TWI442821B - Led lighting device driven by forward converter using peak current mode - Google Patents

Description

Forward LED converter with peak current mode to drive LED lighting

The invention relates to a forward-mode converter driving LED lamp illumination device in a peak current mode, in particular to an LED lamp set, a forward converter and a control module, which can be modulated by a voltage The modulation circuit changes the reference voltage to control the peak current magnitude to adjust the brightness of the LED light group.

According to the current, there are mainly two ways to control the brightness of the LED lamp group. The first one is to linearly adjust the current of the LED (analog dimming mode); the second is to use the pulse width modulation (PWM) to set the cycle and duty cycle. This is the easiest and most effective way to implement digital dimming. However, the power controller of the LED lamp group is mainly controlled by a constant voltage mode to provide a voltage of about 3.5 to 3.8 V for the LED lighting module. Since the constant voltage system adopts a fixed voltage technology, and the conventional structure increases the current amount when the LED temperature rises, the conventional structure must connect the LED in series with a resistor to fix the voltage, so that the electrical energy is unnecessary. Loss. In addition, when the LED is overheated, especially when the high-power LED is at a high temperature, the semiconductor resistance is lowered, and (V/I=R) causes the current to increase, which may cause the LED to accelerate or thermally collapse. Furthermore, the general LED lamp group dimming circuit adjusts the working time of the LED lamp group to be turned on by the PWM pulse wave of 1K~10K, so the current flowing through the LED lamp group is discontinuous, and thus the LED lamp group will flicker. Since the human eye has a visual persistence, although the average person cannot feel the flashing of the LED light group, it still has a certain degree of influence on the visual acuity.

In order to improve the aforementioned shortcomings, the same industry has developed a power supply for replacing the constant voltage mode to supply the LED lighting module, such as the national new patent publication No. M316577 "LED light source controller", M345931 "with constant current LED lamp with temperature control regulation and invention disclosed in No. 200608122 "Light-emitting diode current controller and method thereof", comprising a main controller, a constant current controller and an LED lighting module, the constant current controller Connected to the output side of the main controller, and the constant current controller has at least one channel connected to the LED lighting module to output a constant current to stabilize the brightness of the LED lighting module, and the LED lighting module can be enabled by an external trigger signal Output different action modes.

Although the conventional structure has an average current output control mode to stabilize the brightness of the LED lighting module; however, the conventional structure adopts a general PWM control circuit instead of a pulse wave control circuit, so the maximum rating of the LED light group cannot be limited. The current, if the instantaneous current is generated and passed through the LED group, the LED group will be burned. Moreover, these conventional structures do not use a switching power converter. Therefore, the current through the LED lamp group is discontinuous, so that the light source emitted by the LED lamp group may flicker, thereby affecting the user's vision.

The reason is that, in view of the above-mentioned conventional structure, the present inventors have actively studied and developed, and finally developed a practical effect.

The main object of the present invention is to provide a forward-mode converter-driven LED lamp illumination device capable of improving the loss of the conventional structure, which is mainly a low-cost integrated circuit UC3845 as a peak current control mode. Group, and through the voltage modulation technology to modulate the reference voltage, thereby regulating the peak current through the LED light group, thereby adjusting the brightness of the LED light source light source, thus having immediate current limiting, current continuous, and controllable peak current The cost of the parts is low, the light source is stable and does not flicker, and the life of the LED light group can be prolonged.

In order to achieve the above effects, the technical means adopted by the present invention comprises an LED lamp group, a forward converter and a control module, and the forward converter comprises an input circuit and a power supply for supplying the LED lamp group. Supplying a circuit, and connecting a switching component and a sensing resistor in the input circuit, the sensing resistor is used for sensing current to be converted into a sensing voltage, and the control module is configured to use the sensing voltage and a reference voltage for limiting the peak current. After the comparison, a pulse signal of a series of duty cycles is generated to trigger the switching element to be turned on and off to control the conduction or the closing of the input circuit, so that the supply circuit can supply a continuous and stable current to the LED lamp group. The control module may be a peak current mode pulse width modulation control integrated circuit UC3843 or an integrated circuit UC3845. The second and eighth pins of the integrated circuit are electrically connected to a voltage modulation circuit for The magnitude of the reference voltage is modulated to control the peak current of the input loop and the supply loop, and the brightness of the LED light group can be adjusted by the voltage modulation circuit.

one. Basic technical features of the present invention

Referring to the first and second figures, the present invention mainly uses a forward current converter (20) of a peak current mode to drive an LED lamp illumination device, and uses a low-cost integrated circuit UC3845 or UC3843 as a peak current. The control module (30), and the voltage modulation technology is used to modulate the reference voltage, thereby adjusting the peak current through the LED light group (10), thereby adjusting the brightness of the LED light group (10), thereby having a time limit Flow action, continuous current, limited peak current, low cost of parts, stable light source without flicker, and extended LED lamp set (10) service life.

Referring to the third and fourth figures, the LED lamp set (10) of the present invention comprises a fixing base (11) and at least one lamp holder (12) provided by a plurality of light emitting diodes (16), and the light emitting diodes The bodies (16) may be electrically connected in series or in parallel. As shown in the first figure, the forward converter (20) includes an input circuit (21) into which a DC power source can be input, and a supply circuit (22) for supplying power required for the LED lamp group (10). and an input circuit (21) connected in series one switching element Q ₁ and a sensing resistor R _1, and a switching element Q ₁ inputted to the switching control circuit (21) is off, the sense resistors R ₁ to sense input circuit The current of (21) is converted into a sensing voltage V _IL , and the control module (30) compares the sensing voltage V _IL with a reference voltage V _REF for defining the peak current to generate a series of duty cycles. the pulse signal to trigger the switching element Q ₁ turned on and off to control the input circuit (21) is turned on or turned off so that the supply circuit (22) is continuous and stable supply of current to the LED lamps (10).

Please refer to the first and second figures. In order to improve the lack of the conventional structure, the present invention uses the inexpensive integrated circuit UC3843 or UC3845 as the control module (30) to simplify the calculation steps and save. The cost of the component is connected to a voltage modulation circuit (40) between the second and eighth pins of the integrated circuit for modulating the magnitude of the reference voltage V _REF to control the input circuit (21). The peak current level with the supply loop (22), whereby the brightness of the LED light group can be adjusted by the voltage modulation circuit (40).

two. Specific embodiment of the present invention 2.1 LED light group

Referring to the third and fourth figures, in order to enable the present invention to adjust the illumination position function of the LED lamp set (10) according to the needs of the user, in a specific embodiment of the LED lamp set (10) of the present invention, the fixing seat ( 11) is a length extending slide rail (11a), the slide rail (1a) is provided with two juxtaposed chutes (110), and a rod body (120) is protruded upward from the lamp holder (12). A fixed shaft (121) is disposed at a top end of the rod body (120), and a conductive portion (13) is respectively disposed at two ends of the fixed shaft (121), and is pivotally disposed on the fixed shaft (121) by two conductive wheels (14) The two conductive portions (13) are formed to form a conductive contact pattern, and the bottom surface of the two sliding slots (110) for the conductive wheel (14) is covered with a conductive material (15), and a conductive material (15) It is electrically connected to the positive terminal of the supply circuit (22), the other conductive material (15) is electrically connected to the ground end of the supply circuit (22), and the other two conductive portions (13) are respectively associated with the LED light group (10). The light-emitting diode (16) is electrically connected, and the supply circuit (22) can continue to supply power to the LED light group (10) when the lamp holder (12) is displaced relative to the slide rail (11a). Moreover, the slide rail (11a) and the fixed shaft (121) are made of an insulating material for separating the polarity of the power source to avoid short circuit of the power source.

Referring to the third to fifth figures, in the above embodiment, in order to provide the conductive wheel (14) with a proper positioning resistance relative to the sliding groove (110), the present invention is provided with a set of two ends at the fixed shaft (121). a damping device (17) for rubbing the side wall of the sliding groove (110) to generate a positioning resistance, and attaching a motor (18) to the rod body (120), the output end of the motor (18) is sleeved a gear (180), the slide rail (11a) is provided with a rack (19) extending in length and meshing with the gear (180), and the motor (18) is electrically connected to a position adjusting means, and the position adjusting means (50) is used The signal of the voltage modulation circuit (40) is taken as a basis for controlling the timing of the operation of the motor (18).

Referring to FIG. 5, the specific embodiment of the position adjustment means (50) includes a signal processing circuit (51), and a control driving circuit (52), the signal processing circuit (51) and the voltage modulation circuit. The circuit (40) is electrically connected to signal the output signal of the voltage modulation circuit (40) to generate a trigger signal, and the control driving circuit (52) can be driven by the trigger signal to drive the motor (18) to operate. In order to control the illumination position of the lamp holder (12), the voltage modulation circuit (40) can be used to modulate the brightness of the LED lamp group (10), and the illumination of the lamp holder (12) can also be controlled. Position to achieve better lighting adjustment. The specific embodiment of the control driving circuit (52) may be a general transistor driving circuit, and the signal processing circuit (51) may be a general comparison circuit.

2.2 forward converter

Referring to Figures 1 and 2, the forward converter (20) of the present invention comprises a transformer (23) comprising a first winding (230), a first winding (230). ) of the second winding (231) is located, and a second winding (231) electrically connected to one side of the third winding (232), a first winding (230) connected to the input sense resistor Q ₁ and R ₁ are electrical switch element circuit (21), a first winding (230) comprising a primary winding (230a) and a winding (230b), by a third winding (232), a first diode D _1, an inductance element L _1, A capacitor C ₁ and a second diode D _{2 are} electrically connected to the supply loop (22), and the second diode D ₂ is connected in reverse parallel between the first diode D ₁ and the inductance element L ₁ . The supply circuit (22) is electrically connected to the first winding (230) to supply a power supply circuit (26) for supplying the power required by the seventh pin V _{CC of the} integrated circuit.

Referring to the first embodiment, in the above specific embodiment, one end of the main winding (230a) and one end of the second winding (231) are respectively electrically connected to a rectifying circuit (25) to allow the pulsating DC generated by the rectifying circuit (25). The power input is electrically connected to the switching element Q ₁ , and the other end of the second winding ( 231 ) is electrically connected to a reversed third diode D ₃ for forming a power return path to consume the transformer ( 23) The leakage inductance energy generated.

Referring to the first and fifth figures, when the switching element Q _{1 is} turned on, the input circuit (21) is turned on, and the first diode D _{1 is} turned on, and the second diode D ₂ is turned off. power supply through the first winding (230) is stored in the core of the transformer (23), and power is transmitted to the third winding (232), the direct conversion of L ₁ and then the power supply via the first diode D ₁ and the inductance element Output to the load terminal of the supply circuit (22) to supply the power required by the LED light group (10).

Referring to the first and fifth figures, when the switching element Q ₁ is turned off, the input circuit (21) is disconnected. At this time, due to the polarity reversal of the first winding (230) of the transformer (23), The first diode D ₁ is turned off, and the second diode D ₂ is turned on, and the power stored by the inductance element L ₁ and the capacitor C ₁ is continuously supplied to the power required by the LED lamp group (10).

2.3 snubber circuit

Referring to the first figure, the first diode D _{1 is} connected across a first snubber circuit (240) composed of a resistor/capacitor RC series circuit to avoid the first diode D ₁ due to the transformer. (23) The stored energy of the leakage inductance of the third winding (232) is destroyed. The second diode D _{2 is} connected across a second buffer circuit (241) composed of an RC circuit to avoid the second diode. The body D ₂ is damaged by the stored electrical energy of the leakage inductance of the third winding (232) of the transformer (23), and the switching element Q _{1 is} connected across a third buffer circuit (242) composed of an RC circuit to avoid the switching element Q _{1 .} The power stored by the leakage inductance of the first winding (230) of the transformer (23) is destroyed, and the stored energy of the leakage inductance generated by the transformer (23) is consumed by the RC circuit.

2.4 Power supply circuit

Referring to the first figure, the power supply circuit (26) of the present invention includes a fourth diode D ₄ , a fifth diode D ₅ and an LC circuit for the purpose of supplying power required for the integrated circuit. (260), the anode of the fourth diode D ₄ is electrically connected to the other end of the main winding (230a), the cathode thereof is electrically connected to the input end of the LC circuit (260), and the anode of the fifth diode D ₅ and the auxiliary winding ( 230b) the other end of the electrical connection, the cathode is electrically connected to the input end of the LC circuit (260), and the input end of the LC circuit (260) is electrically connected to the cathodes of the fourth diode D ₄ and the fifth diode D ₅ respectively The output terminal is electrically connected to the seventh pin of the integrated circuit, and the fourth diode D ₄ and the fifth diode D ₅ are alternately turned on by the switching of the switching element Q _{1 to} make the main winding (230a) and the secondary winding (230b) are capable of charging the LC circuit (260) to supply the power required by the integrated circuit.

2.5 voltage modulation circuit

The voltage modulation circuit (40) of the present invention is provided for adjusting the brightness of the LED lamp group (10), and comprises a first resistor R ₂ and a variable resistor R _T , and the first resistor R _{2 has} one end and an integrated body. pin 8 is electrically connected to the circuit, the other end of which is connected electrically to the variable resistor R _T end, the other end of the variable resistor R is grounded _T, R _{T 3} of modulation and the end of the integrated circuit through a second resistor R The pin 2 is electrically connected, and the second resistor R ₃ is electrically connected to the first pin of the integrated circuit through the third resistor R ₄ , thereby modulating the magnitude of the reference voltage V _REF , thereby controlling the input circuit ( 21 ) and The peak current magnitude of the supply loop (22).

2.6 control module

Referring to the first and second figures, the control module (30) of the present invention comprises an inexpensive integrated circuit UC3843 or UC3845. The integrated circuit UC3845 includes an operational amplifier circuit (31). a comparator (33), a flip-flop (34) and a regulator circuit by a zener diode D ₆ consisting of (32), the operational amplifier circuit (31) comprises an error amplifier (311) and a first The voltage dividing circuit (310), the error operational amplifier (311) and the opposite input end of the comparator (33) are electrically connected to a second voltage dividing circuit (312), and the comparator (33) includes a An inverting input terminal for the reference voltage V _REF input, and a non-inverting input terminal for inputting the sensing voltage V _IL , when the sensing voltage V _IL reaches the potential of the reference voltage V _REF , a high potential is output; flip-flop (34) for lines immediately after receiving the clock signal output from the integrated circuit pin 4 of the oscillator (35) provided by a pulse of the pulse signal of the switching element Q ₁ turns on, when upon receiving the comparator (33) of high potential, the output end of the pulse the switching element Q ₁ circuit.

Referring to the first figure, the first pin of the integrated circuit UC3845 is a compensation terminal, and a resistor R ₄ can be externally connected to compensate the frequency characteristic of the error operational amplifier (311); the second pin is a feedback terminal. Referring to the inverting input terminal of the error operational amplifier (311), the sampling voltage is applied to the inverting input terminal of the error operational amplifier (311), and then compared with the reference voltage of the non-inverting input terminal to output an error control voltage. The third pin of the UC3845 is the non-inverting input of the comparator (33) for connecting the sense resistor R ₁ to form an overcurrent protection circuit; the fourth pin is the timing resistor R ₅ and the capacitor C ₂ The common end of the sum of the sawtooth oscillator; the fifth pin is the ground terminal; the other pin 6 is the output end of the flip-flop (34) for outputting the pulse signal to the base of the switching element Q ₁ ; The 7th pin is the power V _CC terminal. The RC series circuit overlaps the 3rd and 8th pins.

Participation. Operation of a specific embodiment of the present invention 3.1 Operation of the forward converter

Referring to the first and second figures, the forward converter (20) power circuit of the present invention comprises a high frequency transformer (23), a switching element Q ₁ , a capacitor C ₁ , an inductive component L ₁ and a A supply loop (22) consisting of three windings (232) (ie, an output filter). In addition, in addition to isolating noise, the transformer (23) can obtain the required output voltage value by the turns ratio, and the output filter removes the high frequency harmonics, and stores the electric energy when the switching element Q ₁ OFF is supplied with the power supply. To the LED light group (10). The peak current mode control is adopted by the present invention because it has the characteristics of duty cycle current control, instantaneous compensation of input voltage variation, easy stabilization of the feedback circuit, and improvement of load current regulation rate. On the other hand, after the AC mains is passed through a rectifying circuit (25), a pulsating direct current can be obtained, and then the electric energy is converted by the transformer (23) into the supply circuit by the input circuit (21) by the magnetoelectric conversion method (22). among.

3.2 control module

Please refer to the first figure. When the pulse signal enters the flip-flop (34), the flip-flop (34) starts to output the pulse wave of one working cycle in the pulse signal, as shown in the fifth figure. Element Q _{1 is} turned on. When the sense voltage V _{IL does} not reach the potential of the reference voltage V _REF , the comparator (33) in the integrated circuit UC3845 outputs a low potential to the flip-flop (34), so that the flip-flop (34) is maintained. The pulse wave continues to be output at a high potential, and the switching element Q _{1 is} turned on, so that the input circuit (21) is turned on, and the first diode D _{1 is} turned on, and the second diode D ₂ is turned off, and the input power is turned on. through the first winding (230) is stored in the core of the transformer (23), and power is transmitted to the third winding (232), then the output directly to the power supply after the L ₁ via the first diode D ₁ and the inductance element The load terminal of the circuit (22), such as the LED light group (10), can obtain the supply of DC power.

Referring to the first and fifth figures, when the sense voltage V _IL of the comparator (33) in the integrated circuit UC3845 reaches the potential of the reference voltage V _REF , the comparator ( 33 ) outputs a reset signal (ie, High potential) causes the flip-flop (34) to end the pulse of the above duty cycle, as shown in the fifth figure, to make the switching element Q ₁ open, and the input circuit (21) also follows the open circuit, due to the transformer (23) The polarity of the first winding (230) is reversed, so that the first diode D ₁ is turned off, the second diode D2 is turned on, and the LED lamp is continuously supplied by the electric energy stored by the inductance element L ₁ and the capacitor C ₁ . The power supply required by the group (10) can be used to continuously limit the peak current flowing through the LED lamp group (10) by means of a pulse followed by a pulse wave, so as to achieve an instantaneous current limiting effect, and can be stable and continuous. The current is supplied to the LED lamp set (10), so that the light source emitted by the LED lamp set (10) of the present invention does not flicker.

3.3 Adjust the brightness of the LED light source

Please refer to the first and second figures. When the user wants to adjust the brightness of the LED light group (10), only need to adjust the variable resistance R _T knob of the voltage modulation circuit (40) to change the product. The input resistance of the second pin of the body circuit. When the variable resistor R _T adjusts the resistance value, the larger the reference voltage V _REF is output, because the non-inverting input terminal of the error operational amplifier (311) has a connection. The second reference voltage V _{REF is} about 2.5V, so the larger the input voltage of the non-inverting input terminal is, the larger the error value with the second reference voltage V _REF is, so that the output voltage is amplified according to the error value, and The larger the reference voltage V _{REF is} , the later the sensing voltage V _IL sent to the comparator (33) reaches the level of the reference voltage V _REF , so that the pulse width of the duty cycle is widened, and the switching element Q is extended. The on-time of ₁ and the peak current are relatively large, so that the LED lamp group (10) emits a relatively bright light source without changing the pulse wave frequency of the duty cycle.

On the contrary, when the variable resistor R _T adjusts the resistance value smaller, the reference voltage V _REF is smaller, because the non-inverting input terminal of the error operational amplifier (311) is connected with a second reference voltage V _{REF of} about 2.5V. Therefore, the smaller the input voltage of the non-inverting input terminal is, the smaller the error value with the second reference voltage V _REF is, so that the output voltage is amplified according to the error value, and the reference voltage V _{REF is} smaller, so the transmission is performed. The sensing voltage V _{IL of} the comparator (33) reaches the level of the reference voltage V _REF as early as possible, so that the pulse width of the duty cycle is narrowed, and the conduction time of the switching element Q ₁ is shortened, and the peak current is relatively small. In this way, the LED lamp group (10) emits a relatively dark light source under the condition that the pulse wave frequency of the duty cycle is constant, so that the LED lamp group can be adjusted through the voltage modulation circuit (40) ( 10) The brightness of the light source.

Please refer to the sixth figure. Furthermore, the comparison output waveforms of the signals such as the clock signal, the reference voltage V _REF , the sensing voltage V _IL , and the PWM output are as shown in the fourth figure. The size of V _REF can really affect the peak current, so that the light intensity of the LED light group (10) can be more convenient and effective.

Hey. in conclusion

Therefore, with the above technical features, the present invention does have the following features:

1. The invention adopts the low-cost integrated circuit UC3845 as the peak current control module, and modulates the reference voltage through the voltage modulation technology, thereby adjusting the peak current through the LED lamp group, thereby adjusting the LED light source. The brightness and darkness, thus having the characteristics of immediate current limiting, continuous current, limited peak current, low component cost, stable light source and no flashing, and extended LED lamp life.

2. The invention adopts a peak current mode control module, and thus has the characteristics of current control with duty cycle, instantaneous compensation of input voltage variation, easy stable feedback circuit, improved load current adjustment rate and improved dynamic response of output voltage regulation.

The above is only one of the possible embodiments of the present invention, and is not intended to limit the scope of the patents of the present invention, and the equivalent implementations of other changes according to the contents, features and spirits of the following claims are It should be included in the scope of the patent of the present invention. The invention is specifically defined in the structural features of the request item, is not found in the same kind of articles, and has practicality and progress, has met the requirements of the invention patent, and has filed an application according to law, and invites the bureau to approve the patent according to law to maintain the present invention. The legal rights of the applicant.

(10). . . LED light group

(11). . . Fixed seat

(11a). . . Slide rail

(110). . . Chute

(12). . . Lamp holder

(120). . . Rod body

(121). . . Fixed axis

(13). . . Conductive part

(14). . . Conductive wheel

(15). . . Conductive material

(16). . . Light-emitting diode

(17). . . Damping device

(18). . . motor

(180). . . gear

(19). . . rack

(20). . . Forward converter

(twenty one). . . Input loop

(twenty two). . . Supply circuit

(23)‧‧‧Transformers

(230)‧‧‧First winding

(230a)‧‧‧Main winding

(230b)‧‧‧Auxiliary winding

(231)‧‧‧second winding

(232)‧‧‧ Third winding

(240)‧‧‧First snubber circuit

(241)‧‧‧Secondary snubber circuit

(242)‧‧‧ Third buffer circuit

(25)‧‧‧Rectifier circuit

(26)‧‧‧Power supply circuit

(260)‧‧‧LC circuit

(30)‧‧‧Control Module

(31)‧‧‧Operation Amplifier Circuit

(310)‧‧‧First voltage divider circuit

(311)‧‧‧Error Operational Amplifier

(312)‧‧‧Second voltage divider circuit

(32) ‧‧ ‧ voltage regulator circuit

(33)‧‧‧ Comparator

(34) ‧‧‧Fracture

(35)‧‧‧Oscillator

(40) ‧‧‧Voltage modulation circuit

(50) ‧ ‧ position adjustment means

(51)‧‧‧Signal Processing Circuit

(52) ‧‧‧Control drive circuit

C ₁ C ₂ ‧‧‧ capacitor

D ₁ D ₂ D ₃ D ₄ D ₅ D ₆ ‧‧‧ Dipole

L ₁ ‧‧‧inductive components

R ₁ R ₂ R ₃ R ₄ R ₅ R ₆ R ₇ R ₈ R _L ‧‧‧Resistors

R _T ‧‧‧Variable resistor

Q ₁ ‧‧‧Switching elements

The first figure is a circuit diagram of the basic architecture of the present invention.

The second figure is a circuit diagram of the control module of the present invention.

The third figure is a schematic view of the appearance of the LED lamp set of the present invention.

The fourth figure is a partial enlarged view of the portion A of the third figure.

The fifth figure is a schematic diagram of the control block of the basic architecture of the present invention.

The sixth figure is a schematic diagram of various signal output waveforms of the present invention.

(10)‧‧‧LED light group

(16)‧‧‧Lighting diodes

(20)‧‧‧ Forward converter

(21)‧‧‧Input circuit

(22)‧‧‧Supply loop

(23)‧‧‧Transformers

(230)‧‧‧First winding

(230a)‧‧‧Main winding

(230b)‧‧‧Auxiliary winding

(231)‧‧‧second winding

(232)‧‧‧ Third winding

(240)‧‧‧First snubber circuit

(241)‧‧‧Secondary snubber circuit

(242)‧‧‧ Third buffer circuit

(25)‧‧‧Rectifier circuit

(26)‧‧‧Power supply circuit

(260)‧‧‧LC circuit

(30)‧‧‧Control Module

(40) ‧‧‧Voltage modulation circuit

C ₁ C ₂ ‧‧‧ capacitor

D ₁ D ₂ D ₃ D ₄ D ₅ ‧‧‧ Dipole

L ₁ ‧‧‧inductive components

R ₁ R ₂ R ₃ R ₄ R ₅ R ₆ R ₇ R ₈ R _L ‧‧‧Resistors

RT‧‧‧Variable resistor

Q1‧‧‧Switching elements

Claims (9)

A forward-mode converter driving a LED lamp illumination device in a peak current mode, comprising: an LED lamp set comprising a fixing base and at least one lamp holder for a plurality of light-emitting diodes; a forward conversion The device includes an input circuit for inputting a DC power source and a supply circuit for supplying power required for the LED lamp group. The input circuit is connected in series with a switching element and a sensing resistor. Sensing the current of the input circuit and converting it into a sensing voltage, wherein the forward converter further comprises a transformer controlled by the switching element being turned on or off, the transformer comprising a first winding, the first The winding includes a main winding and a pair of windings, the first winding is electrically connected to a power supply circuit, the power supply circuit comprises a fourth diode, a fifth quadrupole and an LC circuit, the fourth pole The anode of the body is electrically connected to the other end of the main winding, and the cathode thereof is electrically connected to the input end of the LC circuit; the anode of the fifth diode is electrically connected to the other end of the auxiliary winding, and the cathode thereof is electrically connected to the input end of the LC circuit The LC battery The input ends are electrically connected to the cathodes of the fourth diode and the fifth diode; and a control module for comparing the sensing voltage with a reference voltage for limiting the peak current After processing, a series of pulse signals of the working cycle are generated to trigger the switching element to be turned on and off to control the conduction or the closing of the input circuit, thereby allowing the supply circuit to supply a continuous and stable current to the LED lamp group. The group is selected from one of a peak current mode pulse width modulation control integrated circuit UC3843 and an integrated circuit UC3845, and a voltage modulation circuit is electrically connected between the second and eighth pins of the integrated circuit. The amplitude of the reference voltage is adjusted to control the peak current of the input loop and the supply loop, thereby adjusting the brightness of the LED light group by the voltage modulation circuit, and the output end of the LC circuit Then, it is electrically connected to the seventh pin of the integrated circuit for supplying power required by the integrated circuit. The forward converter of claim 1 drives the LED lighting device, wherein the fixing seat is provided with a sliding rail, and the sliding rail is provided with two juxtaposed sliding slots, and the lamp holder protrudes upwardly. a fixed shaft is disposed at a top end of the rod body, and a conductive portion is respectively disposed at two ends of the fixed shaft, and is pivotally disposed on the two conductive portions of the fixed shaft by two conductive wheels, wherein the two sliding slots are provided The bottom surface of the conductive wheel is covered with a conductive material, one of the conductive materials is electrically connected to the positive terminal of the supply circuit, and the other conductive material is electrically connected to the ground end of the supply circuit, and the two conductive portions are The LED lamp group is electrically connected. When the lamp holder is displaced relative to the sliding rail, the supply circuit can still supply power to the LED lamp group, and a motor is attached to the rod body, and one output end of the motor is sleeved with a gear The rack is provided with a rack extending in length and meshing with the gear, and the motor is electrically connected to a position adjusting means for capturing the signal of the voltage modulation circuit to control the motor. The basis of the operation timing. The forward converter of claim 2, wherein the sliding rail and the fixed shaft are made of an insulating material, the position adjusting means comprises: a signal processing circuit, and the The voltage modulation circuit is electrically connected to signal the output signal of the voltage modulation circuit to generate a trigger signal; and a control driving circuit that is driven by the trigger signal to drive the motor to operate Control the lighting position of the lamp holder. The forward converter of claim 1 drives the LED lighting device, further comprising a rectifying circuit for converting an AC power source into the pulsating DC power source. The forward converter as claimed in claim 1 , wherein the transformer further comprises a second winding electrically connected to the first winding and a third side on a side of the second winding a winding, the first winding is electrically connected to the switching element and the sensing resistor to form the input circuit, and the third winding, a first diode, an inductive component, a capacitor and a second diode are electrically connected The supply loop, and the second diode system is reversely connected in parallel on the supply loop between the first diode and the inductive component, and one end of the main winding is electrically connected to one end of the second winding. The forward converter of claim 5, wherein the first diode is connected to a first buffer circuit composed of an RC circuit to prevent the first diode from being The stored energy of the leakage inductance of the transformer is damaged. The second diode is connected to a second buffer circuit composed of an RC circuit to prevent the second diode from being damaged by the stored energy of the leakage inductance of the transformer. The switching element is connected across a third buffer circuit composed of an RC circuit to prevent the switching element from being damaged by the stored energy of the leakage inductance of the transformer. The forward converter of claim 5, wherein the other end of the main winding is electrically connected to the switching element, and the other end of the second winding is electrically connected to a third of the reverse direction. The pole body is used to form a path for returning electrical energy to consume leakage inductance energy generated by the transformer. The forward converter as described in claim 1 drives the LED lighting device, The voltage modulation circuit includes a first resistor and a variable resistor. One end of the first resistor is electrically connected to the eighth pin of the integrated circuit, and the other end is electrically connected to one end of the variable resistor. The other end of the variable resistor is grounded, and the variable resistance end is electrically connected to the second pin of the integrated circuit through a second resistor, and the second resistor is transmitted through a third resistor and the integrated circuit. The 1 pin is electrically connected to modulate the magnitude of the reference voltage, thereby controlling the peak current of the input loop and the supply loop. The forward converter of claim 1 drives the LED lighting device, wherein the switching element is a MOSFET transistor, the MOSFET transistor includes a gate G triggered by the pulse signal and respectively connected in series The drain D and the source S on the input loop.