TWI757724B - Wireless power transmitter and power supply having the same - Google Patents

Abstract

The present invention reveals a power supply, including a wireless power transmitter and a wireless power receiver inductively coupled thereof. The wireless power receiver is provided for connecting with a load for power transmission. The wireless power transmitter has a controller. The controller detects the operation voltage and the operation current of a transmitter of the wireless power transmitter, tuning the frequency of the operation voltage according the phase difference between the operation voltage and the operation current. Therefore, the frequency of the operation voltage can be tuned close to the resonance frequency of the load, minimizing power transmission loss between the wireless power transmitter and the load, and increasing the allowable distance between the wireless power transmitter and the wireless power receiver.

Description

Wireless power transmitter and power supply system

The present invention provides a power supply system, which can transmit power by wireless induction, and then supply and drive the power load device.

Transmission of power by wireless induction can carry out ultra-distance power transmission in space. There is no need for physical circuit contact connection between the power supply side and the power receiving side, and it has better product design conditions and use effects. For related technologies, please refer to TWI660554, Description of patents such as TWI657635 and TWI655838.

In the aforementioned patents, in order to communicate and coordinate the working parameters between the power supply side and the power receiving side, such as the power supply voltage and power supply frequency of the power supply side, there are communication means between the power supply side and the power receiving side. Load detection circuit, connect the load detection circuit and output signals to the control circuit, and then further control the power supply side and the power receiving side; for example, the patent No. TWI660554 uses wireless communication to communicate between the power supply side and the power receiving side to Achieve status, parameter exchange and other purposes.

The aforementioned patent connects the power supply side and the power receiving side for communication. Although it can effectively achieve the purpose of parameter exchange, improve the power supply efficiency or other purposes, however, if the communication is performed through a physical circuit connection, it will lose the need to connect when using wireless induction to transmit power. The advantages of the physical circuit, and if the communication is performed by wireless communication, it is necessary to use a wireless communication device to run the communication protocol, resulting in an increase in equipment cost and a decrease in transmission speed or efficiency.

In view of this, one of the purposes of this creation is to provide a power supply technology that can rely solely on the detection and control of the power supply side, avoid the limitation of communication between the power supply side and the power receiving side, and provide the effect of stable power supply.

In order to achieve the above purpose, the present invention provides a wireless power transmitter for transmitting power to a wireless power receiver, the wireless power receiver has a receiver resonance frequency, and the wireless power transmitter includes a transmitter, a frequency converter and controller. A transmitter is configured to transmit power to the wireless power receiver, the transmitter having a transmitter resonant frequency. The frequency converter is connected to the transmitter and can be driven by electricity to output a working voltage to the transmitter. The working voltage has an oscillating frequency. When the working voltage is applied to the transmitter, a working current is generated. The controller is connected to the frequency converter, and the controller controls and adjusts the oscillation frequency according to the phase of the working voltage and the phase of the working current.

In some cases, the transmitter resonant frequency is the same as the receiver resonant frequency.

In the above-mentioned wireless power transmitter, the frequency converter is, for example, a half-bridge inverter.

In some cases, the controller adjusts the oscillation frequency to minimize the phase difference between the working voltage and the working current or approach a predetermined value, preferably, make the phase difference between the working voltage and the working current zero.

In some cases, the wireless power transmitter further includes a DC-DC converter, the DC-DC converter is connected to the frequency converter and can be driven by power to output a driving voltage to the frequency converter, and the controller is connected to the frequency converter. The DC-DC converter adjusts the driving voltage.

The present invention also provides a power supply system for supplying power to a power load device, the power load device has a resonance frequency, the power supply system includes the above-mentioned wireless power transmitter and a wireless power receiver, the receiver resonance frequency Same as the resonant frequency, the wireless power receiver can receive power from the wireless power transmitter and deliver it to the power load device.

In the above power supply system, the capacitance value of the transmitter is C1, the inductance value of the transmitter is L1, the capacitance value of the wireless power receiver is C2, the inductance value of the wireless power receiver is L2, and the inductance value of the wireless power receiver is L2. The resonant frequency of the electrical load device is fr, then:

Using the above device, the power supply system can use a wireless power transmitter and a wireless power receiver that are matched. Preferably, the resonant frequency of the transmitter is the same as the resonant frequency of the receiver. Induce voltage and current resonance between the wireless power transmitter and the wireless power receiver, increase the allowable distance between the wireless power transmitter and the wireless power receiver, and cause resonance in the wireless power transmitter, wireless power receiver or power load device When the frequency or resonant frequency changes, the phase change of voltage and current can be measured by the controller, and the oscillation frequency can be adjusted in time. There is no need for additional communication between the wireless power transmitter and the wireless power receiver to maintain resonance and obtain stability. and efficient power supply.

Please refer to FIG. 1 and FIG. 2. The present invention provides a power supply system, which is suitable for supplying power to an electrical load device, wherein the electrical load device has a resonant frequency. The present invention provides a power supply system including a wireless power transmitter 1 and a wireless power receiver. device 2.

The wireless power transmitter 1 includes a rectifier 11 , a DC-DC converter 12 , a frequency converter 13 , a transmitter 14 and a controller 15 .

The rectifier 11 is, for example, a bridge rectifier, which can accept an external AC power input and output a DC power V1.

The DC-DC converter 12 is, for example, a buck-boost converter, which is connected to the rectifier 11 and can be driven by the rectifier 11 by receiving electric power. In other possible embodiments of the present invention, a half-bridge type, full-bridge type, flyback type or other types of DC-DC voltage converters can also be used instead.

The frequency converter 13 is, for example, an inverter, which is connected to the DC-DC converter 12, can be driven by the driving voltage V2 output by the DC-DC converter 12, and outputs a working voltage V3 with periodic oscillation characteristics, and the working voltage V3 has Oscillation frequency, specifically, the frequency converter 13 is a half-bridge inverter, which outputs a working voltage V3 whose oscillation waveform is a square wave by means of a switching circuit. However, if a full-bridge inverter or other types of inverters are used instead, Neither is impossible.

The transmitter 14 is connected to the frequency converter 13, can be driven by the working voltage V3 and generate a working current I2, and is electromagnetically coupled with the wireless power receiver 2 to transmit power to the wireless power receiver 2, specifically, the transmitter 14 Including a transmitting coil 141 and a first capacitor 142, the transmitting coil 141 and the first capacitor 142 are connected in series, so that the transmitter 14 has a capacitance value C1 and an inductance value L1, wherein the inductance value L1 can be approximated by the inductance value of the transmitting coil 141 Therefore, the capacitance value C1 can be approximated by the capacitance value of the first capacitor 142, and the transmitter 14 has a transmitter resonance frequency fc1, which can be obtained by the following formula.

The controller 15 is, for example, a system-on-chip, connected to the DC-DC converter 12, the frequency converter 13 and the transmitter 14, and can be programmed to detect and monitor the validity of the operating voltage V3 and the operating current I2 output to the transmitter 14 value and phase, and control and adjust the DC-DC converter 12 and the frequency converter 13 according to the working voltage V3 and the working current I2, so as to adjust the phase of the working voltage V3 and the working current I2, and can adjust the working voltage V3 and the working current I2 The control is in the target range, and the target range is, for example, the target range preset or written into the controller 15, or/or simultaneously the target range input to the controller through the target command. Specifically, for the working voltage V3 and the working current The effective value of I2, when the working voltage V3 is too high or too low, the controller 15 controls the DC-DC converter 12 to step down or boost the voltage to adjust the driving voltage V2, thereby maintaining the stability of the working voltage V3, or reducing the working voltage V3 The control is within the target range. On the other hand, when the working current I2 is too high or too low, the controller 15 can also control the DC-DC converter 12 to step down or boost the voltage to adjust the driving voltage V2, and indirectly use the working voltage V3 to control The working current I2 controls the working current I2 within the target range; for the phase of the working voltage V3 and the working current I2, when the phase difference between the working voltage V3 and the working current I2 is zero, or the phase difference is preset and stored in the controller When the predetermined value in 15 represents that the oscillation frequency of the operating voltage V3 is synchronized with the resonant frequency of the power load device or conforms to a certain desired specific relationship, the controller 15 maintains the oscillation frequency generated by the frequency converter 13 at the operating voltage V3, when When the phase difference between the working voltage V3 and the working current I2 is not zero, or the phase difference deviates from a predetermined value, it means that the oscillation frequency of the working voltage V3 deviates from the resonant frequency of the power load device or a certain target value, and the controller 15 controls the frequency conversion. The controller 13 changes the oscillation frequency of the working voltage V3 until the phase difference between the working voltage V3 and the working current I2 is minimized or approaches zero or approaches a predetermined value.

Regarding the above-mentioned relationship between the phase difference between the working voltage V3 and the working current V2, the oscillation frequency of the working voltage and the resonant frequency of the power load device, the working voltage V3, the working current I2, and the voltage Vp and current Ip of the power load device can be measured and calculated. obtained after parsing. In a known experimental environment, the oscillation frequency of the working voltage can be preset to be equal to the resonant frequency of the power load device, and the waveforms of the working voltage V3, the working current V2, and the voltage Vp and current Ip of the power load device can be detected and drawn. As shown in FIG. 3 , the phases of the working voltage and the working current are nearly synchronized, the phase difference is close to zero, and the phases of the voltage and current of the power load device are also close to being synchronized. Please refer to Figure 4, when adjusting the oscillation frequency to reduce the operating voltage, or referring to Figure 5, after adjusting and increasing the oscillation frequency of the operating voltage, there is a phase difference between the operating voltage and the operating current and between the voltage and current of the power load device ψ, it can be judged that when the phases of the working voltage and the working current are close to synchronization, the oscillation frequency of the working voltage is also close to the resonance frequency of the electric load device.

It is worth mentioning that the electrical load device may have multiple resonant frequencies, and the controller can be controlled or switched by itself to control the oscillating frequency of the operating voltage to adjust and switch between several resonant frequencies. For example, the electrical load device can It has several resonant frequencies such as 25kHz, 50kHz, 75kHz, etc. The controller can control the frequency converter to output a working voltage with an oscillating frequency of 25kHz based on one of the resonance frequencies, such as 25kHz, and according to the phase difference between the working voltage and the working current, Adjust the oscillation frequency around 25kHz. In case of user switching or other preset events, the controller can switch to another resonance frequency, such as controlling the frequency converter based on 50kHz, which can be driven by several operating voltages with different oscillation frequencies electrical load device.

其中，無線電力接收器2與發射器14能經組態而使接收器共振頻率fc2與發射器共振頻率fc1相同，以提高無線電力接收器2與發射器14之間電磁耦合、傳輸電力的效率。The wireless power receiver 2 is similar in structure to the transmitter 14 , and is electromagnetically coupled with the transmitter coil 141 so as to receive power from the transmitter 14 . Specifically, the wireless power receiver 2 includes a receiver coil 21 and a second capacitor 22 , the receiving coil 21 is electromagnetically coupled with the transmitting coil 141, and the receiving coil 21 is connected in series with the second capacitor 22, so that the wireless power receiver 2 has a capacitance value C2 and an inductance value L2, wherein the inductance value L2 can be determined by the inductance value of the receiving coil 21. The capacitance value C2 can be approximated by the capacitance value of the second capacitor 22, and the wireless power receiver 2 has a receiver resonance frequency fc2, which can be obtained by the following formula.

The wireless power receiver 2 and the transmitter 14 can be configured so that the receiver resonance frequency fc2 is the same as the transmitter resonance frequency fc1, so as to improve the electromagnetic coupling and the power transmission efficiency between the wireless power receiver 2 and the transmitter 14 .

The power load device 31 is connected to the wireless power receiver 2, and the power load device 31 has a resonant frequency, and has a maximum power when subjected to the action of voltage and current oscillating at the resonant frequency, preferably, the resonant frequency and the receiver resonant frequency fc2 and transmit The resonant frequency fc1 of the device is the same, and the following formula is satisfied.

Using the above device, the user can supply a general AC connection to the wireless power transmitter, the rectifier converts the AC to DC, the DC-to-DC converter converts the DC to the DC with the required voltage, and the frequency converter converts the DC To supply the transmitter with the operating voltage with the required oscillation frequency, the transmitter and the wireless power receiver are electromagnetically coupled to transmit power, and then the power is supplied to the power load device to achieve power supply.

In the above power transmission path, the transmitter and the wireless power receiver transmit power by electromagnetic coupling, and the resonant frequency of the transmitter and the wireless power receiver is the same, which can increase the allowable distance between the transmitter coil and the receiver coil, Reduce the mechanism restriction on the coil setting position and improve the freedom of mechanism design.

Secondly, in the process of the above power transmission, the controller is further used to detect the phase of the working voltage and the working current of the transmitter, and adjust the oscillation frequency of the output working voltage of the frequency converter according to the phase difference, so as to make the difference between the working voltage and the working current as far as possible. The phase difference is minimized, so that the oscillating frequency of the working voltage can track the resonant frequency of the electrical load device, and the electrical load device can be driven with the working voltage that conforms to the resonant frequency, thereby obtaining better power transmission and use efficiency.

For the above-mentioned frequency tracking, the controller only detects the working voltage and current in the wireless power transmitter, and does not need to detect the wireless power receiver or the power load device, and does not need to derive additional signals from the wireless power receiver or the power load device, There is also no need to set up an additional communication device between the wireless power transmitter and the wireless power receiver, and extremely simplified mechanism and circuit design requirements can be maintained.

In the above-mentioned embodiment, the wireless power transmitter has a rectifier and a DC-to-DC converter, so that the user can input AC power with a wide range of voltages as the power source. The wireless power transmitter can also omit both or either of the rectifier and the DC-to-DC converter when the voltage is alternating current or the direct current of a specific voltage.

To sum up, the power supply system of the present invention is suitable for supplying power to the power load device, and can transmit power in a resonance manner, and it is possible to perform frequency tracking on the resonant frequency of the power load device without an additional communication device. Obtaining good power transmission and utilization efficiency under extremely simplified institutional constraints is what the relevant power technology industry expects. However, the above embodiment is only to illustrate and describe the technical content of this creation, and the patent scope of this patent should be described later. The range shall prevail.

V1: DC V2: drive voltage V3: working voltage Vp: The voltage of the electrical load device I1: drive current I2: working current Ip: Current of electrical load device ψ: phase difference 1: Wireless Power Transmitter 11: Rectifier 12: DC to DC Converter 13: Frequency Converter 14: Launcher 141: transmitter coil 142: First capacitor 15: Controller 2: Wireless Power Receiver 21: Receive coil 22: Second capacitor 31: Electrical load device

FIG. 1 is a schematic diagram of a power supply system created. Figure 2 is a circuit diagram of the power supply system of the creation. FIG. 3 to FIG. 5 are the actual measured waveform diagrams of the working voltage, the working current, and the voltage and current of the power load device in the creative power supply system.

V1: DC

V2: drive voltage

V3: working voltage

Vp: The voltage of the electrical load device

I1: drive current

I2: working current

Ip: Current of electrical load device

11: Rectifier

12: DC to DC Converter

13: Frequency Converter

14: Launcher

141: transmitter coil

142: First capacitor

15: Controller

2: Wireless Power Receiver

21: Receive coil

22: Second capacitor

31: Electrical load device

Claims (9)

A wireless power transmitter for transmitting power to a wireless power receiver, the wireless power receiver having a receiver resonance frequency, the wireless power transmitter comprising: a transmitter configured to transmit power to the wireless power receiver For power transmission, the transmitter has a transmitter resonance frequency; a frequency converter is connected to the transmitter and can be driven by power to output a working voltage to the transmitter, the working voltage has an oscillating frequency, and the working voltage is applied to the transmitter A working current is generated when the transmitter; a controller is connected to the frequency converter, the controller controls and adjusts the oscillation frequency according to the phase of the working voltage and the phase of the working current; wherein the capacitance value of the transmitter is C ₁ , the inductance value of the transmitter is L ₁ , the capacitance value of the wireless power receiver is C ₂ , the inductance value of the wireless power receiver is L ₂ , then:

The wireless power transmitter of claim 1, wherein the controller detects a phase difference between the operating voltage and the operating current, and if the phase difference is a predetermined value, maintains the oscillation frequency, and if the phase difference is not the If the predetermined value is set, the oscillation frequency is changed to make the phase difference approach the predetermined value. The wireless power transmitter of claim 1, wherein the controller detects a phase difference between the operating voltage and the operating current, and if the phase difference is zero, maintains the oscillation frequency If the phase difference is not zero, change the oscillation frequency to minimize the phase difference. The wireless power transmitter of claim 1, wherein the frequency converter is a half-bridge inverter. The wireless power transmitter according to any one of claims 1 to 4, further comprising a DC-DC converter connected to the frequency converter and capable of being driven by electricity to the frequency converter A driving voltage is output, and the controller is connected to the DC-DC converter to adjust the driving voltage. An electric power supply system for supplying electric power to an electric load device having a resonance frequency, the electric power supply system comprising: the wireless power transmitter according to any one of claim 1 to 4; In the wireless power receiver, the receiver resonance frequency is the same as the resonance frequency, and the wireless power receiver can receive power from the wireless power transmitter and transmit it to the power load device. The power supply system of claim 6, wherein the resonant frequency of the power load device is _fr , then:

A power supply system for supplying power to a power load device, the power load device having a resonance frequency, the power supply system comprising: the wireless power transmitter as claimed in claim 5; In the wireless power receiver, the receiver resonance frequency is the same as the resonance frequency, and the wireless power receiver can receive power from the wireless power transmitter and transmit it to the power load device. The power supply system of claim 8, wherein the resonant frequency of the power load device is _fr , then:

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