Constant-current driving power supply

Abstract

The utility model provides a constant-current driving power supply, which comprises an alternating-current input end, a filtering and rectifying module, a transformer, a PWM (Pulse Width Modulation) control module, a driving module, a power factor correction module and a starting auxiliary power supply module, and the driving module, the power factor correction module, the starting auxiliary power supply module and the primary side winding of the transformer are connected with the PWM control module. The alternating current input end, the filtering and rectifying module and the power factor correction module, namely a primary side winding of a transformer, are connected in sequence, the filtering and rectifying module is used for rectifying alternating current into direct current, and the power factor correction module is used for correcting a power factor to reduce harmonic waves. The driving module comprises a driving circuit connected with the PWM control module and a switching tube connected with the driving circuit, and the PWM control module samples the waveform of the primary side winding of the transformer by controlling the switching-on or switching-off of the switching tube, so that the PWM control module outputs constant current; and the starting auxiliary power supply module is also connected with the primary side secondary winding of the transformer and is used for supplying power to the PWM control module.

Description

Technical Field

[0001] The utility model relates to the technical field of LED drive power supplies, and particularly relates to a constant current drive power supply. Background Art

[0002] Today, with the increasingly serious energy crisis and climate change problems, energy conservation and environmental protection have become the focus of social issues. LEDs have received extensive attention due to their many advantages such as high efficiency, energy conservation, environmental protection, long lifespan, rich colors, small size, anti-flicker, high reliability, and convenient regulation. Traditional incandescent lamps are inefficient and consume a large amount of electricity; fluorescent lamps save electricity, but have a short lifespan, are fragile, and their waste contains mercury pollution; high-intensity gas discharge lamps have disadvantages such as low efficiency, high power consumption, short lifespan, and electromagnetic radiation hazards. If LED lighting can replace the current low-efficiency and high-energy-consuming traditional lighting, it will undoubtedly alleviate the increasingly urgent problems of energy shortage and environmental deterioration.

[0003] Due to the volt-ampere characteristics and temperature characteristics of LEDs themselves, LEDs are more sensitive to current than to voltage, so they cannot be directly powered by traditional power supplies. Although traditional LED drive power supplies can achieve LED brightness adjustment, they cannot achieve power factor correction, have a relatively low input power factor, and a large amount of harmonics. Content of the Utility Model

[0004] In order to solve the above problems, the purpose of the utility model is to provide a constant current drive power supply. By adding a power factor correction module between the filter rectification module and the primary side of the transformer, the constant voltage of the transformer bus is maintained, and the problem of large harmonics is improved.

[0005] The utility model is realized through the following technical solutions:

[0006] A constant current drive power supply includes an AC input terminal, a filter rectification module, a transformer, a PWM control module, a drive module, a power factor correction module, and a startup auxiliary power supply module; the drive module, the power factor correction module, the startup auxiliary power supply module, and the primary side winding of the transformer are all connected to the PWM control module;

[0007] The AC input terminal, the filter rectification module, the power factor correction module, and the primary side winding of the transformer are connected in sequence. The filter rectification module is used to rectify alternating current into direct current, and the power factor correction module is used to correct the power factor to reduce harmonics;

[0008] The driving module includes a driving circuit connected to the PWM control module and a switching transistor connected to the driving circuit. The switching transistor is connected to the primary side winding of the transformer. The PWM control module samples the waveform of the primary side winding of the transformer by controlling the conduction or cutoff of the switching transistor, so that the PWM control module outputs a constant current.

[0009] The startup auxiliary power supply module is also connected to the primary side secondary winding of the transformer for supplying power to the PWM control module.

[0010] Further, the power factor correction module includes a common mode inductor, a first switching transistor, and an electrolytic capacitor. The input end of the common mode inductor is respectively connected to the output end of the filter rectification module and the primary side winding of the transformer. The output end of the common mode inductor is respectively connected to the electrode end of the first switching transistor and the primary side winding of the transformer. The other electrode end and the control end of the first switching transistor are connected to the PWM control module. The positive electrode end of the electrolytic capacitor is connected to the common end of the input end of the common mode inductor and the primary side winding of the transformer, and the other end is grounded.

[0011] Further, a seventh diode is also connected in series between the input end of the common mode inductor and the electrolytic capacitor, and an eighth diode is also connected in series between the common end of the common mode inductor and the switching transistor and the common end of the electrolytic capacitor and the transformer.

[0012] Further, the startup auxiliary power supply module includes a rectification component connected to the input end of the filter rectification module, a fast power supply component connected to the rectification component, and an auxiliary power supply component connected to the primary side secondary winding of the transformer. Both the fast power supply component and the auxiliary power supply component are connected to the PWM control module. The fast power supply component is used to supply power to the PWM control module during circuit startup, and the auxiliary power supply component is used to supply power to the PWM control module after the circuit is stable and cut off the power supply of the fast power supply component to the PWM control module.

[0013] Further, the constant current driving power supply further includes a controllable current module. One end of the controllable current module is connected to the primary side winding of the transformer through the switching transistor, and the other end is connected to the PWM control module. The controllable current module is used to switch the access resistance value of the sampling resistor, thereby changing the magnitude of the constant current output by the PWM control module.

[0014] Further, the constant current driving power supply further includes a thyristor dimming detection module. The thyristor dimming detection module is connected between the PWM control module and the AC input end. The PWM control module reads the voltage waveform of the AC input end through the thyristor dimming detection module.

[0015] Further, the constant current drive power supply further includes an over-temperature protection module, which is connected to the PWM control module and is configured to send a shutdown signal to the PWM control module when the temperature exceeds a preset value.

[0016] Further, the constant current drive power supply further includes an over-voltage protection module, which is connected between the secondary winding on one side of the transformer and the PWM control module and is configured to detect whether the output voltage of the transformer is over-voltage.

[0017] Further, the constant current drive power supply further includes a surge suppression module connected in sequence. The input end of the surge suppression module is connected to the AC input end, and the output end is connected to the input end of the filter rectification module; the surge suppression module is configured to protect the circuit during voltage surges.

[0018] Further, an output rectification and filtering module is provided between the secondary side winding of the transformer and the output end, and is configured to rectify and filter the output voltage of the transformer.

[0019] Compared with the prior art, the technical solution and its beneficial effects of the present utility model are as follows:

[0020] (1) By adding a power factor correction module between the filter rectification module and the primary side winding of the transformer, the present utility model keeps the bus voltage of the transformer constant, so that the current follows the voltage better, achieves power factor correction, and further reduces harmonics.

[0021] (2) For the controllable current module of the present utility model, the access resistance value of the sampling resistor is switched through a DIP switch, so that the PWM control module can output constant currents of different magnitudes.

[0022] (3) At the initial stage of circuit startup, the startup auxiliary power supply module of the present utility model supplies power to the PWM control module through the rectification component and the fast power supply component. After the circuit is stable, the auxiliary power supply component supplies power to the PWM control module, and the power supply of the fast power supply component is cut off, thereby reducing the power consumption of the entire power supply. Description of the Drawings

[0023] Figure 1 is a schematic block diagram of a constant current drive power supply provided by an embodiment of the present utility model;

[0024] Figure 2 is a schematic circuit diagram of the surge suppression module and the filter rectification module provided by an embodiment of the present utility model;

[0025] Figure 3 is a schematic circuit diagram of the power factor correction module provided by an embodiment of the present utility model;

[0026] Figure 4It is the circuit schematic diagram of the thyristor dimming detection module provided by the embodiment of the present utility model;

[0027] Figure 5 It is the circuit schematic diagram of the startup auxiliary power supply module provided by the embodiment of the present utility model;

[0028] Figure 6 It is the circuit schematic diagram of the drive module, controllable current module, overvoltage protection module and overtemperature protection module provided by the embodiment of the present utility model.

[0029] Illustration:

[0030] AC input terminal - 10; surge suppression module - 20; filter rectification module - 30; power factor correction module - 40; drive module - 50; startup auxiliary power supply module - 60; controllable current module - 70; thyristor dimming detection module - 80, overtemperature protection module - 90; overvoltage protection module - 100. Specific embodiments

[0031] To make the objectives, technical solutions and advantages of the embodiments of the present utility model clearer, the technical solutions in the embodiments of the present utility model will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present utility model. Obviously, the described embodiments are some, but not all, of the embodiments of the present utility model. It should be understood that the specific embodiments described herein are only used to explain the present utility model and are not used to limit the present utility model. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present utility model without making creative efforts shall fall within the protection scope of the present utility model.

[0032] Refer to Figure 1 , a constant current drive power supply, including an AC input terminal, a transformer TR1, a PWM control module, a drive module, a power factor correction module, and a startup auxiliary power supply module. The drive module, the power factor correction module, the startup auxiliary power supply module, and the primary side winding of the transformer TR1 are all connected to the PWM control module. The AC input terminal, the filter rectification module, the power factor correction module, and the primary side winding of the transformer TR1 are connected in sequence. The filter rectification module is used to rectify the alternating current into direct current, and the power factor correction module is used to correct the power factor to reduce harmonics.

[0033] The drive module includes a drive circuit connected to the PWM control module and a switching transistor Q5 connected to the drive circuit. The switching transistor Q5 is connected to the primary side winding of the transformer TR1. The PWM control module samples the waveform of the primary side winding of the transformer TR1 by controlling the conduction or cutoff of the switching transistor Q5, so that the PWM control module outputs a constant current.

[0034] The alternating current at the AC input terminal is converted into direct current by the filter rectification module to supply power to the PWM control module. The direct current after passing through the filter rectification module is transmitted to the primary side winding of the transformer TR1 after passing through the power factor correction module. The drive module obtains the primary side feedback (primary side secondary winding) of the transformer TR1 and realizes constant current output through the current sampling of the PWM control module. By setting up a power factor correction module, the constant voltage of the transformer bus is maintained, so that the current can better follow the voltage, achieving power factor correction and further reducing harmonics.

[0035] Refer to Figure 2 , a surge suppression module 20 and a filter rectification module 30 are sequentially connected between the primary side winding of the transformer TR1 and the AC input terminal 10. The input end of the surge suppression module 20 is connected to the AC input terminal 10, and the output end of the filter rectification module 30 is connected to the primary side winding of the transformer TR1. The commercial power passes through the fuse F1 set on the live wire and then passes through the varistor RV1 connected in parallel between the live wire and the neutral wire, playing an anti-surge effect. In this embodiment, the varistor RV1 passes the lightning protection test with a differential mode of 1 KV and a common mode of 2 KV. The EMC filter rectification module is used to convert the AC voltage into a DC voltage and perform EMC filtering.

[0036] Refer to Figure 3 , the PWM control module includes a drive power chip U1. In this embodiment, the drive power chip U1 adopts IW3617. The power factor correction module 40 includes an inductor L5, a first switching tube Q1, and an electrolytic capacitor CE1; the input end of the inductor L5 is respectively connected to the output end of the filter rectification module and the primary side winding of the transformer TR1, the output end of the inductor L5 is respectively connected to the electrode end of the first switching tube Q1 and the primary side winding of the transformer TR1, the other electrode end of the first switching tube Q1 is connected to the BI SENSE pin of the drive power chip U1, the control end of the first switching tube Q1 is connected to the B DRV pin of the drive power chip U1, the positive extreme of the electrolytic capacitor CE1 is connected to the common end of the input end of the inductor L5 and the primary side winding of the transformer TR1, and the other end is grounded. A seventh diode D7 is also connected in series between the input end of the inductor L5 and the electrolytic capacitor CE1, and an eighth diode D8 is also connected in series between the common end of the inductor L5 and the first switching tube Q1 and the common end of the electrolytic capacitor CE1 and the transformer TR1.

[0037] When the drive power chip U1 controls the first switching tube Q1 to conduct, the inductor L5 and the first switching tube Q1 form a loop, and energy is stored in the inductor L5. When the drive power chip U1 controls the first switching tube Q1 to turn off, the energy stored in the inductor L5 and the rectified voltage jointly charge the capacitor CE1 to complete the energy conversion.

[0038] The AC input voltage is converted into a DC voltage after passing through the rectifier bridge DB1. The driving power supply chip U1 compensates for the phase difference between the input current and voltage, making the input current waveform synchronized with the input voltage waveform, thereby improving the power factor. The first switching transistor Q1 controls the charging and discharging of the inductor L5 through the signal provided by the driving power supply chip U1 to achieve PWM control. The inductor L5 and the capacitor CE1 are used for energy storage and filtering, boosting the voltage and filtering out the ripple in the voltage to improve the stability of the output voltage. Thereby improving the utilization rate of electric power, reducing the harmonic content, and solving the electromagnetic interference and electromagnetic compatibility problems caused by the distortion of the current waveform.

[0039] Refer to Figure 4 , the constant current driving power supply further includes a thyristor dimming detection module 80. The thyristor dimming detection module 80 is connected to the V IN pin of the driving power supply chip U1 and the AC input terminal. The PWM control module reads the voltage waveform of the AC input terminal through the thyristor dimming detection module 80. Specifically, the V IN pin of the driving power supply chip U1 reads the voltage waveform of the AC input terminal through the voltage dividing circuit composed of the resistor R8, resistor R10, resistor R33, resistor R35, capacitor C6, and zener diode DW2. If the duty cycle > preset value (such as 90%) in two AC half-cycles, it is considered that no dimmer is connected. The digital circuit inside the driving power supply chip U1 determines the type of the tangential signal by detecting the change rate of the AC input voltage waveform, thereby determining the type of the matched thyristor dimmer. According to the detected voltage conduction angle, it is converted into the duty cycle of the driving circuit through the digital circuit inside the driving power supply chip U1 to change the output current and achieve dimming. This voltage dividing signal can be used for under-voltage and over-voltage protection of the circuit. During the circuit startup period, the voltage divided voltage input to the V IN pin can provide a charging current for the driving power supply chip U1.

[0040] Refer to Figure 5 , the startup auxiliary power supply module 60 includes a rectifying component connected to the input terminal of the filtering and rectifying module, a fast power supply component connected to the rectifying component, and an auxiliary power supply component connected to the secondary winding of the primary side of the transformer. Both the fast power supply component and the auxiliary power supply component are connected to the PWM control module. The fast power supply component is used to supply power to the PWM control module during circuit startup, and the auxiliary power supply component is used to supply power to the PWM control module after the circuit is stable and cut off the power supply of the fast power supply component to the PWM control module.

[0041] Specifically, the rectification component includes diodes D1 and D2 connected in reverse, and the AC voltage is rectified by the rectification component. The fast power supply component includes a current-limiting resistor group and a switching transistor Q2. The current-limiting resistor group includes resistors R45, R12, R13, R14, and R15 connected in sequence. The common terminal of resistors R13 and R14 is connected to the output terminal of the rectification component. The other end of resistor R45 is connected to the collector of switching transistor Q2. The base of switching transistor Q2 is connected to the other end of resistor R15 and is also connected to the ASU pin of the drive power supply chip U1. The emitter of switching transistor Q2 is connected to the auxiliary power supply component and the ACC pin of the drive power supply chip U1. When the circuit is turned on, the direct current provided by the rectification component makes switching transistor Q2 conduct, thus conducting to the ACC pin of the drive power supply chip U1 to supply power to the drive power supply chip U1. Switching transistor Q2 amplifies to enable the internal control circuit of the drive power supply chip U1 to start quickly and prevent the drive power supply chip U1 from being broken down due to lightning strike tests. The auxiliary power supply component includes diode D12, resistor R32, resistor R21, zener diode DW1, electrolytic capacitor CE2, electrolytic capacitor CE3, capacitor C10, and the primary side secondary winding of transformer TR1. The primary side secondary winding of transformer TR1 is connected to the collector of switching transistor Q3 after being connected in series with diode D12 and resistor R32. The emitter of switching transistor Q3 is connected to the VCC pin of the drive power supply chip U1. A resistor R21 is connected between the collector and the base of switching transistor Q3. After the drive power supply chip U1 works stably, the induced electricity of the primary side secondary winding of transformer TR1 is transmitted to the collector and the base of switching transistor Q3, and switching transistor Q3 conducts, and switching transistor Q2 cuts off, so as to realize switching to the auxiliary power supply component to continuously supply power to U1 and automatically cut off the power supply of the fast power supply component composed of resistors R12, R13, R14, R15, R45, and switching transistor Q2, thereby reducing the power consumption of the entire drive.

[0042] Refer to Figure 6 , the drive module includes a drive circuit connected to the drive power supply chip U1 and a switching transistor Q5 connected to the drive circuit. The drain of switching transistor Q5 is connected to the primary side winding of transformer TR1. The gate of switching transistor Q5 is connected to the F DRV pin of the drive power supply chip U1 through resistor R23. The source of switching transistor Q5 is connected to the FI SENSEThe pins are connected. The driving power supply chip U1 samples the primary current waveform of the flyback transformer TR1 by controlling the conduction or cut-off of the switching transistor Q5 and converts it into a waveform related to the secondary current. After high-frequency filtering, error amplification, and integration inside the driving power supply chip U1, it is compared with a comparator to make the driving power supply chip U1 output a constant current. A diode D10 is connected in parallel across both ends of the resistor R23 for rapid discharge when the switching transistor Q5 is cut off; a resistor R22 is connected between the gate and source of the switching transistor Q5, and the resistor R22 is a DC discharge resistor to prevent electrostatic breakdown of the switching transistor Q5.

[0043] Continue to refer to Figure 6 , and it further includes a controllable current module 70. The controllable current module 70 is connected to the primary side winding of the transformer TR1 through the switching transistor Q5 and is connected to the FI SENSE pin of the driving power supply chip U1 through the resistor R24. The controllable current module is used to switch the access resistance value of the sampling resistor, thereby changing the magnitude of the constant current output by the driving power supply chip U1. The controllable current module 70 includes several parallel resistors. One end of the several parallel resistors is connected to the resistor R24, and the other end is connected to a DIP switch SW1. The DIP switch SW1 is grounded, and the sampling resistor is shunted by switching the DIP switch SW1 to achieve different current outputs. The resistor R24 and the capacitor C13 filter the primary peak current of the sampling transformer TR1 for the driving power supply chip U1.

[0044] Continue to refer to Figure 6 , and the constant current driving power supply further includes an overvoltage protection module 100 connected to the PWM modulation driving power supply chip U1. The overvoltage protection module 100 includes resistors R36, R28, and R25 connected in series across both ends of the secondary winding of the primary side of the transformer. The series-connected resistor 37 and the zener diode DW3 are connected in parallel across the two ends far from each other of the resistor R28 and the resistor R25. The common end of the resistor R28 and the resistor R25 is connected to the FV SENSE pin of the driving power supply chip U1. The driving power supply chip U1 compares the divided voltage circuit composed of the resistors R36, R28, R25, R37, and the zener diode DW3 with the internal reference voltage to detect whether the output voltage has an overvoltage.

[0045] Continue to refer to Figure 6, the constant current drive power supply further includes an over-temperature protection module connected to the VT pin of the drive power supply chip U1. The over-temperature protection module includes a resistor group and a capacitor C7 connected in parallel across the resistor group. The resistor group includes a series-connected resistor R16 and a thermistor NTC1, and the other end of the thermistor NTC1 is grounded. When the temperature exceeds the set value, the resistance of the thermistor NTC1 decreases as the temperature rises, causing the set value to be lower than the internal reference of the drive power supply chip U1, reaching undervoltage, thereby shutting down the chip and stopping operation, playing a role in protecting the drive power supply chip U1.

[0046] The above description shows and describes the preferred embodiments of the present invention. It should be understood that the present invention is not limited to the form disclosed herein, should not be regarded as excluding other embodiments, but can be used in various other combinations, modifications, and environments, and can be changed within the scope of the present invention's concept through the above teachings or the technology or knowledge in related fields. And any changes and modifications made by those skilled in the art without departing from the spirit and scope of the present invention should fall within the protection scope of the appended claims of the present invention.

Claims

1. A constant current driving power supply, characterized in that: It includes an AC input terminal, a filter and rectifier module, a transformer, a PWM control module, a drive module, a power factor correction module, and a start-up auxiliary power supply module; the drive module, the power factor correction module, the start-up auxiliary power supply module, and the primary winding of the transformer are all connected to the PWM control module; The AC input terminal, the filter and rectifier module, and the power factor correction module, i.e., the primary winding of the transformer, are connected in sequence. The filter and rectifier module is used to rectify the AC power into DC power, and the power factor correction module is used to correct the power factor to reduce harmonics. The driving module includes a driving circuit connected to the PWM control module and a switch tube connected to the driving circuit, the switch tube is connected to the primary winding of the transformer, and the PWM control module samples the waveform of the primary winding of the transformer by controlling the on or off of the switch tube, so that the PWM control module outputs a constant current; The startup auxiliary power supply module is also connected to the primary-side secondary winding of the transformer to supply power to the PWM control module.

2. A constant current driving power supply according to claim 1, characterized in that: The power factor correction module includes a common-mode inductor, a first switch tube and an electrolytic capacitor; the input end of the common-mode inductor is respectively connected to the output end of the filter rectifier module and the primary winding of the transformer, the output end of the common-mode inductor is respectively connected to the electrode end of the first switch tube and the primary winding of the transformer, the other electrode end of the first switch tube and the control end of the first switch tube are connected to the PWM control module, the positive end of the electrolytic capacitor is connected to the input end of the common-mode inductor and the common end of the primary winding of the transformer, and the other end is grounded.

3. A constant current driving power supply according to claim 2, characterized in that: A seventh diode is connected in series between the input end of the common-mode inductor and the electrolytic capacitor, and an eighth diode is connected in series between the common end of the common-mode inductor and the switch tube and the common end of the electrolytic capacitor and the transformer.

4. A constant current driving power supply according to claim 1, characterized in that: The startup auxiliary power supply module includes a rectifier component connected to the input end of the filter rectifier module, a fast power supply component connected to the rectifier component, and an auxiliary power supply component connected to the primary side secondary winding of the transformer. The fast power supply component and the auxiliary power supply component are both connected to the PWM control module. The fast power supply component is used to supply power to the PWM control module when the circuit is started, and the auxiliary power supply component is used to supply power to the PWM control module after the circuit is stable, and to cut off the power supply of the fast power supply component to the PWM control module.

5. A constant current driving power supply according to claim 1, characterized in that: It also includes a controllable current module, one end of which is connected to the primary winding of the transformer through the switch tube, and the other end is connected to the PWM control module. The controllable current module is used to switch the access resistance value of the sampling resistor, thereby changing the size of the constant current output by the PWM control module.

6. A constant current driving power supply according to claim 1, characterized in that: It also includes a thyristor dimming detection module, which is connected to the PWM control module and the AC input end; the PWM control module reads the voltage waveform of the AC input end through the thyristor dimming detection module.

7. A constant current driving power supply according to claim 1, characterized in that: It also includes an over-temperature protection module, which is connected to the PWM control module and is used to send a shutdown signal to the PWM control module when the temperature exceeds a preset value.

8. A constant current driving power supply according to claim 1, characterized in that: It also includes an overvoltage protection module, which is connected between the secondary winding on one side of the transformer and the PWM control module and is used to detect whether the transformer output voltage is overvoltage.

9. A constant current driving power supply according to claim 1, characterized in that: It also includes a surge suppression module connected in sequence, the input end of the surge suppression module is connected to the AC input end, and the output end is connected to the input end of the filter and rectifier module; the surge suppression module is used to protect the circuit when the voltage surges.

10. A constant current driving power supply according to claim 1, characterized in that: An output rectification and filtering module is provided between the secondary winding and the output end of the transformer, and is used to rectify and filter the output voltage of the transformer.

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