Permanent magnet brushless motors have been widely used in various electrical applications such as three-phase pumps, fans, blowers, compressors, conveyor drives, etc. The drive power of the brushless motor is provided by the cutting effect of the permanent magnetic field from the permanent magnet and the variable electromagnetic field generated by coils or so called windings in the brushless motors. Compared to brushed motors, brushless motors as they contain no brush/commutator assembly provides higher efficiency, and reliability due to elimination of ionizing sparks from the commutators, A magnetic sensitive Hall effect component is installed in some brushless motors to collect signals of the permanent magnetic field, which are used as a reference for controlling the electrical power supplied to the windings of the motor.
However, there are also some drawbacks associated with existing brushless motors, one of which is that controllers for high power brushless motor, such as that used in electrically driven vehicle or hybrid electric-petroleum vehicles, are difficult to manufacture, due to the reason that the controller has to bear a large current which is required for generating high power output from the motor. Consequently, the manufacturing complexity for making a controller with high-power components results in high costs which is not desirable. In addition, failure or malfunctioning of the controller leads to interruption of the operation of the whole brushless motor with no backup option.
In the light of the foregoing background, it is an object of the present invention to obviate or mitigate to some degree one or more problems associated with known permanent magnet brushless motors.
The above object is met by the combination of features of the main claim; the sub-claims disclose further advantageous embodiments of the invention.
It is another object of the invention to provide an alternate brushless motor and a motor system consisted of brushless motors.
One skilled in the art will derive from the following description other objects of the invention. Therefore, the foregoing statements of object are not exhaustive and serve merely to illustrate some of the many objects of the present invention.
Accordingly, the present invention in one aspect discloses a brushless motor controller system, including a brushless motor which further contains a rotor and a stator, a plurality of independent motor controllers, a plurality of batteries, and a plurality of battery chargers. The stator of the brushless motor has a plurality of salient poles. A plurality of coils is wound on the plurality of salient poles such that on each of the plurality of salient poles there are wound different groups of windings electrically isolated from each other. The plurality of independent motor controllers each corresponds and electrically connected to one of the groups of windings on one the salient pole of the brushless motor. The plurality of batteries each is connected to a corresponding one of the independent motor controllers to provide electrical power thereto. The plurality of battery chargers each is connected to a corresponding one of the batteries. The plurality of independent motor controllers each is adapted to power and control a corresponding one of the groups of coils on one the salient pole in the brushless motor independently.
Preferably, the brushless motor also contains a plurality of sensing components configured to detect status of the rotor of the brushless motor.
Preferably, the sensing components are Hall sensors. The sensing components are configured such that each the sensing component detects a rotary orientation or position of the rotor in a different phase.
In one implementation, the status detected by at least one of the sensing components is shared by more than one of the plurality of independent motor controllers.
Preferably, the brushless motor in the motor controlling system is a three-phase brushless DC motor.
In an exemplary embodiment, the plurality of independent motor controllers are adapted to shut down one or more of the groups of coils in the brushless motor so that the brushless motor operates in a deducted power output mode.
In another aspect of the present invention, a method for controlling a brushless motor contains the steps of charging a plurality of batteries through a plurality battery chargers; supplying, from each one of the plurality of batteries, electrical power to a corresponding independent motor controller among a plurality of the independent motor controllers; and controlling a respective groups of windings in a brushless motor by each one of the independent motor controllers.
Preferably, in the method above the brushless motor further contains a plurality of sensing components configured to detect status of a rotor of the brushless motor.
Preferably, the sensing components are Hall sensors. The above method further includes the steps of detecting, by each sensing components, a rotary orientation or position of the rotor of the motor in a different phase; and transmitting information containing the rotary orientation or position of the rotor detected by one the sensing component to more than one the independent motor controllers.
In one implementation, the brushless motor in the above method is a three-phase brushless DC motor.
Preferably, in the method mentioned above the plurality of independent motor controllers are adapted to shut down one or more of the groups of windings in the brushless motor so that the brushless motor operates in a deducted power output mode.
There are many advantages to the present invention. Firstly, by inserting the permanent magnets into the cavities under the surface of the rotor core, the permanent magnets are steadily fixed within the rotor, as a result of which the risk of permanent magnet detachment is eliminated or substantially reduced. On the other side, the lines of magnetic force around the rotor are distributed more evenly due to the positions of the permanent magnets, which improve the energy conversion efficiency and in turn increase the overall performance of the electric motor. Grooves are provided between two magnetized surfaces or essentially two permanent magnets on the rotor. The grooves on the rotor generate air flow when the electric brushless motor is operating, so that heat accumulated in or around the coils on the salient poles and around the motor can be effectively dissipated.
Another advantage of the present invention is that in the motor system as described in embodiments of the present invention there are provided a variety of structures such as more than one controller separately controlling the coils on the stator, or more than one controller separately controlling brushless motors in the motor system. These structures have been adopted to separately control the coils / motors in the system, so that flexible power output of the motor system can be realized, and it is much simpler to manufacture more than one small power controller rather than a single high power controller, while the desired high drive power output could still be achieved. On the other hand, the motor system is capable of achieve energy-saving when the target device does not require the full output power of the motor system.
The foregoing and further features of the present invention will be apparent from the following description of preferred embodiments which are provided by way of example only in connection with the accompanying figures, of which:
In the claims which follow and in the preceding description of the invention, except where the context requires otherwise due to express language or necessary implication, the word “comprise” or variations such as “comprises” or “comprising” is used in an inclusive sense, i.e. to specify the presence of the stated features but not to preclude the presence or addition of further features in various embodiments of the invention.
As used herein and in the claims, “couple” or “connect” refers to electrical coupling or connection either directly or indirectly via one or more electrical means unless otherwise stated.
Referring now to
On the inner circumference of the stator 22, there are formed a plurality of salient poles 32 on each of which a coil (not shown) is wound. The plurality of salient poles 32 opposite to the magnetized surfaces 40 on the rotor 24. In one embodiment, the number of salient poles 32 on the stator 22 is an even number. Preferably, the salient poles 32 are evenly distributed on the inner circumference of the stator 24 and equidistant to each other at predetermined intervals. Optionally, there are also one or more Hall effect sensors 30 installed on the salient poles 32.
In the embodiment as shown in Fig. la, there are 18 salient poles 32 on the inner circumference of the stator 22, and correspondingly 16 magnetic steels 26 on the outer circumference of the rotor 24. The 18 salient poles 32 are equally divided into two groups of three-phase windings along the inner circumference of the stator 22, namely the first winding 34 and the second winding 36. In other words, each one of the first winding 34 and the second winding 36 contains 9 salient poles. Both the first winding 34 and the second winding 36 are full-pitch windings, which means that in each three-phase winding containing 9 salient poles, a first-phase coil winds in the positive direction around a first salient pole, then winds one extra turn in the negative direction around a third salient pole, and then exits from a second salient pole between the first salient pole and the third salient pole; a second-phase coil winding in the positive direction around a fourth salient pole, then winding one extra turn in the negative direction around a sixth salient pole, and then exiting from a fifth salient pole between the fourth salient pole and the sixth salient pole; a third-phase coil winding in the positive direction around a seventh salient pole, then winding one extra turn in the negative direction around a ninth salient pole, and then exiting from a eighth salient pole between the seventh salient pole and the ninth salient pole. The same coils configuration applies to the other three-phase winding. As shown in
Now turning to the operation of the device described above, the brushless motor as shown in
The silicon steel sheet inserted into the magnetic steel 26 protects the magnetic steel 26 from magnetic field leakage. The Hall effect sensors or in short Hall sensors 30 installed on the salient poles 32 of the brushless motor detects the position as well as the rotating speed of the rotor 24 and feed that information to an external motor controller (not shown) connected to the motor via the cable assembly 46 as mentioned above. Mounting more than one Hall effect sensors 30 on the corresponding salient poles 32 provides better detection results to the Hall effect sensors 30 as the magnetic fields would be detected at different places. Preferably, the Hall effect sensors 30 are also divided into three groups to provide status information for each phase of the three-phase motor. The output of the Hall effect sensors 30 provided to the remote motor controller may be further analyzed using computer software.
Further, the salient poles in the above embodiments of the motor are equally divided into two groups of three-phase windings, and each three-phase winding may be connected to a separate motor controller, which means that the total electrical current bear by the brushless motor is also equally shared by the two motor controller. This composite magnetic flux configuration eliminates the need of producing a single, high-power motor controller, but instead it is much simpler to manufacture more than one small power controllers to control the motor, while the desired high drive power output of the motor could still be achieved. As there is more than one motor controller, the total current supplied to the motor is flexible and could be adjusted depending on a specific application, such as where a high output torque is required.
In another embodiment of the present invention as shown in
In operation, as the first coil 104 and second coil 106 are independent to each other, the brushless motor as shown is capable of providing electric power only to the first coil 104, second coil 106, or both. For instance, when the target device only requires a relatively small driving force, the first controller 100 may provide electricity to the first coil 104, and the magnetic fields generated by the first coil 104 and the rotor drive the shaft of the motor to rotate, in order to produce a relatively small driving force. At this time the second coil 106 is not supplied with electricity and thus there is no magnetic field generated by the second coil 106. On the other hand, when the target device requires a relatively large driving force, then both the first controller 100 and the second controller 102 may provide electricity to the first coil 104 and the second coil 106 at the same time. The rotor then reacts with both the magnetic fields from the first coil 104 and the second coil 106, and thus the total driving force outputted by the motor is large.
The brushless motor according to the present invention may further be implemented to contain similar structures as that described in
Referring now to the main controllers 200 and 202, each of them further contains three independent controllers 203 that are accommodated in a single device housing of the controller 200 or 202. Each of the independent controllers 203 correspond and electrically connected to a respective battery 204 that is placed outside of the main controller 200 or 202. As shown in
Turning to
In the configuration shown in
Now turning to the operation of the motor controlling system described above, the motor controller system receives external AC power from an external power input 206 such as a power cable connected to 110V/220V AC electricity. The AC power is then provided to the plurality of battery chargers 205 which covert the AC electricity to DC power and charge the batteries 204 on a one-to-one basis. Each of the batteries 204 is adapted to drive its corresponding independent motor controller 203 which in turn drives a corresponding set of independent coils in the motor 201. The six independent controllers 203 can individually controls its counterpart set of coils in the motor 201, so that different power output achieved by the six set of independent coils in the motor 201 as a whole can be achieved. For example, in a lower power output application each of the motor independent controllers 203 may only outputs a small amount of current. Alternatively, the plurality of independent motor controllers 203 are adapted to shut down one or more of the sets of coils in the brushless motor 201 so that the brushless motor operates in a deducted power output mode. In contrast, when the motor 201 is required to operate in a full throttle condition, each of the independent controllers 203 outputs a maximum allowed amount to their corresponding coil windings so that the total power output achieved by the motor 201 is maximum.
One exemplary application of the brushless DC motor controller system illustrated in
Another advantage of the distributed motor controllers, batteries and batteries controllers in the field of electrically driven vehicles is that these components are now produced to be discrete parts, which means that they can be separated from each other to be placed into different locations of the vehicle. This provides much more design freedoms to the vehicle designers so they do not have to consider reserving a large inner space of the vehicle for storing the motor controller or the battery. Instead, following the desired aesthetic design of the vehicle body the individual batteries and motor controllers can be placed at different locations so that the performance of the power system of the vehicle is not compromised but at the same time the components can be distributed to save space and conform to the overall contour of the vehicle.
While the invention has been illustrated and described in detail in the drawings and foregoing description, the same is to be considered as illustrative and not restrictive in character, it being understood that only exemplary embodiments have been shown and described and do not limit the scope of the invention in any manner. It can be appreciated that any of the features described herein may be used with any embodiment. The illustrative embodiments are not exclusive of each other or of other embodiments not recited herein. Accordingly, the invention also provides embodiments that comprise combinations of one or more of the illustrative embodiments described above. Modifications and variations of the invention as herein set forth can be made without departing from the spirit and scope thereof, and, therefore, only such limitations should be imposed as are indicated by the appended claims.
It is to be understood that, if any prior art publication is referred to herein, such reference does not constitute an admission that the publication forms a part of the common general knowledge in the art, in Australia or any other country.
For example, the permanent magnetic bodies in the brushless motor are magnetic steels with silicon steel sheet inserted in the magnetic steels. The rotor core of the motor is made of a stack of silicon steel sheets. However, one skilled in the art should realize that the magnetic bodies or the rotor core may be fabricated using any other suitable materials/configurations, as long as these materials/configurations are capable of providing the desired performance.
In a preferred embodiment described above there are 18 salient poles and 16 magnetic steels in the brushless motor. But in other applications, the brushless motor may contain any number of poles and magnetic bodies, provided that the number of the magnetic bodies is an even number and the commutation condition can be satisfied. In one implementation, the number of the salient poles could be an even number or an odd number, and the number of magnetic steels must be an even number.
The embodiments illustrated in
The above embodiments were described using a brushless motor. However, one skilled in the art would appreciate that the teachings of the present invention may also be applicable to other types of motors such as brushed motors or AC synchronized motors.
In the embodiment described in
Also, in the embodiment shown in
Filing Document | Filing Date | Country | Kind |
---|---|---|---|
PCT/CN2014/076393 | 4/28/2014 | WO | 00 |