TEMPERATURE CONTROL STRATEGY FOR AN ELECTRIC STARTER SYSTEM WITH A MULTI-PHASE, BRUSHLESS STARTER MOTOR

Abstract

Electric starter system (12) for use with an internal combustion engine (20) having a flywheel (32), wherein the electric starter system (12) comprises the following: a brushless starter (18) with a machine temperature; a pinion gear (33); an electromagnet (21) which can be operated to translate the pinion into engagement with the flywheel (32) in order to connect the brushless starter (18) with the flywheel (32) in response to a requested engine start event; and a controller (50) programmed with a temperature control logic (150L) that has a proportional-integral (PI) torque control loop; wherein the execution of the temperature control logic (150L) by the controller (50) in response to the requested motor start event, when the machine temperature is greater than a first temperature, causes the controller (50) to determine a required starting torque of the brushless starter (18) via the PI torque control loop at a level that reduces the machine temperature below the first temperature, to control the electromagnet (21), to shift the pinion gear (33) into engagement with the flywheel (32), and to control the delivery of the required starting torque by the brushless starter (18) to the internal combustion engine (20).

Description

INTRODUCTION

[0001] Powertrains, power plants, and other systems may include an internal combustion engine that generates engine torque in response to an acceleration request. The generated engine torque is transmitted to a coupled consumer via a power transmission arrangement, such as a planetary gear assembly or one or more planetary gear sets. In some powertrain configurations, an electric machine called a starter may be used to assist in a starting function of the engine, for example, in the automatic restart of the engine after a fuel-saving engine auto-stop event. A rotor of the starter may be connected to an engine crankshaft, for example, by a meshing gear with a flywheel. The engine torque of the starter is then used to accelerate the engine to an initial speed.The starter is then disconnected from the engine once the engine has started and is able to maintain a threshold for the idle speed.

[0002] US 2010 / 0154524A1 describes a method for determining the starting capability of a starting system for an internal combustion engine. For the starting system, the average power output of a battery is determined during an engine starting interval. The temperature of the starting system is determined at the beginning of the engine starting interval. A predetermined average power output for a fully charged battery at the determined temperature is looked up. A predetermined minimum average power output is determined that the battery must provide to start the respective engine at the determined temperature. Based on the determined average power outputs, a functional state is established. The starting capability of the starting system is identified as a response to the established functional state. SUMMARY

[0003] This document discloses an electric starter system. The electric starter system, configured for use with a powertrain or other system with an internal combustion engine, includes an electromagnet, a geared pinion, and a multi-phase brushless starter with a rotor and a ring gear. The brushless starter can be selectively connected to the engine's flywheel by actuating the electromagnet in response to a desired engine start event. The gear reduction of the pinion, driven by the electromagnet, engages the pinion with the ring gear and the flywheel. In this way, the engine torque of the starter is transmitted to the flywheel via the rotation of the interposed pinion.

[0004] The electric starter system also includes an electronic control unit. One or more temperature sensors can optionally be connected to the brushless starter, for example, to a pair of phase windings and / or a lamination slot or other physical structure of the brushless starter. The temperature sensors output electronic signals indicating the temperature level of the brushless starter, which is referred to here as the machine temperature. Alternatively, a state monitor located within the control unit or in a separate control device can be used to estimate the machine temperature in real time.

[0005] The controller is configured to regulate the starter temperature by automatically limiting the starter output power, and therefore the motor torque, based on the machine temperature. For this purpose, the controller is programmed with proportional-integral (PI) control logic, forming a torque control loop. Heat in the starter tends to increase when the starter operates at a combination of low speed and high torque. This low-speed / high-torque operating mode is typically present during an automatic engine restart. Therefore, the controller uses a temperature-dependent method to regulate the machine temperature during such low-speed / high-torque operation.

[0006] The execution of the temperature control logic in response to the requested motor start event ultimately causes the controller to determine the required starting torque of the starter motor and transmit a torque command to the starter motor so that the starter motor transmits the required starting torque to the motor. The required starting torque has a value that, by activating the programmed logic, automatically limits the output power of the starter motor depending on the machine temperature, thus keeping the machine temperature within a permissible range.

[0007] Within the disclosed PI control loop, the integral gain is influenced by the machine temperature, and therefore the integral gain in the control loop is automatically changed when the machine temperature changes. In various embodiments, the integral gain can be a first-order function of the machine temperature or determined by accessing a lookup table that is populated or referenced by the machine temperature. The rotor flux within the starter is also closely related to the machine temperature and is therefore also considered a control parameter within the control loop. As with the integral gain, the rotor flux can be determined mathematically or via a lookup table. Since the terminal voltage of the starter changes with the machine temperature, this value can also be used by the controller in the overall control of the starter.

[0008] In one possible embodiment, an electric starting system includes a brushless starter operating at machine temperature, an electromagnet capable of converting a pinion gear into engagement with a flywheel of a motor, thereby connecting the brushless starter to the flywheel in response to a desired motor starting event, and a controller. The controller is programmed with temperature control logic and a PI torque control loop.

[0009] The execution of the temperature control logic by the controller in response to the requested motor start event, when the machine temperature is higher than a first temperature, causes the controller, via the PI torque control loop, to determine the required starting torque of the brushless starter at a level that reduces the machine temperature below the first temperature. The controller also controls the solenoid valve to move the pinion gear into engagement with the flywheel and deliver the required starting torque to the motor via the brushless starter.

[0010] The controller can cancel the requested motor start event via the PI torque control loop if the machine temperature is greater than a second temperature that exceeds the first temperature.

[0011] The brushless starter can be electrically connected to an inverter module (PIM). In such an embodiment, the controller can be configured to generate or control pulse width modulation of the PIM to provide the required starting torque at the level that reduces the machine temperature below the initial temperature.

[0012] The electric starter system can include at least one temperature sensor positioned on or inside the brushless starter motor and configured to measure the machine temperature. Alternatively, the controller can include a state monitor suitable for estimating the machine temperature in real time.

[0013] The controller can use a q-axis current command, a d-axis current command, a q-axis feedback current and a d-axis feedback current as inputs via the PI torque control loop, apply an integral gain that is indexed or referenced by the machine temperature, and generate a q-axis voltage command and a d-axis voltage command to the starter as outputs.

[0014] The PI torque control loop can also include a flux chaining block that calculates a back EMF of the brushless starter as the product of an angular velocity and a flux leakage value of the starter, where the flux leakage value is referenced to the machine temperature. In such an embodiment, the controller is configured to calculate the voltage command of the q-axis using the back EMF.

[0015] A powertrain is also disclosed herein. One embodiment of the powertrain includes an internal combustion engine with a flywheel, a transmission coupled to the engine, a consumer coupled to the transmission, and the electric starter system.

[0016] A method for controlling the temperature of an electric starter system with a brushless starter is also disclosed. The method can include sensing a requested engine start event of an internal combustion engine via a controller, wherein an electromagnet translates a pinion gear into engagement with the brushless starter and the engine. The method can also include determining the machine temperature of the brushless starter using the controller. In response to the requested engine start event, if the machine temperature is higher than the first temperature, the method can further include determining a required starting torque of the starter using a PI torque control loop of the controller. The required starting torque is a value that limits the output power level of the starter to a level sufficient to reduce the machine temperature below a first temperature.The control unit then transmits a torque command to the starter motor to cause the starter motor to transfer the required starting torque to the flywheel of the engine via the pinion gear.

[0017] The summary described above is not intended to represent every embodiment or aspect of the present disclosure. Rather, the foregoing summary merely illustrates some of the novel aspects and features as set forth herein. The features and advantages listed above, as well as other features and advantages of the present disclosure, will be readily apparent from the following detailed description of the embodiments and methods of carrying out the present disclosure, in conjunction with the accompanying drawings and the attached claims. BRIEF DESCRIPTION OF THE DRAWINGS Fig. Figure 1 is a schematic representation of an exemplary drive train with a multiphase brushless starter, the machine temperature of which is used in a proportional-integral (PI) torque control / feedback circuit during a motor-car start event, as set out herein. Fig. 2 is a diagram of the electrical current and speed power values ​​of the in Fig. 1 starter motor shown, where the electric current and rotational speed are shown on the vertical axis and the time on the horizontal axis. Fig. Figure 3 is a schematic logic flowchart that describes an exemplary implementation of the temperature control logic used with the electric starter system of Fig. 1 is usable. Fig. 4 is a flowchart showing an exemplary embodiment of a method for controlling the machine temperature of the in Fig. The starter shown in section 1 describes, in particular during an engine start event.

[0018] For the present disclosure, modifications and alternative forms may be considered, with representative embodiments illustrated by way of example in the drawings and described in detail below. Inventive aspects of this disclosure are not limited to the specific forms of this disclosure. Rather, the present disclosure aims to cover modifications, equivalents, combinations, and alternatives that fall within the scope of protection of the disclosure as defined by the accompanying claims. DETAILED DESCRIPTION

[0019] Embodiments of the present disclosure are described herein. The various embodiments are examples of the present disclosure, while other embodiments in alternative forms are conceivable to those skilled in the field with regard to the disclosure. The figures are not necessarily to scale. Some features may be exaggerated or minimized to illustrate details of the specific components. Therefore, the specific structural and functional details disclosed herein are not to be understood as limiting, but rather as a representative basis for conveying to a person skilled in the art the various possible applications of the present disclosure.As experts also understand, features illustrated and described with reference to a given figure can be combined with features shown in one or more other figures to create embodiments not explicitly shown or described. The illustrated combinations of features thus serve as representative embodiments for typical applications. However, different combinations and modifications of the features, consistent with the teachings of this disclosure, might be desirable for certain applications and implementations.

[0020] Referring to the drawings, in which the same reference numerals refer to the same or similar components in the various figures, a drive train 10 is shown in Fig. Figure 1 is shown schematically. The drive train 10 includes an electric starter system 12, which can be selectively connected to an internal combustion engine (E) 20. The electric starter system 12 includes and / or is controlled by a controller (C) 50. The controller 50 is configured to implement a temperature control method 100 in the overall control of a torque operation of a multiphase / alternating current (AC) brushless electric machine, hereinafter referred to as the brushless starter (M). BL ) 18, to be executed. Thus, the torque feedback control of the starter 18 is automatically carried out by the controller 50 in order to regulate the temperature of the brushless starter 18 as described below.

[0021] The brushless starter 18 can be configured without restriction as a surface permanent magnet machine, an internal permanent magnet machine, a trailing induction machine, a switched reluctance machine, or any other type of brushless motor. As acknowledged herein, brushless motors such as the starter 18 can exhibit a longer service life with improved speed control accuracy compared to certain brushed motors, among other potential advantages.

[0022] The engine 20, which can be a gasoline or diesel engine, ultimately transmits the engine torque to an output shaft 24. The output shaft 24 can be coupled to a transmission (T) 22, for example via a hydrodynamic torque converter or a clutch (not shown). The transmission 22 can be configured as one or more planetary gear sets, a gearbox, or a continuously variable arrangement, which ultimately transmits the output torque to a transmission output element 25 in a suitable gear ratio or transmission ratio. The output element 25, in turn, drives a coupled consumer via one or more drive shafts 28, with the in Fig. The consumer shown in Figure 1 is represented as a set of drive wheels 26 in an exemplary automotive application. Other useful applications for the powertrain 10 can be envisaged, including power plants, robotics, mobile platforms, and non-motor vehicle applications such as watercraft, naval vessels, rail vehicles, and aircraft. Therefore, the embodiment of the motor vehicle in Figure 1 is shown as a set of drive wheels 26 in an exemplary automotive application. Fig. 1 is intended to illustrate the disclosed concepts without restriction.

[0023] The engine 20 of Fig. 1 also includes a crankshaft 31, which is mechanically coupled to a flywheel 32. When the engine 20 is not running, such as after a fuel-saving auto-stop event of the engine 20 or when the engine 20 is switched off, the electric starter system 12 can be activated in response to starter control signals (arrow CC). S) are electrically activated by control unit 50 to selectively control the delivery of motor torque (arrow T) M ) to control the motor 20 via the flywheel 32.

[0024] For this purpose, an electromagnet (S) 21 can be incorporated as part of the electric starter system 12. According to an exemplary embodiment, the electromagnet 21 is arranged between a rotor 19 of the brushless starter 18 and a shaft extension 190, possibly with a gear reduction set (not shown) between the rotor 19 and the electromagnet 21. Alternatively, a fixed ring gear (not shown) can be coupled to the rotor 19, with the electromagnet 21 engaging and disengaging a pinion gear 33 with the flywheel 32 and such a ring gear. A position sensor 36, e.g., a Hall effect sensor, a multiplying encoder, an inductive sensor, or a reluctance sensor, can be used to measure and output an angular position (arrow P). 19 ) of the rotor 19, with which the controller 50 can determine an angular position and speed of the rotor 19.

[0025] In one possible embodiment, when the electromagnet 21 reacts to the starter control signals (arrow CC) S When energized, the electromagnet 21 linearly shifts the pinion gear 33 to the position specified at 33A, thus engaging it directly with opposing teeth or gears on the flywheel 32 and / or an associated transmission element. After the engine 20 has been started and is running at a speed sufficient to maintain its fuel consumption and the combustion process, the starter control signals (arrow CC) are S ) interrupted. As a result of this action, the electromagnet 21 is de-energized. The pinion gear 33 is then disengaged from the flywheel 32 by a return of the electromagnet 21. This bidirectional transmission capability of the pinion gear 33 is Fig. 1 represented by a double arrow SS.

[0026] The exemplary electric starter system 12 of Fig. 1 can include or be connected to a direct current (DC) battery pack 14, e.g., a multi-cell lithium-ion, nickel-metal hydride, or lead-acid battery pack with positive (+) and negative (-) terminals. The electric starter system 12 can include an inverter module (PIM) 16, which is electrically connected via the DC voltage bus 15 through the positive (+) and negative (-) terminals of the battery pack 14, e.g., a 12-48 VDC bus in one possible embodiment, as well as a multi-phase / alternating current (AC) voltage bus 17. Although for the sake of illustrative simplicity, Fig. Except for 1, the PIM 16 includes semiconductor switching pairs, e.g. MOSFETs, which are connected to positive (+) and negative (-) poles via the DC voltage bus 15, and signal filter circuit components which ultimately convert direct current from the battery pack 14 into multiphase current on the AC voltage bus 17.

[0027] The AC bus 17 is electrically connected to individual phase windings within the brushless starter 18. The phase current sensors 13 can be positioned on two or more phase windings or leads of the brushless starter motor 18, as shown, with measured phase currents (arrow I) PH ) are transmitted to the control unit 50. The starter 18 can be configured to provide a calibrated counter-electromotive force for a given power range, e.g., 3–5 V at 6000 rpm, or other values ​​that ensure sufficient motor torque (arrow T). M ) is available to start the motor 20, e.g. 5-7 Nm within the parameters of the DC voltage bus 15.

[0028] According to the present disclosure, the control unit is 50 of Fig. 1 is configured to control the machine temperature of the brushless starter 18 within a permissible temperature range during and after an automatic start event of the motor 20. For this purpose, at least one temperature sensor 11 can be positioned and configured inside the starter 18 to provide a temperature signal (arrow T). 18) to measure and transmit the machine temperature. The temperature sensor 11, for example a thermocouple or a thermistor, can be positioned at an end turn of a specific phase winding (not shown) of the starter 18. Another temperature sensor 11 can be positioned in a lamination slot (not shown) of the starter 18. Alternatively, the temperature sensors 11 can be omitted in favor of a real-time temperature estimate, e.g., via a state monitor of the controller 50. However, the machine temperature is ultimately determined, with the machine temperature being part of a set of input signals (arrow CC). I ) is used on control unit 50.

[0029] The control unit 50 can be implemented variably as one or more control devices that together control the motor torque (arrow T). M) of the brushless starter 18 within the exemplary electric starter system 12, wherein the controller 50 performs this task using the temperature control logic 150L according to a method 100, for which an example is given in Fig. 3 is shown as 150L. Several control modules can be connected via a serial bus (e.g., a CAN (Controller Area Network)) or via separate conductors. The controller 50 can include one or more digital computers, each comprising a processor (P), e.g., a microprocessor or a central processing unit, as well as memory (M) in the form of read-only memory, random access memory, electrically programmable read-only memory, etc., a high-speed clock, an analog-to-digital and digital-to-analog circuit, an input / output circuit and devices, and suitable signal conditioning and buffering circuitry.The controller 50 can also store algorithms and / or computer-executable instructions in memory (M), including the underlying algorithms or code embodying the method 100 described below, and transmit commands to the electric starter system 12 to enable the performance of certain control actions in accordance with the present disclosure.

[0030] The control unit 50 is connected to the motor 20 and also receives input signals (arrow CC). I) Signals indicating the speed and temperature of motor 20, as well as other possible motor operating conditions or parameters. These parameters include a start request for motor 20, regardless of whether it is initiated by the operator or generated autonomously. The controller 50 is also connected to the brushless starter 18 and thus receives signals indicating the current speed, current draw, torque, temperature, and / or other operating parameters. The controller 50 can also be connected to the battery pack 14 and receive signals indicating the battery's state of charge, temperature, current draw, and voltage via the respective DC and AC buses 15 and 17. In addition to transmitting a torque request to the starter 18 via the starter control signals (arrow CC). S ) the controller 50 also transmits output signals (arrow CC) O ) to the motor 20 and the gearbox 22 and engine control signals (arrow CC)M ) to the starter 18 as part of the overall operating function of the control unit 50.

[0031] With reference to Fig. 2 A representative time diagram 40 for the rotational speed N will be shown. 18 of the brushless starter 18, i.e. curve 42, and for the machine current I DC , i.e., curve 44 is shown. The rotational speed in rpm and the current in amperes (A) are shown on the vertical axis, the time in seconds, i.e., t(s), is shown on the horizontal axis. The brushless starter 18 of Fig. 1 is located near the motor 20, so the temperature around the brushless starter 18 is subject to considerable fluctuations under normal operating conditions. Depending on the severity, this temperature fluctuation can, without the current method 100, lead to inconsistent performance of the brushless starter 18 and / or difficulty in starting the motor 20.

[0032] Furthermore, heat generation tends to occur early in a start sequence when the brushless starter 18 operates at low speeds and high torque, e.g., 0-7000 rpm. That is, from t0 to t1 in Fig. At t1, the starter 18 rotates at zero speed, so no current flows through it and no heat is generated. Starting of the motor 20 begins at t1 with a rapid increase in current input to the phase windings of the brushless starter 18. Fig. 1, as shown by the rapidly rising trajectory of curve 42 and the peak current of curve 44, generating a large amount of heat. Starting the engine 20 of Fig. The process repeats between t1 and t2 until the engine 20 starts. The starter 18 is then engaged at speed N at t2. 18 switched off. (Track 42), which then expires when the starter 18 is switched off and the electromagnet 21 engages the pinion gear 33. Fig. 1 departs.

[0033] The control unit 50 is programmed to counteract undesirable temperature influences due to the increasing machine temperature within or around the brushless starter 18. Fig. 1 to be taken into account and compensated for. The phase windings of the starter 18 are typically made of copper, which is an element with a temperature coefficient of 0.393 percent (%) per degree Celsius (°C). Thus, the internal resistance of the conductive parts of the starter 18 varies by 0.393% for every 1°C change in machine temperature. Since the machine temperature during normal operation of the electric starter system 12 Fig. Since the temperature can fluctuate slightly between -40 °C and 180 °C, the controller 50 uses the temperature in the sensor. Fig. 3 described logic 150L to compensate for these temperature changes in real time.

[0034] As in Fig. 3. The temperature control logic 150L can, as different inputs, a predefined quadrature axis / Q-axis current (I). q ) and a direct axis / D-axis stream (I d ) exhibit, which is necessary to achieve a required torque and speed of the brushless starter 18, feedback currents (I q,FB ) and (I d,FB ), as well as integrator scales (V q,SC ) and (V d,SC ) is required. As is known in the technology of electric synchronous machines, the d-axis coincides with an axis of the rotor 19 in a rotating dq reference frame. The q-axis runs perpendicular to the d-axis. The controller 50 is thus configured to transmit a d-axis and q-axis current command to the starter 18 in order to control torque operation of the starter 18.

[0035] The feedback currents (I q,FB ) and (I d,FB) can be calculated in real time by the controller 50. For example, two phase currents, as with phases A and B, are calculated via the in Fig. The currents are measured by the current sensors 13 shown in Figure 1 and transmitted to the controller 50. The controller 50 then converts the measured phase currents into the corresponding feedback current (I). q,FB ) or (I d,FB ) for example, the controller 50 can perform a stationary-to-synchronous frame transformation, i.e., a Cartesian “ABC” frame to a “dq” frame transformation of the rotating machine.

[0036] The integrator scales (V q,SC ) and (V d,SC ) are values ​​that are also used by control unit 50. Fig. 1 can be calculated. For example, if a maximum d-axis control voltage is a predicted value or a preset value between 0.9 and 0.97 of a peak phase voltage, the maximum q-axis control voltage can be calculated from the controller 50, i.e.: Vq=VS2−Vd2 where V q The maximum q-axis control voltage is V d the maximum d-axis control voltage is and V S The peak phase voltage. When the maximum d-axis control voltage (V) d ) exceeds the peak phase voltage, i.e., when V d > V S , then the derived scale Vd,sc=VSVd. However, if the maximum q-axis control voltage V q the peak phase voltage V S if it exceeds the integrator scale Vd,sc=VSVd. Otherwise, the integrator scale is V q,scequals 1. Both the output voltage limit and the integrator scale (V) q,sc ) use the peak phase voltage (V S The peak phase voltage (V S However, this varies with the machine temperature. With a low-voltage starter 18, such as a 12 V starter, the phase voltage drop through the cables and battery, e.g., a 1 V difference between a cold and a hot motor 20, has a noticeable effect. The controller 50 therefore uses the following compensation to minimize the temperature effect: VS=VB−IPH(RC+RB) where V B the voltage of battery pack 14 is, I PH the phase current on the AC bus 17 is, R C the resistance of a cable length connecting the battery pack 14 to the PIM 16, and R B The internal resistance of battery pack 14 is, where R C and R B These are all temperature-dependent values.

[0037] As in Fig. As shown in Figure 3, the illustrated logic 150L can include a q-axis control loop 150q and a d-axis control loop 150d, where the control loops 150q and 150d are cross-coupled as shown below. In the q-axis control loop 150q, a q-axis feedback current (I) is applied. q,FB ) from a q-axis current command (I q ) is subtracted at node 45 to generate a modified q-axis current instruction 46. The modified q-axis current instruction 46 is then converted into a temperature-independent proportional gain (Kpq) block 54 and an integrator block. (1S) The output of the proportional gain block 52 is fed into a saturation block 58, which in turn applies calibrated upper and lower limits to the output of the proportional gain block 54. This limited voltage value (V1) is fed into a further summing block 64.

[0038] The output of integrator block 52 is connected together with the aforementioned integrator scale (V q,SC ) is fed into a limiter block 152. Like the saturation block 58 described above, the limiter block 152 applies upper and lower limits to the output of the integrator block 52 in the integral control loop of the q-axis control loop 150q shown. The output of the integrator block 52 is connected together with the integrator scale (V q,SC ) is multiplied at multiplier block 55, the result being processed by separate integral gains in blocks 56 and 57. Integrator gain block 57 is a cross-coupled gain block independent of machine temperature, while integrator block 56 is a temperature-dependent gain value, both values ​​possibly extracted from a lookup table in the memory (M) of controller 50 or retrieved by controller 50 using processor (P) of Fig. 1 will be calculated.

[0039] The output (curve 60) of the temperature-independent integrator gain block 57 is fed to node 161 as a cross-feedback term in the d-axis control loop 150d. Simultaneously, the output of the integrator gain block 56 is added to another cross-feedback term output by the d-axis control loop 150d (curve 160), as explained below. The sum at node 61 is fed as a further voltage value V2 into the summing node 164 and added to the limited output of the saturation block 58, i.e., to the aforementioned voltage value V1.

[0040] An additional input to the summing block 64 is a temperature-dependent terminal voltage value, calculated by the controller 50 to correctly compensate for temperature effects on the magnetic flux density of the starter 18. The magnetic flux density varies by approximately 30% over a typical operating temperature range of the starter 18. For example, the flux density can be approximately 1.29 at -40 °C and drop to approximately 1 at 180 °C. Since the flux linkage is directly related to the magnetic flux density, the controller 50 is configured to directly compensate for such temperature-based changes in the flux linkage at the flux linkage block 62.

[0041] That is, using the flux linking block 62, the controller 50 multiplies the product of the angular velocity of the rotor 19 of the brushless starter 18 (see Fig. 1), i.e. N 18 from Fig. 1 and λ, i.e., a flux leakage constant, which is taken from a lookup table based on the machine temperature or calculated in real time based on changes in the machine temperature. Thus, the flux linkage block 62 determines the product of angular velocity and flux linkage to generate the back EMF of the starter 18 as the third voltage value V3.

[0042] The final output voltage of the summing block 64, i.e., V1 + V2 + V3, can be used by the controller 50 as a synchronous q-axis control voltage (Vq). The controller 50 can control the internal switching operation of the PIM 16. Fig. 1 control to set the synchronous q-axis control voltage (V q ) to apply to the brushless starter 18, as is estimated by a professional.

[0043] Fig. Figure 3 also shows the implementation for the d-axis. That is, the feedback current (I d,FB ) is controlled by the d-axis current command (Iq ) at node 145 to generate a modified d-axis current instruction 146. The modified d-axis current instruction 146 is divided into a temperature-independent proportional gain (Kpd) block 154 and an integrator block. (1S) The output of the proportional gain block 152 is fed into a saturation block 158, which applies calibrated upper and lower limits to the output of the proportional gain block 154. This limited voltage value (V4) is fed into a summing block 164.

[0044] The output of integrator block 152 is connected together with the aforementioned derivation scale (V d,SC ) is fed into a limiter block 252, which applies the upper and lower limits to the output of the integrator block 152. The output of the integrator block 152 is connected together with the derivative scale (V d,SCThe value is multiplied at multiplier block (X) 155, and this result is processed by separate integral gain blocks 156 and 157. Gain block (Kidc) 157, like block 57 in the q-axis control loop 150q, is a cross-coupled gain block independent of the machine temperature. Block 156 applies a temperature-dependent gain value, with the gains of blocks 156 and 157 possibly extracted from a lookup table stored in the memory (M) of the controller 50 or calculated by the controller 50. The output (curve 160) of the integrator gain block 157 is then fed into node 61 of the q-axis control loop 150q. At the same time, the output (curve 60) of block 57 within the q-axis control loop 150q is subtracted from the output of block 156 within the d-axis control loop 150d at node 161.The difference at node 161 is fed to the summing node 164 as a further voltage value V5 and added at the summing node 164 to the limited output of the saturation block 158, i.e. the voltage value V4.

[0045] The final output voltage of the summing block 164 within the d-axis control loop 150d, i.e. V4+ V5, is then used by the controller 50 as a synchronous d-axis control voltage (V d ) used. The controller 50 can control the internal switching operation of the PIM 16 from Fig. 1 control to provide the synchronous d-axis control voltage (V d ) to apply to the brushless starter 18, as is estimated by a professional.

[0046] Fig. 4 is a flowchart showing one possible embodiment of method 100 for controlling the machine temperature of the in Fig. Figure 1 describes the brushless starter 18 shown. Typically, the starter 18 comprises stator windings and a permanent magnet or a conductive rod inside the rotor 19. The permissible operating temperature of the starter 18 is essentially determined by the material properties of these hardware components. Therefore, the Fig. 1 The control unit 50 shown is configured to automatically limit the machine temperature by means of active torque control of the starter 18 in order to protect the hardware components of the starter 18 from undesirable temperature effects, especially when operating under low speed / high torque conditions.

[0047] From step S102 of Fig. 4 determines the controller 50 after the initialization (**) of the controller 50 of Fig. 1 the machine temperature, e.g. by direct measurement with the temperature sensors 11 to output the temperature signal (T 18) or by estimation using a state observer. Method 100 continues with step S104 after determining the machine temperature.

[0048] Step S104 involves comparing the machine temperature determined in step S102 with a first temperature, i.e., a first calibrated threshold (CAL1). The first temperature can be a maximum operating temperature just before a higher shutdown temperature limit, as described in step S106, e.g., at the upper end of a normally permissible operating temperature range. If the machine temperature exceeds the first temperature, procedure 100 continues with step S106. If the machine temperature is lower than the first temperature, procedure 100 terminates.

[0049] In step S106, the controller 50 then compares the temperature signal (T). 18) or an estimated variation thereof indicating the machine temperature, with a second temperature, i.e., a second calibrated threshold (CAL2), corresponding to a maximum permissible machine temperature. The second temperature may correspond to a maximum temperature above which the performance and / or structural integrity of the starter 18 is likely to be impaired. If the machine temperature from step S102 exceeds the second temperature, procedure 100 proceeds to step S108. Otherwise, procedure 100 proceeds to step S110.

[0050] At step S108, the controller 50 enforces a condition in which the motor torque (T) M ), which is controlled by the brushless starter 18, is set to zero. The execution of step S108 effectively aborts or prevents the further execution of an auto-start event of the motor 20 in order to protect the hardware of the electric starter system 12. Fig. 1 to protect. In conjunction with this control action, the controller 50 can record a diagnostic code in its memory (M) indicating the aborted autostart event and take other actions, such as notifying a powertrain operator 10. Fig. 1 with a text message and / or an indicator signal. Procedure 100 is thus completed (***).

[0051] Step S110 involves controlling a level of machine power (P M ) from the starter motor 18 of Fig. 1 at a limited level, i.e. P M = LIM. Step S110 may involve applying a multiplier to a normal power level of the brushless starter 18, the multiplier possibly being extracted by the controller 50 from a lookup table indexed or referenced by the machine temperature or a delta temperature with respect to a starting temperature.

[0052] Using the above-described method 100 in conjunction with the electric starter system 12 of Fig. 1. The PI control described above can be implemented by a control loop in which the temperature effects on the brushless starter motor 18 are taken into account. Fig. 1. Special consideration should be given to this. Within the framework of Fig. The applied integral gain is temperature-dependent, taking into account the effects of temperature on the rotor flux and the machine resistance. Ultimately, the controller 50 selectively limits the output power of the starter 18 during an automatic start of the engine 20, using the factors described above, to protect the components of the hardware of the electric starter system 12.

[0053] While some of the best embodiments and other types have been described in detail, there are various alternative designs and embodiments for implementing the present teachings, which are defined in the appended claims. Those skilled in the art will recognize that modifications can be made to the disclosed embodiments without altering the scope of protection afforded by the present disclosure. Furthermore, the present concepts expressly include combinations and partial combinations of the described elements and features. The detailed description and drawings are supporting and descriptive of the present teachings, the scope of which is defined exclusively by the claims.

Claims

[1] Electric starter system (12) for use with an internal combustion engine (20) having a flywheel (32), wherein the electric starter system (12) comprises: a brushless starter (18) with a machine temperature; a pinion gear (33); an electromagnet (21) which can be operated to translate the pinion into engagement with the flywheel (32) in order to connect the brushless starter (18) with the flywheel (32) in response to a requested engine start event; and a controller (50) programmed with a temperature control logic (150L) that has a proportional-integral (PI) torque control loop; wherein the execution of the temperature control logic (150L) by the controller (50) in response to the requested motor start event, when the machine temperature is greater than a first temperature, causes the controller (50) to determine a required starting torque of the brushless starter (18) via the PI torque control loop at a level that reduces the machine temperature below the first temperature, to control the electromagnet (21), to shift the pinion gear (33) into engagement with the flywheel (32), and to control the delivery of the required starting torque by the brushless starter (18) to the internal combustion engine (20). [2] Electric starter system (12) according to claim 1, wherein the controller (50) is configured to abort the requested motor start event via the PI torque control loop if the machine temperature is higher than a second temperature which exceeds the first temperature. [3] Electric starter system (12) according to claim 1, wherein the brushless starter (18) is electrically connected to an inverter module (PIM), and wherein the controller (50) is further configured to generate or control pulse width modulation of the PIM to provide the required starting torque at the level that reduces the machine temperature below the first temperature. [4] Electric starter system (12) according to claim 1, further comprising at least one temperature sensor (11) arranged on or in the brushless starter (18) and configured to measure the machine temperature. [5] Electric starter system (12) according to claim 1, wherein a state observer is provided in the control (50) which can be operated to estimate the machine temperature in real time. [6] Electric starter system (12) according to claim 1, wherein the PI torque control loop uses a q-axis current command, a d-axis current command, a q-axis feedback current value and a d-axis feedback current as inputs, applies an integral gain that is indicated or referenced by the machine temperature, and generates a q-axis voltage command and a d-axis voltage command to the starter (18) as outputs. [7] Electric starter system (12) according to claim 6, wherein the PI torque control loop also includes a flux linking block which calculates a back electromotive force of the starter (18) as the product of an angular velocity and a flux leakage value of the starter (18), wherein the flux leakage value is based on the machine temperature, and wherein the controller (50) is configured to calculate the q-axis voltage command using the back electromotive force. [8] Method (100) for controlling the temperature of an electric starter system (12) with a brushless starter (18), wherein the method (100) comprises: Detection of a requested engine start event of an internal combustion engine (20) via a control unit (50), wherein an electromagnet (21) translates a pinion gear (33) into engagement with the brushless starter (18) and the internal combustion engine (20); Determining a machine temperature of the brushless starter (18) using the control (50); In response to the requested engine start event, when the machine temperature is greater than a first temperature, a required starting torque of the starter (18) is determined using a proportional-integral torque control loop of the controller (50), wherein the required starting torque is a value that limits an output power level of the starter (18) to a level sufficient to reduce the machine temperature below the first temperature; and Transmitting a torque command to the starter (18) to cause the starter (18) to transmit the required starting torque via the pinion gear (33) to the flywheel (32) of the internal combustion engine (20). [9] Method (100) according to claim 8, further comprising determining a q-axis current command, a d-axis current command, a q-axis feedback current value and a d-axis feedback current value as control inputs into the proportional-integral torque control loop via the controller (50), applying an integral gain that is indicated or referenced by the machine temperature, and generating a q-axis voltage command and a d-axis voltage command to the starter via the controller as control outputs. [10] Method (100) according to claim 9, further comprising: Using a flux linking block of the PI control loop to calculate a back electromotive force of the starter as the product of an angular velocity and a flux leakage value of the starter, where the flux leakage value is based on the machine temperature; and Calculating the q-axis voltage command using the counter-electromotive force.

Images