A brushless motor control chip adaptive speed regulation mechanism with over-temperature protection
Patent Information
- Application Number
- CN202610868252.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-06-16
- Publication Date
- 2026-08-18
AI Technical Summary
[0003]为降低风险，工业级控制器普遍要求具备过温保护，现有解决方案是在功率级附近布置温度传感器，通过温度感知到阈值判断，最后进行保护执行的链条，很多电机驱动芯片内部提供过温警告OTW和过温关断OTSD两级温度反应，在过温警告OTW状态下，通过系统侧MCU做出减载的动作以避免进一步走向热关断；在OTSD时将半桥置为高阻Hi-Z；过温保护处理方式停留在硬性停机以及仅依赖芯片内部热关断兜底的状态，无法适应性调节
本申请中，温度感知组件多个温度点位用于温差合理性校验，温度感知组件不同分压节点通过微控制器单元MCU的ADC通道进入控制回路，温度感知组件不同分压节点通过热预估模型补偿，微控制器单元MCU运行FOC正弦波控制换向或梯形波换向，其内部包括脉冲宽度调制PWM产生单元，微控制器单元MCU实现换向决策、PWM生成和保护仲裁的逻辑，在正确时刻给出正确的占空比，把温度作为约束条件之一参与决策，工作过程为，每个控制周期读入转速反馈、电流反馈和温度反馈，计算目标转矩电流、受限于热导出的限制电流，最后输出脉冲宽度调制PWM，硬件保护组件提供一个相对独立于主控固件的路径，温度感知组件采集的温度信号T直接与模拟比较器内置参考对比，模拟比较器输出接到三相半桥功率开关栅极驱动，温度越过阈值立即撤驱动，只负责别让器件结温冲穿，结构件都是无固件依赖的逻辑件，即使控制芯片组件死机仍能动作，补足软件通道的可用性短板。
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Figure CN122600846A_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of thermal management and speed control technology for brushless DC motor control systems, specifically to an adaptive speed control mechanism for a brushless motor control chip with over-temperature protection. Background Technology
[0002] Brushless motors are widely used in power tools, vacuum cleaners, small household appliances, and light electric vehicles. The power stage is usually composed of a three-phase half-bridge inverter structure. Under the scheduling of the microcontroller unit (MCU) or control core, the gate drive or integrated driver chip outputs PWM to complete trapezoidal wave commutation or FOC sine wave control. Speed regulation is achieved by adjusting the voltage or duty cycle. The device is small in size and has high power density. However, in a closed enclosure, with limited ventilation, high temperature environment, load fluctuation, or long-term full-load operation, the junction temperature of the power device, PCB hot spots, or winding temperature rise rapidly. Once the safe range is exceeded, failures such as performance degradation, parameter drift, gate drive failure, MOSFET thermal breakdown, winding insulation aging, or even burnout will occur.
[0003] To mitigate risks, industrial-grade controllers are generally required to have over-temperature protection. Existing solutions involve placing temperature sensors near the power stage, sensing temperature to determine a threshold, and then executing a protection mechanism. Many motor drive chips internally provide two levels of temperature response: Over-Temperature Warning (OTW) and Over-Temperature Shutdown (OTSD). In the OTW state, the system-side MCU reduces the load to prevent further thermal shutdown. In the OTSD state, the half-bridge is set to high impedance (Hi-Z). The over-temperature protection method remains at the level of hard shutdown and relies solely on the chip's internal thermal shutdown as a fallback, lacking adaptive adjustment.
[0004] Therefore, it is necessary to provide an adaptive speed regulation mechanism for a brushless motor control chip with over-temperature protection to solve the problems mentioned in the background art. Summary of the Invention
[0005] To achieve the above objectives, this application provides the following technical solution: an adaptive speed control mechanism for a brushless motor control chip with over-temperature protection, comprising a temperature sensing component, a control chip component, a hardware protection component, a speed control component, and a power stage component. Multiple temperature sensing components are arranged. The control chip component includes a current sampling path connected to and transmitting signals to the temperature sensing components, and a component that outputs a pulse width modulation (PWM) signal. The duty cycle of the PWM signal is controlled by the control chip component and then transmitted to a three-phase half-bridge power switch. The three-phase half-bridge power switch further controls the motor operation. Additionally, the temperature sensing components are connected to the hardware protection component, which includes an analog comparator connected to the three-phase half-bridge power switch to control the motor operation. The power stage component is powered by a power supply.
[0006] Furthermore, as a preferred embodiment, the temperature sensing components are located on the high and low sides of the three-phase bridge of the motor, the heat conduction path of the control chip components and the bottom pads of the motor, and the corresponding temperature signals collected are T1, T2 and T3 respectively.
[0007] Furthermore, as a preferred embodiment, the control chip assembly also includes a processor that receives the temperature signal T transmitted by the temperature sensing component and a thermal prediction model built into the control chip assembly.
[0008] Furthermore, as a preferred embodiment, the analog comparator has a built-in temperature reference, receives temperature signals T1, T2, and T3 transmitted by the temperature sensing component, compares them with the built-in temperature reference, and the analog comparator is connected to and outputs signals to the three-phase half-bridge power switch.
[0009] Furthermore, as a preferred embodiment, the speed control component includes a limiter, wherein multiple limiters are arranged, and the speed control component also includes a temperature-speed reduction mapping recorded in the control chip component.
[0010] Furthermore, as a preferred embodiment, the temperature-speed reduction mapping includes the maximum permissible output ratio K associated with the temperature signal T transmitted by the temperature sensing component.
[0011] Furthermore, as a preferred embodiment, the limiter functions as limiting the minimum permissible rotational speed, limiting the maximum permissible depth of drop, and limiting thermal speed.
[0012] Furthermore, as a preferred embodiment, the power stage components also include a gate drive power supply, a bootstrap capacitor, and a current sampling resistor. The three-phase half-bridge power switch is driven by the gate drive power supply and the bootstrap capacitor, and multiple current sampling resistors are arranged and set on the low side of the three-phase bridge of the motor.
[0013] Compared with the prior art, this application provides an adaptive speed regulation mechanism for a brushless motor control chip with over-temperature protection, which has the following advantages: In this application, multiple temperature points of the temperature sensing component are used for temperature difference rationality verification. Different voltage divider nodes of the temperature sensing component enter the control loop through the ADC channel of the microcontroller unit (MCU). Different voltage divider nodes of the temperature sensing component are compensated by a thermal prediction model. The MCU runs FOC sine wave control commutation or trapezoidal wave commutation. It includes a pulse width modulation (PWM) generation unit. The MCU implements the logic of commutation decision, PWM generation and protection arbitration, and provides the correct duty cycle at the correct time. Temperature is used as one of the constraints in the decision. The working process is as follows: each control cycle reads the speed feedback, current feedback and temperature feedback, calculates the target torque current and the limiting current limited by thermal output, and finally outputs the pulse width modulation (PWM). The hardware protection component provides a path that is relatively independent of the main control firmware. The temperature signal T collected by the temperature sensing component is directly compared with the built-in reference of the analog comparator. The output of the analog comparator is connected to the gate drive of the three-phase half-bridge power switch. The drive is immediately withdrawn when the temperature exceeds the threshold. It is only responsible for preventing the junction temperature of the device from breaking down. The structural components are all logic components without firmware dependence. Even if the control chip component crashes, it can still operate, making up for the usability shortcomings of the software channel. Attached Figure Description
[0014] Other features, objects, and advantages of this application will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings: Figure 1 This is a schematic diagram illustrating the working process of an adaptive speed control mechanism for a brushless motor control chip with over-temperature protection. Figure 2 This is a schematic diagram illustrating the working process of a control chip for an adaptive speed regulation mechanism of a brushless motor control chip with over-temperature protection. Figure 3 This is a schematic diagram of the software channel signal transmission for an adaptive speed control mechanism of a brushless motor control chip with over-temperature protection. Figure 4 This is a schematic diagram of the hardware channel signal transmission of an adaptive speed regulation mechanism for a brushless motor control chip with over-temperature protection. In the diagram: 1. Power supply; 2. Temperature sensing component; 3. Control chip component; 31. Current sampling path; 32. Pulse width modulation signal; 4. Hardware protection component; 41. Analog comparator; 5. Speed control component; 51. Temperature-speed reduction mapping; 52. Limiter; 6. Power stage component; 61. Three-phase half-bridge power switch; 62. Gate drive power supply; 63. Bootstrap capacitor; 64. Current sampling resistor; 7. Motor. Detailed Implementation
[0015] Please see Figures 1-4In this embodiment of the application, an adaptive speed control mechanism for a brushless motor control chip with over-temperature protection includes a temperature sensing component 2, a control chip component 3, a hardware protection component 4, a speed control component 5, and a power stage component 6. Multiple temperature sensing components 2 are arranged. The control chip component 3 includes a current sampling path 31 connected to and transmitting signals to the temperature sensing components 2, and a component that outputs a pulse width modulation signal 32. The duty cycle of the pulse width modulation signal 32 is controlled by the control chip component 3 and then transmitted to a three-phase half-bridge power switch 61. The three-phase half-bridge power switch 61 further controls the operation of the motor 7. Additionally, the temperature sensing components 2 are also connected to the hardware protection component 4, which includes an analog comparator 41. The analog comparator 41 is connected to the three-phase half-bridge power switch 61 to control the operation of the motor 7. The power stage component 6 is connected to a power supply 1.
[0016] It needs to be explained that the entire working process is divided into three levels: energy transmission chain, signal transmission chain, and control chain. The energy transmission chain transmits power from power supply 1 to the phase line of motor 7 through power stage component 6. The signal transmission chain is divided into two branches: a software channel and a hardware channel. The software channel transmits signals from temperature sensing component 2 to control chip component 3, and the hardware channel transmits signals from temperature sensing component 2 to hardware protection component 4. The control chain transmits the user-requested torque current I to control chip component 3 for processing, and adjusts the output pulse width modulation signal 32 to power stage component 6 to control the rotation of motor 7. The pulse width modulation signal 32 is also regulated by the signal transmission chain to achieve over-temperature control.
[0017] It should be explained that the control chip assembly 3 may also include an over-temperature warning (OTW). The OTW signal serves as a thermal warning interrupt in the control chip assembly 3 and, in more serious cases, sets the half-bridge to Hi-Z.
[0018] In a preferred embodiment, the temperature sensing component 2 is disposed on the high side and low side of the three-phase bridge of the motor 7, the heat conduction path of the control chip component 3 and the bottom pad of the motor 7, and the corresponding temperature signals collected are T1, T2 and T3 in sequence.
[0019] It should be explained that the temperature sensing component 2 can be a thermistor NTC. The physical location of the temperature sampling is arranged at the point that truly reflects the temperature of the hot spot. The high and low sides of the three-phase bridge of motor 7 are preferred. The heat conduction path of the control chip component 3 and the bottom pad of motor 7 is also considered. Multiple temperature points are used for temperature difference rationality verification. Surface mount thermistors NTC or leaded thermistors NTC with thermally conductive silicone are used to adapt to high-density layouts. During the pressing process, the heat conduction path is controlled to ensure that the thermistor NTC sensing surface takes the shortest thermal path between the main heat source, and the thermal contact surface is controlled to reduce the thermal resistance caused by air gaps and insulating sheets. During operation, the resistance of the thermistor NTC decreases monotonically with the increase of temperature, and the voltage at the voltage divider point changes accordingly. The control chip component 3 converts the voltage into temperature, that is, heat into a low-noise electrical signal, providing an input signal for subsequent speed adjustment.
[0020] In a preferred embodiment, the control chip assembly 3 further includes a processor that receives the temperature signal T transmitted by the temperature sensing component 2 and has a built-in thermal prediction model.
[0021] It should be explained that the control chip component 3 preferably uses a microcontroller unit (MCU). Different voltage divider nodes of the temperature sensing component 2 enter the control loop through the ADC channel of the MCU, and the signal path avoids parallel coupling with the gate drive high-current loop. Different voltage divider nodes of the temperature sensing component 2 are compensated by a thermal prediction model. The MCU runs FOC sine wave control commutation or trapezoidal wave commutation. It includes a pulse width modulation (PWM) generation unit. The MCU implements the logic of commutation decision, PWM generation and protection arbitration, and provides the correct duty cycle at the correct time. Temperature is used as one of the constraints in the decision. The working process is as follows: each control cycle reads the speed feedback, current feedback and temperature feedback, calculates the target torque current and the limiting current due to thermal exhaust, and finally outputs the pulse width modulation (PWM). The protection logic responds in stages from early warning to dynamic derating, based on the preset usage environment, such as intermittent high power use and continuous power use, and works in conjunction with temperature monitoring to ensure efficient over-temperature regulation and no loss of synchronization even with derating.
[0022] In a preferred embodiment, the analog comparator 41 has a built-in temperature reference, receives temperature signals T1, T2, and T3 transmitted by the temperature sensing component 2 and compares them with the built-in temperature reference, and the analog comparator 41 is connected to and outputs signals to the three-phase half-bridge power switch 61.
[0023] It needs to be explained that the hardware protection component 4 provides a path that is relatively independent of the main control firmware. The temperature signal T collected by the temperature sensing component 2 is directly compared with the built-in reference of the analog comparator 41. The output of the analog comparator 41 is connected to the gate drive of the three-phase half-bridge power switch 61. The drive is immediately withdrawn when the temperature exceeds the threshold. It is only responsible for preventing the junction temperature of the device from breaking through. The structural components are all logic components without firmware dependence. Even if the control chip component 3 crashes, it can still operate, making up for the shortcoming of the availability of the software channel.
[0024] In a preferred embodiment, the speed control component 5 includes a limiter 52, which is arranged in multiple ways, and the speed control component 5 also includes a temperature-speed reduction mapping 51 recorded in the control chip component 3.
[0025] In a preferred embodiment, the temperature-speed reduction mapping 51 includes the maximum permissible output ratio K associated with the temperature signal T transmitted by the temperature sensing component 2.
[0026] In a preferred embodiment, the limiter 52 functions as a minimum permissible rotational speed limiter, a maximum permissible drop depth limiter, and a thermal limiter.
[0027] It needs to be explained that after the temperature is read by the temperature sensing component 2, the temperature signal T collected by the temperature sensing component 2 is mapped to the maximum allowable output ratio K. The actual command is obtained by multiplying the user-requested torque current I by K. The pulse width modulation (PWM) duty cycle decreases as the temperature rises, thereby continuously reducing power and heat generation. When the temperature signal T collected by the temperature sensing component 2 drops and there is a hysteresis margin, K gradually rises to avoid sawtooth oscillation. At higher temperatures, it enters stronger restrictions or even power-off. The speed control component 5 is based on control theory. The speed control component 5 acts as a valve inserted between the user command and the output of the motor 7. The maximum output ratio K is the valve opening, which turns overheating from an accident into a manageable process, retaining some output, gaining cooling time, and avoiding hard shutdown impact. K is based on the limit of multi-point temperature and incorporates a thermal prediction model to achieve smoother feedforward derating. The hardware threshold K is slightly higher than the most severe limit that the software threshold K can reach, but still lower than the absolute maximum junction temperature, forming an orderly two-level ladder. The software is flexible first and the hardware is hard last, forming a dual-channel protection between software and hardware.
[0028] In a preferred embodiment, the power stage component 6 further includes a gate drive power supply 62, a bootstrap capacitor 63, and a current sampling resistor 64. The three-phase half-bridge power switch 61 is driven by the gate drive power supply 62 and the bootstrap capacitor 63, and multiple current sampling resistors 64 are arranged and set on the low side of the three-phase bridge of the motor 7.
[0029] It should be explained that the three-phase half-bridge power switch 61 uses MOSFET semiconductor field-effect transistors. In the control chain, the current sampling resistor 64 collects the signal and feeds it back to the control chip component 3. The power stage component 6 realizes the pulse width modulation (PWM) of the microcontroller unit MCU and outputs it successfully, while exposing the temperature risk to the sampling network and protection logic.
[0030] In specific implementation, multiple temperature points of temperature sensing component 2 are used for temperature difference rationality verification. Different voltage divider nodes of temperature sensing component 2 enter the control loop through the ADC channel of microcontroller unit (MCU). Different voltage divider nodes of temperature sensing component 2 are compensated by thermal prediction model. Microcontroller unit (MCU) runs FOC sine wave control commutation or trapezoidal wave commutation. It includes a pulse width modulation (PWM) generation unit. Microcontroller unit (MCU) implements the logic of commutation decision, PWM generation and protection arbitration, and provides the correct duty cycle at the correct time. Temperature is used as one of the constraints in the decision-making process. The working process is as follows: each control... The system reads speed feedback, current feedback, and temperature feedback during the control cycle, calculates the target torque current and the limiting current due to thermal exhaustion, and finally outputs pulse width modulation (PWM). The hardware protection component 4 provides a path relatively independent of the main control firmware. The temperature signal T collected by the temperature sensing component 2 is directly compared with the built-in reference of the analog comparator 41. The output of the analog comparator 41 is connected to the gate drive of the three-phase half-bridge power switch 61. The drive is immediately withdrawn when the temperature exceeds the threshold, and it is only responsible for preventing the junction temperature of the device from breaking down. The structural components are all logic components without firmware dependence. Even if the control chip component 3 crashes, it can still operate, making up for the usability shortcomings of the software channel.
[0031] The above description is merely a preferred embodiment of this application, but the scope of protection of this application is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in this application, based on the technical solution and application concept of this application, should be included within the scope of protection of this application.
Claims
1. An adaptive speed control mechanism for a brushless motor control chip with over-temperature protection, characterized in that: The system includes a temperature sensing component (2), a control chip component (3), a hardware protection component (4), a speed control component (5), and a power stage component (6). The temperature sensing component (2) is arranged in multiple parts. The control chip component (3) includes a current sampling path (31) connected to the temperature sensing component (2) and transmitting signals, as well as a component that outputs a pulse width modulation signal (32). The duty cycle of the pulse width modulation signal (32) is controlled by the control chip component (3) and then transmitted to the three-phase half-bridge power switch (61). The three-phase half-bridge power switch (61) further controls the operation of the motor (7). In addition, the temperature sensing component (2) is also connected to the hardware protection component (4). The hardware protection component (4) includes an analog comparator (41). The analog comparator (41) is connected to the three-phase half-bridge power switch (61) to control the operation of the motor (7). The power stage component (6) is connected to the power supply (1).
2. The adaptive speed regulation mechanism for a brushless motor control chip with over-temperature protection according to claim 1, characterized in that: The temperature sensing component (2) is set on the high side and low side of the three-phase bridge of the motor (7), the heat conduction path of the control chip component (3) and the bottom pad of the motor (7), and the corresponding temperature signals collected are T1, T2 and T3 in sequence.
3. The adaptive speed control mechanism for a brushless motor control chip with over-temperature protection according to claim 1, characterized in that: The control chip assembly (3) also includes a processor that receives the temperature signal T transmitted by the temperature sensing component (2) and has a built-in thermal prediction model.
4. The adaptive speed control mechanism for a brushless motor control chip with over-temperature protection according to claim 1, characterized in that: The analog comparator (41) has a built-in temperature reference, receives temperature signals T1, T2, and T3 transmitted by the temperature sensing component (2), and compares them with the built-in temperature reference. The analog comparator (41) is connected to and outputs signals to the three-phase half-bridge power switch (61).
5. The adaptive speed control mechanism for a brushless motor control chip with over-temperature protection according to claim 1, characterized in that: The speed control component (5) includes a limiter (52), which is arranged in multiple ways, and the speed control component (5) also includes a temperature-speed reduction mapping (51) recorded in the control chip component (3).
6. The adaptive speed regulation mechanism for a brushless motor control chip with over-temperature protection according to claim 5, characterized in that: The temperature-speed reduction mapping (51) includes the maximum permissible output ratio K associated with the temperature signal T transmitted by the temperature sensing component (2).
7. The adaptive speed control mechanism for a brushless motor control chip with over-temperature protection according to claim 6, characterized in that: The limiter (52) functions as minimum permissible speed limit, maximum permissible drop depth limit and thermal limit, respectively.
8. The adaptive speed regulation mechanism for a brushless motor control chip with over-temperature protection according to claim 1, characterized in that: The power stage component (6) also includes a gate drive power supply (62), a bootstrap capacitor (63) and a current sampling resistor (64), which drive the three-phase half-bridge power switch (61) through the gate drive power supply (62) and the bootstrap capacitor (63), and the current sampling resistor (64) is arranged in multiple ways and is set on the low side of the three-phase bridge of the motor (7).