Power Supply System

Abstract

To enable a power source device to acquire measuring values of a plurality of sensors included in a power supplied device without increasing the number of contacts between devices.SOLUTION: A power supply system 1 includes: a power supplied device 10; and a power source device 20 for supplying power to the power supplied device 10 that is detachably attached. The power supplied device 10 includes: a load 13; load wiring 17 for connecting a load contact to the load 13; first and second sensors 14; sensor wiring 18 for connecting sensor contacts to the first and second sensors 14; and a switching unit 16a for switching the first and second sensors 14. The load wiring 17 and the sensor wiring 18 are not directly connected to each other. The power source device 20 includes: wiring for connecting a power source to the load contact; and a measuring unit 24a connected to the sensor contact and acquiring measurement values of the first and second sensors 14 in accordance with the switching by the switching unit 16a.SELECTED DRAWING: Figure 2A

Description

[Technical Field]

[0001] The present invention relates to a power supply system including a power-supplied device and a power supply device that supplies power to the power-supplied device. [Background technology]

[0002] 5, there is known a power supply system 101 including a power-supplied device 110 such as a cooking appliance and a power supply device 120 that supplies power to the detachably attached power-supplied device 110. The power-supplied device 110 has first and second load contacts 11a, 11b and first and second sensor contacts 12a, 12b, and the power supply device 120 has first and second load contacts 21a, 21b and first and second sensor contacts 22a, 22b. When the powered device 110 is attached to the power supply device 120 and the adapters of both devices are connected, the first and second load contacts 11a and 11b provided on the adapter of each device are connected to the first and second load contacts 21a and 21b, respectively, and the first and second sensor contacts 12a and 12b are connected to the first and second sensor contacts 22a and 22b, respectively. As a result, AC power from the commercial power source 2 is supplied from the power supply device 120 to the load 13 of the powered device 110, and the value of the sensor 14 of the powered device 110 is acquired by the measuring unit 124a of the power supply device 120. The load 13 may be, for example, a heater used in a cooking appliance. The sensor 14 may be a temperature sensor such as a thermistor. Furthermore, the power supply device 120 has a power supply circuit 123 that can convert AC to DC, and the measurement unit 124a and the like can acquire the measurement value of the sensor 14 using the DC.

[0003] Specifically, when sensor 14 is a passive sensor of a resistance output type such as a thermistor, the resistance value of sensor 14 can be obtained by detecting a divided voltage value between sensor 14 and resistor 25, whose resistance value is known, and the temperature, etc. can be obtained using the resistance value. For example, in FIG. 5, when powered device 110 is attached to power supply device 120, measurement unit 124a sets first sensor contact 22a to a predetermined potential and measures the voltage of second sensor contact 22b, thereby obtaining the resistance value of sensor 14. Then, measurement unit 124a can obtain the temperature from the relationship between temperature and resistance value.

[0004] In such a conventional power supply system 101, there has been a demand for increasing the number of sensors used in the power supplied device 110 without increasing the number of contacts in the adapter. To this end, it is conceivable to configure the power supplied device 110 and the power supply device 120 as shown in FIG. 6. The power supply circuit 123 in the power supply system 101 shown in FIG. 6 is assumed to be a half-wave rectifier circuit. Then, by using the first load contact 21a as the reference potential, the measurement unit 124b can obtain the temperatures of the first and second sensors 14-1 and 14-2 by detecting the divided voltage values ​​of the first and second sensors 14-1 and 14-2 and the resistors 25a and 25b, each having a known resistance value. Summary of the Invention [Problem to be solved by the invention]

[0005] However, in the power supply system 101 shown in FIG. 6, if the connection between the first load contact 11a at the reference potential and the first load contact 21a is broken when the power supply device 110 is removed or due to a contact failure or the like while power is being supplied to the power supply device 110, an AC overvoltage will be applied to the first and second sensors 14-1, 14-2 and the measuring unit 124b, causing an excessive current to flow and resulting in a breakdown of the device.

[0006] Furthermore, when current is flowing through load 13 such as a heater, a current of about several amperes flows through first load contacts 11a, 21a, and the contact resistance at these contacts causes a deviation in the reference potential between powered device 110 and power supply device 120, making it impossible to accurately measure the resistance values ​​of sensors 14-1, 14-2. The degree of deviation in the reference potential differs depending on the device and changes over time, making it difficult to accurately measure the resistance values ​​of sensors 14-1, 14-2.

[0007] The present invention has been made to solve the above-mentioned problems, and aims to provide a power supply system that can perform more accurate measurements using two or more sensors in a power-supplied device without increasing the number of contacts, and that can prevent the device from breaking down. [Means for solving the problem]

[0008] In order to achieve the above-mentioned object, a power supply system according to one aspect of the present invention is a power supply system comprising a powered device and a power supply device that supplies power to a detachably attached powered device, wherein the power supply device and the powered device each have two load contacts and two sensor contacts that are connected when the powered device is attached to the power supply device, the powered device comprises a load, load wiring for connecting the load contacts to the load, first and second sensors, sensor wiring for connecting the sensor contacts to the first and second sensors, and a switching unit for switching between the first and second sensors, wherein the load wiring and the sensor wiring in the powered device are not directly connected, and the power supply device comprises wiring for connecting a power source to the load contacts and a measurement unit that is connected to the sensor contacts and acquires measurement values ​​of the first and second sensors in response to switching by the switching unit. With this configuration, the power supply device can switch between sensors using a switching unit, allowing the power supply device to acquire measurements from the first and second sensors without increasing the number of contacts. Furthermore, since the load wiring and the sensor wiring are not directly connected in the power supply device, even if a contact in one of the wirings for supplying power to the load is disconnected, excessive current flowing through the load wiring will not flow to the sensor or measurement unit, preventing device failure. Furthermore, since measurements are performed using the sensor without using the load contacts, they are not affected by potential deviations at the load contacts.

[0009] In addition, in a power supply system according to one aspect of the present invention, the power source may be an AC power source, the switching unit may switch between the first and second sensors depending on the phase of the AC voltage in the load wiring, and the measurement unit may perform measurements on the first and second sensors depending on the phase of the AC voltage in the wiring connected to the AC power source. With this configuration, the switching timing and measurement timing of the two sensors can be synchronized using the phase of the AC, making it possible to obtain measurements from the first and second sensors in the power supply device.

[0010] In addition, in a power supply system according to one aspect of the present invention, the switching unit may have a first reverse current prevention element connected in series with the first sensor and a second reverse current prevention element connected in series with the second sensor, the first and second reverse current prevention elements being connected in parallel and in reverse directions, and the measurement unit may perform measurements on the first sensor by supplying a direct current so that the first reverse current prevention element is in the forward direction and the second reverse current prevention element is in the reverse direction, and may perform measurements on the second sensor by supplying a direct current so that the second reverse current prevention element is in the forward direction and the first reverse current prevention element is in the reverse direction. With this configuration, the first and second sensors can be switched by changing the direction of the direct current supplied to the first and second sensors, and the power supply device can obtain measurements from the first and second sensors. [Effects of the Invention]

[0011] According to one aspect of the present invention, a power supply system can be used to measure power using at least two sensors without increasing the number of contacts. Furthermore, excessive current flowing through the load wiring does not flow into the sensors or measurement circuit, preventing device failure. Furthermore, the system is not affected by potential deviations at the load contacts, enabling more accurate measurements using sensors. [Brief explanation of the drawings]

[0012] [Figure 1] FIG. 1 is a perspective view showing an external appearance of a power supply system according to a first embodiment of the present invention; [Figure 2A] FIG. 2 is a block diagram showing the configuration of a power supply system according to the embodiment. [Figure 2B] FIG. 2 is a circuit diagram showing the configuration of an AC phase detection circuit according to the embodiment; [Figure 3A] FIG. 10 is a block diagram showing the configuration of a power supply system according to a second embodiment of the present invention. [Figure 3B] FIG. 2 is a circuit diagram showing a configuration of a switching unit in the embodiment; [Figure 4] FIG. 10 is a block diagram showing the configuration of a power supply system according to a third embodiment of the present invention. [Figure 5] Block diagram showing the configuration of a conventional power supply system [Figure 6] Block diagram showing another configuration of a conventional power supply system DETAILED DESCRIPTION OF THE INVENTION

[0013] Hereinafter, a power supply system according to the present invention will be described using embodiments. In the following embodiments, components with the same reference numerals are the same or equivalent, and repeated description may be omitted.

[0014] (Embodiment 1) A power supply system according to a first embodiment of the present invention will be described with reference to the drawings. The power supply system according to this embodiment switches sensors depending on the phase of an AC voltage.

[0015] Fig. 1 is a perspective view showing the appearance of a power supply system 1 according to this embodiment, Fig. 2A is a block diagram showing the configuration of the power supply system 1, and Fig. 2B is a circuit diagram showing an example of the configuration of an AC phase detection circuit 41. Note that the configuration described in the power supply system 101 of the conventional example may not be described again.

[0016] The power supply system 1 according to the present embodiment includes a power supplied device 10 and a power supply device 20. In the present embodiment, a case will be mainly described in which the power supplied device 10 is a cooking appliance and the power supply device 20 is a power stand on which the power supplied device 10, which is a cooking appliance, is placed, but the power supplied device 10 may be a device other than a cooking appliance.

[0017] The power-supplied device 10 includes first and second load contacts 11a and 11b, first and second sensor contacts 12a and 12b, a load 13, first and second sensors 14-1 and 14-2, a switching unit 16a, load wiring 17 for connecting the first and second load contacts 11a and 11b to the load 13, and sensor wiring 18 for connecting the first and second sensor contacts 12a and 12b to the first and second sensors 14-1 and 14-2. As shown in FIG. 2A , in the power-supplied device 10, the load wiring 17 and the sensor wiring 18 are connected only via the switching unit 16a, not directly. Therefore, even if one of the load contacts is disconnected while power is being supplied to the load 13, an excessive current does not flow through the sensor wiring 18. Note that a direct connection may also refer to a connection having a direct connection point without passing through another component. The switching unit 16a also includes an AC phase detection circuit 31 and a switch 32. When the first and second sensors 14-1 and 14-2 are not particularly distinguished from each other, they may be referred to as sensors 14.

[0018] The power supply device 20 supplies power to the detachably attached powered device 10 and includes first and second load contacts 21a, 21b, first and second sensor contacts 22a, 22b, a power supply circuit 23, a measurement unit 24a, a resistor 25, load wiring 26 for connecting the commercial power supply 2 to the first and second load contacts 21a, 21b, and sensor wiring 27 for connecting the measurement unit 24a to the first and second sensor contacts 22a, 22b. The measurement unit 24a also includes an AC phase detection circuit 41 and an acquisition unit 42. The power supply device 20 may be connected to the commercial power supply 2 by inserting a plug at the end of a power cord 20a of the power supply device 20 into an outlet, and AC power from the commercial power supply 2 may be supplied to the power supply device 20. Although not shown in FIG. 2A , the power supply device 20 may also include a control circuit for controlling the load 13 in accordance with the measurement value of the sensor 14.

[0019] The first and second load contacts 11a, 11b and the first and second sensor contacts 12a, 12b of the powered device 10 are connected to the first and second load contacts 21a, 21b and the first and second sensor contacts 22a, 22b of the power supply device 20 by attaching the powered device 10 to the power supply device 20 and connecting an adapter (not shown) on the powered device 10 side to an adapter 20b on the power supply device 20 side. Power is then supplied from the power supply device 20 to the load 13, and measurements from the two sensors 14 are acquired by the power supply device 20. Note that in this embodiment, a case where the adapter has four contacts, two contacts for the load and two contacts for the sensor, will be mainly described. However, for products intended for overseas markets, the adapter may have five contacts, including an additional ground contact. Because the five-contact adapter is similar to the four-contact adapter except for the ground contact, the following description will focus on the four-contact adapter. It goes without saying that the shape of the adapter is not limited to that shown in Figure 1. As long as the adapter can connect and disconnect at least four contacts, there is no restriction on the shape or configuration.

[0020] In this embodiment, the case where the load 13 is a cooking heater and the first and second sensors 14-1 and 14-2 are temperature sensors (e.g., thermistors) will be mainly described. The temperature sensor 14 may be any sensor selected from, for example, a sensor for measuring water temperature, a sensor for measuring the internal temperature of the object being cooked, a sensor for measuring steam, or a sensor for measuring the temperature of a specific location on the cooker. In this embodiment, the first and second sensors 14-1 and 14-2 measure temperatures at different locations on the cooker. Note that the load 13 may also be a motor or a light other than a heater. The first and second sensors 14-1 and 14-2 may also be sensors other than thermistors. However, it is preferable that the first and second sensors 14-1 and 14-2 are passive sensors with a resistive output. A resistive output sensor is a sensor that can acquire a sensor measurement value by measuring the resistance value of the sensor. Resistance output passive sensors other than thermistors are not particularly limited, and may be, for example, optical sensors (CdS), resistive position sensors, strain gauges, resistance change type humidity sensors, or the like.

[0021] The switching unit 16a switches between the first and second sensors 14-1 and 14-2. The sensor 14 connected to the power supply device 20, i.e., the sensor 14 to be measured, is switched in response to the switching by the switching unit 16a. This switching may be performed under control of the power supply device 20 or may be performed in the power-supplied device 10. In this embodiment, a case where the sensor is switched depending on the phase of the AC voltage is described. In a second embodiment, a case where the sensor is switched depending on the direction of the current supplied from the power supply device 20 is described. In a third embodiment, a case where these are combined is described. As a result, the first and second sensors 14-1 and 14-2 can be individually measured using any method. In this embodiment, a case where the switching unit 16a switches between a state where the resistance value of only the first sensor 14-1 is measured and a state where the combined resistance value of the first and second sensors 14-1 and 14-2 connected in parallel is measured is mainly described. In the power supply device 20, the resistance value of the first sensor 14-1 can be measured in the former situation, and the resistance value of the second sensor 14-2 can be obtained using the resistance value of the first sensor 14-1 and the combined resistance value measured in the latter situation.

[0022] The switching unit 16a switches between the first and second sensors 14-1 and 14-2 in accordance with the phase of the AC voltage in the load wiring 17. More specifically, the AC phase detection circuit 31 included in the switching unit 16a detects the phase of the AC voltage supplied to the load 13 and outputs a signal in accordance with the detection result. The switch 32 then opens and closes in accordance with the output, thereby performing the switching. The AC phase detection circuit 31 may be, for example, a zero-crossing detector. In this case, the switch opens and closes each time a zero-crossing is detected in the AC voltage in the load wiring 17. For example, the switch 32 may be open when the voltage phase is between 0 and π, and closed when the voltage phase is between π and 2π. The switch 32 may be, for example, a MOSFET (Metal-Oxide-Semiconductor Field-Effect Transistor) or another switching element.

[0023] Power supply circuit 23 of power supply device 20 is connected to load wiring 26, and converts AC power from commercial power supply 2 into DC power and supplies it to measurement unit 24a. In power supply circuit 23, AC / DC conversion may be performed by, for example, a half-wave rectifier or a full-wave rectifier. In power supply circuit 23, voltage conversion may also be performed using a transformer, switching element, or the like, and a predetermined DC voltage may be supplied to measurement unit 24a.

[0024] The measurement unit 24a is connected to the first and second sensor contacts 22a and 22b and acquires the measured values ​​of the first and second sensors 14-1 and 14-2 in response to switching by the switching unit 16a. The measurement unit 24a performs measurements in response to switching of the sensors 14 by the switching unit 16a, thereby acquiring the measured values ​​of the first and second sensors 14-1 and 14-2. In this embodiment, the measurement unit 24a mainly performs measurements of the first and second sensors 14-1 and 14-2 in response to the phase of the AC voltage in the load wiring 26 connected to the AC power source. More specifically, the AC phase detection circuit 41 included in the measurement unit 24a is similar to the AC phase detection circuit 31 and detects the phase of the AC voltage supplied to the load 13 and outputs a signal in accordance with the detection result. Then, according to the output, the acquiring unit 42 acquires the resistance value of only the first sensor 14-1 or the combined resistance value of the first and second sensors 14-1, 14-2 connected in parallel, thereby acquiring the resistance values ​​of the first and second sensors 14-1, 14-2 and the measured values ​​of each sensor 14. In this way, in the present embodiment, the switching of the sensors 14 in the power supplied device 10 and the switching of measurements in the power supply device 20 are synchronized by the phase of the AC voltage.

[0025] Resistor 25 has a known resistance value and is used to measure the resistance value of first sensor 14-1 or the combined resistance value of first and second sensors 14-1 and 14-2. Acquiring unit 42 can acquire the resistance value of the resistor to be measured by detecting the divided voltage value between the resistor to be measured and resistor 25 when first sensor contact 22a is at a predetermined potential.

[0026] The AC phase detection circuit 41 may be configured as shown in FIG. 2B, for example. The AC phase detection circuit 41 shown in FIG. 2B includes a diode 51, a resistor 52 connected in series to the anode of the diode 51, a capacitor 53 connected in parallel to the diode 51, and a PNP bipolar transistor 54 having a base connected to the anode of the diode 51 and an emitter connected to the cathode of the diode 51. The cathode of the diode 51 and the end of the resistor 52 opposite the diode 51 are connected to an AC power supply, and the collector of the bipolar transistor 54 serves as an output. This output alternates between ON and OFF each time the AC voltage crosses zero. This output is input to the acquisition unit 42. Therefore, the acquisition unit 42 can determine, based on the output, whether the phase of the AC voltage is between 0 and π or between π and 2π. The AC phase detection circuit 31 may also have a configuration similar to that of the AC phase detection circuit 41. The output of AC phase detection circuit 31 is input to switch 32, thereby opening and closing switch 32. For example, the output may be input to the gate of switch 32, which is a MOSFET.

[0027] Next, measurement using two sensors 14 in the power supply system 1 according to this embodiment will be described. Here, it is assumed that the switch 32 is open when the phase of the AC voltage is between 0 and π, and is closed when the phase is between π and 2π. When the powered device 10 is attached to the power supply device 20, the measurement unit 24a outputs a DC voltage to the powered device 10 so that the potential of the first sensor contact 22a becomes a predetermined value (for example, 5 V). The acquisition unit 42 can know the switching timing of the switch 32 from the output of the AC phase detection circuit 41. Therefore, the acquisition unit 42 can acquire the resistance value R1 of the first sensor 14-1 according to the potential of the second sensor contact 22b measured when the phase of the AC voltage is between 0 and π, and thereby acquire the temperature of the first sensor 14-1. The acquisition unit 42 also acquires a combined resistance value R of the first and second sensors 14-1, 14-2 according to the potential of the second sensor contact 22b measured when the phase of the AC voltage is between π and 2π, and can acquire a resistance value R2 of the second sensor 14-2 using the resistance value R and the resistance value R1 of the first sensor 14-1 acquired immediately before, as shown in the following equation: The acquisition unit 42 can also acquire the temperature of the second sensor 14-2 using the resistance value R2. In this way, measurement using two sensors 14 can be achieved. R2 = R1 × R / (R1 - R)

[0028] In the present embodiment, the AC phase detection circuits 31 and 41 may detect the phase using a photocoupler. Phase detection using a photocoupler is effective in improving insulation when the potentials of the sensor 14 or the acquisition unit 42 are different from those of the AC phase detection circuits 31 and 41. Although the present embodiment describes a case in which the AC phase detection circuits 31 and 41 are zero-crossing detectors, this is not necessarily the case. For example, the AC phase detection circuits 31 and 41 may detect the timing at which the AC voltage reaches a maximum or minimum. In this case, the switch 32 may be switched at the timing at which the AC voltage reaches a maximum or minimum. Although the present embodiment describes a case in which the AC phase detection circuits 31 and 41 detect the phase of the AC voltage, because there is a predetermined relationship between the phase of the AC voltage and the phase of the AC current, the AC phase detection circuits 31 and 41 may also be considered to detect the phase of the AC current. Furthermore, in the present embodiment, the resistance value of the first sensor 14-1 acquired immediately before is used to calculate the resistance value of the second sensor 14-2. However, this is not necessarily the case. For example, when calculating the resistance value of the second sensor 14-2, the resistance value of the first sensor 14-1 acquired immediately after the first sensor 14-1 is calculated may be used, or the average of the resistance values ​​of the first sensor 14-1 acquired immediately before and after the first sensor 14-1 may be used. In the present embodiment, the switching unit 16a mainly switches between a state in which the resistance value of only the first sensor 14-1 is measured and a state in which the combined resistance value of the first and second sensors 14-1 and 14-2 connected in parallel is measured. However, this is not essential. The switching unit 16a may also switch between a state in which the resistance value of only the first sensor 14-1 is measured and a state in which the resistance value of only the second sensor 14-2 is measured. In this case, for example, another switch may be connected in series with the first sensor 14-1. The switch connected in series with the first sensor 14-1 may be controlled by the output of the AC phase detection circuit 31 to be in an open / closed state opposite to the open / closed state of the switch 32.

[0029] As described above, according to the power supply system 1 of this embodiment, by switching between the first and second sensors 14-1, 14-2 using the switching unit 16a, it is possible to acquire measurements from two sensors 14 in the power supply device 20 using a general-purpose adapter without increasing the number of contacts in the adapter. Furthermore, since the load wiring 17 and the sensor wiring 18 in the power supplied device 10 are not directly connected, even if the connection between one of the first load contacts 11a, 21a and the second load contacts 11b, 21b is broken, it is possible to prevent an excessive current from flowing through the load wiring 17 to the sensor 14 or the measuring unit 24a, thereby avoiding a breakdown in the power supply system 1. Furthermore, because measurements are performed by the sensor 14 without going through the load contacts, they are not affected by a potential deviation due to a high current at the load contacts, allowing for highly accurate measurements.

[0030] (Embodiment 2) A power supply system according to a second embodiment of the present invention will be described with reference to the drawings. In the power supply system according to this embodiment, sensors are switched depending on the direction of current supplied from a power supply device.

[0031] Fig. 3A is a block diagram showing the configuration of power supply system 1 according to the present embodiment, and Fig. 3B is a circuit diagram showing an example of the configuration of switching unit 16b. Note that repeated explanation of the configurations described in the conventional example or embodiment 1 may be omitted. As shown in Fig. 3A, in power supply system 1 according to the present embodiment, power supplied device 10 includes switching unit 16b instead of switching unit 16a, and power supply device 20 includes measuring unit 24b and resistors 25a and 25b instead of measuring unit 24a and resistor 25.

[0032] The switching unit 16b includes a first reverse current prevention element 33 connected in series with the first sensor 14-1 and a second reverse current prevention element 34 connected in series with the second sensor 14-2. The first and second reverse current prevention elements 33, 34 are connected in parallel and in opposite directions. That is, the first sensor 14-1 and the first reverse current prevention element 33 connected in series and the second sensor 14-2 and the second reverse current prevention element 34 connected in series are connected in parallel so that the directions of the currents flowing therethrough are opposite to each other.

[0033] The first and second reverse current prevention elements 33, 34 may be of any type as long as they have a rectifying effect of allowing current to flow in only one direction. The first and second reverse current prevention elements 33, 34 may be, for example, a PN junction diode, a Schottky barrier diode, or a MOSFET connected to have a rectifying effect. Note that, in view of the small potential difference between the anode and cathode sides, it is preferable to use a MOSFET connected to have a rectifying effect as the first and second reverse current prevention elements 33, 34.

[0034] As the first and second reverse current prevention elements 33 and 34, for example, as shown in FIG. 3B, P-type MOSFETs requiring a low gate ON voltage may be used. As shown in FIG. 3B, the P-type MOSFET serving as the first reverse current prevention element 33 has a drain connected to the first sensor contact 12a, a gate connected to the end of the first sensor 14-1 on the second sensor contact 12b side, and a source connected to the other end of the first sensor 14-1. The P-type MOSFET serving as the second reverse current prevention element 34 has a drain connected to the second sensor contact 12b, a gate connected to the end of the second sensor 14-2 on the first sensor contact 12a side, and a source connected to the other end of the second sensor 14-2. Therefore, in FIG. 3B, current flows only from top to bottom in the first sensor 14-1, and current flows only from bottom to top in the second sensor 14-2. If the ON voltage of the MOSFET cannot be ensured depending on the voltage division with the resistors 25a and 25b, the potential applied to the anode sides of the first and second reverse current prevention elements 33 and 34 may be increased.

[0035] The measuring unit 24b of the power supply device 20 measures the first sensor 14-1 by supplying a DC current to the powered device 10 so that the first reverse current prevention element 33 is in the forward direction and the second reverse current prevention element 34 is in the reverse direction. In this case, the resistor 25b is used as a resistor with a known resistance value for detecting the divided voltage value. The measuring unit 24b also measures the second sensor 14-2 by supplying a DC current to the powered device 10 so that the second reverse current prevention element 34 is in the forward direction and the first reverse current prevention element 33 is in the reverse direction. In this case, the resistor 25a is used as a resistor with a known resistance value for detecting the divided voltage value. As described above, in the present embodiment, the sensor 14 is switched by turning one of the first and second reverse current prevention elements 33 and 34 of the switching unit 16b ON and the other OFF depending on the direction of the DC current supplied from the power supply device 20. That is, the switching of the sensor 14 by the switching unit 16b is controlled by the measuring unit 24b.

[0036] Next, measurement using two sensors 14 in the power supply system 1 according to this embodiment will be described. With the power-supplied device 10 attached to the power supply device 20, the measurement unit 24b first sets the first sensor contact 22a to a predetermined positive potential (e.g., 5 V). Then, a direct current is supplied to the power-supplied device 10 so that the current flows from the first sensor contact 12a to the second sensor contact 12b. In this case, the first reverse-current prevention element 33 is in the forward direction, but the second reverse-current prevention element 34 is in the reverse direction. Therefore, a current flows through the first sensor 14-1, but no current flows through the second sensor 14-2. Therefore, the measurement unit 24b can acquire the measurement value of the first sensor 14-1 by measuring the potential on the second sensor contact 22b side.

[0037] Then, the measurement unit 24b sets the second sensor contact 22b to a predetermined positive potential. This causes a DC current to be supplied to the powered device 10 so that the current flows from the second sensor contact 12b to the first sensor contact 12a. In this case, the first reverse current prevention element 33 is in the reverse direction, but the second reverse current prevention element 34 is in the forward direction. Therefore, no current flows through the first sensor 14-1, but a current flows through the second sensor 14-2. Therefore, the measurement unit 24b can obtain the measurement value of the second sensor 14-2 by measuring the potential on the first sensor contact 22a.

[0038] As described above, according to the power supply system 1 of this embodiment, the switching unit 16b is connected in series with the first and second sensors 14-1 and 14-2, respectively, and has the first and second reverse current prevention elements 33 and 34 connected in parallel and in opposite directions to each other, so that the measurement unit 24b can switch the sensor 14 to be measured by switching the direction of the current, and can measure each sensor 14. Furthermore, as with the power supply system 1 of the first embodiment, failures can be avoided and highly accurate measurements can be achieved.

[0039] In the power supply system 1 according to the present embodiment, the switching unit 16b does not use AC voltage to switch between the two sensors 14. Therefore, the power supplied from the power supply device 20 to the power supplied device 10 may be DC power. In this case, for example, the power supply device 20 may be connected to a DC power supply or may have a DC power supply such as a battery built in. Also, the power supply circuit 23 may be, for example, a circuit that converts a high DC voltage supplied to the load 13 into a low voltage for measurement by the sensor 14. Also, if the DC voltage supplied to the load 13 and the voltage for measurement by the sensor 14 are the same, the power supply device 20 does not need to include the power supply circuit 23.

[0040] (Embodiment 3) A power supply system according to a third embodiment of the present invention will be described with reference to the drawings. The power supply system according to this embodiment is capable of performing measurements using four sensors by combining the sensor switching method of the first embodiment and the sensor switching method of the second embodiment. That is, the system switches sensors according to the phase of the AC voltage and the direction of the current.

[0041] FIG. 4 is a block diagram showing the configuration of a power supply system 1 according to this embodiment. Note that repeated description of the configurations described in the conventional example or the first and second embodiments may be omitted. As shown in FIG. 4, in the power supply system 1 according to this embodiment, the power supplied device 10 includes a switching unit 16c instead of the switching units 16a and 16b, and the power supply device 20 includes a measuring unit 24c instead of the measuring units 24a and 24b. The power supplied device 10 also includes third and fourth sensors 14-3 and 14-4. The third and fourth sensors 14-3 and 14-4 are preferably passive sensors of a resistive output type.

[0042] The switching unit 16c includes first to fourth reverse current prevention elements 33, 34, 39, and 40, AC phase detection circuits 35 and 37, and switches 36 and 38. The first to fourth reverse current prevention elements 33, 34, 39, and 40 of this embodiment are similar to the first and second reverse current prevention elements 33 and 34 of the second embodiment. The first to fourth reverse current prevention elements 33, 34, 39, and 40 are connected in series with the first to fourth sensors 14-1 to 14-4, respectively. The first to fourth reverse current prevention elements 33, 34, 39, and 40 are connected in parallel, and the first and fourth reverse current prevention elements 33 and 40 and the second and third reverse current prevention elements 34 and 39 are connected in opposite directions. Furthermore, AC phase detection circuits 35 and 37 are similar to AC phase detection circuit 31 of embodiment 1, and switches 36 and 38 are similar to switch 32 of embodiment 1. Although not shown in FIG. 4, measurement unit 24c is assumed to have an AC phase detection circuit similar to AC phase detection circuit 41 of embodiment 1.

[0043] Next, measurement using the four sensors 14 in the power supply system 1 according to this embodiment will be described. With the power-supplied device 10 attached to the power supply device 20, the measurement unit 24c first sets the first sensor contact 22a to a predetermined positive potential. Then, a DC current is supplied to the power-supplied device 10 so that current flows from the first sensor contact 12a to the second sensor contact 12b. In this case, the first and fourth reverse-current prevention elements 33 and 40 are forward-biased, while the second and third reverse-current prevention elements 34 and 39 are reverse-biased. Therefore, current flows through the first sensor 14-1. When the switch 38 is closed, current also flows through the fourth sensor 14-4. However, no current flows through the second and third sensors 14-2 and 14-3. The AC phase detection circuit 37 opens and closes the switch 38 depending on the phase of the AC voltage. Therefore, by measuring the potential on the side of the second sensor contact 22b, the measurement unit 24c can measure the resistance value of the first sensor 14-1 and the combined resistance value of the first and fourth sensors 14-1, 14-4 according to the phase of the AC voltage, and can obtain the measurement values ​​of the first and fourth sensors 14-1, 14-4, respectively.

[0044] Then, the measurement unit 24c adjusts the second sensor contact 22b to a predetermined positive potential. This causes DC current to flow from the second sensor contact 12b to the first sensor contact 12a. In this case, the first and fourth reverse current prevention elements 33 and 40 are reverse-directed, while the second and third reverse current prevention elements 34 and 39 are forward-directed. Therefore, current flows through the second sensor 14-2. When the switch 36 is closed, current also flows through the third sensor 14-3. However, no current flows through the first and fourth sensors 14-1 and 14-4. The AC phase detection circuit 35 opens and closes the switch 36 depending on the phase of the AC voltage. Therefore, by measuring the potential on the side of the first sensor contact 22a, the measurement unit 24c can measure the resistance value of the second sensor 14-2 and the combined resistance value of the second and third sensors 14-2, 14-3 according to the phase of the AC voltage, and can obtain the measurement values ​​of the second and third sensors 14-2, 14-3, respectively.

[0045] As described above, the power supply system 1 according to this embodiment can perform measurements using the four sensors because it is possible to switch between the four sensors 14. Furthermore, similar to the power supply systems 1 according to the first and second embodiments, it is possible to avoid failures and achieve highly accurate measurements.

[0046] In each of the above embodiments, the switching unit included in the power supplied device 10 is not limited to the above-described one, as long as it can appropriately switch the sensor 14 connected to the power supply device 20 from among the multiple sensors 14. In addition, the measurement unit included in the power supply device 20 is also not limited to the above-described one, as long as it can acquire the measured values ​​of the sensors 14 in response to the switching of the sensors 14 by the switching unit.

[0047] Furthermore, the present invention is not limited to the above-described embodiment, and various modifications are possible, and it goes without saying that these modifications are also included within the scope of the present invention. [Explanation of symbols]

[0048] 1 Power supply system 10 Powered Equipment 13 Load 14-1, 14-2, 14-3, 14-4 1st to 4th sensors 16a, 16b, 16c Switching section 20 Power supply 24a, 24b, 24c measurement section 33, 34, 39, 40 First to fourth reverse current prevention elements

Claims

1. A power supply system including a power-supplied device and a power supply device that supplies power to the power-supplied device, the power supply device being detachably attached, the power supply device and the powered device each have two load contacts and two sensor contacts that are connected when the powered device is attached to the power supply device, When the powered device is attached to the power supply device, the two devices are electrically connected to each other only by the two load contacts and the two sensor contacts, The power-supplied device is Load and a load wiring for connecting the load contact and the load; first and second sensors; a sensor wiring for connecting the sensor contacts to the first and second sensors; a switching unit for switching between the first and second sensors, In the power-supplied device, the load wiring and the sensor wiring are not directly connected, The power supply device Wiring for connecting a power source to the load contacts; a measurement unit connected to the sensor contacts and configured to acquire measurement values ​​of the first and second sensors in response to switching by the switching unit.

2. the power source is an AC power source; the switching unit switches between the first and second sensors in accordance with a phase of the AC voltage in the load wiring; The power supply system according to claim 1 , wherein the measurement unit performs measurements on the first and second sensors in accordance with a phase of an AC voltage in a wiring connected to the AC power source.

3. The switching unit is a first reverse current prevention element connected in series with the first sensor; a second reverse current prevention element connected in series with the second sensor; the first and second reverse current prevention elements are connected in parallel and in opposite directions; 2. The power supply system according to claim 1, wherein the measurement unit performs measurements on the first sensor by supplying a direct current so that the first reverse current prevention element is in a forward direction and the second reverse current prevention element is in a reverse direction, and performs measurements on the second sensor by supplying a direct current so that the second reverse current prevention element is in a forward direction and the first reverse current prevention element is in a reverse direction.

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