Wireless charging system and method for an electric vehicle

Abstract

A wireless charging system for charging an electric vehicle, comprising: a charging station comprising: an AC power source arranged to provide an AC voltage, and AC-DC converter arranged to convert the AC voltage to a primary DC voltage, a high-frequency inverter arranged to invert the primary DC voltage to a primary high-frequency AC voltage, and a transmitter coil arranged to receive the primary high-frequency AC voltage; and an EV charger unit arranged to be attached to the electric vehicle comprising: a receiver coil, said transmitter coil arranged to transfer power to the receiver coil via inductive coupling and generate a secondary high-frequency AC voltage in the receiver coil.

Description

[0001] WIRELESS CHARGING SYSTEM AND METHOD FOR AN ELECTRIC

[0002] VEHICLE

[0003] Field of Invention

[0004] The invention relates to the charging of electric vehicles, including, but not limited to e- bikes, e-scooters and electric cars.

[0005] Background

[0006] With the ongoing global push towards the transition to achieve Net Zero Carbon Emission, electric vehicles (EVs) will be omnipresent. The increasing popularity of electric vehicles (EVs) has brought about the need for efficient and high-power factor battery charging systems.

[0007] However, there are several issues with the present battery charging systems for EVs, including poor power efficiency, lengthy charging periods, and restricted mobility and compatibility, which makes them inconvenient to use. Conventional and typical EVs charging system uses physical wired connection to the loads. Thus, it may lead to limited flexibility in terms of location and mobility for charging. Additionally, the need for a physical connection and the time required for charging can be inconvenient for EVs owners.

[0008] Other than inconvenient and flexibility issues, there are several potential issues that could arise with the wired connected to the battery charging system for an EVs as follows: a) Low power factor

[0009] • the typical battery charger system for EVs does not include power factor correction features thus, the low power factor results in the charger consuming more power than necessary, leading to decreased efficiency and increased energy costs. Furthermore, it is difficult to meet regulatory requirements due to the low power factor. b) Limited mobility

[0010] • Typical EVs use wire connected must be parked close to the charger and connected to it via the cable to charge the battery. This limits the user's ability to move the EVs around while it is charging. A wire-connected battery charger is a type of charger that is connected to the battery through wires. The main problem with this type of charger is that the wires can become tangled or damaged over time, which can affect the charging process and potentially damage the battery or charger. Additionally, the user has to connect and disconnect the cable each time they want to charge the EVs, which can be time-consuming and inconvenient. c) Potential safety hazard

[0011] • Running a charging cable across a floor or other walkway can be a tripping hazard. d) Limited compatibility

[0012] • Some EVs may have proprietary charging ports that can only be used with specific chargers, limiting the user's ability to charge their EVs with any available charger. e) Safety

[0013] There are several potential safety issues that should be considered when designing a battery charging system for an EVs:

[0014] • Overcharging: It is important to prevent the battery from being charged beyond its capacity, as this can cause the battery to overheat and potentially ignite.

[0015] • Short circuit: The charging system should be designed to prevent short circuits, which can lead to overheating and potentially cause a fire.

[0016] User error: The charging system should be designed with user-error in mind and should include appropriate safeguards to prevent accidents caused by incorrect use. f) Energy saving

[0017] Implementation of power-saving features could include features such as a sleep mode or automatic cut-off when the battery is fully charged, to minimize energy consumption. When the charging system is not actively charging the battery, it could enter a low-power standby mode to reduce energy consumption. g) Real-Time Monitoring

[0018] Typical battery charger system only displays the level of the battery at the charging system. This could limit the access of charging operation status if the user is away from the charging station.

[0019] Summary of Invention

[0020] In a first aspect, the invention provides a wireless charging system for charging an electric vehicle, comprising: a charging station comprising; an AC power source arranged to provide an AC voltage; an AC-DC converter arranged to convert the AC voltage to a primary DC voltage; a high-frequency inverter arranged to invert the primary DC voltage to a primary high-frequency AC voltage; and; a transmitter coil, arranged to receive the primary high-frequency AC voltage; and; an EV charger unit arranged to be attached to the electric vehicle comprising: a receiver coil, said transmitter coil arranged to transfer power to the receiver coil via inductive coupling and generate a secondary high-frequency AC voltage in the receiver coil.

[0021] In a second aspect, the invention provides a charging station for charging an electric vehicle, comprising: an AC power source arranged to provide an AC voltage; an AC- DC converter arranged to convert the AC voltage to a primary DC voltage; a high- frequency inverter arranged to invert the primary DC voltage to a primary high- frequency AC voltage; and; a transmitter coil, arranged to receive the primary high- frequency AC voltage, and; wherein the AC-DC converter is integrated with a power factor correction module

[0022] In one embodiment, the invention may provide a high efficiency of wireless power transfer between transmitter and receiver coil.

[0023] In a further embodiment, the invention may provide a high power factor to the wireless charging system.

[0024] By way of a non-limiting example, 1.54% of Total Harmonic Distortion (THD) for the wireless charger system and complied with IEEE519:2022 Standard which maximum at

[0025] 8%. Brief Description of Drawings

[0026] It will be convenient to further describe the present invention with respect to the accompanying drawings that illustrate possible arrangements of the invention. Other arrangements of the invention are possible, and consequently the particularity of the accompanying drawings is not to be understood as superseding the generality of the preceding description of the invention.

[0027] Figure 1 is a schematic view of an electric vehicle coupling to a charging station unit according to one embodiment of the present invention;

[0028] Figures 2A to 2C are various views of a movable charging platform according to one embodiment of the present invention;

[0029] Figures 3A to 3C are various views of a movable charging platform according to one embodiment of the present invention, and;

[0030] Figure 4 is an elevation view of a GUI for a control app for a system according to the present invention.

[0031] Detailed Description

[0032] Referring to Figure 1, a wireless charging system 100 for an electric vehicle (EV), such as electric bike (E-bike), electric car (E-car), electric scooter (E-scooter) and the like, is provided. The wireless charging system 100 comprises a charging station 200 and an EV charger unit 300. The EV charger unit is arranged to be attached on the electric vehicle. The charging station 200 comprises an alternating current (AC) power source 5 arranged to provide an AC voltage. An AC-DC converter 10 is arranged to convert the AC voltage to a primary direct current (DC) voltage. The AC-DC converter 10 is integrated with a power factor correction (PFC) module to improve the power factor of the wireless charging system 100. A high-frequency inverter 15 is arranged to invert the primary DC voltage to a primary high-frequency AC voltage. The primary high- frequency AC voltage causes a transmitter coil 25 of the charging station 200 to generate an oscillating magnetic field such that power can be wirelessly transferred to a receiver coil 30 of the EV charger unit 300 via inductive coupling. The charging station 200 further comprises a primary resonance compensation module 20 arranged to compensate for inductance variations of the charger station so as to maintain the same resonant frequency between the charging station 200 and the EV charger unit 300 such that the inductive coupling and power transfer may be optimized.

[0033] The oscillating magnetic field induces a secondary high-frequency AC voltage in the receiver coil 30 of the EV charger unit 300. The EV charger unit 300 comprises a secondary resonance compensation module 35 arranged to compensate for inductance variations of the EV charger unit 300. Further, the EV charger unit 300 comprises a high-frequency rectifier 40 to convert the secondary high-frequency AC voltage to a secondary DC voltage. The EV charger unit 300 is further provided with a charging controller 45 to control the charging parameters, such as the charging voltage and the charging current of the battery 50 of the EV. The charging controller 45 may prevent overcharging of the battery, short circuit and user error. The charging controller 45 may enter into a sleep mode or automatically cut off the charging process when the battery is fully charged so as to save energy.

[0034] For the conventional wired charging system, the user’s ability to move the EV around while charging is limited. The wires of the convention charging system can be tangled or damaged overtime, which negatively affects the charging process and potentially damages the battery or charger. Additionally, the user has to connect and disconnect the wire every time when charging the EVs, which is time-consuming and inconvenient. Further, the wire of the wired charging system can be a tripping hazard. In addition, the wired charging system may only be used with specific types of EVs having compatible charging ports with the wired charger, which limits the user’s ability to charge the EV with any available charger. In contrast, the wireless charging system 100 due to its wireless nature enables enhanced mobility of the EV while charging and eliminates the risk as a tripping hazard. The wireless charging system 100 also obviates the risk of user error as user manually plugging in the wire to charge an EV is not required. Further, the wireless charging system 100 has no compatibility difficulties with charging ports as any wireless charging receiver is allowed to be coupled with the charging station 200.

[0035] Referring to Table 1, in operation, a rated charging current of 3 A may be achieved with high power factor by the wireless charging system 100, thus the wireless charging system 100 has a better performance in terms of charging time, which is 26 minutes faster than a wire-connected battery wireless charging system. The wire-connected battery charger uses a battery charging system in an EV provided by a manufacturer (Model: CHR-48V / LI, STonBike). An active power filter (APF) may be implemented together with the power factor correction module, such that the power factor of the wireless charging system 100 may be up to 0.94.

[0036] In one embodiment, referring to Figures 2A-2C, the charging station 200 may comprise a movable platform 60. The movable platform 60 enables the charging station 200 to move along at least one principal axis (XYZ-axes) in space, so as to align the charging station 200 towards the EV charger unit 300 at an optimal charging position 80 to maximize the charging efficiency and power factor. Figures 2A-2B show that the movable platform 60 may move along an x-axis or y-axis from the initial position to different positions 70, 75, such that the movable platform 60 may move freely in a horizontal plane. Further, Figure 2C shows that the movable platform 60 may move along a z-axis such that the movable platform 60 may move freely vertically. Once an EV 55 is present at the charging station 200, the movable platform 60 will be automatically activated by a processor and the charging station 200 will move to the optimal charging position 80 against the EV charger unit 300.

[0037] Different models of EVs may have different optimal charging positions 80 in space associated with the charging station 200. Referring to Figures 3A-3B, the movable platform 60 may comprise a moving mechanism such that the movable platform 60 first carries out an automated coarse movement based on the model of the EV to swiftly move directly from the initial position 160 to a secondary initial position 170 within a sub-area 185 close to the optimal charging position 80. The automated coarse movement may comprise a displacement from the initial position 160 to the secondary initial position 170 within a horizontal plane or x-y plane. The coarse movement may further comprise a displacement vertically or along z-axis. Then, the movable platform 60 starts a fine movement within the sub-area 185 to locate the charging station 200 at the optimal charging position 80 against the EV charger unit 300. The fine movement may start with a scanning within the horizontal plane or x-y plane and scans vertically to locate the optimal charging position 80. For example, the movable platform 60 may scan along x-axis with a predetermined increment along y-axis until a preliminary optimal position within the horizontal plane is located, as shown in Figure 3C. The other suitable types of scanning path such as sinusoidal, circular scanning path, and the like may also be implemented to locate the preliminary optimal position within the horizontal plane. Once the preliminary optimal position within the horizontal plane is located, the movable platform 60 may scan along the vertical direction or z-axis to locate the optimal charging position 80. The sub-area 170 is smaller than the total surface area of the EV 55but sufficiently large to cover the optimal charging position 80. The moving mechanism having the coarse movement and fine movement reduces the time to locate the charging station 200 at the optimal charging position 80 for each model of EVs 55, and thus enhance the overall charging efficiency.

[0038] The EV charger unit may comprises a battery voltage sensor arranged to measure the EV’s battery voltage level in real time. The measured battery voltage level is then processed using a processor or microcontroller, such as an Arduino Nano microcontroller. The processor sends data of the battery voltage level to the charging station via a wireless communication module, such as a Bluetooth HC-12.

[0039] The EV charger unit 300 may comprise a wireless communication module Bluetooth HC-12, which is connected to an Arduino Nano microcontroller via pins TX to pin D9 and RX to pin D8. The Arduino pin AO of the Arduino Nano microcontroller is connected to a voltage divider circuit to ensure a voltage input limited to 5V. The Vcc power supply of the Bluetooth HC-12 is connected to a 5 V power supply, and its pin GND is connected to the 5V power supply's ground. The input of the voltage divider circuit is connected to the battery 50 of the EV 55.

[0040] The charging station 200 may comprise a RF module, such as HC-12, and a processor or microcontroller, such as Arduino Pro Mini, Arduino Nano. The RF module is connected to the processor such that the processor may process data received by the RF module and / or send data to external wireless communication modules via the RF module. The data may be sent through serial communication. Particularly, the pin OUT of the RF module is connected to pin D3 of Arduino Pro Mini. An EV sensor module is provided to automatically detect the presence of the EV and send a signal to the processor or microcontroller. The EV sensor module may comprise an infrared module having an infrared sensor.

[0041] The EV sensor module may have two LEDs to display an ID status indicating whether an EV is present. Particularly, the two LEDs are connected to pins D12 and D13 of the Arduino Pro Mini. The circuit of the charging station further comprises a solid state relay to automatically switch on or off a power supply to the charging station from the AC power source. An display module, such as an LCD display, LED display, or OLED display, may be provided to display the battery voltage level in real time.

[0042] The EV charger unit 300 may comprise a charging monitoring system having a sensor to monitor the battery’s charging status, such as percentage, voltage level, charging or discharging status, in real-time. The battery’s percentage, voltage level, charging or discharging status may be processed using a processor or microcontroller, such as an Arduino Nano microcontroller. A wireless connection module may be used to connect the charging monitoring system over a wireless medium. The wireless connection module may comprise a Wi-Fi connection or Bluetooth connection. The processor may be arranged to send the data comprising the battery’s percentage, voltage level, charging or discharging status to a mobile device, such as a mobile phone, tablet, or smart watch, via the wireless connection module. Serial communication may be applied to communicate from the processor to the mobile device.

[0043] A mobile dashboard may be created in the mobile device by turning ON a development mode by selecting a template created on a mobile application, such as Blynk loT Apps. The charging monitoring system comprises a development board, such as ESP32, which is linked to the template via wireless communication, and thus initiating the development of the charging monitoring system. Desired functions of the charging monitoring system may be enhanced by dragging and pasting available widgets on the interface of the Blynk loT Apps. The available widgets in Blynk loT Apps comprise a controller widget, a display widget, and interface widgets that allow users to write an input into the charging monitoring system wirelessly. A gauge widget, super chart widget, and value display widget may be applied in the charging monitoring system. An exemplary mobile dashboard of the charging monitoring system is shown in Figure 4, which displays the charging percentage, voltage reading, and the trend of charging percentage.

Claims

We claim:

1. A wireless charging system for charging an electric vehicle, comprising: a charging station comprising: an AC power source arranged to provide an AC voltage; an AC-DC converter arranged to convert the AC voltage to a primary DC voltage; a high-frequency inverter arranged to invert the primary DC voltage to a primary high-frequency AC voltage, and; a transmitter coil, arranged to receive the primary high-frequency AC voltage, and; an EV charger unit arranged to be attached to the electric vehicle comprising: a receiver coil, said transmitter coil arranged to transfer power to the receiver coil via inductive coupling and generate a secondary high-frequency AC voltage in the receiver coil.

2. The wireless charging system according to claim 1, further comprising a movable platform movable along at least one of XYZ-axes, arranged to align the charging station towards the EV charger unit at an optimal charging position.

3. The wireless charging system according to claim 2, wherein said movable platform comprises: a moving mechanism that the movable platform is arranged to perform an automated coarse movement based on a model of the electric vehicle; such that the automated coarse movement includes the movable platform is arranged to move from an initial position to a secondary initial position within a sub-area close to the optimal charging position; the automated coarse movement further including the movable platform being arranged to move within the sub-area to locate the charging station at the optimal charging position; said sub-area configured to be smaller than a total surface area of the electric vehicle.

4. The wireless charging system according to any one of the preceding claims, wherein the EV charger unit further comprises a charging monitoring system having a sensor arranged to monitor a charging status of a battery of the electric vehicle in real-time.

5. The wireless charging system according to any one of the preceding claims, wherein the EV charger unit further comprises a high-frequency rectifier arranged to convert the secondary high-frequency AC voltage to a secondary DC voltage.

6. The wireless charging system according to any one of the preceding claims, wherein the charger station further comprises a primary resonance compensation module arranged to compensate for inductance variations.

7. The wireless charging system according to any one of the preceding claims, wherein the EV charger unit further comprises a secondary resonance compensation module arranged to compensate for inductance variations of the EV charger unit.

8. The wireless charging system according to any one of the preceding claims, wherein the EV charger unit further comprises a charging controller arranged to control the charging parameters of the battery.

9. A charging station for charging an electric vehicle, comprising: an AC power source arranged to provide an AC voltage; an AC-DC converter arranged to convert the AC voltage to a primary DC voltage; a high-frequency inverter arranged to invert the primary DC voltage to a primary high-frequency AC voltage, and; a transmitter coil, arranged to receive the primary high-frequency AC voltage, and; wherein the AC-DC converter is integrated with a power factor correction module.

10. The charging station according claim 9, further comprising an active power filter arranged to be implemented together with the power factor correction module.

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