阅读说明：本技术 单相交直流电力电子变压器 (Single-phase AC/DC power electronic transformer ) 是由 李子欣 胡钰杰 赵聪 高范强 徐飞 王平 李耀华 于 2019-09-09 设计创作，主要内容包括：一种单相交直流电力电子变压器,由半导体开关器件T<Sub>x1</Sub>-T<Sub>x4</Sub>、二极管D<Sub>x1</Sub>-D<Sub>x4</Sub>、半导体开关器件T<Sub>y1</Sub>、T<Sub>y2</Sub>、二极管D<Sub>y1</Sub>、D<Sub>y2</Sub>、高频隔离型双向DC/DC变换器、滤波电感L<Sub>f</Sub>和直流电容C<Sub>dc</Sub>组成。所述半导体开关器件T<Sub>x1</Sub>-T<Sub>x4</Sub>的开关状态由所述单相交直流电力电子变压器交流端口Z1和Z2端子之间的电压u<Sub>s</Sub>决定。所述的高频隔离型双向DC/DC变换器有两个直流端口,第二直流端口的电压u<Sub>P2N2</Sub>的实时控制目标为：u<Sub>P2N2</Sub>＝K×u<Sub>P1N1</Sub>,其中,u<Sub>P1N1</Sub>为高频隔离型双向DC/DC变换器第一直流端口的电压,K为不随时间变化的固定常数。所述的单相交直流电力电子变压器直流端口电压u<Sub>dc</Sub>及高频隔离型双向DC/DC变换器的第二直流端口的电流i<Sub>sec</Sub>均通过反馈方式进行双闭环控制。(A single-phase AC/DC power electronic transformer is composed of semiconductor switch device T x1 ‑T x4 Diode D x1 ‑D x4 Semiconductor switching device T y1 、T y2 Diode D y1 、D y2 High-frequency isolation type bidirectional DC/DC converter and filter inductor L f And a DC capacitor C dc And (4) forming. The semiconductor switching device T x1 ‑T x4 By the voltage u between the terminals of the ac port Z1 and Z2 of the single-phase ac/dc power electronic transformer s And (6) determining. The high-frequency isolated bidirectional DC/DC converter is provided with two DC ports, and the voltage u of the second DC port P2N2 The real-time control targets of (1) are: u. of P2N2 ＝K×u P1N1 Wherein u is P1N1 Is a first high-frequency isolated bidirectional DC/DC converterThe voltage at the dc port, K, is a fixed constant that does not change over time. The direct-current port voltage u of the single-phase alternating-current and direct-current power electronic transformer dc And the current i of the second direct current port of the high-frequency isolation type bidirectional DC/DC converter sec The double closed-loop control is carried out in a feedback mode.)

1. A single-phase AC/DC power electronic transformer is characterized in that the single-phase AC/DC power electronic transformer is composed of a semiconductor switching device T_x1-T_x4Diode D_x1-D_x4Semiconductor switching device T_y1、T_y2Diode D_y1、D_y2High frequency isolated bidirectionalDC/DC converter, filter inductance L_fAnd a DC capacitor C_dcComposition is carried out; semiconductor switch device T_x1Collector electrode of (1) and (D)_x1Are connected together, a semiconductor switching device T_x1Emitter and D_x1Are connected together; semiconductor switch device T_x2Collector electrode of (1) and (D)_x2Are connected together, a semiconductor switching device T_x2Emitter and D_x2Are connected together; semiconductor switch device T_x3Collector electrode of (1) and (D)_x3Are connected together, a semiconductor switching device T_x3Emitter and D_x3Are connected together; semiconductor switch device T_x4Collector electrode of (1) and (D)_x4Are connected together, a semiconductor switching device T_x4Emitter and D_x4Are connected together; the high-frequency isolated bidirectional DC/DC converter is provided with two DC ports, and positive and negative terminals of a first DC port of the high-frequency isolated bidirectional DC/DC converter are P₁、N₁The positive and negative terminals of the second direct current port of the high-frequency isolated bidirectional DC/DC converter are P₂、N₂(ii) a Semiconductor switch device T_x1Emitter and semiconductor switching device T_x2Is connected to point Z1, semiconductor switching device T_x3Emitter and semiconductor switching device T_x4Is connected to point Z2; semiconductor switch device T_x1T of_x3Is connected to the P of the high-frequency isolated bidirectional DC/DC converter₁Terminal, semiconductor switching device T_x2T of_x4Is connected to N of a high-frequency isolated bidirectional DC/DC converter₁A terminal; semiconductor switch device T_y1Emitter and semiconductor switching device T_y2Is connected to the P of the high-frequency isolated bidirectional DC/DC converter₂Terminal, semiconductor switching device T_y1Is connected to a DC capacitor C_dcPositive electrode terminal P of_dcSemiconductor switching device T_y2Is connected to a DC capacitor C_dcNegative electrode terminal N of_dc(ii) a Filter inductance L_fIs connected to a high-frequency isolated bidirectional DCN of/DC converter₂Terminal, filter inductance L_fIs connected to the DC capacitor C at the other end_dcNegative electrode terminal N of_dc(ii) a Z1 and Z2 are used as two connecting terminals of an alternating current port of the single-phase alternating current and direct current power electronic transformer and are connected to a single-phase alternating current power supply or a single-phase alternating current power grid; DC capacitor C_dcPositive electrode terminal P of_dcAnd a negative electrode terminal N_dcThe positive and negative terminals are respectively used as the direct current port of the single-phase alternating current and direct current power electronic transformer.

2. The single-phase ac/dc power electronic transformer of claim 1, wherein: semiconductor switch device T_x1-T_x4By the voltage u between the terminals of the ac port Z1 and Z2 of the single-phase ac/dc power electronic transformer_sDetermining the voltage u of the second DC port of the high-frequency isolated bidirectional DC/DC converter_z1z2>When 0, the semiconductor switch device T is turned on_x1And T_x4Turn off the semiconductor switching device T_x2And T_x3(ii) a When the voltage u of the second direct current port of the high-frequency isolation type bidirectional DC/DC converter_z1z2<When 0, the semiconductor switch device T is turned on_x2And T_x3Turn off the semiconductor switching device T_x1And T_x4(ii) a The voltage u of the second direct current port of the high-frequency isolated bidirectional DC/DC converter_P2N2The real-time control targets of (1) are: u. of_P2N2＝K×u_P1N1Wherein K is a constant which does not vary with time, u_P1N1The voltage of the first direct current port of the high-frequency isolation type bidirectional DC/DC converter is obtained.

3. The single-phase ac/dc power electronic transformer of claim 1, wherein: for the DC port P of the single-phase AC/DC power electronic transformer_dcAnd N_dcD.c. voltage u between_dcControlled by closed-loop feedback, the DC voltage u_dcThe reference value of the closed-loop feedback controller is the target voltage of the direct current port of the single-phase alternating current/direct current power electronic transformer; DC voltage u_dcClosed loop feedback ofThe controller output is Reg _ out _ u_dc(ii) a The second direct current port P of the high-frequency isolation type bidirectional DC/DC converter₂Current i of the terminal_secAlso controlled by closed-loop feedback, the second DC port P₂Current i of the terminal_secOf a closed loop feedback controller_{sec_ref}The reference value is determined by:

i_{sec_ref}＝Reg_out_u_dc×|u_z1z2|

wherein u is_z1z2The voltage between terminals Z1 and Z2 of the single-phase alternating current and direct current power electronic transformer is obtained;

second DC port P₂Current i of the terminal_secThe transfer function of the closed loop feedback controller of (1) is as follows:

Reg_i_sec(s)＝K_p+K_r2×s/[s²+(2ω₁)²]+K_r4×s/[s²+(4ω₁)²]

wherein, K_p、K_r2And K_r4The coefficients are constants and are respectively the coefficients of three parts of the closed-loop feedback controller, wherein Kp is the coefficient of a proportional part, Kr2 is the coefficient of a double-frequency resonance controller, and Kr4 is the coefficient of a quadruple-frequency resonance controller; omega₁For the voltage u between the terminals of the Z1 and Z2 of the single-phase AC/DC power electronic transformer_z1z2S is a laplace complex variable.

Technical Field

The present invention relates to power electronic transformers, and more particularly, to a high efficiency power electronic transformer having a single-phase ac port and a dc port and a control method thereof.

Background

Power electronic transformers generally implement complex functions of various electrical devices such as electrical isolation, voltage conversion, power transmission, and the like through power electronic converters and high-frequency transformers. The power electronic transformer has wide application prospect in the fields of smart power grids, renewable energy grid-connected power generation, alternating current and direct current hybrid power distribution networks, energy internet and the like.

The existing technical scheme of the power electronic transformer generally adopts a multi-link alternating current-direct current power electronic converter to realize the form conversion of electric energy, so that the system structure is complex, the number of required components is large, the efficiency is difficult to improve, the economical efficiency is poor, and the popularization and scale application of the power electronic transformer are seriously influenced. For example, chinese invention patents CN201310016540, CN201410135384, CN201510129159, CN201610274288, CN201710079402, CN201711082371, CN201811171060, etc. all have the above problems.

Disclosure of Invention

The invention aims to overcome the defects of multiple links, low efficiency, complex structure and the like of the conventional power electronic transformer, and provides a high-efficiency single-phase alternating current/direct current power electronic transformer circuit topology and a control method.

The invention relates to a semiconductor switching device T of a single-phase AC/DC power electronic transformer_x1-T_x4Diode D_x1-D_x4Semiconductor switching device T_y1、T_y2Diode D_y1、D_y2High-frequency isolation type bidirectional DC/DC transformerConverter and filter inductor L_fAnd a DC capacitor C_dcAnd (4) forming. Semiconductor switch device T_x1Collector electrode of (1) and (D)_x1Are connected together, a semiconductor switching device T_x1Emitter and D_x1Are connected together; semiconductor switch device T_x2Collector electrode of (1) and (D)_x2Are connected together, a semiconductor switching device T_x2Emitter and D_x2Are connected together; semiconductor switch device T_x3Collector electrode of (1) and (D)_x3Are connected together, a semiconductor switching device T_x3Emitter and D_x3Are connected together; semiconductor switch device T_x4Collector electrode of (1) and (D)_x4Are connected together, a semiconductor switching device T_x4Emitter and D_x4Are connected together. The high-frequency isolated bidirectional DC/DC converter is provided with two DC ports, and the positive and negative terminals of the first DC port of the high-frequency isolated bidirectional DC/DC converter are P₁、N₁The positive and negative terminals of the second DC port of the high-frequency isolated bidirectional DC/DC converter are respectively P₂、N₂Semiconductor switching device T_x1Emitter and semiconductor switching device T_x2Is connected to point Z1, semiconductor switching device T_x3Emitter and semiconductor switching device T_x4Is connected to point Z2; semiconductor switch device T_x1Collector electrode and T_x3Is connected to the P of the high-frequency isolated bidirectional DC/DC converter₁Terminal, semiconductor switching device T_x2Emitter and T_x4Is connected to N of a high-frequency isolated bidirectional DC/DC converter₁A terminal; semiconductor switch device T_y1Emitter and semiconductor switching device T_y2Is connected to the P of the high-frequency isolated bidirectional DC/DC converter₂Terminal, semiconductor switching device T_y1Is connected to a DC capacitor C_dcPositive electrode terminal P of_dcSemiconductor switching device T_y2Is connected to a DC capacitor C_dcNegative electrode terminal N of_dc(ii) a Filter inductance L_fIs connected at one end to highN of frequency isolation type bidirectional DC/DC converter₂Terminal, filter inductance L_fIs connected to the DC capacitor C at the other end_dcNegative electrode terminal N of_dc(ii) a Z1 and Z2 are used as two connecting terminals of an alternating current port of the single-phase alternating current and direct current power electronic transformer and are connected to a single-phase alternating current power supply or a single-phase alternating current power grid; DC capacitor C_dcPositive electrode terminal P of_dcAnd a negative electrode terminal N_dcThe positive and negative terminals are respectively used as the direct current port of the single-phase alternating current and direct current power electronic transformer.

The semiconductor switching device T_x1-T_x4By the voltage u between the terminals of the ac port Z1 and Z2 of the single-phase ac/dc power electronic transformer_sDetermine when u is_s>When 0, the semiconductor switch device T is turned on_x1And T_x4And turning off the semiconductor switching device T_x2And T_x3(ii) a When u is_s<When 0, the semiconductor switch device T is turned on_x2And T_x3And turning off the semiconductor switching device T_x1And T_x4(ii) a The voltage u of the second direct current port of the high-frequency isolated bidirectional DC/DC converter_P2N2The real-time control targets of (1) are: u. of_P2N2＝K×u_P1N1Wherein K is a constant that does not change with time; u. of_P1N1The voltage of the first direct current port of the high-frequency isolation type bidirectional DC/DC converter is obtained.

The direct current port P of the single-phase alternating current and direct current power electronic transformer_dcAnd N_dcD.c. voltage u between_dcControlled by closed-loop feedback, the DC voltage u_dcThe reference value of the closed-loop feedback controller is the target voltage of the direct current port of the single-phase alternating current/direct current power electronic transformer; DC voltage u_dcThe output of the closed loop feedback controller is Reg _ out _ u_dc(ii) a The second direct current port P of the high-frequency isolation type bidirectional DC/DC converter₂Current i of the terminal_secAlso controlled by closed-loop feedback, the second DC port P₂Current i of the terminal_secOf a closed loop feedback controller_{sec_ref}The reference value is determined by:

i_{sec_ref}＝Reg_out_u_dc×|u_z1z2|

wherein u is_z1z2The voltage between terminals Z1 and Z2 of the single-phase alternating current and direct current power electronic transformer is obtained;

second DC port P₂Current i of the terminal_secOf the closed loop feedback controller Reg _ i_sec(s) the following:

Reg_i_sec(s)＝K_p+K_r2×s/[s²+(2ω₁)²]+K_r4×s/[s²+(4ω₁)²]

wherein, K_p、K_r2And K_r4The coefficients of the three parts of the closed-loop feedback controller are respectively Kp is the coefficient of the proportional part, Kr2 is the coefficient of the double-frequency resonance controller, Kr4 is the coefficient of the quadruple-frequency resonance controller, K_p、K_r2And K_r4Are all constants; omega₁For the voltage u between the terminals of the Z1 and Z2 of the single-phase AC/DC power electronic transformer_z1z2S is a laplace complex variable.

Drawings

FIG. 1 is a schematic diagram of a single-phase AC/DC power electronic transformer circuit according to the present invention;

FIG. 2 is a schematic diagram of a specific circuit of a high-frequency isolated bidirectional DC/DC converter in the single-phase AC/DC power electronic transformer according to the present invention;

FIG. 3 is a simulation waveform of the AC port voltage and current of the single-phase AC/DC power electronic transformer according to the present invention;

fig. 4 is a simulation waveform of voltage and current at the dc port of the single-phase ac/dc power electronic transformer according to the present invention.

Detailed Description

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

As shown in figure 1, the single-phase AC/DC power electronic transformer of the invention is composed of a semiconductor switching device T_x1-T_x4Diode D_x1-D_x4Semiconductor switching device T_y1、T_y2Diode D_y1Diode D_y2High-frequency isolation type bidirectional DC/DC converter and filter inductor L_fAnd a DC capacitor C_dcAnd (4) forming. Semiconductor switch device T_x1Collector electrode of (1) and (D)_x1Are connected together, a semiconductor switching device T_x1Emitter and D_x1Are connected together; semiconductor switch device T_x2Collector electrode of (1) and (D)_x2Are connected together, a semiconductor switching device T_x2Emitter and D_x2Are connected together; semiconductor switch device T_x3Collector electrode of (1) and (D)_x3Are connected together, a semiconductor switching device T_x3Emitter and D_x3Are connected together; semiconductor switch device T_x4Collector electrode of (1) and (D)_x4Are connected together, a semiconductor switching device T_x4Emitter and D_x4Are connected together. The high-frequency isolated bidirectional DC/DC converter is provided with two DC ports, and positive and negative terminals of a first DC port of the high-frequency isolated bidirectional DC/DC converter are P₁、N₁The positive and negative terminals of the second direct current port of the high-frequency isolated bidirectional DC/DC converter are P₂、N₂Semiconductor switching device T_x1Emitter and semiconductor switching device T_x2Is connected to point Z1, semiconductor switching device T_x3Emitter and semiconductor switching device T_x4Is connected to point Z2; semiconductor switch device T_x1Collector electrode and T_x3Is connected to the P of the high-frequency isolated bidirectional DC/DC converter₁Terminal, semiconductor switching device T_x2Emitter and T_x4Is connected to N of a high-frequency isolated bidirectional DC/DC converter₁A terminal; semiconductor switch device T_y1Emitter and semiconductor switching device T_y2Is connected to the P of the high-frequency isolated bidirectional DC/DC converter₂Terminal, semiconductor switching device T_y1Is connected to a DC capacitor C_dcPositive electrode terminal P of_dcSemiconductor switching device T_y2Is connected to a DC capacitor C_dcNegative electrode terminal N of_dc(ii) a Filter inductance L_fIs connected to N of the high-frequency isolated bidirectional DC/DC converter₂Terminal, filter inductance L_fIs connected to the DC capacitor C at the other end_dcNegative electrode terminal N of_dc(ii) a Z1 and Z2 are used as two connecting terminals of an alternating current port of the single-phase alternating current and direct current power electronic transformer and are connected to a single-phase alternating current power supply or a single-phase alternating current power grid; DC capacitor C_dcPositive electrode terminal P of_dcAnd a negative electrode terminal N_dcThe positive and negative terminals are respectively used as the direct current port of the single-phase alternating current and direct current power electronic transformer.

The semiconductor switching device T_x1-T_x4By the voltage u between the terminals of the ac port Z1 and Z2 of the single-phase ac/dc power electronic transformer_sDetermine when u is_z1z2>When 0, the semiconductor switch device T is turned on_x1And T_x4And turning off the semiconductor switching device T_x2And T_x3(ii) a When u is_z1z2<When 0, the semiconductor switch device T is turned on_x2And T_x3And turning off the semiconductor switching device T_x1And T_x4(ii) a The voltage u of the second direct current port of the high-frequency isolated bidirectional DC/DC converter_P2N2The real-time control targets of (1) are: u. of_P2N2＝K×u_P1N1Wherein K is a fixed constant that does not change with time; u. of_P1N1The voltage of the first direct current port of the high-frequency isolation type bidirectional DC/DC converter is obtained.

The direct current port P of the single-phase alternating current and direct current power electronic transformer_dcAnd N_dcD.c. voltage u between_dcControl by closed-loop feedback_dcThe reference value of the closed-loop feedback controller is the target voltage of the direct current port of the single-phase alternating current/direct current power electronic transformer; u. of_dcThe output of the closed loop feedback controller is Reg _ out _ u_dc(ii) a The second direct current port P of the high-frequency isolation type bidirectional DC/DC converter₂Current i of the terminal_secAlso controlled by means of closed-loop feedback, the current i_secOf a closed loop feedback controller_{sec_ref}The reference value is determined by:

i_{sec_ref}＝Reg_out_u_dc×|u_z1z2|

wherein u is_z1z2The voltage between terminals Z1 and Z2 of the single-phase alternating current and direct current power electronic transformer is obtained; current i_secThe transfer function of the closed loop feedback controller of (1) is as follows:

Reg_i_sec(s)＝K_p+K_r2×s/[s²+(2ω₁)²]+K_r4×s/[s²+(4ω₁)²]

wherein, K_p、K_r2And K_r4The coefficients of the three parts of the closed-loop feedback controller are respectively Kp is the coefficient of the proportional part, Kr2 is the coefficient of the double-frequency resonance controller, Kr4 is the coefficient of the quadruple-frequency resonance controller, K_p、K_r2And K_r4Are all constants; are all constants, and omega 1 is the voltage u between the terminals of the alternating current port Z1 and the terminal Z2 of the single-phase alternating current and direct current power electronic transformer_z1z2S is a laplace complex variable.

Fig. 2 is a specific circuit schematic diagram of an embodiment of a high-frequency isolated bidirectional DC/DC converter in a single-phase ac/DC power electronic transformer according to the present invention. The high-frequency isolated bidirectional DC/DC converter adopts a series resonant double-active Bridge (DAB) type DC/DC converter and is composed of a direct-current capacitor C₁、C₂Semiconductor switch T₁-T₈Diode D₁-D₈High frequency transformer T_HFAnd a resonance capacitor C_rAnd (4) forming. Semiconductor switch T₂Collector and diode D₂Are connected together, a semiconductor switch T₂Emitter and diode D₂Are connected together; semiconductor switch T₃Collector and diode D₃Are connected together, a semiconductor switch T₃Emitter and diode D₃Are connected together; semiconductor switch T₄Collector and diode D₄Are connected together, a semiconductor switch T₄Emitter and diode D₄Are connected together; half ofConductor switch T₅Collector and diode D₅Are connected together, a semiconductor switch T₅Emitter and diode D₅Are connected together; semiconductor switch T₆Collector and diode D₆Are connected together, a semiconductor switch T₆Emitter and diode D₆Are connected together; semiconductor switch T₇Collector and diode D₇Are connected together, a semiconductor switch T₇Emitter and diode D₇Are connected together; semiconductor switch T₈Collector and diode D₈Are connected together, a semiconductor switch T₈Emitter and diode D₈Are connected together; semiconductor switch T₁、T₃Is connected to a capacitor C₁Positive electrode P of₁Semiconductor switch T₁、T₃Emitter and semiconductor switch T₂、T₄Is connected to the collector of the semiconductor switch T₂、T₄Is connected to a capacitor C₁Negative electrode N of₁. Semiconductor switch T₅、T₇Is connected to a capacitor C₂Positive electrode P of₂Semiconductor switch T₅、T₇Emitter and switch T of₆、T₈Is connected to the collector of the semiconductor switch T₆、T₈Is connected to a capacitor C₂Negative electrode N of₂. Resonant capacitor C_rOne end and an AC terminal a₁Connected with each other. Resonant capacitor C_rThe other end of (2) and a high-frequency transformer terminal x₁Connected, AC terminal b₁And a high-frequency transformer terminal y₁Are connected. AC terminal a₂And transformer terminal x₂Connected, AC terminal b₂And a transformer terminal y₂Are connected.

The 400V alternating current/750V direct current single-phase alternating current/direct current power electronic transformer built by the invention has the following simulation parameters:

ac port voltage: effective value 400V, frequency 50Hz

Dc port voltage: 750V

Rated voltage of primary and secondary sides of the high-frequency transformer: 565V:565V

High-frequency transformer conversion to high-voltage side leakage inductance L_r：6.33μH

Resonant capacitor C_r：10μF

Switching frequency: 19.2kHz

DAB dead time: 2 mus

DC capacitor C₁：50μF

DC capacitor C₂：50μF

DC port capacitor C_dc:30mF

Filter inductance L_f:1mH

Direct current port loading: 50kW resistance load

Fig. 3 and 4 are simulation verification results of the single-phase ac/dc power electronic transformer of the invention. In FIG. 3, u_sAC port voltage, i, for single-phase AC/DC power electronic transformers_priThe current is the alternating current port current of the single-phase alternating current and direct current power electronic transformer. According to the simulation result, the control method of the single-phase alternating current and direct current power electronic transformer has the advantages that the voltage and the current of the alternating current port are basically in the same phase, and the input current keeps good sine degree. In FIG. 4, u_dcVoltage at the DC port of a single-phase AC/DC power electronic transformer_dcThe power transformer is the direct current port current of a single-phase alternating current and direct current power electronic transformer amplified by five times. According to simulation results, the control method of the single-phase alternating current/direct current power electronic transformer has the advantages that the voltage of a direct current port is stabilized at 750V, and the output power is 50 kW. The simulation result verifies the feasibility and the correctness of the single-phase alternating current and direct current power electronic transformer.