JP2013081275A - Contactless power feeding apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a contactless power feeding apparatus that can accurately detect a positional deviation of coils.SOLUTION: The contactless power feeding apparatus includes: measured value acquisition means 20 for acquiring measured values of voltage and current of a current flowing through a transmission apparatus 10; operation means 101 for storing a power feeding circuit theoretical expression including a coupling coefficient κ between a transmitting coil L1 of the transmission apparatus and a receiving coil L2 paired with the transmitting coil, to compute, from one of the measured values of voltage and current acquired by the measured value acquisition means and from the power feeding circuit theoretical expression, a theoretical value of the other of voltage and current of the current flowing through the transmission apparatus; and coil coupling state estimation means 100 for searching for such a coupling coefficient of the power feeding circuit theoretical expression as minimizes an error between the measured value of the other of voltage and current and the theoretical value of the other of voltage and current, and estimating a state of coupling between the transmitting coil and the receiving coil on the basis of such a coupling coefficient found.

Description

  The present invention relates to a non-contact power feeding device.

  The power transmission device includes a planar primary coil and a power reception device including a planar secondary coil. The power transmission device is connected to the power reception device by electromagnetically coupling the primary coil and the secondary coil. In a non-contact power transmission device that transmits power, a device that detects a positioning state based on an induced voltage of a secondary coil when positioning a primary coil and a secondary coil is known (Patent Document). 1).

JP 2006-60909 A

  However, since the conventional non-contact power feeding device detects the positioning state based on the induced voltage of the secondary coil, it becomes difficult to accurately measure the induced voltage when the induced voltage becomes small. There wasn't.

  The problem to be solved by the present invention is to provide a non-contact power feeding device that can accurately detect the amount of displacement of a coil.

  In the present invention, the difference between the theoretical value of the voltage value or current value calculated from one of the current value or voltage value of the power transmission coil and the circuit theoretical formula including the coupling coefficient and the measured value of the voltage value or current value is minimized. The above problem is solved by searching for the coupling coefficient of the circuit theoretical formula so that the positional deviation amount of the power transmission coil is obtained based on the searched coupling coefficient.

  According to the present invention, the coupling coefficient that minimizes the difference between the measured value and the theoretical value or the current value of the current value or voltage value of the power transmission coil can be obtained by calculation, and the coupling coefficient correlates with the positional deviation amount of the power transmission coil. The amount of positional deviation of the power transmission coil can be accurately detected.

It is a block diagram which shows the non-contact electric power feeding system to which one embodiment of this invention is applied. It is the top view and perspective view which show the state which the power transmission coil L1 and the receiving coil L2 of FIG. 1 opposed. It is the top view and perspective view which show the state which the power transmission coil L1 and the receiving coil L2 of FIG. 1 opposed, and is a figure which shows the case where it shift | deviates to the X-axis direction. 3 is a graph showing an example of a change in the coupling coefficient κ when the power receiving coil L2 shown in FIGS. 2A and 2B is displaced in the X-axis direction and the Z-axis direction. In FIG. 3, it is a graph which shows the relationship between the distance L between the power transmission coil L1 and the receiving coil L2, and the coupling coefficient (kappa). It is a graph for demonstrating the relationship between the position detection of a coil in a prior art, and a coupling coefficient. It is a graph which shows the relationship between the position of a coil, and charging efficiency. It is a graph which shows the relationship between the position of a coil and charging efficiency when the drive frequency of transmitted power fluctuates. It is the figure (the 1) which compared this example and the prior art about the estimation range of coupling coefficient (kappa). It is the figure (the 2) which compared this example and the prior art about the estimation possible range of coupling coefficient (kappa). It is a graph which shows the impedance characteristic with respect to coupling coefficient (kappa). FIG. 3 is a circuit diagram showing another embodiment of the resonance circuit of FIG. 1. It is a block diagram which shows the coil connection state estimation part of FIG. It is a flowchart which shows the control procedure of the coil connection state estimation part of FIG. FIG. 13 is a diagram (No. 1) for describing the control processing in steps S2 to S6 in FIG. 12; FIG. 13 is a diagram (No. 2) for describing the control process of steps S2 to S6 of FIG. 12; FIG. 13 is a diagram (No. 3) for illustrating the control processing in steps S2 to S6 in FIG. 12; It is a circuit diagram which shows the equivalent circuit for demonstrating a feeder circuit theoretical formula. It is a graph which shows the relationship between coupling coefficient (kappa) and voltage when a specific electric current value is substituted to a feeder circuit theoretical formula. It is a graph for demonstrating the brute force method used in (kappa) update part of FIG. 12 is a graph for explaining the Newton-Raphson method used in the κ update unit in FIG. 11. It is a graph for demonstrating the difference in the estimation precision of the coupling coefficient (kappa) by the measurement error of an electric current or a voltage. It is a graph which shows an example of the impedance characteristic with respect to the coupling coefficient of the output part of an inverter part, and the input part of a power transmission coil. It is a graph which shows the other example of the impedance characteristic with respect to the coupling coefficient of the output part of an inverter part, and the input part of a power transmission coil. It is a graph which shows the further another example of the impedance characteristic with respect to the coupling coefficient of the output part of an inverter part, and the input part of a power transmission coil. It is a block diagram which shows the non-contact electric power feeding system to which other embodiment of this invention is applied. It is a block diagram which shows the non-contact electric power feeding system to which further another embodiment of this invention is applied. It is a block diagram which shows the non-contact electric power feeding system to which further another embodiment of this invention is applied. It is a block diagram which shows the non-contact electric power feeding system to which further another embodiment of this invention is applied. It is a block diagram which shows the non-contact electric power feeding system to which further another embodiment of this invention is applied. FIG. 28 is a block diagram illustrating a combined state region determination unit in FIG. 27. It is a graph for demonstrating the difference in the estimation precision of the coupling coefficient (kappa) by the measurement error of an electric current or a voltage. It is a block diagram which shows the non-contact electric power feeding system to which further another embodiment of this invention is applied. It is a block diagram which shows the combined state area | region discrimination | determination part of FIG. It is a graph which shows an example which can suppress an estimation error by taking the average value of two coil connection state estimated values. It is a block diagram which shows the non-contact electric power feeding system to which further another embodiment of this invention is applied.

<< First Embodiment >>
FIG. 1 shows a non-contact power feeding system 1 to which an embodiment of the present invention is applied, which includes a power transmitting device 10 and a power receiving device 50, and is mounted on a vehicle or the like from a power transmitting device 10 installed on a power supply stand or the like. In this system, power is supplied to a load 53 such as a battery of the power receiving device 50 in a contactless manner and charged. In addition, the system which mounts the power transmission apparatus 10 and arrange | positions a power receiving apparatus on the ground may be sufficient.

The power transmission apparatus 10 of this example includes an AC power supply unit 11 such as a commercial power supply (frequency is 50 Hz in eastern Japan and frequency is 60 Hz in west Japan), and a DC power supply unit 12 that converts an AC voltage transmitted from the AC power supply unit 11 into a DC voltage. The voltage type inverter unit 13, the power transmission coil (primary coil) L ₁ for supplying the high frequency power output from the voltage type inverter unit 13 to the power receiving device 50 in a contactless manner, and the power transmission coil L ₁ are provided in parallel. A primary capacitor C _1P that constitutes a resonance circuit of the power transmission device 10.

The DC power supply unit 12 includes a diode D ₁ and a diode D ₂ , a diode D ₃ and a diode D ₄ , a diode D ₅ and a diode D ₆ , which are connected in parallel, and the AC power supply unit 11 is connected to each intermediate connection point. Three-phase output terminal is connected.

The voltage type inverter unit 13 includes diodes D _{7 to} D ₁₀ connected in reverse parallel to switching elements S _{1 to} S ₄ such as MOSFETs, and a DC voltage smoothing capacitor C _3. The output DC voltage is inversely converted to high frequency AC power of about 1 to 50 kHz.

Then, the intermediate connection point of the switching elements S ₁ and S _2, each of the intermediate connection point of the switching elements S ₃ and S _4, and the resonant circuit consisting of the power transmission coil L ₁ and the primary capacitor C _1P is connected Yes. Incidentally, also referred to as an intermediate connection point and the switching element S ₃ and S ₄ to the output of the high-frequency AC power source to a high frequency AC power terminal portion derived to the resonant circuit from the intermediate connection point between the switching element S ₁ and S _2.

The power receiving device 50 is provided in parallel with the power receiving coil (secondary coil) L ₂ that receives high-frequency AC power from the power transmitting coil L ₁ of the power transmitting device 10 in a non-contact state by electromagnetic induction, and the power receiving coil L ₂ receives power. a secondary capacitor C _2P constituting the resonant circuit of the apparatus 50, a rectifying unit 51 for rectifying a high-frequency AC power received by the receiving coil L _2, a smoothing capacitor C _4, a load 53 composed of a battery of the rechargeable battery And a relay switch 52 that cuts off / conducts power supply.

Rectifier 51 includes a diode _{D 11} and a diode _{D 12,} respectively of the diode _{D 13} and a diode _{D 14} are connected in parallel, the respective intermediate connection points, which is composed of a receiving coil _{L 2} and the secondary capacitor _{C 2P} The output terminal of the resonance circuit is connected. The output terminal of the rectifying unit 51 is connected to the load 53 via the relay switch 52.

  In addition, although illustration is abbreviate | omitted, the non-contact electric power feeding system 1 of this example is the control part which controls the voltage type inverter part 13 and the relay switch 52 other than the power transmission apparatus 10 and the power receiving apparatus 50 which were mentioned above, and the charge state of the load 53 A load control unit that generates a command value for charging power, a communication unit that transmits the power command value generated by the load control unit to the power transmission device 10, and that the user starts charging. A charging start switch for notifying the device is provided.

The control unit that controls the voltage type inverter unit 13 includes a current phase detection unit that detects the phase of the output current of the voltage type inverter unit 13 and a load control that monitors the charging state of the load 53 and generates a command value for charging power. A duty command generation unit (voltage amplitude command unit) for generating duty commands Dt ₁ and Dt ₂ of the voltage type inverter unit 13 from the load power command generated by the unit, and a voltage type inverter unit from the duty commands Dt ₁ and Dt ₂ A pulse generator that generates thirteen switching pulses.

The voltage type inverter unit 13 is controlled by the control unit as follows. That is, the duty command generation unit receives the load power command from the load control unit and generates duty commands Dt ₁ and Dt ₂ such that the power supplied to the load 53 matches the command value from the load control unit. . Next, PWM modulation is performed using a triangular wave carrier comparison method or the like, and the generated duty commands Dt ₁ and Dt ₂ are compared with the triangular wave carrier to generate control pulses for the switching elements S _{1 to} S ₄ .

  Furthermore, the non-contact power feeding system 1 of this example includes a coil coupling state estimation unit 100, which includes a theoretical value calculation unit 101, an error calculation unit 102, an error comparison unit 103, and a κ update unit 104. including.

The theoretical value calculation unit 101 includes a voltage detected by the detection unit 20 provided between the voltage-type inverter unit 13 and the resonance circuit (the power transmission coil L ₁ and the primary capacitor C _1P ), that is, the output unit of the high-frequency AC power supply. The measured current value is input, and is sequentially output from the κ candidate value a to the error calculator 102 as the theoretical value of the coupling coefficient κ.

  The error calculation unit 102 calculates an error between the voltage and current measurement values detected by the detection unit 20 and the theoretical value calculated by the theoretical value calculation unit 101, and outputs the error to the error comparison unit 103. The error comparison unit 103 compares the error calculated by the error calculation unit 102 with the error allowable value, and when the condition is satisfied, outputs the κ estimated value a as the coil coupling state estimated value to the outside, while satisfying the condition. If not, the κ candidate value b is output to the κ update unit 104. If the result of the comparison by the error comparison unit 103 does not satisfy the condition, the κ update unit 74 sequentially updates the κ candidate value a to the next b, c... until the condition is satisfied. Details of the operation of the coil coupling state estimation unit 100 will be described later.

  Next, with reference to FIG. 2A, FIG. 2B, FIG. 3 and FIG. 4, it will be described that the coupling coefficient κ between the power transmission coil L1 and the power reception coil L2 changes. 2A and 2B are a plan view a) showing a state in which the power transmission coil L1 and the power reception coil L2 face each other, and perspective views b) and c). 2A and 2B, the X axis and the Y axis indicate planar directions of the power transmitting coil L1 and the power receiving coil L2, and the Z axis indicates the height direction. For the purpose of this description, the power transmission coil L1 and the power reception coil L2 are both formed in the same circular shape, but in this example, it is not always necessary to have a circular shape, and the power transmission coil L1 and the power reception coil L2 have the same shape. There is no need to make it.

  Now, assuming that the power transmission coil L1 is on the ground and the power reception coil L2 is mounted on the vehicle, as shown in FIG. 2A, the power reception coil L2 matches the power transmission coil L1 in the X-axis and Y-axis directions which are planar directions. However, depending on the skill of the driver, the relative positions of the power transmission coil L1 and the power reception coil L2 may be shifted in the plane direction, as shown in FIG. 2B. is there. Further, since the height of the vehicle varies depending on the type of vehicle and the load, the distance in the height direction Z between the power transmission coil L1 and the power reception coil L2 also varies depending on the vehicle height.

  FIG. 3 shows an example of a change in the coupling coefficient κ for the power receiving coil L2 in the X-axis direction and the Z-axis direction shown in FIGS. 2A and 2B. As shown in FIG. 3, when the center of the power transmission coil L1 coincides with the center of the power reception coil L2 (the value of the X axis in FIG. 3 corresponds to zero), leakage between the power transmission coil L1 and the power reception coil L2 The magnetic flux is small and the coupling coefficient κ is large (κ = 0.8 in the example in the figure). On the other hand, when the positions of the power transmission coil L1 and the power reception coil L2 are shifted in the X-axis direction (or the height in the Z-axis direction is changed), the leakage magnetic flux increases, and the coupling coefficient κ decreases as shown in FIG. (In the example of the figure, κ = 0.1).

FIG. 4 is a graph showing the relationship between the distance L between the power transmission coil L1 and the power reception coil L2 and the coupling coefficient κ. The distance L is the plane of the power reception coil L2 shown in FIGS. 2A, 2B and FIG. Using the direction X-axis and the height direction Z-axis, L = √ (X ² + Z ² ) is defined. In this case, the power transmission coil L1 is fixed, and is the distance of the power reception coil L2 with respect to the power transmission coil L1. The coupling coefficient κ gradually approaches 1 as the distance L approaches zero, while the coupling coefficient κ gradually approaches zero as the distance L increases.

  By the way, since the distance between the power transmission coil L1 and the power reception coil L2 does not move relative to the non-contact power feeding device that is used for charging a cordless household appliance such as an electric toothbrush or a shaving shaver or a portable device, It is not necessary to assume that the coupling coefficient κ varies. Therefore, in such a conventional non-contact power feeding system, as shown in FIG. 5A, it is sufficient to determine whether or not the positions of the power transmitting coil and the power receiving coil are within a predetermined range based on one threshold value.

  In addition, since the above-described home appliances and portable devices can be positioned easily with a small charge power, precise position detection between the power transmission coil and the power reception coil is unnecessary. For this reason, in the said prior art, the positional relationship of a coil can be estimated using the induced voltage of a receiving side coil. However, as shown in FIG. 5B, the conventional technique has a problem that position detection cannot be performed when the coupling state of the coils is weak, and the position detection range is limited to a narrow range.

On the other hand, as described above, when the power transmission coil L1 is installed on the ground (infrastructure side), the power reception coil L2 is mounted on the vehicle, and the battery 53 of the vehicle is charged without contact, the vehicle is stopped. The coupling coefficient κ (distance L) varies greatly depending on the state and the vehicle height state. When the coupling coefficient κ (distance L) varies, the charging efficiency varies greatly as shown in FIG. 6A, which may adversely affect the charging time and power consumption. 6A also varies depending on the driving frequencies f ₀ , f ₁ , f ₂ ... Of the high-frequency AC power of the power transmission device 10 as shown in FIG. 6B. Therefore, unless the positional relationship between the power transmission coil L1 and the power reception coil L2, that is, the coupling state can be detected, the charging efficiency and the optimal drive frequency of the inverter unit 13 cannot be grasped. In other words, if the positional relationship of the coils, that is, the coupling state can be detected, the charging efficiency can be grasped, and the inverter unit 13 can be operated at the optimum driving frequency.

  FIG. 7 is a diagram showing a range in which the coil position (= coupled state) of this example and the conventional example can be estimated. Since the conventional example uses the induced voltage of the receiving coil L2 for estimation as described above, the coil position (= coupled state) cannot be estimated within the range where the induced voltage cannot be detected. On the other hand, in this example, since the coupling state estimation of the coils L1 and L2 is performed from the measured values of the current and voltage of the power transmission device 10, even in a range where the coil misalignment is large, that is, the coupling coefficient κ is close to zero. The deviation can be estimated.

  FIG. 8 is a diagram showing a comparison between this example and the conventional example. In the conventional examples 1 and 2, the coil position (= coupled state) is estimated by setting one threshold within the estimable range. For this reason, it is only possible to determine whether or not the coil is within a specific range. In contrast, in this example, since the coil coupling state is estimated from the error between the measured value and the theoretical value without using one threshold value, linear estimation is possible as shown in FIG. In the conventional example, linear estimation is possible by finely setting the threshold value, but in such a case, each threshold value must be set for each coil position. In addition, since the threshold value changes depending on the load state of the battery, a large amount of memory is required to set so as to satisfy all the conditions, leading to a cost increase.

Next, the principle of estimating the coil coupling state of this example will be described. Here, as an example, the capacitors C _1P and C _2P are inserted in parallel with the power transmission coil L1 and the power reception coil L2 in both the power transmission side resonance circuit and the power reception side resonance circuit, but the configuration of the resonance circuit is not limited to this. The one shown in FIG. 10 can be adopted. That is, as shown in a) and b) of FIG. 10, a resonant circuit in which capacitors C _1P and C _2P are connected in series to the power transmission coil L1 or the power receiving coil L2, or as shown in c) and d) of FIG. Instead of the capacitors C _1P and C _2P , a resonance circuit in which a coil or a transformer is connected in series or in parallel can be adopted.

  Since the self-inductance and the mutual inductance of the power transmission coil L1 and the power reception coil L2 change due to the change of the coupling coefficient κ, the impedance of the load side viewed from the power transmission side resonance circuit is changed by the coupling coefficient κ. As an example of this, FIG. 9 shows the characteristics of the absolute value of the impedance with respect to the coupling coefficient κ when the load side is viewed from the output portion of the high-frequency AC power supply (the position where the detection unit 20 of FIG. From this, it can be seen that there is a correlation between the coupling coefficient κ and the impedance (voltage, current value) on the power transmission device 10 side. Therefore, it is possible to estimate the coupling state of the coils L1 and L2 by measuring the impedance of the power transmission device 10.

  FIG. 11 is a block diagram illustrating an example of the coil coupling state estimation unit 100 of FIG. As described above, the coil coupling state estimation unit 100 includes the theoretical value calculation unit 101, the error calculation unit 102, the error comparison unit 103, and the κ update unit 104.

The theoretical value calculation unit 101 stores a theoretical relational expression (hereinafter also referred to as a power supply circuit theoretical expression) of the coupling coefficient κ, current, and voltage. In the equivalent circuit of the non-contact power feeding system 1 shown in FIG. 16A, assuming that the voltage value of the current flowing through the power transmitting device 10 is V, the current value is I, and the coupling coefficient between the power transmitting coil L1 and the power receiving coil L2 is κ, The theoretical relational expression of the current value and the coupling coefficient is expressed by an impedance equation that is a ratio of current to voltage as shown in Equation 1 below. In Equation 1, A to G are known parameters determined by the capacitors C _1P and C _2P , coils L ₁ and L ₂ , and load resistance RL shown in FIG. 16A.

  That is, in the equivalent circuit of the non-contact power feeding system 1 shown in FIG. 16A, the current I and the voltage V flowing through the power transmission device 10 vary depending on the coupling coefficient κ between the power transmission coil L1 and the power reception coil L2, and for example, as shown in FIG. When a specific current is passed through the power transmission device 10, the voltage at that time varies depending on the coupling coefficient κ. In other words, if the voltage and current of the current flowing through the power transmission device 10 are measured, the coupling coefficient κ can be obtained by calculation using the above power supply circuit theoretical formula. Note that the power supply circuit theoretical formula stored in the theoretical value calculation unit 101 can use an admittance formula representing the ratio of voltage to current in addition to the impedance formula of Formula 1 above, and is a simpler simulator. Also good.

  Returning to FIG. 11, the theoretical value calculation unit 101 receives the κ candidate value a output from the κ update unit 104 and the measured value of the voltage detected by the detection unit 20 as input, and calculates the theoretical value (calculated value) of the current. Output to the error calculator 102. The error calculation unit 102 receives the current theoretical value calculated by the theoretical value calculation unit 101 and the current measurement value detected by the detection unit 20, and outputs an error of the current to the error comparison unit 103.

  The error comparison unit 103 receives the current error calculated by the error calculation unit 102, the κ candidate value a output from the κ update unit 104, and a predetermined current error allowable value (range) as inputs. It is determined whether the κ candidate value a is valid. That is, when the current error calculated by the error calculation unit 102 is the current error allowable value (range), the κ candidate value a that is a premise is assumed to be an appropriate value, and the κ candidate value a is Output as estimated coil coupling state. On the other hand, if the current error calculated by the error calculation unit 102 is not the current error allowable value (range), it is determined that the κ candidate value that is the premise is not an appropriate value, and the κ candidate value Instead of a, a new κ candidate value b is output to the κ update unit 104. The κ update unit 104 receives the κ candidate value b output from the error comparison unit 103, and updates the current κ candidate value a to the next κ candidate value b.

  FIG. 12 shows a flowchart of the coil coupling state estimation. First, the voltage and current of the current flowing through the power transmission device 10 are measured by the detection unit 20 (step S1), and the initial κ candidate value a and the error allowable value are read (step S2). Next, the theoretical value of the current is calculated by substituting the measured voltage value and the initial κ candidate value into the theoretical formula of the feeder circuit (step S3). Then, an error value between the theoretical value of the current and the measured value of the current is calculated (step S4), and it is determined whether or not the error value is equal to or less than an allowable error value (step S5). If the error value is not equal to or smaller than the allowable error value in step S5, the initial κ candidate value is updated to the next κ candidate value (step S6), and the process returns to step S3, and step S3 is performed until the error value becomes equal to or smaller than the allowable error value. ˜S6 is repeated to update the κ candidate value. When the error value in step S4 becomes equal to or less than the allowable error value (ideally zero), the updating is stopped, and the κ candidate value a at that time is output as the coil coupling state estimated value to complete the estimation (step S7).

  The κ estimation process in steps S2 to S6 in FIG. 12 will be schematically described with reference to FIGS. Note that the error tolerance is zero. FIG. 13 shows a state at an initial κ candidate value (here, κ = 0). In the initial κ candidate value a, the error value is larger (not zero) than the allowable error value, which means that the coil coupling state estimated value is not obtained. Therefore, the κ candidate value is updated.

  Next, FIG. 14 shows a state in which the κ candidate value is updated. Although the error value is smaller than the initial κ candidate value, it is still larger than the allowable error value. Therefore, the κ candidate value is further updated. FIG. 15 shows a state where the κ candidate value is equal to the true value of κ. In this state, the measured current value is equal to the theoretical value, and the error value is zero. Therefore, the condition of the allowable error value is satisfied, and the κ candidate value at this time becomes the coil coupling state estimated value.

  In order to update the κ candidate value, a brute force method as shown in FIG. 17 or a Newton-Raphson method as shown in FIG. 18 may be used. In the round robin method shown in FIG. 17, the coupling coefficient κ is swept at predetermined intervals in the range of 0 to 1 (κ0, κ1,..., Κn), and the coupling coefficient (κ3 in the figure) with the smallest error is searched. This is a calculation method. Further, the Newton-Raphson method shown in FIG. 18 is an arithmetic method for searching for the most probable κ by using the slope. First, the slope at the initial value κ0 is obtained, and the X-axis intercept (κ1) is obtained from this slope. The error of the X-axis intercept κ1 is calculated to determine whether or not it is less than the allowable error value. If it is less than the allowable error value, κ1 is used as an estimated value. The X-axis intercept (κ2) is determined from this gradient, and this is repeated sequentially to search for a coupling coefficient (κ3 in the figure) with the smallest error.

  In the above example, the theoretical value of the current is calculated from the measured value of the voltage, and the coupling coefficient κ is estimated from the error between the measured value of the current and the theoretical value of the current. The theoretical value of the voltage may be obtained by substituting it into the circuit theoretical formula, and the coupling coefficient κ may be estimated from the error between the theoretical value of the voltage and the measured value of the voltage. Further, the impedance error may be obtained by comparing the measured value of the impedance on the left side of the power supply circuit theoretical formula with the theoretical value of the impedance, and the coupling coefficient κ may be estimated from this.

  As described above, according to the contactless power feeding system 1 of this example, when the distance between the power transmission coil L1 and the power receiving coil L2 is large and the coupling coefficient κ is close to 0 (coupling is weak), the power transmission apparatus 10 side is disabled. Since the power increases, the change is easily detected. Therefore, even when the coil coupling is weak, the coil coupling state can be estimated. Further, since the coupling coefficient κ estimated in this case is not a discrete numerical value but a continuous numerical value as described with reference to FIG. 8, the estimation accuracy of the coupling coefficient κ increases. As a result, the amount of positional deviation between the power transmission coil L1 and the power reception coil L2 can be detected with high accuracy, so that the charging efficiency can be increased as shown in FIG. 6A, and the charging efficiency is improved as shown in FIG. 6B. A high driving frequency can be set.

  Further, according to the non-contact power feeding system 1 of this example, since the coupling state of the coil is estimated on the power transmission device 10 side, compared to estimating the coupling state of the coil on the power reception device 50 side, Communication time required for feedback is shortened. For this reason, when the position of the coil changes during charging and an emergency stop is required, an immediate countermeasure can be taken.

<< Second Embodiment >>
The coil coupling state estimation unit 100 of the first embodiment can theoretically perform estimation with zero estimation error. However, actually, an error occurs in the measurement system, and an estimation error occurs due to the influence. The influence of this measurement error on estimation will be described with reference to FIG. In the figure, “◯” represents the measured value 1 of the coupling coefficient κ1, “×” represents the measured value 2 of κ2, and the solid line represents the theoretical impedance value in the theoretical equation.

  The measurement error is expressed by a deviation (ΔZ1) from a theoretical value on the same κ axis. First, the measurement value 1 is considered for the influence of the measurement error on the estimation. The result of measuring the impedance in the state of κ1 is the measured value 1. Κ having the same impedance as the measurement value 1 is an estimated value (here, κ1 ′), and the estimation error is κ1−κ1 ′. That is, the influence of the measurement error ΔZ1 on the estimation is κ1-κ1 ′. Similarly, when the measurement value 2 is considered, the influence of the measurement error ΔZ2 on the estimation is κ2−κ2 ′.

  Here, when the estimation errors of the two measured values 1 and 2 are compared, it is understood that the error of the measured value 2 is large. That is, in the region where the impedance change is steep with respect to the coupling coefficient κ as in the vicinity of the measurement value 1, the influence of the measurement error is small, but in the region where the impedance characteristic is flat like the measurement value 2, the influence of the measurement error is. growing.

  Now, FIG. 20 shows the output part of the inverter part 13 (the part of the detection part 20 in FIG. 1) and the impedance characteristic of the power transmission coil L1. From this, it is understood that the region where the impedance characteristic is steep differs depending on the coupling coefficient κ between the high-frequency AC power supply units 11, 12, and 13 of the power transmission device 10 and the power transmission coil L <b> 1. 21 and 22 show the impedance characteristics of the power transmission device 10 and the power reception device 50 shown in FIG. Although there are differences in the general shape and size of the characteristics, it is understood that the region where the amount of change is large differs between the high-frequency AC power supplies 11, 12, 13 and the power transmission coil L1. Therefore, in this example, as described below, the configuration using the characteristics of the high-frequency AC power supply units 11, 12, and 13 and the power transmission side coil L1 described above is used.

  FIG. 23 is a non-contact power feeding system 1 to which the second embodiment (part 1) of the present invention is applied. Although there is no difference in the drawing compared to the non-contact power feeding system 1 shown in FIG. The difference is that the current and voltage measurement value detection unit 20 used for estimation is limited to the high-frequency AC power supply unit, in other words, the output unit of the inverter unit 13. Since other configurations are the same as those of the first embodiment described above, description thereof is omitted.

  Since the circuit configurations of the power transmission device 10 and the power reception device 50 are determined at the time of design, it is possible to grasp the impedance characteristics of the output unit of the inverter unit 13 of the high-frequency AC power supply unit in advance. Therefore, it is possible to grasp a region where the impedance characteristic is steep at the time of design, that is, a region where the estimation error is small. If this area matches the area to be used, the current and voltage of the output part of the inverter part 13 of the high-frequency AC power supply part may be detected.

  As shown in FIG. 3, the coupling coefficient κ also changes depending on the height. That is, when considering application to a vehicle, the maximum value of the coupling coefficient κ may be 0.4 or 0.1 depending on the vehicle height even if the lateral displacement is zero. As described above, since the region of the coupling coefficient κ requiring high estimation accuracy differs depending on the design (vehicle), if the narrow region where the impedance characteristic is steep matches the region used in this way, Thus, only the current and voltage at the output section of the inverter section 13 need be detected.

  FIG. 24 is a non-contact power feeding system 1 to which the second embodiment (No. 2) of the present invention is applied, and is used for estimating the coupling coefficient κ compared to the non-contact power feeding system 1 shown in FIGS. 1 and 23. The difference is that the voltage and current measurement value detection unit 21 is limited to the input unit of the power transmission coil L1. Since other configurations are the same as those of the first embodiment described above, description thereof is omitted. For the same reason as described above, when the region where the estimation error is small coincides with the region to be used, the voltage and current of the input unit (detection unit 21) of the power transmission coil L1 may be detected.

  FIG. 25 is a non-contact power feeding system 1 to which the second embodiment (No. 3) of the present invention is applied. Compared with the non-contact power feeding system 1 shown in FIGS. Voltage and current measurement value detection unit 20, coil coupling state estimation unit 100 a that inputs the measurement value, voltage and current measurement value detection unit 21 of the input part of power transmission coil L 1, and measurement value thereof Is different from the coil coupling state estimation unit 100b.

  In this example, by outputting the coil coupling state estimation units 100a and 100b, it is possible to estimate the coil coupling state with high accuracy from a weak coil coupling state to a strong range. How to handle the two coil coupling state estimation values a and b will be described later.

<< Third Embodiment >>
In this example, the voltage and current used as measured values for the estimation of the coupling coefficient κ shown in FIG. This is a system configuration that detects both, and is an embodiment of how to handle two obtained coil coupling state estimation values a and b.

  As described above, if the impedance characteristic is steep with respect to the coupling coefficient κ, the influence of the measurement error on the estimated value can be suppressed. In other words, as the absolute value of the slope of the impedance curve with respect to the coupling coefficient κ shown in FIG. 19 and the like is relatively large, the estimated value error is relatively small even if the measurement error is large. In this example, the respective impedance characteristics of the output section (detection section 20) of the inverter section 13 and the input section (detection section 21) of the power transmission coil L1 are used. If the steep region can be discriminated, the size of the estimation error can be discriminated.

  Therefore, in this example, this region is determined by detecting the power factor of the output unit (detection unit 20) of the inverter unit 13 of the high-frequency AC power supply. The power factor increases when the impedance of the output section of the inverter unit 13 is maximized (or minimized), and decreases when the impedance deviates from the maximum (or minimized). That is, there is a correlation between the impedance and the power factor of the output unit of the inverter unit 13. Based on this relationship, a threshold value is provided for the power factor, and it is determined from this threshold value which estimation error of the coil coupling state estimation value is small.

  FIG. 26 is a block diagram showing the non-contact power feeding system 1 of this example. The difference from the non-contact power feeding system 1 according to the second embodiment of FIG. 25 is that the detection unit 20 detects the power factor of the output unit of the inverter unit 13 (the ratio of the active power P to the apparent power S = P / S). A combined state region discriminating unit 200 is added which receives the power factor, power factor threshold value, and coil coupling state estimation values a and b as inputs, discriminates one having a small estimation error and outputs one coil coupling state estimation value. Is a point.

  In this example, the combined state region discriminating unit 200 inputs measured values of voltage and current from the detecting unit 20 that is the output unit of the inverter unit 13, and calculates the power factor P / S therefrom. Here, if the phase difference between the voltage and the current in the detection unit 20 is θ, the power factor P / S = cos θ, and the phase difference θ between the voltage and the current can be detected from the voltage waveform and the current waveform from the detection unit 20. The power factor P / S can be calculated.

  When the power factor is large, the impedance of the output unit (detection unit 20) of the inverter unit 13 is maximized or minimized, and when the power factor is small, the impedance is deviated from the maximum or minimum. When the power factor of the output part of the inverter unit 13 obtained from the voltage and current measured in this way is large, the impedance becomes maximum or minimum. Accordingly, in this case, as described with reference to FIG. 19, the estimation error of the coupling coefficient κ due to the measurement error is reduced, so that the coil using the measured values of the voltage and current of the output unit (detection unit 20) of the inverter unit 13 is used. The combined state estimated value a is adopted, and this is output as the final coil combined state estimated value. As a result, it is possible to output an estimated value that is less influenced by the measurement error, and the accuracy of the coupling coefficient κ, and hence the positional deviation amount between the power transmission coil L1 and the power reception coil L2, is improved.

  On the contrary, when the power factor of the output unit of the inverter unit 13 obtained from the voltage and current measured by the detection unit 20 is small, the impedance deviates from the maximum or the minimum. Accordingly, in this case, as described with reference to FIG. 19, the estimation error of the coupling coefficient κ due to the measurement error becomes large, and conversely, the impedance of the input part of the power transmission coil L1 becomes maximum or minimum and the coupling coefficient κ due to the measurement error. Therefore, the coil coupling state estimated value b using the measured values of the voltage and current of the input unit (detecting unit 21) of the power transmission coil L1 is adopted, and this is used as the final coil coupling state estimated value. Output. As a result, it is possible to output an estimated value that is less influenced by the measurement error, and the accuracy of the coupling coefficient κ, and hence the positional deviation amount between the power transmission coil L1 and the power reception coil L2, is improved. Further, since the coupling state estimation values a and b that are less affected by the measurement error can be discriminated, the detection accuracy of the coil coupling state can be increased over a wide range.

<< 4th Embodiment >>
In this example, the voltage and current used as measured values for the estimation of the coupling coefficient κ shown in FIG. This is a system configuration that detects both of them, and is another embodiment of how to handle the obtained two coil coupling state estimation values a and b with respect to the third embodiment.

  In the third embodiment, the power factor of the output unit (detection unit 20) of the inverter unit 13 is detected, and the estimation accuracy of the two coil coupling state estimation values a and b is determined from this power factor. By comparing the magnitudes of the impedances of the detection units 20 and 21, it is determined whether the estimation error is small. That is, as shown in FIG. 19, it can be seen that the region where the impedance characteristic is steep is larger than the one in terms of the magnitude of the impedance. Using this characteristic, a region having a steep impedance characteristic is discriminated, and a region having a smaller estimation error is discriminated.

  FIG. 27 is a block diagram showing the non-contact power feeding system 1 of this example. The difference from the non-contact power feeding system 1 according to the second embodiment of FIG. 25 is that the voltages and currents of the detection units 20 and 21 and the coil coupling state estimation values a and b are input and the coil coupling state estimation value is output. This is the point that a combined state region discriminating unit 200 is added.

  FIG. 28 is a block diagram showing the coupled state region discriminating unit 200 of FIG. 27, in which an impedance calculation unit 201 that calculates the magnitude of the impedance from the measured values of the voltage and current of the detection unit 20, and the voltage and An impedance calculation unit 202 that calculates the magnitude of the impedance from the measured current value, an impedance comparison unit 203 that compares the magnitude of the impedance from the outputs of the impedance calculation units 201 and 202, and a coil coupling state estimated value from the comparison result a coil coupling state determination unit 204 that determines which of the estimation errors a and b is smaller and outputs an estimated coil coupling state value.

  As described above, the region where the impedance characteristic is steep as shown in FIG. 19 has a larger impedance than the other. Therefore, the larger the impedance of the detection units 20 and 21, the greater the influence of the estimated value due to the measurement error. Few. Therefore, in the coil coupling state determination unit 204, when the impedance of the detection unit 20 is larger, the coil coupling state estimation value a based on the voltage and current measurement values of the detection unit 20 is used as the coil coupling state estimation value. Select and output. Conversely, when the impedance of the detection unit 21 is larger, the coil coupling state estimation value b based on the voltage and current measurement values of the detection unit 21 is selected and output as the coil coupling state estimation value. As a result, it is possible to output an estimated value that is less influenced by the measurement error, and the accuracy of the coupling coefficient κ, and hence the positional deviation amount between the power transmission coil L1 and the power reception coil L2, is improved. Further, since the coupling state estimation values a and b that are less affected by the measurement error can be discriminated, the detection accuracy of the coil coupling state can be increased over a wide range.

<< 5th Embodiment >>
In this example, the voltage and current used as measured values for the estimation of the coupling coefficient κ shown in FIG. This is a system configuration for detecting both of them, and is still another embodiment of how to handle the obtained two coil coupling state estimation values a and b with respect to the third embodiment.

  In the third embodiment, the power factor of the output unit (detection unit 20) of the inverter unit 13 is detected, and the estimation accuracy of the two coil coupling state estimation values a and b is determined from this power factor. By comparing the differential values of the impedances of the detectors 20 and 21, it is determined whether the estimation error is small. That is, FIG. 29 shows the slope (differential value) of the impedance characteristics in the estimated values of the small and large estimation errors. As described above, the slope (absolute value of the differential value) increases when the impedance characteristic is steep and the estimation error is small. That is, the magnitude of the error can be determined by comparing the absolute value of the differential value of the impedance characteristic in the estimated value.

  FIG. 30 is a block diagram showing the non-contact power feeding system 1 of this example. The difference from the non-contact power feeding system 1 according to the second embodiment of FIG. 25 is that a coupling state region discriminating unit 200 that receives the coil coupling state estimation values a and b and outputs the coil coupling state estimation value is added. is there.

  FIG. 31 is a block diagram showing the coupling state region discriminating unit 200 of FIG. 30, a differential value calculation unit 211 that receives the coil coupling state estimation value a and outputs a differential value of the impedance of the detection unit 20, and coil coupling The differential value calculation unit 212 that receives the state estimated value b as an input and outputs the differential value of the impedance of the detection unit 21, determines the magnitude of the differential value from the output, and outputs the differential value having the larger absolute value A value comparison unit 213; and a coil coupling state determination unit 214 that receives the output and the coil coupling state estimation values a and b and outputs a coil coupling state estimation value having a larger absolute value of the differential value.

  As described above, when the impedance characteristic is steep and the estimation error is small, the absolute value of the differential value is large. Therefore, when the absolute value of the differential value of the impedance of the detection units 20 and 21 is large, the estimation value is affected by the measurement error. Few. Therefore, in the coil coupling state determination unit 214, when the absolute value of the differential value of the impedance of the detection unit 20 is larger, the coil coupling state estimation value a based on the voltage and current measurement values of the detection unit 20 is calculated. Select as coil connection state estimated value and output. On the contrary, when the absolute value of the differential value of the impedance of the detection unit 21 is larger, the coil coupling state estimated value b based on the voltage and current measurement values of the detection unit 21 is selected as the coil coupling state estimated value. ,Output. As a result, it is possible to output an estimated value that is less influenced by the measurement error, and the accuracy of the coupling coefficient κ, and hence the positional deviation amount between the power transmission coil L1 and the power reception coil L2, is improved. Further, since the coupling state estimation values a and b that are less affected by the measurement error can be discriminated, the detection accuracy of the coil coupling state can be increased over a wide range.

<< 6th Embodiment >>
In this example, the voltage and current used as measured values for the estimation of the coupling coefficient κ shown in FIG. This is a system configuration for detecting both of them, and is still another embodiment of how to handle the obtained two coil coupling state estimation values a and b with respect to the third embodiment.

  In the third embodiment, the power factor of the output unit (detection unit 20) of the inverter unit 13 is detected, and the estimation accuracy of the two coil coupling state estimation values a and b is determined from this power factor. By averaging the two coil coupling state estimation values a and b, the influence of the estimation error is suppressed.

  That is, FIG. 32 shows an example in which an estimation error can be suppressed by taking an average value. Κ1 ′ and κ2 ′ are the results of estimation in a coil coupling state in which two impedance characteristics are targets for κ and the impedance characteristics intersect. In this situation, the two estimation errors are κ-κ1 ′ and κ-κ2 ′, which are equal to each other. If an average value is taken, a coil coupling state estimation value with no estimation error can be obtained. In addition, if the measurement accuracy is high and the estimation error is sufficiently small, it is possible to obtain a more accurate coil coupling state estimation value by taking an average value.

  FIG. 33 is a block diagram showing the non-contact power feeding system 1 of this example. The difference from the non-contact power feeding system 1 according to the second embodiment of FIG. 25 is that the coupled state region discriminating unit 200 that receives the coil coupled state estimated values a and b and outputs the average value as the coil coupled state estimated value. This is an added point.

  As described above, if the two coil coupling state estimation values a and b are averaged, the respective errors are also reduced, so that it is possible to output an estimation value that is less affected by the measurement error, and the coupling coefficient κ and, consequently, the power transmission coil L1. The accuracy of the positional deviation amount of the power receiving coil L2 is improved.

  The detection units 20 and 21 correspond to the measurement value acquisition unit according to the present invention, the theoretical value calculation unit 101 corresponds to the calculation unit according to the present invention, and the error calculation unit 102, the error comparison unit 103, and the κ update unit. Reference numeral 104 corresponds to the coil coupling state estimation unit according to the present invention, and the coupling state region determination unit 200 corresponds to the coupling region determination unit according to the present invention.

1 ... non-contact power supply system 10 ... power transmission apparatus 11 ... AC power supply unit 12 ... DC power supply 13 ... voltage type inverter unit D ₁ to D _{10 ...} diodes C _1P, C ₃ ... capacitors S ₁ to S ₄ ... MOSFET
L ₁ ... power transmission coil 50 ... power receiving device L ₂ ... power receiving coils D _{11 to} D ₁₄ ... diode C ₄ , C _2P ... capacitor 51 ... rectifier 52 ... relay switch 53 ... load 100 ... coil coupling state estimation unit 101 ... theoretical value Calculation unit 102 ... Error calculation unit 103 ... Error comparison unit 104 ... κ update unit 200 ... Combined state region determination unit

Claims (9)

A measurement value acquisition means for acquiring a voltage of the current flowing through the power transmission device and a measurement value of the current;
A power feeding circuit theoretical formula including a coupling coefficient between a power transmission coil of the power transmission device and a power receiving coil paired with the power transmission coil is stored, and one measured value of the voltage and current acquired by the measured value acquisition unit and the From the feeder circuit theoretical formula, a calculation means for calculating the other theoretical value of the voltage and current of the current flowing through the power transmission device,
A search is made for a coupling coefficient of the feeder circuit theoretical formula so that an error between the other measured value of the voltage and current and the other theoretical value of the voltage and current is minimized, and based on the searched coupling coefficient. A non-contact power feeding apparatus comprising: a coil coupling state estimation unit that estimates a coupling state between the power transmission coil and the power reception coil. The coil coupling state estimation means includes
An error calculator that calculates an error between the other measured value of the voltage and current and the other theoretical value of the voltage and current;
An error comparison unit that compares the error calculated by the error calculation unit with an allowable value;
The non-contact electric power feeder of Claim 1 provided with the coupling coefficient update part which updates the coupling coefficient of the said electric power feeding circuit theoretical formula until the said error becomes below the said tolerance. The power transmission device includes a high-frequency AC power source that supplies high-frequency AC power to a resonance circuit unit including the power transmission coil,
The non-contact power feeding apparatus according to claim 1, wherein the measurement value acquisition unit acquires only measurement values of voltage and current of an output unit of the high-frequency AC power supply.   The non-contact power feeding apparatus according to claim 1, wherein the measurement value acquisition unit acquires only measurement values of voltage and current of an input unit in which high-frequency AC power is input to the power transmission coil. The power transmission device includes a high-frequency AC power source that supplies high-frequency AC power to a resonance circuit unit including the power transmission coil,
The measurement value acquisition means includes
Measurement values of voltage and current at the output of the high-frequency AC power source,
The non-contact power feeding device according to claim 1, wherein both a voltage value and a current measurement value of an input unit into which high-frequency AC power is input to the power transmission coil are acquired. A coupling state estimation value A estimated by the coil coupling state estimation means based on measured values of voltage and current at the output of the high-frequency AC power source;
A coupling state estimation value B estimated by the coil coupling state estimation means based on the measured values of the voltage and current of the input unit to which high-frequency AC power is input to the power transmission coil;
The power factor of the output section of the high-frequency AC power supply;
Further comprising a combined region discriminating means for obtaining
6. The non-contact power feeding according to claim 5, wherein the coupling region discriminating unit outputs one of the coupling state estimation value A and the coupling state estimation value B in accordance with a power factor of an output unit of the high-frequency AC power source. apparatus. A coupling state estimation value A estimated by the coil coupling state estimation means based on measured values of voltage and current at the output of the high-frequency AC power source;
A coupling state estimation value B estimated by the coil coupling state estimation means based on the measured values of the voltage and current of the input unit to which high-frequency AC power is input to the power transmission coil;
The impedance of the output section of the high-frequency AC power supply;
The impedance of the input section where high frequency AC power is input to the power transmission coil;
Further comprising a combined region discriminating means for obtaining
The non-contact power feeding device according to claim 5, wherein the coupling region determination unit outputs one of the coupling state estimation value A and the coupling state estimation value B according to an absolute value of the two impedances. A coupling state estimation value A estimated by the coil coupling state estimation means based on measured values of voltage and current at the output of the high-frequency AC power source;
A coupling state estimation value B estimated by the coil coupling state estimation means based on the measured values of the voltage and current of the input unit to which high-frequency AC power is input to the power transmission coil;
The differential value of the impedance of the output part of the high-frequency AC power supply,
The differential value of the impedance of the input part where high frequency alternating current power is input to the power transmission coil,
Further comprising a combined region discriminating means for obtaining
The said coupling area | region discrimination | determination means outputs any one of the said coupling | bonding state estimated value A and the said coupling | bonding state estimated value B according to the magnitude | size of the absolute value of the differential value of the said two impedance. Non-contact power feeding device. A coupling state estimation value A estimated by the coil coupling state estimation means based on measured values of voltage and current at the output of the high-frequency AC power source;
A coupling state estimation value B estimated by the coil coupling state estimation means based on the measured values of the voltage and current of the input unit to which high-frequency AC power is input to the power transmission coil;
Further comprising a combined region discriminating means for obtaining
The non-contact power feeding apparatus according to claim 5, wherein the coupling region determination unit outputs an average value of the coupling state estimation value A and the coupling state estimation value B.

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