CN107528359A - The induction type wireless charging system of charging pile can be shared - Google Patents

Abstract

The invention discloses an inductive wireless charging system that can share charging piles. The system is composed of a sending part and a receiving part. A constant current and constant voltage switching circuit 1 and a constant current and constant voltage switching circuit 2 can be set up in the receiving part to realize it together. The components are respectively: the secondary constant current compensation inductor is connected in series with the switching switch one, and the control terminal of the switching switch one is connected to the controller one; the composition of the constant current constant voltage switching circuit two is: the secondary constant voltage compensation inductor and the The switch two is connected in parallel, and the control terminal of the switch two is connected with the controller one. The invention can output constant current and constant voltage irrelevant to the load, and is suitable for multiple charging systems to share one inverter. Devices with different needs can share charging piles to improve the utilization rate of charging piles.

Description

Inductive wireless charging system that can share charging piles

technical field

The invention relates to an inductive wireless charging system capable of sharing charging piles.

Background technique

Inductive wireless power transfer technology is a new type of power supply technology that uses soft media such as magnetic fields to realize non-contact power transmission. It is widely used in medical, consumer electronics, water Power supply, electric vehicle charging and rail transit and other fields. Among them, the use of inductive wireless power transmission technology to wirelessly charge the battery avoids the disadvantages of contact sparks and plug aging in the traditional plug-in system, and has a great development prospect.

In order to achieve safe charging of the battery, prolong the service life of the battery and the number of charge and discharge times, it usually mainly includes two charging stages of constant current and constant voltage. That is, the constant current mode is used at the initial stage of charging, and the battery voltage increases rapidly; when the battery voltage reaches the charging set voltage, the constant voltage mode is used for charging, and the charging current gradually decreases until it reaches the charging cut-off current, and the charging is completed. That is, the inductive wireless charging system that charges the battery should be able to provide constant current and voltage.

There are various specifications of rechargeable batteries on the market today, and their charging current and voltage requirements are often different. Therefore, only the only matching charging pile can be used for one-to-one inductive wireless charging. The rate is very low, very inconvenient, and the cost is high.

The main composition and working process of the existing wireless charging system are as follows: the power frequency alternating current is rectified into direct current, the direct current is reversed into high frequency alternating current after passing through the inverter, and the high frequency alternating current is injected into the primary coil to generate a high frequency alternating magnetic field ; The secondary coil induces an induced electromotive force in the high-frequency magnetic field generated by the primary coil, and the induced electromotive force provides electric energy to the load after high-frequency rectification. Since the equivalent impedance of the load (battery) changes, it is difficult for the system to output the constant current or voltage required by the load under a certain input voltage. In order to solve this problem, there are usually two methods: 1. Introduce closed-loop negative feedback control in the circuit system, such as adding a controller before the inverter to adjust the input voltage or adopting phase-shift control, or adding a negative feedback control after the secondary coil rectification DC-DC converter; its disadvantage is that it increases the control cost and complexity, and reduces the system stability. 2. Using frequency conversion control, the system works at two different frequency points to achieve constant current and constant voltage output, but this method will cause frequency bifurcation, resulting in unstable system operation.

Contents of the invention

The purpose of the present invention is to enable the inductive wireless charging system to output both constant current and constant voltage, which is suitable for charging batteries, especially for charging multiple loads under a single power source, such as charging multiple electric vehicles at the same time; and The control is convenient, the system works stably, and the input reactive power is almost zero; only by changing the secondary parameters, the output voltage and current of different requirements can be configured, so that batteries requiring different charging currents and voltages can share the charging pile, improving the utilization rate of the charging pile .

The technical solution adopted by the present invention to achieve the purpose of the invention is an inductive wireless charging system that can share charging piles, which is composed of a sending part and a receiving part. The input end of the high-frequency inverter H is connected to the DC power supply E, and the high-frequency The output terminal of the inverter H is connected in series with the primary compensation capacitor C _P to form the sending part; the receiving part is composed of: the secondary coil L _S , the secondary compensator _{P e1} Compensator 2 P _e2 , secondary compensation capacitor 2 C _S3 , constant current and constant voltage switching circuit 2 Q ₂ , and rectification filter circuit D are connected sequentially; secondary compensation capacitor 1 C _S1 is connected to secondary compensator 1 P _e1 and secondary Between the connection point of the compensator 2 P _e2 and the connection point of the secondary coil L _S and the rectification filter circuit D; the output terminal of the rectification filter circuit D is connected to the battery load Z. A constant current and constant voltage switching circuit Q1 is connected between the connection point _of the secondary compensator two P _e2 and the secondary compensation capacitor C _S3 and the connection point between the secondary compensation capacitor C _S1 and the rectification filter circuit D. A constant current and constant voltage switching circuit Q ₂ is connected in series between the secondary compensation capacitor C _S3 and the rectification filter circuit D.

The composition of the constant current and constant voltage switching circuit _- Q1 is: the secondary constant-current compensation inductor L _S3 is connected in series with the switch _- S1, and the control terminal _of the switch-S1 is connected to the controller _- K1.

The composition of the constant current and constant voltage switching circuit 2 Q ₂ is: the secondary constant voltage compensation inductance L _V is connected in parallel with the switch 2 S ₂ , and the control terminal of the switch 2 S ₂ is connected to the controller 1 K ₁ .

Further, the first secondary compensator P _e1 and the second secondary compensator P _e2 are composed of inductors or capacitors. Secondary compensator 1 P _e1 and secondary compensator 2 P _e2 are composed of inductance or capacitance, and there are four situations: P _e1 inductance-P _e2 inductance, P _e1 inductance-P _e2 capacitance, P _e1 capacitance-P _e2 inductance, P _e1 capacitance - P _e2 capacitance.

Further, the capacitance value of the primary compensation capacitor C _P Determined by formula (1):

Where ω is the operating angular frequency of the system.

The capacitance value of the secondary compensation capacitor C _S1 Determined by formula (2):

in is the output voltage value of the DC power supply E, _M is the mutual inductance value of the primary coil _LP and the secondary coil LS, and V _B is the set charging voltage.

The capacitance value of the secondary compensation capacitor C _S3 Determined by formula (3):

Where I _B is the set charging current.

The inductance value of the secondary constant current compensation inductor L _S3 Determined by formula (4):

The inductance value of the secondary CV compensation inductor L _V Determined by formula (5):

Described secondary compensator-P _e1 is determined by the following formula: if the impedance of secondary compensator-P _e1 Inductive, it is composed of secondary coil compensation inductance L _e1 , its value Determined by formula (6):

If the impedance of the secondary compensator a P _e1 If it is capacitive, it is composed of the secondary coil compensation capacitor C _e1 , whose value Determined by formula (7):

The secondary compensator two P _e2 is determined by the following formula: if the impedance of the secondary compensator two P _e2 Inductive, it is composed of secondary coil compensation inductance L _e2 , its value Determined by formula (8):

If the impedance of the secondary compensator-P _e2 If it is capacitive, it is composed of the secondary coil compensation capacitor C _e2 , and its value Determined by formula (9):

The using method of technical scheme of the present invention is:

Controller 1 controls switch 1 to close and switch 2 to close, the system works in constant current mode and outputs a constant current to the load, that is, provides a set constant charging current I _B to the battery; it is suitable for the initial stage of battery charging.

Controller 1 controls switch 1 to turn off and switch 2 to turn off, the system works in constant voltage mode and outputs a constant voltage to the load, that is, provides the battery with a set constant charging voltage V _B ; it is suitable for the late stage of battery charging, battery voltage It is used when the charging set voltage is reached.

The theoretical analysis of system output constant current and constant voltage in the scheme of the present invention is as follows:

Consider the circuit shown in Figure 1, where the primary coil is L _P and the secondary coil is L _S . Its T-type equivalent circuit is shown in Figure 2, where the excitation inductance L=M, the primary and secondary leakage inductances are: L _P -M, L _S -M respectively, if C _P satisfies C _S satisfies which is

When , the system input impedance is:

Further, the output current can be calculated as:

It can be concluded that under the structure of Figure 1, the input impedance of the system is purely resistive, and the output current of the system has nothing to do with the size of the load, that is, the system can maintain a constant current output under the condition of load fluctuation, which is suitable for battery charging early stage.

Similarly, considering the structure shown in Figure 3, if L _S1 and L _S2 respectively satisfy the relationship:

Then the system input impedance is:

Further, the output voltage can be calculated as:

It can be concluded that under the structure of Figure 3, the input impedance of the system is purely resistive, and the output voltage of the system has nothing to do with the size of the load, that is, the system can maintain a constant voltage output under the condition of load changes, which is suitable for battery charging late period.

Similarly, consider the structure shown in Figure 4, if C _S2 and C _S3 respectively satisfy the relationship:

Then the system input impedance is:

Further, the output current can be calculated as:

It can be concluded that under the structure of Figure 4, the input impedance of the system is purely resistive, and the output current of the system has nothing to do with the size of the load, that is, the system can maintain a constant current output under the condition of load fluctuation, which is suitable for battery charging early stage.

If the voltage source in Figure 1 is replaced by a DC power supply E and a high-frequency inverter, the input voltage of the high-frequency inverter The relationship between and the output voltage V _i is:

The current source in Figure 3 is replaced by the system output current in Figure 1, the voltage source in Figure 4 is replaced by the system output voltage in Figure 3, the load in Figure 4 is replaced by a battery load and a rectifier bridge, and the input voltage of the rectifier bridge The relationship between V _o and the output voltage V _B is:

The relationship between the input current I _o and the output current I _B of the rectifier bridge is:

Then it can be combined into the structure shown in Figure 5. Based on the analysis done above, it is obvious that the system input impedance is purely resistive under such a structure, and the functions of voltage source input and system constant current output can be realized. The combined formula (12 ), (15), (18), (19), (21) can obtain the output current as:

Suitable for the early stage of battery charging. In order to reduce components and save cost, C _S and L _S1 in the structure shown in Figure 5 are combined into a component secondary compensator P _e1 , and L _S2 and C _S2 are combined into a component secondary compensator P _e2 , to get the structure shown in Figure 6.

The circuit implementation principle of the system constant current output is introduced above, and the following will introduce the conversion between the system constant voltage and constant current output through the secondary variable structure on the basis of the structure shown in Figure 6, so as to meet the requirements of the system during the entire charging process. output voltage and current requirements.

The scheme is shown in Figure 7,

In the early stage of charging, in order to obtain a constant current output of the system, controller one K ₁ closes switch one S ₁ and switches two S ₂ , and the system structure becomes that shown in Fig. 6 .

In the later stage of charging, in order to obtain a constant voltage output of the system voltage, controller one K ₁ turns off switch one S ₁ and switch two _{S 2} , under this structure, when the secondary constant voltage compensation inductance L Impedance value of _V Satisfy

, based on the analysis done above, it is obvious that under such a structure, the input impedance of the system is purely resistive, and the function of voltage source input and system constant voltage output can be realized. Combined formulas (12), (15), (19) , (20) can obtain its output voltage as:

Then the load constant voltage V _B required by the user, the input DC voltage The inductance value of the primary coil L _P and the secondary coil L _S Under the condition of the mutual inductance M between the primary and secondary stages and the operating frequency f of the system, the capacitance value of the secondary compensation capacitor C _S1 can be known from formula (24) Conditions to be met:

From formula (10), we can know the capacitance value of the primary compensation capacitor C _P Conditions to be met:

From formula (10), it can be known that the capacitance value of CS constituting the secondary compensator- _{P e1} Conditions to be met:

From equations (13) and (25), we can know the inductance value of L _S1 that constitutes the secondary compensator-P _e1 Conditions to be met:

The secondary compensator-P _e1 can be determined by equations (27) and (28): if the impedance of the secondary compensator-P _e1 Inductive, it is composed of secondary coil compensation inductance L _e1 , its value Determined by formula (29):

If the impedance of the secondary compensator a P _e1 If it is capacitive, it is composed of the secondary coil compensation capacitor C _e1 , whose value Determined by formula (30):

From the formula (13), it can be known that the inductance value of L _S2 that constitutes the secondary compensator 2 P _e2 Conditions to be met:

In order to determine the parameters of other components in the system in Fig. 7, controller one K ₁ closes switch one S ₁ and turns off switch two S ₂ to make the system output a constant current.

From equations (22) and (25), we can know the inductance value of the secondary constant current compensation inductor L _S3 Conditions to be met:

From equations (16) and (32), it can be known that the capacitance value of C _S2 constituting the secondary compensator 2 P _e2 Conditions to be met:

The second P _e2 of the secondary compensator can be determined by equations (31) and (33): If the impedance of the secondary compensator P _e2 Inductive, it is composed of secondary coil compensation inductance L _e2 , its value Determined by formula (34):

If the impedance of the secondary compensator-P _e2 If it is capacitive, it is composed of the secondary coil compensation capacitor C _e2 , and its value Determined by formula (35):

From equations (16) and (32), we can know the capacitance value of the secondary compensation capacitor C _S3 Conditions to be met:

Finally, from equations (23), (25), (35), and (36), we can know the inductance value of the secondary constant voltage compensation inductor L _V Conditions to be met:

To sum up, when controller one K ₁ closes switch one S ₁ and switches two S ₂ , the system outputs a constant current, which is suitable for use in the early stage of charging, and when controller one K ₁ turns off switch one S _1. Turn off the switch 2 S ₂ , then the system will output a constant voltage, which is suitable for use in the later stage of charging.

Combining formulas (22) and (24), it can be concluded that when working in constant current output mode or constant voltage output mode, the output current or output voltage can be changed only by changing the secondary parameters, so the requirements for charging current and charging voltage are different When charging the equipment, the charging pile of the same specification can be used, which improves the compatibility of the charging pile, is more convenient, and reduces the manufacturing cost.

In addition, the combined formulas (11), (14), and (17) can be deduced to work in the constant current output mode, the input impedance of the system is: It is purely resistive, so when the system outputs constant current, the system has almost no reactive power input, which reduces the system's requirements for inverter capacity.

Similarly, the combined formula (11) and (14) can be deduced to work in the constant voltage output mode, the input impedance of the system is: It is purely resistive, so when the system outputs constant current, the system has almost no reactive power input, which reduces the system's requirements for inverter capacity.

Compared with prior art, the beneficial effect of the present invention is:

1. An inductive wireless charging system that can share charging piles proposed by the present invention can change the circuit topology of the secondary only by setting two switches on the secondary, so that it can output constant current and load-independent Constant voltage, which meets the requirements of constant current charging in the initial stage and constant voltage charging in the later stage of the battery. The system works at one frequency point, there will be no frequency bifurcation phenomenon, and the system works stably. Its circuit structure is simple, the cost is low, and it only needs simple switching of the control switch during operation, without complex control strategies, and without primary and secondary communication; its control is simple, convenient and reliable.

2. After the circuit parameters of the system are determined, the output constant current and constant voltage that have nothing to do with the load are only related to the output voltage of the high-frequency inverter, so multiple high-frequency inverter rear circuits of this type of system can be connected in parallel to the On the same high-frequency inverter, multiple batteries or charging devices can be charged at the same time, which greatly reduces the number of high-frequency inverters when charging multiple battery loads, and reduces charging costs.

3. In the circuit topology of the present invention, when the system outputs constant voltage and constant current, the inverter output voltage and current are in the same phase, so that the inverter hardly injects reactive power, so the system loss is small, and the capacity of the inverter is relatively small. Lower requirements.

4. The circuit topology of the present invention can be changed only by changing the secondary parameters when the system outputs constant voltage or constant current, so when charging devices with different charging current and charging voltage requirements, it can be used Charging piles of the same specification increase the utilization rate of charging piles, are more convenient, and reduce manufacturing costs.

The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments.

Description of drawings

Figure 1 is a system circuit diagram of both the primary and secondary stages of series compensation.

Fig. 2 is a T-type equivalent circuit diagram of a system circuit in which both primary and secondary stages are series compensated.

Fig. 3 is the circuit diagram of the LCL type whose excitation source is a current source.

Fig. 4 is a CLC circuit diagram in which the excitation source is a voltage source.

Figure 5 is a circuit diagram of the constant current output system.

Figure 6 is a simplified diagram of the circuit diagram of the constant current output system.

Fig. 7 is a system circuit diagram.

Explanation of the symbols in the figure: E is the DC power supply, H is the high-frequency inverter, Q1 is the _first constant current and constant voltage switching circuit, Q2 is the _second constant current and constant voltage switching circuit, C _P is the primary compensation capacitor, L _P is the Primary coil, L _S is the secondary coil, P _e1 is the secondary compensator 1, P _e2 is the secondary compensator 2, C _S1 is the secondary compensation capacitor 1, C _S3 is the secondary compensation capacitor 2, L _S3 is the secondary Level constant current compensation inductance, L _V is the secondary constant voltage compensation inductance, D is the rectification filter circuit, Z is the battery load, S ₁ is the switch one, S ₂ is the switch two, K ₁ is the controller one, V _i is the equivalent output voltage of the high-frequency inverter H, R is the battery equivalent load seen from the input port of the rectification filter circuit, V _B is the voltage at both ends of the battery, and I _B is the current flowing through the battery.

detailed description

As shown in Figure 7, the specific embodiment of the present invention is an inductive wireless charging system that can share charging piles, which consists of a sending part and a receiving part. The input end of the high-frequency inverter H is connected to the DC power supply E, and the high The output terminal of the inverter H is connected in series with the primary compensation capacitor C _P to form the sending part; the receiving part is composed of: the secondary coil L _S , the secondary compensator _{P e1} The second compensator P _e2 , the second secondary compensation capacitor C _S3 , the second constant current and constant voltage switching circuit Q ₂ , and the rectification and filtering circuit D are sequentially connected; the first secondary compensator P _e1 and the second secondary compensator P _e2 are composed of Composed of inductance or capacitance; the secondary compensation capacitor C _S1 is connected between the connection point of the secondary compensator P _e1 and the secondary compensator P _e2 and the connection point between the secondary coil L _S and the rectification filter circuit D; the rectification filter circuit The output terminal of D is connected to the battery load Z.

A constant current and constant voltage switching circuit Q1 is connected between the connection point _of the secondary compensator two P _e2 and the secondary compensation capacitor C _S3 and the connection point between the secondary compensation capacitor C _S1 and the rectification filter circuit D. A constant current and constant voltage switching circuit Q ₂ is connected in series between the secondary compensation capacitor C _S3 and the rectification filter circuit D.

The composition of the constant current and constant voltage switching circuit _- Q1 is: the secondary constant-current compensation inductor L _S3 is connected in series with the switch _- S1, and the control terminal _of the switch-S1 is connected to the controller _- K1.

The composition of the constant current and constant voltage switching circuit 2 Q ₂ is: the secondary constant voltage compensation inductance L _V is connected in parallel with the switch 2 S ₂ , and the control terminal of the switch 2 S ₂ is connected to the controller 1 K ₁ .

The capacitance value of the primary compensation capacitor C _P Determined by formula (1):

Where ω is the operating angular frequency of the system.

The capacitance value of the secondary compensation capacitor C _S1 Determined by formula (2):

in is the output voltage value of the DC power supply E, _M is the mutual inductance value of the primary coil _LP and the secondary coil LS, and V _B is the set charging voltage.

The capacitance value of the secondary compensation capacitor C _S3 Determined by formula (3):

Where I _B is the set charging current.

The inductance value of the secondary constant current compensation inductor L _S3 Determined by formula (4):

The inductance value of the secondary CV compensation inductor L _V Determined by formula (5):

Described secondary compensator-P _e1 is determined by the following formula: if the impedance of secondary compensator-P _e1 Inductive, it is composed of secondary coil compensation inductance L _e1 , its value Determined by formula (6):

If the impedance of the secondary compensator a P _e1 If it is capacitive, it is composed of the secondary coil compensation capacitor C _e1 , whose value Determined by formula (7):

The secondary compensator two P _e2 is determined by the following formula: if the impedance of the secondary compensator two P _e2 Inductive, it is composed of secondary coil compensation inductance L _e2 , its value Determined by formula (8):

If the impedance of the secondary compensator-P _e2 If it is capacitive, it is composed of the secondary coil compensation capacitor C _e2 , and its value Determined by formula (9):

.

Claims (6)

1. An inductive wireless charging system that can share charging piles, which consists of a sending part and a receiving part. The input end of the high-frequency inverter (H) is connected to the DC power supply (E), and the high-frequency inverter (H) The output terminal is connected in series with the primary compensation capacitor (C _P ) and connected to the primary _coil ( _{L P} ) to form the sending part; , Secondary Compensator (P _e2 ), Secondary Compensation Capacitor Two (C _S3 ), Constant Current and Constant Voltage Switching Circuit Two (Q ₂ ), Rectification and Filtering Circuit (D) are connected sequentially; Secondary Compensation Capacitor One (C _S1 ) is connected between the connection point of the secondary compensator one (P _e1 ) and the secondary compensator two (P _e2 ) and the connection point between the secondary coil (L _S ) and the rectification filter circuit (D); the rectification filter circuit (D) The output end is connected to the battery load (Z); it is characterized in that the connection point between the secondary compensator two (P _e2 ) and the secondary compensation capacitor two (C _S3 ) and the connection point between the secondary compensation capacitor one (C _S1 ) and the rectification filter A constant current and constant voltage switching circuit 1 (Q ₁ ) is connected between the connection points of the circuit (D), and a constant current and constant voltage switching circuit is connected in series between the secondary compensation capacitor 2 (C _S3 ) and the rectification and filtering circuit (D). Two (Q ₂ ); The composition of the constant current and constant voltage switching circuit one (Q ₁ ) is: the secondary constant current compensation inductance (L _S3 ) is connected in series with the switch one (S ₁ ), and the control terminal of the switch one (S ₁ ) is connected to Controller one (K ₁ ) is connected; The composition of the constant current and constant voltage switching circuit 2 (Q ₂ ) is: the secondary constant voltage compensation inductance (L _V ) is connected in parallel with the switching switch 2 (S ₂ ), and the control terminal of the switching switch 2 (S ₂ ) is connected to Controller one (K ₁ ) is connected. 2 . The inductive wireless charging system capable of sharing charging piles according to claim 1 , wherein the first secondary compensator ( P _e1 ) and the second secondary compensator ( P _e2 ) are composed of inductors. 3 . 3. The inductive wireless charging system capable of sharing charging piles according to claim 1, wherein said secondary compensator one (P _e1 ) and secondary compensator two (P _e2 ) are composed of capacitors. 4. The inductive wireless charging system capable of sharing charging piles according to claim 1, wherein the secondary compensator one (P _e1 ) is composed of an inductor; the secondary compensator two (P _e2 ) is composed of Capacitor composition. 5. The inductive wireless charging system capable of sharing charging piles according to claim 1, wherein the secondary compensator one (P _e1 ) is composed of a capacitor and an inductance; the secondary compensator two (P e1 _e2 ) consists of inductance. 6. The inductive wireless charging system capable of sharing charging piles according to claim 1, characterized in that: The capacitance value of the primary compensation capacitor (C _P ) Determined by formula (1): <mrow><mover><msub><mi>C</mi><mi>P</mi></msub><mo>&amp;OverBar;</mo></mover><mo>=</mo><mfrac><mn>1</mn><mrow><msup><mi>&amp;omega;</mi><mn>2</mn></msup><mover><msub><mi>L</mi><mi>P</mi></msub><mo>&amp;OverBar;</mo></mover></mrow></mfrac><mo>-</mo><mo>-</mo><mo>-</mo><mrow><mo>(</mo><mn>1</mn><mo>)</mo></mrow></mrow> Where ω is the operating angular frequency of the system; The capacitance value of the secondary compensation capacitor one (C _S1 ) Determined by formula (2): <mrow><mover><msub><mi>C</mi><mrow><mi>S</mi><mn>1</mn></mrow></msub><mo>&amp;OverBar;</mo></mover><mo>=</mo><mfrac><mover><mi>E</mi><mo>&amp;OverBar;</mo></mover><mrow><msup><mi>&amp;omega;</mi><mn>2</mn></msup><msub><mi>MV</mi><mi>B</mi></msub></mrow></mfrac><mo>-</mo><mo>-</mo><mo>-</mo><mrow><mo>(</mo><mn>2</mn><mo>)</mo></mrow></mrow> in is the output voltage value of the DC power supply (E), M is the mutual inductance value between the primary coil (L _P ) and the secondary coil (L _S ), and V _B is the set charging voltage; The capacitance value of the secondary compensation capacitor 2 (C _S3 ) Determined by formula (3): <mrow><mover><msub><mi>C</mi><mrow><mi>S</mi><mn>3</mn></mrow></msub><mo>&amp;OverBar;</mo></mover><mo>=</mo><mfrac><mrow><msup><mi>&amp;pi;</mi><mn>2</mn></msup><msub><mi>I</mi><mi>B</mi></msub></mrow><mrow><mn>8</mn><msub><mi>&amp;omega;V</mi><mi>B</mi></msub></mrow></mfrac><mo>-</mo><mo>-</mo><mo>-</mo><mrow><mo>(</mo><mn>3</mn><mo>)</mo></mrow></mrow> Where I _B is the set charging current; The inductance value of the secondary constant current compensation inductor (L _S3 ) Determined by formula (4): <mrow><mover><msub><mi>L</mi><mrow><mi>S</mi><mn>3</mn></mrow></msub><mo>&amp;OverBar;</mo></mover><mo>=</mo><mfrac><mrow><mn>8</mn><msub><mi>V</mi><mi>B</mi></msub></mrow><mrow><msup><mi>&amp;pi;</mi><mn>2</mn></msup><msub><mi>&amp;omega;I</mi>mi><mi>B</mi></msub></mrow></mfrac><mo>-</mo><mo>-</mo><mo>-</mo><mrow><mo>(</mo><mn>4</mn><mo>)</mo></mrow></mrow> The inductance value of the secondary constant voltage compensation inductor (L _V ) Determined by formula (5): <mrow><mover><msub><mi>L</mi><mi>V</mi></msub><mo>&amp;OverBar;</mo></mover><mo>=</mo><mfrac><mrow><mn>16</mn><msub><mi>V</mi><mi>B</mi></msub></mrow><mrow><msup><mi>&amp;pi;</mi><mn>2</mn></msup><msub><mi>&amp;omega;I</mi><mi>B</mi></msub></mrow></mfrac><mo>-</mo><mo>-</mo><mo>-</mo><mrow><mo>(</mo><mn>5</mn><mo>)</mo></mrow></mrow> Described secondary compensator one (P _e1 ) is determined by the following formula: if the impedance of secondary compensator one P _e1 Inductive, it is composed of secondary coil compensation inductance L _e1 , its value Determined by formula (6): <mrow><mover><msub><mi>L</mi><mrow><mi>e</mi><mn>1</mn></mrow></msub><mo>&amp;OverBar;</mo></mover><mo>=</mo><mfrac><mrow><msub><mi>MV</mi><mi>B</mi></msub></mrow><mover><mi>E</mi><mo>&amp;OverBar;</mo></mover></mfrac><mo>-</mo><mover><msub><mi>L</mo>mi><mi>S</mi></msub><mo>&amp;OverBar;</mo></mover><mo>-</mo><mo>-</mo><mo>-</mo><mrow><mo>(</mo><mn>6</mn><mo>)</mo></mrow></mrow> If the impedance of the secondary compensator a P _e1 If it is capacitive, it is composed of the secondary coil compensation capacitor C _e1 , whose value Determined by formula (7): <mrow><mover><msub><mi>C</mi><mrow><mi>e</mi><mn>1</mn></mrow></msub><mo>&amp;OverBar;</mo></mover><mo>=</mo><mfrac><mover><mi>E</mi><mo>&amp;OverBar;</mo></mover><mrow><msup><mi>&amp;omega;</mi><mn>2</mn></msup><mrow><mo>(</mo><mover><mi>E</mi><mo>&amp;OverBar;</mo></mover><mover><msub><mi>L</mi><mi>S</mi></msub><mo>&amp;OverBar;</mo></mover><mo>-</mo><msub><mi>MV</mi><mi>B</mi></msub><mo>)</mo></mrow></mrow></mfrac><mo>-</mo><mo>-</mo><mo>-</mo><mrow><mo>(</mo><mn>7</mn><mo>)</mo></mrow></mrow> The secondary compensator two (P _e2 ) is determined by the following formula: if the impedance of the secondary compensator two P _e2 Inductive, it is composed of secondary coil compensation inductance L _e2 , its value Determined by formula (8): <mrow><mover><msub><mi>L</mi><mrow><mi>e</mi><mn>2</mn></mrow></msub><mo>&amp;OverBar;</mo></mover><mo>=</mo><mfrac><mrow><msub><mi>MV</mi><mi>B</mi></msub></mrow><mover><mi>E</mi><mo>&amp;OverBar;</mo></mover></mfrac><mo>-</mo><mfrac><mrow><mn>8</mn><msub><mi>V</mi><mi>B</mi></msub></mrow><mrow><msup><mi>&amp;pi;</mi><mn>2</mn></msup><msub><mi>&amp;omega;I</mi><mi>B</mi></msub></mrow></mfrac><mo>-</mo><mo>-</mo><mo>-</mo><mrow><mo>(</mo><mn>8</mn><mo>)</mo></mrow></mrow> If the impedance of the secondary compensator-P _e2 If it is capacitive, it is composed of the secondary coil compensation capacitor C _e2 , and its value Determined by formula (9): <mrow><mover><msub><mi>C</mi><mrow><mi>e</mi><mn>2</mn></mrow></msub><mo>&amp;OverBar;</mo></mover><mo>=</mo><mfrac><mrow><msup><mi>&amp;pi;</mi><mn>2</mn></msup><mover><mi>E</mi><mo>&amp;OverBar;</mo></mover><msub><mi>I</mi><mi>B</mi></msub></mrow><mrow><msub><mi>&amp;omega;V</mi><mi>B</mi></msub><mrow><mo>(</mo><mn>8</mn><mover><mi>E</mi><mo>&amp;OverBar;</mo></mover><mo>-</mo><msup><mi>&amp;pi;</mi><mn>2</mn></msup><msub><mi>&amp;omega;MI</mi><mi>B</mi></msub><mo>)</mo></mrow></mrow></mfrac><mo>-</mo><mo>-</mo><mo>-</mo><mrow><mo>(</mo><mn>9</mn><mo>)</mo></mrow><mo>.</mo></mrow>