FR3136129A1 - Device for powering a synchronous motor from a DC power source - Google Patents

Abstract

TITLE IN APPBODY-TITLE One aspect of the invention relates to a power supply device for a synchronous motor comprising a control unit (U1) for controlling transistors of a Sine Voltage inverter converter (1) comprising an inductor ( Li) connected between a first and second node of a transistor arm of the converter. The control unit (U1) is configured to, in a start-up mode: evaluate at start-up for each phase output, an average value of direct phase current IPi transmitted to each phase of the synchronous machine as a function at least of the signal representative of the unidirectional variable direct current of inductance ILi passing through the corresponding inductance, adapt the control of the transistors (Si, Si', Ri, Ri') according to a received instruction and the average value of direct phase current IPi evaluated according to a switching period Tsi and a duty cycle of the inductance αci. Figure to be published with the abstract: Figure 2

Description

Device for powering a synchronous motor from a DC power source TECHNICAL FIELD OF THE INVENTION

The technical field of the invention is that of powering a synchronous motor having a nominal power of several Kilowatts from a continuous source, in particular during a starting mode comprising a starting condition of zero speed or close to zero at a predetermined speed or in locked rotor condition, with a starting torque imposed on the synchronous motor.

The present invention relates to an assembly comprising a synchronous motor and a synchronous motor power supply device as well as a method for managing the starting of a synchronous motor.

TECHNOLOGICAL BACKGROUND OF THE INVENTION

The synchronous motor comprising a rotor with permanent magnets is known. The synchronous motor also comprises a stator comprising coils capable of generating a magnetic field as a function of the current received forming for example three phases comprising phase outputs each connected to a conversion circuit to provide an electrical supply having an alternating voltage in the coils . The synchronous motor has the particularity of having its speed dependent on the frequency of its alternating power supply.

When the source is of the DC type, that is to say it delivers a DC voltage, for example from a battery, the conversion circuit requires converting this DC voltage into a sinusoidal AC voltage.

There schematically represents three phases P1, P2, P3 mounted in star of a synchronous motor, represented schematically by a resistor R1, R2, R3 and a coil L1, L2, L3 and a conventional converter 1 for converting a direct voltage Vs of a DC source into a chopped alternating voltage u, v, w via six transistors Q1, Q2, Q3, Q4, Q5, Q6, forming a chopped ripple, or two transistors per phase. The conventional converter is, as its name suggests, the best-known solution. Such a synchronous motor control system further comprises a control unit for transistors Q1, Q2, Q3, Q4, Q5, Q6. To allow controlled rotation of the rotor of the synchronous motor, the current circulating in the stator coils must be controlled precisely by the control unit controlling the transistors Q1, Q2, Q3, Q4, Q5, Q6 as a function of the position of the rotor relative to the stator. To determine the position of the rotor, several solutions are known from the prior art. Furthermore, in a starting condition requiring a high torque, or even in the event of a blocked rotor, it is necessary to determine the value of the current transmitted to the phases of the machine for safety reasons, in particular to activate protection of the electronics of the converter or protect the rotor winding or avoid mechanical breakage at the rotor shaft. Also, conventional converters are thermally stressed in the locked rotor condition, leading to additional costs.

In addition, as the windings forming the phases of the stator of a synchronous motor generally have low resistance, the voltage to be applied must be of low value to produce sufficient current amplitudes. However, a conventional inverter is not able to lower the instantaneous output voltage to maintain a constant torque in the machine in start-up mode since it only applies the DC voltage of the input network with a certain ratio cyclic. To lower the voltage, one solution is to add a DC/DC converter upstream to lower the DC input voltage of the conventional converter but this greatly increases the number of components and therefore the losses and the risk of fault; this also complicates the control of the two converters.

Sine Voltage inverter converters are also known, hereinafter called SdT, having the characteristic of producing for each phase an output signal of sinusoidal shape with a residual ripple typically of 2%, also called in English "ripple" forming a so-called “smoother” sinusoidal signal compared to conventional converters. By 2% residual ripple we mean that the voltage amplitude of the residual ripple superimposed on the sinusoidal signal of the sine voltage is less than 2% of the amplitude of the sinusoidal signal of the sine voltage. The SdT inverter converter forms, for each phase in start-up mode, a DC/DC converter and has the advantage, unlike the conventional converter, of being able to lower its instantaneous output voltages for each phase output to the desired amplitudes to allow the establishment only a constant direct current in each phase of the stator. Indeed, for each phase the converter acts as a DC/DC converter which can therefore lower the output voltage compared to the input voltage. These SdT inverter converters are controlled by a control unit which controls both the value of the DC direct current (in start-up mode: start-up condition or locked rotor condition), and in normal operating mode, the frequency and the amplitude of a sinusoidal alternating current supplying each phase of the motor. The control unit requires current value feedback from current sensors at the phase levels.

The SdT inverter converter has the advantage of being able to lower its instantaneous output voltages (quasi-continuous smooth voltages) to the desired amplitudes to allow the establishment of only a DC current in the synchronous motor in starting mode, while maintaining a constant torque to the rotor. Indeed, the SdT inverter converter can form a DC/DC converter for each phase which can therefore lower the output voltage compared to the input voltage. A multi-objective digital control law ensures current regulation while minimizing phase voltages in start-up mode. The direct voltages applied to the phases of the machine induce a current on the motor phase which must be measured to allow current regulation.

Thus the SdT inverter converter has the advantage of making it possible to control the power supply of a synchronous motor coupled to a load involving a significant starting torque or likely to cause the rotor to lock but requires knowing the value of the current in each phase of the synchronous motor to control it.

Different types of current sensors exist to measure the current in each phase but each type of sensor has at least one major drawback, such that it is not conceivable to use it alone to measure the phase current. For example, a major disadvantage of several types of sensors is that they do not cover the entire operating range of a synchronous motor from starting mode (at constant continuous phase current in locked rotor condition or in starting condition up to a predetermined rotor speed with starting torque) to a normal AC mode with high frequency when the rotor is at a speed higher than the predetermined speed of the end of the starting mode. Another major disadvantage of certain known sensors is to produce heating (joule losses) unacceptable for the environment of the other components and/or the efficiency.

In particular, current sensors by resistive effect (current shunt) have the disadvantage of inducing significant heating which can lead to an increase in temperature on other electronic components and reduce efficiency by producing joule losses.

Current measurement sensors by Hall effect (hall effect sensor), by Neel effect (Neel effect sensor), or by magneto-resistive effect (MR sensor) are only applicable for frequencies below MHz and therefore do not cover not the entire operating range of the engine; They also have the disadvantage of being sensitive to external magnetic fields and high temperatures. Sensors with measurement by Rogowski effect (Rogowski probe) or sensors using current transformers (called TI sensor) do not make it possible to measure DC current at very low frequencies (<1Hz) and therefore do not cover the entire range of engine operation. Current transformer sensors (called TI sensors) have the advantage of being robust and inexpensive. However, in starting mode in the event of resistant torque in starting condition or in the case of too high a torque in locked rotor condition, these current transformer sensors do not make it possible to measure the current transmitted to the phases which is a current constant DC in a locked rotor condition or in a start-up condition by an SDT converter.

A solution would therefore be to use different types of current sensors per phase depending on the rotor speed (voltage frequency) but this would entail a very high cost and a higher risk of breakdown (increase in the number of components of different types) . For example, for each phase output, installing a Hall effect current measurement sensor mounted on a phase output line and configured to measure the low frequency phase output current and a TI sensor mounted on the same phase output line to measure the current of the high frequency phase output, would cause additional cost and a higher risk of failure.

The invention aims to remedy these various drawbacks by proposing a new power supply device and a new method for managing the start of a permanent magnet synchronous motor in an aircraft capable of having frequencies beyond MHz while allowing starting with a constant torque, efficient and reliable starting, without requiring the addition of different types of sensors at each phase to reduce the risk of faults.

The invention offers a solution to the problems mentioned above, by making it possible to power a synchronous motor with an intensity sensor of the Ti current transformer type at each phase of the synchronous motor.

• un convertisseur onduleur à Sinus de Tension de type Buck-boost comprenant :
  • deux entrées de tension continue chacune destinée à être reliée à une source d'alimentation en courant continu,
  • un nombre N de sorties de phase formant un système multi-phasé, destinées chacune à être reliée à une connexion de phase correspondante du moteur synchrone,
• et pour chaque sortie de phase :
  • un bloc élévateur comprenant un bras élévateur relié à la sortie de phase correspondante, le bras élévateur comprenant deux transistors reliés ensemble à un premier nœud,
  • un bloc abaisseur comprenant deux transistors reliés ensemble à un deuxième nœud et entre les deux entrées de tension continue,
  • une inductance connectée entre lesdits premier et deuxième nœuds, pour transmettre un courant I_Lidu bloc abaisseur au bloc élévateur de la sortie de phase correspondante, et
• caractérisé en ce qu’il comprend en outre une unité de commande des transistors dudit convertisseur onduleur pour commander l’alimentation électrique de chaque phase du moteur synchrone, l’unité de commande étant configurée pour, dans un mode de démarrage
  pour chaque phase :
  • évaluer, une valeur moyenne de courant continu de phase IPi circulant dans la phase correspondante de la machine synchrone, en fonction au moins d’un signal représentatif du courant continu variable unidirectionnel d’inductance I_Litransmettant un courant au bloc élévateur de la sortie de phase correspondante
  • adapter la commande des transistors du bloc abaisseur et élévateur, en fonction de la valeur moyenne de courant continu de phase IPi évaluée selon une période de découpage Tsi et un rapport cyclique de charge de l’inductance αci.

One aspect of the invention relates to a power supply device for a synchronous motor comprising:

• a Buck-boost type voltage sine inverter converter comprising:
  • two DC voltage inputs each intended to be connected to a DC power source,
  • a number N of phase outputs forming a multi-phase system, each intended to be connected to a corresponding phase connection of the synchronous motor,
• and for each phase output:
  • a step-up block comprising a step-up arm connected to the corresponding phase output, the step-up arm comprising two transistors connected together to a first node,
  • a step-down block comprising two transistors connected together to a second node and between the two direct voltage inputs,
  • an inductor connected between said first and second nodes, to transmit a current I _Li from the step-down block to the step-up block of the corresponding phase output, and
• characterized in that it further comprises a control unit for the transistors of said inverter converter to control the electrical supply of each phase of the synchronous motor, the control unit being configured to, in a start mode
  for each phase:
  • evaluate, an average value of phase direct current IPi circulating in the corresponding phase of the synchronous machine, as a function of at least one signal representative of the unidirectional variable direct current of inductance I _Li transmitting a current to the step-up block of the output of corresponding phase
  • adapt the control of the transistors of the step-down and step-up block, as a function of the average value of phase direct current IPi evaluated according to a switching period Tsi and a cyclic charge ratio of the inductance αci.

Thanks to the invention, information from the signal representative of the unidirectional variable direct current of inductance I _Li is used to evaluate the average value of constant phase direct current IPi transmitted in each phase in starting mode (starting or locked rotor condition ). Indeed, for each phase, from the current passing through the inductance of the converter over a switching period Tsi of supplying the inductor, during a starting mode, we can deduce the value of the average current circulating in a phase of the corresponding machine. When the motor is in the locked rotor condition or at the start of a starting condition, the rotor being stopped, no EMF on the phases is generated by the rotor which is stationary, the current circulating in each inductor during a switching period Tsi, has an average value identical to the value of the average direct phase current transmitted to the windings by each phase output. The power supply device can therefore estimate the average value of the direct phase current from information from the signal representative of the unidirectional variable direct current of inductance I _{Li .} .

This avoids having a phase current sensor for each phase of the synchronous motor used only in starting mode (up to a predetermined speed). For example, the device can have one and the same type of phase current sensor TI per phase used only in normal mode (after the predetermined speed) which makes it possible to transmit a signal representative of the phase current, to the control unit only in this normal operating mode, engine or alternator.

For example, the power supply device can calculate an average value of the inductance current corresponding to the average value of the phase current from the phase output and input voltage value, the switching period Tsi, the duty cycle of the inductor αci or/and through an inductor current sensor measuring the current in the inductor during start-up mode. The control unit can then carry out current regulation to obtain constant torque starting since once the speed is established at the equilibrium point, the motor can be modeled by a simple network of resistors (in star or triangle configuration depending on the machine winding connection diagram).

In addition, using an SdT inverter converter makes it possible to reduce or eliminate thermal constraints in the condition of a locked rotor unlike conventional converters. Indeed, the locked rotor generally strongly limits the thermal performance of conventional inverters, producing heating of the various electronic components. The advantage of an SdT converter is to have minimal losses in the locked rotor condition, thanks in particular to at least one inductance between the step-down block and the step-up block.

In addition, the use of an SdT type inverter converter makes it possible to have a smoother sinusoidal voltage at the phase output than that of a conventional converter and thus to reduce the high frequency iron and copper losses in the synchronous machine compared to to this same machine powered by a conventional converter.

Such a synchronous machine of several kilowatts can thus start with a load presenting a torque at start-up or in a locked rotor condition. The synchronous machine can be used in different fields, and in particular in a pump, ventilation, gear system, etc.

In addition to the characteristics which have just been mentioned in the previous paragraph, a power supply device according to the invention may have one or more complementary characteristics among those described in the following paragraphs, considered individually or in all technically possible combinations:

• à chaque sortie de phase pour mesurer la tension de sortie Voi et
• à l’entrée positive pour mesurer la tension d’entrée positive Ve d’une source de tension continue,
• et l’unité de commande comprend une mémoire dans lequel une valeur de l’inductance li est mémorisée pour chaque phase et l’unité de commande est configurée pour calculer la valeur moyenne de courant continu de phase IPi selon la formule: IPi= .

According to a first embodiment, the control unit is connected:

• at each phase output to measure the output voltage Voi and
• at the positive input to measure the positive input voltage Ve of a direct voltage source,
• and the control unit comprises a memory in which a value of the inductance li is stored for each phase and the control unit is configured to calculate the average phase direct current value IPi according to the formula: IPi= .

This first embodiment makes it possible to do without a current sensor in the inductance line.

According to a second embodiment, the converter further comprises an inductance current sensor by inductance measuring a signal representative of the inductance current I _Li circulating in the corresponding inductance towards the corresponding step-up block, the current sensor of inductor being connected to the control unit to transmit information on the inductance current I _Li to evaluate the average value of direct phase current IPi.

This second embodiment makes it possible to use an inductance current sensor in the converter to measure an inductance current (unidirectional variable current) transmitted to the corresponding step-up block and the control unit can thus receive each signal representative of the unidirectional variable direct current of inductor passing through the inductor to deduce each average phase current (constant direct current) in start-up mode

Advantageously, the inductance current sensor is of the TI current transformer type. We benefit from a simple and robust sensor, suitable for measuring the current circulating in the inductance during the start-up phase, which is a unidirectional variable direct current, and not a constant direct current like that obtained at the output of each phase.

According to another example of this second embodiment, the inductance current sensor is of the hall effect type.

According to a first example, of this embodiment the control unit comprises a block for transforming the signal representative of the inductance current into an average value of the signal representative of the inductance current I _Li , into an average value of the signal representative of the inductance current I _{L i ,} the average value of direct phase current IPi being equal to the average value of the signal representative of the inductance current I _Li . This avoids having to have computing power to evaluate the average value of direct phase current IPi. The transformation block can for example be a low pass filter.

• mémoriser dans chaque période de découpage Tsi, le courant max i_pksignal représentatif du courant d’inductance I_{Li ,}
• calculer un rapport cyclique de décharge de l’inductance αdi correspondante αdi selon la formule et
• calculer la valeur moyenne du signal représentatif du courant d’inductance I_{Li ,}selon la formule₌ .

According to another example of this embodiment, the control unit is connected to each phase output to measure the output voltage Voi and comprises a memory in which a value li of each inductance is stored and the control unit is configured for each phase:

• memorize in each switching period Tsi, the maximum current i _pk signal representative of the inductance current I _{Li ,}
• calculate a discharge duty cycle of the corresponding inductance αdi αdi according to the formula And
• calculate the average value of the signal representative of the inductance current I _{Li ,} according to the formula ₌ .

Compared to the previous example, this allows you to avoid having a transformation block.

According to a third embodiment combinable with the first two, the power supply device comprises at least N-1 phase current sensors of the TI current transformer type, each mounted on a respective phase output to measure, in a normal mode operating mode, the current IPi in said phase output, each phase current sensor being capable of transmitting to the control unit a signal representative of the measured phase current, and in which the control unit is configured in normal operation to adapt the control of the transistors of the step-down and step-up blocks as a function of the signal representative of the measured inductance current I _Li . In particular, the control unit is configured to pass, after a start-up mode, into a normal operating mode, in which, for each phase, the control unit controls the transistors of the boost blocks and the step-down blocks as a function of each value of an alternating current measured by each TI type phase current sensor and a setpoint received.

According to an example of this third embodiment, the number of phase current sensors of the TI current transformer type is equal to the number N of phase outputs. This allows for fewer calculations in normal operating mode to determine the current in each phase.

According to another example, the number of phase current sensors of the TI current transformer type is equal to N-1, N being the number of phase outputs, one phase output line among the N being without a current sensor. phase. The control unit is then configured to use the N-1 values measured by the phase current sensors to calculate the current in the phase output line lacking a phase current sensor.

According to an example of this third embodiment which can be combined with the previous embodiments, the control unit is configured as a function of a characteristic of the control of the transistors of the raising and lowering blocks to go from a starting mode to a normal operating mode, in which the control unit controls the transistors of the step-up and step-down blocks as a function of each value of an alternating current measured by each TI type phase current sensor and a setpoint received. This feature allows switching from a start-up mode to a normal operating mode, without rotor speed sensor measurement, for example, the control unit switches from the start-up phase to the normal operating phase, after having received a voltage reference having a frequency greater than a predetermined frequency, such as 1 Hz.

According to a fourth embodiment which can be combined with the previous embodiments, each step-up block further comprises a capacitor mounted between ground and the phase output. In other words, the step-up block is mounted in parallel with the capacitor. This makes it possible to have, with the inductor, a clean sinusoidal voltage in the normal operating phase after starting.

According to a fifth embodiment which can be combined with the previous embodiments, the Sine Voltage inverter converter is arranged for mounting the phases of the synchronous motor in a star pattern.

According to a sixth embodiment which is a variant of this fifth embodiment which can be combined with the previous embodiments, the Sine Voltage inverter converter is arranged for mounting the phases of the synchronous motor in a triangle.

According to a seventh embodiment which can be combined with the previous embodiments, the Sine Voltage inverter converter comprises three phase outputs. According to one variant, the Sine Voltage inverter converter comprises six phase outputs.

According to an eighth embodiment which can be combined with the previous embodiments, the control unit is configured to control in the off state the transistors of each block (step-up and step-down) if the value of one of the maximum currents of a inductances measured during a switching period Tsi or if the average value of direct phase current IPi evaluated is greater than a threshold.

According to a ninth embodiment combinable with the previous embodiments, each step-down block comprises a driver connected to the control of the transistors of the corresponding step-down block to control them according to a signal received from the control unit.

According to a tenth embodiment, each step-up block comprises a driver connected to the control of the transistors of the corresponding step-up block to control them according to a signal received from the control unit.

Another aspect of the invention relates to an assembly comprising a device for powering a synchronous motor according to the aspect of the invention described previously with or without any of the characteristics described in the preceding paragraphs and a synchronous motor with N phases each connected to a respective phase output.

According to one embodiment, the synchronous motor comprises a rotor comprising a permanent magnet armature.

According to one embodiment, the phases of the synchronous motor are connected in a star or triangle arrangement.

• réception d’une consigne de démarrage,
• pour chaque sortie de phase :
• évaluer une valeur moyenne de courant continu de phase IPi circulant dans la phase correspondante de la machine synchrone, en fonction au moins du signal représentatif du courant continu variable unidirectionnel d’inductance ILi transmettant un courant au bloc élévateur de ladite sortie de phase,
• adapter la commande des transistors des blocs abaisseur et élévateur en fonction de la consigne et de ladite valeur moyenne de courant continu de phase IPi .

Another aspect of the invention relates to a method for managing the start-up of a synchronous motor of an assembly of the aspect of the invention described above comprising in start-up mode the steps of a closed current regulation loop:

• receipt of a start instruction,
• for each phase output:
• evaluate an average value of direct phase current IPi circulating in the corresponding phase of the synchronous machine, as a function of at least the signal representative of the unidirectional variable direct current of inductance ILi transmitting a current to the step-up block of said phase output,
• adapt the control of the transistors of the step-down and step-up blocks as a function of the setpoint and said average value of direct phase current IPi.

• une sous étape de mesure de la tension de sortie Voi, et
• une sous étape de mesure de la tension d’entrée positive V_ed’une source de tension continue,
• une sous étape de calcul de la valeur moyenne de courant continu de phase IPi selon la formule : .

According to one embodiment, the control unit includes a value li of the stored inductance and for each phase output, the evaluation step includes:

• a sub-step of measuring the output voltage Voi, and
• a sub-step of measuring the positive input voltage V _e of a direct voltage source,
• a sub-step of calculating the average value of phase direct current IPi according to the formula: .

• une sous étape de mesure d’un signal représentatif du courant d’inductance I_{L i}circulant dans chaque inductance,
• une sous étape de transformation du signal représentatif du courant d’inductance I_{L i}en une valeur moyenne du signal représentatif du courant d’inductance,
• et la valeur moyenne de courant continu de phase IPi évaluée pour chaque phase est égale à la valeur moyenne du signal représentatif du courant d’inductance.

According to another embodiment, the evaluation step comprises for each phase output:

• a sub-step of measuring a signal representative of the inductance current I _{L i} circulating in each inductance,
• a sub-step of transforming the signal representative of the inductance current I _{L i} into an average value of the signal representative of the inductance current,
• and the average phase direct current value IPi evaluated for each phase is equal to the average value of the signal representative of the inductance current.

• une sous étape de mesure d’un signal représentatif du courant d’inductance I_{L i}circulant dans l’inductance,
• une sous étape de mesure des tensions de sortie Voi, ,
• une sous étape de mémorisation dans chaque période de découpage Tsi, le courant max i_pksignal représentatif du courant d’inductance I_Li,
• une sous étape de calcul d’un rapport cyclique de décharge de l’inductance αdi correspondante selon la formule et
• une sous étape de calcul de la valeur moyenne du signal représentatif du courant d’inductance I_Liselon la formule = .

According to another embodiment, the control unit includes a value li of the stored inductance and the evaluation step includes for each phase output:

• a sub-step of measuring a signal representative of the inductance current I _{L i} circulating in the inductor,
• a sub-step of measuring the output voltages Voi, ,
• a storage sub-step in each switching period Tsi, the maximum current i _pk signal representative of the inductance current I _Li ,
• a sub-step of calculating a cyclic discharge ratio of the corresponding inductance αdi according to the formula And
• a sub-step of calculating the average value of the signal representative of the inductance current I _Li according to the formula = .

According to one embodiment, for each phase output, the control unit controls the transistors of the step-down and step-up blocks, in start-up mode, in buck/step-down mode of the converter according to a setpoint and the average phase direct current value IPi evaluated.

The invention also relates to a power supply method comprising a step of receiving a start instruction, placing it in start mode until a phase current can be measured by a phase current sensor , wherein during the startup mode, the power process performs the steps of a startup process as presented above.

According to one example, the control unit in start-up mode comprises a control of the inverter converter in discontinuous mode, driving an inductance current having a triangular signal varying between a zero value and a peak value, according to the controlled duty cycle such that the sought phase current measurement corresponds to the average value of the calculated inductance current.

According to one embodiment, the power supply method comprises a normal operating mode in which each phase current sensor transmits a signal representative of an alternating current flowing in the phase output to the control unit to control the transistors of the inverter converter according to this signal and a received instruction.

The invention and its various applications will be better understood on reading the following description and examining the accompanying figures.

BRIEF DESCRIPTION OF THE FIGURES

The figures are presented for information purposes only and in no way limit the invention.

represents an electrical diagram of a conventional converter connected to the phases of a stator of a motor.

represents an electrical principle diagram of a power supply device for a synchronous motor according to an example of a first embodiment.

represents a schematic diagram of a phase line generally of the power supply device of a synchronous motor of the .

represents an electrical diagram of a principle diagram of a single phase line of the power supply device of a synchronous motor according to a first example of a second embodiment.

represents a block diagram of a single phase line of the power supply device of a synchronous motor according to a second example of the second embodiment.

represents an electrical principle diagram of a power supply device for a synchronous motor according to a third example of the second embodiment.

represents a graph representing inductance current versus time and phase output current.

DETAILED DESCRIPTION

The figures are presented for information purposes only and in no way limit the invention.

There shows a representation of an electrical principle diagram of a power supply device for a synchronous motor comprising a Buck-boost type voltage sine inverter converter 1, connected to the windings of a stator forming in this example three phases P1, P2, P3. The inverter converter 1 therefore comprises in this example three phase lines described in detail below and a control unit U1 controlling transistors of each phase line. Of course, the inverter converter 1 can have other phase lines, for controlling a synchronous motor with more than three phases.

There is a general illustration of a phase line in a power supply device of a synchronous motor as shown in . The letter i in the references of this figure identifies the phase line connected to the Pi phase of the motor. In this example all the phase lines are identical.

The buck-boost type voltage sine inverter converter 1 allows, in a so-called “ boost ” mode, to raise the voltage, when the value of the outgoing voltage is greater than the value of the incoming voltage, or in a mode step-down so-called “ buck ” to lower the voltage, when the value of the outgoing voltage is lower than the value of the incoming voltage. During a motor start-up phase, the inverter converter 1 is in step-down mode.

The voltage sine inverter converter 1 comprises a phase output 1Pi per phase Pi of the motor and therefore per phase line, i.e. in this case a first, a second, a third, phase output 1P1, 1P2, 1P3, each respectively connected to the corresponding first, second, third phase P1, P2, P3 of the synchronous motor ( ). More generally, in an example of a motor comprising n phases, the converter will include as many phase outputs.

The Voltage Sine Inverter 1 converter includes two DC voltage inputs (a positive input and a negative input) connected to a DC power source 2.

The power supply device comprises a control unit U1 of the inverter converter 1 to control the electrical supply of each phase Pi, P1, P2, P3 of the synchronous motor. As explained in more detail below, the control unit provides the switching control signals for the transistors of the inverter converter 1.

The starting device comprises for each phase, a closed current regulation loop comprising a phase current sensor 1i of the TI current transformer type per phase output 1Pi, to measure the current in each phase output of the inverter converter 1; this phase current sensor 1i being connected to the control unit U1 to transmit to it, in a normal operating mode, a signal representative of the RMS phase current IPi of the corresponding phase output. We thus have in the example illustrated on the , a first, a second, and a third phase current sensor of the TI current transformer type 11, 12, 13; each of these phase current sensors 11, 12, 13 being connected to the control unit U1 to transmit to it, in a normal operating mode, a signal representative of the respective RMS phase current, IP1, IP2, IP3 of the output corresponding phase, respectively 1P1, 1P2, 1P3. The connection between each phase current sensor 11, 12, 13, and the control unit U1 is not shown on the but is represented on the between the phase current sensor 1i, and the control unit U1.

The phase output current IPi, circulating in phase Pi during the start-up phase, represented by an arrow on the , is a constant current not measurable by the phase current sensor 1i.

The inverter converter 1 comprises a step-down block i9 per phase line, comprising transistors Ri+, Ri- connected in series, across the DC supply voltage source 2 and controlled by the control unit U1. to cut the tension. The converter 1 therefore comprises a step-down block i9 per phase output, i.e. a first, a second, a third, step-down block respectively referenced 19, 29, 39 on the .

So in the example of the , each step-down block 19, respectively 29 and 39 comprises two transistors R1+ and R1-, respectively R2+ and R2- and R3+ and R3-, connected in series between the positive input 1+ and the negative input 1N of the source 2 of DC supply voltage.

The inverter converter 1 further comprises a step-up block i0 per phase output 1Pi and therefore per phase line, each comprising transistors Si, Si' controlled by the control unit U1, each connected to a phase output 1Pi. More precisely, the transistor Si is connected to the phase output 1Pi and the transistor Si' is connected to the negative input of the power source 2. Thus and with reference to the example illustrated in , the inverter converter 1 comprises a first, a second, a third, step-up block 10, 20, 30 each respectively connected to the first, second and third, phase output 1P1, 1P2, 1P3.

Each step-up block i0 10, 20, 30 comprises in this example two transistors Si and Si' respectively, connected in series between the negative input and the corresponding phase output. On the , the step-up block 10, respectively 20 and 30, corresponding to the phase output 1P1, respectively 1P2 and 1P3, thus comprises the two transistors S1, S1', respectively S2, S2' and S3 and S3'.

The two transistors Si, Si' in series of each step-up block i0 form a half-bridge called step-up arm, and a first node (serial connection) between them. The two transistors Ri in series of each step-down block form a half-bridge called step-down arm, and a second node (serial connection) between them.

On the , the control connection between each transistor Ri+, Ri- or Si, Si+, and the control unit U1 is not shown. On the , for the step-up block i0, a driver Di0 for controlling the transistors Si, Si' is shown, which is controlled by the control unit U1; for the step-down block i9 there is shown a driver Di9 for controlling the transistors Ri-, Ri+, also controlled by the control unit U1.

The inverter converter 1 further comprises an inductor Li per phase output (therefore per phase line), connected between the second and first node, respectively of the corresponding step-down block 1i, and of the corresponding step-up block i0. Either in this embodiment of the : a first, a second, a third, inductor L1, L2, L3, respectively connected between the second and the first node, respectively of the corresponding step-down block 19, 29, 39, and of the corresponding step-up block 10, 20, 30.

The control unit U1 is also connected to each phase output 1Pi, in the example, to measure a corresponding output voltage Voi as well as to the positive input of the voltage source 2 to measure the voltage d positive input V _{e .} Of course, the control unit U1 is also connected to ground, particularly for its power supply. The control unit can also be connected to a voltage power supply (not shown) to power it.

The inverter converter 1 further comprises a capacitor CPi per phase output 1Pi. Either on the a first, a second, a third capacitor CP1, CP2, CP3. Each capacitor CP1, CP2, CP3 is mounted between a respective phase output 1P1, 1P2, 1P3 and a neutral. The neutral can be connected to the negative terminal of power source 2 or/and to the neutral of the stator phases of the synchronous machine when it is star-mounted. In other words, the output voltage Voi of each phase Pi is equal to the voltage of the corresponding capacitor CPi.

The control unit U1 is configured, in start-up mode, to evaluate for each phase output 1Pi, an average value of direct phase current IPi circulating in the corresponding phase of the synchronous machine, as a function at least of the signal representative of the current continuous variable unidirectional inductance ILi transmitting a current to the step-up block i0, of the corresponding phase output 1Pi.

The phase output current IPi has an average value equal to the average value of the unidirectional variable current circulating in the inductor Li.

In other words, the control unit U1 is configured to estimate at start-up a direct current value IPi transmitted to the phase Pi of the synchronous machine as a function of the signal representative of the inductance current ILi, received by the current sensor 10i inductor.

Thus the control unit U1 and each inductance current sensor 10i together make it possible to calculate or estimate the phase current value IPi of each phase during at least the period when the phase current sensor 1i of the current transformer type TI cannot measure this constant direct current.

The control unit allows, in start-up mode, to adapt the control of the transistors Si, Si', and Ri+, Ri- of the step-down and step-up blocks as a function of a setpoint received and the average direct current value of phase IPi evaluated according to a switching period Tsi and a cyclic charge ratio of the inductance αci. The control unit U1 in start-up mode thus comprises a control of the inverter converter 1 in discontinuous mode, conducting an inductance current I _Li which is a triangular-shaped signal such as that of the , varying between a zero value and a peak value, according to a cyclic ratio controlled during a switching period Tsi, such that the desired phase current measurement (depending on the setpoint and the regulation loop) corresponds to the average value of the calculated inductance current.

There schematically represents the inductance current I _L as a function of time, over a switching period Tsi, circulating in one of the inductances Li, for example in the inductance L1, in starting mode (in locked rotor condition or in starting) of the synchronous motor.

An example of a current supply signal IL in an inductor Li is shown on the . We can see on this , that the current IL passing through the inductance Li has a triangular-shaped signal. The inductance current I _L is a direct but not constant current; it is a unidirectional variable current, of periodic triangular shape. This unidirectional variable inductance current I _L therefore has a linear slope rising from zero amperes to a peak value i _pk during comprising a first load period Tci corresponding to the duty cycle of the inductance αci. This unidirectional variable inductance current I _L therefore then has a linear downward slope from the peak value i _pk to zero amperes during a second discharge period Tdi corresponding to a cyclic discharge ratio of the inductance dci.

In this example, the unidirectional variable inductance current I _L has a zero intermediate period T0i during the switching period Tsi, at zero amperes, however the period T _{s i} of the unidirectional variable current can be devoid of this third zero intermediate period T0i .

In this embodiment, the control unit U1 comprises a memory in which an impedance value li of each inductance Li is stored. Of course, the inductors Li can preferentially have the same impedance value li and therefore the control unit U1 can memorize a single impedance value li. The control unit U1 is configured to calculate the average phase direct current value IPi according to the formula: .

Thus in this embodiment, as the control unit U1 controls the transistor Ri+, the control unit U1 knows the time of the charging period Tci. In addition to the control unit U1 controlling the other transistors Ri-, Si, Si', the control unit U1 knows the duty cycle of the inductance αci, as well as the switching period Tsi. The control unit U1 uses these characteristics of the signal representative of the unidirectional variable direct current IL with the input voltages Ve and output Voi to calculate the average value of phase direct current IPi according to the previous formula. Such an embodiment advantageously makes it possible to avoid having to provide another current measurement sensor which would be specifically used in start-up mode.

Figures 3 and 4 each respectively represent a first and second example of an electrical diagram of a principle diagram of a single phase line (like that of the ) of the power supply device 1', 1'' of a synchronous motor according to a second embodiment.

The power supply device 1', 1'' of this second embodiment is identical to the example of the first embodiment except in that the inverter converter 1 further comprises an inductance current sensor 10i by inductance Li , connected to the control unit U1', U1''. The 10i inductance current sensor is for example a TI transformation current sensor.

The unidirectional variable direct current of inductance I_Liis measurable by the 10i inductance current sensor of the TI transformation type unlike the constant current at the IPi phase output. The inductance current sensor 10i transmits a signal representative ILi of the inductance current I_Li has the control unit U1’.

Furthermore, in this first example of this second embodiment represented in , the control unit U1' is devoid of input voltage measurement Ve and phase output voltage measurement Voi. In this first example, the control unit U1' comprises a transformation block Fi of the representative signal ILi of the inductance current I _{L i} into an average value of the inductance current I _{L i .} Thus the control unit U1' estimates the average value of direct phase current IPi which is equal to the average value of the signal representative ILi of the inductance current I _{L i} . The transformation block Fi can be a low pass filter.

The second example of this second embodiment represented in is identical to the first example of this second embodiment except in that the control unit U1'' does not have the transformation block and is connected, as in the first embodiment, to each corresponding phase output 1Pi for measure the output voltage Voi. Furthermore, the control unit U1'' comprises a memory in which an impedance value li of each inductance Li is stored (as in the first embodiment).

• mémoriser dans chaque période de découpage Tsi, le courant max i_pkdu signal représentatif ILi du courant d’inductance I_{Li ,}
• calculer un rapport cyclique de décharge de l’inductance αdi correspondante αdi selon la formule et
• calculer la valeur moyenne du signal représentatif ILi du courant d’inductance selon la formule .

In this example the control unit U1 is configured for:

• memorize in each switching period Tsi, the maximum current i _pk of the signal representative ILi of the inductance current I _{Li ,}
• calculate a discharge duty cycle of the corresponding inductance αdi αdi according to the formula And
• calculate the average value of the representative signal ILi of the inductor current according to the formula .

In start-up mode, each inductance current sensor 10i transmits to the control unit U1 a signal representative of the current passing through the corresponding inductance. On the , the connection between each of the inductance current sensors 101, 102, 103, and the control unit U1 is not shown.

There represents an electrical principle diagram of a power supply device 1''' of a synchronous motor according to a third example of the second embodiment.

The power supply device 1''' according to this third example is similar to the second example of the second embodiment except in that the power supply device 1''' only comprises two phase current sensors 11, 12, TI current transformer type. In this case, the line from the third phase output 1P3 to phase P3 of the motor does not have an IT type phase current sensor. The control unit U1 is configured to, in normal operating mode, calculate the phase current IP3 from the RMS current values transmitted by the two other phase current sensors 11, 12.

Also, in this third example, each phase current sensor 11, 12 is integrated into the inverter converter 1. This removal of a TI type phase current sensor 1i can also be adapted on the power supply device 1, 1' of the first example of the first or second embodiment.

Furthermore, in this third example of this second embodiment in the connection respectively of the first, the second and the third inductance current sensor 101, 102, 103 to the control unit U1 to transmit to it a signal representative of the inductance current I _L circulating in the respective inductance, L1 , L2, L3.

As in the first embodiment, in the examples of the second embodiment, in start-up mode, the phase current sensor 1i being of the current transformer type TI does not make it possible to provide a measurement of the phase output current IPi, which is then a constant direct current DC represented in dotted lines (regular) on the .

In these different examples of the second embodiment, the inductance current sensor 10i, of each inductance Li allows, during the start-up mode, to measure the inductance current I_Lunidirectional variable since it is not constant, and thus transmit a signal representative of the inductance current IL to estimate the current means circulating in each 1Pi phase output according to the two examples described. In fact, the average value of the inductance current I_Lipassing through the inductance Li, is equal to that of the current circulating in the windings of the corresponding phase P1, P2, P3 of the synchronous machine.

• recevoir une consigne de démarrage,
• évaluer pour chaque sortie de phase 1Pi , une valeur moyenne de courant continu de phase IPi circulant dans la phase correspondante de la machine synchrone, en fonction au moins du signal représentatif ILi du courant continu variable unidirectionnel d’inductance transmettant un courant au bloc élévateur i0 de la sortie de phase 1Pi correspondant,
• adapter la commande des transistors Si, Si’, Ri+, Ri- en fonction de la consigne et de la valeur moyenne de courant continu de phase IPi évaluée circulant dans la phase Pi correspondante de la machine synchrone.

In the different embodiments and examples which have just been described, the power supply device 1, 1', 1'', 1''' makes it possible to carry out the steps of a closed current regulation loop:

• receive a start instruction,
• evaluate for each phase output 1Pi, an average value of phase direct current IPi circulating in the corresponding phase of the synchronous machine, as a function of at least the representative signal ILi of the unidirectional variable direct current of inductance transmitting a current to the step-up block i0 of the corresponding 1Pi phase output,
• adapt the control of the transistors Si, Si', Ri+, Ri- as a function of the setpoint and the average value of direct current of phase IPi evaluated circulating in the corresponding phase Pi of the synchronous machine.

• une sous étape de mesure de la tension de sortie Voi, à chaque sortie de phase 1Pi et
• une sous étape de mesure de la tension d’entrée positive V_ed’une source de tension continue,
• une sous étape de calcul de la valeur moyenne de courant continu de phase IPi selon la formule : .

In the case of the first embodiment, the control unit U1 comprising the value li of the stored inductance, the method comprises in the evaluation step:

• a sub-step of measuring the output voltage Voi, at each phase output 1Pi and
• a sub-step of measuring the positive input voltage V _e of a direct voltage source,
• a sub-step of calculating the average value of phase direct current IPi according to the formula: .

• une sous étape de mesure d’un signal représentatif ILi du courant d’inductance I_{L i}circulant dans chaque inductance Li,
• une étape d’estimation de chaque valeur moyenne de courant continu de phase IPi en fonction de signal représentatif ILi du courant d’inductance I_{L i}circulant dans chaque inductance.

According to the second embodiment, the method comprises in the evaluation step:

• a sub-step of measuring a signal representative ILi of the inductance current I _{L i} circulating in each inductance Li,
• a step of estimating each average value of direct phase current IPi as a function of representative signal ILi of the inductance current I _{L i} circulating in each inductance.

• une sous étape de transformation du signal représentatif ILi du courant d’inductance I_{L i}en une valeur moyenne du signal représentatif ILi du courant d’inductance,
• dans lequel la valeur moyenne de courant continu de phase IPi évaluée pour chaque phase est égale à la valeur moyenne du signal représentatif ILi du courant d’inductance I_Licorrespondante.

In particular in the first example of the second embodiment, the evaluation step:

• a sub-step of transforming the signal representative ILi of the inductance current I _{L i} into an average value of the signal representative ILi of the inductance current,
• in which the average value of phase direct current IPi evaluated for each phase is equal to the average value of the signal representative ILi of the corresponding inductance current I _Li .

• une sous étape de mesure des tensions de sortie Voi, à chaque sortie de phase,
• une sous étape de mémorisation dans chaque période de découpage Tsi, le courant max i_pkdu signal représentatif ILi du courant d’inductance I_Li,
• une sous étape de calcul d’un rapport cyclique de décharge de l’inductance αdi correspondante αdi selon la formule et
• une sous étape de calcul de la valeur moyenne du signal représentatif ILi du courant d’inductance I_Liselon la formule I_Li= .

In this case of the second example of the second embodiment, the control unit U1'' understands the value li of the stored inductance and the method comprises in the evaluation step:

• a sub-step of measuring the Voi output voltages, at each phase output,
• a storage sub-step in each switching period Tsi, the maximum current i _pk of the signal representative ILi of the inductance current I _Li,
• a sub-step of calculating a cyclic discharge ratio of the corresponding inductance αdi αdi according to the formula And
• a sub-step of calculating the average value of the representative signal ILi of the inductance current I _Li according to the formula I _Li = .

Unless otherwise specified, the same element appearing in different figures presents a unique reference.

Claims (11)

Power supply device for a synchronous motor comprising:

• a Buck-boost type sine voltage inverter converter (1, 1', 1'', 1''') comprising:
  • two direct current voltage inputs each intended to be connected to a direct current power source (2),
  • a number N of phase outputs (1Pi) forming a multi-phase system, each intended to be connected to a corresponding phase connection (Pi) of the synchronous motor,
• and for each phase output (1Pi):
  • a step-up block (i0) comprising a step-up arm connected to the corresponding phase output (1Pi), the step-up arm comprising two transistors (Si, S'i) connected together to a first node,
  • a step-down block (i9) comprising two transistors (Ri+, Ri-) connected together to a second node and between the two direct voltage inputs,
  • an inductance (Li) connected between said first and second node, to transmit a current ILi from the step-down block (i9) to the step-up block (i0) of the corresponding phase output,
• characterized in that it further comprises a control unit (U1, U1', U1'') of the transistors of said converter-inverter to control the electrical supply of each phase of the synchronous motor, the control unit being configured to , in a start mode for each phase:
  • evaluate an average value of phase direct current IPi circulating in the corresponding phase of the synchronous machine, as a function of at least one signal representative of the unidirectional variable direct current of inductance ILi transmitting a current to the step-up block (i0) of the output corresponding phase (1Pi),
  • adapt the control of the transistors (Si, Si', Ri+, Ri-) of the step-down block and the step-up block as a function of a setpoint received and the average value of direct phase current IPi evaluated according to a switching period Tsi and a duty cycle charge of the inductance αci.

Power supply device for a synchronous motor according to claim 1, in which the control unit (U1) is connected:

• at each phase output (1Pi) to measure the output voltage Voi and
• at the positive input to measure the positive input voltage Ve of a direct voltage source,
• and in that the control unit (U1) comprises a memory in which a value li of the inductance (Li) is stored for each phase and the control unit is configured to calculate the average value of direct current of IPi phase according to the formula: .

Device for powering a synchronous motor according to claim 1, comprising an inductance current sensor (10i) by inductor (Li) measuring a signal representative (ILi) of the inductance current I _{L i} circulating in the inductor (Li) to the corresponding step-up block (i0), the inductance current sensor (10i) being connected to the control unit (U1', U1'') to transmit information on the inductance current I _{L i} to evaluate the average value of phase direct current IPi. Device for powering a synchronous motor according to claim 3, in which the control unit (U1') comprises a block for transforming (Fi) the representative signal (ILi) of the inductance current I _{L i} into a value average of the representative signal (ILi) of the inductance current I _{L i} , the estimated average value of direct phase current IPi being equal to the average value of the representative signal (ILi) of the inductance current I _{L i} . Power supply device for a synchronous motor according to claim 4, in which the transformation block (Fi) is a low pass filter. Device for powering a synchronous motor according to claim 3, in which the control unit (U1'') is connected to each phase output (1Pi) to measure the output voltage Voi and comprises a memory in which a li value of each inductance (Li) is memorized and the control unit is configured for, for each phase:

• memorize in each switching period Tsi, the maximum current i _k signal representative of the inductance current I _{L i} ,
• calculate a discharge duty cycle of the corresponding inductance αdi αdi according to the formula And
• calculate the average value of the representative signal (ILi) of the inductance current I _{L i} according to the formula ₌ .

Device for powering a synchronous motor according to any one of claims 3 to 6, in which the inductance current sensor (10i) is of the TI current transformer type. Power supply device for a synchronous motor according to one of the preceding claims, the power supply device comprises at least N-1 phase current sensors (1i) of the TI current transformer type each mounted on a phase output ( 1Pi) respectively for measuring, in a normal operating mode, the current IPi in said phase output (1Pi), each phase current sensor (1i) being able to transmit to the control unit (U1, U1', U1'') a signal representative of the measured phase current IPi,
and in which the control unit (U1, U1', U1'') is configured in normal operating mode, to adapt the control of the transistors of the step-down and step-up blocks (Si, Si', Ri+, Ri-) as a function of the signal representative of the measured phase current IPi. Device for powering a synchronous motor according to claim 8, in which the number of phase current sensors (1i) of the TI current transformer type is equal to the number N of phase outputs (1Pi). Assembly comprising a power supply device for a synchronous motor according to any one of claims 1 to 9 and a synchronous motor comprising a number N of phases (Pi) each connected to a respective phase output (1Pi). Method for starting the synchronous motor of an assembly according to claim 10 comprising the steps of a closed current regulation loop:

• receive a start instruction,
• and for each phase output (1Pi):
  • evaluate an average value of direct phase current IPi circulating in the corresponding phase of the synchronous machine, as a function at least of the signal representative of the unidirectional variable direct current of inductance ILi transmitting a current to the step-up block (i0) of said phase output (1Pi),
  • adapt the control of the transistors (Si, Si', Ri+, Ri-) of the step-down and step-up blocks as a function of the setpoint and said average value of phase direct current IPi.