JPH10117474A - Switching capacitor power source - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent spike current and noise and convert lifting pressure by connecting voltage averaging capacitors in parallel to any of selected ones of a plurality of capacitors connected in series. SOLUTION: By connecting input voltage, in an input selection circuit SELi, to both ends of capacitors whose quantity is (p) connected in series inside capacitors C1 ...Cn whose quantity is (n), and averaging charges of the capacitors C1 ...Cn whose quantity is (n) with a voltage averaging capacitors Ce, the voltage of n/p times the input voltage is generated. When the voltage between both the ends of capacitors whose quantity is (q), connected in series among the capacitors C1 ...Cn whose quantity is (n) is taken out through an output selection circuit SELo, the voltage becomes (n/p)×(q/n)=q/p times the input voltage. By selecting the quantity (p) of the capacitors which applies the input voltage and the quantity (q) of the capacitors which take out the output voltage, it is possible to attain lifting pressure.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a switched capacitor power supply, and more particularly, to a switched capacitor (SC) power supply capable of stepping up and down.

[0002]

2. Description of the Related Art A DC-DC converter,
DC-AC converter, AC-DC converter, AC-
Power supplies such as AC converters have been proposed. Since these power supplies do not use magnetic components such as transformers and coils,
It can be made into an IC and has features of small size, light weight, and high efficiency.

[0003]

In the series-parallel switching type SC power supply proposed so far, there is a moment when the input / output current becomes "0" every time the series-parallel switching is performed, and at the beginning of each state. A large spike-like current flows, increasing noise. In addition, the conversion ratio of voltage step-up / step-down is n times, or 1 / n
Fixed to double.

An object of the present invention is to provide a switched capacitor power supply capable of changing the step-up / step-down conversion ratio.

Another object of the present invention is to provide a switched capacitor power supply capable of reducing noise.

[0006]

According to one aspect of the present invention, there are provided n capacitors connected in series, the capacitors comprising n + 1 voltage nodes at both ends and an interconnection point. An input selection circuit for applying an input voltage to the voltage nodes across the p capacitors connected in series among the n capacitors and charging the p capacitors; and an input selection circuit for charging the p capacitors. An output selection circuit for deriving an output voltage from the voltage nodes at both ends of the q capacitors connected in series, discharging the q capacitors, a voltage averaging capacitor, and the voltage averaging capacitor And a selection circuit for voltage averaging that can be connected in parallel to any of the n capacitors.

[0007] In this specification, the capacitors connected in series include not only a plurality of capacitors but also a single capacitor.

An input voltage is applied to p capacitors out of n equal capacitors, an output voltage is derived from q capacitors out of n capacitors, and the p capacitors and q capacitors are derived. By sequentially connecting a capacitor for voltage averaging to a capacitor included in any of the capacitors in parallel, a boosted / decreased output voltage can be provided.

When the input voltage is applied to p capacitors out of n capacitors and a voltage averaging capacitor is connected in parallel to each of the n capacitors, the n capacitors are charged uniformly. be able to. The voltage across the n capacitors is n / p times the input voltage. n
A divided voltage is formed at the interconnection point of the capacitors. Deriving the output voltage from both ends of the q capacitors out of the n capacitors gives (n / q) · (q /
n) = q / p voltage conversion is performed. It is not necessary to perform the voltage averaging operation on a capacitor that does not charge or discharge.

According to another aspect of the present invention, a step of applying an input voltage to p series-connected capacitors of the n series-connected capacitors to charge them, Deriving an output voltage from both ends of the q capacitors connected in series, discharging the q capacitors, and averaging the voltages of the capacitors included in at least one of the p and q capacitors. And a averaging step.

[0011]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1A shows a switched capacitor circuit according to an embodiment of the present invention. The switched capacitor circuit SC0 includes n capacitors C1, C connected in series.
2,... Cn. Wirings L0, L are connected to both ends a0, an of the n capacitors C1,... Cn connected in series.
n are connected. The interconnection points a1,..., an-1 of the n capacitors C1,.
... Ln-1 are connected.

The wirings L0,... Ln are connected to input wirings Li0,. ... Φin constitute an input selection circuit SELi.

The wirings L0,... Ln are output side wirings L.
... Lon and switches Φo0,. Φon constitute an output selection circuit SELo.

The voltage averaging capacitor Ce is connected to the capacitors C1,... Via a pair of switches Φe1,.
Any of Cn can be connected in parallel. The switches Φe1,... Φen are connected to a voltage averaging selection circuit SELe.
Is configured.

FIG. 1B shows a capacitor C for voltage averaging.
, and the relationship between the capacitors C1,... Cn. The voltage averaging capacitor Ce can be connected in parallel to any of the capacitors C1,... Cn.

The capacitances of the capacitors C1,... Cn are assumed to be equal. The capacitance of the voltage averaging capacitor Ce is not particularly limited, but is set to a value equivalent to, for example, C1,... Cn = C.

For example, if the voltage averaging capacitor Ce is connected in parallel to the capacitors C1,... Cn sequentially, all the capacitors C1,... Cn are charged uniformly and have an equal terminal voltage.

For example, when the input voltage is set to n capacitors C
1,... Cn connected to both ends of p series-connected capacitors and averaging the electric charges of the n capacitors C1,. , Cn generate a voltage n / p times the input voltage.

In this state, n capacitors C
When the voltage between both ends of q capacitors connected in series among 1,... Cn is taken out via the output selection circuit SELo, the voltage is (n / p) · (q / n) = q of the input voltage.
/ P times. As described above, by selecting the number p of the series-connected capacitors for applying the input voltage and the number q of the series-connected capacitors for extracting the output voltage, the voltage can be stepped up and down.

If the ground potential is set to one of the intermediate wirings L1,... Ln-1, polarity conversion can be performed. For example, the wiring L2 is set to the ground potential and the input side wiring L
A power supply voltage of negative polarity is connected to i2 and Li0, the output-side wiring Lo2 is used as an output-side ground wiring, and the output-side wiring Lo3,.
If any of the on is the output side power supply wiring, a positive output voltage can be formed from a negative input voltage.

Similarly, a negative input voltage can be formed from a positive input voltage. Also, a bipolar output voltage can be formed from a power supply voltage of one polarity.
An output voltage of one polarity or both polarities can be formed from the input voltage of both polarities. Further, a switch Φo0,
By turning on a plurality of .PHI.on, a multi-output power supply can be formed.

If the connection of the input voltage and the connection of the output voltage are fixed, the input current and the output current flow continuously, and noise can be reduced.

The switch Φ of the output selection circuit SELo
... Φon, a pseudo AC waveform can be formed by sequentially converting a pair of switches that are turned on. Switches Φi0,... Φ of the input selection circuit SELi
It is also possible to charge the capacitor with an AC waveform by sequentially switching in.

In FIG. 1A, n connected in series
The input side switches Φi0,... Are connected to wirings connected to both ends of the capacitors C1,.
And Φo0,. When the ground potential wiring is fixed, the input-side switch Φ connected to the ground wiring
i0 and the output side switch Φo0 can be omitted.

FIG. 1C shows a simplified configuration when the ground wiring is fixed. 1A is different from FIG. 1A in that the lowermost wiring L0 in the figure is fixed to the ground wiring.
The input switch Φi0 and the output switch Φo0 in (A) are omitted, and the wiring L0 is directly connected to the input wiring Li0 and the output wiring Lo0.

The input terminals of the input selection circuit SELi are commonly connected and connected to an input voltage terminal Vin. The output side wirings of the output selection circuit SELo are commonly connected, and are connected to the output terminal Vout. The ground potential of the input voltage is connected to the input terminal Gin, and the high-potential side of the input voltage is connected to the input voltage terminal Vin. On the output side, the ground terminal is Gout, and the output terminal Vout
Derives the high-side output voltage from

In this configuration, the p capacitors to which the input voltage is applied are C1,... Cp, and the q capacitors from which the output voltage is derived are C1,.

FIGS. 2A to 2D show examples of an input voltage supply circuit connected to the switched capacitor circuit SC1, and an output voltage utilization circuit receiving an output voltage from the switched capacitor circuit SC1.

FIG. 2A shows a case where the DC voltage V1 serves as an input voltage supply source of the switched capacitor circuit SC1. DC power supply V1 to switched capacitor circuit SC1
Is supplied with a current i1.

FIG. 2B shows a configuration in which the rectifier circuit REC is connected to the input voltage terminal of the switched capacitor circuit SC1, and the AC power supply Vac is connected to the input terminal of the rectifier circuit. The AC voltage supplied from the AC power supply Vac is rectified by the rectifier circuit REC and is supplied as a unipolar voltage to the switched capacitor circuit SC1.

The rectifier circuit REC may be a full-wave rectifier circuit or a half-wave rectifier circuit. When the rectifier circuit REC is a full-wave rectifier circuit, the output voltage of the rectifier circuit REC has a waveform that increases and decreases at twice the frequency of the power supply Vac.

In this case, if the ON state of the switch of the input selection circuit SELi shown in FIG. 1C is fixed, the charging voltage of the capacitor increases or decreases. In order to stabilize the state of charge of the capacitor, the selected switch of the input selection circuit SELi is turned on only when the output voltage of the rectifier circuit REC becomes, for example, 90% or more of the peak voltage, and the input is switched during other periods. All switches of the selection circuit SELi may be turned off.

The switches of the input selection circuit SELi may be sequentially switched according to the output voltage of the rectifier circuit REC.

FIG. 2C shows a configuration in which the load _RL is directly connected between the output terminals of the switched capacitor circuit SC1. In this case, a unipolar output current i2 flows from the output terminal Vout toward the terminal Gout.

FIG. 2D shows a switched capacitor circuit.
A load R is connected to the output terminal Vout of SC1. _LIs the polarity conversion circuit P
The configuration connected via E is shown. The polarity conversion circuit PE
Switch Φ_NAre simultaneously turned on / off, and the switch Φ_P
Are simultaneously turned off / on.

When the pair of switches Φ _P is on, the output current i2 flows through the load _RL from left to right. When the pair of switches Φ _N is on, the output current i2 flows through the load _RL from right to left. In this case, the switches of the output selection circuit SELo shown in FIG. 1C can be sequentially switched to create a pseudo sine waveform.

FIGS. 3A and 3B show configurations for a step-down power supply and a step-up power supply, respectively.

In FIG. 3A, 4 connected in series
The input voltage Vi is applied across the two capacitors C1,... C4, and the output voltage Vo is derived from the ground potential and, for example, the upper voltage node a1 of the capacitor C1.
The voltage averaging capacitor and the voltage averaging selection circuit are not shown. Since the input voltage Vi is voltage-divided by the capacitors C1,... C4, C1 = C2
= C3 = C4, but also C1 ≠ C2 ≠ C3 ≠ C4
In this case, the voltage Vo at both ends of C1 is と of the input voltage by the voltage averaging capacitor and the voltage averaging selection circuit.

In this case, the capacitor C1 is charged and discharged, while the capacitors C2, C3, C4
Is only charged.

In this case, in order to make the terminal voltages of the capacitors more uniform, the voltage averaging capacitors Ce are alternately connected to the charged and discharged capacitors C1 and the only discharged capacitors C2, C3 and C4. Is preferred.
For example, the partner connected in parallel with the voltage averaging capacitor may be a sequence of C1-C2-C1-C3-C1-C4.

When the output voltage Vo is derived from the voltage node a2, which is the interconnection point between the capacitors C2 and C3,
Capacitors to be charged and discharged are C1 and C2, and capacitors only to be charged are C3 and C4. In this case,
A capacitor connected to the voltage averaging capacitor Ce is, for example, C1-C3-C2-C4-C1-C4-C
A sequence such as 2-C3 may be selected.

When output voltage Vo is derived from voltage node a3, which is an interconnection point between capacitors C3 and C4, the sequence of the capacitors connected to voltage averaging capacitor Ce is, for example, C4-C1-C4- C2-
What is necessary is just to select like C4-C3.

As described above, when the voltage drop is performed,
By alternately connecting the capacitor to be charged only and the capacitor to be charged and discharged, the voltage of each capacitor can be more efficiently averaged.

Note that among the capacitors connected in series,
If there is a capacitor that is not charged by the input voltage and is not discharged by the output voltage, the voltage averaging capacitor Ce need not be connected to this capacitor.

When the voltage node to which the input voltage is connected is the same as the voltage node from which the output voltage is derived,
Since each capacitor does not charge or discharge in particular, the operation of sequentially connecting the voltage averaging capacitors to the capacitors may not be performed.

However, since it may be considered that the voltage averaging of each capacitor is not sufficient, it is better to connect the voltage averaging capacitors sequentially to each capacitor and perform the voltage averaging in the following state. The initial peak current flowing at different output voltage nodes can be reduced.

FIG. 3B shows an example of the configuration when boosting is performed. The input voltage Vi is supplied to a voltage node a2 which is an interconnection point between the capacitors C2 and C3, and the output voltage Vo is derived from a voltage node a4 which is an upper terminal of the capacitor C4. In this case, it is preferable that the capacitor for voltage averaging is alternately connected to capacitors C1 and C2 to be charged and discharged and capacitors C3 and C4 to be discharged only. For example, the sequence of capacitors to which the capacitor for voltage averaging is connected is represented by C1-C3-C2-C4-C1-C4.
What is necessary is just to make it like -C2-C3.

When the output voltage Vo is derived from the voltage node a3 which is an interconnection point between the capacitors C3 and C4,
The only capacitor discharged is C3. In this case, the sequence of the capacitors connected to the voltage averaging capacitor Ce may be, for example, C3-C1-C3-C2. In this case, since the capacitor C4 is neither charged nor discharged, it is excluded from the connection partner of the voltage averaging capacitor.

As described above, by providing switches on the input side and the output side of each voltage dividing node of the capacitors connected in series, a switched capacitor power supply capable of stepping up and down is provided.

Although the case where the capacitors connected in series have the same capacitance has been described, even if the capacitances are different, the voltages of all the capacitors are averaged by the operation of the voltage averaging capacitor and the voltage averaging selection circuit. Therefore, capacitors having different capacitances can be connected. However, in this case, it is preferable to use at least a plurality of capacitors having the same capacitance and to use one voltage averaging capacitor for the capacitors having the same capacitance.

For example, among the capacitors connected in series, the capacitor on the low voltage side is used as the first capacitance,
The capacitance of the capacitor on the high voltage side is defined as a second capacitance larger than that. Separate voltage averaging capacitors and voltage averaging selection circuits are provided on the low voltage side and the high voltage side, respectively. With this configuration, when the input or output is at a low voltage, the voltage division can be performed finely.

The present invention has been described in connection with the preferred embodiments.
The present invention is not limited to these. For example,
It will be apparent to those skilled in the art that various modifications, improvements, combinations, and the like can be made.

[0054]

As described above, according to the present invention,
A buck-boost switched capacitor power supply is provided.

If the input voltage is continuously applied to the p capacitors connected in series, noise can be reduced.

[Brief description of the drawings]

FIG. 1 is a circuit diagram illustrating a switched capacitor circuit according to an embodiment of the present invention.

FIG. 2 is a circuit diagram showing a configuration example of a circuit connected to an input side and an output side of the switched capacitor circuit shown in FIG.

FIG. 3 is a circuit diagram showing an example of step-down and step-up.

[Explanation of symbols]

SC (SC0, SC1) Switched capacitor circuit SELi Input selection circuit SELo Output selection circuit SELe Voltage averaging selection circuit C1,... Cn Charging / discharging capacitor Ce Voltage averaging capacitor Φ Switch _RL load

Claims (8)

[Claims] 1. n capacitors connected in series, wherein n capacitors forming n + 1 voltage nodes at both ends and an interconnection point, and n capacitors connected in series among the n capacitors an input selection circuit for applying an input voltage to voltage nodes across the p capacitors and charging the p capacitors; and an input selection circuit for connecting the q capacitors in series among the n capacitors. An output selection circuit for deriving an output voltage from a voltage node and discharging the q capacitors, a voltage averaging capacitor, and connecting the voltage averaging capacitor to any of the n capacitors in parallel And a selection circuit for voltage averaging. 2. One of the two voltage nodes at both ends of the n capacitors is connected to a common potential, and the input selection circuit changes the input voltage, which is not the common potential, from the voltage node of the common potential to p. 2. The switched capacitor power supply according to claim 1, wherein the voltage is applied to a voltage node, and the output selection circuit derives a voltage that is not the common potential from the qth voltage node from the common node. 3. The rectifier circuit according to claim 1, further comprising a rectifier circuit for inputting an AC voltage and supplying a rectified voltage to the input selection circuit. 3. The switched capacitor power supply according to claim 2, wherein the voltage is applied to the p-th voltage node. 4. A polarity inverting circuit for receiving the output voltage, inverting the polarity, and supplying the inverted voltage to a load.
Or the switched capacitor power supply according to 2. 5. The voltage averaging selection circuit alternately connects the voltage averaging capacitor to a capacitor that performs only one of charging and discharging and a capacitor that performs both charging and discharging. A switched capacitor power supply according to any one of claims 1 to 4. 6. A step of applying an input voltage to p series-connected capacitors among the n series-connected capacitors to charge the same, and q series-connected q-series capacitors among the n capacitors. Deriving an output voltage from both ends of the capacitor and discharging the q capacitors, and averaging the voltages of the capacitors included in at least one of the p and q capacitors. Voltage conversion method. 7. The voltage conversion according to claim 6, wherein said averaging step includes a step of sequentially connecting a voltage averaging capacitor in parallel to said capacitor performing at least one of said charging and discharging, and averaging the voltage of said capacitor. Method. 8. The averaging process according to claim 7, wherein the voltage averaging capacitor is alternately connected in parallel to a capacitor performing only one of the charging and discharging and a capacitor performing both the charging and discharging. Voltage conversion method.