Current control circuit and control method for a multi-primary-color LED lamp

Abstract

The present invention discloses a current control circuit and a control method for a multi-primary-color LED lamp. The current control circuit includes a multi-channel current detection module, a multi-channel constant current driving module, and a driving control module. The multi-channel current detection module includes a multi-channel current conversion and amplification unit and a current sampling and control unit. The multi-channel current conversion and amplification unit converts multi-channel current signals into multi-channel voltage signals and amplifies them respectively. The current sampling and control unit collects the multi-channel voltage signals respectively and converts them into current values, and sends them to the driving control module. The driving control module internally stores the functional relationship between the current of each primary-color LED loop and the duty cycle of the corresponding PWM wave, the target current of each loop under a specific light color of the multi-primary-color LED lamp, and the PID control algorithm program, and controls the current of each primary-color LED loop of the multi-channel constant current driving module to track the set target current. The present invention can effectively reduce the color difference between lamps caused by the non-uniformity of the driving current among multi-primary-color LED lamps of the same batch.

Description

Technical Field

[0001] The present invention relates to the technical field of semiconductor lighting, and in particular to a current control circuit and a control method for a multi-primary-color LED lamp. Background Art

[0002] Since multi-primary-color LED lamps can adjust different lighting modes according to different usage scenarios. For example, when a warm atmosphere is needed, it can be adjusted to a low color temperature mode; when one needs to concentrate on work, it can be adjusted to a high color temperature. However, in currently mass-produced LED lamps, due to the superposition of factors such as the delay in the internal circuit of the constant current driving chip, the difference in input voltage, the difference in the resistance value of the sampling resistor, and the decrease in the LED conduction voltage caused by the temperature rise after the LED is lit, the current output by the constant current driving chip is not constant. This results in that when the same batch of multi-primary-color LED light sources are driven by the same batch of multi-channel constant current driving power supplies, the loop currents of the same-color LEDs in different lamps are not exactly the same, the spectra of different multi-primary-color LED lamps vary greatly, and the light colors of different multi-primary-color LED lamps will also show significant differences under the same lighting mode. When the same batch of multi-primary-color LED lamps are used in the same lighting place, the light color differences between different lamps will bring an unpleasant viewing experience and even negative emotions. Summary of the Invention

[0003] In view of the above problems, the present invention provides a current control circuit and a control method for a multi-primary-color LED lamp, aiming to solve the problem of light color differences caused by the non-uniformity of power supplies among different multi-primary-color LED lamps in production.

[0004] The present invention specifically adopts the following technical solutions to achieve the above objectives:

[0005] A current control circuit for a multi-primary-color LED lamp, comprising a multi-channel current detection module, a multi-channel constant current drive module, a drive control module, and a multi-primary-color LED light source. The multi-primary-color LED light source is composed of multiple single-primary-color LED light sources. The multi-channel current detection module is composed of a multi-channel current conversion and amplification unit and a current sampling and control unit. The drive control module is connected to and controls the multi-channel constant current drive module to output adjustable multi-channel LED loop currents. The multi-channel current conversion and amplification unit converts the current signals of each single-primary-color LED loop into voltage signals and amplifies them. Each voltage signal is collected by the corresponding current sampling and control unit and converted into current information, which is sent to the drive control module. The drive control module internally sets the functional relationship between the current and the PWM wave duty cycle, and also sets the target current of each single-primary-color LED loop under a specific light color and the PID control algorithm program corresponding to each primary-color LED, so as to control the current of each primary-color LED loop of the multi-channel constant current drive module to track the set target current, thereby effectively reducing the difference in the current of the same primary-color LED loop between different multi-primary-color LED lamps, and further reducing the light color difference between different multi-primary-color LED lamps in the same lighting mode.

[0006] Further, the multi-channel current conversion and amplification unit includes multiple current conversion and amplification subunits. Each current conversion and amplification subunit includes a current sampling resistor, a first operational amplifier circuit, a filter circuit, and a second operational amplifier circuit. The resistance value of the current sampling resistor is in the milliohm level, with a low temperature drift coefficient and high precision. Its two ends are connected in parallel to the in-phase and anti-phase ends of the first operational amplifier circuit and are connected in series with the single-primary-color LED light source in the corresponding LED loop. The first operational amplifier circuit plays a role in current conversion and amplification, adopts a differential amplification structure, linearly amplifies the potential difference across the current sampling resistor, and the output end is connected to the input end of the filter circuit. The filter circuit adopts an RC second-order filter circuit. The output end of the filter circuit is connected to the input end of the second operational amplifier circuit. The second operational amplifier circuit follows the input voltage and plays an isolation role.

[0007] Further, the current sampling and control unit of the current control circuit for the multi-primary-color LED lamp internally is provided with a multi-channel ADC (analog-to-digital converter). The input ends of the ADC channels corresponding to each single-primary-color LED loop are respectively connected to the output ends of the second operational amplifier circuits of the corresponding current conversion and amplification subunits. The signal sending end of the current sampling and control unit is connected to the signal receiving end of the drive control module.

[0008] Further, the driving control module of the current control circuit of the multi-primary color LED lamp includes a storage unit, an arithmetic control unit, and multiple PWM wave output channels; the storage unit stores the functional relationship between the current of each single-primary color LED loop and the duty cycle of the corresponding PWM wave, and also stores the target current values of each single-primary color LED loop under a specific light color and the PID control algorithm program corresponding to each primary color LED; the arithmetic control unit is used to decode the signal sent by the current sampling control unit to obtain the actual current values of each single-primary color LED loop, and control the duty cycle of the PWM wave of each single-primary color LED loop using the PID algorithm according to the error between the actual current and the target current of each single-primary color LED loop. The PWM wave output channels corresponding to each single-primary color LED loop are respectively connected to the signal control ends of the single-primary color LED loops corresponding to the multi-channel constant current driving module.

[0009] The present invention also provides a control method for the current control circuit of a multi-primary color LED lamp, specifically including the following steps:

[0010] S1: Test and record the duty cycle Dutyi of the PWM wave output from the driving control module to each primary color LED loop driven by the multi-channel constant current driving module and the driving current Ii data of the corresponding primary color LED loop, where i represents the i-th primary color. Use mathematical calculation software to perform polynomial fitting on Ii and Dutyi to obtain the functional relationship Dutyi = ai + bi * Ii.

[0011] Among them, ai and bi are the fitting coefficients of the current and duty cycle corresponding to the i-th primary color LED loop respectively.

[0012] S2: Store the target current Ii_Goal of each primary color LED loop under a specific light color, the functional relationship obtained in step S1, and the PID control algorithm program in the driving control module.

[0013] S3: According to the functional relationship obtained in step S1, obtain the duty cycle Dutyi_Init of the PWM wave corresponding to the target current Ii_Goal of each primary color LED loop. When the multi-primary color LED lamp is turned on, output the PWM wave with a duty cycle of Dutyi_Init to the control end corresponding to the i-th primary color LED in the multi-channel constant current driving module in sequence.

[0014] S4: The current sampling control unit collects the actual current Ii_Actual of each primary color LED in real time, and sends the actual current values Ii_Actual of each primary color LED loop to the drive control module according to a specific coding method, where the specific coding method is one of multiple coding protocols such as serial communication protocol, SPI bus, Bluetooth, WIFI, IIC bus, RS485, and DMX512. The drive control module decodes and calculates the difference Ii_ERROR between the target current Ii_Goal and the actual current Ii_Actual of each primary color LED. The drive control module uses the PID control algorithm for Ii_ERROR to obtain the adjusted current Ii_New of each primary color LED loop in the multi-primary color LED lamp, and obtains the duty cycle Dutyi_New of the PWM wave corresponding to each primary color LED loop that needs to be adjusted in real time through the functional relationship obtained in step S1. The PWM wave corresponding to the i-th primary color LED loop after adjusting the duty cycle is output to the control end of the i-th primary color LED loop of the multi-channel constant current drive module.

[0015] S5: Step S4 is looped, and a dynamic adjustment time of not less than 10 minutes for step S4 is preset. After the dynamic adjustment time, the light sources of each primary color LED in the multi-primary color LED lamp tend to be thermally stable, and the currents of each primary color LED loop also tend to be stable after the adjustment, and are basically close to the target current value Ii_Goal in step S2.

[0016] S6: Based on the current control circuit of the multi-primary color LED lamp, the control method from step S2 to step S5 above is adopted for different multi-primary color LED lamps of the same model to track the target current of each single primary color LED loop in real time.

[0017] The beneficial effects of the present invention are that the current control circuit and its control method of the multi-primary color LED lamp provided by the present invention can collect the currents of each color LED string loop with high precision, and can quickly control the currents of each color LED string loop to reach the target current under a specific light color, greatly improving the light color difference caused by the inconsistency of the currents of the same color LED loops between different multi-primary color LED lamps, and enhancing the lighting experience of the multi-primary color LED lamp. Description of the Drawings

[0018] Figure 1 is the internal module system block diagram of a traditional multi-primary color LED lamp without current control;

[0019] Figure 2 is the connection schematic diagram of the multi-channel constant current drive module and the LED light source of an RGBY LED lamp with a traditional currentless control circuit;

[0020] Figure 3 is the internal module system block diagram of a multi-primary color LED lamp based on the present invention;

[0021] Figure 4 It is a schematic diagram of the current control circuit structure of the four - primary - color RGBY LED lamp based on the present invention;

[0022] Figure 5 It is a schematic connection diagram of the multi - channel constant - current drive module of the RGBY LED lamp based on the present invention and the corresponding current conversion and amplification sub - unit;

[0023] Figure 6 It is a comparison chart of the difference fluctuations between the actual LED current and the target current of blue light of 15 RGBY LED lamps with a traditional non - current - control circuit and those based on the present invention at the 2700K color temperature level;

[0024] Figure 7 It is a comparison chart of the difference fluctuations between the actual LED current and the target current of green light of 15 RGBY LED lamps with a traditional non - current - control circuit and those based on the present invention at the 2700K color temperature level;

[0025] Figure 8 It is a comparison chart of the difference fluctuations between the actual LED current and the target current of yellow light of 15 RGBY LED lamps with a traditional non - current - control circuit and those based on the present invention at the 2700K color temperature level;

[0026] Figure 9 It is a comparison chart of the difference fluctuations between the actual LED current and the target current of red light of 15 RGBY LED lamps with a traditional non - current - control circuit and those based on the present invention at the 2700K color temperature level;

[0027] Figure 10 It is a comparison chart of the correlated color temperature distributions of 15 RGBY LED lamps under two conditions: with a traditional non - current - control circuit and with the current - control circuit based on the present invention at the 2700K color temperature level;

[0028] Figure 11 It is a comparison chart of the correlated color temperature distributions of 15 RGBY LED lamps under two conditions: with a traditional non - current - control circuit and with the current - control circuit based on the present invention at the 3500K color temperature level;

[0029] Figure 12 It is a comparison chart of the correlated color temperature distributions of 15 RGBY LED lamps under two conditions: with a traditional non - current - control circuit and with the current - control circuit based on the present invention at the 4500K color temperature level.

[0030] Explanation of reference numerals:

[0031] 11. Driving control module, 21. Multi-channel constant current driving module, 31. Multi-primary color LED light source, 41. Multi-channel current detection module, 211. Blue LED driving unit, 212. Green LED driving unit, 213. Yellow LED driving unit, 214. Red LED driving unit, 311. Blue LED, 312. Green LED, 313. Yellow LED, 314. Red LED, 411. Multi-channel current conversion and amplification unit, 412. Current sampling control unit, 4111. Blue LED current conversion and amplification sub-unit, 4114. Red LED current conversion and amplification sub-unit, 4113. Yellow LED current conversion and amplification sub-unit, 4111. Blue LED current conversion and amplification sub-unit. Detailed implementation manners

[0032] The present invention will be further described below in conjunction with embodiments and with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention. It should be noted that the drawings of the present invention all adopt very simplified non-precise scales, only for the convenience and clarity of assisting in explaining the present invention.

[0033] Comparative example 1

[0034] As Figure 1 shown is the internal module system block diagram of a traditional multi-primary color LED lamp that does not adopt the current control circuit of the present invention, including a driving control module 11, a multi-channel constant current driving module 21, and a multi-primary color LED light source 31. The driving control module 11 directly controls the multi-channel constant current driving module 21 to output different driving currents to drive the multi-primary color LED light source 31. This process is open-loop, and the driving currents of each channel are easily affected by external factors and fluctuate.

[0035] Figure 2 is the connection schematic diagram of the multi-channel constant current driving module 21 and the LED light source 31 of a traditional RGBY LED lamp without a current control circuit. The multi-channel constant current driving module 21 is respectively composed of a blue LED driving unit 211, a green LED driving unit 212, a yellow LED driving unit 213, and a red LED driving unit 214. These four driving units are respectively the driving power supplies for the blue LED 311, green LED 312, yellow LED 313, and red LED 314 of the traditional RGBY LED lamp without a current control circuit.

[0036] Embodiment 1

[0037] As shown in the attached Figure 3As shown in the figure, the present invention provides a current control circuit for a multi-primary color LED lamp, which includes a drive control module 11, a multi-channel constant current drive module 21, a multi-primary color LED light source 31, and a multi-channel current detection module 41. The multi-primary color LED light source 31 is composed of a plurality of single-primary color LED light sources, and each single-primary color LED light source forms a single-primary color LED loop.

[0038] Among them, the multi-channel current detection module 41 is composed of a multi-channel current conversion and amplification unit 411 and a current sampling and control unit 412. The drive control module 11 is connected to and controls the multi-channel constant current drive module 21 to output adjustable multi-channel LED loop currents. The multi-channel current conversion and amplification unit 411 converts the current signals of each single-primary color LED loop into voltage signals and amplifies them. Each voltage signal is collected by the current sampling and control unit 412 and converted into current information, which is sent to the drive control module 11. The drive control module 11 internally stores the functional relationship between current and PWM wave duty cycle, the target current of each single-primary color LED channel under a specific light color, and the PID control algorithm program of each single-primary color LED, and controls the currents of each LED channel driven by the multi-channel constant current drive module 21 to track the set target current. Based on the internal modules of the multi-primary color LED lamp of the present invention, a closed-loop system is formed, which can feedback and control the current information of each channel in a closed loop.

[0039] As shown in the appendix Figure 4 As shown in the figure, in this embodiment, a RGBY four-primary color LED lamp is made with four independently driven and controlled blue LED, green LED, yellow LED, and red LED as the multi-primary color LED light source. Among them, the RGBY LED light source 31 includes a blue LED light source 311, a green LED light source 312, a yellow LED light source 313, and a red LED light source 314.

[0040] As shown in the appendix Figure 4 As shown in the figure, the multi-channel constant current drive module 21 includes a blue LED drive unit 211, a green LED drive unit 212, a yellow LED drive unit 213, and a red LED drive unit 214. The multi-channel current conversion and amplification unit 411 includes a blue LED current conversion and amplification sub-unit 4111, a green LED current conversion and amplification sub-unit 4112, a yellow LED current conversion and amplification sub-unit 4113, and a red LED current conversion and amplification sub-unit 4114. The control end B_PWM of the blue LED drive unit 211 is connected to the PWM0 port of the drive control module 11 as shown in Figure 4 ; the control end G_PWM of the green LED drive unit 212 is connected to the PWM1 port of the drive control module 11; the control end Y_PWM of the yellow LED drive unit 213 is connected to the PWM2 port of the drive control module 11; the control end R_PWM of the red LED drive unit 214 is connected to the PWM3 port of the drive control module 11.

[0041] Figure 5 In it, the blue LED driving unit 211 and the blue LED light source 311 are electrically connected to drive the blue LED light source 311. The sampling resistor R1 of the blue LED current conversion and amplification sub-unit 4111 is connected in series to the current loop formed by the blue LED driving unit 211 and the blue LED light source 311, and the potential difference across its two ends is linearly amplified by the blue LED current conversion and amplification sub-unit 4111. Since the driving circuits and conversion and amplification circuits of the four monochromatic LED light sources of blue, green, yellow, and red adopt the same scheme, therefore, taking one path of blue LED as an example, this paper introduces Figure 5 the specific structures and working principles of the LED driving unit and the corresponding LED current conversion and amplification sub-unit.

[0042] Figure 5 In it, the blue LED current conversion and amplification sub-unit 4111 is provided with a current sampling resistor R1, a first operational amplifier U1, a filter circuit, and a second operational amplifier U2. One end of the current sampling resistor R1 is connected to the negative electrode of the blue LED light source 311, and the other end is connected to one of the lead-out terminals of the blue LED driving unit 211; the positive electrode of the blue LED light source 311 is connected to the other lead-out terminal of the blue LED driving unit 211. The current sampling resistor R1, the blue LED driving unit 211, and the blue LED light source 311 form a current loop of the blue LED; the current sampling resistor is connected in parallel to the non-inverting input +IN and the inverting input -IN terminals of the first operational amplifier U1, and the first operational amplifier U1 linearly amplifies the potential difference across the two ends of the current sampling resistor R1. The capacitor C1 is connected in parallel with R1 to filter out high-frequency signals in the current loop of the blue LED. One end of the resistor R2 is connected to the output OUT terminal of the first operational amplifier U1, and the other end is connected to the connection point of the capacitor C2 and the resistor R3; one end of the capacitor C2 is connected to the connection point of the resistor R2 and R3, and the other end is grounded; one end of the resistor R3 is connected to the connection point of the resistor R2 and the capacitor C2, and the other end is connected to the non-inverting input +IN terminal of the second operational amplifier U2; one end of the capacitor C3 is connected to the non-inverting input +IN terminal of the second operational amplifier U2, and the other end is grounded. The resistor R2 and the capacitor C2 form a first-order low-pass filter, and the resistor R3 and the capacitor C3 form another first-order low-pass filter. These two first-order low-pass filters form a second-order low-pass filter for filtering out medium and high-frequency signals in the amplified signal output from the output OUT terminal of the first operational amplifier U1. One end of the resistor R4 is connected to the inverting -IN terminal of the second operational amplifier U2, and the other end is connected to the output OUT terminal of U2. At the same time, the output OUT terminal of the second operational amplifier U2 is connected to, for example, through the ADC_CH0 terminal, as Figure 3The ADC sampling input ADC0 channel of the current sampling control unit 412 shown. The second operational amplifier U2 is used as a voltage follower, and the voltage at the output OUT terminal is approximately equal to the voltage at the non-inverting +IN terminal. At the same time, the second operational amplifier U2 plays an isolation role to prevent voltage reading errors caused by reverse backflow current in the ADC channel of the current sampling control unit 412.

[0043] Similarly, Figure 5 The output OUT terminal of the second operational amplifier of the green LED current conversion and amplification sub-unit 4112 is connected to the ADC sampling input ADC1 channel of the current sampling control unit 412 through the ADC_CH1 terminal; the output OUT terminal of the second operational amplifier of the yellow LED current conversion and amplification sub-unit 4113 is connected to the ADC sampling input ADC2 channel of the current sampling control unit 412 through the ADC_CH2 terminal; the output OUT terminal of the second operational amplifier of the red LED current conversion and amplification sub-unit 4114 is connected to the ADC sampling input ADC3 channel of the current sampling control unit 412 through the ADC_CH3 terminal.

[0044] As Figure 4 Shown, the current sampling control unit 412 has at least 4 ADC channels, can convert analog voltage signals into digital values, and has an arithmetic function to convert the voltage values obtained by each ADC into current values. The serial port signal sending end TXD_1 of the current sampling control unit 412 is connected to the serial port signal receiving end U0RXD of the drive control module 11 through the TX terminal, and sends the converted current value to the drive control module 11 in a serial communication manner.

[0045] Based on the current control circuit of the four-primary-color RGBY LED lamp in this Embodiment 4, a control method that can effectively reduce the color difference between the four-primary-color RGBY LED lamps is as follows:

[0046] S1: Test and record the current of each primary-color LED of the RGBY LED lamp and the duty cycle data of the corresponding PWM wave output by the drive control module 11, and perform polynomial fitting on the current and duty cycle through mathematical calculation software.

[0047] The functional relationship between the duty cycle DutyB of the PWM wave corresponding to the blue LED light source 311 and the current IB is:

[0048] DutyB = a1 + b1 * IB (1)

[0049] The functional relationship between the duty cycle DutyG of the PWM wave corresponding to the green LED light source 312 and the current IG is:

[0050] DutyG = a2 + b2 * IG (2)

[0051] The functional relationship between the PWM wave duty cycle DutyY and the current IY corresponding to the yellow LED light source 313 is:

[0052] DutyY = a3 + b3 * IY (3)

[0053] The functional relationship between the PWM wave duty cycle DutyR and the current IR corresponding to the red LED light source 314 is:

[0054] DutyR = a4 + b4 * IR (4)

[0055] In the above formulas (1), (2), (3), and (4), a1, b1, a2, b2, a3, b3, a4, and b4 are the polynomial fitting coefficients of the loop current and the duty cycle.

[0056] S2: Store the target currents IB_Goal, IG_Goal, IY_Goal, and IR_Goal of the blue, green, yellow, and red LED loops under a specific light color (2700K, 3500K, or 4500K), the functional relationships (1), (2), (3), and (4) between the LED loop current and the duty cycle obtained in step S1, and the PID control algorithm program of the corresponding color LED in the drive control module 11.

[0057] S3: According to the relationships (1), (2), (3), and (4), obtain the initial duty cycles DutyB_Init, DutyG_Init, DutyY_Init, and DutyR_Init of the PWM waves corresponding to the target currents IB_Goal, IG_Goal, IY_Goal, and IR_Goal of the blue, green, yellow, and red LED loops when the RGBY LED lamp is powered on, and output the PWM waves with duty cycles DutyB_Init, DutyG_Init, DutyY_Init, and DutyR_Init to the control terminals of the corresponding blue, green, yellow, and red LED loops in the multi-channel constant current drive module 21.

[0058] S4: Four of the ADC channels of the current sampling control unit 412 of the multi-channel current detection module 41 respectively and in real time collect the currents IB_Actual, IG_Actual, IY_Actual, and IR_Actual of the blue, green, yellow, and red LED circuits, encode each current value, and send it to the drive control module 11 through serial communication. The drive control module 11 receives the data and decodes it to obtain the actual current data of the blue, green, yellow, and red LED circuits of the RGBY LED lamp. And calculate the differences IB_Error, IG_Error, IY_Error, IR_Error between the target currents IB_Goal, IG_Goal, IY_Goal, IR_Goal and the actual currents IB_Actual, IG_Actual, IY_Actual, IR_Actual of the blue, green, yellow, and red LEDs, that is:

[0059] IB_Error = IB_Goal - IB_Actual (5)

[0060] IG_Error = IG_Goal - IG_Actual (6)

[0061] IY_Error = IY_Goal - IY_Actual (7)

[0062] IR_Error = IR_Goal - IR_Actual (8)

[0063] The drive control module 11 uses the PID control algorithm for the current errors IB_Error, IG_Error, IY_Error, IR_Error to obtain the adjusted currents IB_New, IG_New, IY_New, IR_New of the LED circuits in the multi-primary color LED lamp, and obtains the new PWM wave duty cycles DutyB_New, DutyG_New, DutyY_New, DutyR_New corresponding to the blue, green, yellow, and red LEDs through formulas (1), (2), (3), (4), and inputs each PWM wave with the adjusted duty cycle to the control ends corresponding to the blue, green, yellow, and red LED circuits of the multi-channel constant current drive module 21.

[0064] S5: Loop through step S4, and preset a dynamic adjustment time of no less than 10 minutes for step S4. After this time, the light sources of each primary color LED of the RGBY LED lamp tend to be thermally stable, and after the adjustment ends, the currents of each primary color LED circuit also tend to be stable, and are basically close to the target currents IB_Goal, IG_Goal, IY_Goal, IR_Goal set in step S2.

[0065] S6: Based on the current control circuit of RGBY LED lights, the control method of steps S2 to S5 above is adopted for different RGBY LED lamps of the same model. The current of each single - primary - color LED circuit is tracked in real time to achieve the color - light uniformity of different RGBY LED lights of the same model under the same lighting mode.

[0066] In order to more intuitively compare the effects produced by the current control circuit of the present invention with those of the traditional technology, now, the difference fluctuations between the actual LED currents and the target currents of different primary - color lights (blue light, green light, yellow light, red light) of 15 RGBY LED lights without a current control circuit in the traditional technology and 15 RGBY LED lights of the present invention under the 2700K color - temperature range are compared. The results are shown in Figure 6 、 7 、8, 9. It can be seen that the monochromatic - light current fluctuation degree among different RGBY LED lamps of the present invention is smaller than that of the RGBY LED lights of the traditional non - current - control circuit.

[0067] The correlated - color - temperature distributions of 15 RGBY LED lights under two situations, namely, the traditional non - current - control circuit and the current control circuit based on the present invention, at different color - temperature ranges (2700K, 3500K, 4500K) are compared. It can be known that through the current control circuit and control method of the present invention, the color - light differences among different RGBY LED lights of the same batch under the same lighting mode are effectively reduced. The specific effects are as shown in Figure 10 、 Figure 11 、 Figure 12 shown.

[0068] Table 1 shows the maximum color - temperature differences among 15 lights with and without current control at different color - temperature ranges of 2700K, 3500K, and 4500K. The color - temperature difference among the lights with the current control circuit based on the present invention is significantly smaller than the maximum color - temperature difference among the lights without current control.

[0069] Table 1

[0070]

[0071] In summary, it can be seen that the current control circuit and control method provided by the present invention can control the currents of the same - primary - color LED circuits among different lamps of the same model to be basically the same, thereby greatly improving the color - light differences among different multi - primary - color LED lights.

[0072] The embodiments described above are only one of the embodiments of the present invention, and obviously not all of them, and are not used to limit the present invention. Any modifications, equivalent transformations, improvements, etc. made within the principle and spirit of the present invention, as well as various substitutions and changes made by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts, shall all be included within the protection scope of the present invention.

Claims

1. A current control circuit for a multi-primary-color LED lamp, characterized in that: It includes a multi-channel current detection module, a multi-channel constant current drive module, a drive control module, and a multi-primary color LED light source. The multi-primary color LED light source is composed of multiple single-primary color LED light sources. The multi-channel current detection module is composed of a multi-channel current conversion and amplification unit and a current sampling and control unit. The drive control module is connected to and controls the multi-channel constant current drive module to output adjustable multi-channel LED loop currents. The multi-channel current conversion and amplification unit converts the current signals of each single-primary color LED loop into voltage signals and amplifies them respectively. Each voltage signal is collected by the corresponding current sampling and control unit and converted into current information, which is sent to the drive control module. The drive control module internally stores the functional relationship between the current of each single-primary color LED loop and the duty cycle of the corresponding PWM wave, the target current of each single-primary color LED loop under a specific light color, and the PID control algorithm program, and controls the current of each single-primary color LED loop output by the multi-channel constant current drive module to track the set target current; The multi-channel current conversion and amplification unit includes multiple current conversion and amplification sub-units. Each current conversion and amplification sub-unit includes a current sampling resistor, a first operational amplifier circuit, a filter circuit, and a second operational amplifier circuit. The two ends of the current sampling resistor are connected in parallel to the in-phase and anti-phase ends of the first operational amplifier circuit, and are connected in series with the single-primary color LED light source in the corresponding LED loop. The output end of the first operational amplifier circuit is connected to the input end of the filter circuit, and the output end of the filter circuit is connected to the input end of the second operational amplifier circuit; The first operational amplifier circuit plays a role in current conversion and amplification. It adopts a differential amplification structure to linearly amplify the potential difference across the current sampling resistor. The second operational amplifier circuit follows the input voltage and plays an isolation role.

2. The current control circuit of the multi-primary-color LED lamp according to claim 1, wherein: The drive control module includes a storage unit, an operation control unit, and multiple PWM wave output channels. The storage unit stores the functional relationship between the current of each single-primary color LED loop and the duty cycle of the corresponding PWM wave, the target current value of each single-primary color LED loop under a specific light color, and the PID control algorithm program. The operation control unit is used to decode the signal sent by the current sampling and control unit to obtain the actual current value of each single-primary color LED loop, and based on the error between the actual current and the target current of each single-primary color LED loop, use the PID algorithm to control the duty cycle of the PWM wave of each single-primary color LED loop. The PWM wave output channels corresponding to each single-primary color LED loop are respectively connected to the signal control ends of the corresponding single-primary color LED loops of the multi-channel constant current drive module.

3. The current control circuit of the multi-primary-color LED lamp according to claim 1, wherein: The current sampling and control unit is internally provided with a multi-channel analog-to-digital converter. The output ends of the second operational amplifier circuits corresponding to each single-primary color LED loop are respectively connected to the input ends of the corresponding analog-to-digital converter channels. The signal sending end of the current sampling and control unit is connected to the signal receiving end of the drive control module.

4. The current control circuit of the multi-primary color LED lamp according to claim 1, wherein: The filter circuit adopts an RC second-order filter circuit.

5. A control method for a current control circuit of a multi-primary-color LED lamp according to claim 1, characterized in that: Specifically, it includes the following steps: S1: Test and record the duty cycle Dutyi of the PWM wave output from the multi-channel drive control module to each primary color LED loop driven by the multi-channel constant current drive module and the drive current Ii data of the corresponding primary color LED loop. Use mathematical calculation software to perform polynomial fitting on Ii and Dutyi to obtain the functional relationship Dutyi = ai + bi * Ii, where i represents the i-th primary color, and ai and bi are the fitting coefficients of the current and duty cycle corresponding to the i-th primary color LED loop respectively; S2: Store the functional relationship obtained in step S1, the target current Ii_Goal of each primary color LED loop under a specific light color, and the PID control algorithm program in the drive control module; S3: According to the functional relationship obtained in step S1, obtain the duty cycle Dutyi_Init of the PWM wave corresponding to the target current Ii_Goal of each primary color LED loop. When the multi-primary color LED is turned on, output the PWM wave with a duty cycle of Dutyi_Init to the corresponding control terminals of each primary color LED loop in the multi-channel constant current drive module; S4: The current sampling control unit real-time collects the actual current Ii_Actual of each primary color LED, and sends the actual current data Ii_Actual of each primary color LED loop to the drive control module according to a specific coding method. The drive control module decodes it, calculates the difference Ii_ERROR between the target current Ii_Goal and the actual current Ii_Actual of each primary color LED. The drive control module uses the PID control algorithm for Ii_ERROR to obtain the adjusted current Ii_New of each primary color LED loop in the multi-primary color LED, and obtains the duty cycle Dutyi_New of the PWM wave corresponding to each primary color LED loop that needs to be adjusted in real time through the functional relationship obtained in step S! Output the PWM wave corresponding to each primary color LED loop with the adjusted duty cycle to the corresponding control terminals of each primary color LED loop in the multi-channel constant current drive module; S5: Loop step S4, and preset the dynamic adjustment time of step S4 to be no less than 10 minutes. After the dynamic adjustment time, the light sources of each primary color LED in the multi-primary color LED tend to be thermally stable. After the adjustment is completed, the current of each primary color LED loop also tends to be stable, and is basically close to the target current value Ii_Goal in step S2; S6: Based on the current control circuit of the multi-primary color LED, adopt the control method from step S2 to step S5 for different multi-primary color LEDs of the same model to real-time track the current of each single primary color LED loop.

6. The control method of the current control circuit of the multi-primary-color LED lamp according to claim 5, characterized in that: In step S4, the specific coding method is one of multiple coding protocols such as serial communication, SPI bus, Bluetooth, WIFI, IIC bus, RS485, and DMX512.

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