WO2025079495A1 - Method and program for estimating power loss by device - Google Patents

Abstract

A method according to one aspect of the present invention relates to a method for estimating power loss caused by a device which includes a switching element capable of changing a resistance value, the method comprising the following steps: a heat flow measurement step for, by using a first heat flow sensor configured to exchange heat with a device in which a resistance value of the switching element is changed in a prescribed switching pattern, measuring a heat flow generated from the device, the switching pattern including a first pattern and a second pattern different from the first pattern; and an estimation step for estimating power loss by comparing, from among heat flow measurement results, a first contribution which is a contribution of the heat flow in the first pattern with a second contribution which is a contribution of the heat flow in the second pattern.

Description

Method and program for estimating power loss by a device

The present invention relates to a method and program for estimating power loss by a device.

Patent Document 1 discloses technology relating to a method and device for estimating the damage level or life expectancy of a power semiconductor module that includes at least one die mechanically, thermally, and electrically attached to a substrate composed of multiple layers of different materials.

The method and device described in Patent Document 1 obtains the power loss of a power semiconductor module, obtains the temperature at at least two different positions of the power semiconductor module, estimates a thermal model between at least two different positions of the power semiconductor module using the determined power loss and the obtained temperature, and determines whether a notification indicating a damage level or a life expectancy prediction must be issued according to the estimated thermal model and a reference thermal model, and if the determining step determines that a notification must be issued, notifies the level or location of the damage, or the life expectancy prediction.

Special table 2018-537061 publication

In this way, information about power loss when operating devices such as power semiconductor modules is important in various situations, such as the design and use of the device. However, with high-frequency devices such as power semiconductor modules, it is difficult to stably measure the load current, which changes at high frequencies, making it difficult to obtain reliable information about the device's power loss.

According to one aspect of the present invention, there is provided a method for estimating power loss due to a device including a switching element whose resistance value can be changed, the method including the following steps: in the heat flow measurement step, a first heat flow sensor configured to exchange heat with the device is used to measure the heat flow generated from the device, the resistance value of the switching element of which is changed in a specified switching pattern, the switching pattern including a first pattern and a second pattern different from the first pattern; and in the estimation step, the power loss is estimated by comparing the first contribution, which is the contribution of the heat flow due to the first pattern, with the second contribution, which is the contribution of the heat flow due to the second pattern, among the heat flow measurement results.

With this configuration, information about the power loss of a device can be estimated with higher reliability than, for example, when it is estimated only from the electrical characteristics of the device.

FIG. 1 is a diagram illustrating an example of the configuration of an estimation system 1. FIG. 2 is a block diagram showing the hardware configuration of a terminal 5. 1 is a flowchart showing the flow of an example of the method. 10A and 10B are diagrams showing changes over time in the voltage applied to a switching element, the current flowing through the switching element, and the power consumption of the switching element when two different patterns are applied to the switching element. FIG. 1 is a diagram illustrating an example of the configuration of an estimation system including a reference unit.

Below, an embodiment of the present invention will be described with reference to the drawings. The various features shown in the embodiments described below can be combined with each other. Note that in this specification and drawings, components having substantially the same functional configuration are designated by the same reference numerals to avoid redundant description.

Incidentally, the program for realizing the software appearing in one embodiment may be provided as a non-transitory computer-readable recording medium, or may be provided so that it can be downloaded from an external server, or may be provided so that the program is started on an external computer and its functions are realized on a client terminal (so-called cloud computing).

Furthermore, in various information processing according to one embodiment, an input and an output according to the input can be realized. Here, as long as an output is obtained as a result of the input, the form of the information referenced in such information processing (hereinafter referred to as reference information) is not limited. The reference information may be, for example, rule-based information such as a database, a lookup table, or a predetermined function (including a decision formula such as a regression formula constructed by a statistical method), or it may be a trained model that has previously learned the correlation between the input and the output, or it may be a large-scale language model that can output a desired result by inputting a prompt.

In one embodiment, a "part" may include, for example, a combination of hardware resources implemented by a circuit in the broad sense and software information processing that can be specifically realized by these hardware resources. In one embodiment, various information is handled, and this information is represented, for example, by physical values of signal values representing voltage and current, high and low signal values as a binary bit collection consisting of 0 or 1, or quantum superposition (so-called quantum bits), and communication and calculations can be performed on a circuit in the broad sense.

Furthermore, a circuit in the broad sense is a circuit realized by at least an appropriate combination of a circuit, circuits, a processor, and a memory. The processor may be a general-purpose processor or a dedicated circuit. That is, it includes application specific integrated circuits (ASICs), programmable logic devices (e.g., simple programmable logic devices (SPLDs), complex programmable logic devices (CPLDs), and field programmable gate arrays (FPGAs)).

In addition, from the viewpoint of responsiveness, the heat flow sensor described below is preferably a thin-film type thermoelectric conversion device based on the anomalous Nernst effect. The element (thermoelectric conversion element) of the thermoelectric conversion device may be composed of an alloy or compound exhibiting the anomalous Nernst effect. The element may be composed of, for example, a topological ferromagnet or a topological antiferromagnet called a Weyl semimetal, or may be composed of a ferrimagnetic material, or may be a combination of these. The topological ferromagnet may be a metal having a composition of Co ₂ TX such as Co ₂ MnGa (X is any one of Si, Ge, Sn, Al, and Ga), or may be an alloy of a known topological ferromagnet such as a metal having a composition formula of Fe ₃ X (X is a stoichiometric composition in which a typical element or a transition element such as Al or Ga is used). The topological antiferromagnet may be a known topological antiferromagnet such as Mn ₃ X (X is one or more elements selected from Sn, Ge, Ga, Pt, Ir, and Rh, or a compound thereof). The compound constituting the element may be, for example, an alloy containing a transition metal, and the alloy may be a compound having a crystal structure with a kagome lattice plane of the transition metal, and may exhibit the anomalous Nernst effect. The ferrimagnetic material is also not particularly limited as long as it exhibits the anomalous Nernst effect. The structure of the element is not particularly limited, and known materials can be used. The element according to this embodiment may be provided by sputtering, deposition, MBE, plating, granulation, 3D printing, melting, sintering, printing, pasting, or the like. Since the thin-film type heat flow sensor based on the anomalous Nernst effect is an alloy, the thermal resistance and heat capacity are lower than those of a heat flow sensor that generates the Seebeck effect. Therefore, the sensitivity is higher than that of a conventional heat flow sensor that generates the Seebeck effect, and the time response is excellent. The thickness of the heat flow sensor element is not particularly limited, but it is preferably less than 1 micrometer. The heat flow sensor may be a heat flow sensor that generates the Seebeck effect described above. In order to enhance thermal response, for example, the thickness of the Seebeck effect element is preferably less than 250 micrometers, more preferably less than 100 micrometers, more preferably less than 10 micrometers, and even more preferably less than 1 micrometer.

1. Example of System Configuration This section describes an example of the configuration of an estimation system 1 for estimating power loss due to a device. Fig. 1 is a diagram showing an example of the configuration of the estimation system 1. As shown in Fig. 1, the estimation system 1 includes a semiconductor device 2, which is an example of a device, a first heat flow sensor 3a, a measurement device 4, and a terminal 5.

The semiconductor device 2 is any device that uses a switching element, such as an integrated circuit (IC) or a power converter. For example, the semiconductor device 2 includes a substrate 21, an element portion 22, and a housing 23.

The substrate 21 is configured to have electrical insulation. The substrate 21 has electrical insulation, for example, a Si substrate. The substrate 21 may be a flexible substrate.

The element section 22 is formed on the substrate 21, and is configured to perform various signal processing and information processing by inputting an electrical signal from the outside. As an example, the element section 22 includes a switching element 221 that can change its resistance value. The switching element 221 is configured to be able to switch between an ON state with a low resistance value and an OFF state with a high resistance value based on an electrical signal (e.g., voltage or current). Examples of the switching element 221 include a field effect transistor (FET) and an insulated gate bipolar transistor (IGBT). In addition to the switching element 221, the element section 22 may include various elements such as a resistance element, a capacitance, an inductance, and a power storage device.

The switching element 221 generates power loss when driven by an external electrical signal. The power loss can include switching loss caused by the current that flows when the switching element 221 completely switches between the ON state and the OFF state, and conduction loss caused by the remaining resistance value when the switching element 221 is in the ON state.

The housing 23 is configured to protect the element unit 22 from external physical interference and electromagnetic interference. As an example, the housing 23 is configured to cover the element unit 22 together with the substrate 21. It is preferable that the housing 23 has lower thermal conductivity than the substrate 21, for example, be a thermal insulator. With this configuration, the outflow path of heat associated with power loss from the element unit 22 can be limited to the substrate 21, etc. The presence or absence of the housing 23 is optional.

The first heat flow sensor 3a is configured to output an electrical signal (e.g., thermoelectromotive force) corresponding to the flowing heat flow. The first heat flow sensor 3a may be implemented, for example, using a thermoelectric conversion device based on the anomalous Nernst effect as described above. The first heat flow sensor 3a may be arranged to measure the heat flow from the element portion 22 through the substrate 21. For example, the first heat flow sensor 3a may be arranged to face the surface of the substrate 21 opposite to the surface on which the element portion 22 is provided. For example, the first heat flow sensor 3a (and the second heat flow sensor 3b described later) is configured to output a signal that has a positive correlation with a heat flow such as a thermoelectromotive force. In particular, since the switching element 221 generates heat due to power loss, heat may flow from the switching element 221 to the first heat flow sensor 3a in approximately the same direction. In this case, the first heat flow sensor 3a is configured to output a so-called DC signal in which the positive and negative of the output signal are not inverted.

The measuring device 4 is configured to measure the heat flow generated from the semiconductor device 2 in which the resistance value of the switching element 221 is changed in a specified switching pattern, using the first heat flow sensor 3a configured to exchange heat with the semiconductor device 2. For example, the measuring device 4 includes an AC power source that applies an electrical signal corresponding to a specified switching pattern to the switching element 221. The measuring device 4 may also include a measuring instrument (e.g., a voltmeter or ammeter) for measuring the electrical signal output from the first heat flow sensor 3a in association with the heat flow from the semiconductor device 2. The measuring device 4 may also include a circuit capable of performing various calculations (e.g., signal integration) on the measurement results of the first heat flow sensor 3a.

FIG. 2 is a block diagram showing the hardware configuration of the terminal 5. The terminal 5 includes a communication bus 50, a communication unit 51, a storage unit 52, a processor 53, a display unit 54, and an input unit 55. These components are electrically connected inside the terminal 5 via the communication bus 50.

The communication unit 51 is preferably a wired communication means such as USB, IEEE 1394, Thunderbolt (registered trademark), wired LAN network communication, etc., but may also include wireless LAN network communication, mobile communication such as 3G/LTE/5G, BLUETOOTH (registered trademark) communication, etc. as necessary. In other words, it is more preferable to implement it as a collection of multiple communication means. In other words, the terminal 5 may communicate various information from the outside via the communication unit 51 and the network.

The memory unit 52 stores various information defined by the above description. This can be implemented, for example, as a storage device such as a solid state drive (SSD) that stores various programs and the like related to the terminal 5 executed by the processor 53, or as a memory such as a random access memory (RAM) that stores temporarily required information (arguments, arrays, etc.) related to the program calculations. The memory unit 52 stores various programs and variables and the like related to the terminal 5 executed by the processor 53.

The processor 53 processes and controls the overall operations related to the terminal 5. The processor 53 is, for example, a central processing unit (CPU) not shown. The processor 53 realizes various functions related to the terminal 5 by reading out specific programs stored in the memory unit 52. In other words, information processing by software stored in the memory unit 52 is specifically realized by the processor 53, which is an example of hardware, and can be executed as various functional units included in the processor 53.

For example, the processor 53 is configured as an acquisition unit to be capable of acquiring information from the measurement device 4 or other devices. The processor 53 is configured to be capable of acquiring the thermoelectromotive forces of the first heat flow sensor 3a and the second heat flow sensor 3b via the measurement device 4, for example. The processor 53 is also configured to be capable of acquiring various pieces of information by reading out various pieces of information stored in a storage area that is at least a part of the memory unit 52 and writing the read out information in a working area that is at least a part of the memory unit 52. The storage area is, for example, an area of the memory unit 52 that is implemented as a storage device such as an SSD. The working area is, for example, an area that is implemented as a memory such as a RAM.

The processor 53 is configured to be able to output various information. An external device (not shown) can execute various controls based on the information output from the processor 53. The information can be presented to the user via the display unit 54 of the terminal 5 or another device. In such a case, for example, the processor 53 controls the display unit 54 of the terminal 5 to display visual information such as a screen, an image including a still image or a video, an icon, a message, etc. The processor 53 may generate only rendering information for displaying the visual information on the terminal 5. The processor 53 may present the output information to the user without going through the terminal 5 or another device.

The processor 53 is not limited to being single, and may be implemented with multiple processors 53 for each function. It may also be a combination of these.

The display unit 54 may be included in the housing of the terminal 5 or may be attached externally. The display unit 54 displays a screen of a Graphical User Interface (GUI) that can be operated by the user. This is preferably implemented by using display devices such as a CRT display, a liquid crystal display, an organic EL display, and a plasma display, depending on the type of the terminal 5.

The input unit 55 may be included in the housing of the terminal 5, or may be attached externally. For example, the input unit 55 may be implemented as a touch panel integrated with the display unit 54. A touch panel allows the user to input tapping, swiping, and the like. Of course, a switch button, a mouse, a QWERTY keyboard, and the like may be used instead of a touch panel. That is, the input unit 55 accepts operation inputs made by the user. The input is transferred as a command signal to the processor 53 via the communication bus 50, and the processor 53 can execute predetermined control or calculations as necessary.

The measuring device 4 and the terminal 5 do not have to be separate entities, but may be integrated.

Returning to FIG. 1, the semiconductor device 2 is preferably configured so that heat from the element portion 22 flows out in a concentrated manner toward the substrate 21. As an example of a configuration for causing heat from the element portion 22 to flow out in a concentrated manner toward the substrate 21, the semiconductor device 2 may further include a heat sink 24. The heat sink 24 is configured to promote cooling of the element portion 22 by discharging heat generated from the element portion 22 to the outside. For example, the heat sink 24 is configured to be connected to the substrate 21. At this time, the heat generated from the element portion 22 is transferred to the heat sink 24 via the substrate 21. This can promote the heat generated in the element portion 22 to flow out through a portion of the substrate 21 or the like. The substrate 21 and the heat sink 24 may be integrated. The heat sink 24 may be disposed, for example, between the substrate 21 and the heat flow sensor 3. The first heat flow sensor 3a may be disposed between the substrate 21 and the housing 23. With this configuration, it becomes easier to comprehensively measure the heat flowing from the element portion 22 toward the heat sink 24.

The heat flow through the first heat flow sensor 3a may differ depending on the temperature of the surface of the first heat flow sensor 3a opposite the surface connected to the semiconductor device 2. Therefore, in order to keep the temperature of one surface of the first heat flow sensor 3a constant, a temperature adjustment mechanism such as a Peltier element, heater, thermostat, or fan, or a combination of a heat sink with a large thermal capacity and a temperature adjustment mechanism may be provided.

The estimation system 1 may be configured to guide outflow heat to the first heat flow sensor 3a by covering the element portion 22 with a heat insulating material. With such a configuration, the outflow path of heat generated from the switching element 221 can be limited to a certain area of the substrate 21, etc., and power loss can be estimated more accurately. The specific manner of covering the element portion 22 with a heat insulating material is arbitrary. For example, the estimation system 1 may be configured to cover the element portion 22 with a heat insulating material by forming the housing 23 with a heat insulating material, or by extrapolating a heat insulating material that covers the element portion 22 to the outside or the outside of the housing 23. The heat insulating material may also be a vacuum layer.

The estimation system 1 may also be configured to cover the element portion 22 with a heat conductive member and to guide the outflow heat to the first heat flow sensor 3a via the heat conductive member by connecting the heat conductive member to the first heat flow sensor 3a or the substrate 21. With this configuration, the first heat flow sensor 3a can measure the heat flowing out from a path other than the path passing through a specific area of the substrate 21, etc., through the heat conductive member. Therefore, the accuracy of estimating the power loss can be further improved. The specific manner of covering the element portion 22 with a heat conductive member is arbitrary. For example, the estimation system 1 may be configured to cover the element portion 22 with a heat insulating member by forming the housing 23 with a heat conductive member, or by extrapolating a heat insulating member that covers the element portion 22 to the outside or outside of the housing 23. In this way, the estimation system 1 can be configured to use a heat insulating member or a heat conducting member to guide the outflow heat from the element unit 22 toward the housing 23 to the first heat flow sensor 3a, and to measure the heat flow from the element unit 22, including the induced outflow heat, using the first heat flow sensor 3a.

Furthermore, the semiconductor device 2 may include a guard heater 25 that functions as an ambient temperature adjustment unit. The guard heater 25 is configured to be able to adjust its temperature so as not to come into thermal contact with the guard heater 25, so as to reduce the difference between the temperature of the element portion 22 and the temperature around the element portion 22 (for example, the temperature of the air adjacent to the housing 23). The guard heater 25 is configured to generate heat according to the surface temperature of the element portion 22 (and further the surface temperature of the housing 23), for example. The surface temperature can be measured by various methods, such as using a thermometer built into the surface of the housing 23 or inside the element portion 22. In other words, by placing the outside of the housing 23 in a vacuum environment or using a guard heater 25 that is isothermal with the housing 23, it is possible to prevent heat from being released from the housing 23 to the outside.

The semiconductor device 2 may further include a terminal 26 for connecting the element portion 22 to another element (not shown). The terminal 26 is configured to function as a port of the element portion 22 and is electrically connected to the element portion 22 directly or via the substrate 21. Since the terminal 26 has electrical conductivity, it tends to have a higher thermal conductivity than an electrical insulator such as the substrate 21. Therefore, the terminal 26 can be a heat outflow path different from the substrate 21. In this case, it is preferable to place the second heat flow sensor 3b on the terminal 26. This makes it possible to more comprehensively measure the heat flowing through the main outflow path of the heat generated from the switching element 221. In this case, the estimation system 1 may be configured to estimate the power due to the power loss using the measurement device 4 based on the measurement result of the heat flow from the substrate 21 by the first heat flow sensor 3a and the measurement result of the heat flow from the terminal by the second heat flow sensor 3b. With this configuration, the power P due to the power loss of the switching element 221 can be more accurately estimated. For insulation, an insulating sheet (not shown) may be provided between the terminal 26, which serves as a heat flow path, and the second heat flow sensor 3b. Furthermore, the semiconductor device 2 included in the estimation system 1 may be attached to the heat flow sensor 3 using a PIN jig with as few contacts as possible during manufacturing. This makes it difficult for heat to escape from a path that does not pass through the heat flow sensor 3 of the semiconductor device 2, improving the accuracy of the power loss estimation.

2. Example of a method for estimating power loss Next, an example of a method for estimating power loss due to the semiconductor device 2 will be described using the semiconductor device 2 as an example. Fig. 3 is a flowchart showing the flow of the example of the method.

[Step S1]
First, in step S1, a first heat flow sensor 3a is placed on the semiconductor device 2. In this embodiment, a second heat flow sensor 3b may also be placed. A guard heater 25 may be placed around the element portion 22 of the semiconductor device 2. These placements may be performed manually or mechanically. If the first heat flow sensor 3a and the like are placed on the semiconductor device 2 in advance, the process of step S1 may be omitted as appropriate.

[Step S2]
Next, in step S2, the processor 53 sets a switching pattern of an electric signal (here, a gate voltage) to be applied to the semiconductor device 2. The switching pattern is configured to define a time change in the gate voltage V to be applied to the switching element 221. In this embodiment, the switching pattern is configured to periodically switch the switching element 221 between ON and OFF, and is characterized by a frequency corresponding to the period T.

As an example, the processor 53 sets a switching pattern including a first pattern PT1 and a second pattern PT2 different from the first pattern PT1. For example, the processor 53 sets parameters (e.g., frequency band, applied voltage, period for applying the pattern, etc.) that characterize each of the patterns PT1, PT2. Figure 4 is a diagram showing the change over time in the voltage applied to the switching element, the current flowing through the switching element, and the power consumption in the switching element when two different patterns are applied to the switching element. As shown in Figure 4, the first pattern PT1 is configured so that the state of the switching element 221 changes in a first period T1. For example, the first pattern PT1 is configured to repeat an ON period T11 during which the switching element 221 is in an ON state, a first transition period T12 during which the switching element 221 transitions from an ON state to an OFF state, an OFF period T13 during which the switching element 221 is in an OFF state, and a second transition period T14 during which the switching element 221 transitions from an OFF state to an ON state in sequence. As an example, the lengths of the ON period T11 and the OFF period T13 may be equal. With this configuration, the calculation for estimating the power loss becomes simpler, and the calculation load can be reduced. In FIG. 4, the current flowing through the switching element 221 during switching according to the first pattern PT1 is I1, the voltage drop (e.g., source-drain voltage) along the current path is V1, and the power consumption of the switching element 221 based on the current I1 and voltage V1 is Q1.

The second pattern PT2 is configured so that the state of the switching element 221 changes in a second period T2 that is longer than the first period T1. For example, the second pattern PT2 is configured to sequentially repeat an ON period T21 in which the switching element 221 is in the ON state, a first transition period T22 in which the switching element 221 transitions from the ON state to the OFF state, an OFF period T23 in which the switching element 221 is in the OFF state, and a second transition period T24 in which the switching element 221 transitions from the OFF state to the ON state. As an example, the lengths of the ON period T11 and the OFF period T13 may be equal. With such a configuration, the calculation for estimating the power loss becomes simpler, and the calculation load can be reduced. In FIG. 4, the current flowing through the switching element 221 while switching is performed according to the second pattern PT2 is I2, the voltage drop (e.g., source-drain voltage) along the current path is V2, and the power consumption of the switching element 221 based on the current I2 and voltage V2 is Q2. The relationship between the first period T1 and the second period T2 is arbitrary, but for example, the second period T2 is an integer multiple of the first period T1. With this configuration, the switching pattern of the signal applied to the switching element 221 can be simplified, making it easier to estimate power loss.

The power loss caused by the switching element 221 includes conduction loss and switching loss. Conduction loss is power consumption caused by leakage current and the like when the switching element 221 is in a fixed state, either ON or OFF. Conduction loss is represented in particular by the power consumption during the ON periods T11, T21 and the OFF periods T13, T23.

Switching loss is power consumption caused by current flowing in an intermediate state that appears when the state of the switching element 221 transitions (switches) from one state to another. Switching loss is mainly included in the power consumption during the first transition periods T12, T22 and the second transition periods T14, T24.

[Step S3]
Returning to FIG. 3, next, in step S3, the measuring device 4 drives the semiconductor device 2 based on the switching pattern set by the terminal 5. For example, the measuring device 4 drives the switching element 221 of the semiconductor device 2 by applying a gate voltage to the switching element 221 based on the first pattern PT1 and the second pattern PT2. As an example, the measuring device 4 independently drives the semiconductor device 2 based on the first pattern PT1 and the second pattern PT2. With this configuration, it is possible to suppress crosstalk of signals in each pattern PT1 and PT2, and to reduce noise that may affect the estimation of power loss. Specifically, the measuring device 4 alternately drives the semiconductor device 2 based on the first pattern PT1 and the second pattern PT2 so that the first pattern PT1 and the second pattern PT2 do not overlap.

As another example, the measuring device 4 drives the semiconductor device 2 using a switching pattern in which the first pattern PT1 and the second pattern PT2 are superimposed. The specific form of superimposition is arbitrary, but for example, the measuring device 4 may apply a composite voltage (V1+V2) obtained by adding the voltage V1 of the first pattern PT1 and the voltage V2 of the second pattern PT2 to the switching element 221. With this configuration, the heat flow can be measured in a shorter time than when the voltage V1 of the first pattern PT1 and the voltage V2 of the second pattern PT2 are applied to the switching element 221 separately. When the semiconductor device 2 (switching element 221) is driven, the switching element 221 generates heat in accordance with the power consumption Q1 (or Q2). The heat flow associated with the heat generation flows to the first heat flow sensor 3a via the substrate 21 (and the heat sink 24), or to the second heat flow sensor 3b via the terminal 26. As a result, each of the first heat flow sensor 3a and the second heat flow sensor 3b generates a thermoelectromotive force according to the heat flow from the switching element 221.

[Step S4]
Next, in step S4, the measuring device 4 measures the output (e.g., thermoelectromotive force) from the first heat flow sensor 3a and the second heat flow sensor 3b. The measurement result can be expressed as time-series data of the thermoelectromotive force. The time-series data may represent a time-series change in the total value (integral value) of the thermoelectromotive force over a certain period of time.

[Step S5]
Next, in step S5, the processor 53 identifies a first contribution, which is a contribution of the heat flow due to the first pattern PT1, and a second contribution, which is a contribution of the heat flow due to the second pattern PT2, from the measurement result of the heat flow in step S4. For example, when the driving of the semiconductor device 2 based on the first pattern PT1 and the driving of the semiconductor device 2 based on the second pattern PT2 are performed independently, the processor 53 identifies the integrated value of the thermoelectromotive force during the period in which the driving based on the first pattern PT1 was performed as the first contribution, and identifies the integrated value of the thermoelectromotive force during the period in which the driving based on the second pattern PT2 was performed as the second contribution, from among the periods included in the measurement result. If it is difficult to separate these periods, the processor 53 may identify each contribution by performing a filter process to separate the frequencies f1 and f2 (the reciprocals of the periods T1 and T2) that characterize each pattern PT1 and PT2, or by performing frequency separation using a lock-in method. In addition, when the driving based on the first pattern PT1 and the driving based on the second pattern PT2 are performed discontinuously and separately, the processor 53 may identify the integrated values of the thermoelectromotive forces measured during each driving as the first contribution and the second contribution, respectively. In addition, when the semiconductor device 2 is driven using a switching pattern in which the first pattern PT1 and the second pattern PT2 are superimposed, the processor 53 may identify each contribution by performing a filter process to separate the frequencies f1 and f2 (the reciprocals of the periods T1 and T2) that characterize each pattern PT1 and PT2, or by performing frequency separation using a lock-in method. In such various modes, the processor 53 may extract the first contribution and the second contribution from the measurement results. The first contribution and the second contribution are expressed, for example, as the heat generation amounts W1 and W2 in an integration period (for example, a period that characterizes each pattern PT1 and PT2, such as the first period T1 and the second period T2) in which the power consumption is integrated. The amount of heat generated W1 as the first contribution is the integrated value of the power consumption Q1 within the integration period in the first pattern PT1, and the amount of heat generated W2 as the second contribution is the integrated value of the power consumption Q2 within the integration period in the second pattern PT2.

[Step S6]
Next, in step S6, the first contribution W1 and the second contribution W2 identified in step S5 are compared to estimate the power loss of the switching element 221. With this configuration, information regarding the power loss of the device can be estimated with higher reliability than, for example, a case in which it is estimated only from the electrical characteristics of the device.

Here, we will explain an example of a method for estimating power loss based on the first contribution W1 and the second contribution W2. The time averages of the power consumption Q1 and Q2 for each period T11-T14 and T21-T24 included in each pattern PT1 and PT2 are W11-W14 and W21-W24. In this case, the first contribution W1 and the second contribution W2 are expressed as follows.

Wij is the time average of the power consumption Q1, Q2 in each period Tij (T11-T14, T21-T24). In each pattern PT1, PT2, each period Tij (T11-T14, T21-T24) is assumed to be known. The first contribution W1 and the second contribution W2 thus formulated are expressed as W12, W14, W22, and W24 based on the conduction loss, and W11, W13, W21, and W23 based on the conduction loss and the switching loss. Therefore, it is particularly important to estimate the switching loss, which is the main power loss in the switching element 221, using the first contribution W1 and the second contribution W2.

Here, the above two equations include a total of eight parameters Wij, 2 x 4 types. Among them, the average power loss corresponding to the same state is assumed to be the same in the first pattern PT1 and the second pattern PT2, and W1j = W2j is assumed. This reduces the number of parameters to four. Also, when the switching element 221 is in the OFF state, the current flowing through the switching element 221 is almost zero, so W13 = W23 corresponding to the OFF periods T13 and T23 may be assumed to be zero. This reduces the number of parameters of the simultaneous linear equations expressed by equation (1) to three. Furthermore, it is reasonable to a certain extent to assume that the time average W12 = W22 of the power consumption in the first transition period T12, T22 and the time average W14 = W24 of the power consumption in the second transition period T14, T24 are equal, for example, considering the reversibility of the phenomenon. Therefore, by setting W12 = W14, the number of parameters of the above equation (1) is two.

The patterns included in the switching pattern can define a simultaneous linear equation according to the number n of the patterns. For example, by using an approximation based on the above assumption, the processor 53 can reduce the number of parameters included in the simultaneous linear equation to two. Therefore, the processor 53 can estimate the content of the power loss using the contributions W1 and W2 of the two patterns PT1 and PT2, respectively. In particular, the power loss in the transition periods T12, T22, T14, and T24 includes the conduction loss and the switching loss, as described above. Therefore, by assuming that the conduction loss in the transition periods T12, T22, T14, and T24 is equal to W11, which represents the conduction loss in the ON period obtained by solving the simultaneous linear equation, the switching loss is obtained as (W12-W11). In this way, the processor 53 can estimate the contribution of the switching loss and the contribution of the conduction loss included in the power loss by comparing the first contribution with the second contribution. Furthermore, by increasing the number of patterns according to the number of parameters in the simultaneous linear equations, it is possible to perform more accurate estimation with fewer approximations.

Here, the first transition periods T12, T22 and the second transition periods T14, T24 become shorter and occur more frequently as the switching speed of the switching element 221 increases. Accordingly, as the speed (in other words, the frequency) of the semiconductor device 2 increases, the switching loss increases, while the switching noise increases. This tends to make it difficult to estimate the power loss (particularly the switching loss) by directly measuring the voltage and current applied to the switching element 221.

By adopting the above-mentioned method, the power loss can be observed as a DC signal (thermoelectromotive force) output from the first heat flow sensor 3a and the second heat flow sensor 3b. This makes it possible to estimate the power loss of the switching element 221 even when it is difficult to observe the electrical properties of the switching element 221 due to switching noise.

3. Another Example of the Estimation System 1 The estimation system 1 may further include a reference unit as an example of a physical model that simulates the heat generation state of the semiconductor device 2. FIG. 5 is a diagram showing a configuration example of an estimation system including a reference unit. As shown in FIG. 5, the estimation system 1 may further include a reference unit 6 and a reference heat flow sensor 7 configured to be able to measure the heat flow from the reference unit 6. The reference unit 6 is configured to reproduce the behavior of the semiconductor device 2 regarding the heat flow using a heat source capable of controlling the amount of heat generated by a heat generating body or the like. Note that, in FIG. 5, the configurations of the guard heater 25, the terminal 26, and the like shown in FIG. 1 are not shown in order to simplify the explanation, but the semiconductor device 2 shown in FIG. 5 may also include the various configurations of the semiconductor device 2 described using FIG. 1.

As shown in FIG. 5, the reference unit 6 may include, for example, a substrate 61 and a heat generating portion 62, as well as a housing 63 and a heat sink 64. The substrate 61, housing 63, and heat sink 64 are similar to the substrate 21, housing 23, and heat sink 24, and therefore will not be described.

The heat generating section 62 is a member corresponding to the element section 22 in the semiconductor device 2, and includes a heat generating element 621 that generates heat. The heat generating element 621 may be implemented using a heater circuit or a metal plate that generates eddy currents by induction. The processor 53 creates a calibration curve (heat flow sensor output versus input power) from the power input to the heat generating element 621. The calibration curve may be stored in, for example, the storage section 52. The processor 53 may estimate the actual power loss of the semiconductor device 2, for example, by applying the measured value measured by the first heat flow sensor 3a to the calibration curve. In other words, the estimation system 1 may be configured to estimate power loss by comparing the measurement results of the heat flow in a physical model simulating the semiconductor device 2 with the measurement results of the first heat flow sensor 3a.

The reference heat flow sensor 7 is configured to measure a heat flow based on heat generated from the heat generating element 621 through the housing 63 (and heat sink 64) in the same manner as the first heat flow sensor 3a for the semiconductor device 2. The reference heat flow sensor 7 can be configured, for example, in the same manner as the first heat flow sensor 3a.

The reference unit 6 is preferably designed to simulate the thermal conductivity and volume inside the semiconductor device 2. Furthermore, in a situation where the semiconductor device 2 is actually used, the time to be applied to the calibration curve in each of the steady state (ON period and OFF period) and the transient state (first transition period and second transition period) may be determined. This can improve the accuracy of the estimation of the power loss. Furthermore, a physical model simulating this reference unit 6 may be designed in a simulation. This can improve the estimation accuracy of the value of the power loss relative to the measurement value of the first heat flow sensor 3a, even without providing an actual reference unit 6.

[others]
The above-described estimation system 1 and the estimation method using the estimation system 1 are merely examples, and are not limited to these. For example, the above-described estimation system 1 and the like can be modified as follows.

The switching pattern may include at least two patterns (e.g., a first pattern PT1 and a second pattern PT2), and may include three or more types of switching patterns. Furthermore, each pattern is not limited to being periodic, and may be non-periodic (e.g., a random pattern).

The estimation system 1 may also estimate the heat flow from the power semiconductor to the footprint, etc., by measuring the temperature of the semiconductor device 2 and the temperature of the terminals 26, etc., of the semiconductor device 2 using the processor 53, etc. Note that it is preferable to measure the temperature at all footprints, etc. to which the terminals 26 are connected, but accuracy can be improved by making an estimate at only at least one point.

The device including such a switching element 221 is not limited to a semiconductor device 2 such as a MOSFET or IGBT, and can be any device.

The first heat flow sensor 3a does not have to be provided on the substrate 21 or the heat sink 24. For example, the first heat flow sensor 3a may be provided on the housing 23, etc., as long as it is an area where heat from the switching element 221 flows preferentially.

Aspects of the above-described embodiment may be a program. The program causes at least one computer to execute each step of the estimation method.

Furthermore, it may be provided in the following forms:

(1) A method for estimating power loss due to a device including a switching element whose resistance value can be changed, comprising the following steps: in the heat flow measurement step, a first heat flow sensor configured to exchange heat with the device is used to measure the heat flow generated from the device, the resistance value of which is changed in a specified switching pattern, the switching pattern including a first pattern and a second pattern different from the first pattern; and in the estimation step, the power loss is estimated by comparing, among the heat flow measurement results, a first contribution which is the contribution of the heat flow due to the first pattern and a second contribution which is the contribution of the heat flow due to the second pattern.

(2) The method according to (1) above, wherein the first pattern is configured so that the state of the switching element changes in a first period, and the second pattern is configured so that the state of the switching element changes in a second period that is longer than the first period.

(3) In the method according to any one of (1) or (2) above, in the driving step, the device is driven based on the switching pattern.

(4) A method according to any one of the above (3), wherein in the driving step, the device is driven using the switching pattern in which the first pattern and the second pattern are superimposed, and in the estimation step, the first contribution and the second contribution are compared by extracting them from the measurement results.

(5) In the method according to any one of (1) to (4) above, the device further comprises a substrate, an element portion, and a housing, the element portion is formed on the substrate and includes the switching element, the housing is configured to cover the element portion together with the substrate, and further, in the first arrangement step, the first heat flow sensor is arranged to measure the heat flow from the element portion through the substrate, and in the heat flow measurement step, the first heat flow sensor is used to measure the heat flow from the element portion to the first heat flow sensor.

(6) The method according to (5) above, further comprising: in the induction step, using a heat insulating member or a heat conducting member, inducing the outflow heat from the element unit toward the housing to the first heat flow sensor; and in the heat flow measurement step, using the first heat flow sensor, measuring the heat flow from the element unit, including the induced outflow heat.

(7) A method according to the above (6), in which the induction step includes covering the element portion with a heat conductive member and connecting the heat conductive member to the first heat flow sensor or the substrate, thereby inducing the outflow heat to the first heat flow sensor via the heat conductive member.

(8) The method according to (6) or (7) above, wherein in the induction step, the outflow heat is induced to the first heat flow sensor by covering the element portion with a heat insulating material.

(9) A method according to any one of the above (5) to (8), wherein the estimation step further comprises estimating the power loss by comparing the measurement results of the heat flow in a physical model simulating the device with the measurement results of the first heat flow sensor.

(10) In the method according to any one of (5) to (9) above, the device further comprises a terminal for connecting the element portion to another element, and in the second placement step, a second heat flow sensor is placed on the terminal, and in the heat flow measurement step, the power due to the power loss is estimated based on the measurement result of the heat flow from the substrate by the first heat flow sensor and the measurement result of the heat flow from the terminal by the second heat flow sensor.

(11) A program for estimating power loss caused by a device including a switching element capable of changing a resistance value, the program causing a computer to execute each step of the method described in any one of (1) to (10) above.
Of course, this is not the case.

Furthermore, the following aspects may be provided independently of or in combination with the above aspects:

(Item 1)
A heating element;
a heat flow sensor provided in physical connection with the heating element;
A control device that estimates a heat loss in the heating element based on a signal acquired by the heat flow sensor;
A semiconductor system comprising:
(Other items)
The heat generating element is a semiconductor such as a power semiconductor, a CPU (for example, performing a switching process at a predetermined frequency), a DCDC converter, a power supply, or the like.
- Measure the thermal losses at multiple frequencies and then measure the difference followed by the switching losses.
・Measure the voltage and current values, and calculate the leakage current from the difference with the above switching loss.
A material with low thermal resistance, such as a heat sink, is provided between the heat flow sensor and the heating element.
The heating element and the heat flow sensor are connected via a solid material.
A heater is provided near the heating element, and the temperature of the outer surface of the heating element and the temperature of the space near the heating element are controlled to be constant.
- The heating element is covered with insulation material.
・The heating element is covered with a highly thermally conductive case, and the case is thermally coupled to the heat flow sensor.
- When there is a limb structure such as a footprint or lead extending from the heating element, the loss is calculated using the difference between the temperature of the heating element and the temperature of the limb structure, or the signal measured by a heat flow sensor installed in the limb structure.
The thermoelectric conversion elements of the heat flow sensor are Weyl magnets, Weyl semimetals, ferrimagnets, etc. The thickness of these elements is less than 1 micrometer.

Finally, various embodiments of the present disclosure have been described, but these are presented as examples and are not intended to limit the scope of the invention. The novel embodiments can be embodied in various other forms, and various omissions, substitutions, and modifications can be made without departing from the gist of the invention. The embodiments and modifications thereof are within the scope and gist of the invention, and are included in the scope of the invention and its equivalents as set forth in the claims.

1: Estimation system, 2: Semiconductor device, 21: Substrate, 22: Element section, 221: Switching element, 23: Housing, 24: Heat sink, 25: Guard heater, 26: Terminal, 3a: First heat flow sensor, 3b: Second heat flow sensor, 4: Measuring device, 5: Terminal, 50: Communication bus, 51: Communication section, 52: Memory section, 53: Processor, 54: Display section, 55: Input section, 6: Reference unit, 61: substrate, 62: heat generating part, 621: heat generating element, 63: housing, 64: heat sink, 7: reference heat flow sensor, PT1: first pattern, PT2: second pattern, T1: first cycle, T11: ON period, T12: first transition period, T13: OFF period, T14: second transition period, T2: second cycle, T21: ON period, T22: first transition period, T23: OFF period, T24: second transition period

Claims (11)

1. A method for estimating power loss through a device including a switching element with a variable resistance, comprising:
It includes the following steps:
In the heat flow measuring step, a first heat flow sensor configured to exchange heat with the device is used to measure a heat flow generated from the device in which the resistance value of the switching element is changed in a prescribed switching pattern;
the switching pattern includes a first pattern and a second pattern different from the first pattern,
A method in which, in the estimation step, the power loss is estimated by comparing a first contribution, which is a contribution of the heat flow due to the first pattern, with a second contribution, which is a contribution of the heat flow due to the second pattern, from the heat flow measurement results. 10. The method of claim 1 ,
The first pattern is configured such that the state of the switching element changes in a first period;
The second pattern is configured such that the switching element changes state over a second period that is longer than the first period. The method according to claim 1 or claim 2,
In the driving step, the device is driven based on the switching pattern. The method according to any one of claims 3,
In the driving step, the device is driven using the switching pattern obtained by superposing the first pattern and the second pattern;
A method according to claim 1, wherein the estimating step compares the first contribution with the second contribution by extracting the first contribution and the second contribution from the measurement result. The method according to any one of claims 1 to 4,
The device further includes a substrate, an element portion, and a housing.
the element section is formed on the substrate and includes the switching element,
the housing is configured to cover the element portion together with the substrate,
Furthermore, in the first placement step, the first heat flow sensor is placed so as to measure a heat flow from the element portion through the substrate;
The method, wherein the heat flow measuring step uses the first heat flow sensor to measure the heat flow from the element portion to the first heat flow sensor. 6. The method of claim 5,
Furthermore, in the induction step, a heat insulating member or a heat conductive member is used to induce the outflow heat from the element portion toward the housing to the first heat flow sensor,
The method according to claim 1, wherein the heat flow measuring step uses the first heat flow sensor to measure the heat flow from the element portion, including the induced outflow heat. 7. The method of claim 6,
In the induction step, the element portion is covered with a thermally conductive member, and the thermally conductive member is connected to the first heat flow sensor or the substrate, thereby inducing the outflow heat to the first heat flow sensor via the thermally conductive member. The method according to claim 6 or 7,
The method according to the present invention, wherein the inducing step includes covering the element portion with a heat insulating material to induce the outflow heat to the first heat flow sensor. The method according to any one of claims 5 to 8,
The method further includes, in the estimating step, estimating the power loss by comparing a measurement result of a heat flow in a physical model simulating the device with a measurement result of the first heat flow sensor. The method according to any one of claims 5 to 9,
the device further includes a terminal for connecting the element portion to another element;
Furthermore, in the second arranging step, a second heat flow sensor is arranged on the terminal;
A method in which, in the heat flow measuring step, the power due to the power loss is estimated based on the measurement result of the heat flow from the board by the first heat flow sensor and the measurement result of the heat flow from the terminal by the second heat flow sensor. A program for estimating power loss caused by a device including a switching element capable of changing a resistance value,
A program causing a computer to execute each step of the method according to any one of claims 1 to 10.

Images