JPH07123703A - Converter circuit - Google Patents

Abstract

PURPOSE:To provide a converter circuit which has a voltage boost and drop functions and, at the same time, does not cause large losses. CONSTITUTION:A converter circuit is provided with an electric power supplying means 10, first electric power accumulating means 11 which accumulates electromagnetic energy, and second electric power accumulating means 9 which accumulates electric changes. The means 10 is connected in series with the means 11 through a first switching means 8 and the means 11 is connected in series with the means 9 through a second switching means 7. The converter circuit is controlled so that the electric power accumulated in the means 11 from the means 10 can be used for changing the means 9 by controlling the opening/closing of the switching means 8 and 7 and the electric power accumulated in the means 9 is discharged to the means 11, and then, the discharged power can be regenerated to the electric power supplying means 10.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a conversion circuit, and more particularly to a conversion circuit which performs voltage conversion having a wide dynamic range characteristic.

[0002]

2. Description of the Related Art In order to drive a load such as a piezoelectric element by applying a predetermined drive voltage, it is necessary to adjust the drive voltage that sets the operating condition of the load. As such an adjustment drive voltage generation circuit, a voltage conversion circuit as shown in FIG. 8 is used.

In FIG. 8, a DC power supply 20, an inductor 23, a diode 24, and a capacitor 22 are connected in series, and a switch 21 is provided between the DC power supply 20 and the connection point between the inductor 23 and the diode 24. Has been. First, switch 21 is closed and inductor 2
A coil current is passed through the switch 3, and after a lapse of a predetermined time, the switch 21
Is opened, a coil current is supplied to the capacitor 22 via the diode 24 to charge it, and the boosted voltage is obtained as the output voltage by increasing the charging voltage.

[0004]

As described above, in the conventional voltage conversion circuit, the circuit composed of the capacitor 22 and the inductor 23 allows the output of a larger absolute value from the DC power supply voltage E as the input voltage. Although it is a circuit having a boosting function for obtaining a voltage, it has a boosting function by charging the capacitor 22 but cannot discharge the capacitor charge, so that it cannot achieve the step-down function.

In order to discharge the electric charge of the capacitor 22, it suffices to connect a resistor in parallel to the capacitor 22, but the resistors connected in parallel always consume power, so that the power efficiency of the entire system circuit is lowered. There is.

Therefore, an object of the present invention is to provide a conversion circuit which has a step-up / step-down function and has little loss.

[0007]

In order to solve the above-mentioned problems, the conversion circuit according to the present invention comprises a power supply means, a first power storage means for storing electromagnetic energy, and a second power storage means for storing electric charge. And a first switching means for exchanging energy between the power supply means and the first power storage means, and between the first power storage means and the second power storage means. And a second switching means for exchanging energy, and a control means for controlling opening and closing of the first and second switching means. The control means supplies the electric power stored in the first power storage means from the power supply means via the first switching means to the second power storage means via the second switching means. Control to charge,
The power charged in the second power storage means is discharged to the first power storage means via the second switching means, and the discharged power is supplied to the power supply means via the first switching means. The voltage of the second electric power storage means is changed by performing at least one of the regenerative control. A conversion circuit according to another aspect of the present invention includes a first loop circuit in which an input power supply circuit, an inductive element, and a first opening / closing means are connected in series,
A second circuit in which a circuit having a circuit including a second switching means and a capacitive element or a battery is connected in series to the inductive element.
A loop circuit for controlling the opening / closing of the first opening / closing means and the second opening / closing means to allow bidirectional power supply between the input power supply circuit and the circuit including the capacitive element or the battery. It is configured to give and receive, change the voltage of the circuit including the capacitive element or the battery, or charge and discharge the circuit including the battery. A conversion circuit according to still another aspect of the present invention is a first loop circuit in which an input power supply circuit, an inductive element, and a first opening / closing means are connected in series, and the first opening / closing means includes at least a second loop circuit. A second loop circuit in which an opening / closing means and a circuit including a capacitive element or a battery are connected in series, and the input power supply circuit is controlled by controlling the opening / closing of the first opening / closing means and the second opening / closing means. It is configured to bidirectionally transfer power between circuits including the capacitive element or the battery to change the voltage of the circuit including the capacitive element or the battery, or to charge and discharge the circuit including the battery. It Here, an auxiliary power supply having a predetermined voltage may be connected in series to the second power storage means or the second loop circuit.

[0008]

In the present invention, the power supply means, the first power storage means for storing electromagnetic energy, and the second power storage means for storing electric charge are provided, and the power supply means and the first power storage means are provided. The first switching means is connected in series, the first power storage means and the second power storage means are connected in series by the second switching means, and opening / closing of the first and second switching means is controlled. , The power stored in the first power storage means from the power supply means
The electric power storage means is charged, the electric power charged in the second electric power storage means is discharged to the first electric power storage means, and the discharged electric power is regenerated to the electric power supply means.

[0009]

Embodiments of the present invention will now be described with reference to the drawings. FIG. 1 is a block diagram showing an embodiment of a conversion circuit according to the present invention. The present embodiment is a circuit that supplies a voltage obtained by stepping up or stepping down the voltage from the DC power supply 10 as the voltage supplied to the load 9 (capacitive load).
Has an amplification function.

The signal source 1 is the input signal source of the amplifier,
Output a negative polarity signal. The error amplifier 2 has a feedback element R1.
And R2 and a capacitor C3 as a phase compensation element of the negative feedback loop and a resistor R3, and is a constant voltage negative feedback amplifier which receives the negative polarity signal from the signal source 1 as an input, and detects a difference voltage between input and output. Amplify. The comparator 3 compares the triangular wave signal output from the triangular wave oscillator 4 as a carrier signal for the pulse width modulation (PWM) operation with the output signal from the error amplifier 2 and outputs a pulse corresponding to the output signal from the error amplifier 2. Output a pulse signal having a width.

The drive amplifier 6 is composed of, for example, an insulation type drive amplifier, receives the output pulse from the comparator 3 and the pulse inverted by the inverter 5 as an input, amplifies the output pulse, and, for example, a switching element including a power MOS FET. Supply to 7 and 8. Reverse switching current blocking diodes D1 and D2 are connected in series to the switching elements 7 and 8, respectively, and a diode D3 is provided.
And D4 are connected in parallel.

The load 9, the DC power supply 10 and the switching elements 7 and 8 are connected in series, and an inductor 11, which is an inductive element, is connected between the connection points. The capacitors C1 and C2 are a capacitor for smoothing the carrier frequency component and a capacitor for reducing the ripple component of the output voltage. In principle, the capacitors C1 and C2 are unnecessary if the load is a capacitor and if the equivalent series impedance of the DC power supply 10 is small.

In the circuit shown in FIG. 1, the output of the error amplifier 2 is a signal 2A corresponding to the input / output difference of the negative feedback amplifier as shown in FIG. Comparator 3
Compares this signal with the triangular wave signal 4A from the triangular wave oscillator 4, and outputs a pulse signal having a pulse width T2 and a pulse interval T1 (pulse cycle: T1 + T2) as shown in FIG. The duty of this output pulse changes according to the output of the error amplifier 2, and the PWM operation is performed.
The output of the comparator 3 is inverted by the inverter 5, and the output of the switching elements 7 and 8 becomes O as a pair of signals having opposite phases.
It is a signal for controlling N and OFF. Drive amplifier 6
, The input side circuit potential and the control terminal potentials of the switching elements 7 and 8 are different, so that it is necessary to insulate between the input and the output.

FIG. 3 shows a simplified circuit diagram in which elements related to voltage conversion are extracted from FIG. 1, and the operation principle of the circuit for stepping up or stepping down the DC voltage from the DC power supply 10 and supplying it to the load 9 is shown. This will be described below.

The inductor 11 is an inductive element that temporarily stores electric power as an electromagnetic energy, the capacitor 9 is a capacitive element that temporarily stores electric power as electrostatic energy, and the switching element 8 is a DC power supply 10 and an inductor 11. The switching element 7 serves as a path for exchanging electric power between the capacitor 9 and the inductor 11.

The average value V0 of the terminal voltage Vc of the capacitor 9 in the steady state is obtained as follows with reference to FIG. The time when the switching element 7 is OFF and the switching element 8 is ON is T1, the time when the switching element 7 is ON and the switching element 8 is OFF is T2, and the values of L and C of the inductor 11 and the capacitor 9 are LC >> {( It is assumed that T1 + T2) / (2π)} ² is satisfied. Current i flowing through inductor 11
The value at the beginning of the T1 period of L is I1, and the value at the beginning of the T2 period is I2.
Then, iL increases to iL = I1 + (E / L) t (1) during the T1 period, and I2 = I1 + (E / L) T1 (2) at t = T1. Also, during the T2 period, iL decreases to iL = I2-(V0 / L) t (3), and at t = T2 I1 = I2-(V0 / L) T2 (4), and (2), (4 ), The following equation is obtained. (V0 / E) = (T1 / T2) (5) From the equation (5), the ratio of the terminal voltage VO of the capacitor 9 and the voltage E of the DC power supply 10 is the ratio of the switching times of the switching elements 7 and 8 (duty ratio). It can be seen that Vo can be controlled from a value below E to a value exceeding E.

In the circuit described above, the operation when the capacitor 9 is charged when the switching elements 7 and 8 perform the ON / OFF operation as shown in FIG. 4 will be described. Switching element 7 is OFF, switching element 8 is ON
In one period, the gradually increasing current iL flows in the circuit composed of the DC power supply 10, the inductor 11, and the switching element 8,
The inductor 11 is charged from the DC power supply 10.
On the other hand, the switching element 7 is ON, and the switching element 8
During the T2 period when is OFF, the gradually decreasing current ic flows in the circuit including the inductor 11, the switching element 7, and the capacitor 9, the electric power stored in the inductor 11 is transferred to the capacitor 9, and is charged in the polarity state shown in the capacitor 9. To be done. The DC power supply 10 charges the capacitor 9 through the series of operations described above. Thus the capacitor 9
The voltage (output voltage) Vc appearing at both ends of the voltage gradually increases as shown in FIG.

Next, the operation when the capacitor 9 is discharged will be described with reference to FIG. Switching element 7 is O
N, during the T2 period when the switching element 8 is OFF, the capacitor 9, the switching element 7, and the inductor 1
A current ic flows through the circuit composed of 1 and the electric power stored in the capacitor 9 is transferred to the inductor 11. During the T1 period in which the switching element 7 is OFF and the switching element 8 is ON, the current iL flows through the circuit including the inductor 11, the switching element 8 and the DC power supply 10, and the electric power stored in the inductor 11 is regenerated to the DC power supply 10. To be done. Electric power is regenerated from the capacitor 9 to the input power supply 10 by the above series of operations. In this way, the voltage (output voltage) Vc appearing across the capacitor 9 gradually decreases as shown in FIG.

From the above description, electric power is bidirectionally exchanged between the DC power supply 10 and the capacitor 9, and the terminal voltage of the capacitor 9 can be controlled in either the increasing or decreasing direction, and the capacitor can be controlled. DC power supply voltage E
It will be understood from the following that it is possible to control in a wide range from the range exceeding the DC power supply voltage E.

FIG. 6 is a circuit diagram of another embodiment of the present invention that achieves a function substantially similar to that of FIG. In this figure,
The DC power supply 10 having a terminal voltage E is an input power supply, the inductor 11 having an inductance L is a circuit element having a function of temporarily storing electric power as electromagnetic energy, and the capacitor 9 having a capacitance C is storing electric power as electrostatic energy. A circuit element having a function. The switching element 8 is
The switching element 7 is a switching element serving as a path for exchanging electric power between the DC power supply 10 and the inductor 11, and the switching element 7 is a path for exchanging electric power between the capacitor 9 and the inductor 11 and the DC power supply 10. Is a switching element. This circuit is effective when the negative terminal of the load and the negative terminal of the power source must be commonly connected. Since the operation of this circuit is substantially the same as the operation of FIG. 3 described with reference to FIGS. 4 and 5, description thereof will be omitted.

The average value V0 of the terminal voltage Vc of the capacitor 9 in the steady state is obtained as follows with reference to FIG. The time when switching element 7 is OFF and switching element 8 is ON is T1, the time when switching element 7 is ON and switching element 8 is T2, and the values of L and C are LC >> {(T1 + T2) / (2π) } ² is satisfied. Inductor 11 current iL T
If the value at the beginning of the 1 period is I1 and the value at the beginning of the T2 period is I2, iL increases to iL = I1 + (E / L) t (11) during the T1 period, and I2 = I1 + at t = T1. (E / L) T1 (12). Further, during the T2 period, iL decreases to iL = I2- (V0-E) t / L (13), and at t = T2, I1 = I2-(V0-E) T2 / L (14), and (12) ) And (14), the following equation is obtained. (V0 / E) = (T1 / T2) +1 (15) From the equation (15), the ratio of the terminal voltage VO of the capacitor 9 and the voltage E of the DC power supply 10 is the ratio of the switching times of the switching elements 7 and 8 (duty Ratio), Vo is E
It can be seen that the control can be performed in a wide range exceeding the range.

In the above description, in the conversion circuits shown in FIGS. 3 and 6, if the auxiliary power source is connected in series with the capacitor 9, the terminal voltage variable range of the capacitor 9 can be expanded by the voltage of the auxiliary power source.

An amplifier circuit can be constructed by adding a control circuit, feeding back a part or all of the voltage and current of each part, and controlling the ON / OFF operation of the switching elements 7 and 8.

Although the above description has described the conversion circuit relating to voltage, it goes without saying that it can be applied to current as well.

[0025]

As described above, according to the conversion circuit of the present invention, a capacitor or a battery is charged / discharged with a simple circuit configuration, a wide range of voltage is supplied, and the voltage can be increased / decreased arbitrarily. Can be controlled.

[Brief description of drawings]

FIG. 1 is a circuit block diagram to which an embodiment of a conversion circuit according to the present invention is applied.

FIG. 2 is a diagram for explaining the operation of the conversion circuit shown in FIG.

FIG. 3 is a diagram for explaining the operation of the circuit shown in FIG.

FIG. 4 is a diagram for explaining the operation of the circuit shown in FIG.

FIG. 5 is a diagram for explaining the operation of the circuit shown in FIG.

FIG. 6 is a circuit diagram of another embodiment of the present invention that achieves a function substantially similar to that of FIG.

FIG. 7 is a diagram for explaining the operation of the circuits shown in FIGS. 3 and 6.

FIG. 8 is a diagram showing a conventional voltage conversion circuit.

[Explanation of symbols]

 1 signal source 2 error amplifier 3 comparator 4 triangular wave oscillator 5 inverter 6 drive amplifier 7,8 switching element 9 load (capacitive load) 10 DC power supply 11 inductor

Claims (5)

[Claims] 1. A power supply means, a first power storage means for storing electromagnetic energy, a second power storage means for storing electric charge, and energy between the power supply means and the first power storage means. A first switching means for exchanging energy, a second switching means for exchanging energy between the first power storage means and the second power storage means, and the first and second A conversion circuit comprising: a control unit that controls opening and closing of the second switching unit. 2. The control means supplies the power stored in the first power storage means from the power supply means via the first switching means to the second power via the second switching means. Control for charging the second power storage means, discharging the power charged in the second power storage means to the first power storage means via the second switching means, and discharging the discharged power to the first power storage means. A conversion circuit for changing the voltage of the second power storage means by performing at least one control of regeneration of the power supply means via the switching means. 3. A first loop circuit in which an input power supply circuit, an inductive element and a first opening / closing means are connected in series, and a circuit including a second opening / closing means and a capacitive element or a battery in the inductive element. A second loop circuit in which a circuit having the above is connected in series, and by controlling the opening / closing of the first opening / closing means and the second opening / closing means, the input power supply circuit and the capacitive element or battery. A voltage conversion circuit, wherein electric power is bidirectionally transmitted / received between circuits including, to change the voltage of the circuit including the capacitive element or the battery, or to charge and discharge the circuit including the battery. 4. A first loop circuit in which an input power supply circuit, an inductive element and a first opening / closing means are connected in series, and the first opening / closing means includes at least a second opening / closing means and a capacitive element or a battery. A second loop circuit in which a circuit including is connected in series, and includes the input power supply circuit and the capacitive element or battery by controlling opening / closing of the first opening / closing means and the second opening / closing means. A voltage conversion circuit, wherein electric power is bidirectionally exchanged between circuits to change a voltage of a circuit including the capacitive element or the battery, or to charge and discharge a circuit including the battery. 5. The auxiliary power source of a predetermined voltage is connected in series to the second power storage means or the second loop circuit, as claimed in claim 1, 2, 3 or 4. Conversion circuit.