JPS6126309B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a thyristor voltage controlled power supply device suitable for use in a power supply system capable of power regeneration.

As shown in Fig. 1, a conventional power supply system capable of power regeneration is a thyristor voltage control system for forward conversion and supply of power from a power supply between a common AC power line 1 and a common regenerative load 2. It is constructed by connecting in parallel a power supply device 3 and a thyristor voltage controlled power regeneration device 4 for performing reverse conversion and regenerating power. To explain this circuit in more detail, in the thyristor voltage controlled power supply device 3, an isolation transformer 5 is connected to the 3-phase AC power supply line 1.
A thyristor-controlled rectifier circuit 6, ie, a voltage-controllable forward conversion circuit, is connected via the thyristor-controlled rectifier circuit 6. This controlled rectifier circuit 6 is a well-known three-phase full-wave controlled rectifier circuit in which six thyristors S ₁ to S ₆ are bridge-connected, and is controlled by controlling the conduction phase, that is, the control angle, of the thyristors S ₁ to S ₆ . This provides a constant voltage output. At the output stage of the controlled rectifier circuit 6, a smoothing reactor 7 is connected in series to the line, a voltage source capacitor 8 is connected in parallel to the line, and a pair of output lines 9, 10 from which a smoothed voltage is obtained is connected. A load 2 including, for example, a motor, which can regenerate electric power, is connected to positive and negative output terminals 11 and 12 of the power generator. Further, a first comparator circuit 13 consisting of an error amplifier for constant voltage control of the output voltage V ₁ between the pair of output terminals 11 and 12 is provided, and one input terminal of the first comparator circuit 13 is connected between the pair of output lines 9 and 10. A reference voltage circuit 14 consisting of a potentiometer that sets and applies a reference voltage V ₀ is connected to one input terminal of the reference voltage circuit 14 . In this example, the output voltage V ₁ is detected without using a voltage dividing resistor, but when detecting the output voltage V ₁ using a voltage dividing resistor, the detection voltage (divided voltage value) of V ₁ The control is such that the and reference voltage V ₀ become equal, and a target voltage V ₁ corresponding to V ₀ is obtained on the output line. Reference numeral 15 denotes a gate signal generation circuit for forward conversion, which converts thyristors S 1 _{to 1} based on the voltage for synchronization obtained from the AC power supply line 1 and the error amplification output of the comparator circuit 13.
This is a well-known phase control circuit that forms the gate signal for forward conversion of _S6 .

On the other hand, in the thyristor voltage controlled power regeneration device 4 shown on the lower side of FIG. 1, a pair of input lines 16 and 17 are connected to the power regeneration load 2, and a smooth A current source reactor 19 is connected in series to the input line 16. 20 is a thyristor voltage control inverse conversion circuit, and input lines 21 and 22 are connected to the AC power supply side of the reactor 19.
Six thyristors S ₇ bridge-connected between
This is a three-phase full-wave rectifier circuit consisting of _S12 . Such an inverse conversion circuit is well known, for example, from pages 62 to 63 of "Thyristor Utilization Freely" published by Seibundo Shinkosha Co., Ltd. on July 15, 1961. The AC output line of the inverse conversion circuit 20 is coupled to the three-phase AC power line 1 via an isolation transformer 23.

In order to control this inverse conversion circuit 20 so that the input voltage V ₁ becomes equal to the reference voltage V ₀ , a second comparison circuit 24 consisting of an error amplifier is provided.
The output voltage V ₁ of the load 2 is applied to one input terminal, and the reference voltage V ₀ is applied to the other input terminal. Note that in this example, a voltage dividing resistor is not provided to detect the output voltage V ₁ , but if a voltage dividing resistor is provided, of course it will be necessary to ensure that the detection voltage of V ₁ and the reference voltage V ₀ are equal. The target voltage corresponding to _V0 is obtained as _V1 . 25 is a gate signal generation circuit for inverse conversion, and comparison circuit 2
Based on the error output obtained from 4 and the AC power supply voltage obtained from the power supply line 1 in order to synchronize with the AC power supply, the thyristors S7 to _S7 of the inverse conversion circuit 20
This generates a gate signal that controls _S12 . More specifically, the regenerative power is controlled so that the input voltage V ₁ becomes the same as the reference voltage V ₀ .
This is a well-known circuit that controls the conduction phase of the thyristors S ₇ to _{S 12} of the inverse conversion circuit 20.

By the way, in the power supply system capable of power regeneration as described above, when the output voltage V ₁ becomes higher than the reference voltage V ₀ , the forward conversion circuit, that is, the thyristor-controlled rectifier circuit 6 operates to lower its output voltage. If there is regenerative power, thyristors S ₁ to _{S 6}
Even if the conduction period of V1 becomes zero, the output voltage _V1 will be obtained. Therefore, during power regeneration operation,
The thyristors S ₁ to _{S 6} are kept substantially non-conducting, and no power is supplied to the load 2 from the control rectifier circuit 6. Conversely, the regenerative power obtained from the load 2 is supplied to the inverter circuit 20. It is controlled and returned to AC power. Therefore, efficient power supply becomes possible. However, in the method shown in FIG. 1, when the power regeneration state ends, the load 2 is passed through the control rectifier circuit 6 again.
When power _is supplied _to
The conduction angle of S ₁ to S ₆ had to be changed significantly. Then, a delay in the response of the phase control of the thyristors S ₁ to _{S 6} occurred, resulting in a problem that the output voltage V ₁ temporarily decreased significantly compared to the reference voltage V ₀ . We have just described a regenerative power supply system, but when selectively powering a common load from multiple thyristor-controlled rectified power sources, or selectively supplying power to a load using a single thyristor voltage-controlled power supply device using a switch. A similar problem arises when connecting.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a thyristor voltage controlled power supply device that can prevent a drop in output voltage at the start of power supply.

To achieve the above object, the present invention includes a thyristor-controlled rectifier circuit connected between an AC power supply and a load, a smoothing circuit connected to an output line of the thyristor-controlled rectifier circuit, and a smoothing circuit and the load. a power supply selection switch (for example, diode 26 in the embodiment) connected between the thyristor-controlled rectifier circuit and configured to be turned on when power is supplied to the load via the thyristor-controlled rectifier circuit; A dummy DC power supply connected in parallel to the output line with the switch via an impedance for flowing a dummy current, and an output voltage of the output line between the smoothing circuit and the switch are determined. a reference voltage circuit that supplies a reference voltage for voltage control; a comparison circuit that compares the reference voltage applied from the reference voltage circuit with the output voltage or a detection voltage corresponding thereto; and an output of the comparison circuit. a gate signal generation circuit that forms a gate signal for constant voltage control of the thyristor-controlled rectifier circuit so that the output voltage becomes a value corresponding to the reference voltage based on the thyristor-controlled rectifier circuit, and supplies the gate signal to the thyristor of the thyristor-controlled rectifier circuit. The dummy DC power supply has a direction opposite to the direction of the output voltage of the thyristor-controlled rectifier circuit obtained through the smoothing circuit, and the dummy DC power supply regulates the thyristor-controlled rectifier circuit based on the reference voltage. The present invention relates to a thyristor voltage controlled power supply device characterized in that it is configured to generate a voltage having a lower value than the output voltage obtained by voltage control.

In the power supply device of the above invention, when the switch is turned off (non-conducting state) and the thyristor-controlled rectifier circuit is electrically disconnected from the load, the smoothing circuit is activated by the function of the dummy DC power supply having the opposite polarity. The output voltage is pulled down and the thyristor controlled rectifier circuit operates to raise this pulled down voltage. Therefore, the conduction width of the thyristor of the thyristor-controlled rectifier circuit does not decrease significantly during the off-period of the switch. As a result, even when the switch is turned on again and a load is connected to the thyristor-controlled rectifier circuit, it is not necessary to significantly change the conduction angle of the thyristor, and a voltage drop at the start of power supply can be prevented.

Embodiments of the present invention will be described below with reference to the drawings. However, since the parts indicated by reference numerals 1 to 25 in FIG. 2 are substantially the same as those shown by the same reference numerals in FIG. 1, their explanation will be omitted.

In the thyristor voltage controlled power supply device 3 shown in FIG. 2, which shows a power supply system capable of power regeneration, the smoothing reactor 7 has a directionality that allows current to flow from the power source toward the load 2. A first rectifier diode 26 that functions as a power supply selection switch is connected in series to the output line 9 after the output line 9, and a first impedance 27 and a first dummy are connected between the output lines 9 and 10 on the power supply side of the diode 26. A first series circuit with a DC power supply 28 is connected.
The direction of the voltage _V3 of the dummy DC power supply 28 is set to be opposite to the direction of the output voltage of the thyristor control rectifier circuit 6, and the value of the voltage _V3 is a value lower than the target voltage, that is, the reference voltage _V0 . The conduction angle is set so that a conduction angle approximately equal to the conduction angle of the thyristors S ₁ to _{S 6} when power is supplied to the load 2 from the thyristor-controlled rectifier circuit 6 is obtained when the diode 26 is off, that is, during regeneration. ing. Further, one input terminal of the comparison circuit 13 is connected between the first rectifier diode 26 and the reactor 7. In this embodiment, the output voltage V ₂ is detected without using a voltage dividing resistor, so the control is performed so that the target output voltage V ₁ and the reference voltage V ₀ match.
If a voltage dividing resistor is provided, control is naturally performed such that the detected voltage of V ₁ and the reference voltage V ₀ match, and an output voltage V ₁ corresponding to V ₀ can be obtained.

On the other hand, in the thyristor voltage controlled power regeneration device 4, the load 2 capable of power regeneration is connected to the inverse conversion circuit 2.
A second rectifier diode 29 is connected in series with the input line 16 leading to zero, which serves as a power regeneration selection switch. Further, a second series circuit including a second impedance 30 and a second dummy DC power source 31 is connected between the pair of input lines 16 and 17 on the power source side of the diode 29. The direction of the voltage V ₅ of the second dummy DC power supply 31 is as follows:
The direction is the same as that of the regenerative voltage V ₁ supplied from the load 2, and the value of this voltage V ₅ is set higher than the regulated input voltage V ₄ obtained corresponding to the reference voltage V ₀ . The conduction angle is set so that a conduction angle substantially equal to the conduction angle of the thyristors S ₇ to _{S 12} of the inverse conversion circuit 20 when power regeneration is performed is obtained when the diode 29 is off, that is, when no regeneration is performed. Further, one input terminal of the comparator circuit 24 is connected to the input line 16 between the second rectifier diode 29 and the reactor 19. In this example, the input voltage V ₄ is detected without using a voltage dividing resistor, so the input voltage V ₄ directly serves as the detection voltage and is compared with the reference voltage V ₀ . In this case, the detected voltage of the input voltage V ₄ and the reference voltage V ₀ are naturally compared, and control is performed to match the two, so that the input voltage V ₄ corresponding to V ₀ is obtained.

Next, the operation of this circuit will be explained. Now, if power is being supplied to the load 2 through the thyristor-controlled rectifier circuit 6, the voltage _V2 at the front stage of the first rectifier diode 26 is detected and becomes the input to the first comparator circuit 13, which is the reference voltage. It is compared with the voltage V ₀ . Then, the thyristor-controlled rectifier circuit 6 is controlled so that V ₂ =V ₀ and V ₁ ≈V ₀ . During such forward conversion, the thyristor voltage controlled power regeneration device 4
In this case, since the voltage V ₄ on the power supply side of the second rectifier diode 29 is controlled to be approximately equal to the reference voltage V ₀ , V ₄ >V ₁ and the second rectifier diode 29 is kept off. Therefore, the second comparator circuit 24 receives the voltage V ₄ on the power supply side of the second rectifier diode 29 as a selection switch.
is applied, and this voltage V ₄ and the reference voltage V ₀ are compared. By the way, the second dummy DC power supply 31
Since the voltage V ₅ is set higher than the reference voltage V ₀ , the dummy current I _D2 is injected through the impedance 30 . Therefore, the inverse conversion circuit 20 operates to lower the voltage V ₄ between the input lines 16 and 17, which has been increased by the voltage V ₅ of the dummy DC power supply 31, to the reference voltage V ₀ , and the thyristors S ₇ to S ₁₂ are The conduction angle is controlled to a large target. That is, if the current source reactor 19 is set to allow the dummy injection current I _D2 to flow continuously, the conduction angles, that is, the firing phases of the thyristors S ₇ to _{S 12} of the inverse conversion circuit 20 are substantially the same as during power regeneration. can be made identical.

When the load 2 changes from the power supply state due to the above-mentioned forward conversion to a state where it generates regenerative power, the terminals 11 and 1
The voltage V ₁ between the two becomes higher than the reference voltage V ₀ . Therefore, V ₂ <V ₁ and the first rectifier diode 26 as the first selection switch is turned off.
Instead, the second rectifier diode 29 as the second selection switch is turned on. and inverse conversion circuit 2
If a voltage of V ₄ >V ₀ is input to V 0 , the thyristors S ₇ to S ₁₂ are controlled so that V ₄ =V ₀ , and regenerated power is sent to the power supply line 1. At the time of this switching, in the device of this embodiment, by the action of the second dummy DC power supply 31, the thyristors _S7 to _S12 of the inverse conversion circuit 20 are set to approximately the same conduction angle as during power regeneration control before the regeneration operation. Since it is controlled, there is no need to significantly change the conduction angle of the thyristors _S7 to _S12 . Therefore,
At the start of regeneration, the voltage V ₄ is suppressed from temporarily rising above the reference voltage V ₀ , and the input side is prevented from becoming overvoltage.

During this power regeneration period, the first rectifier diode 26 is off, so no power is supplied to the load 2 by the thyristor-controlled rectifier circuit 6.
However, the voltage V ₃ at the first dummy DC power supply 28
is given, and the potential of line 9 becomes impedance 2
7, the thyristor-controlled rectifier circuit 6 is controlled to cancel this voltage reduction. That is, even during regeneration, the voltage V ₂ and the reference voltage V ₀ are compared in the first comparison circuit 13 and controlled so that V ₂ =V ₀ . If there is no dummy DC power supply 28, the conduction period of the thyristors _S1 to _S6 will be _zero as explained in FIG. If the voltage is reduced, the thyristors S ₁ to _{S 6} conduct to compensate for this, and the period of conduction becomes relatively large. If the smoothing reactor 7 is set to allow the dummy current I _D1 to flow continuously, the conduction angle of the forward conversion thyristors S ₁ to _{S 6} is such that the power is supplied to the load 2 via the thyristors S ₁ to _{S 6} . It will be almost the same as when it is being supplied. Therefore, the power regeneration state is switched to the forward conversion state, and the first rectifier diode 2
6 is turned on and the second rectifier diode 29 is turned off, the transient drop in the output voltage V ₁ becomes extremely small. That is, even if power supply by the forward conversion thyristors S ₁ to _{S 6} is started, the thyristors S ₁ to _{S 6}
It is not necessary to significantly change the conduction angle of
A voltage of V ₂ =V ₀ can be obtained immediately.

As is clear from the above, according to this example,
A stable power supply can be continued by limiting the transient voltage drop when switching from the power regeneration state to the forward conversion state. Furthermore, stable power regeneration can be performed by limiting the transient voltage rise when switching from the forward conversion state to the power regeneration state.

Although the embodiments of the present invention have been described above, the present invention is not limited thereto and can be further modified. For example, the thyristor-controlled rectifier circuit 6 and the inverse conversion circuit 20 may of course be single-phase or multi-phase other than three-phase. Further, the thyristor-controlled rectifier circuit 6 may not be a bridge circuit including only the thyristors _S1 to _S12 , but may be a variety of known conversion circuits that combine thyristors and diodes, for example. Further, instead of the diodes 26 and 29, another switch such as another semiconductor switch capable of high-speed switching may be used. In addition, the first and second comparison circuits 13 and 2
The four reference voltages V ₀ may not be common, but may be set independently, and the reference voltages may be determined so that, for example, V ₄ <V ₂ , that is, V ₄ is slightly higher than V ₂ . If the output voltage V ₄ and the input voltage V ₂ are set to different target voltages in this way, the diodes 26 and 2
In combination with 9, it is possible to completely prevent a transient power supply short-circuit phenomenon when switching between forward conversion and power regeneration. It is also applicable to a power supply system in which a separate power source is connected to the load 2. Also, when connecting another power supply device to the load 2 instead of the regeneration device 4, and limiting voltage fluctuations at the time of switching in a method of selectively supplying power to a common load 2 by multiple power supply devices, is also applicable. It is also applicable to cases where power is selectively supplied by a single thyristor voltage controlled power supply device.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram showing a conventional power supply system capable of power regeneration, and FIG. 2 is a circuit diagram showing a power supply system capable of power regeneration according to an embodiment of the present invention. In the symbols used in the drawings, 1 is a power supply line, 2 is a regenerative load, 3 is a thyristor voltage controlled power supply device, 4 is a thyristor voltage controlled power regeneration device, 6 is a thyristor controlled rectifier circuit, and 7 is a thyristor controlled rectifier circuit. A smoothing reactor, 8 a capacitor, 9 and 10 output lines, 13 a first comparison circuit, 14 a reference voltage circuit, 15 a forward conversion gate signal generation circuit,
16 and 17 are input lines, 18 is a smoothing capacitor, 19 is a current source reactor, 20 is a thyristor voltage control inverse conversion circuit, 24 is a second comparison circuit, 2
5 is an inverse conversion gate signal generation circuit, 25 is a first rectifier diode, 27 is a first impedance,
28 is a first dummy DC power supply, 29 is a second rectifier diode, 30 is a second impedance, 3
1 is a second dummy DC power supply.

Claims (1)

[Claims] 1. A thyristor-controlled rectifier circuit connected between an AC power supply and a load, a smoothing circuit connected to an output line of the thyristor-controlled rectifier circuit, and between the smoothing circuit and the load. a power supply selection switch connected and configured to be turned on when power is supplied to the load via the thyristor-controlled rectifier circuit; and a power supply selection switch connected in parallel to an output line between the smoothing circuit and the switch. , a dummy DC power supply connected via an impedance for passing a dummy current, and a reference voltage for supplying a reference voltage for constant voltage control of the output voltage of the output line between the smoothing circuit and the switch. a comparison circuit that compares the reference voltage applied from the reference voltage circuit and the output voltage or a detection voltage corresponding thereto; and a comparison circuit that compares the output voltage with the reference voltage based on the output of the comparison circuit. a gate signal generating circuit for forming a gate signal for controlling the constant voltage of the thyristor-controlled rectifier circuit to a constant voltage value and supplying the gate signal to the thyristor of the thyristor-controlled rectifier circuit, the dummy DC power supply comprising: , an output voltage having a direction opposite to the direction of the output voltage of the thyristor-controlled rectifier circuit obtained through the smoothing circuit, and obtained by constant voltage control of the thyristor-controlled rectifier circuit based on the reference voltage. Thyristor voltage controlled power supply device, characterized in that it is configured to generate a voltage having a value lower than .