CN115811025A - Adaptive soft-off current overcurrent protection circuit, device and safety chip - Google Patents
Adaptive soft-off current overcurrent protection circuit, device and safety chip Download PDFInfo
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Abstract
The application discloses soft turn-off current's of self-adaptation overcurrent protection circuit, device and safety chip includes: the voltage comparison unit is used for inputting a sampling signal and a reference voltage of the controlled module and outputting an overcurrent protection signal under the enabling control of the pulse width modulation signal; the soft turn-off signal generating unit is connected with the voltage comparing unit and is used for latching an overcurrent protection signal output when the pulse width modulation signal is at a high level when the pulse width modulation signal is at a low level and outputting a soft turn-off enabling signal; and the soft turn-off control unit is connected with the soft turn-off signal generation unit and is used for generating a driving control signal of the controlled module according to the soft turn-off enabling signal and the sampling signal of the controlled module. The soft turn-off time duration is long when the overcurrent is serious; when the overcurrent is small, the soft turn-off time duration is short, so that the controlled module is protected.
Description
Technical Field
The application relates to the technical field of electronic circuits, in particular to an overcurrent protection circuit, an overcurrent protection device and a safety chip of self-adaptive soft turn-off current.
Background
The functional safety chip has wide application prospect in new energy automobile and common automobile intellectualization, and many motor drives related to life safety on the automobile need functional safety guarantee. Compared with a common vehicle-scale chip, the functional safety chip has a stricter requirement on the protection of an Insulated Gate Bipolar Transistor (IGBT) or a Semiconductor Integrated Circuit (SIC).
However, in some existing driving product schemes, generally, a fixed Soft Shutdown (SSD) current is used to turn off the IGBT, and generally, after overcurrent protection (OCP) occurs, even if the IGBT is turned off, the normal working period of the IGBT is affected, which may cause the system to fail to work normally.
When the IGBT is in overcurrent, the IGBT is turned off by a fixed SSD current, and when the overcurrent degree is large or small, the SSD current is the same, and the overcurrent is likely to be large, the IGBT is turned off too fast, so that excessive dv/dt (differential of voltage variation relative to time) is generated at the collector of the IGBT, and the IGBT is easy to damage; and if the closing is too slow, when the overcurrent is small, the closing time is too long, and the system response is greatly influenced.
Disclosure of Invention
The IGBT protection circuit aims to solve the problems that in the prior art, a fixed SSD current is used for closing an IGBT, and if the fixed SSD current is closed too fast, overlarge dv/dt is generated on a collector of the IGBT, so that the IGBT is easy to damage; and if the closing is too slow, the closing time is too long, and the technical problem of great influence on the system response is solved.
One of the objectives of the present application is to provide an adaptive soft-off current over-current protection device.
It is an object of the present application to provide a security chip.
To achieve one of the objectives of the above application, an embodiment of the present application provides an adaptive soft-off current over-current protection circuit, including:
the voltage comparison unit is used for inputting a reference voltage and a sampling signal of a controlled module, and the voltage comparison unit compares the reference voltage with the sampling signal of the controlled module to obtain a comparison result; under the enabling control of the pulse width modulation signal, the voltage comparison unit outputs an overcurrent protection signal according to the comparison result;
the soft turn-off signal generating unit is connected with the voltage comparing unit and is used for latching an overcurrent protection signal when the pulse width modulation signal is at a low level; the voltage comparison unit outputs the overcurrent protection signal when the overcurrent protection signal is the high level of the last pulse width modulation signal; the soft turn-off signal generating unit outputs a soft turn-off enabling signal when the pulse width modulation signal is at a low level;
and the soft turn-off control unit is connected with the soft turn-off signal generation unit and generates a driving control signal of the controlled module according to the soft turn-off enabling signal and the sampling signal of the controlled module.
As a further improvement of an embodiment of the present application, the soft turn-off signal generating unit includes a first RS trigger, a delay unit, an and gate unit, a second RS trigger, and a soft turn-off time control unit;
the S input end of the first RS trigger is connected with the voltage comparison unit, and the first RS trigger is used for receiving the overcurrent protection signal; the R input end of the first RS trigger is connected with an inverse signal of the pulse width modulation signal;
the delay unit is connected with the first RS trigger and the AND gate unit, and is used for delaying the output signal of the first RS trigger to obtain an overcurrent protection pulse width modulation delay signal; the AND gate unit performs AND logic judgment on the overcurrent protection pulse width modulation delay signal and an inverse signal of the pulse width modulation signal to obtain a logic judgment result; the AND gate unit inputs the logic judgment result to an S input end of the second RS trigger;
the R input end of the second RS trigger is connected with the soft turn-off time control unit; the second RS trigger outputs a soft off enable signal.
As a further improvement of an embodiment of the present application, the soft-off time control unit includes a current source, a soft-off bias current generation unit, and a first resistor;
the input end of the current source is connected with a power supply, the output end of the current source is connected with the first end of the soft turn-off bias current generating unit, and the second end of the soft turn-off bias current generating unit is connected to the ground GND through the first resistor;
the first end of the soft off bias current generating unit is connected to the R input end of the second RS trigger.
As a further improvement of an embodiment of the present application, the soft-off bias current generating unit includes a first operational amplifier and a first MOS transistor;
the output end of the current source is connected with the drain electrode of the first MOS tube, and the source electrode of the first MOS tube is connected to the ground GND through the first resistor; the positive input end of the first operational amplifier is connected with the sampling signal of the controlled module, the reverse input end of the first operational amplifier is connected with the source electrode of the first MOS tube, and the output end of the first operational amplifier is connected with the grid electrode of the first MOS tube.
As a further improvement of the embodiment of the present application, the soft-off control unit includes a second operational amplifier, a second resistor, a third resistor, a second MOS transistor, and a third MOS transistor;
the positive input end of the second operational amplifier is connected to the drain electrode of the first MOS transistor and one end of the second resistor, the other end of the second resistor is connected to the ground GND, the reverse input end of the second operational amplifier is connected to the source electrode of the second MOS transistor, and the enable end of the second operational amplifier is connected to the output end of the second RS trigger; the output end of the second operational amplifier is connected to the grid electrode of the second MOS tube and the grid electrode of the third MOS tube;
the source electrode of the second MOS tube is connected to the ground GND through the third resistor; the source electrode of the third MOS tube is connected to the ground GND;
the drain electrode of the second MOS tube is connected to the drain electrode of the third MOS tube, and the drain electrode of the third MOS tube is connected to the control end of the controlled module.
As a further improvement of an embodiment of the present application, a current on the second MOS transistor is represented as follows:
wherein, lnld 0 is the current of the second MOS transistor, SSD _ VBIAS is the voltage formed on the second resistor by the current, which is obtained by subtracting the soft-off bias current Ibias1 generated by the soft-off bias current generating unit from the current Ibias0 generated by the current source, and R3 is the resistance value of the third resistor.
Further, the current on the third MOS transistor is represented as follows:
the Inld1 is the current of the third MOS tube, K is a multiple of the chip size of the third MOS tube relative to the chip size of the second MOS tube, and the chip size refers to the width-to-length ratio of a chip; ibias0 is the current generated by the current source, OC _ SENSE is the sampling signal of the controlled module, R1 is the resistance value of the first resistor, R2 is the resistance value of the second resistor, and R3 is the resistance value of the third resistor.
MOS, is an abbreviation for MOSFET. A MOSFET Metal-Oxide semiconductor field Effect Transistor (MOSFET) is a Metal-Oxide-semiconductor field-Effect Transistor (MOSFET).
In order to achieve one of the above objectives, an embodiment of the present application provides an adaptive soft-off current overcurrent protection device, including the adaptive soft-off current overcurrent protection circuit according to any one of the above technical solutions.
In order to achieve one of the above objectives, an embodiment of the present application provides a security chip, including the adaptive soft-off current overcurrent protection circuit according to any one of the above technical solutions.
One of the above technical solutions has the following advantages or beneficial effects:
compared with the prior art, the overcurrent protection circuit of the self-adaptive soft turn-off current generates an overcurrent protection signal through the voltage comparison unit, and the state of overcurrent protection is realized when the PWM signal is turned down, namely the system really closes the IGBT, through the first RS trigger, the delay unit and the AND gate unit, so that the influence of the overcurrent protection on the state of the system is avoided.
According to the soft turn-off time control method and device, the soft turn-off time can be adjusted according to the voltage SSD _ VBIAS formed by the current generated by subtracting the soft turn-off bias current Ibias1 generated by the soft turn-off bias current generation unit from the current Ibias0 generated by the current source on the second resistor through the soft turn-off time control unit composed of the current source, the soft turn-off bias current generation unit and the first resistor.
The SSD current (namely the current Inld1 of the third MOS tube) generated by the soft turn-off control unit is related to a sampling signal OC _ SENSE of a controlled module, so that when overcurrent is large, OC _ SENSE is large, the current Inld1 on the third MOS tube is small, and the IGBT closing speed is slow, so that the IGBT is protected from overvoltage impact of VCE (voltage from a collector electrode C to an emitter electrode E of the IGBT). When the overcurrent of the IGBT is small, OC _ SENSE is small, inld1 is large, and the closing speed of the IGBT is high, so that the response speed of the system is improved when the overcurrent is not serious.
Drawings
The drawings described herein are for illustration purposes only and are not intended to limit the scope of the present disclosure in any way. In addition, the shapes, the proportional sizes, and the like of the respective members in the drawings are merely schematic for assisting understanding of the present application, and do not specifically limit the shapes, the proportional sizes, and the like of the respective members in the present application. The application can be carried out by a person skilled in the art, in the light of the teaching of the application, selecting from a variety of possible shapes and proportional dimensions according to the specific case. In the drawings:
fig. 1 is a schematic structural diagram of an adaptive soft-off current overcurrent protection circuit according to an embodiment of the present application;
fig. 2 is a waveform diagram of the adaptive soft turn-off current overcurrent protection circuit in turn-off for IGBT large current application according to an embodiment of the present application;
reference numerals are as follows: the circuit comprises a 1-voltage comparison unit, a 2-soft turn-off signal generation unit, a 3-soft turn-off control unit, a 4-sampling unit, a 201-first RS trigger, a 202-delay unit, a 203-AND gate unit, a 204-second RS trigger, a 205-current source, a 206-soft turn-off bias current generation unit, a 261-first operational amplifier, a 262-first MOS tube, a 301-second operational amplifier, a 302-second MOS tube, a 303-third MOS tube, a 11-first resistor, a 12-second resistor, a 13-third resistor and a 14-fourth resistor.
Detailed Description
In order to make those skilled in the art better understand the technical solutions in the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application, and it is obvious that the described embodiments are only a part of the embodiments of the present application, and not all the embodiments. All other embodiments obtained by a person of ordinary skill in the art based on the embodiments in the present application without making creative efforts shall fall within the protection scope of the present application.
It is to be noted that the term "comprises," "comprising," or any other variation thereof is intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Furthermore, the terms "first," "second," "third," and the like are used for descriptive purposes only and are not to be construed as indicating or implying relative importance.
The functional safety chip is a micro control unit and is widely applied to intellectualization of new energy automobiles and common automobiles. The automobile safety chip is also known as a vehicle gauge safety chip, namely the vehicle gauge safety chip, and is a specification standard suitable for automobile electronic components. Compared with other industrial electronic elements, the automotive-gauge-grade electronic element has the advantages of low requirement on external working environment, long service life, and high reliability and consistency. The vehicle-scale safety chip is a chip with safety performance produced according to the specification standard of the automobile electronic component.
Compared with the common vehicle-scale chip, the functional safety chip has stricter requirements on the protection of the IGBT or the SIC, a turn-off mode is called step turn-off in the process of turning off the IGBT or the SIC, the grid voltage of the IGBT or the SIC can be controlled by detecting the collector voltage of the IGBT or the Drain terminal voltage of the SIC, and the purpose of reducing dv/dt is achieved, so that the IGBT or the SIC is protected better.
Some existing driving product schemes generally use a fixed Soft Shutdown (SSD) current to turn off the IGBT, and generally after OCP occurs, even if the IGBT is turned off, the normal operating period of the IGBT is affected, which may cause the system to fail to operate normally. Under the condition that the IGBT is in overcurrent, the IGBT is turned off by using fixed SSD current, when the overcurrent degree is large or small, the SSD current is the same, and the overcurrent is likely to be caused to be too fast, so that overlarge dv/dt is generated on a collector of the IGBT, the IGBT is easy to damage, and if the turn-off is too slow, the turn-off time is too long when the overcurrent is small, and the system response is greatly influenced.
How to adapt to the over-current protection circuit of the soft turn-off current to protect the controlled module is one of the purposes of the application.
An embodiment of the present application provides an overcurrent protection circuit for adaptive soft off current, which can be disposed in any kind of safety chip or overcurrent protection device for adaptive soft off current, or independently exist in other application scenarios, and is used for performing overcurrent protection on a controlled module.
As shown in fig. 1, the adaptive soft-off current overcurrent protection circuit includes:
the voltage comparison unit 1 is used for inputting a sampling signal and a reference voltage of a controlled module, the voltage comparison unit 1 compares the voltage of the sampling signal and the reference voltage, and outputs an overcurrent protection signal according to a comparison result under the enabling control of a Pulse Width Modulation (PWM) signal;
the soft shutdown signal generation unit 2 is connected with the voltage comparison unit 1 and used for latching an overcurrent protection signal output by the voltage comparison unit 1 when the pulse width modulation signal is at a high level when the pulse width modulation signal is at a low level, and the soft shutdown signal generation unit 2 outputs a soft shutdown enabling signal when the pulse width modulation signal is at a low level;
and the soft turn-off control unit 3 is connected with the soft turn-off signal generating unit 2 and is used for generating a driving control signal of the controlled module according to the soft turn-off enabling signal and the sampling signal of the controlled module.
The invention solves the problem of overvoltage of the IGBT or the SIC caused by directly closing the power tube in the traditional scheme, and the voltage is closed in a grading way by detecting the VCE voltage of the IGBT, thereby improving the VCE overvoltage of the IGBT under the condition of large current application. The overcurrent protection circuit provided by the embodiment can better protect a controlled module (such as an IGBT).
As shown in fig. 1, optionally, the soft-off signal generating unit 2 includes a first RS flip-flop 201, a delay unit 202, an and gate unit 203, a second RS flip-flop 204, and a soft-off time control unit;
the S input end of the first RS flip-flop 201 is connected to the voltage comparing unit 1, and is configured to receive an overcurrent protection signal; the R input end of the first RS trigger 201 is connected with an inverse signal PWM _ B of the pulse width modulation signal PWM;
the Delay unit 202 is connected to the first RS flip-flop 201 and the and gate unit 203, and configured to Delay an output signal of the first RS flip-flop 201 to obtain an overcurrent protection pulse width modulation Delay signal (see OCP PWM off Delay in fig. 1), and the and gate unit 203 performs and logical judgment on the overcurrent protection pulse width modulation Delay signal and an inverse signal PWM _ B of the pulse width modulation signal, and then inputs the result to an S input end of the second RS flip-flop 204; the R input end of the second RS trigger 204 is connected with the soft turn-off time control unit; the second RS flip-flop 204 outputs a soft off enable signal EN SSD.
The soft-off time control unit includes a current source 205, a soft-off bias current generation unit 206, and a first resistor 11;
the input end of the current source 205 is connected to the power supply, the output end of the current source 205 is connected to the first end of the soft-off bias current generating unit 206, and the second end of the soft-off bias current generating unit 206 is connected to the ground GND through the first resistor 11; a first terminal of the soft-off bias current generating unit 206 is connected to the R input terminal of the second RS flip-flop 204.
Optionally, the soft-off bias current generating unit 206 includes a first operational amplifier 261 and a first MOS transistor 262.
The output end of the current source 205 is connected with the drain of the first MOS transistor 262, and the source of the first MOS transistor 262 is connected with the first resistor 11 and connected to the ground GND; the positive input end of the first operational amplifier 261 is connected to the controlled module sampling signal OC _ SENSE, the negative input end is connected to the source of the first MOS transistor 262, and the output end of the first operational amplifier 261 is connected to the gate of the first MOS transistor 262.
The soft-off control unit 3 comprises a second operational amplifier 301, a second MOS transistor 302, a third MOS transistor 303, a second resistor 12 and a third resistor 13; the positive input end of the second operational amplifier 301 is connected to the drain of the first MOS transistor 262 and one end of the second resistor 12, the other end of the second resistor 12 is connected to the ground GND, the negative input end of the second operational amplifier 301 is connected to the source of the second MOS transistor 302, and the enable end of the second operational amplifier 301 is connected to the output end of the second RS flip-flop 204; the output end of the second operational amplifier 301 is connected to the gate of the second MOS transistor 302 and the gate of the third MOS transistor 303; the source of the second MOS transistor 302 is connected to the ground GND through a third resistor 13; the source of the third MOS transistor 303 is connected to ground GND; the drain of the second MOS transistor 302 is connected to the drain of the third MOS transistor 303, and the drain of the third MOS transistor 303 is connected to the control terminal of the controlled module.
As shown in fig. 1, the IGBT sampling signal is obtained by the sampling unit 4 in the present embodiment. And the sampling resistor Rsense is connected to the source electrode of the IGBT, and the current is converted into a voltage signal to be measured, so that an IGBT sampling signal OC _ SENSE is obtained.
In the adaptive soft turn-off current overcurrent protection circuit provided by this embodiment, when PWM is at a high level, that is, when an IGBT is turned on, the voltage comparison unit 1 compares an IGBT sampling signal OC _ SENSE with a reference voltage VREF signal, if OC _ SENSE is higher than VREF, the voltage comparison unit 1 outputs a high signal, outputs an overcurrent protection signal, AND latches the overcurrent protection signal into the first RS flip-flop 201, AND when the PWM becomes low, the first RS flip-flop 201 is set to zero, AND the delay unit 202 maintains the overcurrent protection signal (that is, the OCP alarm signal) output by the first RS flip-flop 201 for a certain time (for example, 100 ns) to obtain an overcurrent protection pulse width modulation delay signal, AND the overcurrent protection pulse width modulation delay signal is anded with a PWM inverse signal PWM _ B by the AND gate unit 203 (AND) to obtain a pulse signal of about 100ns, so that the second RS flip-flop 204 can latch the OCP alarm signal output by the first RS flip-flop 201 when PWM is at a high level, AND at this time, the second RS flip-flop 204 outputs a high signal (that an EN _ signal), so that the second RS flip-flop 204 turns off the EN signal to enable the SSD 301 to start to operate.
The soft-off bias current generating unit 206 converts the voltage signal of the sampling signal OC _ SENSE of the controlled module into a current signal Ibias1, the current Ibias0 minus the current Ibias1 generated by the current source 205 forms a reference voltage SSD _ VBIAS with information of OC _ SENSE on the second resistor 12, and the reference voltage SSD _ VBIAS is converted into a current on the second MOS transistor 302 (i.e. NLD0 in fig. 1) through the second operational amplifier 301, and the expression is as follows:
wherein, lnld 0 is the current of the second MOS transistor 302, SSD _ VBIAS is the voltage formed on the second resistor 12 by the current, which is the current Ibias0 generated by the current source 205 minus the soft-off bias current Ibias1 generated by the soft-off bias current generating unit 206, and R3 is the resistance of the third resistor 13.
The chip size of the third MOS transistor 303 (i.e., NLD1 in fig. 1) is K times the chip size of the second MOS transistor 302 (i.e., NLD0 in fig. 1), where the chip size refers to the width-to-length ratio of the chip; the current on NLD1 is expressed as follows:
wherein, inld1 is the current of the third MOS tube 303; ibias0 is the current generated by the current source 205; OC _ SENSE is the sampling signal of the controlled module, R1 is the resistance value of the first resistor 11, R2 is the resistance value of the second resistor 12, and R3 is the resistance value of the third resistor 13.
According to the method and the device, the current Inld1 related to the sampling signal OC _ SENSE of the controlled module can be obtained to turn off the IGBT, so that when overcurrent is large, OC _ SENSE is large, inld1 is small, and the IGBT is slow in turn-off speed, so that the IGBT is protected from VCE overvoltage impact. When the overcurrent of the IGBT is small, OC _ SENSE is small, lnld 1 is large, and the turn-off speed of the IGBT is high, so that when the overcurrent is not serious, the response speed of the system is increased, as shown in fig. 2, the overcurrent protection waveform of the IGBT under the adaptive SSD current is shown. In addition, the SSD _ time can be adjusted according to the SSD _ VBIAS voltage, the OC _ SENSE is larger when overcurrent is serious, and the SSD _ time is long in duration. OC _ SENSE is shorter in duration than SSD _ time when the overcurrent is small. The maximum and minimum values of SSD current can be adjusted by setting the magnitude of Ibias 0.
The delay unit 202 in this application includes a delay circuit. It should be noted that a circuit for delaying an electrical signal for a certain period of time is called a delay circuit, and is widely used in the field of circuit design. The delay circuit adopted in the application is the prior art and is not introduced too much.
In other embodiments, the drain of the third MOS transistor 303 is connected to the control terminal of the controlled module (e.g., the G terminal of the IGBT) through a fourth resistor 14 (e.g., the resistor ROL in fig. 1).
Optionally, the drain of the third MOS transistor 303 may also be connected to the control end of the controlled module through a filtering unit formed by combining basic elements such as a resistor, a capacitor, an inductor, and the like, where the filtering unit is a RC or RLC filtering circuit structure, which is not an application point of the present application and is not described too much.
In summary, the overcurrent protection circuit for self-adaptive soft turn-off current provided by the present application generates an overcurrent protection signal through the voltage comparison unit 1, and the state of overcurrent protection is realized through the first RS flip-flop 201, the delay unit 202 and the and gate unit 203, and the PWM signal is turned down, that is, the system really needs to turn off the IGBT to function, so as to avoid the influence of the overcurrent protection on the system state.
According to the application, through the soft turn-off time control unit composed of the current source 205, the soft turn-off bias current generation unit 206 and the first resistor 11, the soft turn-off time can be adjusted according to the voltage SSD _ VBIAS formed on the second resistor 12 by the current obtained by subtracting the soft turn-off bias current Ibias1 generated by the soft turn-off bias current generation unit 206 from the current Ibias0 generated by the current source 205, when overcurrent is serious, the sampling signal OC _ SENSE of a controlled module is large, and the duration of the soft turn-off time SSD _ time is long. When the overcurrent is small, the sampling signal OC _ SENSE of the controlled module is smaller, and the soft turn-off time SSD _ time duration is short.
According to the method, the SSD current Inld1 related to the sampling signal OC _ SENSE of the controlled module can be generated on the third MOS tube 303, so that when overcurrent is large, OC _ SENSE is large, inld1 is small, and the IGBT closing speed is slow, so that the IGBT is protected from being impacted by VCE overvoltage. When the overcurrent of the IGBT is small, OC _ SENSE is small, inld1 is large, and the closing speed of the IGBT is high, so that the response speed of the system is improved when the overcurrent is not serious.
Further, an embodiment of the present application provides a security chip, including any one of the foregoing overcurrent protection circuits for adaptive soft off current, where the circuit is used to perform overcurrent protection on a controlled module. The security chip can also comprise an operation module, a communication management module, a power management module and the like. The safety chip can be provided with a plurality of self-adaptive soft-off current overcurrent protection circuits for driving the multi-path controlled modules. Specifically, the controlled module may be any one of an IGBT (Insulated Gate Bipolar Transistor) and a SiC (silicon carbide) power device.
An embodiment of the present application further provides an overcurrent protection device for adaptive soft off current, including any one of the above overcurrent protection circuits for adaptive soft off current, so as to implement an overcurrent protection function for adaptive soft off current. The overcurrent protection device of the self-adaptive soft turn-off current can be arranged in the safety chip and connected with the controlled module, and can also be arranged in any other electric system, so that the controlled module which needs to be driven in a related system is connected to realize overcurrent protection.
The invention solves the problem of overvoltage of the IGBT or the SIC caused by directly closing the power tube in the traditional scheme, and the IGBT is closed in a grading way by detecting the VCE voltage of the IGBT, thereby improving the VCE overvoltage of the IGBT under the condition of large-current application.
It is to be understood that the above description is intended to be illustrative, and not restrictive. Many embodiments and many applications other than the examples provided would be apparent to those of skill in the art upon reading the above description. The scope of the present teachings should, therefore, be determined not with reference to the above description, but should instead be determined with reference to the appended claims, along with the full scope of equivalents to which such claims are entitled. The disclosures of all articles and references, including patent applications and publications, are hereby incorporated by reference for all purposes. The omission in the foregoing claims of any aspect of subject matter that is disclosed herein is not a disclaimer of such subject matter, nor is it to be construed that the applicant does not consider such subject matter to be part of the disclosed subject matter.
Claims (11)
1. The overcurrent protection circuit of self-adaptation soft turn-off current, characterized by, includes:
the voltage comparison unit is used for inputting a reference voltage and a sampling signal of a controlled module, and the voltage comparison unit compares the reference voltage with the sampling signal of the controlled module to obtain a comparison result; under the enabling control of the pulse width modulation signal, the voltage comparison unit outputs an overcurrent protection signal according to the comparison result;
the soft turn-off signal generating unit is connected with the voltage comparing unit and is used for latching an overcurrent protection signal when the pulse width modulation signal is at a low level; the voltage comparison unit outputs the overcurrent protection signal when the overcurrent protection signal is the high level of the last pulse width modulation signal; the soft turn-off signal generating unit outputs a soft turn-off enabling signal when the pulse width modulation signal is at a low level;
and the soft turn-off control unit is connected with the soft turn-off signal generation unit and generates a driving control signal of the controlled module according to the soft turn-off enabling signal and the sampling signal of the controlled module.
2. The adaptive soft-off current overcurrent protection circuit according to claim 1, wherein the soft-off signal generation unit includes a first RS flip-flop, a delay unit, an and gate unit, a second RS flip-flop, and a soft-off time control unit;
the S input end of the first RS trigger is connected with the voltage comparison unit, and the first RS trigger is used for receiving the overcurrent protection signal output by the voltage comparison unit; the R input end of the first RS trigger is connected with an inverse signal of the pulse width modulation signal;
the delay unit is connected with the first RS trigger and the AND gate unit, and is used for delaying the output signal of the first RS trigger to obtain an overcurrent protection pulse width modulation delay signal; the AND gate unit performs AND logic judgment on the overcurrent protection pulse width modulation delay signal and an inverse signal of the pulse width modulation signal to obtain a logic judgment result, and inputs the logic judgment result to an S input end of the second RS trigger;
the R input end of the second RS trigger is connected with the soft turn-off time control unit; the second RS trigger outputs a soft off enable signal.
3. The adaptive soft off-current overcurrent protection circuit of claim 2,
the soft turn-off time control unit comprises a current source, a soft turn-off bias current generation unit and a first resistor;
the input end of the current source is connected with a power supply, the output end of the current source is connected with the first end of the soft turn-off bias current generating unit, and the second end of the soft turn-off bias current generating unit is connected to the ground GND through the first resistor;
the first end of the soft off bias current generating unit is connected to the R input end of the second RS trigger.
4. The adaptive soft-off current overcurrent protection circuit of claim 3, wherein the soft-off bias current generation unit comprises a first operational amplifier and a first MOS transistor;
the output end of the current source is connected with the drain electrode of the first MOS tube, and the source electrode of the first MOS tube is connected to the ground GND through the first resistor; the positive input end of the first operational amplifier is connected with the sampling signal of the controlled module, the reverse input end of the first operational amplifier is connected with the source electrode of the first MOS tube, and the output end of the first operational amplifier is connected with the grid electrode of the first MOS tube.
5. The adaptive soft off-current overcurrent protection circuit of claim 4,
the soft turn-off control unit comprises a second operational amplifier, a second resistor, a third resistor, a second MOS (metal oxide semiconductor) tube and a third MOS tube;
the positive input end of the second operational amplifier is respectively connected to the drain electrode of the first MOS transistor and one end of the second resistor, the other end of the second resistor is connected to the ground GND, the reverse input end of the second operational amplifier is connected to the source electrode of the second MOS transistor, and the enable end of the second operational amplifier is connected to the output end of the second RS trigger; the output end of the second operational amplifier is respectively connected to the grid electrode of the second MOS tube and the grid electrode of the third MOS tube;
the source electrode of the second MOS tube is connected to the ground GND through the third resistor; the source electrode of the third MOS tube is connected to the ground GND; the drain electrode of the second MOS tube is connected to the drain electrode of the third MOS tube, and the drain electrode of the third MOS tube is connected to the control end of the controlled module.
6. The adaptive soft off-current overcurrent protection circuit of claim 5, wherein the current of the second MOS transistor is represented as follows:
wherein, lnld 0 is the current of the second MOS transistor, SSD _ VBIAS is the voltage formed on the second resistor by the current, which is obtained by subtracting the soft-off bias current Ibias1 generated by the soft-off bias current generating unit from the current Ibias0 generated by the current source, and R3 is the resistance value of the third resistor.
7. The adaptive soft off-current overcurrent protection circuit of claim 5,
the current of the third MOS tube is expressed as follows:
the Inld1 is the current of the third MOS tube, K is a multiple of the chip size of the third MOS tube relative to the chip size of the second MOS tube, and the chip size refers to the width-to-length ratio of a chip; ibias0 is the current generated by the current source, OC _ SENSE is the sampling signal of the controlled module, R1 is the resistance value of the first resistor, R2 is the resistance value of the second resistor, and R3 is the resistance value of the third resistor.
8. The adaptive soft off-current overcurrent protection circuit of claim 5,
and the drain electrode of the third MOS tube is connected to the control end of the controlled module through a fourth resistor.
9. The adaptive soft off-current overcurrent protection circuit of claim 1, wherein the controlled module is any one of an IGBT or a silicon carbide power device.
10. An overcurrent protection device for self-adaptive soft off current, which is characterized by comprising the overcurrent protection circuit for self-adaptive soft off current as claimed in any one of claims 1 to 9.
11. A security chip, characterized by comprising the overcurrent protection circuit of the adaptive soft turn-off current of any one of claims 1 to 9.
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| CN202310057164.7A CN115811025B (en) | 2023-01-19 | 2023-01-19 | Overcurrent protection circuit, device and safety chip for self-adaptive soft-off current |
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| CN202310057164.7A CN115811025B (en) | 2023-01-19 | 2023-01-19 | Overcurrent protection circuit, device and safety chip for self-adaptive soft-off current |
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Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN109039113A (en) * | 2018-07-18 | 2018-12-18 | 深圳市稳先微电子有限公司 | A kind of Switching Power Supply and its control chip |
| CN113285426A (en) * | 2021-05-28 | 2021-08-20 | 深圳市微源半导体股份有限公司 | Overcurrent protection circuit and device |
| CN113852043A (en) * | 2021-11-10 | 2021-12-28 | 深圳达人高科电子有限公司 | Short-circuit protection circuit |
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Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN109039113A (en) * | 2018-07-18 | 2018-12-18 | 深圳市稳先微电子有限公司 | A kind of Switching Power Supply and its control chip |
| CN113285426A (en) * | 2021-05-28 | 2021-08-20 | 深圳市微源半导体股份有限公司 | Overcurrent protection circuit and device |
| CN113852043A (en) * | 2021-11-10 | 2021-12-28 | 深圳达人高科电子有限公司 | Short-circuit protection circuit |
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