A household LED lighting circuit

Abstract

The present invention discloses a household LED lighting circuit, belonging to the technical field of LED lighting, and solves the problem of low power factor in the prior art. A household LED lighting circuit includes a rectification circuit, a DC-DC converter, an output filter circuit, a main control circuit and an LED lamp group circuit. The rectification circuit is used to convert alternating current into a DC pulsating signal. The DC-DC converter is used to convert the DC pulsating signal into a DC current. The output filter circuit is used to filter out the ripple of the DC current and output the filtered DC current with ripple to the LED lamp group circuit. The LED lamp group circuit is used for lighting. The main control circuit is used to collect the voltage and current signals at the front end of the DC-DC converter and collect the current signal at the rear end of the output filter circuit, so as to make the output current of the output filter circuit constant, and is also used to adjust the input current of the rectification circuit through a PWM signal. The power factor of LED lighting is improved.

Description

Technical Field

[0001] The invention relates to the technical field of LED lighting, and in particular to a household LED lighting circuit. Background Art

[0002] LED is a special diode, which is a current-type nonlinear element. A slight fluctuation in the voltage across the LED will cause the LED current to increase exponentially, resulting in overcurrent damage to the LED. Therefore, current household LED lamp drive circuits all use constant current sources for driving, and each constant current source drives a fixed-power household LED lamp.

[0003] Power factor is an important parameter to measure the quality of power supply of the power grid. When the power supply supplies power to capacitive or inductive loads with sinusoidal AC voltage, the input current still shows the sinusoidal law, but the input current will have a certain lag or lead relative to the sinusoidal input voltage. This phase difference is expressed as φ. In the principle of electrical engineering, the port voltage U and the effective value of the current I of a single-port network are RMS The product of the two is taken as the apparent power. In a sinusoidal AC circuit, since there are resistive energy-consuming elements as well as inductive and capacitive energy-storage elements in the network, the active power is usually smaller than the apparent power. The apparent power needs to be multiplied by a coefficient less than 1 to be equal to the active power. This coefficient can be expressed by the cosine function cosφ of the angle between the sinusoidal input voltage and the sinusoidal input current. This coefficient is called the power factor. Active power refers to the average value of the product of instantaneous current and instantaneous voltage in one cycle, while apparent power is the product of the effective values of current and voltage; the effective value can objectively reflect the working capacity and size of the sinusoidal quantity, while the product of the effective values can reflect the energy capacity that the external network needs to transmit under the normal working state of the power grid; after the AC input power is rectified and filtered, the nonlinear load distorts the current waveform, and the input current is a pulse waveform, containing a large number of harmonic components, which makes the power factor low. At present, the household LED lamp driving circuit adopts passive power factor correction. The power factor after correction is 0.5-0.8, which is low. In addition, household LEDs are sequentially electrically connected in parallel. Each individual LED lamp requires a matching constant current source to drive it, which increases the wiring cost of the household LED lighting system. Summary of the invention

[0004] The purpose of the present invention is to overcome at least one of the above technical deficiencies and to provide a household LED lighting circuit.

[0005] The present invention provides a household LED lighting circuit, which includes a rectification circuit, a DC-DC converter, an output filter circuit, a main control circuit and an LED lamp group circuit. The output end of the rectification circuit is connected to the input end of the DC-DC converter, the output end of the DC-DC converter is connected to the input end of the output filter circuit, and the output end of the output filter circuit is connected to the LED lamp group circuit; the main control circuit is respectively connected to the DC-DC converter and the output filter circuit;

[0006] The rectification circuit is used to convert alternating current into a DC pulsating signal, the DC-DC converter is used to convert the DC pulsating signal into a DC current, the output filter circuit is used to filter out the ripple of the DC current and output the filtered DC current with ripple to the LED lamp group circuit, and the LED lamp group circuit is used for lighting;

[0007] The main control circuit is used to collect the voltage and current signals at the front end of the DC-DC converter and collect the current signal at the rear end of the output filter circuit, so that the output current of the output filter circuit is constant, and is also used to adjust the input current of the rectification circuit through a PWM signal.

[0008] Preferably, the household LED lighting circuit further includes an EMI filter circuit. The input end of the EMI filter circuit is connected to the alternating current, and the output end of the EMI filter circuit is connected to the input end of the rectification circuit; the EMI filter circuit is used to eliminate electromagnetic interference in the alternating current.

[0009] Preferably, the EMI filter circuit includes common mode inductors L1, L2, capacitors CX3, CX4, a varistor RZ, a fuse F and a thermistor NTC. The neutral wire of the alternating current is connected to the first primary end of the common mode inductor L1 through the thermistor NTC, and the live wire of the alternating current is connected to the second primary end of the common mode inductor L1 through the fuse F. The capacitor CX3 and the varistor RZ are connected in parallel between the first primary end and the second primary end of the common mode inductor L1. The capacitor CX4 is connected between the first secondary end and the second secondary end of the common mode inductor L1. The first secondary end and the second secondary end of the common mode inductor L1 are respectively connected to the first primary end and the second primary end of the common mode inductor L2.

[0010] Preferably, the rectification circuit includes capacitors C10, C20, and diodes D10-D40. The capacitors C10, C20 are connected in series between the first secondary end and the second secondary end of the common mode inductor L2; the diodes D10, D20 are connected in series, the diodes D30, D40 are connected in series. The cathode of the diode D10 is connected to the cathode of the diode D30, and the anode of the diode D20 is connected to the anode of the diode D40. The first secondary end and the second secondary end of the common mode inductor L2 are respectively connected between the diodes D30, D40 and between the diodes D10, D20.

[0011] Preferably, the DC-DC converter includes a field effect transistor Q4, diodes D1, D2, D5 and a three-winding transformer T. The three-winding transformer T includes a first primary winding, a second primary winding and a secondary winding. The cathode of the diode D1 is connected to the rectifying circuit, the anode of the diode D1 is connected to the source of the field effect transistor Q4, the drain of the field effect transistor Q4 is grounded, the gate of the field effect transistor Q4 is connected to the main control circuit. The two ends of the first primary winding of the three-winding transformer T are respectively connected to the source of the effect transistor Q4 and the rectifying circuit. One end of the second primary winding of the three-winding transformer T is grounded, and the other end is connected to the DC power supply through the diode D5. The secondary winding of the three-winding transformer T is connected to the output filter circuit.

[0012] Preferably, the DC-DC converter further includes resistors R1-R3 and a capacitor C1. The cathode of the diode D1 is connected to the rectifying circuit through the capacitor C1. The resistor R1 is in parallel with the capacitor C1. The gate of the field effect transistor Q4 is connected to the main control circuit through the resistor R2. The drain of the field effect transistor Q4 is grounded through the resistor R3.

[0013] Preferably, the output filter circuit includes an inductor L4, capacitors E3, E4 and a resistor RS2. The two ends of the capacitor E3 are connected to the two ends of the secondary winding of the three-winding transformer T. One end of the inductor L4 is connected to one end of the capacitor E3. The other end of the capacitor E3 is connected to one end of the resistor RS2. The two ends of the capacitor E4 are respectively connected to the other end of the inductor L4 and the other end of the resistor RS2. The two ends of the capacitor E4 are also connected to the LED lamp group circuit.

[0014] Preferably, the main control circuit includes an ARM chip, an optocoupler U3, capacitors C3-C5, C7, resistors R8, R9, R11. The VEB pin of the ARM chip is grounded through the capacitor C3. The capacitors C3, C4 and the resistor R9 are in parallel. The X pin of the ARM chip is connected to the cathode of the diode D1 through R8. The ISN pin of the ARM chip is connected to the drain of the field effect transistor Q4 through the resistor R3. The QCTRL pin of the ARM chip is connected to the LED lamp group circuit. The ZCD pin of the ARM chip is connected to the second primary winding of the three-winding transformer T. The GND, OUT, VCC pins of the ARM chip are respectively grounded, connected to the gate of the field effect transistor Q4 and the DC power supply. The ICTRL of the ARM chip is connected to the output filter circuit. The 4 pin of the optocoupler U3 is grounded through the capacitor C3. The 3 pin of the optocoupler U3 is grounded. The capacitor C5 is connected between the 1 and 2 pins of the optocoupler U3. The 1 pin of the optocoupler U3 is connected to the output filter circuit through the resistor R11. The 1 pin of the optocoupler U3 is grounded through the capacitor C7.

[0015] Preferably, the LED lamp group circuit includes a plurality of LED lamp groups, each LED lamp group includes a plurality of LED lamps, one LED lamp group corresponds to one field effect transistor, the gate of the field effect transistor is connected to the QCTRL pin of the ARM chip, and the drain and source of the field effect transistor are respectively connected to the anode and cathode of the LED lamp.

[0016] Compared with the prior art, the beneficial effects of the present invention include: the rectifier circuit converts alternating current into a DC pulsating signal, the DC-DC converter converts the DC pulsating signal into a DC current, the output filter circuit filters out the ripple of the DC current, and outputs the filtered DC current with ripple to the LED lamp group circuit for lighting; the main control circuit collects the voltage and current signals at the front end of the DC-DC converter and the current signal at the rear end of the output filter circuit, so that the output current of the output filter circuit is constant, and is also used to adjust the input current of the rectifier circuit through the PWM signal; the power factor of LED lighting is improved. Description of the Drawings

[0017] Figure 1 is a schematic structural diagram of the household LED lighting circuit according to Embodiment 1 of the present invention;

[0018] Figure 2 is the EMI filter circuit according to Embodiment 1 of the present invention;

[0019] Figure 3 is the rectifier circuit according to Embodiment 1 of the present invention;

[0020] Figure 4 is the DC-DC converter according to Embodiment 1 of the present invention;

[0021] Figure 5 is the household LED lighting circuit according to Embodiment 1 of the present invention;

[0022] Figure 6 is the topology diagram of the household LED lighting circuit according to Embodiment 2 of the present invention;

[0023] Figure 7 is a schematic diagram of the series connection mode of the household LED lighting circuit according to Embodiment 2 of the present invention. Detailed Embodiments

[0024] In order to make the objectives, technical solutions and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0025] Embodiment 1

[0026] An embodiment of the present invention provides a household LED lighting circuit, and its structural schematic diagram is as follows Figure 1 As shown, the household LED lighting circuit includes a rectifier circuit, a DC-DC converter, an output filter circuit, a main control circuit, and an LED lamp group circuit. The output end of the rectifier circuit is connected to the input end of the DC-DC converter, the output end of the DC-DC converter is connected to the input end of the output filter circuit, and the output end of the output filter circuit is connected to the LED lamp group circuit; the main control circuit is respectively connected to the DC-DC converter and the output filter circuit;

[0027] The rectifier circuit is used to convert alternating current into a DC pulsating signal, the DC-DC converter is used to convert the DC pulsating signal into a DC current, the output filter circuit is used to filter out the ripple of the DC current and output the filtered DC current with ripple to the LED lamp group circuit, and the LED lamp group circuit is used for lighting;

[0028] The main control circuit is used to collect the voltage and current signals at the front end of the DC-DC converter and the current signal at the rear end of the output filter circuit, so that the output current of the output filter circuit is constant, and is also used to adjust the input current of the rectifier circuit through a PWM signal.

[0029] In a specific embodiment, the main control circuit is connected across the two ends of the DC-DC converter and the output filter circuit to form an output voltage control loop and a primary current control loop. The main control power supply can collect the voltage and current signals at the front end of the DC-DC converter and the current signal at the rear end of the output filter circuit; the voltage and current signals at the front end, together with the main control power supply and the output filter circuit, form a primary current control loop, and the current signal at the rear end of the output filter circuit, together with the main control power supply and the output filter circuit, form an output voltage control loop;

[0030] The output voltage control loop enables the output voltage of the output filter circuit to follow the reference voltage set in the main control circuit, thus ensuring the constancy of the output current; the primary current control loop enables the waveform of the input current of the DC-DC converter to track the instantaneous value change of the input voltage of the DC-DC converter, so that the input current of the driving power supply changes according to a sine wave; the output of the primary current control loop serves as the modulation signal of the PWM, and the PWM output by the main control circuit adjusts the on and off of the MOS tube in the DC-DC converter, making the waveform of the input current approximately the same as the waveform of the AC voltage, and improving the input power factor;

[0031] Preferably, the household LED lighting circuit further includes an EMI filter circuit. The input end of the EMI filter circuit is connected to the alternating current, and the output end of the EMI filter circuit is connected to the input end of the rectifier circuit; the EMI filter circuit is used to eliminate electromagnetic interference in the alternating current;

[0032] In specific implementation, the EMI filtering circuit, such as Figure 2 shown, EMI is electromagnetic interference generated along with the action of voltage and current, and can be conducted along media such as circuits or air. The main function of the EMI filtering circuit is to block the EMI from the power grid to the power supply, and at the same time, it can also play a role in suppressing surges and protecting the power supply;

[0033] Preferably, the EMI filtering circuit includes common-mode inductors L1, L2, capacitors CX3, CX4, varistor RZ, fuse F, and thermistor NTC. The neutral wire of the alternating current is connected to the first primary end of the common-mode inductor L1 through the thermistor NTC, and the live wire of the alternating current is connected to the second primary end of the common-mode inductor L1 through the fuse F. The capacitor CX3 and the varistor RZ are connected in parallel between the first primary end and the second primary end of the common-mode inductor L1. The capacitor CX4 is connected between the first secondary end and the second secondary end of the common-mode inductor L1. The first secondary end and the second secondary end of the common-mode inductor L1 are respectively connected to the first primary end and the second primary end of the common-mode inductor L2;

[0034] In specific implementation, the rectifier circuit is a single-phase bridge uncontrolled rectifier circuit, such as Figure 3 shown, the rectifier circuit can convert alternating current into direct current. Its input is a sine wave, and the output is a half-sine wave;

[0035] Preferably, the rectifier circuit includes capacitors C10, C20, and diodes D10 - D40. The capacitors C10, C20 are connected in series between the first secondary end and the second secondary end of the common-mode inductor L2. The diodes D10, D20 are connected in series, the diodes D30, D40 are connected in series. The cathode of the diode D10 is connected to the cathode of the diode D30, the anode of the diode D20 is connected to the anode of the diode D40. The first secondary end and the second secondary end of the common-mode inductor L2 are respectively connected between the diodes D30, D40 and between the diodes D10, D20;

[0036] Preferably, the DC-DC converter includes a field-effect transistor Q4, diodes D1, D2, D5, and a three-winding transformer T. The three-winding transformer T includes a first primary winding, a second primary winding, and a secondary winding. The cathode of the diode D1 is connected to the rectifier circuit. The anode of the diode D1 is connected to the source of the field-effect transistor Q4. The drain of the field-effect transistor Q4 is grounded. The gate of the field-effect transistor Q4 is connected to the main control circuit. The two ends of the first primary winding of the three-winding transformer T are respectively connected to the source of the field-effect transistor Q4 and the rectifier circuit. One end of the second primary winding of the three-winding transformer T is grounded, and the other end is connected to the DC power supply through the diode D5. The secondary winding of the three-winding transformer T is connected to the output filtering circuit;

[0037] In a specific embodiment, the DC-DC converter is a single-ended flyback DC-DC converter, such as Figure 4 As shown, the DC-DC converter is an isolated DC-DC AC circuit, whose input stage and output stage are isolated from each other, the noise of the input stage will not be transmitted to the output stage, and the output stage has no dangerous voltage to the ground. The DC-DC converter converts direct current into another fixed voltage or adjustable voltage direct current by controlling the on and off of the MOS tube in the circuit;

[0038] Preferably, the DC-DC converter further includes resistors R1-R3 and a capacitor C1, the cathode of the diode D1 is connected to the rectifier circuit via the capacitor C1, the resistor R1 is connected in parallel with the capacitor C1, the gate of the field effect transistor Q4 is connected to the main control circuit via the resistor R2, and the drain of the field effect transistor Q4 is grounded via the resistor R3;

[0039] Preferably, the output filter circuit includes an inductor L4, capacitors E3, E4 and a resistor RS2, the two ends of the capacitor E3 are connected to the two ends of the secondary winding of the three-winding transformer T, one end of the inductor L4 is connected to one end of the capacitor E3, the other end of the capacitor E3 is connected to one end of the resistor RS2, the two ends of the capacitor E4 are respectively connected to the other end of the inductor L4 and the other end of the resistor RS2, and the two ends of the capacitor E4 are also connected to the LED lamp group circuit.

[0040] In a specific embodiment, the output filter circuit includes four components, namely, capacitors E3 and E4, inductor L4 and resistor RS2, and its function is to reduce the AC component in the pulsating DC voltage as much as possible, retain its DC component, reduce the output voltage ripple factor, make the waveform smoother, and stabilize the current flowing through the LED;

[0041] Preferably, the main control circuit includes an ARM chip, an optocoupler U3, capacitors C3-C5, C7, resistors R8, R9, R11. The VEB pin of the ARM chip is grounded through capacitor C3. Capacitors C3, C4 and resistor R9 are in parallel. The X pin of the ARM chip is connected to the cathode of diode D1 through R8. The ISN pin of the ARM chip is connected to the drain of the field effect transistor Q4 through resistor R3. The QCTRL pin of the ARM chip is connected to the LED lamp group circuit. The ZCD pin of the ARM chip is connected to the second primary winding of the three-winding transformer T. The GND, OUT, and VCC pins of the ARM chip are grounded, connected to the gate of the field effect transistor Q4, and the DC power supply respectively. The ICTRL of the ARM chip is connected to the output filter circuit. The 4 pin of the optocoupler U3 is grounded through capacitor C3. The 3 pin of the optocoupler U3 is grounded. Capacitor C5 is connected between the 1 and 2 pins of the optocoupler U3. The 1 pin of the optocoupler U3 is connected to the output filter circuit through resistor R11. The 1 pin of the optocoupler U3 is grounded through capacitor C7;

[0042] Preferably, the LED lamp group circuit includes several LED lamp groups. Each LED lamp group includes several LED lamps. One LED lamp group corresponds to one field effect transistor. The gate of the field effect transistor is connected to the QCTRL pin of the ARM chip. The drain and source of the field effect transistor are connected to the anode and cathode of the LED lamp respectively;

[0043] In a specific embodiment, the household LED lighting circuit, as Figure 5 shown in the figure, the LED lamp group circuit is shown. It can be known that the LED lamp groups in different spaces are connected in series, so that the same constant current source can be used to drive all the LED lamp groups of the household LED lighting circuit. A MOS switch is connected in parallel at both ends of each LED lamp group. The model of the ARM chip is Cotex-M4 (32bit). It collects the input current signal and input voltage signal from the single-phase bridge uncontrollable rectifier filter circuit and the output current signal from the output filter circuit. After being processed by the ARM chip, a PWM control signal is sent to the flyback DC-DC converter to achieve constant current control and power factor correction. The ARM chip is also used to send a control signal to the MOS switch to control the on and off of the LED lamp group. The MOS switch is a circuit constructed based on the principle of controlling the on and off of the source (s) and drain (d) of the MOS transistor by the gate (g) of the MOS transistor. The ARM chip controls respectively. When the MOS switch is turned on, the LED lamp group is turned off. When the MOS switch is turned off, the LED lamp group is turned on.

[0044] Embodiment 2

[0045] An embodiment of the present invention also provides a household LED lighting circuit. The topological diagram of the household LED lighting circuit is as Figure 6 shown, including an EMI filtering circuit, a single-phase bridge uncontrolled rectifier circuit, a flyback DC-DC converter, an output filtering circuit, an LED lamp group circuit, and an ARM control circuit (main control circuit). The EMI filtering circuit, the single-phase bridge uncontrolled rectifier circuit, the flyback DC-DC converter, the output filtering circuit, and the LED lamp group are electrically connected in sequence. The ARM control circuit includes a Cortex-M4 type ARM chip;

[0046] The drive power supply is composed of the EMI filtering circuit, the single-phase bridge uncontrolled rectifier circuit, the flyback DC-DC converter, and the output filtering circuit. The schematic diagram of the series connection mode of the household LED lighting circuit is as Figure 7 shown. After the alternating current of 220V, 50Hz enters the drive power supply, it will first pass through the EMI filtering circuit to eliminate electromagnetic interference, and then enter the single-phase bridge uncontrolled rectifier circuit. Under the action of the unidirectional conductivity of the diode, it is converted into a DC pulsating signal and input into the flyback DC-DC converter. Through the on and off of the MOS tube, the DC pulsating signal is converted into a controllable DC current and enters the output filtering circuit. After filtering out the ripple, it is output to the LED lamp group;

[0047] The Cortex-M4 type ARM chip is connected across both ends of the flyback DC-DC converter to form a feedback circuit, collect the voltage and current signals output by the rectifier circuit and the current signal flowing through the LED lamp group, process them using the Cortex-M4 type ARM chip, output a PWM signal, control the on and off of the flyback DC-DC converter, and make the voltage signal and current signal of the secondary inductor coil of the transformer keep in phase, so as to realize constant current control and power factor correction;

[0048] Multiple LED lamp groups in the LED lamp group circuit are connected in series, so that the current flowing through each LED lamp group is the same. Therefore, they can be driven by the same constant current source. MOS switches are connected in parallel across both ends of each LED lamp group. Taking the enhancement type NMOS as an example, a level signal is sent to the Cortex-M4 type ARM chip through a piezoelectric switch. The Cortex-M4 type ARM chip outputs a high level to the MOS tube, and the NMOS conducts, and the LED lamp group goes out. On the contrary, the Cortex-M4 type ARM chip outputs a low level to the NMOS tube, and the NMOS is pinched off, and the LED lamp group lights up;

[0049] The ARM control circuit is connected across both ends of the single-ended flyback DC-DC converter and the output filter circuit to form an output voltage control loop and a primary current control loop; the output voltage control loop enables the output voltage of the output filter circuit to follow the reference voltage set in the ARM control circuit, thus ensuring a constant output current; the primary current control loop enables the waveform of the input current of the single-ended flyback DC-DC converter to track the instantaneous value change of the input voltage of the single-ended flyback DC-DC converter, so that the input current of the driving power supply changes according to a sine wave; the output of the primary current control loop serves as the modulation signal of the PWM, and the PWM output by the ARM control circuit controls the on and off of the MOS transistor in the single-ended flyback DC-DC converter, making the waveform of the input current approximately the same as the waveform of the AC voltage, and improving the power factor at the input end of the entire circuit.

[0050] It should be noted that the parts not repeatedly described in Embodiment 1 and Embodiment 2 can be borrowed from each other.

[0051] The present invention discloses a household LED lighting circuit. The rectifier circuit converts the alternating current into a DC pulsating signal, the DC-DC converter converts the DC pulsating signal into a DC current, the output filter circuit filters out the ripple of the DC current and outputs the filtered DC current to the LED lamp group circuit for lighting; the main control circuit collects the voltage and current signals at the front end of the DC-DC converter and the current signal at the rear end of the output filter circuit to make the output current of the output filter circuit constant, and is also used to adjust the input current of the rectifier circuit through the PWM signal; the main control circuit, the DC-DC converter and the output filter circuit form an output voltage control loop and a primary current control loop, and the output of the primary current control loop serves as the modulation signal of the PWM. The PWM signal output by the main control circuit adjusts the on and off of the MOS transistor in the DC-DC converter, making the waveform of the input current of the entire circuit approximately the same as the waveform of the AC voltage, thereby improving the power factor of the LED lighting, saving electric energy, and at the same time, improving the power quality of the electric energy, which is beneficial to the safe and stable operation of the power grid; the output voltage control loop enables the output voltage of the output filter circuit to follow the reference voltage set in the main control circuit, ensuring a constant output current. Multiple LED lamp groups can be driven by the same constant current source, which reduces the wiring cost of the household LED lighting system compared with equipping a driving power supply for each single LED lamp.

[0052] The specific embodiments of the present invention described above do not constitute a limitation on the protection scope of the present invention. Any other corresponding changes and deformations made according to the technical concept of the present invention should be included in the protection scope of the claims of the present invention.

Claims

1. A household LED lighting circuit, characterized in that, It includes a rectifier circuit, a DC-DC converter, an output filter circuit, a main control circuit, an LED lamp group circuit and an EMI filter circuit. The output end of the rectifier circuit is connected to the input end of the DC-DC converter. The output end of the DC-DC converter is connected to the input end of the output filter circuit. The output end of the output filter circuit is connected to the LED lamp group circuit. The main control circuit is respectively connected to the DC-DC converter and the output filter circuit. The input end of the EMI filter circuit is connected to the alternating current, and the output end of the EMI filter circuit is connected to the input end of the rectifier circuit; The rectifier circuit is used to convert the alternating current into a DC pulsating signal. The DC-DC converter is used to convert the DC pulsating signal into a DC current. The output filter circuit is used to filter out the ripple of the DC current and output the DC current with filtered ripple to the LED lamp group circuit. The LED lamp group circuit is used for lighting; The EMI filter circuit is used to eliminate the electromagnetic interference in the alternating current; The main control circuit is used to collect the voltage and current signals at the front end of the DC-DC converter and collect the current signal at the rear end of the output filter circuit to make the output current of the output filter circuit constant, and is also used to adjust the input current of the rectifier circuit through the PWM signal; The DC-DC converter includes a field effect transistor Q4, diodes D1, D2, D5 and a three-winding transformer T. The three-winding transformer T includes a first primary winding, a second primary winding and a secondary winding. The cathode of the diode D1 is connected to the rectifier circuit. The anode of the diode D1 is connected to the source of the field effect transistor Q4. The drain of the field effect transistor Q4 is grounded. The gate of the field effect transistor Q4 is connected to the main control circuit. The two ends of the first primary winding of the three-winding transformer T are respectively connected to the source of the effect transistor Q4 and the rectifier circuit. One end of the second primary winding of the three-winding transformer T is grounded, and the other end is connected to the DC power supply through the diode D5. The secondary winding of the three-winding transformer T is connected to the output filter circuit; The main control circuit includes an ARM chip, an optocoupler U3, capacitors C3 - C5, C7, resistors R8, R9, R11. The VEB pin of the ARM chip is grounded through capacitor C3. Capacitors C3, C4 and resistor R9 are in parallel. The X pin of the ARM chip is connected to the cathode of diode D1 through R8. The ISN pin of the ARM chip is connected to the drain of the field - effect transistor Q4 through resistor R3. The QCTRL pin of the ARM chip is connected to the LED lamp group circuit. The ZCD pin of the ARM chip is connected to the second primary winding of the three - winding transformer T. The GND, OUT, VCC pins of the ARM chip are grounded, connected to the gate of the field - effect transistor Q4 and the DC power supply respectively. The ICTRL of the ARM chip is connected to the output filter circuit. The 4 - pin of the optocoupler U3 is grounded through capacitor C3. The 3 - pin of the optocoupler U3 is grounded. Capacitor C5 is connected between the 1 - pin and 2 - pin of the optocoupler U3. The 1 - pin of the optocoupler U3 is connected to the output filter circuit through resistor R11. The 1 - pin of the optocoupler U3 is grounded through capacitor C7; The LED lamp group circuit includes several LED lamp groups. Each LED lamp group includes several LED lamps. One LED lamp group corresponds to one field - effect transistor. The gate of the field - effect transistor is connected to the QCTRL pin of the ARM chip. The drain and source of the field - effect transistor are connected to the anode and cathode of the LED lamp respectively.

2. The household LED lighting circuit according to claim 1, wherein, The EMI filter circuit includes common - mode inductors L1, L2, capacitors CX3, CX4, a varistor RZ, a fuse F and a thermistor NTC. The neutral wire of the alternating current is connected to the first primary terminal of the common - mode inductor L1 through the thermistor NTC. The live wire of the alternating current is connected to the second primary terminal of the common - mode inductor L1 through the fuse F. Capacitor CX3 and varistor RZ are connected in parallel between the first primary terminal and the second primary terminal of the common - mode inductor L1. Capacitor CX4 is connected between the first secondary terminal and the second secondary terminal of the common - mode inductor L1. The first secondary terminal and the second secondary terminal of the common - mode inductor L1 are respectively connected to the first primary terminal and the second primary terminal of the common - mode inductor L2.

3. The household LED lighting circuit according to claim 2, characterized in that, The rectifier circuit includes capacitors C10, C20, diodes D10, D20, D30, D40. Capacitors C10, C20 are connected in series between the first secondary terminal and the second secondary terminal of the common - mode inductor L2. Diodes D10, D20 are in series. Diodes D30, D40 are in series. The cathode of diode D10 is connected to the cathode of diode D30. The anode of diode D20 is connected to the anode of diode D40. The first secondary terminal and the second secondary terminal of the common - mode inductor L2 are respectively connected between diodes D30, D40 and between diodes D10, D20.

4. The household LED lighting circuit according to claim 1, characterized in that, The DC-DC converter further includes resistors R1-R3 and a capacitor C1. The cathode of the diode D1 is connected to the rectification circuit through the capacitor C1. The resistor R1 is connected in parallel with the capacitor C1. The gate of the field effect transistor Q4 is connected to the main control circuit through the resistor R2. The drain of the field effect transistor Q4 is grounded through the resistor R3.

5. The household LED lighting circuit according to claim 1, characterized in that, The output filter circuit includes an inductor L4, capacitors E3, E4, and a resistor RS2. Both ends of the capacitor E3 are connected to both ends of the secondary winding of the three-winding transformer T. One end of the inductor L4 is connected to one end of the capacitor E3. The other end of the capacitor E3 is connected to one end of the resistor RS2. Both ends of the capacitor E4 are respectively connected to the other end of the inductor L4 and the other end of the resistor RS2. Both ends of the capacitor E4 are also connected to the LED lamp group circuit.

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