阅读说明：本技术 一种三电平拓扑anpc四象限运行调制方法 (Three-level topology ANPC four-quadrant operation modulation method ) 是由 刘永奎 曹立航 张新涛 于 2020-12-15 设计创作，主要内容包括：本发明公开了一种三电平拓扑ANPC四象限运行调制方法,方法是采用高频调制信号驱动功率器件的PWM驱动信号；零电平续流开始时,先使用1条短续流路径强迫换流,后再额外开通1条续流路径,均衡损耗；零电平续流结束时,先关断额外开通的续流路径,迫使电流重新从短续流路径续流；输出正/负电平时,适时开通箝位管,对两串联承压开关管进行可靠的双向箝位。调制方式一方面优化了零电平续流方式及续流回路,降低了功率器件开关损耗,均衡了整流、逆变及四象限运行时各种工况下功率器件的损耗分布,另一方面可靠箝位承压功率器件实现均压的优势,具有结构简单、实现方案灵活、功率变换效率高、四象限运行损耗均衡的特点。(The invention discloses a three-level topology ANPC four-quadrant operation modulation method, which adopts a high-frequency modulation signal to drive a PWM (pulse-width modulation) driving signal of a power device; when zero-level follow current starts, 1 short follow current path is used for forced commutation, and then 1 follow current path is additionally opened to balance loss; when the zero-level follow current is finished, the additionally-opened follow current path is firstly turned off, and the current is forced to follow the current from the short follow current path again; when positive/negative electricity is output, the clamping tube is switched on in time, and reliable bidirectional clamping is carried out on the two series pressure-bearing switch tubes. The modulation mode optimizes a zero-level follow current mode and a follow current loop, reduces the switching loss of the power device, balances the loss distribution of the power device under various working conditions during rectification, inversion and four-quadrant operation, and reliably clamps the pressure-bearing power device to realize the advantage of voltage sharing.)

1. A three-level topology ANPC four-quadrant operation modulation method is characterized by comprising the following steps:

driving a PWM driving signal of a power device by adopting a high-frequency modulation signal;

when zero-level follow current starts, a short follow current path is used for forced commutation, and then a follow current path is additionally opened to balance loss;

when the zero-level follow current is finished, the additionally-opened follow current path is firstly turned off, and the current is forced to follow the current from the short follow current path again;

when positive/negative electricity is output, the clamping tube is switched on in time, and reliable bidirectional clamping is carried out on the two series pressure-bearing switch tubes.

2. The three-level topology ANPC four-quadrant operation modulation method of claim 1, wherein the three-level topology ANPC comprises six power devices, the six power devices respectively comprise a switch tube G1 and a diode D1, a switch tube G2 and a diode D2, a switch tube G3 and a diode D3, a switch tube G4 and a diode D4, a switch tube G5 and a diode D5, and a switch tube G6 and a diode D6.

3. The three-level topology ANPC four-quadrant operation modulation method of claim 2, wherein zero-level free-wheeling starts, and a dead time T is delayed after a switching tube G1/a switching tube G4 are turned off₁First, switch tube G5 and switch tube are turned onG6, when current flows through diode D2, diode D1 and freewheels to the positive bus, the free-wheeling path is forced to change from diode D2, diode D1 to diode D2, switch tube G5, and freewheels to the neutral point; when current flows through the diode D4 and the diode D3 and freewheels to the negative bus, the freewheeling path is forced to change from the diode D4 and the diode D3 into the switch tube G6 and the diode D3, and then the current freewheels to the neutral point; then delaying a dead time T₂The switching tube G2 and the switching tube G3 are switched on, and the diode D5, the switching tube G2, the switching tube G3 and the diode D6 are additionally switched on.

4. The three-level topology ANPC four-quadrant operation modulation method as claimed in claim 2, wherein when the zero-level follow current is finished, the switching tube G2 and the switching tube G3 are turned off first, and a dead time T is delayed₃Then the switch tube G5 and the switch tube G6 are turned off, and a dead time T is delayed₄Then, the switch tube G1/switch tube G4 are turned on, and the zero level follow current state is exited.

5. The three-level topology ANPC four-quadrant operation modulation method of claim 2, wherein the output positive/negative level is delayed by a dead time T after switching tube G1/switching tube G4 are turned on₁Switching on a switch tube G6/a switch tube G5 tube, and carrying out voltage-sharing clamping on a switch tube G3, a switch tube G4/a switch tube G1 and a switch tube G2 tube; before the switch tube G1/switch tube G4 is turned off, the dead time T is advanced₄The tube G6/G5 is turned off.

6. The three-level topology ANPC four-quadrant operation modulation method of claim 1, wherein the high frequency modulation signal frequency is 6 kHz-20 kHz.

7. The three-level topology ANPC four-quadrant operation modulation method of claim 2, wherein the three-level topology ANPC comprises two capacitors and a plurality of power devices; two capacitors connected in series are arranged on the direct current side in series; the power device comprises a switching tube and an anti-parallel diode thereof;

the first power device, the second power device, the third power device and the fourth power device are sequentially connected in series, the first power device is connected with the positive end of the first capacitor, and the fourth power device is connected with the negative end of the second capacitor;

the fifth power device and the sixth power device are connected in parallel, the middle points of the fifth power device and the sixth power device are connected with the middle points of the two capacitors, and the fifth power device and the sixth power device are respectively connected with the middle points of the first power device and the second power device and the middle points of the third power device and the fourth power device;

the middle points of the second power device and the third power device are connected with the AC end of the output point.

8. The three-level topology ANPC four-quadrant operation modulation method of claim 1, wherein the power device is an IGBT or a MOSFET.

Technical Field

The invention belongs to the technical field of power electronics, relates to a PWM (pulse-width modulation) technology of an ANPC (analog to digital converter) power circuit topology, and particularly relates to a three-level topology ANPC four-quadrant operation modulation method.

Background

Due to the rapid development of power electronic technology, multilevel technology is increasingly widely used, wherein diode clamped (NPC) three-level technology is the most commonly used power electronic power conversion technology in low-voltage (below 3 kV) applications. The structure can be more compact and lower in cost without using a transformer, but the structure has the problem of unbalanced loss of power devices (mainly IGBT), so that the improvement of the system capacity is limited, and in addition, the integration degree of the power devices is very high in consideration of factors such as cost and the like, and once the loss is unbalanced, the stability of the system is seriously influenced.

In order to solve the problem, an Active Neutral Point Clamped (ANPC) type three-level technology has attracted more and more attention and is applied in recent years, and the structure can realize the balance of the loss of the power device and has great advantages.

At present, the application of the ANPC three-level technology is mainly focused on the field of new energy, the PWM method only needs to consider loss balance under inversion application, and the application under rectification and four-quadrant conditions is less considered.

Disclosure of Invention

The invention provides a three-level topology ANPC four-quadrant operation modulation method aiming at the explanation of the background technology, and the invention is a PWM modulation method which can effectively balance the loss of each power device when the three-level topology ANPC operates under the condition of four quadrants, and effectively solves the problem of balance of the loss of each power device under the condition of four-quadrant operation.

In order to achieve the purpose, the invention provides the following technical scheme:

a three-level topology ANPC four-quadrant operation modulation method comprises the following steps:

driving a PWM driving signal of a power device by adopting a high-frequency modulation signal;

when zero-level follow current starts, a short follow current path is used for forced commutation, and then a follow current path is additionally opened to balance loss;

when the zero-level follow current is finished, the additionally-opened follow current path is firstly turned off, and the current is forced to follow the current from the short follow current path again;

when positive/negative electricity is output, the clamping tube is switched on in time, and reliable bidirectional clamping is carried out on the two series pressure-bearing switch tubes.

As a further improvement of the present invention, the three-level topology ANPC includes six power devices, and the six power devices respectively include a switch tube G1 and a diode D1, a switch tube G2 and a diode D2, a switch tube G3 and a diode D3, a switch tube G4 and a diode D4, a switch tube G5 and a diode D5, a switch tube G6 and a diode D6.

As a further improvement of the invention, zero level free-wheeling begins, and a dead time T is delayed after the switch tube G1/switch tube G4 is turned off₁When current flows through the diode D2 and the diode D1 and then flows to the positive bus, the switch tube G5 and the switch tube G6 are turned on, and the current forcibly flows to the neutral point after the diode D2 and the diode D1 are changed into the diode D2 and the switch tube G5; when current flows through the diode D4 and the diode D3 and freewheels to the negative bus, the freewheeling path is forced to change from the diode D4 and the diode D3 into the switch tube G6 and the diode D3, and then the current freewheels to the neutral point; then delaying a dead time T₂The switching tube G2 and the switching tube G3 are switched on, and the diode D5, the switching tube G2, the switching tube G3 and the diode D6 are additionally switched on.

As a further improvement of the invention, when the zero level follow current is finished, the switch tube G2 and the switch tube G3 are turned off first, and a dead time T is delayed₃Then the switch tube G5 and the switch tube G6 are turned off, and a dead time T is delayed₄Then, the switch tube G1/switch tube G4 are turned on, and the zero level follow current state is exited.

As a further improvement of the invention, the positive/negative output level is delayed by a dead time T after the switch tube G1/switch tube G4 are conducted₁Switching on a switch tube G6/a switch tube G5 tube, and carrying out voltage-sharing clamping on a switch tube G3, a switch tube G4/a switch tube G1 and a switch tube G2 tube; before the switch tube G1/switch tube G4 is turned off, the dead time T is advanced₄The tube G6/G5 is turned off.

As a further improvement of the invention, the frequency of the high-frequency modulation signal is 6 kHz-20 kHz.

As a further improvement of the present invention, the three-level topology ANPC includes two capacitors and a plurality of power devices; two capacitors connected in series are arranged on the direct current side in series; the power device comprises a switching tube and an anti-parallel diode thereof;

the first power device, the second power device, the third power device and the fourth power device are sequentially connected in series, the first power device is connected with the positive end of the first capacitor, and the fourth power device is connected with the negative end of the second capacitor;

the fifth power device and the sixth power device are connected in parallel, the middle points of the fifth power device and the sixth power device are connected with the middle points of the two capacitors, and the fifth power device and the sixth power device are respectively connected with the middle points of the first power device and the second power device and the middle points of the third power device and the fourth power device;

the middle points of the second power device and the third power device are connected with the AC end of the output point.

As a further improvement of the invention, the power device is an IGBT or a MOSFET.

Compared with the prior art, the invention has the beneficial effects that:

the method provided by the invention considers the working condition of four-quadrant operation, optimizes a zero-level follow current mode and a follow current loop, reduces the switching loss of the power device, balances the loss distribution of the power device when the four-quadrant operation voltage and current are in different phases, opens the clamping tube when outputting positive/negative voltage, reliably carries out bidirectional voltage sharing on the pressure-bearing series power device, and has the characteristics of simple structure, flexible implementation scheme, high power conversion efficiency and balanced loss of the power device during four-quadrant operation.

The invention discloses a three-level Active Neutral Point Clamped (ANPC) power circuit topology, and relates to a PWM signal modulation method driven by a power device with four-quadrant operation capability. All power devices in the modulation method are driven by high-frequency modulation signals, when current flows in a zero level state, the switch tube G5 and the switch tube G6 are turned on first, and a short current-flowing path is adopted, so that the switching loss of the power devices is reduced, and the efficiency is improved; and then the switch tube G2 and the switch tube G3 are switched on, 1 zero-level follow current loop is additionally switched on, and the losses of different power devices are well balanced. When outputting positive/negative voltage, the switch tube G6/switch tube G5 is turned on in due time, and the voltages borne by the switch tube G3, switch tube G4/switch tube G1 and switch tube G2 are reliably clamped. Compared with other modulation modes which are more applied at present, the modulation method optimizes a zero-level follow current mode and a follow current loop, reduces the switching loss of the power device, balances the loss distribution of the power device under various working conditions during rectification, inversion and four-quadrant operation, keeps the conduction of the switching tube G5 and the switching tube G6 when the three-level topology ANPC outputs positive/negative voltage, reliably clamps a pressure-bearing power device to realize the advantage of voltage sharing, and has the characteristics of simple structure, flexible realization scheme, high power conversion efficiency and balanced four-quadrant operation loss.

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, and 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 these drawings without creative efforts.

FIG. 1 is a schematic diagram of an ANPC three-level power circuit topology;

FIG. 2 is a schematic diagram of zero level freewheeling;

FIG. 3 is a schematic of positive/negative level active clamping; (a) positive level active clamping, (b) negative level active clamping;

FIG. 4 is a schematic diagram of a power device PWM modulation signal;

fig. 5 is a modulation signal dead zone diagram.

Detailed Description

The technical solutions of the present invention will be described clearly and completely with reference to the accompanying drawings, and it is obvious that the described embodiments are only some embodiments of the present invention, not all embodiments. 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.

As shown in fig. 1, a three-level topology ANPC includes two capacitors and a plurality of power devices; two capacitors connected in series are arranged on the direct current side in series; the power device comprises a switching tube and an anti-parallel diode thereof;

two capacitors (C1, C2) connected in series, four switching tubes (switching tube G1, switching tube G2, switching tube G3, switching tube G4) connected with two ends of the two capacitors and anti-parallel diodes (diode D1, diode D2, diode D3, diode D4) of the switching tubes, two switching tubes (switching tube G5, switching tube G6) connected with midpoints of the two capacitors (C1, C2) and anti-parallel diodes (diode D5, diode D6) of the switching tubes;

the first power device, the second power device, the third power device and the fourth power device are sequentially connected in series, the first power device is connected with the positive end of the first capacitor, and the fourth power device is connected with the negative end of the second capacitor;

the fifth power device and the sixth power device are connected in parallel, the middle points of the fifth power device and the sixth power device are connected with the middle points of the two capacitors, and the fifth power device and the sixth power device are respectively connected with the middle points of the first power device and the second power device and the middle points of the third power device and the fourth power device;

the middle points of the second power device and the third power device are connected with the AC end of the output point.

According to the three-level topology ANPC four-quadrant operation modulation method, PWM driving signals of all power devices are driven by high-frequency modulation signals, and a high-frequency switch tube and a power-frequency switch tube are not distinguished. When zero-level follow current starts, 1 short follow current path is used for forced commutation, and then 1 follow current path is additionally opened to balance loss; when the zero-level follow current is finished, the additionally opened follow current path is firstly turned off, and the current is forced to follow the current from the short follow current path. When positive/negative electricity is output, the clamping tube is switched on in time, and reliable bidirectional clamping is carried out on the two series pressure-bearing switch tubes.

The four-quadrant operation means that the phase difference between the phase of the AC side voltage and the actual current can be changed at will within a range of 0 to 360 degrees, and is not limited to rectification or inversion (i.e., the voltage and the current are in phase or in phase opposition).

The high frequency modulation signal is relative to the power frequency of 50Hz, and the actually used switching frequency depends on the switching characteristics of the power device and the requirements of the actual application.

When the zero level free-wheeling state begins, a dead time T is delayed after the switching tube G1/switching tube G4 is turned off_D14The switch tube G5 and the switch tube G6 are turned on first, and follow current is changed from positive and negative bus bars into follow current to a neutral point; then delaying a dead time T_U23And a switch tube G2 and a switch tube G3 are switched on, and a follow current loop is additionally provided, so that two follow current loops are ensured to be available in a zero-level follow current steady state when the four-quadrant operating voltage and current phase change occurs, and the loss of a power device is balanced.

When the zero level freewheeling state is finished, the switching tube G2 and the switching tube G3 are turned off first, and a dead time T is delayed_D23Then the switch tube G5 and the switch tube G6 are turned off, and a dead time T is delayed_U14Then, the switch tube G1/the switch tube G4 are switched on, the zero-level follow current state is quitted, and the on-off sequence of each switch tube is ensured to be consistent.

Delaying a dead time T after the switching tube G1/switching tube G4 tube conducts and outputs the positive/negative level_clampSwitching on a switch tube G6/a switch tube G5 tube, and carrying out voltage-sharing clamping on a switch tube G3, a switch tube G4/a switch tube G1 and a switch tube G2 tube respectively; before the switch tube G1/switch tube G4 is turned off, the dead time T is advanced_clampThe tube G6/G5 is turned off.

When the current flows at zero level, the switch tube G5 and the switch tube G6 are switched on and off simultaneously and controlled by the same modulation signal.

When the positive voltage is output, the switching tube G6 is switched on to carry out voltage-sharing clamping on the switching tube G3 and the switching tube G4, and the switching tube G5 is in an off state; when the output negative level is normal, the switch tube G5 is turned on to perform voltage-sharing clamping on the switch tube G1 and the switch tube G2, and the switch tube G6 is in an off state at the moment.

When the positive/negative voltage is output, the switch tube G2/the switch tube G3 are always in a conducting state, and a follow current path is ensured.

The present invention will be described in detail with reference to specific examples.

Examples

According to the illustration of fig. 1, the modulation method of the present invention is suitable for controlling the on/off of three-level topology ANPC6 power devices G1-switching tube G6 in the figure, thereby realizing power conversion. According to the three-level topology ANPC four-quadrant operation modulation method, when current flows in a zero-level state, the switch tube G5 and the switch tube G6 are turned on first, and current flows by using 1 short current-flowing path; and then the switch tube G2 and the switch tube G3 are switched on, and 1 additional follow current loop is switched on. When outputting positive/negative voltage, the switch tube G6/switch tube G5 is turned on in due time, and the voltages borne by the switch tube G3, switch tube G4/switch tube G1 and switch tube G2 are reliably clamped.

According to fig. 2, the zero-level free-wheeling can be divided into 4 conditions as shown. Wherein the positive half cycle of the voltage means that the voltage at the AC end of the output point is at a positive level V_DCAnd zero level V_ACWithin a half power frequency period of the/2 switching; the negative half cycle of the voltage means that the voltage at the AC end of the output point is at a negative level 0 and a zero level V_ACWithin half the power frequency period of the/2 switching. The positive half cycle of current means that current flows out of the AC end; the negative half cycle of current means that current flows from the AC terminal.

Under the working condition that the voltage is positive, the current flows out along the path of a solid line in the figure when the current is positive, when the switching tube G1 is turned off and enters a zero-level follow current state, the current can be automatically switched into the follow current loop 1, and the diode D5 is used for follow current along the short follow current path. After a dead time is delayed, the switching tube G5 and the switching tube G6 are conducted, at the moment, the freewheeling circuit 2 is additionally opened, namely freewheeling is conducted through the switching tube G6 and the diode D3, two paths in a zero level state can be guaranteed to carry out freewheeling, and loss of each power device is balanced.

Under the working condition of voltage negative half cycle and current negative half cycle, current flows in according to the path of a solid line in the figure, when the switching tube G4 is turned off and enters a zero-level follow current state, the current can be automatically switched into the follow current loop 1, and the diode D5 is used for carrying out short follow current path follow current. After a dead time is delayed, the switching tube G5 and the switching tube G6 are conducted, at the moment, the freewheeling circuit 2 is additionally switched on, namely freewheeling is realized through the diode D2 and the switching tube G5, two paths in a zero level state can be ensured to carry out freewheeling, and the loss of each power device is balanced.

Working condition (c) when the voltage is positive, the half cycle and the current is negative, the current still flows into the positive bus from the diode D2 and the diode D1 freewheeling diode, the switch tube G5 and the switch tube G6 are conducted after a dead time is delayed, the current can be switched to the freewheeling circuit 1 and becomes the freewheeling of the diode D2 and the switch tube G5, and the current flows into a neutral point; and after delaying a dead time, the switching tube G2 and the switching tube G3 are conducted, and at the moment, the freewheeling circuit 2 is additionally switched on, namely freewheeling is realized through the switching tube G3 and the diode D6, so that two paths in a zero level state can carry out freewheeling, and the loss of each power device is balanced.

Under the working condition of voltage negative half-cycle and current positive half-cycle, current still flows out of a negative bus from a diode D4 and a diode D3 freewheeling diode, a switch tube G5 and a switch tube G6 are conducted after a dead time is delayed, the current is switched to a freewheeling circuit 1 and becomes a freewheeling current of a switch tube G6 and a diode D3, and the current flows out of a neutral point; after a dead time is delayed, the switching tube G2 and the switching tube G3 are conducted, at the moment, the freewheeling circuit 2 is additionally switched on, namely freewheeling is realized through the diode D5 and the switching tube G2, two paths in a zero level state can be ensured to carry out freewheeling, and the loss of each power device is balanced.

According to fig. 3, when the positive/negative output voltage levels are outputted, the switching tube G6/the switching tube G5 are respectively turned on to perform voltage-sharing clamping on the pressure-bearing power device.

When the output positive voltage is normal, the switch tube G1 and the switch tube G2 are conducted, and at the moment, the switch tube G3 and the switch tube G4 are connected in series to bear the full bus voltage V_DCAfter the switch tube G1 and the switch tube G2 are conducted and delay a dead time, the switch tube G6 is turned on, and at the moment, the connection point of the switch tube G3 and the switch tube G4 is reliably clamped to the neutral point V_DCAnd/2, the bus voltage is divided equally.

When the output negative voltage is normal, the switch tube G3 and the switch tube G4 are conducted, and at the time, the switch tube G1 and the switch tube G2 are connected in series to bear the full bus voltage V_DCAfter the switch tube G3 and the switch tube G4 are conducted and delay a dead time, the switch tube G5 is turned on, and at the moment, the switch tube G1 and the switch tube G are conducted2 the connection point is reliably clamped to the neutral point V_DCAnd/2, the bus voltage is divided equally.

According to the fig. 4 and 5, the switching tube G1, the switching tube G3 and the switching tube G5 are switched on and off at the switching frequency when the voltage is positive for half a cycle, the switching tube G1 is complementary with the switching tube G3 and the switching tube G5, and the switching tube G1 is switched off and is switched on by the switching tube G5 with a dead time T_D14The difference between the on-state of the switch tube G5 and the on-state of the switch tube G3 is a dead time T_U23The switch tube G3 is turned off and the switch tube G5 is turned off by a dead time T_D23The switch tube G5 is turned off and the switch tube G1 is turned on by a dead time T_U14. When a positive level is output during the positive half cycle, the difference of the dead time T between the turn-on of the switching tube G6 and the turn-on of the switching tube G1, and the turn-off of the switching tube G6 and the turn-off of the switching tube G1 is_clampSimilarly, the voltage is negative for half cycle, and is not described again.

All articles and references disclosed above, including patent applications and publications, are hereby incorporated by reference for all purposes. The term "consisting essentially of …" describing a combination shall include the identified element, ingredient, component or step as well as other elements, ingredients, components or steps that do not materially affect the basic novel characteristics of the combination. The use of the terms "comprising" or "including" to describe combinations of elements, components, or steps herein also contemplates embodiments that consist essentially of such elements, components, or steps. By using the term "may" herein, it is intended to indicate that any of the described attributes that "may" include are optional.

A plurality of elements, components, parts or steps can be provided by a single integrated element, component, part or step. Alternatively, a single integrated element, component, part or step may be divided into separate plural elements, components, parts or steps. The disclosure of "a" or "an" to describe an element, ingredient, component or step is not intended to foreclose other elements, ingredients, components or steps.

It is to be understood that the above description is intended to be illustrative, and not restrictive. Many embodiments and many applications other than the examples provided would be apparent to those of skill in the art upon reading the above description. The scope of the present teachings should, therefore, be determined not with reference to the above description, but should instead be determined with reference to the appended claims, along with the full scope of equivalents to which such claims are entitled. The disclosures of all articles and references, including patent applications and publications, are hereby incorporated by reference for all purposes. The omission in the foregoing claims of any aspect of subject matter that is disclosed herein is not intended to forego such subject matter, nor should the applicant consider that such subject matter is not considered part of the disclosed subject matter.