Power supply control device, power supply control method and computer program

Abstract

In a power supply control device, power supply to a load (11) via a power supply switch (30) is controlled. A drive circuit (34) switches the power supply switch (30) on or off. When the drive circuit (34) switches the power supply switch (30) from off to on, a waveform value related to the current waveform of the current flowing to the load (11) is output from a waveform value detection unit (42) to a microcomputer (21). The microcomputer (21) determines a power supply control condition related to power supply control to the load (11) based on the waveform value input from the waveform value detection unit (42).

Description

Technical Field

[0001] The present disclosure relates to a power supply control device, a power supply control method, and a computer program.

[0002] This application claims the priority based on Japanese Application No. 2018-161492 filed on August 30, 2018, and all the contents described in the Japanese Application are cited by reference. Background Art

[0003] Patent Document 1 discloses a vehicle power supply control device for controlling power supply from a power source to a load. In the power supply control device, power is supplied from the power source to the load via a switch. The power supply to the load is controlled by switching the switch on or off.

[0004] The power supply control device described in Patent Document 1 stores customized information indicating the operating specifications of the load. Power supply control conditions related to power supply control are determined based on the operating specifications indicated by the customized information. The power supply control conditions include, for example, whether to perform PWM (Pulse Width Modulation) control on the switch.

[0005] Prior Art Literature

[0006] Patent Literature

[0007] Patent Document 1: Japanese Patent Application Publication No. 2016-43872 Summary of the invention

[0008] A power supply control device in one form of the present disclosure controls power supply to a load via a switch, wherein the power supply control device comprises: a switching unit that switches the switch to be on or off; and a determining unit that determines a power supply control condition related to power supply control to the load based on a waveform value related to a current waveform of a current flowing to the load when the switching unit switches the switch from being off to being on.

[0009] A power supply control method according to one form of the present disclosure includes the following steps: switching a switch to on or off; when the switch is switched from off to on, obtaining a waveform value related to a current waveform of a current flowing to a load; and determining a power supply control condition related to power supply control to the load based on the obtained waveform value.

[0010] A computer program in one form of the present disclosure causes a computer to execute the following steps: instructing a switch to switch on or off; when the switch is switched from off to on, obtaining a waveform value related to the current waveform of the current flowing to a load; and determining a power supply control condition related to the power supply control to the load based on the obtained waveform value.

[0011] It should be noted that the present disclosure can be implemented not only as a power supply control device having such a characteristic processing unit, but also as a power supply control method that sets the above characteristic processing as steps, or as a computer program for causing a computer to execute the above steps. Moreover, the present disclosure can be implemented as a semiconductor integrated circuit that implements part or all of the power supply control device, or as a power supply system including the power supply control device. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 It is a block diagram showing a main part configuration of a power supply system according to the present embodiment.

[0013] Figure 2 This is a block diagram showing the main structure of the control machine.

[0014] Figure 3 It is an explanatory diagram of multiple waveform values.

[0015] Figure 4 This is a block diagram showing the main structure of a microcomputer.

[0016] Figure 5 This is a graph showing a power supply control table.

[0017] Figure 6 This is a graph represented by a waveform value table.

[0018] Figure 7 This is a flowchart showing the procedure of the power supply control process.

[0019] Figure 8 This is a flowchart showing the procedure of the electric wire protection process.

[0020] Fig. 9 This is a flowchart showing the procedure of the connection detection process.

[0021] Fig.10 This is a flowchart showing the procedure of the update process.

[0022] Fig.11 This is a flowchart showing the procedure of the update process. DETAILED DESCRIPTION

[0023] [Problems to be Solved by the Present Disclosure]

[0024] The power supply control device described in Patent Document 1 has a connection terminal, to which a load is connected. Current flows in the order of a power supply, a switch, a connection terminal, and a load, and power is supplied to the load. The load connected to the connection terminal can be changed. When the load connected to the connection terminal is changed, it is necessary to update the power supply control condition to a condition corresponding to the changed load.

[0025] In the power supply control device described in Patent Document 1, customized information corresponding to the changed load is received from other devices, and the power supply control conditions are updated based on the received customized information. In this case, customized information needs to be sent from other devices every time the load changes, so there is a problem that it takes a long time to update the power supply control conditions.

[0026] Therefore, an object of the present invention is to provide a power supply control device, a power supply control method, and a computer program in which the time required for updating power supply control conditions is short.

[0027] [Effects of the present disclosure]

[0028] According to the present disclosure, the time required to change the power supply control conditions is short.

[0029] [Description of Embodiments of the Present Disclosure]

[0030] First, embodiments of the present disclosure will be described by way of example. At least a part of the embodiments described below may be arbitrarily combined.

[0031] (1) A power supply control device in one form of the present disclosure controls power supply to a load via a switch, wherein the power supply control device comprises: a switching unit that switches the switch to be on or off; and a determining unit that determines a power supply control condition related to power supply control to the load based on a waveform value related to a current waveform of a current flowing to the load when the switching unit switches the switch from being off to being on.

[0032] (2) A power supply control device in one form of the present disclosure comprises: a connector, which is arranged in a current path of the current flowing through the switch, and the load can be detachably connected to the connector; and a connection detection unit, which detects the connection of the load to the connector, and the switching unit switches the switch from off to on when the connection detection unit detects the connection.

[0033] (3) In the power supply control device according to one aspect of the present disclosure, the switching unit switches the switch to OFF when a current value of the current flowing to the load becomes equal to or greater than a current threshold, and the power supply control condition includes the current threshold.

[0034] (4) A power supply control device according to one aspect of the present disclosure includes: a voltage detection circuit that detects a voltage value of a voltage applied to the load; and a correction unit that corrects the waveform value based on the voltage value detected by the voltage detection circuit.

[0035] (5) A power supply control device according to one aspect of the present disclosure includes: a temperature estimating unit that estimates an ambient temperature of the load; and a second correcting unit that corrects the waveform value based on the ambient temperature estimated by the temperature estimating unit.

[0036] (6) A power supply control device according to one aspect of the present disclosure includes a determination unit that determines a type of the load based on the waveform value, and the decision unit determines the power supply control condition to be a power supply control condition corresponding to the type determined by the determination unit.

[0037] (7) A power supply control method according to one form of the present disclosure includes the following steps: switching a switch to on or off; when the switch is switched from off to on, obtaining a waveform value related to a current waveform of a current flowing to a load; and determining a power supply control condition related to power supply control to the load based on the obtained waveform value.

[0038] (8) A computer program in one form of the present disclosure causes a computer to execute the following steps: instructing a switch to switch to on or off; when the switch is switched from off to on, obtaining a waveform value related to the current waveform of the current flowing to a load; and determining a power supply control condition related to the power supply control to the load based on the obtained waveform value.

[0039] In the power supply control device, power supply control method and computer program of one form described above, the power supply control condition is determined based on the waveform value related to the current waveform when the switch is switched from off to on. Therefore, when the load to which the power is supplied via the switch changes, the current waveform, i.e., the waveform value, changes, and thus the power supply control condition is immediately updated. Therefore, the time required for changing the power supply control condition is short. The waveform value is an inrush current value, a stable current value, or a rising speed of the current value, etc. The power supply control condition includes whether PWM control is performed for the on and off of the switch or the duty cycle of the PWM signal, etc.

[0040] In the power supply control device of the above-mentioned one aspect, when a load is connected to the connector, the connection is detected and the switch is switched from off to on. Then, the power supply control condition is determined based on the waveform value related to the current waveform.

[0041] In the power supply control device of the above-described aspect, when the current value of the current flowing to the load becomes equal to or greater than a current threshold, the switch is switched to be OFF. The current threshold is determined based on a waveform value related to the current waveform.

[0042] In the power supply control device of one aspect described above, the waveform value is corrected based on the voltage value of the voltage applied to the load, such as the voltage value of the battery. For example, the acquired waveform value is corrected to the waveform value when the voltage value of the voltage applied to the load is a predetermined voltage value.

[0043] In the power supply control device of the above-mentioned aspect, the waveform value is corrected based on the estimated ambient temperature of the load. For example, the acquired waveform value is corrected to a waveform value when the ambient temperature of the load is a predetermined temperature.

[0044] In the power supply control device of the above-described aspect, the type of the load is identified based on the waveform value, and the power supply control condition is determined to be a power supply control condition corresponding to the identified type.

[0045] [Details of the embodiments of the present disclosure]

[0046] Hereinafter, specific examples of the power supply system according to the embodiment of the present disclosure will be described with reference to the drawings. It should be noted that the present invention is not limited to these examples, but is disclosed by the claims, and is intended to include all changes within the meaning and scope equivalent to the claims.

[0047] Figure 1 1 is a block diagram showing the main structure of the power supply system 1 of the present embodiment. The power supply system 1 is preferably mounted on a vehicle and includes a battery 10, a load 11, a power supply control device 12, and outer connectors A1, A2, and A3. The power supply control device 12 includes a controller 20, a microcomputer (hereinafter referred to as a microcomputer) 21, and inner connectors B1, B2, and B3.

[0048] The positive electrode of the battery 10 is connected to the external connector A1. The negative electrode of the battery 10 is grounded. One end of the load 11 is connected to the external connector A2. The other end of the load 11 is connected to the external connector A3.

[0049] In the power supply control device 12, one end of the electric wire W is connected to the inside connector B1. The other end of the electric wire W is connected to the inside connector B2. The control machine 20 is arranged in the middle of the electric wire W. The control machine 20 is connected to the microcomputer 21. The inside connector B3 is grounded.

[0050] The outer connectors A1, A2, and A3 are detachably connected to the inner connectors B1, B2, and B3, respectively. When the outer connectors A2 and A3 are connected to the inner connectors B2 and B3, respectively, the load 11 is connected to the inner connectors B2 and B3. When the outer connectors A1, A2, and A3 are connected to the inner connectors B1, B2, and B3, respectively, the positive electrode of the battery 10 and one end of the load 11 are connected to the control machine 20, and the other end of the load 11 is grounded.

[0051] The microcomputer 21 outputs a high-level voltage, a low-level voltage or a PWM signal to the control machine 20. The PWM signal is composed of a high-level voltage and a low-level voltage. In the PWM signal, switching from a low-level voltage to a high-level voltage or from a high-level voltage to a low-level voltage is performed periodically. The duty cycle of the PWM signal is the ratio of the period during which the PWM signal displays a high-level voltage in one cycle. The unit of the duty cycle of the PWM signal is a percentage.

[0052] The control machine 20 has a power switch 30 (see Figure 2 ). When the voltage input from the microcomputer 21 is switched from a low-level voltage to a high-level voltage, the control machine 20 switches the power switch 30 from off to on. As a result, current flows from the positive electrode of the battery 10 in the order of the power switch 30 and the load 11, and power is supplied from the battery 10 to the load 11. Furthermore, when the voltage input from the microcomputer 21 is switched from a high-level voltage to a low-level voltage, the control machine 20 switches the power switch 30 from on to off. As a result, the power supply from the battery 10 to the load 11 is stopped.

[0053] When the PWM signal is input from the microcomputer 21, the control machine 20 switches the power supply switch 30 from off to on when the voltage indicated by the PWM signal switches from a low level voltage to a high level voltage. Thus, power is supplied from the battery 10 to the load 11. In the same case, when the voltage indicated by the PWM signal switches from a high level voltage to a low level voltage, the control machine 20 switches the power supply switch 30 from on to off. Thus, the power supply from the battery 10 to the load 11 is stopped.

[0054] When the microcomputer 21 outputs the PWM signal to the controller 20, power corresponding to the duty ratio of the PWM signal is supplied to the load 11. The larger the duty ratio of the PWM signal, the larger the average value of the power supplied to the load 11.

[0055] As described above, the control machine 20 controls the supply of power from the battery 10 to the load 11 via the power switch 30 .

[0056] The load 11 is an electrical device mounted on the vehicle. The load 11 operates using the power supplied from the battery 10. When replacing the load 11, the user disconnects the connection between the outer connector A2 and the inner connector B2, and disconnects the connection between the outer connector A3 and the inner connector B3, and connects the outer connectors A2 and A3 connected to the new load 11 to the inner connectors B2 and B3. Thus, the new load 11 is connected to the inner connectors B2 and B3 of the power supply control device 12.

[0057] Figure 2: is a block diagram showing the main part structure of the control machine 20. The control machine 20 has a current output circuit 31, a voltage detection circuit 32, a return diode 33, a drive circuit 34, an AND circuit 35, a variable resistor 36, a comparator 37, a DC power supply 38, a latch circuit 39, an inverter 40, a filter circuit 41, a waveform value detection unit 42, an adjustment unit 43, a voltage dividing resistor 44, a detection switch 45, a switching unit 46, and a temperature estimation unit 47 in addition to the power supply switch 30.

[0058] The power switch 30 is an N-channel FET (Field Effect Transistor). The AND circuit 35 has two input terminals and one output terminal. The comparator 37 has a positive terminal, a negative terminal and an output terminal. The inverter 40 has an input terminal and an output terminal.

[0059] A power supply switch 30 and a current output circuit 31 are arranged in the middle of the electric wire W. The drain of the power supply switch 30 is connected to the inner connector B1. As described above, the inner connector B1 is connected to the outer connector A1, and the outer connector A1 is connected to the positive electrode of the battery 10. The source of the power supply switch 30 is connected to the current output circuit 31. The current output circuit 31 is also connected to the inner connector B2. The inner connector B2 is connected to the outer connector A2, and the outer connector A2 is connected to one end of the load 11.

[0060] The voltage detection circuit 32, the cathode of the return diode 33, and the microcomputer 21 are connected to the middle of the wire W. The voltage detection circuit 32 is connected to the drain of the power switch 30 and the microcomputer 21. The cathode of the return diode 33 is connected to the connection node between the source of the power switch 30 and the current output circuit 31. The anode of the return diode 33 is grounded. The microcomputer 21 is connected to the connection node between the current output circuit 31 and the inner connector B2.

[0061] The gate of the power switch 30 is connected to the drive circuit 34. The drive circuit 34 is connected to the output end of the AND circuit 35. The current output circuit 31 is connected to one end of the variable resistor 36. The other end of the variable resistor 36 is grounded. The connection node between the current output circuit 31 and the variable resistor 36 is connected to the positive end of the comparator 37. The negative end of the comparator 37 is connected to the positive electrode of the DC power supply 38. The negative electrode of the DC power supply 38 is grounded.

[0062] The output terminal of the comparator 37 is connected to the latch circuit 39. The latch circuit 39 is also connected to the input terminal of the inverter 40. One input terminal of the AND circuit 35 is connected to the microcomputer 21. The other input terminal of the AND circuit 35 is connected to the output terminal of the inverter 40.

[0063] The connection node between the current output circuit 31 and the variable resistor 36 is also connected to the filter circuit 41. The filter circuit 41 is also connected to the waveform value detection unit 42. The waveform value detection unit 42 is connected to the microcomputer 21.

[0064] A resistance voltage is applied to one end of the voltage-dividing resistor 44. The voltage value of the resistance voltage, i.e., the resistance voltage value Vcc, is a certain value, for example, 5V. The other end of the voltage-dividing resistor 44 is connected to one end of a detection switch 45. The other end of the detection switch 45 is connected to a connection node between the microcomputer 21 and the current output circuit 31 and the inner connector B2. The microcomputer 21 is also connected to an adjustment unit 43, a switching unit 46, and a temperature estimation unit 47. The connection node between the microcomputer 21 and the adjustment unit 43 is connected to the waveform value detection unit 42.

[0065] Regarding the power switch 30, when the voltage value of the gate based on the potential of the source is greater than a certain voltage value, current can flow through the drain and the source. In this case, the power switch 30 is turned on. Regarding the power switch 30, when the voltage value of the gate based on the potential of the source is less than a certain voltage value, current does not flow through the drain and the source. In this case, the power switch 30 is turned off.

[0066] The microcomputer 21 outputs a high-level voltage, a low-level voltage, or a PWM signal to the AND circuit 35. The inverter 40 outputs a high-level voltage or a low-level voltage to the AND circuit 35.

[0067] When the inverter 40 outputs a high-level voltage, when the microcomputer 21 outputs a high-level voltage to the AND circuit 35, the AND circuit 35 outputs the high-level voltage to the drive circuit 34. In the same case, when the microcomputer 21 outputs a low-level voltage to the AND circuit 35, the AND circuit 35 outputs the low-level voltage to the drive circuit 34. In the same case, when the microcomputer 21 outputs a PWM signal to the AND circuit 35, the AND circuit 35 outputs the voltage indicated by the PWM signal to the drive circuit 34.

[0068] When the voltage outputted by the AND circuit 35 is switched from a low-level voltage to a high-level voltage, the driving circuit 34 increases the gate voltage value with respect to the ground potential in the power switch 30. As a result, the gate voltage value with respect to the source potential in the power switch 30 becomes equal to or higher than a certain voltage value, and the power switch 30 is switched on.

[0069] When the voltage outputted by the AND circuit 35 is switched from a high-level voltage to a low-level voltage, the driving circuit 34 in the power switch 30 lowers the voltage value of the gate with respect to the ground potential. As a result, in the power switch 30, the voltage value of the gate with respect to the potential of the source is less than a certain voltage value, and the power switch 30 is switched off. The driving circuit 34 functions as a switching unit.

[0070] When the drive circuit 34 switches the power switch 30 to on, current flows from the positive electrode of the battery 10 in the order of the outer connector A1, the inner connector B1, the power switch 30, the current output circuit 31, the inner connector B2, the outer connector A2, the load 11, the outer connector A3, and the inner connector B3, and power is supplied to the load 11. Therefore, the inner connectors B2 and B3 are arranged in the current path of the current flowing through the power switch 30. When the drive circuit 34 switches the power switch 30 to off, the power supply from the battery 10 to the load 11 is stopped.

[0071] The load 11 is assumed to be an inductive load having a coil. In this case, while power is supplied from the battery 10 to the load 11, energy is stored in the coil of the load 11. When the power switch 30 is switched off, current flows from one end of the load 11 on the external connector A3 side in the order of the return diode 33, the current output circuit 31, and the load 11, and the coil of the load 11 releases energy.

[0072] While the load 11 releases energy, the current value of the current flowing through the freewheeling diode 33 decreases at a certain slope. The freewheeling diode 33 is a diode for releasing the energy of the load 11. When the load 11 is not an inductive load, the current does not flow through the freewheeling diode 33.

[0073] Hereinafter, the voltage value of the positive electrode of the battery 10 based on the ground potential is recorded as the battery voltage value, and the current value of the current flowing to the load 11 through the wire W is recorded as the load current value. The battery voltage value is the voltage value of the voltage applied to the load 11 when the power switch 30 is turned on when the load 11 is connected to the inner connectors B2 and B3.

[0074] The voltage detection circuit 32 detects the battery voltage value. The voltage detection circuit 32 outputs the detected analog voltage information indicating the battery voltage value to the microcomputer 21. For example, the voltage detection circuit 32 has two resistors. In this case, the two resistors divide the voltage of the battery 10 and output the voltage value of the divided voltage to the microcomputer 21 as voltage information.

[0075] The current output circuit 31 is formed by using, for example, a current mirror circuit, and outputs a current to the variable resistor 36. The current value of the current output from the current output circuit 31 to the variable resistor 36 is a value calculated by dividing the load current value by a prescribed number. The load current value, the prescribed number, and the variable resistance value of the variable resistor 36 are denoted as Ic, N, and Rv, respectively. The voltage value between both ends of the variable resistor 36 is represented by Ic·Rv / N. “·” represents multiplication. Hereinafter, the voltage value between both ends of the variable resistor 36 is denoted as the both-end voltage value.

[0076] The voltage value of the positive electrode of the DC power supply 38 with the ground potential as a reference, that is, the power supply voltage value, is denoted as Vd. The comparator 37 compares the power supply voltage value Vd with the both-end voltage value Vb (=Ic·Rv / N) of the variable resistor 36. When Ic·Rv / N < Vd is satisfied, that is, when Ic < N·Vd / Rv is satisfied, the comparator 37 outputs a low-level voltage to the latch circuit 39.

[0077] When Ic·Rv / N ≥ Vd is satisfied, that is, when Ic ≥ N·Vd / Rv is satisfied, the comparator 37 outputs a high-level voltage to the latch circuit 39. The current threshold Ith of the load current value Ic is represented by N·Vd / Rv. The prescribed number N and the power supply voltage value Vd are constant values. Therefore, the current threshold Ith varies according to the variable resistance value Rv. The larger the variable resistance value Rv is, the smaller the current threshold Ith is.

[0078] The microcomputer 21 outputs a resistance value signal indicating the resistance value to the waveform value detection unit 42 and the adjustment unit 43. When the adjustment unit 43 is input with the resistance value signal from the microcomputer 21, the adjustment unit 43 adjusts the variable resistance value of the variable resistor to the resistance value indicated by the input resistance value signal. Therefore, the variable resistance value, that is, the current threshold, is adjusted by the microcomputer 21. The microcomputer 21 outputs a resistance value signal to notify the waveform value detection unit 42 of the variable resistance value.

[0079] During the period when the comparator 37 outputs a low-level voltage, that is, during the period when the load current value is less than the current threshold, the latch circuit 39 outputs a low-level voltage to the inverter 40. When the latch circuit 39 outputs a low-level voltage, the inverter 40 outputs a high-level voltage. As described above, when the inverter 40 outputs a high-level voltage, the AND circuit 35 outputs the voltage represented by the voltage or PWM signal output from the microcomputer 21 to the drive circuit 34, and the drive circuit 34 switches the power supply switch 30 to on or off according to the instruction of the microcomputer 21.

[0080] When the voltage output to the comparator 37 is switched from a low-level voltage to a high-level voltage, that is, when the load current value becomes equal to or greater than the current threshold, the latch circuit 39 switches the voltage output to the inverter 40 from a low-level voltage to a high-level voltage. As a result, the inverter 40 switches the voltage output to the AND circuit 35 from a high-level voltage to a low-level voltage. When the voltage output from the inverter 40 is switched from a high-level voltage to a low-level voltage, the voltage output from the AND circuit 35 is switched from a high-level voltage to a low-level voltage, and the drive circuit 34 switches the power supply switch 30 to OFF regardless of the output from the microcomputer 21 to the AND circuit 35.

[0081] After switching the voltage output to the inverter 40 to a high level voltage, the latch circuit 39 continues to output a high level voltage to the inverter 40 regardless of the voltage output from the comparator 37. Therefore, after the load current value becomes equal to or greater than the current threshold, the drive circuit 34 keeps the power switch 30 off.

[0082] The voltage value across the variable resistor 36 is input to the filter circuit 41. The filter circuit 41 removes noise from the analog voltage value across the input. The filter circuit 41 outputs the analog voltage value across the input from which the noise is removed to the waveform value detection unit 42. The filter circuit 41 is configured using, for example, a resistor and a capacitor. The waveform value detection unit 42 periodically converts the analog voltage value across the input into a digital voltage value across the input, and obtains the converted digital voltage value across the input.

[0083] The voltage value Vb across the terminals is represented by Ic·Rv / N, and thus the load current value Ic is represented by N·Vb / Rv. As described above, the variable resistance value Rv is notified from the microcomputer 21 to the waveform value detection unit 42. The waveform value detection unit 42 detects a plurality of waveform values ​​related to the current waveform drawn by the load current value Ic based on the plurality of voltage values ​​Vb across the terminals, i.e., the plurality of load current values ​​Ic, which are periodically acquired, and notifies the microcomputer 21 of the plurality of detected waveform values.

[0084] Figure 3 It is an explanatory diagram of multiple waveform values. Figure 3 The figure shows the transition related to the on and off of the power switch 30 and the transition of the load current value. The horizontal axis of the above transition represents time. The load 11 has a resistance component. Therefore, when the current flows to the load 11, the temperature of the load 11 rises, and when the power supply to the load 11 is stopped, the temperature of the load 11 drops. It is assumed that the temperature of the load 11 is low. When the power switch 30 is switched from off to on, as shown in FIG. Figure 3 As shown in FIG. 1 , the load current value rises rapidly from 0 (zero) A and then drops rapidly. The current whose value rises rapidly and then drops rapidly is the inrush current. The rising speed of the load current value related to the inrush current is a waveform value.

[0085] The peak value of the load current value related to the inrush current is the inrush current value. The time constant of the inrush current is the time from when the power switch 30 is switched from off to on until the load current value reaches (1-(1 / e)) (=0.632) times (e: natural logarithm) the inrush current value.

[0086] The load current value stabilizes over time. The average value of the stable load current value is the stable current value. The load current value vibrates slightly. The amplitude of this vibration is the pulsating current value. The period associated with this vibration is the pulsating current period. The impulse current value, the time constant of the impulse current, the stable current value, the pulsating current value, and the pulsating current period are also one waveform value.

[0087] When the load 11 is an inductive load, when the power switch 30 is switched from on to off, the load 11 releases energy, and the current flows to the load 11 via the return diode 33. During the period when the load 11 releases energy, the load current value decreases to 0 (zero) A with a certain slope. The time from when the power switch 30 is switched off to when the load current value reaches 0 (zero) A is the return time. The return time is also a waveform value. When the load 11 is not an inductive load, the return time is 0 seconds. The number of times the inrush current is generated, that is, the number of inrush currents, is also a waveform value.

[0088] The waveform value detection unit 42 outputs the steady current value, the surge current value, the time constant of the surge current, the number of surge currents, the rising speed of the surge current, the pulsating current value, the pulsating current cycle and the return time as a plurality of waveform values ​​to the microcomputer 21. These values ​​are digital values. The waveform value detection unit 42 also outputs the digital load current value to the microcomputer 21.

[0089] The on signal indicating the detection switch 45 is switched to the on state and the off signal indicating the detection switch 45 is switched to the off state are transmitted from the microcomputer 21 to the Figure 2 The switch unit 46 shown in FIG. 4 is input. When an on signal is input, the switch unit 46 switches the detection switch 45 to on, and when an off signal is input, the detection switch 45 is switched to off. Therefore, the switch unit 46 switches the detection switch 45 to on or off according to the instruction of the microcomputer 21.

[0090] The voltage value of the inner connector B2 based on the ground potential is input to the microcomputer 21. Hereinafter, the voltage value of the inner connector B2 based on the ground potential is recorded as the connector voltage value. The simulated connector voltage value is input to the microcomputer 21. The microcomputer 21 detects the connection of the load 11 to the inner connectors B2 and B3 based on the connector voltage values ​​when the power switch 30 and the detection switch 45 are respectively turned off and turned on. The resistance value of the voltage-dividing resistor 44 is sufficiently larger than the resistance value of the load 11 that is likely to be connected to the inner connectors B2 and B3.

[0091] When the power switch 30 and the detection switch 45 are respectively disconnected and connected, when the load 11 is connected, the current flows in the order of the voltage divider resistor 44 and the load 11, and the resistor voltage applied to one end of the voltage divider resistor 44 is divided by the voltage divider resistor 44 and the load 11. As a result, the connector voltage value is sufficiently lower than the resistor voltage value Vcc and is lower than the reference voltage value. The reference voltage value is a certain value and is set in advance. When the power switch 30 and the detection switch 45 are respectively disconnected and connected, when the connection of the load 11 is disconnected, the current does not flow to the voltage divider resistor 44. Therefore, the connector voltage value is substantially consistent with the resistor voltage value Vcc and is higher than the reference voltage value.

[0092] It should be noted that when the power switch 30 and the detection switch 45 are respectively turned off and on, when the load 11 is connected, a voltage is applied to the load 11. However, the voltage value of the voltage applied to the load 11 is sufficiently low, so the load 11 does not operate.

[0093] The temperature estimating unit 47 estimates the ambient temperature of the load 11, that is, the ambient temperature, and outputs simulated temperature information indicating the estimated ambient temperature to the microcomputer 21. The temperature estimating unit 47 outputs, for example, a simulated voltage value corresponding to the estimated ambient temperature as the simulated temperature information to the microcomputer 21. The ambient temperature estimated by the temperature estimating unit 47 is the ambient temperature in the vehicle, and corresponds not only to the ambient temperature of the load 11 but also to the ambient temperature of the electric wire W, for example.

[0094] Figure 4 1 is a block diagram showing the main structure of the microcomputer 21. The microcomputer 21 includes input units 50, 51, 52, 53, output units 54, 55, 56, A / D converters 57, 58, 59, a timer 60, a storage unit 61, and a control unit 62. The input units 50, 51, 52 are connected to the A / D converters 57, 58, 59, respectively. The input unit 53, the output units 54, 55, 56, the A / D converters 57, 58, 59, the timer 60, the storage unit 61, and the control unit 62 are connected to the internal bus 63.

[0095] The input unit 50 is also connected to the voltage detection circuit 32. The input unit 51 is also connected to the middle of the electric wire W. The input unit 52 is also connected to the temperature estimation unit 47. The input unit 53 is also connected to the waveform value detection unit 42. The output unit 54 is also connected to one input end of the AND circuit 35. The output unit 55 is also connected to the waveform value detection unit 42 and the adjustment unit 43. The output unit 56 is also connected to the switching unit 46.

[0096] The analog voltage information is input from the voltage detection circuit 32 to the input unit 50. The input unit 50 outputs the analog voltage information input from the voltage detection circuit 32 to the A / D conversion unit 57. The A / D conversion unit 57 converts the analog voltage information input from the input unit 50 into digital voltage information. The control unit 62 obtains the digital voltage information from the A / D conversion unit 57.

[0097] The output unit 54 outputs a high-level voltage, a low-level voltage, or a PWM signal to the AND circuit 35 according to the instruction of the control unit 62. The control unit 62 also instructs the output unit 54 on the duty ratio of the PWM signal.

[0098] The waveform value detection unit 42 outputs the steady current value, the surge current value, the time constant of the surge current, the number of surge currents, the rising speed of the surge current, the pulsating current value, the pulsating current cycle, and the return time as a plurality of waveform values ​​to the input unit 53. The control unit 62 obtains these waveform values ​​from the input unit 53. The waveform value detection unit 42 also outputs the load current value to the input unit 53, and the control unit 62 obtains the load current value from the input unit 53.

[0099] The output unit 55 outputs a resistance value signal indicating the resistance value to the waveform value detection unit 42 and the adjustment unit 43 according to the instruction of the control unit 62. Thus, the adjustment unit 43 adjusts the variable resistance value of the variable resistor 36 to the resistance value of the resistance value signal and notifies the waveform value detection unit 42 of the variable resistance value.

[0100] The output unit 56 outputs an on signal and an off signal to the switching unit 46 according to the instruction of the control unit 62. As described above, the switching unit 46 switches the detection switch 45 on when the on signal is input, and switches the detection switch 45 off when the off signal is input.

[0101] The analog connector voltage value is input to the input unit 51. The input unit 51 outputs the input analog connector voltage value to the A / D converter 58. The A / D converter 58 converts the analog connector voltage value input from the input unit 51 into a digital connector voltage value. The control unit 62 obtains the digital connector voltage value from the A / D converter 58.

[0102] The analog temperature information is input from the temperature estimation unit 47 to the input unit 52. The input unit 52 outputs the analog temperature information input from the temperature estimation unit 47 to the A / D conversion unit 59. The A / D conversion unit 57 converts the analog temperature information input from the input unit 52 into digital temperature information. The control unit 62 obtains the digital temperature information from the A / D conversion unit 59.

[0103] The timer 60 starts and stops timing according to the instruction of the control unit 62. The timing time measured by the timer 60 is read from the timer 60 by the control unit 62.

[0104] The storage unit 61 is a nonvolatile memory and stores a computer program 70 , a power supply control table 71 , and a waveform value table 72 .

[0105] The control unit 62 has a processing element that executes processing. The processing element is, for example, a CPU (Central Processing Unit). The processing element of the control unit 62 executes a power supply control process for controlling the power supply to the load 11, a wire protection process for protecting the wire W from abnormal temperature, and a connection detection process for detecting the connection of the load 11 to the inner connectors B2 and B3 by executing a computer program 70. The computer program 70 is used to make the processing element (computer) of the control unit 62 execute the power supply control process, the wire protection process, and the connection detection process.

[0106] It should be noted that the number of processing elements included in the control unit 62 may be two or more. In this case, the plurality of processing elements may cooperate to respectively execute the power supply control process, the wire protection process, and the connection detection process.

[0107] In addition, the computer program 70 may be stored in the storage medium E in a manner that can be read by the processing element of the control unit 62. In this case, the computer program 70 read from the storage medium E by a reading device not shown is stored in the storage unit 61. The storage medium E is an optical disk, a floppy disk, a magnetic disk, a magneto-optical disk, or a semiconductor memory, etc. The optical disk is a CD (Compact Disc)-ROM (Read Only Memory), a DVD (Digital Versatile Disc)-ROM, or a BD (Blu-ray (registered trademark) Disc), etc. The magnetic disk is, for example, a hard disk. In addition, the computer program 70 may be downloaded from an external device not shown connected to a communication network not shown, and the downloaded computer program 70 may be stored in the storage unit 61.

[0108] Figure 5 : is a table showing the power supply control table 71. The power supply control table 71 includes a power supply flag field, a connection flag field, a type field, a variable resistance value field, a current threshold field, a PWM flag field, a duty ratio field, a prohibition flag field, a previous temperature difference field, and a temperature threshold field.

[0109] The power supply flag field stores the value of the power supply flag. The value of the power supply flag is set to 0 or 1 by the control unit 62. When the value of the power supply flag is 0, it means that the power supply switch 30 is off and power is not supplied to the load 11. When the value of the power supply flag is 1, it means that the power supply switch 30 is on and power is supplied to the load 11.

[0110] The connection flag field stores the value of the connection flag. The value of the connection flag is set to 0 or 1 by the control unit 62. When the value of the connection flag is 0, it means that the load 11 is not connected to the inner connectors B2 and B3. When the value of the connection flag is 1, it means that the load 11 is connected to the inner connectors B2 and B3.

[0111] The type field stores the type of the load 11 . Examples of the type of the load 11 include a valve, a brush-equipped motor, and an electromagnetic clutch. The type of the load 11 is updated by the control unit 62 .

[0112] The variable resistance value field stores the variable resistance value of the variable resistor 36. The variable resistance value stored in the variable resistance value field is updated by the control unit 62.

[0113] The current threshold is stored in the current threshold field. The current threshold stored in the current threshold field is updated by the control unit 62. As described above, the current threshold Ith is represented by N·Vd / Rv. N, Vd, and Rv are a specified number, a power supply voltage value, and a variable resistance value, respectively. The specified number N and the power supply voltage value Vd are constants, so the determination of the current threshold Ith is equivalent to the determination of the variable resistance value Rv.

[0114] The PWM flag field stores the value of the PWM flag. The value of the PWM flag is set to 0 or 1 by the control unit 62. When the value of the PWM flag is 0, PWM control is not performed for the turning on and off of the power switch 30. When the value of the PWM flag is 1, PWM control is performed for the turning on and off of the power switch 30.

[0115] The duty ratio field stores the value of the duty ratio of the PWM signal. The value of the duty ratio is updated by the control unit 62.

[0116] The prohibition flag field stores the prohibition flag value. The prohibition flag value is set to 0 or 1 by the control unit 62. When the prohibition flag value is 0, power supply via the wire W is permitted. When the prohibition flag value is 1, power supply via the wire W is prohibited.

[0117] The control unit 62 repeatedly performs the wire protection process. In the wire protection process, the control unit 62 repeatedly calculates the temperature difference between the ambient temperature and the temperature of the wire W. Hereinafter, the temperature of the wire W is described as the wire temperature. The previous temperature difference field stores the temperature difference previously calculated by the control unit 62. The previous temperature difference is updated by the control unit 62.

[0118] The temperature threshold field stores a temperature threshold related to the electric wire protection. In the electric wire protection process, the electric wire temperature is prevented from exceeding the temperature threshold.

[0119] Figure 6The control unit 62 corrects each waveform value input from the waveform value detection unit 42 to the input unit 53 in the connection detection process to a waveform value when the battery voltage value is a predetermined voltage value and the ambient temperature is a predetermined temperature. The predetermined voltage value is, for example, 12V.

[0120] The waveform value table includes a battery voltage value field, an ambient temperature field, a stable current value field, an impact current value field, a time constant field, an impact current number field, a rising speed field, a pulsating current value field, a pulsating current cycle field and a return time field.

[0121] The battery voltage value field stores the battery voltage value. The battery voltage value in the battery voltage value field is updated by the control unit 62. As described above, the control unit 62 obtains the voltage information indicating the battery voltage value from the A / D converter 57.

[0122] The ambient temperature field stores the ambient temperature. The ambient temperature in the ambient temperature field is updated by the control unit 62. As described above, the control unit 62 obtains temperature information indicating the ambient temperature from the A / D conversion unit 57.

[0123] The stable current value, the impulse current value, the time constant, the impulse current number, the rising speed, the pulsating current value, the pulsating current cycle, and the return time field are respectively stored with the stable current value before and after correction, the impulse current value, the time constant, the impulse current number, the rising speed, the pulsating current value, the pulsating current cycle, and the return time field. The values ​​of these fields before and after correction are updated by the control unit 62.

[0124] Figure 7 6 is a flowchart showing the order of the power supply control process. The control unit 62 periodically performs the power supply control process. In the description of the power supply control process, the inverter 40 outputs a high-level voltage, that is, it is assumed that the load current value is less than the current threshold. When the inverter 40 outputs a low-level voltage, the drive circuit 34 maintains the power supply switch 30 in the off state regardless of the output of the output unit 54.

[0125] The control unit 62 determines whether the value of the prohibition flag of the power supply control table 71 is 0 (step S1). If the control unit 62 determines that the value of the prohibition flag is 0, that is, power supply through the power line W is permitted (S1: Yes), it determines whether the value of the connection flag is 1 (step S2).

[0126] The control unit 62 terminates the power supply control process when it is determined that the value of the prohibition flag is not 0, that is, the value of the prohibition flag is 1 (S1: No), or when it is determined that the value of the connection flag is not 1, that is, the value of the connection flag is 0 (S2: No). As described above, the case where the value of the prohibition flag is 1 means that power supply via the electric wire W is prohibited. The case where the value of the connection flag is 0 means that the load 11 is not connected to the inner connectors B2 and B3.

[0127] When the control unit 62 determines that the value of the connection flag is 1, that is, the load 11 is connected to the inner connectors B2 and B3 (S2: Yes), it determines whether to start power supply to the load 11 (step S3). In step S3, the control unit 62 determines that power supply is started when, for example, a start signal instructing the start of power supply is input to an input unit (not shown), and determines that power supply is not started when the start signal is not input to the input unit.

[0128] When the control unit 62 determines that the power supply is not to be started (S3: No), it determines whether to end the power supply to the load 11 (step S4). In step S4, the control unit 62 determines that the power supply is to be ended when, for example, an end signal indicating the end of the power supply is input to an input unit (not shown), and determines that the power supply is not to be ended when the end signal is not input to the input unit. When the control unit 62 determines that the power supply is not to be ended (S4: No), the power supply control process is ended.

[0129] When the control unit 62 determines that the power supply is to be terminated (S4: Yes), it sets the value of the power supply flag of the power supply control table 71 to 0 (step S5), and instructs the output unit 54 to output a low-level voltage to the AND circuit 35 (step S6). As a result, the AND circuit 35 outputs a low-level voltage to the drive circuit 34, and the drive circuit 34 switches the power supply switch 30 to the off state. Instructing the output unit 54 to output a low-level voltage is equivalent to instructing the drive circuit 34 to switch the power supply switch 30 to the on state. After executing step S6, the control unit 62 terminates the power supply control process.

[0130] When the control unit 62 determines that power supply has started (S3: Yes), it sets the value of the power supply flag of the power supply control table 71 to 1 (step S7), and instructs the output unit 55 to output a resistance value signal having a resistance value equal to the variable resistance value of the power supply control table 71 (step S8). As a result, the adjustment unit 43 adjusts the variable resistance value of the variable resistor 36 to the variable resistance value indicated by the power supply control table 71. As a result, the current threshold is changed to the current threshold value indicated by the power supply control table 71. As described above, the variable resistance value of the power supply control table 71 is notified to the waveform value detection unit 42.

[0131] After executing step S8, the control unit 62 determines whether the value of the PWM flag of the power supply control table 71 is 0 (step S9). When the control unit 62 determines that the value of the PWM flag is 0, that is, PWM control is not performed (S9: Yes), it instructs the output unit 54 to output a high-level voltage to the AND circuit 35 (step S10). As a result, the AND circuit 35 switches the voltage output to the drive circuit 34 to a high-level voltage, and the drive circuit 34 switches the power supply switch 30 to on. As a result, power is supplied to the load 11. Instructing the output unit 54 to output a high-level voltage is equivalent to instructing the drive circuit 34 to switch the power supply switch 30 to on.

[0132] When the control unit 62 determines that the value of the PWM flag is not 0, that is, the value of the PWM flag is 1 (S9: No), it instructs the output unit 54 to output the PWM signal to the AND circuit 35 (step S11). As a result, the AND circuit 35 outputs the voltage represented by the PWM signal to the drive circuit 34, and the drive circuit 34 alternately switches the power supply switch 30 to on and off according to the voltage represented by the PWM signal. As a result, power is supplied to the load 11. The duty ratio of the PWM signal is adjusted to the duty ratio stored in the power supply control table 71.

[0133] Instructing output unit 54 to output a PWM signal corresponds to alternately instructing drive circuit 34 to switch power switch 30 between on and off. As described above, when the value of the PWM flag is 1, PWM control is performed.

[0134] After executing one of steps S10 and S11 , the control unit 62 ends the power supply control process.

[0135] As described above, in the power supply control process, the control unit 62 of the microcomputer 21 performs power supply control corresponding to the power supply control conditions shown in the power supply control table 71. The power supply control conditions are conditions related to the power supply control to the load 11, and specifically include the variable resistance value (current threshold), the value of the PWM flag, and the duty cycle of the PWM signal. The power supply control conditions are appropriately changed in the connection detection process.

[0136] Figure 8 2 is a flowchart showing the sequence of the electric wire protection process. The control unit 62 periodically performs the electric wire protection process. In the electric wire protection process, the control unit 62 first obtains the load current value from the input unit 53 (step S21) and obtains the temperature information from the A / D conversion unit 57 (step S22). Next, the control unit 62 reads the previous temperature difference stored in the power supply control table 71 (step S23).

[0137] Next, the control unit 62 calculates the temperature difference between the wire temperature of the wire W and the ambient temperature in the vehicle based on the load current value obtained in step S21, the ambient temperature indicated by the temperature information obtained in step S22, and the previous temperature difference read in step S23 (step S24). The previous temperature difference read in step S23 is the temperature difference calculated by the previous wire protection process. Next, the control unit 62 calculates the wire temperature by adding the temperature difference calculated in step S24 to the ambient temperature obtained in step S22 (step S25).

[0138] Next, the control unit 62 determines whether the electric wire temperature calculated in step S25 is equal to or higher than the temperature threshold value of the power supply control table 71 (step S26). When the control unit 62 determines that the electric wire temperature is equal to or higher than the temperature threshold value (S26: Yes), it sets the value of the prohibition flag to 1 (step S27), sets the value of the power supply flag to 0 (step S28), and instructs the output unit 54 to output a low-level voltage to the AND circuit 35 (step S29).

[0139] As a result, the AND circuit 35 switches the voltage output to the drive circuit 34 to a low-level voltage, and the drive circuit 34 switches the power switch 30 to OFF. As a result, the power supply to the load 11 is stopped. After the drive circuit 34 switches the power switch 30 to OFF, the value of the prohibition flag is set to 1, so the power switch 30 is not switched to ON in the power supply control process.

[0140] When the control unit 62 determines that the electric wire temperature is lower than the temperature threshold value (S26: No) or after executing step S29, the control unit 62 updates the previous temperature difference of the power supply control table 71 to the temperature difference calculated in step S24 (step S30) and ends the electric wire protection process.

[0141] As described above, when the electric wire temperature becomes equal to or higher than the temperature threshold, the drive circuit 34 switches the power switch 30 to OFF and maintains the OFF state of the power switch 30. Therefore, the electric wire temperature does not exceed the temperature threshold.

[0142] It should be noted that the previous temperature difference may be any temperature difference calculated previously, and is not limited to the temperature difference calculated by the previous electric wire protection process. The previous temperature difference may also be the temperature difference calculated by the previous electric wire protection process.

[0143] Fig. 9is a flowchart showing the order of the connection detection process. The control unit 62 periodically performs the connection detection process. The control unit 62 determines whether the value of the prohibition flag of the power supply control table 71 is 0 (step S41). When the control unit 62 determines that the value of the prohibition flag is 0, that is, the power supply to the load 11 is allowed (S41: Yes), it determines whether the value of the power supply flag is 0 (step S42).

[0144] The control unit 62 terminates the connection detection process when it is determined that the value of the prohibition flag is not 0, that is, the value of the prohibition flag is 1 (S41: No), or when it is determined that the value of the power supply flag is not 0, that is, the value of the power supply flag is 1 (S42: No). Therefore, when the power supply to the load 11 is prohibited or the power supply switch 30 is turned on, the connection detection process is terminated.

[0145] When the control unit 62 determines that the value of the power supply flag is 0, that is, the power supply switch 30 is off (S42: Yes), it instructs the output unit 55 to output an on signal to the switching unit 46 (step S43). As a result, the switching unit 46 switches the detection switch 45 to on, and outputs the voltage value of the voltage divided by the voltage-dividing resistor 44 and the load 11 as an analog connector voltage value to the input unit 51. The analog connector voltage value input to the input unit 51 is converted into a digital connector voltage value by the A / D conversion unit 58.

[0146] After executing step S43, the control unit 62 obtains the connector voltage value from the A / D converter 58 (step S44), and instructs the output unit 56 to output an OFF signal to the switch unit 46 (step S45). As a result, the switch unit 46 switches the detection switch 45 to OFF.

[0147] Next, the control unit 62 determines whether the load 11 is connected to the inner connectors B2 and B3 based on the connector voltage value obtained in step S44 (step S46). In step S46, the control unit 62 determines that the load 11 is connected when the connector voltage value is less than the reference voltage value. The control unit 62 determines that the load 11 is not connected when the connector voltage value is greater than the reference voltage value. The control unit 62 detects the connection of the load 11 to the inner connectors B2 and B3 by executing step S46. The control unit 62 functions as a connection detection unit.

[0148] When the control unit 62 determines that the load 11 is not connected (S46: No), it determines whether the value of the connection flag of the power supply control table 71 is 1 (step S47). Here, the value of the connection flag is 1 when the load 11 is connected at the time when the previous connection detection process is completed.

[0149] When the control unit 62 determines that the value of the connection flag is not 1, that is, the value of the connection flag is 0 (S47: No), the connection detection process ends. When the control unit 62 determines that the value of the connection flag is 1 (S47: Yes), the connection flag value is set to 0 (step S48), and the connection detection process ends.

[0150] When the control unit 62 determines that the load 11 is connected, that is, when the connection of the load 11 is detected (S46: Yes), it determines whether the value of the connection flag of the power supply control table 71 is 0 (step S49). Here, the case where the value of the connection flag is 0 means that the load 11 was not connected at the time when the previous connection detection process was completed.

[0151] When the control unit 62 determines that the value of the connection flag is not 0, that is, the value of the connection flag is 1 (S49: No), the connection detection process is terminated. When the control unit 62 determines that the value of the connection flag is 0 (S49: Yes), the value of the connection flag is set to 1 (step S50), and the update process of updating the plurality of waveform values ​​stored in the waveform value table 72 is executed (step S51), and the connection detection process is terminated.

[0152] Fig.10 and Fig.11 1 is a flowchart showing the order of the update process. In the description of the update process, the inverter 40 outputs a high-level voltage, that is, it is assumed that the load current value is less than the current threshold. As described above, when the inverter 40 outputs a low-level voltage, the drive circuit 34 maintains the power switch 30 in the off state regardless of the output of the output unit 54.

[0153] In the updating process, the control unit 62 first instructs the output unit 54 to output a high level voltage to the AND circuit 35 (step S61). As a result, the AND circuit 35 outputs a high level voltage to the drive circuit 34, and the drive circuit 34 switches the power switch 30 from off to on, so that current flows from the battery 10 to the load 11.

[0154] Next, the control unit 62 instructs the timer 60 to start timing (step S62), and determines whether the time counted by the timer 60 is greater than the on-time (step S63). The on-time is a certain value and is set in advance. When the control unit 62 determines that the counted time is less than the on-time (S63: No), the control unit 62 executes step S63 again and waits until the counted time becomes greater than the on-time. When the control unit 62 determines that the counted time is greater than the on-time (S63: Yes), the control unit 62 instructs the timer 60 to end timing (step S64).

[0155] Next, the control unit 62 instructs the output unit 54 to output a low voltage to the AND circuit 35 (step S65). As a result, the AND circuit 35 outputs a low voltage to the drive circuit 34, and the drive circuit 34 switches the power switch 30 from on to off, stopping the power supply from the battery 10 to the load 11.

[0156] Next, the control unit 62 instructs the timer 60 to start timing again (step S66), and determines whether the timing time of the timer 60 is longer than the disconnection time (step S67). The disconnection time is also a certain value and is set in advance. When the control unit 62 determines that the timing time is less than the disconnection time (S67: No), the control unit 62 executes step S67 again and waits until the timing time becomes longer than the disconnection time. When the control unit 62 determines that the timing time is longer than the disconnection time (S67: Yes), the control unit 62 instructs the timer 60 to end timing (step S68).

[0157] As described above, the power switch 30 is kept on from the start of the update process until the on time has passed, and then the power switch 30 is kept off until the off time has passed. Figure 3 As described above, the waveform value detection unit 42 detects a plurality of waveform values ​​and outputs the detected plurality of waveform values ​​to the input unit 53 .

[0158] After executing step S68, the control unit 62 obtains a plurality of waveform values ​​from the input unit 53 (step S69). The plurality of waveform values ​​obtained by step S69 are a steady current value, an inrush current value, a time constant of the inrush current, the number of inrush currents, a rising speed of the inrush current, a pulsating current value, a pulsating current cycle, and a return time. Next, the control unit 62 obtains voltage information from the A / D converter 57 (step S70), and obtains temperature information from the A / D converter 59 (step S71). Next, the control unit 62 updates the plurality of waveform values ​​before correction, the battery voltage value, and the ambient temperature of the power supply control table 71 (step S72).

[0159] Specifically, the control unit 62 updates the plurality of waveform values ​​before correction to the plurality of waveform values ​​obtained in step S69. The control unit 62 updates the battery voltage value of the power supply control table 71 to the battery voltage value indicated by the voltage information obtained in step S70, and updates the ambient temperature of the power supply control table 71 to the ambient temperature indicated by the temperature information obtained in step S71.

[0160] Next, the control unit 62 corrects the plurality of waveform values ​​before correction in the waveform value table 72 to the plurality of waveform values ​​when the battery voltage value is a predetermined voltage value and the ambient temperature is a predetermined temperature based on the battery voltage value and the ambient temperature stored in the waveform value table 72 (step S73). The control unit 62 also functions as a correction unit and a second correction unit. Next, the control unit 62 updates the plurality of waveform values ​​after correction in the waveform value table 72 to the plurality of waveform values ​​corrected in step S73 (step S74).

[0161] Next, the control unit 62 determines the type of the load 11 based on the corrected waveform values ​​in the waveform value table 72 (step S75). As an example, with respect to the multiple types related to the load 11, the multiple waveform values ​​corresponding to each type are pre-stored in the storage unit 61. In step S75, the control unit 62 calculates the correlation value with the corrected waveform values ​​involved in the waveform value table 72 for the multiple waveform values ​​corresponding to each type. The control unit 62 determines the type of the load 11 as the type with the highest similarity represented by the calculated correlation value among the aforementioned multiple types.

[0162] As another example, the type of load 11 is determined using a learning model that has learned the relationship between multiple waveform values ​​and the type of load 11. The learning model is composed of, for example, a neural network, and is composed of an input layer, multiple intermediate layers, and an output layer. The nodes of each layer are connected to the nodes of the adjacent layer. Using multiple teacher data containing waveform value data and type data, the learning model is preliminarily made to learn the relationship between multiple waveform values ​​and the type of load 11. In step S75, the control unit 62 inputs the waveform value data representing the corrected multiple waveform values ​​in the waveform value table 72 into the input layer of the learning model, and determines the type of load 11 based on the output value output from the output layer of the learning model. The output value of the output layer represents the probability of corresponding to the actual type of load 11 for each of the multiple types. The control unit 62 also functions as a determination unit.

[0163] Next, the type of the load 11 stored in the power supply control table 71 is updated to the type determined in step S75 (step S76).

[0164] Next, the control unit 62 determines the power supply control conditions (step S77) based on the types in the power supply control table 71 and the corrected waveform values ​​in the waveform value table 72. Specifically, the power supply control conditions include the variable resistance value, the current threshold, the value of the PWM flag, and the duty cycle of the PWM signal. The control unit 62 also functions as a determination unit.

[0165] For example, the storage unit 61 stores conditions related to power supply control in advance for each of a plurality of types of loads 11. In step S77, the control unit 62 determines the power supply control condition to be a condition corresponding to the type of load 11 determined in step S75.

[0166] As described above, the current threshold Ith and the variable resistance value Rv satisfy the relationship Ith=N·Vd / Rv. N and Vd are a predetermined number and a power supply voltage value, respectively, and are constant values. Determining the value of the PWM flag is equivalent to determining whether to perform PWM control on the on and off of the power switch 30.

[0167] Next, the control unit 62 updates the power supply control conditions of the power supply control table 71 to the power supply control conditions determined in step S77 (step S78). After executing step S78, the control unit 62 ends the update process and returns the process to the connection detection process. As described above, when the control unit 62 ends the update process, the connection detection process also ends.

[0168] As described above, in the connection detection process, the control unit 62 detects the connection when the load 11 is connected to the inner connectors B2 and B3, and performs the update process. In the update process, the control unit 62 causes the drive circuit 34 to switch the power switch 30 from off to on, and then causes the drive circuit 34 to switch the power switch 30 from on to off. Based on the multiple waveform values ​​thus obtained, the control unit 62 determines the power supply control conditions and updates the power supply control conditions of the power supply control table 71.

[0169] Therefore, when the load 11 connected to the inside connectors B2 and B3 is changed, the current waveform of the load current value changes, so the power supply control conditions of the power supply control table 71 are immediately updated. Therefore, the time required to change the power supply control conditions is short.

[0170] It should be noted that the multiple waveform values ​​used to determine the power supply control conditions, i.e., the multiple waveform values ​​stored in the waveform value table 72, are not limited to the stable current value, the impulse current value, the time constant of the impulse current, the number of impulse currents, the rising speed of the load current value, the pulsating current value, the pulsating current cycle, and the reflow time. Moreover, the multiple waveform values ​​do not need to include all of the stable current value, the impulse current value, the time constant of the impulse current, the number of impulse currents, the rising speed of the load current value, the pulsating current value, the pulsating current cycle, and the reflow time. In addition, the number of waveform values ​​is not limited to 7, and can be any one of 1 to 6 or more than 8.

[0171] In addition, the items included in the power supply control condition are not limited to the variable resistance value, the current threshold value, the value of the PWM flag, and the duty cycle. For example, a temperature threshold value may be included as an item of the power supply control condition. In addition, the control unit 62 of the microcomputer 21 may estimate the ambient temperature of the load 11, i.e., the environmental temperature, based on the values ​​of various parameters related to the load 11, instead of the temperature estimation unit 47.

[0172] In addition, when the waveform values ​​stored in the waveform value table 72 do not include a waveform value that depends on the ambient temperature, such as an inrush current value, correction based on the ambient temperature is not required. In addition, when the waveform values ​​stored in the waveform value table 72 do not include a waveform value that depends on the battery voltage value, correction based on the battery voltage value is not required.

[0173] In addition, the power switch 30 is not limited to an N-channel FET, and may be a P-channel FET, a bipolar transistor, a relay contact, or the like.

[0174] The disclosed embodiments are to be considered in all respects as illustrative rather than restrictive. The scope of the present invention is disclosed by the claims rather than the above-mentioned meaning, and is intended to include all modifications within the meaning and scope equivalent to the claims.

[0175] Description of symbols

[0176] 1 Power System

[0177] 10. Battery

[0178] 11 Load

[0179] 12 Power supply control device

[0180] 20 Control machine

[0181] 21 Microcomputer

[0182] 30 Power switch

[0183] 31 Current output circuit

[0184] 32 Voltage detection circuit

[0185] 33 Recirculation diode

[0186] 34. Driving circuit (switching section)

[0187] 35 AND circuit

[0188] 36 Variable resistor

[0189] 37 Comparator

[0190] 38 DC power supply

[0191] 39 Latch Circuit

[0192] 40 Inverter

[0193] 41 Filter circuit

[0194] 42 Waveform value detection unit

[0195] 43 Adjustment Department

[0196] 44 Voltage divider resistor

[0197] 45 Detection switch

[0198] 46 Switching Department

[0199] 47 Temperature estimation unit

[0200] 50, 51, 52, 53 Input section

[0201] 54, 55, 56 Output section

[0202] 57, 58, 59 conversion unit

[0203] 60 Timer

[0204] 61 Storage

[0205] 62 Control unit (determination unit, connection detection unit, correction unit, second correction unit, determination unit)

[0206] 63 Internal bus

[0207] 70 Computer Programs

[0208] 71 Power supply control table

[0209] 72 Waveform Value Table

[0210] A1, A2, A3 Outer connector

[0211] B1, B2, B3 inner connector

[0212] E Storage Media

[0213] W Wire.

Claims

1. A power supply control device for controlling power supply to a load via a switch, wherein: The power supply control device comprises: a switching unit, which switches the switch on or off; and a determination unit that determines a power supply control condition related to power supply control to the load based on a waveform value related to a current waveform of a current flowing to the load when the switching unit switches the switch from off to on, The switching unit keeps the switch on for a certain period of time and then keeps the switch off for a certain period of time. The determination unit determines the power supply control condition based on a waveform value of the current waveform from when the switch unit starts to be maintained on to when the switch unit ends to be maintained off.

2. The power supply control device according to claim 1, wherein: The power supply control device comprises: a connector disposed in a current path of the current flowing through the switch, the load being detachably connected to the connector; and a connection detection unit for detecting connection of the load to the connector, The switching unit switches the switch from off to on when the connection detecting unit detects the connection.

3. The power supply control device according to claim 1 or 2, wherein: The switching unit switches the switch to off when the current value of the current flowing to the load becomes equal to or greater than a current threshold value, The power supply control condition includes the current threshold.

4. The power supply control device according to claim 1 or 2, wherein: The power supply control device comprises: a voltage detection circuit for detecting a voltage value of a voltage applied to the load; and The correction unit corrects the waveform value based on the voltage value detected by the voltage detection circuit.

5. The power supply control device according to claim 1 or 2, wherein: The power supply control device comprises: a temperature estimating unit that estimates the ambient temperature of the load; and The second correction unit corrects the waveform value based on the ambient temperature estimated by the temperature estimation unit.

6. The power supply control device according to claim 1 or 2, wherein: The power supply control device includes a determination unit that determines the type of the load based on the waveform value. The decision unit determines the power supply control condition as a power supply control condition corresponding to the type determined by the determination unit.

7. A power supply control method, comprising the following steps: Toggle the switch on or off; acquiring a waveform value related to a current waveform of a current flowing to a load when the switch is switched from off to on; determining a power supply control condition related to power supply control to the load based on the acquired waveform value; Keep the switch turned on for a certain period of time; and After the switch is kept on for a certain period of time, the switch is kept off for a certain period of time. The waveform value is acquired from the start of maintaining the on state to the end of maintaining the off state.

8. A computer program for causing a computer to execute the following steps: Indicating the switching of the switch to on or off; acquiring a waveform value related to a current waveform of a current flowing to a load when the switch is switched from off to on; determining a power supply control condition related to power supply control to the load based on the acquired waveform value; Keep the switch turned on for a certain period of time; and After the switch is kept on for a certain period of time, the switch is kept off for a certain period of time. The waveform value is acquired from the start of maintaining the on state to the end of maintaining the off state.

Images