KR102195566B1 - Wireless power transfer system and driving method thereof - Google Patents

Abstract

The wireless power delivery system according to the embodiment transfers power from the primary side to the secondary side, and includes a secondary coil positioned on the secondary side, a capacitor and a control switch electrically connected in series between both ends of the secondary coil, and the And a regulation controller for controlling a switching operation of the control switch according to a result of comparing a control signal synchronized with a frequency of the primary side with a feedback signal corresponding to an output of the wireless power transfer system.

Description

Wireless power transmission system and its driving method TECHNICAL FIELD [WIRELESS POWER TRANSFER SYSTEM AND DRIVING METHOD THEREOF]

The embodiment relates to a wireless power transmission system and a driving method thereof.

The wireless power transmission system uses an induction coil to generate an AC electromagnetic field on the primary side, and the second induction coil on the secondary side receives power from the AC magnetic field generated on the primary side.

It may include a primary-side regulator (pre-regulator) or a secondary-side regulator (post-regulator, post-regulator) to control the output of the wireless power delivery system.

For example, in a pre-regulator type wireless power delivery system, information on an output voltage must be fed back through RF communication. Therefore, more RF communication circuits are needed along with the regulator.

In the poster-regulator type wireless power transfer system, an active load is required to match the impedance of the primary side and the impedance of the secondary side. Therefore, more active loads are required along with the regulator.

As described above, the conventional wireless power transfer system requires an RF communication circuit or an active load according to the type of the regulator together with the regulator. Increasing the size and power consumption according to the addition of the configuration may be a problem.

It is intended to provide a wireless power delivery system and a driving method thereof that can minimize additional configuration and improve power consumption.

The wireless power transfer system according to the embodiment transfers power from a primary side to a secondary side. The always-on wireless power transfer system includes a secondary coil positioned on the secondary side, a capacitor and a control switch electrically connected in series between both ends of the secondary coil, a control signal synchronized with the frequency of the primary side and the wireless power transmission. And a regulation controller for controlling a switching operation of the control switch according to a result of comparing a feedback signal corresponding to an output of the system.

The regulation controller may generate a control signal synchronized with a frequency of the primary side by rectifying a voltage that senses a current flowing through the secondary side.

The impedance of the secondary side may change according to the switching operation of the control switch.

The regulation controller is a current sensor that senses a current flowing to the secondary side and generates a sense voltage, a rectifier that generates the control signal by rectifying the sense voltage, a comparator that compares the control signal with the feedback signal, and the comparator And a gate driver generating a gate voltage according to the output of.

The wireless power transfer system is an error amplifier that outputs a result of comparing the output voltage and a predetermined reference voltage, and an error voltage as the feedback signal by being connected between an output terminal and an inverting terminal of the error amplifier to compensate for the output of the error amplifier. It further includes a compensator for generating.

The wireless power transfer system further includes a first resonant capacitor including one electrode connected to one end of the secondary coil, and the capacitor and the control switch include the other electrode of the first resonant capacitor and the secondary side. There may be a series connection between the other ends of the coil.

A method of driving a wireless power transfer system for transferring power from a primary side to a secondary side according to an embodiment includes generating a control signal using a current flowing through the secondary side, and a feedback signal corresponding to an output of the wireless power transfer system And controlling the impedance of the secondary side according to a result of comparing the control signal and the feedback signal.

The wireless power transfer system may include a capacitor and a control switch electrically connected in series between both ends of the secondary coil. The controlling the impedance of the secondary side includes controlling a switching operation of the control switch according to a result of comparing the control signal and the feedback signal.

Generating the control signal includes generating a sensing voltage by sensing a current flowing through the secondary side, and generating the control signal by rectifying the sensing voltage.

Generating the feedback signal includes compensating a result of comparing a voltage corresponding to the output voltage with a predetermined reference voltage to generate an error voltage as the feedback signal.

It provides a wireless power delivery system and a driving method thereof that can minimize additional configuration and improve power consumption.

1 is a diagram illustrating a wireless power delivery system according to an embodiment.
2 is a waveform diagram showing a control signal, an error voltage, and a gate control signal.
3 and 4 are waveform diagrams for explaining a change in an error voltage and a gate control signal according to an increase or decrease in a load.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those of ordinary skill in the art can easily implement the embodiments of the present invention. However, the present invention may be implemented in various different forms and is not limited to the embodiments described herein. In the drawings, parts irrelevant to the description are omitted in order to clearly describe the present invention, and similar reference numerals are assigned to similar parts throughout the specification.

Throughout the specification, when a part is said to be "connected" to another part, this includes not only "directly connected" but also "electrically connected" with another element interposed therebetween. . In addition, when a part "includes" a certain component, it means that other components may be further included rather than excluding other components unless specifically stated to the contrary.

1 is a diagram illustrating a wireless power delivery system according to an embodiment.

As shown in FIG. 1, the wireless power transfer system 1 includes a bridge-diode 10, a full-bridge inverter 20, a resonator 30, a rectifier circuit 40, and an error voltage generator. 50, and a regulation controller 60.

Bridge diode 10 full-wave rectifies the AC input (Vac). The AC input (Vac) passing through the bridge diode 10 is smoothed by the capacitor (Cin) to generate the input voltage (Vin). The input voltage Vin is supplied to the full-bridge inverter 20.

In FIG. 1, the wireless power transfer system 1 is implemented as a full-bridge inverter, but the invention is not limited thereto, and may be implemented as, for example, a half-bridge inverter.

The full-bridge inverter 20 is an example of a means for converting the input voltage Vin into a square wave. The full-bridge inverter 20 includes four switches Q1-Q4, and the input voltage Vin is converted into a square wave according to the switching operation of the four switches Q1-Q4.

Each of the four gate voltages VG1-VG4 is input to the gates of each of the four switches Q1-Q4. The switches Q1-Q4 are turned on by the enable level (high level) of the gate voltages VG1-VG4, and the switches Q1-Q4 are turned on by the disable level (low level) of the gate voltages VG1-VG4. ) Is turned off. Node N1 and node N2 are output nodes of the full-bridge inverter 20.

The switch Q1 is connected between the input voltage Vin and the node N1, and the switch Q2 is connected between the input voltage Vin and the node N2. The switch Q3 is connected between the node N1 and the primary ground, and the switch Q4 is connected between the node N2 and the primary ground.

When the switch Q1 and the switch Q4 are turned on, and the switch Q2 and the switch Q3 are turned off, the square wave voltage VRI is the input voltage Vin. When the switch Q2 and the switch Q3 are turned on, and the switch Q1 and the switch Q4 are turned off, the square wave voltage VRI is a -Vin voltage that is the opposite polarity of the input voltage Vin.

The resonator 30 includes primary and secondary coils CO1 and CO2, a resonant capacitor C1, and a resonant capacitor C2. The resonator 30 resonates the primary square wave supplied from the full-bridge inverter 20 and transfers power to the secondary side.

The resonance capacitor C1 is connected between the primary coil CO1 and the node N1. The square wave voltage VRI may be converted into a sine wave due to the leakage inductance Llkp and the magnetizing inductance Lm of the primary coil CO1 and resonance between the resonant capacitor C1.

The secondary coil (CO2) and the resonant capacitor (C2) are connected to the secondary side, and the turns ratio between the number of turns of the primary coil (CO1) and the number of turns of the secondary coil (CO2) is n:1 (column of CO1). Bow: Number of turns of CO2). The voltage VRO between the node N3 and the node N4 may be generated as a sine wave due to resonance between the leakage inductance Llks of the secondary coil CO2 and the resonant capacitor C2.

A rectifier circuit 40 and a capacitor Co are connected to the secondary side, and a load connected to the wireless power transfer system 1 is indicated by a resistor Ro.

The rectifying circuit 40 is a full-wave rectifying circuit including four diodes D1-D4. The cathode of the diode D1 is connected to the output voltage Vo, and the anode of the diode D1 is connected to the node N3. The cathode of the diode D2 is connected to the output voltage Vo, and the anode of the diode D2 is connected to the node N4. The cathode of the diode D3 is connected to the node N3, and the anode of the diode D3 is connected to the secondary ground. The cathode of the diode D4 is connected to the node N4, and the anode of the diode D4 is connected to the secondary ground. These four diodes (D1-D4) can also be implemented with four switches.

The capacitor Co attenuates the ripple of the output voltage Vo. The capacitor Co may be charged by the current supplied through the rectifier circuit 20, or the current may be discharged from the capacitor Co to the load Ro.

The error voltage generator 50 includes a compensator 51 and an error amplifier 52.

The error amplifier 52 amplifies and outputs the difference between the output voltage Vo and a predetermined reference voltage Vref. The compensator 51 compensates the output of the error amplifier 52.

Specifically, the compensator 51 is connected between the inverting terminal (-) of the error amplifier 52 and the output terminal. The inverting terminal (-) of the error amplifier 52 is connected to the output voltage Vo or a voltage corresponding to the output voltage, and the non-inverting terminal (+) is connected to the reference voltage Vref. The compensator 51 generally compensates the output of the error amplifier 52 through a proportional integral (PI) control to generate an error voltage VEA. The error voltage VEA is an example of a feedback signal corresponding to the output of the wireless power transfer system, and the present invention is not limited thereto.

The regulation controller 60 senses the secondary current, generates a control signal (VCON) synchronous to the primary frequency, and compares the error voltage (VEA) with the control signal (VCON). Controls the switching operation of (Qs). The impedance of the secondary side changes according to the switching duty of the control switch Qs.

The primary side frequency may be determined according to the switching frequency of the full-bridge inverter 20. The regulation controller 60 generates a control signal VCON by rectifying the voltage VIs that senses the secondary current Is. Then, the control signal VCON is synchronized with the primary side frequency.

The regulation controller 60 includes a control switch Qs, a capacitor Cs, a rectifier 61, a comparator 62, a gate driver 63, and a current sensor 64.

The control switch Qs and the capacitor Cs are connected in series between the node N3 and the node N4. One electrode of the capacitor Cs is connected to the node N3, and the other electrode of the capacitor Cs is connected to the drain of the control switch Qs. The gate voltage Vgss is input to the gate of the control switch Qs, and the source of the control switch Qs is connected to the node N4. The connection relationship between the capacitor Cs and the control switch Qs may be different from the order shown in FIG. 1. For example, the connection order of the capacitor Cs and the control switch Qs may be changed.

The current sensor 64 senses the secondary current Is and generates a voltage VIs. The secondary-side current Is and the primary-side current Ip have the same frequency, and the primary-side current Ip is generated in synchronization with the switching frequency of the full-bridge inverter 20.

The rectifier 61 generates a control signal VCON by full-wave rectifying the voltage VIs.

The comparator 62 generates a gate control signal Vgs according to a result of comparing the control signal VCON and the error voltage VEA. The error voltage VEA is input to the inverting terminal (-) of the comparator 62, and the control signal VCON is input to the non-inverting terminal (+). The comparator 62 generates a gate control signal Vgs that enables the control switch Qs when the control signal VCON is equal to or higher than the error voltage VEA. In the opposite case, the comparator 620 generates a gate control signal Vgs that disables the control switch Qs.

In the embodiment, it will be described that the enable level of the gate control signal Vgs is a high level and the disable level is a low level. However, the invention is not limited thereto.

The gate driver 63 generates a gate voltage Vgss according to the gate control signal Vgs. For example, the gate driver 63 generates a high level gate voltage Vgss according to a high level gate control signal Vgs, and a low level gate voltage Vgs according to the low level gate control signal Vgs. Vgss).

2 is a waveform diagram illustrating a control signal, an error voltage, and a gate control signal according to an embodiment.

As illustrated in FIG. 2, the gate control signal Vgs rises to a high level at a point T1 when the rising control signal VCON reaches the error voltage VEA. Then, the control switch Qs is turned on so that a part of the secondary current Is flows to the capacitor Cs of the regulation controller 60. When the control signal VCON becomes smaller than the error voltage VEA at the time point T2, the gate control signal Vgs falls to the low level. Then, the control switch Qs is turned off and the secondary current Is is transferred to the load through the rectifier circuit 40.

3 and 4 are waveform diagrams for explaining a change in an error voltage and a gate control signal according to an increase or decrease in a load.

3 is a waveform diagram for a condition in which an output voltage Vo decreases due to an increase in load and an error voltage VEA increases.

As shown in FIG. 3, the error voltage VEA increases to the level of VEA1 compared to FIG. 2. Then, the control switch Qs is turned on during the period T11-T12 in which the gate control signal Vgs is enabled. In order to increase the amount of current delivered to the load as the load increases, it is necessary to decrease the current flowing to the regulation controller 60. To this end, the duty of the control switch Qs is reduced compared to FIG. 2.

4 is a waveform diagram for a condition in which the output voltage Vo increases due to a decrease in the load and the error voltage VEA decreases.

As shown in FIG. 4, the error voltage VEA falls to the VEA2 level compared to FIG. 2. Then, the control switch Qs is turned on during the period T21-T22 in which the gate control signal Vgs is enabled. It is necessary to increase the current flowing to the regulation controller 60 in order to reduce the amount of current delivered to the load as the load decreases. To this end, the duty of the control switch Qs is increased compared to FIG. 2.

In this way, the secondary impedance is controlled according to the switching operation of the control switch Qs, so that the current supplied to the load can be controlled. In addition, it is possible to regulate the output voltage only by the regulation controller 60 without a separate active load or RF communication circuit. Since the active load is not used, power consumption can be reduced, and since the active load and RF communication circuit are not included, the configuration can be simplified.

Although the embodiments of the present invention have been described in detail above, the scope of the present invention is not limited thereto, and various modifications and improvements by those skilled in the art using the basic concept of the present invention defined in the following claims are also provided. It belongs to the scope of rights.

1: wireless power delivery system
10: bridge diode
20; Full-bridge inverter
30: resonator
40: rectifier circuit
CO1: primary side coil
CO2: secondary coil

Claims (10)

In the wireless power transfer system for transferring power from the primary side to the secondary side,
A secondary side coil located on the secondary side,
A capacitor and a control switch electrically connected in series between both ends of the secondary coil,
Generates a control signal corresponding to the secondary current flowing through the secondary coil, and controls the switching operation of the control switch according to a result of comparing the control signal with a feedback signal corresponding to the output voltage of the wireless power transfer system A regulation controller;
An error amplifier outputting a result of comparing the output voltage of the wireless power transfer system with a predetermined reference voltage; And
And a compensator connected between the output terminal of the error amplifier and an inverting terminal to compensate for the output of the error amplifier to generate an error voltage as the feedback signal. The method of claim 1,
The regulation controller,
A wireless power delivery system for generating the control signal by rectifying a sensing voltage corresponding to the secondary current. The method of claim 1,
The wireless power delivery system in which the impedance of the secondary side changes according to the switching operation of the control switch. The method of claim 1,
Further comprising a current sensor for sensing the secondary current and generating a detection voltage corresponding to the sensed secondary current,
The regulation controller,
A rectifier configured to rectify the sense voltage to generate the control signal;
A comparator for comparing the control signal and the feedback signal, and
A wireless power transfer system comprising a gate driver generating a gate voltage of the control switch according to an output of the comparator. The method of claim 1,
Further comprising a first resonant capacitor including one electrode connected to one end of the secondary coil,
The capacitor and the control switch,
A wireless power transfer system connected in series between the other electrode of the first resonant capacitor and the other end of the secondary coil. In the driving method of a wireless power transfer system for transferring power from a primary side to a secondary side,
Generating a control signal using the current flowing through the secondary side;
Generating a feedback signal corresponding to an output voltage of the wireless power delivery system;
Comparing the feedback signal and the control signal; And
And controlling the impedance of the secondary side according to a result of comparing the control signal and the feedback signal,
The wireless power transfer system includes an error amplifier and a compensator connected between the output terminal of the error amplifier and an inverting terminal,
Generating the feedback signal,
Comparing the output voltage with a predetermined reference voltage by the error amplifier; And
Compensating the output of the error amplifier by the compensator to generate an error voltage as the feedback signal,
How to drive a wireless power delivery system. The method of claim 6,
The wireless power delivery system,
Further comprising a capacitor and a control switch electrically connected in series between both ends of the secondary coil located on the secondary side,
Controlling the impedance of the secondary side,
And controlling a switching operation of the control switch based on a result of comparing the control signal and the feedback signal. The method of claim 6,
Generating the control signal,
Generating a sensing voltage by sensing the current flowing through the secondary side, and
And generating the control signal by rectifying the sensed voltage. A primary coil through which a primary current flows from the primary side;
A secondary coil on the secondary side magnetically coupled to the primary coil;
A control switch connected to the secondary coil;
A first rectifier configured to generate a rectified voltage by rectifying a sensing voltage corresponding to a secondary current flowing through the secondary coil;
A second rectifier for generating an output voltage by rectifying the voltage across the secondary side;
An error amplifier outputting a result of comparing the output voltage and a predetermined reference voltage;
A compensator connected between the output terminal of the error amplifier and an inverting terminal to compensate for the output of the error amplifier to generate an error voltage as a feedback signal; And
And a regulation controller controlling a switching operation of the control switch according to a result of comparing the rectified voltage and the feedback signal. The method of claim 9,
The regulation controller,
A wireless power transfer system further comprising a capacitor connected in series to the control switch connected to both ends of the secondary coil.

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