Method and system for protecting wireless power transmission systems

Abstract

We provide wireless power transmission systems. [Solution] The wireless power transmission system includes a first conversion unit configured to convert a first DC voltage of input power to a first AC voltage. Furthermore, the wireless power transmission system includes a non-contact power transmission unit configured to receive input power having a first AC voltage from the first conversion unit and transmit the input power. The wireless power transmission system also includes a second conversion unit configured to receive input power from the non-contact power transmission unit and convert the first AC voltage of the input power to a second DC voltage. Furthermore, the wireless power transmission system includes a switching unit configured to adjust the second DC voltage between the ends of an electrical load if the second DC voltage between the ends of the electrical load is greater than a voltage reference value.

Description

Technical Field

[0001] Embodiments of the present invention generally relate to wireless power transmission systems, and more particularly to systems and methods for protecting wireless power transmission systems.

Background Art

[0002] In one or more industries, electric vehicles or hybrid vehicles include one or more batteries that supply power to drive the vehicle. In one example, the battery supplies energy to an electric motor to drive an axle within the vehicle, and thereby the vehicle is driven. The battery is used to supply power and thus may deplete and needs to be charged from an external power source.

[0003] Generally, power transmission systems are widely used to transmit power from a power source to one or more electrical loads, such as a battery within a vehicle. Typically, the power transmission system can be a contact-based power transmission system or a non-contact power transmission system. In a contact-based power transmission system, components such as plugs, socket connectors, and electrical wires are physically coupled to the battery to charge the battery. However, due to environmental effects, such connectors and electrical wires may be damaged or corroded. Also, high current and high voltage are used to charge the battery. Thus, establishing a physical connection between the power source and the battery within the vehicle may involve cumbersome safety measures. Also, this power transmission system may be bulkier and heavier compared to a non-contact power transmission system.

[0004] In contactless power transmission systems, power converters are used to convert input power into transmittable power that can be further transmitted to an electrical load, such as a battery in a vehicle. Power converters include switches that operate at a specific switching frequency to convert input power into transmittable power. Typically, depending on the load, the switching frequency of the power converter is changed to adjust or control the output voltage of the power transmission system. However, if the electrical load is disconnected or changed, the output voltage of the power transmission system can reach very high values ​​in a very short time. Such a sudden increase in output voltage can lead to operational failure and may damage one or more components in the power transmission system.

[0005] Therefore, improvements to systems and methods for protecting power transmission systems are needed. [Overview of the Initiative] [Means for solving the problem]

[0006] One embodiment of the present invention discloses a wireless power transmission system. The wireless power transmission system includes a first conversion unit configured to convert a first DC voltage of input power to a first AC voltage. Furthermore, the wireless power transmission system includes a contactless power transmission unit, which is communicatively coupled to the first conversion unit and configured to receive input power having a first AC voltage from the first conversion unit and transmit the input power. The wireless power transmission system also includes a second conversion unit, which is communicatively coupled to the contactless power transmission unit and configured to receive input power from the contactless power transmission unit and convert the first AC voltage of the input power to a second DC voltage. The input power having the second DC voltage is transmitted to an electrical load. Furthermore, the wireless power transmission system includes a switching unit coupled to the contactless power transmission unit and the second conversion unit and configured to adjust the second DC voltage across the electrical load if the second DC voltage across the electrical load is greater than a voltage reference value.

[0007] According to another embodiment of the present invention, a switching unit for protecting a wireless power transmission system is disclosed. The switching unit includes a switch configured to be electrically coupled between the ends of a second conversion unit. The second conversion unit is configured to be coupled to an electrical load. The switching unit also includes a controller configured to be electrically coupled to the switch and to generate and supply a control signal having a determined due cycle to regulate the output DC voltage between the ends of the electrical load.

[0008] Another embodiment of the present invention discloses a method for protecting a wireless power transmission system. The method includes the step of converting a first DC voltage of input power to a first AC voltage using a first conversion unit. The method further includes the step of receiving input power having the first AC voltage from the first conversion unit and transmitting it using a contactless power transmission unit. The method also includes the step of converting the first AC voltage of input power to a second DC voltage using a second conversion unit. The method further includes the step of transmitting input power having the second DC voltage from the second conversion unit to an electrical load. The method further includes the step of adjusting the second DC voltage across the electrical load using a switching unit if the second DC voltage across the electrical load is greater than a voltage reference value.

[0009] These and other features, aspects, and advantages of this disclosure will be better understood by reading the following detailed description with reference to the attached drawings, where the same letters throughout the drawings represent the same parts. [Brief explanation of the drawing]

[0010] [Figure 1] This is a configuration diagram showing a wireless power transmission system having a switching unit according to an embodiment of the present invention. [Figure 2] This is a circuit diagram of a wireless power transmission system according to an embodiment of the present invention. [Figure 3]This is a circuit diagram of a wireless power transmission system according to another embodiment of the present invention. [Figure 4] This flowchart illustrates an example of a method for protecting a wireless power transmission system according to an embodiment of the present invention. [Figure 5] This flowchart illustrates a method for decoupled and coupled conversion units in a wireless power transmission system according to an embodiment of the present invention. [Figure 6] This flowchart illustrates a method for adjusting the output voltage of a wireless power transmission system according to an embodiment of the present invention. [Modes for carrying out the invention]

[0011] Various embodiments of systems and methods for protecting wireless power transmission systems are disclosed below, as will be described in detail below. Also disclosed are various embodiments of systems and methods for regulating the output voltage of wireless power transmission systems. Specifically, the systems and methods disclosed herein employ a switching unit to protect one or more components within a wireless power transmission system. More specifically, the switching unit decouples one or more components within the system if the output voltage of the wireless power transmission system increases to an undesirable value. Furthermore, the switching unit can be used to control or regulate the output voltage of a wireless power transmission system even when the electrical load coupled to the wireless power transmission system changes significantly.

[0012] Figure 1 is a schematic representation of a wireless power transmission system 100 according to an embodiment of the present invention. The wireless power transmission system 100 is used to transmit power from a power source 102 to one or more electrical loads 132, such as batteries, light loads, mobile devices like mobile phones, laptop computers, and HVAC systems. In particular, in the automotive industry, electric vehicles or hybrid vehicles include one or more batteries that supply power to drive the vehicle. Such batteries can be charged from the power source 102 via the wireless power transmission system 100. In one embodiment, the wireless power transmission system 100 may also be referred to as a contactless power transmission system.

[0013] In an exemplary embodiment, the wireless power transmission system 100 includes a first conversion unit 104 (inverter), a control unit 106, a contactless power transmission unit 108, and a second conversion unit 110 (rectifier). The first conversion unit 104 is electrically coupled to a power supply 102 and the control unit 106. The power supply 102 is configured to supply input power having a first DC voltage 112 to the first conversion unit 104. In some embodiments, the input power can range from about 100 W to about 6.6 kW. In one embodiment, the power supply 102 can be part of the wireless power transmission system 100. In another embodiment, the power supply 102 can be located outside the wireless power transmission system 100.

[0014] The first conversion unit 104 is configured to receive input power having a first DC voltage 112 from the power supply 102. Furthermore, the first conversion unit 104 is configured to operate at a determined switching frequency in order to convert the first DC voltage 112 of the input power to a first AC voltage 114. In particular, the control unit 106 can determine the switching frequency of the first conversion unit 104 based on an electrical load 132 coupled to the wireless power transmission system 100. In one example, the control unit 106 may include a digital circuit or processor that performs one or more functions based on pre-stored instructions or programs. Once the first DC voltage 112 of the input power has been converted to the first AC voltage 114, the first conversion unit 104 is further configured to transmit the input power having the first AC voltage 114 to the contactless power transmission unit 108.

[0015] The contactless power transmission unit 108 includes two or more coils or an array of coils 116 that are magnetically coupled to each other. The coils 116 are used to wirelessly transmit input power having a first AC voltage 114 from the first conversion unit 104 to the second conversion unit 110. Details regarding the transmission of power using the coils 116 will be described in more detail below with reference to Figure 2.

[0016] The second conversion unit 110 is electrically coupled to the contactless power transmission unit 108 via the switching unit 130. Upon receiving power having a first AC voltage 114 from the contactless power transmission unit 108, the second conversion unit 110 is configured to convert the power having the first AC voltage 114 into output power having a second DC voltage 118. Furthermore, the second conversion unit 110 is configured to transmit the output power having the second DC voltage 118 to an electrical load 132. In one example, the output power can be used to charge an electrical load, including one or more batteries coupled to the wireless power transmission system 100.

[0017] Furthermore, the wireless power transmission system 100 includes a sensor 120, a first transceiver 122, and a second transceiver 124, together forming a feedback loop 126. The sensor 120 is used to sense a second DC voltage (output voltage) 118. The feedback loop 126 is used to communicate a voltage signal (Vo) 128 representing the second DC voltage 118 from the sensor 120 to the control unit 106 via the first transceiver 122 and the second transceiver 124. Furthermore, the control unit 106 can be used to adjust or change the switching frequency of the first conversion unit 104 based on the received voltage signal (Vo) 128 in order to control or regulate the second DC voltage 118 across the electrical load 132.

[0018] However, since the voltage signal (Vo) 128 is communicated using a wireless communication path between the first transceiver 122 and the second transceiver 124, the control unit 106 may receive the voltage signal (Vo) 128 after a certain time delay. In one embodiment, the delay can range from about 1 millisecond to about 5 milliseconds. The delay in communicating the voltage signal (Vo) 128 may prevent the control unit 106 from controlling the second DC voltage 118 across the electrical load 132 in a timely manner. As a result, the second DC voltage 118 may increase beyond a critical value, which may then damage the second converter unit 110 and / or other components in the wireless power transmission system 100. The critical value may be a voltage value beyond which components in the wireless power transmission system 100 may be damaged. In one embodiment, the critical value may range from about 400V to about 500V.

[0019] To overcome the problems associated with increasing the second DC voltage 118 beyond a critical value, the exemplary wireless power transmission system 100 includes a switching unit 130 to protect the second converter unit 110 from damage. In particular, the switching unit 130 is electrically coupled to the contactless power transmission unit 108 and the second converter unit 110. The switching unit 130 is configured to decouple the second converter unit 110 from the contactless power transmission unit 108 when the second DC voltage 118 is greater than a first threshold (VoMax). The first threshold (VoMax) may be less than a critical value. In one embodiment, the first threshold (VoMax) may be in the range of about 350V to about 450V.

[0020] The input power is not transmitted to the second converter unit 110 or the electrical load 132 by decoupling the second converter unit 110 from the contactless power transmission unit 108. As a result, the second DC voltage 118 across the electrical load 132 can be reduced to below the first threshold (VoMax). The switching unit 130 is configured to prevent the second DC voltage 118 from reaching a critical value, thereby protecting the second converter unit 110 from damage. The protection of the second converter unit 110 will be described in more detail with reference to Figure 2.

[0021] Furthermore, in one embodiment, the switching unit 130 can be used to adjust or control a second DC voltage 118 across the electrical load 132. If the second DC voltage 118 is greater than a voltage reference value (Voref), the switching unit 130 is configured to adjust or control the second DC voltage 118 without decoupling the second conversion unit 110 from the contactless power transmission unit 108. The adjustment of the second DC voltage 118 will be described in more detail with reference to Figure 3.

[0022] Referring to FIG. 2, a circuit diagram of a wireless power transmission system 200 according to an embodiment of the present invention is shown. The wireless power transmission system 200 is similar to the wireless power transmission system 100 of FIG. 1. The wireless power transmission system 200 is used to transmit input power from a power source 202 to an electrical load 232 such as one or more batteries in an electric vehicle or a hybrid vehicle.

[0023] The wireless power transmission system 200 includes a first conversion unit 204, a control unit 206, a non-contact power transmission unit 208, a second conversion unit 210, a switching unit 212, a first transceiver 214, and a second transceiver 216. It should be noted that the wireless power transmission system 200 can include other components and may not be limited to the components shown in FIG. 2.

[0024] In the illustrated embodiment, the first conversion unit 204 is electrically coupled to the power source 202 and is configured to receive input power having a first DC voltage 218 from the power source 202. The first conversion unit 204 includes a plurality of switches 220 and diodes 222 that are electrically coupled between the input terminal and the output terminal of the first conversion unit 204. In one example, the switch 220 can include an electronic switch such as a MOSFET or an IGBT. The plurality of switches 220 and diodes 222 are arranged to form a DC / AC converter.

[0025] Switch 220 is operated and deactivated based on the switching frequency of the first conversion unit 204 to convert the first DC voltage 218 of the input power to the first AC voltage 224. In particular, the control unit 206 is configured to determine the switching frequency of the first conversion unit 204 based on the electrical load 232 coupled to the wireless power transmission system 200. Furthermore, the control unit 206 is configured to send one or more gate signals 226 representing the switching frequency to a plurality of switches 220 to convert the first DC voltage 218 of the input power to the first AC voltage 224. The input power having the first AC voltage 224 is transmitted from the first conversion unit 204 to the contactless power transmission unit 208.

[0026] The contactless power transmission unit 208 is electrically coupled to the first conversion unit 204 to receive input power having a first AC voltage 224. The contactless power transmission unit 208 includes a primary coil 228 and a secondary coil 230. The primary coil 228 is electrically coupled to the first conversion unit 204. Similarly, the secondary coil 230 is electrically coupled to the second conversion unit 210. The primary coil 228 and the secondary coil 230 are magnetically coupled to each other.

[0027] The non-contact power transmission unit 208 includes a magnetic field focusing coil 234 and a compensation coil 236, in addition to the primary coil 228 and the secondary coil 230. The magnetic field focusing coil 234 is positioned between the primary coil 228 and the secondary coil 230. The magnetic field focusing coil 234 is magnetically coupled to the primary coil 228 and the secondary coil 230. Similarly, the compensation coil 236 is magnetically coupled to the secondary coil 230. It can be noted that the non-contact power transmission unit 208 may include two or more coils to transmit power from the first conversion unit 204 to the second conversion unit 210.

[0028] Furthermore, the input power having a first AC voltage 224 from the first conversion unit 204 is configured to simultaneously excite the primary coil 228 and the magnetic field focusing coil 234. The magnetic field generated by the primary coil 228 is focused toward the secondary coil 230 via the magnetic field focusing coil 234. The secondary coil 230 is configured to receive the magnetic field and convert it into input power having the first AC voltage 224. The power having the first AC voltage 224 is then transmitted from the secondary coil 230 to the second conversion unit 210. In one embodiment, the magnetic field focusing coil 234 is electrically coupled to one or more resonators arranged in an array that are simultaneously excited by the input power to enhance the coupling between the primary coil 228 and the secondary coil 230. A compensation coil 236 is configured to match the impedance of the non-contact power transmission unit 208 to that of the second conversion unit 210.

[0029] The second conversion unit 210 is configured to convert power having a first AC voltage 224 into output power having a second DC voltage 238. In particular, the second conversion unit 210 includes a plurality of diodes, MOSFETs, or IGBTs 240 electrically coupled between the input and output terminals of the second conversion unit 210. The power having the second DC voltage 238 is transmitted to an electrical load 232. In one embodiment, the electrical load 232 may be a battery that is charged by using the power received from the second conversion unit 210. It should be noted that the terms “output voltage” and “second DC voltage” can be used interchangeably in this specification.

[0030] Furthermore, the wireless power transmission system 200 includes a sensor 244, a first transceiver 214, and a second transceiver 216, together forming a feedback loop 242. The feedback loop 242 is used to communicate load information and / or second DC voltage information to a control unit 206. More specifically, the sensor 244 is electrically coupled to the output terminal of a second conversion unit 210 to determine a second DC voltage 238 across the electrical load 232. In one embodiment, the sensor 244 may be a voltage sensor. In such an embodiment, the sensor 244 is configured to transmit a voltage signal (Vo) 246 representing the determined second DC voltage 238 to the first transceiver 214.

[0031] The first transceiver 214 includes an antenna 248 configured to transmit a voltage signal (Vo) 246 toward the antenna 250 of the second transceiver 216. In one embodiment, the first transceiver 214 can be positioned in close proximity to an electrical load 232, and the second transceiver 216 can be positioned in close proximity to the first conversion unit 204 or power supply 202. The second transceiver 216 is configured to receive the voltage signal (Vo) 246 transmitted by the first transceiver 214. Furthermore, the second transceiver 216 is configured to transmit the received voltage signal (Vo) 246 to a control unit 206.

[0032] The control unit 206 is configured to determine changes in the electrical load 232 based on a voltage signal (Vo) 246 representing a second DC voltage 238. In response to receiving the voltage signal (Vo) 246, the control unit 206 is configured to determine or adjust the switching frequency of the first converter unit 204. Furthermore, the control unit 206 is configured to send a gate signal 226 representing the switching frequency to the first converter unit 204 to control the first AC voltage 224 of the first converter unit 204, thereby controlling the second DC voltage 238 across the electrical load 232. In other words, the control unit 206 is configured to control or adjust the second DC voltage 238 of the wireless power transmission system 200 based on the voltage signal (Vo) 246 received via the feedback loop 242.

[0033] Similar to the embodiment in Figure 1, to overcome the problems associated with increasing the second DC voltage 238 beyond a critical value, the exemplary wireless power transmission system 200 includes a switching unit 212 configured to protect the second conversion unit 210 from damage. The switching unit 212 includes a switch 252 and a controller 254. The controller 254 is electrically coupled to the switch 252 and the sensor 244.

[0034] In the exemplary embodiment, switch 252 is electrically coupled between the two ends of the second conversion unit 210. Switch 252 is activated when it receives a first control signal from controller 254. Specifically, switch 252 is activated or closed to short-circuit the secondary coil 230, thereby decoupled the second conversion unit 210 from the secondary coil 230. Similarly, switch 252 may be deactivated when it receives a second control signal from controller 254. Specifically, switch 252 is deactivated or opened to couple the secondary coil 230 to the second conversion unit 210.

[0035] The controller 254 includes a first comparator 256, a second comparator 258, and a flip-flop unit 260. The first comparator 256 and the second comparator 258 are electrically coupled to the input terminals of the flip-flop unit 260. The input terminals of the controller 254 are coupled to the first comparator 256 and the second comparator 258. The output terminals of the controller 254 are coupled to the flip-flop unit 260.

[0036] The controller 254 is configured to receive a voltage signal (Vo) 246 representing a second DC voltage 238 from the sensor 244. Furthermore, the received voltage signal (Vo) 246 is transmitted to the first comparator 256 and the second comparator 258. The first comparator 256 is configured to compare the second DC voltage 238 with a first threshold (VoMax). If the second DC voltage 238 is greater than the first threshold (VoMax), the first comparator 256 is configured to trigger a flip-flop unit 260 to generate a first control signal at the output terminal of the controller 254.

[0037] Similarly, the second comparator 258 is configured to receive a voltage signal (Vo) 246 representing a second DC voltage 238. Furthermore, the second comparator 258 is configured to compare the received second DC voltage 238 with a second threshold (VoMin). Note herein that the second threshold (VoMin) is smaller than the first threshold (VoMax). If the second DC voltage 238 is smaller than the second threshold (VoMin), the second comparator 258 is configured to trigger a flip-flop unit 260 to generate a second control signal at the output terminal of the controller 254.

[0038] During normal operation of the wireless power transmission system 200, switch 252 is deactivated to couple the second conversion unit 210 to the contactless power transmission unit 208. The second DC voltage 238 across the electrical load 232 is controlled or regulated by the control unit 206 based on the voltage signal (Vo) 246 received from the sensor 244 via the first transceiver 214 and the second transceiver 216. The controller 254 does not activate or close switch 252 if the second DC voltage 238 is less than a first threshold (VoMax).

[0039] In certain circumstances, if the entire load 232 or a portion of the load 232 is suddenly disconnected or decoupled from the second conversion unit 210, the second DC voltage 238 across the load 232 may increase beyond a first threshold (VoMax). Sensor 244 determines a voltage signal (Vo) 246 representing this second DC voltage 238 and sends it to controller 254 and first transceiver 214. In controller 254, first comparator 256 compares the second DC voltage 238 with the first threshold (VoMax). If the second DC voltage 238 is greater than the first threshold (VoMax), first comparator 256 generates a first control signal to be sent to switch 252, triggering flip-flop unit 260 to deactivate switch 252. As a result, the second conversion unit 210 is decoupled from contactless power transmission unit 208.

[0040] Simultaneously, the first control signal is transmitted from the controller 254 to the first transceiver 214. Furthermore, the first transceiver 214 transmits the voltage signal (Vo) 246 received from the sensor 244 and the first control signal received from the controller 254 to the second transceiver 216. The voltage signal (Vo) 246 and the first control signal are then transmitted to the control unit 206.

[0041] Upon receiving the voltage signal (Vo) 246 and the first control signal, the control unit 206 determines, based on the received first control signal, that switch 252 is activated in the wireless power transmission system 200. As a result, the control unit 206 deactivates the first conversion unit 204. In one embodiment, the control unit 206 sends a gate signal 226 to switch 220 in the first power conversion unit 204 to deactivate or open switch 220. As a result, the first conversion unit 204 is deactivated or interrupted from transmitting power to the contactless power transmission unit 208 and the second conversion unit 210.

[0042] Furthermore, after a predetermined time, the control unit 206 sends a reset signal 262 to the second transceiver 216, which further transmits the reset signal 262 to the first transceiver 214. The first transceiver 214 sends the reset signal 262 to the flip-flop unit 260 in the controller 254. In response to receiving the reset signal 262, the flip-flop unit 260 resets and generates a second control signal at the output terminal of the controller 254. The generated second control signal is transmitted to the switch 252 to deactivate or open the switch 252, and thus the second converter unit 210 is coupled to the contactless power transmission unit 208, enabling the second converter unit 210 to continuously supply power having a second DC voltage 238 to the electrical load 232.

[0043] Simultaneously, the second control signal generated in the controller 254 is transmitted to the first transceiver 214. In addition to the second control signal, the first transceiver 214 receives a voltage signal (Vo) 246 representing the second DC voltage 238 across the load 232. Furthermore, the first transceiver 214 transmits the voltage signal (Vo) 246 and the second control signal to the second transceiver 216, which then transmits these signals to the control unit 206.

[0044] Upon receiving the voltage signal (Vo) 246 and the second control signal from the second transceiver 216, the control unit 206 determines whether the second DC voltage 238 is less than or equal to the first threshold (VoMax). If the second DC voltage 238 is less than or equal to the first threshold (VoMax), the control unit 206 sends a gate signal 226 to the switch 220 in the first converter unit 204 to activate the first converter unit 204. Furthermore, the control unit 206 adjusts or changes the switching frequency of the first converter unit 204 based on the second DC voltage 238 across the electrical load 232. In one embodiment, the control unit 206 adjusts or changes the switching frequency of the first converter unit 204 to adjust or control the second DC voltage 238 across the electrical load 232. If the second DC voltage 238 is greater than the first threshold (VoMax), the control unit 206 waits for a predetermined time to send another reset signal to the controller 254. If the second DC voltage 238 remains greater than the first threshold (VoMax) after sending the reset signal a predetermined number of times, the control unit 206 shuts down the system 200.

[0045] Therefore, by employing the switching unit 212 and the control unit 206, the second DC voltage 238 is prevented from increasing beyond a critical value. As a result, the second conversion unit 210 is protected from damage even when the electrical load 232 is disconnected or decoupled from the wireless power transmission system 200.

[0046] Referring to Figure 3, a circuit diagram of a wireless power transmission system 300 according to another embodiment of the present invention. The wireless power transmission system 300 is similar to the wireless power transmission system 200 of Figure 2, except that a controller 302 in the switching unit 212 is configured to adjust or control the second DC voltage 238 (output voltage) of the second conversion unit 210.

[0047] During operation, if the electrical load 232 is disconnected from the wireless power system 300, the second DC voltage 238 across the load 232 may increase beyond a voltage reference value (Voref). It is necessary to control or regulate the second DC voltage 238 so that it does not increase beyond a critical value. In one example, the voltage reference value (Voref) is less than the critical value.

[0048] Sensor 244 determines a second DC voltage 238 across the electrical load 232. Furthermore, sensor 244 transmits a voltage signal (Vo) 246 representing the second DC voltage 238 to controller 302. In controller 302, the second DC voltage 238 is compared to a voltage reference value (Voref). If the second DC voltage 238 is greater than the voltage reference value (Voref), controller 302 generates a control signal 304 with the determined duty cycle to control switch 252. In one embodiment, controller 302 can determine or select the duty cycle using a lookup table. For example, if the second DC voltage 238 is 90 volts, a duty cycle of 0.75 corresponding to 90 volts is selected from the lookup table. In another example, if the second DC voltage 238 is 170 volts, a duty cycle of 0.5 corresponding to 170 volts is selected from the lookup table. In yet another example, if the second DC voltage 238 is 250 volts, a duty cycle of 0.25 corresponding to 250 volts is selected from the lookup table.

[0049] The controller 302 transmits a control signal 304 having a determined duty cycle to the switch 252 in order to adjust or control the second DC voltage 238 across the load 232. In particular, the control signal 304 has a switching pulse having a determined duty cycle. The switching pulse is transmitted to the switch 252 in order to adjust or control the second DC voltage 238 across the load 232.

[0050] Simultaneously, the voltage signal (Vo) 246 is transmitted from the sensor 244 to the first transceiver 214. Furthermore, the first transceiver 214 transmits the voltage signal (Vo) 246 to the second transceiver 216, and then the voltage signal (Vo) 246 is transmitted to the control unit 206.

[0051] In the control unit 206, a gate signal 226 is generated based on the second DC voltage 238. Furthermore, the control unit 206 transmits the gate signal 226 to a switch 220 in the first converter unit 204 to adjust or change the switching frequency of the first converter unit 204. As a result, the first AC voltage 224 from the first converter unit 204 is adjusted, and thereafter the second DC voltage 238 across the load 232 is controlled or adjusted. However, the adjustment of the second DC voltage 238 using the control unit 206 is performed after the adjustment of the second DC voltage using the controller 302. Therefore, the controller 302 can perform faster adjustment of the second DC voltage 238 compared to the adjustment of the second DC voltage 238 by the control unit 206.

[0052] Therefore, the second DC voltage 238 across the load 232 is adjusted or controlled by employing the switching unit 212 before the second DC voltage 238 reaches a critical value. As a result, the second conversion unit 210 is protected from damage even when the electrical load 232 is disconnected from the wireless power transmission system 300.

[0053] Referring to Figure 4, a flowchart illustrating a method 400 for protecting a wireless power transmission system according to an aspect of the present invention is shown. Method 400 will be described with reference to the components of Figures 1 and 2. In step 402, a first DC voltage of the input power is converted to a first AC voltage. A first conversion unit is coupled to a power supply to receive the input power having the first DC voltage. The first conversion unit operates at a determined switching frequency to convert the first DC voltage of the input power to the first AC voltage.

[0054] Next, in step 404, the method includes the steps of receiving and transmitting input power having a first AC voltage. In particular, a contactless power transmission unit is electrically coupled to a first converter unit to receive input power having a first AC voltage. The contactless power transmission unit transmits the input power having a first AC voltage to a second converter unit. Furthermore, in step 406, the first AC voltage of the input power is converted to a second DC voltage. The second converter unit is electrically coupled to a contactless power transmission unit to receive input power having a first AC voltage. Furthermore, the second converter unit converts the first AC voltage of the input power to a second DC voltage. In step 408, the input power having a second DC voltage is transmitted from the second converter unit to an electrical load. In one embodiment, the electrical load may be one or more batteries that are charged using the input power having a second DC voltage received from the second converter unit.

[0055] In step 410, the second conversion unit is decoupled from the contactless power transmission unit if the second DC voltage across the electrical load is greater than the first threshold (VoMax). Specifically, a switching unit is used to decouple the second conversion unit from the contactless power transmission unit. As a result, the second DC voltage across the electrical load is reduced to less than the first threshold (VoMax), thereby protecting the second conversion unit from overvoltage damage. Furthermore, if the determined second DC voltage is less than the second threshold (VoMin), the switching unit couples the second conversion unit to the contactless power transmission unit to continue supplying power with the second DC voltage to the electrical load.

[0056] Referring to Figure 5, a flowchart illustrating a method for decoupled and coupled a second conversion unit in a wireless power transmission system according to an embodiment of the present invention is shown. Specifically, method 500 includes the steps involved in step 410 of Figure 4. In step 502, a voltage signal (Vo) representing a second DC voltage across the electrical load is transmitted by the sensor. More specifically, the sensor transmits the voltage signal (Vo) to the controller. Furthermore, the sensor transmits the voltage signal (Vo) to the control unit via a first transceiver and a second transceiver.

[0057] Next, in step 504, the controller determines whether the voltage signal (Vo) representing the second DC voltage is greater than the first threshold (VoMax). If the voltage signal (Vo) representing the second DC voltage is greater than the first threshold (VoMax), the controller sends a first control signal to the switch to activate or close the switch, as shown in step 506. As a result, the second conversion unit is decoupled from the contactless power transmission unit, thereby reducing the second DC voltage across the load to below the first threshold (VoMax). More specifically, the second DC voltage is prevented from reaching a critical value greater than the first threshold (VoMax). The critical value may be a voltage value that, if exceeded, could damage the second conversion unit. Simultaneously, the controller sends a first control signal to the control unit via the first and second transceivers.

[0058] Furthermore, in step 508, the controller determines whether the voltage signal (Vo) representing the second DC voltage is less than the second threshold (VoMin). If the voltage signal (Vo) representing the second DC voltage is less than the second threshold (VoMin), the controller sends a second control signal to the switch to deactivate or open the switch, as shown in step 510. As a result, the second conversion unit is coupled to a contactless power transmission unit to receive power and supply it to an electrical load.

[0059] In step 512, the control unit receives a voltage signal (Vo) and a first control signal. The control unit receives the voltage signal (Vo) from the sensor via the first transceiver and the second transceiver. The control unit receives the first control signal from the controller via the first transceiver and the second transceiver.

[0060] Next, in step 514, the control unit deactivates the first converter unit when it receives the first control signal from the controller. The first converter unit is deactivated to prevent the supply of input power to the second converter unit. Furthermore, in step 516, the control unit transmits a reset signal to the controller via the first and second transceivers after a predetermined time. In response to receiving the reset signal, the controller generates a second control signal. Furthermore, the controller sends the second control signal to the switch to deactivate or open the switch. As a result, in step 508, the second converter unit is coupled to the contactless power transmission unit to receive power and supply it to the electrical load.

[0061] Simultaneously, in step 518, the controller transmits a second control signal to the control unit via the first and second transceivers. Furthermore, the sensor transmits a voltage signal (Vo) to the control unit via the first and second transceivers. Subsequently, in step 520, the control unit determines whether the voltage signal (Vo) representing the second DC voltage is less than or equal to a first threshold (VoMax). If the second DC voltage is less than or equal to the first threshold (VoMax), the control unit transmits a gate signal to activate the first converter unit. As a result, the input power is supplied to the second converter unit via the contactless power transmission unit. Furthermore, the electrical load receives power with the second DC voltage from the second converter unit. As a result, one or more components in the wireless power transmission unit are protected from the increase in the second DC voltage across the load.

[0062] Referring to Figure 6, a flowchart illustrating a method for adjusting the output voltage of a wireless power transmission system according to an embodiment of the present invention is shown. In step 602, a first DC voltage of the input power is converted to a first AC voltage. Specifically, a first conversion unit is coupled to a power supply to receive input power having the first DC voltage. Furthermore, the first conversion unit operates at a determined switching frequency to convert the first DC voltage of the input power to the first AC voltage.

[0063] Next, in step 604, the method includes the steps of receiving and transmitting input power having a first AC voltage. In particular, a contactless power transmission unit is electrically coupled to a first converter unit to receive input power having a first AC voltage. Furthermore, the contactless power transmission unit transmits input power having a first AC voltage to a second converter unit.

[0064] Furthermore, in step 606, the first AC voltage of the input power is converted to a second DC voltage. The second conversion unit is electrically coupled to a contactless power transmission unit to receive the input power having the first AC voltage. Furthermore, the second conversion unit converts the first AC voltage of the input power to a second DC voltage. In step 608, the input power having the second DC voltage is transmitted from the second conversion unit to an electrical load. In one embodiment, the electrical load may be one or more batteries that are charged by the input power having the second DC voltage received from the second conversion unit.

[0065] Furthermore, in step 610, the second DC voltage across the electrical load is adjusted if the second DC voltage across the electrical load is greater than a voltage reference value (Voref). A switching unit is electrically coupled to a second conversion unit and configured to adjust the second DC voltage across the electrical load. In particular, a sensor coupled to the output terminal of the second conversion unit is used to determine the second DC voltage across the electrical load. Furthermore, a controller coupled to the sensor is used to generate a control signal with the determined duty cycle based on the second DC voltage. More specifically, the controller compares the second DC voltage to a voltage reference value (Voref). If the second DC voltage is greater than the voltage reference value (Voref), the controller determines or selects a duty cycle corresponding to the second DC voltage. Furthermore, the controller generates a control signal with the selected or determined duty cycle. Subsequently, the controller supplies a control signal to the switch with a determined duty cycle to regulate the second DC voltage across the electrical load and protect the second converter from overvoltage damage.

[0066] According to the exemplary embodiments discussed herein, exemplary systems and methods facilitate the protection of one or more components in a wireless power transmission system when the load is disconnected. Furthermore, exemplary systems and methods facilitate the control or regulation of the output voltage when the load is disconnected. As a result, one or more components in the system are protected without decoupling the components in the system from each other.

[0067] While only certain features of this disclosure have been illustrated and described herein, many modifications and changes will be conceivable to those skilled in the art. Therefore, it should be understood that the appended claims are not intended to encompass all such modifications and changes as being within the true spirit of this disclosure. [Explanation of Symbols]

[0068] 100 Wireless Power Transmission Systems 102 Power supply 104 First conversion unit (inverter) 106 Control Unit 108 Contactless Power Transmission Unit 110 Second conversion unit (rectifier) 112 First DC voltage 114 First AC voltage 116 coils 118 Second DC voltage 120 sensors 122 First Transmitter / Receiver 124 Second Transmitter 126 Return Loop 128 Voltage signal (Vo) 130 Switching Units 132 Electrical load 200 Wireless Power Transmission Systems 202 Power supply 204 First conversion unit, first power conversion unit 206 Control Unit 208 Contactless Power Transmission Unit 210 Second conversion unit 212 Switching Unit 214 First Transmitter / Receiver 216 Second Transmitter 218 First DC voltage 220 switches 222 diodes 224 First AC voltage 226 gate signal 228 Primary coil 230 Secondary coil 232 Electrical load 234 Magnetic field focusing coil 236 Compensation coil 238 Second DC voltage (output voltage) 240 Diodes, MOSFETs, or IGBTs 242 Return Loop 244 sensors 246 Voltage signal (Vo) 248 Antenna 250 antennas 252 switches 254 Controllers 256 First comparator 258 Second comparator 260 Flip-Flop Unit 262 Reset signal 300 Wireless Power Transmission Systems 302 Controller 304 Control signal 400 ways 402, 404, 406, 408, 410 Step 500 ways Steps 502, 504, 506, 508, 510, 512, 514, 516, 518, 520, 522 600 ways 602, 604, 606, 608, 610 I

Claims

1. A device for receiving wireless power from a first conversion unit, A secondary coil configured to receive wireless power from a primary coil associated with the first conversion unit, wherein the wireless power has an alternating current (AC) voltage, A second conversion unit comprising a first plurality of circuit elements configured to convert the wireless power into an output direct current (DC) voltage, A first transceiver configured to communicate a signal representing the output DC voltage, wherein the signal is configured to cause the first conversion unit to adjust the AC voltage of the wireless power based on the signal representing the output DC voltage, A switching unit electrically coupled to the second conversion unit, comprising a plurality of second circuit elements configured to adjust the output DC voltage based on the output DC voltage and a voltage reference value, Equipped with, Device.

2. The apparatus according to claim 1, wherein the switching unit is configured to decouple the second conversion unit in order to protect one or more components of the apparatus.

3. The apparatus according to claim 2, wherein, in order to decouple the second conversion unit, the switching unit is configured to start after the first transceiver has communicated the signal representing the output DC voltage and decouple the second conversion unit during a period before the first conversion unit adjusts the wireless power.

4. The apparatus according to claim 1, wherein the first transceiver is further configured to receive a reset signal, the reset signal being for reconnecting the second conversion unit to an electrical load.

5. The apparatus according to claim 1, wherein the output DC voltage includes the output DC voltage across the terminals of an electrical load coupled to the second conversion unit, and the switching unit comprises a sensor electrically coupled to the electrical load and configured to determine the output DC voltage, and a controller electrically coupled to the sensor and the switch of the switching unit and configured to determine the duty cycle of a control signal configured to control the switch based on the output DC voltage.

6. The apparatus according to claim 5, wherein the controller is configured to generate and supply to the switch the control signal having the duty cycle in order to adjust the wireless power supplied to the second conversion unit.

7. The apparatus according to claim 5, wherein the controller is configured to determine the duty cycle of the control signal using a lookup table having a plurality of duty cycle values, and each of the plurality of duty cycle values ​​corresponds to a different output DC voltage.

8. The apparatus according to claim 5, wherein the first transceiver is configured to transmit the signal to the second transceiver of the first conversion unit.

9. The apparatus according to claim 8, wherein the control unit of the first conversion unit is communicatively coupled to the second transceiver, and the control unit comprises a digital circuit configured to adjust the switching frequency of the first conversion unit based on the signal representing the output DC voltage across the electrical load.

10. The apparatus according to claim 9, wherein the control unit is configured to adjust the switching frequency of the first conversion unit in order to adjust the output DC voltage.

11. The apparatus according to claim 10, wherein the control unit is configured to adjust the output DC voltage after the controller has adjusted the output DC voltage.

12. The apparatus according to claim 5, wherein the electrical load includes one or more batteries of a vehicle.

13. The apparatus according to claim 1, wherein the first conversion unit is electrically coupled to a power supply that provides a first DC voltage, and the first conversion unit is configured to convert the first DC voltage to the AC voltage.

14. The apparatus according to claim 1, wherein the switching unit configured to adjust the output DC voltage based on the output DC voltage and the voltage reference value includes a switching unit configured to adjust the output DC voltage when the output DC voltage is greater than the voltage reference value.

15. A method for receiving wireless power from a first conversion unit, Receiving wireless power having a first alternating current (AC) voltage from a primary coil associated with the first conversion unit via a secondary coil, The second conversion unit converts the wireless power into an output DC voltage, The first transceiver communicates a signal representing the output DC voltage, wherein the signal is configured to cause the first conversion unit to adjust the first AC voltage of the wireless power based on the signal representing the output DC voltage. The switching unit adjusts the output DC voltage based on the output DC voltage and a voltage reference value, including, method.

16. The method according to claim 15, further comprising decoupling the second conversion unit to protect one or more components of the second conversion unit.

17. The method according to claim 15, further comprising the first transceiver receiving a reset signal from a second transceiver of the first conversion unit, the reset signal being for reconnecting the second conversion unit to an electrical load.

18. The method according to claim 15, wherein the output DC voltage includes the output DC voltage across an electrical load, and adjusting the output DC voltage includes determining the output DC voltage by a sensor and determining the duty cycle of a control signal configured to control the switches of the switching unit based on the output DC voltage by a controller.

19. The method according to claim 18, wherein the control unit of the first conversion unit is configured to adjust the switching frequency of the first conversion unit based on the signal in order to adjust the output DC voltage.

20. The method according to claim 19, wherein the switching frequency of the first conversion unit is adjusted after the control signal is supplied to the switch.

Images