CN-115912943-B - Control method of Vienna rectification topology based on SiC power device

Abstract

The invention discloses a control method of Vienna rectification topology based on a SiC power device, which comprises the steps of firstly establishing a three-phase VIENNA rectifier mathematical model; then carrying out the derivation of the neutral point voltage and current expression of the VIENNA rectifier, designing a current inner loop, designing a voltage outer loop, and finally carrying out neutral point potential balance control. The invention can realize the reduction of the volume of the VIENNA rectifying system, improve the power factor and reduce the system loss.

Inventors

• YANG LEI
• TIAN JIAQIANG
• ZHU DARUI
• TONG XIANGQIAN
• Jian Jiale
• CHEN XINZE
• Zhu Pengze
• ZHANG YUANQI
• LI XIAOJIE
• FENG BAOXIANG
• LIU XINGHUA
• WEN HAIBING

Assignees

• 西安理工大学

Dates

Publication Date

20260505

Application Date

20220831

Claims (3)

1. 1. The control method of the Vienna rectification topology based on the SiC power device is characterized by comprising the following steps: Step 1, establishing a three-phase VIENNA rectifier mathematical model; The step1 is specifically implemented according to the following steps: Step1, a three-phase three-level VIENNA rectifying circuit equation is as follows: in the formula (1): 、 、 Is the inductor current; The voltage from the neutral point of the capacitor to the neutral point of the power grid; 、 、 is the three-phase input voltage of the rectifier; The voltages input to the neutral points of the capacitors are three phases respectively; step 2, deducing a neutral point voltage and current expression of the VIENNA rectifier; In the step2, the neutral point voltage and current expression of the VIENNA rectifier is deduced as follows: As a phase a switch In the on state, the input terminal of the a phase of the rectifier is clamped at the voltage O at the midpoint of the direct current In the off state, the output voltage of the a-phase of the rectifier is Or (b) The positive and negative of the voltage depend on the polarity of a phase current, a voltage signal is sampled through power factor correction and unitized to obtain a unit sinusoidal signal with the same phase as the input voltage, a specific numerical value of the current signal is taken as gain and is overlapped with the unit sinusoidal signal at the moment to obtain the current signal with the same polarity as the voltage, finally, each phase voltage is provided with 3 levels, and the midpoint potential voltage at the opposite direct current side of each phase input end is expressed as follows: (2) In the formula (2) And Respectively direct current side filter capacitor And A voltage; when the neutral point potential of the direct current side is balanced, , The three-phase balance system is obtained by the formula (2) for outputting voltage at the direct current side: (3) Midpoint current Is the sum of the currents flowing through the three-phase power double-switch tube, and is expressed as follows: (4); step 3, designing a current inner ring; step4, designing a voltage outer ring; step 5, neutral point potential balance control; The step 5 specifically comprises the following steps: When the capacitor voltage at the DC side is unbalanced, let (11) Wherein the method comprises the steps of The voltage deviation of the capacitor at the upper and lower direct current sides is obtained; The neutral point potential compensation is introduced into the current control loop, and the neutral point bias compensation quantity is increased on the given current amplitude of the three phases, and the expression is as follows: (12) In the formula, Is the compensation coefficient of the neutral point if Greater than , Superimposing a DC component containing midpoint information in a given current reference The size of the particles becomes larger and, At the position of Less than Time deducting DC component containing midpoint information to make Becoming smaller; the current after the midpoint potential information is introduced is given as follows: (13) For a pair of A clipping process is applied.
2. 2. The control method of the vienna rectification topology based on the SiC power device according to claim 1, wherein the step 3 is specifically as follows: first voltage outer loop regulation, reference voltage And actual voltage The difference is made by comparison, error signals of the two are regulated by a PI controller and then output, and then the current inner loop is regulated, the collected network side voltage signal is sinusoidal by an SPLL controller unit and then is output with a voltage outer loop Multiplying, at this time, the output signal is used as the given value of the current loop to be in phase with the voltage of the network side to realize the power factor correction, meanwhile, the current loop compares the given value with the actual current of the input side to obtain an error signal, and meanwhile, in order to realize the neutral point potential balance control, the voltages at the two ends of the upper capacitor and the lower capacitor of the direct current output side are controlled Sampling difference, regulating amplitude limiting result and regulating current inner loop , The control of the VIENNA rectifier is realized through PWM driving after the comparison output of the current hysteresis controller; The minimum loop width calculation formula of rectifier hysteresis control is as follows: (5) wherein: The hysteresis loop width of the hysteresis loop link is T is the sampling period, L is the input side inductance; by the formula (5), the minimum loop width required by meeting the control requirement is calculated, and as the VIENNA rectifier uses a two-way switch, when the current direction is different, the current inner loop controller has different output logics, and the switching tube operation logic is as follows: (6) as a phase a, two-way switch One end is connected with the output end of the net side inductor, the other end is connected with the neutral point of the direct current output side filter capacitor, and the current is selected The direction from the power grid side to the load side is positive, and under the condition of normal operation of the circuit, the following analysis is carried out on the operating state of the VIENNA rectifier: (1) When (when) When in use, the two-way switch On, at this time, the ac side inductance In the energy storage state, input current The number of the cells to be processed is increased, Rising to the upper limit of hysteresis After that, the processing unit is configured to, Switch-off, ac side inductance Filter capacitor for leading a-phase upper bridge arm diode to direct current side Charging and discharging to load simultaneously, and alternating current side inductor Current on Decline to the lower limit of hysteresis After that, the processing unit is configured to, Restoring conduction; (2) When (when) When in use, the two-way switch On, at this time, the ac side inductance In the energy storage state, input current Decline to the lower limit of hysteresis After that, two-way switch Switch-off, ac side inductance Filter capacitor for leading a phase lower bridge arm diode to direct current side Charging and discharging to the load, the ac side inductor Current on Ascending until it is ready to Rising to the upper limit of hysteresis After that, the processing unit is configured to, And is turned back on.
3. 3. The control method of the vienna rectification topology based on the SiC power device according to claim 2, wherein the step 4 is specifically as follows: The voltage outer loop open loop transfer function is derived as follows: (7) In the formula, Is the inertia time constant And current inner loop small time constant 3 Times the sum of (2); Frequency bandwidth in voltage loop: (8) By carrying out parameter setting on a controller of a typical II type system, corresponding parameters are obtained: (9) taking the intermediate frequency width Substituting the parameters into the formula (9), calculating to obtain the parameters of the voltage outer loop PI controller as follows: (10) In the formula, Representing the small inertial time constant of the voltage outer loop sampling.

Description

Control method of Vienna rectification topology based on SiC power device Technical Field The invention belongs to the technical field of nonlinear control, and particularly relates to a control method of a Vienna rectification topology based on a SiC power device. Background The Vienna rectifier is rectifying equipment formed by adopting a three-phase three-level VIENNA rectifying topology, has the advantages of high output power density, less element stress, less current harmonic wave at the network side and higher power factor, and is widely applied to the fields of civil engineering, industry and the like. Compared with the traditional three-level rectifying circuit, the VIENNA circuit also has the problem of voltage fluctuation of an inherent midpoint, and in addition, in steady-state operation, the VIENNA rectifying device adopting the traditional Si power element is limited by the material characteristics of the traditional Si-based element: The Si-based IGBT has the advantages that the turn-off loss of the Si-based IGBT cannot be effectively reduced under the effect of trailing current when the Si-based IGBT is turned off, the working switching speed of the Si-based IGBT is limited, the internal on-resistance of the Si-based IGBT is increased along with the increase of junction temperature due to the positive temperature coefficient characteristic of the Si-based IGBT, so that the conduction loss of the Si-based IGBT is larger when the Si-based IGBT operates at higher junction temperature, and the Si-based IGBT cannot keep low on-resistance in a wide power range under the influence of the conduction modulation effect when the Si-based IGBT is turned on positively, particularly when the power level is lower. In summary, the problems of low switching speed and high power consumption of the Si-based IGBT limit the development of high frequency and the miniaturization of the heat sink, so that the VIENNA rectifying circuit using the Si tube is difficult to be made into a miniaturized application product with higher efficiency and higher frequency. The SiC power device has obvious advantages compared with the material characteristics of Si-based power devices. In order to solve the problem of inherent midpoint current fluctuation of the VIENNA rectifying circuit and the product upgrading bottleneck caused by special material characteristics of Si-based devices, topology research of the VIENNA rectifying circuit based on the SiC power devices becomes a development trend. Disclosure of Invention The invention aims to provide a control method of a Vienna rectification topology based on a SiC power device, which can realize the reduction of the volume of a VIenNA rectification system, improve the power factor and reduce the system loss. The technical scheme adopted by the invention is that the control method of the Vienna rectification topology based on the SiC power device is implemented according to the following steps: Step 1, establishing a three-phase VIENNA rectifier mathematical model; step 2, deducing a neutral point voltage and current expression of the VIENNA rectifier; step 3, designing a current inner ring; step4, designing a voltage outer ring; And 5, neutral point potential balance control. The present invention is also characterized in that, The step 1 is specifically implemented according to the following steps: Step1, a three-phase three-level VIENNA rectifying circuit equation is as follows: In the formula (1), ia, ib and ic are inductive currents, U ON is a voltage from a capacitive neutral point to a grid neutral point, ua, ub and Uc are three-phase input voltages of a rectifier, and U ao、Ubo、Uco is a voltage from three phases to the capacitive neutral point. In step 2, the voltage and current expression in the VIENNA rectifier is deduced as follows: The voltage of the output end of the phase a of the rectifier is +U c1 or-U c2, the positive and negative of the voltage depend on the polarity of the phase a current, a voltage signal is sampled and unitized through power factor correction to obtain a unit sine signal in phase with the input voltage, a specific numerical value of the current signal is taken as a gain to be overlapped with the unit sine signal at the moment, the current signal with the same polarity as the voltage is obtained, finally, each phase voltage is provided with 3 levels, and the relative DC side midpoint potential voltage of each phase input end is expressed as follows: in the formula (2), U c1 and U c2 are respectively voltages of a direct-current side filter capacitor C 1 and a direct-current side filter capacitor C 2; When the neutral point potential of the direct current side is balanced, U c1＝Uc2＝Udc/2,Udc is the output voltage of the direct current side, and the three-phase balance system is obtained by the formula (2): The midpoint current i O is the sum of the currents flowing through the three-phase power double-switch tube and is expressed as follows: iO＝S