JP7246977B2 - Contactless power transmission device, power transmission device, and power receiving device - Google Patents

Description

The present disclosure relates to a contactless power transmission device that transmits power by magnetic field resonance generated between a power transmission coil of a power transmission device on a power transmission side and a power reception coil of a power transmission device on a power reception side, and in particular, bidirectional power transmission. a contactless power transmission device, a power transmission device, and a power reception device.

A magnetic resonance type contactless power transmission device that includes a resonance circuit having a coil and a capacitor, and transmits power in a contactless manner using magnetic coupling generated between a power transmission coil of a power transmission device and a power reception coil of a power reception device. It is widely used as a charging device for on-board batteries of electric vehicles, and as a charger for secondary batteries that serve as operating power sources for various electronic devices, especially portable electronic devices.

In such a contactless power transmission device, the power transmission device on the power transmission side and the power transmission device on the power reception side are determined in advance, and the power transmission direction is limited to one direction. A bidirectional contactless power transmission device capable of bidirectionally contactless power transmission and reception has been proposed.

As such a bidirectional contactless power transmission device, a bidirectional resonance circuit having a switch for switching between series connection and parallel connection of a resonance coil and a capacitor, a power conversion device operating as an inverter and a converter, and a step-up/step-down A proposed device includes a converter and a switch for switching between a power conversion DC power supply and a load circuit, in which a resonance coil and a capacitor are connected in series in a power transmission device, and a resonance coil and a capacitor are connected in parallel in a power reception device. (See Patent Document 1).

Further, the power transmitting device and the power receiving device are provided with a resonance section in which a resonance coil and a capacitor are connected in series, a full-bridge inverter in which FETs are bridge-connected, and a bidirectional DD converter capable of stepping up and down, and , the power supply voltage is lowered to drive the power transmission inverter, and the power receiving device uses the body diode of the FET of the full bridge inverter to form a full bridge detection circuit, boosts the detected voltage and transmits it to the load side. By doing so, it is proposed to lower the detection voltage and improve the efficiency (see Patent Document 2). In the two-way contactless power transmission device described in Patent Document 2, since the power transmission device and the power reception device are provided with a series resonance circuit, a soft start is possible by suppressing the current at the start of power transmission, and the power reception device When an excessive current is flowing in the power receiving device, the output from the power receiving device can be cut off only by the operation of the power receiving device, and at the same time, the output impedance of the inverter of the power transmission device can be increased to reduce the power to be transmitted.

JP 2012-244635 A Japanese Patent No. 6038386

The two-way contactless power transmission device described in Patent Document 1 requires a series resonance circuit in which capacitors are connected in series and a parallel resonance circuit in which capacitors are connected in parallel as two-way resonance circuits. The circuit configuration including this becomes complicated, which leads to an increase in cost and also tends to cause a problem of durability.

On the other hand, in the two-way contactless power transmission device described in Cited Document 2, since the power transmission device and the power reception device are provided with series resonance circuits, it is necessary to perform resonance according to the drive frequency. and C must be set to predetermined values. However, in a contactless power transmission device, the coupling coefficient of both coils can be affected by fluctuations in the distance between the resonance circuit of the power transmission device and the resonance coil of the power reception device, or by the presence of metal foreign matter between the resonance coils of both devices. changes, in order to efficiently transmit power at a high voltage, it is necessary to make the values of L and C of the resonant circuit variable so as to cope with fluctuations in the coupling coefficient. Also, in order to transmit power at high voltage, the power supply system must be a high voltage system, while the control circuit and logic circuit for controlling power transmission and reception are low voltage systems. , the circuit configuration becomes complicated. Therefore, the number of sensors and the like for grasping and controlling the operations of these many systems will increase. Therefore, the cost of the contactless power transmission device as a whole tends to increase.

The present disclosure solves the above-described conventional problems, and provides a power transmission device that can cope with changes in the coupling coefficient between the resonance coil of the power transmission device and the resonance coil of the power reception device, and that can be realized at low cost. An object of the present invention is to obtain a contactless power transmission device that can be used as both a power receiving device and a power receiving device. Another object of the present invention is to obtain a power transmitting device and a power receiving device that take advantage of the features of this contactless power transmission device.

In order to solve the above problems, a contactless power transmission device disclosed in the present application is capable of contactless bidirectional power transmission, and includes a chargeable and dischargeable power source, a switching circuit composed of a plurality of switching elements, and a coil. and a capacitor, and a drive control circuit for controlling the ON/OFF operation of each switching element constituting the switching circuit, the power transmission device being used both as a power transmission device and as a power reception device. Alternatively, in any power receiving device, the excessive voltage of the resonance voltage of the coil, the excessive current of the resonance current of the coil, the temperature in the power transmission device, the excessive current during power supply to the power supply, the above At least one predetermined condition of the group consisting of overvoltage of the power supply is detected, and based on the detection result of the predetermined condition, the drive control circuit is either the power supply side or the ground side of each switching element that constitutes the switching circuit. is characterized in that control is performed to turn on only the switching element of

In the contactless power transmission device disclosed in the present application, a predetermined condition is detected, and based on the detection result of the predetermined condition, the drive control circuit performs switching of either the power supply side or the ground side of each switching element that constitutes the switching circuit. Control is performed to turn ON only the element.
A predetermined condition occurs when the operation of power transmission or power reception is excessive, and if this state is left as it is, trouble such as damage occurs in the power transmission or power reception device. Therefore, the operation of this means works as an operation to prevent damage, etc., and it is possible to provide a safe non-contact power transmission device that can function as both a power transmitting device and a power receiving device.

It is a block diagram explaining schematic structure of the power transmission apparatus and power receiving apparatus using the contactless electric power apparatus concerning this embodiment. It is a circuit block diagram explaining the composition of the non-contact electric power transmission equipment concerning this embodiment. It is an image figure explaining the state which is performing electric power transmission using the non-contact electric power transmission apparatus concerning this embodiment. It is a figure explaining operation|movement of the state using the contactless power transmission apparatus concerning this embodiment as a power transmission apparatus. 7 is a timing chart for explaining step response at startup and operation for increasing resonance in a resonance system when the contactless power transmission device according to the present embodiment is used as a power transmission device; 4 is a timing chart explaining that resonance current can be detected regardless of PWM control operation and PWM control operation when the contactless power transmission device according to the present embodiment is used as a power transmission device. FIG. 10 is a diagram illustrating an operation state such as resonance current detection in a power transmission suspension (interruption) mode when the contactless power transmission device according to the present embodiment is used as a power transmission device; 5 is a timing chart for explaining operations such as resonance current detection in a power transmission suspension (interruption) mode when the contactless power transmission device according to the present embodiment is used as a power transmission device; 5A and 5B are timing charts for explaining operations such as resonance current detection in a power transmission mode, a rest (shutdown) mode, and a power reception mode when the contactless power transmission device according to the present embodiment is used as a power transmission device; It is a figure explaining operation|movement of the state using the contactless power transmission apparatus concerning this embodiment as a power receiving apparatus. 5 is a timing chart for explaining operations such as synchronous rectification operation and resonance current detection when the contactless power transmission device according to the present embodiment is used as a power receiving device; FIG. 4 is a diagram for explaining an operation state in a power receiving pause (shutdown) mode when the contactless power transmission device according to the embodiment is used as a power receiving device; 5 is a timing chart for explaining operations such as resonance current detection in a power reception pause (shutdown) mode when the contactless power transmission device according to the present embodiment is used as a power receiving device; 4 is a timing chart for explaining operations such as resonance current detection in a power reception mode, a rest (shutdown) mode, and a power transmission mode when the contactless power transmission device according to the present embodiment is used as a power receiving device; FIG. 3 is an image diagram for explaining an example of bidirectional power transmission using the contactless power transmission device according to the present embodiment as a power transmission device and a power reception device;

A contactless power transmission device of the present invention is a power transmission device capable of contactless two-way power transmission, and is a power transmission device capable of contactless two-way power transmission. a switching circuit comprising a plurality of switching elements, a resonance system comprising a coil and a capacitor, and a drive control circuit for controlling the ON/OFF operation of each switching element constituting the switching circuit, The power transmission device is used as both a power transmission device and a power reception device, and the excessive voltage of the resonance voltage of the coil, the excessive current of the resonance current of the coil, the -temperature in the power transmission device, and the power supply at the time of power supply to the power supply. At least one predetermined condition selected from the group consisting of excessive current and excessive voltage of the power supply is detected, and based on the detection result of the predetermined condition, the drive control circuit controls the power supply side or ground of each switching element constituting the switching circuit. control is performed to turn on only one of the switching elements on the side.

EMBODIMENT OF THE INVENTION Hereinafter, embodiment about the non-contact electric power transmission apparatus concerning this indication is described concretely, referring drawings.

In the contactless power transmission device according to the present embodiment described below, one power transmission device functions both as a power transmission device on the power transmission side and as a power reception device on the power reception side to perform bidirectional power transmission. can be done. In the following description, the power transmitting device that transmits power and the power receiving device that receives power will be described separately.

(Embodiment)
1 and 2 are block diagrams for explaining the schematic configuration of the contactless power transmission device according to this embodiment. FIG. 1 is a diagram showing a state in which the contactless power transmission device according to the present embodiment is used as a power transmission device and a power reception device, respectively, and is transmitting and receiving power. On the other hand, FIG. 2 is a diagram illustrating in more detail the configuration of the main part of the contactless power transmission device according to the present embodiment, which functions as both a power transmission device and a power reception device.

As shown in FIG. 1, the power transmission device 10 includes a chargeable/dischargeable power source 11 for operating the entire device, a switching circuit 12 for performing switching operation for transmitting power, and a power transmission device for converting the transmitted power into a magnetic field. It has a resonance system 13, a drive control circuit 14 for controlling the operation of switching elements that constitute the switching circuit 12, and a detection circuit 100 for detecting a predetermined condition.

The power receiving device 20 also includes a chargeable/dischargeable power source 21 for operating the entire device, a switching circuit 22 that rectifies the received power and converts it to a DC voltage, and a power transmitting resonance system 13 of the power transmitting device 10 that receives the transmitted power. , a drive control circuit 24 for operating the switching circuit 22, and a detection circuit 200 for detecting a predetermined condition.

As shown in FIG. 2, in the contactless power transmission device that is both the power transmitting device 10 and the power receiving device 20, the chargeable/dischargeable power supplies 11 and 12 can be implemented as, for example, chargeable/dischargeable secondary batteries.

As shown in FIG. 2, the power transmitting device 10 and the power receiving device 20 have full bridge circuits 12 and 22 as switching circuits.

The full-bridge circuits 12, 22 include a series body of first switching elements (12a, 22a) and second switching elements (12b, 22b), third switching elements (12c, 22d), and fourth switching elements (12c, 22d). A series body with the elements (12d, 22d) is connected in parallel and arranged between the power supplies 11, 21 and the grounds 16, 26. FIG.

The first to fourth switching elements (12a to 12d, 22a to 22d) can be composed of MOSFETs, and are individually controlled to be ON/OFF by drive voltages from drive control circuits 14 and 24, respectively. When the switching elements (12a to 12d, 22a to 22d) are composed of MOSFETs, the body diodes of the MOSFETs are arranged in a direction that allows current to flow only from the grounds 16, 26 to the power supplies 11, 21. be. As a result, when none of the first to fourth switching elements (12a to 12d, 22a to 22d) is in the OFF state, the full bridge circuits 12 and 22 function as full-wave rectifiers composed of four diodes. it will work.

Each of the resonance systems that become the power transmission resonance system 13 and the power reception resonance system 23 is configured as a series resonance system resonance circuit in which resonance coils 13a and 23a and resonance capacitors 13b and 23b are connected in series. Resonant circuits, which are the power transmission resonance system 13 and the power reception resonance system 23, are connected to the source-drain connection portion of a bridge circuit in which two sets of MOSFETs of the full bridge circuits 12 and 22 are vertically connected in series.

In FIG. 2, the power transmission resonance system 13 and the power reception resonance system 23 are shown as series resonance circuits in which the resonance coils 13a and 23a and the resonance capacitors 13b and 23b are connected in series. A resonance circuit of a parallel resonance system in which the resonance capacitors 13b and 23b are connected in parallel can also be configured. However, in this case, since the output from the full bridge circuit is directly supplied to the resonant capacitors 13b and 23b and a large current flows, it is necessary to insert an inductance in series.

The drive control circuits 14, 24 detect predetermined conditions (described later) by the detection circuits 100, 200, and based on the detected results, switch the switching elements (12a to 12d, 22a to 22d) Control each ON/OFF operation at a predetermined timing.

In the power transmission device 10 , the drive control circuit 14 operates the full bridge circuit 12 as an inverter circuit to generate alternating current to be applied to the power transmission resonance system 13 . Further, as will be described later, when performing self-excited oscillation in the power transmitting device 10, when performing PWM control for improving power transmission efficiency, and when decreasing transmitted power, pause (shutdown) operation control, When performing a recovery operation for recovering surplus power, the drive control circuit 14 performs operation control to turn ON/OFF the switching elements (12a to 12d) that constitute the full bridge circuit 12 at predetermined timings.

In the power receiving device 20, the drive control circuit 24 switches the switching elements (22a to 22d) constituting the full bridge circuit 22 when full-wave rectification is performed by the diodes incorporated in the switching elements of the full bridge circuit 22. It remains in the OFF state. Further, when performing synchronous rectification to improve power transmission efficiency, which will be described later, or when performing a recovery operation to return power from the power receiving device 20 side to the power transmitting device 10, the drive control circuit 24 configures the full bridge circuit 22. The switching elements (22a to 22d) are controlled to turn ON/OFF at a predetermined timing.

The present invention provides a safe non-contact power transmission device that can function as both a power transmission device and a power reception device in the non-contact power transmission device. Safety means being able to prevent damage to equipment components and improper use of rechargeable power sources. As a cause of damage to the parts of the device, for example, excessive voltage or excessive current flows in the capacitors and coils provided in the resonance systems 13 and 23, which damages the capacitors and coils. be done. Further, if any of the capacitor, coil, chargeable/dischargeable power source, and various circuits continues to be used in a state outside the appropriate temperature, damage to them is predicted. Furthermore, a chargeable/dischargeable power supply is unsafe to power the power supply with excessive current when the contactless power transmission device functions with the power receiving device. If the chargeable/dischargeable power supply is over-discharged when the contactless power transmission device functions as a power transmitting device, or if the chargeable/dischargeable power source is overcharged when the wireless power transmission device functions as a power receiving device, chargeable/dischargeable power supply insecure.

From these facts, excessive voltage of the resonance voltage of the coil, excessive current of the resonance current of the coil, temperature inside the power transmission device, excessive current when supplying power to the chargeable/dischargeable power supply, and excessive chargeable/dischargeable power supply At least one predetermined condition of a group of voltages is detected, and the drive control circuit controls each switching that constitutes the switching circuit so as to cut off power transmission or power reception by the contactless power transmission device according to the detection result. At this time, power transmission or power reception of the contactless power transmission device can be cut off by performing control to turn ON only the switching element on either the power supply side or the ground side of each switching element. Further, by controlling the switching element in this way, it is possible to cut off power transmission and reception while the resonance continues, so that power transmission and reception can be smoothly restarted after the power transmission and reception are cut off.

In the contactless power transmission device according to this embodiment, the resonance current detection circuits 15 and 25 can be used as examples of the detection circuits 100 and 200 . The resonance current detection circuits 15 and 25 may detect the current flowing through the lower switching elements in the switching elements forming the full bridge circuits 12 and 22 . For example, the resonance current detection circuits 15 and 25 are connected to the lower switching elements (12b and 22b) of the bridge circuit connecting the first switching elements (12a and 22a) and the second switching elements (12b and 22b). Lower switching element of a bridge circuit connecting first resistors (15a, 25a) for detecting flowing current, third switching elements (12c, 22d), and fourth switching elements (12d, 22d) and second resistors (15b, 25b) for detecting the current flowing through (12d, 22d).

In the resonance current detection circuits 15 and 25, the waveforms of the currents flowing through the two lower switching elements of the full bridge circuit detected by the first resistors (15a, 25a) and the second resistors (15b, 25b) are A resonance current waveform flowing through the power transmission resonance system 13 or the power reception resonance system 23 is obtained by performing appropriate processing such as inversion processing and synthesis processing.

The resonance current detection circuits 15 and 25 detect the resonance current waveforms flowing through the full bridge circuits 12 and 22 as described above, and the information on the voltage value of the resonance voltage obtained based on the current waveforms. 24 and used as information for operation control in the drive control circuits 14 and 24 .

In FIG. 2, the resonance current detection circuits 15 and 25 are the second switching elements (12b and 22b) arranged on the ground 16 side of the full bridge circuits 12 and 22, and the fourth switching elements (12d and 12d). 22d), an example in which resistors (15a, 25a, 15b, 25b) for current detection are arranged on the ground 16 side of the full bridge circuits 12, 22 has been described. However, in the present embodiment, the resonance current detection circuits 15 and 25 are configured to detect the current flowing through the switching elements (12a, 22a, 12c, 22c) on the power supply 11 and 21 side of the full bridge circuits 12 and 22. can be done.

However, in this case, it is necessary to install a resistor for current detection between the switching element (12a, 22a, 12c, 22c) and the power supply 11, 21, and even if the signal change is small, the resistor output itself has a high voltage. As a result, it becomes necessary to use electronic parts having a high withstand voltage as the electronic parts constituting the resonance current detection circuits 15 and 25 . For example, in the case where the contactless power transmission device according to the present embodiment is a device that transmits power for charging and discharging a battery of an electric vehicle, the power supply voltage value may be several hundred volts. Constructing the resonance current detection circuits 15 and 25 with electronic components that can withstand the high voltage leads to an increase in cost. Therefore, it is preferable that the resonance current detection circuits 15 and 25 are configured to detect the current flowing through the switching elements (12b, 22b, 12d, and 22d) on the ground 16 side in the full bridge circuits 12 and 22. FIG.

Based on the resonance current values detected by the resonance current detection circuits 15 and 25 in this manner, excessive currents of the resonance currents of the coils of the resonance systems 13 and 23 are detected. , 24 constitute a switching circuit, whichever of the power supply side (12a and 12c, 22a and 22c) or the ground side (12b and 12d, 22b and 22d) of each of the switching elements 12a to 12d and 22a to 22d that constitute the switching circuit. Only one switching element can be controlled to be ON. By controlling in this way, it is possible to stop the power transmission by the resonance system, so it is possible to prevent the resonance current of the resonance system from increasing due to the continuation of power transmission, and the damage to the coil due to the flow of excessive current. I can. On the other hand, since the resonance state can be continued, power transmission/reception can be efficiently restarted.

The resonance current can be detected by inserting a current detection resistor in the middle of the resonance system (detection IC) or by providing a current transformer. However, when the transmission output of the contactless power transmission device increases, the voltage of the power supply that supplies power to the bridge circuit increases, and may exceed the rated voltage of the detection IC. Furthermore, current trust has a problem of low responsiveness. With a simple configuration of placing a resistor on the ground side of the full bridge circuit or placing a resistor on the power side of the full bridge circuit, it is possible to detect the current value of the resonant current at high speed and with high accuracy, resulting in low cost. It is preferable from the viewpoint of enhancement and performance improvement.

For example, it is possible to lower the withstand voltage of the electronic components constituting the resonance current detection circuits 15 and 25 by separately providing a power supply for operating the resonance current detection circuits 15 and 25 on the high voltage side. Since the drive control circuits 14 and 24 are usually installed on the low voltage side, it is necessary to perform a voltage shift, configure a separate power supply, etc., which leads to an increase in cost and a complicated circuit configuration.

FIG. 3 is an image diagram showing the state of power transmission and reception in the contactless power transmission device according to the present embodiment.

As shown in FIG. 3, when the contactless power transmission device according to the present embodiment is used as the power transmission device 10 and the power reception device 20 to transmit and receive power, the coils in the power transmission device 10 are indicated by arrows 31 in the figure. When a current flows in the indicated direction, the magnetic field generated in the coil interlinks with the coil of power receiving device 20, and an electromotive force is generated in the coil of power receiving device 20 so as to cancel this magnetic field, in the direction indicated by arrow 32 in the figure. current flows through When the power transmission device 10 and the power reception device 20 have the same configuration as described above, the direction of the electromotive force is opposite to the direction of the interlinking magnetic lines of force between power transmission and power reception. 13 and the resonance coil 23a of the power receiving resonance system 23 of the power receiving device 20 are magnetically coupled to realize contactless power transmission 33 from the power transmitting device 10 to the power receiving device 20 .

[Operation of power transmission device]
Next, the operation of the contactless power transmission device according to the present embodiment when used as a power transmission device will be specifically described.

FIG. 4 is a circuit configuration diagram showing a configuration when the contactless power transmission device according to this embodiment is used as a power transmission device.

The configuration of the power transmission device 10 shown in FIG. 4 is the same as that described in FIGS. , a resonance coil 13a and a resonance capacitor 13b that constitute the power transmission resonance system 13, a drive control circuit 14 that controls the operation of each switching element (12a, 12b, 12c, 12d) of the full bridge circuit 12, and a full bridge circuit. and a resonance current detection circuit 15 for detecting a resonance current flowing through the power transmission resonance system 13 from the flowing current.

The four switching elements 12a, 12b, 12c, and 12d are all composed of MOSFETs, and when the signals applied from the four terminals A, B, C, and D of the drive control circuit 14 are High, they are conductive and current flow. Also, as shown in FIG. 4, the body diode of the MOSFET is arranged in the direction in which the current flows from the ground 16 to the power supply 11 side.

In the power transmission device 10 shown in FIG. 4, the resonance current detection circuit 15 includes two resistors 15a and 15b for detecting current flowing through the two switching elements 12b and 12d arranged on the ground 16 side of the full bridge circuit 12, as well as , resistors 15c, 15d, 15e, and 15g, an amplifier 15f, and a power supply 15h as an inversion synthesis circuit, and by inverting the current flowing through the switching element 12b and synthesizing it with the current flowing through the switching element 12d, the resonance current A detected voltage is output to the terminal M.

The voltage output to this terminal M is a detected voltage obtained by detecting and voltage-converting the resonance current of the coil of the resonance system 13 . In other words, the inversion synthesis circuit is also a coil resonance current detection circuit, and can function as an example of the detection circuit 100 . When it is detected that the resonance detection value output to the terminal M is excessive, the drive control circuit controls the power supply side (here, 12a and 12c) or the ground side of each switching element constituting the switching circuit based on the detection result. Control can be performed to turn on only one of the switching elements (12b and 12d here). As a result, it is possible to prevent the coil from being damaged due to excessive current flow. On the other hand, since the resonance state can be continued, power transmission/reception can be efficiently restarted.

A resonance voltage detection circuit can be provided to detect the voltage of the capacitor in the resonance system. A resonance voltage detection circuit can function as an example of the detection circuit 100 . When the resonance system capacitor voltage detected by the resonance voltage detection circuit is detected to be an excessive voltage, the drive control circuit configures the switching circuit based on the detection result. can be controlled to turn ON only the switching elements on either the power supply side (here 12a and 12c) or the ground side (here 12b and 12d). As a result, it is possible to prevent the coil from being damaged by excessive voltage. On the other hand, since the resonance state can be continued, power transmission/reception can be efficiently restarted. The resonance voltage detection circuit may directly detect the voltage across the capacitor, but it is also possible to detect it from the resonance current. In this case, the amount of current that charges the capacitor over a half cycle is obtained from the capacity of the resonant capacitor and the resonant current, and the maximum voltage that charges the capacitor is detected. There is a way to detect it.

Also, the current value flowing through the two switching elements 12 b and 12 d of the resonance current detection circuit 15 is the resonance current of the coil of the resonance system 13 . A resonance current is detected by two resistors 15a and 15b. A resonant current detection circuit can function as an example of the detection circuit 100 . When the resonance current value is detected as an excessive current, based on the detection result, the drive control circuit controls the power supply side (here 12a and 12c) or the ground side (here 12b) of each switching element constituting the switching circuit. and 12d) can be controlled to turn ON only the switching element. As a result, it is possible to prevent damage to the coil due to excessive current flow. On the other hand, since the resonance state can be continued, power transmission/reception can be efficiently restarted.

As a method of detecting an excessive current, there is a method of determining a threshold in advance and detecting an excessive current when the detected current value exceeds the threshold.

Further, in the power transmission device 10 shown in FIG. 4, a capacitor 17 serving as a bypass capacitor is arranged between the power supply 11 and the ground 16, and the resonance current flowing through the power transmission resonance system 13 is normally generated by a capacitor with a small AC resistance component. flows through 17. Further, in the power transmission device 10 shown in FIG. 4, a current detection resistor 18 is arranged between the full bridge circuit 12 and the ground 16 to detect the current flowing out from the power supply 11 by the voltage drop caused by the resistance.

A current detection resistor 18 that detects the current flowing out from the power supply 11 functions as a current detection circuit. A current detection circuit can function as an example of the detection circuit 100 . When the current value detected by the current detection circuit from the power supply is detected to be an excessive current, the drive control circuit detects the power supply side (here, 12a and 12c) or the ground side (here, 12b and 12d) can be controlled to turn ON only. As a result, it is possible to prevent the coil from being damaged due to excessive current from the power supply. On the other hand, since the resonance state can be continued, power transmission/reception can be efficiently restarted.

Also, a power supply voltage detection circuit for detecting the voltage of the power supply 11 can be provided so as to measure the power supply voltage. The power supply voltage detection circuit can function as an example of the detection circuit 100 . When the voltage of the power supply detected by the power supply voltage detection circuit is detected to be an undervoltage, the drive control circuit controls the power supply side of each switching element (here, 12a and 12c) constituting the switching circuit based on the detection result. ) or on the ground side (here, 12b and 12d). As a result, the power supply can be prevented from being over-discharged, so that the power transmission device can be used under safe conditions. On the other hand, since the resonance state can be continued, power transmission/reception can be efficiently restarted.

By providing the capacitor 17 and the resistor 18 , the power output from the power supply 11 can be detected based on the current flowing through the power transmission device 10 other than the resonance current. Therefore, it is possible to detect the power that is actually transmitted and use it for controlling the operation of the switching circuit in the drive control circuit.

The resistor 18 can similarly detect transmitted power even if it is placed between the power supply 11 and the full bridge circuit 12, but placing it in a high voltage system requires a high withstand voltage. Therefore, it is more preferable to arrange it on the ground side as shown in FIG. Also, the bypass capacitor 17 and the resistor 18 are not essential in the power transmission device 10 described in this embodiment.

Also, although not shown in the drawings, it is possible to enable the temperature detection circuit to detect the temperature of parts that should be prevented from being damaged in the contactless power transmission device, such as resonance system coils, various circuits, and power supplies. The temperature detection circuit can be realized by known means such as a temperature detection thermistor. A temperature detection circuit can function as an example of the detection circuit 100 . When the temperature detected by the temperature detection circuit is detected to be too high or too low, the drive control circuit controls the power supply side (here, 12a and 12c) or the ground side of each switching element constituting the switching circuit based on the detection result. Control can be performed to turn on only one of the switching elements (12b and 12d here). As a result, damage to various parts can be prevented, and power transmission can be cut off outside the appropriate temperature range. On the other hand, since the resonance state can be continued, power transmission/reception can be efficiently restarted.

As a method of detecting whether the temperature is too high or too low, the upper limit and/or lower limit of the temperature are determined in advance, and a method of detecting whether the detected temperature is within the range of the upper limit and/or the lower limit is used. be.

As described above, based on the detection results of the predetermined conditions, the drive control circuit switches the switching elements on either the power supply side (here, 12a and 12c) or the ground side (here, 12b and 12d) of the switching elements that make up the switching circuit. Control can be performed to turn ON only the element. This control has the advantage that power transmission and reception can be efficiently resumed because the resonance state can be continued, but power is consumed even during this control. Therefore, when power transmission/reception is not resumed even after a predetermined period of time, the contactless power transmission device can be turned off. This makes it possible to reduce power consumption as much as possible.

In FIG. 4, in addition to the above-described terminals A to D and terminal M, the intermediate portion between the first switching element 12a and the second switching element 12b of the full bridge circuit 12 is used for the explanation of the operation below. A terminal E is connected between the third switching element 12c and the fourth switching element 12d of the full bridge circuit 12, and a terminal F is connected between the resonance coil 13a and the resonance capacitor 13b of the power transmission resonance system 13. , a terminal K indicating the voltage of the first resistor 15a of the current detection unit 15 and a terminal L indicating the voltage of the second resistor 15b are provided.

Further, in the following description, as indicated by the arrows in the drawing, the direction of flow from the power supply side to the ground side is assumed to be the positive direction of the resonance currents H, I, and J. FIG.

In FIG. 4, a to d indicated by an implementation line or a dotted line and arrows indicate currents flowing through the full bridge circuit 12 during PWM control, which will be described with reference to FIG. Details will be described in the description of FIG.

a. Startup and Resonance Current Control FIG. 5 is a timing chart showing a terminal voltage waveform and a resonance current waveform during the power transmission operation of the power transmission device described in this embodiment.

In FIG. 5, the horizontal squares indicate the timing of the motion by labeling. In addition, the grids in the vertical direction indicate High (hereinafter referred to as "Hi") and Low (hereinafter referred to as "Lo") levels of the applied voltage, and the waveforms of the resonance current and resonance voltage is labeled in the height direction. It should be noted that each timing chart used in the following description also shows the operation timing and the waveforms of the applied voltage, the resonance voltage, and the resonance current, as in FIG.

First, a) at the start timing, the drive control circuit 14 turns on the first switching element 12a and the fourth switching element 12d of the full bridge circuit 12, and turns off the second switching element 12b and the third switching element 12c. , when the terminal voltage E is set to Hi and the terminal voltage F is set to Lo, a resonance current flows so as to charge the power transmission resonance system 13, and when the resonance capacitor 13b is charged, a current flows in the opposite direction. , resonance current I begins.

In the power transmission device described in this embodiment, the voltage applied to the terminal E and the terminal F is further controlled according to the resonance timing at this time.

Specifically, after the start-up described above, the polarity of the resonance current I (+ is positive, that is, the direction of arrow H shown in FIG. direction), the voltage applied from the drive control circuit 14 to the four switching elements 12a to 12d is controlled, and when the polarity of the resonance current I is "positive", the full bridge circuit 12 The first switching element 12a and the fourth switching element 12d are turned on, the second switching element 12b and the third switching element 12c are turned off, the terminal voltage E is set to Hi, and the terminal voltage F is set to Lo. On the other hand, when the polarity of the resonance current I is "negative", the second switching element 12b and the third switching element 12c of the full bridge circuit 12 are turned on, and the first switching element 12a and the fourth switching element are turned on. 12d is turned off, the terminal voltage E is set to Lo, and the terminal voltage F is set to Hi.

That is, the point in time when the resonance current I in FIG. 5 becomes 0 is detected, and at that timing, the four gates A to D of the drive control circuit 14 are controlled so that the resonance current I changes from a positive value to a negative value. When the resonance current I changes from a negative value to a positive value, the terminal voltage F is set to Hi and the terminal voltage F is set to Lo.

By doing so, for example, at the timing shown as b) drive start timing in FIG. The potential of the other terminal G of the resonance capacitor 13b rises from 2V to 3V accordingly. At this time, since the terminal E side of the resonance coil 13a is fixed to the ground potential, the voltage across the resonance coil 13a has a potential difference of 3 V indicated by the dashed arrow in FIG. In accordance with this potential difference, a current as indicated by resonance current I begins to flow through the resonance coil 13a. This current continues to increase until the voltage across the resonance capacitor 13b becomes zero, at which point the current flowing through the resonance coil 13a reaches its maximum. After that, since the energy of the magnetic field stored in the resonance coil 13a charges the resonance capacitor 13b, the potential of the resonance capacitor 13b continues to drop until the resonance current I becomes 0, and the potential of the terminal G drops to -3V. .

At this point, when the gate signal from the drive control circuit 14 is controlled so that the terminal E is at the power supply voltage and the terminal F is at the ground potential, the voltage at the terminal F drops by 1 V, which is the power supply voltage, and this causes the resonance capacitor to 13b, a potential difference is applied to the resonance coil 13a as indicated by the dashed arrow with a length of 4V. Therefore, the resonance current begins to flow and the resonance voltage itself increases in the same way as before.

Such an operation is continued, and a current flows from the full bridge circuit 12 in a direction to compensate for the resonance current I flowing in the power transmission resonance system 13, and power is injected into the power transmission resonance system 13. Therefore, resonance in the power transmission resonance system 13 As it increases, finally, the power consumed by the resistance of the coil and the like becomes equal to the power injected, and the resonance continues stably. Just by setting the terminal voltage E to Hi as in the above-described a) activation operation at the activation timing, the resonance generated in the power transmission resonance system 13 is gradually attenuated by the resistance component of the resonance circuit, but the drive control circuit 14 By controlling ON/OFF of each of the switching elements 12a to 12d of the full bridge circuit 12, the resonance in the power transmission resonance system 13 can be kept increased.

In the contactless power transmission device described in the present embodiment, the operation described above starts so as to maintain the peak point of the overall resonance characteristics of the power transmission/reception resonance system, and then oscillation continues. A power transmission device that performs self-excited oscillation is configured.

More specifically, in the power transmission device 10 of the present embodiment, the current applied from the full bridge circuit 12 to the power transmission resonance system 13 in order to maintain resonance in the power transmission resonance system 13 is the resonance current flowing through the power transmission resonance system 13. applied in synchronism with I. When the power transmission device 10 and the power reception device 20 are arranged in a state in which power transmission is possible, the resonance current I in the power transmission resonance system 13 is It will flow according to the resonance characteristics in the coupled state. Therefore, as in the power transmission device 10 of the present embodiment, the resonance current excited by the voltage applied at the start timing is measured, and the drive control circuit 14 controls the full bridge circuit 13 according to the change in the polarity of the resonance current. is applied to the resonance circuit by controlling the current corresponding to the resonance characteristics of the power receiving device 20 coupled with the power receiving resonance system 23 . Therefore, regardless of the distance between the power transmission device 10 and the power reception device 20 and the presence or absence of a foreign object between the power transmission device 10 and the power reception device 20, the power transmission resonance system 13 of the power transmission device 10 shown in the present embodiment can be operated in an optimal state. can perform self-excited oscillation to resonate.

In the power transmission device 10 of the present embodiment, the resonance current of the power transmission resonance system 13 is detected from the current flowing through the full bridge circuit 12 by the resonance current detection circuit 15, and the switching elements of the full bridge circuit 12 are switched according to the polarity. For example, even if the distance between the power transmission device 10 and the power reception device 20 changes, or if a foreign object enters between the power transmission resonance system 13 and the power reception resonance system 23, the power transmission resonance system 13 at that time is controlled. The timing of current application to the power transmission resonance system 13 can be changed according to the coupling state between the power transmission resonance system 23 and the power reception resonance system 23 . As a result, it is not necessary to measure the resonance characteristics from the states of the power transmission resonance system 13 and the power reception resonance system 23 to set the characteristics of the resonance coil 13a and the resonance capacitor 13b of the power transmission resonance system 13 in advance. In order to change the circuit characteristics of the resonant system according to the coupling state between the system 13 and the power receiving resonant system 23, it is not necessary to change the circuit characteristics of the power transmitting coil 13a and the power transmitting capacitor 13b. As a result, in the power transmission device 10 described in this embodiment, the circuit configuration of the power transmission resonance system 13 can be simplified, and as a result, the size and cost of the power transmission device 10 can be reduced.

In a state where the power transmitting resonance system 13 and the power receiving resonance system 23 are magnetically coupled, for example, when the load of the power receiving device 20 decreases, the resonance voltage on the power receiving side increases, and as a result, the power transmitting resonance system 13 resonance voltage also rises. In this way, if the resonance voltage is left in a raised state, the resonance voltage may further rise and exceed the withstand voltage of the parts constituting the resonance system circuit.

For this reason, in the power transmission device 10 shown in the present embodiment, a resonance voltage detection circuit (not shown) that detects the resonance voltage appearing at the terminal G of the power transmission resonance system 13 is provided. The resonance voltage can be lowered by suspending the supply of power to be injected from the full bridge circuit 12 to the power transmission resonance system 13, or by causing a current to flow in the direction opposite to the resonance current I.

For example, the polarity of the resonance current I is negative, that is, at the timing when the resonance current I flows from the terminal F to the terminal E, the terminal voltage E is the ground potential (for convenience, referred to as "negative"), and the terminal voltage F is the power supply voltage. Control is performed so that the switching elements 12b and 12c of the full bridge circuit 12 are turned on and the switching elements 12a and 12d are turned off so as to obtain a voltage (referred to as "positive" for convenience). Further, the polarity of the resonance current I is positive, that is, at the timing when the resonance current I flows from the terminal F to the terminal E, the terminal voltage E is positive and the terminal voltage F is negative. The switching elements 12a and 12e are turned on, and the switching elements 12b and 12c are turned off.

By operating the drive control circuit in this manner, a current in the direction opposite to the resonance direction is applied to the power transmission resonance system 13, and the action of reducing the resonance voltage and the resonance current works.

Therefore, in the power transmitting device 10 according to the present embodiment, based on the resonance current flowing through the full bridge circuit 12 detected by the resonance current detection circuit 15, the drive control circuit 14 detects the switching elements (12a to 12d) of the full bridge circuit 12. ), it is possible to effectively avoid a situation in which the circuit constituting the resonance circuit exceeds the withstand voltage and is damaged due to an excessive resonance voltage.

Note that in a state in which the drive control circuit 14 is performing an operation to reduce the resonance voltage in response to the increase in the resonance voltage and the resonance current in the power transmission device 10, the load on the power reception device 20 increases, When the value of the resonance voltage becomes small, this is detected by the resonance current detection circuit 15, and the current flowing from the full bridge circuit 12 to the power transmission resonance system 13 is increased as in the above-described self-oscillation. to control the operation of By controlling in this way, the magnitude of the resonance voltage applied to the power transmission resonance system 13 can be maintained at a predetermined voltage value.

b. PWM Control Next, operations for power control and power saving in the power transmission circuit described in this embodiment will be described.

FIG. 6 is a diagram for explaining PWM control for controlling the voltage width applied to the switching elements of the full bridge circuit in the power transmission device according to this embodiment.

FIG. 6 shows the Hi and Lo states of the four terminal voltages A, B, C, and D of the drive control circuit 14, the current I flowing through the first resistor 15a of the resonance current detection circuit 15, and the second resistor Also shown are the current J flowing through 15b, the inverted signal of the detected current I generated in the inverted synthesis circuit, and the voltage waveform at the inverted synthesized terminal M obtained by synthesizing the detected current J with this signal.

In FIG. 6 , in the left part of the drawing, the self-excited oscillation operation described above is performed to operate the full bridge circuit in the direction to maintain the resonance current in the power transmission resonance system 13 .

In this way, the application time of the voltage applied from the drive control circuit 14 to the four switching elements 12a to 12d of the full bridge circuit 12 in a state in which the power transmission resonance system 13 is stably operated by the self-oscillation operation. PWM control is performed to change the

In order to explain the flow of the resonance current during PWM control, the directions of current flow are indicated by symbols a to d in FIG. In symbols a to d shown in FIG. 4, the direction of the resonance current flowing in the same direction as the arrow H is indicated by solid arrows, and the direction of the resonance current in the opposite direction is indicated by non-filled arrows. In addition, the direction of the resonance current and the state of the switching element can be displayed at the same time by showing the path of the current when the switching element is in the ON state with a solid line and the path when the switching element is in the OFF state with a broken line. .

Therefore, the forward current resonating in the power transmission resonance system 13 in the OFF state of the switching element is represented by symbol b, and flows through the body diode of the switching elements 12c and 12b. Further, in a state where the first switching element 12a and the fourth switching element 12d are turned off and the second switching element 12b and the third switching element 12c are turned on, the reverse current resonating in the power transmission resonance system 13 is It flows in the path and direction indicated by symbol c.

FIG. 6 shows, as an example, a state in which PWM control is performed to halve the pulse width of the Hi voltage applied to the gate of each switching element. In FIG. 6, the dotted line indicates the voltage application period when PWM control is not performed so that the voltage applied to each terminal from gate A to gate D is decreased by PWM control. .

In FIG. 6, after the timing shown as a) PWM control, the voltage applied to the switching element a and the switching element d changes from Hi to Lo due to PWM control. state to Lo state, and the terminal voltage F changes from Lo state to Hi state. At this time, the reason why the terminal voltage E is lower than the Lo state and higher than the Hi voltage is that the voltage across the parasitic diode of the MOSFET used as the switching element is superimposed. It is caused by

The behavior of the terminal voltage E and the terminal voltage F generated by PWM-controlling the operating voltage applied to the switching element is the same, albeit in the opposite direction, when the switching elements 12b and 12c having opposite polarities of the resonance current are in the ON state. occur.

In this way, when the drive voltage applied to each switching element forming the full bridge circuit is PWM-controlled, among the switching elements forming the full bridge circuit 12, the lower stage of the series connection of the switching elements shown on the left side of the figure The resonance current I flowing through the switching element in the lower part of the second series connection shown on the right side of the figure and the resonance current J flowing through the switching element in the lower part of the second series connection shown on the right side of the figure can be generated by operating the switching elements under PWM control. It fluctuates greatly when switching between the state and the Lo state. However, in the power transmitting device of the present embodiment, the terminal voltage M is obtained by inverting and synthesizing the resonance current I and the resonance current J in the inversion synthesizing circuit. Therefore, as shown in FIG. 6, PWM control is not performed. As in the case, the resonance current can be grasped.

For this reason, while power is being transmitted between the power transmission device and the power reception device, it is possible to grasp the resonance current in the state of magnetic coupling at all times, and control the self-excited oscillation control and the control to reduce the resonance voltage described above. It can be performed.

By performing PWM control, it is possible to reduce the power transmitted by the power transmitting device, so that non-contact power transmission with low power consumption can be realized. In addition, by performing PWM control, it is possible to adjust the magnitude of the resonance voltage by changing the logic in the drive control circuit. It is no longer necessary to use PAM (Pulse Amplitude Modulation) control for changing the voltage itself, and it is possible to reduce the size and cost of the power transmission device.

c. Power Transmission Suspension (Interruption) and Recovery Operation FIG. 7 is a circuit configuration diagram of the power transmission device according to the present embodiment for explaining current flow when power transmission is suspended (interrupted).

FIG. 8 is a timing chart for explaining the operation of suspending (cutting off) power transmission according to the polarity of the resonance current in the power transmission device according to this embodiment.

In the state where power is being transmitted from the power transmitting device to the power receiving device by the self-excited oscillation operation and the PWM control operation described above, when power transmission is temporarily suspended (cut off), b) Pause ( Shutdown) As shown as additional timing, the drive control circuit 14 is controlled to set the gate terminals B and D to Hi and the gate terminals A and C to Lo, and the full bridge circuit 12 is grounded. The switching element 12b and the switching element 12d arranged on the 16 side are controlled to be ON, and the switching element 12a and the switching element 12c arranged on the power supply 11 side are controlled to be OFF.

By doing so, the resonance current H flows only between the elements on the ground side of the full bridge circuit 12 and the transmission resonance system, as indicated by arrows a and c in FIG. 7 . In the power transmission device of the present embodiment, the resonance current detection circuit 15 detects the current I and the current J flowing through the two elements on the ground side of the full bridge circuit 12. Therefore, arrows a and c shown in FIG. can be grasped as a resonance current I and a resonance current J shown in FIG.

At this time, in the power transmission device 10 according to the present embodiment, the current I flowing through the first resistor 15a is reversed and combined with the current J flowing through the second resistor 15b. Although the voltage value at M is twice the voltage value during self-oscillation control or PWM control, the phase, that is, the timing at which the resonance current becomes 0, is the same. Therefore, when resuming power transmission from a pause (shutdown) state, ON/OFF control of each switching element of the full bridge circuit 12 is paused (shutdown) in accordance with the timing of the resonance current detected by the resonance current detection circuit 15. ) can be immediately resumed at the same timing as the operation timing before entering the state.

In the power transmission device of the present embodiment, the current flowing through the switching elements on the ground side of the full bridge circuit is detected in order to keep the withstand voltage of the resonance current detection circuit low. It is also possible to employ a configuration in which a resonance current detection circuit detects the current value flowing through the switching elements on the power supply side that constitute the full bridge circuit. In this way, when the resonance current detection circuit is configured to detect the current flowing through the switching elements (A, C) on the power supply side of the full bridge circuit, when power transmission is suspended (cut off), the drive With the terminals A and C of the control circuit set to Hi and the terminals B and D of the control circuit set to Lo, the resonance current H of the power transmission resonance system is controlled to flow through the power supply side of the full bridge circuit 12 . By doing so, it is possible to continue to grasp the resonance current waveform in the rest (interruption) state, and to immediately return to the power transmission state from the rest (interruption) state.

FIG. 9 shows a timing chart when the power transmission device according to the present embodiment operates in a power reception mode in which power remaining in the power transmission resonance system is recovered after entering a rest (shutdown) state.

As described above, the power transmission device 10 described in this embodiment may use a secondary battery as the power source 11. In this case, after the power transmission from the power transmission device 10 is stopped, the power transmission resonance system 13 If the remaining power can be recovered, the power of the secondary battery as the power source 11 can be recovered accordingly.

As shown in FIG. 9, in the resting state, in the full bridge circuit 12, the terminal voltages B and D are set to Hi, and the terminal voltages A and C are set to Lo so that only the two switching elements 12b and 12d on the ground side are turned on. After that, when the resonance current is positive, the terminal voltages B and C are set to Hi, and the terminal voltages A and D are set to Lo. When the resonance current is negative, the terminal voltages A and D are set to Hi, and the terminal By controlling the voltages B and C to Lo, a current flows through the full bridge circuit 12 in a phase opposite to that in the power transmission state, so operation in the power reception mode is performed.

In the power transmission device according to the present embodiment, the currents flowing through the two ground-side switching elements of the full bridge circuit are inverted and combined to form the output of the resonance current detection circuit. , the detected waveform of the resonance voltage is the same as in the power transmission mode and the pause (shutdown) mode. Therefore, in the power transmission device according to this embodiment, it is possible to smoothly switch among the power transmission mode, the pause (shutdown) mode, and the power reception mode.

In this power reception mode, the state in which the control of the operation pulse to each switching element of the full bridge circuit 12 from the drive control circuit 14 with respect to the phase of the resonance current is reversed from the power transmission mode is the state in which the power reception device 20 described later is in full operation. The control is the same as that of the bridge circuit 22 during the power receiving operation.

As described above, in the power transmission device described in this embodiment, the currents of the two ground-side switching elements of the full bridge circuit are detected, and each switching element of the full bridge circuit is turned on according to the phase of the detected current. /OFF timing is switched. By doing so, it is possible to control ON and OFF of each switching element of the full bridge circuit in the power transmission device according to the resonance waveform in the state of being magnetically coupled with the power reception device. It is possible to transmit power with little power transmission loss by automatically following changes in the resonance current waveform due to changes in the distance between them and the presence or absence of foreign objects.

In addition, since the magnitude of the resonance voltage of the power transmission resonance system that is magnetically coupled to the power reception resonance system can be grasped, the resonance power can be reduced before the resonance voltage becomes excessive. Even when the load is reduced, it is possible to effectively prevent the circuit of the power transmission resonance system from being damaged by an excessive voltage exceeding the withstand voltage.

In addition, by detecting the current flowing through each of the switching elements on the ground side of the full-bridge circuit using a resonant current detection circuit, PWM control that reduces the transmitted power, control in rest (shutdown) mode, and control in power reception mode can be performed. , a configuration that can be performed based on continuous, same-phase resonance voltage waveforms can be realized at low cost.

[Operation of power receiving device]
Next, the operation of the contactless power transmission device according to the present embodiment when used as a power receiving device will be specifically described.

FIG. 10 is a circuit configuration diagram showing a configuration when the contactless power transmission device according to this embodiment is used as a power receiving device.

In the contactless power transmission device described in this embodiment, as shown in FIGS. 1 and 2, a device having the same configuration can be used as both a power transmission device and a power reception device. FIG. 10 will be described using the names and symbols of the components of the power receiving device described in FIG. The configuration is the same as that of the shown power transmission device. In other words, the logic portion of the drive control circuit is provided with both the power transmitting device and the power receiving device, and by appropriately switching between them, one contactless power transmission device can be used as both a power transmitting device and a power receiving device. can do.

The configuration of the power receiving device 20 according to the present embodiment shown in FIG. 10 is the same as that described with reference to FIGS. a full bridge circuit 22, a resonance coil 23a and a resonance capacitor 23b that form a power receiving resonance system 23, and a drive control circuit 24 that controls the operation of each switching element (22a, 22b, 22c, 22d) of the full bridge circuit 22. and a resonance current detection circuit 25 for detecting a resonance current flowing through the power receiving resonance system 23 from the current flowing through the full bridge circuit.

FIG. 10 shows that the four switching elements 22a to 22d are all composed of MOSFETs, and that the switching elements are conductive when the signals applied from the four terminals A to D of the drive control circuit 24 are High. 4, the body diode of the MOSFET is arranged in the direction in which the current flows from the ground 26 to the power supply 21 side. Furthermore, the configuration of the resonance current detection circuit 25 is the same as that of the resonance current detection circuit 15 of the power transmission device 10, and detects the current flowing through the two switching elements 22b and 22d arranged on the ground 26 side of the full bridge circuit 22. It is equipped with two resistors 25a and 25b and an inverse synthesizing circuit, and a resonant voltage is output to the terminal M from the inversely synthesizing resonant current waveform.

The voltage output to this terminal M is the detection voltage of the resonance current of the coil of the resonance system 23 . In other words, the inversion synthesis circuit is a coil resonance current detection circuit, and can function as an example of the detection circuit 200 . When it is detected that the resonance current value output to the terminal M is an excessive current, the drive control circuit controls the power supply side (here, 22a and 22c) of each switching element constituting the switching circuit or the ground based on the detection result. It is possible to perform control to turn on only one of the switching elements on either side (here, 22b and 22d). As a result, it is possible to prevent the coil from being damaged due to excessive current flow.

As a method of detecting an excessive voltage, there is a method of determining a threshold in advance and detecting an excessive voltage when the detected voltage exceeds the threshold.

Also, the current value flowing through the two switching elements 22 b and 22 d of the resonance current detection circuit 25 is the resonance current of the coil of the resonance system 23 . A resonance current is detected by two resistors 25a and 25b. A resonant current detection circuit can function as an example of the detection circuit 200 . When the resonance current value is detected as an excessive current, based on the detection result, the drive control circuit controls the power supply side (here, 22a and 22c) or the ground side (here, 22b) of each switching element that constitutes the switching circuit. and 22d) can be controlled to turn on only one of the switching elements. As a result, it is possible to prevent damage to the coil due to excessive current flow.

Also, a resonance voltage detection circuit for detecting the voltage of the capacitor in the resonance system can be provided. A resonance voltage detection circuit can function as an example of the detection circuit 200 . When the resonance system capacitor voltage detected by the resonance voltage detection circuit is detected to be an excessive voltage, the drive control circuit configures the switching circuit based on the detection result. can be controlled to turn ON only switching elements on either the power supply side (here, 22a and 22c) or the ground side (here, 22b and 22d). As a result, it is possible to prevent the coil from being damaged by excessive voltage. The resonance voltage detection circuit may directly detect the voltage across the capacitor, but it is also possible to detect it from the resonance current. In this case, the amount of current that charges the capacitor over a half cycle is obtained from the capacity of the resonant capacitor and the resonant current, and the maximum voltage that charges the capacitor is detected. There is a way to detect it.

As shown in FIG. 10, the power receiving device also has a bypass capacitor 27 between the power supply 21 and the ground 26, and the resonance current flowing through the power receiving resonance system 23 normally has a small AC resistance component. It flows through capacitor 27 . Further, as in the power transmission device 10 described above, a current detection resistor 28 is arranged between the full bridge circuit 22 and the ground 26 to detect the current flowing into the power supply 21 by the voltage drop caused by the resistance. The power output from the power source 21 can be detected based on the current flowing through the power receiving device 20 other than the resonance current. Power can be detected. Note that the resistor 28 may be arranged between the power supply 21 and the full bridge circuit 22 in the same manner as in the power transmitting device 10, and the bypass capacitor 27 and the resistor 28 may be provided in the power receiving device 20 described in this embodiment. It's not mandatory.

A current detection resistor 28 that detects the current flowing into the power supply 21 can function as a current detection circuit. The current detection circuit can function as an example of the detection circuit 200 . When the current detection circuit detects that the current value to the power supply is excessive, based on the detection result, the drive control circuit detects the power supply side of each switching element that constitutes the switching circuit (here, 22a and 22c) or the ground side (here, 22b and 22d) can be controlled to turn ON only. As a result, it is possible to prevent excessive current from flowing to the power supply, so that the power transmission device can be used under safe conditions.
If the power source is simply a secondary battery, these excessive currents correspond to overcharge currents, and in the case of the power transmission side, they correspond to overdischarge currents. It is important from the viewpoint of heat generation, ignition, life, etc.

Also, a power supply voltage detection circuit for detecting the voltage of the power supply 21 can be provided so as to measure the power supply voltage. The power supply voltage detection circuit can function as an example of the detection circuit 200 . When the voltage of the power supply detected by the power supply voltage detection circuit is detected to be an excessive voltage, based on the detection result, the drive control circuit detects the power supply side (here, 22a) of each switching element that constitutes the switching circuit switching circuit. and 22c) or the ground side (here, 22b and 22d) can be controlled to turn ON only. As a result, it is possible to prevent a so-called overcharge state in which an excessive voltage is applied to the power supply, so that the power transmission device can be used under safe conditions.

Furthermore, although not shown in the drawing, it is possible to enable temperature detection by a temperature detection circuit for parts to be prevented from being damaged in the non-contact power transmission device, such as resonance system coils, various circuits, and power supplies. The temperature detection circuit can be realized by known means such as a temperature detection thermistor. A temperature detection circuit can function as an example of the detection circuit 200 . When the temperature detected by the temperature detection circuit is detected to be too high or too low, the drive control circuit controls the power supply side (here, 22a and 22c) or the ground side of each switching element constituting the switching circuit based on the detection result. Only one of the switching elements (22b and 22d here) can be controlled to be ON. As a result, damage to various parts can be prevented, and power transmission can be cut off outside the appropriate temperature range.

As a method of detecting whether the temperature is too high or too low, the upper limit and/or lower limit of the temperature are determined in advance, and a method of detecting whether the detected temperature is within the range of the upper limit and/or the lower limit is used. be.

As described above, based on the detection result of a predetermined condition, the drive control circuit switches either the power supply side (here, 22a and 22c) or the ground side (here, 22b and 22d) of each switching element that constitutes the switching circuit. Control can be performed to turn ON only the element. On the other hand, this control has the advantage that power transmission and reception can be resumed efficiently because the resonance state can be continued, but power is consumed even during this control. Therefore, when power transmission/reception is not resumed even after a predetermined period of time, the contactless power transmission device can be turned off. This makes it possible to reduce power consumption as much as possible.

In addition to the above-described terminals A to D and M, terminals E, F, G, K, and L are provided in the same manner as in the power transmission device for use in the description of operations below. Also, the case where the resonance current flowing through the resonance coil 23a is in the direction of the arrow H, and the direction in which the current I and the current J flow from the power supply side to the ground side will be described as the positive direction of the resonance currents H, I, and J. FIG.

Further, in FIG. 10, reference characters a to d indicate the flow of current when the power receiving current received by the power receiving resonance system 23 is rectified by the full bridge circuit 22 functioning as a rectifying circuit. Currents a to d flowing in the power receiving device 10 shown in FIG. 10 are shown as currents flowing in the power transmitting device in association with the current directions of the currents a to d shown in FIG. 4 and the states of the switching elements. That is, a filled arrow indicates a current flowing through the resonance coil 23a in the direction of arrow H, a solid arrow indicates a current flowing in the opposite direction, and a dashed line indicates a current path when all switching elements are off. , the current path when driving the switching element is shown by a solid line.

Since the power receiving device 20 uses the body diodes of the switching elements 22 a to 22 d for detection, the path shown as the current a is different from that of the power transmitting device 10 .

a. Synchronous Rectification Control Operation FIG. 11 is a diagram showing a terminal voltage waveform and a resonance current waveform during power transmission operation of the power receiving device described in this embodiment.

As shown in FIG. 11, in the power receiving device 20, the operating voltages of the four switching elements forming the full bridge circuit 22 are all Lo when power transmission from the power transmitting device 10 is started.

At this time, to the terminals E and F, a voltage is applied that changes between Hi and Lo according to the phases of the resonance voltage waveform and the resonance current waveform. A voltage drop corresponding to the body diode of each of the switching elements 22a to 22d is superimposed on the resonance voltage waveform, as indicated by symbols b) and e) in the terminal E voltage, for example.

On the other hand, when the resonance current waveform is "negative", as described as a) synchronous rectification addition timing in FIG. is controlled to Lo, the current flows through the main body of the switching element without passing through the body diode. The upper bulge disappears (c and f in the figure), and a clear rectangular rectified waveform is obtained as indicated by d and g in the figure.

As described above, in the power receiving device 20 according to the present embodiment, by operating the switching elements of the full bridge circuit 22 functioning as a rectifying circuit in synchronization with the phase of the resonance current flowing in the power receiving resonance system 23, the voltage generated by the body diode is With no drop, the resonance voltage can be rectified to a DC voltage with higher efficiency.

As shown in FIG. 11, the voltage waveform of the terminal M after the inversion synthesis detected by the inversion synthesis circuit has the same phase as the voltage waveform of the terminal M of the inversion synthesis circuit of the power transmission device 10 shown in FIG. becomes. Here, comparing FIG. 6 and FIG. 11, the drive applied to the switching elements (12a to 12d, 22a to 22d) of the full bridge circuit 12 of the power transmitting device 10 and the full bridge circuit 22 of the power receiving device 20 It can be seen that the voltage has an inverted phase with a phase shift of 180 degrees. As described above, in the contactless power transmission device according to the present embodiment, in the power transmitting device and the power receiving device, the full bridge circuit is configured with opposite polarities with respect to the resonance waveform generated by the coupling of the resonance systems of the two. It can be seen that by switching Hi/Lo of the two switching elements, power transmission can be performed with higher efficiency.

b. Rectification Suspended Operation and Power Transmission Operation FIG. 12 is a circuit configuration diagram of the power receiving device according to the present embodiment for explaining the flow of current that suspends the rectification operation of power transmitted from the power transmitting device. .

FIG. 13 is a timing chart for explaining the operation of stopping the rectification of the current received by the power receiving resonance system in the power receiving device according to the present embodiment.

For example, when the power source 21 of the power receiving device 20 is a secondary battery and the power received by the power receiving resonance system 13 is used to charge the secondary battery, the charging capacity of the secondary battery increases and the power receiving resonance system 23 As the power to be taken out becomes smaller, the resonance voltage of the resonance coil 23a and the resonance capacitor 23b of the power receiving resonance system 23 increases. In this case, it is necessary to suspend the rectification from the power receiving resonance system 23 to the power supply 21 side.

In such a case, as shown in FIG. 13, the drive control circuit 24 controls the operation so that the gate terminals B and D are set to Hi and the gate terminals A and C are set to Lo. In 22, the switching element b and the switching element d arranged on the ground 26 side are controlled to be ON, and the switching element a and the switching element c arranged on the power supply 21 side are controlled to be OFF.

By doing so, the resonance current H flows only between the ground-side elements of the full bridge circuit 22 and the power receiving resonance system 23, as indicated by arrows a and c in FIG. In the transmitting/receiving apparatus of this embodiment, the resonance current detection circuit 25 detects the current I and the current J flowing through the two elements on the ground side of the full bridge circuit 22. Therefore, arrows a and c shown in FIG. can be grasped as a resonance current I and a resonance current J shown in FIG.

At this time, in the power receiving device 20 according to the present embodiment, the current I flowing through the first resistor 25a is inverted and combined with the current J flowing through the second resistor 25b. Although the voltage value at M is double the voltage value during normal power reception or synchronous rectification, the phase, that is, the timing at which the resonance current becomes 0, is the same. Therefore, when power reception is resumed from a pause (shutdown) state, ON/OFF control of each switching element of the full bridge circuit 22 is paused (shutdown) in accordance with the timing of the resonance current detected by the resonance current detection circuit 25 . ) can be immediately resumed at the operation timing before the state.

In the case where the current value flowing through the switching element on the power supply side constituting the full bridge circuit is detected by the detection circuit, the terminals A and C of the drive control circuit are set to Hi, and the terminals B and D are set to Hi. By controlling the resonance current H of the power receiving resonance system to flow through the power supply side of the full bridge circuit 22 as Lo, the resonance current waveform in the resting (cutting off) state can be continuously grasped, and immediately from the resting (cutting off) state. The ability to return to the power receiving state is the same as in the case of the power transmission device described above.

FIG. 14 is a timing chart when the power receiving device according to the present embodiment operates in a power transmission mode in which power remaining in the power receiving resonance system is transmitted to the power transmission device side after entering the sleep (shutdown) state. show.

As described above, the power transmitting device described in this embodiment may use a secondary battery for the power source 11. In this case, after power transmission from the power transmitting device stops, the power receiving resonance system of the power receiving device By transmitting the remaining power to the power transmission device, the power of the secondary battery that constitutes the power source 11 of the power transmission device can be recovered.

As shown in FIG. 14, in the resting (shutdown) state, the terminal voltages B and D are set to Hi and the terminal voltage A is set to ON so that only the two switching elements 12b and 12d on the side of the ground 26 are turned on in the full bridge circuit 12. After that, when the resonance current is "positive", the terminal voltages A and D are set to Hi, the terminal voltages B and C are set to Lo, and when the resonance current is "negative", the terminal voltages B and C is set to Hi, and the terminal voltages A and D are set to Lo, the power receiving device can be operated as a power transmitting device, and power can be transmitted from the power receiving device side to the power transmitting device side.

As in the case of the power transmitting device described with reference to FIG. 9, in the power receiving device according to the present embodiment, the currents flowing through the two switching elements in the lower stage of the full bridge circuit are inversely combined to produce the output of the resonance current detection circuit. Therefore, as shown in FIG. 14, even in the power transmission mode of the power receiving device, the detected waveform of the resonance voltage is the same as in the synchronous rectification operation in the power reception mode or in the pause (shutdown) mode. Therefore, in the power receiving device according to the present embodiment, it is possible to smoothly switch among the power receiving mode, the pause (shutdown) mode, and the power transmission mode.

The control state of the operating voltage pulse from the drive control circuit 24 to each switching element of the full bridge circuit 22 in the power transmission mode in this power receiving device is the same as the operation control of the full bridge circuit 12 in the power transmitting device 10 described above. becomes.

As described above, in the power receiving device described in this embodiment, when used as a power transmitting device, the body diodes of the switching elements of the full bridge circuit that control the current flow to the power transmitting resonant system are used to control the power receiving resonant system. can be converted into direct current by full-wave rectification.

Furthermore, by controlling the ON/OFF of the switching elements that make up the full bridge circuit according to the phase of the resonance current of the power receiving resonance system, it is possible to perform synchronous rectification that can avoid voltage drops due to the body diodes of the switching elements. , it is possible to achieve power reception with high power reception efficiency.

In addition, by detecting the current flowing through the two switching elements on the ground side of the switching element of the full-bridge circuit by the resonance current detection circuit, control in the pause (shutdown) mode that suspends (shuts off) the power receiving operation. A configuration in which control in a power transmission mode in which power is transmitted from a device to the power transmission device side is controlled based on a continuous resonance voltage waveform of the same phase can be realized at low cost.

[Use as a two-way power transmission/reception device]
As described above, in the contactless power transmission device described in this embodiment, a device having the same configuration can be used as both a power transmitting device and a power receiving device. Power transmission can be performed.

For example, as shown in FIG. 15, two contactless power transmission devices 41 and 42 are used to connect a storage battery 43 that stores power generated by a solar panel 45 installed in a home, for example, to an electric vehicle. Electric power can be transmitted to the secondary battery 44 . On the other hand, when power transmission from the electric power company is stopped due to a disaster such as an earthquake, power is transmitted from the device 42 to the device 41 in the opposite direction to the charging direction of the secondary battery 44 mounted on the vehicle. Therefore, the electric power stored in the secondary battery 44 of the automobile can be utilized as a power source for operating electric devices in the home together with the electric power supplied from the solar panel 45 .

In addition, the contactless power transmission described in the present embodiment can also be performed as a form using power transmission between three or more contactless power transmission devices instead of transmitting power between two contactless power devices. Transmission equipment is available. For example, by adopting the contactless power transmission device disclosed in the present application as a power transmission device mounted on a submarine, a helicopter, etc., the base operates as a power receiving device that receives power from another contactless power transmission device, and then , can be used as a power transmission device that transmits power to a power receiving device connected to the operating power source of equipment in hard-to-reach places such as the seabed or mountain tops.

In the above embodiments, the contactless power transmission device disclosed in the present application has been described as a bidirectional contactless power transmission device that may be used as a power transmitting device and as a power receiving device.

However, the configuration including the power supply, the full bridge circuit, the resonance system, the drive control circuit, and the resonance current detection circuit described in the present embodiment can be used as a power transmitting device alone and a power receiving device alone. It is possible to perform various operational controls of the above.

Therefore, the contactless power transmission device disclosed in the present application is suitable not only as a power transmission device capable of bidirectionally transmitting power, but also as a power transmission device that only transmits power, or as a power reception device that only receives power. can be used.

Further, in the above embodiment, the power transmission device performs all the operation controls performed by the drive control circuit, including self-oscillation control, control for increasing or decreasing resonance current, PWM control, pause (shutoff) control, and recovery control. Although exemplified, when the contactless power transmission device disclosed in the present application is used as a power transmission device, it is not necessary to perform all of these controls. Needless to say, it can be realized as a power transmission device that performs only part of the various controls described above.

Similarly, when the contactless power transmission device disclosed in the present application is used as a power receiving device, all of the above-described synchronous rectification control, pause (shutdown) control, and transmission control from the power receiving device are performed. is not limited, and it can be realized as a power receiving device that performs only a part of these operation controls.

In the above embodiments, the full bridge circuit using MOSFETs as switching elements has been exemplified and explained as an example of the switching circuit. As the switching circuit, various elements conventionally used as switching elements in power supply circuits, such as other transistor elements and IGBTs, can be used in addition to the MOSFET described above.

In the contactless power transmission device disclosed in the present application, it is preferable to use an element having a body diode, such as a MOSFET, because it is necessary for the power receiving device to rectify the received current. For example, when using a switching element that does not have a body diode, such as an IGBT, a diode is additionally arranged in parallel with the switching element so that current flows only in the direction from the ground side to the power supply side. In addition, including the case where a MOSFET is used as a switching element, when the resistance component of the body diode is large, connecting a diode with a smaller resistance component in parallel with the switching element will reduce the power consumption of the device. is preferred.

Further, the switching circuit is not limited to the full bridge circuit illustrated above, and a half bridge circuit can also be used. However, in a contactless power transmission device equipped with a half-bridge circuit, when used as a power transmission device, for example, self-excited oscillation operation can be handled as it is, but when PWM control is performed, it is detected by the resonance current detection circuit. Since the resonance current for the remaining half cycle is obtained only for half the cycle, it may be necessary to perform signal processing such as creating the resonance current waveform for the remaining half cycle by inversion synthesis. Further, when used as a power receiving device, the rectification of the received current is half-wave rectification, so the power receiving efficiency is lower than when full-wave rectification is performed using a full bridge circuit as a switching circuit.

The circuit configuration of the switching circuit composed of a plurality of switching elements is not limited to the so-called bridge connection configuration such as the full bridge circuit and the half bridge circuit described above. Other circuit configurations can be employed as long as they can change the direction of the current applied to the system and can rectify the resonance current when used as a power receiving device.

Furthermore, when using a pair of power transmission devices of the present invention as a power transmission device and the other as a power reception device, when the power switch of the power transmission device is attached and power transmission is started by turning on the switch, if the interruption operation continues, the other party It is also possible to determine that the battery on the side is fully charged, stop the power transmission operation, and turn off the power switch.

This is because when the power receiving device is fully charged and no more power is required, the cutoff mode is set, and the transmitted power from the power transmission side has no place to go, and the resonance voltage on the power transmission side rises, causing the cutoff mode to continue. In this case, it is appropriate to turn off the power switch, and this series of operations makes it possible to control power transmission and reception by the configuration of the present invention without performing power transmission and reception control by communication. This has the advantage that the power transmitting/receiving device can be configured with a simple configuration. Of course, bi-directional power transmission is possible, so by transmitting power to another power receiving device using a charged device as a power transmission device, the present invention can be configured and used as a device capable of exchanging power. Needless to say.

The power transmission device of the present disclosure can be used as a power transmission and reception device that can transmit power in both directions and can be used as both a power transmission device and a power reception device, or as a power transmission device that only transmits power and a power reception device that only receives power. It is useful as a non-contact power transmission device capable of highly efficient and highly safe power transmission despite its structure.

10 power transmission device 11 power supply 12 full bridge circuit (switching circuit)
13 power transmission resonance system (resonance system)
14 drive control circuit 15 resonance current detection circuit 100 detection circuit 20 power receiving device 21 power supply 22 full bridge circuit (switching circuit)
23 power receiving resonance system (resonance system)
24 drive control circuit 25 resonance current detection circuit 200 detection circuit

Claims (7)

A power transmission device capable of contactless bidirectional power transmission,
a rechargeable power source;
a switching circuit comprising a plurality of switching elements;
a resonant system comprising a coil and a capacitor;
a drive control circuit for controlling the ON/OFF operation of each switching element that constitutes the switching circuit;
The power transmission device is used as both a power transmission device and a power reception device,
At least one selected from the group consisting of an excessive resonance voltage of the coil, an excessive resonance current of the coil, a temperature in the power transmission device, an excessive current during power supply to the power source, and an excessive voltage of the power source. Detecting a predetermined condition, and based on the detection result of the predetermined condition,
The drive control circuit performs control to turn ON only the switching element on either the power supply side or the ground side of each switching element constituting the switching circuit,
Furthermore, a current detection circuit is provided between the power supply and the switching circuit,
detecting an excessive current during power supply to the power supply based on the current value detected by the current detection circuit;
Based on the detection result of an excessive current during power supply to the power supply, the drive control circuit performs control to turn ON only the switching element on either the power supply side or the ground side of each switching element constituting the switching circuit. contactless power transmission device. A power transmission device capable of contactless bidirectional power transmission,
a rechargeable power source;
a switching circuit comprising a plurality of switching elements;
a resonant system comprising a coil and a capacitor;
a drive control circuit for controlling the ON/OFF operation of each switching element that constitutes the switching circuit;
The power transmission device is used as both a power transmission device and a power reception device,
At least one selected from the group consisting of an excessive resonance voltage of the coil, an excessive resonance current of the coil, a temperature in the power transmission device, an excessive current during power supply to the power source, and an excessive voltage of the power source. Detecting a predetermined condition, and based on the detection result of the predetermined condition,
The drive control circuit performs control to turn ON only the switching element on either the power supply side or the ground side of each switching element constituting the switching circuit,
Furthermore, it has a power supply voltage detection circuit,
detecting excessive voltage of the power supply based on the voltage detected by the voltage detection circuit;
Non-contact power in which the drive control circuit turns ON only the switching element on either the power supply side or the ground side of each switching element constituting the switching circuit based on the detection result of the overvoltage of the power supply. transmission equipment. A power transmission device capable of contactless bidirectional power transmission,
a rechargeable power source;
a switching circuit comprising a plurality of switching elements;
a resonant system comprising a coil and a capacitor;
a drive control circuit for controlling the ON/OFF operation of each switching element that constitutes the switching circuit;
The power transmission device is used as both a power transmission device and a power reception device,
At least one selected from the group consisting of an excessive resonance voltage of the coil, an excessive resonance current of the coil, a temperature in the power transmission device, an excessive current during power supply to the power source, and an excessive voltage of the power source. Detecting a predetermined condition, and based on the detection result of the predetermined condition,
The drive control circuit performs control to turn ON only the switching element on either the power supply side or the ground side of each switching element constituting the switching circuit,
Furthermore, a current detection circuit is provided between the switching circuit and the ground,
detecting an excessive current of the power supply based on the current value detected by the current detection circuit;
Non-contact power in which the drive control circuit turns ON only the switching element on either the power supply side or the ground side of each switching element constituting the switching circuit based on the detection result of the excessive current of the power supply. transmission equipment. The contactless power transmission device according to any one of claims 1 to 3 ,
and a resonance voltage detection circuit for the capacitor ,
detecting an excessive voltage of the resonance voltage of the capacitor based on the resonance voltage detected by the resonance voltage detection circuit;
The contactless power transmission device according to claim 1, wherein the drive control circuit turns ON only the switching element on either the power supply side or the ground side of each switching element constituting the switching circuit based on the detection result of the overvoltage. The contactless power transmission device according to any one of claims 1 to 3 ,
further comprising a resonance current detection circuit that detects a resonance current flowing through the switching circuit,
detecting an excessive resonance current of the coil based on the resonance current value detected by the resonance current detection circuit;
The contactless power transmission device according to claim 1, wherein the drive control circuit turns ON only the switching element on either the power supply side or the ground side of each switching element constituting the switching circuit based on the detection result of the excessive current. The contactless power transmission device according to any one of claims 1 to 3 ,
further comprising a temperature detection circuit that detects the temperature of the power transmission device,
detecting excessive or insufficient temperature of the power transmission device based on the temperature detected by the temperature detection circuit;
Based on the detection result of the excessive temperature or the insufficient temperature, the drive control circuit performs control to turn ON only the switching element on either the power supply side or the ground side of each switching element constituting the switching circuit. Contact power transmission device. The contactless power transmission device according to any one of claims 1 to 6 ,
The drive control circuit performs control to turn ON only the switching element on either the power supply side or the ground side of each switching element constituting the switching circuit,
A non-contact power transmission device in which the power of the non-contact power transmission device is turned off after the ON control continues for a predetermined period.

Images