JPS61173673A - Voltage controller - Google Patents

Abstract

PURPOSE:To reduce the pulsating ratio of output voltage and current and the reduction in the sensitivity at a high voltage output side by performing the ON control of switching only during a period that the momentary value of an input voltage does not arrive at the prescribed value. CONSTITUTION:A transistor 10 is turned ON during a period T10 that an input voltage Vi is pulsated so that a voltage Va exceeds a Zener voltage Vz, and a transistor 9 is turned ON during a period T9 except the period T10, an output voltage V0 supplied to a load 13 becomes a waveform as shown, and can be controlled within a range of Vi>=V0. When a voltage Vd is varied with respect to the Zener voltage Vz, the ON period T10 of the transistor 10 is varied, and the ON period T9 of the transistor 9 is further varied. Accordingly, even if an input voltage (i) is altered, the ON period T9 of the transistor 9 is automatically changed to act to hold the output voltage V0 constant.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a switching type voltage control circuit, and particularly to a voltage control circuit that controls an output voltage by switching synchronized with pulsations of an input voltage.

[Background of the invention]

In converters that obtain DC from AC, SOR and G'I'
As shown in FIG. 2, a method of controlling the output voltage by controlling the conduction angle α during a half-cycle period of AC input using a switching element such as O is widely used.

However, with this method, (1) the pulsation rate of the output voltage and current is large, and smoothing is difficult.

■ In the region where the output voltage is close to the input voltage, there is little change in the output voltage with respect to changes in the conduction angle α. In other words, control sensitivity decreases on the high output voltage side, resulting in poor controllability.

There are drawbacks such as. In Fig. 2, Vll indicates the output voltage and No indicates the output current.〇 [Object of the Invention] The object of the present invention is to eliminate the drawbacks of the prior art described above, and to provide a high-voltage system with essentially a small pulsation rate. It is an object of the present invention to provide a voltage control circuit which has a simple configuration and has little decrease in sensitivity on the output side.

[Summary of the invention]

To achieve this objective, the present invention provides the following advantages:
The device is characterized in that the switching operation is turned on when the instantaneous value of this pulsating input voltage is below a predetermined value, and turned off when it exceeds a predetermined value.

[Embodiments of the invention]

EMBODIMENT OF THE INVENTION Hereinafter, the voltage control circuit according to the present invention will be explained in detail with reference to illustrated embodiments.

FIG. 1 shows an embodiment of the present invention, in which 1 is a single-phase bridge rectifier, 2 is a variable resistor, 3 to 7 are resistors, 8 is a Zener diode, 9.10 is a transistor, 10.12
is a diode, and 13 is a load.

Next, the operation of this embodiment will be explained with reference to the waveform diagram in FIG.

When the AC voltage AO is supplied to the single-phase bridge rectifier 1, an input voltage Vi having a gold wave rectified waveform is obtained.

On the other hand, the load 13 is connected to the single-phase bridge rectifier 1 via the switching transistor 9 and the compensation diode 12.
Therefore, a voltage is applied to the load 16 only when the transistor 9 is turned on. flows, and at this time, the output voltage V supplied to the load 13 is V. is determined by the ratio of the time when transistor 9 is on and the time when it is off (
V4>To), and operates as a voltage control circuit.

The pace α of the switching transistor 9 is connected to the + side output C of the rectifier 1 via the resistor 7, and is also connected to the one side output C of the rectifier 1 via the collector-emitter of the transistor 10. , transistor 9
turns on when the transistor 10 is off, and turns off when it is on. When the Zener diode 8 becomes conductive, the transistor 10 is supplied with a pace current and turned on.

The Zener diode 8 has an input voltage V4 connected to a resistor 2.
Voltage Vd divided by 3 and taken out at point d
is supplied, and therefore, when this voltage vd exceeds its Zener voltage vz, the Zener diode 8 becomes conductive. Then, when this Zener diode 8 becomes conductive,
Since the Zener voltage ■z is divided by the resistor 5.6 and applied to the gate of the transistor 10, the transistor 10 is turned on as described above.

As a result, according to this embodiment, as shown in FIG.
In the period TIO when the input voltage vi is pulsating and the voltage Vd exceeds the Zener voltage V□, the transistor 10
is turned on, and during the other period T9, the transistor 9 is turned on, and the output voltage V is supplied to the load 13.

has a waveform as shown in Figure 3, and as mentioned above, (v
This means that it can be controlled within the range (s > vo).

The magnitude of the output voltage v0 at this time is determined by the Zener voltage v2 of the Zener diode 8 and the voltage vd at point d. That is, since the voltage vd is the voltage divided from the input voltage v4, the input voltage v1 is divided as shown in FIG.
Similarly, it has a half-cycle waveform of a sine wave. Therefore, if the voltage Vd is changed with respect to the Zener voltage V□, the on-period T10 of the transistor 10 will also change, and 9 will also change with the on-period of the transistor 9. . The state of change at this time is such that the larger the voltage vd is and the closer it is to the input voltage V(), the more the on-period 'I
'10 increases, on the contrary, the on period T9 decreases, and the output voltage V. As the voltage vd decreases, the on-period T10 decreases, the on-period T9 increases, and the output voltage v0 also increases.

Therefore, according to this embodiment, the variable resistor 2f: adjusts the output voltage V. You can change the size arbitrarily.

Furthermore, in this embodiment, if the input voltage v4 changes, the voltage Vd also changes accordingly. On the other hand, the Zener voltage vg maintains a substantially constant value regardless of changes in the input voltage v4.

Therefore, according to this embodiment, even if the input voltage V (varies) for some reason such as a change in the alternating current voltage AC, the on-period T9 of the transistor 9 automatically changes accordingly, and the output voltage v02 Since it works to maintain a constant voltage, it can also be equipped with an automatic voltage control function.

Next, in this embodiment, as is clear from FIG. 3, the output voltage V. is obtained by two conduction periods α and β within one cycle of pulsation of the input voltage vi.

Therefore, according to this embodiment, compared to the conventional example shown in FIG. Since the frequency is increased, the pulsation rate of the output voltage can be significantly reduced. Note that this is particularly noticeable when the output voltage v0 is greatly reduced, that is, when (vt > V, ).

Further, according to this embodiment, as is clear from FIG. 3, the voltage Vd is lowered and its maximum value is changed to the Zener voltage v
2, that is, the output voltage V.

When the signal input voltage is controlled to be high close to v4,
The rate of change in the on-period T10 and the on-period T9 with respect to this change in Vd is considerably large.

Therefore, according to this embodiment, the output voltage V for a change in voltage Vd. The rate of change, or control sensitivity, is the output voltage V. In the region where the value is large, a sufficiently high value can be obtained, and good controllability can be provided.

In the embodiment shown in FIG. 1, the diode 11 is provided for when the load 13 is inductive, and is a so-called flywheel diode.

By the way, in the above embodiment, as shown in FIG. 4 (α), the present invention is applied to an automatic voltage control circuit, and the input voltage v4
The output voltage V remains almost constant even when the voltage fluctuates. However, the present invention is not limited to this, and can also be applied to a voltage regulating circuit for a generator, as shown in FIG. 4(b). In FIG. 4(b), 14 is the armature coil of the single-phase alternating current generator, 15 is the excitation filter thereof, and A indicates the circuit of the embodiment shown in FIG. 1.

In this embodiment, if the AC output voltage decreases for some reason, such as an increase in the load connected to the AC output, the input voltage vi also decreases accordingly. Then, as explained in Fig. 3, the transistor 9
The conduction time T9 of V is increased, thereby increasing the output voltage V. increases, the current flowing through the excitation coil 15 increases, and A
Compensates for the drop in C output voltage. On the other hand, if the AO output voltage increases, current flows through the excitation coil 15. is reduced to compensate for the increase in the AC output voltage in the same way, eventually allowing the generator's AO output voltage to remain approximately constant. Note that such single-phase alternating current generators are widely used in, for example, wind power generators.

According to the embodiment shown in FIG. 4(b), the pulsation rate of the current flowing through the excitation coil 15 is reduced, and therefore the pulsation of the AC output can be reduced.

〔Effect of the invention〕

As explained above, according to the present invention, the fundamental wave frequency of the frequency component included in the output waveform can be increased, and the conduction time of switching can be made longer than the conventional technology for the same output voltage. It is possible to easily provide a voltage control circuit that can obtain the excellent effects listed below, excluding the technical drawbacks.

■ The closer the output voltage is to the input voltage, the greater the change in output voltage with respect to the switching conduction time, and the higher the controllability.

■ Output pulsation rate can be reduced for the same AC input voltage.

■ Easy to smooth due to high pulsation frequency.

■ The smoothing circuit is small and low cost.

■ When applied to voltage control of a generator, the pulsation rate of the output voltage can be reduced and the rate of voltage fluctuation can also be reduced.

■ In the case of reactive loads, the ripple rate can be particularly small.

(2) Even in a region where the output voltage is considerably lower than the input voltage, the pulsation rate can be suppressed to a low level, and therefore the control range of the output voltage can be sufficiently widened.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram showing an embodiment of the voltage control circuit according to the present invention, FIG. 2 is a waveform diagram showing the principle of voltage control using conventional phase control, and FIG. 3 is a diagram showing the operation of an embodiment of the present invention. Explanation T
The waveform diagrams shown in FIGS. 4(α) and 4(b) are explanatory diagrams showing an example of application of the present invention. DESCRIPTION OF SYMBOLS 1... Single-phase bridge rectifier, 8... Zener diode, 9... Switching transistor, 10...
...control transistor, 13...load. Figure 1 Figure 2 Figure 3

Claims (1)

[Scope of Claims] 1. In a voltage control circuit that controls the output voltage by switching in synchronization with the pulsations of the input voltage, a detection means that continuously detects the instantaneous value of the input voltage and compares it with a predetermined value. 1. A voltage control circuit comprising: a voltage control circuit configured to perform switching-on control only during a period when an instantaneous value of an input voltage does not reach the predetermined value; 2. The voltage control circuit according to claim 1, wherein the input voltage is a single-phase full-wave rectified voltage.