阅读说明：本技术 混合隔离型单相电力电子变压器 (Hybrid isolation type single-phase power electronic transformer ) 是由 高范强 李子欣 张宸宇 徐飞 赵聪 张航 李耀华 王平 于 2020-04-21 设计创作，主要内容包括：一种混合隔离型单相电力电子变压器,由电容隔离型变换器和高频变压器隔离型变换器组成。电容隔离型变换器由多个电容隔离型功率模块通过输入侧串联输出侧并联构成,可实现固定变比调压和电气隔离。高频变压器隔离型变换器采用多个高频隔离型功率模块通过输入侧串联输出侧并联构成,在实现电气隔离的同时亦可实现电压变比可配置。本发明可根据混合隔离型单相电力电子变压器所接入电网的电压等级,对两类隔离型变换器的数量及高频变压器原、副边线圈匝数比配置。与现有电容隔离型变换器拓扑相比,本发明可实现高低压侧电压等级变换的任意配置。本发明通过高频电容实现电力电子变压器高、低压侧电路的电气隔离,具有运行效率高、体积小等优点。(A mixed isolated single-phase power electronic transformer is composed of a capacitance isolated converter and a high-frequency transformer isolated converter. The capacitance isolation type converter is formed by connecting a plurality of capacitance isolation type power modules in parallel through an input side and an output side in series, and can realize fixed transformation ratio voltage regulation and electrical isolation. The high-frequency transformer isolated converter is formed by connecting a plurality of high-frequency isolated power modules in parallel through the input side and the output side, and can realize the electrical isolation and the configurable voltage transformation ratio. The invention can configure the number of two types of isolation type converters and the turn ratio of the primary side coil and the secondary side coil of the high-frequency transformer according to the voltage grade of a power grid connected with the hybrid isolation type single-phase power electronic transformer. Compared with the existing capacitance isolation type converter topology, the invention can realize arbitrary configuration of high-low voltage side voltage grade conversion. The invention realizes the electrical isolation of the high-voltage side circuit and the low-voltage side circuit of the power electronic transformer through the high-frequency capacitor, and has the advantages of high operation efficiency, small volume and the like.)

1. a hybrid isolation type single-phase power electronic transformer is characterized by comprising a capacitance isolation type converter, a high-frequency transformer isolation type converter and a filter inductor L f, wherein the capacitance isolation type converter is formed by cascade connection of R capacitance isolation power modules CM-1, CM-2, … … and CM-R, R is a positive integer, each capacitance isolation power module comprises four connecting terminals Z1, Z2, Z3 and Z4, a connecting terminal Z2 of a kth capacitance isolation power module CM-k in the capacitance isolation type converter is connected to a connecting terminal Z1 of a kth +1 capacitance isolation power module CM- (k +1), and k is more than or equal to 1 and less than or equal to R-1, a connecting terminal Z1 of a 1 st capacitance isolation power module CM-1 in the capacitance isolation type converter is connected to an M point, and a connecting terminal Z2 of an R capacitance isolation power module CM-R in the capacitance isolation type converter is connected to a G point;

the high-frequency isolation type converter is formed by cascade connection of S high-frequency isolation type power modules HM-1, HM-2, … … and HM-S, wherein S is a positive integer; each high-frequency isolation type power module comprises four connecting terminals of Y1, Y2, Y3 and Y4; a connecting terminal Y2 of a kth high-frequency isolation type power module SM-k in the high-frequency transformation isolation type converter is connected to a connecting terminal Y1 of a kth +1 high-frequency isolation type power module SM- (k +1), and k is more than or equal to 1 and less than or equal to S-1; a connecting terminal Y1 of a 1 st high-frequency isolated power module SM-1 in the high-frequency transformation isolated converter is connected to a point G; a connecting terminal Y2 of an S-th high-frequency isolated power module SM-S in the high-frequency voltage transformation isolated converter is connected to a point N;

one end of the filter inductor L f is connected to point M, and the other end of the filter inductor L f is connected to the connection terminal Z1 of the capacitive isolation power module CM-1.

2. The hybrid isolated single-phase power electronic transformer of claim 1, wherein: the number R of capacitance isolation power modules in the capacitance isolation type converter and the turn ratio T of primary and secondary side coils of a high-frequency transformer in the high-frequency isolation type converter_fAccording to the voltage U of a single-phase high-voltage alternating-current port_ACAnd a low voltage DC port voltage U_DCConfiguring;

the capacitance isolation type power module in the capacitance isolation type converter does not have the voltage grade conversion function; the minimum R of the number of the capacitance isolation type power modules which are in cascade connection in the capacitance isolation type converter is set to be 1, and the maximum R is set to be:

wherein Rmax represents the maximum number of the capacitance isolation type power modules [ n ], [ n ]]Denotes rounding down, d_RCRepresents the average modulation ratio, U, of the AC input side in the capacitive isolated power module_DCExpressing the rated voltage of the low-voltage DC port, U_ACThe effective value of the voltage of the single-phase high-voltage alternating-current port is represented;

the high-frequency isolation type power module in the high-frequency isolation converter has a voltage grade conversion function; the number S of high-frequency isolated power modules which are connected in cascade in the high-frequency voltage transformation isolated converter can be configured into any positive integer, and the turn ratio T of the primary side coil and the secondary side coil of the high-frequency transformer at the moment_fIs configured to:

wherein, the [ alpha ], [ beta ]]Denotes rounding down, d_RHThe average modulation ratio of the alternating current input side in the high-frequency isolated power module is shown, and R represents the number of the capacitance isolated power modules which are connected in cascade.

Technical Field

The invention relates to a power electronic transformer, in particular to a hybrid isolation type single-phase power electronic transformer.

Background

The power electronic transformer is based on a high-frequency power electronic conversion technology, can realize the functions of electrical isolation and voltage grade conversion from high-voltage alternating current to low-voltage alternating current or direct current, also has the functions of renewable energy access, energy bidirectional controllability, electric energy quality control and the like, and has wide application prospects in the fields of smart power grids, energy internet, rail transit locomotive traction and the like.

Most of the prior art power electronic transformers realize the electrical isolation of high-voltage and low-voltage side circuits through medium-high frequency transformers, and the transformation ratio of the power electronic transformers is designed by configuring the turn ratio of primary and secondary side coils of the medium-high frequency transformers. However, the technical schemes have the problems that the operation efficiency of the high-voltage high-capacity medium-high frequency transformer is difficult to improve, the comprehensive optimization design of the electric-magnetic-thermal multi-physical field is difficult, the topology of a system circuit is complex and the like, the improvement of the efficiency and the power density of the power electronic transformer is influenced, the manufacturing cost is high, and the large-scale popularization and application are difficult. In another mode, the high-frequency capacitor is used for realizing the electrical isolation of the high-voltage side circuit and the low-voltage side circuit, compared with an isolation scheme adopting a medium-high frequency transformer, the high-frequency capacitor has higher volume power density, and the volume of the power electronic transformer can be reduced. However, the technical solution using the high frequency capacitor has the problem that the voltage conversion ratio is fixed and not adjustable.

The invention patents CN201010287926 and CN20102053675 adopt high-frequency capacitors to realize electrical isolation. The invention patents CN201310016540, CN201410135384, CN201510129159, CN 201674288, CN201710079402, CN201711082371, CN201811171060 and the like all adopt medium-high frequency transformers to realize electrical isolation.

Disclosure of Invention

The invention aims to overcome the defects of complex circuit topology, low efficiency, large volume and the like of the existing power electronic transformer adopting a high-frequency transformer to realize electrical isolation, and the problem of fixed and non-adjustable voltage transformation ratio of the existing power electronic transformer adopting a high-frequency capacitor to realize electrical isolation, and provides a hybrid isolation type single-phase power electronic transformer.

The hybrid isolated single-phase power electronic transformer consists of a capacitance isolated converter, a high-frequency isolated converter and a filter inductor L f.

The capacitance isolation type converter is formed by connecting R capacitance isolation power modules CM-1, CM-2, … … and CM-R in a cascade mode, wherein R is a positive integer. Each capacitive isolation power module comprises four connecting terminals Z1, Z2, Z3 and Z4. A kth capacitance isolation power module CM-k connecting terminal Z2 in the capacitance isolation type converter is connected to a kth +1 capacitance isolation power module CM- (k +1) connecting terminal Z1, and k is more than or equal to 1 and less than or equal to R-1; the CM-1 connection terminal Z1 of the 1 st capacitive isolation power module in the capacitive isolation type converter is connected to the point M; the connection terminal Z2 of the R-th capacitively isolated power module CM-R in the capacitively isolated converter is connected to point G.

The high-frequency isolation type converter is formed by cascade connection of S high-frequency isolation type power modules HM-1, HM-2, … … and HM-S, and S is a positive integer. Each high-frequency isolation type power module comprises four connecting terminals of Y1, Y2, Y3 and Y4. A connecting terminal Y2 of a kth high-frequency isolation type power module SM-k in the high-frequency transformation isolation type converter is connected to a connecting terminal Y1 of a kth +1 high-frequency isolation type power module SM- (k +1), and k is more than or equal to 1 and less than or equal to S-1; a connecting terminal Y1 of a 1 st high-frequency isolated power module SM-1 of the high-frequency voltage transformation isolated converter is connected to a point G; and a connecting terminal Y2 of an S-th high-frequency isolated power module SM-S of the high-frequency transformation isolated converter is connected to the point N.

One end of the filter inductor L f is connected to point M, and the other end of the filter inductor L f is connected to the capacitively isolated power module CM-1 connection terminal Z1.

The number R of capacitance isolation power modules in the capacitance isolation type converter and the turn ratio T of primary and secondary side coils of a high-frequency transformer in the high-frequency isolation type converter_fAccording to the voltage U of a single-phase high-voltage alternating-current port_ACAnd a low voltage DC port voltage U_DCAnd (4) configuring.

The capacitance isolation type power module in the capacitance isolation type converter does not have the voltage grade conversion function. The minimum R number of the capacitance isolation type power modules which are in cascade connection in the capacitance isolation type converter can be set to be 1, and the maximum R number can be set to be:

wherein Rmax represents the maximum number of the capacitance isolation type power modules [ n ], [ n ]]Denotes rounding down, d_RCRepresents the average modulation ratio, U, of the AC input side in the capacitive isolated power module_DCExpressing the rated voltage of the low-voltage DC port, U_ACAnd the effective value of the voltage of the single-phase high-voltage alternating-current port is represented.

The high-frequency isolation type power module in the high-frequency isolation converter has a voltage grade conversion function. The number S of high-frequency isolated power modules which are connected in cascade in the high-frequency voltage transformation isolated converter can be configured into any positive integer, and the turn ratio T of the primary side coil and the secondary side coil of the high-frequency transformer at the moment_fShould be configured to:

wherein, the [ alpha ], [ beta ]]Denotes rounding down, d_RHThe average modulation ratio of the alternating current input side in the high-frequency isolated power module is shown, and R represents the number of the capacitance isolated power modules which are connected in cascade.

Drawings

FIG. 1 is a schematic diagram of a hybrid isolated single-phase power electronic transformer circuit of the present invention;

FIG. 2 is a schematic circuit diagram of a capacitively isolated power module within the capacitively isolated converter of the present invention;

fig. 3 is a schematic circuit diagram of a high-frequency isolated power module of the high-frequency isolated converter of the present invention.

Detailed Description

The invention is further described below with reference to the accompanying drawings and the detailed description.

As shown in FIG. 1, the hybrid isolation type single-phase power electronic transformer comprises a capacitance isolation type converter, a high-frequency isolation type converter and a filter inductor L f, wherein the capacitance isolation type converter is formed by cascading R capacitance isolation power modules CM-1, CM-2, … … and CM-R, R is a positive integer, each capacitance isolation power module comprises four connecting terminals Z1, Z2, Z3 and Z4, a connecting terminal Z2 of a kth capacitance isolation power module CM-k in the capacitance isolation type converter is connected to a connecting terminal Z1 of a kth +1 capacitance isolation power module CM- (k +1), k is larger than or equal to 1 and smaller than or equal to R-1, a connecting terminal Z1 of a 1 st capacitance isolation power module CM-1 in the capacitance isolation type converter is connected to an M point, and a connecting terminal Z2 of an R th capacitance isolation power module CM-R in the capacitance isolation type converter is connected to a G point.

The high-frequency isolation type converter is formed by cascade connection of S high-frequency isolation type power modules HM-1, HM-2, … … and HM-S, and S is a positive integer. Each high-frequency isolation type power module comprises four connecting terminals of Y1, Y2, Y3 and Y4. A kth high-frequency isolation type power module SM-k connecting terminal Y2 in the high-frequency transformation isolation type converter is connected to a kth +1 high-frequency isolation type power module SM- (k +1) connecting terminal Y1, and k is more than or equal to 1 and less than or equal to S-1; a connecting terminal Y1 of a 1 st high-frequency isolated power module SM-1 in the high-frequency transformation isolated converter is connected to a point G; and an S high-frequency isolated power module SM-S connecting terminal Y2 in the high-frequency transformation isolated converter is connected to the N point.

One end of the filter inductor L f is connected to point M, and the other end of the filter inductor L f is connected to the capacitively isolated power module CM-1 connection terminal Z1.

As shown in FIG. 2, in the hybrid isolated single-phase power electronic transformer of the present invention, R capacitor isolated power modules CM-1, CM-2, … …, CM-R in the capacitor isolated converter are all power frequency AC rectification units H_gDC capacitor C_hHigh frequency inverter unit H_iNon-polar high-voltage isolation capacitor C_rResonant inductor L_rHigh frequency rectifying unit H_rAn output capacitor C_oAnd (4) forming. Terminal x of power frequency AC rectification unit_g、y_gRespectively connected with a DC capacitor C_hTerminal p_h、n_hConnected, high frequency inverter unit H_iTerminal x of_i、y_iAnd also with the dc capacitor C_hTerminal p_h、n_hAnd (4) connecting. High frequency rectifying unit H_rTerminal x of_r、y_rAnd output capacitor C_oTerminal p_o、n_oAnd (4) connecting. Terminal p of nonpolar high-voltage isolation capacitor Cr_r、n_rAre respectively connected to a high-frequency inversion unit H_iTerminal a of_iTerminal p of resonant inductor L r_LTerminal n of resonant inductor L r_LTerminal a connected to high-frequency rectifying unit Hr_r. Terminal b of high-frequency inverter unit Hi_iAnd a terminal b of the high frequency rectifying unit Hr_rAre connected together.

As shown in FIG. 3, S high-frequency isolated power modules HM-1, HM-2, … … and HM-S in the high-frequency isolated converter in the hybrid isolated single-phase power electronic transformer are all power frequency AC rectification unit H_gDC capacitor C_hHigh frequency inverter unit H_iNon-polar capacitor C_rHigh frequency transformer T_hHigh frequency rectifying unit H_rAn output capacitor C_oAnd (4) forming. Terminal x of power frequency AC rectification unit_g、y_gRespectively connected with a DC capacitor C_hTerminal p_h、n_hConnected, high frequency inverter unit H_iTerminal x of_i、y_iAnd also with the dc capacitor C_hTerminal p_h、n_hAnd (4) connecting. High frequency rectifying unit H_rTerminal x of_r、y_rAnd output capacitor C_oTerminal p_o、n_oAnd (4) connecting. Terminal p of nonpolar capacitor Cr_rNr are respectively connected to a high-frequency inverter unit H_iTerminal a of_iHigh frequency transformer T_hTerminal x1, high frequency transformer T_hThe terminals x2, x3 and x4 are respectively connected to the high frequency inverter unit H_iTerminal b_iTerminal a of high frequency rectifying unit Hr_r、b_r。

The invention can be used for measuring the effective value U of the voltage of the single-phase high-voltage alternating-current port_ACRated voltage U of low-voltage direct current port_DCConfiguring the number R of capacitance isolation power modules in the capacitance isolation type converter and the turn ratio T of primary and secondary side coils of a high-frequency transformer in the high-frequency isolation type converter_f。

The capacitance isolation type power module in the capacitance isolation type converter does not have the voltage grade conversion function. Taking the kth capacitor isolation power module CM-k in the capacitor isolation type converter as an example, the direct current capacitor C of the kth capacitor isolation power module CM-k is_hRated operating voltage U_hAnd its output capacitor C_oRated dc voltage U_oAre equal. The minimum R number of the capacitance isolation type power modules which are in cascade connection in the capacitance isolation type converter can be set to be 1, and the maximum R number can be set to be:

wherein, the [ alpha ], [ beta ]]Denotes rounding down, d_RCThe average modulation ratio at the ac input side in the capacitively isolated power module is shown.

The high-frequency isolation type power module in the high-frequency isolation converter has a voltage grade conversion function. Taking the kth high-frequency isolation power module HM-k in the high-frequency isolation type converter as an example, the direct-current capacitor C thereof_hRated operating voltage U_hAnd its output capacitor C_oRated (2)DC voltage U_oThe ratio of the number of turns is equal to the turn ratio Tf of the primary side coil and the secondary side coil of the high-frequency transformer. The number S of high-frequency isolated power modules in cascade connection in the high-frequency voltage transformation isolated converter can be configured into any positive integer, and the turn ratio Tf of the primary side coil and the secondary side coil of the high-frequency transformer is configured as follows:

wherein, the [ alpha ], [ beta ]]Denotes rounding down, d_RHThe average modulation ratio of the alternating current input side in the high-frequency isolation type power module is shown.

One embodiment of the hybrid isolated single-phase power electronic transformer of the invention is as follows: single phase high voltage ac port voltage u_s8000sin (100 π t) V, effective value U_AC8.0 kV. The rated voltage of the low-voltage direct-current port is 1.0 kV. The modulation ratio of the power frequency alternating current rectification unit in the capacitance isolation type power module is set as d_RC0.85. According to the fact that the capacitance isolation type power module in the capacitance isolation type converter does not have the voltage grade conversion function, the capacitance isolation type power module R can be set to the maximum_maxR is not set to 10, that is, 10 capacitive isolation power modules are provided 13. The rated dc voltage at the output side of each module is 1.0 kV. The modulation ratio of the power frequency alternating current rectification unit in the high-frequency isolation type power module is set as d_RHThe number S of the high-frequency isolation type power modules is not configured to be 2 when being equal to 0.85, and the turn ratio T of the primary side coil and the secondary side coil of the high-frequency transformer is at the moment_fConfigurable as T_f1.654 ≈ 43: 26. the hybrid isolated single-phase power electronic transformer comprises 10 capacitance isolated converters and 2 high-frequency isolated converters, wherein the turn ratio of an original secondary side of the high-frequency isolated converters is 43: 26.