Onboard device, information processing method, and program

Abstract

In the present invention, when a current flows in a forward direction with respect to an onboard load, a control unit closes a first upstream-side semiconductor switch and a second downstream-side semiconductor switch, and opens a second upstream-side semiconductor switch and a first downstream-side semiconductor switch. When the current flows in a reverse direction with respect to the onboard load, the control unit opens the first upstream-side semiconductor switch and the second downstream-side semiconductor switch, and closes the second upstream-side semiconductor switch and the first downstream-side semiconductor switch. When performing PWM control with respect to the onboard load, the control unit performs the PWM control of any semiconductor switch from among the upstream-side semiconductor switches and the downstream-side semiconductor switches that are closed, closes the other semiconductor switch, and swaps the PWM-controlled semiconductor switch and the closed switch in accordance with the elapse of a prescribed period, thereby alternately performing PWM control on the upstream-side semiconductor switches and the downstream-side semiconductor switches.

Description

In-vehicle device, information processing method and program

[0001] This application claims priority to Japanese Patent Application No. 2024-050136, filed March 26, 2024, and incorporates by reference all of the contents of that application.

[0002] A vehicle is equipped with a power supply control device (see, for example, Patent Document 1) that controls power supply from a battery to a load. In the power supply control device described in Patent Document 1, a downstream semiconductor fuse is provided in a current path of a current flowing from the battery to the load, and the power supply from the battery to the load is controlled by switching the downstream semiconductor fuse on or off.

[0003] JP 2013-143905 A

[0004] An in-vehicle device according to an embodiment of the present disclosure is an in-vehicle device that drives and controls an in-vehicle load connected to a full bridge formed by a plurality of semiconductor switches, and includes a control unit that performs PWM control on the in-vehicle load, wherein the semiconductor switches of the full bridge include an upstream semiconductor switch made up of a first upstream semiconductor switch and a second upstream semiconductor switch, and a downstream semiconductor switch made up of a first downstream semiconductor switch and a second downstream semiconductor switch, and when a current is to flow in a forward direction through the in-vehicle load, the control unit closes the first upstream semiconductor switch and the second downstream semiconductor switch, and closes the second upstream semiconductor switch and the first downstream semiconductor switch. When the conductive switch is opened to allow a current to flow in the reverse direction to the on-board load, the first upstream semiconductor switch and the second downstream semiconductor switch are opened, and the second upstream semiconductor switch and the first downstream semiconductor switch are closed. When PWM control is performed on the on-board load, one of the upstream semiconductor switch and the downstream semiconductor switch to be closed is PWM controlled, and the other semiconductor switch is closed. By switching between the semiconductor switch to be PWM controlled and the semiconductor switch to be closed as a predetermined period of time passes, the upstream semiconductor switch and the downstream semiconductor switch are alternately PWM controlled.

[0005] FIG. 1 is a schematic diagram illustrating the configuration of an in-vehicle system including an in-vehicle device according to a first embodiment; FIG. 2 is a block diagram illustrating the internal configuration of an in-vehicle device; FIG. 3 is a flowchart illustrating the processing (off-period discontinuous control) of a control unit of an in-vehicle device; FIG. 4 is an explanatory diagram illustrating an example of PWM control of an upstream semiconductor switch and a downstream semiconductor switch alternately; and FIG. 5 is a flowchart illustrating the processing (start of PWM control) of a control unit of an in-vehicle device according to a second embodiment.

[0006] [Problem to be Solved by the Present Disclosure] The power supply control device described in Patent Document 1 does not take into consideration the fact that in a full bridge to which an on-vehicle load is connected, the upstream semiconductor switch and the downstream semiconductor switch are alternately PWM controlled.

[0007] The present disclosure has been made in consideration of the above circumstances, and aims to provide an in-vehicle device or the like that can alternately PWM control upstream semiconductor switches and downstream semiconductor switches in a full bridge to which an in-vehicle load is connected.

[0008] Effect of the Present Disclosure According to one aspect of the present disclosure, it is possible to provide an in-vehicle device or the like that performs PWM control alternately on upstream and downstream semiconductor switches in a full bridge to which an in-vehicle load is connected.

[0009] [Description of Embodiments of the Present Disclosure] First, embodiments of the present disclosure will be listed and described. In addition, at least some of the embodiments described below may be combined in any desired manner.

[0010] (1) An in-vehicle device according to one aspect of the present disclosure is an in-vehicle device that drives and controls an in-vehicle load connected to a full bridge formed by a plurality of semiconductor switches, and includes a control unit that performs PWM control on the in-vehicle load, wherein the semiconductor switches of the full bridge include an upstream semiconductor switch consisting of a first upstream semiconductor switch and a second upstream semiconductor switch, and a downstream semiconductor switch consisting of a first downstream semiconductor switch and a second downstream semiconductor switch, and when a current is to flow in a forward direction through the in-vehicle load, the control unit closes the first upstream semiconductor switch and the second downstream semiconductor switch, and closes the second upstream semiconductor switch and the first downstream semiconductor switch. When the semiconductor switch is opened to allow a current to flow in the reverse direction to the on-board load, the first upstream semiconductor switch and the second downstream semiconductor switch are opened, and the second upstream semiconductor switch and the first downstream semiconductor switch are closed. When PWM control is performed on the on-board load, one of the upstream semiconductor switch and the downstream semiconductor switch to be closed is PWM controlled, and the other semiconductor switch is closed. By switching between the semiconductor switch to be PWM controlled and the semiconductor switch to be closed as a predetermined period of time passes, the upstream semiconductor switch and the downstream semiconductor switch are PWM controlled alternately.

[0011] In this aspect, the in-vehicle device includes a full bridge (H-bridge circuit) and performs open / close control (on / off control) of four semiconductor switches (a first upstream semiconductor switch, a second upstream semiconductor switch, a first downstream semiconductor switch, and a downstream semiconductor switch) that constitute the full bridge to drive and control the in-vehicle device connected to the full bridge. The full bridge does not necessarily have to be housed in the same housing as the in-vehicle device, but may be configured as a separate entity from the housing of the in-vehicle device and communicably connected to the in-vehicle device via a signal line. The full bridge includes an upstream semiconductor switch consisting of a first upstream semiconductor switch and a second upstream semiconductor switch, and a downstream semiconductor switch consisting of a first downstream semiconductor switch and a second downstream semiconductor switch. For example, the first upstream semiconductor switch and the first downstream semiconductor switch are connected in series to a power supply device (+B power supply) such as a lead battery, and the second upstream semiconductor switch and the second downstream semiconductor switch are connected in series. In a full-bridge connection between an on-board device including a motor and the on-board load, one end of the on-board device is connected to a wire (first connecting wire) connecting a first upstream semiconductor switch and a first downstream semiconductor switch, which are connected in series, and the other end of the on-board device is connected to a wire (second connecting wire) connecting a second upstream semiconductor switch and a second downstream semiconductor switch, which are also connected in series. The control unit of the on-board device is configured, for example, by a microcomputer (MCU), and is connected to each semiconductor switch (first upstream semiconductor switch, second upstream semiconductor switch, first downstream semiconductor switch, and downstream semiconductor switch) constituting the full-bridge by signal lines via an input / output interface such as a terminal of the MCU. When a forward current is to flow through the on-board load, the control unit of the on-board device closes (on) the pair of the first upstream semiconductor switch and the second downstream semiconductor switch, and opens (off) the pair of the second upstream semiconductor switch and the first downstream semiconductor switch, thereby rotating the motor included in the on-board load in the forward direction. When the control unit of the vehicle-mounted device flows current in the reverse direction through the vehicle-mounted load, it reverses the rotation of the motor included in the vehicle-mounted load by opening (off) the pair of the first upstream semiconductor switch and the second downstream semiconductor switch and closing (on) the pair of the second upstream semiconductor switch and the first downstream semiconductor switch.Furthermore, when the control unit of the in-vehicle device adjusts the power supplied to the in-vehicle load by increasing or decreasing the power supplied to the in-vehicle load through PWM control, the control unit PWM-controls one of the upstream and downstream semiconductor switches to be closed (ON) and closes (ON) the other. The duty ratio of the PWM control is determined according to the driving mode of the in-vehicle load. That is, when rotating the motor included in the in-vehicle load in the forward direction, the control unit of the in-vehicle device PWM-controls the first upstream semiconductor switch while maintaining the second downstream semiconductor switch in a closed (ON) state, or PWM-controls the second downstream semiconductor switch while maintaining the first upstream semiconductor switch in a closed (ON) state. Similarly, when a motor included in the vehicle load is rotated in the reverse direction, the control unit of the vehicle-mounted device PWM-controls the second upstream semiconductor switch while maintaining the first downstream semiconductor switch in a closed (ON) state, or PWM-controls the first downstream semiconductor switch while maintaining the second upstream semiconductor switch in a closed (ON) state. Furthermore, while continuing to perform the PWM control, the control unit of the vehicle-mounted device PWM-controls the upstream semiconductor switch and the downstream semiconductor switch alternately by switching between the semiconductor switch to be PWM-controlled and the semiconductor switch to be closed (ON) according to the lapse of a predetermined period (switching period). The switching period may be stored in a memory unit of the vehicle-mounted device. In this case, the switching period may be determined based on a rated current value (rated load current value) flowing through the vehicle load. In this case, the switching period may be set to be shorter as the rated current value flowing through the vehicle load increases. Alternatively, when performing PWM control, the switching period may be set to become shorter as the number of switching operations (number of on / off operations) per predetermined processing unit time increases. For example, a semiconductor switch configured with a field effect transistor (FET) or the like tends to generate heat due to switching loss caused by cyclical on / off operations performed by PWM control.Therefore, for example, compared to DC drive that maintains an on-state without periodic switching, it is necessary to select elements with low on-resistance, which may result in relatively high or excessive component costs or size. In response to this, the control unit of the in-vehicle device switches between PWM-controlled semiconductor switches and semiconductor switches maintained in a closed (on) state after a predetermined period has elapsed, i.e., based on a predetermined switching period. For example, when rotating a motor included in an in-vehicle load in the forward direction, the control unit of the in-vehicle device PWM-controls the first upstream semiconductor switch and maintains the second downstream semiconductor switch closed (on) (upstream PWM control state) for a predetermined period, and then switches to a state in which the second upstream semiconductor switch is maintained closed (on) and the first downstream semiconductor switch is PWM-controlled (downstream PWM control state). The control unit of the in-vehicle device switches between an upstream PWM control state and a downstream PWM control state in response to the passage of a predetermined period (switching period), even when a motor included in an in-vehicle load is rotated in reverse. By switching the PWM-controlled semiconductor switches between the upstream semiconductor switch (upstream PWM control state) and the downstream semiconductor switch (downstream PWM control state) in this manner according to the switching period, the amounts of heat generated by the upstream semiconductor switch and the downstream semiconductor switch can be balanced, preventing excessive heat generation by either the upstream semiconductor switch or the downstream semiconductor switch. Therefore, the amount of heat generated by switching losses associated with PWM control can be distributed among the upstream semiconductor switch and the downstream semiconductor switch constituting the full bridge, reducing the amount of heat generated by each individual semiconductor switch. This allows for the use of relatively low-cost or small-sized semiconductor switches, thereby reducing the product cost and size of the in-vehicle device.

[0012] (2) In an in-vehicle device according to one aspect of the present disclosure, when switching the semiconductor switch that is PWM controlled between the upstream semiconductor switch and the downstream semiconductor switch, the control unit performs discontinuous off-period control so that the off-periods in which no current flows through the upstream semiconductor switch and the downstream semiconductor switch are discontinuous before and after the switching.

[0013] In this aspect, the control unit of the in-vehicle device performs control (discontinuous off-period control) to prevent discontinuous off-periods in which no current flows through the upstream semiconductor switch and the downstream semiconductor switch before and after switching the PWM-controlled semiconductor switch. That is, the control unit of the in-vehicle device performs discontinuous off-period control to prevent continuous off-periods in the upstream semiconductor switch and the downstream semiconductor switch before and after switching, by turning the PWM-controlled semiconductor switch off and ending the PWM control before switching, and turning the PWM-controlled semiconductor switch off and starting the PWM control after switching. When switching semiconductor switches that are PWM-controlled and repeatedly turned on and off cyclically according to a duty ratio between the upstream semiconductor switch and the downstream semiconductor switch, if the off-periods of the semiconductor switches before and after switching are continuous, the off-period is essentially doubled relative to the duty ratio, which raises concerns that the rotational speed of a motor included in an in-vehicle load will slow down when the switching is performed. In response to this, the control unit of the in-vehicle device performs discontinuous off-period control, which causes the off-periods during which no current flows through the upstream semiconductor switch and the downstream semiconductor switch to be discontinuous before and after switching, thereby preventing the off-period from becoming longer relative to the duty ratio and maintaining the duty cycle of the pulse width in PWM control. This suppresses motor rattle caused by interruptions in the load current to the in-vehicle load, and enables appropriate drive control of the in-vehicle load.

[0014] (3) In an in-vehicle device according to one aspect of the present disclosure, the control unit performs discontinuous control of the off period by synchronizing the on / off cycles in PWM control of the upstream semiconductor switch and the downstream semiconductor switch before and after switching.

[0015] The control unit of the in-vehicle device synchronizes the on / off cycles in the PWM control of a pair of upstream and downstream semiconductor switches before and after switching the PWM-controlled semiconductor switches, i.e., applies a duty cycle with the same pulse width, thereby performing discontinuous off-period control. In other words, if there are consecutive off-periods in which no current flows through the upstream and downstream semiconductor switches before and after switching, the phases of the PWM control control signals (Hi signal / Lo signal) for these upstream and downstream semiconductor switches will be inverted. However, by synchronizing the on / off cycles in the PWM control of these semiconductor switches, i.e., by making the control signals the same, it is possible to prevent consecutive off-periods. In performing such discontinuous off-period control, the control unit may output control signals (on signal (Hi signal), off signal (Lo signal)) to both the upstream semiconductor switch and the downstream semiconductor switch at the same on / off cycle (synchronizing the duty cycle of the pulse width), and further mask the control signal to on for any semiconductor switch that is controlled to be closed (maintained in the on state). By synchronizing the on / off cycle (duty cycle of the pulse width) in PWM control in this way, discontinuous off-period control can be performed with relatively simple processing.

[0016] (4) In an in-vehicle device according to one aspect of the present disclosure, when switching the semiconductor switch to be PWM controlled between the upstream semiconductor switch and the downstream semiconductor switch, the control unit obtains whether or not current is flowing through the in-vehicle load immediately before the switching, and if current is flowing through the in-vehicle load, starts PWM control from off for the semiconductor switch that will be the target of PWM control after the switching, and if current is not flowing through the in-vehicle load, starts PWM control from on for the semiconductor switch that will be the target of PWM control after the switching, thereby performing discontinuous control during the off period.

[0017] When switching a PWM-controlled semiconductor switch between an upstream semiconductor switch and a downstream semiconductor switch, the control unit of the in-vehicle device acquires whether or not current is flowing through the in-vehicle load immediately before the switching. A current detection unit, for example, composed of a shunt resistor or a Hall element, may be disposed in the in-vehicle load or a wire connected to the in-vehicle load, and the control unit of the in-vehicle device may determine whether or not current is flowing through the in-vehicle load based on a signal from the current detection unit. If current is flowing through the in-vehicle load immediately before the switching, the control unit of the in-vehicle device determines that the PWM-controlled semiconductor switch immediately before the switching is on, and starts PWM control of the PWM-controlled semiconductor switch immediately after the switching from off. If current is not flowing through the in-vehicle load immediately before the switching, the control unit of the in-vehicle device determines that the PWM-controlled semiconductor switch immediately before the switching is off, and starts PWM control of the PWM-controlled semiconductor switch immediately after the switching from on. That is, the control unit of the in-vehicle device performs discontinuous off-period control by varying the signal levels (H / L) output to the upstream semiconductor switch and the downstream semiconductor switch before and after switching. In this way, based on whether or not current is flowing to the in-vehicle load immediately before switching, the control mode for the semiconductor switch that is the target of PWM control after switching can be divided into a control mode that starts from ON and a control mode that starts from OFF, thereby making it possible to efficiently perform discontinuous off-period control.

[0018] (5) In an in-vehicle device according to one aspect of the present disclosure, when the control unit switches the PWM-controlled semiconductor switch between the upstream semiconductor switch and the downstream semiconductor switch, the control unit performs discontinuous control of the off period by starting PWM control from on for the PWM-controlled semiconductor switch immediately after the switching.

[0019] When switching the semiconductor switches to be PWM-controlled between the upstream semiconductor switch and the downstream semiconductor switch, the control unit of the in-vehicle device uniformly starts PWM control from ON for all semiconductor switches to be PWM-controlled immediately after the switching. By starting PWM control for the switched semiconductor switch from the ON state when switching the semiconductor switch in this way, it is possible to reliably prevent continuous OFF periods in which no current flows through the upstream semiconductor switch and the downstream semiconductor switch before and after the switching, and it is possible to perform discontinuous OFF period control with relatively simple control.

[0020] (6) In the in-vehicle device according to one aspect of the present disclosure, the control unit starts PWM control when suppressing an inrush current from flowing to the in-vehicle load.

[0021] In this aspect, the control unit of the in-vehicle device initiates PWM control, for example, when starting to drive the in-vehicle load, i.e., when starting the rotation of a motor included in the in-vehicle load, in order to suppress the flow of inrush current to the in-vehicle load. The control unit of the in-vehicle device initiates drive of the in-vehicle load based on a received message, for example, when receiving a signal from various switches or a message from the in-vehicle ECU via the in-vehicle network. However, if the in-vehicle load includes a motor, there is a concern that an inrush current may flow to the motor. In response to this, the control unit of the in-vehicle device initiates PWM control when detecting a predetermined event that may induce the generation of an inrush current in the in-vehicle load, such as when receiving a signal or message instructing or requesting the start of drive of the in-vehicle load. In this case, when detecting an event related to the drive control of the in-vehicle load, the control unit of the in-vehicle device may determine whether the event induces the generation of an inrush current. When the control unit of the in-vehicle device detects an event that triggers the generation of an inrush current, the control unit starts PWM control, thereby suppressing the flow of inrush current to the in-vehicle load. Then, when continuing PWM control, the control unit of the in-vehicle device alternately switches between the upstream semiconductor switch and the downstream semiconductor switch to perform PWM control, so that the amounts of heat generated by these upstream semiconductor switch and downstream semiconductor switch tend to balance out.

[0022] (7) In the in-vehicle device according to one aspect of the present disclosure, the control unit starts PWM control when varying the rotation speed of the motor included in the in-vehicle load.

[0023] In this aspect, the control unit of the in-vehicle device varies the drive mode of the in-vehicle load based on the received message, for example, when receiving signals from various switches or when receiving a message from the in-vehicle ECU via the in-vehicle network, and at this time varies the rotational speed of the motor included in the in-vehicle load. When varying the rotational speed of the motor included in the in-vehicle load, the control unit of the in-vehicle device starts PWM control to vary the average current value per processing unit time, thereby adjusting the rotational speed of the motor. Then, when continuing PWM control, the control unit of the in-vehicle device alternately switches between the upstream semiconductor switch and the downstream semiconductor switch to perform PWM control, thereby tending to balance the amounts of heat generated by these upstream and downstream semiconductor switches.

[0024] (8) In an in-vehicle device according to one aspect of the present disclosure, the control unit acquires the value of the current flowing through the full bridge, derives the temperature of the wires or the semiconductor switch included in the full bridge based on the acquired current value, and starts PWM control if the derived temperature exceeds a predetermined temperature threshold.

[0025] In this aspect, a control unit of the in-vehicle device acquires a current value flowing through the full bridge, such as a current flowing through an electric wire connecting the full bridge and an in-vehicle load or a current flowing through an energized semiconductor switch, using a current detection unit provided in the full bridge or a current detection function provided in an IPD (Intelligent Power Device) constituting the semiconductor switch. The control unit of the in-vehicle device derives a wire temperature of the electric wire included in the full bridge or an element temperature of the semiconductor switch based on multiple current values ​​periodically acquired from the current detection unit of the full bridge. A storage unit of the in-vehicle device may store a temperature table in which temperatures of the electric wires or semiconductor switches included in the full bridge are defined for multiple periodically acquired current values, and the control unit of the in-vehicle device may derive a temperature corresponding to the current value by referring to the temperature table. Alternatively, the control unit may derive the temperature of the wires or semiconductor switches included in the full bridge based on the acquired current value using, for example, the means disclosed in International Publication WO 2017 / 122781, Japanese Patent Application Publication No. 2009-130944, or Japanese Patent Application Publication No. 2009-226984. The control unit of the in-vehicle device initiates PWM control when the derived temperature exceeds a predetermined temperature threshold. The temperature threshold is stored in a memory unit of the in-vehicle device and is set to a temperature lower than the trip temperature of a fuse (mechanical fuse or semiconductor fuse) set in the full bridge. When the temperature of the wires or semiconductor switches included in the full bridge exceeds the predetermined temperature threshold, the control unit of the in-vehicle device initiates PWM control, thereby reducing the average current flowing through the full bridge and lowering the temperature. Furthermore, when continuing PWM control, the control unit of the in-vehicle device switches between the upstream semiconductor switch and the downstream semiconductor switch and performs PWM control alternately, so that the amounts of heat generated by these upstream semiconductor switch and downstream semiconductor switch tend to become balanced.

[0026] (9) In an in-vehicle device according to one aspect of the present disclosure, the semiconductor switch included in the full bridge or the control unit has a temperature warning function that outputs temperature warning information when the temperature in the full bridge exceeds a predetermined temperature threshold, and the control unit starts PWM control when it acquires the temperature warning information.

[0027] In this aspect, the semiconductor switches included in the full bridge, i.e., the upstream and downstream semiconductor switches, are configured as IPDs (Intelligent Power Devices) with a temperature warning function. When the element temperature of the semiconductor switches exceeds a predetermined temperature threshold, the IPDs including the semiconductor switches output temperature warning information to a control unit, indicating that the temperature in the full bridge has exceeded the predetermined temperature threshold. The entity outputting the temperature warning information to the control unit is not limited to the IPD, but may also be a drive circuit (driver IC) that generates and outputs drive signals, such as gate signals, for the semiconductor switches included in the full bridge. In this case, the drive circuit (driver IC) is communicatively connected to the control unit and generates and outputs drive signals based on control signals from the control unit. It may be included in the control unit or configured as a part of the control unit. Alternatively, a microcomputer included in the control unit may have a temperature warning function that outputs the temperature warning information. The upstream semiconductor switch included in the full bridge corresponds to a high-side switch, and the downstream semiconductor switch corresponds to a low-side switch. The drive circuit (driver IC) may boost the voltage applied to the upstream semiconductor switch, which is a high-side switch, from a power supply (+B power supply) such as a lead battery, and generate and output a drive signal such as a gate signal. When the control unit of the in-vehicle device receives temperature warning information from the IPD or the drive circuit, it starts PWM control, thereby reducing the average current flowing through the full bridge and lowering the temperature of the full bridge. Furthermore, when continuing PWM control, the control unit of the in-vehicle device alternately switches between the upstream semiconductor switch and the downstream semiconductor switch, thereby tending to balance the amounts of heat generated by these upstream and downstream semiconductor switches.

[0028] (10) An information processing method according to an aspect of the present disclosure includes a computer that drives and controls an in-vehicle load connected to a full bridge formed of a plurality of semiconductor switches including an upstream semiconductor switch consisting of a first upstream semiconductor switch and a second upstream semiconductor switch, and a downstream semiconductor switch consisting of a first downstream semiconductor switch and a second downstream semiconductor switch, and when a current is to flow in a forward direction through the in-vehicle load, the computer closes the first upstream semiconductor switch and the second downstream semiconductor switch and opens the second upstream semiconductor switch and the first downstream semiconductor switch, thereby flowing a current in a reverse direction through the in-vehicle load. In this case, the first upstream semiconductor switch and the second downstream semiconductor switch are opened, and the second upstream semiconductor switch and the first downstream semiconductor switch are closed, and when PWM control is performed on the vehicle load, one of the upstream semiconductor switch and the downstream semiconductor switch that is closed is PWM controlled and the other semiconductor switch is closed, and by switching between the semiconductor switch that is PWM controlled and the semiconductor switch that is closed depending on the passage of a predetermined period, a process is performed in which the upstream semiconductor switch and the downstream semiconductor switch are alternately PWM controlled.

[0029] In this aspect, an information processing method can be provided that causes a computer to function as an in-vehicle device that alternately PWM controls an upstream semiconductor switch and a downstream semiconductor switch in a full bridge to which an in-vehicle load is connected.

[0030] (11) A program according to an aspect of the present disclosure includes a program for causing a computer to drive and control an in-vehicle load connected to a full bridge formed of a plurality of semiconductor switches including an upstream semiconductor switch consisting of a first upstream semiconductor switch and a second upstream semiconductor switch, and a downstream semiconductor switch consisting of a first downstream semiconductor switch and a second downstream semiconductor switch, to close the first upstream semiconductor switch and the second downstream semiconductor switch, and open the second upstream semiconductor switch and the first downstream semiconductor switch, thereby causing a current to flow in a reverse direction through the in-vehicle load, when a current is to flow in a forward direction through the in-vehicle load. In this case, the first upstream semiconductor switch and the second downstream semiconductor switch are opened, and the second upstream semiconductor switch and the first downstream semiconductor switch are closed, and when PWM control is performed on the vehicle load, one of the upstream semiconductor switch and the downstream semiconductor switch that is closed is PWM controlled and the other semiconductor switch is closed, and by switching between the semiconductor switch that is PWM controlled and the semiconductor switch that is closed depending on the passage of a predetermined period, a process is performed in which the upstream semiconductor switch and the downstream semiconductor switch are alternately PWM controlled.

[0031] In this aspect, a program can be provided that causes a computer to function as an in-vehicle device that alternately PWM controls an upstream semiconductor switch and a downstream semiconductor switch in a full bridge to which an in-vehicle load is connected.

[0032] [Details of the embodiment of the present disclosure] The present disclosure will be specifically described with reference to the drawings showing the embodiment. An in-vehicle device 1 according to the embodiment of the present disclosure will be described below with reference to the drawings. Note that the present disclosure is not limited to these examples, but is defined by the claims, and is intended to include all modifications within the meaning and scope equivalent to the claims.

[0033] (Embodiment 1) Hereinafter, an embodiment will be described with reference to the drawings. FIG. 1 is a schematic diagram illustrating the configuration of an in-vehicle system S including an in-vehicle device 1 according to embodiment 1. FIG. 2 is a block diagram illustrating the internal configuration of the in-vehicle device 1. The in-vehicle system S is composed of an in-vehicle device 1 mounted on a vehicle C and an in-vehicle load 4 connected to the in-vehicle device 1 via a power line 51. The in-vehicle device 1 is communicably connected to a plurality of in-vehicle ECUs 2 via an in-vehicle network 3, and drives (starts power supply) or stops (cuts off power supply) the in-vehicle load 4 connected to the in-vehicle device 1 in response to messages transmitted from the in-vehicle ECUs 2 or output signals from various sensors, etc.

[0034] When driving the in-vehicle load 4, the in-vehicle device 1 performs PWM control to control the rotation speed of a motor 41 included in the in-vehicle load 4. The motor 41 of the in-vehicle load 4 is connected to a full bridge 6 (H-bridge circuit) provided in the in-vehicle device 1, and is controlled so as to be rotatable in the forward or reverse direction in response to a control signal from a microcomputer 10 of the in-vehicle device 1.

[0035] The vehicle C is equipped with a power supply device 5 configured with a lead battery, an alternator, a secondary battery, or the like. The power supply device 5 and the in-vehicle device 1 are connected by a power line 51. The power supply device 5 and the in-vehicle device 1 are not limited to being directly connected by the power line 51, but may be indirectly connected via an electrical box (junction box) such as a relay box or a fuse box interposed between the power supply device 5 and the in-vehicle device 1.

[0036] The on-board device 1 and one or more on-board loads 4 are connected by a power line 51, and the on-board device 1 distributes power to the multiple on-board loads 4. In other words, the on-board device 1 functions as a power distribution device that distributes power supplied from the power supply device 5 via the power line 51 to the multiple on-board loads 4 arranged downstream in the direction of current flow.

[0037] The vehicle load 4 is an actuator for a door mirror opening / closing device, a seat moving device, or the like, and includes a motor 41 that can rotate in both forward and reverse directions. The vehicle load 4 is connected in a full-bridge configuration 6.

[0038] The in-vehicle device 1 functions as a power supply control device that controls the driving or stopping of the in-vehicle load 4, and may be a device having a relay function such as a CAN gateway. Alternatively, the in-vehicle device 1 may be an integrated ECU (vehicle computer) that controls the entire vehicle C in an integrated manner and has a relay function. Alternatively, the in-vehicle device 1 may be an individual ECU connected under the integrated ECU and disposed in each area of ​​the vehicle C. Alternatively, the in-vehicle device 1 may be configured as a body ECU or the like that controls body actuators of the vehicle C. Alternatively, the in-vehicle device 1 may be a PLB (Power LAN Box) that functions as a power distribution device that distributes and relays power output from a power supply device 5 such as a secondary battery and supplies power to in-vehicle devices such as actuators, in addition to relaying communication.

[0039] The in-vehicle device 1 includes a control unit 11, a storage unit 12, a communication unit 13, and an input / output I / F 14, which may be configured as a package using, for example, a microcomputer 10. Furthermore, the in-vehicle device 1 includes one or more full bridges 6, and an in-vehicle load 4 is connected to the full bridges 6. In the illustration of this embodiment, the in-vehicle device 1 includes one full bridge 6, but this is not limited thereto, and two or more full bridges 6 may be mounted in the in-vehicle device 1.

[0040] The control unit 11 is configured with a CPU (Central Processing Unit) or an MPU (Micro Processing Unit), and performs various control processes and arithmetic processes by reading and executing a control program P (program product) and data pre-stored in the storage unit 12. The control unit 11 outputs control signals such as duty via the input / output I / F 14 and a signal line 140, thereby controlling the opening and closing of the upstream semiconductor switches 7 (first upstream semiconductor switch 71, second upstream semiconductor switch 72) and downstream semiconductor switches 8 (first downstream semiconductor switch 81, second downstream semiconductor switch 82) included in the full bridge 6.

[0041] The storage unit 12 is configured with a volatile memory element such as a random access memory (RAM), a non-volatile memory element such as a read-only memory (ROM), an electrically erasable programmable read-only memory (EEPROM), or a flash memory, or a combination of these storage devices, and stores a control program P (program product) and data to be referenced during processing in advance. The control program P (program product) stored in the storage unit 12 may be a control program P (program product) read from a recording medium M readable by the in-vehicle device 1. Alternatively, the control program P (program product) may be downloaded from an external computer (not shown) connected to a communication network (not shown) and stored in the storage unit 12.

[0042] The communication unit 13 is an input / output interface that uses a communication protocol such as CAN, CAN-FD, or Ethernet (registered trademark), and the control unit 11 communicates with the in-vehicle ECU 2 connected to the in-vehicle network 3 via the communication unit 13. The in-vehicle device 1 may be provided with a plurality of communication units 13.

[0043] The input / output I / F 14 is, for example, a communication interface for serial communication. The input / output I / F 14 includes a plurality of terminals (signal terminals). Signal lines 140 extending to gate terminals of the upstream semiconductor switches 7 (first upstream semiconductor switch 71, second upstream semiconductor switch 72) and downstream semiconductor switches 8 (first downstream semiconductor switch 81, second downstream semiconductor switch 82) included in the full bridge 6 are connected to the terminals, respectively. The signal lines 140 are, for example, a serial cable, a wire harness, or a conductive cable (direct wire) that transmits only one signal.

[0044] The in-vehicle device 1 may further include a drive circuit (driver IC) that generates and outputs drive signals such as gate signals. In this case, the drive circuit (driver IC) is disposed between the upstream semiconductor switch 7, which is a high-side switch, and the microcomputer 10, and is communicatively connected to the control unit 11 via the input / output I / F 14. In this case, the drive circuit (driver IC) or an IPD (Intelligent Power Device) including the semiconductor switches of the full-bridge 6 may have a temperature warning function and output temperature warning information to the control unit 11 (microcomputer 10) when the temperature of the full-bridge 6 exceeds a predetermined temperature threshold.

[0045] The full bridge 6 (H-bridge circuit) includes upstream semiconductor switches 7, which are a first upstream semiconductor switch 71 and a second upstream semiconductor switch 72, and downstream semiconductor switches 8, which are a first downstream semiconductor switch 81 and a second downstream semiconductor switch 82. These upstream semiconductor switches 7 and downstream semiconductor switches 8 are configured with, for example, NchFETs (Field Effect Transistors) or PchFETs. Alternatively, the upstream semiconductor switches 7 and downstream semiconductor switches 8 may be configured with IPDs (Intelligent Power Devices) including semiconductor switching elements such as FETs. The full bridge 6 includes a current detection unit 61 that detects or senses the current value of a current (load current) flowing through an in-vehicle load 4 connected to the full bridge 6.

[0046] A first upstream semiconductor switch 71 and a first downstream semiconductor switch 81 are connected in series to the power supply device 5 (+B power supply), and a second upstream semiconductor switch 72 and a second downstream semiconductor switch 82 are connected in series to the power supply device 5 (+B power supply). The first downstream semiconductor switch 81 and the second upstream semiconductor switch 72 are connected (grounded) to a common ground (G) such as a body frame of the vehicle C, for example.

[0047] A series circuit (first series circuit) formed by the first upstream semiconductor switch 71 and the first downstream semiconductor switch 81 and a series circuit (second series circuit) formed by the second upstream semiconductor switch 72 and the second downstream semiconductor switch 82 are connected in parallel. When the in-vehicle device 1 (motor 41) is connected to the full bridge 6, one end of the in-vehicle device 1 is connected to an electric wire (first connecting electric wire) connecting the first upstream semiconductor switch 71 and the first downstream semiconductor switch 81, which are connected in series, and the other end of the in-vehicle device 1 is connected to an electric wire (second connecting electric wire) connecting the second upstream semiconductor switch 72 and the second downstream semiconductor switch 82, which are connected in series.

[0048] The current detection unit 61 (current sensor) is disposed on an electric wire connected to one end or the other end of the in-vehicle device 1, and is configured by, for example, a shunt resistor or a Hall element. The current detection unit 61 is communicably connected to the control unit 11 (microcomputer 10) via the signal line 140 and the input / output I / F 14, periodically detects or senses the value of the load current flowing through the in-vehicle device 1, and outputs the detected load current value to the control unit 11 (microcomputer 10).

[0049] 3 is a flowchart illustrating the processing (off-period discontinuous control) of the control unit 11 of the in-vehicle device 1. When the vehicle C is stopped or started, the control unit 11 of the in-vehicle device 1 performs the following processing in response to, for example, signals from various switches or messages from the in-vehicle ECU 2.

[0050] The control unit 11 of the in-vehicle device 1 acquires a message regarding the start of driving of the in-vehicle load 4 (S101). The control unit 11 of the in-vehicle device 1 acquires the message regarding the start of driving of the in-vehicle load 4 by, for example, constantly receiving signals from various switches or messages from the in-vehicle ECU 2.

[0051] The control unit 11 of the in-vehicle device 1 determines whether to rotate the in-vehicle load 4 in the forward direction (S102). The in-vehicle load 4 is, for example, an actuator such as a door mirror opening / closing device or a seat moving device, and includes a motor 41 that rotates in both forward and reverse directions. The control unit 11 of the in-vehicle device 1 determines whether to rotate the motor 41 included in the in-vehicle load 4 in the forward direction or in the reverse direction, for example, based on the message ID of the acquired message or a control value included in the payload.

[0052] When the vehicle load 4 is to be rotated forward (S102: YES), the control unit 11 of the in-vehicle device 1 controls each of the multiple semiconductor switches in a manner to rotate the vehicle load 4 forward (S103). When the vehicle load 4 (motor 41) is to be rotated forward, the control unit 11 of the in-vehicle device 1 closes (ON) the first upstream semiconductor switch 71 and the second downstream semiconductor switch 82 and opens (OFF) the second upstream semiconductor switch 72 and the first downstream semiconductor switch 81 to rotate the vehicle load 4 forward. Then, the control unit 11 of the in-vehicle device 1 starts PWM control of one of the pair of the first upstream semiconductor switch 71 and the second downstream semiconductor switch 82, and maintains the other semiconductor switch in a closed (ON) state.

[0053] When the vehicle load 4 is not to be rotated forward (S102: NO), i.e., when the motor 41 of the vehicle load 4 is to be rotated in the reverse direction, the control unit 11 of the in-vehicle device 1 controls each of the multiple semiconductor switches in a manner to rotate the vehicle load 4 in the reverse direction (S1021). When the vehicle load 4 (motor 41) is to be rotated in the reverse direction, the control unit 11 of the in-vehicle device 1 opens (off) the first upstream semiconductor switch 71 and the second downstream semiconductor switch 82 and closes (on) the second upstream semiconductor switch 72 and the first downstream semiconductor switch 81 to rotate the vehicle load 4 in the reverse direction. Then, the control unit 11 of the in-vehicle device 1 starts PWM control of one of the pair of the second upstream semiconductor switch 72 and the first downstream semiconductor switch 81, and maintains the other semiconductor switch in the closed (on) state.

[0054] The control unit 11 of the in-vehicle device 1 determines whether the switching period has elapsed (S104). The switching period is stored, for example, in the storage unit 12 of the in-vehicle device 1, and the control unit 11 of the in-vehicle device 1 acquires the value of the switching period by referring to the storage unit 12. The switching period may be set to, for example, 8 times the switching period (the total value of a single on-period and off-period) when performing PWM control, or between 5 and 10 times the switching period. The control unit 11 of the in-vehicle device 1 has a clock function and measures the elapsed time from the start of PWM control to the current time, or the elapsed time from the previous switching time to the current time, and determines whether the elapsed time has reached the switching period.

[0055] If the switching period has not elapsed (S104: NO), the control unit 11 of the in-vehicle device 1 performs loop processing to execute S104 again. As a result, PWM control in the current mode is continued until the switching period has elapsed. That is, if the current control mode is a control mode in which the upstream semiconductor switch 7 is PWM-controlled and the downstream semiconductor switch 8 is maintained closed (ON), this control mode continues. Alternatively, if the current control mode is a control mode in which the upstream semiconductor switch 7 is maintained closed (ON) and the downstream semiconductor switch 8 is PWM-controlled, this control mode continues. When the in-vehicle load 4 (motor 41) is rotated forward, the upstream semiconductor switch 7 corresponds to the first upstream semiconductor switch 71, and the downstream semiconductor switch 8 corresponds to the second downstream semiconductor switch 82. When the vehicle load 4 (motor 41 ) is rotated in the reverse direction, the upstream semiconductor switch 7 corresponds to the second upstream semiconductor switch 72 , and the downstream semiconductor switch 8 corresponds to the first downstream semiconductor switch 81 .

[0056] If the switching period has elapsed (S104: YES), the control unit 11 of the in-vehicle device 1 switches between the semiconductor switch to be PWM controlled and the semiconductor switch to be closed (ON) using discontinuous off-period control (S105). If the switching period has elapsed since the start of PWM control for either the upstream semiconductor switch 7 or the downstream semiconductor switch 8, or if the switching period has elapsed since the previous switching, the control unit 11 of the in-vehicle device 1 switches between the semiconductor switch to be PWM controlled and the semiconductor switch to be closed (ON). When switching between the semiconductor switch to be PWM controlled and the semiconductor switch to be closed (ON), the control unit 11 of the in-vehicle device 1 performs discontinuous off-period control so that the off periods of the upstream semiconductor switch 7 and the downstream semiconductor switch 8 before and after the switching are not continuous.

[0057] When performing discontinuous off-period control, the control unit 11 of the in-vehicle device 1 may synchronize the on / off cycles in PWM control for the paired upstream semiconductor switch 7 and downstream semiconductor switch 8, i.e., apply duty cycles with the same pulse width. The control unit 11 of the in-vehicle device 1 may output control signals (on signal (Hi signal), off signal (Lo signal)) with the same on / off cycle (synchronizing duty cycles of pulse width) to both the upstream semiconductor switch 7 and the downstream semiconductor switch 8, and further mask the control signal to on for any semiconductor switch that is controlled to be closed (maintained in the on state).

[0058] Alternatively, when performing discontinuous off-period control, the control unit 11 of the in-vehicle device 1 acquires a current value output from the current detection unit 61 provided in the full bridge 6 to determine whether or not current is flowing through the in-vehicle load 4 immediately before switching. If current is flowing through the in-vehicle load 4 immediately before switching, the control unit 11 of the in-vehicle device 1 determines that the semiconductor switch under PWM control immediately before switching is on. If current is not flowing through the in-vehicle load 4 immediately before switching, the control unit 11 of the in-vehicle device 1 determines that the semiconductor switch under PWM control immediately before switching is off.

[0059] If the control unit 11 of the in-vehicle device 1 determines that the PWM-controlled semiconductor switch is on immediately before switching, it starts PWM control of the PWM-controlled semiconductor switch from off immediately after switching, and if it determines that the semiconductor switch is off, it starts PWM control from on. This makes it possible to make the signal levels (H / L) output to the upstream semiconductor switch 7 and the downstream semiconductor switch 8 different before and after switching.

[0060] Alternatively, when performing discontinuous off-period control, the control unit 11 of the in-vehicle device 1 uniformly starts PWM control from on for all semiconductor switches to be PWM-controlled immediately after switching. By starting PWM control for the switched semiconductor switch from the on state when switching the semiconductor switch in this way, it is possible to reliably prevent consecutive off-periods in which no current flows through the upstream semiconductor switch 7 and the downstream semiconductor switch 8 before and after switching.

[0061] As described above, when performing discontinuous off-period control, the control unit 11 of the in-vehicle device 1 can use multiple control modes (discontinuous off-period control modes). The storage unit 12 of the in-vehicle device 1 may store a setting flag that sets which of the multiple control modes (discontinuous off-period control modes) to apply, and the control unit 11 of the in-vehicle device 1 may determine the control mode to apply (discontinuous off-period control mode) based on the setting flag. In this case, if multiple full bridges 6 are connected to the in-vehicle device 1 and an in-vehicle load 4 is connected to each of these full bridges 6, the control mode of the discontinuous off-period control for each full bridge 6 may be determined based on the setting flag corresponding to each full bridge 6. This makes it possible to apply the discontinuous off-period control mode depending on the specifications or characteristics of the in-vehicle load 4 connected to the full bridge 6, thereby improving the availability of the in-vehicle device 1.

[0062] 4 is an explanatory diagram illustrating an example of alternately PWM controlling the upstream semiconductor switch 7 and the downstream semiconductor switch 8. The contents of the above-mentioned processing will be outlined using the illustration of this embodiment.

[0063] 4, the semiconductor switches included in the full bridge 6 are controlled to rotate the vehicle load 4 (motor 41) in the forward direction, with the first upstream semiconductor switch 71 (SW1) and the second downstream semiconductor switch 82 (SW4) closed (on) and the second upstream semiconductor switch 72 (SW2) and the first downstream semiconductor switch 81 (SW3) opened (off). Then, the first upstream semiconductor switch 71 (SW1) and the second downstream semiconductor switch 82 (SW4) are alternately PWM-controlled.

[0064] The period in which the first upstream semiconductor switch 71 (SW1) and the second downstream semiconductor switch 82 (SW4) are alternately PWM controlled is roughly divided into period A and period B. In period A, the second downstream semiconductor switch 82 (SW4) is PWM controlled, and the first upstream semiconductor switch 71 (SW1) is maintained in the ON state. In period B, the first upstream semiconductor switch 71 (SW1) is PWM controlled, and the second downstream semiconductor switch 82 (SW4) is maintained in the ON state.

[0065] The switching period for switching the semiconductor switch subject to PWM control is set to an integer multiple of the switching period (the sum of a single on period and an off period), and in this embodiment, for example, is set to 8. After the switching period has elapsed from the start of PWM control or the point of linear switching, the control unit 11 of the in-vehicle device 1 switches the semiconductor switch subject to PWM control from the first upstream semiconductor switch 71 (SW1) to the second downstream semiconductor switch 82 (SW4), or from the second downstream semiconductor switch 82 (SW4) to the first upstream semiconductor switch 71 (SW1).

[0066] When switching the semiconductor switches that are the subject of PWM control, i.e., when switching from section A to section B or from section B to section A, the control unit 11 of the in-vehicle device 1 performs discontinuous off-period control so that off-periods in which no current flows through the first upstream semiconductor switch 71 (SW1) and the second downstream semiconductor switch 82 (SW4) are not consecutive. The control unit 11 of the in-vehicle device 1 may perform discontinuous off-period control in any of the control modes described above.

[0067] By performing the discontinuous off-period control, it is possible to make the off-period discontinuous so that no duty (pulse) is output and no period in which the load current to the in-vehicle load 4 is off (period in which no load current flows) continues at the timing of switching between sections before and after the switching point. In other words, it is possible to efficiently prevent the semiconductor switches before and after switching from being in the off (Lo) state when the second downstream semiconductor switch 82 (SW4) changes from the off (Lo) state to the off (Lo) state when the first upstream semiconductor switch 71 (SW1) changes from the off (Lo) state.

[0068] The control unit 11 of the in-vehicle device 1 determines whether or not a message regarding stopping the drive of the in-vehicle load 4 has been received (S106). The control unit 11 of the in-vehicle device 1 receives, for example, signals from various switches or messages from the in-vehicle ECU 2 on a regular basis to receive the message regarding stopping the drive of the in-vehicle load 4. If a message regarding stopping the drive of the in-vehicle load 4 has not been received (S106: NO), the control unit 11 performs loop processing to execute the processing from S104 again.

[0069] When a message regarding stopping the driving of the in-vehicle load 4 is received (YES in S106), the control unit 11 of the in-vehicle device 1 opens (turns off) all the semiconductor switches included in the full bridge 6 (S107). When the control unit 11 of the in-vehicle device 1 receives a message regarding stopping the driving of the in-vehicle load 4, for example, from various switches or the in-vehicle ECU 2, the control unit 11 stops the supply of electricity to the in-vehicle load 4 by opening (turning off) all the semiconductor switches included in the full bridge 6.

[0070] 5 is a flowchart illustrating the process (start of PWM control) of the control unit 11 of the in-vehicle device 1 according to embodiment 2. When the vehicle C is stopped or started, the control unit 11 of the in-vehicle device 1 performs the following process in response to, for example, signals from various switches or messages from the in-vehicle ECU 2.

[0071] The control unit 11 of the in-vehicle device 1 receives a message regarding the start of driving of the in-vehicle load 4 (S201). The control unit 11 of the in-vehicle device 1 determines whether or not to rotate the in-vehicle load 4 in the forward direction (S202). The control unit 11 of the in-vehicle device 1 performs the processes of S201 to S202, similar to the processes of S101 to S102 in the first embodiment.

[0072] When the in-vehicle load 4 is to be rotated forward (S202: YES), the control unit 11 of the in-vehicle device 1 controls each of the plurality of semiconductor switches in a manner to rotate the in-vehicle load 4 forward (S203). When controlling each of the plurality of semiconductor switches in a manner to rotate the in-vehicle load 4 forward, the control unit 11 of the in-vehicle device 1 may close (ON) the first upstream semiconductor switch 71 and the second downstream semiconductor switch 82 and open (OFF) the second upstream semiconductor switch 72 and the first downstream semiconductor switch 81 without performing PWM control. In other words, the control unit 11 of the in-vehicle device 1 passes a load current in the forward direction to the in-vehicle load 4 by DC drive that maintains the ON state without performing periodic switching, thereby rotating the motor 41 of the in-vehicle load 4 forward.

[0073] If the vehicle load 4 is not to be rotated in the forward direction (S202: NO), i.e., if the motor 41 of the vehicle load 4 is to be rotated in the reverse direction, the control unit 11 of the vehicle-mounted device 1 controls each of the multiple semiconductor switches in a manner to rotate the vehicle load 4 in the reverse direction (S2021). When controlling each of the multiple semiconductor switches in a manner to rotate the vehicle load 4 in the reverse direction, the control unit 11 of the vehicle-mounted device 1 may open (off) the first upstream semiconductor switch 71 and the second downstream semiconductor switch 82 and close (on) the second upstream semiconductor switch 72 and the first downstream semiconductor switch 81 without performing PWM control. That is, the control unit 11 of the vehicle-mounted device 1 flows a load current in the reverse direction to the vehicle load 4 by DC drive that maintains the on state without performing periodic switching, thereby rotating the motor 41 of the vehicle load 4 in the reverse direction.

[0074] The control unit 11 of the in-vehicle device 1 determines whether to start PWM control (S204). The control unit 11 of the in-vehicle device 1 determines to start PWM control, for example, when suppressing an inrush current from flowing to the in-vehicle load 4. The control unit 11 of the in-vehicle device 1 may determine to start PWM control when detecting a predetermined event that induces the generation of an inrush current in the in-vehicle load 4 (motor 41) by moving (rotating) the in-vehicle load 4 (motor 41) that is in a stopped state, such as when receiving a signal or message instructing or requesting the start of driving the in-vehicle load 4.

[0075] Alternatively, the control unit 11 of the in-vehicle device 1 determines to start PWM control when varying the rotation speed of the motor 41 included in the in-vehicle load 4. The control unit 11 of the in-vehicle device 1 varies the drive mode of the in-vehicle load 4 based on the received message, for example, when receiving signals from various switches or when receiving a message from the in-vehicle ECU 2 via the in-vehicle network 3, and at this time, may determine to start PWM control when varying the rotation speed of the motor 41 included in the in-vehicle load 4.

[0076] Alternatively, the control unit 11 of the in-vehicle device 1 determines to start PWM control when the temperature of the electric wires or semiconductor switches included in the full bridge 6 exceeds a predetermined temperature threshold. The control unit 11 of the in-vehicle device 1 periodically acquires a current value flowing through the full bridge 6, such as a current flowing through an electric wire connecting the full bridge 6 and the in-vehicle load 4 or a current flowing through an energized semiconductor switch, using a current detection unit 61 provided in the full bridge 6 or a current detection function provided in an IPD (Intelligent Power Device) constituting the semiconductor switch. The control unit 11 of the in-vehicle device 1 derives the temperature of the electric wires or semiconductor switches included in the full bridge 6 based on the multiple periodically acquired current values. The control unit 11 of the in-vehicle device 1 may determine to start PWM control when the derived temperature exceeds a predetermined temperature threshold.

[0077] Alternatively, the control unit 11 of the in-vehicle device 1 determines to start PWM control when it receives temperature warning information indicating that the temperature in the full bridge 6 exceeds a predetermined temperature threshold. The control unit 11 of the in-vehicle device 1 is communicatively connected, for example, via the input / output I / F 14, to an IPD constituting a semiconductor switch included in the full bridge 6 or a drive circuit (driver IC) that generates and outputs a drive signal such as a gate signal to the semiconductor switch included in the full bridge 6. The IPD or drive circuit (driver IC) has a temperature warning function and uses the temperature warning function to output temperature warning information indicating that the temperature in the full bridge 6 exceeds a predetermined temperature threshold to the control unit 11 of the in-vehicle device 1. The control unit 11 of the in-vehicle device 1 may determine to start PWM control when it receives temperature warning information from the IPD or drive circuit.

[0078] In the present embodiment, the control unit 11 of the in-vehicle device 1 is described as performing the determination of whether to perform forward rotation and the determination of whether to start PWM control as separate processes, but this is not limiting. The control unit 11 of the in-vehicle device 1 may also determine whether to start PWM control when determining whether to perform forward rotation.

[0079] When it is determined that PWM control should be started (S204: YES), the control unit 11 of the in-vehicle device 1 starts PWM control (S205). When the control unit 11 of the in-vehicle device 1 determines that PWM control should be started according to any of the above-mentioned criteria, the control unit 11 of the in-vehicle device 1 starts PWM control for the semiconductor switch that is controlled by DC drive and maintained in an on state without performing periodic switching. Alternatively, if the control unit 11 of the in-vehicle device 1 has already started PWM control, the control unit 11 of the in-vehicle device 1 continues the PWM control.

[0080] When it is determined that PWM control should not be started (S204: NO), the control unit 11 of the in-vehicle device 1 stops PWM control (S2041). When it is determined that PWM control should not be started, for example, when any of the above-mentioned criteria is not met, the control unit 11 of the in-vehicle device 1 starts DC drive by stopping PWM control of the semiconductor switch. When the control unit 11 of the in-vehicle device 1 has already stopped PWM control, it maintains the stopped state of PWM control (DC drive state).

[0081] After executing S205, the control unit 11 of the in-vehicle device 1 determines whether the switching period has elapsed (S206). If the switching period has elapsed (S206: YES), the control unit 11 of the in-vehicle device 1 switches between the semiconductor switches to be PWM-controlled and the semiconductor switches to be closed (ON) using discontinuous off-period control (S207).

[0082] After executing S2041 or S207, the control unit 11 of the in-vehicle device 1 determines whether or not a message regarding stopping the driving of the in-vehicle load 4 has been received (S208). If a message regarding stopping the driving of the in-vehicle load 4 has been received (S208: YES), the control unit 11 of the in-vehicle device 1 opens (turns off) all of the semiconductor switches included in the full bridge 6 (S209). If the switching period has not elapsed (S206: NO) or if a message regarding stopping the driving of the in-vehicle load 4 has not been received (S208: NO), the control unit 11 of the in-vehicle device 1 performs loop processing to execute the processing from S204 again. The control unit 11 of the in-vehicle device 1 performs the processing from S206 to S209 in the same manner as the processing from S104 to S107 in the first embodiment.

[0083] The embodiments disclosed herein are to be considered as illustrative in all respects and not restrictive. The scope of the present invention is defined by the claims, not by the above meaning, and is intended to include all modifications within the meaning and scope of the claims.

[0084] Multiple claims may be combined with each other regardless of the form of reference. The claims may contain multiple dependent claims that depend on multiple claims. Multiple dependent claims may be contained that depend on multiple dependent claims. If multiple dependent claims that depend on multiple dependent claims are not contained, this does not limit the number of multiple dependent claims that depend on multiple dependent claims.

[0085] C Vehicle S In-vehicle system 1 In-vehicle device 10 Microcomputer (μC) 11 Control unit 12 Storage unit M Recording medium P Control program (program product) 13 Communication unit 14 Input / output I / F 140 Signal line 2 In-vehicle ECU 3 In-vehicle network 4 In-vehicle load 41 Motor 5 Power supply unit 51 Power line 6 Full bridge 61 Current detection unit 7 Upstream semiconductor switch (FET, IPD) 71 First upstream semiconductor switch 72 Second upstream semiconductor switch 8 Downstream semiconductor switch (FET, IPD) 81 First downstream semiconductor switch 82 Second downstream semiconductor switch

Claims

1. An on-vehicle device that drives and controls an on-vehicle load connected to a full bridge composed of a plurality of semiconductor switches, comprising a control unit that performs PWM control on the on-vehicle load, wherein the semiconductor switches of the full bridge include an upstream semiconductor switch consisting of a first upstream semiconductor switch and a second upstream semiconductor switch, and a downstream semiconductor switch consisting of a first downstream semiconductor switch and a second downstream semiconductor switch, wherein the control unit: when flowing a current in a forward direction to the on-vehicle load, closes the first upstream semiconductor switch and the second downstream semiconductor switch and opens the second upstream semiconductor switch and the first downstream semiconductor switch, when flowing a current in a reverse direction to the on-vehicle load, opens the first upstream semiconductor switch and the second downstream semiconductor switch and closes the second upstream semiconductor switch and the first downstream semiconductor switch, and when performing PWM control on the on-vehicle load, of the upstream semiconductor switch and the downstream semiconductor switch that are closed, PWM controls one of the semiconductor switches and closes the other, The in-vehicle device alternately PWM-controls the upstream semiconductor switch and the downstream semiconductor switch by switching between the semiconductor switch to be PWM-controlled and the semiconductor switch to be closed according to the lapse of a predetermined period.

2. The in-vehicle device according to claim 1, wherein when switching the semiconductor switch to be PWM controlled between the upstream semiconductor switch and the downstream semiconductor switch, the control unit performs discontinuous off-period control so that the off-periods in which no current flows through the upstream semiconductor switch and the downstream semiconductor switch are discontinuous before and after the switching.

3. The in-vehicle device according to claim 2, wherein the control unit performs discontinuous control of the off period by synchronizing the on / off cycles in PWM control of the upstream semiconductor switch and the downstream semiconductor switch before and after switching.

4. The in-vehicle device according to claim 2, wherein, when switching the semiconductor switch to be PWM controlled between the upstream semiconductor switch and the downstream semiconductor switch, the control unit obtains whether or not current is flowing to the in-vehicle load immediately before the switching, and if current is flowing to the in-vehicle load, starts PWM control from OFF for the semiconductor switch that will be the target of PWM control after the switching, and if current is not flowing to the in-vehicle load, starts PWM control from ON for the semiconductor switch that will be the target of PWM control after the switching, thereby performing discontinuous control during the OFF period.

5. The in-vehicle device according to claim 2, wherein when switching the PWM-controlled semiconductor switch between the upstream semiconductor switch and the downstream semiconductor switch, the control unit performs discontinuous control of the off period by starting PWM control from on for the PWM-controlled semiconductor switch immediately after switching.

6. The in-vehicle device according to any one of claims 1 to 5, wherein the control unit starts PWM control when suppressing an inrush current from flowing to the in-vehicle load.

7. The in-vehicle device according to any one of claims 1 to 5, wherein the control unit starts PWM control when the rotation speed of the motor included in the in-vehicle load is to be varied.

8. The in-vehicle device according to any one of claims 1 to 5, wherein the control unit acquires a value of a current flowing through the full bridge, derives a temperature of the wires or the semiconductor switches included in the full bridge based on the acquired current value, and starts PWM control when the derived temperature exceeds a predetermined temperature threshold.

9. The in-vehicle device according to any one of claims 1 to 5, wherein the semiconductor switch included in the full bridge or the control unit has a temperature warning function that outputs temperature warning information when the temperature in the full bridge exceeds a predetermined temperature threshold, and the control unit starts PWM control when it acquires the temperature warning information.

10. A computer that drives and controls an on-board load connected to a full bridge composed of multiple semiconductor switches including an upstream semiconductor switch consisting of a first upstream semiconductor switch and a second upstream semiconductor switch, and a downstream semiconductor switch consisting of a first downstream semiconductor switch and a second downstream semiconductor switch, wherein when a current is to flow in a forward direction through the on-board load, the first upstream semiconductor switch and the second downstream semiconductor switch are closed and the second upstream semiconductor switch and the first downstream semiconductor switch are opened, when a current is to flow in a reverse direction through the on-board load, the first upstream semiconductor switch and the second downstream semiconductor switch are opened and the second upstream semiconductor switch and the first downstream semiconductor switch are closed, and when PWM control is to be performed on the on-board load, of the upstream semiconductor switch and the downstream semiconductor switch that are to be closed, one of the semiconductor switches is PWM controlled and the other is closed, an information processing method for executing a process of alternately PWM-controlling the upstream semiconductor switch and the downstream semiconductor switch by switching between the semiconductor switch to be PWM-controlled and the semiconductor switch to be closed in accordance with the passage of a predetermined period of time.

11. A computer that drives and controls an on-vehicle load connected to a full bridge composed of multiple semiconductor switches including an upstream semiconductor switch consisting of a first upstream semiconductor switch and a second upstream semiconductor switch, and a downstream semiconductor switch consisting of a first downstream semiconductor switch and a second downstream semiconductor switch, wherein when a current is to flow in a forward direction through the on-vehicle load, the first upstream semiconductor switch and the second downstream semiconductor switch are closed and the second upstream semiconductor switch and the first downstream semiconductor switch are opened; when a current is to flow in a reverse direction through the on-vehicle load, the first upstream semiconductor switch and the second downstream semiconductor switch are opened and the second upstream semiconductor switch and the first downstream semiconductor switch are closed; when PWM control is to be performed on the on-vehicle load, of the upstream semiconductor switch and the downstream semiconductor switch that are to be closed, one of the semiconductor switches is PWM controlled and the other is closed; a program for executing a process of alternately PWM-controlling the upstream semiconductor switch and the downstream semiconductor switch by switching between the semiconductor switch to be PWM-controlled and the semiconductor switch to be closed according to the lapse of a predetermined period of time.

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