CN111448750B - Fault tolerant permanent magnet DC motor driver - Google Patents

Abstract

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 set of windings of the PMDC motor, the second set of windings 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.

Description

Fault Tolerant Permanent Magnet DC Motor Drive

Background technique

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

The need for fault-tolerant operation of safety-critical systems such as those involved in automotive subsystems including electric power steering (EPS) and automated driver assistance systems (ADAS) is increasing. This need triggered the introduction of redundancy in electromechanical motion control systems, enabling improved fault tolerance and thus fail-safe operation. Electric drive systems typically include electric motors, one or more power converters and sensors, and other components used to facilitate the operation of the motion control system.

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

Contents of the invention

According to 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 magnetic poles, a first pair of brushes and a first winding. Additionally, a second winding set of the plurality of winding sets includes a second pair of magnetic 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 set of windings, wherein the first set of windings generates a first current in response to the first voltage command, And the controller causes the PMDC motor to generate a predetermined amount of torque by applying a second voltage command to a second set of windings, wherein the second set of windings 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.

According to one or more embodiments, a permanent magnet direct current (PMDC) motor includes multiple winding sets. A first winding set of the plurality of winding sets includes a first pair of magnetic 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 magnetic poles, a second pair of brushes, and a second winding. The first set of windings generates a first current command in response to a first voltage command from the controller. The second set of windings generates a second current command in response to a second voltage command from the controller.

According to one or more embodiments, a method for generating output torque of a multi-winding PMDC motor includes generating, by a current controller, a first voltage command for a first winding set of a plurality of winding sets of the PMDC motor, wherein , the first set of windings generates a first current in response to a first voltage command. The method also includes generating, by the current controller, a second voltage command for a second set of windings of the plurality of winding sets of the PMDC motor, wherein the second set of windings 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.

Description of the drawings

The subject matter of 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 present disclosure will become apparent from the following detailed description taken in conjunction with the accompanying drawings, in which:

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

Figure 2 depicts the construction of a PMDC machine in accordance with one or more embodiments;

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

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

Figure 5 depicts a block diagram of a two-winding PMDC machine using a mathematical model in accordance with one or more embodiments;

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

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

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

9 illustrates a flowchart 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.

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

Detailed ways

The terms "module" and "sub-module" are used herein to refer to one or more processing circuits (e.g., application specific integrated circuits (ASICs), electronic circuits), processors (shared, dedicated or grouped) and memory, combinational logic circuitry, and/or other suitable components that provide the described functionality. It is understood that the sub-modules described below can be combined and/or further divided.

Permanent magnet DC (PMDC) motors are widely used in automotive applications such as electric power steering (EPS) systems. PMDC motor has three main components, namely stator, rotor and commutator. Typically, the stator contains the magnetic poles, while the rotor is the armature carrying the windings. The commutator is attached to the brushes and slip rings to allow mechanical commutation of the machine. Here, the machine can be a PMDC motor itself, or a system using a PMDC motor, such as an EPS system. The brushes are connected to the phase terminals through which voltage is applied to the machine. Electric brushes are often susceptible to mechanical wear. Mechanical wear and tear can cause the PMDC motor to malfunction, after which the machine will become inoperable. In an EPS system setup, not using the PMDC motor results in a loss of driver assistance. In addition to the electric motor, the power converter circuitry and the microcontroller (logic) board used to control the electric drive system are also susceptible to failure.

The technical solution described in this article addresses the above technical challenges by promoting fault tolerance in PMDC-based electric drive systems by including techniques for introducing redundancy in PMDC machines and control architectures involving redundancy in power converters and logic circuits. . In addition, the technical solution also provides an analytical model of the PMDC machine. It should be noted that the various implementations of the technology described herein use the example of an EPS system, however, the technology is also applicable to other settings such as power tools, rotary pumps and industrial applications, as well as other situations where PMDC motors are used.

Referring now to the accompanying drawings, technical solutions will be described with reference to specific embodiments, but are 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 that includes a steering column, a countershaft, and necessary joints. In one exemplary embodiment, steering system 12 is an EPS system that also includes a steering assist unit 18 coupled to steering shaft system 16 of steering system 12 and to connecting rod 20 of vehicle 10 ,twenty two. Alternatively, the steering assist unit 18 may couple the upper part of the steering shaft system 16 with the lower part of this system. The steering assist unit 18 includes, for example, a rack and pinion steering mechanism (not shown) which may be coupled to the steering actuation motor 19 and gearing via a steering shaft system 16 . During operation, as the vehicle operator turns the steering wheel 14 , the steering actuator motor 19 provides assistance in moving the connecting rods 20 , 22 , which in turn are coupled to the wheels 28 , 30 of the vehicle 10 . The steering knuckles 24, 26 move.

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

Control module 40 receives one or more sensor signals as input from sensors 31 , 32 , 33 and may receive other inputs such as 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 systems and methods of the present disclosure apply signal conditioning through the steering assist unit 18 to control various aspects of the steering system 12 . Interaction with other subcomponents of the vehicle 10 (e.g., anti-lock braking system (ABS) 44 , electronic stability control (ESC) system) may be performed using, for example, a controller area network (CAN) bus or other vehicle networks known in the art. 46 and other systems (not shown)) to exchange signals such as the vehicle speed signal 34 .

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

Figure 2 depicts the construction 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 in the figure, the PMDC machine 100 includes a magnetic pole pair (N and S) 110, a brush pair (B1 and B2) 120, six rotor slots (gaps T1-T6 between rotor poles) 130 corresponding to each other, and Six commutator segments (1.1-1.2, 2.1-2.2 and 3.1-3.2) 140 with a single stack of windings 150. Figure 2 also includes a view of the equivalent circuit 105 of the machine. It should be noted that the technical solution described herein is not limited to the PMDC machine 100 having the configuration shown in FIG. 2 . Conversely, in other examples, 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.

Figure 3 depicts another configuration of a PMDC machine in accordance with one or more embodiments. In the illustration, the construction of the 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 Figures 2 and 3, the PMDC machine 100 does not operate satisfactorily when a brush fails because the terminals of the PMDC machine 100 cause the brushes 120 to tie together. The technical solution described herein solves this problem by providing redundancy within the PMDC machine 100 by adding multiple winding sets and additional brush pairs 120 within the rotor slots 130 and individually derived terminals from each brush pair 120 This technical challenge. For example, a redundant solution could use 2 independent motor drives (i.e. 2 motors, 2 inverters and 2 microcontrollers). However, the use of such multiple subsystems results in additional costs and further requires additional packaging and housing of the components. The technical solution described in this article uses a single motor in different ways, such as: (1) through a microcontroller and multiple inverters to control multiple windings with multiple pairs of brushes in the motor, (2) through multiple controllers and multiple inverters control multiple windings with multiple pairs of brushes.

The technical solutions described herein facilitate 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 that include multiple PMDC machines as "multi-winding PMDC machines." Furthermore, the technical solution includes a control architecture for multi-winding machines with redundant power converters and logic circuits.

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

T _e =K _e I

Among them, V, I and _Te are the terminal voltage, current and electromagnetic torque of the machine, L, R, _Ke and V _bd are the inductance, resistance, voltage (torque) constant and brush voltage drop. Note that the brush voltage drop term is non-linear and can be expressed as follows.

Among them, V ₀ and I ₀ are the state variables of the brush voltage drop function. Machine parameters vary non-linearly with operating conditions due to changes in temperature and magnetic saturation.

In multi-winding PMDC machines, there is additional magnetic (inductive) coupling between the phases. Because of this coupling, the machine model differs from the single wire wound machine described above.

Figure 4 depicts an example multi-winding PMDC machine in accordance with one or more embodiments. The multi-winding PMDC machine 300 of Figure 4 is a "bifilar PMDC machine" having 4 stator poles (i.e. 2 pole pairs) 110, 12 commutating plates 130 and rotor slots, and 4 brushes ( 2 brush pairs B1-B4)120. Furthermore, the dual-winding PMDC machine 300 includes distributed stack windings 150 with diametrical pitch.

Figure 5 depicts a block diagram of a two-winding PMDC machine using a mathematical model in accordance with one or more embodiments. The view of a dual winding PMDC machine 300 depicts a controller 510 and a PMDC motor 520, in this case the motor 520 includes dual windings. In one or more examples, controller 510 operates in a feedback control mode. For the dual-winding PMDC motor 520, the two input voltages (V ₁ ) 530a and (V ₂ ) 530b may be based on voltage commands generated by the controller 510 (eg, through a power controller (not shown)). It should be noted that although ideally the voltage commands generated by the controller 510 are equal to the input voltages (V ₁ ) 530 a and (V ₂ ) 530 b of the PMDC motor 520, in practice, these Values may vary slightly.

Furthermore, the voltage command is modified due to the back electromotive force (ω _m ) of each respective winding. The back electromotive force is based on the speed of the motor 520. For example, the first back EMF voltage (ω _m ) 532a of the first set of windings of the motor 520 is based on the motor speed and the first back EMF (and torque) constant _Ke1 of the first set of windings. Similarly, the second back EMF voltage (ω _m ) 532b of the second set of windings of the motor 520 is based on the motor speed and the second back EMF (and torque) constant _Ke2 of the second winding.

The voltage commands 530a-530b are further modified due to the brush drop voltage ( _Vbd ) of each winding. For example, the first voltage (V1) 530a is added to the brush drop voltage of the first winding, and the second voltage _V2 is added to the brush drop voltage of the second winding. This voltage is converted into currents (I ₁ ) 540a and (I ₂ ) 540b for each winding based on the inductance and resistance of each winding, and the currents further generate resultant torque (T _e ) 550 from the motor 520 . The output torque 550 is proportional to the currents I ₁ and I ₂ based on the corresponding constants _Ke1 and _Ke2 for each winding. In addition, the magnetic coupling (M) between the two windings further affects 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 differs from the machine model of the single-winding PMDC machine 100 compared to the single-winding PMDC machine 200. For example, a mathematical model for a bifilar PMDC machine 300 is given below.

T _e =K _e1 I ₁ +K _e2 I ₂

Among them, M ₁₂ =M ₂₁ =M represents the inductive coupling between the two phases. Typically, the mutual inductance terms (M ₁₂ I ₂ and M ₂₁ I ₁ ) vary nonlinearly with the machine currents I ₁ and I ₂ .

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). The general model of an n-phase motor can be expressed as follows.

T _e ＝K _e1 I ₁ +K _e2 I ₂ +…+K _en I _n

where, in general, the mutual inductances are specified as different. Please note that the mutual inductances of the two sets of windings (eg, group a and group b) are equal, that is, M _ab = M _ba . For simplicity, the remaining description is for a two-winding machine, which can be extended to a general n-phase machine. The voltage-current equation for a bifilar-wound machine can be expressed in transfer matrix form as follows.

Among them, the two brush voltage drop terms are assumed to be independent of the current in order to generate the transfer matrix representation of the PMDC machine (because the 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 based on the input voltage.

Among them, Δ(s)=(L ₁ s+R ₁ )(L ₂ s+R ₂ )-s ² M ² =(L ₁ L ₂ -M ² )s ² +(L ₁ R ₂ +L ₂ R ₁ )s+R ₁ R ₂ .

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

Therefore, in the dual-winding PMDC machine 300, the controller 510 generates output torque 550 using both windings simultaneously by generating voltage commands to generate voltages 530a-530b such that the resulting current results in 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 (eg, the first winding), a corresponding current 540b continues to be generated using the second voltage command 530b on the second winding, resulting in at least partial output torque 550.

Alternatively or additionally, controller 510 generates only a single voltage command to generate an input voltage (eg, first voltage 530a), thereby using only the first winding to generate output torque. In the event that the first winding fails, the controller 510 then uses the second winding to generate a second voltage command that produces 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 two-windings), where the controller 510 uses n (n greater than 2) voltage commands V ₁ -V _n for n windings, each voltage command generating a corresponding Currents I _{1 -In} , and together they cause the motor to generate output torque (T _e ) 550.

Figure 6 depicts an example multi-winding PMDC machine in accordance with one or more embodiments. The multi-winding PMDC machine 600 of Figure 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 T1-T10 between rotor poles) 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 within the same stator and rotor physical structure. Therefore, in the event of a single brush failure, the PMDC machine 300 continues to operate using the remaining (normal) terminals. In the example shown, four sets of terminals facilitate fault-tolerant operation in the event of brush failure.

In order to make the multi-winding PMDC machine 600 fault tolerant by providing redundancy, the multi-winding PMDC machine 600 includes a number of pole pairs 110 in the stator that is greater than or equal to the number of brush pairs 120 and the number of pole pairs 110 is the number of brush pairs 120 Integer multiple. Furthermore, the number of rotor slots 130 for windings 150 is based on the number of brush pairs 120 . Furthermore, in different examples of multi-winding PMDC machines 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 for the two halves of the machine may be within one half of the rotor, or the conductors may be placed in alternating slots around the 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 considered (including consideration of the machine geometry) 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 technical solution described herein facilitates the construction of a PMDC machine of n winding sets (as well as n power converters and n microcontrollers), and there are various ways of constructing such a PMDC machine using the technical features described herein.

The multi-winding PMDC machine 600 helps the electric drive continue to provide total power in the event of a brush pair (one winding set) failure. This increases the fault tolerance of the drive system, providing the ability for fail-safe operation.

Furthermore, in addition to using multi-winding PMDC machines, the technical solution described herein also facilitates additional redundancy through the use of a control architecture containing multiple power converters (H-bridges) and/or microcontrollers.

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

Power converter 720 helps change the voltage or frequency of electrical energy provided to PMDC machine 600 . The power converter shown includes a physical switch (eg, a MOSFET) and additional electronic circuitry, such as a gate driver that provides a voltage to the 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 in order to control the current and torque of the PMDC machine.

In the event that one of the power converters 720 (eg, the first converter 722) fails, 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 obtained that is a function of the total torque generated with all windings (and converters) operating. In 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 disabling the PMDC machine 600 entirely.

In addition to using a multi-wire wound PMDC machine and multiple power converters (H-bridges), the technical solution of this article also facilitates additional microcontrollers by using multiple microcontrollers corresponding to multiple windings in the multi-PMDC machine 600 Redundancy level.

Figure 8 depicts an example fault-tolerant system in accordance with one or more embodiments. The fault-tolerant system 700 of Figure 8 has n levels of redundancy (n>=2), which is more robust to machine failures, power converter failures, and controller failures, where n is the number of windings in the PMDC machine, power converter The number and corresponding number of controllers. The fault-tolerant system 700 of Figure 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. Additionally, system 700 includes a controller 710 that includes a plurality of controllers 812 - 816 , where 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 the second power converter 724 , which is further associated with the second winding of the PMDC machine 600 , and so on until the nth controller 816 is associated with the nth power converter 726 is further associated with the nth winding set of the PMDC machine 600.

Each controller 710 operates independently of the other. Therefore, in the event that the first controller 812 fails, the system 700 continues to generate at least a portion of the output torque 550 from the PMDC machine 600 using the remaining (normal) controllers 814 - 816 of the controller 710 . Furthermore, 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 724-726. 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.

9 illustrates a flowchart 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 includes the current controller 510 of the multi-winding PMDC motor 600 receiving an amount of output torque 550 to be generated using the multi-winding PMDC motor drive system, as shown at 910 . For example, the received amount of output torque may be a desired output torque for an application (eg, providing assist torque by the steering system 12 ). Alternatively or additionally, the desired torque may be the amount of torque to be generated for controlling the steering system 12 in the case of a fully automated driving experience, received from an automated driving assistance unit (not shown) of the vehicle 10 Output torque amount.

The method also includes bypassing one winding set associated with the failed microcontroller in current controller 510 and generating voltage commands for each of 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 set of windings of multi-winding PMDC motor 600 . Each microcontroller generates a voltage command for a respective winding set based on predetermined parameters associated with that winding set (eg, back electromotive force factor, torque factor, etc.). In one or more examples, the parameters are symmetrical across multiple winding sets and each microcontroller generates symmetrical voltage commands. Alternatively, each winding set does not have similar parameter values and each microcontroller generates a different voltage command. In case of microcontroller failure, only the remaining healthy microcontroller generates the corresponding voltage command.

The method also includes sending the voltage command to the corresponding winding set with the power converter operating, as shown at 930 . For example, each winding set is associated with a corresponding power converter. In the event of a power converter failure, the corresponding set of windings does not receive the corresponding voltage command.

The method also includes bypassing one winding set associated with the failed brush and sending voltage commands to other winding sets of the multi-winding motor, as shown at 940 . Voltage commands are sent using pairs of terminals of the winding leading from pairs of the winding's brushes. For example, if a brush pair fails (e.g., mechanical failure), that set of windings will not receive a voltage command. Therefore, only the normal set of windings associated with the normal power converter and the normal microcontroller receives voltage commands.

The method also includes generating output torque based on the voltage command received by the normal set of windings, as shown at block 950 . If all 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. Therefore, the system provides fault tolerance because without the inclusion of multiple windings in the PMDC motor, the motor would not generate any torque at all. This complete loss of torque may be undesirable in safety-critical applications such as steering systems, automated driving assistance systems.

Figure 10 depicts an example fault-tolerant system architecture in accordance with one or more embodiments. Fault-tolerant system 700 of Figure 10 illustrates a multi-layer redundant architecture that is robust to machine failures, power converter failures, and controller failures. As described herein, a PMDC machine 600 with n (n is the number of windings in the PMDC motor, n >= 2) levels of redundancy provides n levels of redundancy for machine winding failures. Additionally, the architecture 700 provides an additional layer of redundancy and robustness by using multiple power converters 720 per winding set. For example, each winding set of the PMDC machine 600 is associated with a set of power converters, each set having k power converters, k≥1. In this configuration, if a first power converter from a group of k power converters fails, one or more of the remaining k-1 power converters take over the operation of the failed power converter, thus giving Provides redundancy and robustness against power converter failures. In one or more examples, k may be 2.

It should be noted that in typical "normal" operation, multiple power converters in the total k may be operating, and when a single power converter fails, the remaining k-1 power converters can share the load in any combination . For example, under normal operation, k-2 converters may be running, and when one of the running converters fails, any k-2 converters can start running 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 the PMDC machine 600 . Therefore, each of the k power converters in the N groups of power converters is controlled by a single controller 710 .

Additionally, in one or more examples, architecture 700 provides additional layers of redundancy and robustness through the use of multiple controllers 710 . For example, each winding set of the PMDC machine 600 is associated with a corresponding set of controllers 812, 814, 816. Each group of controllers can have q controllers, q≥1. In this configuration, if the first controller from a group of q controllers fails, one or more of the remaining q-1 controllers take over the operation of the failed controller, thus providing a Redundancy and robustness. 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 the total number q may be running, and when a single controller fails, the remaining q-1 controllers can be used in any combination to share the load. For example, under normal operation, q-2 controllers may be running, and when one of the running controllers fails, any q-2 controllers can start running to keep the system running as before.

Fault-tolerant system 700 is facilitated to have multiple levels of configurability through multiple (N) winding sets, combined with the use of multiple (k) power converters per winding set and the use of multiple (q) controllers per winding set. Redundancy and robustness.

The technical solution described in this article facilitates various fault-tolerant systems using multi-winding PMDC machines. In addition, these technical solutions also help fault-tolerant systems with n-level redundancy, be more robust to machine and power converter failures (single controller), and be more robust to controller failures (multiple controllers). The PMDC-based electric drive system architecture described in this article promotes multiple levels of redundancy in the motor, power converter, and logic circuitry (controller). Drive architectures therefore contribute to improved fault tolerance and fail-safe operation in safety-critical systems such as steering systems, automated driving assistance systems, etc.

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

Aspects of the technical solutions 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 technical solutions. 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 flowcharts 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 includes one or more executable instructions for implementing the specified logical functions. In some alternative implementations, the functions noted in the blocks may occur out of the order depicted 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 on the functionality involved. It should also be noted that each block of the block diagrams and/or flowchart illustrations, and combinations of blocks in the block diagrams and/or flowchart illustrations, can be implemented by special purpose hardware-type systems that perform the specified function or act, or by combinations of special purpose hardware and computer instructions.

It should also be understood that any module, unit, component, server, computer, terminal or device executing instructions exemplified herein may include or otherwise access computer-readable media, such as storage media, computer storage media or data storage devices (removable and/or non-removable), such as magnetic disks, optical disks or tapes. 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, or connected to the device. Any applications or modules described herein may be implemented using computer-readable/executable instructions that may be stored or otherwise contained by such computer-readable media.

Although the technical solution has been described in detail in conjunction with only a limited number of embodiments, it should be easily understood that the technical solution is not limited to these disclosed embodiments. Rather, the technical solutions can be modified to incorporate any number of variations, changes, substitutions or equivalent arrangements not heretofore described, but which are commensurate with the spirit and scope of the technical solutions. Additionally, while various embodiments of the technical solutions have been described, it is to be understood that aspects of the technical solutions may include only some of the described embodiments. Therefore, the technical solution should not be regarded as limited by the foregoing description.

Claims (10)

1. A system, comprising:

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

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

a second winding set comprising a second pair of poles, a second pair of brushes, and a second winding, wherein the first winding and the second winding are symmetrically arranged, the first winding set having a first pair of terminals, the second winding set having a second pair of terminals, and wherein the first pair of terminals are drawn from the first pair of brushes, the second pair of terminals are drawn from the second pair of brushes, the first pair of terminals and the second pair of terminals being separately provided; and

a plurality of power converters, wherein each group of power converters corresponds to a respective winding set; 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 set of windings, the second set of windings generating a second current in response to the second voltage command; and

the first and second currents cause the motor to generate the predetermined amount of torque;

wherein when one power converter of a group of power converters fails, the remaining power converters of the group of power converters are operable in any combination to maintain the system operational.

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

3. The system of claim 1, wherein the controller comprises: a plurality of controllers, wherein each group of controllers corresponds to a winding set.

4. 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, continuing to generate the second voltage command for the second winding set.

5. A permanent magnet direct current, PMDC, motor comprising:

a plurality of winding sets, comprising:

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

a second winding set including a second pair of poles, a second pair of brushes, and a second winding; and a plurality of power converters, wherein each group of power converters corresponds to a respective winding set; wherein the first winding set generates a first current command in response to a first voltage command from a controller;

the second winding set generates a second current command in response to a second voltage command from the controller; and is also provided with

Wherein the first winding and the second winding are symmetrically arranged, the first winding set having a first pair of terminals and the second winding set having a second pair of terminals, and wherein the first pair of terminals is led from the first pair of brushes and the second pair of terminals is led from the second pair of brushes, the first pair of terminals and the second pair of terminals being provided separately;

wherein when one of the power converters of a group fails, the remaining power converters of the group are operable in any combination to maintain operation of the PMDC motor.

6. A PMDC motor according to claim 5 wherein the controller comprises a plurality of controllers, wherein each controller corresponds to one 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.

7. The PMDC motor according to claim 5, wherein the controller includes: a plurality of controllers, wherein each group of controllers corresponds to a winding set.

8. 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 a 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;

wherein the first winding set comprises a first winding, the second winding set comprises a second winding, and the first winding and the second winding are symmetrically arranged, the first winding set has a first pair of terminals, the second winding set has a second pair of terminals, and wherein the first pair of terminals are led out from a first pair of brushes, the second pair of terminals are led out from a second pair of brushes, and the first pair of terminals and the second pair of terminals are separately provided; and is also provided with

Wherein the PMDC motor is associated with a plurality of power converters, wherein each group of power converters corresponds to a respective winding set, and when one of the group of power converters fails, the remaining power converters of the group of power converters are operable in any combination to maintain operation of the PMDC motor.

9. The method of claim 8, wherein the current controller comprises a plurality of controllers, wherein each controller corresponds to one winding set, a first controller is used to generate the first voltage command for the first winding set, and a second controller is used to generate the second voltage command for the second winding set.

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