阅读说明：本技术 一种anpc型三电平逆变器的关机方法、系统及装置 (Shutdown method, system and device of ANPC type three-level inverter ) 是由 陈建明 吴龙生 杨�一 柳传宝 卢钢 于 2021-11-03 设计创作，主要内容包括：本申请公开了一种ANPC型三电平逆变器的关机方法、系统及装置,该关机方法包括：采样ANPC型三电平逆变器的逆变电流和输出电压；当收到关机信号,根据逆变电流和输出电压计算电流过零点时刻,关断第一半桥模块中的高频开关管；等待预设时间段,开通第二半桥模块中的第二高频开关管；在电流过零点时刻,关断第一半桥模块中的低频开关管；等待预设时间段,关断第二半桥模块中的第二高频开关管。本申请在收到关机信号时,根据逆变电流和输出电压确定电流过零点时刻,并规定了所有开关管的动作时刻,从而保证不会在电流过零时发生换相,确保了所有开关管在安全范围内工作,使得逆变器能够可靠关机。(The application discloses a shutdown method, a shutdown system and a shutdown device of an ANPC type three-level inverter, wherein the shutdown method comprises the following steps: sampling the inversion current and the output voltage of the ANPC type three-level inverter; when a shutdown signal is received, calculating the zero crossing point moment of current according to the inverter current and the output voltage, and turning off a high-frequency switching tube in the first half-bridge module; waiting for a preset time period, and turning on a second high-frequency switching tube in the second half-bridge module; turning off a low-frequency switching tube in the first half-bridge module at the moment of current zero crossing; and waiting for a preset time period, and turning off a second high-frequency switching tube in the second half-bridge module. When the shutdown signal is received, the zero crossing point time of the current is determined according to the inverter current and the output voltage, and the action time of all the switching tubes is specified, so that the phase change can not occur when the current crosses zero, the working of all the switching tubes in a safety range is ensured, and the inverter can be reliably shut down.)

1. A shutdown method of an ANPC type three-level inverter is characterized in that the ANPC type three-level inverter comprises an upper half-bridge module and a lower half-bridge module, each half-bridge module comprises a low-frequency switching tube and two high-frequency switching tubes with complementary pulses, the two high-frequency switching tubes with complementary pulses comprise a first high-frequency switching tube and a second high-frequency switching tube, the first end of the low-frequency switching tube and the first ends of the two high-frequency switching tubes are connected, the second end of the low-frequency switching tube serves as an output end of the ANPC type three-level inverter, the second end of the first high-frequency switching tube is connected with a positive electrode or a negative electrode of a bus, and the second end of the second high-frequency switching tube is connected with a midpoint of the bus, and the shutdown method comprises the following steps:

sampling the inversion current and the output voltage of the ANPC type three-level inverter;

when a shutdown signal is received, calculating the zero crossing point moment of current according to the inverter current and the output voltage, and shutting down the high-frequency switching tube in the first half-bridge module;

waiting for a preset time period, and turning on the second high-frequency switching tube in the second half-bridge module;

turning off the low-frequency switching tube in the first half-bridge module at the moment of the current zero crossing point;

waiting for the preset time period, and turning off the second high-frequency switching tube in the second half-bridge module;

wherein the first half-bridge module is: before the shutdown signal is received, the high-frequency switch tube works in the half-bridge module, and the second half-bridge module is the other half-bridge module.

2. The shutdown method according to claim 1, wherein when the shutdown signal is a normal shutdown signal, the calculating a current zero-crossing time according to the inverter current and the output voltage includes:

calculating a first delay time duration according to a first formula, the first formula comprising:

；

whereinFor the first delay time period,the load inductor is connected with the output end;the current change amount of the inverter current is from the moment when the high-frequency switch tube in the first half-bridge module is turned off to the current zero crossing point;is composed ofA voltage variation of the corresponding output voltage;

determining the current zero-crossing time as: and waiting for the time after the first delay time from the turning off of the high-frequency switch tube in the first half-bridge module.

3. The shutdown method according to claim 2, wherein the process of turning off the high-frequency switching tube in the first half-bridge module comprises:

judging whether the current inverter current is larger than a threshold value;

if not, the high-frequency switching tube in the first half-bridge module is directly turned off;

if so, controlling the first half-bridge module until the current inverter current is not greater than the threshold value, and then turning off the high-frequency switching tube in the first half-bridge module.

4. The shutdown method according to claim 1, wherein, when the shutdown signal is an emergency shutdown signal, said calculating a current zero-crossing time according to the inverter current and the output voltage comprises:

according to the inverter current and the output voltage, calculating the maximum current value of the inverter current after the action of turning off the high-frequency switching tube in the first half-bridge module;

calculating a second delay time length for the inverter current to be reduced from the maximum current value to zero;

determining the current zero-crossing time as: and waiting for the time after the second delay time length from the time when the inverter current reaches the maximum current value.

5. The shutdown method according to claim 4, wherein said calculating a maximum current value of the inverter current after the action of turning off the high-frequency switching tube in the first half-bridge module according to the inverter current and the output voltage comprises:

calculating the maximum current value of the inverter current after the action of turning off the high-frequency switching tube in the first half-bridge module according to a second formula, wherein the second formula comprises the following steps:

；

whereinFor the said maximum current value, the current value is,for the inverter current upon receipt of the shutdown signal,as in the DC offset curve equationA corresponding offset value;the voltage variation of the output voltage is the voltage variation from the time when the shutdown signal is received to the time when the inverter current reaches the maximum current value;the system is delayed.

6. The shutdown method according to claim 5, wherein said calculating a second delay time duration for said inverter current to decrease from said maximum current value to zero comprises:

calculating a second delay time duration for the inverter current to decrease from the maximum current value to zero according to a third formula, where the third formula includes:

；

wherein the content of the first and second substances,is the second delay time length;and outputting the voltage variation of the output voltage from the moment when the inverter current reaches the maximum current value to the current zero-crossing point.

7. The shutdown method according to claim 1, wherein said calculating a current zero-crossing time according to the inverter current and the output voltage further comprises:

calculating a power factor according to the inverter current and the output voltage;

the process of turning off the high-frequency switch tube in the first half-bridge module comprises the following steps:

when the power factor is 1, turning off the first high-frequency switching tube in the first half-bridge module, and closing the pulse of the second high-frequency switching tube in the first half-bridge module;

and when the power factor is not 1, turning off the second high-frequency switching tube in the first half-bridge module, and closing the pulse of the first high-frequency switching tube in the first half-bridge module.

8. The shutdown method according to any one of claims 1 to 7, characterized in that the preset time period is in particular a switching tube dead time.

9. The shutdown system of the ANPC type three-level inverter is characterized in that the ANPC type three-level inverter comprises an upper half-bridge module and a lower half-bridge module, each half-bridge module comprises a low-frequency switching tube and two high-frequency switching tubes with complementary pulses, the two high-frequency switching tubes with complementary pulses comprise a first high-frequency switching tube and a second high-frequency switching tube, the first ends of the low-frequency switching tubes are connected with the first ends of the two high-frequency switching tubes, the second ends of the low-frequency switching tubes serve as the output ends of the ANPC type three-level inverter, the second ends of the first high-frequency switching tubes are connected with a bus anode or a bus cathode, and the second ends of the second high-frequency switching tubes are connected with a bus midpoint; the shutdown system comprises a sampling module, a timing module and an action module, wherein: the sampling module is used for sampling the inversion current and the output voltage of the ANPC type three-level inverter; the timing module is configured to:

when a shutdown signal is received, calculating the current zero crossing point moment according to the inverter current and the output voltage, and triggering the action module to turn off the high-frequency switching tube in the first half-bridge module;

waiting for a preset time period, and triggering the action module to turn on the second high-frequency switch tube in the second half-bridge module;

triggering the action module to turn off the low-frequency switching tube in the first half-bridge module at the moment of the current zero crossing point;

waiting for the preset time period, and triggering the action module to turn off the second high-frequency switch tube in the second half-bridge module;

wherein the first half-bridge module is: before the shutdown signal is received, the high-frequency switch tube works in the half-bridge module, and the second half-bridge module is the other half-bridge module.

10. A shutdown apparatus for an ANPC type three-level inverter, comprising:

a memory for storing a computer program;

processor for implementing the steps of a shut down method of an ANPC type three-level inverter according to any of the claims 1 to 8 when executing said computer program.

Technical Field

The invention relates to the field of inverter control, in particular to a shutdown method, a shutdown system and a shutdown device of an ANPC (adaptive neural network) type three-level inverter.

Background

Currently, an ANPC (Active Neutral-Point-Clamped) three-level inverter, as shown in fig. 1, has a greater advantage than an NPC (Neutral-Point-Clamped) three-level inverter, and thus is increasingly used in photovoltaic inverter applications in high-voltage and high-power situations.

The shutdown of the ANPC three-level inverter is divided into normal shutdown and fault shutdown, wherein the normal shutdown is to shut down T1/T4 after the inverter current is reduced to 0, and then shut down T2/T3/T5/T6 after waiting for a long enough time; and turning off the T1/T4 during emergency shutdown, and then waiting for a long enough time to turn off the T2/T3 and the T5/T6. The shutdown time sequence can realize reliable shutdown only under the ideal conditions of pure active power and small inductance ripple, phase change is very easy to occur when the current crosses zero in the actual condition, reverse current is generated, if shutdown is still performed according to the original method at the moment, when T1/T4 is shut down, T2/T3/T5/T6 is not shut down yet, the reverse current is further increased, so that T2/T3/T5/T6 bears large impact current, and T2/T3 is easily damaged due to overvoltage when T2/T3/T5/T6 is shut down.

Therefore, how to provide a solution to the above technical problems is a problem to be solved by those skilled in the art.

Disclosure of Invention

In view of the above, the present invention is directed to a shutdown method, system and apparatus for an ANPC type three-level inverter. The specific scheme is as follows:

a shutdown method of an ANPC type three-level inverter, wherein the ANPC type three-level inverter comprises an upper half-bridge module and a lower half-bridge module, each half-bridge module comprises a low-frequency switching tube and two pulse complementary high-frequency switching tubes, the two pulse complementary high-frequency switching tubes comprise a first high-frequency switching tube and a second high-frequency switching tube, the first ends of the low-frequency switching tubes and the first ends of the two high-frequency switching tubes are connected, the second end of the low-frequency switching tube serves as an output end of the ANPC type three-level inverter, the second end of the first high-frequency switching tube is connected with a bus anode or a bus cathode, and the second end of the second high-frequency switching tube is connected with a bus midpoint, the shutdown method comprises the following steps:

sampling the inversion current and the output voltage of the ANPC type three-level inverter;

when a shutdown signal is received, calculating the zero crossing point moment of current according to the inverter current and the output voltage, and shutting down the high-frequency switching tube in the first half-bridge module;

waiting for a preset time period, and turning on the second high-frequency switching tube in the second half-bridge module;

turning off the low-frequency switching tube in the first half-bridge module at the moment of the current zero crossing point;

waiting for the preset time period, and turning off the second high-frequency switching tube in the second half-bridge module;

wherein the first half-bridge module is: before the shutdown signal is received, the high-frequency switch tube works in the half-bridge module, and the second half-bridge module is the other half-bridge module.

Preferably, when the shutdown signal is a normal shutdown signal, the calculating a current zero-crossing point time according to the inverter current and the output voltage includes:

calculating a first delay time duration according to a first formula, the first formula comprising:

；

whereinFor the first delay time period,the load inductor is connected with the output end;the current change amount of the inverter current is from the moment when the high-frequency switch tube in the first half-bridge module is turned off to the current zero crossing point;is composed ofA voltage variation of the corresponding output voltage;

determining the current zero-crossing time as: and waiting for the time after the first delay time from the turning off of the high-frequency switch tube in the first half-bridge module.

Preferably, the process of turning off the high-frequency switching tube in the first half-bridge module includes:

judging whether the current inverter current is larger than a threshold value;

if not, the high-frequency switching tube in the first half-bridge module is directly turned off;

if so, controlling the first half-bridge module until the current inverter current is not greater than the threshold value, and then turning off the high-frequency switching tube in the first half-bridge module.

Preferably, when the shutdown signal is an emergency shutdown signal, the calculating a current zero-crossing point time according to the inverter current and the output voltage includes:

according to the inverter current and the output voltage, calculating the maximum current value of the inverter current after the action of turning off the high-frequency switching tube in the first half-bridge module;

calculating a second delay time length for the inverter current to be reduced from the maximum current value to zero;

determining the current zero-crossing time as: and waiting for the time after the second delay time length from the time when the inverter current reaches the maximum current value.

Preferably, the calculating, according to the inverter current and the output voltage, a maximum current value of the inverter current after the action of turning off the high-frequency switching tube in the first half-bridge module includes:

calculating the maximum current value of the inverter current after the action of turning off the high-frequency switching tube in the first half-bridge module according to a second formula, wherein the second formula comprises the following steps:

；

whereinFor the said maximum current value, the current value is,for the inverter current upon receipt of the shutdown signal,as in the DC offset curve equationA corresponding offset value;the voltage variation of the output voltage is the voltage variation from the time when the shutdown signal is received to the time when the inverter current reaches the maximum current value;the system is delayed.

Preferably, the calculating a second delay time duration for the inverter current to decrease from the maximum current value to zero includes:

calculating a second delay time duration for the inverter current to decrease from the maximum current value to zero according to a third formula, where the third formula includes:

；

wherein the content of the first and second substances,is the second delay time length;and outputting the voltage variation of the output voltage from the moment when the inverter current reaches the maximum current value to the current zero-crossing point.

Preferably, the method further includes, while calculating a current zero-crossing point time according to the inverter current and the output voltage:

calculating a power factor according to the inverter current and the output voltage;

the process of turning off the high-frequency switch tube in the first half-bridge module comprises the following steps:

when the power factor is 1, turning off the first high-frequency switching tube in the first half-bridge module, and closing the pulse of the second high-frequency switching tube in the first half-bridge module;

and when the power factor is not 1, turning off the second high-frequency switching tube in the first half-bridge module, and closing the pulse of the first high-frequency switching tube in the first half-bridge module.

Preferably, the preset time period is dead time of the switching tube.

Correspondingly, the application also discloses a shutdown system of the ANPC type three-level inverter, the ANPC type three-level inverter comprises an upper half-bridge module and a lower half-bridge module, each half-bridge module comprises a low-frequency switching tube and two high-frequency switching tubes complementary to pulses, the two high-frequency switching tubes complementary to pulses comprise a first high-frequency switching tube and a second high-frequency switching tube, the first end of the low-frequency switching tube is connected with the first ends of the two high-frequency switching tubes, the second end of the low-frequency switching tube serves as the output end of the ANPC type three-level inverter, the second end of the first high-frequency switching tube is connected with the positive pole or the negative pole of the bus, and the second end of the second high-frequency switching tube is connected with the midpoint of the bus; the shutdown system comprises a sampling module, a timing module and an action module, wherein: the sampling module is used for sampling the inversion current and the output voltage of the ANPC type three-level inverter; the timing module is configured to:

when a shutdown signal is received, calculating the current zero crossing point moment according to the inverter current and the output voltage, and triggering the action module to turn off the high-frequency switching tube in the first half-bridge module;

waiting for a preset time period, and triggering the action module to turn on the second high-frequency switch tube in the second half-bridge module;

triggering the action module to turn off the low-frequency switching tube in the first half-bridge module at the moment of the current zero crossing point;

waiting for the preset time period, and triggering the action module to turn off the second high-frequency switch tube in the second half-bridge module;

wherein the first half-bridge module is: before the shutdown signal is received, the high-frequency switch tube works in the half-bridge module, and the second half-bridge module is the other half-bridge module.

Correspondingly, this application has still disclosed the shutdown device of an ANPC type three-level inverter, includes:

a memory for storing a computer program;

a processor for implementing the steps of the shutdown method of the ANPC-type three-level inverter as described in any of the above when executing the computer program.

The application discloses a shutdown method of an ANPC type three-level inverter, which comprises the following steps: sampling the inversion current and the output voltage of the ANPC type three-level inverter; when a shutdown signal is received, calculating the zero crossing point moment of current according to the inverter current and the output voltage, and shutting down the high-frequency switching tube in the first half-bridge module; waiting for a preset time period, and turning on the second high-frequency switching tube in the second half-bridge module; turning off the low-frequency switching tube in the first half-bridge module at the moment of the current zero crossing point; waiting for the preset time period, and turning off the second high-frequency switching tube in the second half-bridge module; wherein the first half-bridge module is: before the shutdown signal is received, the high-frequency switch tube works in the half-bridge module, and the second half-bridge module is the other half-bridge module. When the shutdown signal is received, the zero crossing point time of the current is determined according to the inverter current and the output voltage, and the action time of all the switching tubes is specified, so that the phase change can not occur when the current crosses zero, the working of all the switching tubes in a safety range is ensured, and the inverter can be reliably shut down.

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 embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the provided drawings without creative efforts.

Fig. 1 is a circuit topology diagram of an ANPC type three-level inverter;

FIG. 2 is a flowchart illustrating steps of a shutdown method for an ANPC type three-level inverter according to an embodiment of the present invention;

FIG. 3 is a timing diagram illustrating the shutdown of an ANPC type three-level inverter according to an embodiment of the present invention;

FIG. 4 is a timing diagram illustrating the shutdown of an ANPC type three-level inverter according to an embodiment of the present invention;

FIG. 5 is a timing diagram illustrating the shutdown of an ANPC type three-level inverter according to an embodiment of the present invention;

fig. 6 is a structural distribution diagram of a shutdown system of an ANPC type three-level inverter according to an embodiment of the present invention.

Detailed Description

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

The traditional shutdown time sequence can realize reliable shutdown only under the ideal conditions of pure active power and small inductance ripple, phase change is easy to occur during current zero crossing under the actual condition, reverse current is generated, and if the shutdown is still performed according to the original method, a switch tube can bear larger impact current or is easy to damage due to overvoltage.

When the shutdown signal is received, the zero crossing point time of the current is determined according to the inverter current and the output voltage, and the action time of all the switching tubes is specified, so that the phase change can not occur when the current crosses zero, the working of all the switching tubes in a safety range is ensured, and the inverter can be reliably shut down.

The embodiment of the invention discloses a shutdown method of an ANPC type three-level inverter, the ANPC type three-level inverter comprises an upper half-bridge module and a lower half-bridge module, each half-bridge module comprises a low-frequency switching tube and two pulse complementary high-frequency switching tubes, the two pulse complementary high-frequency switching tubes comprise a first high-frequency switching tube and a second high-frequency switching tube, the first ends of the low-frequency switching tubes and the first ends of the two high-frequency switching tubes are connected, the second end of the low-frequency switching tubes is used as the output end of the ANPC type three-level inverter, the second end of the first high-frequency switching tube is connected with the positive pole or the negative pole of a bus, the second end of the second high-frequency switching tube is connected with the midpoint of the bus, referring to the circuit structure of the ANPC type three-level inverter shown in figure 1, wherein the first end of a capacitor C1 and the first end of a C2 are respectively the positive pole and the negative pole of the bus, the common point of C1 and the common point of the C2 is used as the midpoint of the bus, the low-frequency switch tube of the upper half-bridge module is T2, the first high-frequency switch tube is T1, the second high-frequency switch tube is T5, the low-frequency switch tube of the lower half-bridge module is T3, the first high-frequency switch tube is T4, the second high-frequency switch tube is T6, no matter the low-frequency switch tube or the low-frequency switch tube, the T1-T6 are provided with corresponding diodes D1-D6 to be matched with the low-frequency switch tube.

Referring to fig. 2, the shutdown method includes:

s1: sampling the inversion current and the output voltage of the ANPC type three-level inverter;

s2: when a shutdown signal is received, calculating the zero crossing point moment of current according to the inverter current and the output voltage, and turning off a high-frequency switching tube in the first half-bridge module;

s3: waiting for a preset time period, and turning on a second high-frequency switching tube in the second half-bridge module;

s4: turning off a low-frequency switching tube in the first half-bridge module at the moment of current zero crossing;

s5: waiting for a preset time period, and turning off a second high-frequency switching tube in the second half-bridge module;

wherein the first half-bridge module is: before a shutdown signal is received, the high-frequency switching tube is a working half-bridge module, and the second half-bridge module is the other half-bridge module.

That is, if the high-frequency switching tube T1 or T5 is working before receiving the shutdown signal, the first half-bridge module is the upper half-bridge module, and the second half-bridge module is the lower half-bridge module, and if the high-frequency switching tube T4 or T6 is working before receiving the shutdown signal, the first half-bridge module is the lower half-bridge module, and the second half-bridge module is the upper half-bridge module; in addition, the half-bridge module corresponding to the operating low-frequency switching tube may also be determined as the first half-bridge module, and only the functional description of the first half-bridge module as the operating half-bridge module is given here.

It can be understood that, the step S1 monitors the inverter current and the output voltage, when a shutdown signal is received, the step S2 operates the inverter current and the output current collected at the current time to determine a current zero crossing point time, and then turns off the high-frequency switching tube in the first half-bridge module, because pulses of the first high-frequency switching tube and the second high-frequency switching tube are complementary during actual operation, only one high-frequency switching tube is turned on at the same time, when the high-frequency switching tube is turned off, only the currently turned-on high-frequency switching tube is turned off, and the other high-frequency switching tube is itself turned on, so that subsequent pulse output of the high-frequency switching tube is stopped; receiving a shutdown signal and shutting down a time difference between high-frequency switching tubes in a first half-bridge module, determining according to actual conditions that the time difference is 0 when the shutdown signal is an emergency shutdown signal, and performing normal shutdown according to a normal shutdown delay requirement when the shutdown signal is a normal shutdown signal; then step S3 is carried out, a preset time period is waited, a second high-frequency switch tube in a second half-bridge module is switched on, and the effect of clamping voltage is achieved; step S4 is entered, the low-frequency switching tube in the first half-bridge module is turned off after waiting for the moment of current zero crossing, and the turn-off at the moment ensures that the phenomenon of voltage and current phase change caused by the fact that the current passes through the other side of the zero point on the switching tube in the prior art can not occur even if the inductance ripple exists and the non-pure active power exists; then, the process proceeds to step S5 to wait for a preset time period, and turn off the second high frequency switch tube in the second half-bridge module.

It can be understood that, the high frequency switch tubes operated in the second half-bridge module in steps S3 and S5 are both the second high frequency switch tubes for achieving the effect of clamping voltage, so that the action of turning on the high frequency switch tubes of the second half-bridge module should be followed by the action of turning off the high frequency switch tubes of the first half-bridge module, the smaller the time difference between the two actions is, the better the time difference is, but in order to protect the circuit and avoid the occurrence of false conduction, the time difference must not be smaller than the dead time of the mechanical action of the device, and therefore the preset time period is generally selected as the dead time of the switch tubes.

It should be noted that, when various actions are described above, the time corresponding to the action includes two times, namely, a time period and a time period, specifically:

at the moment T _01, turning off a high-frequency switching tube of the first half-bridge module;

waiting for a preset time td, namely at the time of T _01+ td, turning on a second high-frequency switch tube in the second half-bridge module;

at the time of T _02, namely the current zero crossing point time, the low-frequency switching tube in the first half-bridge module is turned off;

and waiting for a preset time period td, namely at the moment of T _02+ td, turning off a second high-frequency switching tube in the second half-bridge module.

It can be understood that, the high-frequency switching tubes in the first half-bridge module operating at different power factors are different, and therefore, the turning-off of the high-frequency switching tubes is implemented by both turning-off the switching tubes in the conducting state and pulse-blocking the switching tubes in the turning-off state, in order that all the high-frequency switching tubes in the first half-bridge module are not turned on after step S1, specifically, while calculating the current zero-crossing time according to the inverter current and the output voltage in step S2, the method further includes:

calculating a power factor according to the inversion current and the output voltage;

therefore, the process of turning off the high-frequency switch tube in the first half-bridge module comprises the following steps:

when the power factor is 1, a first high-frequency switch tube in the first half-bridge module is turned off, and the pulse of a second high-frequency switch tube in the first half-bridge module is closed;

and when the power factor is not 1, turning off the second high-frequency switching tube in the first half-bridge module, and closing the pulse of the first high-frequency switching tube in the first half-bridge module.

Specifically, taking the upper half-bridge module as an example of the first half-bridge module, before receiving the shutdown signal, the T1 or T5 of the upper half-bridge module is working, the T2 is in a constant on state, the second high-frequency switch tube in the second half-bridge module is T6, and the specific shutdown timing sequence is as shown in table 1 below:

TABLE 1 Universal shutdown sequence when the first half-bridge module is the top half-bridge module

When the lower half-bridge module is used as the first half-bridge module, the switching tubes thereof correspond to the above case, that is, the first high-frequency switching tube T1 corresponds to T4, the second high-frequency switching tube T5 corresponds to T6, and the low-frequency switching tube T2 corresponds to T3, and the implementation can be performed according to the same processing concept.

It can be understood that, considering the time delay of the system in the circuit, except that the electrical value collection of step S1 involves the feedback of the actual electrical state, all the switch tube actions of steps S2-S5 are clocked by independent clocks according to the action timing sequence set in table 1.

The application discloses a shutdown method of an ANPC type three-level inverter, which comprises the following steps: sampling the inversion current and the output voltage of the ANPC type three-level inverter; when a shutdown signal is received, calculating the zero crossing point moment of current according to the inverter current and the output voltage, and turning off a high-frequency switching tube in the first half-bridge module; waiting for a preset time period, and turning on a second high-frequency switching tube in the second half-bridge module; turning off a low-frequency switching tube in the first half-bridge module at the moment of current zero crossing; waiting for a preset time period, and turning off a second high-frequency switching tube in the second half-bridge module; wherein the first half-bridge module is: before a shutdown signal is received, the high-frequency switching tube is a working half-bridge module, and the second half-bridge module is the other half-bridge module. When the shutdown signal is received, the zero crossing point time of the current is determined according to the inverter current and the output voltage, and the action time of all the switching tubes is specified, so that the phase change can not occur when the current crosses zero, the working of all the switching tubes in a safety range is ensured, and the inverter can be reliably shut down.

The embodiment of the invention discloses a specific shutdown method of an ANPC type three-level inverter, and compared with the previous embodiment, the embodiment further explains and optimizes the technical scheme. Specifically, when the shutdown signal is a normal shutdown signal, the process of calculating the zero crossing point time of the current according to the inverter current and the output voltage includes:

calculating a first delay time duration according to a first formula, the first formula comprising:

；

whereinFor the first delay time period,the load inductor is connected with the output end;the current change amount of the inverter current is from the moment when the high-frequency switch tube in the first half-bridge module is turned off to the current zero crossing point;is composed ofA voltage variation of the corresponding output voltage;

determining the current zero-crossing time as follows: and waiting for the time after the first delay time from the turning off of the high-frequency switch tube in the first half-bridge module.

It can be understood that the output voltage, the load inductance and the inverter current have a corresponding relationship, and may be used to calculate the output voltage that does not occur, and further determine the voltage variation related thereto, which belongs to the common general knowledge and is not described herein again.

Further, in the normal turn-off process, when considering that the inverter current does not exceed the threshold, the process of turning off the high-frequency switch tube in the first half-bridge module includes:

judging whether the current inversion current is larger than a threshold value;

if not, directly turning off a high-frequency switch tube in the first half-bridge module;

and if so, controlling the first half-bridge module until the current inverter current is not greater than the threshold value, and then turning off a high-frequency switching tube in the first half-bridge module.

It can be understood that if the current inverter current is not greater than the threshold when the shutdown signal is received, the high-frequency switching tube of the first half-bridge module is directly turned off, and the current variation is the difference between the current inverter current and the zero current.

It should be noted that, in this embodiment, the time in the turn-off sequence is further limited, so that the above half-bridge module is taken as the first half-bridge module as an example, the time for turning off the high-frequency switch tube of the first half-bridge module is taken as T _11, and the whole switching sequence is shown in table 2 below.

TABLE 2 shutdown sequence when the upper half-bridge module is the first half-bridge module and receives a normal shutdown signal

Further, taking the case of pure active power and a power factor of 1 as an example, a shutdown timing chart of the current inverter current not greater than the threshold is shown in fig. 3, a shutdown timing chart of the current inverter current greater than the threshold is shown in fig. 4, and finally all switching tubes are turned off to complete reliable shutdown.

The embodiment of the invention discloses a specific shutdown method of an ANPC type three-level inverter, and compared with the previous embodiment, the embodiment further explains and optimizes the technical scheme. Specifically, when the shutdown signal is an emergency shutdown signal, the high-frequency switching tube in the first half-bridge module is turned off immediately, and meanwhile, calculating the current zero-crossing point moment according to the inverter current and the output voltage includes:

calculating the maximum current value of the inverter current after the action of switching off a high-frequency switching tube in the first half-bridge module according to the inverter current and the output voltage;

calculating a second delay time length for reducing the inverter current from the maximum current value to zero;

determining the current zero-crossing time as follows: and waiting for the time after the second delay time from the time when the inverse current reaches the maximum current value.

Further, according to the inverter current and the output voltage, a process of calculating a maximum current value of the inverter current after an action of turning off a high-frequency switching tube in the first half-bridge module includes:

calculating the maximum current value of the inverter current after the action of turning off the high-frequency switching tube in the first half-bridge module according to a second formula, wherein the second formula comprises the following steps:

；

whereinFor the said maximum current value, the current value is,for the inverter current upon receipt of the shutdown signal,as in the DC offset curve equationA corresponding offset value;the voltage variation of the output voltage is the voltage variation from the time when the shutdown signal is received to the time when the inverter current reaches the maximum current value;the system is delayed.

The system delay comprises sampling delay, control delay and response delay, and the three delays are known delays which are determined by hardware and cannot be eliminated; the dc offset curve equation is known and is typically provided by the equipment manufacturer.

It can be understood that after the high-frequency switch tube of the first half-bridge module is turned off, the inverter current will reach the maximum current value after the system delay.

Further, the process of calculating the second delay time duration for the inverter current to decrease from the maximum current value to zero includes:

calculating a second delay time period for the inverter current to decrease from the maximum current value to zero according to a third formula, wherein the third formula comprises:

；

wherein the content of the first and second substances,is the second delay time length;and outputting the voltage variation of the voltage from the time when the inverter current reaches the maximum current value to the time when the current crosses zero.

It can be understood that the output voltage, the load inductance and the inverter current have a corresponding relationship, and may be used to calculate the output voltage that does not occur, and further determine the voltage variation related thereto, which belongs to the common general knowledge and is not described herein again.

It should be noted that, in this embodiment, the time in the turn-off sequence is further limited, so that the above half-bridge module is taken as the first half-bridge module as an example, the time when the high-frequency switching tube of the first half-bridge module is turned off immediately after receiving the emergency shutdown signal is taken as T _21, and the whole switching sequence is shown in table 3 below.

TABLE 3 shutdown sequence when the upper half-bridge module is the first half-bridge module and receives the emergency shutdown signal

Further, taking the case of pure active power and power factor of 1 as an example, the timing diagram of shutdown after receiving the emergency shutdown signal is shown in fig. 5, and finally all switching tubes are turned off to complete reliable shutdown.

Correspondingly, the application also discloses a shutdown system of the ANPC type three-level inverter, the ANPC type three-level inverter comprises an upper half-bridge module and a lower half-bridge module, each half-bridge module comprises a low-frequency switching tube and two high-frequency switching tubes complementary to pulses, the two high-frequency switching tubes complementary to pulses comprise a first high-frequency switching tube and a second high-frequency switching tube, the first end of the low-frequency switching tube is connected with the first ends of the two high-frequency switching tubes, the second end of the low-frequency switching tube serves as the output end of the ANPC type three-level inverter, the second end of the first high-frequency switching tube is connected with the positive pole or the negative pole of the bus, and the second end of the second high-frequency switching tube is connected with the midpoint of the bus;

as shown in fig. 6, the shutdown system includes a sampling module 1, a timing module 2, and an action module 3, where: the sampling module 1 is used for sampling the inversion current and the output voltage of the ANPC type three-level inverter; the timing module 2 is configured to:

when a shutdown signal is received, calculating the current zero crossing point moment according to the inverter current and the output voltage, and triggering the action module 3 to turn off the high-frequency switching tube in the first half-bridge module;

waiting for a preset time period, triggering the action module 3 to turn on the second high-frequency switch tube in the second half-bridge module;

triggering the action module 3 to turn off the low-frequency switching tube in the first half-bridge module at the moment of the current zero crossing point;

waiting for the preset time period, triggering the action module 3 to turn off the second high-frequency switch tube in the second half-bridge module;

wherein the first half-bridge module is: before the shutdown signal is received, the high-frequency switch tube works in the half-bridge module, and the second half-bridge module is the other half-bridge module.

When a shutdown signal is received, the zero crossing point time of the current is determined according to the inverter current and the output voltage, and the action time of all the switching tubes is specified, so that the phase change can not occur when the current crosses zero, the working of all the switching tubes in a safety range is ensured, and the inverter can be reliably shut down.

In some specific embodiments, when the shutdown signal is a normal shutdown signal, the process of the timing module 2 calculating a current zero-crossing time according to the inverter current and the output voltage includes:

calculating a first delay time duration according to a first formula, the first formula comprising:

；

whereinFor the first delay time period,the load inductor is connected with the output end;the current change amount of the inverter current is from the moment when the high-frequency switch tube in the first half-bridge module is turned off to the current zero crossing point;is composed ofA voltage variation of the corresponding output voltage;

determining the current zero-crossing time as: and waiting for the time after the first delay time from the turning off of the high-frequency switch tube in the first half-bridge module.

In some specific embodiments, the process of the action module 3 turning off the high-frequency switch tube in the first half-bridge module includes:

judging whether the current inverter current is larger than a threshold value;

if not, the high-frequency switching tube in the first half-bridge module is directly turned off;

if so, controlling the first half-bridge module until the current inverter current is not greater than the threshold value, and then turning off the high-frequency switching tube in the first half-bridge module.

In some specific embodiments, when the shutdown signal is an emergency shutdown signal, the calculating, by the timing module 2, a current zero-crossing time according to the inverter current and the output voltage includes:

according to the inverter current and the output voltage, calculating the maximum current value of the inverter current after the action of turning off the high-frequency switching tube in the first half-bridge module;

calculating a second delay time length for the inverter current to be reduced from the maximum current value to zero;

determining the current zero-crossing time as: and waiting for the time after the second delay time length from the time when the inverter current reaches the maximum current value.

In some specific embodiments, the process of calculating, by the timing module 2, a maximum current value of the inverter current after the action of turning off the high-frequency switching tube in the first half-bridge module according to the inverter current and the output voltage includes:

calculating the maximum current value of the inverter current after the action of turning off the high-frequency switching tube in the first half-bridge module according to a second formula, wherein the second formula comprises the following steps:

；

whereinFor the said maximum current value, the current value is,for the inverter current upon receipt of the shutdown signal,as in the DC offset curve equationA corresponding offset value;the voltage variation of the output voltage is the voltage variation from the time when the shutdown signal is received to the time when the inverter current reaches the maximum current value;the system is delayed.

In some specific embodiments, the process of calculating, by the calculation module 2, the second delay time duration for decreasing the inverter current from the maximum current value to zero includes:

calculating a second delay time period for the inverter current to decrease from the maximum current value to zero according to a third formula,

the third formula includes:

；

wherein the content of the first and second substances,is the second delay time length;and outputting the voltage variation of the output voltage from the moment when the inverter current reaches the maximum current value to the current zero-crossing point.

In some specific embodiments, the timing module 2, while calculating the current zero-crossing time according to the inverter current and the output voltage, further includes:

calculating a power factor according to the inverter current and the output voltage;

when the power factor is 1, determining the high-frequency switch tube which is switched on and off in the second half-bridge module as the second high-frequency switch tube in the second half-bridge module;

when the power factor is smaller than 1, the high-frequency switch tube which is switched on and off in the second half-bridge module is determined to be the first high-frequency switch tube in the second half-bridge module.

In some specific embodiments, the preset time period is specifically a switch tube dead time.

Correspondingly, the embodiment of the present application further discloses a shutdown device of an ANPC type three-level inverter, including:

a memory for storing a computer program;

a processor for implementing the steps of the shutdown method of the ANPC-type three-level inverter as described in any of the above when executing the computer program.

For details of the shutdown method of the ANPC type three-level inverter, reference may be made to the related description in the foregoing embodiments, and details are not described herein again.

The shutdown device of the ANPC type three-level inverter in the present embodiment has the same technical effects as the shutdown method of the ANPC type three-level inverter in the foregoing embodiments.

Finally, it should also be 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.

The shutdown method, system and apparatus of the ANPC type three-level inverter provided by the present invention are described in detail above, and a specific example is applied in the present document to explain the principle and the implementation of the present invention, and the description of the above embodiment is only used to help understanding the method and the core idea of the present invention; meanwhile, for a person skilled in the art, according to the idea of the present invention, there may be variations in the specific embodiments and the application scope, and in summary, the content of the present specification should not be construed as a limitation to the present invention.