JP3635515B2 - Power circuit - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a power supply circuit, and more specifically to an AC stabilized power supply circuit and an uninterruptible power supply circuit that have been improved in power factor.
[0002]
[Prior art]
A conventional power factor improvement type stabilized power supply circuit in which one of an AC input line and an output line is coupled as a common line is shown in FIG. 7 previously proposed by the present applicant (Japanese Patent Laid-Open No. 7-245955). )
In FIG. 7, when an AC voltage is input from the AC power supply 10, the voltage is rectified by the half-wave voltage doubler rectifier circuit 21, and a DC voltage substantially equal to the positive side and the negative side with respect to the common line 16 is obtained.
[0003]
The rectified positive and negative DC voltages are respectively switched by step-up chopper circuit / power factor improving filters 31 and 32, and the input current waveform is changed to a sine wave similar to the input voltage waveform to improve the input power factor. In addition, DC voltages boosted in the positive and negative directions can be obtained.
[0004]
The boosted DC voltage is converted into an AC voltage by the DC-AC inverter 37, and further, harmonic components are removed through the filter circuit 96 and the like, and an AC output having a predetermined voltage and frequency is obtained.
[0005]
Here, when an AC voltage is not input due to a power failure or the like, the DC voltage from the batteries 38 a and 38 b is switched and boosted by the boost chopper circuit / power factor improving filters 31 and 32, respectively. The harmonic components are further removed through the filter circuit 96 and the like, and an AC output having a predetermined voltage and frequency is obtained.
[0006]
As described above, in the case of the stabilized power supply device in which one of the AC input lines is the common line 16, the direct transmission circuit that connects the input terminal and the output terminal at the time of a power failure can be configured by a single switching means. it can.
The positive side and negative side batteries 38a and 38b are charged by a charging circuit (not shown) at the time of AC input.
[0007]
In the reference numerals other than the above in FIG. 7, 1 is a direct transmission line, 2 and 3 are AC input terminals, 8 and 9 are AC output terminals, 12 is an output voltage detection circuit, 13 is a load current detection circuit, 14 Is a switching circuit, 15 is an insulating means such as a photocoupler, 17 and 18 are rectifier diodes, 23 and 24 are reactors, 25 and 26 are switching elements, 27 and 28 are rectifier elements, and 29 and 30 are Capacitors 33 and 34 are switching elements, 35 is a reactor, 36 is a capacitor, 39 and 40 are backflow prevention switch elements, 43 and 44 are control circuits, 45 is a pulse width modulation circuit, and 46 and 47 are A current transformer as input current detecting means / insulating means.
[0008]
[Problems to be solved by the invention]
In the conventional circuit, two sets of reactors 23 are provided in order to form two sets of the booster chopper circuit / power factor improving filter 31 on the positive side and the negative booster chopper circuit / power factor improving filter 32 with respect to the common line 16. 24, two sets of switching elements 25 and 26, two sets of rectifier elements 27 and 28, two sets of control circuits 43 and 44, etc., and the positive side boost chopper circuit / power factor improving filter 31 is activated. When the negative side boost chopper circuit / power factor improving filter 32 is inactive, the negative side boost chopper circuit / power factor improving filter 32 is conversely operating when the negative side boost chopper circuit / power factor improving filter 32 is operating. There is a waste in the circuit that the power factor improving filter 31 is at rest, and the price is also expensive.
[0009]
An object of the present invention is to reduce the price and reduce the size of the AC stabilized power supply circuit and uninterruptible power supply circuit with improved power factor by reducing the number of parts and to improve reliability.
[0010]
[Means for Solving the Problems]
In the present invention, on the positive side of the AC power supply 10, the reactor 11, the rectifier diode 51 of the full-wave rectifier circuit 50, the switching element 25, the rectifier diode 53 of the full-wave rectifier circuit 50, the rectifier element 27, and the capacitor 29 The step-up chopper circuit / power factor improving filter 31a is formed, and the detection circuit 19 compares the signal corresponding to the input current from the current transformer 4 as the input current detection / insulation means with the output voltage signal in phase. The switching of the switching element 25 is controlled by a comparator output of the signal and a triangular wave in the control circuit 22.
[0011]
On the negative side of the AC power supply 10, the rectifier diode 52 of the full-wave rectifier circuit 50, the switching element 25, the rectifier diode 54 of the full-wave rectifier circuit 50, the reactor 11, the rectifier element 28, and the capacitor 30 serve as a negative boost chopper circuit. A power factor improving filter 31b is formed, and in the same way as the positive side, a signal corresponding to an input current from the current transformer 4 serving as an input current detecting / insulating means and an output voltage in phase with the detection circuit 20 The signal is compared, and the opening and closing of the switching element 25 is controlled by a comparator output of the signal and the triangular wave in the control circuit 22.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
In the conventional circuit, two sets of booster chopper circuit / power factor improving filters 31 and 32 with respect to the common line 16 are formed, so that two sets of reactors 23 and 24 and two sets of switching elements 25 are formed. 26, two sets of rectifying elements 27 and 28, two sets of control circuits 43 and 44, etc. are necessary, but the basic principle of the present invention is that the reactor 11 is switched by using an AC voltage rectifying element. The element 25, the control circuit 22 and the like are shared in the positive direction and the negative direction, so that the boosting chopper circuit / power factor improving filter 31 can increase the voltage and improve the power factor as in the conventional case. It is a thing.
[0013]
Embodiments of the present invention will be described below with reference to the drawings.
Reference numerals 2 and 3 denote AC input terminals of the AC power supply 10, and reference numerals 8 and 9 denote stabilized AC output terminals. Among these input / output terminals, one AC input terminal 3 and one AC output terminal 9 are directly connected by a common line 16, and the other AC input terminal 2 and the other AC output terminal 8 are directly connected by a direct transmission line 1. And a switching circuit 14 to form a direct transmission circuit.
[0014]
Between the AC input terminals 2 and 3, one current transformer 4 as input current detection / insulation means, and one reactor 11 serving as a positive / negative as a step-up chopper circuit / power factor improvement filter 31 are provided. A series circuit with a full-wave rectifier circuit 50 that is an AC voltage rectifier element is coupled. A step-up chopper circuit / power factor improving filter 31 that also acts as a power factor improving filter excluding an inductance element is coupled to the subsequent stage of the full-wave rectifier circuit 50, and the step-up chopper circuit / power factor improving filter 31 is coupled. In the subsequent stage, a DC-AC inverter 37, a filter circuit 96, and an output voltage detection circuit 12 are sequentially coupled.
[0015]
The step-up chopper circuit / power factor improving filter 31 is composed mainly of a reactor 11 as an inductance element, a full-wave rectifier circuit 50, a switching element 25, rectifier elements 27 and 28, and capacitors 29 and 30.
This step-up chopper circuit / power factor improving filter 31 uses a common element in each of the positive and negative configurations with respect to the common line 16, and the configuration is shown in FIGS. 2 (a) and 2 (b). This will be described in detail.
[0016]
The positive-side step-up chopper circuit / power factor improving filter 31a shown in FIG. 2A includes an inductor 11 as an inductance element, rectifier diodes 51 and 53 of a full-wave rectifier circuit 50, a switching element 25, a rectifier element 27, and a capacitor. 29 is the main component.
The negative-side step-up chopper circuit / power factor improving filter 31b shown in FIG. 2B includes a reactor 11 as an inductance element, rectifier diodes 52 and 54 of a full-wave rectifier circuit 50, a switching element 25, a rectifier element 28, and a capacitor. 30 is the main component.
[0017]
The control circuit 22 of the step-up chopper circuit / power factor improving filter 31 is coupled to the cathode side of the rectifying element 28, and the positive-side detection circuit 19 and the negative-side detection circuit 20 are floating. As described above, one of the secondary coils 6 and the other secondary coil 7 such as the current transformer 4 are coupled to these detection circuits 19 and 20 as the input current detection means, and the primary coil 5 is , Coupled to the AC input terminal 2.
[0018]
The DC-AC inverter 37 is a half bridge type composed of switching elements 33 and 34 and capacitors 29 and 30. The capacitors 29 and 30 are shared with the components of the step-up chopper circuit / power factor improving filter 31. The reactor 35 and the capacitor 36 subsequent to the DC-AC inverter 37 constitute a filter circuit 96 that compresses harmonic components of the generated AC voltage.
[0019]
In series with the input side of the reactor 11 and the source side of the switching element 25, a series circuit of a battery 38 and a backflow prevention switch element 39 is coupled. The battery 38 is for supplying power during a power failure of the commercial power source, and the reverse current blocking switch element 39 is for preventing the battery 38 from being discharged when the AC input voltage drops every commercial half cycle. is there.
The control circuit 22 that opens and closes at a high frequency of 20 kHz or more is directly coupled to the gate of the switching element 25 of the boost chopper circuit / power factor improving filter 31.
[0020]
The gates of the switching elements 33 and 34 of the DC-AC inverter 37 are coupled to a pulse width modulation circuit 45 that opens and closes at 20 kHz or more and performs pulse width modulation corresponding to the AC output voltage waveform.
A load current detection circuit 13 is coupled to the switching circuit 14 of the direct transmission circuit.
[0021]
In FIG. 1, the battery 38 that supplies power at the time of the power failure is connected to the front stage of the switching element 25 via the reactor 11 and the full-wave rectifier circuit 50. However, the present invention is not limited to this, as shown in FIG. The series circuit of the battery 38, the backflow prevention switch element 39 and the reactor 41 may be directly coupled in parallel with the switching element 25 without the reactor 11 and the full-wave rectifier circuit 50 interposed therebetween. In such a circuit configuration, the voltage of the battery 38 is boosted at the time of a power failure of the commercial power supply, and thus the reactor 41 is increased as a component. However, since the power from the battery 38 does not intervene the reactor 11 and the full-wave rectifier circuit 50, the efficiency is improved. improves.
[0022]
Since the boost chopper circuit / power factor improving filter 31 basically has the same operation on the positive side and the negative side, the case of the positive side will be described in more detail with reference to FIG.
In order for the boost chopper circuit / power factor improving filter 31 to function as a power factor improving active filter, in addition to the reactor 11, the switching element 25, and the rectifying element 27, a detection circuit 19 mainly including a non-inverting error amplifier 42. And the control circuit 22 including the general-purpose PWM control IC 48, and the input voltage waveform and the effective input voltage are not used among the four individual inputs of the input voltage waveform, the effective input voltage, the input current waveform, and the output voltage. Thus, the control is performed only by the input current waveform and the output voltage.
[0023]
In FIG. 4, voltage dividing resistors 55 and 56 are coupled between both ends of the capacitor 29, and a capacitor 67 for aligning the phase in parallel with the resistor 56 is inserted. An input current detection resistor 59 is inserted in parallel with one secondary coil 6 of the current transformer 4, and one end of the resistor 59 is coupled to the − input terminal of the non-inverting error amplifier 42 via the resistor 58. ing.
The reference voltage Vref is coupled to the negative input terminal of the non-inverting error amplifier 42 through the resistor 57 and further coupled to the output terminal through the resistor 60.
Reference numeral 70 denotes a photocoupler for insulating and coupling between the control circuit 22 and the detection circuit 19, and reference numeral 71 denotes a photocoupler for insulatingly coupling between the control circuit 22 and the detection circuit 20.
[0024]
The effect | action by the above structures is demonstrated.
First, as shown in FIG. 2A, when the positive side of the AC power supply 10 is input, half-wave rectification is performed by the rectifier diode 51 and the rectifier diode 53 of the full-wave rectifier circuit 50, as shown in FIG. A half-wave rectified voltage is obtained. This is boosted and chopped by the boosting chopper circuit / power factor improving filter 31 to generate a ripple voltage as shown in FIG.
[0025]
Similarly, on the negative side, as shown in FIG. 2B, a half-wave rectification is performed by the rectifier diode 52 and the rectifier diode 54 of the full-wave rectifier circuit 50, and a voltage that is boosted and chopped is obtained.
These positive and negative voltages are converted into an alternating current by the DC-AC inverter 37, the high frequency component is removed by the filter circuit 96, and an alternating voltage is supplied to the load.
[0026]
Next, the power factor improving action will be described.
In order to make the output voltage constant and make the input current similar to the input voltage, the input of the non-inverting error amplifier 42 in the detection circuit 19 (and the detection circuit 20) in FIG. In order to use it as a reference for detection, a reference voltage Vref is applied through a resistor 57. Further, an output voltage signal is applied to the + input terminal of the non-inverting error amplifier 42. Prior to error amplification of these signals by the non-inverting error amplifier 42, the phases must be matched with each other. Otherwise, even if the output voltage becomes constant, the input current of the power factor correction circuit does not have a waveform similar to the input voltage.
[0027]
Therefore, in order to match the phases of the input signals of the non-inverting error amplifier 42 with the + input terminal and the − input terminal, and to make the input current have a waveform similar to the input voltage, A minute signal that is inverted with respect to the input voltage is injected. Specifically, the current transformer 4 serving as the input current detection means / insulation means is insulated from the step-up chopper circuit / power factor improvement filter 31 and flows through the resistor 59 which has been transformed to a specific turn ratio (FIG. 5). When the voltage Ro · i generated by the current shown in h) is used for injection, the input voltage V (−) at the −input terminal of the non-inverting error amplifier 42 becomes the reference voltage Vref as shown in FIG. And a small signal that is inverted with respect to the input voltage.
V (−) = Vref− {resistance 57 / (resistance 57 + resistance 58)} × (Vref + Ro · i)
[0028]
Further, as the input voltage V (+) at the + input terminal of the non-inverting error amplifier 42, the following signal obtained by dividing the output voltage by the resistors 55 and 56 is input.
V (+) = {resistor 56 / (resistor 55 + resistor 56)} × output voltage Vo
[0029]
In the signal as it is, the phases of the voltages at the + input terminal and the − input terminal of the non-inverting error amplifier 42 do not coincide with each other. Therefore, a capacitor 67 is coupled in parallel with the resistor 56, and the voltage change is delayed by the charging time constant of the resistor 56 and the capacitor 67 as shown in FIG. The input voltage at the input terminal is the same phase as the input voltage at the negative input terminal. Specifically, the capacitance of the capacitor 67 is adjusted so that the phase of the input voltage at the negative input terminal of the non-inverting error amplifier 42 is delayed by 3π / 4.
[0030]
If the error is amplified by the non-inverting error amplifier 42 in this state, the amplification degree is too high. Therefore, the output of the non-inverting error amplifier 42 is set as shown in FIG.
The signal of FIG. 5E of the non-inverting error amplifier 42 is insulated by a photocoupler 70 as an insulating means and sent to the [8] terminal of the PWM control IC 48 in the control circuit 22. In this PWM control IC 48, the signal sent to the [8] terminal and the triangular wave signal of FIG. 5 (f) of the oscillator are compared by a comparator, and an output as shown in FIG. 5 (g) is obtained. It is done.
[0031]
This signal is output from the [2] terminal of the PWM control IC 48 and becomes the gate signal of the switching element 25 as it is, so that the step-up chopper circuit / power factor improving filter 31 operates.
In this way, the PWM control IC 48 can be used to control only the input current waveform and the output voltage. Further, the boosted chopper circuit / power factor improving filter 31 boosts the common line 16 to the positive side and the negative side, respectively, and the stabilized DC voltage is sent to the DC-AC inverter 37 in the subsequent stage.
[0032]
The switching elements 33 and 34 of the half-bridge type DC-AC inverter 37 are alternately opened and closed at a high frequency by the pulse width modulation signal from the pulse width modulation circuit 45, and the opening and closing time width corresponds to the AC output voltage waveform. By performing the pulse width modulation, a pulse voltage waveform such as the solid line waveform of FIG. A high-frequency component is removed from the pulse voltage by a filter circuit 96 including a reactor 35 and a capacitor 36, and an AC output having a predetermined voltage and frequency as shown by a dotted line waveform in FIG.
[0033]
The overcurrent protection circuit of the power factor correction circuit according to the present invention detects a circuit current by inserting a resistor 49 in series with the source side of the switching element 25, and detects the circuit current at the [15] terminal of the general-purpose PWM control IC 48. By injecting, the pulse-by-pulse overcurrent protection circuit built in the general-purpose PWM control IC 48 can be used as it is.
[0034]
In the above embodiment, the switching elements 25, 33 and 34 are not limited to MOSFETs, but may be bipolar transistors or other switching elements.
The input current detection / insulation unit 4 is not limited to a current transformer, and may be a Hall element.
[0035]
【The invention's effect】
Since the present invention shares the basic components in the positive and negative directions of the step-up chopper circuit / power factor improving filter 31, a power factor improving active filter can be obtained with about half the circuit configuration of the conventional circuit.
[0036]
Because the general-purpose PWM control IC 48 used in switching power supplies is also used to control the power factor improvement active filter, there is no significant increase in the number of parts, and the number of parts in the conventional circuit can be greatly reduced, resulting in lower prices. It is possible to reduce the size and improve the reliability.
[0037]
When AC power is not input due to a power failure or other accident, the reverse current blocking switch element 39 such as a thyristor is turned on, and the DC voltage from each of the positive and negative batteries 38 is used for boosting chopper circuit and power factor improvement. An uninterruptible power supply that can be switched by the filter 31, boosted to the positive side and the negative side, converted to an AC voltage, and further removed high frequency components by the filter circuit 96 to obtain an AC output of a predetermined voltage and frequency. It becomes a device.
[Brief description of the drawings]
FIG. 1 is an electric circuit diagram showing a first embodiment of a power supply circuit according to the present invention.
FIG. 2A is an electric circuit diagram of the boost chopper circuit when the AC input voltage is on the positive side, and FIG. 2B is an electric circuit diagram of the boost chopper circuit when the AC input voltage is on the negative side.
FIG. 3 is an electric circuit diagram showing a second embodiment of the power supply circuit according to the present invention.
FIG. 4 is a detailed electric circuit diagram of a control circuit 22 and detection circuits 19 and 20 inside a power supply circuit according to the present invention.
FIG. 5 is an operation waveform diagram during half-wave rectification of the power supply circuit according to the present invention.
FIG. 6 is an operation waveform diagram during full-wave rectification of the power supply circuit according to the present invention.
FIG. 7 is an electric circuit diagram of a conventional power supply circuit.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Direct transmission line, 2, 3 ... AC input terminal, 4 ... Current transformer, 5 ... Primary coil, 6, 7 ... Secondary coil, 8, 9 ... AC output terminal, 10 ... AC power supply, 11 ... Reactor, 12 DESCRIPTION OF SYMBOLS ... Output voltage detection circuit, 13 ... Load current detection circuit, 14 ... Switching circuit, 15 ... Insulating means such as photocoupler, 16 ... Common line, 17, 18 ... Diode, 19, 20 ... Detection circuit, 21 ... Half-wave voltage doubler Rectifier circuit, 22 ... control circuit, 23, 24 ... reactor, 25, 26 ... switching element, 27, 28 ... rectifier element, 29, 30 ... capacitor, 31, 32 ... boost chopper circuit / power factor improving filter, 33, 34 ... Switching element, 35 ... Reactor, 36 ... Capacitor, 37 ... DC-AC inverter, 38 ... Battery, 39, 40 ... Backflow prevention switch element, 41 ... Reactor, 2 ... Non-inverting error amplifier, 43, 44 ... Control circuit, 45 ... Pulse width modulation circuit, 46, 47 ... Current transformer, 48 ... IC for PWM control, 49 ... Resistance, 50 ... Full wave rectification circuit, 51, 52, 53, 54 ... Rectifier diode, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65 ... Resistor, 66, 67, 68, 69 ... Capacitor, 70, 71 ... Photocoupler, 96 ... Filter circuit.

Claims (3)

The AC input terminals 2, 3 and the AC output terminals 8, 9 are coupled to one terminal 3, 9 to form a common line 16. In a power supply circuit in which a full-wave rectifier circuit 50 for rectifying positive and negative directions and a boost chopper circuit / power factor improving filter 31 are coupled, and a DC-AC inverter 37 is coupled to the subsequent stage. The step-up chopper circuit / power factor improving filter 31 connects the full-wave rectifier circuit 50 between the AC input terminals 2 and 3 via the reactor 11, and the positive and negative outputs of the full-wave rectifier circuit 50 are positively connected. In order to connect the switching element 25 having a common direction and a negative direction, connect the anode side of the rectifying element 27 to the positive output side of the full-wave rectifier circuit 50, and obtain a positive voltage on the cathode side of the rectifying element 27. One end of the capacitor 29 is connected, the other end of the capacitor 29 is connected to the one AC input terminal 3, the cathode side of the rectifying element 28 is connected to the negative output side of the full-wave rectifying circuit 50, and the rectifying element 28 is connected. One side of a capacitor 30 for obtaining a negative voltage is connected to the anode side of the first side, and the other side of the capacitor 30 is connected to the one AC input terminal 3. This boost chopper circuit / power factor improving filter 31 The DC voltage in the positive direction and the negative direction is obtained by using the full-wave rectifier circuit 50 and the switching element 25 which are common to the positive and negative, and then converted into AC again by the DC-AC inverter 37 and output. A power circuit characterized by. Between the negative side of the input side and the full-wave rectifier circuit 50 of the re Akutoru 11, inserts the series circuit of the reverse-blocking switching element 39 and the battery 38, and turns on the reverse-blocking switching element 39 during a power failure of the AC power supply 10 the power supply circuit according to claim 1 Symbol mounting is characterized in that so as to supply DC voltage from the battery 38 Te. In parallel with the switching element 25, the reactor 41, by inserting a serial circuit of reverse-blocking switching element 39 and the battery 38, and turns on the reverse-blocking switching element 39 during a power failure of the AC power supply 10 to supply a DC voltage from the battery 38 the power supply circuit according to claim 1 Symbol mounting, characterized in that the.

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