JP4721563B2 - Diode rectifier circuit - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a diode rectifier circuit that reduces the generation of harmonic currents at an input AC power supply frequency.
[0002]
[Prior art]
A diode rectifier circuit that obtains DC power from an AC power supply is used in various electrical and electronic devices, but the diode rectifier circuit generates harmonic current in the power system that is the power source, resulting in waveform distortion of the power system. And reduce its power factor. This harmonic current is generated due to the rectifying action of the diode which is the rectifying element. In other words, since the current flowing through the diode flows only in a phase range narrower than 360 degrees that is the entire phase range of the AC power supply waveform (sine wave), the AC input current of the diode rectifier circuit is not a sine wave, and harmonics This is because current is generated.
[0003]
Therefore, a switching power supply is used that reduces 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 of kHz to several hundred kHz, hereinafter referred to as “high frequency”), and then rectifies the switching power supply. The AC input current can be approximately a sine wave.
[0004]
[Problems to be solved by the invention]
However, the switching power supply uses a high-frequency switching element such as a transistor, and the circuit for driving the high-frequency switching element is complicated. In addition, the cost increase accompanying the complexity of the circuit cannot be denied. Further, there are problems that a loss occurs in a transistor or the like that is a high-frequency switching element with switching, and noise of a switching frequency and its harmonics (hereinafter referred to as “switching noise”) occurs.
[0005]
The present invention has been made in order to solve the above-described problem, and only uses passive elements having a simple circuit configuration without using high-frequency switching elements. Therefore, the AC of the diode rectifier circuit is low in cost and without generating switching noise. An object of the present invention is to provide a diode rectifier circuit in which an input current is converted into a sine wave to reduce generation of harmonic current (hereinafter referred to as “harmonic current”) of an input AC power supply frequency.
[0006]
[Means for Solving the Problems]
In order to achieve the above object, according to the present invention, in claim 1, a three-phase diode bridge circuit comprising first to sixth diodes and connected to a three-phase AC power source to obtain a rectified output thereof, First to third capacitors connected in parallel to first to third diodes on the positive output side in the phase diode bridge circuit, each power input terminal of the three-phase diode bridge circuit, and the three-phase AC power source Between the first to third capacitors and equal to the frequency of the three-phase AC power source. resonance A diode rectifier circuit is provided having first to third inductances forming a resonant circuit of frequency.
[0007]
In the diode rectifier circuit having such a configuration, each capacitor and each inductance resonate at the frequency of the three-phase AC power supply. Therefore, a power source is connected to each power input terminal of the three-phase diode bridge circuit regardless of the rectifying action of the diode. Since a sinusoidal current of frequency flows, the generation of harmonic current is reduced. Therefore, the waveform distortion of the power system is reduced, and the power factor is prevented from lowering.
[0008]
Since the resonance capacitor is connected not only to the first to third diodes on the positive output side but also to the fourth to sixth diodes on the negative output side, the three-phase diode bridge circuit is symmetrical. And the generation of even harmonic currents is further reduced. Further, the capacitor connected in parallel to the diodes on the positive output side and the negative output side also operates as a smoothing capacitor, so that the smoothing circuit can be omitted.
[0009]
According to a third aspect of the present invention, the AC input of the three-phase diode bridge circuit is phase-controlled by being inserted in series between each power input terminal of the three-phase diode bridge circuit and the first to third inductances. The first to third switching elements are provided, and the rectified output (DC output) voltage of the diode rectifier circuit can be controlled by controlling the conduction angle of the first to third switching elements. The diode rectifier circuit can be protected by controlling the first to third switching elements to the cutoff state.
[0010]
According to a fourth aspect of the present invention, there is provided a single-phase diode bridge circuit comprising the first to fourth diodes and connected to a single-phase AC power source to obtain a rectified output thereof, The first and second capacitors respectively connected in parallel to the second diode, and each power supply input terminal of the single-phase diode bridge circuit and the single-phase AC power supply are respectively inserted in series and are connected in series. Equal to the frequency of the single-phase AC power supply between the first and second capacitors resonance A diode rectifier circuit is provided having first and second inductances forming a frequency resonant circuit.
[0011]
In the diode rectifier circuit having such a configuration, each capacitor and each inductance resonate at the frequency of the single-phase AC power supply. Therefore, despite the rectifying action of the diode, each power input terminal of the single-phase diode bridge circuit has a sine. Since the wave current flows, the generation of harmonic current is reduced. Therefore, the waveform distortion of the power system is reduced, and the power factor is prevented from lowering.
[0012]
According to the fifth aspect of the present invention, since the 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 single-phase diode bridge circuit is symmetrical. And the generation of even harmonic currents is further reduced. Further, since the capacitor connected in parallel to the diodes on the positive output side and the negative output side also operates as a smoothing capacitor, the smoothing circuit can be omitted.
[0013]
According to a sixth aspect of the present invention, the AC input of the single-phase diode bridge circuit is phase-controlled by being inserted in series between each power supply input terminal of the single-phase diode bridge circuit and the first and second inductances. The first and second switching elements are provided, and the rectified output voltage of the diode rectifier circuit can be controlled by controlling the conduction angle of the first and second switching elements. The diode rectifier circuit can be protected by controlling the two switching elements to the cut-off state.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
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 block diagram showing 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 source. 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 fourth to sixth diodes D4 to D6 on the negative output side. Capacitors C1, C2, and C3 are connected in parallel to the diodes D1, D2, and D3 on the positive output side, respectively.
[0015]
A U-phase power source Ug of a three-phase AC power source composed of a U-phase, a V-phase, and a W-phase, and a first power input terminal 1 of the three-phase diode bridge circuit (the anode of the first diode and the cathode of the fourth diode) The first inductance L1 is inserted in series between the V-phase power supply Vg and the second power supply input terminal 2 (the anode of the second diode and the cathode of the fifth diode). The second inductance L2 is inserted, and the third inductance L3 is inserted between the W-phase power source Wg and the third power source input terminal 3 (the anode of the third diode and the cathode of the sixth diode). Has been.
[0016]
The positive output side of the three-phase diode bridge circuit is connected to the output terminal OUT1, and the negative output side is 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. 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 supplied to the load resistor RL.
[0017]
In the diode rectifier circuit 10 configured as described above, the phase currents iu, iv, and iw flowing through the power input terminals 1, 2, and 3 by the phase power supplies Ug, Vg, and Wg are rectified by the diodes D1 to D6. Despite the action, it is sine waved. This current sine wave generation will be described by taking the U phase as an example.
FIG. 2 is a waveform diagram for explaining the current flowing through the first power input 1 of the three-phase diode bridge circuit, the diodes D1 and D4 and the capacitor C1 and the power waveform of the three-phase AC power source by the U-phase power source Ug. is there. FIG. 3 is a diagram for explaining the U-phase current iu from the U-phase power supply Ug. Here, each output voltage of each phase power supply Ug, Vg, Wg (hereinafter, “U phase voltage, V phase voltage, W phase voltage”) eu, ev, ew is expressed as eu = Em × sinωt.
ev = Em × sin (ωt−2π / 3)
ew = Em × sin (ωt−4π / 3)
And 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.
[0018]
As shown in FIG. 2, the U-phase voltage eu is negative, the V-phase voltage ev is positive, the W-phase voltage ew is positive, and the time when the U-phase voltage eu reaches a substantially negative maximum value is time t0. . Therefore, as shown in FIG. 3A, the diode D4 is turned on, and a current id4 flows from the negative output side. The forward voltage drop Vf of the diode D4 is regarded as approximately 0 volts.
[0019]
On the other hand, the diode D1 is cut off, and the absolute value current Ic of the current ic (hereinafter, the current Ic represents the absolute value of the current ic) flows from the positive output side to the capacitor C1 as a charging current. C1 is charged using a 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, the U-phase current Iu is U The absolute value of the phase current iu).
Iu = id4 + Ic (1)
It is. 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 displayed as absolute values. The absolute value voltage of the U-phase voltage eu is defined as voltage Eu. Hereinafter, the currents and the like displayed in absolute values are for clarifying the direction in which the current flows.
[0020]
Further, the charging voltage of the capacitor C1 is set to the voltage Vc. As will be described later, the capacitor C1 is already charged before the time t0, but after the 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 charging current of the capacitor to the discharging current as shown in FIG. At this time, the U-phase current Iu is
Iu = Ic-id4 (2)
It is.
[0021]
When the current Ic changes from the charging current to the discharging current (this time is tc), the V-phase voltage ev is lower than the U-phase voltage eu as shown in FIG. The diode D5 to which the V-phase voltage ev is applied eventually becomes conductive, and the current id4 flowing through the diode D4 flows to the diode D5, and the diode D4 is cut off. The time when the diode D4 is cut off in this way is t1, and at this time, the anode-cathode voltage of the diode D4 becomes a reverse voltage. When this reverse voltage is Vr, Vr is negative.
[0022]
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 that includes the inductance L1 and the capacitor C1 (hereinafter, the resonance circuit that resonates at the power supply frequency is referred to as “resonance circuit”). Is displayed).
When the time t1 has elapsed, as described above, the diode D4 is cut off and the current Ic is already the discharge current of the voltage Vc of the capacitor C1. Here, during the period until the capacitor C1 is completely discharged, as shown in FIG. 3C, the diode D1 connected in parallel to 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 are equal,
Iu = Ic (3)
It becomes. When the capacitor C1 is completely discharged, the diode D1 becomes conductive and the current id1 flows. The time when the diode D1 becomes conductive in this way is t2.
[0023]
On the other hand, during the period from time t1 to time t2, the reverse voltage Vr of the diode D4 gradually increases from 0V as the voltage Vc decreases due to the discharge of the capacitor C1.
Thus, a resonance current flows through the resonance circuit of the inductance L1 and the capacitor C1 during the period from time t1 to time t2.
[0024]
As described above, when the capacitor C1 is completely discharged and the current id1 flows through the diode D1 (after the time t2 has elapsed), the voltage Vc (the same voltage as the forward voltage drop Vf of the diode D1) becomes approximately 0 volts. At this time, the U-phase current Iu and the absolute value Id1 of the current are equal (hereinafter, the current Id1 represents the absolute value of the U-phase current id1).
Iu = Id1 (4)
Thus, the U-phase current iu (current id1) is supplied from the output terminal OUT1 to the load. Eventually, the polarity of the U-phase current iu is inverted, and this inversion time is defined as time t3.
[0025]
As described above, from time t2 to time t3, the inductance L1 does not constitute a resonance circuit with the capacitor C1. However, as shown in FIG. 4, the diode rectifier circuit 10 has an inductance L2 and a capacitor C2 as a resonance circuit in the V phase, and an inductance L3 and a capacitor C3 as a resonance circuit in the W phase. (Current flowing out from the input power supply terminals 2 and 3) flows to the power supply input terminal 1 via the inductance L1.
[0026]
Thus, a resonance current flows through the inductance L1 during the period from time t2 to time t3.
FIG. 4 omits the illustration of the shut-off diode, and shows only the conducting diode. Since the diode 1 is conductive, the capacitor C1 does not act as a capacitor and is not shown in the figure.
[0027]
At time t3, the polarity of the U-phase current iu is reversed, the diode D1 is cut off, and even after the time t3 has passed, the diode D4 is not yet conductive. (Charging) Current ic flows and voltage Vc rises. This current is a U-phase current iu. Therefore, during this period, the U-phase current Iu and the current Ic are equal,
Iu = Ic (5)
It becomes.
[0028]
On the other hand, the reverse voltage Vr is applied to the diode D4 after the time t1, but when the rectified output voltage generated at the output terminals OUT1 and OUT2 is V10,
V10 = Vc + Vr
It is. Here, the rectified output voltage V10 is a voltage having the highest absolute value of each instantaneous voltage generated at the power input terminals 1 and 2 by the U-phase voltage eu, the V-phase voltage ev, and the W-phase voltage ew. Therefore, the rectified output voltage V10 is a voltage linked (related) to the V-phase voltage ev and the W-phase voltage ew as well as the U-phase voltage eu.
[0029]
Then, the reverse voltage Vr that shuts off the diode D4 temporarily rises linked to the V-phase voltage ev and the W-phase voltage ew, but eventually, with the rise of the voltage Vc and the fall of the rectified output voltage V10, The reverse voltage Vr of the diode D4 drops to 0 volts, the polarity of the anode-cathode voltage of the diode D4 is inverted, and the diode D4 becomes conductive. The time when the diode D4 is turned on is defined as time t4. At this time, the capacitor C1 is continuously charged with the current ic.
[0030]
Thus, a resonance current flows through the resonance circuit of the inductance L1 and the capacitor C1 during the period from time t3 to time t4.
Here, the operating state of the diode rectifier circuit 10 at the time t4 is the same as the operating state of the diode rectifier circuit 10 at the time t0, and the capacitor C1 is already charged at the time t0 as described above. Thus, the diode rectifier circuit 10 repeats the operation during the period from the time t0 to the time t4 described above.
[0031]
The continuous operation of the diode rectifier circuit 10 described for each period is shown in FIG. The current ic in FIG. 2 is negative at time t0 (current ic flows from the positive output side to the power input terminal 1), but changes positively before reaching time t1. This corresponds to FIGS. 3 (a) and 3 (b). In FIG. 2, a substantially rectangular wave current is superimposed on the current ic during the period from the time t0 to the time t1, but during this period, the diode D4 conducts and the current id4 flows, and the current ic passes through the capacitor C1. This is because the current id4 decreases the absolute value of the current ic when the battery is charged, and the current id4 increases the absolute value of the current ic when the current ic becomes the discharge current of the capacitor C1. As described above, the current ic continues to flow as a discharge current from time t2 to no longer in 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.
[0032]
As for the currents id4 and id1 shown in FIG. 2, the current id4 having a substantially rectangular wave 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 no resonance current flows through the diode D4. Therefore, the current id4 becomes a substantially rectangular wave. As described above, during the period from time t2 to time t3, current from the V-phase / W-phase resonance circuit flows through the diode D1, and the waveform of the current id1 is a waveform that is a part of a substantially sine wave. From time t1 to time t2 and from time t3 to time t4, both the diodes D1 and D4 are cut off as described above.
[0033]
The voltage Vc (the voltage of the capacitor C1) in FIG. 2 shows a state where the battery is charged with the above-described 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 is changed to discharge, and is completely discharged at the time t2 as described above.
A 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 the period from time t1 to time t4, the diode D4 is cut off.
[0034]
When the U-phase current iu flows out of the power supply input terminal 1 during the period from time t0 to time t1, the relationship (1), Iu = id4 + Ic is established as described above, and the current ic and current in FIG. The current waveform of the sum of id4 becomes a substantially sine wave by the resonance circuit of the inductance L1 and the capacitor C1. When the direction of the U-phase current iu is reversed, the relationship of equation (2), Iu = Ic−id4 is established as described above, and the current waveform obtained by subtracting the current id4 from the current ic in FIG. Become a wave.
[0035]
Similarly, from time t1 to time t2, the current ic in FIG. 2 and the above equation (3), from Iu = Ic, and from time t2 to time t3, the current id1 in FIG. 2 and the above equation (4), Iu = Id1 From time t3 to time t4, from the current ic in FIG. 2 and the above equation (5), Iu = Ic, the U-phase current iu is also substantially sinusoidal by the resonance circuit.
Thus, the U-phase current iu flowing by the U-phase power supply Ug is sine-waved by the resonance circuit from time t0 to t4 (for one period of the three-phase AC power supply).
[0036]
Similarly, the V-phase current iv flowing by the V-phase power supply Vg and the W-phase current iw flowing by the W-phase power supply Wg are also made sinusoidal by the resonance circuit.
In the diode rectifier circuit 10 described above, when the harmonic current of the U-phase current iu of the three-phase AC power source was measured, the harmonic current was improved, and a slight (about 3%) even-order harmonic current was obtained. It was only included. The waveform of this U-phase current iu is shown in FIG. FIG. 6B shows the rectified output voltage V10 of the diode rectifier circuit 10.
[0037]
FIG. 5 is a block diagram showing a diode rectifier circuit according to a second embodiment of the present invention, which is a diode rectifier circuit that obtains DC power from a three-phase AC power source. The diode rectifier circuit 20 is intended to further improve the even-order harmonic current than the diode rectifier circuit of the first embodiment. In addition, about the component which has a function similar to 1st embodiment, the same code | symbol is attached | subjected and shown, and the description is abbreviate | omitted.
[0038]
Compared with the diode rectifier circuit 10, the diode rectifier circuit 20 has a capacitor C4 connected to the diode D4, a capacitor C5 connected to the diode D5, and a capacitor C6 connected to the diode D6 in parallel. These capacitors form resonance circuits with the inductances L1 to L3 in the same manner as the capacitors C1 to C3.
In the diode rectifier circuit 10 described above, the capacitors C1 to C3 are connected in parallel to the diodes D1 to D3 on the positive output side, so that the positive output side and the negative output side of the three-phase diode bridge circuit are asymmetrical. Thus, there was some even-order harmonic current (about 3%). In the diode rectifier circuit 20, the symmetry of the circuit is improved with the above-described configuration.
[0039]
When the harmonic current of the U-phase current iu was measured in the diode rectifier circuit 20, the even-order harmonic current that was included in the diode rectifier circuit 10 by about 3% was reduced and almost no longer included. The waveform of this U-phase current iu is shown in FIG. FIG. 7B shows the 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 output side, the capacitors C1 and C4, the capacitors C2 and C5, and the capacitors C3 and C6 are connected in series, and further connected in series. Are connected in parallel and act as a smoothing capacitor between the output terminals OUT1 and OUT2. Therefore, the rectified output voltage V20 of the diode rectifier circuit 20 has a smoother voltage waveform than the rectified output voltage V10 (FIG. 6B) of the diode rectifier circuit 10 as shown in FIG. 7B. Yes.
[0040]
Thus, the diode rectifier circuit of the second embodiment can omit the smoothing circuit including the inductance Lf and the capacitor Cf in the first embodiment.
FIG. 8 is a block 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. In addition, about the component which has a function similar to 1st embodiment, the same code | symbol is attached | subjected and shown, and the description is abbreviate | omitted.
[0041]
As shown in FIG. 8, the diode rectifier circuit 30 further includes triacs D31 to D33 (switching elements) in addition to the diode rectifier circuit 10. 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.
[0042]
The diode rectifier circuit 30 sine-waves the AC input current in the same manner as the diode rectifier circuit 10, and the triac control circuit 34 controls the phase of the gates of the triacs D31 to D33 via the control lines 34a to 34c. The conduction angles of the U-phase current iu, the V-phase current iv, and the W-phase current iw are controlled. By this phase control of the conduction angle, the rectified output voltage V30 of the diode rectifier circuit 30 is controlled. When a failure occurs in the diode rectifier circuit 30 or the load resistor RL, the triacs D31 to D33 also function as a protection circuit by setting the conduction angle of the U-phase current iu to the W-phase current iw to zero.
[0043]
Needless to say, the triacs D31 to D33 can be inserted in the rectifier circuit 20 as well.
FIG. 9 is a configuration diagram showing a fourth embodiment of a 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 positive output diodes D1 and D2 and negative output diodes D3 and D4. The positive output diodes D1 and D2 include parallel capacitors C1 and D2, respectively. C2 is connected in parallel.
[0044]
The single-phase AC power supply E has 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. 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 is supplied to the load resistor RL.
[0045]
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, and the current flowing into the power supply input terminal 2 Becomes a similar resonance current by the resonance circuit of the inductance L2 and the capacitor C2.
Thus, the diode rectifier circuit 40 can sine-wave the current flowing into the power supply input terminals 1 and 2 and reduce the generation of harmonic current.
[0046]
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 that obtains DC power from a single-phase AC power supply. In addition, about the component which has the function similar to 4th embodiment, the same code | symbol is attached | subjected and shown, The description is abbreviate | omitted.
In the diode rectifier circuit 50, parallel capacitors C3 and C4 are connected in parallel to the diodes D3 and D4 on the negative output side in the diode rectifier circuit 40, respectively, and these capacitors have an inductance L1 as in the capacitors C1 and C2. And L2 and a resonance circuit are formed.
[0047]
The diode rectifier circuit 50 configured in this way has a circuit configuration in which the single-phase diode bridge circuit is symmetric, and can further reduce the generation of even-order harmonic currents as in the second embodiment.
In addition, 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 function as smoothing capacitors. Therefore, the smoothing circuit including the inductance Lf and the capacitor Cf in the fourth embodiment is provided. Can be omitted.
[0048]
FIG. 11 is a configuration diagram showing a sixth embodiment of a diode rectifier circuit according to the present invention, which is a diode rectifier circuit 70 that obtains DC power from a single-phase AC power supply. In addition, about the component which has the function similar to 4th embodiment, the same code | symbol is attached | subjected and shown, The description is abbreviate | omitted.
In the diode rectifier circuit 70, triacs D71 and D72 are further added to the diode rectifier circuit 40 as shown in FIG. The triac D71 is interposed 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.
[0049]
The diode rectifier circuit 70 sine-waves the current flowing into the power input terminals 1 and 2 in the same manner as the diode rectifier circuit 40, and the triac control circuit 74 connects the gates of the triacs D71 and D72 to the control lines 74a and 74b. To control the conduction angle of the input current of the diode rectifier circuit 70. By this phase control of the conduction angle, the rectified output voltage V70 of the diode rectifier circuit 70 is controlled. When a failure occurs in the diode rectifier circuit 70, the load resistor RL, etc., the triacs D71 and D72 act as a protection circuit for the diode rectifier circuit 70 by setting the conduction angle of the input current of the diode rectifier circuit 70 to zero.
[0050]
It goes without saying that the triacs D71 and D72 for controlling the conduction angle can be similarly inserted in the diode rectifier circuit 50.
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 depart from the spirit of reducing the generation of harmonic current by making the AC input current of the diode rectifier circuit a sine wave. However, there is no problem that there is an error.
[0051]
The present invention is not limited to the above-described embodiment, and an inductance interposed between the power input terminal of the diode bridge rectifier circuit and the power source, and a capacitor connected in parallel to the diode of the diode bridge rectifier circuit, Therefore, the present invention can be implemented within a range that does not depart from the purpose of configuring the resonance circuit and converting the AC input current of the diode rectifier circuit into a sine wave.
[0052]
【The invention's effect】
As described above, according to the diode rectifier circuit of the present invention, only a passive element having a simple circuit configuration without using a high-frequency switching element, and therefore, the AC input of the diode rectifier circuit can be produced at low cost and without generating switching noise. The current is made sinusoidal, the generation of harmonic current is reduced, the distortion of the voltage and current waveforms of the power supply system that supplies AC power to the diode rectifier circuit is reduced, and the power factor of the power supply system is not reduced. Demonstrated.
[0053]
Further, by connecting the capacitors constituting the resonance circuit to the positive output side and the negative output side in the diode bridge circuit, an effect that the smoothing inductance and the smoothing capacitor of the smoothing circuit can be omitted is also 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 is an operation diagram showing rectification of a U-phase voltage eu and changes in a U-phase current iu of the diode rectifier circuit according to the first embodiment.
4 is a configuration diagram showing a configuration of a resonance circuit in the state of FIG.
FIG. 5 is a configuration diagram of a diode rectifier circuit (three-phase alternating current) of a second embodiment of the diode rectifier circuit according to the present invention.
FIG. 6 is a waveform diagram showing waveforms of a U-phase current iu and a rectified output voltage V10 of the diode rectifier circuit according to the first embodiment.
FIG. 7 is a waveform diagram showing waveforms of a U-phase current iu and a rectified output voltage V20 of the diode rectifier circuit according to the second embodiment.
FIG. 8 is a configuration diagram of a diode rectifier circuit (three-phase alternating current) of 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 alternating current) of 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 alternating current) of 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 alternating current) of a sixth embodiment of the diode rectifier circuit according to the present invention.
[Explanation of symbols]
1, 2, 3 Power input terminal
C1-C6 capacitors
D1-D6 diode
D31-D33, D71, D72 Triac
L1 to L3 Inductance
E Single-phase power supply
Ug U-phase power supply (3-phase AC power supply)
Vg U-phase power supply (three-phase AC power supply)
Wg W-phase power supply (three-phase AC power supply)

Claims (6)

A three-phase diode bridge circuit comprising first to sixth diodes and connected to a three-phase AC power source to obtain a rectified output;
First to third capacitors respectively connected in parallel to the first to third diodes on the positive output side in the three-phase diode bridge circuit;
Resonance equal to the frequency of the three-phase AC power source between the first to third capacitors, which is inserted in series between each power source input terminal of the three-phase diode bridge circuit and the three-phase AC power source. A diode rectifier circuit comprising first to third inductances forming a frequency resonant circuit. The diode rectifier circuit according to claim 1, wherein
The diode rectifier circuit further comprising fourth to sixth capacitors respectively connected in parallel to the fourth to sixth diodes on the negative output side in the three-phase diode bridge circuit. The diode rectifier circuit according to claim 1 or 2,
First to third phase-controllable AC inputs of the three-phase diode bridge circuit are inserted in series between the power input terminals of the three-phase diode bridge circuit and the first to third inductances, respectively. A diode rectifier circuit comprising: a switching element. A single-phase diode bridge circuit consisting of first to fourth diodes and connected to a single-phase AC power source to obtain a rectified output thereof;
First and second capacitors respectively connected in parallel to the first and second diodes on the positive output side in the single-phase diode bridge circuit;
Resonance equal to the frequency of the single-phase AC power supply between the first and second capacitors inserted in series between each power supply input terminal of the single-phase diode bridge circuit and the single-phase AC power supply. A diode rectifier circuit comprising first and second inductances forming a frequency resonant circuit. The diode rectifier circuit according to claim 4,
The diode rectifier circuit further comprising third and fourth capacitors connected in parallel to the third and fourth diodes on the negative output side in the single-phase diode bridge circuit, respectively. The diode rectifier circuit according to claim 4 or 5,
First and second phase-controlling the AC input of the single-phase diode bridge circuit, which are inserted in series between the power input terminals of the single-phase diode bridge circuit and the first and second inductances, respectively. A diode rectifier circuit comprising: a switching element.

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