CN103825467A - High frequency conversion circuit of charging system with impedance matching network - Google Patents

Abstract

The invention discloses a high frequency conversion circuit of a wireless charging system with an impedance matching network. The circuit comprises a MOS tube, a first inductor, a second inductor, a first capacitor, a second capacitor, the impedance matching network, a transmitting coil, a receiving coil, a rectification circuit, a DC-DC conversion circuit and a load. The high frequency conversion circuit realizes DC-AC conversion through the turn-on and the turn-off of the MOS tube, and realizes the soft switching of the MOS tube through the first capacitor. The impedance matching network can convert the load which is too large or too small into an appropriate load, so that the load matches a design circuit load. The transmitting coil and the receiving coil realize wireless power transmission. The rectification circuit and the DC-DC conversion circuit adjust power received by the receiving coil into power which can charge the load. The load is the equivalent load of a wireless charging device. The circuit provided by the invention has the advantages of simple structure and high DC-AC conversion efficiency, and can adapt to a wide load change range.

Description

There is the high frequency conversion circuit of the charging system of impedance matching network

Technical field

The invention belongs to wireless power transmission technical field, particularly there is the high frequency conversion circuit of the wireless charging system of impedance matching network.

Background technology

1894, attempt using the alternating current of 3kHz to traction electric car inductive power supply from M.Hutin and M.Leblanc, this may be first trial of powering to traction electric car with induction mode in the world.The sixties in 20th century, non-contact power was attempted in the power supply of implantable medical device.The eighties in 20th century, Inductive transmission obtained good theory study and practice aspect the wireless charging of electric automobile.The nineties in 20th century, the scholar of Auckland, NZL university is abundant and perfect ICPT(Inductively Coupled Power Transfer, ICPT) technology, i.e. induction coupling delivery of electrical energy.2005, the team of City University of Hong Kong succeeded in developing non-contact charge platform, significant to the development of wireless power transmission.2006, the researcher of the Massachusetts Institute of Technology (MIT) utilizes the resonance technique of physics successfully to light the bulb of a 60W with 40% efficiency apart from left and right at 2m, this experiment becomes another new breakthrough of wireless power transmission technology, and has started the upsurge of wireless power transmission research.

Wireless power transmission technology is a kind of delivery of electrical energy mode of wide application prospect, there is the advantages such as safe, reliable, flexible, convenient, day by day be subject to the attention of countries in the world, and be more and more widely used in the various places that are not suitable for or are inconvenient to use wire contact electric energy transmitting, as occasions such as implantable medical device, mobile electronic product, robot, rail electric car power supplies, and be expected to can aspect small-power electronic product wireless charging, replace traditional plug charging in the near future.

As the power amplification circuit of wireless power transmission, traditional linear power amplification circuit, as category-A, category-B, C class power amplification circuit, its technology is quite ripe, but the not high problem of these power amplification circuit ubiquity efficiency.The D class of switching mode, E class, DE class power amplification circuit have overcome the not high shortcoming of traditional power amplification circuit efficiency, make switching tube be operated on off state, have improved the conversion efficiency of power amplification circuit.But existing research is just simply applied to radio energy transmission system the power amplification circuit of these types, the impact of impedance mismatch on efficiency while not considering load variations.Particularly, for the power amplification circuit of switching mode, although have advantages of that efficiency is high, the variation of load easily causes circuit to lose the function of soft switch, causes switching tube heating serious, so that burns out switching tube.

The type of the wireless power transmission radiating circuit of the applicable wide load variations scope of conduct or fewer at present, and impedance match technique is just applied to the wireless power transmission of RF application, be therefore necessary to propose the problem of the wide load variations scope of a kind of new technology solution wireless charging system.

Summary of the invention

The object of the invention is to overcome above-mentioned the deficiencies in the prior art, the high frequency conversion circuit of the wireless charging system with impedance matching network is provided.

The present invention is achieved through the following technical solutions:

There is the high frequency conversion circuit of the wireless charging system of impedance matching network, comprise a metal-oxide-semiconductor, the first inductance, the second inductance, the first electric capacity, the second electric capacity, impedance matching network, transmitting coil, receiving coil, rectification circuit, DC-DC translation circuit and load.

The high frequency conversion circuit of the above-mentioned wireless charging system with impedance matching network, metal-oxide-semiconductor internal structure comprises antiparallel diode; The first Capacitance parallel connection, at the two ends of metal-oxide-semiconductor, is realized the soft switch of metal-oxide-semiconductor.

The high frequency conversion circuit of the above-mentioned wireless charging system with impedance matching network, one end of the first inductance is connected with one end of the source electrode of metal-oxide-semiconductor, the second inductance, and the other end is connected with the negative pole of direct voltage source; The other end of the second inductance is connected with one end of the second electric capacity; The other end of the second electric capacity is connected with impedance matching network; Impedance matching network connects the radiating portion of transmitting coil formation wireless charging system; Receiving coil connects and composes receiving unit successively with rectification circuit, DC-DC translation circuit respectively, and to load R _lcharge.

Compared with prior art, tool of the present invention has the following advantages:

1, adopt the high frequency conversion circuit structure of switching mode, the principle design occurring when different according to voltage, electric current, DC-AC conversion efficiency is high, and theoretical efficiency reaches 100%.

2, the high frequency conversion circuit of the described wireless charging system with impedance matching network only has a metal-oxide-semiconductor, and circuit structure is simple, and control circuit is easily realized.

3, the high frequency conversion circuit of the described wireless charging system with impedance matching network has the function of impedance matching, can realize wide load variations scope.

Accompanying drawing explanation

Fig. 1 is structural representation of the present invention.

Fig. 2 is the physical circuit figure of embodiment of the present invention.

The voltage waveform at load two ends in Fig. 3 a～Fig. 3 c difference Fig. 2, the electric current of metal-oxide-semiconductor, voltage waveform.

Fig. 4 a～Fig. 4 c is respectively while not adding match circuit the voltage waveform at load two ends in Fig. 2, the electric current of metal-oxide-semiconductor, voltage waveform.

specific embodiments

Below in conjunction with accompanying drawing, the concrete enforcement of invention is further described, but enforcement of the present invention and protection are not limited to this.

Shown in Fig. 1, there is in the high frequency conversion circuit of wireless charging system of impedance matching network the first inductance L ₀one end and source electrode, the second inductance L of metal-oxide-semiconductor S ₁one end connect, the other end and direct voltage source V _innegative pole connect; The second inductance L ₁the other end and the second capacitor C ₁one end connect; The second capacitor C ₁the other end be connected with impedance matching network; Impedance matching network connects the radiating portion of transmitting coil formation wireless charging system; Receiving coil connects and composes receiving unit successively with rectification circuit, DC-DC translation circuit respectively, and to load R _lcharge.

Embodiment

Fig. 1 is structural representation of the present invention.Fig. 2 is the physical circuit figure of embodiment of the present invention.Impedance matching network mates as example, with L take simple L-type _mand C _mrepresent.Transmitting coil is equivalent to former limit inductance L _pwith former limit capacitor C _pseries connection, receiving coil is equivalent to secondary inductance L _sc with secondary electric capacity _sseries connection, ignore the internal resistance loss of transmitting coil and receiving coil.Rectification circuit is full bridge rectifier.In Fig. 2, omit DC-DC translation circuit link.

The basic parameter of the present embodiment circuit is as shown in table 1.

Table 1

Parameter	Value	Parameter	Value
				Input voltage: V in	12V	Matching capacitance: C m	11.13nF
Operating frequency: f	1MHz	Former limit inductance: L P	12μH
				The first inductance: L 0	120μH	Former limit electric capacity: C P	2.1nF
The first electric capacity: C 0	3.79nF	Secondary inductance: L S	12μH
				The second inductance: L 1	11.84μH	Secondary electric capacity: C S	2.1nF
The second electric capacity: C 1	2.48nF	Mutual inductance: M	1.2μH

Coupling inductance: L m

1.11μH

Build-out resistor: R

7.15Ω

In the present embodiment, be charged as example with mobile phone, charging voltage is 5V, and charging current is 1A, and equivalent load is 5 Ω.According to exchanging the principle of equal effects, for the series resonant converter of current source type, DC side load R _lequivalence to the AC resistance of AC is:

$R_{\mathrm{eq}}=\frac{8}{{\mathrm{\π}}^2}{R}_L$

And secondary reflexes to the resistance on former limit, need the resistance R of coupling _mfor:

$R_m=\frac{{\mathrm{\ω}}^2{M}^2}{R_{\mathrm{eq}}}$

In formula, ω is angular frequency and ω=2 π f, and M is mutual inductance.Due to load resistance R _l=5 Ω, AC resistance R _eq=4.05 Ω, needing the resistance of coupling is R _m=14 Ω.Due to build-out resistor R=7.15 Ω, therefore can mate the resistance R of needs coupling by L-type _mmatch build-out resistor R.Match parameter can be calculated thus as shown in table 1.

Fig. 3 a is the voltage waveform at load two ends in Fig. 2.Fig. 3 b and Fig. 3 c are respectively electric current, the voltage waveform of metal-oxide-semiconductor S in Fig. 2.Can find out the sine wave that load voltage waveform is standard from Fig. 3 a.Can find out from Fig. 3 b and Fig. 3 c, metal-oxide-semiconductor S has realized soft switch, with conforming to of design.Further, metal-oxide-semiconductor S electric current while not adding impedance matching network, voltage waveform are as shown in Fig. 4 b and Fig. 4 c, as seen from the figure, owing to not adding impedance matching network, output voltage is less than while adding impedance matching network, and in the time that switching tube turn-offs, there is current spike, fail to realize voltage zero derivative open-minded.Therefore, verified that the present invention is applied to the validity of wireless charging system.

Claims (3)

1. there is the high frequency conversion circuit of the wireless charging system of impedance matching network, it is characterized in that comprising a metal-oxide-semiconductor (S), the first inductance ( l ₀), the second inductance ( l ₁), the first electric capacity ( c ₀), the second electric capacity ( c ₁), impedance matching network, transmitting coil, receiving coil, rectification circuit, DC-DC translation circuit and load ( r _l); The first inductance ( l ₀) one end and the source electrode of metal-oxide-semiconductor (S), the second inductance ( l ₁) one end connect, the other end and direct voltage source ( v _in) negative pole connect; The second inductance ( l ₁) the other end and the second electric capacity ( c ₁) one end connect; The second electric capacity ( c ₁) the other end be connected with impedance matching network; The first electric capacity ( c ₀) be connected in parallel on the two ends of metal-oxide-semiconductor (S), realize the soft switch of metal-oxide-semiconductor (S); Impedance matching network connects the radiating portion of transmitting coil formation wireless charging system; Receiving coil and rectification circuit, DC-DC translation circuit connect and compose receiving unit successively, and to load ( r _l) charge.

2. the high frequency conversion circuit of the wireless charging system with impedance matching network according to claim 1, is characterized in that described metal-oxide-semiconductor (S) internal structure comprises antiparallel diode (D).

3. the high frequency conversion circuit of the wireless charging system with impedance matching network according to claim 1, is characterized in that described impedance matching network is L-type, CLC type and LCL type matching network.

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