Hybrid control system for a direct current motor

Abstract

This utility model relates to a hybrid control system for a DC motor, comprising a control unit and a drive circuit. The input and output terminals of the drive circuit are electrically connected to the output terminal of the control unit and the DC motor, respectively. The system also includes a Hall effect sensor module and a current sampling circuit. The Hall effect sensor module includes three Hall effect sensors, and its signal output terminal is electrically connected to the first set of signal input terminals of the control unit. The current sampling module includes three sets of differential operational amplifier circuits, with their input terminals electrically connected to the output terminals of the drive circuit and their signal output terminals electrically connected to the second set of signal input terminals of the control unit. This system solves the problem of system failure caused by a single point of failure of the Hall effect sensor through an integrated fault detection and switching mechanism, thereby achieving a balance between reliable startup, high-precision operation, and high redundancy.

Description

Technical Field

[0001] This utility model relates to the field of DC motor control technology, specifically to a hybrid control system for DC motor starting and running that balances starting reliability and high operating precision, and has fault redundancy capability. Background Technology

[0002] Brushless DC motors are widely used due to their high efficiency and long lifespan. The control method of a brushless DC motor directly determines the overall performance of the equipment. Currently, the mainstream control methods are divided into two types: sensory control and sensorless control.

[0003] Sensor-based control typically involves installing three Hall effect sensors inside the motor to directly detect the position of the rotor's magnetic poles. The advantages of this method are direct and reliable start-up, accurate rotor initial position determination by the controller, and a simple control algorithm. However, its disadvantages are also apparent. Hall effect sensors can only provide discrete, low-resolution position signals (typically a change of 60 electrical degrees). In applications requiring high precision and smooth motor operation, this discrete signal can lead to control delays and torque ripple, impacting performance. Furthermore, as physical devices, Hall effect sensors are susceptible to failure; if damaged, the entire motor will fail to start or operate.

[0004] Sensorless control does not rely on position sensors; instead, it estimates the rotor position by detecting the back electromotive force (EMF) of the motor windings or by injecting high-frequency signals. Its advantages include eliminating Hall effect sensors, reducing costs and potential failure points, and enabling very smooth and high-precision control through advanced algorithms such as Field-Oriented Control (FOC) when the motor is running at high speeds. However, its main drawback is that when the motor is stationary or at low speeds, the weak back EMF is difficult to detect, making the determination of the rotor's initial position very complex and not always accurate. This makes the starting process more difficult and prone to starting failures or reverse rotation.

[0005] In summary, existing technologies generally suffer from the problem of difficulty in balancing startup reliability and operational stability, and lack of redundancy design for critical sensor failures. Utility Model Content

[0006] The technical problem to be solved by this utility model is to overcome the shortcomings of insufficient precision in sensor control and difficulty in starting sensorless control in the prior art, and to provide a hybrid control system for DC motors. This system solves the problem of system failure caused by single-point failure of Hall sensor through an integrated fault detection and switching mechanism, thereby achieving a balance between reliable start-up, high-precision operation and high redundancy.

[0007] To address the aforementioned technical problems, this hybrid control system for DC motors is applied to the control of DC motors. It includes a control unit and a drive circuit. The input and output terminals of the drive circuit are electrically connected to the output terminal of the control unit and the DC motor, respectively. The system also includes a Hall effect sensor module and a current sampling circuit. The Hall effect sensor module includes three Hall effect sensors, and its signal output terminal is electrically connected to the first set of signal input terminals of the control unit. The current sampling module includes three sets of differential operational amplifier circuits. The input terminals of the differential operational amplifier circuits are electrically connected to the output terminals of the drive circuit, and their signal output terminals are electrically connected to the second set of signal input terminals of the control unit.

[0008] Specifically, the control unit uses an MCU microcontroller U3. The three digital I / O input terminals PB3, PB4, and PB5 of the MCU microcontroller U3 for receiving Hall sensor signals are electrically connected to the signal output terminals of the three Hall sensors in the Hall sensor module, respectively. The three ADC input terminals PA0, PA1, and PA2 of the MCU microcontroller U3 for receiving current sampling signals are electrically connected to the signal output terminals of the current sampling module, respectively. The six PWM output terminals PA8, PA9, PA10, PA7, PB0, and PB1 of the MCU microcontroller U3 are electrically connected to the control signal input terminals of the drive circuit.

[0009] Specifically, the drive circuit includes an IPM module U2 and three current sampling resistors R12, R13, and R15 connected in series between the lower bridge arm output terminals NU and NVNW of the IPM module U2 and the ground terminal, respectively. The six control signal input terminals UHIN, VHIN, WHIN, ULIN, VLIN, and WLIN of the IPM module U2 are electrically connected to the PWM output terminal of the control unit, and the three-phase power output terminals U, V, and W of the IPM module U2 are electrically connected to the DC motor. The non-grounded terminals of the three current sampling resistors R12, R13, and R15 are connected to the input terminals of the current sampling module as current sampling points Iu-, Iv-, and Iw.

[0010] Specifically, the Hall sensor module includes three Hall sensors HL1, HL2, and HL3. The signal output terminals of the three Hall sensors are connected to the corresponding I / O input terminals of the control unit via current-limiting resistors R18, R19, and R20, respectively, as the signal output terminals HALL1, HALL2, and HALL3 of the module.

[0011] Specifically, the current sampling module includes three sets of differential operational amplifier circuits with identical structures. The two differential input terminals Iw+ and Iw- of each differential operational amplifier circuit are respectively connected to the two ends of the DC motor phase current sampling resistor. The signal output terminal Iw_out of each differential operational amplifier circuit is respectively connected to the corresponding ADC input terminal of the control unit. The output terminal of each differential operational amplifier circuit is also connected to an RC filter circuit composed of resistor R1 and capacitor C1.

[0012] Specifically, it also includes a speed signal input module, which includes a first resistor R8 and a second resistor R10 connected in series. The input terminal Speed_Vsp of the module is the non-series terminal of the first resistor R8, and the output terminal Speed_Vsp_In of the module is the non-series terminal of the second resistor R10 and is electrically connected to the control unit. An RC filter circuit consisting of a pull-down resistor (R9) and a first capacitor C9 connected in series is connected in parallel between the connection point of the first resistor R8 and the second resistor R10 and the ground terminal, and a diode array D1 for clamping protection.

[0013] This invention overcomes the shortcomings of insufficient precision in sensor-based control and difficulty in starting sensorless control in the prior art. It solves the problem of system failure caused by single-point failure of Hall sensor through an integrated fault detection and switching mechanism, thereby achieving a balance between reliable start-up, high-precision operation and high redundancy. Attached Figure Description

[0014] The hybrid control system for a DC motor according to this utility model will be further described below with reference to the accompanying drawings:

[0015] Figure 1 This is a block diagram showing the overall logic structure and connection relationships of the hybrid control system for this DC motor;

[0016] Figure 2 This is the circuit schematic diagram of the control unit of the hybrid control system for this DC motor;

[0017] Figure 3 This is the circuit schematic diagram of the drive circuit of the hybrid control system for this DC motor;

[0018] Figure 4 This is the circuit schematic of the Hall sensor module described in the hybrid control system of this DC motor;

[0019] Figure 5 This is the circuit schematic of the current sampling module of the hybrid control system for this DC motor;

[0020] Figure 6 This is the circuit schematic diagram of the speed signal input module of the hybrid control system for this DC motor;

[0021] Figure 7 This is the operation flowchart of the hybrid control system for this DC motor.

[0022] In the picture:

[0023] 1-Control unit, 2-Drive circuit, 3-Hall sensor module, 4-Current sampling module, 5-Speed ​​signal input module. Detailed Implementation

[0024] In this utility model, unless otherwise explicitly specified and limited, the terms "installation," "connection," "joining," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. For those skilled in the art, the specific meaning of the above terms in this utility model can be understood according to the specific circumstances.

[0025] In the description of this utility model, it should be understood that the terms "left", "right", "front", "rear", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship 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 this utility model.

[0026] The present invention will be further described below with specific embodiments, but the scope of protection of the present invention is not limited to the following embodiments.

[0027] Implementation method 1: such as Figure 1As shown, this hybrid control system for a DC motor is used to control a DC motor. It includes a control unit 1 and a drive circuit 2. The input and output terminals of the drive circuit 2 are electrically connected to the output terminal of the control unit 1 and the DC motor, respectively. It also includes a Hall effect sensor module 3 and a current sampling circuit 4. The Hall effect sensor module 3 includes three Hall effect sensors, and its signal output terminal is electrically connected to the first set of signal input terminals of the control unit 1. The current sampling module 4 includes three sets of differential operational amplifier circuits. The input terminals of the differential operational amplifier circuits are electrically connected to the output terminals of the drive circuit 2, and their signal output terminals are electrically connected to the second set of signal input terminals of the control unit 1. In the initial stage of motor startup, a sensor-based mode is preferentially used. The control unit 1 directly reads the signal from the Hall effect sensor module 3 to accurately determine the initial position of the rotor, and the drive circuit 2, acting as the actuator, quickly and reliably starts the motor. Once the motor enters a stable operating phase, it switches to a sensorless mode. The control unit 1 uses the real-time current data obtained from the current sampling module 4 to perform high-precision closed-loop operation control of the motor through the drive circuit 2. The control unit 1 monitors the status of the Hall sensor module 3 in real time. When a fault is detected (such as reading an illegal sector value of 0 or 7 when powered on, or the signal not changing for a long time during operation), it automatically switches to a preset, purely sensorless "three-stage pre-positioning" start-up scheme. This ensures that even if the Hall sensor is physically damaged, the motor can still start and run, greatly improving the reliability and fault tolerance of the entire system.

[0028] Implementation method 2: such as Figure 2 As shown, the control unit 1 of this DC motor hybrid control system uses an MCU microcontroller U3. The three digital I / O input terminals PB3, PB4, and PB5 of the MCU U3 form the first set of signal input terminals, which are electrically connected to the signal output terminals of the three Hall sensors in the Hall sensor module 3, respectively, for reading the rotor position signal. The three ADC input terminals PA0, PA1, and PA2 of the MCU U3 form the second set of signal input terminals, which are electrically connected to the signal output terminals of the current sampling module 4, respectively, for acquiring the motor phase current. The six PWM output terminals PA8, PA9, PA10, PA7, PB0, and PB1 of the MCU U3 serve as control output terminals, which are electrically connected to the control signal input terminals of the drive circuit 2, for precisely controlling the energizing timing and voltage of the motor windings. By explicitly defining the interfaces of each functional module to the specific physical pins of the MCU U3, a precise and implementable hardware connection example is provided for this technical solution, ensuring the clarity and reliability of the signal transmission path. The remaining structures and components are as described in Embodiment 1 and will not be repeated.

[0029] Implementation method 3: such as Figure 3As shown, the drive circuit 2 of the hybrid control system for this DC motor includes an IPM module U2 and three current sampling resistors R12, R13, and R15 connected in series between the lower bridge arm output terminals NU, NVNW and ground of the IPM module U2. The six control signal input terminals UHIN, VHIN, WHIN, ULIN, VLIN, and WLIN of the IPM module U2 are electrically connected to the PWM output terminal of the control unit 1. The three-phase power output terminals U, V, and W of the IPM module U2 are electrically connected to the DC motor. The non-grounded terminals of the three current sampling resistors R12, R13, and R15 serve as current sampling points Iu-, Iv-, and Iw, connected to the input terminals of the current sampling module 4. The IPM module U2 integrates power switching transistors and drive and protection circuits. Using the IPM module U2 simplifies the design of the three-phase inverter bridge and improves the reliability of the power section. Placing the current sampling resistors R12, R13, and R15 in the lower bridge arm is a mature, economical, and effective method for sampling phase current. Its compact structure facilitates integration with the operational amplifier conditioning circuit, providing accurate current feedback for the sensorless control stage. The remaining structures and components are as described in Embodiment 1 and will not be repeated.

[0030] Implementation method 4: such as Figure 4 , 5As shown, the Hall sensor module 3 of the hybrid control system for this DC motor includes three Hall sensors HL1, HL2, and HL3. The signal output terminals of the three Hall sensors are connected to the corresponding I / O input terminals of the control unit 1 via current-limiting resistors R18, R19, and R20, respectively. The signals from these three sensors are combined into a 3-bit binary number, which can indicate six different sectors, corresponding to six position ranges of the rotor. The current-limiting resistors R18, R19, and R20 are necessary protections for the input pins of the control unit 1 (such as the I / O ports of the MCU), preventing overcurrent damage caused by electrical transients or unexpected conditions. This is a simple and effective design to ensure the long-term stable operation of the system hardware. The current sampling module 4 includes three sets of identical differential operational amplifier circuits. The two differential input terminals Iw+ and Iw- of each differential operational amplifier circuit are connected to the two ends of the DC motor phase current sampling resistor, respectively. The signal output terminal Iw_out of each differential operational amplifier circuit is connected to the corresponding ADC input terminal of the control unit 1. The output terminal of each differential operational amplifier circuit is also connected to an RC filter circuit composed of resistor R1 and capacitor C1. The differential operational amplifier circuit is used to accurately capture the weak voltage drop generated by the current flowing through the lower bridge arm sampling resistors (such as R12, R13, and R15), which is proportional to the motor phase current. In the strong electromagnetic interference environment of motor drive, the differential amplification method can effectively suppress common-mode noise interference and extract the measured signal from the noise. The amplified signal voltage is adjusted to a range suitable for the internal ADC (analog-to-digital converter) of the control unit 1, ensuring the accuracy and resolution of the current sampling. The RC filter circuit set at the output end further filters out high-frequency glitches in the signal, making the current feedback value obtained by the control unit 1 smoother and more stable. This is crucial for achieving high-precision FOC (field-oriented control) algorithm in the subsequent sensorless operation phase and is the foundation for ensuring the smooth and efficient operation of the motor.

[0031] Implementation method 5: such as Figure 6As shown, the hybrid control system of this DC motor also includes a speed signal input module 5. The speed signal input module 5 includes a first resistor R8 and a second resistor R10 connected in series. The input terminal Speed_Vsp of the module is the non-series terminal of the first resistor R8, and the output terminal Speed_Vsp_In of the module's input terminal is the non-series terminal of the second resistor R10 and is electrically connected to the control unit 1. An RC filter circuit consisting of a pull-down resistor R9 and a first capacitor C9 connected in series, and a diode array D1 for clamping protection are connected in parallel between the connection point of the first resistor R8 and the second resistor R10 and the ground terminal. The module filters the potentially unstable speed command voltage (Speed_Vsp) input from the outside through the RC circuit and clamps it through the diode array D1, processing it into a stable and safe analog signal Speed_Vsp_In, which is then sent to the control unit 1 as the target speed for motor operation.

[0032] At runtime: such as Figure 7 As shown, after the system is powered on, the control unit 1 first receives a start command (e.g., detecting that Speed_Vsp_In is greater than a preset threshold) and immediately reads the three level signals of the Hall sensor module 3 to calculate the current Hall sector value. The control unit 1 checks the sector value. If the value is a normal value between 1 and 6, the Hall sensor is considered normal. If the value is 0 or 7, the Hall sensor module is considered to have a short circuit or open circuit fault. If the Hall sensor is normal, the control unit 1 looks up the approximate angle range of the rotor according to the sector value in a table. Based on this, it directly controls the drive circuit 2 to generate a suitable rotating magnetic field, starting the motor and pulling it into the running state. When the speed increases, the system switches to a sensorless control mode. At this time, the Hall signal is no longer used for closed-loop control. Instead, the control unit 1 executes the FOC algorithm based on the feedback from the current sampling module 4 to achieve precise control of the motor torque and flux linkage.

[0033] If a Hall fault is detected upon power-up, or if, during motor operation, control unit 1 detects that the level of any Hall signal remains unchanged for more than 30 seconds (it should alternate during normal operation), a Hall fault will also be identified. In this case, control unit 1 automatically switches to a "three-stage pre-positioning" sensorless start mode. This mode uses a specific power-on sequence to first forcibly position the rotor to a known initial angle, then applies a rotating magnetic field to start it, and once a certain speed is reached, it switches to FOC closed-loop operation.

[0034] It should be noted that the switching trigger conditions in this embodiment all come from hardware signals (Hall sensor module, current sampling module). The FOC (field orientation control) algorithm and the "three-stage pre-positioning" mentioned in the pure sensorless start method are mature algorithm technologies widely used in the field of DC brushless motor control. Their specific program implementation logic is common knowledge to those skilled in the art. This embodiment does not make any improvement or optimization to the above algorithms themselves.

[0035] This invention overcomes the shortcomings of insufficient precision in sensor-based control and difficulty in starting sensorless control in existing technologies. Through an integrated fault detection and switching mechanism, it solves the problem of system failure caused by a single point of failure in the Hall sensor, thereby achieving a balance between reliable startup, high-precision operation, and high redundancy. Specifically, its beneficial effects are as follows:

[0036] 1. Reliable start-up and smooth operation: It combines the fast and accurate start-up of sensored start-up with the high precision and smooth operation of sensorless operation, giving full play to its strengths and avoiding its weaknesses, and optimizing the motor's performance across the entire speed range.

[0037] 2. Structural Fault Redundancy: Through the built-in Hall fault real-time diagnosis and automatic control mode switching structural design, the pain point of traditional sensor motors being completely paralyzed due to sensor failure is solved, and the system reliability and robustness are significantly improved.

[0038] 3. Simplified control and improved performance: No complex sensorless pre-positioning algorithm is required during startup, and conventional FOC sensorless control, which is commonly used in the industry, is adopted during operation. This avoids torque pulsation caused by Hall signal delay, thereby improving control accuracy.

[0039] The above description illustrates the main features, basic principles, and advantages of this utility model. It will be apparent to those skilled in the art that this utility model is not limited to the details of the exemplary embodiments or examples described above, and that it can be implemented in other specific forms without departing from the spirit or basic characteristics of this utility model. Therefore, the above embodiments or examples should be considered exemplary and not restrictive. The scope of this utility model is defined by the appended claims rather than the foregoing description, and therefore all variations falling within the meaning and scope of equivalents of the claims are intended to be included within this utility model. No reference numerals in the claims should be construed as limiting the scope of the claims.

[0040] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A hybrid control system for a DC motor, applied to the control of a DC motor, comprising a control unit (1) and a drive circuit (2), wherein the input terminal and output terminal of the drive circuit (2) are electrically connected to the output terminal of the control unit (1) and the DC motor, respectively, characterized in that: It also includes a Hall sensor module (3) and a current sampling circuit (4); The Hall sensor module (3) includes three Hall sensors. The signal output terminal of the Hall sensor module (3) is electrically connected to the first group of signal input terminals of the control unit (1). The current sampling circuit (4) includes three groups of differential operational amplifier circuits. The input terminal of the differential operational amplifier circuit is electrically connected to the output terminal of the drive circuit (2). The signal output terminal of the differential operational amplifier circuit is electrically connected to the second group of signal input terminals of the control unit (1).

2. The hybrid control system for a DC motor according to claim 1, characterized in that: The control unit (1) uses an MCU microcontroller U3. The three digital I / O input terminals PB3, PB4, and PB5 of the MCU microcontroller U3 for receiving Hall sensor signals are electrically connected to the signal output terminals of the three Hall sensors in the Hall sensor module (3). The three ADC input terminals PA0, PA1, and PA2 of the MCU microcontroller U3 for receiving current sampling signals are electrically connected to the signal output terminals of the current sampling circuit (4). The six PWM output terminals PA8, PA9, PA10, PA7, PB0, and PB1 of the MCU microcontroller U3 are electrically connected to the control signal input terminals of the drive circuit (2).

3. The hybrid control system for a DC motor according to claim 2, characterized in that: The drive circuit (2) includes an IPM module U2 and three current sampling resistors R12, R13, and R15 connected in series between the lower bridge arm output terminals NU, NVNW and the ground terminal of the IPM module U2. The six control signal input terminals UHIN, VHIN, WHIN, ULIN, VLIN, and WLIN of the IPM module U2 are electrically connected to the PWM output terminal of the control unit (1). The three-phase power output terminals U, V, and W of the IPM module U2 are electrically connected to the DC motor. The non-grounded terminals of the three current sampling resistors R12, R13, and R15 are connected to the input terminal of the current sampling circuit (4) as current sampling points Iu-, Iv-, and Iw.

4. The hybrid control system for a DC motor according to claim 3, characterized in that: The Hall sensor module (3) includes three Hall sensors HL1, HL2, and HL3. The signal output terminals of the three Hall sensors are connected to the corresponding I / O input terminals of the control unit (1) via current-limiting resistors R18, R19, and R20, respectively.

5. The hybrid control system for a DC motor according to claim 4, characterized in that: The current sampling circuit (4) includes three sets of differential operational amplifier circuits with the same structure. The two differential input terminals Iw+ and Iw- of each set of differential operational amplifier circuits are respectively used to connect to the two ends of the DC motor phase current sampling resistor. The signal output terminal Iw_out of each set of differential operational amplifier circuits is respectively connected to the corresponding ADC input terminal of the control unit (1). The output terminal of each set of differential operational amplifier circuits is also connected to an RC filter circuit composed of resistor R1 and capacitor C1.

6. The hybrid control system for a DC motor according to claim 5, characterized in that: It also includes a speed signal input module (5), which includes a first resistor R8 and a second resistor R10 connected in series. The input terminal Speed_Vsp of the module is the non-series terminal of the first resistor R8, and the output terminal Speed_Vsp_In of the module is the non-series terminal of the second resistor R10 and is electrically connected to the control unit (1). An RC filter circuit consisting of a pull-down resistor R9 and a first capacitor C9 connected in series and a diode array D1 for clamping protection are connected in parallel between the connection point of the first resistor R8 and the second resistor R10 and the ground terminal.

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