Devices and power converters
Patent Information
- Authority / Receiving Office
- JP · JP
- Patent Type
- Patents
- Current Assignee / Owner
- FUJI ELECTRIC CO LTD
- Filing Date
- 2022-06-09
- Publication Date
- 2026-08-04
Smart Images
Figure 0007899593000001 
Figure 0007899593000002 
Figure 0007899593000003
Abstract
Description
[Technical Field]
[0001] The present invention relates to a device and a power conversion device. [Background technology]
[0002] Conventionally, power converters and the like have multiple semiconductor elements connected in parallel (see, for example, Patent Document 1). Patent Document 1: Japanese Unexamined Patent Publication No. 2020-14295 [Overview of the Initiative] [Problems that the invention aims to solve]
[0003] If the current between parallel-connected elements becomes unbalanced due to failures or variations in characteristics, there is a risk that the current will concentrate on one of the elements, potentially causing element failure. [Means for solving the problem]
[0004] To solve the above problems, a first embodiment of the present invention provides an apparatus. The apparatus may include a sensor that measures a parameter corresponding to the difference in current flow between a current path that branches off from a common current path and passes through one semiconductor element among a plurality of parallel-connected semiconductor elements, and a current path that passes through another semiconductor element, and a detection unit that detects an abnormality when the parameter measured by the sensor falls outside a reference range.
[0005] In the above-described apparatus, the sensor may measure the parameter corresponding to the total current of an antiparallel portion arranged such that current flows in opposite directions between a current path branching from the common current path and passing through one semiconductor element and a current path passing through the other semiconductor element.
[0006] In any of the above-described devices, the sensor may be a magnetic sensor.
[0007] The sensor may have a Rogowski coil.
[0008] Any of the above devices may include a plurality of the sensors. Each of the plurality of sensors may measure the parameter corresponding to the difference in current flowing through a pair of different current paths, which are among a plurality of current paths that branch off from the common current path and pass through each of the plurality of semiconductor elements.
[0009] In the above-described apparatus comprising a plurality of sensors, the number of the plurality of sensors may be less than the number of the plurality of semiconductor elements.
[0010] In any of the above-described devices equipped with a plurality of sensors, the plurality of sensors may measure the parameter corresponding to the difference in current flowing through a current path passing through one semiconductor element and a current path passing through each semiconductor element other than the one semiconductor element.
[0011] In any of the above-described devices equipped with a plurality of the sensors, the plurality of semiconductor elements may have n semiconductor elements (where n is an integer of 2 or more). The plurality of sensors may measure the parameter corresponding to the difference in current flow between the current path passing through the Nth semiconductor element (where N is an integer of 1 ≤ N ≤ n-1) and the current path passing through the N+1th semiconductor element.
[0012] In any of the above-described devices comprising a plurality of sensors, the plurality of sensors may each have at least one sensor that measures the parameter corresponding to the difference in current flowing through at least one pair of current paths that branch off from the common current path and lead to two or more equal numbers of semiconductor elements among the plurality of semiconductor elements.
[0013] In any of the above-described devices equipped with multiple sensors, the detection unit may detect that an abnormality has occurred when the parameter measured by at least one of the sensors falls outside the reference range.
[0014] In any of the above-described devices, the detection unit may detect whether the parameter measured by the sensor falls outside the reference range at a time when a reference time has elapsed from the input timing of the turn-on signal to the plurality of semiconductor elements.
[0015] Any of the above-described devices may further include a cutoff control unit that cuts off the current flowing through the plurality of semiconductor elements in response to the detection unit detecting that an abnormality has occurred.
[0016] In any of the above-described devices, each semiconductor element may be a switching element.
[0017] The above-described device may further include a drive unit that drives the control terminals of each switching element in accordance with the input drive signal.
[0018] In a second embodiment of the present invention, a power conversion device is provided. The power conversion device may comprise a plurality of semiconductor elements, each of which is a switching element, and the above-described device.
[0019] In the power conversion device described above, each semiconductor element may be a wide-bandgap semiconductor element.
[0020] It should be noted that the above summary of the invention does not enumerate all the necessary features of the present invention. Furthermore, subcombinations of these features may also constitute an invention. [Brief explanation of the drawing]
[0021] [Figure 1] A power conversion device 1 according to the first embodiment is shown. [Figure 2] This shows the operating waveform of power converter 1 under normal conditions. [Figure 3] This shows the operating waveform of power converter 1 when an abnormality occurs. [Figure 4] This shows other operating waveforms of power converter 1 in the event of an abnormality. [Figure 5]A power converter 1A according to the second embodiment is shown. [Figure 6] This shows the operating waveform of power converter 1A under normal conditions. [Figure 7] This shows the operating waveform of power converter 1A when an abnormality occurs. [Figure 8] This shows other operating waveforms of power converter 1A in the event of an abnormality. [Figure 9] This shows other operating waveforms of power converter 1A in the event of an abnormality. [Figure 10] A power converter 1B according to a modified example (1) of the second embodiment is shown. [Figure 11] A power converter 1C according to a modified example (2) of the second embodiment is shown. [Modes for carrying out the invention]
[0022] The present invention will be described below through embodiments of the invention, but these embodiments are not intended to limit the invention as defined in the claims. Furthermore, not all combinations of features described in the embodiments are necessarily essential to the solution of the invention.
[0023] [1. First Embodiment] Figure 1 shows a power converter 1 according to the first embodiment. In the figure, white arrows indicate voltage, and black arrows indicate current.
[0024] [1.1. Power converter 1] The power converter 1 shows, as an example, one phase of a power converter used for motor driving or power supply. By switching the connection between the positive power line 101 and the negative power line 102 and the power output terminal 105, it outputs a converted voltage from the power output terminal 105. A DC voltage of several thousand to several hundred volts may be applied between the positive power line 101 and the negative power line 102.
[0025] The power converter 1 has two switching elements 11,... connected in parallel, and two switching elements 12,... (switching element 12 (1) , 12 (2) The system comprises a drive unit 2 associated with each switching element 11,... and a drive unit 5 associated with each switching element 12,... (also known as a drive unit 2).
[0026] Each switching element 11, ... and each switching element 12, ... are elements that can be switched on / off by the drive unit 2 and the drive unit 5, respectively. In this embodiment, as an example, the multiple switching elements 11 and the multiple switching elements 12 are each MOSFETs and have a parasitic diode whose cathode is on the side of the positive power supply line 101. Note that the multiple switching elements 11 and the multiple switching elements 12 can also be semiconductor elements of other structures, such as IGBTs or bipolar transistors, and diodes, Schottky barrier diodes, etc. can be connected in antiparallel to each semiconductor element as needed.
[0027] At least one of the multiple switching elements 11 and the multiple switching elements 12 may be a wide-bandgap semiconductor element. A wide-bandgap semiconductor element is a semiconductor element with a larger bandgap than a silicon semiconductor element, and includes, for example, semiconductor elements such as SiC, GaN, diamond, gallium nitride-based materials, gallium oxide-based materials, AlN, AlGaN, or ZnO. Wide-bandgap semiconductor elements can improve the switching speed compared to silicon semiconductor elements.
[0028] Each switching element 11,... may constitute the upper arm of the power converter 1, and each switching element 12,... may constitute the lower arm of the power converter 1. Two switching elements 11,... and two switching elements 12,... may be connected in series sequentially between the positive power line 101 and the negative power line 102. A power output terminal 105 may be connected to the midpoint between two switching elements 11,... and two switching elements 12,....
[0029] Each switching element 11,... may be provided in two parallel current paths 1011,... branched from a common current path. In this embodiment, as an example, the two current paths 1011,... may branch from the positive power line 101 toward the downstream side (negative electrode side) of the current from the upstream side (positive electrode side). Also, the two current paths 1011,... may branch from the current path for output connected to the power output terminal 105 toward the upstream side of the current from the downstream side. The current flowing through each branched current path 1011 may be the element current of the switching element 11 provided in the current path 1011.
[0030] The two current paths 1011,... may have an antiparallel portion 510 arranged to flow currents in opposite directions to each other. The current paths 1011 of the antiparallel portion 510 may be arranged in reverse parallel to each other. The current paths 1011 of the antiparallel portion 510 may act differentially to cancel out magnetic fields.
[0031] Each switching element 12,... may be provided in two parallel current paths 1021,... branched from a common current path. In this embodiment, as an example, the two current paths 1021,... may branch from the current path for output connected to the power output terminal 105 toward the downstream side (negative electrode side) of the current from the upstream side (positive electrode side). Also, the two current paths 1021,... may branch from the negative power line 102 toward the upstream side of the current from the downstream side. As a result, the current Id flowing through the common current path is divided into the current Id1 flowing through the current path 1021 (also referred to as the current path 1021) through which the switching element 12 (1) passes, and the current Id2 flowing through the current path 1021 (also referred to as the current path 1021) through which the switching element 12 (1) passes. The current flowing through each branched current path 1021 (2) , 1021 (2) may be the current flowing through the current path 1021 (1) , 1021 (2) provided with the switching element 12 (1) , 1021 (2) provided in the current path 1021 (1) , 12 (2)It may be the element current.
[0032] Two current paths 1021 (1) ,1021 (2) It may have antiparallel sections 510 arranged so that current flows in opposite directions from each other. The current paths 1021 of the antiparallel sections 510 may be arranged antiparallel to each other. The current paths 1021 of the antiparallel sections 510 may be arranged adjacent to each other so that they act differentially and cancel out the magnetic field.
[0033] Here, if current concentrates in some current paths 1011 due to a failure or variation in the characteristics of the switching element 11 (for example, temperature characteristics, switching speed, gate voltage threshold, etc.), element damage due to overcurrent may occur. Similarly, if current concentrates in some current paths 1021 due to a failure or variation in the characteristics of the switching element 12, element damage due to overcurrent may occur. Therefore, in the power converter 1 according to this embodiment, the drive unit 2 detects the occurrence of an abnormality when the element currents of each parallel-connected switching element 11 become unbalanced, and the drive unit 5 detects the occurrence of an abnormality when the element currents of each parallel-connected switching element 12 become unbalanced. Note that the configuration of the drive unit 2 is the same as that of the drive unit 5, so the explanation is omitted and the illustration is simplified.
[0034] The drive device 5 may be an example of a device and includes a drive unit 50, a sensor 51, a detection unit 52, and a cutoff control unit 55. Note that each part of the drive device 5 may be mounted on a gate drive unit (GDU) substrate (not shown).
[0035] The drive unit 50 drives the control terminals (gate terminals, for example, in this embodiment) of each switching element 12 according to the input drive signal S1. In this embodiment, for example, the drive unit 50 may turn on each switching element 12 when the drive signal S1 is high level, and turn off each switching element 12 when the drive signal S1 is low level. The drive unit 50 may cooperate with the drive unit (not shown) of the drive device 2 to alternately turn on multiple switching elements 11 and multiple switching elements 12, by turning off one element to switch it to the off state, and then turning on the other element. The drive unit 50 may be connected to the gate terminal of each switching element 12. The drive signal S1 may be input to the drive unit 50 from the cutoff control unit 55, which will be described later.
[0036] Sensor 51 branches off from a common current path to switch element 12 (1) The current path 1021 passes through, and the switching element 12 (2) A parameter corresponding to the difference between currents Id1 and Id2 flowing through the current path 1021 is measured. The measured parameter (also called the measurement parameter) may indicate the degree of imbalance between current Id1 and current Id2.
[0037] Sensor 51 is located in the current path 1021 (1) And, current path 1021 (2) Parameters corresponding to the total current of the antiparallel section 510, which is arranged so that current flows in opposite directions between it and the current path 1021, may be measured. (1) ,1021 (2) The total current in the antiparallel section 510 is the current path 1021 in the antiparallel section 510. (1) The current and the current path 1021 in the antiparallel section 510 (2) It may be the combined current of the two currents.
[0038] Sensor 51 may be a magnetic sensor and may measure parameters corresponding to the magnetism generated by the total current flowing through the antiparallel section 510. In this embodiment, as an example, sensor 51 may have a Rogowski coil. The Rogowski coil may be provided so as to surround the current paths 1021 of the antiparallel section 510 and may generate an induced voltage Vm across its ends corresponding to the magnetism generated by the total current in the antiparallel section 510. Sensor 51 may measure the induced voltage Vm generated in the Rogowski coil as a measurement parameter. The measured induced voltage Vm may represent the derivative of the total current in the antiparallel section 510, i.e., the rate of change over time. Current path 1021 (1) The rate of change of current over time and current path 1021 (2) If the time rate of change of the current is equal to the measurement parameter, the measurement parameter may be zero. Sensor 51 may supply the measurement result to detection unit 52.
[0039] The detection unit 52 detects an abnormality when the measurement parameters from the sensor 51 fall outside the reference range. This detects the occurrence of an abnormality when the element currents Id1 and Id2 become unbalanced compared to the reference.
[0040] The reference range can be set arbitrarily, for example, the switching element 12 (1) ,12 (2) The range may be within an allowable limit for the difference between the element currents Id1 and Id2. The detection unit 52 may have a determination unit 520 that determines whether the measurement parameter is within the reference range, and may detect that an abnormality has occurred when the determination unit 520 determines that the measurement parameter is outside the reference range. The determination unit 520 may be a comparator that compares the measurement parameter with the upper and lower limits of the reference range.
[0041] The detection unit 52 may detect whether the measurement parameters fall outside the reference range at a time when a reference time has elapsed from the input timing of the turn-on signal to the multiple switching elements 12. The reference time may be longer than or equal to the time from the input timing of the turn-on signal until the switching elements 12 enter a steady-state ON state. In this case, detection is performed in the steady-state ON state of the switching elements 12. Alternatively, the reference time may be shorter than the time from the input timing of the turn-on signal until the switching elements 12 enter a steady-state ON state. In this case, detection is performed in the transient state of the switching elements 12.
[0042] The detection unit 52 may supply a detection signal S2 indicating the detection result to the cutoff control unit 55 and to an external device of the drive unit 5 (for example, the control device described in the power converter 1). In this embodiment, for example, a high level of the detection signal S2 may indicate that an abnormality has occurred, and a low level may indicate that no abnormality has occurred.
[0043] The interruption control unit 55 interrupts the current flowing through the multiple switching elements 12 in response to the detection of an abnormality. The interruption control unit 55 may also turn off each switching element 12 in response to the detection of an abnormality.
[0044] The interruption control unit 55 may include a NOT gate 550 and an AND gate 551. The NOT gate 550 may be provided between the detection unit 52 and the AND gate 551, and may supply the AND gate 551 with a signal obtained by inverting the detection signal S2 output from the detection unit 52. The signal output from the NOT gate 550 may be an interruption signal S3 indicating whether or not the current flowing through each switching element 12 should be interrupted. In this embodiment, as an example, the interruption signal S3 may indicate that the current should not be interrupted when it is high level, and that the current should be interrupted when it is low level.
[0045] The AND gate 551 may be provided between the control device of the power converter 1 and the drive unit 50. The AND gate 551 may take a logical AND operation between the control signal S4 of the switching element 12 supplied from the control device and the cutoff signal S3 supplied from the NOT gate 550. The AND gate 551 may supply a drive signal S1 to the drive unit 50 according to the result of the logical AND operation.
[0046] As a result, if the detection unit 52 detects that an abnormality has occurred, a low-level drive signal S1 may be supplied to the drive unit 50 regardless of the signal level of the control signal S4 from the control device, thereby interrupting the current flowing through each switching element 12.
[0047] If the detection unit 52 has not detected an abnormality, a drive signal S1 with a signal level corresponding to the control signal S4 from the control device may be supplied to the drive unit 50. In this embodiment, as an example, if the control signal S4 is at a high level, a high-level drive signal S1 may be supplied to the drive unit 50, and if the control signal S4 is at a low level, a low-level drive signal S1 may be supplied to the drive unit 50.
[0048] According to the power conversion device 1 described above, the switching element 12 branches off from the common current path 1021. (1) Current path 1021 passing through (1) and switching element 12 (2) Current path 1021 passing through (2)An abnormality is detected when a measurement parameter corresponding to the difference between the currents Id1 and Id2 flowing through the two switches falls outside the reference range. Therefore, an abnormality is detected when the element current becomes unbalanced between two parallel-connected switching elements 12,… This allows for reliable detection of abnormalities in the element currents flowing through each of the two switching elements 12,… using a single sensor 51. Thus, the circuit configuration for detecting abnormalities can be simplified compared to the case where a sensor 51 is provided for each of the two switching elements 12,… in order to individually measure the element current. Furthermore, since abnormalities are detected using a measurement parameter corresponding to the difference between the currents Id1 and Id2, an abnormality is detected according to the difference between the normally fluctuating element current and the abnormal element current. Therefore, if the difference between the normally fluctuating element current and the abnormal element current becomes large early on, an abnormality can be detected quickly.
[0049] Also, switching element 12 (1) Current path 1021 passing through (1) and switching element 12 (2) Current path 1021 passing through (2) The sensor 51 measures a measurement parameter corresponding to the total current in the antiparallel section 510, which is arranged so that currents flow in opposite directions between the two components. Therefore, since it is possible to measure a parameter corresponding to the magnetic field that is canceled out by the currents flowing through the antiparallel section as a parameter corresponding to the total current in the antiparallel section 510, a magnetic sensor can be used as the sensor 51.
[0050] Furthermore, since sensor 51 is a magnetic sensor, the current path 1021 (1) ,1021 (2) A parameter corresponding to the difference in current flowing through the current path 1021 (1) ,1021 (2) Measurement can be taken while electrically insulated from it. Therefore, current path 1021 (1) ,1021 (2)This eliminates the need for a configuration that shifts the potential of the measurement signal using an isolation circuit or the like depending on the potential. Furthermore, because the delay caused by shifting the potential is eliminated, the measurement signal can be transmitted quickly, allowing for rapid detection of abnormalities.
[0051] Furthermore, since the sensor 51 has a Rogowski coil, the drive unit 5 can be made smaller compared to cases where other sensors with a core are used. In addition, because the rate of change of current over time can be measured, abnormalities in the element current can be reliably detected regardless of the magnitude of the current.
[0052] Furthermore, it is detected whether the measurement parameters fall outside the reference range at a reference time elapsed from the input timing of the turn-on signals to the multiple switching elements 12. Therefore, the presence or absence of an abnormality can be detected at the timing when an abnormality is certain to occur.
[0053] Furthermore, since the current flowing through the multiple switching elements 12 is interrupted when an abnormality is detected, it is possible to prevent each switching element 12 from remaining in the ON state in an abnormal condition.
[0054] [1.2. Operation] Figure 2 shows the operating waveform of the power converter 1 under normal conditions. In this figure, and in Figures 3 and 4 described later, the horizontal axis represents time, and the vertical axis represents the current Id flowing through the common current path, element currents Id1 and Id2, the induced voltage Vm measured by the sensor 51, the detection signal S2 from the detection unit 52, and the cutoff signal S3 from the cutoff control unit 55.
[0055] At time t10, when the control signal S4 becomes high and each switching element 12 is turned on, the current Id in the common current path and the switching element 12 (1) ,12 (2)The element currents Id1 and Id2 each increase. In this example of operation, the induced voltage Vm generated according to the difference between element currents Id1 and Id2 is within the reference range, so the detection signal S2 is maintained at a low level and the cutoff signal S3 is maintained at a high level. Then, at time t15, the control signal S4 becomes low, each switching element 12 is turned off, and the currents Id, Id1, and Id2 become 0.
[0056] Figure 3 shows the operating waveform of the power converter 1 when an abnormality occurs. At time t20, the control signal S4 becomes high level and each switching element 12 is turned on, and the current Id in the common current path and the switching element 12 (1) The element current Id1 and the element current Id1 increase. In this example of operation, the switching element 12 (2) As a result of the failure, the element current Id2 does not rise, and the induced voltage Vm generated according to the difference between element currents Id1 and Id2 falls outside the reference range. Consequently, at time t21, after the reference time has elapsed from time t20, the detection unit 52 detects that an abnormality has occurred, and the detection signal S2 becomes high level. Then, at time t22, the cutoff signal S3 becomes low level, and as a result, at time t25, the current flowing through each switching element 12 is cut off.
[0057] Figure 4 shows other operating waveforms of the power converter 1 when an abnormality occurs. At time t30, the control signal S4 becomes high level and each switching element 12 is turned on, and the current Id in the common current path and the switching element 12 (2) The element current Id2 and the element current Id2 increase. In this example of operation, the switching element 12 (1) As a result of the failure, the element current Id1 does not rise, and the induced voltage Vm generated according to the difference between element currents Id1 and Id2 falls outside the reference range. Consequently, at time t31, after the reference time has elapsed from time t30, the detection unit 52 detects that an abnormality has occurred, and the detection signal S2 becomes high level. Then, at time t32, the cutoff signal S3 becomes low level, and as a result, at time t35, the current flowing through each switching element 12 is cut off.
[0058] [2. Second Embodiment] Figure 5 shows a power converter 1A according to the second embodiment. In this embodiment and the modified examples described later, the configuration of the upper arm is the same as that of the lower arm, so its description and illustration are omitted. Also, components that are substantially the same as those in the power converter 1 shown in Figure 1 are given the same reference numerals, and their descriptions are omitted.
[0059] [2.1. Power converter 1A] The power converter 1A has three or more (three as an example in this embodiment) switching elements 12, ... (switching element 12 (1), 12 (2) ,12 (3) It comprises a drive unit 5A associated with each switching element 12, ... (also known as a switch element 12, ...).
[0060] Each switching element 12,... may be provided on a plurality of parallel current paths 1021A,... (in this embodiment, three as an example) branching off from a common current path. The common current path may be an output current path connected to the power output terminal 105, or it may be a negative power line 102. The current Id flowing through the common current path is the current of the switching element 12 (1) Current path 1021A (current path 1021A (1) The current Id1 flowing through (also called) and the switching element 12 (2) Current path 1021A (current path 1021A (2) The current Id2 flowing through (also called) and the switching element 12 (3) Current path 1021A (current path 1021A (3) The current Id3 flowing through (also known as) may be split into two.
[0061] Each current path 1021A, ... may have an antiparallel section 510 arranged to allow current to flow in opposite directions from other current paths 1021A. The antiparallel section 510 may be provided between a current path 1021A that passes through one of the multiple current paths 1021A and each current path 1021A that passes through a different switching element 12. In this embodiment, as an example, the antiparallel section 510 is located in the current path 1021A (1) and current path 1021A (2) It is provided between them, and current path 1021A (1) and current path 1021A (3) They may be provided in between. The current paths 1021A of the antiparallel section 510 may be arranged antiparallel to each other. The current paths 1021A of the antiparallel section 510 may be arranged adjacent to each other so that they act differentially and cancel out the magnetic fields.
[0062] The drive unit 5A includes a plurality of sensors 51A, a detection unit 52A, and a cutoff control unit 55. The number of the plurality of sensors 51A may be less than the number of the plurality of switching elements 12. In this embodiment, as an example, the number of the plurality of sensors 51A may be 2, and the number of the plurality of switching elements 12 may be 3.
[0063] Each sensor 51A may be the same type of sensor as sensor 51 in the first embodiment. Each of the multiple sensors 51A may measure a parameter corresponding to the difference in current flowing through a pair of different current paths 1021A, 1021A from among multiple current paths 1021A that branch off from a common current path and pass through each of the multiple switching elements 12. For example, the multiple sensors 51A may measure a parameter corresponding to the difference in current flowing through a current path 1021A that passes through one of the multiple current paths 1021A that pass through each of the other switching elements 12. In this embodiment, as an example, one of the two sensors 51A (sensor 51A (1) (Also known as) is a switching element 12 (1) Current path 1021A (1)And other switching elements 12 (2) Current path 1021A (2) The induced voltage Vm1 corresponding to the total current flowing through the antiparallel section 510 may be measured. The other sensor 51A (sensor 51A (2) (Also known as) is a switching element 12 (1) Current path 1021A (1) And other switching elements 12 (3) Current path 1021A (3) The induced voltage Vm2 corresponding to the total current flowing through the antiparallel section 510 may be measured.
[0064] The detection unit 52A detects an abnormality when the measurement parameter from at least one sensor 51A falls outside the reference range. The reference range can be set arbitrarily, for example, the switching element 12 (1) ,12 (2) The range may be within the allowable limit for the difference in element current between the two elements. The detection unit 52A may have a plurality of determination units 520 (two in this embodiment as an example) and an OR gate 521.
[0065] Each determination unit 520 may correspond one-to-one with a sensor 51A and may determine whether the measurement parameter from the corresponding sensor 51A is within the reference range. Each determination unit 520 may supply a signal indicating the determination result (also referred to as the determination signal S5) to the OR gate 521. In this embodiment, as an example, sensor 51A (1) The corresponding determination unit 520 (determination unit 520 (1) (Also known as) is the determination signal S5 (1) The OR gate 521 may be supplied to the sensor 51A. (2) The corresponding determination unit 520 (determination unit 520 (2) (Also known as) is the determination signal S5 (2) The OR gate 521 may be supplied with the OR signal S5. The determination signal S5 may indicate that the measurement parameter is outside the reference range when it is high, and may indicate that the measurement parameter is within the reference range when it is low.
[0066] The OR gate 521 may take the logical OR of the determination signals S5 from each determination unit 520. The OR gate 521 may supply a detection signal S2 corresponding to the result of the logical OR operation to the cutoff control unit 55 and to an external device of the drive unit 5A (for example, the control device of the power converter 1A).
[0067] Furthermore, the detection unit 52A described above may detect whether the measurement parameter falls outside the reference range at a timing when a reference time has elapsed from the input timing of the turn-on signal to the multiple switching elements 12, similar to the detection unit 52 described above.
[0068] With the power conversion device 1A described above, parameters corresponding to the difference in current flowing through pairs of different current paths 1021A, 1021A, among the multiple current paths 1021A, ... that branch off from a common current path and pass through each of the multiple switching elements 12, are measured by each of the multiple sensors 51A. Therefore, if the element current flowing through each pair of switching elements 12 arranged in each pair of current paths 1021 becomes unbalanced, an abnormality can be detected. Thus, abnormalities in the element current flowing through each pair of switching elements 12 can be reliably detected.
[0069] Also, among the multiple switching elements 12, one switching element 12 (1) The current path 1021A passes through, and each other switching element 12 (2) Parameters corresponding to the difference in current flowing through the current path 1021A, ... are measured by multiple sensors 51A. Therefore, one switching element 12 (1) and each of the other switching elements 12 (2) If the element currents flowing through , ... become unbalanced, an abnormality can be detected in each case.
[0070] In addition, since it is detected that an abnormality has occurred in response to the parameter measured by at least one sensor 51A being outside the reference range, compared with the case where an abnormality is detected in response to all the parameters measured by each sensor 51A being outside the reference range, the abnormality can be surely detected.
[0071] Further, since the number of sensors 51A is less than the number of switching elements 12, the circuit configuration can be simplified compared with the case where a sensor 51A is provided for each switching element 12.
[0072] [2.2. Operation] FIG. 6 shows the operation waveforms of the power conversion device 1A in a normal case. In this figure and FIGS. 7 to 9 described later, the horizontal axis represents time, and the vertical axis represents the current Id flowing through the common current path, the element currents Id1, Id2, Id3, the sensors 51A (1) , 51A (2) the induced voltages Vm1, Vm2 measured by, the determination unit 520 (1) , 520 (2) the determination signal S5 from (1) , S5 (2) , the detection signal S2 from the detection unit 52, and the cutoff signal S3 in the cutoff control unit 55.
[0073] When the control signal S4 becomes high level at time t40 and each switching element 12 is turned on, the current Id in the common current path and the switching element 12 (1) , 12 (2) , 12 (3) the element currents Id1, Id2, Id3 of each increase. In this operation example, since the induced voltage Vm1 generated according to the difference between the element currents Id1, Id2 is within the reference range, the determination signal S5 (1) is maintained at the low level. Also, since the induced voltage Vm2 generated according to the difference between the element currents Id1, Id3 is within the reference range, the determination signal S5 (2)is maintained at a low level. As a result, the detection signal S2 is maintained at a low level and the cutoff signal S3 is maintained at a high level. Then, at time t45, the control signal S4 becomes a low level and each switching element 12 is turned off, and the currents Id, Id1, Id2, and Id3 become 0.
[0074] FIG. 7 shows the operation waveforms of the power conversion device 1A when an abnormality occurs. When the control signal S4 becomes a high level at time t50 and each switching element 12 is turned on, the current Id in the common current path, the element current Id1 of the switching element 12 (1) and the element current Id2 of the switching element 12 (2) each increase. In this operation example, as a result of the switching element 12 (3) malfunctioning, the element current Id3 does not increase, so the induced voltage Vm2 generated according to the difference between the element currents Id1 and Id3 is outside the reference range. As a result, at time t51 after the reference time has elapsed from time t50, the detection unit 52 detects that an abnormality has occurred, and the determination signal S5 (2) and the detection signal S2 become high levels. Then, as a result of the cutoff signal S3 becoming a low level at time t52, at time t55, the current flowing through each switching element 12 is cut off.
[0075] FIG. 8 shows other operation waveforms of the power conversion device 1A when an abnormality occurs. When the control signal S4 becomes a high level at time t60 and each switching element 12 is turned on, the current Id in the common current path, the element current Id2 of the switching element 12 (2) and the element current Id3 of the switching element 12 (3) each increase. In this operation example, as a result of the switching element 12 (1) malfunctioning, the element current Id1 does not increase, so the induced voltage Vm1 generated according to the difference between the element currents Id1 and Id2 and the induced voltage Vm2 generated according to the difference between the element currents Id1 and Id3 are outside the reference range. As a result, at time t61 after the reference time has elapsed from time t60, the detection unit 52 detects that an abnormality has occurred, and the determination signal S5 (1) , S5 (2)The detection signal S2 becomes high level. Then, at time t62, the cutoff signal S3 becomes low level, and as a result, at time t65, the current flowing through each switching element 12 is cut off.
[0076] Figure 9 shows other operating waveforms of the power converter 1A when an abnormality occurs. At time t70, the control signal S4 becomes high level and each switching element 12 is turned on, and the current Id in the common current path and the switching element 12 (1) The element current Id1 and the element current Id1 increase. In this example of operation, the switching element 12 (2) and switching elements 12 (3) As a result of the failure of the element, the element currents Id2 and Id3 do not rise, so the induced voltage Vm1 generated according to the difference between element currents Id1 and Id2, and the induced voltage Vm2 generated according to the difference between element currents Id1 and Id3, fall outside the reference range. As a result, at time t71, after the reference time has elapsed from time t70, the detection unit 52 detects that an abnormality has occurred and the judgment signal S5 is issued. (1) S5 (2) The detection signal S2 becomes high level. Then, at time t72, the cutoff signal S3 becomes low level, and as a result, at time t75, the current flowing through each switching element 12 is cut off.
[0077] [2.3. Modified Examples of the Second Embodiment] [2.3.1. Modification of the second embodiment (1)] Figure 10 shows a power converter 1B according to a modified example (1) of the second embodiment.
[0078] The power converter 1B has n switching elements 12, ... (where n is an integer of 2 or more, and in this embodiment, 3 as an example) connected in parallel. (1) ,12 (2) ,12 (3) It comprises a drive unit 5B associated with each switching element 12, ... (also known as a switch unit 12, ...).
[0079] Each switching element 12,... may be provided in a plurality of parallel current paths 1021B,... branching off from a common current path. The common current path may be an output current path connected to the power output terminal 105, or it may be a negative power line 102. The current flowing through the common current path is supplied to the switching element 12 (1) Current path 1021B (current path 1021B (1) The current Id1 flowing through (also called) and the switching element 12 (2) Current path 1021B (current path 1021B (2) The current Id2 flowing through (also called) and the switching element 12 (3) Current path 1021B (current path 1021B (3) The current Id3 flowing through (also known as) may be split into two.
[0080] Each current path 1021B, ... may have an antiparallel section 510 arranged to allow current to flow in opposite directions from other current paths 1021B. The antiparallel section 510 is connected to the Nth switching element 12 among the multiple current paths 1021A. (N) Current path 1021A passing through (where N is an integer of 1 ≤ N ≤ n-1) (N) and the N+1 switching element 12 (N+1) Current path 1021A (N+1) It may be provided between them. In this embodiment, as an example, the antiparallel portion 510 is located in the current path 1021A (1) and current path 1021A (2) It is provided between them, and current path 1021A (2) and current path 1021A (3) They may be provided in between. The current paths 1021B of the antiparallel section 510 may be arranged antiparallel to each other. The current paths 1021B of the antiparallel section 510 may be arranged adjacent to each other so that they act differentially on each other and cancel out the magnetic field.
[0081] The drive unit 5B includes a plurality of sensors 51B, a detection unit 52A, and a cutoff control unit 55. The number of the plurality of sensors 51B may be less than the number of the plurality of switching elements 12, and may be n-1 (two as an example in this embodiment).
[0082] Each sensor 51B may be the same as the sensor 51 in the first embodiment. Multiple sensors 51B may measure parameters corresponding to the difference in current flow between the current path 1021 passing through the Nth switching element 12 and each current path 1021 passing through the N+1th switching element 12. As an example, among the n-1 sensors 51B, the first sensor 51B (1) The first switching element 12 (1) Current path 1021B (1) And the second switching element 12 (2) Current path 1021B (2) The induced voltage Vm1 corresponding to the total current flowing through the antiparallel section 510 may be measured. Second sensor 51B (2) The second switching element 12 (2) Current path 1021B (2) And the third switching element 12 (3) Current path 1021B (3) The induced voltage Vm2 corresponding to the total current flowing through the antiparallel section 510 may be measured.
[0083] [2.3.2. Modification of the second embodiment (2)] Figure 11 shows a power converter 1C according to a modified example (2) of the second embodiment. The power converter 1C has four or more (four in this embodiment as an example) switching elements 12, ... (switching elements 12 (1) ,12 (2) ,12 (3) ,12 (4) It comprises a drive unit 5C associated with each switching element 12, ... (also known as a switch element 12, ...).
[0084] Each switching element 12,... may be provided in a plurality of parallel current paths 1021C,... branching from a common current path. The common current path may be an output current path connected to the power output terminal 105, or it may be a negative power line 102. The current paths in this embodiment may branch in stages to form a branched structure or a hierarchical structure. For example, the common current path may branch once or multiple times into at least one pair of current paths 1021D leading to two or more equal numbers of switching elements 12,... In addition, each branched current path 1021 may branch into a current path 1021C that passes through the switching elements 12.
[0085] In this embodiment, as an example, the common current path is between two switching elements 12 (1) ,12 (2) Current path 1021D (1) and two switching elements 12 (3) ,12 (4) Current path 1021D (2) It is permissible to branch once. Of these, current path 1021D (1) is a switching element 12 (1) Current path 1021C (1) and switching element 12 (2) Current path 1021C (2) It may be branched into two. Current path 1021D (2) is a switching element 12 (3) Current path 1021C (3) and switching element 12 (4) Current path 1021C (4) It may be branched into two. As a result, the current Id flowing through the common current path is current path 1021D (1) The current Id10 (=Id1+Id2) flowing through it, and the current path 1021D (2) The current flowing through it, Id20 (=Id3+Id4), may be split into other currents. Current path 1021D (1) The current Id10 flowing through is in current path 1021C. (1) The current Id1 flowing through and the current path 1021C (2) The current flowing through it, Id2, may be split into two. Current path 1021D (2)The current Id20 flowing through is in current path 1021C. (3) The current Id3 flowing through and the current path 1021C (4) The current Id4 flowing through it may be split into two.
[0086] Each current path 1021D may have an antiparallel section 510D arranged to allow current to flow in opposite directions from other current paths 1021D. The current paths 1021D of the antiparallel sections 510D may be arranged antiparallel to each other. The current paths 1021D of the antiparallel sections 510D may be arranged adjacent to each other so that they act differentially and cancel out the magnetic fields.
[0087] Each current path 1021C, ... may have an antiparallel section 510C arranged to allow current to flow in opposite directions from other current paths 1021C. The antiparallel section 510C may be provided between a current path 1021C that passes through one switching element 12 and a current path 1021C that passes through a different switching element 12. For example, the antiparallel section 510C may be provided between current paths 1021C, 1021C that branch off from a common current path 1021D. The current paths 1021C of the antiparallel section 510C may be arranged antiparallel to each other. The current paths 1021C of the antiparallel section 510C may be arranged adjacent to each other so that they act differentially on each other and cancel out the magnetic field.
[0088] The drive unit 5C includes a plurality of sensors 51C, a detection unit 52C, and a cutoff control unit 55. The number of the plurality of sensors 51C may be less than the number of the plurality of switching elements 12. In this embodiment, as an example, the number of the plurality of sensors 51C may be 3, and the number of the plurality of switching elements 12 may be 4.
[0089] Each sensor 51C may be the same as the sensor 51 in the first embodiment. At least one of the multiple sensors 51C (sensor 51C (10)The sensor (also known as) may measure a parameter corresponding to the difference in current flowing through at least one pair of current paths 1021D. In other words, sensor 51C (10) The parameters corresponding to the total current flowing through the antiparallel portion 510 of the upper-level current path 1021D in the hierarchical structure of current paths 1021D and 1021C may be measured. In this embodiment, as an example, sensor 51C (10) This is current path 1021D (1) And, current path 1021D (2) The induced voltage Vm10 corresponding to the total current flowing through the antiparallel section 510 is measured.
[0090] Also, sensor 51C (10) Each sensor 51C other than the first sensor may measure a parameter corresponding to the difference in current flowing through a pair of different current paths 1021C, 1021C from among the multiple current paths 1021C. In this embodiment, as an example, the first sensor 51C (1) This is current path 1021C (1) And, current path 1021C (2) The induced voltage Vm1 corresponding to the total current flowing through the antiparallel section 510 is measured. Also, the second sensor 51C (2) This is current path 1021C (3) And, current path 1021C (4) The induced voltage Vm2 corresponding to the total current flowing through the antiparallel section 510 is measured.
[0091] The detection unit 52C may have three determination units 520 that correspond one-to-one with each sensor 51C, and an OR gate 521.
[0092] [3. Other variations] In the first and second embodiments described above, the drive devices 5, 5A to 5C were described as having a drive unit 50 and a cutoff control unit 55, but they do not necessarily have to have at least one of these. If the drive devices 5, 5A to 5C do not have a drive unit 50 or a cutoff control unit 55, they may output a detection signal S2 to an external device indicating that an abnormality has occurred when the measurement parameters from the sensors 51, 51A to 51C fall outside the reference range.
[0093] Furthermore, although sensors 51, 51A to 51C were described as measuring parameters corresponding to the difference in element currents of parallel-connected switching elements 12, they may also measure parameters corresponding to the difference in element currents of other types of semiconductor elements connected in parallel (for example, diodes or light-emitting diodes). In this case, the interruption control unit 55 may drive a switching element separate from the parallel-connected semiconductor elements to interrupt the current flowing through the parallel-connected semiconductor elements. Also, the drive devices 5, 5A to 5C may be provided in devices of a different type than the power conversion devices 1, 1A to 1C.
[0094] Furthermore, although it has been explained that sensors 51, 51A to 51C are provided on the drain side of the switching element 12, they may also be provided on the source side.
[0095] Although the present invention has been described above using embodiments, the technical scope of the present invention is not limited to the scope described in the above embodiments. It will be apparent to those skilled in the art that various modifications or improvements can be made to the above embodiments. It will be clear from the claims that such modified or improved forms may also be included in the technical scope of the present invention.
[0096] It should be noted that the execution order of operations, procedures, steps, and stages in the apparatus, systems, programs, and methods shown in the claims, specifications, and drawings is not explicitly stated as "before," "prior to," etc., and that these can be implemented in any order unless the output of a previous process is used in a later process. Even if the operation flow in the claims, specifications, and drawings is described using phrases such as "first," "next," etc. for convenience, it does not mean that it is essential to perform the operations in that order. [Explanation of symbols]
[0097] 1. Power converter 2. Drive unit 5. Drive unit 11 Switching elements 12 Switching elements 50 Drive unit 51 Sensors 52 Detection unit 55 Interruption control unit 101 Positive power line 102 Negative power line 105 Power output terminal 510 anti-parallel part 520 Judgment section 521 OR Gate 550 NOT Gate 551 AND gate 1011 Current Path 1021 Current Path
Claims
1. A sensor that measures a parameter corresponding to the difference in current flow between a current path that branches off from a common current path and passes through one semiconductor element among multiple semiconductor elements connected in parallel, and a current path that passes through another semiconductor element. A detection unit detects that an abnormality has occurred when the parameter measured by the sensor falls outside the reference range, Equipped with, The detection unit detects whether the parameter measured by the sensor falls outside the reference range at a reference time elapsed from the input timing of the turn-on signal to the plurality of semiconductor elements. The aforementioned reference time is less than the time from the input timing of the turn-on signal until the plurality of semiconductor elements reach a steady-state on state.
2. The apparatus according to claim 1, wherein the sensor measures the parameter corresponding to the total current of an antiparallel portion arranged such that current flows in opposite directions between a current path branching from the common current path and passing through one semiconductor element and a current path passing through the other semiconductor element.
3. Equipped with multiple of the aforementioned sensors, The apparatus according to claim 1, wherein each of the plurality of sensors measures the parameter corresponding to the difference in current flowing through a pair of different current paths, which are among a plurality of current paths that branch off from the common current path and pass through each of the plurality of semiconductor elements.
4. The apparatus according to claim 3, wherein the number of the plurality of sensors is less than the number of the plurality of semiconductor elements.
5. The apparatus according to claim 3 or 4, wherein the plurality of sensors measure the parameter corresponding to the difference in current flowing through a current path passing through one semiconductor element and a current path passing through each semiconductor element different from the one semiconductor element.
6. The plurality of semiconductor elements each have n semiconductor elements (where n is an integer of 2 or more). The apparatus according to claim 3 or 4, wherein the plurality of sensors measure the parameter corresponding to the difference in current flowing through the current path passing through the Nth semiconductor element (where N is an integer of 1 ≤ N ≤ n-1) and the current path passing through the N+1th semiconductor element.
7. The apparatus according to claim 3 or 4, wherein the plurality of sensors have at least one sensor that measures the parameter corresponding to the difference in current flowing in at least one pair of current paths that branch off from the common current path and lead to two or more equal numbers of semiconductor elements among the plurality of semiconductor elements.
8. The apparatus according to claim 3 or 4, wherein the detection unit detects that an abnormality has occurred in response to the parameter measured by at least one of the sensors falling outside the reference range.
9. Each of the aforementioned plurality of semiconductor elements is a switching element, The apparatus described in claim 1, A power conversion device equipped with the following features.
10. The power conversion device according to claim 9, wherein each semiconductor element is a wide-bandgap semiconductor element.