JP2017108632A - Control device, control method and wireless power transmission device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable control for enhancing power transmission efficiency with a simple configuration.SOLUTION: In a control device, a power transmission information acquisition section acquires power transmission information indicating at least one of first electric power, a first voltage and a first current of a first place in a power transmission unit wirelessly transmitting electric power, a power reception information acquisition section acquires power reception information indicating at least one of second electric power, a second voltage and a second current of a second place in a power reception unit receiving the electric power from the power transmission unit, the transmission state acquisition section acquires parameters indicating a state of electric power transmission from the power transmission unit to the power reception unit based on the power transmission information and the power reception information, and the adjustment section selects any one of power transmission adjustment processing for adjusting power transmission electric power of the power transmission unit and impedance adjustment processing for adjusting impedance of the power reception unit according to the parameters and executes the selected processing.SELECTED DRAWING: Figure 1

Description

  Embodiments described herein relate generally to a control device, a control method, and a wireless power transmission device.

  In wireless power transmission, it is known that the power transmission efficiency changes depending on the transmission distance and load impedance. From the viewpoint of effective use of electric power energy, in wireless power transmission, it is desirable to supply electric power supplied to the power transmission side to the power receiving side with as little loss as possible, that is, to increase transmission efficiency.

  A method for controlling transmission efficiency when transmission conditions such as transmission distance change is known. This method includes means for changing the value of any power transmission / reception element, calculates and compares the transmission efficiency before and after changing the value, and controls the value of the power transmission / reception element to increase the transmission efficiency. Therefore, since it is necessary to search for a condition for increasing the transmission efficiency, there is a problem that the processing becomes complicated.

JP 2010-252497 A

  Embodiments of the present invention are intended to enable control that increases power transmission efficiency with a simple configuration.

  A control device as an embodiment of the present invention includes a power transmission information acquisition unit, a power reception information acquisition unit, a transmission state acquisition unit, and an adjustment unit.

  The power transmission information acquisition unit acquires power transmission information representing at least one of a first power, a first voltage, and a first current at a first location in a power transmission unit that wirelessly transmits power.

  The power reception information acquisition unit acquires power reception information representing at least one of a second power, a second voltage, and a second current at a second location in the power reception unit that receives power from the power transmission unit.

  The transmission state acquisition unit acquires a parameter representing a state of power transmission from the power transmission unit to the power reception unit based on the power transmission information and the power reception information.

  The adjustment unit selects and executes one of a power transmission adjustment process for adjusting the transmission power of the power transmission unit and an impedance adjustment process for adjusting the impedance of the power receiving unit, according to the parameter.

The block diagram of the wireless power transmission apparatus which concerns on embodiment of this invention. The figure which shows the example of the connection form of a coil and a capacity | capacitance. The figure for demonstrating the example which estimates transmission efficiency using the voltage concerning a capacity | capacitance. The figure for demonstrating the example which estimates transmission efficiency using the voltage concerning a coil. The figure for demonstrating the example which estimates the transmission efficiency using the electric current which flows into a capacity | capacitance. The figure which shows the partial structure of the wireless power transmission apparatus with which the coil and the capacity | capacitance were connected in parallel based on 1st Embodiment. The figure which shows the operation | movement flow of a control apparatus. The figure which shows the operation | movement flow of a control apparatus further provided with the comparison of a voltage ratio and a 3rd predetermined range, and electric power and a 4th predetermined range. The figure which shows the operation | movement flow in the case of comparing with a received electric power and a 2nd predetermined range before the comparison with a voltage and a 1st predetermined range. The figure which shows the operation | movement flow in the case of changing another adjustment signal, when an adjustment signal reaches an upper limit or a minimum. The figure which shows the operation | movement flow in the case of changing a power transmission adjustment signal according to the determination result of a voltage ratio, and changing a load adjustment signal according to the determination result of received power. The figure which shows the operation | movement flow including the determination using transmitted power. The figure which shows the operation | movement flow which determines whether received electric power is below an upper limit first. The figure which shows the example of the load containing the DC / DC converter with a variable conversion ratio. The figure which shows the example of the load containing the AC / AC converter with a variable conversion ratio. 1 is a configuration diagram of a wireless power transmission apparatus in which a DC / AC converter is disposed on a power transmission side and an AC / DC converter is disposed on a power reception side. FIG. 2 is a block diagram of a calculation unit shown in FIG.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

  FIG. 1 shows a configuration of a wireless power transmission device including the control device according to the present embodiment.

  The wireless power transmission device includes a power transmission unit 21 that transmits power, a power reception unit 31 that receives power, and a control device 11. The control device 11 may be incorporated in the power transmission unit 21 or the power reception unit 31, or may be provided separately from the power transmission unit 21 and the power reception unit 31.

  The power transmission unit 21 includes an AC power source 22 that generates AC power and a power transmission unit connected to the AC power source 22. The power transmission unit includes a coil 1 and a capacitor 1. The coil 1 and the capacitor 1 are connected in series. A power transmission adjustment signal for adjusting the output of the AC power supply is input from the control device 11 to the AC power supply 22.

  The method for adjusting the output of the AC power supply may be any method as long as it can change the output power. For example, the transmission voltage amplitude or current amplitude may be changed to a value corresponding to the transmission adjustment signal. Alternatively, the transmission power may be controlled to be constant at a value indicated by the power transmission adjustment signal. Or you may change the ratio of the time when an alternating current waveform is output according to a power transmission adjustment signal.

  The power receiving unit 31 includes a load 32 and a power receiving unit connected to the load 32. The power receiving unit includes a coil 2 and a capacitor 2. The coil 2 and the capacitor 2 are connected in series. The load 32 may be any device that consumes or stores power. A load adjustment signal for adjusting the impedance of the load 32 is input from the control device 11 to the load 32 as a load adjustment signal for adjusting the impedance of the power receiving unit 31.

  The method of adjusting the impedance by the load adjustment signal may be, for example, a method of changing the power consumed or stored by the load. When the load includes a device whose impedance is variable in addition to a device that consumes or stores electric power, the load impedance may be changed by adjusting the device.

  Information on the power consumed or accumulated by the load 32 is output to the control device 11 as load power information. The power information may be, for example, information indicating the value of power itself, or voltage or current information.

  The coil 1 and the capacitor 1 on the power transmission side and the coil 2 and the capacitor 2 on the power reception side form a power transmission / reception unit 41. In the power transmission / reception unit 41, power transmission is performed between the coils via magnetic coupling. That is, in the coil 1, a magnetic field corresponding to the AC power from the AC power source 22 is generated, and this magnetic field is coupled to the coil 2, whereby the AC power is transmitted to the power receiving side. The transmitted electric power is supplied to the load 32, and electric power is consumed or accumulated in the load 32.

  The power transmission unit 21 is provided with a terminal 1. The terminal 1 is for detecting the voltage at one end of the capacitor 1 opposite to the coil 1, that is, the input voltage to the power transmission / reception unit. Although the voltage is detected here, a configuration for detecting current as described later is also possible.

  The power receiving unit 31 is provided with a terminal 2. The terminal 2 is for detecting the voltage at one end of the capacitor 2 opposite to the coil 2, that is, the output voltage of the power transmission / reception unit. Although the voltage is detected here, a configuration for detecting current as described later is also possible.

  The control device 11 includes a detection unit 1, a detection unit 2, and a calculation unit 12. The detection unit 1 detects a voltage at a predetermined location of the power transmission unit 21, specifically, a voltage at the terminal 1. The detection unit 2 detects a voltage at a predetermined location of the power receiving unit 31, specifically, a voltage at the terminal 2. The calculation unit 12 has a function of estimating the transmission efficiency of power from the power transmission unit 21 to the power reception unit 31 based on the voltage detected by the detection unit 1 and the voltage detected by the detection unit 2. The estimated value of transmission efficiency is one of the parameters representing the transmission state of power from the power transmission unit 21 to the power reception unit 31.

  FIG. 17 shows a functional block diagram of the calculation unit 12. The calculation unit 12 includes a power transmission information acquisition unit 13, a power reception information acquisition unit 14, a transmission state acquisition unit 15, and an adjustment unit 16.

  The power transmission information acquisition unit 13 acquires, from the power transmission unit 21, power transmission information representing at least one of power at a predetermined location, voltage at a predetermined location, and current at a predetermined location. As the voltage at the predetermined location and the current at the predetermined location, the results detected by the detection unit 1 may be used. The transmission power may be calculated from the detection result in the detection unit 1, or the power transmission unit 21 may be provided with a function for notifying the control device 11 of information regarding the power itself at an arbitrary location in the power transmission unit 21. Good.

  The power reception information acquisition unit 14 acquires, from the power reception unit 31, power reception information representing at least one of the received power at a predetermined location, the voltage at the predetermined location, and the current at the predetermined location. As the voltage at the predetermined location and the current at the predetermined location, the results detected by the detection unit 2 may be used. The received power may use load power information received from the load 32 or may be calculated from the detection result of the detection unit 2.

  The transmission state acquisition unit 15 acquires a parameter indicating the state of power transmission from the power transmission unit 21 to the power reception unit 31 based on the information acquired by the power transmission information acquisition unit 13 and the power reception information acquisition unit 14. For example, two parameters, that is, an estimated value of power transmission efficiency from the power transmission unit 21 to the power reception unit 31 and the power reception power of the power reception unit 31 are acquired. A method for estimating the power transmission efficiency will be described later. As the received power, the power acquired by the power reception information acquisition unit 14 may be used as it is. There may be a configuration for acquiring transmitted power instead of received power.

  The impedance adjustment unit 16 selects one of the power transmission adjustment process for adjusting the transmission power of the power transmission unit 21 and the impedance adjustment process for adjusting the impedance of the power reception unit 31 according to the parameter acquired by the transmission state acquisition unit 15 To control power transmission. When adjusting the transmission power, a power transmission adjustment signal in which the amount to be adjusted is set is output. When adjusting the impedance, an impedance adjustment signal in which the amount to be adjusted is set is output.

  Note that the detection units 1 and 2 may be provided outside the control device 11, as an independent device, or inside another arbitrary device. The connection between the detection units 1 and 2 and the calculation unit 12 may be either wired or means using wireless communication. For example, the detection unit 1 and the calculation unit 12 may be connected by wire, and the detection unit 2 and the calculation unit 12 may be connected via wireless communication. Conversely, the detection unit 1 and the calculation unit 12 are wireless communication and the detection unit. 2 and the calculation unit 12 may be connected by wire. Furthermore, both the detection unit 1 and the detection unit 2 may be connected to the calculation unit 12 by wireless communication, or both may be connected to the calculation unit 12 by wire.

  In the configuration shown in FIG. 1, the capacitor 1 is connected to the output side of the AC power supply 22, and the coil 1 is connected to the ground terminal side.However, as shown in FIG. It is good also as the replaced structure. The power receiving side may have the same configuration.

  Furthermore, one or both of the capacitor 1 and the coil 1 may be divided and connected. For example, when the capacitor 1 is divided into two, the capacitors 1a and 1b may be connected to both sides of the coil 1 as shown in FIG.

  Alternatively, when the coil 1 is divided into two, the coils 1a and 1b may be connected to both sides of the capacitor 1 as shown in FIG. In this case, electric power is transmitted to the power receiving side by the two coils 1a and 1b. The number of divisions is not limited to 2, and may be 3 or more. The power receiving side may have the same configuration.

  Hereinafter, an example of an operation in which the calculation unit 12 of the control device 11 estimates the power transmission efficiency from the detection results of the voltages at the terminals 1 and 2 will be described.

ここで、L2 はコイル1、コイル2 のインダクタンス、k はコイル間の結合係数、Q1、Q2 はコイル1、コイル2 のQ 値、RL は負荷の抵抗値（受電ユニットのインピーダンス値）である。ω=2πfであり、fは共振周波数である。 When the resonance frequency of capacitance 1 and coil 1 and the resonance frequency of capacitance 2 and coil 2 are close enough to the frequency of power output from the AC power supply, the transmission efficiency of power transmitted between coils 1 and 2 is It is expressed by a formula.

Here, L2 is the inductance of coil 1 and coil 2, k is the coupling coefficient between the coils, Q1 and Q2 are the Q values of coil 1 and coil 2, and RL is the load resistance (impedance value of the power receiving unit). ω = 2πf, and f is the resonance frequency.

This transmission efficiency depends on the load resistance value, and takes a maximum value when the load resistance satisfies the following equation.

となる。 When the above equation (2) is satisfied and the transmission efficiency takes the maximum value, the voltage at terminal 1 and terminal 2 is

It becomes.

V ₁ represents the voltage amplitude at terminal 1 and V ₂ represents the voltage amplitude at terminal 2. The value representing the voltage amplitude may be any value determined by the AC voltage amplitude, such as an rms (root mean squre) value or a peak value.

となり、電圧比はほぼ、

に等しくなる。 Taking the absolute value of equation (3) above, if k ² Q ₁ Q ₂ >> 1,

The voltage ratio is almost

Is equal to

となる。

はコイル1 とコイル2 の寄生抵抗の比の平方根である。つまり、端子1 と端子2 の電圧比を、コイル1 とコイル2 の寄生抵抗比に応じて決まる所定の値と比較することで、現在接続されている負荷32の抵抗が、伝送効率が最適となる負荷抵抗値にどの程度近いかを判定できる。言い換えれば、端子1 と端子2 の電圧を検出することで、電力伝送効率を推定することが可能となる。関連技術では伝送効率の計算のために、送電電力と受電電力を計算する必要があったが、本実施の形態ではその必要はなく、簡易に伝送効率を推定できる。 Here, if the parasitic resistance values of L ₁ and L ₂ are R ₁ and R ₂ , Equation (4) is

It becomes.

Is the square root of the ratio of the parasitic resistances of coil 1 and coil 2. In other words, by comparing the voltage ratio between terminal 1 and terminal 2 with a predetermined value determined according to the parasitic resistance ratio between coil 1 and coil 2, the resistance of the load 32 currently connected can be optimized for transmission efficiency. It can be determined how close the load resistance value is. In other words, it is possible to estimate the power transmission efficiency by detecting the voltages at the terminals 1 and 2. In the related technology, it is necessary to calculate the transmission power and the reception power in order to calculate the transmission efficiency. However, this embodiment does not need this, and the transmission efficiency can be estimated easily.

If the parasitic resistance components of capacitors 1 and 2 are insignificant relative to the parasitic resistance components of coils 1 and 2, R ₁ is the capacitance 1 and R ₂ is the parasitic capacitance 2 It may be a value including resistance.

  As a specific method for estimating transmission efficiency performed by the calculation unit 12 in the control device 11, various forms are possible.

For example, the ratio (or difference) between V ₁ and V ₂ may be calculated, and the calculated voltage ratio (or difference) itself may be used as an index representing transmission efficiency.

との比率（または差）を計算することで、電圧比がどの程度、

に近いか（すなわち伝送効率が最適となる負荷抵抗値に近いか）が分かり、これを伝送効率としてもよい。この場合、比率が1に近いほど（または差が0に近いほど）、最適な伝送効率に近いということになる。 Also, the calculated voltage ratio and

By calculating the ratio (or difference) between and the voltage ratio,

(That is, whether the transmission efficiency is close to the optimum load resistance value), and this may be used as the transmission efficiency. In this case, the closer the ratio is to 1 (or the closer the difference is to 0), the closer to the optimal transmission efficiency.

Further, the range that can be taken by the ratio (or difference) between V ₁ and V ₂ is divided into a plurality of ranges, and a label indicating the good transmission efficiency is assigned to the divided range. The range to which the ratio (or difference) between V ₁ and V ₂ calculated by the calculation unit 12 belongs may be specified, and a label attached to the specified range may be used as the transmission efficiency.

との比率（または差）が取りうる範囲を複数に分割し、分割した範囲に伝送効率の良さを表すラベルを付与する。演算部12で計算した、電圧比と

との比率（または差）が属する範囲を特定し、特定した範囲に付与されているラベルを伝送効率としてもよい。 Similarly, the above voltage ratio and

The range that can be taken by the ratio (or difference) is divided into a plurality of ranges, and a label indicating the good transmission efficiency is assigned to the divided range. The voltage ratio calculated by the calculation unit 12 and

A range to which the ratio (or difference) belongs to is specified, and a label attached to the specified range may be set as the transmission efficiency.

を基準として用いて伝送効率を推定する例を示したが、実際には、R₁、R₂、L₁、L₂などのパラメータは、様々な条件で変動しうる。例えば、抵抗値の特性が温度に対して依存性を持ちうる。また、コイルに磁性体材料を用いる場合、磁性体材料が温度依存性を持ちうる。さらに、流れる電流の大きさや印加される電圧の大きさに対してコイルや容量の特性が変化することが考えられる。 In the above example,

An example is shown in which transmission efficiency is estimated using as a reference, but in reality, parameters such as R ₁ , R ₂ , L ₁ , and L ₂ can vary under various conditions. For example, the characteristic of the resistance value can be dependent on temperature. In addition, when a magnetic material is used for the coil, the magnetic material can have temperature dependence. Further, it is conceivable that the characteristics of the coil and the capacitance change with the magnitude of the flowing current and the magnitude of the applied voltage.

In order to suppress these influences, the values of R ₁ and R ₂ may be measured under a plurality of conditions, and based on the results, the reference value for estimating the transmission efficiency may be determined.

Alternatively, the relationship between the transmission efficiency and the ratio (or difference) between V ₁ and V ₂ may be measured under a plurality of conditions to determine a reference value. As a determination method, for example, a method of selecting a ratio (or difference) between V ₁ and V ₂ that maximizes the transmission efficiency under the condition that the transmission efficiency is most reduced, or an average under a plurality of conditions may be used. The ratio (or difference) between V ₁ and V ₂ may be selected as a reference so that the transmission efficiency is maximized.

  In addition, variations and aging may occur during the manufacture of the coil. A reference value may be determined in consideration of these variations. For example, the value may be determined as a reference so that the transmission efficiency becomes high on average in the range of variation.

  In the configuration example shown in FIG. 1, the transmission efficiency is estimated using the voltages of the terminals 1 and 2, but as shown in FIG. 3, the transmission efficiency is estimated using the voltage applied to the capacities 1 and 2. Also good. In this case, the detection unit 1 and the detection unit 2 of the control device 11 detect the voltage applied to the capacitors 1 and 2. The calculation unit 12 estimates the transmission efficiency using the voltage applied to the capacitors 1 and 2. In FIG. 3, the control device is not shown.

V₁、V₂ はそれぞれ容量1、容量2にかかる電圧である。絶対値をとり、近似すると、

となり、V₁とV₂の比は、インダクタンス比と寄生抵抗の比により決まる値となる。つまり、容量1，2の電圧比を、インダクタンス比と寄生抵抗の比に応じて決まる所定の値と比較することで、現在接続されている負荷32の抵抗が、伝送効率が最適となる負荷抵抗値にどの程度近いかを判定できる。具体的な推定方法は、上述した端子1,2の電圧を用いた場合と同様にして行えばよい。 In this example, the transmission efficiency can be expressed as:

V ₁ and V ₂ are voltages applied to the capacitor 1 and the capacitor 2, respectively. Taking an absolute value and approximating it,

Thus, the ratio of V ₁ and V ₂ is a value determined by the ratio of the inductance ratio and the parasitic resistance. In other words, by comparing the voltage ratio of the capacitors 1 and 2 with a predetermined value determined according to the ratio of the inductance ratio and the parasitic resistance, the resistance of the currently connected load 32 is the load resistance that optimizes the transmission efficiency. You can determine how close to the value. A specific estimation method may be performed in the same manner as in the case where the voltages at the terminals 1 and 2 are used.

  In the configuration example shown in FIG. 3, the transmission efficiency is estimated using the voltages of the capacitors 1 and 2, but as shown in FIG. 4, the transmission efficiency is estimated using the voltages applied to the coils 1 and 2. good. In this case, the detection unit 1 and the detection unit 2 of the control device 11 detect the voltage applied to the coils 1 and 2. In FIG. 4, illustration of the control device is omitted. The calculation unit 12 estimates the transmission efficiency using the voltages of the coils 1 and 2.

The transmission efficiency in this example can be expressed as the following equation.

となる。つまり、この場合も、V₁,V₂の比は、インダクタンス比と寄生抵抗の比により決まる値となる。つまり、コイル1，2の電圧比を、インダクタンス比と寄生抵抗の比に応じて決まる所定の値と比較することで、現在接続されている負荷32の抵抗が、伝送効率が最適となる負荷抵抗にどの程度近いかを判定できる。具体的な推定方法は、上述した端子1,2の電圧を用いた場合と同様にして行えばよい。 V ₁ and V ₂ are voltages applied to the coils 1 and 2, respectively. Taking an absolute value and approximating it,

It becomes. That is, also in this case, the ratio of V ₁ and V ₂ is a value determined by the ratio of the inductance ratio and the parasitic resistance. In other words, by comparing the voltage ratio of the coils 1 and 2 with a predetermined value determined according to the ratio of the inductance ratio and the parasitic resistance, the resistance of the load 32 currently connected becomes the load resistance at which the transmission efficiency is optimum. How close it is to A specific estimation method may be performed in the same manner as in the case where the voltages at the terminals 1 and 2 are used.

  In the example shown in FIGS. 3 and 4, the transmission efficiency is estimated using the voltage. However, it is also possible to estimate the transmission efficiency using the current flowing through the capacitors 1 and 2 as shown in FIG. In this case, the detection unit 1 of the control device 11 detects the current flowing through the capacitor 1, and the detection unit 2 detects the current flowing through the capacitor 2. The calculation unit 12 estimates the transmission efficiency using the value of the current flowing through the capacitors 1 and 2 detected by the detection units 1 and 2. In FIG. 5, the control device is not shown.

I₁、I₂ はそれぞれ容量1、容量2に流れる電流である。近似すると

となり、電流比もR₁、R₂ の比により決まる値となる。つまり、容量1，2を流れる電流の比を、R₁、R₂ の比に応じて決まる所定の値と比較することで、現在接続されている負荷32の抵抗が、伝送効率が最適となる負荷抵抗にどの程度近いかを判定できる。具体的な推定方法は、上述した端子1,2の電圧を用いた場合と同様にして行えばよい。 In this example, the transmission efficiency can be expressed as:

I ₁ and I ₂ are currents flowing through the capacitors 1 and 2, respectively. Approximate

Thus, the current ratio is also determined by the ratio of R ₁ and R ₂ . In other words, by comparing the ratio of the current flowing through the capacitors 1 and 2 with a predetermined value that is determined according to the ratio of R ₁ and R ₂ , the resistance of the load 32 that is currently connected has the optimum transmission efficiency. How close to the load resistance can be determined. A specific estimation method may be performed in the same manner as in the case where the voltages at the terminals 1 and 2 are used.

  In the example shown in FIGS. 3 to 5, the case where the capacitor 1 and the capacitor 2 are connected in series to the coil 1 and the coil 2 is shown. However, as shown in FIG. Capacitor 1 and capacitor 2 may be connected in parallel. In FIG. 6, the control device is not shown.

  At this time, when the resonance frequency of the LC resonance circuit of the capacitor 2 and the coil 2 is sufficiently close to the frequency of the power output from the AC power supply 22, the load resistor 32 having the optimum resistance value is connected. The relationship between the voltage at terminal 1 and terminal 2 is expressed by the following equation (12).

In the configuration of FIG. 6, the value of the capacity 2 at which the transmission efficiency is optimal is the value of the power output from the AC power supply 22 by the LC resonant circuit of the capacity 2 and the coil 2 when k ² << 1 holds. It almost matches the value of capacitance 2 when resonating at frequency. For this reason, only an equation in the case where the LC resonance circuit of the capacitor 2 and the coil 2 resonates at the frequency of the power output from the AC power supply 22 is shown.

Here, V ₁ and V ₂ are the voltages at terminals 1 and 2, respectively. When k ² << 1 holds for the coupling coefficient k, and Q ₁ and Q ₂ have the same magnitude, the absolute values of both sides can be approximated as follows.

That is, the relationship between V ₁ and V ₂ can be approximated using the inductance ratio and the parasitic resistance ratio. In other words, by comparing the voltage ratio between terminal 1 and terminal 2 with a predetermined value determined according to the ratio of inductance and the ratio of parasitic resistance, the resistance of the load 32 currently connected is optimized for transmission efficiency. How close to the load resistance can be determined. A specific estimation method may be performed in the same manner as in the case where the voltages at the terminals 1 and 2 are used.

  In the configuration of FIG. 6, it is also possible to estimate the transmission efficiency using the currents flowing through the coils 1 and 2.

となる。I₁、I₂ はそれぞれコイル1、コイル2 を流れる電流である。これまでと同様に、近似すると次式のようになる。

At this time, the current flowing through the coil when the load resistance value at which the transmission efficiency is maximum is

It becomes. I ₁ and I ₂ are currents flowing through the coils 1 and 2, respectively. As before, the following formula is approximated.

This current ratio can also be approximated by a relational expression based on the ratio of the parasitic resistances R ₁ and R ₂ . In other words, by comparing the current flowing through coil 1 and coil 2 with a predetermined value that depends on the ratio of parasitic resistances R ₁ and R ₂ , the resistance of load 32 currently connected is optimal for transmission efficiency. It is possible to determine how close the load resistance is. A specific estimation method may be performed in the same manner as the method described above.

Similarly, in the configuration shown in FIG. 6, the relationship between the currents flowing through the capacitors 1 and 2 can be approximated by a relational expression based on the ratio of R ₁ and R ₂ . The detailed description is obvious from the above description, and will be omitted.

  As a configuration different from FIGS. 1 and 6, a capacitor may be arranged in series only in one of the coil 1 and the coil 2 and a capacitor may be arranged in parallel in the other. In any case, similarly, when a load having a resistance value that maximizes transmission efficiency is connected, the relationship between the voltage or current on the power transmission side and the power reception side is the ratio of the inductance value and the parasitic resistance value. It can be approximated by the relational expression used.

  Although the formulas show theoretical formulas under ideal conditions, the ratios of parasitic resistance values and inductance values may vary depending on temperature, current amount, etc. in the configurations of FIGS. 3 to 6 as described above. There is also the possibility of variations. Therefore, in consideration of these, the reference value in the configurations of FIGS. 3 to 6 may be determined.

  Based on the description so far, based on the voltage or current detected by the detection units 1 and 2, the calculation unit 12 can estimate how close the transmission efficiency is to the maximum power efficiency. showed that.

  The method shown here is an example of a power efficiency estimation method, and the efficiency estimation method is not limited to this method. For example, when the power transmission information acquisition unit 13 in FIG. 17 acquires information indicating power at any location in the power transmission unit, and the power reception information acquisition unit 14 acquires power at any location in the power reception unit, these The power efficiency may be derived from the ratio. In this case, how close the power efficiency is to the maximum condition may be determined by a mathematical formula. Alternatively, the maximum efficiency may be stored in advance and determined by comparison with the stored value. When the coupling state of the coil changes greatly, a parameter indicating the coupling state of the coil may be acquired separately and the determination may be made by using a mathematical formula using this parameter. Further, the relationship between the coil coupling state and the efficiency may be stored in advance as a table and judged by comparison with the table.

  Next, a method for calculating values of the power transmission adjustment signal and the load adjustment signal in the calculation unit 12 will be described.

  In the configuration shown in FIG. 1, the calculation unit 12 of the control device 11 sets a power transmission adjustment signal and a load adjustment signal, the power transmission adjustment signal is output to the AC power source 22, and the load adjustment signal is output to the load 32. Is possible. Thereby, both voltage ratio and electric power can be adjusted.

  As a method for adjusting the power by the load adjustment signal, for example, the input of the device that consumes or stores the power of the load is adjusted so as to have a constant power, a constant current, a constant voltage, and the like. Further, power, voltage, and current at another arbitrary point in the power receiving unit 31 may be adjusted. Alternatively, the power supplied from the power transmission unit 21 may be adjusted to be constant power, constant current, and constant voltage.

  However, if the two adjustment signals, the power transmission adjustment signal and the load adjustment signal, can be adjusted at the same time or asynchronously, respectively, it is unclear which adjustment signal caused the change in power or voltage ratio. There is a possibility that proper control cannot be performed. Therefore, in the present embodiment, when the control device 11 adjusts the adjustment signal, only one of the power transmission adjustment signal and the load adjustment signal is selected and changed. That is, only one of the impedance adjustment process for adjusting the impedance of the power receiving unit and the power transmission adjustment process for adjusting the transmission power of the power transmission unit is selected and executed. Hereinafter, this operation will be described in detail.

  FIG. 7 shows an example of a flowchart when the control device 11 changes the power transmission adjustment signal and the load adjustment signal.

  In FIG. 7, the control device 11 first determines whether or not the voltage ratio is within a first predetermined range (step S11). In other words, it is determined whether the voltage ratio exceeds the upper limit (threshold value) and the lower limit (threshold value) of the first predetermined range. Note that exceeding exceeds both the upper limit and the lower limit.

If the voltage ratio is not within the first predetermined range, the load adjustment signal is changed so that the voltage ratio is corrected in a direction approaching the first predetermined range (step S12). That is, the load adjustment signal is changed so as to be corrected in a direction approaching the upper limit when exceeding the upper limit of the first predetermined range, and in a direction approaching the lower limit when exceeding the lower limit. For example, the larger the voltage ratio V ₁ / V ₂ than the upper limit of the first predetermined range, it may be larger load resistance, when V ₁ / V ₂ is less than the lower limit of the first predetermined range Therefore, the load resistance value may be reduced. This is a typical case of the configuration shown in FIG. 1, and the increase / decrease relationship when changing the load resistance value is reversed depending on the coil / capacitor connection configuration, element value selection, and load conditions. sell.

  If the voltage ratio is within the first predetermined range, it is determined whether the received power is within the second predetermined range (step S13). In other words, it is determined whether the received power exceeds the upper limit (threshold value) and the lower limit (threshold value) of the second predetermined range. The value of the received power may be the value of the load power information input from the load 32, or may be acquired from the voltage and current detected at a predetermined location of the power receiving unit 32.

  If the received power is not within the second predetermined range, the power transmission adjustment signal is adjusted so that the received power is corrected in a direction approaching the second predetermined range. That is, the power transmission adjustment signal is changed so as to be corrected in a direction approaching the upper limit when exceeding the upper limit of the second predetermined range, and in a direction approaching the lower limit when exceeding the lower limit. For example, the power transmission adjustment signal is changed so that the received power is increased if the received power is smaller than the lower limit of the second predetermined range, and the received power is decreased if the received power is larger than the upper limit of the second predetermined range. (Step S14).

  For example, the amplitude of the AC voltage may be changed by a power transmission adjustment signal so as to increase or decrease the power transmitted from the power transmission unit, or the AC voltage waveform may be adjusted to increase or decrease the amplitude equivalent to the transmitted power. It may be changed by a signal. Or you may adjust the ratio of the time when an alternating voltage signal is output with a power transmission adjustment signal.

  If the voltage ratio is within the first predetermined range and the received power is within the second predetermined range, the process ends without doing anything.

  The first and second predetermined ranges (upper limit threshold and lower limit threshold) are not fixed and may be dynamically changed. In this case, the value of each range is notified to the calculation unit 12 from the external management system or the load 32, and the calculation unit 12 may use the notified value as the first and second predetermined ranges.

  Here, an example of load impedance control using a load adjustment signal will be described.

  When the power to be supplied to the load is variable, the power consumed or accumulated by the load may be changed by a load adjustment signal.

  Alternatively, as shown in FIG. 14, when the AC-DC converter 101 and the DC-DC converter 102 are arranged in the front stage of the power consumption / storage device 103 as the load configuration, the DC-DC converter 102 The voltage conversion ratio may be changed by a load adjustment signal.

  Alternatively, as shown in FIG. 15, when the variable AC-AC converter 104 and the AC-DC converter 105 are arranged in the front stage of the power consumption / storage device 103 as the load configuration, the AC-AC converter The conversion ratio 104 may be changed by a load adjustment signal.

  The control of these loads is merely an example, and the present embodiment is not limited to these.

  FIG. 8 shows an operation flow when an additional operation is performed after the operation shown in FIG.

  Steps S11 to S14 are the same as in FIG.

  If it is determined in step S13 that the received power is within the second predetermined range, then the voltage ratio is compared with a third predetermined range that is narrower than the first predetermined range (step S15), If it is not within the predetermined range, the load adjustment signal is changed so that the voltage ratio is corrected in a direction approaching the third predetermined range (step S16). The relationship between the first and third predetermined ranges is that the third predetermined range is included in the first predetermined range, and the center values of the first and third predetermined ranges are the same. It may be.

  If the voltage ratio is within the third predetermined range, the received power is then compared with a fourth predetermined range that is narrower than the second predetermined range (step S17), and within the fourth predetermined range If not, the power transmission adjustment signal is changed so that the received power is corrected in a direction approaching the fourth predetermined range (step S18). The relationship between the second and fourth predetermined ranges is that the fourth predetermined range is included in the second predetermined range, and the center values of the second and fourth predetermined ranges are the same. It may be.

  The method of changing the load adjustment signal in step S12 and step S16 may be the same or different. For example, the width for changing the load adjustment signal in the change in step S16 may be smaller than the change in step S12. In this case, a more accurate adjustment function is provided in step S16. The same applies to the power transmission adjustment signal in step S14 and step S18.

  Here, in the operation shown in FIG. 7 and FIG. 8, the change of the adjustment signal (load adjustment signal, power transmission adjustment signal) may be increased or decreased within a certain range, and a predetermined range (first to fourth predetermined ranges) Depending on the degree of deviation from (), the change width may be changed and increased or decreased. For example, when the voltage ratio or the received power deviates from a predetermined range by a certain amount or more, the speed of the control operation is improved by increasing the amount to be changed at a time. Alternatively, the value of the amount to be changed is stored in the form of a mathematical formula or a table in accordance with the degree of deviation from the predetermined range, and the degree of deviation from the predetermined range is changed from the mathematical expression or table. The amount may be determined.

  The operations of the flows shown in FIGS. 7 and 8 may be performed at regular time intervals. For example, after the operation of the flow shown in FIGS. 7 and 8 is completed, the next operation may be started after waiting for a longer time than the response time of the entire system. Alternatively, the voltage, current, power, and the like at an arbitrary point may be monitored, and the operation may be performed when the value after the previous adjustment has changed by a certain amount or when the value has changed by a certain speed or more.

  In the operation shown in FIG. 7, the voltage ratio is first compared with the first predetermined range, and the received power is compared with the second predetermined range when the voltage ratio is within the first predetermined range. Thereby, the voltage ratio is adjusted with priority over the received power. Therefore, this operation is suitable when transmission efficiency is more important than received power.

  On the other hand, as shown in FIG. 9, the received power is first compared with the second predetermined range, and when the received power is not within the second predetermined range, the voltage ratio is the first predetermined range. You may determine whether it is in the range. In the case of this operation, the received power is preferentially adjusted so as to fall within the second predetermined range.

Here, in the configuration shown in FIG. 1, the power supplied to the load is expressed by the following equation.

  As can be seen from this equation, the power supplied to the load varies depending on the impedance of the load. In other words, the received power and the transmitted power can be adjusted by the load adjustment signal. Similarly, when the connection configuration of the coil and the capacitor in the power transmission / reception unit is different from that in FIG. 1, it can be expressed by an expression that the power changes depending on the load.

  In addition, when the impedance of the load changes according to the power, such as when charging a secondary battery, the load impedance can also be changed by changing the power transmission adjustment signal and changing the power supplied to the load. it can.

  From these things, as shown in the operation flow of FIG. 10, when the voltage ratio is within the first predetermined range and the received power is not within the second predetermined range (YES in step S21, S22 NO), when the power transmission adjustment signal reaches the upper limit or lower limit of the settable range (YES in step S23), the received power may be adjusted by changing the load adjustment signal (step S25). However, if the load adjustment signal has also reached the upper limit or the lower limit, the process is terminated without doing anything (YES in step S24). If the power transmission adjustment signal does not reach the upper limit or lower limit of the settable range, the power transmission adjustment signal may be changed as before (NO in step S23, S26).

  Further, when the load has the property that the impedance changes according to the electric power, when it is determined that the voltage ratio is not within the first predetermined range and the load adjustment signal reaches the upper limit / lower limit (step S21). NO, YES of S27), the power supplied to the load may be changed (that is, the impedance of the load is changed) by changing the power transmission adjustment signal (step S29). However, if the power transmission adjustment signal has also reached the upper limit or the lower limit, the process is terminated without doing anything (YES in step S28). When the load adjustment signal does not reach the upper limit or lower limit of the settable range, the load adjustment signal may be changed as before (NO in step S27, S30).

  In the operation flow shown in FIG. 7, the load adjustment signal is changed when the voltage ratio is outside the first predetermined range, and the transmission adjustment signal is changed when the received power is outside the second predetermined range. . On the other hand, as in the operation flow shown in FIG. 11, when the voltage ratio is outside the first predetermined range (NO in step S11), the power transmission adjustment signal is changed (step S14), and the received power is the second If it is outside the predetermined range (NO in step S13), the load adjustment signal may be changed (step S12).

  In the operation flow shown in FIG. 7, the received power information is used to determine whether or not the transmission adjustment signal is changed. However, the transmitted power information may be used instead of the received power information. The operation flow in this case is shown in FIG. When it is determined that the voltage ratio is not within the first predetermined range (step S11), the transmitted power is compared with the fifth predetermined range (step S31), and the transmitted power is outside the fifth predetermined range. For example, the power transmission adjustment signal is changed so that the transmitted power is corrected in a direction approaching the fifth predetermined range (step S14). By repeatedly performing the operation shown in FIG. 12, the transmitted power is adjusted within the fifth predetermined range. The information on the transmitted power may be acquired by the control device 11 from the AC power supply 22, or the control device 11 may acquire by calculation from the detection result of the voltage and current at a predetermined location in the power transmission unit. The first and fifth predetermined ranges are not fixed and may be dynamically changed. In this case, the settable range is notified from the external management system or the load 32 to the calculation unit 12, and the calculation unit 12 may use the notified value as the first and fifth predetermined ranges.

  Note that the same modification as the example shown in FIG. 11 can be applied to the operation of FIG. That is. The load adjustment signal may be changed when the transmitted power is outside the fifth predetermined range, and the power transmission adjustment signal may be changed when the voltage ratio is outside the first predetermined range.

  FIG. 13 shows an operation flow in the case of adding an operation for determining whether the received power does not exceed the upper limit value before the operation shown in FIG. 7 is started.

  It is determined whether the received power exceeds the upper limit (step S32), and if it exceeds the upper limit, the power transmission adjustment signal is changed (step S33). The method described so far may be used as the changing method. By repeating the operation of this flow, the received power is set to the upper limit value or less. When the received power is equal to or lower than the upper limit value (YES in step S32), the same operation as shown in FIG. 7 is performed (steps S11 to S14).

  In this way, before the transmission efficiency is prioritized and adjusted (steps S11 and S12), it is determined whether or not the received power exceeds the upper limit value by determining whether or not the received power exceeds the upper limit value. Can be prevented. As a result, it is possible to reduce risks such as overpower and overcurrent that lead to the destruction or stop of the device.

  Up to this point, the operation of the control device with the configuration shown in FIG. 1 has been shown. Similarly, when the configurations shown in FIGS. 2 to 5 are used, the voltages or currents detected from the power transmission unit and the power reception unit, respectively. Based on the above, transmission power control and load impedance control may be performed.

  In the present embodiment, the example in which the voltage ratio matches or approaches a predetermined range by adjusting the impedance value of the load 32 has been shown. However, as another method, this can be achieved by adjusting the inductance or the coupling coefficient. It is also possible to do this.

  For example, as an inductance change, it is possible to change the arrangement (including addition / removal of the magnetic material) of the magnetic material in the coil or around the coil. The coil is a coil included in one or both of the power transmission unit and the power reception unit.

  Further, as a change of the coupling coefficient, it is possible to change the relative position between the coils of the power transmission unit and the power reception unit. Alternatively, similarly to the change of the inductance, it is possible to change the arrangement of the magnetic body in the coil or around the coil (including addition / removal of the magnetic body).

  As described above, according to the present embodiment, the impedance can be adjusted to a value close to the load impedance value at which the transmission efficiency is optimum. Alternatively, the inductance or the coupling coefficient can be adjusted so that the impedance value of the connected load is close to the impedance value at which the transmission efficiency is optimal.

  FIG. 16 shows a configuration example in which a DC power supply 71 and a DC-AC converter 51 are arranged on the power transmission side, and an AC-DC converter 61 is arranged on the power reception side. The difference from the configuration in FIG. 1 is that the AC power source 22 on the power transmission side in FIG. 1 is replaced with a DC power source 71, and a DC-AC converter 51 is added. An AC-DC converter 61 is added on the power receiving side. Elements having the same names as those in FIG. 1 are denoted by the same reference numerals, and redundant description is omitted.

  In the case of the configuration shown in FIG. 16, the input voltage or current of the DC-AC converter 51 and the output voltage or current of the AC-DC converter 61 are used as the voltage or current used for transmission efficiency estimation. it can.

  The detection unit 1 detects the input voltage or current of the DC-AC conversion unit 51, and the detection unit 2 detects the output voltage or current of the AC-DC conversion unit 61.

  The calculation unit 12 estimates the transmission efficiency using the voltage or current detected by the detection unit 1 and the voltage or current detected by the detection unit 2 in the same manner as described with reference to FIG. 1 or FIG. . The DC-AC converter 51 can be constituted by, for example, an inverter, and the AC-DC converter 61 can be constituted by, for example, a rectifier.

  The configuration shown in FIG. 6 allows easier implementation by detecting a DC voltage or a DC current.

  Note that the present invention is not limited to the above-described embodiment as it is, and can be embodied by modifying the constituent elements without departing from the scope of the invention in the implementation stage. In addition, various inventions can be formed by appropriately combining a plurality of components disclosed in the embodiment. For example, some components may be deleted from all the components shown in the embodiment. Furthermore, constituent elements over different embodiments may be appropriately combined.

Claims (15)

A power transmission information acquisition unit that acquires power transmission information representing at least one of the first power, the first voltage, and the first current of the first location in the power transmission unit that generates a magnetic field by the coil;
Power reception that acquires power reception information representing at least one of the second power, the second voltage, and the second current of the second location obtained by coupling the magnetic field with the coil of the power reception unit by the magnetic field generated in the power transmission unit An information acquisition unit;
Based on the power transmission information and the power reception information, a transmission state acquisition unit that acquires a parameter representing a coupling state of the coil of the power transmission unit and the power reception unit;
According to the parameter, an adjustment unit that selects and executes one of a power transmission adjustment process for adjusting the first power of the power transmission unit and an impedance adjustment process for adjusting the impedance of the power reception unit;
A control device comprising: The transmission state acquisition unit acquires a plurality of parameters including a first parameter and a second parameter,
The adjustment unit selects one of the power transmission adjustment process and the impedance adjustment process according to at least the value of the first parameter and the value of the second parameter.
The control device according to claim 1. The adjustment unit performs one of the power transmission adjustment process and the impedance adjustment process according to a comparison between the first parameter value and the first threshold value, and a comparison between the second parameter value and the second threshold value. select,
The control device according to claim 2.   When the value of the first parameter is higher than a third threshold value or lower than a fourth threshold value, the adjustment unit is changed so that the value of the first parameter approaches the third threshold value or the fourth threshold value. , Executing one of the power transmission adjustment process and the impedance adjustment process, the value of the first parameter does not exceed the third threshold and does not fall below the fourth threshold, and the value of the second parameter is The second process according to claim 2, wherein the second process is executed so that the value of the second parameter is changed in a direction approaching the fifth threshold or the sixth threshold when the fifth threshold is exceeded or the sixth threshold is exceeded. Control device. One of the first and second parameters represents an estimated value of power efficiency of the power transmission unit and the power reception unit,
5. The control device according to claim 4, wherein the other of the first and second parameters represents one of a second power of the power receiving unit and a first power of the power transmission unit.   The estimated value of the power efficiency is a ratio between the first power and the second power, a ratio between the first voltage and the second voltage, and the first current and the second current between the power transmission unit and the power reception unit. 6. The control device according to claim 5, wherein the control device is a value based on any one of the ratios. The adjustment unit determines whether the value of the parameter exceeds a predetermined threshold, whether the power transmission adjustment reaches the upper or lower limit of the adjustable range, and whether the impedance adjustment can be adjusted to the upper or lower limit of the adjustable range. Selecting one of the power transmission adjustment process and the impedance adjustment process according to at least one of whether or not it has reached,
The control device according to claim 1.   5. The control according to claim 4, wherein the adjustment unit changes at least one of the third threshold value, the fourth threshold value, the fifth threshold value, and the sixth threshold value according to an instruction signal input from the outside. apparatus.   2. The control device according to claim 1, wherein processing including operations of the power transmission information acquisition unit, the power reception information acquisition unit, the transmission state acquisition unit, and the adjustment unit is executed at regular intervals.   A wireless power transmission device comprising: a power transmission unit that generates a magnetic field with a coil; and a control device according to claim 1. The power transmission unit includes a power transmission unit including a coil and a capacity connected in series or in parallel to the coil, and means for supplying AC power to the power transmission unit,
11. The wireless power transmission device according to claim 10, wherein the power transmission unit generates a magnetic field in the coil from AC power.   A wireless power transmission device comprising: a power receiving unit that obtains power by magnetic field coupling with a magnetic field generated by the power transmission unit; and a control device according to claim 1. The power receiving unit includes an AC-DC converter that converts the received power into DC power, a DC-DC converter that converts the DC power, and a load that uses the power converted by the DC-DC converter. Including
13. The wireless power transmission apparatus according to claim 12, wherein the adjustment unit adjusts a voltage conversion ratio of the DC-DC conversion unit as the impedance adjustment process.   14. The wireless power transmission device according to claim 13, wherein the load is a battery. A power transmission information acquisition step for acquiring power transmission information representing at least one of the first power, the first voltage, and the first current of the first location in the power transmission unit that generates a magnetic field by the coil;
Power reception that acquires power reception information representing at least one of the second power, the second voltage, and the second current of the second location obtained by coupling the magnetic field with the coil of the power reception unit by the magnetic field generated in the power transmission unit An information acquisition step;
Based on the power transmission information and the power reception information, a transmission state acquisition step of acquiring a parameter representing a coupling state of the coil of the power transmission unit and the power reception unit;
In accordance with the parameter, an adjustment step of selecting and executing either one of a power transmission adjustment process for adjusting the first power of the power transmission unit and an impedance adjustment process for adjusting the impedance of the power receiving unit;
Control method with.

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