Safety control circuit and control method thereof

Abstract

The invention discloses a safety control circuit and a control method thereof, and the safety control circuit comprises a control unit which is provided with an I / O pin; starting the switch unit; the level conversion processing circuit is connected to the output end of the I / O pin and the input end of the starting switch unit, and is used for performing level conversion on an output signal of the I / O pin to generate a stable control signal to control the starting switch unit; and the output end of the starting switch unit is connected to an external motor driving circuit. According to the technical scheme, when the control unit breaks down, the starting switch can be automatically triggered to be turned off, power output is cut off, and therefore the problem that due to the fact that the control unit is abnormal, the motor driving circuit continuously supplies power, and safety accidents are caused is solved.

Description

Technical Field

[0001] The present application relates to the field of circuit control technology, and in particular to a safety control circuit and a control method thereof. Background Art

[0002] In modern automotive electronic systems, motor drive control is widely used in various scenarios, such as electric power steering, air conditioning compressors, and window regulators. To ensure system reliability and safety, a power control switch (such as a MOS transistor) is typically installed in the motor drive circuit to promptly cut off power in the event of a fault, preventing more serious consequences such as short circuits, overcurrent, or component damage.

[0003] Traditional control methods typically use the MCU's standard IO ports to output high and low levels to control external logic circuits. For example, this involves turning on and off a MOSFET to control the power supply to a motor drive circuit. Under normal operating conditions, the MCU can flip the IO port level (high / low) based on detected fault signals (such as overcurrent or short circuit), triggering external circuitry to shut down the MOSFET, cutting off power and protecting the system.

[0004] However, when the MCU itself malfunctions (such as a freeze, reset error, or internal register disorder), its IO ports may be in an uncertain state (high, low, or floating), and may not flip as expected. In this case, if a serious fault occurs in the motor drive circuit, the system will not be able to effectively shut down the MOS transistor, causing continuous power supply to the faulty circuit, which may cause dangerous situations such as overheating, device burnout, or even fire. Summary of the Invention

[0005] The embodiment of the present application provides a safety control circuit and a control method thereof, which can automatically trigger the start switch to shut down and cut off the power output when the control unit itself fails, thereby avoiding the problem of safety accidents caused by continuous power supply to the motor drive circuit due to abnormality of the control unit.

[0006] In a first aspect, an embodiment of the present application provides a safety control circuit, the safety control circuit comprising:

[0007] A control unit having I / O pins;

[0008] Start the switch unit;

[0009] A level conversion processing circuit is connected to the output end of the I / O pin and the input end of the start switch unit, and is used to convert the output signal of the I / O pin to generate a stable control signal to control the start switch unit. The output end of the start switch unit is connected to the external motor drive circuit.

[0010] In one embodiment, the level conversion processing circuit includes a first resistor and a transistor control circuit, the first connection end of the first resistor is connected to the output end of the I / O pin and the input end of the transistor control circuit, the second connection end of the first resistor is grounded, and the output end of the transistor control circuit is connected to the input end of the start switch unit.

[0011] In one embodiment, the transistor control circuit includes a first transistor component, a second transistor component, and a third transistor component, wherein the first transistor component is connected to the output end of the I / O pin and the first resistor, the second transistor component is connected between the first transistor component and the third transistor component, and the third transistor component is connected to the input end of the start switch unit.

[0012] In one embodiment, the first transistor component and the second transistor component are NPN transistor components, and the third transistor component is a PNP transistor component.

[0013] In one embodiment, the level conversion processing circuit further includes a first capacitor connected to the first resistor, the output end of the I / O pin, and the input end of the first transistor component.

[0014] In one embodiment, the level conversion processing circuit further includes a filter circuit connected between the first transistor component and the second transistor component.

[0015] In one embodiment, the starting switch unit is a P-type MOSFET, the source of the P-type MOSFET is connected to the external motor drive circuit, the gate of the P-type MOSFET is connected to the third transistor assembly, and the drain of the P-type MOSFET is connected to the positive electrode of the power supply.

[0016] In a second aspect, an embodiment of the present application provides a safety control method, which is applied to the above-mentioned safety control circuit, and the safety control method includes:

[0017] Get the output signal of the I / O pin on the control unit;

[0018] Performing level conversion processing on the output signal to obtain a control signal output by the level conversion processing circuit;

[0019] The working state of the start switch unit is controlled according to the control signal.

[0020] In one embodiment, the control signal includes an on signal and an off signal;

[0021] The performing level conversion processing on the output signal to obtain the control signal output by the level conversion processing circuit includes:

[0022] When the output signal is at a high level, performing level conversion processing on the output signal, so that the control signal output by the level conversion processing circuit is a conduction signal;

[0023] When the output signal is at a low level, a level conversion process is performed on the output signal, and the control signal output by the level conversion processing circuit is a disconnection signal.

[0024] In one embodiment, the triode control circuit includes a first triode component, a second triode component, and a third triode component;

[0025] When the output signal is at a high level, performing level conversion processing on the output signal to obtain a control signal output by the level conversion processing circuit as a conduction signal includes:

[0026] When the output signal is at a high level, after level conversion processing is performed on the output signal, the first transistor assembly, the second transistor assembly, and the third transistor assembly are all in a conducting state, and the control signal output by the level conversion processing circuit is a conducting signal;

[0027] When the output signal is at a low level, performing level conversion processing on the output signal to obtain a control signal output by the level conversion processing circuit as a disconnection signal, comprising:

[0028] When the output signal is at a low level, after level conversion processing is performed on the output signal, the first transistor component, the second transistor component and the third transistor component are all in an off state, and the control signal output by the level conversion processing circuit is a disconnect signal.

[0029] The safety control circuit provided in the embodiment of the present application is configured such that a level conversion processing circuit is provided between the control unit and the start switch unit. Thus, even if the output signal of the I / O pin of the control unit becomes unstable due to a fault of the control unit itself, the level conversion processing circuit is used to perform level conversion on the output signal of the I / O pin of the control unit, thereby generating a stable control signal to control the start switch unit. That is, when a fault occurs in the control unit itself, the start switch can be automatically triggered to shut down, cutting off the power output, thereby avoiding the problem of a safety accident caused by continuous power supply to the motor drive circuit due to an abnormality of the control unit. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying any creative work.

[0031] Figure 1 A schematic diagram of a safety control circuit provided in one embodiment of the present application.

[0032] Figure 2 A flowchart of a security control method provided in one embodiment of the present application.

[0033] Description of Figure Numbers:

[0034] Control unit U1, first resistor R1, second resistor R2, third resistor R3, fourth resistor R4, fifth resistor R5, sixth resistor R6, seventh resistor R7, eighth resistor R8, first transistor Q1, second transistor Q2, second transistor Q3, start switch unit Q4, first capacitor C1, second capacitor C2.

[0035] The realization of the objectives, functional features and advantages of this application will be further explained in conjunction with embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0036] In order to make the purpose, technical solutions and advantages of this application clearer, the following part will further describe the embodiments of this application in detail with reference to the accompanying drawings.

[0037] When the following description refers to the accompanying drawings, unless otherwise indicated, the same numbers in different drawings represent the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with the present application. Instead, they are merely examples of devices and methods consistent with some aspects of the present application, as detailed in the appended claims.

[0038] In the description of this application, it should be understood that the terms "first", "second", etc. are used for descriptive purposes only and should not be understood as indicating or implying relative importance. For those of ordinary skill in the art, the specific meanings of the above terms in this application can be understood according to specific circumstances. In addition, in the description of this application, unless otherwise specified, "multiple" refers to two or more. "And / or" describes the association relationship of associated objects, indicating that three relationships may exist. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. The character " / " generally indicates that the previous and subsequent associated objects are in an "or" relationship.

[0039] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which this application belongs. The terms used in this specification are for the purpose of describing specific embodiments only and are not intended to limit this application. The term "and / or" as used herein includes any and all combinations of one or more of the relevant listed items.

[0040] See also Figure 1 The present application proposes a safety control circuit, which includes a control unit U1, a start switch unit Q4 and a level conversion processing circuit, wherein the control unit U1 has an I / O pin; the level conversion processing circuit is connected to the output end of the I / O pin and the input end of the start switch unit Q4, and is used to level-convert the output signal of the I / O pin to generate a stable control signal to control the start switch unit Q4, and the output end of the start switch unit Q4 is connected to an external motor drive circuit.

[0041] The safety control circuit provided in this embodiment provides a level conversion processing circuit between the control unit U1 and the start switch unit Q4. In this way, even if the output signal of the I / O pin of the control unit U1 becomes unstable due to a fault of the control unit U1 itself, the level conversion processing circuit can be used to convert the output signal of the I / O pin of the control unit U1 to generate a stable control signal to control the start switch unit Q4. That is, when the control unit itself fails, the start switch can be automatically triggered to shut down, cutting off the power output, thereby avoiding the problem of safety accidents caused by continuous power supply to the motor drive circuit due to an abnormality of the control unit.

[0042] In one embodiment, the level conversion processing circuit includes a first resistor R1 and a transistor control circuit, wherein a first connection end of the first resistor R1 is connected to the output end of the I / O pin and the input end of the transistor control circuit, a second connection end of the first resistor R1 is grounded, and the output end of the transistor control circuit is connected to the input end of the start switch unit Q4.

[0043] When the I / O pin of the control unit U1 is not driven or is in a high-impedance state (such as reset or sleep), if there is no pull-down resistor, namely the first resistor R1, the I / O pin may be in a floating state. In the floating state, the pin voltage will be affected by external interference, resulting in an uncertain level state, which may cause false triggering or other unpredictable behavior.

[0044] By connecting the first resistor R1 to ground, the I / O pin can be forced to a low level to avoid problems caused by a floating state.

[0045] Furthermore, even when the control unit U1 is operating normally, external electromagnetic interference may affect the I / O pins of the control unit U1. If the I / O pins do not have appropriate pull-down resistors, weak interference signals may cause the I / O pin voltage to fluctuate, leading to malfunctions.

[0046] The first resistor R1 can provide a certain load effect, so that the I / O pin is more stably maintained in a low level state, thereby enhancing the anti-interference capability of the circuit.

[0047] In addition, the first resistor R1 is connected between the transistor control circuit and the ground, which helps the transistor control circuit to quickly release the charge, so that the transistor control circuit can be turned off more quickly, thereby improving the response speed and stability.

[0048] In one embodiment, the transistor control circuit includes a first transistor component, a second transistor component, and a third transistor component, wherein the first transistor component is connected to the output end of the I / O pin and the first resistor R1, the second transistor component is connected between the first transistor component and the third transistor component, and the third transistor component is connected to the input end of the start switch unit Q4.

[0049] In one embodiment, the first transistor component and the second transistor component are NPN transistor components, and the third transistor component is a PNP transistor component.

[0050] In one embodiment, the first transistor assembly includes a first transistor Q1, a second resistor R2, and a third resistor R3; the second resistor R2 and the third resistor R3 are both connected to the base of the first transistor Q1, the emitter of the first transistor Q1 is connected to the second transistor assembly; and the collector of the first transistor Q1 is grounded.

[0051] In one embodiment, the second transistor assembly includes a second transistor Q2, a fifth resistor R5, and a sixth resistor R6; the fifth resistor R5 is connected to the first transistor assembly, and the fifth resistor R5 and the sixth resistor R6 are both connected to the base of the second transistor Q2; the emitter of the first transistor Q1 is grounded; and the collector of the second transistor Q2 is connected to the third transistor assembly.

[0052] In one embodiment, the third triode assembly includes a third triode, a seventh resistor R7, and an eighth resistor R8; the seventh resistor R7 is connected to the third triode assembly, and the seventh resistor R7 and the eighth resistor R8 are both connected to the base of the third triode; the emitter of the third triode is grounded; and the collector of the second triode Q2 is connected to the third triode assembly.

[0053] In one embodiment, the level conversion processing circuit further includes a first capacitor C1 , wherein the first capacitor C1 is connected to the first resistor R1 , the output end of the I / O pin, and the input end of the first transistor component.

[0054] Among them, the square wave signal output by the I / O pin now exhibits the characteristics of an AC signal at both ends of the first capacitor C1. Due to the characteristics of the first capacitor C1 that blocks DC and passes AC, the square wave signal passes through the first capacitor C1 and can output a DC signal with an amplitude lower than that of the square wave signal (the amplitude depends on the square wave frequency). When a hardware failure occurs in the control unit U1, the I / O pin cannot output a square wave signal. Regardless of the level state of the I / O pin at this time (high level, low level or floating state), its output signal no longer has AC characteristics, and all exhibits DC characteristics, and cannot pass through the first capacitor C1. At this time, no effective AC signal component can be obtained on the right side of the first capacitor C1, and the output level is pulled down to a certain low level.

[0055] Specifically, when the control unit U1 is in a normal state, the I / O pin outputs a square wave signal, and the first capacitor C1 outputs a high level. At this time, the first transistor Q1 is turned on, and the emitter of the first transistor Q1 outputs a 5V voltage. When the 5V signal output by the first transistor Q1 passes through the filtering circuit and reaches the base of the second transistor Q2, the second transistor Q2 is turned on, and the collector voltage is 0V. When the collector voltage of the second transistor Q2 is 0V, the third transistor Q3 is turned on and outputs 24V.

[0056] When a hardware failure occurs in the control unit U1, the first capacitor C1 outputs a low level. At this time, the first transistor Q1 is turned off, and the emitter outputs a 0V voltage. When the 0V signal output by the first transistor Q1 reaches the base of the second transistor Q2, the second transistor Q2 is turned off, and the collector voltage is 24V. When the collector voltage of the second transistor Q2 is 24V, the third transistor Q3 is turned off and outputs 0V.

[0057] In one embodiment, the level conversion processing circuit further includes a filter circuit connected between the first transistor component and the second transistor component.

[0058] The filter circuit includes a fourth resistor R4 and a second capacitor C2. The fourth resistor R4 is connected to the emitter of the first transistor Q1, the fifth resistor R5 and the second capacitor C2. The other end of the second capacitor C2 is grounded.

[0059] Due to the influence of the square wave frequency, the 5V level output by the first transistor Q1 will contain a small amount of high-frequency signal. After filtering by the fourth resistor R4 and the second capacitor C2, the high-frequency signal will be filtered out to obtain a relatively clean DC signal. Among them, the cutoff frequency, capacitance value, and resistance value of the filtering circuit depend on the size of the square wave frequency.

[0060] In one embodiment, the starting switch unit Q4 is a P-type MOSFET, the source of which is connected to the external motor driving circuit, the gate of which is connected to the third transistor assembly, and the drain of which is connected to the positive electrode of the power supply.

[0061] The external motor drive circuit includes an H-bridge. When the third transistor Q3 outputs 24V, the startup switch unit Q4 turns on, outputting 12V power to the H-bridge. When the third transistor Q3 outputs 0V, the startup switch unit Q4 turns off, shutting off the 12V power, thus preventing other serious consequences.

[0062] See also Figure 2 , an embodiment of the present application provides a safety control method, which is applied to the safety control circuit as described above, and the safety control method includes:

[0063] Step 110: Obtain the output signal of the I / O pin on the control unit U1.

[0064] The I / O pins of the control unit U1 are generated by a core software algorithm and continuously output a square wave signal. This square wave signal is implemented by the core program controlling the core to continuously flip the level. Compared to the traditional method of setting the I / O pin state to a fixed high or low level through programming, this solution can monitor the operating status of the control unit U1 core and the program in real time. If a core failure or program abnormality occurs, the square wave signal output will stop, triggering the corresponding protection mechanism.

[0065] In some embodiments, the frequency of the square wave signal may be 1 kHz and the duty cycle may be 50%.

[0066] It should be noted that the frequency of the square wave signal can be flexibly selected according to actual conditions.

[0067] Step 120: Performing level conversion processing on the output signal to obtain a control signal output by the level conversion processing circuit.

[0068] Step 130: Control the working state of the starting switch unit Q4 according to the control signal.

[0069] In one embodiment, the control signal includes an on signal and an off signal;

[0070] The performing level conversion processing on the output signal to obtain the control signal output by the level conversion processing circuit includes:

[0071] Step 121: When the output signal is at a high level, performing level conversion processing on the output signal, so that the control signal output by the level conversion processing circuit is a conduction signal;

[0072] Step 122: When the output signal is at a low level, performing level conversion processing on the output signal, and obtaining a control signal output by the level conversion processing circuit as a disconnection signal.

[0073] In one embodiment, the triode control circuit includes a first triode component, a second triode component, and a third triode component;

[0074] When the output signal is at a high level, performing level conversion processing on the output signal to obtain a control signal output by the level conversion processing circuit as a conduction signal includes:

[0075] When the output signal is at a high level, after level conversion processing is performed on the output signal, the first transistor assembly, the second transistor assembly, and the third transistor assembly are all in a conducting state, and the control signal output by the level conversion processing circuit is a conducting signal;

[0076] When the output signal is at a low level, performing level conversion processing on the output signal to obtain a control signal output by the level conversion processing circuit as a disconnection signal, comprising:

[0077] When the output signal is at a low level, after level conversion processing is performed on the output signal, the first transistor component, the second transistor component and the third transistor component are all in an off state, and the control signal output by the level conversion processing circuit is a disconnect signal.

[0078] Specifically, when the control unit U1 is in a normal state, the I / O pin outputs a square wave signal, and the first capacitor C1 outputs a high level. At this time, the first transistor Q1 is turned on, and the emitter of the first transistor Q1 outputs a 5V voltage. When the 5V signal output by the first transistor Q1 passes through the filtering circuit and reaches the base of the second transistor Q2, the second transistor Q2 is turned on, and the collector voltage is 0V. When the collector voltage of the second transistor Q2 is 0V, the third transistor Q3 is turned on and outputs 24V, that is, the first transistor assembly, the second transistor assembly and the third transistor assembly are all in the on state.

[0079] When a hardware failure occurs in the control unit U1, the first capacitor C1 outputs a low level. At this time, the first transistor Q1 is turned off, and the emitter outputs a 0V voltage. When the 0V signal output by the first transistor Q1 reaches the base of the second transistor Q2, the second transistor Q2 is turned off, and the collector voltage is 24V. When the collector voltage of the second transistor Q2 is 24V, the third transistor Q3 is turned off and outputs 0V, that is, the first transistor assembly, the second transistor assembly and the third transistor assembly are all in the off state.

[0080] In this way, the present application is based on the square wave signal output by the I / O pin. When the hardware platform and software program of the control unit U1 operate normally, after a series of logic level processing and conversion, the control switch, i.e., the start switch unit Q4, is turned on, and the power can be output normally to the H-bridge. When the hardware platform or software program of the control unit U1 does not operate normally, i.e., a fault occurs, the output signal of the I / O pin on the control unit U1 is converted by the level conversion processing circuit, and a stable control signal can be generated to control the start switch unit Q4. That is, when the control unit U1 itself fails, the start switch can be automatically triggered to turn off, cutting off the power output to the H-bridge, avoiding the problem of safety accidents caused by continuous power supply to the motor drive circuit due to abnormality of the control unit U1, so that the system is in a safe working state.

[0081] The same or similar numbers in the drawings of this embodiment correspond to the same or similar parts; in the description of this application, it should be understood that if the terms "up", "down", "left", "right", etc. indicate directions or positional relationships, they are based on the directions or positional relationships shown in the drawings. This is only for the convenience of describing this application and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific direction, be constructed and operated in a specific direction. Therefore, the terms describing the positional relationship in the drawings are only used for illustrative purposes and cannot be understood as limiting this application. For ordinary technicians in this field, the specific meanings of the above terms can be understood according to specific circumstances.

[0082] The above are only preferred embodiments of the present application and are not intended to limit the present application. Any modifications, equivalent replacements, and improvements made within the spirit and principles of the present application should be included in the scope of protection of the present application.

Claims

1. A safety control circuit, characterized in that: The safety control circuit comprises: A control unit having I / O pins; activating the switch unit; and A level conversion processing circuit is connected to the output end of the I / O pin and the input end of the start switch unit, and is used to convert the output signal of the I / O pin to generate a stable control signal to control the start switch unit. The output end of the start switch unit is connected to the external motor drive circuit.

2. The safety control circuit according to claim 1, wherein: The level conversion processing circuit includes a first resistor and a transistor control circuit, wherein a first connection end of the first resistor is connected to the output end of the I / O pin and the input end of the transistor control circuit, a second connection end of the first resistor is grounded, and the output end of the transistor control circuit is connected to the input end of the start switch unit.

3. The safety control circuit according to claim 2, wherein: The transistor control circuit includes a first transistor component, a second transistor component and a third transistor component, wherein the first transistor component is connected to the output end of the I / O pin and the first resistor, the second transistor component is connected between the first transistor component and the third transistor component, and the third transistor component is connected to the input end of the start switch unit.

4. The safety control circuit according to claim 3, wherein: The first transistor assembly and the second transistor assembly are NPN transistor assemblies, and the third transistor assembly is a PNP transistor assembly.

5. The safety control circuit according to claim 2, wherein: The level conversion processing circuit further includes a first capacitor connected to the first resistor, the output end of the I / O pin, and the input end of the first transistor component.

6. The safety control circuit according to claim 1, wherein: The level conversion processing circuit further includes a filter circuit connected between the first transistor component and the second transistor component.

7. The safety control circuit according to claim 2, wherein: The starting switch unit is a P-type MOS tube, the source of the P-type MOS tube is connected to the external motor drive circuit, the gate of the P-type MOS tube is connected to the third transistor assembly, and the drain of the P-type MOS tube is connected to the positive electrode of the power supply.

8. A safety control method, characterized in that: Applied to the safety control circuit according to any one of claims 1 to 7, the safety control method comprises: Get the output signal of the I / O pin on the control unit; Performing level conversion processing on the output signal to obtain a control signal output by the level conversion processing circuit; The working state of the start switch unit is controlled according to the control signal.

9. The safety control method according to claim 8, characterized in that: The control signal includes an on signal and an off signal; The performing level conversion processing on the output signal to obtain the control signal output by the level conversion processing circuit includes: When the output signal is at a high level, performing level conversion processing on the output signal, so that the control signal output by the level conversion processing circuit is a conduction signal; When the output signal is at a low level, a level conversion process is performed on the output signal, and the control signal output by the level conversion processing circuit is a disconnection signal.

10. The safety control method according to claim 9, wherein: The triode control circuit includes a first triode component, a second triode component and a third triode component; When the output signal is at a high level, performing level conversion processing on the output signal to obtain a control signal output by the level conversion processing circuit as a conduction signal includes: When the output signal is at a high level, after level conversion processing is performed on the output signal, the first transistor assembly, the second transistor assembly, and the third transistor assembly are all in a conducting state, and the control signal output by the level conversion processing circuit is a conducting signal; When the output signal is at a low level, performing level conversion processing on the output signal to obtain a control signal output by the level conversion processing circuit as a disconnection signal, comprising: When the output signal is at a low level, after level conversion processing is performed on the output signal, the first transistor component, the second transistor component and the third transistor component are all in an off state, and the control signal output by the level conversion processing circuit is a disconnect signal.

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