Constant current circuit based on direct current-direct current converter and control method

Abstract

The invention provides a DC-DC converter-based constant current circuit and a control method, and the circuit comprises a voltage collection port and a control system device for controlling an output port, and the voltage collection port is connected with a loop connected with a load and is configured to collect a first voltage value generated by a current flowing through the load at a first resistor; the control output port is configured to generate and output a first signal based on the first voltage value; the post-processing module is configured to post-process the first signal and output a second signal; comprising a power supply input port, a power supply output port and a signal feedback input port, the power supply input port is connected with an external power supply, the power supply output port is connected with a load, and the signal feedback input port is connected with the power supply output port through a voltage division loop. The signal feedback input port is connected with the post-processing module and is configured to receive a second signal output by the post-processing module, and the DC-DC converter is configured to adjust the output voltage of the power output port based on the second signal, so that the current flowing through the load is constant.

Description

Technical Field

[0001] The present invention relates to the technical field of constant current circuits, and in particular to a constant current circuit and a control method based on a DC-DC converter. Background Art

[0002] A constant current device is an electronic component or circuit whose main function is to keep the output current stable at a set value when the load conditions or power supply voltage change. Constant current devices are widely used in various electronic devices, especially in applications that require constant current, such as LED drivers, chargers, power supplies, and sensor circuits. For example, as a constant current device, the brightness of LED depends mainly on current rather than voltage. Currently, LEDs can be driven by constant current chips to achieve constant current. However, constant current chips are expensive and less flexible to use.

[0003] Therefore, it is desirable to provide a constant current circuit and control method based on a DC-DC converter, which can effectively reduce costs and have high flexibility in use. Summary of the invention

[0004] One or more embodiments of the present specification provide a constant current circuit based on a DC-DC converter, the circuit comprising: a control system device, the control system device comprising a voltage acquisition port and a control output port; the voltage acquisition port is connected to a loop connected to a load, and is configured to acquire a first voltage value generated on a first resistor by a current flowing through the load; the control output port is configured to generate and output a first signal based on the first voltage value, wherein the load is connected in series with the first resistor, and the load is a constant current device; a post-processing module is configured to post-process the first signal and output a second signal; a DC-DC converter, the DC-DC converter comprising a power input port, a power output port and a signal feedback input port; the power input port is connected to an external power supply, the power output port is connected to the load, the signal feedback input port is connected to the power output port through a voltage divider loop, and the signal feedback input port is also connected to the post-processing module, and is configured to receive the second signal output by the post-processing module; the DC-DC converter is configured to adjust the output voltage of the power output port based on the second signal to make the current flowing through the load constant.

[0005] One or more embodiments of the present specification provide a control method for a constant current circuit based on a DC-DC converter, the method comprising: collecting a first voltage value generated on a first resistor by a current flowing through a load based on a control system device; generating and outputting a first signal based on the first voltage value, wherein the load is connected in series with the first resistor and the load is a constant current device; post-processing the first signal and outputting a second signal; and adjusting the output voltage based on the second signal to make the current flowing through the load constant. BRIEF DESCRIPTION OF THE DRAWINGS

[0006] This specification will be further described in the form of exemplary embodiments, which will be described in detail by the accompanying drawings. These embodiments are not restrictive, and in these embodiments, the same number represents the same structure, wherein:

[0007] Figure 1 is an exemplary circuit diagram of a constant current circuit based on a DC-DC converter according to some embodiments of this specification;

[0008] Figure 2 is an exemplary flow chart of a control method of a constant current circuit based on a DC-DC converter according to some embodiments of this specification;

[0009] Figure 3 is an exemplary flow chart of adjusting the pulse width of a first signal according to some embodiments of this specification;

[0010] Figure 4 is an exemplary flow chart of iteratively updating the pulse width of a first signal according to some embodiments of this specification;

[0011] Figure numerals: 110 - control system device, 111 - voltage acquisition port, 112 - control output port, 120 - post-processing module, 130 - DC-DC converter, 131 - power input port, 132 - power output port, 133 - signal feedback input port, 140 - load, 150 - voltage divider loop, GND - power ground. DETAILED DESCRIPTION

[0012] In order to more clearly illustrate the technical solutions of the embodiments of this specification, the following is a brief introduction to the drawings required for the description of the embodiments. Obviously, the drawings described below are only some examples or embodiments of this specification. For ordinary technicians in this field, this specification can also be applied to other similar scenarios based on these drawings without creative work. Unless it is obvious from the language environment or otherwise explained, the same reference numerals in the figures represent the same structure or operation.

[0013] It should be understood that the "system", "device", "unit" and / or "module" used herein are a method for distinguishing different components, elements, parts, portions or assemblies at different levels. However, if other words can achieve the same purpose, the words can be replaced by other expressions.

[0014] As shown in this specification and claims, unless the context clearly indicates an exception, the words "a", "an", "an" and / or "the" do not refer to the singular and may also include the plural. Generally speaking, the terms "comprise" and "include" only indicate the inclusion of the steps and elements that have been clearly identified, and these steps and elements do not constitute an exclusive list. The method or device may also include other steps or elements.

[0015] Flowcharts are used in this specification to illustrate the operations performed by the system according to the embodiments of this specification. It should be understood that the preceding or following operations are not necessarily performed precisely in order. Instead, the steps may be processed in reverse order or simultaneously. At the same time, other operations may also be added to these processes, or one or more operations may be removed from these processes.

[0016] In some embodiments, if a constant voltage is output to the load only through a DC-DC converter, the resistance of each device in the circuit will change during operation, causing the current flowing through the load to change, and the constant current effect cannot be achieved. In some embodiments, if the temperature characteristics of each device in the circuit are good, the resistance will not change too much, and the constant current effect can be achieved. However, when the load is switched, the current flowing through the load will change with the change of the load resistance. When using different loads, the circuit cannot output the same current.

[0017] Therefore, some embodiments of the present specification propose a constant current circuit based on a DC-DC converter, which controls the output voltage of the DC-DC converter by inputting a control signal into the DC-DC converter, and can achieve a constant current effect when switching different loads.

[0018] Figure 1 1 is an exemplary circuit diagram of a constant current circuit based on a DC-DC converter according to some embodiments of the present specification. A constant current circuit based on a DC-DC converter (hereinafter referred to as circuit 100). In some embodiments, Figure 1 As shown, the circuit 100 includes a control system device 110 , a post-processing module 120 , a DC-DC converter 130 and a load 140 .

[0019] The control system device 110 refers to a device for generating a control signal. For example, the control system device 110 may be a microcontroller unit (MCU).

[0020] In some embodiments, the control system device 110 may include a voltage collection port 111 and a control output port 112 .

[0021] In some embodiments, the voltage collection port 111 is connected to a loop connected to the load 140 and is configured to collect a first voltage value generated on the first resistor R211 by the current flowing through the load 140. Figure 1 As shown, the external power supply, the DC-DC converter 130, the load 140, the resistor R210, the first resistor R211, and the GND (power ground) are connected in sequence to form a complete current loop, wherein the resistor R210 is used to limit the current in the current loop. The voltage acquisition port 111 is connected to point a on the current loop through R212 and is configured to collect the voltage at point a, i.e., the first voltage value. Among them, R212 is used to limit the current of the input voltage acquisition port 111.

[0022] In some embodiments, in order to achieve constant current output of the DC-DC converter 130, it is necessary to monitor the current flowing through the load 140 in real time. However, the voltage acquisition port 111 cannot directly acquire the current, and it is necessary to first acquire the first voltage value, and then determine the current flowing through the load 140 based on the first voltage value. For example, since the first resistor R211 is connected to GND, and the first resistor R211 is connected in series with the load 140, the first voltage value is the voltage generated on the first resistor R211 by the current flowing through the load 140. Knowing the resistance value of the first resistor R211 and the first voltage value, the current flowing through the load 140 can be calculated by Ohm's law.

[0023] In some embodiments, the control output port 112 and the input end ( Figure 1 b) and is configured to output a first signal, which may be a PWM signal.

[0024] In some embodiments, the control system device 110 may be configured to generate and output a first signal based on the first voltage value.

[0025] In some embodiments, the control system device 110 can calculate the current flowing through the load 140 based on the first voltage value, and adjust the pulse width of the first signal based on the current flowing through the load 140 and the standard current. For example, when the current flowing through the load 140 is less than the standard current and the current difference is greater than a preset current threshold, the pulse width of the first signal is increased, and when the current flowing through the load 140 is greater than the standard current and the current difference is greater than the preset current threshold, the pulse width of the first signal is reduced. The standard current can be set by the user.

[0026] In some embodiments, the control system device 110 can also be configured to determine the measured voltage value at the current moment based on the first voltage value, and in response to the measured voltage value and the standard voltage value satisfying the preset difference condition, adjust the pulse width of the first signal so that the future voltage value at the future moment and the standard voltage value do not satisfy the preset difference condition. For more information, see Figure 3 Related instructions.

[0027] like Figure 1 As shown, the input end of the post-processing module 120 is connected to the control output port 112, and is configured to post-process the first signal and output a second signal. The post-processing includes but is not limited to at least one of filtering, current limiting, etc.

[0028] In some embodiments, the post-processing module 120 includes a second resistor ( R121 and R122 ), a first capacitor C123 , a diode group D124 , and the like.

[0029] In some embodiments, the second resistor may be configured to limit the current of the first signal. For example, after the first signal flows through the second resistor, the current generated by the first signal will decrease, thereby achieving current limiting of the first signal.

[0030] In some embodiments, the first capacitor C123 can be configured to filter the first signal. For example, one end of the first capacitor C123 is connected to GND, and when the first signal reaches the other end of the first capacitor C123, the high-frequency noise in the first signal is introduced into GND through the first capacitor C123, thereby filtering the first signal.

[0031] In some embodiments, filtering the first signal may also be achieved through other active or passive filtering circuits, which is not limited in this specification.

[0032] In some embodiments, the diode group D124 can be configured to achieve unidirectional communication of signals. For example, when a signal reaches the input end of the diode group D124, only the forward signal can pass through the diode group D124, thereby achieving unidirectional communication of signals.

[0033] In some embodiments of the present specification, the purity and stability of the PWM signal can be ensured by current limiting and filtering the first signal. By using the diode group D124, the PWM signal can be smoothly transmitted to the DC-DC converter 130 without being interfered by other signals, thereby enhancing the stability and reliability of the entire circuit.

[0034] In some embodiments, the output terminal ( Figure 1The second signal is connected to the signal feedback input port 133 of the DC-DC converter 130 through R213, and the second signal is transmitted to the DC-DC converter 130. In some embodiments, the circuit 100 further includes C214, and R213 and C214 are used to filter the input of the signal feedback input port 133.

[0035] The DC-DC converter 130 refers to a device that converts a DC voltage input into another DC voltage output, and is used to supply power to the load 140 .

[0036] In some embodiments, the DC-DC converter 130 may be configured to adjust the output voltage of the power outlet 132 based on the second signal to keep the current flowing through the load 140 constant. In some embodiments, the DC-DC converter 130 may include multiple models, such as TPS54331.

[0037] In some embodiments, the output voltage is positively correlated with the pulse width of the second signal, and the larger the pulse width of the second signal, the higher the output voltage. When the current flowing through the load 140 fluctuates, the control system device 110 can adjust the pulse width of the first signal in real time, and the second signal has the same pulse width as the first signal, so the output voltage also changes accordingly, so that the current flowing through the load 140 is constant.

[0038] In some embodiments, the DC-DC converter 130 may include a power input port 131 , a power output port 132 , and a signal feedback input port 133 .

[0039] In some embodiments, the power input port 131 is connected to an external power source and is configured to provide an input voltage.

[0040] In some embodiments, the power outlet 132 is connected to the load 140 and is configured to supply power to the load 140 .

[0041] In some embodiments, the signal feedback input port 133 is connected to the output end of the post-processing module 120 and is configured to receive a second signal output by the post-processing module 120 .

[0042] In some embodiments, the output voltage of the power outlet 132 is related to the second signal. The DC-DC converter 130 can adjust the output voltage of the power outlet 132 based on the second signal. For more information on how to adjust the output voltage based on the second signal, see Figure 2 Related instructions.

[0043] In some embodiments, the circuit 100 further includes a voltage divider loop 150 , and the signal feedback input port 133 is connected to the power output port 132 via the voltage divider loop 150 .

[0044] The voltage divider circuit is configured to adjust the initial output voltage of the power output port 132, such as Figure 1 As shown, the voltage divider circuit includes R151 and R152, and by adjusting the resistance values ​​of R151 and R152, the initial output voltage of the power output port 132 can be adjusted. For example, the larger the ratio of R151 to R152, the larger the initial output voltage of the power output port 132.

[0045] In some embodiments, when the circuit 100 includes a voltage divider circuit 150, the output terminal of the post-processing module 120 is connected to the Figure 1 The second signal is connected to point d in the middle, and the voltage at point d is superimposed on the second signal as the input signal of the signal feedback input port 133. The DC-DC converter 130 can adjust the output voltage of the power output port 132 based on the superimposed signal.

[0046] The load 140 is an electronic component in the circuit 100 for converting electrical energy into other forms of energy. For example, electronic components such as resistors, diodes, or any combination thereof. In some embodiments, the load 140 may include a constant current device. A constant current device refers to a device that needs to maintain a constant current during operation, such as a light emitting diode. The greater the current of the light emitting diode, the greater the brightness. In order to ensure constant brightness, it is necessary to ensure that the current flowing through the light emitting diode is constant.

[0047] In some embodiments, when the circuit 100 is started, the DC-DC converter 130 outputs a constant DC voltage, the control system device 110 collects a first voltage value in real time, and determines whether the current flowing through the load 140 is constant based on the first voltage value. When the current flowing through the load 140 is significantly different from the standard current, the control system device 110 adjusts the pulse width of the first signal, and the post-processing module 120 post-processes the first signal to obtain a second signal. The second signal is input into the DC-DC converter 130 as a control signal, and the DC-DC converter 130 adjusts the output voltage based on the pulse width of the second signal to make the current flowing through the load 140 constant.

[0048] In some embodiments of the present specification, a control system device is used to output a control signal, and the output voltage of the DC-DC converter is adjusted based on the control signal to provide a constant current to the load. Compared with directly using a constant current device, this can effectively reduce costs and has high flexibility of use.

[0049] It should be understood that the above description of the circuit 100 is only for convenience of description and does not limit the present specification to the scope of the embodiments. It is understood that, after understanding the principle of the system, those skilled in the art may modify the circuit 100 without deviating from the principle. For example, in some embodiments, the circuit 100 may include multiple voltage sampling circuits for collecting voltages at various locations in the circuit 100. Such variations are within the scope of protection of the present specification.

[0050] Figure 2 is an exemplary flow chart of a control method of a constant current circuit based on a DC-DC converter according to some embodiments of the present specification.

[0051] In some embodiments, the method includes: based on a control system device, collecting a first voltage value generated on a first resistor by the current flowing through the load; based on the first voltage value, generating and outputting a first signal, wherein the load is connected in series with the first resistor and the load is a constant current device; post-processing the first signal and outputting a second signal; based on the second signal, adjusting the output voltage so that the current flowing through the load is constant.

[0052] like Figure 2 As shown, the process 200 of the control method of the constant current circuit based on the DC-DC converter includes the following steps.

[0053] Step 210: Based on the control system device, a first voltage value generated by the current flowing through the load on the first resistor is collected. For more information about the control system device, the load and the first resistor, see Figure 1 Related instructions.

[0054] The first voltage value refers to the voltage generated on the first resistor. In some embodiments, the first voltage value can be obtained based on the voltage acquisition port of the control system device. For more description of the voltage acquisition port, see Figure 1 Related instructions.

[0055] In some embodiments, the first voltage value is proportional to the current flowing through the load. For example, the first voltage value collected by the voltage collection port of the control system device is the voltage drop generated on the first resistor, and the first resistor is unchanged, that is, it is equivalent to obtaining the current value flowing through the first resistor, and the current value is equal to the current value of the current flowing through the load. The voltage value collected by the voltage collection port actually reflects the current flowing through the load.

[0056] Step 220: Generate and output a first signal based on the first voltage value.

[0057] The first signal refers to a digital signal generated by a control system device based on a first voltage value. In some embodiments, the first signal may be a pulse width modulation (PWM) signal of a preset pulse width, etc. Pulse width refers to the duration of a pulse signal in the first signal. The duty cycle of the first signal (i.e., the ratio of the high level time to the total cycle time) can be used to control the output voltage of the DC-DC converter. In some embodiments of the present specification, the pulse width of the first signal is adjusted according to the first voltage value to keep the current flowing through the load constant.

[0058] In some embodiments, generating and outputting the first signal based on the first voltage value may be performed by a control output port of a control system device. For more information, see Figure 1 Related instructions.

[0059] In some embodiments, the control output port can determine the measured voltage value at the current moment based on the first voltage value; in response to the measured voltage value and the standard voltage value satisfying the preset difference condition, the pulse width of the first signal is adjusted so that the future voltage value at the future moment and the standard voltage value do not satisfy the preset difference condition. For more information, please refer to Figure 3 Related description.

[0060] Step 230: post-process the first signal and output a second signal.

[0061] The second signal refers to a digital signal generated after the post-processing module performs filtering, current limiting and other processing on the first signal. In some embodiments, the second signal can be a PWM signal with a preset pulse width, etc. For more information about the second signal, see Figure 1 Related description.

[0062] Post-processing refers to filtering, current limiting, one-way communication, etc. of the received first signal. In some embodiments, the post-processing can be performed by a post-processing module. For more information about post-processing, see Figure 1 Related instructions.

[0063] Step 240: Based on the second signal, adjust the output voltage to make the current flowing through the load constant.

[0064] Output voltage refers to the voltage output from the power output port of the DC-DC converter. For more information about output voltage, see Figure 1 Related description.

[0065] In some embodiments, the second signal is input to the DC-DC converter through the signal feedback input port, and the output voltage of the power output port of the DC-DC converter can be adjusted by adjusting the pulse width of the second signal. For more information on adjusting the output voltage based on the second signal, see Figure 1 Related instructions.

[0066] Figure 3 is an exemplary flow chart of adjusting the pulse width of the first signal according to some embodiments of the present specification.

[0067] In some embodiments, the control system device can determine the measured voltage value at the current moment based on the first voltage value; in response to the measured voltage value and the standard voltage value satisfying a preset difference condition, the pulse width of the first signal is adjusted so that the future voltage value at a future moment and the standard voltage value do not satisfy the preset difference condition.

[0068] like Figure 3 As shown, the process 300 of adjusting the pulse width of the first signal includes the following steps. In some embodiments, the process 300 is executed by a control system device.

[0069] Step 310: Determine the actual voltage value at the current moment based on the first voltage value.

[0070] The measured voltage value refers to the voltage value generated by the first resistor actually measured at the current moment. For more information about the first resistor, see Figure 1 Related description.

[0071] In some embodiments, the control system device can determine the measured voltage value in a variety of ways. For example, the control system device can directly determine the first voltage value actually measured at the current moment as the measured voltage value. At the current moment, the voltage acquisition port 111 acquires the voltage at point a, that is, the measured voltage value. For relevant descriptions of the voltage acquisition port 111, point a, etc., see Figure 1 Related description.

[0072] In some embodiments, the control system device may determine the measured voltage value based on a preset number of first voltage values ​​collected continuously.

[0073] Continuous acquisition refers to continuous detection within a period of time, for example, continuous acquisition within 100ms.

[0074] The preset number refers to the preset number of first voltage values ​​that need to be collected.

[0075] In some embodiments, the preset number can be determined based on a variety of methods. For example, the preset number can be determined by manual input, or can be preset based on experience.

[0076] In some embodiments, in response to the load being a light emitting diode, the preset number is related to the brightness adjustment range of the load. The control system device can determine the initial preset number and the correction factor based on the circuit noise level and the load parameter; and determine the preset number based on the initial preset number, the correction factor and the brightness adjustment range.

[0077] The initial preset quantity is an initial value of the preset quantity.

[0078] In some embodiments, the user can adjust the brightness of the LED. The brightness adjustment amplitude refers to the brightness difference of the LED before and after the adjustment. For example, the brightness adjustment amplitude is the absolute value of the brightness difference of the LED before and after the adjustment.

[0079] In some embodiments, the brightness of the light-emitting diode can be divided into different levels, and the user can switch between different levels by pressing a button. At this time, the brightness adjustment range can be expressed as the absolute value of the difference between the levels before and after the switch. When the user presses a button of a different level, a corresponding electrical signal is generated and sent to the control system device, and the control system device can determine the brightness adjustment range based on the electrical signal.

[0080] The user may also change the brightness of the light emitting diode in other ways, and accordingly, the brightness adjustment range may be expressed in other ways.

[0081] In some embodiments, the preset number is positively correlated with the brightness adjustment amplitude. The larger the brightness adjustment amplitude, the more drastic the change in the current, and the more drastic the change in the collected first voltage value. In order to make the measured voltage value determined based on the first voltage value closer to the actual voltage value of the first resistor, the measured voltage value can be determined based on the first voltage values ​​continuously collected over a longer period of time (i.e., more preset numbers of first voltage values).

[0082] The correction coefficient refers to a coefficient that can reflect the degree of influence of the brightness adjustment range on the preset number. When the initial preset number and the brightness adjustment range remain unchanged, the larger the correction coefficient, the larger the preset number.

[0083] The circuit noise level refers to a parameter that reflects the size of the noise in the circuit. The circuit noise includes at least one of thermal noise, shot noise, etc. Each circuit corresponds to a different circuit noise level. In some embodiments, the manufacturer can determine the circuit noise level of each circuit through experiments before the circuit leaves the factory. For example, the frequency domain distribution of the signal in the circuit can be analyzed by a spectrum analyzer, etc. to obtain the circuit noise level.

[0084] Load parameters refer to parameters related to the load. For example, the load parameters may include at least one of the brightness, color, expected life, rated voltage and rated current of the light-emitting diode. In some embodiments, the load parameters can be obtained by querying the data sheet of the load and stored in the control system device.

[0085] In some embodiments, the control system device may construct a first feature vector based on the circuit noise level and the load parameter, and send the first feature vector to an external processing device.

[0086] In some embodiments, an external processing device can construct a first reference vector library based on historical circuit noise levels and historical load parameters of historical circuits that meet first preset conditions in historical data. The first reference vector library includes multiple first reference vectors and corresponding reference preset quantities and reference correction coefficients.

[0087] The elements of each first reference vector include historical circuit noise levels and historical load parameters. The external processing device can determine the historical preset number and historical correction coefficient used by the historical circuit that meets the first preset condition as the reference preset number and reference correction coefficient corresponding to the first reference vector. Among them, the first preset condition includes but is not limited to the time point when the brightness of the light-emitting diode of the historical circuit is adjusted based on the historical brightness adjustment amplitude, and the time interval between the time point until the measured voltage value and the standard voltage value do not meet the preset difference condition is not greater than the preset duration, and the preset duration can be set manually. For more information about the preset difference condition, see below.

[0088] Common external processing devices include but are not limited to various computers, processors, etc. The external processing devices can be connected to the control system device through a hardware interface (for example, SPI, UART, etc.) and write data into the control system device through a compiler.

[0089] In some embodiments, the external processing device can search the first reference vector library based on the first feature vector, determine the first reference vector closest to the first feature vector, determine the reference preset quantity and reference correction coefficient corresponding to the first reference vector as the initial preset quantity and correction coefficient and store them in the control system device. The vector distance includes but is not limited to Euclidean distance, cosine distance, etc.

[0090] In some embodiments, the initial preset number and the correction factor are also related to the circuit response time, and the external processing device can determine the initial preset number and the correction factor based on the circuit noise level, the circuit response time and the load parameter by a method similar to the above-mentioned determination of the initial preset number and the correction factor based on the circuit noise level and the load parameter. At this time, the elements of each first reference vector in the first reference vector library also include the historical circuit response time.

[0091] The circuit response time refers to the response time of different components in the circuit, such as the response time of the DC-DC converter, the response time of the post-processing module, etc. The circuit response time can reflect the processing speed and sensitivity of different components in the circuit. The longer the circuit response time is, in order to obtain a more accurate measured voltage value, it is necessary to determine the measured voltage value based on the first voltage value of a longer time period. A longer time period means more first voltage values. Therefore, the initial preset number is positively correlated with the circuit response time.

[0092] In some embodiments, a worker may observe the input and output waveforms of each component in the circuit through an oscilloscope, and measure the circuit response time, etc.

[0093] In some embodiments, the control system device can adjust the initial preset number based on the correction coefficient and the brightness adjustment range to calculate the preset number. For example, the control system device can calculate the preset number using the following formula (1): N p =N pi +n×A l (1)

[0094] Among them, N p is the preset number, N pi is the initial preset number, n is the correction coefficient, A l Adjust the brightness.

[0095] In some embodiments of this specification, by adjusting the preset number according to the brightness adjustment amplitude, the measurement accuracy can be improved. A larger preset number helps to more accurately capture the change in voltage when the brightness changes greatly. By obtaining the circuit noise level experimentally before leaving the factory and determining the initial preset number and correction factor based on this, the demand for high computing power can be reduced, further reducing production costs. By considering factors such as circuit noise level and circuit response time, it is possible to adapt to different circuits, which helps to ensure that the circuit can maintain good performance under various conditions.

[0096] In some embodiments, the measured voltage value can be determined based on a variety of methods. For example, multiple voltage detections can be performed, and the first voltage values ​​detected multiple times can be averaged, and the average value obtained can be determined as the measured voltage value. Exemplarily, a preset number (such as 100 times, etc.) of first voltage values ​​are continuously detected within 100 ms, and the average value is calculated, and the average value obtained is determined as the measured voltage value.

[0097] In some embodiments of the present specification, since a single voltage detection may be affected by noise and other interference in the circuit, this may cause inaccurate measurement results, and instantaneous voltage fluctuations in the circuit may also cause a single measurement result to deviate from the actual value, the brightness adjustment of the light-emitting diode may involve dynamic adjustment of circuit parameters, and the control system device may take a certain amount of time to reach a new stable state. At this time, the fluctuations in the circuit are relatively large. Therefore, by determining the measured voltage value through a preset number of first voltage values ​​collected continuously, the accuracy of the determined voltage value can be improved, and the impact of instantaneous voltage fluctuations can be reduced, so as to ensure that the control system device can quickly and accurately adjust the pulse width of the first signal.

[0098] Step 320 , in response to the actual measured voltage value and the standard voltage value satisfying a preset difference condition, adjusting the pulse width of the first signal so that the future voltage value at a future moment and the standard voltage value do not satisfy the preset difference condition.

[0099] The standard voltage value refers to an ideal value or a preset value of the first voltage value. In some embodiments, the standard voltage value can be preset.

[0100] The preset difference condition refers to a condition under which the pulse width of the first signal needs to be adjusted. For example, the preset difference condition is that the measured voltage value is different from the standard voltage value.

[0101] The future time refers to a time adjacent to the time at which the pulse width of the first signal is adjusted.

[0102] The future voltage value refers to the voltage value generated by the first resistor collected at a future moment.

[0103] In some embodiments, in response to the measured voltage value and the standard voltage value satisfying a preset difference condition, the control system device can adjust the pulse width of the first signal in a variety of ways. For example, when the measured voltage value and the standard voltage value do not satisfy the preset difference condition, the pulse width of the first signal can be continuously adjusted by one or more feedbacks until the measured voltage value and the standard voltage value do not satisfy the preset difference condition. Feedback continuous adjustment refers to the process of making one or more adjustments, and making the next adjustment based on the feedback of the previous adjustment. Feedback continuous adjustment is to gradually adjust the pulse width of the first signal by a certain amount, and continue to make the next adjustment based on the continuous feedback.

[0104] Exemplarily, when the first voltage value continues to be the measured voltage value a0, and the control system device continues to transmit the first signal of the preset pulse width, at time t0, the detected measured voltage value becomes a1 (a1 and the standard voltage value meet the preset difference condition). The control system device can continuously adjust the pulse width of the first signal through feedback one or more times, continuously generate the first signal based on the adjusted pulse width, and continuously monitor the measured voltage value at multiple future moments until a pulse width that can stabilize the measured voltage value at a0 (meeting the preset difference condition) is determined, and the first signal is continuously generated based on the adjusted pulse width, thereby stabilizing the measured voltage value.

[0105] The pulse width adjustment can be preset based on experience. For example, a fixed amount can be adjusted each time, and the adjustment is continued until the measured voltage value and the standard voltage value do not meet the preset difference condition. Exemplarily, the pulse width of the first signal can be raised or lowered by a fixed amount each time. The fixed amount can be preset according to actual needs.

[0106] In some embodiments, the measured voltage value and the standard voltage value satisfy the preset difference condition including that the absolute value of the difference between the measured voltage value and the standard voltage value is greater than a preset threshold. The control system device can adjust the initial preset threshold based on the ambient temperature data, and determine the preset threshold based on the adjusted initial preset threshold.

[0107] The preset threshold refers to the maximum value of the absolute value of the difference between the measured voltage value and the standard voltage value when the pulse width of the first signal may not be adjusted. The preset threshold may be set manually.

[0108] The initial preset threshold refers to the initial setting value of the preset threshold.

[0109] The ambient temperature data refers to data related to the temperature of the working environment of the circuit. In some embodiments, the ambient temperature data can be obtained by installing a temperature sensor in the working environment of the circuit to measure.

[0110] Circuit component parameters refer to the parameters of other components in the circuit except the load, such as the resistance of a resistor, the capacitance of a capacitor, etc.

[0111] In some embodiments, the circuit element parameters can be obtained by querying a data sheet of the circuit element, etc., and stored in the control system device.

[0112] In some embodiments, the control system device may construct a second feature vector based on the load parameters and the circuit element parameters and store the second feature vector in the control system device.

[0113] In some embodiments, an external processing device can construct a second reference vector library based on historical load parameters and historical circuit element parameters of historical circuits that meet second preset conditions in historical data. The second reference vector library contains multiple second reference vectors and corresponding reference preset thresholds, and each element of the second reference vector includes historical load parameters and historical circuit element parameters.

[0114] The external processing device may determine the historical preset threshold used by the historical circuit that meets the second preset condition as the reference preset threshold corresponding to the second reference vector. The second preset condition includes but is not limited to the time point when the brightness of the light-emitting diode of the historical circuit is adjusted based on the historical brightness adjustment amplitude, and the time interval between the time point until the measured voltage value and the standard voltage value do not meet the preset difference condition is not greater than the preset time length.

[0115] In some embodiments, the external processing device can search the second reference vector library based on the second feature vector, determine the second reference vector that is closest to the second feature vector, determine the reference preset threshold corresponding to the second reference vector as the initial preset threshold and store it in the control system device.

[0116] In some embodiments, the ambient temperature may affect the performance of each component in the circuit. When the ambient temperature is too high, the performance of the component may deteriorate. At this time, the initial preset threshold value needs to be lowered to improve the stability of the circuit. Therefore, the control system device may adjust the initial preset threshold value based on the ambient temperature data to determine the preset threshold value. For example, when the ambient temperature data is higher than the preset temperature threshold value, the control system device may lower the initial preset threshold value, and the reduction in the initial preset threshold value is positively correlated with the ambient temperature data.

[0117] In some embodiments of this specification, by predetermining the initial preset threshold based on load parameters and circuit element parameters before the circuit leaves the factory and storing it in the control system device, it is possible to ensure that the circuit can remain stable under different working conditions. By monitoring the ambient temperature and adjusting the preset threshold in real time, it is helpful to more accurately adjust the preset threshold when the ambient temperature changes, thereby ensuring the safety of circuit power use and improving the responsiveness of the system.

[0118] In some embodiments of the present specification, when the measured voltage value deviates from the standard voltage value, the control method of the constant current circuit based on the DC-DC converter can dynamically adjust the pulse width of the first signal to restore the measured voltage value to the standard voltage value. This dynamic adjustment capability allows the constant current circuit to respond to changes in the internal resistance of the light-emitting diode or changes in environmental conditions, thereby maintaining current stability and ensuring that the light-emitting diode can output at a stable brightness.

[0119] In some embodiments, adjusting the pulse width of the first signal includes iteratively updating the pulse width of the first signal. For more information, see Figure 4 Related description.

[0120] Figure 4 is an exemplary flow chart of iteratively updating the pulse width of a first signal according to some embodiments of the present specification.

[0121] In some embodiments, the pulse width of the first signal is adjusted, including iteratively updating the pulse width of the first signal, and the iterative update includes: in response to the measured voltage value and the standard voltage value not satisfying a preset difference condition, the pulse width of the first signal is not adjusted; in response to the measured voltage value and the standard voltage value satisfying a preset difference condition, iteratively determining and adjusting the pulse width of the first signal based on the measured voltage value and the standard voltage value.

[0122] like Figure 4 As shown, the process 400 of iteratively updating the pulse width of the first signal includes the following steps. In some embodiments, the process 400 can be performed by a control system device. For more information about the initial pulse width of the first signal, see Figure 3 And related instructions.

[0123] Step 410 , in response to the measured voltage value and the standard voltage value satisfying a preset difference condition, determining an initial pulse width of the first signal based on the measured voltage value.

[0124] For more information about measured voltage values, standard voltage values, and preset difference conditions, see Figure 3 and related instructions;

[0125] Step 420: Determine and adjust the pulse width of the first signal based on the measured voltage value and the standard voltage value.

[0126] Step 430, in response to the measured voltage value and the standard voltage value not satisfying the preset difference condition, the pulse width adjustment of the first signal is completed; in response to the measured voltage value and the standard voltage value satisfying the preset difference condition, step 420 is repeated to iteratively determine and adjust the pulse width of the first signal until the iteration stop condition is satisfied.

[0127] The iteration stop condition may include multiple conditions, for example, the iteration stop condition is that the measured voltage value and the standard voltage value do not meet the preset difference condition. For another example, the iteration stop condition is that the number of iterations meets the iteration number threshold, the iteration result converges, etc. The iteration number threshold can be preset.

[0128] In some embodiments, the control system device may estimate the size of the current load resistance based on the measured voltage value, and determine the initial pulse width of the first signal based on the size of the load resistance.

[0129] In some embodiments, the load resistance can be expressed as a function related to the measured voltage value, the resistance value of the first resistor R211, the output voltage of the DC-DC converter, etc., as shown in function (2): R l =f(aV 211 ,bR 211 ,cV out ) (2)

[0130] Among them, R l is the size of the load resistance, V 211 is the measured voltage value, R 211 is the resistance value of the first resistor R211, V out is the output voltage of the DC-DC converter.

[0131] In some embodiments, the coefficients a, b, and c in function (2) may be determined by data fitting, and the fitting method includes but is not limited to the least square method, polynomial fitting, etc. The coefficients a, b, and c in the above function (2) are only examples, and the coefficients in function (2) may include multiple different coefficients.

[0132] In some embodiments, before the circuit leaves the factory, the staff may conduct multiple power-on experiments, collect the size of the load resistance, the measured voltage value, the resistance value of the first resistor R211, and the output voltage of the DC-DC converter in each experiment, determine the coefficients in function (2) through data fitting, and store function (2) in the control system device.

[0133] In some embodiments, the control system device can determine the initial pulse width of the first signal by querying the first preset table based on the size of the load resistance. The first preset table contains the corresponding relationship between load resistances of different sizes and initial pulse widths, which can be determined based on experiments. For example, in the above data fitting process, the staff can synchronously collect the pulse width that makes the measured voltage value and the standard voltage value not meet the preset difference condition, and determine the pulse width as the initial pulse width corresponding to the load resistance.

[0134] In some embodiments, the control system device can use the initial pulse width as the iteration starting point, determine the pulse width adjustment amount of the first signal based on the difference between the measured voltage value and the standard voltage value, and superimpose the pulse width adjustment amount on the pulse width of the first signal determined in the previous round of iteration to obtain the pulse width of the first signal determined in this round of iteration.

[0135] The pulse width adjustment amount is related to the difference between the measured voltage value and the standard voltage value. For example, the greater the absolute value of the difference, the greater the pulse width adjustment amount. When the difference is positive, the pulse width of the first signal needs to be reduced, and when the difference is negative, the pulse width of the first signal needs to be increased.

[0136] In some embodiments, in response to the measured voltage value and the standard voltage value satisfying a preset difference condition, the control system device may determine the pulse width of the first signal by the following formula (3): W new =W old -η×(V 211 -V s ) (3)

[0137] Among them, W new The pulse width of the first signal determined in the current round of iteration; W old is the pulse width of the first signal determined in the previous iteration. In the first iteration, W old is the iteration starting point, i.e. the initial pulse width; V 211 is the measured voltage value obtained by the current round of iteration calculation; V s is the standard voltage value; η is the learning rate, which is a small positive number that determines the step size of each iterative adjustment and can be set manually.

[0138] In some embodiments, taking the iteration stop condition that the measured voltage value and the standard voltage value do not meet the preset difference condition as an example, after the current round of iteration, the control system device can determine whether the measured voltage value and the standard voltage value meet the preset difference condition after the current round of iteration. If the measured voltage value and the standard voltage value do not meet the preset difference condition, the pulse width adjustment of the first signal is completed and the iteration ends. If the measured voltage value and the standard voltage meet the preset difference condition, the control system device can substitute the pulse width of the first signal of the current round into the above formula (3) as W in formula (3) old , re-determine the pulse width W of the first signal determined in the current round of iteration new , W new The pulse width of the first signal is used as the pulse width of the first signal determined in the next round of iteration, and the next round of iteration is continued until the measured voltage value and the standard voltage value do not meet the preset difference condition.

[0139] In some embodiments of the present specification, by timely adjusting the pulse width of the first signal to maintain a constant current, the risk of LED overheating can be reduced, which helps to improve the safety and reliability of the system. The initial pulse width is determined based on the measured voltage value. This initial pulse width based on the current state helps the system approach the target state faster during subsequent iterative adjustments. Relying on a closed-loop feedback mechanism, the pulse width of the first signal is continuously iteratively adjusted according to the difference between the measured voltage value and the standard voltage value, which can adjust the output voltage more accurately and quickly, and help the circuit remain stable under any circumstances.

[0140] The basic concepts have been described above. Obviously, for those skilled in the art, the above detailed disclosure is only for example and does not constitute a limitation of this specification. Although not explicitly stated here, those skilled in the art may make various modifications, improvements and corrections to this specification. Such modifications, improvements and corrections are suggested in this specification, so such modifications, improvements and corrections still belong to the spirit and scope of the exemplary embodiments of this specification.

[0141] At the same time, this specification uses specific words to describe the embodiments of this specification. For example, "one embodiment", "an embodiment", and / or "some embodiments" refer to a certain feature, structure or characteristic related to at least one embodiment of this specification. Therefore, it should be emphasized and noted that "one embodiment" or "an embodiment" or "an alternative embodiment" mentioned twice or more in different positions in this specification does not necessarily refer to the same embodiment. In addition, certain features, structures or characteristics in one or more embodiments of this specification can be appropriately combined.

[0142] In addition, unless explicitly stated in the claims, the order of the processing elements and sequences described in this specification, the use of alphanumeric characters, or the use of other names are not intended to limit the order of the processes and methods of this specification. Although the above disclosure discusses some invention embodiments that are currently considered useful through various examples, it should be understood that such details are only for illustrative purposes, and the attached claims are not limited to the disclosed embodiments. On the contrary, the claims are intended to cover all modifications and equivalent combinations that are consistent with the essence and scope of the embodiments of this specification. For example, although the system components described above can be implemented by hardware devices, they can also be implemented only by software solutions, such as installing the described system on an existing server or mobile device.

[0143] Similarly, it should be noted that in order to simplify the description disclosed in this specification and thus help understand one or more embodiments of the invention, in the above description of the embodiments of this specification, multiple features are sometimes combined into one embodiment, figure or description thereof. However, this disclosure method does not mean that the features required by the subject matter of this specification are more than the features mentioned in the claims. In fact, the features of the embodiments are less than all the features of the single embodiment disclosed above.

[0144] In some embodiments, numbers describing the number of components and attributes are used. It should be understood that such numbers used in the description of the embodiments are modified by the modifiers "about", "approximately" or "substantially" in some examples. Unless otherwise specified, "about", "approximately" or "substantially" indicate that the numbers are allowed to vary by ±20%. Accordingly, in some embodiments, the numerical parameters used in the specification and claims are approximate values, which may change according to the required features of individual embodiments. In some embodiments, the numerical parameters should take into account the specified significant digits and adopt the general method of retaining digits. Although the numerical domains and parameters used to confirm the breadth of their range in some embodiments of this specification are approximate values, in specific embodiments, the setting of such numerical values ​​is as accurate as possible within the feasible range.

[0145] Each patent, patent application, patent application publication, and other materials, such as articles, books, specifications, publications, documents, etc., cited in this specification are hereby incorporated by reference in their entirety. Except for application history documents that are inconsistent with or conflicting with the contents of this specification, documents that limit the broadest scope of the claims of this specification (currently or later attached to this specification) are also excluded. It should be noted that if the descriptions, definitions, and / or use of terms in the materials attached to this specification are inconsistent or conflicting with the contents described in this specification, the descriptions, definitions, and / or use of terms in this specification shall prevail.

[0146] Finally, it should be understood that the embodiments described in this specification are only used to illustrate the principles of the embodiments of this specification. Other variations may also fall within the scope of this specification. Therefore, as an example and not a limitation, alternative configurations of the embodiments of this specification may be considered consistent with the teachings of this specification. Accordingly, the embodiments of this specification are not limited to the embodiments explicitly introduced and described in this specification.

Claims

1. A constant current circuit based on a DC-DC converter, characterized in that: The circuit comprises: A control system device, the control system device comprising a voltage acquisition port and a control output port; the voltage acquisition port is connected to a loop connected to a load, and is configured to acquire a first voltage value generated on a first resistor by a current flowing through the load; the control output port is configured to generate and output a first signal based on the first voltage value, wherein the load is connected in series with the first resistor, and the load is a constant current device; a post-processing module, configured to perform post-processing on the first signal and output a second signal; A DC-DC converter, the DC-DC converter comprising a power input port, a power output port and a signal feedback input port; the power input port is connected to an external power supply, the power output port is connected to the load, the signal feedback input port is connected to the power output port via a voltage divider loop, the signal feedback input port is also connected to the post-processing module, and is configured to receive the second signal output by the post-processing module; the DC-DC converter is configured to adjust the output voltage of the power output port based on the second signal so that the current flowing through the load is constant.

2. The circuit according to claim 1, characterized in that The control system device is further configured as follows: Based on the first voltage value, determining the actual voltage value at the current moment; In response to the measured voltage value and the standard voltage value satisfying a preset difference condition, the pulse width of the first signal is adjusted so that a future voltage value at a future moment and the standard voltage value do not satisfy the preset difference condition.

3. The circuit according to claim 2, characterized in that The measured voltage value is determined based on a preset number of first voltage values ​​that are continuously collected.

4. The circuit according to claim 2, characterized in that In response to the load being a light emitting diode, the standard voltage value is determined based on a required brightness of the load.

5. The circuit according to claim 1, characterized in that The post-processing module comprises: a second resistor, configured to limit the current of the first signal; a first capacitor, configured to filter the first signal; The diode group is configured to achieve unidirectional communication of signals.

6. A control method for a constant current circuit based on a DC-DC converter, characterized in that: The method comprises: Based on the control system device, a first voltage value generated on the first resistor by the current flowing through the load is collected; Based on the first voltage value, generating and outputting a first signal, wherein the load is connected in series with the first resistor, and the load is a constant current device; Post-processing the first signal to output a second signal; Based on the second signal, the output voltage is adjusted to make the current flowing through the load constant.

7. The method according to claim 6, characterized in that The method further comprises: Based on the first voltage value, determining the actual voltage value at the current moment; In response to the measured voltage value and the standard voltage value satisfying a preset difference condition, the pulse width of the first signal is adjusted so that a future voltage value at a future moment and the standard voltage value do not satisfy the preset difference condition.

8. The method according to claim 7, characterized in that The measured voltage value is determined based on a preset number of first voltage values ​​that are continuously collected.

9. The method according to claim 7, characterized in that In response to the load being a light emitting diode, the standard voltage value is determined based on a required brightness of the load.

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