KR102812101B1 - Method and apparatus for transfering wireless power based on series-series compesated inductive power transfer - Google Patents

Abstract

A wireless power transmission device based on S-S (Series-Series) compensation IPT (inductive power transfer) is disclosed. The device may include a full bridge-based inverter for wireless power transmission, a controller for setting a duty ratio and frequency of the inverter, a rectifier connected at one end to the inverter and an inductor-based S-S compensation network, and the other end of the S-S compensation network and rectifying the transmitted AC power into DC, and the controller may adjust the single-pole duty ratio based on the sensed output current when an output current output through the rectifier is sensed and an input current is sensed, and may adjust the driving frequency based on the sensed input current. Accordingly, the wireless power transmission device may operate efficiently.

Description

S-S Compensation IPT Based Wireless Power Transfer Method and Device {METHOD AND APPARATUS FOR TRANSFERING WIRELESS POWER BASED ON SERIES-SERIES COMPESATED INDUCTIVE POWER TRANSFER}

The present disclosure relates to a wireless power transmission method based on S-S compensation IPT and a device therefor.

Wireless power transfer (WPT) technology has the potential to replace existing plug-in power transmission due to its unique advantages such as safety, flexibility, and low maintenance costs, and WPT technology is attracting attention as it enters a promising commercial market.

Among WPT technologies, inductive power transfer (IPT) technology has been widely studied and is being applied in various battery charging applications including electric vehicles (EVs), unmanned aerial vehicles (UAVs), consumer electronics, and biomedical implants.

Compensation topologies can be applied in IPT systems, and these compensation topologies can be classified into four basic types: series-series (S-S), series-parallel (S-P), parallel-series (P-S), and parallel-parallel (P-P). In the case of the series-series (S-S) compensation topology, a load-independent constant current output is possible with a simple design by applying two compensation capacitors, and thus it is widely used.

Therefore, a wireless power transmission device based on a more efficient and improved S-S compensation IPT system is required.

Publication of Patent Publication No. 10-2015-0139067 (December 11, 2015)

An object of the present disclosure to solve the above-described problems is to provide a wireless power transmission and reception device that achieves zero-voltage switching (ZVS) and constant current based on a single-pole duty cycle modulation technique.

The problems to be solved by the present disclosure are not limited to the problems mentioned above, and other problems not mentioned will be clearly understood by those skilled in the art from the description below.

In order to solve the above-described problem, a wireless power transmission device based on S-S (Series-Series) compensation IPT (inductive power transfer) according to the present disclosure may include a full bridge-based inverter for wireless power transmission; a controller that sets a duty ratio and a frequency of the inverter; an inductor-based S-S compensation network connected at one end to the inverter; and a rectifier connected to the other end of the S-S compensation network and rectifying the transmitted AC power into DC.

The above controller can adjust the unipolar duty cycle based on the sensed output current when the output current output through the above rectifier is sensed and the input current is sensed, and can adjust the driving frequency based on the sensed input current.

The above controller can be configured to independently adjust the single-pole ratio and the driving frequency.

The controller may be configured to activate zero-voltage switching (ZVS) tracking and constant current tracking, and to stop the unipolar duty cycle and the frequency adjustment when the sensed output current exceeds a threshold output current or the sensed input current exceeds a threshold input current.

The above controller can be adjusted to increase the driving frequency by a predetermined amount when the sensed input current exceeds a first boundary current if zero-voltage switching (ZVS) tracking is activated, decrease the driving frequency by a predetermined amount when the sensed input current is lower than or equal to the first boundary current and exceeds a second boundary current, and maintain the driving frequency when the sensed input current is lower than or equal to the second boundary current.

The above controller may be configured to repeatedly adjust the driving frequency until the adjusted driving frequency exceeds a predetermined threshold.

The above controller may be configured to adjust the single-pole ratio by performing PI control using the output current and reference current when adjusting the single-pole ratio.

In addition, in a control method of a wireless power transmission device based on S-S (Series-Series) compensation IPT (inductive power transfer) according to the present disclosure, the wireless power transmission device may include a full bridge-based inverter for wireless power transmission, a controller for setting a duty ratio and frequency of the inverter, an inductor-based S-S compensation network having one end connected to the inverter and the other end connected to the S-S compensation network and a rectifier for rectifying the transmitted AC power into DC.

The above control method may include a step of sensing an output current output through the rectifier and sensing an input current; and a step of adjusting a unipolar duty cycle based on the sensed output current and adjusting a driving frequency based on the sensed input current.

The above adjusting step may include a step of independently adjusting the single-pole ratio and the driving frequency.

The above control method may further include a step of activating zero-voltage switching (ZVS) tracking and constant current tracking, and stopping the unipolar duty ratio and the frequency adjustment when the sensed output current exceeds a threshold output current or the sensed input current exceeds a threshold input current.

The above adjusting step may include an adjusting step of increasing the driving frequency by a predetermined amount when the sensed input current exceeds a first boundary current if zero-voltage switching (ZVS) tracking is activated, decreasing the driving frequency by a predetermined amount when the sensed input current is lower than or equal to the first boundary current and exceeds a second boundary current, and maintaining the driving frequency when the sensed input current is lower than or equal to the second boundary current.

The above adjusting step may include a step of repeatedly adjusting the driving frequency until the adjusted driving frequency exceeds a predetermined threshold value.

The above adjusting step may include a step of adjusting the single-pole ratio by performing PI control using the output current and reference current when adjusting the single-pole ratio.

In addition, other methods for implementing the present invention, other systems, and computer-readable recording media recording a computer program for executing the method may be further provided.

According to the present disclosure, zero voltage switching (ZVS) and constant current of a wireless power transmission device can be achieved by dynamically controlling the duty ratio and frequency under various coupling coefficients and loads, and the zero voltage switching (ZVS) and constant current can be stably and accurately tracked.

The effects of the present invention are not limited to the effects mentioned above, and other effects not mentioned will be clearly understood by those skilled in the art from the description below.

Figure 1 illustrates a wireless power transmission device according to the present disclosure.
Figure 2 is a drawing for explaining in detail the operating method of the wireless power transmission device.
FIG. 3 is a sequence diagram showing a schematic operation process of a wireless power transmission device according to the present disclosure.
FIG. 4 is a sequence diagram illustrating a method for adjusting the frequency of a wireless power transmission device according to the present disclosure.
FIG. 5 shows a schematic diagram of input current sensing according to the present disclosure.
Fig. 6 shows an equivalent circuit corresponding to the circuit of the wireless power transmission device illustrated in Fig. 1.
FIG. 7 is a diagram for explaining a process of adjusting a single-pole ratio through PI control according to the present disclosure.
Figure 8 illustrates MATLAB-based body plots according to the present disclosure.
Figures 9 to 11 show PSIM simulation results of single-pole ratio control under different transient conditions according to the present disclosure.
FIG. 12(a) and FIG. 12(b) show the adjusted driving frequency and duty ratio of the wireless power transmission device according to the present disclosure.
Figure 13 shows measured values of current and voltage corresponding to input and output when the output power according to the present disclosure is 200 W.
Figure 14 shows measured values of current and voltage corresponding to input and output when the output power according to the present disclosure is 500 W.

Throughout this disclosure, the same reference numerals refer to the same components. This disclosure does not describe all elements of the embodiments, and any content that is general in the technical field to which this disclosure belongs or that overlaps between the embodiments is omitted. The terms 'part, module, element, block' used in the specification can be implemented in software or hardware, and according to the embodiments, a plurality of 'parts, modules, elements, blocks' can be implemented as a single component, or a single 'part, module, element, block' can include a plurality of components.

Throughout the specification, when a part is said to be "connected" to another part, this includes not only a direct connection but also an indirect connection, and an indirect connection includes a connection via a wireless communications network.

Additionally, when a part is said to "include" a component, this does not mean that it excludes other components, but rather that it may include other components, unless otherwise specifically stated.

Throughout the specification, when it is said that an element is "on" another element, this includes not only cases where the element is in contact with the other element, but also cases where there is another element between the two elements.

The terms first, second, etc. are used to distinguish one component from another, and the components are not limited by the aforementioned terms.

Singular expressions include plural expressions unless the context clearly indicates otherwise.

The identification codes in each step are used for convenience of explanation and do not describe the order of each step. Each step may be performed in a different order than specified unless the context clearly indicates a specific order.

The operating principle and embodiments of the present disclosure are described below with reference to the attached drawings.

FIG. 1 illustrates a wireless power transmission device (100) according to the present disclosure.

The wireless power transmission device (100) can be implemented based on an inductive power transfer (IPT) system that transmits power in an inductive manner, and can achieve constant-current output and zero-voltage switching (ZVS) by dynamically controlling the duty ratio and frequency at various coupling coefficients and loads.

A wireless power transmission device (100) may include an inverter (120), a controller (180, 190), an S-S compensation network, and a rectifier (140).

The inverter (120) may be a full bridge-based inverter for wireless power transmission. The ratio and frequency can be set using four switches (S1 to S4), and direct current can be converted into alternating current.

The controller (180, 190) may include a controller (190) that determines the duty ratio and frequency of the inverter (120) and a PWM Generator (180, pulse width modulation) that sets the duty ratio and frequency according to the control of the controller (190). The controller (190) and the PWM Generator (180) are separate components, but for convenience of explanation, they will be described together.

The S-S compensation network (Series-Series compensated network) is a module for transmitting power based on an induced electromotive force based on an inductor (Lp, Ls) and one end is connected to an inverter (120). A capacitor (Cp) of a transmitter and a capacitor (Cs) of a receiver can be connected in series, and wireless power can be transmitted AC to AC from a transmitter to a receiver.

The rectifier (140) may include a rectifier that is connected to the other end of the S-S compensation network and rectifies the transmitted AC power into DC, and a single-phase bridge rectifier may be applied, but the embodiment is not limited thereto.

Figure 2 is a drawing for explaining in detail the operating method of the wireless power transmission device (100).

The controller (190) can calculate a frequency based on the sensed input current (I _{in_sen} ), and can adjust the unipolar duty cycle by performing PI (proportional integral) control based on the sensed output current (I _{b_sen} ) and reference current (l _{b_ref} ).

The controller (190) independently performs the first process (Pr1, 190) and the second process (Pr2, 190), so that the single-pole ratio and frequency can be adjusted independently.

When adjusting the single-pole ratio, the controller (190) can adjust the single-pole ratio by performing PI control on the output current (I _{b_sen} ) and reference current (l _{b_ref} ).

The controller (190) can control the driving frequency based on the sensed input current (I _{in_sen} ).

According to the circuit illustrated in Figure 2, the duty ratio and frequency can be dynamically controlled at various coupling coefficients and loads to achieve constant current and ZVS.

FIG. 3 is a sequence diagram showing a schematic operation process of a wireless power transmission device (100) according to the present disclosure, FIG. 4 is a sequence diagram showing a method for adjusting a frequency of a wireless power transmission device (100) according to the present disclosure, and FIG. 5 is a schematic diagram showing input current sensing according to the present disclosure. FIG. 6 shows an equivalent circuit corresponding to the circuit of the wireless power transmission device (100) shown in FIG. 1. FIG. 7 is a diagram for explaining a process of adjusting a single-pole duty ratio through PI control according to the present disclosure. FIG. 8 shows MATLAB-based body plots according to the present disclosure.

Referring to FIG. 3, the controller (190) can initialize each parameter (S310).

The controller (190) can set the driving frequency to 100 kHz, the single-pole duty ratio to 0.5, the input reference current to 10 A, the first boundary current to -0.5, the second boundary current to -1.5, the critical input current to 1 A, and the output critical current to 12 A, but the embodiment is not limited thereto.

The controller (190) can activate ZVS tracking and constant current tracking (S320).

The IPT system can be operated normally (S330) and the operation can be stopped when the sensed output current (I _{b_sen} ) exceeds the output threshold current or the sensed input current (l _{in_sen} ) exceeds the input threshold current (S340).

The controller (190) can perform power transfer for wireless charging until wireless charging is completed (S350) when the sensed output current (I _{b_sen} ) is less than or equal to the output threshold current and the sensed input current (I _{in_sen} ) is less than or equal to the input threshold current (S340).

Referring to FIG. 4, the controller (190) activates ZVS tracking (S410), senses input current (S420), secures time for frequency control using a counter (S430 to S450), increases the driving frequency (e.g., 200 Hz) (S460) if the input current is greater than the first boundary current (S455), decreases the driving frequency (S470) if it is less than the first boundary current but greater than the second boundary current (S465), and otherwise maintains the frequency.

Referring to FIG. 5, the sensing value of the input current can be measured as being less than the first boundary and more than the second boundary by operating the switch of the inverter (120).

Referring to Fig. 8, it can be confirmed that the control loop has stable phase and amplitude margins, and the magnitude and phase curves for various load conditions almost overlap within the low frequency range, so it can be confirmed that the stability margin shows little difference within the entire load range.

FIGS. 9 to 11 show PSIM simulation results of single-pole ratio control under different transient conditions according to the present disclosure, wherein FIG. 9 shows the case where various coupling coefficients (R _L = 5 ohm, I _{b_ref} = 10A) are applied, FIG. 10 shows the case where various load conditions (k = 0.252, I b_ref = 10A) are applied, and FIG. 11 shows the case where various reference current conditions are applied (k = 0.252, R _L = 5 ohm).

FIG. 12(a) and FIG. 12(b) show the adjusted driving frequency and duty ratio of the wireless power transmission device (100) according to the present disclosure.

FIG. 13 shows measured values of current and voltage corresponding to input and output when the output power according to the present disclosure is 200 W, and FIG. 14 shows measured values of current and voltage corresponding to input and output when the output power according to the present disclosure is 500 W.

It can be confirmed that ZVS and constant current are achieved in Figs. 13 and 14.

As described above, the controller (190) can adjust the unipolar duty cycle based on the sensed output current when the output current output through the rectifier is sensed and the input current is sensed, and can adjust the driving frequency based on the sensed input current.

The above controller can independently adjust the single-pole ratio and the driving frequency.

The above controller can activate zero-voltage switching (ZVS) tracking and constant current tracking, and stop the unipolar duty cycle and the frequency adjustment when the sensed output current exceeds a threshold output current or the sensed input current exceeds a threshold input current.

The above controller can be adjusted to increase the driving frequency by a predetermined amount when the sensed input current exceeds a first boundary current if zero-voltage switching (ZVS) tracking is activated, decrease the driving frequency by a predetermined amount when the sensed input current is lower than or equal to the first boundary current and exceeds a second boundary current, and maintain the driving frequency when the sensed input current is lower than or equal to the second boundary current.

The above controller can repeatedly adjust the driving frequency until the adjusted driving frequency exceeds a predetermined threshold value.

The above controller can adjust the single-pole ratio by performing PI control using the output current and reference current when adjusting the single-pole ratio.

The steps of a method or algorithm described in connection with an embodiment of the present invention may be implemented directly in hardware, implemented as a software module executed by hardware, or implemented by a combination of these.

Above, while the embodiments of the present invention have been described with reference to the attached drawings, it will be understood by those skilled in the art that the present invention may be implemented in other specific forms without changing the technical idea or essential features thereof. Therefore, it should be understood that the embodiments described above are exemplary in all respects and not restrictive.

100: S-S compensation IPT based wireless power transfer device.

Claims (12)

As a wireless power transmission device based on SS(Series-Series) compensation IPT(inductive power transfer),
Full bridge based inverter for wireless power transmission;
A controller for setting the duty ratio and frequency of the above inverter;
The above inverter is connected to one end and an inductor-based SS compensation network; and
It includes a rectifier that is connected to the other end of the above SS compensation network and rectifies the transmitted AC power into DC.
The above controller,
When the output current output through the above rectifier is sensed and the input current is sensed, the unipolar duty cycle is adjusted based on the sensed output current, and the driving frequency is adjusted based on the sensed input current.
The above controller,
It is configured to independently adjust the above-mentioned single-pole ratio and the above-mentioned driving frequency,
A wireless power transmission device configured to activate zero-voltage switching (ZVS) tracking and constant current tracking, and to stop the unipolar duty cycle and the frequency adjustment when the sensed output current exceeds a threshold output current or the sensed input current exceeds a threshold input current. delete delete In the first paragraph,
The above controller,
A wireless power transmission device that, when ZVS (zero-voltage switching) tracking is activated, increases the driving frequency by a predetermined amount when the sensed input current exceeds the first boundary current, decreases the driving frequency by a predetermined amount when it is lower than the first boundary current and exceeds the second boundary current, and maintains the driving frequency when it is lower than the second boundary current. In paragraph 4,
The above controller,
A wireless power transmission device configured to repeatedly adjust a driving frequency until the adjusted driving frequency exceeds a predetermined threshold. In paragraph 5,
The above controller,
A wireless power transmission device configured to adjust the single-pole ratio by performing PI control using output current and reference current when adjusting the single-pole ratio. A control method for a wireless power transmission device based on SS(Series-Series) compensation IPT(inductive power transfer),
The wireless power transmission device comprises a full bridge-based inverter for wireless power transmission, a controller for setting the duty ratio and frequency of the inverter, an inductor-based SS compensation network connected to one end of the inverter and a rectifier connected to the other end of the SS compensation network and rectifying the transmitted AC power into DC.
The above control method is,
A step in which the output current output through the above rectifier is sensed and the input current is sensed; and
A step of adjusting the unipolar duty cycle based on the sensed output current and adjusting the driving frequency based on the sensed input current is included.
The above adjustment steps are:
Including a step of independently adjusting the above-mentioned single-pole ratio and the above-mentioned driving frequency,
The above control method is,
A method for controlling a wireless power transmission device, further comprising the steps of activating zero-voltage switching (ZVS) tracking and constant current tracking, and stopping the single-pole duty ratio and the frequency adjustment when the sensed output current exceeds a threshold output current or the sensed input current exceeds a threshold input current. delete delete In Article 7,
The above adjustment steps are:
A method for controlling a wireless power transmission device, comprising the steps of: when ZVS (zero-voltage switching) tracking is activated, if the sensed input current exceeds a first boundary current, increasing the driving frequency by a predetermined amount; when the sensed input current is lower than or equal to the first boundary current and exceeds a second boundary current, decreasing the driving frequency by a predetermined amount; and when the sensed input current is lower than or equal to the second boundary current, maintaining the driving frequency. In Article 10,
The above adjustment steps are:
A control method for a wireless power transmission device, comprising the step of repeatedly adjusting a driving frequency until the adjusted driving frequency exceeds a predetermined threshold value. In Article 11,
The above adjustment steps are:
A method for controlling a wireless power transmission device, comprising the step of adjusting the single-pole ratio by performing PI control using output current and reference current when adjusting the single-pole ratio.

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