Constant current driving circuit, circuit input power calculation method and lamp

Abstract

The invention provides a constant-current driving circuit, a circuit input power calculation method and a lamp, and the circuit comprises a constant-voltage module which converts an external alternating current into a constant-voltage direct current, and the negative output end of the constant-voltage module is connected with a first resistor; the constant current module is connected with the constant voltage module and converts the direct current with constant voltage into direct current with constant current; the operational amplifier detection module detects the voltage of the first resistor; the control module is connected with the output positive end of the constant-voltage module, detects the output voltage of the constant-voltage module and is further connected with the operational amplifier detection module, and the output end of the control module is connected with the constant-current module and is configured to output signals to the constant-current module; the operational amplifier detection module amplifies the detected voltage of the first resistor through a preset amplification factor and then outputs the amplified voltage to the control module, and the control module can calculate the input power of the constant-current driving circuit according to the detected output voltage of the constant-voltage module and the voltage of the first resistor.

Description

Technical Field

[0001] The present invention relates to the field of lighting, and in particular to a constant current drive circuit, a circuit input power calculation method and a lamp. Background Art

[0002] With the improvement of living standards, LED lighting is increasingly used in many scenarios, among which smart lighting is also increasingly widely used in people's real lives. People control LED lamps to meet more usage needs.

[0003] Smart lighting can easily adjust the color temperature and current of LED lamps through various control methods such as Bluetooth, WIFI, PLC, DALI, 0-10V, etc., to meet people's diverse usage scenarios and needs. In smart lighting, communication modules (Bluetooth, WIFI, PLC, DALI, 0-10V, etc.) are generally used to communicate with the outside, and the external control information is transmitted to the MCU. The MCU then converts the transmitted control information into a PWM signal to control the working state of the driver. Under different PWM signals, the output current is different, and the LED voltage is also different. In this way, it will be more complicated to detect the input power, which often requires more cost.

[0004] In view of this, it is indeed necessary to provide a constant current driving circuit, a circuit input power calculation method and a lamp to solve the above problems. Summary of the invention

[0005] The object of the present invention is to provide a constant current driving circuit, a circuit input power calculation method and a lamp.

[0006] To achieve the above object, the present invention provides a constant current drive circuit, comprising:

[0007] A constant voltage module, used for converting external alternating current into direct current with a constant voltage, wherein a first resistor is connected to the negative output terminal of the constant voltage module;

[0008] A constant current module, connected to the constant voltage module, the constant current module being configured to convert a direct current of a constant voltage into a direct current of a constant current;

[0009] An operational amplifier detection module, wherein an input terminal of the operational amplifier detection module is connected to two ends of the first resistor and is configured to detect a voltage of the first resistor;

[0010] A control module, wherein the control module is connected to the positive output terminal of the constant voltage module to detect the output voltage of the constant voltage module, the control module is also connected to the operational amplifier detection module, and the output terminal of the control module is connected to the constant current module and is configured to output a signal to the constant current module;

[0011] The operational amplifier detection module amplifies the detected voltage of the first resistor and outputs it to the control module. The control module calculates the input power of the constant current drive circuit according to the detected output voltage of the constant voltage module and the voltage of the first resistor.

[0012] As a further improvement of the present invention, the constant current module includes two voltage-dividing resistors, which are connected in series to the output end of the constant voltage module. After voltage division by the two voltage-dividing resistors, an analog voltage is obtained and transmitted to the control module. After conversion, the control module obtains the output voltage of the constant voltage module.

[0013] As a further improvement of the present invention, the constant current module includes a warm light constant current module and a cold light constant current module connected in parallel to each other, which are used to supply power to the corresponding warm light LED load and cold light LED load respectively.

[0014] As a further improvement of the present invention, the control module outputs two PWM signals. The control module outputs a warm light PWM signal to the warm light constant current module, and the control module outputs a cold light PWM signal to the cold light constant current module.

[0015] As a further improvement of the present invention, the operational amplifier detection module includes an operational amplifier chip, an eleventh resistor, and an eighth resistor, wherein one end of the eleventh resistor is connected to the first resistor, and the other end is connected to the input end of the operational amplifier chip, and the output end of the operational amplifier chip outputs current to the control module through the eighth resistor.

[0016] As a further improvement of the present invention, the control module is an MCU controller, the constant voltage module adopts a flyback isolation architecture, and the constant current module adopts a Buck constant current architecture.

[0017] Another object of the present invention is to provide a method for calculating circuit input power.

[0018] To achieve the above object, the present invention provides a circuit input power calculation method for calculating the power of the above constant current drive circuit, comprising the following steps:

[0019] Step S1: the operational amplifier detection module detects the voltage of the first resistor and amplifies it and outputs it to the control module;

[0020] Step S2: the control module converts the received voltage of the first resistor to obtain the output current of the constant current drive circuit, and the control module detects the output voltage of the constant voltage module;

[0021] Step S3: the control module calculates the output power of the constant voltage module according to the output current of the constant current drive circuit and the output voltage of the constant voltage module;

[0022] Step S4: the control module calculates the input power of the constant current drive circuit according to the output power of the constant voltage module.

[0023] As a further improvement of the present invention, the formula for calculating the input power of the constant voltage module in step S4 is as follows:

[0024] Pi = Po / η;

[0025] Where Pi represents the input power of the constant voltage module, Po represents the input efficiency of the constant voltage module, and η represents the efficiency of the constant voltage module.

[0026] Another object of the present invention is to provide a lamp including the above constant current driving circuit.

[0027] To achieve the above object, the present invention provides a lamp, comprising the above constant current driving circuit.

[0028] As a further improvement of the present invention, the lamp includes two light source modules with different color temperatures, and the light source modules are connected to the constant current drive circuit through a total of four wires, LEDW+, LEDW-, LEDC+, and LEDC-, wherein LEDW+ and LEDC+ are common anodes in the constant current drive circuit and are directly connected to the output end of the constant voltage module.

[0029] The beneficial effect of the present invention is that compared with the prior art, the constant current driving circuit of the present invention utilizes the set operational amplifier detection module to detect the output current of the constant voltage module and transmits it to the control module. At the same time, the control module detects the output current of the constant voltage module, and then calculates the input power of the constant current driving circuit according to the efficiency value of the constant voltage module. The error between the calculated input power and the actual input power is smaller, the overall circuit is simpler, and it has better economy and practicality. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 It is a principle block diagram of a constant current driving circuit according to a preferred embodiment of the present invention.

[0031] Figure 2 4 is a circuit diagram of a constant current driving circuit according to a preferred embodiment of the present invention.

[0032] 100-constant current driving circuit;

[0033] 10-constant voltage module, 20-constant current module, 30-control module, 40-op amp detection module, 50-LED module; DETAILED DESCRIPTION

[0034] In order to make the purpose, technical solutions and advantages of the present invention more clear, the present invention is described in detail below with reference to the accompanying drawings and specific embodiments.

[0035] It should be noted here that in order to avoid obscuring the present invention due to unnecessary details, only structures and / or processing steps closely related to the scheme of the present invention are shown in the accompanying drawings, while other details that are not closely related to the present invention are omitted.

[0036] In addition, it should be noted that the terms "comprises", "includes" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, article or apparatus that includes a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or apparatus.

[0037] See also Figures 1-2 As shown, the constant current driving circuit 100 of the present invention comprises:

[0038] The constant voltage module 10 is used to convert external alternating current into direct current with a constant voltage. The negative output terminal of the constant voltage module 10 is connected to a first resistor R1.

[0039] A constant current module 20 is connected to the constant voltage module 10, and the constant current module 20 is configured to convert the DC power of the constant voltage into the DC power of the constant current;

[0040] An operational amplifier detection module 40, wherein the input end of the operational amplifier detection module 40 is connected to both ends of the first resistor R1, and is configured to detect the voltage of the first resistor R1;

[0041] The control module 30 is connected to the positive output terminal of the constant voltage module 10 to detect the output voltage of the constant voltage module 10. The control module 30 is also connected to the operational amplifier detection module 40. The output terminal of the control module 30 is connected to the constant current module 20 and is configured to output a signal to the constant current module 20.

[0042] The operational amplifier detection module 40 amplifies the detected voltage of the first resistor R1 by a preset amplification factor and outputs it to the control module 30. The control module 30 calculates the input power Pi of the constant current drive circuit 100 based on the detected output voltage Vo of the constant voltage module 10 and the voltage Vr of the first resistor R1.

[0043] The constant current driving circuit 100 of the present invention can accurately detect the voltage Vr on the first resistor R1 connected to the output end of the constant voltage module 10 through the operational amplifier detection module 40 and transmit it to the control module 30. At the same time, the control module 30 detects the output voltage Vo of the constant voltage module 10. Based on the above two values, the control module 30 can calculate the input power Pi of the constant current driving circuit 100.

[0044] In some embodiments, the constant current module 20 includes two voltage-dividing resistors, which are connected in series to the output end of the constant voltage module 10. After voltage division by the two voltage-dividing resistors, an analog voltage is obtained and transmitted to the control module 30. After conversion, the control module 30 obtains the output voltage Vo of the constant voltage module 10. The control module 30 includes an ADC for converting analog signals.

[0045] The constant current module 20 includes a warm light constant current module and a cold light constant current module connected in parallel, which are used to supply power to the corresponding warm light LED load and cold light LED load respectively.

[0046] Preferably, the control module 30 outputs two PWM signals. The control module 30 outputs a warm light PWM signal to the warm light constant current module, and the control module 30 outputs a cold light PWM signal to the cold light constant current module. In other embodiments, corresponding to different color temperatures, it can also be a single-channel or multi-channel output, and the present invention is not limited to this.

[0047] The operational amplifier detection module 40 includes an operational amplifier chip, an eleventh resistor R11, and an eighth resistor R8, wherein one end of the eleventh resistor R11 is connected to the first resistor R1, and the other end is connected to the input end of the operational amplifier chip U1, and the output end of the operational amplifier chip U1 outputs the current to the control module 30 through the eighth resistor R8. The operational amplifier chip U1 and the resistors around it form a unidirectional operational amplifier, which can amplify the input signal in the same direction by 1+R8 / R11 times, the eleventh resistor R11 is connected to the first resistor R1, and the first resistor R1 is connected to the GND end of the constant voltage module 10. Current flows through the first resistor R1, thus generating a voltage difference, which is amplified by the unidirectional operational amplifier and provided to the control module 30. The control module 30 performs ADC sampling on the analog signal to obtain a voltage, and then divides it by the amplification factor of the unidirectional operational amplifier and the resistance value of the first resistor R1, and obtains the output current Io of the constant voltage module 10, and the output power of the constant voltage module 10 is Po=Io*Vo.

[0048] The control module 30 is an MCU controller, the constant voltage module 10 adopts a flyback isolation architecture, and the constant current module 20 adopts a Buck constant current architecture. In other embodiments, the constant voltage module 10 can be other power architectures or non-isolated architectures, as long as it can generate a fixed voltage; the constant current module 20 can also be other power architectures such as Boost, Buck-Boost, etc., as long as it is a constant current architecture with PWM dimming function; the control module 30 can also use other types of controllers, and the present invention is not limited to this.

[0049] The present invention also provides a circuit input power calculation method for calculating the power of the above-mentioned constant current drive circuit 100, comprising the following steps:

[0050] Step S1: The operational amplifier detection module 40 detects the voltage Vr of the first resistor R1 and amplifies it by n times and then outputs it to the control module 30;

[0051] Step S2: The control module 30 converts the received voltage of the first resistor R1 to obtain the output current Io of the constant current drive circuit 100. The current received by the control module 30 can be obtained by the formula I=Vr*n / R1, and then divided by the amplification factor n to obtain the output current Io of the constant current drive circuit 100. At the same time, the control module 30 detects the output voltage Vo of the constant voltage module 10;

[0052] Step S3: the control module 30 calculates the output power Po of the constant voltage module 10 according to the output current Io of the constant current driving circuit 100 and the output voltage Vo of the constant voltage module 10, and the calculation formula is Po=Io*Vo;

[0053] Step S4 : the control module 30 calculates the input power of the constant voltage module 10 according to the output power of the constant voltage module 10 , and the calculation formula is Pi=Po / η, where η represents the efficiency of the constant voltage module 10 .

[0054] The MCU controller stores a data table, and the MCU controller determines the efficiency value η of the constant voltage module 10 corresponding to the actual duty cycle by looking up the table according to the actual duty cycle.

[0055] Since the efficiency of the constant current drive circuit 100 is determined after the device selection, the efficiency difference of each constant current drive circuit 100 will not be too much. Take x test points (usually 10 points, i.e. one point for every 10% duty cycle) from 1% to 100% of the duty cycle D, and take the efficiency of multiple test constant current drive circuits 100 at the corresponding duty cycle at each point, and then take the average. In this way, the efficiency values ​​η of the x duty cycle points are obtained, and these values ​​are burned into the MCU. According to the current PWM duty cycle D, the MCU divides the output power Po of the constant voltage module 10 after sampling and calculation by the corresponding efficiency value η to obtain the current input power Pi.

[0056] The present invention further provides a lamp, comprising the above-mentioned constant current driving circuit 100.

[0057] The lamp includes two light source modules 50 with different color temperatures. The light source module 50 is connected to a constant current drive circuit 100 through four wires, LEDW+, LEDW-, LEDC+, and LEDC-. LEDW+ and LEDC+ are common anodes on the constant current drive circuit 100 and are directly connected to the output end of the constant voltage module 10.

[0058] The following is an application of the constant current drive circuit 100 of the present invention in an intelligent constant current drive with 2-way PWM dimming of constant current output. The constant current drive circuit 100 includes a constant voltage module 10, an MCU, and a constant current module 20. The constant current module 20 is an independent 2-way buck circuit, and the output current can be adjusted by the PWM signal of the MCU.

[0059] The MCU can output two PWM signals, PWMW and PWMC, which are respectively connected to the dimming PWM pins of the two dimming BUCKs. The MCU has other functions in this intelligent drive, which will not be described in this embodiment.

[0060] The LED lamp light source is composed of two light source modules 50 with different color temperatures, which are respectively connected to the two outputs of the driver. One light source module 50 is an LED string with a color temperature of 2700K, and the other light source module 50 is an LED string with a color temperature of 6500K. Different color temperatures and brightness can be obtained by different currents. The LED light source module 50 is connected to the driver through a total of 4 wires, LEDW+, LEDW-, LEDC+, and LEDC-. The LEDW+ and LEDC+ of these 4 wires are common anodes on the constant current drive circuit 100, that is, they are in a short-circuited state on the constant current drive circuit 100 and are directly connected to the output end of the constant voltage module 10.

[0061] The constant voltage module 10 is used to convert the grid voltage into a fixed voltage. This module is not limited to the architecture. In this example, it is a flyback isolation architecture. It can also be other power architectures or non-isolated architectures, as long as it can generate a fixed voltage. In this embodiment, the output is marked as 50V. In other embodiments, this voltage can be any suitable voltage according to the actual situation, and the present invention does not limit this.

[0062] The constant current module 20 in this example is a Buck constant current architecture, and can also be other architecture power architectures such as Boost, Buck-Boost, etc., as long as it has a PWM dimming function. This example has two constant currents, corresponding to different color temperatures, and can also be single or multi-channel.

[0063] The voltage-dividing resistors include a second resistor R2 and a fourth resistor R4, which are connected to the output terminal 50V of the constant voltage module 10. After the second resistor R2 and the fourth resistor R4 divide the voltage, an analog voltage is obtained and transmitted to the PIN10 of the MCU. The MCU performs ADC sampling on the analog signal and multiplies it by the voltage-dividing ratio of the second resistor R2 and the fourth resistor R4 to obtain the output voltage Vo of the constant voltage module 10.

[0064] The operational amplifier chip U1 and the surrounding resistors form a unidirectional operational amplifier, which can amplify the input signal in the same direction by 1+R8 / R11 times. In this embodiment, the eighth resistor R8 is 220K, and the eleventh resistor R11 is 22K, so the operational amplifier amplifies the signal in the same direction by 11 times. The input end of the unidirectional amplifier is connected to the first resistor R1, and the first resistor R1 is connected to the GND end of the constant voltage module 10. Current flows through the first resistor R1, which generates a voltage difference. The unidirectional operational amplifier amplifies the voltage difference by 11 times and provides it to the MCU Pin9 foot. The MCU performs ADC sampling on this analog signal to obtain the voltage and then converts it to obtain the output current Io of the constant current drive circuit 100, and the output power of the constant voltage module 10 is Po=Io*Vo.

[0065] Usually, the components of the constant current drive circuit 100 are mass-produced according to the specifications, and the overall error is not large, and the overall efficiency is not much different. The overall input power can be calculated by pre-testing the efficiency of other constant current drive circuits 100. The driving efficiency is different under different duty cycles. Therefore, it is necessary to test the efficiency under different duty cycles in advance and then store the data in the MCU. In actual calculation, the MCU finds the corresponding efficiency value through the PWM duty cycle output by itself and then derives the efficiency. You can first select m constant current drive circuits 100, and then divide the duty cycle from 0-100% into x parts. The larger the number of x, the more data needs to be tested, and the more accurate the final result. Under different PWM duty cycles of x, measure the efficiency values ​​of m constant current drive circuits 100 and take the average value, and make the duty cycle corresponding to these x average efficiency values ​​into a data table and store it in the MCU. The MCU reads the efficiency value η according to the corresponding actual duty cycle, and the actual drive input power is Pi=Po / η.

[0066] The circuit input power calculation method proposed in the present invention is not equivalent to the actual power detection, and there is a difference with the value detected by the power meter. The actual comparison shows that the error can be controlled within 5%. However, in the power detection application with low requirements, it has the characteristics of simple circuit. It only needs to detect Vo and Io of the constant voltage module 10 and then obtain the efficiency value through the MCU table lookup and then calculate. In this way, the peripheral circuit is relatively simple.

[0067] In summary, the constant current driving circuit 100 of the present invention utilizes the operational amplifier detection module 40 to detect the output current of the constant voltage module 10 and transmits it to the control module 30. At the same time, the control module 30 detects the output current of the constant voltage module 10, and then calculates the input power of the constant current driving circuit 100 according to the efficiency value of the constant voltage module 10. The error between the calculated input power and the actual input power is smaller, the overall circuit is simpler, and it has better economy and practicality.

[0068] The above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, it should be understood by those skilled in the art that the technical solution of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical solution of the present invention.

Claims

1. A constant current driving circuit, characterized in that: include: A constant voltage module (10) is used to convert external alternating current into direct current with a constant voltage, and a first resistor (R1) is connected to the negative output terminal of the constant voltage module (10); A constant current module (20) connected to the constant voltage module (10), the constant current module (20) being configured to convert direct current with a constant voltage into direct current with a constant current; An operational amplifier detection module (40), wherein an input end of the operational amplifier detection module (40) is connected to two ends of the first resistor (R1) and is configured to detect a voltage of the first resistor (R1); A control module (30), the control module (30) being connected to the positive output terminal of the constant voltage module (10) to detect the output voltage of the constant voltage module (10), the control module (30) being further connected to the operational amplifier detection module (40), the output terminal of the control module (30) being connected to the constant current module (20) and being configured to output a signal to the constant current module (20); The operational amplifier detection module (40) amplifies the detected voltage of the first resistor (R1) and outputs the amplified voltage to the control module (30); the control module (30) calculates the input power of the constant current drive circuit based on the detected output voltage of the constant voltage module (10) and the voltage of the first resistor (R1).

2. The constant current driving circuit according to claim 1, characterized in that: The constant current module (20) comprises two voltage-dividing resistors, the two voltage-dividing resistors are connected in series to the output end of the constant voltage module (10), and an analog voltage is obtained after voltage division by the two voltage-dividing resistors and transmitted to the control module (30). The control module (30) obtains the output voltage of the constant voltage module (10) after conversion.

3. The constant current driving circuit according to claim 1, characterized in that: The constant current module (20) comprises a warm light constant current module (20) and a cold light constant current module (20) connected in parallel to each other, and is used to supply power to a corresponding warm light LED load and a cold light LED load respectively.

4. The constant current driving circuit according to claim 3, characterized in that: The control module (30) outputs two PWM signals. The control module (30) outputs a warm light PWM signal to the warm light constant current module (20), and the control module (30) outputs a cold light PWM signal to the cold light constant current module.

5. The constant current driving circuit according to claim 1, characterized in that: The operational amplifier detection module (40) comprises an operational amplifier chip (U1), an eleventh resistor (R11), and an eighth resistor (R8), wherein one end of the eleventh resistor (R11) is connected to the first resistor (R1), and the other end is connected to the input end of the operational amplifier chip (U1), and the output end of the operational amplifier chip (U1) outputs current to the control module (30) through the eighth resistor (R8).

6. The constant current driving circuit according to claim 1, characterized in that: The control module (30) is an MCU controller, the constant voltage module (10) adopts a flyback isolation architecture, and the constant current module (20) adopts a Buck constant current architecture.

7. A method for calculating circuit input power, characterized in that: The method for calculating the input power of the constant current driving circuit according to any one of claims 1 to 6 comprises the following steps: Step S1: the operational amplifier detection module (40) detects the voltage of the first resistor (R1), amplifies the voltage and outputs it to the control module (30); Step S2: the control module (30) converts the received voltage of the first resistor (R1) to obtain the output current of the constant current drive circuit, and at the same time the control module (30) detects the output voltage of the constant voltage module (10); Step S3: the control module (30) calculates the output power of the constant voltage module (10) according to the output current of the constant current drive circuit and the output voltage of the constant voltage module (10); Step S4: the control module (30) calculates the input power of the constant current drive circuit according to the output power of the constant voltage module (10).

8. The circuit input power calculation method according to claim 7, characterized in that: The formula for calculating the input power of the constant voltage module (10) in step S4 is as follows: Pi = Po / η; Wherein Pi represents the input power of the constant voltage module (10), Po represents the input efficiency of the constant voltage module (10), and η represents the efficiency of the constant voltage module (10).

9. A lamp, characterized in that: The lamp comprises the constant current driving circuit as claimed in any one of claims 1 to 6.

10. The lamp according to claim 9, characterized in that: The lamp comprises two light source modules (50) with different color temperatures, the light source module (50) being connected to the constant current drive circuit via a total of four wires, namely LEDW+, LEDW-, LEDC+, and LEDC-, wherein LEDW+ and LEDC+ are common anodes in the constant current drive circuit and are directly connected to the output end of the constant voltage module (10).

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