Motor stalling protection driving circuit

Abstract

The invention discloses a motor locked-rotor protection driving circuit, which relates to the field of motor locked-rotor protection, and is characterized in that a first thermosensitive detection unit and a second thermosensitive detection unit are respectively connected between two output ends of a motor and a corresponding power switch unit in series; and the control module automatically pulls down the control end of the connected power switch unit to be below a cut-off threshold value during stalling, so that a corresponding current path is cut off, and automatic stalling protection is realized. Although the scheme is realized on the basis of discrete electronic elements, a current sampling resistor, a voltage comparator and a latch logic circuit which are necessary in a traditional discrete scheme are omitted through a thermal-electric direct linkage mechanism, and self-triggering protection can be completed only through few devices such as a thermistor, a bipolar transistor and a bias resistor; according to the invention, customization limitation of a special driving chip is avoided, defects of large size, high cost and low reliability of a traditional discrete circuit are overcome, a topological structure is obviously simplified, and system cost, size and failure rate are reduced.

Description

Technical Field

[0001] This invention relates to the field of motor stall protection, and more particularly to a motor stall protection drive circuit. Background Technology

[0002] Electric folding rearview mirrors are an important comfort and safety feature in modern cars. Driven by an onboard motor, the mirrors automatically fold and unfold, making them widely used in scenarios such as passing oncoming vehicles in narrow roads and parking in underground garages. This effectively reduces the vehicle's lateral width and prevents the mirrors from scratching. At the same time, folding the mirrors in severe weather such as heavy rain and snow can also reduce the corrosive effects of the external environment on the mirrors and internal adjustment mechanisms, extending their service life.

[0003] Currently, stall protection solutions for rearview mirror folding drive systems mainly fall into two categories: one uses discrete components to build the control circuit, which offers some flexibility but suffers from large circuit size, numerous components, high cost, and low reliability. Furthermore, it often relies on additional latching or delay circuits for isolation protection after stalling, making the design complex. The other category uses integrated drive chip solutions, which offer high integration and a simpler peripheral circuitry, but their protection mechanisms are typically fixed thresholds or timed shutdowns, lacking dynamic sensing capabilities for the actual stall state. If the control signal is not removed promptly after the rearview mirror is folded into place, the motor will enter a stall state due to continuous power supply, leading to increased temperature rise and energy consumption. Long-term operation may even cause motor winding burnout or transmission mechanism jamming, affecting product lifespan and user experience.

[0004] Therefore, there is an urgent need for a stall protection drive circuit that is simple in structure, low in cost, and has accurate response. It should be able to sense the stall status in real time and automatically cut off the drive current when the rotor is folded into place or jammed due to obstruction, so as to achieve reliable shutdown and electrical isolation. At the same time, it should take into account miniaturization and high reliability to meet the comprehensive requirements of automotive electronics for safety, durability and cost control. Summary of the Invention

[0005] To address the issues of large size, high cost, or lack of precise stall protection in existing rearview mirror folding drive circuits, this invention proposes a motor stall protection drive circuit, comprising: The bidirectional motor main circuit includes a first power switch unit and a second power switch unit, which are used to control the on / off of the current path for the forward and reverse rotation of the motor, respectively. The temperature sensing module includes a first thermistor detection unit and a second thermistor detection unit. The first thermistor detection unit is connected in series between the first output terminal of the motor and the first power switch unit, and the second thermistor detection unit is connected in series between the second output terminal of the motor and the second power switch unit. The control module includes a first control unit and a second control unit. The detection terminal of the first control unit is connected to the voltage node of the first thermistor detection unit, and the control output terminal is connected to the control terminal of the first power switch unit. The detection terminal of the second control unit is connected to the voltage node of the second thermistor detection unit, and the control output terminal is connected to the control terminal of the second power switch unit. The first or second power switch unit is turned on when the motor is running normally; when the motor is stalled, the impedance of the corresponding thermal detection unit increases, triggering its corresponding control unit to pull down the control terminal of the connected power switch unit below the cutoff threshold, so as to cut off the corresponding current path and realize automatic stop protection.

[0006] Furthermore, the bidirectional motor main circuit also includes a first input terminal IN1 and a second input terminal IN2; The first input terminal IN1 is connected to the first power switch unit in sequence through the first rectifier diode D1, the second output terminal OUT2 of the motor, the motor winding, the first output terminal OUT1 of the motor, and the first thermal detection unit PTC1; The second input terminal IN2 is connected to the second power switch unit in sequence through the second rectifier diode D2, the first output terminal OUT1 of the motor, the motor winding, the second output terminal OUT2 of the motor, and the second thermal detection unit PTC2.

[0007] Furthermore, in the forward rotation mode of the motor, the first input terminal IN1 receives a high-level signal and the second input terminal IN2 receives a low-level signal; in the reverse rotation mode of the motor, the first input terminal IN1 receives a low-level signal and the second input terminal IN2 receives a high-level signal; the low-level signal is the circuit reference ground potential.

[0008] Furthermore, the first power switching unit includes a first NMOS transistor composed of a first drain D1, a first source S1 and a first gate G1; The first drain D1 of the first NMOS transistor is connected to one end of the first thermistor detection unit, the first source S1 is connected to the second input terminal IN2, and the first gate G1 constitutes the control terminal of the first power switch unit and is connected to the control output terminal of the first control unit.

[0009] Furthermore, the second power switching unit includes a second NMOS transistor composed of a second drain D2, a second source S2 and a second gate G2; The second drain D2 of the second NMOS transistor is connected to one end of the second thermistor detection unit, the second source S2 is connected to the first input terminal IN1, and the second gate G2 constitutes the control terminal of the second power switch unit, which is connected to the control output terminal of the second control unit.

[0010] Furthermore, the first control unit includes a first NPN transistor Q1 and a first bias resistor R1; The connection node between the first bias resistor R1 and the base of the first NPN transistor Q1 constitutes the detection terminal of the first control unit; The collector of the first NPN transistor Q1 constitutes the control output terminal of the first control unit; One end of the first bias resistor R1 is connected to the voltage node between the first thermistor detection unit PTC1 and the first output terminal OUT1 of the motor, and the other end is connected to the base of the first NPN transistor. The collector of the first NPN transistor is connected to the first gate G1 of the first NMOS transistor in the first power switching unit; The emitter of the first NPN transistor is connected to the first input terminal IN1.

[0011] Furthermore, the second control unit includes a second NPN transistor Q2 and a second bias resistor R2; The connection node between the second bias resistor R2 and the base of the second NPN transistor Q2 constitutes the detection terminal of the second control unit; The collector of the second NPN transistor Q2 constitutes the control output terminal of the second control unit; One end of the second bias resistor R2 is connected to the voltage node between the second thermistor detection unit PTC2 and the second output terminal OUT2 of the motor, and the other end is connected to the base of the second NPN transistor Q2; The collector of the second NPN transistor Q2 is connected to the second gate G2 of the second NMOS transistor in the second power switching unit; The emitter of the second NPN transistor Q2 is connected to the second input terminal IN2.

[0012] Furthermore, when the motor is in forward rotation and stalled, the impedance of the first thermistor PTC1 increases, the potential of the first output terminal OUT1 of the motor rises, the voltage at the connection node between the first bias resistor R1 and the base of the first NPN transistor Q1 rises, causing the first NPN transistor Q1 to conduct. The first gate G1 of the first NMOS transistor in the first power switch unit is pulled down to below the cutoff threshold, and the first NMOS transistor is turned off, thereby cutting off the current path between the first input terminal IN1 and the second input terminal IN2.

[0013] Furthermore, when the motor reverses and stalls, the impedance of the second thermistor PTC2 increases, the potential of the second output terminal OUT2 of the motor rises, and the voltage at the connection node between the second bias resistor R2 and the base of the second NPN transistor Q2 rises, causing the second NPN transistor Q2 to conduct. The second gate G2 of the second NMOS transistor in the second power switch unit is pulled down below the cutoff threshold, and the second NMOS transistor is turned off, thereby cutting off the current path between the second input terminal IN2 and the first input terminal IN1.

[0014] Furthermore, the first power switch unit and the second power switch unit are integrated into the same dual-channel NMOS power switch chip U1.

[0015] Compared with the prior art, the present invention has at least the following beneficial effects: (1) This invention connects the first and second thermistor detection units in series between the two output terminals of the motor and the corresponding power switch units. When the motor is stalled, the control module automatically pulls down the control terminal of the connected power switch unit to below the cutoff threshold, thereby cutting off the corresponding current path and achieving automatic stop protection. Although this scheme is based on discrete electronic components, it eliminates the current sampling resistor, voltage comparator and latching logic circuit required in traditional discrete schemes through the direct thermoelectric linkage mechanism. Only a few components such as thermistors, bipolar transistors and bias resistors are needed to complete the self-triggered protection. This not only avoids the customization limitations of dedicated driver chips, but also overcomes the defects of traditional discrete circuits such as large size, high cost and low reliability. It significantly simplifies the topology and reduces system cost, size and failure rate.

[0016] (2) The protection mechanism of this invention is directly related to the actual temperature rise state of the motor windings: when the motor stalls due to mechanical jamming or running to the limit position, the continuous current causes local heating, which causes the impedance of the corresponding thermal detection unit to rise nonlinearly, thereby raising the node voltage between it and the motor output terminal; this voltage change is directly sensed by the control unit and triggered to conduct, realizing a physical-level response to the stall event. Since the protection action depends on the actual heat accumulation process, rather than a preset current threshold or fixed delay, it can effectively distinguish between normal start-up surges, load fluctuations and actual stall conditions, fundamentally avoiding the false triggering or protection lag problems of traditional solutions, and significantly improving the reliability and robustness of the system in complex vehicle environments.

[0017] (3) This invention adopts a symmetrical dual-channel design: the forward and reverse paths are each equipped with an independent thermal detection unit, control unit, and power switch unit. When the rearview mirror is obstructed in either the folding or unfolding direction to its limit position (such as when the mirror is fully folded or unfolded), only the thermal detection unit in the corresponding direction is triggered for protection due to local temperature rise, shutting off the current path in that direction, while the circuit in the other direction remains in standby mode. This bidirectional independent protection mechanism ensures that precise and timely current cutoff can be achieved regardless of whether the mirror is stalled in either the forward or reverse direction, completely eliminating the risk of ineffective power consumption, winding overheating, or even insulation aging caused by the motor being continuously powered after folding, while retaining complete driving capability for subsequent reverse operation.

[0018] (4) The entire protection function of this invention is completed autonomously by pure hardware circuit without the need for microcontroller, dedicated driver chip or software algorithm. It not only has fast response speed and strong anti-interference ability, but also has fewer components and high integration. It is particularly suitable for vehicle application scenarios such as folding rearview mirrors, which have strict requirements for reliability, cost and space. It effectively balances safety, durability and mass production economy. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of a motor stall protection drive circuit according to an embodiment of the present invention. Detailed Implementation

[0020] The following are specific embodiments of the present invention, which are described in conjunction with the accompanying drawings. However, the present invention is not limited to these embodiments.

[0021] Example 1 To address the issues of large size, high cost, or lack of precise stall protection in existing rearview mirror folding drive circuits, such as... Figure 1 As shown, this invention proposes a motor stall protection drive circuit, comprising: The bidirectional motor main circuit includes a first power switch unit and a second power switch unit, which are used to control the on / off of the current path for the forward and reverse rotation of the motor, respectively. The first power switch unit and the second power switch unit are integrated into the same dual-channel NMOS power switch chip U1.

[0022] The bidirectional motor main circuit also includes a first input terminal IN1 and a second input terminal IN2; The first input terminal IN1 is connected to the first power switch unit in sequence through the first rectifier diode D1, the second output terminal OUT2 of the motor, the motor winding, the first output terminal OUT1 of the motor, and the first thermal detection unit PTC1; The first power switching unit includes a first NMOS transistor composed of a first drain D1, a first source S1 and a first gate G1; The first drain D1 of the first NMOS transistor is connected to one end of the first thermistor detection unit, the first source S1 is connected to the second input terminal IN2, and the first gate G1 constitutes the control terminal of the first power switch unit and is connected to the control output terminal of the first control unit.

[0023] The second input terminal IN2 is connected to the second power switch unit in sequence through the second rectifier diode D2, the first output terminal OUT1 of the motor, the motor winding, the second output terminal OUT2 of the motor, and the second thermal detection unit PTC2.

[0024] The second power switching unit includes a second NMOS transistor composed of a second drain D2, a second source S2 and a second gate G2; The second drain D2 of the second NMOS transistor is connected to one end of the second thermistor detection unit, the second source S2 is connected to the first input terminal IN1, and the second gate G2 constitutes the control terminal of the second power switch unit, which is connected to the control output terminal of the second control unit.

[0025] In this embodiment: The base of the first NPN transistor Q1 is connected in parallel with a second capacitor C2 and a fourth resistor R4 to suppress input signal noise. The collector of the first NPN transistor Q1 is connected in parallel with a second Zener diode ZD2 and a fourth capacitor C4 to absorb voltage spikes and improve circuit stability.

[0026] The base of the second NPN transistor Q2 is connected in parallel with a first capacitor C1 and a third resistor R3 to suppress input signal noise. The collector of the second NPN transistor Q2 is connected in parallel with a first Zener diode ZD1 and a third capacitor C3 to absorb voltage spikes and improve circuit stability.

[0027] A fifth resistor R5 is connected between the control terminal of the first power switch unit and the control terminal of the second power switch unit to prevent false triggering due to the control terminal of either power switch unit being left floating.

[0028] In the driving circuit of this invention, the control terminals (i.e., the gates of NMOS transistors) of the first and second power switching units are driven by the collectors of the corresponding NPN transistors. When a certain direction is not in operation (e.g., when the motor is rotating forward, the second NPN transistor Q2 in the second control unit is in the off state), its collector presents a high resistance state, causing the control terminal of the connected power switching unit (such as the second gate G2) to be in a floating state that is neither actively pulled up nor actively pulled down. Since the gate of the MOS transistor has extremely high input impedance, the floating control terminal is very easy to couple with external electromagnetic interference, static electricity, or residual charge from the previous conduction, causing its potential to drift randomly; once the potential accidentally rises above the conduction threshold of the power switching unit, even in the non-operating direction, it may cause the NMOS transistor to conduct unexpectedly, leading to logic confusion, protection failure, or abnormal switching transient current. To this end, this invention sets a fifth resistor R5 between the two control terminals to provide a discharge path for the floating gate, clamping its potential near a safe low level, thereby effectively suppressing false triggering caused by floating and ensuring the reliability and determinism of forward and reverse control.

[0029] In the forward rotation mode of the motor, the first input terminal IN1 receives a high-level signal and the second input terminal IN2 receives a low-level signal; in the reverse rotation mode of the motor, the first input terminal IN1 receives a low-level signal and the second input terminal IN2 receives a high-level signal; the low-level signal is the circuit reference ground potential.

[0030] This invention employs a symmetrical dual-channel design: the forward and reverse paths are each equipped with independent thermal detection units, control units, and power switching units. When the rearview mirror reaches its limit position (such as when the mirror is fully retracted or extended) in either the folding or unfolding direction and is obstructed, only the thermal detection unit in the corresponding direction is triggered for protection due to local temperature rise, shutting off the current path in that direction, while the circuit in the other direction remains in standby mode. This bidirectional independent protection mechanism ensures precise and timely current cutoff regardless of whether the mirror stalls in either the forward or reverse direction, completely eliminating the risk of ineffective power consumption, winding overheating, or even insulation aging caused by the motor continuously being powered after the mirror is fully folded, while preserving complete driving capability for subsequent reverse operation.

[0031] The temperature sensing module includes a first thermistor detection unit and a second thermistor detection unit. The first thermistor detection unit is connected in series between the first output terminal of the motor and the first power switch unit, and the second thermistor detection unit is connected in series between the second output terminal of the motor and the second power switch unit. The control module includes a first control unit and a second control unit. The detection terminal of the first control unit is connected to the voltage node of the first thermistor detection unit, and the control output terminal is connected to the control terminal of the first power switch unit. The detection terminal of the second control unit is connected to the voltage node of the second thermistor detection unit, and the control output terminal is connected to the control terminal of the second power switch unit. The first control unit includes a first NPN transistor Q1 and a first bias resistor R1; The connection node between the first bias resistor R1 and the base of the first NPN transistor Q1 constitutes the detection terminal of the first control unit; The collector of the first NPN transistor Q1 constitutes the control output terminal of the first control unit; One end of the first bias resistor R1 is connected to the voltage node between the first thermistor detection unit PTC1 and the first output terminal OUT1 of the motor, and the other end is connected to the base of the first NPN transistor. The collector of the first NPN transistor is connected to the first gate G1 of the first NMOS transistor in the first power switching unit; The emitter of the first NPN transistor is connected to the first input terminal IN1.

[0032] The second control unit includes a second NPN transistor Q2 and a second bias resistor R2; The connection node between the second bias resistor R2 and the base of the second NPN transistor Q2 constitutes the detection terminal of the second control unit; The collector of the second NPN transistor Q2 constitutes the control output terminal of the second control unit; One end of the second bias resistor R2 is connected to the voltage node between the second thermistor detection unit PTC2 and the second output terminal OUT2 of the motor, and the other end is connected to the base of the second NPN transistor Q2; The collector of the second NPN transistor Q2 is connected to the second gate G2 of the second NMOS transistor in the second power switching unit; The emitter of the second NPN transistor Q2 is connected to the second input terminal IN2.

[0033] The first or second power switch unit is turned on when the motor is running normally; when the motor is stalled, the impedance of the corresponding thermal detection unit increases, triggering its corresponding control unit to pull down the control terminal of the connected power switch unit below the cutoff threshold, so as to cut off the corresponding current path and realize automatic stop protection.

[0034] The protection mechanism of this invention is directly related to the actual temperature rise of the motor windings: when the motor stalls due to mechanical jamming or reaching its limit position, the continuous current causes localized heating, resulting in a nonlinear increase in the impedance of the corresponding thermistor detection unit, which in turn raises the node voltage between the thermistor and the motor output terminal. This voltage change is directly sensed by the control unit and triggered to conduct, achieving a physical-level response to the stall event. Since the protection action relies on the actual heat accumulation process, rather than a preset current threshold or fixed delay, it can effectively distinguish between normal starting surges, load fluctuations, and actual stall conditions, fundamentally avoiding the false triggering or protection lag problems of traditional solutions, and significantly improving the reliability and robustness of the system in complex vehicle environments.

[0035] When the motor is in forward rotation and stalled, the impedance of the first thermistor PTC1 increases, the potential of the first output terminal OUT1 of the motor rises, the voltage at the connection node between the first bias resistor R1 and the base of the first NPN transistor Q1 rises, causing the first NPN transistor Q1 to conduct. The first gate G1 of the first NMOS transistor in the first power switch unit is pulled down to below the cutoff threshold, and the first NMOS transistor is turned off, thereby cutting off the current path between the first input terminal IN1 and the second input terminal IN2.

[0036] Specifically: In the forward rotation mode of the motor, the current path is: first input terminal IN1 → first rectifier diode D1 → second output terminal OUT2 of the motor → motor winding → first output terminal OUT1 of the motor → first thermistor PTC1 → first NMOS transistor (its drain D1 is connected to the first thermistor PTC1, and its source S1 is connected to the second input terminal IN2) → second input terminal IN2.

[0037] When the motor stalls due to mechanical jamming or folding into place, the current flowing through the first thermistor PTC1 continues, causing the PTC1's temperature to rise and its impedance to increase significantly. This results in an increase in the voltage at the connection node between the first output terminal OUT1 and the PTC1. This voltage increase is transmitted to the base of the first NPN transistor Q1 through the first bias resistor R1, causing the voltage at the connection node between the first bias resistor R1 and the base of the first NPN transistor Q1 to rise. This creates a forward bias voltage between the base and emitter of the first NPN transistor Q1, causing the first NPN transistor Q1 to conduct. After the first NPN transistor Q1 conducts, its collector potential is pulled low. Since the collector is connected to the first gate G1 of the first NMOS transistor, the potential of the first gate G1 is pulled down to below the conduction threshold voltage of the first NMOS transistor, causing the first NMOS transistor to enter the cutoff state. This cuts off the forward current path between the first input terminal IN1 and the second input terminal IN2, achieving automatic stop protection.

[0038] When the motor reverses and stalls, the impedance of the second thermistor PTC2 increases, the potential of the second output terminal OUT2 of the motor rises, and the voltage at the connection node between the second bias resistor R2 and the base of the second NPN transistor Q2 rises, causing the second NPN transistor Q2 to conduct. The second gate G2 of the second NMOS transistor in the second power switch unit is pulled down below the cutoff threshold, and the second NMOS transistor is turned off, thereby cutting off the current path between the second input terminal IN2 and the first input terminal IN1.

[0039] Specifically: In motor reverse mode, the current path is: second input terminal IN2 → second rectifier diode D2 → first output terminal OUT1 of the motor → motor winding → second output terminal OUT2 of the motor → second thermistor detection unit PTC2 → second NMOS transistor (its drain D2 is connected to the second thermistor detection unit PTC2, and its source S2 is connected to the first input terminal IN1) → first input terminal IN1.

[0040] When the motor reverses and stalls due to mechanical jamming or being fully deployed, the current flowing through the second thermistor PTC2 continues, causing the PTC2's temperature to rise and its impedance to increase significantly. This results in an increase in the voltage at the connection point between the second output terminal OUT2 and PTC2. This voltage increase is transmitted to the base of the second NPN transistor Q2 through the second bias resistor R2, causing the voltage at the connection point between the second bias resistor R2 and the base of the second NPN transistor Q2 to rise. This creates a positive bias voltage between the base and emitter of the second NPN transistor Q2, causing it to turn on. After the second NPN transistor Q2 turns on, its collector potential is pulled low. Since this collector is connected to the second gate G2 of the second NMOS transistor, the potential of the second gate G2 is pulled down below the turn-on threshold voltage of the second NMOS transistor, causing the second NMOS transistor to enter the cut-off state. This cuts off the reverse current path between the second input terminal IN2 and the first input terminal IN1, achieving automatic stop protection.

[0041] This invention connects a first thermistor and a second thermistor in series between the two output terminals of the motor and the corresponding power switch unit. When the motor is stalled, the control module automatically pulls down the control terminal of the connected power switch unit to below the cutoff threshold, thereby cutting off the corresponding current path and achieving automatic shutdown protection. Although this solution is based on discrete electronic components, it eliminates the need for current sampling resistors, voltage comparators, and latching logic circuits required in traditional discrete solutions through a direct thermoelectric linkage mechanism. Self-triggered protection can be achieved with only a few components such as thermistors, bipolar transistors, and bias resistors. This not only avoids the customization limitations of dedicated driver chips but also overcomes the shortcomings of traditional discrete circuits, such as large size, high cost, and low reliability. It significantly simplifies the topology and reduces system cost, size, and failure rate.

[0042] Furthermore, the bidirectional stall-rotor self-protection drive system of this invention mainly consists of two PTC thermistors, two NPN transistors, two bias resistors, and a dual-channel NMOS power switch chip. The core protection logic does not rely on complex modules such as dedicated motor driver ICs, Hall sensors, ADC sampling, or MCU control. While ensuring high reliability, it greatly improves the circuit's robustness and environmental adaptability, making it particularly suitable for applications such as folding automotive rearview mirrors, which are space-constrained, cost-sensitive, and require long-term tolerance to harsh conditions such as vibration, high and low temperature cycling, and power fluctuations. In addition, since the protection action is directly triggered by analog hardware, the response speed is fast (millisecond-level) with no software delay. Combined with optional gate equalization resistors (such as R5), input filter capacitors, and Zener diodes, the system's electromagnetic interference resistance and long-term operational stability can be further enhanced, thereby comprehensively improving the circuit's safety and lifespan in automotive electronic environments.

[0043] It should be noted that all directional indications (such as up, down, left, right, front, back, etc.) in the embodiments of the present invention are only used to explain the relative positional relationship and movement of the components in a specific posture (as shown in the attached figures). If the specific posture changes, the directional indication will also change accordingly. Furthermore, descriptions involving "first," "second," or "a" in the present invention are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, features defined with "first" or "second" may explicitly or implicitly include at least one of those features. In the description of the present invention, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly defined. In the present invention, unless otherwise explicitly specified and defined, the terms "connection," "fixed," etc., should be interpreted broadly. For example, "fixed" can be a fixed connection, a detachable connection, or an integral part; 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 communication of two components or the interaction between two components, unless otherwise explicitly defined. For those skilled in the art, the specific meanings of the above terms in this invention can be understood according to the specific circumstances. Furthermore, the technical solutions of the various embodiments of this invention can be combined with each other, but only on the basis that those skilled in the art can implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection claimed by this invention.

Claims

1. A motor stall protection drive circuit, characterized in that, include: The bidirectional motor main circuit includes a first power switch unit and a second power switch unit, which are used to control the on / off of the current path for the forward and reverse rotation of the motor, respectively. The temperature sensing module includes a first thermistor detection unit and a second thermistor detection unit. The first thermistor detection unit is connected in series between the first output terminal of the motor and the first power switch unit, and the second thermistor detection unit is connected in series between the second output terminal of the motor and the second power switch unit. The control module includes a first control unit and a second control unit. The detection terminal of the first control unit is connected to the voltage node of the first thermistor detection unit, and the control output terminal is connected to the control terminal of the first power switch unit. The detection terminal of the second control unit is connected to the voltage node of the second thermistor detection unit, and the control output terminal is connected to the control terminal of the second power switch unit. The first or second power switch unit is turned on when the motor is running normally; when the motor is stalled, the impedance of the corresponding thermal detection unit increases, triggering its corresponding control unit to pull down the control terminal of the connected power switch unit below the cutoff threshold, so as to cut off the corresponding current path and realize automatic stop protection.

2. The motor stall protection drive circuit according to claim 1, characterized in that, The bidirectional motor main circuit also includes a first input terminal IN1 and a second input terminal IN2; The first input terminal IN1 is connected to the first power switch unit in sequence through the first rectifier diode D1, the second output terminal OUT2 of the motor, the motor winding, the first output terminal OUT1 of the motor, and the first thermal detection unit PTC1; The second input terminal IN2 is connected to the second power switch unit in sequence through the second rectifier diode D2, the first output terminal OUT1 of the motor, the motor winding, the second output terminal OUT2 of the motor, and the second thermal detection unit PTC2.

3. The motor stall protection drive circuit according to claim 2, characterized in that, In the forward rotation mode of the motor, the first input terminal IN1 receives a high-level signal and the second input terminal IN2 receives a low-level signal; in the reverse rotation mode of the motor, the first input terminal IN1 receives a low-level signal and the second input terminal IN2 receives a high-level signal; the low-level signal is the circuit reference ground potential.

4. The motor stall protection drive circuit according to claim 3, characterized in that, The first power switching unit includes a first NMOS transistor composed of a first drain D1, a first source S1 and a first gate G1; The first drain D1 of the first NMOS transistor is connected to one end of the first thermistor detection unit, the first source S1 is connected to the second input terminal IN2, and the first gate G1 constitutes the control terminal of the first power switch unit and is connected to the control output terminal of the first control unit.

5. A motor stall protection drive circuit according to claim 3, characterized in that, The second power switching unit includes a second NMOS transistor composed of a second drain D2, a second source S2 and a second gate G2; The second drain D2 of the second NMOS transistor is connected to one end of the second thermistor detection unit, the second source S2 is connected to the first input terminal IN1, and the second gate G2 constitutes the control terminal of the second power switch unit, which is connected to the control output terminal of the second control unit.

6. A motor stall protection drive circuit according to claim 4, characterized in that, The first control unit includes a first NPN transistor Q1 and a first bias resistor R1; The connection node between the first bias resistor R1 and the base of the first NPN transistor Q1 constitutes the detection terminal of the first control unit; The collector of the first NPN transistor Q1 constitutes the control output terminal of the first control unit; One end of the first bias resistor R1 is connected to the voltage node between the first thermistor detection unit PTC1 and the first output terminal OUT1 of the motor, and the other end is connected to the base of the first NPN transistor. The collector of the first NPN transistor is connected to the first gate G1 of the first NMOS transistor in the first power switching unit; The emitter of the first NPN transistor is connected to the first input terminal IN1.

7. The motor stall protection drive circuit according to claim 5, characterized in that, The second control unit includes a second NPN transistor Q2 and a second bias resistor R2; The connection node between the second bias resistor R2 and the base of the second NPN transistor Q2 constitutes the detection terminal of the second control unit; The collector of the second NPN transistor Q2 constitutes the control output terminal of the second control unit; One end of the second bias resistor R2 is connected to the voltage node between the second thermistor detection unit PTC2 and the second output terminal OUT2 of the motor, and the other end is connected to the base of the second NPN transistor Q2; The collector of the second NPN transistor Q2 is connected to the second gate G2 of the second NMOS transistor in the second power switching unit; The emitter of the second NPN transistor Q2 is connected to the second input terminal IN2.

8. A motor stall protection drive circuit according to claim 6, characterized in that, When the motor is in forward rotation and stalled, the impedance of the first thermistor PTC1 increases, the potential of the first output terminal OUT1 of the motor rises, the voltage at the connection node between the first bias resistor R1 and the base of the first NPN transistor Q1 rises, causing the first NPN transistor Q1 to conduct. The first gate G1 of the first NMOS transistor in the first power switch unit is pulled down to below the cutoff threshold, and the first NMOS transistor is turned off, thereby cutting off the current path between the first input terminal IN1 and the second input terminal IN2.

9. A motor stall protection drive circuit according to claim 7, characterized in that, When the motor reverses and stalls, the impedance of the second thermistor PTC2 increases, the potential of the second output terminal OUT2 of the motor rises, and the voltage at the connection node between the second bias resistor R2 and the base of the second NPN transistor Q2 rises, causing the second NPN transistor Q2 to conduct. The second gate G2 of the second NMOS transistor in the second power switch unit is pulled down below the cutoff threshold, and the second NMOS transistor is turned off, thereby cutting off the current path between the second input terminal IN2 and the first input terminal IN1.

10. A motor stall protection drive circuit according to claim 1, characterized in that, The first power switch unit and the second power switch unit are integrated into the same dual-channel NMOS power switch chip U1.

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