CN110071562B - Transmitting side switching hybrid topology constant-current constant-voltage induction type wireless charging method and system - Google Patents

Abstract

The invention discloses a transmission-side switching hybrid topology constant-current constant-voltage inductive wireless charging method and system, comprising: after charging is started, the high-frequency inverter connects the primary series compensation inductance, the primary constant current compensation capacitor and the charging induction coil The sending side winding, the receiving side induction winding and the rectifier charge the battery load with constant current; in the constant current or constant voltage charging stage, the root mean square value of the output current of the high frequency inverter is detected in real time, and the charging voltage of the battery load is estimated or Judging whether the battery load is fully charged and automatically cut off by the battery management system BMS; when it is detected that the BMS is cut off or the battery load is fully charged, the constant voltage charging circuit is disconnected, and the inverter power supply output is automatically disconnected to stop charging. The invention does not need the charging voltage communication detection facility on the receiving side, has simple structure, convenient control, stable performance, small reactive power loss, relatively low requirements on the capacity of the inverter, and low device manufacturing cost.

Description

A sending side switching hybrid topology constant current constant voltage inductive wireless charging method and its system

technical field

The invention relates to a sending-side switching hybrid topology constant-current constant-voltage inductive wireless charging method and system, belonging to the technical field of wireless charging.

Background technique

Inductive wireless power transfer is a technology that can safely, efficiently, and conveniently deliver power to loads through magnetic coupling without wire connections, and has received extensive attention from the scientific and academic communities in recent decades. This emerging and promising technology is developing rapidly and has been widely used in many commercial fields, such as train power supplies, electric vehicles, underwater systems, consumer electronics, biomedical devices, and other industrial fields. In general, ordinary loads usually only need constant current or constant voltage power supply mode. However, as a special load, the battery usually needs to include constant current and constant voltage two-stage charging at the same time, so as to prolong the service life of the battery and the number of charge and discharge times. Normally, the constant current charging mode is adopted at the initial stage of battery charging, and the battery charging voltage rises rapidly; when the battery charging voltage rises to the preset charging voltage, the constant voltage charging mode is adopted, and the battery charging current gradually decreases to the cut-off charging current during this process. The battery is fully charged and charging is complete. At present, in most of the wireless charging systems for battery charging, complex control schemes are usually used to monitor battery charging information in real time and feed the information back to the controller on the sending side through the wireless communication module. This not only increases the complexity of the control, but also increases the system loss and application cost. Another solution is to use a switching topology and use the internal characteristics of the circuit to achieve constant current and constant voltage output of the system. This solution is usually divided into two types: 1. The topological structure is switched on the sending side to achieve constant current and constant voltage output. The disadvantage is that the bilateral wireless communication module needs to feed back the battery charging information in real time. 2. Switch topology on the receiving side to achieve constant current and constant voltage output. The disadvantage is that more reactive components are installed on the receiving side, which increases the weight and cost of the receiving side, and violates the principle of compactness of the receiving side.

Contents of the invention

The invention provides a sending side switching hybrid topology constant current constant voltage inductive wireless charging method and system, and the system does not need a wireless communication module, the receiving side has fewer reactive components, the structure is simple, the cost is low, and complex control technology is not required.

The purpose of the present invention is achieved like this:

A sending side switching hybrid topology constant current constant voltage inductive wireless charging method, characterized in that it comprises the following steps:

Step 1. After charging is started, the high-frequency inverter charges the battery load with a constant current through the series connection of the primary series compensation inductor, the primary constant current compensation capacitor, the sending side winding of the charging induction coil, the receiving side induction winding and the rectifier;

Step 2. In the constant current charging stage, detect the root mean square value of the output current of the high frequency inverter in real time, and estimate the charging voltage of the battery load;

Step 3, judging whether the charging voltage of the battery load satisfies the switching condition (3) of the transition process from constant current to constant voltage, and the switching condition is determined by formula (1);

In formula (1), I _I is the root mean square value of the output current of the high-frequency inverter H, U _B is the charging voltage of the battery load, R _P is the equivalent parasitic resistance of the sending side winding of the charging induction coil, and R _S is the charging voltage The equivalent parasitic resistance of the induction winding on the receiving side of the induction coil, M is the mutual inductance value of the charging induction coil, ω is the angular frequency, U _D is the DC input voltage value of the inverter; when the switching process from constant current to constant voltage is not satisfied condition, continue step 2 to the constant current stage until the switching condition is met, then go to step 4;

Step 4. When the switching condition from constant current to constant voltage is satisfied, automatically switch to the constant voltage charging circuit to realize constant voltage charging;

Step 5. In the constant voltage charging stage, detect the root mean square value of the output current of the high frequency inverter in real time, judge whether the battery load is fully charged and is automatically cut off by the battery management system, and detect the root mean square value of the output current of the high frequency inverter including : Through the current sensor and controller, real-time data acquisition of the instantaneous value of the output current of the high-frequency inverter; determine whether the battery load is fully charged and is automatically cut off by the battery management system;

The judging whether the battery load is fully charged and automatically cut off by the battery management system is based on the fact that during the constant voltage charging process, when the battery load is full and automatically cut off by the battery management system, that is, the system is in a no-load state, at this time the high frequency inverter outputs The root mean square value of the current is a fixed value and is determined by formula (2);

In formula (2), R _R is the equivalent parasitic resistance of the primary series compensation inductor;

In order to ensure that when the battery load is fully charged and is automatically cut off by the battery management system, the inverter on the sending side is no longer providing power output, and the charging termination condition is set to be determined by formula (3);

Step 6. When it is detected that the battery management system is cut off or the battery load is fully charged, the constant voltage charging circuit is disconnected, and the power supply output of the inverter is automatically disconnected, and the charging is stopped (6).

In the above-mentioned method for inductive wireless charging with hybrid topology switching at the transmitting side, constant current and constant voltage, in step 1,

The output of the DC power supply is connected to the input of the high-frequency inverter; one end of the output of the high-frequency inverter is connected in series with the primary series compensation inductor, the primary constant current compensation capacitor and one end of the sending side winding of the charging induction coil, and the output of the high-frequency inverter The other end of the charging induction coil is connected to the other end of the sending side winding of the charging induction coil to form a constant current charging sending circuit; one end of the receiving side winding of the charging induction coil is connected to one end of the series-connected secondary compensation capacitor, and the other end of the series-connected secondary compensation capacitor is connected to the rectifier input The other end of the receiving side winding of the charging induction coil is connected to the other end of the input end of the rectifier to form a receiving circuit; the output end of the rectifier is connected to the battery load to realize inductive wireless constant current charging.

In the above-mentioned method for inductive wireless charging with hybrid topology switching at the sending side, in step 2, the root mean square value of the output current of the high-frequency inverter is detected, including: through the current sensor and the controller, the real-time data acquisition is high The instantaneous value of the output current of the high-frequency inverter; calculate the root mean square value of the output current of the high-frequency inverter;

The estimation of the charging voltage of the battery load is based on the approximately linear functional relationship between the root mean square value of the output current of the high-frequency inverter and the charging voltage of the battery during the constant current charging process, and estimates the charging voltage of the battery load.

In the above-mentioned method for inductive wireless charging with hybrid topology switching at the transmitting side, constant current and constant voltage, in step 4,

The constant voltage charging circuit includes a parallel constant voltage charging circuit and a series constant voltage charging circuit; the parallel constant voltage charging circuit is composed of a primary constant voltage compensation capacitor _CR connected in series with a switching switch S ₁ , and T is connected to the primary series compensation inductance _LR and The connection point of the primary constant current compensation capacitor C _PA and the other end of the high frequency inverter H; and the control terminal of the switch S ₁ is connected to the controller K; the series constant voltage charging circuit is composed of the primary constant voltage compensation capacitor C _PB and the switch The switch S ₂ is connected in series and parallel to the primary constant current compensation capacitor C _PA , and the control terminal of the switching switch S ₂ is connected to the controller K;

The automatic switching to the constant voltage charging circuit is when the preset root mean square value of the output current of the high frequency inverter H satisfies the formula (1), the controller will connect the parallel constant voltage charging circuit and the series constant voltage charging circuit, That is, the switching switches S ₁ and S ₂ are closed to realize the transition of the battery load from the constant current charging process to the constant voltage charging process.

In the above-mentioned method of switching the hybrid topology constant current constant voltage inductive wireless charging method on the sending side, step 6, when it is detected that the battery management system is cut off or the battery load is fully charged, the constant voltage charging circuit is disconnected, and the inverter is automatically disconnected The power supply output of the device stops charging;

The disconnection of the constant voltage charging circuit is disconnecting the parallel constant voltage charging circuit and the series constant voltage charging circuit, that is: disconnecting the switching switches S1 and _{S2 ;}

The process of automatically stopping the charging is that when the preset root mean square value of the output current of the high-frequency inverter H satisfies the formula, the controller will stop the power supply output of the inverter, that is, stop charging.

The above-mentioned method for switching a hybrid topology constant current and constant voltage inductive wireless charging method on the sending side, including a DC power supply, a high frequency inverter, a sending unit, a charging induction coil, a receiving unit, a current sensor, a controller, a rectifier and a battery load ,in,

The high-frequency inverter inverts the input DC power and outputs it as high-frequency AC power, wirelessly inductively couples and transmits high-frequency AC power to the receiving unit through the sending unit and charging induction coil, and converts it into DC through the rectifier to charge the battery load with constant current; The current sensor and controller detect the RMS value of the output current of the high-frequency inverter in real time, and estimate the charging voltage of the battery load. When the RMS value of the output current of the high-frequency inverter satisfies formula (1), the controller will The parallel constant voltage charging circuit and the series constant voltage charging circuit are connected, that is, the switching switches S ₁ and S ₂ are closed to realize the transformation of the battery load from the constant current charging process to the constant voltage charging process; when the output current of the high frequency inverter is uniform When the square root value satisfies the formula (3), the constant voltage charging circuit is disconnected, and the power supply output of the inverter is automatically disconnected, and the battery load charging is stopped;

The sending unit includes a constant current charging circuit, a parallel constant voltage charging circuit and a series constant voltage charging circuit; the receiving unit includes a sequentially connected receiving circuit, a rectifier _D and a battery load equivalent to an internal resistance _RB connected in series with an ideal voltage source UB;

The charging induction coil includes a sending side winding with a self-inductance parameter of L _P , a resistance parameter of R _P and a receiving side winding with a self-inductance parameter of L _S and a resistance parameter of R _S , and the mutual inductance parameter of the charging induction coil is M by the formula ( 4) determine;

In the formula, I _B is the set constant charging current, ω is the resonant angular frequency;

The constant current charging circuit is composed of the primary series compensation inductor _LR and the primary constant current compensation capacitor C _PA connected in series, the head and the tail are respectively connected to one end of the output of the high-frequency inverter and one end of the sending side winding _LP of the charging induction coil, and the charging induction coil The other end of the winding L _P on the sending side of the coil is connected to the other end of the output of the high-frequency inverter;

The primary series compensation inductance _LR is shown in formula (5);

In the formula, U _B is the set constant charging voltage;

Described primary compensation capacitor _CPA is shown in formula (6);

The series constant voltage charging circuit is composed of a primary constant voltage compensation capacitor C _PB connected in series with a switch S2 _; connected in parallel to the primary constant current compensation capacitor C _PA ; one end of the primary constant current compensation capacitor C _PA is connected to the primary series compensation inductor L _R , The other end is connected to the sending side winding L _P of the charging induction coil; the other end of the sending side winding L _P of the charging induction coil is connected to the other end of the output of the high _- frequency inverter; and the control end of the switching switch S2 is connected to the controller K. ;

The primary constant voltage compensation capacitor C _PB is shown in formula (7);

The parallel constant voltage charging circuit is composed of a primary constant voltage compensation capacitor C _R connected in series with a switch S1; _one end is T-shaped connected to the connection point of the primary series compensation inductance _LR and the primary constant current compensation capacitor C _PA , and the other end is connected to the high frequency The other end of the inverter H and the other end of the sending side winding L _P of the charging induction coil; and the control end _of the switch S1 is connected to the controller K;

The primary constant voltage compensation capacitor C _R is shown in formula (8);

The receiving circuit is formed by connecting the secondary compensation capacitor C _S to the input end of the rectifier in parallel after the self-inductance parameter L _S and the resistance parameter R _S of the receiving side winding of the charging induction coil are connected in series;

Described secondary compensation electric capacity C _S is shown by formula (9);

In the above-mentioned method of switching the hybrid topology constant current and constant voltage inductive wireless charging method _on the sending side, the current sensor and the controller cooperate to control the closing and opening _of the switching switch S1 and the switching switch S2, so as to realize the constant current charging process and the constant voltage charging method. The conversion of the charging process, and the control of the end of charging;

_The changeover switch S1 and the changeover switch S2 are composed of _a power electronic switch device and a trigger control drive circuit;

The current sensor is not distorted when detecting the MHz-level high-frequency current output by the high-frequency inverter; the controller includes an analog input circuit, an analog-to-digital conversion circuit, an electrical physical quantity calculation program, a detection and control program, and a switch output circuit, isolation and interface circuit with trigger control drive circuit.

The system has the following technical characteristics and advantages:

1. The present invention only needs to introduce two switching switches on the sending side to change the circuit topology on the sending side to form a constant current and constant voltage switching circuit, which has a simple circuit structure and low cost. When working, only a simple control switch is needed, no complicated control circuit is required, and the operation is simple, convenient and reliable.

2. In the circuit topology of the present invention, when the system is outputting constant current and constant voltage, the output voltage and current of the inverter are basically in the same phase, so that the inverter hardly injects reactive power, so the system loss is small, and the inverter The capacity requirement of the transformer is reduced.

3. The present invention can output constant current and constant voltage irrelevant to the load at the same frequency, meeting the requirements of initial constant current charging and later constant voltage charging of the battery. The system works at one frequency point, and there will be no frequency bifurcation phenomenon, which ensures the stable operation of the system.

4. The present invention detects the root mean square value of the output current of the high-frequency inverter in real time, evaluates the charging voltage of the system in the constant current charging stage in real time, and estimates the charging termination condition in the constant voltage charging stage, without the need to receive Real-time communication feedback of charging information from side to sending side, therefore, the wireless communication module can be eliminated. Not only the cost is saved, but also the adverse effect caused by the communication interference on the charging process is avoided.

5. The receiving side of the present invention has only one capacitive element, which is simple and portable, and is very suitable for some special application scenarios, such as biomedicine, consumer electronics, etc.

Description of drawings

Fig. 1 is a flowchart of a method embodiment involved in the present invention.

Fig. 2 is a schematic circuit diagram of the system structure of the embodiment of the system involved in the present invention.

Fig. 3 is a schematic diagram of the constant current output circuit of the system embodiment involved in the present invention.

Fig. 4 is a schematic diagram of the constant voltage output circuit of the system embodiment involved in the present invention.

detailed description

Below in conjunction with accompanying drawing and embodiment describe in detail:

1. Sending side switching hybrid topology constant current constant voltage inductive wireless charging method

Figure 1 shows the flow chart of an embodiment of the method for inductive wireless charging with hybrid topology switching at the sending side with constant current and constant voltage, which can be seen from Figure 1:

In the first step, after charging is started, the high-frequency inverter charges the battery load with a constant current through the series connection of the primary series compensation inductor, the primary constant current compensation capacitor, the sending side winding of the charging induction coil, the receiving side induction winding and the rectifier (1):

The output of the DC power supply is connected to the input of the high-frequency inverter; one end of the output of the high-frequency inverter is connected in series with the primary series compensation inductor, the primary constant current compensation capacitor and one end of the sending side winding of the charging induction coil, and the high-frequency inverter The other end of the output of the charging induction coil is connected to the other end of the sending side winding of the charging induction coil to form a constant current charging sending circuit; one end of the receiving side winding of the charging induction coil is connected to one end of the secondary compensation capacitor connected in series, and the other end of the series connected secondary compensation capacitor is connected to One end of the input end of the rectifier and the other end of the receiving side winding of the charging induction coil are connected to the other end of the input end of the rectifier to form a receiving circuit; the output end of the rectifier is connected to the battery load to realize inductive wireless constant current charging.

The second step is to detect the root mean square value of the output current of the high-frequency inverter in real time during the constant current charging stage, and estimate the charging voltage of the battery load (2):

The detection of the root mean square value of the output current of the high-frequency inverter includes: collecting real-time data on the instantaneous value of the output current of the high-frequency inverter through a current sensor and a controller; calculating the root mean square value of the output current of the high-frequency inverter;

The estimation of the charging voltage of the battery load is based on the approximately linear functional relationship between the root mean square value of the output current of the high-frequency inverter and the charging voltage of the battery during the constant current charging process, and estimates the charging voltage of the battery load.

The third step is to judge whether the charging voltage of the battery load meets the switching condition (3) of the transition process from constant current to constant voltage:

The switching condition of the transition process from constant current to constant voltage is determined by formula (1).

In formula (1), I _I is the root mean square value of the output current of the high-frequency inverter H, U _B is the charging voltage of the battery load, R _P is the equivalent parasitic resistance of the sending side winding of the charging induction coil, and R _S is the charging voltage The equivalent parasitic resistance of the induction winding on the receiving side of the induction coil, M is the mutual inductance value of the charging induction coil, ω is the angular frequency, U _D is the DC input voltage value of the inverter.

The fourth step, when the switching condition from constant current to constant voltage is satisfied, automatically switch to the constant voltage charging circuit to realize constant voltage charging (4):

The constant voltage charging circuit includes a parallel constant voltage charging circuit and a series constant voltage charging circuit. The parallel constant voltage charging circuit is composed of the primary constant voltage compensation capacitor C _R and the switch S ₁ in series, and T is connected to the connection point of the primary series compensation inductance _LR and the primary constant current compensation capacitor C _PA and the other end of the high frequency inverter H ; and the control terminal of switch S ₁ is connected to controller K; the series constant voltage charging loop is connected in series with primary constant voltage compensation capacitor C _PB and switch S ₂ , and connected in parallel to primary constant current compensation capacitor C _PA , and switch S The control terminal of ₂ is connected with the controller K;

The automatic switching to the constant voltage charging circuit is when the preset root mean square value of the output current of the high frequency inverter H satisfies the formula (1), the controller will connect the parallel constant voltage charging circuit and the series constant voltage charging circuit, That is, the switching switches S ₁ and S ₂ are closed to realize the transition of the battery load from the constant current charging process to the constant voltage charging process.

Said step five, in the constant voltage charging stage, detect the root mean square value of the output current of the high-frequency inverter in real time, and judge whether the battery load is fully charged and is automatically cut off by the battery management system (5):

The detection of the root mean square value of the output current of the high-frequency inverter includes: collecting real-time data on the instantaneous value of the output current of the high-frequency inverter through the current sensor and the controller; judging whether the battery load is fully charged and automatically cut off by the battery management system;

The judging whether the battery load is fully charged and automatically cut off by the battery management system is based on the fact that during the constant voltage charging process, when the battery load is full and automatically cut off by the battery management system, that is, the system is in a no-load state, at this time the high frequency inverter outputs The root mean square value of the current is a fixed value and is determined by formula (2).

In formula (2), R _R is the equivalent parasitic resistance of the primary series compensation inductor.

In order to ensure that when the battery load is fully charged and is automatically cut off by the battery management system, the inverter at the sending side does not provide power output, the charging termination condition is set to be determined by formula (3).

Step 6: When it is detected that the battery management system is cut off or the battery load is fully charged, the constant voltage charging circuit is disconnected, and the inverter power supply output is automatically disconnected, and charging is stopped (6):

The disconnection of the constant voltage charging circuit means disconnecting the parallel constant voltage charging circuit and the series constant voltage charging circuit, that is, disconnecting the switching switches S ₁ and S ₂ .

The process of automatically stopping the charging is that when the preset root mean square value of the output current of the high-frequency inverter H satisfies the formula (3), the controller will stop the power supply output of the inverter, that is, stop charging.

The sending side switching hybrid topology constant current constant voltage inductive wireless charging system is characterized in that it includes a DC power supply, a high frequency inverter, a sending unit, a charging induction coil, a receiving unit, a current sensor, a controller, a rectifier and a battery load.

The high-frequency inverter inverts the input DC power and outputs it as high-frequency AC power, wirelessly inductively couples and transmits high-frequency AC power to the receiving unit through the sending unit and charging induction coil, and converts it into DC through the rectifier to charge the battery load with constant current; The current sensor and controller detect the RMS value of the output current of the high-frequency inverter in real time, and estimate the charging voltage of the battery load. When the RMS value of the output current of the high-frequency inverter satisfies formula (1), the controller will The parallel constant voltage charging circuit and the series constant voltage charging circuit are connected, that is, the switching switches S ₁ and S ₂ are closed to realize the transformation of the battery load from the constant current charging process to the constant voltage charging process; when the output current of the high frequency inverter is uniform When the square root value satisfies the formula (3), the constant voltage charging circuit is disconnected, and the power supply output of the inverter is automatically disconnected, and the battery load charging is stopped.

2. Transmitter switching hybrid topology constant current constant voltage inductive wireless charging system

The schematic diagram of the system structure circuit diagram of the system embodiment system structure involved in the invention shown in Fig. 2 can be seen from Fig. 2:

The system structure includes: DC power supply, high frequency inverter, sending unit, charging induction coil, receiving unit, current sensor, controller, rectifier and battery load.

Working principle: The high-frequency inverter inverts the input DC power and outputs it as high-frequency AC power, wirelessly inductively couples and transmits high-frequency AC power to the receiving unit through the sending unit and the charging induction coil, and transforms it into DC through the rectifier to supply the battery with a constant load. Current charging; the current sensor and controller detect the output current root mean square value of the high-frequency inverter in real time, and estimate the charging voltage of the battery load. When the high-frequency inverter output current root mean square value satisfies formula (1), The controller connects the parallel constant voltage charging circuit and the series constant voltage charging circuit, that is, closes the switching switches S ₁ and S ₂ to realize the change of the battery load from the constant current charging process to the constant voltage charging process; when the high frequency inverter When the root mean square value of the output current satisfies the formula (3), the constant voltage charging circuit is disconnected, and the power supply output of the inverter is automatically disconnected, and the charging of the battery load is stopped.

The sending unit includes a constant current charging circuit, a parallel constant voltage charging circuit and a series constant voltage charging circuit;

The receiving unit includes a receiving circuit connected in sequence, a rectifier D and a battery load equivalent to _a series connection of an internal resistance _RB and an ideal voltage source UB.

The charging induction coil includes a sending side winding with a self-inductance parameter of L _P , a resistance parameter of R _P and a receiving side winding with a self-inductance parameter of L _S and a resistance parameter of R _S , and the mutual inductance parameter of the charging induction coil is M by the formula ( 4) OK.

In formula (4), I _B is the set constant charging current, and ω is the resonant angular frequency.

The constant current charging circuit is composed of the primary series compensation inductor _LR and the primary constant current compensation capacitor C _PA connected in series, the head and the tail are respectively connected to one end of the output of the high-frequency inverter and one end of the sending side winding _LP of the charging induction coil, and the charging induction coil The other end of the winding L _P on the sending side of the coil is connected to the other end of the output of the high frequency inverter.

The primary series compensation inductance _LR is shown by formula (5).

In formula (5), _UB is the set constant charging voltage.

The primary compensation capacitor C _PA is shown by formula (6).

The series constant voltage charging circuit is composed of a primary constant voltage compensation capacitor C _PB connected in series with a switch S2 _; connected in parallel to the primary constant current compensation capacitor C _PA ; one end of the primary constant current compensation capacitor C _PA is connected to the primary series compensation inductor L _R , The other end is connected to the sending side winding L _P of the charging induction coil; the other end of the sending side winding L _P of the charging induction coil is connected to the other end of the output of the high _- frequency inverter; and the control end of the switching switch S2 is connected to the controller K. .

The primary constant voltage compensation capacitor C _PB is shown by formula (7).

The parallel constant voltage charging circuit is composed of a primary constant voltage compensation capacitor C _R connected in series with a switch S1; _one end is T-shaped connected to the connection point of the primary series compensation inductance _LR and the primary constant current compensation capacitor C _PA , and the other end is connected to the high frequency The other end of the inverter H and the other end of the sending side winding L _P of the charging induction coil; and the control end _of the switching switch S1 is connected to the controller K.

The primary constant voltage compensation capacitor _CR is shown by formula (8).

The receiving circuit is formed by connecting the secondary compensation capacitor C _S to the input terminal of the rectifier in parallel with the self-inductance parameter L _S and the resistance parameter R _S of the receiving side winding of the charging induction coil connected in series.

The secondary compensation capacitor _CS is shown by formula (9).

_The current sensor and the controller cooperate to control the closing and opening _of the switching switch S1 and the switching switch S2, so as to realize the conversion between the constant current charging process and the constant voltage charging process, and the control of the end of charging.

_The changeover switch S1 and the changeover switch S2 are composed of _a power electronic switch device and a trigger control drive circuit.

The current sensor is not distorted when detecting the MHz-level high-frequency current output by the high-frequency inverter.

The controller includes an analog input circuit, an analog-to-digital conversion circuit, an electric physical quantity calculation program, a detection and control program, a switch output circuit, an isolation and an interface circuit with a trigger control drive circuit.

The schematic diagram of the constant current output circuit of the system embodiment involved in the present invention shown in Fig. 3 can be seen from Fig. 3:

For simplicity, R _R , R _P and R _S are very small and can be ignored, and the circuit parameters can be simplified as shown in formula (10).

Among them, X _P and X _S represent the equivalent reactance of the sending side and receiving side circuits respectively.

Write the system of equations according to Kirchhoff's voltage law (KVL):

Substituting formula (10) into formula (11) gives the solution:

与时变的负载电阻值无关，即：Obviously, when X _P =0 in formula (12), the output current of the system

independent of the time-varying load resistance value, i.e.:

Further, the total system input impedance can be derived as:

According to formula (12), when X _P =0 and X _S =0 are satisfied, the system can realize constant current output.

When ignoring the influence of mutual inductance, the conditions to satisfy the pure resistive input load are shown in formula (15).

The schematic diagram of the constant voltage output circuit of the system embodiment involved in the present invention shown in Fig. 4 can be seen from Fig. 4:

When the switches S1 and S2 in Figure ₂ are closed, the circuit in Figure ₄ enters the constant voltage charging mode.

Since R _R , R _P and R _S are very small, they can be ignored for simplicity, and the simplified circuit parameters are shown in formula (16).

Write the system of equations according to Kirchhoff's voltage law (KVL):

Substituting formula (16) into formula (17) gives the solution:

The system output voltage can be derived from:

与时变的负载电阻值无关，即：It can be seen that when A=0, the system output voltage

independent of the time-varying load resistance value, i.e.:

A＝Y _L Y _C (Y _M +Y _S )+(Y _L +Y _C )(Y _P Y _M +Y _M Y _S +Y _P Y _S )＝0 (21)

Formula (24) can be expressed as:

Substitute (16) into (22) to get:

According to formula (20) and formula (23), the output voltage of the system can be deduced as:

Further, the total system input impedance can be derived as:

According to formula (25), when formula (26) is satisfied, the total input impedance of the system is purely resistive:

Y _C +Y _P +Y _M ＝0 (26)

Substitute (16) into (26) to get:

Ultimately, the total system input impedance is:

In summary, when formula (15) is satisfied, the topology in Figure 3 can obtain a stable constant current output, and can realize pure resistive input impedance; when formula (23) and formula (27) are satisfied, the circuit in Figure 4 can Obtain stable constant voltage output, and can realize pure resistive input impedance.

The relationship between the fundamental effective value of the output voltage of the inverter and its input DC voltage is:

The relationship between the fundamental RMS value of the input voltage U _O and the current I _O of the rectification filter circuit, the output voltage U _B and the current I _B is:

Substitute equations (29) and (30) into equation (13) to find the mutual inductance value M:

Substitute equations (32), (33) and (34) into equation (27) to obtain the primary series compensation inductance _LR value:

According to equations (26) and (35), the value of the primary constant voltage compensation capacitor C _R and the value of the secondary compensation capacitor C _S are obtained:

According to (15), (27), (32) and (33), the value of the primary constant current compensation capacitor C _PA and the value of the primary constant voltage compensation capacitor C _PB are obtained respectively:

Generally speaking, when the controller controls _S1 and S2 to be turned off at the same time, the system works in the constant current charging mode _; when the controller controls S1 and _S2 to be turned _on at the same time, the system works in the constant voltage charging mode.

The above descriptions are only preferred embodiments of the present invention, and do not limit the present invention in any form. Although the present invention has been disclosed above with preferred embodiments, it is not intended to limit the present invention. Any person familiar with the art, without departing from the scope of the technical solution of the present invention, can use the methods and technical content disclosed above to make many possible changes and modifications to the technical solution of the present invention, or modify it into an equivalent of equivalent change Example. Therefore, any simple modifications, equivalent changes and modifications made to the above embodiments according to the technical essence of the present invention, which do not deviate from the technical solution of the present invention, still fall within the protection scope of the technical solution of the present invention.

Claims (7)

1. A transmitting side switching mixed topology constant-current constant-voltage induction type wireless charging method is characterized by comprising the following steps:

step 1, after charging is started, a high-frequency inverter charges a battery load with constant current by connecting a primary series compensation inductor, a primary constant current compensation capacitor, a charging induction coil transmitting side winding, a receiving side induction winding and a rectifier in series (1);

step 2, in the constant-current charging stage, detecting the root mean square value of the output current of the high-frequency inverter in real time, and estimating the charging voltage (2) of the battery load;

step 3, judging whether the charging voltage of the battery load meets a switching condition (3) in the process of converting from constant current to constant voltage, wherein the switching condition is determined by a formula (1);

in the formula (1), I _I For high frequency inversionRoot mean square value, U, of the output current of the device H _B Charging voltage for battery load, R _P Equivalent parasitic resistance, R, for the transmitting side winding of the charging induction coil _S Equivalent parasitic resistance of the induction winding at the receiving side of the charging induction coil, M is the mutual inductance value of the charging induction coil, omega is angular frequency, U _D Inputting a voltage value for the inverter direct current; when the switching condition of the conversion process from the constant current to the constant voltage is not met, continuing the constant current stage in the step 2 until the switching condition is met, and turning to the step 4;

step 4, when the switching condition of the process from constant current to constant voltage is met, automatically switching to a constant voltage charging loop to realize constant voltage charging (4);

step 5, in the constant voltage charging stage, detecting the root mean square value of the output current of the high-frequency inverter in real time, judging whether the battery load is fully charged and is automatically cut off by a battery management system (5), wherein the step of detecting the root mean square value of the output current of the high-frequency inverter comprises the following steps: acquiring instantaneous values of output currents of the high-frequency inverter through a current sensor and a controller in real time; judging whether the battery load is fully charged and is automatically cut off by a battery management system;

the judgment of whether the battery load is fully charged and is automatically cut off by the battery management system is carried out according to the principle that in the constant-voltage charging process, when the battery load is fully charged and is automatically cut off by the battery management system, namely the system is in an idle state, the root mean square value of the output current of the high-frequency inverter is a fixed value and is determined by the formula (2);

in the formula (2), R _R Compensating the equivalent parasitic resistance of the inductance for the primary series;

in order to ensure that the transmitting-side inverter is not providing power output after the battery load is fully charged and is automatically cut off by the battery management system, the set charging termination condition is determined by equation (3);

and 6, when the battery management system is cut off or the battery load is fully charged, disconnecting the constant-voltage charging loop, automatically disconnecting the power supply output of the inverter and stopping charging (6).

2. The wireless charging method with the transmission-side switching hybrid topology, constant current and constant voltage induction according to claim 1, wherein in step 1,

the output of the direct current power supply is connected with the input of the high-frequency inverter; one end of the output of the high-frequency inverter is connected with one end of a primary series compensation inductor, a primary constant-current compensation capacitor and one end of a charging induction coil transmitting side winding in series, and the other end of the output of the high-frequency inverter is connected with the other end of the charging induction coil transmitting side winding to form a constant-current charging transmitting loop; one end of the receiving side winding of the charging induction coil is connected with one end of the series secondary compensation capacitor, the other end of the series secondary compensation capacitor is connected with one end of the input end of the rectifier, and the other end of the receiving side winding of the charging induction coil is connected with the other end of the input end of the rectifier to form a receiving loop; the output end of the rectifier is connected with a battery load, and the inductive wireless constant-current charging is realized.

3. The wireless charging method with the transmission-side switching hybrid topology, constant current and constant voltage induction according to claim 1, wherein in step 2,

detecting the RMS value of the output current of the high-frequency inverter, comprising: acquiring instantaneous values of output currents of the high-frequency inverter through a current sensor and a controller in real time; calculating the root mean square value of the output current of the high-frequency inverter;

and the estimated charging voltage of the battery load is estimated according to the approximate linear function relation between the root mean square value of the output current of the high-frequency inverter and the charging voltage value of the battery in the constant-current charging process.

4. The wireless charging method of claim 1, wherein in step 4,

the constant voltage charging loop comprises a parallel constant voltage charging loop and a series constant voltage charging loop; the parallel constant voltage charging loop is composed of a primary constant voltage compensation capacitor C _R And a change-over switch S ₁ Series, T-connection and primary series compensation inductance L _R And a primary constant current compensation capacitor C _PA And the other end of the high-frequency inverter H; and switch S is switched ₁ The control end of the controller K is connected with the controller K; the series constant voltage charging loop is composed of a primary constant voltage compensation capacitor C _PB And a change-over switch S ₂ Connected in series and in parallel with a primary constant current compensation capacitor C _PA Upper and switch S ₂ The control end of the controller K is connected with the controller K;

the automatic switching to the constant voltage charging circuit is that when the preset root mean square value of the output current of the high-frequency inverter H meets the formula (1), the controller connects the parallel constant voltage charging circuit with the series constant voltage charging circuit, namely: closing the change-over switch S ₁ And S ₂ And the conversion of the battery load from a constant-current charging process to a constant-voltage charging process is realized.

5. The wireless charging method of claim 1, wherein, in step 6, when it is detected that the battery management system is disconnected or the battery load is fully charged, the constant voltage charging loop is disconnected, the inverter power supply output is automatically disconnected, and the charging is stopped (6);

the disconnected constant voltage charging circuit is a disconnected parallel constant voltage charging circuit and a serial constant voltage charging circuit, namely: switch off change-over switch S ₁ And S ₂ ；

In the automatic charging stopping process, when the preset root mean square value of the output current of the high-frequency inverter H meets the formula (3), the controller stops the power supply output of the inverter, namely: the charging is stopped.

6. A transmitting side switching hybrid topology constant-current constant-voltage induction type wireless charging system is characterized by comprising a direct-current power supply, a high-frequency inverter, a transmitting unit, a charging induction coil, a receiving unit, a current sensor, a controller, a rectifier and a battery load, wherein the charging induction coil is connected with the receiving unit,

the high-frequency inverter inverts and outputs an input direct-current power supply into a high-frequency alternating-current power supply, high-frequency alternating-current electric energy is wirelessly inductively coupled and transmitted to the receiving unit through the transmitting unit and the charging induction coil, and the high-frequency alternating-current electric energy is converted into direct current through the rectifier to charge a battery load with constant current; the current sensor and the controller detect the root mean square value of the output current of the high-frequency inverter in real time, the charging voltage of a battery load is estimated, and when the root mean square value of the output current of the high-frequency inverter meets the formula (1), the controller connects the parallel constant-voltage charging circuit and the series constant-voltage charging circuit, namely: closing the change-over switch S ₁ And S ₂ The conversion of the battery load from a constant-current charging process to a constant-voltage charging process is realized; when the root mean square value of the output current of the high-frequency inverter meets the formula (3), the constant-voltage charging loop is disconnected, the power supply output of the inverter is automatically disconnected, and the charging of the battery load is stopped;

the sending unit comprises a constant-current charging circuit, a parallel constant-voltage charging circuit and a series constant-voltage charging circuit; the receiving unit comprises a receiving loop, a rectifier D and an equivalent internal resistor R which are connected in sequence _B And an ideal voltage source U _B A battery load connected in series;

the charging induction coil comprises a sending side winding with a self-inductance parameter of L _P A resistance parameter of R _P And the self-inductance parameter of the receiving side winding is L _S The resistance parameter is R _S The mutual inductance parameter M of the charging induction coil is determined by the formula (4);

in the formula I _B For a set constant charging current, ω is the resonant angular frequency;

the constant current charging loop is composed of a primary series compensation inductor L _R And a primary constant current compensation capacitor C _PA Is formed by connecting in series, the head and the tail are respectively connected with one end of the output of the high-frequency inverter and the charging induction coil transmitting side winding L _P One end of (1), a charging induction coil transmitting side winding L _P The other end of the first and second switches is connected with the other end of the output of the high-frequency inverter；

The primary series compensation inductor L _R Represented by formula (5);

in the formula of U _B Is a set constant charging voltage;

the primary compensation capacitor C _PA Represented by formula (6);

the series constant voltage charging circuit is composed of a primary constant voltage compensation capacitor C _PB And a change-over switch S ₂ Are connected in series; is connected in parallel with a primary constant current compensation capacitor C _PA The above step (1); primary constant current compensation capacitor C _PA One end is connected with a primary series compensation inductor L _R The other end is connected with a transmitting side winding L of the charging induction coil _P (ii) a Charging induction coil transmitting side winding L _P The other end of the high-frequency inverter is connected with the other end of the output of the high-frequency inverter; and switch S is switched ₂ The control end of the controller K is connected with the controller K;

the primary constant voltage compensation capacitor C _PB Represented by formula (7);

the parallel constant voltage charging circuit is composed of a primary constant voltage compensation capacitor C _R And a change-over switch S ₁ Are connected in series; primary series compensation inductance L with one end connected in T shape _R And a primary constant current compensation capacitor C _PA The other end of the connection point of (b) is connected to the other end of the high-frequency inverter H and the charging induction coil transmitting side winding L _P The other end of (a); and switch S is switched ₁ The control end of the controller K is connected with the controller K;

the primary constant voltage compensation capacitor C _R Is represented by formula (8)；

The receiving loop is composed of a secondary compensation capacitor C _S The self-inductance parameter with the receiving side winding of the charging induction coil is L _S The resistance parameter is R _S After being connected in series, the input end of the rectifier is connected in parallel;

the secondary compensation capacitor C _S Represented by formula (9);

7. the wireless charging system of claim 6, wherein the wireless charging system comprises: current sensor and controller cooperation control change over switch S ₁ And a change-over switch S ₂ The switching on and off of the charging system realizes the conversion between the constant-current charging process and the constant-voltage charging process and the control of the charging end;

the change-over switch S ₁ And a change-over switch S ₂ The trigger control circuit is composed of a power electronic switching device and a trigger control driving circuit;

the current sensor does not distort when detecting MHz-level high-frequency current output by the high-frequency inverter;

the controller comprises an analog quantity input circuit, an analog-to-digital conversion circuit, an electro-physical quantity calculation program, a detection and control program, a switching value output circuit and an interface circuit for isolating and triggering a control drive circuit.

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