阅读说明：本技术 容错永磁直流马达驱动器 (Fault tolerant permanent magnet DC motor drive ) 是由 J·M·胡 P·普拉莫德 M·R·伊斯兰 于 2017-11-29 设计创作，主要内容包括：描述了用于生成多绕组PMDC马达的输出转矩的技术方案。一种示例方法包括由电流控制器生成针对PMDC马达的多个绕组集中的第一绕组集的第一电压命令,该第一绕组集响应于第一电压命令而生成第一电流。该方法还包括由电流控制器生成针对PMDC马达的绕组集中的第二绕组集的第二电压命令,该第二绕组集响应于第二电压命令而生成第二电流。该方法还包括由PMDC马达基于第一电流和第二电流生成输出转矩。(A solution for generating an output torque of a multi-winding PMDC motor is described. An example method includes generating, by a current controller, a first voltage command for a first winding set of a plurality of winding sets of a PMDC motor, the first winding set generating a first current in response to the first voltage command. The method also includes generating, by the current controller, a second voltage command for a second winding set of the PMDC motor, the second winding set generating a second current in response to the second voltage command. The method also includes generating, by the PMDC motor, an output torque based on the first current and the second current.)

1. A system, comprising:

a permanent magnet direct current PMDC motor comprising a plurality of winding sets:

a first winding set comprising a first pair of poles, a first pair of brushes, and a first winding; and

a second winding set comprising a second pair of poles, a second pair of brushes, and a second winding; and a controller configured to cause the PMDC motor to generate a predetermined amount of torque by:

applying a first voltage command to the first winding set, the first winding set generating a first current in response to the first voltage command;

applying a second voltage command to the second winding set, the second winding set generating a second current in response to the second voltage command; and

the first current and the second current cause the motor to generate the predetermined amount of torque.

2. The system of claim 1, further comprising: a plurality of power converters, wherein each power converter corresponds to a respective winding set.

3. The system of claim 2, wherein the controller comprises a plurality of controllers, wherein each controller corresponds to a set of windings, wherein a first controller is to generate the first voltage command for the first set of windings and a second controller is to generate the second voltage command for the second set of windings.

4. The system of claim 1, further comprising: a plurality of power converters, wherein each group of power converters corresponds to a respective winding set.

5. The system of claim 4, wherein the controller comprises: a plurality of controllers, wherein each group of controllers corresponds to a winding set.

6. The system of claim 1, wherein the controller comprises a plurality of controllers, wherein each controller corresponds to a set of windings, wherein a first controller is to generate the first voltage command for the first set of windings and a second controller is to generate the second voltage command for the second set of windings.

7. The system of claim 1, wherein the first winding set has a first pair of terminals and the second winding set has a second pair of terminals, wherein the first pair of terminals lead from the first pair of brushes and the second pair of terminals lead from the second pair of brushes.

8. The system of claim 1, wherein, in response to a brush failure of the first winding set, the controller skips generating the first voltage command and continues to generate the second voltage command for the second winding set.

9. A permanent magnet direct current PMDC motor comprising:

a plurality of winding sets comprising:

a first winding set comprising a first pair of poles, a first pair of brushes, and a first winding; and

a second winding set comprising a second pair of poles, a second pair of brushes, and a second winding;

wherein the first winding set generates a first current command in response to a first voltage command from a controller; and

the second winding set generates a second current command in response to a second voltage command from the controller.

10. The PMDC motor of claim 9, further comprising: a plurality of power converters, wherein each power converter corresponds to a respective set of windings.

11. The PMDC motor of claim 10, wherein the controller comprises a plurality of controllers, wherein each controller corresponds to a winding set, a first controller for generating the first voltage command for the first winding set, and a second controller for generating the second voltage command for the second winding set.

12. The PMDC motor of claim 9, further comprising: a plurality of power converters, wherein each group of power converters corresponds to a respective winding set.

13. The PMDC motor of claim 12, wherein the controller comprises: a plurality of controllers, wherein each group of controllers corresponds to a winding set.

14. The PMDC motor of claim 9, wherein the controller comprises a plurality of controllers, wherein each controller corresponds to a winding set, wherein a first controller is configured to generate the first voltage command for the first winding set and a second controller is configured to generate the second voltage command for the second winding set.

15. The PMDC motor of claim 9, wherein the first winding set has a first pair of terminals and the second winding set has a second pair of terminals, wherein the first winding set has a first power converter and the second winding set has a second power converter.

16. A method for generating an output torque of a multi-winding PMDC motor, the method comprising:

generating, by a current controller, a first voltage command for a first winding set of a plurality of winding sets of the PMDC motor, the first winding set generating a first current in response to the first voltage command; and

generating, by the current controller, a second voltage command for a second winding set of the plurality of winding sets of the PMDC motor, the second winding set generating a second current in response to the second voltage command; and

generating, by the PMDC motor, the output torque based on the first current and the second current.

17. The method of claim 16, wherein the PMDC motor is associated with a plurality of power converters, wherein each power converter corresponds to a respective set of windings of the PMDC motor.

18. The method of claim 17, wherein the current controller comprises a plurality of controllers, wherein each controller corresponds to a winding set, a first controller to generate the first voltage command for the first winding set, and a second controller to generate the second voltage command for the second winding set.

19. The method of claim 16, wherein the PMDC motor is associated with a plurality of power converters, wherein each set of power converters corresponds to one respective winding set.

20. The method of claim 16, wherein in response to a brush failure of the first winding set, the controller skips generating the first voltage command and continues to generate the second voltage command for the second winding set.

Background

The present application relates generally to permanent magnet direct current motor (PMDC motor) drives and, more particularly, to fault tolerant operation of PMDC motor drives.

There is an increasing need for fault tolerant operation of safety critical systems such as those involved in automotive subsystems including Electric Power Steering (EPS) and Automatic Driving Assistance Systems (ADAS). This requirement triggers the introduction of redundancy in the electromechanical motion control system, achieving improved fault tolerance and thus fail-safe operation. An electric drive system typically includes an electric motor, one or more power converters and sensors, as well as other components for facilitating operation of the motion control system.

Accordingly, it is desirable to introduce redundancy in the drive system to improve the fault tolerance of the automotive subsystems and other components using such electric drive systems.

Disclosure of Invention

In accordance with one or more embodiments, a system includes a Permanent Magnet Direct Current (PMDC) motor including a plurality of winding sets. A first winding set of the plurality of winding sets includes a first pair of poles, a first pair of brushes, and a first winding. Further, a second winding set of the plurality of winding sets includes a second pair of poles, a second pair of brushes, and a second winding. The system also includes a controller that causes the PMDC motor to generate a predetermined amount of torque by applying a first voltage command to a first winding set, wherein the first winding set generates a first current in response to the first voltage command, and the controller causes the PMDC motor to generate the predetermined amount of torque by applying a second voltage command to a second winding set, wherein the second winding set generates a second current in response to the second voltage command. The first current and the second current cause the motor to generate a predetermined amount of torque.

In accordance with one or more embodiments, a Permanent Magnet Direct Current (PMDC) motor includes a plurality of winding sets. A first winding set of the plurality of winding sets includes a first pair of poles, a first pair of brushes, and a first winding. A second winding set of the plurality of winding sets includes a second pair of poles, a second pair of brushes, and a second winding. The first winding set generates a first current command in response to a first voltage command from the controller. The second winding set generates a second current command in response to a second voltage command from the controller.

In accordance with one or more embodiments, a method for generating an output torque of a multi-winding PMDC motor includes: a first voltage command is generated by a current controller for a first winding set of a plurality of winding sets of the PMDC motor, wherein the first winding set generates a first current in response to the first voltage command. The method also includes generating, by the current controller, a second voltage command for a second winding set of the plurality of winding sets of the PMDC motor, wherein the second winding set generates a second current in response to the second voltage command. The method also includes generating, by the PMDC motor, an output torque based on the first current and the second current.

These and other advantages and features will become more apparent from the following description taken in conjunction with the accompanying drawings.

Drawings

The subject matter which is regarded as the invention is particularly pointed out and distinctly claimed in the claims at the conclusion of the specification. The foregoing and other features and advantages of the disclosure will become apparent from the following detailed description taken in conjunction with the accompanying drawings, in which:

FIG. 1 is an exemplary embodiment of a vehicle 10 including a steering system;

FIG. 2 depicts a configuration of a PMDC machine in accordance with one or more embodiments;

FIG. 3 depicts another configuration of a PMDC machine in accordance with one or more embodiments;

FIG. 4 depicts an example multi-winding PMDC machine in accordance with one or more embodiments;

FIG. 5 depicts a block diagram of a dual winding PMDC machine using a mathematical model in accordance with one or more embodiments;

FIG. 6 depicts an example multi-winding PMDC machine in accordance with one or more embodiments;

FIG. 7 depicts an example system 700 using a multi-winding PMDC machine in accordance with one or more embodiments;

FIG. 8 depicts an example fault tolerant system in accordance with one or more embodiments; and

fig. 9 illustrates a flow diagram of an example method for providing fault tolerance in a PMDC motor control system using a multi-winding PMDC motor in accordance with one or more embodiments.

FIG. 10 depicts an example fault tolerant system architecture in accordance with one or more embodiments.

Detailed Description

The terms "module" and "sub-module" are used herein to refer to one or more processing circuits (e.g., an Application Specific Integrated Circuit (ASIC), an electronic circuit), a processor (shared, dedicated, or group) and memory that execute one or more software or firmware programs, a combinational logic circuit, and/or other suitable components that provide the described functionality. It is understood that the sub-modules described below may be combined and/or further partitioned.

Permanent Magnet Direct Current (PMDC) motors are widely used in automotive applications, such as Electric Power Steering (EPS) systems. A PMDC motor has three main components, namely a stator, a rotor and a commutator. Typically, the stator contains poles and the rotor is an armature that carries windings. A commutator is attached to the brushes and slip rings to allow the machine to mechanically commutate. Here, the machine may be the PMDC motor itself, or may be a system employing the PMDC motor, such as an EPS system. The brushes are connected to a phase terminal through which a voltage can be applied to the machine. Brushes are generally susceptible to mechanical wear. Mechanical wear may cause the PMDC motor to fail, after which the machine will fail to operate. In an EPS system setting, not using a PMDC motor can result in the driver losing assistance. In addition to the motor, the power converter circuit and the microcontroller (logic) board used to control the electric drive system are also prone to failure.

The technical solution described herein addresses the above-mentioned technical challenges by including in the PMDC machine a technique for introducing redundancy and a control architecture that involves redundancy in the power converter and logic circuits to facilitate PMDC-based electric drive system fault tolerance. In addition, the technical scheme also provides an analysis model of the PMDC machine. It should be noted that various embodiments of the solution described herein use the example of an EPS system, but the solution is also applicable to other settings, such as power tools, rotopumps and industrial applications, and other situations where PMDC motors are used.

Referring now to the drawings, the technical solutions will be described with reference to specific embodiments, but not limited thereto. FIG. 1 is an exemplary embodiment of a vehicle 10 including a steering system 12. In various embodiments, the steering system 12 includes a steering wheel 14 coupled to a steering shaft system 16, the steering shaft system 16 including a steering column, an intermediate shaft, and necessary joints. In one exemplary embodiment, the steering system 12 is an EPS system that further includes a steering assist unit 18, the steering assist unit 18 being coupled to the steering shaft system 16 of the steering system 12 and to the connecting rods 20, 22 of the vehicle 10. Alternatively, the steering assist unit 18 may couple an upper portion of the steering shaft system 16 with a lower portion of the system. The steering assist unit 18 includes, for example, a rack and pinion steering mechanism (not shown) that may be coupled to a steering actuator motor 19 and a gear arrangement through the steering shaft system 16. During operation, as the vehicle operator turns the steering wheel 14, the steering actuation motor 19 provides assistance to move the connecting rods 20, 22, which in turn move the steering knuckles 24, 26, respectively, that are each coupled to the wheels 28, 30 of the vehicle 10.

As shown in FIG. 1, the vehicle 10 also includes various sensors 31, 32, 33, which sensors 31, 32, 33 detect and measure observable conditions of the steering system 12 and/or the vehicle 10. The sensors 31, 32, 33 generate sensor signals based on the observable conditions. In one example, the sensor 31 is a torque sensor and is used to sense an input driver steering wheel torque (HWT) applied to the steering wheel 14 by the driver of the vehicle 10. The torque sensor generates a driver torque signal based thereon. In another example, the sensor 32 is a motor angle and speed sensor and is used to sense the rotational angle and rotational speed of the steering actuation motor 19. In yet another example, the sensor 33 is a steering wheel position sensor and is used to sense the position of the steering wheel 14. The sensor 33 generates a steering wheel position signal based thereon.

The control module 40 receives one or more sensor signals input from the sensors 31, 32, 33, and may receive other inputs, such as a vehicle speed signal 34. Based on the one or more inputs and further based on the steering control systems and methods of the present disclosure, the control module 40 generates command signals to control the steering actuation motor 19 of the steering system 12. The steering control system and method of the present disclosure applies signal conditioning via the steering assist unit 18 to control various aspects of the steering system 12. Communication with other subcomponents of the vehicle 10, such as an anti-lock braking system (ABS)44, an Electronic Stability Control (ESC) system 46, and other systems (not shown), may be performed using, for example, a Controller Area Network (CAN) bus or other vehicle networks known in the art to exchange signals such as the vehicle speed signal 34.

In one or more examples, the motor 19 is a PMDC motor, which is controlled using the techniques described herein.

FIG. 2 depicts a configuration of a PMDC machine in accordance with one or more embodiments. In the illustration, a first view 101 and a second view 102 of the construction of a PMDC machine are depicted. As shown, the PMDC machine 100 includes one pole pair (N and S)110, one brush pair (B1 and B2)120, six rotor slots (gaps between rotor poles T1-T6)130 and six commutator segments (1.1-1.2, 2.1-2.2 and 3.1-3.2)140 corresponding to each other, with a single-lap winding 150. Fig. 2 also includes a view of the equivalent circuit 105 of the machine. It should be noted that the solution described herein is not limited to the PMDC machine 100 having the configuration shown in fig. 2. Rather, in other examples, the PMDC machine 100 may include additional brush pairs 120, pole pairs 110. Alternatively or additionally, in other examples, the PMDC machine 100 may include a different number of rotor slots 130, or commutator segments 140 with different winding patterns.

FIG. 3 depicts another configuration of a PMDC machine in accordance with one or more embodiments. In the illustration, the construction of a PMDC machine is depicted using a first view 201 and a second view 202. The PMDC machine 100 includes two pole pairs 110, two brush pairs (B1-B2 and B3-B4)120, six rotor slots (gaps between rotor poles T1-T6)130, and corresponding 12 commutator segments (1.1-1.4, 2.1-2.4, and 3.1-3.4) 140. The windings 150 in the PMDC machine 100 use lap windings.

In both fig. 2 and 3, the PMDC machine 100 does not operate satisfactorily when the brushes fail because the terminals of the PMDC machine 100 bind the brushes 120 together. The solution described herein addresses this technical challenge by providing redundancy within PMDC machine 100 by adding multiple winding sets and additional brush pairs 120 within rotor slot 130 and terminals individually tapped from each brush pair 120. For example, a redundant solution may use 2 independent motor drivers (i.e., 2 motors, 2 inverters, and 2 microcontrollers). The use of such multiple subsystems results in additional cost and further requires additional packaging and housing of the components. The solution described herein uses a single motor in different ways, for example: (1) controlling a plurality of windings having a plurality of pairs of brushes in the motor by a microcontroller and a plurality of inverters, (2) controlling a plurality of windings having a plurality of pairs of brushes by a plurality of controllers and a plurality of inverters.

The solution described herein facilitates the inclusion of multiple PMDC machines within the same physical stator and rotor structure of a single PMDC machine. This disclosure refers to such PMDC machines including a plurality of PMDC machines as "multi-winding PMDC machines". Further, the solution includes a control architecture for a multi-winding machine with redundant power converters and logic circuits.

The mathematical model of a single-wound PMDC machine, such as PMDC machine 100 (fig. 2/3), is represented as follows:

T_e＝K_eI

v, I and T, among others_eIs the terminal voltage, current and electromagnetic torque of the machine, L, R, K_eAnd V_bdInductance, resistance, voltage (torque) constant, and brush drop. Note that the brush drop term is non-linear and can be expressed as follows.

Wherein, V₀And I₀Is a function of brush voltage dropAnd (4) variable quantity. Machine parameters vary non-linearly with operating conditions due to changes in temperature and magnetic saturation.

In a multi-winding PMDC machine, there is additional magnetic (inductive) coupling between the phases. Due to this coupling, the machine model is different from the single-wire wound machine described above.

Fig. 4 depicts an example multi-winding PMDC machine in accordance with one or more embodiments. The multi-winding PMDC machine 300 of fig. 4 is a "two-wire wound PMDC machine" having 4 stator poles (i.e., 2 pole pairs) 110, 12 commutation plates 130 and rotor slots, and 4 brushes (2 brush pairs B1-B4) 120. Further, the dual winding PMDC machine 300 includes distributed lap windings 150 having a full pitch (dimensional pitch).

FIG. 5 depicts a block diagram of a dual winding PMDC machine using a mathematical model in accordance with one or more embodiments. The view of the dual winding PMDC machine 300 depicts the controller 510 and the PMDC motor 520, in which case the motor 520 includes dual windings. In one or more examples, controller 510 operates in a feedback control mode. For a dual winding PMDC motor 520, two input voltages (V)₁)530a and (V)₂)530b may be based on voltage commands generated by controller 510 (e.g., by a power controller (not shown)). It should be noted that although ideally the voltage command generated by controller 510 is equal to the input voltage (V) of PMDC motor 520₁)530a and (V)₂)530b, in practice, these values may be slightly different due to, for example, non-linearity of the power converter circuit.

In addition, due to the back electromotive force (ω) of each corresponding winding_m) The voltage command is modified. The back emf is based on the speed of motor 520. For example, a first back electromotive force voltage (ω) of a first winding set of motor 520_m)532a is based on the motor speed and a first back emf (and torque) constant K for the first set of windings_e1. Similarly, a second back-emf voltage (ω) of a second set of windings of motor 520_m)532b based on motor speed and a second back emf (and torque) constant K for the second winding_e2。

Voltage drop (V) due to brushes of each winding_bd) To further repairThe voltage commands 530a-530b are changed. For example, a first voltage (V1)530a is added to the first winding's brush drop voltage, and a second voltage V₂And the voltage of the brush drop of the second winding. Converting the voltage to a current (I) for each winding based on the inductance and resistance of each winding₁)540a and (I)₂)540b, and the current further generates a resultant torque (T) from the motor 520_e)550. Based on a respective constant K for each winding_e1And K_e2Output torque 550 and current I₁And I₂And (4) in proportion. Furthermore, the magnetic coupling (M) between the two windings further influences the current generated by the voltage command.

Due to the additional magnetic coupling between the phases of the dual winding PMDC machine 300, the machine model of the machine 300 is different from the machine model of the single wound PMDC machine 100 compared to the single wound PMDC machine 200. For example, a mathematical model for the two-wire wound PMDC machine 300 is given below.

T_e＝K_e1I₁+K_e2I₂

Wherein M is₁₂＝M₂₁And M denotes inductive coupling between two phases. Generally, the mutual inductance term (M)₁₂I₂And M₂₁I₁) Random machine current I₁And I₂A non-linear change.

The model can be easily extended to n-phase PMDC machines, where n represents the number of windings used (or the number of redundant machines included in a single PMDC machine). A general model of an n-phase motor can be expressed as follows.

T_e＝K_e1I₁+K_e2I₂+…+K_enI_n

Where, in general, mutual inductance is specified to be different. Note that the mutual inductance of the two sets of windings (e.g., set a and set b) is equal, i.e., M_ab＝M_ba. For simplicity, the remaining description is directed to a double winding machine, which can be extended to a general n-phase machine. The voltage-current equation of a two-wire wound machine can be expressed in the form of a transfer matrix (transfer matrix) as follows.

Therein, it is assumed that the two brush-drop terms are independent of current in order to generate a transfer matrix representation of the PMDC machine (since a frequency domain representation of the transfer matrix requires a linear time-invariant model in the time domain). Therefore, the output current can be expressed as follows according to the input voltage.

Wherein Δ(s) ═ L₁s+R₁)(L₂s+R₂)-s²M²＝(L₁L₂-M²)s²+(L₁R₂+L₂R₁)s+R₁R₂。

When the winding arrangement is symmetric and the two brush pairs are similar, the model described above can be simplified to assume that the half-machines are identical, i.e., the self-inductance, resistance, voltage constant, and brush-drop parameters are equal.

Thus, in the dual winding PMDC machine 300, the controller 510 generates the output torque 550 using both windings simultaneously by generating voltage commands to generate the voltages 530a-530b such that the resulting currents result in the output torque 550. Controller 510 generates voltage commands 530a-530b based on output torque 550 to be generated by motor 520. In the event of a failure of one winding (e.g., the first winding), the corresponding current 540b continues to be generated using the second voltage command 530b on the second winding, resulting in at least a partial output torque 550.

Alternatively or additionally, the controller 510 generates only a single voltage command to produce the input voltage (e.g., the first voltage 530a) to generate the output torque using only the first winding. In the event of a failure of the first winding, the controller 510 then uses the second winding to generate a second input voltage (V)₂)530b, thereby generating output torque 550.

The above model can be extended to n-winding PMDC machines (rather than just dual windings) where the controller 510 uses n (n is greater than 2) voltage commands V for n windings₁-V_nEach voltage command generating a corresponding current I₁-I_nAnd they together cause the motor to generate an output torque (T)_e)550。

Fig. 6 depicts an example multi-winding PMDC machine in accordance with one or more embodiments. The multi-winding PMDC machine 600 of fig. 6 includes four PMDC machines with four pole pairs (stators), four brush pairs (B1-B8)120, 40 commutator segments (1.1-1.4-10.1-10.4) and 10 rotor slots (gaps between rotor poles T1-T10)130 for placing windings 150. Thus, the multi-winding PMDC machine 600 includes multiple (four) windings with multiple brush pairs and terminals, and thus, the PMDC machine 600 effectively includes multiple PMDC machines in the same stator and rotor physical structure. Thus, in the event of a single brush failure, the PMDC machine 300 continues to operate with the remaining (normal) terminals. In the illustrated example, four sets of terminals facilitate fault-tolerant operation in the event of brush failure.

To make the multi-winding PMDC machine 600 fault tolerant by providing redundancy, the multi-winding PMDC machine 600 includes greater than or equal to the number of brush pairs 120 of pole pairs 110 in the stator, and the number of pole pairs 110 is an integer multiple of the number of brush pairs 120. Further, the number of rotor slots 130 for the windings 150 is based on the number of brush pairs 120. Further, in different examples of the multi-winding PMDC machine 600, different winding arrangements may be selected for different purposes. For example, for a two-winding PMDC machine 300 (which is a multi-winding PMDC machine type with two windings), the conductors of the two half-machines may be within one half of the rotor, or the conductors may be placed in alternating slots in the outer periphery of the rotor. It should also be noted that the number of redundant machines in a multi-winding PMDC machine is chosen based on the application under consideration (including taking into account the geometry of the machine) to ensure the mechanical strength of the machine. It should be noted that the above is a general set of rules for implementing one or more embodiments described herein. The solution described herein facilitates the construction of n winding set PMDC machines (as well as n power converters and n microcontrollers) and there are various ways to construct such PMDC machines using the technical features described herein.

The multi-winding PMDC machine 600 facilitates the electric drive continuing to provide total power in the event of a failure of a pair of brushes (one winding set)This improves the fault tolerance of the drive system, thereby providing the ability to operate fail-safe.

Furthermore, in addition to using multi-winding PMDC machines, the solutions described herein facilitate additional redundancy by using a control architecture that includes multiple power converters (H-bridges) and/or microcontrollers.

Fig. 7 depicts an example system 700 using a multi-winding PMDC machine in accordance with one or more embodiments. The system 700 includes a multi-winding PMDC machine 600, the multi-winding PMDC machine 600 including n windings (n > -2). The system 700 also includes a controller 710, the controller 710 controlling the operation of the plurality of power converters 720. The power converter 720 includes one power converter for each winding in the multi-winding PMDC machine 600. For example, the first power converter 722 is associated with a first winding of the PMDC machine 600; a second power converter 724 is associated with the second winding of the PMDC machine 600, and so on, and an nth power converter 726 is associated with the nth winding of the PMDC machine 600.

The power converter 720 facilitates varying the voltage or frequency of the electrical energy provided to the PMDC machine 600. The power converter shown includes a physical switch (e.g., a MOSFET) and additional electronic circuitry, such as a gate driver that provides a voltage to a control input port of the switch of the power converter. For example, the control input port of a MOSFET type switch is the gate input terminal. The gate drive output voltage is the result of command signals sent by the controller 700 to control the current and torque of the PMDC machine.

In the event of a failure of one of the power converters 720 (e.g., the first converter 722), the controller 710 continues to operate the remaining normal power converters (724-726). The respective windings of the PMDC machine 600 provide a torque output that is obtained for the total torque generated with all windings (and converters) runningIn other words, the controller 710 bypasses the failed first converter 722 and the corresponding first winding and continues to operate the multi-winding PMDC machine 600 with n-1 windings, rather than completely de-operating the PMDC machine 600.

In addition to using a multi-wire wound PMDC machine and multiple power converters (H-bridges), the solution herein facilitates an additional level of redundancy by using multiple microcontrollers, each corresponding to multiple windings in the multi-PMDC machine 600.

FIG. 8 depicts an example fault tolerant system in accordance with one or more embodiments. The fault tolerant system 700 of fig. 8 has n-level redundancy (n > -2) that is more robust against machine faults, power converter faults, and controller faults, where n is the number of windings, the number of power converters, and the number of corresponding controllers in a PMDC machine. The fault tolerant system 700 of fig. 8 includes a multi-winding PMDC machine 600 having n winding sets, and also includes a plurality of power converters 720 corresponding to each winding set. In addition, the system 700 includes a controller 710, the controller 710 including a plurality of controllers 812 and 816, wherein each controller corresponds to one of the plurality of power converters 720. For example, the first controller 812 is associated with the first power converter 722, which is further associated with the first winding of the PMDC machine 600. Similarly, the second controller 814 is associated with a second power converter 724, further associated with a second winding of the PMDC machine 600, and so on, until the nth controller 816 is associated with an nth power converter 726, further associated with an nth winding set of the PMDC machine 600.

Each controller 710 operates independently of the other. Thus, in the event of a failure of first controller 812, system 700 continues to generate at least a portion of output torque 550 from PMDC machine 600 using the remaining (normal) controllers 814 and 816 of controller 710. Further, in the event of a failure of the first power converter 722, the system 700 continues to generate at least a portion of the output torque 550 from the PMDC machine 600 using the remaining (normal) power converters 724 and 726. Furthermore, in the event of a failure of the first winding of the PMDC machine 600, the system 700 continues to generate at least a portion of the output torque 550 from the PMDC machine 600 using the remaining (normal) windings of the PMDC machine 600.

Fig. 9 illustrates a flow diagram of an example method for providing fault tolerance in a PMDC motor control system using a multi-winding PMDC motor in accordance with one or more embodiments. The method comprises the following steps: the current controller 510 of the multi-winding PMDC motor 600 receives an amount of output torque 550 to be generated using the multi-winding PMDC motor drive system, as shown at 910. For example, the amount of output torque received may be a desired output torque for application (e.g., assistance torque provided by the steering system 12). Alternatively or additionally, the desired torque may be an amount of torque to be generated for controlling the steering system 12, an amount of output torque received from an autonomous driving assistance unit (not shown) of the vehicle 10 with a fully autonomous driving experience.

The method further comprises the following steps: bypassing one winding set associated with the failed microcontroller in the current controller 510 generates voltage commands for the other winding sets of the multi-winding motor, as shown at 920. For example, current controller 510 includes a plurality of microcontrollers, each microcontroller associated with a respective winding set of multi-winding PMDC motor 600. Each microcontroller generates a voltage command for a respective winding set based on predetermined parameters (e.g., back-emf factor, torque factor, etc.) associated with the winding set. In one or more examples, the parameters are symmetric among the plurality of winding sets, each microcontroller generating a symmetric voltage command. Alternatively, the winding sets do not have similar parameter values, and each microcontroller generates a different voltage command. In the event of a microcontroller failure, only the remaining normal microcontrollers generate the corresponding voltage commands.

The method further comprises the following steps: the voltage commands are sent to the respective winding sets with the operating power converter, as shown at 930. For example, each set of windings is associated with a respective power converter. In the event of a power converter failure, the corresponding winding set does not receive the corresponding voltage command.

The method further comprises the following steps: bypassing one winding set associated with the failed brush, and sending voltage commands to the other winding sets of the multi-winding motor, as shown at 940. The voltage command is sent using a pair of terminals of the winding that lead from a pair of brushes of the winding. For example, if a brush pair fails (e.g., a mechanical failure), the winding set does not receive a voltage command. Thus, only the normal set of windings associated with a normal power converter and a normal microcontroller receive a voltage command.

The method further includes generating an output torque based on the voltage command received by the normal winding set, as shown at block 950. If all of the winding sets are normal, the output torque generated matches the amount of output torque received, otherwise the output torque is at least a portion of the desired amount of output torque. Thus, the system provides fault tolerance capability, since without a PMDC motor including multiple windings, the motor will not generate any torque at all. Such a complete loss of torque may be undesirable in safety critical applications such as steering systems, automatic driving assistance systems.

FIG. 10 depicts an example fault tolerant system architecture in accordance with one or more embodiments. The fault tolerant system 700 of fig. 10 illustrates a multi-layered redundancy architecture that is robust to machine failures, power converter failures, and controller failures. As described herein, a PMDC machine 600 having n (n is the number of windings in the PMDC machine, n > ═ 2) levels of redundancy provides n levels of redundancy for machine winding faults. Further, architecture 700 provides an additional layer of redundancy and robustness through the use of multiple power converters 720 per winding set. For example, each winding set of the PMDC machine 600 is associated with a group of power converters, each group of power converters having k power converters, k ≧ 1. In this configuration, if a first power converter from the group of k power converters fails, one or more of the remaining k-1 power converters take over the failed power converter to operate, thereby providing redundancy and robustness to the failure of the power converters. In one or more examples, k may be 2.

It should be noted that in typical "normal" operation, a number of power converters in total k may be operating, and when a single power converter fails, the remaining k-1 power converters may share the burden in any combination. For example, under normal operation, k-2 converters may be operating, and when one of the operating converters fails, any k-2 converters may begin to operate to keep the system operating as before.

As depicted in the embodiment of the architecture in block 1010, a single controller 710 is associated with all N winding sets of PMDC machine 600. Thus, each of the k power converters in the N sets of power converters is controlled by a single controller 710.

Further, in one or more examples, architecture 700 provides an additional layer of redundancy and robustness through the use of multiple controllers 710. For example, each set of windings of PMDC machine 600 is associated with a respective group of controllers 812, 814, 816. Each group of controllers may have q controllers, q ≧ 1. In this configuration, if a first controller from the group of q controllers fails, one or more of the remaining q-1 controllers take over the operation of the failed controller, thereby providing redundancy and robustness to the failure of the controller. In one or more examples, q may be 2. As shown in the embodiment of the architecture in block 1020, a group of q controllers 812(814 and 816) is associated with each respective winding set of the PMDC machine 600.

It should be noted that in typical "normal" operation, multiple controllers in total q may be operating, and when a single controller fails, the remaining q-1 controllers may share the burden in any combination. For example, under normal operation, q-2 controllers may be running, and when one of the running controllers fails, any q-2 controllers may begin to run to keep the system running as before.

The use of multiple (k) power converters per winding set and multiple (q) controllers per winding set, with multiple (N) winding sets, contributes to the multi-tier configurable redundancy and robustness of the fault tolerant system 700.

The solution described herein facilitates various fault tolerant systems using multi-winding PMDC machines. In addition, these solutions also help fault tolerant systems with n-level redundancy, are more robust to machine and power converter failures (single controller), and are more robust to controller failures (multiple controllers). The PMDC-based electric drive system architecture described herein facilitates multiple levels of redundancy in the motor, power converter, and logic circuits (controllers). Thus, the drive architecture helps to improve fault tolerance and fail-safe operation in safety critical systems such as steering systems, automated driving assistance systems, etc.

The present technical solution may be a system, method and/or computer program product with any possible degree of technical detail integration. The computer program product may include a computer-readable storage medium (or media) having computer-readable program instructions embodied thereon for causing a processor to perform various aspects of the subject technology.

Aspects of the present technology are described herein with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems) and computer program products according to embodiments of the technology. It will be understood that each block of the flowchart illustrations and/or block diagrams, and combinations of blocks in the flowchart illustrations and/or block diagrams, can be implemented by computer-readable program instructions.

The flowchart and block diagrams in the figures illustrate the architecture, functionality, and operation of possible implementations of systems, methods and computer program products according to various embodiments of the present technology. In this regard, each block in the flowchart or block diagrams may represent a module, segment, or portion of instructions, which comprises one or more executable instructions for implementing the specified logical function(s). In some alternative implementations, the functions noted in the block may occur out of the order noted in the figures. For example, two blocks shown in succession may, in fact, be executed substantially concurrently, or the blocks may sometimes be executed in the reverse order, depending upon the functionality involved. It will also be noted that each block of the block diagrams and/or flowchart illustration, and combinations of blocks in the block diagrams and/or flowchart illustration, can be implemented by special purpose hardware-based systems which perform the specified functions or acts, or combinations of special purpose hardware and computer instructions.

It should also be appreciated that any module, unit, component, server, computer, terminal, or device executing instructions exemplified herein may include or otherwise have access to a computer-readable medium, such as a storage medium, computer storage medium, or data storage device (removable and/or non-removable) such as, for example, a magnetic disk, optical disk, or tape. Computer storage media may include volatile and nonvolatile, removable and non-removable media implemented in any method or technology for storage of information, such as computer readable instructions, data structures, program modules or other data. Such computer storage media may be part of, accessible by, or connected to the device. Any application or module described herein may be implemented using computer-readable/executable instructions that may be stored or otherwise accommodated by such computer-readable media.

While the subject matter has been described in detail in connection with only a limited number of embodiments, it should be readily understood that the subject matter is not limited to such disclosed embodiments. Rather, the technical solution can be modified to incorporate any number of variations, alterations, substitutions or equivalent arrangements not heretofore described, but which are commensurate with the spirit and scope of the technical solution. Additionally, while various embodiments of the technology have been described, it is to be understood that aspects of the technology may include only some of the described embodiments. Accordingly, the technical solutions should not be considered as being limited by the foregoing description.