Bidirectional DC-DC power supply active damping control system and method

Abstract

The invention relates to the technical field of active damping control, and discloses a bidirectional DC-DC power supply active damping control system and method, and the system comprises a front-end AC input rectification module, an LLC resonant circuit, and a Buck converter module: the front-end AC input rectification module is used for converting an AC input voltage into a DC voltage; the LLC resonance circuit is used for inverting the rectified direct current voltage into alternating current with a set frequency and transmitting the alternating current to a secondary side through a transformer; and the Buck converter module is used for rectifying an alternating current signal and adjusting the alternating current signal into a required direct current output voltage, and further comprises an LC filter and an active damping control module. By adopting the active damping control method, the resonance peak caused by the LC filter can be effectively suppressed without additionally adding a physical resistor, so that the fluctuation of the output voltage is limited. According to the control strategy, the problems of power loss and heating caused by a traditional passive damping method are avoided, and the energy efficiency of the system is remarkably improved.

Description

Technical Field

[0001] The present invention relates to the technical field of active damping control, and in particular to a bidirectional DC-DC power supply active damping control system and method. Background Art

[0002] With the rapid development of power electronics technology, bidirectional DC-DC power supplies are widely used in electric vehicles, new energy storage, industrial applications and other fields. The core function of bidirectional DC-DC power supplies is to realize the bidirectional flow of electric energy and ensure the stable operation of the system through efficient voltage regulation and energy conversion. Among them, Buck converters are often used for voltage regulation at the output end, which achieves stable DC output by controlling the duty cycle of the switch. However, in practical applications, the LC filter at the output end of the Buck converter will cause resonance, resulting in output voltage fluctuations, which will affect the stability and reliability of the system.

[0003] Traditional resonance suppression technology mostly uses passive damping methods, that is, physical resistance is connected in series with the inductor or capacitor of the LC filter to increase the damping effect. Although this method can suppress the resonance peak, it will increase the power loss of the system and cause unnecessary heating, thereby reducing the efficiency of the system. In addition, increasing the actual resistance will also increase the size and cost of the circuit. Therefore, the method that relies solely on passive damping has great limitations in applications with high-efficiency energy conversion and output voltage stability. Summary of the invention

[0004] In view of the deficiencies in the prior art, the present invention provides a bidirectional DC-DC power supply active damping control system and method, which solves the problems mentioned in the above background technology.

[0005] To achieve the above objectives, the present invention is implemented through the following technical solutions: a bidirectional DC-DC power supply active damping control system, including a front-end AC input rectifier module, an LLC resonant circuit and a Buck converter module: The front-end AC input rectifier module is used to convert the AC input voltage into a DC voltage; The LLC resonant circuit is used to invert the rectified DC voltage into AC power of a set frequency and transmit it to the secondary side through the transformer; The Buck converter module is used to rectify and adjust the AC signal to the required DC output voltage, and further includes an LC filter and an active damping control module. The LC filter is used to filter the output voltage, and the active damping control module is used to suppress the resonance phenomenon caused by the LC filter. The active damping control module realizes the damping effect based on the control strategy of the virtual resistor, and simulates the damping effect equivalent to the actual resistor by feeding back the inductor current and the capacitor voltage to suppress the resonance peak.

[0006] Preferably, the active damping control module includes a current feedback control module, a voltage feedback control module and a virtual resistance calculation module: The current feedback control module is used to collect the inductor current signal; The voltage feedback control module is used to collect capacitor voltage signals; The virtual resistance calculation module generates a virtual resistance for adjusting the resonance peak value of the output voltage by combining the feedback current signal with the voltage signal.

[0007] Preferably, the generation and adjustment process of the virtual resistance is as follows: set up is the output voltage, is the inductor current, is the capacitor voltage, is a virtual resistor, according to the inductor current and capacitor voltage The feedback signal of the virtual resistor The generated calculation is: ; In the control algorithm, the virtual resistor is applied in the feedback loop to achieve the output voltage Adjustment of resonance peak: ; in, is the inductance value, is the capacitance value, is the input voltage. This transfer function describes the With the introduction of The increase of is suppressed, thereby reducing the fluctuation of output voltage.

[0008] Preferably, the system further comprises a lead compensator for improving the system gain reduction problem introduced by active damping, and the lead compensator improves the dynamic response performance of the system by introducing a positive phase compensation signal.

[0009] Preferably, the transfer function of the lead compensator is expressed as: ; in is the gain of the compensator, is the time constant of the look-ahead network, is a coefficient less than 1.

[0010] Preferably, the Buck converter adopts a dual closed-loop control structure of a current inner loop and a voltage outer loop, the output of the voltage outer loop is the command value of the inductor current, the output of the current inner loop is the input voltage command value of the LC filter, and a duty cycle signal is generated by comparing the input voltage with the feedback voltage.

[0011] Preferably, the system is controlled based on a TMS320F2837xD real-time microcontroller, and the microcontroller has multiple high-speed interfaces for quickly collecting inductor current signals and capacitor voltage signals to improve system response speed.

[0012] Preferably, the duty cycle signal utilizes an error , and is generated by a proportional-integral controller: ; in, , is the command value of the input voltage, is the actual input voltage, is the input voltage error, is the duty cycle signal, is the proportional gain, is the integral gain.

[0013] A bidirectional DC-DC power supply active damping control method comprises the following steps: Collect the inductor current and capacitor voltage output by the Buck converter; The inductor current and the virtual resistance are calculated to generate a compensated duty cycle signal; The inductor current and input voltage are controlled through the voltage outer loop and the current inner loop; Based on the active damping strategy, the resonance caused by the LC filter is suppressed to reduce the output voltage fluctuation; The dynamic response performance of the system is improved by using the lead compensator.

[0014] The present invention provides a bidirectional DC-DC power supply active damping control system and method, which has the following beneficial effects: 1. The present invention adopts an active damping control method. The present invention can effectively suppress the resonance peak caused by the LC filter without adding additional physical resistance, thereby limiting the fluctuation of the output voltage. This control strategy avoids the power loss and heating problems caused by the traditional passive damping method, and significantly improves the energy efficiency of the system.

[0015] 2. The present invention optimizes the response speed of the system when the load changes rapidly by introducing the lead compensator into the control strategy, effectively reducing the amplitude of voltage drop and time lag. The advanced microprocessor control system further improves the system's ability to quickly adapt to load changes and ensures the stability and reliability of the output voltage. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a schematic diagram of the system structure of the present invention; Figure 2 It is a structural schematic diagram of the active damping control module of the present invention; Figure 3 The figure is a flow chart of the method of the present invention. DETAILED DESCRIPTION

[0017] The technical solution of the present invention will be described clearly and completely below in conjunction with the accompanying drawings of the present invention. Obviously, the described embodiments 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.

[0018] Example: Please refer to the attached Figure 1 -Attached Figure 3 The embodiment of the present invention provides a bidirectional DC-DC power supply active damping control system, including a front-end AC input rectifier module, an LLC resonant circuit and a Buck converter module: Front-end AC input rectifier module, used to convert AC input voltage into DC voltage; LLC resonant circuit, used to invert the rectified DC voltage into AC power of a set frequency and transmit it to the secondary side through a transformer; The Buck converter module is used to rectify and adjust the AC signal to the required DC output voltage, and further includes an LC filter and an active damping control module. The LC filter is used to filter the output voltage, and the active damping control module is used to suppress the resonance phenomenon caused by the LC filter. The active damping control module realizes the damping effect based on the control strategy of the virtual resistor, and simulates the damping effect equivalent to the actual resistor by feeding back the inductor current and the capacitor voltage to suppress the resonance spike.

[0019] The front-end AC input rectifier module converts the AC power into a DC voltage and connects its output to the LLC resonant circuit, which inverts the DC voltage into AC power of a set frequency and transmits it to the Buck converter module through a transformer. The Buck converter module receives the AC signal, rectifies it and adjusts it to the required DC output voltage. At the same time, the internal integrated LC filter smoothes the output voltage. The active damping control module suppresses the resonance phenomenon caused by the LC filter by simulating virtual resistance, thereby ensuring the stability and response speed of the system.

[0020] The active damping control module includes a current feedback control module, a voltage feedback control module and a virtual resistance calculation module: The current feedback control module is used to collect the inductor current signal. It is usually composed of current sensors. These sensors can accurately measure the current flowing through the inductor. Through analog or digital signal processing, the module converts the current signal into a feedback signal that can be used for control.

[0021] The voltage feedback control module is used to collect capacitor voltage signals and uses a voltage sensor to monitor the voltage across the capacitor. The module converts the collected voltage signal into a format suitable for control for subsequent processing.

[0022] The virtual resistance calculation module generates a virtual resistance for adjusting the resonant peak value of the output voltage by combining the feedback current signal with the voltage signal.

[0023] The generation and adjustment process of virtual resistance is as follows: set up is the output voltage, is the inductor current, is the capacitor voltage, is a virtual resistor, according to the inductor current and capacitor voltage The feedback signal of the virtual resistor The generated calculation is: , it can be seen from the formula that the virtual resistance The value of the capacitor voltage Divided by the inductor current This virtual resistor is used as an equivalent damping resistor in the control strategy to suppress the resonance peak of the LC filter; In the control algorithm, the virtual resistor is applied in the feedback loop to achieve the output voltage Adjustment of resonance peak: ; in, is the inductance value, is the capacitance value, is the input voltage. This transfer function describes the With the introduction of The increase of inductance and capacitance is suppressed, thereby reducing the fluctuation of output voltage. It can be seen from the formula that virtual resistance plays a key role in the feedback loop. With the increase of inductance and capacitance, the resonance peak is suppressed, thereby reducing the fluctuation of output voltage, improving the stability of the system, reducing overshoot and oscillation, and making the output voltage more stable and reliable.

[0024] The system also includes a lead compensator for improving the system gain reduction problem introduced by active damping. The lead compensator improves the dynamic response performance of the system by introducing a positive phase compensation signal.

[0025] The transfer function of the lead compensator is expressed as: ; in is the gain of the compensator, is the time constant of the look-ahead network, It is a coefficient less than 1. By introducing a positive phase within a certain frequency range, the phase margin of the system is increased, which can improve the stability of the system, reduce overshoot, and improve transient response.

[0026] The Buck converter adopts a dual closed-loop control structure of a current inner loop and a voltage outer loop. The output of the voltage outer loop is the command value of the inductor current, and the output of the current inner loop is the input voltage command value of the LC filter. The duty cycle signal is generated by comparing the input voltage with the feedback voltage.

[0027] Duty cycle signal utilization error , and is generated by a proportional-integral controller: ; in, , is the command value of the input voltage, is the actual input voltage, is the input voltage error, is the duty cycle signal, is the proportional gain, is the integral gain.

[0028] From the given formula, it can be concluded that the Buck converter adopts a dual closed-loop control structure, in which the voltage outer loop is responsible for setting the target value of the inductor current, and the current inner loop adjusts the input voltage of the LC filter according to this target value. The duty cycle signal is generated by comparing the error between the command value of the input voltage and the actual input voltage. The process involves a proportional-integral controller, which adjusts the duty cycle signal according to the size and duration of the error. The proportional gain determines the speed of response to the current error, while the integral gain helps to eliminate long-term steady-state errors. In this way, the Buck converter can accurately control the output voltage and ensure the stability and reliability of the power supply.

[0029] The system is controlled by a TMS320F2837xD real-time microcontroller, which has multiple high-speed interfaces for fast acquisition of inductor current signals and capacitor voltage signals to improve system response speed. This fast acquisition capability significantly improves the system response speed, allowing the control strategy to be adjusted in real time to adapt to transient load changes and input voltage fluctuations. The high-performance processing capability and multi-channel input design of the microcontroller ensure the accuracy and real-time nature of data acquisition, thereby improving the overall performance and reliability of the Buck converter.

[0030] A bidirectional DC-DC power supply active damping control method comprises the following steps: Collect the inductor current and capacitor voltage output by the Buck converter; The inductor current and the virtual resistance are calculated to generate a compensated duty cycle signal; The inductor current and input voltage are controlled through the voltage outer loop and the current inner loop; Based on the active damping strategy, the resonance caused by the LC filter is suppressed to reduce the output voltage fluctuation; The dynamic response performance of the system is improved by using the lead compensator.

[0031] This method first collects the inductor current and capacitor voltage signals output by the Buck converter. These signals are key indicators reflecting the transient response and stability of the power supply. Then, the inductor current is calculated with the preset virtual resistance value to generate a compensated duty cycle signal. In essence, the additional damping effect is simulated through algorithm adjustment, thereby improving the dynamic characteristics of the system without adding physical components.

[0032] Next, a dual closed-loop control structure combining an outer voltage loop and an inner current loop is adopted. The outer voltage loop is responsible for setting and adjusting the output voltage to the desired value, while the inner current loop quickly responds to changes in the inductor current to ensure that the current is adjusted strictly according to the instructions of the outer voltage loop. This fine control mechanism can effectively improve the stability and accuracy of the power supply.

[0033] In order to further suppress the resonance phenomenon caused by the LC filter, this method incorporates an active damping strategy. By actively introducing a signal that offsets the resonant frequency, the output voltage fluctuation caused by resonance is significantly reduced, thereby improving the stable output of the power supply over a wide load range.

[0034] Finally, the system integrates an advance compensator to predict and adjust the control signal in advance to cope with upcoming load changes or disturbances, greatly improving the system's dynamic response speed and anti-interference ability, ensuring that the power supply can maintain efficient and stable operation under various complex working conditions.

[0035] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A bidirectional DC-DC power supply active damping control system, characterized in that: Including front-end AC input rectifier module, LLC resonant circuit and Buck converter module: The front-end AC input rectifier module is used to convert the AC input voltage into a DC voltage; The LLC resonant circuit is used to invert the rectified DC voltage into AC power of a set frequency and transmit it to the secondary side through the transformer; The Buck converter module is used to rectify and adjust the AC signal to the required DC output voltage, and further includes an LC filter and an active damping control module. The LC filter is used to filter the output voltage, and the active damping control module is used to suppress the resonance phenomenon caused by the LC filter. The active damping control module realizes the damping effect based on the control strategy of the virtual resistor, and simulates the damping effect equivalent to the actual resistor by feeding back the inductor current and the capacitor voltage to suppress the resonance peak.

2. A bidirectional DC-DC power supply active damping control system according to claim 1, characterized in that: The active damping control module includes a current feedback control module, a voltage feedback control module and a virtual resistance calculation module: The current feedback control module is used to collect the inductor current signal; The voltage feedback control module is used to collect capacitor voltage signals; The virtual resistance calculation module generates a virtual resistance for adjusting the resonance peak value of the output voltage by combining the feedback current signal with the voltage signal.

3. A bidirectional DC-DC power supply active damping control system according to claim 1, characterized in that: The generation and adjustment process of the virtual resistance is as follows: set up is the output voltage, is the inductor current, is the capacitor voltage, is a virtual resistor, according to the inductor current and capacitor voltage The feedback signal of the virtual resistor The generated calculation is: ; In the control algorithm, the virtual resistor is applied in the feedback loop to achieve the output voltage Adjustment of resonance peak: ； in, is the inductance value, is the capacitance value, is the input voltage. This transfer function describes the With the introduction of The increase of is suppressed, thereby reducing the fluctuation of output voltage.

4. A bidirectional DC-DC power supply active damping control system according to claim 1, characterized in that: The system also includes a lead compensator for improving the system gain reduction problem introduced by active damping. The lead compensator improves the dynamic response performance of the system by introducing a positive phase compensation signal.

5. A bidirectional DC-DC power supply active damping control system according to claim 1, characterized in that: The transfer function of the lead compensator is expressed as: ； in is the gain of the compensator, is the time constant of the look-ahead network, is a coefficient less than 1.

6. A bidirectional DC-DC power supply active damping control system according to claim 1, characterized in that: The Buck converter adopts a dual closed-loop control structure of a current inner loop and a voltage outer loop. The output of the voltage outer loop is the command value of the inductor current, and the output of the current inner loop is the input voltage command value of the LC filter. The duty cycle signal is generated by comparing the input voltage with the feedback voltage.

7. A bidirectional DC-DC power supply active damping control system according to claim 1, characterized in that: The system is controlled based on a TMS320F2837xD real-time microcontroller, which has multiple high-speed interfaces for quickly collecting inductor current signals and capacitor voltage signals to improve the system response speed.

8. A bidirectional DC-DC power supply active damping control system and method according to claim 1, characterized in that: The duty cycle signal utilizes the error , and is generated by a proportional-integral controller: ； in, , is the command value of the input voltage, is the actual input voltage, is the input voltage error, is the duty cycle signal, is the proportional gain, is the integral gain.

9. A bidirectional DC-DC power supply active damping control method, according to a bidirectional DC-DC power supply active damping control system according to any one of claims 1 to 8, characterized in that: The following steps are involved: Collect the inductor current and capacitor voltage output by the Buck converter; The inductor current and the virtual resistance are calculated to generate a compensated duty cycle signal; The inductor current and input voltage are controlled through the voltage outer loop and the current inner loop; Based on the active damping strategy, the resonance caused by the LC filter is suppressed to reduce the output voltage fluctuation; The dynamic response performance of the system is improved by using the lead compensator.

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