JP6530547B1 - Non-contact power supply system when moving - Google Patents

Abstract

An object of the present invention is to achieve quick calculation of matching amount and high-precision impedance matching in real time while maintaining high transmission efficiency and circuit protection on the power transmission element side according to the storage state of a power receiving object while traveling a moving object. It is an object of the present invention to provide a non-contact power feeding system during traveling of a movable body that can SOLUTION: Only an amplitude component is specified from a first reflection coefficient and a second reflection coefficient obtained by opening and closing a connection between an element capable of changing a load impedance on a load side and a power receiving element of a power receiving side device. The load impedance is calculated by the quadratic equation generated from the calculation equation of. And the reactance amount of the variable reactance element necessary for matching the target impedance for matching with the output impedance is calculated from the calculated load impedance. The impedance of the variable reactance element is adjusted, and the duty ratio is controlled by the PWM control circuit according to the storage state of the power receiving object to adjust the increase or decrease of the amount of supplied power. [Selected figure] Figure 1

Description

  TECHNICAL FIELD The present invention relates to a non-contact power feeding system during traveling of a moving body, which is capable of supplying power to a battery or the like when the moving body travels.

  In recent years, for the purpose of improving convenience of power transmission for charging and the like, a power transmission device having a power transmission element for outputting power in a noncontact manner, and power received from the power transmission device in a noncontact manner A non-contact power feeding system including a power receiving side device having a power receiving element of

  In the non-contact power feeding, in order to perform the power transmission with the maximum transmission efficiency without loss of power, it is necessary to match the output impedance of the power transmission device with the load impedance of the power reception device. In particular, in the case of a high frequency circuit, reflection occurs due to a mismatch between the output impedance and the load impedance, that is, both impedances, and it is necessary to match the both impedances in order to reduce the transmission efficiency.

  For example, the impedance matching circuit is composed of a circuit composed of lumped constants L and C or a distributed constant microstrip, and a circuit composed of lumped constants L and C is connected between the antenna and the amplifier circuit ing. Thereby, while suppressing the reflected power loss returned to the power transmission side, it is helping to improve the power transmission efficiency of the entire system (for example, see Patent Document 1).

  Also, an impedance matching circuit is described as a π matching circuit, and it is connected between a drive source having a high frequency signal source and a load, and a method of automatically matching the impedance by application of a power supply voltage from a power supply is available. (See, for example, Patent Document 2).

  In this matching circuit, based on the signals of the traveling wave component detected by the directional coupler and the signals of the reflected wave component, the phase detection circuit compares the phase difference of the signals of the reflected wave component with reference to the signal of the traveling wave component. To detect. The phase difference is determined by the correction direction determination circuit whether or not there is a lead or delay component of a predetermined angle. The variable capacity control circuit increases or decreases the variable capacity of the capacitor based on the determination result to match the output impedance of the drive source with the impedance of the load on the output terminal side.

  In other contactless power transmission systems, a matching circuit is provided, and a detection unit detects an AC signal input to the power transmission resonator. Based on the variation of the AC signal detected by the detection unit, the impedance control unit matches the impedance of the power transmission resonator with the output impedance of the power supply (see, for example, Patent Document 3).

  Furthermore, according to another wireless power transmission system, the matching circuit having the variable reactance element, the traveling wave / reflected wave extraction unit extracting the traveling wave voltage and the reflected wave voltage, and the traveling wave / reflected wave extraction unit A reflection coefficient calculation unit that calculates the reflection coefficient from the traveling wave voltage and the reflection wave voltage, and calculates the input impedance from the relationship between the reflection coefficient, the impedance of the matching target, and the input impedance; A position determination unit and a control value output unit configured to calculate a capacitance value distributed to the variable reactance element of the matching circuit and set the reactance value of the reactance element, and a reflection coefficient absolute value is higher than a predetermined threshold value If it is large, change the row used in the matching correction amount table to change the configuration of the matching circuit. A wireless power transmission system in an electric automatic traveling mode in which the load is supplied with power from the power source at the time of electromagnetic field coupling by the power transmission antenna and the power reception antenna via the configuration for automatically matching the impedance. (See, for example, Patent Document 4).

  An AC power supply having an external power conversion unit for converting external power into DC power of a predetermined voltage value, a DC / AC conversion unit for converting the DC power into AC power of a predetermined frequency, and the AC And a control unit for controlling the AC power supply including variable control of the output power value of the AC power supply, and the primary coil, the secondary coil and the load. In a power transmitting device capable of transmitting AC power without contact to the secondary side coil of a power receiving device having a half bridge circuit, the DC / AC conversion unit includes two switching elements connected in series with each other And the operation mode of the DC / AC conversion unit is a full bridge mode in which both of the two half bridge circuits operate and the two half bridge circuits. The control unit variably controls the ON / OFF duty ratio of both switching elements of the half bridge circuit to be operated among the two half bridge circuits. By doing so, a contactless power transmission apparatus is variably controlled to control the output power value of the AC power supply (see, for example, Patent Document 5).

JP, 2015-56760, A JP, 2010-87845, A JP 2012-135117 A JP, 2015-122955, A JP, 2016-92959, A

  However, as for Patent Documents 1 to 3, it is necessary to prepare several matching circuits in advance and switch the optimum circuit by the switching circuit. It may take time to combine the best matching circuit using voltage feedback and the best algorithm. The load impedance to be matched is to be performed in an unknown state, which causes the circuit to be enlarged and may fail to secure the optimum algorithm. Since the transmission impedance and the reception impedance are not measured accurately, the matching accuracy and the adjustment range may be limited, and impedance matching may not be achieved.

  Further, with regard to Patent Document 4, when changing the configuration of the matching circuit, it is necessary to read out data corresponding to the amount of change from a predetermined matching correction amount table, which takes time for processing throughput. there were. In particular, in an environment where processing in a short time is required, such as when power transfer is performed while moving a moving object, the time required for such processing is an important issue. In particular, although the correction amount necessary for matching differs depending on the load of the power receiving side device, since the value of the predetermined matching correction amount table is a list of discrete values, the corresponding correction amount exists. If not, there was also a risk of falling into a so-called infinite loop.

  By the way, since impedance is a parameter for an AC signal, it is the quotient of signal voltage and current, and has two components of amplitude and phase. That is, it is a complex number. And, in the estimation of the load impedance necessary for impedance matching, any of the above-mentioned prior arts are based on the measurement of the reflection coefficient of a complex number, so the phase synchronization of the reflection coefficient and the influence of the cable length etc. There is a problem that estimation error is likely to occur at the point where the reliability to the accuracy of the impedance matching is low.

  In Patent Document 5, according to the charge state of the battery, the duty ratio of DC / AC conversion is variably controlled, and the amount of supplied power is adjusted so that the output power value becomes the target power corresponding to the change in the impedance of the power supply load. A value of AC power can be output. However, especially when power is supplied to the moving object when the moving object is traveling, the duty disclosed in Patent Document 5 is in spite of the high necessity of the impedance matching because the load is different for each moving object. In the configuration in which the ratio is variably controlled to adjust the feed amount, it is not clear how to adjust the feed amount in conjunction with the impedance matching.

  By the way, when non-contact power feeding is performed while the moving body is traveling, power feeding processing is required in a short time as compared to power feeding in the stationary state of the moving body. There is a possibility that the circuit which constitutes a power transmission element may be damaged.

  The present invention is intended to solve the above-mentioned problems, and while the moving object is traveling, it can be rapidly performed in real time while maintaining high transmission efficiency and circuit protection on the power transmission element side according to the storage state of the power receiving object. An object of the present invention is to provide a non-contact power feeding system during traveling of a mobile body capable of achieving calculation of matching amount and impedance matching with high accuracy.

  In order to achieve the above object, according to the first aspect of the present invention, in the non-contact power feeding system during traveling of a moving object, switching of the connection between the change element capable of changing the load impedance on the load side and the secondary coil of the power receiving side device Only the amplitude component is specified from the obtained first reflection coefficient and second reflection coefficient, the load impedance is accurately calculated by the equation generated from the calculation formula of the two amplitude components, and the target impedance is calculated from the calculated load impedance. The reactance amount of the variable reactance element necessary for matching is calculated, the impedance of the variable reactance element is adjusted, and the duty ratio is controlled by the PWM control circuit according to the storage state of the object to be received, The most important feature is to adjust the

That is, a power transmission side apparatus provided in a track on which the mobile unit travels and including at least a power transmission source and a power transmission element, and the power receiving object attached to the mobile unit and constituting at least a load and the power transmission element And a power receiving device including a power receiving element disposed opposite to each other, and when the movable body travels, power is supplied from the power transmission source to the power transmitting element, and the power transmitting element and the power receiving element encounter each other In the non-contact power feeding system at the time of traveling of a mobile body, power is transmitted from the power transmitting element to the power receiving element to feed power to the power receiving target,
An impedance change unit that changes the load impedance on the load side by a change element having a predetermined change amount;
An opening / closing unit that opens / closes the connection between the impedance changing unit and the power receiving element;
An opening / closing control unit that controls the opening / closing of the opening / closing unit;
A detection unit that detects a voltage of a traveling wave from the transmission power source and a voltage of a reflected wave from the load at both times of the opening and closing;
The impedance changing unit calculates a first reflection coefficient from the detected traveling wave and the reflected wave when the connection with the power receiving element is opened by the opening / closing unit, and identifies only an amplitude component. When the connection with the power receiving element is closed by the open / close unit, the second reflection coefficient is calculated from the detected traveling wave and the reflected wave to specify only the amplitude component, and the calculation of the two amplitude components. A calculation unit that calculates the load impedance according to a quadratic equation generated from an equation;
A matching unit having a variable reactance element to match a target impedance for matching the output impedance with the calculated load impedance;
An impedance adjustment unit which calculates the reactance amount of the variable reactance element necessary for the matching from the calculated load impedance, and adjusts the impedance of the variable reactance element based on the calculated reactance amount;
A power transmission side buffer unit which is always charged when energized by the power transmission source;
A first detection unit provided in the power transmission side device for detecting the storage state of the power reception target, and a PWM control circuit connected to the power transmission element and according to the storage state detected by the first detection unit, A first adjustment unit that controls the duty ratio to adjust the increase or decrease of the amount of supplied power;
Have
When the power transmission element and the power reception element encounter when the movable body travels,
The power from the power transmission source and the power from the power transmission side buffer unit are transmitted by the power impedance having the duty ratio with the output impedance matched by the matching unit, and the power receiving object of the power receiving unit is supplied with power. It is characterized by

  According to this configuration, it is possible to obtain two different reflection coefficients by providing an element for changing the load impedance on the load side, and controlling the connection with the power receiving element. The load impedance is estimated only by the quadratic equation excluding the phase component of the reflection coefficient, that is, only the scalar quantity, the reactance amount necessary for matching the target impedance is calculated, and the output impedance based on the calculation result is The power waveform having the duty ratio enables power transmission.

  Further, in order to achieve the above object, the non-contact power feeding system when traveling a moving object according to the second invention detects voltages at two different points on the transmission line, and generates from the magnitudes of the voltages at the two points. The load impedance is calculated by the simultaneous simultaneous equations, the reactance amount of the variable reactance element necessary to match the target impedance is calculated from the calculated load impedance, the impedance of the variable reactance element is adjusted, The most important feature is that the PWM control circuit controls the duty ratio to adjust the increase or decrease of the amount of supplied power according to the charge state of the above.

That is, a power transmission side apparatus provided in a track on which the mobile unit travels and including at least a power transmission source and a power transmission element, and the power receiving object attached to the mobile unit and constituting at least a load and the power transmission element And a power receiving device including a power receiving element disposed opposite to each other, and when the movable body travels, power is supplied from the power transmission source to the power transmitting element, and the power transmitting element and the power receiving element encounter each other In the non-contact power feeding system at the time of traveling of a mobile body, power is transmitted from the power transmitting element to the power receiving element to feed power to the power receiving target,
A detection unit that detects voltages at two different points on a transmission line having a predetermined length as a first detection voltage and a second detection voltage;
A calculation unit for calculating an estimated value of the load impedance by simultaneous equations generated from the first detection voltage and the second detection voltage;
A matching unit having a variable reactance element to match a target impedance for matching the output impedance with the calculated load impedance;
An impedance adjustment unit which calculates the reactance amount of the variable reactance element necessary for the matching from the calculated load impedance, and adjusts the impedance of the variable reactance element based on the calculated reactance amount;
A power transmission side buffer unit which is always charged when energized by the power transmission source;
A first detection unit provided in the power transmission side device for detecting a storage state of the power reception target;
A first adjustment unit connected to the power transmission element and controlling a duty ratio by a PWM control circuit according to the storage state detected by the first detection unit to adjust an increase or decrease in the amount of supplied power;
Have
When the power transmission element and the power reception element encounter when the movable body travels,
The power from the power transmission source and the power from the power transmission side buffer unit are transmitted by the power impedance having the duty ratio with the output impedance matched by the matching unit, and the power receiving object of the power receiving unit is supplied with power. It is characterized by

  According to this configuration, the first detection voltage and the second detection voltage are obtained from two different points on the transmission line, the load impedance is calculated by simultaneous equations, and the reactance amount necessary for matching the target impedance is calculated. With the output impedance based on the calculation result, it becomes possible to transmit power by the power waveform having the duty ratio.

  In the first invention and the second invention, a plurality of the power transmission elements are installed on the track, and the plurality of power reception elements are mutually connected with a second detection unit that detects the proximity of the movable body. From the position where the movable body is disposed opposite to the power transmitting element and the power receiving element, the power transmitting element side adjacent in the traveling direction And the switching unit switches the power transmission element to be energized to the adjacent power transmission element by the operation of the switching element when the proximity of the moving body is detected by the second detection unit of the adjacent power transmission element; The PWM control circuit may be configured to have a second adjustment unit that adjusts the duty ratio to gradually increase from a low ratio with switching to the adjacent power transmission element.

  According to this configuration, it is possible to alleviate the sharp rise of the voltage at the time of the feeding.

  According to the present invention, in the non-contact power feeding system during traveling of a moving object, the calculation of the load impedance necessary for impedance matching and the specification of the matching amount by the calculated load impedance do not need to be defined and read out in a data table in advance Therefore, the processing speed of impedance matching is dramatically improved, and rapid power transmission and power feeding can be realized.

  It should be noted that since the above equation eliminates the phase component and generates only the amplitude component, the calculation accuracy of the load impedance is dramatically improved, and efficient and highly effective power transmission and feeding can be realized. Play an effect.

  Further, since the PWM control circuit can control the duty ratio to adjust the increase or decrease of the amount of supplied power, the amount of supplied power can be adjusted according to the storage state of the power receiving object, and the efficient supply state can be maintained. The effect of being able to

  Furthermore, when a plurality of the power transmission elements are laid on the track, when the power transmission elements to be energized are switched to the adjacent power transmission elements as the moving body moves, the PWM control circuit causes the duty ratio to gradually increase from a low ratio. Since the adjustment can be performed, it is possible to alleviate the steep rise of the voltage and to protect the circuit constituting the power transmission element.

FIG. 1 is a block diagram of a non-contact power feeding system during traveling of a mobile according to the present invention. FIG. 2 is a view showing a moving body including a power receiving side device and a power transmission side device provided in a track, wherein (a) is a side view showing a correspondence between the moving body and the power transmission side device; (B) is a top view of the power transmission side apparatus arrange | positioned in a track | orbit. FIG. 3 is a block diagram of the impedance matching circuit according to the first embodiment. FIG. 4 is a block diagram of the impedance matching circuit according to the second embodiment. FIG. 5 is a diagram showing the concept of the voltage measurement position on the transmission line in the impedance matching circuit according to the second embodiment. FIG. 6 is a graph showing the nature of a square wave, where (a) is a graph comparing the received power of a sine wave and a square wave, and (b) shows the change in received power when the duty ratio is changed. It is a graph shown. FIG. 7 is a block diagram of the first adjustment unit, where (a) is a block diagram showing the connection form of the oscillation circuit and the first adjustment unit of the noncontact power feeding system during traveling of the mobile body, and (b) is It is a block diagram which shows the structure of PWM control of a 1st adjustment part. FIG. 8 is a block diagram of the second adjustment unit, where (a) is a block diagram showing the connection form of the oscillation circuit and the second adjustment unit of the noncontact power feeding system during traveling of the mobile body, and (b) is It is a block diagram which shows the structure of PWM control of a 2nd adjustment part.

  Hereinafter, in the present embodiment, a system including a primary coil as a power transmitting element and a secondary coil as a power receiving element will be described as an example, but the system according to the present invention is magnetic coupling, electric coupling, and radiation type. It is applicable whether it is any of a feed system, and the shape of a power transmission element and a power receiving element is not limited to a coil, either.

  With reference to FIG. 1, 1 demonstrates the non-contact electric power feeding system at the time of the moving body traveling | moving concerning this invention. The present embodiment exemplarily shows an embodiment of a non-contact power feeding system at the time of traveling of a moving object, and the present invention is not intended to be limited to this embodiment.

  The noncontact power feeding system 1 includes a charging circuit unit 2, a power transmission unit 3, a power transmission head unit 4, a power receiving head unit 5, and a power receiving unit 6. The charging circuit unit 2, the power transmission unit 3 and the power transmission head unit 4 constitute a power transmission side device A, and the power reception head portion 5 and the power reception unit 6 constitute a power reception side device B. The power transmission side device A and the power reception side device B are separately provided separately from each other.

  The charging circuit unit 2 of the power transmission side device A has a power transmission side capacitor 9 charged via the power transmission side rectification circuit 8 by a power source 7 (power transmission power source) having a standard voltage of AC 100/200 V at a frequency of 50 Hz or 60 Hz, for example. It is provided as a power transmission side buffer unit. The power transmission side capacitor 9 is connected so as to receive power supply from the power supply 7 and is always charged when the power supply 7 is energized. The power transmission side capacitor 9 is connected to the power supply circuit 12 that constitutes the power transmission unit 3. The term "power supply" is used synonymously with "charge" in the following description.

  The power transmission unit 3 includes a power supply circuit 12 connected to the power supply 7. The power supply circuit 12 is provided with a charge control unit 10 as a charge control circuit, and an oscillation circuit 13 and a drive circuit 14 that constitute an inverter circuit. The power supply circuit 12 is provided with a power transmission side control circuit unit 16 to which the pilot lamp 15 is connected. The power transmission side control circuit unit 16 lights the pilot lamp 15 when it receives a power supply signal S1 from the communication circuit 17 described later.

  The power transmission head unit 4 includes a communication circuit 17 and a primary coil 18, and the communication circuit 17 uses a control signal S1 as a communication medium (radio wave, light, sound wave, ultraviolet light, infrared light or thermal wave) from a communication control unit 20 described later. It is supposed to receive The primary coil 18 is connected to receive the current from the drive circuit 14 to generate a magnetic field.

  The power receiving head unit 5 of the power receiving device B includes a power receiving rectifier circuit 19 and a communication control unit 20. The power reception side rectification circuit 19 has a secondary coil 19a that receives power transmission from the primary coil 18 through the impedance matching circuit 100 by electromagnetic field coupling in the electromagnetic field coupling unit. The communication control unit 20 has a transmitting unit (not shown) for transmitting the control signal S1 to the communication circuit 17. The impedance matching circuit 100 is provided to automatically match the impedance between the power supply and the circuit side of the primary coil 18 by a mechanism described later. The coil of the impedance matching circuit 100, the primary coil 18, and the secondary coil 19a are all formed of litz wire to increase the Q factor (Quality Factor).

  The power reception unit 6 includes a control detection circuit 22 and a power reception control circuit unit 23, and sends the current from the power reception rectification circuit 19 to the control detection circuit 22. The power receiving side control circuit unit 23 is connected to send the detection signal S3 from the control detection circuit 22 to the communication control unit 20. The control detection circuit 22 is connected to the power receiving capacitor 24 as a power receiving object. Power reception side capacitor 24 constitutes power storage unit 11 and is charged by combined power.

  The impedance matching circuit 100 is provided between the power transmission source 7 and the primary coil 18. The impedance matching circuit 100 may be provided between the secondary coil 19a and the load side.

  FIG. 2 is a view showing a mobile body (vehicle) including the power receiving side device B and a power transmission side device A provided in the track. The power transmission side device A is embedded in a track 100A (for example, in a paved road) on the ground where the moving body 25 travels, and the power receiving side device B is attached to the moving body 25. During traveling of the moving body 25 such as a vehicle, as described above, at the time of energization from the power source 7 (not shown in FIG. 2) to the primary coil, from the circuit side of the primary coil 18 at the encounter with the secondary coil 19a Power is transmitted from the circuit side of the primary coil 18 to the circuit side of the secondary coil 19a to supply power to the power reception target.

  In the present embodiment, the primary coil 18 of the power transmission side device embedded in the track 100A is a horizontally-ellipse oval from an arc-shaped portion connecting two linear portions arranged in parallel and both ends of the linear portion. A plurality of primary coils 18 are arranged at predetermined intervals along the traveling direction Rm of the track 100A. However, the primary coil 18 is not the meaning limited to the said elliptical shape. Therefore, any shape may be used as long as the above function is exhibited, such as a perfect circular shape, a rectangular shape, an engagement shape of concavities and convexities, a polygonal shape, and a meander shape.

  In order to prevent magnetic diffusion between the primary coil 18 and the secondary coil 19a below the primary coil 18 of the power transmission side device on the track 100A, it is made of a hard magnetic material such as ferrite in order to improve the coupling coefficient. A collecting plate (not shown) is placed in close equilibrium with the primary coil 18.

  Since the primary coils 18 are horizontally oblong, by laying a large number of primary coils 18 horizontally at predetermined intervals along the traveling direction Rm of the track 100A, a laying distance per single primary coil 18 is secured. And can be placed over long distances with a small number of primary coils 18. In this case, since the impedance matching circuit 100 having a coil is located within the range of the primary coil 18, the magnetic flux of the impedance matching circuit 100 with respect to the primary coil 18 can be efficiently sent without leaking to the outside.

  Adjacent primary coils 18 are connected by a wire (corresponding to a connecting portion) via a switching element 100B (corresponding to a switching portion). The separation dimension of the adjacent primary coils 18, that is, the separation distance between the front end of one primary coil 18 and the rear end of the other primary coil 18 is, for example, an oval of the primary coil 18 along the traveling direction of the moving body 25. Set to 1/2 to 2 times the dimension. However, the separation distance can be set as desired according to the arrangement of the primary coil 18, the installation of the track 100A, the use environment, and the like.

  When the moving body 25 travels, when the primary coil 18 and the secondary coil 19a encounter each other, the second detection sensor 100C (corresponding to a second detection unit) detects the encounter between the two, thereby activating the switching element 100B. The primary coil 18 adjacent to the traveling direction Rm in the trajectory 100A is set to switch from one to the other.

  In this manner, as the moving body 25 moves in the traveling direction Rm during traveling, the secondary coil 19a is continuously resonated whenever the secondary coil 19a sequentially encounters a large number of adjacent primary coils 18 As a result, continuous power feeding can be performed when the moving body 25 travels.

  Specifically, the power receiving side device B including the impedance matching circuit 100 and the secondary coil 19 a is attached to the back surface side of the vehicle body 25 a of the movable body 25 via the attachment plate.

  The power receiving side capacitor 24, which is a power receiving object, is connected to, for example, a battery cell 24A for charging disposed in a hood of a car, and is used as a driving motor or various electric components It is designed to be used for operation etc.).

  Although FIG. 2 shows a state in which one mobile unit 25 travels on the track 100A, the power transmission side device A encounters the plurality of mobile units 25 traveling on the track 100A. It is also possible to simultaneously supply power by PWM control described later via each primary coil 18.

First Embodiment of Impedance Matching Circuit
FIG. 3 is a block diagram of the impedance matching circuit 100 described in FIG. The impedance matching circuit 100 is a circuit provided to perform impedance matching in power transmission between the output impedance of the power supply side (transmission power source) and the load impedance of the power reception side (load), as described later. If the output impedance on the feed side and the load impedance on the power receive side do not match, the reflected wave generated by the power that can not be consumed on the power receive side interferes with the incident wave on the feed side, generating a standing wave. . And the loss of the electric power which generate | occur | produces by such a standing wave arises.

In the impedance matching circuit 100, a matching impedance (that is, a target impedance) is determined by the matching unit 107 with respect to the load impedance Z _L of the power receiving object as a load, as described later.

  An impedance change unit 101 is connected between the load and the matching unit 107. In this embodiment, the load is connected in parallel to the load, but may be connected in series. The impedance changing unit 101 may be connected to the impedance matching circuit 100 to connect an element that changes the load impedance, and may be, for example, a capacitor or a coil. The impedance of the element itself connected to the impedance changing unit 101 is known.

  The impedance changing unit 101 changes the load impedance by opening and closing the opening and closing unit 102. For example, the switching unit 102 may switch the connection with the secondary coil 19a (impedance matching circuit 100) by a switch. The opening and closing of the opening and closing unit 102 is controlled by an opening and closing control unit 103 which performs microcomputer control of the opening and closing of the switch according to a predetermined condition. The predetermined condition is, for example, that the open / close unit 102 is in an initial state and is in an open state (off state) with respect to the impedance change unit 101, and the data in the initial state is acquired by the signal processing unit 105 described later. The change unit 101 may be closed (on).

  The detection unit 104 detects the voltage of the incident wave from the power supply side and the voltage of the reflected wave from the load side in real time. That is, the incident wave voltage vi is detected by the first detection unit 104a, and the reflected wave voltage vr is detected by the second detection unit 104b. The reflection coefficient is obtained from the ratio of the reflected wave voltage vr to the incident wave voltage vi. Accordingly, the detection unit 104 detects two reflection coefficients when the impedance change unit 101 is not present and when the impedance change unit 101 is not present when the opening and closing part 102 is opened and closed.

The input wave voltage vi and the reflected wave voltage vr detected by the detection unit 104 are subjected to analog-to-digital conversion processing by the AD conversion unit 105a of the signal processing unit 105, and calculation for load impedance estimation is performed by the calculation unit 105b. Run. Here, assuming that the reflection coefficient when the impedance changing unit 101 is off is Γ ₁ , the load impedance is Z _L , and the target impedance Z ₀ , the following equation is established.

On the other hand, when the impedance change unit 101 is on, the reflection coefficient is Γ2, the load impedance is Z _L2 , the target impedance Z ₀ , and the amount of change in impedance when the impedance change unit 101 is on is jΔX, the load Assuming that the real part of the impedance Z _L is R and the imaginary part is jX, the following equation holds.

但し、

However,

The reflection coefficients Γ ₁ and Γ ₂ are all values including the amplitude value and the phase angle, but the reflection coefficients Γ ₁ and Γ ₂ become complex numbers by including the phase angle. Then, due to the difficulty of the phase estimation, the accuracy of the estimation of the load impedance Z _L may be lowered. Therefore, in order to extract only the magnitude of the reflection coefficient, the calculation unit 105b calculates absolute values | Γ ₁ |, | Γ ₂ |. Moreover, the impedance of the said element which comprises the impedance change part 101 is a known value. Therefore, with the configuration of the impedance matching circuit 100 including the impedance changing unit 101, the calculating unit 105b can derive a quadratic equation of the real part R from Equation 1 and Equation 2 as shown below by Equation 3. The constants a, b, c and p, q in the following equation 3 can be obtained from the calculated absolute values | Γ ₁ |, | Γ ₂ | and the amount of change in the impedance from jΔX.

Since the load impedance and the reflection coefficient are in a one-to-one correspondence relationship, the load impedance Z _L can be derived from the reflection coefficient by providing the impedance changing unit 101 and performing on / off control, as described above. Simple calculation is possible.

Next, when the estimated value of the load impedance Z _L is calculated by the calculation unit 105 b, an element of the matching circuit that matches the target impedance Z ₀ can be determined.

  The calculated matching amount is first converted by the D / A converter 106 a into an analog signal by the impedance adjuster 106. From there, each capacitance value of each variable capacitor Cx, Cy, Cz of T type, L type or pi type circuit is calculated.

  The impedance adjustment unit 106 sets a control voltage value according to the matching amount, and based on the control voltage value corresponding to each of the capacitance values, the first drive unit 106 b, the second drive unit 106 c, and the third drive unit 106 d The first motor 106e, the second motor 106f, and the third motor 106g connected to the variable capacitors Cx, Cy, Cz of the matching unit 107 are energized to perform impedance matching processing.

  With the above configuration, impedance matching can be performed by simple calculation processing. For example, a data table indicating the relationship between the reflection coefficient and the control value as described above is set in advance, and each time the impedance matching processing is performed, Processing such as reading the data table becomes unnecessary. Further, by providing the impedance changing unit 101 and intentionally calculating two different load impedances, it becomes possible to eliminate the phase angle that lowers the calculation accuracy, and the complicated processing of reading the data table As a result, the calculation processing accuracy for performing impedance matching is improved, and the throughput is also improved.

Second Embodiment of Impedance Matching Circuit
FIG. 4 is a block diagram of the impedance matching circuit 200 according to the second embodiment. Similarly to the impedance matching circuit 100 according to the first embodiment, even if the impedance matching circuit 200 is provided between the power transmission source 7 and the circuit side of the primary coil 18, it is between the power receiving load side and the circuit side of the secondary coil 19a. It may be provided in Similar to the impedance matching circuit 100 according to the first embodiment, the impedance matching circuit 200 also performs impedance matching by a simple calculation process. The load impedance has a transmission line having a predetermined length, and is calculated from voltages at two different points on the transmission line. That is, in the case of a high frequency, on a transmission line such as a long coaxial cable or parallel wire, the voltage is constant at any position unless there is a reflected wave, but the power transmission side and the power reception side fail. Because of the matching, when a reflected wave is generated, the presence of the standing wave causes a mismatch in voltage amplitude values at two different points on the transmission line as a distributed constant circuit. The present embodiment utilizes this property.

The impedance matching circuit 200 determines the matching impedance (that is, the target impedance) by the matching unit 204 with respect to the load impedance Z _L of the power receiving object to be a load, as described later.

As shown in FIG. 3, the detection unit 201 detects voltages at two arbitrary different points on the transmission line W, ie, a point at a distance of X ₁ from the load and a point at a distance of X ₂ from the load. Do. The first voltage detecting unit 201a detects a voltage of a point at a distance of X _1, the second voltage detecting unit 201b are respectively detected in real time the voltage of the point at a distance of X2.

The voltage at the two points detected by the detection unit 201 is subjected to analog-to-digital conversion processing by the AD conversion unit 202a of the signal processing unit 202, and then the calculation unit 202b executes calculation for estimation of the load impedance. Here, the voltage detected at X ₁ is V ₁ , the voltage detected at X ₂ is V ₂ , the incident wave voltage is V _i , the reflection coefficient of the transmission line is Γ _L , the phase constant is β, and the load L to X ^Assuming that the reflection coefficient of a point separated by ₁ is Γ _L ^−2βX _{1 and} the reflection coefficient of a point separated by X ₂ from the load L is Γ _L ^−2βX 2, the following two equations hold.

Then, the incident wave voltage V _i is known, and from the general expression of the phase constant β, two expressions of Expression 4 hold as simultaneous equations for estimating the reflection coefficient Γ _L of the transmission line. By the way, assuming that the load impedance Z _L and the target impedance Z ₀ , the following equation holds. That is, the load impedance Z _L can be estimated based on the detection of voltages at two points and the simultaneous equations according to the two equations of Equation 4.

Next, when the estimated value of the load impedance Z _L is calculated by the calculation unit 202 b, a circuit element that matches the target impedance Z ₀ is calculated.

  The calculated matching amount is first converted to an analog signal by the DA conversion unit 203 a by the impedance adjustment unit 203. The converted matching amount is distributed to the respective capacitance values of the variable capacitors Cx, Cy, Cz of the T-type circuit (or L-type, π-type) constituting the matching unit 204. The respective capacitance values can be easily calculated if the total amount of the variable capacitors Cx, Cy, Cz is the matching amount and the voltage value and the current value are known.

  The impedance adjustment unit 203 sets control voltage values according to the matching amount, and the first drive unit 203b, the second drive unit 203c, and the third drive unit 203d are set based on the control voltage values corresponding to the respective capacitance values. The first motor 203e, the second motor 203f, and the third motor 203g connected to the variable capacitors Cx, Cy, Cz of the matching unit 204 are energized to perform impedance matching processing.

With the above configuration, impedance matching can be performed by simple calculation processing. For example, a data table indicating the relationship between the voltage at an arbitrary point and the control value as described above is set in advance, and impedance matching processing is performed. Every time, the processing such as reading the data table becomes unnecessary. That is, since the complicated process of reading the data table can be eliminated, the impedance matching can be executed by the analytical method with a small number of procedures, and the calculation processing accuracy is improved and the throughput is also improved. In this embodiment, the voltage at any two points (X ₁ , X ₂ ) is detected by the estimation of the load impedance Z _L , but three or more points may be detected. .

  Hereinafter, PWM control of the non-contact power feeding system 1 will be described with reference to FIGS. 5 to 7.

  Here, PWM (Pulse Width Modulation) control is one of the power control methods, and in the inverter circuit, the on / off switching of the pulse train on / off time changes the on / off time width. Control to generate a desired sinusoidal AC voltage proportional to the on pulse width, and the duty ratio refers to the ratio of the on time width to one cycle of the square wave.

  As shown in FIG. 5A, in the non-contact power feeding system, the change in received power when the gap between the primary coil and the secondary coil is changed to 0 mm to 15 mm is a sine wave and a square wave (duty ratio 50% There is no big difference between the two), and it can be seen that good non-contact power feeding similar to a sine wave can be performed even with a square wave. Next, as shown in FIG. 5B, it can be seen that with a square wave, with the duty ratio of 50% as the maximum received power, the received power decreases as it deviates from 50% regardless of the magnitude of the duty ratio. However, even if the duty ratio is changed, the transmission efficiency is maintained at about 95%. That is, when non-contact power feeding is performed using a square wave, by changing the duty ratio, it is possible to control increase / decrease of received power while keeping transmission efficiency constant. This is a unique property of square waves that can not be seen with sine waves.

  Therefore, within the range of duty ratio more than 0% and less than 100% (duty ratio is 0%, 100% becomes direct current, and can not transmit power), the duty ratio is increased or decreased according to the demand for power on the load side. It will be possible to adjust the

  Hereinafter, the first adjustment unit 30 will be described with reference to FIG. A current is supplied to the primary coil 18 (not shown in FIG. 6) via the oscillation circuit 13 (inverter circuit), and the oscillation circuit 13 is connected to the first adjustment unit 30. The first adjustment unit 30 is configured of a duty ratio control circuit 13B that controls the duty ratio in order to adjust the amount of supplied power according to the storage state of the power reception target by the PWM control circuit 13A.

  As is well known, the PWM control circuit 13A changes the duty ratio of the pulse width in accordance with the magnitude of the input signal (DC level) at a constant period. The control of the duty ratio produces a PWM output from the microchip 24m to generate a square wave, as shown in FIG. 6 (b). The microchip 24m has one channel of hardware PWM built-in, and the battery cell 24A is a first detection sensor that detects the state of charge such as charge rate (SOC), discharge performance (SOF) or remaining capacity (SOH) 12 n (first detection unit) is connected.

  The clock pulse KC from the CPU clock 12w is sent to the timer 12s via the prescaler 12t. At this time, the output from the first detection sensor 12n is sent to the PR register 12r, and the PWM cycle and the duty ratio are set via the DC register 12q and the timer 12s. The duty ratio (Hi / T) according to the storage state of the battery cell 24A is calculated from the duty ratio related to the set PWM cycle and the PWM cycle T. The primary coil 18 is resonantly excited by the power waveform having this duty ratio.

  Hereinafter, the second adjustment unit 40 will be described with reference to FIG. The second adjustment unit 40 changes the control mode of the first adjustment unit 30 described with reference to FIG. That is, when it is detected that the movable body 25 has come close by the detection of the second detection sensor 100C described in FIG. 2, another primary coil 18 adjacent to one of the plurality of primary coils 18 is operated by the operation of the switching element 100B. When switching to the other primary coil 18, current flows through the oscillation circuit 13 (inverter circuit). At this time, in accordance with the switching by the switching element 100B, the PWM control circuit 13A via the oscillation circuit 13 becomes a control mode for alleviating the steep rise of the voltage whose duty ratio gradually increases from the low ratio (FIG. 7 (b)) reference).

  By adopting the control mode for relaxing the sharp rise of the voltage of the duty ratio control circuit 13B, the duty ratio (pulse width Px) gradually increases from the low ratio. Therefore, among the adjacent primary coils 18, when switching the primary coil 18 by the switching unit by the operation of the switching element 100B, the generation of the induced electromotive force to the other adjacent primary coil 18 is reduced, and the primary coil It contributes to the circuit protection that constitutes 18.

  As described above, in any of the embodiments, the power transmission device A may simultaneously supply power to the plurality of moving bodies 25 traveling on the track 100A through the primary coils 18 that have been encountered. It is possible. At this time, the transmission frequency is fixed at a predetermined basic frequency (for example, 100 kHz, 6.78 kHz) in the adjustment of the duty ratio. That is, when power is supplied to the plurality of moving bodies 25 with different frequencies according to the different storage states, there is a possibility that the power transmission side device A and the power reception side device B may deviate from resonance. There is a disadvantage that power can not be supplied (charged) to the power receiving target. Therefore, by fixing the fundamental frequency in the first adjustment unit 30 or the second adjustment unit 40, the power storage state of each mobile unit 25 is maintained while maintaining the resonance state between the power transmission device A and the power reception device B. According to it, simultaneous feeding becomes possible.

  Further, as described above, the impedance matching according to the first embodiment or the second embodiment is made even if there are a plurality of power receiving objects (mobiles 25) having different load impedances on the load side by fixing the fundamental frequency. The circuit makes it possible to simultaneously supply maximum power in each transmission system. That is, if it is possible to variably adjust the frequency if the power transmitting side device A and the power receiving side device B correspond to each other on a one-to-one basis, it is possible to adjust the frequency variably. In the case of supplying power, if the frequency is changed, the power may not be supplied because it deviates from resonance. In the present invention, since the PMW power control is used to adjust the duty ratio, it is possible to simultaneously perform the maximum power supply to the plurality of moving bodies 25 by the impedance matching circuit. Play.

DESCRIPTION OF SYMBOLS 1 Non-contact power feeding system 12 n 1st detection sensor 13 oscillation circuit 13A PWM control circuit 13B duty ratio control circuit 25 mobile 100, 200 impedance matching circuit 100A track 100A switching element 100C 2nd detection sensor 101 impedance change part
102 opening / closing unit 103 opening / closing control unit 104, 201 detection unit 105, 202 calculation unit 106, 203 impedance adjustment unit 107, 204 matching unit

Claims (7)

A power transmission side device provided in a track on which the mobile unit travels and including at least a power transmission source and a power transmission element, attached to the mobile unit, and facing at least a power receiving object constituting the load and the power transmission element And a power receiving element including the power receiving element disposed, and when the movable body travels, the power is supplied from the power transmission source to the power transmitting element, and the power transmitting element and the power receiving element encounter each other. In a non-contact power feeding system at the time of traveling of a moving body, which performs power transmission from a power transmission element to the power receiving element and feeds power to the power receiving target,
An impedance change unit that changes the load impedance on the load side by a change element having a predetermined change amount;
An opening / closing unit that opens / closes the connection between the impedance changing unit and the power receiving element;
An opening / closing control unit that controls the opening / closing of the opening / closing unit;
A detection unit that detects a voltage of a traveling wave from the transmission power source and a voltage of a reflected wave from the load at both times of the opening and closing;
The impedance changing unit calculates a first reflection coefficient from the detected traveling wave and the reflected wave when the connection with the power receiving element is opened by the opening / closing unit, and identifies only an amplitude component. When the connection with the power receiving element is closed by the open / close unit, the second reflection coefficient is calculated from the detected traveling wave and the reflected wave to specify only the amplitude component, and the calculation of the two amplitude components. A calculation unit for calculating the estimated value of the load impedance by a quadratic equation generated from an equation;
A matching unit having a variable reactance element to match a target impedance for matching the output impedance with the calculated load impedance;
An impedance adjustment unit which calculates the reactance amount of the variable reactance element necessary for the matching from the calculated load impedance, and adjusts the impedance of the variable reactance element based on the calculated reactance amount;
A power transmission side buffer unit which is always charged when energized by the power transmission source;
A first detection unit provided in the power transmission side device for detecting the storage state of the power reception target, and a PWM control circuit connected to the power transmission element and according to the storage state detected by the first detection unit, A first adjustment unit that controls the duty ratio to adjust the increase or decrease of the amount of supplied power;
Have
When the power transmission element and the power reception element encounter when the movable body travels,
The power from the power transmission source and the power from the power transmission side buffer unit are transmitted by the power impedance having the duty ratio with the output impedance matched by the matching unit, and the power receiving object of the power receiving unit is supplied with power. A non-contact power feeding system during traveling of a moving body characterized by A power transmission side device provided in a track on which the mobile unit travels and including at least a power transmission source and a power transmission element, attached to the mobile unit, and facing at least a power receiving object constituting the load and the power transmission element And a power receiving element including the power receiving element disposed, and when the movable body travels, the power is supplied from the power transmission source to the power transmitting element, and the power transmitting element and the power receiving element encounter each other. In a non-contact power feeding system at the time of traveling of a moving body, which performs power transmission from a power transmission element to the power receiving element and feeds power to the power receiving target,
A detection unit that detects voltages at two different points on a transmission line having a predetermined length as a first detection voltage and a second detection voltage;
The estimated value of the load impedance on the load side by a simultaneous equation generated from the first detection voltage and the second detection voltage, the incident wave voltage on the transmission line, the phase constant, and the reflection coefficient of the two points Calculation unit to calculate
A matching unit having a variable reactance element to match a target impedance for matching the output impedance with the calculated load impedance;
An impedance adjustment unit which calculates the reactance amount of the variable reactance element necessary for the matching from the calculated load impedance, and adjusts the impedance of the variable reactance element based on the calculated reactance amount;
A power transmission side buffer unit which is always charged when energized by the power transmission source;
A first detection unit provided in the power transmission side device for detecting the storage state of the power reception target, and a PWM control circuit connected to the power transmission element and according to the storage state detected by the first detection unit, A first adjustment unit that controls the duty ratio to adjust the increase or decrease of the amount of supplied power;
Have
When the power transmission element and the power reception element encounter when the movable body travels,
The power from the power transmission source and the power from the power transmission side buffer unit are transmitted by the power impedance having the duty ratio with the output impedance matched by the matching unit, and the power receiving object of the power receiving unit is supplied with power. A non-contact power feeding system during traveling of a moving body characterized by   The power transmission side buffer unit is at least one of a power transmission side capacitor or a power transmission side battery, and the power reception target is provided as at least a power reception side capacitor or a power reception side battery. The non-contact electric power feeding system at the time of mobile body traveling according to claim 1 or claim 2.   A plurality of power transmission elements of the power transmission side device are disposed on the track at a predetermined interval, and the non-traveling vehicle according to any one of claims 1 to 3 Contact power supply system.   A plurality of the power transmission elements are laid on the track, and each of the plurality of power transmission elements includes a second detection unit that detects the proximity of the mobile object, a connection unit that connects the power transmission elements adjacent to each other, The movable body moves from the position where the power transmission element and the power reception element are disposed facing each other to the power transmission element side adjacent in the traveling direction, and the second detection unit of the adjacent power transmission element When proximity is detected, the switching unit switches the power transmission element to be energized to the adjacent power transmission element by the operation of the switching element interposed in the connection unit, and switching to the adjacent power transmission element by the switching unit, The mobile unit according to any one of claims 1 to 4, further comprising: a second adjustment unit that adjusts the duty ratio to gradually increase from a low ratio by a PWM control circuit. Non-contact power supply system of the time.   6. The power transmission side device according to claim 1, wherein power is simultaneously supplied to the plurality of mobile units traveling on the track through the power transmission elements encountered. The non-contact electric power feeding system at the time of the moving body traveling according to item 1.   A non-contacting state during traveling of a mobile according to any one of claims 1 to 5, wherein the transmission frequency is fixed at a predetermined basic frequency in the adjustment of the duty ratio by the PWM control circuit. Power supply system.

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