Power supply control device

Abstract

This technology provides cost-effective control over the power supply to heater devices. [Solution] The power supply control device 20 that controls the power supply to the heater device 12 includes an acquisition unit that acquires information indicating the current value of the power supplied to the heater device 12, a determination unit that determines the amount of heat generated by the heater device 12 based on the acquired information indicating the current value, and a control unit that controls the power supply to the heater device 12 according to the determination result of the determination unit.

Description

Technical Field

[0001] The present disclosure relates to a technology for controlling power supply to a heater device. Background Art

[0002] Patent Document 1 discloses an on-vehicle camera device comprising: a camera unit that captures an image through window glass; a heat conductive member in thermal contact with the window glass; a heater device fixed in contact with an outer surface of the heat conductive member and having an anti-fog function of removing dew condensation and fog adhering to a surface of the window glass at a front portion of the camera unit; and a temperature measuring element provided at a substantially central portion of the heater device, partially disposed in contact with the heat conductive member. This temperature measuring element detects a temperature state of the heater device to determine operation of the heater device. Prior Art Literature Patent Literature

[0003] Patent Document 1 Japanese Unexamined Patent Application Publication No. 2021-197609 Summary of the Invention Problems to be Solved by the Invention

[0004] In the technology disclosed in Patent Document 1, since the detection result of the temperature measuring element is used to determine operation of the heater device, costs are increased due to the temperature measuring element and its wiring.

[0005] An object of the present disclosure is to provide a technology for controlling power supply to a heater device while suppressing costs. Means for Solving the Problems

[0006] To solve the above problems, one aspect of the present invention is a power supply control device for controlling the supply of power to a heater device, comprising: an acquisition unit that acquires information indicating the current value of the power supplied to the heater device; a determination unit that determines the amount of heat generated by the heater device based on the acquired information indicating the current value; and a control unit that controls the power supply to the heater device according to the determination result of the determination unit. [Effects of the Invention]

[0007] According to this disclosure, a technology can be provided to control the power supply to a heater device while keeping costs down. [Brief explanation of the drawing]

[0008] [Figure 1] This diagram shows the functional configuration of the control system in the embodiment. [Figure 2] This diagram shows the functional configuration of the power supply control device in the embodiment. [Figure 3] This is a flowchart of the power supply control method in the embodiment. [Modes for carrying out the invention]

[0009] Figure 1 shows the functional configuration of control system 1 of the embodiment. In Figure 1, each element described as a functional block that performs various processes can be made up of circuit blocks, memory, and other LSIs in hardware terms, and implemented in software terms by programs loaded into memory, etc. Therefore, it will be understood by those skilled in the art that these functional blocks can be implemented in various ways by hardware alone, software alone, or a combination thereof, and are not limited to any one of these.

[0010] A vehicle equipped with control system 1 may perform autonomous driving control. Control system 1 comprises a control device 10 and a heater device 12. The heater device 12 is capable of heating the vehicle's windows. The vehicle's windows are translucent, such as the front windshield and rear window, and are made of glass.

[0011] The heater device 12 has a heating element, and this heating element has a temperature characteristic in which its resistance changes according to the temperature. The temperature characteristic of the heater device 12 is such that the resistance value increases as the temperature increases.

[0012] The control device 10 includes a power supply control device 20, a relay unit 22, a current sensor 24, a voltage sensor 26, and a power input unit 28. The power input unit 28 is connected to a power supply unit and receives power from the power supply unit.

[0013] The relay unit 22 is controlled to turn on and off by receiving signals from the power supply control device 20 to instruct it to turn on and off. When the relay unit 22 is turned on, the power input unit 28 and the heater device 12 are energized, and power is supplied from the power input unit 28 to the heater device 12. When the relay unit 22 is turned off, the power supply to the heater device 12 stops. The relay unit 22 also has a fuse function.

[0014] The current sensor 24 is installed between the relay unit 22 and the heater device 12 and detects the current value of the power supplied to the heater device 12. The current sensor 24 transmits information indicating the current value as the detection result to the power supply control device 20. The information indicating the current value may be the sensor value or a numerical value converted to a current value. The current sensor 24 is pre-installed as part of the relay unit 22.

[0015] The voltage sensor 26 is located on the input side of the relay unit 22 and is installed between the power input unit 28 and the power supply control device 20. The voltage sensor 26 detects the voltage value of the power supplied to the power supply control device 20 and detects the voltage value of the power supplied to the heater device 12 when the relay unit 22 is in the ON state. The voltage sensor 26 transmits information indicating the voltage value as a result of the detection to the power supply control device 20.

[0016] Figure 2 shows the functional configuration of the power supply control device 20 in the embodiment. The power supply control device 20 is an ECU (Electronic Control Unit) that controls the power supply to the heater device 12. The power supply control device 20 includes an acquisition unit 30, a temperature estimation unit 32, a heat generation amount estimation unit 34, a determination unit 36, and a control unit 38.

[0017] The acquisition unit 30 acquires information indicating the current value of the power supplied from the current sensor 24 to the heater device 12. The acquisition unit 30 also acquires information indicating the voltage value of the power supplied from the voltage sensor 26 to the heater device 12.

[0018] The temperature estimation unit 32 estimates the temperature of the heater device 12 based on information indicating the current value of the power supplied to the heater device 12. The temperature estimation unit 32 takes a current value as input and outputs the temperature of the heater device 12 based on data showing the relationship between the current value and temperature of the heater device 12, which is stored in advance. The data showing the relationship between the current value and the temperature of the heater device 12, which is stored in advance, is set by experiments or the like and may be a mathematical formula or a two-dimensional map.

[0019] The temperature estimation unit 32 may estimate the temperature of the heater device 12 based on the current and voltage values ​​of the power supplied to the heater device 12. The power input unit 28 receives the rated voltage from the power supply, but the voltage value supplied to the heater device 12 may change slightly due to temperature changes. Therefore, the temperature estimation unit 32 inputs the current and voltage values ​​based on data showing the relationship between the current, voltage, and temperature of the heater device 12, which is stored in advance, and outputs the temperature of the heater device 12. The data showing the relationship between the current, voltage, and temperature of the heater device 12, which is stored in advance, may be set by experimentation or the like, and may be a mathematical formula or a two-dimensional map.

[0020] The temperature estimation unit 32 may calculate the resistance value R of the heater device 12 based on the current value and voltage value of the power supplied to the heater device 12, and estimate the temperature T of the heater device 12 using the following formula (1) based on the calculated resistance value R. T = (R / R0 - 1) / a + T0 ... (1) T0 is a reference temperature, for example, 20°C. R0 is the resistance value of the heating wire of the heater device 12 at the reference temperature.

[0021] The determining unit 36 determines heat generation by the heater device 12, that is, energization of the heater device 12, based on the estimated temperature. The determining unit 36 determines to cause the heater device 12 to generate heat when the estimated temperature is equal to or lower than a predetermined threshold. The predetermined threshold is set through experiments or the like. By not using a temperature sensor that detects the temperature of the heater device 12, the number of sensors and wirings can be reduced, which enables cost reduction and weight reduction. Since the current sensor 24 provided in advance in the relay unit 22 is used, costs can be reduced. Note that, when determining energization of the heater device 12, the determining unit 36 may use the detection result of an outside air temperature sensor in addition to the estimated temperature. Of course, the determining unit 36 does not have to use the detection result of the outside air temperature sensor.

[0022] A heat generation amount estimating unit 34 estimates a heat generation amount based on information relating to electric power supplied to the heater device 12 acquired by an acquiring unit 30. The information relating to electric power supplied to the heater device 12 includes a current value, a voltage value, and an energization time of the electric power supplied to the heater device 12. The determining unit 36 determines to end heat generation of the heater device 12 based on the estimated heat generation amount. The determining unit 36 determines to end the heat generation when the estimated heat generation amount is equal to or greater than a set heat amount, and sends a determination result to a control unit 38. After the heater device 12 is energized, it takes time for the temperature to saturate. If the end of energization is determined based on temperature, depending on the saturation curve, the heater device 12 may continue to be energized even after defogging of a window is completed. Therefore, by ending energization of the heater device 12 based on the heat generation amount, power consumption can be suppressed.

[0023] The determining unit 36 may variably set the set heat amount for determining the energization end timing for the heater device 12 according to the estimated temperature. For example, the set heat amount is set to increase as the estimated temperature decreases. Accordingly, the control unit 38 can achieve anti-fogging with a smaller heat generation amount when the estimated temperature is not low, thereby suppressing power consumption.

[0024] The control unit 38 controls the power supply to the heater device 12 according to the decision result of the decision unit 36. The control unit 38 turns on the relay unit 22 when it receives a power supply start instruction from the decision unit 36, and turns off the relay unit 22 when it receives a power supply end instruction from the decision unit 36.

[0025] The control unit 38 controls the output to the heater device 12 using PWM (Pulse Width Modulation) control. When the heater device 12 generates heat, the control unit 38 sets the duty cycle according to the temperature estimated by the temperature estimation unit 32. If the estimated temperature is lower than the first temperature, the control unit 38 controls with a duty cycle that is larger than the duty cycle performed at the second temperature, which is higher than the first temperature. In other words, the control unit 38 increases the duty cycle when the estimated temperature is low and decreases the duty cycle when the estimated temperature is low. When the temperature of the heater device 12 rises and the resistance value increases, the duty cycle is lowered. This ensures a constant amount of heat is generated in the heater device 12 while smoothing the temperature rise, and allows for accurate determination of the timing of the end of power supply to the heater device 12.

[0026] The control unit 38 intermittently supplies power to the heater device 12 when the determination unit 36 ​​has not determined that the heater device 12 is generating heat, i.e., when the heater device 12 is not being energized. This allows the detection results of the current sensor 24 and voltage sensor 26 during energization to be obtained, and the temperature estimation unit 32 to estimate the temperature of the heater device 12. Furthermore, by supplying power intermittently, power consumption due to temperature estimation can be reduced. The period for intermittent power supply can be set, for example, from 1 minute to 30 minutes, and may be a fixed period or a variable period. The determination unit 36 ​​may determine the intermittent period.

[0027] The control unit 38, when power is not supplied to the heater device 12 and the estimated temperature is below a predetermined temperature, intermittently supplies power to the heater device 12 at shorter intervals than when the temperature is above the predetermined temperature. As a result, when the estimated temperature approaches a predetermined threshold, power is supplied to the heater device 12 at shorter intervals, i.e., shorter periods. For example, if the estimated temperature is 10 degrees or more above the predetermined threshold, the intermittent period is set to 30 minutes; if the estimated temperature is 5 to 10 degrees above the predetermined threshold, the intermittent period is set to 10 minutes; and if the estimated temperature is 0 to 5 degrees above the predetermined threshold, the intermittent period is set to 5 minutes. In addition, the intermittent period may be set in multiple stages. If power supply for anti-fogging is not immediately required, the control unit 38 can extend the timing of temperature estimation to reduce power consumption.

[0028] Figure 3 is a flowchart of the power supply control method of the embodiment. The acquisition unit 30 acquires the current and voltage values ​​to the heater device 12, which is supplied with power intermittently, from the current sensor 24 and the voltage sensor 26 (S10). The temperature estimation unit 32 estimates the temperature of the heater device 12 based on the acquired current and voltage values ​​(S12).

[0029] The determination unit 36 ​​determines whether the estimated temperature is below a predetermined threshold (S14). If the estimated temperature is greater than the predetermined threshold (N in S14), the control unit 38 continues to intermittently supply power to the heater device 12 (S10).

[0030] If the estimated temperature is below a predetermined threshold (Y in S14), the determination unit 36 ​​decides to supply power to the heater device 12 (S16). The control unit 38 turns on the relay unit 22 according to the determination result of the determination unit 36 ​​and supplies power to the heater device 12 (S18).

[0031] The heat generation estimation unit 34 estimates the amount of heat generated by the heater device 12 based on the current value, voltage value, and energizing time to the heater device 12 (S20). The determination unit 36 ​​determines whether the estimated amount of heat generated by the heater device 12 is equal to or greater than the set heat amount (S22). If the estimated amount of heat generated is not equal to or greater than the set heat amount (N in S22), the control unit 38 continues to supply power to the heater device 12 (S18).

[0032] If the estimated amount of heat generated is equal to or greater than the set amount (Y in S22), the determination unit 36 ​​decides to terminate the power supply to the heater device 12 (S24). The control unit 38 turns off the relay unit 22 according to the determination result and terminates the power supply to the heater device 12 (S26).

[0033] The present disclosure has been explained above based on the examples described. The present disclosure is not limited to the examples described above, and various modifications such as design changes can be made based on the knowledge of those skilled in the art.

[0034] In this embodiment, the temperature estimation unit 32 is shown to estimate the temperature of the heater device 12. However, the system is not limited to this embodiment, and the resistance value of the heater device 12 may be calculated as a value that increases in conjunction with the temperature. In other words, the temperature estimation unit 32 calculates information regarding the temperature of the heater device 12 based on the current value and voltage value supplied to the heater device 12. The determination unit 36 ​​receives the resistance value of the heater device 12 from the temperature estimation unit 32 as information regarding the temperature of the heater device 12, and decides to start energizing based on that resistance value. The determination unit 36 ​​uses a threshold value based on the resistance value of the heater device 12, and decides to start energizing if the resistance value of the heater device 12 is below the threshold value.

[0035] Furthermore, although the embodiment shows a configuration in which a window located in the imaging direction of the in-vehicle camera is heated, the system is not limited to this configuration. For example, the control system 1 can be applied to heater devices provided in vehicle seats or heater devices provided in steering wheels. In any case, the control system 1 can control the energization of the heater device based on current and voltage values, without requiring a temperature sensor to detect the temperature of the heater device. [Explanation of symbols]

[0036] 1 control system, 10 control device, 12 heater device, 20 power supply control device, 22 relay unit, 24 current sensor, 26 voltage sensor, 28 power input unit, 30 acquisition unit, 32 temperature estimation unit, 34 heat generation estimation unit, 36 determination unit, 38 control unit.

Claims

1. A power supply control device that controls the supply of power to a heater device, An acquisition unit that acquires information indicating the current value of the power supplied to the heater device, A determination unit that determines the heat generated by the heater device based on the acquired information indicating the current value, A power supply control device comprising a control unit that controls the power supply to the heater device according to the determination result of the determination unit.

2. The power supply control device according to claim 1, characterized in that the control unit intermittently supplies power to the heater device when the determination unit has not determined whether the heater device is generating heat.

3. The system further includes a temperature estimation unit that estimates information regarding the temperature of the heater device based on the current value. The determination unit determines the amount of heat generated by the heater device based on the estimated temperature information. The power supply control device according to claim 2, characterized in that the control unit intermittently supplies power to the heater device at shorter intervals than when the estimated temperature is greater than the predetermined temperature, if the estimated temperature is less than or equal to the predetermined temperature.

4. The power supply control device according to claim 3, characterized in that the control unit sets the duty cycle according to information regarding the temperature estimated when the heater device generates heat.

5. The system includes a heat generation estimation unit that estimates the amount of heat generated based on the current and voltage values ​​of the power supplied to the heater device, which are acquired by the acquisition unit. The power supply control device according to claim 3 or 4, characterized in that the determination unit decides to terminate the heating of the heater device based on the estimated amount of heat generated.

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