A PWM control signal transmission method and system

Abstract

The present invention provides a PWM control signal transmission method and system, the method comprising: a main controller generates a control signal and a corresponding check signal according to current and voltage sampling signals; the control signal and the check signal are superimposed by amplitude modulation or phase modulation to obtain a composite signal; the composite signal is transmitted to each DAB module through a communication bus; the DAB module demodulates the composite signal to separate the control signal and the check signal, and detects the integrity and correctness of the control signal according to the check signal. This solution can reduce the communication delay and noise interference effects existing in the control signal transmission, ensure the accuracy and reliability of the control signal, and realize the real-time and accurate transmission of multi-module DAB control signals.

Description

Technical Field

[0001] The present invention belongs to the field of communication technology, and in particular relates to a PWM control signal transmission method and system. Background Art

[0002] Dual Active Bridge (DAB) converters have been widely used in modern power electronics systems due to their high efficiency, bidirectional power flow, and modular design, especially in electric vehicle charging stations, distributed energy systems, and grid energy storage. The ability of DAB converters to flexibly adjust under different loads and power requirements makes them ideal for efficient energy transmission and management. As the application of multi-module DAB systems gradually expands, the complexity of the system and the challenges of communication control also increase. In a multi-module parallel structure, each module needs to be closely coordinated to ensure the overall power transmission efficiency and stability of the system. However, communication between modules is often susceptible to electromagnetic interference (EMI), noise, and other external environmental factors, resulting in errors or delays in signal transmission. Such communication errors may cause power imbalance, response lag, and even serious degradation of system performance in some cases.

[0003] In a multi-module system, how to ensure power balance among modules is a key issue. Without a reasonable balance control mechanism, some modules may run under overload while other modules are lightly loaded or idle, which reduces the overall efficiency of the system and increases the risk of module failure. Currently, advanced control strategies, such as power balance compensation algorithms, have been applied in multi-module DAB systems. Such algorithms achieve uniform power distribution and optimize the dynamic performance and overall energy efficiency of the system by dynamically adjusting the power output of each module. In addition, the use of multi-module parallel technology can achieve joint control while ensuring the independence of each module, greatly improving the redundancy and reliability of the system and increasing the flexibility of the system.

[0004] However, despite the progress made by these multi-module technologies in improving system performance, traditional multi-module DAB system communications, such as using CAN bus, are still affected by communication delays and noise interference, resulting in unreliable control signals. Especially in the high-frequency environment of power electronics, signal transmission may not be timely and accurate due to noise and delay. Summary of the invention

[0005] In view of this, an embodiment of the present invention provides a PWM control signal transmission method and system for solving the problem that current control signal transmission is unreliable and signal transmission may not be timely and accurately transmitted due to noise and delay.

[0006] In a first aspect of an embodiment of the present invention, a PWM control signal transmission method is provided, comprising:

[0007] The main controller generates a control signal and a corresponding verification signal according to the current and voltage sampling signals;

[0008] The control signal and the verification signal are superimposed by amplitude modulation or phase modulation to obtain a composite signal;

[0009] Transmitting the integrated signal to each DAB module via a communication bus;

[0010] The DAB module demodulates the integrated signal to separate the control signal and the check signal, and detects the integrity and correctness of the control signal according to the check signal.

[0011] In a second aspect of an embodiment of the present invention, a PWM control signal transmission system is provided, comprising:

[0012] A main controller is used to generate a control signal and a corresponding verification signal according to the current and voltage sampling signals; and to superimpose the control signal and the verification signal through amplitude modulation or phase modulation to obtain a comprehensive signal, and transmit the comprehensive signal to each DAB module through a communication bus;

[0013] The DAB module is used to demodulate the integrated signal to separate the control signal and the check signal, and detect the integrity and correctness of the control signal according to the check signal.

[0014] In the embodiment of the present invention, by introducing a control signal transmission method based on PWM signal superposition, the integrity and correctness of the control signal can be directly verified in the DAB module according to the check signal, thereby eliminating errors caused by communication delays and noise interference, ensuring the reliability of the control signal, achieving timely and accurate transmission of the control signal, and ensuring efficient communication and precise control of multiple DAB modules. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0016] Figure 1 A schematic flow chart of a PWM control signal transmission method provided by an embodiment of the present invention;

[0017] Figure 2 A schematic diagram of the structure of a multi-module DAB provided by an embodiment of the present invention;

[0018] Figure 3 A schematic diagram of the structure of a main controller and a sub-controller provided in one embodiment of the present invention;

[0019] Figure 4 A schematic diagram of signal synchronization provided by an embodiment of the present invention;

[0020] Figure 5 A schematic structural diagram of a PWM control signal transmission system provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0021] In order to make the purpose, features and advantages of the present invention more obvious and easy to understand, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the embodiments described below are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0022] It should be understood that the term "including" and other similar expressions in the specification or claims of the present invention and the above-mentioned drawings are intended to cover non-exclusive inclusions, such as a process, method, system, or device including a series of steps or units is not limited to the listed steps or units. In addition, "first" and "second" are used to distinguish different objects, not to describe a specific order.

[0023] See also Figure 1 , a flow chart of a PWM control signal transmission method provided by an embodiment of the present invention includes:

[0024] S101, the main controller generates a control signal and a corresponding verification signal according to the current and voltage sampling signals;

[0025] The main controller generates control signals for each DAB (Dual ActiveBridge, i.e., dual active bridge) module according to the current sampling signal and the voltage sampling signal in the system, so as to control each DAB module.

[0026] Wherein, the main controller includes a first DSP (Digital Signal Processor) chip, a second DSP chip and an FPGA controller;

[0027] The first DSP chip is used to sample the system voltage signal and current signal, and the second DSP chip is used to control the input current and output voltage of the primary and secondary H bridges in the DAB module, and to generate the modulation wave required by the primary and secondary H bridges and the phase shift value required by the DAB module.

[0028] The first DSP chip is not only responsible for the voltage and current sampling of the system, but also used for communication with the host computer, as well as system fault diagnosis and protection; the second DSP chip is responsible for controlling the input current and output voltage of the primary and secondary sides of the dual active bridge H-bridge (H-Bridge), generating the modulation wave required by HB (i.e. H-bridge) and the phase shift value required by DAB.

[0029] In some embodiments, the main controller is connected to the sub-controllers in each DAB module, such as Figure 2 As shown, each sub-controller includes a DSP controller and an FPGA controller. The sub-control DSP is responsible for the voltage and current sampling and protection of each DAB module, and the sub-control FPGA is responsible for the PWM pulse generation of each DAB module. The main controller includes a first DSP chip (i.e., DSP1), a second DSP chip (i.e., DSP2), and an FPGA chip.

[0030] The superimposed signal can be directly output by the second DSP in the main controller, and the output signal can be transmitted to the DSP chip of the DAB module sub-controller through the CAN bus, etc., to realize the control of the DAB module.

[0031] It can be understood that the sub-controller is located inside a single DAB module, and can be operated independently by a single module, and independently controlled according to the detected voltage and current. When multiple modules are running, the main controller controls each sub-controller, and the control signals of each sub-controller are sent uniformly by the main control circuit.

[0032] The control signal is used to control and adjust the phase shift angle, current and power of each DAB module, and the verification signal is used to verify the control signal and determine the integrity and accuracy of the control signal.

[0033] Wherein, the control signal includes a phase control signal, a power control signal and a current control signal;

[0034] The phase control signal is used to adjust the phase shift angle of each DAB module, the power control signal is used to adjust the power reference signal of each DAB module, and the current control signal is used to adjust the current distribution of each DAB module.

[0035] The phase shift angle of each DAB module is collected and calculated in real time, and the phase shift angles of different modules are coordinated using a superposition algorithm. The superposition control signal of the phase shift angle is adjusted in real time to ensure power transmission synchronization in the multi-module DAB system and reduce the risk of overload of a single module. Based on the power transmission requirements of multiple DAB modules, the power reference signal of each module is adjusted in real time. The controller will calculate the power difference of each module in real time and generate the corresponding power adjustment amount, and superimpose the power reference signal of each module to achieve balanced power transmission. The output of the current controller is adjusted in real time by collecting the current signal of each module. In the case of uneven current, the controller corrects and superimposes the current command of each module to ensure uniform current distribution of each module, thereby achieving optimal distribution of current in the overall system.

[0036] S102, superimposing the control signal and the verification signal through amplitude modulation or phase modulation to obtain a comprehensive signal;

[0037] Amplitude modulation carries information by changing the amplitude of the carrier signal, while phase modulation transmits information by changing the phase of the carrier. By changing the amplitude or phase of the carrier signal, the control signal and the check signal are superimposed, and the superimposed composite signal is transmitted to achieve the transmission of control information and check information.

[0038] S103, transmitting the integrated signal to each DAB module via a communication bus;

[0039] The integrated signal can be transmitted to each DAB module via CAN bus, optical fiber, etc.

[0040] In some embodiments, a partial circuit structure of a multi-module DAB is as follows Figure 3 As shown in the figure, each DAB module has the same structure and can include transistors Q1, Q2, Q3, Q4, Q5, Q6, Q7, Q8, diodes D1, D2, D3, D4, D5, D6, D7, D8, inductor L m , capacitor C s , C p , C f , and transformer T, etc.

[0041] S104, the DAB module demodulates the integrated signal to separate the control signal and the check signal, and detects the integrity and correctness of the control signal according to the check signal.

[0042] The DAB module separates the control signal and the check signal through the demodulator. The check signal is used to check the control signal and determine the integrity and correctness of the control signal. When the control signal is missing or wrong, a corresponding error correction prompt is generated.

[0043] In this embodiment, by superimposing the control signal and the test signal of the DAB module, the influence of communication delay and noise interference can be reduced, the accuracy and reliability of the control signal can be guaranteed, and efficient communication and precise control in the DAB multi-module system can be achieved.

[0044] In one embodiment, the main controller sends a synchronization signal and a control signal once in each control cycle. At the initial moment of sending the synchronization signal, the control signal is fixed to a low level and a verification signal is generated synchronously; wherein the switching signal frequency of the controller in the DAB module is set to an integer multiple of the synchronization signal frequency, and the control signal frequency is set to an integer multiple of the synchronization signal frequency.

[0045] The main controller sends waves in the form of Figure 4 As shown, a synchronization signal and a control signal are sent once in each control cycle, and the two are independent of each other. At the initial moment of sending the synchronization signal, the control signal is fixed at a low level, and the check signal starts to send waves synchronously, which eliminates the delay error of the synchronization signal in the communication transmission process and ensures that the time intervals of two adjacent synchronization signals are equal, thereby avoiding a large deviation between the actual value of the carrier counter and the synchronization point during carrier synchronization of DAB.

[0046] It should be understood that when performing carrier synchronization in a multi-module DAB (dual active bridge), in addition to eliminating the communication delay of the synchronization signal, it is also necessary to consider setting the synchronization frequency reasonably. If the time interval of carrier synchronization is too long, due to the deviation of the crystal oscillator clock of each unit, the deviation between the carrier counter of the DAB and the actual synchronization point during synchronization may increase, thereby causing changes in the phase shift value and duty cycle of the PWM pulse, and causing a sudden change in the DAB inductor current. Therefore, in theory, the synchronization frequency should be as high as possible, but if the synchronization frequency is set too high, it may cause the clock and data transmission of the control system to be disordered.

[0047] To this end, this embodiment proposes the following synchronization frequency setting principle: the switching frequency is an integer multiple of the synchronization frequency, thereby ensuring that the positions of all synchronization points are consistent during synchronization and avoiding synchronization deviation; the control frequency is an integer multiple of the synchronization frequency. This ensures that the synchronization signal transmission will not interfere with the system control structure, and there is no need to add additional clock signals, thereby ensuring the reliability of the control system.

[0048] For example, the switching frequency is 20kHz and the control frequency is 2kHz, so the carrier synchronization frequency is selected to be 2kHz, that is, the carrier signal of DAB is synchronized once every 10 switching cycles. During these 10 switching cycles, the crystal oscillator error of each sub-control FPGA is extremely small, and because the communication delay of the synchronization signal has been eliminated, the actual value of the carrier counter during carrier synchronization deviates very little from the synchronization point, and the phase shift value and duty cycle of the PWM pulse remain almost unchanged. At the same time, since the synchronization frequency is the same as the control frequency, there is no need to introduce an additional synchronization clock, which ensures that the control structure of the system is not affected and improves the stability and reliability of the digital control system.

[0049] In one embodiment, the DAB module feeds back the operation status information to the main controller via the state pointer, and the main controller adjusts the output of the control signal in real time according to the fed-back operation status information.

[0050] Each DAB module feeds back the equipment operation status to the main controller through the status pointer. The main controller adjusts the output of the control signal in real time according to the feedback information. The verification signal can ensure that the signal transmission is not distorted and prevent serious equipment failure.

[0051] In some embodiments, the sub-controller in the DAB module integrates power management, signal acquisition and processing, PWM signal control, and CAN communication functions. Through this sub-controller structure, voltage and current signals can be acquired and processed in real time, and PWM signals for driving external devices can be generated. At the same time, it can also communicate with other modules through the CAN bus. The sub-controller includes:

[0052] Auxiliary power supply, Vin on the left provides input voltage for the system. This voltage is stabilized by the auxiliary power supply and supplied to the FPGA module and drive circuit below to ensure the normal operation of the system.

[0053] The FPGA module is divided into an upper FPGA and a lower FPGA. The upper FPGA is responsible for outputting switching signals, including logic gates and other control signals. Its main function is to generate signals for driving circuits and send them to the driving circuits through PWM signals, thereby controlling external power devices. The lower FPGA contains a variety of functional modules.

[0054] The FPGA below includes: a Power module that provides operating voltage for the FPGA; a Timer module that is used for timing or periodic operations; an eCAN communication module that communicates with other modules or systems through the CAN bus to exchange data and control information; an ePWM module that generates pulse width modulation (PWM) signals; a GPIO module that is a general-purpose input and output interface that is used to communicate with external devices or detect status; an ADC module that is used to collect voltage (V) and current (I) signals sent by the conditioning circuit; a drive circuit that is used to receive PWM signals generated by the FPGA above and drive external devices, and that can convert the signals output by the FPGA into actual control signals to control the switching state of the power element; a conditioning circuit that is used to sample signals (V, I). The conditioning circuit is responsible for collecting voltage and current signals from the system's power elements or loads, and transmitting these signals back to the FPGA for sampling and monitoring through the ADC; a CAN communication module. The CAN communication in the system is used for data transmission and coordination between modules. In particular, in a multi-module system, real-time communication between multiple FPGA modules can be achieved through the CAN bus to ensure synchronous control and data sharing.

[0055] It should be understood that the sequence numbers of the steps in the above embodiments do not imply a sequence of execution, and the execution sequence of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present invention.

[0056] Figure 5 A schematic diagram of the structure of a PWM control signal transmission system provided by an embodiment of the present invention, the system comprising:

[0057] The main controller 510 is used to generate a control signal and a corresponding verification signal according to the current and voltage sampling signals; and to superimpose the control signal and the verification signal through amplitude modulation or phase modulation to obtain a comprehensive signal, and transmit the comprehensive signal to each DAB module through a communication bus;

[0058] The DAB module 520 is used to demodulate the integrated signal to separate the control signal and the check signal, and detect the integrity and correctness of the control signal according to the check signal.

[0059] Wherein, the main controller 510 includes a first DSP chip, a second DSP chip and an FPGA controller;

[0060] The first DSP chip is used to sample the system voltage signal and current signal, and the second DSP chip is used to control the input current and output voltage of the primary and secondary H bridges in the DAB module, and to generate the modulation wave required by the primary and secondary H bridges and the phase shift value required by the DAB module.

[0061] Wherein, the control signal includes a phase control signal, a power control signal and a current control signal;

[0062] The phase control signal is used to adjust the phase shift angle of each DAB module, the power control signal is used to adjust the power reference signal of each DAB module, and the current control signal is used to adjust the current distribution of each DAB module.

[0063] Preferably, the main controller 510 sends a synchronization signal and a control signal once in each control cycle, and at the initial moment of sending the synchronization signal, fixes the control signal to a low level and synchronously generates a verification signal;

[0064] The switching signal frequency of the controller in the DAB module is set to an integer multiple of the synchronization signal frequency, and the control signal frequency is set to an integer multiple of the synchronization signal frequency.

[0065] Optionally, the DAB module 520 is further used to feed back operation status information to the main controller via a status pointer;

[0066] Accordingly, the main controller 510 adjusts the output of the control signal in real time according to the operation status information fed back by the DAB module.

[0067] Those skilled in the art can clearly understand that, for the convenience and brevity of description, the specific working processes of the systems, devices and modules described above can refer to the corresponding processes in the aforementioned method embodiments and will not be repeated here.

[0068] In the above embodiments, the description of each embodiment has its own emphasis. For parts that are not described or recorded in detail in a certain embodiment, reference can be made to the relevant descriptions of other embodiments.

[0069] As described above, the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features thereof may be replaced by equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A PWM control signal transmission method, characterized in that: include: The main controller generates a control signal and a corresponding verification signal according to the current and voltage sampling signals; The main controller sends a synchronization signal and a control signal once in each control cycle. At the initial moment of sending the synchronization signal, the control signal is fixed to a low level and a verification signal is generated synchronously. The switching signal frequency of the controller in the DAB module is set to an integer multiple of the synchronization signal frequency, and the control signal frequency is set to an integer multiple of the synchronization signal frequency; The control signal and the verification signal are superimposed by amplitude modulation or phase modulation to obtain a composite signal; Transmitting the integrated signal to each DAB module via a communication bus; The DAB module demodulates the integrated signal to separate the control signal and the check signal, and detects the integrity and correctness of the control signal according to the check signal.

2. The method according to claim 1, characterized in that The main controller includes a first DSP chip, a second DSP chip and an FPGA controller; The first DSP chip is used to sample the system voltage signal and current signal, and the second DSP chip is used to control the input current and output voltage of the primary and secondary H bridges in the DAB module, and to generate the modulation wave required by the primary and secondary H bridges and the phase shift value required by the DAB module.

3. The method according to claim 1, characterized in that The control signal includes a phase control signal, a power control signal and a current control signal; The phase control signal is used to adjust the phase shift angle of each DAB module, the power control signal is used to adjust the power reference signal of each DAB module, and the current control signal is used to adjust the current distribution of each DAB module.

4. The method according to claim 1, characterized in that: The DAB module demodulates the integrated signal to separate the control signal and the check signal, and detects the integrity and correctness of the control signal according to the check signal, and further includes: The DAB module feeds back the operating status information to the main controller through the status pointer, and the main controller adjusts the output of the control signal in real time according to the fed-back operating status information.

5. A PWM control signal transmission system, characterized in that: include: A main controller is used to generate a control signal and a corresponding verification signal according to the current and voltage sampling signals; and to superimpose the control signal and the verification signal through amplitude modulation or phase modulation to obtain a comprehensive signal, and transmit the comprehensive signal to each DAB module through a communication bus; Wherein, the generating of the control signal and the corresponding verification signal according to the current and voltage sampling signals also includes: The main controller sends a synchronization signal and a control signal once in each control cycle. At the initial moment of sending the synchronization signal, the control signal is fixed to a low level and a verification signal is generated synchronously; The switching signal frequency of the controller in the DAB module is set to an integer multiple of the synchronization signal frequency, and the control signal frequency is set to an integer multiple of the synchronization signal frequency; The DAB module is used to demodulate the integrated signal to separate the control signal and the check signal, and detect the integrity and correctness of the control signal according to the check signal.

6. The system according to claim 5, characterized in that The main controller includes a first DSP chip, a second DSP chip and an FPGA controller; The first DSP chip is used to sample the system voltage signal and current signal, and the second DSP chip is used to control the input current and output voltage of the primary and secondary H bridges in the DAB module, and to generate the modulation wave required by the primary and secondary H bridges and the phase shift value required by the DAB module.

7. The system according to claim 5, characterized in that The control signal includes a phase control signal, a power control signal and a current control signal; The phase control signal is used to adjust the phase shift angle of each DAB module, the power control signal is used to adjust the power reference signal of each DAB module, and the current control signal is used to adjust the current distribution of each DAB module.

8. The system according to claim 5, characterized in that The DAB module is also used to feed back operation status information to the main controller via a status pointer; Accordingly, the main controller adjusts the output of the control signal in real time according to the operation status information fed back by the DAB module.

Images