A lighted suture driver, control system, and control method

Abstract

This invention discloses a light-emitting stitching driver, control system, and control method. The driver includes a voltage regulation unit, an inverter unit, and a control unit. The voltage regulation unit adopts a PWM-to-DAC feedback mechanism, whereby the PWM signal output by the microcontroller is filtered by RC and fed back to the FB pin of the DC-DC chip to achieve continuous voltage regulation. The inverter unit uses a center-tapped transformer and a dual MOSFET topology. The control unit outputs a 100kHz carrier SPWM signal, and the frequency step adjustment from 200Hz to 2.5kHz is achieved by changing the number of sampling points in the half-cycle of the sine wave. This invention simplifies the circuit structure, reduces costs, and realizes digital dimming and frequency modulation, making it suitable for automotive interior ambient lighting.

Description

Technical Field

[0001] This invention belongs to the field of LED lighting driver technology, specifically relating to a light-emitting stitch driver, control system and control method based on SPWM control, so as to realize efficient, wide-bandwidth and digital dimming and frequency modulation of automotive interior ambient lighting. Background Technology

[0002] Traditional driving methods often employ power supply structures using industrial frequency transformers or high-frequency transformers, which suffer from problems such as large size, low efficiency, and limited dimming methods. Especially for special applications requiring wide voltage input, high-precision voltage regulation, and wide bandwidth (200Hz-2.5kHz) adjustment, existing technologies struggle to simultaneously meet the requirements of high efficiency, low cost, and miniaturization.

[0003] Specifically, the existing technology has the following main drawbacks: Large size and low efficiency: Low-frequency power frequency solutions directly use 50Hz power frequency transformers to step up the voltage. The structure is simple but the size is huge, which cannot meet the miniaturization requirements of modern decorative lighting; the efficiency of power frequency transformers is usually less than 85%, resulting in large energy loss.

[0004] Limited frequency adjustment range: Traditional inverters use a fixed frequency design, which has a narrow frequency adjustment range and cannot cover the mid-frequency application scenarios of 200Hz-2.5kHz, making it difficult to achieve dynamic lighting effects such as flowing water and breathing.

[0005] Complex circuitry and high cost: Most solutions rely on full-bridge inverter circuits to generate SPWM waves, requiring 4 switching transistors and LC filter circuits, resulting in complex circuitry, high cost, and difficult debugging; the number of components is large, leading to a high failure rate.

[0006] Low dimming accuracy and poor control coordination: Analog dimming methods suffer from low accuracy and slow response. More critically, in existing solutions, the dimming circuit and frequency modulation circuit usually operate separately, resulting in a time lag after receiving commands. This leads to asynchronous changes in brightness and frequency, resulting in harsh and unnatural dynamic lighting effects. It is difficult to achieve smooth, advanced dynamic effects such as welcoming or breathing effects, and it also cannot work efficiently with the vehicle's intelligent cockpit system.

[0007] Therefore, providing a low-power intermediate frequency inverter driver based on SPWM control that can achieve digital dimming and frequency modulation, simplify circuit structure, and reduce system cost is a technical problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0008] To address the aforementioned technical problems, this invention provides an SPWM-based luminous stitch driver, control system, and control method to overcome the technical shortcomings of existing technologies, such as large size, limited frequency adjustment range, complex circuitry, and high cost.

[0009] This invention achieves efficient, wide-bandwidth, and digital light-emitting slit drive by constructing a dual-core driver architecture of "DC-DC digital voltage regulation" and "medium-frequency SPWM inverter".

[0010] The system adopts a modular architecture, consisting of a voltage regulation unit, an inverter unit, and a control unit. The modules work together to form a complete closed-loop system.

[0011] Specifically, this invention selects a DC-DC chip that supports FB feedback. A closed-loop control is achieved by generating an analog voltage through an RC low-pass filter via the PWM output of a microcontroller and feeding it back to the FB pin, enabling continuous adjustment from 0-5V. An SPWM signal with a carrier frequency of 100kHz is generated by the microcontroller, and two N-channel MOSFETs drive a center-tapped transformer. A timer interrupt controls the number of sine wave sampling points, achieving frequency step adjustment within the range of 200Hz-2.5kHz.

[0012] Thus, this invention achieves a complete closed loop from voltage regulation to inverter output to frequency control, significantly improving the efficiency, flexibility and digitalization level of the light-emitting suture drive.

[0013] According to one aspect of the present invention, a light-emitting suture driver is provided, comprising: Voltage regulation unit for outputting adjustable DC voltage; An inverter unit, connected to the output terminal of the voltage regulation unit, is used to invert the adjustable DC voltage into AC voltage. A control unit is connected to the voltage regulation unit and the inverter unit respectively. The control unit is configured to synchronously control the amplitude of the adjustable DC voltage output by the voltage regulation unit and the frequency of the AC voltage output by the inverter unit according to the received instructions.

[0014] Preferably, the voltage regulation unit includes: a DC-DC chip with a feedback pin; a first PWM signal source connected to the feedback pin; and a filter circuit connected between the first PWM signal source and the feedback pin; the PWM signal output by the first PWM signal source is processed by the filter circuit and then input to the feedback pin to regulate the output voltage of the DC-DC chip.

[0015] Preferably, the filtering circuit is an RC low-pass filter circuit.

[0016] Preferably, the inverter unit includes: a transformer having a primary side; two switching transistors respectively connected to the two ends of the primary side of the transformer for controlling the current direction of the primary side; and a drive circuit connected between the control unit and the two switching transistors for driving the two switching transistors to conduct alternately according to the SPWM signal output by the control unit.

[0017] Preferably, the transformer is a center-tapped transformer, with a center tap, a first terminal, and a second terminal on its primary side. The center tap is connected to the output terminal of the voltage regulation unit, and the first terminal and the second terminal are respectively connected to the two switching transistors.

[0018] Preferably, the two switching transistors are N-channel MOSFETs.

[0019] Preferably, the driving circuit is a totem pole circuit.

[0020] Preferably, the control unit includes: a second PWM signal source for outputting an SPWM signal to the inverter unit; and a frequency adjustment module for adjusting the modulation waveform of the SPWM signal by changing the number of sampling points within a half-cycle of the sine wave, thereby changing the frequency of the AC voltage.

[0021] Preferably, the carrier frequency of the SPWM signal is 100kHz, and the frequency of the AC voltage is adjustable in the range of 200Hz to 2.5kHz.

[0022] Preferably, the control unit is connected to the host computer via a communication bus, receives dimming and frequency modulation commands from the host computer, and synchronously adjusts the amplitude of the adjustable DC voltage and the frequency of the AC voltage according to the commands.

[0023] Preferably, the communication bus is a LIN bus or a CAN bus.

[0024] In another aspect, the present invention provides a light-emitting suture control method based on SPWM control, applied to the light-emitting suture driver described in any of the above claims, comprising the following steps: The control unit outputs a first control signal to the voltage regulation unit to adjust the amplitude of the output voltage; The control unit outputs a second control signal to the inverter unit to adjust the frequency of the output voltage; The control unit adjusts the first control signal and the second control signal synchronously according to the received instructions to achieve coordinated control of the output voltage amplitude and frequency.

[0025] In another aspect, the present invention provides a light-emitting suture control system, comprising: A host computer sends dimming and frequency modulation commands via a bus; At least one light-emitting suture driver as described above, which, upon receiving the instruction, adjusts the adjustable DC voltage amplitude and AC voltage frequency of its output accordingly; At least one LED light-emitting thread is connected to the output terminal of the driver to receive the AC voltage output by the driver.

[0026] In another aspect of the present invention, an application of the luminous stitching driver described above in vehicle interior ambient lighting is provided.

[0027] This invention connects the voltage regulation unit and the inverter unit to the same control unit, and receives commands via the same bus to achieve synchronous control of both. This solves the problem of asynchronous response in existing technologies where dimming and frequency modulation are implemented by separate control circuits. In existing solutions, the dimming circuit and the frequency modulation circuit usually operate independently, resulting in a time difference after receiving commands, leading to asynchronous changes in brightness and frequency, and harsh dynamic effects. This invention generates both voltage-modulated PWM and frequency-modulated SPWM signals simultaneously through a single control unit, and updates parameters synchronously in the same timing interrupt, ensuring strict timing consistency between brightness and frequency changes and achieving smooth and natural dynamic lighting effects.

[0028] Compared with the prior art, the present invention has the following beneficial effects: Simplified circuitry and reduced costs: Eliminating the complex filtering and isolation circuits of traditional high-frequency solutions reduces the number of components by more than 30%, facilitating mass production. The use of a PWM-to-DAC mechanism replaces a dedicated DAC chip, resulting in an overall cost reduction of 40% compared to existing solutions.

[0029] Compact size and high efficiency: Utilizing mid-frequency SPWM inverter technology, the size is reduced by approximately 60% and efficiency is improved by over 15% compared to the power frequency transformer solution. The drive topology consisting of a center-tapped transformer and dual MOSFETs reduces the number of switching transistors by 50% compared to the full-bridge inverter solution, reducing circuit complexity while achieving full-bridge functionality.

[0030] High dimming and frequency modulation accuracy: The number of sine wave sampling points is controlled by a timer interrupt, enabling adjustable frequency steps with a frequency adjustment accuracy of ±1Hz. The PWM to DAC feedback mechanism enables continuous voltage regulation from 0-5V, resulting in high dimming accuracy and fast response speed.

[0031] Strong wideband adjustment capability: Supports frequency step adjustment within a wide bandwidth of 200Hz-2.5kHz to meet the needs of various dynamic lighting effects such as flowing water, breathing, and rhythm.

[0032] Highly intelligent with smooth dynamic effects: Supports LIN / CAN bus communication, simultaneously generating voltage-modulated PWM and frequency-modulated SPWM signals through a single control unit, and updating parameters synchronously in the same timing interrupt, ensuring strict timing consistency between brightness and frequency changes, achieving smooth and natural dynamic lighting effects. Compared to discrete control solutions, the response speed is improved by more than 50%, perfectly realizing complex lighting effects such as welcoming, breathing, and rhythmic effects. Attached Figure Description

[0033] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0034] Figure 1 This is a schematic diagram of the overall architecture of the light-emitting suture driver provided in an embodiment of the present invention, showing the three core modules of voltage regulation unit, inverter unit and control unit and their interrelationships; Figure 2 The circuit diagram of the voltage regulation unit provided in this embodiment of the invention shows the connection relationship between the PWM output of the microcontroller and the FB pin of the DC-DC chip after RC filtering. Figure 3 This is a schematic diagram of the SPWM modulation principle provided in an embodiment of the present invention, illustrating the modulation relationship between the sine wave and the PWM carrier. Figure 4 The schematic diagram of the inverter unit driving circuit provided in the embodiment of the present invention shows the topology of the totem pole circuit driving two MOSFETs connected to the center tap transformer; Figure 5a This is a schematic diagram of a 100kHz carrier PWM signal provided in an embodiment of the present invention; Figure 5b This is a schematic diagram of the modulated output sine wave waveform provided in an embodiment of the present invention; Figure 6 The control logic block diagram provided in this embodiment of the invention illustrates the connection relationship between the control unit and the host computer through a bus.

[0035] To facilitate understanding of the technical solution of this invention, some technical terms appearing in the specification are explained as follows: SPWM (Sinusoidal Pulse Width Modulation): A modulation technique that changes the width of the PWM pulse according to a sinusoidal pattern, thereby making the average value of the output voltage present as a sinusoidal waveform. This invention uses SPWM technology to control the output waveform of the inverter unit.

[0036] DAC (Digital-to-Analog Converter): An electronic device that converts digital signals into analog voltage or current. This invention replaces a standalone DAC chip with a PWM-to-DAC mechanism, reducing system costs.

[0037] PWM (Pulse Width Modulation): A modulation technique that controls the average output voltage by changing the pulse width, widely used in power electronics and motor control. In this invention, the PWM signal is used both for voltage regulation control of the voltage regulation unit and as the carrier signal for SPWM.

[0038] MOSFET (Metal-Oxide-Semiconductor Field-Effect Transistor): A voltage-controlled switching device with advantages of fast switching speed and low drive power, widely used in switching power supplies and inverter circuits. This invention uses an N-channel MOSFET as the switching transistor in the inverter unit.

[0039] LIN (Local Interconnect Network): A low-cost serial communication protocol primarily used in automotive body electronic control systems, such as for controlling modules like doors, seats, and sunroofs. This invention supports LIN bus communication to achieve data interaction with the vehicle's cockpit system.

[0040] CAN (Controller Area Network): A highly reliable serial communication protocol widely used in automotive electronic systems, supporting multi-master communication and real-time control. This invention allows for the selection of the CAN bus to achieve higher communication rates depending on application requirements.

[0041] RC low-pass filter circuit: A filter circuit composed of resistors and capacitors that can filter out high-frequency components in PWM signals and extract their DC components, realizing the conversion of PWM to analog voltage. This invention utilizes an RC low-pass filter circuit to convert PWM signals into DC voltage for regulating the output of a DC-DC chip.

[0042] Totem-pole circuit: A push-pull drive circuit consisting of two transistors (one NPN and one PNP, or two MOSFETs), which can provide a large drive current, eliminate crossover distortion, and improve switching speed and drive capability. This invention uses a totem-pole circuit to drive the MOSFET switching transistors of the inverter unit.

[0043] Center-tapped transformer: A transformer with a center tap on the primary side. The center tap is connected to the positive terminal of the power supply, and the two ends are connected to switching transistors, enabling double-ended push-pull operation and simplifying the drive circuit. This invention uses a center-tapped transformer, reducing the number of switching transistors by 50% compared to a full-bridge inverter scheme.

[0044] Carrier ratio: In SPWM modulation, the carrier frequency... With modulation wave frequency The ratio, that is This indicates the number of carrier cycles contained within one modulation wave cycle. This invention achieves this by changing the carrier ratio. To achieve output frequency adjustment.

[0045] Lookup table method: A method that pre-calculates and stores function values, and retrieves the required data by looking up a table during runtime. This invention uses the lookup table method to generate SPWM waveforms, pre-calculates the duty cycle of each sampling point of the sine wave and stores it in an array, and the controller periodically reads and updates the PWM duty cycle.

[0046] The terms used above are only for explaining specific embodiments of the present invention and are not intended to limit the scope of protection of the present invention. Those skilled in the art will understand that other existing technologies with the same or similar functions can be employed without departing from the concept of the present invention. Detailed Implementation

[0047] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0048] The embodiments of this invention are written in a progressive manner.

[0049] Example 1: System Architecture

[0050] like Figure 1 As shown, this invention provides a light-emitting suture driver, the core of which lies in establishing a collaborative working mechanism among voltage regulation, inverter output, and control unit to achieve digital dimming and frequency modulation. The system adopts a modular architecture, consisting of three core modules that work collaboratively to achieve a complete closed loop from voltage regulation to inverter output.

[0051] Specifically, the system includes the following functional modules: The voltage regulation unit is used to output an adjustable DC voltage. This unit includes a DC-DC chip, a microcontroller, and an RC filter circuit. The microcontroller acts as the first PWM signal source, outputting a PWM signal that is filtered by an RC low-pass filter to generate an analog voltage, which is then fed back to the FB pin of the DC-DC chip to achieve closed-loop control of the output voltage. The module's input is a DC power supply, and its output is a continuously adjustable DC voltage from 0-5V.

[0052] An inverter unit, connected to the output of the voltage regulation unit, is used to invert the adjustable DC voltage into AC voltage. This unit includes a center-tapped transformer, two N-channel MOSFETs, and a totem-pole driver circuit. The microcontroller acts as a second PWM signal source, outputting an SPWM signal that is amplified by the totem-pole circuit and then drives the two MOSFETs to alternately conduct, causing the center-tapped transformer to invert the DC voltage into an AC voltage output.

[0053] The control unit, connected to both the voltage regulation unit and the inverter unit, is used to synchronously control the amplitude of the adjustable DC voltage and the frequency of the AC voltage. This unit communicates with the host computer via the same bus, receives dimming and frequency modulation commands, and synchronously adjusts the duty cycle of the PWM signal and the modulation waveform of the SPWM signal according to the commands.

[0054] The three functional modules described above work together to form a complete closed-loop system. The user sends commands through the host computer, the control unit parses the commands and synchronously adjusts the output voltage of the voltage regulation unit and the output frequency of the inverter unit to achieve dynamic changes in light brightness and frequency.

[0055] All modules work together through well-defined circuit connections, ensuring the stability and reliability of the system.

[0056] Example 2: Specific Implementation of the Voltage Regulation Unit like Figure 2 As shown, this invention provides a specific circuit implementation of a voltage regulation unit. The voltage regulation unit uses a DC-DC chip that supports FB feedback. It generates an analog voltage through a microcontroller's PWM output, which is then filtered by an RC low-pass filter and fed back to the FB pin to achieve closed-loop control.

[0057] Specifically, the microcontroller outputs a 15kHz first PWM signal. This signal is filtered by an RC low-pass filter circuit (composed of resistors and capacitors) to generate a smooth analog voltage. To ensure good filtering performance, the PWM frequency should be at least 10 times the cutoff frequency of the RC filter. To improve accuracy, this design sets the RC cutoff frequency to 1 / 20 of the PWM frequency, i.e., 15000 / 20 = 750Hz. The cutoff frequency calculation formula is... ,get , The analog voltage is input to the feedback pin (FB pin) of the DC-DC chip and compared with the internal reference voltage of the DC-DC chip. The DC-DC chip adjusts its output voltage according to the comparison result so that the voltage at the FB pin is always equal to the internal reference voltage.

[0058] The output voltage VCC is divided by resistors R5, R11, and R12 to obtain the feedback voltage VFB, which is equal to the internal reference voltage of the DC-DC chip. By changing the duty cycle of the first PWM signal, the analog voltage value output after RC filtering can be changed, thereby changing the output voltage of the DC-DC chip and achieving continuous adjustment within the range of 0-5V.

[0059] This circuit structure replaces the traditional independent DAC chip solution, achieving precise digital voltage regulation while significantly simplifying the circuit structure and reducing system costs.

[0060] The reason for choosing 0-5V as the voltage regulation range is that the input voltage provided by automobiles is usually between 7-18V. The 0-5V range can ensure that the input voltage range is not affected by the input voltage, while being compatible with the typical voltage range of a 12V vehicle power system after DC-DC step-down.

[0061] Example 3: SPWM Modulation Principle This embodiment elaborates on the SPWM modulation principle. For example... Figure 3 As shown, a sinusoidal voltage is an analog quantity whose amplitude changes with time. By changing the duty cycle of the PWM wave according to a sinusoidal law, an equivalent sinusoidal wave can be modulated.

[0062] The SPWM generation of this invention employs a strategy of fixed carrier frequency and variable modulation frequency. The carrier frequency fc is fixed at 100kHz and is generated by the advanced timer of the control unit. The fundamental frequency of the output voltage... The fundamental frequency is determined by the frequency of the sinusoidal modulation wave. According to the SPWM principle, the fundamental frequency... The carrier frequency fc and the number of sampling points (i.e., carrier ratio N) within one sinusoidal period satisfy the following: Since fc is fixed, the output frequency can be precisely adjusted by changing N. For example, when When the frequency is 200Hz, N=500, meaning each fundamental frequency cycle contains 500 PWM pulses; when At 2500Hz, N=40 can still ensure sufficient harmonic suppression capability.

[0063] The specific implementation uses a lookup table method. The duty cycle value of each sampling point within a complete sine wave cycle is pre-calculated and stored in an array. The control unit uses a timer (modulation wave timer) to sequentially read the duty cycle value from the array at fixed time intervals and update it in the carrier PWM comparator register, thereby continuously outputting the SPWM waveform.

[0064] Example 4: Inverter Unit Drive Circuit like Figure 4 As shown, this invention provides a specific implementation of the inverter unit drive circuit. The circuit uses two N-channel MOSFETs (SDM56AG04LV; withstand voltage 40V, current 55A) to drive a center-tapped transformer (core model: EE22; primary winding 50 turns per side, wire diameter 0.3mm (AWG 31); secondary winding 3000 turns per side, wire diameter 0.125mm (AWG 34)). The drive circuit employs a totem-pole structure to enhance the driving capability of the SPWM wave.

[0065] The primary side of the center-tapped transformer has a center tap, a first terminal, and a second terminal. The center tap is connected to the output terminal (VCC) of the voltage regulation unit, the first terminal is connected to the drain of the first MOSFET (Q1), and the second terminal is connected to the drain of the second MOSFET (Q2). The sources of both MOSFETs are grounded.

[0066] The gates of the two MOSFETs are connected to the output terminals of the totem pole circuit. The totem pole circuit consists of two transistors (NPN transistor L8050PLT1G: 25V, 800mA and PNP transistor L8550HRLT1G 25V 800mA) forming a push-pull structure, which can provide a larger drive current and improve the switching speed.

[0067] The SPWM signal output by the microcontroller is amplified by a totem-pole circuit and drives two MOSFETs to conduct alternately. When Q1 is on and Q2 is off, current flows from VCC through the first terminal of the transformer primary winding to Q1 and then to ground; when Q1 is off and Q2 is on, current flows from VCC through the second terminal of the transformer primary winding to Q2 and then to ground. The alternating conduction of the two MOSFETs creates an alternating current on the primary winding of the transformer, inducing an AC voltage output on the secondary winding.

[0068] Compared to the full-bridge inverter scheme, the center-tap topology reduces the number of switching transistors by 50%, achieving full-bridge functionality while reducing circuit complexity and cost.

[0069] Example 5: SPWM signal waveform like Figure 5a , Figure 5b As shown, this invention provides a waveform diagram of an SPWM signal. Wherein: Figure 5aThis is a PWM signal with a carrier frequency of 100kHz generated by the microcontroller. This signal, acting as the carrier for SPWM modulation, has a fixed frequency and amplitude, with its duty cycle varying over time.

[0070] Figure 5b This is the sinusoidal waveform output from the secondary side of the transformer after SPWM modulation. This waveform is obtained by modulating the carrier signal with a sinusoidal duty cycle and then filtering it through the transformer.

[0071] In the specific implementation, the microcontroller controls the output of the sine wave sampling points through timer interrupts. Taking a 500Hz sine wave as an example, the sine wave period is 2ms, and half-period is 1ms. If the carrier frequency is 100kHz and the period is 10μs, then half-period of the sine wave contains 100 carrier cycles. Therefore, the half-period of the sine wave is divided into 100 segments for sampling, each segment corresponding to a PWM pulse, and its duty cycle is determined according to the amplitude of that segment of the sine wave. Thus, a complete sine wave cycle requires 200 samples. The duty cycle corresponding to each sampling point is calculated using a sine table generation function.

[0072] Define an array of sine tables, for example: #define SIN_TABLE_SIZE 200 uint16_t sin_table[SIN_TABLE_SIZE]; Calculate the duty cycle at each point:

[0073]

[0074]

[0075]

[0076]

[0077] By using a timer interrupt, the duty cycle value of each sampling point is read sequentially from the lookup table, and the PWM comparator register is updated, so that the SPWM waveform can be continuously output. After passing through the transformer, a smooth sine wave is obtained on the secondary side.

[0078] Example 6: Frequency Adjustment Principle Combination Figure 5a and Figure 5b The present invention achieves output frequency adjustment by changing the number of sampling points within half a cycle of a sine wave.

[0079] As shown in Example 5, the output sine wave frequency fsine is determined by the following formula: ; in: This is the sine table update frequency (i.e., the modulation wave timer interrupt frequency). The number of sampling points within a complete sine wave cycle; Dual-timer collaborative architecture: TIM1 (Carrier Generator): Generates a 100kHz high-frequency PWM, which determines the switching frequency.

[0080] TIM2 (Modulation Wave Timer): Configure 100kHz=10 Trigger an interrupt or DMA to control the sine table update rhythm and determine the output frequency.

[0081] The principle of frequency modulation can be summarized as: Sine wave frequency = carrier frequency / (2 × number of half-cycle sampling points). When the carrier frequency is fixed at 100kHz, the number of half-cycle sampling points decreases from 250 to 20, and the corresponding output frequency increases from 200Hz to 2.5kHz.

[0082] 200Hz was chosen as the lower frequency limit because flickering light below 200Hz is perceptible to the human eye and can cause discomfort. 2.5kHz was chosen as the upper frequency limit because MOSFET switching losses increase significantly above 2.5kHz, exceeding the range of human visual persistence. The carrier frequency of 100kHz was chosen after considering both switching losses and waveform quality—too low a frequency would cause output waveform distortion, while too high a frequency would increase switching losses.

[0083] Example 7: Control Logic and Cooperative Control like Figure 6 As shown, this invention provides a control logic block diagram for a control unit. The control unit is connected to a host computer via a communication bus, receives dimming commands and frequency modulation commands, and synchronously adjusts the amplitude of the output voltage and the frequency of the output AC voltage according to the commands.

[0084] Specifically, the control unit includes a microcontroller and a communication interface. The microcontroller communicates with the host computer via a LIN bus and parses the received instructions. The dimming instruction is used to change the duty cycle of the first PWM signal, thereby adjusting the output voltage of the voltage regulation unit; the frequency modulation instruction is used to change the number of sampling points of the SPWM signal, thereby adjusting the output frequency of the inverter unit.

[0085] The core of the control unit lies in coordinated control: when it receives a command that simultaneously includes dimming and frequency modulation, the microcontroller synchronously adjusts the duty cycle of the first PWM signal and the number of sampling points of the second PWM signal to achieve linked changes in the output voltage amplitude and output frequency. For example, in welcome mode, the brightness of the lights gradually increases while the frequency changes from slow to fast, creating a dynamic lighting effect.

[0086] Example 8: Protection Mechanism and Parameter Estimation To ensure the safety and reliability of system operation, the control unit of this invention also integrates an intelligent protection mechanism and an output parameter estimation function.

[0087] 1. Output parameter estimation: To avoid the safety risks and increased costs associated with direct sampling at the high-voltage output terminal, this invention uses an indirect calculation method to estimate the output voltage and current.

[0088] Output voltage estimation: by detecting the peak value of the primary voltage of the transformer. And by combining the transformer turns ratio and system efficiency, the output voltage is estimated. The calculation formula is: ,in The number of turns of the secondary coil. The number of turns of the primary coil. The overall system efficiency is approximately 0.85, including rectification, core, and copper losses.

[0089] Output current estimation: A sampling resistor is connected in series in the primary circuit of the transformer, and the primary current is detected by a differential amplifier circuit. Then, based on the turns ratio, the output current is estimated by converting it to the secondary winding. According to the transformer principle, the primary current and secondary current satisfy an inverse ratio of turns. Considering system efficiency, the calculation formula is as follows: .in The number of turns of the secondary coil. The number of turns of the primary coil. For the overall system efficiency (≈0.85, including rectification, core, and copper losses), the calibration points are: the efficiency coefficient needs to be calibrated under no-load and full-load conditions. This compensates for the voltage drop of the rectifier diode (≈0.7V×2) and the nonlinearity of the magnetic core.

[0090] 2. Protection Mechanism Design: Based on the estimated output parameters, the control unit can monitor the system's operating status in real time and execute the following protection actions: Overload protection: When the estimated output power If the power exceeds 1.2 times the rated power for more than 2 seconds, the control unit determines it as an overload and executes power reduction or delayed shutdown protection.

[0091] Short circuit protection: When the estimated output current When the current instantaneously exceeds 1.5 times the rated current, the control unit immediately blocks the drive signal of the inverter unit and cuts off the output, thus effectively protecting the driver and the load.

[0092] Through the above protection mechanism, the driver of the present invention can respond quickly and accurately when faced with abnormal operating conditions, which greatly improves the safety and reliability of the system.

[0093] Example 9: Application of Ambient Lighting in Car Interiors Combination Figures 1 to 4 , Figure 5a , Figure 5b , Figure 6 Taking a car manufacturer's intelligent cockpit lighting system as an example, the company uses the system of this invention to control the interior ambient lighting.

[0094] System configuration phase (corresponding) Figure 1 A car manufacturer has integrated the driver of this invention into its smart cockpit system. Based on vehicle configuration requirements, the system configures driver parameters for different loads such as front cabin ambient lighting, door panel ambient lighting, and footwell lights. Each driver connects to the cockpit domain controller via a LIN bus, receiving unified dimming and frequency modulation commands.

[0095] Voltage regulation applications (corresponding) Figure 2 The ambient lighting controller needs to switch brightness levels according to the driving mode. Lower brightness is required in comfort mode, while higher brightness is needed in sport mode. The microcontroller changes the duty cycle of the first PWM signal based on the dimming command sent by the host computer. For example, if a lower brightness is needed, the microcontroller decreases the PWM duty cycle. After RC filtering, the analog voltage input to the FB pin of the DC-DC chip decreases, and the output voltage of the DC-DC chip decreases accordingly, thus reducing the brightness of the light-emitting lines. Conversely, increasing the PWM duty cycle increases the brightness. In this way, continuous brightness adjustment within the 0-5V range is achieved without the need for a separate DAC chip, simplifying the circuit structure.

[0096] Frequency adjustment application (combined) Figure 3 , Figure 5a , Figure 5b To achieve a flowing dynamic lighting effect, the flashing frequency of the lights needs to be changed. The microcontroller, based on the frequency modulation command sent by the host computer, changes the number of sampling points within a half-cycle of the sine wave. Assuming a 500Hz output frequency is needed, the microcontroller sets the number of sampling points per half-cycle to 100, with each sampling point corresponding to a timer interrupt and outputting a PWM pulse. 100 PWM pulses constitute half a sine wave, and 200 pulses constitute a complete cycle with a period of 2ms, corresponding to a frequency of 500Hz. When switching to 1kHz is required, the microcontroller adjusts the number of sampling points per half-cycle to 50, with 100 pulses constituting a complete cycle with a period of 1ms, corresponding to a frequency of 1kHz. In this way, the frequency can be stepped and adjustable within the range of 200Hz to 2.5kHz, supporting various dynamic lighting effects such as flowing, breathing, and rhythmic effects.

[0097] Inverter drive applications (corresponding) Figure 4 The SPWM signal output by the microcontroller is amplified by the totem-pole circuit and drives two MOSFETs to conduct alternately. The center-tapped transformer inverts the DC voltage output by the DC-DC unit into AC voltage, which is then output to the luminous stitching load.

[0098] Collaborative control applications (corresponding) Figure 6 In welcome mode, the host computer simultaneously sends dimming and frequency modulation commands. Upon receiving the commands, the microcontroller synchronously adjusts the duty cycle of the first PWM signal and the number of sampling points of the second PWM signal. For example, this allows the light brightness to gradually increase while the frequency changes from slow to fast, creating a warm and welcoming atmosphere.

[0099] The control unit communicates with the host computer via a LIN bus. LIN bus is a commonly used low-cost serial communication protocol in automobiles and can meet the needs of vehicle electronic control. For scenarios requiring higher communication speeds, a CAN bus can be used.

[0100] Technical Performance Verification: Actual testing has verified that, compared to traditional power frequency transformer solutions, the present invention, employing medium-frequency SPWM inverter technology, reduces transformer size by approximately 60% and improves efficiency by over 15%. Compared to full-bridge inverter solutions, the center-tapped topology reduces the number of switching transistors by 50%, the total number of components by over 30%, and lowers BOM costs by approximately 40%. Frequency regulation accuracy reaches ±1Hz, and command response time is shortened to within 50ms, improving response speed by over 50%.

[0101] This invention is applicable not only to automotive interior ambient lighting, but also to LED lighting scenarios that require dynamic dimming and frequency modulation, such as architectural decorative lighting, landscape lighting, and stage lighting, and has broad application prospects.

[0102] Example 10: Illuminated Thread Control System The present invention also provides a light-emitting suture control system, including a host computer, at least one light-emitting suture driver and at least one LED light-emitting suture.

[0103] The host computer connects to each driver via a LIN bus or CAN bus, sending dimming and frequency modulation commands. The host computer can be a vehicle cockpit domain controller, a lighting control module, or a dedicated lighting control panel.

[0104] After receiving a command, the driver adjusts the adjustable DC voltage amplitude and AC voltage frequency accordingly. Multiple drivers can be connected in parallel on the same bus to receive the same command for synchronous control, or to receive different commands for independent control.

[0105] The LED light-emitting threads are connected to the output of the driver, receiving the AC voltage output by the driver. By coordinating the control of the output voltage and frequency of each driver, various dynamic lighting effects such as breathing lights and rhythmic lights can be achieved to meet the atmosphere creation needs of different scenarios.

[0106] Alternative solutions Regarding the technical solution of this invention, the following alternative solutions also achieve the basic function, but each has its own drawbacks: Single-ended transformer solution: Replace the three-terminal center-tapped transformer with a single-ended transformer. This solution requires the addition of a magnetic reset circuit (such as an RCD snubber circuit or additional windings), increasing circuit complexity and reducing efficiency by approximately 5-8 percentage points. Furthermore, the transformer utilization rate is low, making it unsuitable for wideband operation from 200Hz to 2.5kHz.

[0107] Full-bridge inverter solution: This solution uses four switching transistors to form a full-bridge inverter, requiring a high-end drive circuit and a complex LC filter circuit. This solution has a large number of components, high cost, and a complex SPWM control algorithm, making it difficult to debug and unsuitable for cost-sensitive automotive applications.

[0108] Analog PWM scheme: This scheme uses an analog comparator and a triangular wave generator to generate PWM signals. However, this scheme suffers from large temperature drift, low accuracy, difficulty in achieving precise digital dimming and frequency modulation, and inability to communicate with LIN / CAN buses, thus failing to meet the digital requirements of smart cockpits.

[0109] While the above alternatives can achieve the basic functions, they are not as good as the preferred solution of the present invention in terms of cost, efficiency, control precision, or level of intelligence.

[0110] One or more embodiments in this application are intended to cover all such substitutions, modifications, and variations that fall within the broad scope of this application. Therefore, any omissions, modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of one or more embodiments in this application should be included within the protection scope of this application.

[0111] The foregoing has provided a detailed description of an SPWM-based luminous stitch driver, control system, and control method. The above description of the disclosed embodiments enables those skilled in the art to implement or use this application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this application. Therefore, this application is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A light-emitting suture driver, characterized in that, include: Voltage regulation unit for outputting adjustable DC voltage; An inverter unit, connected to the output terminal of the voltage regulation unit, is used to invert the adjustable DC voltage into AC voltage. The control unit is connected to the voltage regulation unit and the inverter unit respectively, and is used to synchronously control the amplitude of the adjustable DC voltage and the frequency of the AC voltage.

2. The light-emitting suture driver according to claim 1, characterized in that, The voltage regulation unit includes: DC-DC chip with feedback pin; The first PWM signal source is connected to the feedback pin; A filter circuit is connected between the first PWM signal source and the feedback pin; The PWM signal output from the first PWM signal source is processed by the filter circuit and then input to the feedback pin to adjust the output voltage of the DC-DC chip.

3. The light-emitting suture driver according to claim 1, characterized in that, The inverter unit includes: A transformer has a primary side; Two switching transistors are connected to the two ends of the primary side of the transformer, respectively, to control the direction of the current in the primary side; A drive circuit is connected between the control unit and the two switching transistors, and is used to drive the two switching transistors to turn on alternately according to the SPWM signal output by the control unit.

4. The light-emitting suture driver according to claim 3, characterized in that, The transformer is a center-tapped transformer, with a center tap, a first terminal, and a second terminal on its primary side. The center tap is connected to the output terminal of the voltage regulation unit, and the first terminal and the second terminal are respectively connected to the two switching transistors.

5. The light-emitting suture driver according to claim 1, characterized in that, The control unit includes: The second PWM signal source is used to output the SPWM signal to the inverter unit; The frequency adjustment module is used to adjust the modulation waveform of the SPWM signal by changing the number of sampling points within a half-cycle of the sine wave, thereby changing the frequency of the AC voltage.

6. The light-emitting suture driver according to claim 5, characterized in that, The carrier frequency of the SPWM signal is 100kHz, and the frequency of the AC voltage is adjustable in the range of 200Hz to 2.5kHz.

7. The light-emitting suture driver according to claim 1, characterized in that, The control unit is connected to the host computer via a communication bus, receives dimming and frequency modulation commands from the host computer, and synchronously adjusts the amplitude of the adjustable DC voltage and the frequency of the AC voltage according to the commands.

8. A method for controlling luminous sutures based on SPWM control, applied to the luminous suture driver according to any one of claims 1 to 7, characterized in that, Includes the following steps: The control unit outputs a first control signal to the voltage regulation unit to adjust the amplitude of the output voltage; The control unit outputs a second control signal to the inverter unit to adjust the frequency of the output voltage; The control unit adjusts the first control signal and the second control signal synchronously according to the received instructions to achieve coordinated control of the output voltage amplitude and frequency.

9. A light-emitting suture control system, characterized in that, include: A host computer sends dimming and frequency modulation commands via a bus; At least one light-emitting suture driver as described in any one of claims 1 to 7, wherein after receiving the instruction, the driver adjusts the adjustable DC voltage amplitude and AC voltage frequency of the output accordingly; At least one LED light-emitting thread is connected to the output terminal of the driver to receive the AC voltage output by the driver.

10. The application of a light-emitting stitching actuator as described in any one of claims 1 to 7 in a vehicle interior ambient light, characterized in that, The amplitude and frequency of the luminous suture are synchronously adjusted by the driver.

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