CN105578656B - 120-type 347VAC LED constant-current driving power supply with wide input voltage range - Google Patents

Abstract

The invention relates to an LED constant current driving power supply with a wide input voltage range of 120-plus 347VAC, which comprises an AC input unit, a double FLY-BUCK unit, a power factor adjusting unit, a wide voltage starting unit and an output constant current source unit, wherein the AC input unit comprises an EMC filtering processing circuit and a bridge type full-wave rectifier which are sequentially connected, the input end of the EMC filtering processing circuit is connected to a power supply grid, and the output end of the bridge type full-wave rectifier is connected with the double FLY-BUCK unit, the power factor adjusting unit and the wide voltage starting unit; the power factor adjusting unit and the wide voltage starting unit are connected with the double-FLY-BUCK unit, the double-FLY-BUCK unit comprises a single-stage PFC control circuit, a negative feedback sampling circuit and a double-FLY-BUCK power conversion circuit, the output end of the double-FLY-BUCK power conversion circuit is connected with the output constant current source unit, and the output end of the output constant current source unit is connected with the LED product. The LED constant-current driving power supply realizes indexes that the PF value is not less than 0.9 and the THD value is not more than 20 under the conditions that the input full range is realized and the output load is not less than 50%.

Description

A 120-347VAC wide input voltage range LED constant current drive power supply

technical field

The invention relates to the field of LED lighting driving, in particular to a 120-347V AC input wide range and high index LED constant current driving power supply.

Background technique

At present, in the field of LED lighting driving, LED driving power supplies with wide AC input voltage range generally have a low power factor (Power Factor, PF) value and a low total harmonic distortion (Total Harmonic Distortion, THD) value under the condition of inputting high AC voltage. High, wide voltage range is usually 120-277VAC, although some products are marked as 100-305VAC, but they are essentially the same, and they all take into account the input voltage of 120VAC, 240VAC, and 277VAC. Usually in the case of 277VAC input, the PF value and THD value are poor, especially when the customer actually uses 70% or 50% load current, it is usually difficult to meet the requirements of Energy Star. Therefore, the present invention provides a new type of LED drive power supply with a wide AC input voltage range. The input voltage range can reach 120-347VAC, which can take into account the input voltages of 120VAC, 240VAC, 277VAC, and 347VAC. 277VAC, 347VAC, when the output load is not less than 50%, the PF value is not less than 0.9, and the THD value is not greater than 20, so as to truly realize the green energy-saving and environmental protection LED lighting system for actual use.

Contents of the invention

The present invention aims at the technical problems existing in the existing LED drive power supply, and provides an LED constant current drive power supply with an input voltage of 120-347VAC and which actually meets the requirement of 10% fluctuation of the input voltage within this voltage range. When the output load is not less than 50%, the PF value is not less than 0.9, and the THD value is not more than 20.

In order to achieve the above purpose, the technical solution adopted by the present invention is, a 120-347VAC wide input voltage range LED constant current drive power supply, including AC input unit, double FLY-BUCK unit, power factor adjustment unit, wide voltage starting unit and output constant current source unit, where,

The AC input unit is used to provide pulsating direct current, including an EMC filter processing circuit and a bridge full-wave rectifier connected in sequence, the input end of the EMC filter processing circuit is connected to the power supply grid, and the output end of the bridge full-wave rectifier is connected to the dual FLY-BUCK unit, power factor adjustment unit and wide voltage starting unit;

The power factor adjustment unit is connected with the double FLY-BUCK unit, samples the pulsating DC signal sent through the AC input unit, and obtains the voltage signal, and then compares it with the current signal obtained by the current sampling provided by the double FLY-BUCK unit to complete the voltage, Matching adjustment of current waveform;

Dual FLY-BUCK unit, including single-stage PFC (power factor correction) control circuit, negative feedback sampling circuit and dual FLY-BUCK power conversion circuit, the negative feedback sampling circuit and dual FLY-BUCK power conversion circuit are both integrated with single-stage PFC The control circuit is connected, and two FLY-BUCK power conversion circuits that work in parallel and interleaved are used to realize energy conversion in the full cycle under PWM control mode;

The wide voltage starting unit is connected with the double FLY-BUCK unit, samples the pulsating DC signal sent through the AC input unit, and sends the pulsating DC signal to the single-stage PFC control circuit in the double FLY-BUCK unit after processing to ensure that the control circuit energy supply;

The output constant current source unit, its input terminal is connected to the double FLY-BUCK unit, and the output terminal is connected to the LED product to realize the effective control of the output current, meet the control requirements of the LED product on the output current, and achieve the effect of output constant current and dimming.

As an improvement of the present invention, the single-stage PFC control circuit of the double FLY-BUCK unit adopts the single-stage PFC control chip NCP1652 as the controller, and the controller includes error amplifier, pulse width modulator (PWM), sawtooth wave In addition to the generator and other circuits, it also integrates Soft-Skip circuit, high-voltage start-up circuit, voltage feedforward, power-down detection, input lockout, built-in overload timer and high-precision multiplier, with high integration, few components and low cost Features.

As an improvement of the present invention, the double FLY-BUCK power conversion circuit of the double FLY-BUCK unit includes a first FLY-BUCK power conversion circuit and a second FLY-BUCK power conversion circuit, and the first FLY-BUCK power The input end of the conversion circuit is connected to the OUTA pin of the controller NCP1652 through the gate of the first power switch MOSFET, and the input end of the second FLY-BUCK power conversion circuit is connected to the controller through the gate of the second power switch MOSFET The OUTB pin of NCP1652, the output terminals of the first FLY-BUCK power conversion circuit and the second FLY-BUCK power conversion circuit are all connected to the input terminal of the negative feedback sampling circuit and the input terminal of the output constant current source unit; and in the controller A resistor is connected between the Rdelay pin of the NCP1652 and the signal ground to set the non-overlap time delay between the OUTA pin and the OUTB pin, so that the first power switch MOSFET and the second power switch MOSFET are turned on alternately. The MOSFETs respectively control the first FLY-BUCK power conversion circuit and the second FLY-BUCK power conversion circuit to transfer energy from the input end to the output end.

As an improvement of the present invention, the output end of the bridge full-wave rectifier of the AC input unit is connected to a post-stage filter circuit composed of a first inductor and a first capacitor, and the value range of the first capacitor is 0.1 μF-1.0μF can reduce high switching frequency and provide low impedance power supply for single-stage PFC control circuit.

As an improvement of the present invention, the power factor adjustment unit includes two parallel first resistor voltage divider circuits and second resistor voltage divider circuits, the first resistor voltage divider circuit is connected to the AC IN pin of the controller NCP1652, The sine wave rectified and output by the bridge full-wave rectifier passes through the first resistor divider circuit to input the line voltage information to the multiplier of the controller NCP1652; the second resistor divider circuit is connected to the V _FF pin of the controller NCP1652, and after rectification The filtered line voltage is input to the controller NCP1652 through the second resistor divider circuit for adjusting the controller.

As an improvement of the present invention, the wide voltage starting unit includes a DC starting circuit of the controller NCP1652 and a starting voltage V _CC generating circuit, and the DC starting circuit includes a Schottky diode, a first rectifier diode, a first current limiting The voltage dividing resistor and the second capacitor, the anode of the Schottky diode is connected to the anode of the first rectifier diode, the cathode of the first rectifier diode is connected to the second capacitor and connected to the signal ground, and the cathode of the first rectifier diode is connected in series with the first current limiting The divider resistor is connected with the HV pin of the controller NCP1652; the startup voltage V _CC generating circuit includes a second rectifier diode, a third rectifier diode, a second current-limiting divider resistor, a third capacitor, a fourth capacitor and a coupling Inductor, the anode of the second rectifier diode is connected to the coupled inductor, the cathode of the second rectifier diode is connected to the anode of the third rectifier diode, and the cathode of the third rectifier diode is connected to the Vcc of the controller NCP1652 after being connected in series with the second current-limiting voltage divider resistor pins; one end of the third capacitor is connected between the negative pole of the second rectifier diode and the positive pole of the third rectifier diode, and the other end is connected to the signal ground; one end of the fourth capacitor is connected between the second current-limiting voltage dividing resistor and the Vcc lead Between the pins, the other end is connected to the signal ground.

As an improvement of the present invention, the EMC filter processing circuit includes a fuse, a coupling inductor, a resistor, a fifth capacitor, a second inductor, a sixth capacitor, a seventh capacitor, and an eighth capacitor, and the fuse is connected to the AC grid On the live line of the coupled inductor, the same-named end of the coupled inductor is connected to the neutral line and the live line of the AC power grid, a resistor is connected in parallel to the different-named end of the coupled inductor, and the fifth capacitor and the sixth capacitor are connected in parallel at both ends of the resistor. A second inductor is connected in series between the fifth capacitor and the sixth capacitor, the seventh capacitor is connected in series between the neutral line and the zero protection line, and the eighth capacitor is connected in series between the zero protection line and the second inductor.

As an improvement of the present invention, the first resistor divider circuit includes a first resistor, a second resistor, a third resistor and a fourth resistor connected in series in sequence, a ninth capacitor is connected in parallel at both ends of the fourth resistor, and the first The ends of the four resistors are connected to the signal ground, and a branch is drawn between the third resistor and the fourth resistor to connect to the AC IN pin of the controller NCP1652; the second resistor voltage divider circuit includes the fifth resistor connected in series, The sixth resistor, the seventh resistor and the eighth resistor, the ninth resistor and the tenth capacitor are connected in parallel at both ends of the eighth resistor, the end of the eighth resistor is connected to the signal ground, and the signal ground is drawn between the seventh resistor and the eighth resistor One branch connects the V _FF pin of the controller NCP1652.

As an improvement of the present invention, the first FLY-BUCK power conversion circuit includes a first transformer, a first diode, a tenth resistor, an eleventh capacitor, a first output rectifying diode and a first output capacitor, the first The anode of a diode and the same-named end of the primary side of the first transformer are connected to the drain of the first power switch MOSFET, the tenth resistor and the eleventh capacitor are connected in parallel, and one end is connected to the negative electrode of the first diode, and the other end Connect the primary side of the first transformer with the same name terminal, the secondary terminal of the first transformer with the same name is connected to the positive pole of the first output rectifier diode, the negative pole of the first output rectifier diode is connected to the positive pole of the first output capacitor, and the negative pole of the first output capacitor is connected to the positive pole of the first output capacitor. The secondary opposite end of the first transformer is connected to the analog ground, and a branch is drawn between the negative pole of the first output rectifier diode and the positive pole of the first output capacitor as the first output terminal of the double FLY-BUCK unit; The second FLY-BUCK power conversion circuit includes a second transformer, a second diode, an eleventh resistor, a twelfth capacitor, and a second output rectifier diode, the anode of the second diode and the primary side of the second transformer The terminal with the same name is connected to the drain of the second power switching tube MOSFET, the eleventh resistor and the twelfth capacitor are connected in parallel, and one end is connected to the negative pole of the second diode, and the other end is connected to the original side of the second transformer. The same-named terminal of the secondary side of the second transformer is connected to the anode of the second output rectifier diode, the different-named terminal of the secondary side of the second transformer is connected to the analog ground, and the negative pole of the second output rectifier diode is used as the second output terminal of the double FLY-BUCK unit; The primary opposite end of the first transformer and the second transformer are connected to the output end of the post-stage filter circuit of the AC input unit, and the sources of the first power switching tube MOSFET and the second power switching tube MOSFET are connected and connected in series with the twelfth resistor. Then be connected to the post-stage filter circuit output end of the AC input unit; the negative feedback sampling circuit includes a current/voltage detection circuit and a photoelectric isolator connected in sequence, the first output end and the second output end of the double FLY-BUCK unit On the one hand, it is connected to the current/voltage detection circuit, and on the other hand, it is connected to the output constant current source unit. One of the dual output terminals of the photoelectric isolator is connected to the FB pin of the controller NCP1652 through the thirteenth resistor, and the other is connected to the rear stage of the AC input unit. The output terminal of the filter circuit is connected.

As an improvement of the present invention, the CT pin of the controller NCP1652 is externally connected with a timing capacitor to generate a 0.2V-0.4V sawtooth wave to set the frequency of the oscillator and the gain of the multiplier, and the RAMP COMP pin is connected to the signal ground A resistor is connected between them to adjust the slope compensation added to the current signal to prevent harmonic vibration; the FB pin is connected to an external error amplifier circuit, and the external error amplifier circuit includes a triode, a fourteenth resistor, a thirteenth capacitor and The fourteenth capacitor, one end of the fourteenth resistor is connected to the FB pin, the other end is connected to the base of the triode, one end of the thirteenth capacitor is connected to the FB pin, and the other end is connected to the collector of the triode, the fourteenth capacitor is connected to the triode Between the base and the emitter of the triode, the emitter of the triode is connected to the signal ground; a capacitor is connected between the CM pin and the signal ground to filter the output of the internal multiplier, and a resistor is connected in series between the ACCOMP pin and the signal ground And the capacitor is used as the AC reference amplifier to set the pole. The Latch pin is connected to the signal ground after a resistor is connected in series, the Rdelay pin is connected to the signal ground after a resistor is connected in series, and a resistor and a capacitor are connected externally between the _IAVG pin and the signal ground. The resistor and capacitor are connected in parallel, a resistor and a capacitor are externally connected between the I _SPOS pin and the signal ground, the resistor and the capacitor are connected in parallel, and the I _SPOS pin is connected in series with the fifteenth resistor and connected to the first power switch MOSFET and the second The source of the power switching tube MOSFET, the 16th resistor and the 17th resistor are connected in series between the OUTA pin and the signal ground, and a branch is drawn between the 16th resistor and the 17th resistor to connect the first power The gate of the switching tube MOSFET, the eighteenth resistor and the nineteenth resistor are connected in series between the OUTB pin and the signal ground, and a branch is drawn between the eighteenth resistor and the nineteenth resistor to connect the second power switch tube The gate of the MOSFET, the GND pin is connected to the signal ground, and the signal ground is connected to the analog ground through a coupling capacitor.

Compared with the prior art, the present invention has the following advantages: 1) The LED constant current drive power supply has a simple structure and a wide input voltage range, and can maintain a PF value greater than 0.9 and a THD value lower than 0.2 under nominal input conditions. The full range of 120-347V AC input meets the requirements of Energy Star, and it is a low-cost and high-indicator LED drive solution; 2) The use of dual FLY-BUCK units can fundamentally avoid the When the input AC voltage is high, the PF value and THD value decrease at the same time. In the double FLY-BUCK unit, two parallel FLY-BUCK power conversion circuits are used to realize the full cycle under PWM control mode. Energy conversion, under the same input conditions, the current sampling amplitude at the input terminal is increased, which provides conditions for increasing the PF value and reducing the THD value. The DC ripple current improves the working status of the output constant current source unit of the subsequent stage; 3) For the case of wide input AC voltage range and high input voltage, and in order to achieve a high PF value, the power factor adjustment unit is sampled through the AC input The pulsating DC signal sent by the unit is used to obtain the voltage signal, and then compared with the current signal obtained by the current sampling provided by the dual FLY-BUCK unit, and the matching adjustment of the voltage and current waveforms is completed to obtain a high PF value, which can be used in the full range of AC input When the voltage and output load are not less than 50%, the PF value is not less than 0.9; 4) The wide voltage starting unit is proposed for a wide range of input AC voltage, solving the power supply part of the control circuit, and solving the problem of high-voltage starting and continuous power supply, so that It solves the problem of starting voltage due to low input voltage and high voltage caused by AC input wide voltage, and at the same time provides energy supply for the control part during normal operation of the product; 5) AC input unit includes EMC filter processing circuit connected in sequence, bridge Full-wave rectifier and post-stage filter circuit, EMC filter processing circuit to solve the problem of conduction interference, bridge-type full-wave rectifier completes the function of converting AC input to pulsating DC, and the post-stage filter circuit further performs high-frequency filtering on the pulsating DC signal, which is a double FLY- The BUCK unit provides a low-impedance power supply. The design of the single-stage PFC control circuit using the NCP1652 controller has the advantages of low cost, simple structure, and high work efficiency. At the same time, it improves the inherent shortcomings of the single-stage PFC and accelerates the loop response. Reduce electromagnetic interference signals, reduce noise, and reduce input power frequency harmonics.

Description of drawings

Fig. 1 is the block diagram of circuit principle of the present invention.

Fig. 2 is a schematic circuit diagram of the present invention.

detailed description

In order to deepen the understanding and recognition of the present invention, the present invention will be further described and introduced below in conjunction with the accompanying drawings.

As shown in Figure 1 and Figure 2, a 120-347VAC wide input voltage range LED constant current drive power supply, including AC input unit, double FLY-BUCK unit, power factor adjustment unit, wide voltage starting unit and output constant current source unit. in,

The AC input unit is used to provide pulsating direct current, including an EMC filter processing circuit and a bridge full-wave rectifier connected in sequence, the input end of the EMC filter processing circuit is connected to the power supply grid, and the output end of the bridge full-wave rectifier is connected to the dual FLY-BUCK unit, power factor adjustment unit and wide voltage starting unit.

The power factor adjustment unit is connected with the double FLY-BUCK unit, samples the pulsating DC signal sent through the AC input unit, and obtains the voltage signal, and then compares it with the current signal obtained by the current sampling provided by the double FLY-BUCK unit to complete the voltage, Matching adjustment of current waveform.

Dual FLY-BUCK unit, including single-stage PFC (power factor correction) control circuit, negative feedback sampling circuit and dual FLY-BUCK power conversion circuit, the negative feedback sampling circuit and dual FLY-BUCK power conversion circuit are both integrated with single-stage PFC The control circuits are connected, and two FLY-BUCK power conversion circuits that work in parallel and interleaved are used to realize the energy conversion in the full cycle under the PWM control mode.

The wide voltage starting unit is connected with the double FLY-BUCK unit, samples the pulsating DC signal sent through the AC input unit, and sends the pulsating DC signal to the single-stage PFC control circuit in the double FLY-BUCK unit after processing to ensure that the control circuit energy supply.

The output constant current source unit, its input terminal is connected to the double FLY-BUCK unit, and the output terminal is connected to the LED product to realize the effective control of the output current, meet the control requirements of the LED product on the output current, and achieve the effect of output constant current and dimming.

The output end of the bridge full-wave rectifier BR2 of the AC input unit is connected to a post-stage filter circuit composed of a first inductor L7 and a first capacitor C38, and the value range of the first capacitor C38 is 0.1 μF-1.0 μF , can reduce high switching frequency and provide low impedance power supply for single-stage PFC control circuit. The EMC filter processing circuit includes a fuse F2, a coupling inductor L5, a resistor RP2, a fifth capacitor C36, a second inductor L6, a sixth capacitor C37, a seventh capacitor C19 and an eighth capacitor C21, and the fuse F2 is connected to the AC grid On live wire L4, the same-named end of coupled inductor L5 is connected to the neutral line N1 and live wire L4 of the AC power grid respectively, the opposite-named end of coupled inductor L5 is connected in parallel to resistor RP2, and the two ends of resistor RP2 are sequentially connected in parallel to the fifth The capacitor C36 and the sixth capacitor C37, the second inductor L6 is connected in series between the fifth capacitor C36 and the sixth capacitor C37, the seventh capacitor C19 is connected in series between the neutral line N1 and the zero protection line CASE1, the eighth capacitor C21 It is connected in series between the zero protection line CASE1 and the second inductor L6.

The single-stage PFC control circuit of the double FLY-BUCK unit adopts the single-stage PFC control chip NCP1652 as the controller. The dual FLY-BUCK power conversion circuit includes a first FLY-BUCK power conversion circuit and a second FLY-BUCK power conversion circuit, and the input end of the first FLY-BUCK power conversion circuit passes through the gate of the first power switch MOSFET D15 Connect the OUTA pin P13 of the controller NCP1652, the input terminal of the second FLY-BUCK power conversion circuit is connected to the OUTB pin P14 of the controller NCP1652 through the gate of the second power switch MOSFET D16, the first FLY-BUCK power The output terminals of the conversion circuit and the second FLY-BUCK power conversion circuit are connected to the input terminal of the negative feedback sampling circuit and the input terminal of the output constant current source unit; and a connection between the Rdelay pin P9 of the controller NCP1652 and the signal ground Resistor to set the non-overlap time delay between OUTA pin P13 and OUTB pin P14, so that the first power switch MOSFET D15 and the second power switch MOSFET D16, which are turned on alternately, respectively control the first FLY - BUCK power conversion circuit and a second FLY-BUCK power conversion circuit to transfer energy from the input to the output.

The first FLY-BUCK power conversion circuit includes a first transformer T2, a first diode D8, a tenth resistor R33, an eleventh capacitor C25, a first output rectifying diode D13 and a first output capacitor C28, the first two The anode of the pole tube D8 is connected to the drain of the first power switch MOSFET D15 with the same-named end of the primary side of the first transformer T2, and the tenth resistor R33 is connected in parallel with the eleventh capacitor C25, and the other end is connected to the negative pole of the first diode D8 connected, the other end is connected to the primary side opposite end of the first transformer T2, the secondary end of the first transformer T2 with the same name is connected to the positive pole of the first output rectifier diode D13, and the negative pole of the first output rectifier diode D13 is connected to the first output capacitor C28 Positive pole, the negative pole of the first output capacitor C28 is connected to the opposite terminal of the secondary side of the first transformer T2 and then connected to the analog ground, and a branch is drawn between the negative pole of the first output rectifying diode D13 and the positive pole of the first output capacitor C28 As the first output end of a double FLY-BUCK unit; the second FLY-BUCK power conversion circuit includes a second transformer T3, a second diode D11, an eleventh resistor R34, a twelfth capacitor C27 and a second output The rectifier diode D14, the anode of the second diode D11 and the same-named end of the primary side of the second transformer T3 are connected to the drain of the second power switch MOSFET D16, and the eleventh resistor R34 is connected in parallel with the twelfth capacitor C27. The negative pole of the second diode D11 is connected, and the other end is connected to the opposite terminal of the primary side of the second transformer T3, and the same terminal of the secondary side of the second transformer T3 is connected to the positive pole of the second output rectifier diode D14, and the secondary terminal of the second transformer T3 Connect the opposite end to the analog ground, and the negative pole of the second output rectifier diode D14 leads out as the second output end of the double FLY-BUCK unit; the original opposite end of the first transformer T2 and the second transformer T3 are connected to the rear of the AC input unit The output terminal of the stage filter circuit is connected, the source of the first power switch MOSFET D15 and the second power switch MOSFETD16 are connected, and the twelfth resistor R50 is connected in series and then connected to the output terminal of the post-stage filter circuit of the AC input unit; the negative The feedback sampling circuit includes a current/voltage detection circuit and a photoelectric isolator connected in sequence. The first output terminal and the second output terminal of the double FLY-BUCK unit are connected to the current/voltage detection circuit on the one hand, and the output constant current source unit on the other hand. One of the dual output ends of the photoelectric isolator is connected to the FB pin P4 of the controller NCP1652 through a thirteenth resistor, and the other is connected to the output end of the post-stage filter circuit of the AC input unit.

The power factor adjustment unit includes two parallel first resistor divider circuits and second resistor divider circuits, the first resistor divider circuit is connected to the AC IN pin P3 of the controller NCP1652, and is rectified by a bridge full-wave rectifier The output sine wave passes through the first resistor divider circuit to input the line voltage information to the multiplier of the controller NCP1652; the second resistor divider circuit is connected to the V _FF pin P5 of the controller NCP1652, and the rectified and filtered line voltage passes through the first The two-resistor divider circuit is input to the controller NCP1652 for adjusting the controller.

The first resistor divider circuit includes a first resistor R11, a second resistor R13, a third resistor R14 and a fourth resistor R35 connected in series in sequence, a ninth capacitor C39 is connected in parallel at both ends of the fourth resistor R35, and the fourth resistor The end of R35 is connected to the signal ground, and a branch is drawn between the third resistor R14 and the fourth resistor R35 to connect to the AC IN pin P3 of the controller NCP1652; The resistor R12, the sixth resistor R15, the seventh resistor R26 and the eighth resistor R36, the ninth resistor R37 and the tenth capacitor C40 are connected in parallel at both ends of the eighth resistor R36, the end of the eighth resistor R36 is connected to the signal ground, and the A branch is drawn between the seventh resistor R26 and the eighth resistor R36 to connect to the V _FF pin P5 of the controller NCP1652.

The wide voltage starting unit comprises a DC starting circuit of a controller NCP1652 and a starting voltage V _CC generating circuit, and the DC starting circuit includes a Schottky diode D4, a first rectifying diode D6, a first current-limiting voltage dividing resistor R43 and a first Two capacitors C23, the anode of the Schottky diode D4 is connected to the anode of the first rectifier diode D6, the cathode of the first rectifier diode D6 is connected to the second capacitor C23 and then connected to the signal ground, the cathode of the first rectifier diode D6 is connected in series with the first limiter Connect with the HV pin P16 of the controller NCP1652 after the flow divider resistor R43; The described start-up voltage V _CC generating circuit includes the second rectifier diode D7, the third rectifier diode D12, the second current-limiting divider resistor R27, the third capacitor C47, the fourth capacitor C24 and the coupled inductor, the anode of the second rectifier diode D7 is connected to the coupled inductor, the cathode of the second rectifier diode D7 is connected to the anode of the third rectifier diode D12, and the cathode of the third rectifier diode D12 is connected in series with the second The current-limiting voltage dividing resistor R27 is connected to the Vcc pin P12 of the controller NCP1652; one end of the third capacitor C47 is connected between the negative pole of the second rectifying diode D7 and the positive pole of the third rectifying diode D12, and the other end is connected to the signal ground; One end of the fourth capacitor C24 is connected between the second current-limiting voltage dividing resistor R27 and the Vcc pin P12, and the other end is connected to the signal ground.

The CT pin P1 of the controller NCP1652 is externally connected with a timing capacitor C45 to generate a 0.2V-0.4V sawtooth wave to set the frequency of the oscillator and the gain of the multiplier, and a resistor R41 is connected between the RAMP COMP pin P2 and the signal ground to adjust the slope compensation added to the current signal to prevent harmonic vibration; the FB pin P4 is connected to an external error amplifier circuit, and the external error amplifier circuit includes a triode Q1, a fourteenth resistor R52, a thirteenth capacitor C49 and The fourteenth capacitor C43, one end of the fourteenth resistor R52 is connected to the FB pin P4, the other end is connected to the base of the transistor Q1, one end of the thirteenth capacitor C49 is connected to the FB pin P4, and the other end is connected to the collector of the transistor Q1, The fourteenth capacitor C43 is connected between the base and emitter of the transistor Q1, and the emitter of the transistor Q1 is connected to the signal ground; a capacitor C41 is connected between the CM pin P6 and the signal ground to filter the output of the internal multiplier, AC A resistor R38 and a capacitor C42 are connected in series between the COMP pin P7 and the signal ground as the AC reference amplifier setting pole, the Latch pin P8 is connected in series with a resistor R40 and then connected to the signal ground, and the Rdelay pin P9 is connected in series with a resistor R42 and then connected Connect a resistor R47 and a capacitor C46 between the I _AVG pin P10 and the signal ground, the resistor R47 and the capacitor C46 are connected in parallel, and connect a resistor R49 and a capacitor C48 between the I _SPOS pin P11 and the signal ground , the resistor R49 and the capacitor C48 are connected in parallel, and the _ISPOS pin P11 is connected in series with the fifteenth resistor R30 and then connected to the sources of the first power switch MOSFET D15 and the second power switch MOSFET D16, and the OUTA pin P13 is connected to the signal ground The sixteenth resistor R48 and the seventeenth resistor R44 are connected in series, and a branch is drawn between the sixteenth resistor R48 and the seventeenth resistor R44 to connect the gate of the first power switch MOSFET D15, the OUTB pin The eighteenth resistor R51 and the nineteenth resistor R45 are connected in series between P14 and the signal ground, and a branch is drawn between the eighteenth resistor R51 and the nineteenth resistor R45 to connect the gate of the second power switch MOSFET D16 , the GND pin P15 is connected to the signal ground, and the signal ground and the analog ground are connected through a coupling capacitor C22.

AC input unit: AC input is protected by pre-stage filtering of F2, L5, RP2, C36, L6, C37, C19, and C21, then rectified by BR2, and filtered by post-stage L7 and C38 to provide pulsating DC power to the post-stage.

Power factor adjustment unit: the pulsating direct current provided by the front stage AC input unit, in this unit, through R11, R13, R14 and R35, C39, provides one AC voltage signal to the control chip NCP1652; through R12, R15, R26 and R36, C40 , to provide one AC voltage signal to the control chip NCP1652; the AC voltage signal sampled here enters the control chip and becomes the reference AC voltage signal for adjusting the control system; the current signal is sampled by R50, R30, R49, and R48 and sent to the control chip. Become the reference current signal of the control system; the sampling current signal here is provided by the two interleaved MOSFETs D15 and D16, which realizes current sampling in the full cycle of the system operation, optimizes the sampling current signal, and is a power factor adjustment unit The stable operation under high input voltage provides the basis to ensure that the PF value is not less than 0.9 and the THD value is not greater than 20 when the AC high voltage is input. Realize the green environmental protection used by customers.

Wide voltage start-up unit: the pulsating direct current provided by the front stage AC input unit, in this unit, after the step-down treatment of D4, the maximum voltage to the control chip does not exceed the requirement; it is rectified into direct current by D6; C23 energy storage, R43 current limiting After the voltage is divided, it is sent to the control chip NCP1652 to start the work of the chip and complete the work of the control system in the initial stage; after the initial work of the control system, it is rectified by D7 and D12, R27 limits the current and divides the pressure, C47 and C24 store energy, and the control chip enters normal working condition.

Double FLY-BUCK unit: It is a device that converts the input wide AC voltage into a definite DC voltage to complete the preliminary energy conversion of the product; at the same time, due to the use of the FLY-BUCK conversion scheme, it minimizes the loss caused by the wide input AC voltage range. In the case of high AC input, the pulse width changes greatly, causing the high-end PF value and THD value to change too fast; at the same time, due to the dual FLY-BUCK mode, the high-end PF value and THD value are further optimized. The pulsating direct current provided by the front stage AC input unit, in this unit, the MOSFETs D15 and D16, which are turned on alternately, control T2 and T3 respectively, and transfer energy from the input end to the output end. The turn-on time of D15 and D16 at the input end is It cannot be turned on at the same time in one cycle, and there must be a reliable time interval between the turn-on times of the two MOSFETs to prevent failure and damage to the product; since D15 and D16 maintain a large duty cycle in one working cycle of the control system Time, effectively solve the problem caused by too high single peak value of current sampling and too small duty cycle, the sampled current signal is easier to match and adjust with the voltage sampling signal, resulting in higher PF value and lower THD value ;At the same time, due to the use of double MOSFETs to turn on and transfer energy in an interleaved manner, the energy consumption during the energy transfer period of FLY-BUCK is greatly reduced, thereby improving product efficiency; since the output current is in a continuous state during the entire control system operation, the output filter capacitance can be greatly reduced In extreme cases, the output filter capacitor can even be canceled; since the input current is also in a continuous state, the filter inductance of the AC input unit can greatly reduce the inductance, and can also meet the electromagnetic compatibility requirements. In this unit, U5 and U6 in the negative feedback sampling circuit are the core devices for negative feedback of the output terminal to the input terminal control system to ensure the stability of the output terminal voltage, and the current sampling part is sent to the control system at the same time to control the energy transfer. output power is controlled.

The output constant current source unit, in the example of the present invention, usually uses a constant current source control chip plus peripheral circuits, such as LM3409, etc.; it can also use digital circuits for matching processing to achieve effective control of the output current and meet the requirements of the product on the output current. Control and adjust the requirements to achieve the effect of output constant current and dimming.

To sum up, the present invention discloses a product with wide AC voltage input and adaptable to multiple standard voltages. At the same time, the PF value of the product is effectively improved, the THD value is reduced, and the low cost and high cost of the output filter capacitor and input filter inductance are reduced. indicators, high reliability products. In this product, the bipolar parallel circuit mode is adopted, which brings the advantage that the output current fluctuation is small, and the output filter capacitor can be greatly reduced. For products with low requirements, the output capacitor in the power conversion circuit can be omitted. This is the current It has functions that the LED drive power supply does not have, and it can also greatly reduce the THD value, increase the PF value, and reduce the EMC processing circuit components at the input end (under the condition of ensuring compliance with the FCC15 CLASS2 standard); this is a brand new circuit change. mode, the actual test works fine.

It should be noted that the above-mentioned embodiments are not used to limit the protection scope of the present invention, and equivalent transformations or substitutions made on the basis of the above-mentioned technical solutions all fall within the protection scope of the claims of the present invention. In the claims, the word "comprising" does not exclude the presence of elements not listed in the claims. The use of the words first, second, third, etc. does not indicate any order and these words can be interpreted as names.

Claims (10)

1. An LED constant current driving power supply with wide input voltage range of 120-grade 347VAC is characterized in that: comprises an AC input unit, a double FLY-BUCK unit, a power factor adjusting unit, a wide voltage starting unit and an output constant current source unit, wherein,

the AC input unit is used for providing pulsating direct current and comprises an EMC filtering processing circuit and a bridge full-wave rectifier which are sequentially connected, wherein the input end of the EMC filtering processing circuit is connected with a power supply grid, and the output end of the bridge full-wave rectifier is connected with a double FLY-BUCK unit, a power factor adjusting unit and a wide voltage starting unit;

the output end of the power factor adjusting unit is connected with the double FLY-BUCK unit, the pulsating direct current signal sent by the AC input unit is sampled to obtain a voltage signal, and the voltage signal is compared with a current signal obtained by current sampling provided by the double FLY-BUCK unit to finish matching adjustment of voltage and current waveforms;

the double FLY-BUCK unit comprises a single-stage PFC control circuit, a negative feedback sampling circuit and a double FLY-BUCK power conversion circuit, wherein the negative feedback sampling circuit and the double FLY-BUCK power conversion circuit are connected with the single-stage PFC control circuit, and the double FLY-BUCK power conversion circuit adopts two parallel FLY-BUCK power conversion circuits which work in a staggered mode to realize energy conversion in the whole period under a PWM control mode;

the output end of the wide voltage starting unit is connected with the double FLY-BUCK unit, the pulsating direct current signal sent by the AC input unit is sampled, the pulsating direct current signal is processed and then sent to a single-stage PFC control circuit in the double FLY-BUCK unit, and the energy supply of the control circuit is ensured;

and the input end of the output constant current source unit is connected with the double FLY-BUCK unit, and the output end of the output constant current source unit is connected with the LED product.

2. The 120-volt 347VAC wide input voltage range LED constant current driving power supply as claimed in claim 1, wherein the single-stage PFC control circuit of the dual FLY-BUCK unit employs a single-stage PFC control chip NCP1652 as a controller.

3. The 120-volt 347VAC wide input voltage range LED constant current driving power supply as claimed in claim 2, wherein the dual FLY-BUCK power conversion circuit of the dual FLY-BUCK unit includes a first FLY-BUCK power conversion circuit and a second FLY-BUCK power conversion circuit, an input terminal of the first FLY-BUCK power conversion circuit is connected to the OUTA pin of the controller NCP1652 through a gate of the first power switch MOSFET, an input terminal of the second FLY-BUCK power conversion circuit is connected to the OUTB pin of the controller NCP1652 through a gate of the second power switch MOSFET, and output terminals of the first FLY-BUCK power conversion circuit and the second FLY-BUCK power conversion circuit are connected to an input terminal of the negative feedback sampling circuit and an input terminal of the output constant current source unit; and a resistor is connected between the Rdelay pin of the controller NCP1652 and the signal ground to set the non-overlapping time delay between the OUTA pin and the OUTB pin, so that the first FLY-BUCK power conversion circuit and the second FLY-BUCK power conversion circuit are respectively controlled by the two MOSFETs which are alternately switched on, namely the first power switch tube MOSFET and the second power switch tube MOSFET, and energy is transferred from the input end to the output end.

4. The 120-VAC 347VAC wide input voltage range LED constant current drive power supply of claim 1, wherein the output terminal of the bridge full-wave rectifier of the AC input unit is connected to a post-filter circuit comprising a first inductor and a first capacitor.

5. The 120-VAC 347VAC wide input voltage range LED constant current driving power supply as claimed IN claim 2, wherein the power factor adjusting unit comprises two parallel first and second resistor divider circuits, the first resistor divider circuit is connected to the AC IN pin of the controller NCP1652, and the sine wave rectified and output by the bridge full wave rectifier inputs the information of the line voltage to the multiplier of the controller NCP1652 through the first resistor divider circuit; the second resistance voltage-dividing circuit is connected with the V of the controller NCP1652_FFAnd the rectified and filtered line voltage is input into the controller NCP1652 through a second resistance voltage division circuit.

6. The 120-grade 347VAC wide input voltage range LED constant current driving power supply as claimed in claim 2, wherein the wide voltage starting unit comprises a DC starting circuit of the controller NCP1652 and a starting voltage V_CCThe direct current starting circuit comprises a Schottky diode, a first rectifying diode, a first current-limiting divider resistor and a second capacitor, wherein the anode of the Schottky diode is connected with the anode of the first rectifying diode, and the cathode of the first rectifying diode is connected with the second capacitor and then connected with the second capacitorThe negative electrode of the first rectifying diode is connected with a first current-limiting divider resistor in series and then is connected with the HV pin of the NCP 1652; the starting voltage V_CCThe generating circuit comprises a second rectifying diode, a third rectifying diode, a second current-limiting divider resistor, a third capacitor, a fourth capacitor and a coupling inductor, wherein the anode of the second rectifying diode is connected with the coupling inductor, the cathode of the second rectifying diode is connected with the anode of the third rectifying diode, and the cathode of the third rectifying diode is connected with the Vcc pin of the controller NCP1652 after being connected with the second current-limiting divider resistor in series; one end of the third capacitor is connected between the cathode of the second rectifier diode and the anode of the third rectifier diode, and the other end of the third capacitor is connected with the signal ground; one end of the fourth capacitor is connected between the second current-limiting divider resistor and the Vcc pin, and the other end of the fourth capacitor is connected with a signal ground.

7. The power supply as claimed in claim 1, wherein the EMC filter processing circuit comprises a fuse, a coupling inductor, a resistor, a fifth capacitor, a second inductor, a sixth capacitor, a seventh capacitor and an eighth capacitor, the fuse is connected to the live wire of the ac power grid, the dotted end of the coupling inductor is connected to the live wire and the neutral wire of the ac power grid, the resistor is connected to the dotted end of the coupling inductor in parallel, the fifth capacitor and the sixth capacitor are connected to the two ends of the resistor in parallel, the second inductor is connected between the fifth capacitor and the sixth capacitor, the seventh capacitor is connected between the neutral wire and the zero protection wire in series, and the eighth capacitor is connected between the zero protection wire and the second inductor in series.

8. The 120-valent 347VAC wide input voltage range LED constant current drive power supply as claimed IN claim 5, wherein the first resistor divider circuit comprises a first resistor, a second resistor, a third resistor and a fourth resistor connected IN series IN sequence, a ninth capacitor is connected IN parallel at two ends of the fourth resistor, the end of the fourth resistor is connected to a signal ground, and a branch is LED out between the third resistor and the fourth resistor and connected to an AC IN pin of the controller NCP 1652; the second resistance voltage-dividing circuit comprisesA fifth resistor, a sixth resistor, a seventh resistor and an eighth resistor which are connected in series, wherein a ninth resistor and a tenth capacitor are connected in parallel at two ends of the eighth resistor, the tail end of the eighth resistor is connected with a signal ground, and a branch is led out between the seventh resistor and the eighth resistor and is connected with the V of the controller NCP1652_FFAnd (7) a pin.

9. The power supply as claimed in claim 3, wherein the first FLY-BUCK power conversion circuit comprises a first transformer, a first diode, a tenth resistor, an eleventh capacitor, a first output rectifying diode and a first output capacitor, wherein the positive electrode of the first diode and the primary-side dotted terminal of the first transformer are connected to the drain of the MOSFET, the tenth resistor and the eleventh capacitor are connected in parallel, one end of the tenth resistor is connected to the negative electrode of the first diode, the other end of the tenth resistor is connected to the primary-side dotted terminal of the first transformer, the secondary-side dotted terminal of the first transformer is connected to the positive electrode of the first output rectifying diode, the negative electrode of the first output rectifying diode is connected to the positive electrode of the first output capacitor, the negative electrode of the first output capacitor is connected to the secondary-side dotted terminal of the first transformer and then connected to an analog ground, a branch circuit is led out between the cathode of the first output rectifying diode and the anode of the first output capacitor and serves as a first output end of the double FLY-BUCK unit; the second FLY-BUCK power conversion circuit comprises a second transformer, a second diode, an eleventh resistor, a twelfth capacitor and a second output rectifier diode, wherein the anode of the second diode and the primary side homonymous end of the second transformer are connected with the drain electrode of an MOSFET (metal-oxide-semiconductor field effect transistor), one end of the eleventh resistor is connected with the cathode of the second diode after the eleventh resistor and the twelfth capacitor are connected in parallel, the other end of the eleventh resistor is connected with the primary side synonym end of the second transformer, the secondary side homonymous end of the second transformer is connected with the anode of the second output rectifier diode, the secondary side synonym end of the second transformer is connected to an analog ground, and the cathode of the second output rectifier diode is led out to serve as a second output end of the double FLY-BUCK unit; the primary synonym terminals of the first transformer and the second transformer are connected with the output end of the rear-stage filter circuit of the AC input unit, and the source electrodes of the first power switch tube MOSFET and the second power switch tube MOSFET are connected in series with the twelfth resistor and then connected to the output end of the rear-stage filter circuit of the AC input unit; the negative feedback sampling circuit comprises a current/voltage detection circuit and a photoelectric isolator which are sequentially connected, wherein the first output end and the second output end of the double FLY-BUCK unit are connected with the current/voltage detection circuit on one hand and connected with the output constant current source unit on the other hand, one path of the double-path output end of the photoelectric isolator is connected with an FB pin of the controller NCP1652 through a thirteenth resistor, and the other path of the double-path output end of the photoelectric isolator is connected with the output end of the post-stage filter circuit of the AC input unit.

10. The power supply of claim 2, wherein the external timing capacitor connected to the CT pin of the controller NCP1652 generates a sawtooth wave of 0.2V-0.4V to set the frequency of the oscillator and the gain of the multiplier, and a resistor is connected between the RAMP COMP pin and the signal ground to adjust the amount of slope compensation applied to the current signal to prevent harmonic oscillation; the FB pin is connected with an external error amplifier circuit, the external error amplifier circuit comprises a triode, a fourteenth resistor, a thirteenth capacitor and a fourteenth capacitor, one end of the fourteenth resistor is connected with the FB pin, the other end of the fourteenth resistor is connected with the base electrode of the triode, one end of the thirteenth capacitor is connected with the FB pin, the other end of the thirteenth capacitor is connected with the collector electrode of the triode, the fourteenth capacitor is connected between the base electrode and the emitter electrode of the triode, and the emitter electrode of the triode is connected with a signal ground; a capacitor is connected between the CM pin and the signal ground to filter the output of the internal multiplier, a resistor and a capacitor are sequentially connected between the AC COMP pin and the signal ground in series to serve as the set pole of the AC reference amplifier, the Latch pin is connected with a resistor in series and then connected with the signal ground, the Rdelay pin is connected with a resistor in series and then connected with the signal ground, and I_AVGA resistor and a capacitor are connected between the pin and the signal ground in parallel, I_SPOSA resistor and a capacitor are externally connected between the pin and the signal ground, the resistor and the capacitor are connected in parallel, and I_SPOSThe pin is connected with the source electrodes of the first power switch tube MOSFET and the second power switch tube MOSFET after being connected with the fifteenth resistor in series, and the sixteenth resistor is connected between the OUTA pin and the signal ground in seriesAnd a seventeenth resistor, wherein a branch is led out between the sixteenth resistor and the seventeenth resistor and is connected with the grid of the first power switch tube MOSFET, an eighteenth resistor and a nineteenth resistor are connected between the OUTB pin and the signal ground in series, a branch is led out between the eighteenth resistor and the nineteenth resistor and is connected with the grid of the second power switch tube MOSFET, the GND pin is connected to the signal ground, and the signal ground is connected with the analog ground through a coupling capacitor.