JP7252149B2 - POWER CONVERTER AND FAILURE DETECTION METHOD THEREOF - Google Patents

Description

TECHNICAL FIELD Embodiments of the present invention relate to a power conversion device and a failure detection method thereof.

2. Description of the Related Art A power conversion device is known in which a plurality of power converters are connected in parallel and the plurality of power converters converts DC power to AC power or vice versa. In such a power converter, a current detector is provided at each of the AC connection points of the plurality of power converters to detect the current flowing through each of the AC connection points of the plurality of power converters. Detecting faults is done.

However, when a current detector is provided at each AC connection point of a plurality of power converters, the number of current detectors increases. For example, when each of a plurality of power converters has two AC connection points, the number of current detectors twice the number of the plurality of power converters is required, which increases the size of the power converter and increases the manufacturing cost. may become a factor in the increase in

Therefore, in the power conversion device and its failure detection method, it is possible to appropriately detect failures in a plurality of power converters connected in parallel, and to provide a current detector at each AC connection point of the plurality of power converters. It is desirable to be able to suppress an increase in the size of the device and an increase in the manufacturing cost.

Japanese Patent Application Laid-Open No. 2019-103160

Embodiments of the present invention provide a power conversion device and a failure detection method thereof that can appropriately detect failures in a plurality of power converters connected in parallel and can suppress an increase in the size of the device and an increase in manufacturing costs.

According to an embodiment of the present invention, a plurality of electrical power sources having a first AC connection point and a second AC connection point and for at least one of converting DC power to AC power and vice versa. a converter and a plurality of first wiring members connected to the first AC connection points of the plurality of power converters and connecting the first AC connection points of the plurality of power converters in parallel; and a plurality of second wiring members connected to the second AC connection points of the plurality of power converters and connecting the second AC connection points of the plurality of power converters in parallel; In a steady state, the same current flows between the first AC connection points of the plurality of power converters, and the same current flows between the second AC connection points of the plurality of power converters. , a control unit for controlling the operation of the plurality of power converters , and a plurality of current detectors provided corresponding to each of the plurality of power converters, each of the plurality of current detectors and an absolute value of a current flowing from one side of the through-hole to the other when the control unit is controlling the steady state, and a current flowing from the other side of the through-hole to one side. The first wiring member and the second wiring member connected to the same power converter are inserted into the through hole so that the difference between the absolute value of the current and the Provided is a power converter that determines that one of the plurality of power converters has failed when the absolute value of the current detected by the plurality of current detectors exceeds a predetermined value.

Provided are a power conversion device and a failure detection method thereof that can appropriately detect failures in a plurality of power converters connected in parallel and that can suppress an increase in the size of the device and an increase in manufacturing costs.

BRIEF DESCRIPTION OF THE DRAWINGS It is a block diagram which represents typically the power converter device which concerns on embodiment. It is an explanatory view showing a current detector typically. FIG. 3 is a block diagram schematically showing an example of normal operation of the power converter; FIG. 4 is a block diagram schematically showing an example of the operation of the power conversion device when there is an abnormality; It is a block diagram which represents typically the power converter device of reference. It is a block diagram which represents typically the modification of the power converter device which concerns on embodiment. It is a block diagram which represents typically the modification of the power converter device which concerns on embodiment. It is a block diagram which represents typically the modification of the power converter device which concerns on embodiment.

Each embodiment will be described below with reference to the drawings.
Note that the drawings are schematic or conceptual, and the relationship between the thickness and width of each portion, the size ratio between portions, and the like are not necessarily the same as the actual ones. Also, even when the same parts are shown, the dimensions and ratios may be different depending on the drawing.
In addition, in the present specification and each figure, the same reference numerals are given to the same elements as those described above with respect to the already-appearing figures, and detailed description thereof will be omitted as appropriate.

FIG. 1 is a block diagram schematically showing a power conversion device according to an embodiment.
As shown in FIG. 1, the power converter 2 includes a plurality of power converters 10, a plurality of first wiring members 21, a plurality of second wiring members 22, a control section 30, and a current detector 40. , provided.

The configurations of the plurality of power converters 10 are substantially the same. The power converter 10 has a first AC connection point 11a and a second AC connection point 11b. The power converter 10 also has a first DC connection point 12a and a second DC connection point 12b. The power converter 10 is connected to an AC power system, an AC load, or the like via a first AC connection point 11a and a second AC connection point 11b, and is connected to an AC power system or an AC load via a first DC connection point 12a and a second DC connection point 12b. It is connected to a DC power supply, DC load, etc. The power converter 10 performs at least one of conversion from DC power to AC power and conversion from AC power to DC power.

The power converter 10 includes, for example, four switching elements 14 that are full-bridge connected between a first DC connection point 12a and a second DC connection point 12b, a first DC connection point 12a and a second DC connection point 12b. and a charge storage element 16 (for example, a capacitor) connected in parallel with each switching element 14 between. For example, a rectifying element (for example, a diode) is connected in antiparallel to each switching element 14 . In this power converter 10, the connection points of the two switching elements 14 connected in series are the first AC connection point 11a and the second AC connection point 11b, respectively.

The power converter 10 performs at least one of conversion from DC power to AC power and conversion from AC power to DC power by switching each switching element 14 . In this example, more specifically, the power converter 10 performs at least one of conversion from DC power to single-phase AC power and conversion from single-phase AC power to DC power.

The plurality of first wiring members 21 are connected to the respective first AC connection points 11a of the plurality of power converters 10, and connect the respective first AC connection points 11a of the plurality of power converters 10 in parallel.

The plurality of second wiring members 22 are connected to the respective second AC connection points 11b of the plurality of power converters 10, and connect the respective second AC connection points 11b of the plurality of power converters 10 in parallel.

Thus, the AC sides of the plurality of power converters 10 are connected in parallel by the plurality of first wiring members 21 and the plurality of second wiring members 22 . Further, in this example, the DC sides of the plurality of power converters 10 are also connected in parallel. However, the DC sides of the plurality of power converters 10 may be connected in series.

Plate-like conductors called busbars, for example, are used for the plurality of first wiring members 21 and the plurality of second wiring members 22 . However, the plurality of first wiring members 21 and the plurality of second wiring members 22 may be cables or the like. The configuration of the plurality of first wiring members 21 and the plurality of second wiring members 22 may be any configuration that allows the AC sides of the plurality of power converters 10 to be connected in parallel.

In a steady state, the control unit 30 causes the same current to flow between the first AC connection points 11a of the plurality of power converters 10 and the same current to flow between the second AC connection points 11b of the plurality of power converters 10. The operation of the plurality of power converters 10 is controlled so that current flows. The control unit 30 controls the operation of each power converter 10 as described above, for example, by controlling switching of each switching element 14 .

In each power converter 10, the absolute value of the current flowing through the first AC connection point 11a is substantially the same as the absolute value of the current flowing through the second AC connection point 11b. In other words, the difference between the absolute value of the current flowing through the first AC connection point 11a and the absolute value of the current flowing through the second AC connection point 11b is substantially zero.

FIG. 2 is an explanatory diagram schematically showing the current detector.
As shown in FIG. 2, the current detector 40 has a through hole 40a. The shape of the current detector 40 is, for example, cylindrical. For example, a CT (Current Transformer) or the like is used for the current detector 40 . The current detector 40 may be one using a Hall element, for example. The current detector 40 may be any detector that has a through hole 40a and is capable of detecting current flowing through a conductor passing through the through hole 40a.

The current detector 40 detects the absolute value of the current flowing from one side of the through-hole 40a to the other and At least two of the plurality of first wiring members 21 and the plurality of second wiring members 22 are inserted into the through holes 40a so that the difference between the absolute value of the current and the current is zero.

The current flowing from one side of the through hole 40a to the other side is, for example, the current flowing in the direction of the arrow A in FIG. The current flowing from the other side of the through hole 40a to one side is, for example, the current flowing in the direction of the arrow B in FIG. However, the direction of current may be opposite to the above.

The power conversion device 2 includes, for example, multiple current detectors 40 . One of the plurality of current detectors 40 has the first number of first wiring members 21 that allow current to flow from one side of the through hole 40a to the other side of the through hole 40a. An even number of the first wiring members 21 are inserted through the through holes 40 a so as to be the same as the number of the wiring members 21 . Another one of the plurality of current detectors 40 has the number of second wiring members 22 that allow current to flow from one side of the through hole 40a to the other side of the through hole 40a. An even number of the second wiring members 22 are inserted through the through-holes 40 a so as to be the same as the number of the second wiring members 22 .

In this example, the power conversion device 2 includes two power converters 10 connected in parallel, two first wiring members 21 corresponding to the two power converters 10, and two second wiring members 22. and have. The power conversion device 2 includes one current detector 40 provided corresponding to the two first wiring members 21 and another current detector 40 provided corresponding to the two second wiring members 22. A total of two current detectors 40 are provided.

As shown in FIG. 2, the two first wiring members 21 are arranged such that one of them allows current to flow from one side of the through hole 40a to the other side, and the other side allows current to flow from the other side of the through hole 40a to one side. , are inserted into the through-hole 40a so that the current-flowing directions are opposite to each other. Similarly, the two second wiring members 22 allow current to flow from one side of the through-hole 40a to the other, and the other to flow the current from the other side of the through-hole 40a to one side. The direction is reversed and inserted into the through hole 40a.

Thus, in this example, the current detectors 40 are provided corresponding to the plurality of first wiring members 21 and the plurality of second wiring members 22 . In this case, the number of current detectors 40 is even. An even number of the first wiring members 21 or an even number of the second wiring members 22 are inserted through the current detector 40 . Therefore, in this example, each number of power converters 10, first wiring members 21, and second wiring members 22 is also an even number. These numbers are not limited to two, and may be any even number such as four or six. The number of power converters 10 may be an arbitrary even number according to the magnitude of power to be converted, the breakdown voltage of each switching element 14, and the like.

For example, when four power converters 10 and four first wiring members 21 are provided, two first wiring members 21 may be inserted through the through-holes 40a of the two current detectors 40, or one The four first wiring members 21 may be inserted through the through holes 40 a of the current detector 40 . Thus, the number of the first wiring members 21 or the second wiring members 22 inserted through the through-holes 40a is not limited to two, and may be any even number.

FIG. 3 is a block diagram schematically showing an example of normal operation of the power converter.
As shown in FIG. 3, when the control unit 30 is performing steady-state control, the directions of the currents flowing through the two first wiring members 21 are opposite in the through hole 40a of one of the current detectors 40. become. Similarly, when the control unit 30 is performing steady-state control, the directions of the currents flowing through the two second wiring members 22 are opposite in the through hole 40 a of the other current detector 40 .

As described above, in the steady state, the control unit 30 allows the same current to flow between the first AC connection points 11a of the plurality of power converters 10 and the second AC connection of the plurality of power converters 10 to each other. The operations of the plurality of power converters 10 are controlled such that the same current flows through the points 11b. In other words, the control unit 30 operates the power converters 10 so that the same current flows through the two first wiring members 21 and the same current flows through the two second wiring members 22 in a steady state. to control. Therefore, in the steady state, the magnetic fluxes caused by the currents flowing in the two first wiring members 21 cancel each other out, and the magnetic fluxes caused by the currents flowing in the two second wiring members 22 cancel out each other in the through hole 40a. . Therefore, in steady state, the absolute value of the current detected by the current detector 40 is substantially zero.

FIG. 4 is a block diagram schematically showing an example of the operation of the power conversion device when there is an abnormality.
4, in the four switching elements 14 of the power converter 10, the switching elements 14 on the upper arm are switching elements 14a and 14b, and the switching elements 14 on the lower arm are switching elements 14c and 14d.

FIG. 4 schematically shows a state in which the switching element 14b of the upper arm of the upper power converter 10 causes a short circuit failure when the switching element 14d of the lower arm of the two power converters 10 is turned on. represent.

As shown in FIG. 4, when the switching element 14b of the upper arm of the upper power converter 10 causes a short-circuit fault, a short-circuit current (large current) flows along the path indicated by the arrow C. Further, when the switching element 14b of the power converter 10 on the upper side causes a short-circuit failure, a detour current flows along the path indicated by the arrow D. As indicated by the arrow D, when a detour current flows, the directions of the currents flowing through the two second wiring members 22 are the same in the through hole 40 a of the current detector 40 . In this way, when any one of the switching elements 14 has a short-circuit failure, the directions of the currents flowing through the two first wiring members 21 are the same in the through hole 40 a of one of the current detectors 40 . Or, in the through hole 40a of the other current detector 40, the directions of the currents flowing through the two second wiring members 22 are the same. Therefore, when any one of the switching elements 14 has a short-circuit failure, the current detector 40 detects a current value corresponding to the current flowing through the first wiring member 21 or the second wiring member 22 .

Further, for example, when one of the switching elements 14 does not turn on due to a problem with the control signal, etc., in the steady-state operation shown in FIG. A current flows only through one first wiring member 21 in 40a. Alternatively, current flows only through one of the second wiring members 22 in the through hole 40 a of the other current detector 40 . Therefore, also in this case, the current detector 40 detects a current value corresponding to the current flowing through one of the first wiring members 21 or one of the second wiring members 22 .

The current detector 40 inputs the current value of the detected current to the controller 30 . Control unit 30 determines that one of power converters 10 has failed when the absolute value of the current detected by one of current detectors 40 is greater than or equal to a predetermined value. When determining that one of the plurality of power converters 10 has failed, the control unit 30 stops the operation of the plurality of power converters 10 . In this way, the power conversion device 2 can appropriately detect failure of any one of the plurality of power converters 10 .

A failure detection method for the power conversion device 2 includes a step of providing a current detector 40 having a through hole 40a, and a step of determining failure. In the step of providing the current detector 40, the absolute value of the current flowing from one side of the through hole 40a to the other side and the By inserting at least two of the plurality of first wiring members 21 and the plurality of second wiring members 22 into the through hole 40a so that the difference between the absolute value of the flowing current and the current detector 40 is provided. The step of determining failure is a step of determining that one of the plurality of power converters 10 has failed when the absolute value of the current detected by the current detector 40 is greater than or equal to a predetermined value.

FIG. 5 is a block diagram schematically showing a reference power converter.
As shown in FIG. 5 , in the power converter, a current detector 40 is provided at each of the first AC connection point 11 a and the second AC connection point 11 b of the plurality of power converters 10 , and the plurality of power converters 10 A configuration is also conceivable in which failures in a plurality of power converters 10 are detected by detecting currents flowing through each of the first AC connection point 11a and the second AC connection point 11b. In other words, a plurality of current detectors 40 are provided corresponding to each of the plurality of first wiring members 21 and the plurality of second wiring members 22, and the plurality of first wiring members 21 and the plurality of second wiring members 22 are provided. A configuration is also conceivable in which failures in a plurality of power converters 10 are detected by detecting the current flowing through each.

However, in the configuration shown in FIG. 5, the number of current detectors 40 increases, which may lead to an increase in the size of the power converter and an increase in manufacturing costs.

On the other hand, in the power conversion device 2 according to the present embodiment, one of the plurality of current detectors 40 allows the current to flow from one side of the through hole 40a to the other. An even number of the first wiring members 21 are inserted through the through holes 40a so as to be the same as the number of the first wiring members 21 through which the current flows from the other side to the one side of the through holes 40a. Another one of the plurality of current detectors 40 allows the current to flow from one side of the through hole 40a to the other. An even number of the second wiring members 22 are inserted through the through-holes 40a so as to be the same as the number of the second wiring members 22 to be flowed.

Thus, by providing the current detectors 40 corresponding to the plurality of first wiring members 21 and the plurality of second wiring members 22, the number of current detectors 40 can be reduced compared to the reference example shown in FIG. can do. For example, the number of current detectors 40 can be halved compared to the reference example shown in FIG. As a result, it is possible to suppress an increase in the size of the device due to the current detector 40 and an increase in the manufacturing cost. As described above, in the power conversion device 2 according to the present embodiment as well, it is possible to appropriately detect a failure in any one of the plurality of power converters 10 . Therefore, it is possible to provide a power conversion device 2 and a failure detection method thereof that can appropriately detect failures in a plurality of power converters 10 and suppress an increase in the size of the device and an increase in manufacturing costs.

In the power conversion device 2, the absolute value of the current detected by the current detector 40 is substantially zero in the steady state. Thereby, heat generation of the current detector 40 in a steady state can be suppressed as compared with the case where the current detector 40 detects a large current. For example, it is possible to prevent accelerated deterioration of the current detector 40 due to heat generation. For example, it is also possible to suppress an increase in size and cost due to the addition of a radiator for the current detector 40 .

In addition, since the absolute value of the current detected by the current detector 40 becomes substantially zero in the steady state, it is possible to use the current detector 40 with a small current, for example. For example, the current detector 40 can be made smaller and the cost of the current detector 40 can be further reduced, compared to the case of using a current detector corresponding to a large current.

FIG. 6 is a block diagram schematically showing a modification of the power converter according to the embodiment.
It should be noted that the same reference numerals are given to the parts that are substantially the same as those of the above-described embodiment in terms of function and configuration, and detailed description thereof will be omitted.
As shown in FIG. 6, the power conversion device 2a includes a plurality of current detectors 40 provided corresponding to the plurality of power converters 10, respectively. In each of the plurality of current detectors 40, the first wiring member 21 and the second wiring member 22 connected to the same power converter 10 are inserted through the through hole 40a.

Thus, the plurality of current detectors 40 may be provided corresponding to each of the plurality of power converters 10 . Also in this case, similarly to the above-described embodiment, it is possible to appropriately detect failures in a plurality of power converters 10, and to suppress an increase in the size of the device and an increase in manufacturing costs.

When the plurality of current detectors 40 are provided corresponding to each of the plurality of power converters 10, the plurality of power converters 10, the plurality of first wiring members 21, the plurality of second wiring members 22, and the plurality of current detectors Each number of units 40 may be odd.

FIG. 7 is a block diagram schematically showing a modification of the power converter according to the embodiment.
As shown in FIG. 7, in the power conversion device 2b, the numbers of the plurality of power converters 10, the plurality of first wiring members 21, and the plurality of second wiring members 22 are even numbers. In the current detector 40, each of the plurality of first wiring members 21 and the plurality of second wiring members 22 is inserted through the through hole 40a.

In this way, the number of each of the plurality of power converters 10, the plurality of first wiring members 21, and the plurality of second wiring members 22 is even, and the plurality of first wiring members 21 and the plurality of second wiring members 22 are inserted into the through-hole 40a, the absolute value of the current flowing from one side of the through-hole 40a to the other and the current flowing from the other side of the through-hole 40a to the one The difference between the absolute value of the current flowing toward and may be zero.

Also in this case, similarly to the above-described embodiment, it is possible to appropriately detect failures in a plurality of power converters 10, and to suppress an increase in the size of the device and an increase in manufacturing costs. When each of the plurality of first wiring members 21 and the plurality of second wiring members 22 is inserted through the through hole 40a, only one current detector 40 is required, and the number of parts of the power conversion device 2b is further reduced. can do.

The difference between the absolute value of the current flowing from one side of the through-hole 40a to the other side and the absolute value of the current flowing from the other side of the through-hole 40a to one side when the control unit 30 is performing steady-state control. The wiring method of the first wiring member 21 and the second wiring member 22, the number of the current detectors 40, etc., which make the . An appropriate selection may be made in consideration of ease of application.

FIG. 8 is a block diagram schematically showing a modification of the power converter according to the embodiment.
As shown in FIG. 8, in the power converter 2c, the power converter 10 has six switching elements 14 that are three-phase bridge-connected between the first DC connection point 12a and the second DC connection point 12b. In addition, it further has a third AC connection point 11c. In power converter 2c, power converter 10 performs at least one of conversion from DC power to three-phase AC power and conversion from three-phase AC power to DC power.

Moreover, the power conversion device 2 c further includes a plurality of third wiring members 23 . The plurality of third wiring members 23 are connected to the respective third AC connection points 11c of the plurality of power converters 10, and connect the respective third AC connection points 11c of the plurality of power converters 10 in parallel.

In the power conversion device 2c, the number of the third wiring members 23 through which one of the plurality of current detectors 40 flows a current from one side of the through hole 40a to the other side is An even number of the third wiring members 23 are inserted through the through holes 40a so as to be the same as the number of the third wiring members 23 through which current flows.

As a result, even in the power conversion device 2c having a three-phase configuration, as in the above embodiment, it is possible to appropriately detect failures in a plurality of power converters 10, suppress the number of current detectors 40, and increase the size of the device. It is possible to suppress the increase in the reduction and manufacturing cost.

Thus, the AC power converted by the power converter 10 is not limited to single-phase AC power, and may be three-phase AC power or the like. Moreover, the configuration of the power converter 10 is not limited to a single-phase bridge circuit or a three-phase bridge circuit. Power converter 10 may be, for example, a multi-level converter such as a three-level inverter. The configuration of the power converter 10 allows the same current to flow through the plurality of first AC connection points 11a, the plurality of second AC connection points 11b, and the plurality of third AC connection points 11c in a steady state. Any configuration is acceptable.

While several embodiments of the invention have been described, these embodiments have been presented by way of example and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and modifications can be made without departing from the scope of the invention. These embodiments and their modifications are included in the scope and gist of the invention, and are included in the scope of the invention described in the claims and equivalents thereof.

2, 2a, 2b, 2c power converter, 10 power converter, 11a first AC connection point, 11b second AC connection point, 11c third AC connection point, 12a first DC connection point, 12b second DC connection point , 14 switching element, 16 charge storage element, 21 first wiring member, 22 second wiring member, 23 third wiring member, 30 control unit, 40 current detector, 40a through hole

Claims (2)

a plurality of power converters having a first AC connection point and a second AC connection point and performing at least one of DC power to AC power conversion and AC power to DC power conversion;
a plurality of first wiring members connected to the first AC connection points of the plurality of power converters and connecting the first AC connection points of the plurality of power converters in parallel;
a plurality of second wiring members connected to the second AC connection points of the plurality of power converters and connecting the second AC connection points of the plurality of power converters in parallel;
In a steady state, the same current flows between the first AC connection points of the plurality of power converters, and the same current flows between the second AC connection points of the plurality of power converters. , a control unit that controls the operation of the plurality of power converters;
a plurality of current detectors provided corresponding to each of the plurality of power converters;
with
Each of the plurality of current detectors has a through hole, and when the control unit is controlling the steady state, the absolute value of the current flowing from one side of the through hole to the other The first wiring member and the second wiring member connected to the same power converter are inserted into the through hole so that the difference between the absolute value of the current flowing from the other side to the one side of the hole becomes zero. through,
The power conversion device, wherein the control unit determines that one of the plurality of power converters has failed when an absolute value of the current detected by the plurality of current detectors is equal to or greater than a predetermined value. a plurality of power converters having a first AC connection point and a second AC connection point and performing at least one of DC power to AC power conversion and AC power to DC power conversion;
a plurality of first wiring members connected to the first AC connection points of the plurality of power converters and connecting the first AC connection points of the plurality of power converters in parallel;
a plurality of second wiring members connected to the second AC connection points of the plurality of power converters and connecting the second AC connection points of the plurality of power converters in parallel;
In a steady state, the same current flows between the first AC connection points of the plurality of power converters, and the same current flows between the second AC connection points of the plurality of power converters. , a control unit that controls the operation of the plurality of power converters;
In a failure detection method for a power conversion device comprising
A step of providing a plurality of current detectors having through-holes corresponding to each of the plurality of power converters , wherein when the control unit is controlling the steady state, one of the through-holes to the other The first wiring member connected to the same power converter such that the difference between the absolute value of the current flowing toward the through hole and the absolute value of the current flowing from the other side of the through hole toward the one side is zero. a step of providing the plurality of current detectors corresponding to each of the plurality of power converters by inserting the second wiring member and the second wiring member through the through holes;
determining that one of the plurality of power converters has failed when the absolute value of the current detected by the plurality of current detectors exceeds a predetermined value;
A failure detection method for a power conversion device having

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