Driving circuit for semiconductor switching element

Abstract

The drive circuit (101) is connected to the control terminal of the semiconductor switch element (1). The drive circuit (101) comprises: an input circuit (3) connected to the input terminal (50); and an output control circuit (4) connected to the input circuit (3). The pulse signal output by the output control circuit (4) is input to the dead time adjustment circuit (13). The dead time adjustment circuit (13) comprises a delay circuit. The delay circuit is capable of delaying the rising edge and falling edge of the pulse signal output by the output control circuit (4) based on the signal from the temperature analog output circuit (11, 12). The output of the dead time adjustment circuit (13) is input to the drive circuit (5). The drive circuit (5) outputs the drive signal to the output terminal (51) of the drive circuit (101).

Description

[0001] The present application is a divisional application of an application with a filing date of November 14, 2013 and an application number of 201810574156.9 (driving circuit for semiconductor switching element), and the contents thereof are cited below. Technical Field

[0002] The invention relates to a driving circuit of a semiconductor switch element. Background Art

[0003] Currently, various technologies have been proposed to protect switching elements from overheating, such as limiting current supply control based on the temperature detected by a temperature sensor. For example, as disclosed in Japanese Patent Application Laid-Open No. 2009-136061, a drive circuit that performs overheat protection based on temperature information of a semiconductor switching element is known.

[0004] Patent Document 1: Japanese Patent Application Publication No. 2009-136061

[0005] Patent Document 2: Japanese Patent Application Publication No. 2008-277433

[0006] Patent Document 3: Japanese Patent Application Publication No. 2012-253202 Summary of the invention

[0007] In a typical conventional semiconductor device, an overheat protection circuit is provided in the drive circuit for overheat protection of the semiconductor switch element. Specifically, a temperature sensor for detecting temperature is provided in the semiconductor switch element. The overheat protection circuit compares the element temperature of the semiconductor switch element with a threshold value based on the output of the temperature sensor, and stops the operation of the drive circuit when the element temperature is too high. The operation of the overheat protection circuit is to stop the drive circuit in a two-choice manner depending on whether the element temperature reaches the threshold value.

[0008] Semiconductor switch elements have temperature characteristics, for example, input capacitance changes in accordance with the element temperature. In addition, even in a drive circuit that drives a semiconductor switch element, if the temperature inside the drive circuit changes, it will also affect the circuit operation. With regard to the temperature information that affects the circuit operation of the drive circuit, it is preferred that the temperature information be more finely reflected in the operation of the drive circuit.

[0009] In addition, as described above, the overheat protection technology for detecting the temperature of a semiconductor switch element is well known. Generally, the temperature of a semiconductor device during use varies due to differences in the amount of heat generated by a semiconductor switch element and its drive circuit and the cooling structure of the semiconductor device. The inventors of the present application have discovered a technology that can perform more precise abnormality detection of a semiconductor device by utilizing this temperature difference.

[0010] The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide a driving circuit for a semiconductor switching element capable of reflecting temperature information in the operation of the driving circuit with high accuracy.

[0011] A semiconductor switch element drive circuit according to a first invention includes:

[0012] an input terminal to which an input signal is input;

[0013] an output terminal connected to a control terminal of the semiconductor switching element;

[0014] a signal circuit section that supplies a drive signal to the output terminal, the drive signal having an on edge that turns on in response to a rising edge of the input signal and an off edge that turns off in response to a falling edge of the input signal; and

[0015] a temperature detection unit including at least one of a first temperature detection unit and a second temperature detection unit, the first temperature detection unit outputting a first temperature detection signal having a correlation with the temperature of the signal circuit unit, and the second temperature detection unit receiving a second temperature detection signal from an element temperature sensor element detecting the temperature of the semiconductor switch element,

[0016] In order to reduce the difference between the delay time between the rising edge and the connection edge, i.e., the connection transmission delay time, and the delay time between the falling edge and the disconnection edge, i.e., the disconnection transmission delay time, at least one signal edge among the connection edge and the disconnection edge is delayed based on at least one of the first temperature detection signal and the second temperature detection signal.

[0017] A semiconductor switch element drive circuit according to a second invention includes:

[0018] an input terminal to which an input signal is input;

[0019] an output terminal connected to a control terminal of the semiconductor switching element;

[0020] a signal circuit unit that generates a drive signal based on the input signal and supplies the drive signal to the output terminal; and

[0021] a temperature detection unit including at least one of a first temperature detection unit and a second temperature detection unit, the first temperature detection unit outputting a first temperature detection signal having a correlation with the temperature of the signal circuit unit, and the second temperature detection unit receiving a second temperature detection signal from an element temperature sensor element detecting the temperature of the semiconductor switch element,

[0022] The signal circuit unit includes a drive circuit that supplies current to a control terminal of the semiconductor switch element.

[0023] The drive circuit of the signal circuit unit switches a drive current capability based on at least one of the first temperature detection signal and the second temperature detection signal.

[0024] A semiconductor switch element drive circuit according to a third invention includes:

[0025] an input terminal to which an input signal is input;

[0026] an output terminal connected to a control terminal of the semiconductor switching element;

[0027] a signal circuit unit that generates a driving signal according to the input signal and supplies the driving signal to the output terminal;

[0028] a temperature detection unit including at least one of a first temperature detection unit that outputs a first temperature detection signal having a correlation with the temperature of the signal circuit unit and a second temperature detection unit that receives a second temperature detection signal from an element temperature sensor element that detects the temperature of the semiconductor switch element;

[0029] Short circuit protection terminals; and

[0030] The short-circuit protection circuit transmits a stop signal to the signal circuit unit if the voltage input to the short-circuit protection terminal reaches a threshold value, and the short-circuit protection circuit sets the threshold value based on at least one of the first temperature detection signal and the second temperature detection signal.

[0031] A semiconductor switch element drive circuit according to a fourth invention includes:

[0032] an input terminal to which an input signal is input;

[0033] an output terminal connected to a control terminal of the semiconductor switching element;

[0034] a signal circuit unit that generates a driving signal according to the input signal and supplies the driving signal to the output terminal;

[0035] a temperature detection circuit which outputs a first temperature detection signal having a correlation with the temperature of the signal circuit portion;

[0036] a temperature detection terminal that receives a second temperature detection signal from a temperature sensor element of the semiconductor switch element; and

[0037] The error signal generating circuit outputs an error signal based on a difference between a temperature indicated by the first temperature detection signal and a temperature indicated by the second temperature detection signal.

[0038] Effects of the Invention

[0039] According to the present invention, since various operations of the drive circuit are adjusted using one or both of the first temperature detection signal and the second temperature detection signal, temperature information can be reflected in the operation of the drive circuit with high accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 This is a circuit block diagram showing a driving circuit for a semiconductor switch element according to Embodiment 1 of the present invention.

[0041] Figure 2 This is a circuit block diagram showing a driving circuit for a semiconductor switching element according to a second embodiment of the present invention.

[0042] Figure 3 This is a circuit block diagram showing a driving circuit for a semiconductor switch element according to a third embodiment of the present invention.

[0043] Figure 4 This is a circuit block diagram showing a driving circuit for a semiconductor switch element according to a fourth embodiment of the present invention.

[0044] Figure 5 This is a circuit block diagram showing a driving circuit for a semiconductor switch element according to a fifth embodiment of the present invention.

[0045] Figure 6 This is a circuit block diagram showing a drive circuit for a semiconductor switch element according to a sixth embodiment of the present invention and a semiconductor device having the drive circuit. DETAILED DESCRIPTION

[0046] Implementation method 1.

[0047] Figure 1 1 is a circuit block diagram showing a drive circuit 101 of a semiconductor switch element according to Embodiment 1 of the present invention. The drive circuit 101 is connected to a control terminal of the semiconductor switch element 1. The semiconductor switch element 1 according to Embodiment 1 is a MOSFET, and the control terminal is a gate terminal. The drive circuit and the semiconductor switch element 1 constitute a semiconductor device 151 according to Embodiment 1.

[0048] The driving circuit 101 includes an input circuit 3 connected to an input terminal 50 and an output control circuit 4 connected to the input circuit 3. The pulse signal output by the output control circuit 4 is input to the dead time adjustment circuit 13. The dead time adjustment circuit 13 includes a delay circuit. The delay circuit can delay the rising edge and the falling edge of the pulse signal output by the output control circuit 4 and output it to the subsequent stage of the dead time adjustment circuit 13.

[0049] The output of the dead time adjustment circuit 13 is input to the drive circuit 5. The drive circuit 5 outputs a drive signal to the output terminal 51 of the drive circuit 101. Thus, the drive circuit 5 can drive the semiconductor switch element 1.

[0050] The input circuit 3, the output control circuit 4, the dead time adjustment circuit 13, and the drive circuit 5 constitute a signal circuit 111 involved in the first embodiment. The signal circuit 111 generates a drive signal according to the input signal input to the input terminal 50, and supplies the drive signal to the output terminal 51. The drive signal has an on edge that is turned on in response to the rising edge of the input signal and an off edge that is turned off in response to the falling edge of the input signal. In a typical case, the on edge is a rising edge for turning on the semiconductor switch element 1. In a typical case, the off edge is a falling edge for turning off the semiconductor switch element 1.

[0051] The drive circuit 101 has an error control circuit 6, an overheat protection circuit 7, an internal power supply circuit 8, a temperature sensing diode 10, and temperature analog output circuits 11, 12. The drive circuit 101 has a power supply terminal 9 for obtaining a power supply voltage VCC.

[0052] The temperature analog output circuit 12 is connected to the temperature detection terminal 52 of the drive circuit 101. The temperature detection terminal 52 is connected to the temperature sensing diode 2 formed on the same semiconductor chip as the semiconductor switch element 1. The temperature sensing diode 2 can monitor the element temperature of the semiconductor switch element 1.

[0053] The temperature sensing diode 2 and the temperature sensing diode 10 each have a forward voltage temperature characteristic. The temperature analog output circuit 11 generates a first analog signal correlated with the temperature of the drive circuit 101 based on the output of the temperature sensing diode 10. In addition, the temperature analog output circuit 12 generates a second analog signal correlated with the element temperature of the semiconductor switch element 1 based on the output of the temperature sensing diode 2.

[0054] If the element temperature of the semiconductor switch element 1 rises beyond the normal range, the forward voltage of the temperature sensing diode 2 becomes less than or equal to the threshold value preset in the overheat protection circuit 7. In this case, the comparator output signal inside the overheat protection circuit 7 switches, and the switching of the signal is transmitted to the error control circuit 6.

[0055] If the signal from the overheat protection circuit 7 is switched, the error control circuit 6 transmits a stop signal to the output control circuit 4 to stop the driving of the semiconductor switch element 1. Since the output control circuit 4 receives the stop signal and stops the output, the overheat protection action is realized. In addition, the error control circuit 6 can also output an error signal to the outside via the error signal terminal 53.

[0056] The analog signals from the temperature analog output circuits 11 and 12 are input to the dead time adjustment circuit 13 .

[0057] After the rising edge of the input signal is transmitted to the input circuit 3, there is a time delay until the semiconductor switch element 1 is actually turned on. This is also called "on-transmission delay time". Similarly, after the falling edge of the input signal is transmitted to the input circuit 3, there is a time delay until the semiconductor switch element 1 is actually turned off. This is also called "off-transmission delay time".

[0058] If the temperature characteristics of the on-transmission delay time and the off-transmission delay time are different from each other, the difference between the on-transmission delay time and the off-transmission delay time will change when there is a temperature change. If the difference between the on-transmission delay time and the off-transmission delay time increases, there is a problem that the on-period of the input signal and the on-period of the drive signal deviate by the difference. Therefore, the dead time adjustment circuit 13 adjusts the difference between the on-transmission delay time and the off-transmission delay time based on the temperature information of the semiconductor switch element 1 and the temperature information of the drive circuit 101.

[0059] Specifically, the dead time adjustment circuit 13 delays at least one of the rising edge and the falling edge of the pulse output by the output control circuit 4 in order to reduce the difference between the on-transmission delay time and the off-transmission delay time. In order to make the shorter transmission delay time of the on-transmission delay time and the off-transmission delay time equal to the longer transmission delay time, the signal edge with a smaller delay may be delayed more than the signal edge with a larger delay.

[0060] Here, the amount of delay when the dead time adjustment circuit 13 (more specifically, the delay circuit included therein) delays the rising edge or falling edge of the output pulse of the output control circuit 4 is also referred to as "delay amount". It is preferable to appropriately determine the delay amount so that the difference between the on-transmission delay time and the off-transmission delay time is zero. It is preferable to determine the relationship between the values ​​of the first and second analog signals and the delay amount in such a manner that the difference between the on-transmission delay time and the off-transmission delay time can be zero or maintained within a predetermined allowable range even when there is a temperature change.

[0061] The delay amount is adjusted by the dead time adjustment circuit 13 receiving the first analog signal and the second analog signal adjusting the capacitance of the delay circuit therein. The dead time adjustment circuit 13 is designed to change the delay amount of the delay circuit in a predetermined proportional relationship in accordance with the values ​​of the first analog signal and the second analog signal. The relationship between the first analog signal and the delay amount and the relationship between the second analog signal and the delay amount may be determined as follows.

[0062] (1) Relationship between the first analog signal and the delay amount

[0063] The first analog signal is correlated with the temperature of the drive circuit 101. If the temperature of the drive circuit 101 rises, the on-transmission delay time and the off-transmission delay time increase accordingly. If the temperature characteristics of the on-transmission delay time and the off-transmission delay time are different from each other, when the temperature of the drive circuit 101 rises to a certain level, the increase in the on-transmission delay time and the increase in the off-transmission delay time are different from each other. According to the difference in these increases, the signal edge with the smaller increase between the on edge and the off edge can be delayed. As a result, when there is a certain temperature change, the on-transmission delay time and the off-transmission delay time can be changed by the same amount.

[0064] For example, when the increase in the off-transmission delay time is large, the signal edge for turning on the semiconductor switch element 1 (specifically, the rising edge of the input pulse waveform to the drive circuit 5) is delayed in accordance with the difference between the increase in the on-transmission delay time and the increase in the off-transmission delay time when there is a certain temperature rise. The proportional relationship between the temperature of the drive circuit 101 and the delay amount can be determined by investigating in advance the increase in the on-transmission delay time and the increase in the off-transmission delay time corresponding to the temperature change of the drive circuit 101. In addition, the so-called "proportional relationship" here is not limited to a proportional relationship of simple increase or simple decrease according to a linear function. The so-called "proportional relationship" here also includes a relationship in which the delay amount is increased or decreased in a curve relative to the temperature change according to a quadratic function or a higher-order function.

[0065] (2) Relationship between the second analog signal and the delay amount

[0066] The second analog signal is correlated with the device temperature of the semiconductor switch element 1. The on-propagation delay time and the off-propagation delay time vary not only according to the temperature of the drive circuit 101 but also according to the device temperature of the semiconductor switch element 1. The input capacitance is correlated with the device temperature of the semiconductor switch element 1 and has either a positive temperature characteristic or a negative temperature characteristic.

[0067] If the load capacitance, that is, the input capacitance of the semiconductor switch element 1 in the first embodiment, increases, the on-propagation delay time and the off-propagation delay time increase accordingly. The drive circuit 5 has an output current capability (current sourcing capability) for charging the input capacitance and an output current capability (current sinking capability) for discharging the input capacitance. When the current sourcing capability and the current sinking capability are different, the amount of change in the on-propagation delay time and the amount of change in the off-propagation delay time when the input capacitance changes are different.

[0068] As described above, there is a problem that if the element temperature changes, the input capacitance changes, and if the input capacitance changes, the difference between the on-transmission delay time and the off-transmission delay time changes. Specifically, the smaller the output current capability is, the greater the change in the transmission delay time corresponding to the change in input capacitance is. Therefore, in Embodiment 1, assuming that the charging capability is higher than the discharging capability, the delay circuit is controlled in the following manner.

[0069] When the input capacitance has a positive temperature characteristic, that is, when the input capacitance increases in accordance with a temperature rise, the delay amount is determined as follows.

[0070] First, when the element temperature rises, the increase in the OFF propagation delay time is greater than the increase in the ON propagation delay time. Therefore, the delay circuit of the dead time adjustment circuit 13 delays the signal edge for turning on the semiconductor switch element 1 (specifically, the rising edge of the input pulse waveform to the drive circuit 5) by the difference between the OFF propagation delay time and the ON propagation delay time.

[0071] On the contrary, when the element temperature decreases, the decrease in the OFF-transmission delay time is greater than the decrease in the ON-transmission delay time. Therefore, the delay circuit of the dead time adjustment circuit 13 delays the signal edge for turning off the semiconductor switch element 1 (specifically, the falling edge of the input pulse waveform to the drive circuit 5) by the difference between the OFF-transmission delay time and the ON-transmission delay time.

[0072] On the other hand, when the input capacitance has a negative temperature characteristic, that is, when the input capacitance decreases in response to a temperature increase, the delay amount is determined as follows.

[0073] First, when the element temperature rises, the amount of decrease in the OFF-transmission delay time is greater than the amount of decrease in the ON-transmission delay time. Therefore, the delay circuit of the dead time adjustment circuit 13 delays the signal edge for turning off the semiconductor switch element 1 (specifically, the falling edge of the input pulse waveform to the drive circuit 5) by the difference between the OFF-transmission delay time and the ON-transmission delay time.

[0074] On the contrary, when the element temperature decreases, the increase in the OFF propagation delay time is greater than the increase in the ON propagation delay time. Therefore, the delay circuit of the dead time adjustment circuit 13 delays the signal edge for turning on the semiconductor switch element 1 (specifically, the rising edge of the input pulse waveform to the drive circuit 5) by the difference between the OFF propagation delay time and the ON propagation delay time.

[0075] The dead time adjustment circuit 13 may be designed such that the final delay amount and the signal edge to be delayed are determined in advance by adding the delay amounts (1) and (2) described above, and the signal edge to be delayed is delayed according to the delay amount.

[0076] As described above, the drive circuit 101 uses both the first analog signal and the second analog signal to suppress the change in the difference between the OFF propagation delay time and the ON propagation delay time of the drive circuit 101. Since the semiconductor switch element 1 and the drive circuit 101 each have temperature characteristics, the overall circuit operation of the semiconductor device 151 can be optimized by utilizing the temperature information of both.

[0077] Furthermore, in Embodiment 1, the dead time adjustment circuit 13 is controlled based on both the first analog signal and the second analog signal. However, the present invention is not limited to this.

[0078] Alternatively, only the first analog signal may be input to the dead time adjustment circuit 13. In this case, only the delay amount correction according to the above-mentioned "(1) Relationship between the first analog signal and the delay amount" may be performed. In this case, the circuit related to the second analog signal (i.e., the temperature analog output circuit 12) may be omitted.

[0079] Alternatively, the dead time adjustment circuit 13 may be controlled using only the second analog signal. In this case, only the delay amount correction according to the above-mentioned "(2) Relationship between the second analog signal and the delay amount" may be performed. In this case, the temperature sensing diode 10 and the temperature analog output circuit 11 may be omitted.

[0080] Implementation method 2.

[0081] Figure 2 1 is a circuit block diagram showing a semiconductor switch element drive circuit 102 according to Embodiment 2 of the present invention. In the drive circuit 102 and the signal circuit 112, there is no dead time adjustment circuit 13, and a drive circuit 25 is provided instead of the drive circuit 5. Except for this point, the drive circuit 102 and the signal circuit 112 have the same circuit configuration as the drive circuit 101 and the signal circuit 111, respectively. The drive circuit 102 and the semiconductor switch element 1 constitute a semiconductor device 152 according to Embodiment 2.

[0082] The driving circuit 25 has a plurality of output-stage transistors, which are connected in parallel to form a plurality of current paths in parallel. Thus, the more output-stage transistors are turned on among the plurality of output-stage transistors, the greater the current that can flow. That is, the driving current capability can be increased.

[0083] The drive circuit 25 receives the first analog signal from the temperature analog output circuit 11 and the second analog signal from the temperature analog output circuit 12. The drive circuit 25 is designed to turn on a predetermined number of output-stage transistors according to the values ​​of the first analog signal and the second analog signal.

[0084] In most cases, the output current of the drive circuit has a temperature characteristic, and typically has a negative temperature characteristic. When the drive current capability has a negative temperature characteristic, the drive current capability decreases at high temperatures and increases at low temperatures. There is a problem that the switching loss of the semiconductor switch element driven by the drive circuit changes with the change of such drive current capability.

[0085] In this regard, the driver circuit 25 increases the number of output stage transistors based on the first analog signal as the temperature of the driver circuit 102 increases. This can increase the drive current capability of the driver circuit 25 and reduce the variation in the drive current capability when the temperature of the driver circuit 102 rises.

[0086] In addition, as described in Embodiment 1, the input capacitance of the semiconductor switch element 1 also has a temperature characteristic. When the input capacitance changes, it is preferable to adjust the driving current capability of the drive circuit 25 accordingly. Therefore, the drive circuit 25 is configured to change the number of output-stage transistors to be turned on in proportion to the element temperature represented by the second analog signal.

[0087] When the input capacitance has a positive temperature characteristic, that is, when the input capacitance increases with the temperature rise, the number of output stage transistors turned on is set to be large in order to increase the driving current capability with the increase in the element temperature. Conversely, when the input capacitance has a negative temperature characteristic, that is, when the input capacitance decreases with the temperature rise, the number of output stage transistors turned on is set to be small in order to reduce the driving current capability with the increase in the element temperature.

[0088] According to the above tendency, the driving circuit 25 may be designed by determining in advance the final number of output-stage transistors to be turned on corresponding to the temperature of the driving circuit 102 indicated by the first analog signal and the device temperature indicated by the second analog signal.

[0089] According to the second embodiment described above, even when temperature changes occur, it is possible to suppress the change in on-off loss by suppressing the change in the driving current capability of the driving circuit 25. In particular, according to the second embodiment, since both the element temperature information of the semiconductor switch element 1 and the temperature information of the driving circuit 102 are input to the driving circuit 25, it is possible to turn on the optimal number of output stage transistors by considering both the temperature characteristics of the input capacitance and the temperature characteristics of the driving current capability.

[0090] Furthermore, in Embodiment 2, the drive circuit 25 is controlled based on both the first analog signal and the second analog signal. However, the present invention is not limited to this.

[0091] Alternatively, only the first analog signal may be input to the drive circuit 25. In this case, based on the first analog signal, the higher the temperature of the drive circuit 102 is, the more output stage transistors are used. In this case, the circuit related to the second analog signal (i.e., the temperature analog output circuit 12) may be omitted.

[0092] Alternatively, only the second analog signal may be input to the drive circuit 25. In this case, as described above, the number of output stage transistors to be turned on may be changed in proportion to the element temperature represented by the second analog signal. In this case, the temperature sensing diode 10 and the temperature analog output circuit 11 may be omitted.

[0093] Implementation method 3.

[0094] Figure 3 1 is a circuit block diagram showing a drive circuit 103 of a semiconductor switch element according to Embodiment 3 of the present invention. The drive circuit 103 does not have a dead time adjustment circuit 13, but has a short circuit protection circuit 33. Except for this point, the drive circuit 103 has the same circuit structure as the drive circuit 101. The drive circuit 103 and the semiconductor switch element 1 constitute a semiconductor device 153 according to Embodiment 3. The input circuit 3, the output control circuit 4, and the drive circuit 5 constitute a signal circuit 113 according to Embodiment 3.

[0095] The short-circuit protection circuit 33 is a circuit for performing a protective action such as stopping the semiconductor switch element 1 when the main current flowing through the semiconductor switch element 1 exceeds a certain level. Although not shown in the figure, there is a method for detecting the main current flowing through the semiconductor switch element, that is, a part of the main current is shunted to a current detection element (unit) connected in parallel with the switch element, and the shunted current (sensing current) is detected. The sensing current is converted into a voltage (sensing voltage) using a resistor or the like, and input to the short-circuit protection circuit 33 via the short-circuit protection terminal 54. When the sensing voltage input to the short-circuit protection terminal 54 exceeds a specified threshold voltage, the short-circuit protection circuit 33 determines that an overcurrent has flowed through the semiconductor switch element 1 and performs a protective action.

[0096] The drive circuit 103 can also obtain temperature information of the semiconductor switch element 1 and the drive circuit 103 through the first and second analog signals from the temperature analog output circuits 11 and 12. This temperature information is input to the short-circuit protection circuit 33, and the short-circuit protection circuit 33 adjusts the threshold voltage of the short-circuit protection.

[0097] The short-circuit protection circuit 33 has a voltage divider circuit 34 therein for generating a threshold voltage from the internal power supply circuit 8. The voltage divider resistance value of the voltage divider circuit 34 is variably set in accordance with the values ​​of the first and second analog signals. The threshold voltage is adjusted in accordance with the values ​​of the first and second analog signals in accordance with a proportional relationship predetermined in circuit design.

[0098] The threshold voltage of the short-circuit protection has a positive temperature characteristic, and the higher the temperature of the drive circuit 103, the higher the threshold voltage. In addition, the short-circuit tolerance of the semiconductor switch element 1 varies according to the element temperature. Since the current capacity decreases as the element temperature becomes high, it is preferable to perform short-circuit protection with a lower threshold voltage. Therefore, it is preferable to set the threshold voltage of the short-circuit protection variably according to these temperatures.

[0099] In this embodiment, in order to perform correction of these temperature characteristics, first, the element temperature represented by the second analog signal is correlated with the set value of the threshold voltage, and the set value of the threshold voltage is calculated based on the second analog signal. In conjunction with this, the threshold voltage increase amount depending on the temperature characteristics of the drive circuit 103 can be calculated based on the first analog signal, and in order to offset it, the threshold voltage is adjusted by changing the resistance voltage division ratio of the voltage divider circuit 34. The threshold voltage setting performed using both the first and second analog signals as described above is preferably performed in all temperature ranges including low temperature, normal temperature, and high temperature.

[0100] The short-circuit protection circuit 33 is also connected to the error control circuit 6. The error control circuit 6 adjusts the response time, which is the response time until the error signal output to the outside via the error signal terminal 53 is output according to the signal from the short-circuit protection circuit 33. The error signal is a signal for outputting to other semiconductor switch elements and drive circuits that are turned on and off in a phase different from that of the semiconductor switch element 1, or outputting to an external microcomputer, etc., to prompt the outside of the protection action.

[0101] Since the output response time of the error signal has a positive temperature characteristic, the higher the temperature of the drive circuit 103, the longer the output response time. Therefore, even if the threshold voltage is the same, it becomes easy to cause short-circuit damage to the semiconductor switch element 1. Therefore, in order to correct the temperature characteristic, the maximum temperature of the drive circuit 103 assumed based on the first analog signal and the second analog signal is calculated, and the connection capacitor of the delay circuit built into the error control circuit 6 or the delay circuit external to the error control circuit 6 is switched, thereby reducing the output response time of the amount increased due to the temperature rise. In this way, the temperature characteristic of the output response time can be adjusted.

[0102] According to the third embodiment described above, it is possible to suppress the change of the short-circuit protection condition caused by the temperature change of the drive circuit 103 and the element temperature change. As a result, it is possible to suppress the short-circuit protection condition of the semiconductor device 153 from changing in accordance with the temperature. In particular, according to the third embodiment, since both the first and second analog signals are input to the short-circuit protection circuit 33, it is possible to optimize the threshold voltage and the output response time by considering both the element temperature information of the semiconductor switch element 1 and the temperature information of the drive circuit 102.

[0103] In addition, in Embodiment 3, the threshold voltage and the error signal response time of the short-circuit protection circuit 33 are adjusted based on both the first analog signal and the second analog signal. However, the present invention is not limited to this. It is also possible to adjust only one of the threshold voltage and the error signal response time of the short-circuit protection circuit 33.

[0104] Alternatively, only the first analog signal may be input to the short-circuit protection circuit 33. In this case, the threshold voltage increase amount depending on the temperature characteristics of the drive circuit 103 is calculated based on the first analog signal, and in order to offset it, the threshold voltage may be lowered by changing the resistance voltage division ratio of the voltage divider circuit 34. In this case, the circuit related to the second analog signal (i.e., the temperature analog output circuit 12) may be omitted.

[0105] Alternatively, only the second analog signal may be input to the short-circuit protection circuit 33. In this case, as described above, the element temperature represented by the second analog signal is correlated with the threshold voltage, and the threshold voltage is set so that short-circuit protection is performed at a lower threshold voltage as the element temperature becomes higher. In this case, the temperature sensing diode 10 and the temperature analog output circuit 11 may be omitted.

[0106] Implementation method 4.

[0107] Figure 4 1 is a circuit block diagram showing a drive circuit 104 of a semiconductor switch element according to a fourth embodiment of the present invention. The drive circuit 104 includes an AD conversion circuit 14, an operation circuit 15, a comparator 16, a monitoring output unit 17, and an allowable temperature difference setting circuit 18, and does not include a dead time adjustment circuit 13. Except for this point, the drive circuit 104 has the same circuit structure as the drive circuit 101. The drive circuit 104 and the semiconductor switch element 1 constitute a semiconductor device 154 according to the fourth embodiment. In addition, the drive circuit 104 has a signal circuit 113, which is composed of an input circuit 3, an output control circuit 4, and a drive circuit 5, as in the third embodiment.

[0108] The AD conversion circuit 14 performs AD conversion on the first analog signal and the second analog signal obtained from the temperature analog output circuit 11 and the temperature analog output circuit 12. The operation circuit 15 calculates the difference between the element temperature of the semiconductor switch element 1 and the temperature of the drive circuit 104, which are expressed as digital values ​​by AD conversion by the AD conversion circuit 14, and calculates the difference, that is, the temperature difference ΔT. The comparator 16 outputs an error signal when the temperature difference ΔT input to the negative input terminal is smaller than the voltage input to the positive input terminal.

[0109] The AD conversion circuit 14 and the operation circuit 15 are connected to the monitoring output unit 17 outside the drive circuit 104. The element temperature, the temperature of the drive circuit 104, and the temperature difference ΔT are displayed on the monitoring output unit 17, and the user can visually confirm these information. The allowable temperature difference setting circuit 18 can set the allowable value of the temperature difference ΔT as the input voltage value of the comparator 16.

[0110] The driving circuit 104 has a three-input AND circuit 40. The output signal of the comparator 16, the output signal of the overheat protection circuit 7, and the output signal of the output control circuit 4 are input to the AND circuit 40. Only when these three input signals are present, the overheat protection signal is transmitted to the error control circuit 6. Thus, in a non-high temperature state, or in a state where there is no input signal to the input circuit 3 and the driving circuit 104 is not operating, the error signal from the comparator 16 can be shielded.

[0111] By calculating the temperature difference ΔT, the comparator 16 can determine whether the cooling structure of the semiconductor device 154 meets the design with respect to the element temperature of the semiconductor switch element 1. When the temperature difference ΔT is smaller than the specified value, the temperature of the drive circuit 104 is too close to the element temperature of the semiconductor switch element 1. Generally, the temperature of the drive circuit 104 is lower than the element temperature by a certain degree or more, so when the temperature difference ΔT is smaller than the specified value, it can be expected that the cooling structure fails to exert the designed cooling performance. In this case, the signal is transmitted from the comparator 16 to the error control circuit 6, and an error signal is output from the error signal terminal 53.

[0112] According to the fourth embodiment described above, fluctuations in the cooling structure can be detected, and information for protecting the semiconductor device 154 can be acquired.

[0113] Implementation method 5.

[0114] Figure 5 1 is a circuit block diagram showing a drive circuit of a semiconductor switch element according to Embodiment 5 of the present invention. In the drive circuit 105, an identification circuit 19 is provided instead of the comparator 16. In addition, the monitoring output unit 17 and the allowable temperature difference setting circuit 18 are not connected. Except for this point, the drive circuit 105 has the same circuit structure as the drive circuit 104. The drive circuit 105 and the semiconductor switch element 1 constitute the semiconductor device 155 according to Embodiment 5. In addition, the drive circuit 105 has a signal circuit 113, which is composed of an input circuit 3, an output control circuit 4, and a drive circuit 5, as in Embodiment 3.

[0115] Similar to the fourth embodiment, the temperatures of the semiconductor switch element 1 and the drive circuit 105 are converted into digital values ​​by the AD conversion circuit 14 , and the calculation circuit 15 calculates the temperature difference ΔT. The temperature difference ΔT calculated by the calculation circuit 15 is input to the identification circuit 19 .

[0116] The identification circuit 19 compares the value of the temperature difference ΔT with a comparison value stored internally. Specifically, the first comparison value T is set when the cooling structure of the semiconductor device 155 is designed. A and the second comparison value T B , the normal range of the temperature difference ΔT in the cooling structure design is set to T A ≤ΔT≤T B When set to 0<T A <T B In the case of , the abnormality occurrence location can be determined as follows. In the fifth embodiment, the specific numerical value of the temperature difference ΔT is a value obtained by subtracting the temperature of the drive circuit 105 from the element temperature of the semiconductor switch element 1 .

[0117] (Abnormality 1) When ΔT<0, it is suspected that there is abnormality such as abnormal heating of the drive circuit 105 or a short circuit at the output stage of the drive circuit 5 .

[0118] (Exception 2) When 0≤ΔT<T A It is suspected that there is an abnormality in the cooling structure of the semiconductor device 155.

[0119] (Exception 3) In T B When <ΔT, it is suspected that there is abnormality such as abnormal heating of the semiconductor switch element 1 or short circuit between the drain and the source of the semiconductor switch element 1 .

[0120] When an IGBT or a bipolar transistor is used as the semiconductor switch element 1, B When <ΔT, there may be a short circuit between the collector and emitter.

[0121] The identification circuit 19 outputs a plurality of error signals for determining the abnormality occurrence position, which are set in advance, according to the magnitude of the temperature difference ΔT. The error signals are input to the error control circuit 6 via the AND circuit 40 .

[0122] The identification circuit 19 is designed to be able to output at least three different error signals. These three error signals are respectively assigned to the above-mentioned abnormalities 1 to 3. In this embodiment, it is assumed that the identification circuit 19 outputs three error signals with different duty ratios, and the error signals are input to the error control circuit 6, and the error control circuit 6 outputs the three error signals with different duty ratios to the error signal terminal 53. As a result, the user can identify abnormalities 1 to 3 via the error signal terminal 53.

[0123] As described above, according to the fifth embodiment, it is possible to detect the abnormality occurrence location of the semiconductor device 155 based on the temperature difference ΔT between the semiconductor switch element 1 and the drive circuit 105 .

[0124] Implementation method 6.

[0125] Figure 6 1 is a circuit block diagram showing a semiconductor switch element drive circuit 103 according to Embodiment 6 of the present invention and a semiconductor device 156 having the drive circuit 103. The difference from Embodiment 3 is that the semiconductor device 156 has a semiconductor switch element 20. The drive circuit 103 that drives the semiconductor switch element 20 is the same as that of Embodiment 3.

[0126] The semiconductor switch element 20 is a switch element using SiC (silicon carbide) as a semiconductor material. SiC devices using SiC as a semiconductor material have excellent electrical and thermal characteristics.

[0127] Furthermore, in the sixth embodiment, the semiconductor switch element 20 is connected to the drive circuit 103 , but the present invention is not limited thereto. A semiconductor device in which the semiconductor switch element 20 is connected to any of the drive circuits 101 , 102 , and 104 to 105 may be provided.

[0128] In addition, various semiconductor materials and element structures can be applied to the semiconductor switch element 1 . For example, an IGBT formed of silicon or a power MOSFET formed of silicon may be used.

[0129] It is also possible to arbitrarily combine two or more of the technical features of the drive circuits 101 to 105 and semiconductor devices 151 to 156 involved in the above-described embodiments 1 to 6. Specifically, it is also possible to arbitrarily select two or more structures from the group consisting of the following structures A to F, and set the selected two or more structures in one drive circuit or one semiconductor device.

[0130] (Structure A) Dead time adjustment circuit 13 according to embodiment 1

[0131] (Structure B) Driving Circuit 25 According to Embodiment 2

[0132] (Structure C) Short-circuit protection circuit 33 and voltage dividing circuit 34 according to Embodiment 3

[0133] (Configuration D) AD conversion circuit 14, operation circuit 15, comparator 16, monitor output unit 17, allowable temperature difference setting circuit 18, and AND circuit 40 according to Embodiment 4

[0134] (Structure E) Identification Circuit 19 According to Embodiment 5

[0135] (Structure F) Semiconductor switch element 20 according to Embodiment 6

[0136] Description of the label

[0137] 1, 20 semiconductor switch element, 2 temperature sensing diode, 3 input circuit, 4 output control circuit, 5, 25 drive circuit, 6 error control circuit, 7 overheat protection circuit, 8 internal power supply circuit, 9 power supply terminal, 10 temperature sensing diode, 11, 12 temperature analog output circuit, 13 dead time adjustment circuit, 14 AD conversion circuit, 15 operation circuit, 16 comparator, 17 monitoring output unit, 18 allowable temperature difference setting circuit, 19 identification circuit, 33 short circuit protection circuit, 34 voltage divider circuit, 40 AND circuit, 50 input terminal, 51 output terminal, 52 temperature detection terminal, 53 error signal terminal, 54 short circuit protection terminal, 101, 102, 103, 104, 105 drive circuit, 111, 112, 113 signal circuit, 151, 152, 153, 154, 155, 156 semiconductor device.

Claims

1. A driving circuit for a semiconductor switch element, comprising: an input terminal to which an input signal is input; an output terminal connected to a control terminal of the semiconductor switching element; a signal circuit unit that generates a driving signal according to the input signal and supplies the driving signal to the output terminal; a temperature detection unit including a first temperature detection unit that outputs a first temperature detection signal having a correlation with the temperature of the signal circuit unit and a second temperature detection unit that receives a second temperature detection signal from a temperature sensor element that detects the temperature of the semiconductor switch element; Short circuit protection terminal; as well as The short-circuit protection circuit transmits a stop signal to the signal circuit unit if a voltage input to the short-circuit protection terminal reaches a threshold value, and the short-circuit protection circuit sets the threshold value based on both the first temperature detection signal and the second temperature detection signal.

2. A driving circuit for a semiconductor switch element, comprising: an input terminal to which an input signal is input; an output terminal connected to a control terminal of the semiconductor switching element; a signal circuit unit that generates a driving signal according to the input signal and supplies the driving signal to the output terminal; a temperature detection circuit which outputs a first temperature detection signal having a correlation with the temperature of the signal circuit portion; a temperature detection terminal receiving a second temperature detection signal from a temperature sensor element of the semiconductor switch element; as well as The error signal generating circuit outputs an error signal when the difference between the temperature indicated by the first temperature detection signal and the temperature indicated by the second temperature detection signal is smaller than a predetermined value.

3. The semiconductor switch element drive circuit according to claim 2, wherein: The error signal generating circuit switches between a plurality of mutually different error signals corresponding to respective values ​​of the temperature difference based on the value of the temperature difference.

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