Wireless power transmission system based on matrix converter

Abstract

The present invention provides a wireless power transmission system based on a matrix converter, including a three-phase AC input power supply, an LC filter, a three-phase-single-phase matrix converter, an S-S type compensation network, a coupling coil, a rectifier module, a load, a voltage and current acquisition module, and a DSP controller. The main circuit includes an LC filter, a three-phase-single-phase matrix converter module, a coupling coil, an S-S type compensation network, a rectifier module, and a load. The control circuit includes a three-phase voltage acquisition module, a current acquisition module, and a DSP controller. The DSP controller receives signals from the voltage and current acquisition modules, generates 12 drive signals according to a modulation strategy, and transmits the drive signals to the matrix converter. The present invention uses a three-phase-single-phase matrix converter for power modulation, eliminates the electrolytic capacitors connected in parallel on the DC bus, improves the reliability and life of the system, has a compact structure, a higher power density, and reduces hardware costs.

Description

Technical Field

[0001] The invention belongs to the technical field of wireless power transmission, and in particular relates to a wireless power transmission system based on a matrix converter. Background Art

[0002] Wireless power transmission systems are increasingly being used, thanks to their ability to safely and efficiently transmit electrical energy to loads in a contactless manner. Users do not need to connect devices with traditional charging cables, and can achieve wireless charging by simply placing the device in a specific location. Wireless power transmission systems are highly reliable because they reduce the risk of sparks in wired cables and avoid wear and tear caused by plugging and unplugging wired devices. Wireless power transmission technology can transmit electricity safely, cleanly and flexibly, and effectively cope with harsh environments such as rain, snow, and dust. Wireless power transmission systems are used to varying degrees in electric vehicles, biomedicine, household appliances, and drones, bringing convenience to people's lives. In the future, wireless power transmission will become a trend, and humans will move towards the wireless era. As an environmentally friendly and low-carbon means of transportation, electric vehicles have abundant power resources that can effectively cope with increasingly severe energy and environmental problems. However, range and charging time are still important factors limiting the popularization of electric vehicles. To solve this problem, by installing wireless power transmission equipment in parking lots or on roads, electric vehicles can be wirelessly charged while driving, which improves the convenience and range of electric vehicles. The development of wireless power transmission technology provides important support for the popularization and sustainable development of electric vehicles. The Society of Automotive Engineers' standards for wireless charging of electric vehicles are widely referenced, promoting the research and standardization of electric vehicles.

[0003] In a loosely coupled wireless power transmission system, in order to transfer energy from the outside of the vehicle through the air gap to the receiving end inside the vehicle, the inductive link needs to generate a strong magnetic field to improve the power transmission capacity. The coupling coil transmits power through the magnetic field generated by the high-frequency AC power, so it is necessary to convert the industrial frequency AC power into high-frequency AC power. At present, wireless power transmission systems are usually powered by a single-phase AC power grid. Typical wireless power transmission systems mostly use an AC-DC-AC two-stage conversion structure. In the first stage structure, the rectifier module is used to maintain a stable DC bus voltage and high-quality current output. In the second stage structure, the DC-AC inverter generates high-frequency AC power for wireless power transmission. This two-stage conversion structure leads to an increase in the number of power devices, increased energy loss during the conversion process, and the need for expensive energy storage components. Summary of the invention

[0004] In view of this, the present invention aims to overcome the deficiencies of the above-mentioned problems in the prior art and proposes a wireless power transmission system based on a matrix converter.

[0005] To achieve the above object, the technical solution of the present invention is achieved as follows:

[0006] The wireless power transmission system based on the matrix converter includes a three-phase AC input power supply, an LC filter, a three-phase-single-phase matrix converter, a transmitting device, a receiving device, a rectifier module, a load, a three-phase voltage acquisition module, a current acquisition module and a DSP controller. The three-phase power grid filters out high-order harmonics in the input current through an LC low-pass filter and is directly connected to the three-phase-single-phase matrix converter. The DSP controller receives signals collected by the three-phase voltage acquisition module and the current module, generates a driving signal according to a modulation strategy, and transmits the driving signal to the three-phase-single-phase matrix converter. The three-phase-single-phase matrix converter performs power modulation on the industrial frequency AC power of the three-phase power grid through a modulation strategy to achieve switching between an energy injection state and a free oscillation state, and outputs a high-frequency controllable current. The high-frequency AC current output by the three-phase-single-phase matrix converter generates an alternating magnetic field through a transmitting device, and transmits electric energy to the receiving device through coil coupling. The high-frequency AC power of the receiving device is converted into DC power through a rectifier module to drive the load.

[0007] Furthermore, the three-phase-single-phase matrix converter includes six bidirectional switches, each of which is composed of two MOSFETs with common sources connected in series.

[0008] Furthermore, the transmitting device includes a primary transmitting coil and a primary compensation capacitor, and the receiving device includes a secondary receiving coil and a secondary compensation capacitor.

[0009] Furthermore, the modulation strategy is used to modulate the amplitude of the resonant current. By detecting the amplitude of the resonant current and comparing it with the set current value, the combination logic of the switch is determined, so that the circuit enters an energy injection state or a free oscillation state. In the energy injection state, the three-phase-single-phase matrix converter injects grid energy into the circuit to increase the current amplitude. In the free oscillation state, the three-phase-single-phase matrix converter forms a free oscillation loop, the current flows in the loop, and the current amplitude decreases. If there is no energy consumption in the circuit, the current oscillates with equal amplitude.

[0010] Furthermore, the modulation strategy divides the working modes of the three-phase-single-phase matrix converter into 12 types according to the current direction, peak current and three-phase voltage state. According to the flow direction of the resonant current, each cycle of the resonant current is divided into a positive half-cycle and a negative half-cycle. When the current passes through zero, it is determined whether the circuit needs energy injection based on the peak current signal and current direction collected in the first half cycle. If the absolute value of the peak current signal is less than the set current value and the current direction is negative, energy needs to be injected in the next positive half cycle to enter the energy injection working mode. If the current direction is positive or the absolute value of the peak current signal is greater than the set current value, energy does not need to be injected, and the circuit oscillates freely. When entering the free oscillation working mode, the voltage input to the circuit each time is the maximum line voltage of the three-phase power supply at this time. Each working mode starts when the current passes through zero and continues until the next current passes through zero. High-frequency current output is achieved through combined modulation of switches.

[0011] Furthermore, a driving circuit is provided between the DSP controller and the three-phase-single-phase matrix converter.

[0012] Furthermore, the current acquisition module includes a current Hall sensor and a current signal acquisition circuit. The current signal acquisition circuit adopts a dual-channel comparator, channel one is used as a zero-crossing comparison circuit, and channel two is used for current amplitude detection.

[0013] Compared with the prior art, the wireless power transmission system based on the matrix converter described in the present invention has the following advantages:

[0014] (1) Through the modulation strategy of the present invention, the three-phase-single-phase matrix converter performs power modulation on the three-phase industrial frequency AC power on the grid side, realizes the switching of the circuit between the energy injection state and the free oscillation state, directly outputs high-frequency controllable current, does not require a DC bus electrolytic capacitor, can adjust the resonant current, reduces the number of power switch operations, makes the power switch tube work in a zero-current soft switching state, reduces the switch on-off loss, improves the transmission efficiency of the system, and the transmitting coil transmits the electric energy to the receiving coil through the high-frequency current to complete the wireless power transmission;

[0015] (2) The present invention uses a three-phase-single-phase matrix converter for power modulation, eliminating the DC bus electrolytic capacitor, reducing the impact of the DC side electrolytic capacitor on the system, improving the reliability and life of the system, with a compact structure and higher power density, further reducing the difficulty and cost of practical application;

[0016] (3) In the modulation strategy of the present invention, the working modes of the matrix converter are divided into 12 types according to the direction, amplitude and three-phase voltage state of the resonant current in the current, and the resonant current amplitude is compared with the set current value to determine the combination logic of the power switch, so that the circuit is in the energy injection state and the free oscillation state. The set current value can be changed to adjust the output current amplitude and output power. It has good stability and current waveform and is suitable for dynamic wireless power transmission systems. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The accompanying drawings constituting a part of the present invention are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the accompanying drawings:

[0018] Figure 1 A topological structure diagram of a wireless power transmission system based on a matrix converter of the present invention;

[0019] Figure 2 is an equivalent circuit diagram of the SS type compensation topology structure of the present invention;

[0020] Figure 3 A schematic diagram of a wireless power transmission system based on a matrix converter according to the present invention;

[0021] Figure 4 The circuit diagram of the three-phase-single-phase matrix converter of the present invention;

[0022] Figure 5 This is a current signal acquisition circuit diagram of the present invention. DETAILED DESCRIPTION

[0023] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments may be combined with each other.

[0024] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", and the like are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, features defined as "first", "second", and the like may explicitly or implicitly include one or more of the features. In the description of the present invention, unless otherwise specified, "multiple" means two or more.

[0025] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood by specific circumstances.

[0026] The present invention will be described in detail below with reference to the accompanying drawings and in conjunction with embodiments.

[0027] Figure 1 The topology of the three-phase-to-single-phase matrix converter wireless power transmission system is shown. The system is mainly composed of a three-phase AC input power supply, an LC filter, a three-phase-to-single-phase matrix converter, an SS-type compensation network, a coupling coil, a rectifier module and a load. The three-phase-to-single-phase matrix converter is composed of 6 bidirectional switches, each of which is composed of two MOSFETs connected in series with the common source. One end of the three-phase-to-single-phase matrix converter is connected to the three-phase input power supply, and the other end is directly connected to the coupling mechanism. No DC bus electrolytic capacitor is used, and bidirectional power transmission is allowed. The SS-type compensation network means that the coils and compensation capacitors at the transmitting and receiving ends are connected in series. In the figure, V a 、V b 、V c is the three-phase voltage, i L and i s Represents the primary current and secondary current respectively. L1 is the primary transmitting coil, L2 is the secondary receiving coil. C1 and C2 are the compensation capacitors of the primary and secondary coils respectively, R L is the load resistance.

[0028] The three-phase grid uses an LC low-pass filter to filter out the high-order harmonics in the input current, and then directly connects to the three-phase-to-single-phase matrix converter. The three-phase-to-single-phase matrix converter uses a modulation strategy to modulate the power frequency AC power of the three-phase grid, realizes the switching between the energy injection state and the free oscillation state, and outputs a high-frequency controllable current. The high-frequency AC current output by the three-phase-to-single-phase matrix converter generates an alternating magnetic field through the transmitting coil, and transmits the electrical energy to the secondary circuit through coil coupling. The high-frequency AC power of the secondary circuit is converted into DC power through the diode rectifier circuit to drive the load R L .

[0029] Figure 2 This is the equivalent circuit of the SS type compensation topology. Figure 2In the equation, ω represents the resonant angular frequency, j represents the imaginary part, -jωMi2 represents the induced voltage from the secondary coil to the primary coil through mutual inductance coupling, and jωMi1 represents the induced voltage from the primary coil to the secondary coil through mutual inductance coupling. g represents the output voltage of the three-phase-single-phase matrix converter, i1 and i2 represent the current of the primary and secondary sides respectively, L1 and L2 represent the self-inductance of the transmitting coil and the receiving coil, M represents the mutual inductance, R1 and R2 represent the internal resistance of the coil, C1 and C2 represent the compensation capacitance of the primary and secondary coils, R L is the load resistance.

[0030] The equivalent impedance Z1 of the primary circuit can be expressed as:

[0031]

[0032] The equivalent impedance Z2 of the secondary circuit is expressed as:

[0033]

[0034] Assume that the equivalent impedance of the secondary circuit mapped to the primary circuit is Z3, which can be expressed as:

[0035]

[0036] The total equivalent impedance Z of the circuit in for:

[0037] Z in =Z1+Z3(4)

[0038] By introducing compensation capacitors, the system can be put into a resonant state, the coupling ability of the transmitting coil and the receiving coil can be enhanced, and the transmission performance of the system can be improved. Therefore, both the primary circuit and the secondary circuit should be in a resonant state. When the resonant angular frequency and the coil inductance are determined, the primary compensation capacitor C1 and the secondary compensation capacitor C2 can be calculated. When the primary circuit is resonant, C1 is expressed as:

[0039]

[0040] When the secondary circuit is resonant, C2 is expressed as:

[0041]

[0042] From formula (2) and formula (3), the primary current i1 and the secondary current i2 can be calculated:

[0043]

[0044] From formula (7), we can get the output power P out The expression is:

[0045]

[0046] By using formula (7), the input power P can be calculated in , then according to formula (8), the expression of system transmission efficiency can be obtained as:

[0047]

[0048] The resonant frequency f of the system can be expressed as:

[0049]

[0050] According to formula (8) and formula (9), when the system is in the resonant state, the total equivalent impedance Z of the circuit is in The minimum, the highest power transmission efficiency. The resonant frequency of the circuit can be determined by formula (10). According to formula (5) and formula (6), when the resonant angular frequency is constant, the primary and secondary compensation capacitors are only related to the inductance of the coil. When the load resistance or coupling coefficient changes, the compensation network can still maintain the resonant state with the coil.

[0051] Figure 3 The figure is a schematic diagram of the wireless power transmission system of the three-phase-single-phase matrix converter. The main circuit includes an LC filter, a three-phase-single-phase matrix converter module, a coupling coil, a rectifier module and a load. The control circuit includes a three-phase voltage acquisition module, a current acquisition module and a DSP controller. The DSP controller receives the signals collected by the three-phase voltage acquisition module and the current acquisition module, generates 12 drive signals according to the modulation strategy, and transmits the drive signals to the three-phase-single-phase matrix converter. First, the resonant current is detected using the current acquisition module, and the current acquisition module transmits the zero-crossing signal and the amplitude signal to the DSP controller. When the resonant current passes zero, the DSP controller detects the input three-phase voltage, and modulates the switch according to the current amplitude signal and the three-phase voltage signal to generate twelve drive signals. The drive signal is generated according to the modulation strategy of Table 1, and then drives the bidirectional switch. The drive signal will be maintained until the next time the current passes zero, and the switching frequency of the three-phase-single-phase matrix converter is the same as the resonant frequency of the current.

[0052] The main purpose of the modulation strategy is to modulate the amplitude of the resonant current. By detecting the amplitude of the resonant current and setting the current value I refCompare and determine the combination logic of the switch, so that the circuit enters the energy injection state or the free oscillation state. In the energy injection state, the three-phase-single-phase matrix converter injects grid energy into the circuit to increase the current amplitude. In the free oscillation state, the three-phase-single-phase matrix converter will form a free oscillation loop, the current flows in the loop, and the current amplitude decreases. If there is no energy consumption in the circuit, the current can oscillate with equal amplitude. But in fact, due to the existence of equivalent resistance, power loss always exists. If no energy is injected into the circuit, the current will decay exponentially. Therefore, injecting energy into the circuit at the appropriate time can maintain high-frequency resonant current. By alternating between these two states, the current is controlled at the set current value I ref nearby.

[0053] The three-phase-single-phase matrix converter of the present invention has twelve operating modes, depending on the current direction i d , peak current i p And the three-phase voltage state V ab 、V bc and V ca Table 1 shows the switch status and control signals in different working modes. According to the flow direction of the resonant current, each cycle of the resonant current is divided into a positive half cycle and a negative half cycle. When the current passes through zero, according to the peak current signal (i p ) and the current direction (i d ) to determine whether the circuit needs energy injection. p The absolute value is less than I ref (i p =0) and the current direction is negative (i d =0), energy needs to be injected in the next positive half cycle. At this time, according to the state of the three-phase voltage, one of the working modes 1-6 will be entered. If the direction of the current is positive (i d =1) or i p The absolute value is greater than I ref (i P =1), then no energy injection is required and the circuit oscillates freely. According to the state of the three-phase voltage, one of the working modes 7-12 is entered. Each time the voltage input to the circuit is the maximum line voltage of the three-phase power supply at that time. Therefore, compared with the single-phase input source, the three-phase power supply can keep the input voltage at a higher level. Each working mode starts from the current zero crossing point and continues until the next current zero crossing point, and high-frequency current output is achieved through the combined modulation of the switch.

[0054] Table 1

[0055]

[0056] The meaning of the variables in Table 1: i d =1 means current iL The flow direction is the positive direction, i d =0 means current i L The direction is opposite to the specified direction, i P =1 indicates the peak value of the resonant current i P Greater than the set current value I ref ,i P =0 indicates the peak value of the resonant current i P Less than the current setting value I ref , V ab =1 means phase voltage V a Greater than phase b voltage V b , V ab =0 means phase voltage V a Less than phase b voltage V b , variable V bc and V ca Similarly, switch S1 represents switch S a1 and switch S b1 The same applies to other switch signals.

[0057] Figure 4 The circuit diagram of the three-phase to single-phase matrix converter is shown in Figure 1. The driver chip receives the drive signal generated by the DSP controller and then converts it into a high-power drive signal S a1 and S b1 When S b1 When it is high level, PNP transistor Q4 is turned off, the difference between the gate voltage and the source voltage of MOSFET switch is greater than the threshold voltage, and switch tube Q1 is turned on. b1 When switched to a low level, the gate voltage of Q1 does not change immediately, the PNP transistor Q4 is turned on, the gate and source of the MOSFET are partially short-circuited, and the gate voltage drops rapidly, which can quickly turn off the MOSFET. Since the drive circuit and the DSP controller are electrically isolated, the shutdown current does not return to the DSP controller, which will not cause the switch tube to be mis-turned on.

[0058] The present invention uses a MOSFET common source series bidirectional switch to form a three-phase-single-phase matrix converter, and the control circuit controls the switch tube of the three-phase-single-phase matrix converter to achieve high-frequency controllable current output. The MOSFET of the three-phase-single-phase matrix converter is an N-channel field effect tube IXFH160N15T2 produced by IXYS.

[0059] The driving signal power output by the DSP controller is relatively small, and its driving voltage and current are not enough to turn on the switch tube, so it is necessary to design a driving circuit to increase the driving power. The driving circuit can provide enough driving power to make the switch tube turn on and off quickly to ensure its good working state. When designing the driving circuit, it is also necessary to consider the operating frequency, driving power and electrical isolation. In view of the fact that the input of the main circuit of the present invention is a three-phase power supply, in order to prevent the main circuit from interfering with the control circuit, it is necessary to electrically isolate the main circuit and the driving circuit to improve the stability of the control circuit. Considering the operating frequency of the system, the driving circuit must ensure that the on-off speed of the switch tube meets the experimental requirements. The output voltage of the driving circuit must be higher than the threshold voltage of the MOSFET, which is generally 10-15V. MOSFET is a voltage-driven device, so the driving circuit is required to provide enough driving voltage. In addition, in order to ensure the switching speed of the MOSFET, the driving circuit also needs to provide a certain peak current.

[0060] The driving circuit of the present invention uses the digital isolation driver chip SI8235BD-D-IS of Silicon Labs. This chip integrates two independent and isolated drivers in one package and adopts the silicon isolation technology independently developed by Silicon Labs to achieve an input and output isolation voltage of up to 5000V, which can effectively prevent the main circuit from interfering with the control circuit. Through the DSP controller, according to the modulation strategy, the circuit state is adjusted to achieve direct AC-AC conversion.

[0061] According to the modulation strategy, the three-phase-single-phase matrix converter needs to switch the working mode according to the signals of the three-phase voltage and the resonant current. When the current passes through zero, the DSP controller collects the three-phase voltage signal and the current amplitude signal. The DSP controller converts the collected voltage signal into a digital quantity through the ADC module. The model of the DSP controller used in the present invention is TMS320F28335, and the ADC module safety input voltage of the controller is 0-3V. Therefore, before collecting the voltage and current signals, the signal to be measured needs to be conditioned into a voltage signal that can be read by the ADC module. In order to prevent high voltage or high current signals from damaging the controller, electrical isolation is required.

[0062] Since it is difficult to accurately collect current amplitude signals and zero-crossing signals through a DSP controller, a high sampling rate ADC module is required, and the response speed of the controller will be reduced, affecting the control accuracy. Therefore, the present invention uses a comparison circuit to detect the zero-crossing signal and amplitude signal of the current. When the current passes through zero, the DSP controller only needs to collect three-phase voltage signals. The amplitude signal and zero-crossing signal generated by the comparison circuit are transmitted to the DSP controller to improve the processing speed and control accuracy of the DSP controller. The present invention uses a comparator model LT1715CMS to complete current zero-crossing detection and amplitude detection. The DSP controller collects zero-crossing signals and amplitude signals, and according to the modulation strategy, the logical combination of the modulation switches to achieve high-frequency current output, such as Figure 5 Shown is a current signal acquisition circuit diagram. Since the resonant current frequency in the circuit is relatively high, generally tens of kilohertz, a comparator with a fast response speed is required to generate a rising edge or a falling edge to trigger the controller when performing a zero-crossing comparison. The present invention uses a comparator model LT1715CMS. The LT1715CMS comparator is a dual-channel high-speed comparator suitable for low voltages. It has a fast response time of 2ns and a maximum switching frequency of up to 150MHz. It has two independent comparison channels (Channel A and Channel B), uses independent input and output power supplies, and the output is compatible with TTL levels to meet experimental requirements. The present invention selects Channel A as the zero-crossing comparison circuit. Figure 5 In the figure, Current is used to represent the output voltage of the current Hall sensor.

[0063] Comparator A compares the output signal Current of the current Hall sensor with the reference voltage signal V when the current passes through zero point. ref Compare and convert to square wave signal with the same frequency. The reference voltage V when crossing zero ref Take V CC / 2. When the input voltage Current is less than V ref OUTA outputs high level. When Current is greater than V ref Then, an inverter of model SN74LVCIG14DBV is used to convert the square wave signal into a square wave signal with the same frequency and phase as the actual current.

[0064] The present invention uses an amplitude detection circuit to collect the current amplitude. Since the focus is on the relationship between the actual current amplitude and the set current value, the precise current amplitude value is not required. Therefore, the present invention uses channel B of the comparator LT1715CMS to detect the current amplitude. The sine wave voltage signal Current generated by the current Hall sensor is compared with the reference voltage V corresponding to the set current value. ampComparison is used to realize amplitude detection. According to the modulation strategy, the current amplitude detection is performed in the negative half cycle of the current. The voltage signal Current is connected to the inverting input of comparator channel B. If Current is lower than V amp When Current is higher than V amp When the actual current amplitude is lower than the set value, OUTB outputs a low level. The DSP controller collects the signal of OUTB to complete the detection of the amplitude signal.

[0065] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A wireless power transmission system based on a matrix converter, characterized in that: It includes a three-phase AC input power supply, an LC filter, a three-phase-to-single-phase matrix converter, a transmitter, a receiver, a rectifier module, a load, a three-phase voltage acquisition module, a current acquisition module and a DSP controller. The three-phase industrial frequency AC power of the power grid is connected, and the high-order harmonics in the input current are filtered out by an LC low-pass filter, and the power grid is directly connected to the three-phase-to-single-phase matrix converter. The DSP controller receives signals from the three-phase voltage acquisition module and the current acquisition module, generates a driving signal according to a modulation strategy, and transmits the driving signal to the three-phase-to-single-phase matrix converter. The three-phase-to-single-phase matrix converter performs power modulation on the industrial frequency AC power of the three-phase power grid through the modulation strategy to achieve switching between an energy injection state and a free oscillation state, and outputs a high-frequency controllable current. The high-frequency AC current output by the three-phase-to-single-phase matrix converter generates an alternating magnetic field through the transmitter, and transmits electric energy to the receiving device through coil coupling resonance. The high-frequency AC power of the receiving device is converted into DC power through the rectifier module to drive the load. The three-phase-single-phase matrix converter includes six bidirectional switches, each of which is composed of two MOSFETs connected in series with their common sources; The modulation strategy is used to modulate the amplitude of the resonant current. By detecting the amplitude of the resonant current and comparing it with the set current value, the combination logic of the switch is determined, so that the circuit enters the energy injection state or the free oscillation state. In the energy injection state, the three-phase-single-phase matrix converter injects grid energy into the circuit to increase the current amplitude. In the free oscillation state, the three-phase-single-phase matrix converter forms a free oscillation loop, and the current flows in the loop, and the current amplitude decreases. If there is no energy consumption in the circuit, the current oscillates with equal amplitude; The modulation strategy divides the working modes of the three-phase-single-phase matrix converter into 12 types according to the current direction, peak current and three-phase voltage state. According to the flow direction of the resonant current, each cycle of the resonant current is divided into a positive half-cycle and a negative half-cycle. When the current passes through zero, it is determined whether the circuit needs energy injection based on the peak current signal and current direction collected in the previous half-cycle. If the absolute value of the peak current signal is less than the set current value and the current direction is negative, energy needs to be injected in the next positive half-cycle to enter the energy injection working mode. If the current direction is positive or the absolute value of the peak current signal is greater than the set current value, energy does not need to be injected, and the circuit oscillates freely. When entering the free oscillation working mode, the voltage input to the circuit each time is the maximum line voltage of the three-phase power supply at this time. Each working mode starts when the current passes through zero and continues until the next current passes through zero. High-frequency current output is achieved through combined modulation of switches.

2. The wireless power transmission system based on matrix converter according to claim 1, characterized in that: The transmitting device includes a primary transmitting coil and a primary compensation capacitor, and the receiving device includes a secondary receiving coil and a secondary compensation capacitor.

3. The wireless power transmission system based on matrix converter according to claim 1, characterized in that: A driving circuit is also provided between the DSP controller and the three-phase-single-phase matrix converter.

4. The wireless power transmission system based on matrix converter according to claim 1, characterized in that: The current acquisition module includes a current Hall sensor and a current signal acquisition circuit. The current signal acquisition circuit adopts a dual-channel comparator, channel one is used as a zero-crossing comparison circuit, and channel two is used for current amplitude detection.

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