EP2022163A1

EP2022163A1 - Triphase rotating electric machine

Info

Publication number: EP2022163A1
Application number: EP07766025A
Authority: EP
Inventors: Hugues Doffin; Farouk Boudjemai; Ertugrul Taspinar; Julien Masfaraud
Original assignee: Valeo Equipements Electriques Moteur SAS
Current assignee: Valeo Equipements Electriques Moteur SAS
Priority date: 2006-06-01
Filing date: 2007-05-10
Publication date: 2009-02-11
Also published as: WO2007138211A1; US20100231152A1; FR2901927A1; FR2901927B1; US8115432B2; CN101479922A; CN101479922B

Abstract

A triphase rotating electric machine includes three coils (2) evenly distributed around a rotational axis of the machine, and at least one first sensor (4), capable of generating a periodic signal to represent the position of the machine around said axle and a control circuit (8) capable of controlling, when in the first mode, the conduction of a switch (KUH), linked to at least one of the three coils (2) based on the periodic signal generated by the first sensor (U), such that the conduction phases of the switch (KUH) have a duration in the order of half the signal period (U). The control circuit is capable of controlling the switch (KUH), based on a second mode in which the conduction phases of the switch (KUH) have a duration in the order of a third of the signal period (U).

Description

THREE-PHASE ELECTRIC ROTATING MACHINE

The invention relates to a reversible three-phase electric rotating machine of the alternator-starter type.

In this type of machine operating as a starter, different coils regularly spaced around a part of the machine (usually the stator) are fed successively by a set of switches to generate a rotating magnetic field which causes the drive the other part of the machine (usually the rotor) fed continuously.

For example, in the case of a delta configuration of the windings (or phases) of the stator, the windings are fed by the set of switches so as to subject each of the common nodes to two coils, ie to a first voltage ( for example positive), or at a second voltage (for example zero). Proper control of the switches thus makes it possible to reverse the current flowing through each winding during a period of rotation of the machine and thus to generate the rotating field mentioned above.

In order to generate the control signals of the switches aiming to obtain such control, a practical solution consists in placing equidistant sensors around the rotating machine (here three sensors in the case of a three-phase machine) and in controlling the switches by means of signals generated by these sensors (directly for the switches applying the first voltage, and with a signal inversion for the switches applying the second voltage), according to a technique generally called "full wave control".

However, according to this solution, the signals from the sensors consisting of two alternations (one positive, the other negative) each extending over half of the signal period (that is to say 180 ° in terms of phase), the following configuration is obtained at each instant: each node located between two windings in a delta configuration is connected to one of the voltage sources (because at each moment one of the switches associated with it is closed) and two nodes on the three are thus connected to the same voltage source and thus short circuit the winding which separates them.

As a result, the equivalent resistance of the rotating machine is only half the resistance of a winding, which can be problematic under certain operating conditions.

This is for example the case for rotating machines intended to assist a heat engine during its acceleration phases and whose windings are sized with a low stator resistance in order to provide a high mechanical power at high speed. The currents involved in the low resistance can be destructive for the electronics in other operating circumstances, such as for example the starting of the engine under a large voltage.

The problems described above have been presented in the particular case of a stator having a configuration of the triangle windings. Note, however, that these problems also exist in the case of a star configuration.

The invention proposes a three-phase electrical rotating machine of the alternator-starter type comprising three coils regularly distributed around an axis of rotation of the machine, at least one first sensor capable of delivering a periodic signal representative of a position of the machine around said axis and a control circuit capable of controlling, in a first mode (said 180 ° control), the conduction of a switch associated with at least one of the three windings on the basis of the periodic signal delivered by the first sensor of so that the conduction phases of the switch have a duration of the order of half the period of the signal, signal. The switch is part of a switch bridge with three branches, each branch corresponding to a phase and having at least two switches.

According to the invention, the control circuit is able to control the switch according to a second mode (called control 120 °) in which the conduction phases of the switch have a duration of about one third of the period of the signal.

In the case of a triangle configuration of the windings of the machine, the first mode is that allowing a low stator resistance and the second mode is that allowing increased stator resistance. In the case of a star configuration of the windings of the machine, the second mode is that allowing a low stator resistance and the first mode is that allowing increased stator resistance. As will become clear in the following, the passage into a suitable driving mode, according to the triangle or star configuration of the machine windings, allows an increase in the resistance of the rotating machine and thus a reduction of the current, advantageous under certain conditions as mentioned above. The control circuit may include selection means for selectively activating the first mode or the second mode. The control mode can thus be chosen according to the operating conditions.

The selection means can, according to a first possibility, activate the first mode or the second mode as a function of a rotational speed information of the machine, for example when said speed information indicates a speed of rotation lower than a first threshold.

This avoids the aforementioned problems that occur at low speeds of rotation.

The selection means can according to a second possibility (possibly combinable with the first) activate the first mode or the second mode depending on a voltage of a battery supplying the machine, for example when the battery voltage is less than one. second threshold. This restores the voltage of the battery by reducing the aforementioned current, which limits the voltage drop encountered in certain phases of operation. The control circuit may comprise in practice means for generating, in the second mode, a control signal intended for the switch formed at least on the basis of a combination of the signal delivered by the first sensor and a signal delivered by a second sensor.

For example, said means for generating the control signal comprise a first logic circuit capable of performing an exclusive or operation between the signal delivered by the first sensor and the signal delivered by the second sensor. This results in control in 120 ° mode by means relatively simple to implement. Said means for generating the control signal may comprise a second logic circuit capable of performing an AND logic operation between the signal delivered by the first sensor and the result of the OR-EXCLUSIVE logic operation in order to obtain the control signal of the switch. Said means for generating the control signal may also comprise means for advancing by 30 ° the phase of the signals applied to the first logic circuit, which makes it possible to generate a control signal formed of slots of 120 ° centered on the slots of 180 ° present in the signal from the first sensor. Other characteristics and advantages of the invention will become apparent in the light of the description which follows, made with reference to the appended drawings in which:

- Figure 1 shows an embodiment of a rotating machine according to the teachings of the invention; FIG. 2 represents an exemplary implementation possible for the signal generator circuit of FIG. 1;

FIG. 3 represents an exemplary implementation possible for the circuit G1 of FIG. 2;

FIGS. 4a to 4e are timing diagrams that illustrate the behavior of the various signals involved in FIG. 3;

FIG. 5 represents a first part of another possible embodiment for the signal generator circuit of FIG. 1;

FIG. 6 represents a second part of the circuit of FIG.

With reference to FIGS. 1 to 6, the invention is now essentially described in the form of a three-phase rotating electrical machine of the type having a configuration of delta windings. However, it should be clear to those skilled in the art that the invention relates to two conventional types of three-phase rotating electrical machine, namely, triangle machines and star machines. Figure 1 shows the overall electrical diagram in which is implanted a three-phase rotating electrical machine according to the teachings of the invention. For the sake of simplification, only the stator 2 of the rotating electrical machine is shown in FIG. 1; the rotating machine also comprises a rotor driven by the rotating magnetic field formed by the stator 2 as described below. The stator 2 is formed of three windings (or coils) regularly arranged on the circumference of the rotating machine and therefore each spaced 120 °.

The windings are connected in a triangle. Each node of this circuit separating two windings is connected to a pair of switches, a first switch K _UH , K _VH , K _WH being able to connect the node concerned to the positive voltage V _B AT of a battery 6, the second KUB switch, K _V B, K _W B being adapted to connect the node concerned to ground.

The switches are controlled by control signals generated by a signal generator 8 whose operation is described in detail below. In the following C Onι is noted the control signal associated with the switch Kχι (that is to say for example C _UH the control signal for the switch K _UH ) -

Position sensors 4 distributed over the circumference of the rotating machine provide information U, V, W relating to the position of the rotor and which are therefore used by the signal generator 8 for the construction of the switch control signals, as described in detail below.

The sensors may be of the all-or-nothing (discrete) or linear type depending on the embodiment envisaged as explained below.

The signal generator is able to deliver the control signals CUH, CUB, CVH, CVB, CWH, CWB to the switches according to two main modes of operation:

an operating mode in which the signals U, V, W coming from the sensors are transmitted to the switches as control signals, possibly to a possible inversion, which causes the opening and closing of each switch per half-period (180 ° steering);

a mode of operation in which the signals from the sensors are processed so that the control signals generated by the Signal generator 8 causes the conduction of each switch only during a third period (control 120 °).

In all cases, the control signals are furthermore such that two switches associated with the same node (such as switches K _UH and K _UB ) are never closed at the same time. Note, however, that the two switches associated with the same node are simultaneously open in certain phases in operating mode "control 120 ^® .

The operating mode (180 ° control or 120 ° control) is chosen at each moment according to the operating conditions of the system, for example according to the methods described herein.

In the embodiment described here, a measuring circuit 10 of the speed of rotation of the machine (here realized by a microprocessor which receives the position information U, V, W) transmits a control signal C _N to the signal generator 8 as a function of the measured rotation speed N. The signal generator 8 switches its operating mode between the two operating modes mentioned above according to the control signal C _N received from the measuring circuit 10.

According to an embodiment adapted for example to rotating machines intended not only to start a heat engine, but also to assist it during faster rotations, it is expected that the measuring circuit 10 generates a control signal C _N imposing a functioning in "180-direction control" mode when the measured rotational speed N is greater than a threshold N ₀ , while this control signal C _N requires operation in "control mode at 120""when the measured rotational speed N is below the threshold N ₀ . In practice, for example, N ₀ = 600 rpm is used.

This benefits from the high torque allowed by the 180 ° control in the engine assistance phases (high speed rotation), while the current is limited by the 120 ° control in the low speed rotation phases ( such as, for example, starting the heat engine). Indeed, when driving at 120 °, a node of the stator 2 is left free (that is to say not connected) at each moment, so that the equivalent resistance of the stator is worth two thirds of the resistance of a winding, which allows a maximum current reduction of about 30% compared to the case of 180 ° control described in introduction. Of course, the current reduction is dependent on the resistors present in the circuit and in particular the resistance of the battery.

In the embodiment described here, a detector 12 of the value of the voltage V _BAT of the battery 6 is also provided in order to send a control signal C _v to the signal generator 8 which forces it to an operating mode. type "120" control "when the voltage V _BAT falls below a voltage threshold (for example 10.5V for a battery providing a voltage of 12V.

Tilting in 120 ° control mode allows a reduction of the current as explained above and therefore a reduction of the voltage drop at the battery.

As the voltage drop measured by the detector 12 is generally created by untimely phenomena, the detector 12 will preferably be made in hardware (and not software) form in order to obtain a sufficiently fast tilt (of the order of 100 μs). of the operating mode.

FIG. 2 represents an exemplary embodiment of the signal generator 8 of FIG. 1.

In this example, the signal generator comprises a first part intended to generate the control signals AUH, AUB, A _V H, A _V B, A _W H, A _W B for the operating mode of the 180 ° control type.

These signals are therefore directly derived from the sensor signals U, V,

W for the AUH, A _V H, A _W H signals for the KUH, K _V H, K _W H switches which are connected to the positive voltage V _BAT of the battery and formed by simple inversion of the U, V, W sensor signals for the control signals AUB, A _V B, A _W B for switches KUB, K _V B, K _W B linked to the ground.

As a variant, it would naturally be possible to process the U, V, W sensor signals to obtain control signals intended for 180 ° control, for example a threshold detection in order to transform the signals coming from the sensors into all or nothing signals. for example when the sensors are of the linear type.

The signal generator shown in FIG. 2 also comprises a part able to form control signals BUH, BUB, B _V H, BVB, BWH, BWB for controlling 120 ° from the same sensor signals U, V, W. To do this, use is made of circuits G ₁ , G ₂ , G ₃ , an example of which will be given hereinafter and which make it possible, from the signals of at least two sensors (for example U and V) to generate a control signal (for example B _UH ) capable of causing the conduction of the associated switch (here K _UH ) for only one third of a period (driving 120 °), as well as the control signal of the switch associated with the same node (here K _UB ) with a period of conduction equal again to a third of period.

The set of control signals mentioned above (namely on the one hand the signals A _X | and on the other hand the Bχι signals) are transmitted to the input of a switch S able to select as a signal command Cχι for the switch Kχι, the corresponding signal Aχι for driving

180 °, the corresponding signal B _X ι for 120 ° control.

The selection of the switching made by the switch S is carried out as already indicated on the basis of the control signals C _N and Cv mentioned above. For example, if the value 1 of each of these signals implies a control of 120 °, these signals Cv, C _N are combined by means of an OR logic operator in order to switch to a 120 ° piloting mode as soon as one of the conditions mentioned above for this purpose is met.

An embodiment of the processing circuits Gi, G ₂ and G ₃ will now be described. However, it will suffice to describe the structure of the circuit G ₁ , the structure of the other two circuits being easily deduced.

FIG. 3 represents a first exemplary embodiment of the circuit G1 of FIG. 2.

In this example, the circuit G ₁ comprises an XOR circuit receiving as input the U and V signals received from the sensors and generating as output the result of a logic operation of or exclusive between these two values. We note this result U®V.

The output of the XOR circuit is applied on the one hand to the input of an AND gate which also receives as input the sensor signal U and thus emits the control signal B _UH for the control 120 ° of the switch K _UH -

The signal emitted by the XOR circuit is also applied to the input of another AND gate which receives on its other input the signal ÏI which allows thus to form the control signal B _UB for the control 120 ° of the switch K _UB -

FIGS. 4a to 4e show the behavior during a period (phase Φ represented as abscissa) of the various signals present in the circuit of FIG. 3a.

FIGS. 4a and 4b respectively represent the signals emitted by the corresponding sensors, the signal V having a phase advance of 120 ° with respect to the signal U due to the arrangement of the sensors.

FIG. 4c represents the U V signal formed by the XOR circuit. Due to the use of a logic or exclusive, the non-zero parts of the signal U®V correspond to the instants where only one of the signals U and V is not zero, which makes it possible to generate slots of a width of 120 ° (from the signals U and V both formed of slots width 180 °).

FIGS. 4d and 4e respectively represent the control signals B _UH and B _UB obtained with the aid of the circuits of FIG. 3: the slots of the signal U®V visible in FIG. 4c are found alternately in only one of the signals control unit B _UH and B _UB by the respective application of signal U and signal U by means of AND gates.

A second embodiment of the signal generator 8 of FIG. 1 will now be described with reference to FIGS.

In this exemplary embodiment, control signals in phase with the 180 ° signals received from the corresponding sensor are formed for the operating mode 120 °.

The example described here uses linear sensors (sometimes referred to as "pseudo-sinus").

The parts of the generator circuit capable of generating the control signals C _UH and C _UB for the switches K _UH and K _{UB are} described in detail below, the other parts intended to form the other control circuits deriving therefrom by analogy . As can be seen in FIG. 5, the signal U coming from a sensor is applied to the positive input of a comparator AO1 through a resistor R1. The operational amplifier is supplied in a conventional manner with a voltage V ₁ (here V ₁ = I ₅ V).

The comparator AO1 receives on its negative input the signal W through a resistor, also of value R1. It will also be noted that on each of the inputs of the comparator

AO1 is also applied through a resistor R2 the combination of the three sensor signals U, V, W, this combination being obtained by applying each of the signals to a common node through a resistor R3. In practice, R2 = 120 kΩ and R3 = 8.2 kΩ. This application of the combination of the three signals allows to always work with positive signals.

The output of the comparator AO1 is connected to a voltage source V ₀ (here, V ₀ = 5V) through a resistor R4 (here R4 = 4.7 kΩ). Thus, by virtue of the subtraction of the signal W from the signal U implemented by the comparator AO1 and thanks to the linearity of the signals due to the sensors used, the output of the amplifier is obtained a periodic signal U _{+ 3} o in advance of phase of 30 ° with respect to signal U.

As visible in FIG. 5, the signals V and U are respectively applied to the positive and negative input of a comparator AO2 in order to obtain a periodic signal V ₊ 30 at the output of 30 ° compared to the V signal.

Likewise, the signals W and V are respectively applied to the positive and negative input of a comparator AO3 in order to obtain at the output a periodic signal W _{+ 30} in phase advance of 30 ° with respect to the signal W. However, since this signal W _{+ 30} is not used for the construction of the control signals C _UH and C _UB described here, it will not be mentioned hereinafter. It is naturally used in practice for the construction of the other control signals according to a technique similar to that described now.

The signals in phase advance of 30 ° U _{+ 30} and V _{+ 30} are respectively applied to the two inputs of a logic circuit performing an exclusive operation, in order to obtain a signal noted U ₃₀ ΘV ₃₀ . According to the embodiment described here, this signal U30ΘV30 is used to form the control signals C _UH and C _UB as illustrated in Figure 6 and described below.

According to one conceivable variant, this signal U ₃ o V V ₃ o could be used in place of the U®V signals in the embodiment of FIG. 3. This would give slots of the same type as those illustrated in FIGS. and 4th, but centered on the slots (length 180 °) of Figure 4a through the phase advance of 30 °. The logical combination U ₃ o © V ₃ oU applies in this case. Returning to the second embodiment, the part of which is now described is illustrated in FIG. 6, it is observed that one applies successively to the signal U ₃₀ ΘV ₃₀ :

an inversion by means of an inverter circuit I;

the possible addition of a MLI signal composed of high frequency slots, the addition being able to be carried out or not according to the command received from a PWM-ON signal, for example sent by the microprocessor 10 as a function of the operating conditions . It will be noted that the addition of a PWM signal may advantageously make it possible to reduce the average current in the critical phases. A MODUL signal is thus obtained capable of modulating the signal U during the operating mode in 120 ° control as described below.

Indeed, for this purpose, a transistor T controlled by a MODE signal indicative of the driving mode (180 ° mode or 120 ° mode) is able to transmit (blocked transistor) or not (conductive transistor, which causes the setting to the signal mass MODUL) the signal MODUL at the control input of two multiplexers M1, M2 (for example of the type 74HC153). The signal MODE is for example obtained by the logical combination by means of an OR operator of the signals C _N and C V as indicated in the first embodiment.

It may be noted that the transistor T thus participates in switching between the two operating modes (function performed by the switch S in the first embodiment). The multiplexer M1 is also powered on its first input by the sensor signal U while its second input is grounded.

Thus, when the MODE signal indicates a control mode at 180 °, the control signal is permanently zero so that the multiplexer M1 outputs a signal C _UH identical to the signal U received on its first input.

On the other hand, when the MODE signal indicates a control mode at 120 °, the control signal is the previously built MODUL signal (mainly by inversion of U30ΘV30) so that the output C _UH of the multiplexer M1 is forced to 0 (value of the second input of M1) when the signal MODUL is high (that is to say mainly when the signal U ₃ oθV ₃ o is low) and follows the signal U the rest of the time.

A signal C _{UH is} thus obtained whose phases which control the conduction of the switch K _UH extend over 120 ° and are centered with respect to the high periods of the signal U. Similarly, the signal C _UB is obtained as illustrated in FIG. FIG. 6 by applying the signal U to the first input of the multiplexer M2 and setting high potential V ₀ of its second input, with inversion by means of an inverter circuit I '.

Claims

1. Three-phase electrical rotating machine of alternator-starter type comprising three coils regularly distributed around an axis of rotation of the machine, at least one first sensor capable of delivering a periodic signal representative of a position of the machine about said axis and a control circuit capable of controlling, in a first mode, the conduction of a switch associated with at least one of said three windings on the basis of the periodic signal delivered by the first sensor so that the conduction phases of the switch have a duration of the order of half the period of the signal, said switch forming part of a three branch switch bridge, each said branch corresponding to a phase and comprising at least two switches, characterized in that the control circuit is able to control the switch in a second mode in which the conduction phases of the switch have a duration of gold one-third of the signal period.

2. Rotating machine according to claim 1, characterized in that the control circuit comprises selection means for selectively activating the first mode or the second mode.

3. Rotating machine according to claim 2, characterized in that the selection means are adapted to activate the first mode or the second mode according to a speed information of rotation of the machine.

4. Rotating machine according to claim 3, characterized in that the selection means are adapted to activate the second mode when said speed information indicates a rotational speed lower than a first threshold.

5. Rotating machine according to one of claims 1 to 4, characterized in that the selection means are adapted to activate the first mode or the second mode depending on a voltage of a battery supplying the machine.

6. Rotating machine according to claim 5, characterized in that the selection means are adapted to activate the second mode when the voltage of the battery is less than a second threshold.

7. Rotating machine according to one of claims 1 to 6, characterized in that the control circuit comprises means for generating, in the second mode, a control signal for the switch formed at least on the basis of a combination of the signal delivered by the first sensor and a signal delivered by a second sensor.

8. Rotating machine according to claim 7, characterized in that said means for generating the control signal comprise a first logic circuit capable of performing an exclusive-OR operation between the signal delivered by the first sensor and the signal delivered by the second. sensor.

9. Rotating machine according to claim 8, characterized in that said means for generating the control signal comprise a second logic circuit capable of performing a logical AND operation between the signal delivered by the first sensor and the result of the logic operation of or exclusive.

10. Rotating machine according to claim 8 or 9, characterized in that said means for generating the control signal comprise means for advancing by 30 ° the phase of the signals applied to the first logic circuit.