Bus over-voltage and under-voltage protection circuit for electric power steering system of industrial vehicle

Abstract

The utility model discloses a bus over-voltage and under-voltage protection circuit used for an industrial vehicle electric power steering system, and the circuit is characterized in that a voltage dividing module is used for accessing a DC bus voltage in the industrial vehicle electric power steering system, and carrying out the voltage dividing of the DC bus voltage; the threshold setting module is also used for setting an overvoltage threshold and an undervoltage threshold; the overvoltage comparison module and the hysteresis comparison module respectively control the output of the corresponding comparator based on an overvoltage threshold and an undervoltage threshold; the single-chip microcomputer control module starts or stops the protection action according to the output of the first comparator and the second comparator. According to the utility model, the output of the comparator is controlled through the set over-voltage threshold and under-voltage threshold, and the protection action is started or stopped based on the output, so that the damage of over-voltage and under-voltage to the system is avoided, and the stability and the safety of the operation of the system are improved.

Description

Technical Field

[0001] The utility model relates to the field of electric power steering systems for industrial vehicles, in particular to a busbar over-voltage and under-voltage protection circuit for electric power steering systems for industrial vehicles. Background Art

[0002] In the electric power steering system of industrial vehicles, the stability of the bus voltage is crucial to the motor drive and the operation of the entire system. Too high a voltage may damage the electronic components in the system, while too low a voltage will affect the normal operation of the motor or even cause the motor to stop. In the prior art, although there are some voltage protection circuits, most of them lack accurate voltage threshold settings and effective hysteresis comparison mechanisms, and cannot effectively deal with the instantaneous undervoltage phenomenon caused by load fluctuations, which can easily cause malfunctions and affect system stability and reliability. Utility Model Content

[0003] In order to protect the system from the harm of over-voltage and under-voltage, improve the stability and safety of system operation, and avoid the problem of instantaneous under-voltage caused by load fluctuation, which easily causes malfunction, the utility model proposes a busbar over-voltage and under-voltage protection circuit for an electric steering power system of an industrial vehicle, comprising:

[0004] The voltage divider module is used to access the DC bus voltage in the electric power steering system of industrial vehicles and divide the DC bus voltage; it is also used to set the overvoltage threshold and undervoltage threshold;

[0005] An overvoltage comparison module including a first comparator, used for comparing the output voltage of the voltage divider module with the overvoltage threshold, when the output voltage of the voltage divider module is higher than the overvoltage threshold, the output of the first comparator is switched from a low level to a high level;

[0006] A hysteresis comparison module including a second comparator, used for comparing the output voltage of the voltage divider module with the undervoltage threshold, when the output voltage of the voltage divider module is lower than the undervoltage threshold, the output of the second comparator is switched from a low level to a high level;

[0007] The single chip microcomputer control module is used to start or stop the protection action according to the output of the first comparator and the second comparator.

[0008] Furthermore, the bus over-voltage and under-voltage protection circuit also includes: a voltage filtering module, which is used to filter out high-frequency noise in the output voltage of the voltage divider module.

[0009] Furthermore, when the output voltage of the voltage divider module is less than the under-voltage threshold, the output of the second comparator switches to a high level; when the output voltage of the voltage divider module rises from a voltage value less than the under-voltage threshold to a reset threshold, the output of the second comparator switches to a low level; the reset threshold is higher than the under-voltage threshold.

[0010] Further, the voltage filtering module includes a fourth second capacitor C42;

[0011] The voltage dividing module includes: a sixth zero resistor R60, a sixth second resistor R62, a sixth third resistor R63, a sixth sixth resistor R66, a sixth seventh resistor R67 and a sixth eighth resistor R68;

[0012] One end of the sixth-second resistor R62 is connected to the DC bus voltage (24VCC), and the other end is connected to one end of the sixth-seventh resistor R67, and is connected to the non-inverting input terminal + of the first comparator U7C and the inverting input terminal - of the second comparator U7D; the other end of the sixth-seventh resistor R67 is connected to one end of the fourth-second capacitor C42 and then grounded; the other end of the fourth-second capacitor C42 is connected to the connecting line between the sixth-second resistor R62 and the sixth-seventh resistor R67; one end of the sixth zero resistor R60 is connected to the positive power supply (+5V), and the other end is connected to one end of the sixth-third resistor R63, and is connected to the inverting input terminal - of the first comparator U7C; the other end of the sixth-third resistor R63 is grounded; one end of the sixth-sixth resistor R66 is connected to the positive power supply (+5V), and the other end is connected to one end of the sixth-eighth resistor R68, and is connected to the non-inverting input terminal + of the second comparator; the other end of the sixth-eighth resistor R68 is grounded.

[0013] Furthermore, in the overvoltage comparison module:

[0014] The output end of the first comparator U7C is connected to one end of the fifth-ninth resistor R59 and one end of the sixth-first resistor R61 in sequence and then connected to the single-chip control module; the other end of the fifth-ninth resistor R59 is connected to the positive end of the eighth LED lamp L8 and then connected to the positive power supply (+5V); the other end of the sixth-first resistor R61 is connected to the negative end of the eighth LED lamp L8.

[0015] Furthermore, in the hysteresis comparison module:

[0016] The output end of the second comparator U7D is connected to one end of the sixty-fourth resistor R64, one end of the sixty-ninth resistor R69 and one end of the sixty-fifth resistor R65, and is connected to the single-chip microcomputer control module after being connected to one end of the sixty-fourth resistor R64 and one end of the sixty-fifth resistor R65; the other end of the sixty-fourth resistor R64 is connected to the positive terminal of the ninth LED lamp L9 and then connected to the positive power supply (+5V); the other end of the sixty-fifth resistor R65 is connected to the negative terminal of the ninth LED lamp L9; the other end of the sixty-ninth resistor R69 is connected to the same-phase input terminal + of the second comparator U7D.

[0017] Furthermore, the overvoltage threshold is set by a sixth zero resistor R60 and a sixth second resistor R62.

[0018] Furthermore, the undervoltage threshold is set by a sixth resistor R66.

[0019] Furthermore, the reset threshold is set by the sixth resistor R66, the sixth resistor R68 and the sixth resistor R69.

[0020] Furthermore, the voltage filtering module further includes:

[0021] A fourth third capacitor C43, used for filtering the outputs of the first comparator and the second comparator;

[0022] One end of the fourth capacitor C43 is connected to the positive power supply (+5V), and the other end is grounded.

[0023] Compared with the prior art, the utility model has at least the following beneficial effects:

[0024] (1) In the present invention, the voltage divider module is used to access the DC bus voltage in the electric power steering system of an industrial vehicle and divide the DC bus voltage; it is also used to set an overvoltage threshold and an undervoltage threshold; the overvoltage comparison module and the hysteresis comparison module control the output of the corresponding comparator based on the overvoltage threshold and the undervoltage threshold respectively; the single-chip microcomputer control module starts or stops the protection action according to the output of the first comparator and the second comparator; that is, the present invention controls the output of the comparator by setting the overvoltage threshold and the undervoltage threshold, and starts or stops the protection action based on the output, thereby avoiding the harm of overvoltage and undervoltage to the system and improving the stability and safety of the system operation;

[0025] (2) The utility model sets the overvoltage threshold through the sixth zero resistor R60 and the sixth second resistor R62, and sets the undervoltage threshold through the sixth sixth resistor R66, thereby achieving accurate setting of the voltage threshold;

[0026] (3) The utility model sets a reset threshold through the sixty-sixth resistor R66, the sixty-eighth resistor R68 and the sixty-ninth resistor R69; when the output voltage of the voltage divider module is less than the undervoltage threshold, the output of the second comparator switches to a high level, and when the output voltage of the voltage divider module rises from a voltage value less than the undervoltage threshold to a reset threshold, the output of the second comparator switches to a low level; the reset threshold is higher than the undervoltage threshold; that is, the utility model can effectively avoid malfunctions caused by instantaneous undervoltage caused by load fluctuations, thereby improving the stability and reliability of the system. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 The utility model discloses a bus over-voltage and under-voltage protection circuit diagram for an electric power steering system of an industrial vehicle. 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 protect the system from the harm of over-voltage and under-voltage, improve the stability and safety of system operation, and avoid the instantaneous under-voltage phenomenon caused by load fluctuation, which may easily cause malfunction problems, such as Figure 1 As shown, the utility model proposes a busbar over-voltage and under-voltage protection circuit for an electric power steering system of an industrial vehicle, comprising:

[0030] The voltage divider module is used to access the DC bus voltage in the electric power steering system of industrial vehicles and divide the DC bus voltage; it is also used to set the overvoltage threshold and undervoltage threshold;

[0031] An overvoltage comparison module including a first comparator, used for comparing the output voltage of the voltage divider module with the overvoltage threshold, when the output voltage of the voltage divider module is higher than the overvoltage threshold, the output of the first comparator is switched from a low level to a high level;

[0032] A hysteresis comparison module including a second comparator, used for comparing the output voltage of the voltage divider module with the undervoltage threshold, when the output voltage of the voltage divider module is lower than the undervoltage threshold, the output of the second comparator is switched from a low level to a high level;

[0033] When the output voltage of the voltage divider module is less than the under-voltage threshold, the output of the second comparator switches to a high level; when the output voltage of the voltage divider module rises from a voltage value less than the under-voltage threshold to a reset threshold, the output of the second comparator switches to a low level; the reset threshold is higher than the under-voltage threshold.

[0034] The busbar over-voltage and under-voltage protection circuit further includes: a voltage filtering module, which is used to filter out high-frequency noise in the output voltage of the voltage dividing module.

[0035] The voltage filtering module includes a fourth second capacitor C42; the voltage filtering module also includes:

[0036] A fourth third capacitor C43, used for filtering the outputs of the first comparator and the second comparator;

[0037] One end of the fourth capacitor C43 is connected to the positive power supply (+5V), and the other end is grounded.

[0038] The voltage dividing module includes: a sixth zero resistor R60, a sixth second resistor R62, a sixth third resistor R63, a sixth sixth resistor R66, a sixth seventh resistor R67 and a sixth eighth resistor R68;

[0039] One end of the sixth-second resistor R62 is connected to the DC bus voltage (24VCC), and the other end is connected to one end of the sixth-seventh resistor R67, and is connected to the non-inverting input terminal + of the first comparator U7C and the inverting input terminal - of the second comparator U7D; the other end of the sixth-seventh resistor R67 is connected to one end of the fourth-second capacitor C42 and then grounded; the other end of the fourth-second capacitor C42 is connected to the connecting line between the sixth-second resistor R62 and the sixth-seventh resistor R67; one end of the sixth zero resistor R60 is connected to the positive power supply (+5V), and the other end is connected to one end of the sixth-third resistor R63, and is connected to the inverting input terminal - of the first comparator U7C; the other end of the sixth-third resistor R63 is grounded; one end of the sixth-sixth resistor R66 is connected to the positive power supply (+5V), and the other end is connected to one end of the sixth-eighth resistor R68, and is connected to the non-inverting input terminal + of the second comparator; the other end of the sixth-eighth resistor R68 is grounded.

[0040] The over-voltage threshold is set by the sixth zero resistor R60 and the sixth second resistor R62.

[0041] The undervoltage threshold is set by the sixth resistor R66.

[0042] It should be noted that the reference voltage of the first comparator U7C, i.e., the overvoltage threshold, is set by the voltage-dividing resistors R60 and R62, so that when the DC bus voltage reaches 30V, the voltage after voltage division is 3V, i.e., the overvoltage threshold. The reference voltage of the second comparator U7D, i.e., the undervoltage threshold, is set by the resistor R66, and when the DC bus voltage is 18V, the voltage after voltage division is 1.8V, i.e., the undervoltage threshold. These two voltage values ​​(overvoltage threshold and undervoltage threshold) are statically set and are used to distinguish between the normal voltage range and the overvoltage or undervoltage state.

[0043] Specifically, the voltage protection range is >30v or <18v. According to the 10-fold scaling relationship of the voltage divider resistor, a voltage of 30V corresponds to an output of 3V, and 18V corresponds to an output of 1.8V. When the divided voltage is higher than 3V or lower than 1.8V, the corresponding comparator outputs a high-level signal to the microcontroller control module for protection processing. When the voltage returns to the normal range, the comparator restores the low voltage output.

[0044] Undervoltage comparison is different from overvoltage comparison. Undervoltage is sometimes caused by load fluctuation. To prevent this phenomenon, the undervoltage comparator, i.e., the second comparator U7D, adopts hysteresis comparison, that is, after the undervoltage signal (high level signal) is generated, the low level output must be restored only when the voltage after voltage division reaches the reset threshold.

[0045] In detail, in the second comparator U7D, the reset threshold is higher than the undervoltage threshold, and this difference forms a hysteresis window. The size of the hysteresis window depends on the configuration of the resistor network and can be set by adjusting the resistance values ​​of R68 and R69. That is, when the divided voltage drops and passes the undervoltage threshold, the output of the second comparator U7D switches to a high level. Then, as the voltage gradually recovers, it will not immediately cause the output of the comparator to return to a low level unless the voltage rises to the reset threshold. The reset threshold is determined by R66, R68 and R69, and usually forms a voltage divider network, in which R68 and R69 are used to adjust the voltage divider ratio to set a reset threshold higher than the undervoltage threshold. The size of the hysteresis window determines how much the voltage must fluctuate to cause a change in the output state of the second comparator U7D, which is very important to prevent small voltage fluctuations from causing unnecessary triggering of the protection circuit.

[0046] In the overvoltage comparison module:

[0047] The output end of the first comparator U7C is connected to one end of the fifth-ninth resistor R59 and one end of the sixth-first resistor R61 in sequence and then connected to the single-chip control module; the other end of the fifth-ninth resistor R59 is connected to the positive end of the eighth LED lamp L8 and then connected to the positive power supply (+5V); the other end of the sixth-first resistor R61 is connected to the negative end of the eighth LED lamp L8.

[0048] In the hysteresis comparison module:

[0049] The output end of the second comparator U7D is connected to one end of the sixty-fourth resistor R64, one end of the sixty-ninth resistor R69 and one end of the sixty-fifth resistor R65, and is connected to the single-chip microcomputer control module after being connected to one end of the sixty-fourth resistor R64 and one end of the sixty-fifth resistor R65; the other end of the sixty-fourth resistor R64 is connected to the positive terminal of the ninth LED lamp L9 and then connected to the positive power supply (+5V); the other end of the sixty-fifth resistor R65 is connected to the negative terminal of the ninth LED lamp L9; the other end of the sixty-ninth resistor R69 is connected to the same-phase input terminal + of the second comparator U7D.

[0050] The reset threshold is set by the sixth resistor R66, the sixth resistor R68 and the sixth resistor R69.

[0051] The single chip control module is used to start or stop the protection action (or protection circuit) according to the output of the first comparator and the second comparator.

[0052] It should be explained here that the protection action is a protection function turned on when the first comparator or the second comparator outputs a high level, including:

[0053] 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 industrial vehicle 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;

[0054] 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.

[0055] Send warning information: Through the CAN bus or other communication protocols, the microcontroller control module can send warnings to other components in the industrial vehicle electric power steering system or a central monitoring unit, indicating that an overvoltage or undervoltage condition has occurred.

[0056] In the utility model, the voltage divider module is used to access the DC bus voltage in the electric steering power-assist system of an industrial vehicle and divide the DC bus voltage; it is also used to set an overvoltage threshold and an undervoltage threshold; the overvoltage comparison module and the hysteresis comparison module control the output of the corresponding comparator based on the overvoltage threshold and the undervoltage threshold respectively; the single-chip computer control module starts or stops the protection action according to the output of the first comparator and the second comparator; that is, the utility model controls the output of the comparator by setting the overvoltage threshold and the undervoltage threshold, and starts or stops the protection action based on the output, thereby avoiding the harm of overvoltage and undervoltage to the system and improving the stability and safety of the system operation.

[0057] 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.

[0058] 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.

[0059] 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.

[0060] 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 over-voltage and under-voltage protection circuit for an electric power steering system of an industrial vehicle, characterized in that: include: A voltage divider module is used to access the DC bus voltage in the electric power steering system of industrial vehicles and divide the DC bus voltage; It is also used to set the overvoltage threshold and undervoltage threshold; An overvoltage comparison module including a first comparator, used for comparing the output voltage of the voltage divider module with the overvoltage threshold, when the output voltage of the voltage divider module is higher than the overvoltage threshold, the output of the first comparator is switched from a low level to a high level; A hysteresis comparison module including a second comparator, used for comparing the output voltage of the voltage divider module with the undervoltage threshold, when the output voltage of the voltage divider module is lower than the undervoltage threshold, the output of the second comparator is switched from a low level to a high level; The single chip microcomputer control module is used to start or stop the protection action according to the output of the first comparator and the second comparator.

2. A busbar over-voltage and under-voltage protection circuit for an electric power steering system of an industrial vehicle according to claim 1, characterized in that: The busbar over-voltage and under-voltage protection circuit further includes: a voltage filtering module, which is used to filter out high-frequency noise in the output voltage of the voltage dividing module.

3. A busbar over-voltage and under-voltage protection circuit for an electric power steering system of an industrial vehicle according to claim 2, characterized in that: When the output voltage of the voltage divider module is less than the undervoltage threshold, the output of the second comparator switches to a high level; when the output voltage of the voltage divider module rises from a voltage value less than the undervoltage threshold to a reset threshold, the output of the second comparator switches to a low level; the reset threshold is higher than the undervoltage threshold.

4. A busbar over-voltage and under-voltage protection circuit for an electric power steering system of an industrial vehicle according to claim 3, characterized in that: The voltage filtering module includes a fourth second capacitor C42; The voltage dividing module includes: a sixth zero resistor R60, a sixth second resistor R62, a sixth third resistor R63, a sixth sixth resistor R66, a sixth seventh resistor R67 and a sixth eighth resistor R68; One end of the sixth-second resistor R62 is connected to the DC bus voltage, and the other end is connected to one end of the sixth-seventh resistor R67, and is connected to the non-inverting input terminal + of the first comparator U7C and the inverting input terminal - of the second comparator U7D; the other end of the sixth-seventh resistor R67 is connected to one end of the fourth-second capacitor C42 and then grounded; the other end of the fourth-second capacitor C42 is connected to the connecting line between the sixth-second resistor R62 and the sixth-seventh resistor R67; one end of the sixth zero resistor R60 is connected to the positive power supply, and the other end is connected to one end of the sixth-third resistor R63, and is connected to the inverting input terminal - of the first comparator U7C; the other end of the sixth-third resistor R63 is grounded; one end of the sixth-sixth resistor R66 is connected to the positive power supply, and the other end is connected to one end of the sixth-eighth resistor R68, and is connected to the non-inverting input terminal + of the second comparator; the other end of the sixth-eighth resistor R68 is grounded.

5. A busbar over-voltage and under-voltage protection circuit for an electric power steering system of an industrial vehicle according to claim 4, characterized in that: In the overvoltage comparison module: The output end of the first comparator U7C is connected to one end of the fifth-ninth resistor R59 and one end of the sixth-first resistor R61 in sequence and then connected to the single-chip control module; the other end of the fifth-ninth resistor R59 is connected to the positive end of the eighth LED lamp L8 and then connected to the positive power supply; the other end of the sixth-first resistor R61 is connected to the negative end of the eighth LED lamp L8.

6. A busbar over-voltage and under-voltage protection circuit for an electric power steering system of an industrial vehicle according to claim 5, characterized in that: In the hysteresis comparison module: The output end of the second comparator U7D is connected to one end of the sixty-fourth resistor R64, one end of the sixty-ninth resistor R69 and one end of the sixty-fifth resistor R65, and is connected to the single-chip control module after being connected to one end of the sixty-fourth resistor R64 and one end of the sixty-fifth resistor R65; the other end of the sixty-fourth resistor R64 is connected to the positive terminal of the ninth LED lamp L9 and then connected to the positive power supply; the other end of the sixty-fifth resistor R65 is connected to the negative terminal of the ninth LED lamp L9; the other end of the sixty-ninth resistor R69 is connected to the in-phase input terminal + of the second comparator U7D.

7. A busbar over-voltage and under-voltage protection circuit for an electric power steering system of an industrial vehicle according to claim 6, characterized in that: The over-voltage threshold is set by the sixth zero resistor R60 and the sixth second resistor R62.

8. A busbar over-voltage and under-voltage protection circuit for an electric power steering system of an industrial vehicle according to claim 6, characterized in that: The undervoltage threshold is set by the sixth resistor R66.

9. A busbar over-voltage and under-voltage protection circuit for an electric power steering system of an industrial vehicle according to claim 6, characterized in that: The reset threshold is set by the sixth resistor R66, the sixth resistor R68 and the sixth resistor R69.

10. A busbar over-voltage and under-voltage protection circuit for an electric power steering system of an industrial vehicle according to claim 9, characterized in that: The voltage filtering module also includes: A fourth third capacitor C43, used for filtering the outputs of the first comparator and the second comparator; One end of the fourth capacitor C43 is connected to the positive power supply, and the other end is grounded.

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