Overcurrent latch protection circuit

Abstract

The utility model discloses an over-current latch protection circuit, which comprises a comparison unit, a charging and discharging unit and a switch control unit, the comparison unit is connected with the motor driving circuit and receives an output signal of the motor driving circuit so as to output a fault signal to close an enable signal of the motor driving circuit when the output signal is judged to be an overcurrent signal; the charging and discharging unit is connected with the comparison unit, and the charging and discharging unit charges when the comparison unit outputs the fault signal; the switch control unit is respectively connected with the comparison unit and the charging and discharging unit, controls the comparison unit to latch the overcurrent signal when the motor driving circuit outputs the overcurrent signal, and controls the comparison unit to output a normal signal to open an enable signal of the motor driving circuit after the charging and discharging unit is fully charged; therefore, the cost is low, the over-current signal response speed is high, and the self-recovery function is achieved, so that the circuit can be better protected.

Description

Technical Field

[0001] The utility model relates to the technical field of overcurrent protection, in particular to an overcurrent latch protection circuit. Background Art

[0002] In the related art, the most common form of damage to motor drives is overcurrent damage, so it is particularly important to provide reliable overcurrent protection for motor drives. The current overcurrent protection is mainly provided to the MCU through current sampling signals, so that the MCU can determine whether there is overcurrent and turn off the output after determining overcurrent. This method uses software protection, which may lead to untimely response and device damage. In addition, there are also driver chips or IPM modules with overcurrent latch alarms to achieve overcurrent protection. The current signal of the sampling resistor is first processed by a comparator, and then the compared high and low levels are provided to the driver chip or IPM internal comparator to trigger the fault output pin and turn off the output. However, this method must be implemented using a driver chip or IPM module with an overcurrent latch alarm, resulting in high circuit costs. Utility Model Content

[0003] The utility model aims to solve at least one of the technical problems in the above-mentioned technology to a certain extent. To this end, the purpose of the utility model is to provide an overcurrent latch protection circuit, which is not only low in cost and fast in response to overcurrent signals, but also has a self-recovery function, so as to better protect the circuit.

[0004] To achieve the above-mentioned purpose, the utility model proposes an overcurrent latch protection circuit, comprising: a comparison unit, the comparison unit is connected to a motor drive circuit, the comparison unit is used to receive an output signal of the motor drive circuit, so as to output a fault signal to turn off an enable signal of the motor drive circuit when the output signal is judged to be an overcurrent signal; a charge and discharge unit, the charge and discharge unit is connected to the comparison unit, the charge and discharge unit is charged when the comparison unit outputs a fault signal; a switch control unit, the switch control unit is respectively connected to the comparison unit and the charge and discharge unit, the switch control unit controls the comparison unit to latch the overcurrent signal when the motor drive circuit outputs an overcurrent signal, and controls the comparison unit to output a normal signal to turn on the enable signal of the motor drive circuit after the charge and discharge unit is fully charged.

[0005] According to the overcurrent latch protection circuit proposed by the utility model, the comparison unit is connected to the motor drive circuit to receive the output signal of the motor drive circuit, so as to output a fault signal to turn off the enable signal of the motor drive circuit when the output signal is judged to be an overcurrent signal; the charging and discharging unit is connected to the comparison unit, and the charging and discharging unit is charged when the comparison unit outputs a fault signal; the switch control unit is respectively connected to the comparison unit and the charging and discharging unit, and the switch control unit controls the comparison unit to latch the overcurrent signal when the motor drive circuit outputs an overcurrent signal, and controls the comparison unit to output a normal signal to turn on the enable signal of the motor drive circuit after the charging and discharging unit is fully charged; thereby, not only the cost is low, the response speed to the overcurrent signal is fast, but also the self-recovery function is provided, so that the circuit can be better protected.

[0006] In addition, the overcurrent latch protection circuit proposed in the present invention may also have the following additional technical features:

[0007] Optionally, the overcurrent latch protection circuit also includes a main control unit, which is respectively connected to the comparison unit and the motor drive circuit, and is used to receive a fault signal sent by the comparison unit, and control the motor drive circuit to stop working when the number of received fault signals is greater than a preset threshold.

[0008] Optionally, the comparison unit includes: a comparator, a first input terminal of the comparator having a preset voltage, and an output terminal of the comparator being used to output the fault signal or the normal signal; a first resistor, one end of the first resistor being connected to the second input terminal of the comparator, and the other end of the first resistor being used to receive the output signal of the motor drive circuit; a second resistor, one end of the second resistor being connected to the second input terminal, and the other end of the second resistor being connected to ground.

[0009] Optionally, the switch control unit includes: a transistor, the emitter of the transistor is connected to a power supply, and the collector of the transistor is connected to the other end of the first resistor; a third resistor, one end of the third resistor is connected to the emitter of the transistor, and the other end of the third resistor is connected to the base of the transistor; a first capacitor, one end of the first capacitor is connected to one end of the third resistor, and the other end of the first capacitor is connected to the other end of the third resistor.

[0010] Optionally, the charge and discharge unit includes: a Zener diode, a cathode of which is connected to the other end of the third resistor; a fourth resistor, one end of which is connected to the positive electrode of the Zener diode; a diode, a cathode of which is connected to one end of the third resistor, and a positive electrode of which is connected to the other end of the fourth resistor; and a second capacitor, one end of which is connected to the anode of the diode, and the other end of which is connected to the output end of the comparator.

[0011] Specifically, the transistor is a PNP transistor.

[0012] Specifically, the latching time can be adjusted by the parameter values ​​of the fourth resistor and the second capacitor. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 The schematic diagram of the circuit of the overcurrent latch protection circuit according to one embodiment of the utility model;

[0014] Figure 2 The figure is a system principle block diagram of an overcurrent latch protection circuit according to an embodiment of the utility model. DETAILED DESCRIPTION

[0015] The embodiments of the present invention are described in detail below, and examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present invention, and should not be construed as limiting the present invention.

[0016] In order to better understand the above technical solution, exemplary embodiments of the present invention will be described in more detail below with reference to the accompanying drawings. Although exemplary embodiments of the present invention are shown in the accompanying drawings, it should be understood that the present invention can be implemented in various forms and should not be limited by the embodiments described herein. On the contrary, these embodiments are provided to enable a more thorough understanding of the present invention and to fully convey the scope of the present invention to those skilled in the art.

[0017] In order to better understand the above technical solution, the above technical solution will be described in detail below in conjunction with the accompanying drawings and specific implementation methods.

[0018] refer to Figure 1-2 As shown, the over-current latch protection circuit proposed in the embodiment of the utility model includes a comparison unit 10 , a charge and discharge unit 20 and a switch control unit 30 .

[0019] Among them, the comparison unit 10 is connected to the motor drive circuit 50, and the comparison unit 10 is used to receive the output signal of the motor drive circuit 50, so as to output a fault signal to turn off the enable signal of the motor drive circuit 50 when the output signal is judged to be an overcurrent signal; the charging and discharging unit 20 is connected to the comparison unit 10, and the charging and discharging unit 20 is charged when the comparison unit 10 outputs a fault signal; the switch control unit 30 is respectively connected to the comparison unit 10 and the charging and discharging unit 20, and the switch control unit 30 controls the comparison unit 10 to latch the overcurrent signal when the motor drive circuit 50 outputs an overcurrent signal, and controls the comparison unit 10 to output a normal signal to turn on the enable signal of the motor drive circuit 50 after the charging and discharging unit 20 is fully charged.

[0020] That is to say, when the motor drive circuit 50 is in a normal state without overcurrent, the comparison unit 10 outputs a normal signal so that the motor drive circuit 50 obtains a signal allowing operation; when in an overcurrent state, the comparison unit 10 outputs a fault signal after receiving the overcurrent signal to turn off the signal allowing operation of the motor drive circuit 50, and charges through the charge and discharge unit 20, thereby controlling the switch control unit 30 to turn on to latch the overcurrent signal, and after being fully charged, the switch control unit 30 is closed to allow the comparison unit 10 to output a normal signal, thereby automatically restoring to normal. Therefore, the overcurrent latch protection circuit can not only latch and shut down the drive output first, but also automatically recover after a certain period of time. It is implemented by hardware and has high reliability.

[0021] As an embodiment, it also includes a main control unit 40, which is respectively connected to the comparison unit 10 and the motor drive circuit 50. The main control unit 40 is used to receive a fault signal sent by the comparison unit 10, and control the motor drive circuit 50 to stop working when the number of received fault signals is greater than a preset threshold.

[0022] That is to say, in the overcurrent state, the comparison unit 10 also sends a fault signal to the main control unit 40, so that the motor drive circuit 50 can be controlled by the main control unit 40 to stop working, thereby adopting a combination of software and hardware. By adding an overcurrent latch protection circuit to first latch and close the drive output protection circuit, and then the main control unit 40 determines whether to turn off the SPWM signal, so as to avoid failure abnormalities due to low software timeliness.

[0023] As an embodiment, the comparison unit 10 includes a comparator U1 , a first resistor R1 , and a second resistor R2 .

[0024] Among them, the first input terminal of the comparator U1 has a preset voltage Vref, and the output terminal of the comparator U1 is used to output a fault signal or a normal signal; one end of the first resistor R1 is connected to the second input terminal of the comparator U1, and the other end of the first resistor R1 is used to receive the output signal of the motor drive circuit 50; one end of the second resistor R2 is connected to the second input terminal, and the other end of the second resistor R2 is connected to the ground GND.

[0025] It should be noted that if Figure 1 As shown, the first resistor R1 plays the role of voltage division and current limiting, and the second resistor R2 is a pull-down resistor; the first input terminal is a positive input terminal, and the second input terminal is a negative input terminal. When the signal SC received by the second input terminal is greater than the preset voltage Vref, the comparator U1 outputs a low level, that is, outputs a fault signal; when the signal SC received by the second input terminal is less than the preset voltage Vref, the comparator U1 outputs a high level, that is, outputs a normal signal.

[0026] As an embodiment, the switch control unit 30 includes a transistor Q1 , a third resistor R3 , and a first capacitor C1 .

[0027] Among them, the emitter of the transistor Q1 is connected to the power supply, and the collector of the transistor Q1 is connected to the other end of the first resistor R1; one end of the third resistor R3 is connected to the emitter of the transistor Q1, and the other end of the third resistor R3 is connected to the base of the transistor Q1; one end of the first capacitor C1 is connected to one end of the third resistor R3, and the other end of the first capacitor C1 is connected to the other end of the third resistor R3.

[0028] It should be noted that the transistor Q1 is a PNP transistor, which acts as a switch tube; the third resistor R3 and the first capacitor C1 are used for the base and emitter of the transistor Q1, so that the transistor Q1 can work reliably.

[0029] As an embodiment, the charge and discharge unit 20 includes a voltage regulator tube ZD1, a fourth resistor R4, a diode D1 and a second capacitor C2.

[0030] Among them, the cathode of the voltage regulator ZD1 is connected to the other end of the third resistor R3; one end of the fourth resistor R4 is connected to the anode of the voltage regulator ZD1; the cathode of the diode D1 is connected to one end of the third resistor R3, and the anode of the diode D1 is connected to the other end of the fourth resistor R4; one end of the second capacitor C2 is connected to the anode of the diode D1, and the other end of the second capacitor C2 is connected to the output end of the comparator U1.

[0031] As an embodiment, the latching time can be adjusted by the parameter values ​​of the fourth resistor R4 and the second capacitor C2.

[0032] It should be noted that the third resistor R3, the voltage regulator ZD1, the fourth resistor R4 and the second capacitor C2 form an RC charging circuit, the diode D1 and the second capacitor C2 form a discharging circuit, and the latching time can be adjusted by adjusting the parameters of the fourth resistor R4 and the second capacitor C2.

[0033] That is to say, in a normal state, there is no overcurrent signal SC, the negative input terminal of the comparator U1 is grounded, and the output is a high level; when an overcurrent occurs in the motor drive, the overcurrent signal SC enters the negative input terminal of the comparator U1, and the output of the comparator U1 is pulled low; VDD charges the second capacitor C2 through the third resistor R3, the voltage regulator ZD1, and the fourth resistor R4; at the same time, the transistor Q1 is turned on, and VDD flows through the transistor Q1 to reach the negative input terminal of the comparator U1, so that the output of the comparator U1 is continuously pulled low; in this way, the comparator U1 can latch the SC signal, and output the FO signal to turn off the drive enable signal to protect the motor drive circuit; the fault signal is simultaneously fed back to the MCU for judgment, and when a certain number of times is reached, the SPWM signal is stopped from being output; when the fourth capacitor C4 is fully charged, the transistor Q1 is turned off, the negative input terminal of the comparator U1 is pulled low, and the output of the comparator U1 becomes a high level, and the normal state is restored.

[0034] In summary, according to the overcurrent latch protection circuit proposed in the utility model, the comparison unit is connected to the motor drive circuit to receive the output signal of the motor drive circuit so as to output a fault signal to turn off the enable signal of the motor drive circuit when the output signal is judged to be an overcurrent signal; the charging and discharging unit is connected to the comparison unit, and the charging and discharging unit is charged when the comparison unit outputs a fault signal; the switch control unit is respectively connected to the comparison unit and the charging and discharging unit, and the switch control unit controls the comparison unit to latch the overcurrent signal when the motor drive circuit outputs an overcurrent signal, and controls the comparison unit to output a normal signal to turn on the enable signal of the motor drive circuit after the charging and discharging unit is fully charged; thus, not only the cost is low and the response speed to the overcurrent signal is fast, but also the self-recovery function is provided, so that the circuit can be better protected.

[0035] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present invention.

[0036] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present utility model, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0037] In the present invention, unless otherwise clearly specified and limited, the terms "install", "connect", "connect", "fix" and the like should be understood in a broad sense, for example, it 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. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0038] In the present utility model, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may include that the first and second features are in direct contact, or may include that the first and second features are not in direct contact but are in contact through another feature between them. Moreover, a first feature being "above", "above" and "above" a second feature includes that the first feature is directly above and obliquely above the second feature, or simply indicates that the first feature is higher in level than the second feature. A first feature being "below", "below" and "below" a second feature includes that the first feature is directly below and obliquely below the second feature, or simply indicates that the first feature is lower in level than the second feature.

[0039] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the utility model. In this specification, the schematic representation of the above terms should not be understood as necessarily being directed to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine different embodiments or examples described in this specification.

[0040] Although the embodiments of the present invention have been shown and described above, it can be understood that the above embodiments are exemplary and cannot be understood as limitations of the present invention. Ordinary technicians in the field can change, modify, replace and modify the above embodiments within the scope of the present invention.

Claims

1. An overcurrent latch protection circuit, characterized in that: include: A comparison unit, the comparison unit is connected to the motor drive circuit, and the comparison unit is used to receive the output signal of the motor drive circuit, so as to output a fault signal to turn off the enable signal of the motor drive circuit when the output signal is judged to be an overcurrent signal; A charging and discharging unit, wherein the charging and discharging unit is connected to the comparing unit, and the charging and discharging unit is charged when the comparing unit outputs a fault signal; A switch control unit, wherein the switch control unit is connected to the comparison unit and the charge-discharge unit respectively, and the switch control unit controls the comparison unit to latch the overcurrent signal when the motor drive circuit outputs the overcurrent signal, and controls the comparison unit to output a normal signal to turn on the enable signal of the motor drive circuit after the charge-discharge unit is fully charged.

2. The overcurrent latch protection circuit according to claim 1, characterized in that: It also includes a main control unit, which is connected to the comparison unit and the motor drive circuit respectively. The main control unit is used to receive a fault signal sent by the comparison unit and control the motor drive circuit to stop working when the number of received fault signals is greater than a preset threshold.

3. The overcurrent latch protection circuit as claimed in claim 2, characterized in that: The comparison unit comprises: A comparator, wherein a first input terminal of the comparator has a preset voltage, and an output terminal of the comparator is used to output the fault signal or the normal signal; a first resistor, one end of the first resistor being connected to the second input end of the comparator, and the other end of the first resistor being used for receiving an output signal of the motor driving circuit; A second resistor, one end of the second resistor is connected to the second input end, and the other end of the second resistor is connected to the ground.

4. The overcurrent latch protection circuit according to claim 3, characterized in that: The switch control unit comprises: A triode, wherein the emitter of the triode is connected to a power supply, and the collector of the triode is connected to the other end of the first resistor; a third resistor, one end of the third resistor being connected to the emitter of the transistor, and the other end of the third resistor being connected to the base of the transistor; A first capacitor, one end of the first capacitor is connected to one end of the third resistor, and the other end of the first capacitor is connected to the other end of the third resistor.

5. The overcurrent latch protection circuit as claimed in claim 4, characterized in that: The charging and discharging unit comprises: A voltage regulator tube, wherein a cathode of the voltage regulator tube is connected to the other end of the third resistor; a fourth resistor, one end of which is connected to the positive electrode of the voltage regulator tube; a diode, wherein a cathode of the diode is connected to one end of the third resistor, and an anode of the diode is connected to the other end of the fourth resistor; A second capacitor, one end of the second capacitor is connected to the anode of the diode, and the other end of the second capacitor is connected to the output end of the comparator.

6. The overcurrent latch protection circuit according to claim 5, characterized in that: The transistor is a PNP transistor.

7. The overcurrent latch protection circuit according to claim 6, characterized in that: The latching time can be adjusted by the parameter values ​​of the fourth resistor and the second capacitor.

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