JP2021175286A - Contactless charging system - Google Patents

Abstract

To provide a contactless charging system capable of increasing charging efficiency by adjusting a position of a relay coil to suppress fluctuations in transmission coil current and relay coil current even when a battery voltage fluctuates.SOLUTION: The contactless charging system includes a relay device that relays transmission of electric power, a drive device that can move a position of a relay coil, and a battery sensor that can detect battery current and battery voltage. The drive device is configured to move the relay coil away farther from a transmission coil as a battery admittance value obtained by dividing the battery current by the battery voltage becomes smaller by receiving information on the battery current and battery voltage from the battery sensor.SELECTED DRAWING: Figure 1

Description

The present invention relates to a non-contact charging system capable of non-contact charging of electric power.

As a method for charging electric power in a non-contact manner, a magnetic field resonance method using the magnetic field resonance of the resonance circuit of the power transmission device and the resonance circuit of the power receiving device is known. Compared to the electromagnetic induction method, the magnetic field resonance method is less affected by the coupling coefficient between the coil of the power transmission device (hereinafter, also referred to as "power transmission coil") and the coil of the power reception device (hereinafter, also referred to as "power reception coil"). , It is attracting attention that it can be charged efficiently over a longer distance.

Patent Document 1 discloses a technique for improving power feeding efficiency in a non-contact charging system based on a magnetic field resonance method. In this non-contact charging system, a relay device including a coil driving device is provided between the power transmission device and the power receiving device, and the coil of the relay device (hereinafter, also referred to as "relay coil") is provided according to the power transmission information of the power transmission device or the power receiving device. By adjusting the position of), the power supply efficiency is improved.

Japanese Unexamined Patent Publication No. 2011-147280

In the magnetic field resonance method, it is generally known that by providing a relay device that resonates with both the power transmission device and the power receiving device in a magnetic field between the power transmission device and the power receiving device, it is possible to increase the transmission distance and improve the power supply efficiency. Has been done. On the other hand, although the power supply efficiency can be adjusted by adjusting the position of the relay coil, the optimum position of the relay coil with respect to the fluctuation of the voltage value of the battery has not been generalized.

In the above technology, the relay coil is provided with a drive device, and the position of the relay coil can be adjusted according to the power transmission information of the power transmission device or the power receiving device. However, the optimum position of the relay coil with respect to the given power transmission information is not shown, and the position of the coil to be adjusted is only searched according to the map given by the user or by feedback or the like.

The present invention has been made in view of the above-mentioned problems, and provides a non-contact charging system capable of adjusting the position of a relay coil so as to suppress deterioration of charging efficiency when the battery voltage fluctuates. Aim to provide

The present invention relates to a non-contact charging system.
The non-contact charging system has a power transmission device that transmits the power to be supplied by the transmission coil, a relay device that relays the power transmitted by the transmission coil by the relay coil, and a power receiving coil that relays the power relayed by the relay coil. It includes a charging device that charges the battery, and a battery sensor that detects the value of the current flowing into the battery and the value of the voltage of the battery.

The relay device includes a drive device that moves the position of the relay coil.

The relay device receives information on the current value and the voltage value from the battery sensor, and the smaller the value obtained by dividing the current value by the voltage value (hereinafter, also referred to as “battery admittance value”), the more the relay coil is separated from the transmission coil. It is configured to control the drive unit.

The power loss depends on the current flowing through each device. Therefore, if the current flowing through each device fluctuates, the charging efficiency may deteriorate.

In a non-contact charging system provided with a relay device, the present inventor determines that the current flowing through the power transmission coil (hereinafter, also referred to as “transmission coil current”) and the current flowing through the relay coil (hereinafter, also referred to as “relay coil current”). , It was found that the current value change due to the voltage fluctuation of the battery and the current value change due to the fluctuation of the mutual inductance between the relay coil and the power receiving coil (hereinafter, also referred to as "reciprocal power receiving mutual inductance") have the opposite relationship. .. Here, the opposite relationship is that the transmission coil current decreases and the relay coil current increases as the battery voltage increases, and the transmission coil current increases and relays as the mutual inductance between relay and power increases. The coil current is to decrease.

According to the present invention, as the battery admittance value becomes smaller, that is, as the battery voltage increases, the relay coil is separated from the power transmission coil to adjust the mutual inductance between relays and power receivers. As a result, fluctuations in the power transmission coil current and the relay coil current due to the increase in the battery voltage can be suppressed, and deterioration of charging efficiency can be suppressed.

It is a figure which shows typically the structure of the non-contact charging system which concerns on embodiment. It is a conceptual diagram which shows the adjustment of the position of a relay coil by a drive device. It is a conceptual diagram which shows the adjustment of the position of a relay coil by a drive device when the movement of a relay coil is restricted to one axis. It is a figure which shows the simulation result of the current value of the transmission coil current and the relay coil current with respect to the distance between a transmission coil and a relay coil. It is a figure which shows the simulation result of the efficiency between coils with respect to the distance between a power transmission coil and a relay coil. It is a figure which shows typically the structure of the non-contact charging system when the relay device is integrated with the power transmission device. It is a figure which shows typically the structure of the non-contact charging system when the relay device is integrated with the power receiving device.

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

1. 1. Configuration example 1-1. Configuration of Embodiments FIG. 1 is a diagram schematically showing a configuration of a non-contact charging system 10 according to an embodiment of the present invention. The non-contact charging system 10 includes a power transmission device 100, a relay device 200, a power receiving device 300, an AC power supply 400, and a battery 500. The AC power supply 400 is connected to the power transmission device 100 and supplies electric power to the power transmission device 100. The AC power supply 400 is, for example, a household power supply having a voltage of 100 V and a frequency of 50 Hz. The battery 500 is connected to the power receiving device 300 and charges the power received by the power receiving device 300. The battery 500 is a rechargeable DC power source including a secondary battery such as a lithium ion battery or a nickel metal hydride battery. As will be described later, the power transmission device 100, the relay device 200, and the power receiving device 300 transmit power from the power transmission device 100 to the power receiving device 300 in a non-contact manner by causing the coils included in each device to resonate with each other in a magnetic field.

The power transmission device 100 includes a resonance circuit 101, an ADCC converter 110, an inverter 120, and a filter circuit 130. The ACDC converter 110 rectifies and transforms the power supplied from the AC power supply 400 and outputs it to the inverter 120. The ACDC converter 110 is composed of, for example, a rectifier circuit including a diode and a capacitor, and a buck-boost circuit including a semiconductor switching element (IGBT, MOSFET, etc.). The inverter 120 converts the DC power received from the ACDC converter 110 into AC power having a predetermined frequency. The inverter 120 is composed of, for example, a plurality of semiconductor switching elements and a single-phase full bridge circuit including a plurality of feedback diodes, and performs pulse width modulation processing (PWM). The frequency of the output power of the inverter 120 is controlled by the control circuit 140 so as to match the resonance frequency of the resonance circuit 301 described later. Hereinafter, the frequency of the output power of the inverter 120 is also referred to as “ω”. The filter circuit 130 reduces the electromagnetic noise of the electric power output from the inverter 120. The filter circuit 130 is, for example, a low-pass filter composed of a capacitor and a coil.

The resonance circuit 101 includes a power transmission coil L1 and a resonance capacitor C1 connected in series with the power transmission coil L1. The resonance frequency of the resonance circuit 101 is configured to match the resonance frequency of the resonance circuit 301, which will be described later. The power transmission coil L1 resonates with the relay coil L2, which will be described later, in a magnetic field by the power output from the inverter 120 at the resonance frequency, and transmits the power to the relay device 200.

The power transmission device 100 includes several sensors. The sensor 141 detects the current flowing through the power transmission coil L1 with the current sensor. The sensor 142 detects the output current of the inverter 120 with a current sensor. The sensor 143 detects the output current of the ACDC converter with a current sensor. The sensor 144 detects the input voltage of the inverter 120 with a voltage sensor.

The relay device 200 includes a resonance circuit 201 and a drive device 210. The resonance circuit 201 includes a relay coil L2 and a resonance capacitor C2 connected in series with the relay coil L2. The resonance frequency of the resonance circuit 201 is configured to match the resonance frequency of the resonance circuit 301, which will be described later. The relay coil L2 receives the electric power transmitted from the power transmitting device 100 by magnetically resonating with the power transmitting coil L1 and the power receiving coil L3, and transmits the received power to the power receiving device 300.

The drive device 210 is connected to the resonance circuit 201 and is configured so that the position of the relay coil L2 can be moved in the vertical direction or the front-back and left-right directions. The adjustment of the position of the relay coil L2 is controlled by the control circuit 240 described later. The drive device 210 is composed of, for example, a motor or a positioner.

The relay device 200 includes a sensor 241. The sensor 241 detects the current flowing through the relay coil L2 with a current sensor.

The power receiving device 300 includes a resonance circuit 301, a rectifier circuit 310, and a filter circuit 330. The resonance circuit 301 includes a power receiving coil L3 and a resonance capacitor C3 connected in series with the power receiving coil L3. As described above, the resonance frequency of the resonance circuit 301 is configured to match the frequency of the output power of the inverter 120. The power receiving coil L3 resonates with the relay coil L2 in a magnetic field and receives electric power from the relay device 200.

The rectifier circuit 310 is composed of a voltage doubler rectifier circuit including, for example, a single-phase full-wave rectifier circuit using a plurality of diodes and a capacitor connected in parallel after the single-phase full-wave rectifier circuit. The rectifier circuit 310 further includes a smoothing capacitor, converts the input AC power into smoothed DC power, and outputs the power.

The power receiving device 300 includes battery sensors 343 and 344. The battery sensor 343 detects the current flowing through the battery 500 (hereinafter, also referred to as “battery current”) with the current sensor. The battery sensor 344 detects the voltage of the battery 500 (hereinafter, also referred to as “battery voltage”) with the voltage sensor. The power receiving device 300 further includes some sensors. The sensor 341 detects the current flowing through the power receiving coil L3 with a current sensor. The sensor 342 detects the output current of the filter circuit 330 with a current sensor.

In order to efficiently transmit electric power, it is desirable that the Q value of the resonance circuit 101, the resonance circuit 201, and the resonance circuit 301 is 100 or more.

The power transmission device 100 further includes a control circuit 140 and a communication circuit 150. The control circuit 140 controls the semiconductor switching element of the ADCC converter 110 and the semiconductor switching element of the inverter 120, and adjusts the electric power input to the resonance circuit 101. Here, the power input to the resonance circuit 101 is adjusted so that the frequency matches the resonance frequencies of the resonance circuit 101 and the resonance circuit 301. The control circuit 140 includes at least an input / output interface, at least one memory, and at least one processor. The input / output interface receives the detection value of each sensor included in the power transmission device 100 and the communication information taken from the communication circuit 150 described later as inputs, and controls the control signal to the ADCC converter 110 and the inverter 120, and communicates with the communication circuit 150. Information and output. The memory includes a RAM (Random Access Memory) for temporarily recording data and a ROM (Read Only Memory) for storing control programs and the like. The processor reads a control program or the like from the memory and executes it, and generates a control signal based on the captured input value.

The communication circuit 150 is wirelessly or electrically connected to the communication circuit 250 provided in the relay device 200 and the communication circuit 350 provided in the power receiving device 300, which will be described later, and is configured to be able to communicate information with each other. The communication circuit 150 outputs the information taken from the control circuit 140 to the communication circuit 250 and the communication circuit 350, and outputs the communication information taken from the communication circuit 250 and the communication circuit 350 to the control circuit 140. The information captured by the communication circuit 150 from the control circuit 140 includes the detection value of each sensor of the power transmission device 100.

The relay device 200 further includes a control circuit 240 and a communication circuit 250. The control circuit 240 controls the drive device 210 so as to adjust the relay coil L2 to a predetermined position. The control circuit 140 includes at least an input / output interface, at least one memory, and at least one processor. The input / output interface inputs the detection value of the sensor 241 and the communication information taken from the communication circuit 250 described later, and outputs the control signal to the drive device 210 and the communication information to the communication circuit 250. The memory includes a RAM for temporarily recording data and a ROM for storing a control program and the like. The processor reads a control program or the like from the memory and executes it, and generates a control signal based on the captured input value.

As described above, the communication circuit 250 is wirelessly or electrically connected to the communication circuit 150 and the communication circuit 350, and is configured to be able to communicate information with each other. The communication circuit 250 outputs the information taken from the control circuit 240 to the communication circuit 150 and the communication circuit 350, and outputs the communication information taken from the communication circuit 150 and the communication circuit 350 to the control circuit 240. The information captured by the communication circuit 250 from the control circuit 240 includes the detection value of the sensor 241 of the relay device 200.

The power receiving device 300 further includes a control circuit 340 and a communication circuit 350. The control circuit 340 includes at least an input / output interface, at least one memory, and at least one processor. The input / output interface inputs the detection value of each sensor included in the power receiving device 300 and the communication information taken from the communication circuit 350 described later, and outputs the communication information to the communication circuit 350. The memory includes a RAM for temporarily recording data and a ROM for storing a control program and the like. The processor reads a control program or the like from the memory and executes it, and generates a control signal based on the captured input value.

As described above, the communication circuit 350 is wirelessly or electrically connected to the communication circuit 150 and the communication circuit 250, and is configured to be able to communicate information with each other. The communication circuit 350 outputs the information taken from the control circuit 340 to the communication circuit 150 and the communication circuit 250, and outputs the communication information taken from the communication circuit 150 and the communication circuit 250 to the control circuit 340. The information captured by the communication circuit 350 from the control circuit 340 includes the detection value of each sensor of the power receiving device 300.

The information communicated between the communication circuit 150, the communication circuit 250, and the communication circuit 350 and shared by the control circuit 140, the control circuit 240, and the control circuit 340 is the detection value of each sensor of the power transmission device 100 and the information of the relay device 200. It includes the detected value of the sensor 241 and each detected value of the power receiving device 300, and information of the other non-contact charging system 10. Here, the other non-contact charging system 10 information includes information on the non-contact charging system 10 stored in advance in the ROM of the control circuit of each device (parameters of each element included in the non-contact charging system 10 and non-contact). Information on the device on which the charging system 10 is mounted), error information notifying that charging cannot be continued due to a failure, and contactless charging system 10 in which the communication circuit of each device is captured through an information transmission path (not shown). Information etc.

1-2. Characteristics of the system Some characteristics of the non-contact charging system 10 according to the embodiment of the present invention will be described.

When the mutual inductance between the transmission coil L1 and the relay coil L2 _{is represented by "M 12} " and the mutual inductance between the relay coil L2 and the power receiving coil L3 _{is represented by "M 23} ", the transmission coil current I ₁ and the relay coil current are represented by "M 23". The power _{receiving coil current I 2} and the power receiving coil current I ₃ can be represented by the proportional relationship of the equations (1) to (3), respectively.

Here, "V _bat " and "P _bat " represent the battery voltage and the input power to the battery 500, respectively. The mutual inductances M ₁₂ and M ₂₃ depend on the coupling coefficient between the transmission coil L1 and the relay coil L2 and the coupling coefficient between the relay coil L2 and the power receiving coil L3, respectively. As the distance between the coils increases, the coupling coefficient decreases and the mutual inductance decreases. Conversely, as the distance between the coils decreases, the coupling coefficient increases and the mutual inductance increases.

From the equations (1) and (2), when the battery voltage V _batt increases, the transmission coil current I ₁ decreases and the relay coil current I ₂ increases. On the other hand, when the mutual inductance M ₂₃ increases, the transmission coil current I ₁ increases and the relay coil current I ₂ decreases. That is, the fluctuations of the transmission coil current I ₁ and the relay coil current I ₂ with respect to the battery voltage V _butt and the fluctuations of the transmission coil current I ₁ and the relay coil current I ₂ with respect to the mutual inductance M ₂₃ have the opposite relationship.

The inter-coil efficiency η can be expressed by the equation (4). Here, "r ₁ ", "r ₂ ", and "r ₃ " represent the resistance components of the power transmission device 100, the relay device 200, and the power receiving device 300, respectively, and " _RL " represents the load resistance of the battery 500.

As shown in the equation (4), the inter-coil efficiency η changes depending on the value of the current flowing through each device.

2. Adjustment of Relay Coil Position The adjustment of the position of the relay coil L2 by the control circuit 240 and the drive device 210 will be described below.

From the equation (4), the power transmission coil current I ₁ and the relay coil current I ₂ that maximize the inter-coil efficiency η are given. By adjusting the position of the relay coil L2 and adjusting the mutual inductances M ₁₂ and M ₂₃ with respect to a certain battery voltage V _{batt , the transmission coil current I 1} and the relay coil current I _{2 that} maximize the inter-coil efficiency η are obtained. Can drive the non-contact charging system 10. When charging continues and the battery voltage V _batt increases, the power transmission coil current I ₁ and the relay coil current I ₂ fluctuate as described above. As a result, the inter-coil efficiency η changes, and the charging efficiency deteriorates.

Therefore, in the control circuit 240 of the relay device 200 according to this embodiment, as the battery voltage V _batt increases and the battery admittance value decreases, the position of the relay coil L2 is separated from the power transmission coil L1. To control.

When the position of the relay coil L2 is separated from the power transmission coil L1, the mutual inductance M ₂₃ increases and M ₁₂ decreases. Thereby, as shown in the equations (1) and (2) _{, the transmission coil current I 1} and the relay coil current I ₂ can be adjusted so as to cancel the fluctuation of the _{battery voltage V batt.} That is, by suppressing the fluctuation of the current value, it is possible to suppress the deterioration of the charging efficiency.

2-1. Operation of Control Circuit 240 and Drive Device 210 The control circuit 240 acquires the _{battery current I batt} and the battery voltage V _{batt from the battery sensors 343 and 344.} The control circuit 240 calculates the battery admittance value obtained by dividing the _{battery current I batt} by the battery voltage V _batt. The control circuit 240 transmits a control signal to the drive device 210 so that the position of the relay coil L2 is separated from the power transmission coil L1 as the calculated battery admittance value becomes smaller. The drive device 210 adjusts the position of the relay coil L2 based on the received control signal.

FIG. 2 is a conceptual diagram showing adjustment of the position of the relay coil L2. The position A is the position of the relay coil L2 at a certain battery voltage value. When charging continues and the battery voltage V _batt increases, the control circuit 240 transmits a control signal requesting the drive device 210 to adjust the position of the relay coil L2 so as to suppress fluctuations in the current value. do. The drive device 210 moves the relay coil L2 to the position B based on the control signal. Here, the position adjustment of the relay coil L2 may be limited to one axis. FIG. 3 is a conceptual diagram showing a case where the position adjustment of the relay coil L2 is limited only in the vertical direction.

FIG. 4 is a diagram showing simulation results of the current values of the _{power transmission coil current I 1} and the relay coil current I ₂ with respect to the distance between the power transmission coil L1 and the relay coil L2 (the distance between the power transmission / relay coil). It can be seen that the fluctuations _{of the power transmission coil current I 1} and the relay coil current I ₂ can be suppressed by adjusting the position of the relay coil L2 with respect to the increase in the battery voltage. It is also possible to reduce the maximum value of the current value, which can lead to a reduction in the number of elements in the circuit and a reduction in the coil diameter.

FIG. 5 is a diagram showing a simulation result of the inter-coil efficiency η with respect to the distance between the power transmission coil L1 and the relay coil L2 (distance between the power transmission / relay coil). It can be seen that the deterioration of the inter-coil efficiency η can be suppressed by adjusting the position of the relay coil L2 with respect to the increase in the battery voltage V _batt.

As described above, according to the non-contact charging system 10 of the present embodiment, the relay coil L2 suppresses the fluctuations of the power transmission coil current I ₁ and the relay coil current I _{2 with respect to the fluctuation of the battery voltage V batt.} By adjusting the position of, the deterioration of charging efficiency can be suppressed.

3. 3. Modification example of the non-contact charging system of the embodiment The non-contact charging system 10 of the embodiment may adopt a modified mode as follows.

3-1. Modification 1
The relay device 200 may be configured to be integrated with the power transmission device 100. FIG. 6 is a diagram schematically showing a configuration when the relay device 200 is integrated with the power transmission device 100. At this time, the functions of the control circuit 240 and the communication circuit 250 of the relay device 200 shown in FIG. 1 are integrated into the control circuit 140 and the communication circuit 150 of the power transmission device 100.

3-2. Modification 2
The relay device 200 may be configured to be integrated with the power receiving device 300. FIG. 7 is a diagram schematically showing a configuration when the relay device 200 is integrated with the power receiving device 300. At this time, the functions of the control circuit 240 and the communication circuit 250 of the relay device 200 shown in FIG. 1 are integrated into the control circuit 340 and the communication circuit 350 of the power receiving device 300.

10 Non-contact charging system, 100 power transmission device, 200 relay device, 210 drive device, 240 control circuit, 300 power receiving device, 343 battery sensor, 344 battery sensor, 400 AC power supply, 500 battery

Claims (1)

It is a non-contact charging system that charges electric power in a non-contact manner.
A power transmission device that transmits the power to be supplied by a power transmission coil,
A relay device that relays the electric power transmitted by the power transmission coil with the relay coil,
A power receiving device that receives power relayed by the relay coil by the power receiving coil and charges the battery.
A battery sensor that detects the current value flowing into the battery and the voltage value of the battery,
With
The relay device is
A drive device for moving the position of the relay coil is included.
The drive device is configured to receive information on the current value and the voltage value from the battery sensor and control the drive device so that the relay coil is separated from the power transmission coil as the value obtained by dividing the current value by the voltage value becomes smaller. A non-contact charging system characterized by being.

Images