JP3169504B2 - DC power supply - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a DC power supply provided with a single-phase full-wave rectifier comprising a diode.

[0002]

2. Description of the Related Art On the one hand, there is a tendency to use DC electronic equipment which operates using DC as a power supply, and on the other hand, with the development of control technology, frequency control is performed via a DC power supply and an inverter, or an inverter is controlled. There is a tendency that AC devices whose speed is controlled via a device and an AC motor are frequently used. Reflecting such a trend, recently, a demand for a noiseless DC power supply device having good high-frequency suppressing means has become severe.

[0003] In order to meet this kind of demand, the following filter system has been conventionally proposed. (1) A so-called active filter system in which the current of a rectifier bridge circuit is made to follow a full-wave rectified waveform of an AC voltage at high speed by a boost chopper switching circuit, and a high-frequency ripple current due to switching is removed by a low-pass filter. (2) An LC system in which a reactor is inserted in series with the main current circuit and a small-capacity capacitor is connected to the shunt, thereby increasing the conduction angle and compensating for phase delay.

[0004]

The above-mentioned active filter system (1) has the following disadvantages 1 to 3 particularly in applications of high power. 1. Control rectifier with current capacity corresponding to high current at high speed,
Since a rectifier diode and a reactor are required, there are many problems in terms of element size, reliability, cost, and the like. 2. Since the built-in size is large and the switching current is large, the generated switching noise adversely affects other circuits. 3. Since the amount of current ripple is set according to the maximum current, the ripple content increases at low loads, and the input current waveform is distorted. Further, it is necessary to use a large LC constant.

The above-mentioned LC system (2) has the following disadvantages. 1. Since the rise of the current for each half wave becomes steep,
Higher harmonic noise increases instead. 2. In general, the harmonic reduction effect is small, and in many cases, the target level cannot be reached.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a DC power supply having a filter means free from the above-mentioned disadvantages. More specifically, an object of the present invention is to provide a DC power supply device that can be configured in a small size, does not adversely affect other circuits, and can efficiently suppress harmonics.

[0007]

According to the first aspect of the present invention, a die is provided.
A single-phase full-wave rectifier rectifier consisting of an
And a capacitor connected in series.
A first parallel circuit connected in parallel between the
And a diode connected in series to form a first parallel circuit.
A series circuit connected in series with the DC main current circuit on the load side
And a capacitor in parallel with the load on the load side of the series circuit.
And a second parallel circuit connected to the rear of the series circuit.
And the values of the capacitors and the capacitors of the second parallel circuit,
At the time of rated current approximately 89% of the half-wave period in the series circuit at the time of rated load
The flow is set to continue until the following, and the first parallel circuit is reset.
Actuator inductance and capacitor capacity
The period of the natural vibration that occurs corresponding to the product of the
The voltage is set to be in the range of about 64-92% of the half-wave time of the voltage.
And the value of the capacitor of the second parallel circuit is
The positive peak value of the current of one parallel circuit flows through the series circuit
Set so that it is in the range of about 40 to 70% of the peak value of the current.
The gist of the invention is a defined DC power supply.

[0008]

[0009]

[0010]

[0011]

According to the first aspect of the present invention, a first parallel circuit having a reactor and a capacitor connected in series is connected between the DC output terminals of the rectifier, and the reactor and the diode are connected in series with the DC main current circuit of the rectifier. The connected serial circuit is connected, and a second parallel circuit including a capacitor is connected in parallel with the load on the load side of the series circuit. This makes it possible to compensate for and improve the current delay and the current peak of the choke input type filter circuit which does not include the second parallel circuit by the charge / discharge current of the first parallel circuit. By adjusting the compensation current, low-order harmonic components of the input current to the filter circuit can be significantly reduced.

[0012]

[0013]

FIG. 1 shows an embodiment of a DC power supply according to the present invention .

The DC power supply shown in FIG. 1 includes a full-wave rectifier 20 to which AC power is input from an AC power supply 10 having a frequency of 50 Hz, for example, via a power supply line impedance 11 composed of a resistor 12 and an inductance 13. I have. Rectifier 20 comprises four sets of bridged diodes. On the output side of the rectifier 20, the first parallel circuit 30, the series circuit 40, and the second
A filter circuit connected to the mold is connected, and a load 60 is connected to the output side. The first parallel circuit 30 has a reactor 31 and a capacitor 32 connected in series, and is directly connected between the DC output terminals of the rectifier 20. The series circuit 40 includes a series connection of a reactor 41 and a diode 42 having a forward polarity, and is connected in series to a DC output main current circuit of the rectifier 20. The second parallel circuit 50 includes a capacitor 51, and is connected to the load 60 of the series circuit 40 in parallel with the load 60. The load 60 can be, for example, an inverter device and an AC motor cascaded thereto.

In the DC power supply shown in FIG. 1, what is connected between the rectifier 20 and the load 60 is a filter circuit. In this filter circuit, the potential at the connection point between the first parallel circuit 30 and the series circuit 40, that is, the DC potential of the rectifier 30, is set as the potential of the negative DC output terminal (that is, the anode side) of the rectifier 20 as the reference potential (0 V). The output voltage is Va, the voltage at the connection point between the reactor 41 and the diode 42 is Vd, the voltage on the load side of the diode 42, that is, the voltage at the capacitor 51, is Vo, the voltage at the connection point between the reactor 31 and the capacitor 32, that is, the voltage at the capacitor 32 is Vp, 20 is the AC input voltage to Vi, rectifier 2
The DC output current of 0, that is, the input current to the filter circuit is Ia, the charging current of the first parallel circuit 30 is Ip, and the current of the series circuit 40 is Im. The polarity of each current is
The direction from the positive electrode toward the negative electrode is defined as positive.

The operation of the apparatus shown in FIG. 1 will be schematically described with reference to FIG. AC power supply 10
Of the capacitor 3 of the first parallel circuit 30 during each half-wave period of
2, the charging from the rectifier 20 side and the series circuit 40
One charge / discharge is performed with one cycle of discharge to the side. Here, the reactor 3 in the first parallel circuit 30
By appropriately adjusting the inductance L31 of 1 and the capacitance C32 of the capacitor 32, if the voltage Vp of the capacitor 32 is discharged to near zero V, the charging current (-Ip), that is, the rise of the input current Ia to the filter circuit is accelerated. can do.

On the other hand, the parallel circuit 50 includes a capacitor 51
The charging current starts flowing when the input voltage Vd from the series circuit 40 exceeds the charging voltage Vo (Vd> Vo), and the discharge current (-Ip) of the parallel circuit 30 already described merges as a charging current halfway. I do. Thus, the parallel circuit 3
0 and the input current I to the filter circuit corresponding to the sum (Ip + Im) of the current Im of the series circuit 40.
In the charging cycle of the capacitor 51, a current corresponding to the sum of the charging current of the parallel circuit 50 and the rising current of the parallel circuit 30 flows. In the discharging cycle of the capacitor 51, the charging current of the parallel circuit 30 A current obtained by subtracting the discharge current flows.

As a result, the current delay and the current peak in the conventional "choke input type" filter circuit without the parallel circuit 30 can be compensated and improved by the charge / discharge current of the parallel circuit 30. In this case, by adjusting the compensation amount, the low-order harmonic components of the input current Ia to the filter circuit can be significantly reduced.

Next, the first parallel circuit 30 will be described with reference to the voltage and current waveforms of each part during the AC voltage half-wave period shown in FIG.
The behavior of the current and voltage of the series circuit 40 will be described in detail. It should be noted that, for convenience when referring to Table 1 below, numbers will be added and described in order. First, the behavior of the series circuit 40 will be described. (1) In the state of Va <Vo at the beginning of the AC half-wave period, no current in the positive direction can flow through the series circuit 40, and the current in the negative direction is blocked by the diode 42, so that Im = 0. (2) When the voltage Va rises and becomes Va> Vo, Va−Vd> 0, and the current Im starts to flow through the series circuit 40 using this difference voltage as a drive source, and the value Im gradually increases. (3) The voltage Im changes from rising to falling after the peak, and the current Im becomes maximum when Va = Vo again. Thereafter, even after Va <Vo, the current Im continues to flow while Im (0) is being used while the reactor 41 (accumulated energy) is used as a drive source and decreases. (4) When Im = −Ip while the current Im decreases, the current supply from the rectifier 20 is zero (Ia = 0).
And the decreasing gradient of the voltage Va changes. (5) At the time when Im = 0, the effect of the diode 42 prevents Im <0 from being achieved, the current Im no longer changes, and Va = Vd, returning to the initial state.

The capacitor 51 has a sufficiently large capacitance with respect to the inductance of the reactor 41, and the voltage Vo is expressed by the difference between the average value of the current Im (substantially equal to the DC output current) and the instantaneous value of the current Im. Since it only slightly moves up and down and does not significantly affect the operation described here, this shall be ignored.

Next, the behavior of the parallel circuit 30 will be described. (1) At the beginning of the AC half-wave period, the current Ip flowing at the end of the previous half-wave continues to flow while decreasing. The voltage Va is negative due to the previous half-wave current Ia (= Ip) and the line inductance. During this time, the current I
p changes from negative to positive (the capacitor 32 changes from discharging to charging). (2) When the AC power supply voltage Vi rises and Va-Vp> 0 as Vi> Vp, the current Ip (charging current) changes to a gradually increasing state using this difference voltage as a drive source. (3) The voltage Vp rapidly rises due to the charging action of the current Ip and catches up with the voltage Va. When Vp = Va again, the current Ip becomes maximum, and the reactor 31 is driven even if Va <Vp thereafter. As a source, the current Ip continues to flow while decreasing. (4) When the current Ip decreases and Ip = 0, Vp−Va becomes maximum, and thereafter, Vp−Va
, The current Ip changes to negative polarity (discharge polarity) and its absolute value continues to increase. (5) When the current Ip becomes the discharge polarity of the capacitor 32, the voltage Vp rapidly drops, and when Vp = Va again, the absolute value of the current Ip becomes the negative maximum value, and the reactor 31 and the capacitor 32 Current Ip
Continues to flow, decreasing its absolute value. (6) When Im = −Ip, the output current I of the rectifier 20
a (= Im + Ip) also becomes zero. Since the current Ia cannot be negative due to the action of the rectifier 20, Ia = 0, Ia
With Im = -Ip, the currents Im and Ip are simultaneously zero.
During the period of Ia = 0, the voltage Va is independent of the power supply voltage Vi,
The voltages Vp and Vd are obtained by the voltage dividing operation of the reactors 31 and 41.
(DIm / dt = −dIp / d)
t). (7) After Im = Ip = 0, the effect of the diode 42 does not make Im <0. On the other hand, the voltage Vp has a minimum value close to zero V, and the difference voltage Va−Vp
, The current Ip changes to Ip = Ia> 0, and the voltage Vp also starts to increase. (8) When the voltage Va decreases and the voltage Vp increases, V
a = Vp, and Va <V
Vp, and the current Ip decreases. In this state, Va = 0
, And the half-wave period ends to return to the initial state.

The filter circuit including the parallel circuits 30, 50 and the series circuit 40 provided on the output side of the rectifier 20 repeats exactly the same operation after the next half wave. All that changes is the polarity of the voltage and current at the input of the rectifier 20. Due to the polarity change of the current and the power supply inductance 13, Va <0 in the initial half-wave period (the period of "1" in Table 1 below).

The behavior of the currents Im (current of the series circuit 40), Ip (current of the first parallel circuit 30), and Ia (output current of the rectifier 20 = input current of the filter circuit) during both positive and negative half-wave periods. 6 is shown in FIG. 6, and the current state is shown in Table 1 by increasing (↑), decreasing (↓), and maintaining the same value (→), classified by the numbers in parentheses.

[0024]

[Table 1] As described above, the current Ia is (current of the circuit 30) → (current of the circuit 40 + current of the circuit 30) → (current of the circuit 40−
(Current of the circuit 30).

Thus, the capacitor 32 of the parallel circuit 30
Is deep, the current rises quickly, the conduction angle of the input current is widened, and the current waveform is small (one circuit) → large (2
Since the sum changes from circuit sum) to small (difference between the two circuits), it is possible to construct a DC power supply device that is close to a sine wave, has low harmonic current, and has a high input power factor.

In setting the values of the reactor 31 and the capacitor 32 of the parallel circuit 30, the reactor 41 of the series circuit 40, and the reactor 51 of the parallel circuit 50 in the DC power supply shown in FIG . Without relying on the power supply from the first parallel circuit 30, the reactor 41 of the series circuit 40 is energized as a drive source so that the current continues to flow until about 89% of the half-wave period, and (b) The inductance L31 of the reactor 31 of the parallel circuit 30 and the capacitance C of the capacitor 32
The period of the natural oscillation corresponding to the product of (L31 · C32) is in the range of about 64 to 92% of the half-wave time of the AC input voltage Vi , and (c) the first parallel circuit 30 Is approximately 40 to the peak value of the current Im flowing through the series circuit 40.
By being in the range of 70%, the eye of the present invention
The target can be achieved satisfactorily .

First, condition (a) is satisfied. By satisfying this condition, the conduction angle of current Ia can be increased.
The main part of the current Ia in the latter half of the half cycle period is the series circuit 40.
And the current Ip of the first parallel circuit 30. When the current Im is interrupted, the current Ia is also interrupted. If the conduction angle of the current Ia is shorter than the conduction angle in this range, the target effect cannot be achieved.

Next, the reason for the condition (b) is as follows.
This is for keeping the cycle of the charge pump within a half cycle of the power supply. The positive peak and the negative peak of the current Ip of the parallel circuit 30 fall between １ ／ and ／ of the half cycle period, that is, the period of the natural oscillation is 2 半 of the half wave time.
The starting point is a constant setting such as / 3. When the period is short, harmonic currents due to the natural vibration are likely to occur, but when the period is long, there is little problem because the interaction with the current Im of the series circuit 40 forcibly synchronizes within a half cycle period. It is easier to achieve the target effect if you set it to.

The reason for the condition (c) is that the current Ia approaches a sinusoidal waveform. Since the peak of the current Ip of the parallel circuit 30 has substantially the same value on the positive side and the negative side and is generated at timings of 1/3 and 2/3 of the half cycle, respectively, the current value is adjusted by adjusting this current value. The symmetry of Ip can be adjusted to approximate a sine waveform.

The peaks of the current Im of the series circuit 40 and the current Ip of the parallel circuit 30 do not always coincide with each other, and even if the symmetry is visually improved, the harmonics do not always decrease in total. Therefore, fine adjustment by simulation or actual operation test is required.

A specific example in which the constants are set based on the above concept and the power supply harmonics of the DC power supply of 2.5 kW correspond to the regulation value proposed in Europe will be described below.

AC power supply: 230 V, 50 Hz Power supply line impedance: (0.4 + j0.25) Ω (There is no clear setting in the proposed regulation value) Proposed regulation value (for class A, only odd-numbered orders): order harmonics (Rms (A)) peak value conversion 3 2.30 3.253 5 1.14 1.612 7 0.77 1.089 9 0.40 0.566 11 0.33 0.467 13 0.21 0. 297 15 0.15 0.212 17 (0.15 * 15 / n) (0.212 * 15 / n): Next, a specific example of each constant will be described (see FIGS. 5 and 6). (1) Assuming that the DC output voltage is 250 V, the average DC output current is 10 A as a rated current, the discharge time of the series circuit current within a half-wave period is 7 ms, and the allowable ripple voltage is 15 V, the capacitance C51 of the capacitor 51 is approximately C51. = 10 × 7 × 10 ⁻³ /15=4.7×10 ⁻³ (F) = 4700 (μF)

(2) C51 = 4700 μF, equivalent resistance R60 of load 60 = 25Ω, AC power supply voltage 230V, 50H
Simulated by incorporating the line impedance as z. When L41 = 6.8mH, the end of energization is about 9.25ms
(Condition a) The current Im has a peak value of about 26.5 A. (3) The simulation is performed with the natural oscillation period determined by L31 and C32 being 75% of the half-wave time (7.5 ms). 2 × π × (L31 · C32) ^1/2 = 7.5 × 10 ^-3 (L31 · C32) = 1.425 × 10 ^-6 where L31 / C32 = 220, that is, L31 = 17.
7 × 10 ⁻³ (H) == 17.7 (mH), C32 = 80.
If 5 × 10 ^-6 (F) = 80.5 (μF), the ratio I
p / Im is about 51%.

FIG. 7 shows the harmonic characteristics of the current Ia corresponding to the characteristic examples shown in FIGS. The characteristic line Ir shows the peak value conversion of the above-mentioned proposed European regulation value, and the characteristic line Ia shows the harmonic characteristics (peak value conversion) of the current Ia in FIGS. It can also be seen from this figure that the harmonic characteristics of the current Ia according to the present invention sufficiently clear the proposed European regulation for each harmonic.

The above setting scheme results in the rectifier 20
Assuming that the output current Ia of FIG. 4 becomes almost the full conduction angle of 180 °, Va = Vi during this period, and the parallel circuit 30 and the series circuit 40 do not affect each other. It is retroactively calculated. If fine adjustment of numerical values, addition of elements, and the like are performed based on the constant obtained in this manner, it is possible to further reduce harmonics and cope with variable loads.

FIG. 8 shows that the end of the current supply by only the first parallel circuit 30 under the condition (a) is about 89.5% (-Q) of the half-wave period by changing the inductance L41 of the reactor 41.
FIG. 7 shows transitions of the currents Ia, Im, and Ip in the case of changing to the point of 8.95 ms) and the case of changing to about 92.5%.
Are shown.

FIG. 9 shows the harmonic characteristics of the current Ia under the conditions of FIG. 8. The characteristic line Ir shows the conversion of the peak value of the proposed European regulation value in the same manner as described above, and the characteristic lines Iau and Iav show the characteristics. 9 shows the harmonic characteristics (converted to peak values) of the corresponding currents Iau and Iav in FIG. 8, respectively. It can also be seen from this figure that the harmonic characteristics of the current Ia clear the proposed European regulation for each harmonic.

FIG. 10 shows that the oscillation cycle of the condition (b) is changed by changing the inductance L31 and the capacitance C32.
Transitions of the currents Ia, Im, and Ip when set to about 6.4 ms (64%), about 9.2 ms (92%), and the middle, with suffixes u, w, and v, respectively. It is.

FIG. 11 shows the harmonic characteristics of the current Ia under the conditions of FIG.
The meaning of w conforms to FIG. Also in this case, it can be seen that the harmonic characteristic of the current Ia satisfies the proposed European regulation for each harmonic.

FIG. 12 shows the current ratio Ip / Im under the condition (c).
, Suffixes u, w, and v, respectively, show changes in currents Ia, Im, and Ip when are changed to about 40%, about 70%, and between them by changing inductance L31 and capacitance C32, respectively. Things.

FIG. 13 shows the harmonic characteristics of the current Ia under the conditions of FIG.
The meaning of w conforms to FIG. Also in this case, it can be seen that the harmonic characteristic of the current Ia satisfies the proposed European regulation for each harmonic.

FIG. 2 shows a modified embodiment of the present invention. The feature of this embodiment is that a diode 33 is connected in parallel to the capacitor 32 of the first parallel circuit 30 in the apparatus of FIG. By doing so, the capacitor 3
Even if the ripple voltage 2 is set to a large value, there is no possibility that a reverse voltage will be applied. Therefore, it is possible to use an electrolytic capacitor in which a large-capacity capacitor can be easily obtained.

Further, the reactor 14 is connected in series to the AC input current circuit of the rectifier 20 as shown in FIG. 3, or the DC output terminal of the rectifier 20 is connected to the first terminal as shown in FIG.
By connecting the reactor 15 in series with the DC output current circuit of the rectifier 20 between the parallel circuit 30 and the parallel circuit 30, the harmonic reduction effect can be further improved, and the present invention can be applied favorably over a wide load range. be able to. In that case, regarding the arrangement position of the reactor, the embodiment of FIG.
4 (the DC output side of the rectifier 20), there is no significant difference in characteristics, but in any case, the current (absolute value) at zero AC voltage is small. There is a need. Advantageous measures may be taken in consideration of effects and costs.

It should be noted that there is no difference in the circuit function even if the mutual positions of the series-connected elements in the electric circuit are interchanged. For example, in the apparatus shown in FIG.
The position of the reactor 31 and the capacitor 3
The position of No. 2 may be exchanged.

[0045]

As described above in detail, according to the present invention, the current delay and current peak of a reactor input type rectifier circuit having a capacitor in parallel with a load are compensated and improved by the charge / discharge current of the capacitor circuit. be able to. Further, by adjusting the compensation current, particularly low-order harmonic components of the input current can be significantly reduced. Therefore, according to the present invention,
It is possible to provide a small DC power supply device capable of efficiently suppressing harmonics without adversely affecting other circuits.

[Brief description of the drawings]

FIG. 1 is a connection diagram showing one embodiment of a DC power supply device according to the present invention.

FIG. 2 is a connection diagram showing another embodiment of the invention of claim 1;

FIG. 3 is a connection diagram showing another embodiment of the invention of claim 1;

FIG. 4 is a connection diagram showing another embodiment of the present invention.

FIG. 5 shows currents and currents at various parts for explaining the operation of the apparatus shown in FIG. 1;
FIG. 7 is a waveform diagram showing the behavior of the voltage for a half cycle.

FIG. 6 is a waveform chart showing the behavior of each section current in the case of a specific setting example in the device of FIG. 1;

FIG. 7 is a harmonic characteristic diagram of a rectifier output current corresponding to the current state in FIG. 6;

FIG. 8 is a waveform diagram of a current of each part showing a state of a change in a current passage width due to a reactor value adjustment of a series circuit in the apparatus of FIG. 1;

FIG. 9 is a diagram showing harmonic characteristics of a rectifier output current corresponding to each current state shown in FIG. 8;

FIG. 10 is a waveform diagram of a current of each part for describing a change in an oscillation cycle due to adjustment of the values of the reactor and the capacitor of the first parallel circuit in the apparatus of FIG. 1;

11 is a diagram showing harmonic characteristics of a rectifier output current corresponding to each current state shown in FIG. 10;

FIG. 12 is a waveform diagram of each part current for explaining a ratio change between a positive peak value of a current of a first parallel circuit and a peak value of a current of a series circuit in the device of FIG. 1;

FIG. 13 is a diagram showing harmonic characteristics of a rectifier output current corresponding to each current state shown in FIG. 12;

[Explanation of symbols]

 Reference Signs List 10 AC power supply 11 Power supply line impedance 20 Full-wave rectifier 30 First parallel circuit 31 Reactor 32 Capacitor 40 Series circuit 41 Reactor 42 Diode 50 Second parallel circuit 51 Capacitor 60 Load

Claims (1)

(57) [Claims] A first parallel circuit comprising a single-phase full-wave rectifier composed of a diode, a reactor and a capacitor connected in series, and connected in parallel between DC output terminals of the rectifier, and a reactor and a diode. A series circuit connected in series and connected in series to the DC main current circuit on the load side of the first parallel circuit; and a second parallel circuit formed of a capacitor and connected in parallel to the load on the load side of the series circuit. And a reactor of the series circuit; and
2 at the rated load
Current flows through the series circuit until about 89% of the half-wave period
Set to continue, the reactor of the first parallel circuit
Of inductance and capacitance of capacitor
The period of the natural vibration corresponding to the product is half of the AC input voltage.
Set to be in the range of about 64-92% of the wave time,
Further, the value of the capacitor of the second parallel circuit is
The positive peak value of the current of the parallel circuit flows through the series circuit.
Between about 40-70% of the peak current
DC power supply set to .