Three-level generic motor driver

Abstract

A driver for a brushless DC electric motor supplies direct voltage to each of two terminals of the individual stator coils to drive the motor. The driver comprises an input supply voltage which feeds the motor via three power terminals, a +vdc terminal, a middle point terminal, and a — vclc terminal. Each stator coil terminal of the motor is connected via switches to the power terminals and some of the terminals may be connected to those of other coils. The switches allow a state in which a respective terminal is left open. The driver includes a controller to operate the switches in accordance with a switching protocol to control the electric motor.

Description

[0001] THREE-LEVEL GENERIC MOTOR DRIVER

[0002] RELATED APPLICATION / S

[0003] This application claims the benefit of priority of U.S. Provisional Patent Application No. 63 / 523,662, filed on June 28, 2023, the contents of which are incorporated herein by reference in their entirety.

[0004] FIELD AND BACKGROUND OF THE INVENTION

[0005] The present invention, in some embodiments thereof, relates to a driver for an electric motor and, more particularly, but not exclusively, to a three-level generic motor driver.

[0006] Electronic drivers are important tools since they are used in electric motors in the domestic and work environments as well as transportation, and various industrial processes. The evolution of electric vehicles catalyzed the massive growth of electric motor drivers. Many types of electric motors are employed in electric vehicles, and such motors include inductance machines, permanent magnet synchronous machines, switched reluctance motors, and permanent brushless de motors. In most cases, the supply voltage source is direct current (de), while the three-phase motor requires an alternating current (ac) source; thus, a driver is necessary.

[0007] There are four basic types of power electronics converters. A rectifier (ac-dc), ac-ac, dc- dc, and inverter (dc-ac). The relevant converters for driving three-phase motors are the ac-ac when there is an ac Grid source or ac micro-grid, and inverters when there is a de source such as a battery. In ac-ac converters, the output terminal has an amplitude which is different from the input amplitude and may also be at a different frequency. When the driver varies the output frequency, the ac-ac converter contains a rectifier, de bus, and inverter. Besides the synchronous machine, all the other electric motor types require a variable frequency source. As mentioned earlier, the motors are characterized by three-phase coils governed mainly by a voltage or current source inverter that allows for control of the amplitude and frequency.

[0008] Different loads are characterized by their torque and speed, where the load power deviates or remains constant. In the transportation category, during the start of driving, the vehicle accelerates, the torque is stable, and the speed rises linearly. Then, in cruising, the torque falls as the angular velocity increases, resulting in constant power operation. During the breaking period, the speed decreases, and the torque is negative.

[0009] Reference is now made to Fig. 1, which is a simplified illustration of a closed-loop control system required to conserve the operating point at a determined value in a three-level T-type universal inverter. In most cases, the reference signal for the controller is the speed or the torque. Energy source 10 provides power to driver 12 which in turn provides pulse width modulated (pwm) signals to motor 14. The motor in turn drives load 16. However, the motor and the driving circuit elements must operate within allowed limits; therefore, a current limit control loop is commonly added in cascade to the control system. Controller 18 thus receives feedback from the motor, such as voltage, current, speed and torque. Input from throttle 20 sets a control point, and the control system’s main tasks are to improve efficiency, enable stable speed / torque / power control for transient and steady- state for operations in all four quadrants, and enhance optimal control strategies.

[0010] Several control methods apply to motor speed control. Techniques include scalar control, field-oriented control, direct torque control, space vector-based algorithms, fuzzy logic control, voltage-level-based algorithms, and neural network control. These control methods can be employed for many types of dc-ac converters. The three-phase voltage source inverter (VSI) is the most common driver, whereas a two-level de voltage source may provide a feed. In motor applications, the VSI coils utilize the motor inductors; thus, the driving circuit is minimized and requires only six switches, as presented in Figure 2, which shows a full bridge voltage source inverter. Specifically, Fig. 2 shows an energy source 22, which is connected via six switches Q1..Q6 to three motor windings, a-a’, b-b’ and c-c’. The paired switches, Q1-Q4, Q2- Q5 and Q3- Q6 cannot be set at the same time or that would cause a short circuit, and each winding input may be selectively connected to the positive or the negative power line. The winding outputs are all connected together at neutral node 24 and are not available to the control system.

[0011] The full bridge voltage source inverter is also named the six -block commutation, and significant downsides include a relatively high torque ripple and unwanted d-axis currents. Specific topologies include the multilevel VSI, the neutral point clamped, the flying capacitor, the cascaded h-bridge, and others, and their use may reduce the current ripple and total harmonic distortion (THD). The drawback is that switching count rises, and the control circuitry is more complex. The main modulation techniques are divided into the voltage level-based algorithm: the multicarrier PWM, hybrid modulation, selective harmony elimination, and nearest level control; a second modulation technique is the space vector-based algorithm, such as the space vector modulation and the space vector control.

[0012] SUMMARY OF THE INVENTION

[0013] The present embodiments relate to a de - ac type driver and to the use of full switching so that all motor coil terminals are fully switchable to be connected to their respective power terminals and to any of the other motor coil terminals. A switching algorithm then provides the desired type of control method to drive the motor. According to a first aspect of the present invention, there is provided an electric motor and driver, the electric motor having at least three coils, the driver having three driver terminals to supply three levels of direct voltage to said coils selectively to drive said motor; the motor coils each having first and second coil terminals respectively, respective first coil terminals being selectively connectable to all three of said driver terminals and respective second coil terminals being selectively connectible to two of said driver terminals or to others of said respective second coil terminals.

[0014] In an embodiment, said three driver terminals comprise a +vclcterminal, a middle point terminal, and a — vclcterminal.

[0015] In an embodiment, each coil terminal of said motor is connected via switches to respective ones of said driver terminals.

[0016] Embodiments may include a controller to operate said switches in accordance with a switching protocol to drive said electric motor.

[0017] In embodiments, said switching protocol comprises combinations wherein ones of said motor coils are connected to others of said motor coils.

[0018] In embodiments, said switching protocol includes combinations in which ones of said coil terminals are left open.

[0019] In embodiments, said three driver terminals comprise a +vclcterminal and wherein one of said switches is located to connect said +vdc driver terminal to a common node of said respective second coil terminals.

[0020] In embodiment, said switches are controllable to provide current paths between any combination of said plurality of motor coils.

[0021] In embodiments, said switches are controllable to provide 120 degree commutation.

[0022] In embodiments, said switches are controllable to provide 180 degree commutation.

[0023] In embodiments, said switches are controllable to provide pulse width modulation.

[0024] In embodiments, said switches are controllable to provide a space vector-based switching algorithm.

[0025] Embodiments may have three motor coils, and five switches per motor coil. Alternative embodiments may have three motor coils, five switches per motor coil and one additional switch.

[0026] Embodiments, may have more than three motor coils, and five switches per motor coil. An extra switch may be included to connect a common node of the coils to the positive power line, that is to say such an embodiment may comprise more than three motor coils, five switches per motor coil and one additional switch. According to a second aspect of the present invention there is provided a power source for the driver, the power source comprising a power train for an electric vehicle. The power train may include two units, or just a single unit, as preferred.

[0027] According to a third aspect of the present invention, there is provided an electric motor having at least three coils, each coil extending between first and second terminals respectively, and wherein each of said first and second terminals are available to an external control system.

[0028] A fourth aspect of the present invention lies in a control system to drive the above- mentioned motor. The control system may comprise a DC power source having a positive power line, a negative power line and a neutral power line, and switches for selective connection, wherein one switch respectively connects each first terminal to said positive power line, one switch respectively connects each first terminal to said negative power line, one switch respectively connects each said first terminal to said neutral power line, one switch connects a common node of each said second terminal to said positive power line, one switch respectively connects each said second terminal to said common node, and one switch respectively connects each said second terminal to said negative power line.

[0029] A fifth aspect of the present invention may comprise a method of driving an electric motor, the electric motor having at least three coils, each coil extending between first and second terminals respectively, and wherein each of said first and second terminals are available to an external control system, the method comprising connecting each of said first terminals to a positive power line of a DC power source, to a negative power line of said DC power source and to a neutral power line, and selectively connecting each of said second terminals to a common node or to said negative power line, and selectively connecting said common node to said positive power line, said selectively connecting being in accordance with a predetermined drive sequence.

[0030] A two-part power source may be used with the driver. Each part of the power source is separately managed, say by a battery management system, so that if one part fails, driving remains possible using the other part.

[0031] Unless otherwise defined, all technical and / or scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the invention pertains.

[0032] Although methods and materials similar or equivalent to those described herein can be used in the practice or testing of embodiments of the invention, exemplary methods and / or materials are described below. In case of conflict, the patent specification, including definitions, will control. In addition, the materials, methods, and examples are illustrative only and are not intended to be necessarily limiting. BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING(S)

[0033] Some embodiments of the invention are herein described, by way of example only, with reference to the accompanying drawings. With specific reference now to the drawings in detail, it is stressed that the particulars shown are by way of example and for purposes of illustrative discussion of embodiments of the invention. In this regard, the description taken with the drawings makes apparent to those skilled in the art how embodiments of the invention may be practiced.

[0034] In the drawings:

[0035] FIG. 1 is a prior art motor control loop;

[0036] FIG. 2 is a prior art full bridge voltage source inverter;

[0037] FIG. 3 is a simplified diagram showing a network topology for a three-coil motor according to an embodiment of the present invention;

[0038] FIGs. 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14 and 15 illustrate different switching paths through the terminals and motor coils of the topology of Fig. 3 to control the motor; and

[0039] FIG. 16 is a simplified diagram schematically showing the terminals and connections according to embodiments of the present invention.

[0040] DESCRIPTION OF SPECIFIC EMBODIMENTS OF THE INVENTION

[0041] The present invention, in some embodiments thereof, relates to a driver for an electric motor and, more particularly, but not exclusively, to a three-level generic motor driver.

[0042] Electronic motor driving is a key feature in the electric era. The standard approach for driving electric motors is based on the three-phase voltage source inverter. This topology is well- known and easy to use in many applications. The advances in electric vehicles and other motor applications require more versatile tools to support new features along with improvements in efficiency, torque ripple, and braking energy regeneration. A generic driver according to the present embodiments may supply thirteen voltage levels and fifteen current levels at continuous operation, without high-frequency modulation. The unique energy topology increases reliability and system robustness in the event of battery malfunction. The driver according to the present embodiments may operate with different types of motors using various control algorithms. The present disclosure introduces a driver for several basic operations; however, the present embodiments may also be easily utilized with alternative control algorithms, for example algorithms that apply high- frequency modulation, such as space vector algorithms.

[0043] The present embodiments provide a driver for an electric motor which supplies direct voltage to each of the individual motor coils to drive the motor. The driver comprises an input supply voltage which feeds the motor via three input terminals, a +vclcterminal, a middle point terminal, and a — vclcterminal. Each coil of the motor has two motor coil terminals, each connected via switches to various input terminals and other coils, the switches allowing a state in which a respective terminal is left open. The driver includes a controller to operate the switches in accordance with a switching protocol to control the electric motor.

[0044] Embodiments may comprise a driver for a brushless DC electric motor, which supplies direct voltage to each of two terminals of the individual stator coils to drive the motor. The driver comprises an input supply voltage which feeds the motor via three power terminals, a +vclcterminal, a middle point terminal, and a — vclcterminal. Each stator coil terminal of the motor is connected via switches to the power terminals and some of the terminals may be connected to those of other coils. The switches allow a state in which a respective terminal is left open. The driver includes a controller to operate the switches in accordance with a switching protocol to control the electric motor. Typically the stator coils of the motor each have one terminal which is selectively connected via switches to the positive power line or the neutral power line or to the negative power line. The second terminal is selectively connected to a common node and\or to the negative power line. The common node is selectively connected to the positive power line.

[0045] Before explaining at least one embodiment of the invention in detail, it is to be understood that the invention is not necessarily limited in its application to the details of construction and the arrangement of the components and / or methods set forth in the following description and / or illustrated in the drawings and / or the Examples. The invention is capable of other embodiments or of being practiced or carried out in various ways.

[0046] Reference is now made to Figure 3, which illustrates in simplified schematic form a three- level motor driver according to the present embodiments that may supply direct voltage for all the stator coils of a DC brushless motor with flexibility. The input supply voltage is split into three voltage levels, +vdc, middle point, and — vclc. The stator coil terminals are available to the control system at both ends; thus, in the case of three-coil motors, the driver has six driving terminals. A generic method may be applied to a multi-coil motor with five additional switches per coil.

[0047] In the present embodiments, the power source may often be energy storage systems such as a battery stack or a supercapacitor pack, or even an electric vehicle (EV) powertrain. The total amount of charge is the same as in the case of a single source, but may be split into two storage units with a local battery management system (BMS) per unit. Thus, in case of a malfunction in one of the packs, the local BMS disconnects the battery from the driver while the second pack is still available for use and the motor continues to operate. Such a feature may dramatically improve the reliability of the energy storage system. The driver of the present embodiments may alternatively be implemented in the case of an existing system with a single source by adding two identical series-connected capacitors or supercapacitors at the source terminal. The source is thus changed from a two port source into a three terminal source. The driver controller may thus balance the energy consumption in all available scenarios that may occur during the driver’s operation.

[0048] In the topology of Fig. 3, power source 30 has positive 32, neutral 34 and negative 36 power lines. Likewise each motor coil has two terminals, a, b and c, and a’, b’ and c’ . Switches QI ...Q3 switch terminals a, b and c to the positive power line 32. Switches Q4..Q6 connect a, b and c to the negative power power line 34. Q7 - Q9 connect terminals a’,b’ and c’ to the positive power line 32 but only if switch Q16 is set. Otherwise they connect terminals a’, b’ and c’ to each other. Switches Q10 - Q12 connect terminals a’, b’ and c’ to the negative power line 34. Switches Q13 - Q15 connect connect terminals a, b and c to the neutral power line 36. As referred to above, switch Q16 connects a common node 38 to the positive power line 32, so that terminals a’, b’ and c’ may be connected to the positive power line 32. If switch Q16 is not set then the terminals a’, b’ and c’ are connected to common node 38 as before but the effect is to connect the windings to each other.

[0049] In operation, with suitable switching of switches QI - Q15, a driver may supply the motor 4 2 1 1 1 1 2 coils with several voltage levels: 2vdc, -vdc, vdc, -vdc, -vdc, -vdc, 0, --vdc, --vdc, --vdc,

[0050] 4

[0051] —Vdc,~ ~Vdc^ and — 2vdc. In the case of a three coil motor, these voltages may produce an instantaneous motor coil current of 2idc, ide, 2 4

[0052] - - ide, -ide, - - ide, and -2idc(where idc= Vdc / rcoti). A switching algorithm may apply to the switches sequences of a 120° commutation, a 180° commutation, a PWM, and any other desired control protocol as elaborated in the background paragraph.

[0053] To understand the available connection for the driver, we assume a three coil motor with six terminals. For the six-step commutation of 120°, the required connection for half vdcis from the upper source throughout to coil terminal a to a’ (aa’), then over Q7and Q9to e’e coil passing thru Q15to the middle point as displayed in Figure 4. Fig. 4 illustrates the topology of Fig. 3, in which power source 30 has positive 32, neutral 34 and negative 36 power lines. Likewise each motor coil has two terminals, a, b and c, and a’, b’ and c’. Switches Q1...Q3 switch terminals a, b and c to the positive power line 32. Switches Q4..Q6 connect a, b and c to the negative power power line 34. Q7 - Q9 connect terminals a’,b’ and c’ to the positive power line 32 but only if switch Q16 is set. Otherwise they connect terminals a’, b’ and c’ to each other. Switches Q10 - Q12 connect terminals a’, b’ and c’ to the negative power line 34. Switches Q13 - Q15 connect connect terminals a, b and c to the neutral power line 36. As referred to above, switch Q16 connects a common node 38 to the positive power line 32, so that terminals a’, b’ and c’ may be connected to the positive power line 32. If switch Q16 is not set then the terminals a’, b’ and c’ are connected to common node 38 as before but the effect is to connect the windings to each other. Fig. 4 shows schematically an upper source six-step commutation of 120° phase with 0.5Vdcon each coil. The voltage over coils aa’ and bb’ correspondingly is 0.5vdcand — 0.5vdc. The current passing in the coils is 0.5idcat aa’ and — 0.5idcat bb’. In the same manner, more options are available but not disclosed here.

[0054] Fig. 5. Again illustrates the topology of Fig. 3. A power source 30 has positive 32, neutral 34 and negative 36 power lines. Likewise each motor coil has two terminals, a, b and c, and a’, b’ and c’. Switches Q1...Q3 switch terminals a, b and c to the positive power line 32. Switches Q4..Q6 connect a, b and c to the negative power power line 34. Q7 - Q9 connect terminals a’,b’ and c’ to the positive power line 32 but only if switch Q16 is set. Otherwise they connect terminals a’, b’ and c’ to each other. Switches Q10 - Q12 connect terminals a’, b’ and c’ to the negative power line 34. Switches Q13 - Q15 connect connect terminals a, b and c to the neutral power line 36. As referred to above, switch Q16 connects a common node 38 to the positive power line 32, so that terminals a’, b’ and c’ may be connected to the positive power line 32. If switch Q16 is not set then the terminals a’, b’ and c’ are connected to common node 38 as before but the effect is to connect the windings to each other. Fig. 5 illustrates a lower source six-step commutation of 120° phase 0.5Vdcon each coil. Another option for half vdcin a six-step commutation of 120° is with the lower source, from the middle point via Q14to coil bb’ terminal through Q8and Q9to c’c coil over Q6to the negative point of the lower source as displayed in Figure 5. The current passing in the coils is 0.5idcatbb’ and — 0.5idcat cc’. Additional alternatives, in similar means, are obtainable but not disclosed here. In this type of connection, the motor coil current is ±0.5idc.

[0055] An additional option for a six-step commutation of 120° is the sole two-level supply voltage and the combined supplied voltage. The two-level supply voltage per coil can be achieved by connecting a pair of coils from the positive terminal of the upper supply source to the negative terminal of the lower supply source. For example, such a path may pass from the positive terminal by Qi t° aa’ coil, passing Q10to the negative terminal of the lower source, and from the positive terminal by Q16and Q8to b’b coil, via Q5to the negative terminal of the lower source as presented in Figure 6. In this type of connection, the motor coil’s current is 2idcand — 2idccorrespondingly. Additional alternatives, in similar means, are obtainable but not disclosed here. Fig. 6 illustrates a two-level source six-step commutation of 120° with phase voltage of 2vdc. As before, power source 30 has positive 32, neutral 34 and negative 36 power lines. Likewise each motor coil has two terminals, a, b and c, and a’, b’ and c’. Switches QI ... Q3 switch terminals a, b and c to the positive power line 32. Switches Q4..Q6 connect a, b and c to the negative power power line 34. Q7 - Q9 connect terminals a’,b’ and c’ to the positive power line 32 but only if switch Q16 is set. Otherwise they connect terminals a’, b’ and c’ to each other. Switches Q10 - Q12 connect terminals a’, b’ and c’ to the negative power line 34. Switches Q13 - Q15 connect connect terminals a, b and c to the neutral power line 36. As referred to above, switch Q16 connects a common node 38 to the positive power line 32, so that terminals a’, b’ and c’ may be connected to the positive power line 32. If switch Q16 is not set then the terminals a’, b’ and c’ are connected to common node 38 as before but the effect is to connect the windings to each other.

[0056] The combined two-level and one-level coil voltage is available for a six-step commutation of 120° phase. In this alternative, one motor coil is connected to a two-level source, and the other is connected to a one-level source. As an example, coil aa’ is attached to the positive terminal of the upper source by Q1and to the negative terminal of the lower source by Q10, and coil b’b is attached from the positive terminal by Q16and Q8to b’b coil, via Q14to the middle point as exhibited in Figure 7. In this manner, the motor current in aa’ coil is 2idc, and the current in bb’ coil is idc. Additional alternatives, in similar means, are obtainable. Thus, Fig. 7 illustrates a combined two-level source and one-level source for six-step commutation with 120° phase with coil voltages of 2vdcand vclc. Parts in Fig. 7 that are the same as in previous figures are given the same reference numerals, which are not discussed again except as pertaining to an understanding of the present switching configuration.

[0057] Reference is now made to Fig. 8, which is a version of the topology of Fig. 3, illustrating a two-level source for six-step commutation with 120° phase with coil voltages of vdc. Parts in Fig. 8 that are the same as in previous figures are given the same reference numerals, which are not discussed again except as pertaining to an understanding of the present switching configuration. The two conducting coils are series connected to the two-level source in the last two-level connection option. For example, coil aa’ is attached to the positive terminal of the upper source by thru Q7and QQto coil b’b, continuing to the negative terminal of the lower source via Q5as presented in Figure 8. Fig. 8 illustrates a two-level source for six-step commutation with 120° phase with coil voltages of vdc. The current passing in the coils is idcat aa’ is idcand — idcat bb’ coil. Additional alternatives, in similar means, are obtainable.

[0058] The driver of the present embodiments may also support a 180° operation. The required connection for the upper source of vdcis may get throughout to coil terminal aa’, then over Q7 to Q8to b’b coil, passing thru Q14to the middle point and from Q9for c’c coil passing thru Q15to the middle point as displayed in Figure 9, which illlustrates upper source 180° commutation with a voltage of plus / minus two-thirds of vdcon one coil and plus / minus one-thirds of vdcon the other coils.

[0059] The voltage over coils aa’ is two-thirds of vdc, and for bb’ and cc’ is minus one-thirds of vdc. The current passing in the coils is two-thirds of idcat aa’ while the current at bb’ and cc’ is minus one-thirds of idc. More options, in the same manner, are available but not disclosed here.

[0060] A similar option may apply with the lower source vdc. The path can go from the middle point thru Q14to coil terminal bb’, then over Q8to Q7to a’ a coil, passing thru Q4to the negative terminal of the lower source, and from Q9to c’c coil passing thru Q6to the negative terminal of the lower source as shown in Figure 10. Fig. 10 illustrates a lower source 180° commutation with a voltage of plus / minus two-thirds of vdcon one coil and plus / minus one-thirds of vdcon the other coils.

[0061] The voltage over coils bb’ is two-thirds of vdc, and for aa’ and cc’ is minus one-thirds of vdc. The current passing in the coils is two-thirds of idcat bb’ while the current at aa’ and cc’ is minus one-thirds of idc. More options, in the same manner, are available but not disclosed here.

[0062] Another option is with the two-level source. The path can go from the upper positive terminal starting thru Q2to coil terminal bb’, then over Q8to Q7to a’ a coil, passing thru Q4to the negative terminal of the lower source, and from Q9to c’c coil passing thru Q6to the negative terminal of the lower source as shown in Figure 11. The voltage over coils bb’ is four-thirds of vdc, and the voltage across aa’ and cc’ coils are minus two-thirds of vdc. The current passing in the coils is four-thirds of idcat bb’ while the current at aa’ and cc’ is minus two-thirds of iclc. More options, in the same manner, are available but not disclosed here. Thus, Fig. 11 is a simplified diagram illustrating a two voltage-level source with 180° commutation with a voltage of plus / minus four- thirds of vdcon one coil and plus / minus two-thirds of vdcon the other coils.

[0063] Another option in a two-level variant is a mixture connection. The path can go from the upper positive terminal starting thru Q4to coil terminal aa’, then over Q10to the negative terminal of the lower source. And from the middle point thru Q15to cc’, then goes to Q9, continuing to Q8to b’b coil, passing thru Q5to the negative terminal of the lower source as displayed in Figure 12. The voltage over coils aa’ is two times vdc, the voltage across bb’ is minus half vdc, and half vdcon cc’. The current passing in the coils is twice idcat aa’ while the current at bb’ and cc’ is minus half idcand a half idccorrespondingly. In the same manner, more options are available but not disclosed here. Fig. 12 is a simplified diagram that illustrates a two voltage-level source with 180° commutation with a voltage of plus vdcon one coils, minus vdcon the other coils, and zero voltage on the last coil.

[0064] Another mixture connection is with the path that can go from the upper positive terminal starting thru to coil terminal aa’, then over Q7to switches Q8and Q9. From Q8, it continues to b’b and then passes thru Q5to the negative terminal of the lower source. As off Q9, continuing to c’c coil, through Q15to the middle point, as displayed in Figure 13. The voltage over coils aa’ is vdc, the voltage across bb’ is minus vdc, and zero voltage on cc’. The current passing in the coils is idcat aa’, while the current at bb’ is minus idcand zero at cc’ . In the same manner, more options are available but not disclosed here.

[0065] Fig. 13 is a simplified diagram showing a two voltage-level source with 180° commutation with a voltage of plus / minus four-thirds of vdcon two coils and plus / minus two-thirds of vdcon the one coil.

[0066] A further mixture connection according to the present embodiments concerns a path that may go from the upper positive terminal starting thru to coil terminal aa’, then over Q10to the negative terminal of the lower source. In addition, Q16connects coil b’b to the upper positive terminal with Q8, then passes thru Q5to the negative terminal of the lower source. And coil c’c is also connected to Q16throughout Q9, then passing Q15to the middle point, as displayed in Figure 14. The voltage over coils aa’ is twice vdc, the voltage across bb’ is minus twice vdc, and the voltage on cc’ is minus vdc. The current passing in the coils is two idcat aa’, while the current at bb’ is minus two idcand minus idcat cc’. In the same manner, more options are available but not disclosed here. Thus, Fig. 14 is a simplified diagram illustrating a two voltage-level source with 180° commutation and a voltage of plus / minus four-thirds of vdcon two coils and plus / minus two- thirds of vdcon the one coil.

[0067] A further option with the present embodiments is again with a two-level source. The path can go from the upper positive terminal starting thru Q1to coil terminal aa’, then over Q10to the negative terminal of the lower source. In addition, Q16connects coil b’b by Q8and Q5to the negative terminal of the lower source, and coil c’c by Q9and Q6to the negative terminal of the lower source as presented in Figure 15. The voltage over coil aa’ is two vdc, and the across bb’ and cc’ is minus two vdc. The current passing in the coils is two idcat bb’ while the current at aa’ and cc’ is minus two idc. More options, in the same manner, are available but not disclosed here. Thus, Fig. 15 is a simplified diagram illustrating a two voltage level-source with 180° commutation and a voltage of 2vdcand minus two vdcon another coil. Reference is now made to Fig. 16, which illustrates a simplified control scheme for the electric motor discussed herein. Electric motor control 160 is effected according to a drive sequence 162 in which the various coils are connected to each other and to the various power terminals and common node. The drive sequence may be any sequence that drives the motor and may use any of the systems mentioned herein.

[0068] The coils of the motor, typically the stator coils, each have two terminals, a first terminal and a second terminal. The first terminals 164 are selectively connected to the positive power line 166, the negative power line 168 and the neutral (or earth) power line 170. The second terminals 172 are selectively connected either to the negative power line 168 or common node 174, and the common node 174 is selective connected to the positive power line 166.

[0069] General

[0070] The terms "comprises", "comprising", "includes", "including", “having” and their conjugates mean "including but not limited to".

[0071] The term “consisting of’ means “including and limited to”.

[0072] The term "consisting essentially of" means that the composition, method or structure may include additional ingredients, steps and / or parts, but only if the additional ingredients, steps and / or parts do not materially alter the basic and novel characteristics of the claimed composition, method or structure.

[0073] As used herein, the singular form "a", "an" and "the" include plural references unless the context clearly dictates otherwise.

[0074] It is appreciated that certain features of the invention, which are, for clarity, described in the context of separate embodiments, may also be provided in combination in a single embodiment and the present description is to be construed as if such embodiments are explicitly set forth herein. Conversely, various features of the invention, which are, for brevity, described in the context of a single embodiment, may also be provided separately or in any suitable subcombination or may be suitable as a modification for any other described embodiment of the invention and the present description is to be construed as if such separate embodiments, subcombinations and modified embodiments are explicitly set forth herein. Certain features described in the context of various embodiments are not to be considered essential features of those embodiments, unless the embodiment is inoperative without those elements.

[0075] Although the invention has been described in conjunction with specific embodiments thereof, it is evident that many alternatives, modifications and variations will be apparent to those skilled in the art. Accordingly, it is intended to embrace all such alternatives, modifications and variations that fall within the spirit and broad scope of the appended claims.

[0076] It is the intent of the applicant(s) that all publications, patents and patent applications referred to in this specification are to be incorporated in their entirety by reference into the specification, as if each individual publication, patent or patent application was specifically and individually noted when referenced that it is to be incorporated herein by reference. In addition, citation or identification of any reference in this application shall not be construed as an admission that such reference is available as prior art to the present invention. To the extent that section headings are used, they should not be construed as necessarily limiting. In addition, any priority document(s) of this application is / are hereby incorporated herein by reference in its / their entirety.

Claims

WHAT IS CLAIMED IS:

1. An electric motor and driver, the electric motor having at least three coils, the driver having three driver terminals to supply three levels of direct voltage to said coils selectively to drive said motor; the motor coils each having first and second coil terminals respectively, respective first coil terminals being selectively connectable to all three of said driver terminals and respective second coil terminals being selectively connectible to two of said driver terminals or to others of said respective second coil terminals.

2. The electric motor and driver of claim 1, wherein said three driver terminals comprise a +vclcterminal, a middle point terminal, and a — vclcterminal.

3. The electric motor and driver of claim 1 or claim 2, wherein each coil terminal of said motor is connected via switches to respective ones of said driver terminals.

4. The electric motor and driver of claim 3, comprising a controller to operate said switches in accordance with a switching protocol to drive said electric motor.

5. The electric motor and driver of claim 4, wherein said switching protocol comprises combinations wherein ones of said motor coils are connected to others of said motor coils.

6. The electric motor and driver of claim 4 or claim 5, wherein said switching protocol includes combinations in which ones of said coil terminals are left open.

7. The electric motor and driver of any one of claims 3 to 6, wherein said three driver terminals comprise a +vclcterminal and wherein one of said switches is located to connect said +vdc driver terminal to a common node of said respective second coil terminals.

8. The electric motor and driver of any one of claims 3 to 7, wherein said switches are controllable to provide current paths between any combination of said plurality of motor coils.

9. The electric motor and driver of any one of claims 3 to 8, wherein said switches are controllable to provide 120 degree commutation.SUBSTITUTE SHEET (RULE 26)10. The electric motor and driver of any one of claims 3 to 9, wherein said switches are controllable to provide 180 degree commutation.

11. The electric motor and driver of any one of claims 3 to 10, wherein said switches are controllable to provide pulse width modulation.

12. The electric motor and driver of any one of claims 3 to 11, wherein said switches are controllable to provide a space vector-based switching algorithm.

13. The electric motor and driver of any one of the preceding claims, comprising three motor coils, and five switches per motor coil.

14. The electric motor and driver of any one of the preceding claims, comprising three motor coils, five switches per motor coil and one additional switch.

15. The electric motor and driver of any one of the preceding claims, comprising more than three motor coils, and five switches per motor coil.

16. The electric motor and driver of any one of the preceding claims, comprising more than three motor coils, five switches per motor coil and one additional switch.

17. A power source for the driver of any one of the preceding claims, the power source comprising a power train for an electric vehicle.

18. An electric motor having at least three coils, each coil extending between first and second terminals respectively, and wherein each of said first and second terminals are available to an external control system.

19. A control system to drive the motor of claim 14, comprising a DC power source having a positive power line, a negative power line and a neutral power line, and switches for selective connection, wherein one switch respectively connects each first terminal to said positive power line, one switch respectively connects each first terminal to said negative power line, one switch respectively connects each said first terminal to said neutral power line, one switch connects a common node of each said second terminal to said positive power line, one switch respectivelySUBSTITUTE SHEET (RULE 26)23 July 202416 connects each said second terminal to said common node, and one switch respectively connects each said second terminal to said negative power line.

20. A method of driving an electric motor, the electric motor having at least three coils, each coil extending between first and second terminals respectively, and wherein each of said first and second terminals are available to an external control system, the method comprising: selectively connecting each of said first terminals to a positive power line of a DC power source, to a negative power line of said DC power source and to a neutral power line; selectively connecting each of said second terminals to a common node or to said negative power line; and selectively connecting said common node to said positive power line, and wherein said selectively connecting of said first terminals, said second terminals and said common node is in accordance with a predetermined drive sequence.SUBSTITUTE SHEET (RULE 26)

Images