A method for controlling the wireless charging power of a two-wheeled electric vehicle

Abstract

This invention discloses a method for controlling the wireless charging power of a two-wheeled electric vehicle, including a dual-ended LCC resonant topology circuit. Based on the equivalent voltage source model of the dual-ended LCC resonant topology circuit, the wireless charging power is controlled through maximum power point tracking (MPPT) and load power / voltage regulation (PR / VR) to provide a constant power at a constant voltage / current level to the load. In this invention, during the maximum power point tracking (MPPT) control, the resonant frequency f of the transmitting coil is adjusted by regulating the variable tuning capacitor. t The resonant frequency f of the receiving coil r Equal to the inverter switching frequency f s In load power / voltage regulation (PR / VR) control, the output load P is controlled by using an FLC to control the inverter's duty cycle D. L and output load voltage V L Even when there is misalignment between the inductively coupled coils, the present invention can provide a constant power to the load with the required voltage / current level.

Description

Technical Field

[0001] This invention relates to the field of wireless charging technology, and in particular to a method for controlling the wireless charging power of a two-wheeled electric vehicle. Background Technology

[0002] In 2021, China's electric two-wheeler industry market size reached the world's largest, with over 300 million electric two-wheelers currently in use and 130 million charging sessions per day. However, the rapidly developing electric two-wheeler market has encountered many difficulties and problems in promoting new energy applications, such as low efficiency, high fire hazards, and a lack of technological iteration. Frequent electric vehicle charging accidents have led to the rise of the wireless charging ecosystem.

[0003] In recent years, wireless charging technology has received increasing attention in many fields. In magnetically coupled resonant wireless power transmission, ensuring the maximum transmission efficiency and reducing power loss for two-wheeled electric vehicles is crucial.

[0004] In wireless charging systems for two-wheeled electric vehicles, parameters such as magnetic coupling coefficient (k), mutual inductance (M), transmitting coil (L1), and receiving coil (L2) affect the power transmission characteristics of the system. Incomplete coupling (or misalignment) between the coupling coils is a major problem in wireless charging, which can lead to a decrease and fluctuation in system efficiency and load power.

[0005] Therefore, this patent proposes a method for controlling the wireless charging power of a two-wheeled electric vehicle, based on maximum power point tracking (MPPT) and load power / voltage regulation (PR / VR), so that even when the coupling coil of the wireless charging system of the two-wheeled electric vehicle is misaligned, it can still provide a constant power with the required voltage / current level to the load. Summary of the Invention

[0006] In order to solve the technical problems mentioned in the background art, a method for controlling the wireless charging power of two-wheeled electric vehicles is proposed.

[0007] To achieve the above objectives, the present invention adopts the following technical solution:

[0008] A method for controlling the wireless charging power of a two-wheeled electric vehicle includes a dual-terminal LCC resonant topology circuit. Based on the equivalent voltage source model of the dual-terminal LCC resonant topology circuit, the wireless charging power is controlled by maximum power point tracking (MPPT) and load power / voltage regulation (PR / VR) to provide constant power at voltage / current levels to the load.

[0009] In maximum power point tracking (MPPT) control, based on impedance matching, the variable tuning capacitor is adjusted to make the resonant frequency f of the transmitting coil... tThe resonant frequency f of the receiving coil r Equal to the inverter switching frequency f s The specific control steps are as follows:

[0010] S1. Read the resonant frequency f of the transmitting coil. t The resonant frequency f of the receiving coil r and inverter switching frequency f s ;

[0011] S2, when f t or f r ≠f s When, calculate the result with f according to the following formula (1) t =f r =f s C corresponding to time f1 (i+1) and C f2 If the value of (i+1) is not found, return to step S1;

[0012]

[0013] In the formula, ω is the angular velocity, L1 is the transmitting coil, and C f1 C1 is an adjustable resonant capacitor connected in parallel on the primary side, and L is an adjustable resonant capacitor connected in series on the primary side. f2 For the secondary side series compensation inductor, C f2 C1 is a parallel adjustable resonant capacitor on the secondary side, and C2 is a series adjustable resonant capacitor on the secondary side.

[0014] S3, Set C f1 (i+1)=C f1 C f2 (i+1)=C f2 C f1 C f2 The value is based on f t and f r The monitoring settings are configured by C. f1 C f2 It will change accordingly to maintain f t =f r =f s f t and f r The measurement is performed by measuring the transmitting coil L1, the receiving coil L2, the primary side series adjustable resonant capacitor C1, and the secondary side series adjustable resonant capacitor C2.

[0015] In load power / voltage regulation (PR / VR) control, the duty cycle D of the inverter is controlled based on a fuzzy controller (FLC) to control the output load P. L and output load voltage V L The specific steps are as follows:

[0016] S4. Set the adjustable voltage V R Read the load voltage V L ;

[0017] S5. Calculate the input function error e = V R -V L ;

[0018] S6. When |e|≥5, the duty cycle D is adjusted by the fuzzy controller FLC according to the following formula (2);

[0019]

[0020] In the formula, P L i is the load power, i2 is the secondary inductor current, and R is the load current. eq Z is the equivalent load resistance, u2 is the equivalent load resistance voltage, and Z is the voltage across the load resistance. in Z is the input impedance. sec Where M is the secondary impedance, and U is the mutual inductance between the primary and secondary coils. in This is the rectified input voltage;

[0021] S7. The membership function output by the fuzzy controller FLC is D, which is D(k) at the k-th sampling time.

[0022] Adjust the voltage V within each sampling interval R and load voltage V L Used to calculate the changes in the error (e), error (ce), and previous error (pe) signals, which are inputs to the fuzzy controller FLC;

[0023] ce = e - pe;

[0024] The duty cycle D of the full-bridge inverter is determined by fuzzy reasoning.

[0025] As a further description of the above technical solution:

[0026] In a two-terminal LCC resonant topology circuit, the DC input power supply is connected to the full-bridge inverter after passing through the input filter capacitor. The resonant inductance L of the primary-side LCC resonant circuit is... f1 One end is connected to the bridge arm of the full-bridge inverter, and the other end is connected to the other side of the bridge arm of the full-bridge inverter via the transmitting coil L1. One end of the adjustable resonant capacitor C2 in the secondary LCC resonant circuit is connected to the rectifier bridge, and the other end is connected to the resonant inductor L. f2 Connected to the rectifier bridge, with the output terminal connected to the output capacitor C. O and load resistance R L .

[0027] As a further description of the above technical solution:

[0028] In equation (2), the secondary impedance Z sec The following formula (3) is used to calculate:

[0029]

[0030] In the formula, L2 is the receiving coil.

[0031] As a further description of the above technical solution:

[0032] In equation (2), the input impedance Z in The following formula (4) is used to calculate:

[0033]

[0034] In the formula, Z refl This is the reflection impedance.

[0035] As a further description of the above technical solution:

[0036] In equation (4), the reflection impedance Z refl The following formula (5) is used to calculate:

[0037]

[0038] In the formula, k is the magnetic coupling coefficient, i1 is the primary winding current, and i2 is the secondary winding current. As a further description of the above technical solution:

[0039] In equation (5), i1 and i2 are calculated using the following equation (6):

[0040]

[0041] As a further description of the above technical solution:

[0042] The system efficiency η of the wireless charging system is calculated using the following formula (8):

[0043]

[0044] In the formula, P in This refers to the input power.

[0045] In summary, due to the adoption of the above technical solutions, the beneficial effects of this invention are: By controlling the wireless charging power through maximum power point tracking (MPPT) and load power / voltage regulation (PR / VR), a constant power level of voltage / current is provided to the load. In the maximum power point tracking (MPPT) control, the resonant frequency f of the transmitting coil is adjusted by regulating the variable tuning capacitor. t The resonant frequency f of the receiving coil r Equal to the inverter switching frequency fs In load power / voltage regulation (PR / VR) control, the output load P is controlled by using an FLC to control the inverter's duty cycle D. L and output load voltage V L Even when there is misalignment between the inductively coupled coils, the present invention can provide a constant power to the load with the required voltage / current level. Attached Figure Description

[0046] Figure 1 A schematic diagram of a dual-terminal LCC resonant topology circuit structure is shown in the embodiment of the present invention for a method for controlling the wireless charging power of a two-wheeled electric vehicle.

[0047] Figure 2 A schematic diagram of an equivalent voltage source model is shown for a method for controlling the wireless charging power of a two-wheeled electric vehicle according to an embodiment of the present invention.

[0048] Figure 3 A flowchart illustrating the maximum power point tracking (MPPT) process of a wireless charging power control method for a two-wheeled electric vehicle according to an embodiment of the present invention is shown.

[0049] Figure 4 A schematic flowchart of the load power / voltage regulation (PR / VR) process of a wireless charging power control method for a two-wheeled electric vehicle provided according to an embodiment of the present invention is shown.

[0050] Figure 5 The load output power P of a wireless charging power control method for a two-wheeled electric vehicle according to an embodiment of the present invention is shown. L Relationship diagram with mutual inductance M. Detailed Implementation

[0051] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0052] Example 1

[0053] A two-wheeled electric vehicle wireless charging system consists of a transmitter and a receiver. The transmitter includes a primary-side rectifier fed from the grid, a full-bridge inverter connected to the DC output voltage of the primary-side rectifier, and a primary-side resonant cavity connected to the high-frequency AC excitation generated by the inverter output. The receiver includes a secondary-side resonant cavity that generates an induced voltage based on electromagnetic induction. The output of the secondary-side resonant cavity is supplied to a secondary-side rectifier, and the DC voltage output by the secondary-side rectifier is used to power the load battery. The system operates at the inverter switching frequency f. s Equal to the resonant frequency f of the receiving coil r At this time, maximum efficiency can be achieved.

[0054] Please see Figure 1-5 The present invention provides a technical solution: a method for controlling the wireless charging power of a two-wheeled electric vehicle, including a dual-terminal LCC resonant topology circuit, and based on the equivalent voltage source model of the dual-terminal LCC resonant topology circuit, controlling the wireless charging power through maximum power point tracking (MPPT) and load power / voltage regulation (PR / VR) to provide constant power at voltage / current levels to the load;

[0055] In a two-terminal LCC resonant topology circuit, the DC input power supply is connected to the full-bridge inverter after passing through the input filter capacitor. The resonant inductance L of the primary-side LCC resonant circuit is... f1 One end is connected to the bridge arm of the full-bridge inverter, and the other end is connected to the other side of the bridge arm of the full-bridge inverter via the transmitting coil L1. One end of the adjustable resonant capacitor C2 in the secondary LCC resonant circuit is connected to the rectifier bridge, and the other end is connected to the resonant inductor L. f2 Connected to the rectifier bridge, with the output terminal connected to the output capacitor C. O and load resistance R L ;

[0056] In maximum power point tracking (MPPT) control, based on impedance matching, the variable tuning capacitor is adjusted to make the resonant frequency f of the transmitting coil... t The resonant frequency f of the receiving coil r Equal to the inverter switching frequency f s The specific control steps are as follows:

[0057] S1. Read the resonant frequency f of the transmitting coil. t The resonant frequency f of the receiving coil r and inverter switching frequency f s ;

[0058] S2, when f t or f r ≠f s When, calculate the result with f according to the following formula (1) t =f r =f s C corresponding to timef1 (i+1) and C f2 If the value of (i+1) is not found, return to step S1;

[0059]

[0060] In the formula, ω is the angular velocity, L1 is the transmitting coil, and C f1 C1 is an adjustable resonant capacitor connected in parallel on the primary side, and L is an adjustable resonant capacitor connected in series on the primary side. f2 For the secondary side series compensation inductor, C f2 C1 is a parallel adjustable resonant capacitor on the secondary side, and C2 is a series adjustable resonant capacitor on the secondary side.

[0061] S3, Set C f1 (i+1)=C f1 C f2 (i+1)=C f2 C f1 C f2 The value is based on f t and f r The monitoring settings are configured by C. f1 C f2 It will change accordingly to maintain f t =f r =f s f t and f r The measurement is performed by measuring the transmitting coil L1, the receiving coil L2, the primary side series adjustable resonant capacitor C1, and the secondary side series adjustable resonant capacitor C2.

[0062] In load power / voltage regulation (PR / VR) control, the duty cycle D of the inverter is controlled based on a fuzzy controller (FLC) to control the output load P. L and output load voltage V L The specific steps are as follows:

[0063] S4. Set the adjustable voltage V R Read the load voltage V L ;

[0064] S5. Calculate the input function error e = V R -V L ;

[0065] S6. When |e|≥5, the duty cycle D is adjusted by the fuzzy controller FLC according to the following formula (2);

[0066]

[0067] In the formula, P L i is the load power, i2 is the secondary inductor current, and R is the load current. eqZ is the equivalent load resistance, u2 is the equivalent load resistance voltage, and Z is the voltage across the load resistance. in Z is the input impedance. sec Where M is the secondary impedance, and U is the mutual inductance between the primary and secondary coils. in This is the rectified input voltage;

[0068] Secondary impedance Z sec The following formula (3) is used to calculate:

[0069]

[0070] In the formula, L2 is the receiving coil;

[0071] Input impedance Z in The following formula (4) is used to calculate:

[0072]

[0073] In the formula, Z refl Reflection impedance;

[0074] Reflection impedance Z refl The following formula (5) is used to calculate:

[0075]

[0076] In the formula, k is the magnetic coupling coefficient, i1 is the primary winding current, and i2 is the secondary winding current.

[0077] i1 and i2 are calculated using the following formula (6):

[0078]

[0079] S7. The membership function output by the fuzzy controller FLC is D, which is D(k) at the k-th sampling time.

[0080] Adjust the voltage V within each sampling interval R and load voltage V L Used to calculate the changes in the error (e), error (ce), and previous error (pe) signals, which are inputs to the fuzzy controller FLC;

[0081] ce = e - pe;

[0082] The duty cycle D of the full-bridge inverter is determined by fuzzy reasoning. For example, if the output voltage continues to gradually increase when the current is low during charging, the fuzzy controller will maintain the voltage increase until the set point is reached. A drop in the output voltage level will trigger the fuzzy controller to increase the output voltage of the converter by modifying the modulation impedance matching of the converter.

[0083] Furthermore, the system efficiency η of the wireless charging system is calculated using the following equation (8):

[0084]

[0085] In the formula, P in This refers to the input power.

[0086] The value of M varies depending on the incomplete coupling between the inductively coupled coils. Figure 5 The load output power P is shown in three cases: no MPPT control, MPPT control alone, and the MPPT and PR / VR control proposed in this invention. L A comparison.

[0087] Figure 5 The results show that, without MPPT control, when M < 35 kW, P L It increases slightly with the increase of M, and under MPPT control, P L It decreases significantly as M increases;

[0088] At M > 35KW, the two curves with and without MPPT control are very similar, where P L Both decrease slightly as M increases;

[0089] However, using the MPPT and PR / VR control methods proposed in this invention, when M changes, the output load P... L Constant, output load voltage V L That is, even if the coupling coil of the wireless charging system for two-wheeled electric vehicles is misaligned, it can still provide a constant power with the required voltage / current level to the load.

[0090] Preferably, the prior art provides an adaptive frequency tracking method that continuously tracks the maximum η to the load at an ideal frequency. However, this method cannot perform power regulation, i.e., it cannot achieve voltage regulation. But since the required load voltage is adjusted according to the battery charging state and load changes, the voltage regulation function is particularly important. Therefore, the MPPT and PR / VR control method proposed in this invention can provide the load with constant power at the required voltage / current level even when there is misalignment between the inductively coupled coils.

[0091] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A method for controlling the wireless charging power of a two-wheeled electric vehicle, characterized in that, It includes a dual-terminal LCC resonant topology circuit, and based on the equivalent voltage source model of the dual-terminal LCC resonant topology circuit, it controls the wireless charging power through maximum power point tracking (MPPT) and load power / voltage regulation (PR / VR) to provide constant power at voltage / current levels to the load; In maximum power point tracking (MPPT) control, based on impedance matching, the variable tuning capacitor is adjusted to make the resonant frequency f of the transmitting coil... t The resonant frequency f of the receiving coil r Equal to the inverter switching frequency f s The specific control steps are as follows: S1. Read the resonant frequency f of the transmitting coil. t The resonant frequency f of the receiving coil r and inverter switching frequency f s ; S2, when f t or f r ≠f s When, calculate the relationship with f according to the following formula (1) t =f r =f s C corresponding to time f1 (i+1) and C f2 If the value of (i+1) is not found, return to step S1; ——（1） In the formula, ω is the angular velocity, L1 is the transmitting coil, and C is the angular velocity. f1 C1 is an adjustable resonant capacitor connected in parallel on the primary side, and L is an adjustable resonant capacitor connected in series on the primary side. f2 For the secondary side series compensation inductor, C f2 C1 is a parallel adjustable resonant capacitor on the secondary side, and C2 is a series adjustable resonant capacitor on the secondary side. S3, Set C f1 (i+1)=C f1 C f2 (i+1)=C f2 C f1 C f2 The value is based on f t and f r The monitoring settings are configured by C. f1 C f2 It will change accordingly to maintain f t =f r =f s f t and f r The measurement is performed by measuring the transmitting coil L1, the receiving coil L2, the primary side series adjustable resonant capacitor C1, and the secondary side series adjustable resonant capacitor C2. In load power / voltage regulation (PR / VR) control, the duty cycle D of the inverter is controlled based on a fuzzy controller (FLC) to control the output load P. L and output load voltage V L The specific steps are as follows: S4. Set the adjustable voltage V R Read the load voltage V L ; S5. Calculate the input function error e=V R -V L ; S6, when At that time, the duty cycle D is adjusted by the fuzzy controller FLC according to the following formula (2); ——（2） In the formula, P L i is the load power, i2 is the secondary inductor current, and R is the load current. eq Z is the equivalent load resistance, u2 is the equivalent load resistance voltage, and Z is the voltage across the load resistance. in Z is the input impedance. sec Where M is the secondary impedance, and U is the mutual inductance between the primary and secondary coils. in This is the rectified input voltage; S7. The membership function output by the fuzzy controller FLC is D, which is D(k) at the kth sampling time. Adjust the voltage V within each sampling interval R and load voltage V L Used to calculate the changes in the error (e), error (ce), and previous error (pe) signals, which are inputs to the fuzzy controller FLC; ce = e − pe; The duty cycle D of the full-bridge inverter is determined by fuzzy reasoning. In equation (2), the input impedance Z in The following formula (4) is used to calculate: ——（4） In the formula, Z refl Reflection impedance; In equation (4), the reflection impedance Z refl The following formula (5) is used to calculate: ——（5） In the formula, k is the magnetic coupling coefficient, i1 is the primary coil current, and i2 is the secondary coil current.

2. The method for controlling the wireless charging power of a two-wheeled electric vehicle according to claim 1, characterized in that, In a two-terminal LCC resonant topology circuit, the DC input power supply is connected to the full-bridge inverter after passing through the input filter capacitor. The resonant inductance L of the primary-side LCC resonant circuit is... f1 One end is connected to the bridge arm of the full-bridge inverter, and the other end is connected to the other side of the bridge arm of the full-bridge inverter via the transmitting coil L1. One end of the adjustable resonant capacitor C2 in the secondary LCC resonant circuit is connected to the rectifier bridge, and the other end is connected to the resonant inductor L. f2 Connected to the rectifier bridge, with the output terminal connected to the output capacitor C. O and load resistance R L .

3. The method for controlling the wireless charging power of a two-wheeled electric vehicle according to claim 1, characterized in that, In equation (2), the secondary impedance Z sec The following formula (3) is used to calculate: ——（3） In the formula, L2 is the receiving coil.

4. The method for controlling the wireless charging power of a two-wheeled electric vehicle according to claim 1, characterized in that, In equation (5), i1 and i2 are calculated using the following equation (6): ——（6）。 5. The method for controlling the wireless charging power of a two-wheeled electric vehicle according to claim 1, characterized in that, System efficiency of wireless charging system The following formula (8) is used to calculate: ——（8） In the formula, P in This refers to the input power.

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