Driving control method and driving control circuit of non-inductive three-phase brushless motor

Abstract

The embodiment of the invention provides a driving control method and a driving control circuit of a non-inductive three-phase brushless motor. The driving control method of the non-inductive three-phase brushless motor comprises the following steps: S1, obtaining a back electromotive force curve of the motor based on obtained U-phase voltage, V-phase voltage and U-phase current; s2, based on the obtained back electromotive force curve of the motor, obtaining an electrical period of the motor and a real-time rotation speed of the motor; s3, obtaining an estimated rotor position based on the obtained back electromotive force curve and the lead angle of the motor; s4, adjusting a speed control instruction of the motor based on the obtained real-time rotation speed of the motor and the specified input speed; and S5, calculating the three-phase voltage based on the estimated rotor position and the adjusted speed control instruction of the motor. The technical problem of lack of low-cost electronic speed stability control is solved, and compared with the technical scheme adopting complex software and hardware, the technical effects of economy, simplicity and accuracy are achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of motor drive, and in particular to a drive control method and a drive control circuit for a sensorless three-phase brushless motor. Background Art

[0002] In the existing three-phase brushless speed stabilization system, the rotor position is generally fed back into the speed control closed-loop system using Hall sensors for sensored three-phase brushless control. However, the Hall sensor increases the hardware cost of the system. In addition, other solutions also use the field-oriented control (FOC) algorithm to estimate and correct the rotor position for sensorless control. Similarly, this also brings higher costs to the system, such as higher-performance hardware and more computing resources. Therefore, an economical and accurate motor drive control method is needed. Summary of the invention

[0003] In view of the deficiencies in the prior art, the present invention provides a drive control method and a drive control circuit for a sensorless three-phase brushless motor, which solve the technical problems of complex structure and high cost in the prior art.

[0004] In the first aspect, according to an embodiment of the present invention, a drive control method for a three-phase brushless motor is proposed, comprising the following steps: S1, obtaining the back electromotive force curve of the motor based on the acquired U-phase voltage, V-phase voltage and U-phase current; S2, obtaining the electrical period of the motor and the real-time rotation speed of the motor based on the obtained back electromotive force curve of the motor; S3, obtaining the estimated rotor position based on the obtained back electromotive force curve and the lead angle of the motor; S4, adjusting the speed control instruction of the motor based on the obtained real-time rotation speed of the motor and the specified input speed; S5, calculating the three-phase voltage based on the estimated rotor position and the adjusted speed control instruction of the motor.

[0005] According to an embodiment of the present invention, any back electromotive force on the back electromotive force curve is obtained by subtracting the U-phase current multiplied by the U-phase resistance from the relative phase voltage of the U-phase voltage relative to the V-phase voltage.

[0006] According to an embodiment of the present invention, any back electromotive force is:

[0007] BEMF1=Vu-v–Iu×Rum*Kc,

[0008] Among them, Vu-v is the relative phase voltage of U phase voltage relative to V phase voltage, Iu is the U phase current, Rum is the U phase resistance, and Kc is a constant.

[0009] According to an embodiment of the present invention, the electrical period of the motor is obtained based on the time difference between the zero crossing points of the back electromotive force curve.

[0010] According to an embodiment of the present invention, the real-time rotation speed of the motor is obtained based on the electrical cycle of the motor.

[0011] According to an embodiment of the present invention, the estimated zero-phase point of the rotor position is the sum of the zero-crossing point and the lead angle of the back electromotive force curve of the motor.

[0012] According to an embodiment of the present invention, the estimated real-time position of the rotor position is obtained based on the electrical cycle of the motor and the 0-phase point.

[0013] According to an embodiment of the present invention, the speed control instruction of the motor is a ratio of the pulse width modulation output voltage to the power supply voltage.

[0014] According to an embodiment of the present invention, the initial value of the speed control instruction of the motor is:

[0015] SpeedCmd_ini=(BEMF2+Vstart)*Kg / VCC,

[0016] Among them, Vstart is the starting voltage, Kg is the inherent parameter, VCC is the power supply voltage, and the effective value voltage BEMF2 of the back electromotive force is:

[0017] BEMF2=Ke*Speed,

[0018] Among them, Ke is the back electromotive force constant, and Speed ​​is the real-time rotation speed of the motor.

[0019] In a second aspect, according to another embodiment of the present invention, a drive control circuit is provided, which drives the motor by using the drive control method of a sensorless three-phase brushless motor as described in the first aspect.

[0020] The technical principle of the present invention is: based on the back electromotive force curve of the motor, the electrical period of the motor and the real-time rotation speed of the motor are obtained to estimate the rotor position and calibrate the actual rotation speed, and three-phase voltage output is performed based on the estimated rotor position and the calibrated speed control instruction.

[0021] Compared with the prior art, the present invention has the following beneficial effects: it solves the problem of lack of low-cost electronic speed stabilization control technology by only observing the electromotive force of the motor and calculating the speed and rotor position of the motor, and produces an economical, simple and accurate technical effect compared with the technical solution adopting complex software and hardware. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 The figure is a flow chart of a drive control method of a sensorless three-phase brushless motor according to an embodiment of the present invention.

[0023] Figure 2Schematic diagram of the relationship between the rotor position and the back electromotive force curve according to an embodiment of the present invention.

[0024] Figure 3 It is a curve diagram of the change of the speed control instruction according to the embodiment of the present invention. DETAILED DESCRIPTION

[0025] The technical solution of the present invention is further described below in conjunction with the accompanying drawings and embodiments.

[0026] As the background technology, the existing technology has the technical problems of complex structure and high cost of motor drive control system. Figure 1 As shown, the embodiment of the present invention proposes a drive control method for a non-sensing three-phase brushless motor, comprising the following steps: S1, obtaining the back electromotive force curve of the motor based on the obtained U-phase voltage, V-phase voltage and U-phase current; S2, obtaining the electrical cycle of the motor and the real-time rotation speed of the motor based on the obtained back electromotive force curve of the motor; S3, obtaining the estimated rotor position based on the obtained back electromotive force curve and the lead angle of the motor; S4, adjusting the speed control instruction of the motor based on the obtained real-time rotation speed of the motor and the specified input speed; S5, calculating the three-phase voltage based on the estimated rotor position and the adjusted speed control instruction of the motor. The electrical cycle of the motor and the real-time rotation speed of the motor are obtained based on the back electromotive force curve of the motor, so as to estimate the rotor position and calibrate the actual rotation speed, and output the three-phase voltage based on the estimated rotor position and the calibrated speed control instruction. Only by observing the electromotive force of the motor and calculating the speed and rotor position of the motor, it solves the problem of lack of low-cost electronic speed stability control technology, and produces economical, simple and accurate technical effects compared with the technical solutions of complex software and hardware.

[0027] According to an embodiment of the present invention, any back electromotive force on the back electromotive force curve is obtained by subtracting the U-phase current multiplied by the U-phase resistance from the relative phase voltage of the U-phase voltage relative to the V-phase voltage. In a brushless DC motor (BLDC), a back electromotive force is generated when current passes through the motor winding. The back electromotive force curve (BEMF1) can be used to calculate the rotor position. This formula is not directly equal to the back electromotive force voltage, but can be used to describe the change state of the back electromotive force of the motor.

[0028] In addition, in order to make the back electromotive force curve closer to the actual back electromotive force voltage, a parameter Kc is introduced for correction. According to an embodiment of the present invention, any back electromotive force is:

[0029] BEMF1=Vu-v–Iu×Rum*Kc,

[0030] Among them, Vu-v is the relative phase voltage of U phase voltage relative to V phase voltage, Iu is the U phase current, Rum is the U phase resistance, and Kc is a constant.

[0031] According to an embodiment of the present invention, the electrical cycle of the motor is obtained based on the time difference between the zero crossing points of the back electromotive force curve. In addition, the real-time rotation speed of the motor is obtained based on the electrical cycle of the motor.

[0032] According to an embodiment of the present invention, Figure 2 As shown, the 0-phase point of the estimated rotor position is the sum of the zero-crossing point and the lead angle of the back electromotive force curve of the motor. There is an inherent relationship between the back electromotive force zero-crossing point and the point where the estimated rotor position is equal to 0 phase, and this inherent relationship is the lead angle. The motor back electromotive force curve indicates the zero-crossing point, and the position of the point where the estimated rotor position is equal to 0 phase is corrected using the zero-crossing point and the preset lead angle. The position of the point where the estimated rotor position is equal to 0 phase is equal to the position of the back electromotive force zero-crossing point plus the angle of the lead angle.

[0033] According to an embodiment of the present invention, the estimated real-time position of the rotor position is obtained based on the electrical cycle of the motor and the 0-phase point. The new electrical cycle uses the 0-phase point as the initial phase, and combines the electrical cycle of the motor rotation to obtain the real-time position of the rotor position. In addition, the initial phase is corrected for each electrical cycle, so that the estimated rotor position is closer to the actual rotor position.

[0034] According to an embodiment of the present invention, the speed control instruction of the motor is the ratio of the pulse width modulation output voltage to the power supply voltage. The speed instruction actually used by the motor is compared with the input speed instruction, and the (actual) speed control instruction is adjusted according to the comparison result. If the actual speed is greater than the input speed, the speed control instruction is reduced. If the speed control instruction is less than the input speed, the speed control instruction is increased. Finally, the actual speed is consistent with the input speed instruction, and the motor rotates stably. The change process is as follows: Figure 3 In addition, the parameter Kt is introduced to control the actual speed change rate, which can make the speed change smoother and make the system more stable.

[0035] According to an embodiment of the present invention, the initial value of the actual speed command is also related to the stability of the motor speed. The initial value of the speed control command actually used is related to the power supply voltage, the back electromotive force voltage after the motor is started, and the starting voltage, and the set speed command value is continuously approached on the basis of this value. The initial value of the motor speed control command is:

[0036] SpeedCmd_ini=(BEMF2+Vstart)*Kg / VCC,

[0037] Among them, Vstart is the starting voltage, Kg is the inherent parameter, VCC is the power supply voltage, and the effective value voltage BEMF2 of the back electromotive force is:

[0038] BEMF2=Ke*Speed,

[0039] Among them, Ke is the back electromotive force constant, and Speed ​​is the real-time rotation speed of the motor.

[0040] According to another embodiment of the present invention, a drive control circuit is provided, which drives the motor by using the drive control method of a sensorless three-phase brushless motor as described above.

[0041] As described above, the embodiment of the present invention can obtain accurate rotor position and stable speed control instructions for actual use, that is, accurate instantaneous position and stable real-time output voltage amplitude, thereby achieving stable motor rotation speed.

[0042] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the purpose and scope of the technical solution of the present invention, which should be included in the scope of the claims of the present invention.

Claims

1. A drive control method for a sensorless three-phase brushless motor, characterized in that: The following steps are involved: S1, obtaining a back electromotive force curve of the motor based on the acquired U-phase voltage, V-phase voltage and U-phase current; S2. obtaining the electrical cycle of the motor and the real-time rotation speed of the motor based on the obtained back electromotive force curve of the motor; S3, obtaining an estimated rotor position based on the obtained back electromotive force curve and lead angle of the motor; S4, adjusting the speed control instruction of the motor based on the obtained real-time rotation speed of the motor and the specified input speed; S5. Calculate the three-phase voltage based on the estimated rotor position and the adjusted speed control command of the motor.

2. A drive control method for a sensorless three-phase brushless motor as claimed in claim 1, characterized in that: Any back electromotive force on the back electromotive force curve is obtained by subtracting the U phase current multiplied by the U phase resistance from the relative phase voltage of the U phase voltage relative to the V phase voltage.

3. The drive control method of a sensorless three-phase brushless motor as claimed in claim 2, characterized in that: Any back EMF is: BEMF1=Vu-v–Iu×Rum*Kc, Among them, Vu-v is the relative phase voltage of U phase voltage relative to V phase voltage, Iu is the U phase current, Rum is the U phase resistance, and Kc is a constant.

4. The drive control method of a sensorless three-phase brushless motor as claimed in claim 1, characterized in that: The electrical period of the motor is obtained based on the time difference between the zero crossings of the back EMF curve.

5. The drive control method of a sensorless three-phase brushless motor as claimed in claim 4, characterized in that: The real-time rotation speed of the motor is obtained based on the electrical cycle of the motor.

6. The drive control method of a sensorless three-phase brushless motor according to claim 1, characterized in that: The 0-phase point of the estimated rotor position is the sum of the zero-crossing point and the lead angle of the back electromotive force curve of the motor.

7. A drive control method for a sensorless three-phase brushless motor as claimed in claim 6, characterized in that: The estimated real-time position of the rotor position is obtained based on the electrical cycle of the motor and the 0-phase point.

8. The drive control method of a sensorless three-phase brushless motor as claimed in claim 1, characterized in that: The speed control command of the motor is the ratio of the pulse width modulation output voltage to the power supply voltage.

9. A drive control method for a sensorless three-phase brushless motor as claimed in claim 8, characterized in that: The initial value of the motor speed control command is: SpeedCmd_ini=(BEMF2+Vstart)*Kg / VCC, Among them, Vstart is the starting voltage, Kg is the inherent parameter, VCC is the power supply voltage, and the effective value voltage BEMF2 of the back electromotive force is: BEMF2=Ke*Speed, Among them, Ke is the back electromotive force constant, and Speed ​​is the real-time rotation speed of the motor.

10. A drive control circuit, characterized in that: The motor is driven by using a drive control method for a sensorless three-phase brushless motor as described in any one of claims 1 to 9.

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