JP2002058250A - Three-phase rectifying device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a one converter type of three-phase rectifying device which is simple of circuit constitution, and is small in number of used conversion devices, and is of high power factor, and is easy of control. SOLUTION: A control circuit 3 gives the same control signal to drive circuits 16, 26, and 36, and turns on or turns off transistors 15, 25, and 35. When AC voltage is inputted into single-phase full wave diode rectifiers 11, 21, and 31, they output full-wave-rectified voltage. This DC voltage is applied intermittently to the primary side of transformers 14, 24, and 34 by the above control, and the reset of these transformers is performed each by diodes 13, 23, and 33, and it is converted into high-frequency AC, and in the secondary circuit, it is full-wave-rectified by diodes 18, 28, and 38. The above rectified output is halved equally into a positive electrode and a negative electrode by reactors 19, 29, and 39, and it becomes DC output, being smoothed by a capacitor 2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a three-phase rectifier for converting three-phase alternating current to direct current, and more particularly to a one-converter three-phase rectifier.

[0002]

2. Description of the Related Art As a conventional three-phase high power factor rectifier in which AC input and DC output are insulated, the number of stages of conversion switching devices in a main circuit is a three-phase boost chopper type high power factor rectifier and an isolation transformer. There is a two-converter type that includes two stages of DC / DC converters. Also, as a one-converter isolated three-phase high power factor rectifier with one conversion stage, three single-phase input flyback converter rectifiers are used, and a delta ( Δ) Some are connected.

[0003]

However, in the conventional two-converter three-phase high power factor rectifier,
Since the number of conversion stages is two, a general circuit configuration requires six conversion switching devices in the three-phase high power factor rectifier unit and four conversion switching devices in the DC / DC converter unit. There was a problem that became worse. Also,
The high power factor rectifier section needs to individually control three-phase AC input, and the DC / DC converter section also needs to control another loop, which has a problem that the circuit becomes complicated.
Also, in the conventional one-converter three-phase high power factor rectifier, it is difficult to increase the capacity of the flyback transformer, and when controlling with a single control circuit, three sets of flyback rectifiers having the same characteristics are required. And so on.
There is also a method of controlling the three rectifiers individually to make the characteristics uniform, but there is a problem that the control becomes complicated.

[0004] In view of the above-mentioned problems, an object of the present invention is to provide a simple circuit configuration, a small number of switching devices, and
An object of the present invention is to provide a one-converter three-phase rectifier with a high power factor and easy control.

[0005]

According to the first aspect of the present invention,
Single-phase full-wave diode rectifiers (for example, single-phase full-wave diode rectifiers 11, 21,
31) Connect the positive side of the output to the center of the primary side of a center tap transformer (for example, transformers 14, 24, 34), and start winding the primary side of the center tap transformer with diodes (for example, diodes 13, 23, 33). A cathode is connected, the anode of the diode is connected to the negative side of the single-phase full-wave diode rectifier output, and the primary winding end of the center tap transformer is connected to the collector of a transistor (eg, transistors 15, 25, 35). Then, the emitter of this transistor is connected to the negative side of the output of the single-phase full-wave diode rectifier, and a driving circuit (for example, driving circuits 16, 26, 36) for driving the transistor is connected between the base and the emitter of this transistor. And a capacitor that absorbs the excitation energy when the transistor is off (for example, Capacitors 12, 22, 32)
Is connected between the outputs of the single-phase full-wave diode rectifier, and the anode of a first diode (for example, diodes 17, 27, 37) is connected to the beginning of the secondary winding of the center tap transformer. The cathode of the second
Diodes (eg, diodes 18, 28, 38)
The anode of the second diode is connected to the end of the secondary winding of the center tap transformer, and the cathode and the anode of the second diode are separated into two windings on the positive electrode side and the negative electrode side. Then, one end of each winding of a reactor (eg, reactors 19, 29, 39) operating so that the respective outputs of the positive electrode and the negative electrode become the same is connected, and the other end of each of these windings is connected to the positive electrode of the DC output. Single-phase forward converters (e.g., single-phase forward converters 10, 20, 30) connected to the negative side and the negative side, respectively.
Three sets are provided, each AC input stage of each single-phase forward converter is delta-connected between the three-phase AC input lines, and each DC output stage of each single-phase forward converter is connected to the positive and negative sides of the DC output. And a control circuit (for example, control circuit 3) commonly connected to each DC output stage of each single-phase forward converter and commonly connected to each drive circuit.
Detects a positive voltage and a negative voltage from the DC output stage,
Each drive circuit in each of the single-phase forward converters is driven and controlled by the same drive signal based on these detection results.

According to the first aspect of the present invention, since three sets of single-phase forward converters each having one conversion device are provided, the control method is simplified, and a simple circuit configuration and three The power factor of the phase AC input can be increased. In addition, since a control circuit for controlling three sets of single-phase forward converters with the same control signal is provided, it is possible to convert the three-phase AC input into a sine wave by flowing an input current corresponding to the instantaneous value of the input voltage. it can.

[0007]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a diagram illustrating a circuit configuration of a three-phase rectifier according to an embodiment of the present invention. First, the configuration will be described. In FIG. 1, a three-phase rectifier 1 is a three-terminal input two-terminal output device having input terminals U, V, and W and output terminals P and N. This is a device that converts a phase AC voltage into a DC voltage that is insulated from the three-phase AC voltage. The three-phase rectifier 1 includes single-phase forward converters 10, 20, and 30, a control circuit 3, and a capacitor 2.

The input terminals U, V, and W have U-phase, V-phase, and W-phase, respectively.
A three-phase AC voltage consisting of three phases is input. Note that U
Each of the AC voltages of the phase, the V phase, and the W phase has the same effective value, and the phases are different from each other by 120 degrees.

The single-phase forward converter 10 includes a single-phase full-wave diode rectifier 11, a capacitor 12, a diode 13, a transformer 14, a transistor 15, and a drive circuit 1.
6, diode 17, diode 18, reactor 19
Consists of

The single-phase full-wave diode rectifier 11 includes a diode 11a, a diode 11b, a diode 11c, and a diode 11d. The anode of the diode 11a is connected to the cathode of the diode 11c. The anode of the diode 11b is connected to the cathode of the diode 11d. Have been. Also, the diode 11a and the diode 11
The respective cathodes of b are connected to each other, and the respective anodes of the diodes 11c and 11d are connected to each other. A connection point between the diode 11a and the diode 11c is connected to an input terminal U and a connection point between a diode 31b and a diode 31d described later. A connection point between the diode 11b and the diode 11d is connected to the input terminal V and a diode 21a described later. It is connected to the connection point of the diode 21c.

The single-phase forward converter 20 includes a single-phase full-wave diode rectifier 21, a capacitor 22, a diode 23, a transformer 24, a transistor 25, and a drive circuit 2.
6, diode 27, diode 28, reactor 29
Consists of

The single-phase full-wave diode rectifier 21 includes a diode 21a, a diode 21b, a diode 21c, and a diode 21d. The anode of the diode 21a is connected to the cathode of the diode 21c. The anode of the diode 21b is connected to the cathode of the diode 21d. Have been. Also, the diode 21a and the diode 21
The cathodes of b are connected to each other, and the anodes of the diodes 21c and 21d are connected to each other. The connection point between the diode 21a and the diode 21c is connected to the input terminal V, the diode 11b and the diode 1b.
The connection point of 1d is connected, and the connection point of the diode 21b and the diode 21d is connected to the input terminal W and the connection point of the diode 31a and the diode 31c described later.

The single-phase forward converter 30 includes a single-phase full-wave diode rectifier 31, a capacitor 32, a diode 33, a transformer 34, a transistor 35, and a driving circuit 3.
6, diode 37, diode 38, reactor 39
Consists of

The single-phase full-wave diode rectifier 31 includes a diode 31a, a diode 31b, a diode 31c, and a diode 31d. The anode of the diode 31a is connected to the cathode of the diode 31c. The anode of the diode 31b is connected to the cathode of the diode 31d. Have been. Also, the diode 31a and the diode 31
The respective cathodes of b are connected to each other, and the respective anodes of the diodes 31c and 31d are connected to each other. The connection point between the diode 31a and the diode 31c is the input terminal W, the diode 21b and the diode 2b.
The node between the diode 31b and the diode 31d is connected to the input terminal U and the node between the diode 11a and the diode 11c.

The capacitors 12, 22, and 32 are connected between the positive and negative electrodes of the single-phase full-wave diode rectifiers 11, 21, and 31, respectively. Capacitors 12, 22, 3
Reference numeral 2 denotes a small capacity, and transistors 15, 25, 3
Absorbs the excitation energy of the transformers 14, 24, 34 when 5 is off.

The diodes 13, 23, and 33 have their cathodes connected to the winding start of the primary sides of the transformers 14, 24, and 34, respectively, and their anodes serve as the negative electrodes of the single-phase full-wave diode rectifiers 11, 21, and 31, respectively. They are connected to return the excitation energy stored in the transformers 14, 24, 34, respectively.

In the transformers 14, 24, and 34, the cathodes of the diodes 13, 23, and 33 are connected at the beginning of winding on the primary side, and the collectors of the transistors 15, 25, and 35 are connected at the end of winding.

The transistors 15, 25, and 35 have their collectors connected to the winding ends of the transformers 14, 24, and 34, respectively, and their emitters connected to the negative electrodes of the single-phase full-wave diode rectifiers 11, 21, and 31, respectively. .
Each base has a control circuit 3 to a drive circuit 16,
A control signal is input via 26 and 36 to control on / off between the collector and the emitter.

The driving circuits 16, 26, and 36 include a control circuit 3
And the transistors 15, 25, and 35, and receives the same control signal from the control circuit 3, and applies the control signals to the transistors 15, 25, and 35 to drive them.

Each of the diodes 17, 27, and 37 has its anode connected to the beginning of secondary winding of the transformers 14, 24, and 34, and its cathode connected to the diode 1 respectively.
8, 28 and 38 are connected to the cathode.

The diodes 18, 28, and 38 have their anodes connected to the ends of the secondary windings of the transformers 14, 24, and 34, respectively, and their cathodes connected to the diode 1 respectively.
7, 27 and 37 are connected to the cathodes.

The reactors 19, 29 and 39 are divided into two turns, and one end of each of the two turns is connected to the cathode and anode of the diode 18, 28 and 38, respectively. Are connected to the positive and negative sides of the single-phase forward converters 10, 20, and 30, respectively.

Single-phase forward converters 10, 20, 3
0 is connected in parallel via the respective reactors 19, 29 and 39.

The control circuit 3 is commonly connected to each of the DC output stages of the single-phase forward converters 10, 20, and 30, and has a drive circuit 1 for the transistors 15, 25, and 35.
6, 26, and 36, and detects a positive voltage and a negative voltage from the DC output stage, and supplies the same control signal to each of the driving circuits 16, 26, and 36 based on the detection results.

The capacitor 2 has one end connected to the output terminal P and the other end connected to the output terminal N. The capacitor 2 includes single-phase forward converters 10, 20,
It converts the input voltage from 30 to a smoothed DC voltage.

Next, the operation of this embodiment will be described with reference to FIG. FIG. 2 is a time chart for explaining the circuit operation of the three-phase rectifier 1 of FIG. FIG. 2 (a)
FIG. 2B shows the relationship between the detection voltage and the triangular wave.
3A shows a comparison output value generated from the detection voltage and the triangular wave. FIG. 2C shows a voltage applied to the diode 18, FIG. 2D shows a voltage applied to the diode 28, and FIG. 2E shows a voltage applied to the diode 38. . 2F shows a current flowing in the reactor 19, FIG. 2G shows a current flowing in the reactor 29, and FIG. 2H shows a current flowing in the reactor 39. FIG. 2 (i) shows single-phase forward converters 10 and 3
FIG. 2 shows a U-phase current obtained by synthesizing each current input to 0.
(J) shows a V-phase current obtained by combining the currents input to the single-phase forward converters 10 and 20, and FIG.
Indicates a W-phase current obtained by combining the currents input to the single-phase forward converters 20 and 30.

Before describing the circuit operation of the three-phase rectifier 1, each single-phase forward converter 1
The on / off control of 0, 20, and 30 will be described.

As shown in FIG. 2A, the control circuit 3
Compare the detected value of the triangular wave with the DC output voltage, and when the triangular wave is equal to or greater than the detected voltage,
When the triangular wave is smaller than the detection voltage, the voltage level of L is
Output as comparison output.

When the comparison output value is at the H voltage level, the control circuit 3 turns on the transistors 15, 25, and 35 with the same signal via the drive circuits 16, 26, and 36, respectively, so that the comparison output value is In the case of the voltage level of L, the transistors 1, 26, 36
5, 25 and 35 are turned off by the same signal.

The control circuit 3 includes transistors 15, 25,
The on / off operation of 35 controls the voltage input to single-phase forward converters 10, 20, 30. Specifically, the control circuit 3 controls the three-phase AC voltages input to the three-phase rectifier 1 collectively via the transistors 15, 25, and 35, and the transistors 15, 25, and 35 are simultaneously turned off. In the case of, each AC voltage is converted to a voltage of 0 (V), and when the transistors 15, 25, and 35 are simultaneously turned on, the AC voltage value is output. In addition, by flowing an input current corresponding to the instantaneous value of the AC voltage, the three-phase AC input current is converted into a sine wave, and their waveforms are shown in FIG.
(J) and (k) are obtained.

Hereinafter, the circuit operation of the three-phase rectifier 1 will be described.

In the single-phase forward converter 10,
First, the U-V phase AC voltage is input to the single-phase full-wave diode rectifier 11 to output a full-wave rectified voltage. The primary circuit of the center tap transformer 14 converts the DC output voltage from the single-phase full-wave diode rectifier 11 into a transistor 1
5 center tap transformer 14 by on / off control
To the primary side of the center tap transformer 1
4 is reset by the diode 13 and converted into a high frequency alternating current. In the secondary circuit of the center tap transformer 14, the diode 17 and the diode 1 for direct current return
8, the high-frequency alternating current is rectified, and its voltage is
The result is as shown in FIG.

Similarly, in the single-phase forward converter 20, first, the V-phase is applied to the single-phase full-wave diode rectifier 21.
A -W phase AC voltage is input, and a full-wave rectified voltage is output. The primary circuit of the center tap transformer 24 intermittently applies the DC output voltage from the single-phase full-wave diode rectifier 21 to the primary side of the center tap transformer 24 by controlling on / off of the transistor 25. Is reset by the diode 23 and converted into a high-frequency AC. In the secondary circuit of the center tap transformer 24, the high frequency alternating current is rectified by the diode 27 and the diode 28 for direct current return, and the voltage is as shown in FIG.

Similarly, in the single-phase forward converter 30, first, the single-phase full-wave diode rectifier 31
-A U-phase AC voltage is input, and a full-wave rectified voltage is output. The primary circuit of the center tap transformer 34 intermittently applies the DC output voltage from the single-phase full-wave diode rectifier 31 to the primary side of the center tap transformer 34 by controlling on / off of the transistor 35. Is reset by the diode 33 and converted into a high-frequency AC. In the secondary circuit of the center tap transformer 34, the high-frequency alternating current is rectified by the diode 37 and the diode 38 for direct current return, and the voltage is as shown in FIG.

Reactors 19, 29, and 39 divide the outputs of single-phase forward converters 10, 20, and 30 into a positive electrode and a negative electrode, and operate so that the currents of the positive electrode and the negative electrode become the same. , 39, the output current sharing of each single-phase forward converter 10, 20, 30 is made uniform. Reactors 19, 29,
A current corresponding to the voltage applied to the diodes 18, 28, and 38 flows through 39, as shown in FIGS.
(H) is obtained.

Each single-phase forward converter 10, 20,
The output voltage from 30 is converted to a DC voltage smoothed by capacitor 2 and output to output terminals P and N.

As described above, according to the three-phase rectifier 1 of the embodiment of the present invention, each single-phase forward converter 10, 20, 30 is controlled by the same control signal, and the instantaneous value of the input voltage is reduced. By flowing the appropriate input current, the three-phase AC input current can be converted into a sine wave. In addition, since only one conversion device is required for each of the single-phase forward converters 10, 20, and 30, the control method is simplified, and a simple circuit configuration and a high power factor of a three-phase AC input can be achieved.

[0038]

According to the three-phase rectifier of the present invention, three sets of single-phase forward converters are controlled by the same control signal,
By flowing an input current that matches the instantaneous value of the input voltage,
The three-phase AC input current can be converted into a sine wave. Further, since only one conversion device is required for each single-phase forward converter, the control method is simplified, and a simple circuit configuration and a high power factor of the three-phase AC input can be achieved.

[Brief description of the drawings]

FIG. 1 is a diagram showing a circuit configuration of a three-phase rectifier according to an embodiment to which the present invention is applied.

FIG. 2 is a time chart for explaining the operation of the three-phase rectifier whose circuit configuration is shown in FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Three-phase rectifier 2 Capacitor 3 Control circuit 10, 20, 30 Single-phase forward converter 11, 21, 31 Single-phase full-wave diode rectifier 12, 22, 32 Capacitor 13, 23, 33 Diode 14, 24, 34 Transformer 15, 25, 35 Transistor 16, 26, 36 Drive circuit 17, 27, 37 Diode 18, 28, 38 Diode 19, 29, 39 Reactor

 ────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Masao Wada 2-29-1, Heian-cho, Tsurumi-ku, Yokohama-shi, Kanagawa F-term (reference) 5K006 AA02 CA01 CA07 CB01 CB08 CC04 CC08 DC05 5H730 AA18 BB23 BB82 CC02 EE08 EE10 FD01 FG01

Claims (1)

[Claims] 1. A positive-polarity output of a single-phase full-wave diode rectifier having a line between three-phase AC inputs as an input is connected to the center of the primary side of a center tap transformer. Connect the cathode, connect the anode of this diode to the negative side of the output of the single-phase full-wave diode rectifier, connect the primary winding end of the center tap transformer to the collector of the transistor, and connect the emitter of the transistor to the single-phase full-wave diode rectifier. The single-phase full-wave diode rectifier is connected to the negative side of the output of the full-wave diode rectifier, a drive circuit for driving the transistor is connected between the base and the emitter of the transistor, and a capacitor that absorbs excitation energy when the transistor is off. Connected between the outputs and the first tap at the beginning of the secondary winding of the center tap transformer. Connect the anode of diode connects the cathode of the first diode to the cathode of the second diode, its anode connected to the second diode to winding end secondary side of the center tap transformer,
Further, one end of each winding of a reactor which is divided into two turns on a positive electrode side and a negative electrode side and operates so that each output of the positive electrode and the negative electrode is connected to the cathode and the anode of the second diode is connected. Three sets of single-phase forward converters each having the other end of each winding connected to the positive and negative sides of the DC output, respectively, and connecting each AC input stage of each single-phase forward converter to the line of the three-phase AC input. Delta connection, each DC output stage of each single-phase forward converter is connected between the positive side and the negative side of the DC output, and commonly connected to each DC output stage of each single-phase forward converter. A control circuit commonly connected to the drive circuit detects a positive voltage and a negative voltage from the DC output stage,
A three-phase rectifier, wherein each drive circuit in each of the single-phase forward converters is drive-controlled by the same drive signal based on the detection results.