阅读说明：本技术 一种电力变换器及其t型三电平三相整流电路 (Power converter and T-shaped three-level three-phase rectification circuit thereof ) 是由 赖熙庭 易龙强 牛兴卓 田华松 于 2020-04-30 设计创作，主要内容包括：本发明公开了一种T型三电平三相整流电路,包括：由A相T型电路,B相T型电路,C相T型电路,第一电容以及第二电容构成的T型三电平三相整流电路主体；电压检测电路,用于检测第一电容的电压和第二电容的电压；控制器,用于当根据第一电容的电压和第二电容的电压确定出T型三电平三相整流电路出现异常时,通过执行单元将T型三电平三相整流电路控制为非工作状态；设置在T型三电平三相整流电路中的执行单元。应用本申请的方案,可以有效地避免T型三电平三相整流电路中的横管故障导致的电容过压这样的二次故障情况。本申请还提供了一种电力变换器,具有相应技术效果。(The invention discloses a T-shaped three-level three-phase rectification circuit, which comprises: the T-type three-level three-phase rectification circuit main body consists of an A-phase T-type circuit, a B-phase T-type circuit, a C-phase T-type circuit, a first capacitor and a second capacitor; a voltage detection circuit for detecting a voltage of the first capacitor and a voltage of the second capacitor; the controller is used for controlling the T-shaped three-level three-phase rectification circuit to be in a non-working state through the execution unit when the T-shaped three-level three-phase rectification circuit is determined to be abnormal according to the voltage of the first capacitor and the voltage of the second capacitor; and the execution unit is arranged in the T-shaped three-level three-phase rectification circuit. By the scheme, the secondary fault condition of capacitor overvoltage caused by faults of the transverse tube in the T-shaped three-level three-phase rectification circuit can be effectively avoided. The application also provides a power converter with corresponding technical effects.)

1. A T-type three-level three-phase rectification circuit, comprising:

the T-type three-level three-phase rectification circuit main body consists of an A-phase T-type circuit, a B-phase T-type circuit, a C-phase T-type circuit, a first capacitor and a second capacitor; any one of the A-phase T-shaped circuit, the B-phase T-shaped circuit and the C-phase T-shaped circuit comprises a first inductor of the phase circuit, a first switching tube of the phase circuit, a second switching tube of the phase circuit, a third switching tube of the phase circuit and a fourth switching tube of the phase circuit; a first end of the first capacitor is used as a positive output end of the T-shaped three-level three-phase rectification circuit, a second end of the first capacitor is connected with a first end of the second capacitor and is used as a neutral point, and a second end of the second capacitor is used as a negative output end of the T-shaped three-level three-phase rectification circuit;

a voltage detection circuit for detecting a voltage of the first capacitor and a voltage of the second capacitor;

the controller is used for controlling the T-shaped three-level three-phase rectification circuit to be in a non-working state through the execution unit when the T-shaped three-level three-phase rectification circuit is determined to be abnormal according to the voltage of the first capacitor and the voltage of the second capacitor;

the execution unit is arranged in the T-shaped three-level three-phase rectification circuit.

2. The T-type three-level and three-phase rectifier circuit according to claim 1, wherein the controller is specifically configured to:

and when the voltage of the first capacitor and/or the voltage of the second capacitor are/is judged to be higher than a preset first voltage threshold value, determining that the T-shaped three-level three-phase rectification circuit is abnormal, and controlling the T-shaped three-level three-phase rectification circuit to be in a non-working state through an execution unit.

3. The T-type three-level and three-phase rectifier circuit according to claim 1, wherein the controller is specifically configured to:

and when the difference value between the voltage of the first capacitor and the voltage of the second capacitor is judged to exceed the preset voltage difference value range, determining that the T-shaped three-level three-phase rectification circuit is abnormal, and controlling the T-shaped three-level three-phase rectification circuit to be in a non-working state through an execution unit.

4. The T-type three-level three-phase rectification circuit according to claim 1, wherein the execution unit is a first bidirectional controllable switch unit with a first end connected with an M point and a second end connected with the neutral point, and the controller controls the T-type three-level three-phase rectification circuit to be in a non-working state by controlling the first end of the first bidirectional controllable switch unit and the second end of the first bidirectional controllable switch unit to be in a turn-off state;

the fourth switch tube of A looks T type circuit, the fourth switch tube of B looks T type circuit and the common connection point of the fourth switch tube of C looks T type circuit do M point, just the fourth switch tube of A looks T type circuit, the fourth switch tube of B looks T type circuit and the fourth switch tube of C looks T type circuit are violently managed.

5. The T-type three-level three-phase rectifier circuit according to claim 1, wherein said execution unit comprises:

the A-phase bidirectional controllable switch unit is connected with the A-phase alternating current input at a first end and connected with the first inductor of the A-phase T-type circuit at a second end;

the B-phase bidirectional controllable switch unit is connected with the B-phase alternating current input at a first end and connected with a first inductor of the B-phase T-shaped circuit at a second end;

the first end of the C-phase bidirectional controllable switch unit is connected with the C-phase alternating current input, and the second end of the C-phase bidirectional controllable switch unit is connected with the first inductor of the C-phase T-type circuit;

the controller controls the first end of the A-phase bidirectional controllable switch unit and the second end of the A-phase bidirectional controllable switch unit to be in an off state, controls the first end of the B-phase bidirectional controllable switch unit and the second end of the B-phase bidirectional controllable switch unit to be in an off state, and controls the first end of the C-phase bidirectional controllable switch unit and the second end of the C-phase bidirectional controllable switch unit to be in an off state, so that the T-type three-level three-phase rectification circuit is controlled to be in a non-working state.

6. The T-type three-level three-phase rectifier circuit according to any one of claims 1 to 5, further comprising:

a first voltage limiting circuit connected in parallel with the first capacitor;

a second voltage limiting circuit in parallel with the second capacitor.

7. The T-type three-level three-phase rectifier circuit according to claim 6, further comprising:

a first current detection circuit for detecting a current value of a current flowing through the first voltage limiting circuit;

a second current detection circuit for detecting a current value of a current flowing through the second voltage limiting circuit;

the controller is further configured to: and when the current value detected by the first current detection circuit and/or the current value detected by the second current detection circuit is higher than a preset first current threshold value, determining that the T-shaped three-level three-phase rectification circuit is abnormal, and controlling the T-shaped three-level three-phase rectification circuit to be in a non-working state through the execution unit.

8. The T-type three-level and three-phase rectifier circuit according to claim 6, wherein said first voltage limiting circuit is a first TVS diode or a first voltage dependent resistor; the second voltage limiting circuit is a second TVS diode or a second piezoresistor.

9. A T-type three-level three-phase rectification circuit according to any one of claims 1 to 5, wherein the controller is further configured to:

and after the T-shaped three-level three-phase rectification circuit is determined to be abnormal, controlling the A-phase T-shaped circuit, wherein each switch tube in the B-phase T-shaped circuit and each switch tube in the C-phase T-shaped circuit are in an off state.

10. A power converter comprising a T-type three-level three-phase rectifier circuit according to any one of claims 1 to 9.

Technical Field

The invention relates to the technical field of circuits, in particular to a power converter and a T-shaped three-level three-phase rectification circuit thereof.

Background

In the working process of the T-shaped three-level three-phase rectifying circuit, the situation that the capacitor at the output end is exploded due to overvoltage is found, and due to the conductivity and corrosivity of electrolyte, a printed board is scrapped after the electrolytic explosion generally. In addition, in practical application, the condition has no obvious relevance to the service life of the capacitor, namely, the capacitor is not damaged because the capacitor reaches the set service life.

In summary, how to effectively avoid the fault of the T-type three-level three-phase rectifier circuit caused by the overvoltage of the capacitor and even damage the printed board is a technical problem that needs to be solved by those skilled in the art.

Disclosure of Invention

The invention aims to provide a power converter and a T-shaped three-level three-phase rectifying circuit thereof, which are used for effectively avoiding the condition that the T-shaped three-level three-phase rectifying circuit is in failure and even damages a printed board caused by capacitor overvoltage.

In order to solve the technical problems, the invention provides the following technical scheme:

a T-type three-level three-phase rectification circuit comprises:

the T-type three-level three-phase rectification circuit main body consists of an A-phase T-type circuit, a B-phase T-type circuit, a C-phase T-type circuit, a first capacitor and a second capacitor; any one of the A-phase T-shaped circuit, the B-phase T-shaped circuit and the C-phase T-shaped circuit comprises a first inductor of the phase circuit, a first switching tube of the phase circuit, a second switching tube of the phase circuit, a third switching tube of the phase circuit and a fourth switching tube of the phase circuit; a first end of the first capacitor is used as a positive output end of the T-shaped three-level three-phase rectification circuit, a second end of the first capacitor is connected with a first end of the second capacitor and is used as a neutral point, and a second end of the second capacitor is used as a negative output end of the T-shaped three-level three-phase rectification circuit;

a voltage detection circuit for detecting a voltage of the first capacitor and a voltage of the second capacitor;

the controller is used for controlling the T-shaped three-level three-phase rectification circuit to be in a non-working state through the execution unit when the T-shaped three-level three-phase rectification circuit is determined to be abnormal according to the voltage of the first capacitor and the voltage of the second capacitor;

the execution unit is arranged in the T-shaped three-level three-phase rectification circuit.

Preferably, the controller is specifically configured to:

and when the voltage of the first capacitor and/or the voltage of the second capacitor are/is judged to be higher than a preset first voltage threshold value, determining that the T-shaped three-level three-phase rectification circuit is abnormal, and controlling the T-shaped three-level three-phase rectification circuit to be in a non-working state through an execution unit.

Preferably, the controller is specifically configured to:

and when the difference value between the voltage of the first capacitor and the voltage of the second capacitor is judged to exceed the preset voltage difference value range, determining that the T-shaped three-level three-phase rectification circuit is abnormal, and controlling the T-shaped three-level three-phase rectification circuit to be in a non-working state through an execution unit.

Preferably, the execution unit is a first bidirectional controllable switch unit having a first end connected to the M point and a second end connected to the neutral point, and the controller controls the T-type three-level three-phase rectifier circuit to be in a non-operating state by controlling a first end of the first bidirectional controllable switch unit and a second end of the first bidirectional controllable switch unit to be in an off state;

the fourth switch tube of A looks T type circuit, the fourth switch tube of B looks T type circuit and the common connection point of the fourth switch tube of C looks T type circuit do M point, just the fourth switch tube of A looks T type circuit, the fourth switch tube of B looks T type circuit and the fourth switch tube of C looks T type circuit are violently managed.

Preferably, the execution unit includes:

the A-phase bidirectional controllable switch unit is connected with the A-phase alternating current input at a first end and connected with the first inductor of the A-phase T-type circuit at a second end;

the B-phase bidirectional controllable switch unit is connected with the B-phase alternating current input at a first end and connected with a first inductor of the B-phase T-shaped circuit at a second end;

the first end of the C-phase bidirectional controllable switch unit is connected with the C-phase alternating current input, and the second end of the C-phase bidirectional controllable switch unit is connected with the first inductor of the C-phase T-type circuit;

the controller controls the first end of the A-phase bidirectional controllable switch unit and the second end of the A-phase bidirectional controllable switch unit to be in an off state, controls the first end of the B-phase bidirectional controllable switch unit and the second end of the B-phase bidirectional controllable switch unit to be in an off state, and controls the first end of the C-phase bidirectional controllable switch unit and the second end of the C-phase bidirectional controllable switch unit to be in an off state, so that the T-type three-level three-phase rectification circuit is controlled to be in a non-working state.

Preferably, the method further comprises the following steps:

a first voltage limiting circuit connected in parallel with the first capacitor;

a second voltage limiting circuit in parallel with the second capacitor.

Preferably, the method further comprises the following steps:

a first current detection circuit for detecting a current value of a current flowing through the first voltage limiting circuit;

a second current detection circuit for detecting a current value of a current flowing through the second voltage limiting circuit;

the controller is further configured to: and when the current value detected by the first current detection circuit and/or the current value detected by the second current detection circuit is higher than a preset first current threshold value, determining that the T-shaped three-level three-phase rectification circuit is abnormal, and controlling the T-shaped three-level three-phase rectification circuit to be in a non-working state through the execution unit.

Preferably, the first voltage limiting circuit is a first TVS diode or a first voltage dependent resistor; the second voltage limiting circuit is a second TVS diode or a second piezoresistor.

Preferably, the controller is further configured to:

and after the T-shaped three-level three-phase rectification circuit is determined to be abnormal, controlling the A-phase T-shaped circuit, wherein each switch tube in the B-phase T-shaped circuit and each switch tube in the C-phase T-shaped circuit are in an off state.

A power converter comprises the T-shaped three-level three-phase rectifying circuit.

By applying the technical scheme provided by the embodiment of the invention, the applicant considers the secondary fault condition of capacitor overvoltage caused by the fault of the transverse pipe in the T-shaped three-level three-phase rectification circuit, therefore, the voltage detection circuit is adopted to detect the voltage of the first capacitor and the voltage of the second capacitor, and the controller can determine whether the T-shaped three-level three-phase rectification circuit is abnormal or not according to the voltage of the first capacitor and the voltage of the second capacitor. If the T-shaped three-level three-phase rectification circuit is determined to be abnormal, the controller controls the T-shaped three-level three-phase rectification circuit to be in a non-working state through the execution unit. Therefore, when any one or more horizontal pipes of the T-shaped three-level three-phase rectifying circuit fail, the overvoltage protection mechanism can be timely found and triggered, namely the T-shaped three-level three-phase rectifying circuit is controlled to be in a non-working state, so that the situation that the printed board is exploded or even damaged due to overvoltage of the capacitor is avoided. In conclusion, the scheme of the application can effectively avoid the secondary fault condition of capacitor overvoltage caused by the fault of the transverse tube in the T-shaped three-level three-phase rectification circuit.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts.

FIG. 1 is a schematic diagram showing the current flow when a T-type three-level three-phase rectifier circuit is not provided with an N line and QA1 is short-circuited;

FIG. 2 is a schematic diagram of a T-type three-level three-phase rectifier circuit with an N-line and a QA1 short-circuited;

FIG. 3 is a schematic structural diagram of a T-shaped three-level three-phase rectification circuit according to the present invention;

fig. 4a is a schematic structural diagram of a first bidirectional controllable switch unit according to an embodiment of the present invention;

fig. 4b is a schematic structural diagram of a first bidirectional controllable switch unit according to an embodiment of the present invention;

fig. 4c is a schematic structural diagram of a first bidirectional controllable switch unit according to an embodiment of the present invention;

FIG. 5 is a schematic structural diagram of another T-shaped three-level three-phase rectification circuit according to the present invention;

fig. 6 is a schematic structural diagram of another T-type three-level three-phase rectifier circuit according to the present invention.

Detailed Description

The core of the invention is to provide a T-shaped three-level three-phase rectification circuit, which can effectively avoid the secondary fault condition of capacitor overvoltage caused by the fault of a transverse pipe in the T-shaped three-level three-phase rectification circuit.

In order that those skilled in the art will better understand the disclosure, the invention will be described in further detail with reference to the accompanying drawings and specific embodiments. It is to be understood that the described embodiments are merely exemplary of the invention, and not restrictive of the full scope of the invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

The applicant finds out through data analysis and experiments that in the working process of the T-shaped three-level three-phase rectification circuit, the situation that at least one transverse pipe fails due to overvoltage of normally working capacitors generally occurs, and therefore secondary faults of capacitor overvoltage are determined due to failure of one or more transverse pipes in the T-shaped three-level three-phase rectification circuit.

Referring to fig. 1, the T-type three-level three-phase rectifier circuit of fig. 1 has no N-line, and for example, if QA1 is short-circuited, the a-phase voltage sequentially goes through LA1, QA3, a body diode of QA4, C2, a body diode of QB2, and LB1 to the B-phase. Similarly, there is a path for voltage from phase a to phase C. By applying the live line voltage AB or AC directly to the capacitor C2 through the two paths, the voltage peak of the capacitor C2 will reach about 560V. In the charging module product, the voltage between Vbus + and Vbus-is generally about 800V, so that the capacitors with the voltage withstanding value of 450V are generally used for C1 and C2. It can thus be seen that after a short circuit failure of QA1, the voltage experienced at C2 will exceed its rated voltage causing C2 to electrolytically pop open. That is, the capacitor overvoltage is a secondary fault due to failure of one or more cross tubes.

Fig. 1 is an example of a T-type three-level three-phase rectifier circuit without N lines, which is still the case when the circuit is provided with N lines. Referring to fig. 2, the T-type three-level three-phase rectification circuit of fig. 2 is provided with N lines and still takes the example of a short circuit of QA 1. The a-phase input voltage will go through LA1, the body diodes of QA3, QA4 that are short circuited to N, causing an over-current condition that in turn causes a secondary fault condition of C2 over-voltage. Also, since the inductor LA1 is continuously subjected to dc voltage, LA1 loses the demagnetization circuit and causes saturation.

The scheme of this application then can avoid violently managing the condition appearance of the such secondary fault of electric capacity excessive pressure that the inefficacy triggered effectively.

Specifically, referring to fig. 3, fig. 3 is a schematic structural diagram of a T-type three-level three-phase rectifier circuit according to the present invention, where the T-type three-level three-phase rectifier circuit may include:

a T-type three-level three-phase rectifier circuit body consisting of an A-phase T-type circuit, a B-phase T-type circuit, a C-phase T-type circuit, a first capacitor C1 and a second capacitor C2; any one of the A-phase T-shaped circuit, the B-phase T-shaped circuit and the C-phase T-shaped circuit comprises a first inductor of the phase circuit, a first switching tube of the phase circuit, a second switching tube of the phase circuit, a third switching tube of the phase circuit and a fourth switching tube of the phase circuit; a first end of the first capacitor C1 is used as a positive output end of the T-type three-level three-phase rectification circuit, a second end of the first capacitor C1 is connected with a first end of the second capacitor C2 and is used as a neutral point, and a second end of the second capacitor C2 is used as a negative output end of the T-type three-level three-phase rectification circuit;

a voltage detection circuit 10 for detecting the voltage of the first capacitor C1 and the voltage of the second capacitor C2;

the controller 20 is used for controlling the T-shaped three-level three-phase rectifying circuit to be in a non-working state through the execution unit 30 when the T-shaped three-level three-phase rectifying circuit is determined to be abnormal according to the voltage of the first capacitor C1 and the voltage of the second capacitor C2;

and the execution unit 30 is arranged in the T-shaped three-level three-phase rectification circuit.

Specifically, the T-type three-level three-phase rectifier circuit main body described in the present application represents a structure of a conventional T-type three-level three-phase rectifier circuit, and may be a T-type three-level three-phase rectifier circuit with N lines, or a T-type three-level three-phase rectifier circuit without N lines. The T-type three-level three-phase rectification circuit comprises an a-phase T-type circuit, a B-phase T-type circuit, a C-phase T-type circuit, a first capacitor C1 and a second capacitor C2, and can be referred to in the figures. Any one of the A-phase T-shaped circuit, the B-phase T-shaped circuit and the C-phase T-shaped circuit comprises a first inductor of the phase circuit, a first switching tube of the phase circuit, a second switching tube of the phase circuit, a third switching tube of the phase circuit and a fourth switching tube of the phase circuit.

In the present embodiment, a first inductor of the a-phase T-type circuit is denoted by LA1, a first switch tube of the a-phase T-type circuit is denoted by QA1, a second switch tube of the a-phase T-type circuit is denoted by QA2, a third switch tube of the a-phase T-type circuit is denoted by QA3, and a fourth switch tube of the a-phase T-type circuit is denoted by QA 4. Accordingly, a first inductor of the B-phase T-type circuit is labeled as LB1, a first switch tube of the B-phase T-type circuit is labeled as QB1, a second switch tube of the B-phase T-type circuit is labeled as QB2, a third switch tube of the B-phase T-type circuit is labeled as QB3, and a fourth switch tube of the B-phase T-type circuit is labeled as QB 4. The first inductor of the C-phase T-type circuit is denoted as LC1, the first switch tube of the C-phase T-type circuit is denoted as QC1, the second switch tube of the C-phase T-type circuit is denoted as QC2, the third switch tube of the C-phase T-type circuit is denoted as QC3, and the fourth switch tube of the C-phase T-type circuit is denoted as QC 4.

A first end of the first inductor LA1 of the a-phase T-type circuit is used as an input end of the a-phase T-type circuit, and a second end of the first inductor LA1 of the a-phase T-type circuit is connected to a first end of the first switching tube QA1 of the a-phase T-type circuit, a first end of the second switching tube QA2 of the a-phase T-type circuit, and a first end of the third switching tube QA3 of the a-phase T-type circuit, respectively. The first end of the first inductor LB1 of the B-phase T-type circuit is used as the input end of the B-phase T-type circuit, and the second end of the first inductor LB1 of the B-phase T-type circuit is connected to the first end of the first switch tube QB1 of the B-phase T-type circuit, the first end of the second switch tube QB2 of the B-phase T-type circuit, and the first end of the third switch tube QB3 of the B-phase T-type circuit, respectively. The first end of the first inductor LC1 of the C-phase T-type circuit is used as the input end of the C-phase T-type circuit, and the second end of the first inductor LC1 of the C-phase T-type circuit is respectively connected with the first end of the first switch tube QC1 of the C-phase T-type circuit, the first end of the second switch tube QC2 of the C-phase T-type circuit and the first end of the third switch tube QC3 of the C-phase T-type circuit.

The second end of the third switch tube QA3 of the a-phase T-type circuit is connected with the first end of the fourth switch tube QA4 of the a-phase T-type circuit, the second end of the third switch tube QB3 of the B-phase T-type circuit is connected with the first end of the fourth switch tube QB4 of the B-phase T-type circuit, and the second end of the third switch tube QC3 of the C-phase T-type circuit is connected with the first end of the fourth switch tube QC4 of the C-phase T-type circuit. The second end of the fourth switching tube QA4 of the a-phase T-type circuit, the second end of the fourth switching tube QB4 of the B-phase T-type circuit and the second end of the fourth switching tube QC4 of the C-phase T-type circuit are connected to each other and to a common end of C1 and C2. In this application, a common terminal of the second terminal of the fourth switching tube QA4 of the a-phase T-type circuit, the second terminal of the fourth switching tube QB4 of the B-phase T-type circuit, and the second terminal of the fourth switching tube QC4 of the C-phase T-type circuit is denoted as point M. The common end of C1 and C2 is labeled as point O.

The second end of the first switch tube QA1 of the a-phase T-type circuit, the second end of the first switch tube QB1 of the B-phase T-type circuit and the second end of the first switch tube QC1 of the C-phase T-type circuit are connected to each other and to the first end of the first capacitor C1. The second end of the second switch tube QA2 of the a-phase T-type circuit, the second end of the second switch tube QB2 of the B-phase T-type circuit and the second end of the second switch tube QC2 of the C-phase T-type circuit are connected to each other and to the second end of the second capacitor C2.

The voltage detection circuit 10 of the present application can detect the voltage of the first capacitor C1 and the voltage of the second capacitor C2. It can be understood that the partial T-type three-level three-phase rectifier circuit may be originally provided with the voltage detection circuit 10 to detect the voltage of the first capacitor C1 and the voltage of the second capacitor C2, so that the application does not need to additionally configure the voltage detection circuit 10.

The controller 20 can determine whether the T-type three-level three-phase rectification circuit is abnormal or not according to the voltage of the first capacitor C1 and the voltage of the second capacitor C2, and if the T-type three-level three-phase rectification circuit is determined to be abnormal, an overvoltage protection mechanism is triggered, that is, the controller 20 controls the T-type three-level three-phase rectification circuit to be in a non-working state through the execution unit 30.

The execution unit 30 is arranged in the T-shaped three-level three-phase rectification circuit, the specific position selection and the specific circuit device composition of the execution unit 30 can be set and selected according to actual needs, and the T-shaped three-level three-phase rectification circuit can be controlled to be in a non-working state as required by the application. Because the T-shaped three-level three-phase rectification circuit is controlled to be in a non-working state, at the moment, although one or more transverse tubes in the circuit fail, the overvoltage of the capacitor cannot be further caused.

For example, in an embodiment of the present invention, the execution unit 30 is a first bidirectional controllable switch unit having a first end connected to the point M and a second end connected to the neutral point, and the controller 20 controls the T-type three-level three-phase rectification circuit to be in the non-operating state by controlling a first end of the first bidirectional controllable switch unit and a second end of the first bidirectional controllable switch unit to be in the off state;

the common connection point of the fourth switch tube QA4 of the a-phase T-type circuit, the fourth switch tube QB4 of the B-phase T-type circuit and the fourth switch tube QC4 of the C-phase T-type circuit is M point, and the fourth switch tube QA4 of the a-phase T-type circuit, the fourth switch tube QB4 of the B-phase T-type circuit and the fourth switch tube QC4 of the C-phase T-type circuit are all horizontal tubes.

Fig. 3 of the present application adopts an embodiment in which the common point of the cross tubes to which the a-phase T-type circuit, the B-phase T-type circuit, and the C-phase T-type circuit are connected is denoted as point M, that is, the common connection point of the fourth switching tube QA4 of the a-phase T-type circuit, the fourth switching tube QB4 of the B-phase T-type circuit, and the fourth switching tube QC4 of the C-phase T-type circuit in fig. 3 is denoted as point M, and the common end of the first capacitor C1 and the second capacitor C2 is denoted as point O, that is, the neutral point is denoted as point O.

It can be seen that, after the controller 20 determines that the T-type three-level three-phase rectifier circuit is abnormal, since the first bidirectional controllable switch unit is turned off, that is, the first end of the first bidirectional controllable switch unit and the second end of the first bidirectional controllable switch unit are controlled to be in an off state, the short-circuit current is blocked, and the condition that the voltage of the capacitor is overvoltage can be avoided.

When the execution unit 30 is selected as the first bidirectional controllable switch unit, the specific device form may also be set and adjusted as needed, for example, a relay may be selected as the first bidirectional controllable switch unit. For another example, any one of fig. 4a, 4b and 4c may be selected as the first bidirectional controllable switch unit, which does not affect the implementation of the present invention.

Of course, in other embodiments, the actuator 30 may be disposed in other manners besides disposing the actuator 30 between the common point and the neutral point of the cross tubes of the three phases.

For example, in the embodiment of fig. 5 of the present application, the execution unit 30 includes:

an a-phase bidirectional controllable switch unit 31 having a first end connected to an a-phase ac input and a second end connected to a first inductance LA1 of the a-phase T-type circuit;

a B-phase bidirectional controllable switch unit 32 having a first end connected to the B-phase ac input and a second end connected to a first inductor LB1 of the B-phase T-type circuit;

a C-phase bidirectional controllable switching unit 33 having a first end connected to the C-phase ac input and a second end connected to a first inductor LC1 of the C-phase T-type circuit;

the controller 20 controls the T-type three-level three-phase rectifier circuit to be in the non-operating state by controlling the first end of the a-phase bidirectional controllable switching unit 31 and the second end of the a-phase bidirectional controllable switching unit 31 to be in the off state, controlling the first end of the B-phase bidirectional controllable switching unit 32 and the second end of the B-phase bidirectional controllable switching unit 32 to be in the off state, and controlling the first end of the C-phase bidirectional controllable switching unit 33 and the second end of the C-phase bidirectional controllable switching unit 33 to be in the off state.

In this embodiment, the execution unit 30 is composed of an a-phase bidirectional controllable switch unit 31, a B-phase bidirectional controllable switch unit 32, and a C-phase bidirectional controllable switch unit 33, and when it is determined that the T-type three-level three-phase rectifier circuit is abnormal, the controller 20 turns off the a-phase bidirectional controllable switch unit 31, the B-phase bidirectional controllable switch unit 32, and the C-phase bidirectional controllable switch unit 33, so that the three-phase current input is turned off, the short-circuit current can be blocked, and the safety of the capacitor can be ensured, that is, the capacitor cannot be subjected to a secondary fault such as overvoltage.

In addition, the specific device configurations of the a-phase bidirectional controllable switch unit 31, the B-phase bidirectional controllable switch unit 32, and the C-phase bidirectional controllable switch unit 33 may also be selected according to actual needs, for example, for any one phase of controllable switch unit, a relay may be selected to implement, and any one of fig. 4a, fig. 4B, and fig. 4C may also be selected to implement.

The controller 20 of the present application may also have various rules for determining whether the T-type three-level three-phase rectifier circuit is abnormal, for example, in an embodiment of the present invention, the controller 20 is specifically configured to: when the voltage of the first capacitor C1 and/or the voltage of the second capacitor C2 are/is judged to be higher than a preset first voltage threshold value, the T-shaped three-level three-phase rectification circuit is determined to be abnormal, and the T-shaped three-level three-phase rectification circuit is controlled to be in a non-working state through the execution unit 30.

In this embodiment, when the controller 20 determines that the voltage of the first capacitor C1 and/or the voltage of the second capacitor C2 is higher than the preset first voltage threshold, it indicates that at least one capacitor is about to be over-voltage or even may be over-voltage, and if the capacitor is not timely processed, the capacitor may burst, and the electrolyte may corrode the printed board. Therefore, the controller 20 determines that an abnormality occurs in the T-type three-level three-phase rectifier circuit, and controls the T-type three-level three-phase rectifier circuit to be in a non-operating state through the execution unit 30.

For another example, in one embodiment of the present invention, the controller 20 is specifically configured to:

when the difference value between the voltage of the first capacitor C1 and the voltage of the second capacitor C2 is judged to be beyond the preset voltage difference value range, the T-shaped three-level three-phase rectification circuit is determined to be abnormal, and the T-shaped three-level three-phase rectification circuit is controlled to be in a non-working state through the execution unit 30.

In this embodiment, when the difference is determined to be beyond the preset voltage difference range, it is determined that an abnormality occurs in the T-type three-level three-phase rectification circuit, considering that the voltage of the first capacitor C1 and the voltage of the second capacitor C2 are not higher than the preset first voltage threshold, but the voltage difference between the first capacitor C1 and the second capacitor C2 is relatively high, when the cross tube failure may occur in some cases.

The specific values of the first voltage threshold and the voltage difference range can be set and adjusted according to actual needs. In addition, in practical applications, the controller 20 may determine whether the voltage of the first capacitor C1 and/or the voltage of the second capacitor C2 is higher than a preset first voltage threshold, and also determine whether a difference between the voltage of the first capacitor C1 and the voltage of the second capacitor C2 exceeds a preset voltage difference range, and if any of the two determinations is yes, it may be determined that the T-type three-level three-phase rectification circuit is abnormal, that is, it may be determined that at least one cross tube fails, and it is required to immediately control the T-type three-level three-phase rectification circuit to be in a non-operating state through the execution unit 30 to protect the capacitors of the circuit.

In an embodiment of the present invention, referring to fig. 6, the method further includes:

a first voltage limiting circuit 41 connected in parallel with the first capacitor C1;

a second voltage limiting circuit 42 connected in parallel with the second capacitor C2.

Note that, in fig. 6, the voltage detection circuit 10 is not shown for convenience of viewing the drawings. In this embodiment, after at least one transverse tube in at least one T-type three-level three-phase rectification circuit fails, if the protection scheme of the present application is not provided, a secondary fault condition that the capacitor is subjected to overvoltage explosion is considered, but even if the scheme of the present application controls the execution unit 30 through the controller 20, the T-type three-level three-phase rectification circuit is controlled to be in a non-working state, and the process requires a certain time, in the process, the short-circuit current still may directly cause the capacitor to be subjected to overvoltage explosion.

Therefore, in this embodiment, a first voltage limiting circuit 41 connected in parallel with the first capacitor C1 and a second voltage limiting circuit 42 connected in parallel with the second capacitor C2 are provided, so as to further protect the first capacitor C1 and the second capacitor C2.

Specifically, when at least one transverse tube in the T-shaped three-level three-phase rectification circuit fails, the voltage amplitude limiting circuit can act, so that the capacitor is protected. It can be understood that the operating voltage of the voltage limiting circuit generally needs to be higher than the voltage of the capacitor to be protected in the normal operation state and lower than the withstand voltage of the capacitor.

The specific device configuration of the voltage limiting circuit may also be set and adjusted as required, for example, in a specific embodiment of the present invention, the first voltage limiting circuit 41 may be selected as a first TVS diode or a first voltage dependent resistor which is commonly used; the second voltage limiting circuit 42 may also be selected as a second TVS diode or a second voltage dependent resistor.

Further, in an embodiment of the present invention, the method may further include:

a first current detection circuit 51 for detecting a current value of the current flowing through the first voltage limiter circuit 41;

a second current detection circuit 52 for detecting a current value of the current flowing through the second voltage limiter circuit 42;

the controller 20 is also configured to: when the current value detected by the first current detection circuit 51 and/or the current value detected by the second current detection circuit 52 is judged to be higher than the preset first current threshold value, it is determined that the T-type three-level three-phase rectification circuit is abnormal, and the T-type three-level three-phase rectification circuit is controlled to be in a non-working state through the execution unit 30.

In this embodiment, it is considered that the first voltage limiter circuit 41 and the second voltage limiter circuit 42 are provided, and when the first voltage limiter circuit 41 operates, the current in the first voltage limiter circuit 41 becomes excessively high, and the second voltage limiter circuit 42 is similarly configured. When the controller 20 determines that the current value detected by the first current detection circuit 51 and/or the current value detected by the second current detection circuit 52 is higher than the preset first current threshold, it may also determine that the T-type three-level three-phase rectification circuit is abnormal, such an embodiment may enable the controller 20 to determine that the T-type three-level three-phase rectification circuit is abnormal as early as possible, and because the controller 20 has more ways of determining whether the T-type three-level three-phase rectification circuit is abnormal, redundancy in the ways of determining the abnormality is also achieved, and stability of the scheme of the present application is further improved, for example, when the voltage detection circuit 10 fails, the embodiment of the present application may still achieve overvoltage protection for the capacitor.

In one embodiment of the present invention, the controller 20 is further configured to:

and after the T-shaped three-level three-phase rectification circuit is determined to be abnormal, controlling each switch tube in the A-phase T-shaped circuit, the B-phase T-shaped circuit and the C-phase T-shaped circuit to be in an off state.

In practical application, after determining that the T-type three-level three-phase rectification circuit is abnormal, the controller 20 controls the T-type three-level three-phase rectification circuit to be in a non-operating state through the execution unit 30, and in addition, the controller 20 can normally turn off the driving of each main switching tube in the circuit, that is, control each switching tube in the a-phase T-type circuit, the B-phase T-type circuit and the C-phase T-type circuit to be in an off state, so as to further ensure the safety of normal components in the T-type three-level three-phase rectification circuit.

By applying the technical scheme provided by the embodiment of the invention, the applicant considers the secondary fault condition of capacitor overvoltage caused by the fault of the transverse pipe in the T-shaped three-level three-phase rectification circuit, therefore, the voltage detection circuit is adopted to detect the voltage of the first capacitor and the voltage of the second capacitor, and the controller can determine whether the T-shaped three-level three-phase rectification circuit is abnormal or not according to the voltage of the first capacitor and the voltage of the second capacitor. If the T-shaped three-level three-phase rectification circuit is determined to be abnormal, the controller controls the T-shaped three-level three-phase rectification circuit to be in a non-working state through the execution unit. Therefore, when any one or more horizontal pipes of the T-shaped three-level three-phase rectifying circuit fail, the overvoltage protection mechanism can be timely found and triggered, namely the T-shaped three-level three-phase rectifying circuit is controlled to be in a non-working state, so that the situation that the printed board is exploded or even damaged due to overvoltage of the capacitor is avoided. In conclusion, the scheme of the application can effectively avoid the secondary fault condition of capacitor overvoltage caused by the fault of the transverse tube in the T-shaped three-level three-phase rectification circuit.

Corresponding to the above embodiments of the T-type three-level three-phase rectification circuit, embodiments of the present invention further provide a power converter, which may include the T-type three-level three-phase rectification circuit in any of the above embodiments, and reference may be made to the above corresponding embodiments, and description thereof is not repeated here.

It is further noted that, herein, relational terms such as first and second, and the like may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Also, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising an … …" does not exclude the presence of other identical elements in a process, method, article, or apparatus that comprises the element.

Those of skill would further appreciate that the various illustrative elements and algorithm steps described in connection with the embodiments disclosed herein may be implemented as electronic hardware, computer software, or combinations of both, and that the various illustrative components and steps have been described above generally in terms of their functionality in order to clearly illustrate this interchangeability of hardware and software. Whether such functionality is implemented as hardware or software depends upon the particular application and design constraints imposed on the implementation. Skilled artisans may implement the described functionality in varying ways for each particular application, but such implementation decisions should not be interpreted as causing a departure from the scope of the present invention.

The principle and the implementation of the present invention are explained in the present application by using specific examples, and the above description of the embodiments is only used to help understanding the technical solution and the core idea of the present invention. It should be noted that, for those skilled in the art, it is possible to make various improvements and modifications to the present invention without departing from the principle of the present invention, and those improvements and modifications also fall within the scope of the claims of the present invention.