CN106961221A - Wireless power transmission with constant current output characteristic LC/S compensation topology circuits - Google Patents

Abstract

Wireless power transmission with constant current output characteristic LC/S compensation topology circuits, are related to wireless power transmission technical field.If the present invention is to think the peak power output of change system, it is necessary to remake loosely coupled transformer or increase compensating element, number, the problem of taking time and effort, efficiency is low, and add loss to solve already present wireless power transmission compensation topology.Direct voltage source positive pole connects the common interlink point of bridge arm on H bridges, and direct voltage source negative pole connects the common interlink point of bridge arm under H bridges, L₁Left end and C₁Lower end is connected across the upper and lower bridge arm midpoint of H bridges, L respectively₁Right-hand member and C₁Lower end is connected across primary side coupling coil two ends respectively, resistive load two ends connect with the common interlink point of diode rectifier bridge upper and lower bridge arm respectively, shunt capacitance wave filter is in parallel with resistive load, secondary coil two ends connect bridge arm midpoint on secondary compensating electric capacity left end and rectifier bridge respectively, and secondary compensating electric capacity right-hand member connects bridge arm midpoint on rectifier bridge.It is used in wireless power transmission.

Description

LC/S compensation topology circuit for wireless power transmission with constant current output characteristics

technical field

The invention relates to an LC/S compensation topology circuit for wireless power transmission with constant current output characteristics, and belongs to the technical field of wireless power transmission.

Background technique

Compared with the traditional cable power transmission method, wireless power transmission, as a new power transmission method, has very obvious advantages, such as more convenient, safe and reliable, and not affected by external weather conditions. Therefore, wireless power transmission Technology has been widely used in various fields. Appropriate compensation topology can effectively reduce the power level of the power supply, improve the power factor of the system, and obtain good output characteristics at the same time, but the existing compensation topology has the following problems:

1. The maximum output power of the system is limited by the parameters of the loosely coupled transformer

In some current compensation topologies for wireless power transmission, such as SS, SP, PS, PP, and S/SP compensation topologies, the maximum output power of the system is directly related to the parameters of the loosely coupled transformer. As long as the parameters of the loosely coupled transformer are determined, the maximum output power of the system is determined. . If you want to change the maximum output power of the system, you need to remake the loosely coupled transformer, but making a loosely coupled transformer that meets the requirements requires a lot of time and manpower, and the cost is too high and the efficiency is low.

2. The compensation model is too idealized and unrealistic

Theoretical analysis under ideal conditions shows that the performance indicators such as the output characteristics of the bilateral LCL compensation topology meet the requirements, but in practical applications, the bilateral LCL compensation topology does not meet the requirements, the main reason is that the compensation model is too ideal.

3. The number of compensation components is too large, the system cost is high, the size is large, and the loss is large

The output characteristics and other performance indicators of the bilateral LCC compensation topology meet the requirements, but the bilateral LCC compensation topology requires 6 compensation components (4 compensation capacitors, 2 compensation inductors), resulting in an increase in system cost, size and loss.

Contents of the invention

The purpose of the present invention is to solve the problem that if the existing wireless power transmission compensation topology wants to change the maximum output power of the system, it is necessary to remake the loose coupling transformer or increase the number of compensation components, which is time-consuming, labor-intensive, inefficient, and increases the loss. An LC/S compensation topology circuit for wireless power transmission with constant current output characteristics is now provided.

LC/S compensation topology circuit for wireless power transmission with constant current output characteristics, which includes a primary side power supply circuit and a secondary side load circuit,

The primary side power supply circuit includes a DC voltage source U _in , a full bridge inverter, an LC compensation circuit and a primary side coupling coil L _P of a loosely coupled transformer. The LC compensation circuit includes a primary side compensation inductor L ₁ and a primary side compensation capacitor C ₁ ,

The positive pole of the DC voltage source U _in is connected to the common connection node of the two upper bridge arms of the full-bridge inverter, and the negative pole of the DC voltage source U _in is connected to the common connection node of the two lower bridge arms of the full-bridge inverter.

One end of the primary side compensation inductor L ₁ is connected to the midpoint of one upper and lower bridge arm of the full-bridge inverter, and one end of the primary side compensation capacitor C ₁ is simultaneously connected to the middle point of the other upper and lower bridge arms of the full-bridge inverter Point and _one end of the primary side coupling coil L _P of the loosely coupled transformer, and the other end of the primary side compensation inductance L1 is simultaneously connected with the other end of the primary side compensation capacitor _C1 and the other end of the primary side coupling coil L _P of the loosely coupled transformer,

The secondary load circuit includes the secondary coupling coil L _S of the loosely coupled transformer, the secondary compensation capacitor C ₂ , the diode full-wave rectifier bridge, the shunt capacitor filter C _F and the resistive load R _L ,

One end of the secondary coupling coil L _S of the loosely coupled transformer is connected to one end of the secondary compensation capacitor _C2 , and the other end of the secondary compensation capacitor _C2 is connected to the midpoint of an upper and lower bridge arm of the diode full-wave rectifier bridge, loosely coupled The other end of the secondary coupling coil L _S of the transformer is connected to the midpoint of the other upper and lower bridge arms of the diode full-wave rectifier bridge, and one end of the parallel capacitor filter C _F is connected to the two upper bridge arms of the diode full-wave rectifier bridge The common connection node, the other end of the parallel capacitor filter C _F is connected to the common connection node of the two lower bridge arms of the diode full-wave rectifier bridge, and the resistive load R _L is connected in parallel at both ends of the capacitor filter C _F.

The beneficial effects of the present invention are:

The LC/S compensation topology circuit for wireless power transmission with constant current output characteristics of the present application has the following three beneficial effects:

(1) With LC/S compensation topology, the maximum output power of the system is not limited by the parameters of the loosely coupled transformer, and the maximum output power of the system can be changed without replacing the loosely coupled transformer, thereby saving time and manpower, reducing costs, and improving purpose of efficiency.

(2) The LC/S compensation topology has good constant current output characteristics, and the design of the system control circuit is greatly simplified, which indirectly improves system reliability and reduces system cost.

(3) Changing the series compensation capacitor in the load circuit will change the input impedance angle of the LC/S compensation topology. This compensation topology is easy to realize ZVS soft switching (zero voltage switching), the soft switching parameter design is simple, and the circuit debugging is easy; the system Lower loss and higher efficiency.

Description of drawings

1 is a circuit diagram of the LC/S compensation topology for wireless power transmission with constant current output characteristics described in Embodiment 1;

Fig. 2 is the circuit diagram of LC/S compensation topology analysis;

Fig. 3 is the circuit diagram of the mutual inductance model in the specific embodiment two;

Figure 4 is the voltage and current waveforms output by the full-bridge inverter during ZVS soft switching;

Fig. 5 is a voltage and current waveform diagram output by the full-bridge inverter when the zero phase angle is input;

Figure 6 is a load current waveform diagram during the load change process;

Fig. 7 is a relationship diagram of output power varying with input voltage and compensation parameters.

detailed description

Specific Embodiment 1: This embodiment is described in detail with reference to FIG. 1. The LC/S compensation topology circuit for wireless power transmission with constant current output characteristics described in this embodiment includes a primary power supply circuit and a secondary load circuit.

The primary side power supply circuit includes a DC voltage source U _in , a full bridge inverter, an LC compensation circuit and a primary side coupling coil L _P of a loosely coupled transformer. The LC compensation circuit includes a primary side compensation inductor L ₁ and a primary side compensation capacitor C ₁ ,

The positive pole of the DC voltage source U _in is connected to the common connection node of the two upper bridge arms of the full-bridge inverter, and the negative pole of the DC voltage source U _in is connected to the common connection node of the two lower bridge arms of the full-bridge inverter.

One end of the primary side compensation inductor L ₁ is connected to the midpoint of one upper and lower bridge arm of the full-bridge inverter, and one end of the primary side compensation capacitor C ₁ is simultaneously connected to the middle point of the other upper and lower bridge arms of the full-bridge inverter Point and _one end of the primary side coupling coil L _P of the loosely coupled transformer, and the other end of the primary side compensation inductance L1 is simultaneously connected with the other end of the primary side compensation capacitor _C1 and the other end of the primary side coupling coil L _P of the loosely coupled transformer,

The secondary load circuit includes the secondary coupling coil L _S of the loosely coupled transformer, the secondary compensation capacitor C ₂ , the diode full-wave rectifier bridge, the shunt capacitor filter C _F and the resistive load R _L ,

One end of the secondary coupling coil L _S of the loosely coupled transformer is connected to one end of the secondary compensation capacitor _C2 , and the other end of the secondary compensation capacitor _C2 is connected to the midpoint of an upper and lower bridge arm of the diode full-wave rectifier bridge, loosely coupled The other end of the secondary coupling coil L _S of the transformer is connected to the midpoint of the other upper and lower bridge arms of the diode full-wave rectifier bridge, and one end of the parallel capacitor filter C _F is connected to the two upper bridge arms of the diode full-wave rectifier bridge The common connection node, the other end of the parallel capacitor filter C _F is connected to the common connection node of the two lower bridge arms of the diode full-wave rectifier bridge, and the resistive load R _L is connected in parallel at both ends of the capacitor filter C _F.

Example:

The known parameters of the system are shown in Table 1.

Table 1 Known parameters of the system

The operating frequency of the system is 85kHz, and the operating angular frequency of the system is 0.534×10 ⁵ rad/s. From formulas 1 to 3, the effective value of the fundamental wave of the system's equivalent AC voltage source U _AB , the system's equivalent resistance R _E , and the loosely coupled transformer The mutual inductance M is 90.03V, 32.42Ω and 102.57μH in turn. Then, according to Formulas 4 and 5, the primary side compensation inductance L ₁ and the primary side compensation capacitor C ₁ are calculated as 317.3 μH and 26.63 nF, respectively. Then find out C ₁ ' by formula 7, its value is 11.05nF. Finally, according to formula 6, the secondary side compensation capacitor C ₂ is calculated as 22.89nF. The undetermined parameters of the system are listed in Table 2.

Table 2 Undetermined parameters of the system

Build a prototype according to the above parameters. Figure 4 is the output voltage and current waveforms of the full-bridge inverter during ZVS soft switching. It can be seen from Figure 4 that the voltage leads the current by about 30°. Increase the value of the secondary side compensation capacitor from 22.89nF to 29.09nF (according to formula 6 when the lead angle is 0°), the output voltage and current waveforms of the full-bridge inverter are shown in Figure 5, and the lead angle is significantly reduced. It is close to 0°, indicating that the input impedance angle of the LC/S compensation topology is easy to adjust, and ZVS soft switching is easy to implement. Figure 6 is the load current waveform diagram during the load change process. The load is 40Ω at the beginning, and the output current is 1.04A at this time, and then the load suddenly drops to 24.4Ω, and the load current suddenly drops to 1.7A, and then gradually decreases. After about 100ms It is stable at 1.04A. Although the load is reduced by 39%, the load current has no change, which shows the excellent constant current output characteristics of the LC/S compensation topology. Figure 7 shows the relationship between the system output power and the input voltage and compensation parameters. The reference number 1 corresponds to the compensation parameters (L ₁ , C ₁ and C ₂ ) in Table 2, and the compensation parameter corresponding to the reference number 2 is L ₁ =201.3 μH, C ₁ =33.35nF, C ₂ =22.89nF, these two curves show that the wireless power transmission system using LC/S compensation topology can change the system output power only by changing the compensation parameter value without replacing the loose coupling transformer.

Specific embodiment 2: This embodiment will be described in detail with reference to Fig. 2 and Fig. 3. This embodiment is a further description of the LC/S compensation topology circuit for wireless power transmission with constant current output characteristics described in specific embodiment 1. This embodiment In the embodiment, the DC voltage source U _in and the full-bridge inverter are equivalent to the AC voltage source U _AB , and the diode full-wave rectifier bridge, the parallel capacitor filter C _F and the resistive load R _L are equivalent to the equivalent resistance R _E Instead, the loosely coupled transformer is replaced by a mutual inductance model, and the primary side compensation capacitor C ₁ is divided into capacitor C ₁ ' and capacitor C ₁ ", and capacitor C ₁ ' and capacitor C ₁ " are connected in parallel,

According to the formula:

Obtain the voltage (effective value) of the AC voltage source U _AB ,

Among them, U _in is the DC input voltage, and α is the phase shift angle;

According to the formula:

Obtain the resistance value of the equivalent resistance R _E ,

Among them, _RL is resistive load;

According to the formula:

Obtain the mutual inductance M of the loosely coupled transformer,

Among them, k is the coupling coefficient of the primary and secondary coils of the loosely coupled transformer, L _P is the self-inductance of the primary coupling coil, and L _S is the self-inductance of the secondary coupling coil.

In this embodiment, the LC/S compensation topology analysis circuit is shown in FIG. 2 . Using the fundamental wave analysis method to analyze the LC/S compensation topology function, the DC voltage source and the full-bridge inverter are equivalent to the AC voltage source U _AB , U _AB is the effective value, which can be obtained by formula 1. Capacitor filter and resistive load are replaced by equivalent resistance _RE , whose value can be obtained by formula 2. Loosely coupled transformers (L _P , L _S , k) are replaced by their mutual inductance models. In Figure 2, j is the imaginary number unit, ω is the operating angular frequency of the full-bridge inverter (hereinafter referred to as the operating angular frequency of the system), and M is the loose The mutual inductance of the coupling transformer can be obtained by formula 3. I _P and I _S are the primary and secondary coupling coil currents (effective values) respectively, and the current direction is shown in Figure 2.

In the primary side LC compensation circuit, a part C ₁ ' of the primary side compensation capacitor C ₁ resonates with the primary side compensation inductor L ₁ at the operating angular frequency of the system to achieve constant current output characteristics; the other part C ₁ of the primary side compensation capacitor C ₁ ” and the primary side coupling coil L _P of the loosely coupled transformer resonate at the operating angular frequency of the system to achieve constant voltage output characteristics; the output voltage of the CL resonant cavity is equal to -jωMI _S , so the primary side constant voltage output means the secondary side constant current output .

The secondary side series compensation capacitor is called a phase shift capacitor, and its main purpose is to adjust the input impedance angle of the system and realize ZVS soft switching (zero voltage switching).

Known parameters in Figure 1 include:

1) DC input voltage: U _in

2) Load current: I _RL

3) Load resistance: R _L

4) Primary and secondary self-inductance and coupling coefficients of loosely coupled transformers: L _P , L _S , k

5) Phase shift angle: α

6) Leading angle (the angle at which the fundamental wave of the output voltage of the full-bridge inverter leads the fundamental wave of the current): β

Parameters to be determined include:

1) System working (angular) frequency: f(ω)

2) Primary side compensation inductance value: L ₁

3) Primary side compensation capacitor value: C ₁

4) Secondary side compensation capacitor value: C ₂

5) Filter capacitor value: C _F .

Specific embodiment three: this embodiment is a further description of the LC/S compensation topology circuit for wireless power transmission with constant current output characteristics described in specific embodiment _one . In this embodiment, the calculation of the primary side compensation inductance L1 The formula is:

In the formula, I _RL is the load current, ω is the system operating angular frequency,

The calculation formula of the primary side compensation capacitor _C1 is:

The _formula for calculating the secondary side compensation capacitor C2 is:

In the formula, C ₁ ' is the capacitor that resonates with the primary side compensation inductance L ₁ , which can be obtained by formula 7, β is the lead angle,

In this embodiment, according to the wireless charging standard J2954 ^TM , the system operating frequency is selected as 85 kHz, and the corresponding system operating angular frequency is 0.534×10 ⁵ rad/s.

_CF mainly depends on the requirements of the load voltage ripple. Properly increase or decrease the value of the filter capacitor according to the load voltage ripple. When the system power is less than 1kW, the value is usually between 220 and 1000μF.

Claims (3)

1. the wireless power transmission LC/S compensation topology circuits with constant current output characteristic, it is characterised in that it includes primary side Power circuit and secondary load circuit,

Primary side power circuit includes direct voltage source U_in, full-bridge inverter, the primary side coupling of LC compensation circuits and loosely coupled transformer Zygonema circle L_P, LC compensation circuits include primary side compensation inductance L₁With primary side compensating electric capacity C₁,

Direct voltage source U_inThe upper bridge arm of positive pole connection full-bridge inverter two common interlink point, direct voltage source U_inNegative pole connect The common interlink point of two lower bridge arms of full-bridge inverter is connect,

Primary side compensation inductance L₁One end connection full-bridge inverter a upper and lower bridge arm midpoint, primary side compensating electric capacity C₁One End connects midpoint and the primary side coupling coil L of loosely coupled transformer of another upper and lower bridge arm of full-bridge inverter simultaneously_POne End, primary side compensation inductance L₁The other end connect primary side compensating electric capacity C simultaneously₁The other end and loosely coupled transformer primary side coupling Zygonema circle L_PThe other end,

Secondary load circuit includes the secondary coupling coil L of loosely coupled transformer_S, secondary compensating electric capacity C₂, diode full-wave rectification Bridge, shunt capacitance wave filter C_FWith resistive load R_L,

The secondary coupling coil L of loosely coupled transformer_SOne end connection secondary compensating electric capacity C₂One end, secondary compensating electric capacity C₂ The other end connection diode full-wave rectification bridge a upper and lower bridge arm midpoint, the secondary coupling coil of loosely coupled transformer L_SThe other end connection diode full-wave rectification bridge another upper and lower bridge arm midpoint, shunt capacitance wave filter C_FOne end connect Connect the common interlink point of two upper bridge arms of diode full-wave rectification bridge, shunt capacitance wave filter C_FThe other end connection diode it is complete The common interlink point of two lower bridge arms of ripple rectifier bridge, resistive load R_LIt is connected in parallel on capacitive filter C_FTwo ends.

2. the LC/S compensation topology circuits of the wireless power transmission with constant current output characteristic according to claim 1, its It is characterised by, by direct voltage source U_inAlternating-current voltage source U is equivalent to full-bridge inverter_AB, by diode full-wave rectification bridge, simultaneously Join capacitive filter C_FWith resistive load R_LUse equivalent resistance R_EInstead of loosely coupled transformer is replaced with mutual inductance coupling model, and primary side is mended Repay electric capacity C₁It is divided into electric capacity C₁' and electric capacity C₁", electric capacity C₁' and electric capacity C₁" be connected in parallel,

According to formula：

Obtain alternating-current voltage source U_ABVoltage,

Wherein, U_inFor DC input voitage, α is phase shifting angle；

According to formula：

Obtain equivalent resistance R_EResistance,

Wherein, R_LFor resistive load；

According to formula：

The mutual inductance M of loosely coupled transformer is obtained,

Wherein, k is the former and deputy sideline circle coefficient of coup of loosely coupled transformer, L_PFor primary side coupling coil self-induction, L_SCoupled for secondary Self-induction of loop.

3. the LC/S compensation topology circuits of the wireless power transmission with constant current output characteristic according to claim 2, its It is characterised by, primary side compensation inductance L₁Computing formula be：

In formula, I_RLFor load current, ω is work angular frequency,

Primary side compensating electric capacity C₁Computing formula be：

Secondary compensating electric capacity C₂Computing formula be：

In formula,β is advance angle.