TWI435527B - Light-emitting diode with dimming function - Google Patents

Description

Light-emitting diode lamp power supply with dimming function

The invention relates to a power supply for a light-emitting diode lamp, in particular to a light-emitting diode lamp power supply capable of providing a dimming function under a single-stage power conversion circuit (AC/DC) architecture.

As shown in the third figure, there is a known power supply for a light-emitting diode lamp, which comprises an AC/DC power converter (70) and a DC-DC converter ( 80); wherein: the AC/DC power converter (70) includes a transformer T. The primary side of the transformer T is provided with a filter circuit (71), a rectifier circuit (72), a power switch (73), and a pulse width. The modulation controller (74), the AC mains is filtered and rectified into a DC power supply via a filter circuit (71) and a rectifier circuit (72), and then sent to the primary side of the transformer T, and the primary side of the transformer T is connected to the power switch (73). The secondary side is connected to the DC-DC converter (80) through an output circuit (75), and the power switch (73) is controlled by the pulse width modulation controller (74) to determine the primary side of the transformer T. The turn-on period, so that the output voltage (75) of the secondary side outputs a DC voltage, and the output current of the output circuit (75) is fed back to the pulse width modulation controller (74) by the pulse width modulation controller ( 74) Adjust the switching period of the power switch (73) to stabilize the output voltage.

Since the output brightness of the LED lamp is related to the current intensity of the operating power supply, it is necessary to further stabilize the DC-to-DC converter (80). The DC-to-DC converter (80) includes a control unit (81) with a built-in pulse width modulation (PWM) controller for DC-to-DC conversion; and the aforementioned control unit (81) further provides a dimming control pin. (DIM), in order to accept the PWM mode dimming signal sent by externally, through the control of the internal logic gate, change the current output to the LED lamp to adjust the brightness of the LED lamp.

The power supply of the above-mentioned light-emitting diode lamp provides functions such as AC mains power supply and dimming. In order to meet the foregoing functions, a two-stage circuit must be used, the first stage is used for AC-DC conversion, and the latter stage is used for steady current processing and dimming function, but Both-stage circuits have energy losses, and there is room for review, both in terms of overall efficiency and cost.

Please also refer to the fourth figure, which discloses another power supply device for a light-emitting diode lamp, which can achieve a stable output current under a single-stage architecture. The light-emitting diode lamp power supply includes a transformer T. The primary side of the transformer T is provided with a filter circuit (91), a rectifier circuit (92), a power switch (93), a power factor correction circuit (94) and a control unit of a built-in pulse width modulation controller ( 90) After the AC mains is filtered and rectified and power factor corrected, the DC power is sent to the primary side of the transformer T, and the primary side of the transformer T is connected to the power switch (93), and the secondary side is transmitted through an output circuit (95). ) is connected to a light-emitting diode lamp (not shown), and the power switch (93) is controlled by the control unit (90) to determine the conduction period of the primary side of the transformer T, thereby being outputted by the secondary side (95). The output DC voltage is outputted to the control unit (90) through a steady current regulator (CC/CV) controller (96) and an optocoupler (97). The unit (90) adjusts the switching period of the power switch (93) to stabilize the output voltage and power .

The output circuit (95) of the power supply of the light-emitting diode lamp is fed back to the control unit (90) through the steady-state voltage regulator controller (96), so that the control unit (90) adjusts the switching period of the power switch (93). The voltage regulation and current function is provided under the single-stage conversion circuit architecture. However, these power supplies still do not have a dimming function, and cannot meet the requirements that the current LED lamp is gradually required to have a dimming function.

It can be seen from the above that there are still some applications for the power supply of the LED lamp, and it is still necessary to further review and seek a feasible solution.

Therefore, the main object of the present invention is to provide a power supply for a light-emitting diode lamp with a dimming function, which can achieve dimming and steady current under the structure of a single-stage power conversion circuit (AC/DC).

The main technical means for achieving the foregoing objective is that the foregoing power supply device for the light-emitting diode lamp with dimming function comprises: an AC-DC power conversion module, which is mainly provided with a filter circuit on the primary side of a transformer. a rectifier circuit, a power switch, a power factor correction circuit, and a control unit of a built-in pulse width modulation controller; wherein the power on relationship is controlled by the control unit to determine a conduction period of the primary side of the transformer; The output circuit is connected to the feedback end of the control unit through a steady current regulator controller; the dimming module has a dimming signal input end and a compensating voltage output end. The compensation voltage output end is connected to the feedback current input end of the steady current voltage regulator controller; the AC/DC power conversion module is connected with an LED output lamp at an output end of the output circuit thereof, the dimming module The dimming signal input end is connected to a dimmer to receive the PWM form dimming signal input by the dimmer, and when the dimming module receives a dimming signal, The voltage output terminal generates a corresponding compensation voltage, and is applied to the steady current regulator controller feedback current input terminal, thereby changing the feedback current obtained by the steady current regulator controller from the output circuit, and the feedback current is The control unit that is fed back to the AC/DC power conversion module immediately adjusts the on-period of the power switch to adjust the output current of the output circuit output to the LED lamp. Since the brightness of the LED lamp is related to the current intensity, The output current of the AC/DC power conversion module is changed, and the brightness of the LED lamp is also changed at the same time. Therefore, the invention only adopts a single-stage power conversion circuit architecture, that is, the purpose of achieving steady current and dimming can be achieved. Overall efficiency has increased significantly.

As shown in the first figure, the present invention includes an AC/DC power conversion module (10) and a dimming module (20). The output end of the AC/DC power conversion module (10) is coupled to a light emitting diode. The lamp (30) is connected, and the input end of the dimming module (20) is connected to a polarity-free dimmer (40) to receive the PWM form dimming signal input by the dimmer; wherein: the AC/DC power supply The conversion module (10) is mainly provided with a filter circuit (11), a rectifier circuit (12), a power switch (13), a power factor correction circuit (14) and a built-in side on a primary side of a transformer T. a control unit (15) of the pulse width modulation controller; wherein the power switch (13) is controlled by the control unit (15) to determine a conduction period of the primary side of the transformer T; and an output circuit is provided on the secondary side of the transformer T (16), the output end of the output circuit (16) is connected with a plurality of resistors R _SENSE , R2 , R3 R R5 , wherein the resistors R _SENSE and R2 form an output current detection loop, and the output node of the resistor R2 is connected. To a steady current regulator controller (17).

The steady current regulator controller (17) has two sets of OP1 and OP2, respectively performing steady current voltage stabilization control, wherein an OP2 system performs voltage regulation control, and a positive terminal input is connected with a sigma diode to provide a The reference voltage of 2.5V, the negative terminal passes through the voltage dividing resistor R7, R8 detects an output voltage Vout from the resistor R3 at the output end of the output circuit (16); and the other OP1 performs steady current control, and the positive terminal is a reference In the present embodiment, the reference voltage Vref' on the reference voltage terminal is supplied by the reference voltage Vref of 2.5V provided by the positive terminal of the OP2, and is divided by the resistors R4 and R5, and the negative terminal thereof constitutes a feedback current. The input terminal (A) is connected to the output current detecting circuit; in addition, the outputs of the two OP1 and OP2 are commonly connected to the feedback terminal of the control unit (15) through an optical coupler (18), thereby The output current and output voltage detected from the output circuit (16) are fed back to the control unit (15) to regulate the output current/voltage to achieve steady current and voltage regulation.

The dimming module (20) has a dimming signal input end (23) and a compensating voltage output end (24), wherein the dimming signal input end (23) is coupled to an external polarity-free dimmer (40). ) is connected to receive a dimming signal in the form of a pulse width modulation (PWM) fed by the polarity-free dimmer (40), and the compensation voltage output terminal (24) is connected to the steady current regulator controller (17) In the feedback current input terminal (A), in the embodiment, the compensation voltage VC6 generated by the compensation voltage output terminal (24) is transmitted through the voltage dividing resistor R1, R2 and then applied to the steady current regulator controller ( 17) is fed back to the current input terminal (A), whereby the dimming signal sent by the polarity-free dimmer (40) generates a corresponding compensation voltage VC6, so that the control unit (15) adjusts the output circuit (16). The output current is used to change the brightness of the light-emitting diode lamp, thereby achieving the purpose of dimming.

The specific configuration and working principle of the aforementioned dimming module (20) are further described in detail. In this embodiment, the dimming module (20) includes a rectifying circuit (21), a driving circuit (22), and a charging and discharging capacitor C6, the rectifying circuit (21) is composed of a bridge rectifier, the input end of which is connected to the non-polarity dimmer (40), and the output end thereof is connected to the driving circuit (22), in this embodiment The driving power terminal P of the driving circuit (22) and the positive terminal of one of the OP2 voltage regulator controllers (17) obtain a working power of 2.5V, thereby eliminating the need to provide an auxiliary power source. The driving circuit (22) is composed of an NPN transistor Q18 and a PNP transistor Q17. The bases of the two transistors Q18 and Q17 are respectively connected to the output end of the rectifier circuit (21) through a resistor R45 and R53, NPN. The connection node of the transistor Q18 emitter and the PNP transistor Q17 collector is connected to the charging and discharging capacitor C6, and the NPN transistor Q18 and the PNP transistor Q17 are respectively operated in the saturation region and the cutoff region to determine the charging and discharging capacitance C6. During charging and discharging, when the NPN transistor Q18 is turned on, the capacitor voltage VC6 of the charging and discharging capacitor C6 rises, and when the PNP transistor Q17 is turned on, the capacitor voltage VC6 of the charging and discharging capacitor C6 decreases, whereby the charging and discharging capacitor C6 The capacitor voltage VC6 can be determined by the duty width of the PWM dimming signal, and the average value is 0~2.5V (ignoring the VCE of BJT).

When the PWM dimming signal has Duty=0, that is, the dimming function is not performed, the steady current regulator controller (17) returns the voltage on the current input terminal (A) (V _SENSE ) by the output current I ₀ * resistor R _SENSE determines that since the OP1 system of the steady current regulator controller (17) is connected to the feedback current input terminal (A) with a negative terminal, the positive terminal thereof obtains a reference voltage Vref through the voltage dividing resistors R4 and R5. Since the steady state value of the negative terminal of OP1 must be equal to the reference voltage of the positive terminal, the function of stabilizing current is achieved.

When the duty of the PWM dimming signal is not equal to 0, the dimming function will be performed. The positive terminal of the OP1 that performs the stable current still obtains the reference voltage Vref' through the voltage dividing resistors R4 and R5, due to the steady state of the negative voltage V _SENSE of the OP1. The value must be equal to the reference voltage Vref' of the positive terminal, and the voltage V _SENSE of the negative terminal of the original OP1 is Io*R _SENSE , but after the PWM dimming signal is added, the driving circuit (22) is turned on to charge and discharge the charging and discharging capacitor C6, so there is a The voltage (VC6(R2/(R1+R2)) is applied to the negative terminal of OP1. At this time, the negative voltage of OP1 is

V' _SENSE = VC6(R2/(R1+R2))+Io*R _SENSE and V' _SENSE >V _SENSE .

Under the foregoing conditions, the signal fed back to the control unit (15) by the steady current regulator controller (17) will cause the control unit (15) to judge that the output current Io is too high, thereby lowering the output circuit (16). The output current (by changing the output voltage), and then adjust the brightness of the LED (30), because the compensation voltage value (ie VC6) output by the dimming module (20) is based on the period of the PWM dimming signal However, if the output compensation voltage is different, the LED (30) can be adjusted to different brightness. With the foregoing design, the present invention can have both steady current and dimming functions under a single-stage AC/DC power conversion circuit architecture.

Furthermore, in the foregoing embodiment, the operating voltage of the driving circuit (22) in the dimming module (20) and the reference voltage Vref' of the steady current using the OP1 in the steady-state voltage regulator controller (17) are all from steady flow stability. In the voltage controller (17), the voltage regulator is supplied with the reference voltage terminal of the OP2. If the condition is not required, the auxiliary power supply is additionally provided based on the requirements of the working power supply and the reference voltage, so that the cost is reduced and the circuit configuration is simplified. . In addition, when the reference voltage supplied by the reference voltage terminal of the voltage regulator OP2 in the steady current regulator controller (17) is low, the reference voltage Vref can be supplied to the OP1 without dividing the resistor R4 and R5; On the one hand, the compensation voltage of the compensation voltage output terminal (24) can also be directly applied to the feedback current input terminal (A) of the steady current regulator controller (17) without being divided by the resistors R1 and R2.

Please refer to the second embodiment, which is another preferred embodiment of the present invention. The overall structure is substantially the same as that of the previous embodiment, except that the compensation voltage output terminal of the dimming module (20) is further connected in parallel. A type of polar dimmer (50) is provided. In this way, the power supply of the LED lamp of the present invention can be analogized and can be analogized except that the dimming signal can be dimmed. The dimming signal of the polarity performs dimming.

(10). . . AC and DC power conversion module

(11). . . Filter circuit

(12). . . Rectifier circuit

(13). . . Power switch

(14). . . Power factor correction circuit

(15). . . control unit

(16). . . Output circuit

(17). . . Steady current regulator

(18). . . Optocoupler

(20). . . Dimming module

(twenty one). . . Rectifier circuit

(twenty two). . . Drive circuit

(twenty three). . . Dimming signal input

(twenty four). . . Compensation voltage output

(30). . . Light-emitting diode lamp

(40). . . Non-polar dimmer

(50). . . Analog type polar dimmer

(70). . . AC and DC power converter

(71). . . Filter circuit

(72). . . Rectifier circuit

(73). . . Power switch

(74). . . Pulse width modulation controller

(75). . . Output circuit

(80). . . DC to DC converter

(81). . . control unit

(90). . . control unit

(91). . . Filter circuit

(92). . . Rectifier circuit

(93). . . Power switch

(94). . . Power factor correction circuit

(95). . . Output circuit

(96). . . Steady current regulator

(97). . . Optocoupler

First Figure: A detailed circuit diagram of a preferred embodiment of the present invention.

Second Figure: A detailed circuit diagram of still another preferred embodiment of the present invention.

Figure 3: Detailed circuit diagram of a two-stage LED power supply.

Figure 4: Detailed circuit diagram of the power supply for single-stage LED light fixtures.

(10). . . AC and DC power conversion module

(11). . . Filter circuit

(12). . . Rectifier circuit

(13). . . Power switch

(14). . . Power factor correction circuit

(15). . . control unit

(16). . . Output circuit

(17). . . Steady current regulator

(18). . . Optocoupler

(20). . . Dimming module

(twenty one). . . Rectifier circuit

(twenty two). . . Drive circuit

(twenty three). . . Dimming signal input

(twenty four). . . Compensation voltage output

(30). . . Light-emitting diode lamp

(40). . . Non-polar dimmer

Claims (9)

A power supply device for a light-emitting diode lamp with dimming function comprises: an AC-DC power conversion module, which is mainly provided with a filter circuit, a rectifier circuit, a power switch and a power on a primary side of a transformer. a factor correction circuit and a control unit of a built-in pulse width modulation controller; wherein the power on relationship is controlled by the control unit to determine a conduction period of the primary side of the transformer; and the secondary side of the transformer is provided with an output circuit, the output circuit And a steady current regulator controller is connected to the feedback terminal of the control unit; a dimming module has a dimming signal input end and a compensating voltage output end, and the dimming signal input end is used to receive a pulse The wide-tuning type of dimming signal is connected to the feedback current input end of the steady current regulator controller; thereby, the dimming module is generated according to the input pulse width modulated dimming signal A corresponding compensation voltage is sent from the compensation voltage output terminal to the steady current regulator controller, so that the control unit adjusts the output current of the output circuit to achieve the purpose of dimming. For example, in the power supply device of the light-emitting diode lamp with the dimming function described in claim 1, the output end of the output circuit is respectively connected with a plurality of resistors to respectively form an output current detection circuit and an output voltage detection. The circuit is connected to the steady current regulator controller respectively; the steady current regulator controller has two sets of OP1 and OP2, respectively performing steady current voltage stabilization control, wherein an OP2 system performs voltage regulation control, and its positive input connection a diverger diode to provide a reference voltage, the negative terminal of which detects an output voltage from the output of the output circuit through a group of piezoresistors; Another OP1 system performs steady current control, and its positive terminal is a reference voltage terminal, and its negative terminal constitutes a feedback current input terminal, and is connected with the output current detection circuit; the outputs of the two OP1 and OP2 are commonly transmitted through An optical coupler is coupled to the feedback terminal of the control unit. The dimming module includes a rectifying circuit, a driving circuit and a charging and discharging capacitor, and the input end of the rectifying circuit is coupled to the power supply device for the dimming diode lamp with dimming function according to the second aspect of the patent application. A non-polar dimmer is connected, and an output end thereof is connected to the driving circuit, and the output end of the driving circuit is connected with the charging and discharging capacitor to control charging and discharging. The power supply device for a light-emitting diode lamp with a dimming function according to claim 3, wherein the driving circuit is composed of an NPN transistor and a PNP transistor, and the bases of the two transistors respectively pass through a resistor. Connected to the output of the rectifier circuit, the connection node of the NPN transistor emitter and the PNP transistor collector is connected to the charge and discharge capacitor. The power supply device for a light-emitting diode lamp with dimming function according to any one of claims 2 to 4, wherein the power supply end of the driving circuit of the dimming module and an OP2 in the steady current voltage regulator controller are provided. The positive terminal is connected to obtain the working power; the other OP1 positive terminal in the steady current regulator controller obtains the reference voltage from the positive terminal of the aforementioned OP2. For example, in the power supply device of the light-emitting diode lamp with the dimming function described in claim 5, the other OP1 positive end of the steady-state voltage regulator controller is divided by the positive end of the OP2 through a group of piezoresistors. After the voltage is taken, the reference voltage is obtained. For example, in the power supply device of the light-emitting diode lamp with the dimming function described in claim 5, the output end of the driving circuit of the dimming module is connected to the steady-state voltage regulator controller through a group of piezoresistors. Feedback current input. For example, in the power supply device of the light-emitting diode lamp with the dimming function described in claim 7, the rectifier circuit of the dimming module is composed of a bridge rectifier. The power supply device for a light-emitting diode lamp with dimming function according to any one of claims 1 to 4, wherein the offset voltage output end of the dimming module is further provided with an analog type in parallel. Dimmer connection.