CN103869208A - Open-circuit fault detection method for three-phase inverter with phase-redundant fault-tolerant structure - Google Patents

Abstract

The invention discloses an open-circuit fault detection method for a three-phase inverter with a phase-redundant fault-tolerant structure. The method comprises the following steps: normalizing a three-phase expected voltage to obtain a detection variable (dn) of the three-phase expected voltage; calculating to obtain a detection variable (an) according to an average value of an absolute value of the three-phase expected voltage; judging to obtain fault indications (Dn and An) through threshold values (km and kd) of the detection variable (dn) and the detection variable (an); searching and locating a switch tube having an open-circuit fault in a fault location table I according to the fault indications (Dn and An). Faults with three possibilities in the fault location table I can be further located by using a method of replacing a bridge arm, on which the switch tube determined to have the open-circuit fault is positioned, with a redundant fourth bridge arm. The method is applied to open-circuit fault detection of the three-phase inverter in a driving control system of an electric vehicle, at most 27 open-circuit faults can be detected, and an accurate basis is provided for fault-tolerant control and fault processing of the system.

Description

The three-phase inverter open fault detection method of phase redundancy fault-tolerant architecture

Technical field

The invention belongs to three-phase inverter fault detection technique field, more specifically say, relate to a kind of three-phase inverter open fault detection method of phase redundancy fault-tolerant architecture.

Background technology

In recent years, the motor driven systems of being powered by voltage source inverter has obtained extensive application on electric automobile, but inverter wherein but very easily breaks down.In order to improve the safety and reliability of electric automobile, need to carry out effectively detecting in real time to the fault of inverter, locate and isolation, and take fault-tolerant control.

In order not reduce system performance, at present the most widely used is to adopt phase redundancy fault-tolerant architecture at three-phase inverter.Fig. 1 is the three-phase inverter schematic diagram of phase redundancy fault-tolerant architecture.As shown in Figure 1, in the three-phase inverter of phase redundancy fault-tolerant architecture, six switching tube composition three-phase inverters of T1～T6, the 4th brachium pontis 11 of T7, T8 composition redundancy, for three bidirectional thyristors 12 of isolated fault phase, be used for switching three bidirectional thyristors 13 of the 4th brachium pontis.When three-phase inverter is normally worked, the 4th brachium pontis do not participate in work; While breaking down, take over fault phase with the 4th brachium pontis 11 and work on.Fig. 2 is the system chart of the motor drive controller based on phase redundancy fault-tolerant architecture.As shown in Figure 2, motor drive controller based on phase redundancy fault-tolerant architecture comprises, vector control module 21, SVPWM(Space Vector Pulse Width Modulation, space vector pulse width modulation) modulation module 22, phase redundancy Fault tolerant inverter 23, motor 24, speed pickup 25, current sensor 26 and open fault detection module 27.

The prerequisite that realizes fault-tolerant control is that fault of converter is detected.At present; carry out a large amount of substance work for inverter switching device tube short circuit fault; and the open fault of switching tube does not obtain due attention; because open fault can't cause system to be shut down after occurring at once; but it may cause the secondary failure of other inverter assemblies, finally bring the maintenance cost of great number to system.

For the open fault of inverter switching device pipe, one of at present main research direction is the fault detection method based on voltage.Fig. 3 is the inverter switching device tube open circuit fault detection method schematic diagram based on voltage.As shown in Figure 3, the inverter switching device tube open circuit fault detection method based on voltage comprises the following steps:

(1) by the reference voltage u under two-phase rest frame _α, u _β(conventionally expect rotating speed by motor

theoretical conversion obtains) through Clark, coordinate transform is converted into three-phase reference voltage u _a, u _b, u _c, by the expectation voltage under two-phase rest frame

(expect rotating speed by vector control module according to motor

motor actual speed

motor three-phase current obtains) through Clark, coordinate transform is converted into three-phase expectation voltage

$u_c^{*}:$

$\left[\begin{array}{c}{u}_a\\ u_b\\ u_c\end{array}\right]=\sqrt{\frac{2}{3}}\left[\begin{array}{cc}1& 0\\ -\frac{1}{2}& \frac{\sqrt{3}}{2}\\ -\frac{1}{2}& -\frac{\sqrt{3}}{2}\end{array}\right]\left[\begin{array}{c}{u}_{\mathrm{\α}}\\ u_{\mathrm{\β}}\end{array}\right],\left[\begin{array}{c}{u}_a^{*}\\ u_b^{*}\\ u_c^{*}\end{array}\right]=\sqrt{\frac{2}{3}}\left[\begin{array}{cc}1& 0\\ -\frac{1}{2}& \frac{\sqrt{3}}{2}\\ -\frac{1}{2}& -\sqrt{\frac{3}{2}}\end{array}\right]\left[\begin{array}{c}{u}_{\mathrm{\α}}^{*}\\ u_{\mathrm{\β}}^{*}\end{array}\right]$

(2) calculate open fault detection variable d _n:

First calculate three-phase reference voltage and three-phase and expect the poor of voltage:

$e_n=u_n-u_n^{*}$

Wherein, n ∈ { a, b, c};

The impact bringing in order to get rid of load variations, adopts DC bus-bar voltage to be normalized, and finally averages and obtains detection variable:

$d_n=<\frac{e_n}{V_{\mathrm{DC}}}>$

Under normal circumstances, < e in one-period _n> ≈ 0, so d _n≈ 0.In the time of fault of converter, the motor three-phase electricity of output fails to be convened for lack of a quorum and changes, thereby causes three-phase reference voltage and three-phase to expect the poor e of voltage _nchange, make the detection variable d in one-period _nchange, therefore can pass through detection variable d _nvalue carry out failure judgement.

(3) judge and locate concrete open fault:

Table 1 is fault of converter judgement table.Wherein, k _dfor predetermined threshold value.

Open fault switching tube	d a	d b	d c
				T1	＞k d	?	?
T2	＜-k d	?	?
				T3	?	＞k d	?
T4	?	＜-k d	?
				T5	?	?	＞k d
T6	?	?	＜-k d

But there is following shortcoming in the fault detection method based on voltage:

(1) can only detect and locate the open fault of single switching transistor, and it is just helpless that open fault is occurred multiple switching tubes to simultaneously;

(2) the reference voltage u under needed two-phase rest frame _α, u _βin general control system, need independent calculating, therefore will increase calculated amount;

(3) detect in order to eliminate load variations the impact bringing to open fault, the method adopts DC bus-bar voltage to be normalized, and this just needs busbar voltage Acquisition Circuit, concerning part control system, has increased cost.

Summary of the invention

The object of the invention is to overcome the deficiencies in the prior art, a kind of three-phase inverter open fault detection method of phase redundancy fault-tolerant architecture is provided, can realize 27 kinds of open faults and detect, for fault-tolerant control and the fault handling of system provide accurate foundation.

For achieving the above object, the three-phase inverter open fault detection method of phase redundancy fault-tolerant architecture of the present invention, comprises the following steps:

S1: obtain expectation voltage from motor driven systems closed-loop control system

then will through Clark, coordinate transform is converted into three-phase expectation voltage

S2: calculate detection variable d _n:

$d_n=\frac{<u_n^{*}>}{<\left|u_n^{*}\right|>}$

Wherein,

that three-phase is expected voltage

mean value,

it is three-phase voltage

the mean value of absolute value;

S3: calculate detection variable a _n:

$a_a=\frac{2<\left|u_a^{*}\right|>}{<\left|u_b^{*}\right|>+<\left|u_c^{*}\right|>}$

$a_b=\frac{2<\left|u_b^{*}\right|>}{<\left|u_a^{*}\right|>+<\left|u_c^{*}\right|>}$

$a_c=\frac{2<\left|u_c^{*}\right|>}{<\left|u_a^{*}\right|>+<\left|u_b^{*}\right|>}$

S4: set detection variable d _nwith detection variable a _nthreshold value k _mand k _d, judgement obtains indicating fault D _nand A _n:

$D_n=\left\{\begin{array}{cc}N& d_n\&le;-{\mathrm{<figure-callout\; id="0"\; label="k\; m"\; filenames="HDA0000473953210000031.png,HDA0000473953210000032.png"\; state="\{\{state\}\}">k</figure-callout>}}_m\\ 0& \left|d_n\right|<k_m\\ P& d_n\&GreaterEqual;k_m\end{array}\right.$

$A_n=\left\{\begin{array}{cc}H& a_n>k_d\\ L& a_n\&le;k_d\end{array}\right.$

S5: according to the indicating fault D obtaining _nand A _nthe switching tube of Search and Orientation generation open fault in localization of fault table one.

Further, in localization of fault table one, exist the fault of three kinds of likelihood of failure to adopt following methods to carry out further localization of fault:

The brachium pontis of determining the switching tube place that open fault occurs is substituted with the 4th brachium pontis of redundancy, again obtain and expect that voltage calculates indicating fault D ' _n, according to the switching tube of the localization of fault table two Search and Orientation generation open fault that comprises 12 kinds of open faults.

The three-phase inverter open fault detection method of phase redundancy fault-tolerant architecture of the present invention, first adopts three-phase to expect that voltage is normalized the detection variable d that obtains three-phase expectation voltage _n, and expect that according to three-phase the mean value calculation of the absolute value of voltage obtains detection variable a _n, by detection variable d _nwith detection variable a _nthreshold value k _mand k _djudgement obtains indicating fault D _nand A _n, according to indicating fault D _nand A _nthe switching tube of Search and Orientation generation open fault in localization of fault table one.For the fault that has three kinds of likelihood of failure in localization of fault table one, can further carry out localization of fault by the brachium pontis of determining the switching tube place that open fault occurs is carried out to alternative method with the 4th brachium pontis of redundancy.

The present invention has following beneficial effect:

(1) can orient 27 kinds of open faults, for fault-tolerant control or the fault handling of system provide foundation more accurately;

(2) input quantity using in the present invention can directly obtain from driving control system for electric machine, does not therefore need to increase extra sensor or other hardware circuits;

(3) algorithm is simple, overall calculation amount is little;

(4) by the reasonable setting of detection variable threshold value, can tolerate the detection variable fluctuation that motor speed changes or load variations causes, avoid fault misdescription.

Accompanying drawing explanation

Fig. 1 is the three-phase inverter schematic diagram of phase redundancy fault-tolerant architecture;

Fig. 2 is the system chart of the motor drive controller based on phase redundancy fault-tolerant architecture;

Fig. 3 is the inverter switching device tube open circuit fault detection method schematic diagram based on voltage;

Fig. 4 is the three-phase inverter open fault detection method schematic diagram of phase redundancy fault-tolerant architecture of the present invention;

Fig. 5 is motor three-phase current, the detection variable d of example 1 _nand a _noscillogram;

Fig. 6 is motor three-phase current, the detection variable d of example 2 _nand a _noscillogram;

Fig. 7 is motor three-phase current, detection variable d in motor speed change procedure _nand a _noscillogram;

Fig. 8 is motor three-phase current, detection variable d in load variations process _nand a _noscillogram.

Embodiment

Below in conjunction with accompanying drawing, the specific embodiment of the present invention is described, so that those skilled in the art understands the present invention better.Requiring particular attention is that, in the following description, in the time that perhaps the detailed description of known function and design can desalinate main contents of the present invention, these are described in here and will be left in the basket.

Embodiment

Fig. 4 is the three-phase inverter open fault detection method schematic diagram of phase redundancy fault-tolerant architecture of the present invention.As shown in Figure 4, the three-phase inverter open fault detection method of phase redundancy fault-tolerant architecture of the present invention comprises the following steps:

S1: obtain expectation voltage from motor driven systems closed-loop control system

then will through Clark, coordinate transform is converted into three-phase expectation voltage

S2: calculate detection variable dn.Unlike the prior art, in the present invention, directly adopt three-phase to expect voltage

the mean value of absolute value

be normalized, thereby eliminate the impact that load variations is brought, computing method are:

$d_n=\frac{<u_n^{*}>}{<\left|u_n^{*}\right|>}$

Wherein,

that three-phase is expected voltage

mean value,

it is three-phase voltage

the mean value of absolute value, computing formula is:

$<u_n^{*}>=\frac{\mathrm{<figure-callout\; id="2"\; label="w"\; filenames="HDA0000473953210000031.png,HDA0000473953210000032.png"\; state="\{\{state\}\}">w</figure-callout>}}{2\mathrm{\&pi;}}\underset{0}{\overset{\frac{2\mathrm{\&pi;}}{w}}{\&Integral;}}{u}_n^{*}\mathrm{dt}$

$<\left|u_n^{*}\right|>=\frac{\mathrm{<figure-callout\; id="2"\; label="w"\; filenames="HDA0000473953210000031.png,HDA0000473953210000032.png"\; state="\{\{state\}\}">w</figure-callout>}}{2\mathrm{\&pi;}}\underset{0}{\overset{\frac{2\mathrm{\&pi;}}{w}}{\&Integral;}}\left|u_n^{*}\right|\mathrm{dt}$

Wherein, w represents the stator current angular frequency of motor.

S3: in order to detect multiple switching tubes open fault simultaneously, the present invention has also increased a new detection variable a _n:

$a_a=\frac{2<\left|u_a^{*}\right|>}{<\left|u_b^{*}\right|>+<\left|u_c^{*}\right|>}$

$a_b=\frac{2<\left|u_b^{*}\right|>}{<\left|u_a^{*}\right|>+<\left|u_c^{*}\right|>}$

$a_c=\frac{2<\left|u_c^{*}\right|>}{<\left|u_a^{*}\right|>+<\left|u_b^{*}\right|>}$

Under normal circumstances, in one-period

so d _n≈ 0, a _n≈ 1.

S4: set detection variable d _nwith detection variable a _nthreshold value k _mand k _d, judgement obtains indicating fault D _nand A _n:

$D_n=\left\{\begin{array}{cc}N& d_n\&le;-{\mathrm{<figure-callout\; id="0"\; label="k\; m"\; filenames="HDA0000473953210000031.png,HDA0000473953210000032.png"\; state="\{\{state\}\}">k</figure-callout>}}_m\\ 0& \left|d_n\right|<k_m\\ P& d_n\&GreaterEqual;k_m\end{array}\right.$

$A_n=\left\{\begin{array}{cc}H& a_n>k_d\\ L& a_n\&le;k_d\end{array}\right.$

In motor actual moving process, because motor speed changes or load variations, can make detection variable d _nwith detection variable a _nproduce certain fluctuation, therefore threshold value k _mand k _darrange need can tolerate normal fluctuation.

S5: according to the indicating fault D obtaining _nand A _nthe switching tube of Search and Orientation generation open fault in localization of fault table one.Table 2 is fault navigation watch one.

Table 2

Wherein, [Tx] represents that open fault may occur switch transistor T x, also may be normal; (Tx/Ty) represent to have at least one open fault occurs in switch transistor T x and Ty, x, y represent switching tube sequence number, and "-" represents that this indicating fault can be arbitrary value, and no matter why this indicating fault is worth, and does not affect the judgement of this fault.

Can find out from localization of fault table one, now according to indicating fault D _nand A _ncan orient 21 kinds of open faults, even if there are some cannot completely specified fault, but interpretable open fault quantity be far away more than prior art.And the phase redundancy fault-tolerant architecture that the present invention can also adopt three-phase inversion to become device further the fault (fault 10 is to fault 15) that has three kinds of likelihood of failure carries out to localization of fault, utilize the 4th brachium pontis of redundancy to substitute the fault phase that open fault occurs, again locate fault according to indicating fault.Concrete grammar is:

The brachium pontis of determining the switching tube place that open fault occurs is substituted with the 4th brachium pontis of redundancy, again obtain and expect that voltage calculates indicating fault D ' _n.With the fault 10:T1 in localization of fault table one, T4 and T1, T5 & [T4] is example, for these two kinds of possible failure conditions, can affirm that open fault occurs switch transistor T 1.Therefore use the 4th brachium pontis to replace the brachium pontis (being T1 and T2) at T1 place to be reconstructed three-phase inverter, after reconstruct, can determine that T1 and T2 after replacing it are normal, so just can Resurvey data obtain indicating fault, judge that according to localization of fault table two open fault occurs T4, T5 open fault or T4 and T5 occurs open fault occurs simultaneously.Because the switching tube quantity that open fault occurs in three-phase inverter now reduces, only need to adopt an indicating fault D ' _ncan judge fault, therefore localization of fault table two is simplified greatly than localization of fault table one.Table 3 is fault navigation watch two.

Fault sequence number	The switching tube of open fault	D′ a	D′ b	D′ c
					1	T1	P		0	0
2	T2	N		0							0
					3	T3	0	P	0
4	T4	0	N	0
					5	T5	0	0	P
6	T6	0	0	N
					7	T1,T4	P	N	—
8	T2,T3	N	P	—
					9	T1,T6	P	—	N
10	T2,T5	N	—	P
					11	T3,T6	—	P	N
12	T4,T5	—	N	P

Table 3

Visible, the fault phase that open fault occurs by utilizing the 4th brachium pontis of redundancy to substitute re-starts localization of fault, can further locate the fault 10 in localization of fault table one to fault 16, thereby realize the location that amounts to 27 kinds of open faults.

With several instantiations, localization of fault validity of the present invention is described below.

Example 1:

Ac three-phase asynchronous motor rated power 1.1kW, rated speed 1390rpm, nominal torque 7.6Nm, rated current 2.89A, the nominal load that load torque is 50%.Detection variable threshold value k is set _m=0.08, k _d=0.93.Fig. 5 is motor three-phase current, the detection variable d of example 1 _nand a _noscillogram.As shown in Figure 5, three-phase inverter is set in this example 1 and occurs 3 faults: when time t=1.6s, open fault occurs T2; When t=1.8s, there is open fault in T1 and T2 simultaneously; When t=2s, there is open fault in T1, T2 and T4 simultaneously.

A) t=1.4～1.6s, as shown in Figure 5, motor three-phase current is symmetrical sine wave, d _n≈ 0, a _n≈ 1, inverter is normally worked, indicating fault D _a=D _b=D _c=0, A _a=A _b=A _c=H, does not have switching tube generation open fault as seen according to localization of fault table one, and three-phase inverter is working properly;

B) t=1.6～1.8s, as shown in Figure 5, there is negative half-wave in phase current Ia, in the time of t=1.641s, detection variable d _a≤-0.08, | d _b| < 0.08, | d _c| < 0.08, a _a> 0.93, a _b> 0.93, a _c> 0.93; Can obtain indicating fault D _a=N, D _b=0, D _c=0, A _a=A _b=A _c=H, according to localization of fault table one, orients switch transistor T 2 open fault occurs;

C) t=1.8～2s, as shown in Figure 5, phase current Ia is close to zero, in the time of t=1.828s, detection variable | d _a| < 0.08, | d _b| < 0.08, | d _c| < 0.08, a _a> 0.93, a _b≤ 0.93, a _c> 0.93; Can obtain indicating fault D _a=D _b=D _c=0, A _a=H, A _b=L, A _c=H.According to localization of fault table one, orient switch transistor T 1 and T2 open fault occurs simultaneously;

D) t=2～2.2s, as shown in Figure 5, phase current Ia close to zero, Ib occurs that negative half-wave appears in positive half-wave, Ic, in the time of t=2.041s, detection variable | d _a| < 0.08, d _b≤-0.08, d _c>=0.08, a _a> 0.93, a _b≤ 0.93, a _c> 0.93; So D _a=0, D _b=N, D _c=P, A _a=H, A _b=L, A _c=H.According to localization of fault table one, can orient switch transistor T 1, T2, and in T4 and T5 there is open fault at least one simultaneously.

Example 2:

Ac three-phase asynchronous motor rated power 1.1kW, rated speed 1390rpm, nominal torque 7.6Nm, rated current 2.89A, the nominal load that load torque is 50%.Detection variable threshold value k is set _m=0.08, k _d=0.93.Fig. 6 is motor three-phase current, the detection variable d of example 2 _nand a _noscillogram.As shown in Figure 6, three-phase inverter is set in this example 1 and occurs 3 faults: when t=1.6s, open fault occurs T1; When t=1.8s, there is open fault in T1 and T4 simultaneously; When t=2s, there is open fault in T1, T4 and T5 simultaneously.

E) t=1.4～1.6s, as shown in Figure 6, motor three-phase current is symmetrical sine wave, d _n≈ 0, a _n≈ 1, indicating fault D _a=D _b=D _c=0, A _a=A _b=A _c=H, does not have switching tube generation open fault as seen according to localization of fault table one, and three-phase inverter is working properly;

F) t=1.6～1.8s, as shown in Figure 6, there is negative half-wave in phase current Ia, in the time of t=1.649s, detection variable d _a>=0.08, | d _b| < 0.08, | d _c| < 0.08, a _a> 0.93, a _b> 0.93, a _c> 0.93; So indicating fault D _a=P, D _b=0, D _c=0, A _a=A _b=A _c=H, according to localization of fault table one, orients switch transistor T 1 open fault occurs;

G) t=1.8～2s, as shown in Figure 6, phase current Ia occurs that positive half-wave appears in negative half-wave, Ib, in the time of t=1.827s, detection variable d _a>=0.08, d _b≤-0.08, | d _c| < 0.08, a _a> 0.93, a _b> 0.93, a _c> 0.93; So indicating fault D _a=P, D _b=N, D _c=0, A _a=A _b=A _c=H.According to localization of fault table one, may be T1, T4 or T1, T5 or T1, T4, there is open fault in T5 simultaneously.At this moment, confirmable is that fault has occurred switch transistor T 1 certainly, utilizes the 4th brachium pontis to replace the brachium pontis at T1 place, and then reconstruct inverter detects again.Now, only have phase current Ib to occur positive half-wave, detection variable | d _a| < 0.08, d _b≤-0.08, | d _c| < 0.08, indicating fault D ' _a=0, D ' _b=N, D ' _c=0, according to localization of fault table two, can determine that open fault has occurred T4.Arriving this, is switch transistor T 1 before can determining, open fault occurs T4 simultaneously.

H) t=2～2.2s, as shown in Figure 6, phase current Ia occurs that negative half-wave, Ib occur that negative half-wave appears in positive half-wave, Ic.Detection variable d _a>=0.08, d _b≤-0.08, | d _c| < 0.08, a _a> 0.93, a _b> 0.93, a _c> 0.93; So indicating fault D _a=P, D _b=N, D _c=0, A _a=A _b=A _c=H.According to localization of fault table one, may be T1, T4 or T1, T5 or T1, T4, there is open fault in T5 simultaneously.Similarly, confirmable is that fault has occurred switch transistor T 1 certainly, therefore utilizes the 4th brachium pontis to replace the brachium pontis at T1 place, and then reconstruct inverter detects again.Now, there is positive half-wave in phase current Ib, and negative half-wave, detection variable d appear in Ic _b≤-0.08, d _c>=0.08, indicating fault D ' _b=N, D ' _c=P, according to localization of fault table two, can determine T4, and open fault has occurred T5 simultaneously.Arriving this, is switch transistor T 1 before can determining, T4, and there is open fault in T5 simultaneously.

In motor actual moving process, rotating speed or load meeting change, and the expectation voltage that vector control module obtains also can change.The present invention is based on expecting that voltage carries out fault detect, but can motor speed change procedure or load variations process in there is the phenomenon of wrong report fault.

Fig. 7 is motor three-phase current, detection variable d in motor speed change procedure _nand a _noscillogram.As shown in Figure 7, t=1.2～1.4s, rotating speed is 1000rpm; T=1.5～1.6s, rotating speed becomes 1390rpm; T=1.8～2s, rotating speed becomes 1000rpm.And in whole rotation speed change process, although indicating fault exists certain fluctuation, can even not exceed threshold value by deviation normal value, can not produce the phenomenon of wrong report fault.

Fig. 8 is motor three-phase current, detection variable d in load variations process _nand a _noscillogram.As shown in Figure 8, t=1～1.4s, system does not load, and is light condition; T=1.4s, System Sudden is loaded into nominal load; T=1.8s, System Sudden variable load is light condition.In whole load variations process, although indicating fault exists certain fluctuation, can even not exceed threshold value by deviation normal value, can not produce the phenomenon of wrong report fault.

Although above the illustrative embodiment of the present invention is described; so that those skilled in the art understand the present invention; but should be clear; the invention is not restricted to the scope of embodiment; to those skilled in the art; as long as various variations appended claim limit and definite the spirit and scope of the present invention in, these variations are apparent, all utilize innovation and creation that the present invention conceives all at the row of protection.

Claims (4)

1. a three-phase inverter open fault detection method for phase redundancy fault-tolerant architecture, is characterized in that, comprises the following steps:

S1: drive closed-loop control system and obtain expectation voltage from motor

then will through Clark, coordinate transform is converted into three-phase reference voltage

S2: calculate detection variable d _n:

$d_n=\frac{<u_n^{*}>}{<\left|u_n^{*}\right|>}$

Wherein,

that three-phase is expected voltage

mean value,

it is three-phase voltage the mean value of absolute value;

S3: calculate detection variable a _n:

$a_a=\frac{2<\left|u_a^{*}\right|>}{<\left|u_b^{*}\right|>+<\left|u_c^{*}\right|>}$

$a_b=\frac{2<\left|u_b^{*}\right|>}{<\left|u_a^{*}\right|>+<\left|u_c^{*}\right|>}$

$a_c=\frac{2<\left|u_c^{*}\right|>}{<\left|u_a^{*}\right|>+<\left|u_b^{*}\right|>}$

S4: set detection variable d _nwith detection variable a _nthreshold value k _mand k _d, judgement obtains indicating fault D _nand A _n:

$D_n=\left\{\begin{array}{cc}N& d_n\&le;-k_m\\ 0& \left|d_n\right|<k_m\\ P& d_n\&GreaterEqual;k_m\end{array}\right.$

$A_n=\left\{\begin{array}{cc}H& a_n>k_d\\ L& a_n\&le;k_d\end{array}\right.$

S5: according to the indicating fault D obtaining _nand A _nthe switching tube of Search and Orientation generation open fault in localization of fault table one.

2. three-phase inverter open fault detection method according to claim 1, is characterized in that, exists the fault of three kinds of likelihood of failure to adopt following methods further to locate in described localization of fault table one:

The brachium pontis of determining the switching tube place that open fault occurs is substituted with the 4th brachium pontis of redundancy, again obtain and expect that voltage calculates indicating fault D ' _n, according to the switching tube of localization of fault table two Search and Orientation generation open fault.

3. three-phase inverter open fault detection method according to claim 1, is characterized in that, described three-phase is expected voltage

mean value

three-phase voltage

the mean value of absolute value

computing formula be:

$<u_n^{*}>=\frac{w}{2\mathrm{\&pi;}}\underset{0}{\overset{\frac{2\mathrm{\&pi;}}{w}}{\&Integral;}}{u}_n^{*}\mathrm{dt}$

$<\left|u_n^{*}\right|>=\frac{w}{2\mathrm{\&pi;}}\underset{0}{\overset{\frac{2\mathrm{\&pi;}}{w}}{\&Integral;}}\left|u_n^{*}\right|\mathrm{dt}$

Wherein, w represents the stator current angular frequency of motor.

4. three-phase inverter open fault detection method according to claim 1, is characterized in that, described detection variable threshold value k _m=0.08, k _d=0.93.

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