METHOD FOR THERMOREGULATING A HEAT TRANSFER CIRCUIT COMPRISING A MOTOR AND A BATTERY

Abstract

The invention relates to a method for thermoregulating a heat transfer circuit, comprising the following steps: - a measurement step (E1) of the rotational speed of a motor, the motor torque, and the voltage of a battery; - a calculation step (E2, E3) of moving averages; - a calculation step (E4, E5) of the thermal power dissipated by the motor and by an inverter; - a calculation step (E6, E7) of a first power value and a second power value dissipated by the inverter, respectively; - a calculation step (E8) by interpolation of a setpoint switching frequency value for the inverter; and - an update step (E9) of the inverter switching frequency value by substituting it with the calculated setpoint switching frequency value for the inverter. Figure 2

Description

Title of the invention: METHOD FOR THERMOREGULATING A HEAT TRANSFER CIRCUIT COMPRISING A MOTOR AND A BATTERY

[0001] The present invention relates to electric vehicles, that is to say, those equipped with at least one battery for storing electrical energy intended for their propulsion by a motor. This includes vehicles having a single means of electric propulsion, as well as hybrid vehicles incorporating at least one mode of electric propulsion.

[0002] In particular, it is known from the prior art that electric vehicles can be operated in low-temperature conditions. However, the electric vehicle battery is less efficient when the ambient temperature is low.

[0003] Patent application EP 2 540 552 B1 describes a device comprising a motor and a battery. The device comprises a first circuit and a second circuit including the motor and the battery. A heat transfer fluid circulates in the first and second circuits. The aforementioned document also includes a method comprising a first mode and a second mode. A torque is set to the motor. In the first mode, the motor operates at a first energy efficiency for the given set torque. Furthermore, in the first mode, the heat transfer fluid circulates in the first circuit and is cooled. In the second mode, the motor operates at a second energy efficiency lower than the first energy efficiency for the given set torque. Thus, additional heat is generated by the motor's thermal losses.Furthermore, in the second mode, the heat transfer fluid circulates in the second circuit, but it is not cooled. Consequently, in this second mode, the heat transfer fluid carries the heat generated by the engine to the battery. Thus, the battery operates more efficiently at low temperatures.

[0004] However, due to its thermal inertia, the motor heats up during an initial transient period before reaching a set thermal power. This initial transient period is longer than the subsequent transient heating time of a heating element. To illustrate this, the initial transient period is on the order of 7 minutes, while the subsequent transient period is generally less than 1 minute. Consequently, the device is not very responsive to the given instructions.

[0005] The objective of the invention is to overcome the disadvantages of the prior art by proposing a method offering increased responsiveness to instructions, while saving vehicle energy and presenting reduced manufacturing costs.

[0006] To this end, the invention relates to a method for thermoregulating a heat transfer circuit of an electric or hybrid vehicle, the heat transfer circuit comprising: - a motor exhibiting a rotational speed and a motor torque; - a battery exhibiting a voltage; - an inverter electrically connecting the battery to the motor, the inverter having a switching frequency; and, - a pump capable of circulating a heat transfer fluid in the heat transfer circuit between the battery, the engine and the inverter, The thermoregulation process includes the following steps: - a step of measuring a motor rotation speed value, a motor torque value, and a voltage value; - a calculation step, by averaging a thermal power set between a first instant and a second instant, of a first average value of thermal power dissipated by the whole of the motor and the inverter, the second instant being subsequent to the first instant; - a calculation step, by averaging the thermal power recorded between the first instant and a third instant, of a second average value of thermal power dissipated by the entire motor and inverter, the third instant being prior to the second instant; - a step to calculate the value of thermal power dissipated by the engine, denoted Pm, using the following formula: Pm - f(C, v, PI, U)QU f is a first function determined by a first predetermined mapping, the first function f presenting input variables including the measured motor torque value, denoted C, the measured motor rotation speed value, denoted v, the first calculated average thermal power value, denoted PI, and the measured voltage value, denoted U; - a step to calculate the value of thermal power dissipated by the inverter, denoted Po, using the following formula: Po = P2 - Pm where P2 is the second average value of thermal power calculated and Pm is the value of thermal power dissipated by the engine calculated; - a step of calculating a first value of thermal power dissipated by the inverter, denoted Pol, using the following formula: Po\ - ^C, v, Fl)°ù g is a second function determined by a second predetermined mapping, the second function g presenting input variables including the measured motor torque value, denoted C, the measured motor rotation speed value, denoted v, and a first predetermined switching frequency value, denoted Fl; - a step of calculating a second value of thermal power dissipated by the inverter, denoted Po2, using the following formula: Po2 = ^C, v, F2) or the input variables of the second function g include the measured motor torque value, denoted C, the measured rotational speed value, denoted v, and a second predetermined switching frequency value, denoted F2, such that: F2 <Fl- une étape de calcul d’une valeur de fréquence de commutation consigne de l’onduleur correspondant à la valeur de puissance thermique dissipée par l’onduleur, à partir d’une interpolation basée sur la première valeur de puissance thermique dissipée par l’onduleur calculée pour la première valeur de fréquence prédéterminée et sur la deuxième valeur de puissance thermique dissipée par l’onduleur calculée pour la deuxième valeur de fréquence prédéterminée ; - a step to update the inverter switching frequency value, replacing it with the inverter's setpoint switching frequency value.

[0007] Thus, the delay between the setpoint regulations and the battery heating is reduced while reusing the heat generated by the motor and the inverter. Furthermore, this process avoids the need for a heating element to heat the battery. Consequently, on the one hand, the vehicle's manufacturing cost is reduced. On the other hand, this contributes to reducing the vehicle's energy consumption.

[0008] Advantageously, the ratio of the first predetermined switching frequency value to the second predetermined switching frequency value is between 1 and 5.

[0009] Such a ratio ensures flexibility in the heat production of the inverter while preserving the inverter from premature wear.

[0010] Advantageously, the ratio of the difference between the first instant and the second instant to the difference between the first instant and the third instant is between 1 and 10.

[0011] This ratio is chosen so as to distinguish rapid fluctuations in the set thermal power while providing sufficient responsiveness to rapid changes in thermal conditions.

[0012] Advantageously, the thermoregulation method includes, between the calculation step by interpolation and the update step, a step of substituting the setpoint switching frequency value with the following value: min(max(F, F2), F1)°where F' is the calculated setpoint switching frequency, Fl is the first predetermined frequency and F2 is the second predetermined frequency.

[0013] The switching frequency is limited so as to avoid premature wear of the inverter.

[0014] The invention also relates to a computer program comprising program code instructions for executing the steps of the thermoregulation process of a heat transfer circuit as defined above.

[0015] The invention further relates to an assembly comprising an electrical circuit and an electronic control unit including means for acquisition, processing by software instructions stored in a memory and control means configured for the implementation of the computer program defined as above.

[0016] The invention also relates to an electric or hybrid vehicle comprising an assembly as defined above.

[0017] An embodiment of the present invention will be described below by way of non-limiting examples, with reference to the accompanying figures in which: - [Fig.l] is a schematic representation of a heat transfer circuit according to the state of the art; - [Fig.2] is a flowchart representing a thermoregulation process for the heat transfer circuit, illustrated in [Fig.1], according to an embodiment of the invention.

[0018] Fig. 1 illustrates a heat transfer circuit 10 comprising a battery 12, a pump 14, an inverter 13, and a motor 11. The heat transfer circuit 10 is a network of pipes passing through the battery 12, the pump 14, the inverter 13 and the motor 11.

[0019] A heat transfer fluid circulates in the pipe of the heat transfer circuit 10. In this way, the heat transfer fluid receives by thermal conduction thermal power generated by the motor 11 and the inverter 13.

[0020] The heat transfer fluid is preferably glycol water. Thus, the heat transfer fluid is less likely to freeze in the heat transfer circuit 10 under low temperature conditions.

[0021] The motor 11 includes a first fluid inlet and a first fluid outlet. The inverter 13 includes a second fluid inlet and a second fluid outlet.

[0022] In [Fig. 1], a fluid outlet from the battery 12 is connected to a fluid inlet of the pump 14 via the heat transfer circuit 10. Furthermore, a fluid outlet from the pump 14 is connected to the first fluid inlet via the heat transfer circuit 10. In addition, the first fluid outlet is connected to the second fluid inlet via the circuit heat transfer fluid 10. In addition, the second fluid outlet is connected to a fluid inlet of the battery 12 via the heat transfer fluid circuit 10.

[0023] According to an unillustrated variant, the pump's fluid outlet is connected to the first fluid inlet and the second fluid inlet via the heat transfer circuit 10. In addition, the first fluid outlet and the second fluid outlet are connected to the fluid inlet of the coil 12 via the heat transfer circuit 10.

[0024] In this way, the heat transfer fluid is not heated by the inverter 13 before passing through the motor 11. Thus, the heat transfer fluid can more efficiently capture heat from the inverter 13 and the motor 11. Consequently, the battery 12 is heated more.

[0025] According to another variant not shown, the heat transfer circuit 10 is in contact with an air conditioning circuit of the vehicle. Thus, the vehicle's passenger compartment recovers the heat generated in the heat transfer circuit 10. In this way, the vehicle is heated more economically.

[0026] The pump 14 imposes a given flow rate on the heat transfer fluid. Thus, the motor 11 and the inverter 13 generate thermal power transported by the heat transfer fluid in the heat transfer circuit 10. In particular, this thermal power is received by the coil 12. Thus, the coil 12 is heated.

[0027] The inverter 13 electrically connects the battery 12 to the motor 11. The inverter 13 has a switching frequency.

[0028] An electronic control unit, not illustrated, includes a computer electrically connected to the motor 11 and the inverter 13.

[0029] The motor 11 comprises a motor shaft having a rotational speed and a motor torque. Furthermore, the battery 12 has a voltage across its terminals.

[0030] According to one embodiment, the thermoregulation process comprises the steps described below and illustrated in [Fig. 2]. The computer is capable of implementing the steps of the thermoregulation process.

[0031] In a measurement step El, a motor speed value, a motor torque value, and a voltage value are measured. The sampling frequency of these measurements is preferably on the order of 100 ms.

[0032] In a calculation step E2, a first average value of thermal power dissipated by the entire motor 11 and inverter 13, denoted PI, is calculated using the following moving average formula: ff2P(r) j °where P(r) is a value of a setpoint thermal power taken at At a given instant r, t1 is a value of a first instant, t2 is a value of a second instant. The second instant is later than the first instant.

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[0044] For example, a value for a first time interval between the first instant and the second instant is approximately 10 minutes. For example, the first average value of thermal power dissipated by the entire motor 11 and inverter 13 is 3 kW. In calculation step E3, a second average value of thermal power dissipated by the entire motor 11 and inverter 13 assembly, denoted P2, is calculated by the Calculator using the following moving average formula: p2 = )tiÂt2dl where P(r) is the value of the setpoint thermal power taken at a instantr, tl is the first instant, ^3 is a third instant. The third instant is prior to the second instant. For example, a value for a second time interval between the first instant and the third instant is approximately 1 minute. For example, the second average value of thermal power dissipated by the whole of the motor 11 and inverter 13, calculated by the calculator, is 3.8 kW. Depending on the variant, the first average value of thermal power or the second average value of thermal power is calculated by a simple moving average, or by a weighted moving average, or by any other type of sliding average. Preferably, calculation step E2 for the first average thermal power value and calculation step E3 for the second average thermal power value are performed in parallel. This reduces the calculation time for the thermoregulation process. According to one variant, calculation step E2 and calculation step E3 are carried out one after the other. In calculation step E4, a value of thermal power dissipated by the motor 11, denoted Pm, is calculated using the following formula: Pm - f (C, v, PI, U) where f is a first function determined by a first predetermined mapping described below. In this formula, the first function has input variables including the measured motor torque value, denoted C, the measured motor speed value, denoted v, the first calculated average thermal power value, denoted PI, and the measured voltage value, denoted U For example, the value of thermal power dissipated by motor 11, calculated by the computer, is 2 kW. In general, the first mapping is predetermined by a first experimental design determining a discrete domain of definition for each of the input variables of the first function.

[0045] For example, the motor torque definition range includes values ​​from 10 Nm to 1000 Nm. The rotational speed definition range includes values ​​from 600 RPM to 6000 RPM. The thermal power definition range includes values ​​from 5 kW to 100 kW. The voltage definition range includes values ​​from 100 W to 800 W.

[0046] In this case, when a test is carried out, a value of thermal power dissipated by the motor 11 is measured by fixing the values ​​of input variables, within their respective domain of definition, including a given value of motor torque, a given value of rotational speed, a given value of voltage and a given value of thermal power dissipated by the whole of the motor and inverter.

[0047] Thus, the values ​​of thermal power dissipated by the engine 11 measured during tests form a map with the associated values ​​of the input variables.

[0048] The values ​​of thermal power dissipated by the engine 11 are preferably measured by experimental tests.

[0049] According to one variant, the mapping is predetermined by tests obtained by simulation.

[0050] The first function preferably has a linear form with respect to each of its input variables. Such a function form has the advantage of being simple to model while remaining sufficiently representative of the measured values. Thus, the first function is determined by multilinear regression from the first mapping.

[0051] Depending on variants, depending on its form, the first function is determined from the first mapping, by polynomial regression, by machine learning or by any other regression.

[0052] In a calculation step E5, a value of thermal power dissipated by the inverter 13, denoted Po, is calculated using the following formula: Po = P2 - Pm where P2 is the second average value of thermal power calculated and Pm is the value of thermal power dissipated by the motor calculated.

[0053] Using the values ​​from the previous examples, the value of thermal power dissipated by the inverter 13, calculated by the calculator, is 1.8 kW.

[0054] In a calculation step E6, a first value of thermal power dissipated by the inverter 13, denoted Pol, is calculated using the following formula: Poi = g(c. v, F l)°où g is a second function determined by a second mapping described below.

[0055] In this formula, the second function has input variables including the measured motor torque value, denoted C, the measured motor rotation speed value, denoted v and a first predetermined switching frequency value, denoted Fl.

[0056] For example, for a first switching frequency of 12 kHz, the first value of thermal power dissipated by the inverter 13, calculated by the calculator, is 1.4 kW.

[0057] In general, the second mapping is predetermined by a second experimental design determining a discrete domain of definition for each of the input variables of the second function.

[0058] For example, the motor torque definition range includes values ​​from 10 Nm to 1000 Nm. The rotational speed definition range includes values ​​from 600 RPM to 6000 RPM. The switching frequency definition range includes values ​​from 2 kHz to 30 kHz.

[0059] In this case, when a test is carried out, a value of thermal power dissipated by the inverter 13 is measured by fixing the values ​​of input variables, within their respective domain of definition, including a given value of motor torque, a given value of rotational speed, and a given value of switching frequency.

[0060] Thus, the values ​​of the thermal power dissipated by the inverter 13 measured during tests form a map with the associated values ​​of the input variables.

[0061] The values ​​of thermal power dissipated by the inverter are preferably measured by experimental tests.

[0062] According to one variant, the mapping is predetermined by tests obtained by simulation.

[0063] The second function preferably has a linear form with respect to each of its input variables. Such a function form has the advantage of being simple to model while remaining sufficiently representative of the measured values. Thus, the second function is determined by multilinear regression from the second mapping.

[0064] Depending on variants, depending on its form, the second function g is determined from the second mapping, by polynomial regression, by machine learning or by any other regression.

[0065] In a calculation step E7, a second value of thermal power dissipated by the inverter 13, denoted Po2, is calculated using the following formula: Po2 - g(C, v, F2)°where g is the second function determined by the second predetermined mapping.

[0066] In this formula, the second function has input variables including the measured motor torque value, denoted C, the measured motor rotation speed value, denoted v and a second predetermined switching frequency value, denoted F2.

[0067] For example, for a second switching frequency of 20 kHz, the second value of thermal power dissipated by the inverter 13, calculated by the calculator, is 2 kW.

[0068] The second predetermined switching frequency value is chosen to be lower than the first predetermined switching frequency value.

[0069] Preferably, the calculation step E6 of the first value of thermal power dissipated by the inverter 13 and the calculation step E7 of the second value of thermal power dissipated by the inverter 13 are calculated in parallel. In this way, the calculation time of the thermoregulation process is shorter.

[0070] According to one variant, calculation step E6 and calculation step E7 are carried out one after the other.

[0071] In a calculation step E8, a setpoint switching frequency value of the inverter 13, denoted F', is calculated using the following linear interpolation formula: F-=(.Po-Po2)^^+F2

[0072] Using the values ​​from the previous examples, the setpoint switching frequency value F' is approximately 17.33 kHz.

[0073] According to variants, the setpoint switching frequency is calculated by any other interpolation formula.

[0074] In an update step E9, the switching frequency value of inverter 13 is substituted by the setpoint switching frequency value of inverter 13.

Claims

1. Demands Method for thermoregulating a heat transfer circuit (10) of an electric or hybrid vehicle, the heat transfer circuit (10) comprising: - a motor (11) having a rotational speed and a motor torque; - a battery (12) presenting a voltage; - an inverter (13) electrically connecting the battery (12) to the motor (11), the inverter (13) having a switching frequency; and, - a pump (14) capable of circulating a heat transfer fluid (10) in the heat transfer circuit (10) between the battery (12), the motor (11) and the inverter (13), the thermoregulation process comprising the following steps: - a measurement step (El) of a motor rotation speed value, a motor torque value, and a voltage value; - a calculation step (E2), by averaging a thermal power set between a first instant and a second instant, of a first average value of thermal power dissipated by the whole of the motor (11) and the inverter (13), the second instant being subsequent to the first instant; - a calculation step (E3), by averaging the thermal power recorded between the first instant and a third instant, of a second average value of thermal power dissipated by the whole of the motor (11) and the inverter (13), the third instant being prior to the second instant; - a calculation step (E4) of a value of thermal power dissipated by the motor, denoted Pm, by the following formula: Pm = f(C. v. Pï, Ù)°where f is a first function determined by a first predetermined mapping, the first function f presenting input variables including the measured motor torque value, denoted C, the measured motor rotation speed value, denoted v, the first average calculated thermal power value, denoted PI, and the measured voltage value, denoted U; - a calculation step (E5) of a value of thermal power dissipated by the inverter (13), denoted Po, by the following formula: Po = P2-Pm where P2 is the second average value of thermal power calculated and Pm is the value of thermal power dissipated by the engine calculated; - a calculation step (E6) of a first value of thermal power dissipated by the inverter (13), denoted Pol, using the following formula: Pol = ^C, v, Fl)where g is a second function determined by a second predetermined mapping, the second function g having input variables including the measured motor torque value, denoted C, the measured motor rotation speed value, denoted v, and a first predetermined switching frequency value, denoted Fl; - a calculation step (E7) of a second value of thermal power dissipated by the inverter (13), denoted Po2, using the following formula: Po2 = g(C, v, F2) where the input variables of the second function g include the measured motor torque value, denoted C, the measured rotational speed value, denoted v, and a second predetermined switching frequency value, denoted F2, such that: F2 <F1- une étape de calcul (E8) d’une valeur de fréquence de commutation consigne de l’onduleur (13) correspondant à la valeur de puissance thermique dissipée par l’onduleur (13), à partir d’une interpolation basée sur la première valeur de puissance thermique dissipée par l’onduleur calculée pour la première valeur de fréquence prédéterminée et sur la deuxième valeur de puissance thermique dissipée par l’onduleur calculée pour la deuxième valeur de fréquence prédéterminée ; - an update step (E9) of the inverter switching frequency value (13), replacing it with the inverter setpoint switching frequency value (13).

2. Thermoregulation method according to claim 1, characterized in that the ratio of the first predetermined switching frequency value to the second predetermined switching frequency value is between 1 and 5.

3. Thermoregulation method according to claim 1 or 2, characterized in that the ratio of the difference between the first instant and the second instant on the difference between the first instant and the third instant is between 1 and 10.

4. Thermoregulation method according to any one of claims 1 to 3, characterized in that the thermoregulation method comprises, between the calculation step (E8) by interpolation and the update step (E9), a step of substituting the setpoint switching frequency value of the inverter (13) with the following value: min(niñx(F, F2), Fl)° where F' is the calculated setpoint switching frequency, Fl is the first predetermined frequency and F2 is the second predetermined frequency.

5. Computer program comprising program code instructions for performing the steps of the thermoregulation process according to any one of claims 1 to 4, when said program is running on a computer.

6. Assembly comprising an electrical circuit and an electronic control unit including means for acquisition, processing by software instructions stored in memory and control means configured for the implementation of the computer program according to claim 5.

7. Electric or hybrid vehicle comprising an assembly according to claim 6.