Electric field coupling type non-contact power supply system

Abstract

According to the present invention, an output voltage or an output current is kept constant with respect to positional deviation between the electrodes of power transmission / reception pad parts, and soft switching is maintained, without increasing circuit complexity. In this electric field coupling type non-contact power supply system, a power transmission device and a power reception device are capacitively coupled via first and second electrodes of power transmission / reception pad parts. The power transmission device includes: an inverter circuit that converts a DC voltage into an AC voltage by switching and outputs the AC voltage to the first electrode via an external capacitor; and the first electrode. The power reception device includes: the second electrode; and a rectifier circuit that converts the AC voltage received via the second electrode into a DC voltage and outputs the DC voltage to a load. The inverter circuit performs zero voltage switching (ZVS) or zero current switching (ZCS) on the DC voltage while an output voltage or an output current output to the load is constant. The capacitance value of the external capacitor is smaller than the capacitance value of a capacitor between the first and second electrodes.

Description

Electric field coupled contactless power supply system

[0001] This invention relates to an electric field coupled non-contact power supply system.

[0002] For example, secondary batteries mounted on mobile devices such as automated guided vehicles (AGVs, AMRs, etc.) are charged using an electric field-coupled contactless power supply system via a power-transmitting pad section (see, for example, Patent Document 1). In this contactless power supply system, one or two pairs of electrodes constituting power-transmitting pad sections are provided in the power-transmitting device and the power-receiving device, respectively, and electrical energy is transmitted using a parallel plate type capacitor when they come close to each other.

[0003] The advantages of this contactless power supply system are as follows: (1) It can be made from metal plates such as aluminum plates, making it lightweight and inexpensive. (2) Because the electric field between electrodes is mainly limited to the area between the electrodes, there is little leakage flux and the influence of metallic foreign matter is small, making it robust in metallic environments.

[0004] Japanese Patent Publication No. 2024-040809

[0005] Kazuma Shinode, et al., "Capacitive Power Transfer System Using a Local-independent Class E Zero Voltage Switching Parallel Resonant Inverter and a Class D Voltage-Driven Rectifier," IEEE Transactions on Circuits and Systems, Vol. 14, No. 8, August 2021.Yutaro Komiyama et al., "Analysis and Design of High-Frequency WPT System Using Load-Independent Inverter With Robustness Against Load Variations and Coil Misalignment," IEEE Access, Vol. 12, pp.23043-23056, 2024

[0006] However, considering the practical applications of electric field-coupled contactless power supply systems, it is necessary to maintain constant output characteristics (voltage or current) and high efficiency regardless of the misalignment of the coupling capacitor (transmitting and receiving pad). To achieve this, control feedback (transmitting information from the receiving device to the transmitting device) has generally been used. However, this method has problems such as increased circuit complexity and delays associated with communication control. Therefore, misalignment-independent designs that do not require a control system between the receiving and transmitting devices are attracting attention. Here, since there is no circuit that is robust to the misalignment of the coupling capacitor without control, it was necessary to maintain a constant output voltage and high efficiency against the misalignment of the coupling capacitor without control.

[0007] The object of the present invention is to provide an electric field-coupled non-contact power supply system that, compared to the prior art, does not require a complex circuit, maintains a constant output voltage or output current even with respect to misalignment between electrodes in the power transmission and reception pad section, and maintains soft switching of ZVS or ZCS.

[0008] An electric field coupling type non-contact power supply system according to an aspect of the present disclosure is an electric field coupling type non-contact power supply system in which a power transmission device and a power reception device are capacitively coupled via first and second electrodes of a power transmission / reception pad unit. The power transmission device includes an inverter circuit including an external capacitor, which converts a DC voltage into an AC voltage by switching and outputs the AC voltage to the first electrode via the external capacitor, and the first electrode. The power reception device includes the second electrode and a rectifier circuit that converts the AC voltage received via the second electrode into a DC voltage and outputs the DC voltage to a load. The inverter circuit causes the output voltage or output current output to the load to be constant and performs zero voltage switching (ZVS) or zero current switching (ZCS) on the DC voltage. The capacitance value of the external capacitor is set to be smaller than the capacitance value of the capacitor between the first and second electrodes.

[0009] Therefore, according to the electric field coupling type non-contact power supply system according to an aspect of the present disclosure, compared with the prior art, the circuit does not become complicated, and the output voltage or output current can be kept constant with respect to the displacement between the electrodes of the power transmission / reception pad unit.

[0010] It is a block diagram showing a configuration example of an electric field coupling type non-contact power supply system according to Embodiment 1. It is a block diagram showing a configuration example of an electric field coupling type non-contact power supply system according to Embodiment 2. In FIG. 2, capacitance value C ｔ = 2000 pF and inductance L ｔ = 1.42 μH, the graph showing the relationship of the capacitance value C ０ (=(C ｔ C ｐ / (C ｔ + C ｐ )) with respect to the output voltage V ｏ and the capacitance value C ｐ . In FIG. 3A, it is a table showing an example of a preferable range of the capacitance value ratio C ｐ / C ｔ . In FIG. 2, capacitance value C ｔ = 500 pF and inductance L ｔ = 2.25 μH, the capacitance value C ０ (=(C ｔ C ｐ / (C ｔ +C ｐ Output voltage V for )) ｏ and capacity value C ｐ This graph shows the relationship between the volume value ratio C. In Figure 4A, the volume value ratio C ｐ / C ｔ This is a table showing an example of a preferred range. This is a circuit diagram showing an example configuration of a load-independent E / F class inverter circuit 3A used in the electric field-coupled contactless power supply system of Figure 2. This is a circuit diagram showing an example configuration of a push-pull load-independent E / F class inverter circuit 3B used in the electric field-coupled contactless power supply system of Figure 2. This is a circuit diagram showing an example configuration of a load-independent E class inverter circuit 3C used in the electric field-coupled contactless power supply system of Figure 2. This is a circuit diagram showing an example configuration of a load-independent E class inverter circuit 3D used in the electric field-coupled contactless power supply system of Figure 2. This is a circuit diagram showing an example configuration of a load-independent inverse E class inverter circuit 3E used in the electric field-coupled contactless power supply system of Figure 2. This is a circuit diagram showing an example configuration of a load-independent inverse E class inverter circuit 3F used in the electric field-coupled contactless power supply system of Figure 2. This is a circuit diagram showing an example configuration of a half-bridge current-driven D class rectifier circuit 5A used in the electric field-coupled contactless power supply system of Figure 2. This is a circuit diagram showing an example configuration of a full-bridge current-driven Class D rectifier circuit 5B used in the electric field-coupled contactless power supply system shown in Figure 2. This is a circuit diagram showing an example configuration of a half-bridge voltage-driven Class D rectifier circuit 5C used in the electric field-coupled contactless power supply system shown in Figure 2. This is a circuit diagram showing an example configuration of a full-bridge voltage-driven Class D rectifier circuit 5D used in the electric field-coupled contactless power supply system shown in Figure 2. This is a circuit diagram showing an example configuration of a load-independent Class E rectifier circuit 5E used in the electric field-coupled contactless power supply system shown in Figure 2. This is a circuit diagram showing an example configuration of a load-independent Class E / F rectifier circuit 5F used in the electric field-coupled contactless power supply system shown in Figure 2. This is a circuit diagram showing the configuration of an electric field-coupled contactless power supply system according to Conventional Example 1. This is a circuit diagram showing the configuration of an electric field-coupled contactless power supply system according to a modified example of Conventional Example 1. This is a circuit diagram showing the configuration of a contactless power supply system according to Conventional Example 2.

[0011] Embodiments and modified examples of the present invention will be described below with reference to the drawings. The same or similar components are denoted by the same reference numerals.

[0012] (Inventor's insights)

[0013] Figure 7A is a circuit diagram (Figure 1 of Non-Patent Document 1) showing the configuration of a conventional electric field coupled non-contact power supply system according to Conventional Example 1 disclosed in Non-Patent Document 1. In Figure 7A, the input DC voltage V ｉｎ The power is switched by the switching element S of the power transmission device, and then rectified and smoothed by the rectifier and smoothing circuit 401 of the power receiving device via the power transmission and receiving pad section 411 to produce the output voltage V. ｏ The output is then sent to the load resistor R. Here, the power transmitting and receiving pad section 411 has two pairs of electrodes (P １ , P ３ ;P ２ , P ４ ) is included in the configuration, and the inter-electrode capacitor C １３ , C ２４ And, leakage capacitor C １２ , C ３４ This can be illustrated with an equivalent circuit including the two pairs of electrodes (P １ , P ３ ;P ２ , P ４ ) Intercompatibility capacitance value C ｍ It can be expressed by the following equation (see equation (4) in Non-Patent Document 1).

[0014] (1)

[0015] Here, electrode P １ and P ４ The leakage capacitor between them is C. １４ And electrode P ２ and P ３ The leakage capacitor between them is C. ２３ In the electric field coupled non-contact power supply system shown in Figure 7A (Figure 1(a) of Non-Patent Document 1), the power transmission / receiving pad section 411 is a capacitor C ａ , C ｂ Parallel capacitor C １ The circuit 403 of the power transmission / receiving pad section is replaced, and the rectifier / smoothing circuit 401 is replaced with a load resistor R ２Figure 7B shows the equivalent circuit (Figure 1(e) of Non-Patent Document 1) obtained by replacing and modifying the circuit. In the equivalent circuit of Figure 7B, the load resistor R is located at the terminal end of the power transmission / reception pad section. ２ The impedance Z when viewed ２ It can be expressed by the following equation (see equation (7) in Non-Patent Document 1).

[0016] (2)

[0017] Here, ω is the driving angular frequency of the switching element S, and R １ This is the load resistance of the intermediate equivalent circuit from Figure 7A to Figure 7B (Figure 1(d) of Non-Patent Document 1), and P ｒ V is the output power. ｍ This is the output voltage.

[0018] As is clear from equations (1) and (2), the output voltage V ｍ The mutual coupling capacitance value C of the power transmission / receiving pad section 403 ｍ It depends on the mutual coupling capacitance value C. ｍ Since this changes due to the misalignment between electrodes of the power transmission / receiving pad section 403, it does not have characteristics that are independent of misalignment. In other words, the non-contact power supply system according to Conventional Example 1 disclosed in Non-Patent Document 1 has characteristics that are independent of load fluctuations, but does not have characteristics that are independent of misalignment. The embodiments shown below provide a non-contact power supply system that has characteristics that are independent of load fluctuations and characteristics that are independent of misalignment.

[0019] Figure 8 is a circuit diagram showing the configuration of a contactless power supply system according to Conventional Example 2 disclosed in Non-Patent Document 2. The contactless power supply system in Figure 8 comprises a power transmission device 101, a coupling unit 311, and a power receiving device 201. Here, the power transmission device 101 is configured with a load-independent E / F class amplifier, and the coupling unit 311 is configured with a series-connected capacitor C １ , C ２ And the electromagnetically coupled inductor L １ , L ２ The system is configured to include the above. The power receiving device 201 is also configured to include a current-driven Class D rectifier circuit 211 and a buck converter 212.

[0020] Conventional Example 2 in Figure 8 is characterized by being configured so that the output voltage or output current remains constant, for example, in relation to changes in voltage or current due to the remaining charge or charging of the secondary battery (i.e., load fluctuations).

[0021] (Embodiment 1) In contrast, in Embodiment 1, as shown in Figure 1, the coupling capacitor C of the power transmission / reception pad section 4 ｐ１ , C ｐ２ (Series capacitance C ｐ＝ (C ｐ１ ・C ｐ２ ) / (C ｐ１ +C ｐ２ An external capacitor C with a small capacitance value, preferably, for example, a sufficiently small capacitance value, relative to the other capacitors. ｔ (C ｔ <C ｐ or C ｔ ≪C ｐ A new concept is introduced in which the coupling capacitor C of the power transmission / receiving pad section 4 is inserted in series. ｐ１ , C ｐ２ The system is characterized by its independence from misalignment, that is, achieving a constant output voltage or output current, and ZVS or ZCS. In other words, by combining the inverter circuit shown in Figure 8 with this new concept, a contactless power supply system is provided that, compared to conventional technology, does not complicate the circuit and can maintain a constant output voltage or output current in response to both misalignment between the electrodes of the power transmitting and receiving pads and load fluctuations, while also maintaining soft switching of ZVS or ZCS.

[0022] Here, "load-independent" refers to a state in which the output voltage or current remains constant even when the load impedance value fluctuates, achieving ZVS (Zero Voltage Switching) or ZCS (Zero Current Switching). This reduces switching losses and makes it possible to maintain high efficiency at high frequencies. In previous research, a load-independent design of an electric field-coupled contactless power supply system using a Class E inverter has been proposed (see, for example, Non-Patent Document 1).

[0023] Figure 1 is a block diagram showing an example configuration of an electric field-coupled contactless power supply system according to Embodiment 1. In Figure 1, the electric field-coupled contactless power supply system comprises a power transmission device 100, a power transmission / receiving pad section 4, and a power receiving device 200. Here, the power transmission device 100 includes a power factor correction circuit (PFC circuit) 2 and an external capacitor C at the end. ｔ The system is configured with an inverter circuit 3 having a coupling capacitor C, for example, two pairs of electrodes. ｐ１ , C ｐ２ The device is configured to include the following. The power receiving device 200 is also configured to include a rectifier circuit 5 and a DC-DC converter circuit 6.

[0024] In the electric field-coupled contactless power supply system configured as described above, the AC voltage from the AC power source 1 is converted to a DC voltage and its power factor is improved by the power factor correction circuit 2, and then output to the inverter circuit 3. The inverter circuit 3 converts the input DC voltage to an AC voltage by switching it, for example, using a switching element, and then outputs it to the terminating external capacitor C ｔ AC power from the power receiving device 200 is transmitted via the power transmission / receiving pad section 4.

[0025] The rectifier circuit 5 of the power receiving device 200 rectifies the input AC voltage into a DC voltage and then outputs it to the DC-DC converter circuit 6. The DC-DC converter circuit 6 converts the input DC voltage into a predetermined DC voltage and then outputs it to the load 7.

[0026] According to the above embodiment 1, as shown in Figure 1, the coupling capacitor C of the power transmission / receiving pad section 4 ｐ１ , C ｐ２ (Series capacitance C ｐ An external capacitor C with a small, preferably for example, sufficiently small capacitance value relative to ) ｔ (C ｔ <C ｐ or C ｔ ≪C ｐ ) is inserted in series. This results in the coupling capacitor C of the power transmission / reception pad section 4. ｐ１ , C ｐ２It is possible to achieve load-independent characteristics such as a constant output voltage or a constant output current with respect to the displacement and to maintain soft switching of ZVS or ZCS. Further, by using the circuit of FIG. 8 as the inverter circuit 3 and the rectifier circuit 5, a non-contact power feeding system can be provided that does not become more complex than the prior art and can maintain a constant output voltage or output current with respect to both the displacement between the electrodes of the power transmitting and receiving pad portion and load fluctuations.

[0027] (Embodiment 2) FIG. 2 is a block diagram showing a configuration example of a capacitive coupling type non-contact power feeding system according to Embodiment 2. In FIG. 2, the inverter circuit 3 is, for example, a load-independent type E / F class inverter circuit, and includes (1) an input inductor L Ｃ and (2) a switching element Q which is, for example, an N-channel MOSFET, and (3) a shunt capacitor C Ｓ and (4) inductors L ｈ , L ｔ and a capacitor C ｈ and an LC resonance circuit including them, and (5) a terminal external capacitor C ｔ and (6) a control circuit 10 that generates a predetermined switching gate control voltage v ｇｓ and is configured to include them.

[0028] Further, the rectifier circuit 5 is, for example, a half-bridge current-driven type D-class rectifier circuit, and includes (1) capacitors C ２ , C ３ and an inductor L ３ and an LC resonance circuit including them, and (2) a half-bridge rectifier including diodes D １ , D ２ and (3) a smoothing capacitor C ｆ and is configured to include them. The rectifier circuit 5 rectifies and smooths the AC voltage from the power transmitting and receiving pad portion 4, and then outputs the rectified and smoothed DC voltage to the load 7, for example, the load resistor R Ｌ .

[0029] The inverter circuit 3 of the non-contact power feeding system configured as described above receives the DC voltage V Ｉ from the DC power supply 8 as a predetermined switching gate control voltage v ｇｓBy using this method for switching, a constant current flows through the load 7 or a constant voltage is maintained regardless of the resistance value of the load 7, and ZVS or ZCS soft switching is performed.

[0030] Here, the coupling capacitor C of the power transmission / reception pad section 4. ｐ１ , C ｐ２ (Series capacitance C ｐ An external capacitor C with a small, preferably for example, sufficiently small capacitance value relative to ) ｔ (C ｔ <C ｐ or C ｔ ≪C ｐ ) is inserted in series. This results in the coupling capacitor C of the power transmission / reception pad section 4. ｐ１ , C ｐ２ This system achieves load-independent characteristics of a constant output voltage or output current despite misalignment, and enables ZVS or ZCS soft switching. Furthermore, by using the circuits shown in Figure 8 as the inverter circuit 3 and rectifier circuit 5, a contactless power supply system can be provided that is less complex than conventional technology and can maintain a constant output voltage or output current despite both misalignment between the electrodes of the power transmitting and receiving pads and load fluctuations.

[0031] Next, the coupling capacitance C of the power transmission / receiving pad section 4 in the contactless power supply system shown in Figure 2. ｐ And the capacitance value C of the external capacitor to be inserted. ｔ An example of the relationship is explained below.

[0032] Figure 3A shows the volume value C in Figure 2. ｔ = 2000 pF and inductance L ｔ = Volume value C when 1.42 μH ０ (=(C ｔ C ｐ / (C ｔ +C ｐ Output voltage V for )) ｏ and capacity value C ｐ This graph shows the relationship between the volume value ratio C in Figure 3A. ｐ / C ｔ This table shows an example of a preferred range.

[0033] Figure 4A shows the volume value C in Figure 2.ｔ = 500pF and inductance L ｔ = Volume value C at 2.25 μH ０ (=(C ｔ C ｐ / (C ｔ +C ｐ Output voltage V for )) ｏ and capacity value C ｐ This graph shows the relationship between the volume value ratio C in Figure 4A. ｐ / C ｔ This table shows an example of a preferred range.

[0034] In the circuits shown in Figures 3A and 4A, a fluctuation of approximately 10% in the output voltage is considered to be within a practically acceptable range, and this range was used for the judgment. In addition to the examples given in Figures 3A and 4A, other examples can be given where the capacitance values ​​or inductance are changed. In those cases, the coupling capacitance and capacitance ratio at which the output voltage remains nearly constant will be different values.

[0035] (Modification of the embodiment) In the above embodiment, the power transmission / receiving pad section 4 is, for example, a coupling capacitor C which is two pairs of electrodes. ｐ１ , C ｐ２ The present invention is configured to include, but is not limited to, for example, a coupling capacitor C which is a pair of electrodes. ｐ It may also be configured to include, for example, multiple coupling capacitors C which are multiple pairs of electrode pairs. ｐ It may be configured to include the following:

[0036] (Inverter circuit used in the embodiment) The inverter circuit used in the embodiment is described below. Note that the switching gate control voltage v ｇｓ ,v ｇｓ１ ,v ｇｓ２ These are generated by the control circuit 10.

[0037] Figure 5A is a circuit diagram showing an example configuration of a load-independent E / F class inverter circuit 3A used in the electric field-coupled contactless power supply system shown in Figure 2. In Figure 5A, the inverter circuit 3A consists of: (1) an input inductor L Ｉ (2) a switching element Q which is, for example, an N-channel MOSFET, and (3) a shunt capacitor CＳ (4) Inductor L ｔ , L ２ and capacitor C ２ (5) External capacitor C ｔ It is composed of including and .

[0038] The inverter circuit 3A configured as described above receives the DC voltage V from the DC power supply 8. Ｉ A predetermined switching gate control voltage v ｇｓ By using this switching mechanism, a constant current flows through the load 7 or a constant voltage is maintained, and ZVS or ZCS is performed, regardless of the resistance value of the load 7.

[0039] Figure 5B is a circuit diagram showing an example configuration of a push-pull load-independent E / F class inverter circuit 3B used in the electric field-coupled contactless power supply system shown in Figure 2. In Figure 5B, the inverter circuit 3B consists of: (1) an input inductor L Ｉ , L Ｉａ (2) For example, a switching element Q which is an N-channel MOSFET. １ Q ２ (3) Shunt capacitor C Ｓ , C Ｓａ (4) Inductor L ｔ , L ２ , L ２ａ and capacitor C ２ , C ２ａ (5) External capacitor C ｔ It is composed of including and .

[0040] The inverter circuit 3B configured as described above receives the DC voltage V from the DC power supply 8. Ｉ A predetermined switching gate control voltage v ｇｓ１ ,v ｇｓ２ By using this switching mechanism, a constant current flows through the load 7 or a constant voltage is maintained, and ZVS or ZCS is performed, regardless of the resistance value of the load 7.

[0041] Figure 5C is a circuit diagram showing an example configuration of a load-independent Class E inverter circuit 3C used in the electric field-coupled contactless power supply system shown in Figure 2. In Figure 5C, the inverter circuit 3C consists of: (1) an input inductor LＩ (2) a switching element Q which is, for example, an N-channel MOSFET, and (3) a shunt capacitor C Ｓ (4) Inductor L ｔ and external capacitor C ｔ It consists of an LC resonant circuit including and .

[0042] The inverter circuit 3C configured as described above receives the DC voltage V from the DC power supply 8. Ｉ A predetermined switching gate control voltage v ｇｓ By using this switching mechanism, a constant voltage is applied to the load 7 or a constant current flows through it, and ZVS or ZCS is performed, regardless of the resistance value of the load 7.

[0043] Figure 5D is a circuit diagram showing an example configuration of a load-independent Class E inverter circuit 3A used in the electric field-coupled contactless power supply system shown in Figure 2. In Figure 5D, the inverter circuit 3D consists of: (1) an input inductor L Ｉ , L Ｃ (2) a switching element Q which is, for example, an N-channel MOSFET, and (3) an inductor L ｔ and capacitor C ｔ It consists of an LC resonant circuit including and .

[0044] The inverter circuit 3D configured as described above receives the DC voltage V from the DC power supply 8. Ｉ A predetermined switching gate control voltage v ｇｓ By using the inductor L to switch, a constant current flows through the load 7 or a constant voltage is maintained, and ZVS or ZCS is performed, regardless of the resistance value of the load 7. ｔ and capacitor C ｔ An LC resonant circuit including this may be provided in the rectifier circuit 5.

[0045] Figure 5E is a circuit diagram showing an example configuration of a load-independent inverse E-class inverter circuit 3E used in the electric field-coupled contactless power supply system shown in Figure 2. In Figure 5E, the inverter circuit 3E consists of: (1) an input inductor L Ｃ (2) a switching element Q which is, for example, an N-channel MOSFET, and (3) a shunt capacitor C Ｓand switching smoothing inductor L Ｓ (4) Capacitor C １ (5) External capacitor C ｔ and termination inductor L ｔ It is composed of including and .

[0046] The inverter circuit 3E configured as described above receives the DC voltage V from the DC power supply 8. Ｉ A predetermined switching gate control voltage v ｇｓ By using this to switch, ZCS is performed so that the voltage across load 7 remains constant regardless of the resistance value of load 7. Note that external capacitor C ｔ and termination inductor L ｔ It may be provided in the rectifier circuit 5.

[0047] Figure 5F is a circuit diagram showing an example configuration of a load-independent inverse E-class inverter circuit 3F used in the electric field-coupled contactless power supply system shown in Figure 2. In Figure 5F, the inverter circuit 3F consists of: (1) an input inductor L Ｃ (2) a switching element Q which is, for example, an N-channel MOSFET, and (3) a shunt inductor L Ｓ and the shunt capacitor C (including the parasitic capacitance component of the switching element Q) Ｓ (4) Shunt capacitor and external capacitor C ｔ and termination inductor L ｔ It is composed of including and .

[0048] The inverter circuit 3F configured as described above receives the DC voltage V from the DC power supply 8. Ｉ A predetermined switching gate control voltage v ｇｓ By using this switching mechanism, a constant current flows through the load 7 or a constant voltage is maintained, and ZCS or ZVS is performed, regardless of the resistance value of the load 7.

[0049] The inverter circuit shown above is just one example; half-bridge and full-bridge inverters can also be used, regardless of whether they have load-independent characteristics or not.

[0050] (Rectifier circuit used in the embodiment) The rectifier circuit used in the embodiment is described below.

[0051] Figure 6A is a circuit diagram showing an example configuration of a half-bridge current-driven Class D rectifier circuit 5A used in the electric field-coupled contactless power supply system shown in Figure 2. In Figure 6A, the rectifier circuit 5A consists of: (1) Inductor L ｒ and capacitor C ｒ (2) Diode D １ , D ２ (3) A half-bridge rectifier including (3) a smoothing capacitor C ｆ It is composed of including and .

[0052] The rectifier circuit 5A configured as described above rectifies and smooths the AC voltage from the power transmission / reception pad section 4, and then applies the rectified and smoothed DC voltage to, for example, a load resistor R Ｌ Output to load 7.

[0053] Figure 6B is a circuit diagram showing an example configuration of a full-bridge current-driven Class D rectifier circuit 5B used in the electric field-coupled contactless power supply system of Figure 2. In Figure 6B, the rectifier circuit 5B consists of: (1) Inductor L ｒ and capacitor C ｒ (2) Diode D １ ~D ４ (3) A full-bridge rectifier including (3) a smoothing capacitor C ｆ It is composed of including and .

[0054] The rectifier circuit 5B configured as described above rectifies and smooths the AC voltage from the power transmission / reception pad section 4, and then applies the rectified and smoothed DC voltage to, for example, a load resistor R Ｌ Output to load 7.

[0055] Figure 6C is a circuit diagram showing an example configuration of a half-bridge voltage-driven Class D rectifier circuit 5C used in the electric field-coupled contactless power supply system shown in Figure 2. In Figure 6C, the rectifier circuit 5C consists of: (1) Inductor L ｒ and capacitor C ｒ (2) Diode D １ , D ２ (3) A half-bridge rectifier including a smoothing inductor L ｆ and smoothing capacitor C ｆ It is composed of a smoothing circuit including and .

[0056] The rectifier circuit 5C configured as described above rectifies and smooths the AC voltage from the power transmission / reception pad section 4, and then applies the rectified and smoothed DC voltage to, for example, a load resistor R Ｌ Output to load 7.

[0057] Figure 6D is a circuit diagram showing an example configuration of a full-bridge voltage-driven Class D rectifier circuit 5D used in the electric field-coupled contactless power supply system shown in Figure 2. In Figure 6D, the rectifier circuit 5D consists of: (1) Inductor L ｒ and capacitor C ｒ (2) Diode D １ ~D ４ (3) A full-bridge rectifier including a smoothing inductor L ｆ and smoothing capacitor C ｆ It is composed of a smoothing circuit including and .

[0058] The rectifier circuit 5D configured as described above rectifies and smooths the AC voltage from the power transmission / reception pad section 4, and then applies the rectified and smoothed DC voltage to, for example, a load resistor R Ｌ Output to load 7.

[0059] Figure 6E is a circuit diagram showing an example configuration of a load-independent Class E rectifier circuit 5E used in the electric field-coupled contactless power supply system shown in Figure 2. In Figure 6E, the rectifier circuit 5E consists of: (1) an inductor L ｒ and capacitor C ｒ (2) A shunt capacitor C Ｓ (3) For example, a switching element Q which is an N-channel MOSFET ３ (4) Smoothing inductor L Ｃ and smoothing capacitor C ｆ A smoothing circuit including (5) a predetermined switching gate control voltage v ｇｓａ It is composed of a control circuit 11 that generates and

[0060] The rectifier circuit 5E configured as described above receives the AC voltage from the power transmission / reception pad section 4 via the inductor L ｒ and capacitor C ｒ Switching element Q via an LC resonant circuit including ３Therefore, the switching gate control voltage v ｇｓａ After converting to a predetermined AC voltage by switching using a smoothing inductor L Ｃ and smoothing capacitor C ｆ The smoothing circuit, which includes the above, smooths the DC voltage to a predetermined DC voltage, and the smoothed DC voltage is then connected to, for example, a load resistor R Ｌ Output to load 7.

[0061] Figure 6F is a circuit diagram showing an example configuration of a load-independent E / F class rectifier circuit 5F used in the electric field-coupled contactless power supply system shown in Figure 2. In Figure 6F, the rectifier circuit 5F consists of: (1) Inductor L ｒ , L ２ and capacitor C ｒ , C ２ (2) A shunt capacitor C Ｓ (3) For example, a switching element Q which is an N-channel MOSFET ３ (4) Smoothing inductor L Ｃ and smoothing capacitor C ｆ A smoothing circuit including (5) a predetermined switching gate control voltage v ｇｓａ It is composed of a control circuit 11 that generates and

[0062] The rectifier circuit 5F configured as described above receives the AC voltage from the power transmission / reception pad section 4 and switches it through the LC resonant circuit to the switching element Q ３ Therefore, the switching gate control voltage v ｇｓａ After converting to a predetermined AC voltage by switching using a smoothing inductor L Ｃ and smoothing capacitor C ｆ The smoothing circuit, which includes the above, smooths the DC voltage to a predetermined DC voltage, and the smoothed DC voltage is then connected to, for example, a load resistor R Ｌ Output to load 7.

[0063] (Effects of the Embodiment) According to the above embodiment, a large coupling capacitor C is coupled in series with the capacitor of the resonant circuit. ｔThis was inserted. As a result, the output characteristics become constant regardless of the misalignment between the electrodes of the transmitting and receiving pad section 4 (constant output voltage or constant output voltage), and ZVS or ZCS can be achieved. Furthermore, by combining this with an inverter circuit having load-independent characteristics, both load-independent characteristics and characteristics independent of misalignment can be achieved. From the above, it is possible to achieve constant output characteristics and ZVS or ZCS (hereinafter, both together are referred to as "load-independent characteristics") with respect to misalignment between the electrodes of the transmitting and receiving pad section 4 and load fluctuations without complicating the control wireless communication line or power transmission circuit.

[0064] (Modified Example) In the above embodiment, the capacitance value C of the external capacitor is ｔ This is the capacitance value C of the capacitor between the electrodes. ｐ Preferably, it is set to be sufficiently small so that it becomes smaller, but the present invention is not limited to this, and may be configured so that the capacity value is not set. That is, the capacity value C ｐ and C ｔ The relative magnitudes of the two values ​​do not need to be a constraint. Here, the capacitance value C of the external capacitor. ｔ The impedance is sufficiently low at the driving frequency, and it is configured to block DC voltages. Furthermore, it does not require, for example, the insertion of an external capacitor.

[0065] Furthermore, considering the practical applications of electric field-coupled contactless power supply systems, it is necessary to maintain constant output characteristics (voltage or current) and high efficiency regardless of misalignment of the coupling capacitor (transmitting / receiving pad) or load fluctuations (changes due to battery level or charging). To achieve these, control feedback (transmitting information from the receiving device to the transmitting device) has generally been used. However, this method has challenges such as circuit complexity and delays associated with communication control. Therefore, load-independent design, which does not require a control system between the receiving and transmitting devices, is attracting attention. In this design method, load-independent operation is achieved by tuning the element values ​​to meet the load-independent conditions.

[0066] In the above embodiments, the circuit is not more complex than in the prior art, and the output voltage or output current is kept constant in response to misalignment between the electrodes of the transmitting and receiving pads and modulation of the load, while maintaining soft switching of ZVS or ZCS. However, the present invention is not limited to these embodiments, and load independence does not need to be achieved. The circuit is not more complex than in the prior art, and the output voltage or output current is kept constant in response only to misalignment between the electrodes of the transmitting and receiving pads, while maintaining soft switching of ZVS or ZCS. Therefore, load independence is optional.

[0067] As described in detail above, the present invention provides an electric field-coupled non-contact power supply system that, compared to the prior art, does not require a complex circuit, maintains a constant output voltage or output current despite misalignment between electrodes in the power transmission and reception pad section, and maintains soft switching of ZVS or ZCS.

[0068] 1. AC power supply 2. Power factor correction circuit (PFC circuit) 3. Inverter circuit 4. Power transmission / reception pad section 5. Rectifier circuit 6. DC-DC converter circuit 7. Load 8. DC power supply 10, 11. Control circuit 100, 100A Power transmission device 200, 200A Power receiving device C ０ , C １ , C ２ , C ２ａ , C ３ , C ｆ , C ｈ , C ｐ１ , C ｐ２ , C ｒ , C Ｓ , C Ｓａ , C ｔ Capacitors D1-D4, Diode L １ , L ２ , L ２ａ , L ３ , L Ｃ , L ｆ , L Ｉ , L Ｉａ , L ｒ , L ｔ , L ｈ Inductor Q, Q １ Q ２， Q ３ Switching element RＬ resistance

Claims

1. An electric field-coupled contactless power supply system in which a power transmitting device and a power receiving device are capacitively coupled via first and second electrodes of a power transmitting / receiving pad section, wherein the power transmitting device includes an inverter circuit including an external capacitor that converts a DC voltage into an AC voltage by switching and outputs it to the first electrode via the external capacitor, and the first electrode, and the power receiving device includes the second electrode and a rectifier circuit that converts the AC voltage received via the second electrode into a DC voltage and outputs it to a load, wherein the inverter circuit ensures that the output voltage or output current output to the load is constant and the DC voltage is zero-voltage switching (ZVS) or zero-current switching (ZCS), and the capacitance value of the external capacitor is set to be smaller than the capacitance value of the capacitor between the first and second electrodes.

2. The electric field coupled non-contact power supply system according to claim 1, wherein the inverter circuit further ensures that the output voltage or output current output to the load is constant and that the DC voltage is zero-voltage switching (ZVS) or zero-current switching (ZCS) independent of the resistance value of the load.

3. The electric field coupled non-contact power supply system according to claim 1 or 2, wherein, instead of the inverter circuit comprising the external capacitor, the rectifier circuit converts the AC voltage received via the second electrode and the external capacitor into a DC voltage and outputs it to the load.

4. The electric field coupled non-contact power supply system according to claim 1 or 2, wherein the first and second electrodes include two pairs of electrode pairs, the two pairs of electrode pairs include first and second capacitors, and the first and second capacitors are connected in series with each other.

5. The electric field coupled non-contact power supply system according to claim 1 or 2, wherein the power transmission device further comprises a power factor correction circuit provided upstream of the inverter circuit and converting an AC voltage to a DC voltage, and the power receiving device further comprises a DC-DC converter circuit provided between the rectifier circuit and the load and converting a DC voltage from the rectifier circuit to a predetermined DC voltage.

6. The ratio of the capacitance value of the capacitor between the first and second electrodes to the capacitance value of the external capacitor is 2.5 to 5, according to claim 1 or 2, for the field-coupled non-contact power supply system.

7. The ratio of the capacitance value of the capacitor between the first and second electrodes to the capacitance value of the external capacitor is 6 to 20, according to claim 1 or 2.

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