Method for controlling a thermal conditioning system for a motor vehicle

Abstract

The invention relates to a method for controlling a thermal conditioning system (100) for a motor vehicle, the thermal conditioning system (100) having a refrigerant fluid circuit (10) comprising a first heat exchanger (1) configured to supply thermal power to an interior air flow (Fi), a heat-transfer liquid circuit (20) successively comprising a device (15) for heating the heat-transfer liquid, a second heat exchanger (2) arranged jointly on the refrigerant fluid circuit (10), and a battery (25), the method comprising: activating the heating device (15), receiving a target thermal power to be supplied to the battery (25), receiving a maximum thermal power that can be supplied to the refrigerant fluid in the second heat exchanger (2), the method further comprising: controlling a temperature difference of the heat-transfer liquid between the inlet (2c) and the outlet (2d) of the second exchanger (2) such that the thermal power supplied to the battery (25) is equal to the target thermal power, and the thermal power supplied to the refrigerant fluid in the second exchanger (2) is lower than the maximum thermal power.

Description

[0001] Description

[0002] Title: Method for controlling a thermal conditioning system

[0003] technical field

[0004] [1] The present invention relates to the field of thermal conditioning systems. Such systems can, for example, be fitted to motor vehicles. These systems ensure thermal regulation of various vehicle components, such as the passenger compartment or an electrical energy storage battery, when the vehicle is electrically powered. Heat exchange is managed primarily by the compression and expansion of a refrigerant circulating in a circuit containing several heat exchangers. A compressor forces the refrigerant into a high-pressure state and allows its circulation within the circuit.

[0005] Previous technique

[0006] [2] It is known to circulate a heat transfer fluid around a component of a vehicle's powertrain, this component being a battery for storing electrical energy. The heat transfer fluid circuit may include a heat exchanger arranged alongside the refrigerant circuit; this heat exchanger may, under certain operating conditions, function as a refrigerant evaporator. The heat transfer fluid is thus cooled, and the circulation of the cooled heat transfer fluid through the battery cools the battery.

[0007] The heat transfer fluid circuit may also include an electric heater which, depending on other operating modes, heats the heat transfer fluid. The circulation of hot heat transfer fluid heats this coil.

[0008] [3] In a specific operating mode, the heat extracted from the heat transfer fluid at the aforementioned refrigerant evaporator increases the heating capacity of the vehicle's passenger compartment. This is because an increase in the amount of fluid evaporated increases the amount of refrigerant that can be condensed. [4] In operating modes where both the vehicle's passenger compartment and the electrical energy storage battery must be heated simultaneously, managing the distribution of heating power between the passenger compartment and the battery can be challenging.

[0009] [5] The proposed process aims to improve the situation.

[0010] Summary

[0011] [6] To this end, a method for controlling a thermal conditioning system for a motor vehicle is proposed, the thermal conditioning system comprising:

[0012] - a refrigerant circuit configured to circulate a refrigerant, the refrigerant circuit comprising a first heat exchanger configured to provide thermal power to an internal airflow,

[0013] - a heat transfer fluid circuit configured to circulate a heat transfer fluid, the heat transfer fluid circuit comprising successively, according to a direction of heat transfer fluid circulation:

[0014] -- a device for heating the heat transfer fluid,

[0015] -- a second heat exchanger arranged jointly on the refrigerant circuit and on the heat transfer fluid circuit, the second heat exchanger being configured to allow heat exchange between the refrigerant and the heat transfer fluid, the second exchanger having a heat transfer fluid inlet and a heat transfer fluid outlet,

[0016] the second heat exchanger being configured to evaporate at least some of the refrigerant from the first heat exchanger,

[0017] -- a component of the vehicle's electric powertrain,

[0018] the process comprising:

[0019] (i) activate the heating device so as to supply thermal power to the heat transfer fluid,

[0020] (ii) receive a target thermal power to be supplied to the traction chain element by the heat transfer fluid,

[0021] (iii) receive the maximum thermal power that can be supplied to the refrigerant by the heat transfer fluid in the second heat exchanger, (iv) circulate heat transfer fluid in the heat transfer fluid circuit so as to supply thermal power to the refrigerant in the second heat exchanger and to supply thermal power to the traction chain element, and comprising:

[0022] (v) control a temperature difference of the heat transfer fluid between the inlet and outlet of the second heat exchanger such that:

[0023] - the thermal power supplied to the traction chain element by the heat transfer fluid is equal to the target thermal power, and

[0024] - the thermal power supplied to the refrigerant in the second heat exchanger is less than or equal to the maximum thermal power that can be supplied in the second heat exchanger.

[0025] [7] The thermal power supplied by the heating device is used both to evaporate the refrigerant in the second heat exchanger and to heat the upstream traction chain element. In other words, the heat from the heat transfer fluid is shared between the need for refrigerant evaporation and the need to heat the traction chain element. The proposed process sets a maximum value for the thermal power that the refrigerant can receive from the heat transfer fluid at the second heat exchanger. The proposed process controls the temperature drop of the heat transfer fluid as it passes through the second heat exchanger, so as to limit, if necessary, the thermal power received by the refrigerant to the set maximum value.Unlike known systems, the proposed process makes it possible to limit the thermal power taken from the heat transfer fluid by the evaporation of the refrigerant, so that the element of the traction chain receives the expected thermal power.

[0026] [8] The features listed in the following paragraphs can be implemented independently of each other or in any technically possible combination:

[0027] [9] The first heat exchanger is thermally coupled with an interior airflow to a vehicle passenger compartment. The first exchanger is configured to provide thermal power to the interior airflow.

[0028]

[0010] The first exchanger is configured to operate as a high-pressure refrigerant condenser or high-pressure refrigerant cooler, so as to heat the indoor airflow.

[0011] The second exchanger is configured to operate as a low-pressure refrigerant evaporator so as to transfer thermal power from the heat transfer fluid to the refrigerant.

[0029]

[0012] The heating device is a device for heating the heat transfer fluid.

[0030]

[0013] The heating device is configured to provide thermal power to the heat transfer fluid.

[0031]

[0014] The heat transfer fluid heating device is an electric heater.

[0032]

[0015] According to one embodiment, the element of the vehicle's electric powertrain includes an electrical energy storage battery.

[0033]

[0016] Alternatively or in addition, the element of the vehicle's electric drive chain includes an electric vehicle traction motor.

[0034]

[0017] Alternatively or in addition, the element of the vehicle's electric traction chain includes an electronic control unit for the vehicle's electric traction motor.

[0035]

[0018] According to certain operating modes of the thermal conditioning system, the element of the vehicle's electric powertrain can be cooled.

[0036]

[0019] According to other operating modes of the thermal conditioning system, the element of the vehicle's electric drive chain can be heated.

[0037]

[0020] According to one aspect of the proposed control method, the method comprises:

[0038] - receive a target thermal power to be supplied to the indoor airflow in the first exchanger,

[0039] in which the thermal power supplied to the indoor airflow in the first exchanger is less than or equal to the target thermal power to be supplied to the indoor airflow in the first exchanger.

[0040]

[0021] The proposed method ensures that the traction chain element receives the expected thermal power, thus heating it at the expected rate. However, when the thermal power of the heat transfer fluid heating device is insufficient to jointly provide the setpoint thermal power for both the second heat exchanger and the traction chain element, the actual thermal power supplied to the internal airflow may be lower than the setpoint value.

[0041]

[0022] According to one embodiment of the proposed control method, in which the refrigerant circuit comprises a compressor configured to deliver a high-pressure refrigerant flow, the compressor having a rotational speed,

[0042] The step of controlling the temperature difference of the heat transfer fluid between the inlet and outlet of the second heat exchanger includes the following sub-steps:

[0043] - reduce the compressor speed if the temperature difference of the heat transfer fluid between the inlet and outlet of the second heat exchanger exceeds a target value,

[0044] - increase the compressor rotation speed if the temperature difference of the heat transfer fluid between the inlet and outlet of the second exchanger is less than the target value.

[0045]

[0023] All other parameters remaining constant, the pressure at the inlet of the compressor is a decreasing function of the compressor's rotational speed.

[0046] Increasing the compressor speed decreases the pressure at the compressor inlet. Conversely, decreasing the compressor speed increases the pressure at the compressor inlet. The pressure at the compressor inlet is approximately the same as the pressure at the outlet of the second heat exchanger. Therefore, the compressor speed controls the evaporation temperature of the refrigerant in the second heat exchanger, and thus the temperature difference of the heat transfer fluid between the inlet and outlet of the second heat exchanger.

[0047]

[0024] The compressor is a centrifugal compressor.

[0048]

[0025] The flow rate of refrigerant discharged by the compressor depends on the compressor's rotation speed.

[0049]

[0026] The compressor is an electric compressor.

[0050]

[0027] The compressor's rotation speed can be controlled by the electric current supplying the compressor's electric motor.

[0028] The refrigerant flow rate discharged by the compressor can vary in real time.

[0051]

[0029] The heat transfer fluid circuit includes a circulation pump configured to circulate the heat transfer fluid in the circuit.

[0052]

[0030] The circulation pump is an electric pump.

[0053]

[0031] The flow rate of heat transfer fluid in the circuit can vary in real time.

[0054]

[0032] The flow rate of heat transfer fluid in the circuit depends on the rotation speed of the circulation pump.

[0055]

[0033] According to another aspect of the proposed process:

[0056] - the maximum thermal power that can be supplied to the refrigerant by the heat transfer fluid, in the second heat exchanger, depends on the thermal power supplied by the heating device to the heat transfer fluid.

[0057]

[0034] The value of the maximum thermal power parameter can thus be adapted in real time to the actual operating conditions.

[0058]

[0035] The thermal power supplied by the heating device can vary between zero power and maximum power.

[0059]

[0036] The thermal power supplied by the heating device can vary in real time.

[0060]

[0037] The maximum thermal power that can be supplied to the refrigerant by the heat transfer fluid, in the second heat exchanger, is equal to the difference between the thermal power supplied by the heating device and the target thermal power to be supplied to the traction chain element by the heat transfer fluid.

[0061]

[0038] According to one embodiment of the proposed process, the value of the maximum thermal power that can be supplied to the refrigerant by the heat transfer fluid is determined by the formula:

[0062]

[0039] [Math. 1]

[0063] P2_max = P 15 — C_P25

[0040] with:

[0064] P2_max: Maximum thermal power in the second heat exchanger, P15: Thermal power supplied by the heating device, and

[0065] C_P25: Target thermal power to be supplied to the traction chain element.

[0066]

[0041] According to one embodiment of the proposed method, in which the heating device is configured to provide maximum thermal output, the method comprises the step:

[0067] - increase the thermal power supplied by the heating device until the maximum thermal power is supplied to the heat transfer fluid.

[0068]

[0042] When the heating requirement is high, the power supplied by the heating device is increased, if necessary until the heating device supplies its maximum power.

[0069]

[0043] The maximum thermal power supplied to the heat transfer fluid is obtained when the heating device consumes its maximum electrical power.

[0070]

[0044] According to another aspect of the proposed process, the process comprises the steps: - determining a target thermal power to be supplied by the refrigerant to the internal airflow at the level of the first exchanger,

[0071] - determine the thermal power received by the refrigerant at the compressor,

[0072] - determine a target thermal power to be supplied to the refrigerant at the second heat exchanger, the target thermal power being equal to the difference between the target thermal power to be supplied by the refrigerant to the indoor airflow at the first heat exchanger and the thermal power received by the refrigerant at the compressor,

[0073] - determine a corrected target thermal power to be supplied to the refrigerant at the heat exchanger, the corrected target thermal power being equal to the minimum value between the determined target thermal power and the maximum thermal power in the second exchanger.

[0074]

[0045] When the corrected target thermal power differs from the target thermal power, the thermal power actually supplied to the interior airflow at the first heat exchanger is less than the target thermal power. The passenger compartment temperature rise is slower than required by the setpoint, so as to leave sufficient thermal power to heat the component. Meeting the heating setpoint for the powertrain component takes priority over meeting the passenger compartment heating setpoint when both setpoints cannot be met simultaneously.

[0075]

[0046] The corrected target thermal power to be supplied to the refrigerant at the second heat exchanger is determined by the formula:

[0076] [Math. 2]

[0077] C_P2_cor = min(C_P2 , P2_max)

[0078]

[0047] with:

[0079] C_P2_cor: Corrected target thermal power,

[0080] C_P2: Target thermal power determined,

[0081] P2_max: Maximum thermal power in the second exchanger.

[0082]

[0048] According to an example of implementation of the proposed process, the value of the target thermal power to be supplied by the refrigerant to the indoor airflow at the level of the first exchanger is equal to the product of the flow rate of the indoor airflow, the heat capacity of the indoor airflow and the difference between the target temperature of the indoor airflow at the outlet of the first exchanger and the temperature of the indoor airflow at the inlet of the first exchanger.

[0083]

[0049] The value of the target thermal power to be supplied by the refrigerant to the internal airflow at the level of the first heat exchanger is thus determined by the formula:

[0084] [Math. 3]

[0085] C_P1 = Q_Fi * cpFi * (C.Tlfi - TOFi)

[0086]

[0050] with:

[0087] C_P1: Target thermal power to be supplied at the first heat exchanger, Q_Fi: Flow rate of the indoor air heated by the first heat exchanger.

[0088] cpFi: Heat capacity of the indoor airflow,

[0089] C_T1 fi: Target temperature of the indoor airflow at the outlet of the first heat exchanger, TOFi: Temperature of the indoor airflow at the inlet of the first heat exchanger.

[0051] According to one embodiment, the thermal conditioning system includes a fan-motor unit configured to provide an indoor airflow rate at the first heat exchanger, and

[0090] The flow rate of the indoor air heated by the first exchanger is determined from a control voltage of the motor-fan unit.

[0091]

[0052] Alternatively, the flow rate of the interior air heated by the first exchanger is determined from a control voltage of the motor-fan unit and from the forward speed of the vehicle.

[0092]

[0053] According to one embodiment, the thermal power received by the refrigerant at the compressor is determined from the electrical power absorbed by the compressor and from a correction coefficient.

[0093]

[0054] For example, the thermal power received by the refrigerant at the compressor is equal to the electrical power absorbed by the compressor multiplied by a correction coefficient.

[0094]

[0055] The thermal power received by the refrigerant at the compressor is thus determined by the formula:

[0095]

[0056] [Math. 4]

[0096] P7 = PE7 * K

[0097]

[0057] with:

[0098] P7: Thermal power received by the refrigerant at the compressor, PE7: Electrical power absorbed by the compressor.

[0099] K: Correction coefficient.

[0100]

[0058] According to one embodiment, the correction coefficient is determined as a function of the compressor's rotational speed.

[0101]

[0059] The correction coefficient can also be determined as a function of the compressor's rotational speed and as a function of the flow rate delivered by the compressor.

[0102]

[0060] According to an example of implementation of the proposed process, the process comprises the following steps:

[0103] - Determine the temperature of the heat transfer fluid at the inlet of the second heat exchanger, - Determine the flow rate of the heat transfer fluid in the second heat exchanger.

[0104] - determine a target temperature of the heat transfer fluid at the outlet of the second heat exchanger based on the temperature of the heat transfer fluid at the inlet of the second heat exchanger, the corrected target thermal power to be supplied to the refrigerant at the level of the second heat exchanger, and the flow rate of heat transfer fluid in the second heat exchanger,

[0105] - reduce the compressor speed if the temperature of the heat transfer fluid at the outlet of the second heat exchanger is lower than the target temperature of the heat transfer fluid at the outlet of the second heat exchanger.

[0106] - increase the compressor rotation speed if the temperature of the heat transfer fluid at the outlet of the second exchanger is higher than the target temperature of the heat transfer fluid at the outlet of the second exchanger.

[0107]

[0061] Using the temperature of the heat transfer fluid at the outlet of the second exchanger as an input parameter for regulation allows for simple and precise control.

[0108]

[0062] The process comprises the substep:

[0109] - determine a heat capacity of the heat transfer fluid in the second exchanger.

[0110]

[0063] According to one aspect of the proposed process, the target temperature of the heat transfer fluid at the outlet of the second exchanger is equal to the difference between:

[0111] - the temperature of the heat transfer fluid at the inlet of the second heat exchanger, and - the ratio of:

[0112] -- the corrected target thermal power to be supplied to the refrigerant at the level of the second heat exchanger, and the

[0113] -- product of the flow rate of the heat transfer fluid in the second exchanger and the heat capacity of the heat transfer fluid in the second exchanger.

[0114]

[0064] The use of a physical model of heat exchange in the second exchanger allows for rapid and precise regulation.

[0115]

[0065] The target temperature of the heat transfer fluid at the outlet of the second heat exchanger is thus determined by the equation:

[0116] [Math. 5]

[0117]

[0118]

[0066] with:

[0119] C_Tc2_out: Target temperature of the heat transfer fluid at the outlet of the second heat exchanger,

[0120] Tc2Jn: Temperature of the heat transfer fluid at the inlet of the second heat exchanger, C_P2_cor: Corrected target thermal power to be supplied to the refrigerant at the level of the second heat exchanger,

[0121] Q_c: Flow rate of heat transfer fluid in the second heat exchanger,

[0122] cpc: Heat capacity of the heat transfer fluid in the second exchanger.

[0123]

[0067] The flow rate of heat transfer fluid in the second exchanger is, for example, determined from a model based on the rotation speed of the circulation pump of the heat transfer fluid circuit.

[0124]

[0068] The rotation speed of the circulation pump of the heat transfer fluid circuit is, for example, determined by a rotation speed sensor of a shaft of the circulation pump.

[0125]

[0069] According to one embodiment, the proposed process comprises:

[0126] - determine the subcooling of the refrigerant at the outlet of the first heat exchanger,

[0127] - determine a target value for the subcooling of the refrigerant at the outlet of the first heat exchanger,

[0128] - control an effective passage area of ​​the first expansion valve so that the subcooling of the refrigerant at the outlet of the first exchanger is equal to the target value of the subcooling of the refrigerant at the outlet of the first exchanger.

[0129]

[0070] The expansion rate achieved by the first expansion valve allows the thermodynamic cycle to be optimized by adjusting the subcooling to a value that maximizes efficiency.

[0130]

[0071] The process comprises:

[0131] - if the subcooling of the refrigerant at the outlet of the first exchanger is less than the target value, decrease the effective passage area of ​​the first expansion valve.

[0132]

[0072] The process comprises:

[0133] - if the subcooling of the refrigerant at the outlet of the first exchanger is greater than the target value, increase the effective passage area of ​​the first expansion valve.

[0134]

[0073] The invention also relates to a thermal conditioning system comprising:

[0135] - a heat transfer fluid circuit configured to circulate a heat transfer fluid, - a refrigerant circuit configured to circulate a refrigerant, comprising a main refrigerant circulation loop comprising successively, according to a direction of refrigerant circulation:

[0136] - a compressor,

[0137] - a first heat exchanger thermally coupled with an airflow from inside a vehicle's passenger compartment,

[0138] - a first regulator,

[0139] - a second heat exchanger, jointly arranged on the refrigerant circuit and on the heat transfer fluid circuit, the second heat exchanger being configured to allow heat exchange between the refrigerant and the heat transfer fluid,

[0140] in which the heat transfer fluid circuit comprises successively, according to a direction of flow of the heat transfer fluid: a heat transfer fluid heating device, the second heat exchanger, an element of an electric traction system for the vehicle,

[0141] - an electronic control unit configured to implement the process described above.

[0142]

[0074] According to one embodiment, the first exchanger is configured to exchange heat with the airflow inside the vehicle's passenger compartment.

[0143]

[0075] According to one embodiment, the first exchanger is configured to exchange heat with a heat transfer fluid circulating in a closed heat transfer fluid circuit, the heat transfer fluid circuit comprising a heat exchanger configured to exchange heat with the airflow inside the vehicle's passenger compartment.

[0144]

[0076] According to one embodiment, the thermal conditioning system comprises a first bypass branch arranged in parallel with the first expansion valve and the second heat exchanger, the first bypass branch comprising successively:

[0145] -- a second regulator,

[0146] -- a third heat exchanger thermally coupled with an outside airflow.

[0147]

[0077] The third exchanger is configured to operate selectively as a refrigerant fluid evaporator or as a refrigerant fluid condenser.

[0148]

[0078] The first branch branch connects a first connection point located on the main loop downstream of the first heat exchanger and upstream of the first expansion valve to a second connection point located on the main loop downstream of the second heat exchanger and upstream of a compressor inlet, the first branch branch comprising successively a second expansion valve and a third heat exchanger thermally coupled with an outside air flow.

[0149]

[0079] According to one embodiment, the third heat exchanger is configured to exchange heat with the outside airflow to the vehicle's passenger compartment.

[0150]

[0080] According to one embodiment, the third heat exchanger is configured to exchange heat with a heat transfer fluid circulating in a closed heat transfer fluid circuit, the heat transfer fluid circuit comprising a heat exchanger configured to exchange heat with the outside airflow to the vehicle's passenger compartment.

[0151]

[0081] The main loop includes a refrigerant fluid accumulation device located downstream of the second connection point and upstream of a compressor inlet.

[0152]

[0082] According to one embodiment, the thermal conditioning system comprises a second bypass branch arranged in parallel with the first expansion valve and the second heat exchanger, the second bypass branch comprising successively:

[0153] -- a third regulator,

[0154] -- a fourth heat exchanger thermally coupled with the internal airflow.

[0155]

[0083] The fourth exchanger is configured to operate as a refrigerant fluid evaporator.

[0156]

[0084] The second branch branch connects a third connection point located on the main loop downstream of the first exchanger and upstream of the first connection point to a fourth connection point located on the main loop downstream of the second connection point and upstream of the compressor inlet, the second branch branch comprising successively a third expansion valve and a fourth heat exchanger thermally coupled with the internal airflow.

[0157]

[0085] According to one embodiment, the fourth exchanger is configured to exchange heat with the airflow inside the vehicle's passenger compartment.

[0158]

[0086] According to one embodiment, the fourth exchanger is configured to exchange heat with a heat transfer fluid circulating in a closed heat transfer fluid circuit, the heat transfer fluid circuit comprising a heat exchanger configured to exchange heat with the airflow inside the vehicle's passenger compartment.

[0159]

[0087] The invention also relates to a computer program stored in memory and configured to implement the process described above.

[0160] Brief description of the drawings

[0161]

[0088] Other features, details and advantages will become apparent upon reading the detailed description below, and upon analysis of the accompanying drawings, on which:

[0162]

[0089] [Fig. 1] is a schematic view of a first embodiment of a thermal conditioning system that can implement the proposed process,

[0163]

[0090] [Fig. 2] is a schematic view detailing certain internal variables used by the proposed process,

[0091] [Fig. 3] is a schematic view of a second embodiment of a thermal conditioning system that can implement the proposed process,

[0164]

[0092] [Fig. 4] is a schematic view of a variant of the thermal conditioning system of Figure 3,

[0165]

[0093] [Fig. 5] is a schematic view of the thermal conditioning system of Figure 1, illustrating the operation of the proposed process,

[0166]

[0094] [Fig. 6] is a block diagram of the proposed process.

[0167] Description of the implementation methods

[0168]

[0095] To facilitate reading the figures, the various elements are not necessarily drawn to scale. In these figures, identical elements bear the same reference numerals. Certain elements or parameters may be indexed, that is, designated, for example, as first element or second element, or first parameter and second parameter, etc. This indexing aims to differentiate similar, but not identical, elements or parameters. This indexing does not imply any priority of one element or parameter over another, and the designations may be interchanged.

[0169]

[0096] In the following description, the expression "a first element upstream of a second element" means that the first element is placed before the second element with respect to the direction of flow, or path, of a fluid. Similarly, the term "a first element downstream of a second element" means that the first element is placed after the second element with respect to the direction of flow, or path, of the fluid in question. In the case of a refrigerant circuit, in which the circulation of the refrigerant is achieved by means of a compressor, the term "a first element is upstream of a second element" means that the refrigerant flows successively through the first element, then the second element, without passing through the refrigerant compressor.In other words, the refrigerant exits the compression device, possibly passes through one or more elements, then passes through the first element, then the second element, then returns to the compressor inlet, possibly after passing through other elements.

[0097] The expression "a second element is placed between a first element and a third element" means that the shortest path to go from the first element to the third element passes through the second element.

[0170]

[0098] When it is specified that a subsystem includes a given element, this does not exclude the presence of other elements in that subsystem.

[0171]

[0099] The thermal conditioning system 100, which will be described below, comprises an electronic control unit 60 that receives information from various sensors measuring, in particular, the characteristics of the refrigerant at various points in the circuit. The electronic control unit 60 also receives instructions from the vehicle occupants, such as the desired temperature inside the passenger compartment. The electronic control unit 60 can also receive instructions from other electronic subsystems, such as the electrical energy storage battery management system. The electronic control unit 60 implements control laws to operate the various actuators, in order to control the thermal conditioning system 100 and ensure compliance with the received instructions.

[0172] In particular, control unit 60 can implement the proposed process.

[0173]

[0100] A compression device 7, also called a compressor 7, allows a refrigerant to circulate in a refrigerant circulation circuit 10. The refrigerant circuit 10 forms a closed circuit in which the refrigerant can circulate. The refrigerant circuit 10 is leak-proof when it is in a nominal operating state, that is, without any faults or leaks. Each connection point of the circuit 10 allows the refrigerant to pass into one or the other of the circuit sections connected to that connection point. The distribution of the refrigerant between the circuit sections connected at a connection point is achieved by opening or closing shut-off valves, check valves, or expansion devices located on each of these sections. In other words, each connection point is a means of redirecting the refrigerant arriving at that connection point.Various shut-off valves and check valves allow the refrigerant to be selectively directed into the different branches of the refrigerant circuit, in order to ensure different operating modes, as will be described later.

[0101] The refrigerant used by the refrigerant circuit 10 is a chemical refrigerant, such as R1234yf or R134a. A natural refrigerant, such as R290 or R744, can also be used.

[0174]

[0102] Each refrigerant expansion device, also called an expansion valve, can be an electronic expansion valve. In an electronic expansion valve, the passage area through which the refrigerant passes can be continuously adjusted between a closed position and a maximum open position. To achieve this, an electronic control module for the expansion valve drives an electric motor that moves a movable shutter, thus controlling the passage area available to the refrigerant.

[0175]

[0103] The term "interior airflow Fi" refers to an airflow directed towards the passenger compartment of the motor vehicle. This interior airflow Fi may circulate within a heating, ventilation, and / or air conditioning (HVAC) system. This system is not shown in the various figures. A first motor-fan unit, not shown, is located within the HVAC system to increase the flow rate of the interior airflow Fi if necessary.

[0176]

[0104] The term "external airflow Fe" refers to an airflow that is not directed towards the vehicle's passenger compartment. In other words, this airflow Fe remains outside the vehicle's passenger compartment. A second motor-fan unit, also not shown, can be activated to increase the flow rate of the external airflow Fe if necessary. The airflow provided by both the first and second motor-fan units can be adjusted in real time according to heat exchange requirements, for example, by the electronic control unit of the climate control system 100.

[0177]

[0105] The term "first exchanger" is equivalent to the term "first heat exchanger". Similarly, the term "internal exchanger" is equivalent to the term "internal heat exchanger". The term "storage device" is equivalent to the term "refrigerant storage device".

[0106] The heat transfer fluid circuit(s) also form one or more closed and sealed circuits in which a heat transfer fluid can circulate.

[0178]

[0107] Figure 1 shows a thermal conditioning system 100. The thermal conditioning system 100 comprises:

[0179] - a heat transfer fluid circuit 20 configured to circulate a heat transfer fluid,

[0180] - a refrigerant circuit 10 configured for circulating a refrigerant. The refrigerant circuit 10 comprises a main refrigerant circulation loop A, comprising successively, according to a direction of refrigerant flow:

[0181] - a 7-inch compressor,

[0182] - a first heat exchanger 1 thermally coupled with an internal airflow Fi to a vehicle passenger compartment,

[0183] - a first regulator 21,

[0184] - a second heat exchanger 2, jointly arranged on the refrigerant circuit 10 and on the heat transfer fluid circuit 20, the second heat exchanger 2 being configured to allow heat exchange between the refrigerant and the heat transfer fluid.

[0185] The heat transfer fluid circuit 20 comprises, successively according to the direction of heat transfer fluid circulation:

[0186] a heating device 15 for the heat transfer fluid, the second heat exchanger 2, an element 25 of an electric drive chain of the vehicle.

[0187] The thermal conditioning system 100 includes an electronic control unit 60 configured to implement the proposed process, which will be described in detail below.

[0188]

[0108] The thermal conditioning system 100 is here a thermal conditioning system for a motor vehicle.

[0189]

[0109] Thermal coupling between the first exchanger 1 and the internal airflow Fi can be ensured in different ways.

[0190] According to one embodiment, illustrated in particular in figure 1, the first exchanger 1 is configured to exchange heat with the interior airflow Fi to the vehicle's passenger compartment. The thermal coupling between the first exchanger 1 and the interior airflow Fi is then said to be direct.

[0191] The first heat exchanger 1 is located in the vehicle's heating, ventilation and / or air conditioning system.

[0192]

[0110] According to an alternative embodiment, illustrated in Figure 4, the first heat exchanger 1 is configured to exchange heat with a heat transfer fluid circulating in a closed heat transfer fluid circuit 30. The heat transfer fluid circuit 30 includes a heat exchanger 1A configured to exchange heat with the interior airflow Fi to the vehicle's passenger compartment.

[0193] The thermal coupling between the first exchanger 1 and the indoor airflow Fi is in this case said to be indirect.

[0194] The 1A exchanger, also known as the heater radiator, is located in the vehicle's heating, ventilation and / or air conditioning system.

[0195] The heat transfer fluid circuit 30 includes a circulation pump, not shown. The circulation pump is, for example, an electrically controlled pump and can be selectively switched on or off.

[0196]

[0111] According to one embodiment, element 25 of the vehicle's electric drivetrain comprises an electrical energy storage battery. According to a variant, or alternatively, element 25 of the vehicle's electric drivetrain comprises an electric vehicle traction motor.

[0197] Alternatively or in addition, element 25 of the vehicle's electric drive chain includes an electronic control unit for the vehicle's electric traction motor.

[0198]

[0112] The thermal conditioning system includes a first branch of bypass B arranged in parallel with the first expansion valve 21 and the second exchanger 2.

[0199] The first branch of derivation B comprises successively:

[0200] -- a second regulator 22,

[0201] -- a third heat exchanger 3 thermally coupled with an outside air flow Fe.

[0113] The first branch of the bypass B is arranged in parallel with a portion of the main loop A comprising in series the first expansion valve 21 and the second exchanger 2.

[0202] The third exchanger 3 is configured to operate selectively as a refrigerant fluid evaporator or as a refrigerant fluid condenser.

[0203]

[0114] More specifically, the first branch of derivation B connects:

[0204] - a first connection point 11 located on the main loop A downstream of the first exchanger 1 and upstream of the first pressure regulator 21 to

[0205] - a second connection point 12 located on the main loop A downstream of the second heat exchanger 2 and upstream of an inlet 7a of the compressor 7.

[0206] The first branch of the B branch includes successively a second expansion valve 22 and a third heat exchanger 3 thermally coupled with an outside air flow Fe.

[0207] The first branch branch B includes a one-way valve 41 located downstream of the third exchanger 3 and upstream of the second connection point 12. The one-way valve 41 allows refrigerant fluid to circulate through this one-way valve only from the third exchanger 3 to the second connection point 12.

[0208]

[0115] Thermal coupling between the third heat exchanger 3 and the outside airflow Fe can be ensured in different ways.

[0209] According to one embodiment, illustrated in particular in Figure 1, the third heat exchanger 3 is configured to exchange heat with the outside airflow Fe to the vehicle's passenger compartment.

[0210] This configuration corresponds to a direct thermal coupling between the third heat exchanger 3 and the outside airflow Fe.

[0211] The third heat exchanger 3 can be positioned at the front of the vehicle, for example, just behind the grille. The outside airflow Fe thus reaches the surface of the third heat exchanger 3 directly.

[0212] Alternatively, the third heat exchanger 3 can be located in a wheel arch.

[0116] According to one embodiment, illustrated in Figure 4, the third heat exchanger 3 is configured to exchange heat with a heat transfer fluid circulating in a closed heat transfer fluid circuit 40, the heat transfer fluid circuit 40 comprising a heat exchanger 3A configured to exchange heat with the outside airflow Fe to the vehicle's passenger compartment. The thermal coupling between the third heat exchanger 3 and the outside airflow Fe is, in this case, referred to as indirect.

[0213] The 3A intercooler, also known as the external radiator, is in this case located in the front of the vehicle, for example just behind the grille.

[0214] The heat transfer fluid circuit 40 includes a circulation pump, not shown. The circulation pump is, for example, an electrically controlled pump and can be selectively switched on or off.

[0215]

[0117] According to a second embodiment, illustrated in Figure 3, the refrigerant fluid circuit 10 includes an additional bypass branch.

[0216] The refrigerant fluid circuit 10 thus includes a second branch C arranged in parallel with the first expansion valve 21 and the second exchanger 2.

[0217] The second branch of derivation C comprises successively:

[0218] - a third regulator 23,

[0219] - a fourth heat exchanger 4 thermally coupled with the internal airflow Fi.

[0220]

[0118] The second branch of the bypass C is arranged in parallel with a portion of the main loop A comprising in series the first expansion valve 21 and the second exchanger 2.

[0221] The fourth exchanger 4 is configured to operate as a refrigerant fluid evaporator.

[0222]

[0119] The second branch of derivation C connects:

[0223] - a third connection point 13 arranged on the main loop A downstream of the first exchanger 1 and upstream of the first connection point 11 to - a fourth connection point 14 arranged on the main loop A downstream of the second connection point 12 and upstream of the inlet 7a of the compressor 7. The second branch C includes successively a third expansion valve 23 and a fourth heat exchanger 4 thermally coupled with the indoor air flow Fi.

[0224]

[0120] As before, the thermal coupling between the fourth heat exchanger 4 and the internal airflow Fi can be direct or indirect.

[0225] According to the embodiment shown in Figure 3, the fourth heat exchanger 4 is configured to exchange heat with the interior airflow Fi to the vehicle's passenger compartment. This fourth heat exchanger 4 is referred to as the passenger compartment evaporator and serves to cool the vehicle's passenger compartment.

[0226] This configuration corresponds to a direct thermal coupling.

[0227] The fourth exchanger 4 is located in the heating, ventilation and / or air conditioning system.

[0228]

[0121] The fourth heat exchanger 4 is arranged upstream of the first heat exchanger 1 according to a direction of flow of the indoor air flow Fi. In other words, the indoor air flow Fi first exchanges heat with the fourth heat exchanger 4 and then with the first heat exchanger 1.

[0229]

[0122] According to an alternative embodiment, illustrated in Figure 4, the thermal coupling between the fourth exchanger 4 and the internal airflow Fi is of the indirect type.

[0230] The fourth heat exchanger 4 is configured in this case to exchange heat with a heat transfer fluid circulating in a closed heat transfer fluid circuit 50. This circuit 50 includes a heat exchanger 4A configured to exchange heat with the interior airflow Fi to the vehicle's passenger compartment. According to this variant, the heat exchanger 4A is positioned upstream of the heat exchanger 1A, in the direction of the interior airflow Fi.

[0231]

[0123] According to the second embodiment, illustrated in Figure 3, the first exchanger 1, the third exchanger 3 and the fourth exchanger 4 all ensure direct thermal coupling.

[0232] According to one embodiment, illustrated in Figure 4, the first exchanger 1, the third exchanger 3 and the fourth exchanger 4 all provide indirect thermal coupling, involving exchangers 1A, 3A, 4A respectively. According to unrepresented variants, it is possible that some exchangers provide direct thermal coupling while other exchangers provide indirect thermal coupling.

[0233]

[0124] The proposed process will now be described. Figure 2 schematically indicates to which component of system 100 the different variables used by the proposed process apply.

[0234] These variables are represented by a dotted line ending in a dot.

[0235]

[0125] The proposed control method relates to a thermal conditioning system 100 for a motor vehicle, this thermal conditioning system 100 comprising:

[0236] - a refrigerant circuit 10 configured to circulate a refrigerant, the refrigerant circuit 10 comprising a first heat exchanger 1 configured to supply a thermal power P1 to an internal airflow Fi, - a heat transfer fluid circuit 20 configured to circulate a heat transfer fluid, the heat transfer fluid circuit 20 comprising successively, according to a direction of heat transfer fluid circulation:

[0237] -- a heating device 15 for the heat transfer fluid,

[0238] -- a second heat exchanger 2 arranged jointly on the refrigerant circuit 10 and on the heat transfer fluid circuit 20, the second heat exchanger 2 being configured to allow heat exchange between the refrigerant and the heat transfer fluid, the second heat exchanger 2 having a heat transfer fluid inlet 2c and a heat transfer fluid outlet 2d,

[0239] the second exchanger 2 being configured to evaporate at least part of the refrigerant fluid coming from the first exchanger 1,

[0240] -- an element 25 of an electric drivetrain of the vehicle.

[0241] The process includes:

[0242] (i) activate the heating device 15 so as to supply a thermal power P15 to the heat transfer fluid,

[0243] (ii) receive a target thermal power C_P25 to be supplied to element 25 of the traction chain by the heat transfer fluid,

[0244] (iii) receive a maximum thermal power P2_max that can be supplied to the refrigerant by the heat transfer fluid, in the second heat exchanger2,

[0245] (iv) to circulate heat transfer fluid in the heat transfer fluid circuit 20 so as to provide thermal power P2 to the refrigerant in the second exchanger 2 and to provide thermal power P25 to the traction chain element 25.

[0246] The proposed process also includes:

[0247] (v) control a temperature difference D2 of the heat transfer fluid between the inlet 2c and the outlet 2d of the second heat exchanger 2 such that:

[0248] - the thermal power P25 supplied to element 25 of the traction chain by the heat transfer fluid is equal to the target thermal power C_P25, and

[0249] - the thermal power P2 supplied to the refrigerant in the second heat exchanger 2 is less than or equal to the maximum thermal power P2_max that can be supplied in the second heat exchanger 2.

[0250]

[0126] A flow Q_r of high-pressure refrigerant fluid circulates in the refrigerant fluid circuit 10.

[0251] The proposed process thus includes a sub-step of activating the compressor 7, so as to circulate a flow of refrigerant fluid in the circuit 10.

[0252]

[0127] The thermal power supplied to the heat transfer fluid by the heating device 15 is used, on the one hand, to evaporate the low-pressure refrigerant circulating in the second heat exchanger 2, and on the other hand, to heat the component 25 of the powertrain located upstream of the heating device 15. In other words, the heat from the heat transfer fluid is shared between the need to evaporate the low-pressure refrigerant circulating in the second heat exchanger 2, and the need to heat the component 25 of the vehicle's electric powertrain. This component 25 can be, for example, an electrical energy storage battery. The proposed method sets a maximum value P2_max for the thermal power P2 that the refrigerant can receive from the heat transfer fluid at the second heat exchanger 2.The proposed method controls the temperature drop of the heat transfer fluid as it passes through the second heat exchanger 2, so as to limit, if necessary, the thermal power P2 received by the refrigerant. This thermal power P2 received by the refrigerant at the second heat exchanger 2 is limited to the fixed maximum value P2_max. Unlike known systems, the proposed method limits the thermal power extracted from the heat transfer fluid at the second heat exchanger 2 due to refrigerant evaporation. Situations in which the heat transfer fluid transfers too much heat to the refrigerant to subsequently provide sufficient thermal power to component 25 are avoided. With the proposed method, component 25 of the traction chain can always receive the expected thermal power, i.e., the target thermal power C-P25.

[0253]

[0128] The first heat exchanger 1 is thermally coupled with an interior airflow Fi to a vehicle passenger compartment. The first heat exchanger 1 is configured to provide a thermal power P1 to the interior airflow Fi.

[0254] The first exchanger 1 is configured to operate as a high-pressure refrigerant condenser or high-pressure refrigerant cooler, so as to heat the indoor airflow Fi.

[0255]

[0129] Indeed, the first heat exchanger 1 receives, when the compressor 7 is activated, a flow Q_r of refrigerant fluid at high pressure and high temperature. In the case of a two-phase refrigerant fluid, the refrigerant fluid condenses at least partially in the first heat exchanger 1, and the heat of condensation heats the internal airflow Fi.

[0256] In the case of a fluid in a supercritical state, the heating of the indoor airflow Fi takes place without condensation of the refrigerant fluid.

[0257]

[0130] The second exchanger 2 is configured to operate as a low-pressure refrigerant fluid evaporator so as to transfer thermal power from the heat transfer fluid to the refrigerant fluid.

[0258] The second exchanger 2 is located downstream of the first expansion valve 21, and can therefore receive a flow of low-pressure refrigerant fluid cooled after passing through the first exchanger 1.

[0259] The second heat exchanger 2 comprises a first heat exchange section configured for the flow of refrigerant, and a second heat exchange section configured for the flow of heat transfer fluid. Heat exchange can occur between the first and second heat exchange sections. The refrigerant and the heat transfer fluid can thus exchange heat.

[0260]

[0131] The thermodynamic cycle performed by the refrigerant is as follows: The refrigerant discharged at the outlet 7b of the compressor 7 condenses or cools in the first heat exchanger 1, which heats the internal airflow Fi. At least a portion of the refrigerant from the first heat exchanger 1 flows to the first expansion valve 21, and drops to low pressure as it passes through the first expansion valve 21. The low-pressure refrigerant evaporates in the second heat exchanger 2. The refrigerant from the second heat exchanger 2 flows to the accumulator 9 and passes through it, then returns to the inlet 7a of the compressor 7.

[0261] Figure 5 illustrates the circulation of the refrigerant and heat transfer fluid on a thermal conditioning system from Figure 1.

[0262] In this figure, the portions of circuit 10 in which a flow of refrigerant fluid circulates are in thick solid line, while the portions in which the refrigerant fluid does not circulate are in thin dashed lines.

[0263] Similarly, the circulation of the heat transfer fluid in circuit 20 is shown schematically by a thick continuous line.

[0264] The second expansion valve 22 is in the closed position, and the refrigerant flow in the first branch of the bypass B is zero. The third heat exchanger 3 is not traversed by the refrigerant and does not contribute to the evaporation of the refrigerant.

[0265] Only the heat supplied by the heat transfer fluid allows the refrigerant to evaporate.

[0266]

[0132] The heating device 15 is a heating device for the heat transfer fluid.

[0267] The heating device 15 is configured to provide a thermal power P15 to the heat transfer fluid.

[0268]

[0133] The heating device 15 of the heat transfer fluid is here an electric heater.

[0269] The heat transfer fluid heating device 15 includes a heating element, not shown, which dissipates heat when an electric current passes through it. The heat dissipated by the heating element heats the heat transfer fluid. The heating element includes an electrical resistance.

[0270] The heating device 15 can be selectively activated or deactivated, by circulating electric current through the heating element or by interrupting the circulation of electric current.

[0271] The thermal power P15 supplied by the heating device 15 can be controlled by adjusting the intensity of the electric current flowing through the heating element. An electronic control module, not shown, allows for real-time management of the electrical power supplied to the heating element, and therefore the thermal power supplied by the heating device 15. The electronic control module can be integrated into the heating device 15.

[0272]

[0134] According to certain operating modes of the thermal conditioning system 100, the element 25 of the vehicle's electric drive chain can be cooled.

[0273] This scenario may correspond, in particular, to an operation established under conditions of high electrical power supplied, or received.

[0274] In this phase of operation, the heat transfer fluid cooled by the evaporation of the refrigerant in the second exchanger 2 circulates in the element 25 and cools it.

[0275]

[0135] According to other operating modes of the thermal conditioning system 100, the element 25 of the vehicle's electric drive chain can be heated.

[0276] This scenario may correspond to a phase of vehicle activation in a cold ambient temperature, for example below 0°C.

[0277] In this phase of operation, the heat transfer fluid heated by the heating device 15 circulates in the element 25 and heats it.

[0278]

[0136] According to one aspect of the proposed control method, the method comprises:

[0279] - receive a target thermal power C_P1 to be supplied to the indoor airflow Fi in the first exchanger 1,

[0280] and the thermal power P1 supplied to the internal airflow Fi in the first heat exchanger 1 is less than or equal to the target thermal power C_P1 to be supplied to the internal airflow Fi in the first heat exchanger 1.

[0137] The proposed method ensures that the traction chain element 25 receives the expected thermal power, thus heating it at the expected rate. When the thermal power P15 of the heat transfer fluid heating device 15 is insufficient to simultaneously provide enough thermal power for the evaporation of the refrigerant in the second heat exchanger 2 and for heating the traction chain element 25, the thermal power P1 actually supplied to the internal airflow Fi at the first heat exchanger 1 may be less than the setpoint value C_P1. In other words, priority is given to heating the traction chain element 25 over heating the internal airflow Fi.

[0281]

[0138] According to an embodiment of the proposed control method, in which the refrigerant circuit 10 comprises a compressor 7 configured to deliver a flow rate Q_r of high-pressure refrigerant, the compressor 7 having a rotational speed N7,

[0282] The step of controlling the temperature difference D2 of the heat transfer fluid between the inlet 2c and the outlet 2d of the second heat exchanger 2 comprises the following sub-steps:

[0283] - reduce the rotation speed N7 of compressor 7 if the temperature difference D2 of the heat transfer fluid between the inlet 2c and the outlet 2d of the second heat exchanger 2 is greater than a target value C_D2,

[0284] - increase the rotation speed N7 of compressor 7 if the temperature difference D2 of the heat transfer fluid between the inlet 2c and the outlet 2d of the second exchanger 2 is less than the target value C_D2.

[0285]

[0139] Compressor 7 is a centrifugal compressor.

[0286] The flow rate Q_r of refrigerant discharged by the compressor 7 depends on the rotational speed of the compressor 7.

[0287]

[0140] All other parameters remaining constant, the pressure at the inlet 7a of the compressor 7 is a decreasing function of the rotational speed N7 of the compressor 7.

[0288] Thus, by increasing the rotational speed N7 of compressor 7, the pressure at the inlet 7a of compressor 7 decreases. Conversely, by decreasing the rotational speed N7 of compressor 7, the pressure at the inlet 7a of compressor 7 increases. The pressure at the inlet 7a of compressor 7 is approximately the same as the pressure at the outlet of the second heat exchanger 2, as the pressure drop between the outlet 2b of the second heat exchanger 2 and the inlet 7a of compressor 7 is negligible. Consequently, the rotational speed N7 of compressor 7 allows control of the evaporation pressure, and therefore the evaporation temperature, of the refrigerant in the second heat exchanger 2, and thus the temperature difference D2 of the heat transfer fluid between the inlet 2c and the outlet 2d of the second heat exchanger 2.

[0289]

[0141] Compressor 7 is an electric compressor.

[0290] In other words, the compressor 7 includes an electric motor 8 which can rotate the moving parts of the compressor, so as to compress the refrigerant.

[0291] The rotation speed N7 of the compressor 7 can be controlled by the electric current supplying the electric motor 8 of the compressor 7.

[0292] The flow rate Q_r of refrigerant discharged by the compressor 7 can vary in real time.

[0293] An electronic module, not shown, allows real-time control of the electric current supplying the electric motor 8 of the compressor 7.

[0294]

[0142] The heat transfer fluid circuit 20 includes a circulation pump 17 configured to circulate the heat transfer fluid in the circuit 20. The pump 17 is unidirectional here, i.e. its discharge direction cannot be changed.

[0295] The heat transfer fluid flows successively through the heating device 15, then the second heat exchanger 2, and finally the component 25 of the vehicle's electric drive system. In the example shown, the circulation pump 17 is located on the circuit 20 downstream of the second heat exchanger 2 and upstream of the component 25 of the drive system. In other words, the heat transfer fluid from the outlet 2d of the second heat exchanger 2 is drawn in by the circulation pump 17 and then pumped by this pump 17 to the component 25 of the drive system.

[0296] According to variants not shown, the circulation pump 17 can be located at another point in the circuit 20, respecting the order of passage of the heat transfer fluid which has been stated previously.

[0297]

[0143] The circulation pump 17 is an electric pump.

[0298] The flow rate Q_c of heat transfer fluid in circuit 20 can vary in real time. The flow rate Q_c of heat transfer fluid in circuit 20 depends on the rotation speed N17 of the circulation pump 17.

[0299] An electronic module allows real-time control of the electric current supplying the electric motor of the circulation pump 17, which allows adjustment on demand of the flow rate Q_c of heat transfer fluid discharged by the electric pump 17.

[0300]

[0144] According to another aspect of the proposed process, the maximum thermal power P2_max that can be supplied to the refrigerant by the heat transfer fluid, in the second heat exchanger 2, depends on the thermal power P15 supplied by the heating device 15 to the heat transfer fluid.

[0301]

[0145] The value of the maximum thermal power parameter P2_max can thus be adapted in real time to the actual operating conditions.

[0302]

[0146] The thermal power P15 supplied by the heating device 15 can vary between zero power and a maximum power P15_max.

[0303] The thermal power P15 supplied by the heating device 15 can vary in real time.

[0304]

[0147] The maximum thermal power P2_max that can be supplied to the refrigerant by the heat transfer fluid, in the second heat exchanger 2, is equal to the difference between the thermal power P15 supplied by the heating device 15 and the target thermal power C_P25 to be supplied to the element 25 of the traction chain by the heat transfer fluid.

[0305] Thus, element 25 receives the expected target thermal power C_P25. The heating function of element 25 therefore takes priority over the heating function of the internal airflow Fi.

[0306]

[0148] In other words, the value of the maximum thermal power P2_max that can be supplied to the refrigerant by the heat transfer fluid is determined by the formula:

[0307] [Math. 1]

[0308] P2_max = P15 — C_P2S

[0309]

[0149] with:

[0310] P15: Actual thermal power supplied by the heating device 15, inW,

[0311] C_P25: Target thermal power C_P25 to be supplied to element 25 of the traction chain, in W.

[0312]

[0150] According to one embodiment of the proposed method, in which the heating device 15 is configured to provide a maximum thermal output P15_max, the method comprises the step:

[0313] - increment the thermal power P15 supplied by the heating device 15 until the maximum thermal power P15_max is supplied to the heat transfer fluid.

[0314]

[0151] When the heating requirement is high, the power supplied by the heating device 15 is increased, if necessary until the heating device 15 supplies its maximum power.

[0315]

[0152] The maximum thermal power P15_max supplied to the heat transfer fluid is obtained when the heating device 15 consumes its maximum electrical power.

[0316] The maximum power P15_max of the heating device 15 corresponds, for example, to the power supplied when the heating device 15 is continuously controlled with the maximum permissible current.

[0317] The maximum thermal power P15_max of the heating device 15 is for example between 5 kW and 12 kW, depending on the model used.

[0318]

[0153] According to another aspect of the proposed process, the process comprises the steps: - determining a target thermal power C_P1 to be supplied by the refrigerant to the internal airflow Fi at the level of the first exchanger 1,

[0319] - determine a thermal power P7 received by the refrigerant at the compressor 7,

[0320] - determine a target thermal power C_P2 to be supplied to the refrigerant at the level of the second heat exchanger 2, the target thermal power C_P2 being equal to the difference of the target thermal power C_P1 to be supplied by the refrigerant to the internal air flow Fi at the level of the first exchanger 1 and the thermal power P7 received by the refrigerant at the level of the compressor 7, - determine a corrected target thermal power C_P2_cor to be supplied to the refrigerant at the level of the heat exchanger 2, the corrected target thermal power C_P2_cor being equal to the minimum value between the determined target thermal power C_P2 and the maximum thermal power P2_max in the second exchanger 2.

[0321]

[0154] When the corrected target thermal power C_P2_cor differs from the target thermal power C_P2, the thermal power P1 actually supplied to the interior airflow Fi at the first heat exchanger 1 is less than the target thermal power C_P1. The temperature rise of the passenger compartment is slower than required by the setpoint, so as to leave sufficient thermal power to ensure the heating of element 25. Meeting the heating setpoint for element 25 of the powertrain takes priority over meeting the passenger compartment heating setpoint when both setpoints cannot be met simultaneously.

[0322]

[0155] The target thermal power C_P1 to be supplied by the refrigerant to the interior airflow Fi is the thermal power to be supplied to the interior airflow Fi in order to ensure thermal comfort in the vehicle's passenger compartment.

[0323] The target thermal power C_P1 is, for example, determined by an algorithm managing the thermal comfort of the vehicle's passenger compartment, based in particular on the ambient temperature outside the vehicle, the actual temperature inside the passenger compartment, and the setpoint temperature set by the vehicle's occupants.

[0324] This control algorithm will not be detailed here.

[0325]

[0156] The target thermal power C_P2 to be supplied to the refrigerant at the level of the second heat exchanger 2 is the thermal power to be transferred from the heat transfer fluid to the refrigerant, in the second exchanger 2, to close the thermodynamic cycle allowing the target thermal power C_P1 to be supplied at the level of the first exchanger 1.

[0326]

[0157] The corrected target thermal power C_P2_cor is the target thermal power C_P2, possibly limited to the value of the maximum permissible thermal power P2_max at that instant.

[0327] In other words, as long as the target thermal power C_P2 is less than or equal to the maximum permissible thermal power P2_max, the corrected target thermal power C_P2_cor takes the same value as the target thermal power C_P2. If the target thermal power C_P2 is greater than the maximum permissible thermal power P2_max, the corrected target thermal power C_P2_cor takes the value of the maximum permissible thermal power P2_max.

[0328]

[0158] The corrected target thermal power C_P2_cor to be supplied to the refrigerant at the level of the second heat exchanger 2 is thus determined by the formula:

[0329] [Math. 2]

[0330] C_P2_cor = min(C_P2 , P2_max)

[0331]

[0159] with:

[0332] C_P2_cor: Corrected target thermal power, in W,

[0333] C_P2: Target thermal power C_P2 determined, in W

[0334] P2_max: Maximum thermal power P2_max in the second exchanger 2, in W.

[0335]

[0160] The target thermal power C_P1 to be supplied by the refrigerant to the internal airflow Fi at the level of the first exchanger 1 can be determined in different ways.

[0336]

[0161] According to an example of implementation of the proposed process, the value of the target thermal power C_P1 to be supplied by the refrigerant to the internal airflow Fi at the level of the first exchanger 1 is equal to the product:

[0337] - of the indoor airflow rate Fi,

[0338] - of the heat capacity of the indoor airflow Fi, and

[0339] - the difference between the target temperature of the indoor airflow Fi at the outlet of the first exchanger 1 and the temperature of the indoor airflow Fi at the inlet of the first exchanger 1.

[0340]

[0162] The value of the target thermal power C_P1 to be supplied by the refrigerant to the internal airflow Fi at the level of the first heat exchanger 1 is in this case determined by the formula:

[0341] [Math. 3]

[0342] C_P1 = Q_Fi * cpFi * (C.Tlfi - TOFi)

[0343]

[0163] with:

[0344] C_P1: Target thermal power to be supplied at the first exchanger, in W, Q_Fi: Flow rate of the indoor air flow Fi heated by the first exchanger 1, in kg / s, cpFi: Heat capacity of the indoor air flow Fi, in J / kg / K, C_T1 fi: Target temperature of the indoor air flow Fi at the outlet of the first exchanger 1, in °C,

[0345] TOFi: Temperature of the indoor airflow Fi at the inlet of the first exchanger 1, in °C.

[0346]

[0164] Other formulas for modelling the target thermal power C_P1 can of course be used.

[0347]

[0165] According to one embodiment, the thermal conditioning system 100 includes a motor-fan unit, not shown in the figures, configured to provide a flow rate Q_Fi of indoor airflow Fi at the level of the first exchanger 1.

[0348] The flow rate Q_Fi of the indoor air flow Fi heated by the first exchanger 1 is determined from a control voltage of the motor-fan unit.

[0349]

[0166] The control voltage applied to the electric motor of the fan unit determines the rotational speed of the fan unit, and therefore the airflow rate supplied. The fan unit is, for example, located upstream of the first heat exchanger 1.

[0350]

[0167] According to one variant, the flow rate Q_Fi of the interior airflow Fi heated by the first exchanger 1 is determined from a control voltage of the motor-fan unit and from the forward speed of the vehicle.

[0351] In other words, the flow rate Q_Fi of the interior airflow Fi heated by the first heat exchanger 1 can be determined from two independent parameters: the control voltage and the vehicle's forward speed. This two-parameter modeling improves the accuracy of the estimation.

[0352]

[0168] The target temperature C_T1 Fi of the indoor airflow Fi at the outlet of the first exchanger 1 is the desired temperature for the indoor airflow Fi after it has been heated by the first exchanger 1.

[0353] This target temperature is determined by the control algorithm managing the thermal comfort of the passenger compartment.

[0354]

[0169] The TOFi temperature of the indoor airflow Fi upstream of the first exchanger 1 is the actual temperature of the indoor airflow Fi before it has been heated by the first exchanger 1.

[0355] When the first exchanger 1 is located downstream of another heat exchanger through which the indoor air flow Fi passes, this temperature is substantially equal to the temperature of the indoor air flow Fi downstream of this other heat exchanger.

[0356]

[0170] The temperature TOFi of the indoor airflow Fi upstream of the first heat exchanger 1 is, for example, measured by a measuring sensor disposed in the airflow Fi, upstream of the first heat exchanger 1 in the direction of flow of the airflow Fi. The measuring sensor can be, for example, a thermistor or a thermocouple.

[0357]

[0171] The thermal power P7 received by the refrigerant at the compressor 7 is for example determined from the electrical power PE7 absorbed by the compressor and from a correction coefficient K.

[0358] For example, the thermal power P7 received by the refrigerant at the compressor 7 is equal to the electrical power PE7 absorbed by the compressor 7 multiplied by a correction coefficient K.

[0359]

[0172] The thermal power P7 received by the refrigerant at the compressor 7 is thus determined by the formula:

[0360]

[0173] [Math. 4]

[0361] P7 = PE7 * K

[0362]

[0174] with:

[0363] P7: Thermal power received by the refrigerant at the compressor, in W.

[0364] PE7: Electrical power consumed by the compressor, in W

[0365] K: Dimensionless correction coefficient.

[0366]

[0175] The correction coefficient K corresponds to the inverse of the isentropic efficiency of the compressor 7.

[0367] This correction coefficient can be determined from different models. The determined value of the correction coefficient can be updated in real time.

[0368]

[0176] According to one embodiment, the correction coefficient K is determined as a function of the rotational regime N of the compressor 7.

[0369] The correction coefficient K is for example determined by a one-dimensional mapping, i.e. a table of values ​​with a single input.

[0177] The correction coefficient K can also be determined as a function of the rotational speed N of the compressor 7 and as a function of the flow rate discharged by the compressor 7.

[0370] The correction coefficient K is, for example, determined by a two-dimensional mapping, that is, a table of values ​​with two inputs.

[0371]

[0178] According to an example of implementation of the proposed process, the process comprises the following steps:

[0372] - determine a temperature of the heat transfer fluid Tc2Jn at the inlet of the second heat exchanger 2,

[0373] - determine a heat transfer fluid flow rate Q_c in the second heat exchanger 2, - determine a target temperature of the heat transfer fluid C_Tc2_out at the outlet of the second heat exchanger 2 from the temperature of the heat transfer fluid Tc2Jn at the inlet of the second heat exchanger 2, the corrected target thermal power C_P2_cor to be supplied to the refrigerant at the level of the second heat exchanger 2, and the heat transfer fluid flow rate Q_c in the second heat exchanger 2, - reduce the compressor speed 7 if the temperature of the heat transfer fluid Tc2_out at the outlet of the second heat exchanger 2 is lower than the target temperature of the heat transfer fluid C_Tc2_out at the outlet of the second heat exchanger 2,

[0374] - increase the rotation speed of compressor 7 if the temperature of the heat transfer fluid Tc2_out at the outlet of the second exchanger 2 is higher than the target temperature of the heat transfer fluid C_Tc2_out at the outlet of the second exchanger 2.

[0375]

[0179] The temperature Tc2_out of the heat transfer fluid at the outlet 2d of the second exchanger 2 is used as the input parameter of the regulation, which allows simple and precise control.

[0376]

[0180] The process includes the substep:

[0377] - determine a specific heat capacity cpc of the heat transfer fluid in the second exchanger 2.

[0378]

[0181] According to one aspect of the proposed process, the target temperature of the heat transfer fluid C_Tc2_out at the outlet of the second heat exchanger 2 is equal to the difference between: - the temperature of the heat transfer fluid Tc2Jn at the inlet of the second heat exchanger 2, and

[0379] - the quotient of:

[0380] -- the corrected target thermal power C_P2_cor to be supplied to the refrigerant at the level of the second heat exchanger 2, and the

[0381] -- product of the flow rate of heat transfer fluid Q_c in the second exchanger 2 and the heat capacity cpc of the heat transfer fluid in the second exchanger 2.

[0382]

[0182] The use of a physical model of heat exchange in the second exchanger 2 allows for rapid and precise regulation.

[0383]

[0183] The target temperature of the heat transfer fluid C_Tc2_out at the outlet of the second heat exchanger 2 is thus determined by the formula:

[0384] [Math. 5]

[0385]

[0386]

[0184] with:

[0387] C_Tc2_out: Target temperature of the heat transfer fluid C_Tc2_out at outlet 2b of the second heat exchanger 2, in °C,

[0388] Tc2Jn: Temperature of the heat transfer fluid Tc2Jn at the inlet 2a of the second heat exchanger 2, in °C,

[0389] C_P2_cor: Corrected target thermal power C_P2_cor to be supplied to the refrigerant at the level of the second heat exchanger 2, in W,

[0390] Q_c: Flow rate of heat transfer fluid Q_c in the second exchanger 2, in kg / s, cpc: Heat capacity cpc of the heat transfer fluid in the second exchanger, in J / kg / K.

[0391]

[0185] The flow rate of heat transfer fluid Q_c in the second exchanger 2 is determined for example from a model based on the rotation speed N17 of the circulation pump 17 of the heat transfer fluid circuit 20.

[0392] The rotation speed of the circulation pump 17 of the heat transfer fluid circuit 20 is, for example, determined by a rotation speed sensor of a shaft of the circulation pump 17.

[0393]

[0186] According to one embodiment, the proposed process comprises:

[0394] - determine a subcooling Sr of the refrigerant fluid at the outlet of the first heat exchanger 1,

[0395] - determine a target value C_Sr for the subcooling of the refrigerant at the outlet of the first heat exchanger 1,

[0396] - control an effective passage section of the first expansion valve 21 so that the subcooling Sr of the refrigerant at the outlet of the first exchanger 1 is equal to the target value C_Sr of the subcooling of the refrigerant at the outlet of the first exchanger 1.

[0397]

[0187] The expansion rate achieved by the first expansion valve 21 allows the thermodynamic cycle to be optimized by adjusting the subcooling to a value that maximizes the thermodynamic efficiency.

[0398]

[0188] By definition, the subcooling Sr of the refrigerant fluid at the outlet of the first exchanger 1 is equal to the difference between the temperature of the refrigerant fluid and the saturation temperature for a pressure corresponding to its actual pressure.

[0399]

[0189] The process thus includes a substep of determining the pressure of the refrigerant fluid at the outlet of the first exchanger 1, a substep of determining the saturation temperature of the refrigerant fluid for the determined pressure.

[0400]

[0190] The process comprises:

[0401] - if the subcooling of the refrigerant at the outlet of the first exchanger 1 is less than the target value, decrease the effective passage area of ​​the first expansion valve 21.

[0402]

[0191] The process comprises:

[0403] - if the subcooling of the refrigerant at the outlet of the first exchanger 1 is greater than the target value, increase the effective passage area of ​​the first expansion valve 21.

[0404]

[0192] The proposed method can be coded in the form of a program executable by an electronic control unit.

[0405] Thus, the invention also relates to a computer program stored in memory, and configured to implement the process described above.

Claims

39 Demands

1. A method for controlling a thermal conditioning system (100) for a motor vehicle, the thermal conditioning system (100) comprising: - a refrigerant circuit (10) configured to circulate a refrigerant, the refrigerant circuit (10) comprising a first heat exchanger (1) configured to supply thermal power (P1) to an internal airflow (Fi), - a heat transfer fluid circuit (20) configured to circulate a heat transfer fluid, the heat transfer fluid circuit (20) comprising successively, according to a direction of heat transfer fluid circulation: -- a heating device (15) for the heat transfer fluid, -- a second heat exchanger (2) jointly disposed on the refrigerant circuit (10) and on the heat transfer fluid circuit (20), the second heat exchanger (2) being configured to allow heat exchange between the refrigerant and the heat transfer fluid, the second heat exchanger (2) having a heat transfer fluid inlet (2c) and a heat transfer fluid outlet (2d), the second exchanger (2) being configured to evaporate at least part of the refrigerant from the first exchanger (1), -- an element (25) of an electric powertrain of the vehicle, the process comprising: (1) activate the heating device (15) so as to supply thermal power (P15) to the heat transfer fluid, (ii) receive a target thermal power (C_P25) to be supplied to the element (25) of the traction chain by the heat transfer fluid, (iii) receive a maximum thermal power (P2_max) that can be supplied to the refrigerant by the heat transfer fluid, in the second heat exchanger (2), (iv) circulating heat transfer fluid in the heat transfer fluid circuit (20) so as to supply thermal power (P2) to the refrigerant in the second heat exchanger (2) and to supply thermal power (P25) to the traction chain element (25),40 and including: (v) control a temperature difference (D2) of the heat transfer fluid between the inlet (2c) and the outlet (2d) of the second heat exchanger (2) such that: - the thermal power (P25) supplied to the element (25) of the traction chain by the heat transfer fluid is equal to the target thermal power (C_P25), and - the thermal power (P2) supplied to the refrigerant in the second heat exchanger (2) is less than or equal to the maximum thermal power (P2_max) that can be supplied in the second heat exchanger (2).

2. A control method according to claim 1, comprising: - receiving a target thermal power (C_P1) to be supplied to the indoor airflow (Fi) in the first exchanger (1), in which the thermal power (P1) supplied to the indoor airflow (Fi) in the first exchanger (1) is less than or equal to the target thermal power (C_P1) to be supplied to the indoor airflow (Fi) in the first exchanger (1).

3. A control method according to claim 1 or 2, wherein the refrigerant circuit (10) comprises a compressor (7) configured to deliver a flow rate (Q_r) of refrigerant at high pressure, the compressor (7) having a rotational speed (N7), process in which the step of controlling the temperature difference (D2) of the heat transfer fluid between the inlet (2c) and the outlet (2d) of the second heat exchanger (2) comprises the substeps: - reduce the rotation speed (N7) of the compressor (7) if the temperature difference (D2) of the heat transfer fluid between the inlet (2c) and the outlet (2d) of the second heat exchanger (2) is greater than a target value (C_D2), - increase the rotation speed (N7) of the compressor (7) if the temperature difference (D2) of the heat transfer fluid between the inlet (2c) and the outlet (2d) of the second exchanger (2) is less than the target value (C_D2).

4. A method according to any one of the preceding claims in combination with claim 3, wherein the maximum thermal power (P2_max) that can be supplied to the refrigerant by the heat transfer fluid in the second heat exchanger (2) depends on the thermal power (P15) supplied by the heating device (15) to the heat transfer fluid.41

5. A method according to the preceding claim, wherein the maximum thermal power (P2_max) that can be supplied to the refrigerant by the heat transfer fluid, in the second heat exchanger (2), is equal to the difference between the thermal power (P15) supplied by the heating device (15) and the target thermal power (C_P25) to be supplied to the element (25) of the traction chain by the heat transfer fluid.

6. A method according to any one of the preceding claims, wherein the heating device (15) is configured to provide maximum thermal power (P15_max), and wherein the method comprises the step: - incrementing the thermal power (P15) supplied by the heating device (15) until it provides the maximum thermal power (P15_max) to the heat transfer fluid.

7. A method according to any one of the preceding claims, comprising the steps: - determine a target thermal power (C_P1) to be supplied by the refrigerant to the internal airflow (Fi) at the level of the first exchanger (1), - determine a thermal power (P7) received by the refrigerant at the compressor (7), - determine a target thermal power (C_P2) to be supplied to the refrigerant at the level of the second heat exchanger (2), the target thermal power (C_P2) being equal to the difference of the target thermal power (C_P1) to be supplied by the refrigerant to the internal airflow (Fi) at the level of the first exchanger (1) and the thermal power (P7) received by the refrigerant at the level of the compressor (7), - determine a corrected target thermal power (C_P2_cor) to be supplied to the refrigerant at the level of the heat exchanger (2), the corrected target thermal power (C_P2_cor) being equal to the minimum value between the determined target thermal power (C_P2) and the maximum thermal power (P2_max) in the second exchanger (2).

8. A method according to the preceding claim, wherein the value (C_P1) of the target thermal power (C_P1) to be supplied by the refrigerant to the indoor airflow (Fi) at the level of the first exchanger (1) is equal to the product of the flow rate (Q_Fi) of the indoor airflow (Fi), the heat capacity (cpFi) of the indoor airflow (Fi), and the difference between a target temperature (C_T1fi) of the indoor airflow (Fi) at the outlet of the first exchanger (1) and the temperature (TOFi) of the indoor airflow (Fi) at the inlet of the first exchanger (1).

9. A method according to claim 7 or 8, comprising the steps: - determining a temperature of the heat transfer fluid (Tc2Jn) at the inlet of the second exchanger (2), - determine a heat transfer fluid flow rate (Q_c) in the second heat exchanger (2), - determine a target temperature of the heat transfer fluid (C_Tc2_out) at the outlet of the second heat exchanger (2) from the temperature of the heat transfer fluid (Tc2Jn) at the inlet of the second heat exchanger (2), the corrected target thermal power (C_P2_cor) to be supplied to the refrigerant at the level of the second heat exchanger (2), and the heat transfer fluid flow rate (Q_c) in the second heat exchanger (2), - reduce the compressor rotation speed (7) if the temperature of the heat transfer fluid (Tc2_out) at the outlet of the second heat exchanger (2) is lower than the target temperature of the heat transfer fluid (C_Tc2_out) at the outlet of the second heat exchanger (2), - increase the compressor rotation speed (7) if the temperature of the heat transfer fluid (Tc2_out) at the outlet of the second exchanger (2) is higher than the target temperature of the heat transfer fluid (C_Tc2_out) at the outlet of the second exchanger (2).

10. A method according to the preceding claim, wherein the target temperature of the heat transfer fluid (C_Tc2_out) at the outlet of the second heat exchanger (2) is equal to the difference between: - the temperature of the heat transfer fluid (Tc2Jn) at the inlet of the second heat exchanger (2), and - the quotient of: -- the corrected target thermal power (C_P2_cor) to be supplied to the refrigerant at the level of the second heat exchanger (2), and the -- product of the flow rate of heat transfer fluid (Q_c) in the second exchanger (2) and of the heat capacity (cpc) of the heat transfer fluid in the second exchanger (2).

11. A method according to any one of the preceding claims, comprising: - determine a subcooling (Sr) of the refrigerant at the outlet of the first heat exchanger (1), - determine a target value for the subcooling of the refrigerant at the outlet of the first heat exchanger (1), - control an effective passage area of ​​a first expansion valve (21) so that the subcooling of the refrigerant at the outlet of the first exchanger (1) is equal to the target value of the subcooling of the refrigerant at the outlet of the first exchanger (1).

12. Thermal conditioning system (100) comprising: - a heat transfer fluid circuit (20) configured to circulate a heat transfer fluid, - a refrigerant circuit (10) configured to circulate a refrigerant, comprising a main refrigerant circulation loop (A) comprising successively, according to a direction of refrigerant circulation: - a compressor (7), - a first heat exchanger (1) thermally coupled with an interior airflow (Fi) to a vehicle passenger compartment, - a first regulator (21), - a second heat exchanger (2), jointly arranged on the refrigerant circuit (10) and on the heat transfer fluid circuit (20), the second heat exchanger (2) being configured to allow heat exchange between the refrigerant and the heat transfer fluid, in which the heat transfer fluid circuit (20) comprises successively, according to a direction of flow of the heat transfer fluid: a heating device (15) for the heat transfer fluid, the second heat exchanger (2), an element (25) of an electric drive chain for the vehicle, - an electronic control unit (60) configured to implement the method according to one of the preceding claims.44

13. Thermal conditioning system (100) according to the preceding claim, comprising: - a first bypass branch (B) arranged in parallel with the first expansion valve (21) and the second heat exchanger (2), the first bypass branch (B) comprising successively: -- a second regulator (22), -- a third heat exchanger (3) thermally coupled with an outside airflow (Fe), - a second bypass branch (C) arranged in parallel with the first expansion valve (21) and the second heat exchanger (2), the second bypass branch (C) comprising successively: -- a third regulator (23), -- a fourth heat exchanger (4) thermally coupled with the indoor airflow (Fi).

14. Computer program stored on a computer-readable medium and comprising code instructions configured to implement the method according to any one of claims 1 to 11.

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