Patent Application
20170163183
This non-provisional patent application claims priority to Chinese Patent Application No. CN201510894852.4, filed with the Chinese Patent Office on Dec. 7, 2015 which is incorporated herein by reference in their entirety.
The present disclosure relates to a control system, and in particular to a motor control system, a motor control method and a vacuum cleaner including the motor control system, which can improve efficiency.
At present, motors have been applied to various household appliances, such as a vacuum cleaner, as power sources. In general, household appliances such as a vacuum cleaner need to be driven by motors operating at high rotational speeds. As a rotational speed of a motor increases, a back electromotive force increases as well, which reduces utilization efficiency of a power supply for the motor.
The present disclosure is further described hereinafter in conjunction with drawings in the specification and some embodiments.
Referring to
The motor control system 1 further excites the motor within a conduction angle, and the motor control system 1 gradually reduces the conduction angle to a pre-determined value during the process from the acceleration mode to the constant speed operating mode after the motor 3 is started. The conduction angle refers to an angle from starting of excitation to finishing of the excitation in a half-electric-cycle in which the motor 3 is powered on.
In a half-electric-cycle, the motor control system 1 controls the motor 3 to freewheel after the conduction angle. Therefore, in a half-electric-cycle, the motor control system 1 controls the motor 3 to be sequentially excited and freewheeled.
The advance angle is set and selected to maximize torque which is applied to the motor 3 at the beginning of each excitation, so as to improve efficiency of the motor 3.
Referring also to
As shown in
The drive controller 30 further enables, based on the drive signal generated based on the detection signal of the position sensor 20, the inverter 10 to establish a first power supply path between the power supply 2 and the motor 3 in advance of a zero crossing of the back electromotive force by the advance angle, so the motor 3 is excited in advance with an excitation current in a first direction; and establish a second power supply path between the power supply 2 and the motor 3 in advance of a next zero crossing of the back electromotive force by the advance angle, so the motor 3 is excited in advance with the excitation current in a second direction. In this way, the inverter 10 alternately establishes the first power supply path and the second power supply path between the power supply 2 and the motor 3 to alternately change a direction of the excitation current, so that a direct current provided by the power supply 2 is inverted into an alternating current to drive the motor 3 to keep operating.
A half-electric-cycle lasts from motor 3 receives the excitation current to the excitation current changes the direction. In each half-electric-cycle, the motor 3 is excited and freewheeled in order.
Referring also to
In the first supply path, the positive terminal 21 and the negative terminal 22 of the power supply 2 are connected to the first electrode terminal 33 and the second electrode terminal 34 respectively. In the second supply path, the positive terminal 21 and the negative terminal 22 of the power supply 2 are connected to the second electrode terminal 34 and the first electrode terminal 33 respectively
In the embodiment, the rotor 32 is a permanent magnet and is rotatable relative to the stator 31. The position sensor 20 is arranged near the motor 3, and generates, by detecting a position of the rotor 32, a detection signal including the back electromotive force passes the zero crossing. Specifically, when the position sensor 20 detects a magnetic pole N or a magnetic pole S, a level of the generated detection signal changes and an edge is formed, where the edge indicates that the back electromotive force in the motor 3 passes the zero crossing at this moment.
As shown in
The drive controller 30 is connected to the first semiconductor switch Q1, the second semiconductor switch Q2, the third semiconductor switch Q3 and the fourth semiconductor switch Q4. The drive controller 30 is configured to output four drive signals S1 to S4 to respectively control the first semiconductor switch Q1, the second semiconductor switch Q2, the third semiconductor switch Q3 and the fourth semiconductor switch Q4. In the embodiment, the first semiconductor switch Q1, the second semiconductor switch Q2, the third semiconductor switch Q3 and the fourth semiconductor switch Q4 are switches turned on at high levels. In the embodiment, the first semiconductor switch Q1, the second semiconductor switch Q2, the third semiconductor switch Q3 and the fourth semiconductor switch Q4 are NMOSFET; or, some are NMOSFET and the others are IGBT or NPNBJT.
Referring also to
As shown in
The drive controller 30 further controls the drive signal S1 to jump to a low level, the drive signal S2 to jump to a high level, the drive signal S3 to remain at the low level, and the drive signal S4 to remain at the high level after the excitation voltage is applied for a conduction angle θcon. In this case, the first semiconductor switch Q1 and the third semiconductor switch Q3 are turned off, the second semiconductor switch Q2 and the fourth semiconductor switch Q4 are turned on, the connection between the stator 31 of the motor 3 and the power supply 2 is cut off. The stator 31 of the motor 3 forms a freewheeling circuit to be freewheeled within a freewheeling angle θfre with the second semiconductor switch Q2 and the fourth semiconductor switch Q4 which are turned on.
The drive controller 30 determines a position of the advance angle θadv before the current edge E1 based on a previous edge (i.e., an edge before the edge E1) of the detection signal H1. Apparently, in a half-electric-cycle, (180°−θadv) is an angle between the previous edge and the advance angle θadv (the timing for starting the excitation in advance). The drive controller 30 controls the drive signal S1 to jump to a high level at a point of the advance angle θadv in advance of the edge E1 of the detection signal H1, the drive signal S2 to jump to a low level at a point of the advance angle θadv in advance of the edge E1 of the detection signal H1, the drive signal S3 to remain at the low level, and the drive signal S4 to remain at the high level. That is, at a point (180°−θadv) after the previous edge before the edge El of the detection signal H1, the drive controller 30 controls the drive signal S1 to jump to the high level, the drive signal S2 to jump to the low level, the drive signal S3 to remain at the low level, and the drive signal S4 to remain at the high level.
In the embodiment, both the conduction angle θcon and the advance angle θadv are related to a speed and may be obtained from a look-up table. For example, a relation of speeds versus conduction angles θcon and advance angles θadv is recorded in a look-up table. A corresponding conduction angle θcon and a corresponding advance angle θadv can be found in the look-up table based on a current speed. Based on the conduction angle θcon=θadv+θdrv, it can be obtained that: θdrv=θcon−θadv, where θdrv, is a drive angle for which the excitation lasts after the edge E1 of the detection signal. Therefore, the drive controller 30 controls, after the excitation voltage is applied for the conduction angle θcon, the drive signal S1 to jump to a low level, the drive signal S2 to jump to a high level, the drive signal S3 to remain at the low level, and the drive signal S4 to remain at the high level. That is the motor 3 is kept excited within the drive angle θdrv after the edge E1 of the detection signal H1, the drive signal S1 is controlled to jump to the low level after the drive θdrv, the drive signal S2 is controlled to jump to the high level, the drive signal S3 is controlled to remain at the low level, and the drive signal S4 is controlled to remain at the high level.
A sum of the conduction angle θcon and the freewheeling angle θfre is a half-electric-cycle, i.e., θcon+θfre=180°. Hence, the freewheeling angle θfre may be obtained based on: θfre=180°−θcon.
In this way, the drive controller 30 generates the drive signals S1 to S4 based on the detection signal generated by the position sensor 20, the motor 30 is excited in advance of the edge of the detection signal by the advance angle θadv and freewheeled after the excitation for the conduction angle θcon.
The drive controller 30 switches the supply path after the freewheeling is performed for the freewheeling angle θfre, i.e., switching the direction of the excitation voltage to enter a next half-electric-cycle, and a process similar to the foregoing process is performed. Specifically, the drive controller 30 controls the drive signal S3 to jump to a high level in advance of a next edge E2 of the detection signal H1 by the advance angle θadv, controls the drive signal S4 to jump to a low level, controls the drive signal S1 to remain at the low level, and controls the drive signal S2 to remain at the high level. In this case, the third semiconductor switch Q3 and the second semiconductor switch Q2 respectively controlled by the drive signal S3 and the drive signal S2 are turned on, the first semiconductor switch Q1 and the fourth semiconductor switch Q4 respectively controlled by the drive signals S1 and S4 are turned off, and the excitation voltage applied to the motor 3 is inverted, to continue driving the rotor 32 of the motor 3 to rotate in the same direction. Similarly, after the inverted excitation voltage is applied for the conduction angle θcon, the drive controller 30 controls the drive signal S1 to remain at the low level, the drive signal S2 to remain at the high level, the drive signal S3 to jump to a low level and the drive signal S4 to jump to a high level. In this case, the first semiconductor switch Q1 and the third semiconductor switch Q3 are turned off, the second semiconductor switch Q2 and the fourth semiconductor switch Q4 are turned on, and the stator 31 of the motor 3 forms a freewheeling circuit to perform freewheeling within the freewheeling angle θfre with the second semiconductor switch Q2 and the fourth semiconductor switch Q4.
Similar to the previous half-electric-cycle, in advance of a next edge E2 of the detection signal H1 by the advance angle θadv, the drive signal S3 to jump to a high level, the drive signal S4 is controlled to jump to a low level, the drive signal S1 is controlled to remain at the low level, and the drive signal S2 is controlled to remain at the high level. That is at a point (180°−θadv) after the current edge E1, the drive signal S3 is controlled to jump to the high level, the drive signal S4 is controlled to jump to the low level, the drive signal S1 is controlled to remain at the low level, and the drive signal S2 is controlled to remain at the high level. Similarly, after the inverted excitation voltage is applied for the conduction angle θcon, the drive controller 30 controls the drive signal S1 to remain at the low level, the drive signal S2 to remain at the high level, the drive signal S3 to jump to a low level and the drive signal S4 to jump to a high level. That is keeping be excited within the drive angle θdrv after the next edge E2 of the detection signal H1, and controlling the generated drive signal S1 to remain at the low level, the drive signal S2 to remain at the high level, the drive signal S3 to jump to the low level and the drive signal S4 to jump to the high level after the drive angle θdrv.
As shown in
The position sensor 20 is a Hall sensor, and the generated detection signal H1 is a Hall signal. Variation in edge occurs in the Hall signal when the magnetic pole N or the magnetic pole S is in the vicinity, so that an edge is formed.
In the embodiment, the advance angle θadv varies in a range from zero degree to 30°. That is, during the process of the motor 3 switching from the acceleration mode to the constant speed operating mode, the advance angle θadv gradually increases from zero degree to 30°. The conduction angle θcon may vary in a range from 180°-108°. That is, during a process of the motor 3 starting, entering the acceleration mode and the constant speed operating mode, the conduction angle gradually decreases from 180° to 108°. That is, during the process of the motor 3 starting, entering the acceleration mode and the constant speed operating mode, excitation is performed from within a whole half-electric-cycle to only within 108°.
As shown in
There is a response time between applying the drive signals to the semiconductor switches in the inverter 10 and actual responding of the semiconductor switches, for example, actually being turned on or turned off. In a case that the speed of the rotor 32 of the motor 3 is very low, the response time may be ignored. In a case that the speed of the rotor 32 of the motor 3 is very high, for example, reaching 10 W rpm (revolutions per minute), the response speed may cause great influence. Therefore, in the present disclosure, by gradually increasing the advance angle as the speed of the rotor of the motor 3 increases, the rotor 32 can always reach a pre-determined position where the torque is the maximum when the semiconductor switches actually respond to the applied drive signals, which can improve efficiency of the motor 3. By gradually reducing the conduction angle, freewheeling can be performed within the freewheeling angle, in a case that the excitation voltage is difficult to apply due to the increasing back electromotive force caused by the increasing speed, thus eliminating effect of the back electromotive force to a certain extent.
Referring to
Therefore, in order to avoid the above situation, in the embodiment, in a case that two semiconductor switches in the same half-bridge are required to be respectively turned on and turned off around the same time, the drive controller 30 turns off a semiconductor switch which is to be turned off, and then turns on a semiconductor switch in the same half-bridge which is to be turned on after delaying for a delay angle. In the embodiment, an instant in which the two semiconductor switches in the same half-bridge are required to be respectively turned on and turned off around the same time is an instant for inverting the excitation voltage provided for the motor 3 (i.e., an instant from which the excitation voltage is inverted, which may also be referred to as an instant for starting to provide the excitation voltage in a case that a freewheeling angle exists) or an instant for performing freewheeling on the motor 3 (i.e., an instant from which the freewheeling is performed). The delay angle is very small, for example, 0.1°. Therefore, the two semiconductor switches in the same half-bridge still can be regarded as being respectively turned on and turned off around the same time. Since a turn-on instant of a semiconductor switch to be turned on is later than/delayed from a turn-off instant of a semiconductor switch to be turned off, a situation in which two semiconductor switches in the same half-bridge are turned on at the same time is avoided.
As shown in
In the embodiment, the drive controller 30 controls, after the excitation voltage is applied for the conduction angle θcon, the generated drive signal S1 to jump to a low level, the drive signal S3 to remain at the low level, and the drive signal S4 to remain at the high level, and controls the drive signal S2 to jump to a high level after delaying for the delay angle θdey. In this way, for the first semiconductor switch Q1 and the second semiconductor switch Q 2 which need to change states, it still can be ensured that the first semiconductor switch Q1 is turned off before the second semiconductor switch Q2 is turned on, avoiding a situation in which the two semiconductor switches are simultaneously turned on.
As shown in
Positional relationships between the elements shown in the drawings of the present disclosure are merely electrical and logical positional relationships rather than representing a positional arrangement of the elements in a product.
Reference is made to
In step 601, when an excitation voltage for a motor is inverted or the motor is freewheeled, the drive controller turns off one semiconductor switch firstly.
In step 503, the drive controller turns on the other semiconductor switch after delaying for a delay angle in same half-bridge.
The foregoing embodiments are only some preferred embodiments of the invention and are not intended to limit the invention in any form. In addition, changes can be made by those skilled in the art within the spirit of the present disclosure. Of course, those changes made based on the spirit of the present disclosure shall fall within the protection scope claimed by the present disclosure.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2015 1089 4852.4 | Dec 2015 | CN | national |
