 Input power supply E2 circuit internal resistance r0 Output circuit Internal resistance of Ton1, Ton2 control timing output

Claims (1)

[Claims] 1. An inductor or a transformer forming a magnetic circuit, and a plurality of DC input power supplies and output circuits are wound around the inductor or transformer in correspondence with each other. Pulse width modulation by connecting in series with a plurality of windings wound so that the voltages are equal to each other, a plurality of DC input power supplies, and windings corresponding to these input power supplies and turning each DC input power supply ON-OFF. And a pulse width control means for ON-OFF controlling these switches according to the voltage of the corresponding DC input power source, and the switches are turned on in a predetermined order.
In a multi-input DC-DC converter device which rectifies a voltage induced in a winding of an output circuit by N-OFF control and takes out as an output, the pulse width control means is provided corresponding to each DC input power source, A multi-input DC-DC converter device in which each pulse width control means is turned on in synchronization with the off operation of the preceding pulse width control means.