JP3096236B2 - Power supply - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power supply that can be used regardless of whether two AC voltages having different values are supplied.
The present invention relates to an input voltage-compatible power supply device.

[0002]

2. Description of the Related Art A two-input voltage type power supply is used as a power supply for welding, a power supply for a cutting machine, an uninterruptible power supply, a switching power supply, and the like. Conventionally, 2
2. Description of the Related Art As an input voltage compatible power supply, for example, a welding power supply, there is one disclosed in Japanese Utility Model Publication No. 3-855. A high voltage (for example, 200
When the AC power supply V) is supplied, in this welding power supply device, a high-voltage AC voltage is full-wave rectified by a rectifier, smoothed by two series-connected smoothing capacitors, and supplied to the inverter. . Low voltage (eg 1
In the case where an AC voltage of (00 V) is supplied to the welding power supply, the rectifier is switched so as to perform double voltage rectification in the welding power supply. Then, the low-voltage AC voltage is double-voltage rectified by the switched rectifier and the two smoothing capacitors, and the inverter is supplied with the same voltage as when a high voltage is supplied. Thus, the voltage supplied to the inverter is maintained at the same value regardless of whether the AC voltage is a high voltage or a low voltage. The high-frequency output voltage generated by the inverter is supplied to an output transformer, and the high-frequency voltage induced on the secondary side of the output transformer is rectified and smoothed and supplied to a welding load.

[0003]

However, such a power supply device has a problem that the power factor is poor because a smoothing capacitor is used. Also, in this power supply,
When the supply of power is started, a large inrush current flows because the smoothing capacitor is in a discharged state. In order to prevent this, there is also a problem that it is necessary to provide a current limiting resistor.

[0004]

A power supply device according to the present invention includes first and second series means each including two rectifying elements connected in the same polarity and connected in parallel between two output terminals. A first and a second self-extinguishing type semiconductor switching element respectively connected in anti-parallel to the rectifying element of the first series means, and an interconnection point of the rectifying element of the second series means and the An interconnection point between the first and second semiconductor switching elements has a rectifying means serving as an input terminal connected to an AC power supply via a reactor. At least two smoothing capacitors are connected in series between the two output terminals. Opening / closing means is connected between the interconnection point of the two smoothing capacitors and the input terminal on the second series means side. When the voltage of the AC power supply is equal to or higher than a predetermined threshold, the switching means is opened, and when the voltage of the AC power supply is smaller than the threshold, the opening / closing control means is closed. The voltage and current of the AC power supply are input, so that the phase of the current of the AC power supply matches the phase of the voltage of the AC power supply,
When the voltage of the AC power supply has one polarity, the first self-extinguishing type semiconductor switching element is opened and closed. When the voltage of the AC power supply is the other polarity, the second self-extinguishing type semiconductor switching element is opened and closed. There is provided a control means for performing the operation. The rectifying elements of the first series means are thyristors, respectively.
When the AC power supply has one polarity, the thyristor connected to the second self-extinguishing type semiconductor switching element conducts. When the AC power supply has the other polarity, the thyristor performs the first self-extinguishing. The one connected to the type semiconductor switching element conducts.

[0005]

[0006]

[0007]

[0008]

[0009]

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS As shown in FIG. 1, one terminal 1a of an AC power supply 1 is connected to one input terminal 4 of a rectifier 3 via a reactor 2 (which may be a wiring reactor). I have. The other terminal 1 b of the AC power supply 1 is connected to the other input terminal 5 of the rectifier 3.

The rectifier 3 is of a bridge type having thyristors 6 and 7 and diodes 8 and 9. The thyristor 6 has an anode connected to the input terminal 4 and a cathode connected to one output terminal 10. The thyristor 7 has a cathode connected to the input terminal 4 and an anode connected to the other output terminal 11. These thyristors 6, 7
Constitute a first series circuit connected to the same polarity. The diode 8 has an anode connected to the input terminal 5 and a cathode connected to the output terminal 10. The diode 9 has a cathode connected to the input terminal 5 and an anode connected to the output terminal 11. Diodes 8, 9
Constitutes a second series circuit connected to the same polarity as the thyristors 8 and 9.

A self-extinguishing type semiconductor switching element, for example, a conductive path of an IGBT 12 is connected in antiparallel with the thyristor 6. That is, in the thyristor 6, a current flows from the input terminal 4 to the output terminal 10, whereas this conductive path is
A current flows from the output terminal 10 to the input terminal 4. Similarly, the conductive path of the IGBT 13 is connected in antiparallel with the thyristor 7. In the thyristor 7, a current flows from the output terminal 11 side to the input terminal 4 side, whereas in this conductive path, a current flows from the input terminal 4 side to the output terminal 11 side.

[0013] Smoothing capacitors 14 and 15 are connected in series between output terminals 10 and 11 of the rectifier 3. Opening / closing means, for example, a triac 17 is connected between the interconnection point 16 of the smoothing capacitors 14 and 15 and the input terminal 5 of the rectifier 3.

Thyristors 6, 7, IGBTs 12, 13,
The triac 17 is on / off controlled by the control device 32. In order to control the thyristors 6 and 7 and the IGBTs 12 and 13, the control device 32 includes a terminal 1a of the AC power supply 1,
The input voltage to the rectifier 3 detected by the current transformer 31 provided between the terminal 1b and the input terminal 5 of the rectifier 5 is input while the AC voltage between the terminals 1b and 1b is input. The control device 32 controls the thyristors 6, 7 and the IGBTs 12, 13 so that the input current to the rectifier 3 follows the AC voltage, as described later.

For controlling the triac 17, the control device 32 is provided with opening / closing control means, for example, a voltage switching device 33. This voltage switching device 33 has an auxiliary transformer 51 into which the AC voltage of the AC power supply 1 is input to the primary winding. The auxiliary transformer 51 induces an AC voltage, which is obtained by stepping down the input AC voltage, in the secondary winding. The induced secondary AC voltage is rectified by the auxiliary rectifier 52 and smoothed by the smoothing capacitor 53. A Zener diode 54 is connected in series between both ends of the smoothing capacitor 52.
And the resistor 55 are connected. Smoothing capacitor 52
, A collector-emitter conductive path of the switching transistor 56 and a relay 57 are connected in series. A relay contact 58 that is closed when the relay 57 is energized is connected to the control device 32. Control device 3
2 turns off the triac 17 when the relay contact 58 is closed, and turns on the triac 17 when the relay contact 58 is opened. A connection point between the Zener diode 54 and the resistor 55 is connected to the base of the switching transistor 56. As the Zener diode 54, one that conducts when the AC voltage of the AC power supply 1 is, for example, 200 V, and becomes non-conductive when, for example, 100 V is used.

The input side of the inverter 20 is connected between the smoothing capacitors 14 and 15. This inverter 2
0 is a self-extinguishing type semiconductor switching element, for example, IG
It is a half-bridge type using BT21 and BT22. In the inverter 20, conductive paths of the IGBTs 21 and 22 are connected in series between the smoothing capacitors 14 and 15. An inverter control signal is supplied from an inverter control device 23 to the bases of the IBGTs 21 and 22. The flywheel diodes 23a and 23b are connected to the conductive paths of the IGBTs 21 and 22, respectively.

The interconnection point between the conductive paths of the IGBTs 21 and 22 and the interconnection point 16 between the smoothing capacitors 14 and 15 are:
That is, the output side of the inverter 20 is connected to the primary winding of the output transformer 26 via the DC cut capacitor 25. The output transformer 26 is provided to insulate the high-frequency alternating current of the inverter 21 and reduce the voltage to a predetermined voltage. Both ends of the secondary winding are connected to output rectifiers 27 and 28.
It is connected to the output terminal 30a via the smoothing reactor 29. The other output terminal 30b is connected to an intermediate tap of the secondary winding. For example, a welding load is connected between the output terminals 30a and 30b.

Next, the AC voltage of the AC power supply 1 is
The operation in the case of a high voltage, for example, 200 V as shown by a solid line in FIG. In this case, as described above, the relay contact 58 is closed, and the triac 17 is off.

As shown at t0 in FIG. 2A, when the voltage of the terminal 1a of the AC power supply 1 becomes higher than the voltage of the terminal 1b, the thyristor 6 is controlled by the control device 3 as shown in FIG.
2 is turned on. This state corresponds to terminal 1 of AC power supply 1.
It continues until time t1 when the voltage at a is higher than the voltage at terminal 1b. That is, the thyristor 6 is fully conducting over the period of the positive half cycle of the AC power supply 1. Also, during this positive half cycle, the control device 32 turns on and off the IGBT 13 as shown in FIG.

When the IGBT 13 is on, a current flows from the terminal 1a of the AC power supply 1 to the terminal 1b of the AC power supply 1 via the reactor 2, the IGBT 13, and the diode 9. At this time, energy due to the voltage in the direction indicated by the arrow is stored in the reactor 2.

When the IGBT 13 is turned off, energy is released from the reactor 2 so that the current flowing through the reactor 2 flows in the same direction as before. As a result, the current flows from the reactor 2 to the thyristor 6 and the smoothing capacitor 1
The current flows to the reactor 2 via the terminals 4 and 15, the diode 9, and the terminal 1b of the AC power supply 1, and the smoothing capacitors 14 and 15 are charged. The voltage is about 280 V at maximum (double the 200 V route).

As shown in the period from t1 to t2 in FIG. 2A, during the negative half cycle in which the voltage at the terminal 1b of the AC power supply 1 is higher than the voltage at the terminal 1b, as shown in FIG. The control device 32 conducts the thyristor 7. That is, full conduction is performed. Also, during this half cycle, the control device 32 turns the IGBT 12 on and off.

When the IGBT 12 is on, a current flows from the terminal 1b of the AC power supply 1 to the terminal 1a of the AC power supply 1 via the diode 8, the IGBT 12, and the reactor 2. At this time, energy is stored in the reactor 2 by a voltage in the direction opposite to the arrow.

When IGBT 12 is off, reactor 2
So that the direction of the current flowing through
AC power supply 1, diode 8, smoothing capacitor 14, 1
5, a current flows to the thyristor 7 and the reactor 2, and the smoothing capacitors 14 and 15 are charged, and the voltage thereof becomes a maximum of about 280V.

By controlling the IGBTs 12 and 13 and the thyristors 6 and 7, the AC voltage of the AC power supply 1 is full-wave rectified and smoothed. The control device 32 controls the current of the AC power supply 1 based on the voltage of the AC power supply 1 so that the phase of the current flowing from the AC power supply 1 matches the phase of the voltage of the AC power supply 1.
The on and off periods of the GBTs 12 and 13 are controlled. That is,
The IGBTs 12 and 13 are PWM-controlled to improve the power factor of the AC power supply 1.

For example, as a result of using this power supply in a place different from the place where it has been used, the voltage of the AC power supply 1 becomes 100 V as shown by a dotted line in FIG.
It may be. In this case, the relay contact 58 is opened as described above, and the control device 32
Turn on.

When the voltage at the terminal 1a of the AC power supply 1 becomes higher than the voltage at the terminal 1b as shown at time t0 in FIG. 2A, the control device 32 switches the thyristor 6 as shown in FIG. Is turned on. This state continues for a positive half cycle. Also, during this period, the control device 32
The GBT 13 is turned on and off.

When the IGBT 13 is on, a current flows from the terminal 1a of the AC power supply 1 to the terminal 1b of the AC power supply 1 via the reactor 2, the IGBT 13, and the diode 9, and energy is stored in the reactor 2 by a voltage in the direction of the arrow. Is done. When the control device 32 turns off the IGBT 13,
The reactor 2 releases the stored energy so that the current flowing therethrough flows as it is, and the reactor 2
Then, a current flows through the reactor 2 through the thyristor 6, the smoothing capacitor 14, the triac 17, and the terminal 1b of the AC power supply 1, and the smoothing capacitor 14 is charged. At this time,
The voltage of the smoothing capacitor 14 is a maximum of about 140 V (double the route of 100 V).

At time t1 when the voltage at the input terminal 1b becomes higher than the voltage at the input terminal 1a, the control device 32 turns on the thyristor 7. This state continues for a negative half cycle. During this period, the IGBT 12
2 is turned on and off.

When the IGBT 12 is on, a current flows from the terminal 1b of the AC power supply 1 to the terminal 1a via the diode 8, the IGBT 12, and the reactor 2, and energy is stored in the reactor 2 by a voltage in the direction opposite to the arrow. IG
When the BT 12 is turned off by the control device 32, in order to make the direction of the current flowing through the reactor 2 the same as before, the AC power source 1, the triac 1
A current flows through the reactor 2 via the smoothing capacitor 15 and the thyristor 7. Thereby, the smoothing capacitor 15
Is charged, and its voltage becomes about 140V.

By turning on the triac 17, the rectifier 3 operates as a voltage doubler rectifier circuit. The control device 32 uses the voltage of the AC power supply 1 as a reference,
The ON / OFF periods of the IGBTs 12 and 13 are controlled so that the phase of the current flowing from the AC power supply 1 matches the phase of the voltage of the AC power supply 1. That is, the IGBTs 12 and 13 are PWM
It controls and improves the power factor of the AC power supply 1.

The voltage charged in the smoothing capacitors 14 and 15 is supplied to an IGBT controlled by an inverter control device to turn on and off.
High-frequency switching is performed by 21 and 22 to obtain a high-frequency AC voltage. This high-frequency AC voltage is supplied to the output transformer 2
The voltage is lowered by rectification 6 and rectified and smoothed. This rectified smoothed output is supplied to a welding load connected to the output terminals 30a and 30b.

By the way, when this power supply is started,
The smoothing capacitors 14 and 15 are discharged. Therefore,
As described above, when the thyristors 6 and 7 are brought into full conduction from the start-up, excessive currents flow through the capacitors 14 and 15, respectively. In order to prevent the occurrence of the excessive current, for example, in the case of the thyristor 6, the firing angle is gradually reduced from 180 degrees every positive half cycle from the start,
The current flowing through the smoothing capacitors 14 and 15 is gradually increased. Similarly, the thyristor 7 is controlled at every negative half cycle at the time of startup. That is, the thyristors 6 and 7 are under soft start control at the time of startup.

In the above embodiment, the triac 17 is used as the opening / closing means. Alternatively, for example, two thyristors connected in anti-parallel can be used. Further, instead of the triac 17, a relay contact driven by the relay 57 can be used.

In the above embodiment, thyristors 6 and 7 are used for rectifier 3. This is for performing a soft start at the time of startup and preventing the occurrence of an excessive current at the time of startup. However, if appropriate current limiting means is provided, thyristors 6 and 7 may be replaced by ordinary rectifier diodes.

Although the diodes 8 and 9 are used in the above embodiment, a thyristor may be used instead. In this case, the thyristor replacing the diode 8 is turned on by the control device 32 when the thyristor 7 is on. Similarly, when the thyristor 6 is turned on, the control device 3
2 is turned on.

[0037]

As described above, according to the present invention, it is possible to supply power to a predetermined load regardless of whether the voltage of the AC power supply input to the power supply is high or low. In addition, since the first and second self-extinguishing semiconductor switching elements are controlled such that the current flowing from the AC power supply follows the voltage of the AC power supply, the power factor can be improved.

Further, according to the present invention, a thyristor is used as at least one of the rectifying elements of the first or second series means. Therefore, since the soft start can be performed at the time of starting, the inrush current flowing to the smoothing capacitor at the time of starting can be reduced.

[Brief description of the drawings]

FIG. 1 is a block diagram showing one embodiment of a power supply device according to the present invention.

FIG. 2 is an operation waveform diagram of the embodiment.

[Explanation of symbols]

Reference Signs List 1 AC power supply 2 Reactor 3 Rectifier circuit 6 7 Thyristor (first series means) 8 9 Diode (second series means) 12 13 IGBT (first and second self-extinguishing semiconductor switching elements) 14 15 Smoothing capacitor 17 Triac (switching means) 32 Controller (control means) 33 Voltage switching device (switching control means)

Continuation of the front page (56) References JP-A-4-13863 (JP, A) JP-A-3-855 (JP, Y2) (58) Fields investigated (Int. Cl. ⁷ , DB name) H02M 7 / 00-7/40

Claims (1)

(57) [Claims] A first rectifying element connected in parallel between two output terminals, the first rectifying element including two rectifying elements connected to the same polarity;
And a second series means, and first and second self-extinguishing semiconductor switching elements connected in inverse parallel, respectively to the rectifier elements of the first series unit, the rectifier of the second series means A rectifying means in which an interconnection point of the elements and an interconnection point of the first and second semiconductor switching elements are input terminals connected to an AC power supply via a reactor; and between the two output terminals, At least two smoothing capacitors connected in series; switching means connected between an interconnection point of the two smoothing capacitors, and the input terminal on the second series means side; and a voltage of the AC power supply Is greater than or equal to a predetermined threshold, the switching means is opened, and when the voltage of the AC power supply is smaller than the threshold value, the opening and closing control means for closing the switching means, and the voltage and current of the AC power supply are input. Is on AC power supply
Make sure that the phase of the current matches the phase of the voltage of the AC power supply.
When the voltage of the AC power supply has one polarity, the first self-extinguishing type semiconductor switching element is opened and closed. When the voltage of the AC power supply has the other polarity, the second self-extinguishing type semiconductor switching element. and control means for opening and closing the, provided, rectifying element thyristor der each of the first series means
These thyristors are designed so that the AC power supply has one polarity.
When connected to the second self-extinguishing type semiconductor switching element
Is turned on, and the AC power supply has the other polarity.
When connected to the first self-extinguishing type semiconductor switching element
Power supply device that conducts electricity .