FR3073992A1 - METHOD FOR CONTROLLING A VIENNA TRIPHASE RECTIFIER - Google Patents

Abstract

The invention relates to a method (300) for controlling a three-phase rectifier (20) comprising: - a step (301, 302, 311) for measuring currents (ImesA, ImesB, ImesC) and simple voltages (VA, VB, VC) of phases at the input of said rectifier; a step of determining (304, 305) an active power value (Pmes) and a reactive power value (Qmes) as a function of said measured currents and voltages; a step of defining (306) a first regulation (VP) for slaving said active power to a charge power reference value (Preq); a step of defining (307) a second regulation (VQ) for slaving said reactive power value to a reactive power reference value (Qreq); a step of determining (308) control voltages (V # A, V # B, V # C) to be applied to each arm of said three-phase rectifier; and a step of generating (309) cyclic ratios as a function of said control voltages (V # A, V # B, V # C).

Description

The present invention relates to a method for controlling a three-phase rectifier for a charging device with three-phase input, comprising an isolated AC-DC (alternating current-direct current) converter. Such a charging device is particularly suitable for use as an on-board device in an electric or hybrid motor vehicle.

These vehicles are fitted with high-voltage electric batteries and generally include on-board chargers, i.e. devices for charging electric batteries which are mounted directly on the vehicles. The main function of these charging devices is to recharge the batteries from the electricity available on the electricity distribution network. The criteria sought for the charging devices, and in particular for the on-board chargers, are a high efficiency, a small footprint, a galvanic isolation, a good reliability, a safety of operation, a low emission of electromagnetic disturbances, and a low rate. of harmonics on the input current.

We place ourselves here in the category of charging devices with three-phase input, which have a higher charging power compared to charging devices with single-phase input. FIG. 1 illustrates a known topology of an isolated charging device 10 on board an electric or hybrid vehicle for recharging the high voltage battery of the vehicle from the three-phase electrical network 30 to which the on board charging device 10 is connected by via line impedance 40 of the network.

In order to implement the AC-DC conversion function with galvanic isolation, it is known to use a charging device 10 comprising a first AC-DC converter, which includes a power factor corrector circuit 20 (PFC, for “ Power factor Correction ”) in order to limit the harmonics of the input current, and a second DC-DC converter (direct current to direct current) 12, to ensure the regulation of the load and also to ensure the isolation function for the safety of use. An input filter 13 is conventionally integrated at the input of the on-board charging device 10, upstream of the PFC circuit 20 relative to the three-phase electrical network 30.

The PFC 20 circuit is controlled by an integrated controller (not shown), which analyzes and corrects the shape of the current in relation to the voltage in real time. It deduces form errors by comparison with the rectified sinusoid of the voltage and corrects them by controlling the amount of energy through high frequency chopping and energy storage in an inductor. Its role is more precisely to obtain a non-phase-shifting current and as sinusoidal as possible at the input of the charger supply.

For the PFC 20 circuit, it is known, in particular from the prior art document CN104811061, to implement a three-phase three-level rectifier with three switches, commonly known as the three-phase Vienna rectifier, as described in the document d prior art EP94120245 and in FIG. 2.

The choice of this topology is in fact particularly advantageous from the performance point of view for the correction of power factor.

In a three-phase Vienna rectifier 20, each phase of the three-phase alternating input voltage 30 is connected by respective inductances La, Lb, Le to a switching arm 1, 2, 3 of the rectifier 20, which is provided with a power switch cell respectively Sa, Sb, Sc.

The power switch cells Sa, Sb, Sc each being arranged between a respective inductance La, Lb, Le and a midpoint O between the two output voltages V _D ch and V _D cl of the rectifier 20, corresponding respectively to the voltage on a first output capacitor C1 connected between the midpoint O and a positive supply line H and at the voltage on a second output capacitor C2 connected between the midpoint O and a negative supply line L.

Generally to control such a Vienna rectifier 20, the voltages Va, Vb, Vc and the currents ia, ib, ic are measured upstream of the inductances La, Lb, Le, or alternatively directly downstream of these inductances La, Lb, Le , as well as at the output of the rectifier and regulation loops are used to generate the duty cycles required to adjust the average conduction time of the switches Sa, Sb, Sc.

The state of the art on the application of the cyclic ratios on each switching arm of a three-phase Vienna rectifier consists in using one or the other of the two switches depending on the direction of current flow on the arm .

However, the known methods of the prior art for generating the duty cycles of the Vienna rectifier 20 produce fluctuating voltages across the output capacitors C1, C2, which make the regulation of DC / DC 12 relatively complex and unreliable.

In particular, from document CN104811061 previously cited, a control of the rectifier implementing complex regulation using a table of precalculated voltages as a function of the number of combinations of states of the three switches is known. Such a control is therefore not very adaptable, not very robust.

Also, a solution is sought to improve the control of the rectifier, in particular by obtaining a decoupling of the active and reactive powers and by optimizing the rejection of disturbances.

We propose a method for controlling a three-phase rectifier comprising:

a step of measuring the currents and voltages composed at the input of said rectifier;

- a step of determining an active power value and a reactive power value as a function of said measured currents and voltages;

- a step of defining a first regulation to control said active power to a load power setpoint value;

- a step of defining a second regulation to control said reactive power value to a reactive power set value;

a step of determining control voltages to be applied to each arm of said three-phase rectifier; and

a step of generating cyclic reports as a function of said control voltages.

Thus, a robust and relatively simple control can be obtained, in particular without phase-locked loop or trigonometric function, which are relatively costly in computation time. The method also makes it possible to decouple the active and reactive powers.

In this way, the power can also be controlled directly without passing through a calculation of the current setpoint.

Advantageously and without limitation, the first regulation includes a proportional action, an integral action, a desaturation action and an anticipation action. Thus, the control of the active power can be improved, by obtaining a rapid response time with an effective disturbance rejection.

Advantageously and without limitation, the second regulation includes a proportional action, an integral action and a desaturation action. Thus, the control of the reactive power can be improved by obtaining a rapid response time with an effective disturbance rejection.

Advantageously and in a nonlimiting manner, said reactive power setpoint is zero, making it possible to optimize the efficiency of the system.

However, the reactive power setpoint can also be non-zero, for example adjusted to a value adapted to meet a load standard on the network.

Advantageously and without limitation, the measurement step is followed by a step of transforming the currents measured at the input of the three-phase rectifier into currents transformed in a fixed two-phase frame. Thus, the command can be obtained in a fictitious coordinate system simplifying the calculation operations.

Advantageously and in a nonlimiting manner, the measurement step is followed by a step for calculating single voltages as a function of said compound voltages and a step for transforming said simple voltages into voltages transformed into a fixed two-phase frame. Thus, the command can be obtained in a fictitious coordinate system simplifying the calculation operations.

The invention also relates to a device for controlling a three-phase rectifier comprising:

- means for measuring the currents and voltages composed at the input of said rectifier;

- means for determining an active power value and a reactive power value as a function of said measured currents and voltages;

- means for defining a first regulation to control said active power to a load power setpoint value;

- means for defining a second regulation for slaving said reactive power value to a reactive power set value;

- means for determining control voltages to be applied to each arm of said three-phase rectifier; and

- means for generating duty cycles as a function of said control voltages.

The invention also relates to an electrical assembly comprising a three-phase rectifier and a control device as described above.

The invention also relates to a motor vehicle comprising an electrical assembly as described above.

Other features and advantages of the invention will emerge on reading the description given below of a particular embodiment of the invention, given by way of indication but not limitation, with reference to the accompanying drawings in which:

- Figure 1 is a schematic view of an electrical assembly known from the prior art;

- Figure 2 is a schematic view of a Vienna rectifier of an electrical assembly according to Figure 1; and

- Figure 3 is a flow diagram of the control method according to a first embodiment of the invention.

Figure 2 shows the structure of a three-phase Vienna rectifier 20 known from the prior art, as used in the invention.

The Vienna three-phase rectifier 2 comprises three parallel incoming connections each coupled to a phase of a three-phase power supply network 30 via a series inductor La, Lb, Le, and each connected to a pair of switches Sa, Sb, Sc forming a first, a second and a third switching arm of the Vienna three-phase rectifier.

Each pair of switches Sa, Sb, Sc comprises a series head-to-tail arrangement consisting of a first corresponding switch Sah, Sbh, Sch, which is controlled when a corresponding input current ia, ib, ic is positive, and d 'a second corresponding switch Sal, Sbl, Sel which is controlled when the corresponding input current is negative. In other words, a single switch controlled on a switching branch is used for chopping the current. The switches are formed by semiconductor components controlled on closing and opening, such as SiC-MOS transistors (acronym for Silicon Carbide-Meia / Oxide Semiconductor), connected in antiparallel with a diode. This type of semiconductor is suitable for very high switching frequencies. The Sah, Sbh, Sch switches are also called high switches and the Sal, Sbl, Sel switches, low switches.

The three-phase Vienna rectifier 20 also comprises three parallel branches 1, 2 and 3, each comprising two diodes Dah and Dal, Dbh and Dbl and Dch and Dcl, which form a three-phase bridge with six diodes allowing a unidirectional transfer of energy and to rectify the current and the voltage drawn from the three-phase power supply network 30.

Each input of the Vienna three-phase rectifier 20 is connected, by a respective parallel incoming connection, to a connection point located between two diodes of the same branch 1,2 and 3.

The two common ends of the branches 1, 2 and 3 constitute two output terminals H and L, respectively positive H and negative L, of the three-phase Vienna rectifier 20, which are intended to be coupled to the DCDC device 12.

The switching arms Sa, Sb, Sc of each phase are moreover each connected respectively between the connection point a, b, c situated between the two diodes of the first 1, second 2 and third branches 3 and a midpoint O of the voltages output V _D ch and V _D cl of the three-phase Vienna rectifier 20, corresponding respectively to the voltage on an output capacitor C1 between the positive output terminal H of the three-phase rectifier and the midpoint O and to the voltage on a capacitor of output C2 between the midpoint O and a negative output terminal L of the three-phase rectifier 20.

The voltage on the output capacitors C1, C2 is controlled independently by the DC-DC converter of the charging device connected at the output of the three-phase Vienna rectifier 20, according to the global topology illustrated in Figure 1. In other words, the voltages output of the Vienna three-phase rectifier 20 are controlled by the DC-DC converter 12.

The three-phase Vienna rectifier 20 inserted at the input of the charger supply 10 assumes the role of correction of the power factor of the charger. Such a role makes it possible to prevent the disturbing currents (harmonics) produced by the charger, from flowing through the impedance of the network, located upstream of the rectifier of Vienna 20.

The switching arms Sa, Sb and Sc of each phase of the three-phase network 30 are controlled by means of six PWM control signals (from the English "Puise Width Modulation") having a variable duty cycle with equal fixed switching frequency at 140 kHz individually adjusted by processing means of the FPGA type for example (not shown) for high sampling frequencies.

Thus, the processing means are adapted to determine the duty cycles of the switching control signals of the switches of the rectifier switching arms, necessary for the servo of the sinusoidal currents at the input of the rectifier 20.

To determine the duty cycles to be applied to the Vienna rectifier 20, a control method 300 is implemented.

First, we measure 301 the composite voltages V _A b, V _B c, V _C a, from which we calculate 302 the simple voltages V _A , V _B , V _c . The simple voltages V _A , V _B , V _c are then transformed 303 into transformed voltages v ™ ^es , v ™ ^es in a two-phase stationary frame α, β.

In this same two-phase stationary frame α, β, we transform 313 the j mes j my jmes measured phase currents ⁷ ayb, ^y c _{at the CO} urs of a measurement step 311, into transformed phase current if ^es , i ™ ^es .

From the measured voltages and currents, the active power P ^mes and the reactive power Q ^mes are calculated.

More specifically, the compound voltages (between phases), V _A b, V _B c, V _C a, are measured 301 by means known to those skilled in the art. The modulus of the network voltage vector is calculated as follows:

^ = 1 (^ + ^ + ^) (1)

The single voltages V _A , V _B , V _c between phases and neutral at the input of the Vienna three-phase rectifier are calculated 302 from the compound voltages V _AB , V _BC , V _AC between phases, as follows:

ΓΚΠ

V _B kJ

1 0 -1 'Vab' -1 1 0 VBC . 0 -1 1. yca-

(2)

These simple voltages V _A , V _B , V _{c are} then transformed 303 into a fixed two-phase frame, as follows:

Vb ^{+ v} C

V6

..mes _ ^V B ^v c (3) (4) _T mes i _T mes ^l B ^{+ i} C

V6 (5) (6) (8) j mes j mes jmes

The phase currents' / b ^l c _a t measured 311 at the input of three phase rectifier Vienna. They are then transformed 313 into transformed currents i ™ ^es , i ™ ^es in a fixed two-phase frame, as follows:

; mes _ jmes ² _ ^l a ψ _T mes _T mes tmes _ ^l B ⁱ c ^l P - ÿî

From the measured currents and voltages, the active power P ^mes is calculated 304 and the reactive power Q ^mes is calculated 305:

pmes _.-mes tmes j_ „mestmes (~ 7 \ ^r - V _a l _a h Vp Ιβ {()

Qmes _.-Me s tmes _ ^ mes tmes - a ^L p Vp ^L a

The active power P ^mes is slaved to a load power setpoint P ^req determined 306 according to the requirements and the size of the network, and the reactive power Q ^mes is slaved to a reactive power setpoint Q ^req determined 307 according to needs and network sizing. To do this, an active power regulator V _P and a reactive power regulator V _{Q are used} .

The active power regulators V _P and reactive power regulators V _{Q are} determined 308 by application of the following equations:

(9) (10) with

ÔV ^P = V _P - max {min {V _P , V _max ], V _min ] ^ÔVQ = ^V Q ~ ^max { ^min { ^V Q ' ^V max] (11) (12) with V _min and V _max respectively the values minimum and maximum of the control voltage, and "s" the Laplace operator.

Note that in equations (11) and (12) the values V _P / V _Q of the previous calculation step are used, since this process is repeated continuously.

The gains K _p and Kj respectively represent a proportional gain, which ensures the speed, and an integral gain which ensures a zero static error. The gain K _{sat is} used to avoid the instability of the control when the command is saturated.

Thus, the active power P ^mes is slaved 308 to the load power setpoint P ^req by means of a regulator V _P called the first regulation V _P , comprising a proportional action, an integral action, a desaturation action and a anticipatory action.

The reactive power Q ^mes is slaved to its setpoint Q ^req (which is zero by default) via a regulator V _Q , called the second regulation V _Q , comprising a proportional action, an integral action and a desaturation action.

The control voltages V /, generated 309, to be applied to each of the switching arms of the Vienna three-phase rectifier via the power switches, are calculated according to equation (13):

(13)

Π / ^# 1 ^Va , Γ7 -1 ⁰ 1 1 V3 • V _s ^# = - - 1 ^Vc N ³ m 2 2 1 - 2 _V3 2 -

mes 17 _ „mes ,, ^v a ^V P ^ν β ^V Q

..mesir, ^ν β ^V P ^{ψ v} a

QJ

A person skilled in the art knows how to generate the duty cycles simply, by comparison with a ramp in particular, in order to achieve the control voltages V /, V /, V / to be applied.

The reactive power setpoint Q ^req can be zero, by default, in order to optimize the efficiency of the system. However, it can be adjusted by a person skilled in the art to another value, for example so as to meet certain requirements on the harmonics of currents. In particular, the reactive power setpoint Q ^req can be chosen so as to comply with the given standards if the network voltage is disturbed.

Claims (9)

1. Method (300) for controlling a three-phase rectifier (20) comprising: a step of measuring (301, 311) of the currents, ^c ) and compound voltages (V _AB , V _B c, V _ac ) θη input of said rectifier; - a step of determining (304, 305) an active power value (p ^mes ) and a reactive power value (Q ^mes ) as a function of said measured currents and voltages; - a step of defining (306) a first regulation (V _P ) for slaving said active power to a load power setpoint value (P ^req ); - a step of defining (307) a second regulation (V _Q ) for slaving said reactive power value to a reactive power set value (Q ^req ); a step of determining (308) control voltages (Vf, Vf, Vf) to be applied to each arm of said three-phase rectifier; and - A step of generating (309) duty cycles as a function of said control voltages (Vf, Vf, Vf). 2. Method (300) according to claim 1, characterized in that the first regulation (V _P ) comprises a proportional action, an integral action, a desaturation action and an anticipation action. 3. Method (300) according to claim 1 or 2, characterized in that the second regulation (V _Q ) comprises a proportional action, an integral action and a desaturation action. 4. Method (300) according to any one of claims 1 to 3 characterized in that said reactive power setpoint (Q ^req ) is zero. 5. Method (300) according to any one of claims 1 to 4, characterized in that the measurement step (301, 311) is followed by a step of j mes j mes jmes transformation (313) of the measured currents ('/ b / cj _{at the} input of the three-phase rectifier (20) into transformed currents (i ™ ^es , i ™ ^es ) in a fixed two-phase frame (α, β). 6. Method (300) according to any one of claims 1 to 5, characterized in that the measurement step (301, 311) is followed by a calculation step (302) of single voltages (V _A , V _B , Vc) as a function of said compound voltages (V _AB , V _bc , V _ca ) and of a transformation step (303) of said simple voltages (V _A , V _B , V _c ) into transformed voltages (v ™ ^es , v ™ ^es ) in a fixed two-phase frame (α, β). 7. Control device for a three-phase rectifier (20) comprising: - means for measuring the currents (/ b, ^L c) _e t voltages (V _AB, V _BC, V _AC) at the input of said rectifier; - means for determining (304, 305) an active power value (P ^mes ) and a reactive power value (Q ^mes ) as a function of said measured currents and voltages; - means for defining (306) a first regulation for controlling said active power to a load power setpoint value (Preq); - means for defining (307) a second regulation for controlling said reactive power value to a reactive power set value (Qreq); - means for determining (308) control voltages (V _A , V _B , V _B ) to be applied to each arm of said three-phase rectifier; and - means for generating (309) duty cycles as a function of said control voltages (V _A , V ^, Vc). 8. Electrical assembly comprising a three-phase rectifier (20) and a control device according to claim 7. 9. Motor vehicle comprising an electrical assembly according to claim 8. 1/3 Network Impedance Input Filter PFC DC / DC 400V line electric battery 2/3 T _J O O 3/3 Fig.3 301 302 303