[0036] In order to make the objectives, technical solutions and advantages of the present invention clearer, the following further describes the present invention in detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention, but not to limit the present invention.
[0037] See Figure 1 to Figure 4 , The present invention is a positionless permanent magnet brushless DC motor control device, which cooperates with the motor and includes: a rotational speed setting module 100 and a motor control module 200 connected to each other;
[0038] The rotational speed setting module 100 is used to set predetermined rotational speed data of the motor;
[0039] The motor control module 200 is connected to the three phase wires of the motor, and includes: a back electromotive force collector 201, a signal processor 202, a signal comparator 203 and a motor driver 204;
[0040] The back-EMF collector 201 is used to collect the back-EMF on the motor to obtain three groups of back-EMF electrical signals;
[0041] The signal processor 202 is connected to the back-EMF collector 201, and is used to arrange all the back-EMF signals collected at the same time in a predetermined order to obtain a position signal, and each of the position signals is equal to Corresponds to the only rotor movement area;
[0042] The signal comparator 203 is connected to the signal processor 202, and is used to receive the position signal sent by the signal processor 202, and perform statistics on all the position signals within a predetermined period of time to obtain the actual speed data, and then calculate the actual speed. The speed data is compared with the predetermined speed data. If the comparison result is inconsistent, the drive signal is obtained according to the comparison result;
[0043] The motor driver 204 is connected to the signal comparator 203 for driving and controlling the motor according to the driving signal.
[0044] According to the electric balance formula: U=I*R1+E;
[0045] Where E=K*w; (K is a constant, determined by the motor. W is the angular velocity of the motor.)
[0046] Te=K1*I; (K1 is a constant, determined by the motor. Te is the electromagnetic torque of the motor.)
[0047] Te-TL= K2*W’; (K2 is a constant, determined by the motor and load. TL is the load torque, W’ is the angular acceleration.)
[0048] The control method proposed in this scheme is: when the set speed is greater than the actual motor speed, an instruction to increase the current I is issued, and when it is determined that the current current value is less than the current value required by the current instruction, an instruction to increase the voltage U is issued. The chopping duty cycle increases accordingly. Because the motor speed cannot change suddenly, the motor back electromotive force E cannot change suddenly, so I will increase, and Te will increase, which will break the balance and generate angular acceleration to increase the motor speed. Conversely, when the actual motor speed is greater than the set speed, the current will be required to weaken the current, generate a negative angular acceleration, so that the motor speed will be reduced, and such continuous adjustment will eventually stabilize the speed at the set speed.
[0049] The above-mentioned control flow can be simplified as follows: when the set speed is greater than the actual motor speed, a command to increase the voltage U is issued. The chopping duty cycle increases accordingly. Because the motor speed cannot change suddenly, the motor back electromotive force E cannot change suddenly, so I will increase, and Te will increase, which will break the balance and generate angular acceleration to increase the motor speed. Conversely, when the actual motor speed is greater than the set speed, the command to reduce the voltage U is issued, which produces a negative angular acceleration, which reduces the motor speed. This continuous adjustment will eventually stabilize the speed at the set speed.
[0050] Further, the motor driver 204 includes: six-way three-bridge inverters;
[0051] The six input ends of the six three-bridge inverters are all connected to the control chip in the signal comparator 203, and the three output ends are all connected to the three phase wires of the motor.
[0052] Among them, the six-way three-bridge inverter includes: six MOS tubes, which are respectively controlled by UH, UL, VH, VL, WH, WL, where POWEER_U is connected to the U line end of the motor, POWEER_V is connected to the V line end of the motor, and POWEER_W Connect to the W terminal of the motor. The six terminals UH, UL, VH, VL, WH, and WL are all controlled and input by the signal comparator 203.
[0053] Further, the back-EMF collector 201 includes: a voltage adjustment unit that compares the collected back-EMF voltage with a preset voltage value, if the collected back-EMF voltage is higher than the preset voltage value , The current back-EMF electrical signal is defined as a high-voltage signal, and the output signal is 1; if the collected back-EMF voltage is lower than the preset voltage value, the current back-EMF electrical signal is defined as a low-voltage signal, and the output signal Is 0.
[0054] The three back-EMF electrical signals are formed into a binary number in a predetermined order, and then in the order, they are 101, 100, 110, 010, 011, 001, and converted to decimal is 5, 4, 6, 2, 3, 1. This value is called the Hall value. Because the rotation range of the motor rotor has been divided into 6 moving areas in the early stage, each moving area corresponds to a range of 60°; each Hall value corresponds to a moving area, such as: Hall When the value is 1, it corresponds to the range of 0°-59°, and when the Hall value is 2, it corresponds to the range of 60°-119°. Therefore, by obtaining the Hall value, you can know the area where the rotor is located, and the Hall value can be used as a position signal.
[0055] See Figure 5 , The present invention is a control method applying the control device of the positionless permanent magnet brushless DC motor as described above, including:
[0056] 501. Set the predetermined speed
[0057] Set the motor's predetermined speed data. When applied to the sewing machine field, the pedal can be used to set the predetermined speed.
[0058] 502. Collect back-EMF electrical signals
[0059] Collect the back-EMF on the motor, and compare the voltage value of the back-EMF collected on each motor phase terminal with the preset voltage value, if the collected back-EMF voltage is higher than the preset voltage value , The current back-EMF electrical signal is defined as a high voltage signal; if the collected back-EMF voltage is lower than the preset voltage value, the current back-EMF electrical signal is defined as a low voltage signal; three groups of back-EMF electrical signals are obtained .
[0060] It is specifically as follows: Obtain the three-way back EMF from the phase lines U, V, and W of the motor, and compare the collected voltage value of the back EMF with the preset voltage value. If the collected back EMF voltage is higher than the preset voltage value, If the voltage value is set, the current back-EMF electrical signal is defined as a high voltage signal, and the output signal is 1; if the collected back-EMF voltage is lower than the preset voltage value, the current back-EMF electrical signal is defined as a low voltage signal , The output signal is 0.
[0061] 503. Calculate the actual speed
[0062] Arrange all the back-EMF electrical signals collected at the same time in a predetermined order to obtain position signals, and each of the position signals corresponds to a unique rotor movement area;
[0063] Then statistics of all position signals within a predetermined period of time are performed to obtain actual speed data.
[0064] It is specifically: according to the predetermined sequence U, V, W, three back-EMF electrical signals are formed into a binary number, which are 101, 100, 110, 010, 011, 001, and converted to decimal is 5, 4, 6 , 2, 3, 1, this value is called the Hall value. Since the rotation range of the motor rotor has been divided into 6 moving areas in the early stage, each moving area corresponds to a range of 60°; each Hall value is associated with a moving Corresponding to the area, such as: when the Hall value is 1, it corresponds to the range of 0°-59°, when the Hall value is 2, it corresponds to the range of 60°-119°, etc.; therefore, by obtaining the Hall value, you can know the area where the rotor is. Hall value as position signal;
[0065] After the Hall value is known, the rotor speed can be calculated by counting the number of areas the rotor enters within a predetermined period of time. For example, in 10S, the rotor has passed 3 moving areas, that is, its speed is: 3*60 /10=18 degrees/second.
[0066] 504. Determine the size between the speeds
[0067] The actual speed data is compared with the predetermined speed data to determine the size between the predetermined speed data and the actual speed data.
[0068] 505. Control motor acceleration
[0069] If the predetermined speed data is greater than the actual speed data, issue an instruction to increase the voltage to the motor; or, first issue an instruction to increase the current to the motor, and at the same time collect the current value of the current on the motor, and determine whether it is less than the increased current If the current value required in the instruction is less than that, an instruction to increase the voltage is issued to the motor;
[0070] According to the electric balance formula: U=I*R1+E;
[0071] Where E=K*w; (K is a constant, determined by the motor. W is the angular velocity of the motor.)
[0072] Te=K1*I; (K1 is a constant, determined by the motor. Te is the electromagnetic torque of the motor.)
[0073] Te-TL= K2*W’; (K2 is a constant, determined by the motor and load. TL is the load torque, W’ is the angular acceleration.)
[0074] Send an instruction to increase the voltage U to the motor, so that the chopping duty cycle increases accordingly. Because the motor speed cannot change suddenly, the motor back electromotive force E cannot change suddenly, so I will increase, and Te will increase, which will break the balance and generate angular acceleration to increase the motor speed.
[0075] First issue an instruction to increase the current I to the motor, and at the same time collect the current value of the current on the motor, and determine whether it is less than the current value required in the instruction to increase the current. If it is less, then issue an increase in voltage U to the motor Command; causes the chopping duty cycle to increase accordingly. Because the motor speed cannot change suddenly, the motor back electromotive force E cannot change suddenly, so I will increase, and Te will increase, which will break the balance and generate angular acceleration to increase the motor speed.
[0076] 506. Control motor deceleration
[0077] If the predetermined speed data is less than the actual speed data, send a command to reduce the voltage U to the motor; to generate a negative angular acceleration to reduce the motor speed, or send a command to reduce the current I to the motor to generate a negative angular acceleration To reduce the motor speed.
[0078] 507. Maintain the current speed
[0079] If the comparison result is consistent, no adjustment control is made to the running speed of the motor.
[0080] 508. Motor execution drive
[0081] According to the received instruction, the motor executes the correspondingly adjusted drive action; when no new instruction is received, it keeps performing the existing drive action, and after executing the drive action, returns to step 502. Collect the back-EMF electric signal .
[0082] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modification, equivalent replacement and improvement made within the spirit and principle of the present invention shall be included in the protection of the present invention. Within range.
