Bus overcurrent protection circuit for electric power steering system

Abstract

The utility model discloses a bus overcurrent protection circuit for an electric power steering system, which is characterized in that a ROUT resistor connected with a direct current bus in the electric power steering system is used for generating and outputting voltage drop, namely a voltage signal, which is in direct proportion to current; the resistance-capacitance filtering module is used for filtering the voltage signal output by the ROUT resistor; the signal amplification module is used for amplifying the filtered voltage signal; the over-current detection module is used for outputting a high-level signal to the single-chip microcomputer when the amplified voltage signal exceeds a reference threshold value; the single-chip microcomputer is used for triggering the protection action of the electric power steering system according to the output signal of the overcurrent detection module, so that the system is prevented from being damaged, and the safety of the electric power steering system is improved.

Description

Technical Field

[0001] The utility model relates to the field of electric power steering systems, in particular to a busbar overcurrent protection circuit for electric power steering systems. Background Art

[0002] In the electric power steering system of industrial vehicles, busbar overcurrent protection is a key link to ensure the safe operation of the system. Traditional overcurrent protection methods may not be suitable for all occasions due to cost or complexity, especially in scenarios where real-time current monitoring and rapid response are required. Utility Model Content

[0003] In order to reduce the cost of overcurrent protection, the utility model proposes a busbar overcurrent protection circuit for an electric power steering system, comprising:

[0004] Single chip microcomputer;

[0005] The ROUT resistor connected to the DC bus in the electric power steering system is used to generate and output a voltage drop proportional to the current, i.e., a voltage signal;

[0006] The RC filter module is used to filter the voltage signal output by the ROUT resistor;

[0007] A signal amplification module, used for amplifying the filtered voltage signal;

[0008] An overcurrent detection module is used to output a high level signal to the single chip microcomputer when the amplified voltage signal exceeds a reference threshold;

[0009] The single chip microcomputer is used to trigger the protection action of the electric power steering system according to the output signal of the overcurrent detection module.

[0010] Furthermore, the signal amplification module includes:

[0011] Operational amplifier U8B is used to amplify the filtered voltage signal and input it into the overcurrent detection module.

[0012] Furthermore, the overcurrent detection module includes:

[0013] The overcurrent comparator U7A is used to monitor the amplified voltage signal. When the amplified voltage signal exceeds the reference threshold, it outputs a high level signal to the microcontroller.

[0014] Furthermore, the RC filter module includes:

[0015] The primary filter unit is used to filter out high-frequency noise in the voltage signal output by the ROUT resistor.

[0016] Further, the primary filtering unit includes: a third fourth resistor R34 and a third seventh capacitor C37;

[0017] The RC filter module also includes:

[0018] The secondary filter unit includes: a 35th resistor R35, a 36th resistor R36, a 37th resistor R37, a 38th resistor R38, a 39th resistor R39, a 40th resistor R40, a 41st resistor R41, a 42nd resistor R42, a 43rd resistor R43, a 38th capacitor C38, a 39th capacitor C39 and a 40th capacitor C40; wherein:

[0019] One end of the fourth-first resistor R41 is connected to one end of the ROUT resistor, and the other end is connected to one end of the fourth-second resistor R42 and one end of the third-eight capacitor C38; the other end of the third-eight capacitor C38 is grounded; the other end of the fourth-second resistor R42 is connected to one end of the third-ninth capacitor C39 and then connected to the non-inverting input end of the operational amplifier U8B; the other end of the third-ninth capacitor C39 is grounded; one end of the third-ninth resistor R39 is grounded, and the other end is connected to the inverting input end of the operational amplifier U8B, and is connected to one end of the third-fourth resistor R34 and one end of the third-seventh capacitor C37; the negative power supply end of the operational amplifier U8B is connected to one end of the fourth zero capacitor C40 and then grounded, the positive power supply end is connected to the positive power supply (+5V), and the output end is connected to the positive end of the first-fifth diode D15; the negative end of the first-fifth diode D15 is connected to the other end of the fourth zero capacitor C40, the other end of the third-seventh capacitor C37 and the other end of the third-fourth resistor R34, and then connected to one end of the third-eighth resistor R38 , and then connected to one end of the third eight resistor R38 and connected to the non-inverting input end of the overcurrent comparator U7A; the other end of the third eight resistor R38 is connected to the power supply voltage VCC; one end of the fourth three resistor R43 is grounded, and the other end is connected to the inverting input end of the overcurrent comparator U7A, and then connected to one end of the third six resistor R36; the other end of the third six resistor R36 is connected to the positive power supply (+5V); the positive power supply end of the overcurrent comparator U7A is connected to the positive power supply (+5V), and the negative power supply end is grounded, The output end is connected to one end of the 35th resistor R35 and one end of the 37th resistor R37 in sequence, and then to one end of the 40th resistor R40; the other end of the 35th resistor R35 is connected to the positive end of the sixth LED lamp L6 and is connected to the positive power supply (+5V), and the negative end of the sixth LED lamp L6 is connected to the other end of the 37th resistor R37; the other end of the 40th resistor R40 is connected to the single-chip microcomputer; the other end of the ROUT resistor is connected to the DC bus in the electric steering power system.

[0020] Furthermore, the reference threshold is set by the third sixth resistor R36 and the third eighth resistor R38.

[0021] Furthermore, the operational amplifier U8B is specifically used to amplify the filtered voltage signal to 25 times.

[0022] Furthermore, the operational amplifier U8B is of model LM358.

[0023] Furthermore, the model of the overcurrent comparator U7A is LM339.

[0024] Furthermore, in the overcurrent comparator U7A, when the voltage at the inverting input terminal, i.e., the reference threshold, is lower than the voltage at the non-inverting input terminal, i.e., the amplified voltage signal, the overcurrent comparator switches from a low level output to a high level output; when the voltage at the non-inverting input terminal is lower than the set voltage at the inverting input terminal, the output of the overcurrent comparator U7A remains in a low level state.

[0025] Compared with the prior art, the utility model has at least the following beneficial effects:

[0026] The utility model comprises: a ROUT resistor connected to a DC bus in an electric power steering system, which is used for generating and outputting a voltage drop proportional to the current, namely, a voltage signal; a resistor-capacitor filter module, which is used for filtering the voltage signal output by the ROUT resistor; a signal amplification module, which is used for amplifying the filtered voltage signal; an overcurrent detection module, which is used for outputting a high-level signal to a single-chip microcomputer when the amplified voltage signal exceeds a reference threshold; the single-chip microcomputer is used for triggering a protection action of the electric power steering system according to the output signal of the overcurrent detection module, that is, the utility model obtains current information by connecting a ROUT resistor in series on the DC bus, and the voltage change at both ends of the resistor directly reflects the magnitude of the DC bus current; the output voltage of the ROUT resistor is processed by the resistor-capacitor filter module and the signal amplification module to adapt it to the input requirement of the single-chip microcomputer ADC, and is monitored in real time by the overcurrent detection module; when the amplified voltage signal exceeds the reference threshold, the single-chip microcomputer triggers the protection action of the electric power steering system in real time, so as to avoid the system from being damaged, thereby improving the safety of the electric power steering system. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 The utility model discloses a bus overcurrent protection circuit diagram for an electric power steering system. DETAILED DESCRIPTION

[0028] The following are specific embodiments of the present invention and the accompanying drawings to further describe the technical solution of the present invention, but the present invention is not limited to these embodiments.

[0029] In order to effectively detect the bus current and take protective measures in time to prevent system damage caused by overcurrent, such as Figure 1As shown, the utility model proposes a busbar overcurrent protection circuit for an electric power steering system, comprising:

[0030] Single chip microcomputer;

[0031] The ROUT resistor connected to the DC bus in the electric power steering system is used to generate and output a voltage drop proportional to the current, i.e., a voltage signal;

[0032] The RC filter module is used to filter the voltage signal output by the ROUT resistor;

[0033] A signal amplification module, used for amplifying the filtered voltage signal;

[0034] The signal amplification module comprises:

[0035] Operational amplifier U8B is used to amplify the filtered voltage signal and input it into the overcurrent detection module.

[0036] The operational amplifier U8B is specifically used to amplify the filtered voltage signal to 25 times.

[0037] The model of the operational amplifier U8B is LM358.

[0038] An overcurrent detection module is used to output a high level signal to the single chip microcomputer when the amplified voltage signal exceeds a reference threshold;

[0039] The overcurrent detection module comprises:

[0040] The overcurrent comparator U7A is used to monitor the amplified voltage signal. When the amplified voltage signal exceeds the reference threshold, it outputs a high level signal to the microcontroller.

[0041] The model of the overcurrent comparator U7A is LM339.

[0042] In the overcurrent comparator U7A, when the voltage at the inverting input terminal, i.e., the reference threshold, is lower than the voltage at the non-inverting input terminal, i.e., the amplified voltage signal, the overcurrent comparator switches from a low level output to a high level output; when the voltage at the non-inverting input terminal is lower than the set voltage at the inverting input terminal, the output of the overcurrent comparator U7A remains in a low level state.

[0043] The RC filter module comprises:

[0044] The primary filter unit is used to filter out high-frequency noise in the voltage signal output by the ROUT resistor.

[0045] The primary filter unit includes: a third fourth resistor R34 and a third seventh capacitor C37;

[0046] The RC filter module also includes:

[0047] The secondary filter unit for further purifying the signal includes: a 35th resistor R35, a 36th resistor R36, a 37th resistor R37, a 38th resistor R38, a 39th resistor R39, a 40th resistor R40, a 41st resistor R41, a 42nd resistor R42, a 43rd resistor R43, a 38th capacitor C38, a 39th capacitor C39 and a 40th capacitor C40; wherein:

[0048] One end of the fourth-first resistor R41 is connected to one end of the ROUT resistor, and the other end is connected to one end of the fourth-second resistor R42 and one end of the third-eight capacitor C38; the other end of the third-eight capacitor C38 is grounded; the other end of the fourth-second resistor R42 is connected to one end of the third-ninth capacitor C39 and then connected to the in-phase input terminal of the operational amplifier U8B; the other end of the third-ninth capacitor C39 is grounded; one end of the third-ninth resistor R39 is grounded, and the other end is connected to the inverting input terminal of the operational amplifier U8B, and is connected to one end of the third-fourth resistor R34 and one end of the third-seventh capacitor C37; the negative power supply terminal of the operational amplifier U8B is connected to one end of the fourth zero capacitor C40 and then grounded, the positive power supply terminal is connected to the positive power supply (+5V), and the output end is connected to the positive end of the first-fifth diode D15; the negative end of the first-fifth diode D15 is connected to the other end of the fourth zero capacitor C40, the other end of the third-seventh capacitor C37 and the other end of the third-fourth resistor R34, and then connected to one end of the third-eighth resistor R38, and is connected to One end of the third resistor R38 is connected to the in-phase input terminal of the overcurrent comparator U7A; the other end of the third resistor R38 is connected to the power supply voltage VCC; one end of the fourth resistor R43 is grounded, and the other end is connected to the inverting input terminal of the overcurrent comparator U7A, and then connected to one end of the third resistor R36; the other end of the third resistor R36 is connected to the positive power supply (+5V); the positive power supply terminal of the overcurrent comparator U7A is connected to the positive power supply (+5V), the negative power supply terminal is grounded, and the output terminal is connected to After one end of the 35th resistor R35 and one end of the 37th resistor R37 are connected, they are connected to one end of the 40th resistor R40; the other end of the 35th resistor R35 is connected to the positive end of the sixth LED lamp L6 and connected to the positive power supply (+5V), and the negative end of the sixth LED lamp L6 is connected to the other end of the 37th resistor R37; the other end of the 40th resistor R40 is connected to the AD sampling module in the single-chip computer; the other end of the ROUT resistor is connected to the DC bus in the electric steering power system.

[0049] Figure 1 In the example, there is also a Test2, which usually represents a test point or monitoring point in the circuit. During circuit design and debugging, the test point is used to facilitate engineers to access an oscilloscope or other test equipment to monitor the signal quality or behavior of the circuit at a specific point. Figure 1 In the example, Test2 is used to monitor the signal after amplification, or before the input of the overcurrent comparator U7A, to verify that the signal has been properly amplified to the expected level and that the signal is pure before overcurrent detection. This helps ensure the reliability and accuracy of overcurrent protection.

[0050] It should be noted that the electric power steering system includes power modules and power supplies of the control module. The power supply voltage VCC in this embodiment is the power supply of the power module.

[0051] The reference threshold is set by the third-sixth resistor R36 and the third-eighth resistor R38.

[0052] In this embodiment, the reference threshold is slightly higher than the maximum current under normal working conditions to avoid false alarms.

[0053] In the circuit, the reference threshold is usually provided by a fixed voltage source or a voltage divider network. In this embodiment, the third six resistors R36 and the third eight resistors R38 form a voltage divider to provide a stable reference voltage (i.e., the voltage corresponding to the reference threshold) to an input terminal of the overcurrent comparator U7A. The resistance ratio of R38 and R36 determines the size of the reference voltage, which is achieved through the voltage division principle. The size of the reference voltage directly affects the trigger threshold of the overcurrent comparator U7A, i.e., the reference threshold. In the circuit, the inverting input terminal of the overcurrent comparator U7A will be connected to this reference voltage, while the non-inverting input terminal receives the amplified voltage signal.

[0054] The single chip microcomputer is used to trigger the protection action of the electric power steering system according to the output signal of the overcurrent detection module.

[0055] When the DC bus current generates a corresponding voltage drop through the ROUT resistor, the signal will be filtered and amplified, and compared with the reference threshold set by R38 and R36. If the amplified voltage signal exceeds the reference threshold, the overcurrent comparator U7A will output a high level to trigger the overcurrent protection, that is, the protection action of the electric steering system.

[0056] It should be noted that the protection actions of the electric power steering system include but are not limited to the following actions:

[0057] Turn off the power drive, that is, stop sending pulse width modulation (PWM) signals or other control signals to the motor drive circuit of the electric power steering system, thereby preventing the motor drive circuit from supplying power to the motor; this can immediately stop the motor from running and prevent further electrical damage;

[0058] Cutting power to the motor physically disconnects the motor from the power source, ensuring that the motor cannot draw energy from the power source even if the drive circuit fails.

[0059] The utility model obtains current information (reducing current detection cost) by connecting a ROUT resistor in series on a DC bus. The voltage change at both ends of the resistor directly reflects the magnitude of the DC bus current. The output voltage of the ROUT resistor is processed by a resistor-capacitor filter module and a signal amplification module to adapt it to the input requirement of the single-chip ADC, and is monitored in real time by an overcurrent detection module. When the amplified voltage signal exceeds a reference threshold, the single-chip microcomputer triggers a protection action of the electric steering power system in real time to avoid damage to the system, thereby improving the safety of the electric steering power system.

[0060] It should be noted that all directional indications in the embodiments of the present invention (such as up, down, left, right, front, back, etc.) are only used to explain the relative position relationship, movement status, etc. between the components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.

[0061] In addition, in the present invention, descriptions such as "first", "second", "one", etc. are only used for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" or "second" may explicitly or implicitly include at least one of the features. In the description of the present invention, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0062] In the present invention, unless otherwise clearly specified and limited, the terms "connection", "fixation", etc. should be understood in a broad sense. For example, "fixation" can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0063] In addition, the technical solutions between the various embodiments of the present invention can be combined with each other, but it must be based on the fact that ordinary technicians in the field can implement it. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

Claims

1. A busbar overcurrent protection circuit for an electric power steering system, characterized in that: include: Single chip microcomputer; The ROUT resistor connected to the DC bus in the electric power steering system is used to generate and output a voltage drop proportional to the current, i.e., a voltage signal; The RC filter module is used to filter the voltage signal output by the ROUT resistor; A signal amplification module, used for amplifying the filtered voltage signal; An overcurrent detection module is used to output a high level signal to the single chip microcomputer when the amplified voltage signal exceeds a reference threshold; The single chip microcomputer is used to trigger the protection action of the electric power steering system according to the output signal of the overcurrent detection module.

2. A busbar overcurrent protection circuit for an electric power steering system according to claim 1, characterized in that: The signal amplification module comprises: Operational amplifier U8B is used to amplify the filtered voltage signal and input it into the overcurrent detection module.

3. A busbar overcurrent protection circuit for an electric power steering system according to claim 2, characterized in that: The overcurrent detection module comprises: The overcurrent comparator U7A is used to monitor the amplified voltage signal. When the amplified voltage signal exceeds the reference threshold, it outputs a high level signal to the microcontroller.

4. A busbar overcurrent protection circuit for an electric power steering system according to claim 3, characterized in that: The RC filter module comprises: The primary filter unit is used to filter out high-frequency noise in the voltage signal output by the ROUT resistor.

5. A busbar overcurrent protection circuit for an electric power steering system according to claim 4, characterized in that: The primary filter unit includes: a third fourth resistor R34 and a third seventh capacitor C37; The RC filter module also includes: The secondary filter unit includes: a 35th resistor R35, a 36th resistor R36, a 37th resistor R37, a 38th resistor R38, a 39th resistor R39, a 40th resistor R40, a 41st resistor R41, a 42nd resistor R42, a 43rd resistor R43, a 38th capacitor C38, a 39th capacitor C39 and a 40th capacitor C40; wherein: One end of the fourth-first resistor R41 is connected to one end of the ROUT resistor, and the other end is connected to one end of the fourth-second resistor R42 and one end of the third-eighth capacitor C38; the other end of the third-eighth capacitor C38 is grounded; the other end of the fourth-second resistor R42 is connected to one end of the third-ninth capacitor C39 and then connected to the non-inverting input end of the operational amplifier U8B; the other end of the third-ninth capacitor C39 is grounded; one end of the third-ninth resistor R39 is grounded, and the other end is connected to the inverting input end of the operational amplifier U8B, and is connected to one end of the third-fourth resistor R34 and one end of the third-seventh capacitor C37; the negative power supply end of the operational amplifier U8B is connected to one end of the fourth zero capacitor C40 and then grounded, the positive power supply end is connected to the positive power supply, and the output end is connected to the positive end of the first-fifth diode D15; the negative end of the first-fifth diode D15 is connected to the other end of the fourth zero capacitor C40, the other end of the third-seventh capacitor C37 and the other end of the third-fourth resistor R34, and then connected to the third-eighth resistor R38 one end of the overcurrent comparator U7A is connected, and after being connected to one end of the third eighth resistor R38, it is connected to the non-inverting input end of the overcurrent comparator U7A; the other end of the third eighth resistor R38 is connected to the power supply voltage VCC; one end of the fourth third resistor R43 is grounded, and the other end is connected to one end of the third sixth resistor R36 after being connected to the inverting input end of the overcurrent comparator U7A; the other end of the third sixth resistor R36 is connected to the positive power supply; the positive power supply end of the overcurrent comparator U7A is connected to the positive power supply, the negative power supply end is grounded, and the output end is connected to one end of the third fifth resistor R35 and one end of the third seventh resistor R37 in sequence, and then connected to one end of the fourth zero resistor R40; the other end of the third fifth resistor R35 is connected to the positive end of the sixth LED lamp L6 and is connected to the positive power supply, and the negative end of the sixth LED lamp L6 is connected to the other end of the third seventh resistor R37; the other end of the fourth zero resistor R40 is connected to the single-chip microcomputer; the other end of the ROUT resistor is connected to the DC bus in the electric steering power system.

6. A busbar overcurrent protection circuit for an electric power steering system according to claim 5, characterized in that: The reference threshold is set by the third-sixth resistor R36 and the third-eighth resistor R38.

7. A busbar overcurrent protection circuit for an electric power steering system according to claim 6, characterized in that: The operational amplifier U8B is specifically used to amplify the filtered voltage signal to 25 times.

8. The busbar overcurrent protection circuit for an electric power steering system according to claim 5, characterized in that: The model of the operational amplifier U8B is LM358.

9. The busbar overcurrent protection circuit for an electric power steering system according to claim 5, characterized in that: The model of the overcurrent comparator U7A is LM339.

10. A busbar overcurrent protection circuit for an electric power steering system according to claim 5, characterized in that: In the overcurrent comparator U7A, when the voltage at the inverting input terminal, i.e., the reference threshold, is lower than the voltage at the non-inverting input terminal, i.e., the amplified voltage signal, the overcurrent comparator switches from a low level output to a high level output; when the voltage at the non-inverting input terminal is lower than the set voltage at the inverting input terminal, the output of the overcurrent comparator U7A remains in a low level state.

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