Control circuit and control method of high-power vibration power supply rectifier

Abstract

The invention provides a control circuit of a high-power vibration power supply rectifier and a control method thereof. The control circuit comprises a first PI controller, an SOGI and DSC cascade controller, a second PI controller and a PWM controller which are connected in sequence. And the output end of the PWM controller is connected with the input end of the high-power vibration power supply rectifier. And the first controller is connected between the first PI controller and the SOGI and DSC cascade controller, and the first controller receives a stable sine reference signal from a power grid and an output reference signal of the first PI controller and sends the stable sine reference signal and the output reference signal to the SOGI and DSC cascade controller. The stability, the efficiency and the electric energy quality of the power supply system are remarkably improved, and the harmonic content of the system is greatly reduced. And more accurate and efficient power support is provided for a vibration test system, so that the requirements of modern vibration test on high standard and high reliability are met.

Description

Technical Field

[0001] The present invention relates to a power electronic system, and more particularly to a control circuit and a control method for a novel high-power vibration power rectifier. Background Art

[0002] With the rapid development of technology, vibration testing, as an important part of modern industry and scientific research, has been widely used in fields such as aerospace, automotive manufacturing, electronic equipment, and precision machinery. It plays a crucial role in verifying the reliability and durability of products. The potential hazards caused by vibration cannot be ignored. For example, in machining, vibration will accelerate the wear of the mechanical structure and lead to a decrease in accuracy; in transportation, vibration will reduce the safety and comfort of vehicle driving. As an important form of ground vibration environment simulation, sinusoidal vibration is mainly achieved by an electro-vibration table system, and the vibration table power supply is the core component of this system. With the rapid development of new energy and intelligent manufacturing and other fields, the application prospects of the vibration table power supply system in industries such as aerospace, automotive, electronic products, and precision manufacturing are broader, providing strong technical support for higher-standard product testing and quality assurance.

[0003] Harmonics are caused by various nonlinear loads and power electronic devices, which propagate through the power system's transmission and distribution networks, resulting in distorted voltage and current waveforms. Harmonics not only affect the power quality of the power grid but may also have an adverse impact on the stability of equipment and systems. For a vibration power supply, excessive harmonic content will cause a decrease in the efficiency of the electro-vibration table and a reduction in the service life of the equipment.

[0004] To address the problems of grid disturbances and harmonic content in the AC-DC conversion system of vibration power supplies, several effective strategies have been proposed in the academic and industrial communities. First, it has been proposed to use TOSSI (third-order sine signal integrator) to filter out harmonics. Its basic idea is to perform integration processing on the input signal, so that high-order harmonic components (especially high-order harmonics other than the fundamental wave) are effectively removed, thereby retaining the fundamental wave component. However, its frequency tracking effect is poor and it cannot completely filter out low-order harmonics. Second, the proportional-integral multi-resonant control algorithm PIMR has been proposed. PIMR control eliminates the influence of the negative proportional term in repetitive control, improves the dynamic response of the system, and avoids the disadvantage of too many parameters in the multi-proportional-resonant controller. However, when the switching frequency is high, the problem of large storage space occupation has not been solved and the error convergence speed cannot be guaranteed in a wide frequency range, so further improvement is still needed. In contrast, the positive-sequence component separation method based on FFPS, which can quickly eliminate harmonics, has received extensive attention from scholars.

[0005] Compared with traditional harmonic elimination methods, the FFPS fundamental positive sequence component extractor can accurately extract the fundamental component in the case of severe harmonic and negative sequence pollution, is suitable for real-time control systems, has a low computational complexity, has strong anti-interference ability, and can effectively suppress noise. However, the performance of FFPS may be affected by non-linear loads or load imbalance, resulting in inaccurate extraction of the fundamental component and causing deviation in the control system.

[0006] When the grid signal is unbalanced, especially when there are negative sequence components, zero sequence components, frequency fluctuations, phase sequence errors or harmonic pollution, the accuracy of the fundamental component extraction by FFPS may be affected. Factors such as the interference of negative sequence and zero sequence components, the mixing of high-order harmonics, phase sequence errors and frequency drift will all cause FFPS to be unable to perfectly extract the fundamental component. Therefore, more complex signal processing methods need to be used to enhance the accuracy of fundamental component extraction in the case of strong imbalance or harmonic pollution. Summary of the Invention

[0007] To solve the above problems, the present invention proposes a novel control circuit and control method for a high-power vibration power supply rectifier.

[0008] Specifically, the present invention provides a control circuit for a high-power vibration power supply rectifier, including:

[0009] A first PI controller, a cascaded controller of SOGI and DSC, a second PI controller, and a PWM controller connected in sequence;

[0010] The output end of the PWM controller is connected to the input end of the high-power vibration power supply rectifier.

[0011] Further, it includes:

[0012] A first controller, which is connected between the first PI controller and the cascaded controller of SOGI and DSC. Among them, the first controller receives a stable sinusoidal reference signal from the grid and the output reference signal of the first PI controller, and sends them to the cascaded controller of SOGI and DSC.

[0013] Further, it includes:

[0014] A first adder and an inductor; the first adder is connected between the cascaded controller of SOGI and DSC and the second PI controller; the inductor is connected between the grid and the first adder; among them,

[0015] The first adder receives the outputs of the cascaded controller of SOGI and DSC and the inductor, and outputs a control signal to the second PI controller.

[0016] Further, it includes:

[0017] A second adder, a third adder, a third PI controller, and a fourth adder connected in sequence; wherein,

[0018] The fourth adder is also connected between the second PI controller and the PWM controller.

[0019] Further, the second adder calculates the difference between the first capacitor voltage and the second capacitor voltage, the third adder compares the magnitude relationship between the difference and zero, and then obtains the zero-sequence component of the controlled duty cycle through the third PI controller and outputs it to the fourth adder.

[0020] Further, it includes:

[0021] An analog load capacitor and a resistor; the analog load capacitor and the resistor are connected in parallel at the output end of the high-power vibration power supply rectifier.

[0022] Further, it includes:

[0023] An operational amplifier and a fifth adder; the input end of the operational amplifier is connected to the output end of the high-power vibration power supply rectifier, the output end of the operational amplifier is connected to one input end of the fifth adder; the other input end of the fifth adder is connected to a voltage reference signal, and the output end of the fifth adder is connected to the first PI controller.

[0024] Further, in the cascaded SOGI and DSC controller, the SOGI includes two adders, two integrators, two controllers, and a damping ratio calculator.

[0025] Further, in the cascaded SOGI and DSC controller, the DSC is used to eliminate the 5th harmonic and the 7th harmonic with the largest content in the remaining harmonic components of the system.

[0026] The present invention also provides a control method for the control circuit of the high-power vibration power supply rectifier according to the above, including:

[0027] Subtracting the actual voltage value from the voltage reference value to obtain a voltage deviation value, entering the first PI controller, and using the obtained output as the input signal of the current loop;

[0028] Sending the input signal into the SOGI to separate the positive and negative sequences and filter out the high-order harmonics in the input signal, then sending the coordinate components into the cascaded DSC to further filter out the remaining harmonic components, and finally obtaining the duty cycle of the insulated gate bipolar transistor IGBT in the high-power vibration power supply rectifier through the second PI controller and the PWM controller to control the on and off of the IGBT and realize the control of the output voltage and current.

[0029] The advantages of the present invention are as follows: The present invention significantly improves the stability, efficiency and power quality of the power system, and greatly reduces the harmonic content of the system. It provides more accurate and efficient power support for the vibration test system, thus meeting the requirements of modern vibration tests for high standards and high reliability. Brief Description of the Drawings

[0030] By reading the following detailed description of the preferred embodiments, various other advantages and benefits will become clear to those of ordinary skill in the art. The drawings are only for the purpose of showing the preferred embodiments and are not considered to be a limitation of the present invention. Moreover, throughout the drawings, the same reference numerals are used to represent the same components. In the drawings:

[0031] Figure 1 Shows the control structure block diagram of the high-power vibration power rectifier according to an embodiment of the present invention.

[0032] Figure 2 Shows the basic principle diagram of SOGI according to an embodiment of the present invention.

[0033] Figure 3 Shows the Bode plot of SOGI according to an embodiment of the present invention.

[0034] Figure 4 Shows the functional schematic diagram of SOGI according to an embodiment of the present invention.

[0035] Figure 5 Shows the schematic diagram of three-phase unbalanced voltage and current according to an embodiment of the present invention.

[0036] Figure 6 Shows the schematic diagram of the positive-sequence voltage component waveform according to an embodiment of the present invention.

[0037] Figure 7 Shows the schematic diagram of the DC-side voltage waveform according to an embodiment of the present invention.

[0038] Figure 8 Shows the schematic diagram of the output voltage THD content in the case of three-phase unbalanced voltage according to an embodiment of the present invention. Detailed Embodiments

[0039] The following will describe the exemplary embodiments of the present disclosure in more detail with reference to the drawings. Although the exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure can be implemented in various forms and should not be limited by the embodiments set forth herein. On the contrary, these embodiments are provided so that the present disclosure can be more thoroughly understood and the scope of the present disclosure can be completely conveyed to those skilled in the art.

[0040] Term Explanation:

[0041] SOGI (Second-Order Generalized Integrator): It is a filter based on a second-order generalized integrator that can extract amplitude and frequency information from a three-phase system or a sine wave. SOGI can effectively extract valid information from a sine signal containing noise and harmonics, has a fast-response dynamic ability, a simple structure, and a small computational load. However, in the case of strong disturbances, it will cause integration errors in the integrator and cannot completely eliminate low-order harmonics.

[0042] Cascaded DSC (Delayed Signal Cancellation): The DSC technology is a technique that uses a delayed signal to compare with the original signal to eliminate interference or noise. The DSC technology can filter out harmonics of specific orders, but in an unbalanced power system, DSC cannot quickly separate the positive- and negative-sequence fundamental components.

[0043] FFPS Fundamental Frequency Positive Sequence component extractor: The FFPS technology refers to decomposing the collected signal through an algorithm to remove high-frequency noise, harmonic components, as well as negative-sequence and zero-sequence components in the signal, and only retaining the fundamental and positive-sequence components. By using the fundamental frequency positive sequence component extractor, the total harmonic distortion of the current can be effectively reduced, the capacitor voltage fluctuation and the output voltage ripple can be decreased. Under the condition of grid voltage disturbance, the rectifier can operate stably.

[0044] The present invention proposes a rectifier control method for a positive- and negative-sequence component separator extractor based on SOGI and DSC, which utilizes the characteristics that SOGI can filter out high-order harmonics and DSC can filter out harmonics of specific orders to quickly and accurately separate the positive- and negative-sequence fundamental components of the power grid. This method can be used for the control of an unbalanced Pulse Width Modulation (PWM) rectifier. When an unbalanced fault occurs, it can keep the voltage on the DC side of the PWM rectifier stable.

[0045] The control structure block diagram of the high-power vibration power supply rectifier is as Figure 1 shown, including:

[0046] A first PI controller PI1, a cascaded controller of SOGI and DSC, a second PI controller PI2, and a PWM controller connected in sequence; the output end of the PWM controller is connected to the input end of an AC / DC rectifier (i.e., the high-power vibration power supply rectifier).

[0047] The first controller, which is connected between the first PI controller PI1 and the cascaded SOGI and DSC controllers. The first controller receives the stable sinusoidal reference signal Iabc_ref from the power grid and the output reference signal Idc_ref of the first PI controller PI1, and sends them to the cascaded SOGI and DSC controllers.

[0048] The first adder and inductor L2; the first adder is connected between the cascaded SOGI and DSC controllers and the second PI controller PI2; the inductor L2 is connected between the power grid (three-phase power grid) and the first adder; where the first adder receives the output Iabc of the cascaded SOGI and DSC controllers and the inductor L2, and outputs a control signal to the second PI controller PI2.

[0049] The second adder, third adder, third PI controller, and fourth adder connected in sequence; where the fourth adder is also connected between the second PI controller PI2 and the PWM controller.

[0050] The second adder calculates the difference between the first capacitor voltage Vc1 and the second capacitor voltage Vc2. The third adder compares the magnitude relationship between the difference and zero, and then obtains the zero-sequence component of the controlled duty cycle through the third PI controller and outputs it to the fourth adder.

[0051] The analog load capacitor C1 and resistor R1; the analog load capacitor C1 and resistor R1 are connected in parallel at the output end of the high-power vibration power supply rectifier.

[0052] The operational amplifier and the fifth adder; the input end of the operational amplifier is connected to the output end of the high-power vibration power supply rectifier, and the output end of the operational amplifier is connected to one input end of the fifth adder; the other input end of the fifth adder is connected to the voltage reference signal Vo_ref, and the output end of the fifth adder is connected to the first PI controller PI1.

[0053] Figure 1Among them, Vabc is the voltage extracted from the power grid, which is used to provide a stable sine signal. The box with an "×" is a controller. The Idc and the stable sine reference signal pass through the controller and are cascaded with SOGI and DSC to obtain the stable Iabc signal. The circle with an "×" is an adder. Subtracting Iabc from Iabc_ref can obtain the input of PI2. Here, PI1, PI2, and PI3 are all PI controllers, that is, proportional-integral controllers, and their function is to reduce the deviation. Vc1 and Vc2 are capacitor voltages. This part is a capacitor voltage balance control loop, and the main purpose is to balance the capacitor voltages, that is, Vc1 - Vc2 = 0. D0 is the zero-sequence component of the controlled duty cycle. C1 and R1 are the capacitance and resistance of the analog load, L2 is the inductor, and Vo is the output voltage.

[0054] Among them, the voltage deviation value obtained by subtracting the actual voltage value Vo from the voltage reference value Vo_ref enters the PI controller PI1, and the output obtained is the input of the current loop. This signal is sent to SOGI to separate the positive and negative sequences and filter out the high-order harmonics in the signal. Then, the coordinate components are sent to the cascaded DSC to further filter out the remaining harmonic components. Finally, through the current loop PI controller PI2 and the PWM controller, the duty cycle of the insulated-gate bipolar transistor (IGBT) is obtained to control the on and off of the IGBT, so as to realize the control of the output voltage and current.

[0055] The basic schematic diagram of SOGI is as Figure 2 shown. SOGI includes two adders, two integrators, two controllers, and a damping ratio calculator.

[0056] Among them, k is the damping ratio, k = 1.41; ω0 is the undamped natural frequency, ω0 = 50Hz; U in and u o represent the input signal and the output signal respectively. The phase of qu0 lags behind the phase of u o by 90°, while the amplitude is the same as that of u o . Among them, 1 / s is the integration link.

[0057] The transfer function of SOGI is, where s represents the integration coefficient:

[0058]

[0059] Figure 3 And Figure 4 are the Bode plot and the functional schematic diagram of SOGI. It can be seen from Figure 3 that SOGI can filter out high-order harmonics, Figure 4 and the "+" and "-" in

[0060] represent the positive sequence and the negative sequence respectively.Figure 3 It can be seen that although SOGI can filter out high-order harmonics, it cannot completely eliminate low-order harmonics. However, the content of low-order harmonics in the power grid is often greater than that of high-order harmonics in an unbalanced power system, such as the 5th and 7th harmonics. DSC can eliminate a specific number of harmonics, and by cascading two DSCs, the effect of eliminating the 5th and 7th harmonics can be achieved.

[0061] In the positive-sequence reference coordinate system, the positive-sequence component is a DC component, the negative-sequence component is twice the frequency of the AC component, and the nth harmonic component is the (n - 1)th harmonic; in the negative-sequence reference coordinate system, the negative-sequence component is a DC component, the positive-sequence component is twice the frequency of the AC component, and the nth harmonic component is the (n + 1)th harmonic. Since the harmonic components are all sinusoidal components, they can be eliminated by DSC.

[0062] In the positive-sequence and negative-sequence reference coordinate systems, the equation for eliminating the nth harmonic is (u represents voltage):

[0063]

[0064] In the formula, dq+ and dq- are the positive-sequence and negative-sequence reference coordinate systems respectively;

[0065] n refers to the nth harmonic;

[0066] t refers to any moment;

[0067] T refers to the fundamental period of the power grid;

[0068] In this invention, DSC is mainly used to eliminate the 5th and 7th harmonics, which are the most abundant in the residual harmonic components of the system. To eliminate the negative-sequence component and the 5th and 7th harmonics in the positive-sequence coordinate system, n takes 4 and 8; similarly, to eliminate the positive-sequence component and the 5th and 7th harmonics in the negative-sequence coordinate system, n takes 4 or 16.

[0069] Embodiment:

[0070] This invention establishes a simulation model to verify the correctness of the theory. It is found that the strategy proposed in this invention can output a voltage waveform with a certain quality under various load conditions, and can accurately separate the positive and negative sequence components even under voltage unbalance conditions, ensuring the stability of the unbalanced DC-side voltage.

[0071] Figure 5 For the voltage waveform and current waveform of the three-phase unbalanced voltage input in the simulation.

[0072] Figure 6 For the waveform of the positive-sequence voltage component extracted by the cascading method of SOGI and DSC. Figure 5 It is under the simulated voltage unbalance condition and is the input of the entire system.Figure 6 It shows that by adopting the extraction method of the present invention, the fundamental positive sequence component can be accurately extracted. Figure 7 and Figure 8 It can be illustrated that by adopting this solution, the output voltage is stable and controllable, and the harmonic content of the output is low, only 1.88%.

[0073] As mentioned above, the above is only a preferred specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention should be covered within the protection scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.

Claims

1. A control circuit for a high-power vibration power rectifier, characterized in that, It includes: A first PI controller, a cascaded SOGI and DSC controller, a second PI controller, and a PWM controller connected in sequence; The output end of the PWM controller is connected to the input end of the high-power vibration power supply rectifier.

2. The control circuit of a high-power vibration power supply rectifier according to claim 1, characterized in that It further includes: A first controller, which is connected between the first PI controller and the cascaded SOGI and DSC controller. Wherein, the first controller receives a stable sine reference signal from the power grid and the output reference signal of the first PI controller, and sends them to the cascaded SOGI and DSC controller.

3. The control circuit of a high-power vibration power supply rectifier according to claim 1 or 2, characterized in that, It further includes: A first adder and an inductor; the first adder is connected between the cascaded SOGI and DSC controller and the second PI controller; the inductor is connected between the power grid and the first adder; wherein, The first adder receives the outputs of the cascaded SOGI and DSC controller and the inductor, and outputs a control signal to the second PI controller.

4. The control circuit of a high-power vibration power supply rectifier according to claim 3, characterized in that It further includes: A second adder, a third adder, a third PI controller, and a fourth adder connected in sequence; wherein, The fourth adder is also connected between the second PI controller and the PWM controller.

5. The control circuit of a high-power vibration power supply rectifier according to claim 4, characterized in that The second adder calculates the difference between the first capacitor voltage and the second capacitor voltage, the third adder compares the magnitude relationship between the difference and zero, and then obtains the zero-sequence component of the controlled duty cycle through the third PI controller, and outputs it to the fourth adder.

6. The control circuit of a high-power vibration power rectifier according to claim 1 or 5, characterized in that It further includes: An analog load capacitor and a resistor; the analog load capacitor and resistor are connected in parallel at the output end of the high-power vibration power supply rectifier.

7. The control circuit of a high-power vibration power rectifier according to claim 6, characterized in that It further includes: An operational amplifier and a fifth adder; the input end of the operational amplifier is connected to the output end of the high-power vibration power supply rectifier, the output end of the operational amplifier is connected to one input end of the fifth adder; the other input end of the fifth adder is connected to a voltage reference signal, and the output end of the fifth adder is connected to the first PI controller.

8. The control circuit of a high-power vibration power supply rectifier according to claim 1 or 7, characterized in that In the cascaded SOGI and DSC controller, SOGI includes two adders, two integrators, two controllers, and a damping ratio calculator.

9. The control circuit of a high-power vibration power supply rectifier according to claim 1 or 7, characterized in that In the cascaded SOGI and DSC controller, DSC is used to eliminate the 5th harmonic and 7th harmonic with the largest content in the remaining harmonic components of the system.

10. A control method for a control circuit of a high-power vibration power rectifier according to any one of claims 1-9, characterized in that, It includes: The voltage reference value minus the actual voltage value to obtain a voltage deviation value, which enters the first PI controller, and the obtained output is used as the input signal of the current loop; The input signal is sent into the SOGI to separate the positive and negative sequences and filter out the high-order harmonics in the input signal. Then, the coordinate components are sent into the cascaded DSC to further filter out the remaining harmonic components. Finally, the duty cycle of the insulated gate bipolar transistor IGBT in the high-power vibration power rectifier is obtained through the second PI controller and the PWM controller to control the on / off of the IGBT and achieve the control of the output voltage and current.

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