JPH02294272A - Rectifying circuit - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Industrial Icheon Field] The present invention... Full wave AC voltage! i! This is a rectifier circuit that obtains a DC voltage by flowing current, and is particularly concerned with rectifier circuits in which the AC voltage fluctuates greatly. [Prior Art] What is the power source for electrical equipment used in aircraft? Since an engine generator is used, there are momentary power interruptions in the human voltage, and it takes about one second for the voltage to reach a steady state after a momentary interruption. During this time, huge amounts of capacitors and batteries are required to maintain the operation of electrical equipment. Especially in the case of aircraft, this is because they are used under fairly low temperature conditions.
It cannot operate with normal batteries. This requires a special battery, which is expensive. For this reason. In order to reduce the capacitor capacity of the instantaneous interruption compensation river. It becomes necessary to start operating the equipment from the moment the generator starts operating. However, the voltage at the start of the generator's operation is approximately 172V at steady state, and if this voltage were used as the operating voltage of the equipment, the voltage would be more than twice as high during steady state, which is not desirable. on the other hand. Single-phase commercial AC voltage varies by country around the world.
Because it covers a wide range from Porto to 240 volts. In order to use these voltages in common, we changed the rectification method of the electric 1i converter.
OO port is a voltage doubler, 200 volts is a bridge! There is a method known in the art to use i-current, and while the output voltage of the generator is low, voltage doubler rectification is used. Bridge rectification can be considered when the voltage is in a steady state. Conventional voltage doubler bridge! i! There is a method for changing the flow as shown in Figure 5. Explain according to this diagram. In the same figure. When the voltage of AC power all is low, switch 2
is closed, and a voltage approximately twice the peak voltage of the AC voltage is generated across the capacitor 3.4. Also, AC 11
! When the voltage of source 1 is high, switch 2 is opened. This is normal full-wave rectification, and almost the peak voltage of the AC voltage is generated across capacitors 3 and 4. By opening and closing the switch 2 in this way, even if the human power voltage changes twice, the change in the rectified output voltage can be reduced. still. 5～
8 is a diode. however. This method has the problem that if the switch moat is made incorrectly, excessive voltage will be generated at the output. Therefore.゛An example of the circuit shown in Fig. 6 is published in Japanese Patent Application Laid-Open No. 63-302.
It is disclosed in Publication No. 762. This method uses triarchs instead of switches. UJT rectified output voltage
Detect it with . It automatically controls the triac gate using V4, and will be explained with reference to the diagram below. ! ! The DC voltage of the current circuit is connected to resistors 9, 10 . 11 and apply the voltage of resistor l1 to the gate of tJJT12. Node 7 is connected to the cathode of Zener diode 14 via resistor l3. Therefore, the gate voltage of UJT12 is proportional to the DC output voltage. The anode voltage is clamped to the Zener voltage. When the AC input voltage is 200 volts. The resistors 9, 10 .
If 11 is set, UJT12 is turned off, transistor l5 cannot conduct, and no voltage is applied to the gate of trifuku l6. Triafuku l6 is off. ! !
! The current circuit is bridge rectification. In addition, when the AC input voltage is 100 volts, the resistor 9. 10. 11, the gate of UJT12 is triggered and becomes conductive. A voltage is generated across the resistor l7. Transistor [
5 conducts to trigger the trybook gate. Make it conductive. As a result. It becomes a voltage doubler rectifier circuit. in this way. It detects the output voltage and switches automatically. Accidents due to malfunction can be prevented. still. l8 is a capacitor. 19~2l is the resistance. [Problems to be solved by the invention] However, with such conventional rectifier circuits. The example in Figure 5 is a malfunction. In the example of the m6 diagram, there are many parts for $I1. Also, because the forward voltage drop is large, there is a drawback that there is a large loss at low voltage output. Moreover. Conventional methods respond to changes in digital input voltage, so
It is not suitable for cases where changes occur analogously, such as in aircraft engine generators. 91 For example, in the example shown in Figure 6, once the UJT is turned on, it self-holds and remains in voltage double rectification mode. When the input voltage rises slowly from a low value, it becomes impossible to switch to bridge rectification and lower the DC output voltage. (Means for Solving the Problems) The present invention aims to eliminate the above drawbacks. In a rectifier circuit with a 2111 smoothing capacitor connected in series between the DC output terminals of a rectifier bridge circuit that full-wave rectifies an AC voltage, series connection of FETs connected in series in opposite directions with the source as a common connection point. The drain on one side of the body and the drain on the other side. The connection points of the smoothing capacitors above, respectively!
In addition to connecting to either one of the AC input terminals of the AD Britsuno circuit. The gate of the husband k of the series connection body of the above FETs.
The present invention provides a rectifier circuit characterized in that the sources are connected so that the voltage between the DC output terminals is reverse biased when it is above a set value, and is biased in time order when the voltage between the DC output terminals is below the set value. {Function) The present invention has the above structure. Even when the AC input voltage changes in an analog manner, it is possible to switch between voltage doubler and one-bridge rectification. [Example] Figure 1 is a diagram showing an example of the present invention. In the same figure, the AC fL power supply ■ is connected to the AC input terminal of a bridge rectifier circuit composed of diodes 5 to 8. A series connection circuit of 3.4 smoothing capacitors is connected to the DC output of the alternating current circuit. Connect the series connection point of smoothing capacitor 3.4 and one end of the AC input terminal of the rectifier bridge to N ” F E T22
．． 23 is connected to each drain of a series circuit connected in series in opposite directions with the source as a common connection point. Connect a resistor 24, a Zener diode 25, and a low resistor 26 between the DC output terminals. A pace emitter of an NPN transistor 27 is connected to both ends of the resistor 26. The collector of transistor 27 and the positive side of the DC output are connected through a resistor, and the collector of transistor 27 is connected to the gates of FETs 22 and 23. The sources of FETs 22 and 23 are connected to the negative side of the DC output via a resistor 29. next. Let us explain the work of this example. First of all. If the DC output voltage is low and the Zener diode 25 cannot conduct. Since no voltage is generated between the base and emitter of transistor 27, transistor 27 is off. Then... FE
722.23 has a low resistance of 2B between the gate and source. Since it is forward biased through 29. FE722. 23 is conductive, and the connection point of smoothing capacitor 3.4 is connected to one end of the AC input terminal of the rectifier bridge, resulting in voltage double rectification.
The output voltage is approximately twice the peak voltage of the AC voltage. And FET22. 23 is conductive, the source potential becomes the series connection point of smoothing capacitor 3.4, and the gate-source voltage becomes 1/2 of the DC output voltage. still. FE”
r allows current to flow in both directions between the drain and source, and the voltage drop is determined by the on-resistance. For low voltage output, by using elements with low on-resistance, the voltage drop can be made smaller than with a trifle. next. When the output voltage is high (when the Zener diode 25 becomes conductive, current flows into the base of the transistor 27). Transistor 27 becomes conductive. Since the gate and source of FETs 22 and 23 are short-circuited through the resistor 29 and turned off, the series connection point of the smoothing capacitors 3 and 4 and one end of the AC input terminal are disconnected, resulting in bridge rectification, and the DC output voltage is This is approximately the peak voltage. FIG. 2 is a diagram for explaining one embodiment of 41 of the present invention. In the figure, when the DC output voltage is low, the Zener diode 25 is turned off and the transistor 30 is turned off. As a result. No base current is supplied to transistor 3l. Transistor 31 is off. Is there a base for transistor 27 as well? Since l is not supplied. Transistor 27 is also off. As a result. FE722.23
The gate of is forward biased by the resistor 2829 and becomes conductive, and the series connection point of the smoothing capacitor 34 and one end of the AC input terminal are connected. It becomes a voltage doubler rectifier circuit. next. When the DC output voltage increases, the Tsuena diode 25 becomes conductive. By supplying base current to the transistor 30, the transistor 30
Turn on. Then, the base il is connected to the transistor 3l.
Because l flows. Since the transistor 31 is turned on and the base current is supplied to the transistor 27. The transistor 27 is turned on and the gates of the FETs 22 and 23 are short-circuited via the resistor 29. The FET22. 2
3 goes off, bridge! φ replaces lfi. here,
When the transistor 3l becomes conductive. The base fa current flows into the transistor 30 via the resistor 32, and positive feedback is applied.
Then... Even if the DC voltage drops and the Zener diode 25 turns off. Since base current is supplied to transistor 30 through resistor 32, transistor 30 remains conductive and FETs 22 and 23 remain off. Then, the DC output voltage drops significantly. When the voltage drop across resistor 26 drops to the point where transistor 30 can no longer remain conductive, transistor 30 turns off. transistor 31
．． 27 is turned off, and FETs 22 and 23 are conductive. φ is replaced by voltage doubler rectification. Also. The resistance value of the resistor 24 is Rl.
Set the resistance value of tlt resistor 26 to R2. The resistance value of resistor 32 is R3
Let the voltage of the Zener diode 25 be v4, and the base-to-emitter voltage for making the transistor 30 conductive be v5.
If the DC output voltages when the transistor 30 turns on and off are V6 and V7, respectively, v6≧V4+ (R1+R2) V5/112v1;=
(R2+R3)ν5/R2, and by selecting the resistance value so that V6>2V7, even if the AC input voltage changes in an analog manner, chattering will not occur when switching between voltage doubler rectification and bridge rectification. There is no. Note that 33 to 36 have low resistance. FIG. 3 shows another embodiment of the present invention. This example is. In contrast to Figure 2, where N-type FETs 22 and 23 were used. It uses P-type FE737 and 38, and is almost the same as that described in the embodiment shown in FIG. 2, and the same effect can be obtained. 39. 40
is resistance. Figure 4 shows that the DC output voltage is high <. To protect the gate if the breakdown voltage between the gate and source of the FET is exceeded. Gate·
A Zener diode (4l) is connected between the faces. This embodiment is also almost the same as described above, and the same effects can be obtained. [Effects of the Invention] As explained above, according to the present invention, even when the AC input voltage changes in an analog manner. It is possible to switch between voltage doubler and bridge rectification. In addition, the voltage drop is reduced and the drive is simplified. The circuit configuration becomes oil-only, reducing the number of parts. Furthermore. By providing hysteresis characteristics to the detection of the voltage between the DC output terminals. Even if the AC input voltage changes analogously. Eliminates chattering when switching between voltage doubler rectification and bridge rectification. In addition, in the case of triacs, when the temperature is as low as -55°C. However, a significant amount of gate drive ftIIL is required. FET is driven by insulation. It has the advantage of requiring much less driving power than the Triafuku.

[Brief explanation of drawings]

FIG. 1 is a diagram for explaining one embodiment of the present invention, and FIGS. 2 to 4 are diagrams for explaining other embodiments of the present invention, respectively. Figures 5 and 6 are diagrams for explaining conventional examples. l...AC fa source 2...switch 3.4
...Capacitor 5-8...Diode 9-l1
...Resistor l2...UJTl3...Resistor l4...Zena diode l5...
Transistor 17... Resistor 19-21... Resistor 24... Resistor 26... Resistor 28. 29...Resistance 32-36...Resistance 39. 40...Resistor l6...Triafuku l8...Capacitor 22. 23... N-type FET 25... Zener diode 27... Transistor 30. 31...Transistor 37. 38...P-type FET 41...Zena diode

Claims (3)

[Claims] (1) In a rectifier circuit in which two smoothing capacitors are connected in series between the DC output terminals of a rectifier bridge circuit that full-wave rectifies an AC voltage, the two smoothing capacitors are connected in series in opposite directions with the source as a common connection point. F
Connecting one drain and the other drain of the series-connected ET to the connection point of the smoothing capacitor and either one of the AC input terminals of the rectifying bridge circuit, respectively, and connecting each of the series-connected FETs between the gate and source of
A rectifier circuit, characterized in that the rectifier circuit is connected so that it is reverse biased when the voltage between the DC output terminals is above a set value, and is sequentially biased when it is below the set value. (2) In a rectifier circuit in which two smoothing capacitors are connected in series between the DC output terminals of a rectifier bridge circuit that full-wave rectifies an AC voltage, a hysteresis characteristic is provided to the detection of the voltage between the DC output terminals. A rectifier circuit characterized by: (3) In the rectifier circuit according to claim 1, the FE
A rectifier circuit characterized in that a Zener diode is connected between the gate and source of a T.