JPH05336734A - Dc-dc converter - Google Patents

Abstract

PURPOSE:To invert the input voltage and boost it so as to get inverse output voltage by so constituting this DC-DC converter as to connect one end of a series circuit, where the second switch of each unit circuit is connected in series, to load through an output switch. CONSTITUTION:Switches S11 and S12 are turned on. Next, switches S21 and S22 and a switch S13 are turned on after the tuning-on of the switches S11 and S12. Hereby, a capacitor C2 is charged with the voltage of 2E where the interterminal voltage E of a capacitor C1 is loaded on the DC voltage E of a DC power source A. Next, when switches S13, S23, S33,..., Sn-1, 3, and Sn are turned on, the capacitor Cn of output is charged by the voltage -(2<n-2>-1) E of the sum to the interterminal voltage of the capacitors C1, C2,..., and Cn-1, and the interterminal voltage of the capacitor Cn for output at this time becomes -(2<n-2>-1) E. By repeating this, inverse output voltage, where the DC voltage is being input voltage is boosted, can be gotten.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a DC-DC converter for converting a DC voltage into a desired DC voltage, and more specifically to a step-up DC-DC converter capable of obtaining an inverted output voltage and an inverted output voltage. The present invention relates to a step-down DC-DC converter.

[0002]

2. Description of the Related Art Due to the miniaturization of electronic devices such as communication devices,
There is a demand for downsizing, weight reduction, and high efficiency of DC-DC converters that convert a DC voltage into a desired DC voltage. In addition, there is an increasing demand for a wide variety of DC power supplies such as a polarity reversal type high voltage output power supply. Especially switched-capacitor DC-DC
Since the converter does not use a transformer, it is suitable for downsizing and weight reduction.

FIG. 14 shows a conventional switched capacitor system.
2 shows a step-up DC-DC converter of. DC power
Switch S to DC power supply A that outputs pressure E₁₁And capacity
Ta C ₁And switch S₁₃And a series circuit with is connected,
Switch S₁₁And capacitor C ₁The series circuit with
Chi S₁₂Are connected in parallel to form the first unit circuit
There is. Capacitor C₁And switch S₁₃In series circuit with
Is the switch S_{twenty one}And capacitor C₂And switch S_{twenty three}With
The series circuit is connected in parallel, and the switch S_{twenty one}And capacity
Shita C₂In the series circuit with the switch S_{twenty two}Are connected in parallel
The second unit circuit. Capacitor C₂
And switch S_{twenty three}In the series circuit with
(Not shown) are connected in series in the same manner as described above, namely,
Capacitor C ₂And switch S_{twenty three}In the series circuit with, for example,
Switch S_n-1,1And capacitor C_{n- 1}And switch S
_n-1,3And the series circuit of is connected in parallel, and the switch S
_n-1,1And capacitor C_n-1In the series circuit with the switch S
_n-1,2Are connected in parallel. Capacitor C_n-1And Sui
Touch S_n-1,3In the series circuit with the switch S_nAnd for output
Capacitor C_nThe series circuits of are connected in parallel and output
Capacitor C_nLoad R_LAre connected in parallel.
Capacitor C₁, C₂… C_n-1Is a charge transfer capacitor
Has become.

Next, the operation of this DC-DC converter is switched.
15 timing chart and operation timing chart
And Fig. 16 showing the equivalent circuit for the switching states of
I will explain to you. First, switch S₁₁, S₁₃Turn on
Then, the state 1 shown in FIG.₁Is straight
Charged by the DC voltage E of the current source A, and the capacitor C ₁
The terminal voltage of is E. Then switch S₁₁, S₁₃The
After switching off, switch S_{twenty one}, S_{twenty three}, S₁₂Turn on
And state 2 shown in Fig. 16 (b), the DC voltage of DC power supply A
E to capacitor C₁The voltage E between the terminals of the
Capacitor C with DC voltage of E₂Is charged and capacitor
C₂The voltage between the terminals is 2E. Where the switch
S₁₂, S_{twenty two}, S₃₂(Not shown) ... S_n-1,1, S_n-1,3To
In the state n-1 shown in Fig. 16 (c) when turned on, the capacity is
Shita C₁, C₂, C₃… C_n-1The voltage between the terminals is E,
2E, 4E ... 2^n-2It becomes E. And switch S₁₂,
S_{twenty two}, S₃₂... S_n-1,2, S_nWhen turned on, the screen shown in Fig. 16 (d)
As shown in the state n, the DC voltage E of the DC power supply A is capacitated.
Ta C₁, C₂, C₃… C_n-1The voltage across each terminal of
DC voltage 2^n-1Output capacitor C by E_nIs charged
Output capacitor C_nThe voltage between terminals is 2^n-1With E
Become.

Then, the above-mentioned operation is repeated by setting the state 1 to the state n as one cycle T. Thereby,
According to the DC-DC converter shown in FIG. 14, an output voltage that is 2 ^n-1 times the DC voltage E of the DC power supply A that is the input voltage can be obtained. When changing the switching state of the switch, a pause period is provided after the switch that is on is turned off, and the switch that should be in the next state is turned on so that the charge stored in the capacitor is not discharged. There is. When the number of switching states of the switch is n, an n-phase clock is used as a clock for turning the switch on and off.

FIG. 17 shows a conventional switched capacitor system.
1 shows a step-down DC-DC converter. Output key
Capacitor C_nAnd load R_LSwitch S in the parallel circuit₁₁When
Capacitor C ₁And switch S₁₃Connected in series circuit with
And switch S₁₁And capacitor C ₁In series circuit with
Is switch S₁₂Are connected in parallel. Capacitor C₁
And switch S₁₃In the series circuit with the switch S_{twenty one}And
Pasita C₂And switch S_{twenty three}And the series circuit with is connected in parallel
And switch S_{twenty one}And capacitor C₂In series circuit with
Is switch S_{twenty two}Are connected in parallel. Where the capacity
Shita C₁And switch S₁₁, S₁₂, S₁₃No. 1 composed of
The unit circuit of the eye is the switch S₁₁And capacitor C₁When
Of the capacitor C₂And switch S_{twenty one}, S_{twenty two}, S
_{twenty three}The switch S of the second unit circuit composed of_{twenty one}And S_{twenty two}
Is connected to the connection part with. Below, similarly from the second
The same unit circuits are sequentially connected to (n-1)
Unit circuits up to the th are constructed. Configure like this
And the switch S in the (n-1) th unit circuit
_n-1,3And capacitor C_n-1And switch S_n-1,1Series of
Although not shown, the n-th unit circuit
Pasita C_n-2And switch S_n-2,3Series circuits are connected in parallel
Has been continued. Also, the capacitor C_n-1And switch S
_n-1,1In the series circuit with the switch S_n-1,2Are connected in parallel
Has been. Further, for the DC power supply A that outputs the DC voltage E,
Switch S_nAnd capacitor C_n-1And switch S_n-1,3When
Connected in series circuit. Capacitor C₁, C₂，
… C_n-1Is a charge transfer capacitor.

Next, the operation of the DC-DC converter will be described with reference to the timing chart of FIG. 18 showing the operation timing of the switch and FIG. 19 showing the equivalent circuit for the switching state of the switch. Here the capacitors _{C 1, C 2 ... C n} -1, the voltage across the terminals of C _n at steady state in the DC-DC converter of FIG. 17, and _{E 1, E 2 ... E n} -1, E n. First, when the switches S ₁₁ and S ₁₃ are turned on, the state 1 shown in FIG.
The charged capacitor C _n is the inter-terminal voltage E ₁ of the capacitor C ₁ becomes, the terminal voltage E ₁ of the capacitor C ₁ and the terminal voltage E _n of the output capacitor C _n is equal.

[0008] That is, the voltage between the terminals E ₁ of the capacitor C ₁
Becomes E _n . Next, after turning off the switches S ₁₁ and S ₁₃ , only turning on the switches S ₁₂ , S ₂₁ and S ₂₃ ,
19 ready 2 (b), the output capacitor C _n by the voltage of the sum of the terminal voltage E ₁ and the terminal voltage E ₂ of the capacitor C ₂ of the capacitor C ₁ is charged, the capacitor C
₁ and the terminal voltage of the series circuit of the capacitor C _2, and the terminal voltage E _n of the capacitor C _n is equal. That is,
Terminal voltage E ₂ of the capacitor C ₂ becomes 2E _n. After that, the switch S _n-2,2 (not shown) following the switch S ₂₂
While turning on each of the switches up to, switch S ₂₁
And a switch S _n-1,1 following the switch S ₃₁ (not shown)
16 and by sequentially turning on the switches up to S _n-1,3 .
The state 2 shown in FIG. 16B to the state n-1 shown in FIG. 16C are sequentially formed. Therefore, the switches S ₁₂ , S ₂₂ ... S
_{When only n-2,2} , S _n-1,1 and S _n-1,3 are turned on, FIG.
The state becomes n-1 shown in (c), and the capacitor C _n-1 ...
C _3, C _2, the output capacitor C _n by the voltage of the sum of the voltage across the terminals of C ₁ is charged, the voltage between the terminals E _n-1 of the capacitor C _n-1 becomes ^{2 _n-2} E ^n.

Next, the switches S ₁₂ , S ₂₂ , S ₃₂ ...
When only S _n-1,2 , S _n are turned on, the state n shown in FIG.
_n-1 ... C _3, to charge the C _2, C _1, the DC voltage E of the DC power supply A is 2 _^n-1 E ^n. In this way, the capacitor C
_n and capacitors C ₁ , C ₂ , C ₃ ... C _n-1 are connected in series, and the voltage across each terminal increases in the order of capacitors C ₁ , C ₂ , C ₃ ... C _{n- 1} , The lowest voltage between terminals. Then, from such state 1 to state n, 1
The operation described above is repeated as a cycle T. Thereby the figure
According to the DC-DC converter shown in 17, the capacitor C _n
Further, the output voltage reduced by 1 / (2 ^n-1 ) times the DC voltage E of the DC power supply A can be obtained.

When changing the switching state of the switch, a rest period is provided after the switch that is on is turned off, and the switch that should be in the next state is turned on so that the charge stored in the capacitor is not discharged. I am trying. When the number of switching states of the switch is set to n, an n-phase clock is used as a clock for turning the switch on and off.

[0011]

As described above, in the conventional step-up DC-DC converter, when the number of switching states of the switch is n, the DC voltage E, which is the input voltage, is multiplied by 2 ^{n-1 to} obtain 2 ^n. An output voltage of ^-1 E is obtained, and a large boost ratio is obtained. However, when a new capacitor is charged by superposing the inter-terminal voltage of the capacitor charged to the DC voltage of the DC power supply, the positive electrode of the DC power supply and the electrode of the capacitor charged with negative charge are connected. However, there is a problem that the output capacitor is always supplied with the same positive voltage as the polarity of the DC power source through the output switch, and an inverted output voltage obtained by inverting the polarity of the DC power source cannot be obtained.

On the other hand, in the conventional step-down DC-DC converter, when the number of switching states of the switch is n, the DC voltage E, which is the input voltage, is multiplied by 1 / (2 ^n-1 ) to obtain 2 ^1-n E. An output voltage is obtained and a large step-down ratio is obtained. However, when the capacitor is charged by the DC voltage of the DC power source, the capacitor is connected in series and charged, and the output capacitor is connected in parallel to the charged capacitor to charge the output capacitor. There is a problem that a positive voltage that is the same as the polarity of the DC power source is always applied, and an inverted output voltage that is the polarity of the DC power source cannot be obtained. In view of such a problem, the present invention is a step-up type that can obtain an inverted output voltage.
An object is to provide a DC-DC converter and a step-down DC-DC converter.

[0013]

In a DC-DC converter according to a first invention, a first switch, a capacitor, and a second switch are connected in series, and the capacitor and the second switch are connected.
A plurality of unit circuits in which a third switch is connected in parallel to a series circuit with a switch are connected in parallel to be connected to a DC power supply, and the second switch of each unit circuit is connected in series. It is characterized in that one end of the connected series circuit is configured to be connected to a load via an output switch.

The DC-DC converter according to the second invention is the first invention.
A switch, a capacitor, and a second switch are connected in series, and a plurality of unit circuits each of which is formed by connecting a third switch in parallel to a series circuit of the capacitor and the second switch are connected in parallel to form a load. The second switch of each unit circuit is connected in series, and one end of the series circuit is connected to the DC power supply via the input switch.

[0015]

In the first invention, when the first switch and the second switch of the first unit circuit are turned on, the DC power supply charges the capacitor of the unit circuit. At that time, a negative charge is stored in the electrode of the capacitor on the side of the second switch connection. When the first switch and the second switch of the first unit circuit are turned off, the first switch and the second switch of the second unit circuit are turned on, and the third switch of the first unit circuit is turned on, the second switch The capacitor of the unit circuit is charged with a voltage obtained by superposing the inter-terminal voltage of the capacitor, which has been previously charged with the DC voltage of the DC power supply. Negative charge is stored in the electrode of the second unit circuit on the second switch connection side of the capacitor. Similarly, the capacitor of each unit circuit is charged to the last and the inter-terminal voltage gradually increases. As a result, the input voltage can be inverted and boosted, and an inverted output voltage can be obtained.

In the second invention, when the first switch and the second switch of the first unit circuit are turned on, the voltage between the terminals of the capacitor of the unit circuit is supplied to the load. The first switch and the second switch of the first unit circuit are turned off, and the third switch of the first unit circuit and the first switch of the second unit circuit are turned on.
When the switch and the second switch are turned on, the sum of the voltages between the terminals of the capacitor of the first unit circuit and the capacitor of the second unit circuit is supplied to the load. Similarly, the voltage of the sum of the voltages between the terminals of the capacitors of each unit circuit is supplied to the load until the last. The voltage between the terminals of each capacitor is the first, second ... n-1 with respect to the voltage between the terminals of the load.
The capacitors of the second unit circuit become higher in order. When the capacitor of each unit circuit is charged in series by the DC power source, negative charge is stored in the electrode of the capacitor of the (n-1) th unit circuit on the side of the third switch connection. As a result, the input voltage can be inverted and reduced, and an inverted output voltage can be obtained.

[0017]

The present invention will be described in detail below with reference to the drawings showing the embodiments thereof.
I will describe. FIG. 1 is a main part of a DC-DC converter according to the first invention.
It is a block diagram which shows a structure. The negative electrode is grounded,
The first switch is the DC power supply A that outputs the DC voltage E.
Switch S₁₁, S_{twenty one}... S_n-1,1And capacitor C₁, C₂
… C_n-1And the second switch, switch S₁₂, S_{twenty two}... S
_n-1,2Series circuit with and capacitor C₁, C₂… C _n-1
And switch S₁₂, S_{twenty two}... S_n-1,2Connected in parallel to the series circuit with
Switch S, which is the continued third switch₁₃, S_{twenty three}... S
_n-1,3Unit circuit U consisting of₁, U₂… U_n-1Is connected
ing. Unit circuit U_n-1Capacitor C at_n-1And
Itch S_n-1,2Output switch S is connected to_nThrough
Output capacitor C_nIs connected to one end of
Road U₁Switch S at₁₂And S₁₃Connection with is for output
Capacitor C_nIs connected to the other end and is grounded. output
Capacitor C_nLoad R_LAre connected. Cat
Pasita C₁, C₂… C_n-1Is a charge transfer capacitor
It

Next, the operation of the DC-DC converter configured as described above will be described with reference to the timing chart of FIG. 2 showing the operation timing of the switch and FIG. 3 showing the equivalent circuit for the switch switching state. First, the switches S ₁₁ and S
_{When 12} is turned on, the state 1 shown in FIG. 3 (a) is reached, the capacitor C ₁ is charged by the DC voltage E of the DC power supply A, and the terminal voltage of the capacitor C ₁ becomes E.

Next, the switch S₁₁, S₁₂After turning off
Switch S_{twenty one}, S_{twenty two}And switch S ₁₃When turned on
Is the state 2 shown in Fig. 3 (b), and the DC voltage of the DC power supply A is
Capacitor C on E₁2E with voltage E between terminals stacked
Voltage of capacitor C₂Is charged. And capacity
Ta C₂The voltage between the terminals is 2E. Where switch S
₁₃, S_{twenty three}, S₃₃(Not shown) ... S_n-1,1, S_n-1,2only
When is turned on, the state becomes n-1 shown in Fig. 3 (c),
Capacitor C₁, C₂, C₃(Not shown) ... C _n-1Edge of
The inter-child voltages are E, 2E, 4E ... 2, respectively.^n-2It becomes E.

Next, when the switches S ₁₃ , S ₂₃ , S ₃₃ (not shown) ... S _n-1,3 , S _n are turned on, the state n shown in FIG. ₁ , C ₂ , C ₃ ... C _n-1
The output capacitor C _n is charged by the sum voltage − (2 ⁿ⁻² −1) E of the terminals of the output capacitor C _n , and the terminal voltage of the output capacitor C _n at this time is − (2 ⁿ⁻² −1). It becomes E. Then, the above-described operation is repeated with the state 1 to the state n as one cycle T. As a result, an inverted output voltage obtained by boosting the DC voltage E, which is the input voltage, to − (2 ⁿ⁻² −1) E is obtained.

In FIG. 4, the number of switch switching states n is four.
It is a block diagram which shows the principal part structure of a DC-DC converter.
The negative electrode is grounded, and a DC power supply A that outputs a DC voltage E is connected to a first switch S ₁ , S ₄ , S ₇ and capacitors C ₁ , C ₂ , C ₃ and a second switch S ₂ , S ₅ , A _third circuit connected in parallel with a series circuit of S ₈ and a series circuit of capacitors C ₁ , C ₂ , C ₃ and second switches S ₂ , S ₅ , S ₈ .
A unit circuit U ₁ including switches S ₃ , S ₆ and S ₉ ,
U ₂ and U ₃ are connected. The connection between the capacitor C ₃ and the second switch S ₈ is connected to one end of the output capacitor C ₀ via the output switch S ₁₀ , and the other end is the connection between the second switch S ₂ and the third switch S _3. Is connected to and grounded. A load R _L is connected to the output capacitor C ₀ .

Next, the operation of this DC-DC converter will be described.
Timing chart of FIG. 5 showing the operation timing of the switch
And FIG. 6 showing an equivalent circuit for the switching state of the switch.
More will be described. Switch S₁, S₂If you turn on
The state 1 shown in FIG.
Shita C₁Is charged, the capacitor C₁Terminal voltage is E
Becomes Then switch S₁, S₂After turning off the
Itch S₃, S_Four, S _FiveFigure 6 when only turning on
The state 2 shown in (b) is reached, and the DC voltage E of the DC power supply A changes to
Capacitor C₁The voltage of 2E, which is obtained by stacking the voltage E between the terminals of
And capacitor C₂Is charged, the capacitor C₂Terminal
The voltage between them becomes 2E.

Next, the switch S₃, S₆, S₇, S₈only
When is turned on, the state becomes 3 as shown in Fig. 6 (c), and the DC
DC voltage E of power supply A, capacitor C₁Terminal voltage E
And capacitor C₂Terminal voltage of 2E and 4
Capacitor C at voltage of E₃Is charged and the capacitor C₃
Terminal voltage becomes 4E. Then switch S₃, S₆, S
₉, S_TenWhen only one is turned on, state 4 shown in Fig. 6 (d)
And the capacitor C ₁Terminal voltage E and capacitor C
₂Terminal voltage of 2E and capacitor C₃Terminal voltage 4E
Output voltage C by the sum of voltage 7E₀Charge
It And the output capacitor C₀The voltage between terminals is 7E
Becomes, capacitor C₃Output switch S _TenConnection side is negative
Since the load is stored, the output capacitor C₀Between terminals
The pressure is -7E.

By repeating the above-described operation with the period 1 to the state 4 as one cycle T, an inverted output voltage of -7E obtained by inverting and boosting the DC voltage E which is the input voltage is obtained, and is applied to the load R _L. Given. It was confirmed by experiments that when the four capacitors of this DC-DC converter were each set to 10 μF and the DC voltage of the DC power supply A was set to 12.5 V, an inverted output voltage of -87.5 V was obtained. In this way, it is possible to obtain a DC-DC converter that can obtain an inverted output voltage with approximately the same number of constituent parts as the conventional DC-DC converter. Moreover, MOSFET can be used for the switch.

FIG. 7 is designed to stabilize the output voltage.
It is a block diagram of a control circuit of a DC-DC converter. The DC power supply A is connected to the DC-DC converter unit 20 composed of the plurality of unit circuits described above, and the output capacitor C _n.
Are connected. The load R _L is applied to the output capacitor C _n.
Are connected in parallel. The voltage between the terminals of the output capacitor C _n , that is, the output voltage, is applied to one input terminal of the error amplifier 21, and the reference voltage V _R is applied to the other input terminal of the error amplifier 21. The output of the error amplifier 21 is given to a modulator 22 that performs pulse width, frequency or on-resistance modulation.

The modulation outputs φ ₁ ... φ _n of the modulator 22 are individually applied to the switches as signals for controlling the duty of switches (not shown) in the DC-DC converter section 20. In this DC-DC converter, when the output voltage supplied to the load _RL changes, the output of the error amplifier 21 changes. Then, the modulation signals φ ₁ ... φ _n output from the modulator 22 change according to the output of the error amplifier 21. As a result, the duty of the switch for switching the connection of the charge transfer capacitor of the unit circuit changes, and the voltage between the terminals of the capacitor changes according to the change in the output voltage. That is, the DC-DC converter section
The output voltage of 20 will be fed back to the switch via modulator 22 to stabilize the output voltage.

FIG. 8 shows a DC-DC converter according to the second invention.
It is a block diagram which shows the principal part structure. One end is grounded
Output capacitor C_nLoad R connected in parallel with_LIn the first
1 switch, switch S₁₁, S_{twenty one}... S_n-1,1And capacity
Shita C₁, C₂… C_n-1And the second switch, switch S
₁₂, S_{twenty two}... S_n-1,2Series circuit with and capacitor C₁，
C₂… C_n-1And switch S₁₂, S_{twenty two}... S_n-1,2In series with
A switch S, which is a third switch connected in parallel with the circuit.₁₃，
S_{twenty three}... S_n-1,3Unit circuit U consisting of₁, U₂… U_n-1But
It is connected. Unit circuit U_n-1Capacitor C at
_n-1And switch S_n-1,2Input switch S is connected to_n
Connected to a DC power supply A that outputs a DC voltage E via
The negative electrode of the DC power supply A is grounded. Capacitor
C₁, C ₂… C_n-1Is a charge transfer capacitor.

Next, the operation of the DC-DC converter configured as described above will be described with reference to the timing chart of FIG. 9 showing the operation timing of the switch and FIG. 10 showing the equivalent circuit for the switch switching state. In the steady state of the DC-DC converter in FIG. 8, capacitors C ₁ , C ₂ ... C _n-1 ,
The voltages across the terminals of C _n are E ₁ , E ₂ ... E _n-1 , E _n , respectively. First, when the switches S ₁₁ and S ₁₂ are turned on, FIG.
ready 1 (a), the terminal voltage E ₁ of the capacitor C ₁ output capacitor C _n is charged by the voltage across the terminals E ₁ of the capacitor C ₁ becomes E _n. Then switch S
_11, when turning on the switch S _21, S ₂₂ and the switch S ₁₃ after the S ₁₂ is turned off becomes state 2 shown in FIG. 10 (b), the inter-terminal voltage E ₁ of the capacitor C ₁ and capacitor C ₂
The output capacitor C _n is charged with a voltage that is the sum of the inter-terminal voltage E _{2 of} The terminal voltage E ₂ of the capacitor C ₂ becomes 2E _n.

Here, when only the switches S ₁₃ , S ₂₃ , S ₃₃ (not shown) ... S _n-1,1 and S _n-1,2 are turned on, FIG.
The state becomes n−1 shown in (c), and the capacitors C ₁ , C ₂ ,
C ₃ (not shown) ... The output capacitor C _n is charged with a voltage that is the sum of the voltages across the terminals of C _n-1 , and the capacitors C ₁ ,
The voltage between the terminals of C ₂ , C ₃ ... C _n-1 is E _n , 2E _n , ... 2
the _^n-2 E ^n.

Next, the switch S₁₃, S_{twenty three}, S₃₃…
S_n-1,3, S_nFig. 10 (d) shows when only the power is turned on.
In the state n, the voltage E between the terminals of the DC power supply A is
Ta C₁, C₂, C₃… C_n-1Voltage of the sum of the voltage between terminals of 2
^n-1E_nBecomes Capacitor C₁, C ₂, C₃… C_n-1
The voltage across each terminal of₁, C₂, C₃… C_n-1
Becomes higher in order. Therefore, the DC voltage of the DC power supply A
If E, output capacitor C_nThe voltage between the terminals is
1 / (2^n-1) It becomes E and the pressure is lowered. And such a state
The above operation is repeated with 1 to state n as one cycle T.
return. Also, the capacitor C_n-1Switch S_n-1,3Connection
Negative charges are stored in the side electrode. This makes the input voltage
The barrel DC voltage E is -1 / (2^n-1-1) Inverted output with voltage reduced to E
The output voltage is obtained.

FIG. 11 is a block diagram showing a main configuration of a step-down DC-DC converter in which the number of switch switching states n is four. The load R _L connected in parallel with the output capacitor C ₄ whose one electrode is grounded is connected to the first switches S ₁ and S ₁ .
₄ , S ₇ and capacitors C ₁ , C ₂ , C ₃ and the second switch S ₂ , S ₅ , S ₈ in series circuit, and capacitor C ₁ ,
Unit circuits U ₁ , U ₂ , U ₃ composed of third switches S ₃ , S ₆ , S ₉ connected in parallel to a series circuit of C ₂ , C ₃ and second switches S ₂ , S ₅ , S ₈ are connected. Has been done. The connection between the capacitor C ₃ and the second switch S ₈ is connected to the positive electrode of the DC power supply A that outputs the DC voltage E via the input switch S ₁₀ . The negative electrode of the DC power supply A is grounded.

Next, the operation of the DC-DC converter will be described with reference to the timing chart of FIG. 12 showing the operation timing of the switch and FIG. 13 showing the equivalent circuit for the switching state of the switch. Now, let us say that the voltages across the terminals of the capacitors C ₁ , C ₂ , C ₃ , C ₄ in the steady state of the DC-DC converter in FIG. 11 are E ₁ , E ₂ , E ₃ , E ₄ .

Switch S₁, S₂When turned on, Fig. 13
In the state 1 shown in (a), the capacitor C₁Voltage between terminals
E₁Capacitor C_FourIs charged and the capacitor C₁
Terminal voltage and capacitor C_FourTerminal voltage E_FourEtc.
I want to That is, the capacitor C ₁Terminal voltage E₁Is
Capacitor C_FourTerminal voltage E_FourIs equal to Next
Touch S₁, S₂Switch off, switch S₃，
S_Four, S_FiveWhen only one is turned on, the state shown in Fig. 13 (b)
2, the capacitor C₁Terminal voltage E₁And capacity
Ta C₂Terminal voltage E₂Capacitor by the sum of voltage
C_FourIs charged and the capacitor C₁And capacitor C₂With
Voltage between terminals of series circuit and capacitor C_FourVoltage between terminals
E_FourAnd are equal.

That is, the capacitor C₂Terminal voltage E₂Is
2E_Fourbecome. Then switch S₃, S₆, S₇, S₈of
When only the power is turned on, the state 3 shown in Fig. 13 (c) is reached and the capacity is
Shita C₁, C₂, C₃Depending on the sum of the voltages between the terminals of
Capacitor C_FourIs charged and the capacitor C₃Between terminals
Pressure E₃Is 4E_Fourbecome. Then switch S₃, S₆，
S ₉, S_TenTurning only on turns it into the state 4 shown in Fig. 13 (d).
Then, the DC voltage E of the DC power supply A causes the capacitor C₁，
C₂, C₃To charge. And the DC voltage E is 7E_FourTona
It

In this way, the capacitor C₁, C₂, C
₃The voltage across each terminal of ₁, C₂, C₃Order of
Becomes higher and capacitor C₁Has the lowest voltage across the terminals. Well
When charging with the DC power supply A, the capacitor C₃Output of
Itch S₇Since a negative charge is stored on the connection side, a DC power supply
Capacitor C for the polarity of A_FourVoltage between terminals, that is, DC-
The output voltage of the DC converter is inverted. Therefore, direct current
When the power source is E, the capacitor C_FourThe voltage between the terminals is
-It becomes 1 / 7E.

By repeating the above-described operation with the period 1 to the state 4 as one cycle T, the inverted output voltage of -1 / 7E obtained by inverting and stepping down the DC voltage E which is the input voltage is obtained. Given to the load R _L. In addition, this
If the four capacitors of the DC-DC converter are 10 μF each and the DC voltage of the DC power supply A is 87.5 V, -12.5
It has been confirmed experimentally that an inverted output voltage of V can be obtained.

In this way, it is possible to obtain a step-down DC-DC converter that can obtain an inverted output voltage with the same number of components as the conventional DC-DC converter. Moreover, MOSFET can be used for the switch. In addition, step-down DC-DC
To stabilize the converter output voltage, use a boost DC
By configuring as shown in FIG. 7 as in the case of the -DC converter, the output voltage can be stabilized similarly to the step-up DC-DC converter.

[0038]

As described above in detail, according to the present invention, a step-up DC-DC converter and a step-down DC-DC converter, which can obtain an inverted output voltage, are provided by using the same number of circuit components as the conventional DC-DC converter. It has an excellent effect of providing a DC converter.

[Brief description of drawings]

FIG. 1 is a block diagram showing a main configuration of a step-up DC-DC converter according to a first invention.

FIG. 2 is a timing chart showing operation timings of switches in the DC-DC converter shown in FIG.

FIG. 3 is an equivalent circuit diagram of the DC-DC converter with respect to a switching state of a switch.

FIG. 4 is a block diagram showing a main configuration of another embodiment of the step-up DC-DC converter according to the first invention.

5 is a timing chart showing operation timings of switches in the DC-DC converter shown in FIG.

FIG. 6 is an equivalent circuit diagram of the DC-DC converter with respect to the switching state of the switch.

FIG. 7 is a schematic block diagram of a DC-DC converter designed to stabilize the output voltage.

FIG. 8 is a block diagram showing a main configuration of a step-down DC-DC converter according to a second invention.

9 is a timing chart showing operation timings of switches in the DC-DC converter shown in FIG.

FIG. 10 is an equivalent circuit diagram of the DC-DC converter for the switching state of the switch.

FIG. 11 is a block diagram showing a main part configuration of another embodiment of the step-down DC-DC converter according to the second invention.

12 is a timing chart showing operation timings of switches in the DC-DC converter shown in FIG.

FIG. 13 is an equivalent circuit diagram of the DC-DC converter with respect to the switching state of the switch.

FIG. 14 is a block diagram showing a main configuration of a conventional step-up DC-DC converter.

15 is a timing chart showing operation timings of switches in the DC-DC converter shown in FIG.

FIG. 16 is an equivalent circuit diagram of the DC-DC converter for the switching states of the switches.

FIG. 17 is a block diagram showing a main configuration of a conventional step-down DC-DC converter.

18 is a timing chart showing operation timings of switches in the DC-DC converter shown in FIG.

FIG. 19 is an equivalent circuit diagram of the DC-DC converter for the switching states of the switches.

[Explanation of symbols]

A DC power supplies S ₁₁ , S _{12 to} S _n-1 , S ₁ , S _{2 to} S ₈
Switch S _n , S ₁₀ Output (input) switch C ₁ , C _{2 to} C _n-1 Capacitor C _n , C ₀ Output capacitor U ₁ , U ₂ , U _n-1 Unit circuit _RL Load 20 DC-DC converter Part 21 Error amplifier 22 Modulator

Claims (2)

[Claims] 1. A plurality of unit circuits each comprising a first switch, a capacitor, and a second switch connected in series, and a third switch connected in parallel to a series circuit of the capacitor and the second switch. It is configured to be connected in parallel to a set and connected to a DC power source, and one end of a series circuit in which the second switch of each unit circuit is connected in series is configured to be connected to a load via an output switch. A DC-DC converter characterized in that there is. 2. A plurality of unit circuits each including a first switch, a capacitor, and a second switch connected in series, and a third switch connected in parallel to a series circuit of the capacitor and the second switch. It is configured to be connected in parallel to a load and to be connected to a load. One end of a series circuit in which the second switch of each unit circuit is connected in series is configured to be connected to a DC power source via an input switch. A DC-DC converter characterized in that there is.