Semiconductor device and overcurrent protection method thereof

Abstract

The present invention provides a semiconductor device and an overcurrent protection method thereof, which achieves high-precision switching element protection. The device comprises: a chip temperature detection diode 8 for the switching element 2; a control circuit temperature detection diode 3, which is disposed in the control circuit that controls the switching element 2; and an overcurrent reference voltage correction circuit 4, which compares the detection potentials of the two, corrects the overcurrent reference voltage generated by the overcurrent reference voltage circuit 5, and outputs the corrected overcurrent reference voltage.

Description

Technical Field

[0001] The present invention relates to a power semiconductor device, and more particularly to a protection method in a module having a control circuit and a switching element such as an IGBT. Background Art

[0002] Conventionally, there is known a structure in which power switching elements such as transistors, IGBTs (Insulated Gate Bipolar Transistors), and MOSFETs (Metal-Oxide-Semiconductor Field-Effect Transistors) are modularized (hereinafter referred to as a switching element module).

[0003] These switching element modules have various protection functions, one of which is an overcurrent protection function.

[0004] The overcurrent protection function is composed of a chip temperature detection diode attached to the switching element and an IC that performs the protection operation. The chip temperature detection diode is sometimes integrated with the switching element (for example, see Patent Document 1), sometimes separated from the switching element and provided on the same circuit board, and sometimes provided in the same resin case as the switching element (for example, see the second embodiment of Patent Document 2, which is attached to this specification). Figure 24 (The second embodiment is shown in FIG. 1 ). Here, the circuit board has a predetermined circuit pattern and is an insulating substrate on which electronic components are mounted.

[0005] Figure 18 This is a diagram showing an example of the internal structure of a conventional IPM (Intelligent Power Module), which is a type of switching element module.

[0006] About this Figure 18 The IPM 300 shown in the figure forms an inverter that outputs a three-phase AC voltage. Therefore, IPM 300 has a positive power supply terminal P, a negative power supply terminal N, and output terminals U, V, and W, and incorporates six IGBTs 301 to 306. IGBTs 301 to 306 are connected in antiparallel via protective diodes 311 to 316 mounted on the same circuit pattern. Between the positive power supply terminal P and the negative power supply terminal N, IGBT 301 and IGBT 302 are connected in series, IGBT 303 and IGBT 304 are connected in series, and IGBT 305 and IGBT 306 are connected in series, forming three arm pairs. Furthermore, the intermediate connection points of the U, V, and W phase arms are connected to the output terminals U, V, and W, respectively (Patent Document 1).

[0007] IGBTs 301-306 have a temperature detection diode with a PN junction formed in the center of their respective surfaces (emitter terminals) via an insulating layer. This allows IGBTs 301-306 to observe chip temperatures close to their junction temperatures by monitoring the temperature-dependent forward voltage of the temperature detection diodes.

[0008] The gate terminals and temperature detection diodes of the IGBTs 301 to 306 are connected to the control ICs 321 to 326. The control ICs 321 to 326 control the switching of the IGBTs 301 to 306 and detect overheating of the IGBTs 301 to 306 by passing a constant current through the temperature detection diodes.

[0009] Figures 19 to 24 A semiconductor element module as a type of switching element module and a module unit formed by combining a plurality of these semiconductor element modules are shown. Figure 19 This is a bird's-eye view of the internal structure of semiconductor device module 500. An insulating substrate 403 is provided on a bottom metal substrate 409. An emitter pattern 404 and a collector pattern 405 are provided on insulating substrate 403. An IGBT 401 and a diode element 402 are further provided on the emitter pattern 404 and the collector pattern 405. Metal wires 407 electrically couple the IGBT to a gate pattern 406 and a control emitter pattern 408. In this structure, a gate terminal 413 and a control emitter terminal 414 are connected to the gate pattern 406 and the control emitter pattern 408. Figure 20 This is a diagram showing the semiconductor element module 500 as viewed from the top. Figure 21 It is from Figure 20 The diagram is observed by arrow A. Figure 20 and Figure 21 The structure is obtained as follows: Figure 19 The internal structure shown is formed in a resin case 410, and a main emitter terminal 411 and a main collector terminal 412 are provided on the emitter pattern 404 and the collector pattern 405, respectively. Figure 22 1 is a diagram showing a module unit composed of eight semiconductor element modules 500. Figure 23 Observed from arrow A Figure 22 Although there are IGBT 401, semiconductor element module 500 including the IGBT 401, and control substrate 420, control substrate 420 is mounted outside semiconductor element module 500. 501 and 502 are unit frames. Figure 24 In the second embodiment, a thermistor 432 for detecting the temperature inside the semiconductor element module 600 is provided on the insulating relay substrate 431 and is covered with a resin case (Patent Document 2).

[0010] In the following description of the drawings, the same or similar parts are denoted by the same or similar reference numerals. In addition, the maximum value of the operating temperature preset in the power semiconductor device is denoted by TH, and the minimum value is denoted by TL.

[0011] Figure 13 FIG2 shows an example of a conventional power semiconductor device. The device includes a control circuit 1, a switching element 2, and a switching element temperature detection diode 8. The control circuit 1 includes an overcurrent reference voltage circuit 5a, an overcurrent detection comparator 6, a sense voltage detection resistor 7, an overheat detection comparator 9, an overheat reference voltage circuit 10, and a filter 13.

[0012] like Figure 13 As shown, the control circuit 1 is connected to the switching element 2. That is, the control circuit 1 includes an output terminal OUT for outputting a gate voltage, an overcurrent detection terminal OC, and an overheat detection terminal OH.

[0013] The output terminal OUT is connected to the gate terminal of the switching element 2, and the overcurrent detection terminal OC is connected to the current sensing emitter terminal of the switching element 2. The emitter terminal of the switching element 2 is connected to the ground potential.

[0014] Within the control circuit 1, the overheat detection terminal OH is connected to a constant current source 11 and the inverting input terminal of an overheat detection comparator 9. The non-inverting input terminal of the overheat detection comparator 9 is connected to an overheat reference voltage circuit 10. The overheat detection terminal OH is connected to the anode terminal of the switching element temperature detection diode 8. The cathode terminal of the switching element temperature detection diode 8 is connected to the ground potential.

[0015] A constant current generated by a constant current source 11 constantly flows through the switching element temperature detection diode 8, and a forward voltage corresponding to the chip temperature of the switching element 2 is applied to the inverting input terminal of the overheat detection comparator 9. Assuming that the temperature characteristic of the switching element temperature detection diode 8 has a negative temperature characteristic, the overheat reference voltage circuit 10 outputs an overheat reference voltage VOH1 corresponding to the temperature TH. Consequently, when the chip temperature is below TH, the overheat detection comparator 9 outputs a low-level protection activation signal. If the chip temperature rises above TH, the overheat detection comparator 9 outputs a high-level protection activation signal. When this high-level protection activation signal is output, the control circuit 1 simultaneously controls the switching element 2 to turn off while outputting an alarm signal from the alarm output circuit.

[0016] Within control circuit 1, overcurrent detection terminal OC is connected to sense voltage detection resistor 7 and the inverting input terminal of overcurrent detection comparator 6. The non-inverting input terminal of overcurrent detection comparator 6 is connected to overcurrent reference voltage circuit 5a. The output of overcurrent detection comparator 6 is connected to the input of filter 13, which removes components other than the voltage proportional to the collector current.

[0017] Generally, as a method for detecting overcurrent, the following method is known: a current of about one ten-thousandth of the emitter current is diverted from the switching element 2, and a voltage (sense voltage) obtained by passing the current through the sensing voltage detection resistor 7 is compared with the overcurrent reference voltage VOC generated by the overcurrent reference voltage circuit 5a of the overcurrent detection comparator 6, thereby detecting the current, and judging the magnitude of the current based on the magnitude of the sense voltage, and then issuing an alarm output and / or gate cut-off through the protection operation credit logic circuit.

[0018] Figure 15 2 shows the process of overcurrent detection and judgment. As shown by line 201, the relationship between the collector current and the sense voltage is such that the higher the collector current, the higher the sense voltage. The sense voltage is compared with a predetermined reference voltage value VB. If the sense voltage exceeds the reference voltage value VB, it is considered that the collector current value IC at the intersection of the two values ​​has been exceeded, and an overcurrent is determined.

[0019] The higher the temperature of the switching element 2 , the higher the sense voltage, and the higher the temperature of the control circuit, the higher the current detection voltage.

[0020] Figure 16 202 is the sense voltage at temperature TH, and 204 is the sense voltage at temperature TL. VBH is the reference voltage at temperature TH, and VBL is the reference voltage at temperature TL.

[0021] Typically, the temperature of the switching element is substantially the same as the temperature of the control circuit, or the temperature of the switching element is slightly higher.

[0022] Therefore, if Figure 16 As shown, when both temperatures are TH, the sense voltage is represented by line 202. Since the reference voltage is VBH, the overcurrent protection value is at the intersection 203 of the two. The range of collector current ICTH or above falls within the overcurrent protection range. Similarly, when both temperatures are TL, the sense voltage is represented by line 204. Since the reference voltage is VBL, the overcurrent protection value is at the intersection 205 of the two. The range of collector current ICTL or above falls within the overcurrent protection range.

[0023] Prior art literature

[0024] Patent Literature

[0025] Patent Document 1: WO2016 / 039342

[0026] Patent Document 2: Japanese Patent Application Laid-Open No. 2002-184940 Summary of the Invention

[0027] Technical issues

[0028] The temperature of the switching element and the control circuit may differ significantly. In particular, when the control circuit is located outside the switching element as described in Patent Document 2, heat generated in one of the switching element and the control circuit may not be fully transferred to the other.

[0029] When the temperature of the switching element is extremely higher than the temperature of the control circuit, the overcurrent protection value calculated using the conventional technology becomes lower than the originally required value, and thus excessive protection is performed.

[0030] For example, when the switching element is at temperature TH and the control circuit is at temperature TL, the intersection 206 of sense voltage 202 and reference voltage VBL is set as the overcurrent value, and the collector current range above ICmin becomes the overcurrent protection range. However, considering the switching element temperature, the range above ICTH is the overcurrent protection range, and unnecessary protection is applied to the collector current range from ICmin to ICTH.

[0031] Therefore, in the prior art, the overcurrent protection range has a redundant area shown as 207 .

[0032] The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to provide a semiconductor device and its protective function with high precision in protecting a switching element.

[0033] Technical Solution

[0034] In order to solve the above-mentioned problems, the main purpose is to have: a switching element; a control circuit that controls the switching element and has an overcurrent protection function; and temperature detection units separately set for the switching element and the control circuit; and to correct the overcurrent detection reference based on two detection values ​​detected by the temperature detection units on both sides.

[0035] The switching element may be mounted on a circuit substrate formed of an insulating substrate having a predetermined circuit pattern and on which electronic components are mounted, and the control circuit may also be mounted on a circuit substrate formed of an insulating substrate having a predetermined circuit pattern and on which electronic components are mounted. The switching element and the control circuit may be mounted on the same circuit substrate.

[0036] The switch element may be molded with a resin case to cover the switch element, and the control circuit may also be molded with a resin case to cover the switch element. The switch element and the control circuit may also be mounted in the same resin case.

[0037] The temperature measuring unit of the switching element is provided in the same element, or is provided on a circuit board on which the switching element is mounted, or in a resin case housing the switching element, or near the resin case housing the switching element, at a position where the temperature of the switching element can be measured.

[0038] In addition, the temperature measuring unit of the control circuit is arranged in the same control circuit, or the temperature measuring unit of the control circuit is arranged on the circuit substrate on which the control circuit is mounted, or in the resin case in which the control circuit is housed, or near the resin case in which the control circuit is housed, at a position where the temperature of the control circuit can be measured.

[0039] MOSFET or IGBT can be used as the switching element, and a diode can be used as the temperature detection unit.

[0040] When a unit having negative temperature characteristics such as a diode is used as the temperature detection unit, the circuit serving as a reference for correcting overcurrent detection can discriminate the detection voltage obtained by the temperature detection unit of the switching element according to multiple levels, set the converted voltage to the same number of multiple levels, and convert it into an output voltage in which the magnitude relationship of the detection voltage is reversed, and output a value calculated based on the sum of the output voltage and the detection voltage obtained by the temperature detection unit of the control circuit as the overcurrent detection reference value.

[0041] In addition, when a unit with a positive temperature characteristic is used for the temperature detection unit, the circuit serving as a correction overcurrent detection reference can discriminate the detection voltage obtained by the temperature detection unit of the control circuit according to multiple levels, and further set the converted voltage to multiple levels of the same number, and convert it into an output voltage in which the magnitude relationship of the detection voltage is reversed, and output a value calculated based on the sum of the output voltage and the detection voltage obtained by the temperature detection unit of the switching element as the overcurrent detection reference value.

[0042] Alternatively, in the case where a unit having a negative temperature characteristic is used for each of the temperature detection units of the switching element and the control circuit, the circuit serving as a correction for the overcurrent detection reference can convert the detection voltage obtained by the temperature detection unit of the switching element into an output voltage in which the magnitude relationship of the detection voltage is reversed, and output a value calculated based on the sum of the output voltage and the detection voltage obtained by the temperature detection unit of the control circuit as the overcurrent detection reference value.

[0043] In addition, when a unit with a positive temperature characteristic is used for each of the temperature detection units of the switching element and the control circuit, the circuit serving as a correction for the overcurrent detection reference can convert the detection voltage obtained by the temperature detection unit of the control circuit into an output voltage in which the magnitude relationship of the detection voltage is reversed, and output a value calculated based on the sum of the output voltage and the detection voltage obtained by the temperature detection unit of the switching element as the overcurrent detection reference value.

[0044] In addition, when a unit with positive temperature characteristics is used for the temperature detection unit of the switching element and a unit with negative temperature characteristics is used for the temperature detection unit of the control circuit, the circuit used to correct the overcurrent detection reference can output a value calculated based on the sum of the detection voltages obtained by the two temperature detection units as the overcurrent detection reference value.

[0045] Effects of the Invention

[0046] According to the present invention, by correcting the overcurrent protection detection level, the redundant range of the overcurrent protection can be reduced, and the overcurrent protection function can be made more accurate. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] Figure 1 This is a block diagram showing a first embodiment of the power semiconductor device according to the present invention.

[0048] Figure 2 This is a circuit diagram showing a first example of the overcurrent reference voltage correction circuit of the present invention.

[0049] Figure 3 This is a diagram showing an example of the relationship between T1 and T2, inputs VF1 and VF2, and correction value VOCa in the first example of the overcurrent reference voltage correction circuit of the present invention.

[0050] Figure 4 This is a diagram showing an example of the relationship between T1 and T2 and inputs VF1 and VF2 , a reference voltage VOCo before correction, and an output VOC in the first example of the overcurrent reference voltage correction circuit of the present invention.

[0051] Figure 5 1 is a circuit diagram showing a second example of the overcurrent reference voltage correction circuit of the present invention.

[0052] Figure 6 1 is a circuit diagram showing a third example of the overcurrent reference voltage correction circuit of the present invention.

[0053] Figure 7 This is a diagram showing an example of the relationship between T1 and T2, inputs VF1 and VF2, and correction value VOCa in the third example of the overcurrent reference voltage correction circuit of the present invention.

[0054] Figure 8 This is a diagram showing an example of the relationship between T1 and T2 and inputs VF1 and VF2 , a reference voltage VOCo before correction, and an output VOC in the third example of the overcurrent reference voltage correction circuit of the present invention.

[0055] Figure 9 1 is a circuit diagram showing a fourth example of the overcurrent reference voltage correction circuit of the present invention.

[0056] Figure 10 1 is a circuit diagram showing a fifth example of the overcurrent reference voltage correction circuit of the present invention.

[0057] Figure 11 This is a diagram showing an example of the relationship between T1, T2, inputs VF1, VF2, and correction value VOCa in the first example of the overcurrent reference voltage correction circuit of the present invention. Figure 3 ) is expanded to the range of T2>T1.

[0058] Figure 12 This is a diagram showing an example of the relationship between T1, T2, inputs VF1, VF2, the reference voltage VOCo before correction, and the output VOC of the first example of the overcurrent reference voltage correction circuit of the present invention. Figure 4 ) is expanded to the range of T2>T1.

[0059] Figure 13 This is a block diagram showing an example of a conventional power semiconductor device.

[0060] Figure 14 This is a block diagram showing a second embodiment of the power semiconductor device according to the present invention.

[0061] Figure 15 This is a diagram showing an operating range of overcurrent protection for a power semiconductor device.

[0062] Figure 16 This is a diagram showing a redundant region of overcurrent protection operation in a conventional power semiconductor device.

[0063] Figure 17 This is a diagram showing a redundant region of an overcurrent protection operation in a power semiconductor device according to an embodiment of the present invention.

[0064] Figure 18 This is a diagram showing an example of the internal structure of a conventional switching element module (IPM).

[0065] Figure 19 This is a diagram showing an example of the internal structure of a conventional semiconductor element module in which a semiconductor element and a control circuit are separated.

[0066] Figure 20 This is a diagram showing an example of the internal structure of a conventional semiconductor element module in which a semiconductor element and a control circuit are separated.

[0067] Figure 21 This is a diagram showing an example of the internal structure of a conventional semiconductor element module in which a semiconductor element and a control circuit are separated.

[0068] Figure 22 This is a diagram showing an example of a conventional module unit in which a semiconductor element and a control circuit are separated.

[0069] Figure 23 This is a diagram showing an example of a conventional module unit in which a semiconductor element and a control circuit are separated.

[0070] Figure 24 This is a diagram showing an example of the internal structure of a conventional semiconductor element module in which a semiconductor element and a control circuit are separated and a temperature detection unit is provided.

[0071] Explanation of symbols

[0072] 1…Control circuit

[0073] 2…Switching element

[0074] 2a…Switching element

[0075] 3…Diode for temperature detection of control circuit

[0076] 4…Overcurrent reference voltage correction circuit

[0077] 5…Overcurrent reference voltage circuit

[0078] 5a…Conventional overcurrent reference voltage circuit

[0079] 6…Overcurrent detection comparator

[0080] 7…Resistor for sensing voltage detection

[0081] 8…Diode for detecting switching element temperature

[0082] 9…Overheat detection comparator

[0083] 10…Overheat reference voltage circuit

[0084] 11, 12…Constant current source

[0085] 13…Filter

[0086] 101…Digital Circuits (Level 3)

[0087] 101a…Digital Circuits (Level 4)

[0088] 102-103, 102a, 103a...comparator

[0089] 104, 105, 104a, 105a… switches

[0090] 106~112, 123~126, 133~136, 106a, 110a...resistors

[0091] 121, 131…Differential amplifier circuit

[0092] 201…Sense voltage for collector current

[0093] 202…Sensor voltage when the switching element temperature is TH

[0094] 203... Overcurrent protection value when the temperature of the switching element and the control circuit are both TH

[0095] 204…Sensing voltage when the switching element temperature is TL

[0096] 205...Overcurrent protection value when the temperature of the switching element and the control circuit are both TL

[0097] 206…In the previous design, the overcurrent protection value when the switching element temperature is TH and the control circuit temperature is TL

[0098] 207…Redundant range of overcurrent protection in previous designs

[0099] 208 ... Redundancy range of overcurrent protection for power semiconductor devices according to embodiments of the present invention

[0100] 301~306…IGBT

[0101] 311~316…Protection diode

[0102] 321~326…control circuit

[0103] 401…IGBT components

[0104] 402…Diode element

[0105] 403…Insulation substrate

[0106] 404…Emitter pattern

[0107] 405…Collector pattern

[0108] 406…Gate pattern

[0109] 407…metal wire

[0110] 408…Control emitter pattern

[0111] 409…Bottom metal substrate

[0112] 410…resin shell

[0113] 411…Main emitter terminal

[0114] 412…Main collector terminal

[0115] 413…Gate terminal

[0116] 414…Control emitter terminal

[0117] 420…Control board

[0118] 431…Relay insulation substrate

[0119] 435…Thermistor

[0120] 500, 600...Semiconductor device modules

[0121] 501, 502…unit frame DETAILED DESCRIPTION

[0122] like Figure 1 As shown, the first embodiment of the power semiconductor device of the embodiment of the present invention has a control circuit 1, a switching element 2 and a diode 8 for detecting the temperature of the switching element. The switching element 2 shows an example of using an IGBT in this embodiment. The diode 8 for detecting the temperature of the switching element may also be built into the switching element 2. In the case where the switching element 2 is an IGBT, the diode 8 for detecting the temperature of the switching element 2 is formed of polysilicon through an insulating film in the center of the surface (emitter terminal) of the switching element 2. In addition, the diode 8 for detecting the temperature of the switching element 2 may also be configured separately from the switching element 2 at a position where the temperature of the switching element 2 can be measured. For example, the diode 8 for detecting the temperature of the switching element 2 may be mounted on a circuit substrate on which the switching element 2 is mounted, or may be configured in the same resin housing as the switching element 2, or may be configured near a resin housing on which the switching element 2 is molded. Here, the circuit substrate is an insulating substrate having a predetermined circuit pattern.

[0123] The control circuit 1 includes a temperature detection diode 3 for the control circuit, an overcurrent reference voltage correction circuit 4, an overcurrent reference voltage circuit 5, an overcurrent detection comparator 6, a sense voltage detection resistor 7, an overheat detection comparator 9, an overheat reference voltage circuit 10, constant current sources 11 and 12, and a filter 13. The control circuit 1 and the temperature detection diode 3 for the control circuit can also be integrated into the same semiconductor substrate. For example, the temperature detection diode 3 is formed of polycrystalline silicon on the surface of the semiconductor substrate with an insulating film interposed therebetween. Alternatively, the temperature detection diode 3 can be arranged separately from the control circuit 1 at a position where the temperature of the control circuit 1 can be measured. For example, the temperature detection diode 13 can be mounted on the circuit substrate on which the control circuit 1 is mounted, or can be arranged in the same resin case as the control circuit 1, or can be arranged near the resin case in which the control circuit 1 is molded.

[0124] like Figure 1 As shown, the control circuit 1 is connected to the switching element 2. The switching element 2 also has a built-in current sensing element in parallel with the IGBT, through which the main current flows. The control circuit 1 includes an output terminal OUT, which outputs a gate voltage, an overcurrent detection terminal OC, and an overheat detection terminal OH. Furthermore, the control circuit 1 and the switching element 2, including the control circuit temperature detection diode 3 and the switching element temperature detection diode 8, can be provided on the same circuit board or in the same resin case, or they can be molded separately.

[0125] The output terminal OUT is connected to the gate terminal of the switching element 2, and the overcurrent detection terminal OC is connected to the current sensing terminal of the current sensing element of the switching element 2. The emitter terminal of the switching element 2 is connected to the ground potential.

[0126] Within the control circuit 1, the overheat detection terminal OH is connected to a constant current source 11, the inverting input terminal of the overheat detection comparator 9, and the overcurrent reference voltage correction circuit 4. The non-inverting input terminal of the overheat detection comparator 9 is connected to the overheat reference voltage circuit 10. The overheat detection terminal OH is connected to the anode terminal of the switching element temperature detection diode 8, and the cathode terminal of the switching element temperature detection diode 8 is connected to the ground potential of the control circuit 1.

[0127] A constant current generated by a constant current source 11 constantly flows through the switching element temperature detection diode 8, and a forward voltage corresponding to the chip temperature of the switching element 2 is applied to the inverting input terminal of the overheat detection comparator 9. Assuming that the switching element temperature detection diode 8 has a negative temperature characteristic, the overheat reference voltage circuit 10 outputs an overheat reference voltage VOH1 corresponding to the temperature TH. Consequently, when the chip temperature is below TH, the overheat detection comparator 9 outputs a low-level protection activation signal. If the chip temperature rises above TH, the overheat detection comparator 9 outputs a high-level protection activation signal. When this high-level protection activation signal is output, the control circuit 1 simultaneously outputs an alarm signal from the alarm output circuit and controls the switching element 2 to turn off.

[0128] Within the control circuit 1, the overcurrent detection terminal OC is connected to the sense voltage detection resistor 7 and the inverting input terminal of the overcurrent detection comparator 6. The non-inverting input terminal of the overcurrent detection comparator 6 is connected to the overcurrent reference voltage correction circuit 4. The output of the overcurrent detection comparator 6 is connected to the input of the filter 13, which removes components other than the voltage proportional to the collector current.

[0129] A constant current generated by a constant current source 12 always flows through the temperature detection diode 3 of the control circuit, and a forward voltage corresponding to the temperature of the control circuit 1 is applied as VF2 to the overcurrent reference voltage correction circuit 4 .

[0130] The overcurrent reference voltage correction circuit 4 calculates a correction value VOCa for the overcurrent reference voltage VOCo output from the overcurrent reference voltage circuit 5 based on the signal VF1 obtained from the switching element temperature detection diode 8 and the signal VF2 obtained from the temperature detection diode 3 of the above-mentioned control circuit, and sends the corrected overcurrent reference voltage VOC to the non-inverting input terminal of the comparator 6.

[0131] The overcurrent detection comparator 6 compares a sense voltage obtained by diverting about one ten-thousandth of the emitter current of the switching element 2 and passing the current through the sense voltage detection resistor 7 with an overcurrent reference voltage VOC and sends a protection operation signal.

[0132] like Figure 14As shown, a second embodiment of a power semiconductor device according to an embodiment of the present invention includes a control circuit 1, a switching element 2a, and a switching element temperature detection diode 8. In this embodiment, the switching element 2a is an example of a MOSFET. The switching element 2a and the switching element temperature detection diode 8 can be formed integrally as a single chip, or can be provided within the same circuit substrate or resin housing. Alternatively, the switching element temperature detection diode 8 can be provided near the resin housing in which the switching element 2a is molded, at a location where the switching element temperature can be measured. Here, the circuit substrate is an insulating substrate having a predetermined circuit pattern and on which electronic components are mounted.

[0133] The control circuit 1 includes a control circuit temperature detection diode 3, an overcurrent reference voltage correction circuit 4, an overcurrent reference voltage circuit 5, an overcurrent detection comparator 6, a sense voltage detection resistor 7, an overheat detection comparator 9, an overheat reference voltage circuit 10, constant current sources 11 and 12, and a filter 13. The control circuit 1 and the control circuit temperature detection diode 3 may be formed integrally as a single chip, provided within the same circuit substrate or resin casing, or provided near the resin casing in which the control circuit 1 is molded, at a location where the control circuit temperature can be detected.

[0134] like Figure 14 As shown, control circuit 1 is connected to switching element 2a. Switching element 2 also incorporates a current sensing element in parallel with the MOSFET through which the main current flows. Control circuit 1 includes an output terminal OUT, an overcurrent detection terminal OC, and an overheat detection terminal OH, each of which outputs a gate voltage. The drain terminal of switching element 2a is connected to ground potential. Control circuit 1 and switching element 2a, including control circuit temperature detection diode 3 and switching element temperature detection diode 8, can be formed within the same resin housing or separately.

[0135] The output terminal OUT is connected to the gate terminal of the switching element 2 a , and the overcurrent detection terminal OC is connected to the source terminal of the switching element 2 a .

[0136] Within the control circuit 1, the overheat detection terminal OH is connected to a constant current source 11, the inverting input terminal of the overheat detection comparator 9, and the overcurrent reference voltage correction circuit 4. The non-inverting input terminal of the overheat detection comparator 9 is connected to the overheat reference voltage circuit 10. The overheat detection terminal OH is connected to the anode terminal of the switching element temperature detection diode 8 of the switching element 2a. The cathode terminal of the switching element temperature detection diode 8 is connected to the ground potential of the control circuit 1.

[0137] A constant current generated by a constant current source 11 constantly flows through the switching element temperature detection diode 8, and a forward voltage corresponding to the chip temperature of the switching element 2a is applied to the inverting input terminal of the overheat detection comparator 9. Assuming that the temperature characteristic of the switching element temperature detection diode 8 has a negative temperature characteristic, the overheat reference voltage circuit 10 outputs an overheat reference voltage VOH1 corresponding to the temperature TH. Consequently, when the chip temperature is below TH, the overheat detection comparator 9 outputs a low-level protection activation signal. If the chip temperature exceeds TH, the overheat detection comparator 9 outputs a high-level protection activation signal. When this high-level protection activation signal is output, the control circuit 1 simultaneously controls the switching element 2a to be turned off while outputting an alarm signal from the alarm output circuit.

[0138] Within the control circuit 1, the overcurrent detection terminal OC is connected to the sense voltage detection resistor 7 and the inverting input terminal of the overcurrent detection comparator 6. The non-inverting input terminal of the overcurrent detection comparator 6 is connected to the overcurrent reference voltage correction circuit 4. The output of the overcurrent detection comparator 6 is connected to the input of the filter 13, which removes components other than the voltage proportional to the collector current.

[0139] A constant current generated by a constant current source 12 always flows through the temperature detection diode 3 of the control circuit, and a forward voltage corresponding to the temperature of the control circuit 1 is applied as VF2 to the overcurrent reference voltage correction circuit 4 .

[0140] The overcurrent reference voltage correction circuit 4 calculates a correction value VOCa for the overcurrent reference voltage VOCo output from the overcurrent reference voltage circuit 5 based on the signal VF1 obtained from the switching element temperature detection diode 8 and the signal VF2 obtained from the temperature detection diode 3 of the above-mentioned control circuit, and sends the corrected overcurrent reference voltage VOC to the non-inverting input terminal of the overcurrent detection comparator 6.

[0141] The overcurrent detection comparator 6 compares the source voltage of the switching element 2 a with the overcurrent reference voltage VOC and sends a protection operation signal.

[0142] Figure 2The first example of the overcurrent reference voltage correction circuit 4 of the present invention is shown. It comprises two differential amplifier circuits 121 and 131. The first differential amplifier circuit 121 includes a comparator 122 and resistors 123 to 126. It has VF2 as its inverting input and VF1 as its non-inverting input, and outputs a correction value VOCa for correcting the overcurrent reference voltage VOCo. The second differential amplifier circuit 131 includes a comparator 132 and resistors 133 to 136. It has VOCa as its inverting input and the overcurrent reference voltage VOCo before correction as its non-inverting input, and outputs the corrected overcurrent reference voltage VOC.

[0143] Since the diode has a negative temperature characteristic, the lower the temperature of the switching element is, the higher VF1 and VF2 become.

[0144] The first differential amplifier circuit 121 calculates VF1-VF2 as the correction value VOCa, and the second differential amplifier circuit 131 outputs VOCo-VOCa=VOCo+VF2-VF1 as the corrected overcurrent reference voltage VOC.

[0145] The overcurrent reference voltage VOCo before correction of the control circuit has a positive temperature characteristic. As the temperature of the control circuit increases, the overcurrent reference voltage VOCo before correction increases, and as the temperature of the control circuit decreases, the overcurrent reference voltage VOCo before correction decreases.

[0146] Figure 3 FIG. 4 shows an example of the relationship between the switching element, the control circuit, and the output values ​​of VF1, VF2, and VOCa of the first example of the overcurrent reference voltage correction circuit 4, and FIG. Figure 4 Except Figure 3 In addition to the relationships shown, examples of the relationships between VOCo and VOC are also shown. It should be noted that the numerical values ​​in these figures are based on the assumption that T1 and T2 are expressed in degrees Celsius, and VF1, VF2, VOCa, VOCo, and VOC are expressed in volts. Furthermore, it is assumed that resistors 122 and 123 have equal resistances, VF1 = (150 - T1) × 10, VF2 = (150 - T2) × 10, the voltage of power supply 124 is 750V, VCC = 1500V, VF0 = 1500V, and VOCo = T1 × 8. However, this is merely an example. In this figure, when T1 = T2, the correction value VOCa = 0. However, as T1 increases relative to T2, VOCa outputs a more negative value with a larger absolute value. Subtracting VOCa from the reduced VOCo due to the low temperature T2 of the control device results in an overcurrent reference voltage VOC that depends primarily on the switching element temperature.

[0147] Figure 5A second example of the overcurrent reference voltage correction circuit 4 of the present invention is shown. The temperature detection unit is assumed to have a positive temperature characteristic, and the inputs of VF1 and VF2 are inverted relative to the first differential amplifier circuit 121 of the first example.

[0148] The first differential amplifier circuit 121 calculates VF2-VF1 as the correction value VOCa, and the second differential amplifier circuit 131 outputs VOCo-VOCa=VOCo+VF1-VF2 as the corrected overcurrent reference voltage VOC. As T1 is higher than T2, the correction value VOCa outputs a larger negative value with a larger absolute value, and the overcurrent reference voltage VOC becomes a value that basically depends only on the switching element.

[0149] Figure 6 A third example of the overcurrent reference voltage correction circuit 4 of the present invention is shown. This third example has a configuration in which a digitizing circuit 101 is inserted into the non-inverting input side of the first differential amplifier circuit 121 of the first example of the overcurrent reference voltage correction circuit 4. The digitizing circuit 101 performs multi-level digitization processing on the input value and outputs the result. Figure 6 The digitizing circuit 101 is used to perform digitization at three levels. It should be noted that the number of digitization levels is not limited to three.

[0150] The digitization circuit 101 includes: two comparators 102 and 103, which have the signal from VF1 as the inverting input and two reference potentials as the non-inverting input; two switches 104 and 105 for three potentials; three resistors 106 to 108 on the upstream side; and four resistors 109 to 112 on the downstream side. The digitization circuit 101 outputs the potential VF1a obtained from the resistors 109 to 112.

[0151] VF1 is input to the inverting input terminals of comparators 102 and 103 of digitizing circuit 101. Resistors 106, 107, and 108 are connected in series to potential VCC in this order, and the end of resistor 108 not connected to resistor 107 is grounded. The non-inverting input terminal of comparator 102 is connected between resistors 106 and 107, and the non-inverting input terminal of comparator 103 is connected between resistors 107 and 108, respectively.

[0152] The resistors 109 , 110 , 111 , and 112 are connected in series to the potential VCC in this order, and the end of the resistor 112 that is not connected to the resistor 111 is grounded.

[0153] A switch 104 is connected between resistors 110 and 111 and is turned on and off depending on the authenticity of the output signal of comparator 102. A switch 105 is connected between resistors 111 and 112 and is turned on and off depending on the authenticity of the output signal of comparator 103.

[0154] The remaining ends of the switches 104 and 105 are connected to each other between the resistor 109 and the resistor 110 , and are output as VF1 a to the first differential amplifier circuit 121 .

[0155] Comparators 102 and 103 compare VF1 with the overcurrent reference voltage generated by resistors 106 to 108 , and switch 104 and switch 105 are turned on and off according to the authenticity of comparator 102 and comparator 103 , respectively.

[0156] When the temperature of the switching element is within the standard range, VF1 becomes a high value, and both comparators 102 and 103 output false values, switches 104 and 105 are opened, and in the series connection of resistors 109 to 112, a high potential is obtained between resistor 109 and resistor 110 and is output as VF1a.

[0157] However, when the temperature of the switching element is slightly higher than the standard range, a true value is output from comparator 102 and a false value is output from 103, then switch 104 is turned on, and in the series connection of resistors 109, 111, and 112, a slightly higher potential obtained between resistor 109 and resistor 111 is output as VF1a.

[0158] Furthermore, when the temperature of the switching element is higher than the standard range, VF1 becomes a low value, and comparators 102 and 103 all output true values, then switches 104 and 105 are turned on, and in the series connection of resistors 109 and 112, the higher potential obtained between resistors 109 and 112 is output as VF1a.

[0159] The first differential amplifier circuit 121 calculates VF1a-VF2 as the correction value VOCa, and the second differential amplifier circuit 131 outputs VOCo-VOCa=VOCo+VF2-VF1a as the corrected overcurrent reference voltage VOC.

[0160] Figure 7 FIG. 4 shows an example of the relationship between the switching element, the control circuit, and the output values ​​of VF1, VF2, VF1a, and VOCa in the third example of the overcurrent reference voltage correction circuit 4. Figure 8 Except Figure 7In addition to the relationships shown, an example of the relationship between VOCo and VOC is also shown. Note that the numerical values ​​in these figures are based on the assumption that the units of T1 and T2 are Celsius, and the units of VF1, VF2, VF1a, VOCa, VOCo, and VOC are V. Furthermore, for the resistance values ​​R106 to R112 of resistors 106 to 112, it is assumed that R106 = R107 = R108, R123 = R124 = R125 = R126, R133 = R134 = R135 = R136, and the relationship R109:R110:R111:R112 = 1:4:20:5 holds. Furthermore, VF1 = (150 - T1) × 10, VF2 = (150 - T2) × 10, VCC = 1500 V, VF0 = 1500 V, and VOCo = T1 × 8. This is merely an example. In this figure, for the three levels of T1 below 50°C, above 50°C and below 100°C, and above 100°C, that is, for the three levels of VF1 exceeding 1000V, exceeding 500V and below 1000V, and below 500V, VF1a = 250W, 750W, and 1250W are output, respectively. When T1 is close to T2, the correction value VOCa of the overcurrent reference voltage VOCo approaches 0. However, as T1 increases above T2, the absolute value of VOCa becomes increasingly negative. Subtracting VOCa from VOCo, which has been reduced due to the low temperature T2 of the controlled device, results in the overcurrent reference voltage VOC becoming a value that depends primarily on the temperature of the switching element.

[0161] While the first and second methods process VF1 and VF2 as continuous analog values, the third method processes the inverting input VF1a of the first differential amplifier circuit 121 as discrete values ​​of three or more levels: standard, slightly higher, and higher. Therefore, the output overcurrent reference voltage correction value VOCa and the overcurrent reference voltage VOC also become slightly discrete values.

[0162] The digitizing circuit 101 may be connected to the inverting input side of the first differential amplifier circuit 121, or to the output side of the second differential amplifier circuit 131, or a combination of these. Similarly, when the temperature detection unit of the switching element and the control circuit has a positive temperature characteristic, the same connection can be made.

[0163] Figure 9 shows a fourth example of the overcurrent reference voltage correction circuit 4, namely, an example in which a digitizing circuit 101 is inserted on the inverting input side of the differential amplifier circuit 121. In this embodiment, the digitizing circuit 101 receives VF2 as an input value and outputs a digitized value VF2a thereof. Furthermore, the first differential amplifier circuit 121 receives VF1 on its non-inverting input side and VF2a on its inverting input side.

[0164] Figure 10 shows a fifth example of the overcurrent reference voltage correction circuit 4, namely, an example in which a digitizing circuit 101 is inserted on the output side of the differential amplifier circuit 131. In the fifth example, the digitizing circuit 101 uses the output value VOCb of the second differential amplifier circuit 131 as an input value and outputs the digitized value as VOC.

[0165] In the case where the temperature of the control circuit is extremely higher than the temperature of the switching element, that is, in the previous technology, the overcurrent protection value becomes higher than the originally required value, so that protection is not performed within the current range that needs protection, resulting in the so-called insufficient range of overcurrent protection, these overcurrent reference voltage correction circuits 4 can also narrow the above-mentioned insufficient range.

[0166] Figure 11 and Figure 12 The figure shows the relationship between the temperature T1, T2 and VOCa and VOC in the first example of the overcurrent reference voltage correction circuit 4 when the temperature detection unit of the switching element and the control circuit has a negative temperature characteristic. Figure 3 and Figure 4 The range of expression is expanded to include the relationship of T2 > T1, and the definitions of each value are the same as those of the first embodiment of the circuit described above. As shown in this figure, when the control circuit temperature is higher than the switching element temperature, the VOC output by the circuit described above also becomes a value that depends largely solely on the switching element temperature.

[0167] Figure 17 1 shows the operating region of the overcurrent protection of the power semiconductor device of the first example of the overcurrent reference voltage correction circuit 4 of the present invention. The maximum operating temperature set in the power semiconductor device is TH, and the minimum operating temperature is TL.

[0168] For example, when the temperature of the switching element is TH and the temperature of the control circuit is TL, the intersection 203 of the sense voltage 202 and the overcurrent reference voltage VBH, ie, the collector current ICTH, becomes the overcurrent value, and the margin becomes narrow as shown by 208 .

Claims

1. A semiconductor device, characterized in that: have: Switching elements; a control circuit that controls the switching element and includes an overcurrent detection circuit for the switching element; a first temperature detection unit, configured to detect the temperature of the switching element; as well as A second temperature detection unit is used to detect the temperature of the control circuit. The control circuit includes a reference correction circuit that corrects an overcurrent reference value of the overcurrent detection circuit based on a first detection value detected by the first temperature detection unit and a second detection value detected by the second temperature detection unit, and outputs the corrected overcurrent reference value. The reference correction circuit includes: a first differential amplifier circuit to which the first detection value and the second detection value are input; and a second differential amplifier circuit to which the output value of the first differential amplifier circuit and the overcurrent reference value of the overcurrent detection circuit are input.

2. The semiconductor device according to claim 1, wherein The reference correction circuit corrects the overcurrent reference value based on the first detection value when determining based on the first detection value and the second detection value that the difference between the temperature of the switching element and the temperature of the control circuit is equal to or greater than a predetermined value.

3. The semiconductor device according to claim 1, wherein The switching element is mounted on a first circuit substrate formed of an insulating substrate having a predetermined circuit pattern and on which electronic components are mounted.

4. The semiconductor device according to claim 2, wherein The switching element is mounted on a first circuit substrate formed of an insulating substrate having a predetermined circuit pattern and on which electronic components are mounted.

5. The semiconductor device according to claim 1, wherein The control circuit is mounted on a second circuit substrate formed of an insulating substrate having a predetermined circuit pattern and on which electronic components are mounted.

6. The semiconductor device according to claim 2, wherein The control circuit is mounted on a second circuit substrate formed of an insulating substrate having a predetermined circuit pattern and on which electronic components are mounted.

7. The semiconductor device according to claim 3, wherein The control circuit is mounted on a second circuit substrate formed of an insulating substrate having a predetermined circuit pattern and on which electronic components are mounted.

8. The semiconductor device according to claim 4, wherein The control circuit is mounted on a second circuit substrate formed of an insulating substrate having a predetermined circuit pattern and on which electronic components are mounted.

9. The semiconductor device according to claim 1, wherein The switching element and the control circuit are mounted on the same third circuit substrate. The third circuit substrate is formed of an insulating substrate having a predetermined circuit pattern and on which electronic components are mounted.

10. The semiconductor device according to claim 2, wherein The switching element and the control circuit are mounted on the same third circuit substrate. The third circuit substrate is formed of an insulating substrate having a predetermined circuit pattern and on which electronic components are mounted.

11. The semiconductor device according to any one of claims 1 to 10, wherein: A first resin case is molded so as to cover the switch element.

12. The semiconductor device according to any one of claims 1 to 10, wherein: A second resin case is molded so as to cover the control circuit.

13. The semiconductor device according to any one of claims 1 to 10, wherein: The same third resin case is molded so as to cover the switching element and the control circuit.

14. The semiconductor device according to any one of claims 1 to 10, wherein: The first temperature detection unit provided for the switching element is provided in the same element as the switching element.

15. The semiconductor device according to claim 3 or 4, wherein: The first temperature detection unit provided for the switching element is provided at a position on the first circuit substrate where the temperature of the switching element can be measured.

16. The semiconductor device according to claim 9 or 10, wherein: The first temperature detection unit provided for the switching element is provided at a position on the third circuit substrate where the temperature of the switching element can be measured.

17. The semiconductor device according to claim 11, wherein The first temperature detection unit provided for the switching element is provided in or near the first resin case at a position capable of measuring the temperature of the switching element.

18. The semiconductor device according to claim 13, wherein The first temperature detection unit provided for the switching element is provided in or near the third resin case at a position capable of measuring the temperature of the switching element.

19. The semiconductor device according to any one of claims 1 to 10, wherein The second temperature detection unit provided for the control circuit is provided in the same element as the control circuit.

20. The semiconductor device according to any one of claims 5 to 8, wherein The second temperature detection unit provided for the control circuit is provided at a position on the second circuit substrate where the temperature of the control circuit can be measured.

21. The semiconductor device according to claim 9 or 10, wherein: The second temperature detection unit provided for the control circuit is provided at a position on the third circuit substrate capable of measuring the temperature of the control circuit.

22. The semiconductor device according to claim 12, wherein The second temperature detection unit provided for the control circuit is provided in a position inside or near the second resin case at which the temperature of the control circuit can be measured.

23. The semiconductor device according to claim 13, wherein The second temperature detection unit provided for the control circuit is provided at a position capable of measuring the temperature of the control circuit within or near the third resin case.

24. The semiconductor device according to any one of claims 1 to 10, wherein As the switching element, an IGBT is used.

25. The semiconductor device according to any one of claims 1 to 10, wherein As the switching element, MOSFET is used.

26. The semiconductor device according to any one of claims 1 to 10, wherein The first temperature detection unit and the second temperature detection unit have negative temperature characteristics.

27. The semiconductor device according to any one of claims 1 to 10, wherein The first temperature detection unit and the second temperature detection unit have positive temperature characteristics.

28. The semiconductor device according to any one of claims 1 to 10, wherein The reference correction circuit includes a digitizing circuit that digitizes an input value into multiple levels according to a magnitude relationship of the input values ​​and outputs the digitized value.

29. The semiconductor device according to claim 28, wherein The reference correction circuit is connected to the output side of the digitization circuit at the input side of the first detection value.

30. The semiconductor device according to claim 28, wherein The reference correction circuit is connected to the output side of the digitization circuit at the input side of the second detection value.

31. The semiconductor device according to claim 29, wherein The reference correction circuit is connected to the output side of the digitization circuit at the input side of the second detection value.

32. The semiconductor device according to claim 28, wherein The reference correction circuit is connected to the input side of the digitization circuit at the output side of the reference correction circuit.

33. The semiconductor device according to claim 29, wherein The reference correction circuit is connected to the input side of the digitization circuit at the output side of the reference correction circuit.

34. The semiconductor device according to claim 30, wherein The reference correction circuit is connected to the input side of the digitization circuit at the output side of the reference correction circuit.

35. The semiconductor device according to claim 31, wherein The reference correction circuit is connected to the input side of the digitization circuit at the output side of the reference correction circuit.

36. The semiconductor device according to any one of claims 1 to 10, wherein The overcurrent detection circuit has a function of receiving and comparing a current detection value based on the current flowing through the switching element and the corrected overcurrent reference value as inputs, and a function of outputting a signal based on a result of the comparison.

37. A method for overcurrent protection of a semiconductor device, characterized in that: include: detecting a first detection value using a first temperature detection unit for detecting the temperature of the switching element; detecting a second detection value using a second temperature detection unit for temperature detection of a control circuit that controls the switching element and includes an overcurrent detection circuit for the switching element; as well as The reference correction circuit included in the control circuit corrects the overcurrent reference value of the overcurrent detection circuit based on the first detection value and the second detection value, and outputs the corrected overcurrent reference value. The reference correction circuit includes: a first differential amplifier circuit to which the first detection value and the second detection value are input; and a second differential amplifier circuit to which the output value of the first differential amplifier circuit and the overcurrent reference value of the overcurrent detection circuit are input.

38. The overcurrent protection method for a semiconductor device according to claim 37, wherein: The first temperature detection unit and the second temperature detection unit have negative temperature characteristics, The reference correction circuit calculates an overcurrent reference correction value by subtracting the second detection value from the first detection value, and further calculates the corrected overcurrent reference value by subtracting the overcurrent reference correction value from the original overcurrent reference value.

39. The overcurrent protection method for a semiconductor device according to claim 37, wherein: The first temperature detection unit and the second temperature detection unit have positive temperature characteristics, The reference correction circuit calculates an overcurrent reference correction value by subtracting the first detection value from the second detection value, and further calculates the corrected overcurrent reference value by subtracting the overcurrent reference correction value from the original overcurrent reference value.

40. The overcurrent protection method for a semiconductor device according to any one of claims 37 to 39, wherein: The reference correction circuit has a digitization circuit that digitizes and outputs the input value at multiple levels according to the size relationship of the input value, and digitizes and processes the first detection value, the second detection value, and one or multiple values ​​of the corrected overcurrent reference value.

41. The overcurrent protection method for a semiconductor device according to any one of claims 37 to 39, wherein: A current detection value based on the current flowing through the switching element is compared with the overcurrent reference value, and generation of an overcurrent is detected when the current detection value exceeds the overcurrent reference value.

42. The overcurrent protection method for a semiconductor device according to claim 40, wherein: A current detection value based on the current flowing through the switching element is compared with the overcurrent reference value, and generation of an overcurrent is detected when the current detection value exceeds the overcurrent reference value.

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