Vehicle control device

Abstract

To provide a technique capable of performing temperature estimation of a power conduction element with high accuracy even just after the start of the temperature estimation in a vehicle control device capable of estimating a temperature of the power conduction element by a temperature sensor arranged therearound.SOLUTION: In a vehicle control device 2, when starting estimation of a temperature of power conduction elements 4a and 4b, in the case where there is no abnormality in reading of a RAM 3c at the start, the estimation is started after an estimation temperature stored in the RAM 3c at the previous estimation termination is set to an estimation temperature of the power conduction elements 4a and 4b at the estimation start. On the other hand, in the case where there is an abnormality in reading of the RAM 3c, a value of a power conduction element estimation temperature worst which is set in accordance with a detection temperature of a thermistor 5 at the estimation restart is read from a ROM 3b, and the estimation is started after the value is set as the estimation temperature of the power conduction elements 4a and 4b at the estimation restart.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present invention relates to a vehicle control device that controls an actuator such as a motor provided in a host vehicle. [Background technology]

[0002] A MOSFET or other energizing element is mounted on the control board of various ECUs that control actuators such as motors arranged in a vehicle. When such an energizing element is provided in the transmission path of the actuator, when a large current flows through the actuator, the energizing element also generates a large amount of heat. As a result, problems such as deterioration of the performance of the energizing element, shortening of its life, or even destruction may occur. In order to prevent such problems, it is common to limit the energization so that the temperature of the energizing element does not exceed a predetermined temperature. In this case, it is necessary to grasp the temperature of the energizing element, but it may be difficult to attach a temperature sensor to the energizing element due to costs and layout. In the case where a temperature sensor cannot be attached directly to the energizing element, a temperature sensor is attached around the energizing element, and the temperature of the energizing element is estimated based on the temperature detected by the temperature sensor.

[0003] In such a method for estimating the temperature of an energized element, the accuracy of the temperature estimation becomes stable as the duration of the estimation becomes longer, but there is a problem in that the accuracy of the estimation is not stable immediately after the start of the estimation. In view of this, a technique has been proposed in the past in which, when the temperature estimation of the energized element is terminated, the estimated temperature is stored in a storage means such as a memory, and when the temperature estimation is resumed, the estimated temperature at the time of the previous termination is set as the initial value of the estimated temperature value of the energized element (see, for example, Patent Document 1). In this way, it is possible to improve the accuracy of the estimation of the temperature of the energized element immediately after the start of the estimation. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] International Publication No. 2008 / 153162 Summary of the Invention [Problem to be solved by the invention]

[0005] However, the technology described in Patent Document 1 above had the problem that it became difficult to estimate the temperature if there was an abnormality in writing the estimated temperature to the memory means when temperature estimation of the energized element was terminated, or if there was an abnormality in reading the data when temperature estimation was resumed.

[0006] The present invention has been made in consideration of the above-mentioned problems, and aims to provide a technology in a vehicle control device capable of estimating the temperature of an energized element using a temperature sensor arranged around it, which can accurately estimate the temperature of an energized element even immediately after temperature estimation has begun. [Means for solving the problem]

[0007] In order to achieve the above-mentioned object, the vehicle control device of the present invention comprises a temperature sensor that detects an ambient temperature, a first temperature estimation means that estimates the temperature of each of a plurality of energized elements arranged around the temperature sensor based on the ambient temperature detected by the single temperature sensor, a read / write means that reads and writes the estimated temperatures of the plurality of energized elements estimated by the first temperature estimation means to a memory, a storage means that stores, for each of the plurality of energized elements, an expected temperature of the energized element predicted according to the ambient temperature detected by the temperature sensor, and a second temperature estimation means that starts estimating the temperature of the plurality of energized elements when a predetermined temperature estimation start condition is met after the temperature estimation by the first temperature estimation means is completed, and is characterized in that, if there is no abnormality in reading and writing to the memory, the second temperature estimation means starts estimating the temperature of each of the plurality of energized elements based on the estimated temperature at the end of the estimation by the first temperature estimation means that was written to the memory, while if there is an abnormality in reading and writing to the memory, it reads from the storage means the expected temperature of the energized element that corresponds to the ambient temperature detected by the temperature sensor at the start of the estimation, and starts estimating the temperature of each of the plurality of energized elements based on the read expected temperature of the energized element (Claim 1). Effect of the Invention

[0008] According to the invention of claim 1, when the temperature estimation of the energized elements is once terminated and resumed, if there is no abnormality in reading and writing the memory, the second temperature estimation means starts estimating the temperature of each energized element based on the estimated temperature at the time of the previous end of estimation, which was written in the memory. This allows the temperature of each energized element to be estimated accurately even immediately after the start of temperature estimation. Furthermore, if there is an abnormality in reading and writing the memory, the second temperature estimation means reads out from the storage means the energized element predicted temperature predicted according to the temperature detected by the temperature sensor at the time of the start of estimation, and starts estimating the temperature of each energized element based on the read energized element predicted temperature. This allows the second temperature estimation means to estimate the temperature of each energized element accurately even if there is an abnormality in reading and writing the memory. Furthermore, since the temperatures of multiple energized elements are estimated using a single temperature sensor, the cost of temperature estimation can be reduced. [Brief description of the drawings]

[0009] [Figure 1] 1 is a schematic configuration diagram of a vehicle control device according to an embodiment of the present invention; [Diagram 2] 1 is a time chart for explaining an example of temperature estimation of a current-carrying element according to a conventional technique. [Diagram 3] 6 is a time chart for explaining a comparative example of temperature estimation of a current-carrying element; [Figure 4] 5 is a time chart for explaining an example of temperature estimation of an energization element according to the present embodiment. [Diagram 5] FIG. 11 is a diagram showing the relationship between the thermistor temperature of each energization element and the worst estimated energization element temperature in this embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] A vehicle control device according to one embodiment of the present invention will be described with reference to Figures 1 to 5. Figure 1 is a schematic diagram of a vehicle control device according to one embodiment of the present invention, Figures 2 and 3 are time charts for explaining an example of current limitation to current-carrying elements in the prior art and comparative examples, Figure 4 is a time chart for explaining an example of current limitation to current-carrying elements in this embodiment, and Figure 5 is a diagram showing the relationship between thermistor temperature of each current-carrying element in this embodiment and the worst estimated current-carrying element temperature.

[0011] (Vehicle Electrical Configuration) A vehicle control device 2 (hereinafter, sometimes referred to as ECU 2) according to one embodiment of the present invention controls the operation of an actuator such as a motor M arranged in a vehicle 1, and includes a microcomputer 3, a plurality of current-carrying elements 4a, 4b (two in this embodiment), a current detection circuit 6, and a thermistor 5. The microcomputer 3, current-carrying elements 4a, 4b, and thermistor 5 are mounted on a control board (not shown) of the ECU 2. The current detection circuit 6 can be formed by the specifications of the various elements, the combination of the various elements, and the layout thereof.

[0012] The vehicle 1 of this embodiment is, for example, an electric vehicle using a motor as a drive source, and the ECU 2 is, for example, an EVP (Electric Vacuum Pump)-ECU that controls an electric vacuum pump that generates brake negative pressure for the electric vehicle. In this case, the ECU 2 controls the driving of the motor of the electric vacuum pump. This generates a negative pressure (brake negative pressure) in place of the engine negative pressure used for the brake booster in the electric vehicle.

[0013] As shown in FIG. 1, the ECU 2 is connected to a power source 7 such as a battery, a ground, and a motor M, and has a power source terminal Ta connected to the power source 7 such as a battery, a first motor connection terminal Tb connected to one end of the motor M, a second motor connection terminal Tc connected to the other end of the motor M, and a ground terminal Td connected to ground.

[0014] The microcomputer 3 performs various controls such as controlling the supply of current to the motor M, and is equipped with a CPU 3a (corresponding to the "first temperature estimation means," "second temperature estimation means," and "read / write means" of the present invention) that performs calculations related to the controls, a ROM 3b (corresponding to the "storage means" of the present invention) that stores various control programs and the worst value of the estimated temperature of the energized elements used to estimate the temperature of the energized elements 4a and 4b described below, and a RAM 3c (corresponding to the "memory" of the present invention) which is a non-volatile memory that temporarily stores the estimated temperatures calculated by the CPU 3a, etc.

[0015] The energization elements 4a, 4b (corresponding to the "energization element" of the present invention) function as switches capable of turning on and off the energization of the motor M, and in this embodiment, both are formed of MOSFETs (metal oxide semiconductor field effect transistors). As shown in FIG. 1, the energization element 4a, which is one of the energization elements 4a, 4b, has, for example, a drain terminal connected to a power supply terminal Ta of the ECU 2 and a source terminal connected to a first motor connecting terminal Tb of the ECU 2. The energization element 4b, which is the other of the energization elements 4a, 4b, has, for example, a drain terminal connected to a second motor connecting terminal Tc of the ECU 2 and a source terminal connected to a ground terminal Td.

[0016] In this embodiment, MOSFETs are used as switching elements as an example of the energizing elements 4a and 4b, but the present invention is not limited to this. For example, switching elements such as switch ICs such as IPDs (Intelligent Power Devices), bipolar transistors, and thyristors can be used. The energizing elements 4a and 4b may be the same type of switching element or different types of switching elements.

[0017] The ON / OFF setting of each energizing element 4a, 4b is controlled by the CPU 3a of the microcomputer 3. For example, when a voltage is supplied to both gate terminals of the energizing elements 4a, 4b under the control of the CPU 3a, both energizing elements 4a, 4b are set to ON, and a current flows from one end side (the first motor connection terminal Tb side) to the other end side (the second motor connection terminal Tc side) of the motor M (motor drive control). On the other hand, when a voltage is not supplied to at least one of the gate terminals of the energizing elements 4a, 4b under the control of the CPU 3a, one of the energizing elements 4a, 4b is set to OFF, and no current flows through the motor M (motor drive stop control). Note that when performing motor drive stop control, the CPU 3a may control only one of the energizing elements 4a, 4b to be set to OFF, or may control both of the energizing elements 4a, 4b to be set to OFF.

[0018] The current detection circuit 6 detects the value of a current flowing through the motor M and the energizing elements 4a, 4b, and is disposed in the middle of a transmission path connecting the energizing element 4a and the first motor connection terminal Tb on the control board of the ECU 2. The current value detected by the current detection circuit 6 is input to the CPU 3a of the microcomputer 3. The CPU 3a stores the current value detected by the current detection circuit 6 in the RAM 3c, and counts the energization time (energization duration).

[0019] The arrangement of the current detection circuit 6 can be changed as appropriate. For example, it may be arranged on the transmission path connecting the power supply terminal Ta and the energizing element 4a, or on the transmission path connecting the second motor connecting terminal Tc and the energizing element 4b. It may also be arranged on the transmission path connecting the energizing element 4b and the ground terminal Td. Furthermore, a plurality of current detection circuits may be arranged, for example, by arranging another current detection circuit on the transmission path connecting the second motor connecting terminal Tc and the energizing element 4b. When a plurality of current detection circuits are arranged, even if one current detection circuit stops functioning, the other current detection circuits can detect the current.

[0020] The thermistor 5 (corresponding to the "temperature sensor" of the present invention) detects the temperature around a resistor element of the thermistor 5, and is mounted on a control board of the ECU 2. A signal indicating the ambient temperature detected by the thermistor 5 is input to the CPU 3a of the microcomputer 3.

[0021] In this way, the energizing elements 4a and 4b are arranged as switch elements on the transmission path of the current flowing through the motor M. In this case, when a large current flows through the motor M, a large current also flows through the energizing elements 4a and 4b. When a large current flows through the energizing elements 4a and 4b, the elements 4a and 4b generate a large amount of heat. In various components including the energizing elements 4a and 4b and the current detection circuit 6, problems such as performance degradation and shortened lifespan may occur when the temperature becomes high. Therefore, the CPU 3a limits the energization of the energizing elements 4a and 4b so that the energizing elements 4a and 4b do not exceed a specified temperature (hereinafter referred to as the "energization limit temperature"). The energization of the motor M is also limited by the energization limit.

[0022] This current limit temperature is a temperature at which the above-mentioned problems do not occur in various components including the energizing elements 4a, 4b and the current detection circuit 6, and an upper limit operating temperature determined according to the type of the energizing elements 4a, 4b can be used. Therefore, when the types of various components such as the energizing elements 4a, 4b are different, the current limit temperature is also different. Note that the CPU 3a performs current limiting when one of the energizing elements 4a, 4b reaches the current limiting temperature. In this embodiment, current limiting means stopping the current flowing to the motor M or suppressing the amount of current. In the following, a case where the current flowing to the motor M is stopped will be described as an example of current limiting.

[0023] (Temperature Estimation) In order to limit the current supply to the motor M, it is necessary to detect the temperatures of the energizing elements 4a and 4b. In this embodiment, the temperatures of the energizing elements 4a and 4b are estimated based on the ambient temperature detected by the thermistor 5, the current values ​​flowing through the energizing elements 4a and 4b, and the energizing time (current supply duration). Specifically, the heat generation amount of each of the energizing elements 4a and 4b is estimated based on the current values ​​flowing through the energizing elements 4a and 4b and the energizing time (current supply duration), and the estimated temperature of each of the energizing elements 4a and 4b is calculated based on the ambient temperature detected by the thermistor 5 and the estimated heat generation amount of each of the energizing elements 4a and 4b. The CPU 3a of the microcomputer 3 estimates the heat generation amount of each of the energizing elements 4a and 4b and calculates the estimated temperature. The calculation of the estimated temperature is performed at a predetermined cycle on the condition that the vehicle 1 is powered on. The calculated estimated temperatures of the energizing elements 4a and 4b are written to a predetermined storage area of ​​the RAM 3c by the CPU 3a, and the estimated temperatures in the predetermined storage area are updated at predetermined intervals. The estimated temperatures of the energizing elements 4a and 4b are stored separately and updated at predetermined intervals.

[0024] The heat generation amount of each current-carrying element 4a, 4b can be estimated, for example, from the thermal resistance (Rth) of the element 4a, 4b and the power consumption of the element 4a, 4b. Here, the power consumption amount = the power consumption (P) of the element 4a, 4b × the current-carrying time (continuous current-carrying time). Therefore, if the current value of the element 4a, 4b is I [A] and the resistance value of the element 4a, 4b is R [Ω], the power consumption (P) is expressed as follows: P = I 2 ×R. Since the thermal resistance (Rth) and resistance value (R) of the energization elements 4a, 4b are known values, the heat generation amount of the energization elements 4a, 4b can be estimated by detecting the value of the current flowing through the energization elements 4a, 4b and the energization time. Here, the current value detected by the current detection circuit 6 can be used as the current value of the energization elements 4a, 4b. The energization time can be managed, for example, by a counter set in a predetermined area of ​​the RAM 3c of the microcomputer 3.

[0025] The CPU 3a also calculates the estimated temperatures of the energized elements 4a, 4b based on a predetermined calculation formula (hereinafter referred to as the "estimated element temperature calculation formula"). The estimated element temperature calculation formula includes, for example, the ambient temperature detected by the thermistor 5 and the estimated heat generation amount of the energized elements 4a, 4b described above, and calculates the temperatures of the energized elements 4a, 4b based on these. The estimated element temperature calculation formula is provided individually for each of the energized elements 4a, 4b.

[0026] The element estimated temperature calculation formula for each energized element 4a, 4b can be corrected based on the difference between the simulation result by the provisional calculation formula set and the actual temperature of the energized elements 4a, 4b by an experiment or the like, and the provisional calculation formula with the smallest difference can be adopted as the element estimated temperature calculation formula. In this embodiment, the temperature of each energized element 4a, 4b is calculated using the calculation formula, but the calculation formula includes the estimated heat generation amount of each energized element 4a, 4b as described above. Therefore, the calculation of the temperature of each energized element 4a, 4b using the calculation formula can be said to estimate the temperature of each energized element 4a, 4b. Therefore, hereinafter, the temperature calculated using the calculation formula may be referred to as the estimated temperature of the energized elements 4a, 4b.

[0027] This element estimated temperature calculation formula is a calculation formula that takes into account other factors that affect the temperature of the energized elements 4a, 4b, in addition to the ambient temperature detected by the thermistor 5 and the estimated heat generation amount of the energized elements 4a, 4b described above. The other factors include, for example, the distance between the energized elements 4a, 4b to be estimated and the thermistor 5, the surrounding environment of the energized elements 4a, 4b, and the thermal conductivity of the energized elements 4a, 4b. Here, the surrounding environment of the energized elements 4a, 4b includes the type of components, such as whether the components mounted around the energized elements 4a, 4b are heat-generating components, the arrangement of the wiring patterns formed around the energized elements 4a, 4b, and the presence or absence of a heat dissipation member around the energized elements 4a, 4b. In the element estimated temperature calculation formula, for example, the ambient temperature detected by the thermistor 5 and the estimated heat generation amount of the energized elements 4a, 4b to be calculated (estimated based on the current value of the energized elements 4a, 4b and its energization time) are used as variables, and other elements are reflected as constants. Note that the correction of the provisional calculation formula performed when determining the element estimated temperature calculation formula means the correction of the constants.

[0028] In such a method of calculating (estimating) the temperature of the energized elements 4a and 4b, the accuracy of the estimation becomes stable as the duration of the estimation becomes longer, but there is a problem that the estimation accuracy is not stable immediately after the start of the estimation. As a result, for example, if the temperature of the energized elements estimated immediately after the start is lower than the actual temperature of the energized elements, a malfunction may occur in which the energization is not limited even though the temperature is higher than the energization limit temperature. Therefore, in this embodiment, when the temperature estimation of the energized elements 4a and 4b is resumed, the temperature is calculated (estimated) by a method different from the temperature calculation (estimation) by the element estimated temperature calculation formula, so that the above malfunction does not occur. As for such a malfunction when the temperature calculation (estimation) is resumed, measures are taken in the conventional technology and the comparative example as described below, but in this embodiment, the temperature of the energized elements at the start (resumption) is estimated by a method different from that in the conventional technology and the comparative example. Note that the function of the CPU 3a to estimate the temperature of the energized elements 4a and 4b using the element estimated temperature calculation formula corresponds to the "first temperature estimation means" of the present invention.

[0029] Next, referring to Fig. 2 and Fig. 3, a conventional technique and a comparative example of a method for estimating the temperature of a current-carrying element and an example of current-carrying limitation using the estimated temperature will be described, and the problems associated with the method and current-carrying limitation will be described. Then, referring to Fig. 4 and Fig. 5, an example of a method for estimating the temperature of a current-carrying element and current-carrying limitation of the present embodiment will be described. Fig. 2 is a diagram for explaining the conventional technique that solves the above-mentioned problem, and Fig. 3 is a diagram for explaining a comparative example that solves the problem of the conventional technique of Fig. 2.

[0030] (Current Limitation in the Prior Art) Fig. 2 showing the conventional technology shows a timing chart for each item, such as the ON / OFF state of the system power supply (power supply of the vehicle), whether or not current is being supplied to the motor, whether or not current is being limited to the motor, the ambient temperature detected by the thermistor, the estimated temperature of the current-carrying element (estimated element temperature), the actual temperature of the current-carrying element (actual element temperature), and the estimated temperature of the current-carrying element stored in a storage means such as a RAM (estimated non-volatile memory storage element temperature). Fig. 3 showing a comparative example and Fig. 4 showing this embodiment also show timing charts for the same items as Fig. 2.

[0031] As shown in FIG. 2, in the initial state (before time T1), the vehicle power supply is ON and current is being applied to the motor. Also, for example, the estimated temperature of the current-carrying element (estimated element temperature) is lower than the current-carrying limit temperature, and as a result, no current-carrying limit is being applied. This state continues until T1. At time T1, it is assumed that current to the motor is stopped with no current-carrying limit being applied. Accordingly, after time T1, the actual thermistor temperature, estimated element temperature, and actual element temperature each gradually decrease. Then, at time T2, the vehicle power supply is set to OFF. At this time, the temperature of the current-carrying element estimated at time T2 is written to memory.

[0032] After that, at time T3, the vehicle power supply is set to ON, and accordingly, estimation of the temperature of the energized element is restarted. At this time, the estimated temperature written in the memory at time T2 is read out, and the read temperature is set as the estimated temperature when estimation is restarted.

[0033] Since no current flows through the energized elements 4a and 4b between time T2 and time T3, the temperatures of the energized elements 4a and 4b at time T3 when the temperature estimation is resumed are considered to be lower than the temperatures at the end of the previous estimation (time T2). Therefore, in the conventional technology, the estimated temperatures of the energized elements 4a and 4b at time T3 are set to the estimated temperatures at the end of the previous estimation (time T2), thereby avoiding a problem in which, for example, energization after time T3 causes the actual element temperature to become higher than the energization limit temperature, but energization is not limited.

[0034] At time T4, current is applied to the motor, and as a result, the actual thermistor temperature, estimated element temperature, and actual element temperature all rise from time T4 onwards. As current continues to be applied to the motor from time T4 onwards, the estimated element temperature reaches the current limit temperature at time T5. At this time, current is stopped to the motor and the current-carrying elements. If, as a result of the continuation of the current limit, the estimated element temperature drops to the return temperature for lifting the current limit at time T6, the current limit is lifted.

[0035] In the configuration of the conventional technology, if there is an abnormality in writing the estimated temperature of the energization element to the memory at time T2, or if there is an abnormality in reading the estimated temperature from the memory at time T3, it is not possible to read the estimated temperature at the time of the previous termination, and therefore it may not be possible to appropriately limit energization. Such abnormalities in reading and writing the estimated temperature to the memory can be addressed by taking the following comparative example.

[0036] (Comparative Example Current Limitation) Next, the current restriction of the comparative example will be described with reference to FIG. 3. Note that the comparative example is also the same from time T1 to T2. That is, at time T2, the power supply of the vehicle is set to OFF. Also, at time T2, the estimated temperature of the energizing element is written to the memory. At this time, it is assumed that there is an abnormality in writing the estimated temperature to the memory or an abnormality in reading from the memory. After that, when the power supply of the vehicle is set to ON at time T3, estimation of the temperature of the energizing element is resumed. However, because there is an abnormality in reading and writing from the memory, it is not possible to read the estimated temperature at the time of the previous estimation end (time T2) from the memory and set the estimated temperature as the estimated temperature of the energizing element when the estimation is resumed (time T3) as in the conventional technology. Therefore, in the comparative example, if there is an abnormality in writing the estimated temperature at time T2 or an abnormality in reading the estimated temperature at time T3, a predetermined temperature is set as the estimated temperature of the energizing element when the estimation is resumed (time T3). This predetermined temperature is an estimated temperature that is determined in advance as an estimated temperature to be used in the case where an abnormality occurs in reading and writing the memory, and is stored in a storage means such as a ROM. Note that this predetermined temperature is set to, for example, a temperature equal to or higher than the current limit temperature.

[0037] In this way, if there is an abnormality in reading and writing the memory, a temperature (predetermined temperature) equal to or higher than the current-carrying limit temperature is set. Therefore, at time T3, current to the motor and current-carrying elements is restricted, and estimation of the temperature of the current-carrying elements is resumed. Then, for example, at time T7, when the estimated temperature of the current-carrying elements falls to the recovery temperature defined as the temperature at which the current-carrying limit is released, the current-carrying limit is released.

[0038] According to the configuration of the comparative example, if there is an abnormality in reading and writing the memory, the estimated temperature of the energized element when estimation is resumed (time T4) is always set to be equal to or higher than the energization limit temperature. Therefore, as shown in Fig. 3, even if the temperature of the energized element (actual element temperature) when temperature estimation of the energized element is resumed (time T3) is equal to or lower than the energization limit temperature, energization limiting is performed, which may result in excessive protection of the energized element. Therefore, in this embodiment, the configuration is made to suppress excessive protection of the energized element as much as possible.

[0039] (Current Limitation in this Embodiment) Next, the current restriction of this embodiment will be described with reference to Fig. 4 and Fig. 5. In this embodiment, the process from time T1 to T2 is the same. That is, at time T2, the power supply of the vehicle 1 is set to OFF. At time T2, the estimated temperatures of the current-carrying elements 4a, 4b are written by the CPU 3a to a predetermined storage area of ​​the RAM 3c. Up until time T2, the temperatures of the current-carrying elements 4a, 4b are estimated by the CPU 3a based on the element estimated temperature calculation formula described above.

[0040] At time T3, the power supply of the vehicle 1 is set to ON (corresponding to "when a predetermined temperature estimation start condition is satisfied" of the present invention), and accordingly, the CPU 3a starts (resumes) estimating the temperatures of the energized elements 4a and 4b. At this time, the CPU 3a judges whether or not there is an abnormality in writing the estimated temperature at time T2, and whether or not there is an abnormality in reading the estimated temperature (estimated temperature of the energized elements 4a and 4b at time T2) stored in the RAM 3c at time T3. Here, if it is judged that there is no abnormality in both writing the estimated temperature at time T2 and reading the estimated temperature stored in the RAM 3c at time T3, the CPU 3a reads the estimated temperature at the time of the previous termination (time T2) stored in the RAM 3c, and sets the estimated temperature as the estimated temperature of the energized elements 4a and 4b after the estimation is resumed (time T3).

[0041] The temperature of the energizing elements 4a, 4b after the time T3 can be estimated based on, for example, the previous estimated temperature and the estimated heat generation amount of the energizing elements 4a, 4b from the previous time to the current time. The estimated heat generation amount can be calculated in the same manner as the estimated heat generation amount used in the element estimated temperature calculation formula. That is, the estimated heat generation amount can be estimated based on the thermal resistance (Rth) of the energizing elements 4a, 4b, the current value flowing through the energizing elements 4a, 4b, and the energization time. In addition, if there is no current flowing through the energizing elements 4a, 4b from the previous estimation to the current estimation, the estimated heat generation amount is configured to indicate a negative value. Therefore, if there is no current flowing through the energizing elements 4a, 4b from the previous estimation to the current estimation, the current estimated temperature is a value obtained by subtracting a predetermined value from the previous estimated temperature. This predetermined value can be calculated, for example, by experiment or the like.

[0042] On the other hand, if it is determined that there is an abnormality in at least one of the writing of the estimated temperature at time T2 and the reading of the estimated temperature stored in RAM 3c at time T3, the CPU 3a acquires the ambient temperature detected by the thermistor 5 at time T3, and sets the worst value of the energized element estimated temperature corresponding to the ambient temperature (corresponding to the ``energized element predicted temperature'' of the present invention) as the estimated temperature of the energized elements 4a, 4b after estimation is resumed (at time T3).

[0043] Fig. 4 illustrates a case where there is an abnormality in at least one of writing the estimated temperature at time T2 and reading the estimated temperature stored in RAM 3c at time T3. Fig. 4 also illustrates a case where the worst value of the energization element estimated temperature according to the temperature detected by thermistor 5 (actual thermistor temperature) at time T3 is lower than the energization limit temperature of energization elements 4a and 4b.

[0044] The worst current-carrying element estimated temperature value is the highest temperature that the current-carrying elements 4a, 4b can have with respect to the ambient temperature detected by thermistor 5. For example, if the ambient temperature detected by thermistor 5 is 50°C, this is the highest temperature that the current-carrying elements 4a, 4b can have at that temperature of 50°C. Therefore, it is considered that the actual temperatures (actual element temperatures) of the current-carrying elements 4a, 4b at time T3 are lower than the worst current-carrying element estimated temperature value. This worst current-carrying element estimated temperature value can be found, for example, by substituting the highest variable into the above-mentioned element estimated temperature calculation formula.

[0045] FIG. 5 shows an example of the relationship between the temperature detected by the thermistor 5 and the worst value of the energized element estimated temperature. The worst value of the energized element estimated temperature is affected by the thermal conductivity of the energized elements 4a and 4b, the distance from the thermistor 5, the type of components mounted in the vicinity (type of components such as whether they are heat-generating components or not), the layout of the wiring pattern formed in the vicinity, the presence or absence of a heat dissipation member disposed in the vicinity, and the like. Therefore, the worst value of the energized element estimated temperature is derived by experiment or design, taking these influences into consideration. Therefore, the worst value of the energized element estimated temperature of each of the energized elements 4a and 4b with respect to the temperature of the thermistor 5 is different. For example, in this embodiment, the energized element 4b is mounted at a position farther away from the energized element 4a than the mounting position of the thermistor 5. In the example of this embodiment shown in Figure 5, the worst conductive element estimated temperature value (Tae in Figure 5) of conductive element 4a at the temperature (Ts in Figure 5) detected by thermistor 5 is different from the worst conductive element estimated temperature value (Tbe in Figure 5) of conductive element 4b, and the worst conductive element estimated temperature value of the farther conductive element 4b is higher than the worst conductive element estimated temperature value of the closer conductive element 4a.

[0046] In this embodiment, the relationship between the temperature detected by the thermistor 5 and the worst value of the energization element estimated temperature is stored in the ROM 3b as a map (hereinafter, an abnormality temperature estimation map) for each of the energization elements 4a and 4b. If it is determined at time T3 that there is an abnormality in reading and writing to the RAM 3c, the CPU 3a reads out the worst value of the energization element estimated temperature corresponding to the ambient temperature detected by the thermistor 5 from the map, and sets the value as the estimated temperature of the energization elements 4a and 4b at time T3. The function of the CPU 3a to start estimating the temperature of the energization elements 4a and 4b using the worst value of the energization element estimated temperature at the start (restart) of temperature estimation (time T3) corresponds to the "second temperature estimation means" of the present invention.

[0047] The temperature of the energizing elements 4a, 4b after time T3 is estimated in the same manner as when there is no abnormality in reading and writing to the RAM 3c. That is, it is estimated based on the previous estimated temperature and the estimated heat generation amount of the energizing elements 4a, 4b from the previous estimation to the current estimation. Also, when there is no current flowing to the energizing elements 4a, 4b from the previous estimation to the current estimation, the estimated heat generation amount is configured to indicate a negative value, as in the case when there is no abnormality in reading and writing to the RAM 3c. Therefore, when there is no current flowing to the energizing elements 4a, 4b from the previous estimation to the current estimation, the current estimated temperature is a value obtained by subtracting a predetermined value from the previous estimated temperature.

[0048] Returning to the explanation of FIG. 4, when the power supply to the motor M is resumed at time T8, the estimated temperatures (estimated element temperatures) of the power supply elements 4a and 4b thereafter rise. When the power supply to the motor M is stopped at time T9, the estimated temperatures (estimated element temperatures) of the power supply elements 4a and 4b thereafter decrease. Note that in this example, the estimated temperatures (estimated element temperatures) of the power supply elements 4a and 4b have not yet reached the power limit temperature at time T9 when the power supply is stopped. As a result, this illustrates a case in which power limiting is not performed even once between times T1 and T9.

[0049] Therefore, according to the above embodiment, when the estimation of the temperature of the energized elements 4a, 4b is resumed (at time T3), if there is no abnormality in reading and writing from the RAM 3c, the estimated temperature stored in the RAM 3c at the end of the previous estimation (at time T2) is read, and the estimation of the temperature of the energized elements 4a, 4b is started (restarted) based on the estimated temperature. As a result, the estimated temperature at the end of the previous estimation is reflected, so that the estimation of the temperature of the energized elements 4a, 4b can be performed with high accuracy even immediately after the start of the estimation. In addition, since the estimation of the temperature of the energized elements 4a, 4b can be performed with high accuracy, it is possible to perform an appropriate current restriction according to the estimated temperature of the energized elements 4a, 4b.

[0050] Furthermore, if there is an abnormality in reading and writing from the RAM 3c at the time (time T3) when the estimation of the temperature of the energizing elements 4a and 4b is started (restarted), the worst value of the energizing element estimated temperature corresponding to the temperature (actual thermistor temperature) detected by the thermistor 5 at time T3 is read from the ROM 3b, and the estimation is started (restarted) with the worst value as the estimated temperature at the time of restarting the estimation (time T3). That is, if there is an abnormality in reading and writing from the RAM 3c, the highest (worst) temperature corresponding to the temperature detected by the thermistor 5 at the time of restarting the estimation (time T3) is set as the estimated temperature of the energizing elements 4a and 4b at time T3. Therefore, when an abnormality occurs in the memory, the temperature of the energizing elements 4a and 4b immediately after the start (restart) can be estimated more accurately than in the above-mentioned comparative example. Furthermore, since the estimation accuracy of the temperatures of the energizing elements 4a and 4b is improved, it is possible to avoid excessive protection in which the energization is restricted even when the actual temperature of the energizing elements (actual element temperature) is lower than the energization limit temperature, as in the comparative example described with reference to Fig. 3. As a result, it is possible to reduce the time that the power supply to the motor M is stopped, and the continuity of the system related to the operation of the motor M, such as the provision of brake negative pressure by the electric negative pressure pump, is improved.

[0051] Furthermore, since the temperature of each of the current-carrying elements 4a, 4b is estimated using a single thermistor 5, the cost involved in estimating the temperature of the current-carrying elements 4a, 4b can be reduced.

[0052] In this embodiment, the abnormality temperature estimation map is stored in a storage unit (ROM 3b) different from the RAM 3c. In this way, even if an abnormality occurs in reading and writing from the RAM 3c, the estimated temperature can be read from the normal ROM 3b. As a result, it is possible to continue estimating the temperatures of the energizing elements 4a and 4b after time T3.

[0053] The present invention is not limited to the above-mentioned embodiment, and various modifications are possible without departing from the gist of the present invention. For example, in the above-mentioned embodiment, the setting of the estimated temperature at the time of estimation start (restart) is described as a case where, when it is determined that there is an abnormality in reading and writing of the RAM 3c at the time of restart (time T3), the value of the worst energizing element estimated temperature is set as the estimated temperature of the energizing elements 4a, 4b. However, this value of the worst energizing element estimated temperature may be corrected according to the length of the time from when the system power is set to OFF to when it is set to ON (the time from time T2 to T3: 0FF duration). Specifically, the longer the 0FF duration, the lower the value of the worst energizing element estimated temperature may be corrected, and the shorter the 0FF duration, the higher the value of the worst energizing element estimated temperature may be corrected. In this case, if the 0FF duration is longer than a predetermined time, the value of the worst energizing element estimated temperature may be corrected to a low value, and if the 0FF duration is shorter than a predetermined time, the value of the worst energizing element estimated temperature may be corrected to a high value. As for the correction amount, for example, a map showing the relationship between the 0FF duration and the correction amount may be stored in the ROM 3b.

[0054] In addition, with regard to setting the estimated temperature at the start (resumption) of estimation, the CPU 3a determines whether the worst value of the energized element estimated temperature according to the detected temperature of thermistor 5 at the time estimation is resumed (time T3) is greater than the energization limit temperature of energized elements 4a, 4b, and if it is less than the energization limit temperature, estimation may be started by temperature calculation (estimation) using the above-mentioned element estimated temperature calculation formula, without setting the estimated temperature at the start of estimation (time T3) to the worst value of the energized element estimated temperature.

[0055] In addition, in the above embodiment, the CPU 3a is configured to estimate the temperature of the energized elements 4a, 4b using a predetermined calculation formula (estimated element temperature calculation formula), but it may also be configured to store a map in the ROM 3b showing the relationship between the detected temperature of the thermistor 5 and the estimated temperature of the energized elements 4a, 4b, and estimate the temperature of the energized elements 4a, 4b based on the map.

[0056] The present invention can also be applied to a case where there are multiple current-carrying circuits, such as when the ECU 2 controls the current-carrying of multiple motors. In this case, when the estimated temperature of one current-carrying element of the multiple systems reaches the current-carrying limit temperature, the current may be limited only for the current-carrying circuit related to the current-carrying element that has reached the current-carrying limit temperature, or the current may be limited for all current-carrying circuits.

[0057] The present invention can be applied not only to the EVP-ECU that controls the electric negative pressure pump that generates the brake negative pressure of the electric vehicle described above, but also to various ECUs that have current-carrying elements through which a large current flows. For example, the present invention can be applied to an ECU that controls power steering, an ECU related to brake control such as an ABS (Anti-lock Brake System), a VSC (Vehicle Stability Control), and an EPB (Electric Parking Brake), and a body ECU that controls the opening and closing of electric doors and the lighting of vehicle lights.

[0058] In addition, in the above embodiment, the thermistor 5 is given as an example of a temperature sensor, but the temperature sensor is not limited to this, and various temperature sensors that are disposed on the control board and can detect the surrounding temperature can be used.

[0059] Furthermore, the present invention can be applied not only to electric vehicles but also to engine vehicles and hybrid vehicles.

[0060] Furthermore, the present invention can be adopted in various vehicle control devices that control actuators such as motors provided in the vehicle. [Explanation of symbols]

[0061] 2: Vehicle control unit (ECU) 3a: CPU (first temperature estimation means, second temperature estimation means, read / write means) 3b:ROM (memory means) 3c:RAM (Memory) 4a, 4b: Current-carrying element 5: Thermistor (temperature sensor)

Claims

[Claim 1] A temperature sensor for detecting an ambient temperature; a first temperature estimating means for estimating a temperature of each of a plurality of current-carrying elements disposed around the single temperature sensor based on an ambient temperature detected by the single temperature sensor; a read / write means for reading and writing the estimated temperatures of the plurality of energization elements estimated by the first temperature estimation means to a memory; a storage means for storing, for each of the plurality of energizing elements, an expected energizing element temperature that is expected in accordance with the ambient temperature detected by the temperature sensor; a second temperature estimating means for starting to estimate the temperatures of the plurality of energizing elements when a predetermined temperature estimation start condition is satisfied after the first temperature estimating means has finished estimating the temperatures; Equipped with The second temperature estimation means When there is no abnormality in reading and writing the memory, the estimation of the temperature of each of the plurality of energizing elements is started based on the estimated temperature at the time of the end of the estimation by the first temperature estimating means, which is written in the memory; A vehicle control device characterized in that, if there is an abnormality in reading and writing to the memory, the predicted temperature of the conductive element corresponding to the ambient temperature detected by the temperature sensor at the start of estimation is read from the memory means, and estimation of the temperature of each of the multiple conductive elements is started based on the read predicted temperature of the conductive element.

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