Composite PWM controlled wireless power transmission system multi-parameter online identification system and method

Abstract

The present invention relates to the field of wireless power transmission technology, and specifically discloses a multi-parameter online identification system and method for a composite PWM controlled wireless power transmission system. The system includes a DC power supply, a high-frequency inverter, a primary energy transmitting module, a secondary energy receiving module, a system load, and a primary signal processing module; the primary signal processing module includes a current detection circuit, a DSP module, and a composite modulation wave SPWM control circuit; the DSP module controls the composite modulation wave control circuit to output a corresponding number of composite PWM modulation waves of different frequencies to drive the high-frequency inverter to work according to the number of parameters to be identified; and the system parameters are identified according to the collected current signal. The present invention can perform multi-parameter identification in real time by detecting the current input by the composite PWM control circuit to control the high-frequency inverter, thereby improving the dynamic performance of the system; multi-parameter dynamic identification can be performed only by detecting at the system transmitting end, without the need for additional communication devices, and with low hardware cost; flexible control and high identification accuracy.

Description

Technical Field

[0001] The present invention relates to the technical field of wireless power transmission, and in particular to a multi-parameter online identification system and method for a composite PWM controlled wireless power transmission system. Background Art

[0002] Traditional power transmission methods usually use cables and other connection devices to allow electrical equipment to obtain power from the power grid. The connection parts are exposed to the outside and will be damaged and sparked by friction, which will not only reduce the service life of electrical equipment, but also threaten the safety of power supply, especially in harsh environments such as mines and oil fields, and may even cause major safety accidents.

[0003] In response to the above problems, wireless power transmission came into being. Wireless power transmission technology, that is, the direct connection between the power grid and the power-consuming equipment without the need for cables or other connecting devices, has greatly solved the shortcomings of traditional power supply methods. Currently, the most studied wireless power transmission method is inductively coupled power transfer (ICPT) technology. As the research progresses, researchers have gradually paid attention to the parameter adaptability of the system. The mutual inductance and load parameters of the wireless power transmission system have variable and unknown characteristics. Changes in the mutual inductance and load parameters will cause the operating frequency of the system to drift, deviate from the resonant frequency of the system, and make the system stability worse, which in turn creates difficulties for the research of the ICPT system.

[0004] To solve this problem, the current methods are mostly based on the law of conservation of energy, and the energy formula of the primary and secondary sides is used to obtain the load parameter size. However, due to the invisibility of energy and the fact that this method ignores many factors, the load parameter value calculated by this method is not very accurate. For example, the document "Parameter Identification and Constant Current Control of Inductive Power Transmission System" measures the zero-crossing point of the waveform of the primary resonant voltage and current of the system, and measures the load parameter size of the system according to the equal energy stored in the system at the zero-crossing point. However, due to the problem of zero-crossing accuracy, the impedance measured by this method is not accurate; the document "Load Identification Algorithm of Non-Contact Power Transmission System" uses different system models to calculate the size of the load parameter according to the different properties of the load parameters, but this method does not measure the mutual inductance parameters of the primary and secondary sides. The coupling degree between the pickup core of the secondary circuit and the primary circuit guide coil, the equivalent resistance of the guide coil, and the changes in the resonant frequency of the system will affect the identification of the load parameters, so it has a certain impact on the identification accuracy of the load parameters. In addition, a common defect of the existing mutual inductance and load parameter identification algorithms of wireless power transmission systems is that power cannot be transmitted while parameter identification is in progress, that is, the two working states of parameter identification and power transmission cannot be performed simultaneously, and mutual inductance and load parameters cannot be dynamically identified. Summary of the invention

[0005] In view of the above-mentioned defects, the primary purpose of the present invention is to provide a system with high recognition accuracy, simple circuit structure, and capable of realizing dynamic parameter recognition of mutual inductance and load parameters under normal power supply mode. By directly and accurately measuring the primary current, the size of the mutual inductance and load parameters can be calculated, thereby realizing online recognition of the mutual inductance and load parameters of the wireless power transmission system.

[0006] To achieve the above purpose, the specific technical solutions adopted by the present invention are as follows:

[0007] A composite PWM controlled wireless power transmission system multi-parameter online identification system, the key of which is that it includes a DC power supply, a high-frequency inverter, a primary energy transmitting module, a secondary energy receiving module, a system load and a primary signal processing module;

[0008] The primary signal processing module includes a current detection circuit for connecting to the primary energy transmitting module and collecting the transmitting side current, a DSP module connected to the current detection circuit, and a composite modulation wave SPWM control circuit connected to the DSP module and used to drive the high frequency inverter;

[0009] The DSP module controls the composite modulation wave control circuit to output a corresponding number of composite PWM modulation waves of different frequencies to drive the high-frequency inverter to work according to the number of parameters that need to be identified; the DSP module identifies the system parameters according to the current signal collected by the current detection circuit, and controls the composite modulation wave control circuit in combination with the identified system parameters to change the output power of the high-frequency inverter.

[0010] Optionally, the primary energy transmission module uses a filter capacitor C p and the primary magnetic energy transmitting coil L p A series resonant circuit is formed.

[0011] Optionally, the secondary energy receiving module includes secondary magnetic energy pickup coils L connected in sequence. s and the secondary compensation capacitor C s .

[0012] Optionally, the primary energy transmitting module (3) and the secondary energy receiving module (4) resonate at the system operating frequency f0, and the filter capacitor C p and the primary magnetic energy transmitting coil L p Satisfaction between Secondary magnetic energy pickup coil L s and the secondary compensation capacitor C s Satisfaction between

[0013] Optionally, when the number of parameters to be identified is n, the composite modulation wave control circuit outputs n composite PWM modulation waves of different frequencies; one of them is used as an energy supply modulation wave, and its frequency is the system operating frequency f0; the remaining n-1 are used as identification modulation waves, and the high-frequency inverter (2) is controlled only in a transient state where parameter identification is required.

[0014] Optionally, the parameters to be identified include mutual inductance M; or / and the inductance and resistance of a single inductive load; or / and the capacitance and resistance of a single capacitive load; or / and the resistance of a pure resistive load.

[0015] Optionally, when performing parameter identification, the DSP module performs FFT analysis on the current signal collected by the current detection circuit, decomposes it to obtain the effective value of the current on the transmitting side at different frequencies, and constructs an equation relationship between voltage and current at different frequencies based on the parameters to be identified, thereby analyzing and obtaining the parameters to be identified.

[0016] Based on the above system, another object of the present invention is to provide a method for online identification of multiple parameters of a composite PWM controlled wireless power transmission system, comprising the following steps:

[0017] S1: The DSP module controls the composite modulation wave control circuit to output a corresponding number of composite PWM modulation waves of different frequencies to drive the high-frequency inverter to work according to the number of parameters to be identified, wherein one of the frequencies is the system operating frequency, so that the primary energy transmitting module and the secondary energy receiving module resonate at the system operating frequency, and the secondary magnetic energy pickup coil receives energy from the primary energy transmitting module and transmits it to the system load;

[0018] S2: The DSP module obtains the current signal in the primary energy transmission module through the current detection circuit, and obtains the effective value of the current at each frequency through fast Fourier transform FFT decomposition;

[0019] S3: Based on the parameters to be identified, the voltage and current equations at different frequencies are constructed, so as to derive the parameters to be identified through analysis;

[0020] S4: Changing the working state of the high-frequency inverter according to the identified parameters to adapt it to the current load demand.

[0021] Optionally, the system periodically enters a parameter identification state and executes steps S1-S4; in a non-parameter identification state, the composite modulation wave control circuit stops emitting a PWM modulation wave of a non-system operating frequency.

[0022] Optionally, the system sets the energy transfer state and parameter identification transient state. After the system is started, it first enters the parameter identification transient state and performs parameter identification according to steps S1-S4; then the composite modulation wave control circuit stops emitting PWM modulation waves of non-system operating frequencies, and the system enters the energy transfer state. The DSP module continues to detect current changes online according to the current detection circuit. When the current change exceeds a preset threshold, the system re-enters the parameter identification transient state.

[0023] The remarkable effects of the present invention are:

[0024] Compared with the traditional parameter identification method of wireless power transmission system, the present invention solves the problems of inaccuracy of the traditional method, complex circuit and difficult detection, and can control the composite modulation wave control circuit to output the corresponding number of composite PWM modulation waves of different frequencies to drive the high-frequency inverter to work according to the number of parameters to be identified without cutting off the main circuit, and directly identify the size of the mutual inductance parameter between the primary and secondary sides of the system and the nature and size of the load parameter by detecting the primary current, that is, realize multi-parameter identification and power transmission at the same time; and the frequency and power of the present invention are convenient to adjust, and can be adjusted according to the needs to meet the needs of the load; at the same time, because the high-frequency inverter outputs voltage by the composite PWM control method, harmonics are easily eliminated, and the parameter identification accuracy is improved. The system adopts the composite modulation PWM control method to identify mutual inductance and load parameters, and its steps are simple, and the recognition accuracy of mutual inductance and load parameters is high. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a schematic diagram of the system circuit structure of the present invention;

[0026] Figure 2 is the inverter output voltage waveform diagram of the present invention;

[0027] Figure 3 This is a current waveform diagram of the primary energy transmitting module of the present invention;

[0028] Figure 4 This is a FFT analysis diagram of the primary energy transmission module current under certain mutual inductance and load parameters of the present invention;

[0029] Figure 5 It is a comparison table of mutual inductance and load parameter identification effects in a specific embodiment of the present invention (a comparison table of given mutual inductance and load and identification results).

[0030] Labels in the figure: 1-DC power supply; 2-high frequency inverter; 3-primary energy transmitting module; 4-secondary energy receiving module; 5-system load; 6-primary signal processing module. DETAILED DESCRIPTION

[0031] The following specifically illustrates the implementation mode of the present invention in conjunction with the accompanying drawings. The embodiments are provided for illustrative purposes only and cannot be understood as limiting the present invention. The accompanying drawings are provided for reference and illustration only and do not constitute a limitation on the scope of patent protection of the present invention, because many changes can be made to the present invention without departing from the spirit and scope of the present invention.

[0032] like Figure 1 As shown, this embodiment provides a multi-parameter online identification system for a composite PWM controlled wireless power transmission system, comprising a DC power supply 1, a high-frequency inverter 2, a primary energy transmitting module 3, a secondary energy receiving module 4, a system load 5 and a primary signal processing module 6;

[0033] In the specific implementation, the high-frequency inverter 2 adopts a full-bridge inverter circuit to obtain a larger power output; the DC signal output by the DC power supply 1 enters the primary energy transmission module 3 after high-frequency inversion by the high-frequency inverter 2; taking the wireless power transmission system with a system operating frequency of 20kHz as an example, the primary energy transmission module 3 adopts a filter capacitor C p and the primary magnetic energy transmitting coil L p The secondary energy receiving module 4 comprises a secondary magnetic energy pickup coil L connected in sequence. s And the secondary compensation capacitor C s , where the primary magnetic energy transmitting coil L p The inductance is 291μH, and the filter capacitor C p The capacitance value is 0.2176μF, and the secondary magnetic energy pickup coil L s The inductance is 291μH, and the secondary compensation capacitor C s The capacitance value is 0.2176μF, and the voltage value of the DC power supply 1 is 24V. This causes the primary energy transmitting module 3 and the secondary energy receiving module 4 to resonate at the system operating frequency f0, and the filter capacitor C p and the primary magnetic energy transmitting coil L p Satisfaction between Secondary magnetic energy pickup coil L s And the secondary compensation capacitor C s Satisfaction between

[0034] The primary signal processing module 6 includes a current detection circuit for connecting to the primary energy transmitting module 3 and collecting the transmitting side current, a DSP module connected to the current detection circuit, and a composite modulation wave SPWM control circuit connected to the DSP module and used to drive the high-frequency inverter 2;

[0035] The DSP module controls the composite modulation wave control circuit to output a corresponding number of composite PWM modulation waves of different frequencies to drive the high-frequency inverter 2 to work according to the number of parameters that need to be identified; the DSP module identifies the system parameters according to the current signal collected by the current detection circuit, and controls the composite modulation wave control circuit in combination with the identified system parameters to change the output power of the high-frequency inverter 2, specifically, the operating frequency and duty cycle of the high-frequency inverter 2 can be changed to achieve output power control and voltage regulation of the high-frequency inverter 2.

[0036] In specific implementation, when the number of parameters that need to be identified is n, the composite modulation wave control circuit outputs n composite PWM modulation waves of different frequencies; one of them is used as an energy supply modulation wave, and its frequency is the system operating frequency f0; the remaining n-1 are used as identification modulation waves, and the high-frequency inverter 2 is controlled only in the transient state where parameter identification is required.

[0037] The following takes the identification of three parameters of mutual inductance and a single inductive load (M, R, L) as an example to further introduce the multi-parameter online identification method of the composite PWM controlled wireless power transmission system provided by the present invention, which specifically includes the following steps:

[0038] S1: The DSP module controls the composite modulation wave control circuit to output a corresponding number of composite PWM modulation waves of different frequencies according to the number of parameters to be identified to drive the high-frequency inverter 2 to work, wherein one of the frequencies is the system operating frequency, so that the primary magnetic energy transmitting coil in the primary energy transmitting module 3 and the secondary magnetic energy picking-up coil in the secondary energy receiving module 4 are coupled, and the secondary magnetic energy picking-up coil receives the energy from the primary energy transmitting module and transmits it to the system load 5;

[0039] In this example, three parameters need to be identified, M is the mutual inductance coefficient, R is the resistance value of a single inductive load, and L is the inductance value of a single inductive load; the primary signal processing module controls the high-frequency inverter to output electric energy of three different frequencies f0, f1 and f2, one of which is the frequency of energy transmission of the system, and the other two frequencies f1 and f2 are the frequencies when the system performs parameter identification;

[0040] S2: The DSP module obtains the current signal in the primary energy transmitting module 3 through the current detection circuit, and obtains the effective value of the current at each frequency through fast Fourier transform FFT decomposition;

[0041] At this time, through analysis, we can get the current value I at the energy transfer frequency f0 in the primary current of the system. p0 , the current value I at the modulation wave frequency f1 p1 And the current value I under the modulation wave frequency f2 p2 ;

[0042] S3: Based on the parameters to be identified, the voltage and current equations at different frequencies are constructed, so as to derive the parameters to be identified through analysis;

[0043] From the superposition theorem, we know that the current I of the three frequencies f0, f1, and f2 decomposed from the primary energy transmission module of the system is p0 ,I p1 ,I p2 , which can be regarded as the current I p0 ,I p1 ,I p2 The superposition theorem is used to establish a group of equations about mutual inductance parameters and resistance parameters. Taking the inductive load as an example, the established group of equations is:

[0044]

[0045]

[0046]

[0047] According to this set of equations, the system mutual inductance parameter M and the system load resistance R and inductance L can be obtained; where U0, U1, and U2 are the current I p0 ,I p1 ,I p2 The voltage effective value of the high-frequency inverter 2 when acting alone, ω0, ω1 and ω2 are the current I p0 ,I p1 ,I p2 The operating frequency of the system when acting alone;

[0048] S4: Changing the working state of the high-frequency inverter (2) according to the identified parameters to adapt it to the current load demand.

[0049] After the secondary impedance is refracted to the primary side, in the resonant state, the total impedance of the primary side is:

[0050]

[0051] In the non-resonant state, the total impedance of the primary side is:

[0052]

[0053]

[0054] Combined with the above process, when the system sets a mutual inductance and load (such as mutual inductance M = 171μH, load R = 100Ω, L = 100μH), according to the above data, the primary voltage can be obtained as:

[0055] U0=U1=U2=0.3U d=0.3×24=7.2V

[0056] The system operating frequency is:

[0057] ω0=2πf0=2π×20000=40000πHz

[0058] When the system performs mutual inductance and load parameter detection, two other frequency energies are added, namely 40kHz and 60kHz, and the angular frequency is calculated as:

[0059] ω1=2πf1=2π×40000=80000πHz

[0060] ω2=2πf2=2π×60000=120000πHz

[0061] Combined with the calculation formula analyzed above, we have:

[0062]

[0063]

[0064]

[0065] Among them, I p0 ,I p1 and I p2 Obtained from the FTT analysis results of the primary current.

[0066] Calculated by the formula:

[0067]

[0068] The error is:

[0069]

[0070] The errors of the calculated mutual inductance and load parameters are within the engineering error of 5%, that is, the system and method proposed by the present invention can realize the mutual inductance and load parameter identification method of the wireless power transmission system; Figure 2 is the inverter output voltage of the present invention, Figure 3 The current waveform of the primary energy transmission module rail of the present invention is: Figure 4 This is an FFT analysis diagram of the primary energy transmission module current under certain mutual inductance and load parameters of the present invention.

[0071] In addition, multiple experiments were conducted by replacing different loads, and the statistical results are as follows: Figure 5 As described above, it can be seen that the identification errors of the system parameters are all within an acceptable range, which fully verifies the feasibility of the present invention.

[0072] In addition to parameter identification for a single inductive load, the system can also realize parameter identification for a single capacitive load, a single pure resistive load, or even when multiple loads are connected to the system.

[0073] In specific implementation, the system can periodically enter the parameter identification state and execute steps S1-S4; in the non-parameter identification state, the composite modulation wave control circuit stops emitting PWM modulation waves of non-system operating frequencies. As another implementation method, the system also sets the energy transfer state and parameter identification transient state. After the system is started, it first enters the parameter identification transient state and performs parameter identification according to steps S1-S4; then the composite modulation wave control circuit stops emitting PWM modulation waves of non-system operating frequencies, the system enters the energy transfer state, and the DSP module continues to detect current changes online according to the current detection circuit. When the current change exceeds the preset threshold, the system re-enters the parameter identification transient state.

[0074] In summary, it can be seen that the composite PWM controlled wireless power transmission system multi-parameter online identification system and method provided by the present invention can perform multi-parameter identification in real time by detecting the size of the system input current, thereby improving the dynamic performance of the system; multi-parameter dynamic identification can be performed only by detection at the system transmitting end, without the need for additional communication devices, and with low hardware costs; the control is flexible and the identification accuracy is high.

[0075] Finally, it should be noted that the above embodiments are preferred implementations of the present invention, but the implementations of the present invention are not limited to the above embodiments, and any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be equivalent replacement methods and are included in the protection scope of the present invention.

Claims

1. A multi-parameter online identification system for composite PWM controlled wireless power transmission system, It is characterized in that It comprises a direct current power supply (1), a high-frequency inverter (2), a primary energy transmitting module (3), a secondary energy receiving module (4), a system load (5) and a primary signal processing module (6); The primary signal processing module (6) comprises a current detection circuit for connecting to the primary energy transmitting module (3) and collecting transmitting side current, a DSP module connected to the current detection circuit, and a composite modulation wave SPWM control circuit connected to the DSP module and used to drive the high frequency inverter (2); The DSP module controls the composite modulation wave control circuit to output a corresponding number of composite PWM modulation waves of different frequencies to drive the high-frequency inverter (2) to work according to the number of parameters to be identified; the DSP module identifies the system parameters according to the current signal collected by the current detection circuit, and controls the composite modulation wave control circuit in combination with the identified system parameters to change the output power of the high-frequency inverter (2); When the number of parameters to be identified is n, the composite modulation wave control circuit outputs n composite PWM modulation waves of different frequencies; one of them is used as the power supply modulation wave, and its frequency is the system operating frequency f 0 The remaining n-1 are used as identification modulation waves, and the high frequency inverter (2) is controlled only in the transient state where parameter identification is required; When performing parameter identification, the DSP module performs FFT analysis on the current signal collected by the current detection circuit, decomposes it to obtain the effective value of the current on the transmitting side at different frequencies, and constructs the voltage and current equation relationship at different frequencies based on the parameters to be identified, thereby analyzing and obtaining the parameters to be identified.

2. According to claim 1, the multi-parameter online identification system of the composite PWM controlled wireless power transmission system, It is characterized in that The primary energy transmitting module (3) adopts a filter capacitor C p and the primary magnetic energy transmitting coil L p A series resonant circuit is formed.

3. The multi-parameter online identification system of the composite PWM controlled wireless power transmission system according to claim 2, It is characterized in that The secondary energy receiving module (4) comprises secondary magnetic energy pickup coils L connected in sequence s and the secondary compensation capacitor C s .

4. The multi-parameter online identification system of the composite PWM controlled wireless power transmission system according to claim 3, It is characterized in that The primary energy transmitting module (3) and the secondary energy receiving module (4) are connected at a system operating frequency f 0 Resonance occurs under the filter capacitor C p and the primary magnetic energy transmitting coil L p Satisfaction between Secondary magnetic energy pickup coil L s and the secondary compensation capacitor C s Satisfaction between 5. The multi-parameter online identification system of the composite PWM controlled wireless power transmission system according to claim 1, It is characterized in that The parameters to be identified include the mutual inductance coefficient M; or / and the inductance value and resistance value of a single inductive load; or / and the capacitance value and resistance value of a single capacitive load; or / and the resistance value of a purely resistive load.

6. A method for online identification of multiple parameters of a composite PWM controlled wireless power transmission system, using the composite PWM controlled wireless power transmission system online identification of multiple parameters as claimed in any one of claims 1 to 5, It is characterized in that The following steps are involved: S1: The DSP module controls the composite modulation wave control circuit to output a corresponding number of composite PWM modulation waves of different frequencies to drive the high-frequency inverter (2) to work according to the number of parameters to be identified, wherein one of the frequencies is the system operating frequency, so that the primary energy transmitting module (3) and the secondary energy receiving module (4) resonate at the system operating frequency, and the secondary magnetic energy pickup coil receives energy from the primary energy transmitting module and transmits it to the system load (5); S2: The DSP module obtains the current signal in the primary energy transmission module (3) through the current detection circuit, and obtains the effective value of the current at each frequency through fast Fourier transform FFT decomposition; S3: Based on the parameters to be identified, the voltage and current equations at different frequencies are constructed, so as to derive the parameters to be identified through analysis; S4: Changing the working state of the high-frequency inverter (2) according to the identified parameters to adapt it to the current load demand.

7. The multi-parameter online identification method of the composite PWM controlled wireless power transmission system according to claim 6, It is characterized in that The system periodically enters the parameter identification state and executes steps S1-S4; in the non-parameter identification state, the composite modulation wave control circuit stops emitting a PWM modulation wave of a non-system operating frequency.

8. The multi-parameter online identification method of the composite PWM controlled wireless power transmission system according to claim 6, Features: The system sets the energy transfer state and parameter identification transient state. After the system is started, it first enters the parameter identification transient state and performs parameter identification according to steps S1-S4. Then the composite modulation wave control circuit stops emitting PWM modulation waves of non-system operating frequencies, and the system enters the energy transfer state. The DSP module continues to detect current changes online according to the current detection circuit. When the current change exceeds the preset threshold, the system re-enters the parameter identification transient state.

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