JP6488930B2 - Electronic control unit - Google Patents

Description

  The present invention relates to an electronic control device that controls an inductive load.

  As this type of electronic control device, there is an electronic control device described in Patent Document 1. The electronic control device described in Patent Literature 1 controls turning on and off of the indicator lamp. Specifically, the indicator lamp is electrically connected to a vehicle-mounted DC power source via an ignition switch. A transistor is disposed on the ground line of the indicator lamp. The electronic control device described in Patent Document 1 turns on the display lamp by turning on the transistor and turns off the display lamp by turning off the transistor. When the ground line of the indicator lamp is the first ground line, the electronic control unit is electrically connected to a second ground line different from the first ground line.

JP-A-8-19167

  By the way, in the electronic control device described in Patent Document 1, when the first ground line is disconnected due to some factor, the current path of the indicator lamp is lost, and thus the indicator lamp may not be lit.

  On the other hand, as a countermeasure, a method in which the first ground line is divided into two systems is also conceivable. That is, if the first ground line is divided into two systems, even if one of the ground lines is disconnected, the current path of the indicator lamp can be secured by the other ground line, so the indicator lamp can be turned on. is there. However, there are cases where it is difficult to make the first grounding line into two systems due to cost reduction, reduction of the vehicle body weight, etc., and it is necessary to take some measures on the electronic control device side.

  In addition, such a subject is a subject common to the electronic control apparatus which controls not only the electronic control apparatus which controls lighting and extinction of an indicator lamp but inductive load.

  The present invention has been made in view of such circumstances, and an object thereof is to provide an electronic control device that can ensure driving of an inductive load even when the ground line of the inductive load is disconnected. is there.

In order to solve the above problems, an electronic control device (4) for controlling an inductive load (Lu, Lv, Lw) includes a connection terminal (Tu, Tv, Tw), a first ground terminal (Tgnd1), a low side A switching element (420u, 420v, 420w), a control unit (40), a second ground terminal (Tgnd2), a connection line (L23), and a connection switching element (430) are provided. The connection terminal is electrically connected to the inductive load. The first ground terminal is electrically connected to the connection terminal via a first internal ground line (L21) provided inside the electronic control device, and a first external ground line (external to the electronic control device). L11) is electrically connected to ground. The low side switching element is disposed on the first internal ground line. The control unit turns on and off the low-side switching element. The second ground terminal is electrically connected to the control unit via a second internal ground line (L22) different from the first internal ground line, and is a second external ground different from the first external ground line. Electrically connected to ground through a line. The connection line connects the first internal ground line and the second internal ground line. The connecting switching element is a MOSFET. The drain terminal of the MOSFET is electrically connected to the first internal ground line. The source terminal of the MOSFET is electrically connected to the second internal ground line. When the first external ground line is not disconnected, the ground potential is applied to the gate terminal of the MOSFET, so that the MOSFET is turned off. When the first external ground line is disconnected, a voltage capable of turning on the MOSFET is applied to the gate terminal of the MOSFET, so that the MOSFET is turned on.

  According to this configuration, when the first external ground line that is the ground line of the inductive load is disconnected, the connection switching element is turned on, whereby the first internal ground line and the second internal ground line are electrically connected. Connected to. Thereby, since the inductive load is electrically connected to the ground via the second internal ground line, a current can flow through the inductive load. Therefore, driving of the inductive load can be ensured.

  In addition, the code | symbol in the bracket | parenthesis as described in the said means and a claim is an example which shows a corresponding relationship with the specific means as described in embodiment mentioned later.

  According to the present invention, driving of the inductive load can be ensured even when the ground line of the inductive load is disconnected.

1 is a block diagram showing a schematic configuration of a vehicle shift-by-wire system. It is a block diagram which shows the structure of 1st Embodiment of an electronic control apparatus. FIGS. 4A to 4C are timing charts showing transitions of the state of the MOSFET of the ground switching unit, the gate-source voltage of the MOSFET, and the applied voltage of the first ground terminal in the electronic control device of the first embodiment. It is. It is a block diagram which shows the structure of 2nd Embodiment of an electronic controller. It is a flowchart which shows the procedure of the process performed by the electronic control apparatus of 2nd Embodiment. (A) to (D) are the states of the MOSFET of the ground switching unit, the gate-source voltage of the MOSFET, the applied voltage of the first ground terminal, and the output signal of the comparator in the electronic control device of the second embodiment. It is a timing chart which shows transition.

<First Embodiment>
Hereinafter, a first embodiment of the electronic control device will be described. The electronic control device of this embodiment is used in a vehicle shift-by-wire system. First, an outline of the shift-by-wire system will be described.

  As shown in FIG. 1, the shift-by-wire system 1 includes a shift operation unit 2, a shift sensor 3, an electronic control unit (Electronic Control Unit) 4, a motor 5, and an encoder 6. Hereinafter, the electronic control unit 4 is abbreviated as “ECU 4”.

  The shift operation unit 2 is operated by the user when switching the shift range of the automatic transmission 7 of the vehicle. As the shift range of the automatic transmission 7, for example, a “P (parking) range”, an “R (reverse) range”, an “N (neutral) range”, a “D (drive) range”, and the like are provided. The operation position of the shift operation unit 2 is set to one of a plurality of shift ranges.

  The shift sensor 3 detects a shift position that is an operation position of the shift operation unit 2. The shift sensor 3 outputs information on the detected shift position to the ECU 4.

  The motor 5 is a three-phase AC motor. The motor 5 switches the shift range of the automatic transmission 7 by driving the automatic transmission 7 based on an instruction from the ECU 4.

  The encoder 6 detects the rotational position of the motor 5. The encoder 6 outputs information on the detected rotational position of the motor 5 to the ECU 4.

  The ECU 4 switches the shift range of the automatic transmission 7 by controlling the drive of the motor 5 based on the output signals of the shift sensor 3 and the encoder 6.

Next, the configuration of the ECU 4 for driving the motor 5 will be described in detail.
As shown in FIG. 2, the ECU 4 includes first to third connection terminals Tu, Tv, Tw, and first and second ground terminals Tgnd1, Tgnd2 as external connection terminals.

  The first to third connection terminals Tu, Tv, Tw are electrically connected to one end portions of the phase coils Lu, Lv, Lw of the motor 5, respectively. A battery voltage VB is applied from the vehicle battery (not shown) to the other end of each phase coil Lu, Lv, Lw. In the present embodiment, each phase coil Lu, Lv, Lw corresponds to an inductive load.

  The first ground terminal Tgnd1 is electrically connected to the ground via a first external ground line L11 provided outside the ECU 4. Thereby, the ground potential is applied to the first ground terminal Tgnd1. The ground is, for example, a vehicle body. Inside the ECU 4, a first internal ground line L21 that is electrically connected to the first ground terminal Tgnd1 is provided.

  The second ground terminal Tgnd2 is electrically connected to the ground via a second external ground line L12 different from the first external ground line L11. Thereby, the ground potential is applied to the second ground terminal Tgnd2. A second internal ground line L22 that is electrically connected to the second ground terminal Tgnd2 is provided inside the ECU 4.

  The ECU 4 includes a microcomputer 40, a pre-driver 41, a drive circuit 42, and a ground switching unit 43. Hereinafter, the microcomputer 40 is abbreviated as “microcomputer 40”. In the present embodiment, the microcomputer 40 corresponds to a control unit.

  The drive circuit 42 is a circuit for driving the motor 5. The drive circuit 42 includes three MOSFETs (MOS field effect transistors) 420u, 420v, and 420w. In the present embodiment, the MOSFETs 420u, 420v, 420w correspond to low-side switching elements. The drain terminals of the MOSFETs 420u, 420v, 420w are electrically connected to the first to third connection terminals Tu, Tv, Tw, respectively. The source terminals of the MOSFETs 420u, 420v, 420w are electrically connected to the first ground terminal Tgnd1 via the first internal ground line L21. That is, when the MOSFETs 420u, 420v, and 420w are turned on, the phase coils Lu, Lv, and Lw are electrically connected to the ground via the first ground terminal Tgnd1, so that the loads on the phase coils Lu, Lv, and Lw are loaded. Currents Iu, Iv, and Iw flow. Further, when the MOSFETs 420u, 420v, 420w are turned off, the load currents Iu, Iv, Iw do not flow through the phase coils Lu, Lv, Lw. The motor 5 is driven by controlling the load currents Iu, Iv, and Iw flowing through the phase coils Lu, Lv, and Lw through turning on and off the MOSFETs 420u, 420v, and 420w.

  The pre-driver 41 turns on and off the MOSFETs 420u, 420v, and 420w by outputting gate signals to the respective gate terminals of the MOSFETs 420u, 420v, and 420w. Specifically, the pre-driver 41 turns on the MOSFETs 420u, 420v, and 420w by applying a predetermined gate voltage to the gate terminals of the MOSFETs 420u, 420v, and 420w. The pre-driver 41 also turns off the MOSFETs 420u, 420v, 420w by stopping the application of voltages to the respective gate terminals of the MOSFETs 420u, 420v, 420w. The pre-driver 41 is electrically connected to the second ground terminal Tgnd2 via the second internal ground line L22.

  The microcomputer 40 is electrically connected to the second ground terminal Tgnd2 via the second internal ground line L22. The microcomputer 40 detects the rotational position of the motor 5 based on the output signal of the encoder 6 and recognizes the actual shift range of the automatic transmission 7 based on the detected rotational position of the motor 5. Further, the microcomputer 40 detects which shift position of the shift operation unit 2 is operated based on the output signal of the shift sensor 3. The microcomputer 40 sets the target shift range of the automatic transmission 7 based on the detected shift position, and drives the motor 5 so that the actual shift range of the automatic transmission 7 becomes the target shift range. Specifically, the microcomputer 40 transmits a drive signal to the pre-driver 41. As a result, a gate signal corresponding to the drive signal is applied from the pre-driver 41 to the respective gate terminals of the MOSFETs 420u, 420v, 420w, and the MOSFETs 420u, 420v, 420w are turned on / off. The drive of the motor 5 is controlled by changing the load currents Iu, Iv, Iw flowing through the phase coils Lu, Lv, Lw by turning on / off the MOSFETs 420u, 420v, 420w.

  When the first external ground line L11 is not disconnected, the ground switching unit 43 disconnects the electrical connection between the first internal ground line L21 and the second internal ground line L22, and the first external ground line L11 is disconnected. Sometimes the first internal ground line L21 and the second internal ground line L22 are electrically connected. The ground switching unit 43 includes a connection line L23 and a MOSFET 430.

  The connection line L23 connects the first internal ground line L21 and the second internal ground line L22.

  MOSFET 430 is arranged in connection line L23. In the present embodiment, the MOSFET 430 corresponds to a connection switching element. The drain terminal of the MOSFET 430 is electrically connected to the first ground terminal Tgnd1 via the first internal ground line L21. The source terminal of the MOSFET 430 is electrically connected to the second ground terminal Tgnd2 via the second internal ground line L22. A resistor R is disposed between the gate terminal and the source terminal of the MOSFET 430. Further, the gate terminal of the MOSFET 430 is electrically connected to the first internal ground line L21 via the Zener diode ZD and the diode D to which the anode terminals are connected. The cathode terminal of the Zener diode ZD is electrically connected to the first internal ground line L21. The cathode terminal of the diode D is electrically connected to the gate terminal of the MOSFET 430. The Zener voltage Vz of the Zener diode ZD is set to a value at which the Zener diode ZD is energized when the voltage applied to the first ground terminal Tgnd1 becomes larger than the ground potential.

Next, an operation example of the ECU 4 of this embodiment will be described.
When the first ground terminal Tgnd1 is normally connected to the ground via the first external ground line L11 and the first ground terminal Tgnd1 is also normally connected to the ground via the second external ground line L12, a Zener diode A ground potential is applied between both ends of ZD. That is, since no potential difference is generated between the terminals of the Zener diode ZD, no current flows through the Zener diode ZD. Therefore, the gate voltage of MOSFET 430 is maintained at the ground potential, and MOSFET 430 is maintained in the off state. That is, the electrical connection between the first internal ground line L21 and the second internal ground line L22 is interrupted.

  When the first external ground line L11 is disconnected for some reason, the battery voltage VB is applied to the first ground terminal Tgnd1 when any of the MOSFETs 420u, 420v, 420w is turned on. As a result, as shown in FIG. 3C, when the voltage of the first ground terminal Tgnd1 rises to the predetermined voltage Va at time t1, as shown in FIG. 3B, the voltage between the gate and the source of the MOSFET 430 is increased. A gate threshold voltage VGSth is applied. The predetermined voltage Va is a value obtained by adding the Zener voltage Vz and the gate threshold voltage VGSth. The gate threshold voltage VGSth is a gate-source voltage necessary for turning on the MOSFET 430. When the gate threshold voltage VGSth is applied between the gate and the source of the MOSFET 430, the MOSFET 430 is switched from the OFF state to the ON state as shown in FIG. As a result, the first internal ground line L21 and the second internal ground line L22 become conductive, so that the phase coils Lu, Lv, Lw are electrically connected to the ground via the second internal ground line L22.

  According to ECU4 of this embodiment demonstrated above, the effect | action and effect shown by the following (1)-(3) can be acquired.

  (1) When the first external ground line L11 is disconnected, each phase coil Lu, Lv, Lw is electrically connected to the ground via the second internal ground line L22 by the ground switching unit 43. Load currents Iu, Iv, and Iw can be supplied to Lu, Lv, and Lw, respectively. Therefore, the motor 5 can be driven.

  (2) When the first external ground line L11 is disconnected, the load current Iu, Iv, Iw that has lost its place may flow to the pre-driver 41, various elements in the ECU 4, or the like, which may damage the ECU 4. is there. In this regard, in the ECU 4 of the present embodiment, when the first external ground line L11 is disconnected, the load currents Iu, Iv, and Iw are reduced by connecting the first internal ground line L21 and the second internal ground line L22. It can flow to the ground via the second internal ground line L22. Therefore, damage to the ECU 4 can be avoided.

  (3) The ground switching unit 43 is configured as shown in FIG. Thus, when the first external ground line L11 is not disconnected, the electrical connection between the first internal ground line L21 and the second internal ground line L22 is interrupted, and when the first external ground line L11 is disconnected. A configuration in which the first internal ground line L21 and the second internal ground line L22 are electrically connected can be easily realized.

Second Embodiment
Next, a second embodiment of the ECU 4 will be described. Hereinafter, the difference from the first embodiment will be mainly described.

  As shown in FIG. 4, the ECU 4 of the present embodiment has a function of turning on and off a warning light 8 provided on, for example, an instrument panel of a vehicle. The warning lamp 8 is turned on to notify the driver of the abnormality.

  The ECU 4 further includes a comparator 44. The gate voltage of the MOSFET 430 is applied to the non-inverting input terminal of the comparator 44. A predetermined threshold voltage Vth is applied to the inverting input terminal of the comparator 44. That is, the comparator 44 outputs a logically low level signal when the gate voltage of the MOSFET 430 is less than the threshold voltage Vth, and logically high level when the gate voltage of the MOSFET 430 is equal to or higher than the threshold voltage Vth. The signal is output. The output signal of the comparator 44 is taken into the microcomputer 40. The threshold voltage Vth is set to a value larger than the ground potential.

  The microcomputer 40 repeatedly executes the process shown in FIG. 5 at a predetermined cycle based on the output signal of the comparator 44. As shown in FIG. 5, the microcomputer 40 first determines whether or not the output signal of the comparator 44 is at a high level (step S1). When the output signal of the comparator 44 is at the low level (step S1: NO), the microcomputer 40 determines that the first external ground line L11 is not disconnected, and ends the series of processes.

  If the output signal of the comparator 44 is at a high level (step S1: YES), the microcomputer 40 determines that the first external ground line L11 is disconnected, and applies the predetermined voltage Vga to the gate terminal of the MOSFET 430 (step S1). S2). The predetermined voltage Vga is equal to or higher than the gate threshold voltage VGSth, and is set to a value that can maintain the MOSFET 430 in the on state. Following the process of step S2, the microcomputer 40 turns on the warning lamp 8 (step S3), and then executes fail-safe control (step S4). Fail safe control is vehicle control for safely stopping the vehicle, for example, by limiting the speed of the vehicle. The microcomputer 40 determines whether or not the vehicle has safely stopped following the process of step S4 (step S5). For example, the microcomputer 40 determines that the vehicle has safely stopped when the vehicle is stopped and the shift range of the automatic transmission 7 is set to the P range. When the microcomputer 40 determines that the vehicle has been safely stopped (step S5: YES), the microcomputer 40 stops applying the voltage to the gate terminal of the MOSFET 430 (step S6).

Next, the operation of the ECU 4 of this embodiment will be described.
As shown in FIG. 6B, when the gate-source voltage of the MOSFET 430 reaches the gate threshold voltage VGSth at time t1 due to the disconnection of the first external ground line L11, the gate voltage of the MOSFET 430 becomes the threshold voltage Vth of the comparator 44. That's it. Therefore, as shown in FIG. 6D, the output signal of the comparator 44 is switched from the low level to the high level at time t1. Therefore, when the microcomputer 40 subsequently executes the processing shown in FIG. 5 at time t2, the microcomputer 40 applies the predetermined voltage Vga to the gate terminal of the MOSFET 430, so that the MOSFET 430 is maintained in the ON state. In addition, by applying the predetermined voltage Vga to the gate terminal of the MOSFET 430, the applied voltage of the first ground terminal Tgnd1 decreases from the predetermined voltage Va to the drain-source on-voltage Von of the MOSFET 430, as shown in FIG. 6C. To do. That is, the voltage applied to the first ground terminal Tgnd1 is lowered to a value substantially equal to the ground potential. The drain-source on-voltage Von indicates a potential difference between the drain and source of the MOSFET 430 when the MOSFET 430 is in the on state. Thereby, the low potential side of each phase coil Lu, Lv, Lw can be brought close to the potential in a state where the first external ground line L11 is not disconnected.

  According to ECU4 of this embodiment demonstrated above, the effect | action and effect shown by the following (4) and (5) can further be acquired.

  (4) When the first external ground line L11 is disconnected, the microcomputer 40 applies the predetermined voltage Vga to the gate terminal of the MOSFET 430, so that the MOSFET 430 can be kept on. Further, the voltage applied to the first ground terminal Tgnd1 can be brought close to a voltage substantially equal to the ground potential. That is, the low potential side of each phase coil Lu, Lv, Lw can be brought close to the ground potential. Thereby, since the motor 5 can be driven substantially in the same manner as in the situation where the first external ground line L11 is not disconnected, the shift range of the automatic transmission 7 can be switched more appropriately. Therefore, the vehicle can be safely stopped more reliably by the driver.

  (5) The microcomputer 40 detects the disconnection of the first external ground line L11 based on the output signal of the comparator 44, in other words, based on the gate voltage of the MOSFET 430. Thereby, the disconnection of the first external ground line L11 can be easily detected.

<Other embodiments>
In addition, each embodiment can also be implemented with the following forms.
The configuration of the ground switching unit 43 can be changed as appropriate. For example, instead of the MOSFET 430, a bipolar transistor, an integrated (IC) transistor, or the like may be used. The microcomputer 40 may switch the MOSFET 430 from the off state to the on state. Specifically, the microcomputer 40 may directly monitor the voltage of the first ground terminal Tgnd1 and turn on the MOSFET 430 when the voltage of the first ground terminal Tgnd1 becomes equal to or higher than a predetermined voltage. According to such a configuration, the Zener diode ZD and the diode D can be eliminated from the ground switching unit 43. In short, the ground switching unit 43 cuts off the electrical connection between the first internal ground line L21 and the second internal ground line L22 when the first external ground line L11 is not disconnected, and the first external ground line L11. What is necessary is just to electrically connect the first internal ground line L21 and the second internal ground line L22 when is disconnected.

  The ECU 4 is not limited to each phase coil Lu, Lv, Lw of the motor 5 and may be any one that controls one or more arbitrary inductive loads.

  The application target of the ECU 4 is not limited to the ECU of the shift-by-wire system 1 of the vehicle, but may be an engine ECU or an ECU of an automatic transmission, for example. For example, when the ECU 4 is used as an engine ECU, the engine output may be limited as fail-safe control.

  -This invention is not limited to said specific example. That is, the above-described specific examples that are appropriately modified by those skilled in the art are also included in the scope of the present invention as long as they have the characteristics of the present invention. For example, the elements included in each of the specific examples described above, their arrangement, conditions, and the like are not limited to those illustrated, and can be changed as appropriate. Moreover, each element with which embodiment mentioned above is provided can be combined as long as it is technically possible, and the combination of these is also included in the scope of the present invention as long as it includes the features of the present invention.

L11: 1st external ground line L21: 1st internal ground line L22: 2nd internal ground line L23: Connection line Lu, Lv, Lw: Each phase coil (inductive load)
Tgnd1: first ground terminal Tgnd2: second ground terminals Tu, Tv, Tw: connection terminal 4: electronic control unit (ECU)
40: Microcomputer (control unit)
420u, 420v, 420w: MOSFET (low-side switching element)
430: MOSFET (switching element for connection)

Claims (3)

An electronic control unit (4) for controlling inductive loads (Lu, Lv, Lw),
Connection terminals (Tu, Tv, Tw) electrically connected to the inductive load;
A first external ground line (L11) provided outside the electronic control device is electrically connected to the connection terminal via a first internal ground line (L21) provided inside the electronic control device. A first ground terminal (Tgnd1) electrically connected to ground through
Low-side switching elements (420u, 420v, 420w) disposed on the first internal ground line;
A control unit (40) for turning on and off the low-side switching element;
The second internal ground line (L22) different from the first internal ground line is electrically connected to the control unit, and the second external ground line is different from the first external ground line. A second ground terminal (Tgnd2) electrically connected to the ground;
A connection line (L23) connecting the first internal ground line and the second internal ground line;
A connection switching element (430) disposed in the connection line,
The connection switching element is a MOSFET,
A drain terminal of the MOSFET is electrically connected to the first internal ground line;
A source terminal of the MOSFET is electrically connected to the second internal ground line;
When the first external ground line is not disconnected, a ground potential is applied to the gate terminal of the MOSFET, so that the MOSFET is in an off state,
The electronic control device according to claim 1, wherein when the first external ground line is disconnected, a voltage capable of turning on the MOSFET is applied to a gate terminal of the MOSFET, whereby the MOSFET is turned on . The electronic control device according to claim 1 .
The electronic control device according to claim 1, wherein the control unit detects disconnection of the first external ground line based on a gate voltage of the MOSFET. The electronic control device according to claim 2 ,
The electronic control device according to claim 1, wherein when the disconnection of the first external ground line is detected, the control unit applies a voltage capable of turning on the MOSFET to a gate terminal of the MOSFET.

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