Sensor device

Abstract

To provide a sensor device capable of continuing at least a partial operation even when a battery voltage is reduced.SOLUTION: A sensor device 1 can continue at least a partial operation since electric power is supplied from a battery 99 in a turn-off period of a start switch 26. A sensor input processing section 30 includes a sensor element 31, an input arithmetic processing circuit 32, and a memory circuit 35. The input arithmetic processing circuit 32 calculates sensor information corresponding to a detection value of the sensor element 31. The memory circuit 35 stores abnormality information including electric power supply failure information. An electric power storage circuit 51 is arranged on a battery power supply line Lb for supplying power of the battery 99 to the sensor input processing section 30 without using the start switch 26, so as to enable a voltage for storing at least data of the memory circuit 35 to be supplied to the sensor input processing section 30 under temporary voltage reduction of the battery 99.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a sensor device.

Background Art

[0002] Conventionally, a rotation angle detection device for detecting the rotation angle of a motor or the like is known. For example, the rotation angle detection device of Patent Document 1 is applied to an electric power steering device and can continue at least part of its operations by the power from a battery during a period when the ignition power supply is turned off.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In Patent Document 1, when the battery voltage drops due to, for example, energization of a large current to a starter at engine startup in a state where the battery life is approaching, there is a risk that the operation of the rotation angle detection device cannot be continued.

[0005] The present invention has been made in view of the above problems, and an object thereof is to provide a sensor device capable of continuing at least part of its operations even when the battery voltage drops.

Means for Solving the Problems

[0006] The sensor device of the present invention can continue at least part of its operations by being supplied with power from a battery (99) during a period when a start switch (26) is turned off, and includes a sensor input processing unit (30, 300) and a voltage holding circuit (51 to 54).

[0007] The sensor input processing unit includes a sensor element (31) that detects changes in physical quantities corresponding to the operation of the object to be detected, an input calculation processing circuit (32) that calculates sensor information according to the detected value of the sensor element, and a storage unit (35) that stores abnormal information including power failure information related to power failure when power is not supplied from the battery while the start switch is off.

[0008] The voltage holding circuit is provided on the battery power supply line that supplies battery voltage to the sensor input processing unit without going through the start switch, and is capable of supplying at least a voltage sufficient to retain data in the storage unit to the sensor input processing unit in the event of a temporary drop in battery voltage. The sensor input processing unit has a power consumption adjustment circuit (38) that, when the voltage of the voltage holding circuit drops, sequentially stops functions other than data holding in the storage unit in accordance with the voltage of the voltage holding circuit. This allows at least some functions to continue even if the battery voltage drops. [Brief explanation of the drawing]

[0009] [Figure 1] This is a schematic diagram of the steering system according to the first embodiment. [Figure 2] This is a block diagram illustrating a sensor device according to the first embodiment. [Figure 3] This is a circuit diagram showing a power storage circuit according to the first embodiment. [Figure 4] This is a time chart showing the voltage during cranking under different battery degradation conditions, based on a reference example. [Figure 5] This is a time chart showing the voltage during cranking in a battery degradation state according to the first embodiment. [Figure 6] This is a flowchart illustrating the power consumption reduction process according to the first embodiment. [Figure 7] This is a flowchart illustrating the power consumption reduction process according to the second embodiment. [Figure 8] This is a flowchart illustrating the power consumption reduction process according to the third embodiment. [Figure 9] This is a circuit diagram showing a power storage circuit according to the fourth embodiment. [Figure 10]It is a time chart showing the voltage during cranking in the battery deterioration state according to the fourth embodiment. [Figure 11] It is a block diagram for explaining the sensor device according to the fifth embodiment. [Figure 12] It is a block diagram for explaining the sensor device according to the sixth embodiment. [Figure 13] It is a block diagram for explaining the sensor device according to the sixth embodiment. [Figure 14] It is a circuit diagram showing the booster circuit according to the sixth embodiment. [Figure 15] It is a circuit diagram showing the booster circuit according to the sixth embodiment. [Figure 16] It is a time chart showing the voltage during cranking in the battery deterioration state according to the sixth embodiment.

Embodiments for Carrying Out the Invention

[0010] Hereinafter, the sensor device according to the present invention will be described based on the drawings. In the following, in a plurality of embodiments, substantially the same configurations are denoted by the same reference numerals and the description thereof is omitted. [[ID=二十七]]

[0011] (First Embodiment) The first embodiment is shown in FIGS. 1 to 5. The sensor device 1 of this embodiment is applied to an electric power steering device 8. FIG. 1 shows the configuration of a steering system 90 including the electric power steering device 8. The steering system 90 includes a steering wheel 91 which is a steering member, a steering shaft 92, a pinion gear 96, a rack shaft 97, wheels 98, and the electric power steering device 8 and the like.

[0012] The steering wheel 91 is connected to the steering shaft 92. A torque sensor 94 for detecting a steering torque is provided on the steering shaft 92. A pinion gear 96 is provided at the tip of the steering shaft 92. The pinion gear 96 meshes with the rack shaft 97. A pair of wheels 98 are connected to both ends of the rack shaft 97 via tie rods or the like.

[0013] When the driver rotates the steering wheel 91, the steering shaft 92 connected to the steering wheel 91 rotates. The rotational motion of the steering shaft 92 is converted into the linear motion of the rack shaft 97 by the pinion gear 96. The pair of wheels 98 are steered at an angle corresponding to the displacement amount of the rack shaft 97.

[0014] The electric power steering device 8 includes a drive device 10 having an ECU 20 and a motor 80, and a reduction gear 89 or the like that is a power transmission unit that decelerates the rotation of the motor 80 and transmits it to the steering shaft 92. That is, the electric power steering device 8 of the present embodiment is a so-called "column assist type", and the steering shaft 92 can be said to be a drive target. It may be a so-called "rack assist type" or the like that transmits the rotation of the motor 80 to the rack shaft 97.

[0015] The motor 80 outputs part or all of the torque required for steering, is driven by being supplied with electric power from a battery 99 (see FIG. 2), and rotates the reduction gear 89 forward and backward. The drive device 10 has an ECU 20 provided on one side in the axial direction of the motor 80 and is a so-called "mechatronic type", but may be a mechatronic separate type in which the motor and the ECU are provided separately. By adopting the mechatronic type, the ECU 20 and the motor 80 can be efficiently arranged in a vehicle with limited mounting space. A sensor device 1 is provided in the ECU 20.

[0016] As shown in Figure 2, the ECU 20 is powered by a battery 99. The battery 99 is shared with another load 79. In this embodiment, the load 79 is described as a starter motor. The ECU 20 is provided with a Bat terminal 21 and an IG terminal 25. Power is supplied to the Bat terminal 21 directly from the battery 99 without going through the vehicle's start switch 26, such as an ignition switch. Power is supplied to the IG terminal 25 from the battery 99 via the start switch 26. Fuses 22 and 27 are provided in the power supply wiring for the Bat terminal 21 and the IG terminal 25, respectively. Hereafter, the start switch will be referred to as "IG" as appropriate.

[0017] The sensor device 1 includes a sensor input processing unit 30, a control unit 40, and a power storage circuit 51, etc. The sensor input processing unit 30 includes a sensor element 31, an input calculation processing circuit 32, an abnormality diagnosis circuit 33, a power failure detection circuit 34, a memory circuit 35, a communication circuit 36, a voltage monitor circuit 37, and a power consumption adjustment circuit 38.

[0018] The sensor device 1 is provided with a sensor Vs power terminal 301 connected to the Bat terminal 21 and a sensor Vcc power terminal 302 connected to the IG terminal 25. In other words, even when the IG is off, the sensor device 1 of this embodiment is configured to receive power from the battery 99 via the sensor Vs power terminal 301, allowing at least some operations, including the counting of the motor 80's rotation count TC, to continue.

[0019] Hereinafter, the voltage generated from the voltage supplied from the Bat terminal 21 and supplied to the sensor Vs power terminal 301 will be referred to as the sensor power supply voltage Vs, and the voltage generated from the voltage supplied from the IG terminal 25 and supplied to the sensor Vcc power terminal 302 will be referred to as the Vcc voltage. Furthermore, the wiring connecting the Bat terminal 21 and the sensor Vs power terminal 301 will be referred to as the battery power supply line Lb, and the wiring connecting the IG terminal 25 and the sensor Vcc power terminal 302 will be referred to as the IG power supply line Lig. A sensor stabilized power supply circuit 61, such as a regulator, is provided on the battery power supply line Lb, and a control stabilized power supply circuit 62 is provided on the IG power supply line Lig.

[0020] The sensor element 31 is, for example, a magnetoresistive element such as an AMR sensor, TMR sensor, or GMR sensor, or a Hall element, which detects the magnetic field of a sensor magnet (not shown) that rotates integrally with the shaft of the motor 80, and outputs the detection signal to the input processing circuit 32. In this embodiment, multiple sensor elements 31 are provided.

[0021] The input processing circuit 32 calculates the motor rotation angle θm and the number of rotations TC of the motor 80 based on the values ​​detected by the sensor element 31. The elements used to calculate the motor rotation angle θm and the elements used to calculate the number of rotations TC may be separate, or the detected values ​​of at least some elements may be shared for the calculation of both the motor rotation angle θm and the number of rotations TC. The calculation results are stored in the memory circuit 35. The number of rotations TC can be calculated, for example, by dividing one rotation of the motor 80 into three or more regions and counting up or down according to the direction of rotation each time the region changes, based on the count value. The number of rotations TC is used to calculate the absolute angle θa, which is the amount of rotation from a reference position that includes multiple rotation information. The absolute angle θa is a value that can be converted to a steering angle using the gear ratio, etc.

[0022] The abnormality diagnosis circuit 33 diagnoses abnormalities in the input arithmetic processing circuit 32, etc. The abnormality diagnosis results are stored in the memory circuit 35. The power failure detection circuit 34 determines a power failure, which is when the power supplied directly from the battery 99 via the sensor Vs power terminal 301 is interrupted.

[0023] The memory circuit 35 stores information to be transmitted to the control unit 40, such as the motor rotation angle θm, rotation count TC, abnormality diagnosis results, and information related to power failure. The memory area for storing each piece of information is configured with 2 bits or more to provide redundancy, enabling abnormality detection by comparison or majority voting. A cyclic redundancy code (CRC), error correction code (ECC), or error detection code (EDC) may also be configured. This improves reliability and makes it applicable to products that require high functional safety.

[0024] The communication circuit 36 ​​transmits the motor rotation angle θm, rotation count TC, abnormality diagnosis result, and information related to power failure to the control unit 40. It also receives various information from the control unit 40. When the IG is turned on, the communication circuit 36 ​​transmits the rotation count TC while the IG is off, the abnormality diagnosis result, and power failure information to the control unit 40 in response to a request signal from the control unit 40. When it receives a recovery signal from the control unit 40, it clears the abnormality diagnosis result and power failure information in the memory circuit 35. If there are multiple memory areas to store the abnormality diagnosis result and power failure information, the judgment result of the abnormality diagnosis circuit 33 and the judgment result of the power failure judgment circuit 34 may be stored simultaneously in multiple memory areas and cleared at different timings. For example, if there are two memory areas, after transmitting power failure information in response to a request signal sent from the control unit 40 when the IG is turned on, one is cleared in response to a recovery signal sent when the control unit 40 receives the power failure information, and the other is cleared in response to a recovery signal sent at an arbitrary timing after cranking is completed, such as in the sequence when the IG is turned off.

[0025] The voltage monitoring circuit 37 monitors the voltage of the battery power supply line Lb. In this embodiment, the charge voltage Vcg between the power storage circuit 51 and the sensor stabilized power supply circuit 61 is monitored, but the sensor power supply voltage Vs or the Bat terminal voltage may be monitored instead of the charge voltage Vcg. The power consumption adjustment circuit 38 adjusts the power consumption within the sensor input processing unit 30 according to the charge voltage Vcg. Details will be described later.

[0026] The control unit 40 is mainly composed of a microcontroller and includes a CPU, ROM, RAM, I / O (not shown), and bus lines connecting these components. Each process in the control unit 40 may be a software process performed by executing a program pre-stored in a physical memory device such as ROM (i.e., a readable non-temporary tangible storage medium) using the CPU, or it may be a hardware process performed by a dedicated electronic circuit.

[0027] The control unit 40 performs various calculations related to the drive control of the motor 80. The control unit 40 also calculates the absolute angle θa using the motor rotation angle θm and the number of rotations TC. In this embodiment, at least one sensor element 31, the input calculation processing circuit 32, and the memory circuit 35 are constantly powered so that the calculation of the number of rotations TC continues even when the IG is off. As a result, even if the motor 80 rotates due to steering the steering wheel 91 while the IG is off, the steering angle θs can be calculated without relearning the reference position. Note that the motor rotation angle θm can be the value used when the IG is on, so continuous power supply for calculation is not necessary.

[0028] Here, as the battery 99 nears the end of its lifespan, if the battery voltage Vbat drops due to the large current flowing to the starter when the engine is started, there is a risk that the sensor input processing unit 30 may become inoperable. If the detection of rotational speed TC is interrupted due to the voltage drop, the steering angle θs will need to be relearned, which will delay the start of control systems such as the electronic stability control (ESC) and autonomous driving that use the steering angle θs.

[0029] Therefore, in this embodiment, even if a voltage drop in the battery 99 occurs due to the driving of a load 79, such as a starter motor, which has a significant impact on the battery voltage Vbat, a power storage circuit 51 is provided so that the sensor input processing unit 30 can be supplied with an operating guarantee voltage for a voltage holding period. Here, the voltage holding period is set according to, for example, the time required for the voltage drop caused by driving the starter to recover.

[0030] As shown in Figure 3, the power storage circuit 51 includes a capacitor 511 and a diode 512. The capacitor 511 is connected to the battery power supply line Lb and to ground. The diode 512 is provided on the battery power supply line Lb such that its anode is on the Bat terminal 21 side and its cathode is on the capacitor 511 side.

[0031] Figures 4 and 5 are time charts showing the voltage during cranking under battery degradation conditions, with the battery voltage Vbat shown as a solid line, the charge voltage Vcg as a dashed line, and the sensor power supply voltage Vs as a dashed line. Figures 10 and others are similar. In the example in Figure 4, when the charge voltage Vcg is sufficiently high, the sensor power supply voltage Vs is adjusted to a set value (e.g., 3.3[V]) by the sensor stabilization power supply circuit 61. Also, when the charge voltage Vcg falls below the set value, the sensor power supply voltage Vs becomes a value corresponding to the charge voltage Vcg.

[0032] As shown in the reference example in Figure 4, if the power storage circuit 51 is not provided, at time x90, if the battery voltage Vbat decreases due to cranking, the sensor power supply voltage Vs will fall below the minimum operating voltage (e.g., 3.0[V]), resulting in a stop period X during which the operation of the sensor input processing unit 30 stops. Similarly, if the capacity of the power storage circuit 51 is insufficient, the operation of the sensor input processing unit 30 may also become impossible.

[0033] As shown in Figure 5, when a power storage circuit 51 is provided, if the battery voltage Vbat decreases due to cranking at time x10, the power stored in the capacitor 511 is supplied to the sensor input processing unit 30. As a result, the decrease in the charge voltage Vcg becomes gradual, and the sensor power supply voltage Vs can be maintained at the set value even during the cranking period. The rate at which the charge voltage Vcg decreases depends on the capacity of the capacitor 511. Therefore, the capacity of the capacitor 511 is set so that a voltage sufficient for the operation of the sensor input processing unit 30 is maintained during the period when the battery voltage Vbat decreases due to cranking. This allows the operation of the sensor input processing unit 30 to continue even if a decrease in battery voltage occurs due to cranking. Note that the battery voltage after cranking is completed will be higher than when the ignition is on due to the generated voltage of the alternator (not shown).

[0034] In this embodiment, the sensor input processing unit 30 is also provided with a power consumption adjustment circuit 38. The power consumption adjustment circuit 38 suppresses power consumption by stopping the power supply for each circuit block based on the charge voltage Vcg detected by the voltage monitor circuit 37. This makes it possible to reduce the capacitance required for the capacitor 511.

[0035] The power consumption suppression process of this embodiment will be explained based on the flowchart in Figure 6. This process is performed at a predetermined interval by the power consumption adjustment circuit 38. Hereafter, the term "step" such as step S101 will be omitted and simply referred to as the symbol "S".

[0036] In S101, the power consumption adjustment circuit 38 determines whether the charge voltage Vcg is 3.0[V] or higher. If it is determined that the charge voltage Vcg is less than 3.0[V] (S101:NO), the process proceeds to S102, and the power failure detection and the write circuit to the memory circuit 35 are stopped. Note that the minimum operating voltage guaranteed for the memory circuit 35 is less than 3.0[V] (for example, 2.0[V]), so new writing to the memory circuit 35 is stopped, but information that has already been written is retained. If it is determined that the charge voltage Vcg is 3.0[V] or higher (S101:YES), the process proceeds to S103, and the power failure detection and the operation of the write circuit to the memory circuit 35 are permitted.

[0037] In S104, the power consumption adjustment circuit 38 determines whether the charge voltage Vcg is 4.3[V] or higher. If it is determined that the charge voltage Vcg is less than 4.3[V] (S104:NO), the process proceeds to S105, and the sensor element 31 and the input calculation processing circuit are stopped. If it is determined that the charge voltage Vcg is 4.3[V] or higher (S104:YES), the process proceeds to S106, and the operation of the sensor element 31 and the input calculation processing circuit 32 is permitted.

[0038] In S107, the power consumption adjustment circuit 38 determines whether the charge voltage Vcg is 5.5[V] or higher. If it is determined that the charge voltage Vcg is less than 5.5[V] (S107: NO), the process proceeds to S108 and the communication circuit 36 ​​is stopped. If it is determined that the charge voltage is 5.5[V] or higher (S107: YES), the process proceeds to S109 and the operation of the communication circuit 36 ​​is permitted.

[0039] In S110, the power consumption adjustment circuit 38 determines whether the charge voltage Vcg is 8.0[V] or higher. If it is determined that the charge voltage Vcg is less than 8.0[V] (S110: NO), the process proceeds to S111 and the abnormal diagnosis circuit 33 is stopped. If it is determined that the charge voltage Vcg is 8.0[V] or higher (S110: YES), the process proceeds to S112 and the operation of the abnormal diagnosis circuit 33 is permitted.

[0040] In this embodiment, the minimum operating voltage for each function is determined based on its functionality, and the operation is stopped according to the charge voltage Vcg. The judgment thresholds S101, S104, S107, and S110 in Figure 6 correspond to the minimum operating voltage for each function. The judgment thresholds shown here are just examples and can be set arbitrarily. Also, the order in which functions are stopped may differ depending on the application being used, as the priority will vary. The same applies to the judgment thresholds in the power consumption reduction process according to the embodiment described later.

[0041] As described above, the sensor device 1 of this embodiment is able to continue at least some operations by being powered from the battery 99 during the period when the start switch 26 is off, and comprises a sensor input processing unit 30 and a power storage circuit 51.

[0042] The sensor input processing unit 30 includes a sensor element 31, an input calculation processing circuit 32, and a memory circuit 35. The sensor element 31 detects changes in physical quantities corresponding to the operation of the motor 80. The input calculation processing circuit 32 calculates the motor rotation angle θm and the number of rotations TC as sensor information according to the value detected by the sensor element 31. The memory circuit 35 stores abnormal information, including power failure information related to power failure when power is not supplied from the battery 99 while the start switch 26 is off, and the sensor input calculation processing results.

[0043] The power storage circuit 51 is provided on the battery power supply line Lb, which supplies power from the battery 99 to the sensor input processing unit 30 without going through the start switch 26, and is capable of supplying the sensor input processing unit 30 with a voltage sufficient to retain data in the memory circuit 35 during a temporary voltage drop in the battery 99. Specifically, by providing the power storage circuit 51, even if the voltage of the battery 99 drops, it is possible to retain a voltage sufficient to retain data in the memory circuit 35 for a voltage retention period set according to the cranking period. As a result, even if the battery voltage Vbat temporarily drops due to cranking or the like, the sensor processing circuit results, abnormality diagnosis results, and power loss information during IG off can be retained.

[0044] The power storage circuit 51 has a capacitor 511 connected to the battery power supply line Lb. When the battery voltage Vbat drops, the power stored in the capacitor 511 can be used to maintain the sensor power supply voltage Vs appropriately.

[0045] The sensor input processing unit 30 has a power consumption adjustment circuit 38 that sequentially stops functions other than data retention in the memory circuit 35 in accordance with the charge voltage Vcg, which is the voltage of the power storage circuit 51, when the charge voltage Vcg decreases. This extends the time for which the sensor power supply voltage Vs can be maintained at or above the operating guarantee voltage. In addition, the capacity of the power storage circuit 51 (specifically the capacitor 511) can be reduced.

[0046] (Second Embodiment) The second embodiment will be described with reference to Figure 7. The second and third embodiments differ from the above embodiments in their power consumption reduction processing, so this point will be explained in detail.

[0047] The power consumption suppression process of this embodiment will be explained based on the flowchart in Figure 7. The processes in S121 to S125 are the same as the processes in S101 to S105 in Figure 6. If it is determined in S124 that the charge voltage Vcg is 4.3[V] or higher (S124:YES), the process proceeds to S126.

[0048] In S126, the power consumption adjustment circuit 38 determines whether the charge voltage Vcg is 5.5[V] or higher. If it is determined that the charge voltage Vcg is less than 5.5[V] (S126:NO), the process proceeds to S127. If it is determined that the charge voltage Vcg is 5.5[V] or higher (S126:YES), the process proceeds to S129.

[0049] In S127, which is triggered when the charge voltage Vcg is 4.3[V] or higher and less than 5.5[V], the power consumption adjustment circuit 38 sets the sensor element 31 and the input calculation processing circuit 32 to intermittent operation. Intermittent operation means, for example, designing a circuit that normally operates in 100μs to operate in 1ms. In S128, which is triggered when the charge voltage Vcg is less than 5.5[V], the power consumption adjustment circuit 38 stops the communication circuit 36.

[0050] In S129, which is initiated when it is determined that the charge voltage Vcg is 5.5[V] or higher (S126:YES), the operation of the communication circuit 36 ​​is permitted, and the sensor element 31 and the input calculation processing circuit 32 are set to normal operation (operation at 100μs in the example above). The processing in S130 to S132 is the same as the processing in S110 to S112 in Figure 6.

[0051] In this embodiment, the sensor element 31 and the input processing circuit 32, which have relatively high power consumption, are operated intermittently within a predetermined voltage range (in this embodiment, 4.3[V] or more and less than 5.5[V]) above the minimum detection operating voltage that stops the operation of the sensor element 31 and the input processing circuit 32. By reducing the operating frequency of the sensor element 31 and the input processing circuit 32, power consumption when the battery voltage drops can be further suppressed. This also provides the same effects as in the above embodiment.

[0052] (Third embodiment) A third embodiment will be described with reference to Figure 8. In this embodiment, instead of the charge voltage Vcg, the sensor power supply voltage Vs is monitored and power consumption suppression processing is performed. In this embodiment, the sensor power supply voltage Vs is adjusted to 3.3[V] or less, so the minimum operating voltage is set within this range.

[0053] The power consumption reduction process based on the sensor power supply voltage Vs will be explained using the flowchart in Figure 8. In S151, the power consumption adjustment circuit 38 determines whether the sensor power supply voltage Vs is 2.0[V] or higher. If it is determined that the sensor power supply voltage Vs is less than 2.0[V] (S151:NO), the process proceeds to S152. If it is determined that the sensor power supply voltage Vs is 2.0[V] or higher (S151:YES), the process proceeds to S153. The processes in S152 and S153 are the same as those in S102 and S103 in Figure 6.

[0054] In S154, the power consumption adjustment circuit 38 determines whether the sensor power supply voltage Vs is 2.5[V] or higher. If it is determined that the sensor power supply voltage is less than 2.5[V] (S154:NO), the process proceeds to S155. If it is determined that the sensor power supply voltage Vs is 2.5[V] or higher (S154:YES), the process proceeds to S156. The processes in S155 and S156 are the same as those in S105 and S106 in Figure 6.

[0055] In S157, the power consumption adjustment circuit 38 determines whether the sensor power supply voltage Vs is 3.0[V] or higher. If it is determined that the sensor power supply voltage Vs is less than 3.0[V] (S157:NO), the process proceeds to S158, and the communication circuit 36 ​​and the abnormal diagnosis circuit 33 are stopped. If it is determined that the sensor power supply voltage Vs is 3.0[V] or higher (S157:YES), the process proceeds to S159, and the operation of the communication circuit 36 ​​and the abnormal diagnosis circuit 33 is permitted.

[0056] In this embodiment, instead of monitoring the charge voltage Vcg, the sensor power supply voltage Vs is monitored, and the power consumption adjustment circuit 38 sequentially stops functions in the memory circuit 35 other than data retention according to the sensor power supply voltage Vs. This configuration also produces the same effects as the above embodiment.

[0057] (Fourth Embodiment) A fourth embodiment is shown in Figures 9 and 10. In this embodiment, the power storage circuit differs from that of the above embodiment, so this point will be explained in detail. As shown in Figure 9, the power storage circuit 52 of this embodiment includes a secondary battery 521, a charging control circuit 522, and diodes 523 and 524. The charging control circuit 522 is provided to prevent overcharging of the secondary battery 521, and may be, for example, a resistor.

[0058] Diodes 523 and 524 are both positioned so that their anode faces the battery and their cathode faces the sensor power supply. Diode 523 is positioned between the Bat terminal 21 and the secondary battery 521, and diode 524 is positioned between the secondary battery 521 and the sensor stabilized power supply circuit 61.

[0059] When the battery voltage Vbat is sufficiently high, power is supplied to the sensor input processing unit 30 via the wiring La connecting the cathodes of diodes 523 and 524. On the other hand, when the battery voltage Vbat decreases, power from the secondary battery 521 is supplied to the sensor input processing unit 30 via diode 524.

[0060] As shown in Figure 10, when the battery voltage Vbat decreases due to cranking at time x20, power stored in the secondary battery 521 is supplied to the sensor input processing unit 30. The capacity of the secondary battery 521 is set to maintain a voltage sufficient for the operation of the sensor input processing unit 30 during the period when the battery voltage Vbat decreases due to cranking, similar to the capacitor 511. In the example in Figure 10, the charge voltage Vcg is maintained by the voltage of the secondary battery 521 until time x21, and then gradually decreases. The sensor power supply voltage Vs is maintained at the set value by the power from the secondary battery 521 even during the cranking period.

[0061] In this embodiment, the power storage circuit 52 has a secondary battery 521 connected to the battery power supply line Lb. This allows the sensor power supply voltage Vs to be appropriately maintained by using the power of the secondary battery 521 when the battery voltage Vbat decreases. It also provides the same effects as in the above embodiment.

[0062] (Fifth embodiment) A fifth embodiment is shown in Figure 11. The sensor input processing unit 300 in this embodiment differs from the above embodiment in that the voltage monitor circuit 37 is omitted. In Figure 6, the power storage circuit 51 of the first embodiment is provided, but the power storage circuit 52 of the fourth embodiment may also be used. In this embodiment, the charge voltage Vcg is monitored by the control unit 40. Furthermore, the calculations related to the power consumption suppression process shown in Figure 6 are performed by the control unit 40, and the power consumption adjustment circuit 38 is operated by a command from the control unit 40. This simplifies the configuration of the sensor input processing unit 300 and provides the same effects as the above embodiment.

[0063] (Sixth Embodiment) A sixth embodiment is shown in Figures 12 to 16. As shown in Figures 12 and 13, the sensor device 2 differs from the above embodiment in that a boost circuit 53 is provided instead of a power storage circuit. As shown in Figure 12, a voltage monitor circuit 37 for monitoring the boosted voltage Vbu may be provided on the sensor input processing unit 30 side, or as shown in Figure 13, the boosted voltage Vbu may be monitored in the control unit 40.

[0064] As shown in Figure 14, the boost circuit 53 can be a flyback circuit. The boost circuit 53 includes a switching element 531, an inductor 532, a diode 533, a capacitor 534, and a boost control circuit 535. By controlling the on / off operation of the switching element 531, the boosted voltage Vbu can be applied to the sensor input processing unit 30.

[0065] Alternatively, the boost circuit 53 may be replaced with a boost circuit 54 with a charge pump configuration as shown in Figure 15. The boost circuit 54 has switch circuit sections 541-543 consisting of two switches and a capacitor, a diode 544, a capacitor 545, and a boost control circuit 546. By switching the on / off state of the switch circuit sections 541-543, the boosted voltage Vbu can be applied to the sensor input processing unit 30. Figure 15 shows an example in which three switch circuit sections 541-543 are provided, but the number of switch circuits can be any number.

[0066] When the voltage of the battery 99 drops due to the driving of a load 79 such as a motor that consumes a large amount of power, like a starter, the battery voltage Vbat does not actually drop to 0[V], but rather a voltage of about 2[V] remains. Therefore, in this embodiment, the remaining power of the battery 99 is utilized by providing boost circuits 53 and 54. Here, the type of boost circuit may be other than those shown for boost circuits 53 and 54.

[0067] As shown in Figure 16, at time x30, the battery voltage Vbat decreases due to cranking. Even if the battery voltage Vbat drops to about 2[V], the sensor power supply voltage Vs can be maintained at the set value by driving the boost circuits 53 and 54. This allows the sensor input processing unit 30 to continue operating.

[0068] In this embodiment, boost circuits 53 and 54 are provided on the battery power supply line Lb as a voltage holding circuit. This allows the sensor power supply voltage Vs to be properly maintained even when the battery voltage Vbat decreases. It also provides the same effects as in the above embodiment.

[0069] In this embodiment, the memory circuit 35 corresponds to the "storage unit," the power storage circuits 51 and 52 and the boost circuits 53 and 54 correspond to the "voltage holding circuits," and the motor 80 corresponds to the "detection target." The motor rotation angle θm and the number of rotations TC of the motor 80 correspond to the "sensor information."

[0070] (Other embodiments) In the above embodiment, the stabilized power supply circuit for the sensor is provided outside the sensor input processing unit. In other embodiments, the stabilized power supply circuit for the sensor may be provided inside the sensor input processing unit. The boost circuit in the fourth embodiment is similar. Furthermore, in the sensor input processing unit, miniaturization is possible by integrating components other than inductors and capacitors, which are difficult to integrate into ICs, into a single IC and packaging it into one package.

[0071] In the above embodiment, the charge voltage or boost voltage is monitored by a voltage monitoring circuit or control unit, and power consumption reduction processing is performed by a power consumption adjustment circuit according to the voltage. In other embodiments, the power consumption adjustment circuit may be omitted, especially when a boost circuit is provided, and power consumption reduction processing according to the voltage may not be performed.

[0072] In the above embodiment, the sensor device detects the rotation of the motor. In other embodiments, the sensor device may be something other than a motor rotation angle sensor, such as a torque sensor or a steering sensor. In the above embodiment, one control unit is provided for one sensor input processing circuit. In other embodiments, multiple control units may be provided for one sensor input processing circuit, or multiple sensor input processing circuits may be provided for one control unit.

[0073] In the above embodiment, the motor is a three-phase brushless motor. In other embodiments, the motor unit is not limited to a three-phase brushless motor, but can be any type of motor. Furthermore, the motor unit is not limited to a motor (electric motor), but can be a generator, or a so-called motor-generator that combines the functions of both an electric motor and a generator. In the above embodiment, the sensor device is applied to an electric power steering system. In other embodiments, the sensor device may be applied to a device other than an electric power steering system.

[0074] The control unit and its method described herein may be implemented by a dedicated computer provided by configuring a processor and memory programmed to perform one or more functions embodied by a computer program. Alternatively, the control unit and its method described herein may be implemented by a dedicated computer provided by configuring a processor by one or more dedicated hardware logic circuits. Alternatively, the control unit and its method described herein may be implemented by one or more dedicated computers configured by a combination of a processor and memory programmed to perform one or more functions and a processor configured by one or more hardware logic circuits. Furthermore, the computer program may be stored as instructions executed by the computer on a computer-readable non-transitional tangible recording medium. The present invention is not limited in any way to the embodiments described above, and can be implemented in various forms without departing from the spirit of the invention. [Explanation of symbols]

[0075] 1, 2... Sensor device 26. Start switch 30, 300... Sensor Input Processing Unit 31...Sensor element 32...Input processing circuit 35. Memory circuit (storage unit) 51, 52... Power storage circuit (voltage holding circuit) 511...Capacitor 521...Rechargeable battery 53, 54... Boost circuit (voltage holding circuit) 99... Battery

Claims

1. A sensor device that can continue at least some of its operations by being powered from a battery (99) during the period when the start switch (26) is turned off, A sensor input processing unit (30, 300) having a sensor element (31) that detects changes in physical quantities in accordance with the operation of the object to be detected (80), an input calculation processing circuit (32) that calculates sensor information according to the detected value of the sensor element, and a storage unit (35) that stores abnormal information including power loss information related to power loss when power is not supplied from the battery while the start switch is off, A voltage holding circuit (51-54) is provided on the battery power supply line that supplies power from the battery to the sensor input processing unit without going through the start switch, and is capable of supplying the sensor input processing unit with a voltage sufficient to hold the data in the storage unit when the battery voltage temporarily drops. Equipped with, The sensor input processing unit is a sensor device having a power consumption adjustment circuit (38) that sequentially stops functions other than data retention in the storage unit in accordance with the voltage of the voltage holding circuit when the voltage of the voltage holding circuit drops.

2. The sensor device according to claim 1, wherein the voltage holding circuit (51) has a capacitor (511) connected to the battery power supply line.

3. The sensor device according to claim 1, wherein the voltage holding circuit (52) has a secondary battery (521) connected to the battery power supply line.

4. The sensor device according to claim 1, wherein the voltage holding circuits (53, 54) are boost circuits provided on the battery power supply line.

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