KR200207397Y1 - Automatic phase control circuit to reduce heat generation and volume of DC power supply - Google Patents

Abstract

The present invention relates to a DC power supply, and more specifically, to control the output power of a DC power supply with high efficiency by automatically controlling a phase with an SCR. It is to provide a low-cost, high-efficiency DC power supply as well as miniaturization and light weight by improving the size, high weight, low efficiency of the disadvantages of the device.

That is, SCR is phase controlled by sensing the voltage between the emitter and the collector of the output control transistor. If the reference voltage of the comparator is set to 5V, the comparator sets the difference between the emitter and collector voltage of the transistor equal to the reference voltage of 5V. By controlling the phase of the SCR to maintain it, the voltage between the emitter and collector of the transistor is always maintained at 5V.

At this time, when the input voltage is 55V, the output voltage is 1V, and the output current is 5A, the voltage between the emitter and the collector of the transistor is maintained at 5V, and when the {P = VI} formula is applied, it becomes {5V × 5A = 25W}. Therefore, the conventional DC power supply has a loss (heating amount) of 54V X 5A = 270W and the output power is 1V X 5A = 5W, whereas the DC power supply of the present invention has a calorific value loss of 5V X 5A = 25W and an output of 1V. Since X 5A = 5W, high efficiency is achieved at a small size, light weight, and low cost.

Description

Automatic phase control circuit to reduce heat and volume of DC power supply.

The present invention relates to an improvement of a DC power supply, and in particular, it significantly reduces the amount of heat generated in an output transistor, thereby reducing the capacity of the output transistor, the size of the heat sink, and greatly reducing the power loss. This reduces the cost and electrical energy of the DC power supply and makes the volume and weight smaller and lighter.

1 is a circuit diagram of a conventional (prior art) DC power supply. When the input voltage is 55V, the output voltage is 1V, and the output current is 5A, a voltage of 54V is applied between the emitter and the collector of the output transistor 1. Since the power amount of transistor 1 is calculated, about 270W of loss power is generated according to the formula of (Power P = Voltage V x Current I) (54V X 5A = 270W), and the high power is applied to the output transistor 1 by the loss power. The output transistor 1 is protected by a large heat sink and a cooling fan.

Considering the heating device here, the calorific value of 270W is very large here. That is, a large-capacity transistor capable of withstanding 270W or more of the output control transistor is required, and the size of the heat sink and the transformer for protecting the output transistor is increased, thus increasing the overall volume and power consumption of the DC power supply device and increasing the cost. There was a problem such as.

Therefore, the present invention is to automatically control the phase (Phase) by the SCR to control the output power of the DC power supply with high efficiency to solve the problems of large size, high weight, low efficiency, which is a disadvantage of the conventional DC power supply. It is an object of the present invention to provide a low-cost, high-efficiency DC power supply device in addition to miniaturization and light weight.

In order to achieve the above object, the output power is controlled by phase control of the SCR by sensing the voltage between the emitter and the collector of the output control transistor. When the reference voltage of the comparator is set to 5V, the comparator In order to maintain the collector voltage difference equal to the reference voltage of 5V, the phase of the SCR is automatically controlled so that the voltage between the emitter and the collector of the transistor is always maintained at 5V.

At this time, when the input voltage is 55V, the output voltage is 1V, and the output current is 5A, the voltage between the emitter and the collector of the transistor is maintained at 5V, and when the {P = VI} formula is applied, it becomes {5V × 5A = 25W}. Therefore, while the conventional DC power supply has a loss (heating amount) of 54V X 5A = 270W and the output power is 1V X 5A = 5W, the DC power supply of the present invention has a calorific value loss of 5V X 5A = 25W, and an output. Since 1V X 5A = 5W, high efficiency is realized at small size, light weight, and low cost.

Hereinafter, with reference to the accompanying drawings, preferred embodiments of the present invention in detail as follows.

1-a circuit diagram of a conventional DC power supply.

2-a circuit diagram of an embodiment of the present invention.

Figure 3 - is also changed according to the output voltage V _CE of the graph of a conventional DC power supply.

4-V _CE change according to the output voltage of the DC power supply of the present invention

Graph too.

5-a circuit block diagram of the present invention.

6-waveform diagram of a typical commercial AC power supply.

7-Output waveform diagram of the tap pointer TP1 of the present invention.

8-Output waveform diagram of the tap pointer TP11 of the present invention.

9-a detailed circuit diagram of an embodiment of the present invention.

10-Rectified waveform diagram by the present invention diode (D2) (D3).

Fig. 11-Output waveform diagram of the inventive tap pointer TP3.

12-Output waveform diagram of the tap pointer TP4 of the present invention.

Figure 13-Open structure of the present invention (Open-Collector) type OP-AMP (AMP) is also an internal structure diagram.

14-Output waveform diagram of the tap pointer TP6 of the present invention.

15-An enlarged waveform diagram of a time axis of the inventive tap pointer TP6.

Fig. 16-Output waveform diagram of the tap pointer TP10 in the standard state of the present invention.

Figure 17-Tap pointer (TP10) output waveform diagram when the potential is lowered in the present invention.

18-Output waveform diagram of the tap pointer TP12 in the standard state of the present invention.

Fig. 19-An output waveform diagram of the tap pointer TP12 when the output voltage is increased in the present invention.

20-Tap pointer (TP10) output waveform diagram when the load current is low in the present invention.

Figure 21-Tap pointer (TP10) output waveform diagram when the load current increases in the present invention.

22 is a circuit diagram of another embodiment of the present invention.

23 is a circuit diagram of still another embodiment of the present invention.

<Explanation of symbols for the main parts of the drawings>

(OP3)-Comparator (AC)-AC Voltage

(DC)-DC voltage (TRANS)-Transformer

(D1)-bridge diode (L1)-coil

(TP1) (TP2)-AC power input terminals (D2) to (D3)-Diode

(TP1)-(TP19)-tab pointer (T1)-trans

(TP16) (TP17)-Output terminal (TP13)-Reference voltage pointer

(U1) to (U4)-Comparators (OUT)-Output

(GND)-Ground (R1)-(R21)-Resistor

(R17)-semi fixed resistor (R20)-variable resistor

(Q1) to (Q3)-transistor (C1) to (C5)-capacitor

(PC1)-Photocoupler (SCR)-Silicon Controlled Rectifier

(BLK1)-Commutator (BLK2)-Phase Control

(BLK3)-DC Power Smoothing Part (BLK4)-DC Voltage Control Unit

(BLK5)-current detector. (BLK6)-Output Voltage Detection Comparison Unit

(BLK7)-Phase Sync and Sawtooth Generator (BLK8)-Phase Control Wave Generator

(BLK9)-phase control amount detector

(BLK10)-Reference voltage generation and output voltage setting section.

(BLOCK1)-automatic phase control

FIG. 2 is an automatic phase control circuit of the present invention for reducing the amount of heat generated by a DC power supply. In order to reduce the amount of heat generated by the transistor 2, a voltage is sensed between the emitter and the collector of the transistor 2 and phase controlled by an SCR. If the reference voltage of OP3 is set to 5V, the comparator OP3 automatically controls the phase of the SCR to maintain the difference between the emitter and collector voltage of transistor 2 equal to the reference voltage of 5V, thereby providing a voltage between the emitter and collector of transistor 2 This voltage is always maintained at 5V. At this time, when the input voltage is 55V, the output voltage is 1V, and the output current is 5A, the voltage between the emitter and the collector of transistor 2 is maintained at 5V.

Applying the formula {P = VI} above, it becomes {5V × 5A = 25W}. Therefore, in the case of the conventional DC power supply, there is a heat dissipation of 54V X 5A = 270W, and output = 1V X 5A = 5W, whereas in the case of Figure 2 there is a heat dissipation of 5V X 5A = 25W, output = 1V X 5A = 5W.

The above results are summarized in [Table 1] below.

Table 1

division Jong Rae circuit The circuit of the present invention Remarks Required load power 1V × 5A = 5W 1V × 5A = 5W Equal Power Consumption of a Transistor (Loss) 54V × 5A = 270W 5V × 5A = 25W About 11: 1 efficiency Low High The higher the better Calories Many Less Less is better Size and capacity of devices such as heat sinks and transistors greatness Small Smaller is better Size of the device Large (large) Small (small) Smaller is better Weight of the device High weight Light weight The lighter the better Cost High Low Lower is better

3 and 4 is a graph comparing the change of V _CE (voltage between emitter and collector) according to the output voltage of the conventional conventional DC power supply circuit and the present invention DC power supply circuit. As can be seen that the lower the output voltage, the greater the voltage of V _CE . On the other hand, the DC power supply circuit according to the present invention can be seen that the constant V _CE voltage is caught, regardless of the output voltage as shown in FIG.

FIG. 5 is a block diagram showing a schematic configuration of the present invention, in particular an automatic phase control unit is a key part of the present invention for improving the disadvantages of the general DC power supply mentioned above.

First, a commercial AC voltage having a waveform as shown in FIG. 6 is transformed into a voltage required by the present invention using a transformer, and then rectified into a bridge diode. The waveform is shown in FIG. It becomes a pulse.

Next, as much power (time, waveform) as needed in the phase control section is passed and converted from the smoothing circuit to a complete direct current, and the converted direct current is outputted only through the direct current control circuit. The function is the variability of direct current.

The DC comparing unit to which the reference voltage for comparison is applied constantly monitors the control value and the output value, corrects the error, and outputs the correct DC. The detecting unit detecting the phase control amount slightly increases the amount of power required by the output. The measured value is sent to the level comparison and pulse width control unit and compared with the reference waveform. The synchronized control waveform is sent to the phase control unit through the photo coupler. It is sending the bay to the smooth part. In this way, the amount of unnecessary power consumption can be reduced.

An important part here may be referred to as a feedback part (automatic phase control part) leading to a phase control amount detection part, a level comparison and pulse width control part, and a phase control part.

On the other hand, Figure 9 is a detailed circuit diagram according to an embodiment of the present invention, when the AC power of the sinusoidal wave of about 60 Hz as shown in Figure 6 applied to both ends of the power input terminal (TP1) (TP2) bridge of the rectifying unit (BLK1) A pulse of about 120 Hz is obtained through the diode D1.

The waveform at this time is shown in Figure 8, the role of the coil (L1) compensates for the virtual power (reactive power) and at the same time when the initial power supply surge current (Surge) by the smoothing capacitor in the DC smoothing unit (Surge) Current), surge voltage and noise are removed.

A similar effect can be obtained by connecting a resistor having an appropriate value instead of the coil L1. However, when the coil is used, the voltage drop across both ends of the coil has only a winding resistance component, which is much smaller than that of the resistor. The loss is small but bulky. For this reason, it is desirable to use coils for circuits that require large output currents or require high stability.

On the other hand, in the phase synchronization and sawtooth wave generating unit BLK7, the pulses of 120 kHz in phase with the pulses generated in the tap pointer TP11 through the diode D1 are synchronized with the diodes D2 and D3. A waveform such as 10 is generated, and the waveform and voltage across the tap pointer TP3 are determined by the voltage divider resistors R13 and R18 (V _TP3 = V (R18 / (R13 + R18))). The waveform and phase at this time are the same as those applied to the cathode of the diode D2 with only the difference in amplitude (voltage).

The voltage of the tap pointer TP4 (V _TP4 = VCC (R19 (R14 + R19))) is also taken as shown in FIG. 12. The primary role of the comparator (U4) is to function as a comparator.In the case of the OP-AMP, when configured with the phase synchronizer and the sawtooth generator BLK7, the output follows the polarity of the input by comparing the polarity of the input. .

In other words, if the input has a forward polarity, the output will have a positive maximum output, and if the reverse polarity has a positive output, the output will have a negative maximum.

In detail, the voltage level of the tap pointer TP3 is compared based on the reference point of the tap pointer TP4, and the comparator (High is higher than the reference potential, and low if it is lower than the reference potential). The output of U4) is switched.

That is, it has only two output states. It should be noted that the comparator U4 is an open-collector type, and as shown in FIG. 13, a collector of a transistor is connected to the end of the internal output, so that the output is positive. If the output is electrically open, and the output becomes negative, the output OUT approaches the ground potential by flowing current through the collector and emitter.

In this case, a pull-up resistor R21 is connected to the output OUT of the comparator U4 in order to use the positive output. The potential of the tap pointer TP4 is compared by comparing the inputs of both ends of the comparator U4. If the potential of the tap pointer TP3 is increased, the output OUT is opened, and thus the V _CC voltage is charged to the capacitor C5 through the pull-up resistors R21 and R16.

The waveform of the tap pointer TP3 is a pulse wave that rectifies the sinusoidal wave and has a constant period and duty cycle. The tap pointer TP4 is repeatedly raised and lowered from the tap pointer TP4. When it is lower than TP3), the output of the comparator U4 changes to the ground GND potential, and at this time, the charge charged in the capacitor C5 is discharged only through the resistor R16.

As a result, the potential of the tap pointer TP6 is made through the resistor R21 + resistor R16 during charging and the discharge is made only through the resistor R16. Therefore, the charging time = C5 (R21 + R16)> discharge time = C21 × R16 always results in longer charging time than discharging time.

Therefore, by appropriately adjusting the ratio of the pull-up resistor R21 and the output resistor R16 in this portion, a desired sawtooth wave in the form as shown in Fig. 14 can be obtained.

On the other hand, the reference voltage generation and output voltage setting unit BLK10 is preferably designed by using elements and circuits that require extraordinary degree of accuracy in order to have a minimum error as a reference for all comparisons. It is also necessary to arrange.

If the reference voltage is wrong here, the rest of the DC output value will always be output with error, and if the reference voltage changes with time, the DC output will also change with time.

The reference voltage output from the tap pointer TP13 is always constant, and the divided voltage is connected to the inverting terminal of the comparator U1 through the variable resistor R20 for setting the output voltage to the inverting terminal (-) of the comparator U1. The input voltage is capable of adjusting the voltage from the minimum 0V to the maximum reference voltage according to the variable value of the variable resistor R20. If you want to adjust the voltage more finely, you can use a variable resistor that can be rotated several times, such as a potentiometer (potentiometer).

The tap pointer TP14 of the output voltage detection comparator BLK6 monitors the DC voltage of the output terminals TP16 and TP17 through the resistors R1 and R3 and always generates a constant voltage at the reference voltage generator. In TP13, the correction value for the error generated in comparison with the voltage set through the variable resistor R20 is output through the comparator U1, where the voltage of the correction is the tap pointer TP15 voltage. In an ideal circuit, the value of the tap pointer TP15 remains constant with little change.

The DC voltage controller BLK4, which directly controls the DC output voltage, controls the base current of the transistor Q3 through the base resistor R11 of the transistor Q3 by a voltage equal to the error correction amount from the tap pointer TP15. In addition, the transistor Q1 is controlled through the resistor R12, the transistor Q2, the resistor R6, and the like, so that the voltage between the emitter and the collector of the transistor Q1, that is, the tap pointer TP19 and the tap pointer TP18. To control the voltage difference.

Here, the resistor R4 uses a low value resistor as a resistor for protecting the transistor Q1 from the emitter current of the rapidly rising transistor Q1. Transistor Q1 should be set by calculating the total current, the voltage between the emitter collector to the maximum, and the maximum amount of power to be applied, followed by sufficient heat dissipation design. The majority of frequent failures due to improper circuit design occur here.

In the case of a DC power supply that requires a large current, a plurality of DC voltage controllers BLK4 may be connected in parallel. In general, DC power supplies rectify the required DC power supply voltage in consideration of the maximum voltage and loss to be output through the rectifier circuit. Voltage is applied.

This means that if you use an output of 1V / 5A for a power supply rated at 55V rectified voltage (DC input voltage) and a maximum output of 50V / 5A, the power that the output transistors will bear is: voltage 55V-1V = 54V, current = 5A, power = 54 x 5 = 270W power consumption.

Considering the heating device, the heat output of 270W is very large here. Therefore, the output control transistor needs a capacity that can withstand more than 270W, and the size of the heat sink and transformer required for heat dissipation increases, thus increasing the overall volume and increasing the cost.

However, if the circuit of the present invention is controlled by the phase control unit BLK2, the voltage of the tap pointer TP12 is always kept slightly above the minimum value of the required power and the voltage, so the maximum of both ends of the transistor Q1 is maintained. It does not take more than 5V.

The power at this time is calculated as above, resulting in voltage 5V, current = 5A, and power = 5 X 5 = 25W. Compared with the existing circuit, the power consumption is only about 1/11. Since the heat generation amount is small, the design of the heat dissipation can be reduced, and the size of the DC power supply can be reduced because the output control transistor can withstand only 25W. .

That is, compared with the conventional method, the advantage is that the size of the output transistor does not need to be large, so that the overall size is smaller, the size of the heat sink is significantly smaller, and the output transistor is also smaller, which reduces cost and power consumption. It can greatly reduce the volume and weight of the device.

If the variable resistor R20 is adjusted to increase the output voltage, the voltage of the tap pointer TP15 is lowered through the output voltage detection comparator BLK6, which is between the emitter TP19 and the collector TP18 of the transistor Q1. Will step down the voltage. Stepping down the voltage at both ends here lowers the potential of the tap pointer TP16, and the output voltage increases because the potential difference between the tap pointer TP17 and the tap pointer TP16 is widened.

The conventional DC power supply circuit adjusts the voltage by this operation. However, the DC power supply circuit of the present invention receives the voltage lowered between both ends of the transistor Q1 through the non-inverting terminal of the comparator U2 in addition to the above-described primary operation, and the negative tap pointer TP19 and the both ends of Q1 of the rectifier. Compared to the voltage), the correction is output to the tap pointer TP9.

At this time, the potential of the tap pointer TP9 is lowered as usual, which is input to the non-inverting terminal of the comparator U3 located in the phase control wave generator BLK8 through the resistor R15. The role of the resistor R17 is used to adjust the pulse width for supplying the minimum required power in the normal state.

Meanwhile, the sawtooth wave of FIG. 14 described above is always constantly input to the inverting terminal of the comparator U3. The output width of the tap pointer TP10 is determined by the potential applied to the non-inverting terminal of the comparator U3. In other words, when the potential of the tap pointer TP9 is lowered, the pulse width of the tap pointer TP10 becomes wider (negative logic).

In this case, the pulse width means ON-time of phase control. FIG. 16 shows the state of the tap pointer TP10 in the standard state, and FIG. 17 shows the change of the tap pointer TP10 when the potential of the tap pointer TP9 is lowered. The waveform of the tap pointer TP10 thus made is transmitted to the SCR1 through the photocoupler PC1. The purpose of the photocoupler PC1 is to electrically insulate.

In SCR1, the same voltage as that of the tap pointer TP11 is turned on as much as the waveform of the tap pointer TP10 and transferred to the tap pointer TP12. At this time, the pulse wave waveform is directly smoothed capacitors C1, C2, and ( Is converted to direct current through C3).

Looking back, since the ON time of the SCR (silicon controlled rectifier) is wider than usual, the potential of the tap pointer TP12 is increased as shown in FIG. 18 to 19, and the potential of the tap pointer TP17 is increased. Is raised. This is immediately transferred to the tap pointer TP14 for monitoring the output voltage. Since the potential of the output tap pointer TP15 of the comparator U1 becomes high again, the voltage difference between both ends of the transistor Q1 becomes large, and between both ends of the transistor Q1. The voltage difference is always kept constant.

At this time, the potential of the tap pointer TP16 is increased so that the DC output always obtains the required constant voltage. Such operations are performed simultaneously.

If a constant voltage is output but the load increases and the current rises, the above operations are performed. The voltage of the tap pointer TP12 remains constant and the pulse width (ON-time) of the tap pointer TP10 is constant. By expanding from 20 to 21 as shown in FIG. 21, the output current and power are increased and the required constant voltage is maintained.

In FIG. 9, the automatic phase controller BLOCK1 is a core part of the present invention, and includes a DC voltage controller BLK4, a phase control amount detector BLK9, a phase control wave generator BLK8, a phase controller BLK2, and a DC power smoother. It is composed of (BLK3).

22 and 23 show examples of circuits in which the phase control unit BLK2 can be configured by changing elements (changing) elements, changing element positions, and the like among the components of the automatic phase control unit BLOCK1.

That is, FIG. 22 achieves the present invention by connecting a triac capable of controlling the phase of alternating current instead of SCR1 to the front end of the bridge diode D1 to control the phase, and also as shown in FIG. 23. The present invention may be achieved by omitting (D1) and controlling the phase while directly rectifying using SCR.

The current detector BLK5 may be used as a device that monitors the current by using the detected current and protects the circuit by overcurrent and informs the outside, or a default value of the constant current control.

The resistance (R5) used here is advantageous because a high voltage can be used to obtain a high voltage, but the heat generation amount increases, so the capacity of the resistance increases and the error due to the Temperature Coefficient of Resistance increases. There is such a problem. Therefore, use a shunt resistor of manganese series (Manganin-manganine) with a low resistance of about 0.1 mA.

The gain obtained by using the resistor is advantageous in that the resistance temperature coefficient is good, the thermal power is small, the resistance value is small, and the heat generation amount and the capacity of the resistance can be reduced, and the linearity is good due to the excellent resistance characteristics. There is a point.

The value of the current obtained above is obtained as voltage as follows. If the resistance of 0.1Ω is used as V _shunt = I x R5, 1x0.1 = 0.1V at 1A and 2X0.1 = 0.2V at 2A. have. These values are so low that they cannot be used immediately, but are used after amplification through OP-AMP.

As described above, the present invention always maintains the proper power to obtain the required constant voltage, and dramatically reduces the amount of heat generated from the output transistor, thereby reducing the capacity of the output transistor, the size of the heat sink, and reducing the power loss. It is a very useful design that has the effect of reducing the cost of DC power supply device and making the volume and weight smaller and lighter.

Claims (4)

A DC power supply that transforms a commercial AC voltage, rectifies, smoothes, and controls it to output a desired voltage (power). A DC power supply is formed through a rectifying circuit to form a voltage between the emitter and the collector of the output TR. It is configured to detect and feed back to the phase control unit, and converts the smoothed circuit into direct current by passing as much power (time, waveform) as necessary in the phase control part, and the converted direct current is again passed through the voltage control circuit. The output voltage comparator compares the constant control value with the output value, corrects the error, and outputs the correct voltage.The detector (detecting the output TR emitter-collector) that detects the phase control amount is required at the output. Compares the level slightly higher than the voltage value to the Pulse Width control unit and sends it to the Pulse Width control unit. Automatic phase control circuit to reduce the heat and volume of the DC power supply, characterized in that the type is sent to the phase control unit through a photo coupler to always send only the optimal amount of power to the smoothing unit. 2. The automatic phase control circuit of claim 1, wherein the phase control unit made of triac instead of SCR1 is connected to the front end of the rectifying unit to control the phase of the DC power supply. 2. The automatic phase control according to claim 1, wherein the bridge diode D1 of the rectifier BLK1 is omitted and the phase is controlled while directly rectifying using SCR. Circuit. The apparatus of claim 1, wherein the automatic phase controller is insulated from the phase controller, the smoother, the DC controller, the detector, the level comparator, the pulse width controller, the phase controller, the level comparator, and the pulse width controller. Automatic phase control circuit to reduce heat generation and volume of the configured DC power supply.