Electrical assembly comprising a rotary electric machine

Abstract

The invention relates to an electrical assembly (100) comprising: - a rotary electric machine (1) comprising a plurality of phase coils (2); - a motor control circuit (3) comprising a plurality of switching arms (4) mounted in parallel; - a phase-current-measuring unit (8) comprising a current-measuring resistor (9) for measuring the current flowing in only one of the phase coils (2); - a control unit (15) for controlling the rotation of the rotary electric machine (1), the current-measuring resistor (9) being placed in series on one of the switching arms (4) in order to allow the current passing therethrough to be measured, and the control unit (15) being arranged to control the rotation of the rotary electric machine (1) using the measurement of the current passing through the switching arm (4).

Description

Electrical assembly comprising a rotating electrical machine Scope of the invention

[0001] The field of the invention is that of electrical assemblies comprising a rotating electrical machine. State of the art

[0002] In a rotating electrical machine comprising phase coils, the coils, when energized, cause the rotating machine to rotate. However, for the rotating machine to rotate continuously, a control circuit may need to energize one or more coils (but not all) at a time, energize the coils in a particular order, energize the coils forward and backward at different times, etc.

[0003] Controlling a rotating electrical machine of this type therefore requires the use of specialized circuits creating control signals specific to each of the phase coils of the rotating electrical machine.

[0004] Controlling the rotating electrical machine also requires monitoring the angular position of the machine's rotor in order to synchronize the phase control signals with the machine's rotation.

[0005] A classic method for tracking the angular position of a common electrical machine is by measuring the phase current, in particular by measuring the current flowing through at least one of the phase coils.

[0006] We know from patent WO2004062079 a method of angular tracking of the rotating electrical machine by the use of a current measuring resistor (or "shunt" resistor) at the junction of the three phase arms of the control circuit.

[0007] The drawback of this method is that the measured current is the sum of the currents flowing through the phases. It is therefore necessary to calculate the current flowing through only one phase by taking several current measurements at different angles of rotation of the rotating electrical machine.

[0008] This method is therefore computationally intensive and requires complex implementation.

[0009] The invention aims to resolve all or part of these drawbacks.

[0010] The invention relates to an electrical assembly comprising: a rotating electrical machine having a plurality of phase coils, a motor control circuit comprising a plurality of switching arms mounted in parallel, each arm comprising an up-side switch and a down-side switch connected to each other at a midpoint, each midpoint being intended to be connected to a phase of the rotating electrical machine, a phase current measuring unit, comprising a current measuring resistor (or "shunt resistor") and arranged to measure the current flowing in only one of the phase coils of the rotating electrical machine, a control unit electrically connected to the phase current measuring unit and to the motor control circuit,and arranged to control the up and down switches of the switching arms of the control circuit to control the rotation of the rotating electrical machine, the current-measuring resistor being placed in series on one of the switching arms and arranged to allow the measurement of the current through the switching arm by the phase current measuring unit, and the control unit being arranged to control the rotation of the rotating electrical machine using the measurement of the current through the switching arm.

[0011] According to one aspect of the invention, the electrical assembly comprises a power supply, electrically connected to the motor control circuit and arranged to power the rotating electrical machine,

[0012] According to one aspect of the invention, the power source is a DC voltage source.

[0013] According to one aspect of the invention, the power source is, for example, a battery, in particular a vehicle battery.

[0014] According to one aspect of the invention, the rotating electrical machine comprises three phase coils.

[0015] According to one aspect of the invention, the control circuit comprises three switching arms, each switching arm being electrically connected to one phase of the rotating electrical machine.

[0016] According to one aspect of the invention, one of the switching arms of the control circuit is a measuring arm, and is electrically connected to a phase of the rotating electrical machine called the measuring phase.

[0017] According to one aspect of the invention, the current measuring resistor is placed on the measuring arm of the control circuit, and is traversed by the phase current Ip passing through the measuring phase of the rotating electrical machine.

[0018] According to one aspect of the invention, no current measuring unit is placed in series with the other phase coils, in particular no phase current measuring resistor measures the current through the other coils.

[0019] According to one aspect of the invention, the control unit receives only the measured current Ip from one of the phases, and the control of the control circuit by the control unit does not use measurement of the current from the other two phases.

[0020] According to one aspect of the invention, the three switches on the lower side are each connected to one of the three phases and to the ground of the electrical assembly, and the three switches on the upper side are each connected to one of the three phases and to a positive terminal of the power supply.

[0021] According to one aspect of the invention, the control unit is arranged to control the up side switches and down side switches of the control circuit switching arms to create control signals for each of the phase coils of the rotating electrical machine.

[0022] According to one aspect of the invention, the control signals generated by the control unit allow separate control of the excitation currents passing through the phase coils of the rotating electrical machine.

[0023] According to one aspect of the invention, the control signals of the rotating electrical machine are pulse-width modulated ("PWM") signals. As the PWM activation time increases from zero to one hundred percent, the voltage across the phases of the rotating electrical machine increases proportionally from zero to its maximum value.

[0024] According to one aspect of the invention, the control unit can control the amount of current supplied to each phase of the rotating electrical machine by changing the pulse width of the control signals.

[0025] According to one aspect of the invention, the control signals of the rotating electrical machine are periodic signals, these signals being arranged so as to generate sinusoidal currents in the phases of the rotating electrical machine.

[0026] According to one aspect of the invention, the control signals of the rotating electrical machine are arranged so as to create a periodic and sinusoidal potential difference between each of the phases of the rotating electrical machine.

[0027] According to one aspect of the invention, the control unit is arranged to generate control signals in such a way as to achieve sinusoidal switching.

[0028] According to one aspect of the invention, the currents passing through the phases of the rotating electrical machine are sinusoidal signals of the same frequency f, of zero average value and of amplitude 2*Imax, each signal being phase-shifted by 120° with respect to the other two signals.

[0029] According to one aspect of the invention, the control signals are periodic signals of the same frequency, in particular of frequency f equal to the frequency of the currents passing through the phases of the rotating electrical machine, and each control signal is phase-shifted by 120° with respect to the other two control signals.

[0030] According to one aspect of the invention, the current measuring unit is arranged to transfer to the control unit the value of the current passing through the measuring phase of the rotating electrical machine.

[0031] According to one aspect of the invention, the control unit is arranged to detect zero crossings of the current through the measuring phase of the rotating electrical machine.

[0032] Specifically, the control unit is arranged to measure the time between two zero crossings of the current through the measurement phase of the rotating electrical machine.

[0033] According to one aspect of the invention, the control unit is arranged to measure the phase shift φ between the control signals and the current through the measurement phase of the rotating electrical machine from the detection of the zero crossing of the current through the measurement phase of the rotating electrical machine.

[0034] According to one aspect of the invention, the control unit is arranged to generate the control signals in such a way as to control the phase shift φ between the control signals and the current through the measurement phase of the rotating electrical machine.

[0035] According to one aspect of the invention, the control unit is arranged to regulate the phase shift φ in order to control the torque exerted by the rotating electrical machine, in particular in order to maximize the torque exerted by the rotating electrical machine.

[0036] According to one aspect of the invention, the control unit is arranged to measure the maximum current Imax through the measuring phase of the rotating electrical machine.

[0037] Advantageously, the invention makes it possible to measure the current through the measurement phase by only taking one measurement per period of rotation of the rotating electrical machine.

[0038] Advantageously, the invention makes it possible to improve the accuracy of phase current measurement.

[0039] Advantageously, the invention makes it possible to reduce the computing power required to obtain a phase current, because it can be measured directly.

[0040] The invention also relates to a method for controlling a rotating electrical machine comprising a plurality of phase coils, using a motor control circuit comprising a plurality of switching arms mounted in parallel, each arm comprising an upper-side switch and a lower-side switch connected to each other at a midpoint, each midpoint being intended to be connected to a phase of the rotating electrical machine, the method comprising the following steps: measuring, using a current-measuring resistor (or "shunt resistor"), a phase current flowing in one of the phase coils of the rotating electrical machine, the current-measuring resistor being placed in series on one of the switching arms, called the measuring arm, and arranged to allow the measurement of the current flowing through the switching arm.To control the upper and lower side switches of the control circuit's switching arms to control the rotation of the rotating electrical machine, in order to control the rotation of the rotating electrical machine using the measurement of the current flowing through the measuring arm.

[0041] According to one aspect of the invention, the control method includes a step of transferring from the current measuring unit to the control unit the value of the current passing through the measuring phase of the rotating electrical machine.

[0042] According to one aspect of the invention, the control method includes a step of detection by the control unit of the zero crossings of the current passing through the measurement phase of the rotating electrical machine.

[0043] According to one aspect of the invention, the control method includes a step of measuring the time between two zero crossings of the current passing through the measurement phase of the rotating electrical machine.

[0044] According to one aspect of the invention, the control method includes a step of measuring the phase shift φ between the control signals and the current through the measurement phase of the rotating electrical machine from the detection of the zero crossing of the current through the measurement phase of the rotating electrical machine.

[0045] According to one aspect of the invention, the control method includes a step of generating control signals so as to control the phase shift φ between the control signals and the current through the measurement phase of the rotating electrical machine.

[0046] According to one aspect of the invention, the control method includes a phase shift control step by the control unit so as to control the torque exerted by the rotating electrical machine, in particular so as to maximize the torque exerted by the rotating electrical machine.

[0047] According to one aspect of the invention, the control method includes a measurement step by the control unit of the maximum current Imax passing through the measurement phase of the rotating electrical machine. List of figures

[0048] Other features, details and advantages of the invention will become clearer upon reading the following description on the one hand, and several illustrative and non-limiting examples of embodiments given with reference to the attached schematic drawings on the other hand, in which:

[0049] This is a representation of an electrical assembly comprising a rotating electrical machine as known in the state of the art.

[0050] Laest is a representation of an electrical assembly comprising a rotating electrical machine according to an embodiment of the invention.

[0051] Laest is a time-domain representation of the control signals of the phase coils of the rotating electrical machine, the potential differences between each of the coils of the rotating electrical machine, and the phase current Ip flowing through the measurement phase of the rotating electrical machine.

[0052] The features, variations, and different embodiments of the invention can be combined in various ways, provided they are not incompatible or mutually exclusive. In particular, variations of the invention may include only a selection of features, described hereafter in isolation from the other features described, if this selection of features is sufficient to confer a technical advantage and / or to differentiate the invention from prior art. Detailed description

[0053] We have represented on the electrical assembly 100 comprising a rotating electrical machine 1 as known in the state of the art.

[0054] The electrical assembly 100 comprises: a rotating electrical machine 1 having a plurality of phase coils 2 designated respectively U, V and W, a motor control circuit 3 comprising a plurality of switching arms 4 mounted in parallel, each arm comprising an upper side switch 5 and a lower side switch 6 connected to each other at a midpoint, each midpoint 7 being intended to be connected to a phase 2 of the rotating electrical machine, a phase current measuring unit 8, comprising a current measuring resistor 9 (or "shunt resistor") and arranged to measure the current flowing in only one of the phase coils 2 of the rotating electrical machine 1, a control unit 15 electrically connected to the phase current measuring unit 8 and to the motor control circuit 3,and arranged to control the upper side switches 5 and lower side switches 6 of the switching arms 4 of the motor control circuit 3 to control the rotation of the rotating electrical machine 1.,

[0055] In this embodiment, the angular tracking of the rotating electrical machine 1 is obtained by using a current measuring resistor 9 (or "shunt" resistor) at the junction of the three switching arms 4 of the control circuit 3.

[0056] The disadvantage of this method is that the measured current is the sum of the currents passing through the phases 2. It is therefore necessary to calculate the current passing through only one of the phases by making several current measurements at different angles of rotation of the rotating electrical machine 1.

[0057] This method is therefore computationally intensive and requires complex implementation.

[0058] We have represented on the, an electrical assembly 100 comprising a rotating electrical machine according to an embodiment of the invention.

[0059] The electrical assembly 100 includes a rotating electrical machine 1 comprising a plurality of phase coils 2, here three phase coils U, V and W.

[0060] The electrical assembly 100 includes a motor control circuit 3 comprising a plurality of switching arms 4 mounted in parallel, each arm comprising an upper side switch 5 and a lower side switch 6 connected to each other at a midpoint 7, each midpoint 7 being intended to be connected to a phase 2 of the rotating electrical machine 1.

[0061] The electrical assembly 100 includes a power supply 20, electrically connected to the motor control circuit 3 and arranged to supply the rotating electrical machine 1.

[0062] The power source 20 is a DC voltage source, for example a battery, in particular a vehicle battery.

[0063] The three bottom-side switches 6 are each connected to one of the three phases 2 and to the ground of the electrical assembly 100, and the three top-side switches 5 are each connected to one of the three phases 2 and to a positive terminal of the power supply 20.

[0064] The control circuit 3 comprises three switching arms 4, each switching arm being electrically connected to one phase of the rotating electrical machine.

[0065] One of the switching arms 4 of the control circuit 3 is a measuring arm 10, and is electrically connected to a phase of the rotating electrical machine named measuring phase 11, here phase U.

[0066] The control circuit 3 includes a phase current measuring unit 8, comprising a current measuring resistor 9 (or "shunt resistor") and arranged to measure the current flowing in only one of the phase coils 2 of the rotating electrical machine 1, in particular the current flowing in the measuring phase 11.

[0067] The current measuring resistor 9 is placed in series on one of the switching arms 4, in particular on the measuring arm 10. It is traversed by the phase current Ip through the measuring phase 11 of the rotating electrical machine 1, and is arranged to allow the measurement of the current through the measuring arm 10 by the phase current measuring unit 8.

[0068] No current measuring unit is placed in series with the other phase 2 coils, in particular no phase current measuring resistor measures the current through the other coils.

[0069] The electrical assembly 100 includes a control unit 15 electrically connected to the phase current measuring unit 8 and to the motor control circuit 3, and arranged to control the top side switches 5 and bottom side switches 6 of the switching arms 4 of the control circuit to control the rotation of the rotating electrical machine 1.

[0070] The phase current measuring unit 8 is arranged to transfer to the control unit 15 the value of the current through the measuring phase 11 of the rotating electrical machine 1.

[0071] The control unit 15 is arranged to control the rotation of the rotating electrical machine 1 using the measurement of the current through the measuring arm 10. The control unit 15 receives only the measured current Ip from one of the phases 2, and the control of the control circuit by the control unit does not use a measurement of the current from the other two phases 2.

[0072] The control unit 15 is arranged to control the high side switches 5 and low side switches 6 of the switching arms 4 of the control circuit 3 to create control signals for each of the phase coils 2 of the rotating electrical machine 1. These control signals generated by the control unit 15 allow separate control of the excitation currents through the phase coils 2 of the rotating electrical machine 1.

[0073] These control signals are symbolized by lines 17 in figures 1 and 2

[0074] The control unit 15 is arranged to detect the zero crossings of the current through the measuring phase 11 of the rotating electrical machine 1, in particular, to measure the time between two zero crossings of the current through the measuring phase of the rotating electrical machine 1 and to measure the phase shift φ between the control signals and the current through the measuring phase of the rotating electrical machine 1 from the detection of the zero crossing of the current through the measuring phase 11 of the rotating electrical machine 1.

[0075] The control unit 15 is arranged to generate the control signals in such a way as to control the phase shift φ between the control signals and the current through the measurement phase of the rotating electrical machine in order to control the torque exerted by the rotating electrical machine 1, in particular in such a way as to maximize the torque exerted by the rotating electrical machine 1.

[0076] The control unit 15 is also arranged to measure the maximum current Imax through the measuring phase 11 of the rotating electrical machine.

[0077] We have represented on the control signals of the phase 2 coils of the rotating electrical machine 1, the potential differences between each of the phase 2 coils of the rotating electrical machine, and the phase current Ip through the measurement phase 11 of the rotating electrical machine 1.

[0078] The control signals for the rotating electrical machine are pulse-width modulated (PWM) signals. As the PWM activation time increases from zero to one hundred percent, the voltage across the two phases of the rotating electrical machine increases proportionally from zero to its maximum value. The control unit 15 can thus control the amount of current supplied to each phase 2 of the rotating electrical machine 1 by changing the pulse width of the control signals.

[0079] The control signals of the rotating electrical machine 1 are represented by the curves U, V and W. These are periodic signals of the same frequency, in particular of frequency f equal to the frequency of the currents passing through the phases 2 of the rotating electrical machine, and each control signal is phase-shifted by 120° with respect to the other two control signals.

[0080] The control signals are arranged to generate sinusoidal currents in the phases of the rotating electrical machine.

[0081] The control signals of the rotating electrical machine are arranged to create a periodic and sinusoidal potential difference UV, VW, WU between each of the phases of the rotating electrical machine.

[0082] The control unit 15 is arranged to generate control signals in such a way as to achieve sinusoidal switching.

[0083] The currents flowing through the phases of the rotating electrical machine are sinusoidal signals of the same frequency f, with a zero average value and an amplitude of 2*Imax, each signal being phase-shifted by 120° relative to the other two signals. Only the phase current Ip flowing through the measurement phase U is shown here.

[0084] Advantageously, the invention makes it possible to measure the current through the measurement phase by only taking one measurement per period of rotation of the rotating electrical machine.

[0085] Advantageously, the invention makes it possible to improve the accuracy of phase current measurement.

[0086] Advantageously, the invention makes it possible to reduce the computing power required to obtain a phase current, because it can be measured directly.

Claims

Electrical assembly (100) comprising: a rotating electrical machine (1) having a plurality of phase coils (2), a motor control circuit (3) having a plurality of switching arms (4) mounted in parallel, each arm having an up side switch (5) and a down side switch (6) connected to each other at a midpoint (7), each midpoint (7) being intended to be connected to a phase (2) of the rotating electrical machine (1), a phase current measuring unit (8), having a current measuring resistor (9) (or "shunt resistor") and arranged to measure the current flowing in only one of the phase coils (2) of the rotating electrical machine (1), a control unit (15) electrically connected to the phase current measuring unit (8) and to the motor control circuit (3),and arranged to control the up side switches (5) and down side switches (6) of the switching arms (4) of the control circuit (3) to control the rotation of the rotating electrical machine (1), the current measuring resistor (9) being placed in series on one of the switching arms (4) and arranged to allow the measurement of the current through the switching arm (4) by the phase current measuring unit (8), and the control unit (15) being arranged to control the rotation of the rotating electrical machine (1) using the measurement of the current through the switching arm (4). Electrical assembly (100) according to claim 1, comprising a power supply (20) electrically connected to the motor control circuit (3) and arranged to supply the rotating electrical machine.(1). Electrical assembly (100) according to any one of the preceding claims, wherein one of the switching arms of the control circuit is a measuring arm (10), and is electrically connected to a phase (2) of the rotating electrical machine (1) called measuring phase (11). Electrical assembly (100) according to claim 3, wherein the current measuring resistance (9) is placed on the measuring arm (10) of the control circuit (3), and is traversed by the phase current Ip passing through the measuring phase (11) of the rotating electrical machine (1). Electrical assembly (100) according to any one of the preceding claims, wherein the control unit (15) is arranged to control the high side switches (5) and low side switches (6) of the switching arms of the control circuit (3) to create control signals for each of the phase coils (2) of the rotating electrical machine. Electrical assembly (100) according to claim 5, wherein the control signals of the rotating electrical machine (1) are pulse width modulated ("PWM") signals. Electrical assembly (100) according to any one of claims 6 to 7, wherein the control signals of the rotating electrical machine (1) are periodic signals, these signals being arranged so as to generate sinusoidal currents in the phases (2) of the rotating electrical machine (1). Electrical assembly (100) according to any one of the preceding claims, wherein the currents through the phases (2) of the rotating electrical machine (1) are sinusoidal signals of the same frequency f, of zero average value and of amplitude 2*Imax, each signal being phase-shifted by 120° with respect to the other two signals. Electrical assembly (100) according to any one of the preceding claims, wherein the control unit (15) is arranged to detect zero crossings of the current through the measuring phase (11) of the rotating electrical machine (1). Electrical assembly (100) according to claim 9, wherein the control unit (15) is arranged to measure the time between two zero crossings of the current through the measuring phase (11) of the rotating electrical machine (1). Electrical assembly (100) according to any one of claims 9 to 10, wherein the control unit (15) is arranged to measure the phase shift φ between the control signals and the current through the measurement phase (11) of the rotating electrical machine (1) from the detection of the zero crossing of the current through the measurement phase (11) of the rotating electrical machine (1). Electrical assembly (100) according to claim 11, wherein the control unit (15) is arranged to generate the control signals so as to control the phase shift φ between the control signals and the current through the measuring phase of the rotating electrical machine. Electrical assembly (100) according to claim 12, wherein the control unit (15) is arranged to regulate the phase shift φ so as to control the torque exerted by the rotating electrical machine (1), in particular so as to maximize the torque exerted by the rotating electrical machine (1). Electrical assembly (100) according to any one of the preceding claims, wherein the control unit (15) is arranged to measure the maximum current Imax through the measuring phase (11) of the rotating electrical machine (1). A method for controlling a rotating electrical machine (1) comprising a plurality of phase coils (2), using a motor control circuit (3) comprising a plurality of switching arms (4) mounted in parallel, each arm comprising an upper-side switch (5) and a lower-side switch (6) connected to each other at a midpoint (7), each midpoint being intended to be connected to a phase (2) of the rotating electrical machine (1), the method comprising the following steps: measuring, using a current-measuring resistor (9) (or "shunt resistor"), a phase current flowing in one of the phase coils (2) of the rotating electrical machine (1), the current-measuring resistor (9) being placed in series with one of the switching arms (4) designated as the measuring arm (10) and arranged to allow the measurement of the current flowing through the switching arm,to control the upper side switches (5) and lower side switches (6) of the switching arms (4) of the control circuit to control the rotation of the rotating electrical machine, in order to control the rotation of the rotating electrical machine using the measurement of the current flowing through the measuring arm (10).

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