Motor driver protection circuit and low voltage motor driver

Abstract

The motor driver protection circuit and the low-voltage motor driver provided by the embodiments of the present application, the motor driver protection circuit comprises a motor driving circuit, the motor driving circuit comprises a sampling unit, the sampling unit is connected in series in a power main loop of the motor driving circuit, and the sampling unit is configured to collect a voltage signal of the power main loop; a short-circuit detection control circuit, the short-circuit detection control circuit comprises a voltage comparison unit and a fault latching unit, input ends of the voltage comparison unit are connected to both ends of the current collection unit, and an output end of the voltage comparison unit is connected to an input end of the fault latching unit; and a cut-off control unit, the cut-off control unit is connected in series in a control signal path of the motor driving circuit, an input end of the cut-off control unit is connected to an output end of the fault latching unit; when a short circuit occurs in the motor driving circuit, the cut-off control unit disconnects the control signal path of the motor driving circuit, thereby improving the circuit safety of the circuit provided with the low-voltage motor driver.

Description

Technical Field

[0001] This application relates to the field of circuit technology, and in particular to motor driver protection circuits and low-voltage motor drivers. Background Technology

[0002] In fields such as magnetic drive conveyors and small robots, low-voltage motor drivers are core actuators, typically using power switching devices such as MOSFETs to control motor operation. However, in practical applications, drivers are highly susceptible to short-circuit failures due to component failures, incorrect wiring, or load short circuits. Once a short circuit occurs, the current in the main power circuit can surge to hundreds of amperes within tens of microseconds, far exceeding the safe operating area (SOA) limit of the power switching devices. If the current cannot be interrupted in a very short time, it will cause the device to overheat and burn out, or even cause a fire. Existing technologies typically use fuses or digital protection schemes employing ADC sampling and MCU calculations for protection. However, because fuses have a melting time on the order of milliseconds, and digital protection schemes using ADC sampling and MCU calculations are subject to limitations in response speed due to the sampling period and the risk of protection failure due to software malfunctions, they cannot completely and effectively protect semiconductor devices, resulting in low safety in circuits equipped with low-voltage motor drivers. Utility Model Content

[0003] This utility model provides a motor driver protection circuit and a low-voltage motor driver, which can improve the safety of circuits equipped with low-voltage motor drivers.

[0004] To achieve the above objectives, a first aspect of this application provides a motor driver protection circuit, comprising:

[0005] A motor drive circuit, the motor drive circuit including a sampling unit connected in series in the power main circuit of the motor drive circuit, the sampling unit being used to collect the voltage signal of the power main circuit;

[0006] A short-circuit detection control circuit, comprising a voltage comparison unit and a fault latching unit, wherein a first input terminal of the voltage comparison unit is connected to a first terminal of the sampling unit, a second input terminal of the voltage comparison unit is connected to a second terminal of the sampling unit, and an output terminal of the voltage comparison unit is connected to an input terminal of the fault latching unit;

[0007] A cut-off control unit is connected in series in the control signal path of the motor drive circuit, and the input terminal of the cut-off control unit is connected to the output terminal of the fault latch unit.

[0008] When a short circuit occurs in the motor drive circuit, the voltage comparison unit outputs a high-level signal based on the voltage signal of the main power circuit. The input terminal of the fault latch unit outputs a high-level signal after detecting the high-level signal. The input terminal of the cut-off control unit disconnects the control signal path of the motor drive circuit after detecting the high-level signal.

[0009] In some embodiments, the sampling unit is a sampling resistor, which is connected in series between the power lower bridge arm and the power supply in the motor drive circuit.

[0010] In some embodiments, the short-circuit detection control circuit is provided with a filter resistor and a filter capacitor;

[0011] The first end of the filter resistor is connected to the first end of the sampling resistor, and the second end of the filter resistor is connected to the first input end of the voltage comparison unit.

[0012] The first end of the filter capacitor is connected to the second end of the filter resistor, and the second end of the filter capacitor is connected to the second end of the sampling resistor.

[0013] In some embodiments, the short-circuit detection control circuit is provided with a first voltage divider threshold resistor and a second voltage divider threshold resistor;

[0014] The first end of the first voltage divider threshold resistor is connected to the second end of the sampling resistor, and the second end of the first voltage divider threshold resistor is connected to the second input end of the voltage comparison unit.

[0015] The first end of the second voltage divider threshold resistor is connected to the power supply, and the second end of the second voltage divider threshold resistor is connected to the second input end of the voltage comparison unit.

[0016] In some embodiments, the short-circuit detection control circuit further includes a TVS diode, with the first end of the TVS diode connected to the second end of the filter resistor and the second end of the TVS diode connected to the second end of the sampling resistor.

[0017] In some embodiments, the input terminal of the fault latch unit includes a data input terminal and a clock input terminal, and the output terminal of the voltage comparison unit is connected to the data input terminal of the fault latch unit;

[0018] The short-circuit detection control circuit includes a delay circuit. The output terminal of the voltage comparison unit is connected to the first terminal of the delay circuit, and the second terminal of the delay circuit is connected to the clock input terminal of the fault latch unit.

[0019] In some embodiments, the delay circuit includes a delay resistor and a delay capacitor;

[0020] The first end of the delay resistor is connected to the output terminal of the voltage comparison unit, and the second end of the delay resistor is connected to the clock input terminal of the fault latch unit.

[0021] The first end of the delay capacitor is connected to the second end of the sampling resistor, and the second end of the delay capacitor is connected to the clock input of the fault latch unit.

[0022] In some embodiments, the short-circuit detection control circuit includes a pull-up resistor and a pull-down resistor;

[0023] The first end of the pull-up resistor is connected to the power supply, and the second end of the pull-up resistor is connected to the output end of the voltage comparison unit.

[0024] The first end of the pull-down resistor is connected to the second end of the sampling resistor, and the second end of the pull-down resistor is connected to the clock input of the fault latch unit.

[0025] In some embodiments, the motor drive circuit includes a control unit, and the short-circuit detection control circuit includes a first Schottky diode and a second Schottky diode;

[0026] The input terminal of the first Schottky diode is connected to the command interface of the control unit, and the output terminal of the first Schottky diode is connected to the first terminal of the delay resistor.

[0027] The input terminal of the second Schottky diode is connected to the output terminal of the voltage comparator unit, and the output terminal of the second Schottky diode is connected to the first terminal of the delay resistor;

[0028] The output of the fault latch unit is also connected to the reporting interface of the control unit.

[0029] In some embodiments, the motor drive circuit includes a control unit and a gate driver, wherein the cut-off control unit is a tri-state buffer connected in series on the pulse width modulation signal path between the control unit and the gate driver.

[0030] A second aspect of this application provides a low-voltage motor driver, including the motor driver protection circuit described in the first aspect.

[0031] The embodiments of this utility model include at least the following beneficial effects:

[0032] The motor driver protection circuit and low-voltage motor driver proposed in this application include a motor drive circuit, which includes a sampling unit connected in series in the main power circuit of the motor drive circuit, used to collect the voltage signal of the main power circuit; a short-circuit detection control circuit, which includes a voltage comparison unit and a fault latching unit, wherein the first input terminal of the voltage comparison unit is connected to the first terminal of the sampling unit, the second input terminal of the voltage comparison unit is connected to the second terminal of the sampling unit, and the output terminal of the voltage comparison unit is connected to the input terminal of the fault latching unit; and a disconnection control unit, which is connected in series in the control signal path of the motor drive circuit, with the input terminal of the disconnection control unit connected to the output terminal of the fault latching unit. When a short circuit occurs in the motor drive circuit, the voltage comparison unit outputs a high-level signal according to the voltage signal of the main power circuit, the input terminal of the fault latching unit outputs a high-level signal after detecting the high-level signal, and the input terminal of the disconnection control unit disconnects the control signal path of the motor drive circuit after detecting the high-level signal. Based on this, in this embodiment, the voltage comparison unit directly detects the current sampling signal at both ends of the sampling unit. The entire protection logic is executed by the hardware circuit, with a response time of up to microseconds. Once a short circuit occurs, the control signal path can be quickly cut off before the power device is damaged, thereby shutting off the main power circuit. This greatly improves the protection capability for semiconductor devices such as MOSFETs. Furthermore, by setting a fault latch unit, when a short circuit fault is triggered, the fault state is locked by hardware. Even if the short circuit disappears momentarily, the protection state is maintained, preventing the system from repeatedly restarting and causing secondary damage before the fault is eliminated. At the same time, the latched fault signal can be queried by the main controller, facilitating fault diagnosis and subsequent manual intervention, thus improving the system's safety and maintainability. In addition, in this application, there is no need for expensive ADCs, high-performance operational amplifiers, or complex MCUs to participate in protection decisions. Protection of the motor drive can be achieved using only low-cost voltage comparators, fault latch units, and buffers, which not only significantly reduces the material cost of the protection circuit but also simplifies circuit design and debugging. This is particularly suitable for cost-sensitive fields such as magnetic drive conveyors and small robots, thereby greatly improving the safety of circuits equipped with low-voltage motor drivers.

[0033] Other features and advantages of this invention will be set forth in the description which follows, and will be apparent in part from the description, or may be learned by practicing the invention. The objects and other advantages of this invention may be realized and obtained by means of the structures particularly pointed out in the description, claims, and drawings. Attached Figure Description

[0034] Figure 1 This is a schematic diagram of the structure of the motor driver protection circuit provided in the embodiment of this application.

[0035] Figure 2 This is a circuit diagram of a motor driver protection circuit provided in another embodiment of this application.

[0036] Figure 3 This is a functional flowchart of a motor driver protection circuit provided in another embodiment of this application.

[0037] Figure 4 This is a circuit diagram of a low-voltage motor driver provided in another embodiment of this application. Detailed Implementation

[0038] In the description of this utility model, it should be understood that the orientation descriptions, such as up, down, front, back, left, right, etc., are based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the embodiments of this utility model.

[0039] It should be understood that in the description of the embodiments of this utility model, "a few" means one or more, "multiple" means two or more, "greater than," "less than," and "exceeding" are understood to exclude the stated number, while "above," "below," and "within" are understood to include the stated number. If "first," "second," etc., are used in the description, they are only for the purpose of distinguishing technical features and should not be construed as indicating or implying relative importance, or implicitly indicating the number of indicated technical features, or implicitly indicating the sequential relationship of the indicated technical features.

[0040] In the description of the embodiments of this utility model, unless otherwise explicitly limited, terms such as setting, installation, and electrical connection should be interpreted broadly, and those skilled in the art can reasonably determine the specific meaning of the above terms in the embodiments of this utility model in conjunction with the specific content of the technical solution.

[0041] In the description of this utility model, the terms "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of this utility model. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0042] In fields such as magnetic drive conveyors and small robots, low-voltage motor drivers are core actuators, typically using power switching devices such as MOSFETs to control motor operation. However, in practical applications, drivers are highly susceptible to short-circuit failures due to component failures, incorrect wiring, or load short circuits. Once a short circuit occurs, the current in the main power circuit can surge to hundreds of amperes within tens of microseconds, far exceeding the safe operating area (SOA) limit of the power switching devices. If the current cannot be interrupted in a very short time, it will cause the device to overheat and burn out, or even cause a fire. Existing technologies typically use fuses or digital protection schemes employing ADC sampling and MCU calculations for protection. However, because fuses have a melting time on the order of milliseconds, and digital protection schemes using ADC sampling and MCU calculations are subject to limitations in response speed due to the sampling period and the risk of protection failure due to software malfunctions, they cannot completely and effectively protect semiconductor devices, resulting in low safety in circuits equipped with low-voltage motor drivers.

[0043] To improve the safety of circuits equipped with low-voltage motor drivers, this embodiment utilizes a voltage comparison unit to directly detect the current sampling signal across the sampling unit. The entire protection logic is executed by hardware circuitry, achieving a response time in the microsecond range. In the event of a short circuit, the control signal path can be quickly cut off before the power devices are damaged, thereby shutting down the main power circuit. This significantly enhances the protection capability for semiconductor devices such as MOSFETs. Furthermore, by incorporating a fault latching unit, the fault state is hardware-locked upon triggering a short-circuit fault. Even if the short circuit disappears momentarily, the protection state remains maintained, preventing secondary damage caused by repeated system restarts before the fault is resolved. In addition, the latched fault signal can be queried by the main controller, which facilitates fault diagnosis and subsequent manual intervention, improving the system's safety and maintainability. Furthermore, this application eliminates the need for expensive ADCs, high-performance operational amplifiers, or complex MCUs to participate in protection decisions. Protection of the motor drive can be achieved using only low-cost general-purpose components such as voltage comparators, fault latch units, and buffers. This not only significantly reduces the material cost of the protection circuit but also simplifies circuit design and debugging. It is particularly suitable for cost-sensitive fields such as magnetic drive conveyors and small robots, thereby greatly improving the safety of circuits equipped with low-voltage motor drivers.

[0044] This application provides a motor driver protection circuit and a low-voltage motor driver, which are specifically described through the following embodiments. First, the motor driver protection circuit is described.

[0045] To better describe the motor driver protection circuit provided in the embodiments of this application, in this embodiment, refer to Figure 1As shown, this application discloses the core technical concept of a motor driver protection circuit. The process begins with a sampling unit, which continuously and in real-time monitors the current in the main power circuit of the motor drive circuit and converts it into a voltage signal for judgment. Next, this signal is transmitted to the short-circuit detection control circuit. This motor driver protection circuit is the brain of the entire protection logic. Once an abnormal current in the motor drive circuit (i.e., a short circuit occurs) is detected, the motor driver protection circuit immediately generates and latches a fault command, and then quickly transmits the fault command to the top disconnection control unit. The disconnection control unit, as the final actuator, immediately disconnects the control signal path of the driver (such as a PWM signal), thereby shutting down the power device within microseconds, interrupting the short-circuit current, and ultimately achieving fast and reliable protection for the entire circuit.

[0046] based on Figure 1 The schematic diagram of the motor driver protection circuit shown is illustrated below. The motor driver protection circuit provided in the embodiments of this application will be further described below.

[0047] Reference Figure 2 This is a circuit diagram of the motor driver protection circuit provided in an embodiment of this application. Figure 2 As shown, the motor driver protection circuit includes a motor drive circuit, which mainly consists of a power supply, a power supply capacitor C1, a control unit MCU, a three-phase inverter bridge (composed of power switches Q1 to Q6), a three-phase inductor L1, and a gate driver U3 that provides drive signals to the three-phase inverter bridge. To monitor the circuit status in real time, a sampling unit is included in the motor drive circuit. This sampling unit can be implemented using a sampling resistor R1 (with a resistance value of 5mΩ). The sampling resistor R1 is connected in series in the main power circuit of the motor drive circuit, specifically between the common terminal of the lower arm of the three-phase inverter bridge and the power supply ground. This connection ensures that all currents flowing through the lower arm power switches (including Q2, Q4, and Q6) will flow through this sampling unit. According to Ohm's law, when the current in the main power circuit flows through the sampling unit, a voltage drop will be generated across its two ends, thus forming a voltage signal proportional to the magnitude of the main circuit current. This voltage signal can be used by the short-circuit detection control circuit connected to the sampling resistor R1 as a basis for judging whether the motor drive circuit is short-circuited.

[0048] In addition, such as Figure 2As shown, the motor driver protection circuit also includes a short-circuit detection control circuit, the core of which is a voltage comparison unit U1 and a fault latching unit U2. The first input terminal (i.e., the non-inverting input "+") of the voltage comparison unit is connected to the first terminal of the sampling resistor R1 through resistor R2 to receive a voltage signal reflecting the current magnitude. The second input terminal (i.e., the inverting input "-") of the voltage comparison unit is connected to the second terminal of the sampling unit through voltage divider resistors (R3 and R4) to receive a reference voltage, which essentially sets an overcurrent protection threshold. The output terminal of the voltage comparison unit U1 is connected to the input terminal (i.e., the data input terminal D) of the fault latching unit U2. This configuration allows the voltage comparison unit to continuously compare the real-time current sampling signal with the preset threshold.

[0049] In one example, voltage comparator unit U1 is a voltage comparator, model LM393DR2G, with a propagation delay of 300ns.

[0050] In some embodiments, a cutoff control unit is provided in the circuit to reliably cut off the drive after a fault is detected. In the embodiment shown in the accompanying drawings, the cutoff control unit U4 can be a tri-state buffer. This cutoff control unit is connected in series in the control signal path of the motor drive circuit; specifically, it is positioned between the pulse width modulation (PWM) signal output by the main controller U5 (MCU) and the input of the gate driver U3. The enable control input of the cutoff control unit U4 is connected to the output Q of the fault latch unit U2. In this way, the signal output by the fault latch unit U2 can directly determine whether the cutoff control unit U4 allows the control signal to pass or sets it to a high-impedance state to block signal transmission.

[0051] In one example, the tri-state buffer model used is SN74LVC245APWR. When the fault signal of the fault latch unit U2 is transmitted, the cut-off control unit U4 will cut off the PWM output, causing the gate driver U3 to force the MOSFET to turn off.

[0052] In some embodiments, when a short circuit occurs in the motor drive circuit, the current in the main power circuit increases sharply, causing the voltage signal across the sampling resistor R1 to rise rapidly. Upon receiving this increased voltage signal at the first input of the voltage comparator unit U1, once its value exceeds the threshold set at the second input, the output state of the voltage comparator unit flips, outputting a high-level signal. This high-level signal is sent to the input of the fault latch unit U2. Under the action of the corresponding clock signal (CLK), the input of the fault latch unit U2 detects the high-level signal, latches the fault state, and outputs a high-level signal from its output. Finally, upon detecting the high-level signal from the fault latch unit, the enable input of the cutoff control unit U4 immediately changes its operating state, disconnecting the control signal path of the motor drive circuit. This prevents the PWM drive signal from the control unit U5 from reaching the gate driver U3, thereby quickly turning off all power switches (Q1-Q6) and interrupting the short-circuit current.

[0053] In some embodiments, to ensure the accuracy of the current sampling signal, such as Figure 2 As shown, the short-circuit detection control circuit further includes a filter resistor R2 and a filter capacitor C2. Specifically, the first end of the filter resistor R2 is connected to the first end of the sampling resistor R1, while its second end is connected to the first input terminal of the voltage comparison unit U1. Simultaneously, the first end of the filter capacitor C2 is connected in parallel with the second end of the filter resistor R2, and its second end is connected to the second end (i.e., circuit ground) of the sampling resistor R1. This RC low-pass filter, composed of the filter resistor R2 and the filter capacitor C2, primarily filters out high-frequency noise and glitches superimposed on the current sampling signal due to motor PWM chopping or other electromagnetic interference. This provides the voltage comparison unit U1 with a smoother voltage signal that accurately reflects the average current level, effectively preventing false triggering of the circuit due to instantaneous noise interference and enhancing the stability of the protection action. In this embodiment, the resistance value of the filter resistor R2 is set to 100Ω, and the capacitance value of the filter capacitor C2 is set to 100pF.

[0054] In some embodiments, in order to precisely set the trigger threshold for short-circuit protection, such as Figure 2As shown, the short-circuit detection control circuit also includes a first voltage divider threshold resistor R3 and a second voltage divider threshold resistor R4. In terms of circuit connection, the first terminal of the second voltage divider threshold resistor R4 is connected to the power supply, and the first terminal of the first voltage divider threshold resistor R3 is connected to the second terminal (i.e., circuit ground) of the sampling resistor R1. The second terminals of both resistors are connected to the second input terminal of the voltage comparison unit U1. The first voltage divider threshold resistor R3 and the second voltage divider threshold resistor R4 together form a precise voltage divider network, which generates a stable and accurate reference voltage, serving as the judgment threshold for short-circuit protection. By adjusting the resistance values ​​of these two resistors, the overcurrent action point of the protection circuit can be flexibly and accurately set to adapt to different power levels of motors or different application scenarios.

[0055] In one example, the first voltage divider threshold resistor R3 is selected as 1kΩ, and the second voltage divider threshold resistor R4 is selected as 2.2kΩ. R3 and R4 form a voltage divider network and set the overcurrent threshold as shown in the following formula (1).

[0056]

[0057] In addition, such as Figure 2 As shown, the short-circuit detection control circuit also includes a protective TVS diode Q7. The first terminal of the protective TVS diode Q7 is connected to the first terminal of the voltage comparison unit U1, and its second terminal is connected to the first terminal of the first voltage divider threshold resistor R3. It is used to prevent the voltage comparison unit U1 from being broken down due to excessively high voltage spikes. The protective TVS diode Q7 can be of model SMD5.0A.

[0058] In some embodiments, to improve the circuit's shock resistance and overall reliability, such as Figure 2 As shown, a TVS diode, TVS1, is additionally provided in the short-circuit detection control circuit. This TVS diode is connected in parallel to the input terminal of the voltage comparator unit U1. Its first terminal is connected to the second terminal of the filter resistor R2, and its second terminal is connected to the second terminal of the sampling resistor R1. The TVS diode is a transient voltage suppression device, whose main function is to provide electrostatic discharge (ESD) or surge protection. In a motor drive system, when a severe surge current or external electrostatic discharge occurs, a transient high voltage far exceeding the normal operating range may be generated on the sampling signal path. At this time, the TVS diode will quickly conduct, clamping the excessively high voltage to a safe level and dissipating the transient energy to ground, thereby protecting the relatively vulnerable input pin of the subsequent voltage comparator unit from breakdown damage, significantly enhancing the robustness of the entire protection circuit in complex electromagnetic environments.

[0059] In this embodiment, the RC network composed of filter resistors and filter capacitors ensures that the signal sent to the comparator is pure and accurately reflects the load condition; the precise reference voltage set by the voltage divider resistor network guarantees the accuracy and consistency of the protection action; and the addition of the TVS diode provides the entire detection circuit with robust surge and electrostatic discharge (ESD) protection capabilities. The synergistic effect of these three components enables this protection circuit not only to perform its protection function stably and accurately, but also to withstand interference and shocks from harsh external electrical environments, thereby ensuring the long-term safety and reliability of the entire motor drive system.

[0060] In some embodiments, in order to achieve reliable locking of fault signals, such as Figure 2 As shown, the input terminals of the fault latch unit U2 include a data input terminal D and a clock input terminal CLK. In terms of circuit connection, the output terminal of the voltage comparator unit U1 is directly connected to the data input terminal D of the fault latch unit U2. This means that the instantaneous high-level fault signal generated by the voltage comparator unit U1 will be immediately displayed on the data input terminal D. Simultaneously, a delay circuit is also included in the short-circuit detection control circuit. The first terminal of this delay circuit also receives the fault signal from the output terminal of the voltage comparator unit U1, while its second terminal is connected to the clock input terminal CLK of the fault latch unit U2. This design, using the same fault signal source to drive both the data input terminal D and the delayed clock input terminal CLK, aims to create a timing difference, ensuring that the data signal has been stably established before the clock signal arrives. This satisfies the data setup time requirements of the D flip-flop, enabling reliable capture and latching of instantaneous fault signals.

[0061] In one example, the fault latch unit U2 is a D-type flip-flop, model 74LVC1G74. When a high level is detected at the D terminal, due to the delay of R6 and C3, a rising edge is detected at the CLK terminal approximately 1µs later, thus latching and transmitting the fault information. The truth table of the fault latch unit U2 is shown below.

[0062]

[0063] In some embodiments, such as Figure 2As shown, the delay circuit includes a delay resistor R6 and a delay capacitor C3. Specifically, the delay resistor R6 is connected in series between the output of the voltage comparator unit U1 and the clock input CLK of the fault latch unit U2; while the delay capacitor C3 is connected in parallel between the clock input CLK and the second terminal (i.e., circuit ground) of the sampling resistor R1. The delay resistor R6 and the delay capacitor C3 together form an RC integrator circuit or a low-pass filter. When the voltage comparator unit U1 outputs a high level, current flows through the delay resistor R6 to charge the delay capacitor C3, so that the voltage at the clock input CLK does not jump instantaneously, but rises slowly according to the rate determined by the RC time constant. Only when this voltage rises to the clock threshold of the fault latch unit U2 will the latching action be triggered. The time consumed by this charging process is the required critical delay, ensuring that the data can be stably latched.

[0064] In one example, the resistance of the delay resistor R6 is set to 1kΩ; the capacitance of the delay capacitor C3 is set to 1nF, and the time constant of the RC filter is 1µs.

[0065] In some embodiments, to ensure that each critical node in the circuit has a defined logic level, such as Figure 2 As shown, the short-circuit detection control circuit also includes pull-up resistor R5 and pull-down resistor R7. Pull-up resistor R5 is connected between the power supply and the output of voltage comparator unit U1. Its function is to cooperate with the open-collector (or open-drain) output structure inside voltage comparator unit U1, reliably pulling the output node high when voltage comparator unit U1 does not output a low level, thus providing a clear logic "1" signal for subsequent circuits. Pull-down resistor R7 is connected between the clock input terminal CLK of fault latch unit U2 and the second terminal (i.e., circuit ground) of sampling resistor R1. Its main function is to ensure that when the output of voltage comparator unit U1 is low, the clock input terminal CLK can be quickly and reliably pulled low, preventing the pin from being disturbed by noise and generating an incorrect trigger signal due to floating. It also provides a discharge path for delay capacitor C3.

[0066] In one example, the pull-up resistor R5 and the pull-down resistor R7 are set to 1kΩ; where the pull-down resistor R7 is at a low level when the first Schottky diode Q8 and the second Schottky diode Q9 have no output.

[0067] In some embodiments, an RC delay circuit is cleverly used to create data setup time for the D flip-flop, solving the technical challenge of reliably triggering its own latch using the same signal source. Simultaneously, the use of pull-up and pull-down resistors ensures signal quality and anti-interference capability throughout the entire logic chain. The synergistic operation of these three components enables this protection circuit to stably and reliably capture and lock even extremely short-circuit fault signals in a purely hardware-based manner until a clear reset command is received from the main control unit. This completely eliminates the safety risks associated with automatic system recovery after software crashes or transient faults, providing better safety assurance for the entire driver.

[0068] In some embodiments, to achieve software reset of the fault state and upload of fault information, such as Figure 2 As shown, the motor drive circuit includes a control unit U5 (MCU), and the short-circuit detection control circuit includes a first Schottky diode Q8 and a second Schottky diode Q9. Specifically, the input of the first Schottky diode Q8 is connected to an instruction interface (such as the RESET pin) of the control unit U5, and its output is connected to the first end of the delay resistor R6. Simultaneously, the input of the second Schottky diode Q9 is connected to the output of the voltage comparator unit U1, and its output is also connected to the first end of the delay resistor R6. These two diodes form an OR gate logic, meaning that both a fault signal detected by hardware (from the voltage comparator U1) and a reset command issued by software (from the control unit U5) can trigger the subsequent delay and latching circuits. Furthermore, the output Q of the fault latching unit U2 is also connected to a reporting interface (such as the FAULT_IN pin) of the control unit to report the current protection status to the control unit in real time. Schottky diodes are chosen here because of their extremely low forward voltage drop and extremely fast switching speed, ensuring efficient and interference-free signal transmission.

[0069] Reference Figure 3 This is a functional flowchart of a motor driver protection circuit provided in an embodiment of this application. Figure 3As shown in the diagram, the left-hand flow illustrates the triggering mechanism of the motor driver protection circuit: when a short circuit occurs in the motor drive circuit, the current flowing through the sampling resistor R1 increases sharply, causing the voltage across it to rise accordingly. The voltage comparison unit U1 monitors this voltage in real time, and once its value exceeds a preset threshold, the output of the voltage comparison unit U1 quickly flips to a high level. This high-level signal is sent to the data input D of the fault latch unit U2, enabling it to detect the high level; simultaneously, after a slight delay, a rising edge is formed at the clock input CLK of the fault latch unit U2. This crucial timing ensures that the fault latch unit U2 accurately latches the high-level fault signal at the data input D at the rising edge of the clock input CLK, thereby enabling the output Q to stably output a high-level signal. This latched high-level fault signal is transmitted to the cutoff control unit U4, causing it to disconnect the communication loop between the gate driver U3 and the tri-state buffer, thus shutting down the PWM output and cutting off the power loop within microseconds. Simultaneously, this signal is also detected by the control unit U5, indicating that the system has entered hardware protection mode.

[0070] The flowchart on the right describes the system's fault clearing and recovery logic: When the external short-circuit condition is physically eliminated, the current flowing through the sampling resistor R1 returns to normal, and the output of the voltage comparison unit U1 also returns to a low level, causing the data input terminal D of the fault latch unit U2 to detect a low level. However, due to the latching characteristics of the fault latch unit U2, its output terminal Q remains at a high level, and the system remains in a safe protection shutdown state and will not automatically recover. This effectively avoids secondary damage caused by repeated system restarts when the root cause of the fault is not identified. The recovery operation requires the active intervention of the control unit U5. That is, after confirming safety, the control unit U5 outputs a RESET high-level signal. This RESET signal will trigger the clock input terminal CLK of the fault latch unit U2 to detect a rising edge again. At this time, the fault latch unit U2 latches the low level (normal state) of the data input terminal D, causing its output terminal Q to flip to a low level. As the output terminal Q becomes low, the shutdown command of the cutoff control unit U4 is released, the PWM output is restarted, and the circuit returns to normal operation. Thus, the entire fault clearing process is completed.

[0071] This application constructs a pure hardware protection path that is completely independent of the main controller software through the above technical solution. When a short circuit occurs, the entire process from current sampling to comparison, latching, and finally cutting off the control signal is completed at the hardware level at a microsecond speed. Compared with the millisecond-level response of traditional fuses or digital protection schemes that rely on the MCU sampling cycle, this has an unparalleled speed advantage, ensuring effective circuit cutoff before the power switch is damaged due to exceeding its safe operating area. At the same time, the design of the fault latching unit ensures that even momentary short circuits can be reliably captured and maintained in a protected state, avoiding repeated impacts on the system while the fault is not cleared, thereby greatly improving the operational reliability, safety, and durability of the motor driver and its components.

[0072] Furthermore, embodiments of this application also provide a low-voltage motor driver. (Refer to...) Figure 4 This is a schematic diagram of a low-voltage motor driver provided in an embodiment of this application. A low-voltage motor driver is a complete functional module integrating power conversion, control logic, communication interface, and protection functions, typically represented as a printed circuit board (PCB). Figure 4 As shown, in addition to conventional components such as the motor, power interface, control unit (MCU), and power stage (three-phase inverter bridge and gate driver), the core components of this driver integrate and employ the aforementioned motor driver protection circuit. This gives the low-voltage motor driver itself extremely high safety, providing microsecond-level short-circuit protection at the factory, eliminating the need for users to design additional external protection. This greatly enhances the product's market competitiveness and user experience. Secondly, because the protection circuit and drive circuit are systematically integrated and optimized during the design, layout, and wiring stages, compared to external protection solutions, it can better suppress electromagnetic interference and achieve a shorter signal path, thereby further improving the speed and reliability of protection response. Finally, this integrated design enables the entire low-voltage motor driver product to achieve self-protection when facing extreme conditions such as load short circuits and wiring errors, avoiding permanent damage to core power devices. This not only provides a solid safety foundation for terminal equipment (such as magnetic drive conveyors and small robots) but also reduces maintenance costs and downtime losses caused by unexpected failures for users.

[0073] The embodiments described in this application are for the purpose of more clearly illustrating the technical solutions of the embodiments of this application, and do not constitute a limitation on the technical solutions provided by the embodiments of this application. As those skilled in the art will know, with the evolution of technology and the emergence of new application scenarios, the technical solutions provided by the embodiments of this application are also applicable to similar technical problems.

[0074] It should also be understood that the various implementation methods provided in this utility model embodiment can be combined arbitrarily to achieve different technical effects.

[0075] The above is a detailed description of the preferred embodiments of the present utility model. However, the present utility model is not limited to the above embodiments. Those skilled in the art can make various equivalent modifications or substitutions without departing from the spirit of the present utility model. All such equivalent modifications or substitutions are included within the scope defined by the claims of the present utility model.

Claims

1. A motor driver protection circuit, characterized in that, include: A motor drive circuit, the motor drive circuit including a sampling unit connected in series in the power main circuit of the motor drive circuit, the sampling unit being used to collect the voltage signal of the power main circuit; A short-circuit detection control circuit, comprising a voltage comparison unit and a fault latching unit, wherein a first input terminal of the voltage comparison unit is connected to a first terminal of the sampling unit, a second input terminal of the voltage comparison unit is connected to a second terminal of the sampling unit, and an output terminal of the voltage comparison unit is connected to an input terminal of the fault latching unit; A cut-off control unit is connected in series in the control signal path of the motor drive circuit, and the input terminal of the cut-off control unit is connected to the output terminal of the fault latch unit. When a short circuit occurs in the motor drive circuit, the voltage comparison unit outputs a high-level signal based on the voltage signal of the main power circuit. The input terminal of the fault latch unit outputs a high-level signal after detecting the high-level signal. The input terminal of the cut-off control unit disconnects the control signal path of the motor drive circuit after detecting the high-level signal.

2. The motor driver protection circuit according to claim 1, characterized in that, The sampling unit is a sampling resistor, which is connected in series between the power lower bridge arm and the power supply in the motor drive circuit.

3. The motor driver protection circuit according to claim 2, characterized in that, The short-circuit detection and control circuit is equipped with a filter resistor and a filter capacitor; The first end of the filter resistor is connected to the first end of the sampling resistor, and the second end of the filter resistor is connected to the first input end of the voltage comparison unit. The first end of the filter capacitor is connected to the second end of the filter resistor, and the second end of the filter capacitor is connected to the second end of the sampling resistor.

4. The motor driver protection circuit according to claim 3, characterized in that, The short-circuit detection control circuit is provided with a first voltage divider threshold resistor and a second voltage divider threshold resistor. The first end of the first voltage divider threshold resistor is connected to the second end of the sampling resistor, and the second end of the first voltage divider threshold resistor is connected to the second input end of the voltage comparison unit. The first end of the second voltage divider threshold resistor is connected to the power supply, and the second end of the second voltage divider threshold resistor is connected to the second input end of the voltage comparison unit.

5. The motor driver protection circuit according to claim 3, characterized in that, The short-circuit detection control circuit is further provided with a TVS diode, the first end of which is connected to the second end of the filter resistor, and the second end of the TVS diode is connected to the second end of the sampling resistor.

6. The motor driver protection circuit according to claim 2, characterized in that, The input terminals of the fault latch unit include a data input terminal and a clock input terminal, and the output terminal of the voltage comparison unit is connected to the data input terminal of the fault latch unit. The short-circuit detection control circuit includes a delay circuit. The output terminal of the voltage comparison unit is connected to the first terminal of the delay circuit, and the second terminal of the delay circuit is connected to the clock input terminal of the fault latch unit.

7. The motor driver protection circuit according to claim 6, characterized in that, The delay circuit includes a delay resistor and a delay capacitor; The first end of the delay resistor is connected to the output terminal of the voltage comparison unit, and the second end of the delay resistor is connected to the clock input terminal of the fault latch unit. The first end of the delay capacitor is connected to the second end of the sampling resistor, and the second end of the delay capacitor is connected to the clock input of the fault latch unit.

8. The motor driver protection circuit according to claim 7, characterized in that, The short-circuit detection control circuit includes a pull-up resistor and a pull-down resistor; The first end of the pull-up resistor is connected to the power supply, and the second end of the pull-up resistor is connected to the output end of the voltage comparison unit. The first end of the pull-down resistor is connected to the second end of the sampling resistor, and the second end of the pull-down resistor is connected to the clock input of the fault latch unit.

9. The motor driver protection circuit according to claim 8, characterized in that, The motor drive circuit includes a control unit, and the short-circuit detection control circuit includes a first Schottky diode and a second Schottky diode; The input terminal of the first Schottky diode is connected to the command interface of the control unit, and the output terminal of the first Schottky diode is connected to the first terminal of the delay resistor. The input terminal of the second Schottky diode is connected to the output terminal of the voltage comparator unit, and the output terminal of the second Schottky diode is connected to the first terminal of the delay resistor; The output of the fault latch unit is also connected to the reporting interface of the control unit.

10. The motor driver protection circuit according to claim 1, characterized in that, The motor drive circuit includes a control unit and a gate driver. The cut-off control unit is a tri-state buffer, which is connected in series on the pulse width modulation signal path between the control unit and the gate driver.

11. A low-voltage motor driver, characterized in that, Includes the motor driver protection circuit as described in any one of claims 1 to 10.

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