JP2018198460A - Drive circuit for semiconductor switching element - Google Patents

Abstract

To provide a drive circuit for a semiconductor switching element capable of reflecting temperature information in operation of the drive circuit with accuracy.SOLUTION: A drive circuit for a semiconductor switching element comprises: an input terminal to which an input signal is inputted; an output terminal connected with a control terminal of the semiconductor switching element; a signal circuit part that generates a drive signal from the input signal and supplies the drive signal to the output terminal; temperature detection means that includes both first temperature detection means that outputs a first temperature detection signal having a correlation with a temperature of the signal circuit part, and second temperature detection means that receives a second temperature detection signal from an element temperature sensor element for detecting a temperature of the semiconductor switching element; a short circuit protection terminal; and a short circuit protection circuit that transmits a stop signal to the signal circuit part when a voltage inputted to the short circuit protection terminal reaches a threshold, and sets the threshold on the basis of both the first temperature detection signal and the second temperature detection signal.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a drive circuit for a semiconductor switching element.

  Conventionally, in order to protect the switching element from overheating, various techniques such as limiting current supply control based on a temperature detected by a temperature sensor have been proposed. For example, as disclosed in Japanese Unexamined Patent Publication No. 2009-136061, a drive circuit that performs overheat protection or the like based on temperature information of a semiconductor switching element is known.

JP 2009-136061 A JP 2008-277433 A JP 2012-253202 A

  In the conventional typical semiconductor device, an overheat protection circuit is provided in the drive circuit for overheat protection of the semiconductor switching element. Specifically, a temperature sensor for temperature detection is provided in the semiconductor switching element. The overheat protection circuit compares the element temperature of the semiconductor switching 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 becomes too high. The operation of the overheat protection circuit is to alternatively stop the drive circuit depending on whether or not the element temperature has reached the threshold value.

  The semiconductor switching element has temperature characteristics. For example, the input capacitance changes according to the element temperature. Even in the drive circuit that drives the semiconductor switching element, the circuit operation is affected if the temperature inside the drive circuit changes. The temperature information that affects the circuit operation of the drive circuit is preferably reflected in the operation of the drive circuit in more detail.

  Further, as described above, an overheat protection technique for detecting the temperature of a single semiconductor switching element is known. The semiconductor switching element and its drive circuit usually have different temperatures during use of the semiconductor device due to the difference in the amount of heat generation and the cooling structure of the semiconductor device. The inventor of the present application has found a technique that can detect abnormality of a semiconductor device in more detail by using this temperature difference.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a semiconductor switching element driving circuit capable of accurately reflecting temperature information on the operation of the driving circuit.

The drive circuit for the semiconductor switching element according to the first invention is:
An input terminal to which an input signal is input;
An output terminal connected to the control terminal of the semiconductor switching element;
A signal circuit unit that generates a drive signal from the input signal and supplies the drive signal to the output terminal;
First temperature detection means for outputting a first temperature detection signal having a correlation with the temperature of the signal circuit section, and second temperature detection means for receiving a second temperature detection signal from an element temperature sensor element for detecting the temperature of the semiconductor switching element Temperature sensing means including both,
Short-circuit protection terminal;
A short circuit protection circuit that transmits a stop signal to the signal circuit unit when the voltage input to the short circuit protection terminal reaches a threshold value, and sets the threshold value based on both the first temperature detection signal and the second temperature detection signal. When,
Is provided.

The drive circuit for the semiconductor switching element according to the second invention is:
An input terminal to which an input signal is input;
An output terminal connected to the control terminal of the semiconductor switching element;
A signal circuit unit that generates a drive signal from the input signal and supplies the drive signal to the output terminal;
A temperature detection circuit that outputs a first temperature detection signal having a correlation with the temperature of the signal circuit unit;
A temperature detection terminal for receiving a second temperature detection signal from a temperature sensor element of the semiconductor switching element;
An error signal generation circuit that outputs an error signal based on a difference between the temperature indicated by the first temperature detection signal and the temperature indicated by the second temperature detection signal;
Is provided.

  According to the present invention, temperature information can be accurately reflected in the operation of the drive circuit using both the first temperature detection signal and the second temperature detection signal.

1 is a circuit block diagram showing a drive circuit for a semiconductor switching element according to a first embodiment of the present invention; It is a circuit block diagram which shows the drive circuit of the semiconductor switching element concerning Embodiment 2 of this invention. It is a circuit block diagram which shows the drive circuit of the semiconductor switching element concerning Embodiment 3 of this invention. FIG. 6 is a circuit block diagram illustrating a drive circuit for a semiconductor switching element according to a fourth embodiment of the present invention. FIG. 10 is a circuit block diagram illustrating a drive circuit for a semiconductor switching element according to a fifth embodiment of the present invention. FIG. 10 is a circuit block diagram showing a semiconductor switching element drive circuit and a semiconductor device including the same according to a sixth embodiment of the present invention.

Embodiment 1 FIG.
FIG. 1 is a circuit block diagram showing a drive circuit 101 for a semiconductor switching element according to a first embodiment of the present invention. The drive circuit 101 is connected to the control terminal of the semiconductor switching element 1. The semiconductor switching element 1 according to the first embodiment is a MOSFET, and the control terminal is a gate terminal. The drive circuit and the semiconductor switching element 1 constitute the semiconductor device 151 according to the first embodiment.

  The drive circuit 101 includes 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 from 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 falling edge of the pulse signal output from the output control circuit 4 and output the delayed signal to the subsequent stage of the dead time adjustment circuit 13.

  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. Thereby, the drive circuit 5 can drive the semiconductor switching element 1.

  The input circuit 3, the output control circuit 4, the dead time adjustment circuit 13, and the drive circuit 5 constitute the signal circuit 111 according to the first embodiment. The signal circuit 111 generates a drive signal from 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 a rising edge of the input signal and an off-edge that is turned off in response to a falling edge of the input signal. The on-edge is typically a rising edge for turning on the semiconductor switching element 1. The off edge is typically a falling edge for turning off the semiconductor switching element 1.

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

  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 a temperature sensing diode 2 formed on the same semiconductor chip as the semiconductor switching element 1. The temperature sense diode 2 can monitor the element temperature of the semiconductor switching element 1.

  The temperature sense diode 2 and the temperature sense diode 10 each have a temperature characteristic of a forward voltage. The temperature analog output circuit 11 generates a first analog signal having a correlation with the temperature of the drive circuit 101 from the output of the temperature sense diode 10. The temperature analog output circuit 12 generates a second analog signal having a correlation with the element temperature of the semiconductor switching element 1 based on the output of the temperature sense diode 2.

  When the element temperature of the semiconductor switching element 1 rises beyond the normal range, the forward voltage of the temperature sensing diode 2 becomes equal to or lower than a threshold value preset by the overheat protection circuit 7. In this case, the comparator output signal inside the overheat protection circuit 7 is switched, and the switching of the signal is transmitted to the error control circuit 6.

  The error control circuit 6 transmits a stop signal for stopping the driving of the semiconductor switching element 1 to the output control circuit 4 when the signal from the overheat protection circuit 7 is switched. The output control circuit 4 that has received the stop signal stops the output, thereby realizing the overheat protection operation. The error control circuit 6 can also output an error signal to the outside via the error signal terminal 53.

  Analog signals from the temperature analog output circuits 11 and 12 are input to the dead time adjustment circuit 13.

  After the rising edge of the input signal is transmitted to the input circuit 3, there is a time delay until the semiconductor switching element 1 is actually turned on. This is also referred to as “ON transmission delay time”. Similarly, there is a time delay until the semiconductor switching element 1 is actually turned off after the falling edge of the input signal is transmitted to the input circuit 3. This is also referred to as “off transmission delay time”.

  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 changes when there is a temperature change. When 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 are different from each other 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 switching element 1 and the temperature information of the drive circuit 101.

  Specifically, the dead time adjustment circuit 13 delays at least one of the rising edge and the falling edge of the pulse output from the output control circuit 4 so as to reduce the difference between the ON transmission delay time and the OFF transmission delay time. In order to make the shorter one of the on-transmission delay time and the off-transmission delay time equal to the longer transmission delay time, the edge with the smaller delay may be delayed more than the edge with the larger delay.

  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 described above is simply expressed as “ Also referred to as “delay amount”. By appropriately determining the delay amount, the difference between the on-transmission delay time and the off-transmission delay time is preferably made zero. It is preferable to define the relationship between the values of the first and second analog signals and the delay amount so that the difference between the on-transmission delay time and the off-transmission delay time can be maintained at zero or within a predetermined allowable range even when there is a temperature change. .

  The delay amount is adjusted by the dead time adjusting circuit 13 receiving the first analog signal and the second analog signal by adjusting the capacity of the internal delay circuit. The dead time adjustment circuit 13 is designed to change the delay amount by the delay circuit in a predetermined proportional relationship according to 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.

(1) Relationship between first analog signal and delay amount The first analog signal has a correlation with the temperature of the drive circuit 101. When 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 drive circuit 101 rises by a certain temperature, the increase amount of the on-transmission delay time and the increase amount of the off-transmission delay time are different from each other. . It is only necessary to delay the edge having the smaller increase amount between the on-edge and the off-edge by the difference between the increase amounts. 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.

  For example, when the increase amount of the off-transmission delay time is larger, the semiconductor switching element 1 is turned on by the difference between the increase amount of the on-transmission delay time and the increase amount of the off-transmission delay time when a certain temperature rises. (Specifically, the rising edge of the input pulse waveform to the drive circuit 5) is delayed. The proportional relationship between the temperature of the drive circuit 101 and the delay amount may be determined by examining the increase amount of the on-transmission delay time and the increase amount of the off-transmission delay time with respect to the temperature change of the drive circuit 101 in advance. The “proportional relationship” here is not limited to a proportional relationship that simply increases or decreases according to a linear function. Here, the “proportional relationship” includes a relationship in which the delay amount is increased or decreased according to a function of second order or higher, that is, in a curve with respect to the temperature change.

(2) Relationship between Second Analog Signal and Delay Amount The second analog signal has a correlation with the element temperature of the semiconductor switching element 1. The on-transmission delay time and the off-transmission delay time change not only with the temperature of the drive circuit 101 but also with the element temperature of the semiconductor switching element 1. The input capacitance has a correlation with the element temperature of the semiconductor switching element 1 and has either a positive temperature characteristic or a negative temperature characteristic.

  When the load capacity, that is, the input capacity of the semiconductor switching element 1 in the first embodiment is increased, the ON transmission delay time and the OFF transmission delay time are increased accordingly. The drive circuit 5 has an output current capability (source current capability) for charging the input capacitance and an output current capability (sink current capability) for discharging the input capacitance. When the source current capability and the sink current capability are different, the amount of change in the ON transmission delay time and the amount of change in the OFF transmission delay time when the input capacitance changes are different from each other.

  Thus, there is a problem that when the element temperature changes, the input capacitance changes, and when the input capacitance changes, the difference between the on transmission delay time and the off transmission delay time varies. Specifically, the smaller the output current capability, the greater the amount of change in the transmission delay time with respect to the change in input capacitance. Therefore, in the first embodiment, it is assumed that the charging capability is higher than the discharging capability, and the delay circuit is controlled as follows.

  When the input capacitance has a positive temperature characteristic, that is, when the input capacitance increases as the temperature rises, the delay amount is determined as follows.

  First, when the element temperature rises, the increase amount of the off transmission delay time is larger than the increase amount of the on transmission delay time. Therefore, the delay circuit of the dead time adjustment circuit 13 has an edge for turning on the semiconductor switching element 1 by the difference between the off transmission delay time and the on transmission delay time (specifically, the waveform of the input pulse to the drive circuit 5). Delay rising edge).

  Conversely, when the element temperature decreases, the amount of decrease in the off transmission delay time is larger than the amount of decrease in the on transmission delay time. Therefore, the delay circuit of the dead time adjusting circuit 13 has an edge for turning off the semiconductor switching element 1 by the difference between the off transmission delay time and the on transmission delay time (specifically, the waveform of the input pulse to the drive circuit 5). Delay the falling edge).

  On the other hand, when the input capacitance has a negative temperature characteristic, that is, when the input capacitance decreases as the temperature rises, the delay amount is determined as follows.

  First, when the element temperature rises, the decrease amount of the off transmission delay time is larger than the decrease amount of the on transmission delay time. Therefore, the delay circuit of the dead time adjusting circuit 13 has an edge for turning off the semiconductor switching element 1 by the difference between the off transmission delay time and the on transmission delay time (specifically, the waveform of the input pulse to the drive circuit 5). Delay the falling edge).

  On the contrary, when the element temperature decreases, the increase amount of the off transmission delay time is larger than the increase amount of the on transmission delay time. Therefore, the delay circuit of the dead time adjustment circuit 13 has an edge for turning on the semiconductor switching element 1 by the difference between the off transmission delay time and the on transmission delay time (specifically, the waveform of the input pulse to the drive circuit 5). Delay rising edge).

  The final delay amount and the edge to be delayed are determined in advance by adding the delay amount of (1) and the delay amount of (2) described above, and the dead time is set so that the delay target edge is delayed by the delay amount. The time adjustment circuit 13 may be designed.

  As described above, the drive circuit 101 uses both the first analog signal and the second analog signal to suppress a change in the difference between the off-transmission delay time and the on-transmission delay time of the drive circuit 101. . Since the semiconductor switching element 1 and the drive circuit 101 each have temperature characteristics, the circuit operation of the entire semiconductor device 151 can be optimized by using both pieces of temperature information.

  In the first embodiment, 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.

  Only the first analog signal may be input to the dead time adjustment circuit 13. In this case, it is only necessary to correct the delay amount in accordance with the above-mentioned “(1) Relationship between the first analog signal and the delay amount”. In this case, the circuit related to the second analog signal (that is, the temperature analog output circuit 12) may be omitted.

  Alternatively, the dead time adjustment circuit 13 may be controlled using only the second analog signal. In this case, it is only necessary to correct the delay amount according to the above-mentioned “(2) Relationship between the second analog signal and the delay amount”. In that case, the temperature sensing diode 10 and the temperature analog output circuit 11 may be omitted.

Embodiment 2. FIG.
FIG. 2 is a circuit block diagram showing the drive circuit 102 for the semiconductor switching element according to the second embodiment of the present invention. The drive circuit 102 and the signal circuit 112 do not have the dead time adjustment circuit 13 but include a drive circuit 25 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 switching element 1 constitute a semiconductor device 152 according to the second embodiment.

  The drive circuit 25 includes a plurality of output stage transistors, and the plurality of output stage transistors are connected in parallel to form a plurality of current paths in parallel. As a result, the larger the number of output stage transistors that are turned on among the plurality of output stage transistors, the larger the current can flow. That is, the drive current capability can be increased.

  The drive circuit 25 receives the first analog signal from the temperature analog output circuit 11 and receives 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 value of the first analog signal and the value of the second analog signal.

  In many cases, the drive circuit has a temperature characteristic in the output current, and typically has a negative temperature characteristic. When the drive current capability has a negative temperature characteristic, the drive current capability decreases at a high temperature and the drive current capability increases at a low temperature. There is a problem that the switching loss of the semiconductor switching element driven by the drive circuit fluctuates due to such a change in driving current capability.

  In this regard, the drive circuit 25 increases the number of output stage transistors as the temperature of the drive circuit 102 increases based on the first analog signal. As a result, when the temperature of the drive circuit 102 rises, the drive current capability of the drive circuit 25 can be increased to reduce fluctuations in the drive current capability.

  Further, as described in the first embodiment, the input capacitance of the semiconductor switching element 1 also has temperature characteristics. When the input capacitance changes, it is preferable to adjust the drive current capability of the drive circuit 25 accordingly. Therefore, the drive circuit 25 changes the number of output stage transistors to be turned on in proportion to the element temperature indicated by the second analog signal.

  If the input capacitance has a positive temperature characteristic, that is, if the input capacitance increases as the temperature rises, increase the number of output stage transistors that are turned on to improve the drive current capability as the element temperature rises. Set. Conversely, when the input capacitance has a negative temperature characteristic, that is, when the input capacitance decreases as the temperature increases, the output stage transistor that turns on so as to decrease the drive current capability as the element temperature increases. Set a smaller number.

  In accordance with the above tendency, the drive circuit 25 is designed by determining in advance the final number of output stage transistors according to the temperature of the drive circuit 102 indicated by the first analog signal and the element temperature indicated by the second analog signal. That's fine.

  According to the second embodiment described above, the switching loss fluctuation can be suppressed by suppressing the driving current capability fluctuation of the drive circuit 25 even when the temperature change occurs. In particular, according to the second embodiment, since both the element temperature information of the semiconductor switching element 1 and the temperature information of the drive circuit 102 are input to the drive circuit 25, the temperature characteristics of the input capacitance and the temperature characteristics of the drive current capability Considering both, an optimum number of output stage transistors can be turned on.

  In the second embodiment, 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.

  Only the first analog signal may be input to the drive circuit 25. In this case, the number of output stage transistors may be increased based on the first analog signal as the temperature of the drive circuit 102 increases. In this case, the circuit related to the second analog signal (that is, the temperature analog output circuit 12) may be omitted.

  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 indicated by the second analog signal. In this case, the temperature sensing diode 10 and the temperature analog output circuit 11 may be omitted.

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

  The short circuit protection circuit 33 is a circuit for performing a protection operation such as stopping the semiconductor switching element 1 when the main current flowing through the semiconductor switching element 1 exceeds a certain level. Although not shown, in the method for detecting the main current flowing in the semiconductor switching element, a part of the main current is shunted to a current detecting element (cell) connected in parallel with the switching element, and the shunt current (sense current) There is something to detect. This sense current is converted into a voltage (sense voltage) using a resistor or the like, and is input to the short circuit protection circuit 33 via the short circuit protection terminal 54. The short circuit protection circuit 33 determines that an overcurrent has flowed through the semiconductor switching element 1 when the sense voltage input to the short circuit protection terminal 54 exceeds a predetermined threshold voltage, and performs a protection operation.

  Also in the drive circuit 103, temperature information of the semiconductor switching element 1 and the drive circuit 103 can be acquired by the first and second analog signals from the temperature analog output circuits 11 and 12. These 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.

  The short circuit protection circuit 33 includes therein a voltage dividing circuit 34 for generating a threshold voltage from the internal power supply circuit 8. The voltage dividing resistance value of the voltage dividing circuit 34 is variably set according to the values of the first and second analog signals. In accordance with the values of the first and second analog signals, the threshold voltage is adjusted according to a proportional relationship predetermined in circuit design.

The threshold voltage for short circuit protection has a positive temperature characteristic, and the threshold voltage increases as the temperature of the drive circuit 103 increases. Further, the short-circuit tolerance of the semiconductor switching element 1 varies depending on the element temperature, and the current capability decreases as the element temperature increases. Therefore, it is preferable to perform short-circuit protection with a lower threshold voltage. Therefore, it is preferable to variably set the threshold voltage for short-circuit protection according to these temperatures.
In this embodiment, in order to perform correction for these temperature characteristics, first, a correlation is set between the element temperature indicated by the second analog signal and the set value of the threshold voltage, and based on the second analog signal. A set value of the threshold voltage is calculated. In addition, the threshold voltage increase due to the temperature characteristic of the drive circuit 103 is calculated based on the first analog signal, and the threshold voltage is adjusted by changing the resistance voltage dividing ratio of the voltage dividing circuit 34 so as to cancel this. be able to. Such a threshold voltage setting using both the first and second analog signals is preferably performed in all temperature ranges including a low temperature, a normal temperature, and a high temperature.

The short circuit protection circuit 33 is also connected to the error control circuit 6. The error control circuit 6 adjusts the response time until an error signal output to the outside is output via the error signal terminal 53 in accordance with a signal from the short circuit protection circuit 33. This error signal is output to another semiconductor switching element and a drive circuit that are switched in a phase different from that of the semiconductor switching element 1 or is output to an external microcomputer or the like to promote a protective operation to the outside. It is a signal for.
Since the error signal output response time 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, the semiconductor switching element 1 is likely to be short-circuit broken. Therefore, in order to correct this temperature characteristic, the maximum temperature of the driving circuit 103 assumed from the first analog signal and the second analog signal is calculated, and the delay circuit or the error control circuit 6 built in the error control circuit 6 is calculated. By switching the connection capacity of the external delay circuit, the output response time corresponding to the increase in temperature is reduced. Thereby, it is possible to adjust the temperature characteristic of output response time.

  According to the third embodiment described above, it is possible to suppress fluctuations in the short-circuit protection conditions caused by the temperature change of the drive circuit 103 and the element temperature change. Thereby, it can suppress that the short circuit protection conditions of the semiconductor device 153 change according to 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, both the element temperature information of the semiconductor switching element 1 and the temperature information of the drive circuit 102 are taken into consideration. The threshold voltage and output response time can be optimized.

  In the third embodiment, the threshold voltage and 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. Only one of the threshold voltage of the short circuit protection circuit 33 and the error signal response time may be adjusted.

  Only the first analog signal may be input to the short circuit protection circuit 33. In this case, the threshold voltage increase due to the temperature characteristic of the drive circuit 103 is calculated based on the first analog signal, and the threshold voltage may be reduced by changing the resistance voltage dividing ratio of the voltage dividing circuit 34 so as to cancel this. . In this case, the circuit related to the second analog signal (that is, the temperature analog output circuit 12) may be omitted.

  Alternatively, only the second analog signal may be input to the short circuit protection circuit 33. In this case, as described above, there is a correlation between the element temperature indicated by the second analog signal and the threshold voltage, and the threshold voltage is set so as to perform short-circuit protection with a lower threshold voltage as the element temperature becomes higher. You only have to set it. In this case, the temperature sensing diode 10 and the temperature analog output circuit 11 may be omitted.

Embodiment 4 FIG.
FIG. 4 is a circuit block diagram showing the drive circuit 104 for the semiconductor switching element according to the fourth embodiment of the present invention. The drive circuit 104 includes an AD conversion circuit 14, an arithmetic circuit 15, a comparator 16, a monitor output unit 17, and an allowable temperature difference setting circuit 18, and does not have the dead time adjustment circuit 13. Except for this point, the drive circuit 104 has the same circuit configuration as the drive circuit 101. The drive circuit 104 and the semiconductor switching element 1 constitute a semiconductor device 154 according to the fourth embodiment. The drive circuit 104 includes a signal circuit 113 configured by the input circuit 3, the output control circuit 4, and the drive circuit 5, as in the third embodiment.

  The AD conversion circuit 14 AD converts 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 arithmetic circuit 15 calculates the difference between the element temperature of the semiconductor switching element 1 and the temperature of the drive circuit 104 which are AD converted by the AD conversion circuit 14 and expressed as a digital value, 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 becomes smaller than the voltage input to the positive input terminal.

  The AD conversion circuit 14 and the arithmetic circuit 15 are connected to a monitor output unit 17 outside the drive circuit 104. The monitor output unit 17 displays the element temperature, the temperature of the drive circuit 104, and the temperature difference ΔT, and the information can be visually recognized by the user. 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.

  The drive circuit 104 includes a 3-input AND circuit 40. The AND circuit 40 receives the output signal from the comparator 16, the output signal from the overheat protection circuit 7, and the output signal from the output control circuit 4. Only when these three input signals are present, an overheat protection signal is transmitted to the error control circuit 6. Thus, the error signal from the comparator 16 can be masked in a state where the temperature is not high, or in a state where the input circuit 3 has no input signal and the drive circuit 104 is not operating.

  By calculating the temperature difference ΔT, the comparator 16 can determine whether or not the cooling structure of the semiconductor device 154 is as designed with respect to the element temperature of the semiconductor switching element 1. When the temperature difference ΔT is smaller than a predetermined value, the temperature of the drive circuit 104 is too close to the element temperature of the semiconductor switching element 1. Normally, the temperature of the drive circuit 104 is usually lower than the element temperature by a certain degree or more, so when the temperature difference ΔT is smaller than a predetermined value, the cooling structure is not expected to exhibit the designed cooling performance. Is done. In this case, a 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.

  According to the fourth embodiment described above, it is possible to detect variation in the cooling structure and acquire information for protecting the semiconductor device 154.

Embodiment 5. FIG.
FIG. 5 is a circuit block diagram showing a drive circuit for a semiconductor switching element according to the fifth embodiment of the present invention. The drive circuit 105 includes an identification circuit 19 instead of the comparator 16. Further, the monitor 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 configuration as the drive circuit 104. The drive circuit 105 and the semiconductor switching element 1 constitute a semiconductor device 155 according to the fifth embodiment. Note that the drive circuit 105 includes a signal circuit 113 including the input circuit 3, the output control circuit 4, and the drive circuit 5, as in the third embodiment.

  As in the fourth embodiment, the AD converter circuit 14 converts the temperatures of the semiconductor switching element 1 and the drive circuit 105 into digital values, and the arithmetic circuit 15 calculates the temperature difference ΔT. The temperature difference ΔT calculated by the calculation circuit 15 is input to the identification circuit 19.

The identification circuit 19 compares the value of the temperature difference ΔT with a comparison value stored inside. Specifically, to set the first comparison value T _A and the second comparison value T _B at the time of designing of the cooling structure of the semiconductor device 155, the normal range of the temperature difference [Delta] T on the cooling structural design T _A ≦ [Delta] T ≦ T _B And 0 _<case of the T A _{<T B,} can determine the abnormality occurrence location as follows. In the fifth embodiment, the specific 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 switching element 1.

(Abnormality 1) When ΔT <0, abnormalities such as abnormal heat generation of the drive circuit 105 or a short circuit in the output stage of the drive circuit 5 are suspected.
(Error 2) when it is 0 ≦ ΔT _{<T A,} the abnormality is suspected of cooling structure of the semiconductor device 155.
(Abnormality 3) When T _B <ΔT, abnormalities such as abnormal heat generation of the semiconductor switching element 1 or a short circuit between the drain and source of the semiconductor switching element 1 are suspected.

When an IGBT or a bipolar transistor is used as the semiconductor switching element 1, a short circuit between the collector and the emitter is suspected when T _B <ΔT.

  The identification circuit 19 outputs a plurality of types of error signals for determining an abnormality occurrence position set in advance according to the temperature difference ΔT. This error signal is input to the error control circuit 6 via the AND circuit 40.

  The identification circuit 19 is designed to output at least three different error signals. These three types of error signals are assigned to the above-described abnormality 1 to abnormality 3, respectively. In this embodiment, the identification circuit 19 outputs three types of error signals having different duty ratios, and the error signals are input to the error control circuit 6, and the error control circuit 6 receives the duty signal at the error signal terminal 53. Assume that three types of error signals with different ratios are output. Accordingly, the user can identify abnormality 1 to abnormality 3 through the error signal terminal 53.

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

Embodiment 6 FIG.
FIG. 6 is a circuit block diagram showing a semiconductor switching element drive circuit 103 and a semiconductor device 156 including the same according to the sixth embodiment of the present invention. The semiconductor device 156 is different from the third embodiment in that the semiconductor device 156 includes the semiconductor switching element 20. The drive circuit 103 that drives the semiconductor switching element 20 is the same as that in the third embodiment.

  The semiconductor switching element 20 is a switching element using SiC (silicon carbide) as a semiconductor material. A SiC device using SiC as a semiconductor material is excellent in electrical characteristics and thermal characteristics.

  In the sixth embodiment, the semiconductor switching element 20 is connected to the drive circuit 103, but the present invention is not limited to this. A semiconductor device in which the semiconductor switching element 20 is connected to any of the drive circuits 101, 102, and 104 to 105 may be provided.

  Various semiconductor materials and element structures of the semiconductor switching element 1 can be applied. For example, an IGBT formed of silicon or a power MOSFET formed of silicon may be used.

Two or more technical features of the drive circuits 101 to 105 and the semiconductor devices 151 to 156 according to the first to sixth embodiments described above may be arbitrarily combined. Specifically, two or more configurations may be arbitrarily selected from the group consisting of the following configurations A to F, and the selected two or more configurations may be provided in one drive circuit or one semiconductor device.
(Configuration A) Dead time adjusting circuit 13 according to the first embodiment
(Configuration B) Driver Circuit 25 According to Second Embodiment
(Configuration C) Short-Circuit Protection Circuit 33 and Voltage Dividing Circuit 34 According to Embodiment 3
(Configuration D) AD conversion circuit 14, arithmetic circuit 15, comparator 16, monitor output unit 17, allowable temperature difference setting circuit 18, and AND circuit 40 according to the fourth embodiment
(Configuration E) Identification Circuit 19 According to Embodiment 5
(Configuration F) Semiconductor switching element 20 according to the sixth embodiment

1, 20 Semiconductor switching 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 sense diode 11, 12 Temperature analog output circuit, 13 Dead time adjustment circuit, 14 AD conversion circuit, 15 Arithmetic circuit, 16 Comparator, 17 Monitor output unit, 18 Allowable temperature difference setting circuit, 19 Identification circuit, 33 Short circuit protection circuit, 34 minutes Pressure 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 (3)

An input terminal to which an input signal is input;
An output terminal connected to the control terminal of the semiconductor switching element;
A signal circuit unit that generates a drive signal from the input signal and supplies the drive signal to the output terminal;
First temperature detection means for outputting a first temperature detection signal having a correlation with the temperature of the signal circuit section, and second temperature detection means for receiving a second temperature detection signal from an element temperature sensor element for detecting the temperature of the semiconductor switching element Temperature sensing means including both,
Short-circuit protection terminal;
A short circuit protection circuit that transmits a stop signal to the signal circuit unit when the voltage input to the short circuit protection terminal reaches a threshold value, and sets the threshold value based on both the first temperature detection signal and the second temperature detection signal. When,
A drive circuit for a semiconductor switching element. An input terminal to which an input signal is input;
An output terminal connected to the control terminal of the semiconductor switching element;
A signal circuit unit that generates a drive signal from the input signal and supplies the drive signal to the output terminal;
A temperature detection circuit that outputs a first temperature detection signal having a correlation with the temperature of the signal circuit unit;
A temperature detection terminal for receiving a second temperature detection signal from a temperature sensor element of the semiconductor switching element;
An error signal generation circuit that outputs an error signal based on a difference between the temperature indicated by the first temperature detection signal and the temperature indicated by the second temperature detection signal;
A drive circuit for a semiconductor switching element.   3. The semiconductor switching element driving circuit according to claim 2, wherein the error signal generation circuit switches a plurality of different error signals according to a value of the temperature difference.

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