A dimming switch circuit and dimming method based on a ballast

Abstract

This invention relates to the field of electronic circuit technology, specifically to a ballast-based dimming switch circuit and dimming method, including a rectifier module, a first buck module, a second buck module, a sampling module, a control module, an energy storage inductor L1, a freewheeling diode D2, a filter capacitor E2, and a switching transistor T2. This invention uses the control module to control the PWM duty cycle to adjust the ballast output voltage, and simultaneously adjusts the PWM duty cycle by detecting the ballast output voltage, ensuring precise ballast output voltage at each level, thereby achieving dimming.

Description

Technical Field

[0001] This invention relates to the field of dimming switch technology, and specifically to a dimming switch circuit and dimming method based on a ballast. Background Technology

[0002] In recent years, many breakthroughs have been made in the research and development of various new light sources. As people's quality of life improves, their requirements for the living environment have also gradually become new.

[0003] Light-emitting diodes (LEDs) are often used to replace traditional fluorescent lamps due to their advantages such as high luminous efficiency, long lifespan, and low cost. However, traditional fluorescent lamps often require a ballast to drive them, while replacing fluorescent lamps with LEDs requires a compatible circuit with a compatible ballast inside the lamp tube. Since the conduction voltage of the LED beads in the lamp tube is basically a fixed value, and the output current of the ballast can also be considered as approximately constant, the output power of the lamp tube based on the ballast-driven LED switching circuit is also a fixed value, making it impossible to adjust the brightness of the lamp tube. Summary of the Invention

[0004] The purpose of this invention is to address the aforementioned shortcomings in the prior art by providing a ballast-based dimming switch circuit and dimming method that is compatible with high-frequency ballasts and capable of dimming.

[0005] The objective of this invention is achieved through the following technical solution: a dimming switch circuit based on a ballast, comprising a rectifier module, a first step-down module, a second step-down module, a sampling module, a control module, an energy storage inductor L1, a freewheeling diode D2, a filter capacitor E2, and a switching transistor T2;

[0006] The input terminal of the rectifier module is connected to the ballast; the first step-down module is connected to the output terminal of the rectifier module and is used to provide a drive voltage to the switching transistor T2; the second step-down module is used to power the control module; the control terminal of the switching transistor T2 is connected to the control module; the control module is used to output a PWM signal to control the operation of the switching transistor T2; one end of the energy storage inductor L1 is connected to the output terminal of the rectifier module; the other end of the energy storage inductor L1 is connected to the switching terminal of the switching transistor T2 through the filter capacitor E2; one end of the energy storage inductor L1 is connected to the switching terminal of the switching transistor T2 through the freewheeling diode D2.

[0007] The output of the rectifier module is connected to the control module through the sampling module.

[0008] The present invention is further configured such that the rectifier module includes a rectifier bridge BR1; the two input terminals of the rectifier bridge BR1 are respectively connected to a ballast; the negative output terminal of the rectifier bridge BR1 is grounded; the positive output terminal of the rectifier bridge BR1 is respectively connected to one end of the energy storage inductor L1, the first step-down module and the sampling module; a capacitor C1 is provided between the positive output terminal and the negative output terminal of the rectifier bridge BR1.

[0009] The present invention is further configured such that the first step-down module includes a transistor T1, a Zener diode D1, and a resistor R1; one end of the resistor R1 is connected to the output terminal of the rectifier module; the other end of the resistor R1 is connected to the base of the transistor T1; the collector of the transistor T1 is connected to one end of the resistor R1; the base of the transistor T1 is connected to the negative terminal of the Zener diode D1; the positive terminal of the Zener diode D1 is grounded; and the emitter of the transistor T1 is connected to the second step-down module and the switching transistor T2, respectively.

[0010] The present invention is further configured such that the ballast-based dimming switch circuit further includes resistors R2 and R3 and transistor T3; the control module includes a control chip U2; the PWM terminal of the control chip U2 is connected to the base of transistor T3 through resistor R2; the emitter of transistor T3 is grounded; the collector of transistor T3 is connected to one end of resistor R3; the other end of resistor R3 is connected to the emitter of transistor T1; and the collector of transistor T3 is connected to the control terminal of switching transistor T2.

[0011] The present invention is further configured such that the dimming switch circuit based on the ballast also includes a diode D3; the switching transistor T2 is a MOSFET; the source of the MOSFET is grounded; the drain of the MOSFET is connected to the freewheeling diode D2 and the filter capacitor E2 respectively; the gate of the MOSFET is connected to the collector of the transistor T3; the anode of the diode D3 is connected to the source of the MOSFET; and the cathode of the diode D3 is connected to the drain of the MOSFET.

[0012] The present invention is further configured such that the second step-down module includes a step-down chip U3, an inductor E1, and an inductor C2; the input terminal of the step-down chip U3 is grounded through the inductor E1; the output terminal of the step-down chip U3 is grounded through the inductor C2; the input terminal of the step-down chip U3 is connected to the emitter of the transistor T1; and the output terminal of the step-down chip U3 is connected to the power supply terminal of the control module.

[0013] The present invention is further configured such that the sampling module includes resistor R4 and resistor R5; one end of resistor R4 is connected to the output terminal of the rectifier module; the other end of resistor R4 is grounded through resistor R5; and the other end of resistor R4 is connected to the sampling terminal of control chip U2.

[0014] The present invention is further configured such that the ballast-based dimming switch circuit further includes a switch detection module; the switch detection module is connected to the control module;

[0015] The switch detection module includes a diode D4, resistors R7 and R8, a transistor T4, and a resistor R6. One end of resistor R7 is connected to the anode of diode D4; the cathode of diode D4 is connected to the output terminal of the rectifier module; the other end of resistor R7 is grounded through resistor R8; the other end of resistor R7 is connected to the base of transistor T4; the emitter of transistor T4 is grounded; the collector of transistor T4 is connected to the output terminal of the second step-down module through resistor R6; and the collector of transistor T4 is connected to the output terminal of the control module.

[0016] The present invention is further configured such that a switch K1 is connected to the input terminal of the control chip U2.

[0017] A ballast-based dimming method includes a rectifier module, a first step-down module, a second step-down module, a sampling module, a control module, an energy storage inductor L1, a freewheeling diode D2, a filter capacitor E2, and a switching transistor T2; the ballast-based dimming method includes the following steps:

[0018] Rectification step: The voltage output from the ballast is rectified into DC voltage through the rectifier module;

[0019] First step-down step: The DC voltage is stepped down by the first step-down module and a drive voltage is provided for the switching transistor T2;

[0020] The second step-down step: The voltage output by the first step-down module is stepped down by the second step-down module and used to provide voltage to the control module;

[0021] Sampling steps: The control module acquires the DC voltage output by the rectifier module through the sampling module;

[0022] PWM control steps: The control module outputs a PWM signal to the switching transistor T2; the switching transistor T2 switches on and off according to the duty cycle of the PWM signal, thereby changing the DC voltage output by the acquisition and rectification module through the energy storage inductor L1, the freewheeling diode D2, and the filter capacitor E2.

[0023] Fine-tuning steps: The control module compares the DC voltage output by the rectifier module with the preset voltage value and adjusts the duty cycle of the PWM signal output to the switching transistor T2 accordingly.

[0024] The beneficial effects of the present invention are as follows: The present invention uses a control module to control the PWM duty cycle to adjust the output voltage of the ballast, and at the same time, it adjusts the PWM duty cycle by detecting the output voltage of the ballast, so that the output voltage of the ballast at each level is kept accurate, thereby achieving the purpose of dimming. Attached Figure Description

[0025] The invention will be further illustrated with reference to the accompanying drawings, but the embodiments in the drawings do not constitute any limitation on the invention. For those skilled in the art, other drawings can be obtained based on the following drawings without any creative effort.

[0026] Figure 1 This is the circuit diagram of the present invention;

[0027] Figure 2 This is a circuit diagram showing the cooperation between the control module and the sampling module of this invention;

[0028] Figure 3 This is a circuit diagram of the switch detection module of the present invention. Detailed Implementation

[0029] The present invention will be further described in conjunction with the following embodiments.

[0030] Depend on Figures 1 to 3 As can be seen, the dimming switch circuit based on a ballast described in this embodiment includes a rectifier module, a first step-down module, a second step-down module, a sampling module, a control module, an energy storage inductor L1, a freewheeling diode D2, a filter capacitor E2, and a switching transistor T2.

[0031] The input terminal of the rectifier module is connected to the ballast; the first step-down module is connected to the output terminal of the rectifier module and is used to provide a drive voltage to the switching transistor T2; the second step-down module is used to power the control module; the control terminal of the switching transistor T2 is connected to the control module; the control module is used to output a PWM signal to control the operation of the switching transistor T2; one end of the energy storage inductor L1 is connected to the output terminal of the rectifier module; the other end of the energy storage inductor L1 is connected to the switching terminal of the switching transistor T2 through the filter capacitor E2; one end of the energy storage inductor L1 is connected to the switching terminal of the switching transistor T2 through the freewheeling diode D2.

[0032] The output of the rectifier module is connected to the control module through the sampling module.

[0033] Specifically, in traditional LED switching circuit lamps based on ballasts, the LED bead conduction voltage is basically a fixed value, and the ballast output current can also be regarded as approximately constant current. Therefore, the output power of traditional LED switching circuit lamps based on ballasts is also a fixed value, and the brightness of the lamp cannot be adjusted.

[0034] The ballast-based dimming switch circuit described in this embodiment first rectifies the voltage output from the ballast into a DC voltage using a rectifier module. Then, a first step-down module steps down the DC voltage to provide a driving voltage for the switch T2. A second step-down module then steps down the voltage output from the first step-down module to provide a voltage for the control module. When the lamp power needs to be changed, the control module sends PWM signals with different duty cycles to the switch T2 to drive it. Furthermore, the energy storage of the energy storage inductor L1, the energy storage of the freewheeling diode D2, and the filtering effect of the filter capacitor E2 are used to change the DC voltage output from the rectifier module. The size of the voltage output is determined by the rectifier module. Additionally, the control module collects the DC voltage output from the rectifier module via a sampling module. The control module compares the collected DC voltage output from the rectifier module with a preset voltage value, thereby adjusting the duty cycle of the PWM signal output to the switching transistor T2 to ensure accurate DC voltage for each setting. Since the ballast output current can also be considered approximately constant, changing the magnitude of the DC voltage output from the rectifier module can change the output power of the lamp, thus achieving dimming. When the series voltage of the LED beads is 36V, the DC voltage output from the rectifier module can vary between 36V and 180V, providing a wide range of output power adjustment.

[0035] This embodiment describes a ballast-based dimming switch circuit. The rectifier module includes a rectifier bridge BR1. The two input terminals of the rectifier bridge BR1 are connected to the ballast. The negative output terminal of the rectifier bridge BR1 is grounded. The positive output terminal of the rectifier bridge BR1 is connected to one end of an energy storage inductor L1, a first step-down module, and a sampling module. A capacitor C1 is provided between the positive and negative output terminals of the rectifier bridge BR1. By setting the rectifier bridge BR1, the AC voltage output from the ballast can be effectively rectified into a rectified voltage, and the capacitor C1 can filter the DC voltage output from the rectifier bridge BR1.

[0036] This embodiment describes a ballast-based dimming switch circuit. The first step-down module includes a transistor T1, a Zener diode D1, and a resistor R1. One end of resistor R1 is connected to the output terminal of the rectifier module; the other end of resistor R1 is connected to the base of transistor T1; the collector of transistor T1 is connected to one end of resistor R1; the base of transistor T1 is connected to the negative terminal of Zener diode D1; the positive terminal of Zener diode D1 is grounded; and the emitter of transistor T1 is connected to the second step-down module and the switching transistor T2. With this configuration, the DC voltage output from the rectifier bridge BR1 can be effectively converted to 12V and used as the driving voltage for the switching transistor T2.

[0037] This embodiment describes a ballast-based dimming switch circuit, which further includes resistors R2 and R3, and a transistor T3. The control module includes a control chip U2. The PWM terminal of the control chip U2 is connected to the base of the transistor T3 through resistor R2. The emitter of the transistor T3 is grounded. The collector of the transistor T3 is connected to one end of resistor R3. The other end of resistor R3 is connected to the emitter of transistor T1. The collector of the transistor T3 is connected to the control terminal of the switching transistor T2. The control chip U2 is a microcontroller capable of outputting PWM signals, such as CH549. With the above configuration, the control module can send PWM signals with different duty cycles to the switching transistor T2 to drive it.

[0038] This embodiment describes a ballast-based dimming switch circuit, which further includes a diode D3; the switching transistor T2 is a MOSFET; the source of the MOSFET is grounded; the drain of the MOSFET is connected to the freewheeling diode D2 and the filter capacitor E2, respectively; the gate of the MOSFET is connected to the collector of the transistor T3; the anode of the diode D3 is connected to the source of the MOSFET; and the cathode of the diode D3 is connected to the drain of the MOSFET.

[0039] This embodiment describes a ballast-based dimming switch circuit. The second step-down module includes a step-down chip U3, an inductor E1, and an inductor C2. The input terminal of the step-down chip U3 is grounded through inductor E1; the output terminal of the step-down chip U3 is grounded through inductor C2; the input terminal of the step-down chip U3 is connected to the emitter of transistor T1; and the output terminal of the step-down chip U3 is connected to the power supply terminal of the control module. The chip U3 is a 78L05. This configuration effectively converts the 12V output from the first step-down module into a 5V voltage to power the control module.

[0040] This embodiment describes a ballast-based dimming switch circuit. The sampling module includes resistors R4 and R5. One end of resistor R4 is connected to the output terminal of the rectifier module; the other end of resistor R4 is grounded through resistor R5; and the other end of resistor R4 is connected to the sampling terminal of the control chip U2. By setting resistors R4 and R5, a voltage divider is achieved, thereby providing data to the control chip U2 for sampling.

[0041] The ballast-based dimming switch circuit described in this embodiment further includes a switch detection module; the switch detection module is connected to the control module.

[0042] The switch detection module includes a diode D4, resistors R7 and R8, a transistor T4, and a resistor R6. One end of resistor R7 is connected to the anode of diode D4; the cathode of diode D4 is connected to the output terminal of the rectifier module; the other end of resistor R7 is grounded through resistor R8; the other end of resistor R7 is connected to the base of transistor T4; the emitter of transistor T4 is grounded; the collector of transistor T4 is connected to the output terminal of the second step-down module through resistor R6; and the collector of transistor T4 is connected to the output terminal of the control module. In this embodiment, a dimming switch circuit based on a ballast is described, in which the input terminal of the control chip U2 is connected to a switch K1.

[0043] Specifically, the ballast-based dimming switch circuit described in this embodiment, by setting a switch detection module, enables the control module to select different duty cycle PWM signals to control the power of the lamp tube according to the number of times and the duration of the user's switching. In addition, the user can wirelessly control the lamp tube to work through a wireless module.

[0044] The ballast-based dimming method described in this embodiment includes a rectifier module, a first step-down module, a second step-down module, a sampling module, a control module, an energy storage inductor L1, a freewheeling diode D2, a filter capacitor E2, and a switching transistor T2; the ballast-based dimming method includes the following steps:

[0045] Rectification step: The voltage output from the ballast is rectified into DC voltage through the rectifier module;

[0046] First step-down step: The DC voltage is stepped down by the first step-down module and a drive voltage is provided for the switching transistor T2;

[0047] The second step-down step: The voltage output by the first step-down module is stepped down by the second step-down module and used to provide voltage to the control module;

[0048] Sampling steps: The control module acquires the DC voltage output by the rectifier module through the sampling module;

[0049] PWM control steps: The control module outputs a PWM signal to the switching transistor T2; the switching transistor T2 switches on and off according to the duty cycle of the PWM signal, thereby changing the DC voltage output by the acquisition and rectification module through the energy storage inductor L1, the freewheeling diode D2, and the filter capacitor E2.

[0050] Fine-tuning steps: The control module compares the DC voltage output by the rectifier module with the preset voltage value and adjusts the duty cycle of the PWM signal output to the switching transistor T2 accordingly.

[0051] The ballast-based dimming method described in this embodiment adjusts the ballast output voltage by controlling the PWM duty cycle through a control module. Simultaneously, it adjusts the PWM duty cycle by detecting the ballast output voltage to maintain accuracy at each level, thereby achieving the dimming purpose.

[0052] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A dimming switch circuit based on a ballast, characterized in that: It includes a rectifier module, a first buck module, a second buck module, a sampling module, a control module, an energy storage inductor L1, a freewheeling diode D2, a filter capacitor E2, and a switching transistor T2; The input terminal of the rectifier module is connected to the ballast; the first step-down module is connected to the output terminal of the rectifier module and is used to provide a drive voltage to the switching transistor T2; the second step-down module is used to power the control module; the control terminal of the switching transistor T2 is connected to the control module; the control module is used to output a PWM signal to control the operation of the switching transistor T2; one end of the energy storage inductor L1 is connected to the output terminal of the rectifier module; the other end of the energy storage inductor L1 is connected to the switching terminal of the switching transistor T2 through the filter capacitor E2; one end of the energy storage inductor L1 is connected to the switching terminal of the switching transistor T2 through the freewheeling diode D2. The output of the rectifier module is connected to the control module through the sampling module; The first buck module includes a transistor T1, a Zener diode D1, and a resistor R1; one end of the resistor R1 is connected to the output terminal of the rectifier module; the other end of the resistor R1 is connected to the base of the transistor T1; the collector of the transistor T1 is connected to one end of the resistor R1; the base of the transistor T1 is connected to the negative terminal of the Zener diode D1; the positive terminal of the Zener diode D1 is grounded; the emitter of the transistor T1 is connected to the second buck module and the switching transistor T2, respectively. The ballast-based dimming switch circuit further includes resistors R2 and R3, and transistor T3; the control module includes a control chip U2; the PWM terminal of the control chip U2 is connected to the base of transistor T3 through resistor R2; the emitter of transistor T3 is grounded; the collector of transistor T3 is connected to one end of resistor R3; the other end of resistor R3 is connected to the emitter of transistor T1; the collector of transistor T3 is connected to the control terminal of switching transistor T2. The ballast-based dimming switch circuit further includes diode D3; the switching transistor T2 is a MOSFET; the source of the MOSFET is grounded; the drain of the MOSFET is connected to freewheeling diode D2 and filter capacitor E2 respectively; the gate of the MOSFET is connected to the collector of transistor T3; the anode of diode D3 is connected to the source of the MOSFET; and the cathode of diode D3 is connected to the drain of the MOSFET. The input terminal of the control chip U2 is connected to a switch K1.

2. The dimming switch circuit based on a ballast according to claim 1, characterized in that: The rectifier module includes a rectifier bridge BR1; the two input terminals of the rectifier bridge BR1 are respectively connected to the ballast; the negative output terminal of the rectifier bridge BR1 is grounded; the positive output terminal of the rectifier bridge BR1 is respectively connected to one end of the energy storage inductor L1, the first step-down module and the sampling module; a capacitor C1 is provided between the positive output terminal and the negative output terminal of the rectifier bridge BR1.

3. The dimming switch circuit based on a ballast according to claim 1, characterized in that: The second step-down module includes a step-down chip U3, a capacitor E1, and a capacitor C2; the input terminal of the step-down chip U3 is grounded through the capacitor E1; the output terminal of the step-down chip U3 is grounded through the capacitor C2; the input terminal of the step-down chip U3 is connected to the emitter of the transistor T1; and the output terminal of the step-down chip U3 is connected to the power supply terminal of the control module.

4. A ballast-based dimming switch circuit according to claim 1, characterized in that: The sampling module includes resistors R4 and R5; one end of resistor R4 is connected to the output terminal of the rectifier module; the other end of resistor R4 is grounded through resistor R5; and the other end of resistor R4 is connected to the sampling terminal of the control chip U2.

5. A ballast-based dimming switch circuit according to claim 1, characterized in that: The ballast-based dimming switch circuit also includes a switch detection module; the switch detection module is connected to the control module. The switch detection module includes a diode D4, resistors R7 and R8, a transistor T4, and a resistor R6. One end of resistor R7 is connected to the anode of diode D4; the cathode of diode D4 is connected to the output terminal of the rectifier module; the other end of resistor R7 is grounded through resistor R8; the other end of resistor R7 is connected to the base of transistor T4; the emitter of transistor T4 is grounded; the collector of transistor T4 is connected to the output terminal of the second step-down module through resistor R6; and the collector of transistor T4 is connected to the output terminal of the control module.

6. A dimming method based on the dimming switch circuit of the ballast according to any one of claims 1-5, characterized in that, Includes the following steps: Rectification step: The voltage output from the ballast is rectified into DC voltage through the rectifier module; First step-down step: The DC voltage is stepped down by the first step-down module and a drive voltage is provided for the switching transistor T2; The second step-down step: The voltage output by the first step-down module is stepped down by the second step-down module and used to provide voltage to the control module; Sampling steps: The control module acquires the DC voltage output by the rectifier module through the sampling module; PWM control steps: The control module outputs a PWM signal to the switching transistor T2; the switching transistor T2 switches on and off according to the duty cycle of the PWM signal, thereby changing the DC voltage output by the acquisition and rectification module through the energy storage inductor L1, the freewheeling diode D2, and the filter capacitor E2. Fine-tuning steps: The control module compares the DC voltage output by the rectifier module with the preset voltage value and adjusts the duty cycle of the PWM signal output to the switching transistor T2 accordingly.

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