JPH053682A - Current type inverter unit - Google Patents

Abstract

(57) [Abstract] [Purpose] It is possible to variably set the rising and falling characteristics of the load current of a current source inverter device that supplies an output to a load having a reactance component, by effectively using the power supply power. To do. A feedback capacitor 8 in which the charge polarity is inverted every time the load current polarity is inverted based on the switching of the inverter 5, and the output capacitor of the inverter 5 charges a part of the output current.
A diode rectifier 9 that rectifies the current flowing through the capacitor 8, a regenerative capacitor 10 that is charged by the output of the rectifier 9 to set the charging time of the capacitor 8, and the capacitor 10 that is provided on the output side.
And a control rectifier 11 for regeneration that regenerates the charging energy of the charging energy into the AC power supply on the input side, and adjusts the slope of the load current at the time of polarity reversal by variably setting the regeneration amount of the charging energy.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a current source inverter device for supplying a constant current controlled alternating current to a load having a reactance component.

[0002]

2. Description of the Related Art Conventionally, when color is generated on an object to be processed by surface modification such as alumite treatment of aluminum, a sine wave current or a rectangular wave current from an AC power supply is applied to the object to be processed. .. When the object having a reactance component is subjected to the constant current control surface modification, the sine wave current and the rectangular wave current are subjected to constant current control and supplied to the object.

By the way, there is a current source inverter device as a power supply device suitable for the constant current AC power supply. And
A conventional current source inverter device includes a control rectifier such as a thyristor rectifier, a DC reactor for constant current control, and an inverter, and controls the conduction angle of the thyristor of the control rectifier so that the rectified output is a constant current. The power supply is rectified, the rectified output is supplied to the inverter via the DC reactor, and the alternating current subjected to constant current control is output by the switching of the inverter.

[0004]

In the conventional current source inverter device, the rising and falling slopes of the output current due to the switching of the inverter are determined based on the circuit constants and the like and do not change. Therefore, in the case of a power supply device for surface modification in which the characteristics (time) of rising and falling cannot be changed, the slope of the rising and falling of the load current does not change, and the characteristics of surface modification cannot be adjusted. There is.

It is an object of the present invention to provide a current source inverter device in which the characteristics of surface modification of an object having a reactance component can be freely adjusted and the power source is highly utilized.

[0006]

In order to achieve the above-mentioned object, in the current source inverter device of the present invention, the charge polarity is inverted every time the polarity of the load current is inverted based on the switching of the inverter, and the output of the inverter is output. A feedback capacitor that is charged by a part of the current, a diode rectifier that rectifies the current flowing through this capacitor, a regeneration capacitor that is charged by the output of this rectifier and sets the charging time of the feedback capacitor, and this capacitor A control rectifier for regeneration that is provided on the output side and regenerates the charging energy of the capacitor to the input side AC power supply;

The slope of the load current at the time of polarity reversal is adjusted by variably setting the regeneration amount of the charging energy.

[0008]

In the current source inverter device of the present invention configured as described above, the polarity of the feedback capacitor is reversed by a part of the output current of the inverter every time the polarity of the load current is reversed by the switching of the inverter. After being charged, the negative current converges to a steady value after this charging.

At this time, the current flowing through the feedback capacitor is rectified by the diode rectifier and supplied to the regenerative capacitor, and the capacity (time constant) of the feedback capacitor is determined by the charging voltage of this capacitor.

The charging voltage of the regenerative capacitor is variably set by controlling the conduction angle of the thyristor of the regenerative control rectifier, so that the capacity of the feedback capacitor changes equivalently until the load current converges to a steady value. Time changes,
The rising and falling slopes of the load current are variably set. Moreover, the surplus of the charging energy of the regenerative capacitor is regenerated to the AC power source via the regenerative control rectifier, and the power source power is effectively used without waste.

[0011]

EXAMPLE One example will be described with reference to FIGS. As shown in FIG. 1, commercial three-phase AC power is supplied from the input terminals 1a, 1b, 1c to the input winding 2a on the primary side of the input transformer 2 having a three-winding configuration, and the secondary winding of the transformer 2 is supplied. The output of the side output winding 2b is supplied to the input control rectifier 3 having the bridge circuit configuration of the thyristors 3a to 3f.

This control rectifier 3 comprises thyristors 3a to 3f.
The output of the output winding 2b is rectified by controlling the conduction angle of (1) to form a constant current rectified output. Further, the rectified output of the control rectifier 3 is smoothed by the DC reactor 4 for constant current control, and a current id converted into a substantially predetermined value Id shown by the solid line in FIG. 2A is formed and supplied to the inverter 5. To be done.

The inverter 5 is composed of a bridge circuit of thyristors 5a to 5d as self-arc extinguishing type control elements, and the thyristors 5a and 5d and the thyristors 5b and 5c are switched in opposite phases to convert direct current to alternating current. Is supplied to the load 7 via the output transformer 6. The load 7 has a resistance component Ro and a reactance component Lo.

If the output current of the inverter 5 is made to be a complete rectangular wave current, the thyristors 5a to 5d are destroyed due to the simultaneous ON state and the like, so that the rising and falling of the output current are trapezoidal waves. The inverter 5 is switching-controlled in the cycle T so as to obtain the characteristics.

Further, when the thyristors 5b and 5c change from off to on, the commutation from negative to positive is defined, and when the thyristors 5a and 5d change from off to on, the commutation from positive to negative is defined. Due to the commutation from negative to positive, the thyristor 5b passes from the thyristor 5b through the primary side of the output transformer 6.
A current flows through the load 7, and at this time, the output voltage eo and the output current (load current) io having the polarities shown in FIG. 1 are supplied to the load 7. In addition, the commutation from positive to negative causes the output transformer 6 from the thyristor 5a.
Current flows through the thyristor 5d through the primary side of the output voltage eo and the output current io supplied to the load 7 at this time.

Then, as shown in FIG. 2B, the output current io alternates between positive and negative steady values + Io and -Io with trapezoidal wave characteristics.

Next, the detailed operation during commutation will be described.
For example, when a commutation from negative to positive occurs at time tn when the output current io = -Io and the thyristors 5a and 5d are turned off, the output current io changes from -Io mainly due to the energy release of the reactance component Lo of the load 7. It decreases and reaches ₀ at time t ₀ .

The current id is held at a constant current by the DC reactor 4, and an electromotive force proportional to the reactance component Lo is generated on the primary side of the output transformer 6. Then, the current of this electromotive force is supplied to the feedback capacitor 8 as the current irg in FIG.

This capacitor 8 is composed of thyristors 5a and 5d.
During the ON period, the battery is charged and held in the polarity shown in FIG. 1, and is reversely charged and discharged by the supply of the current irg. Furthermore, thyristor 5
When b and 5c are turned on, a part of the output current of the inverter 5 corresponding to id-io is supplied to the feedback capacitor 8 as the current irg, and the capacitor 8 is charged to the reverse polarity shown in the figure. It

Further, based on the output of the inverter 5, an output voltage eo and an output current io having the illustrated polarities are generated in the output transformer 6,
This current io flows through the load 7. At this time, the output current io rises to a steady value + Io with a slope according to the time constants of the feedback capacitor 8 and the load 7, and converges.

Further, the current irg decreases as the feedback capacitor 8 is charged, as shown in FIG.
The capacitor 8 is fully charged and the output current io is + Io
When it converges to, it will not flow thereafter. At the next positive-to-negative commutation, the output current io changes from the steady value + Io to 0.
1, the current irg having a polarity opposite to that in FIG. 1 flows, the capacitor 8 is charged to the polarity shown, and the output current io falls to the steady value −Io.

Since the rising and falling slopes of the output current io during commutation depend on the capacity (charging time constant) of the feedback capacitor 8, if the capacity of this capacitor 8 is varied to change the charging time, The slope characteristics change as the rise and fall times of the output current io change.

Therefore, a diode rectifier 9 having a bridge circuit configuration of the diodes 9a to 9d and a regeneration capacitor 10 are provided.
Equipped with.

In addition, the secondary side of the input transformer 2 is provided with a 3 for regeneration.
A secondary winding 2c is provided, and the thyristor 11a-
An input side of a regenerative control rectifier 11 having a bridge circuit configuration of 11f is connected, and a DC reactor 12 and a regenerative capacitor 10 are connected in series to an output side of the control rectifier 11. Then, the diode rectifier 9 full-wave rectifies the current irg, and the current flowing through the feedback capacitor 8 constantly charges the regeneration capacitor 10 to the polarity shown in FIG.

At this time, the thyristor 1 of the control rectifier 11
The charging rating of the regenerative capacitor 10 changes due to the variable conduction angle of 1a to 11f, and the capacitor 10 is equivalently
The capacity of changes. Then, the charging time of the feedback capacitor 8 due to the current irg changes depending on the charging voltage of the regeneration capacitor 10, and the capacity of the feedback capacitor 8 changes equivalently to change the rising and falling times of the output current io. , Its slope characteristics change.

Therefore, by variably setting the conduction angles of the thyristors 11a to 11f, the inclination characteristics of the rising and falling of the output current io can be adjusted freely. Moreover, the surplus of the charging energy supplied to the regeneration capacitor 10 is regenerated to the three-phase AC power source through the control rectifier 11 and the input transformer 2, and the power is effectively used without waste.

By the way, when the voltages of the feedback capacitor 8 and the regeneration capacitor 10 are ec ₁ and ec ₂ , they change as shown by the solid lines in (d) and (e) of FIG. 2, respectively, and ± Ec in the figure.
rg is the convergence value of voltage ec ₁ , and Ecmax, Ec, Ecmin are the voltage ec.
Maximum value of _2, an average value, a minimum value. Also, the output voltage eo
Changes as shown in FIG. 2 (f), at which time the voltage on the primary side of the output transformer 6 is proportional to the output voltage eo on the secondary side.

When the winding ratio n between the primary side and the secondary side of the output transformer 6 is 1, the following formula 1 is established at the commutation start time tn.

[0029]

[Equation 1]

Note that T ₁ represents the period of t ₀ -tn, and R and L represent the values of the resistance component Ro and the reactance component Lo.

At the commutation end time tp, the following equation 2 is established.

[0032]

[Equation 2]

Note that T ₂ indicates a period of tp-t ₀ . And
Since the change rate (dio / dt) of the output current io in the commutation period tn to tp is kept constant and the output current io is linearly changed, T ₁ = T ₂ = T is set. Furthermore, the charging voltage ec of the regeneration capacitor 10
_When the ripple is neglected, Ecmin≈Ecmax≈Ec becomes 2 as is clear from FIG. 2 (e). Therefore, the following equations 3 and 4 hold.

[0034]

[Equation 3]

[0035]

[Equation 4]

Then, the expression of the equation 3 is the regeneration condenser 10
Shows that the voltage of the inductance component Lo of the load 7 is proportional to the voltage Ec of Eq. 4, and the equation (4) shows that the voltage of the resistance component Ro of the load 7 (voltage drop) is proportional to the voltage of the feedback capacitor 8.

Further, the following formula 5 is obtained from the formula 3 and, as is clear from this formula, the voltage Ec of the regeneration capacitor 10 is set as the control target voltage, and this voltage becomes the target voltage. The thyristors 11a to 11 of the control rectifier 11
By controlling the conduction angle of f, the commutation period of the output current io becomes a period corresponding to the target voltage.

[0038]

[Equation 5]

Note that the capacitance C ₁ of the feedback capacitor 8 is obtained from the amount of charged electric charge, and is proportional to the period T as shown in the following equation (6).

[0040]

[Equation 6]

Then, the target voltage is variably set to adjust the charging voltage of the regenerative capacitor 10 so that the commutation period of the output current io based on the switching of the inverter 5 is changed and the rising and falling slopes thereof are changed. The characteristics can be freely adjusted, and when the load 7 is used in a power supply device for surface modification in which an object to be processed is used, it is possible to freely adjust the modification characteristics that cannot be conventionally performed. By the way, although the output transformer 6 is provided in the above embodiment, the transformer 6 may be omitted.

Further, the inverter 5 is composed of thyristors 5a-5
Instead of d, GTO or IGBT may be used. Further, the input AC power supply may be a single-phase power supply or a multi-phase power supply such as 6-phase other than 3-phase.

[0043]

Since the present invention is configured as described above, it has the following effects. Every time the polarity of the load current is inverted due to the switching of the inverter 5, a part of the output current of the inverter 5 causes a feedback capacitor 8
Is charged with the polarity reversed, and the regeneration capacitor 10 is charged with the same polarity by the current obtained by rectifying the current passed through the capacitor by the diode rectifier 9.

Then, the capacitance of the feedback capacitor 8 is equivalently changed by varying the charging voltage of the regenerative capacitor 10, and the time until the voltage of the capacitor 8 converges to a predetermined value is changed and is supplied to the load 7. The slope of the output current, that is, the rise and fall of the load current can be adjusted freely.

Further, the charging energy of the regenerative capacitor 10 is controlled by the regenerative control rectifier 11 for setting the charging voltage.
Is regenerated to the AC power supply on the input side via the, and the power supply power is effectively used without waste.

Therefore, the rising and falling characteristics of the load current can be arbitrarily set by effectively using the power supply, and the current is extremely excellent as a power supply device for surface modification using the load as an object to be processed. Type inverter can be provided.

[Brief description of drawings]

FIG. 1 is a connection diagram of an embodiment of a current source inverter device of the present invention.

2A to 2E are waveform diagrams for explaining the operation of FIG.

[Explanation of symbols]

 3 Input control rectifier 4,12 DC reactor 5 Inverter 7 Load 8 Feedback capacitor 9 Diode rectifier 10 Regeneration capacitor 11 Regeneration control rectifier Lo Reactance component

Claims (1)

Claim: What is claimed is: 1. A rectified output of a constant current of a control rectifier for power supply for rectifying an AC power supply is supplied to an inverter via a DC reactor for constant current control, and AC is switched by switching of the inverter. In a current source inverter device that is formed and supplied to a load having a reactance component, a feedback capacitor in which the charging polarity is inverted every time the polarity of the load current is inverted based on the switching of the inverter and the output current of the inverter is charged. A diode rectifier that rectifies the current flowing through the feedback capacitor; a regeneration capacitor that is charged by the output of the diode rectifier to set the charging time of the feedback capacitor; and the regeneration capacitor that is provided on the output side. Regenerative control adjustment that regenerates the charging energy of the capacitor to the AC power supply on the input side. And a vessel, current inverters apparatus characterized by the slope of the time inversion and to adjust the load current by variably setting the amount of regeneration of the charging energy.