A wireless charging system with anti-offset and phased constant current and constant voltage output

Abstract

The present invention provides a wireless charging system with anti-offset and phased constant current and constant voltage output. The wireless charging system includes a transmitting end and a receiving end. The transmitting end includes a high-frequency AC power supply, a transmitting-end compensation network, and a transmitting coil. The output port of the high-frequency AC power supply is connected to the input port of the transmitting-end compensation network, and the transmitting coil is connected to the output port of the transmitting-end compensation network. The receiving end includes a receiving coil, a receiving-end compensation network, a high-frequency rectifier filter, and a load. The receiving coil is connected to the input port of the receiving-end compensation network, the output port of the receiving-end compensation network is connected to the input port of the high-frequency rectifier filter, and the output port of the high-frequency rectifier filter is connected to the load. Both the transmitting-end compensation network and the receiving-end compensation network are series compensations. The present invention can adjust the charging voltage and current in real time according to the charging demand, realize phased constant current and constant voltage output, and achieve a fast and stable switch between the constant current mode and the constant voltage mode.

Description

Technical Field

[0001] The present invention relates to the technical field of wireless charging, and in particular to a wireless charging system with anti-offset and staged constant current and constant voltage output. Background Art

[0002] Wireless charging technology has the characteristics of convenience, safety and reliability, and has broad application prospects in medical treatment, portable communication, transportation and other aspects. Among the many application fields of wireless charging, wireless charging for electric vehicles is undoubtedly one of the most common application scenarios. At the same time, wireless charging technology can realize wireless transmission of electrical energy with a relatively long distance and high power from the ground to the vehicle chassis, which is an ideal solution to solve the problems of insufficient battery life and inconvenient charging of electric vehicles. The mainstream charging method for the power batteries of current electric vehicles is constant current and constant voltage charging, which requires the wireless charging system to have the ability of staged constant current and constant voltage output, and be able to perform a fast and stable switch between the constant current and constant voltage modes. However, the structure and parameters of the compensation network have an important impact on the output of the wireless charging system. When the compensation network is determined, the system also maintains a single output characteristic, which cannot meet the requirements of constant current and constant voltage charging of the power batteries of electric vehicles. In the prior art, the constant current and constant voltage charging requirements of wireless charging are often met by switching different types of compensation topologies or changing their compensation parameters by switching compensation components under a fixed compensation topology, adding switched capacitors, front-stage or rear-stage conversion circuits, constant current and constant voltage output self-switching circuits, etc. However, for the method starting from the system structure, topology switching or component switching requires adding redundant compensation components, and the switching operation at the transmitting end requires communication between the primary and secondary sides. The switching process may also cause instability of voltage and current. Moreover, if an additional conversion circuit is added, the overall efficiency of the system will be reduced, and the control complexity of the system will be increased. Summary of the Invention

[0003] The object of the present invention is to overcome the shortcomings in the prior art and provide a wireless charging system with anti-offset and staged constant current and constant voltage output.

[0004] The object of the present invention is achieved by the following technical solutions:

[0005] An anti-offset phased constant-current and constant-voltage output wireless charging system, comprising a transmitting end and a receiving end. The transmitting end includes a high-frequency AC power supply, a transmitting-end compensation network, and a transmitting coil. The output port of the high-frequency AC power supply is connected to the input port of the transmitting-end compensation network, and the transmitting coil is connected to the output port of the transmitting-end compensation network. The receiving end includes a receiving coil, a receiving-end compensation network, a high-frequency rectifier filter, and a load. The receiving coil is connected to the input port of the receiving-end compensation network, the output port of the receiving-end compensation network is connected to the input port of the high-frequency rectifier filter, and the output port of the high-frequency rectifier filter is connected to the load. Both the transmitting-end compensation network and the receiving-end compensation network are series compensations.

[0006] Furthermore, a transmitting-end control module is also connected between the high-frequency AC power supply and the transmitting-end compensation network. The transmitting-end control module includes a transmitting-end voltage detection unit, a transmitting-end current detection unit, an input impedance calculation unit, and a transmitting-end DSP (Digital Signal Process) chip. The transmitting-end current detection unit is connected in series between the output port of the high-frequency AC power supply and the input port of the transmitting-end compensation network. The transmitting-end voltage detection unit is connected in parallel between the output ports of the high-frequency AC power supply. The transmitting-end voltage detection unit and the transmitting-end current detection unit are also simultaneously connected to the input impedance calculation unit. The input impedance calculation unit is connected to the transmitting-end DSP chip, and the transmitting-end DSP chip is connected to the control port of the high-frequency AC power supply. The transmitting-end voltage detection unit is used to detect the voltage value output by the high-frequency AC power supply, the transmitting-end current detection unit is used to detect the current value output by the high-frequency AC power supply, the input impedance calculation unit is used to calculate the phase angle of the input impedance based on the detected voltage value and current value, and the transmitting-end DSP chip is used to control and adjust the output voltage value of the high-frequency AC power supply according to the calculated phase angle of the input impedance.

[0007] Furthermore, a transmitting-end drive circuit is also connected between the transmitting-end DSP chip and the high-frequency AC power supply. The transmitting-end DSP chip adjusts the output voltage of the high-frequency AC power supply through the transmitting-end drive circuit.

[0008] Furthermore, the receiving-end compensation network includes capacitor C s1 、capacitor C s2 and a bidirectional switch S. One end of capacitor C s1 is connected to the receiving coil, and the other end is connected to one end of capacitor C s2 . The other end of capacitor C s2 is connected to the high-frequency rectifier filter, and the bidirectional switch S is connected in parallel across capacitor C s2 .

[0009] Further, a receiving - end control module is also connected between the load and the receiving - end compensation network. The receiving - end control module includes a receiving - end voltage detection unit, a receiving - end current detection unit, a comparison unit, and a receiving - end DSP chip. The receiving - end voltage detection unit is connected in parallel between the output ports of the high - frequency rectifier filter. The receiving - end current detection unit is connected in series between the output port of the high - frequency rectifier filter and the load. The receiving - end voltage detection unit and the receiving - end current detection unit are also connected to the comparison unit at the same time. The comparison unit is connected to the receiving - end DSP chip. The receiving - end DSP chip is connected to the control port of the receiving - end compensation network. The receiving - end voltage detection unit is used to detect the charging voltage value provided to the load. The receiving - end current detection unit is used to detect the charging current value provided to the load. The comparison unit is used to compare the detected charging current value and charging voltage value with the corresponding current value and voltage value of the load charging requirement respectively. The receiving - end DSP chip is used to control and adjust the equivalent capacitance values of the bidirectional switch S and the capacitor C in the receiving - end compensation network according to the comparison result of the comparison unit, so as to maintain the charging current and voltage of the load to meet the charging requirement. s2 to maintain the charging current and voltage of the load to meet the charging requirement.

[0010] Further, a receiving - end driving circuit is also connected between the receiving - end DSP chip and the receiving - end compensation network. The receiving - end DSP chip controls and adjusts the receiving - end compensation network through the receiving - end driving circuit.

[0011] Further, the transmitting - end compensation network includes a capacitor C p .

[0012] Further, the capacitor C p , the capacitor C s1 and the capacitor C s2 The determination formula for the capacitance values is as follows:

[0013]

[0014] Where: C p is the capacitance value of the capacitor in the transmitting - end compensation network, C s1 , C s2 are the capacitance values of the capacitors in the receiving - end compensation network, ω is the angular frequency of the high - frequency AC power supply, f is the switching frequency of the high - frequency AC power supply, L p is the self - inductance of the transmitting coil, L s is the self - inductance of the receiving coil.

[0015] Further, the bidirectional switch S includes two power switch tubes, and the two power switch tubes are connected in reverse series.

[0016] The beneficial effects of the present invention are:

[0017] It can control the receiving - end compensation network according to the charging current and voltage requirements of the load, thus ensuring the charging safety of the load. And it can feedback the charging requirements of the load to the transmitting - end through the adjustment of the receiving - end compensation network, so as to adjust the output of the high - frequency AC power supply, enabling the high - frequency AC power supply to adjust its output according to the load requirements, achieving segmented constant - current and constant - voltage output, as well as fast and stable switching between the constant - current mode and the constant - voltage mode. It is not necessary to estimate the mutual inductance between the transmitting coil and the receiving coil. Compared with the traditional closed - loop control method that realizes wireless communication between the transmitting end and the receiving end, the demand feedback can be directly achieved through the system characteristics, which can reduce the limitation of wireless communication on the application scenario and greatly improve the feasibility of the wireless charging system in different scenarios. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 is a schematic block diagram of the circuit structure of a wireless charging system of the present invention;

[0019] Figure 2 is an equivalent circuit diagram of a wireless charging system according to an embodiment of the present invention;

[0020] Figure 3 is a structure diagram of a receiving - end compensation network according to an embodiment of the present invention;

[0021] Figure 4 is a schematic diagram of the working principle of a receiving - end compensation network according to an embodiment of the present invention;

[0022] Wherein: 1. High - frequency AC power supply, 2. Transmitting - end compensation network, 3. Transmitting coil, 4. Receiving coil, 5. Receiving - end compensation network, 6. High - frequency rectifier filter, 7. Load, 8. Transmitting - end control module, 81. Transmitting - end voltage detection unit, 82. Transmitting - end current detection unit, 83. Input impedance calculation unit, 84. Transmitting - end DSP chip, 85. Transmitting - end drive circuit, 9. Receiving - end control module, 91. Receiving - end voltage detection unit, 92. Receiving - end current detection unit, 93. Comparison unit, 94. Receiving - end DSP chip, 95. Receiving - end drive circuit. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0023] The present invention will be further described below with reference to the drawings and embodiments.

[0024] Embodiment:

[0025] An anti - offset wireless charging system with segmented constant - current and constant - voltage output, as Figure 1As shown in the figure, it includes a transmitting end and a receiving end. The transmitting end includes a high-frequency AC power supply 1, a transmitting-end compensation network 2, and a transmitting coil 3. The output port of the high-frequency AC power supply 1 is connected to the input port of the transmitting-end compensation network 2, and the transmitting coil 3 is connected to the output port of the transmitting-end compensation network 2. The receiving end includes a receiving coil 4, a receiving-end compensation network 5, a high-frequency rectifier filter 6, and a load 7. The receiving coil 4 is connected to the input port of the receiving-end compensation network 5, the output port of the receiving-end compensation network 5 is connected to the input port of the high-frequency rectifier filter 6, and the output port of the high-frequency rectifier filter 6 is connected to the load 7. Both the transmitting-end compensation network 2 and the receiving-end compensation network 5 are series compensation.

[0026] A transmitting-end control module 8 is also connected between the high-frequency AC power supply 1 and the transmitting-end compensation network 2. The transmitting-end control module 8 includes a transmitting-end voltage detection unit 81, a transmitting-end current detection unit 82, an input impedance calculation unit 83, and a transmitting-end DSP chip 84. The transmitting-end current detection unit 82 is connected in series between the output port of the high-frequency AC power supply 1 and the input port of the transmitting-end compensation network 2. The transmitting-end voltage detection unit 81 is connected in parallel between the output ports of the high-frequency AC power supply 1. The transmitting-end voltage detection unit 81 and the transmitting-end current detection unit 82 are also connected to the input impedance calculation unit 83 at the same time. The input impedance calculation unit 83 is connected to the transmitting-end DSP chip 84, and the transmitting-end DSP chip 84 is connected to the control port of the high-frequency AC power supply 1. The transmitting-end voltage detection unit 81 is used to detect the voltage value output by the high-frequency AC power supply 1. The transmitting-end current detection unit 82 is used to detect the current value output by the high-frequency AC power supply 1. The input impedance calculation unit 83 is used to calculate the phase angle of the input impedance according to the detected voltage value and current value. The transmitting-end DSP chip 84 is used to control and adjust the output voltage value of the high-frequency AC power supply 1 according to the calculated phase angle of the input impedance.

[0027] A transmitting-end drive circuit 85 is also connected between the transmitting-end DSP chip 84 and the high-frequency AC power supply 1. The transmitting-end DSP chip 84 adjusts the output voltage of the high-frequency AC power supply 1 through the transmitting-end drive circuit 85.

[0028] The receiving-end compensation network 5 includes a capacitor C s1 、a capacitor C s2 and a bidirectional switch S. One end of the capacitor C s1 is connected to the receiving coil 4, and the other end is connected to one end of the capacitor C s2 . The other end of the capacitor C s2 is connected to the high-frequency rectifier filter 6. The bidirectional switch S is connected in parallel to the capacitor C s2 .

[0029] A receiving - end control module 9 is also connected between the load 7 and the receiving - end compensation network 5. The receiving - end control module 9 includes a receiving - end voltage detection unit 91, a receiving - end current detection unit 92, a comparison unit 93, a receiving - end DSP chip 94, and a receiving - end driving circuit 95. The receiving - end voltage detection unit 91 is connected in parallel between the output ports of the high - frequency rectifier filter 6. The receiving - end current detection unit 92 is connected in series between the output port of the high - frequency rectifier filter 6 and the load 7. The receiving - end voltage detection unit 91 and the receiving - end current detection unit 92 are also simultaneously connected to the comparison unit 93. The comparison unit 93 is connected to the receiving - end DSP chip 94. The receiving - end DSP chip 94 is connected to the receiving - end driving circuit 95. The receiving - end driving circuit 95 is connected to the control port of the receiving - end compensation network 5. The receiving - end voltage detection unit 91 is used to detect the charging voltage value provided to the load 7. The receiving - end current detection unit 92 is used to detect the charging current value provided to the load 7. The comparison unit 93 is used to compare the detected charging current value and charging voltage value with the corresponding current value and voltage value of the load 7's charging requirement respectively. The receiving - end DSP chip 94 is used to control the receiving - end compensation network 5 to adjust the equivalent capacitance value of the bidirectional switch S and the capacitor C through the receiving - end driving circuit 95 according to the comparison result of the comparison unit 93, so as to maintain the charging current and voltage of the load 7 to meet the charging requirement. Here, the comparison unit 93 is also connected to the load 7 to obtain the charging requirement from the load 7 and obtain the current value and voltage value required for comparison from the charging requirement. s2 The comparison unit 93 is also connected to the load 7 to obtain the charging requirement from the load 7 and obtain the current value and voltage value required for comparison from the charging requirement, so as to maintain the charging current and voltage of the load 7 to meet the charging requirement.

[0030] The transmitting - end compensation network 2 includes a capacitor C p .

[0031] The capacitor C p , capacitor C s1 and capacitor C s2 The determination formula for the capacitance value is as follows:

[0032]

[0033] Where: C p is the capacitance value of the capacitor in the transmitting - end compensation network, C s1 , C s2 are the capacitance values of the capacitors in the receiving - end compensation network, ω is the angular frequency of the high - frequency AC power supply, f is the switching frequency of the high - frequency AC power supply, L p is the self - inductance of the transmitting coil, L s is the self - inductance of the receiving coil.

[0034] The bidirectional switch S includes two power switch tubes, and the two power switch tubes are connected in reverse series.

[0035] By controlling the on and off of the bidirectional switch S, the charging voltage and charging current applied to the load 7 can be adjusted.

[0036] At the beginning of wireless charging, first, the and output by the high-frequency AC power supply 1 are detected in real time. and Then, according to the detected in and in the phase angle θ of the input impedance of the wireless charging system is calculated. 0 Finally, when it is less than the preset threshold θ p the output voltage U in of the high-frequency AC power supply 1 is adjusted at the phase angle θ 0 When it is less than the preset threshold θ b the overall input impedance of the wireless charging system is in a pure impedance state. To ensure that the charging current I b and the charging voltage U p can meet the corresponding charging current I p and charging voltage U b in the charging requirements of the load 7, the receiving-end control module 9 detects I b and U b respectively, and then compares I r with the charging current demand value I b and adjusts the opening and closing of the bidirectional switch S in the receiving-end compensation network 5, that is, adjusts the equivalent capacitance value of SC in the receiving-end compensation network 5, to ensure that the charging current I b and the charging voltage U p can be consistent with the charging current I p and the charging voltage U b and at the same time ensure the safety of the load 7 during charging, preventing the charging current I b or the charging voltage U s from being too large and causing a failure of the load 7. And during the process of adjusting the receiving-end compensation network 5, the overall input impedance will change. The transmitting-end control module 8 can obtain the charging status of the receiving end through the change of the input impedance, and adjust the on and off of the power switch tube in the transmitting-end high-frequency AC power supply 1 according to the change of the input impedance, so as to adjust the output voltage of the high-frequency AC power supply 1, so that the charging of the load 7 can be maintained in a state that meets the charging requirements.

[0037] The equivalent circuit diagram of the anti-offset staged constant current and constant voltage output wireless charging system of this embodiment is as Figure 2 shown. In the analysis of the equivalent circuit diagram, the switching state of the power switch in the receiving-end compensation network is not considered. Let C s represent the equivalent capacitance parameter of the receiving-end compensation network, and let C pRepresents the equivalent capacitance parameter of the capacitor in the transmitter compensation network 2, and the high-frequency rectifier filter 6 and the load 7 are equivalent to a resistor R eq , the current flowing through the resistor R eq and the resistor R eq The voltages across both ends are respectively represented by and respectively. The output voltage of the high-frequency AC power supply 1 is represented as The output current of the high-frequency AC power supply 1 is represented as At the same time, the transmitter line impedance is equivalent to a resistor R p . From Figure 2 , it can be seen that when the output voltage of the high-frequency AC power supply 1 is constant, the receiver output is a constant current characteristic, and when the output current of the high-frequency AC power supply 1 is constant, the receiver output is a constant voltage characteristic. Thus, it can be known that the receiver control module 9 adjusts the receiver control network according to the charging demand, and can also feedback the charging demand to the transmitter during the adjustment process, thereby realizing the switching of the charging mode. The charging demand can be feedback only through the input impedance of the wireless charging system, without the need to additionally add communication equipment, enabling the wireless charging system to be applicable to more usage scenarios.

[0038] The structural diagram of the receiver compensation network 5 is as shown in Figure 3 . By changing the duty cycle of the power switch tube, the charging and discharging of the capacitor C s2 is controlled, thereby controlling the equivalent capacitance value of the receiver compensation network 5.

[0039] Based on Figure 3 the receiver network structure shown, the working principles of the power switch tube and the capacitor in the receiver compensation network 5 can be known. As shown in Figure 4 , by applying the PWM trigger pulses shown in Figure 4 to the two power switch tubes, the periodic charging and discharging balance of the capacitor C s2 can be ensured, and the middle position of the two pulses is the zero-crossing point of the current waveform. After performing Fourier decomposition on the capacitor and the corresponding voltage waveform, the fundamental waveform is obtained. According to the fundamental waveform, the relationship between the equivalent capacitance value C s2 ' and the capacitor C s2 is:

[0040]

[0041] where d is the duty cycle of the two power switch tubes.

[0042] The above-described embodiments are only a preferred solution of the present invention, and do not impose any form of limitation on the present invention. There are other variations and modifications without exceeding the technical solutions recorded in the claims.

Claims

1. A wireless charging system with anti-offset and phased constant current and constant voltage output, characterized in that, it includes a transmitting end and a receiving end. The transmitting end includes a high-frequency AC power supply, a transmitting-end compensation network, and a transmitting coil. The output port of the high-frequency AC power supply is connected to the input port of the transmitting-end compensation network. The transmitting coil is connected to the output port of the transmitting-end compensation network. The receiving end includes a receiving coil, a receiving-end compensation network, a high-frequency rectifier filter, and a load. The receiving coil is connected to the input port of the receiving-end compensation network. The output port of the receiving-end compensation network is connected to the input port of the high-frequency rectifier filter. The output port of the high-frequency rectifier filter is connected to the load. Both the transmitting-end compensation network and the receiving-end compensation network are series compensations; A transmitting-end control module is also connected between the high-frequency AC power supply and the transmitting-end compensation network. The transmitting-end control module includes a transmitting-end voltage detection unit, a transmitting-end current detection unit, an input impedance calculation unit, and a transmitting-end DSP chip. The transmitting-end current detection unit is connected in series between the output port of the high-frequency AC power supply and the input port of the transmitting-end compensation network. The transmitting-end voltage detection unit is connected in parallel between the output ports of the high-frequency AC power supply. The transmitting-end voltage detection unit and the transmitting-end current detection unit are also connected to the input impedance calculation unit at the same time. The input impedance calculation unit is connected to the transmitting-end DSP chip. The transmitting-end DSP chip is connected to the control port of the high-frequency AC power supply. The transmitting-end voltage detection unit is used to detect the voltage value output by the high-frequency AC power supply. The transmitting-end current detection unit is used to detect the current value output by the high-frequency AC power supply. The input impedance calculation unit is used to calculate the phase angle of the input impedance according to the detected voltage value and current value. The transmitting-end DSP chip is used to control and adjust the output voltage value of the high-frequency AC power supply according to the calculated phase angle of the input impedance; A receiving-end control module is also connected between the load and the receiving-end compensation network. The receiving-end control module includes a receiving-end voltage detection unit, a receiving-end current detection unit, a comparison unit, and a receiving-end DSP chip. The receiving-end voltage detection unit is connected in parallel between the output ports of the high-frequency rectifier filter. The receiving-end current detection unit is connected in series between the output port of the high-frequency rectifier filter and the load. The receiving-end voltage detection unit and the receiving-end current detection unit are also connected to the comparison unit at the same time. The comparison unit is connected to the receiving-end DSP chip. The receiving-end DSP chip is connected to the control port of the receiving-end compensation network. The receiving-end voltage detection unit is used to detect the charging voltage value provided to the load. The receiving-end current detection unit is used to detect the charging current value provided to the load. The comparison unit is used to compare the detected charging current value and charging voltage value with the corresponding current value and voltage value of the load charging demand respectively. The receiving-end DSP chip is used to control and adjust the equivalent capacitance value of the bidirectional switch S and the capacitor C in the receiving-end compensation network according to the comparison result of the comparison unit, so as to maintain the charging current and voltage of the load to meet the charging demand. s2 to maintain the charging current and voltage of the load to meet the charging demand.

2. The wireless charging system with anti-offset and phased constant current and constant voltage output according to claim 1, characterized in that, a transmitting-end drive circuit is also connected between the transmitting-end DSP chip and the high-frequency AC power supply. The transmitting-end DSP chip adjusts the output voltage of the high-frequency AC power supply through the transmitting-end drive circuit.

3. The wireless charging system with anti-offset and phased constant current and constant voltage output according to claim 1, characterized in that, The receiving end compensation network includes capacitor C s1 , capacitor C s2 and bidirectional switch S. One end of the capacitor C s1 is connected to the receiving coil, and the other end is connected to one end of the capacitor C s2 . The other end of the capacitor C s2 is connected to the high-frequency rectifier filter, and the bidirectional switch S is connected in parallel to the capacitor C s2 .

4. The wireless charging system with anti-offset and phased constant current and constant voltage output according to claim 1, characterized in that, a receiving-end drive circuit is also connected between the receiving-end DSP chip and the receiving-end compensation network. The receiving-end DSP chip controls and adjusts the receiving-end compensation network through the receiving-end drive circuit.

5. The wireless charging system with anti-offset and phased constant current and constant voltage output according to claim 3, characterized in that, The transmitting end compensation network includes capacitor C p .

6. The wireless charging system with anti-offset and phased constant current and constant voltage output according to claim 5, characterized in that, the capacitor C p and the capacitor C s1 and the capacitor C s2 The formula for determining the capacitance value is as follows: Among them: C p is the capacitance value of the capacitor in the transmitter compensation network, C s1 , C s2 is the capacitance value of the capacitor in the receiver compensation network, ω is the angular frequency of the high-frequency AC power supply, f is the switching frequency of the high-frequency AC power supply, L p is the self-inductance of the transmitting coil, L s is the self-inductance of the receiving coil.

7. The wireless charging system with anti-offset and phased constant current and constant voltage output according to claim 3, characterized in that, The bidirectional switch S includes two power switch tubes, which are connected in reverse series between the two power switch tubes.

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