Electronic diagnostic method for an electric powertrain in an automotive vehicle
The electronic diagnostic process for hybrid and electric vehicle inverters addresses transistor dysfunction by analyzing piloting frequency and current variations, enhancing detection of anomalies and optimizing operation.
Patent Information
- Application Number
- FR2022002911
- Authority / Receiving Office
- FR · FR
- Patent Type
- Patents
- Current Assignee / Owner
- Filing Date
- 2022-03-31
- Publication Date
- 2025-01-31
- Estimated Expiration
- 2042-03-31
AI Technical Summary
Existing hybrid and electric vehicle inverters face issues with transistor dysfunction leading to increased energy consumption, noise, and wear due to switching losses, which are not effectively detected by current diagnostic methods.
An electronic diagnostic process that includes continuous control of the electric machine's piloting frequency, current measurement, and Fourier transform analysis to detect anomalies and determine optimal operating frequencies, using a control unit to implement this process.
Effectively detects inverter anomalies and determines optimal operating frequencies, reducing energy consumption and noise, and ensuring efficient vehicle operation.
Smart Images
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Abstract
Description
Title of the invention: Method for electronic diagnosis of an electric powertrain for a motor vehicle Technical field
[0001] The invention relates to the field of electric or hybrid vehicles and more specifically to a diagnostic method for a hybrid or electric vehicle inverter. Prior art
[0002] In a known manner, a hybrid vehicle comprises a battery, an electric machine and a heat engine. The electric machine is capable of operating in two operating modes: a motor operating mode, in which the electric machine converts electrical energy supplied by the battery into mechanical energy in order to start the heat engine, and a generator operating mode, in which the electric machine converts the mechanical rotational energy of the heat engine into electrical energy stored in the battery.
[0003] In particular, the electric machine and the battery make it possible to supply electrical energy to the vehicle's electrical network in order to supply direct voltage to various pieces of equipment in the vehicle.
[0004] In the case of a three-phase electric machine, the electric machine commonly comprises three coils.
[0005] In order to control the electric machine, an inverter is connected between the battery and the electric machine. In this case, the inverter is capable of generating three alternating currents out of phase with each other, from the voltage supplied by the battery. Each alternating current generated makes it possible to power a coil of the electric machine.
[0006] To generate the three alternating currents, the inverter comprises three power levels. Each power level comprises a first MOSFET transistor called "high" since its drain is connected to the battery and a second MOSFET transistor called "low" since its source is connected to ground. The drain of the low transistor is connected to the source of the high transistor. It is at the midpoint connecting the two transistors that the current is generated to power the corresponding coil of the electrical machine. The transistors used can also be of the insulated gate bipolar type.
[0007] However, each element of the drive chain wears out. For example, each transistor, intended to switch many times, suffers switching losses. A malfunction of a transistor could cause the inverter to malfunction. In order to detect a malfunction of the inverter, it is known to measure the voltage between the drain and source of each MOSFET transistor and compare the measured values with reference values. The voltage between the drain and the source is representative of the residual resistance of the MOSFET transistor. Indeed, a burnt-out transistor has a very high residual resistance.
[0008] In addition, worn elements can also cause disturbing noise for the vehicle user and increase the vehicle's electrical energy consumption. This is the case, for example, of the input inductance, designating the EMC filter for "Electromagnetic Compatibility", connected to the input of the inverter.
[0009] There is therefore a need for a solution that can at least partially overcome the drawbacks described above. Statement of the invention
[0010] To this end, the invention relates to a method for electronic diagnosis of an electric powertrain for an electric or hybrid motor vehicle, the powertrain comprising an electric battery, an electric machine, an inverter connected between the battery and the electric machine, and a connecting capacitor connected in parallel between the battery and the inverter, the diagnostic method comprising the steps: i. continuous control of the increase in the control frequency of the electric machine from a minimum value to a maximum value, ii. continuous measurement of the current value between the assembly comprising the battery and the capacitor and between the inverter during the control stage, iii. determination of the variation of the Fourier transform of the received current variation as a function of the control frequency, iv. for each pilot frequency: 1. detection of an anomaly if at least one value of the Fourier transform is outside a predefined Fourier transform interval for said control frequency, 2. otherwise, determining when said driving frequency value is optimal if the value of the Fourier transform for said driving frequency is less than a predefined threshold.
[0011] Thus, the method makes it possible to detect an anomaly, making it possible to indicate an anomaly of malfunction of the inverter, from the measurement of current variation during the variation of the control frequency of the electrical machine and the Fourier transform of the current variation thus measured. In addition, the method also makes it possible to determine at least one optimal control frequency, making it possible to obtain efficient and optimal operation of the electrical machine.
[0012] Preferably, the method comprises before the step of controlling the increase of the piloting frequency, a detection step when the vehicle speed is substantially constant.
[0013] More preferably, the method comprises a preliminary phase of detecting the environmental conditions making it possible to implement the method presented here.
[0014] More preferably, the minimum value of the driving frequency is between 18.0 and 19.5 KHz and the maximum value of the driving frequency is between 20.5 and 22.0 KHz.
[0015] Advantageously, the electrical machine comprising at least two coils, the inverter comprising at least two power circuits, each power circuit comprising a first switch called "high", connected between the battery and a midpoint specific to said power circuit, and a second switch called "low", connected between the midpoint and a ground, each power circuit being capable of supplying an alternating current at its midpoint, each power circuit being connected to a coil of the electrical machine via its midpoint, each high switch and each low switch is characterized by a switching frequency, the step of controlling the driving frequency of the electrical machine designating the step of controlling the switching frequency of the switches of each power circuit of the inverter.
[0016] The invention also relates to a computer program product which is remarkable in that it comprises a set of program code instructions which, when executed by one or more processors, configure the processor(s) to implement a method as presented previously.
[0017] The invention also relates to a control unit for an electric powertrain for an electric or hybrid motor vehicle, the powertrain comprising an electric battery, an electric machine, an inverter connected between the battery and the electric machine, and a connecting capacitor connected in parallel between the battery and the inverter, the control unit being capable of implementing the method as presented previously.
[0018] Preferably, the electrical machine comprising at least three coils, the inverter comprising at least three power circuits, each power circuit comprising a first switch called "high", connected between the battery and a midpoint specific to said power circuit, and a second switch called "low", connected between the midpoint and a ground, each power circuit being capable of supplying an alternating current at its midpoint, each power circuit being connected to a coil of the electrical machine via its midpoint, each high switch and each low switch is characterized by a switching frequency, the control unit being capable of implementing the method as presented previously.
[0019] The invention also relates to a motor vehicle comprising a chain of electric traction, the traction chain comprising an electric battery, an electric machine, an inverter connected between the battery and the electric machine, a connecting capacitor connected in parallel between the battery and the inverter, and a control unit as presented previously. Brief description of the drawings
[0020] Other characteristics and advantages of the invention will become apparent from reading the description which follows. This is purely illustrative and must be read in conjunction with the appended drawings in which:
[0021] [Fig.l] is a schematic view of an electric powertrain of an electric or hybrid vehicle according to the invention.
[0022] [Fig.2] is a detailed illustration of an inverter and an electrical machine according to [Fig.l].
[0023] [Fig. 3] is an illustration of the method according to the invention. Description of the embodiments
[0024] Vehicle
[0025] An embodiment of an electric powertrain for an electric or hybrid vehicle according to the invention will now be presented. With reference to [Fig.l], the powertrain comprises a battery 10, an electric machine M, an inverter 20, a control unit 30 of the inverter 20 and a capacity of C2o-
[0026] The battery 10 is capable of providing a direct voltage in order to supply electrical energy to various equipment mounted in the vehicle. In the present case, the battery is in particular capable of supplying power to the electrical machine M.
[0027] The electric machine M designates in particular a permanent magnet electric motor when the vehicle is electric or an electric motor more commonly called an alternator-starter or BSG for “Belt Starter Generator” by those skilled in the art when the vehicle is hybrid.
[0028] Electric machine M
[0029] The electric machine M is capable of operating in two operating modes: a motor operating mode, in which the electric machine M converts electrical energy into mechanical energy, and a generator operating mode, in which the electric machine M converts mechanical energy into electrical energy stored in the battery 10. For example, if the vehicle is hybrid, then in the motor operating mode, the electric machine M converts electrical energy into mechanical energy in order to start the thermal engine and in the generator operating mode, the electric machine M converts the mechanical rotational energy of the thermal engine into electrical energy stored in the battery 10.
[0030] Usually, an electrical machine M comprises at least two phases and a number of coils identical to the number of phases. In the example presented below, the electrical machine M is three-phase and comprises three coils L1, L2, L3.
[0031] Inverter 20
[0032] The inverter 20 is connected between the battery 10 and the electric machine M in order to control the electric machine M.
[0033] The inverter 20 is capable of generating at least one alternating current from the voltage supplied by the battery 10. Each alternating current generated by the inverter 20 makes it possible to power a coil L1, L2, L3 of the electrical machine M. Thus, since the electrical machine M comprises three coils L1, L2, L3, the inverter 20 is capable of generating three alternating currents, out of phase with each other.
[0034] The control unit 30 is capable of controlling the inverter 20, in order to define the conversion of the voltage between the battery 10 and the electrical machine M.
[0035] With reference to [Fig.2], the detailed structure of the inverter 20 is described.
[0036] To generate each alternating current, the inverter 20 comprises a so-called “power” circuit. According to the example presented here, the inverter 20 is capable of generating three out-of-phase alternating currents to power the electrical machine M and the inverter 20 therefore comprises three power circuits C1, C2, C3.
[0037] Each power circuit C1, C2, C3 comprises a first switch called “high” Ihb Ih2, Ih3 and a second switch called “low” In, Ii2, Ib
[0038] The first switch Ih1, Ih2, Ih3 of each power circuit C1, C2, C3 is connected between the battery 10 and a midpoint PMI, PM2, PM3 specific to said power circuit C1, C2, C3.
[0039] The second switch In, Ii2, IB of each power circuit Cl, C2, C3 is connected between the midpoint PMI, PM2, PM3 specific to said power circuit Cl, C2, C3 and a ground.
[0040] Thus, for each power circuit Cl, C2, C3, the first switch Ihb Ih2, Ih3 and the second switch In, h2, L are connected to each other via the midpoint PMI, PM2, PM3 specific to said power circuit Cl, C2, C3.
[0041] Each power circuit C1, C2, C3 thus generates an alternating current at its midpoint PMI, PM2, PM3.
[0042] Thus, the midpoint PMI of the first power circuit C1 is connected to the first coil L1 of the electrical machine M, the second midpoint PM2 of the second power circuit C2 is connected to the second coil L2 and the third midpoint PM3 of the third power circuit C3 is connected to the third coil L3.
[0043] Preferably, each switch Ihb Ih2, Ih3, In, I[2, IB is a transistor for example of the MOSFET or insulated gate bipolar type or “IGBT” for “Insulated Gate Bipolar Transistor” in English. According to the example described, the switches are MOSFET type.
[0044] Each high switch Ihb Ih2, Ih3 and each basin switch, I12, U is characterized by a switching frequency, in other words, by an opening and closing frequency. Each high switch Ihb Ih2, Ih3 and each basin switch, I12, U is also characterized by a duty cycle defining the opening duration relative to the closing duration of said switch.
[0045] The control unit 30 of the inverter 20 is capable of controlling the opening and closing of each high switch Ihb Ih2, Ih3 and each basin switch, I12, I13 as a function of the amplitude and frequency of the alternating currents to be supplied.
[0046] More precisely, the control unit 30 is configured to control the variation of the switching frequency and the variation of the duty cycle characterizing each high switch Ihb Ih2, Ih3 and each basin switch, I12, U-
[0047] In addition, the control unit 30 comprises a memory area in which a time counter is recorded.
[0048] C2o binding capacity
[0049] The connecting capacitor C20 is also connected in parallel between the battery 10 and the inverter 20. In other words, the capacitor C20 is connected on the one hand between the battery 10 and the inverter 20 and on the other hand to a ground.
[0050] The connecting capacitor C20 is capable of suppressing residual oscillations of a voltage supplied between the battery 10 and the inverter 20, in particular so as not to damage the battery 10. In addition, when each high switch Ihb Ih2, Ih3 and each basin switch I12, L are closed, this creates a current draw in said switch. Conversely, the current in said switch Ihb Ih2, Ih3, In, h2, IB decreases or is cancelled when said switch is open. The connecting capacitor C20 thus makes it possible to compensate for current variations in order to protect the battery 10.
[0051] Method
[0052] With reference to [Fig. 3], an embodiment of the method according to the invention will be shown, implemented by the electric traction chain, and therefore by a control unit 30, as presented previously.
[0053] The method is implemented at regular time intervals. For example, the method is implemented weekly. For this, the method is implemented from the moment when the time counter has reached a predefined time threshold value. The time threshold value may designate a number of seconds, hours or days, defining for example a week.
[0054] In addition, the method may also comprise a preliminary phase E0 of detecting the environmental conditions allowing the method to be implemented correctly. For example, the environmental conditions relate to temperature. An optimal temperature for implementing the method is defined between 15 and 30 degrees.
[0055] Detection step El constant vehicle speed
[0056] The method firstly comprises a detection step E1 when the speed of the vehicle is substantially constant. By “substantially constant speed”, for example, is meant a speed whose variation is always at a minimum at a threshold over a predefined period of time. For example, during the detection step, a constant speed designates a variation in speed of less than 10% over a period of 30 seconds.
[0057] The rest of the method is implemented after the EL detection step.
[0058] In addition, the method regularly comprises a step of verifying the speed constancy. Indeed, the rest of the process can only be carried out when the speed is substantially constant.
[0059] Frequency command E2
[0060] The method also comprises a step E2 of continuously controlling the increase in the control frequency of the electrical machine, in other words the control frequency of the switches Ihi, Ih2, Es, In, I12, I13 of each power circuit C1, C2, C3 of the inverter 20 from a minimum value to a maximum value.
[0061] By "continuously" is meant the fact of increasing at regular time intervals the frequency by a predefined frequency step, from the minimum value until reaching the maximum value.
[0062] For example, the switching frequency of the switches Ihi, Ih2, Ih3, In, I12, I13 is controlled between 18 KHz and 22 KHz.
[0063] Measurement of current E3
[0064] The method then comprises a step E3 of continuously measuring the value of the current between the assembly comprising the battery 10 and the capacitor C2o and between the inverter 20 during the control step E2.
[0065] The current variation thus measured as a function of the control frequency is then recorded in the memory area of the control module 30.
[0066] FFT E4 Determination
[0067] The method then comprises a step E4 of determining the Fourier transform of the current variation measured and recorded previously.
[0068] The Fourrier transform as a function of the control frequency is then recorded in the memory area of the control module 30. Furthermore, the memory area also comprises a reference table associating with each control frequency value between the minimum value and the maximum value, an interval of Fourrier transform values. Said interval defines the set of Fourrier transform values corresponding to the nominal and fault-free operation of the traction chain, for a control frequency.
[0069] analysis phase
[0070] The method then comprises a phase of analyzing the Fourier transform thus obtained.
[0071] For each control frequency, the analysis phase comprises a step E5 of detecting an anomaly if at least one value of the determined Fourier transform is outside the interval of Fourier transform values associated with said control frequency.
[0072] The detected anomaly makes it possible to demonstrate the presence of an electronic malfunction on one of the electrical components of the inverter 20 and of the capacitor C2o and / or a mechanical malfunction on one of said electrical components, in particular a conductive wire which becomes detached from the resin in which it is fixed and which vibrates.
[0073] Following the step E5 of detecting an anomaly, the method comprises an alert step E5', in which the control unit 30 sends an alert to the driver in order to warn him of the anomaly, for example by controlling the lighting of a light indicator on the dashboard of the vehicle.
[0074] The analysis phase also comprises a step E6 of determining at least one optimal control frequency. For this, the control unit 30 selects, on the previously determined Fourier transform and omitting the control frequencies for which an anomaly has been detected, all of the control frequencies for which the value of the Fourier transform is less than a predefined threshold. The predefined threshold is previously recorded in the memory area. It is obvious that the control frequencies selected during this step must not correspond to control frequencies for which an anomaly has been previously detected.
[0075] Finally, following the analysis phase, the method comprises a step E7 of resetting the value of the time counter to zero.
[0076] In particular, the method is iterated at least over at least two substantially different constant speeds. More preferably, the method is iterated over three different constant speeds.
[0077] The detected anomalies and the determined optimal control frequencies are compared between the different iterations of the process. If an anomaly is detected for the same control frequency between the different iterations of the process, then this makes it possible to confirm the validity of the detected anomalies.
[0078] Similarly, if the value of an optimal control frequency is detected on the different iterations of the method, then this makes it possible to confirm or invalidate the validity of the detected optimal control frequency.
Claims
Claims
1. Method for electronic diagnosis of an electric powertrain for an electric or hybrid motor vehicle, the powertrain comprising an electric battery (10), an electric machine (M), an inverter (20) connected between the battery (10) and the electric machine (M), and a connecting capacitor (C2o) connected in parallel between the battery (10) and the inverter (20), the diagnostic method comprising the steps: i. of continuously controlling (E2) the increase in the control frequency of the electric machine (M) from a minimum value to a maximum value, ii. of continuously measuring (E3) the value of the current between the assembly comprising the battery (10) and the connecting capacitor (C20) and between the inverter (20) during the control step (E2), iii. of determining (E4) the variation of the Fourier transform of the variation in current received as a function of the control frequency, iv.for each control frequency:
1. detection (E5) of an anomaly if at least one value of the Fourrier transform is outside a predefined Fourrier transform interval for said control frequency, 2. otherwise, determination (E6) when said control frequency value is optimal if the value of the Fourrier transform for said control frequency is lower than a predefined threshold.
2. Method according to the preceding claim comprising, before the step (E2) of controlling the increase in the piloting frequency, a step (El) of detecting when the speed of the vehicle is substantially constant.
3. A method according to any preceding claim, wherein the minimum value of the driving frequency is between 18.0 and 19.5 KHz and the maximum value of the driving frequency is between 20.5 and 22.0 KHz.
4. Method according to any one of the preceding claims, the electrical machine (M) comprising at least two coils (L1, L2, L3), the inverter (20) comprising at least two power circuits (Cl, C2, C3), each power circuit (Cl, C2, C3) comprising a first switch called "high" (Ihb Ih2, Ih3), connected between the battery (10) and a midpoint (PMI, PM2, PM3) specific to said power circuit (Cl, C2, C3), and a second switch called "low" (In, I12,1 b), connected between the midpoint (PMI, PM2, PM3) and a ground, each power circuit (Cl, C2, C3) being capable of supplying an alternating current at its midpoint (PMI, PM2, PM3), each power circuit (Cl, C2, C3) being connected to a coil (L1, L2, L3) of the electrical machine (M) via its midpoint (PM1, PM2, PM3), each high switch (Ihb Ih2, Ih3) and each low switch (In, Ii2, IB) is characterized by a switching frequency,the step of controlling the driving frequency of the electric machine (M) designating the step of controlling the switching frequency of the switches (Ihi, Ih2, Ls, In, Ii2, Ib) of each power circuit (Cl, C2, C3) of the inverter (20).,
5. A computer program product characterized in that it comprises a set of program code instructions which, when executed by one or more processors, configure the processor(s) to implement a method according to any one of claims 1 to 4.