Electronic ballast driving circuit based on PWM control chip

Abstract

The utility model discloses an electronic ballast drive circuit based on a PWM control chip, and relates to the technical field of electronic circuits. The electronic ballast driving circuit based on the PWM control chip comprises a signal input module and a signal adjusting output module, the signal input module comprises a transformer T1 and is used for receiving input signals, the signal adjusting module comprises an adjusting circuit and a discharging circuit, the discharging circuit is connected with the signal input module, and the adjusting circuit is connected with the signal input module. The discharge circuit is connected with the electronic ballast driving circuit and used for ensuring that the electronic ballast driving circuit can normally sweep frequency, and the adjusting circuit is connected with the discharge circuit and used for controlling and outputting signals so as to control the working frequency of the electronic ballast driving circuit. The electronic ballast drive circuit provided by the utility model is used for realizing accurate control of the drive circuit.

Description

TECHNICAL FIELD

[0001] The utility model relates to electronic circuit technical field especially, it relates to an electronic ballast drive circuit based on PWM control chip. BACKGROUND

[0002] In the application field of ultraviolet lamp electronic ballast and other gas discharge lamp electronic ballast application field, in order to start ultraviolet lamp source smoothly, the frequency of main half bridge inverter circuit needs to be controlled to complete the heating of filament and produce the resonant high voltage required for lamp starting. The traditional solution is to use foreign electronic ballast special chip, such as L6574D series, UBA201XX series, etc. These chips have built-in programmable oscillator, analog operational amplifier, comparator, timer, digital gate circuit, etc., which can reach the parameters of frequency maximum value (Fmax), frequency minimum value (Fmin) and time (T) through external parameter adjustment. However, such chips have the problems of poor consistency, high requirement for peripheral circuit parameter matching, unsuitable for high-power occasions, high price and difficult delivery, etc. SUMMARY

[0003] The utility model discloses a kind of electronic ballast drive circuits based on PWM control chip, for realizing accurate control drive circuit.

[0004] To achieve the above object, the utility model provides the following technical scheme:

[0005] A kind of electronic ballast drive circuit based on PWM control chip, comprising:

[0006] Signal input module, including transformer T1, the signal input module is used to receive input signal;

[0007] Signal regulation output module, including regulating circuit and discharge circuit, the discharge circuit is connected with the signal input module, for ensuring that the electronic ballast drive circuit can normally carry out frequency scanning, the regulating circuit is connected with the discharge circuit, for controlling and output signal, to control the operating frequency of the electronic ballast drive circuit.

[0008] Optionally, the regulating circuit includes electrically connected control chip U1, diode D1, transistor Q1, capacitor C2 and resistance R3, the diode D1 is used to protect circuit, the capacitor C2 and resistance R3 are connected to the base of the transistor Q1, the transistor Q1 is used to control frequency variation, the control chip U1 is used to generate PWM signal, and the operating frequency of the electronic ballast drive circuit is controlled.

[0009] Optionally, the control chip U1 is set to the switch power supply chip of pin RT and pin CT of oscillator frequency setting.

[0010] Optionally, the control chip U1 is one of UC3845, SG3525 and TL494.

[0011] Optionally, the discharge circuit comprises a diode D3, a resistor R1, a resistor R2, a capacitor C3 and a transistor Q2, the diode D3 is connected with the transformer T1, the resistor R1 is connected with the diode D3, the resistor R2 and the capacitor C3 are connected in parallel, and the transistor Q2 is used for fast discharge when power failure.

[0012] Optionally, the electronic ballast driving circuit further comprises a power supply module, the power supply module is powered by a +15V power supply, and is used for powering the electronic ballast driving circuit.

[0013] Compared with the prior art, the electronic ballast driving circuit provided by the utility model has the advantages that: on the one hand, the frequency can be accurately and flexibly controlled, the capacity of the capacitor C2 and the resistance values of the resistor R2, the variable resistor RT1 and the variable resistor RT2 are adjusted to accurately adjust the change time T of the frequency from high to low, the highest frequency Fmax and the lowest frequency Fmin, so that the various types of ultraviolet lamp loads or other gas discharge lamp loads can be adapted to, the diversified demand for frequency modulation in different application scenarios can be met, the smooth starting and stable working of the lamp can be ensured, the key processes such as the heating of the lamp filament and the generation of the resonant high voltage required for starting the lamp are completed, and the mode of sweeping the frequency from high to low can be realized, the frequency change law is helpful to optimizing the starting performance and working state of the lamp and improving the adaptability and reliability of the overall circuit; on the other hand, the chip limitation can be overcome, the traditional solution relies on the foreign special chip (such as the L6574D series and the UBA201XX series), and many problems such as poor chip consistency, high requirement for the parameter matching of the peripheral circuit, unsuitability for high-power occasions, high price and difficulty in delivery exist, while the driving circuit of the utility model adopts the common switching power supply chip (such as the UC3845, the SG3525 and the TL494) with an internal oscillator and an oscillator frequency setting pin RT, CT, the chips are widely available, have relatively low cost and stable supply, have relatively loose requirement for the parameter matching of the peripheral circuit, the difficulty and cost of circuit design and production are reduced, and the practicability and popularization of the circuit are improved; on the other hand, the circuit stability can be enhanced, the transistor Q2 is added as a power-down fast discharge triode, and the fast discharge circuit composed of the auxiliary group winding of the transformer, the diode D3, the capacitor C3 and the resistor R2 is added. When working normally, the fast discharge loop has no effect on the electronic ballast driving circuit; when the electronic ballast driving circuit is powered off, the capacitor C2 can be quickly discharged, the transistor Q2 is restored to the state that the positive voltage is almost 0, the circuit can normally complete the change and sweep process of the frequency from the highest to the lowest after each power-on, the problem that the circuit cannot work normally due to power-down is avoided, the stability and reliability of the circuit in the complex power supply environment are significantly improved, and the equipment downtime and maintenance cost caused by the circuit failure are reduced. BRIEF DESCRIPTION OF DRAWINGS

[0014] The accompanying drawings, which are included to provide a further understanding of the utility model, form a part of the utility model and are provided to illustrate the utility model and to explain the utility model, and do not constitute improper limitation on the utility model.

[0015] Figure 1 The structure schematic view of the electronic ballast driving circuit provided by the utility model embodiment.

[0016] Reference signs:

[0017] 1 - signal input module; 2 - discharge circuit; 3 - regulating circuit. DETAILED DESCRIPTION

[0018] In order to make the technical problems, technical solutions and beneficial effects of the utility model clearer, the utility model will be further described in detail below in combination with the drawings and examples. It should be understood that the specific examples described herein are only used to explain the utility model and not to limit the utility model.

[0019] In addition, the terms "first", "second" are only for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of indicated technical features. Therefore, the features limited by "first", "second" can be explicitly or implicitly included one or more features. In the description of the utility model, the meaning of "multiple" is two or more than two, unless otherwise explicitly specified. The meaning of "several" is one or more than one, unless otherwise explicitly specified.

[0020] Please refer to Figure 1 The electronic ballast driving circuit based on the PWM control chip provided by the utility model embodiment comprises a signal input module 1 and a signal adjusting output module, wherein the signal input module 1 comprises a transformer T1, the signal input module 1 is used for receiving an input signal, the signal adjusting output module comprises a regulating circuit 3 and a discharge circuit 2, the discharge circuit 2 is connected with the signal input module 1 and is used for ensuring that the electronic ballast can normally carry out frequency sweep, the regulating circuit 3 is connected with the discharge circuit 2 and is used for controlling and outputting a signal to control the working frequency of the electronic ballast driving circuit.

[0021] In the application, the regulating circuit 3 comprises a control chip U1, a diode D1, a transistor Q1, a capacitor C2 and a resistor R3 connected electrically, the diode D1 is used for protecting the circuit, the capacitor C2 and the resistor R3 are connected to the base of the transistor Q1, the transistor Q1 is used for controlling frequency variation, the control chip U1 is used for generating a PWM signal and controlling the working frequency of the electronic ballast driving circuit.

[0022] Further, the control chip U1 is a switching power supply chip provided with a pin RT and a pin CT of oscillator frequency setting, wherein the RT comprises a variable resistor RT1 and a variable resistor RT2.

[0023] Optionally, the control chip U1 is one of UC3845, SG3525 and TL494, for example, a suitable PWM control chip U1 can be selected according to the required power and frequency range, for example, UC3845 is suitable for occasions with smaller power, SG3525 is suitable for medium power, TL494 is suitable for larger power scenarios, etc.

[0024] In the application, the discharging circuit 2 comprises a diode D3, a resistor R1, a resistor R2, a capacitor C3 and a transistor Q2, the diode D3 is connected with the transformer T1, the resistor R1 is connected with the diode D3, the resistor R2 and the capacitor C3 are connected in parallel, and the transistor Q2 is used for fast discharging when power failure.

[0025] In the application, the electronic ballast driving circuit further comprises a power module, the power module supplies power for the +15V power supply, and is used for supplying power for the electronic ballast driving circuit.

[0026] Working principle: after power-on, the aluminum electrolytic positive pole of the capacitor C2 is at a low level, and the transistor Q1 is in a conductive state, at this time, the resistor of the oscillator of the control chip U1 is equivalent to the variable resistor RT1 and the variable resistor RT2 in parallel, and the highest oscillation frequency Fmax is output. With the slow charging of the resistor R2 to the capacitor C2, the positive pole voltage of the capacitor C2 slowly rises, and the transistor Q1 slowly exits the conductive state. Since the capacitor C2 charging makes the base voltage of the transistor Q1 linearly and slowly rise, the transistor Q1 slowly and linearly enters the cut-off state from the conductive state, and finally makes the frequency of the output PWM linearly and slowly decrease from the highest frequency Fmax to the lowest frequency Fmin through the charging time of the capacitor C2. By adjusting the capacity of the capacitor C2 and the resistance values of the resistor R2, the variable resistor RT1 and the variable resistor RT2, the change time from high to low, the highest frequency Fmax and the lowest frequency Fmin can be adjusted, the mode of the frequency from high to low is realized, and the highest frequency Fmax, the lowest frequency Fmin and the change time T can be set.

[0027] When the circuit works normally, the transistor Q1 is completely cut off, and the lowest frequency Fmin is determined by the variable resistor RT1 and CT. However, if the electronic ballast driving circuit is powered off, since the capacitor C2 is fully charged, if the power is restored immediately, the transistor Q1 will continue to be in the cut-off state, and the circuit cannot complete the change of the frequency from the highest to the lowest. In order to solve the problem, the transistor Q2 is added as a power-off fast discharge transistor, and the base of the transistor Q2 is connected with the transformer auxiliary winding of the electronic ballast driving circuit through the diode D3 rectification and the capacitor C3 filtering. When working normally, since the load is normal, the voltage of the rectified auxiliary winding of the transformer T1 makes the transistor Q2 in the cut-off state, and the discharging circuit 2 composed of the diode D3, the resistor R2, the capacitor C3, the resistor R2 and the transistor Q2 has no effect on the electronic ballast driving circuit. When power failure, the auxiliary winding of the transformer loses energy instantaneously, and the transistor Q2 is immediately turned on to quickly discharge the electricity on the capacitor C2, so that the transistor Q2 can restore to the state that the positive pole voltage is almost 0 every time the power is off, and the circuit can realize the frequency scanning state from the highest to the lowest every time.

[0028] The electronic ballast driving circuit provided by the application has the advantages that: on the one hand, the frequency can be accurately and flexibly controlled, the capacity of the capacitor C2 and the resistance values of the resistor R2, the variable resistor RT1 and the variable resistor RT2 are adjusted to accurately adjust the change time T of the frequency from high to low, the highest frequency Fmax and the lowest frequency Fmin, so that the electronic ballast driving circuit can adapt to various types of ultraviolet lamp loads or other gas discharge lamp loads, meet the diversified demand for frequency modulation in different application scenarios, ensure smooth starting and stable working of the lamp, including completing heating of the lamp filament and generating a resonant high voltage required for starting of the lamp and other key processes, and the frequency from high to low sweep frequency mode can be realized, and the frequency change law is helpful to optimizing starting performance and working state of the lamp and improving adaptability and reliability of the overall circuit; on the other hand, the chip limitation can be overcome, the traditional solution relies on foreign special chips (such as L6574D series and UBA201XX series), and there are many problems such as poor chip consistency, high requirement for matching of peripheral circuit parameters, unsuitability for high-power occasions, high price and difficulty in delivery. The driving circuit of the application adopts a common switching power supply chip (such as UC3845, SG3525 and TL494) with an internal oscillator and an oscillator frequency setting pin RT, CT, the chips are widely available, have relatively low cost and stable supply, have relatively loose requirement for matching of peripheral circuit parameters, and the difficulty and cost of circuit design and production are reduced, and the practicability and generalizability of the circuit are improved; on the other hand, the circuit stability can be improved, the transistor Q2 is added as a power-down fast discharge transistor, and the discharge circuit 2 composed of the auxiliary group winding of the transformer, the diode D3, the capacitor C3 and the resistor R2. When the electronic ballast driving circuit is normally working, the discharge circuit 2 has no effect on the electronic ballast driving circuit; when the electronic ballast driving circuit is powered off, the capacitor C2 can be quickly discharged, the transistor Q2 is restored to a state in which the positive voltage is almost 0, and it is ensured that the circuit can normally complete the change sweep frequency process of the frequency from the highest to the lowest after each power-on, the problem that the circuit cannot normally work due to power-down is avoided, and the stability and reliability of the circuit in a complex power supply environment are significantly improved, and the equipment downtime and maintenance cost caused by circuit failure are reduced.

[0029] In the description of the above embodiments, specific features, structures, materials or characteristics can be combined in any one or more embodiments or examples in a suitable manner.

[0030] The above is only a specific implementation manner of the application, but the protection scope of the application is not limited thereto, any person skilled in the art can easily think of changes or replacements within the technical range disclosed by the application, which should be covered in the protection scope of the application. Therefore, the protection scope of the application should be subject to the protection scope of the claims.

Claims

1. A PWM control chip-based electronic ballast driving circuit, characterized in that, The utility model relates to an electronic ballast drive circuit, including: Signal input module, including transformer T1, the signal input module is used for receiving input signal; Signal regulation output module, including regulation circuit and discharge circuit, the discharge circuit is connected with the signal input module, is used for ensuring that the electronic ballast drive circuit can carry out frequency sweep normally, the regulation circuit is connected with the discharge circuit, is used for controlling and output signal, to control the working frequency of electronic ballast drive circuit.

2. The PWM control chip based electronic ballast drive circuit according to claim 1, wherein, The regulation circuit includes electrically connected control chip U1, diode D1, transistor Q1, capacitor C2 and resistance R3, the diode D1 is used for protecting circuit, the capacitor C2 and resistance R3 are connected to the base of transistor Q1, the transistor Q1 is used for controlling frequency variation, the control chip U1 is used for generating PWM signal and controlling the working frequency of electronic ballast drive circuit.

3. The PWM control chip based electronic ballast drive circuit according to claim 2, wherein, The control chip U1 is set to the switch power supply chip of the pin RT and the pin CT of oscillator frequency setting.

4. The PWM control chip based electronic ballast drive circuit according to claim 3, wherein, The control chip U1 is one of UC3845, SG3525, TL494.

5. The PWM control chip based electronic ballast drive circuit according to claim 1, wherein, The discharge circuit includes diode D3, resistance R1, resistance R2, capacitor C3 and transistor Q2, the diode D3 is connected with the transformer T1, the resistance R1 is connected with the diode D3, the resistance R2 and the capacitor C3 are connected in parallel, the transistor Q2 is used for fast discharge when power failure.

6. The PWM control chip based electronic ballast drive circuit according to claim 1, wherein, The electronic ballast drive circuit further includes power module, the power module is powered by +15V power supply, is used for power supply for the electronic ballast drive circuit.

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