CN211236016U - Frequency online detection circuit for constant voltage or constant current output in wireless power transmission - Google Patents
Frequency online detection circuit for constant voltage or constant current output in wireless power transmission Download PDFInfo
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Abstract
The utility model relates to a frequency on-line detection circuit of wireless power transmission constant voltage or constant current output, including the magnetic coupling system, be equipped with DC voltage source, full-bridge inverter circuit, former side compensation capacitance at the transmitting side of magnetic coupling system, be equipped with loads such as vice side compensation capacitance, rectifier circuit, filter circuit and lithium cell group etc. at the receiving side of magnetic coupling system; the PWM driving circuit also comprises a control module, a PWM driving circuit and a current detection circuit. By capturing the current frequency of the transmitting coil, the resonant frequency of the transmitting side can be detected online.
Description
Technical Field
The utility model relates to a non-contact charging system technical field, especially an online detection circuitry of frequency of wireless power transmission constant voltage or constant current output.
Background
With the rapid development of the electric automobile industry, people put higher demands on the safety and convenience of a charging system. Therefore, the contactless charging system for the electric vehicle is also increasingly widely used. The vehicle can be charged quickly without connecting the vehicle with a power supply by using a cable, and the charging service can be provided for various electric vehicles in various occasions such as parking lots, houses, roads and the like, so that the charging at any time and any place becomes possible.
Currently, wireless (non-contact) charging of an automobile mainly includes three types, namely electromagnetic induction, magnetic field resonance, and microwave type, wherein magnetic resonance type charging has advantages in terms of charging distance and efficiency. The technology is that a transmitting coil and a receiving coil are adjusted into a resonance system, and when the oscillation frequency and the natural frequency of a transmitting end are the same, the two coils generate resonance at the same time, so that the energy transmission with the maximum efficiency is realized.
However, when the inductance of the coil and the capacitance of the compensation capacitor are changed by factors such as a transmission distance and heat generation in the transmitting and receiving coils, the resonance frequency is changed, and the transmission efficiency is rapidly lowered. Therefore, a control circuit is required to adjust the oscillation frequency of the transmitting coil, so that the coils of the primary unit and the secondary unit work in a certain working state, and the system obtains better output performance.
In the prior art, a real-time frequency tracking circuit based on a phase-locked loop exists, and the tuning method utilizes the characteristic of closed-loop feedback control of the phase-locked loop and controls the frequency of a PWM controller to output a driving signal according to the frequency of current output by a transmitting end, so that the working frequency of the transmitting end of a system is always the same as the resonant frequency. The resonance state is detected at the side of the transmitting coil, even if the inherent resonance frequencies of the transmitting coil and the receiving coil are inconsistent, the whole coil system consisting of the transmitting coil and the receiving coil can resonate in a frequency adjusting mode, the influence caused by the inconsistency of the inherent resonance frequencies of the coils is reduced, and the larger output power can be ensured. However, the frequency tracking tuning method based on the phase-locked loop cannot ensure that the transmitting coil and the receiving coil are both in a resonance state, and the transmission performance of the system cannot be optimal. The output voltage or current cannot be guaranteed to be constant when the load resistance changes. In many power electronic applications, a constant voltage or constant current characteristic is required, so that the phase-locked loop technology cannot meet the current requirements.
Disclosure of Invention
In view of this, the utility model aims at providing a frequency on-line measuring circuit of wireless power transmission constant voltage or constant current output, through the utility model discloses a circuit can detect the electric current of transmitting side coil, detects and realizes providing the hardware circuit to the accurate regulation of the oscillation frequency of transmitting terminal for subsequent current frequency.
The utility model discloses a following scheme realizes: a wireless power transmission constant voltage output frequency online detection circuit with SP and PP compensation structures comprises a magnetic coupling system, wherein a direct current voltage source, a full-bridge inverter circuit and a primary side compensation capacitor C are arranged on the transmitting side of the magnetic coupling systempA secondary compensation capacitor C is arranged on the receiving side of the magnetic coupling systemmThe lithium battery pack comprises a rectifier circuit, a filter circuit and a load comprising the lithium battery pack; the device also comprises a primary side control module, a primary side PWM driving circuit, a current detection circuit, a secondary side control module and a secondary side PWM driving circuit;
two ends of the direct current voltage source are respectively connected with two input ends of the full-bridge inverter circuit, and one output end of the full-bridge inverter circuit passes through the primary side compensation capacitor CpThe other output end of the full-bridge inverter circuit is connected to the other end of the transmitting side of the magnetic coupling system; receiving side of magnetic coupling system and secondary side compensation capacitor CmThe output ends of the rectifying circuits are connected to loads including the lithium battery pack through the filter circuit;
the input end of the current detection circuit is connected to the transmitting side of the magnetic coupling system, the output end of the current detection circuit is connected to the primary side control module, the primary side control module is connected to the full-bridge inverter circuit through the PWM driving circuit and used for controlling the work of a switching tube in the full-bridge inverter circuit, the secondary side control module is in communication connection with the primary side control module, and the secondary side control module is connected to the rectifying circuit through the secondary side PWM driving circuit and used for controlling the work of the switching tube in the rectifying circuit.
The current detection circuit comprises a Hall sensor or a current transformer, a zero-crossing comparison circuit and a voltage division circuit which are sequentially connected, wherein the Hall sensor or the current transformer is used for detecting the current of the transmitting side of the magnetic coupling system, and the output of the voltage division circuit is connected to the primary side control module. The control module adopts a DSP or a singlechip.
Based on the frequency online detection circuit for constant voltage output in wireless power transmission, the following detection method can be realized, and specifically: by obtaining the primary compensation capacitance C in real timepPrimary side equivalent leakage inductance L of magnetic coupling systempkThe resonant frequency of the full-bridge inverter circuit is equal to the resonant frequency, and constant voltage output is realized.
Wherein the real-time acquisition of the primary compensation capacitance CpPrimary side equivalent leakage inductance L of magnetic coupling systempkThe resonant frequency of (2) specifically comprises the steps of:
step S1: the primary side control module is communicated with the secondary side control module, the secondary side control module applies PWM signals to a switching tube in the rectifying circuit through a secondary side PWM driving circuit, and the switching tube S5 and the switching tube S7 in the rectifying circuit are closed or the switching tube S6 and the switching tube S8 are closed to enable the receiving side of the magnetic coupling system to be short-circuited; the S5, the S6, the S7 and the S8 are switching tubes in the rectifying circuit, one end of the S5 is connected with one end of the S7, one end of the S6 is connected with one end of the S8 and respectively used as two output ends of the rectifying circuit, the other end of the S5 is connected with the other end of the S6, and the other end of the S7 is connected with the other end of the S8 and respectively used as two input ends of the rectifying circuit;
step S2: the primary side control module applies PWM signals to the switching tube in the full-bridge inverter circuit through the primary side PWM driving circuit, and closes the switching tube S1 and the switching tube S4 or opens and closesThe switch tube S2 and the switch tube S3 apply the input DC voltage source to the compensation capacitor CpAnd a magnetic coupling system; the S1, the S2, the S3 and the S4 are switching tubes in a full-bridge inverter circuit, one end of the S1 is connected with one end of the S3, one end of the S2 is connected with one end of the S4 and respectively used as two input ends of the full-bridge inverter circuit, the other end of the S1 is connected with the other end of the S2, and the other end of the S3 is connected with the other end of the S4 and used as two output ends of the full-bridge inverter circuit;
step S3: detecting the transmission side of the magnetic coupling system via the primary side compensation capacitor CpCurrent of (I)LFrequency of (I) ofLHas a frequency of CpAnd LpkThe resonant frequency of (c).
Further, in step S3, specifically, a hall sensor or a current transformer is used to detect the current I flowing through the primary side compensation capacitorLThen converting the voltage signal into a voltage signal with amplitude changing from zero up to zero, then entering a zero-crossing comparison circuit, outputting high level at the moment of positive voltage, and outputting zero at the moment of negative voltage to obtain a square wave pulse signal with the same frequency and phase as the sine wave; the level output by the zero-crossing comparison circuit meets the input voltage range of the primary side control module through the voltage division circuit, and finally the signal enters the CAP capture unit of the control module to obtain the count value of a period waveform, calculate the time of the period, and convert the period into the resonant frequency.
The utility model also provides an online detection circuitry of frequency of wireless power transmission constant current output with SS and PS compensation structure, including the magnetic coupling system, be equipped with DC voltage source, full-bridge inverter circuit, former limit compensation capacitor C in the transmitting side of magnetic coupling systempA secondary compensation capacitor C is arranged on the receiving side of the magnetic coupling systemsThe power supply comprises a rectifying circuit, a switching tube S5, a filter circuit and a load including a lithium battery pack; the device also comprises a primary side control module, a primary side PWM driving circuit, a current detection circuit, a secondary side control module and a secondary side PWM driving circuit;
two ends of the direct current voltage source are respectively connected with two input ends of the full-bridge inverter circuit, and one output end of the full-bridge inverter circuit passes through the primary side compensation capacitor CpIs connected toThe other output end of the full-bridge inverter circuit is connected to the other end of the transmitting side of the magnetic coupling system; one end of the receiving side of the magnetic coupling system is compensated by the secondary side compensation capacitor CsThe switch tube S5 is connected to one input end of the rectifying circuit, the other end of the receiving side of the magnetic coupling system is connected to the other input end of the rectifying circuit, and the output end of the rectifying circuit is connected to a load including a lithium battery pack through a filter circuit;
the input end of the current detection circuit is connected to the transmitting side of the magnetic coupling system, the output end of the current detection circuit is connected to the primary side control module, the primary side control module is connected to the full-bridge inverter circuit through the primary side PWM driving circuit and used for controlling the work of a switch tube in the full-bridge inverter circuit, the primary side control module is in communication connection with the secondary side control module, and the secondary side control module is connected to the switch tube in the rectifying circuit and the switch tube S5 through the secondary side PWM driving circuit and used for controlling the work of the switch tube in the rectifying circuit and the work of the switch tube S5.
The current detection circuit comprises a Hall sensor or a current transformer, a zero-crossing comparison circuit and a voltage division circuit which are sequentially connected, wherein the Hall sensor or the current transformer is used for detecting the current of the transmitting side of the magnetic coupling system, and the output of the voltage division circuit is connected to the primary side control module. The control module adopts a DSP or a singlechip.
Based on the online detection circuitry of frequency of foretell wireless power transmission constant current output, the utility model discloses can realize following detection method, specifically do: by obtaining the primary compensation capacitance C in real timepSelf-inductance L of primary coil of magnetic coupling systempThe working frequency of the full-bridge inverter circuit is equal to the resonant frequency, and constant current output is realized.
Wherein the real-time acquisition of the primary compensation capacitance CpSelf-inductance L of primary coil of magnetic coupling systempThe resonant frequency of (a) specifically comprises the steps of:
step S1: the primary side control module is communicated with the secondary side control module, the secondary side control module applies PWM to a driving circuit of a switch tube S5, and the switch tube S5 is disconnected, so that the receiving side of the magnetic coupling system is opened;
step S2: the primary side control module applies PWM to a switching tube in the full-bridge inverter circuit through a primary side PWM driving circuit, and S1 and S4 or S2 and S3 are closed, so that a direct-current voltage source is applied to a compensation capacitor and a magnetic coupling system; wherein, S1, S2, S3 and S4 are switching tubes in the full-bridge inverter circuit, one end of S1 is connected with one end of S3, one end of S2 is connected with one end of S4 and respectively used as two input ends of the full-bridge inverter circuit, the other end of S1 is connected with the other end of S2, and the other end of S3 is connected with the other end of S4 and respectively used as two output ends of the full-bridge inverter circuit;
step S3: detecting the transmission side of the magnetic coupling system via the primary side compensation capacitor CpCurrent of (I)LDetecting ILFrequency of (I) ofLHas a frequency of CpAnd LpThe resonant frequency of (c).
Further, in step S3, a hall sensor or a current transformer is specifically used to detect the current I flowing through the primary side compensation capacitorLThen converting the voltage signal into a voltage signal with amplitude changing from zero up to zero, then entering a zero-crossing comparison circuit, outputting high level at the moment of positive voltage, and outputting zero at the moment of negative voltage to obtain a square wave pulse signal with the same frequency and phase as the sine wave; the level output by the zero-crossing comparison circuit meets the input voltage range of the primary side control module through the voltage division circuit, and finally the signal enters the CAP capture unit of the control module to obtain the count value of a period waveform, calculate the time of the period, and convert the period into the resonant frequency.
Compared with the prior art, the utility model discloses following beneficial effect has: through the utility model discloses a circuit can detect the electric current of transmitting side coil, detects and realizes providing the hardware circuit to the accurate regulation of the oscillation frequency of transmitting terminal for subsequent current frequency.
Drawings
Fig. 1 is an equivalent model of a magnetic coupling system according to an embodiment of the present invention, in which (a) is a coupling mutual inductance model and (b) is a transformer leakage inductance model.
Fig. 2 is an SP type leakage inductance compensation equivalent model according to an embodiment of the present invention.
Fig. 3 is the PP-type leakage inductance compensation equivalent model according to the embodiment of the present invention.
Fig. 4 is the PP-type leakage inductance compensation equivalent transformation model according to the embodiment of the present invention.
Fig. 5 is an SS type compensation topology according to an embodiment of the present invention.
Fig. 6 is a PS-type compensation topology according to an embodiment of the present invention.
Fig. 7 is a PS-type equivalent transformation compensation topology according to an embodiment of the present invention.
Fig. 8 is an embodiment of the present invention, which is an on-line detection circuit for constant voltage output frequency of wireless power transmission with SP and PP compensation structures.
Fig. 9 is a primary equivalent circuit (SP compensation structure) of the constant voltage output type transmission side according to the embodiment of the present invention.
Fig. 10 is a primary equivalent circuit (PP compensation structure) of the constant voltage output type of the present invention.
Fig. 11 is an on-line detection circuit of the wireless power transmission constant current output frequency with SS and PS compensation structures according to an embodiment of the present invention.
Fig. 12 is a constant current output type transmission side primary side equivalent circuit (SS compensation structure) according to an embodiment of the present invention.
Fig. 13 is a constant current output type transmitting side primary side equivalent circuit (PS compensation structure) according to an embodiment of the present invention.
Fig. 14 is a zero-cross comparison circuit according to an embodiment of the present invention.
Fig. 15 is a voltage divider circuit according to an embodiment of the present invention.
Detailed Description
The present invention will be further explained with reference to the drawings and the embodiments.
As shown in fig. 1, the magnetic coupling system of the wireless power transmission system generally consists of two coils, and can be described by a coupling mutual inductance model (fig. 1 (a)) and a transformer leakage inductance model (fig. 1 (b)). The coupling mutual inductance model has 3 parameters, and the transformer leakage inductance model has 4 parameters, so that respective impedance parameter equations of the two are obtained through a two-port network theory. According to impedance parametersThe matrixes are equal, and the characteristic that the parameter of the magnetic coupling system under the transformer leakage inductance model has a formula I, namely the primary equivalent leakage inductance LpkD, exciting inductance LmSecondary equivalent leakage inductance LskAs a function of the voltage conversion ratio n.
In order to establish a resonant topology for obtaining a constant voltage type output, a leakage inductance compensation mode is adopted. The magnetic coupling system is equivalent to a transformer leakage inductance model, and the current secondary side voltage conversion ratio n is equal to L according to a formula (I)sIn the case of/M, the inductive parameters in the leakage inductance model are as follows:
because the secondary equivalent leakage inductance does not exist, the series compensation capacitor is not needed, and the parallel compensation capacitor C is adoptedmSame as LmResonance, reduction of LmThe reactive energy consumed; resonant capacitor C added to primary sidepThe equivalent leakage inductance L of the same primary side of the capacitorpkAnd resonance and parameter design according to the formula (III). A serial/parallel compensation network can thus be constructed as shown in fig. 2. Load RoThe two ends are equivalent to an applied voltage source, so that the system has the characteristic of constant output voltage.
And for the inverter with current source type input end, the equivalent current source IinAs shown in fig. 3. Using Thevenin theorem to connect current source IinAnd a capacitor CpThe parallel circuit is equivalent to a voltage source
And a capacitor CpSeries configuration, as shown in FIG. 4, using the principle of leakage inductance compensationpAnd LpkResonance, CmAnd LmResonate, thereforeA and/or compensation network is formed. Load ReTwo ends are equivalent to an applied voltage source
The system has the characteristic of constant voltage output.
It can be seen that C in the SP and PP structurespAnd LpkThe resonance effect is to make the circuit realize constant voltage output, and CmAnd LmThe effect of the resonance is to reduce the reactive component of the circuit and thereby increase the overall efficiency of the system. Therefore, as long as C can be ensuredpAnd LpkAnd the system can realize constant voltage output by resonance. The traditional phase-locked loop control technology cannot guarantee CpAnd LpkAnd resonates, and thus a constant voltage output characteristic cannot be obtained.
Therefore, as shown in fig. 8, the present embodiment provides an on-line frequency detection circuit with SP and PP compensation structures for constant voltage output in wireless power transmission, which includes a magnetic coupling system, and a dc voltage source, a full-bridge inverter circuit, and a primary compensation capacitor C are disposed on a transmitting side of the magnetic coupling systempA secondary compensation capacitor C is arranged on the receiving side of the magnetic coupling systemmThe lithium battery pack comprises a rectifier circuit, a filter circuit and a load comprising the lithium battery pack; the device also comprises a primary side control module, a primary side PWM driving circuit, a current detection circuit, a secondary side control module and a secondary side PWM driving circuit;
two ends of the direct current voltage source are respectively connected with two input ends of the full-bridge inverter circuit, and one output end of the full-bridge inverter circuit passes through the primary side compensation capacitor CpThe other output end of the full-bridge inverter circuit is connected to the other end of the transmitting side of the magnetic coupling system; receiving side of magnetic coupling system and secondary side compensation capacitor CmThe output ends of the rectifying circuits are connected to loads including the lithium battery pack through the filter circuit;
the input end of the current detection circuit is connected to the transmitting side of the magnetic coupling system, the output end of the current detection circuit is connected to the primary side control module, the primary side control module is connected to the full-bridge inverter circuit through the PWM driving circuit and used for controlling the work of a switching tube in the full-bridge inverter circuit, the secondary side control module is in communication connection with the primary side control module, and the secondary side control module is connected to the rectifying circuit through the secondary side PWM driving circuit and used for controlling the work of the switching tube in the rectifying circuit.
In this embodiment, the current detection circuit includes a hall sensor or a current transformer, a zero-crossing comparison circuit, and a voltage division circuit, which are connected in sequence, where the hall sensor or the current transformer is used to detect the current at the transmitting side of the magnetic coupling system, and the output of the voltage division circuit is connected to the primary side control module.
In this embodiment, the detection method of the frequency online detection circuit based on the wireless power transmission constant voltage output specifically includes: by obtaining the primary compensation capacitance C in real timepPrimary side equivalent leakage inductance L of magnetic coupling systempkThe resonant frequency of the full-bridge inverter circuit is equal to the resonant frequency, and constant voltage output is realized.
Wherein the real-time acquisition of the primary compensation capacitance CpPrimary side equivalent leakage inductance L of magnetic coupling systempkThe resonant frequency of (2) specifically comprises the steps of:
step S1: after the primary side control module and the secondary side control module are successfully communicated, the secondary side control module controls the state of a switching tube in the rectifying circuit to enable the receiving side of the magnetic coupling system to be short-circuited; specifically, a drive circuit for controlling the secondary-side switching tubes S5, S7, S6, and S8 applies a pulse to turn on S5, S7, S6, and S8; the S5, the S6, the S7 and the S8 are switching tubes in the rectifying circuit, one end of the S5 is connected with one end of the S7, one end of the S6 is connected with one end of the S8 and respectively used as two output ends of the rectifying circuit, the other end of the S5 is connected with the other end of the S6, and the other end of the S7 is connected with the other end of the S8 and respectively used as two input ends of the rectifying circuit;
step S2: after the secondary side switch tube is finished, the drive circuit of the primary side switch tube S1, S4 or S2, S3 is controlled to apply a certain drive level, so that the switch tube S1, S4 or S2, S3 is conducted, and the input direct current voltage source is applied to the compensation capacitor CpAnd a magnetic coupling system; at this time, the secondary side is short-circuited to excite the magnetFeeling LmThe voltage across is zero and is therefore also short-circuited; the S1, the S2, the S3 and the S4 are switching tubes in a full-bridge inverter circuit, one end of the S1 is connected with one end of the S3, one end of the S2 is connected with one end of the S4 and respectively used as two input ends of the full-bridge inverter circuit, the other end of the S1 is connected with the other end of the S2, and the other end of the S3 is connected with the other end of the S4 and used as two output ends of the full-bridge inverter circuit;
wherein, the constant voltage output type transmitting side primary side equivalent circuit SP compensation structure and PP compensation structure are respectively shown in fig. 9 and fig. 10;
step S3: detecting current I of transmitting side of magnetic coupling system through primary side compensation capacitorLDetecting ILFrequency of (I) ofLHas a frequency of CpAnd LpkThe resonant frequency of (c). Since the winding resistance r in an actual circuit is not negligible, the resulting circuit is an RLC second order circuit. Current I flowing through the circuitLThe waveform is a sine wave with attenuated amplitude and constant period, but the period is approximately equal to the resonance period of the LC loop due to the smaller value of r. Can obtain I by detectionLIs C, the frequency ispAnd LpkIs also the inverter operating frequency that needs to be employed.
In this embodiment, step S3 is to use a hall sensor or a current transformer to detect the current I flowing through the primary compensation capacitorLThen converting the voltage signal into a voltage signal with amplitude changing from zero up to zero, then entering a zero-crossing comparison circuit, outputting high level at the moment of positive voltage, and outputting zero at the moment of negative voltage to obtain a square wave pulse signal with the same frequency and phase as the sine wave; the level output by the zero-crossing comparison circuit meets the input voltage range of the primary side control module through the voltage division circuit, and finally the signal enters the CAP capture unit of the control module to obtain the count value of a period waveform, calculate the time of the period, and convert the period into the resonant frequency. Therefore, the DSP or the singlechip sends PWM waves with the same frequency as the resonant frequency to a switching tube driving circuit at the transmitting side, and the switching tube works under the oscillation frequency the same as the natural frequency, so that the purpose of frequency tracking is realized. In addition, the DSP is selected as the main controller,the functions of signal capture, digital processing, PWM pulse transmission and the like are mainly realized; the signal processing circuit consists of a voltage division circuit and a zero-crossing comparison circuit.
In order to establish a resonance topology for obtaining a constant current type output, a self-inductance compensation mode is adopted. And (3) the magnetic coupling system is equivalent to a coupling mutual inductance model. CpCompensating the capacitance for the primary side, CsThe capacitance is compensated for the secondary side. Make CpAnd LpResonance, CsAnd LsResonance, i.e. w2CpLp＝1，w2CsLs1. Thus, a string/string compensation network can be constructed, as shown in fig. 5. Load RoThe input current is equivalent to a current source
Therefore, the system has an output constant current characteristic.
And for the inverter with current source type input end, the equivalent current source IinAs shown in fig. 6. Using Thevenin theorem to connect current source IinAnd a capacitor CpThe parallel circuit is equivalent to a voltage source
And a capacitor CpThe series arrangement, as shown in FIG. 7, makes CpAnd LpResonance, CsAnd LsResonates and thus constitutes a parallel/serial compensation network. Load RoThe input current is equivalent to a current source
Therefore, the system has an output constant current characteristic.
In SS and PS compensation structures CpAnd LpThe resonance function is to make the circuit realize constant current output, and CsAnd LsThe effect of the resonance is to reduce the reactive component of the circuit and thereby increase the overall efficiency of the system. Therefore, as long as C can be ensuredpAnd LpAnd the system can realize constant current output by resonance. The traditional phase-locked loop control technology cannot guarantee CpAnd LpResonates and thus constant current output cannot be obtainedThe characteristic of (c).
Therefore, as shown in fig. 11, this embodiment further provides an on-line frequency detection circuit with SS and PS compensation structures for wireless power transmission constant current output, which includes a magnetic coupling system, and a dc voltage source, a full-bridge inverter circuit, and a primary compensation capacitor C are disposed on a transmitting side of the magnetic coupling systempA secondary compensation capacitor C is arranged on the receiving side of the magnetic coupling systemsThe power supply comprises a rectifying circuit, a switching tube S5, a filter circuit and a load including a lithium battery pack; the device also comprises a primary side control module, a primary side PWM driving circuit, a current detection circuit, a secondary side control module and a secondary side PWM driving circuit;
two ends of the direct current voltage source are respectively connected with two input ends of the full-bridge inverter circuit, and one output end of the full-bridge inverter circuit passes through the primary side compensation capacitor CpThe other output end of the full-bridge inverter circuit is connected to the other end of the transmitting side of the magnetic coupling system; one end of the receiving side of the magnetic coupling system is compensated by the secondary side compensation capacitor CsThe switch tube S5 is connected to one input end of the rectifying circuit, the other end of the receiving side of the magnetic coupling system is connected to the other input end of the rectifying circuit, and the output end of the rectifying circuit is connected to a load including a lithium battery pack through a filter circuit;
the input end of the current detection circuit is connected to the transmitting side of the magnetic coupling system, the output end of the current detection circuit is connected to the control module, and the control module is connected to the full-bridge inverter circuit through the PWM driving circuit and used for controlling the work of a switch tube in the full-bridge inverter circuit.
The transmitting side is a direct-current voltage source, and a full-bridge inverter circuit is formed by adding four groups of switching tubes S1-S4; the current of the receiving side passes through the L from the rectifier module1、C0The formed filter circuit is transmitted to loads such as a lithium battery pack and the like. Before starting charging, the switching tube S5 is turned off.
In this implementation, the input end of the current detection circuit is connected to the transmitting side of the magnetic coupling system, the output end is connected to the primary side control module, the primary side control module is connected to the full-bridge inverter circuit through the primary side PWM driving circuit for controlling the operation of the switching tube in the full-bridge inverter circuit, the primary side control module is in communication connection with the secondary side control module, the secondary side control module is connected to the switching tube and the switching tube S5 in the rectification circuit through the secondary side PWM driving circuit for controlling the operation of the switching tube in the rectification circuit and the operation of the switching tube S5.
In this embodiment, the detection method of the frequency online detection circuit based on the wireless power transmission constant current output described above specifically includes: by obtaining the primary compensation capacitance C in real timepSelf-inductance L of primary coil of magnetic coupling systempThe working frequency of the full-bridge inverter circuit is equal to the resonant frequency, and constant current output is realized.
Wherein, the real-time detection primary side compensation capacitor CpSelf-inductance L of primary coil of magnetic coupling systempThe resonant frequency of (a) specifically comprises the steps of:
step S1: after the communication between the primary side control module and the secondary side control module is successful, the secondary side control module controls the switching tube S5 to be switched off so that the receiving side of the magnetic coupling system is opened;
step S2: applying PWM to the driving circuit of the primary side switch tubes S1, S4 or S2, S3 to turn on the switch tubes S1, S4 or S2, S3, so that a direct current voltage source is applied to the compensation capacitor and the magnetic coupling system; meanwhile, because no current passes through the secondary side, no magnetic flux can be generated on the primary side, namely, the primary side only has coil self-inductance Lp. Since the winding resistance r in an actual circuit is not negligible, the resulting circuit is an RLC second order circuit. Current I flowing through the circuitLThe waveform is a sine wave with attenuated amplitude and constant period, but the period is approximately equal to the resonance period of the LC loop due to the smaller value of r. Can obtain I by detectionLIs C, the frequency ispAnd LpIs also the inverter operating frequency that needs to be employed. Wherein, a constant current output type transmitting side primary side equivalent circuit SS compensation structure and a PS compensation structure are respectively shown in fig. 12 and fig. 13;
step S3: detecting current I of transmitting side of magnetic coupling system through primary side compensation capacitorLDetecting ILFrequency of (I) ofLHas a frequency of CpAnd LpThe resonant frequency of (c).
In this embodiment, the step S3 is to use a hall sensor or a current transformer to detect the current I flowing through the primary compensation capacitorLThen converting the voltage signal into a voltage signal with amplitude changing from zero up to zero, then entering a zero-crossing comparison circuit, outputting high level at the moment of positive voltage, and outputting zero at the moment of negative voltage to obtain a square wave pulse signal with the same frequency and phase as the sine wave; the level output by the zero-crossing comparison circuit meets the input voltage range of the primary side control module through the voltage division circuit, and finally the signal enters the CAP capture unit of the control module to obtain the count value of a period waveform, calculate the time of the period, and convert the period into the resonant frequency. The constant-current output type emitting side primary side equivalent circuit is similar to the constant-voltage output type, and the difference is that the primary side is self-inductance at the moment; the frequency tracking scheme is consistent with the constant voltage output type.
Preferably, in this embodiment, the control module may adopt a DSP, and the model is TMS320F 28335. A single chip microcomputer can also be used.
In summary, the conditions for realizing constant voltage output for the SP and PP compensation structure are as follows: make CpAnd LpkGenerating resonance; the conditions for realizing constant current output by the SS and PS compensation structures are as follows: make CpAnd LpResonance is generated. Thus, detecting C in real timepAnd LpkResonant frequency (SP, PP compensation structure) and CpAnd LpAnd when the operating frequency of the inverter is made equal to the resonance frequency (SS, PS compensation structure), the system can obtain a constant voltage or constant current output characteristic.
In particular, in the present embodiment, as shown in fig. 14, the zero-cross comparison circuit uses a low-delay comparator for adjusting the sinusoidal signal into a square-wave signal, and the power voltage V of the comparatorCCIs 5V. The non-inverting input end of the comparator A1 is the voltage output by the Hall sensor; the inverting input of a1 is connected to ground. When the non-inverting input of a1 is at a higher potential than the inverting input, the output of the comparator will be high. When the potential of the non-inverting input end is lower than that of the inverting input end, the comparator outputs low level.
As shown in fig. 15, the square wave is passed through the voltage divider circuits of R1 and R2 to obtain a square wave with an output amplitude of 3V, and the square wave can be sent to the CAP capture unit of the DSP, and then the signal captured at the CAP end is determined by the DSP. The CAP can capture the edges of the input waveform and record the time between edges so that the CAP can be used to measure the period of the digital signal. The CAP capture unit is set to a rising edge triggered mode, the universal timer is set to a time base, and one count period is denoted as T0. The value of the counter N1 captured on the second rising edge is scaled to the period of the voltage frequency by T N1 × T0. The resonance frequency f at this time is calculated to be 1/T. Finally, the DSP sends PWM wave with the same frequency as the resonant frequency to a switch tube driving circuit at the transmitting side, so that the switch tubes S1-S4 work under the oscillation frequency the same as the natural frequency, and the purpose of frequency tracking is achieved.
It is worth mentioning that the utility model discloses a protection is hardware architecture, does not require protection as to control method and detection method. The above is only a preferred embodiment of the present invention. However, the present invention is not limited to the above embodiments, and any equivalent changes and modifications made according to the present invention do not exceed the scope of the present invention, and all belong to the protection scope of the present invention.
Claims (4)
1. The wireless power transmission constant-voltage output frequency online detection circuit with the SP and PP compensation structures comprises a magnetic coupling system and is characterized in that a direct-current voltage source, a full-bridge inverter circuit and a primary side compensation capacitor C are arranged on the transmitting side of the magnetic coupling systempA secondary compensation capacitor C is arranged on the receiving side of the magnetic coupling systemmThe lithium battery pack comprises a rectifier circuit, a filter circuit and a load comprising the lithium battery pack; the device also comprises a primary side control module, a primary side PWM driving circuit, a current detection circuit, a secondary side control module and a secondary side PWM driving circuit;
two ends of the direct current voltage source are respectively connected with two input ends of the full-bridge inverter circuit, and one output end of the full-bridge inverter circuit passes through the primary side compensation capacitor CpConnected to one end of the transmitting side of the magnetic coupling system and the other end of the full-bridge inverter circuitThe output end is connected to the other end of the transmitting side of the magnetic coupling system; receiving side of magnetic coupling system and secondary side compensation capacitor CmThe output ends of the rectifying circuits are connected to loads including the lithium battery pack through the filter circuit;
the input end of the current detection circuit is connected to the transmitting side of the magnetic coupling system, the output end of the current detection circuit is connected to the primary side control module, the primary side control module is connected to the full-bridge inverter circuit through the PWM driving circuit and used for controlling the work of a switching tube in the full-bridge inverter circuit, the secondary side control module is in communication connection with the primary side control module, and the secondary side control module is connected to the rectifying circuit through the secondary side PWM driving circuit and used for controlling the work of the switching tube in the rectifying circuit.
2. The on-line frequency detection circuit for the constant voltage output in wireless power transmission according to claim 1, wherein the current detection circuit comprises a hall sensor or a current transformer, a zero-crossing comparison circuit and a voltage division circuit which are connected in sequence, the hall sensor or the current transformer is used for detecting the current of the transmitting side of the magnetic coupling system, and the output of the voltage division circuit is connected to the primary side control module; the primary side control module adopts a DSP or a singlechip.
3. The frequency online detection circuit with the SS and PS compensation structures for wireless power transmission constant current output comprises a magnetic coupling system and is characterized in that a direct current voltage source, a full-bridge inverter circuit and a primary side compensation capacitor C are arranged on the transmitting side of the magnetic coupling systempA secondary compensation capacitor C is arranged on the receiving side of the magnetic coupling systemsThe power supply comprises a rectifying circuit, a switching tube S5, a filter circuit and a load including a lithium battery pack; the device also comprises a primary side control module, a primary side PWM driving circuit, a current detection circuit, a secondary side control module and a secondary side PWM driving circuit;
two ends of the direct current voltage source are respectively connected with two input ends of the full-bridge inverter circuit, and one output end of the full-bridge inverter circuit passes through the primary side compensation capacitor CpConnected to a magnetic coupling systemThe other output end of the full-bridge inverter circuit is connected to the other end of the transmitting side of the magnetic coupling system; one end of the receiving side of the magnetic coupling system is compensated by the secondary side compensation capacitor CsThe switch tube S5 is connected to one input end of the rectifying circuit, the other end of the receiving side of the magnetic coupling system is connected to the other input end of the rectifying circuit, and the output end of the rectifying circuit is connected to a load including a lithium battery pack through a filter circuit;
the input end of the current detection circuit is connected to the transmitting side of the magnetic coupling system, the output end of the current detection circuit is connected to the primary side control module, the primary side control module is connected to the full-bridge inverter circuit through the primary side PWM driving circuit and used for controlling the work of a switch tube in the full-bridge inverter circuit, the primary side control module is in communication connection with the secondary side control module, and the secondary side control module is connected to the switch tube in the rectifying circuit and the switch tube S5 through the secondary side PWM driving circuit and used for controlling the work of the switch tube in the rectifying circuit and the work of the switch tube S5.
4. The on-line frequency detection circuit for the constant current output in wireless power transmission according to claim 3, wherein the current detection circuit comprises a Hall sensor or a current transformer, a zero-crossing comparison circuit and a voltage division circuit which are connected in sequence, the Hall sensor or the current transformer is used for detecting the current of the transmitting side of the magnetic coupling system, and the output of the voltage division circuit is connected to the primary side control module; the primary side control module adopts a DSP or a singlechip.
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Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110554236A (en) * | 2019-09-30 | 2019-12-10 | 福州大学 | Frequency online detection method for constant-voltage or constant-current output of wireless power transmission |
| CN112994192A (en) * | 2021-04-30 | 2021-06-18 | 上海海事大学 | Constant-current/constant-voltage output method for wireless charging system |
| CN113103886A (en) * | 2021-03-09 | 2021-07-13 | 桂林电子科技大学 | Novel automatic charging method and device for unmanned aerial vehicle |
| WO2024180751A1 (en) * | 2023-03-02 | 2024-09-06 | スミダコーポレーション株式会社 | Current sensor circuit |
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2019
- 2019-09-30 CN CN201921655393.4U patent/CN211236016U/en not_active Expired - Fee Related
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110554236A (en) * | 2019-09-30 | 2019-12-10 | 福州大学 | Frequency online detection method for constant-voltage or constant-current output of wireless power transmission |
| CN110554236B (en) * | 2019-09-30 | 2023-12-19 | 福州大学 | Frequency online detection method for constant voltage or constant current output of wireless power transmission |
| CN113103886A (en) * | 2021-03-09 | 2021-07-13 | 桂林电子科技大学 | Novel automatic charging method and device for unmanned aerial vehicle |
| CN112994192A (en) * | 2021-04-30 | 2021-06-18 | 上海海事大学 | Constant-current/constant-voltage output method for wireless charging system |
| CN112994192B (en) * | 2021-04-30 | 2024-08-06 | 上海海事大学 | Constant-current/constant-voltage output method for wireless charging system |
| WO2024180751A1 (en) * | 2023-03-02 | 2024-09-06 | スミダコーポレーション株式会社 | Current sensor circuit |
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