JP2016052172A - Transmission apparatus and non-contact power transmission apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a transmission apparatus and non-contact power transmission apparatus, capable of suitably suppressing abnormality of a DC-AC converter.SOLUTION: The transmission apparatus 11 includes a voltage source 12 having a DC-AC converter 12b for converting DC power into AC power, and a transmitter 13 for inputting AC power. The transmission apparatus 11 includes: an output voltage value measuring section 31 for measuring an output voltage value Vout; a power factor detector 32 for detecting a power factor; and a transmission-side controller 14 for stopping an output of AC power when an output voltage value Vout measured by the output voltage value measuring section 31 is higher than a threshold voltage value and a power factor detected by the power factor detector 32 is lower than a threshold power factor.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a power transmission device and a contactless power transmission device.

  As a non-contact power transmission device that does not use a power cord or a power transmission cable, for example, an AC power source that outputs AC power of a predetermined frequency, and a power transmission device that has a primary coil to which the AC power is input, What is provided with the power receiving apparatus which has the secondary side coil which can receive alternating current electric power from a primary side coil non-contacting is known (for example, refer patent document 1). In such a non-contact power transmission device, AC power is transmitted from a power transmitting device to a power receiving device in a non-contact manner, for example, by magnetic resonance between the primary side coil and the secondary side coil.

JP 2009-106136 A

  The AC power source includes, for example, a DC / AC conversion unit that converts DC power into the AC power. Here, even when DC power having an excessive power value is not input to the DC / AC converter, the power loss of the DC / AC converter becomes excessively large when the power factor is low. There is a case. In this case, there is a concern about abnormality such as heat generation of the DC / AC conversion unit.

  This invention is made | formed in view of the situation mentioned above, The objective is to provide the power transmission apparatus and non-contact electric power transmission apparatus which can suppress the abnormality of a DC / AC conversion part suitably.

  A power transmission device that achieves the above object includes a DC / AC conversion unit that converts DC power into AC power having a predetermined frequency, and a voltage source that outputs the AC power and the AC power are input 1 A secondary coil, capable of transmitting the AC power in a non-contact manner to the secondary coil of a power receiving device having a secondary coil, and an input voltage value of the DC / AC converter Alternatively, based on the output voltage value and the power factor or the current difference between the input current value and the output current value of the DC / AC converter, the output of the AC power from the voltage source is stopped, or the AC A control unit that reduces the power value of the power is provided.

  According to such a configuration, the output of AC power is stopped based on the input voltage value or output voltage value of the DC / AC converter and the current difference between the power factor or the input current value and output current value of the DC / AC converter. Etc. are performed. As a result, for example, when the power loss of the DC / AC converter is excessively large due to the power factor being excessively low in a situation where the input voltage value or the output voltage value is normal, the AC power Can be stopped, and the abnormality of the DC / AC converter can be avoided through the output. Therefore, the abnormality of the DC / AC converter can be suitably suppressed.

  In particular, in a configuration in which a voltage source is used as an AC power supply, an input voltage value or an output voltage value of a DC / AC conversion unit is employed as a parameter for determining whether output of AC power is stopped. The input voltage value and the output voltage value are not easily affected by fluctuations in the input impedance of the primary side coil. Thereby, even if the input impedance of the primary side coil fluctuates due to a change in the relative position between the primary side coil and the secondary side coil, it is possible to suitably stop the output of the AC power. .

  The power transmission device includes a measurement unit that measures the input voltage value or the output voltage value, and a power factor detection unit that detects the power factor, and the control unit is a measurement value measured by the measurement unit. Output of the AC power from the voltage source when the power factor detected by the power factor detector is lower than a predetermined threshold power factor. May be stopped, or the power value of the AC power may be reduced. According to this configuration, when the measured value is higher than the threshold measured value and the power factor is lower than the threshold power factor, the output of AC power is stopped or the power value of AC power is reduced. Thereby, abnormality of a DC / AC conversion part can be controlled suitably.

  Here, when the output current value or output power value of the voltage source is adopted as a parameter for determining the output stop of the AC power, it is necessary to set the threshold measurement value corresponding to the output current value or the output power value. There is. The output current value and output power value of the voltage source fluctuate according to the input impedance of the primary side coil, and the input impedance of the primary side coil depends on the relative position of the primary side coil and the secondary side coil, etc. Fluctuate accordingly. For this reason, when setting the threshold measurement value corresponding to the output current value or the output power value that may vary according to the fluctuation of the input impedance of the primary coil, the setting of the threshold measurement value becomes complicated, Due to the fluctuation of the input impedance of the primary coil, there may be a problem that the output of AC power is stopped by mistake.

  On the other hand, according to the present configuration, an input voltage value or an output voltage value that is not easily affected by fluctuations in the input impedance of the primary coil is employed as a parameter for determining whether or not AC power output is stopped. Inconveniences as described above can be avoided.

  For the power transmission device, the control unit, even when the power factor is lower than the threshold power factor, if the measured value is less than or equal to the threshold measured value, without changing the power value It is good to continue the output of AC power. Even when the power factor is lower than the threshold power factor, the power loss in the DC / AC converter is relatively small when the measured value is equal to or less than the threshold measured value. In this regard, according to this configuration, even when the power factor is lower than the threshold power factor, if the measured value is equal to or lower than the threshold measured value, the output of the AC power is not changed without changing the power value. Will continue. Thereby, it is possible to avoid unnecessary AC power output stop or the like in a situation where the power loss in the DC / AC converter is relatively small.

  For the power transmission device, the threshold measurement value is a first threshold measurement value, and the control unit is a second threshold measurement value in which the power factor is greater than or equal to the threshold power factor and the measurement value is predetermined. The output of the AC power from the voltage source is stopped, or the power value of the AC power is reduced, and the second threshold measurement value is smaller than the first threshold measurement value. It should be set high. According to this configuration, when the power factor is equal to or higher than the threshold power factor and the measured value is higher than the second threshold measured value, output of AC power is stopped. Thereby, abnormality of a DC / AC conversion part can be controlled more suitably.

  In particular, in the situation where the measured values are the same, the power loss in the DC / AC converter is smaller when the power factor is equal to or higher than the threshold power factor than when the power factor is lower than the threshold power factor. In this regard, according to this configuration, the second threshold measurement value set when the power factor is relatively high is set higher than the first threshold measurement value set when the power factor is relatively low. . As a result, in a situation where the power factor is equal to or higher than the threshold power factor, it is possible to prevent the AC power output from being stopped even if the power loss in the DC / AC converter is relatively small.

  A non-contact power transmission apparatus that achieves the above object includes a DC / AC conversion unit that converts DC power into AC power having a predetermined frequency, and a voltage source that outputs the AC power, and the AC power is input. Primary side coil, secondary side coil capable of receiving the AC power input to the primary side coil in a non-contact manner, input voltage value or output voltage value of the DC / AC converter, power The output of the AC power from the voltage source is stopped or the power value of the AC power is reduced based on the rate or the current difference between the input current value and the output current value of the DC / AC converter. And a control unit.

  According to such a configuration, the output of AC power is stopped based on the input voltage value or output voltage value of the DC / AC converter and the current difference between the power factor or the input current value and output current value of the DC / AC converter. Etc. are performed. As a result, for example, when the power loss of the DC / AC converter is excessively large due to the power factor being excessively low in a situation where the input voltage value or the output voltage value is normal, the AC power Can be stopped, and the abnormality of the DC / AC converter can be avoided through the output. Therefore, the abnormality of the DC / AC converter can be suitably suppressed.

  In particular, in a configuration in which a voltage source is used as an AC power supply, an input voltage value or an output voltage value of a DC / AC conversion unit is employed as a parameter for determining whether output of AC power is stopped. The input voltage value and the output voltage value are not easily affected by fluctuations in the input impedance of the primary side coil. Thereby, even if the input impedance of the primary side coil fluctuates due to a change in the relative position between the primary side coil and the secondary side coil, it is possible to suitably stop the output of the AC power. .

  According to this invention, the abnormality of the DC / AC conversion unit can be suitably suppressed.

The block circuit diagram which shows the electric constitution of power transmission equipment and a non-contact electric power transmission apparatus. The flowchart which shows the stop control process performed with a power transmission side controller. The graph which shows a stop area. The graph which shows typically the relationship between an output voltage value and a power factor. The block circuit diagram which shows the power transmission apparatus of another example. The flowchart which shows the stop control process of another example. The graph which shows the stop area | region of another example.

Hereinafter, an embodiment of a power transmission device (power transmission device) and a non-contact power transmission device (non-contact power transmission system) will be described.
As shown in FIG. 1, the non-contact power transmission device 10 includes a power transmission device 11 (ground side device, primary side device) and a power receiving device 21 (vehicle side device, secondary side device) capable of non-contact power transmission. It has. The power transmission device 11 is provided on the ground, and the power receiving device 21 is mounted on the vehicle.

  The power transmission device 11 includes a voltage source 12 as an AC power source capable of outputting AC power having a predetermined frequency. The voltage source 12 is configured to be able to convert the grid power to AC power and output the converted AC power when grid power as external power is input from the grid power supply E as infrastructure.

  Specifically, the voltage source 12 receives an AC / DC converter 12a as a conversion unit that converts system power input from the system power supply E into DC power, and DC power output from the AC / DC converter 12a. A DC / AC converter 12b (DC / AC converter) that converts the DC power into AC power and outputs the converted AC power.

  The AC / DC converter 12a includes, for example, a switching element 12aa and a driver circuit 12ab that operates the switching element 12aa. The AC / DC converter 12a outputs DC power by the driver circuit 12ab periodically turning on / off the switching element 12aa. Incidentally, the AC / DC converter 12a is configured such that the power value of the output DC power is variable (changeable) by the driver circuit 12ab variably controlling the ON / OFF duty ratio of the switching element 12aa. For this reason, the voltage source 12 can change (change) the power value of the AC power to be output.

  The DC / AC converter 12b is, for example, a class D amplifier. Specifically, the DC / AC converter 12b includes a first switching element Q1 and a second switching element Q2 connected in series with each other. Each switching element Q1, Q2 is, for example, an n-type power MOSFET. The drain of the first switching element Q1 is connected to the first output terminal (+ terminal) of the AC / DC converter 12a, and the source of the second switching element Q2 is the second output terminal of the AC / DC converter 12a. Connected to (-end). The source of the first switching element Q1 and the drain of the second switching element Q2 are connected, and the connection line is connected to the first output terminal of the DC / AC converter 12b. The source of the second switching element Q2 is connected to the second output terminal of the DC / AC converter 12b.

  According to this configuration, the switching elements Q1 and Q2 are alternately turned ON / OFF, so that AC power corresponding to the switching frequency of the switching elements Q1 and Q2 is output from the DC / AC converter 12b. Further, for example, when the first switching element Q1 is in the OFF state and the second switching element Q2 is in the ON state, or when both the switching elements Q1 and Q2 are in the OFF state, DC / AC conversion is performed. AC power is not output from the vessel 12b, that is, output of AC power is stopped.

  As shown in FIG. 1, the DC / AC converter 12b includes a driver circuit 12ba that operates each switching element Q1, Q2 individually. The driver circuit 12ba sets the operation mode of each switching element Q1, Q2 to an output mode in which AC power is output or a stop mode in which output of AC power is stopped.

  Each switching element Q1, Q2 has body diodes (parasitic diodes) D1, D2. The current related to the back electromotive force that can be generated when the operation mode of each switching element Q1, Q2 is the output mode is transmitted through each body diode D1, D2.

  The AC power output from the voltage source 12 is transmitted to the power receiving device 21 in a non-contact manner, and input to a load 22 provided in the power receiving device 21. Specifically, the non-contact power transmission apparatus 10 performs power transmission between the power transmission device 11 and the power reception device 21, and includes a power transmitter 13 provided in the power transmission device 11 and a power receiver provided in the power reception device 21. 23.

  The power transmitter 13 and the power receiver 23 have the same configuration, and both are configured to be capable of magnetic field resonance. Specifically, the power transmitter 13 has a resonance circuit including a primary side coil 13a and a primary side capacitor 13b connected in parallel to each other. The power receiver 23 has a resonance circuit including a secondary coil 23a and a secondary capacitor 23b connected in parallel to each other. The resonant frequencies of both resonant circuits are set to be the same.

  The connection line between the source of the first switching element Q1 and the drain of the second switching element Q2 is connected to the first input of the power transmitter 13 via the first output terminal of the DC / AC converter 12b and the impedance converter 30 described later. It is connected to the end (one end of the primary coil 13a). The source of the second switching element Q2 is connected to the second input end of the power transmitter 13 (the other end of the primary coil 13a) via the second output end of the DC / AC converter 12b and the impedance converter 30. ing. The AC power output from the DC / AC converter 12 b is input to the power transmitter 13 via the impedance converter 30.

  According to such a configuration, when AC power is input to the power transmitter 13 (primary coil 13a) in a situation where the relative position between the power transmitter 13 and the power receiver 23 is in a position where magnetic resonance can occur, The power receiver 23 (secondary coil 23a) performs magnetic field resonance. As a result, the power receiver 23 receives part of the energy from the power transmitter 13. That is, the power receiver 23 receives AC power from the power transmitter 13.

  Incidentally, the frequency of the AC power output from the voltage source 12 (the switching frequency of each of the switching elements Q1 and Q2) is such that power transmission is possible between the power transmitter 13 and the power receiver 23. 23 corresponding to the resonance frequency. For example, the frequency of AC power is set to be the same as the resonance frequency of the power transmitter 13 and the power receiver 23. However, the present invention is not limited thereto, and the frequency of the AC power and the resonance frequency of the power transmitter 13 and the power receiver 23 may be deviated within a range where power transmission is possible.

  The load 22 to which AC power received by the power receiver 23 is input includes, for example, a rectifier (AC / DC converter) and a vehicle battery to which DC power rectified by the rectifier is input. The AC power received by the power receiver 23 is used for charging the vehicle battery.

  Incidentally, the impedance of the vehicle battery varies according to the power value of the input DC power. For this reason, the load 22 is a fluctuating load that varies according to the power value of the input AC power.

The power transmission device 11 includes a power transmission side controller 14 that controls the driver circuit 12ab of the AC / DC converter 12a, the driver circuit 12ba of the DC / AC converter 12b, and the like.
Specifically, when starting the output of AC power, the power transmission side controller 14 includes power value information that is information on the power value of DC power for the driver circuit 12ab of the AC / DC converter 12a. The output instruction signal is transmitted. Based on the output instruction signal, the driver circuit 12ab of the AC / DC converter 12a periodically turns on / off the switching element 12aa at a duty ratio corresponding to the power value information. Thereby, the direct current power of the power value information is output from the AC / DC converter 12a.

  On the other hand, the power transmission side controller 14 transmits a stop instruction signal to the driver circuit 12ab of the AC / DC converter 12a when stopping the output of the AC power. Based on the reception of the stop instruction signal, the driver circuit 12ab of the AC / DC converter 12a sets the switching element 12aa to a state where DC power is not output from the AC / DC converter 12a (for example, an OFF state).

  Further, the power transmission side controller 14 instructs the driver circuit 12ba of the DC / AC converter 12b to have a pulse signal having a frequency that is the same as or close to the resonance frequency of the power transmission device 13 and the power reception device 23, and an instruction signal that instructs an operation mode. And send. When the operation mode instructed by the instruction signal is the output mode, the driver circuit 12ba of the DC / AC converter 12b alternately turns on / off the switching elements Q1 and Q2 at the frequency of the input pulse signal. Let On the other hand, when the operation mode instructed by the instruction signal is the stop mode, the driver circuit 12ba of the DC / AC converter 12b turns, for example, the first switching element Q1 into the OFF state and the second switching element Q2 Is turned on, or both switching elements Q1 and Q2 are turned off.

  The power receiving device 21 includes a power receiving side controller 24 configured to be capable of wireless communication with the power transmitting side controller 14. The non-contact power transmission device 10 starts or ends power transmission through the exchange of information performed between the controllers 14 and 24.

  As illustrated in FIG. 1, the power transmission device 11 includes an impedance converter 30 that is provided between a voltage source 12 (specifically, a DC / AC converter 12 b) and a power transmitter 13 and performs impedance conversion. The impedance converter 30 is composed of, for example, a transformer or an LC circuit.

  Here, one load from the input end of the impedance converter 30 (the output end of the DC / AC converter 12b) to the load 22 is defined as one power source load. In this case, the impedance converter 30 causes the power factor λ with respect to the power supply load to approach “1” (preferably coincide) when AC power having a predetermined specific power value Pt is output from the voltage source 12. The input impedance of the power transmitter 13 is impedance-converted. In other words, the impedance (constant) of the impedance converter 30 is such that the power factor λ approaches (preferably matches) the power factor λ when the AC power having the specific power value Pt is output from the voltage source 12. Is set. That is, the impedance converter 30 of this embodiment is a power factor correction circuit. The power factor λ corresponds to the phase difference between the output voltage and the output current of the DC / AC converter 12b (voltage source 12). When the power factor λ approaches “1”, the phase difference Is equivalent to approaching “0”.

  Incidentally, the power transmission side controller 14 transmits the output instruction signal including the power value information of the specific power value Pt to the driver circuit 12ab of the AC / DC converter 12a, and outputs the output mode instruction signal and the pulse signal to the DC. The AC power of the specific power value Pt is output from the voltage source 12 by transmitting to the driver circuit 12ba of the / AC converter 12b.

  The power supply load impedance Zin, which is the input impedance of the impedance converter 30, depends on the input impedance of the power transmitter 13 (primary coil 13a). The input impedance of the power transmitter 13 varies according to the relative position of the power transmitter 13 and the power receiver 23 and also varies according to the impedance of the load 22.

  In such a configuration, when the relative position between the power transmitter 13 and the power receiver 23 is a predetermined reference position and the AC power having the specific power value Pt is output from the voltage source 12, the power factor λ is “1”. The power supply load impedance Zin approaching is set as a specific input impedance Zt. In this case, the impedance of the impedance converter 30 is such that the relative position of the power transmitter 13 and the power receiver 23 is the reference position, and the specific power value from the voltage source 12 so that the power load impedance Zin becomes the specific input impedance Zt. It can be said that it is set corresponding to the input impedance of the power transmitter 13 when the Pt AC power is output. In addition, it can be said that the voltage source 12 is configured to be able to output AC power having a specific power value Pt when the power load impedance Zin is the specific input impedance Zt.

  Here, when the power factor λ is low (bad), the power loss (burden) of the DC / AC converter 12b (specifically, each switching element Q1, Q2) increases. For this reason, even if the output voltage value Vout of the DC / AC converter 12b is a normal value, if the power factor λ is excessively low, the power loss of each switching element Q1, Q2 becomes excessively large, An abnormality may occur in the DC / AC converter 12b.

  On the other hand, the power transmission device 11 (non-contact power transmission device 10) of the present embodiment has a configuration for suppressing the abnormality of the DC / AC converter 12b. The configuration will be described in detail below.

  As illustrated in FIG. 1, the power transmission device 11 includes an output voltage value measurement unit 31 as a measurement unit that measures the output voltage value Vout of the DC / AC converter 12b, and a power factor detection unit 32 that detects the power factor λ. It has. The power factor detector 32 measures the input current value Iin of the DC / AC converter 12b and the output current value Iout of the DC / AC converter 12b, and detects (calculates) the power factor λ from the two values. . Specifically, the power factor λ is a quotient (Iin / Iout) of the input current value Iin with respect to the output current value Iout. The output current value Iout is, for example, an effective value. The output voltage value Vout and the output current value Iout can also be said to be an input voltage value and an input current value of the impedance converter 30 (power supply load).

  As illustrated in FIG. 1, the output voltage value measurement unit 31 transmits information on the measured output voltage value Vout to the power transmission side controller 14. Similarly, the power factor detection unit 32 transmits information regarding the detected power factor λ to the power transmission side controller 14.

  When AC power is output from the voltage source 12, the power transmission side controller 14 periodically performs stop control processing for performing stop control of output of the AC power based on the output voltage value Vout and the power factor λ. Running to. The stop control process will be described in detail below.

  As shown in FIG. 2, first, in step S <b> 101, the power transmission side controller 14 grasps the current power factor λ and output voltage value Vout from the detection result of the power factor detection unit 32 and the measurement result of the output voltage value measurement unit 31. To do.

  Thereafter, in step S <b> 102, the power transmission side controller 14 determines whether or not the output voltage value Vout is equal to or higher than the rated voltage value Vr of the voltage source 12. The power transmission side controller 14 proceeds to step S105 when the output voltage value Vout is greater than or equal to the rated voltage value Vr, while proceeds to step S103 when the output voltage value Vout is less than the rated voltage value Vr.

In step S103, the power transmission side controller 14 determines whether or not the output voltage value Vout is higher than a threshold voltage value Vth as a predetermined threshold measurement value.
The threshold voltage value Vth is an allowable voltage value corresponding to the minimum value of the power factor λ assumed when the power transmitter 13 and the power receiver 23 are positioned, for example. The allowable voltage value is an upper limit value of the output voltage value Vout at which the DC / AC converter 12b can normally operate or a value lower than the upper limit value by a predetermined margin. Specifically, the allowable voltage value is the upper limit value of the output voltage value Vout at which the temperature of the voltage source 12 (specifically, each switching element Q1, Q2) does not exceed the rated temperature, or a predetermined margin with respect to the upper limit value. It is a low value. The allowable voltage value is a parameter that depends on the power factor λ, and decreases as the power factor λ decreases. The threshold voltage value Vth is lower than the rated voltage value Vr and lower than the voltage value Vt when the AC power having the specific power value Pt is output.

  The time of positioning is, for example, a stage before starting output of AC power having a specific power value Pt, and in a state where AC power having a power value smaller than the specific power value Pt is output from the voltage source 12, the power receiver 23. In this step, the relative position between the power transmitter 13 and the power receiver 23 is determined based on the AC power received at.

  When the output voltage value Vout is higher than the threshold voltage value Vth, the power transmission side controller 14 determines whether or not the power factor λ is lower than the predetermined threshold power factor λth in step S104. The threshold power factor λth is the minimum value of the power factor λ that is allowed when AC power having the specific power value Pt is output. The threshold power factor λth is higher than the minimum value of the power factor λ assumed when the power transmitter 13 and the power receiver 23 are positioned.

  When the power factor λ is lower than the threshold power factor λth, the power transmission side controller 14 proceeds to step S105, executes an output stop process for stopping the output of the AC power, and ends the stop control process. Specifically, the power transmission-side controller 14 transmits a stop instruction signal to the driver circuit 12ab of the AC / DC converter 12a, and sends a stop mode instruction signal to the driver circuit 12ba of the DC / AC converter 12b. Send. That is, when the output voltage value Vout is higher than the threshold voltage value Vth and the power factor λ is lower than the threshold power factor λth (step S103: YES, step S104: YES), the power transmission-side controller 14 The output of is stopped. Further, when the output voltage value Vout is equal to or higher than the rated voltage value Vr, the power transmission side controller 14 stops the output of AC power regardless of the power factor λ.

  On the other hand, the power transmission side controller 14 has the power factor λ even when the output voltage value Vout is equal to or lower than the threshold voltage value Vth (step S103: NO), or when the output voltage value Vout is higher than the threshold voltage value Vth. If it is equal to or greater than the threshold power factor λth (step S103: YES, step S104: NO), the process proceeds to step S106. In step S106, the power transmission side controller 14 performs the output continuation process which continues the output of AC power without changing the power value, and ends the stop control process.

Next, the effect | action of this embodiment is demonstrated using FIG.
As indicated by the one-dot chain line in FIG. 3, (A) the output voltage value Vout is equal to or higher than the rated voltage value Vr, or (B) the power factor λ is lower than the threshold power factor λth and the output voltage value Vout. The region where is higher than the threshold voltage value Vth is a stop region A1 where the output of AC power stops. On the other hand, when the output voltage value Vout is less than the rated voltage value Vr and the power factor λ is greater than or equal to the threshold power factor λth or the output voltage value Vout is less than or equal to the threshold voltage value Vth, the power value is changed. AC power output continues.

According to the embodiment described above in detail, the following effects are obtained.
(1) A power transmission device 11 including a voltage source 12 having a DC / AC converter 12b that converts DC power into AC power, and a power transmitter 13 (primary coil 13a) to which AC power is input. Based on the output voltage value Vout and the power factor λ of the DC / AC converter 12b, the power transmission side controller 14 for stopping the output of the AC power is provided. Specifically, the power transmission device 11 includes an output voltage value measurement unit 31 that measures the output voltage value Vout and a power factor detection unit 32 that detects the power factor λ. Then, the power transmission side controller 14 determines that the output voltage value Vout measured by the output voltage value measuring unit 31 is higher than the threshold voltage value Vth, and the power factor λ detected by the power factor detecting unit 32 is the threshold power factor λth. If it is lower than that, the output of AC power is stopped. Thereby, even if the output voltage value Vout is a normal value, an excessive power loss of the DC / AC converter 12b that can occur due to the low power factor λ can be suppressed.

  Here, it is also conceivable to stop the output of the AC power based on the output current value Iout and the output power value Pout of the DC / AC converter 12b. However, the output current value Iout and the output power value Pout as described above depend on the power load impedance Zin (input impedance of the power transmitter 13). The power load impedance Zin varies depending on the relative position of the power transmitter 13 and the power receiver 23, the impedance of the load 22, and the like. For this reason, since the output current value Iout and the output power value Pout change due to the change in the relative position, the change in the impedance of the load 22, and the like, the output stop of the AC power is stopped based on the output current value Iout or the output power value Pout. If it is going to perform, the problem that the setting of a threshold current value and a threshold power value becomes complicated may arise. In addition, an inconvenience that erroneous output of AC power is stopped may occur due to the change in the relative position.

  On the other hand, according to the present embodiment, the output voltage value Vout that is a constant value regardless of the fluctuation of the power load impedance Zin is adopted as a parameter for determining the output stop of the AC power. Thereby, each inconvenience as described above can be avoided. Therefore, the abnormality of the DC / AC converter 12b can be suppressed more suitably.

  (2) Even if the power factor λ is lower than the threshold power factor λth, the power transmission side controller 14 does not change the power value if the output voltage value Vout is equal to or lower than the threshold voltage value Vth. Continue power output. Even when the power factor λ is lower than the threshold power factor λth, if the output voltage value Vout is equal to or lower than the threshold voltage value Vth, the power loss of the DC / AC converter 12b is relatively small. In this regard, according to the present configuration, in the above case, the output of AC power is continued without changing the power value. Thereby, it is possible to prevent the AC power output from being stopped even though the power loss of the DC / AC converter 12b is relatively small (normal value). The situation where the power loss of the DC / AC converter 12b is relatively small can be said to be a situation where the DC / AC converter 12b operates normally.

  Further, according to this configuration, it is possible to cope with a transient phenomenon of the power factor λ. The effect will be described in detail with reference to FIG. FIG. 4 is a graph schematically showing how the output voltage value Vout and the power factor λ change after the power transmission side controller 14 instructs the output of the AC power having the specific power value Pt. In FIG. 4, the power factor λ and the output voltage value Vout at each timing t1 to t5 are plotted. In the following description and FIG. 4, for the sake of simplicity of description and illustration, it is assumed that the rising characteristic of the output voltage value Vout and the rising characteristic of the output current value Iout are the same.

  As shown in FIG. 4, when an instruction to output AC power having a specific power value Pt is issued from the power transmission side controller 14 to each of the driver circuits 12ab and 12ba, the time elapses (t1 → t2 →... → t5). The output voltage value Vout gradually increases.

  Here, as already described, the impedance converter 30 of the power transmission device 11 is configured such that the power factor λ approaches “1” when the AC power having the specific power value Pt is output from the voltage source 12. Yes. For this reason, the power factor λ is low when the output voltage value Vout (output power value Pout) is low, that is, when a sufficient time has not elapsed from the output instruction timing from the power transmission side controller 14, and the output voltage value Vout ( The output power value Pout) increases as the value increases. Therefore, if the power factor λ is lower than the threshold power factor λth, the output voltage value Vout corresponds to the specific power value Pt when the output of the AC power is stopped regardless of the output voltage value Vout. Before reaching the value Vt, there arises a disadvantage that the output of the AC power is stopped.

  On the other hand, in this embodiment, even if the power factor λ is lower than the threshold power factor λth, if the output voltage value Vout is equal to or lower than the threshold voltage value Vth, the AC value is not changed. The power output continues. Thereby, the inconvenience can be avoided.

  (3) When the power factor λ is equal to or greater than the threshold power factor λth, the power transmission side controller 14 continues to output AC power on condition that the output voltage value Vout is less than the rated voltage value Vr. Thereby, electric power can be efficiently input with respect to a power supply load.

In addition, you may change the said embodiment as follows.
In the process of step S103 of the embodiment, the output voltage value Vout is used, but is not limited thereto. For example, as illustrated in FIG. 5, the power transmission device 11 may include an input voltage value measurement unit 41 that measures the input voltage value Vin of the DC / AC converter 12 b instead of the output voltage value measurement unit 31. . The input voltage value measurement unit 41 transmits the measured input voltage value Vin to the power transmission side controller 14. In step S103, the power transmission side controller 14 determines whether or not the input voltage value Vin measured by the input voltage value measuring unit 41 is higher than a predetermined threshold voltage value Vth. Even in this case, the above-described effects (1) and the like are exhibited. Moreover, in this example, since the input voltage value measurement part 41 measures DC voltage, it can become a comparatively simple structure rather than the output voltage value measurement part 31 which measures AC voltage. Thereby, simplification of a structure can be achieved.

  In short, the power transmission device 11 includes a measurement unit that measures the input voltage value Vin or the output voltage value Vout of the DC / AC converter 12b, and the power transmission controller 14 measures the measurement value and the threshold value measured by the measurement unit. What is necessary is just to compare with a value.

  In the process of step S104 of the embodiment, the power factor λ is used, but is not limited thereto. For example, a current difference between the input current value Iin and the output current value Iout may be used instead of the power factor λ. In this case, the power transmission device 11 may include a current difference detection unit that detects the current difference instead of (or in addition to) the power factor detection unit 32. In step S104, the power transmission side controller 14 determines whether the current difference detected by the current difference detection unit is larger than a predetermined threshold current difference. When the current difference is larger than the threshold current difference, the power transmission side controller 14 executes the output stop process in step S105, while when the current difference is equal to or smaller than the threshold current difference, the output continues in step S106. Execute the process.

  In addition, the power transmission device 11 may include a phase difference detection unit that detects the phase difference itself between the output voltage and the output current of the DC / AC converter 12b instead of the power factor detection unit 32. In this case, in step S104, the power transmission side controller 14 may determine whether or not the phase difference is larger than a predetermined threshold phase difference (for example, a phase difference corresponding to the threshold power factor λth).

  In short, in the determination process in step S104, the physical quantity relating to the phase difference between the output voltage and the output current of the DC / AC converter 12b, more specifically, the phase difference is relatively easy to fluctuate (the fluctuation amount is large). In addition, other parameters (for example, the output power value Pout) may be parameters that are less likely to vary (small variation).

  O The power transmission side controller 14 may perform the process which makes the electric power value of alternating current power small instead of the output stop process of step S105. Specifically, for example, the power transmission controller 14 may transmit an output instruction signal including power value information in which a power value smaller than the current output power value Pout is set to the driver circuit 12ab of the AC / DC converter 12a. Even in this case, the power loss of the DC / AC converter 12b can be reduced.

  In the embodiment, when the power factor λ is equal to or greater than the threshold power factor λth, if the output voltage value Vout is less than the rated voltage value Vr, the output of AC power is continued without changing the power value. However, it is not limited to this. For example, as shown in FIG. 6, the threshold voltage value Vth used in the determination process in step S103 is set as a first threshold voltage value Vth1 (first threshold measurement value). If the power transmission side controller 14 makes a negative determination in step S104, it determines in step S201 whether or not the output voltage value Vout is higher than the second threshold voltage value Vth2 (second threshold measurement value). . The second threshold voltage value Vth2 is set higher than the first threshold voltage value Vth1. For example, the first threshold voltage value Vth1 is set to an allowable voltage value when the power factor λ is “0”, while the second threshold voltage value Vth2 is set when the power factor λ is the threshold power factor λth. The allowable voltage value is set. The power transmission side controller 14 proceeds to step S105 when the output voltage value Vout is higher than the second threshold voltage value Vth2, while proceeds to step S106 when the output voltage value Vout is equal to or less than the second threshold voltage value Vth2. .

  According to such a configuration, as shown in FIG. 7, the stop area A2 of this different example is wider than the stop area A1 of the embodiment. Specifically, when the power factor λ is equal to or greater than the threshold power factor λth and the output voltage value Vout is higher than the second threshold voltage value Vth2, the output of AC power is stopped. Thereby, abnormality of DC / AC converter 12b can be controlled more suitably.

  In particular, since the second threshold voltage value Vth2 is set higher than the first threshold voltage value Vth1, when the output voltage value Vout is higher than the first threshold voltage value Vth1, the AC power is used regardless of the power factor λ. Compared with the configuration in which the output of the first AC power is stopped, the output of the first AC power is easily continued. Therefore, it is possible to more appropriately suppress unnecessary output stop of AC power.

  In this alternative example, the power transmission side controller 14 first executes the process of step S104 after making a negative determination in step S102. If the determination in step S104 is affirmative, the power transmission side controller 14 executes the process of step S103. If the determination in step S104 is negative, the process in step S201 may be executed. In this example, the process of step S102 may be omitted.

  In the description of the effect of (2), it is assumed that the rising characteristic of the output voltage value Vout and the rising characteristic of the output current value Iout are the same, but actually the rising time of the output voltage value Vout Is shorter than the rise time of the output current value Iout. The rise time of the output voltage value Vout is a time from when an output instruction of AC power having a desired power value is given until the output voltage value Vout becomes a voltage value corresponding to the desired power value. The rise time of the output current value Iout is the time from when the AC power output instruction of the desired power value is given until the output current value Iout becomes a current value corresponding to the desired power value.

  Focusing on this point, the threshold voltage value Vth and the threshold power factor λth may be set in consideration of the difference between the rise time of the output voltage value Vout and the rise time of the output current value Iout. For example, the threshold voltage value Vth may be set to be equal to or higher than the output voltage value Vout at a timing at which the power factor λ that rises based on the AC power output instruction becomes the threshold power factor λth. Thereby, when the AC power having a desired power value (for example, the specific power value Pt) is output from the voltage source 12, the output voltage value Vout is the threshold value at a timing before the power factor λ becomes equal to or higher than the threshold power factor λth. It can avoid becoming higher than voltage value Vth. Further, the power transmission side controller 14 may be configured to compare the power factor λ and the threshold power factor λth after the standby period has elapsed since the AC power output instruction was issued. In this case, the standby period may be a period from when the AC power output instruction is given until the power factor λ becomes the threshold power factor λth. The “alternating power output instruction” can also be said to be the operation start of the voltage source 12 (AC / DC converter 12a and DC / AC converter 12b).

The output voltage value measurement unit 31 and the power factor detection unit 32 may be mounted on the power transmission side controller 14.
○ DC power having a predetermined power value may be input as external power. In this case, the AC / DC converter 12a may be omitted, or a DC / DC converter may be provided instead of the AC / DC converter 12a. In this example, the DC / DC converter corresponds to the conversion unit.

A plurality of impedance converters 30 may be provided. Further, the impedance converter 30 may be omitted.
The specific configuration of the DC / AC converter 12b is arbitrary, and may be, for example, a class E amplifier having one switching element or a bridge circuit having four switching elements.

  The specific configuration of the AC / DC converter 12a is arbitrary, and may be a configuration in which the power value of DC power cannot be made variable. Further, the AC / DC converter 12a may be, for example, a step-up type or a step-up / step-down type.

  Each switching element Q1, Q2 is a power MOSFET, but is not limited thereto, and other switching elements such as IGBTs may be used. Further, instead of the body diodes D1 and D2, two diodes connected in parallel to the switching elements Q1 and Q2 may be separately provided.

A dead time during which both the switching elements Q1 and Q2 are turned off may be provided between ON / OFF switching of the switching elements Q1 and Q2.
○ The specific configuration for stopping the output of AC power is arbitrary. For example, a contactor is provided on the power transmission path before or after the AC / DC converter 12a, and the power transmission side controller 14 turns the contactor off from the ON state. It may be configured to switch to a state.

  The execution subject of the stop control process is not limited to the power transmission side controller 14 and may be arbitrary, for example, the power reception side controller 24. In this case, the power transmission side controller 14 may appropriately transmit information necessary for the stop control process to the power reception side controller 24. Moreover, the power receiving side controller 24 gives various instructions with respect to the power transmission side controller 14 as needed, and the power transmission side controller 14 performs DC / AC converter 12b, AC / DC converter 12a, etc. according to the said various instructions. Control is good.

The resonance frequency of the power transmitter 13 and the resonance frequency of the power receiver 23 are set to be the same. However, the present invention is not limited to this, and they may be different within a range where power transmission is possible.
The power transmitter 13 and the power receiver 23 have the same configuration, but are not limited to this, and may have different configurations.

Each capacitor 13b, 23b may be omitted. In this case, magnetic field resonance is performed using the parasitic capacitances of the coils 13a and 23a.
O The power receiving device 21 can be mounted on any object, for example, a robot or an electric wheelchair.

  In embodiment, although the primary side coil 13a and the primary side capacitor | condenser 13b were connected in parallel, it is not restricted to this, Both may be connected in series. Similarly, the secondary coil 23a and the secondary capacitor 23b may be connected in series.

In the embodiment, magnetic field resonance is used in order to realize non-contact power transmission. However, the present invention is not limited to this, and electromagnetic induction may be used.
The threshold voltage value Vth may be set to an allowable voltage value when the power factor λ is “0”, or set to an allowable voltage value when the power factor λ is the threshold power factor λth. Also good. In short, the threshold voltage value Vth and the threshold power factor λth suppress the occurrence of an abnormality in the voltage source 12, and the switching elements Q1, Q2 so that the output of AC power from the voltage source 12 can be easily continued. It may be set as appropriate based on the specifications.

In the embodiment, the AC power received by the power receiver 23 is used for charging the vehicle battery, but is not limited thereto, and may be used for other purposes.
The power transmitter 13 may include a resonance circuit including a primary side coil 13a and a primary side capacitor 13b, and a primary side coupling coil that is coupled to the resonance circuit by electromagnetic induction. Similarly, the power receiver 23 may include a resonance circuit including a secondary coil 23a and a secondary capacitor 23b, and a secondary coupling coil coupled to the resonance circuit by electromagnetic induction.

Next, a preferable example that can be grasped from the embodiment and another example will be described below.
(B) When the power factor is equal to or greater than the threshold power factor, the control unit continues to output the AC power from the voltage source without changing the power value. The power transmission equipment described in 1.

  (B) An impedance conversion unit that is provided between the voltage source and the primary side coil and performs impedance conversion, and the impedance conversion unit receives AC power having a predetermined specific power value from the voltage source. The power transmission apparatus according to any one of claims 1 to 4 and (A), wherein when the power is output, the input impedance of the primary coil is impedance-converted so that the power factor approaches 1.

  (C) The voltage source converts external power into DC power, and includes a conversion unit capable of changing the power value of the DC power. (A), (B) The power transmission apparatus as described in any one of these.

  (D) The DC / AC converter includes a first switching element and a second switching element connected in series with each other, and the first switching element and the second switching element are alternately turned ON / OFF, thereby The power transmission device according to any one of claims 1 to 4 and (A) to (C), which outputs AC power.

  DESCRIPTION OF SYMBOLS 10 ... Non-contact electric power transmission apparatus, 11 ... Power transmission apparatus, 12 ... Voltage source, 12a ... AC / DC converter, 12b ... DC / AC converter, 13a ... Primary side coil, 14 ... Power transmission side controller, 21 ... Power reception Equipment: 22 ... Load, 23a ... Secondary coil, 30 ... Impedance converter, 31 ... Output voltage value measurement unit, 32 ... Power factor detection unit, Q1, Q2 ... Switching element of DC / AC converter, λ ... Power Rate, λth ... threshold power factor, Vout ... output voltage value, Vth ... threshold voltage value.

Claims (5)

A voltage source having a DC / AC conversion unit for converting DC power into AC power having a predetermined frequency, and outputting the AC power;
A primary coil to which the AC power is input;
A power transmission device capable of transmitting the AC power in a non-contact manner with respect to the secondary side coil of a power receiving device having a secondary side coil,
The AC power from the voltage source based on the input voltage value or the output voltage value of the DC / AC converter and the power factor or the current difference between the input current value and the output current value of the DC / AC converter. A power transmission device comprising a control unit that stops the output of the power supply or reduces the power value of the AC power. A measurement unit for measuring the input voltage value or the output voltage value;
A power factor detector for detecting the power factor;
With
The control unit is configured such that the measurement value measured by the measurement unit is higher than a predetermined threshold measurement value, and the power factor detected by the power factor detection unit is higher than a predetermined threshold power factor. The power transmission device according to claim 1, wherein when the power is low, the output of the AC power from the voltage source is stopped, or the power value of the AC power is reduced.   Even if the power factor is lower than the threshold power factor, the control unit outputs the AC power without changing the power value when the measured value is equal to or less than the threshold measured value. The power transmission device according to claim 2 which continues. The threshold measurement is a first threshold measurement;
The control unit stops the output of the AC power from the voltage source when the power factor is equal to or higher than the threshold power factor and the measured value is higher than a predetermined second threshold measured value. Or to reduce the power value of the AC power,
The power transmission device according to claim 2 or 3, wherein the second threshold measurement value is set higher than the first threshold measurement value. A voltage source having a DC / AC conversion unit for converting DC power into AC power having a predetermined frequency, and outputting the AC power;
A primary coil to which the AC power is input;
A secondary coil capable of receiving the AC power input to the primary coil in a contactless manner;
The AC power from the voltage source based on the input voltage value or the output voltage value of the DC / AC converter and the power factor or the current difference between the input current value and the output current value of the DC / AC converter. A control unit for stopping the output of the AC power or reducing the power value of the AC power;
A non-contact power transmission device comprising: