ELECTRIC MACHINE WITH INTEGRATED POWER ELECTRONICS

Abstract

A rotary electric machine may include a motor portion and an inverter portion. The motor portion may include a stator, a plurality of coils, circumferentially disposed around the stator and connected to form a plurality of galvanic isolated winding sections each having a subset of the coils connected in a multi-phase configuration and each of which may be provided with a coil terminal, and a rotor with a number of pole pairs rotatably disposed against a stator magnetic field generated by currents in the coils. The inverter portion may include a plurality of power switching elements connected to form a number of half bridge legs, and further comprising a high side power switching element, a low side power switching element in each half bridge leg, and an output connector at each half bridge leg. The number of half bridge legs may be equal to a number of isolated winding sections multiplied by a number of phases of the multi-phase configuration. The output connector of each half bridge leg may be connected to an individual coil terminal.

Claims

1. A rotary electric machine with integrated power electronics, comprising: a motor portion comprising: a stator; a plurality of coils, circumferentially disposed around the stator, said coils being connected to form a plurality of galvanic isolated winding sections, wherein each winding section has a subset of the coils, which are connected in a multi-phase configuration and each of which is provided with a coil terminal; a rotor with a number of pole pairs rotatably disposed against a stator magnetic field generated by currents in the coils; an inverter portion comprising: a plurality of power switching elements; wherein said power switching elements are connected to form a number of half bridge legs, and are further comprising a high side power switching element, a low side power switching element in each half bridge leg, and an output connector at each half bridge leg; wherein said number of half bridge legs is equal to a number of isolated winding sections multiplied by a number of phases of the multi-phase configuration; and wherein the output connector of each half bridge leg is connected to an individual coil terminal.

2. The machine according to claim 1, wherein the inverter portion is provided with current sensors for measuring the currents in said winding sections.

3. The machine according to claim 2, wherein said current sensors are arranged to measure the currents in only one of the isolated winding sections.

4. The machine according to claim 2, wherein said current sensors are arranged to measure the currents in only two coils of a single winding section.

5. The machine according to claim 2, wherein the number of pole pairs on the rotor is greater than two and that said current sensors are arranged to measure the currents in only two of the isolated winding sections.

6. The machine according to claim 5, wherein said current sensors are arranged to measure the currents in each of the two isolated winding sections only in two coils of the respective isolated winding section.

7. The machine according to claim 5, wherein at least four current sensors are provided, wherein said four current sensors are arranged to measure: the currents in a first isolated winding section in two coils of the first isolated winding section, said two coils being assigned to a first and second phase of the multi-phase configuration; and the currents in a second isolated winding section in two coils of the second isolated winding section, said two coils being assigned to the first and second phase of the multi-phase configuration.

8. The machine according to claim 2, wherein the number of pole pairs on the rotor is four, and said current sensors are arranged to measure the currents in all four isolated winding sections.

9. The machine according to claim 8, wherein said current sensors are arranged to measure the currents in the respective isolated winding section in only six coils of said isolated winding section.

10. The machine according to claim 8, wherein at least six current sensors are provided, wherein said current sensors are arranged to measure: the currents in a first isolated winding section in two coils of the first isolated winding section, said two coils being assigned to a first and second phase of the multi-phase configuration; the currents in a second isolated winding section in two coils of the second isolated winding section, said two coils being assigned to the first and second phase of the multi-phase configuration; the currents in a third isolated winding section in a coil assigned to the first phase of the multi-phase configuration; and the currents in a fourth isolated winding section in a coil assigned to the first phase of the multi-phase configuration.

11. The machine according to claim 2, wherein said current sensors are directly connected to the respective isolated winding section in an area of the respective terminal.

12. The machine according to claim 1, wherein the number of said galvanic isolated winding sections is equal to the number of pole pairs on the rotor.

13. The machine according to claim 1, wherein the number of pole pairs on the rotor is even the number of said galvanic isolated winding sections is half the number of pole pairs on the rotor.

14. The machine according to claim 1, wherein said winding sections are all electrically identical.

15. The machine according to claim 1, wherein the inverter portion is provided with a positive DC link bus connection and a negative DC link bus connection, connecting all half bridge legs to a DC link capacitor bank.

16. The machine according to claim 1, wherein the number of said half bridge legs is equal to the number of coils in the stator.

17. The machine according to claim 1, wherein a Field Oriented Control algorithm is provided for controlling the electric machine operation based on current measurements in one from the plurality of said galvanically isolated winding sections.

18. The machine according to claim 1, wherein all half bridge legs are embodied substantially identical and arranged uniformly in a circumferential direction.

19. The machine according to claim 1, wherein all half bridge legs, which are connected to the coils of the same phase in different winding sections, are connected with the same driver elements for simultaneously switching the half bridge legs.

20. A rotary electric machine with integrated power electronics, comprising: a motor portion comprising: a stator; a plurality of coils, circumferentially disposed around the stator, said coils being connected to form a plurality of galvanic isolated winding sections, wherein each winding section has a subset of the coils, which are connected in a multi-phase configuration and each of which is provided with a coil terminal; and a rotor with a number of pole pairs rotatable disposed against a stator magnetic field generated by currents in the coils; and an inverter portion comprising a plurality of power switching elements connected to form a number of half bridge legs, and further comprises a high side power switching element, a low side power switching element in each half bridge leg, and an output connector at each half bridge leg; wherein said number of half bridge legs is equal to a number of isolated winding sections multiplied by a number of phases of the multi-phase configuration, and said number of isolated winding sections is equal to said number of pole pairs on the rotor; wherein the output connector of each half bridge leg is connected to an individual coil terminal; and wherein the inverter portion is provided with current sensors for measuring the currents in said winding sections.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0030] FIG. 1 is a block diagram of an electric machine with integrated electronics with the connections of motor parts with the inverter parts.

[0031] FIG. 2 is a circuit diagram of the driver circuitry for driving the power switches, which belong to the same motor phase; example shown is for the phase U.

[0032] FIG. 3 is a block diagram of the motor part of FIG. 1 but in another embodiment.

DETAILED DESCRIPTION

[0033] According to FIG. 1 an electric machine 1, which can be also addressed as motor, with integrated power electronics comprises a motor portion 11 and an inverter portion 2. The motor portion 11 comprises a stator 17, which is further comprising a plurality of galvanic isolated winding sections 12. The number of isolated winding sections 12 is so selected that it is equal to a number of pole pairs Npp on the rotor 14. The number of pole pairs Npp can be four for example. Each isolated winding section 12 has coils 10 preferably connected in star connection and forming a three phase winding section 12 essentially similar to another isolated winding section 12. The rotor 14 has said number of pole pairs Npp, which are rotatable disposed against the stator magnetic field generated by currents in the stator windings 12. Power switches 5 and 6 in the inverter part 2 are so arranged to form a plurality, i.e. a number Nhb of half bridge legs 18 with preferably only one power switch element 6 on the upper side and one power switch element 5 on the lower side of the half bridge leg 18 (FIG. 1). Output contacts 7 of the half bridge leg 18 are individually connected with coil ends 13 of the winding sections 12. All high side switches 6 are connected with their positive terminal to a DC link buss bar 4 which is essentially connected with a main power terminal B+ of the complete unit. Accordingly, all low side switches 5 are connected with their negative terminal to a negative DC link buss bar 3, which is further connected with the main power terminal B of the complete unit. Accordingly, all half bridge legs 18 are connected via the positive and negative link bus bars 3 and 4 to a DC link capacitor bank 21 consisting of at least one capacitor Cb Preferably, the DC link capacitor bank 21 consists of several capacitors Cb connected in parallel. The power switches 5 and 6 are excited from the driver circuitry 16 which provides a PWM (Pulse Width Modulation) signal so, that the coils 10 which belong to the same phase of the motor 1 are having essentially the same voltage within all isolated winding sections 12 at any time.

[0034] For the example shown in FIG. 1 this means, that the voltage signal applied to winding terminal U1 in the first winding section 12 is significantly the same as the voltage applied to winding terminal U2 in the second winding section 12 and so on the same through all the winding sections 12 in the motor-generator.

[0035] According to FIG. 2 a driver circuitry 16 comprises drivers 20 for high side power switches 6 and drivers 19 for the low side power switches 5 so that one high side driver output is connected to half bridge legs which belong to the same phase in the motor 1 through the resistors Rp. By this connection the number of drivers 19, 20 necessary to excite all the power switches 5, 6 is minimized to one for the high side and one for the low side exciting all coils 10 which belong to the same phase U, V, W in the motor 1 and this in all winding sections 12 in the motor 1. Consequently for the three phase motor inverter assembly the necessary numbers of drivers 19, 20 remain only three for the high side and three for the low side.

[0036] According to FIG. 1 current sensors 8 and 9 are so arranged that they measure the currents in only one from the plurality of winding sections 12 in the motor 1. Further it is suggested to measure the current with sensor 8 in only one coil 10 and with sensor 9 the current in a second coil 10 from the plurality of coils 10 in the motor stator 17. Their output values are processed in a control board 15 and the resulted PWM signal is output to the input of the driver circuitry 16. By this proposal the currents through current sensors 8, 9 are Npp times lower than the currents that would flow in the conventional motor configuration with just one winding in the stator. Consequently the size and the measuring range for the current sensors 8, 9 like in this proposal are reduced by Npp times. In a motor control algorithms, e.g. in an FOC (Field Oriented Control) algorithm, the measured values from the current sensors 8, 9 need to be multiplied with Npp in order to scale the motor current with the motor constant and so to control properly the requested motor torque output.

[0037] The invention can be summarized as follows. An electric machine 1 is provided which has integrated electronics and operates as an electric motor-generator in electrically powered systems. Said machine 1 has a motor portion 11 with a plurality of coils 10 so connected, to form a number of isolated winding sections 12 with multi-phase configuration, which are substantially identical between each other. Said motor portion 11 also has a rotor 14 with a number of pole pairs equal to said number of isolated winding sections 12. An inverter portion 2 of the machine 1 has a plurality of power switching elements 5, 6 forming a power stage with a number of half bridge legs 18. Output connectors 7 of said half bridge legs 18 are electrically connected to terminals 13 of individual coils 10. A control board in an ECU (Electronic Control Unit) of the inverter portion 2 provides such a control algorithm and signals for power switching, that the coils 10, which belong to the same phase of the machine 1, have the same terminal voltages. Current sensors 8, 9 for measuring the motor phase currents are so arranged to measure the currents through only two coils 10 from the plurality of coils 10 in the stator 17. The size, the measuring range of current sensors 8, 9 and unwanted braking torque during faults in motor windings or in power switches are reduced by the number of isolated winding sections 12. Therefore the motor-generator 1 becomes more compact and has a higher functional safety.

[0038] FIG. 3 depicts the motor portion 11 with the stator 17 and the rotor 14. In this preferred embodiment the number of pole pairs is greater than two and also greater than three. In the depicted example exactly four pole pairs are provided. To each pole pair a galvanic insulated winding section 12 is assigned, namely a first winding section 12.sub.1, a second winding section 12.sub.2, a third winding section 12.sub.3 and a fourth winding section 12.sub.4. The machine 1, respectively the motor portion 11 has a three phase configuration. The three phases are named U, V, and W, or first, second and third phase, respectively. By way of simplification, the phases can be named first phase U, second phase V and third phase W. It is understood that this correlation between the phases U, V, and W, on the one hand, and first, second and third phase, on the other hand, can be different. Each coil 10 comprises a winding for each phase, which are galvanic isolated. Said windings of the coils 10 are formed by sub-sections of the winding section 12. Therefore, twelve sub-sections are defined as follows, namely sub-portions U1, V1, W1 for the three phases in the first winding section 12.sub.1, U2, V2, W2 for the three phases in the second winding section 12.sub.2, U3, V3, W3 for the three phases in the third winding section 12.sub.3, and U4, V4, W4 for the three phases in the fourth winding section 12.sub.4.

[0039] In FIG. 3 the current sensors 8, 9 depicted in FIG. 1 have the reference sign S.

[0040] In a first embodiment exactly four current sensors S are provided, namely a first current sensor S1, a second current sensor S2, a third current sensor S3, and a fourth current sensor S4. Said current sensors S1, S2, S3, S4 are arranged to measure the currents in only two of the isolated winding sections 12, namely in the first winding section 12.sub.1, and a second winding section 12.sub.2. The first current sensor S1 is assigned to the first sub-section U1 of the first winding section 12.sub.1. The second current sensor S2 is assigned to the first sub-section U2 of the second winding section 122. The third current sensor S3 is assigned to the second or third sub-section V1 or W1 of the first winding section 12.sub.1. The fourth current sensor S4 is assigned to the second or third sub-section V2 or W2 of the second winding section 122. It is important that the first and second current sensors S1, S2 are assigned to sub-sections of the same phase, here the first phase U, and that the third and fourth current sensors S3, S4 are assigned to another phase, either both to the second phase V or both to the third phase W, here the third phase W.

[0041] These four current sensors S1, S2, S3, S4 therefore are arranged to measure the currents in the first isolated winding section 12.sub.1 in two coils 10 being assigned to the first phase U and to the second or third phase V, W, and the currents in the second isolated winding section 12.sub.2 in two coils 10 being assigned to the first phase U and to the second or third phase V, W. In this configuration one of the three phases in not detected, here the second phase V.

[0042] In another embodiment, which is depicted in FIG. 3, exactly six current sensors are provided, namely the aforementioned four current sensors S1, S2, S3, S4, and also a fifth current sensor S5 and a sixth current sensor S6. The fifth current sensor S5 is assigned to the first sub-section U3 of the third winding section 12.sub.3 and is thus assigned to the first phase U. The sixth current sensor S6 is assigned to the first sub-section U4 of the fourth winding section 124 and is thus also assigned to the first phase U.

[0043] These six current sensors S1, S2, S3, S4, S5, S6 are arranged to measure the currents in the first isolated winding section 12.sub.1 in two coils 10 assigned to the first and second phase U, V, the currents in the second isolated winding section 12.sub.2 in two coils 10 being assigned also to the first and second phase U, V, the currents in the third isolated winding section 12.sub.3 in a coil 10 assigned to the first phase U, and the currents in the fourth isolated winding section 12.sub.4 in a coil 10 assigned also to the first phase U. Also in this configuration one of the three phases, here the second phase V is not detected.

[0044] As can be seen in FIGS. 1 and 3 said current sensors 8, 9 or S1, S2, S3, S4, S5, S6, respectively, are directly connected to the respective isolated winding section 12 or sub-section U1, U2, U3, U4, V1, V2, V3, V4, W1, W2, W3, W4, respectively, in the area of the respective terminal 13. In other words, the respective connection is arranged between the respective sub-section and the respective power switching elements 5, 6.