JP2015159668A - Power transmission equipment and non-contact power transmission device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide power transmission equipment and a non-contact power transmission device capable of suppressing excessive exothermic of a switching element.SOLUTION: Power transmission equipment 11 includes: an AC power supply 12 which includes a DC/AC converter 12c for converting DC power into AC power; and a primary side coil 13a to which the AC power is input. The DC/AC converter 12c includes a bridge circuit 12cc having a first switching element Q1 and a second switching element Q2 mutually connected in series, and a third switching element Q3 and a fourth switching element Q4 mutually connected in series. The operation mode of each switching element Q1-Q4 is switched from a first half-bridge mode to a second half-bridge mode, when a changeover condition is satisfied in a state of the first half-bridge mode.

Description

  The present invention relates to a power transmission device and a contactless power transmission device.

  As a non-contact power transmission device that does not use a power cord or a power transmission cable, for example, an AC power source that outputs AC power of a predetermined frequency, and a power transmission device that has a primary coil to which the AC power is input, What is provided with the power receiving apparatus which has the secondary side coil which can receive alternating current electric power from a primary side coil non-contacting is known (for example, refer patent document 1). In such a non-contact power transmission device, AC power is transmitted from a power transmitting device to a power receiving device in a non-contact manner, for example, by magnetic resonance between the primary side coil and the secondary side coil. In Patent Document 1, a power receiving device is mounted on a vehicle, and AC power received by the power receiving device is used for charging a power storage device mounted on the vehicle.

JP 2009-106136 A

  The AC power source includes, for example, a DC / AC conversion unit that converts DC power into the AC power. The DC / AC conversion unit includes, for example, a switching element, and performs power conversion by the ON / OFF operation of the switching element periodically.

  Here, when the switching element periodically performs ON / OFF operation, the switching element may generate heat due to a switching loss or the like. In this case, there is a concern about a decrease in conversion efficiency of the DC / AC converter.

  The objective of this invention is made | formed in view of the situation mentioned above, and is providing the power transmission apparatus and non-contact electric power transmission apparatus which can suppress the excessive heat_generation | fever of a switching element.

  A power transmission device that achieves the above object includes an AC power source having a DC / AC conversion unit that converts DC power into AC power having a predetermined frequency, and a primary coil to which the AC power is input, The AC power can be transmitted from the primary coil to the secondary coil of a power receiving device having a secondary coil in a non-contact manner, and the DC / AC converters are connected in series to each other. A bridge circuit having a first switching element and a second switching element, and a third switching element and a fourth switching element connected in series with each other, and one end of the primary coil is connected to the first switching element and the first switching element. The other end of the primary side coil is connected to the connection line between the third switching element and the fourth switching element, The operation mode of each switching element is such that the first switching element and the second switching element are alternately turned ON / OFF, while the third switching element is in an OFF state and the fourth switching element is ON. The first half-bridge mode, which is in a state, and the third switching element and the fourth switching element alternately perform ON / OFF operations, while the first switching element is in the OFF state, and the second switching element And the second half-bridge mode in which the switching element is in an ON state, and the operation mode of each switching element is the first half-bridge mode when a predetermined switching condition is satisfied in the situation of the first half-bridge mode. Switching from the half bridge mode to the second half bridge mode

  According to this configuration, when the switching condition is satisfied, the operation mode of each switching element is switched from the first half bridge mode to the second half bridge mode. Since the first switching element and the second switching element are alternately turned ON / OFF in the first half-bridge mode, they easily generate heat. On the other hand, since the first switching element and the second switching element are in the ON state or the OFF state in the second half bridge mode, they are unlikely to generate heat. Thereby, the excessive heat_generation | fever of a 1st switching element and a 2nd switching element can be suppressed by switching of the said operation mode.

  About the said power transmission apparatus, the said switching conditions are good to include that the period when the operation mode of each said switching element is a said 1st half bridge mode becomes more than a predetermined threshold period. According to such a configuration, it is possible to suppress the first switching element and the second switching element from excessively generating heat due to the first half-bridge mode being continued for a long time.

  Regarding the power transmission device, the operation mode of each switching element is OFF, in which the first switching element and the third switching element are in an OFF state, and the second switching element and the fourth switching element are in an ON state. The operation mode of each of the switching elements including the mode may be switched from the first half bridge mode to the second half bridge mode via the OFF mode when the switching condition is satisfied. When switching directly from the first half-bridge mode to the second half-bridge mode, depending on the state of each switching element, an excessive reverse voltage is applied to at least a part of each switching element, resulting in an increase in loss, etc. Inconvenience can occur. On the other hand, according to the present configuration, the operation mode of each switching element is switched from the first half bridge mode to the second half bridge mode via the OFF mode.

  As a specific aspect of this configuration, for example, “the operation mode of each switching element is switched from the first half-bridge mode to the OFF mode when the switching condition is satisfied, and then the OFF mode. To the second half-bridge mode ”.

  In the power transmission device, the operation mode of each switching element is such that the switching element group of the first switching element and the fourth switching element and the switching element group of the second switching element and the third switching element are alternately turned ON / OFF. It is desirable to include a full bridge mode that operates OFF. According to this configuration, by using the full bridge mode as the operation mode of each switching element, it is possible to output AC power having a large power value compared to the case where the half bridge mode is used. Thereby, it is possible to suitably output a large AC power having a relatively large power value and a small AC power having a relatively small power value from the AC power source.

  Here, for example, it is conceivable that a DC / DC converter or the like is provided in the AC power source and both the large AC power and the small AC power are output using the DC / DC converter. However, when the power value of the large AC power and the power value of the small AC power are greatly different, one AC power cannot be output or the voltage waveform or current waveform of the one AC power is distorted. Inconvenience that may occur may occur.

  On the other hand, according to this configuration, when the large AC power is output, the full bridge mode is used, and when the small AC power is output, the half bridge mode is used. Both AC power and small AC power can be suitably output.

  For the power transmission device, the first control signal and the second control signal are input, and depending on the signal mode of the first control signal and the second control signal, the operation mode of each switching element, A switching circuit for switching to one of the first half bridge mode, the second half bridge mode, and the full bridge mode may be provided. According to this configuration, the operation mode of each switching element can be switched by controlling each control signal. Thereby, control of the operation mode of each switching element can be facilitated.

  A non-contact power transmission device that achieves the above object includes an AC power source having a DC / AC converter that converts DC power into AC power having a predetermined frequency, a primary coil to which the AC power is input, A secondary coil capable of receiving the AC power input to the primary coil in a non-contact manner, and the DC / AC converter includes a first switching element and a second switching element connected in series to each other. And a bridge circuit having a third switching element and a fourth switching element connected in series to each other, and one end of the primary coil is connected to the first switching element and the second switching element. The other end of the primary coil is connected to a connection line between the third switching element and the fourth switching element, and the movement of each switching element is In the first mode, the first switching element and the second switching element are alternately turned ON / OFF, the third switching element is in the OFF state, and the fourth switching element is in the ON state. The half-bridge mode, the third switching element, and the fourth switching element alternately perform ON / OFF operations, while the first switching element is in an OFF state and the second switching element is in an ON state. A switching condition that is predetermined in a situation where the operation mode of each of the switching elements is the first half bridge mode. If it is established, the operation mode of each of the switching elements is changed to the first half bridge. Characterized in that the mode includes a control unit for switching to the second half-bridge mode.

  According to this configuration, when the switching condition is satisfied, the operation mode of each switching element is switched from the first half bridge mode to the second half bridge mode. Since the first switching element and the second switching element are alternately turned ON / OFF in the first half-bridge mode, they easily generate heat. On the other hand, since the first switching element and the second switching element are in the ON state or the OFF state in the second half bridge mode, they are unlikely to generate heat. Thereby, the excessive heat_generation | fever of a 1st switching element and a 2nd switching element can be suppressed by switching of the said operation mode.

  According to this invention, excessive heat generation of the switching element can be suppressed.

The circuit diagram which shows the outline | summary of a power transmission apparatus and a non-contact electric power transmission apparatus. The circuit diagram which shows a switching circuit. Explanatory drawing which shows the relationship between each control signal and the operation mode of each switching element. The flowchart which shows the power transmission start process performed with the power transmission side controller. The flowchart which shows the half bridge mode switching process performed in the power transmission side controller. The graph which shows typically the temperature change of a 1st switching element and a 2nd switching element.

Hereinafter, an embodiment of a power transmission device (power transmission device) and a non-contact power transmission device (non-contact power transmission system) will be described.
As shown in FIG. 1, the non-contact power transmission device 10 includes a power transmission device 11 (ground side device, primary side device) and a power receiving device 21 (vehicle side device, secondary side device) capable of non-contact power transmission. It has. The power transmission device 11 is provided on the ground, and the power receiving device 21 is mounted on the vehicle.

  The power transmission device 11 includes an AC power supply 12 that can output AC power having a predetermined frequency. The AC power supply 12 is configured to be able to convert the system power to AC power and output the converted AC power when the system power is input from the system power supply E as infrastructure.

  Specifically, the AC power supply 12 serves as an AC / DC converter, a rectifier 12a that rectifies system power input from the system power supply E into DC power, and DC that performs voltage value conversion of the DC power rectified by the rectifier 12a. / DC converter 12b. The AC power supply 12 includes a DC / AC converter 12c that converts DC power output from the DC / DC converter 12b into AC power.

  The DC / AC converter 12c has a bridge circuit 12cc having a plurality of switching elements Q1 to Q4. Each switching element Q1-Q4 is comprised, for example by n-type power MOSFET. The drain of the first switching element Q1 is connected to the positive (+) output terminal of the DC / DC converter 12b, and the source of the second switching element Q2 is the negative (−) output terminal of the DC / DC converter 12b. It is connected to the. The first switching element Q1 and the second switching element Q2 are connected in series with each other. Specifically, the source of the first switching element Q1 and the drain of the second switching element Q2 are connected via the connection line L1. ing.

  Similarly, the drain of the third switching element Q3 is connected to the positive (+) output terminal of the DC / DC converter 12b, and the source of the fourth switching element Q4 is the negative (−) of the DC / DC converter 12b. Is connected to the output end of. The third switching element Q3 and the fourth switching element Q4 are connected in series with each other. Specifically, the source of the third switching element Q3 and the drain of the fourth switching element Q4 are connected via the connection line L2. ing.

  One input end of the power transmitter 13 (one end of the primary coil 13a) is connected to the connection line L1 between the first switching element Q1 and the second switching element Q2, and the other input of the power transmitter 13 is connected. The end (the other end of the primary coil 13a) is connected to a connection line L2 between the third switching element Q3 and the fourth switching element Q4.

  Incidentally, the DC / DC converter 12b is a step-up type having a switching element 12bb, and performs voltage value conversion by the ON / OFF operation of the switching element 12bb periodically. In this case, the voltage value of the DC power output from the DC / DC converter 12b depends on the duty ratio of the ON / OFF operation of the switching element 12bb. The power value of the AC power output from the AC power supply 12 (specifically, the DC / AC converter 12c) depends on the voltage value converted by the DC / DC converter 12b. That is, the duty ratio (pulse width) of the ON / OFF operation of the switching element 12bb is one parameter that defines the power value of the AC power output from the AC power supply 12.

  The AC power output from the AC power supply 12 is transmitted to the power receiving device 21 in a non-contact manner, and is input to the load 22 provided in the power receiving device 21. Specifically, the non-contact power transmission apparatus 10 performs power transmission between the power transmission device 11 and the power reception device 21, and includes a power transmitter 13 provided in the power transmission device 11 and a power receiver provided in the power reception device 21. 23.

  The power transmitter 13 and the power receiver 23 have the same configuration, and both are configured to be capable of magnetic field resonance. Specifically, the power transmitter 13 has a resonance circuit including a primary side coil 13a and a primary side capacitor 13b connected in parallel to each other. The power receiver 23 has a resonance circuit including a secondary coil 23a and a secondary capacitor 23b connected in parallel to each other. The resonant frequencies of both resonant circuits are set to be the same.

  According to such a configuration, when AC power is input to the power transmitter 13 (primary coil 13a) in a situation where the relative position between the power transmitter 13 and the power receiver 23 is in a position where magnetic resonance can occur, The power receiver 23 (secondary coil 23a) performs magnetic field resonance. As a result, the power receiver 23 receives part of the energy from the power transmitter 13. That is, the power receiver 23 receives AC power from the power transmitter 13.

  Incidentally, the frequency of the AC power output from the AC power supply 12 is set corresponding to the resonance frequency of the power transmitter 13 and the power receiver 23 so that power transmission is possible between the power transmitter 13 and the power receiver 23. Yes. For example, the frequency of AC power is set to be the same as the resonance frequency of the power transmitter 13 and the power receiver 23. However, the present invention is not limited thereto, and the frequency of the AC power and the resonance frequency of the power transmitter 13 and the power receiver 23 may be deviated within a range where power transmission is possible.

  The load 22 to which the AC power received by the power receiver 23 is input includes, for example, an AC / DC converter (rectifier) that converts the AC power into DC power, and DC power converted by the AC / DC converter. And an input vehicle battery (power storage device). As a result, the vehicle battery is charged using the AC power received by the power receiver 23.

  The power transmission device 11 includes a power transmission side controller 14 that controls the AC power source 12 and the like. Specifically, the power transmission side controller 14 variably controls the duty ratio of the ON / OFF operation of the switching element 12bb, and is a circuit provided in the power transmission device 11 (specifically, the DC / AC converter 12c). And the switching circuit 30 which switches the operation mode of each switching element Q1-Q4 is controlled. In the present embodiment, the power transmission side controller 14 corresponds to a “control unit”.

  The power receiving device 21 includes a power receiving side controller 24 that can wirelessly communicate with the power transmitting side controller 14. The controllers 14 and 24 start or end power transmission through the exchange of information with each other.

Next, the detailed configuration of the switching circuit 30 will be described together with the operation modes of the switching elements Q1 to Q4.
As shown in FIGS. 1 and 2, the switching circuit 30 is connected to the gates of the switching elements Q1 to Q4, and operates the switching elements Q1 to Q4 individually. Specifically, the switching circuit 30 operates the switching elements Q1 to Q4 in any one of the operation modes of the OFF mode, the first half bridge mode, the second half bridge mode, or the full bridge mode. In other words, the operation modes of the switching elements Q1 to Q4 include an OFF mode, a first half bridge mode, a second half bridge mode, and a full bridge mode, and the switching circuit 30 includes the switching elements Q1 to Q4. The operation mode is switched to one of the four operation modes.

  Each operation mode will be described in detail. The OFF mode is an operation mode in which the first switching element Q1 and the third switching element Q3 are in the OFF state, and the second switching element Q2 and the fourth switching element Q4 are in the ON state. is there. In this case, AC power is not input to the power transmitter 13.

  In the first half-bridge mode, the first switching element Q1 and the second switching element Q2 are alternately turned ON / OFF, while the third switching element Q3 is OFF and the fourth switching element Q4 is ON. It is an operation mode that is a state.

  In the second half-bridge mode, the third switching element Q3 and the fourth switching element Q4 are alternately turned ON / OFF, while the first switching element Q1 is in the OFF state and the second switching element Q2 is ON. It is an operation mode that is a state.

  The full bridge mode is an operation mode in which the switching element group of the first switching element Q1 and the fourth switching element Q4 and the switching element group of the second switching element Q2 and the third switching element Q3 are alternately turned ON / OFF. is there. Specifically, as the states of the switching elements Q1 to Q4, the first switching element Q1 and the fourth switching element Q4 are in the ON state, and the second switching element Q2 and the third switching element Q3 are in the OFF state. Is in the first state. As the states of the switching elements Q1 to Q4, the first switching element Q1 and the fourth switching element Q4 are in the OFF state, and the second switching element Q2 and the third switching element Q3 are in the ON state. Two states are assumed. In this case, the full bridge mode is an operation mode in which the states of the switching elements Q1 to Q4 are alternately switched between the first state and the second state.

  Here, each switching element Q1-Q4 has body diode (parasitic diode) D1-D4. A current related to the back electromotive force that can be generated when the operation mode of each switching element Q1 to Q4 is each half bridge mode or full bridge mode is transmitted through each body diode D1 to D4.

  As shown in FIG. 2, the power transmission side controller 14 includes an oscillation circuit 14 a that outputs a pulse signal P having the same frequency as the resonance frequency of the power transmitter 13 and the power receiver 23 or a frequency close to the resonance frequency to the extent that power transmission is possible. I have. The switching circuit 30 is configured to receive the pulse signal P and the two control signals SG1 and SG2 from the power transmission side controller 14, and each switching element according to the signal mode of the control signals SG1 and SG2. The operation mode of Q1 to Q4 is switched to the OFF mode, the first half bridge mode, the second half bridge mode, or the full bridge mode.

  The switching circuit 30 receives the pulse signal P output from the oscillation circuit 14a via the NOT circuit 31 and the first AND circuit 32 to which the first control signal SG1 is input and the output signal of the first AND circuit 32. A first buffer circuit 33 and a first NOT circuit 34 are provided. The output signal of the first buffer circuit 33 is input to the gate of the first switching element Q1, and the output signal of the first NOT circuit 34 is input to the gate of the second switching element Q2.

  The switching circuit 30 receives the pulse signal P output from the oscillation circuit 14a without passing through the NOT circuit 31, and receives the second control signal SG2 and the output of the second AND circuit 35. A second buffer circuit 36 and a second NOT circuit 37 to which signals are input are provided. The output signal of the second buffer circuit 36 is input to the gate of the third switching element Q3, and the output signal of the second NOT circuit 37 is input to the gate of the fourth switching element Q4.

  According to such a configuration, as shown in FIG. 3, when both the first control signal SG1 and the second control signal SG2 are low signals, the operation mode of each of the switching elements Q1 to Q4 is the OFF mode. When the first control signal SG1 is a high signal and the second control signal SG2 is a low signal, the operation mode of each switching element Q1 to Q4 is the first half-bridge mode, and the first control signal SG1 is a low signal. When the second control signal SG2 is a high signal, the operation mode of each of the switching elements Q1 to Q4 is the second half bridge mode. Further, when both of the control signals SG1 and SG2 are high signals, the operation mode of each of the switching elements Q1 to Q4 is a full bridge mode.

Next, AC power output from the AC power supply 12 (DC / AC converter 12c) will be described.
Under the condition that the duty ratio of the ON / OFF operation of the switching element 12bb of the DC / DC converter 12b is the same, the power value of the AC power in the first half bridge mode and the power value of the AC power in the second half bridge mode Are the same.

  Under the condition that the duty ratio of the ON / OFF operation of the switching element 12bb of the DC / DC converter 12b is the same, the voltage value and current value of the AC power in the full bridge mode are the voltage value of the AC power in each half bridge mode and It is twice the current value. That is, the power value of AC power in each half-bridge mode is 1/4 of the power value of AC power in the full-bridge mode.

  That is, the power value of the AC power varies depending on the operation mode of each switching element Q1 to Q4. In other words, the operation mode of each of the switching elements Q1 to Q4 can be said to be one parameter that defines the power value of the AC power.

  The AC power supply 12 can output AC power having different power values by adjusting the duty ratio of the ON / OFF operation of the switching element 12bb of the DC / DC converter 12b and switching the operation mode of each of the switching elements Q1 to Q4. It is configured. Specifically, the AC power supply 12 is configured to be capable of outputting at least a large AC power having a relatively large power value and a small AC power having a relatively small power value. In the large AC power, the duty ratio of the ON / OFF operation of the switching element 12bb of the DC / DC converter 12b is set to the first duty ratio corresponding to the large AC power, and the operation modes of the switching elements Q1 to Q4 are full. AC power in the bridge mode. In the small AC power, the duty ratio of the ON / OFF operation of the switching element 12bb of the DC / DC converter 12b is set to the second duty ratio corresponding to the small AC power, and the operation modes of the switching elements Q1 to Q4 are each AC power when in half-bridge mode.

  In addition, although the use of large alternating current power and small alternating current power is arbitrary, large alternating current power is used for charging the vehicle battery contained in the load 22, for example. For example, in the small AC power, various processes executed in a stage before outputting the large AC power, for example, power transmission is normally performed between the power transmission device 11 (power transmitter 13) and the power reception device 21 (power receiver 23). It is used in the abnormality determination process for determining whether or not the vehicle is aligned. The vehicle alignment process using the small AC power is, for example, the transmission efficiency based on the power value of the received power received by the power receiver 23 in the situation where the small AC power is input to the power transmitter 13. A process for determining whether or not a vehicle has been placed at a position where is equal to or greater than a predetermined threshold, a process for guiding the vehicle to the position, and the like can be considered.

  Incidentally, various specifications (eg, rated power) of the DC / DC converter 12b are set to the power value of the large AC power so that the voltage waveform and current waveform of the large AC power output from the AC power source 12 are not distorted. It is set correspondingly.

  The power transmission side controller 14 controls the operation mode of each switching element Q1-Q4 by controlling each control signal SG1, SG2, and performs ON / OFF control of AC power and power value control of AC power.

  For example, the power transmission side controller 14 sets each control signal SG1, SG2 to a Low signal in the initial state. Thereby, in the initial state, the operation mode of each of the switching elements Q1 to Q4 is the OFF mode, and the AC power is not output from the AC power supply 12.

  In the initial state, the power transmission controller 14 executes a power transmission start process for controlling the AC power supply 12 so that AC power having a desired power value is output from the AC power supply 12 based on the establishment of a predetermined power transmission condition. . The power transmission start process will be described below.

  As shown in FIG. 4, first, in step S101, the power transmission side controller 14 determines whether or not a predetermined high power transmission condition is satisfied. Although the high power transmission conditions are arbitrary, for example, it is determined whether or not power transmission is normally performed between the power transmission device 11 (power transmitter 13) and the power reception device 21 (power receiver 23) using small AC power. In the configuration for performing the processing, there may be a case where it is determined that the power transmission is normally performed.

  When the high power transmission condition is satisfied, the power transmission side controller 14 executes processing for outputting large AC power in Step S102 and Step S103. In detail, the power transmission side controller 14 sets the operation mode of each switching element Q1-Q4 to a full bridge mode in step S102, and turns ON / OFF the switching element 12bb of the DC / DC converter 12b in step S103. The duty ratio of the operation is set to the first duty ratio.

  On the other hand, if the high power transmission condition is not satisfied, the power transmission side controller 14 makes a negative determination in step S101 and proceeds to step S104. In step S104, the power transmission side controller 14 determines whether or not a predetermined low power transmission condition is satisfied. Although the low power transmission conditions are arbitrary, for example, a case where a vehicle alignment process is performed, a case where the vehicle stops, a case where a power transmission request is received from the power receiving side controller 24, and the like can be considered.

  When the low power transmission condition is not satisfied, the power transmission side controller 14 returns to step S101. On the other hand, when the low power transmission condition is satisfied, the small AC power is output in step S105 and step S106. Process to be executed. In detail, the power transmission side controller 14 sets the operation mode of each switching element Q1-Q4 to 1st half bridge mode in step S105, and turns ON switching element 12bb of the DC / DC converter 12b in step S106. The duty ratio of the / OFF operation is set to the second duty ratio.

  The power transmission side controller 14 is a half bridge at a predetermined cycle in a situation where small alternating current power is output from the AC power source 12 (a situation where the operation mode of each switching element Q1 to Q4 is one of the half bridge modes). Executes half-bridge mode switching processing for switching modes. The half-bridge mode switching process will be described in detail below.

As shown in FIG. 5, first, in step S201, the power transmission side controller 14 determines whether or not a predetermined switching condition is satisfied.
The switching condition is, for example, that a predetermined threshold period Tth elapses after the current operation mode is set. Specifically, when the half-bridge mode is switched in the half-bridge mode switching process prior to the half-bridge mode switching process, the switching condition is that after the previous half-bridge mode switch is performed. This is a case where the threshold period Tth has elapsed. In addition, when the switching mode of the switching elements Q1 to Q4 is set to the first half-bridge mode in the power transmission start process and the half-bridge mode has never been switched, the switching condition is the power transmission start This is a case where the threshold period Tth has elapsed since the operation mode of each of the switching elements Q1 to Q4 was set to the first half bridge mode in the processing.

  Note that the threshold period Tth is, for example, the amount of temperature increase per unit time of each switching element Q1, Q2 when the first switching element Q1 and the second switching element Q2 are turned ON / OFF in the cycle of the pulse signal P. It is set based on the allowable temperature (for example, rated temperature) Tx of each switching element Q1, Q2. For example, the threshold period Tth is a time when each switching element Q1, Q2 at a predetermined temperature (for example, room temperature) is turned on / off in the above cycle over the threshold period Tth. The temperature is set based on the amount of temperature increase so that the temperature falls within the allowable temperature Tx.

The power transmission side controller 14 complete | finishes this process as it is, when the switching conditions are not satisfied. Thereby, the current half-bridge mode is continued.
On the other hand, if the switching condition is satisfied, the power transmission side controller 14 proceeds to step S202, and sets the operation mode of each switching element Q1 to Q4 to the OFF mode. Thereafter, in step S203, the power transmission controller 14 determines whether or not the current operation mode is the first half bridge mode.

  When the current half bridge mode is the first half bridge mode, the power transmission side controller 14 sets the operation mode of each of the switching elements Q1 to Q4 to the second half bridge mode in step S204, and performs this processing. Exit. Specifically, the power transmission side controller 14 switches the first control signal SG1 from the High signal to the Low signal, and switches the second control signal SG2 from the Low signal to the High signal.

  On the other hand, when the current half-bridge mode is the second half-bridge mode, the power transmission side controller 14 makes a negative determination in step S203 and proceeds to step S205. And power transmission side controller 14 sets the operation mode of each switching element Q1-Q4 to the 1st half bridge mode in Step S205, and ends this processing. Specifically, the power transmission side controller 14 switches the first control signal SG1 from the Low signal to the High signal, and switches the second control signal SG2 from the High signal to the Low signal.

  That is, in a situation where small AC power is output from the AC power supply 12, the power transmission side controller 14 changes the operation mode of each switching element Q1 to Q4 from the first half bridge mode to the first half bridge mode every time the threshold period Tth elapses. Switch to 2 half-bridge mode.

Next, the operation of this embodiment will be described.
As shown in FIG. 6, in the situation where small alternating current power is output from the alternating current power supply 12, the operation modes of the switching elements Q1 to Q4 are the first half bridge mode and the second half half each time the threshold period Tth elapses. Switch to bridge mode. Thereby, while the output of the small alternating current power from the alternating current power supply 12 is maintained, the temperature of each switching element Q1, Q2 is settled in the range below the allowable temperature Tx. Similarly, the temperatures of the switching elements Q3 and Q4 are within the range of the allowable temperature Tx or less.

According to the embodiment described above in detail, the following effects are obtained.
(1) The power transmission device 11 includes an AC power source 12 having a DC / AC converter 12c that converts DC power into AC power, and a power transmitter 13 (primary coil 13a) to which AC power is input. The DC / AC converter 12c includes a bridge circuit 12cc having a first switching element Q1 and a second switching element Q2 connected in series with each other, and a third switching element Q3 and a fourth switching element Q4 connected in series with each other. It has. The primary coil 13a is connected to the connection line L1 of the first switching element Q1 and the second switching element Q2, and the connection line L2 of the third switching element Q3 and the fourth switching element Q4.

  In such a configuration, the power transmission side controller 14 of the power transmission device 11 operates the switching elements Q1 to Q4 when the switching condition is satisfied in a situation where the operation mode of the switching elements Q1 to Q4 is the first half bridge mode. Switch the mode to the second half-bridge mode. Since the first switching element Q1 and the second switching element Q2 are alternately turned ON / OFF in the first half-bridge mode, they easily generate heat. On the other hand, since the first switching element Q1 and the second switching element Q2 are in the ON state or the OFF state in the second half bridge mode, they are unlikely to generate heat. Thereby, by switching the operation mode from the first half bridge mode to the second half bridge mode, excessive heat generation of the first switching element Q1 and the second switching element Q2 can be suppressed, and the DC / AC converter 12c of the DC / AC converter 12c is thereby controlled. Reduction in conversion efficiency can be suppressed.

  (2) The operation modes of the switching elements Q1 to Q4 are such that the switching element group of the first switching element Q1 and the fourth switching element Q4 and the switching element group of the second switching element Q2 and the third switching element Q3 are alternately Includes full bridge mode with ON / OFF operation. Thereby, large alternating current power can be suitably output from the alternating current power supply 12. FIG.

  Here, when the specifications of the DC / DC converter 12b and the like are set so as to correspond to the large AC power, if the small AC power is output from the AC power supply 12, the voltage waveform or current waveform of the small AC power is distorted. Or the like, or the power value of the small AC power may deviate from a desired value.

  In particular, since the vehicle battery mounted on the vehicle has a large capacity compared to a battery of a mobile phone or the like, the power value of the large AC power can be set to a relatively large value (for example, several kW). On the other hand, the power value of the small AC power used in the alignment process or the like may be about several W. In order to cope with such a wide variable range of the power value, a step-up / step-down type is adopted as the DC / DC converter 12b, and various numerical values (duty ratio, amplitude, etc.) of the DC / DC converter 12b are adjusted. Such inconvenience is likely to occur, and there is a concern that the DC / DC converter 12b may be increased in size and cost.

  On the other hand, under the condition that the power value of the DC power output from the DC / DC converter 12b is constant (the duty ratio of the ON / OFF operation of the switching element 12bb of the DC / DC converter 12b is constant), The power value of the AC power in the half bridge mode is about ¼ of the power value of the AC power in the full bridge mode. For this reason, when outputting small alternating current power, the said inconvenience can be suppressed by using each half bridge mode, and both large alternating current power and small alternating current power can be output suitably. Further, since a small AC power can be output while adopting a step-up type DC / DC converter 12b, the AC power source 12 can be downsized.

  (3) The switching condition is that the period during which the operation mode of each switching element Q1 to Q4 is the first half bridge mode is equal to or longer than a predetermined threshold period Tth. Thereby, it can suppress that the 1st switching element Q1 and the 2nd switching element Q2 generate | occur | produce excessively resulting from a 1st half bridge mode being continued over a long period of time.

  In particular, according to the present embodiment, an excessive temperature rise of each switching element Q1, Q2 can be suppressed without providing a sensor or the like for measuring the temperature of each switching element Q1, Q2. Can be achieved.

  (4) When the switching condition is satisfied in a situation where the operation mode of each switching element Q1 to Q4 is the first half bridge mode, the power transmission side controller 14 changes the operation mode of each switching element Q1 to Q4 via the OFF mode. To switch from the first half-bridge mode to the second half-bridge mode. Specifically, the power transmission side controller 14 once switches the operation mode of each of the switching elements Q1 to Q4 to the OFF mode, and then switches from the OFF mode to the second half bridge mode. Thereby, it is excessive for at least a part of each of the switching elements Q1 to Q4 due to inconvenience that can be caused by directly switching from the first half-bridge mode to the second half-bridge mode, for example, counter electromotive force that can be caused in the power transmitter 13. An increase in loss due to application of a reverse voltage can be suppressed.

  (5) The power transmission device 11 receives the control signals SG1 and SG2, and changes the operation mode of each of the switching elements Q1 to Q4 according to the signal mode of the control signals SG1 and SG2. A switching circuit 30 for switching to one of the half bridge mode, the second half bridge mode, and the full bridge mode is provided. Thereby, the power transmission side controller 14 can control the operation mode of each switching element Q1-Q4 by controlling each control signal SG1, SG2. Therefore, control can be facilitated.

In addition, you may change the said embodiment as follows.
The switching condition is not limited to the threshold period Tth elapses from the timing set in the current half-bridge mode. For example, a temperature sensor or the like that measures the temperature of at least one of the switching elements Q1 and Q2 may be provided, and the switching condition may be that the temperature measured by the temperature sensor is equal to or higher than a predetermined threshold temperature. When measuring the temperature of each of the switching elements Q1, Q2, the switching condition may be that the temperature of any one of the switching elements Q1, Q2 is equal to or higher than the threshold temperature, The temperature of both switching elements Q1 and Q2 may be equal to or higher than the threshold temperature. In short, the switching condition may include a configuration in which the temperature of at least one of the switching elements Q1 and Q2 is equal to or higher than a predetermined threshold temperature.

  Further, instead of the temperature sensor, a current sensor for detecting the current value flowing through each switching element Q1, Q2 may be provided, and the temperature of each switching element Q1, Q2 may be estimated based on the detection result of the current sensor. . Furthermore, the temperature measurement target is not limited to the switching elements Q1 and Q2, but may be the switching elements Q3 and Q4.

  As a switching condition, the temperature of each switching element Q1, Q2 and the threshold period Tth may be combined. For example, when the threshold period Tth has elapsed since the power transmission controller 14 is set to the current half-bridge mode, or when the temperature of at least one of the switching elements Q1 and Q2 is equal to or higher than the threshold temperature, The configuration may be such that the bridge mode is switched.

  The threshold period Tth may be set based on the ambient temperature of the DC / AC converter 12c (respective switching elements Q1 to Q4). For example, the threshold period Tth may be set shorter as the ambient temperature becomes higher.

  The AC power supply 12 is configured to output large AC power in a situation where the operation mode of each switching element Q1 to Q4 is the full bridge mode, but is not limited thereto, and the operation mode of each switching element Q1 to Q4 is The configuration may be such that a large AC power is output in the situation of the half-bridge mode. In this case, the full bridge mode may be omitted. However, if attention is paid to the fact that both large AC power and small AC power can be suitably output, the AC power supply 12 may be configured to output large AC power in the full bridge mode.

  ○ In the half-bridge mode switching process, the power transmission side controller 14 switches the half-bridge mode based on the fact that a predetermined standby period has elapsed since the operation mode of each switching element Q1 to Q4 is set to the OFF mode. The structure which performs this may be sufficient. In this case, the standby period is preferably a period longer than a period (for example, a time constant) required for the voltage value or current value due to the back electromotive force to become a predetermined threshold value. Thereby, since the half-bridge mode is switched in a state where the influence of the counter electromotive force is relatively small, the loss can be further reduced.

In the half bridge mode switching process, the half bridge mode may be switched without going through the OFF mode.
The first half bridge mode is a state in which the third switching element Q3 and the fourth switching element Q4 are alternately turned on and off, and the second half bridge mode is the state in which the first switching element Q1 and the second switching element Q2 are It may be in a state of being alternately turned ON / OFF.

  In the first half bridge mode, the third switching element Q3 may be in the ON state and the fourth switching element Q4 may be in the OFF state. Similarly, in the second half bridge mode, the first switching element Q1 may be in the ON state and the second switching element Q2 may be in the OFF state. In short, in the half-bridge mode, two switching elements connected in series among the four switching elements Q1 to Q4 are alternately turned ON / OFF, while one of the remaining two switching elements is ON. It is preferable that the operation mode is in the state where the other switching element is in the OFF state.

O The power transmission side controller 14 may set not the 1st half bridge mode but 2nd half bridge mode in step S105.
The power transmission controller 14 switches the power value of the AC power output from the AC power supply 12 from the large AC power to the small AC power when the state of charge (SOC) of the vehicle battery is in a predetermined state. You may control as follows.

The DC / DC converter 12b is a step-up type, but is not limited to this and may be a step-up / step-down type.
O The control subject (control part) of the operation mode of each switching element Q1-Q4 is not restricted to the power transmission side controller 14, It is arbitrary. For example, the power receiving side controller 24 determines an operation mode by executing a power transmission start process and a half bridge mode switching process, and transmits information regarding the determined operation mode to the power transmission side controller 14. And the power transmission side controller 14 may be the structure which sets the signal aspect of each control signal SG1, SG2 based on the said information. In addition, a dedicated controller other than the controllers 14 and 24 may execute the processes.

The AC power that can be output from the AC power supply 12 is not limited to two types of large AC power and small AC power, and may be three or more types.
The DC / DC converter 12b may be omitted.

O The rectifier 12a may be omitted. In this case, DC power may be supplied as external power.
The specific circuit configuration of the switching circuit 30 is not limited to that of the embodiment and is arbitrary. Alternatively, the switching circuit 30 may be omitted, and the power transmission side controller 14 may directly operate the switching elements Q1 to Q4.

The AC power supply 12 may be any of a voltage source, a power source, and a current source.
The resonance frequency of the power transmitter 13 and the resonance frequency of the power receiver 23 are set to be the same. However, the present invention is not limited to this, and they may be different within a range where power transmission is possible.

The power transmitter 13 and the power receiver 23 have the same configuration, but are not limited to this, and may have different configurations.
Each capacitor 13b, 23b may be omitted. In this case, magnetic field resonance is performed using the parasitic capacitances of the coils 13a and 23a.

○ The power receiving device 21 may be mounted on any object, and may be mounted on, for example, a robot or an electric wheelchair.
In embodiment, although the primary side coil 13a and the primary side capacitor | condenser 13b were connected in parallel, it is not restricted to this, Both may be connected in series. Similarly, the secondary coil 23a and the secondary capacitor 23b may be connected in series.

In the embodiment, magnetic field resonance is used in order to realize non-contact power transmission. However, the present invention is not limited to this, and electromagnetic induction may be used.
In the embodiment, the AC power received by the power receiver 23 is used for charging the vehicle battery, but is not limited thereto, and may be used for other purposes, for example.

  The power transmitter 13 may include a resonance circuit including a primary side coil 13a and a primary side capacitor 13b, and a primary side coupling coil that is coupled to the resonance circuit by electromagnetic induction. Similarly, the power receiver 23 may include a resonance circuit including a secondary coil 23a and a secondary capacitor 23b, and a secondary coupling coil coupled to the resonance circuit by electromagnetic induction.

Next, a preferable example that can be grasped from the embodiment and another example will be described below.
(B) The switching condition includes that the temperature of at least one of the first switching element and the second switching element is equal to or higher than a predetermined threshold temperature. Power transmission equipment.

  (B) The AC power supply is configured to be able to output a large AC power and a small AC power having relatively large power values, and the operation mode of each switching element is changed from the AC power supply to the small AC power. The power transmission device according to claim 2, wherein the first half-bridge mode and the second half-bridge mode are alternately switched each time the threshold period elapses in a state where the power is output.

  (C) When the operation mode of each switching element is the full bridge mode, the AC power supply outputs a large AC power having a relatively large power value, and the operation mode of each switching element is the above-mentioned The power transmission device according to claim 4, wherein the power transmission device outputs a small AC power having a relatively small power value in any of the half-bridge modes.

  DESCRIPTION OF SYMBOLS 10 ... Non-contact electric power transmission apparatus, 11 ... Power transmission apparatus, 12 ... AC power supply, 12b ... DC / DC converter, 12c ... DC / AC converter, 12cc ... Bridge circuit, 13 ... Power transmission, 13a ... Primary side coil, DESCRIPTION OF SYMBOLS 14 ... Power transmission side controller, 21 ... Power receiving apparatus, 23 ... Power receiver, 23a ... Secondary coil, 24 ... Power receiving side controller, 30 ... Switching circuit, Q1-Q4 ... Switching element, SG1 ... First control signal, SG2 ... Second control signal, L1, L2 ... connection line, Tth ... threshold period.

Claims (6)

An AC power source having a DC / AC conversion unit for converting DC power into AC power having a predetermined frequency;
A primary coil to which the AC power is input;
In a power transmission device capable of transmitting the AC power in a non-contact manner from the primary side coil to the secondary side coil of a power receiving device having a secondary side coil,
The DC / AC converter includes a bridge circuit having a first switching element and a second switching element connected in series with each other, and a third switching element and a fourth switching element connected in series with each other,
One end of the primary side coil is connected to a connection line between the first switching element and the second switching element, and the other end of the primary side coil is connected to the third switching element and the fourth switching element. Connected to the connection line,
The operation mode of each switching element is:
The first half-bridge mode in which the first switching element and the second switching element alternately perform ON / OFF operations, the third switching element is in an OFF state, and the fourth switching element is in an ON state. When,
The second half-bridge mode in which the third switching element and the fourth switching element alternately perform ON / OFF operations, the first switching element is in an OFF state, and the second switching element is in an ON state. When,
Including
The operation mode of each of the switching elements is switched from the first half bridge mode to the second half bridge mode when a predetermined switching condition is satisfied in the situation of the first half bridge mode. Power transmission equipment.   2. The power transmission device according to claim 1, wherein the switching condition includes a period in which an operation mode of each switching element is the first half bridge mode being equal to or longer than a predetermined threshold period. The operation mode of each switching element includes an OFF mode in which the first switching element and the third switching element are in an OFF state, and the second switching element and the fourth switching element are in an ON state,
The operation mode of each of the switching elements is switched from the first half bridge mode to the second half bridge mode via the OFF mode when the switching condition is satisfied. Power transmission equipment.   The operation mode of each switching element is a full bridge in which the switching element group of the first switching element and the fourth switching element and the switching element group of the second switching element and the third switching element are alternately turned ON / OFF. The power transmission device according to any one of claims 1 to 3, including a mode.   A first control signal and a second control signal are input, and an operation mode of each switching element is set according to a signal mode of the first control signal and the second control signal. The power transmission device according to claim 4, further comprising a switching circuit that switches to any one of a mode, the second half-bridge mode, and the full-bridge mode. An AC power source having a DC / AC conversion unit for converting DC power into AC power having a predetermined frequency;
A primary coil to which the AC power is input;
A secondary coil capable of receiving the AC power input to the primary coil in a contactless manner;
With
The DC / AC converter includes a bridge circuit having a first switching element and a second switching element connected in series with each other, and a third switching element and a fourth switching element connected in series with each other,
One end of the primary side coil is connected to a connection line between the first switching element and the second switching element, and the other end of the primary side coil is connected to the third switching element and the fourth switching element. Connected to the connection line,
The operation mode of each switching element is:
The first half-bridge mode in which the first switching element and the second switching element alternately perform ON / OFF operations, the third switching element is in an OFF state, and the fourth switching element is in an ON state. When,
The second half-bridge mode in which the third switching element and the fourth switching element alternately perform ON / OFF operations, the first switching element is in an OFF state, and the second switching element is in an ON state. When,
Including
When the operation mode of each of the switching elements is controlled and a predetermined switching condition is satisfied in a situation where the operation mode of each of the switching elements is the first half bridge mode, the switching elements A non-contact power transmission apparatus comprising: a control unit that switches the operation mode from the first half bridge mode to the second half bridge mode.