A quasi-single-stage three-phase pulse power supply and a control method thereof

Abstract

This invention discloses a quasi-single-stage three-phase pulse power supply and its control method. The quasi-single-stage three-phase pulse power supply includes a three-phase T-type three-level rectifier and a synchronous rectifier converter. By injecting a zero-sequence component into the three-phase modulation wave, the power transferred from the T-type three-level rectifier to the low-voltage port is adjusted. Part of the energy is directly transferred to the load by the T-type three-level rectifier, achieving maximum power single-stage transmission and improving energy transmission efficiency. Furthermore, the wide-range fluctuation of the capacitors at the high-voltage and low-voltage output terminals of the T-type three-level rectifier compensates for the instantaneous power difference between input and output, suppressing the impact of pulse power on the AC power grid. Simultaneously, the synchronous rectifier converter compensates for voltage fluctuations at the low-voltage output terminal capacitor, providing a stable voltage to the pulse load. This invention achieves input-output power decoupling, suppresses the impact of pulse loads on the AC power grid, and improves energy transmission efficiency by maximizing power single-stage transmission, making it suitable for applications with pulse loads.

Description

Technical Field

[0001] This invention relates to a quasi-single-stage three-phase pulse power supply and its control method, belonging to the field of power electronic converters, particularly the field of AC-DC power conversion technology. Background Technology

[0002] Pulsed power supplies have a wide range of applications, including materials processing, medical and health care, radar, and high-energy physics research. However, the periodicity, abrupt changes, and high peak-to-average power ratio of pulsed power pose challenges to the stable operation of power grids.

[0003] Traditional pulse power supplies employ passive power decoupling, using passive components such as supercapacitors as instantaneous power support. By increasing the capacitance, they maintain voltage stability, which increases the size and weight of the power supply and reduces power density.

[0004] Three-phase AC / DC power supply systems can be classified into single-stage and multi-stage types based on the number of power conversion stages. Single-stage architectures have relatively fewer power devices and lower converter costs. Due to the single-stage power conversion, efficiency is higher. However, sudden additions and removals of pulsed power loads cause a series of problems in three-phase uncontrolled rectified AC / DC power supply systems, including harmonic pollution, frequency fluctuations, and voltage flicker, affecting the long-term stability of the power supply system. Patent (Publication No.: CN108377102A) proposes a two-stage architecture consisting of a non-isolated PFC converter, a controlled current source, and an isolated DC / DC converter. The controlled current source, composed of a non-isolated bidirectional converter, acts as an energy storage unit. When there is no pulse, energy is stored in the bidirectional converter capacitor; when a pulse occurs, the bidirectional converter discharges to compensate for the energy. This structure controls the input current based on the power conservation principle, achieving decoupling of the pulse current and reducing the PFC bus capacitance. However, since all energy undergoes two stages of conversion, energy transfer efficiency is reduced. Furthermore, the bidirectional converter needs to be designed according to the pulse peak value. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides a quasi-single-stage three-phase pulse power supply and its control method. It utilizes the highest single-stage power transfer ratio to resolve the power surge of pulse power on the power supply system, decouples input and output power, maximizes energy transfer efficiency, provides a stable supply voltage for pulse loads, and significantly reduces the size and weight of the equipment.

[0006] The present invention is achieved through the following technical solution.

[0007] The quasi-single-stage three-phase pulse power supply of the present invention includes a three-phase T-type three-level rectifier and a synchronous rectifier converter. The high-voltage output terminal of the three-phase T-type three-level rectifier is v. H Connected to the input terminal of the synchronous rectifier converter, the low-voltage output terminal V L With the output terminal v of the synchronous rectifier converterbuck It is connected in series and then connected to the load.

[0008] The three-phase T-type three-level rectifier includes a low-voltage port filter capacitor (C). L ), High-voltage port filter capacitor (C) H ), 3 bridge pre-filter capacitors (C a C b C c ), 3 bridge pre-filter inductors (L a L b L c ), 12 switching transistors including the S transistor of the same bridge arm of the T-type three-level rectifier. Hx S Zx (x = a, b, c) and clamping switch S Lx1 S Lx2 (x = a, b, c); the low-voltage port is used to provide a single-stage power path;

[0009] The switching transistor S Ha The emitter and S Za The collector connection; the switch S Hb The emitter and S Zb The collector connection; the switch S Hc The emitter and S Zc The collector connection; the switch S Ha S Hb S Hc The collector is connected to the capacitor C at the high-voltage port. H The high-voltage end; the switching transistor S Za S Zb S Zc The emitter is connected to the low-voltage port filter capacitor C. L One end (reference ground); the switch S La1 collector and S La2 The collector connection; the switch S Lb1 collector and S Lb2 The collector connection; the switch S Lc1 collector and S Lc2 The collector connection; the switch S La1 The emitter and S Za The collector connection; the switch S Lb1 The emitter and S Zb The collector connection; the switch S Lc1 The emitter and S Zc The collector connection; the switch S La2 S Lb2 and S Lc2The emitter is connected to the low-voltage port filter capacitor C. L The high-voltage end; the switching transistor S Za S Zb and S Zc The emitter is connected to the low-voltage port filter capacitor C. L The other end (reference ground); the filter inductor L a One end is connected to phase A of the power grid, and the other end is connected to switch S. Ha The emitter; the filter inductor L b One end is connected to phase B of the power grid, and the other end is connected to the switch S. Hb The emitter; the filter inductor L c One end is connected to the C-phase power grid, and the other end is connected to the switch S. Hc The emitter; the filter capacitor C a One end is connected to phase A of the power grid, and the other end is connected to phase C. b C c Connected; the filter capacitor C b One end is connected to phase B of the power grid, and the other end is connected to phase C. a C c Connected; the filter capacitor C c One end is connected to the C-phase power grid, and the other end is connected to the C-phase power grid. a C b Connected;

[0010] The synchronous rectifier converter includes one output filter capacitor C. buck 1 output filter inductor L buck Two switching transistors, S1 and S2;

[0011] The emitter of the switching transistor S1 is connected to the collector of the switching transistor S2; the collector of the switching transistor S1 is connected to the high-voltage port filter capacitor C. H The high-voltage terminal is connected to the high-voltage terminal; the emitter of the switching transistor S2 is connected to the high-voltage port filter capacitor C. H The other end is connected; the output filter inductor L buck One end is connected to the emitter of the switching transistor S1, and the other end is connected to the output filter capacitor C. buck The output filter capacitor C buck One end is connected to the output filter inductor L buck The other end is connected to the emitter of the switching transistor S2;

[0012] The quasi-single-stage three-phase pulse power supply control section is divided into two parts: T-type three-level rectifier control and synchronous rectifier converter control. The T-type three-level rectifier control is divided into four parts: DC-side total voltage control loop (201), low-voltage side voltage control loop (202), grid-side current control loop (203), and CBPWM modulation (204) with zero-sequence component injection. The DC-side total voltage control loop adopts peak voltage control, which is compared with the reference value. After being output by the PI regulator, it is used together with the grid current feedforward value IFD as the d-axis of the current loop. d The reference is used for the low-voltage side voltage control loop, which adopts peak voltage control and compares it with the reference value to obtain the proportion of zero-sequence component after passing through a PI regulator. The grid-side current control loop obtains the initial three-phase modulation wave by inverse transformation of dq / abc based on the grid-side current d / q axis reference. The CBPWM modulation that injects zero-sequence component generates the final modulation wave after injecting zero-sequence component based on the initial three-phase modulation wave, and obtains the driving signals of each switch by intersecting with the triangular wave. The synchronous rectifier converter control adopts dual-loop control of voltage and current. The voltage loop controls the stable output voltage, and its output is used as the reference of the current loop. The load current is fed forward to improve the current tracking speed.

[0013] The key innovations and advancements of this quasi-single-stage three-phase pulse power supply compared to existing solutions are as follows:

[0014] 1. By utilizing the wide-range fluctuation of the energy storage capacitor, input and output power decoupling is achieved, ensuring that the AC input source only exhibits the average load power. This suppresses the power surges to the AC input source caused by sudden increases and decreases in pulse power, improving grid quality and enhancing the stability of the power supply system.

[0015] 2. Using the structure of this invention, by constructing a single-stage power path, part of the power passes through the low-voltage port V of the T-type three-level rectifier. L By directly supplying power to the load, the number of power conversion stages is reduced, thereby improving system efficiency.

[0016] 3. By injecting zero-sequence components, the power distribution of the high and low voltage ports of the T-type three-level rectifier is realized, so as to maximize the single-stage transmission of energy. Attached Figure Description

[0017] To more clearly illustrate the technical solutions of the present invention, the accompanying drawings used in the embodiments will be briefly described below. It should be understood that the following drawings only show some embodiments of the present invention and should not be considered as a limitation of the scope. For those skilled in the art, other related drawings can be obtained from these drawings without any creative effort.

[0018] Appendix Figure 1 A schematic diagram of a quasi-single-stage three-phase pulse power supply circuit;

[0019] Appendix Figure 2 The waveform diagram of the initial modulation wave of the three phases;

[0020] Appendix Figure 3 Waveform of the three-phase modulated wave after injecting the zero-sequence component at k=1;

[0021] Appendix Figure 4 Control block diagram of a T-type three-level rectifier for a quasi-single-stage three-phase pulse power supply;

[0022] Appendix Figure 5 Control block diagram of a quasi-single-stage three-phase pulse power supply synchronous rectifier converter;

[0023] Appendix Figure 6 The main working waveform diagrams are shown in the specific implementation example of a quasi-single-stage three-phase pulse power supply. Detailed Implementation

[0024] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, 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. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0025] The invention will now be further described with reference to the accompanying drawings.

[0026] As attached Figure 1 This is a circuit diagram of a quasi-single-stage three-phase pulse power supply. The quasi-single-stage three-phase pulse power supply includes a three-phase T-type three-level rectifier and a synchronous rectifier converter. The high-voltage output terminal of the three-phase T-type three-level rectifier is V... H Connected to the input terminal of the synchronous rectifier converter, the low-voltage output terminal V L With the output terminal v of the synchronous rectifier converter buck It is connected in series and then connected to the load.

[0027] The core of this quasi-single-stage three-phase pulse power supply is: 1. Providing power support through the periodic fluctuation of the energy storage capacitor voltage to offset the input-output power difference and achieve power decoupling; 2. Enabling as much power as possible to pass through the low-voltage port C. L It is transferred to the load to achieve maximum energy transfer in a single stage.

[0028] First, the core of power decoupling is to use energy storage components to compensate for the instantaneous input-output power difference, suppressing the power surge of sudden load increases and decreases on the AC input source, so that the AC input source only exhibits the average load power, thus improving the stability of the power supply system. Furthermore, it utilizes energy storage capacitor C... H and C L Wide voltage fluctuations allow for a reduction in capacitor value, resulting in a smaller power supply size and weight, and increased power density.

[0029] Second, achieve maximum power single-stage transmission as much as possible. To achieve maximum power single-stage transmission, the low-voltage port capacitor C should be made... L The power delivered to the load should be as much as possible, therefore, while ensuring that it does not exceed the load supply voltage V. o In this case, the low-voltage side capacitor voltage v should be increased as much as possible. L However, it is also necessary to consider whether the T-type three-level rectifier can achieve the required power distribution, so that more energy is allocated to the low-voltage port to meet the load requirements. This invention achieves power distribution by injecting a zero-sequence component into CBPWM, using a zero-sequence component of k*(-1-v). min )+(1-k)*(1-1-v max ), where v max With v min For the three-phase initial modulation wave u a1 u b1 u c1 The maximum and minimum values ​​are compared; k is obtained from the output of the low-voltage side voltage control loop. For example... Figure 2 This is the initial three-phase modulation wave, assuming the three-phase sinusoidal modulation wave is in phase with the three-phase current. For example... Figure 3 To inject a three-phase modulated wave with a zero-sequence component of k=1.

[0030] The specific control method of the quasi-single-stage three-phase pulse power supply in this invention is as follows:

[0031] 1) Detect the peak value V of the total DC side voltage of the T-type three-level rectifier. dcmax The DC side total voltage reference V dcmaxref and V dcmax After the subtractor calculates the difference, its output is adjusted by the proportional-integral regulator and used together with the grid current feedforward value as the d-axis of the current loop. d The benchmark.

[0032] 2) Detect the grid current i a i b i c The d / q axis current is obtained through abc / dq transformation, compared with a reference (the q axis reference is usually 0), and then adjusted by a proportional-integral controller to generate the dq axis component u. d u q The three-phase initial modulation wave u is obtained after dq / abc transformation.a1 u b1 u c1 .

[0033] 3) Detect the peak voltage VL at the low-voltage port of the T-type three-level rectifier. max The low-voltage port voltage reference VL maxref and VL max The difference is calculated by the subtractor, and its output is adjusted by the proportional-integral regulator to serve as the zero-sequence component parameter k.

[0034] 4) Detect the initial three-phase modulation wave u a1 u b1 u c1 The minimum value v of the modulated wave is obtained by comparison. min With the maximum value of the modulated wave v max The zero-sequence component parameter k described in step 3) is used to calculate the zero-sequence component k*(-1-v). min )+(1-k)*(1-1-v max The modulated wave is obtained by adding the three-phase initial modulated wave to the modulated wave. a u b u c Intersecting with the normalized upper and lower stacked triangular carrier waves to drive the switching transistor S Hx S Zx (x = a, b, c) and S Lx1 S Lx2 (x = a, b, c), the partial control block diagram of the T-type three-level rectifier is attached. Figure 4 As shown.

[0035] 5) Detect the load voltage V o Compared with reference value V oref The output of the subtractor, after being adjusted by a proportional-integral regulator, is added to the load current to serve as the reference value for the synchronous rectifier converter's current loop. The inductor current i of the synchronous rectifier converter is then detected. DC The proportional-integral regulator adjusts the drive signals for the synchronous rectifier converter switches to drive switches S1 and S2 by intersecting with a triangular wave. A partial control block diagram of the synchronous rectifier converter is attached. Figure 5 As shown.

[0036] The main working waveforms are attached. Figure 6 As shown in the figure. p load For pulse load power, i s For grid current, v H This refers to the high-voltage port voltage of a T-type three-level rectifier, v. L The low-voltage port voltage of the T-type three-level rectifier, v buck This is the output voltage of the synchronous rectifier converter. When the pulse peak occurs, the input power is less than the output power, C... H With CL Charging to compensate for the power difference, v H With v L The voltage drops to maintain the load voltage V. o stable v buck Rise. When the pulse trough occurs, the input power is greater than the output power, C H With C L Charging, v H With v L Rise, v buck decline.

[0037] The above description is merely an explanation of the present invention and not a limitation thereof. It should be noted that for those skilled in the art, several substitutions and improvements can be made without departing from the principle of the present invention, and these substitutions and improvements should also be considered within the scope of protection of the present invention.

Claims

1. A control method for a quasi-single-stage three-phase pulse power supply, comprising a three-phase T-type three-level rectifier and a synchronous rectifier converter; the high-voltage output terminal of the three-phase T-type three-level rectifier is V H Connected to the input terminal of the synchronous rectifier converter, the low-voltage output terminal V L With the output terminal v of the synchronous rectifier converter buck It is connected in series with a load, characterized in that: The main power circuit of the three-phase T-type three-level rectifier includes a low-voltage port filter capacitor C. L High-voltage port filter capacitor C H 3 bridge pre-filter capacitors C a C b C c 3 bridge pre-filter inductors L a L b L c The 12 switching transistors include the S transistor in the same bridge arm of the T-type three-level rectifier. Hx S Zx x = a, b, c and clamping switch S Lx1 S Lx2 x = a, b, c; The switching transistor S Ha The emitter and S Za The collector connection; the switch S Hb The emitter and S Zb The collector connection; the switch S Hc The emitter and S Zc The collector connection; the switch S Ha S Hb S Hc The collector is connected to the capacitor C at the high-voltage port. H The high-voltage end; the switching transistor S Za S Zb S Zc The emitter is connected to the low-voltage port filter capacitor C. L One end of the switch S; La1 collector and S La2 The collector connection; the switch S Lb1 collector and S Lb2 The collector connection; the switch S Lc1 collector and S Lc2 The collector connection; the switch S La1 The emitter and S Za The collector connection; the switch S Lb1 The emitter and S Zb The collector connection; the switch S Lc1 The emitter and S Zc The collector connection; the switch S La2 S Lb2 and S Lc2 The emitter is connected to the low-voltage port filter capacitor C. L The high-voltage end; the filter inductor L a One end is connected to phase A of the power grid, and the other end is connected to switch S. Ha The emitter; the filter inductor L b One end is connected to phase B of the power grid, and the other end is connected to the switch S. Hb The emitter; the filter inductor L c One end is connected to the C-phase power grid, and the other end is connected to the switch S. Hc The emitter; the filter capacitor C a One end is connected to phase A of the power grid, and the other end is connected to phase C. b C c Connected; the filter capacitor C b One end is connected to phase B of the power grid, and the other end is connected to phase C. a C c Connected; the filter capacitor C c One end is connected to the C-phase power grid, and the other end is connected to the C-phase power grid. a C b Connected; The synchronous rectifier converter includes one output filter capacitor C. buck 1 output filter inductor L buck Two switching transistors, S1 and S2; The emitter of the switching transistor S1 is connected to the collector of the switching transistor S2; the collector of the switching transistor S1 is connected to the high-voltage port filter capacitor C. H The high-voltage terminal is connected to the high-voltage terminal; the emitter of the switching transistor S2 is connected to the high-voltage port filter capacitor C. H The other end is connected; the output filter inductor L buck One end is connected to the emitter of the switching transistor S1, and the other end is connected to the output filter capacitor C. buck The output filter capacitor C buck One end is connected to the output filter inductor L buck The other end is connected to the emitter of the switching transistor S2; The quasi-single-stage three-phase pulse power supply control section is divided into two parts: T-type three-level rectifier control and synchronous rectifier converter control. The T-type three-level rectifier control is divided into four parts: DC-side total voltage control loop (201), low-voltage side voltage control loop (202), grid-side current control loop (203), and CBPWM modulation with zero-sequence component injection (204). The DC-side total voltage control loop adopts peak voltage control, which is compared with the reference value and output by the PI regulator, together with the grid current feedforward value, serves as the reference for the d-axis id of the current loop. The low-voltage side voltage control loop adopts peak voltage control. The zero-sequence component ratio is obtained by comparing the reference value with the PI regulator. The grid-side current control loop obtains the initial three-phase modulation wave by inverse dq / abc transformation based on the grid-side current d / q axis reference. The CBPWM modulation injecting the zero-sequence component generates the final modulation wave by injecting the zero-sequence component into the initial three-phase modulation wave, which intersects with the triangular wave to obtain the driving signals for each switch. The synchronous rectifier converter control adopts a dual-loop control of voltage and current. The voltage loop controls the stable output voltage, and its output serves as the reference for the current loop. Load current feedforward is added to improve the current tracking speed. Through capacitor C L With capacitor C buck The capacitor C is connected in series to provide the power required by the pulsed load. H and C L Provides instantaneous energy support, compensates for the difference between input and output power, ensures that the AC source exhibits only constant power, and suppresses the influence of pulse power on the AC input source. Capacitor C buck C caused by compensating for pulse load L Voltage fluctuations: A T-type three-level rectifier constructs two DC output ports with unequal voltages, and through power distribution, it allows as much energy as possible to pass through the C-type rectifier. L The energy is transferred to the load to achieve maximum power single-stage transmission and improve energy transfer efficiency. The steps are as follows: 1) Detect the peak value V of the total DC side voltage of the T-type three-level rectifier. dcmax The DC side total voltage reference V dcmaxref and V dcmax After the subtractor calculates the difference, its output is adjusted by the proportional-integral regulator and used together with the grid current feedforward value IFD as the d-axis of the current loop. d The benchmark; 2) Detect the grid current i a i b i c The d / q axis current i is obtained through abc / dq transformation. d i q After comparison with the benchmark, the proportional-integral controller is used for adjustment to generate the dq-axis component u. d u q The three-phase initial modulation wave u is obtained after dq / abc transformation. a1 u b1 u c1 ; 3) Detect the peak voltage V at the low-voltage port of the T-type three-level rectifier. Lmax The low-voltage port voltage reference V Lmaxref and V Lmax After the difference is calculated by the subtractor, its output is adjusted by the proportional-integral regulator as the zero-sequence component parameter k. 4) Detect the initial three-phase modulation wave u a1 u b1 u c1 The minimum value v of the modulated wave is obtained by comparison. min With the maximum value of the modulated wave v max Multiply the zero-sequence component parameter k obtained in step 3) by it and add it to the three-phase initial modulation wave to correct the modulation wave and obtain u. a u b u c Intersecting with the normalized upper and lower stacked triangular carrier waves to drive the switching transistor S Hx S Zx With S Lx1 S Lx2 ; 5) Detect the load voltage V o Compared with reference value V oref After the subtractor performs the difference operation, its output is adjusted by the proportional-integral regulator to match the load current i. p The sum is used as the reference value i for the current loop of the synchronous rectifier converter. DCref Detecting the inductor current i of the synchronous rectifier converter DC The proportional-integral regulator adjusts the synchronous rectifier converter's switching transistor drive signal, which intersects with the triangular wave to drive the switching transistors S1 and S2.

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