CN-122003797-A - Wireless power transmission system and method

CN122003797ACN 122003797 ACN122003797 ACN 122003797ACN-122003797-A

Abstract

A wireless power transfer system includes a transmitter unit including a first transceiver coupled to a first induction coil and configured to drive the first induction coil, and a receiver unit including a second transceiver coupled to a second induction coil for inductive coupling with the first induction coil, wherein the receiver unit further includes an injection-locked oscillator coupled to the second transceiver for determining an oscillation frequency of the second transceiver, the injection-locked oscillator configured to be synchronized with a driving frequency of the transmitter unit.

Inventors

Paul D. Mickey Sen
Chris Papawasiliu
James. Gavis
Nuzio Puchi

Assignees

帝国大学创新有限公司

Dates

Publication Date: 20260508
Application Date: 20240726
Priority Date: 20230728

Claims (15)

1. A wireless power transfer system, the wireless power transfer system comprising: a transmitter unit comprising a first transceiver coupled to a first induction coil, and the first transceiver is configured to drive the first induction coil; and A receiver unit comprising a second transceiver coupled to a second induction coil, the second induction coil is used for performing inductive coupling with the first induction coil; Wherein the receiver unit further comprises an injection locked oscillator coupled to the second transceiver for defining an oscillation frequency of the second transceiver, the injection locked oscillator being configured to be synchronized with a driving frequency of the transmitter unit.
2. The wireless power transfer system of claim 1, wherein the transmitter unit further comprises an oscillator coupled to the first transceiver, the oscillator defining a stable oscillation frequency of the first transceiver.
3. The wireless power transfer system of claim 1 or 2, wherein the injection-locked oscillator has a low Q factor.
4. A wireless power transfer system according to any preceding claim, wherein the injection locked oscillator is a nonlinear oscillator.
5. The wireless power transfer system of any preceding claim, wherein at least one of the first transceiver and the second transceiver is an EF-class transceiver.
6. The wireless power transfer system of any preceding claim, wherein at least one of the first and second induction coils comprises an air core coil.
7. A wireless power transfer system according to any preceding claim, wherein the first transceiver and the second transceiver belong to the same class.
8. The wireless power transfer system of any preceding claim, wherein the receiver unit further comprises a delay line configured to maintain a phase offset of 90 ° relative to the transmitter unit.
9. A wireless power transfer system according to any preceding claim wherein the second transceiver is tuned to implement a load independent of the first transceiver.
10. A wireless power transfer system according to any preceding claim, wherein the injection-locked oscillator is a voltage-controlled injection-locked oscillator having a voltage-tunable natural oscillation frequency.
11. The wireless power transfer system of any preceding claim, wherein the receiver unit further comprises a temperature sensor and a control unit configured to determine the temperature at the receiver unit based on an output from the temperature sensor.
12. The wireless power transfer system of claim 11 when dependent on claim 10, wherein the control unit is configured to: determining a temperature change at the receiver unit based on an output from the temperature sensor; Determining a change in natural oscillation frequency of the injection locked oscillator with a change in temperature based on a lookup table; Determining a voltage change required to counteract the change based on the determined change in natural oscillation frequency; The voltage variation is applied to the injection locked oscillator.
13. A method of controlling a receiver unit for an inductive power transfer system, the receiver unit comprising a transceiver coupled to an inductive coil, and a voltage controlled injection locked oscillator coupled to the transceiver for defining an oscillation frequency of a second transceiver, the method comprising: determining a temperature change at the receiver unit; determining a change in natural oscillation frequency of the injection-locked oscillator with a change in temperature; determining the voltage change required to counteract said change, and The voltage variation is applied to the injection locked oscillator.
14. The wireless power transfer system of claim 11, wherein the control unit is configured to: causing the delay line to introduce a phase disturbance to an oscillating signal transmitted from the injection locked oscillator to the second transceiver; For each phase disturbance, determining an inductive power at the receiver unit based on an output of the second transceiver; determining a phase disturbance that maximizes the inductive power, and The delay line is controlled to maintain the induced power at the maximum of the phase disturbance.
15. A method of controlling a receiver unit for an inductive power transfer system, the receiver unit comprising a transceiver coupled to an inductive coil, a voltage controlled injection locked oscillator coupled to the transceiver for defining an oscillation frequency of the transceiver, and a delay line, the method comprising: causing a delay line to introduce a phase disturbance to an oscillating signal transmitted from an injection locked oscillator to the transceiver; for each phase disturbance, determining an inductive power at the receiver unit based on an output from the transceiver; Determining a phase disturbance that maximizes the inductive power; the delay line is controlled to maintain the induced power at the maximum of the phase disturbance.

Description

Wireless power transmission system and method This work was supported by the Committee of engineering and physical science and by the ERPSRC approval numbers EP/N509486/1, EP/R513052/1 and EP/R029504/1. Technical Field The present disclosure relates to wireless power transfer systems and corresponding methods thereof. Background For example, wireless Power Transfer (WPT), and in particular Inductive Power Transfer (IPT), is becoming increasingly popular as a common technique for powering and charging electronic devices. Currently, wireless power transfer is most commonly used for relatively low power applications. However, there is also a great interest in applying inductive wireless power transfer to higher power inductive power transfer (HP-IPT). Active-passive (active-passive) systems are commonly used for IPT. In an active-passive system, the receiver is a passive element that can only operate as a receiver. Thus, active-passive systems are only suitable for unidirectional power transmission. Another disadvantage of active-passive systems is that the reflection reactance in the system can cause the system to be detuned, making such systems difficult to tune for different operating conditions (e.g., different separation distances, different coil overlaps, different temperatures). For high power systems, the losses due to detuning will be more difficult to control. Active-active (active-active) systems are receiving increasing attention in the IPT field. In an active-active system, both the transmitter and the receiver are active devices and can be reconfigured to enable bi-directional power transfer. Active-active systems can solve the tuning problems faced by active-passive systems and may be more efficient than active-passive systems. However, active-active systems are difficult to implement. In particular in active-active systems, it is challenging to obtain a stable frequency and phase reference between the transmitter and the receiver, which in turn leads to poor synchronicity and thus lower power efficiency with respect to many active-passive systems. In some systems, a separate communication link may be used to facilitate synchronization. However, such a separate communication link may increase the complexity and cost of the system and may be difficult to extend to high frequency operation, such as megahertz level operation. Disclosure of Invention The present invention aims to solve the above-mentioned problems. In a first aspect, a wireless power transfer system is provided that includes a transmitter unit (first unit) including a first transceiver coupled to a first induction coil and configured to drive the first induction coil, and a receiver unit (second unit) including a second transceiver coupled to a second induction coil for inductive coupling with the first induction coil, wherein the receiver unit further includes an injection-locked oscillator coupled to the second transceiver for defining an oscillation frequency of the second transceiver, the injection-locked oscillator configured to be synchronized with a drive frequency of the transmitter unit (e.g., synchronized with a frequency at which the first coil is driven). For example, the injection locked oscillator may be provided for synchronizing the oscillation frequency of the second transceiver with the driving frequency of the transmitter unit. The injection locked oscillator may also alternatively be referred to as an injection locked oscillator, e.g., an oscillator configured to be injection locked with another frequency. Injection locked oscillators are a term of art in radio frequency communication systems. Herein, a transmitter unit is defined as a unit configured to inductively transmit energy in a wireless power transmission system. Equivalently, a receiver unit is defined as a supplemental unit in a wireless power transfer system configured to inductively couple with such a transmitter unit to receive and capture inductively transferred energy. As the reader will appreciate, since the transmitter unit of the first aspect comprises a transceiver, it may alternatively be configured as a receiver (e.g. by switching the first transceiver from a transmitting mode to a receiving mode). Similarly, since the receiver unit of the first aspect comprises the second transceiver, it may alternatively be configured as a transmitter (e.g. by switching the second transceiver to a transmit mode). That is, the transmitter unit of the first aspect may be a transmit/receive unit in which the first transceiver is switched to operate as a transmitter, and the receiver unit of the first aspect may also be a transmit/receive unit in which the second transceiver is switched to operate as a receiver. By using a transceiver-based receiver, bi-directional power transfer may be achieved (e.g., by switching the transmitter to operate as a receiver; and by switching the receiver to operate as a transmitter). In contrast, if a passive receiver (e.g., a r