Primary constant current input power supply circuit
By directly connecting the current detection circuit between the main control chip U1 and the transformer TB, the current signal processing is simplified, the response speed of the control chip is improved, and efficient constant current input control is achieved, solving the problems of slow response speed and circuit complexity of traditional switching power supplies in high voltage or wide voltage scenarios.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- ZHONGSHAN BAOLIJIN ELECTRONICS
- Filing Date
- 2025-07-16
- Publication Date
- 2026-04-24
AI Technical Summary
Traditional switching power supplies suffer from slow control chip response and complex circuit structure when dealing with high voltage or wide voltage scenarios, making it difficult to achieve efficient constant current output.
A current detection circuit is adopted between the main control chip U1 and the transformer TB. It is directly connected to the current acquisition terminal of the main control chip. The input current signal of the primary winding of the transformer is fed back to the main control chip through the current detection circuit for reference voltage comparison and adjustment, which simplifies the current signal processing process.
The circuit structure was simplified, the response speed of the control chip was improved, and efficient control of constant current input was achieved.
Smart Images
Figure CN224164772U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to a power supply device, and more particularly to a power supply circuit with primary constant current input. Background Technology
[0002] In existing technologies, the input terminals of general switching power supplies need to cope with various application scenarios such as higher voltages (e.g., three-phase voltage) or wide voltage ranges (e.g., PV photovoltaic), which leads to an increasing demand for wide voltage output and constant current output at the output terminals. Traditional switching power supplies use resistors in the primary winding of the transformer to obtain current signals, which are then compared and amplified through a comparison circuit composed of analog devices such as operational amplifiers. Finally, the control chip adjusts the on-time or duty cycle of the power switching transistors to maintain a constant primary current. This circuit structure is relatively complex, and because the acquired current signal needs to undergo multiple processing steps, the response speed of the control chip is relatively slow. Utility Model Content
[0003] In order to overcome the shortcomings of the prior art, this utility model provides a power supply circuit with primary constant current input.
[0004] The technical solution adopted by this utility model to solve its technical problem is:
[0005] A primary constant current input power supply circuit includes a main control chip U1. The power input terminal of the main control chip U1 is connected to a rectifier circuit, and the output terminal is connected to the primary winding of a transformer TB. A current detection circuit is connected between the main control chip U1 and the transformer TB. The current acquisition terminal of the main control chip U1 is directly connected to the current detection circuit.
[0006] As a further improvement of this utility model, the rectifier circuit includes an AC input section consisting of a fuse F1, a varistor MOV1, a capacitor CX1, a common-mode inductor LF1, a varistor RT1, and a capacitor CX2. The output terminal of the AC input section is connected to the first pin of the main control chip U1. A resistor R5-R7 and a rectifier diode D7 are connected between the first pin of the main control chip U1 and the AC input section. The rectifier circuit also includes a rectifier section consisting of a common-mode inductor LF2, a rectifier bridge BD1, capacitors C23 and C24, and an inductor L3. The output terminal of the rectifier section is connected to the first pin of the primary winding of the transformer TB.
[0007] The current detection circuit includes a field-effect transistor Q2. The drain of the field-effect transistor Q2 is connected to pin 2 of the primary winding of the transformer TB. The gate of the field-effect transistor Q2 is connected to pin 14 of the main control chip U1 through resistors R39 and R37. The source of the field-effect transistor Q2 is divided into two paths: one path is grounded through parallel resistors RCS2 and RCS3, and the other path is connected to pin 11 of the main control chip U1 through resistor R25. A capacitor C28 is connected between the drain and source of the field-effect transistor Q2, and a resistor R38 is connected between the gate and source of the field-effect transistor Q2.
[0008] As a further improvement of this utility model, the current detection circuit also includes a field-effect transistor Q1. The drain of the field-effect transistor Q1 is connected to the first pin of the primary winding of the transformer TB. The gate of the field-effect transistor Q1 is connected to the 13th pin of the main control chip U1 through resistors R33 and R34. The source of the field-effect transistor Q1 is divided into two paths: one path is grounded through resistor RCS1, and the other path is connected to the 12th pin of the main control chip U1 through resistor R31. A capacitor C34 is connected between the drain and source of the field-effect transistor Q2, and a resistor R19 is connected between the gate and source of the field-effect transistor Q2.
[0009] As a further improvement of this utility model, a voltage stabilizing and filtering circuit is connected between the first and second pins of the transformer TB. The voltage stabilizing and filtering circuit includes a fast recovery diode D3, an electrolytic capacitor C11, a capacitor C26, a fast recovery diode D19, resistors R54-R57, a capacitor C6, a resistor R88, a resistor R89, a switching diode D20, a switching diode D20A, and a switching diode D20B.
[0010] As a further improvement of this utility model, the main control chip U1 is connected to the auxiliary winding of the transformer TB. The third pin of the transformer TB is connected to the 16th pin of the main control chip U1 through a fast recovery diode D8, a transistor Q3 and a resistor R8. The fourth pin of the transformer TB is grounded. The third and fourth pins of the transformer TB constitute the auxiliary winding. The fourth pin of the main control chip U1 is divided into two paths: one path is connected to the third pin of the transformer TB through a resistor R15, and the other path is grounded through a resistor R4.
[0011] The beneficial effects of this utility model are as follows: A current detection circuit is connected between the main control chip U1 and the transformer TB. The current acquisition terminal of the main control chip U1 is directly connected to the current detection circuit. The current detection circuit is responsible for feeding back the input current signal of the primary winding of the transformer TB to the main control chip U1. The main control chip U1 compares the reference voltage of the current signal with the preset comparison voltage and flexibly adjusts the input current of the transformer TB according to the comparison result to achieve constant current input. In addition, the comparison and amplification circuit for processing the current signal is eliminated, which not only simplifies the circuit structure but also improves the response speed of the control chip. Attached Figure Description
[0012] The present invention will be further described below with reference to the accompanying drawings and embodiments.
[0013] Figure 1 This is the circuit schematic diagram of this utility model. Detailed Implementation
[0014] To make the objectives, technical solutions, and advantages of this utility model clearer, the present utility model will be further described in detail below with reference to specific embodiments and accompanying drawings. It should be noted that, unless otherwise specified, the embodiments and features of the present utility model can be combined with each other.
[0015] It should be understood that these descriptions are merely exemplary and not intended to limit the scope of this invention.
[0016] The following describes some embodiments of the present invention with reference to the accompanying drawings.
[0017] Reference Figure 1 A primary constant current input power supply circuit includes a main control chip U1. The power input terminal of the main control chip U1 is connected to a rectifier circuit, and the output terminal is connected to the primary winding of a transformer TB. A current detection circuit is connected between the main control chip U1 and the transformer TB. The current acquisition terminal of the main control chip U1 is directly connected to the current detection circuit. In this embodiment, the current detection circuit is responsible for feeding back the input current signal of the primary winding of the transformer TB to the main control chip U1. The main control chip U1 compares the reference voltage of the current signal with a preset comparison voltage and flexibly adjusts the input current of the transformer TB according to the comparison result to achieve constant current input. In addition, the comparison and amplification circuits for processing the current signal are eliminated, which not only simplifies the circuit structure but also improves the response speed of the control chip.
[0018] Specifically, the main control chip U1 uses an OB6683 AC-DC controller, which integrates a transition mode power factor correction controller and a quasi-resonant controller on the same chip. The PFC controller provides a cost-effective power factor optimization solution, while the QR controller offers higher efficiency and lower electromagnetic interference compared to traditional PWM systems. The OB6683 offers higher integration and performance than traditional PFC / PWM systems. The built-in power factor correction controller optimizes power conversion efficiency by reducing system cost. Intelligent PFC switching, zero-current detection, and frequency limiting mechanisms enable higher efficiency under any load conditions.
[0019] The rectifier circuit includes an AC input section consisting of a fuse F1, a varistor MOV1, a capacitor CX1, a common-mode inductor LF1, a varistor RT1, and a capacitor CX2. The output terminal of the AC input section is connected to pin 1 of the main control chip U1. A resistor R5-R7 and a rectifier diode D7 are connected between pin 1 of the main control chip U1 and the AC input section. The rectifier circuit also includes a rectifier section consisting of a common-mode inductor LF2, a rectifier bridge BD1, capacitors C23 and C24, and an inductor L3. The output terminal of the rectifier section is connected to pin 1 of the primary winding of the transformer TB. The rectifier section converts the AC power from the AC input section into DC power. In this embodiment, pin 1 of the main control chip U1 is directly connected to the AC input section, which allows the high voltage or wide voltage input to be used as the chip's startup power supply, enabling rapid chip startup and shortening the startup time.
[0020] The current detection circuit includes a field-effect transistor Q2. The drain of the field-effect transistor Q2 is connected to pin 2 of the primary winding of the transformer TB. The gate of the field-effect transistor Q2 is connected to pin 14 of the main control chip U1 through resistors R39 and R37. The source of the field-effect transistor Q2 is divided into two paths: one path is grounded through parallel resistors RCS2 and RCS3, and the other path is connected to pin 11 of the main control chip U1 through resistor R25. A capacitor C28 is connected between the drain and source of the field-effect transistor Q2, and a resistor R38 is connected between the gate and source of the field-effect transistor Q2. In this embodiment, the field-effect transistor Q2 serves as the core component for current detection. Its drain is connected to pin 2 of the primary winding of the transformer TB, and its source is grounded through parallel resistors RCS2 and RCS3, forming a current detection path. The voltage rise and fall across resistors RCS2 and RCS3 can reflect the magnitude of the current flowing through the field-effect transistor Q2, thereby realizing current detection. The detected current signal is transmitted to the main control chip U1, where it is amplified and compared. Based on the comparison result, the level of pin 14 is controlled to control the switching state of the field-effect transistor Q2, thereby controlling the current in the primary winding.
[0021] The current detection circuit also includes a field-effect transistor (FET) Q1. The drain of FET Q1 is connected to pin 1 of the primary winding of the transformer TB. The gate of FET Q1 is connected to pin 13 of the main control chip U1 through resistors R33 and R34. The source of FET Q1 is divided into two paths: one is grounded through resistor RCS1, and the other is connected to pin 12 of the main control chip U1 through resistor R31. A capacitor C34 is connected between the drain and source of FET Q2, and a resistor R19 is connected between the gate and source of FET Q2. Similarly, FET Q1 and resistor RCS1 are used to detect the current at pin 1 of the transformer TB. The current detection circuit simultaneously detects the current at both pins of the primary winding of the transformer TB, and performs comprehensive processing based on the two currents to improve control accuracy and achieve constant current.
[0022] A voltage regulator and filter circuit is connected between pin 1 and pin 2 of the transformer TB. This circuit includes a fast recovery diode D3, electrolytic capacitor C11, capacitor C26, fast recovery diode D19, resistors R54-R57, capacitor C6, resistors R88 and R89, switching diodes D20, D20A, and D20B. This circuit smooths the input voltage and current. In this embodiment, resistors R54-R57 and capacitor C6 are connected in parallel across fast recovery diode D19. Fast recovery diode D19, resistor R89, and switching diode D20B are connected in series between pin 1 and pin 2 of the transformer TB. Resistor R88 is connected in parallel across resistor R89, and switching diodes D20 and D20A are connected in parallel across switching diode D20B.
[0023] The main control chip U1 is connected to the auxiliary winding of the transformer TB. Pin 3 of the transformer TB is connected to pin 16 of the main control chip U1 via a fast recovery diode D8, a transistor Q3, and a resistor R8. Pin 4 of the transformer TB is grounded. Pins 3 and 4 of the transformer TB constitute the auxiliary winding. Pin 4 of the main control chip U1 is split into two paths: one path is connected to pin 3 of the transformer TB via a resistor R15, and the other path is grounded via a resistor R4. The high-voltage DC power is stepped down by the transformer TB and then output as a low voltage by the auxiliary winding to the main control chip U1, providing the chip's operating voltage. In this embodiment, pin 4 of the main control chip U1 serves as an auxiliary feedback input terminal for auxiliary voltage regulation or protection functions.
[0024] Pins 5 and 6 of the transformer TB form a secondary winding, which is used to connect the output load and provide voltage to the load.
[0025] Working principle: High-voltage or wide-voltage AC input is converted into DC by a rectifier circuit. One AC input is sent to the main control chip U1 to provide the chip's startup power. The current detection circuit uses two sets of circuits. Field-effect transistors Q1 and Q2 are respectively set on the primary winding circuit of transformer TB. The voltage rise and fall across resistors RCS1, RCS2, and RCS3 can reflect the magnitude of the current flowing through field-effect transistors Q1 and Q2, thereby realizing current detection. The detected current signal is transmitted to the main control chip U1, where it is amplified and compared. Based on the comparison result, the level of pin 14 is controlled to control the switching state of field-effect transistor Q2, thereby controlling the current in the primary winding.
[0026] Although embodiments of the present invention have been shown and described, those skilled in the art will understand that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the present invention, the scope of which is defined by the claims and their equivalents.
Claims
1. A power supply circuit with primary constant current input, characterized in that... Includes a main control chip U1, whose power input terminal is connected to a rectifier circuit and whose output terminal is connected to the primary winding of a transformer TB. A current detection circuit is connected between the main control chip U1 and the transformer TB, and the current acquisition terminal of the main control chip U1 is directly connected to the current detection circuit. The current detection circuit includes a field-effect transistor Q2. The drain of the field-effect transistor Q2 is connected to pin 2 of the primary winding of the transformer TB. The gate of the field-effect transistor Q2 is connected to pin 14 of the main control chip U1 through resistors R39 and R37. The source of the field-effect transistor Q2 is divided into two paths: one path is grounded through parallel resistors RCS2 and RCS3, and the other path is connected to pin 11 of the main control chip U1 through resistor R25. A capacitor C28 is connected between the drain and source of the field-effect transistor Q2, and a resistor R38 is connected between the gate and source of the field-effect transistor Q2. The main control chip U1 is an AC-DC controller with model number OB6683.
2. The power supply circuit with primary constant current input according to claim 1, characterized in that... The rectifier circuit includes an AC input section consisting of a fuse F1, a varistor MOV1, a capacitor CX1, a common-mode inductor LF1, a varistor RT1, and a capacitor CX2. The output terminal of the AC input section is connected to pin 1 of the main control chip U1. Resistors R5-R7 and a rectifier diode D7 are connected between pin 1 of the main control chip U1 and the AC input section. The rectifier circuit also includes a rectifier section consisting of a common-mode inductor LF2, a rectifier bridge BD1, capacitors C23 and C24, and an inductor L3. The output terminal of the rectifier section is connected to pin 1 of the primary winding of the transformer TB.
3. The power supply circuit with primary constant current input according to claim 1, characterized in that... The current detection circuit also includes a field-effect transistor Q1. The drain of the field-effect transistor Q1 is connected to pin 1 of the primary winding of the transformer TB. The gate of the field-effect transistor Q1 is connected to pin 13 of the main control chip U1 through resistors R33 and R34. The source of the field-effect transistor Q1 is divided into two paths: one path is grounded through resistor RCS1, and the other path is connected to pin 12 of the main control chip U1 through resistor R31. A capacitor C34 is connected between the drain and source of the field-effect transistor Q2, and a resistor R19 is connected between the gate and source of the field-effect transistor Q2.
4. The power supply circuit with primary constant current input according to claim 1, characterized in that... A voltage regulator and filter circuit is connected between pin 1 and pin 2 of the transformer TB. The voltage regulator and filter circuit includes a fast recovery diode D3, an electrolytic capacitor C11, a capacitor C26, a fast recovery diode D19, resistors R54-R57, a capacitor C6, a resistor R88, a resistor R89, a switching diode D20, a switching diode D20A, and a switching diode D20B.
5. The power supply circuit with primary constant current input according to claim 1, characterized in that... The main control chip U1 is connected to the auxiliary winding of the transformer TB. The third pin of the transformer TB is connected to the 16th pin of the main control chip U1 through a fast recovery diode D8, a transistor Q3 and a resistor R8. The fourth pin of the transformer TB is grounded. The third and fourth pins of the transformer TB constitute the auxiliary winding. The fourth pin of the main control chip U1 is divided into two paths: one path is connected to the third pin of the transformer TB through a resistor R15, and the other path is grounded through a resistor R4.