Motor control chip, system and method

Abstract

The present invention provides a motor control chip, system and method, including: a motor drive control circuit and at least two sensors; each sensor is arranged in sequence and spaced apart, and is used to detect the magnetic field to be measured and generate corresponding electrical signals respectively; at least two sensors are at equal distances from the motor shaft, and the angle between the two outermost sensors and the motor shaft is not greater than half of the motor's electrical cycle; the motor drive control circuit receives the output signal of each sensor, and generates a motor drive signal based on the output signal of each sensor. The present invention integrates the sensor into the chip, greatly reducing the size and cost of the motor control circuit; the control algorithm is switched according to the motor speed, and a low-speed magnetic field oriented control algorithm with a position sensor is used at low speed, and a magnetic field oriented control algorithm without a position sensor is used at high speed, so as to achieve more stable and reliable motor control.

Description

Technical Field

[0001] The present invention relates to the field of motor control, and in particular to a motor control chip, system and method. Background Art

[0002] Three-phase permanent magnet synchronous motor (BLDC: Brushless DC Motor) has been widely used in consumer, industrial and automotive products. BLDC drive and control technology has also developed accordingly, among which sensorless BLDC control scheme is highly respected due to its high reliability. However, sensorless technology has fatal defects in the low speed and starting stage of the motor, such as starting swing and starting noise; it cannot completely replace Hall or other sensors.

[0003] With the development of semiconductor technology, highly integrated motor control chips have tried to integrate control algorithms and drive circuits into one chip, and have achieved some success. However, sensors (typically Hall sensors) have not been integrated because they require two cells or more and have strict requirements on their position on the chip. The common system currently has an integrated or non-integrated control and drive IC, and three external sensors, which are installed at 120° or 60° intervals. Figure 1 Schematic diagram of three sensors 1a, 1b, and 1c installed at 120° intervals.

[0004] Therefore, how to improve the integration and reliability of motor control while reducing the size and cost has become one of the urgent problems to be solved by those skilled in the art.

[0005] It should be noted that the above introduction to the technical background is only for the convenience of providing a clear and complete description of the technical solutions of the present application and for the convenience of understanding by those skilled in the art. It cannot be considered that the above technical solutions are well known to those skilled in the art simply because they are described in the background technology section of the present application. Summary of the invention

[0006] In view of the above-mentioned shortcomings of the prior art, the purpose of the present invention is to provide a motor control chip, system and method for solving the problems in the prior art that sensors in motor control cannot be integrated into chips, resulting in large size, high cost, and the reliability of motor control needs to be improved.

[0007] To achieve the above-mentioned object and other related objects, the present invention provides a motor control chip for controlling a three-phase brushless DC motor, the motor control chip comprising:

[0008] a motor drive control circuit and at least two sensors;

[0009] The sensors are arranged in sequence and spaced apart to detect the magnetic field to be measured and generate corresponding electrical signals respectively; at least two sensors are at equal distances from the motor shaft, and the angle between the two outermost sensors and the motor shaft is no greater than half of the electrical period of the motor;

[0010] The motor drive control circuit receives output signals of the sensors and generates a motor drive signal based on the output signals of the sensors.

[0011] Optionally, the distances from each sensor to the motor shaft are equal.

[0012] More optionally, the angle between the two sensors and the motor shaft is one quarter of the electrical cycle.

[0013] Optionally, the sensor is a Hall sensor, an anisotropic magnetoresistive sensor or a tunnel magnetoresistive sensor.

[0014] Optionally, the motor drive control circuit includes a current detection unit, an analog-to-digital converter, a control logic unit, a pre-drive unit and a power unit;

[0015] The current detection unit detects the phase current of the motor;

[0016] The analog-to-digital converter is connected to the output end of the current detection unit and each sensor, and is used to perform analog-to-digital conversion on the output signal of the current detection unit and the output signal of each sensor;

[0017] The control logic unit is connected to the output end of the analog-to-digital converter and generates a motor control signal based on the output signal of the analog-to-digital converter;

[0018] The pre-driving unit is connected to the output end of the control logic unit and generates a pre-driving signal based on the motor control signal;

[0019] The power unit is controlled by the pre-driving signal to generate the motor driving signal.

[0020] More optionally, the control logic unit executes a low-speed magnetic field oriented control algorithm based on the output signals of each sensor and the output signal of the current detection unit to generate a corresponding motor control signal when the motor is running at a low speed; and executes a position sensorless magnetic field oriented control algorithm based on the output signal of the current detection unit to generate a corresponding motor control signal when the motor is running at a high speed.

[0021] In order to achieve the above-mentioned object and other related objects, the present invention further provides a motor control system, the motor control system comprising:

[0022] Circuit board, three-phase brushless DC motor and the above motor control chip;

[0023] The three-phase brushless DC motor comprises a stator and a rotor coaxially arranged along the motor shaft, the circuit board is fixed on the stator of the three-phase brushless DC motor, and the plane where the circuit board is located is perpendicular to the axial direction of the three-phase brushless DC motor;

[0024] The motor control chip is arranged on the circuit board, and is used for detecting the magnetic field and phase current of the three-phase brushless DC motor, and generating a motor driving signal based on the detected signal to control the operation of the three-phase brushless DC motor.

[0025] Optionally, each sensor on the motor control chip covers the gap between the stator and the rotor.

[0026] Optionally, the circuit board is a circular structure, the circuit board is coaxially arranged with the stator and the rotor, and the radius of the circuit board is greater than the radius of the stator and the rotor.

[0027] In order to achieve the above object and other related objects, the present invention further provides a motor control method, which is implemented based on the above motor control system. The motor control method includes:

[0028] After power-on or receiving a start command, the initial speed of the motor is obtained. If the initial speed is less than a preset value, the motor is controlled based on a low-speed magnetic field oriented control algorithm; if the initial speed is greater than or equal to the preset value, the motor is controlled based on a position sensorless magnetic field oriented control algorithm;

[0029] During the execution of the low-speed magnetic field oriented control algorithm, if the motor speed is greater than or equal to the high-speed threshold, switch to the magnetic field oriented control algorithm without position sensor; otherwise, continue to execute the low-speed magnetic field oriented control algorithm;

[0030] During the execution of the sensorless magnetic field oriented control algorithm, if the motor speed is less than or equal to the low speed threshold, switching to the low speed magnetic field oriented control algorithm; otherwise, continuing to execute the sensorless magnetic field oriented control algorithm;

[0031] The high-speed threshold is greater than the low-speed threshold.

[0032] Optionally, the output signal of each sensor is analyzed based on trigonometric functions, and the low-speed magnetic field oriented control algorithm obtains the position of the rotor based on the analysis result, thereby realizing motor control.

[0033] Optionally, when the motor control chip includes at least three sensors, output signals of any two sensors obtain an analysis result, and the analysis results are averaged or corrected.

[0034] As described above, the motor control chip, system and method of the present invention have the following beneficial effects:

[0035] 1. The motor control chip of the present invention integrates the sensor into the chip, which greatly reduces the size and cost of the motor control circuit.

[0036] 2. The motor control chip, system and method of the present invention switch the control algorithm according to the motor speed. At low speed, a low-speed magnetic field oriented control algorithm with a position sensor is adopted, and at high speed, a magnetic field oriented control algorithm without a position sensor is adopted. The advantages of the low-speed magnetic field oriented control algorithm and the magnetic field oriented control algorithm without a position sensor are taken into account to achieve more stable and reliable motor control. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 The figure shows a schematic diagram of sensor installation in the prior art.

[0038] Figure 2 Shown is a schematic diagram of the structure of the motor control chip of the present invention.

[0039] Figure 3 Shown is a schematic structural diagram of the motor control system of the present invention.

[0040] Figure 4 Shown is a schematic structural diagram of the three-phase DC brushless motor of the present invention.

[0041] Figure 5 It is a flow chart of the motor control method of the present invention.

[0042] Figure 6 It is a schematic diagram showing the principle of calculating the electrical angle of the motor when the output signals of the two sensors of the present invention are orthogonal.

[0043] Figure 7 It is a schematic diagram showing the case where the output signals of two sensors of the present invention are not orthogonal.

[0044] Figure 8 It is a schematic diagram showing the principle of calculating the electrical angle of the motor when the output signals of the two sensors of the present invention are not orthogonal.

[0045] Component number description

[0046] 1a, 1b, 1c Sensors

[0047] 2 Motor control chip

[0048] 21 Motor drive control circuit

[0049] 211 Current detection unit

[0050] 212 Analog-to-digital converter

[0051] 213 Control Logic Unit

[0052] 214 Pre-driver unit

[0053] 215 Power Unit

[0054] 216 Amplification filter

[0055] 217a First regulator

[0056] 217b Second regulator

[0057] 218 Charge Pump

[0058] 219 Abnormal Protection Unit

[0059] 221 First Sensor

[0060] 222 Second sensor

[0061] 3 Circuit Board

[0062] 4 Three-phase brushless DC motor

[0063] 41 Stator

[0064] 42 Rotor

[0065] 42a Antarctic Region

[0066] 42b Arctic Region DETAILED DESCRIPTION

[0067] The following describes the embodiments of the present invention through specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention.

[0068] See also Figure 2 to Figure 8 It should be noted that the illustrations provided in this embodiment are only used to illustrate the basic concept of the present invention in a schematic manner, and the drawings only show components related to the present invention rather than being drawn according to the number, shape and size of components in actual implementation. In actual implementation, the type, quantity and proportion of each component may be changed arbitrarily, and the component layout may also be more complicated.

[0069] Embodiment 1

[0070] like Figure 2 As shown, this embodiment provides a motor control chip 2 for controlling a three-phase brushless DC motor. The motor control chip 2 includes:

[0071] The motor drive control circuit 21 and at least two sensors.

[0072] like Figure 2 As shown, the sensors are arranged in sequence and are used to detect the magnetic field to be measured and generate corresponding electrical signals respectively; at least two sensors are at an equal distance from the motor shaft, and the angle θ between the outermost two sensors and the motor shaft is not greater than half of the electrical period of the motor.

[0073] Specifically, in this embodiment, two sensors are provided, which are recorded as a first sensor 221 and a second sensor 222. The first sensor 221 and the second sensor 222 are separated by a distance, and the first sensor 221 and the second sensor 222 are at the same distance from the motor shaft; that is, the first sensor 221 and the second sensor 222 are located on a circle with the motor shaft as the center, and the radius of the circle is related to the magnetic field strength detected by the sensor and the position of the sensor on the motor, and can be set according to actual needs, which will not be described in detail here.

[0074] Specifically, the line segment from the first sensor 221 to the motor shaft and the line segment from the second sensor 222 to the motor shaft form an angle θ, and the angle θ is not greater than one-half of the electrical cycle. If the angle θ is one-fourth of the electrical cycle, the output signal of the first sensor 221 and the output signal of the second sensor 222 are orthogonal signals; if the angle θ is greater than zero and less than one-fourth of the electrical cycle, or greater than one-fourth of the electrical cycle and less than one-fourth of the electrical cycle, the output signal of the first sensor 221 and the output signal of the second sensor 222 are non-orthogonal signals. As an example, in this embodiment, the angle θ is set to one-fourth of the electrical cycle, and the phase difference between the output signal of the first sensor 221 and the output signal of the second sensor 222 is 90°, which can simplify the angle analysis of the sensor output signal and improve the operation efficiency.

[0075] Specifically, the first sensor 221 and the second sensor 222 detect the magnetic field to be measured and generate corresponding electrical signals respectively (the output electrical signals are proportional to the magnetic field at the location of the sensor), including but not limited to Hall sensors, Anisotropic Magneto Resistance (AMR) sensors or Tunnel Magneto Resistance (TMR) sensors. Any sensor that can detect magnetic signals and generate corresponding electrical signals is suitable for the present invention and they are not listed here one by one.

[0076] like Figure 2As shown, the motor drive control circuit 21 receives the output signals of each sensor and generates a motor drive signal based on the output signals of each sensor.

[0077] Specifically, in this embodiment, the motor drive control circuit 21 includes a current detection unit 211, an analog-to-digital converter 212, a control logic unit 213, a pre-drive unit 214 and a power unit 215. The current detection unit 211 detects the phase current of the motor; for a three-phase motor, the current detection unit 211 collects any two-phase currents, and the third-phase current can be calculated by a formula. In actual use, only two-phase currents can be collected, or the three-phase currents can be detected separately to directly obtain the three-phase currents; any device that can realize current detection is applicable to the current detection unit 211 of the present invention, including but not limited to mutual inductors, which are not described one by one here. The analog-to-digital converter 212 is connected to the output end of the current detection unit 211 and each sensor, and is used to perform analog-to-digital conversion on the output signal of the current detection unit 211 and the output signal of each sensor; any circuit structure that can convert an analog signal into a digital signal is applicable to the present invention. The control logic unit 213 is connected to the output end of the analog-to-digital converter 212, and generates a motor control signal based on the output signal of the analog-to-digital converter 212; in this example, the control logic unit 213 executes a low-speed magnetic field oriented control algorithm based on the output signals of each sensor and the output signal of the current detection unit 211 when the motor is running at a low speed to generate a corresponding motor control signal; when the motor is running at a high speed, the magnetic field oriented control algorithm without a position sensor is executed based on the output signal of the current detection unit 211 to generate a corresponding motor control signal, wherein low speed means that the motor speed is less than a preset value, including zero speed; the control logic unit 213 can be implemented by including but not limited to MCU or other computing units, which are not described one by one here. The pre-driving unit 214 is connected to the output end of the control logic unit 213, and generates a pre-driving signal based on the motor control signal. The pre-driving unit 214 is used to improve the driving ability of the motor control signal to achieve the driving of each power tube in the power unit 215. The power unit 215 is controlled by the pre-drive signal to generate the motor drive signal (OUTA, OUTB and OUTC). As an example, the power unit 215 adopts a three-phase full-bridge inverter circuit structure, including 6 power tubes. In actual use, any circuit structure that can invert the DC voltage into a three-phase AC voltage based on the pre-drive signal is suitable for the present invention, and is not limited to this embodiment.

[0078] Specifically, as an implementation of the present invention, the motor drive control circuit 21 also includes an amplifying filter 216, which is connected between each sensor and the analog-to-digital converter 212, receives the output signal of each sensor, and amplifies and filters the output signal of each sensor to facilitate the subsequent circuit to identify the signal detected by the sensor, reduce interference, and improve accuracy.

[0079] Specifically, as an implementation of the present invention, the motor drive control circuit 21 also includes a first voltage regulator 217a and a second voltage regulator 217b; the first voltage regulator 217a is connected between the chip power supply VM and the control logic unit 213, and stabilizes the working power supply of the control logic unit 213; the second voltage regulator 217b is connected between the chip power supply VM and the pre-drive unit 214, and is used to stabilize the working power supply of the pre-drive unit 214; thereby improving the anti-interference ability.

[0080] Specifically, as an implementation of the present invention, the motor drive control circuit 21 also includes a charge pump 218, which is connected between the chip power supply VM and the pre-drive unit 214 to raise the voltage value of the chip power supply VM, thereby improving the driving capability of the pre-drive signal.

[0081] Specifically, as an implementation method of the present invention, the motor drive control circuit 21 also includes an abnormality protection unit 219, which detects various faults and abnormalities, and sends the fault and abnormality detection signals to the control logic unit 213. The control logic unit 213 controls the motor accordingly based on the fault and abnormality detection signals to improve reliability; wherein, the faults and abnormalities include but are not limited to overcurrent, overtemperature, overvoltage, undervoltage, open circuit, short circuit, and any faults and abnormalities that affect the safety of the chip and the motor are applicable to the present invention and will not be described one by one here.

[0082] The motor control chip of the present invention integrates sensors and motor drive control circuits into the chip, greatly reducing the size and cost of the motor control circuit; at the same time, the motor control chip of the present invention adopts different control algorithms for the motor based on the motor speed, thereby greatly improving the reliability and accuracy of the motor control.

[0083] Embodiment 2

[0084] This embodiment provides a motor control chip 2 , which is different from the first embodiment in that three or more sensors are integrated in the motor control chip 2 .

[0085] Specifically, when the number of sensors is three or more, the setting method of two of the sensors is consistent with the first sensor and the second sensor in Example 1; the remaining sensors are set between the first sensor and the second sensor as redundancy, and each sensor is separated by a distance.

[0086] Specifically, as an example, the redundant sensors are evenly distributed between the first sensor and the second sensor (i.e., two adjacent sensors form an angle θ with respect to the motor shaft, and each angle θ is equal), and the distances from each sensor to the motor shaft are equal (i.e., each sensor is located on the same circumference with the motor shaft as the center). In this case, the calculation accuracy and subsequent control accuracy are the highest. In actual use, the redundant sensors may have a certain deviation from the circumference of the first sensor and the second sensor. The deviation amount is subject to the error range allowed by the subsequent calculation. The larger the deviation, the lower the accuracy. The redundant sensors may also be unevenly distributed between the first sensor and the second sensor, in which case the calculation complexity increases.

[0087] Specifically, as an example, the angle θ between the two sensors and the motor shaft is one quarter of the electrical cycle, thereby simplifying the angle analysis of the sensor output signal and obtaining the rotor position. In this example, the angle θ between the first sensor and the second sensor disposed on the outermost side and the motor shaft is set to one quarter of the electrical cycle; in actual use, the angle θ between any two sensors and the motor shaft can also be set to one quarter of the electrical cycle, not limited to this embodiment.

[0088] It should be noted that the number of sensors can be set according to actual needs. In the present invention, at least the first sensor and the second sensor can complete the most basic motor control, and other sensors are used to achieve additional functions (including but not limited to improving calculation accuracy). The other components and structures of the motor control chip 2 of this embodiment are the same as those of the first embodiment, and are not described one by one here.

[0089] Embodiment 3

[0090] like Figure 3 and Figure 4 As shown, this embodiment provides a motor control system, and the motor control system includes:

[0091] A motor control chip 2, a circuit board 3 and a three-phase brushless DC motor 4.

[0092] like Figure 3 As shown, the three-phase DC brushless motor 4 includes a stator 41 and a rotor 42 coaxially arranged along the motor shaft, the circuit board 3 is fixed on the stator of the three-phase DC brushless motor 4, and the plane where the circuit board 3 is located is perpendicular to the axial direction of the three-phase DC brushless motor 4.

[0093] Specifically, Figure 4 As shown, in this embodiment, the stator 41 is a cylindrical structure, including a plurality of coils, which are used to generate a magnetic field and serve as a mechanical support for the motor. The rotor 42 is arranged at the periphery of the stator 41 and is coaxially arranged with the stator 41; the rotor 42 includes magnetic field south pole regions 42a and north pole regions 42b arranged alternately in sequence, and the south pole regions 42a and the north pole regions 42b are composed of magnetic materials. In this example, five south pole regions 42a and five north pole regions 42b are evenly arranged; the distance between the boundary line between a south pole region 42a and its adjacent north pole region 42b to the boundary line between the next south pole region 42a and its adjacent next north pole region 42b is an electrical cycle α. When the coil in the stator 41 is energized, the corresponding polarity is generated due to the magnetic effect of the current. When the polarity on the stator 41 is the same or different from the polarity of the magnetic pole (south pole region 42a and north pole region 42b) on the rotor 42, the rotor 42 is forced to rotate.

[0094] It should be noted that, in actual use, the relative positions of the stator 41 and the rotor 42 are interchangeable, that is, the rotor 42 is a cylindrical structure, and the stator 41 is coaxially arranged on the periphery of the rotor 42, which is not limited to this embodiment.

[0095] like Figure 3 As shown, the circuit board 3 is fixed on the stator 41 of the three-phase DC brushless motor, and the plane where the circuit board 3 is located is perpendicular to the axial direction of the three-phase DC brushless motor.

[0096] Specifically, the circuit board 3 is located on one side of the stator 41 and the rotor 42, and is arranged perpendicular to the motor shaft. In this example, the circuit board 3 is a circular structure, and the radius of the circuit board 3 is larger than the radius of the stator and the rotor of the three-phase DC brushless motor, so as to support and fix it; in actual use, the size and shape of the circuit board 3 can be set as needed, and it can be fixed on the stator 41 and can install the motor control chip 2.

[0097] like Figure 3 As shown, the motor control chip 2 is arranged on the circuit board 3, and is used to detect the magnetic field and phase current of the three-phase DC brushless motor, and generate a motor drive signal based on the detected signal to control the operation of the three-phase DC brushless motor.

[0098] Specifically, the motor control chip 2 adopts the motor control chip of the first or second embodiment, and the circumference of each sensor is concentric with the circumference of the stator 41 and the rotor 42. In this embodiment, each sensor on the motor control chip 2 covers the gap between the stator 41 and the rotor 42. Since the magnetic field is the strongest here, it is more conducive to obtaining an accurate detection signal; in actual use, each sensor can be close to or away from the motor shaft relative to the gap between the stator 41 and the rotor 42, and the magnetic field strength gradually weakens when approaching or moving away from the motor shaft accordingly. The motor control chip 2 can be set at a preset distance from the motor shaft as needed, and the sensor on the motor control chip 2 can detect the magnetic field and obtain an output signal with an error within an acceptable range.

[0099] Embodiment 4

[0100] like Figure 5 As shown, this embodiment provides a motor control method, which is implemented based on the motor control system of embodiment three, and the motor control method includes:

[0101] After power-on or receiving a start command, the initial speed of the motor is obtained. If the initial speed is less than a preset value, the motor is controlled based on a low-speed magnetic field oriented control algorithm; if the initial speed is greater than or equal to the preset value, the motor is controlled based on a position sensorless magnetic field oriented control algorithm; otherwise, the low-speed magnetic field oriented control algorithm continues to be executed;

[0102] During the execution of the low-speed magnetic field oriented control algorithm, if the motor speed is greater than or equal to the high-speed threshold, switch to the position sensorless magnetic field oriented control algorithm; otherwise, continue to execute the position sensorless magnetic field oriented control algorithm;

[0103] During the execution of the sensorless field oriented control algorithm, if the motor speed is less than or equal to the low speed threshold, the low speed field oriented control algorithm is switched;

[0104] The high-speed threshold is greater than the low-speed threshold.

[0105] like Figure 5 As shown, the specific steps include:

[0106] 1) Power on or receive a start command, then proceed to step 2).

[0107] 2) Determine the initial speed of the motor, wherein the initial speed can be calculated based on the sensor detection signal, or can be calculated based on the phase current and voltage, which will not be described in detail here. If the initial speed is less than the preset value (including zero speed and low speed), execute step 3); if the initial speed is greater than or equal to the preset value, execute step 7). In this embodiment, the preset value is equal to the high-speed threshold. In actual use, the preset value may be between the low-speed threshold and the high-speed threshold; the preset value may also be greater than the high-speed threshold. At this time, even if the initial speed of the motor is greater than the high-speed threshold, it can quickly switch from the low-speed magnetic field oriented control algorithm to the position sensorless magnetic field oriented control algorithm.

[0108] 3) Detect the motor magnetic field based on the sensor and convert it into a corresponding electrical signal, and then execute step 4).

[0109] 4) Performing angle analysis on the output signals of the sensors, wherein the output signals of any two sensors can be analyzed at an angle, and then executing step 5). In this embodiment, the output signals of each sensor are analyzed based on trigonometric functions.

[0110] As an example, the output signals of two Hall sensors are obtained, which are respectively denoted as HA and HB, and the output signals of the two sensors are orthogonal, such as Figure 6 As shown, the inverse tangent function is directly used for angle analysis to obtain the motor electrical angle β that satisfies:

[0111] β = arctan (HAHB).

[0112] As another example, the output signals of two Hall sensors are obtained, which are denoted as HC and HD, respectively, and the output signals of the two sensors are not orthogonal. Figure 7 As shown, the angle θ between the two sensors and the motor shaft is known (determined based on the setting position of the motor control chip 2), and the value of the angle θ can be configured by a register; Figure 8 As shown, by solving trigonometric functions, vectors HE and HF orthogonal to HD are constructed, and the angle η is the same as the angle θ, then:

[0113] HE = HF-EF;

[0114] EF = HDtanη = HDtanθ;

[0115] HF = HCsinη = HCsinθ;

[0116] Therefore, HE = HCsinη - HDtanη;

[0117] It can be obtained that the motor electrical angle β satisfies:

[0118] It should be noted that in actual use, different trigonometric functions can be constructed as needed to obtain the motor electrical angle β, which is not limited to the present embodiment. When the output signals of three or more Hall sensors are obtained, the output signals of any two Hall sensors can be calculated to obtain a motor electrical angle (analysis result), and the accuracy of the detection can be improved by averaging or correcting the analytical results. Specifically, in theory, the values ​​of the electrical angles of each motor should be equal, but in practical applications, due to measurement errors and calculation errors, there will inevitably be differences in the calculated values ​​of the electrical angles of each motor. The error can be weakened by averaging the electrical angles of each motor; the accuracy of the detection can also be judged by the difference in the calculated values ​​of the electrical angles of each motor. Once the difference is large (greater than the preset amount), it is considered that the detection is inaccurate and needs to be adjusted and re-detected. Any function implemented by redundant items is applicable to the present invention and will not be described one by one here.

[0119] 5) Based on the motor electrical angle β calculated in step 4), the rotor position is obtained, and a low-speed magnetic field oriented control algorithm is implemented in combination with vector control to control the motor operation, and then step 6) is executed.

[0120] Specifically, the low-speed magnetic field oriented control algorithm obtains the position of the rotor based on the analytical results, and then realizes the motor control. As an example, the low-speed magnetic field oriented control algorithm includes: collecting two-phase current; obtaining two-axis orthogonal current after Clarke transformation; obtaining orthogonal currents Id and Iq after rotation transformation, wherein Iq is related to torque and Id is related to magnetic flux; sending the currents Iq and Id to the PI regulator respectively to obtain the corresponding outputs Vq and Vd; obtaining the motor electrical angle (i.e., the angle rotated by the motor) calculated by the sensor output signal; performing an inverse park transformation to obtain two-axis voltages Va and Vb; performing an inverse Clarke transformation on the voltages Va and Vb to obtain the three-phase voltage actually required. In actual use, any FOC algorithm that determines the rotor position based on the output signal of the sensor is applicable to the present invention, and is not limited to this embodiment.

[0121] 6) Monitor the motor speed in real time. If the motor speed is greater than or equal to the high-speed threshold, execute step 7); if the motor speed is less than the high-speed threshold, execute step 5).

[0122] 7) Execute the sensorless field-oriented control algorithm, and then execute step 8); at this time, the rotor position is determined based on the collected phase current and voltage, without the need to obtain position information through sensors. The other calculation steps are similar to the low-speed field-oriented control algorithm and are not described in detail here.

[0123] 8) Monitor the motor speed in real time. If the motor speed is less than or equal to the low speed threshold, execute step 5); if the motor speed is greater than the low speed threshold, execute step 7).

[0124] It should be noted that the present invention obtains the rotor position through the sensor detection result at low speed (including zero speed), and realizes motor vector control based on the FOC algorithm, which can greatly simplify the algorithm and improve the control accuracy and stability of the motor at low speed; and adopts the FOC algorithm without position sensor at high speed to avoid errors caused by problems such as sensor sampling, conversion, and accuracy, and improve the control accuracy and stability of the motor at high speed. The motor control system and method of the present invention switches the control algorithm according to the motor speed, taking into account the advantages of the low-speed magnetic field oriented control algorithm with position sensor and the magnetic field oriented control algorithm without position sensor, so as to realize more stable and reliable motor control.

[0125] In summary, the present invention provides a motor control chip, system and method, including: a motor drive control circuit and at least two sensors; each sensor is arranged in sequence and spaced apart, and is used to detect the magnetic field to be measured and generate corresponding electrical signals respectively; at least two sensors are at equal distances from the motor shaft, and the angle between the two outermost sensors and the motor shaft is not greater than half of the electrical cycle of the motor; the motor drive control circuit receives the output signals of each sensor, and generates a motor drive signal based on the output signals of each sensor. The motor control chip of the present invention integrates the sensor into the chip, which greatly reduces the volume and cost of the motor control circuit. The motor control chip, system and method of the present invention switch the control algorithm according to the motor speed, adopt a low-speed magnetic field oriented control algorithm with a position sensor at low speed, and adopt a magnetic field oriented control algorithm without a position sensor at high speed, taking into account the advantages of the low-speed magnetic field oriented control algorithm and the magnetic field oriented control algorithm without a position sensor, and realizing more stable and reliable motor control. Therefore, the present invention effectively overcomes various shortcomings in the prior art and has a high industrial utilization value.

[0126] The above embodiments are merely illustrative of the principles and effects of the present invention, and are not intended to limit the present invention. Anyone familiar with the art may modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by a person of ordinary skill in the art without departing from the spirit and technical concept disclosed by the present invention shall still be covered by the claims of the present invention.

Claims

1. A motor control chip for controlling a three-phase brushless DC motor, characterized in that: The motor control chip comprises: a motor drive control circuit and at least two sensors; The sensors are arranged in sequence and spaced apart to detect the magnetic field to be measured and generate corresponding electrical signals respectively; at least two sensors are at equal distances from the motor shaft, and the angle between the two outermost sensors and the motor shaft is no greater than half of the electrical period of the motor; The motor drive control circuit receives the output signals of each sensor and generates a motor drive signal based on the output signals of each sensor; the motor drive control circuit obtains the motor electrical angle based on the following relationship: Wherein, β is the electrical angle of the motor; θ is the angle between the two outermost sensors and the motor shaft; HC and HD are the output signals of the two outermost sensors respectively.

2. The motor control chip according to claim 1, characterized in that: The distances from each sensor to the motor shaft are equal.

3. The motor control chip according to claim 1 or 2, characterized in that: The angle between the two sensors and the motor shaft is one quarter of the electrical cycle.

4. The motor control chip according to claim 1, characterized in that: The sensor is a Hall sensor, an anisotropic magnetoresistive sensor or a tunnel magnetoresistive sensor.

5. The motor control chip according to claim 1, characterized in that: The motor drive control circuit includes a current detection unit, an analog-to-digital converter, a control logic unit, a pre-drive unit and a power unit; The current detection unit detects the phase current of the motor; The analog-to-digital converter is connected to the output end of the current detection unit and each sensor, and is used to perform analog-to-digital conversion on the output signal of the current detection unit and the output signal of each sensor; The control logic unit is connected to the output end of the analog-to-digital converter and generates a motor control signal based on the output signal of the analog-to-digital converter; The pre-driving unit is connected to the output end of the control logic unit and generates a pre-driving signal based on the motor control signal; The power unit is controlled by the pre-driving signal to generate the motor driving signal.

6. The motor control chip according to claim 5, characterized in that: When the motor is running at a low speed, the control logic unit executes a low-speed magnetic field oriented control algorithm based on the output signals of each sensor and the output signal of the current detection unit to generate a corresponding motor control signal; when the motor is running at a high speed, the control logic unit executes a position sensorless magnetic field oriented control algorithm based on the output signal of the current detection unit to generate a corresponding motor control signal.

7. A motor control system, characterized in that: The motor control system at least comprises: A circuit board, a three-phase brushless DC motor, and a motor control chip as claimed in any one of claims 1 to 6; The three-phase brushless DC motor comprises a stator and a rotor coaxially arranged along the motor shaft, the circuit board is fixed on the stator of the three-phase brushless DC motor, and the plane where the circuit board is located is perpendicular to the axial direction of the three-phase brushless DC motor; The motor control chip is arranged on the circuit board, and is used for detecting the magnetic field and phase current of the three-phase brushless DC motor, and generating a motor driving signal based on the detected signal to control the operation of the three-phase brushless DC motor.

8. The motor control system according to claim 7, characterized in that: Each sensor on the motor control chip covers the gap between the stator and the rotor.

9. The motor control system according to claim 7, characterized in that: The circuit board is a circular structure, the circuit board is coaxially arranged with the stator and the rotor, and the radius of the circuit board is greater than the radius of the stator and the rotor.

10. A motor control method, implemented based on the motor control system according to any one of claims 7 to 9, characterized in that: The motor control method comprises: After power-on or receiving a start command, the initial speed of the motor is obtained. If the initial speed is less than a preset value, the motor is controlled based on a low-speed magnetic field oriented control algorithm; if the initial speed is greater than or equal to the preset value, the motor is controlled based on a position sensorless magnetic field oriented control algorithm; During the execution of the low-speed magnetic field oriented control algorithm, if the motor speed is greater than or equal to the high-speed threshold, switch to the magnetic field oriented control algorithm without position sensor; otherwise, continue to execute the low-speed magnetic field oriented control algorithm; During the execution of the sensorless magnetic field oriented control algorithm, if the motor speed is less than or equal to the low speed threshold, switching to the low speed magnetic field oriented control algorithm; otherwise, continuing to execute the sensorless magnetic field oriented control algorithm; The high-speed threshold is greater than the low-speed threshold.

11. The motor control method according to claim 10, characterized in that: The output signals of each sensor are analyzed based on trigonometric functions, and the low-speed magnetic field oriented control algorithm obtains the position of the rotor based on the analysis results, thereby realizing motor control.

12. The motor control method according to claim 11, characterized in that: When the motor control chip includes at least three sensors, the output signals of any two sensors obtain an analysis result, and the analysis results are averaged or corrected.

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