JP6631116B2 - Power transmission device and contactless power supply system - Google Patents

Description

  The present invention relates to a power transmission device and a wireless power supply system.

  2. Description of the Related Art A non-contact power supply system that transmits power from a power transmission coil of a power transmission device to a power reception coil of a power reception device in a non-contact (wireless) manner and supplies power to a load on the power reception device side is known. In such a non-contact power supply system, the power supplied to the power receiving coil and eventually to the load changes due to the relative position of the power transmitting coil and the power receiving coil being shifted (position shift).

  For example, Patent Literature 1 discloses a method of detecting the above-described position shift, determining the frequency of AC power supplied to the power transmission coil in accordance with the detected position shift, and then performing power transmission.

JP 2012-191664 A

  In a contactless power supply system, there is a demand to supply a desired power to a load. However, if there is a relative displacement between the power transmitting coil and the power receiving coil, the power supplied to the load changes accordingly. In order to bring the power supplied to the load closer to the desired power, for example, as in the method of Patent Document 1, a position shift is detected, and the frequency of the AC power supplied to the power transmission coil is controlled according to the detected position shift. In addition, it takes time and effort to detect the displacement.

  The present invention provides a power transmission device and a contactless power supply system capable of adjusting power supplied to a load without detecting a position shift.

  A power transmission device according to one aspect of the present invention is a power transmission device for supplying power to a power reception device connected to a load, the power transmission device being a first coil, and transmitting power to a second coil of the power reception device in a non-contact manner. A first coil for converting the AC power into AC power after receiving the power, and supplying the converted AC power to the first coil; and a controller for changing a parameter for controlling the AC power. . The controller determines a parameter based on a power change rate indicating a change amount of the power supplied to the load with respect to a predetermined change amount of the parameter from the reference value so that the power supplied to the load approaches a desired power. To change.

  In the above power transmission device, the power supplied to the load approaches the desired power based on a power change rate indicating a change amount of the power supplied to the load with respect to a predetermined change amount of the parameter from the reference value. , The parameters are changed. Since the parameter is changed based on the power change rate in this manner, the power supplied to the load can be adjusted to approach the desired power without detecting a position shift.

  The controller may store the power change rate. Thus, for example, since it is not necessary to determine the power change rate in real time, the responsiveness of adjusting the power supplied to the load can be improved accordingly.

  The controller may acquire the power change rate from outside the power transmission device. For example, the power change rate is acquired by receiving the power change rate transmitted from another device (for example, a moving body such as a car) provided with the power receiving device. In this case, since the moving object such as a car transmitting the power change rate knows the characteristics of the power receiving device, the power change rate corresponding to the power receiving device is acquired. Thereby, the power supplied to the load is adjusted based on the appropriate power change rate. Therefore, even when power is supplied to power receiving devices having different types and characteristics, the power supplied to the load can be appropriately adjusted.

  The controller may change the parameter based on a difference between the power supplied to the load and the desired power and a power change rate. In this case, for example, the power supplied to the load can be made closer to the desired power by changing the parameter by an amount corresponding to the difference between the power supplied to the load and the desired power.

  The parameter may be a frequency of the AC power, and the reference value may be a reference frequency defined for the frequency of the AC power. In other words, the controller determines that the power supplied to the load approaches the desired power based on the power change rate of the power supplied to the load with respect to a predetermined frequency change amount of the frequency of the AC power from the reference frequency. Alternatively, the parameters may be changed. As described above, by setting the parameter to, for example, the frequency of the AC power, the power supplied to the load can be adjusted to a value close to the desired power without detecting a position shift.

  The power change rate is set for each of the different reference frequencies, and the controller determines whether the power supplied to the load is desired based on the power change rate using the frequency of the AC power supplied to the first coil as the reference frequency. The frequency of the AC power may be changed so as to approach the power. Thus, even when the power change rate differs depending on the reference frequency, it is possible to change a parameter based on an appropriate power change rate corresponding to the frequency of the AC power supplied to the first coil. Therefore, the adjustment accuracy of the power supplied to the load can be improved.

  When different reference frequencies are arranged in ascending or descending order, the interval between adjacent reference frequencies may be set to be wider as the amount of change in the power change rate with respect to the frequency of the AC power is smaller. For example, if each reference frequency is set at equal intervals at a frequency interval at which an appropriate resolution can be obtained for the amount of change in the power change rate when the change amount of the power change rate is large, the power change rate is small in an area where the change amount of the power change rate is small. Resolution is too fine for quantity. In this case, the number of reference frequencies, that is, the number of corresponding power change rates becomes too large, and accordingly, the amount of data to be handled becomes unnecessarily large. On the other hand, if each reference frequency is set at equal intervals at a frequency interval at which an appropriate resolution for the change can be obtained with reference to a region where the change in the power change is small, the power change is large in a region where the change in the power change is large. The resolution for the quantity becomes coarse. In this case, there is a possibility that the power adjustment accuracy cannot be sufficiently increased. According to the above configuration, the interval between adjacent reference frequencies is set to be wider as the change amount of the power change rate is smaller. Therefore, in a region where the change amount of the power change rate is smaller, the change amount of the power change rate is smaller. The frequency interval is set so that the resolution with respect to is not too fine, and the data amount is suppressed. Further, in an area where the amount of change in the power change rate is large, the frequency interval is set so that the resolution for the amount of change in the power change rate does not become too coarse. Therefore, it is possible to maintain the adjustment accuracy of the power supplied to the load while reducing the amount of data to be handled.

  The power change rate is set for each of the different voltage ranges of the power supplied to the load, and the controller determines the power change rate based on the power change rate corresponding to the voltage range including the voltage of the power supplied to the load. The parameter may be changed so that the power supplied to the load approaches the desired power. Thereby, even when the power change rate varies depending on the voltage range of the power supplied to the load, it is possible to change the parameter based on the appropriate power change rate corresponding to the voltage of the power supplied to the load. . Therefore, the adjustment accuracy of the power supplied to the load can be improved.

  The controller calculates the control amount of the parameter based on the difference between the power supplied to the load and the desired power and the power change rate, and increases the power supplied to the load when increasing the power supplied to the load. The correction may be performed such that the magnitude of the control amount is reduced, and the parameter may be changed by the control amount of the corrected parameter. Thus, for example, it is possible to suppress that the power supplied to the load and the power flowing through the power transmission device and the like increase rapidly and it becomes difficult to stably adjust the power supplied to the load.

  The controller may estimate the power supplied to the load based on the AC power, and may change the parameters so that the estimated power approaches the desired power. Thus, since the power supplied to the load is estimated based on the AC power supplied to the first coil, for example, the power supplied to the load is detected on the power receiving device side, and the detection result is transmitted to the power transmitting device side. The power supplied to the load can be adjusted without employing such a configuration. Therefore, the possibility of simplifying the apparatus and reducing costs is increased.

  A non-contact power supply system according to another aspect of the present invention includes the above power transmission device and a power reception device, wherein the power reception device can communicate with the power transmission device, and the power reception device receives power supplied to a load. The controller of the power transmitting device includes a detector for detecting, and changes the parameter so that the power detected by the detector of the power receiving device approaches the desired power.

  According to this non-contact power supply system, since the above-described power transmission device is provided, it is possible to adjust the power supplied to the load without detecting the displacement between the first coil and the second coil. . In addition, the power supplied to the load is detected using the detector of the power receiving device, and the controller of the power transmitting device changes the parameter using the detection result, so that, for example, the AC power supplied to the first coil is changed. The adjustment accuracy of the power supplied to the load can be improved as compared with the case where the power supplied to the load is estimated based on the above.

  ADVANTAGE OF THE INVENTION According to this invention, it becomes possible to adjust the electric power supplied to a load, without detecting a displacement.

It is a figure showing an example of application of a power transmission device and a non-contact electric supply system concerning one embodiment. It is a circuit block diagram of the non-contact electric supply system concerning one embodiment. FIG. 4 is a diagram for describing power adjustment by frequency control. FIG. 9 is a diagram for describing an example of a data table creation method. FIG. 9 is a diagram for describing an example of a data table creation method. FIG. 9 is a diagram for describing an example of a data table creation method. FIG. 9 is a diagram for describing an example of a data table creation method. 5 is a flowchart illustrating an example of a process performed in the power transmission device. 9 is a flowchart illustrating another example of a process executed in the power transmission device. FIG. 2 is a diagram illustrating an example of a circuit configuration of a DC / AC converter.

  Hereinafter, embodiments according to the present invention will be described with reference to the drawings. When possible, the same parts are denoted by the same reference numerals, and redundant description will be omitted.

  FIG. 1 is a diagram illustrating an application example of a power transmission device and a wireless power supply system according to an embodiment. As shown in FIG. 1, the non-contact power supply system 1 includes a power transmission device 2 and a power reception device 3, and is a system for supplying power from the power transmission device 2 to the power reception device 3. The power transmitting device 2 and the power receiving device 3 are separated, for example, in the vertical direction. The power transmission device 2 is installed, for example, in a parking lot or the like. The power receiving device 3 is mounted on an electric vehicle EV. The non-contact power supply system 1 is configured to supply electric power to an electric vehicle EV arriving at a parking lot or the like by using magnetic coupling between coils of a magnetic resonance type or an electromagnetic induction type. The power receiving device 3 may be mounted not on the electric vehicle EV but on various moving objects such as a plug-in hybrid vehicle and an underwater vehicle.

  The power transmission device 2 is a device that supplies power for wireless power supply. The power transmitting device 2 generates a desired AC power from the power supplied by the power supply PS (see FIG. 2) and transmits the generated AC power to the power receiving device 3. The power transmission device 2 is installed on a road surface R such as a parking lot, for example. The power transmission device 2 includes a power transmission coil device 4 provided to protrude upward from a road surface R such as a parking lot. The power transmission coil device 4 includes the first coil 21 (see FIG. 2), and has, for example, a flat frustum shape or a rectangular parallelepiped shape. The power transmission device 2 generates desired AC power from an AC power supply. By transmitting the generated AC power to the power transmitting coil device 4, the power transmitting coil device 4 generates a magnetic flux.

  The power receiving device 3 is a device that receives power from the power transmitting device 2 and supplies power to the load L (see FIG. 2). The power receiving device 3 is mounted on, for example, an electric vehicle EV. The power receiving device 3 includes, for example, a power receiving coil device 5 attached to a bottom surface of a vehicle body (a chassis or the like) of the electric vehicle EV. The power receiving coil device 5 includes the second coil 31 (see FIG. 2), and faces the power transmitting coil device 4 while being separated vertically in power supply. The power receiving coil device 5 has, for example, a flat frustum shape or a rectangular parallelepiped shape. The magnetic flux generated in the power transmitting coil device 4 links with the power receiving coil device 5, so that the power receiving coil device 5 generates an induced current. Thereby, the power receiving coil device 5 receives the electric power from the power transmitting coil device 4 in a non-contact (that is, wireless) manner. The power received by the power receiving coil device 5 is supplied to the load.

  With reference to FIG. 2, the circuit configuration of the wireless power supply system 1 will be described in detail. FIG. 2 is a circuit block diagram of the wireless power supply system 1. As shown in FIG. 2, the non-contact power supply system 1 is a system that receives an input power P1 from a power supply PS and supplies a load L with load power Pout. The power supply PS may be an AC power supply or a DC power supply. The type of the AC power supply is not particularly limited, but may be, for example, a commercial power supply. The type of the DC power supply is not particularly limited, but may be, for example, a solar power generation device, a power storage device, or the like. The load L may be a DC load or an AC load. The type of DC load is not particularly limited, but may be, for example, a storage battery. The type of the AC load is not particularly limited, but may be, for example, a motor.

  The power transmission device 2 is supplied with input power P1 from a power supply PS. The power transmission device 2 includes a first coil 21, a first converter 22, a first detector 23, a first communicator 24, and a first controller 25.

  The first converter 22 is a circuit that converts the input power P1 supplied from the power supply PS into a desired AC power Pac2 and supplies the converted AC power Pac2 to the first coil 21. The first converter 22 includes a power converter 26 and a DC / AC converter 27.

  As the power converter 26, for example, the following configuration can be adopted according to the input power P1. When the input power P1 is AC power, the power converter 26 may be, for example, an AC / DC converter. The AC / DC converter is, for example, a rectifier circuit. The rectifier circuit may be constituted by a rectifier such as a diode, or may be constituted by a switching element such as a transistor. The DC / AC converter may have a PFC (Power Factor Correction) function and a step-up / step-down function.

  When the input power P1 is DC power, the power converter 26 may be, for example, a DC / DC converter. The DC / DC converter may be, for example, a non-insulated type circuit using a chopper circuit, or an insulated type circuit using a transformer.

  In any case, the magnitude of the DC power Pdc output from the power converter 26 is controlled by the first controller 25. The magnitude of the DC power Pdc is controlled, for example, by changing the DC voltage output from the power converter 26. The power converter 26 supplies the converted DC power Pdc to the DC / AC converter 27.

  DC / AC converter 27 converts DC power Pdc converted by power converter 26 into AC power Pac2. The DC / AC converter 27 is, for example, an inverter circuit. The first converter 22 may further include a transformer provided at an output of the DC / AC converter 27. The magnitude of the AC power Pac2 output from the DC / AC converter 27 is controlled by the first controller 25. The magnitude of the AC power Pac2 can be controlled by, for example, frequency control and phase shift control. The DC / AC converter 27 supplies the converted AC power Pac2 to the first coil 21.

  Note that the configuration of the first converter 22 is not limited to the example shown in FIG. For example, the first converter 22 may include an AC / AC converter instead of the power converter 26 and the DC / AC converter 27. The AC / AC converter is, for example, a matrix converter, a cycloconverter, or the like. In this case, the first converter 22 receives AC power from the power supply PS and converts it into AC power. Further, the power converter 26 may include an AC / DC converter and a DC / DC converter provided at an output of the AC / DC converter.

  The first coil 21 is a coil for supplying power to the power receiving device 3 in a non-contact manner. The first coil 21 generates a magnetic flux when the AC power Pac2 is supplied from the first converter 22. A capacitor and an inductor (for example, a reactor) may be connected between the first coil 21 and the first converter 22.

  First detector 23 includes a sensor for detecting the magnitude of DC power Pdc. The first detector 23 is, for example, a voltage sensor, a current sensor, or a combination thereof.

  The first communicator 24 is a circuit for wirelessly communicating with a second communicator 34 of the power receiving device 3 described below. The first communicator 24 is, for example, an antenna for a communication method using radio waves, a light emitting element and a light receiving element for a communication method using optical signals. The first communicator 24 outputs information received from the power receiving device 3 to the first controller 25.

  The first controller 25 is a processing device such as a CPU (Central Processing Unit) and a DSP (Digital Signal Processor). The first controller 25 may include a read only memory (ROM), a random access memory (RAM), and an interface circuit connected to each unit of the power transmission device 2. The first controller 25 controls the first converter 22 to control the magnitude of the AC power Pac2 and execute power control for controlling the magnitude of the load power Pout supplied to the load L. The first controller 25 performs power control, for example, based on a measured value and a power command value (described later) received from the power receiving device 3 via the first communication device 24 such that the measured value approaches the power command value. The first converter 22 is controlled.

  The power control is performed using at least one of frequency control, phase shift control, and control of DC power Pdc, which will be described below. In each control, a parameter for controlling the magnitude of the AC power Pac2 is changed.

  The frequency control will be described. The magnitudes of the AC power Pac2 and the load power Pout are changed according to the frequency of the AC power Pac2. As the frequency of the AC power Pac2, for example, 81.38 kHz to 90 kHz can be used. When the frequency changes, the impedance of the reactance elements such as the coil and the capacitor changes, and the magnitudes of the AC power Pac2 and the load power Pout change. Hereinafter, in the present embodiment, it is assumed that the AC power Pac2 and the load power Pout decrease as the frequency increases. The first controller 25 changes the frequency of the AC power Pac2 to perform frequency control for changing the magnitudes of the AC power Pac2 and the load power Pout. The above parameter in the frequency control is the frequency of the AC power Pac2. The frequency of the AC power Pac2 is the frequency of the AC current or the AC voltage output from the first converter 22.

  The specific method of frequency control is not limited. For example, when the DC / AC converter 27 is an inverter circuit, the first controller 25 adjusts the switching frequency of each switching element using a drive signal supplied to each switching element included in the inverter circuit. , The frequency of the AC power Pac2 is changed. The switching element is, for example, an FET (Field Effect Transistor), an IGBT (Insulated Gate Bipolar Transistor) or the like. In this case, a drive signal is applied to the gate of the switching element. The details of the frequency control will be further described later with reference to FIG.

  The phase shift control will be described. When the DC / AC converter 27 is an inverter circuit as shown in FIG. 10, the first controller 25 adjusts the supply time of the drive signals Sa to Sd to the switching elements a to d included in the inverter circuit. Then, the time when each of the switching elements a to d is turned on is adjusted. When the driving time of the switching element a and the driving time of the switching element d are the same, and the driving time of the switching element b and the driving time of the switching element c are the same, the energization period of the inverter circuit is the longest. The more the drive time of the switching element a and the drive time of the switching element d are shifted (the more the drive time of the switching element b is shifted from the drive time of the switching element c), the shorter the conduction period of the inverter circuit becomes. AC power Pac2 decreases as the period of current supply to the inverter circuit decreases. The above-mentioned parameter in the phase shift control is a deviation amount between the driving time of the switching element a and the driving time of the switching element d (or a deviation amount between the driving time of the switching element b and the driving time of the switching element c).

  Control of DC power Pdc will be described. In the control of the DC power Pdc, the magnitude of the voltage of the DC power Pdc is changed. The change of the voltage of the DC power Pdc is performed using, for example, the step-up / step-down function of the power converter 26 described above. For example, as the voltage of DC power Pdc increases, AC power Pac2 also increases, and as the voltage of DC power Pdc decreases, AC power Pac2 also decreases. Therefore, the above parameter in the control of the DC power Pdc is the magnitude of the voltage of the DC power Pdc.

  In this specification, an example in which frequency control is mainly used as power control will be described in detail. The phase shift control and the control of the DC power Pdc can be described on the same principle as the frequency control. In addition, hereinafter, the frequency of the AC power Pac2 may be referred to as “drive frequency f”. The change amount of the drive frequency f that is changed (controlled) by the frequency control may be referred to as “frequency control amount Δf”.

  The power receiving device 3 includes a second coil 31, a second converter 32, a second detector 33, a second communicator 34, and a second controller 35.

  The second coil 31 is a coil for receiving electric power supplied from the power transmission device 2 in a non-contact manner. When the magnetic flux generated by the first coil 21 interlinks with the second coil 31, AC power Pac3 is generated in the second coil 31. The second coil 31 supplies the AC power Pac3 to the second converter 32. A capacitor and an inductor (for example, a reactor) may be connected between the second coil 31 and the second converter 32.

  The second converter 32 is a circuit that converts the AC power Pac3 received by the second coil 31 into a load power Pout desired for the load L. When the load L is a DC load, the second converter 32 is an AC / DC converter (rectifier circuit) that converts the AC power Pac3 into the DC load power Pout. In this case, the second converter 32 may include a step-up / step-down function to output a load power Pout desired for the load L. This step-up / step-down function can be realized by, for example, a chopper circuit or a transformer. The second converter 32 may further include a transformer provided at an input of the AC / DC converter.

  When the load L is an AC load, the second converter 32 further includes a DC / AC converter (an inverter circuit) in addition to the AC / DC converter that converts the AC power Pac3 into DC power. The DC / AC converter converts the DC power converted by the AC / DC converter into AC load power Pout. The second converter 32 may further include a transformer provided at an input of the AC / DC converter. If the AC power Pac3 supplied from the second coil 31 is a desired AC power for the load L, the second converter 32 may be omitted.

  The second detector 33 acquires a measurement value regarding the load power Pout supplied to the load L. The second detector 33 measures a load voltage, a load current, or a load power Pout supplied to the load L. The second detector 33 is, for example, a voltage sensor, a current sensor, or a combination thereof. The second detector 33 outputs the obtained measurement value to the second controller 35. The load L outputs a power command value to the second controller 35. The power command value indicates the magnitude of desired power to be supplied to the load L. For example, when the load L is a storage battery, the power command value may be a current, voltage, or power command value determined according to the SOC (State Of Charge) of the load L.

  The second communication device 34 is a circuit for performing wireless communication with the first communication device 24 of the power transmission device 2. The power receiving device 3 can communicate with the power transmitting device 2 by the second communication device 34. The second communicator 34 is, for example, an antenna for a communication method using radio waves, a light emitting element and a light receiving element for a communication method using optical signals. The second communicator 34 transmits the information received from the second controller 35 to the power transmitting device 2.

  The second controller 35 is a processing device such as a CPU and a DSP. The second controller 35 may include a ROM, a RAM, an interface circuit connected to each unit of the power receiving device 3, and the like. The second controller 35 transmits the measured value received from the second detector 33 and the power command value received from the load L to the power transmission device 2 via the second communication device 34.

  Note that, for example, by connecting a storage battery of an electric vehicle to the power transmission device 2 instead of the power supply PS, and connecting the power reception device 3 to the power supply PS instead of the load L, the power transmission device 2 transmits power from the power reception device 3 to the power transmission device 2. Can also be transmitted.

  Next, the details of the frequency control by the first controller 25 of the power transmission device 2 will be described with reference to FIG.

  The horizontal axis of the graph of FIG. 3 indicates frequency, and the vertical axis indicates power (magnitude). The frequency is the above-described drive frequency f, that is, the frequency of the AC power Pac2 supplied to the first coil 21. The power is the above-described load power Pout, that is, the power supplied to the load L.

  The characteristic (hereinafter, sometimes simply referred to as “power characteristic”) indicating the relationship between the driving frequency f and the load power Pout shown in the graph of FIG. 3 depends on the coupling coefficient k between the first coil 21 and the second coil 31. Can change. The coupling coefficient k changes according to, for example, the relative positional relationship between the first coil 21 and the second coil 31. For example, when a positional shift occurs due to a change in the positional relationship between the first coil 21 and the second coil 31, the coupling coefficient k changes. In general, the displacement is a displacement from the position of the first coil 21 and the position of the second coil 31 at which the coupling coefficient k is maximized. For this reason, the coupling coefficient k decreases as the displacement increases. As a power characteristic at different coupling coefficients k, the graph of FIG. 3 shows two curves, a curve C1 and a curve C2.

  In the graph of FIG. 3, as the power characteristics indicated by the curves C1 and C2, an example in which the load power Pout decreases as the drive frequency f increases as described above is shown. Specifically, a method of adjusting the load power Pout by changing the drive frequency f will be described.

  For example, in the power characteristic shown by the curve C1, it is assumed that the driving frequency f is initially the frequency fb1. The load power Pout at this time is the power Pb. Here, for example, the drive frequency f is reduced from the frequency fb1 to the frequency fa1 (that is, the frequency control amount Δf = fa1−fb1). Then, the load power Pout becomes the power Pa corresponding to the drive frequency f = fa1. Therefore, the load power Pout increases from the power Pb to the power Pa.

  On the other hand, when decreasing the load power Pout, for example, the drive frequency f is increased from the frequency fb1 to the frequency fc1 (that is, the frequency control amount Δf = fc1−fb1). Then, the load power Pout becomes the power Pc corresponding to the drive frequency f = fc1. Therefore, the load power Pout decreases from the power Pb to the power Pc.

  The same applies to the power characteristic indicated by the curve C2. That is, it is initially assumed that the driving frequency f is the frequency fb2. The load power Pout at this time is the power Pb. Here, for example, the drive frequency f is reduced from the frequency fb2 to the frequency fa2 (that is, the frequency control amount Δf = fa2−fb2). Then, the load power Pout becomes the power Pa corresponding to the drive frequency f = fa2. Therefore, the load power Pout increases from the power Pb to the power Pa.

  On the other hand, when decreasing the load power Pout, for example, the drive frequency f is increased from the frequency fb2 to the frequency fc2 (that is, the frequency control amount Δf = fc2-fb2). Then, the load power Pout becomes the power Pc corresponding to the drive frequency f = fc2. Therefore, the load power Pout decreases from the power Pb to the power Pc.

  For example, by controlling the driving frequency f as described above, the load power Pout can be made closer to desired power (power Pa, Pc, etc.). Further, as described below, it is also possible to suppress a change in the load power Pout when the coupling coefficient k changes.

  That is, as described above, the coupling coefficient k between the first coil 21 and the second coil 31 can change depending on the positional relationship between the two. For example, in the example shown in FIG. 1, when non-contact power supply is performed to the electric vehicle EV, if the occupant gets on and off and loads and unloads the luggage, the weight of the electric vehicle EV changes. Accordingly, the position of the second coil 31 included in the power receiving device 3 changes in the vertical direction in FIG. 1, the relative position of the second coil 31 with respect to the first coil 21 changes, and a positional shift occurs. obtain.

  For example, assume that the power characteristic is initially the power characteristic indicated by the curve C1. Further, it is assumed that the driving frequency f is the frequency fb1. The load power Pout at this time is the power Pb. Here, it is assumed that a displacement has occurred, the coupling coefficient k has changed, and the power characteristic has changed to the curve shown by the curve C2. In this case, if the driving frequency f remains at the frequency fb1, the load power Pout increases from the power Pb to the power Pa. On the other hand, by increasing the driving frequency f from the frequency fb1 to the frequency fb2 (that is, the frequency control amount Δf = fb2−fb1), the load power Pout can be made to approach the power Pb again.

  As described above, by changing (controlling) the drive frequency f, the magnitude of the load power Pout can be adjusted. By performing such frequency control by the first controller 25, the load power Pout can be made closer to the desired power.

  Here, the slopes of the curves C1 and C2 are different for each drive frequency f. The amount of change in the driving frequency f may correspond to the above-described frequency control amount Δf. Therefore, the slope at each drive frequency f is defined as a load power change rate ΔP / Δf.

  Specifically, the load power change rate ΔP / Δf is a predetermined frequency change amount (for example, frequency control amount Δf = fb1-fa1, Δf = fb1-fc1 or the like) of the drive frequency f from a reference frequency (for example, frequency fb). And a change amount ΔP of the load power Pout supplied to the load L (for example, a change amount ΔP = Pa−Pb, Pc−Pb). The load power change rate ΔP / Δf can be set corresponding to different reference frequencies (for example, frequencies fa1, fb1, fc1, etc.).

  In order to execute the frequency control using the load power change rate ΔP / Δf, in the present embodiment, the load power change rate ΔP / Δf in the contactless power supply system 1 is set.

  For example, the load power change rate ΔP / Δf may be determined and set in real time based on a change in the load power Pout with respect to a change in the drive frequency f during the frequency control. Alternatively, the load power change rate ΔP / Δf is received from another device provided with the power receiving device 3 (for example, an electric vehicle EV to be supplied with power) via communication with the outside of the power transmitting device 2 and set. Is also good. In this case, since the other devices know the characteristics of the power receiving device 3, an appropriate load power change rate ΔP / Δf corresponding to the power receiving device 3 is acquired. Therefore, for example, even when the characteristics and the like of the power receiving device 3 are different for each type of vehicle, non-contact power supply is performed at an appropriate load power change rate ΔP / Δf. When the load power change rate ΔP / Δf is received from outside the power transmission device 2, numerical data indicating the load power change rate ΔP / Δf may be received, or the power characteristics of some predetermined patterns may be received. May be received. If the pattern of the power characteristics is specified, the load power change rate ΔP / Δf can be set according to the specified power characteristics. Alternatively, the load power change rate ΔP / Δf may be set in advance. When the load power change rate ΔP / Δf is set in advance, the load power change rate ΔP / Δf may be set based on experimental data, or the design data of the power transmitting device 2, the power receiving device 3, and the load L may be set. May be set by simulation or the like.

  The load power change rate ΔP / Δf set as described above is described, for example, by a data table stored in a storage unit (not shown) (not shown) included in the first controller 25.

  Next, an example of a method for creating the above data table will be described with reference to FIGS.

  FIG. 4 is a diagram illustrating an example of power characteristics in the wireless power supply system 1. In the graph of FIG. 4, each of the power characteristics when the coupling coefficient k is 0.1, 0.2, 0.3, 0.4, and 0.5 is represented by curves C11, C12, curves C21, C22, and curves. C31 and C32, curves C41 and C42, and curves C51 and C52 are respectively shown by two curves. Curves C11, C21, C31, C41, and C51 show power characteristics when the voltage range of the load power Pout is a relatively high voltage range (for example, 301 V to 400 V or more). Curves C12, C22, C32, C42, and C52 show power characteristics when the power range of the load power Pout is a relatively low voltage range (for example, less than 100 V, 100 V to 200 V, 201 V to 300, and the like). In this example, a method of creating a data table using power characteristics at five different coupling coefficients k will be described. However, a data table may be created using power characteristics at more different coupling coefficients k. .

  First, the graph shown in FIG. 4 is divided into a plurality of areas. For example, the graph of FIG. 4 is divided into a plurality of areas by dividing the graph in FIG. 5 in the range of the load power Pout as shown by the dashed line and in the range of the driving frequency f as shown by the dashed line. I do.

  The data table to be created describes the corresponding load power change rate ΔP / Δf for each of the plurality of divided areas by numerical data. Here, the load power change rate ΔP / Δf is a slope of the power characteristic indicated by a curve such as the curve C11. If the area is set too wide, the value of the load power change rate ΔP / Δf corresponding to the area becomes large. It may not be properly represented. Therefore, the size of the divided area, that is, the driving frequency that determines the area, is determined so that the value of the load power change rate ΔP / Δf corresponding to each area is more appropriately indicated. The range of f and the range of load power Pout are set. Specifically, a portion in the graph where the change in the slope of the curve is relatively large is divided into relatively small areas, and a portion in which the change in the slope of the curve is relatively small is divided into relatively large areas. That is, when different reference frequencies are arranged in ascending or descending order, the interval between adjacent reference frequencies is set to be wider as the amount of change in the load power change rate ΔP / Δf with respect to the drive frequency f is smaller. In other words, the interval between adjacent reference frequencies is set to be narrower as the change amount of the load power change rate ΔP / Δf with respect to the drive frequency f is larger.

  Then, a load power change rate ΔP / Δf corresponding to the plurality of divided areas is obtained as numerical data. The numerical data is calculated, for example, as the magnitude of the steepest slope among the slopes of a curve (a plurality of curves may be included) included in the corresponding area. However, the calculation method of the numerical data is not limited to this. For example, the numerical data may be calculated as the magnitude of the gradient when a curve included in the corresponding area is first-order approximated. When a plurality of curves are included in the same area, a slope value when each curve is linearly approximated may be calculated, and a slope value having the largest magnitude among them may be calculated as numerical data. Alternatively, the average value of the calculated slopes of the respective curves may be calculated as numerical data.

  In the control for actually changing (increasing and decreasing) the driving frequency f, the driving frequency f may be changed in steps. The steps are determined, for example, by the resolution of the clock of the CPU as the first controller 25. The size of one step is not particularly limited, and may be, for example, about several Hz to several tens Hz, or several tens Hz to several hundred H. Therefore, the unit of the load power change rate ΔP / Δf described in the data table may be W / step.

  The data table may be created according to the voltage range of the load power Pout. For example, when the load L is a storage battery, the voltage range varies depending on the configuration of the storage battery, the charge / discharge state of the storage battery, and the like. For example, when the voltage range of the load power Pout is a relatively high voltage range, the corresponding data table is created based on the power characteristics indicated by a plurality of curves including the curves C11, C21, C31, C41, and C51. Good. When the voltage range of the load power Pout is a relatively low voltage range, the corresponding data table may be created based on the power characteristics shown by a plurality of curves including the curves C12, C22, C32, C42, and C52.

  Specifically, FIG. 6 shows an example of a data table when the voltage range of the load power Pout is a relatively high voltage range. This data table is created based on the power characteristics indicated by the curves C11, C21, C31, C41, and C51 in FIG. 5 and other curves not shown in FIG. As shown in FIG. 5, this data table describes the load power change rate ΔP / Δf corresponding to each area defined by the range of the predetermined drive frequency f and the range of the load power Pout by numerical data.

  In the data table shown in FIG. 6, the range of the drive frequency f is separated by a two-dot chain line. The value corresponding to each range of the driving frequency f is a value indicating that the driving frequency f in the range does not exceed the value. For example, the range of the drive frequency f in which the drive frequency f is indicated as “84” in the data table is a range of 83.5 kHz (that is, 84-0.5 kHz) or more and less than 84 kHz. The range of the drive frequency f in which the drive frequency f is indicated as “85” in the data table is a range from 84 kHz to less than 85 kHz.

  In the data table shown in FIG. 6, the range of the load power Pout is separated by a dashed line. The value corresponding to each range of the load power Pout is the lower limit value of the load power Pout in that range. For example, the range of the load power Pout in which the load power Pout is indicated as “1000” in the data table is a range of 1000 W or more and less than 2000 W.

  FIG. 7 shows an example of a data table when the voltage range of the load power Pout is a relatively low voltage range. This data table is created using the power characteristics indicated by the curves C12, C22, C32, C42, C52 in FIG. 5 and other curves not shown in FIG. The data table of FIG. 7 is different from the data table of FIG. 6 in that numerical data is different.

  Thus, a data table describing different numerical data, such as the data table shown in FIG. 6 and the data table shown in FIG. 7, can be created according to the voltage range of the load power Pout. By referring to the data tables shown in FIGS. 6 and 7, the numerical data corresponding to each area, that is, the load power change rate ΔP / Δf in the range of the drive frequency f and the range of the load power Pout can be obtained. As a result, the amount of change in the load power Pout when the drive frequency f is changed can be obtained.

  Specifically, the data table shown in FIG. 7 will be described as an example. Initially, it is assumed that the driving frequency f is 84.5 kHz and the load power Pout is 3300 W. The corresponding area in the data table is defined by a range where the drive frequency f is indicated as “85” and a range where the load power Pout is indicated as “3000”. The load power change rate ΔP / Δf corresponding to this area is “−63”. This load power change rate ΔP / Δf means that when the drive frequency f is increased by one step, the magnitude of the load power Pout changes by −63 W (decreases by 63 W). For example, when the desired power is 3000 W, it is necessary to reduce the load power Pout by 300 W from 3300 W to 3000 W. Therefore, the variation ΔP of the load power Pout is −300 W. Since the frequency control amount Δf of the driving frequency f for obtaining the variation amount ΔP of the load power Pout is Δf = (− 300 / −63), it is calculated as approximately +5 steps.

  That is, in this case, the load power Pout can be made closer to the desired power of 3000 W by increasing the drive frequency f by five steps by frequency control.

  On the other hand, it is initially assumed that the driving frequency f is 83.3 kHz and the load power Pout is 500 W. The area in the data table corresponding to this is an area defined by a range where the driving frequency f is shown as “83.5” and a range where the load power Pout is shown as “500”. The load power change rate ΔP / Δf corresponding to this area is “−61”. For example, when the desired power is 3000 W, it is necessary to increase the load power Pout by 2500 W from 500 W to 3000 W. Therefore, the variation ΔP of the load power Pout is +2500 W. Since the frequency control amount Δf of the drive frequency f for obtaining the fluctuation amount ΔP of the load power Pout is Δf = (2500 / −61), it is calculated as approximately −41 steps.

  That is, in this case, the load power Pout can be made closer to the desired power of 3000 W by reducing the drive frequency f by 41 steps by frequency control.

  Incidentally, the load power change rate ΔP / Δf “−61” referred to here is a value most suitable when the load power Pout is, for example, 500 W or more and less than 700 W. Therefore, when the load power Pout is adjusted so that the load power Pout becomes larger than 700 W, the value of the load power change rate ΔP / Δf “−61” is set as a value indicating the load power change rate ΔP / Δf. Is not always the optimal value. In addition, the fact that the value of the load power Pout that is adjusted at one time is too large is not always appropriate from the viewpoint of control stability and the like.

  Therefore, for example, the upper limit of the number of steps when changing the drive frequency f at a time may be set. For example, if the upper limit of the absolute value of the number of steps is set to 20, even if the drive frequency f is to be increased by 41 steps as described above, the increase width can be suppressed to 20 steps. Then, after increasing the drive frequency f by 20 steps, the frequency control amount Δ may be calculated again based on the corresponding load power change rate ΔP / W, and the frequency control may be executed. By repeating such a control cycle, the load power Pout can be made closer to the desired power.

  Next, an operation of the power transmission device 2 will be described with reference to FIG. FIG. 8 is a flowchart illustrating an example of a process performed in the power transmission device 2. Here, a case where load L is a storage battery and the storage battery is charged by electric power from power transmission device 2 will be described as an example. The process of this flowchart is started, for example, in response to the power transmission device 2 receiving a charging start request from the power reception device 3 side.

  First, the first controller 25 executes a charging start sequence (Step S1). For example, the supply of the AC power Pac2 to the first coil 21 is started at the drive frequency f at which the impedance as viewed from the first converter 22 to the first coil 21 side is inductive (not capacitive). Further, for example, the supply of the AC power Pac2 to the first coil 21 is started so as not to activate a protection function for preventing an excessively large current from flowing through the first coil 21.

  Subsequently, the first controller 25 determines whether or not there is an interruption due to the constant power control (step S2). The constant power control is control for supplying desired power to the load L, and is realized by the power control described above. The interrupt occurs, for example, at a predetermined cycle. When it is determined that there is an interruption by the constant power control (YES in step S2), the first controller 25 determines the power command value and the load power value (the magnitude of the load power Pout supplied to the load L). The power value based on the difference is calculated (step S3). The power command value indicates a magnitude of desired power to be supplied to the load L. The magnitude of the load power Pout supplied to the load L may be notified from the power receiving device 3 to the power transmitting device 2 as described above, or may be estimated in the power transmitting device 2 as described later.

  Subsequently, the first controller 25 determines a candidate value Δf1 of the frequency control amount Δf with reference to the data table (Step S4). Specifically, as described above with reference to FIGS. 4 to 7, the data table is referred to, and the frequency control amount Δf for bringing the load power Pout closer to the desired power is calculated. However, the frequency control amount Δf here is a provisional value, and can be changed in steps S6 and S8 described below. Therefore, what is determined in step S4 is the candidate value Δf1 of the frequency control amount Δf.

  Subsequently, the first controller 25 determines whether or not the frequency (drive frequency f) when changed by the candidate value Δf1 is higher than the upper limit frequency fmax (step S5). The upper limit frequency fmax is an upper limit value of the drive frequency f. The upper limit frequency fmax may be, for example, the upper limit value (for example, 90 kHz) of the drive frequency f that can be used by the non-contact power supply system 1, or the impedance when the first converter 21 looks at the first coil 21 is inductive. May be the upper limit of the driving frequency f. When it is determined that the drive frequency f when the frequency is changed by the candidate value Δf1 is higher than the upper limit frequency fmax (YES in step S5), the first controller 25 controls the frequency control amount Δf so that the frequency becomes the upper limit frequency fmax. Is set (step S6). This makes it possible to prevent the drive frequency f from exceeding the upper limit frequency fmax.

  On the other hand, if it is determined in step S5 that the drive frequency f when changed by the candidate value Δf1 is equal to or lower than the upper limit frequency fmax (NO in step S5), the first controller 25 changes the drive frequency f by the candidate value Δf1. It is determined whether the driving frequency f in this case is lower than the lower limit frequency fmin (step S7). The lower limit frequency fmin is a lower limit value of the drive frequency f. The lower limit frequency fmin may be, for example, the lower limit value (for example, 81.38 kHz) of the drive frequency f that can be used by the non-contact power supply system 1, or the impedance when the first converter 21 views the first coil 21 is The lower limit value of the drive frequency f indicating the inductive property may be used. When it is determined that the driving frequency f when the value is changed by the candidate value Δf1 is smaller than the lower limit frequency fmin (YES in step S7), the first controller 25 controls the frequency control amount Δf so that the frequency becomes the lower limit frequency fmin. Set.

  On the other hand, if it is determined in step S7 that the frequency changed by the candidate value Δf1 is equal to or higher than the lower limit frequency min (NO in step S7), the first controller 25 sets the frequency control amount Δf to the candidate value Δf1. It is set (step S9).

  In any of the above steps S6, S8, and S9, the frequency control amount Δf is determined. Then, after the frequency control amount Δf is determined, the first controller 25 changes the frequency (drive frequency f) by the frequency control amount Δf (step S10).

  When it is determined in the previous step S2 that there is no interruption by the constant power control (NO in step S2), or after the frequency is changed by the frequency control amount Δf in step S10, the first controller 25 stops charging. It is determined whether there is a request (step S11). The charge stop request is notified from the power receiving device 3 to the power transmitting device 2 at a timing when, for example, the SOC of the load L as the storage battery becomes sufficiently high and charging becomes unnecessary. When it is determined that there is no charge stop request (NO in step S11), the first controller 25 returns the process to step S2 again. On the other hand, when it is determined that there is a charge stop request (YES in step S11), first controller 25 executes a charge stop sequence (step S12).

  According to the processing of FIG. 8, the first controller 25 controls the drive frequency f based on the load power change rate ΔP / Δf so that desired power is supplied to the load L (step S2). Is calculated and determined (steps S4, S6, S8, S9), and the drive frequency f is changed (controlled) according to the determined frequency control amount Δf (step S10). According to this flowchart, the power supplied to the load L is adjusted without detecting the positional displacement between the first coil 21 and the second coil 31.

  By the way, in the example of the processing shown in FIG. 8, the drive frequency f may be higher than the upper limit frequency fmax (that is, YES in step S5) and the drive frequency f may be lower than the lower limit frequency fmin (that is, YES in step S7). ), The frequency control amount Δf of the drive frequency f is set without distinguishing between a case where the drive frequency f is increased and a case where the drive frequency f is decreased (steps S3, S4, S9).

  Here, depending on the circuit characteristics of the non-contact power supply system 1, the load power change rate ΔP / Δf becomes considerably large, and there is a possibility that the load power Pout increases sharply only by slightly changing the drive frequency f. When the load power Pout increases rapidly, the power flowing through the power transmitting device 2 and the power receiving device 3 rapidly increases, for example, making it difficult to stabilize power control. Further, there is a possibility that various circuits (such as an inverter circuit and a PFC) included in the first converter 22 and the second converter 32 may be deteriorated. To avoid this, the frequency control amount Δf of the drive frequency f when increasing the load power Pout may be suppressed. On the other hand, if the load power Pout becomes excessively large due to a displacement of the first coil 21 and the second coil 31 or some abnormal situation, the load power Pout must be rapidly reduced.

  Therefore, when increasing the load power Pout, the first controller 25 corrects the frequency control amount Δf so that the frequency control amount Δf becomes smaller than the calculated value, and adjusts the corrected frequency control amount Δf. The frequency control may be performed using (according to).

  This will be specifically described with reference to the flowchart shown in FIG. The flowchart shown in FIG. 9 differs from the flowchart shown in FIG. 8 in that steps S41, S42, and S43 are included between step S4 and steps S5 and S7, and the flow between those steps is different. I do.

  That is, as shown in FIG. 9, when the process of step S4 is completed, the first controller 25 determines whether or not the candidate value Δf1 is a positive value (step S41). When it is determined that the candidate value Δf1 is a positive value (YES in step S41), the first controller 25 corrects the candidate value Δf1 by a coefficient A (step S42). This correction is performed to maintain the magnitude (that is, the absolute value) of the candidate value Δf1 at the magnitude of the candidate value Δf1 determined in the previous step S4 or to make the magnitude larger than the magnitude of the candidate value Δf1. It is. The first controller 25 corrects the candidate value Δf1 with the coefficient A, for example, by multiplying the candidate value Δf1 by the coefficient A. In this case, the coefficient A has a value of 1 or more. After the processing in step S42 is completed, the first controller 25 proceeds to step S5. When the candidate value Δf1 is zero and the coefficient A is 1, the process of step S42 may be skipped because the candidate value Δf1 does not change by the correction using the coefficient A.

  On the other hand, if it is determined in step S41 that the candidate value Δf1 is zero or a negative value (NO in step S41), the first controller 25 corrects the candidate value Δf1 with the coefficient B (step S43). This correction is a correction for setting the magnitude (that is, the absolute value) of the candidate value Δf1 to a value smaller than the magnitude of the candidate value Δf1 determined in the previous step S4. The first controller 25 corrects the candidate value Δf1 with the coefficient B, for example, by multiplying the candidate value Δf1 by the coefficient B. The coefficient B in that case is a value less than one. After the processing of step S43 is completed, the first controller 25 proceeds to step S7.

  The processing itself of step S5 and step S7 is as described above with reference to FIG. However, when the candidate value Δf1 is a positive value (YES in step S41), the driving frequency f does not fall below the lower limit frequency fmin. When the candidate value Δf1 is not a positive value (NO in step S41), the driving frequency f does not exceed the upper limit frequency fmax. Therefore, when the candidate value Δf1 is positive (YES in step S41), after the processing in step S42, the processing in step S5, that is, the drive frequency f when the candidate value Δf1 is changed is larger than the upper limit frequency fmax. Is determined, and the process proceeds to step S6 or step S9 according to the determination result. If the candidate value Δf1 is not a positive value (NO in step S41), after the processing in step S43, the processing in step S7, that is, the drive frequency f when the candidate value Δf1 is changed, becomes the lower limit frequency fmin. It is determined whether the value is smaller than the threshold value, and the process proceeds to step S8 or step S9 according to the determination result. The processing after steps S6, S8, and S9 is as described above with reference to FIG.

  According to the processing of FIG. 9, when increasing the load power Pout, that is, when decreasing the drive frequency f (NO in step S41), the magnitude of the frequency control amount Δf is smaller than the magnitude of the calculated value. (Step S43). Therefore, the power supplied to the load L by the frequency control and the power flowing through the power transmitting device 2 and the power receiving device 3 are also prevented from increasing rapidly. On the other hand, when the load power Pout is decreased, that is, when the drive frequency f is increased (YES in step S41), the magnitude of the frequency control amount Δf is equal to or smaller than the calculated value. It is increased (step S42). Therefore, the load power Pout is rapidly reduced.

  Next, the operation and effect of the first controller 25 will be described. For example, the first controller 25 adopts the driving frequency f as a parameter for controlling the AC power Pac2 supplied to the first coil 21 and changes the driving frequency f to change the load supplied to the load L. The drive frequency f is changed so that the power Pout approaches a desired power (power command value).

  In the above embodiment, the power supplied to the load L approaches the desired power based on the load power change amount (load power change rate ΔP / Δf) with respect to the predetermined frequency change amount of the drive frequency f from the reference frequency. Thus, the driving frequency f is changed (frequency control is executed). Specifically, the first controller 25 determines a difference between the load power Pout supplied to the load L and a desired power (power command value) (a change amount ΔP of the load power Pout) and a load power change rate ΔP / Δf. The driving frequency f is changed based on the above. More specifically, the frequency control amount Δf of the drive frequency f is calculated by dividing the difference (the change amount ΔP of the load power Pout) by the load power change rate ΔP / Δf, and using the calculated frequency control amount Δf. By changing (controlling) the drive frequency f, the load power Pout supplied to the load L can be made closer to the desired power. By performing the frequency control based on the load power change rate ΔP / Δf in this manner, the load power supplied to the load L can be detected without detecting the displacement between the first coil 21 and the second coil 31. Pout can be adjusted.

  In the above embodiment, the storage unit of the first controller 25 stores the load power change rate ΔP / Δf. As described with reference to FIGS. 4 to 7, the data table is created in advance, and the first controller 25 stores the data table. The first controller 25 executes frequency control by referring to the data table. That is, it is not necessary to calculate the load power change rate ΔP / Δf in real time. Therefore, the processing time is shortened, and the load power Pout supplied to the load L can be made close to the desired power. In particular, even if a displacement occurs during power supply and the load power Pout supplied to the load L deviates from desired power, the load power Pout supplied to the load L can be quickly brought close to the desired power. That is, power control with good responsiveness is realized.

  The first controller 25 may acquire the load power change rate ΔP / Δf from outside the power transmission device 2. For example, the load power change rate ΔP / Δf is acquired by receiving the load power change rate ΔP / Δf transmitted from another device (for example, a moving body such as a car) provided with the power receiving device 3. In this case, since the moving object such as the car transmitting the load power change rate ΔP / Δf has grasped the characteristics of the power receiving apparatus 3, the load power change rate ΔP / Δf corresponding to the power receiving apparatus 3 is acquired. Thus, the load power Pout is adjusted based on the appropriate load power change rate ΔP / Δf. Therefore, even when power is supplied to the power receiving apparatuses 3 having different types and characteristics, the load power Pout can be appropriately adjusted.

  Further, the graphs shown in FIGS. 4 and 5 of the above embodiment show a plurality of curves indicating the relationship between the driving frequency f and the load power Pout for each of the plurality of different coupling coefficients k. The data tables shown in FIGS. 6 and 7 are created based on all curves corresponding to a plurality of different coupling coefficients k. Therefore, no matter what value the coupling coefficient k changes due to the positional deviation between the first coil 21 and the second coil 31, the load power change rate ΔP corresponding to the coupling coefficient k (that is, the state of the positional deviation). / Δf will be described by the data table. In this case, by referring to the data tables shown in FIGS. 6 and 7 and based on the load power change rate ΔP / Δf described by the data tables, it is possible to execute frequency control irrespective of the state of displacement. It is. Therefore, the frequency control can be performed such that the power supplied to the load L approaches the desired power without detecting the position shift.

  Further, in the frequency control described above, the frequency control amount Δf of the drive frequency f is calculated as a value that fills the difference between the desired power and the load power Pout. For this reason, by changing the drive frequency f by the frequency control amount Δf, the load power Pout is expected to be substantially the same as or substantially close to the desired power. Therefore, there is a high possibility that the load power Pout can be brought close to the desired power in a short time.

  Here, as described above, in order to grasp the load power Pout supplied to the load L provided on the power receiving device 3 side, the magnitude of the load power Pout is determined from the power receiving device 3 together with the power command value. The power transmission device 2 may be notified. In this case, power control is performed based on the load power Pout directly detected by the second detector 33 of the power receiving device 3. Therefore, for example, the accuracy of power control can be improved as compared with the case where the load power Pout supplied to the load L is estimated based on the AC power Pac2 supplied to the first coil 21.

  Further, as described above with reference to FIGS. 4 to 7, the load power change rate ΔP / Δf is set for each of different reference frequencies. Therefore, the first controller 25 changes (controls) the drive frequency f based on the load power change rate ΔP / Δf using the drive frequency f of the AC power Pac2 supplied to the first coil 21 as a reference frequency. )be able to. Thus, even when the load power change rate ΔP / Δf differs depending on the reference frequency, an appropriate load power change rate ΔP / Δf corresponding to the drive frequency f of the AC power Pac2 supplied to the first coil 21 is obtained. Based power control becomes possible. Therefore, the accuracy of power control can be improved.

  Here, the interval between the different reference frequencies may be set to be wider as the amount of change in the load power change rate ΔP / Δf with respect to the drive frequency f is smaller. For example, when the reference frequencies are set at equal intervals at frequency intervals at which an appropriate resolution for the amount of change in load power change rate ΔP / Δf is obtained with reference to a region where the amount of change in load power change rate ΔP / Δf is large, the change in load power change rate ΔP / Δf In an area where the amount is small, the resolution for the load power change rate ΔP / Δf becomes too fine. In this case, the number of reference frequencies, that is, the number of corresponding load power change rates ΔP / Δf becomes too large, and accordingly, the amount of data to be handled becomes unnecessarily large. On the other hand, when the reference frequencies are set at regular intervals at frequency intervals at which an appropriate resolution for the change amount is obtained with reference to a region where the change amount of the load power change rate ΔP / Δf is small, the change in the load power change rate ΔP / Δf In a region where the amount is large, the resolution with respect to the load power change rate ΔP / Δf becomes coarse. In this case, there is a possibility that the power adjustment accuracy cannot be sufficiently increased. According to the above configuration, the interval between the adjacent reference frequencies is set to be wider as the amount of change in the load power change rate ΔP / Δf is smaller, so that the area in which the amount of change in the load power change rate ΔP / Δf is smaller is set. In, the frequency interval is set so that the resolution for the amount of change in the load power change rate ΔP / Δf does not become too fine, and the data amount is suppressed. Further, in a region where the change amount of the load power change rate ΔP / Δf is large, the frequency interval is set so that the resolution with respect to the change amount of the load power change rate ΔP / Δf does not become too coarse. Therefore, the adjustment accuracy of the load power Pout can be maintained while reducing the amount of data to be handled.

  Further, as described above with reference to FIGS. 4 to 7, the load power change rate ΔP / Δf is set for each different voltage range of the load power Pout supplied to the load L. Therefore, for example, even if the load L is a storage battery or the like and the load power change rate ΔP / Δf varies depending on the voltage range of the load power Pout supplied to the load L, an appropriate value corresponding to the voltage of the load power Pout Power control based on the load power change rate ΔP / Δf becomes possible. Therefore, the accuracy of power control can be improved.

  The first controller 25 determines a frequency based on a change amount ΔP of the load power Pout which is a difference between the load power Pout supplied to the load L and a desired power (power command value) and a load power change rate ΔP / Δf. A candidate value Δf1 for the control amount Δf is calculated. Here, as described above with reference to FIG. 9, when increasing the load power Pout supplied to the load L, the first controller 25 decreases the magnitude of the calculated candidate value Δf1. Thus, the driving frequency f may be changed by the frequency control amount Δf, with the corrected candidate value Δf1 as the frequency control amount Δf. Thereby, for example, it is possible to suppress the load power Pout supplied to the load L and the power flowing through the power transmission device 2 and the like from suddenly increasing and it becomes difficult to perform stable power control.

  Incidentally, the first controller 25 can grasp the load power Pout supplied to the load L without notifying the magnitude of the load power Pout from the power receiving device 3 to the power transmitting device 2 as described above. For example, the first controller 25 may estimate the load power Pout based on the AC power Pac2 supplied from the first converter 22 to the first coil 21. This is because the AC power Pac2 and the load power Pout have a relationship. For example, when almost no power loss occurs in the power transmission by the non-contact power supply system 1, the magnitude of the AC power Pac2 supplied to the first coil 21 is approximately equal because the magnitudes of the AC power Pac2 and the load power Pout are substantially equal. Can be estimated as the load power Pout supplied to the load L. When considering the power loss, the magnitude of the power loss is set to a predetermined value (for example, 5%), and the value obtained by subtracting the magnitude of the power loss from the magnitude of the AC power Pac2 is determined as the load power. It can be estimated as Pout. Since the load power Pout supplied to the load L is estimated based on the AC power Pac2 supplied to the first coil 21 in this manner, for example, it is not necessary to notify the load power Pout from the power receiving device 3 to the power transmitting device 2. can do. In this case, the power transmission device 2 and the power reception device 3, that is, the configuration of the non-contact power supply system 1 is simplified, and the possibility of reducing costs is increased.

  The embodiments of the present invention have been described above, but the present invention is not limited to the above embodiments. For example, in the above embodiment, the case where the frequency control is mainly used as the power control has been described. However, the above-described phase shift control and the control of the DC power Pdc may be used as the power control.

  When the phase shift control is used as the power control, as a parameter for controlling the AC power Pac2 supplied to the first coil 21, the parameter of the switching element included in the inverter circuit described above with reference to FIG. The shift amount of the driving time may be employed. In this case, the power change rate is a change amount of the load power Pout with respect to the change amount of the shift amount of the driving time. Such a data table describing the power change rate can be created using the same method as that of the frequency control.

  When the control of the DC power Pdc is used as the power control, the magnitude of the voltage of the DC power Pdc may be employed as a parameter for controlling the AC power Pac2 supplied to the first coil 21. In this case, the power change rate is a change amount of the load power Pout with respect to a change amount of the voltage of the DC power Pdc. A data table describing such a power change rate can also be created using the same method as in the case of frequency control.

  Further, as the power control, control of the impedance of the wireless power supply system 1 may be employed. When the impedance of the elements constituting the power transmission device 2 of the non-contact power supply system 1 changes, the impedance of the non-contact power supply system 1 changes, and the AC power Pac2 supplied by the first converter 22 also changes. That is, the impedance of the non-contact power supply system 1 may be adopted as a parameter for controlling the AC power Pac2 supplied to the first coil 21. For example, at least one of the first coil 21 and a capacitor or an inductance that can be connected to the first coil 21 is realized by a variable element, and by changing the impedance of the variable element, the impedance of the wireless power transfer system 1 changes. I do. In this case, the power change rate is the change amount of the load power Pout with respect to the change amount of the impedance of the variable element. A data table describing such a power change rate can also be created using the same method as in the case of frequency control.

  Further, in the above-described embodiment, a case has been described in which the power supplied to the load L (load power) approaches the desired power based on the power change rate, but the power change rate may define a change in current. . When the voltage (load voltage) applied to the load L does not change (or the change is extremely small), the load power is proportional to (almost proportional to) the current supplied to the load L (load current). By dividing the desired power by the load voltage, a desired current for realizing the desired power is obtained. In this case, the power change rate is the change amount of the load current with respect to the change amount of the drive frequency f (or the shift amount of the drive time in the phase shift, the magnitude of the voltage of the DC power Pdc, the impedance of the variable element). By bringing the load current closer to the desired current based on the power change rate, the load power can be made closer to the desired power.

DESCRIPTION OF SYMBOLS 1 Non-contact electric power supply system 2 Power transmission device 3 Power receiving device 21 1st coil 22 1st converter 23 1st detector 24 1st communication device 25 1st controller 26 power converter 27 DC / AC converter 31 2nd coil 32nd 2 converter 33 second detector 34 second communicator 35 second controller PS power supply L load

Claims (12)

A power transmission device for supplying power to a power reception device connected to a load,
A first coil for transmitting the power to the second coil of the power receiving device in a non-contact manner;
A converter that receives power, converts it into AC power, and supplies the converted AC power to the first coil;
A controller that changes a parameter for controlling the AC power,
With
The controller, for a predetermined change amount of the parameter from a reference value, based on a power change rate indicating a change amount of the power supplied to the load, the power supplied to the load to the desired power A power transmission device that changes the parameter so as to approach.   The power transmission device according to claim 1, wherein the controller stores the power change rate.   The power transmission device according to claim 1, wherein the controller acquires the power change rate from outside the power transmission device.   The power transmission according to any one of claims 1 to 3, wherein the controller changes the parameter based on a difference between the power supplied to the load and the desired power and the power change rate. apparatus. The parameter is a frequency of the AC power,
The power transmission device according to claim 1, wherein the reference value is a reference frequency determined for a frequency of the AC power. The power change rate is set for each of the different reference frequencies,
The controller is configured such that the power supplied to the load approaches the desired power based on a power change rate having a frequency of the AC power supplied to the first coil as a reference frequency. The power transmission device according to claim 5, wherein the frequency of the AC power is changed.   When the different reference frequencies are arranged in ascending or descending order, an interval between adjacent reference frequencies is set to be wider as the amount of change in the power change rate with respect to the frequency of the AC power is smaller. 7. The power transmission device according to 6. The power change rate is set for each of different voltage ranges of the power supplied to the load,
The controller is configured such that, based on a power change rate corresponding to a voltage range including a voltage of the power supplied to the load, the power supplied to the load approaches the desired power, Change parameters,
The power transmission device according to claim 1.   The controller calculates a control amount of the parameter based on a difference between the power supplied to the load and the desired power and the power change rate, and increases the power supplied to the load. The power transmission according to any one of claims 1 to 8, wherein, in the case, the correction is performed so that the calculated control amount of the parameter is reduced, and the parameter is changed by the control amount of the corrected parameter. apparatus.   10. The method according to claim 9, wherein when the power supplied to the load is reduced, the calculated control amount of the parameter is corrected so as to increase, and the parameter is changed by the control amount of the corrected parameter. The power transmission device according to claim 1. Wherein the controller, the AC power the power supplied to the load is estimated based on, as the power estimated approaches the desired power, changing the parameters of claim 1-10 The power transmission device according to claim 1. A power transmission device according to any one of claims 1 to 11 ,
The power receiving device;
With
The power receiving device is capable of communicating with the power transmitting device,
The power receiving device includes a detector that detects power supplied to the load,
The non-contact power supply system, wherein the controller changes the parameter such that power detected by the detector approaches the desired power.

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