JP2003235266A - Three-phase full-wave rectifier - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a three-phase full-wave rectifier having an open-phase detecting circuit capable of detecting an open-phase state in a primary side of a step-down transformer in a three-phase alternating current. <P>SOLUTION: The three-phase full-wave rectifier is provided with a three-phase full-wave rectifier circuit for supplying alternating power obtained by full-wave- rectifying a three-phase alternating current input, a control circuit for controlling this, an open-phase detecting circuit for detecting the open-phase to provide a signal to the control circuit. The open-phase detecting circuit is provided with a three-phase bridge circuit 50 for full-wave-rectifying the three-phase alternating input, a voltage detecting circuit 80 for generating an energizing voltage when the voltage between output terminals of the circuit 50 is lower than the open-phase detecting voltage, a capacitor charging circuit 82 consisting of a resistor 40 having a charging time constant larger than a cycle of the three-phase alternating current and a capacitor 42 to charge the output of the circuit 50, and a photocoupler 44 for generating a signal indicating abnormality if the three-phase alternating current has an open-phase. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention supplies a load with a DC power generated by full-wave rectifying the three-phase AC input, which has a function of detecting a missing phase of the input three-phase AC voltage. It relates to a three-phase full-wave rectifier.

[0002]

2. Description of the Related Art As a three-phase full-wave rectifying device that receives a three-phase AC input and supplies a DC voltage higher than the three-phase AC voltage to a load, there is a structure shown in FIG. The three-phase AC input terminals 1U, 1V, and 1W are three-phase AC input terminals that receive a three-phase AC input (voltage), and the phase line 2
U, 2V and 2W are connected respectively. Phase line 2U,
2V and 2W are connected to the three-phase full-wave rectifier circuit 6 via the circuit breaker 3 and the boosting inductors 5U, 5V, and 5W, respectively. Further, X capacitors C1, C2 and C3 are inserted between the phase lines 2U, 2V and 2W, respectively.

Here, the three-phase full-wave rectifier circuit 6 is a switching semiconductor element Q1, such as an IGBT (insulated gate bipolar transistor) or a MOSFET (metal / oxide film / semiconductor field effect transistor) connected to a three-phase bridge. It is composed of Q2, Q3, Q4, Q5 and Q6. In addition, switching semiconductor elements Q1, Q2, Q
3, Q4, Q5 and Q6 have diodes D1 and D, respectively.
2, D3, D4, D5 and D6 are connected in parallel in the reverse direction with respect to the polarity.

Further, the switching semiconductor elements Q1, Q
2, Q3, Q4, Q5 and Q6 have zero voltage switching (Z
Capacitors C4, C5, C to enable VS)
6, C7, C8 and C9 are connected in parallel. The switching semiconductor elements Q1 to Q1 are connected by the capacitors C4 to C9.
Power loss at turn-off of Q6 is greatly reduced.

However, the capacitors C4 to C9 are
When the switching semiconductor elements Q1 to Q6 are turned on, they act to increase their turn-on loss. Therefore, the inductance element 11 is connected to the capacitors C4 to
It is provided between the output terminals of the three-phase full-wave rectifier circuit 6 in order to resonate with any of C9. By turning on the switching semiconductor elements Q7 and Q8 for a certain time immediately before the switching semiconductor elements Q1 to Q6 are turned on, the inductance element 11 resonates with any set of the capacitors C4 to C9, and the switching semiconductor elements Q1 to Q6, Capacitor C4 connected in parallel with this switching semiconductor element
The energy charged in C9 is transferred and accumulated, and the switching semiconductor element is caused to turn on zero voltage.

The switching semiconductor elements Q7 and Q8 are
An inductance element 11 is sandwiched between the positive common line 6A and the negative common line 6B of the three-phase full-wave rectifier circuit 6 and inserted in series. Further, the switching semiconductor element Q7
Diodes D7 and D8 are reversely connected in parallel to Q8 and Q8, respectively. Further, the capacitor 10 is connected in parallel to the switching semiconductor element Q8. A diode D0 for preventing backflow is inserted in the positive common line 6A, and a smoothing capacitor 7 is inserted between the positive common line 6A and the negative common line 6B.

The control circuit 9 detects the voltage between the positive electrode of the capacitor and the negative common line 6B, and the current detection circuit 4 (composed of current sensors 4U, 4V and 4W) detects each phase line. Current flowing through the switching semiconductor elements Q1 to Q1 based on these detection results.
Each of the Q6 performs high-frequency switching during a half cycle (π) of the corresponding phase voltage, and controls the drive circuit 10 that turns on / off the switching semiconductor elements Q1 to Q6.

At this time, the open-phase detection circuit 60 detects that power is no longer supplied to any of the phase lines 2U, 2V, 2W. When the phase loss occurs, the three-phase full-wave rectifier circuit 6 cannot supply the required direct current output of electric power, which has an adverse effect on the load. Need to be stopped.

The phase loss detection circuit 60 will be described below with reference to the drawings. FIG. 6 is a block diagram showing the configuration of a conventional open phase detection circuit 60. The voltage detection circuit 110 has a phase line 2U.
And a single-phase alternating current of 2V is rectified to detect the voltage value of the peak-charged DC voltage. Similarly, the voltage detection circuits 120 and 130 detect the peak-charged voltage values of the single-phase alternating currents of the phase lines 2V and 2W and the phase lines 2W and 2U.

Since the voltage detection circuits 110, 120 and 130 have the same configuration, the configuration will be described using the voltage detection circuit 110. Diode 10 connected to single phase bridge
1 to 104 rectify the AC voltage supplied from the phase lines 2U and 2V, and the capacitor 105 is peak-charged with the rectified DC voltage. The resistors 106 and 107 divide the peak-charged voltage of the capacitor 105. Here, the resistance values of the resistors 106 and 107 are
It is set by the standard value of the reverse voltage of the Zener diode 108, which has a set value for detecting the accumulated voltage peak-charged in the capacitor 105 (detecting whether the voltage has dropped below a predetermined voltage value). The set value is lower than the voltage peak-filled in the capacitor 105 in the normal case,
The voltage is set higher than the peak voltage of the capacitor 105 when the phase is lost.

When the divided voltage exceeds the set value (standard value of the reverse voltage), the Zener diode 108 conducts to pass a current to charge the capacitor 109. As a result, the voltage detection circuit 101 turns on the photocoupler 121 at the next stage and transmits a signal. Similarly,
The voltage detection circuits 110 and 120 are connected to the phase lines 2V and 2
W, phase line 2W, rectify the single-phase alternating current of 2U,
The predetermined voltage is output.

Next, the diode of the photocoupler 121 has its anode connected to the anode of the Zener diode 8 in the voltage detection circuit 110 and its cathode connected to the collector of the transistor of the photocoupler 122. The emitter of the transistor of the photocoupler 122 is connected to the anode of the diode 104 in the voltage detection circuit 110. The anode of the diode of the photocoupler 122 is connected to the anode of the Zener diode 8 in the voltage detection circuit 120, and the cathode is connected to the collector of the transistor of the photocoupler 123.

The emitter of the transistor of the photocoupler 123 is the diode 104 in the voltage detection circuit 120.
Connected to the anode of. The anode of the diode of the photocoupler 123 is connected to the anode of the Zener diode 108 in the voltage detection circuit 130, and the cathode is connected to the anode of the diode 104 in the voltage detection circuit 130. Further, the transistor of the photocoupler 121 outputs the open phase detection signal to the control circuit 9 via the output terminals T1 and T2.

With the above connection, the photocoupler 121
The transistors of the photocoupler 121 are in the ON state only when all of the diodes (light emitting diodes) 123 to 123 are in the light emitting state. For this reason,
When a phase loss occurs in the input 3-phase AC input, the voltage value charged in the capacitor 105 decreases, the reverse voltage of the Zener diode 108 does not reach the standard value, and the output terminals T1 and T2 are opened. It becomes a state. The control circuit 9 detects the open state between the output terminals T1 and T2, and when detected, stops the operation of the three-phase full-wave rectifier.

[0015]

However, the above-described conventional open-phase detection circuit 60 is different from each voltage detection circuit 11 described above.
Only the peak value of the DC voltage of the voltage of the capacitors 105 of 0, 120 and 130 is detected. Therefore, when the input voltage is distorted, the conventional phase loss detection circuit 60 may not be able to detect the phase loss.

Normally, a three-phase full-wave rectifier circuit has a high voltage (660
It receives a 3-phase AC input of 0V) and uses it as a low-voltage (for example, 200V or 400V) 3-phase AC input via a step-down transformer. Here, the circuit for stepping down the voltage has the configuration shown in FIG. FIG. 4 is a conceptual diagram showing a circuit configuration around the step-down transformer G. The high-voltage three-phase AC voltage input from the voltage source K is converted into Y-Δ (star-
A step-down transformer G, which is a Delta-connected transformer, is stepping down.

The phase lines R ', S', T'connect the voltage source K and the primary side of the step-down transformer G, and the phase lines R, S ', T'
S and T connect the secondary side of the step-down transformer G and the three-phase AC input terminals 1U, 1V and 1W, respectively. It is considered that the phase loss occurs on the primary side and the secondary side of the step-down transformer G. If any of the secondary phase lines R, S, T of the step-down transformer G fails (for example, if the connection is disconnected), the step-down transformer G is completely disconnected from the disconnected phase line. Power will not be supplied from.

Therefore, at the three-phase AC input terminals corresponding to the phase line in which the open phase has occurred, the resistors RRS, RST, and RTR divide the AC voltage of the other phase lines that are not open phase. Only voltage is generated. Therefore, in the open-phase detection circuit 60, the capacitor 105 of the voltage detection circuit corresponding to the open-phase AC voltage is not charged with a voltage enough to make the Zener diode 108 conductive, and the output terminals T1 and T2 are turned off. The state is entered and the open phase can be detected.

On the other hand, when a failure occurs in any of the primary side phase lines R ', S', T'of the step-down transformer G (for example, when the connection is disconnected), unlike the case of the secondary side. ,
Saturation of the magnetic flux of the transformer occurs due to the load condition of the three phases, waveform distortion occurs, and the phase line R that supplies the three-phase AC input,
A voltage having a large peak value is generated in S and T. At this time,
In the open-phase detection circuit 100, the voltage for making the Zener diode 108 conductive is peak-charged in the capacitor 105 of the voltage detection circuit corresponding to the open-phase AC input, so that the output terminals T1 and T2 are turned on. In some cases, the open phase may not be detected even though the open phase has occurred.

The present invention has been made under such a background, and a three-phase full-wave rectifier having an open phase detection circuit capable of detecting open phase even in the open phase state on the primary side of a step-down transformer. To provide.

[0021]

SUMMARY OF THE INVENTION A three-phase full-wave rectifying device of the present invention is a control type three-phase full-wave rectifying circuit (for example, a full-wave rectifying a three-phase AC input to supply adjusted DC power to a load). Three
Phase full-wave rectifier circuit 6), a control circuit (for example, control circuit 9) for controlling the control type three-phase full-wave rectifier circuit, and a signal to the control circuit for detecting a power failure and a missing phase of the three-phase AC input. Open-phase detection circuit (for example, open-phase circuit 20, 20A, 20
B) in a three-phase full-wave rectifier, the open-phase detection circuit includes a three-phase full-wave rectifier circuit (for example, a three-phase bridge circuit 50) that full-wave rectifies a three-phase AC input, and the three-phase A set voltage detection circuit (e.g., voltage) that generates an energizing voltage when the voltage between the output terminals of the full-wave rectifier circuit (for example, between the positive common line 30A and the negative common line 30B) becomes lower than the set voltage. Detection circuit 80, 80 '), a resistor (e.g., resistor 40) and a capacitor (e.g., capacitor 4) exhibiting a charging time constant larger than the cycle of the three-phase AC input.
2) consists of a capacitor charging circuit (for example, a capacitor charging circuit 82) that charges the output of the three-phase full-wave rectifier circuit with the charging time constant, and the bias voltage from the set voltage detection circuit. And a capacitor discharge circuit (for example, the capacitor discharge circuit 81) that discharges the capacitor of the capacitor charge circuit and a certain voltage value of the voltage of the capacitor charge circuit (for example, the voltage at the connection point L is the zener diode 43). When the voltage is smaller than the voltage value of the reverse voltage for making the conduction state, the three-phase AC input is in the open phase state and the voltage of the capacitor charging circuit is at a certain voltage (for example, the voltage at the connection point L makes the Zener diode 43 conductive). Signal voltage for generating a detection signal indicating that the three-phase AC input is in a normal state when the voltage value of the reverse voltage to be applied is exceeded. Circuit (for example, photo-coupler 44)
It is characterized by having and.

In the three-phase full-wave rectification device of the present invention, the open-phase detection circuit is a constant voltage element which becomes non-conductive when the voltage between the output terminals of the three-phase full-wave rectification circuit becomes smaller than the set voltage. A resistor connected in series with the constant voltage element, and a semiconductor switch element that is turned off when the control terminal is connected to a connection point between the resistor and the constant voltage element and the constant voltage element becomes non-conductive A set voltage detection circuit is provided, and when the voltage between the output terminals is lower than the set voltage, the semiconductor switch element is turned off, whereby the capacitor discharge circuit is turned on to discharge the capacitor of the capacitor charge circuit, The signal generation circuit is turned off.

In the three-phase full-wave rectifier of the present invention, the open-phase detection circuit generates an ON signal when the voltage between the output terminals exceeds the reference voltage of the reference source, and the comparison circuit from the comparison circuit. The capacitor discharge circuit is provided with the constant voltage detection circuit including a semiconductor switch element that is turned on by an on signal, and the semiconductor switch element is turned off when the voltage between the output terminals becomes lower than a reference voltage of a reference source. Turns on to discharge the capacitor of the capacitor charging circuit and turn off the signal generating circuit.

A hysteresis circuit (for example, the hysteresis circuit 8) that gives hysteresis to the set voltage detection circuit.
5) are connected to the output side of the signal generation circuit and the input side of the set voltage detection circuit, respectively.

[0025]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing a configuration example of a three-phase full-wave rectifier according to an embodiment of the present invention. The other components similar to those of the conventional example are designated by the same reference numerals, and the description of the configuration is omitted. In this figure,
The difference from the configuration of the three-phase full-wave rectifier in the conventional example is that
That is, instead of the phase loss detection circuit 100, the phase loss detection circuit 20 is newly used for phase loss detection. Here, the term “phase loss of the three-phase AC input” includes a power failure of the three-phase AC input. Hereinafter, the phase loss detection circuit 20 is assumed to be the phase loss detection circuit having the configuration shown in FIG. 2 according to the present invention.

The open-phase detection circuit 20 of the present invention is configured to open the phase on the primary side of the step-down transformer G, and phase lines 2U of all three phases,
When a large voltage is generated in 2V and 2W, the phase difference of the voltage generated in each phase line is not (2π / 3) in the normal state where there is no open phase, that is, it is not 120 °, but the phase is slightly shifted. The fact that the waveform is close to the phase is used to detect the open phase. That is, in the open-phase detection circuit of the three-phase full-wave rectifier of the present invention, the three-phase full-wave rectifier performs three-phase full-wave rectification, so that the timing of the voltage close to “0” is surely present, and the certainty is ensured. It has a circuit configuration for detecting the open phase state.

The open-phase detection circuit 20 used in the three-phase full-wave rectifier of the present invention will be described with reference to FIG. FIG. 2 is a conceptual diagram of a circuit showing a configuration example of the open phase detection circuit 20.
The diodes 24 to 29 are bridge-connected for full-wave rectification of a three-phase AC voltage to form a three-phase bridge circuit 50. A phase line 2U is connected via a resistor 21 to a connection point between the anode of the diode 24 and a cathode of the diode 27, and a phase line 2V is connected via a resistor 22 to a connection point between the anode of the diode 25 and the cathode of the diode 28. The phase line 2U is connected to the connection point between the anode of the diode 26 and the cathode of the diode 29 via the resistor 23.

The resistors 31 and 32 are the positive common line 30A and the negative common line 30B of the three-phase bridge circuit 50.
And are connected in series between and. The Zener diode 33 has a cathode connected to the connection point J of the resistors 31 and 32, and an anode connected to the negative common line 30B via the resistor 34. The transistor 36 is
It is an npn type bipolar transistor whose emitter is connected to the negative common line 30B, whose base is connected to the anode of the Zener diode 33, and whose collector is the resistor 47.
Is connected to the positive common line 30A via.

The Zener diode 37 has a cathode connected to the collector of the transistor 36 and an anode connected to the negative common line 30B via the resistor 38.
Here, the resistors 31, 32, 34, 38, 47, the Zener diodes 33, 37, the transistor 36, and the capacitor 35 constitute a voltage detection circuit 80 that detects the voltage value at the connection point J. .

The transistor 39 is an npn-type bipolar transistor whose emitter is connected to the negative common line 30B, whose base is connected to the anode of the Zener diode 37 and whose collector is connected in series.
It is connected to the positive common line 30A via 41.
The resistor 41 and the transistor 39 constitute a capacitor discharge circuit 81 that discharges the electric charge accumulated in the capacitor 42 described later.

The capacitor 42 is inserted between the connection point L of the resistors 40 and 41 and the negative common line 30B and is used as a capacitor for charging whose time constant is determined by the resistor 40. To be Resistor 40 and capacitor 42
As described above, the capacitor charging circuit 82 having a predetermined time constant that makes the Zener diode 43 conductive is configured. The Zener diode 43 is provided between the connection point L and the negative common line 30B between the photo coupler 4 and
4 diode is inserted in series.

Next, with reference to FIGS. 1 and 2, an operation example of the open-phase detection circuit 20 in the three-phase full-wave rectifier circuit of one embodiment will be described. As long as there is no open phase in the three-phase AC voltage, the voltage value at the connection point J always exceeds the reverse voltage of the Zener diode 33 and becomes conductive, and the voltage charged in the capacitor 35 turns on the transistor 36. ing.

As a result, the voltage at the connection point K is not so high as to make the Zener diode 37 conductive, and the transistor 39 is in the OFF state.
2 is charged through the resistor 40, and makes the Zener diode 43 in a conductive state.

As a result, the transistor of the photocoupler 44 is turned on, and the output terminals T10 and T11 are in a conductive state (detection signal in a state where there is no open phase). When the control circuit 9 detects that the output terminals T10 and T11 are in the conducting state, the control circuit 9 determines that the phase is not lost, and controls the full-wave rectification circuit 6 in the normal state.

Here, for example, if the AC voltage of the phase line S'has an open phase on the primary side, a voltage close to "0 V" in the phase of 210 ° and 30 ° of the next cycle is a three-phase bridge circuit 50. Is output from. At this time, the connection point J
Voltage of the connection point J decreases (detection voltage value)
Becomes lower than the voltage for conducting the Zener diode 33, the supply of the current from the Zener diode 33 is stopped, and the voltage accumulated in the capacitor 35 becomes the resistance 34.
Is discharged to the negative common line 30B via, and the base voltage of the transistor 36 drops to be turned off. Here, the voltage division ratio of the resistance values of the resistor 31 and the resistor 32 is equal to that of the resistor 3
The voltage at the connection point J between 1 and the resistor 32 is set to a voltage value that turns on the transistor 36 via the Zener diode 33.

That is, the open phase detection voltage for detecting open phase is set slightly lower than 3 ^1/2/2 of the peak value of the minimum input voltage. (Eg 5-10% of each voltage).

At this time, the voltage division ratio of the resistance values of the resistors 31 and 32 is set such that the open phase detection voltage is divided at the connection point J and the transistor 36 becomes a voltage value (detection voltage value) that is turned on. Set to. Therefore, the detected voltage value is set to a voltage value obtained by adding the value of the reverse voltage applied to the cathode at which the selected Zener diode 33 becomes conductive and the base voltage at which the transistor 36 is turned on. , The resistances of the resistors 31 and 32 are set and obtained. With the above structure, the transistor 39 is turned on and the charge accumulated in the capacitor 42 is discharged.

Then, the transistor 36 is turned on when the Zener diode 37 becomes conductive and the voltage of the base rises, and the charge accumulated in the capacitor 42 is discharged. Therefore, the Zener diode 43
Changes from the conducting state to the non-conducting state, power is not supplied to the diode of the photocoupler 44, and the transistor of the photocoupler 44 is turned off.

Then, between the output terminals T10 and T11, the transistor of the photocoupler 44 is turned off so that it is in a non-conducting state (becomes a detection signal indicating that the phase is open). As a result, the control circuit 9 detects that a phase loss has occurred, and therefore the three-phase full-wave rectifying device is stopped until it returns to the normal state (a state in which the output terminals T10 and T11 are conductive). Here, the resistance value of the resistor 40 and the capacitance of the capacitor 42 are the same as those of the capacitor 4
2 (the reverse voltage applied to the cathode of the Zener diode 43) is stored in the Zener diode 4
The time constant until the voltage value of the reverse voltage in which 3 becomes conductive is set to be sufficiently larger than the cycle of the three-phase AC voltage.

As a result, as long as one of the three-phase AC inputs is in the open phase state, the voltage charged in the capacitor 42 is always the open phase AC voltage before the Zener diode 43 becomes conductive. 3 in phase timing
The voltage on the positive common line 30A of the phase bridge circuit 50 drops and the transistor 39 discharges the charge on the capacitor 42. Therefore, as long as one of the three-phase AC voltages is in the open phase state, the transistor of the photocoupler 44 is in the off state between the output terminals T10 and T11 to be in the non-conductive state.

The Zener diode 3 shown in FIG.
3 and the resistor 34 may be replaced with the comparison circuit 45 and the reference voltage source 46 to form the open phase detection circuit 20A shown in FIG. As a result, the resistors 31, 32, 38, 47, the reference voltage source 46, the comparison circuit 45, the Zener diode 37,
The transistor 36 and the capacitor 35 form a voltage detection circuit 80 ′ that detects the voltage value at the connection point J. In the open phase detection circuit 20A, the reference voltage source 4
The voltage value output by 6 is the detected voltage value for detecting the open phase. In the comparison circuit 45, the power supply terminal is connected to the positive common line 30A via the resistor 90, the ground terminal is connected to the negative common line 30B, and the constant voltage diode 91 is connected in parallel between the power supply terminal and the ground terminal. It is connected.

Then, when the voltage value at the connection point J becomes lower than the detected voltage value, the comparison circuit 45 sets the output to the "L" level and turns off the transistor 36. here,
As described above, the detected voltage value is a voltage value obtained by dividing the open phase detection voltage for detecting the open phase by the resistors 31 and 32 with a predetermined voltage division ratio. Other configurations and operations of the open phase detection circuit 20A shown in FIG. 3 are similar to those of the open phase detection circuit 20 shown in FIG.

The three-phase full-wave rectifier of the present invention described above is
Instead of performing the single-phase full-wave rectification as in the conventional example and detecting the open phase by the voltage value that peak-charges the capacitor, in the open phase detection circuit 20, the three-phase AC input by the three-phase bridge circuit 50 is input. Since the voltage is three-phase full-wave rectified and the resulting change in the rectified voltage is detected by the voltage detection circuit 80, the detection speed is high. In addition, when a phase loss occurs on the primary side of the step-down transformer G and a high abnormal voltage occurs on all phase lines on the secondary side, the rectified voltage is significantly reduced at the timing of the phase of the AC voltage that is missing. By using the phenomenon described above, the voltage detection circuit 80 can detect the open phase by comparing the voltage value when the rectified voltage is decreased due to the open phase with the normal value of the rectified voltage.

Although one embodiment of the present invention has been described in detail above with reference to the drawings, the specific structure is not limited to this embodiment, and design changes within the scope not departing from the gist of the present invention. Even so, it is included in the present invention. For example, as another embodiment, a three-phase full-wave rectifier circuit may be configured by using the open-phase detection circuit 20B shown in FIG. 5 provided with the hysteresis circuit 85 in the open-phase detection circuit 20 of FIG. FIG. 5 is a conceptual diagram showing a configuration example of the open-phase detection circuit 20B used in the three-phase full-wave rectification circuit of another embodiment. The phase loss detection circuit 20B in the following description is the phase loss detection circuit having the configuration shown in FIG.

The hysteresis circuit 85 is a voltage detecting circuit 8
The voltage division ratio determined by the resistance 31 and the resistance 32 at 0 is compared with the resistance 56 connected via the diode 53,
It is changed by a combined resistance (parallel connection) formed by the resistance 31. As a result, the open-phase detection circuit 20B detects the open-phase of the AC voltage and stops the three-phase full-wave rectifier (stop voltage), and the start-up voltage (start-up for eliminating the open-phase and starting up). Voltage), that is,
There will be hysteresis to lower the stop voltage and increase the start voltage.

As a constitution, the hysteresis circuit 85 which gives a hysteresis to the above-mentioned stop voltage and start-up voltage,
The photocoupler 44 that outputs a detection signal and the cathode of the diode 53 are connected to the connection point J (the input side of the voltage detection circuit 80). The photocoupler 51 of the hysteresis circuit 85 is connected to the photocoupler 44 and the negative common line 3
It is inserted between 0B. That is, the diode of the photocoupler 44 and the diode of the photocoupler 51 are connected in series.

In the transistor of the photocoupler 51, the emitter is connected to the negative common line 30B and the collector is connected to the positive common line 30A via the resistor 52. The Zener diode 54 has a cathode connected to the collector of the transistor of the photocoupler 51 and an anode connected to the base of the transistor 55. The transistor 55 has an emitter connected to the negative common line 30B and a positive common line 30A via a resistor 56. The diode 53 has an anode connected to the collector of the transistor 55 and a cathode connected to the cathode (connection point J) of the Zener diode 33.

The operation of the open phase detection circuit 20B related to the hysteresis circuit 85 will be described below. The operation of the other circuit parts is the same as that of the open-phase detection circuit 20 in the embodiment, and thus the description thereof is omitted. When there is no open phase in the input three-phase AC input (when the three-phase full-wave rectifier is operating normally), the transistor 36 is in the ON state and the transistor 39 is in the OFF state. A reverse voltage, which is conductive, is applied to the photo coupler 44 and the photo coupler 51.
Driving power is supplied to both of the diodes (light emitting diodes).

As a result, the transistors of both the photocoupler 44 and the photocoupler 51 are conductive. Therefore, the output terminal T10 and the output terminal T11 are in a conductive state, and are output as a detection signal indicating that the phase is not open. In addition, the transistor 55 is in the off state because the reverse voltage that makes it conductive is not applied to the zener diode 54, and therefore the base current that makes it on is not supplied.

At this time, since a current flows from the resistor 56 to the connection point J via the diode 53, the resistor 31 and the resistor 5 are connected.
6 forms a combined resistance. As a result, the resistance value of the resistor 31 becomes a combined resistance with the resistance 56, so that the resistance value of the resistor 31 is apparently lowered, and the resistance 31 and the resistor 3 are combined.
The voltage at the connection point J is set to be higher than in the case where the resistance ratio is only 2.

On the other hand, when a phase loss occurs in the input three-phase AC input, the voltage at the connection point J decreases, and the reverse voltage for making the zener diode 33 conductive is not applied. The base current in the state is no longer supplied, and the transistor 36 is turned off.
Then, the Zener diode 37 becomes conductive by applying a reverse voltage to the cathode so that the Zener diode 37 becomes conductive, and applies a drive current to the base of the transistor 39.

As a result, the transistor 39 is turned on by applying the drive current to the base, and the electric charge accumulated in the capacitor 42 is discharged. As a result,
The Zener diode 43 is in a non-conducting state because the reverse voltage which is in a conducting state is not applied to the cathode. Then, the drive current is not supplied to the diodes of both the photo coupler 44 and the photo coupler 51, and the transistors of both the photo coupler 44 and the photo coupler 51 are turned off. Therefore, the output terminal T10 and the output terminal T1
Between 1 and 1, it is in a non-conducting state and is output as a detection signal indicating that it is in the open phase state.

As a result, the transistor 55 is turned on because the reverse voltage that turns it on is applied to the zener diode 54, and the base current that turns on is supplied. At this time, the current flowing through the resistor 56 flows through the transistor 55 into the negative common line 30B. Therefore, no current flows from the resistor 56 to the connection point J via the diode 53,
The resistance 31 and the resistance 56 do not form a combined resistance. As a result, the resistance value of the resistor 31 does not become a combined resistance with the resistor 56, so that the resistance value of the resistor 31 does not change, and the resistance ratio between the resistors 31 and 32 is greater than that when the combined resistance is formed. Thus, the voltage at the connection point J is set low.

As described above, the three-phase full-wave rectifier according to another embodiment of the present invention has two set values of the start voltage and the stop voltage as the detection voltage, in addition to the effect of the one embodiment already described. By providing the hysteresis circuit 85 with different values of the start voltage and the stop voltage, and setting a stop voltage lower than the start voltage, it is possible to add hysteresis to the start and stop operations. For,
After the open-phase condition is detected and the system is temporarily stopped, the open-phase disappears and the three-phase AC voltage is supplied normally, and the rectified current is restarted when it stabilizes. Starting and stopping are not repeated in small intervals between values, and stable operation can be performed.

[0055]

According to the three-phase full-wave rectifier of the present invention,
As in the conventional example, full-wave rectification is performed for each single phase, the rectified voltage is used to charge the capacitor, and the open phase is not detected by the voltage value of the average voltage during the predetermined period. In order to detect the rectified voltage resulting from the three-phase full-wave rectification by the three-phase full-wave rectification circuit, that is, the change in the DC component of the three-phase AC input, a phase loss occurs on the primary side of the step-down transformer G. Even if a high abnormal voltage occurs on all the secondary side phase lines, there is always a time when the rectified current drops significantly at the timing of the phase of the open phase AC voltage, so compare it with the normal value. Thereby, it becomes possible to detect the open phase.
Therefore, the phase loss can be detected with certainty, and the phase loss detection speed can be significantly increased.

[Brief description of drawings]

FIG. 1 is a diagram showing an embodiment (and a conventional example) of the present invention;
It is a block diagram showing an example of composition of a phase full wave rectifier.

FIG. 2 is an open phase detection circuit 2 according to an embodiment of the present invention.
It is a conceptual diagram of the circuit which shows the structural example of 0.

FIG. 3 is a diagram illustrating an open phase detection circuit 2 according to an embodiment of the present invention.
It is a conceptual diagram of a circuit showing a configuration example of 0A.

FIG. 4 is a conceptual diagram showing a circuit configuration around a step-down transformer G that supplies a three-phase AC voltage to a three-phase full-wave rectifier.

FIG. 5 is a conceptual diagram of a circuit showing a configuration example of an open phase detection circuit 20B according to another embodiment of the present invention.

FIG. 6 is a conceptual diagram of a circuit showing the configuration of a phase loss detection circuit 60 in a conventional three-phase full-wave rectifier.

[Explanation of symbols]

3 Circuit breaker 6 Three-phase full-wave rectifier circuit 1U, 1V, 1W AC input terminals 2U, 2V, 2W Phase lines 4U, 4V, 4W Current detection inductors 6A, 30A Positive common line 6B, 30B Negative common line 7, 35,42 Capacitor 8 Load 9 Control circuit 10 Drive circuit 11 Inductors 20, 20A, 20B, 60 Open phase detection circuits 21, 22, 23, 31, 32, 34 Resistors 24, 25, 26, 27, 28, 29, 53 Diodes 33, 37, 43, 54 Zener diodes 36, 39, 55 Transistors 38, 40, 41, 47, 52, 56 Resistors 44, 51 Photocoupler 45 Comparison circuit 46 Reference voltage source 50 Three-phase bridge circuit 80 Voltage detection circuit 81 Capacitor discharging circuit 82 Capacitor charging circuit 85 Hysteresis circuit C1, C2, C3, C4, C5, C6 7, C8, C
9 Capacitors D0, D1, D2, D3, D4, D5, D6, D7, D
8 Diodes Q1, Q2, Q3, Q4, Q5, Q6, Q7, Q8 Switching semiconductor elements T10, T11 Output terminals

   ─────────────────────────────────────────────────── ─── Continued front page    (71) Applicant 000106276             Sanken Electric Co., Ltd.             3-6 Kitano, Niiza City, Saitama Prefecture (72) Inventor Yoshio Suzuki             Oriji, 1-1-18 Takada, Toshima-ku, Tokyo             N Denki Co., Ltd. (72) Inventor Katsumi Kogure             Oriji, 1-1-18 Takada, Toshima-ku, Tokyo             N Denki Co., Ltd. (72) Inventor Masatoshi Murase             3-4-1 Shibaura, Minato-ku, Tokyo Co., Ltd.             Within NTT Facilities (72) Inventor Kengo Machida             2-2-1 Otemachi, Chiyoda-ku, Tokyo New             Dengen Kogyo Co., Ltd. (72) Inventor Yasuya Murakawa             Sanke, 3-6 Kitano, Niiza City, Saitama Prefecture             N Denki Co., Ltd. F-term (reference) 5H006 AA04 CA01 CA07 CA12 CA13                       CB01 CC08 DB02 DC04 DC05                       FA04

Claims (4)

[Claims] 1. A three-phase full-wave rectifying circuit for full-wave rectifying a three-phase AC input to supply adjusted DC power to a load, a control circuit for controlling the three-phase full-wave rectifying circuit, and a three-phase AC. In a three-phase full-wave rectifying device that includes an open-phase detection circuit that detects an input open-phase and gives a signal to the control circuit, the open-phase detection circuit is a three-phase full-wave rectifier that full-wave rectifies a three-phase AC input. Wave rectifier circuit, a set voltage detection circuit that generates an energizing voltage when the voltage between the output terminals of the three-phase full-wave rectifier circuit becomes lower than the set voltage, and during charging that is greater than the cycle of the three-phase AC input. A capacitor charging circuit configured to charge the output of the three-phase full-wave rectifier circuit with the charging time constant, which is composed of a resistor and a capacitor exhibiting a constant, and operates by receiving the bias voltage from the set voltage detection circuit, A capacitor for discharging the capacitor of the capacitor charging circuit. When the voltage of the capacitor discharge circuit and the voltage of the capacitor charging circuit are smaller than a certain voltage value, the three-phase AC input is in an open phase state, and when the voltage of the capacitor charging circuit exceeds a certain voltage, the three-phase AC input is normal. A three-phase full-wave rectifying device, comprising: a signal generating circuit that generates a detection signal indicating that the state is in a state. 2. The set voltage detection circuit includes a constant voltage element which becomes non-conductive when a voltage between output terminals of the three-phase full-wave rectifier circuit becomes lower than a set voltage, and a control terminal connected to the constant voltage element. A semiconductor switch element that is turned off when the constant voltage element becomes non-conductive by being connected, and the semiconductor switch element is turned off when the voltage between the output terminals is lower than the set voltage. The three-phase full-wave rectifier according to claim 1, wherein the capacitor discharging circuit is turned on to discharge the capacitor of the capacitor charging circuit, and the signal generating circuit is turned off. 3. The set voltage detection circuit includes a comparison circuit that generates an ON signal when the voltage between the output terminals exceeds a reference voltage of a reference source, and a semiconductor switch element that is turned ON by the ON signal from the comparison circuit. The semiconductor switch element is turned off when the voltage between the output terminals becomes lower than the reference voltage of the reference source, whereby the capacitor discharge circuit is turned on to discharge the capacitor of the capacitor charge circuit, The three-phase full-wave rectifier according to claim 1, wherein the signal generating circuit is turned off. 4. A hysteresis circuit for giving a hysteresis to the set voltage detection circuit is connected to an output side of the signal generation circuit and an input side of the set voltage detection circuit, respectively. The three-phase full-wave rectifier according to any one of 1.