CN109905059B - Sensorless direct current brushless motor control method and device - Google Patents
Sensorless direct current brushless motor control method and device Download PDFInfo
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Abstract
The invention provides a control method and a device of a sensorless direct current brushless motor, wherein the method comprises the following steps: connecting the sensorless direct-current brushless motor with the three-phase output of the driving circuit in a star connection mode; collecting a first voltage value output by three phases of the driving circuit and collecting a second voltage value of a middle point of the star connection every time a preset time interval passes; determining a current level signal corresponding to the current time interval according to the first voltage value and the second voltage value; judging whether the number of time intervals corresponding to the current level signal is greater than a reference number; if the number of the time intervals corresponding to the current level signal is larger than the reference number, determining the level signal which is overturned next time as a real position change signal; and after the real position change signal is obtained, switching signals of the driving circuit are inverted. The scheme can improve the accuracy of controlling the sensorless direct current brushless motor.
Description
Technical Field
The invention relates to the technical field of electrical engineering, in particular to a control method and a control device of a sensorless direct current brushless motor.
Background
With the rapid development of power electronic devices and control theories, the permanent magnet brushless dc motor is widely used due to its high efficiency, good speed regulation and easy maintenance. The conventional permanent magnet brushless direct current motor adopts a position sensor to determine the position of a rotor, and the sensorless brushless direct current motor needs to detect the position of the rotor according to stator current or stator voltage in a winding.
When the rotor position of the brushless DC motor is detected according to the stator current or the stator voltage in the winding, because a power switch device is used in a driving circuit of the brushless DC motor, the brushless DC motor can generate larger voltage spike interference at the end voltage of the three-phase winding when working, so that the line back electromotive force signal generates voltage spike interference, and the rotor position detection is wrong.
At present, in order to avoid the influence of voltage spike interference on the control of the sensorless brushless dc motor, a filter circuit is usually added in the circuit, and the voltage spike interference generated by the power switch device is eliminated through the filter circuit.
Although the filter circuit is added in the circuit to eliminate the voltage spike interference, the filter circuit can delay the normal position signal, so that the rotor position detection precision is low, and the accuracy of controlling the sensorless brushless direct-current motor is poor.
Disclosure of Invention
The embodiment of the invention provides a method and a device for controlling a sensorless direct current brushless motor, which can improve the accuracy of controlling the sensorless direct current brushless motor.
In a first aspect, an embodiment of the present invention provides a sensorless dc brushless motor control method, including:
connecting the sensorless direct-current brushless motor with the three-phase output of the driving circuit in a star connection mode;
collecting a first voltage value output by three phases of the driving circuit and collecting a second voltage value of the middle point of the star connection every time a preset time interval passes;
determining a current level signal corresponding to a current time interval according to the first voltage value and the second voltage value;
judging whether the number of the time intervals corresponding to the current level signal is larger than a reference number, wherein the reference number is determined according to a level overturning period corresponding to a previous level signal before the sensorless brushless direct current motor is overturned to the current level signal;
if the number of the time intervals corresponding to the current level signal is larger than the reference number, determining that the level signal which is overturned next time is a real position change signal;
and after the real position change signal is obtained, turning over a switching signal of the driving circuit.
Optionally, the driving circuit comprises: the MOS transistor comprises a control chip, a first MOS transistor, a second MOS transistor, a third MOS transistor, a fourth MOS transistor, a fifth MOS transistor and a sixth MOS transistor;
the drain electrodes of the first MOS tube, the third MOS tube and the fifth MOS tube are all connected with an external direct-current power supply;
the source electrodes of the second MOS tube, the fourth MOS tube and the sixth MOS tube are all grounded;
the source electrode of the first MOS tube is connected with the drain electrode of the second MOS tube, the source electrode of the third MOS tube is connected with the drain electrode of the fourth MOS tube, and the source electrode of the fifth MOS tube is connected with the drain electrode of the sixth MOS tube;
the source electrode of the first MOS tube is connected with a U-phase winding voltage input end of the sensorless direct-current brushless motor, the source electrode of the third MOS tube is connected with a V-phase voltage input end of the sensorless direct-current brushless motor, and the source electrode of the fifth MOS tube is connected with a W-phase voltage input end of the sensorless direct-current brushless motor;
the gates of the first MOS tube and the second MOS tube are respectively connected with two U-phase control pins on the control chip, the gates of the third MOS tube and the fourth MOS tube are respectively connected with two V-phase control pins on the control chip, and the gates of the fifth MOS tube and the sixth MOS tube are respectively connected with two W-phase control pins on the control chip;
the control chip is used for sending switching signals to the first MOS tube, the second MOS tube, the third MOS tube, the fourth MOS tube, the fifth MOS tube and the sixth MOS tube.
Optionally, the determining a current level signal corresponding to a current time interval according to the first voltage value and the second voltage value includes:
comparing the U-phase voltage value included in the first voltage value with the second voltage value to obtain a U-phase level;
comparing the voltage value of the V-phase included by the first voltage value with the second voltage value to obtain a V-phase level;
comparing the W-phase voltage value included in the first voltage value with the second voltage value to obtain a W-phase level;
determining the obtained U-phase level, V-phase level and W-phase level as the current level signal.
Optionally, the determining whether the number of the time intervals corresponding to the current level signal is greater than a reference number includes:
s1: after the current level signal is determined, adding 1 to a counter;
s2: acquiring a level overturning period corresponding to a previous level signal before the current level signal is overturned;
s3: calculating the reference number corresponding to the current level signal according to a level flip period corresponding to the previous level signal by the following formula;
wherein, T isnCharacterizing the reference quantity corresponding to the current level signal; said t isn-1Representing a level turnover period corresponding to the previous level signal; the T iskCharacterizing a duration of the time interval; the sigma represents a coefficient determined according to the strength of voltage spike interference generated by the driving circuit, and 0< sigma < 1;
s4: determining whether the counter is greater than the reference number corresponding to the current level signal.
Optionally, after the inverting the switching signal of the driving circuit, the method further includes:
and clearing the counter to restart counting the number of the time intervals of the next level signal after the current level signal is overturned.
Optionally, the inverting the switching signal of the driving circuit includes:
determining a next level signal relative to the current level signal according to the turning rule of the level signal in the operation process of the sensorless direct current brushless motor;
and turning over a switching signal of the driving circuit according to the next level signal, so that the alternating current input by the driving circuit into the sensorless direct current brushless motor is matched with the rotor position of the sensorless direct current brushless motor.
In a second aspect, an embodiment of the present invention further provides a sensorless dc brushless motor control apparatus, including: the device comprises an acquisition unit, a processing unit, a judgment unit, a prediction unit and a control unit;
the acquisition unit is used for acquiring a first voltage value output by three phases of a driving circuit connected with the sensorless direct current brushless motor in a star connection mode every time a preset time interval passes, and acquiring a second voltage value of a middle point of the star connection;
the processing unit is used for determining a current level signal corresponding to a current time interval according to the first voltage value and the second voltage value acquired by the acquisition unit;
the judging unit is configured to judge whether the number of the time intervals corresponding to the current level signal determined by the processing unit is greater than a reference number, where the reference number is determined according to a level flipping period corresponding to a previous level signal before the sensorless dc brushless motor flips to the current level signal;
the prediction unit is used for determining that the next level signal which is overturned is a real position change signal if the number of the time intervals corresponding to the current level signal is larger than the reference number according to the judgment result of the judgment unit;
the control unit is used for inverting the switching signal of the driving circuit after the prediction unit determines that the level signal which is inverted next time is a real position change signal and obtains the real position change signal.
Optionally, the processing unit comprises: the integrated circuit comprises a first comparator, a second comparator, a third comparator and an integrated subunit;
the first comparator is used for comparing the U-phase voltage value included in the first voltage value with the second voltage value to obtain a U-phase level;
the second comparator is used for comparing the voltage value of the V-phase included by the first voltage value with the second voltage value to obtain a V-phase level;
the third comparator is used for comparing the W-phase voltage value included in the first voltage value with the second voltage value to obtain a W-phase level;
the integration subunit is configured to determine the U-phase level obtained by the first comparator, the V-phase level obtained by the second comparator, and the W-phase level obtained by the third comparator as the current level signal.
Optionally, the determining unit is configured to perform the following operations:
s1: after the current level signal is determined, adding 1 to a counter;
s2: acquiring a level overturning period corresponding to a previous level signal before the current level signal is overturned;
s3: calculating the reference number corresponding to the current level signal according to a level flip period corresponding to the previous level signal by the following formula;
wherein, T isnCharacterizing the reference quantity corresponding to the current level signal; said t isn-1Representing a level turnover period corresponding to the previous level signal; the T iskCharacterizing a duration of the time interval; the sigma represents a coefficient determined according to the strength of voltage spike interference generated by the driving circuit, and 0< sigma < 1;
s4: determining whether the counter is greater than the reference number corresponding to the current level signal.
Alternatively,
the judging unit is further configured to clear the counter after the switching signal of the driving circuit is inverted, so as to restart counting of the number of the time intervals that a next level signal passes after the current level signal is inverted.
The sensorless DC brushless motor control method and the device provided by the embodiment of the invention connect the sensorless DC brushless motor with the three-phase output of the driving circuit in a star connection mode, then collect a first voltage value of the three-phase output of the driving circuit and a second voltage value of the star connection midpoint once every preset time interval, further obtain a current level signal corresponding to the current time interval according to the collected first voltage value and second voltage value, then judge whether the number of the elapsed time intervals corresponding to the current level signal is larger than a reference number, the reference number is determined according to the level inversion period of the last level signal after the sensorless DC brushless motor is inverted into the current level signal, if the judgment result is that the number of the elapsed time intervals corresponding to the current level signal is larger than the reference number, determining that the level signal which is turned over next time is a real position change signal, taking the level signal which is turned over for the first time as the real position change signal, and turning over the switch signal of the driving circuit after the real position change signal is obtained. Therefore, the turning time of the current level signal is predicted according to the duration time of the last level signal aiming at each level signal reflecting the position of the rotor in the running process of the sensorless direct current brushless motor, so that the voltage spike interference generated by a power device in the level signal is filtered out, and the real position change signal is not detected to generate time delay due to the fact that a filter circuit is not used, so that the accuracy of controlling the sensorless direct current brushless motor can be improved.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to these drawings without creative efforts.
Fig. 1 is a flowchart of a sensorless dc brushless motor control method according to an embodiment of the present invention;
FIG. 2 is a schematic diagram of a driving circuit according to an embodiment of the present invention;
FIG. 3 is a schematic diagram of a star connection provided by one embodiment of the present invention;
FIG. 4 is a flow chart of a method for comparing a counter to a reference number according to an embodiment of the present invention;
fig. 5 is a schematic diagram of an apparatus in which a sensorless dc brushless motor control apparatus according to an embodiment of the present invention is located;
fig. 6 is a schematic diagram of a sensorless dc brushless motor control apparatus according to an embodiment of the present invention;
fig. 7 is a schematic diagram of another sensorless dc brushless motor control apparatus according to an embodiment of the present invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer and more complete, the technical solutions in the embodiments of the present invention will be described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, but not all, embodiments of the present invention, and based on the embodiments of the present invention, all other embodiments obtained by a person of ordinary skill in the art without creative efforts belong to the scope of the present invention.
As shown in fig. 1, an embodiment of the present invention provides a sensorless dc brushless motor control method, which may include the following steps:
step 101: connecting the sensorless direct-current brushless motor with the three-phase output of the driving circuit in a star connection mode;
step 102: collecting a first voltage value output by three phases of the driving circuit and collecting a second voltage value of a middle point of the star connection every time a preset time interval passes;
step 103: determining a current level signal corresponding to the current time interval according to the first voltage value and the second voltage value;
step 104: judging whether the number of time intervals corresponding to the current level signal is larger than a reference number, wherein the reference number is determined according to a level overturning period corresponding to a previous level signal after the sensorless direct-current brushless motor is overturned to the current level signal;
step 105: if the number of the time intervals corresponding to the current level signal is larger than the reference number, determining the level signal which is overturned next time as a real position change signal;
step 106: and after the real position change signal is obtained, switching signals of the driving circuit are inverted.
The sensorless DC brushless motor control method provided by the embodiment of the invention connects the sensorless DC brushless motor with the three-phase output of the driving circuit in a star connection mode, then collects a first voltage value of the three-phase output of the driving circuit and a second voltage value of a midpoint of the star connection once every preset time interval, further obtains a current level signal corresponding to the current time interval according to the collected first voltage value and second voltage value, then judges whether the number of the elapsed time intervals corresponding to the current level signal is greater than a reference number, the reference number is determined according to a level inversion period of a last level signal after the sensorless DC brushless motor is inverted into the current level signal, if the judgment result is that the number of the elapsed time intervals corresponding to the current level signal is greater than the reference number, determining that the level signal which is turned over next time is a real position change signal, taking the level signal which is turned over for the first time as the real position change signal, and turning over the switch signal of the driving circuit after the real position change signal is obtained. Therefore, the turning time of the current level signal is predicted according to the duration time of the last level signal aiming at each level signal reflecting the position of the rotor in the running process of the sensorless direct current brushless motor, so that the voltage spike interference generated by a power device in the level signal is filtered out, and the real position change signal is not detected to generate time delay due to the fact that a filter circuit is not used, so that the accuracy of controlling the sensorless direct current brushless motor can be improved.
In the embodiment of the present invention, when the rotor of the sensorless dc brushless motor rotates one revolution, the winding coil of the sensorless dc brushless motor will go through a plurality of electrical cycles, and each electrical cycle includes 6 level flipping cycles, and the 6 level flipping cycles correspond to 6 different level signals formed by U, V, W three-phase level combinations. In the case of a sensorless dc brushless motor with a uniform rotation speed, the duration of the 6 different level signals is equal, i.e. each level flipping period is equal to 1/6 of the electrical period. Since the embodiment of the present invention predicts the ending time of each level flipping period by counting the number of time intervals, the time duration of the time interval needs to be smaller than the time duration of the level flipping period, and to ensure the accuracy of the prediction, it is further necessary that each level flipping period includes a plurality of time intervals, for which the time interval should be much smaller than the level flipping period, for example, the time interval is equal to 1/1000 of the electrical period, and the time interval is equal to 3/500 of the level flipping period.
Alternatively, on the basis of the sensorless dc brushless motor control method shown in fig. 1, step 101 connects the sensorless dc brushless motor with the three-phase output of the driving circuit in a star connection manner, as shown in fig. 2, the driving circuit may include: the control chip comprises a first MOS transistor Q1, a second MOS transistor Q2, a third MOS transistor Q3, a fourth MOS transistor Q4, a fifth MOS transistor Q5 and a sixth MOS transistor Q6;
the drains of the first MOS transistor Q1, the third MOS transistor Q3 and the fifth MOS transistor Q5 are all connected with an external direct current power supply V _ bus;
the sources of the second MOS transistor Q2, the fourth MOS transistor Q4 and the sixth MOS transistor Q6 are all grounded;
the source electrode of the first MOS transistor Q1 is connected with the drain electrode of the second MOS transistor Q2, the source electrode of the third MOS transistor Q3 is connected with the drain electrode of the fourth MOS transistor Q4, and the source electrode of the fifth MOS transistor Q5 is connected with the drain electrode of the sixth MOS transistor Q6;
the source electrode of the first MOS tube Q1 is connected with a U-phase winding voltage input end U of the sensorless DC brushless motor, the source electrode of the third MOS tube Q3 is connected with a V-phase voltage input end V of the sensorless DC brushless motor, and the source electrode of the fifth MOS tube Q5 is connected with a W-phase voltage input end W of the sensorless DC brushless motor;
the gates of the first MOS tube Q1 and the second MOS tube Q2 are respectively connected with two U-phase control pins U _ up and U _ down on the control chip, the gates of the third MOS tube Q3 and the fourth MOS tube Q4 are respectively connected with two V-phase control pins V _ up and V _ down on the control chip, and the gates of the fifth MOS tube Q5 and the sixth MOS tube Q6 are respectively connected with two W-phase control pins W _ up and W _ down on the control chip;
the control chip is used for sending switching signals to the first MOS transistor Q1, the second MOS transistor Q2, the third MOS transistor Q3, the fourth MOS transistor Q4, the fifth MOS transistor Q5 and the sixth MOS transistor Q6.
In the embodiment of the invention, the control chip is respectively connected with the grid of each MOS tube, and after the real position change signal reflecting the real position of the rotor in the sensorless DC brushless motor is obtained, the control chip in the driving circuit can be sent with a corresponding instruction, so that the control chip can change the switch signal output to the grid of each MOS tube, and further the driving circuit inputs the voltage corresponding to the real position of the rotor to the sensorless DC brushless motor, thereby realizing the accurate control of the operation of the sensorless DC brushless motor.
In an embodiment of the present invention, the three-phase output U, V, W of the driving circuit is connected to the three-phase voltage input of the sensorless dc brushless motor in a star connection, as shown in fig. 3. The U-phase winding voltage input end U is connected with the source electrode of the first MOS transistor Q1, the V-phase voltage input end V is connected with the source electrode of the third MOS transistor Q3, and the W-phase voltage input end W is connected with the source electrode of the fifth MOS transistor Q5. In addition, a common point O of the U-phase winding voltage input terminal U, V phase voltage input terminal V and the W-phase voltage input terminal W is a midpoint of the star connection.
Alternatively, on the basis of the sensorless dc brushless motor control method shown in fig. 1, step 103 determines a current level signal corresponding to a current time interval according to a first voltage value and a second voltage value, and since the first voltage value includes a U-phase voltage value at a U-phase output terminal, a V-phase voltage value at a V-phase output terminal, and a W-phase voltage value at a W-phase output terminal on the driving circuit, the current level signal may be determined by comparing the U-phase voltage value, the V-phase voltage value, and the W-phase voltage value included in the first voltage value with the second voltage value, respectively.
Specifically, after a first voltage value and a second voltage value are acquired in a current time interval, a U-phase voltage value included in the first voltage value is compared with the second voltage value to obtain a U-phase level, a V-phase voltage value included in the first voltage value is compared with the second voltage value to obtain a V-phase level, a W-phase voltage value included in the first voltage value is compared with the second voltage value to obtain a W-phase level, and then a level sequence of a combination of the U-phase level, the V-phase level and the W-phase level is determined as a current level signal corresponding to the current time interval.
In the embodiment of the present invention, the three-phase outputs of the driving circuit are a U-phase output, a V-phase output and a W-phase output, respectively, and a high level or a low level can be obtained by comparing the voltage value of each phase output with the voltage value of the star connection midpoint according to the difference in potential of the three-phase outputs with respect to the star connection midpoint, but since the three levels corresponding to the three-phase outputs of the driving circuit cannot be simultaneously high level or simultaneously low level, the obtained level signals include 6 different forms, and the levels corresponding to U, V, W phases are sequentially high-low, high-low, high-low-high, low-high-low and low-high.
Alternatively, on the basis of the sensorless dc brushless motor control method shown in fig. 1, step 104 determines whether the number of time intervals corresponding to the current level signal is greater than a reference number, specifically, whether the number of time intervals during which the current level signal is inverted from the previous level signal is greater than the reference number, and the reference data is determined according to the number of time intervals during which the previous level signal is continued. As shown in fig. 4, the determination process may be specifically implemented as follows:
step 401: after the current level signal is determined, 1 is added to the counter.
Specifically, a counter Tc whose initial value is zero is set in advance, and 1 is added to the counter Tc after the level signal is acquired every time interval from the inversion of the level signal from the last level signal to the current signal.
For example, the level signal (U-phase-V-phase-W-phase) of the sensorless dc brushless motor is cyclically inverted in the following order: high-low, high-low, high-low-high, low-high-low, low-high. When the current level signal is high-low, the counter Tc corresponding to the current level signal is equal to zero when the level signal is just turned from high-low to high-low, 1 is added to the counter Tc after each time interval after the current level signal is turned, and the counter Tc is cleared until the level signal is turned from high-low to high-low-high.
Step 402: and acquiring a level overturning period corresponding to the last level signal before the level signal is overturned to the current level signal.
Specifically, since the previous level signal with respect to the current level signal has been inverted, the number of time intervals elapsed for the previous level signal is determined, and after the number of time intervals elapsed for the previous level signal is acquired, the product of the acquired number of time intervals and the time period of the time interval is calculated, and the level inversion period corresponding to the previous level signal is obtained.
For example, the predetermined time interval is 2 × 10-6And s. The current level signal is high-low, the last level signal relative to the current level signal is high-low, the number of time intervals that the last level signal passes through is determined to be 166 according to the value of a counter Tc before the level signal is turned from high-low to high-low, and the product of the number of acquired time intervals and the time length of the time intervals is calculated to be 166 multiplied by 2 multiplied by 10-6Equal to 3.32 × 10-4I.e. the periphery of the level transition corresponding to the last level signal is equal to 3.32 x 10-4s。
Step 403: and according to the level turnover period corresponding to the obtained last level signal, calculating the reference quantity corresponding to the current level signal by the following formula.
Specifically, after a level inversion period corresponding to a previous level signal for a current level signal is acquired, substituting the acquired level inversion period into the following formula to calculate a reference number corresponding to the current level signal;
wherein, TnCharacterizing a reference quantity corresponding to a current level signal; t is tn-1Representing a level overturning period corresponding to the previous level signal; t iskCharacterizing a duration of the time interval; the sigma is a coefficient determined according to the strength of voltage spike interference generated by the driving circuit, and 0< sigma < 1.
For example, the value of the coefficient σ is determined to be 0.9 according to the strength of the voltage spike interference generated by the driving circuit, and the level inversion period t corresponding to the previous level signal is obtained in step 402n-1＝3.32×10-4s, duration of time interval Tk＝2×10-6s, calculating the reference number T corresponding to the current level signal by the formulan＝149.4。
Step 404: it is determined whether the counter is greater than a reference number corresponding to the current level signal.
Specifically, after the reference number corresponding to the current level signal is calculated by the above formula, the counter Tc is compared with the reference number corresponding to the current level signal every time an interval elapses.
If the counter Tc is less than the reference number TnIt is noted that the difference between the duration of the current level signal and the level inversion period corresponding to the previous level signal is large, the actual position change signal does not appear, and the prediction of the actual position change signal is not made. In this case, even if the level signal acquired at the next time interval is inverted, the inverted level signal is not regarded as the true position change signal.
If the counter Tc is greater than the reference number TnIndicates that the current level signal has lastedThe real position change signal is about to occur close to the level inversion period corresponding to the previous level signal. At this time, the level signal which is inverted next time is determined as the real position change signal.
In the running process of the sensorless direct current brushless motor, if the rotating speed is uniform, the duration time of two adjacent level signals is equal, even if the rotating speed is not uniform, the duration time of each level signal is short, and the difference of the duration time of the two adjacent level signals is small, so that the current level signal overturn time can be predicted according to the duration time of the last level signal, in addition, the coefficient determined according to the intensity of voltage spike interference generated by a driving circuit is combined, the level signal overturn time can be accurately predicted, the real position change signal reflecting the rotor position can be accurately determined, and the sensorless direct current brushless motor can be accurately controlled according to the determined real position change signal.
Optionally, on the basis of the method for determining the relationship between the counter and the reference number shown in fig. 4, after the actual position change signal is acquired and the switching signal of the driving circuit is inverted, the counter is cleared to restart counting the number of time intervals that the next level signal passes after the current level signal is inverted.
After the actual position change signal is acquired for the current level signal, the switching signal of the driving circuit is inverted, and accordingly the level signal determined according to the reacquired first voltage value and the second voltage value is also changed, for example, the level signal determined before is high-low, the level signal determined after the switching signal of the driving circuit is inverted should be high-low-high, at this time, the number of time intervals that the high-low-high level signal passes needs to be counted to predict the next actual position change signal, so that the counter needs to be cleared after the switching signal of the driving circuit is inverted.
After the switching signal of the driving circuit is turned over every time, the counter is cleared to count the number of time intervals of the next level signal again, so that the actual position change signal of the next level signal is accurately predicted, the actual position change signal of the sensorless direct-current brushless motor can be continuously identified, and the sensorless direct-current brushless motor can be continuously and accurately controlled.
Optionally, on the basis of the sensorless dc brushless motor control method shown in fig. 1, step 106 is to invert the switching signal of the driving circuit, specifically, a next level signal corresponding to the current level signal may be determined according to an inversion rule of the level signal during the operation of the sensorless dc brushless motor, and then the switching signal of the driving circuit may be inverted according to the determined next level signal, which means that the ac power input by the driving circuit to the sensorless dc brushless motor matches the rotor position of the sensorless dc brushless motor.
For example, the level signal is cyclically inverted in the sequence of high-low, high-low, high-low-high, low-high-low, low-high during the operation of the sensorless dc brushless motor, and if the current level signal is high-low, after acquiring the true position change signal for the current level signal, the switching signal of the driving circuit needs to be inverted according to the level signal high-low-high. For example, as shown in fig. 2, when the level signal is high-low, the control chip in the driving circuit sends a switching signal 1 to the gates of 6 MOS transistors according to a control mode corresponding to the level signal high-low (the switching signal 1 includes a switch sub-signal corresponding to each MOS transistor respectively), and when the level signal is inverted to be high-low-high, the control chip in the driving circuit sends a switching signal 2 to the gates of 6 MOS transistors according to a control mode corresponding to the level signal high-low-high (the switching signal 2 also includes a switch sub-signal corresponding to each MOS transistor respectively).
The switching signal of the driving circuit is turned over according to the turning rule of the level signal in the operation process of the sensorless direct current brushless motor, the electric energy transmitted to the sensorless direct current brushless motor by the driving circuit is guaranteed to be matched with the rotor position of the sensorless direct current brushless motor, and the accuracy of controlling the sensorless direct current brushless motor is further guaranteed.
As shown in fig. 5 and 6, an embodiment of the present invention provides a sensorless dc brushless motor control apparatus. The device embodiments may be implemented by software, or by hardware, or by a combination of hardware and software. From a hardware aspect, as shown in fig. 5, a hardware structure diagram of a device in which the sensorless dc brushless motor control apparatus according to the embodiment of the present invention is located is shown, where in addition to the processor, the memory, the network interface, and the nonvolatile memory shown in fig. 5, the device in the embodiment may also include other hardware, such as a forwarding chip responsible for processing a message. Taking a software implementation as an example, as shown in fig. 6, as a logical apparatus, the apparatus is formed by reading, by a CPU of a device in which the apparatus is located, corresponding computer program instructions in a non-volatile memory into a memory for execution. The sensorless dc brushless motor control apparatus provided in this embodiment includes: the device comprises a collecting unit 601, a processing unit 602, a judging unit 603, a predicting unit 604 and a control unit 605;
the acquisition unit 601 is used for acquiring a first voltage value output by three phases of a driving circuit connected with the sensorless direct current brushless motor in a star connection mode and acquiring a second voltage value of a middle point of the star connection every time a preset time interval passes;
the processing unit 602 is configured to determine a current level signal corresponding to a current time interval according to the first voltage value and the second voltage value acquired by the acquisition unit 601;
a determining unit 603, configured to determine whether the number of time intervals corresponding to the current level signal determined by the processing unit 602 is greater than a reference number, where the reference number is determined according to a level flipping period corresponding to a previous level signal before the sensorless dc brushless motor flips to the current level signal;
a prediction unit 604, configured to determine, according to the determination result of the determination unit 603, that the next level signal that is turned over is a true position change signal if the number of time intervals corresponding to the current level signal is greater than the reference number;
a control unit 605 for inverting the switching signal of the drive circuit after the prediction unit 604 determines that the level signal at which the inversion occurs next time is the real position change signal and obtains the real position change signal.
Alternatively, on the basis of the sensorless dc brushless motor control apparatus shown in fig. 6, as shown in fig. 7, the processing unit 602 includes: a first comparator 6021, a second comparator 6022, a third comparator 6023, and an integration sub-unit 6024;
a first comparator 6021 configured to compare the U-phase voltage value included in the first voltage value with the second voltage value to obtain a U-phase level;
a second comparator 6022 for comparing the V-phase voltage value included in the first voltage value with the second voltage value to obtain a V-phase level;
a third comparator 6023 for comparing the W-phase voltage value included in the first voltage value with the second voltage value to obtain a W-phase level;
an integration sub-unit 6024 for determining the U-phase level obtained by the first comparator 6021, the V-phase level obtained by the second comparator 6022, and the W-phase level obtained by the third comparator 6023 as the current level signal.
Alternatively, on the basis of the sensorless dc brushless motor control apparatus shown in fig. 6, the determining unit 603 is configured to perform the following operations:
s1: after the current level signal is determined, adding 1 to the counter;
s2: acquiring a level overturning period corresponding to a previous level signal before the current level signal is overturned;
s3: calculating the reference quantity corresponding to the current level signal according to the level overturning period corresponding to the previous level signal by the following formula;
wherein, TnCharacterizing a reference quantity corresponding to a current level signal; t is tn-1Representing a level overturning period corresponding to the previous level signal; t iskCharacterizing a duration of the time interval; sigma represents a coefficient determined according to the strength of voltage spike interference generated by the driving circuit, and 0< sigma < 1;
s4: it is determined whether the counter is greater than a reference number corresponding to the current level signal.
Alternatively, on the basis of the sensorless dc brushless motor control apparatus provided in the above-described embodiment,
the judging unit 603 is further configured to clear the counter after the switching signal of the driving circuit is inverted, so as to restart counting the number of time intervals that the next level signal passes after the current level signal is inverted.
Alternatively, on the basis of the sensorless dc brushless motor control apparatus provided in the above embodiments,
the control unit 605 is configured to determine a next level signal corresponding to the current level signal according to an inversion rule of the level signal during the operation of the sensorless dc brushless motor, and invert a switching signal of the driving circuit according to the next level signal, so that the ac power input by the driving circuit to the sensorless dc brushless motor matches the rotor position of the sensorless dc brushless motor.
It should be noted that, because the contents of information interaction, execution process, and the like between the units in the apparatus are based on the same concept as the method embodiment of the present invention, specific contents may refer to the description in the method embodiment of the present invention, and are not described herein again.
The embodiment of the present invention further provides a readable medium, which includes an execution instruction, and when a processor of a storage controller executes the execution instruction, the storage controller executes the sensorless dc brushless motor control method provided in each of the above embodiments.
An embodiment of the present invention further provides a storage controller, including: a processor, a memory, and a bus;
the memory is used for storing execution instructions, the processor is connected with the memory through the bus, and when the memory controller runs, the processor executes the execution instructions stored in the memory, so that the memory controller executes the sensorless direct current brushless motor control method provided by the above embodiments.
It should be noted that the sensorless dc brushless motor control apparatus provided in each embodiment of the present invention may be implemented by a processing chip storing a corresponding computer program, or may be implemented by a corresponding logic circuit.
In summary, the sensorless dc brushless motor control method and apparatus provided in the embodiments of the present invention at least have the following advantages:
1. in the embodiment of the invention, the sensorless DC brushless motor is connected with the three-phase output of the drive circuit in a star connection mode, then a first voltage value of the three-phase output of the drive circuit and a second voltage value of the midpoint of the star connection are collected once every preset time interval, then a current level signal corresponding to the current time interval can be obtained according to the collected first voltage value and second voltage value, then whether the number of the passed time intervals corresponding to the current level signal is larger than a reference number is judged, the reference number is determined according to the level inversion period of the last level signal after the sensorless DC brushless motor is inverted into the current level signal, if the judgment result is that the number of the passed time intervals corresponding to the current level signal is larger than the reference number, the level signal which is inverted next time is determined to be a real position change signal, and then, the level signal which is firstly obtained and is overturned is used as a real position change signal, and a switching signal of the driving circuit is overturned after the real position change signal is obtained. Therefore, the turning time of the current level signal is predicted according to the duration time of the last level signal aiming at each level signal reflecting the position of the rotor in the running process of the sensorless direct current brushless motor, so that the voltage spike interference generated by a power device in the level signal is filtered out, and the real position change signal is not detected to generate time delay due to the fact that a filter circuit is not used, so that the accuracy of controlling the sensorless direct current brushless motor can be improved.
2. In the embodiment of the invention, the control chip in the driving circuit is respectively connected with the grid of each MOS tube, and after the real position change signal reflecting the real position of the rotor in the sensorless DC brushless motor is obtained, the control chip in the driving circuit can be sent with a corresponding instruction, so that the control chip can change the switch signal output to the grid of each MOS tube, and further the driving circuit inputs the voltage corresponding to the real position of the rotor to the sensorless DC brushless motor, thereby realizing the accurate control of the operation of the sensorless DC brushless motor.
3. In the embodiment of the invention, during the operation of the sensorless DC brushless motor, if the rotating speed is uniform, the time duration of two adjacent level signals is equal, even if the rotation speed is not uniform, since the duration of each level signal is short, the difference between the durations of adjacent two level signals is small, the time when the current level signal is inverted can be predicted according to the time when the last level signal lasts, in addition, the coefficient determined according to the intensity of the voltage spike interference generated by the driving circuit is combined to ensure that the time for the level signal to turn over can be more accurately predicted, the real position change signal reflecting the position of the rotor can be more accurately determined, and then the sensorless direct current brushless motor can be more accurately controlled according to the determined real position change signal.
4. In the embodiment of the invention, after the switching signal of the driving circuit is turned over each time, the counter is cleared to count the number of time intervals of the next level signal again, so as to accurately predict the real position change signal of the next level signal, and thus, the real position change signal of the sensorless direct current brushless motor can be continuously identified, and the sensorless direct current brushless motor can be continuously and accurately controlled.
5. In the embodiment of the invention, the switching signal of the driving circuit is overturned according to the overturning rule of the level signal in the operation process of the sensorless direct current brushless motor, so that the electric energy transmitted to the sensorless direct current brushless motor by the driving circuit is ensured to be matched with the rotor position of the sensorless direct current brushless motor, and the accuracy of controlling the sensorless direct current brushless motor is further ensured.
It is noted that, herein, relational terms such as first and second, and the like may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Also, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising a" does not exclude the presence of other similar elements in a process, method, article, or apparatus that comprises the element.
Those of ordinary skill in the art will understand that: all or part of the steps for realizing the method embodiments can be completed by hardware related to program instructions, the program can be stored in a computer readable storage medium, and the program executes the steps comprising the method embodiments when executed; and the aforementioned storage medium includes: various media that can store program codes, such as ROM, RAM, magnetic or optical disks.
Finally, it is to be noted that: the above description is only a preferred embodiment of the present invention, and is only used to illustrate the technical solutions of the present invention, and not to limit the protection scope of the present invention. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention shall fall within the protection scope of the present invention.
Claims (8)
1. A sensorless DC brushless motor control method is characterized in that a sensorless DC brushless motor is connected with a three-phase output of a driving circuit in a star connection mode, and the method further comprises the following steps:
collecting a first voltage value output by three phases of the driving circuit and collecting a second voltage value of the middle point of the star connection every time a preset time interval passes;
determining a current level signal corresponding to a current time interval according to the first voltage value and the second voltage value;
judging whether the number of the time intervals corresponding to the current level signal is larger than a reference number, wherein the reference number is determined according to a level overturning period corresponding to a previous level signal before the sensorless brushless direct current motor is overturned to the current level signal;
if the number of the time intervals corresponding to the current level signal is larger than the reference number, determining that the level signal which is overturned next time is a real position change signal;
after the real position change signal is obtained, turning over a switching signal of the driving circuit;
the determining whether the number of the time intervals corresponding to the current level signal is greater than a reference number includes:
s1: after the current level signal is determined, adding 1 to a counter;
s2: acquiring a level overturning period corresponding to a previous level signal before the current level signal is overturned;
s3: calculating the reference number corresponding to the current level signal according to a level flip period corresponding to the previous level signal by the following formula;
wherein, T isnCharacterizing the reference quantity corresponding to the current level signal; said t isn-1Representing a level turnover period corresponding to the previous level signal; the T iskCharacterizing a duration of the time interval; the sigma characterization is according to the driving circuitGenerating a coefficient determined by the strength of the voltage spike interference, wherein 0 & lt sigma & lt 1;
s4: determining whether the counter is greater than the reference number corresponding to the current level signal.
2. The method of claim 1, wherein the driving circuit comprises: the MOS transistor comprises a control chip, a first MOS transistor, a second MOS transistor, a third MOS transistor, a fourth MOS transistor, a fifth MOS transistor and a sixth MOS transistor;
the drain electrodes of the first MOS tube, the third MOS tube and the fifth MOS tube are all connected with an external direct-current power supply;
the source electrodes of the second MOS tube, the fourth MOS tube and the sixth MOS tube are all grounded;
the source electrode of the first MOS tube is connected with the drain electrode of the second MOS tube, the source electrode of the third MOS tube is connected with the drain electrode of the fourth MOS tube, and the source electrode of the fifth MOS tube is connected with the drain electrode of the sixth MOS tube;
the source electrode of the first MOS tube is connected with a U-phase winding voltage input end of the sensorless direct-current brushless motor, the source electrode of the third MOS tube is connected with a V-phase voltage input end of the sensorless direct-current brushless motor, and the source electrode of the fifth MOS tube is connected with a W-phase voltage input end of the sensorless direct-current brushless motor;
the gates of the first MOS tube and the second MOS tube are respectively connected with two U-phase control pins on the control chip, the gates of the third MOS tube and the fourth MOS tube are respectively connected with two V-phase control pins on the control chip, and the gates of the fifth MOS tube and the sixth MOS tube are respectively connected with two W-phase control pins on the control chip;
the control chip is used for sending switching signals to the first MOS tube, the second MOS tube, the third MOS tube, the fourth MOS tube, the fifth MOS tube and the sixth MOS tube.
3. The method of claim 1, wherein determining a current level signal corresponding to a current time interval based on the first voltage value and the second voltage value comprises:
comparing the U-phase voltage value included in the first voltage value with the second voltage value to obtain a U-phase level;
comparing the voltage value of the V-phase included by the first voltage value with the second voltage value to obtain a V-phase level;
comparing the W-phase voltage value included in the first voltage value with the second voltage value to obtain a W-phase level;
determining the obtained U-phase level, V-phase level and W-phase level as the current level signal.
4. The method of claim 1, further comprising, after said toggling the switching signal of the driving circuit:
and clearing the counter to restart counting the number of the time intervals of the next level signal after the current level signal is overturned.
5. The method according to any one of claims 1 to 4, wherein the inverting the switching signal of the driving circuit comprises:
determining a next level signal relative to the current level signal according to the turning rule of the level signal in the operation process of the sensorless direct current brushless motor;
and turning over a switching signal of the driving circuit according to the next level signal, so that the alternating current input by the driving circuit into the sensorless direct current brushless motor is matched with the rotor position of the sensorless direct current brushless motor.
6. A sensorless dc brushless motor control apparatus, comprising: the device comprises an acquisition unit, a processing unit, a judgment unit, a prediction unit and a control unit;
the acquisition unit is used for acquiring a first voltage value output by three phases of a driving circuit connected with the sensorless direct current brushless motor in a star connection mode every time a preset time interval passes, and acquiring a second voltage value of a middle point of the star connection;
the processing unit is used for determining a current level signal corresponding to a current time interval according to the first voltage value and the second voltage value acquired by the acquisition unit;
the judging unit is configured to judge whether the number of the time intervals corresponding to the current level signal determined by the processing unit is greater than a reference number, where the reference number is determined according to a level flipping period corresponding to a previous level signal before the sensorless dc brushless motor flips to the current level signal;
the prediction unit is used for determining that the next level signal which is overturned is a real position change signal if the number of the time intervals corresponding to the current level signal is larger than the reference number according to the judgment result of the judgment unit;
the control unit is used for inverting the switching signal of the driving circuit after the prediction unit determines that the level signal which is inverted next time is a real position change signal and obtains the real position change signal;
the judging unit is used for executing the following operations:
s1: after the current level signal is determined, adding 1 to a counter;
s2: acquiring a level overturning period corresponding to a previous level signal before the current level signal is overturned;
s3: calculating the reference number corresponding to the current level signal according to a level flip period corresponding to the previous level signal by the following formula;
T_n＝(σ·t_(n-1))/T_k
wherein the T _ n characterizes the reference number corresponding to the current level signal; the t _ (n-1) represents a level overturning period corresponding to the previous level signal; the T _ k represents the duration of the time interval; the sigma represents a coefficient determined according to the strength of voltage spike interference generated by the driving circuit, and 0< sigma < 1;
s4: determining whether the counter is greater than the reference number corresponding to the current level signal.
7. The apparatus of claim 6, wherein the processing unit comprises: the integrated circuit comprises a first comparator, a second comparator, a third comparator and an integrated subunit;
the first comparator is used for comparing the U-phase voltage value included in the first voltage value with the second voltage value to obtain a U-phase level;
the second comparator is used for comparing the voltage value of the V-phase included by the first voltage value with the second voltage value to obtain a V-phase level;
the third comparator is used for comparing the W-phase voltage value included in the first voltage value with the second voltage value to obtain a W-phase level;
the integration subunit is configured to determine the U-phase level obtained by the first comparator, the V-phase level obtained by the second comparator, and the W-phase level obtained by the third comparator as the current level signal.
8. The apparatus of claim 6,
the judging unit is further configured to clear the counter after the switching signal of the driving circuit is inverted, so as to restart counting of the number of the time intervals that a next level signal passes after the current level signal is inverted.
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