On-vehicle power source device

Abstract

To provide an on-vehicle power source device capable of suppressing power consumption.SOLUTION: An on-vehicle power source device comprises: a semiconductor switch that switches conduction and interruption between two batteries mounted on a vehicle; and a boost circuit that controls the output of gate voltage to the semiconductor switch. The boost circuit performs boosting on the basis of two control modes including a normal mode in which boost control is continuously executed and a power-saving mode in which the boost control is intermittently executed.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present disclosure relates to an on-board power supply device. [Background technology]

[0002] There is an in-vehicle system that has a main battery that stores power from an alternator and a sub-battery that is separate from the main battery, and uses the two batteries to efficiently supply power to each load. In such an in-vehicle system, a semiconductor switch is provided between the batteries, and by shutting off the semiconductor switch in the event of an abnormality, overcharging and over-discharging can be avoided. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2011-234479 Summary of the Invention [Problem to be solved by the invention]

[0004] Under normal circumstances, the semiconductor switch needs to maintain a conducting state in order to supply the power generated by the alternator to the two batteries. To maintain the conducting state, the boost circuit boosts the gate voltage to a constant voltage.

[0005] However, when the vehicle engine is stopped and the alternator is stopped, power is still supplied to some loads, so it is necessary to ensure that the sub-battery, which does not have a large storage capacity, does not run out of power. Accordingly, it is necessary to maintain the semiconductor switch in a conducting state even when the vehicle engine is stopped. Therefore, there is a concern that the power consumption of the boost circuit for maintaining the semiconductor switch in a conducting state will increase.

[0006] The present disclosure has been made to solve the above-mentioned problems, and has an object to provide an on-board power supply device that can reduce power consumption. [Means for solving the problem]

[0007] The on-board power supply device of the present disclosure includes a semiconductor switch that switches between energization and cutoff between two batteries mounted on a vehicle, and a boost circuit that controls the output of a gate voltage to the semiconductor switch, and the boost circuit is an on-board power supply device that boosts voltage based on two control modes: a normal mode that constantly continues boost control, and a power saving mode that intermittently controls boost voltage. Effect of the Invention

[0008] According to the present disclosure, power consumption can be reduced. [Brief description of the drawings]

[0009] [Figure 1] 1 is a schematic diagram illustrating a configuration of an in-vehicle system including an in-vehicle power supply device and the like. [Diagram 2] 2 is a block diagram illustrating an example of the internal configuration of an in-vehicle power supply device. [Diagram 3] 2 is a circuit diagram illustrating an example of an internal configuration of a semiconductor switch and a boost circuit; [Figure 4] 2 is a block diagram illustrating a configuration related to processing of a control unit of an in-vehicle power supply device. FIG. [Diagram 5] 4 is a flowchart illustrating a process of a control unit of an in-vehicle power supply device. [Figure 6] This is a schematic diagram of V1, which represents the voltage from the control unit to the FET driver, and V2, which represents the voltage from the FET driver to the FET in the circuit. [Figure 7] 1 is a schematic diagram showing a voltage from a boost circuit to a gate of a semiconductor switch. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] [Description of the 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 arbitrarily combined.

[0011] (1) An on-board power supply device according to one embodiment of the present disclosure includes a semiconductor switch that switches between energization and cutoff between two batteries mounted on a vehicle, and a boost circuit that controls the output of a gate voltage to the semiconductor switch, and the boost circuit is an on-board power supply device that boosts voltage based on two control modes: a normal mode that constantly continues boost control, and a power saving mode that intermittently controls boost voltage. According to the above configuration, power consumption can be reduced by the power saving mode in which the boost operation is performed intermittently, compared to the normal mode in which the boost control is always continued.

[0012] (2) In the in-vehicle power supply device according to one embodiment of the present disclosure, in the above-mentioned (1), the in-vehicle power supply device may further include a controller, and the controller may switch the control mode based on a state of the vehicle. According to the above configuration, it is possible to switch between the normal mode and the power saving mode.

[0013] (3) In the in-vehicle power supply device according to an embodiment of the present disclosure, as described above in (1) or (2), the semiconductor switch may continue to maintain a conducting state in either of the two control modes. According to the above configuration, when power is supplied to some of the loads even if the alternator is stopped, it is possible to prevent the sub-battery from having a shortage of power.

[0014] (4) In the in-vehicle power supply device according to one embodiment of the present disclosure, in the above-mentioned (2), the control unit may switch the control mode based on an operation of an IG switch provided in the vehicle as the state of the vehicle. According to the above configuration, switching between the normal mode and the power saving mode can be performed due to the operation of the IG switch, and switching between the normal mode and the power saving mode can be performed without having to remember a new cycle.

[0015] (5) In an on-board power supply device according to one embodiment of the present disclosure, in the above (1) or (2), the boost circuit may further include an in-circuit FET and a feedback means for monitoring an input voltage to the semiconductor switch and adjusting the input voltage to the in-circuit FET. According to the above configuration, by monitoring the gate voltage of the semiconductor switch and adjusting the voltage output from the FET driver, it is possible to perform intermittent operation so that the boosted voltage is stabilized within the threshold value.

[0016] (6) In an in-vehicle power supply device according to one embodiment of the present disclosure, in the above (1) or (2), the boost circuit may include an information reading unit that monitors switching of a FET in the circuit and reads information for stopping boost control if an abnormality is detected. According to the above configuration, the potentials on both sides of the switching are compared, and when the amount of current exceeds a threshold, the boost operation is cut off, thereby making it possible to prevent damage to internal components.

[0017] (7) In an on-board power supply device according to one embodiment of the present disclosure, in the above-mentioned (1) or (2), the semiconductor switch may include a plurality of the semiconductor switches, and the plurality of semiconductor switches may be connected in series such that parasitic diodes present in each of the semiconductor switches are in the opposite directions. According to the above configuration, even if a current flows from one of the semiconductor switches, the parasitic diode in the other semiconductor switch is connected in the opposite direction, so that the current can be switched between being energized and cut off in both directions.

[0018] [Details of the embodiment of the present disclosure] Specific examples of the on-board power supply device of the present disclosure will be described below with reference to the drawings. Note that the present invention is not limited to these examples, but is defined by the claims, and is intended to include all modifications within the meaning and scope of the claims.

[0019] <Embodiment 1> Hereinafter, the embodiments will be described with reference to the drawings. Fig. 1 is a schematic diagram illustrating the configuration of an in-vehicle system including an in-vehicle power supply device 100 according to the embodiment 1. This embodiment is a system mounted on a vehicle C, and receives signals related to the state of the vehicle C from an in-vehicle ECU mounted on the vehicle C via an in-vehicle network.

[0020] In this embodiment 1, an alternator 90, a main battery 1, a sub-battery 2, multiple loads 91, and an in-vehicle power supply device 100 are mounted on a vehicle C. The main battery 1, the sub-battery 2, and the multiple loads 91 are electrically connected in parallel to the alternator 90. The in-vehicle power supply device 100 is connected between the main battery 1 and the sub-battery 2, that is, between the two batteries, as a switching means for switching between energization and cutoff, and includes a semiconductor switch 3 and a boost circuit 4, which will be described later.

[0021] The AC current generated by the alternator 90 is converted to DC current by a rectifier (not shown) and adjusted to a set voltage by a regulator (not shown). When the vehicle C is running, the alternator 90 supplies power to the main battery 1, the sub-battery 2, and the load 91. When the engine is stopped, the alternator 90 cannot generate power and is stopped.

[0022] The main battery 1 is a secondary battery such as a lead battery or a lithium battery, and is connected to an alternator 90, a load 91, and a sub-battery 2. The main battery 1 stores the electric power generated by the alternator 90 and supplies the electric power to the load 91.

[0023] The sub-battery 2, like the main battery 1, is a secondary battery such as a lead battery or a lithium battery, but can store less power than the main battery 1. Similarly to the main battery 1, the sub-battery 2 supplies power to a load 91.

[0024] As shown in FIG. 2, the in-vehicle power supply device 100 is provided between a main battery 1 and a sub-battery 2, and has a semiconductor switch 3 that switches between energization and cut-off between the main battery 1 and the sub-battery 2, and a boost circuit 4 that transmits a voltage for switching between energization and cut-off of the semiconductor switch 3.

[0025] The loads 91 are arranged on the main battery 1 side and the sub-battery 2 side based on the in-vehicle power supply device 100. For example, the load 91 that is responsible for the function of safely stopping the vehicle in the event of an abnormality is connected on the sub-battery 2 side of the in-vehicle power supply device 100 so that it can be disconnected together with the sub-battery 2 by the in-vehicle power supply device 100.

[0026] As shown in FIG. 2 or 3, the in-vehicle power supply device 100 has two semiconductor switches 3, a boost circuit 4, and a control unit 5.

[0027] The two semiconductor switches 3 connected between the two batteries have a parasitic diode 30 and a switch section 31, and are connected in series so that the parasitic diodes 30 face in the opposite direction to each other, that is, so that the anode and cathode face in the opposite direction in the current flow.

[0028] By connecting the parasitic diodes 30 of the two semiconductor switches 3 in series in the opposite directions, it is possible to prevent current from flowing through the parasitic diodes 30 when the two switch sections 31 are turned off.

[0029] As shown in FIG. 3 or FIG. 4, the boost circuit 4 has a capacitor 45, a coil 44 for storing energy, an in-circuit FET 41 that plays the role of a switch for boosting, and a FET driver 40 for operating the in-circuit FET 41. The boost circuit 4 boosts the voltage sent from the main battery 1 side rather than the semiconductor switch 3, and the boosted voltage is input to the gate of the semiconductor switch 3. When the in-circuit FET 41 is turned on, a current flows to the switch via the coil 44. The coil 44 tries to prevent an increase in current, so energy is stored in the coil 44. When the in-circuit FET 41 is turned off, the coil 44 releases the energy that has been stored up until now, and the capacitor 45 is charged. As a result, a voltage higher than the voltage supplied from the alternator 90 or the main battery 1 is output, and the output voltage is used as the gate voltage of the semiconductor switch 3, thereby controlling the switch unit 31 to be switched on and off.

[0030] By providing the boost circuit 4 in this manner, even if the semiconductor switch 3, such as an n-channel FET, is arranged as a high-side switch that is upstream of the load 91 in the direction of current flow, it is possible to perform switching control (on / off control) of the semiconductor switch 3.

[0031] The FET driver 40 has an output SW for controlling the in-circuit FET 41, an input VIN from the battery, a signal input EN from the control unit 5, and an input GND from the vehicle C earth.

[0032] The control unit 5 is configured with a CPU (Central Processing Unit) or an MPU (Micro Processing Unit) and is a control device that switches between a signal for turning on the in-circuit FET 41 and a signal for turning off the in-circuit FET 41, and outputs the signal to the FET driver 40 in the boost circuit through the circuit line V1. The control unit 5 generates a high signal and a low signal, and transmits different signals depending on the mode.

[0033] 4, the control unit 5 acquires the on / off state of the IG switch 60 from the communication unit 50. The control unit 5 derives a control mode from the storage unit 51 based on the information on the vehicle state acquired from the communication unit 50, and transmits a signal related to the corresponding control mode to the boost circuit 4.

[0034] The communication unit 50 is a semiconductor switch 3 that is a communication interface compatible with a protocol such as LIN (Local Interconnect Network), CAN (Controller Area Network), or Ethernet (registered trademark). The control unit 5 communicates with the communication unit 50 using a predetermined protocol such as LIN, and reads the state of the IG switch 60.

[0035] The storage unit 51 is composed of a volatile memory element such as a random access memory (RAM) or a non-volatile memory element such as a read only memory (ROM), an electrically erasable programmable ROM (EEPROM), or a flash memory. The storage unit 51 stores programs and data for executing the programs. These programs may be stored as programs read from a recording medium (not shown) that can be read by the control unit 5 of the in-vehicle power supply device 100. Alternatively, the control unit 5 of the in-vehicle power supply device 100 may download these programs from an external computer (not shown) connected to a communication network (not shown) and store them in the storage unit 51.

[0036] 5 is a flowchart illustrating the processing of the control unit 5. The control unit 5 of the in-vehicle power supply device 100 performs the following processing in response to an operation on the IG switch 60, for example.

[0037] The control unit 5 of the in-vehicle power supply device 100 acquires information about the state of the vehicle C by receiving, via the communication unit 50, communication data such as a CAN message transmitted in response to operation of the IG switch 60 (S101).

[0038] The storage unit 51 of the in-vehicle power supply device 100 stores, for example, in a table format or a parameter sheet, control modes, such as normal mode or power saving mode, corresponding to classifications of vehicle states, for example classifications according to whether the IG switch 60 is in an on state or an off state. The control unit 5 of the in-vehicle power supply device 100 derives the control mode according to the state of the vehicle C by referring to the storage unit 51, and determines whether the control mode is the normal mode or the power saving mode (S102).

[0039] The control unit 5 of the in-vehicle power supply device 100 determines whether the control mode is the power saving mode or not, and performs the following operation depending on the control mode based on the determination result (S103). Note that instead of determining whether the control mode is the power saving mode, it may also determine whether the control mode is the normal mode.

[0040] If the control mode is the normal mode (S103: NO), the control unit 5 of the in-vehicle power supply device 100 transmits a normal mode signal to the boost circuit 4, and drives the boost circuit 4 (S1031). If the control mode is the power saving mode (S103: YES), the control unit 5 of the in-vehicle power supply device 100 transmits a power saving mode signal to the boost circuit 4, and drives the boost circuit 4 (S104). The control unit 5 of the in-vehicle power supply device 100 may perform a loop process to execute the process from S101 again after executing the process of S104 or S1031.

[0041] The two control modes are explained below.

[0042] The normal mode is set when the IG switch 60 is on, that is, when the engine is running, and the alternator 90 generates electricity and supplies it to the two batteries. The generated electricity is ultimately consumed by the load 91.

[0043] In the normal mode, the control unit 5 is set to continuously output a high signal, and while the high signal is being output, the in-circuit FET 41 continues to perform on-off switching. The voltage boosted by the switching operation of the in-circuit FET 41 is input to the gate of the semiconductor switch 3.

[0044] The power saving mode is set when the IG switch 60 is off, that is, when the engine is stopped, the alternator 90 does not generate electricity, and power is stored in the two batteries. There are loads 91, such as the lamp system of an automobile, that need to be operated even when the engine is stopped.

[0045] In the power saving mode, the amount of power is limited compared to the normal mode because the alternator 90 does not operate. Furthermore, if the storage capacity of the sub-battery 2 is smaller than that of the main battery 1, it is expected that there will be a shortage of additional power. Therefore, in order to prevent a power shortage of the sub-battery 2, it is necessary to keep the semiconductor switch 3 on in the power saving mode and supply power from the main battery 1 as well.

[0046] In the power saving mode, the control unit 5 is set to output high and low signals alternately. While the high and low signals are being output alternately, the in-circuit FET 41 intermittently boosts the voltage, and the boosted voltage is input to the semiconductor switch 3.

[0047] Fig. 6 shows V1 representing the voltage of the signal input from the control unit 5 to the FET driver 40, and V2 representing the voltage of the signal input from the FET driver 40 to the in-circuit FET 41. Fig. 7 is a schematic diagram showing the gate voltage in the semiconductor switch 3. The control mode has a high signal with a 5V waveform and a low signal with a 0V waveform.

[0048] In order to maintain the on state of the semiconductor switch 3, the voltage boosted by the boost circuit 4 is input to the gate of the switch unit 31. In the normal mode, the boost circuit 4 always boosts the voltage to 24V, and in the power saving mode, the voltage is intermittently boosted between 19V and 24V.

[0049] The boosted voltage is input to the switch portion 31 of the semiconductor switch 3, so that the semiconductor switch 3 maintains the on state in the two modes.

[0050] In normal mode, the control unit 5 constantly transmits a high signal, outputting a constant 5V waveform to the FET driver 40. While a voltage of 5V is being input to the FET driver 40, the in-circuit FET 41 continues to open and close, so the boost circuit 4 boosts a voltage of 12V to 24V and sends it to the gate of the switch unit 31. While a voltage of 24V continues to be input from the boost circuit 4, the semiconductor switch 3 maintains its on state.

[0051] In the power saving mode, the control unit 5 alternately transmits high and low signals at regular intervals, and outputs them to the FET driver 40 so that the waveforms of 5V and 0V alternate. The FET driver 40 keeps opening and closing the in-circuit switch while a voltage of 5V is being input. While a voltage of 0V is being input, the signal sent to the gate of the in-circuit switch also stops. Therefore, the boost circuit 4 intermittently boosts the voltage of 12V and sends it to the gate of the switch unit 31. Since the boost circuit 4 is provided with a capacitor 45, the voltage that was once boosted gradually decreases while the in-circuit switch stops opening and closing. When the gate voltage drops to a certain voltage, the semiconductor switch 3 continues to maintain a voltage between 18 and 24V by boosting it again, so that the semiconductor switch 3 is maintained in the on state. Therefore, the high signal for boosting the gate voltage is output at a shorter time rate than the low signal for gradually decreasing the gate voltage.

[0052] [Another embodiment of the present disclosure] The embodiments disclosed herein are illustrative in all respects and should not be considered as limiting. 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 scope and meaning equivalent to the claims.

[0053] The on-board power supply apparatus 100 may include a feedback means 43 . The feedback means 43 controls the gate voltage of the semiconductor switch 3 to be within a certain range. For example, the feedback means 43 controls the on / off of the in-circuit FET 41 by PFM (Pulse Frequency Modulation) control.

[0054] Specifically, the feedback means 43 monitors the boosted voltage sent to the gate of the semiconductor switch 3, and performs feedback FB to the FET driver 40. The FET driver 40 that receives the feedback FB controls the switching frequency of V2 so that the gate voltage of the semiconductor switch 3 falls within a certain range.

[0055] In the normal mode, since the control unit 5 always sends a High signal to the FET driver 40, the feedback means 43 continuously controls the switching frequency of V2 so that the gate voltage of the semiconductor switch 3 is 24V.

[0056] In the power saving mode, the feedback means 43 continues to boost the gate voltage of the semiconductor switch 3 while the control unit 5 is sending a High signal to the FET driver 40. Thereafter, the switching frequency of V2 is controlled so that it does not exceed 24 V until the next Low signal is sent from the control unit.

[0057] The feedback means may perform PWM (Pulse Width Modulation) control instead of PFM control. While PFM control controls the switching frequency of V2, PWM control adjusts the gate voltage of the semiconductor switch 3 by controlling the switching on / off ratio.

[0058] The boost circuit 4 may include an information reading unit 42 . The information reading unit 42 reads the current difference between the in-circuit switch and the GND line, and when an abnormality such as overboost occurs, it stops the in-circuit FET 41 so as to temporarily shut off the gate of the semiconductor switch 3. This makes it possible to protect the circuit from overcurrent. To restart the boost circuit, the IG switch 60 is operated to start the processing of the control unit 5.

[0059] The orientation of the parasitic diode 30 is merely an example and is not limited thereto. The parasitic diodes 30 of the semiconductor switches 3 shown in Fig. 3 are arranged so that the anodes are on the inside and the cathodes are on the outside. These may be arranged in series in the opposite directions, for example, so that the cathodes are on the inside and the cathodes are on the outside.

[0060] The number of semiconductor switches 3 is not limited to two. In the first embodiment, the two semiconductor switches 3 are arranged in anti-series, but this is not limiting. For example, even when four semiconductor switches are arranged in a combination of series and parallel, the anodes of the parasitic diodes 30 are arranged facing each other and the cathodes are arranged facing each other to prevent reverse current flow.

[0061] The state of the IG switch 60 is an example of the vehicle state, and is not limited to this. For example, even if the IG switch 60 is on, the vehicle C may be switched to the power saving mode when the vehicle C is stopped.

[0062] In an electric vehicle that does not have an engine, the control mode may be switched depending on whether a power switch is on or off.The control mode may also be switched when the on-board ECU receives a signal from a device outside the vehicle, such as a smart key that locks and unlocks the vehicle doors.

[0063] In addition, multiple claims described in the claims can be combined with each other regardless of the reference form. Multiple dependent claims that depend on multiple claims may be described in the claims. Multiple dependent claims that depend on multiple dependent claims may be described. Even if multiple dependent claims that depend on multiple dependent claims are not described, this does not limit the description of multiple dependent claims that depend on multiple dependent claims. [Explanation of symbols]

[0064] C…Vehicle 100…In-vehicle power supply unit 1. Main battery 2. Sub battery 3. Semiconductor switch 30...Parasitic diode 31...Switch section 4. Boost circuit 40…FET driver 41...In-circuit FET 42... Information reading unit 43...Feedback methods 44…Coil 45…Capacitor 5. Control section 50…Communications Department 51...Storage section 60…IG switch 90…Alternator 91...Load

Claims

1. A semiconductor switch that switches between energization and cutoff between two batteries mounted in a vehicle; a boost circuit for controlling an output of a gate voltage to the semiconductor switch, The boost circuit boosts the voltage based on two control modes: a normal mode in which boost control is always continued, and a power saving mode in which boost control is intermittently performed. In-vehicle power supply.

2. The vehicle-mounted power supply device further includes a control unit, The control unit switches the control mode based on a state of the vehicle.

2. The vehicle-mounted power supply device according to claim 1.

3. The semiconductor switch continues to maintain a conductive state in both of the two control modes.

3. The vehicle-mounted power supply device according to claim 1 or 2.

4. The control unit switches the control mode based on an operation of an IG switch provided in the vehicle as a state of the vehicle. The vehicle-mounted power supply device according to claim 2.

5. The boost circuit further includes an in-circuit FET, A feedback means is provided for monitoring an input voltage to the semiconductor switch and adjusting an input voltage to the FET in the circuit.

3. The vehicle-mounted power supply device according to claim 1 or 2.

6. The boost circuit includes an information reading unit that monitors switching of an FET in the circuit and reads information for stopping boost control when an abnormality is detected.

3. The vehicle-mounted power supply device according to claim 1 or 2.

7. The semiconductor switch includes a plurality of the semiconductor switches, The plurality of semiconductor switches are connected in series such that the parasitic diodes present in each of the semiconductor switches are in the opposite directions.

3. The vehicle-mounted power supply device according to claim 1 or 2.

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