KR20000021277U - An automatic voltage regulator - Google Patents

Abstract

The present invention relates to an improved automatic voltage regulator (A.V.R) with improved adjustment accuracy.

The device of the present invention consists of a step-down transformer 200 consisting of one secondary winding and a plurality of primary windings, and triacs T10 and T20 for selecting one of the plurality of primary windings according to a control signal. A voltage adjusting unit for stabilizing the output voltage by adding or subtracting a voltage, the single winding transformer 210, connected between the respective taps of the single winding transformer and the selected primary winding of the step-down transformer, and when turned on according to a control signal, forms a closed circuit to generate a regulated voltage of a predetermined magnitude. The control signal is output to detect the triacs T1 to T8 applied to the voltage adjusting means and the output voltage so that the control voltage is gradually applied in a direction to lower the output voltage if the output voltage is higher than the normal voltage. If it is lower than the normal voltage includes a control circuit 220 for outputting a control signal to apply the adjustment voltage stepwise in the direction of increasing the output voltage; A very simple circuit can double the adjustment accuracy.

Description

Automatic voltage regulator

The present invention relates to an improved automatic voltage regulator (A.V.R) with improved adjustment accuracy.

Automatic voltage regulator (AVR) is a power supply that always maintains the output voltage stable regardless of the input voltage fluctuations, the conventional automatic voltage regulator, as shown in Figure 1, the transformer 100, Single winding transformer 110 having a plurality of tabs, winding resistors R1 to R8 having one end connected to each tab of the single winding transformer, and a triac connected to the winding resistance to open and close each tab of the single winding transformer. T1 to T8, and the control PCB 120 to keep the output voltage stable. Referring to FIG. 1, the primary winding and the secondary winding of the transformer 100 are each composed of one and have a winding ratio of N: 1, and gates of the triacs T1 to T8 for opening and closing each tab of the single winding transformer 110. The terminal is connected to the control PCB 120. The control PCB 120 senses the output voltage, and if the output voltage is higher or lower than the normal voltage, the control PCB 120 drives the gate of the corresponding triac to switch taps to maintain the output voltage stable. In FIG. 1, the triacs 1 to 4 (T1 to T4) are for providing a low regulation voltage, and the triacs 5 to triac 8 (T5 to T8) are for providing a high regulation voltage. A total of 16 regulated voltages can be provided.

However, in the conventional automatic voltage regulator, in order to improve the accuracy of adjustment, it is necessary to increase the tap of the single winding transformer and to increase the switching element for turning on / off the contact point. The manufacture of a single winding is difficult, and there is a problem in that a lot of switching elements are added. In addition, since a short may occur during a tap change in the related art, a winding resistance must be additionally used to prevent a short, and thus there is a problem in that power efficiency is lowered.

Accordingly, the present invention has been made to solve the above-mentioned conventional problems, and an object of the present invention is to provide an improved automatic voltage regulating device capable of doubling the adjustment accuracy with a very simple configuration.

In order to achieve the above object, the apparatus of the present invention, in the automatic voltage regulating device that maintains the output voltage as a reference voltage stably even if the input voltage fluctuates, a step-down transformer consisting of one secondary winding and a plurality of primary windings; And voltage adjusting means configured to select one of the plurality of primary windings according to a control signal to stabilize the output voltage by adding or subtracting an adjustment voltage to the input voltage; A single winding having a high scale winding having a plurality of tabs and inducing a high voltage equal in magnitude between the tabs, and a low scale winding having a plurality of tabs and inducing a low voltage equal in magnitude between the tabs; Switching means connected between the respective taps of the single winding transformer and the selected primary winding of the step-down transformer and turned on according to a control signal to form a closed circuit to apply an adjustment voltage of a predetermined magnitude to the voltage adjusting means; And detecting the output voltage and outputting a control signal to the selection means and the switching means to gradually apply an adjustment voltage in a direction to lower the output voltage when the output voltage is higher than the normal voltage, and when the output voltage is lower than the normal voltage. And control means for outputting a control signal to the selection means and the switching means to apply the adjustment voltage stepwise in the direction of increasing the output voltage.

1 is a schematic diagram showing a conventional automatic voltage regulator;

2 is a view showing an automatic voltage regulator according to the present invention,

3 is a waveform diagram illustrating the present invention,

4 is a flowchart illustrating an operation performed by a CPU according to the present invention.

* Explanation of symbols for main parts of the drawings

200: Step down transformer 202,204,206,212,214,216: Winding

210: single winding transformer 220: control circuit

222: voltage sensing and A-D converter 224: CPU

226: opening and closing inspection unit 228: gate driving unit

T1 ~ T8, T10, T20: Triac

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

2 is a circuit diagram showing an automatic voltage adjusting device according to the present invention, the automatic voltage adjusting device of the present invention is connected to the voltage adjusting means for stabilizing the output voltage by adding or subtracting the adjusting voltage to the input voltage, Single winding transformer 210 having a plurality of taps, a plurality of switching elements (T1 ~ T8) for configuring a closed circuit by connecting each tap of the single winding transformer, control for sensing the output voltage to control the switching element on, off Circuit 220. The voltage adjusting means includes a step-down transformer 200 having a plurality of primary windings 204 and 206 and one secondary winding 202, and a plurality of switching elements for configuring a closed circuit by selecting one of the plurality of primary windings of the step-down transformer. T10, T20).

The single winding transformer 210 has a high scale winding 212 for inducing a relatively high inter-tap voltage (ΔVh) and a low for inducing a relatively low inter-tap voltage (ΔVl) to adjust the adjustment voltage in multiple stages. A scale winding 214, and a winding 216 for providing an induced voltage to the single winding transformer.

In the embodiment of the present invention, the switching elements T1 to T8, T10, and T20 are implemented as a triac TRAIC to open and close the corresponding tap under the control of the CPU 224. The high scale winding 212 and the low scale winding 214 each provide four tap terminals, one end of which is connected to each tap terminal of the triacs T1 to T8, and the other end of the triac is connected in common. Each gate end of the triac is connected to the control circuit 220.

The control circuit 220 drives a voltage sensing and analog-to-digital (AD) converter 222 and gates of each triac T1 to T8, T10, and T20 to detect a change in the output voltage and convert it to digital. According to the output of the gate driver 228, the triac opening and closing inspection unit 226 for checking the opening and closing of each triac (T1 ~ T8, T10, T20), the voltage sensing and AD conversion unit 222 It is composed of a CPU 224 that provides a gate control signal for turning on and off evil and confirms the operation of the triac. The CPU 224 then performs a sequence as shown in FIG. 4 to stabilize the output voltage.

Next, the operation of the present invention configured as described above with reference to Figure 4 as follows.

First, the process of stabilizing the output voltage when the input voltage fluctuates as follows. In general, when the input voltage increases, the output voltage increases accordingly, and when the output voltage increases, the control circuit 220 detects this and drives the triacs T1 to T8, T10, and T20 step-by-step through the step-down transformer ( As shown in (a) of FIG. 3, in 200), the output voltage is lowered by inducing a low adjustment voltage that is in phase with the input voltage. On the contrary, when the input voltage decreases, the output voltage decreases, and when the control circuit detects this, the low adjustment voltage having a phase in phase with the input voltage is induced in the step-down transformer to increase the output voltage as shown in FIG. As such, a change in the output voltage according to the change in the input voltage is immediately sensed, and the control circuit 220 appropriately turns on / off the triac accordingly to stabilize the output voltage by adding or subtracting the adjustment voltage to the input voltage. In FIG. 3A, a denotes an input voltage, b denotes an adjustment voltage, and c denotes that the adjustment voltage is subtracted from the input voltage to make the output voltage lower than the input voltage. In Fig. 3B, a 'denotes an input voltage, b' denotes an adjustment voltage, and c 'denotes that an adjustment voltage is added to the input voltage so that the output voltage becomes higher than the input voltage.

Referring to FIG. 4, in step S1, the CPU is reset after power-on is checked, and in step S2, initialization is performed. Close the Triac 10 (T10) or Triac 20 (T20), Triac 8 (T8), and Triac 1 (T1) during initialization. This initialization process is performed once upon reset or upon initial power-on. Subsequently, after the initialization process, the output voltage is checked in steps S3 and S4, and if the output voltage is normal, the output voltage is continuously checked while keeping T1 and T8 in a closed state.

If the output voltage is higher than the normal voltage (High), check the zero point of the input voltage in step S21, check whether the remaining triac is off in addition to the triac to be turned on in step S22, and then turn on the triac in step S23. To decrease 1 tap in the direction of lowering the voltage. In step S24, it is determined whether the output voltage is normal. If normal, the flow returns to step S3. If not, the flow returns to step S21 to repeat the depressurization process. In this way, the adjustment voltage is subtracted from the input voltage while the tap is changed in steps until the output voltage is normal.

On the contrary, if the output voltage is lower than the normal voltage, the zero point of the input voltage is checked in step S11, the triac is turned off in addition to the triac to be turned on in step S12, and the triac is turned on in step S13. Convert 1 tap in the direction of increasing voltage. In step S14, it is determined whether the output voltage is normal. If normal, the process returns to step S3. If not, the process returns to step S11 to repeat the pressing process. In this way, the tap is changed in steps until the output voltage is normal, and the adjustment voltage is added to the input voltage.

In the embodiment of the present invention, when each triac is turned on, when the corresponding tab is closed, the adjustment voltage is shown in Table 1 below.

Direction tab High scale tap Low-scale tap Adjust voltage (unit: V) Tap 10 Tap 8 Tap 1 + 0 Tap 2 + 1 △ Vl Tap 3 + 2 △ Vl Tap 4 + 3 △ Vl Tap 7 Tap 1 + ΔVh Tap 2 + ΔVh + 1ΔVl Tap 3 + ΔVh + 2 △ Vl Tap 4 + ΔVh + 3 △ Vl Tap 6 Tap 1 + 2 △ Vh Tap 2 + 2 △ Vh + 1 △ Vl Tap 3 + 2 △ Vh + 2 △ Vl Tap 4 + 2 △ Vh + 3 △ Vl Tap 5 Tap 1 + 3 △ Vh Tap 2 + 3 △ Vh + 1 △ Vl Tap 3 + 3 △ Vh + 2 △ Vl Tap 4 + 3 △ Vh + 3 △ Vl Tap 20 Tap 8 Tap 1 -0 Tap 2 -1 △ Vl Tap 3 -2 △ Vl Tap 4 -3 △ Vl Tap 7 Tap 1 -(△ Vh) Tap 2 -(△ Vh + 1 △ Vl) Tap 3 -(△ Vh + 2 △ Vl) Tap 4 -(△ Vh + 3 △ Vl) Tap 6 Tap 1 -(2 △ Vh) Tap 2 -(2ΔVh + 1ΔVl) Tap 3 -(2ΔVh + 2ΔVl) Tap 4 -(2ΔVh + 3ΔVl) Tap 5 Tap 1 -(3 △ Vh) Tap 2 -(3ΔVh + 1ΔVl) Tap 3 -(3ΔVh + 2ΔVl) Tap 4 -(3ΔVh + 3ΔVl)

Referring to Table 1, the voltage applied between each tap in the low-scale winding 214 is "ΔVl", and the voltage applied between each tap in the high-scale winding 212 is "ΔVh". In this case, when T8 and T1 are closed, a "0" V voltage is applied to the primary side of the step-down transformer 200. In the initial state, T8 and T1 are turned on and "ΔVh = 4ΔVl" when the step of each adjustment voltage is "ΔVl". When the winding ratio of the step-down transformer 200 is N: 1, 1 / N of the adjustment voltage is added to or subtracted from the input voltage to stabilize the output voltage.

To explain the operation of the present invention to take a specific numerical value as an example as follows. That is, in the embodiment of the present invention, when the winding ratios Nla: N2 and N1b: N2 of the primary side and the secondary side of the step-down transformer 200 are 4: 1, respectively, and the triac T10 of the primary winding 204 is turned on, The voltage is applied in the direction of increasing the output voltage, and when the triac T20 of the primary winding 206 is turned on, the voltage is applied in the direction of decreasing the output voltage. The voltage? Vh induced between each tap of the high scale winding 212 of the single winding transformer 210 is 40V, and the voltage? Vl induced between each tap of the low scale winding 214 is 10V. The output voltage is 220V for the normal input voltage 220V.

T8 and T1 are turned on in the initialization process (S2), so that the regulated voltage applied to the step-down transformer 200 is 0V. Therefore, when the input AC voltage is 220V, the output voltage is 220V, which is normal.

When the input voltage is changed to 230V and the output voltage is higher than the normal voltage (220V), when the voltage sensing and AD converter 222 detects this and notifies the CPU 224, the CPU 224 sets T10 to lower the output voltage. Turn off and turn on T2 while keeping T8 on. Therefore, the voltage "ΔVl = 10V" is applied to the primary winding 206 of the step-down transformer 200 in the direction of decreasing the input voltage, and 10/4 V = 2.5 in the secondary winding 202 of the step-down transformer. The V voltage appears, resulting in an output voltage as low as 2.5V (ie 230V-2.5 = 227.5V). At this time, in order to protect the circuit element, the tap change is performed when the phase of the input voltage becomes zero.

Then, after re-determining whether the output voltage is normal, if the voltage is still higher than the normal voltage, T3 is turned on by performing tap conversion at the time when it becomes zero. When T3 is on, the adjustment voltage is 20V, so the output voltage is lowered by 5V in the step-down transformer 200 (ie, 230-5 = 225V). Repeat this process to keep the taps closed to ensure that the output voltage is at normal voltage.

On the other hand, when the input voltage is lowered and the output voltage is lowered, the adjustment voltage is added to the input voltage in a direction in which T10 is turned on and T20 is turned off to increase the output voltage. In other words, when the input voltage is changed to 210V while T8 and T1 are turned on, and the voltage sensing and AD converter 222 detects that the output voltage is lower than the normal voltage 220V, the CPU 224 informs the CPU 224. Turn on T2 while keeping T8 on. Therefore, the voltage "ΔVl = 10V" is applied to the primary winding 204 of the step-down transformer in the direction of increasing the input voltage, and 10/4 V = 2.5V in the secondary winding 202 of the step-down transformer. The output voltage is increased by 2.5V (ie 210V + 2.5 = 212.5V). At this time, in order to protect the circuit element, the tap change is performed when the phase of the input voltage becomes zero.

Subsequently, the output voltage is determined to be normal again. If the output voltage is still lower than the normal voltage, T3 is turned on at the time when the output voltage becomes zero. When T3 is on, the adjustment voltage is 20V, so the output voltage is increased by 5V in the step-down transformer 200 (ie 210 + 5 = 215V). Repeat this process to switch taps in stages until the output voltage reaches a normal voltage.

As described above, the automatic voltage regulating device according to the present invention uses a plurality of primary windings of a transformer for regulating voltage, and a single winding transformer having a plurality of taps is connected to a selected one of the plurality of windings to adjust a very simple circuit. This has the effect of doubling the precision. In particular, by changing the taps by finding the zero point of the input voltage and by checking the shorts during tap change, by changing the taps, it is possible to prevent the circuit elements from being broken during tap change without using the winding resistance and increase the efficiency. You can.

Claims (2)

In the single winding transformer having a plurality of tabs, and the automatic voltage regulating device for stabilizing the output voltage by opening and closing each tap of the single winding transformer to the switching element under the control of the control means to add or subtract the input voltage through the step-down transformer, The step-down transformer is composed of one secondary winding and a plurality of primary windings, And a switching element connected between the plurality of primary windings and the single winding transformer to select one of the plurality of primary windings according to a control signal of the control means and to connect the single winding to the single winding transformer. . 2. The apparatus of claim 1, wherein the control means detects an output voltage and converts the voltage into a digital signal and an analog-digital converter, an open / close inspection unit for inspecting an operating state of the switching device, and driving the switching device. When the gate driver and the voltage sensing unit and the analog-digital converter detect a change in the output voltage, it is confirmed that a short does not occur between the same windings according to the output of the opening and closing inspection unit, and then the phase of the input voltage is zero. And a CPU for instructing tap-change by turning on / off the switching elements through the gate driver.