JP2002369530A - Diode rectifying circuit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a diode rectifying circuit for generating a sine wave AC input current and reducing the generation of harmonics current of AC power supply frequency only with passive elements of simplified circuit structure, without using high-frequency switching elements. SOLUTION: Reduction of power factor in electric power system can be prevented by respectively connecting in parallel capacitors to diodes in the positive output side in a three-phase diode bridge circuit, inserting an inductance to form a resonance circuit which resonates in the AC power supply frequency between each power supply input terminal of the three-phase diode bridge circuit and a three-phase AC power supply, generating a resonance current by these capacitor and inductance to each power supply input terminal, reducing generation of harmonics current by generating a sine wave current at each power supply terminal, despite the rectifying operation of diode, and also reducing waveform distortion of the power system due to the diode rectifying circuit.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a diode rectifier circuit that reduces the generation of harmonic currents at the frequency of an input AC power supply.

[0002]

2. Description of the Related Art Diode rectification circuits that obtain DC power from an AC power supply are used in various electric and electronic devices. However, diode rectification circuits generate harmonic currents in a power system as a power source. And the power factor is reduced. This harmonic current is generated due to the rectifying action of the diode as the rectifying element. In other words, the current flowing through the diode flows only in a phase range narrower than 360 degrees, which is the entire phase range of the AC power supply waveform (sine wave). This is because a current is generated.

For this reason, switching power supplies have been used which reduce the generation of harmonic current by converting the AC input current into a sine wave. The switching power supply switches the AC voltage (or AC current) at a frequency much higher than the frequency of the AC power supply (for example, several tens kHz to several hundreds kHz, hereinafter referred to as “high frequency”), and then rectifies the switching power supply, thereby obtaining the switching power supply. The AC input current can be approximately sinusoidal.

[0004]

However, the switching power supply uses a high-frequency switching element such as a transistor, the circuit for driving the high-frequency switching element is complicated, and the cost is increased due to the complexity of the circuit. Can not deny. In addition, there is a problem that loss occurs in a transistor or the like which is a high-frequency switching element due to switching, and noise of a switching frequency and its harmonic (hereinafter, “switching noise”) occurs.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problem. Diode rectification is achieved at low cost and without switching noise by using only passive elements having a simple circuit structure without using high-frequency switching elements. It is an object of the present invention to provide a diode rectifier circuit in which an AC input current of a circuit is converted into a sine wave to reduce generation of a harmonic current (hereinafter, “harmonic current”) of an input AC power supply frequency.

[0006]

According to the present invention, in order to attain the above object, according to the present invention, there are provided first to sixth diodes which are connected to a three-phase AC power supply to obtain a rectified output thereof. A three-phase diode bridge circuit, first to third capacitors respectively connected in parallel to the first to third diodes on the positive polarity output side in the three-phase diode bridge circuit, and each of the three-phase diode bridge circuits A first circuit which is interposed in series between a power input terminal and the three-phase AC power supply to form a resonance circuit having a frequency equal to the frequency of the three-phase AC power supply between the first to third capacitors; To a third inductance.

In the diode rectifier circuit having such a configuration, since each capacitor and each inductance resonate at the frequency of the three-phase AC power supply, each power supply input terminal of the three-phase diode bridge circuit despite the rectification of the diode. , A sine wave current of the power supply frequency flows, thereby reducing the generation of harmonic current. Therefore, the waveform distortion of the power system is reduced, and the power factor is prevented from lowering.

According to the second aspect, the first to third positive output terminals are provided.
Since the resonance capacitors are connected not only to the diode but also to the fourth to sixth diodes on the negative polarity output side, the symmetry of the three-phase diode bridge circuit is improved, and the generation of even-order harmonic currents is further increased. Reduced. The capacitors connected in parallel to the diodes on the positive output side and the negative output side also operate as smoothing capacitors, so that the smoothing circuit can be omitted.

According to a third aspect of the present invention, the AC input of the three-phase diode bridge circuit is inserted in series between each of the power input terminals of the three-phase diode bridge circuit and the first to third inductances. First to third phase control
By controlling the conduction angles of the first to third switching elements, the rectified output (DC output) voltage of the diode rectifier circuit can be controlled, and the first to third switching elements can be controlled. By controlling the switching element in the cutoff state, the diode rectifier circuit can be protected.

According to a fourth aspect of the present invention, there is provided a single-phase diode bridge circuit comprising first to fourth diodes and connected to a single-phase AC power supply to obtain a rectified output of the single-phase AC power supply. First and second capacitors connected in parallel to first and second diodes, respectively, and serially interposed between the power input terminals of the single-phase diode bridge circuit and the single-phase AC power, respectively. And a first and a second inductance forming a resonance circuit having a frequency equal to the frequency of the single-phase AC power supply with the first and second capacitors.

In the diode rectifier circuit having such a configuration, since each capacitor and each inductance resonate at the frequency of the single-phase AC power supply, each power supply input terminal of the single-phase diode bridge circuit despite the rectification action of the diode. , A sine-wave current flows, so that generation of harmonic current is reduced. Therefore, the waveform distortion of the power system is reduced, and the power factor is prevented from lowering.

According to a fifth aspect of the present invention, a resonance capacitor is connected not only to the first and second diodes on the positive output side but also to the third and fourth diodes on the negative output side. The symmetry of the circuit is improved, and the generation of even harmonic currents is further reduced. Further, since the capacitors connected in parallel to the diodes on the positive output side and the negative output side also operate as smoothing capacitors, the smoothing circuit can be omitted.

According to the present invention, the AC input of the single-phase diode bridge circuit is inserted in series between each of the power input terminals of the single-phase diode bridge circuit and the first and second inductances. It has first and second switching elements for controlling the phase.
By controlling the conduction angle of the second switching element and the rectification output voltage of the diode rectification circuit, the diode rectification circuit can be controlled by controlling the first and second switching elements to a cutoff state. Can be protected.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a diode rectifier circuit according to an embodiment of the present invention will be described with reference to the drawings. FIG.
1 is a configuration diagram illustrating a first embodiment of a diode rectifier circuit according to the present invention, which is a diode rectifier circuit that obtains DC power from a three-phase AC power supply. The three-phase diode bridge circuit of the diode rectifier circuit 10 includes first to third diodes D1 to D3 on the positive output side and a fourth diode D1 on the negative output side.
To sixth diodes D4 to D6. Capacitors C1, C2, C3 are connected in parallel to the diodes D1, D2, D3 on the positive output side, respectively.

A U-phase power supply Ug of a three-phase AC power supply consisting of a U-phase, a V-phase, and a W-phase, and a first power supply of a three-phase diode bridge circuit.
A first inductance L1 is inserted in series between the power input terminal 1 (the anode of the first diode and the cathode of the fourth diode), and the V-phase power supply Vg and the second power input End 2 (the anode of the second diode and the fifth
A second inductance L2 is interposed between the W-phase power supply Wg and the third power supply input terminal 3 (the anode of the third diode and the cathode of the sixth diode). Is provided with a third inductance L3.

The three-phase diode bridge circuit has a positive output terminal connected to the output terminal OUT1, and a negative output terminal connected to the output terminal OUT2. When the output terminal OUT2 is grounded, the rectified output voltage of the diode rectifier circuit 10 becomes a positive voltage. Note that the rectified output voltage of the diode rectifier circuit 10 is smoothed by a smoothing circuit including, for example, an inductance Lf and a capacitor Cf, and is supplied to a load resistor RL.

In the diode rectifier circuit 10 configured as described above, the respective phase currents iu, i flowing through the power input terminals 1, 2, 3 by the respective phase power supplies Ug, Vg, Wg.
v and iw are converted into sinusoidal waves despite the rectification of the diodes D1 to D6. For the sinusoidal conversion of this current, U
The phase will be described as an example. FIG. 2 shows a current flowing through a first power supply input terminal 1, diodes D1, D4 and a capacitor C1 of a three-phase diode bridge circuit by a U-phase power supply Ug;
FIG. 4 is a waveform diagram for explaining a power supply waveform of a three-phase AC power supply. FIG. 3 is a diagram for explaining a U-phase current iu by the U-phase power supply Ug. Here, each phase power supply Ug, V
g and Wg output voltages (hereinafter, “U-phase voltage, V-phase voltage,
W-phase voltage ") Let eu, ev, ew be eu = Em × sin ωt ev = Em × sin (ωt−2π / 3) ew = Em × sin (ωt−4π / 3) Note that Em is the maximum value of each phase voltage, the unit of angle is radian, ω is the angular frequency of the three-phase AC power supply, and t is time.

As shown in FIG. 2, the U-phase voltage eu is negative,
The phase voltage ev is positive, the W-phase voltage ew is positive, and the time when the U-phase voltage eu has a substantially negative maximum value is time t0. Therefore, as shown in FIG. 3A, the diode D4 conducts and a current id4 flows from the negative output side. The forward voltage drop Vf of the diode D4 is assumed to be approximately 0 volt.

On the other hand, the diode D1 is cut off, and the capacitor C1 has the absolute value of the current Ic from the positive output side.
c (hereinafter, the current Ic represents the absolute value of the current ic) flows as a charging current, and the capacitor C1 is charged with the terminal connected to the positive output side as a positive voltage. Therefore, the current id4 and the current ic become the U-phase current iu flowing from the power input terminal 1 to the U-phase power supply Ug via the inductance L1, and the absolute value Iu of the U-phase current iu (hereinafter, U-phase current Iu is U (It represents the absolute value of the phase current iu), and Iu = id4 + Ic (1). In order to clarify the direction in which the current flows, the U-phase current iu and the current ic of the capacitor C1 are represented by absolute values. Further, the absolute value voltage of the U-phase voltage eu is referred to as voltage Eu. Hereinafter, the current and the like expressed in absolute values are for clarifying the direction and the like in which the current flows.

The charging voltage of the capacitor C1 is represented by a voltage Vc.
And Before time t0, the capacitor C
1 is already in a charged state, but after time t0, the capacitor C1 is further charged by the current Ic, and the voltage Vc rises to its maximum value. Thereafter, when the U-phase voltage eu becomes positive, the current Ic changes from the charge current of the capacitor to the discharge current as shown in FIG. At this time, the U-phase current Iu
Is Iu = Ic-id4 (2).

When the current Ic changes from the charging current to the discharging current (this time is referred to as tc), the V-phase voltage ev becomes lower than the U-phase voltage eu as shown in FIG. The diode D to which the V-phase voltage ev is applied.
5 eventually conducts and the current i flowing through the diode D4
d4 flows to the diode D5, and the diode D4 is cut off. The time when the diode D4 cuts off in this way is t1, and at this time, the voltage between the anode and the cathode of the diode D4 becomes the reverse voltage. Assuming that the reverse voltage is Vr, Vr is negative.

Thus, during the period from time t0 to time t1, a resonance current that resonates at the power supply frequency flows through the resonance circuit constituted by the inductance L1 and the capacitor C1 (hereinafter, the resonance circuit that resonates at the power supply frequency is referred to as “resonance circuit”). Resonant circuit "). After the time t1, as described above, the diode D4 is turned off and the current Ic has already become the discharge current of the voltage Vc of the capacitor C1. Here, during the period until the capacitor C1 is completely discharged, FIG.
As shown in (c), the diode D1 connected in parallel with the capacitor C1 has a positive voltage on the cathode side and is cut off. Therefore, during this period, the U-phase current Iu and the current Ic
And Iu = Ic (3). Eventually, when the capacitor C1 is completely discharged, the diode D1 becomes conductive and a current id1 flows. The time at which the diode D1 conducts in this way is t2.

On the other hand, during the period from time t1 to time t2, the reverse voltage Vr of the diode D4 is
As the voltage Vc decreases due to the discharge of 1, the voltage gradually increases from 0V. Thus, the period from time t1 to time t2,
A resonance current flows through a resonance circuit including the inductance L1 and the capacitor C1.

As described above, when the capacitor C1 is completely discharged and the current id1 flows through the diode D1 (at time t2).
), The voltage Vc (the same voltage as the forward voltage drop Vf of the diode D1) becomes substantially 0 volt. At this time, the U-phase current Iu is equal to the absolute value Id1 of the current (hereinafter, the current Id1 represents the absolute value of the U-phase current id1), and Iu = Id1 (4). The current iu (current id1) is output to the output terminal OUT1.
To the load. Eventually, the polarity of the U-phase current iu is inverted, and this inversion time is set to time t3.

As described above, from time t2 to time t3, the inductance L1 does not form a resonance circuit with the capacitor C1. However, in the diode rectifier circuit 10, as shown in FIG. 4, the inductance L2 and the capacitor C2 act as a resonance circuit in the V phase, and the inductance L3 and the capacitor C3 act as a resonance circuit in the W phase. (Current flowing from the input power supply terminals 2 and 3) flows to the power supply input terminal 1 via the inductance L1.

Thus, during the period from time t2 to time t3, a resonance current flows through the inductance L1. FIG. 4 omits illustration of the blocking diode and shows only the conducting diode. Also, since the diode 1 is conducting, the capacitor C1 does not act as a capacitor, and is not shown.

At time t3, the polarity of the U-phase current iu is inverted and the diode D1 is cut off.
Since the diode D4 is not conducting yet, the current ic (charging) flows through the capacitor C1 toward the power supply input terminal 1, and the voltage Vc increases. This current becomes the U-phase current iu. Therefore, during this period, the U-phase current Iu and the current Ic
And Iu = Ic (5).

On the other hand, the reverse voltage Vr is applied to the diode D4 after time t1, but the output terminal OUT
Assuming that the rectified output voltage generated at 1 and OUT2 is V10, V10 = Vc + Vr. Here, the rectified output voltage V10 is a U-phase voltage eu,
The power input terminal 1 is set by the V-phase voltage ev and the W-phase voltage ew.
2 are output as voltages having the highest absolute values of the instantaneous voltages generated in .about.2. Therefore, the rectified output voltage V10 is U
Not only the phase voltage eu but also the V-phase voltage ev and the W-phase voltage ew
Is the voltage linked (related) to

Then, the reverse voltage Vr blocking the diode D4 also rises temporarily by linking to the V-phase voltage ev and the W-phase voltage ew, but eventually rises in the voltage Vc and drops in the rectified output voltage V10. Accordingly, the reverse voltage Vr of the diode D4 drops to 0 volt, the polarity of the anode-cathode voltage of the diode D4 is reversed, and the diode D4 becomes conductive. The time at which the diode D4 conducts is time t4. At this time, the capacitor C1 has the current ic
Is still charged.

Thus, during the period from time t3 to time t4, a resonance current flows through the resonance circuit of the inductance L1 and the capacitor C1. Here, the operation state of the diode rectifier circuit 10 at the time t4 is the same as the operation state of the diode rectifier circuit 10 at the time t0, and the capacitor C1 is already in the charged state at the time t0 as described above. Thus, diode rectifier circuit 10 repeats the above-described operation in the period from time t0 to time t4.

FIG. 2 shows the continuous operation of the diode rectifier circuit 10 described above for each period. The current ic in FIG.
At time t0, the current is negative (the current ic flows from the positive output to the power input terminal 1), but changes to positive before reaching time t1. This corresponds to FIGS. 3A and 3B. In FIG. 2, a period from time t0 to time t1,
A substantially rectangular wave current is superimposed on the current ic. During the same period, when the diode D4 conducts and the current id4 flows, and when the current ic charges the capacitor C1, the current id4 becomes the current ic. Reduce the absolute value of the current ic
Becomes the discharge current of the capacitor C1, the current i
d4 is for increasing the absolute value of the current ic. Then, as described above, the current ic continues to flow as the discharge current until time t2, stops flowing during the period from time t2 to time t3, and flows again as the charging current of the capacitor C1 from time t3 to time t4.

With respect to the currents id4 and id1 shown in FIG. 2, the current id4 having a substantially rectangular waveform flows through the diode D4 from time t0 to time t1 as described above. During this period, the resonance current flows through the inductance L1 and the capacitor C1, and the resonance current does not flow through the diode D4, so that the current id4 has a substantially rectangular wave. As described above, during the period from time t2 to time t3, the current from the V-phase / W-phase resonance circuit flows through the diode D1, and the waveform of the current id1 becomes a partial sine waveform. From time t1 to time t2 and from time t3 to time t4, both diodes D1 and D4 are shut off as described above.

Voltage Vc in FIG. 2 (voltage of capacitor C1)
Shows a state where the battery is charged with the above-mentioned current ic. The voltage Vc is charged with the current ic from the time t3, and when the polarity of the current ic is reversed, the voltage Vc starts to be discharged and is completely discharged at the time t2 as described above. The reverse voltage Vr in FIG. 2 indicates a reverse voltage of the diode D4 generated by linking the V-phase voltage ev and the W-phase voltage ew. During a period from time t1 to time t4, the diode D4 is shut off.

During the period from time t0 to time t1, the U-phase current i
When u flows out of the power supply input terminal 1, as described above, the relationship of Iu = id4 + Ic is established, and the current waveform of the sum of the current ic and the current id4 in FIG.
It becomes a substantially sine wave by the resonance circuit of 1 and the capacitor C1. Then, when the direction of the U-phase current iu is reversed, the relationship of Iu = Ic-id4 is established as described in the equation (2) as described above.
The current waveform obtained by subtracting the current id4 from the current ic becomes a substantially sine wave by the resonance circuit.

Similarly, from time t1 to time t2, FIG.
From the current ic and the above equation (3), Iu = Ic, the time t2
From time t3 to time t3, the current id1 of FIG.
From Iu = Id1, from the time t3 to the time t4, the U-phase current i is obtained from the current ic of FIG. 2 and the above equation (5), Iu = Ic.
u becomes a substantially sine wave by the resonance circuit. Thus, the U-phase current iu flowing from the U-phase power supply Ug is converted into a sine wave by the resonance circuit from time t0 to t4 (over one cycle of the three-phase AC power supply).

Similarly, V-phase current iv flowing from V-phase power supply Vg and W-phase current i flowing from W-phase power supply Wg
w is also converted into a sine wave by the resonance circuit. In the above-described diode rectifier circuit 10, when the harmonic current of the U-phase current iu of the three-phase AC power supply was actually measured, the harmonic current was improved and a slight (about 3%) even-order harmonic current was reduced. It was only included. FIG. 6A shows the waveform of the U-phase current iu. FIG. 6B shows a rectified output voltage V10 of the diode rectifier circuit 10.

FIG. 5 is a block diagram showing a second embodiment of the diode rectifier circuit according to the present invention, which is a diode rectifier circuit for obtaining DC power from a three-phase AC power supply. This diode rectifier circuit 20 is intended to further improve even-order harmonic currents compared to the diode rectifier circuit of the first embodiment. Components having the same functions as those of the first embodiment are denoted by the same reference numerals and illustrated.
The description is omitted.

The diode rectifier circuit 20 is different from the diode rectifier circuit 10 in that the diode D4 has a capacitor C
4, a capacitor C5 is connected to the diode D5, and a capacitor C6 is connected to the diode D6 in parallel. These capacitors form a resonance circuit with the inductances L1 to L3 like the capacitors C1 to C3. In the above-described diode rectifier circuit 10, since the capacitors C1 to C3 are connected in parallel to the diodes D1 to D3 on the positive output side, a circuit configuration in which the positive output side and the negative output side of the three-phase diode bridge circuit are asymmetric. As a result, an even harmonic current was slightly contained (about 3%). In the diode rectifier circuit 20, the symmetry of the circuit is improved by the above-described configuration.

When the harmonic current of the U-phase current iu was actually measured in the diode rectification circuit 20, the even-order harmonic current contained in the diode rectification circuit 10 by about 3% was reduced to almost no longer contained. FIG. 7A shows the waveform of the U-phase current iu. FIG. 7B shows a rectified output voltage V20 of the diode rectifier circuit 20. Here, since the capacitors C4 to C6 are connected in parallel to the diodes D4 to D6 on the negative polarity output side, the capacitors C1 and C6 are connected in parallel.
4. The capacitors C2 and C5 and the capacitors C3 and C6 are connected in series, respectively, and the capacitors connected in series are connected in parallel, and function as a smoothing capacitor between the output terminals OUT1 and OUT2. Accordingly, the rectified output voltage V20 of the diode rectifier circuit 20 has a more smoothed voltage waveform than the rectified output voltage V10 of the diode rectifier circuit 10 (FIG. 6B) as shown in FIG. 7B. I have.

As described above, the diode rectifier circuit of the second embodiment can omit the smoothing circuit including the inductance Lf and the capacitor Cf of the first embodiment. FIG. 8 is a configuration diagram showing a third embodiment of the diode rectifier circuit according to the present invention, which is a diode rectifier circuit that obtains DC power from a three-phase AC power supply. Note that components having the same functions as those of the first embodiment are denoted by the same reference numerals, and description thereof is omitted.

As shown in FIG. 8, the diode rectifier circuit 30 further includes a triac D
31 to D33 (switching elements) are added.
The triac D31 is connected in series with the inductance L1, and is interposed between the U-phase power supply Vg and the power supply input terminal 1. The triac D32 is also connected in series with the inductance L2, and the triac D33 is also connected in series with the inductance L3.

The diode rectifier circuit 30 converts the AC input current into a sine wave similarly to the diode rectifier circuit 10, and the triac control circuit 34 controls the triac D3.
The phase of the gates of 1 to D33 is controlled via control lines 34a to 34c, so that the U-phase current iu, the V-phase current iv, and the W-phase current i
Controls the conduction angle of w. The rectified output voltage V30 of the diode rectifier circuit 30 is controlled by the phase control of the conduction angle. Also, the diode rectifier circuit 30 and the load resistance RL
If a failure occurs in the triacs D31 to D3, the conduction angle of the U-phase current iu to the W-phase current iw is set to zero.
3 also functions as a protection circuit.

It goes without saying that the insertion of the triacs D31 to D33 can be performed in the rectifier circuit 20 in the same manner. FIG. 9 is a configuration diagram showing a fourth embodiment of the diode rectifier circuit according to the present invention, which is a diode rectifier circuit 40 that obtains DC power from a single-phase AC power supply. The single-phase diode bridge circuit of the diode rectifier circuit 40 includes diodes D1 and D2 on the positive output side and diodes D3 and D4 on the negative output side.
1 and C2 are connected in parallel.

The single-phase AC power supply E has its one end Ea connected to the first power supply input terminal 1 (the anode of the first diode and the cathode of the third diode) of the single-phase diode bridge circuit via the first inductance L1. And the other end Eb is connected to the second power input terminal 2 (the anode of the second diode and the cathode of the fourth diode) via the second inductance L2. The rectified output voltage of the diode rectifier circuit 40 is smoothed by a smoothing circuit including an inductance Lf and a capacitor Cf and supplied to a load resistor RL.

In the diode rectifier circuit 40 configured as described above, the current flowing into the power supply input terminal 1 becomes the resonance current of the single-phase AC power supply E by the resonance circuit of the inductance L1 and the capacitor C1. The flowing current becomes a similar resonance current by the resonance circuit of the inductance L2 and the capacitor C2. Thus, the diode rectifier circuit 40 can make the current flowing into the power input terminals 1 and 2 into a sine wave, thereby reducing the generation of harmonic current.

FIG. 10 is a block diagram showing a fifth embodiment of the diode rectifier circuit according to the present invention, which is a diode rectifier circuit 50 for obtaining DC power from a single-phase AC power supply.
Note that components having the same functions as in the fourth embodiment are denoted by the same reference numerals, and description thereof is omitted. This diode rectifier circuit 50 is different from the above-described diode rectifier circuit 40 in that parallel capacitors C3 and C4 are further connected in parallel to the diodes D3 and D4 on the negative polarity output side, respectively.
1 and C2, a resonance circuit is formed with the inductances L1 and L2.

In the diode rectifier circuit 50 thus configured, the single-phase diode bridge circuit has a symmetrical circuit configuration, and further reduces the generation of even-order harmonic currents as in the second embodiment. Can be. Further, since the capacitors C3 and C4 are connected in parallel to the diodes D3 and D4 on the negative output side, the capacitors C1 to C4 act as smoothing capacitors. Therefore, the smoothing circuit including the inductance Lf and the capacitor Cf in the fourth embodiment is used. Can be omitted.

FIG. 11 is a block diagram showing a sixth embodiment of the diode rectifier circuit according to the present invention, which is a diode rectifier circuit 70 for obtaining DC power from a single-phase AC power supply.
Note that components having the same functions as in the fourth embodiment are denoted by the same reference numerals, and description thereof is omitted. The diode rectifier circuit 70, as shown in FIG.
Further, triacs D71 and D72 are added to the diode rectifier circuit 40. The triac D71 is inserted between the inductance L1 and the power input terminal 1. The triac D72 is also interposed between the inductance L2 and the power input terminal 2.

The diode rectifier circuit 70 is similar to the diode rectifier circuit 40 in that the current flowing into the power supply input terminals 1 and 2 is converted into a sine wave, and the triac control circuit 7
Reference numeral 4 controls the phase of the gates of the triacs D71 and D72 via the control lines 74a and 74b to control the conduction angle of the input current of the diode rectifier circuit 70. The rectified output voltage V70 of the diode rectifier circuit 70 is controlled by the phase control of the conduction angle. The diode rectifier circuit 70
When a failure occurs in the load RL or the load resistance RL, the conduction angle of the input current of the diode rectifier circuit 70 is set to zero, so that the triacs D71 and D72 are connected to the diode rectifier circuit 70.
Acts as a protection circuit.

A triac D7 for controlling the conduction angle
Needless to say, the insertion of 1 and D72 can be similarly performed in the diode rectifier circuit 50. Note that the resonance frequency of the resonance circuit in the present invention does not need to exactly match the frequency of the AC power supply, and does not deviate from the purpose of reducing the generation of harmonic current by converting the AC input current of the diode rectifier circuit into a sine wave. In, there is no problem that there is an error.

The present invention is not limited to the above-described embodiment, but is connected in parallel to the inductance inserted between the power supply input terminal of the diode bridge rectifier circuit and the power supply and the diode of the diode bridge rectifier circuit. And a capacitor, a resonance circuit can be formed, and the present invention can be implemented without departing from the purpose of converting the AC input current of the diode rectifier circuit into a sine wave.

[0052]

As described above, according to the diode rectifier circuit of the present invention, a diode is used without using a high-frequency switching element and only with a passive element having a simple circuit configuration, and therefore, at low cost and without generating switching noise. The AC input current of the rectifier circuit is converted into a sine wave to reduce the generation of harmonic currents, reduce the distortion of the voltage and current waveforms of the power supply system that supplies AC power to the diode rectifier circuit, and reduce the power factor of the power supply system. The effect of not lowering is exhibited.

Further, by connecting the capacitors constituting the resonance circuit to the positive output side and the negative output side of the diode bridge circuit, the effect that the smoothing inductance and the smoothing capacitor of the smoothing circuit can be omitted can be exhibited.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a diode rectifier circuit (three-phase alternating current) of a first embodiment of a diode rectifier circuit according to the present invention.

FIG. 2 is a waveform diagram illustrating operating voltages and currents of the diode rectifier circuit according to the first embodiment.

FIG. 3 shows a U of the diode rectifier circuit according to the first embodiment.
FIG. 9 is an operation diagram showing a state of rectification of a phase voltage eu and a change of a U-phase current iu.

FIG. 4 is a configuration diagram showing a configuration of a resonance circuit in a state of FIG. 3 (c).

FIG. 5 is a configuration diagram of a diode rectifier circuit (three-phase alternating current) according to a second embodiment of the diode rectifier circuit according to the present invention.

FIG. 6 shows the U of the diode rectifier circuit according to the first embodiment.
FIG. 9 is a waveform chart showing waveforms of a phase current iu and a rectified output voltage V10.

FIG. 7 illustrates a diode rectifier circuit according to a second embodiment.
FIG. 7 is a waveform diagram showing waveforms of a phase current iu and a rectified output voltage V20.

FIG. 8 is a configuration diagram of a diode rectifier circuit (three-phase alternating current) according to a third embodiment of the diode rectifier circuit according to the present invention.

FIG. 9 is a configuration diagram of a diode rectifier circuit (single-phase AC) according to a fourth embodiment of the diode rectifier circuit according to the present invention.

FIG. 10 is a configuration diagram of a diode rectifier circuit (single-phase AC) according to a fifth embodiment of the diode rectifier circuit according to the present invention.

FIG. 11 is a configuration diagram of a diode rectifier circuit (single-phase AC) according to a sixth embodiment of the diode rectifier circuit according to the present invention.

[Explanation of symbols]

 1, 2, 3 Power input terminals C1 to C6 Capacitors D1 to D6 Diodes D31 to D33, D71, D72 Triacs L1 to L3 Inductance E Single-phase power supply Ug U-phase power supply (three-phase AC power supply) Vg U-phase power supply (three-phase AC power supply) Power supply) Wg W-phase power supply (Three-phase AC power supply)

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Kazumasa Otsuka 614 140 Ishitani, Gifu-shi, Gifu Prefecture (72) Inventor Isamu 58 Exit, Nagashimacho, Kuwana-gun, Mie Pref. 5993 Ichidamura Induction Heat Refining Co., Ltd. F term (reference) 5H006 AA02 CA07 CB01 CC02

Claims (6)

[Claims] 1. A three-phase diode bridge circuit comprising first to sixth diodes, connected to a three-phase AC power supply to obtain a rectified output thereof, and a first to third positive-polarity output terminals in the three-phase diode bridge circuit. A first to a third capacitor respectively connected in parallel to a third diode; and a third capacitor interposed in series between each power input terminal of the three-phase diode bridge circuit and the three-phase AC power supply. A diode rectifier circuit comprising: first to third inductances forming a resonance circuit having a frequency equal to the frequency of the three-phase AC power supply between the first and third capacitors. 2. The diode rectifier circuit according to claim 1, further comprising: a fourth to a sixth capacitor connected in parallel to the fourth to sixth diodes on the negative output side of the three-phase diode bridge circuit. A diode rectifier circuit comprising: 3. The diode rectifier circuit according to claim 1, wherein each of the three-phase diode bridge circuits is inserted in series between each of the power input terminals and the first to third inductances, A diode rectifier circuit comprising: first to third switching elements for controlling a phase of an AC input of the three-phase diode bridge circuit. 4. A single-phase diode bridge circuit, comprising first to fourth diodes, connected to a single-phase AC power supply to obtain a rectified output thereof, and a first and a positive output side of the single-phase diode bridge circuit. A first and a second capacitor respectively connected in parallel to a second diode; and the first and second capacitors respectively inserted in series between the power input terminals of the single-phase diode bridge circuit and the single-phase AC power, respectively. A diode rectifier circuit, comprising: first and second inductances forming a resonance circuit having a frequency equal to the frequency of the single-phase AC power supply between the first and second capacitors. 5. The diode rectifier circuit according to claim 4, further comprising third and fourth capacitors connected in parallel to the third and fourth diodes on the negative output side of the single-phase diode bridge circuit, respectively. A diode rectifier circuit comprising: 6. The diode rectifier circuit according to claim 4, wherein each of the power supply input terminals of the single-phase diode bridge circuit and the first and second inductances are inserted in series, respectively. A diode rectifier circuit comprising: a first and a second switching element for controlling a phase of an AC input of the single-phase diode bridge circuit.