Motor driving circuit suitable for functional safety ASILB
By introducing a system base chip and controller MCU into the motor drive circuit, combined with components such as H-bridge pre-driver and H-bridge drive module, the problem that motor drive circuits in cost-sensitive applications cannot meet functional safety ASILB is solved, and the stability and fault tolerance are improved.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- 领科汇智科技有限公司
- Filing Date
- 2025-04-09
- Publication Date
- 2026-04-24
AI Technical Summary
Using high-level safety chips in cost-sensitive applications would significantly increase system costs for existing motor drive circuits, while also making it difficult to meet the functional safety ASILB requirements.
By employing H-bridge pre-drivers and H-bridge drive modules based on system base chips and controller MCUs, combined with components such as transistors, NMOS transistors, resistors, and limp-home modules, a functional safety ASILB motor drive circuit is constructed to achieve precise control and fault protection of the motor.
This achieves cost reduction while meeting the functional safety ASIL B requirements, improves system stability and fault tolerance, and ensures that the motor can still operate safely in the event of a fault.
Smart Images
Figure CN224164791U_ABST
Abstract
Description
Technical Field
[0001] This application relates to the technical field of motor drives, and in particular to a motor drive circuit suitable for functional safety ASILB. Background Technology
[0002] Motor drive circuits are widely used in various mechanical equipment, especially in the automotive and industrial automation fields. With technological advancements, motor drive circuits not only need to possess high efficiency and stability, but also must meet increasingly stringent reliability requirements, particularly in critical applications involving personal safety. Functional safety has become an indispensable part of modern motor drive circuits; ensuring that malfunctions do not lead to dangerous situations is of paramount importance.
[0003] Traditional motor drive circuit designs typically employ integrated solutions, directly selecting driver chips that meet ASIL B requirements. These chips incorporate safety mechanisms such as fault detection, overcurrent protection, and short-circuit protection, independently meeting functional safety requirements, thereby simplifying system design and reducing certification complexity.
[0004] However, the aforementioned existing technologies have certain limitations. In particular, for cost-sensitive applications, using high-level security chips can significantly increase the overall cost of the system. Utility Model Content
[0005] In order to reduce costs while ensuring that the motor drive circuit of QM meets the functional safety ASILB requirements, this application provides a motor drive circuit suitable for functional safety ASILB.
[0006] This application provides a technical solution for a functionally safe ASIL B motor drive circuit, which adopts the following approach:
[0007] A functional safety ASIL B motor drive circuit, based on a system base chip and a controller MCU, includes an H-bridge pre-driver and an H-bridge drive module. The H-bridge drive module is controlled and connected to the H-bridge pre-driver, which is controlled and connected to the controller MCU. The output terminal of the H-bridge drive module is electrically connected to the connection terminal of the motor. It also includes transistors Q5 and Q6. The base of transistor Q5 is electrically connected to the first output terminal of the controller MCU, and the base of transistor Q6 is electrically connected to the second output terminal of the controller MCU. The collector of transistor Q5 is electrically connected to the first control terminal of the H-bridge drive module, and the collector of transistor Q6 is electrically connected to the second control terminal of the H-bridge drive module. The emitters of both transistors Q5 and Q6 are grounded.
[0008] By adopting the above technical solution, the controller MCU can effectively control the H-bridge drive module through transistors Q5 and Q6, thereby achieving precise control of the motor drive. This lays the foundation for the entire motor drive circuit suitable for functional safety ASIL B, standardizes the connection methods of each major component, helps to achieve system stability and reliability, and meets the requirements of functional safety ASIL B.
[0009] Preferably, the H-bridge driver module includes NMOS transistors Q1, Q2, Q3, and Q4; the gates of NMOS transistors Q1, Q2, Q3, and Q4 are electrically connected to multiple output terminals of the H-bridge pre-driver, the voltage input terminal Vin is electrically connected to the drains of NMOS transistors Q1 and Q2, the source of NMOS transistor Q1 is electrically connected to the drain of NMOS transistor Q3, the source of NMOS transistor Q2 is electrically connected to the drain of NMOS transistor Q4, and the sources of NMOS transistors Q3 and Q4 are both grounded through resistor R1; the source of NMOS transistor Q2 is electrically connected to the positive terminal of the motor, and the source of NMOS transistor Q1 is electrically connected to the negative terminal of the motor; the gate of NMOS transistor Q3 is set as the first control terminal of the H-bridge driver module, and the gate of NMOS transistor Q4 is set as the second control terminal of the H-bridge driver module.
[0010] By adopting the above technical solution and through specific connection methods, such as connecting the voltage input terminal Vin to the drain of NMOS transistors Q1 and Q2, and the electrical connection between the sources of each NMOS transistor, a stable drive current is provided for the motor, ensuring that the motor can operate normally.
[0011] Preferably, resistors R2 and R4 are also included. The negative terminal of the motor is electrically connected to one end of resistor R2, and the positive terminal of the motor is electrically connected to one end of resistor R4. The other ends of resistors R2 and R4 are both grounded through resistor R4, and the connection point between resistors R2 and R3 is electrically connected to the second input terminal of the controller MCU.
[0012] By adopting the above technical solution, the voltage at both ends of the motor can be monitored and fed back. The controller MCU obtains the voltage signal at this connection point through the second input terminal, thereby understanding the operating status of the motor, such as whether the motor is operating normally, and whether there is overvoltage or undervoltage, which helps to achieve motor protection and precise control. Among them, resistor R3 is a pull-down resistor to ensure that the second input terminal of the controller MCU remains at a low level when there is no signal input, avoiding false triggering or instability caused by floating state.
[0013] Preferably, the two ends of resistor R1 are electrically connected to the two input terminals of the built-in amplifier of the H-bridge driver, and the output terminal of the built-in amplifier is electrically connected to the first input terminal of the controller MCU. By adopting the above technical solution, the signal is amplified by the built-in amplifier of the H-bridge driver, enabling the controller MCU to monitor the current in the motor circuit in real time. When abnormal current occurs, such as overcurrent or short circuit, the controller MCU can take corresponding protective measures in a timely manner, such as cutting off the power supply or adjusting the drive signal, thereby improving the safety and reliability of the system and protecting the motor and other circuit components from damage.
[0014] Preferably, the system also includes a limp home module, which includes an NPN transistor Q8, a PNP transistor Q9, and a PNP transistor Q9. The power supply terminal of the controller MCU is electrically connected to the collector of the NPN transistor Q8, the base of the NPN transistor Q8 is electrically connected to the output terminal of the system base chip, the emitter of the NPN transistor Q8 is electrically connected to the emitter of the PNP transistor Q9, the base of the PNP transistor Q9 is grounded, and the collector of the PNP transistor Q9 is electrically connected to the input terminal of the controller MCU.
[0015] By adopting the above technical solution, a limp home module is introduced. This module consists of an NPN transistor Q8 and a PNP transistor Q9. The system base chip controls the conduction and cutoff of the NPN transistor Q8, thereby affecting the working state of the PNP transistor Q9, and finally transmitting the signal to the input terminal of the controller MCU.
[0016] The limp home module plays a crucial role in system failures. It can ensure that the motor drive circuit can maintain basic operational capabilities to a certain extent even when some functions fail, allowing the equipment to continue operating in a limited but usable mode. For example, in certain fault situations, the vehicle can slowly drive to a safe location, improving the system's fault tolerance and user safety.
[0017] Preferably, the device also includes a PMOS transistor Q7, the gate of which is grounded, the source of which is electrically connected to the drain of the NMOS transistors Q1 and Q2, and the drain of which is electrically connected to the voltage input terminal Vin.
[0018] By adopting the above technical solution, this design can play a certain role in protection and voltage stabilization.
[0019] PMOS transistor Q7 can regulate and stabilize the voltage in the circuit, preventing voltage fluctuations from damaging the NMOS transistors in the H-bridge driver module. It also helps improve the anti-interference capability of the entire circuit and ensures the stable operation of the motor drive circuit.
[0020] Preferably, the system base chip also includes a low-dropout regulator, with the power input terminal Vin+ electrically connected to the input terminal of the low-dropout regulator, and the output terminal of the low-dropout regulator electrically connected to the power supply terminal of the controller MCU.
[0021] By adopting the above technical solution, the function of LDO is to stabilize the input power supply voltage at a suitable level, thereby providing a stable power supply to the controller MCU.
[0022] In summary, this application includes at least one of the following beneficial technical effects:
[0023] 1. By controlling the H-bridge pre-driver, transistor Q5, and transistor Q6 through the controller MCU, the forward and reverse rotation control of the motor and the rapid shutdown in the safety mechanism mode are realized. This ensures that the motor can be stopped quickly in the event of a fault, improves the functional safety of the system, and meets the requirements of ASILB level.
[0024] 2. By using resistor R1 and multiple resistors electrically connected to the motor and their connection methods, effective monitoring of the motor circuit current and voltage is achieved, further enhancing the reliability and stability of the system;
[0025] 3. A limp home module was introduced, which enables the controller MCU to continue performing necessary safety operations when the system fails, namely turning off transistors Q5 and Q6, thereby improving the system's fault tolerance and user experience. Attached Figure Description
[0026] Figure 1 This is a circuit diagram of an embodiment of this application.
[0027] Reference numerals: 1. H-bridge driver module; 2. Limp home module. Detailed Implementation
[0028] The following is in conjunction with the appendix Figure 1 This application will be described in further detail.
[0029] This application discloses a drive circuit for a functionally safe ASILB motor.
[0030] Reference Figure 1 A functional safety ASILB motor drive circuit includes a motor drive based on a controller MCUMUC and a system base chip SBC, including an H-bridge pre-driver and an H-bridge drive module 1. Multiple output terminals of the H-bridge pre-driver are electrically connected to multiple control terminals of the H-bridge drive module 1, and the output terminal of the H-bridge drive module 1 is electrically connected to the connection terminal of the motor.
[0031] The H-bridge driver module 1 includes NMOS transistors Q1, Q2, Q3, and Q4, and in this embodiment, it also includes a voltage input terminal Vin. The gates of NMOS transistors Q1, Q2, Q3, and Q4 are electrically connected to multiple output terminals of the H-bridge pre-driver. The voltage input terminal Vin is electrically connected to the drains of NMOS transistors Q1 and Q2. The source of NMOS transistor Q1 is electrically connected to the drain of NMOS transistor Q3, and the source of NMOS transistor Q2 is electrically connected to the drain of NMOS transistor Q4. The sources of NMOS transistors Q3 and Q4 are both grounded through resistor R1. The source of NMOS transistor Q2 is electrically connected to the positive terminal of the motor, and the source of NMOS transistor Q1 is electrically connected to the negative terminal of the motor. When the motor needs to be driven, the controller MCU controls the H-bridge pre-driver to turn on NMOS transistors Q1 and Q3, or NMOS transistors Q2 and Q4, thereby enabling forward and reverse rotation of the motor. In this configuration, the source of NMOS transistor Q3 is set as the first control terminal of H-bridge driver module 1, and the source of NMOS transistor Q4 is set as the second control terminal of H-bridge driver module 1.
[0032] Preferably, the embodiment of this application further includes a PMOS transistor Q7, the gate of which is grounded, the source of which is electrically connected to the drain of NMOS transistors Q1 and Q2, and the drain of which is electrically connected to the voltage input terminal Vin.
[0033] This application also includes transistors Q5 and Q6. The base of transistor Q5 is connected to the first output terminal of the controller MCU, and the base of transistor Q6 is connected to the second output terminal of the controller MCU. The collector of transistor Q5 is connected to the first control terminal of the H-bridge drive module 1, and the collector of transistor Q6 is connected to the second control terminal of the H-bridge drive module 1. The emitters of both transistors Q5 and Q6 are grounded. When the system needs to enter the safety mechanism mode, both the first and second output terminals of the controller MCU output a high level, thereby turning on transistors Q5 and Q6. At this time, the base voltages of NMOS transistors Q3 and Q4 are pulled low, turning off the H-bridge drive module 1, thus achieving the functional safety ASILB (unintended motor start) requirement.
[0034] Preferably, the two ends of resistor R1 are electrically connected to the two input terminals of the built-in amplifier of the H-bridge driver, and the output terminal of the built-in amplifier is electrically connected to the first input terminal of the controller MCU. The built-in amplifier amplifies the signal, thereby enabling monitoring of the motor circuit current. The negative terminal of the motor is grounded through resistors R2 and R3 in sequence, and the positive terminal is electrically connected to the connection point between resistors R2 and R3 through resistor R4. This connection point is also electrically connected to the second input terminal of the controller MCU, thereby enabling monitoring of the motor drive output voltage and effectively determining the motor drive output status.
[0035] This embodiment also includes a limp-home module 2, which includes an NPN transistor Q8 and a PNP transistor Q9. A diode D1 is electrically connected to the power input terminal Vin+. The anode of diode D1 is connected to the power input terminal Vin+, and the cathode of diode D1 is connected to the collector of NPN transistor Q8. The base of NPN transistor Q8 is connected to the output of the system base chip SBC. The emitter of NPN transistor Q8 is connected to the emitter of PNP transistor Q9. The base of PNP transistor Q9 is grounded, and the collector of PNP transistor Q9 is connected to the input of the controller MCU. When a system fault occurs, the output of the system base chip SBC outputs a high level. At this time, NPN transistor Q8 and PNP transistor Q9 conduct, allowing the output voltage of the power input terminal Vin+ to be input to the controller MCU. Then, the controller MCU drives transistors Q5 and Q6 to turn off the H-bridge driver module 1.
[0036] Building upon this, the system's base chip SBC also includes a low-dropout regulator (LDO). The cathode of diode D1 is electrically connected to the input terminal of the LDO, and the output terminal of the LDO is electrically connected to the power supply terminal of the controller MCU. By using the LDO, the output voltage can be kept stable even when the input voltage fluctuates significantly. This is crucial for ensuring the normal operation of the system's basic functions.
[0037] The implementation principle of a functional safety ASILB motor drive circuit in this application is as follows: After the product is powered on, the controller MCU first turns on transistors Q5 and Q6, and then the motor is turned on normally. The effectiveness of this safety mechanism and whether the MOS transistor under the H-bridge can be turned off normally are determined by the motor circuit current and output voltage. The output voltage monitoring can also determine whether the H-bridge transistor can be switched on and off normally. The use of low-cost transistors Q5 and Q6 compensates for the shortcomings of the QM chip; it better realizes hardware redundancy design and also reduces the resource usage of the MCU.
[0038] The above are all preferred embodiments of this application, and are not intended to limit the scope of protection of this application. Therefore, all equivalent changes made in accordance with the structure, shape and principle of this application should be covered within the scope of protection of this application.
Claims
1. A functional safety ASIL B motor drive circuit, based on a system base chip and a controller MCU, characterized in that: The device includes an H-bridge pre-driver and an H-bridge drive module (1). The H-bridge drive module (1) is controlled to be connected to the H-bridge pre-driver, and the H-bridge pre-driver is controlled to be connected to the controller MCU. The output terminal of the H-bridge drive module (1) is electrically connected to the connection terminal of the motor. The device also includes transistors Q5 and Q6. The base of transistor Q5 is electrically connected to the first output terminal of the controller MCU, the base of transistor Q6 is electrically connected to the second output terminal of the controller MCU, the collector of transistor Q5 is electrically connected to the first control terminal of the H-bridge drive module (1), and the collector of transistor Q6 is electrically connected to the second control terminal of the H-bridge drive module (1). The emitters of transistors Q5 and Q6 are both grounded.
2. A motor drive circuit suitable for functional safety ASIL B according to claim 1, characterized in that: The H-bridge driver module (1) includes NMOS transistors Q1, Q2, Q3, and Q4. The gates of NMOS transistors Q1, Q2, Q3, and Q4 are electrically connected to multiple output terminals of the H-bridge pre-driver, respectively. The voltage input terminal Vin is electrically connected to the drains of NMOS transistors Q1 and Q2. The source of NMOS transistor Q1 is electrically connected to the drain of NMOS transistor Q3, and the source of NMOS transistor Q2 is electrically connected to the drain of NMOS transistor Q4. The sources of NMOS transistors Q3 and Q4 are grounded through resistor R1. The source of NMOS transistor Q2 is electrically connected to the positive terminal of the motor, and the source of NMOS transistor Q1 is electrically connected to the negative terminal of the motor. The gate of NMOS transistor Q3 is set as the first control terminal of the H-bridge driver module, and the gate of NMOS transistor Q4 is set as the second control terminal of the H-bridge driver module.
3. A motor drive circuit suitable for functional safety ASIL B according to claim 1, characterized in that: It also includes resistors R2 and R4. The negative terminal of the motor is electrically connected to one end of resistor R2, and the positive terminal of the motor is electrically connected to one end of resistor R4. The other ends of resistors R2 and R4 are both grounded through resistor R4, and the connection point between resistors R2 and R3 is electrically connected to the second input terminal of the controller MCU.
4. A motor drive circuit suitable for functional safety ASIL B according to claim 2, characterized in that: The two ends of the resistor R1 are electrically connected to the two input terminals of the built-in amplifier of the H-bridge pre-driver, and the output terminal of the built-in amplifier of the H-bridge pre-driver is electrically connected to the first input terminal.
5. A motor drive circuit suitable for functional safety ASIL B according to claim 1 characterized in that: It also includes a limp home module (2), which includes an NPN transistor Q8 and a PNP transistor Q9. The power supply terminal of the controller MCU is electrically connected to the collector of the NPN transistor Q8, the base of the NPN transistor Q8 is electrically connected to the output terminal of the system base chip, the emitter of the NPN transistor Q8 is electrically connected to the emitter of the PNP transistor Q9, the base of the PNP transistor Q9 is grounded, and the collector of the PNP transistor Q9 is electrically connected to the input terminal of the controller MCU.
6. A motor drive circuit suitable for functional safety ASIL B according to claim 2, characterized in that: It also includes a PMOS transistor Q7, the gate of which is grounded, the source of which is electrically connected to the drain of the NMOS transistors Q1 and Q2, and the drain of which is electrically connected to the voltage input terminal Vin.
7. A motor drive circuit suitable for functional safety ASIL B according to claim 1 characterized in that: The system base chip also includes a low-dropout regulator, with the power input terminal Vin+ electrically connected to the input terminal of the low-dropout regulator, and the output terminal of the low-dropout regulator electrically connected to the power supply terminal of the controller MCU.