KR20230128801A - 6 Level T-Type Active Neutral Clamping Inverter - Google Patents

Abstract

The present invention can increase the number of output levels compared to the prior art, reduce the number of devices compared to other topologies with the same number of levels, and solve the neutral point imbalance problem when using multiple DC link capacitors. It relates to a neutral point clamping inverter, which is a 6-level T-type active neutral point clamping inverter that can reduce the number of elements compared to the conventional multi-level inverter of the same level by integrating a conventionally used path selection circuit into a 4L-ANPC sub-circuit. it's about

Description

6 Level T-Type Active Neutral Clamping Inverter}

The present invention relates to a 6-level T-type active neutral point clamping inverter, and more specifically, by connecting a T-type inverter having a characteristic of selecting a current path to an end of an ANPC inverter, the number of voltage levels can be increased compared to conventional inverters. It is about a 6-level T-type active neutral point clamping inverter with a novel structure.

Compared to two-level converters, multi-level converters have lower voltage fluctuations, Total Harmonic Distortion (THD), reduced cut-off voltage of IGBTs, increased operating power range, and electromagnetic interference (Electro Magnetic Interference, EMI) mitigation. Numerous studies have been conducted to apply these multilevel converters to various topologies, modulation techniques and control schemes for various purposes such as motor drives, solar inverters and grid connection systems.

Existing topologies such as Neutral Point Clamped (NPC) inverters and Flying Capacitor Inverters (FCI) have been widely recognized, Active Neutral Point Clamped (ANPC) inverters and Hybrid-Clamped Inverters Inverter, HCI) has been further developed with various topological variants.

If the conventional 4-level hybrid clamp inverter structure is simplified by removing the flying capacitor, a 4-level active neutral point clamped (4L-ANPC) inverter can be obtained. This 4L-ANPC topology eliminates the need to control the voltage of the flying capacitor, which adversely affects capacitor voltage fluctuations and high harmonic distortion. At this time, the external circuit of the 4L-ANPC topology is used to adjust the DC link capacitor voltage. In this 4L-ANPC, an attempt has been made to eliminate an external circuit by injecting a zero sequence voltage and adjusting a duty cycle. However, this improvement comes at the expense of higher total harmonic distortion in the output voltage.

The 4L-ANPC with auxiliary balancing circuit has also been patented, applied and commercialized for uninterruptible power supply (UPS) applications in continuous configuration. Despite the improvements in reliability and efficiency of inverters of this technology, the lack of flying capacitors can be a problem when the input DC voltage needs to be increased and the inverter needs to be modified to a higher level. Using a higher DC link voltage at the same number of levels results in higher dv/dt values, increased output voltage total harmonic distortion, and higher device voltage stress, which affects the operating range and There are problems that limit its applicability.

Another way to overcome this limitation and increase the number of output levels is to utilize a path selector, which is a feature of the T-type inverter structure. Using the path selector, the connection and conduction paths between the different half-bridge sub-circuits and the output nodes of each phase leg can be established simply by selecting the corresponding active switch, in the present invention the path of the three-level T-type inverter (3L-T2I). A new topology of a new 6-level T-type active neutral point clamp inverter is proposed by integrating the selector structure into the 4L-ANPC subcircuit.

Korean Patent Publication No. 10-2018-0104842 ("3-level NPC inverter system having unbalanced capacitor voltage and its control method", published on September 27, 2018)

The present invention has been made to solve the above technical problems, and the purpose of the 6-level T-type active neutral point clamping inverter according to the present invention is to increase the number of output levels compared to the prior art, and to It is to provide a 6-level T-type active neutral point clamping inverter that can reduce the number of devices compared to the topology and solve the neutral point imbalance problem when using multiple DC link capacitors.

A 6-level T-type active neutral point clamping inverter according to the present invention for solving the technical problem as described above includes first to fifth capacitors connected in series with each other, and a DC link capacitor unit having both ends connected to a DC power supply. and first to third legs connected in parallel for each phase to the DC link capacitor unit, wherein each of the first to third legs has both ends connected to the first capacitor and is connected in series to each other and alternately switched. A first switch unit including a 1-1 switch and a 1-2 switch, both ends of which are connected to the third capacitor, and a 3-1 switch and a 3-2 switch that are connected in series and alternately switched A third switch unit including a third switch unit, both ends of which are connected to the fifth capacitor, and a fifth switch unit including a 5-1 switch and a 5-2 switch that are connected in series and alternately switched, one end of which is connected to the first The 2-1 switch and one end connected between the -1 switch and the 1-2 switch are connected between the 3-1 switch and the 3-2 switch, and alternately switch with the 2-1 switch. A second switch unit including a 2-2 switch and a 4-1 switch connected in series with the 2-2 switch, and one end connected between the 5-1 switch and the 5-2 switch However, it includes a fourth switch unit including a 4-2 switch that is alternately switched with the 4-1 switch, and an output end is connected to the other end of the 4-1 switch or the 2-2 switch, and the output It is characterized in that it further comprises a controller for controlling the switching of the first to fifth switch unit according to the desired voltage.

In addition, when the output voltage command for each phase is 0, the controller operates the 1-1 switch, the 2-1 switch, the 3-1 switch, the 4-1 switch, and the 5-1 switch. and controlling the 1-2 switch, the 2-2 switch, the 3-2 switch, the 4-2 switch and the 5-2 switch to be turned on.

In addition, the controller controls the 1-1 switch, the 2-1 switch, the 3-1 switch, and the 4-1 switch to be off when the output voltage command for each phase is in the first level range, , The 1-2 switch, the 2-2 switch, the 3-2 switch and the 4-2 switch are controlled to be on, and the 5-1 switch and the 5-2 switch are set to a predetermined duty. It is characterized in that switching is controlled by ratio.

In addition, the controller controls the 1-1 switch, the 2-1 switch, the 3-1 switch and the 5-2 switch to be off when the output voltage command for each phase is in the second level range, , The 1-2 switch, the 2-2 switch, the 3-2 switch and the 5-1 switch are controlled to be on, and the 4-1 switch and the 4-2 switch are set to a predetermined duty. It is characterized in that switching is controlled by ratio.

In addition, the controller controls the 1-1 switch, the 2-1 switch, the 4-2 switch and the 5-2 switch to be off when the output voltage command for each phase is in the third level range, , The 1-2 switch, the 2-2 switch, the 4-1 switch and the 5-1 switch are controlled to be on, and the 3-1 switch and the 3-2 switch are set to a predetermined duty. It is characterized in that switching is controlled by ratio.

In addition, the controller controls the 1-1 switch, the 3-2 switch, the 4-2 switch and the 5-2 switch to be off when the output voltage command for each phase is in the fourth level range, , The 1-2 switch, the 3-1 switch, the 4-1 switch and the 5-1 switch are controlled to be turned on, and the 2-1 switch and the 2-2 switch are set to a predetermined duty. It is characterized in that switching is controlled by ratio.

In addition, the controller controls the 2-2 switch, the 3-2 switch, the 4-2 switch and the 5-2 switch to be off when the output voltage command for each phase is in the 5th level range, , The 2-1 switch, the 3-1 switch, the 4-1 switch, and the 5-1 switch are controlled to be on, and the 1-1 switch and the 1-2 switch are set to a predetermined duty. It is characterized in that switching is controlled by ratio.

의 범위에 따라 아래 수식을 통해 결정되는 것을 특징으로 한다.In addition, the duty ratio of the first to fifth switch units is a normalized output voltage command for each phase.

It is characterized in that it is determined through the formula below according to the range of

는 x상의 제n스위치부의 듀티비)(here

is the duty ratio of the n-th switch unit on x)

는 아래 수식에 의해 결정되는 것을 특징으로 한다. Also, the above

Is characterized by being determined by the formula below.

In addition, it is characterized in that it further comprises a voltage balancing unit located between the DC power supply and the DC link capacitor unit to balance the voltages of the first to fifth capacitors.

In addition, the voltage balancing unit is connected in parallel with the DC power supply and the DC link capacitor unit, and is located between a sixth switch and a seventh switch connected in series with each other, and between the sixth switch and the seventh switch, A first diode limiting the direction to one side, one end connected between the sixth switch and the first diode, and the other end connected between the first capacitor and the second capacitor A first inductor, one end connected to the seventh A second inductor connected between a switch and the first diode and the other end connected between the fourth capacitor and the fifth capacitor, an eighth switch having one end connected to the other end of the first inductor, and one end connected to the second inductor. A ninth switch connected to the other end of the inductor and connected in series with the eighth switch, a second diode located between the eighth switch and the ninth switch, one end between the eighth switch and the second diode a third inductor having one end connected between the second capacitor and the third capacitor and one end connected between the ninth switch and the second diode, and the other end connected between the third capacitor and the fourth capacitor. It is characterized in that it comprises a fourth inductor connected to.

이 상기 직류 전원의 출력전압을 5로 나눈

보다 낮고, 상기 제3인덕터를 통해 흐르는 전류인

의 크기가 기준치인

이하이면 상기 제8스위치 및 상기 제9스위치를 온 제어하는 것을 특징으로 한다.In addition, the controller is a voltage of the third capacitor

Dividing the output voltage of the DC power supply by 5

is lower, and the current flowing through the third inductor is

is the standard value

If it is below, it is characterized in that the eighth switch and the ninth switch are turned on and controlled.

이 상기 직류 전원의 출력전압을 5로 나눈

보다 크거나, 상기 제3인덕터를 통해 흐르는 전류인

의 크기가 기준치인

를 초과하면, 상기 제8스위치 및 상기 제9스위치를 오프 제어하는 것을 특징으로 한다.In addition, the controller is a voltage of the third capacitor

Dividing the output voltage of the DC power supply by 5

greater than or equal to the current flowing through the third inductor.

is the standard value

If it exceeds, characterized in that the eighth switch and the ninth switch are off-controlled.

에서 상기

를 뺀 값을 비례-적분 제어해, 상기 제8스위치 및 상기 제9스위치의 듀티비

를 출력하는 것을 특징으로 한다.In addition, the controller

Remind from

The duty ratio of the eighth switch and the ninth switch is proportionally-integrated to the value subtracted from

It is characterized by outputting.

가 상기 직류 전원의 출력전압에 3/5를 곱한

보다 낮고, 상기 제1인덕터를 통해 흐르는 전류인

의 크기가 기준치인

이하이면 상기 제6스위치 및 상기 제7스위치를 온 제어하는 것을 특징으로 한다.In addition, the controller is the sum of the voltages of the second to fourth capacitors

is the output voltage of the DC power multiplied by 3/5

is lower, and the current flowing through the first inductor is

is the standard value

If it is below, it is characterized in that the sixth switch and the seventh switch are turned on and controlled.

가 상기 직류 전원의 출력전압에 3/5를 곱한

를 초과하거나, 상기 제1인덕터를 통해 흐르는 전류인

의 크기가 기준치인

를 초과하면 상기 제6스위치 및 상기 제7스위치를 오프 제어하는 것을 특징으로 한다.In addition, the controller is the sum of the voltages of the second to fourth capacitors

is the output voltage of the DC power multiplied by 3/5

Exceeds, or is the current flowing through the first inductor

is the standard value

When it exceeds, the sixth switch and the seventh switch are controlled to be turned off.

에서 상기

를 뺀 값을 비례-적분 제어해, 상기 제6스위치 및 상기 제7스위치의 듀티비

를 출력하는 것을 특징으로 한다.In addition, the controller

Remind from

The duty ratio of the sixth switch and the seventh switch is proportionally-integrated to the value obtained by subtracting

It is characterized by outputting.

In addition, the capacitance of each of the first to fifth capacitors is the same as each other.

According to the 6-level T-type active neutral point clamping inverter according to the present invention as described above, the number of elements is reduced compared to the conventional multi-level inverter of the same level by integrating the conventionally used path selection circuit into the 4L-ANPC sub-circuit. There are effects that can be done.

, 게이팅 신호 기준

및 스위칭 상태의 합인

를 도시한 것이고,
도 4는 순서대로 본 실시예에 의한 6L-TANPC에서 0, 제1레벨범위 ~ 제5레벨범위의 출력전압을 가질 때 경로를 도시한 것이며,
도 5는 도 1에서 전압 밸런싱부(300)만을 도시한 것이고,
도 6은 제어기에서 상기한 제6스위치(S6) ~ 제9스위치(S9)를 제어하는 과정의 제어블록도이며,
도 7은 고진폭 및 저진폭 및 주파수및 주파수 변조 지수에서 출력 전압, DC 링크 커패시터 전압 및 출력 전류의 파형의 그래프이고,
도 8은 변조 지수인 m이 각각 0.2, 0.4, 0.6, 0.8, 1로 낮은 값에서 높은 값으로 변할 때, 출력 선간전압, DC링크 커패시터부(100)의 전압 및 출력 상전류의 그래프이며,
도 9는 다양한 변조 지수에서 극 전압 및 선간 전압의 THD 값의 그래프이고,
도 10은 임피던스 부하에 급격한 변화가 가해질 때 이 인버터의 동작의 그래프이며,
도 11에는 직류 전원(10)이 일정하고,

가 각각 0.9 및 0.1인 조건에서 인버터의 출력 극 전압

와 선간 전압의 그래프이다.1 is a circuit diagram of a 6-level T-type active neutral point clamping inverter according to an embodiment of the present invention;
FIG. 2 shows only the DC link capacitor unit 100 and the first leg 200 of the 6L-TANPC inverter according to an embodiment of the present invention shown in FIG. 1,
3 shows the duty ratio in each of the first leg 200 to the third leg.

, based on the gating signal

and the sum of the switching states

is shown,
4 shows a path when the 6L-TANPC according to this embodiment has an output voltage of 0, the first level range to the fifth level range in sequence,
5 shows only the voltage balancing unit 300 in FIG. 1,
Figure 6 is a control block diagram of the process of controlling the sixth switch (S6) to the ninth switch (S9) in the controller,
7 is a graph of the waveforms of the output voltage, DC link capacitor voltage and output current at high and low amplitude and frequency and frequency modulation index;
8 is a graph of the output line voltage, the voltage of the DC link capacitor unit 100, and the output phase current when the modulation index m changes from a low value to a high value of 0.2, 0.4, 0.6, 0.8, and 1, respectively,
9 is a graph of THD values of pole voltage and line voltage at various modulation indices;
10 is a graph of the operation of this inverter when a sudden change in impedance load is applied;
11, the DC power supply 10 is constant,

The output pole voltage of the inverter under the condition that is 0.9 and 0.1, respectively.

and is the graph of the line-to-line voltage.

Hereinafter, a 6-level T-type active neutral point clamping inverter according to the present invention will be described in detail with reference to the accompanying drawings. Hereinafter, the terms inverter and inverter are used interchangeably.

1 is a circuit diagram of a 6-level T-type active neutral point clamping inverter according to an embodiment of the present invention.

As shown in FIG. 1, the 6-level T-type active neutral point clamping inverter according to an embodiment of the present invention largely includes a DC link capacitor unit 100, a first leg 200 to 3 legs, and a voltage balancing unit ( 300) may be included.

As shown in FIG. 1, the DC link capacitor unit 100 includes first capacitors C1 to fifth capacitors C5 connected in series with each other, and both ends are connected to the DC power supply 10.

The first leg 200 to the third leg are connected in parallel with the DC link capacitor unit 100 for each phase. In FIG. 1, only the first leg 200 is shown, and since the second leg and the third leg have the same configuration as the first leg 200, the description of the first leg 200 describes the second leg and the third leg. Replaces the description of the leg.

The voltage balancing unit 300 is located between the DC power supply 10 and the DC link capacitor unit 100 to balance the voltages of the first capacitor C1 to the fifth capacitor C5.

First, the first leg 200 will be described.

The first leg 200 utilizes 5 capacitors included in the DC link capacitor unit 100, and a 6-level T-type active neutral point clamping inverter (hereinafter referred to as a 6L-TANPC inverter) according to an embodiment of the present invention is a total 6 levels of output are possible.

FIG. 2 is an enlarged view of the DC link capacitor unit 100 and the first leg 200 of the 6L-TANPC inverter according to an embodiment of the present invention shown in FIG. 1 .

As shown in FIG. 2 , each of the first leg 200 to the third leg may include a first switch unit 210 to a fifth switch unit 250 and a controller (not shown).

The first switch unit 210 includes a 1-1 switch S11 and a 1-2 switch S12.

The 1-1 switch S11 and the 1-2 switch S12 are connected in series with each other, and the first switch unit 210 is connected in parallel with the first capacitor C1. That is, both ends of the first switch unit 210 are connected to both ends of the first capacitor C1. The 1-1 switch (S11) and the 1-2 switch (S12) operate complementary to each other, so when the 1-1 switch (S11) is turned on, the 1-2 switch (S12) is turned off , When the 1-1 switch (S11) is turned off, the 1-2 switch is turned on.

As shown in FIG. 2, both ends of the third switch unit 230 are connected to both ends of the third capacitor C3, and are connected in parallel with the third capacitor C3. The third switch unit 230 includes a 3-1 switch S31 and a 3-2 switch S32 connected in series to each other and operating complementarily.

As shown in FIG. 2, both ends of the fifth switch unit 250 are connected to both ends of the fifth capacitor C5 and connected in parallel with the fifth capacitor C5. The fifth switch unit 250 includes a 5-1 switch S51 and a 5-2 switch S52 connected in series to each other and operating complementarily.

The second switch unit 220 has a 2-1 switch S21 connected between the 1-1 switch S11 and the 1-2 switch S12 and one end connected to the 3-1 switch S31. It is connected between the 3-2 switches (S32) and includes a 2-2 switch (S22) that operates complementaryly with the 2-1 switch (S21).

The fourth switch unit 240 includes a 4-1 switch S41 connected in series with the 2-2 switch S22, one end of the 5-1 switch S51 and the 5-2 switch S52. Doedoe connected therebetween, may include a 4-2 switch (S42) that operates complementaryly with the 4-1 switch (S41).

2, among the 4-1 switch S41 and the 2-2 switch S22, the 4-1 switch S41 is located closer to the DC link capacitor unit 100 than the 2-2 switch S22. However, the present invention is not limited to the connection structure of the 4-1 switch (S41) and the 2-2 switch (S22), and the 2-2 switch (S22) is the 4-1 switch ( There may also be an embodiment located on the side of the DC link capacitor unit 100 rather than S41).

The other end of the 2-2 switch S22 is connected to the output end, and the output end may also be connected to the other ends of the 2-1 switch S21 and the 4-2 switch S42.

The controller controls the switching of the first switch unit 210 to the fifth switch unit 250 according to the voltage to be output.

The present invention has the circuit structure as described above, and unlike other topologies in the prior art, it is possible to output the same level of output voltage without using a flying capacitor or clamping diode. Therefore, the present invention can be used for devices with various rated voltages. In this case, there is an effect of using fewer components, and the table below compares the number of elements required to implement the conventional 6-level inverters and the 6L-TANPC according to the present invention.

Hereinafter, a method of switching each of the first switch unit 210 to the fifth switch unit 250 according to the output voltage command for each phase in the controller will be described.

은 아래 수식과 같이 정의된다고 가정한다.Assuming that the voltage of the DC link capacitor unit 100 is well regulated, the switching operation can be implemented with a simplified in-phase disposition (IPD) level shift carrier-based LS-PWM technology. Here, duty standards of a pair of switches included in each of the first switch unit 210 to the fifth switch unit 250 are compared with the carrier wave. First, the output voltage command for each phase

It is assumed that is defined as in the formula below.

(One)

,

,

및

는 각각 진폭 변조 지수, 주파수 변조 지수, 기본 각주파수 및 초기 위상각을 의미하며, x는 a, b, c 위상 각각을 의미할 수 있다. 진폭 변조 지수와 주파수 변조 지수의 범위는 0~1인 반면,

는 위상 a, b, c 각각에 대해 0도, -120도, -240도로 설정된다. 여기서 주파수 변조 지수는 기본 각주파수에 대한 단위 변조 지수를 나타낸다. 스위칭 상태에 따라 각 스위칭 장치의 듀티비는 아래 수식과 같이 결정될 수 있다.in the above formula

,

,

and

Means an amplitude modulation index, a frequency modulation index, a fundamental angular frequency, and an initial phase angle, respectively, and x may mean a, b, and c phases, respectively. While the amplitude modulation index and frequency modulation index range from 0 to 1,

is set to 0 degrees, -120 degrees, and -240 degrees for phases a, b, and c, respectively. Here, the frequency modulation index represents a unit modulation index for each fundamental angular frequency. Depending on the switching state, the duty ratio of each switching device may be determined as shown in the following equation.

(2)

(3)

(4)

(5)

(6)

(7)

는 x상 제n스위치부의 듀티비를 의미하며,

는 0~1 사이의 정규화된 기준 값을 의미한다.in the above formulas

Means the duty ratio of the x-phase n-th switch unit,

Means a normalized reference value between 0 and 1.

, 게이팅 신호 기준

및 스위칭 상태의 합인

를 보여준다. 제1스위치부(210) ~ 제5스위치부(250) 각각의 모든 쌍의 동작은 데드타임이 필요하며 , 데드 타임의 길이에 따라 실제 스위칭 상태

의 값은 두 스위칭 상태 사이의 정류 동안 데드 타임 효과로 인해,

에서 약간 변동할 수 있다.3 shows the duty ratio in each of the first leg 200 to the third leg.

, based on the gating signal

and the sum of the switching states

shows The operation of each pair of the first switch unit 210 to the fifth switch unit 250 requires a dead time, and the actual switching state according to the length of the dead time

The value of is due to the dead time effect during commutation between the two switching states,

may fluctuate slightly.

The on/off/switching control of the first switch unit 210 to the fifth switch unit 250 determined by Equations (3) to (7) is summarized in a table as follows.

가 -1 이상 -0.6미만으로, 0보다 큰 출력전압을 의미하고, 제2레벨범위는

가 -0.6 이상 -0.2미만으로, 제1레벨범위보다 큰 출력전압을 의미하며, 제3레벨범위는

가 -0.2 이상 0.2미만으로, 제2레벨범위보다 큰 출력전압을 의미하고, 제4레벨범위는

가 0.2 이상 0.6미만으로, 제3레벨범위보다 큰 출력전압을 의미하며, 제5레벨범위는

가 0.6 이상 1미만으로, 제4레벨범위보다 큰 출력전압을 의미한다. 또한, 상기한 표에서 0은 오프상태를 유지하고 있는 것을 의미하고, 1은 온 상태를 유지하고 있는 것을 의미한다. 단, 상기한 표에서는 제n-1스위치에 대해서만 설명되었으므로, 제n-2스위치는 제n-1스위치와 상보적으로 동작하므로, 반대 상태로 동작할 수 있다. 상기한 표에서

는 제n스위치부에 포함되는 한 쌍의 스위치들이 소정의 듀티비로 서로 상보적으로 스위칭 동작하는 것을 의미한다. In the uppermost row of the above table, 0 means when there is no output voltage, and the first level range is

is -1 or more and less than -0.6, which means an output voltage greater than 0, and the second level range is

is -0.6 or more and less than -0.2, which means an output voltage greater than the first level range, and the third level range is

is -0.2 or more and less than 0.2, which means an output voltage greater than the second level range, and the fourth level range is

is 0.2 or more and less than 0.6, which means an output voltage greater than the third level range, and the fifth level range is

is 0.6 or more and less than 1, which means an output voltage greater than the fourth level range. In addition, in the above table, 0 means that the OFF state is maintained, and 1 means that the ON state is maintained. However, since only the n-1 th switch is described in the above table, the n-2 th switch operates complementaryly with the n-1 th switch, so it can operate in the opposite state. in the above table

means that a pair of switches included in the n-th switch unit perform switching operations complementary to each other with a predetermined duty ratio.

Figure 4 shows the path when the output voltage ranges from 0, the first level range to the fifth level in the 6L-TANPC according to this embodiment in order.

Hereinafter, a control method of balancing the voltages of the first capacitor C1 to the fifth capacitor C5 included in the DC link capacitor unit 100 through the voltage balancing unit 300 in the attached controller will be described.

First, the capacitances of the first capacitor C1 to fifth capacitor C5 may be designed to be identical to each other, and the first capacitor C1 to fifth capacitor C5 may be adjusted at the same voltage command.

FIG. 5 is an enlarged view of only the voltage balancing unit 300 in FIG. 1 .

The voltage balancing unit 300 shown in FIG. 5 can be viewed as a combination of two balancing circuits for three capacitors.

As shown in FIG. 5, the voltage balancing unit 300 is connected in parallel to the DC power supply 10 and the DC link capacitor unit 100, and the sixth switch S6 and the seventh switch (S6) connected in series with each other S7), a first diode (D1) located between the sixth switch (S6) and the seventh switch (S7) to limit the direction of the current to one side, one end is between the sixth switch (S6) and the first diode (D1) A first inductor (L1), the other end of which is connected between the first capacitor (C1) and the second capacitor (C2), one end is connected between the seventh switch (S7) and the first diode (D1), The second inductor L2 having the other end connected between the fourth capacitor C4 and the fifth capacitor C5, the eighth switch S8 having one end connected to the other end of the first inductor L1, and one end connected to the second inductor L2. A ninth switch (S9) connected to the other end of the inductor (L2) and connected in series with the eighth switch (S8), and a second diode (D2) located between the eighth switch (S8) and the ninth switch (S9) ), one end is connected between the eighth switch (S8) and the second diode (D2), and the other end is connected between the second capacitor (C2) and the third capacitor (C3) third inductor (L3) and one end It may include a fourth inductor L4 connected between the ninth switch S9 and the second diode D2 and the other end connected between the third capacitor C3 and the fourth capacitor C4.

Among the components of the voltage balancing unit 300 described above, the controller controls the voltages of the first capacitor C1 to fifth capacitor C5 by controlling the sixth switch S6 to the ninth switch S9.

First, a method of controlling the voltage of the third capacitor C3 in the controller will be described.

이 직류 전원(10)의 출력전압을 5로 나눈

보다 낮고, 제3인덕터(L3)를 통해 흐르는 전류인

의 크기가 기준치인

이하이면 상기 제8스위치(S8) 및 상기 제9스위치(S9)를 온 제어한다. 여기서 제8스위치(S8)와 제9스위치(S9)는 소정 듀티비로 스위칭될 수 있다. 이러한 방식을 통해 제3커패시터(C3)는 충전되어,

에 가깝게 밸런싱될 수 있다.The controller is the voltage of the third capacitor (C3)

Dividing the output voltage of this DC power supply 10 by 5

is lower, and the current flowing through the third inductor (L3) is

is the standard value

If it is below, the eighth switch (S8) and the ninth switch (S9) are turned on. Here, the eighth switch S8 and the ninth switch S9 may be switched at a predetermined duty ratio. In this way, the third capacitor C3 is charged,

can be balanced close to

이 상기

보다 크거나, 제3인덕터(L3)를 통해 흐르는 전류인

의 크기가 기준치인

를 초과하면, 제8스위치(S8) 및 제9스위치(S9)를 오프 제어할 수 있다. 이러한 방식을 통해 제3커패시터(C3)는 방전되어,

에 가깝게 밸런싱될 수 있다.In addition, the controller is the voltage of the third capacitor (C3)

Remind this

greater than or equal to the current flowing through the third inductor L3.

is the standard value

If it exceeds, the eighth switch (S8) and the ninth switch (S9) can be off-controlled. Through this method, the third capacitor (C3) is discharged,

can be balanced close to

는 제어기가

에서 상기

를 뺀 값을 비례-적분 제어해 출력될 수 있다.In the above control process, the duty ratio of the eighth switch S8 and the ninth switch S9

is the controller

Remind from

The value subtracted from can be output by proportional-integral control.

The controller can control the voltages of the second capacitors C2 to fourth capacitors C4 separately from the voltage control of the third capacitor C3 described above.

가 직류 전원(10)의 출력전압에 3/5를 곱한

보다 낮고, 제1인덕터(L1)를 통해 흐르는 전류인

의 크기가 기준치인

이하이면 제6스위치(S6) 및 제7스위치(S7)를 온 제어할 수 있다. 여기서 온 제어란, 소정 듀티비로 스위칭되는 것을 의미할 수 있으며, 이를 통해 제2커패시터(C2) ~ 제4커패시터(C4)는 충전될 수 있다.The controller is the sum of the voltages of the second capacitor (C2) to the fourth capacitor (C4)

The output voltage of the DC power supply 10 is multiplied by 3/5

is lower, and the current flowing through the first inductor L1 is

is the standard value

Below, the sixth switch S6 and the seventh switch S7 can be turned on. The on control here may mean switching with a predetermined duty ratio, and through this, the second capacitor C2 to the fourth capacitor C4 can be charged.

가 직류 전원(10)의 출력전압에 3/5를 곱한

를 초과하거나, 제1인덕터(L1)를 통해 흐르는 전류인

의 크기가 기준치인

를 초과하면 제6스위치(S6) 및 제7스위치(S7)를 오프 제어할 수 있으며, 이를 통해 제2커패시터(C2) ~ 제4커패시터(C4)는 방전될 수 있다.In addition, the controller is the sum of the voltages of the second capacitor (C2) to the fourth capacitor (C4)

The output voltage of the DC power supply 10 is multiplied by 3/5

, or the current flowing through the first inductor L1.

is the standard value

If it exceeds, the sixth switch (S6) and the seventh switch (S7) can be controlled to be off, and through this, the second capacitor (C2) to the fourth capacitor (C4) can be discharged.

는 제어기가 상기

에서 상기

를 뺀 값을 비례-적분 제어해 출력할 수 있다.Duty ratios of the sixth switch S6 and the seventh switch S7 in the above-described control process.

is the controller

Remind from

The value subtracted from can be output through proportional-integral control.

Figure 6 is a control block diagram of a process of controlling the sixth switch (S6) to the ninth switch (S9) in the controller. As shown in FIG. 6, when the duty ratio of each of the sixth switch (S6) to the ninth switch (S9) is output, the sixth switch (S6) to the ninth switch ( S9) Each can be controlled.

In the present invention, simulations were performed to verify the proposed 6L-TANPC efficiency. The table below lists the simulation parameters for the 3-phase 6L-TANPC.

및

는 모두 m으로 표시되는 동일한 값으로 설정되어 있다고 가정한다. 단위 변조 지수(m=1)에서 극 전압은

와 같으며, 22%인 낮은 THD를 생성하는 반면 선간 전압 및 출력 상 전류의 THD는 13.52% 및 1.43%이다. 한편, m=0.2에서 이들 파형의 THD는 각각 104.80%, 71.07% 및 7.67%이다. 낮은 변조 지수에서 이러한 높은 THD 값은 레벨 수의 감소로 인해 다중 레벨 인버터에서 일반적이다.Figure 7 shows the waveforms of the output voltage, DC link capacitor voltage and output current at high and low amplitude and frequency modulation index. here

and

Assume that are all set to the same value denoted by m. At unit modulation index (m=1), the pole voltage is

, which produces a low THD of 22%, while the THD of line voltage and output phase current are 13.52% and 1.43%. On the other hand, the THD of these waveforms at m = 0.2 are 104.80%, 71.07% and 7.67%, respectively. At low modulation index, these high THD values are common in multi-level inverters due to the reduced number of levels.

The voltages of the first capacitor (C1) to the fifth capacitor (C5) are controlled by the voltage balancing unit 300 at the reference value E, where the highest peak value of the voltage ripple at the high and low modulation index is 5.27 of the reference value, respectively. % and 1.68%.

When the modulation index m changes from a low value to a high value of 0.2, 0.4, 0.6, 0.8, and 1, respectively, the output line voltage, the voltage of the DC link capacitor unit 100, and the output phase current are shown in FIG. As shown in FIG. 8, the voltage of the DC link capacitor unit 100 is maintained at a reference value with little variation.

9 shows THD values of pole voltage and line voltage at various modulation indices.

은 300kW에서 1.5MW로 증가하며, DC링크 커패시터부(100)의 최대 전압 리플은 2.82%에서 5.79%로 증가한다. 인버터가 m=0.2에서 동작되면 출력 전력이 13kW에서 65kW로 증가한다. 이 경우 DC링크 커패시터부(100)의 전압 리플은 각각 2.83% 및 3.42%이다. 이는 본 발명의 전압 밸런싱부(300)가 급격한 부하 변화에도 불구하고 변동이 적은 기준 전압(기준의 10% 미만)에서 DC링크 커패시터부(100)의 전압을 유지하는 것에 대해서 효과적임을 보여준다.Figure 10 shows the operation of this inverter when a sudden change in impedance load is applied. Here, the initial load is set to R=60Ω and L=6mH. Later, the load decreases to R = 12Ω and L = 1.2mH, increasing the output power to about 5 times higher than the initial condition. output power at unit modulation index

is increased from 300 kW to 1.5 MW, and the maximum voltage ripple of the DC link capacitor unit 100 increases from 2.82% to 5.79%. When the inverter is operated at m=0.2, the output power increases from 13kW to 65kW. In this case, the voltage ripples of the DC link capacitor unit 100 are 2.83% and 3.42%, respectively. This shows that the voltage balancing unit 300 of the present invention is effective for maintaining the voltage of the DC link capacitor unit 100 at a low fluctuation reference voltage (less than 10% of the reference voltage) despite rapid load changes.

A scaled-down 2-phase 6L-TANPC inverter is built for further verification, and the built inverter operates with the parameters listed in the table below.

가 각각 0.9 및 0.1인 조건에서 인버터의 출력 극 전압

와 선간 전압이 도시되어있다. 도 11a는

가 0.9일 때의 극 전압이고, 도 11b는

가 0.9일때의 선간 전압, 도 11c는

가 0.1일 때 극전압, 도 11d는

가 0.1일 때의 선간전압이다.

가 0.9 및 0.1인 두 경우 모두 기준 전압은

가 1일 때 생성된다. 또한, 출력 전압 파형도 시뮬레이션 결과의 파형과 유사하다.11, the DC power supply 10 is constant,

The output pole voltage of the inverter under the condition that is 0.9 and 0.1, respectively.

and the line-to-line voltage are shown. Figure 11a shows

is the pole voltage when is 0.9, and FIG. 11b shows

Line voltage when is 0.9, Figure 11c is

Pole voltage when is 0.1, Figure 11d

is the line-to-line voltage when is 0.1.

is 0.9 and 0.1, the reference voltage is

is created when is 1. Also, the waveform of the output voltage is similar to that of the simulation result.

In the present invention, a new topology of a 6-level T-type ANPC inverter (6L-TANPC) is proposed. By integrating the T-type structure into a 4-level ANPC inverter, the present invention increases the number of levels of the output voltage, resulting in lower voltage steps and harmonic voltage distortion in the output voltage. The effectiveness of this inverter was verified through simulation results in which the line-to-line voltage THD at unit modulation index was 13.52% and the maximum DC link capacitor voltage ripple was less than 10% of the reference value. The operation of this invention was also verified with a reduced prototype.

The present invention is not limited to the above embodiments, and the scope of application is diverse, and various modifications and implementations are possible without departing from the gist of the present invention claimed in the claims.

10: DC power
100: DC link capacitor unit
200: 1st leg
210 ~ 250: 1st switch part ~ 5th switch part
300: voltage balancing unit
C1 ~ C5: 1st capacitor ~ 5th capacitor
D1: 1st diode D2: 2nd diode
S11: 1-1 switch S12: 1-2 switch
S21: 2-1 switch S22: 2-2 switch
S31: 3-1 switch S32: 3-2 switch
S41: 4-1 switch S42: 4-2 switch
S51: 5-1 switch S52: 5-2 switch
S6: 6th switch S7: 7th switch
S8: 8th switch S9: 9th switch
L1 ~ L4: 1st inductor ~ 4th inductor

Claims (17)

In a 6-level T-type active neutral point clamping inverter that outputs any one of 0 voltage and 1st to 5th level voltages for each phase,
A DC link capacitor unit including first to fifth capacitors connected in series with each other, both ends of which are connected to a DC power source; and
first to third legs connected in parallel to the DC link capacitor unit for each phase;
Including,
Each of the first to third legs,
a first switch unit having both ends connected to the first capacitor and including a 1-1 switch and a 1-2 switch connected in series to each other and switched alternately;
a third switch unit including a 3-1 switch and a 3-2 switch, both ends of which are connected to the third capacitor, and which are connected in series and alternately switched;
a fifth switch unit including a 5-1 switch and a 5-2 switch, both ends of which are connected to the fifth capacitor, and which are connected in series and alternately switched;
The 2-1 switch having one end connected between the 1-1 switch and the 1-2 switch and the 2-1 switch having one end connected between the 3-1 switch and the 3-2 switch, a second switch unit including a 2-2 switch alternately switched with the switch; and
A 4-1 switch connected in series with the 2-2 switch, one end connected between the 5-1 switch and the 5-2 switch, and a switch alternately switched with the 4-1 switch. A fourth switch unit including a 4-2 switch;

a controller controlling the switching of the first to fifth switch units according to a voltage to be output;
including,
The 6-level T-type active neutral point clamping inverter, characterized in that the output terminal of the 6-level T-type active neutral point clamping inverter is connected to the other end of the 4-1 switch or the 2-2 switch.
According to claim 1,
The controller,
When the output voltage command for each phase is 0, the 1-1 switch, the 2-1 switch, the 3-1 switch, the 4-1 switch, and the 5-1 switch are controlled to be off, and the 6-level T-type active neutral point clamping characterized in that the 1-2 switch, the 2-2 switch, the 3-2 switch, the 4-2 switch and the 5-2 switch are controlled to be on. inverter.
According to claim 1,
The controller,
When the output voltage command for each phase is within the first level range, the 1-1 switch, the 2-1 switch, the 3-1 switch, and the 4-1 switch are controlled to be off, and the 1-1 switch is controlled to be turned off. Controlling the 2nd switch, the 2-2nd switch, the 3-2nd switch and the 4-2nd switch to be on, and switching and controlling the 5-1st switch and the 5-2nd switch at a predetermined duty ratio Features a 6-level T-shaped active neutral point clamping inverter.
According to claim 1,
The controller,
When the output voltage command for each phase is in the second level range, the 1-1 switch, the 2-1 switch, the 3-1 switch, and the 5-2 switch are controlled to be off, and the 1-2 The switch, the 2-2 switch, the 3-2 switch and the 5-1 switch are controlled to be turned on, and the 4-1 switch and the 4-2 switch are controlled to be switched at a predetermined duty ratio. 6-level T-shaped active neutral point clamping inverter.
According to claim 1,
The controller,
When the output voltage command for each phase is in the third level range, the 1-1 switch, the 2-1 switch, the 4-2 switch, and the 5-2 switch are controlled to be off, and the 1-2 switch is turned off. The switch, the 2-2 switch, the 4-1 switch and the 5-1 switch are controlled to be turned on, and the 3-1 switch and the 3-2 switch are controlled to be switched at a predetermined duty ratio. 6-level T-shaped active neutral point clamping inverter.
According to claim 1,
The controller,
When the output voltage command for each phase is in the fourth level range, the 1-1 switch, the 3-2 switch, the 4-2 switch, and the 5-2 switch are controlled to be turned off, and the 1-2 switch is turned off. The switch, the 3-1 switch, the 4-1 switch and the 5-1 switch are controlled to be turned on, and the 2-1 switch and the 2-2 switch are controlled to be switched at a predetermined duty ratio. 6-level T-shaped active neutral point clamping inverter.
According to claim 1,
The controller,
When the output voltage command for each phase is within the fifth level range, the 2-2 switch, the 3-2 switch, the 4-2 switch, and the 5-2 switch are controlled to be off, and the 2-1 switch is controlled to be off. The switch, the 3-1 switch, the 4-1 switch and the 5-1 switch are controlled to be turned on, and the 1-1 switch and the 1-2 switch are controlled to be switched at a predetermined duty ratio. 6-level T-shaped active neutral point clamping inverter.
According to any one of claims 3 to 7,
Each duty ratio of the first to fifth switch units for each phase is a normalized output voltage command for each phase.

6-level T-type active neutral point clamping inverter, characterized in that determined by the formula below according to the range of.

(here

is the duty ratio of the n-th switch unit on x)

According to claim 1,
a voltage balancing unit positioned between the DC power source and the DC link capacitor unit to balance voltages of the first to fifth capacitors;
A 6-level T-type active neutral point clamping inverter, characterized in that it further comprises.
According to claim 9,
The voltage balancing unit,
a sixth switch connected in parallel to the DC power supply and the DC link capacitor unit and connected in series to each other; and a seventh switch;
a first diode positioned between the sixth switch and the seventh switch to limit the direction of current to one side;
a first inductor having one end connected between the sixth switch and the first diode and the other end connected between the first capacitor and the second capacitor;
a second inductor having one end connected between the seventh switch and the first diode and the other end connected between the fourth capacitor and the fifth capacitor;
an eighth switch having one end connected to the other end of the first inductor;
a ninth switch having one end connected to the other end of the second inductor and connected in series with the eighth switch;
a second diode positioned between the eighth switch and the ninth switch;
a third inductor having one end connected between the eighth switch and the second diode and the other end connected between the second capacitor and the third capacitor; and
a fourth inductor having one end connected between the ninth switch and the second diode and the other end connected between the third capacitor and the fourth capacitor;
A 6-level T-type active neutral point clamping inverter comprising a.
According to claim 10,
The controller,
The voltage of the third capacitor

Dividing the output voltage of the DC power supply by 5

is lower, and the current flowing through the third inductor is

is the standard value

6-level T-type active neutral point clamping inverter, characterized in that for controlling the on of the eighth switch and the ninth switch.
According to claim 10,
The controller,
The voltage of the third capacitor

Dividing the output voltage of the DC power supply by 5

greater than or equal to the current flowing through the third inductor.

is the standard value

6-level T-type active neutral point clamping inverter, characterized in that for controlling off the eighth switch and the ninth switch.
According to claim 11,
The controller,
remind

Remind from

The duty ratio of the eighth switch and the ninth switch is proportionally-integrated to the value subtracted from

6-level T-type active neutral point clamping inverter, characterized in that for outputting.
According to claim 10,
The controller,
The sum of the voltages of the second to fourth capacitors

is the output voltage of the DC power multiplied by 3/5

is lower, and the current flowing through the first inductor is

is the standard value

6-level T-type active neutral point clamping inverter, characterized in that for controlling the on of the sixth switch and the seventh switch.
According to claim 10,
The controller,
The sum of the voltages of the second to fourth capacitors

is the output voltage of the DC power multiplied by 3/5

Exceeds, or is the current flowing through the first inductor

is the standard value

6-level T-type active neutral point clamping inverter, characterized in that for controlling off the sixth switch and the seventh switch.
According to claim 14,
The controller,
remind

Remind from

The duty ratio of the sixth switch and the seventh switch is proportionally-integrated to the value obtained by subtracting

6-level T-type active neutral point clamping inverter, characterized in that for outputting.
According to claim 1,
A 6-level T-type active neutral point clamping inverter, characterized in that the capacitance of each of the first to fifth capacitors is the same.