JP2002058248A - 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 main 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 6 gives the same control signal to drive circuits 16, 26, and 36, and turns on or turns off transistors 15, 25, and 35 so that the current of the reactor 4 may be discontinuous. When AC voltage is inputted into single-phase full wave diode rectifiers 11, 21, and 31, they rectify full waves and output DC voltage. The primary circuit of transformers is converted into high frequency AC through diodes 13, 23, and 33 by applying this DC voltage to the primary side of these transformers 14, 24, and 34 intermittently by the above control, and in the secondary circuit connected directly in series, it is full-wave-rectified by a diode 2 and a diode 3. The above rectified output becomes DC output, being smoothed with a reactor 4 and a capacitor 5.

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, insulating between three-phase alternating current input and direct current output, and converting the three-phase alternating current into a sine wave. In particular, it relates 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 an AC input and a DC output are insulated, the number of conversion stages of a conversion switching device of 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. In addition, as a one-converter isolated three-phase high power factor rectifier having one conversion stage, three single-phase input high power factor rectifiers are used, and a delta (Δ) between three-phase AC input lines is used. Something to connect.

[0003]

However, in the conventional two-converter three-phase high power factor rectifier,
Since the number of conversion stages is two, the number of control switching devices is large, and two control loops are required, so that there has been a problem that the circuit becomes complicated. In addition, among the conventional one-converter three-phase high power factor rectifiers,
In a system in which each output is combined by parallel connection using three sets of single-phase high power factor rectifiers, three sets of control loops are required,
A circuit for adjusting the output current imbalance of the three single-phase high power factor rectifiers is required. In a system in which three sets of single-phase high power factor rectifiers whose outputs are connected in parallel are controlled by a single control loop, output current imbalance is obtained by a reactor. There is a problem that imbalance occurs.

An object of the present invention is to provide a one-converter three-phase rectifier having a simple main circuit configuration, a small number of switching devices, a high power factor, and easy control in view of the above problems. is there.

[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 rectifiers, and a single-phase forward converter (eg, single-phase forward converters 10, 20, 3
0) are provided, and each AC input stage of each single-phase forward converter is delta-connected between the three-phase AC input lines,
The output of each single-phase forward converter connects the end of the center tap transformer secondary winding of the first single-phase forward converter to the start of the center tap transformer secondary winding of the second single-phase forward converter, The center tap transformer secondary winding end of the single-phase forward converter is connected to the center tap transformer secondary winding start of the third single-phase forward converter, and three center tap transformers are connected in series as a whole. Of the center tap transformer secondary side of the single-phase forward converter is connected to the anode of an output rectifier diode (eg, diode 2), and the cathode of this output rectifier diode is connected to a filter reactor (eg, reactor 4).
And the other end of this filter reactor is connected to the positive side of the total DC output, and the secondary winding end of the center tap transformer of the third single-phase forward converter is connected to the flywheel diode (for example, diode 3). Connected to the anode, the connection point is connected to the negative side of the total DC output, the cathode of this flywheel diode is connected to the cathode of the output rectifier diode, and commonly connected to the total DC output stage of each single-phase forward converter. A control circuit (for example, a control circuit 6) commonly connected to each of the drive circuits detects a positive voltage and a negative voltage from the DC output stage, and based on the detection results, each drive in each single-phase forward converter. It is characterized in that the circuits are driven and controlled by the same drive signal.

According to the first aspect of the present invention, the outputs of three sets of single-phase forward converters are connected in series, each single-phase forward converter is controlled by the same control signal, and the current of the filter reactor is controlled in the discontinuous mode. By flowing a current corresponding to the instantaneous value of the input voltage of each single-phase forward converter, the three-phase AC current can be converted into a sine wave. Also, since only one conversion device is required for each forward converter, the control method is simplified,
A simple main circuit configuration and a high power factor of a three-phase AC input can be realized.

[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. The three-phase rectifier 1 of FIG. 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, 30 and diodes 2, 3,
, A reactor 4, a capacitor 5, and a control circuit 6.

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 16.
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 26.
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 drive circuit 36.
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. On the primary side of the transformers 14, 24, 34, a current proportional to the voltage applied to the primary side flows.

The secondary winding end of the transformer 14 and the secondary winding start of the transformer 24 are connected, and the secondary winding end of the transformer 24 and the secondary winding start of the transformer 34 are connected. Transformers 14, 24, 34 are connected in series.

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 6 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 6
And the transistors 15, 25, and 35, and receives the same control signal from the control circuit 6, and applies the control signal to the transistors 15, 25, and 35 to drive them.

The diode 2 has its anode connected to the beginning of the secondary winding of the transformer 14 and its cathode connected to the cathode of the diode 3.

The diode 3 has its anode connected to the secondary winding end of the transformer 34 and its cathode connected to the cathode of the diode 2.

The reactor 4 has one end connected to the diode 2.
And the other end is connected to the positive side of the total output of the single-phase forward converters 10, 20, 30. The secondary side combined voltage of the center tap transformers 14, 24, 34 is applied to the reactor 4.

The capacitor 5 has one end connected to the output terminal P and the other end connected to the output terminal N, and converts the input current from the single-phase forward converters 10, 20, 30 into a DC current.

The control circuit 6 is connected to the integrated DC output stage of the single-phase forward converters 10, 20, and 30 and drives the transistors 15, 25, and 35.
6 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 drive circuits 16, 26 and 36 based on the detection results.

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 current flowing through the reactor 4.
FIG. 2D shows the output current of the single-phase full-wave diode rectifier 11, and FIG.
2 (f) shows the output current of the single-phase full-wave diode rectifier 31. FIG. FIG. 2G shows a U-phase current obtained by combining the currents input to the single-phase forward converters 10 and 30, and FIG. 2H shows each current input to the single-phase forward converters 10 and 20. Synthesized V
FIG. 2 (i) shows a W-phase current obtained by combining the currents input to the single-phase forward converters 20 and 30.

Before explaining 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 6
The triangular wave is compared with the detection value of the total DC output voltage of the single-phase forward converters 10, 20, 30. If the triangular wave is equal to or larger than the detected voltage, the voltage level of H (high) is set. In this case, the L (low) voltage level is output as a comparison output.

When the comparison output value is at the voltage level of H, the control circuit 6 turns on the transistors 15, 25, and 35 with the same signal via the drive circuits 16, 26, and 36, respectively. 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 6 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 6 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.

When the on / off operation frequency of the transistors 15, 25, and 35 is set so that the current of the reactor 4 becomes discontinuous, each of the single-phase forward converters 10, 20, and
The 30 input currents have sinusoidal peak values, and their waveforms are as shown in FIGS. 2 (g), (h) and (i).

The circuit operation of the three-phase rectifier 1 when the on / off operations of the transistors 15, 25, 35 are controlled as described above will be described below.

In the single-phase forward converter 10,
First, an AC voltage of the U-V phase is input to the single-phase full-wave diode rectifier 11 and full-wave rectified.
As shown in FIG. When the DC output voltage of the full-wave rectification is intermittently applied to the primary side of the center tap transformer 14 by on / off control of the transistor 15, a current proportional to the applied voltage flows through the primary side of the transformer 14. In the primary circuit of the center tap transformer 14,
The intermittent DC output voltage is converted to a high-frequency AC through a reflux diode 13. Capacitor 12 absorbs a surge voltage caused by the excitation energy of center tap transformer 14 generated when transistor 15 is turned off.

Similarly, in the single-phase forward converter 20, first, the V-phase is applied to the single-phase full-wave diode rectifier 11.
The W-phase AC voltage is input and full-wave rectified, and the output current is as shown in FIG. When the DC output voltage of the full-wave rectification is intermittently applied to the primary side of the center tap transformer 24 by ON / OFF control of the transistor 25, a current proportional to the applied voltage flows through the primary side of the transformer 24. In the primary circuit of the center tap transformer 24, the intermittent DC output voltage is converted into a high-frequency AC through the reflux diode 23. Capacitor 22
Absorbs a surge voltage caused by the excitation energy of the center tap transformer 24 generated when the transistor 25 is turned off.

Similarly, in the single-phase forward converter 30, first, the W-phase full-wave diode rectifier 31
The U-phase AC voltage is input and full-wave rectified, and the output current is as shown in FIG. When the DC output voltage of the full-wave rectification is intermittently applied to the primary side of the center tap transformer 34 by ON / OFF control of the transistor 35, a current proportional to the applied voltage flows through the primary side of the transformer 34. In the primary circuit of the center tap transformer 34, the intermittent DC output voltage is converted into a high-frequency AC through a reflux diode 33. Capacitor 32
Absorbs a surge voltage caused by the excitation energy of the center tap transformer 34 generated when the transistor 35 is turned off.

The transformers 14, 24,
In the secondary circuit of No. 34, the high-frequency alternating currents are full-wave rectified by the diodes 2 and 3. This rectified output is smoothed by the reactor 4 and the capacitor 5 and output to the output terminals P and N. Reactor 4 has transformer 1
The secondary-side synthesized voltages 4, 24 and 34 are applied, and a discontinuous current flows according to the applied voltage.
It becomes as shown in.

The three-phase AC input current is a composite value of the input currents of the single-phase forward converters 10, 20, and 30, and the Nth harmonic of the third harmonic generated in the line voltage is removed. You.

As described above, according to the three-phase rectifier 1 of the embodiment of the present invention, the outputs of the input / output insulated single-phase forward converters 10, 20, and 30 are connected in series, and the same control is performed. The current of the reactor 4 is operated in the discontinuous mode by controlling the current in the discontinuous mode, and the current corresponding to the input voltage instantaneous value of each of the single-phase forward converters 10, 20, 30 is supplied. Can be performed. In addition, each single-phase forward converter 10, 2
Since only one conversion device is required for each of the 0 and 30 conversion devices, the control method is simplified, and a simple main circuit configuration and a high power factor of a three-phase AC input can be achieved.

[0039]

According to the three-phase rectifier of the present invention, the outputs of three sets of input / output insulated single-phase forward converters are connected in series, controlled by the same control signal, and the current of the filter reactor is discontinuous. By operating in the mode and supplying a current corresponding to the instantaneous value of the input voltage of each single-phase forward converter, it is possible to convert the three-phase AC input current 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 main circuit configuration and a high power factor of a 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, 3 Diode 4 Reactor 5 Capacitor 6 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

 ────────────────────────────────────────────────── ─── 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 CA12 CB01 CC01 CC05 DA02 DA04 DB01 DC05 5H730 AA18 AS01 BB23 BB57 BB82 BB88 CC02 CC05 DD02 DD42 EE02 EE08 EE76 FD01 FF02 FG05

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 single-phase full-wave diode rectifier output, connect the primary winding end of the center tap transformer to the collector of a 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. Connect between the outputs and start and end the secondary winding of the center tap transformer. Three sets of single-phase forward converters having two terminals as outputs are provided, and each AC input stage of each single-phase forward converter is delta-connected between the three-phase AC input lines. The output connects the center tap transformer secondary winding end of the first single-phase forward converter to the center tap transformer secondary winding start of the second single-phase forward converter, and the center tap of the second single-phase forward converter The secondary winding end of the transformer is connected to the center tap transformer secondary winding start of the third single-phase forward converter, so that three center tap transformers are connected in series as a whole, and the center of the first single-phase forward converter is connected. Connect the start of the secondary winding of the tap transformer to the anode of the output rectifier diode. The other end of this filter reactor is connected to the positive side of the total DC output, and the end of the secondary tap of the center tap transformer of the third single-phase forward converter is connected to the flywheel diode. Connected to the anode, the connection point is connected to the negative side of the total DC output, the cathode of this flywheel diode is connected to the cathode of the output rectifier diode, and commonly connected to the total DC output stage of each single-phase forward converter A control circuit commonly connected to each of the drive circuits 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.