CN104333067A - Wireless charging circuit - Google Patents

Abstract

The invention discloses a wireless charging circuit. The wireless charging circuit comprises a primary side circuit of a resonant inductor, a secondary side circuit of the resonant inductor and a control circuit, wherein the primary side circuit of the resonant inductor comprises a first diode full bridge rectifier, a high-frequency inverter circuit and a primary side resonant circuit of the resonant inductor; the secondary side circuit of the resonant inductor comprises a secondary side resonant circuit of the resonant inductor L1, an electronic capacitor circuit, a second diode full bridge rectifier circuit and a rechargeable battery E. The control circuit comprises a first voltage sensor, a second voltage sensor, an AD (Analog Digital) conversion module circuit, a DSP (Digital Signal Processor) control circuit and a PWM (Pulse Width Modulation) drive circuit. The circuit has a simple structure, the electronic capacitor circuit is equivalent to a variable capacitor, the resonant frequency of the circuit can be changed in real time according to different battery charging conditions, and the charging efficiency is improved.

Description

A wireless charging circuit

technical field

The invention relates to the technical field of wireless charging, in particular to a wireless charging circuit using an electronic capacitor circuit.

Background technique

The so-called wireless charging refers to the wireless transmission of electric energy by coupling with electromagnetic fields or other substances without cables. Wireless charging uses the principle of "resonance" in physics - two objects that vibrate at the same frequency can transfer energy efficiently. Wireless power transmission includes three common wireless charging methods: coupled inductive, electromagnetic resonance, and optical coupling. Among them, electromagnetic resonance can achieve relatively high efficiency and is widely used in various fields of the wireless charging industry.

Theoretically speaking, wireless charging technology is harmless to the safety of the human body. The resonance principle used in wireless charging is magnetic field resonance, which is only transmitted between coils that resonate at the same frequency, while other devices cannot accept the band. In addition, the wireless charging technology uses The magnetic field itself is harmless to the human body.

The improvement of the charging efficiency of the electromagnetic resonance method has always been a key research direction of domestic experts. The present invention makes up for some shortcomings of this method to a certain extent, and improves the efficiency of wireless charging.

With the rapid rise of "hungry" devices such as iPhones and iPads, there is an increasing demand for research and development of breakthrough charging technologies such as wireless charging. Fujitsu said in a statement: "This technology will pave the way for the integration of compact wireless charging functions in mobile phones and the simultaneous charging of multiple portable devices. When charging multiple devices, there are no restrictions on the position of the device relative to the charger. .” Therefore, wireless charging technology has a broad market prospect and application value.

Contents of the invention

The object of the present invention is to overcome the deficiencies of the prior art and provide a wireless charging circuit, which can be applied to charging mobile phone batteries, lithium ions on-board electric vehicles, and the like.

The present invention is realized through the following technical solutions.

A wireless charging circuit includes: a primary side circuit of a resonant inductor, a secondary side circuit of the resonant inductor, and a control circuit. The primary-side circuit of the resonant inductor includes: a first diode full-bridge rectifier circuit, a high-frequency inverter circuit, and a primary-side resonant circuit of the resonant inductor. The secondary side circuit of the resonant inductor includes: the secondary side resonant circuit of the resonant inductor, an electronic capacitor circuit, a second diode full-bridge rectifier circuit, and a rechargeable battery. The control circuit includes: a first voltage sensor, a second voltage sensor, an AD conversion module circuit, a DSP control circuit and a PWM drive circuit.

The input power AC generates DC voltage after passing through the first diode full-bridge rectifier circuit, and then generates high-frequency AC voltage through the high-frequency inverter circuit, and then passes through the resonant inductor, the energy is transmitted to the secondary side, and then traces the resonance through the electronic capacitor circuit Frequency, and finally through the second diode full-bridge rectifier circuit to charge the battery. The control circuit uses the first voltage sensor and the second voltage sensor to sample the voltage as an input, and the eight-way drive signals output by the control circuit control the action of the switch tube to achieve the highest charging efficiency.

Further, the first diode rectification circuit is composed of a first diode, a second diode, a third diode and a fourth diode, and the rectification circuit rectifies the commercial power, and its output passes through the first capacitor Stabilize and filter.

Further, the high frequency inverter circuit is composed of a first IGBT switch tube, a second IGBT switch tube, a third IGBT switch tube and a fourth IGBT switch tube. The collector of the first IGBT switch tube and the collector of the second IGBT switch tube are connected to the positive terminal of the first capacitor, the emitter of the first IGBT switch tube is connected to the collector of the third IGBT switch tube, and the second IGBT switch tube The emitter of the fourth IGBT switch is connected to the collector of the fourth IGBT switch, the emitter of the third IGBT switch and the emitter of the fourth IGBT switch are connected to the negative pole of the first capacitor; Perform inverter to generate 100kHz high-frequency alternating current.

Further, the primary side resonant circuit of the resonant inductor is composed of the third capacitor and the primary side of the resonant inductor connected in series, one end of the primary side resonant circuit is connected to the emitter of the first IGBT switch tube, and the other end of the primary side first resonant circuit Connected to the emitter of the second IGBT switch tube; the primary side of the resonant inductor flows through the positive and negative alternating high frequency alternating current in order to send energy to the secondary side of the resonant inductor; the secondary side resonant circuit of the resonant inductor is composed of The secondary side of the resonant inductor is connected in series with the electronic capacitor circuit.

Further, the electronic capacitance circuit is composed of a fifth IGBT switch tube, a sixth IGBT switch tube, a seventh IGBT switch tube, an eighth IGBT switch tube, a fifth diode, a sixth diode, a seventh diode, a Composed of eight diodes and the second capacitor; the gate control poles of the fifth IGBT switch tube, the sixth IGBT switch tube, the seventh IGBT switch tube and the eighth IGBT switch tube are all connected to a PWM drive circuit, and the four PWM The waveforms of the driving circuit are the same in pairs, the PWM waveforms connected to the gate electrodes of the fifth and eighth IGBT switches are the same, and the PWM waveforms connected to the gate electrodes of the sixth and seventh IGBT switches are The PWM waveforms are the same; the collector of the fifth IGBT switch, the collector of the sixth IGBT switch and the positive terminal of the second capacitor are connected; the emitter of the fifth IGBT switch is connected to the collector of the seventh IGBT switch; The emitter of the seventh IGBT switch tube, the emitter of the eighth IGBT switch tube are connected to the negative terminal of the second capacitor; the collector of the eighth IGBT switch tube is connected to the emitter of the sixth IGBT switch tube; the fifth diode , the sixth diode, the seventh diode and the eighth diode are connected in antiparallel to both ends of the fifth IGBT switch tube, the sixth IGBT switch tube, the seventh IGBT switch tube and the eighth IGBT switch tube; The emitter of the fifth IGBT switch tube and the emitter of the sixth IGBT switch tube each lead out a line as two ends of the electronic capacitor circuit.

Further, the second diode full-bridge rectifier circuit (the ninth diode, the tenth diode, the eleventh diode and the twelfth diode) conducts the voltage on the secondary side of the first resonant circuit rectification, the output passes through the fourth capacitor, and the obtained voltage charges the battery.

Further, the first voltage sensor and the second voltage sensor are respectively connected in parallel with both sides of the first capacitor and the third capacitor. The voltage obtained by sampling is used as the input of the AD conversion module circuit. The AD conversion module circuit is two summation circuits composed of a high-precision operational amplifier, which converts the sampled voltage to 0-3.3V for signal processing of the DSP chip.

Furthermore, the DSP control circuit is composed of a DSP chip and peripheral circuits. The voltage output by the AD conversion module circuit is sampled by the DSP control circuit to generate eight undriven PWM waveforms, and the eight undriven PWM waveforms are passed through the PWM After driving the circuit, they are respectively sent to the gate control electrodes of the designated IGBT switch tubes to control the on-off of the above-mentioned IGBT switch tubes.

Furthermore, the DSP control circuit is a control circuit composed of a DSP chip. The DSP control circuit converts the voltages sampled by the first voltage sensor and the second voltage sensor to a certain ratio, and the obtained values are used to generate eight different duty cycles. than the PWM waveform.

Further, the PWM drive circuit is composed of eight identical drive circuits composed of discrete components. The above eight PWM waveforms with different duty ratios are passed through the above eight drive circuits to obtain PWM1-PWM8, which drive the first IGBT switch tube to the eighth drive circuit respectively. IGBT switch tube.

When the circuit is working, first the alternating current AC is rectified and filtered by the first diode rectification circuit, then the high-frequency voltage is generated by the high-frequency inverter circuit, and the high-frequency voltage is transmitted to the secondary circuit through the primary side and secondary side circuit of the resonant inductor. Secondary side. Under the action of electronic capacitance, the capacitance value with the best efficiency can be found by controlling the actions of the four switching tubes of the electronic capacitance circuit. Finally, the battery is charged through the second diode rectification circuit.

Compared with the prior art, the present invention has the following advantages and technical effects:

Based on the equivalent principle of electromagnetic resonance and electronic capacitor circuit, the invention equates the electronic capacitor circuit into a variable capacitor, and changes the resonant frequency of the circuit in real time according to different charging conditions of the battery to improve charging efficiency. The circuit not only saves economic cost, but also improves charging efficiency, saves electric energy, and has good market prospect and economic benefits. The invention will be widely applied to wireless charging fields such as mobile phone battery charging and electric vehicle on-board lithium-ion charging. Improving the existing charging efficiency by improving wireless charging equipment can produce good economic and social benefits. the

Description of drawings

Figure 1 is the primary side circuit of the resonant inductance L1 of the wireless charging circuit;

Fig. 2 is the secondary side circuit of the resonant inductance L1 of the wireless charging circuit;

Fig. 3 is the control circuit of the wireless charging circuit;

FIG. 4 is a system diagram of a wireless charging circuit.

Detailed ways

The specific embodiment of the present invention will be further described below in conjunction with the accompanying drawings, but the implementation and protection scope of the present invention are not limited thereto. Achieved with technology.

FIG. 1 is a primary side circuit of the resonant inductor L1 of the wireless charging circuit.

The primary-side circuit of the resonant inductor L1 includes: a first diode full-bridge rectifier circuit, a high-frequency inverter circuit, and a primary-side resonant circuit of the resonant inductor L1. The first diode full-bridge rectification circuit is composed of the first diode VD1, the second diode VD2, the third diode VD3 and the fourth diode VD4. The rectification circuit rectifies the commercial power, and its output passes through The first capacitor C1 performs voltage stabilization and filtering.

The high frequency inverter circuit is composed of a first IGBT switch tube VT1, a second IGBT switch tube VT2, a third IGBT switch tube VT3 and a fourth IGBT switch tube VT4. The collector of the first IGBT switch tube and the collector of the second IGBT switch tube are connected to the positive terminal of the first capacitor, the emitter of the first IGBT switch tube is connected to the collector of the third IGBT switch tube, and the second IGBT switch tube The emitter of the fourth IGBT switch is connected to the collector of the fourth IGBT switch, the emitter of the third IGBT switch and the emitter of the fourth IGBT switch are connected to the negative pole of the first capacitor; Perform inverter to generate 100kHz high-frequency alternating current.

The primary side resonant circuit of the resonant inductor L1 is composed of the third capacitor C3 and the primary side of the resonant inductor L1 connected in series. One end of the primary side resonant circuit is connected to the emitter of the first IGBT switch tube, and the other end of the primary side first resonant circuit Connected to the emitter of the second IGBT switch tube; the primary side of the resonant inductor flows through the positive and negative alternating high-frequency alternating current in order to send energy to the secondary side of the resonant inductor; the secondary side resonant circuit of the resonant inductor L1 is It is composed of the secondary side of the resonant inductor and the electronic capacitor circuit in series.

After the commercial power is stabilized by the first diode rectifier circuit and the first capacitor, the obtained voltage is used as the input of the high-frequency inverter circuit, and the output after high frequency is used as the input of the primary side of the resonant circuit. The first capacitor C1 The terminal voltage is used as the input of the first voltage sensor. This part of the circuit mainly completes the rectification and inversion of the mains power, thereby generating high-frequency AC voltage and transferring energy from the primary side to the secondary side.

FIG. 2 is a secondary side circuit of the resonant inductor L1 of the wireless charging circuit.

The secondary side circuit of the resonant inductor L1 includes: a secondary side resonant circuit of the resonant inductor L1, an electronic capacitor circuit, a second diode full-bridge rectifier circuit, and a rechargeable battery E.

The electronic capacitor circuit consists of the fifth IGBT switch tube VT5, the sixth IGBT switch tube VT6, the seventh IGBT switch tube VT7, the eighth IGBT switch tube VT8, the fifth diode VD5, the sixth diode VD6, and the seventh diode Tube VD7, the eighth diode VD8 and the second capacitor C2; the gate control poles of the fifth IGBT switch tube, the sixth IGBT switch tube, the seventh IGBT switch tube and the eighth IGBT switch tube are all connected to a PWM drive Circuit, the waveforms of these four PWM drive circuits are the same in pairs, the PWM waveforms connected to the gate electrodes of the fifth IGBT switch tube and the eighth IGBT switch tube are the same, and the gates of the sixth IGBT switch tube and the seventh IGBT switch tube The PWM waveform connected to the gate is the same; the collector of the fifth IGBT switch, the collector of the sixth IGBT switch and the positive terminal of the second capacitor are connected; the emitter of the fifth IGBT switch and the seventh IGBT switch The collector of the seventh IGBT switch is connected; the emitter of the seventh IGBT switch, the emitter of the eighth IGBT switch are connected to the negative terminal of the second capacitor; the collector of the eighth IGBT switch is connected to the emitter of the sixth IGBT switch ; The fifth diode, the sixth diode, the seventh diode and the eighth diode are connected in antiparallel to the fifth IGBT switch tube, the sixth IGBT switch tube, the seventh IGBT switch tube and the eighth IGBT switch tube Two ends of the tube; one line is drawn from the emitter of the fifth IGBT switch tube and the emitter of the sixth IGBT switch tube as the two ends of the electronic capacitor circuit.

The second diode full-bridge rectification circuit (ninth diode VD1, tenth diode VD2, eleventh diode VD3 and twelfth diode VD4) rectifies the voltage on the secondary side of the resonant circuit , the output passes through the fourth capacitor C4, and the obtained voltage is charged to the battery.

The charging circuit receives the electric energy transmitted by the primary side through the resonant circuit composed of the secondary side of the resonant inductor and the electronic capacitor. After passing through the second diode full-bridge rectifier circuit and the fourth capacitor, the battery is charged, and the terminal voltage of the fourth capacitor C4 is used as the input of the second voltage sensor. This part of the circuit mainly completes the capacitance adjustment of the electronic capacitance circuit, so as to find a suitable resonance frequency.

Figure 3 is the control circuit of the wireless charging circuit.

The DSP control circuit is composed of a DSP chip and peripheral circuits. The output voltage of the AD conversion module circuit is sampled by the DSP control circuit to generate eight undriven PWM waveforms. After the eight undriven PWM waveforms pass through the PWM drive circuit , respectively sent to the gate control pole of the designated IGBT switch tube to control the on-off of the above-mentioned IGBT switch tube.

As an example, those skilled in the art can use the DSP control circuit to convert the voltages sampled by the first voltage sensor and the second voltage sensor to a certain ratio, and then generate eight channels of PWM waveforms with different duty ratios.

The PWM driving circuit is composed of eight identical driving circuits composed of discrete components. The above-mentioned eight-way PWM waveforms with different duty ratios are passed through the above-mentioned eight-way driving circuit to obtain PWM1-PWM8, which drive the first IGBT switch tube to the eighth IGBT switch tube respectively. .

The input of the control circuit is the output of the first voltage sensor and the second voltage sensor, and after the signal conditioning of the AD conversion module, it is input to the DSP for processing. One of the outputs of the DSP is directly used as the input of the eight-way PWM driving module, and one way is input to the eight-way PWM driving module after passing through the inverter. The output of the eight-way PWM driving module is eight-way PWM signals, which are used as driving signals for each switching tube.

FIG. 4 is a system diagram of a wireless charging circuit. The input power AC passes through the first diode full-bridge rectifier circuit to generate DC voltage, and then passes through the high-frequency inverter circuit to generate high-frequency AC voltage, and then passes through the resonant inductor L1, the energy is transmitted to the secondary side, and then traced by the electronic capacitor circuit Resonant frequency, and finally through the second diode full-bridge rectifier circuit to charge the battery. The control circuit uses the first voltage sensor and the second voltage sensor to sample the voltage as an input, and the eight-way drive signals output by the control circuit control the action of the switch tube to achieve the highest charging efficiency.

It can be seen from the above that those skilled in the art can realize the maximum efficiency of charging by using the above circuit and using the electronic capacitor circuit to track the resonance point of the charging circuit in real time. The invention can be widely applied to mobile phone battery charging, electric vehicle on-board lithium ion charging and other wireless charging fields. Improving the existing charging efficiency by improving wireless charging equipment can produce good economic and social benefits.

Claims (10)

1. A wireless charging circuit, characterized in that it includes: a primary side circuit of a resonant inductor, a secondary side circuit of a resonant inductor, and a control circuit; wherein the primary side circuit of the resonant inductor includes: a first diode full-bridge rectifier circuit, High-frequency inverter circuit, primary side resonant circuit of resonant inductor; secondary side circuit of resonant inductor includes: secondary side resonant circuit of resonant inductor, electronic capacitor circuit, second diode full-bridge rectifier circuit, rechargeable battery; control The circuit includes: a first voltage sensor, a second voltage sensor, an AD conversion module circuit, a DSP control circuit and a PWM drive circuit; the input power AC generates a DC voltage through a first diode full-bridge rectifier circuit, and then passes through a high-frequency inverter circuit Generate high-frequency AC voltage, transmit energy to the secondary side of the resonant inductor through the primary side of the resonant inductor, then track the resonant frequency through the electronic capacitor circuit, and finally charge the battery through the second diode full-bridge rectifier circuit; control The circuit uses the first voltage sensor and the second voltage sensor to sample the voltage as input, and the eight-way driving signals output by the control circuit control the action of the switch tube to achieve the highest charging efficiency. 2. A wireless charging circuit according to claim 1, wherein the first diode rectifier circuit is composed of a first diode, a second diode, a third diode and a fourth diode The rectification circuit rectifies the mains, and its output is stabilized and filtered by the first capacitor. 3. A wireless charging circuit according to claim 1, wherein the high-frequency inverter circuit is composed of a first IGBT switch tube, a second IGBT switch tube, a third IGBT switch tube, and a fourth IGBT switch tube; The collector of the first IGBT switch tube and the collector of the second IGBT switch tube are connected to the positive terminal of the first capacitor, the emitter of the first IGBT switch tube is connected to the collector of the third IGBT switch tube, and the second IGBT switch tube The emitter of the fourth IGBT switch is connected to the collector of the fourth IGBT switch, the emitter of the third IGBT switch and the emitter of the fourth IGBT switch are connected to the negative pole of the first capacitor; Perform inverter to generate 100kHz high-frequency alternating current. 4. A wireless charging circuit according to claim 1, characterized in that the primary side resonant circuit of the resonant inductor is composed of a third capacitor and the primary side of the resonant inductor connected in series, and one end of the primary side resonant circuit is connected to the first The emitter of the IGBT switch tube, the other end of the first resonant circuit on the primary side is connected to the emitter of the second IGBT switch tube; the primary side of the resonant inductance flows through a positive and negative alternating high-frequency alternating current in order to send energy to the resonance The secondary side of the inductance; the secondary side of the resonant inductor The resonant circuit is composed of the secondary side of the resonant inductor and the electronic capacitor circuit in series. 5. A wireless charging circuit according to claim 1, characterized in that the electronic capacitor circuit consists of a fifth IGBT switch tube, a sixth IGBT switch tube, a seventh IGBT switch tube, an eighth IGBT switch tube, and a fifth and second IGBT switch tube. pole tube, the sixth diode, the seventh diode, the eighth diode and the second capacitor; the fifth IGBT switch tube, the sixth IGBT switch tube, the seventh IGBT switch tube and the eighth IGBT switch tube The gate control poles of each gate are connected with a PWM drive circuit. The waveforms of these four PWM drive circuits are the same in pairs. The PWM waveforms connected to the gate control poles of the fifth IGBT switch tube and the eighth IGBT switch tube are the same. The PWM waveform connected to the gate control electrode of the switching tube and the seventh IGBT switching tube is the same; the collector of the fifth IGBT switching tube, the collector of the sixth IGBT switching tube are connected to the positive terminal of the second capacitor; the fifth IGBT switch The emitter of the tube is connected to the collector of the seventh IGBT switch tube; the emitter of the seventh IGBT switch tube, the emitter of the eighth IGBT switch tube are connected to the negative terminal of the second capacitor; the collector of the eighth IGBT switch tube connected to the emitter of the sixth IGBT switch tube; the fifth diode, the sixth diode, the seventh diode and the eighth diode are connected in antiparallel to the fifth IGBT switch tube, the sixth IGBT switch tube, The two ends of the seventh IGBT switch tube and the eighth IGBT switch tube; one line is drawn from the emitter electrode of the fifth IGBT switch tube and the emitter electrode of the sixth IGBT switch tube as the two ends of the electronic capacitor circuit. 6. A wireless charging circuit according to claim 1, characterized in that the second diode full-bridge rectifier circuit rectifies the voltage on the secondary side of the resonant circuit, and outputs the obtained voltage through the fourth capacitor to the battery Charge. 7. A wireless charging circuit according to claim 1, characterized in that, the first voltage sensor and the second voltage sensor are respectively connected in parallel to both sides of the first capacitor and the third capacitor; the voltage obtained by sampling is used as an AD conversion module circuit The input of the AD conversion module circuit is two summation circuits composed of operational amplifiers, which convert the sampled voltage to 0-3.3V, so as to facilitate the signal processing of the DSP chip. 8. A wireless charging circuit according to claim 1, characterized in that the DSP control circuit is composed of a DSP chip and peripheral circuits, and the voltage output by the AD conversion module circuit is sampled by the DSP control circuit to generate eight channels without charging. The driven PWM waveforms and the eight undriven PWM waveforms are sent to the gate control electrodes of the designated IGBT switch tubes after passing through the PWM drive circuit to control the on-off of the above-mentioned IGBT switch tubes. 9. A wireless charging circuit according to claim 1, characterized in that, after the DSP control circuit performs proportional conversion on the voltages sampled by the first voltage sensor and the second voltage sensor, the obtained values are used to generate eight different duty cycles than the PWM waveform. 10. A wireless charging circuit according to claim 1, characterized in that, the PWM driving circuit is eight identical driving circuits composed of discrete components, and eight PWM waveforms with different duty ratios are passed through the eight driving circuits to obtain PWM1-PWM8 drive the first to eighth IGBT switch tubes respectively.