An IGBT overcurrent protection circuit, an intelligent power module and a driving device

Abstract

The application discloses an IGBT overcurrent protection circuit, an intelligent power module and a driving device. The IGBT overcurrent protection circuit comprises a sampling circuit, an overcurrent detection circuit and a control circuit. The sampling circuit is connected with the IGBT and is used for collecting working state information of the IGBT. The input end of the overcurrent detection circuit is connected with the sampling circuit. The overcurrent detection circuit performs overcurrent detection on the IGBT according to the working state information, and outputs a corresponding overcurrent signal when overcurrent occurs in the IGBT. The input end of a timing judgment circuit is connected with the output end of the overcurrent detection circuit. The timing judgment circuit is used for judging an overcurrent type according to the pulse width of the corresponding overcurrent signal. The control circuit is connected with the timing judgment circuit and the overcurrent detection circuit. The control circuit is used for performing corresponding overcurrent protection on the IGBT according to the overcurrent type. The application can provide corresponding fault protection according to different fault types, thereby effectively protecting the IGBT and improving the reliability of the driver.

Description

Technical Field

[0001] This invention belongs to the field of IGBT overcurrent protection, and particularly relates to an IGBT overcurrent protection circuit, an intelligent power module, and a driving device. Background Technology

[0002] IGBTs, due to their advantages in frequency, current, and voltage operating range, occupy an important position in power conversion and automatic control fields, becoming a core component of power conversion products. However, in industrial applications, the complex operating conditions and high performance requirements of IGBTs often lead to IGBT failures, with IGBT overcurrent being a key concern. Therefore, overcurrent protection is a crucial technology in IGBT applications. Overcurrent protection circuits not only affect the operating performance and safety of the IGBT itself but also impact the performance and safety of the entire system.

[0003] Existing overcurrent detection methods for IGBTs include traditional Uce desaturation detection, current sensor detection, and di / dt detection. However, these methods cannot differentiate between different types of IGBT faults, hindering effective IGBT protection. For example, brief switching current spikes during IGBT turn-on and current overshoots during motor operation can trigger alarms. When an IGBT experiences a low-level overload, its protection circuit does not need a high response speed. When a short-circuit current occurs, immediate action is required. However, to avoid excessive di / dt of the turn-off current leading to overvoltage, which could cause IGBT lockout failure and damage, the gate voltage is typically reduced. This method, however, cannot prevent frequent short-circuit protection, which can lead to heat buildup and IGBT damage.

[0004] In view of this, the present invention is proposed. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to overcome the shortcomings of the prior art and provide an IGBT overcurrent protection circuit, an intelligent power module and a driving device. By utilizing the change of Uce under different overcurrent conditions of the IGBT, the operating state of the IGBT is dynamically reflected, and corresponding fault protection is provided according to different fault types, thereby effectively protecting the IGBT and improving the reliability of the driver.

[0006] To solve the above-mentioned technical problems, the present invention provides an IGBT overcurrent protection circuit, comprising:

[0007] The sampling circuit is connected to the IGBT and is used to collect the operating status information of the IGBT.

[0008] The overcurrent detection circuit has its input terminal connected to the sampling circuit. The overcurrent detection circuit performs overcurrent detection on the IGBT based on the operating status information, and outputs the corresponding overcurrent signal when the IGBT experiences overcurrent.

[0009] The timing judgment circuit has its input terminal connected to the output terminal of the overcurrent detection circuit. The timing judgment circuit is used to determine the overcurrent type based on the pulse width of the corresponding overcurrent signal.

[0010] The control circuit is connected to both the timing judgment circuit and the overcurrent detection circuit. The control circuit is used to provide appropriate overcurrent protection for the IGBT according to the type of overcurrent.

[0011] Alternatively, the operating status information may include the Uce voltage.

[0012] Further optionally, the overcurrent detection circuit includes:

[0013] The first comparator is used to compare the Uce voltage of the IGBT with the first preset voltage to determine whether the IGBT is overloaded, and output an overload signal when an overload is determined.

[0014] The second comparator is used to compare the Uce voltage of the IGBT with the second preset voltage to determine whether the IGBT is short-circuited, and outputs a short-circuit signal when a short circuit is determined.

[0015] The second preset voltage is greater than the first preset voltage.

[0016] Alternatively, the input terminal of the timing judgment circuit is connected to the output terminal of both the first comparator and the second comparator;

[0017] The timing judgment circuit is used to determine whether the pulse width of the overload signal is greater than the set threshold; if so, it is determined to be a continuous output overload and outputs a soft shutdown signal; if not, it is determined to be an on-peak overload.

[0018] The timing judgment circuit is also used to determine whether the pulse width of the short-circuit signal is greater than the set threshold; if so, it is determined to be a continuous large current and outputs a frequency reduction signal and a soft shutdown signal; if not, it is determined to be a peak large current.

[0019] Optionally, the overcurrent detection circuit further includes a latch, the input of which is connected to the output of the first comparator and the output of the second comparator, respectively.

[0020] The latch outputs a reduced gate voltage signal when the first comparator outputs an overload signal and the second comparator outputs a short-circuit signal, and stops outputting the reduced gate voltage signal after the overload signal is reset.

[0021] Further optionally, the control circuit also includes:

[0022] The drive control circuit generates drive signals, which are used to control the IGBT's on / off state.

[0023] The frequency reduction circuit is connected to the timing judgment circuit. The frequency reduction circuit responds to the frequency reduction signal and blocks the drive signal of the drive control circuit to reduce the operating frequency of the IGBT.

[0024] Further optionally, the frequency reduction circuit includes a first resistive element, a second resistive element, a third resistive element, a first transistor, a second transistor, and a capacitive element; wherein,

[0025] The base of the first transistor is connected to the base of the second transistor, the emitter of the first transistor is connected to the emitter of the second transistor, the collector of the first transistor is connected to the power supply, and the collector of the second transistor is grounded through a third resistive element.

[0026] A capacitive element, one end of which is grounded and the other end is connected to the emitter of the second transistor;

[0027] One end of the first resistive element is the input terminal of the frequency reduction circuit, and the output terminal of the first resistive element is connected to the base of both the first transistor and the second transistor.

[0028] One end of the second resistive element is connected to the base of both the first and second transistors, and the other end of the second resistive element is connected to the emitter of both the first and second transistors.

[0029] Further optionally, the control circuit also includes:

[0030] The gate voltage reduction circuit responds to the gate voltage reduction signal to provide gate voltage reduction protection for the IGBT.

[0031] The present invention also provides an intelligent power module, which includes an overcurrent protection circuit of any of the above-described technical solutions.

[0032] The present invention also provides a driving device, which includes an overcurrent protection circuit of any of the above-described technical solutions, or includes an intelligent power module as described above.

[0033] By adopting the above technical solution, the present invention has the following beneficial effects compared with the prior art:

[0034] By utilizing the changes in Uce under different overcurrent conditions of the IGBT, the operating state of the IGBT is dynamically reflected, and corresponding fault protection is provided according to different fault types, thereby effectively protecting the IGBT and improving the reliability of the driver. Furthermore, a frequency reduction circuit is added to the short-circuit protection circuit to avoid the problem of the IGBT continuing to operate at the original frequency after a fault, frequently triggering short-circuit protection, and causing heat accumulation that could damage the IGBT, thus improving the safety of the IGBT.

[0035] The specific embodiments of the present invention will now be described in further detail with reference to the accompanying drawings. Attached Figure Description

[0036] The accompanying drawings, as part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments and descriptions of the invention are used to explain the invention, but do not constitute an undue limitation of the invention. Obviously, the drawings described below are merely some embodiments, and those skilled in the art can obtain other drawings based on these drawings without creative effort. In the drawings:

[0037] Figure 1 This is a traditional IGBT overcurrent protection circuit.

[0038] Figure 2 An exemplary schematic diagram of an IGBT overcurrent protection circuit according to an embodiment of the present invention is shown.

[0039] Figure 3 A schematic diagram of a frequency reduction circuit according to an embodiment of the present invention is shown as an example.

[0040] Figure 4 An exemplary schematic diagram of the overcurrent processing logic of an IGBT overcurrent protection circuit according to an embodiment of the present invention is shown.

[0041] Among them: 1-overcurrent detection circuit, 2-timing judgment circuit, 3-drive control circuit, 4-frequency reduction circuit, 5-gate voltage reduction circuit.

[0042] It should be noted that these accompanying drawings and textual descriptions are not intended to limit the scope of the invention in any way, but rather to illustrate the concept of the invention to those skilled in the art by referring to specific embodiments. Detailed Implementation

[0043] In the description of this invention, it should be noted that the terms "inner" and "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limiting this invention.

[0044] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," "contact," and "communication" should be interpreted broadly. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to mechanical connections or electrical connections; they can refer to direct connections or indirect connections through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0045] Combination Figure 1 Traditional IGBT overcurrent protection circuits employ direct soft turn-off or gate voltage reduction to protect the IGBT. Direct soft turn-off is only suitable for small overcurrent values. In the event of a short circuit, if the IGBT is directly soft-turned off, the excessive di / dt of the turn-off current can create an overvoltage, leading to ineffective IGBT latch-up and damage. Gate voltage reduction avoids this issue, but it cannot prevent frequent short-circuit protection from causing heat buildup that can damage the IGBT. Therefore, this embodiment provides an IGBT overcurrent protection circuit.

[0046] The following is in conjunction with the appendix Figure 2-4 The IGBT overcurrent protection circuit of this embodiment will be described.

[0047] Reference Figure 2 The IGBT overcurrent protection circuit of this embodiment includes a sampling circuit, an overcurrent detection circuit 1, a timing judgment circuit 2, and a control circuit, wherein:

[0048] The sampling circuit is connected to the IGBT and is used to collect the operating status information of the IGBT.

[0049] The operating status information includes IGBT current information such as di / dt turn-off current, and voltage information such as Uce voltage.

[0050] Overcurrent detection circuit 1, the input terminal of overcurrent detection circuit 1 is connected to sampling circuit, overcurrent detection circuit 1 performs overcurrent detection on IGBT according to working status information, and outputs corresponding overcurrent signal when IGBT has overcurrent;

[0051] Overcurrent detection circuit 1 distinguishes different overcurrent conditions and takes different overcurrent measures accordingly.

[0052] Further optional, refer to Figure 2 The overcurrent detection circuit 1 includes:

[0053] The first comparator U1 is used to compare the Uce voltage of the IGBT with the first preset voltage Vref1 to determine whether the IGBT is overloaded, and output an overload signal when an overload is determined.

[0054] The second comparator U2 is used to compare the Uce voltage of the IGBT with the second preset voltage Vref2 to determine whether the IGBT is short-circuited, and output a short-circuit signal when a short circuit is determined.

[0055] In this context, the Uce voltage of the IGBT is the voltage between the collector and emitter. The first preset voltage Vref1 is the overload threshold voltage, and the second preset voltage Vref2 is the short-circuit threshold voltage. Therefore, the second preset voltage Vref2 is greater than the first preset voltage Vref1.

[0056] Specifically, when the Uce voltage is greater than Vref1 and less than or equal to Vref2, the IGBT is determined to be overloaded; when the Uce voltage is greater than Vref2, the IGBT is determined to be short-circuited.

[0057] Further optional, refer to Figure 2 The overcurrent detection circuit 1 also includes a latch U3, the input of which is connected to the output of the first comparator U1 and the output of the second comparator U2, respectively.

[0058] Latch U3 outputs a reduced gate voltage signal when the first comparator U1 outputs an overload signal and the second comparator U2 outputs a short circuit signal, and stops outputting the reduced gate voltage signal after the overload signal is reset.

[0059] When the IGBT is short-circuited, the output of latch U3 is high and is no longer affected by the change in the output of comparator U2 due to the reduced gate voltage; and when a false overcurrent occurs or the IGBT is turned off, the output of comparator U1 is low to reset latch U3. The specific truth table is shown in Table 1.

[0060] Wherein, the CLK input signal is the output signal of the second comparator U2, and the R port input is the output signal of the first comparator U1. As can be seen from Table 1, comparator circuits U1 and U2 output a high level, U3 outputs a high level, comparator circuit U1 outputs a low level, and latch U3 is reset.

[0061] Table 1 Truth Table of Latch U3

[0062] CLK R D Q 1 1 1 1 0 1 1 1 0 0 1 0

[0063] Timing judgment circuit 2, the input terminal of timing judgment circuit 2 is connected to the output terminal of overcurrent detection circuit 1, and timing judgment circuit 2 is used to determine the overcurrent type based on the pulse width of the corresponding overcurrent signal;

[0064] The timing detection circuit 2 distinguishes between true and false overcurrents, thereby improving reliability. Specifically, the timing detection circuit 2 can be a trigger.

[0065] Further optional, refer to Figure 2The input terminal of the timing judgment circuit 2 is connected to the output terminal of the first comparator U1 and the output terminal of the second comparator U2.

[0066] The timing judgment circuit 2 is used to determine whether the pulse width of the overload signal is greater than the set threshold t;

[0067] If so, it is determined to be a continuous output overload, and a soft shutdown signal is output;

[0068] If not, it is determined to be peak overload.

[0069] The timing judgment circuit 2 is also used to determine whether the pulse width of the short-circuit signal is greater than the set threshold t;

[0070] If so, it is determined to be a continuous high current, and a frequency reduction signal and a soft shutdown signal are output;

[0071] If not, it is determined to be a peak high current.

[0072] Specifically, refer to Figure 4 Specifically, when the Uce voltage is greater than Vref1 and the pulse width is less than t (generally set to 3-5us): the overcurrent detection circuit U1 outputs an overload signal, but the pulse width of the overload signal does not exceed the set threshold t, so it is determined to be a turn-on spike overload, and therefore the overcurrent signal is not processed.

[0073] When the Uce voltage is greater than Vref1 and the pulse width is greater than t: the overcurrent detection circuit U1 outputs an overload signal, and after a delay of t, the drive control adopts a soft shutdown behavior;

[0074] When the Uce voltage is greater than Vref2 and the pulse width is less than t: the overcurrent detection circuits U1 and U2 both output a high level, and U3 outputs a high level. The drive control adopts the gate voltage reduction protection measure. However, the overcurrent signal does not exceed the set threshold t. After time t, the comparator circuit U1 outputs a low level, resetting the latch U3, thereby releasing the gate voltage reduction protection measure.

[0075] When the Uce voltage is greater than Vref2 and the pulse width is greater than t: the overcurrent detection circuits U1 and U2 output high level, and U3 outputs high level. The drive control adopts the protection measure of reducing the gate voltage. After a delay of t, the drive control adopts the behavior of reducing frequency and soft shutdown.

[0076] The control circuit is connected to both the timing judgment circuit 2 and the overcurrent detection circuit 1. The control circuit is used to provide corresponding overcurrent protection for the IGBT according to the type of overcurrent.

[0077] Further optionally, the control circuit includes:

[0078] Drive control circuit 3 is used to generate drive signals, which are used to drive the IGBT to switch on and off.

[0079] Frequency reduction circuit 4 is connected to timing judgment circuit 2. Frequency reduction circuit 4 responds to the frequency reduction signal and blocks the drive signal of drive control circuit 3 to reduce the operating frequency of IGBT.

[0080] Further optionally, the frequency reduction circuit 4 includes a first resistive element, a second resistive element, a third resistive element, a first transistor Q1, a second transistor Q2, and a capacitive element; specifically, refer to... Figure 3 The first resistive element is a first resistor R1, the second resistive element is a second resistor R2, the third resistive element is a third resistor R3, and the capacitive element is a capacitor C1; wherein,

[0081] The base of the first transistor Q1 is connected to the base of the second transistor Q2, the emitter of the first transistor Q1 is connected to the emitter of the second transistor Q2, the collector of the first transistor Q1 is connected to the power supply, and the collector of the second transistor Q2 is grounded through the third resistor R3.

[0082] Capacitor C1 has one end grounded and the other end connected to the emitter of the second transistor Q2;

[0083] One end of the first resistor R1 is the input terminal of the frequency reduction circuit 4, and the output terminal of the first resistor R1 is connected to the base of both the first transistor Q1 and the second transistor Q2.

[0084] One end of the second resistor R2 is connected to the base of both the first transistor Q1 and the second transistor Q2, and the other end of the second resistor R2 is connected to the emitter of both the first transistor Q1 and the second transistor Q2.

[0085] Specifically, when the circuit initiates soft shutdown, the gate drop signal is high, Q1 turns on to charge C1, and the voltage on C1 causes the drive signal to go low. By selecting a discharge period of approximately 1 second for C1 and R1, the operating frequency of the IGBT can be limited to below 1Hz. After the overcurrent is eliminated, Q2 turns on, and C1 discharges to 0.7V through R1 before the control signal can resume its control over the IGBT.

[0086] Further optional, refer to Figure 2 The control circuit also includes:

[0087] The gate voltage reduction circuit 5 responds to the gate voltage reduction signal to provide gate voltage reduction protection for the IGBT.

[0088] The IGBT overcurrent protection circuit in this embodiment utilizes the changes in Uce under different overcurrent conditions of the IGBT to dynamically reflect the fault type of the IGBT and provide corresponding fault protection according to different fault types, thereby effectively protecting the IGBT and improving the reliability of the driver.

[0089] The present invention also provides an intelligent power module, which includes an overcurrent protection circuit of any of the above-described technical solutions.

[0090] The present invention also provides a driving device, which includes an overcurrent protection circuit of any of the above-described technical solutions, or includes an intelligent power module as described above.

[0091] The device embodiments described above are merely illustrative. The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the modules can be selected to achieve the purpose of this embodiment according to actual needs. Those skilled in the art can understand and implement this without any creative effort.

[0092] Through the above description of the embodiments, those skilled in the art can clearly understand that each embodiment can be implemented by means of software plus necessary general-purpose hardware platforms, and of course, it can also be implemented by hardware. Based on this understanding, the above technical solutions, in essence or the part that contributes to the prior art, can be embodied in the form of a software product. This computer software product can be stored in a computer-readable storage medium, such as ROM / RAM, magnetic disk, optical disk, etc., and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute the methods described in the various embodiments or some parts of the embodiments.

[0093] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-described technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. An IGBT overcurrent protection circuit, characterized in that, include: A sampling circuit, connected to the IGBT, is used to collect the operating status information of the IGBT; An overcurrent detection circuit is provided, the input of which is connected to the sampling circuit. The overcurrent detection circuit is used to detect overcurrent in the IGBT based on the operating status information, and outputs a corresponding overcurrent signal when an overcurrent occurs in the IGBT. A timing judgment circuit is provided, the input terminal of which is connected to the output terminal of the overcurrent detection circuit. The timing judgment circuit is used to determine the overcurrent type based on the pulse width of the corresponding overcurrent signal. The control circuit is connected to both the timing judgment circuit and the overcurrent detection circuit. The control circuit is used to provide corresponding overcurrent protection for the IGBT according to the overcurrent type. The overcurrent detection circuit includes: The first comparator is used to compare the Uce voltage of the IGBT with a first preset voltage to determine whether the IGBT is overloaded, and output an overload signal when an overload is determined. The second comparator is used to compare the Uce voltage of the IGBT with a second preset voltage to determine whether the IGBT is short-circuited, and output a short-circuit signal when a short circuit is determined. Wherein, the second preset voltage is greater than the first preset voltage; The input terminal of the timing judgment circuit is connected to the output terminal of both the first comparator and the output terminal of the second comparator; The timing judgment circuit is used to determine whether the pulse width of the overload signal is greater than a set threshold; if so, it determines that it is a continuous output overload and outputs a soft shutdown signal; if not, it determines that it is an on-peak overload. The timing judgment circuit is also used to determine whether the pulse width of the short-circuit signal is greater than the set threshold; if so, it is determined to be a continuous large current and outputs a frequency reduction signal and the soft shutdown signal; if not, it is determined to be a peak large current.

2. The overcurrent protection circuit as described in claim 1, characterized in that, The operating status information includes the Uce voltage.

3. The overcurrent protection circuit as described in claim 2, characterized in that, The overcurrent detection circuit also includes a latch, the input of which is connected to the output of the first comparator and the output of the second comparator, respectively. The latch outputs a reduced gate voltage signal when the first comparator outputs the overload signal and the second comparator outputs the short-circuit signal, and stops outputting the reduced gate voltage signal after the overload signal is reset.

4. The overcurrent protection circuit as described in claim 3, characterized in that, The control circuit also includes: A drive control circuit is provided, which generates a drive signal to drive the IGBT to switch on and off. A frequency reduction circuit is connected to the timing judgment circuit. The frequency reduction circuit responds to the frequency reduction signal and blocks the drive signal of the drive control circuit to reduce the operating frequency of the IGBT.

5. The overcurrent protection circuit as described in claim 4, characterized in that, The frequency reduction circuit includes a first resistive element, a second resistive element, a third resistive element, a first transistor, a second transistor, and a capacitive element; wherein, The base of the first transistor is connected to the base of the second transistor, the emitter of the first transistor is connected to the emitter of the second transistor, the collector of the first transistor is connected to the power supply, and the collector of the second transistor is grounded through a third resistive element. The capacitive element has one end grounded and the other end connected to the emitter of the second transistor; One end of the first resistive element is the input terminal of the frequency reduction circuit, and the output terminal of the first resistive element is connected to the base of both the first transistor and the second transistor. One end of the second resistive element is connected to the base of both the first transistor and the second transistor, and the other end of the second resistive element is connected to the emitter of both the first transistor and the second transistor.

6. The overcurrent protection circuit as described in any one of claims 3-5, characterized in that, The control circuit also includes: A gate voltage reduction circuit, which responds to the gate voltage reduction signal to perform gate voltage reduction protection on the IGBT.

7. A smart power module, characterized in that, Includes the overcurrent protection circuit described in any one of claims 1-6.

8. A driving device, characterized in that, It includes the overcurrent protection circuit as described in any one of claims 1-6, or the intelligent power module as described in claim 7.

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