JP2015206734A - Temperature calculating device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To calculate the temperature of a semiconductor element without arranging a temperature detection element on the semiconductor element.SOLUTION: A temperature calculating device that calculates the temperature of a semiconductor element includes: first calculating means that calculates the ringing amplitude which is included in the waveform of current or voltage at the time when the semiconductor element is switched between an on state and an off state; and second calculating means that calculates the temperature of the semiconductor element on the basis of the ringing amplitude.

Description

  The present invention relates to a temperature calculation device.

  2. Description of the Related Art Conventionally, a technique for measuring a temperature of a semiconductor element by arranging a temperature detection element on a semiconductor element and detecting a signal of the temperature detection element by a temperature detection circuit connected to the temperature detection element is known (for example, , See Patent Document 1).

JP 2009-254158 A

  However, in the above-described prior art, it is necessary to provide a pad on the semiconductor element in order to connect the temperature detection element and the temperature detection circuit. For this reason, the area of the region occupied by the pad in the semiconductor element increases, and the area of the active region through which current can flow decreases. For this reason, the area of a semiconductor element increases and the cost increases.

  Therefore, in one proposal of the present invention, the temperature of the semiconductor element is calculated without arranging the temperature detection element on the semiconductor element.

  In one proposal, there is provided a temperature calculation device for calculating a temperature of a semiconductor element, wherein a first amplitude calculating unit includes a ringing amplitude included in a current or voltage waveform when the semiconductor element is switched between an on state and an off state. There is provided a temperature calculation device including: a calculation means for calculating the temperature of the semiconductor element based on the ringing amplitude.

  According to one aspect, the temperature of the semiconductor element can be calculated without disposing the temperature detection element on the semiconductor element.

The figure which illustrates the circuit structure of the temperature calculation apparatus which concerns on this embodiment. The figure which illustrates the waveform of an electric current or a voltage when carrying out switching operation of the semiconductor element concerning this embodiment. The figure which illustrates the relationship between the temperature of the semiconductor element which concerns on this embodiment, and the drain-source voltage. The flowchart which illustrates the temperature calculation method by the temperature calculation apparatus which concerns on this embodiment. The figure which illustrates other circuit composition of the temperature calculation device concerning this embodiment. The figure which illustrates further another circuit composition of the temperature calculation device concerning this embodiment.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. In addition, in this specification and drawing, about the component which has the substantially same function structure, the duplicate description is abbreviate | omitted by attaching | subjecting the same code | symbol. In the following embodiments, a temperature calculation device that calculates the temperature of a semiconductor element constituting a switching circuit will be described as an example of a temperature calculation device. However, the present invention is not limited in this respect. For example, the temperature calculation device can be applied to a converter, a three-phase inverter circuit having a switching circuit as one arm, and the like.

  FIG. 1 is a diagram illustrating a circuit configuration of a temperature calculation device 2 according to this embodiment. As shown in FIG. 1, the temperature calculation device 2 according to the present embodiment is configured as a device that calculates the temperature of a semiconductor element constituting the switching circuit 1.

  Below, the structure and operation | movement of the switching circuit 1 are demonstrated first, and the structure and operation | movement of the temperature calculation apparatus 2 are demonstrated next.

  As shown in FIG. 1, the switching circuit 1 is configured such that, for example, switching elements Q1 and Q2 serving as two semiconductor elements connected in series are alternately turned on / off (switching operation), whereby a DC voltage is converted into an AC voltage. It functions as an inverter circuit that converts to.

  The switching circuit 1 includes a DC power supply 11, a smoothing capacitor 12 that stabilizes the power supply voltage, switching elements Q1 and Q2, and a feedback diode D1 having a forward direction from the ground to the power supply voltage (a direction from the drain to the source). , D2, a pulse power supply 13 for applying a pulsed voltage to the gate of the switching element Q1, a gate resistor 14 for adjusting the switching speed of the switching element Q1, and an inductive load 15 connected in parallel with the switching element Q2. Have

The switching element Q1 is a low-side (lower arm) switching element that is short-circuited to the ground (reference potential). The switching element Q2 is a high-side (upper arm) switching element that is short-circuited to the power supply voltage. As the switching elements Q1, Q2, for example, MOSFET (Metal Oxide Semiconductor Field Effect Transistor), IGBT (Insulated)
Gate Bipolar Transistor). As materials for the switching elements Q1 and Q2, for example, silicon (Si), silicon carbide (SiC), gallium nitride (GaN), or the like can be used. Therefore, SiC and GaN can be preferably used.

  Next, the operation of the switching circuit 1 will be described. FIG. 2 is a diagram illustrating a waveform of current or voltage when the semiconductor element constituting the switching circuit 1 is switched. FIG. 3 is a diagram illustrating the relationship between the temperature of the semiconductor element and the drain-source voltage Vds. In FIG. 3, the horizontal axis represents time, and the vertical axis represents the drain-source voltage Vds of the semiconductor element. In FIG. 3, a plurality of maximum values included in the waveform are referred to as peak values.

  Next, the operation of the switching circuit 1 will be described.

  When the switching element Q1 is in an off state and the switching element Q2 is in an on state, when a high-level gate voltage higher than the on voltage is applied to the gate of the switching element Q1 by the pulse power supply 13, the switching element in the off state Q1 is switched to the on state, and the switching element Q2 in the on state is switched to the off state.

  On the other hand, when the switching element Q1 is in the on state and the switching element Q2 is in the off state, when a low level gate voltage is applied to the gate of the switching element Q1 by the pulse power supply 13, the on state switching element Q1 is The switching element Q2 in the off state is switched to the on state.

  The switching circuit 1 performs a power conversion operation for converting a DC voltage into an AC voltage by alternately switching on and off the switching elements Q1 and Q2 by the pulse power supply 13.

  Here, when the power conversion operation is performed on the switching circuit 1 as described above, a switching waveform (hereinafter also referred to as a “waveform”) is generated as the switching elements Q1 and Q2 are turned on / off as shown in FIG. Ringing (indicated by solid circles in the figure) occurs at the rising or falling edge of the.

  Specifically, when the gate voltage Vg of the switching element Q1 applied by the pulse power supply 13 changes from the high level to the low level, the switching element Q1 is turned off (from the on state to the off state), and the switching element Q2 is turned on. Yes (from off to on). At this time, ringing occurs at the falling portion of the gate-source voltage Vgs of the switching element Q1, the rising portion of the drain-source voltage Vds, the falling portion of the drain current Id, and the falling portion of the diode current Idio of the feedback diode D2. Occur.

  Further, when the gate voltage Vg of the switching element Q1 applied by the pulse power supply 13 changes from the low level to the high level, the switching element Q1 is turned on (from the off state to the on state), and the switching element Q2 is turned off (on). State to off state). At this time, the rising part of the gate-source voltage Vgs of the switching element Q1 and the falling part of the drain current Id, the rising part of the drain-source voltage Vds of the switching element Q2, and the rising part of the diode current Idio of the feedback diode D2 Ringing (indicated by broken circles in the figure) occurs.

  As shown in FIG. 3, the amplitude of ringing (hereinafter also referred to as “ringing amplitude”) varies depending on the temperature of a conducting element (hereinafter also referred to as “conducting element”). That is, when the temperature of the semiconductor element is different from 25 ° C. (indicated by a solid line in the figure), 125 ° C. (indicated by a broken line in the figure), and 175 ° C. (indicated by a dotted line in the figure), the ringing amplitude changes. To do. For example, the ringing amplitude in the waveform of the drain-source voltage Vds of the semiconductor element decreases as the temperature of the semiconductor element increases (see arrows in the figure).

  Table 1 shows the relationship between the timing at which ringing occurs in each current or voltage waveform shown in FIG. 2 and the conductive element at that time.

表１に示すように、スイッチング素子Ｑ１がオフする場合には、帰還ダイオードＤ１が導通していることから、リンギング振幅は帰還ダイオードＤ１の温度によって変化する。また、スイッチング素子Ｑ１がオンする場合には、スイッチング素子Ｑ１が導通していることから、リンギング振幅はスイッチング素子Ｑ１の温度によって変化する。

As shown in Table 1, when the switching element Q1 is turned off, since the feedback diode D1 is conductive, the ringing amplitude varies depending on the temperature of the feedback diode D1. When the switching element Q1 is turned on, since the switching element Q1 is conductive, the ringing amplitude varies depending on the temperature of the switching element Q1.

  Next, the configuration of the temperature calculation device 2 will be described with reference to FIG.

  The temperature calculation device 2 includes: a first calculation unit that calculates a ringing amplitude included in a current or voltage waveform when the semiconductor element switches between an on state and an off state; and the semiconductor element based on the ringing amplitude. Second calculating means for calculating the temperature.

  The first calculating means calculates a ringing amplitude included in a waveform when the semiconductor element is switched between an on state and an off state. The first calculation means includes AC component extraction means 21, rectification means 22, smoothing means 23, and peak hold 24. A load 25 is connected to the first calculation means.

  The alternating current component extracting means 21 extracts a waveform including a direct current component (DC component) and an alternating current component (AC component) when the semiconductor element is switched between the on state and the off state. Although it does not specifically limit as AC component extraction means 21, For example, the circuit etc. which contain a capacitor | condenser are mentioned.

  The rectifier 22 rectifies the waveform from which only the AC component is extracted. The rectifier 22 is not particularly limited, and examples thereof include a half-wave rectifier circuit including a diode and a full-wave rectifier circuit.

  The smoothing means 23 smoothes the rectified waveform. Although it does not specifically limit as the smoothing means 23, For example, the smoothing circuit containing a capacitor | condenser, the smoothing circuit containing a coil, etc. are mentioned.

  The peak hold 24 holds the largest value in the smoothed waveform after a predetermined time has passed. The peak hold 24 is not particularly limited, and examples thereof include a circuit including a comparator.

  The second calculation means calculates the temperature of the semiconductor element based on the ringing amplitude calculated by the first calculation means. Although it does not specifically limit as a 2nd calculation means, For example, the structure etc. which contain CPU and a memory | storage means are mentioned.

  Next, operation | movement of the temperature calculation apparatus 2 which concerns on this embodiment is demonstrated. Hereinafter, as an example, a case will be described in which the temperature of the switching element Q1 is calculated based on the ringing amplitude included in the waveform of the rising portion of the drain current Id of the switching element Q1 included in the switching circuit 1. The invention is not limited in this respect.

  FIG. 4 is a flowchart illustrating a temperature calculation method by the temperature calculation apparatus 2 according to this embodiment. Hereinafter, steps S1 to S5 will be described with reference to FIG. In FIG. 4, the waveform shown on the right side of steps S1 to S4 is an outline of the waveform in each of steps S1 to S4.

(S1) Extraction of AC component only The AC component extraction means 21 is a drain current Id that includes a DC component and an AC component when a semiconductor element detected by, for example, a detection circuit including a diode switches between an on state and an off state. Only the AC component is extracted from the waveform of the rising portion.

(S2) Rectification The rectification means 22 rectifies the waveform from which only the AC component is extracted. FIG. 4 shows a case where the waveform is half-wave rectified.

(S3) Smoothing The smoothing means 23 smoothes the rectified waveform.

(S4) Peak hold The peak hold 24 holds the largest value in the smoothed waveform after a predetermined time has passed. Here, the predetermined time is preferably set in accordance with detected parameters (for example, drain current Id, diode current Idio, drain-source voltage Vds). The predetermined time is the time after the time when the first peak value is detected in the waveform from which only the AC component is extracted, and is the time when the second peak value is detected. It is preferable to set the time before elapses. The method for setting the predetermined time is not particularly limited, but is set by, for example, a gate signal.

(S5) Calculation of Temperature of Semiconductor Element The second calculation means calculates the temperature of the switching element Q1 based on the ringing amplitude calculated by the first calculation means. Specifically, the second calculation means, for example, the relationship between the temperature of the switching element Q1 stored in advance in the storage means and the ringing amplitude included in the waveform of the rising portion of the drain current Id, and the first calculation Based on the ringing amplitude calculated by the means, the temperature of the switching element Q1 is calculated.

  With the above steps, the operation of the temperature calculation device 2 is completed.

  As described above, according to the temperature calculation device 2 according to the present embodiment, the first calculation unit that calculates the ringing amplitude included in the waveform when the semiconductor element switches between the on state and the off state; Second calculating means for calculating the temperature of the semiconductor element based on the ringing amplitude.

  For this reason, the temperature of a semiconductor element is computable, without arrange | positioning a temperature detection element on a semiconductor element. Further, it is not necessary to provide a pad on the semiconductor element for connecting the temperature detection circuit and the temperature detection circuit that is connected to the temperature detection element and detects a signal of the temperature detection element. For this reason, the area of the active region through which a current in the semiconductor element can flow increases. As a result, the semiconductor element can be reduced in size, high integration can be achieved, and cost can be reduced.

  In the present embodiment, the temperature of the feedback diode D1 is calculated by changing the calculation target in the operation of the temperature calculation device 2 described above from the rising waveform of the drain current Id to the falling waveform of the drain current Id. can do. That is, the temperature calculation device 2 can calculate the temperature of the feedback diode D1 based on the ringing amplitude included in the waveform of the falling portion of the drain current Id.

  Next, a modification of this embodiment will be described.

  FIG. 5 is a diagram illustrating another circuit configuration of the temperature calculation device 2 according to this embodiment. As shown in FIG. 5, the temperature calculation device 2 calculates the temperatures of the switching element Q1 and the feedback diode D1 based on the waveform of the diode current Idio of the feedback diode D2, and thus the temperature calculation device according to the above-described embodiment. 2 and different.

  That is, the temperature calculation device 2 shown in FIG. 5 includes first calculation means for calculating a ringing amplitude included in the waveform of the diode current Idio when the semiconductor element is switched between the on state and the off state, and the ringing amplitude. And a second calculating means for calculating the temperature of the semiconductor element.

  According to the temperature calculation device 2 shown in FIG. 5, the same operation and effect as the temperature calculation device 2 shown in FIG. 1 described above can be obtained.

  In addition, the temperature calculation device 2 according to the present embodiment can calculate the temperature of the feedback diode D1 based on the waveform of the drain-source voltage Vds of the switching element Q1, as shown in FIG. 6, for example. Since the calculation method is the same as the operation of the temperature calculation device 2 described above, description thereof is omitted.

  As described above, the temperature calculation device 2 has been described with the embodiment, but the present invention is not limited to the above embodiment, and various modifications and improvements can be made within the scope of the present invention.

  For example, the temperature calculation device 2 may be configured to calculate the temperature of the semiconductor element based on the gate-source voltage Vgs of the switching element Q1 and the drain-source voltage Vka of the switching element Q2.

DESCRIPTION OF SYMBOLS 1 Switching circuit 2 Temperature calculation apparatus 21 AC component extraction means 22 Rectification means 23 Smoothing means 24 Peak hold Q1, Q2 Switching element

Claims (6)

A temperature calculation device for calculating the temperature of a semiconductor element,
First calculating means for calculating a ringing amplitude included in a current or voltage waveform when the semiconductor element is switched between an on state and an off state;
Second calculating means for calculating the temperature of the semiconductor element based on the ringing amplitude;
Temperature calculation device. The first calculation means includes
AC component extraction means for extracting a waveform of only the AC component from the waveform of the current or voltage including a DC component and an AC component;
Rectifying means for rectifying the waveform from which only the AC component is extracted;
Smoothing means for smoothing the rectified waveform;
A peak hold for holding the largest value constant in the smoothed waveform after a lapse of a predetermined time after the semiconductor element is switched between an on state and an off state;
Calculating the ringing amplitude based on the largest value in the waveform held by the peak hold;
The temperature calculation apparatus according to claim 1. The predetermined time is the time after the time when the first peak value is detected in the waveform from which only the AC component is extracted, and is the time when the second peak value is detected. Set to be the time before the lapse,
The temperature calculation apparatus according to claim 2. A detector circuit for detecting a waveform of a current or a voltage when the semiconductor element is switched between an on state and an off state;
The temperature calculation apparatus as described in any one of Claims 1 thru | or 3.   The temperature calculation device according to any one of claims 1 to 4, wherein the semiconductor element is a switching element that forms an inverter circuit. The semiconductor element includes silicon carbide.
The temperature calculation apparatus as described in any one of Claims 1 thru | or 5.

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