KR100440393B1 - 3 Phase Step Down AC Regulator - Google Patents

Abstract

The present invention is to provide a three-phase step-down AC voltage control device capable of linearly and precisely controlling the AC output voltage applied to the load by appropriately stepping down the three-phase input voltage with a fast response characteristics and high efficiency. To this end, the three-phase step-down AC voltage control apparatus according to the present invention, step-down three-phase AC input of the R-phase, S-phase and T-phase, and outputs three-phase AC to the load side of the U-phase, V-phase and W-phase An AC voltage control device comprising: a first transformer having a secondary side connected between an R-phase AC input and a U-phase AC output; A second transformer having a secondary side connected between the S-phase AC input and the V-phase AC output; A third transformer having a secondary side connected between the T-phase AC input and the W-phase AC output; A control connected to a primary side of the first to third transformers to apply a voltage to the primary sides of the first to third transformers in a direction of decreasing a voltage flowing from the secondary side of the first to third transformers to the load side; It comprises a means.

Description

Three Phase Step Down AC Voltage Controller {3 Phase Step Down AC Regulator}

The present invention relates to a three-phase step-down AC voltage control device, and more particularly, to a three-phase step-down AC voltage control device that linearly controls an AC output voltage applied to a load stage by appropriately stepping down a three-phase input voltage. It is about.

The conventional method for AC voltage control uses a method of switching a tap of a multi-tap transformer into a semiconductor device to control an input voltage. In this case, the number of taps and the number of semiconductor switching elements increases for precise voltage control, and the response time is limited because the tap switching should be made at the moment when the input voltage becomes zero, and the output voltage is controlled discretely with respect to the input voltage variation. This exists.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned conventional problems, and is capable of linearly and precisely controlling an AC output voltage applied to a load stage by appropriately stepping down a three-phase input voltage with fast response characteristics and high efficiency. The purpose is to provide a phase step-down AC voltage control device.

In order to achieve the above object, the three-phase step-down AC voltage control device according to the present invention steps down three-phase AC inputs of R phase, S phase, and T phase, and transfers three-phase AC phase of U phase, V phase, and W phase to the load side. A three-phase step-down AC voltage control device for outputting, comprising: a first transformer having a secondary side connected between an R-phase AC input and a U-phase AC output; A second transformer having a secondary side connected between the S-phase AC input and the V-phase AC output; A third transformer having a secondary side connected between the T-phase AC input and the W-phase AC output; A control connected to a primary side of the first to third transformers to apply a voltage to the primary sides of the first to third transformers in a direction of decreasing a voltage flowing from the secondary side of the first to third transformers to the load side; It characterized in that it comprises a means.

The first transformer is connected to a first output end of the control means, the first end of the primary side of which is connected to a second output end of the control means, and the primary side of the second transformer. Is connected in common with the first stage and the S-phase AC input terminal of the first transformer, and the first stage of the primary side is commonly connected to the third output terminal of the control means and the second stage of the primary side of the second transformer. The second end of the primary side is commonly connected to the first output end of the control means and the first end of the primary side of the first transformer.

The control means is configured to determine the voltage applied to the primary side of the first to third transformers based on the output voltage and the target output voltage.

The control means is provided between the first end of the primary side of the first transformer and the R phase AC input terminal to form a current path to the R phase AC input terminal and the primary side of the first transformer according to a control signal. A first switching circuit; A second switching connected in parallel between a first end and a second end of the primary side of the first transformer to form a current path from the first end of the primary side of the first transformer to the S phase AC input terminal according to a control signal; Circuits; Connected in parallel between the first stage of the primary side of the third transformer and the first stage of the second transformer, forming a current path from the first stage of the primary side of the third transformer to the S phase AC input stage in accordance with a control signal. A third switching circuit to make; A fourth switching circuit provided between the first end of the primary side of the third transformer and the T phase AC input terminal to form a current path to the primary phase of the T phase AC input terminal and the third transformer according to a control signal; It is configured to include.

The control means includes: a first harmonic filter for removing harmonic components of a voltage applied from the first output terminal to the primary side of the first transformer; And a second harmonic filter for removing harmonic components of the voltage applied from the third output terminal to the primary side of the second transformer.

The control means further includes an overcurrent protection circuit for separating the first to fourth switching circuits from the first to third transformers during overcurrent from the three-phase AC input terminal. Here, the overcurrent protection circuit includes: a first switch for opening and closing a current path between the contacts of the first and second switching circuits and the primary side of the first transformer; A second switch connected between the first end of the primary side of the first transformer and the S-phase AC input end; A third switch connected between the first end of the primary side of the third transformer and the S-phase AC input end; A fourth switch for opening and closing a current path between the contacts of the third and fourth switching circuits and the primary side of the third transformer; An overcurrent detector for detecting an overcurrent of the three-phase AC input terminal; Outputs a control signal from the overcurrent detector to turn off the first and third switches when the overcurrent is detected to cut off the current path and to turn the second and fourth switches on. To form a current path, and output a control signal to turn on the first and third switches when the overcurrent is not detected by the overcurrent detection unit to form a current path, and at the same time, the second and fourth And a control signal generator for outputting a control signal for turning off the switch to cut off the current path.

In the first embodiment of the present invention, the first switching circuit is a parallel circuit of the first semiconductor switching element and the first diode, the parallel circuit of the second semiconductor switching element and the second diode is connected in series, The second switching circuit is a parallel circuit of the third semiconductor switching device and the third diode, the parallel circuit of the fourth semiconductor switching device and the fourth diode is connected in series, and the third switching circuit is connected to the fifth semiconductor switching device The parallel circuit of the fifth diode and the parallel circuit of the sixth semiconductor switching element and the sixth diode are connected in series, and the fourth switching circuit is the parallel circuit of the seventh semiconductor switching element and the seventh diode, and the eighth semiconductor. The switching element and the parallel circuit of the eighth diode are connected in series.

In the first embodiment of the present invention, the control means detects the voltage polarity between the R-phase AC input terminal and the S-phase AC input terminal and outputs a first voltage polarity signal and a first voltage polarity inversion signal which is an inverted signal thereof. A first voltage polarity detector; A second voltage polarity detector for detecting a voltage polarity between the T-phase AC input terminal and the S-phase AC input terminal and outputting a second voltage polarity signal and a second voltage polarity inversion signal corresponding to the inverted signal; A pulse width modulation signal generator for modulating a pulse width based on the output voltage and a target voltage and outputting a pulse width modulation signal and a pulse width modulation inversion signal thereof, the pulse width modulation signal; And a switching signal generator for outputting a switching control signal applied to the first to eighth semiconductor switching elements based on output signals of the first and second voltage polarity detectors and the pulse width modulation signal generator.

In the first embodiment of the present invention, the switching signal generator outputs a logic sum signal of the pulse width modulation signal and the first voltage polarity inversion signal as a control signal of the first semiconductor switching element, and the pulse width modulation signal. And output the logic sum signal of the first voltage polarity signal as a control signal of the second semiconductor switching element, and the logic sum signal of the pulse width modulation inversion signal and the first voltage polarity inversion signal as the control signal of the third semiconductor switching element. Outputting a logic sum signal of the pulse width modulation inversion signal and the first voltage polarity signal as a control signal of a fourth semiconductor switching element, and outputting a logic sum signal of the pulse width modulation inversion signal and the second voltage polarity signal; And a logic sum signal of the pulse width modulation inversion signal and the second voltage polarity inversion signal, as a control signal of a five semiconductor switching element. Outputs a control sum of the pulse width modulation signal and the second voltage polarity signal as a control signal of the seventh semiconductor switching element, and outputs a logic sum of the pulse width modulation signal and the second voltage polarity inversion signal. The signal is output as a control signal of the eighth semiconductor switching element.

In the second embodiment of the present invention, the first switching circuit is formed by connecting a first semiconductor switching element between two diode series circuits in which cathodes are connected to each other and two diode series circuits in which anodes are connected to each other, The second switching circuit is formed by connecting a second semiconductor switching element between two diode series circuits in which cathodes are connected to each other and two diode series circuits in which anodes are connected to each other, and wherein the third switching circuit is connected to the cathodes. A third semiconductor switching element is connected between two diode series circuits and two diode series circuits in which the anodes are connected to each other, and the fourth switching circuit includes two diode series circuits in which the cathodes are connected to each other and an anode of each other. The fourth semiconductor switching element is connected between the two connected diode series circuits.

In the second embodiment of the present invention, the pulse width modulated signal generator further outputs a pulse width modulated signal and a pulse width modulated inverted signal which is an inverted signal by modulating the pulse width based on the output voltage and the target voltage. And the pulse width modulation signal is applied as a switching control signal of the first and fourth semiconductor switching elements, and the pulse width modulation inversion signal is applied as a switching control signal of the second and third semiconductor switching elements.

1 is a circuit diagram of a three-phase step-down AC voltage control device according to a first embodiment of the present invention;

2 is a block diagram of a switching signal generation configuration of each switch of FIG.

3 is a waveform diagram illustrating a switching signal waveform of FIG. 2;

4 is a circuit diagram of a three-phase step-down AC voltage control device according to a second embodiment of the present invention;

5 is a block diagram of a switching signal generation configuration of each switch of FIG. 4;

6 is a waveform diagram illustrating the switching signal waveform of FIG. 5.

※ Explanation of code for main part of drawing

10, 12: voltage polarity detector 14: pulse width modulation (PWM) signal generator

16: first switching signal generator 18-22: overcurrent detector

24: second switching signal generator R, S, T: three-phase AC input terminal

U, V, W: 3-phase AC output terminal C1 ~ C7: Capacitor

L1, L2: Reactor TR1, TR2, TR3: Series Compensation Transformer

T1 ~ T8: semiconductor switching element (transistor) D1 ~ D16: diode

SW1 ~ SW4: Switch

Hereinafter, a three-phase step-down AC voltage control apparatus according to a preferred embodiment of the present invention will be described with reference to the accompanying drawings.

1 is a circuit configuration diagram of a three-phase step-down AC voltage control apparatus according to a first embodiment of the present invention, Figure 2 is a block diagram of the configuration of the switching signal of each switch of Figure 1, Figure 3 and Figures 1 and 2 Is a waveform diagram for explaining a switching signal waveform.

As shown in Fig. 1, in this embodiment, the secondary sides of the transformers TR1, TR2, TR3 are connected in series to the three-phase AC input terminals R, S, T, respectively, and the transformers TR1, TR2, TR3. ) Is connected to the switching element series circuits T1 to T4, D1 to D4 (T5 to T8, D5 to D8) via harmonic filters L1 and C3 (L2 and C4).

The switching device serial circuits T1 to T4 and D1 to D4 are connected in parallel to the R-phase AC input terminal R and the S-phase AC input terminal S, and the switching device serial circuits T5 to T8 and D5 to D8. Is connected in parallel to the T-phase AC input terminal T and the S-phase AC input terminal S. In addition, an input voltage filter capacitor C1 for filtering an input voltage between an R-phase and an S-phase AC input terminal is connected to the switching element series circuits T1 to T4 and D1 to D4 in parallel. An input voltage filter capacitor C2 for filtering the input voltage between the T-phase and S-phase AC input terminals is connected in parallel to T5 to T8 and D5 to D8.

The switching device series circuits T1 to T4 and D1 to D4 may include a semiconductor switching device (wherein the semiconductor switching device may include an IGBT (Insulated Gate Bipolar Transistor) or an FET as a transistor) and a first to first diodes. 4 switching parallel circuits (T1, D1) (T2, D2) (T3, D3) (T4, D4) are connected in series, and the switching device series circuits (T5-T8, D5-D8) are also semiconductor switching elements and diodes. The fifth to eighth switching parallel circuits T5 and D5 (T6 and D6) and T7 and D7 (T8 and D8) formed in series are connected in series.

The connection points of the second switching parallel circuits T2 and D2 and the third switching parallel circuits T3 and D3 of the switching element series circuits T1 to T4 and D1 to D4 are the first switch SW1 and the harmonic filter L1. Is connected to the primary side of the first transformer TR1 via C3, and the third switching parallel circuit T3 and D3 and the third switching parallel circuit are connected to the connection point of the first switch SW1 and the harmonic filters L1 and C3. The second switch SW2 is connected in parallel to the four switching parallel circuits T4 and D4.

The connection points of the sixth switching parallel circuits T6 and D6 and the seventh switching parallel circuits T7 and D7 of the switching element series circuits T5 to T8 and D5 to D8 are the third switch SW3 and the harmonic filter L2. Is connected to the primary side of the second transformer TR2 via C4, and a seventh switching parallel circuit T7, D7 and a seventh switching point are connected to the connection point of the third switch SW3 and the harmonic filters L2, C4. The fourth switch SW4 is connected in parallel to the eight switching parallel circuits T8 and D8.

The output voltage filter capacitors C5 to C7 for filtering the AC output voltage are connected to the three-phase AC output terminals U, V, and W. A load is applied to the lower end of the output voltage filter capacitors C5 to C7. Connected.

The configuration for generating the switching signals S1 to S8 applied to the first to eighth switching parallel circuits T1 and D1 to T8 and D8 is as illustrated in FIG. 2. If the polarity of the voltage V _RS between the R-phase AC input R and the S-phase AC input S in R, S, and T is detected, and the voltage V _RS is positive as shown in FIG. A high voltage and low level V_RS signal, a first voltage polarity detector 10 for outputting a / V_RS signal which is an inverted signal of the V_RS signal, a T phase AC input T and an S phase AC input S A second voltage polarity detector for detecting the polarity of the voltage V _TS between the V_TS signal when the voltage V _TS is positive and low level when the voltage V _TS is positive and / V_TS signal which is an inverted signal of the V_TS signal. (12) and PWM signal generation which modulates the pulse width according to the difference between the target voltage and the output voltage to generate a pulse width modulated signal PWM signal and its inverted signal / PWM as shown in FIG. 14, output signals V_RS, / V_RS, V_TS, / V_TS of the first and second voltage polarity detectors 10 and 12 and output signals PWM and / PWM of the PWM signal generator 14; The first switching signal generation unit 16 generates and outputs the switching control signals S1 to S8 using the < RTI ID = 0.0 >

Here, the switching signal (S1) is a signal generated by the logical operation of the PWM signal and / V_RS signal, the switching signal (S2) is a signal generated by the logical operation of the PWM signal and V_RS signal, the switching signal S3 is a signal generated by the logical sum of the / PWM signal and the / V_RS signal, and the switching signal S4 is a signal generated by the logical sum of the / PWM signal and the V_RS signal, and the switching signal S5. Is a signal generated by the logical operation of the PWM signal and the / V_TS signal, the switching signal (S6) is a signal generated by the logical operation of the PWM signal and the V_TS signal, the switching signal (S7) and / PWM signal A signal generated by the logical sum operation of the / V_RS signal, and the switching signal (S8) is a signal generated by the logical sum operation of the / PWM signal and the V_TS signal.

The configuration for generating a switching signal applied to the first to fourth switches SW1 to SW4 detects an overcurrent at each stage of the three-phase AC input terminals R, S, and T, as shown in FIG. Generates a switching control signal applied to the first to fourth switches SW1 to SW4 by receiving the overcurrent detectors 18 to 22, the detection signals of the overcurrent detectors 18 to 22, and the initial drive signal of the apparatus. And a second switching signal generator 24 for outputting.

Here, the second switching signal generator 24 is the first and the third switch (SW1, SW3) is turned off (OFF) until the control circuit configuration of the device is stabilized at the time of initial operation of the device and the second and Outputs a control signal for the fourth switches SW2 and SW4 to be turned ON, and thereafter, when a predetermined time elapses after the control circuit configuration is stabilized, the first and third switches SW1 and SW3 are turned on ( And a control signal for turning off the second and fourth switches SW2 and SW4. Here, the switch (1) to prevent the first to eighth switching parallel circuits (T1, D1) to (T8, D8) from being damaged by the induced power from the secondary side of the transformers (TR1 to TR3) at the initial operation of the device. It turns off SW1) (SW3).

When the overcurrent is detected from the overcurrent detectors 18 to 22, the second switching signal generator 24 damages the first to eighth switching parallel circuits T1, D1 to T8, D8 by the overcurrent. Outputs a control signal to turn the first and third switches SW1 and SW3 off and to turn the second and fourth switches SW2 and SW4 on. do.

Referring to the operation of the three-phase step-down AC voltage control apparatus according to the first embodiment of the present invention configured as described above are as follows.

<Super start up and over current detection>

Since the switches SW1 and SW3 are in the OFF state and the switches SW2 and SW4 are in the ON state, the switching parallel circuits T1 to T8, D1 to D8 and the harmonic filter L1 are supplied from the three-phase AC input terminals R, S and T. The current path leading to the primary sides of the transformers TR1 to TR3 is interrupted via the C3, L2 and C4, and the current induced from the secondary side of the transformers TR1 to TR3 to the primary side is harmonic filter L1, C3) (L2, C4) and the switch (SW2) (SW4) flows to the S-phase AC input terminal. Therefore, damage to the switching parallel circuits T1 to T8, D1 to D8 is caused by overcurrent and overvoltage before the control circuit of the device is secured and when overcurrent flows through the three-phase AC input terminals R, S and T. Will be prevented.

<Normal operation>

Since the switches SW1 and SW3 are on and the switches SW2 and SW4 are off, the switching parallel circuits T1 to T8, D1 to D8 and the harmonic filter L1 are supplied from the three-phase AC input terminals R, S and T. A current path leading to the primary sides of the transformers TR1 to TR3 is formed via the C3, L2 and C4, and the current induced from the secondary side of the transformers TR1 to TR3 to the primary side is harmonic filter L1, A current path flowing to the S-phase AC input terminal is also formed via C3) (L2, C4) and the switching parallel circuits T1 to T8, D1 to D8.

Time t1

Since the semiconductor switching element T1 is in the off state, the current path from the R-phase AC input terminal R to the switching parallel circuit is interrupted, and the voltage applied to the primary side of the transformer TR1 becomes 0V.

In addition, since the semiconductor switching element T6 is in the off state, the current path from the T-phase AC input terminal R to the switching parallel circuit is interrupted, and the voltage applied to the primary side of the transformer TR3 becomes 0V.

Time t2

Since the semiconductor switching elements T1 and T2 are on and the semiconductor switching elements T3 are off, the voltage from the R-phase AC input terminal R passes through the harmonic filters L1 and C3 to the primary side of the transformer TR1. In this case, a voltage smoothed according to the duty ratio of the pulse width modulation signal is applied to the primary side of the transformer TR1, and a predetermined voltage is induced in the direction of decreasing the R phase voltage on the secondary side of the transformer by the applied voltage. do. Accordingly, the output voltage output to the U phase is stepped down by the predetermined voltage.

In addition, since the semiconductor switching elements T5 and T6 are in the on state and the semiconductor switching element T8 is in the off state, voltages from the S-phase AC input terminal S are harmonic filters C4 and L2, and the sixth and fifth switching parallel circuits. It is applied to the secondary side of the transformer TR3 via (T6, D6) (T5, D5), and at this time, a voltage smoothed according to the duty ratio of the pulse width modulation signal is applied to the secondary side of the transformer TR3. The applied voltage is a predetermined voltage in the direction of increasing the T-phase voltage on the transformer secondary side. As a result, the output voltage output to the W phase is stepped down by the predetermined voltage.

That is, between the time points t1 and t11 (the section where V _RS is + polar), a predetermined voltage is induced in the direction of decreasing the R-phase voltage on the secondary side of the transformer TR1 according to the duty ratio of the PWM pulses, and at time t12, t22. Between the sections where V _RS is -polar, a predetermined voltage is applied in the direction of increasing the R-phase voltage at the secondary side of the transformer TR1 according to the duty ratio of the PWM pulses, thereby lowering the R-phase voltage as a whole to the U-phase voltage. Will print

On the other hand, at a time t1 to t7 and a time t19 to t22 (a section in which V _TS is -polar), a predetermined voltage is applied in the direction of increasing the T phase voltage at the secondary side of the transformer TR3 according to the duty ratio of the PWM pulses. and, it is a predetermined voltage induced at a time point t8 in the direction of reducing the T-phase voltage in the secondary side of the transformer (TR1) in accordance with the duty ratio of the PWM pulse in between t18 (V _TS is + polar region), the whole T-phase voltage Dropping to output W phase voltage.

As described above, according to the three-phase step-down AC voltage control device according to the first embodiment of the present invention, the pulse width modulation method is performed by the pulse width modulation method based on the difference between the preset command voltage and the output voltage to generate a desired output voltage. In the switching signal generator 16, the switching element series circuits T1, D1, T2, D2, T3, D3, T4, D4, T5, D5, T6, D6, T7, D7, T8, D8) is controlled and the compensating voltage is generated by directly chopping the input voltages of the two phases of the three-phase input exchange voltage. The AC PWM voltage generated as described above is converted into a sinusoidal AC voltage by the harmonic filter units L1 and C3 (L2 and C4), and a compensation voltage corresponding to the voltage width to be stepped down through the transformers TR1 to TR3 is input voltage. In the opposite direction, the output voltage can be kept low to a desired level to achieve power savings. At this time, a constant current is regenerated from the transformers TR1 to TR3 to the power supply side for power reduction.

In the first embodiment, switching element series circuits T1 and D1 (T2 and D2) (T3 and D3) (T4 and D4) (T5 and D5) (T6, D6) (T7, D7) (T8, D8) using a new method consisting of an AC chopper and three transformers (TR1 to TR3) to generate a compensation voltage to control the output voltage lower than the input voltage to save power It is a three-phase step-down AC voltage control device that can be achieved, the response time is superior and the efficiency is higher than the conventional tap switching method. In addition, in the conventional tap-changing method, as the voltage fluctuation range is precisely required, more taps and semiconductor switch elements are required, but in the case of the above-described embodiment, a precise voltage control is possible with a fixed number of semiconductor switching elements and the size of the transformer increases in proportion to the capacity. And the weight is removed has the advantage that can significantly reduce the size of the three-phase step-down AC voltage control device compared to the conventional method.

In addition, by applying PWM logic to enable stable operation of the AC chopper, which is a switching device series circuit, the semiconductor switching device is protected regardless of the type of load.

4 is a circuit diagram of a three-phase step-down AC voltage control device according to a second embodiment of the present invention, FIG. 5 is a block diagram of a switching signal generation configuration of each switch of FIG. 4, and FIG. 5 is a waveform diagram for explaining the switching signal waveform.

As shown in FIG. 4, in this embodiment, the secondary sides of the transformers TR1, TR2, TR3 are connected in series to the three-phase AC input terminals R, S, and T, respectively, and the transformers TR1, TR2, TR3. ) Is connected to the switching element series circuits T1-T2, D1-D8 (T3-T4, D9-D16) via harmonic filters L1, C3 (L2, C4).

The switching device series circuits T1 to T2 and D1 to D8 are connected in parallel to the R phase AC input terminal R and the S phase AC input terminal S, and the switching device series circuits T3 to T4 and D9 to D16. Is connected in parallel to the T-phase AC input terminal (T) and the S-phase AC input terminal (S). In addition, an input voltage filter capacitor C1 for filtering an input voltage between an R-phase and an S-phase AC input terminal is connected in parallel to the switching element series circuits T1 to T2 and D1 to D8. In (T3 to T4, D9 to D16), an input voltage filter capacitor C2 for filtering the input voltage between the T-phase and S-phase AC input terminals is connected in parallel.

The switching device series circuits T1 to T2 and D1 to D8 have first and second switching parallel circuits T1, D1 to D4 (T2, D5 to D8) made of a semiconductor switching element and a diode connected in series. The switching device serial circuits T3 to T4 and D9 to D16 also have a third and fourth switching parallel circuits T3, D9 to D12 (T4, D13 to D16) each formed of a semiconductor switching element and a diode.

The connection points of the first switching parallel circuits T1, D1-D4 and the second switching parallel circuits T2, D5-D8 of the switching element series circuits T1-T2, D1-D8 are connected to the first switch SW1. It is connected to the primary side of the first transformer TR1 via the harmonic filters L1, C3, and the second switching parallel circuit T2, at the connection point of the first switch SW1 and the harmonic filters L1, C3. The second switch SW2 is connected in parallel to D5 to D8).

The connection points of the third switching parallel circuits T3, D9 to D12 and the third switching parallel circuits T4, D13 to D16 of the switching element series circuits T3 to T4 and D9 to D16 are connected to the third switch SW3. It is connected to the primary side of the second transformer TR2 via the harmonic filters L2, C4, and the third switching parallel circuit T3, at the connection point of the third switch SW3 and the harmonic filters L3, C4. The fourth switch SW4 is connected in parallel to D9 to D12.

The output voltage filter capacitors C5 to C7 for filtering the AC output voltage are connected to the three-phase AC output terminals U, V, and W. A load is applied to the lower end of the output voltage filter capacitors C5 to C7. Connected.

Generating switching signals S1 to S4 applied to the first to fourth switching parallel circuits T1, D1 to D4, T2, D5 to D8, T3, D9 to D12, and T4, D13 to D16. 5, the pulse width is modulated by the difference between the target voltage and the output voltage to generate a pulse width modulated signal PWM signal and its inverted signal / PWM as shown in FIG. It is configured to include a PWM signal generating unit 14 to. The pulse width modulation signal PWM is applied as a switching control signal of the first switching parallel circuits T1, D1 to D4 and the fourth switching parallel circuits T4, D13 to D16, and the inverted signal / PWM. The signal is applied as a switching control signal of the second switching parallel circuits T2, D5 to D8 and the third switching parallel circuits T3, D9 to D12.

The configuration for generating a switching signal applied to the first to fourth switches SW1 to SW4 detects an overcurrent at each stage of the three-phase AC input terminals R, S, and T, as shown in FIG. Generates a switching control signal applied to the first to fourth switches SW1 to SW4 by receiving the overcurrent detectors 18 to 22, the detection signals of the overcurrent detectors 18 to 22, and the initial drive signal of the apparatus. And a second switching signal generator 24 for outputting.

Here, the second switching signal generator 24 operates in the same manner as in the first embodiment.

Referring to the operation of the three-phase step-down AC voltage control device according to a second embodiment of the present invention configured as described above are as follows.

<Super start up and over current detection>

Since the switches SW1 and SW3 are in the OFF state and the switches SW2 and SW4 are in the ON state, the switching parallel circuits T1 to T4, D1 to D16 and the harmonic filter L1 are connected from the three-phase AC input terminals R, S and T. The current path leading to the primary sides of the transformers TR1 to TR3 is interrupted via the C3 L2 and C4, and the current induced from the secondary side of the transformers TR1 to TR3 to the primary side is harmonic filter L1, C3) (L2, C4) and the switch (SW2) (SW4) flows to the S-phase AC input terminal. Therefore, damage to the switching parallel circuits T1 to T4, D1 to D16 is prevented by overcurrent and overvoltage before the control circuit of the device is secured and when overcurrent flows to the three-phase AC input terminals R, S and T. Will be prevented.

<Normal operation>

Since the switches SW1 and SW3 are on and the switches SW2 and SW4 are off, the switching parallel circuits T1 to T4, D1 to D16 and the harmonic filter L1 are supplied from the three-phase AC input terminals R, S and T. A current path leading to the primary sides of the transformers TR1 to TR3 is formed via the C3, L2 and C4, and the current induced from the secondary side of the transformers TR1 to TR3 to the primary side is harmonic filter L1, A current path flowing to the S-phase AC input terminal via C3) (L2, C4) and the switching parallel circuits T1 to T4, D1 to D16 is also formed.

Time t1

Since the semiconductor switching elements T1 and T2 are in the off state, the current path from the R-phase AC input terminal R to the switching parallel circuit is cut off, and the voltage applied to the primary side of the transformer TR1 becomes 0V.

In addition, since the semiconductor switching elements T3 and T4 are in the off state, the current path from the T-phase AC input terminal T to the switching parallel circuit is interrupted, and the voltage applied to the primary side of the transformer TR3 becomes 0V.

Time t2

Since the semiconductor switching element T1 is in the on state and the semiconductor switching element T2 is in the off state, the voltage from the R-phase AC input terminal R is applied to the primary side of the transformer TR1 via the harmonic filters L1 and C3. In this case, a voltage smoothed according to the duty ratio of the pulse width modulation signal is applied to the primary side of the transformer TR1, and a predetermined voltage is induced in the direction of decreasing the R phase voltage on the secondary side of the transformer by the applied voltage. Accordingly, the output voltage output to the U phase is stepped down by the predetermined voltage.

In addition, since the semiconductor switching element T4 is in the on state and the semiconductor switching element T3 is in the off state, the voltage from the T-phase AC input terminal T passes through the harmonic filters L2 and C4 to the primary side of the transformer TR3. In this case, a voltage smoothed in accordance with the duty ratio of the pulse width modulation signal is applied to the primary side of the transformer TR3, and in the direction of decreasing the T phase voltage on the secondary side of the transformer TR3 by the applied voltage. The predetermined voltage is induced. As a result, the output voltage output to the W phase is stepped down by the predetermined voltage.

That is, between the time points t1 and t11 (the section where V _RS is + polar), a predetermined voltage is induced in the direction of decreasing the R-phase voltage on the secondary side of the transformer TR1 according to the duty ratio of the PWM pulses, and at time t12, t22. Between the sections where V _RS is -polar, a predetermined voltage is applied in the direction of increasing the R-phase voltage at the secondary side of the transformer TR1 according to the duty ratio of the PWM pulses, thereby lowering the R-phase voltage as a whole to the U-phase voltage. Will print

On the other hand, at a time point t1 to t7 and a time point t19 to t22 (a section in which V _TS is + polarity), a predetermined voltage is induced in a direction of decreasing the T phase voltage on the secondary side of the transformer TR1 according to the duty ratio of the PWM pulse. and, t18 at time t8 - is a predetermined voltage in the direction of expanding the T-phase voltage in the secondary side of a transformer (TR3) in accordance with the duty ratio of the PWM pulse in between (V _TS is polar zone) is applied, a T-phase voltage It drops and outputs W-phase voltage.

As described above, according to the three-phase step-down AC voltage control device according to the second embodiment, the same effects as those of the first embodiment can be achieved, and the circuit configuration can be simplified rather than the first embodiment. You can do it.

On the other hand, the present invention is not limited to the above-described typical preferred embodiments, but can be carried out in various ways without departing from the gist of the present invention, various modifications, alterations, substitutions or additions are common in the art Those who have knowledge will easily understand. If the implementation by such improvement, change, replacement or addition falls within the scope of the appended claims, the technical idea should also be regarded as belonging to the present invention.

As described in detail above, according to the present invention, it is applied to industrial group lighting such as road lighting, manufacturing plants, workshops, supermarkets, and office lighting such as public offices, so that the input voltage input to the lighting apparatus at a time when high illumination is not required is appropriate. Power saving can be achieved by stepping down.

To this end, by adding an AC chopper and a series compensating transformer, which are switching circuits in series, the AC chopper generates a compensation voltage corresponding to the amount of the input voltage to be reduced, which is compensated for the input voltage through the transformer and the output voltage is stepped down. Power savings will be achieved.

Therefore, it is possible to control high-quality voltage that always outputs a constant voltage even within the fluctuation range of input voltage, and has the advantage of excellent response time and efficiency. In the control of the AC compensator of the series compensation method, since a high voltage may be generated on the primary side of the serial compensating transformer when all the switches are turned off, measures to protect the AC chopper switch are necessary. As the current flows, the pulse width modulation method is adopted to operate the switch so that the current can be fed back to the input power. In the present invention, it is possible to properly configure the pulse width modulation method applied to each switch according to the polarity of the input voltage and the polarity of the PWM application waveform to maintain the flow of current.

Claims (13)

In the three-phase step-down AC voltage control device for stepping down the three-phase AC input of the R-phase, S-phase, and T-phase, and outputting three-phase AC to the load side of the U-phase, V-phase, and W-phase, A first transformer having a secondary side connected between the R phase AC input and the U phase AC output; A second transformer having a secondary side connected between the S-phase AC input and the V-phase AC output; A third transformer having a secondary side connected between the T-phase AC input and the W-phase AC output; A first switching circuit provided between the first end of the primary side of the first transformer and the R phase AC input terminal and forming a current path to the R phase AC input terminal and the primary side of the first transformer according to a control signal; ; A second switching connected in parallel between a first end and a second end of the primary side of the first transformer to form a current path from the first end of the primary side of the first transformer to the S phase AC input terminal according to a control signal; Circuits; Connected in parallel between the first stage of the primary side of the third transformer and the first stage of the second transformer, forming a current path from the first stage of the primary side of the third transformer to the S phase AC input stage in accordance with a control signal. A third switching circuit to make; A fourth switching circuit provided between the first end of the third side of the third transformer and the T phase AC input end to form a current path to the T phase AC input end and the primary side of the third transformer according to a control signal; ; A first voltage polarity detector for detecting a voltage polarity between the R-phase AC input terminal and the S-phase AC input terminal and outputting a first voltage polarity signal and a first voltage polarity inversion signal corresponding to the inverted signal; A second voltage polarity detector for detecting a voltage polarity between the T-phase AC input terminal and the S-phase AC input terminal and outputting a second voltage polarity signal and a second voltage polarity inversion signal corresponding to the inverted signal; A pulse width modulation signal generator for modulating a pulse width based on the output voltage and a target voltage and outputting a pulse width modulation signal and a pulse width modulation inversion signal thereof, the pulse width modulation signal; A switching signal generator for outputting a switching control signal applied to the first to fourth switching circuits based on output signals of the first and second voltage polarity detectors and the pulse width modulation signal generator; And an overcurrent protection circuit for separating the first to fourth switching circuits from the first to third transformers during an overcurrent from the three-phase AC input terminal. delete The method of claim 2, The first to fourth switching circuits are configured to determine the voltage applied to the primary side of the first to third transformer based on the output voltage and the target output voltage. . delete The method of claim 1, A first harmonic filter for removing harmonic components of the voltage applied from the first output stage to the primary side of the first transformer; And a second harmonic filter for removing harmonic components of the voltage applied from the third output terminal to the primary side of the second transformer. delete The method of claim 1, The overcurrent protection circuit, A first switch for opening and closing a current path between the contacts of the first and second switching circuits and the primary side of the first transformer; A second switch connected between the first end of the primary side of the first transformer and the S-phase AC input end; A third switch connected between the first end of the primary side of the third transformer and the S-phase AC input end; A fourth switch for opening and closing a current path between the contacts of the third and fourth switching circuits and the primary side of the third transformer; An overcurrent detector for detecting an overcurrent of the three-phase AC input terminal; Outputs a control signal from the overcurrent detector to turn off the first and third switches when the overcurrent is detected to cut off the current path and to turn the second and fourth switches on. To form a current path, and output a control signal to turn on the first and third switches when the overcurrent is not detected by the overcurrent detection unit to form a current path, and at the same time, the second and fourth And a control signal generator for outputting a control signal to turn off the switch to cut off the current path. The method of claim 7, wherein The control signal generation unit receives an initial drive signal of the device and outputs a control signal for turning off the first and third TM positions for a predetermined time immediately after the operation of the device is interrupted to cut off the current passage and at the same time. And outputting a control signal for turning the fourth switch on, thereby forming a current path, and outputting a control signal for turning the first and third switches on after the predetermined time has elapsed. And outputting a control signal to turn off the second and fourth switches to turn off the current path to cut off the current path. The method of claim 1, The first switching circuit is formed by connecting a parallel circuit of a first semiconductor switching element and a first diode, and a parallel circuit of a second semiconductor switching element and a second diode. The second switching circuit is formed by connecting a parallel circuit of a third semiconductor switching element and a third diode, and a parallel circuit of a fourth semiconductor switching element and a fourth diode. The third switching circuit is a parallel circuit of the fifth semiconductor switching element and the fifth diode, the parallel circuit of the sixth semiconductor switching element and the sixth diode is connected in series, The fourth switching circuit is a three-phase step-down AC voltage control device, characterized in that the parallel circuit of the seventh semiconductor switching element and the seventh diode, the parallel circuit of the eighth semiconductor switching element and the eighth diode is connected in series. delete The method of claim 9, The switching signal generator outputs a logic sum signal of the pulse width modulation signal and the first voltage polarity inversion signal as a control signal of a first semiconductor switching element, and includes a logic sum signal of the pulse width modulation signal and the first voltage polarity signal. Is output as a control signal of the second semiconductor switching element, and a logic sum signal of the pulse width modulation inversion signal and the first voltage polarity inversion signal is output as a control signal of the third semiconductor switching element, and the pulse width modulation inversion signal and Outputting a logic sum signal of the first voltage polarity signal as a control signal of a fourth semiconductor switching element, and outputting a logic sum signal of the pulse width modulation inversion signal and the second voltage polarity signal as a control signal of a fifth semiconductor switching element; Outputting a logic sum signal of the pulse width modulation inversion signal and the second voltage polarity inversion signal as a control signal of a sixth semiconductor switching element; The logic sum signal of the width modulation signal and the second voltage polarity signal is output as a control signal of the seventh semiconductor switching element, and the logic sum signal of the pulse width modulation signal and the second voltage polarity inversion signal is controlled by the eighth semiconductor switching element. A three-phase step-down AC voltage control device for outputting as a signal. In the three-phase step-down AC voltage control device for stepping down the three-phase AC input of the R-phase, S-phase, and T-phase, and outputting three-phase AC to the load side of the U-phase, V-phase, and W-phase, A first transformer having a secondary side connected between the R phase AC input and the U phase AC output; A second transformer having a secondary side connected between the S-phase AC input and the V-phase AC output; A third transformer having a secondary side connected between the T-phase AC input and the W-phase AC output; It is provided between the first end of the primary side of the first transformer and the R phase AC input terminal, and the cathodes are connected to each other to form a current path to the R phase AC input terminal and the primary side of the first transformer according to a control signal. A first switching circuit comprising a first semiconductor switching element connected between the two diode series circuits and two diode series circuits in which anodes are connected to each other; Connected in parallel between the first stage and the second stage of the primary side of the first transformer, the cathodes of each other to form a current path from the first stage of the primary side of the first transformer to the S phase AC input stage according to a control signal. A second switching circuit in which a second semiconductor switching element is connected between the connected two diode series circuits and two diode series circuits in which anodes are connected to each other; Connected in parallel between the first stage of the primary side of the third transformer and the first stage of the second transformer, forming a current path from the first stage of the primary side of the third transformer to the S phase AC input stage in accordance with a control signal. A third switching circuit in which a third semiconductor switching element is connected between two diode series circuits in which cathodes are connected to each other and two diode series circuits in which anodes are connected to each other so as to be connected to each other; It is provided between the first end of the primary side of the third transformer and the T phase AC input terminal, and the cathodes are connected to each other to form a current path to the primary phase of the T phase AC input terminal and the third transformer according to a control signal. A fourth switching circuit comprising a fourth semiconductor switching element connected between the two diode series circuits and two diode series circuits in which anodes are connected to each other; The pulse width modulated signal is modulated based on the output voltage and the target voltage to apply a pulse width modulated signal as a switching control signal of the first and fourth semiconductor switching elements, and the pulse width modulated inverted signal, the inverted signal, is applied to the second and A three-phase step-down AC voltage control device comprising a pulse width modulation signal generator for applying as a switching control signal of a third semiconductor switching element. delete