CN217902332U - Timing constant current circuit - Google Patents
Timing constant current circuit Download PDFInfo
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- CN217902332U CN217902332U CN202222299378.9U CN202222299378U CN217902332U CN 217902332 U CN217902332 U CN 217902332U CN 202222299378 U CN202222299378 U CN 202222299378U CN 217902332 U CN217902332 U CN 217902332U
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- transformer
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- power supply
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02B—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
- Y02B20/00—Energy efficient lighting technologies, e.g. halogen lamps or gas discharge lamps
- Y02B20/40—Control techniques providing energy savings, e.g. smart controller or presence detection
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Abstract
The utility model discloses a timing constant current circuit, the transformer passes through triode Q1 and is connected with the PWM generator, be connected with opto-coupler PC1B on the PWM generator, parallel connection has electric capacity C2 on the output of transformer, parallel connection has electric capacity C3 on the electric capacity C2, be connected with constant current ring module on the zero line on the transformer output end, OP1A is put including fortune to the constant current ring module, diode D2, resistance R3, R4, R7, resistance R7 is established ties with transformer output's zero line, be connected with the constant voltage ring module on the live wire on the transformer output end, constant voltage ring module includes resistance R6 and R8, OP1B is put to fortune, diode D3, OP 1B's No. 6 pins that OP 6B was put to fortune pass through resistance R6 and are connected with the live wire. The utility model has the advantages that: the power supply can overcome the defect that the common constant voltage power supply cannot be started when meeting overlarge capacitive or inductive load, and can also overcome the defect that the temperature of elements of the common power supply with the overload or short-circuit constant current function is overhigh when the power supply is short-circuited and constant current.
Description
Technical Field
The utility model relates to the technical field of circuits, specifically indicate a timing constant current circuit.
Background
The existing switch power supply products can be divided into single constant voltage power supplies according to the output types; a single constant current power supply; and a power supply of constant voltage and constant current at the same time. The most widely used power supply in the market has a single constant voltage function, the power supply can realize constant output voltage in a rated range, and the output current is determined by the load; in order to prevent overload from failing, such power supplies often have an overload protection function, that is, when the output load is too large, the current of the primary of the power supply also becomes so large as to trigger the overload protection function inside the chip, and the output is turned off or continuously burped in a gap during overload protection.
The actual load encountered by the power supply in actual use is not a pure resistive load but has the characteristics of capacitance or inductance; for example, if a filter capacitor is connected in parallel to the power supply input terminal of an electrical device, then the load exhibits a capacitive characteristic for the power supply; if a device has a motor inside, then the load presents inductive characteristics for the power supply, since the motor is formed by coil windings; whether inductive or capacitive load is adopted, the characteristic of instant large current load is shown at a moment of starting up, the instant load generated by the capacitive and inductive load is equivalent to the condition of short-circuiting the secondary of a power supply for the rated current of the power supply, and at the moment, if the short-circuit and overload protection function of the power supply is to close the output or continuously perform intermittent hiccup output, the situation that the power supply cannot be started up can occur.
In order to solve the problem, a constant current function can be added on the constant voltage power supply to ensure that the power supply is in a constant current state when the power supply is overloaded or short-circuited, so that the output voltage can be instantly reduced to ensure that the output power does not reach an overload threshold value, and the starting current of the equipment can be continuously supplied, thereby overcoming the condition that the common constant voltage power supply cannot be normally started when meeting capacitive or inductive load!
However, the overload or short circuit is a problem which cannot be easily overcome when the power supply with constant current at the output end is used, namely, the temperature rise is too high. When the secondary is in short circuit, the secondary power supply winding may not output voltage, so that power cannot be supplied to forced refrigeration elements such as a cooling fan and the like, and the temperature is raised too high when the power supply is in short circuit; in addition, when the secondary short circuit occurs, the duty ratio of the secondary rectifying device is small due to low output voltage, the peak current is high, and the secondary rectifying device of the power supply is easy to burn out.
SUMMERY OF THE UTILITY MODEL
The to-be-solved technical problem of the utility model is to above-mentioned problem, provide a timing constant current circuit.
In order to solve the technical problem, the utility model provides a technical scheme does: the utility model provides a timing constant current circuit, includes input rectification filter module, transformer, PWM generator and MCU, the input of input rectification filter module is connected with zero line and live wire, the output of input rectification filter module is connected with the transformer through the live wire, the transformer passes through triode Q1 and is connected with the PWM generator, the transformer is connected with triode Q1's collecting electrode, triode Q1's base and projecting pole are connected with the PWM generator, be connected with opto-coupler PC1B on the PWM generator, parallel connection has electric capacity C2 on the output of transformer, parallel connection has electric capacity C3 on the electric capacity C2, series connection has diode D1 on the output of transformer, be connected with the constant current ring module on the zero line on the transformer output, the constant current ring module is including operational amplifier OP1A, diode D2, resistance R3, R4, R7, zero line series connection of resistance R7 and transformer output, operational amplifier OP 1A's 1 pin passes through diode D2 and is connected with PC1A, PC1A passes through the power supply of amplifier OP 2, operational amplifier OP 2A and the pin and the operational amplifier OP 6A and the pin of the constant voltage amplifier OP 6A, the pin is connected with the MCU through the operational amplifier OP 6A, the pin is connected with the constant voltage amplifier module, the operational amplifier OP 6A through the pin and the operational amplifier module, the operational amplifier OP 6A 6 is connected with the pin.
As an improvement, a pin 2 of the MCU is grounded, a pin 4 of the MCU is connected with a power supply, a capacitor C4 is connected between the pin 2 and the pin 4 of the MCU, and a capacitor C5 is connected between the pin 2 and the pin 3 of the MCU.
As an improvement, a capacitor C1 is connected in parallel to the output end of the input rectifying and filtering module.
As an improvement, a resistor R1 is connected to an emitter of the triode Q1.
Compared with the prior art, the utility model the advantage lie in: the power supply can overcome the defect that the common constant voltage power supply cannot be started when meeting overlarge capacitive or inductive load, and can also overcome the defect that the temperature of elements of the common power supply with the overload or short-circuit constant current function is overhigh when the power supply is short-circuited and constant current.
Drawings
Fig. 1 is a conventional circuit diagram.
Fig. 2 is a schematic circuit diagram of a first embodiment of the present invention.
Fig. 3 is a schematic circuit diagram of a second embodiment of the present invention.
Detailed Description
The present invention will be described in further detail with reference to the accompanying drawings.
Example one
With reference to the accompanying drawing 2, the output end of the input rectifying and filtering module is connected with a transformer through a live wire, the transformer is connected with a PWM generator through a triode Q1, the transformer is connected with a collector of the triode Q1, a base and an emitter of the triode Q1 are connected with the PWM generator, an optocoupler PC1B is connected to the PWM generator, a capacitor C2 is connected in parallel to the output end of the transformer, a capacitor C3 is connected in parallel to the capacitor C2, a diode D1 is connected in series to the output end of the transformer, a constant current loop module is connected to a zero wire at the output end of the transformer, the constant current loop module comprises an operational amplifier OP1A, a diode D2, resistors R3, R4 and R7, the resistor R7 is connected in series with a zero wire at the output end of the transformer, the No. 1A pin of the operational amplifier OP1A is connected with an optocoupler PC1A through a diode D2, the optocoupler PC1A resistor R2 source, the operational amplifier OP1A No. 2 and No. 3 pins are connected with a zero wire at the output end of the transformer through resistors R5 and R4, the OP1A pin of the operational amplifier OP1A 3 a is connected with a zero wire through a resistor R4, the MCU 4 and a resistor R6, the operational amplifier OP1A resistor R7 is connected with a ground resistor R6, the MCU is connected with a resistor R6, the amplifier OP1B and a constant current loop module, the MCU 1B is connected with a resistor R6 and a constant current loop module, the ground resistor R6 and a resistor R6, the ground resistor R6 is connected with the MCU 6, the resistor R6, the amplifier R6 is connected with the amplifier R6 and the resistor R6, the amplifier R6 is connected with the ground resistor R6 and the resistor R7, the amplifier R6.
An over-current detection circuit module is added (the over-current is that the load current exceeds the rated output current capability of the power supply), the over-current detection of the circuit is realized by detecting the output voltage Vout through two divider resistors by an MCU, the MCU is used for setting that the output voltage is judged to be output overload when the output voltage is detected to be lower than a certain threshold value, for example, when the power supply is just started, and the power supply is in short circuit or a very large load suddenly appears, the output voltage can be instantly lower than a certain threshold voltage, when the output voltage is lower than the threshold voltage, the output overload can be judged, and the MCU starts a constant-current timing function. During the timing period, the overcurrent detection module (composed of the MCU and the D4) transmits no signal to the constant current loop module (composed of the OP1A, the D2, the R3, the R4 and the R7); however, after the timing time is over, the over-current detection module sends a level signal to the reference voltage input pin of the operational amplifier in the constant current loop module, so that the operational amplifier OP1A outputs a high level, thereby disabling the constant current loop module.
After the constant current loop loses the action, the constant voltage loop (composed of R6, R8, OP1B and D3) continues to work, and the power supply cannot maintain the state of short circuit or overload constant current; finally, the output end is overloaded, and an overload threshold signal is generated on the primary side heavy current detection resistor R1, and finally, the overload protection function of the PWM generator is triggered, namely the output is turned off or the output is hiccup intermittently.
Example two
With reference to fig. 3, the output end of the input rectifying and filtering module is connected with the transformer through a live wire, the transformer is connected with the PWM generator through a triode Q1, the transformer is connected with the collector of the triode Q1, the base and emitter of the triode Q1 are connected with the PWM generator, the PWM generator is connected with an opto-coupler PC1B, the output end of the transformer is connected with a capacitor C2 in parallel, the capacitor C2 is connected with a capacitor C3 in parallel, the output end of the transformer is connected with a diode D1 in series, the zero line at the output end of the transformer is connected with a constant current loop module, the constant current loop module comprises an OP1A, a diode D2, resistors R3, R4 and R7, the resistor R7 is connected with the zero line at the output end of the transformer in series, the pin No. 1A of the OP1A is connected with the opto-coupler PC1A through the diode D2, the opto-coupler PC1A source through a resistor R2, the pins No. 2 and No. 3 of the OP1A are connected with the zero line through resistors R5 and R4, the pin 3 of the OP1A resistor D6 is connected with the ground, the MCU 1A ground resistor R6 is connected with the MCU through a resistor R6, the ground resistor R6 and a resistor R6, the constant voltage amplifier is connected with the MCU 1B, the MCU 6 and the ground resistor R6.
The embodiment is suitable for occasions with smaller output current, such as LED lamps and the like. When a current larger than the rated output current flows through R7, a current detection voltage is generated on R7, the MCU judges that the state is an overload state after detecting that the voltage signal is larger than a certain threshold value, a timing action is generated, and the overcurrent detection module (composed of the MCU and the D4) does not transmit signals to the constant current loop module (composed of OP1A, D2, R3, R4 and R7) during the timing period; however, when the timing time is up, the over-current detection module sends a level signal to the reference voltage input pin of the operational amplifier in the constant current loop module, so that the operational amplifier OP1A outputs a high level, thereby disabling the constant current loop module. After the constant current loop loses the action, the constant voltage loop (composed of R6, R8, OP1B and D3) continues to work, and the power supply cannot maintain the state of short circuit or overload constant current; finally, the output end is overloaded, and an overload threshold signal is generated on the primary side heavy current detection resistor R1, and finally, the overload protection function of the PWM generator is triggered, namely the output is turned off or the output is hiccup intermittently.
The present invention has been described in connection with the embodiments thereof, and the description is not intended to be limiting, and the embodiments shown in the drawings are only one of the embodiments of the present invention, and the actual structure is not limited thereto. In summary, it should be understood that those skilled in the art should also understand the scope of the present invention without inventively designing the similar structure and embodiments of the present invention without departing from the spirit of the present invention.
Claims (4)
1. The utility model provides a timing constant current circuit, includes input rectification filter module, transformer, PWM generator and MCU, the input of input rectification filter module is connected its characterized in that with zero line and live wire: the output end of the input rectifying and filtering module is connected with a transformer through a live wire, the transformer is connected with a PWM (pulse width modulation) generator through a triode Q1, the transformer is connected with a collector of the triode Q1, a base and an emitter of the triode Q1 are connected with the PWM generator, an optocoupler PC1B is connected on the PWM generator, a capacitor C2 is connected on the output end of the transformer in parallel, a capacitor C3 is connected on the capacitor C2 in parallel, a diode D1 is connected on the output end of the transformer in series, a constant current loop module is connected on a zero wire on the output end of the transformer, the constant current loop module comprises an operational amplifier OP1A, a diode D2, resistors R3, R4 and R7, the resistor R7 is connected with a zero wire of the output end of the transformer in series, a pin No. 1 of the operational amplifier OP1A is connected with the optocoupler PC1A through the diode D2, the optocoupler PC1A is connected with a power supply through a resistor R2, pins No. 2 and No. 3 and a pin No. 3 of the operational amplifier OP1A are connected with a zero wire through resistors R5 and R4, a resistor R6 and a resistor R6D 8, the operational amplifier is connected with a ground resistor R6 and a constant voltage amplifier module, the MCU 6 and the MCU 6 is connected with the output end of the transformer, the operational amplifier module, and the operational amplifier.
2. The clocked constant current circuit of claim 1, wherein: no. 2 pin of MCU ground connection, no. 4 pin power connection, it has electric capacity C4 to connect between No. 2 and No. 4 pin of MCU, it has electric capacity C5 to connect between No. 2 and No. 3 pin of MCU.
3. The clocked constant current circuit of claim 1, wherein: and the output end of the input rectifying and filtering module is connected with a capacitor C1 in parallel.
4. The clocked constant current circuit of claim 1, wherein: and the emitter of the triode Q1 is connected with a resistor R1.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202222299378.9U CN217902332U (en) | 2022-08-30 | 2022-08-30 | Timing constant current circuit |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202222299378.9U CN217902332U (en) | 2022-08-30 | 2022-08-30 | Timing constant current circuit |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN217902332U true CN217902332U (en) | 2022-11-25 |
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Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202222299378.9U Active CN217902332U (en) | 2022-08-30 | 2022-08-30 | Timing constant current circuit |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN217902332U (en) |
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2022
- 2022-08-30 CN CN202222299378.9U patent/CN217902332U/en active Active
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