JPH0720371B2 - DC power supply - Google Patents

Description

TECHNICAL FIELD The present invention relates to a DC power supply device capable of easily achieving improvement of a current waveform in an AC input line.

[Conventional technology]

In order to correct the distortion of the current waveform of the AC input line based on the ON / OFF operation of a switching element such as a switching regulator or an inverter connected to the rectifier circuit,
Connect the reactor to the power supply line and turn on the switching element connected between the pair of DC output lines of the rectifier circuit.
It is known to control the off state (for example, JP-A-63-1905).
No. 57).

[Problems to be Solved by the Invention]

By the way, in the conventional device, it is necessary to form a signal corresponding to the difference between the output voltage and the reference voltage and to multiply this signal by the reference sine wave, which inevitably leads to a complicated circuit configuration and high cost. Natsuta.

Then, the objective of this invention is providing the direct-current power supply device which can reduce cost.

[Means for Solving the Problems]

According to a first aspect of the present invention to achieve the above object, an AC power supply terminal, a rectifier circuit connected to the AC power supply terminal, and an AC power supply line between the AC power supply terminal and the rectifier circuit are connected in series. Alternatively, an inductance circuit element connected in series and / or in parallel to a DC output line of the rectification circuit, and an ON / OFF operation having a cycle shorter than the cycle of the AC voltage of the AC power supply terminal, the inductance circuit element In a DC power supply device having a switching element for controlling the accumulation and release of energy to and from the switching element, and a smoothing capacitor provided on the output side of the switching element, voltage detection for detecting a DC output voltage smoothed by the smoothing capacitor A circuit, a current detector for detecting a current flowing through the switching element or the reactor, and a reference voltage source A difference signal forming circuit that forms a voltage corresponding to the difference between the reference voltage of the reference voltage source and the detection voltage obtained from the voltage detection circuit, and a triangular wave at a frequency sufficiently higher than the AC voltage of the AC power supply terminal. A triangular wave generating circuit, a combining circuit that forms a combined voltage of the output voltage of the difference signal forming circuit and the triangular wave, a current detection waveform obtained from the current detector, and a combined voltage obtained from the combining circuit. A voltage comparator that generates a voltage comparison output, a set signal generation circuit that generates a set signal in synchronization with the triangular wave, and a voltage comparator that indicates that the current detection waveform has reached the composite voltage. And a reset signal generating circuit for generating a reset signal in response to the set signal obtained from the set signal generating circuit. And a flip-flop circuit that is in a reset state in response to the reset signal obtained from the signal generation circuit and that outputs an output pulse indicating the set state to the control terminal of the switching element as an ON control pulse of the switching element. The present invention relates to a DC power supply device. In addition,
The inductance circuit element is, for example, a reactor or a transformer. The difference signal forming circuit is, for example, the differential amplifier (error amplifier) 22 of the embodiment.

In the invention according to claim 3, the control value is controlled by comparing the composite value of the triangular wave and the current detection waveform with the differential output.

In the invention according to claim 5, the inclination of the triangular wave is controlled by the differential output.

In the invention according to claims 2, 4, and 6, the inclination of the triangular wave is controlled based on the average value of the AC voltage.

[Work]

In the invention of any of the claims, the current waveform can be improved without using the reference sine wave and the multiplier.
Further, the current waveform and the power factor can be improved with a relatively simple circuit.

[First Embodiment] Next, a DC power supply device according to a first embodiment of the present invention will be described with reference to FIGS. 1 and 2. This device has a pair of AC power supply terminals 1 and 2 to which a commercial AC power supply of, for example, 50 Hz is connected. The high frequency removing filter 3 connected to the power supply terminals 1 and 2 includes reactors 4 and 5 connected in series to the line and a capacitor 6 connected between the pair of lines.
7 and 7.

A full-wave rectifier circuit 8 is connected to the output stage of the filter 3. A reactor 13 as an energy storage element and a reverse current blocking diode 14 are connected in series to one of the pair of DC lines 11 and 12 between the rectifier circuit 8 and the pair of DC output terminals 9 and 10. A switching element 15 composed of a FET and a current detection resistor 16 as a current detector are connected between the output terminal of the reactor 13 and the lower DC line 12. The smoothing capacitor 16a is connected between the output terminals 9 and 10 at the output stage of the reverse current blocking diode 14.

A voltage detection circuit 19 composed of resistors 17 and 18 is connected between output terminals 9 and 10, and this voltage detection line 20 is connected to one input terminal of a differential amplifier 22 of a switching element control circuit 21. The other input terminal of the differential amplifier 22 has a reference voltage source.
23 is connected.

The current detection line 24 derived from one end of the current detection resistor 16 is connected to one input terminal of the voltage comparator 25. The other input terminal of the voltage comparator 25 is connected to the triangular wave (sawtooth wave) of the triangular wave generating circuit 26 and the differential amplifier 22.
A combining circuit 29 including resistors 27 and 28 for obtaining a combined waveform with the differential output of is connected.

The control pulse forming circuit 30 comprises an RS flip-flop 31, a set signal generating circuit 32, and a reset signal forming circuit 33. The set signal generating circuit 32 forms a set trigger signal in synchronization with the triangular wave of the triangular wave generating circuit 26, and supplies this to the set terminal S of the flip-flop 31. Although FIG. 1 shows that the set signal generation circuit 32 is controlled by the triangular wave generation circuit 26, a reference oscillator is built in the set signal generation circuit 32, and the flip-flop 31 of the flip-flop 31 is generated based on the output clock of the reference oscillator. The triangular wave generating circuit 26 may be controlled while forming the set signal. The reset signal forming circuit 33 applies a reset trigger pulse to the reset terminal R of the flip-flop 31 in response to the change of the output state of the comparator 25. The Q output terminal of the flip-flop 31 is connected to the control terminal (gate) of the switching element 15 composed of FET.

〔motion〕

Next, the operation of the circuit shown in FIG. 1 will be described with reference to the waveforms shown in FIG. When a sinusoidal AC voltage is applied to the power supply terminals 1 and 2, the full-wave rectified voltage waveform shown in FIG. 2A is obtained at the output stage of the rectifier circuit 8. This voltage waveform is the switching element
If the switching element 15 is interrupted at a frequency sufficiently higher than the power supply frequency (for example, 20 kHz of several Hz or more), the switching element 15 has an amplitude (peak) corresponding to the amplitude of the voltage waveform as shown in FIG. 2 (B). Electric current flows intermittently. As a result, the waveform of the current flowing through the power supply terminals 1 and 2 becomes an approximate sine wave corresponding to the voltage waveform as shown in FIG. 2 (C).

By the way, it is desirable that the duty of the control pulse for intermittently controlling the switching element 15 is small when the amplitude of the sine wave is large, and is large when the amplitude is small in order to bring the current waveform close to the sine wave. It is desirable that the switching element 15 is used not only for improving the current waveform but also for controlling the output voltage in order to simplify the circuit configuration. In order to achieve these, the current detection waveform is input to the comparator 25, and the composite wave of the triangular wave and the differential output is input.

Since the reactor 13 is provided, the current flowing through the switching element 15 increases with time during the ON period of the switching element 15, as shown in FIG. 2 (B). During the OFF period of the switching element 15, the energy stored in the reactor 13 is given to the capacitor 16a through the diode 14. This time,
Since the capacitor 16a is charged with the sum of the voltage of the reactor 13 and the power supply voltage, the charging voltage of the capacitor 16a becomes higher than the power supply voltage. The DC voltage shown in FIG. 2 (D) obtained between the output terminals 9 and 10 is compared with the DC reference voltage of the reference voltage source 23, and the differential output voltage corresponding to the difference is shown in FIG. 2 (G). Is obtained as As shown in FIG. 2 (F), a triangular wave (sawtooth wave) having a downward slope is obtained from the triangular wave generating circuit 26 at a high frequency (for example, 20 kHz). The triangular wave of FIG. 2 (F) is combined with the differential output of FIG. 2 (G) to form a combined wave shown by the solid line of FIG. 2 (H),
This becomes the input of the comparator 25. The comparator 25 compares the current detection waveform shown in FIG. 2 (B) (the waveform shown by the dotted line in FIG. 2 (H)) with the sawtooth wave shown in the solid line in FIG. When it reaches, the output of the comparator 25 is converted, and the reset trigger pulse shown in FIG. 2 (I) is obtained at the output line of the reset signal forming circuit 33. From the set signal generation circuit 32, a set trigger pulse is generated in synchronization with the rising edge of the triangular wave as shown in FIG. As a result, the control pulse shown in FIG. 2 (J) is generated from the flip-flop 31, and the switching element 15 is turned on / off correspondingly. Comparator 25
Since the current detection waveform of the switching element 15 whose peak value changes with respect to the amplitude of the sine wave voltage is input to, the duty of the control pulse of the switching element 15 decreases during the period when the amplitude of the AC voltage is large, and conversely. When the amplitude of the AC voltage is small, the duty of the control pulse becomes large. Further, the duty of the control pulse changes in inverse proportion to the output voltage.

As described above, according to this embodiment, the input current waveform and the power factor can be improved without using the multiplier.

[Second Embodiment] Next, a DC power supply device according to a second embodiment will be described with reference to FIGS. 3 and 4. However, in FIGS. 3 and 4, and FIGS. 5 to 14 shown later, the same reference numerals are given to the substantially same parts as those in FIGS. 1 and 2, and the description thereof will be omitted.

In the circuit of FIG. 3, in order to synthesize the triangular wave having the upper right slope of FIG. 4 (F) obtained from the triangular wave generation circuit 26 and the current detection waveform of FIG. 4 (B) obtained from the current detection resistor 16,
A combining circuit 29 composed of resistors 27 and 28 is provided, and its output line is connected to the comparator 25. A waveform as shown in principle in FIG. 4 (H) is obtained from the combining circuit 29, and this waveform and the differential output in FIG. 4 (G) are compared by the comparator 25, and the waveform in FIG. When the waveform reaches the level of the differential output, the output of the comparator 25 is changed, and the reset signal forming circuit 33 generates the reset pulse of FIG. 4 (I). This also makes it possible to obtain the same effect as that of the first embodiment.

[Third Embodiment] In the embodiment shown in FIGS. 5 and 6, the current detection line 24 and the triangular wave generating circuit 26 are connected to the comparator 25, and the output terminal of the differential amplifier 22 is the triangular wave generating circuit 26. It is connected to the tilt control terminal. From the triangular wave generation circuit 26, a triangular wave having an opposite slope to the current detection waveform shown in FIG. 6 (B) is output as shown in FIG. 6 (F). As a result, the output of the comparator 25 changes according to the same principle as in FIG.
The reset pulse shown in FIG. 6 (H) is generated at the intersection of the triangular wave shown by the solid line in FIG. 6 (F) and the current detection waveform shown by the dotted line, and the control pulse shown in FIG.
Given to 15.

The duty control based on the change of the output voltage is achieved by controlling the slope of the triangular wave. If the output voltage rises due to a light load after time t _{1 in} FIG. 6, the slope of the triangular wave becomes gentle, the width of the control pulse shown in FIG. 6 (I) becomes narrow, and the output voltage becomes the reference value. Will be returned to the value.

According to the third embodiment, it is possible to obtain the same effects as those of the first embodiment.

[Fourth Embodiment] A DC power supply device according to a fourth embodiment shown in FIG. 7 is obtained by adding a circuit for changing the inclination of a triangular wave according to an input voltage to the circuit of FIG. That is, the capacitor 42 is connected via the diode 41 between the point A of the output line 11 of the rectifier circuit 8 and the ground, and the resistors 43 and 44 are connected in parallel to the capacitor 42.
Is provided and the divided voltage output is applied to the triangular wave generating circuit 26. Since the capacitor 42 smoothes the full-wave rectified waveform, the average value of the AC voltage is obtained, and thus the inclination of the triangular wave is controlled as in the third embodiment. According to the fourth embodiment, in addition to the same operational effect as the first embodiment, the effect of reducing the fluctuation of the input current waveform and the power factor due to the fluctuation of the input voltage can be obtained.

[Modification]

The present invention is not limited to the above-mentioned embodiments, and the following modifications are possible, for example.

(1) As shown in FIG. 8, even when the triangular wave and the current detection waveform are combined and input to the comparator 25, the inclination of the triangular wave is controlled by the average value of the input voltage as in the case of FIG. Good. That is, the triangular wave inclination control circuit shown in FIG. 7 may be added to the circuit shown in FIG.

(2) As shown in FIG. 9, the slope of the triangular wave may be controlled by both the output of the differential amplifier 22 and the average value of the input voltage. That is, the triangular wave inclination control circuit of FIG. 7 may be added to the circuit of FIG.

(3) As shown in FIG. 10, the reactor 13 may be connected to the AC input line of the rectifier circuit 8.

(4) As shown in FIG. 11, instead of the reactor 13,
A transformer primary winding 13a and a secondary winding 13b are provided, and the primary winding
A switching element 15 may be connected in series to 13a so that the energy stored in the transformer is released by the secondary winding 13b.

(5) As shown in FIG. 12, the switching element 15 may be connected in series to the line 11 and the reactor 13 may be connected between the lines 11 and 12.

(6) As shown in FIG. 13, the transformer primary winding 13a as an inductance element and the secondary winding 13b may be insulated and separated.

(7) As shown in FIG. 14, a smoothing circuit including a diode 51 and a reactor 52 may be provided at the output stage of the secondary winding 13b as an inductance element, in addition to the diode 14. The voltage conversion circuit using the switching element 15 can be modified in various ways.

(8) If the output voltage is low, the voltage detection line 20 may be directly connected to the output terminal 9 by omitting the voltage dividing circuit of the resistors 17 and 18.

〔The invention's effect〕

As is apparent from the above, according to the invention of any of the claims, the input current waveform and the power factor can be improved without using the multiplier.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing a DC power supply device according to a first embodiment of the present invention, FIG. 2 is a waveform diagram showing the states of points A to J in FIG. 1, and FIG. 3 is a diagram showing the second embodiment. FIG. 4 is a circuit diagram showing the DC power supply device, FIG. 4 is a waveform diagram showing the states of points A to J of FIG. 3, FIG. 5 is a circuit diagram showing the DC power supply device of the third embodiment, and FIG. 5 is a waveform diagram showing the states of points A to I, FIG. 7 is a circuit diagram showing the DC power supply device of the fourth embodiment, FIG. 8, FIG. 9, FIG. 10, FIG. FIG. 13, FIG. 13 and FIG. 14 are circuit diagrams respectively showing a part of a DC power supply device of a modified example. 1, 2 ... Power supply terminal, 8 ... Rectifier circuit, 9, 10 ... Output terminal, 13 ... Reactor, 15 ... Switching element, 16
...... Capacitor, 19 ...... Current detection circuit, 21 ...... Switching element control circuit, 22 ...... Differential amplifier, 23 ...... Reference voltage source, 25 ...... Comparator, 26 ...... Triangle wave generation circuit.

Claims (6)

[Claims] 1. An AC power supply terminal, a rectifier circuit connected to the AC power supply terminal, in series with an AC power supply line between the AC power supply terminal and the rectifier circuit, or in series with a DC output line of the rectifier circuit. And / or an inductance circuit element connected in parallel, and arranged on the output side of the rectifier circuit to perform on / off operation with a cycle shorter than the cycle of the AC voltage of the AC power supply terminal, and the inductance A DC power supply device comprising: a switching element for controlling energy storage and release for a circuit element; and a smoothing capacitor provided on the output side of the switching element, wherein a DC output voltage smoothed by the smoothing capacitor is detected. And a voltage detector circuit for detecting a current flowing through the switching element or the reactor, A voltage source, a difference signal forming circuit that forms a voltage corresponding to the difference between the reference voltage of the reference voltage source and the detection voltage obtained from the voltage detection circuit, and is sufficiently higher than the AC voltage of the AC power supply terminal. A triangular wave generating circuit that generates a triangular wave at a frequency; a combining circuit that forms a combined voltage of the output voltage of the difference signal forming circuit and the triangular wave; and a current detection waveform obtained from the current detector and the combining circuit. A voltage comparator that generates a voltage comparison output with the synthesized voltage, a set signal generation circuit that generates a set signal in synchronization with the triangular wave, and the voltage comparator that indicates that the current detection waveform has reached the synthesized voltage. A reset signal generating circuit that generates a reset signal in synchronization with the output of the set signal, and a set state in response to the set signal obtained from the set signal generating circuit. A flip-flop circuit that is in a reset state in response to the reset signal obtained from the reset signal generating circuit, and that provides an output pulse indicating the set state to a control terminal of the switching element as an ON control pulse of the switching element, A DC power supply device characterized by being provided. 2. The DC power supply device according to claim 1, further comprising a circuit for controlling the inclination of the triangular wave based on the average value of the AC voltage. 3. An AC power supply terminal, a rectifier circuit connected to the AC power supply terminal, in series with an AC power supply line between the AC power supply terminal and the rectifier circuit, or in series with a DC output line of the rectifier circuit. And / or an inductance circuit element connected in parallel, and arranged on the output side of the rectifier circuit to perform on / off operation with a cycle shorter than the cycle of the AC voltage of the AC power supply terminal, and the inductance A DC power supply device comprising: a switching element for controlling energy storage and release for a circuit element; and a smoothing capacitor provided on the output side of the switching element, wherein a DC output voltage smoothed by the smoothing capacitor is detected. And a voltage detector circuit for detecting a current flowing through the switching element or the reactor, A voltage source, a difference signal forming circuit that forms a voltage corresponding to the difference between the reference voltage of the reference voltage source and the detection voltage obtained from the voltage detection circuit, and is sufficiently higher than the AC voltage of the AC power supply terminal. A triangular wave generating circuit that generates a triangular wave at a frequency; a combining circuit that forms a combined voltage of the current detection waveform obtained from the current detector and the triangular wave obtained from the triangular wave generating circuit; and a difference signal forming circuit A voltage comparator that generates a voltage comparison output between the obtained difference signal and the combined voltage obtained from the combining circuit, a set signal generation circuit that generates a set signal in synchronization with the triangular wave, and the combined voltage is the difference. A reset signal generating circuit that generates a reset signal in synchronization with the output of the voltage comparator indicating that the signal has been reached; To the set state in response to the reset signal, and to the reset state in response to the reset signal obtained from the reset signal generation circuit, the output pulse indicating the set state as an ON control pulse of the switching element of the switching element. A DC power supply device comprising a flip-flop circuit provided to a control terminal. 4. The DC power supply device according to claim 3, further comprising a circuit for controlling the slope of the triangular wave based on the average value of the AC voltage. 5. An AC power supply terminal, a rectifier circuit connected to the AC power supply terminal, in series with an AC power supply line between the AC power supply terminal and the rectifier circuit, or in series with a DC output line of the rectifier circuit. And / or an inductance circuit element connected in parallel, and arranged on the output side of the rectifier circuit to perform on / off operation with a cycle shorter than the cycle of the AC voltage of the AC power supply terminal, and the inductance A DC power supply device comprising: a switching element for controlling energy storage and release for a circuit element; and a smoothing capacitor provided on the output side of the switching element, wherein a DC output voltage smoothed by the smoothing capacitor is detected. And a voltage detector circuit for detecting a current flowing through the switching element or the reactor, A voltage source, a difference signal forming circuit that forms a voltage corresponding to the difference between the reference voltage of the reference voltage source and the detection voltage obtained from the voltage detection circuit, and is sufficiently higher than the AC voltage of the AC power supply terminal. A triangular wave generating circuit for generating a triangular wave at a frequency, the triangular wave generating circuit being formed so that the slope of the triangular wave changes in response to the output of the difference signal forming circuit, the triangular wave obtained from the triangular wave generating circuit, and A voltage comparator that generates a voltage comparison output with a current detection waveform obtained from a current detector, a set signal generation circuit that generates a set signal in synchronization with the triangular wave, and the current detection waveform reaches the triangular wave. And a reset signal generation circuit that generates a reset signal in synchronization with the output of the voltage comparator, and that responds to the set signal obtained from the set signal generation circuit. Then, it becomes a set state, becomes a reset state in response to the reset signal obtained from the reset signal generation circuit, and gives an output pulse indicating the set state to the control terminal of the switching element as an ON control pulse of the switching element. A DC power supply device comprising a flip-flop circuit. 6. The DC power supply device according to claim 5, further comprising a circuit for controlling the slope of the triangular wave based on the average value of the AC voltage.