CN113189436A

CN113189436A - Three-level inverter power module detection circuit and detection method

Info

Publication number: CN113189436A
Application number: CN202110597152.4A
Authority: CN
Inventors: 许颇; 程琨; 张玉娟; 王一鸣
Original assignee: Ginlong Technologies Co Ltd
Current assignee: Ginlong Technologies Co Ltd
Priority date: 2021-05-31
Filing date: 2021-05-31
Publication date: 2021-07-30

Abstract

The invention discloses a three-level inverter power module detection circuit which comprises a support capacitor and an inverter bridge arm unit, wherein the inverter bridge arm unit is respectively connected with two end parts of the support capacitor and a midpoint N point, a voltage division unit is arranged between a midpoint O point on the alternating current side of the inverter bridge arm unit and a positive pole and a negative pole of a bus of a direct-current power supply respectively, a first voltage detector is arranged at two ends of any one of a first voltage division unit and a second voltage division unit, and a second voltage detection element is arranged between the N point and the direct-current power supply. A voltage division unit is arranged between a midpoint O point of an alternating current side of an inverter bridge arm unit and a positive electrode and a negative electrode of a bus of a direct current power supply respectively, two ends of one voltage division unit are connected with a first voltage detector in parallel, a second voltage detector is arranged between an N point and the direct current power supply, the power element and the voltage division unit are controlled to be closed or opened, detection values of the two voltage detectors and a theoretical voltage value of the power module in normal state are compared, whether the power module is in fault or not is judged, and the number of used detection elements is small.

Description

Three-level inverter power module detection circuit and detection method

Technical Field

The invention relates to the technical field of three-level inverters, in particular to a detection circuit and a detection method for a power module of a three-level inverter.

Background

The three-level inverter is an inversion system which is widely applied at present, the inverter usually detects parameters such as grid voltage, frequency, phase sequence and the like before grid-connected power generation, and grid-connected power generation is performed only after output parameters of the inverter are synchronous with parameters of a grid. But neglects the detection of the power module in the system, the power module is the core circuit of the inverter, if the detection is not carried out, the inverter can not be normally connected to the grid for power generation.

Disclosure of Invention

In view of the above analysis, the present invention provides a three-level inverter power module detection circuit and a detection method to solve the deficiencies of the prior art.

The invention is mainly realized by the following technical scheme:

the invention provides a three-level inverter power module detection circuit, which comprises a support capacitor and an inverter bridge arm unit, the support capacitor comprises a first support capacitor and a second support capacitor, the first support capacitor and the second support capacitor are connected in series and then are connected in parallel at two sides of the direct current power supply, the inverter bridge arm unit is respectively connected with two end parts of the supporting capacitor and the midpoint N point of the first supporting capacitor and the second supporting capacitor, a first voltage division unit is arranged between the midpoint O point of the alternating current side of the inverter bridge arm unit and the positive electrode of the bus of the direct current power supply, a second voltage division unit is arranged between the midpoint O point of the alternating current side of the inverter bridge arm unit and the negative pole of the bus of the direct current power supply, a first voltage detector is arranged at two ends of any one of the first voltage division unit and the second voltage division unit, and a second voltage detector is arranged between the N point and the negative pole or the positive pole of the bus of the direct-current power supply.

Furthermore, the inverter bridge arm unit comprises a first power element, a second power element, a third power element, a fourth power element, a first diode and a second diode, the first power element, the second power element, the third power element and the fourth power element are connected in series in sequence, the first end of the first power element is connected with the first end of the first capacitor, the second end of the fourth power element is connected with the second end of the second capacitor, after the first diode and the second diode are connected in series, the cathode of the first diode is connected with the connection point of the first power element and the second power element, the anode of the second diode is connected with the connection point of the third power element and the fourth power element, the connecting point of the first diode and the second diode is connected with the midpoint N point of the first supporting capacitor and the second supporting capacitor;

or, the first diode is replaced by a fifth power element, and the second diode is replaced by a sixth power element.

Furthermore, the first voltage division unit comprises a first matching resistor and a first switch which are connected in series, the first matching resistor is connected with a first end of the first power element, the first switch is connected with an O point between the second power element and the third power element, the second voltage division unit comprises a second matching resistor and a second switch which are connected in series, the second matching resistor is connected with an O point between the second power element and the third power element, and the second switch is connected with a second end of the fourth power element.

Furthermore, the first power element, the second power element, the third power element and the fourth power element are all an IGBT tube and a diode connected in anti-parallel;

or the first power element, the second power element, the third power element, the fourth power element, the fifth power element and the sixth power element are all IGBT tubes which are connected with one diode in an anti-parallel mode;

the IGBT tube can be replaced by a MOSFET.

Furthermore, third end parts of the first power element, the second power element, the third power element and the fourth power element are all connected with a driving circuit;

or the third end parts of the first power element, the second power element, the third power element, the fourth power element, the fifth power element and the sixth power element are all connected with a driving circuit.

Furthermore, the first switch and the second switch are respectively connected with the control unit;

preferably, the electronic switch is an IGBT tube, a MOSFET or a triode, and the mechanical switch is a relay or a controllable contactor.

The invention also provides a method for detecting the power module of the three-level inverter, which comprises the following steps:

the voltage value of the DC power supply is set to Vdc, and the voltage value of the two points N, O is V_NOWhen each power element and each voltage division unit can work normally, the first voltage division unit is connected with the first power element and the second power element in parallel, other voltage division units and each power element are disconnected, the impedance of the first voltage division unit is matched, the detection value of the first voltage detector is s1 Vdc, s 1E (1/2, 1), the second voltage division unit is connected with the third power element and the fourth power element in parallel, other voltage division units and each power element are disconnected, the impedance of the second voltage division unit is matched, the detection value of the first voltage detector is s 2Vdc, s 2E (0, 1/2);

respectively acquiring theoretical detection values of a first voltage detector and a second voltage detector under different test states when each power element and the voltage division unit are normally conducted;

when a second power element, a first diode or a second power element and a fifth power element are detected, a second voltage division unit is connected with a third power element and a fourth power element which are connected in series in parallel, the first voltage division unit is disconnected, each power element is turned off, the obtained detection value of a first voltage detector is compared with a theoretical voltage value s 2Vdc under the same detection state, the obtained detection value of a second voltage detector is compared with a theoretical voltage value 1/2Vdc under the same detection state, if the detection values are the same, the next step is carried out, and if the detection values are different, the detection is stopped;

then the second power element is controlled to be conducted, and after voltage balance is achieved, the obtained detection value of the first voltage detector and the theoretical voltage value V under the same detection state are obtained₂-V_NOComparing, wherein the detection values of the first voltage detector and the second voltage detector are both less than 1/2Vdc, and if the conditions are uniformIf the anti-parallel diodes on the second power element, the first diode or the second power element and the fifth power element are normal, if the anti-parallel diodes on the second power element, the first diode or the second power element and the fifth power element are different, the second power element or the first diode is in fault, or the anti-parallel diodes on the second power element or the fifth power element are in fault, and the detection is stopped;

on the basis that anti-parallel diodes on the second power element, the first diode or the second power element and the fifth power element are normal, when the first power element is detected, the second voltage division unit is disconnected, the first power element is controlled to be connected, the detected value of the first voltage detector is compared with the theoretical voltage value Vdc in the same detection state, if the detected value is the same as the theoretical voltage value Vdc, the first power element is normal, and if the detected value is different from the theoretical voltage value Vdc, the first power element is failed, and the detection is stopped;

when detecting the anti-parallel diodes on the third power element, the second diode or the third power element and the sixth power element, keeping the connection state of the first voltage division unit, turning off other voltage division units and each power element, comparing the obtained detection value of the first voltage detector with a theoretical voltage value s1 Vdc under the same detection state, comparing the obtained detection value of the second voltage detector with a theoretical voltage value 1/2Vdc under the same detection state, if the detection values are the same, entering the next step, and if the detection values are different, stopping the detection;

then the third power element is controlled to be conducted, and after voltage balance is achieved, the obtained detection value of the first voltage detector and the theoretical voltage value V under the same detection state are obtained_NO+V₂Comparing, wherein the detection values of the first voltage detector and the second voltage detector are both greater than 1/2Vdc, if the conditions are consistent, the anti-parallel diodes on the third power element, the second diode or the third power element and the sixth power element are normal, if the conditions are different, the third power element or the second diode is in fault, or the anti-parallel diodes on the third power element or the sixth power element are in fault, and stopping detection;

and on the basis that the anti-parallel diodes on the third power element, the second diode or the third power element and the sixth power element are normal, when the fourth power element is detected, the first voltage division unit is disconnected, the fourth power element is controlled to be connected, the detected value of the first voltage detector is compared with the theoretical voltage value 0 in the same detection state, if the detected value is the same as the theoretical voltage value, the fourth power element is normal, and if the detected value is different from the theoretical voltage value, the fourth power element is failed, and the detection is stopped.

Further, when the first diode is replaced by a fifth power element and the second diode is replaced by a sixth power element, the method further comprises the following steps after the first power element is detected:

when the anti-parallel diodes on the sixth power element and the third power element are detected on the basis that the anti-parallel diodes on the second power element and the fifth power element are normal, the connection state of the second voltage division unit is kept, the second power element is switched off,

then the sixth power element is controlled to be conducted, and after voltage balance is achieved, the obtained detection value of the first voltage detector and the theoretical voltage value V under the same detection state are obtained₂-V_NOAnd comparing, wherein the detection values of the first voltage detector and the second voltage detector are both smaller than 1/2Vdc, if the conditions are consistent, the anti-parallel diodes on the sixth power element and the third power element are normal, and if the conditions are different, the anti-parallel diodes on the sixth power element or the third power element are failed, and the detection is stopped.

Further, when the first diode is replaced by a fifth power element and the second diode is replaced by a sixth power element, the method further comprises the following steps after the fourth power element is detected:

when the anti-parallel diodes on the fifth power element and the second power element are detected on the basis that the anti-parallel diodes on the third power element and the sixth power element are normal, the connection state of the first voltage division unit is kept, the third power element is switched off,

then the fifth power element is controlled to be conducted, and the obtained detection value of the first voltage detector and the theoretical voltage value V under the same detection state are obtained_NO+V₂When the detected values of the first voltage detector and the second voltage detector are both greater than 1/2Vdc, the fifth power element and the second power element are both in accordance with the same conditionThe anti-parallel diode on the fifth power element or the second power element is normal, if the anti-parallel diode on the fifth power element or the second power element is not normal, the detection is stopped.

Further, the power elements to be detected are turned on by applying pulse signals thereto, respectively.

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

the invention provides a detection circuit and a detection method for a three-level inverter power module.A voltage division unit is respectively arranged between a midpoint O point on the alternating current side of an inverter bridge arm unit and the positive pole and the negative pole of a bus of a direct-current power supply, a first voltage detector is connected in parallel with two ends of at least one voltage division unit, a second voltage detector is arranged between an N point and the positive pole or the negative pole of the bus of the direct-current power supply, and whether a power module has a fault or not is judged by respectively controlling the power element and the voltage division unit to be switched on or switched off and then comparing the detection values of the two voltage detectors with the theoretical voltage value of the power module in normal state.

Drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings needed to be used in the description of the embodiments will be briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without creative efforts.

FIG. 1 is a schematic circuit diagram of a three-level inverter power module detection circuit provided by an embodiment of the present invention when the power module is of the NPC type;

FIG. 2(a) is a schematic circuit diagram of the second switch in FIG. 1 when closed according to an embodiment of the present invention;

FIG. 2(b) is a pulse test chart of the second switch in FIG. 2 (a);

fig. 3(a) is a schematic circuit diagram of the second switch in fig. 1 being closed and the second power element being conductive according to the embodiment of the present invention;

FIG. 3(b) is a pulse test plot of the second switch closure and second power element of FIG. 3 (a);

FIG. 4(a) is a schematic circuit diagram of the first switch in FIG. 1 when closed according to an embodiment of the present invention;

FIG. 4(b) is a pulse test chart of the first switch in FIG. 4 (a);

fig. 5(a) is a schematic circuit diagram of the first switch in fig. 1 being closed and the third power element being turned on according to the embodiment of the present invention;

FIG. 5(b) is a pulse test chart of the first switch, the third power element in FIG. 5 (a);

fig. 6(a) is a schematic circuit diagram illustrating the power components and switches in fig. 1 when they are turned off according to an embodiment of the present invention;

FIG. 6(b) is a pulse test chart of FIG. 6(a) with the power devices and switches off;

fig. 7(a) is a schematic circuit diagram of the first power element and the second power element in fig. 1 when they are turned on according to the embodiment of the present invention;

FIG. 7(b) is a pulse test chart of the first power element and the second power element in FIG. 7 (a);

fig. 8(a) is a schematic circuit diagram of the third power element and the fourth power element in fig. 1 when they are turned on according to the embodiment of the present invention;

FIG. 8(b) is a pulse test chart of the third power element and the fourth power element in FIG. 8 (a);

FIG. 9 is a schematic circuit diagram of a three-level inverter power module detection circuit according to an embodiment of the present invention when the power module is of the ANPC type;

FIG. 10(a) is a schematic diagram of the circuit of FIG. 9 with the second switch closed according to the embodiment of the present invention;

FIG. 10(b) is a pulse test chart of the second switch in FIG. 10 (a);

fig. 11(a) is a schematic circuit diagram of the second switch in fig. 9 being closed and the second power element being turned on according to the embodiment of the present invention;

FIG. 11(b) is a pulse test chart of the second switch, second power element in FIG. 11 (a);

fig. 12(a) is a schematic circuit diagram of the sixth power element in fig. 9 when the second switch is closed and the sixth switch is turned on according to the embodiment of the present invention;

FIG. 12(b) is a pulse test chart of the second switch, sixth power element in FIG. 12 (a);

FIG. 13(a) is a schematic circuit diagram of the first switch in FIG. 9 during a close test according to an embodiment of the present invention;

FIG. 13(b) is a pulse test chart of the first switch in FIG. 13 (a);

fig. 14(a) is a schematic circuit diagram of the first switch in fig. 9 being closed and the third power element being turned on according to the embodiment of the present invention;

fig. 14(b) is a pulse test chart of the first switch, the third power element in fig. 14 (a);

fig. 15(a) is a schematic circuit diagram of the first switch in fig. 9 being closed and the fifth power element being turned on according to the embodiment of the present invention;

FIG. 15(b) is a pulse test chart of the first switch, fifth power element in FIG. 15 (a);

fig. 16(a) is a schematic circuit diagram illustrating the power devices and switches in fig. 9 when they are turned off according to an embodiment of the present invention;

fig. 16(b) is a pulse test chart when each power element and switch in fig. 16(a) are turned off;

fig. 17(a) is a schematic circuit diagram of the first power element and the second power element in fig. 9 when they are turned on according to the embodiment of the present invention;

fig. 17(b) is a pulse test chart of the first power element and the second power element in fig. 17 (a);

fig. 18(a) is a schematic circuit diagram illustrating the third power element and the fourth power element in fig. 9 when they are turned on according to an embodiment of the present invention;

fig. 18(b) is a pulse test chart of the third power element and the fourth power element in fig. 18 (a).

Detailed Description

In order that those skilled in the art will better understand the invention and thus more clearly define the scope of the invention as claimed, it is described in detail below with respect to certain specific embodiments thereof. It should be noted that the following is only a few embodiments of the present invention, and the specific direct description of the related structures is only for the convenience of understanding the present invention, and the specific features do not of course directly limit the scope of the present invention. Such alterations and modifications as are made obvious by those skilled in the art and guided by the teachings herein are intended to be within the scope of the invention as claimed.

The invention is further described with reference to the following figures and specific examples.

Example 1

The invention provides a three-level inverter power module detection circuit, which comprises a support capacitor and an inverter bridge arm unit, wherein the support capacitor comprises a first support capacitor C1 and a second support capacitor C2, the first support capacitor C1 and the second support capacitor C2 are connected in series and then are connected in parallel at two sides of a direct current power supply DC, the inverter bridge arm unit is respectively connected with two end parts of the support capacitor and the first support capacitor C1, the midpoint N of the second supporting capacitor C2 is connected, a first voltage division unit is arranged between the midpoint O of the alternating current side of the inverter bridge arm unit and the positive pole of the bus of the direct current power supply DC, a second voltage division unit is arranged between the midpoint O of the alternating current side of the inverter bridge arm unit and the negative pole of the bus of the direct current power supply DC, a first voltage detector is arranged at any two ends of the first voltage division unit and the second voltage division unit, and a second voltage detector is arranged between the N point and the negative pole or the positive pole of the bus of the direct current power supply. Wherein the direct current power supply DC is an adjustable direct current power supply. The capacitance values of C1 and C2 are equal.

As shown in fig. 1, preferably, the inverter bridge arm unit includes a first power element T1, a second power element T2, a third power element T3, a fourth power element T4, a first diode D1, and a second diode D2, the first power element T1, the second power element T2, the third power element T3, and the fourth power element T4 are sequentially connected in series, a first end of the first power element T1 is connected to a first end of a first capacitor, a second end of the fourth power element T4 is connected to a second end of a second capacitor, the first diode D1 and the second diode D2 are connected in series, a negative electrode of the first diode D1 is connected to a connection point of the first power element T1 and the second power element T2, a positive electrode of the second diode D2 is connected to a connection point of the third power element T3 and the fourth power element T4, and a connection point of the first diode D1 and the first diode D2 is connected to a connection point of the first capacitor C1, The midpoint N of the second support capacitor C2 is connected.

Specifically, the first power element T1, the second power element T2, the third power element T3, and the fourth power element T4 are all one IGBT and one diode connected in anti-parallel. The IGBT tube may be replaced with a MOSFET.

Specifically, the third ends of the first power element T1, the second power element T2, the third power element T3, and the fourth power element T4 are all connected to the driving circuit.

As shown in fig. 9, it is preferable that the first diode D1 in the inverter arm unit is replaced with a fifth power element T5, and the second diode D2 is replaced with a sixth power element T6.

Specifically, the first power element T1, the second power element T2, the third power element T3, the fourth power element T4, the fifth power element T5, and the sixth power element T6 are all one IGBT tube and one diode connected in anti-parallel. The IGBT tube may be replaced with a MOSFET.

Specifically, the third ends of the first power element T1, the second power element T2, the third power element T3, the fourth power element T4, the fifth power element T5, and the sixth power element T6 are all connected to the driving circuit.

Preferably, the first voltage dividing unit includes a first matching resistor R1 and a first switch K1 connected in series, the first matching resistor R1 is connected to a first end of the first power element T1, the first switch K1 is connected to an O point between the second power element T2 and the third power element T3, the second voltage dividing unit includes a second matching resistor R2 and a second switch K2 connected in series, the second matching resistor R2 is connected to an O point between the second power element T2 and the third power element T3, and the second switch K2 is connected to a second end of the fourth power element T4.

Preferably, the first switch K1 and the second switch K2 are electronic switches or mechanical switches.

Furthermore, the electronic switch is an IGBT (insulated gate bipolar transistor) tube or an MOSFET (metal oxide semiconductor field effect transistor) or a triode, and the mechanical switch is a relay or a controllable contactor.

Specifically, the first switch K1 and the second switch K2 are respectively connected to the control unit, and the control switches are turned on.

As shown in fig. 2-8, when the power module is NPC type, the self-test procedure is as follows:

1) presetting the DC power supply DC with the voltage value of Vdc, wherein the voltage value of two points N, O is V_NOThe first supporting capacitor C1 and the second supporting capacitor C2 are charged to saturation, theoretical values of the first voltage detector V1 and the second voltage detector V2 when the power elements and the voltage dividing unit are normally turned on are respectively obtained, and impedance of the first matching resistor R1 and impedance of the second matching resistor R2 are matched according to actual conditions, wherein specific matching steps are detailed in the content of the detection method;

2) IGBT tube (T2) and diode (D1) self-test:

when the switch (K2) is closed, the IGBT transistors (T1, T2, T3, T4) are turned off, and the switch (K1) is turned off, if the detected voltage value of the first voltage detector V1 is the same as the theoretical voltage value, and is a ═ s2 × Vdc, s2 ∈ (0, 1/2), the detected voltage value of the second voltage detector V2 is the same as the theoretical voltage value, and is 1/2 Vdc; switching on the IGBT (T2) under the above conditions, and when the voltage balance is reached, if the voltage detected by the first voltage detector V1 is the same as the theoretical voltage b and is V₂-V_NOAt this time, the detection values of the first voltage detector V1 and the second voltage detector V2 are both smaller than 1/2Vdc, and if the conditions are consistent, the IGBT (T2) and the diode (D1) are intact; otherwise, the IGBT tube (T2) or the diode (D1) fails, and the detection is stopped.

3) The IGBT tube (T1) is self-tested when the IGBT tube (T2) and the diode (D1) are in good condition:

under the condition of the step 2), the switch (K2) is turned off, then the IGBT tube (T1) is controlled to be turned on, and at the moment, the detection voltage value of the first voltage detector V1 is the same as the theoretical voltage value f of V1 and is Vdc; namely the IGBT tube (T1) is intact; otherwise, the IGBT tube (T1) is in fault, and the detection is stopped.

4) IGBT tube (T3) and diode (D2) self-test:

when the switch (K1) is closed, the IGBT tubes (T1, T2, T3, T4) are turned off, the switch (K2) is turned off, and the first voltage detector V1 detects a voltage value identical to the theoretical voltage value and c ═ s1 × Vdc, s1 ∈ (1/2, 1), the second voltage detector V2 detects a value identical to the theoretical voltage value,1/2 Vdc; switching on the IGBT (T3) under the above conditions, and when the voltage balance is reached, if the voltage detected by the first voltage detector V1 is the same as the theoretical voltage d and is V_NO+V₂At this time, the detection values of the first voltage detector V1 and the second voltage detector V2 are both larger than 1/2Vdc, and if the conditions are consistent, the IGBT (T3) and the diode (D2) are intact; otherwise, the IGBT tube (T3) or the diode (D2) fails, and the detection is stopped.

5) The IGBT tube (T4) is self-tested when the IGBT tube (T3) and the diode (D2) are in good condition:

under the condition of the step 4), the switch (K1) is turned off, then the IGBT tube (T4) is turned on, and the detection voltage value of the first voltage detector V1 is the same as the theoretical voltage value g of V1 and is 0; namely the IGBT tube (T4) is intact; otherwise, the IGBT tube (T4) is in fault, and the detection is stopped.

As shown in fig. 10-18, when the power module is of the ANPC type, the self-test procedure is as follows:

1) presetting the DC power supply DC with the voltage value of Vdc, wherein the voltage value of two points N, O is V_NOThe first supporting capacitor C1 and the second supporting capacitor C2 are charged to saturation, the theoretical values of the V1 of the first voltage detector and the theoretical values of the V2 of the second voltage detector are respectively obtained when each power element and the voltage dividing unit are normally turned on, the impedances of the first matching resistor R1 and the second matching resistor R2 are matched according to actual conditions, and specific matching steps are detailed in the content of the detection method;

2) IGBT tube (T2) and IGBT tube (T5) are anti-parallel diode self-checking:

the switch (K2) is closed, the IGBT tubes (T1, T2, T3, T4, T5 and T6) are turned off, the switch (K1) is turned off, if the detection voltage value of the first voltage detector V1 is the same as the theoretical voltage value and is a-s 2-Vdc, s2 epsilon (0, 1/2), and the detection voltage value of the second voltage detector V2 is the same as the theoretical voltage value and is 1/2 Vdc; switching on the IGBT (T2) under the above conditions, and when the voltage balance is reached, if the voltage detected by the first voltage detector V1 is the same as the theoretical voltage b and is V₂-V_NOAt this time, the detection values of the first voltage detector V1 and the second voltage detector V2 are both smaller than 1/2Vdc, and if the conditions are consistent, the anti-parallel diodes of the IGBT (T2) and the IGBT (T5) are intact; otherwise IGBT tube (1)T2) or the IGBT tube (T5) fails, and detection is stopped.

3) The IGBT tube (T1) self-test is carried out under the condition that the IGBT tube (T2) and the IGBT tube (T5) are in good anti-parallel connection:

under the condition of the step 2), the switch (K2) is turned off, then the IGBT tube (T1) is controlled to be turned on, and at the moment, the detection voltage value of the first voltage detector V1 is the same as the theoretical voltage value h of V1 and is Vdc; namely the IGBT tube (T1) is intact; otherwise, the IGBT tube (T1) is in fault, and the detection is stopped.

4) IGBT tube (T6) and IGBT tube (T3) are anti-parallel diode self-checking:

under the condition of the step 2), switching off the IGBT (T2), switching on the IGBT (T6), and after voltage balance is achieved, if the voltage value detected by the first voltage detector V1 is the same as the theoretical voltage value c and is V₂-V_NOAt this time, the detection values of the first voltage detector V1 and the second voltage detector V2 are both smaller than 1/2Vdc, and if the conditions are consistent, the anti-parallel diodes of the IGBT (T6) and the IGBT (T3) are intact; otherwise, the IGBT tube (T6) or the IGBT tube (T3) is in anti-parallel diode fault, and the detection is stopped.

5) IGBT tube (T3) and IGBT tube (T6) are anti-parallel diode self-checking:

when the switch (K1) is closed, the IGBT tubes (T1, T2, T3, T4, T5 and T6) are turned off and the switch (K2) is turned off, if the detected voltage value of the first voltage detector V1 is the same as the theoretical voltage value and d is s1 Vdc, s1 e (1/2, 1), the detected value of the second voltage detector V2 is the same as the theoretical voltage value and 1/2 Vdc; switching on the IGBT (T3) under the above conditions, and when the voltage balance is reached, if the voltage detected by the first voltage detector V1 is the same as the theoretical voltage e and is V_NO+V₂At this time, the detection values of the first voltage detector V1 and the second voltage detector V2 are both larger than 1/2Vdc, and if the conditions are consistent, the anti-parallel diodes of the IGBT tube (T3) and the IGBT tube (T6) are intact; otherwise, the IGBT tube (T3) or the IGBT tube (T6) is in anti-parallel diode fault, and the detection is stopped.

6) The IGBT tube (T4) self-test is carried out under the condition that the IGBT tube (T3) and the IGBT tube (T6) are in good anti-parallel connection:

under the condition of the step 5), the switch (K1) is turned off, then the IGBT tube (T4) is turned on, and the detection voltage value of the first voltage detector V1 is the same as the theoretical voltage value i of V1 and is 0; namely the IGBT tube (T4) is intact; otherwise, the IGBT tube (T4) is in fault, and the detection is stopped.

7) IGBT tube (T5) and IGBT tube (T2) are anti-parallel diode self-checking:

under the condition of the step 5), switching off the IGBT (T3), switching on the IGBT (T5), and after voltage balance is achieved, if the voltage value detected by the first voltage detector V1 is the same as the theoretical voltage value f and is V_NO+V₂At this time, the detection values of the first voltage detector V1 and the second voltage detector V2 are both larger than 1/2Vdc, and if the conditions are consistent, the anti-parallel diodes of the IGBT tube (T5) and the IGBT tube (T2) are intact; otherwise, the IGBT tube (T5) or the IGBT tube (T2) is in anti-parallel diode fault, and the detection is stopped.

And stopping detection when any IGBT tube fails.

the voltage value of the DC power supply DC is set to Vdc, and the voltage value of the two points N, O is V_NOWhen each power element and voltage dividing unit can work normally, the first voltage dividing unit is connected in parallel with the first power element T1 and the second power element T2, other voltage dividing units and each power element are disconnected, the impedance of the first voltage dividing unit is matched, the detection value of the first voltage detector V1 is s1 Vdc and s1 e (1/2, 1), the second voltage dividing unit is connected in parallel with the third power element and the fourth power element T4, other voltage dividing units and each power element are disconnected, the impedance of the second voltage dividing unit is matched, the detection value of the first voltage detector V1 is s 2Vdc and s2 e (0, 1/2);

respectively acquiring theoretical detection values of a first voltage detector V1 and a second voltage detector V2 in different test states when each power element and the voltage division unit are normally conducted;

when detecting a second power element T2, a first diode or a second power element T2 and a fifth power element T5, connecting a second voltage division unit in parallel with a third power element T3 and a fourth power element T4 which are connected in series, disconnecting the first voltage division unit, turning off each power element, comparing the obtained detection value of a first voltage detector V1 with a theoretical voltage value s 2Vdc in the same detection state, comparing the obtained detection value of a second voltage detector with the theoretical voltage value 1/2Vdc in the same detection state, entering the next step if the two phases are the same, and stopping detection if the two phases are different;

then the second power element T2 is controlled to be conducted, and after voltage balance is achieved, the obtained detection value of the first voltage detector V1 and the theoretical voltage value V under the same detection state are obtained₂-V_NOComparing, wherein detection values of the first voltage detector V1 and the second voltage detector V2 are both smaller than 1/2Vdc, if conditions are consistent, the anti-parallel diodes on the second power element T2, the first diode or the second power element T2 and the fifth power element T5 are normal, if the conditions are different, the second power element T2 or the first diode is in fault, or the anti-parallel diodes on the second power element T2 or the fifth power element T5 are in fault, and stopping detection;

on the basis that anti-parallel diodes on the second power element T2, the first diode or the second power element T2 and the fifth power element T5 are normal, when the first power element T1 is detected, the second voltage division unit is disconnected, then the first power element T1 is controlled to be connected, the detected value of the first voltage detector V1 is obtained and compared with a theoretical voltage value Vdc in the same detection state, if the detected value is the same, the first power element T1 is normal, and if the detected value is different, the first power element T1 is in fault, and detection is stopped;

when the anti-parallel diodes on the third power element T3, the second diode or the third power element T3, the sixth power element T6 are detected, the connected state of the first voltage dividing unit is maintained, other voltage dividing units and each power element are turned off, the acquired detection value of the first voltage detector V1 is compared with the theoretical voltage value s1 × Vdc in the same detection state, the acquired detection value of the second voltage detector V2 is compared with the theoretical voltage value 1/2Vdc in the same detection state, if the detection values are the same, the next step is carried out, and if the detection values are different, the detection is stopped;

then the third power element T3 is controlled to be conducted, and after voltage balance is achieved, the obtained first voltage is detectedThe detection value of the device V1 is equal to the theoretical voltage value V under the same detection state_NO+V₂Comparing, wherein detection values of the first voltage detector V1 and the second voltage detector V2 are both larger than 1/2Vdc, if conditions are consistent, the anti-parallel diodes on the third power element T3, the second diode or the third power element T3 and the sixth power element T6 are normal, and if the conditions are different, the third power element T3 or the second diode is failed, or the anti-parallel diodes on the third power element T3 or the sixth power element T6 are failed, and stopping detection;

on the basis that the anti-parallel diodes on the third power element T3, the second diode or the third power element T3 and the sixth power element T6 are normal, when the fourth power element T4 is detected, the first voltage division unit is disconnected, then the fourth power element T4 is controlled to be connected, the detected value of the first voltage detector V1 is compared with the theoretical voltage value under the same detection state, if the detected value is the same, the fourth power element T4 is normal, and if the detected value is different, the fourth power element T4 is in fault, and the detection is stopped.

Wherein, S1 and S2 are both voltage coefficients. S1 and S2 vary according to the resistance of the first divider resistor R1 and the second divider resistor R2, and the impedances of the voltage dividing branches are different, and the voltages respectively shared by the power elements connected in parallel are also different.

Preferably, the power elements to be detected are turned on by applying pulse signals thereto, respectively.

When the power module is of NPC type, specifically, the method respectively obtains the theoretical values of the first voltage detector V1 and the second voltage detector V2 under different test states when each power element and the voltage dividing branch are normally turned on, and includes the following steps:

controlling a second voltage division circuit to be connected into the circuit, disconnecting each power element and other voltage division branches, and matching the impedance of a second matching resistor R2, so that the detection value of a first voltage detector V1 is a theoretical voltage value a in the current test state of s 2Vdc, s2 is (0, 1/2) e, and the detection value of a second voltage detector V2 is a theoretical voltage value in the current test state of 1/2 Vdc;

in the last step, the second power device T2 is controlled to be turned on, and the first voltage is detectedThe detection value of the detector V1 is the theoretical voltage value b under the current test state, and since b will gradually increase from a, while the detection value of the second voltage detection element V2 is the theoretical voltage value under the current test state, the theoretical voltage value will gradually decrease from 1/2Vdc until V₁＝V₂-V_NOVoltage balance is achieved, and the theoretical voltage values of the first voltage detection element V1 and the second voltage detection element V2 are both smaller than 1/2 Vdc;

controlling the first voltage division circuit to be connected into the circuit, disconnecting each power element and other voltage division branches, and matching the impedance of the first matching resistor R1, so that the detection value of the first voltage detector V1 is the theoretical voltage value c under the current test state of s1 Vdc, s 1E (1/2, 1), and the detection value of the second voltage detector V2 is the theoretical voltage value under the current test state of 1/2 Vdc;

under the condition of the last step, the third power element T3 is controlled to be turned on, and the detection value of the first voltage detector V1 is the theoretical voltage value d under the current test state, and since d is gradually decreased from c, and the detection value of the second voltage detector V2 is the theoretical voltage value under the current test state, the theoretical voltage value is gradually increased from 1/2Vdc until V₁＝V_NO+V₂Voltage balance is achieved, and the theoretical voltage values of the first voltage detection element V1 and the second voltage detection element V2 are both larger than 1/2 Vdc;

disconnecting each power element and the voltage dividing branch, wherein the detection value of the first voltage detector V1 is the theoretical voltage value e under the current test state, which is 1/2 Vdc;

controlling the first power element T1 and the second power element T2 to be turned on, and the other power elements and the voltage dividing branch to be turned off, wherein a detection value of the first voltage detector V1 is a theoretical voltage value f ═ Vdc in a current test state;

and controlling the third power element T3 and the fourth power element T4 to be turned on, and the other power elements and the voltage dividing branch to be turned off, wherein the detection value of the first voltage detector V1 is that the theoretical voltage value g under the current test state is 0.

When the first diode is replaced by the fifth power element T5 and the second diode is replaced by the sixth power element T6, the following steps are preferably further included after the first power element T1 is detected:

on the basis that the anti-parallel diodes on the second power element T2 and the fifth power element T5 are normal, when the anti-parallel diodes on the sixth power element T6 and the third power element T3 are detected, the connection state of the second voltage division unit is kept, the second power element T2 is switched off, the sixth power element T6 is controlled to be switched on, and after voltage balance is achieved, the acquired detection value of the first voltage detector V1 and the theoretical voltage value V under the same detection state are switched on₂-V_NOIn this case, the detection values of the first voltage detector V1 and the second voltage detector V2 are both smaller than 1/2Vdc, and if the conditions are both the same, the anti-parallel diodes of the sixth power device T6 and the third power device T3 are normal, and if the conditions are not the same, the anti-parallel diodes of the sixth power device T6 or the third power device T3 are failed, and the detection is stopped.

When the first diode is replaced by the fifth power element T5 and the second diode is replaced by the sixth power element T6, the following steps are preferably further included after the fourth power element T4 is detected:

on the basis that the anti-parallel diodes on the third power element T3 and the sixth power element T6 are normal, when the anti-parallel diodes on the fifth power element T5 and the second power element T2 are detected, the connection state of the first voltage division unit is kept, the third power element is switched off, the fifth power element T5 is controlled to be switched on, and the acquired detection value of the first voltage detector V1 and the theoretical voltage value V in the same detection state are connected_NO+V₂In comparison, at this time, the detection values of the first voltage detector and the second voltage detector are both greater than 1/2Vdc, if the conditions are both the same, the anti-parallel diodes of the fifth power element T5 and the second power element T2 are normal, and if the conditions are not the same, the anti-parallel diodes of the fifth power element T5 or the second power element T2 are failed, and the detection is stopped.

When the power module is of an ANPC type, specifically, the method respectively obtains the theoretical values of the first voltage detector V1 and the second voltage detector V2 in different test states when each power element and the voltage dividing branch are normally turned on, and includes the following steps:

1) controlling a second voltage division circuit to be connected into a circuit, disconnecting each power element and other voltage division branches, and matching the impedance of a second matching resistor R2, so that the detection value of a first voltage detector V1 is a theoretical voltage value a under the current test state of s 2Vdc, s 2E (0, 1/2), and the detection value of a second voltage detector V2 is a theoretical voltage value under the current test state of 1/2 Vdc;

2) under the condition of step 1), the second power element T2 is controlled to be turned on, and the detection value of the first voltage detector V1 is the theoretical voltage value b under the current test state, and since b will gradually increase from a and the detection value of the second voltage detector V2 is the theoretical voltage value under the current test state, the theoretical voltage value will gradually decrease from 1/2Vdc until V₁＝V₂-V_NOVoltage balance is achieved, and the theoretical voltage values of the first voltage detection element V1 and the second voltage detection element V2 are both smaller than 1/2 Vdc;

3) under the condition of step 1), the sixth power element T6 is controlled to be turned on, and the detection value of the first voltage detector V1 is the theoretical voltage value c under the current test state, and since c will gradually increase from a, and the detection value of the second voltage detector V2 is the theoretical voltage value under the current test state, the theoretical voltage value will gradually decrease from 1/2Vdc until V₁＝V₂-V_NOVoltage balance is achieved, and the theoretical voltage values of the first voltage detection element V1 and the second voltage detection element V2 are both smaller than 1/2 Vdc;

4) controlling a first voltage division circuit to be connected into a circuit, disconnecting each power element and other voltage division branches, matching the impedance of a first matching resistor R1, enabling the detection value of a first voltage detector V1 to be a theoretical voltage value d which is s1 Vdc, s 1E (1/2, 1), and enabling the detection value of a second voltage detection element V2 to be a theoretical voltage value in the current test state and to be 1/2 Vdc;

5) under the condition of step 4), the third power element T3 is controlled to be turned on, and the detection value of the first voltage detector V1 is the theoretical voltage value e under the current test state, and since e gradually decreases from d, and the detection value of the second voltage detector V2 is the theoretical voltage value under the current test state, the theoretical voltage value gradually increases from 1/2VdcHigh, up to V₁＝V_NO+V₂Voltage balance is achieved, and the theoretical voltage values of the first voltage detection element V1 and the second voltage detection element V2 are both larger than 1/2 Vdc;

6) under the condition of step 4), the fifth power element T5 is controlled to be turned on, and the detection value of the first voltage detector V1 is the theoretical voltage value f under the current test state, and since f is gradually decreased from d, and the detection value of the second voltage detector V2 is the theoretical voltage value under the current test state, the theoretical voltage value is gradually increased from 1/2Vdc until V₁＝V_NO+V₂Voltage balance is achieved, and the theoretical voltage values of the first voltage detection element V1 and the second voltage detection element V2 are both larger than 1/2 Vdc;

7) disconnecting each power element and the voltage division branch, wherein the detection value of the first voltage detector V1 is the theoretical voltage value g under the current test state, which is 1/2 Vdc;

8) controlling the first power element T1 and the second power element T2 to be turned on, and the other power elements and the voltage dividing branch to be turned off, wherein a detection value of the first voltage detector V1 is a theoretical voltage value h ═ Vdc in a current test state;

9) and controlling the third power element T3 and the fourth power element T4 to be turned on, and the other power elements and the voltage dividing branch to be turned off, wherein the detection value of the first voltage detector V1 is that the theoretical voltage value i under the current test state is 0.

The above description is only a preferred embodiment of the present invention, and the protection scope of the present invention is not limited to the above embodiments, and all technical solutions belonging to the idea of the present invention belong to the protection scope of the present invention. It should be noted that modifications and embellishments within the scope of the invention may occur to those skilled in the art without departing from the principle of the invention, and are considered to be within the scope of the invention.

Claims

1. A three-level inverter power module detection circuit, characterized by: the inverter bridge arm comprises a support capacitor and an inverter bridge arm unit, wherein the support capacitor comprises a first support capacitor and a second support capacitor, the first support capacitor and the second support capacitor are connected in series and then connected in parallel to two sides of a direct-current power supply, the inverter bridge arm unit is respectively connected with two ends of the support capacitor and a midpoint N point of the first support capacitor and the second support capacitor, a first voltage division unit is arranged between a midpoint O point of an alternating current side of the inverter bridge arm unit and a bus anode of the direct-current power supply, a second voltage division unit is arranged between the midpoint O point of the alternating current side of the inverter bridge arm unit and a bus cathode of the direct-current power supply, a first voltage detector is arranged at any two ends of the first voltage division unit and the second voltage division unit, and a second voltage detector is arranged between the N point and the bus cathode or the bus anode of the direct-current power supply.

2. The three-level inverter power module detection circuit of claim 1, wherein: the inverter bridge arm unit comprises a first power element, a second power element, a third power element, a fourth power element, a first diode and a second diode, wherein the first power element, the second power element, the third power element and the fourth power element are sequentially connected in series, a first end of the first power element is connected with a first end of a first capacitor, a second end of the fourth power element is connected with a second end of a second capacitor, after the first diode and the second diode are connected in series, a cathode of the first diode is connected with a connection point of the first power element and the second power element, an anode of the second diode is connected with a connection point of the third power element and the fourth power element, and a connection point of the first diode and the second diode is connected with a midpoint N point of a first supporting capacitor and a second supporting capacitor;

3. The three-level inverter power module detection circuit of claim 2, wherein: the first voltage division unit comprises a first matching resistor and a first switch which are connected in series, the first matching resistor is connected with a first end portion of a first power element, the first switch is connected with an O point between a second power element and a third power element, the second voltage division unit comprises a second matching resistor and a second switch which are connected in series, the second matching resistor is connected with an O point between the second power element and the third power element, and the second switch is connected with a second end portion of a fourth power element.

4. The three-level inverter power module detection circuit of claim 2 or 3, wherein: the first power element, the second power element, the third power element and the fourth power element are all IGBT tubes which are connected with a diode in an anti-parallel mode;

the IGBT tube can be replaced by a MOSFET.

5. The three-level inverter power module detection circuit of claim 4, wherein: the third end parts of the first power element, the second power element, the third power element and the fourth power element are all connected with a driving circuit;

6. The three-level inverter power module detection circuit of claim 3, wherein: the first switch and the second switch are respectively connected with the control unit;

7. A method of detecting a three-level inverter power module detection circuit as claimed in any one of claims 1 to 6, comprising the steps of:

the voltage value of the DC power supply is set to Vdc, N,The voltage value of the two points O is V_NOWhen each power element and each voltage dividing unit can work normally, the first voltage dividing unit is connected with the first power element and the second power element in parallel, other voltage dividing units and each power element are disconnected, the impedance of the first voltage dividing unit is matched, the detection value s1 Vdc of the first voltage detector is enabled to be s 1E (1/2, 1), the second voltage dividing unit is connected with the third power element and the fourth power element in parallel, other voltage dividing units and each power element are disconnected, the impedance of the second voltage dividing unit is matched, and the detection value of the first voltage detector is enabled to be s 2Vdc, s 2E (0, 1/2);

then the second power element is controlled to be conducted, and after voltage balance is achieved, the obtained detection value of the first voltage detector and the theoretical voltage value V under the same detection state are obtained₂-V_NOComparing, wherein the detection values of the first voltage detector and the second voltage detector are both smaller than 1/2Vdc, if the conditions are consistent, the anti-parallel diodes on the second power element, the first diode or the second power element and the fifth power element are normal, if the conditions are different, the second power element or the first diode is in fault, or the anti-parallel diodes on the second power element or the fifth power element are in fault, and stopping detection;

8. The method of claim 7, wherein when the first diode is replaced with a fifth power device and the second diode is replaced with a sixth power device, the method further comprises the following steps after detecting the first power device:

on the basis that the anti-parallel diodes on the second power element and the fifth power element are normal, when the anti-parallel diodes on the sixth power element and the third power element are detected, the connection state of the second voltage division unit is kept, the second power element is switched off, the sixth power element is controlled to be switched on, and after voltage balance is achieved, the acquired detection value of the first voltage detector and a theoretical voltage value V under the same detection state are obtained₂-V_NOAnd comparing, wherein the detection values of the first voltage detector and the second voltage detector are both smaller than 1/2Vdc, if the conditions are consistent, the anti-parallel diodes on the sixth power element and the third power element are normal, and if the conditions are different, the anti-parallel diodes on the sixth power element or the third power element are failed, and the detection is stopped.

9. The three-level inverter power module detection method according to claim 7 or 8, wherein when the first diode is replaced with a fifth power element and the second diode is replaced with a sixth power element, the method further comprises the following steps after detecting the fourth power element:

on the basis that the anti-parallel diodes on the third power element and the sixth power element are normal, when the anti-parallel diodes on the fifth power element and the second power element are detected, the connection state of the first voltage division unit is kept, the third power element is switched off, the fifth power element is controlled to be switched on, and the acquired detection value of the first voltage detector and the theoretical voltage value V under the same detection state are obtained_NO+V₂And comparing, wherein the detection values of the first voltage detector and the second voltage detector are both larger than 1/2Vdc, if the conditions are consistent, the anti-parallel diodes on the fifth power element and the second power element are normal, and if the conditions are different, the anti-parallel diodes on the fifth power element or the second power element are failed, and the detection is stopped.

10. The three-level inverter power module detection method of claim 7, wherein: the power elements to be detected are respectively applied with pulse signals to be conducted.