CN108631660B

CN108631660B - Rotor positioning method, positioning device and control system of brushless direct current motor

Info

Publication number: CN108631660B
Application number: CN201810295451.0A
Authority: CN
Inventors: 王浩东; 万德康; 吴偏偏
Original assignee: Midea Group Co Ltd; Jiangsu Midea Cleaning Appliances Co Ltd
Current assignee: Midea Group Co Ltd; Jiangsu Midea Cleaning Appliances Co Ltd
Priority date: 2018-03-30
Filing date: 2018-03-30
Publication date: 2020-04-10
Anticipated expiration: 2038-03-30
Also published as: CN110868116A; CN110868116B; CN108631660A

Abstract

The invention discloses a rotor positioning method, a positioning device and a control system of a brushless direct current motor, wherein the positioning method comprises the following steps: when conducting control is carried out on the stator winding of the motor according to a preset conducting mode, voltage detection pulses are sequentially applied to different phases of the stator winding of the motor, and a plurality of times are obtained by obtaining the time required by the current value of the stator winding at each phase to reach a preset current value; acquiring a preset time-sector relation table according to a preset conduction mode; and acquiring the sector where the rotor of the motor is located according to the plurality of times and a preset time-sector relation table, and acquiring the rotor position of the motor according to the sector where the rotor of the motor is located. Therefore, the rotor position of the motor can be quickly and accurately obtained, the problems of abnormal sound, shaking and positioning errors can be avoided, the method is simple, and blind-area-free positioning can be realized.

Description

Rotor positioning method, positioning device and control system of brushless direct current motor

Technical Field

The present invention relates to the field of motor control technologies, and in particular, to a rotor positioning method for a brushless dc motor, a rotor positioning device for a brushless dc motor, and a control system for a brushless dc motor.

Background

At present, in the field of sensorless drive control technology of brushless dc motors, there are two main rotor positioning technologies under the conditions of motor standstill and near zero speed: forced pre-positioning and pulse positioning.

The forced pre-positioning method does not consider the current position of the motor rotor, but energizes the fixed phase of the motor stator winding to rotate the motor rotor to a preset position. However, this approach has the following disadvantages: 1) the positioning time is long, and the method is not suitable for occasions requiring quick starting of the motor; 2) in order to reduce the positioning time or increase the positioning reliability, the PWM duty ratio during positioning needs to be increased, which increases the starting current and increases the power consumption, and in some occasions powered by a battery, the system efficiency is reduced; 3) reverse rotation may occur during positioning, and the method is not suitable for occasions requiring no reverse rotation when the motor is started; 4) jitter and abnormal sound easily occur during positioning.

The pulse positioning method is to apply short-time current pulses to different phases of the stator winding of the motor and to judge the position of the rotor according to the magnitude or duration of the current pulses. However, this approach has the following disadvantages: 1) the rotor positions which can not cover the full 360 degrees are positioned by the pulses of 120 degrees, and a blind area exists, so that the N-S pole reversal error is caused; 2) the judgment process is complex, the software code amount is increased, and the judgment time is prolonged.

Disclosure of Invention

The present invention is directed to solving, at least to some extent, one of the technical problems in the related art. Therefore, a first objective of the present invention is to provide a rotor positioning method for a brushless dc motor, which can greatly reduce the time for starting and positioning the motor, ensure that the motor does not reverse when started, solve abnormal noise and jitter during positioning, solve the problem of positioning error caused by mismatching of current waveform and rotor position during pulse positioning, simplify the identification method for the rotor position during pulse positioning, and simultaneously achieve full 360 ° non-blind area positioning.

A second object of the invention is to propose a non-transitory computer-readable storage medium.

The third object of the present invention is to provide a rotor positioning device of a brushless dc motor.

A fourth object of the present invention is to provide a control system for a brushless dc motor.

In order to achieve the above object, a first embodiment of the present invention provides a method for positioning a rotor of a brushless dc motor, including: when conducting control is carried out on a stator winding of a motor according to a preset conducting mode, voltage detection pulses are sequentially applied to different phases of the stator winding of the motor, and a plurality of times are obtained by obtaining the time required by the current value of the stator winding at each phase to reach a preset current value; acquiring a preset time-sector relation table according to the preset conduction mode; and acquiring the sector where the rotor of the motor is located according to the plurality of times and the preset time-sector relation table, and acquiring the rotor position of the motor according to the sector where the rotor of the motor is located.

According to the rotor positioning method of the brushless direct current motor, when conducting control is carried out on the stator winding of the motor according to the preset conducting mode, voltage detection pulses are sequentially applied to different phases of the stator winding of the motor, time required by the current value of the stator winding in each phase to reach the preset current value is obtained to obtain a plurality of times, the preset time-sector relation table is obtained according to the preset conducting mode, the sector where the rotor of the motor is located is obtained according to the plurality of times and the preset time-sector relation table, and the rotor position of the motor is obtained according to the sector where the rotor of the motor is located. Therefore, the time for starting and positioning the motor can be greatly shortened, the motor can not be reversely rotated when being started, abnormal sound and shaking during positioning are solved, the problem of positioning error caused by mismatching of current waveforms and rotor positions during pulse positioning can be solved, the pulse positioning rotor position identification method is simplified, and meanwhile, full 360-degree non-blind-area positioning can be realized.

In addition, the rotor positioning method of the brushless dc motor according to the above embodiment of the present invention may further have the following additional technical features:

according to an embodiment of the present invention, when the preset conduction mode is a two-phase conduction mode, the preset time-sector relationship table is as follows:

relative magnitude of time relationship	Sector number
		(T_BA<T _ CB) and (T _ CB)<T _ AC) and (T _ BC)<T _ AB) and (T _ AB)<T_CA)	I
(T_AC<T _ CB) and (T _ CB)<T _ BA) and (T _ BC)<T_CA) And (T _ CA)<T_AB)	III
		(T_AC<T _ BA) and (T _ BA)<T _ CB) and (T _ AB)<T _ CA) and (T _ CA)<T_BC)	II
(T_CB<T _ BA) and (T _ BA)<T _ AC) and (T _ AB)<T _ BC) and (T _ BC)<T_CA)	VI
		(T_CB<T _ AC) and (T _ AC)<T _ BA) and (T _ CA)<T _ BC) and (T _ BC)<T_AB)	IV
(T_BA<T _ AC) and (T _ AC)<T _ CB) and (T _ CA)<T _ AB) and (T _ AB)<T_BC)	V

The time required for the current values of the stator windings in the AB phase, the BC phase, the CA phase, the BA phase, the CB phase and the AC phase to reach the preset current value is respectively T _ AB, T _ BC, T _ CA, T _ BA, T _ CB and T _ AC.

According to another embodiment of the present invention, when the preset conduction mode is a three-phase conduction mode, the preset time-sector relationship table is as follows:

and the time required for the current values of the stator windings in the A + phase, the B + phase, the C + phase, the A-phase, the B-phase and the C-phase to reach the preset current value is respectively T _ A +, T _ B +, T _ C +, T _ A-, T _ B-and T _ C-.

According to an embodiment of the present invention, when the plurality of times do not satisfy the preset time-sector relation table, the shortest time among the plurality of times is further obtained, the direction to be rotated of the motor is obtained, and the sector where the rotor of the motor is located is obtained according to the shortest time and the direction to be rotated.

According to one embodiment of the present invention, after the time required for the current value of the stator winding at any phase to reach the preset current value is obtained, a reverse voltage detection pulse is further applied at any phase for a first preset time to cancel the energy accumulated on the stator winding by the voltage detection pulse.

In order to achieve the above object, a non-transitory computer readable storage medium is provided according to a second aspect of the present invention, and a computer program is stored thereon, and when executed by a processor, the non-transitory computer readable storage medium implements the above method for positioning a rotor of a brushless dc motor.

According to the non-transitory computer readable storage medium of the embodiment of the invention, by executing the rotor positioning method of the brushless direct current motor, the time for starting and positioning the motor can be greatly shortened, the motor is ensured not to be reversed when being started, abnormal sound and jitter during positioning are solved, the problem of positioning error caused by mismatching of a current waveform during pulse positioning and the position of the rotor can be solved, the pulse positioning rotor position identification method is simplified, and meanwhile, full 360-degree blind-area-free positioning can be realized.

In order to achieve the above object, a rotor positioning device for a brushless dc motor according to an embodiment of a third aspect of the present invention includes: a given unit for applying voltage detection pulses at different phases of a stator winding of the motor; the current obtaining unit is used for obtaining the current value of the stator winding at each phase; the time acquisition unit is used for acquiring the time required by the current value of the stator winding at each phase to reach a preset current value; the control unit is used for sequentially applying voltage detection pulses to different phases of the stator winding of the motor through the given unit when conducting control is conducted on the stator winding of the motor according to a preset conducting mode, acquiring time required by a current value of the stator winding at each phase to reach a preset current value through the time acquisition unit to obtain a plurality of times, acquiring a preset time-sector relation table according to the preset conducting mode, acquiring a sector where a rotor of the motor is located according to the plurality of times and the preset time-sector relation table, and acquiring the position of the rotor of the motor according to the sector where the rotor of the motor is located.

According to the rotor positioning device of the brushless direct current motor, when the control unit conducts control on the stator winding of the motor according to the preset conducting mode, the given unit sequentially applies voltage detection pulses to different phases of the stator winding of the motor, the time acquisition unit acquires the time required by the current value of the stator winding in each phase to reach the preset current value so as to acquire a plurality of times, the preset time-sector relation table is acquired according to the preset conducting mode, the sector where the rotor of the motor is located is acquired according to the plurality of times and the preset time-sector relation table, and the rotor position of the motor is acquired according to the sector where the rotor of the motor is located. Therefore, the time for starting and positioning the motor can be greatly shortened, the motor can not be reversely rotated when being started, abnormal sound and shaking during positioning are solved, the problem of positioning error caused by mismatching of current waveforms and rotor positions during pulse positioning can be solved, the pulse positioning rotor position identification method is simplified, and meanwhile, full 360-degree non-blind-area positioning can be realized.

In addition, the rotor positioning device of the brushless dc motor according to the above embodiment of the present invention may further have the following additional technical features:

relative magnitude of time relationship	Sector number
		(T_BA<T _ CB) and (T _ CB)<T _ AC) and (T _ BC)<T _ AB) and (T _ AB)<T_CA)	I
(T_AC<T _ CB) and (T _ CB)<T _ BA) and (T _ BC)<T _ CA) and (T _ CA)<T_AB)	III
		(T_AC<T _ BA) and (T _ BA)<T _ CB) and (T _ AB)<T _ CA) and (T _ CA)<T_BC)	II
(T_CB<T _ BA) and (T _ BA)<T _ AC) and (T _ AB)<T _ BC) and (T _ BC)<T_CA)	VI
		(T_CB<T _ AC) and (T _ AC)<T _ BA) and (T _ CA)<T _ BC) and (T _ BC)<T_AB)	IV
(T_BA<T _ AC) and (T _ AC)<T _ CB) and (T _ CA)<T _ AB) and (T _ AB)<T_BC)	V

relative magnitude of time relationship	Sector number
		(T _ B + < T _ A +) and (T _ A + < T _ C +) and (T _ A- < T _ B-) and (T _ B- < T _ C-)	I
(T _ B + < T _ C +) and (T _ C + < T _ A +) and (T _ C- < T _ B-) and (T _ B- < T _ A-)	III
		(T _ A + < T _ C +) and (T _ C + < T _ B +) and (T _ C- < T _ A-) and (T _ A- < T _ B-)	II
(T _ A + < T _ B +) and (T _ B + < T _ C +) and (T _ B- < T _ A-) and (T _ A- < T _ C-)	VI
		(T _ C + < T _ B +) and (T _ B + < T _ A +) and (T _ B- < T _ C-) and (T _ C- < T _ A-)	IV
(T _ C + < T _ A +) and (T _ A + < T _ B +) and (T _ A- < T _ C-) and (T _ C- < T _ B-)	V

According to an embodiment of the present invention, when the plurality of times do not satisfy the preset time-sector relation table, the control unit further obtains a shortest time among the plurality of times, obtains a direction to be rotated of the motor, and obtains a sector in which a rotor of the motor is located according to the shortest time and the direction to be rotated.

According to an embodiment of the present invention, after the time required for the current value of the stator winding at any one phase to reach the preset current value is acquired by the time acquisition unit, the control unit further applies a reverse voltage detection pulse of a first preset time to the any one phase by the given unit to cancel the energy accumulated on the stator winding by the voltage detection pulse.

In order to achieve the above object, a fourth aspect of the present invention provides a control system for a brushless dc motor, which includes the above rotor positioning device for a brushless dc motor.

According to the control system of the brushless direct current motor, the rotor positioning device of the brushless direct current motor can greatly reduce the time for starting and positioning the motor, ensure that the motor cannot rotate reversely when being started, solve abnormal sound and jitter during positioning, solve the problem of positioning error caused by mismatching of current waveform and rotor position during pulse positioning, simplify the identification method of the pulse positioning rotor position, and simultaneously realize full 360-degree blind-area-free positioning.

Drawings

FIG. 1 is a composite magnetic potential vector diagram for a brushless DC motor;

fig. 2 is a flowchart of a rotor positioning method of a brushless dc motor according to an embodiment of the present invention;

FIG. 3 is a schematic diagram of a control system for a brushless DC motor according to one embodiment of the present invention;

FIG. 4 is a timing diagram of pulse injection in a two-phase conduction mode according to one embodiment of the present invention;

FIG. 5 is a diagram of a pulse current waveform in a two-phase conduction mode according to an embodiment of the present invention;

FIG. 6 is a schematic view of a sector of a brushless DC motor according to an embodiment of the present invention;

FIG. 7 is a flow chart of a method of positioning a rotor of a brushless DC motor according to one embodiment of the present invention;

fig. 8 is a block diagram illustrating a rotor positioning apparatus of a brushless dc motor according to an embodiment of the present invention.

Detailed Description

Reference will now be made in detail to embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like or similar reference numerals refer to the same or similar elements or elements having the same or similar function throughout. The embodiments described below with reference to the drawings are illustrative and intended to be illustrative of the invention and are not to be construed as limiting the invention.

A rotor positioning method of a brushless dc motor, a non-transitory computer-readable storage medium, a rotor positioning apparatus of a brushless dc motor, and a control system of a brushless dc motor according to embodiments of the present invention are described below with reference to the accompanying drawings.

Generally, a current-carrying coil is wound around a stator core of a brushless dc motor, and when a current is applied to the current-carrying coil, a certain magnetic flux is generated in the stator core. The winding inductance can change along with the saturation degree of a magnetic circuit, so that when the motor is static or rotates, if the direction of magnetic flux generated by a permanent magnet (rotor) is consistent with the direction of magnetic flux generated by winding current, a magnetizing effect is generated, the saturation degree of the magnetic circuit of a stator core is increased, and the winding inductance is reduced; on the contrary, the saturation degree of the magnetic circuit of the stator core is reduced, and the winding inductance is increased. Therefore, the relative position of the rotor and the stator is different and is directly reflected on the magnitude of the winding inductance.

As is well known, the motor voltage formula is:

U＝Ri+L*di/dt+e (1)

wherein, U is direct current bus voltage, R is stator winding internal resistance, i is armature current, L is stator winding inductance, and e is the back electromotive force of the motor.

When the motor is at rest, the back electromotive force e of the motor is zero, and since the internal resistance R of the stator winding is small in practice, the voltage drop across it is negligible with respect to the dc bus voltage U applied to the stator winding, the above equation (1) can be simplified as:

U＝L*di/dt≈L*Δi/Δt (2)

it can be seen from formula (2) that when U is constant, L is inversely proportional to the change of Δ i, i.e., the larger L, the smaller Δ i, and vice versa; Δ i is proportional to Δ t, and the larger Δ t, the larger Δ i.

The pulse positioning method (also called as a short-time pulse method) is to select 6 short-time voltage detection pulses with proper widths by utilizing the stator core saturation effect principle, apply voltage to a stator winding of a motor in sequence according to a corresponding electrifying sequence, sample a current value and compare the current value to determine an electrical angle interval where a rotor is located. Each electrical cycle of the motor corresponds to 360 electrical degrees, wherein each 60 electrical degrees is a conduction interval, referred to as a sector for short, and the total number of the sectors is 6. For ease of description and simplicity of analysis, a vector diagram of magnetic potential is drawn, as shown in FIG. 1.

In the related art, when a pulse positioning method is used for rotor positioning, the method is mainly realized by the following two ways: one is to apply current pulses in the directions of B + A-, C + B-and A + C- (or A + B-, B + C-and C + A-) and collect corresponding current magnitude, and determine the sector where the rotor is located by comparing the relative magnitude relation; and the other method is to apply current pulses in the directions of A + B-, B + A-, C + B-, B + C-, C + A-and A + C-respectively, collect corresponding current magnitude, and then sequentially judge the relative magnitude relations of iAB and iBA, iBC and iCB, and iAC and iCA to obtain the sector where the rotor is located.

However, the above two approaches have the following disadvantages: 1) the rotor positions which can not cover the full 360 degrees are positioned by the pulses of 120 degrees, and a blind area exists, so that the N-S pole reversal error is caused; 2) the judgment process is complex, the software code amount is increased, and the judgment time is prolonged. Therefore, the invention provides a rotor positioning method of a brushless direct current motor, which can solve the problems of long positioning time, possible reversal in positioning and easy jitter and abnormal sound in positioning caused by adopting a forced positioning method, and can solve the problems of N-S pole reversal error, more complex judgment method and software code amount and judgment time increase caused by the fact that a pulse positioning method cannot cover the rotor position of a full 360 degrees, a blind zone exists, and the like.

Fig. 2 is a flowchart of a rotor positioning method of a brushless dc motor according to an embodiment of the present invention. As shown in fig. 2, the method for positioning a rotor of a brushless dc motor according to an embodiment of the present invention includes the following steps:

and S1, when conducting control is carried out on the stator winding of the motor according to the preset conducting mode, voltage detection pulses are sequentially applied to different phases of the stator winding of the motor, and a plurality of times are obtained by acquiring the time required by the current value of the stator winding at each phase to reach the preset current value.

In some embodiments of the present invention, the predetermined conduction mode is a two-phase conduction mode or a three-phase conduction mode. Wherein, according to the schematic diagram of the hardware principle shown in fig. 3, the vectors in the two-phase conduction mode are listed as follows:

q1, Q4 are turned on → a + B- (denoted as AB), that is, when the switching tubes Q1 and Q4 are turned on, the current flows: the positive end P + of the direct-current bus voltage → the switching tube Q1 → the A-phase stator winding → the B-phase stator winding → the switching tube Q4 → the negative end P-of the direct-current bus voltage, which corresponds to the vector A + B-, is marked as the conduction of the AB phase of the stator winding;

q1, Q2 are conducted → A + C- (noted as AC);

q3, Q2 turn on → B + C- (denoted as BC);

q3, Q6 are conducted → B + A- (noted as BA);

q5, Q6 turn on → C + A- (denoted as CA);

q5, Q4 turn on → C + B- (noted as CB).

The vector under the three-phase conduction mode is:

q1, Q4, Q2 are turned on → a + B-C- (denoted as a +), that is, when the switching tubes Q1, Q4 and Q2 are turned on, the current flows: the positive end P + of the direct-current bus voltage → the switching tube Q1 → the A-phase stator winding → the B-phase stator winding and the C-phase stator winding → the switching tube Q4 and the switching tube Q2 → the negative end P-of the direct-current bus voltage, and a corresponding vector A + B-C-, which is recorded as the conduction of the A + phase of the stator winding;

q3, Q6, Q2 are conducted → B + A-C- (marked as B +);

q4, Q6, Q4 are conducted → C + A-B- (as C +);

q6, Q3, Q5 are turned on → A-B + C + (denoted as A-);

q4, Q1, Q5 are turned on → B-A + C + (noted as B-);

q2, Q1, Q3 are turned on → C-A + B + (denoted as C-).

When the rotor of the motor is positioned, a group of vectors in a two-phase conduction mode or a three-phase conduction mode can be selected as a positioning pulse vector, and the two-phase conduction mode is taken as an example.

Firstly, according to the formula (2), the magnitude of current that can be borne by power devices (switching tubes Q1-Q6) in an actual three-phase inverter bridge and the load capacity (instantaneous current output capacity) of a power supply, a proper current threshold is selected as a preset current value, which is denoted as i2, and in the embodiment of the invention, i2 may be 10A.

As shown in fig. 3, the Microcontroller (MCU) may first control the switching tubes Q1 and Q4 to be turned on to turn on the AB phase of the stator winding, and simultaneously record an initial value T1 of the timer1, and start the timer1 until the current value of the stator winding obtained by the current sampling module reaches a preset current value i2, record a count value T1 'of the timer1 at that time, subtract T1 from T1' to obtain a time (i.e., Δ T in the above principle) required for the current value to reach the preset current value when the AB phase of the stator winding is turned on, and simultaneously control the switching tubes Q1 and Q4 to be turned off to turn off the AB phase of the stator winding.

Then, the microcontroller controls the switch tubes Q3 and Q2 to be turned on to turn on the BC phase of the stator winding, records an initial value T2 of the timer2, starts the timer2 until the current value of the stator winding obtained by the current sampling module reaches a preset current value i2, records a count value T2 'of the timer2 at the moment, subtracts T2 from T2' to obtain a time T _ BC required by the current value of the stator winding to reach the preset current value when the BC phase is turned on, and controls the switch tubes Q3 and Q2 to be turned off to turn off the BC phase of the stator winding.

According to the mode, the time T _ CA required for the current value to reach the preset current value when the CA phase of the stator winding is conducted, the time T _ BA required for the current value to reach the preset current value when the BA phase of the stator winding is conducted, the time T _ CB required for the current value to reach the preset current value when the CB phase of the stator winding is conducted, the time T _ AC required for the current value to reach the preset current value when the AC phase of the stator winding is conducted are obtained, and finally six times are obtained, namely T _ AB, T _ BC, T _ CA, T _ BA, T _ CB and T _ AC.

It should be noted that the pulse injection process in the above example is in the order of AB, BC, CA, BA, CB, and AC, but this order is not essential, and may be ordered arbitrarily, and has no influence on the result of determining the sector where the rotor is located. In addition, the three-phase conduction mode is similar to the two-phase conduction mode, and the details are not described here.

In some embodiments of the present invention, after the time required for the current value of the stator winding at any phase to reach the preset current value is obtained, the reverse voltage detection pulse is also applied at any phase for a first preset time to cancel the energy accumulated on the stator winding by the voltage detection pulse.

Specifically, a two-phase conduction manner is still taken as an example. As shown in fig. 3 and 4, the microcontroller may first control the switching tubes Q1 and Q4 to be turned on to turn on the AB phase of the stator winding, and simultaneously record an initial value T1 of the timer1, and start the timer1 until the current value of the stator winding obtained by the current sampling module reaches a preset current value i2, record a count value T1 'of the timer1 at this time, and subtract T1 from T1' to obtain a time T _ AB required for the current value to reach the preset current value when the AB phase of the stator winding is turned on, and simultaneously control the switching tubes Q1 and Q4 to be turned off to turn off the AB phase of the stator winding.

Then, the microcontroller controls the switching tubes Q3 and Q6 to be turned on, so that the BA phase of the stator winding is turned on, and the first preset time T _ BA' is maintained, which is used for counteracting the energy accumulated on the stator winding when the previous AB phase is turned on to influence the subsequent current collection. The value taking method of the first preset time T _ BA' is as follows: firstly, T _ BA ' ═ T _ AB, then, through observation of an oscilloscope, the value of the first preset time T _ BA ' is adjusted in software, and when the pulse current in the stator winding monotonically decreases to the minimum, the value of the first preset time T _ BA ' is determined, as shown in fig. 5.

Then, the microcontroller controls the switch tubes Q3 and Q2 to be turned on to turn on the BC phase of the stator winding, records an initial value T2 of the timer2, starts the timer2 until the current value of the stator winding obtained by the current sampling module reaches a preset current value i2, records a count value T2 'of the timer2 at the moment, subtracts T2 from T2' to obtain a time T _ BC required by the current value of the stator winding to reach the preset current value when the BC phase is turned on, and controls the switch tubes Q3 and Q2 to be turned off to turn off the BC phase of the stator winding. Then, the microcontroller controls the switching tubes Q5 and Q4 to be turned on to turn on the CB phase of the stator winding, and maintains the first preset time T _ CB 'for counteracting the energy accumulated on the stator winding when the previous BC phase is turned on to influence the subsequent current collection, and controls the switching tubes Q5 and Q4 to be turned off when the time reaches the first preset time T _ CB', so as to turn off the CB phase of the stator winding. It should be noted that, when performing current cancellation on each phase, the first preset time may be different.

According to the mode, the time T _ CA required for the current value to reach the preset current value when the CA phase of the stator winding is conducted is obtained in sequence, the time T _ BA required for the current value to reach the preset current value when the BA phase of the stator winding is conducted, the time T _ CB required for the current value to reach the preset current value when the CB phase of the stator winding is conducted, the time T _ AC required for the current value to reach the preset current value when the AC phase of the stator winding is conducted, and after the corresponding time when each phase is conducted is obtained, the current offset operation is carried out, namely, the phase conducting sequence of the stator winding is as follows: AB. And finally obtaining six times, namely T _ AB, T _ BC, T _ CA, T _ BA, T _ CB and T _ AC.

After the required time is obtained, current offset operation is carried out on the corresponding phase, so that the situation that the collected current value cannot reflect the real size and the positioning failure is caused due to the current judgment error is avoided effectively because the reverse pulse current caused by injecting the reverse pulse (such as BA) and obtaining the corresponding current value is not really established after the forward pulse is injected (such as AB) and obtaining the corresponding current value is effectively avoided, and the positioning of the rotor is more accurate and reliable.

In some embodiments of the present invention, when obtaining the time required for the current value of the stator winding in any phase to reach the preset current value, the method further includes: judging whether the current value is within a preset current range or not and judging whether the time is within a preset time range or not; and if the current value is not in the preset current range or the time is not in the preset time range, stopping acquiring the time required by the current value of any phase to reach the preset current value, and determining an invalid sector according to any phase so as to perform fault processing according to the invalid sector. The preset current range and the preset time range can be calibrated according to actual conditions.

Specifically, in both the two-phase conduction method and the three-phase conduction method, when the voltage detection pulse is applied to different phases of the stator winding, the time of the pulse current is very short (generally, us-class, and the sum of the times of all the pulse currents is only a few milliseconds), so that the rotor of the motor is almost stationary. In order to prevent sector position misjudgment caused by invalid pulse current collected when the current sampling module fails, in practical application, validity checks of time and pulse current can be added, for example, when the current sampling module is damaged, the obtained current value may exceed the standard instantaneously, or the preset current value may never be reached, so that the current value exceeding and the time overtime need to be judged at this time.

For example, a two-phase conduction method is still taken as an example. For example, when the time T _ AB required for the current value to reach the preset current value when the AB phase of the stator winding is turned on is obtained, at each current sampling, the difference between the sampled current value and the count value T1 'of the timer1 and the initial value T1 is determined, and if the sampled current value is not within the preset current range or the difference between T1' and T1 is not within the preset time range, an invalid sector is returned (obtained) to perform fault processing according to the invalid sector, and how to perform fault processing is specifically described, which is not described in detail herein; otherwise, continuing sampling until the current value of the stator winding reaches a preset current value, recording the count value of the timer at the moment, and further obtaining the time T _ AB required by the current value reaching the preset current value according to the count value of the timer.

And S2, acquiring a preset time-sector relation table according to the preset conduction mode.

In some embodiments of the present invention, when the predetermined conduction mode is a two-phase conduction mode, the predetermined time-sector relation table is shown in table 1:

TABLE 1

The time required for the current values of the stator windings in the AB phase, the BC phase, the CA phase, the BA phase, the CB phase and the AC phase to reach the preset current values is respectively T _ AB, T _ BC, T _ CA, T _ BA, T _ CB and T _ AC.

In other embodiments of the present invention, when the preset conduction mode is a three-phase conduction mode, the preset time-sector relation table is shown in table 2:

TABLE 2

Wherein, T _ A +, T _ B +, T _ C +, T _ A-, T _ B-and T _ C-are respectively the time required for the current values of the stator windings in the A + phase, the B + phase, the C + phase, the A-phase, the B-phase and the C-phase to reach the preset current value.

And S3, acquiring the sector where the rotor of the motor is located according to the plurality of times and a preset time-sector relation table, and acquiring the rotor position of the motor according to the sector where the rotor of the motor is located.

Specifically, after obtaining the plurality of times, it is determined whether the plurality of times satisfy the magnitude relationship in the corresponding time-sector relationship table, and if so, the sector where the rotor of the motor is located is obtained according to the time-sector relationship table. For example, when the two-phase conduction mode is adopted, if the relative magnitude relationship of a plurality of times satisfies table 1, the sector where the rotor of the motor is located can be determined according to table 1, that is, the rotor position of the motor is obtained. For example, when the six times T _ AB, T _ BC, T _ CA, T _ BA, T _ CB, and T _ AC satisfy the relationships (T _ BA < T _ CB) and (T _ CB < T _ AC) and (T _ BC < T _ AB) and (T _ AB < T _ CA), it is determined that the sector in which the rotor of the electric machine is located is the sector I.

When a three-phase conduction mode is adopted, if the relative magnitude relation of a plurality of times meets the table 2, the sector where the rotor of the motor is located can be determined according to the table 2, and the position of the rotor of the motor is obtained. For example, when six times T _ AB, T _ BC, T _ CA, T _ BA, T _ CB, and T _ AC satisfy the relationship (T _ B + < T _ a +) and (T _ a + < T _ C +) and (T _ a- < T _ B-) and (T _ B- < T _ C-), it is determined that the sector in which the rotor of the motor is located is the sector I.

In some embodiments of the present invention, when the plurality of times do not satisfy the preset time-sector relation table, the shortest time among the plurality of times is further acquired, the direction to be rotated of the motor is acquired, and the sector in which the rotor of the motor is located is acquired according to the shortest time and the direction to be rotated. The direction to be rotated comprises a clockwise rotation direction and a counterclockwise rotation direction.

That is, when the two-phase conduction mode is adopted, if the obtained plurality of times do not satisfy the relationship of table 1, the shortest time among the plurality of times is obtained, and then the sector where the rotor of the motor is located is determined according to the shortest time and the direction in which the motor needs to rotate; when a three-phase conduction mode is adopted, if the obtained plurality of times do not meet the relationship in the table 2, the shortest time in the plurality of times is obtained, and then the sector where the rotor of the motor is located is determined according to the shortest time and the direction in which the motor needs to rotate.

For example, table 3 and table 4 respectively show the sectors corresponding to the shortest time when the motor needs to rotate clockwise in the two-phase conduction mode and the three-phase conduction mode.

TABLE 3

Minimum time	Sector number
		Shortest of T _ BA	I
Shortest of T _ BC	III
		Shortest of T _ AC	II
Shortest of T _ AB	VI
		Shortest of T _ CB	IV
Shortest of T _ CA	V

TABLE 4

Minimum time	Sector number
		T _ B + shortest	I
T _ C-shortest	III
		T _ A + shortest	II
Tb-shortest	VI
		T _ C + shortest	IV
T _ A-shortest	V

Take two-phase conduction as an example. Assuming that the acquired six times T _ AB, T _ BC, T _ CA, T _ BA, T _ CB, and T _ AC do not satisfy the relationship of table 1 and the shortest time among the six times is T _ BC, when the motor rotates clockwise, as shown in table 3, it can be determined that the rotor position of the motor is in sector III. Thereby, the acquisition of the rotor position of the motor is achieved.

It should be noted that the phase (i.e. vector) and the sector number (sector number in tables 1 to 4) of the pulse injection are not necessarily and uniquely required, and actually, the sector number may be arbitrarily set as long as 6 sectors equally divided in a range of 360 ° can be distinguished.

Fig. 7 is a flowchart of a rotor positioning method of a brushless dc motor according to an embodiment of the present invention. As shown in fig. 7, the method for positioning the rotor of the brushless dc motor includes the following steps:

s101, selecting a vector in a two-phase conduction mode as a positioning pulse vector to position a rotor, and acquiring six time values and current values.

S102, checking the validity of the current value and the time. If both are valid, executing step S104; otherwise, step S103 is executed.

And S103, returning an invalid sector number.

S104, whether the time meets a predetermined time-sector relation table (such as table 1) is judged. If yes, go to step S106; otherwise, step S105 is performed.

S105, find the sector number corresponding to the shortest time (e.g., find the sector number corresponding to the shortest time from the preset table 2).

And S106, returning to the sector number of the rotor.

Therefore, according to the rotor positioning method of the brushless direct current motor, the time for starting and positioning the motor can be greatly shortened, the motor is prevented from reversing when being started, abnormal sound and jitter during positioning are solved, positioning errors caused by mismatching of current waveforms and rotor positions during pulse positioning are solved, the pulse positioning rotor position identification method is simplified, and full 360-degree blind-area-free positioning can be achieved.

Further, in some embodiments of the present invention, after obtaining the rotor position of the motor, the starting conduction phase of the stator winding at the time of starting the motor is also obtained according to the rotor position of the motor and the direction to be rotated of the motor. Specifically, according to the to-be-rotated direction of the motor, the starting conduction phase of the stator winding when the motor is started can be obtained by advancing by 90-120 degrees on the basis of the sector where the rotor of the motor is located.

For example, a two-phase conduction method is used to control the motor start. Tables 5 and 6 are respectively the start-up conduction phase tables for Clockwise (CW) and counterclockwise (CCW) in the two-phase conduction mode, where clockwise and counterclockwise refer to the direction of rotation of the phase vector and do not necessarily coincide with the actual direction of rotation of the motor shaft.

TABLE 5

TABLE 6

Sector number	Starting conducting phase
		I	CB phase
III	Phase of CA
		II	BA phase
VI	BC phase
		IV	AC phase
V	AB phase

As shown in tables 5 and 6, assuming that the sector in which the rotor of the motor is located is I, when the clockwise rotation of the motor is required, the starting conduction phase is an AC phase; when the motor is required to rotate anticlockwise, the starting conduction phase is a CB phase. Thus, clockwise and counterclockwise starting of the motor can be achieved according to tables 5 and 6.

According to one embodiment of the invention, the motor can be controlled to rotate clockwise and counterclockwise in any two opposite ways of three phases of the stator winding.

Specifically, the motor start is controlled in a two-phase conduction manner as an example. Clockwise and counter-clockwise rotation can also be used as follows: assuming that the rotor positions of the motor are obtained according to the sequence of AB, BC, CA, BA, CB, AC and tables 1 and 3, and the start-up conducting phase shown in table 5 is adopted for clockwise rotation, when counterclockwise rotation is required, any two of A, B and C phases specified in fig. 3 can be reversed, for example, the driving pins corresponding to the a phase and the C phase and the back-emf collecting channels of the a phase and the C phase are reversed, the rotor positions of the motor are still obtained according to the sequence of AB, BC, CA, BA, CB, AC and tables 1 and 3 in software, and the motor rotation is still controlled by adopting the start-up conducting phase shown in table 5, so that counterclockwise start-up of the motor can be realized. Namely, the positioning and starting of clockwise rotation and anticlockwise rotation can be realized by adopting any two opposite ways.

It should be noted that the motor start control in the three-phase conduction mode is similar to the motor start control in the two-phase conduction mode, and the details thereof are not described here.

In summary, according to the rotor positioning method of the brushless dc motor in the embodiment of the present invention, when conducting control is performed on the stator winding of the motor according to the preset conducting manner, voltage detection pulses are sequentially applied to different phases of the stator winding of the motor, and a plurality of times are obtained by obtaining a time required for a current value of the stator winding in each phase to reach the preset current value, and a preset time-sector relation table is obtained according to the preset conducting manner, and a sector where the rotor of the motor is located is obtained according to the plurality of times and the preset time-sector relation table, and a rotor position of the motor is obtained according to the sector where the rotor of the motor is located. Therefore, the time for starting and positioning the motor can be greatly shortened, the motor can not be reversely rotated when being started, abnormal sound and shaking during positioning are solved, the problem of positioning error caused by mismatching of current waveforms and rotor positions during pulse positioning can be solved, the pulse positioning rotor position identification method is simplified, and meanwhile, full 360-degree non-blind-area positioning can be realized.

In addition, an embodiment of the present invention further provides a non-transitory computer-readable storage medium, on which a computer program is stored, and the computer program, when executed by a processor, implements the rotor positioning method of the brushless dc motor described above.

Fig. 8 is a block diagram illustrating a rotor positioning apparatus of a brushless dc motor according to an embodiment of the present invention. As shown in fig. 8, the rotor positioning apparatus of the brushless dc motor according to the embodiment of the present invention may include: a given unit 10, a current acquisition unit 20, a time acquisition unit 30, and a control unit 40.

Wherein a given unit 10 is used to apply voltage detection pulses at different phases of the stator winding of the electrical machine; the current obtaining unit 20 is configured to obtain a current value of the stator winding at each phase; the time obtaining unit 30 is configured to obtain a time required for a current value of the stator winding in each phase to reach a preset current value; the control unit 40 is configured to, when conducting control is performed on the stator winding of the motor according to a preset conducting manner, sequentially apply voltage detection pulses to different phases of the stator winding of the motor through the given unit 10, obtain a time required for a current value of the stator winding in each phase to reach a preset current value through the time obtaining unit 30 to obtain a plurality of times, obtain a preset time-sector relation table according to the preset conducting manner, obtain a sector where a rotor of the motor is located according to the plurality of times and the preset time-sector relation table, and obtain a rotor position of the motor according to the sector where the rotor of the motor is located.

According to an embodiment of the present invention, when the predetermined conduction mode is a two-phase conduction mode, the predetermined time-sector relationship table is as follows:

According to another embodiment of the present invention, when the predetermined conduction mode is a three-phase conduction mode, the predetermined time-sector relationship table is as follows:

According to an embodiment of the present invention, when the plurality of times do not satisfy the preset time-sector relationship table, the control unit 40 further acquires the shortest time among the plurality of times, and acquires the direction to be rotated of the motor, and acquires the sector in which the rotor of the motor is located according to the shortest time and the direction to be rotated.

According to an embodiment of the present invention, after the time required for the current value of the stator winding at any one phase to reach the preset current value is acquired by the time acquisition unit 40, the control unit 40 further applies the reverse voltage detection pulse of the first preset time at any one phase by the giving unit 10 to cancel the energy accumulated on the stator winding by the voltage detection pulse.

It should be noted that details that are not disclosed in the rotor positioning device of the brushless dc motor according to the embodiment of the present invention refer to details disclosed in the rotor positioning method of the brushless dc motor according to the embodiment of the present invention, and detailed description thereof is omitted here.

In addition, an embodiment of the present invention further provides a control system of a brushless dc motor, which includes the above rotor positioning device of the brushless dc motor.

It should be understood that portions of the present invention may be implemented in hardware, software, firmware, or a combination thereof. In the above embodiments, the various steps or methods may be implemented in software or firmware stored in memory and executed by a suitable instruction execution system. For example, if implemented in hardware, as in another embodiment, any one or combination of the following techniques, which are known in the art, may be used: a discrete logic circuit having a logic gate circuit for implementing a logic function on a data signal, an application specific integrated circuit having an appropriate combinational logic gate circuit, a Programmable Gate Array (PGA), a Field Programmable Gate Array (FPGA), or the like.

In addition, in the description of the present invention, the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc. indicate orientations or positional relationships based on those shown in the drawings, and are only for convenience of description and simplicity of description, but do not indicate or imply that the device or element referred to must have a particular orientation, be constructed in a particular orientation, and be operated, and thus, should not be construed as limiting the present invention.

Furthermore, the terms "first", "second" and "first" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one such feature. In the description of the present invention, "a plurality" means at least two, e.g., two, three, etc., unless specifically limited otherwise.

In the present invention, unless otherwise expressly stated or limited, the terms "mounted," "connected," "secured," and the like are to be construed broadly and can, for example, be fixedly connected, detachably connected, or integrally formed; can be mechanically or electrically connected; they may be directly connected or indirectly connected through intervening media, or they may be connected internally or in any other suitable relationship, unless expressly stated otherwise. The specific meanings of the above terms in the present invention can be understood by those skilled in the art according to specific situations.

In the present invention, unless otherwise expressly stated or limited, the first feature "on" or "under" the second feature may be directly contacting the first and second features or indirectly contacting the first and second features through an intermediate. Also, a first feature "on," "over," and "above" a second feature may be directly or diagonally above the second feature, or may simply indicate that the first feature is at a higher level than the second feature. A first feature being "under," "below," and "beneath" a second feature may be directly under or obliquely under the first feature, or may simply mean that the first feature is at a lesser elevation than the second feature.

In the description herein, references to the description of the term "one embodiment," "some embodiments," "an example," "a specific example," or "some examples," etc., mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, the schematic representations of the terms used above are not necessarily intended to refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples. Furthermore, various embodiments or examples and features of different embodiments or examples described in this specification can be combined and combined by one skilled in the art without contradiction.

Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention, and that variations, modifications, substitutions and alterations can be made to the above embodiments by those of ordinary skill in the art within the scope of the present invention.

Claims

1. A rotor positioning method of a brushless direct current motor is characterized by comprising the following steps:

when conducting control is carried out on a stator winding of a motor according to a preset conducting mode, voltage detection pulses are sequentially applied to different phases of the stator winding of the motor, and a plurality of times are obtained by obtaining the time required by the current value of the stator winding at each phase to reach a preset current value, wherein the preset conducting mode comprises a two-phase conducting mode;

obtaining a preset time-sector relation table according to the preset conduction mode, wherein when the preset conduction mode is a two-phase conduction mode, the preset time-sector relation table is as follows:

relative magnitude of time relationship Sector number (T_BA<T _ CB) and (T _ CB)<T _ AC) and (T _ BC)<T _ AB) and (T _ AB)<T_CA) I (T_AC<T _ CB) and (T _ CB)<T _ BA) and (T _ BC)<T _ CA) and (T _ CA)<T_AB) III (T_AC<T _ BA) and (T _ BA)<T _ CB) and (T _ AB)<T _ CA) and (T _ CA)<T_BC) II (T_CB<T _ BA) and (T _ BA)<T _ AC) and (T _ AB)<T _ BC) and (T _ BC)<T_CA) VI (T_CB<T _ AC) and (T _ AC)<T _ BA) and (T _ CA)<T _ BC) and(T_BC<T_AB) IV (T_BA<t _ AC) and (T _ AC)<T _ CB) and (T _ CA)<T _ AB) and (T _ AB)<T_BC) V

The time required for the current values of the stator winding in the AB phase, the BC phase, the CA phase, the BA phase, the CB phase and the AC phase to reach the preset current value is respectively T _ AB, T _ BC, T _ CA, T _ BA, T _ CB and T _ AC;

and acquiring the sector where the rotor of the motor is located according to the plurality of times and the preset time-sector relation table, and acquiring the rotor position of the motor according to the sector where the rotor of the motor is located.

2. The method according to claim 1, wherein the predetermined conducting pattern further comprises a three-phase conducting pattern, and when the predetermined conducting pattern is the three-phase conducting pattern, the predetermined time-sector relationship table is as follows:

3. The method according to claim 2, wherein when the plurality of times do not satisfy the preset time-sector relationship table, the shortest time among the plurality of times is further obtained, the direction to be rotated of the motor is obtained, and the sector in which the rotor of the motor is located is obtained according to the shortest time and the direction to be rotated.

4. A rotor positioning method of a brushless dc motor according to any one of claims 1 to 3, wherein after acquiring a time required for a current value of the stator winding at any one phase to reach the preset current value, a reverse voltage detection pulse is further applied at the any one phase for a first preset time to cancel out an energy accumulated on the stator winding by the voltage detection pulse.

5. A non-transitory computer-readable storage medium, on which a computer program is stored, which, when being executed by a processor, implements a method for positioning a rotor of a brushless dc motor according to any one of claims 1-4.

6. A rotor positioning device for a brushless dc motor, comprising:

a given unit for applying voltage detection pulses at different phases of a stator winding of the motor;

the current obtaining unit is used for obtaining the current value of the stator winding at each phase;

the time acquisition unit is used for acquiring the time required by the current value of the stator winding at each phase to reach a preset current value;

the control unit is used for conducting control on the stator winding of the motor according to a preset conducting mode, applying voltage detection pulses sequentially at different phases of a stator winding of the motor by the given unit, and acquiring a time required for a current value of the stator winding at each phase to reach a preset current value through the time acquisition unit to obtain a plurality of times, and obtaining a preset time-sector relation table according to the preset conduction mode, obtaining a sector where a rotor of the motor is located according to the plurality of times and the preset time-sector relation table, and obtaining a rotor position of the motor according to the sector where the rotor of the motor is located, when the preset conduction mode is a two-phase conduction mode, the preset time-sector relation table is as follows:

7. The apparatus according to claim 6, wherein the predetermined conducting pattern further comprises a three-phase conducting pattern, and when the predetermined conducting pattern is the three-phase conducting pattern, the predetermined time-sector relationship table is as follows:

8. The apparatus according to claim 7, wherein when the plurality of times do not satisfy the preset time-sector relationship table, the control unit further obtains a shortest time among the plurality of times, obtains a direction to be rotated of the motor, and obtains a sector in which a rotor of the motor is located according to the shortest time and the direction to be rotated.

9. The rotor positioning apparatus of a brushless dc motor according to any one of claims 6 to 8, wherein the control unit further applies a reverse voltage detection pulse of a first preset time at any one phase by the given unit after acquiring a time required for a current value of the stator winding at the any one phase to reach the preset current value by the time acquisition unit to cancel energy accumulated on the stator winding by the voltage detection pulse.

10. A control system for a brushless dc motor, comprising a rotor positioning device for a brushless dc motor according to any one of claims 6 to 9.