CN208539799U - A kind of AC conversion circuit based on experiment instruments used for education - Google Patents

Abstract

The utility model discloses a kind of AC conversion circuits based on experiment instruments used for education, including 12V Off-line SMPS circuit, voltage regulator circuit and output voltage regulation circuit, the voltage regulator circuit is electrically connected with 12V Off-line SMPS circuit, and output voltage regulation circuit is electrically connected with voltage regulator circuit.It should be based on the AC conversion circuit of experiment instruments used for education, chip U1 selects DK124 in 12V Off-line SMPS circuit, at low cost, generates heat low without cooling fin, circuit element is few, volume is also small, replaces linear voltage stabilization route using DC-DC lowering and stabilizing blood pressure chip AOZ1014 pressure stabilizing route, delivery efficiency is high, it can reach 80%~90%, energy-saving effect is good, generates heat low, does not have to radiator；It adjusts output voltage by slide rheostat R23 continuously to export between 1.5V~9V, any voltage value in 1.5V~9V is all available；Overall output is high-efficient, and energy-saving effect is good, and cabinet volume reduces, and cost reduces, and any voltage value in 1.5V~9V can be obtained.

Description

A kind of AC conversion circuit based on experiment instruments used for education

Technical field

The utility model relates to test to use technical field of electronic equipment, specially a kind of friendship based on experiment instruments used for education Galvanic electricity conversion circuit.

Background technique

Primary school, junior middle school student's power supply are that the AC conversion of 220V is done Experiments of Electricity for student for low pressure direct current of voltage regulation With instruments used for education, mono- grade of point of 6 grades of output of the every 1.5V of 1.5V~9V, rated current 1.5A.Product is all using this technology at present: 220V exchange is exchanged into 15V through transformer pressure-reducing, rectified filtering obtains low-voltage direct, and linear voltage regulator circuit pressure stabilizing is defeated Stable low-voltage direct, output voltage are adjusted with band switch out.

Current student power source has following problems and disadvantages:

1, delivery efficiency is low, and delivery efficiency can only achieve 10%~40%；

2, fever is serious, and pressure stabilizing adjusts the pipe cooling fin to be increased；

3, the volume of cabinet is big；

4, due to using transformer, product weight weight；

5, output voltage can only be this six fixed voltage values of 1.5V, 3V, 4.5V, 6V, 7.5V, 9V, experiment to 2V, 4V does not just have, and student experimenting is inconvenient；

In view of the above-mentioned problems, therefore proposing a kind of AC conversion circuit based on experiment instruments used for education.

Utility model content

The purpose of this utility model is to provide a kind of AC conversion circuits based on experiment instruments used for education, have defeated The advantages of high-efficient out, operating temperature is low, small in size, any voltage value between exportable 1.5V~9V, solves existing skill The problem of delivery efficiency is low in art, and fever is serious, and cabinet volume is big, fixed value that there are six output voltages.

To achieve the above object, the utility model provides the following technical solutions: a kind of friendship based on experiment instruments used for education Galvanic electricity conversion circuit, including 12V Off-line SMPS circuit, voltage regulator circuit and output voltage regulation circuit, the pressure stabilizing electricity Road is electrically connected with 12V Off-line SMPS circuit, and output voltage regulation circuit is electrically connected with voltage regulator circuit；

The 12V Off-line SMPS circuit includes bridge rectifier diode DB1, chip U1, transformer T1 and photoelectricity The model DK124 of coupler U2, chip U1；The model PC817C of photoelectrical coupler U2；The model of chip U3 AOZ1014；The foot 1 and foot 3 of bridge rectifier diode DB1 connect the output end of inductance L1, and the input of inductance L1 terminates 220V power supply Input terminal；The foot 2 of the bridge rectifier diode DB1 connects the foot 1 of transformer T1, the foot 1 and foot 2 and photoelectricity coupling of chip U1 The foot 3 of clutch U2 connects the foot 4 of bridge rectifier diode DB1, and the foot 3 of chip U1 connects the foot 3 of photoelectrical coupler U2, chip U1's Foot 4 connects capacitor C3 ground connection, and the foot 4 of photoelectrical coupler U2 connects the input terminal of capacitor C3, and the foot 5- foot 8 of chip U1 meets transformer T1 Foot 2, the foot 2 of transformer T1 meets the foot 2 that diode D1 resistance R1 and capacitor C4 meet bridge rectifier diode DB1, transformer T1 Foot 3 meet diode D2 and connect+12V power output end, the foot 4 of transformer T1 is grounded；The foot 1 of the photoelectrical coupler U2 connects electricity Resistance R7 connects the output end of diode D2, and 2 series resistor R9 of foot, capacitor C9 and the resistance R5 of photoelectrical coupler U2 meets diode D2 Output end, between the input terminal of resistance R7 and the input terminal of resistance R9 and connecting resistance R8, the output terminating resistor R6 of capacitor C9 is connect Ground；

The voltage regulator circuit includes chip U3, and+12V the power supply that the foot 1 of chip U3 connects 12V Off-line SMPS circuit is defeated Terminal out, 1 series resistor R12 of foot, resistance R14, Light-emitting diode LED 1, capacitor C13 and the resistance R19 of chip U3 meet chip U3 Foot 5, the input terminal of the 3 connecting resistance R13 connecting resistance R12 of foot 2 and foot of chip U3, the both ends shunt-wound capacitance C11 of resistance R13, electricity The input terminating resistor R17 of resistance R14 connects the foot 6 of chip U3, the input terminal order of capacitor C13 to controllable silicon SCR, resistance R15 and The input terminal of switch K1 connecting resistance R14, the input terminating resistor R16 of resistance R15 connect the input terminal of capacitor C13, and the two of resistance R16 Hold the both ends of shunt-wound capacitance C12, capacitor C13 and resistance R19 and connecting resistance R18, the output end ground connection of Light-emitting diode LED 1；

The output voltage regulation circuit includes slide rheostat R23, resistance R21 and digital display voltmeter, the foot 8 of chip U3 It meets inductance L2 and inductance L3 and connects power output terminal, the 4 connecting resistance R21 of foot of chip U3 connects the output end of digital display voltmeter, resistance The input termination slide rheostat R23 of R21 connects the output end of inductance L2, and the foot 7 of chip U3 meets diode D3 and connects digital display transformer Output end, the both ends of diode D3 and connecting resistance R20 and capacitor C14；The both ends shunt-wound capacitance C15 of the digital display transformer, The both ends of capacitor C15 and connecting resistance R22.

Preferably, the chip U3 is depressured chip, working frequency 500KHz, maximum output using AOZ1014DC-DC Electric current is 5A.

Preferably, the output end of the power output terminal of the output termination of the inductance L3 is pressed between 1.5V~9V.

Preferably, the one-way SCR A electrode potential is 8V, the angle chip EN current potential 4V, when the electric current for flowing through L2 exists When 1.575~2.25A, dry reed tube closure, controlled silicon conducting, for A electrode potential less than 0.6V, EN current potential is less than 0.3V, and MOSFET is cut Only, have the function that output overcurrent and short-circuit protection.

Compared with prior art, the beneficial effects of the utility model are as follows:

It should be based on the AC conversion circuit of experiment instruments used for education, using 12V Off-line SMPS circuitry instead Transformer and current rectifying and wave filtering circuit in traditional product provide 12V direct voltage of voltage regulation, and wherein chip U1 selects DK124, at This is low, generates heat low without cooling fin, circuit element is few, and volume is also small, using DC-DC lowering and stabilizing blood pressure chip AOZ1014 pressure stabilizing line Road replaces linear voltage stabilization route, and delivery efficiency is high, can reach 80%~90%, and energy-saving effect is good, generates heat low, does not have to radiator； Output voltage is adjusted by slide rheostat R23 continuously to export between 1.5V~9V, and is shown with digital display voltmeter, Any voltage value in 1.5V~9V is all available；Overall output is high-efficient, and energy-saving effect is good, and cabinet volume reduces, cost drop It is low, any voltage value in 1.5V~9V can be obtained.

Detailed description of the invention

Fig. 1 is the 12V Off-line SMPS circuit diagram of the utility model；

Fig. 2 is the voltage regulator circuit and output voltage regulation circuit connection figure of the utility model.

In figure: 1,12V Off-line SMPS circuit；2, voltage regulator circuit；3, output voltage regulation circuit.

Specific embodiment

The following will be combined with the drawings in the embodiments of the present invention, carries out the technical scheme in the embodiment of the utility model Clearly and completely describe, it is clear that the described embodiments are only a part of the embodiments of the utility model, rather than whole Embodiment.Based on the embodiments of the present invention, those of ordinary skill in the art are without making creative work Every other embodiment obtained, fall within the protection scope of the utility model.

A kind of AC conversion circuit based on experiment instruments used for education referring to FIG. 1-2, including 12V off-line type switch Power circuit 1, voltage regulator circuit 2 and output voltage regulation circuit 3, voltage regulator circuit 2 and 12V Off-line SMPS circuit 1 are electrically connected It connects, output voltage regulation circuit 3 is electrically connected with voltage regulator circuit 2；12V Off-line SMPS circuit 1 includes two pole of bridge rectifier Pipe DB1, chip U1, transformer T1 and photoelectrical coupler U2, the model DK124 of chip U1；The model of photoelectrical coupler U2 PC817C；The model AOZ1014 of chip U3；The foot 1 and foot 3 of bridge rectifier diode DB1 connect the output end of inductance L1, electricity The input for feeling L1 terminates 220V power input terminal；The foot 2 of bridge rectifier diode DB1 connects the foot 1 of transformer T1, chip U1's The foot 3 of foot 1 and foot 2 and photoelectrical coupler U2 connects the foot 4 of bridge rectifier diode DB1, and the foot 3 of chip U1 connects photoelectric coupling The foot 3 of device U2, the foot 4 of chip U1 connect capacitor C3 ground connection, and the foot 4 of photoelectrical coupler U2 connects the input terminal of capacitor C3, chip U1's Foot 5- foot 8 connects the foot 2 of transformer T1, and the foot 2 of transformer T1 meets diode D1 resistance R1 and capacitor C4 and connects bridge rectifier diode The foot 2 of DB1, the foot 3 of transformer T1 meet diode D2 and connect+12V power output end, and the foot 4 of transformer T1 is grounded；Photoelectric coupling The 1 connecting resistance R7 of foot of device U2 connects the output end of diode D2,2 series resistor R9 of foot, capacitor C9 and the resistance of photoelectrical coupler U2 R5 connects the output end of diode D2, between the input terminal of resistance R7 and the input terminal of resistance R9 and connecting resistance R8, the output of capacitor C9 Terminating resistor R6 ground connection；Voltage regulator circuit 2 includes chip U3, and chip U3 is depressured chip using AOZ1014DC-DC, and working frequency is The foot 1 of 500KHz, maximum output current 5A, chip U3 connect the+12V power output end of 12V Off-line SMPS circuit Son, 1 series resistor R12 of foot, resistance R14, Light-emitting diode LED 1, capacitor C13 and the resistance R19 of chip U3 connect chip U3's Foot 5, the input terminal of the 3 connecting resistance R13 connecting resistance R12 of foot 2 and foot of chip U3, the both ends shunt-wound capacitance C11 of resistance R13, resistance The input terminating resistor R17 of R14 connects the foot 6 of chip U3, and the input terminal order of capacitor C13 to controllable silicon SCR, resistance R15 and is opened The input terminal of K1 connecting resistance R14 is closed, wherein the conducting voltage of unidirectional controllable silicon S CR is 2V, blanking voltage 0.6V, resistance The input terminating resistor R16 of R15 connects the input terminal of capacitor C13, the both ends shunt-wound capacitance C12 of resistance R16, capacitor C13 and resistance Simultaneously connecting resistance R18, the output end of Light-emitting diode LED 1 are grounded at the both ends of R19；Output voltage regulation circuit 3 includes sliding variable resistance Device R23, resistance R21 and digital display voltmeter, the foot 8 of chip U3 meets inductance L2 and inductance L3 connects power output terminal, power supply output The output end of terminal is pressed between 1.5V~9V, and the 4 connecting resistance R21 of foot of chip U3 connects the output end of digital display voltmeter, resistance The input termination slide rheostat R23 of R21 connects the output end of inductance L2, and the foot 7 of chip U3 meets diode D3 and connects digital display transformation The output end of device, the both ends of diode D3 and connecting resistance R20 and capacitor C14；The both ends shunt-wound capacitance C15 of digital display transformer, electricity Hold the both ends of C15 and connecting resistance R22.

The AC conversion circuit based on experiment instruments used for education, inductance L1, diode DB1 and capacitor C1 form bridge Formula rectification circuit, filtering obtain 314V DC voltage, are switched to the high pressure of 314V by chip U1, that is, DK124 and transformer T1 The low-voltage DC of 12V, process are as follows:

1, upper end starts

When electrifying startup, chip U1 is by the internal high-voltage current source for connecting OC and VCC pin, to external VCC energy storage Capacitor charging closes high-voltage current source when VCC voltage is increased to 5V, and start-up course terminates, and control logic starts to export PWM Pulse；

2, soft start

After electrifying startup, chip U1 starts to export pwm pulse, to prevent instantaneous output voltage from overshooting, transformer T1 magnetic Core saturation, power tube and secondary commutation pipe stress are excessive, and 16mS soft starting circuit built in chip U1 can be stepped up in 16mS The service time of PWM makes the peak point current of power tube increase linearly to peak inrush current from 100mA；

3, feedback control

Chip U1 uses the PWM control mode of Cycle by Cycle limit value peak point current, is adjusted by detecting the feedback voltage of FB Electric current is limited, after PWM is opened, chip U1 detects power tube and exports electric current, until power tube output electric current reaches current limit Switch-off power pipe after electric current processed, waits next PWM to open the period；The linear adjusting limit of FB voltage meeting between 1.5V-2.5V Electric current processed, the corresponding maximum limitation electric current of 1.5V, the corresponding minimum limitation electric current of 2.5V, when load down, FB voltage can gradually drop It is low；On the contrary then FB voltage can gradually rise, and work as overload, and when FB voltage is less than 1.5V, chip U1 can enter short circuit or mistake Carry the judgement of protection；Very light when loading, when FB voltage is greater than 2.5V, the switching frequency of PWM can be reduced to by chip U1 by 65KHz 22KHz, and it is open-minded with minimum service time, and when loading lighter, FB voltage will continue to increase；When FB voltage is higher than 2.8V, Chip U1 stops PWM output, and chip U1 enters standby burst mode.

4, standby burst mode

When standby, FB voltage can be increased to 2.8V or more, and chip U1 stops PWM output, when output voltage slightly declines, FB When voltage is lower than 2.8V, chip U1 can export some pwm pulses again to maintain the output voltage of setting；The output of this burst Lower stand-by power consumption may be implemented in mode.

5, frequency modulation(PFM)

In order to meet the design requirement of EMI, the design complexities and cost of EMI are reduced, are equipped with a frequency in chip U1 The frequency of modulation circuit, PWM will be run on 16 Frequency points centered on 65KHz with the step frequency of 0.5KHz.

6, self-powered

Chip U1 has used confession power technology, controls the voltage of VCC in 5V or so, the electric current for providing chip U1 itself disappears Consumption omits outside transformation auxiliary winding, simplifies design.

7, peak point current is protected

When whenever chip U1 detects that the peak point current of internal power pipe is more than 1.3A, power tube is immediately turned off, is protected Power tube and corresponding device are protected from destroying.

8, firm power controls

Export overpower when high pressure in order to prevent, the built-in high-low pressure power compensating circuit of chip U1 makes different power grids electricity Peak power output when pressure input is almost the same.

9, abnormity of power supply

When leading to VCC voltage lower than 3.6V because of external exception, chip U1 is restarted switch-off power pipe, because outer When portion causes VCC voltage to be higher than 6.5V extremely, start VCC overvoltage protection immediately, stops output pulse, until VCC overpressure conditions It releases.

10, power tube overvoltage protection

Secondary open circuit, inlet highway overtension, transformer T1 leakage inductance is excessive, can all cause the higher point of power tube OC Peak voltage；To protect power tube not to be destroyed, when circuit detects that power tube OC voltage is more than 600V, FB can be drawn high immediately Voltage stops output pwm pulse, until power tube overpressure conditions release.

11, short circuit and overload protection

When secondary output short-circuit or overload, FB voltage can be lower than 1.3V；In some applications, since the perception such as motor is negative Load needs higher starting current on startup, may cause the overload of circuit short time, therefore chip U1 for the first time protect by overload The judgement time of shield is 512mS, if FB voltage restores normally in 512mS, chip U1 will not determine overload or short circuit；If FB voltage is consistently lower than 1.3V in 512mS, then is determined as secondary output short-circuit, starts short-circuit protection immediately, and short circuit is protected Shield determines that the time shorten to 32mS, until short-circuit state releases.

12, overheat protector

Whenever detect that chip temperature is more than 130 DEG C, start overheat protector immediately, stops output pulse, until mistake Warm situation releases.

Pressure stabilizing process: output is connected to FB pin, feedback voltage V FB and the comparison voltage set by feed circuit Vcomp relatively after, generate mistake voltage signal, mistake voltage signal is input to PWM module, and PWM is according to the size of mistake voltage Duty ratio is adjusted, to achieve the purpose that control output voltage, the effect of oscillator is the triangular wave for generating PWM working frequency, Triangular wave generates square wave after chopping voltage copped wave, and square wave is exactly to control the turn-on time of MOSFET to control output Voltage and reach pressure stabilizing purpose.

Output voltage: adjusting slide rheostat R23, changes the size of VFB, realizes that output voltage 0.8V~9V continuously may be used It adjusts, and is shown by digital display voltmeter.

Circuit protection: when EN voltage is greater than 2V, MOSFET conducting, when EN voltage is less than 0.6V, MOSFET cut-off, When flowing through the electric current of L3 in 1.575~2.25A, dry reed tube conducting, controlled silicon conducting, EN current potential is less than 0.6V, and MOSFET is cut Only, have the function that output overcurrent and short-circuit protection, chip have thermal-shutdown circuit by oneself.

The AC conversion circuit based on experiment instruments used for education is replaced using 12V Off-line SMPS circuit 1 Transformer and current rectifying and wave filtering circuit in traditional product provide 12V direct voltage of voltage regulation, and chip U1 is selected to select DK124, cost It is low, it generates heat low without cooling fin, circuit element is few, and volume is also small, using DC-DC lowering and stabilizing blood pressure chip AOZ1014 pressure stabilizing route Instead of linear voltage stabilization route, delivery efficiency is high, can reach 80%~90%, and energy-saving effect is good, generates heat low, does not have to radiator；It is logical The output voltage adjusting circuit of slide rheostat R23, resistance R21 and digital display voltmeter composition is crossed to adjust the electricity of display output Pressure, slide rheostat R23 adjustable output voltage continuously export between 1.5V~9V, and any voltage value in 1.5V~9V is all It is available.

In summary: should be based on the AC conversion circuit of experiment instruments used for education, using 12V Off-line SMPS Circuit 1 replaces transformer and current rectifying and wave filtering circuit in traditional product to provide 12V direct voltage of voltage regulation, passes through slide rheostat R23 adjusts output voltage and continuously exports between 1.5V~9V, and is shown with digital display voltmeter, any in 1.5V~9V Voltage value is all available；Overall output is high-efficient, and energy-saving effect is good, and cabinet volume reduces, and cost reduces, and 1.5V~9V can be obtained Interior any voltage value.

While there has been shown and described that the embodiments of the present invention, for the ordinary skill in the art, It is understood that these embodiments can be carried out with a variety of variations in the case where not departing from the principles of the present invention and spirit, repaired Change, replacement and variant, the scope of the utility model is defined by the appended claims and the equivalents thereof.

Claims (3)

1. a kind of AC conversion circuit based on experiment instruments used for education, including it is 12V Off-line SMPS circuit (1), steady Volt circuit (2) and output voltage regulation circuit (3), it is characterised in that: the voltage regulator circuit (2) and 12V Off-line SMPS Circuit (1) electrical connection, output voltage regulation circuit (3) are electrically connected with voltage regulator circuit (2)；

The 12V Off-line SMPS circuit (1) includes bridge rectifier diode DB1, chip U1, transformer T1 and photoelectricity coupling The model DK124 of clutch U2, chip U1；The model PC817C of photoelectrical coupler U2；The model AOZ1014 of chip U3； The foot 1 and foot 3 of bridge rectifier diode DB1 connect the output end of inductance L1, and the input of inductance L1 terminates 220V power input terminal； The foot 2 of the bridge rectifier diode DB1 connects the foot 1 of transformer T1, the foot 1 and foot 2 of chip U1 and photoelectrical coupler U2's Foot 3 connects the foot 4 of bridge rectifier diode DB1, and the foot 3 of chip U1 connects the foot 3 of photoelectrical coupler U2, and the foot 4 of chip U1 connects capacitor C3 ground connection, the foot 4 of photoelectrical coupler U2 connect the input terminal of capacitor C3, and the foot 5- foot 8 of chip U1 connects the foot 2 of transformer T1, transformation The foot 2 of device T1 connects the foot 2 that diode D1 resistance R1 and capacitor C4 meet bridge rectifier diode DB1, and the foot 3 of transformer T1 connects two poles Pipe D2 connects+12V power output end, and the foot 4 of transformer T1 is grounded；The 1 connecting resistance R7 of foot of the photoelectrical coupler U2 connects diode The output end of D2,2 series resistor R9 of foot, capacitor C9 and the resistance R5 of photoelectrical coupler U2 connect the output end of diode D2, resistance Between the input terminal of R7 and the input terminal of resistance R9 and the output terminating resistor R6 of connecting resistance R8, capacitor C9 are grounded；

The voltage regulator circuit (2) includes chip U3, and+12V the power supply that the foot 1 of chip U3 connects 12V Off-line SMPS circuit is defeated Terminal out, 1 series resistor R12 of foot, resistance R14, Light-emitting diode LED 1, capacitor C13 and the resistance R19 of chip U3 meet chip U3 Foot 5, the input terminal of the 3 connecting resistance R13 connecting resistance R12 of foot 2 and foot of chip U3, the both ends shunt-wound capacitance C11 of resistance R13, electricity The input terminating resistor R17 of resistance R14 connects the foot 6 of chip U3, the input terminal order of capacitor C13 to controllable silicon SCR, resistance R15 and The input terminal of switch K1 connecting resistance R14, the input terminating resistor R16 of resistance R15 connect the input terminal of capacitor C13, and the two of resistance R16 Hold the both ends of shunt-wound capacitance C12, capacitor C13 and resistance R19 and connecting resistance R18, the output end ground connection of Light-emitting diode LED 1；

The output voltage regulation circuit (3) includes slide rheostat R23, resistance R21 and digital display voltmeter, the foot 8 of chip U3 It meets inductance L2 and inductance L3 and connects power output terminal, the 4 connecting resistance R21 of foot of chip U3 connects the output end of digital display voltmeter, resistance The input termination slide rheostat R23 of R21 connects the output end of inductance L2, and the foot 7 of chip U3 meets diode D3 and connects digital display transformer Output end, the both ends of diode D3 and connecting resistance R20 and capacitor C14；The both ends shunt-wound capacitance C15 of the digital display transformer, The both ends of capacitor C15 and connecting resistance R22.

2. a kind of AC conversion circuit based on experiment instruments used for education according to claim 1, it is characterised in that: institute It states chip U3 and chip, working frequency 500KHz, maximum output current 5A is depressured using AOZ1014DC-DC.

3. a kind of AC conversion circuit based on experiment instruments used for education according to claim 1, it is characterised in that: institute The output end for stating the power output terminal of the output termination of inductance L3 is pressed between 1.5V~9V.