JPS60247720A - Direct current power unit - Google Patents

Abstract

PURPOSE:To reduce noises and loss by providing a capacitor input type double voltage rectifying circuit, comparing a detected voltage obtained by converting a load current into a voltage with the AC voltage of an AC power source as a reference voltage, and controlling the opening and closing of the switching element of a chopper. CONSTITUTION:The AC voltage V1 of the AC power source 1 is applied across a capacitor C9 through a full-wave rectifying circuit 4 and diodes 7 and 8. The chopper 18 consists of transistors TR16 and TR17 and a positive and a negative half-wave current are flowed from the power source 1 to a reactor 15 interposed between the power source 1 and a load 10. A current transformer 19 converts the load current into the voltage and this detected voltage Va is compared by a control circuit 20 with the AC voltage Vi, i.e. reference voltage Vb. The circuit 20 controls the on-off states of the TRs 16 and 17 so that the load current follows up the waveform of the AC voltage V1, compensating reactive electric power. Thus, the frequencies of switching of the TRs 16 and 17 and the quantity of the current are reduced to reduce switching noises and loss.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a DC power supply device equipped with a capacitor input type voltage doubler rectifier circuit and having a reactive power compensation function.

[Technical background of the invention]

A DC power supply equipped with a capacitor input type rectifier circuit that supplies DC voltage to a load connected in parallel to a capacitor is being considered to be equipped with a reactive power compensation circuit, also known as a power factor correction circuit. .

Therefore, as a conventional reactive power compensation circuit, a reactor is installed between a full-wave rectifier circuit that rectifies the AC voltage of a single-phase AC power supply and a load that is parallel to a capacitor to which the DC voltage from the full-wave rectifier circuit is applied. A step-up chopper consisting of a transistor and a switching element is interposed, and a shunt resistor is inserted in the DC circuit between the full-wave rectifier circuit and the chopper, and the load current is detected as a voltage based on the shunt resistor. A control circuit is provided that compares the detected voltage with a reference voltage obtained by full-wave rectification of the AC voltage of the single-phase AC power supply, and this control circuit turns on and off depending on the magnitude relationship between the reference voltage and the detected voltage. obtaining a signal, thereby turning on and off a transistor of the chopper, increasing the current flowing through the reactor when the transistor is on;
~When the transistor is off, the electromagnetic energy stored in the reactor is applied to the capacitor, thereby causing the load current to follow the waveform of the reference voltage (AC voltage of a single-phase AC power supply).

[Problems with background technology]

When trying to obtain a particularly high DC voltage with the above conventional configuration, the boost energy must be obtained only from electromagnetic energy from the reactor, so the boost voltage must be maintained over the entire cycle of the input voltage (AC voltage of a single-phase AC power supply). Therefore, there is a problem that the switching noise and switching loss of the transistor become large, and that a transistor with a large rated capacity must be used as the transistor.

[Object of the Invention] The present invention has been made in view of the above circumstances, and its object is to provide a DC power supply that can reduce switching noise and switching loss of switching elements in a chopper, and that requires only a small rated capacity as a switching element. We are in the process of providing equipment.

[Summary of the invention]

The present invention provides a capacitor input type A8 voltage rectifier circuit that voltage doubles the AC voltage of an AC power source and supplies the DC voltage obtained to the load, and is provided with a capacitor input type A8 voltage rectifier circuit that is interposed between the AC power source and the load, The reactor is provided with a chopper consisting of first and second switching elements for flowing a positive half-wave current and a negative half-wave current from the AC power source, respectively, and a detection means for converting the current into voltage is connected to the AC power source and a voltage doubler rectifier. The AC voltage of the AC power source is used as a reference voltage, and this reference voltage is compared with the detection voltage of the detection means to turn on the first and second switching elements of the chopper. , which is characterized by a configuration in which a control circuit that outputs an OFF signal is provided, and is intended to obtain a high DC voltage using both electromagnetic energy and electrostatic energy.

[Embodiments of the invention]

A first embodiment of the present invention will be described below with reference to FIG.

Reference numeral 1 denotes a single-phase AC power source, both terminals of which are connected via AC lines 2 and 3 to an AC input terminal of a full-wave rectifier circuit 4 formed by bridge-connecting diodes 41 to 44. The positive and negative DC output terminals of the full-wave rectifier circuit 4 are connected to a DC line 5.6. Furthermore, the DC circuits 5 and 6 are connected to input capacitors 9, which are connected in parallel through reverse current blocking diodes 7 and 8, respectively. load 10
are connected to one common connection point and the other common connection point, respectively. A series circuit of voltage doubler capacitors 11 and 12 is connected in parallel to the input capacitor 9, and these voltage doubler capacitors 11
and 12 common connection points are connected to the AC line 3, and the above full-wave rectifier circuit 4. Backflow blocking diode7.
8. Input capacitor 91 times voltage capacitor 1
1 and 12 constitute a capacitor input type voltage doubler rectifier circuit 13.

Now, the reactive power compensation circuit 14 will be described. 15 is a reactor interposed in the AC line 2; 16 and 17 are first reactors;
and NPN type first and second transistors, which are second switching elements, forming a boosting chopper 18. The collector of the first transistor 16 is connected to the DC circuit 5,
The emitter is connected to the AC line 3 , the collector of the second transistor 17 is connected to the AC line 3 , and the emitter is connected to the DC line 6 .

Reference numeral 19 denotes a current transformer as a detection means disposed in the AC line 3, which converts the load current 11 flowing through the AC line 3 into an AC voltage and supplies it to the detection terminal a of the control circuit 20 as a detection voltage Va. It looks like this. Further, the reference terminal Ib of this control circuit 20 is connected to the AC voltage V1 of the single-phase AC power supply 1.
The control circuit 20 appropriately steps down the AC voltage v1 to obtain the reference voltage vb. The control circuit 20 controls the reference voltage IVb when the reference voltage Vb is a positive half wave or a negative half wave.
l is larger than the detection voltage 1Val (IVbl>1Val)
, a high-level ON signal @Sa or sb is output from the output terminal Qa or Ob, and the transistor 16
Alternatively, when the reference voltage IVbl is smaller than the detection voltage IVal (lVb 1lVa l), the output of the on signal Sa or sb is stopped (output of an off signal).

Next, the operation of this embodiment will be explained.

The AC voltage v1 of the single-phase AC power supply 1 is full-wave rectified by the full-wave rectifier circuit 4 and converted into a DC voltage by the reverse current blocking diode 7.
．． 8 between both terminals of the input capacitor 9, and on the other hand, during the positive half wave of the AC voltage V1, the reactor 1
5. The voltage doubler capacitor 11 is charged in the illustrated polarity to the peak value aV1 of the positive half wave in the path of the diode 41°7, the voltage doubler capacitor 11, and the AC line 3, and the AC line 31 is charged at the negative half wave of the AC voltage Vl. Voltage doubler capacitor 1
2. Diode 8, 4. And in the route of the reactor 15, the peak value fl of the negative half wave is applied to the voltage doubler capacitor 12 with the polarity shown.
-Vt, resulting in a load of 2aV
A DC voltage of t is applied, and AC lines 2 and 3 respond accordingly.
An alternating current load current I+ flows through. Therefore, the control circuit 20
For example, during the positive half wave of the AC voltage V1, that is, the reference voltage Vb, when the reference voltage IVbl is larger than the detection voltage IVal, outputs a high-level on signal Sa to turn on the first transistor 16, Therefore, reactor 1
5. Diode 41. Transistor 16 and AC line 3
The current flowing through the reactor 15 increases through the path, and electromagnetic energy is stored in the reactor 15. As a result, the load current ■l also increases, so the detection voltage Va increases, and as a result, the detection voltage IVal increases to the reference voltage 1v.
When it becomes larger than b1, the output of the on signal Sa is stopped and the first transistor 16 is turned off. When the first transistor 16 is turned off, the load current decreases and the electromagnetic energy stored in the reactor 15 is applied to the voltage doubler capacitor 11 via the diodes 41 and 7.

Thereafter, similar operations are repeated. Further, during the negative half wave of the AC voltage Vl, the control circuit 20 outputs a high-level on signal sb when the detected voltage 1Val is smaller than the reference voltage IVbl, as described above, to turn on the second transistor 1.
7 on the line, and therefore the AC line 3. Transistor 17. The N flow flowing into the reactor 15 increases through the path of the diode 43 and the reactor 15, and electromagnetic energy is stored in the reactor 15. As a result, the load current 11 also increases, so the detection voltage va increases, and when the detection voltage IVal becomes larger than the reference voltage IVbl, the output of the on signal S1) is stopped and the second
transistor 17 is turned off. second transistor 1
7 is turned off, the load current 11 decreases and the electromagnetic energy stored in the reactor 15 is transferred to the diode 4.
3 and 8 to the voltage doubler capacitor 12.

Thereafter, similar operations are repeated, and as a result, the load current (1) follows the waveform of the AC voltage Vl, and reactive power is compensated for.

In addition, due to the above-mentioned operation, 2 f from the AC voltage v1
When obtaining a high DC voltage of 7-V1, there will be a period in which the DC voltage is lower than the AC voltage v1, and there is no need to boost the voltage by the chopper 18 during this period. In particular, the transistor 16.17 near the peak value of the AC voltage Vl ((T V 1)
This means that the number of switching times can be reduced.

According to this embodiment, the following effects can be obtained. That is, when obtaining a high DC voltage of 2 (NV The degree of dependence on electromagnetic energy can be significantly reduced, and therefore the number of times of switching and the amount of current of the first and second transistors 16 and 17 of the chopper 1B can be reduced, thereby reducing switching noise and switching loss. In addition, there is an advantage that only transistors with small rated capacities can be used as the first and second transistors 16 and 17.Especially when obtaining a DC voltage of 2 tT V l from an AC voltage Vt. Since this mainly depends on the electrostatic energy of the voltage doubler capacitors 11 and 12, there is an advantage that a DC voltage/voltage of this value can be obtained after the power is turned on.

FIG. 2 shows a second embodiment of the present invention, and the same parts as in the previous embodiment are designated by the same reference numerals, and only the parts that are the same will be described below.

In this embodiment, the first and second transistors 16 and 1
7 to the AC line 2.3 side, and the first transistor 16
The collector of the first transistor 16 and the emitter of the second transistor 17 are connected to a part of the AC bus 2 closer to the full-wave rectifier circuit 4 than the reactor 15, and the emitter of the first transistor 16 and the collector of the second transistor 17 are connected to the AC line 3. It is characterized by the points connected to it. In FIG. 2, the backflow blocking diodes 7 and 8 are not necessary.

The operation of this second embodiment is similar to the previous embodiment, but if the chopper 18 is disposed on the AC line 2.3 side as in this embodiment, the voltage can be n times higher than 3 times the voltage. It is also applicable to

In the first embodiment, the beam reactor 15 was interposed in the AC line 2, but instead, as in the third embodiment of the present invention shown in FIG. and a common connection point between the emitter of the transistor 16 and the collector of the transistor 17.

In addition, the present invention is not limited only to the embodiments described above and shown in the drawings, and it goes without saying that the present invention can be implemented with appropriate modifications within the scope of the invention.

〔Effect of the invention〕

As explained above, the DC power supply device of the present invention includes a capacitor input type voltage doubler rectifier circuit, a chopper including a reactor and first and second switching elements, a detection means for converting a load current into a voltage, and an AC A control circuit is provided which uses the AC voltage of the power source as a reference voltage and compares it with the detection voltage of the detection means to output ON/OFF signals for the first and second switching elements of the chopper. Since it is made to follow the AC voltage waveform, it is possible to reduce the switching noise and switching loss of the first and second switching elements, and it has the excellent effect of requiring only a switching element with a small rated capacity. It is.

[Brief explanation of drawings]

FIGS. 1, 2, and 3 are electrical circuit diagrams showing first, second, and third embodiments of the present invention, respectively. In the drawing, 4 is a full-wave rectifier circuit, 9 is an input capacitor, 10 is a load, 11 and 12 are voltage doubler capacitors,
13 is a voltage doubler rectifier circuit, 14 is a reactive power compensation circuit, 15
1 is a reactor, 16 and 17 are first and second transistors (first and second switching elements), 1 is a chopper, 19 is a current transformer (detection means), and 20 is a control circuit. Figure 2 (21)

Claims (1)

[Claims] 1. A capacitor input type voltage doubler rectifier circuit that voltage doubles and rectifies the AC voltage of an AC power source and supplies the DC voltage obtained to the load, a reactor interposed between the AC power source and the load, and a reactor that supplies the AC voltage to the reactor. A chopper is provided in an AC line between the AC power source and the voltage doubler rectifier circuit, and is configured to convert the current into a voltage. a detection means for converting the AC voltage of the AC power source into a reference voltage, and compares this reference voltage with the detection voltage of the detection means to turn on the first and second switching elements of the chopper;
A DC power supply device comprising a control circuit that outputs an off signal.