Voltage-controlled semiconductor device driver

Abstract

The present invention monitors, with high accuracy, the temperature of a semiconductor chip of a voltage-controlled semiconductor element.　A drive signal SDRV output by a drive circuit (24) is delayed in a delay circuit (28) so that a leading front edge of a delay signal delayed in the delay circuit (28) reaches a mirror effect period while an IGBT (10) is turned on, and a one-shot circuit (30) receives the delay signal and outputs a pulse signal having a pulse width that is shorter than the mirror effect period. A comparator (36) compares a gate voltage VGE with a reference voltage Vref corresponding to an overheat detection threshold voltage, and outputs an overheat detection signal if the gate voltage VGE reaches or exceeds the overheat detection threshold voltage. By monitoring the gate voltage VGE which is temperature-dependent on the chip temperature of the IGBT (10), the chip temperature of the IGBT (10) is directly monitored.

Description

[Technical field]

[0001] The present invention , electric The present invention relates to a driving device for a pressure-controlled semiconductor element. [Background technology]

[0002] There are semiconductor devices that perform switching control of inductive loads and perform power conversion. Some of these semiconductor devices include a semiconductor switching element and a drive device that drives the semiconductor switching element. The semiconductor switching element is a voltage-controlled semiconductor element such as an IGBT (Insulated Gate Bipolar Transistor) or a MOSFET (Metal-Oxide-Semiconductor Field-Effect Transistor).

[0003] For voltage-controlled semiconductor elements, the allowable temperature is defined by the absolute maximum rating. If a voltage-controlled semiconductor element is operated above the maximum allowable temperature, the semiconductor chip may be thermally destroyed. To prevent or prevent this thermal destruction of the semiconductor chip, the chip temperature is monitored, and if it is assumed that the chip temperature is too high, the voltage-controlled semiconductor element is operated below the rated value or stopped.

[0004] As a method for detecting the chip temperature of a voltage-controlled semiconductor element, a thermistor is provided in the semiconductor device to detect the temperature inside the case and predict the chip temperature from the operating conditions. Another method is to form a temperature detection diode integrally on the chip of the voltage-controlled semiconductor element and directly measure the chip temperature from the temperature characteristics of the temperature detection diode.

[0005] The method of predicting chip temperature using a thermistor has the characteristic that it cannot follow a sudden rise in temperature caused by an overcurrent due to a load fluctuation because the thermistor is mounted at a position away from the semiconductor chip. On the other hand, the method of measuring chip temperature using a temperature detection diode reduces the active area because the temperature detection diode is built on the semiconductor chip, and further reduces the active area because a diode-only electrode is provided on the semiconductor chip. For this reason, when a temperature detection diode is mounted on the chip of a semiconductor switching element with a small current rating, the chip size becomes large.

[0006] In view of this, a method has been proposed for detecting the temperature of a chip of a voltage-controlled semiconductor element without using a thermistor or a temperature detection diode (see, for example, Patent Documents 1 and 2).

[0007] According to the technology described in Patent Document 1, the duration of the Miller plateau is detected when the IGBT is turned off, and the temperature is detected by converting the duration of the Miller plateau into a temperature. That is, the technology in Patent Document 1 determines the IGBT junction temperature from the time delay of the Miller plateau by utilizing the fact that the time delay of the Miller plateau is interdependent with the junction temperature of the IGBT.

[0008] The technology in Patent Document 2 measures the change in gate voltage over time during switching operation of a semiconductor device, and by utilizing the fact that the change in gate voltage over time is temperature-dependent on the temperature of the semiconductor device, the temperature of the semiconductor device is estimated from the measured change in gate voltage over time. [Prior art documents] [Patent documents]

[0009] [Patent Document 1] JP 2013-142704 A [Patent Document 2] JP 2020-072569 A Summary of the Invention [Problem to be solved by the invention]

[0010] However, the technology of Patent Document 1 has a problem that it is difficult to accurately detect the Miller effect period, which is the time delay of the Miller plateau.In addition, the technology of Patent Document 2 has a configuration in which the gate voltage rise time is measured and the temperature of the semiconductor device corresponding to the gate voltage rise time is calculated by a microcomputer by referring to the temperature dependency information, so there is a problem that the driving device becomes large.

[0011] The present invention has been made in view of the above points, and provides a voltage-controlled semiconductor device that can monitor the temperature of a semiconductor chip with high accuracy and does not require an increased size of a configuration for detecting the temperature of the semiconductor chip. Drive The object of the present invention is to provide a moving device. [Means for solving the problem]

[0013] In order to solve the above problems, the present invention provides A drive device for a voltage-controlled semiconductor element is provided, the drive device for driving the voltage-controlled semiconductor element comprising: a drive circuit for driving the gate of the voltage-controlled semiconductor element, a gate resistor installed between the drive circuit and the gate of the voltage-controlled semiconductor element, a delay circuit for delaying a drive signal output by the drive circuit by a predetermined time until the drive signal reaches a Miller effect period occurring during a period in which the gate voltage changes transiently, a one-shot circuit for outputting a pulse signal having a pulse width shorter than the Miller effect period from the leading edge of a rising edge or trailing edge of a falling edge of the delayed signal output by the delay circuit, a comparator for comparing a gate voltage that is temperature-dependent as a chip temperature of the voltage-controlled semiconductor element with a reference voltage equivalent to an overheat detection threshold voltage, and an AND circuit that receives the pulse signal output by the one-shot circuit and the output signal of the comparator, and outputs an overheat detection signal when the gate voltage exceeds the reference voltage. Effect of the Invention

[0016] The temperature detection method and drive device for a voltage-controlled semiconductor element configured as described above can monitor the chip temperature of a voltage-controlled semiconductor element directly and in real time, thereby enabling the chip temperature to be monitored with high accuracy and enabling the configuration for detecting the chip temperature to be realized with a small-scale circuit configuration. The above and other objects, features and advantages of the present invention will become apparent from the following description taken in conjunction with the accompanying drawings illustrating preferred embodiments of the present invention. [Brief description of the drawings]

[0017] [Figure 1] 1 is a circuit diagram showing a configuration example of an IGBT driving device according to a first embodiment. [Diagram 2] FIG. 13 is a diagram showing the relationship between the gate voltage and the chip temperature during the Miller effect period. [Diagram 3] 4 is a time chart illustrating the operation of the IGBT driving device according to the first embodiment. [Figure 4] FIG. 11 is a circuit diagram showing a configuration example of an IGBT driving device according to a second embodiment. [Diagram 5] FIG. 11 is a circuit diagram showing a configuration example of an IGBT driving device according to a third embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0018] Hereinafter, the embodiment of the present invention will be described in detail with reference to the drawings, taking as an example a case where an IGBT is used as a voltage-controlled semiconductor element and the invention is applied to a drive device for driving the IGBT. In the drawings, parts denoted by the same reference numerals indicate the same components.

[0019] FIG. 1 is a circuit diagram showing an example of the configuration of an IGBT drive device according to a first embodiment, FIG. 2 is a diagram showing the relationship between the gate voltage and the chip temperature during the Miller effect period, and FIG. 3 is a time chart explaining the operation of the IGBT drive device according to the first embodiment.

[0020] 1 shows an IGBT 10 which is a semiconductor switching element, and a drive device 20 which drives the IGBT 10. The IGBT 10 and the drive device 20 are built into, for example, a single package to constitute a semiconductor device called an intelligent power module.

[0021] The IGBT 10 is connected in inverse parallel to a free wheeling diode (FWD) 12 that returns the energy stored in the inductive load to the power supply when the IGBT 10 is turned off. That is, the anode of the FWD 12 is connected to the emitter of the IGBT 10, and the cathode of the FWD 12 is connected to the collector of the IGBT 10.

[0022] The driving device 20 includes a pre-driver 22, a drive circuit 24, and a gate resistor 26. The pre-driver 22 has a terminal IN to which a PWM (Pulse Width Modulation) signal is input from an external higher-level device, and an output terminal of the pre-driver 22 is connected to an input terminal of the drive circuit 24. An output terminal of the drive circuit 24 is connected to one terminal of the gate resistor 26, and the other terminal of the gate resistor 26 is connected to a terminal G connected to the gate of the IGBT 10. The drive circuit 24 is also connected to a terminal E connected to the emitter of the IGBT 10. The PWM signal input to the terminal IN is converted into a drive signal SDRV via the pre-driver 22 and the drive circuit 24, and the drive signal SDRV becomes a gate voltage VGE via the gate resistor 26 and is supplied to the terminal G.

[0023] The drive device 20 also includes a delay circuit 28, a one-shot circuit 30, resistors 32 and 34, a comparator 36, and an AND circuit 38. The input terminal of the delay circuit 28 is connected to a connection between the output terminal of the drive circuit 24 and one terminal of the gate resistor 26, and the output terminal of the delay circuit 28 is connected to an input terminal of the one-shot circuit 30. One terminal of the resistor 32 is connected to a power supply line, the other terminal of the resistor 32 is connected to one terminal of the resistor 34, and the other terminal of the resistor 34 is connected to ground. The resistors 32 and 34 form a voltage divider circuit and output a reference voltage Vref. The reference voltage Vref corresponds to an overheat detection threshold voltage, and is, for example, a voltage corresponding to 175° C., which is the upper limit of the guaranteed operating temperature of the IGBT 10.

[0024] The comparator 36 has a non-inverting input terminal connected to the connection between the other terminal of the gate resistor 26 and the terminal G, and an inverting input terminal connected to the connection between the other terminal of the resistor 32 and one terminal of the resistor 34. The output terminal of the one-shot circuit 30 is connected to a first input terminal of an AND circuit 38, and the output terminal of the comparator 36 is connected to a second input terminal of the AND circuit 38. The output terminal of the AND circuit 38 is connected to an alarm output terminal ALM that notifies an external host device of an overheating detection signal.

[0025] Here, the gate voltage VGE of the IGBT 10 during the Miller effect period at turn-on has temperature dependency on the chip temperature Tvj of the IGBT 10. As shown in Fig. 2, the temperature dependency is such that the gate voltage VGE changes linearly with respect to the chip temperature Tvj, and therefore the chip temperature Tvj can be detected from the gate voltage VGE.

[0026] Next, the operation of the drive device 20 having the above configuration will be described with reference to the time chart of Fig. 3. In the time chart of Fig. 3, from the top, the drive signals SDRV, Gate resistor 26 and Terminals G and 4 shows the gate voltage VGE during this period, the delay signal output by the delay circuit 28, the pulse signal output by the one-shot circuit 30, and the overheat detection signal at the alarm output terminal ALM.

[0027] When a PWM signal is input to the terminal IN of the drive device 20, the PWM signal is input to the drive circuit 24 via the pre-driver 22 and output as a drive signal SDRV from the drive circuit 24. When this drive signal SDRV is applied to the gate of the IGBT 10 via the gate resistor 26, the gate voltage VGE changes as shown in FIG.

[0028] When the drive signal SDRV rises from low (L) level to high (H) level, the H-level voltage charges the gate-emitter capacitance of the IGBT 10 via the gate resistor 26. When the charging voltage of the gate-emitter capacitance exceeds the on-threshold voltage of the IGBT 10, the IGBT 10 turns on, and the collector-emitter of the IGBT 10 is almost short-circuited. As a result, the gate-emitter capacitance and the gate-collector capacitance (Miller capacitance) are connected to the gate of the IGBT 10, and the IGBT 10 operates as a Miller integrator. During the Miller effect period Tm, which is the operation period, the gate voltage VGE remains constant. When the Miller effect period Tm ends, further charging continues to the gate of the IGBT 10, so the gate voltage VGE rises until it reaches the H level of the drive signal SDRV.

[0029] After the drive signal SDRV becomes L level, the gate voltage VGE follows a change inverse to that when the IGBT 10 is turned on, and drops until it reaches the L level potential of the drive signal SDRV.

[0030] The drive signal SDRV is also input to a delay circuit 28. The delay circuit 28 outputs a delayed signal that is delayed from the drive signal SDRV by a delay time Td. This delay time Td is the time from the leading edge of the rising edge of the drive signal SDRV to an arbitrary point in time during the Miller effect period Tm of the gate voltage VGE, and is determined based on the switching characteristics of the IGBT 10. The delayed signal is input to a one-shot circuit 30, which outputs a pulse signal having a certain width from the leading edge of the rising edge of the delayed signal. The pulse signal output by the one-shot circuit 30 has a pulse width shorter than the Miller effect period Tm, and serves as a signal for acquiring the gate voltage VGE during the Miller effect period Tm.

[0031] The gate voltage VGE is also supplied to a non-inverting input terminal of a comparator 36. The comparator 36 receives a reference voltage Vref corresponding to the overheat detection threshold voltage at its inverting input terminal, and constitutes a binary circuit that determines whether the gate voltage VGE reaches the overheat detection threshold voltage. The comparator 36 outputs an L level signal when the gate voltage VGE is less than the reference voltage Vref corresponding to the overheat detection threshold voltage, and outputs an H level signal when the gate voltage VGE is equal to or greater than the reference voltage Vref.

[0032] The AND circuit 38 receives the pulse signal output by the one-shot circuit 30 at a first input terminal, and receives the output signal of the comparator 36 at a second input terminal. As a result, the AND circuit 38 allows the output signal of the comparator 36 to pass only during the period in which the AND circuit 38 receives the pulse signal.

[0033] When the chip temperature of the IGBT 10 is at room temperature within the range of guaranteed operating temperatures, the gate voltage VGE during the Miller effect period Tm is less than the reference voltage Vref, so the comparator 36 outputs an L-level signal, and therefore the AND circuit 38 outputs an L-level signal.

[0034] When the chip temperature of the IGBT 10 is high and exceeds the range of guaranteed operating temperatures, the gate voltage VGE during the Miller effect period Tm becomes equal to or higher than the reference voltage Vref, so that the comparator 36 outputs an H-level signal, and the AND circuit 38 outputs an H-level signal. This H-level signal is notified to an external host device from the alarm output terminal ALM as an overheat detection signal.

[0035] In this embodiment, the overheat detection signal is output from the alarm output terminal ALM to the outside, but it may be input to an overheat detection and protection circuit (not shown) to forcibly turn off the IGBT 10.

[0036] FIG. 4 is a circuit diagram showing a configuration example of an IGBT driving device according to the second embodiment. The drive device 20a for IGBT 10 in the second embodiment is configured to detect and output the chip temperature in real time, whereas the drive device 20 in the first embodiment detects overheating of the IGBT 10 and outputs an alarm.

[0037] The driving device 20a includes a pre-driver 22, a drive circuit 24, a gate resistor 26, a delay circuit 28, and a one-shot circuit 30, which are the same as those included in the driving device 20 of the first embodiment, and therefore will not be described in detail here.

[0038] The driving device 20a also includes a sample-and-hold circuit 40. The sample-and-hold circuit 40 includes an operational amplifier 42, a switch element 44, a capacitor 46, and an operational amplifier 48. The operational amplifier 42 has an inverting input terminal connected to its own output terminal to form a voltage follower circuit, and a non-inverting input terminal connected to a terminal G connected to the gate of the IGBT 10. The output terminal of the operational amplifier 42 is connected to one terminal of the switch element 44, and the other terminal of the switch element 44 is connected to one terminal of the capacitor 46 and a non-inverting input terminal of the operational amplifier 48. The other terminal of the capacitor 46 is connected to ground. The control terminal of the switch element 44 is connected to the output terminal of the one-shot circuit 30. The operational amplifier 48 has an inverting input terminal connected to its own output terminal to form a voltage follower circuit. The output terminal of the operational amplifier 48 is connected to the chip temperature output terminal TMP.

[0039] According to the sample-and-hold circuit 40 of the driving device 20a, the gate voltage VGE is received by the operational amplifier 42 having a high input impedance, thereby minimizing the influence of connecting the sample-and-hold circuit 40 to the terminal G. The operational amplifier 42 constitutes a voltage follower circuit, and outputs the gate voltage VGE input to the non-inverting input terminal as is. When the switch element 44 receives an H-level pulse signal output by the one-shot circuit 30 at its control terminal, it turns on (conducts) only during the period during which the pulse signal is received, and applies the voltage output by the operational amplifier 42 (≈gate voltage VGE) to the capacitor 46. At this time, the terminal voltage of the capacitor 46 becomes a voltage that follows the voltage output by the operational amplifier 42.

[0040] When the pulse signal output by the one-shot circuit 30 becomes an L level, the switch element 44 turns off (non-conductive), and the terminal voltage of the capacitor 46 is held at the voltage when the switch element 44 turned off. The voltage held in the capacitor 46 is output as it is as a chip temperature detection signal by an operational amplifier 48 that constitutes a voltage follower circuit, and is notified to an external higher-level device from a chip temperature output terminal TMP.

[0041] When the external higher-level device receives the chip temperature detection signal from the drive device 20a, it obtains the chip temperature from the chip temperature detection signal. That is, the higher-level device has data indicating the relationship between the gate voltage VGE and the chip temperature Tvj during the Miller effect period shown in Fig. 2, and converts the gate voltage VGE indicated by the chip temperature detection signal into the corresponding chip temperature Tvj.

[0042] As a result, this driving device 20a can monitor the chip temperature of the IGBT 10 directly and in real time, thereby enabling the chip temperature to be monitored with high accuracy, and the configuration for detecting the chip temperature can be realized with a small-scale circuit configuration.

[0043] FIG. 5 is a circuit diagram showing a configuration example of an IGBT driving device according to the third embodiment. The driving device 20b of the IGBT 10 in the third embodiment has the overheating detection function of the IGBT 10 that the driving device 20 in the first embodiment has, and the chip temperature detection function of the IGBT 10 that the driving device 20a in the second embodiment has.

[0044] The driving device 20b includes a pre-driver 22, a drive circuit 24, a gate resistor 26, a delay circuit 28, a one-shot circuit 30, resistors 32 and 34, a comparator 36, an AND circuit 38, and a sample-and-hold circuit 40. The above components of the driving device 20b are the same as those of the driving device 20 of the first embodiment and the driving device 20a of the second embodiment. However, the gate voltage VGE input to the non-inverting input terminal of the comparator 36 is obtained from the output terminal of the operational amplifier 42 of the sample-and-hold circuit 40.

[0045] As described above, the drive unit 20b is the same as the drive unit 20 of the first embodiment and the drive unit 20a of the second embodiment, and its operation is also the same as that of the drive units 20 and 20a, so a detailed description will be omitted here. The drive unit 20b can realize both overheat detection and temperature detection.

[0046] In the above embodiment, the gate voltage VGE during the Miller effect period when the IGBT 10 is turned on is detected, and the chip temperature corresponding to the gate voltage VGE is obtained. However, the gate voltage VGE during the Miller effect period when the IGBT 10 is turned off or during both Miller effect periods when the IGBT 10 is turned on and off may be detected to obtain the chip temperature. In this case, the delay circuit 28 outputs a delayed signal delayed by the time from the trailing edge of the falling edge of the drive signal SDRV to an arbitrary time during the Miller effect period Tm of the gate voltage VGE. The drive devices 20 and 20a may be devices that drive MOSFETs instead of the IGBT 10. While one aspect of the temperature detection method and driving device for a voltage-controlled semiconductor device of the present invention has been described above based on the embodiment, this is merely an example and the present invention is not limited to the above description. The foregoing merely illustrates the principles of the present invention. Further, since numerous modifications and changes are possible to those skilled in the art, the present invention is not limited to the exact construction and application shown and described above, and all corresponding modifications and equivalents are deemed to be within the scope of the present invention according to the appended claims and their equivalents. [Explanation of symbols]

[0047] 10 IGBT 12 FWD 20, 20a, 20b Drive unit 22 Pre-driver 24 Drive circuit 26 Gate resistor 28 Delay Circuit 30 One-shot circuit 32,34 Resistance 36 Comparator 38 AND Circuit 40 Sample and hold circuit 42 Operational Amplifiers 44 Switching element 46 Capacitor 48 Operational Amplifiers

Claims

1. A drive device for driving a voltage-controlled semiconductor element, comprising: a drive circuit for driving a gate of the voltage controlled semiconductor element; a gate resistor disposed between the drive circuit and the gate of the voltage-controlled semiconductor device; a delay circuit that delays the drive signal output by the drive circuit for a predetermined time until the drive signal reaches a Miller effect period that occurs during a period in which the gate voltage changes transiently; a one-shot circuit that outputs a pulse signal having a pulse width shorter than the Miller effect period from a leading edge of a rising edge or a trailing edge of a falling edge of the delayed signal output by the delay circuit; a comparator for comparing the gate voltage, which is temperature-dependent and corresponds to a chip temperature of the voltage-controlled semiconductor device, with a reference voltage corresponding to an overheat detection threshold voltage; an AND circuit that receives the pulse signal output by the one-shot circuit and an output signal of the comparator, and outputs an overheat detection signal when the gate voltage exceeds the reference voltage; A driving device for a voltage-controlled semiconductor element comprising:

2. 2. The drive device for a voltage controlled semiconductor device according to claim 1, further comprising an alarm output terminal for notifying an external device of the overheat detection signal output by said AND circuit.

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