Alternating current charging circuit, charging method of power battery and vehicle

Abstract

The invention relates to the technical field of charging, in particular to an alternating current charging circuit, a charging method of a power battery and a vehicle, and the alternating current charging circuit comprises a single-stage topology charger, the power battery, a three-phase inverter, a three-phase motor, a first switch module, a second switch module and a control module; the single-stage topology charger, the power battery and the first switch module are connected to form a first charging loop; the single-stage topology charger, the power battery, the three-phase inverter, the three-phase motor and the second switch module are connected to form a second charging loop; the control module is used for acquiring the output current of the single-stage topology charger and the maximum allowable charging current of the power battery, and controlling the first charging loop to be closed to charge the power battery when the output current of the single-stage topology charger is smaller than the maximum allowable charging current of the power battery; otherwise, controlling the second charging loop to be closed to charge the power battery. According to the invention, the adverse effect of large ripple current on a rear-end high-voltage electric appliance and a power battery is avoided.

Description

Technical Field

[0001] The present invention relates to the technical field of charging technology, and in particular to an AC charging circuit, a charging method for a power battery, and a vehicle. Background Art

[0002] With the global emphasis on environmental protection and sustainable energy development, the new energy vehicle industry has entered a golden period of rapid development. As a core component of new energy vehicles, the performance and technological upgrades of on-board chargers (OBCs) play a vital role in the promotion and application of new energy vehicles.

[0003] With the development of new energy vehicles, onboard chargers must not only meet basic AC / DC conversion and power the vehicle's low-voltage system, but also continuously optimize towards higher power density, lighter weight, and lower cost. Traditional onboard chargers often utilize a two-stage PFC (power factor correction) topology. While this structure achieves relatively stable power conversion and output, it has several significant drawbacks. The two-stage topology is relatively complex, involving two power conversion circuits. This not only leads to redundant circuitry but also utilizes a large number of components, resulting in a larger and heavier onboard charger. For electric vehicles with limited onboard space, this larger size and weight not only compromise the overall vehicle layout but also impact performance, such as increased energy consumption and reduced range. Furthermore, the large number of components and complex structure increase raw material costs, assembly costs, and labor hours during the manufacturing process, resulting in high overall product costs and weakening market competitiveness.

[0004] To overcome the shortcomings of the traditional two-stage topology, the industry is gradually shifting on-board chargers from a two-stage PFC topology to a single-stage PFC topology (referred to as a single-stage charger). Compared to the traditional two-stage topology, the single-stage topology eliminates one power conversion circuit stage, resulting in a simpler circuit structure and significantly fewer components. This structural optimization offers several significant advantages. First, in terms of size and weight, the reduced number of components and simplified structure reduce the size and weight of single-stage chargers. This is crucial for electric vehicles, where space is at a premium, facilitating a more rational vehicle layout and improving overall performance. Second, in terms of cost, single-stage chargers reduce raw material costs, assembly costs, and production hours during the manufacturing process, thereby reducing overall product costs, which is crucial for improving product competitiveness in the market.

[0005] However, while the single-stage topology offers many advantages, it also introduces some new problems. Among them, output ripple is particularly prominent. During operation, a single-stage charger generates ripple current from the 100Hz power frequency after passing through the single-stage PFC circuit, with the peak current reaching approximately twice that of the original two-stage totem-pole PFC. (The totem-pole PFC circuit is a highly efficient single-stage PFC topology. It uses a specific switch combination and control method to shape the input current waveform to make it close to a sine wave and in phase with the input voltage, thereby improving the power factor and reducing harmonic pollution. The totem-pole PFC circuit mainly consists of two high-arm switches (such as MOSFETs) and two low-arm switches, arranged in a totem pole shape. The input voltage is connected to the midpoint of the switch through an inductor, and the output is connected to the capacitor and load.) This large ripple current will have an adverse effect on the operation of high-voltage electrical appliances at the back end. For example, during the battery charging process, excessive ripple current may cause the back-end battery charging to malfunction, affecting the normal charging process, and even damage the battery service life, shortening the battery cycle life and increasing the vehicle's operating cost.

[0006] Therefore, it is necessary to develop a new AC charging circuit, a charging method for a power battery, and a vehicle. Summary of the Invention

[0007] The object of the present invention is to provide an AC charging circuit, a method for charging a power battery, and a vehicle, which can reduce costs and avoid the adverse effects of large ripple currents on rear-end high-voltage electrical appliances and power batteries.

[0008] In order to achieve the above object, the technical solution adopted by the present invention is as follows: In a first aspect, an AC charging circuit according to the present invention includes a single-stage topology charger, a power battery, a three-phase inverter, a three-phase motor, a first switch module, a second switch module, and a control module; The single-stage topology charger, the power battery and the first switch module are connected to form a first charging circuit; The single-stage topology charger, power battery, three-phase inverter, three-phase motor and second switch module are connected to form a second charging circuit; The control module is used to obtain the output current of the single-stage topology charger and the maximum allowable charging current of the power battery, and when the output current of the single-stage topology charger is less than the maximum allowable charging current of the power battery, control the first charging circuit to close to charge the power battery; otherwise, control the second charging circuit to close to charge the power battery; the control module is respectively connected to the first switch module, the second switch module and the three-phase inverter.

[0009] In one possible implementation, the second charging circuit shares a three-phase inverter and three-phase motor with the vehicle-side DC charging circuit. This AC charging circuit fully utilizes the vehicle's existing DC charging circuit, effectively handling ripple current without adding additional hardware. This highly integrated design not only reduces R&D and production costs but also greatly facilitates subsequent mass production and integration, offering significant market value.

[0010] In one possible implementation, the first switch module includes at least one switch for controlling the on / off state of the first charging circuit; the second switch module includes at least one switch for controlling the on / off state of the second charging circuit. The first and second switch modules respectively control the on / off state of the first and second charging circuits, enabling flexible switching between the first and second charging circuits and improving the flexibility and adaptability of the system.

[0011] In one possible implementation, when controlling the closing of the second charging loop to charge the power battery, the control module is further configured to control the switching of the three-phase inverter, causing at least one phase of the three-phase motor winding to function as an inductor. This ensures that the DC power output of the single-stage charger remains within the permitted current range of the power battery. When controlling the closing of the second charging loop to charge the power battery, the switching of the three-phase inverter is controlled to cause at least one phase of the three-phase motor winding to function as an inductor. Based on the fast-charging and slow-discharging characteristics of the inductor, the DC power output of the single-stage charger is controlled within the permitted current range of the power battery according to δI = δV / (L*f). δI represents the current ripple, indicating the fluctuation range of the charging current and must be controlled within the permitted range of the power battery to avoid overcharging or battery damage. δV represents the voltage ripple, indicating the fluctuation range of the charging voltage and is typically determined by the output characteristics of the single-stage charger or system design. L represents the inductance value, representing the equivalent inductance of the three-phase motor winding when used as an inductor, which influences the magnitude of the current ripple. f is the switching frequency, which indicates the switching frequency of the three-phase inverter. The higher the frequency, the smaller the current ripple.

[0012] In one possible implementation, when controlling the second charging circuit to close and charge the power battery, the control module controls the upper bridge arm of the three-phase inverter to conduct, so that the current output by the single-stage topology charger flows through the three-phase inverter and then flows into the three-phase motor. At least one phase winding of the three-phase motor is used to control the DC power output of the single-stage topology charger to be within the current range allowed by the power battery. The current output by the single-stage topology charger flows through the upper bridge arm of the three-phase inverter and then flows into the three-phase motor.

[0013] In one possible implementation, when controlling the second charging circuit to close and charge the power battery, the control module controls the lower bridge arm of the three-phase inverter to conduct, so that the current output by the single-stage topology charger flows through the three-phase inverter and then flows into the three-phase motor. At least one phase winding of the three-phase motor is used to control the DC power output of the single-stage topology charger to be within the current range allowed by the power battery. The current output by the single-stage topology charger flows through the lower bridge arm of the three-phase inverter and then flows into the three-phase motor.

[0014] In one possible implementation, the upper arm of the three-phase inverter includes three switching transistors. When controlling the second charging loop to close to charge the power battery, the control module turns on at least one switching transistor in the upper arm. This allows the current output by the single-stage topology charger to flow through the at least one switching transistor in the upper arm and then into the three-phase motor.

[0015] In one possible implementation, the upper arm of the three-phase inverter includes three switching transistors. When the second charging loop is closed to charge the power battery, at least one switching transistor in the lower arm, controlled by the control module, is turned on. This allows the current output by the single-stage topology charger to flow through the at least one switching transistor in the lower arm and then into the three-phase motor.

[0016] In one possible implementation, the stator windings of the three-phase motor are connected in a Y-type configuration. This Y-type connection connects the first ends of the three windings of the three-phase motor together to form a common point, which is then connected to the power battery via a second switch module. The second ends of the three-phase windings are connected to the midpoints of the three bridge arms of the three-phase inverter, one for each connection. This Y-type connection connects the neutral point of the three-phase motor to the power battery, providing an electrical connection foundation for charging the second charging circuit while simplifying the circuit structure.

[0017] In a second aspect, a method for charging a power battery according to the present invention employs the AC charging circuit according to the present invention, and the method comprises the following steps: During the charging process, the output current of the single-stage topology charger and the maximum allowable charging current of the power battery are obtained in real time; When the output current of the single-stage topology charger is less than the maximum allowable charging current of the power battery, the first charging circuit is closed, the second charging circuit is disconnected, and the power battery is charged through the first charging circuit; When the output current of the single-stage topology charger is greater than or equal to the maximum allowable charging current of the power battery, the second charging circuit is closed, the first charging circuit is disconnected, and the power battery is charged through the second charging circuit.

[0018] A possible implementation also includes: By acquiring the power battery voltage and the power of the single-stage topology charger in real time, determining the power battery's requested charging current based on the voltage and power, and controlling the output current of the single-stage topology charger based on the requested charging current, the system achieves precise control of the charging process, improving charging stability and safety.

[0019] In a third aspect, a vehicle according to the present invention adopts the AC charging circuit according to the present invention.

[0020] It should be noted that various possible implementations of any of the above aspects can be combined under the premise that the solutions are not contradictory.

[0021] The present invention has the following beneficial effects: (1) Efficient charging control: When the output current of the single-stage topology charger is less than the maximum allowable charging current of the power battery, the present invention directly charges the power battery through the first charging circuit, avoiding unnecessary energy conversion and loss, thereby significantly improving charging efficiency. This direct charging method not only simplifies the charging process but also reduces energy loss during the conversion process, providing a more efficient and fast charging solution for the power battery.

[0022] (2) Ripple current suppression: The AC charging circuit of the present invention has an innovative design to address this issue. When the output current of the single-stage topology charger exceeds the maximum allowable charging current of the power battery, ripple current suppression is achieved through the windings of the three-phase motor. This design effectively reduces current fluctuations during the charging process, avoiding damage to the back-end high-voltage electrical equipment and power battery caused by excessive ripple current. At the same time, it ensures the stability and safety of battery charging, extends the battery life, reduces the cost of vehicle use, and perfectly solves the problem of output ripple caused by the single-stage topology structure.

[0023] (3) Significant cost-effectiveness: The single-stage PFC topology power supply adopted by this invention significantly simplifies the circuit design and reduces the number of key components such as inductors and capacitors compared to the traditional two-stage totem pole PFC solution. This design reduces the overall cost of this AC charging circuit by approximately RMB 100 compared to the traditional solution. The cost optimization is mainly due to the simplification of the circuit design and the reduction in the number of components used, which significantly improves the economic efficiency and market competitiveness of the product and effectively solves the problem of excessive cost of the traditional two-stage topology.

[0024] In summary, the AC charging circuit and power battery charging method proposed in the present invention show significant advantages in terms of efficient charging control, ripple current suppression, and cost-effectiveness, providing new solutions and development directions for electric vehicle charging technology. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 is a circuit diagram of the DC charging circuit in an embodiment of the present application; Figure 2 This is one of the flow charts of the method for charging the power battery described in the embodiment of the present application; Figure 3 This is the second flow chart of the method for charging the power battery described in the embodiment of the present application; In the figure: 1. Single-stage topology charger, 2. Power battery, 3. First switch module, 4. Second switch module, 5. Three-phase inverter, 6. Three-phase motor. DETAILED DESCRIPTION

[0026] The following will describe the embodiments of the present invention with reference to the accompanying drawings and preferred embodiments. Those skilled in the art will be able to understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention. It should be understood that the preferred embodiments are only for the purpose of illustrating the present invention and are not intended to limit the scope of protection of the present invention.

[0027] In the embodiments of the present application, in order to clearly describe the technical solutions of the embodiments of the present application, words such as "first" and "second" are used to distinguish between identical or similar items with substantially the same functions and effects. Those skilled in the art will understand that words such as "first" and "second" do not limit the quantity or execution order, and words such as "first" and "second" do not necessarily mean different. There is no order of precedence or priority between the technical features described by "first" and "second".

[0028] In the embodiments of this application, words such as "exemplary" or "for example" are used to indicate examples, illustrations, or descriptions. Any embodiment or design described as "exemplary" or "for example" in the embodiments of this application should not be construed as being preferred or advantageous over other embodiments or designs. Rather, the use of words such as "exemplary" or "for example" is intended to present the relevant concepts in a concrete manner to facilitate understanding.

[0029] In the embodiments of the present application, at least one can also be described as one or more, and multiple can be two, three, four or more, which is not limited in this application.

[0030] like Figure 1 As shown, in an embodiment of the present application, an AC charging circuit includes a single-stage charger 1, a power battery 2, a three-phase inverter 5, a three-phase motor 6, a first switch module 3, a second switch module 4, and a control module (not shown). The single-stage charger 1, the power battery 2, and the first switch module 3 are connected to form a first charging circuit. The single-stage charger 1, the power battery 2, the three-phase inverter 5, the three-phase motor 6, and the second switch module 4 are connected to form a second charging circuit. The control module is configured to obtain the output current of the single-stage charger 1 and the maximum allowable charging current of the power battery 2. When the output current of the single-stage charger 1 is less than the maximum allowable charging current of the power battery 2, the control module controls the first charging circuit to close and charge the power battery 2. Otherwise, the control module controls the second charging circuit to close and charge the power battery 2. The control module is connected to the first switch module 3, the second switch module 4, and the three-phase inverter 5, respectively.

[0031] like Figure 1 As shown, illustratively, the positive output terminal of the single-stage topology charger 1 is connected to the positive electrode of the power battery 2, and the negative output terminal of the single-stage topology charger 1 is connected to the negative electrode of the power battery 2 via the first switch module 3. The positive output terminal of the single-stage topology charger 1 is also connected to the first terminal of the three-phase inverter 5, and the second terminal of the three-phase inverter 5 is connected to the connection point between the negative output terminal of the single-stage topology charger 1 and the first switch module 3. The control terminal of the three-phase inverter 5 is connected to the control module, and the output terminal of the three-phase inverter 5 is connected to the three-phase motor 6. The output terminal of the three-phase motor 6 is also connected to the negative electrode of the power battery 2 via the second switch module 4.

[0032] In this embodiment of the present application, the AC charging circuit utilizes a single-stage topology charger 1 (i.e., the charger only has a single-stage PFC circuit), the core of which is a single-stage PFC topology power supply. In practical applications, the single-stage topology charger 1 generates ripple current during operation. To effectively address this issue, this AC charging circuit cleverly utilizes the windings of the three-phase motor 6 to suppress ripple current. From a cost-effectiveness perspective, compared to traditional two-stage totem-pole PFC solutions, the single-stage PFC topology power supply employed in this AC charging circuit significantly simplifies the circuit design and reduces the number of key components such as inductors and capacitors. Preliminary estimates suggest that this optimization can reduce overall costs by approximately 100 yuan, significantly improving the product's economic efficiency.

[0033] In one possible embodiment, the second charging circuit shares a three-phase inverter 5 and a three-phase motor 6 with the vehicle-side DC charging circuit. This AC charging circuit fully utilizes the vehicle's existing DC charging circuit, effectively handling ripple current without adding additional hardware. This highly integrated design not only reduces R&D and production costs but also greatly facilitates subsequent mass production and integration, resulting in extremely high market value.

[0034] like Figure 1 As shown, in a possible embodiment, the first switch module 3 includes at least one switch for controlling the on / off of the first charging circuit; the second switch module 4 includes at least one switch for controlling the on / off of the second charging circuit. Specifically: When the control module determines that the output current of the single-stage topology charger 1 is less than the maximum allowable charging current of the power battery 2, it controls the first switch module 3 to close and the second switch module 4 to open, thereby charging the power battery 2. When the control module determines that the output current of the single-stage topology charger 1 is greater than or equal to the maximum allowable charging current of the power battery 2, it controls the first switch module 3 to open and the second switch module 4 to close, thereby charging the power battery 2. The first switch module 3 and the second switch module 4 respectively control the on-off of the first and second charging circuits, enabling flexible switching between the first and second charging circuits and improving the flexibility and adaptability of the system.

[0035] like Figure 1 As shown, in a possible embodiment, the first switch module 3 adopts a main-slave relay, and the second switch module 4 adopts a DC negative relay.

[0036] like Figure 1 As shown, in a possible embodiment, when controlling the closing of the second charging circuit to charge the power battery 2, the control module is also used to control the switching action of the three-phase inverter 5, so that at least one phase winding of the three-phase motor 6 is used as an inductor, so as to control the DC power output by the single-stage topology charger 1 to be within the current range allowed by the power battery 2.

[0037] like Figure 1As shown, the three-phase inverter 5 exemplarily includes a first power switch unit, a second power switch unit, a third power switch unit, a fourth power switch unit, a fifth power switch, and a sixth power switch. The first power switch unit comprises a first switch tube S1 and a first diode VD1 in parallel; the second power switch unit comprises a second switch tube S2 and a second diode VD2 in parallel; the third power switch unit comprises a third switch tube S3 and a third diode VD3 in parallel; the fourth power switch unit comprises a fourth switch tube S4 and a fourth diode VD4 in parallel; the fifth power switch comprises a fifth switch tube S5 and a fifth diode VD5 in parallel; and the sixth power switch comprises a sixth switch tube S6 and a sixth diode VD6 in parallel. The control terminal of each power switch unit is connected to the control module. The first and fourth power switch units form the A-phase bridge leg; the fifth and second power switch units form the B-phase bridge leg; and the third and sixth power switch units form the C-phase bridge leg. The first switch S1 , the second switch S2 and the third switch S3 are upper arms of the three-phase inverter 5 , and the fourth switch S4 , the fifth switch S5 and the sixth switch S6 are lower arms of the three-phase inverter 5 .

[0038] like Figure 1 As shown, in one possible embodiment, when controlling the second charging circuit to close to charge the power battery 2, the control module controls at least one switch in the upper bridge arm to turn on. This allows the current output by the single-stage topology charger to flow through the at least one switch in the upper bridge arm and then into the three-phase motor.

[0039] In Example 1, when the control module determines that the output current of the single-stage charger 1 is greater than or equal to the maximum allowable charging current of the power battery 2, the control module controls the first, second, and third switches S1, S2, and S3 to all be turned on (serving only as a conduction loop). The DC power output by the single-stage charger 1 flows through the first, second, and third switches S1, S2, and S3 before flowing into the three-phase windings of the three-phase motor 6. The three-phase windings of the three-phase motor 6 control the DC power output of the single-stage charger 1 to within the allowable current range of the power battery 2.

[0040] Example 2: When the power battery 2 needs to be charged through the second charging circuit, the control module controls two of the switch tubes in the upper bridge arm to be turned on. For example, the first switch tube S1 and the second switch tube S2 are both turned on. At this time, the current output by the single-stage topology charger 1 passes through the first switch tube S1 and the second switch tube S2 of the three-phase inverter 5 and then flows into the three-phase motor 6. The DC power output by the single-stage topology charger 1 is controlled within the current range allowed by the power battery 2 through the two-phase windings of the three-phase motor 6.

[0041] Example 3: When the power battery 2 needs to be charged through the second charging circuit, the control module controls one of the switch tubes in the upper bridge arm to be turned on. Taking the control of the first switch tube S1 as an example, the current output by the single-stage topology charger 1 flows into the three-phase motor 6 after passing through the first switch tube S1 of the three-phase inverter 5. The DC power output by the single-stage topology charger 1 is controlled within the current range allowed by the power battery 2 through one-phase winding of the three-phase motor 6.

[0042] like Figure 1 As shown, in one possible embodiment, the control module is connected to the control terminals of the fourth switch S4, the fifth switch S5, and the sixth switch S6, respectively. When the control module determines that the output current of the single-stage topology charger 1 is greater than or equal to the maximum allowable charging current of the power battery 2, the control module controls the fourth switch S4, the fifth switch S5, and the sixth switch S6 to all be turned on. The DC power output by the single-stage topology charger 1 passes through the fourth switch S4, the fifth switch S5, and the sixth switch S6 and then flows into the three-phase windings of the three-phase motor 6.

[0043] Example 1: When the power battery 2 needs to be charged through the second charging circuit, the control module controls the fourth switch S4, the fifth switch S5, and the sixth switch S6 of the three-phase inverter 5 to be turned on (serving only as a conduction circuit). At this time, the current output by the single-stage topology charger 1 flows through the lower bridge arm of the three-phase inverter 5 and then into the three-phase motor 6. The three-phase windings of the three-phase motor 6 control the DC power output of the single-stage topology charger 1 to be within the current range allowed by the power battery 2.

[0044] Example 2: When the power battery 2 needs to be charged through the second charging circuit, the control module controls two of the switch tubes in the lower bridge arm to be turned on. For example, the fourth switch tube S4 and the fifth switch tube S5 are both turned on. At this time, the current output by the single-stage topology charger 1 passes through the fourth switch tube S4 and the fifth switch tube S5 of the three-phase inverter 5 and then flows into the three-phase motor 6. The DC power output by the single-stage topology charger 1 is controlled within the current range allowed by the power battery 2 through the two-phase windings of the three-phase motor 6.

[0045] Example 6: When the power battery 2 needs to be charged through the second charging circuit, the control module controls one of the switches in the lower bridge arm to be turned on. For example, the fourth switch S4 is controlled to be turned on. At this time, the current output by the single-stage topology charger 1 flows through the fourth switch S4 of the three-phase inverter 5 and then flows into the three-phase motor 6. The DC power output by the single-stage topology charger 1 is controlled within the current range allowed by the power battery 2 through one-phase winding of the three-phase motor 6.

[0046] like Figure 1As shown, the stator windings of the three-phase motor 6 are exemplarily connected in a Y-type configuration. This Y-type connection connects the first ends of the three windings (i.e., coils) of the three-phase motor 6 together to form a common point (commonly referred to as the neutral point or point N). The neutral point of the three-phase motor 6 is connected to the power battery 2 via a DC negative relay. The second ends of the three-phase windings are connected to the midpoints of the A-phase, B-phase, and C-phase bridge arms of the three-phase inverter 5, respectively. This Y-type connection connects the neutral point of the three-phase motor 6 to the power battery 2, providing an electrical connection foundation for charging the second charging circuit while simplifying the circuit structure.

[0047] like Figure 1 As shown, in a possible embodiment, an AC charging circuit further includes a capacitor C, the capacitor C is used to store energy, and the capacitor C is connected in parallel with the three-phase inverter 5.

[0048] In the embodiment of the present application, the charging path selection and control: Case 1: The output current of the single-stage topology charger 1 is less than the maximum allowable charging current of the power battery 2 Relay action: The control module closes the main negative relay and opens the DC negative relay. At this point, the single-stage topology charger 1, power battery 2, and main negative relay form a closed circuit (i.e., the first charging circuit is closed), and power battery 2 is directly charged through the single-stage topology charger 1.

[0049] Charging process: The single-stage topology charger 1 converts AC power into DC power, providing a stable charging current for the power battery 2.

[0050] Case 2: The output current of the single-stage topology charger 1 is greater than or equal to the maximum allowable charging current of the power battery 2 Relay action: The control module closes the DC negative relay, opens the main negative relay, and switches on either the upper or lower arm of the three-phase inverter 5. At this point, the single-stage charger 1, power battery 2, DC negative relay, three-phase motor 6, and three-phase inverter 5 form a closed circuit (i.e., the second charging circuit is closed). The high-voltage power output by the single-stage charger 1 is sequentially transmitted to the neutral line of the three-phase inverter 5 and the three-phase motor 6 before being output to charge the power battery 2.

[0051] Charging process: The single-stage topology charger 1 converts AC power into DC power. Since the upper bridge arm or the lower bridge arm of the three-phase inverter 5 is in the on state, the DC power output by the single-stage topology charger 1 flows through the three-phase inverter 5 and then flows into at least one winding of the three-phase motor 6. At this time, the winding of the three-phase motor 6 is equivalent to an inductor, and the DC power output by the single-stage topology charger 1 is controlled within the current range allowed by the power battery 2 through the inductor.

[0052] like Figure 2As shown, in an embodiment of the present application, a method for charging a power battery, using an AC charging circuit as in an embodiment of the present application, includes the following steps: During the charging process, the output current of the single-stage topology charger 1 and the maximum allowable charging current of the power battery 2 are obtained in real time.

[0053] When the output current of the single-stage topology charger 1 is less than the maximum allowable charging current of the power battery 2, the first charging circuit is closed, the second charging circuit is disconnected, and the power battery 2 is charged through the first charging circuit.

[0054] When the output current of the single-stage topology charger 1 is greater than or equal to the maximum allowable charging current of the power battery 2, the second charging circuit is closed, the first charging circuit is disconnected, and the power battery 2 is charged through the second charging circuit.

[0055] In one possible embodiment, the control module also obtains the voltage U of the power battery 2 and the power P of the single-stage topology charger 1 in real time, and obtains the requested charging current I of the power battery 2 by dividing the power P by the voltage U. The control module controls the output current of the single-stage topology charger 1 based on the requested charging current I. However, since the charger adopts a single-stage topology charger 1, during the operation of the single-stage topology charger 1, ripple current from the power frequency of 100 Hz is generated after passing through the single-stage PFC circuit, and the current peak value can reach about twice that of the original two-stage totem pole PFC.

[0056] For ease of understanding, let's take an example and assume that the requested charging current I of the power battery 2 is 6A. Due to the single-stage PFC of the single-stage topology charger 1, ripple current will be generated. At this time, the output current of the single-stage topology charger 1 is between 0A and 12A, and the maximum allowable charging current of the power battery 2 is 8A. To ensure the safety and service life of the power battery 2, currents greater than 8A need to be filtered out.

[0057] In the prior art, the AC charging circuit and the DC charging circuit are two independent charging systems. When the power battery 2 is charged through the AC charging circuit, the DC charging circuit is in an inoperative state. In the embodiment of the present application, in order to eliminate the adverse effects of ripple current on the power battery 2, the three-phase inverter 5 and the three-phase motor 6 in the DC charging circuit are used. That is, when the output current of the single-stage topology charger 1 is greater than or equal to the maximum allowable charging current of the power battery 2, the second charging circuit is entered. By turning on at least one switch tube in the upper bridge arm or at least one switch tube in the lower bridge arm of the three-phase inverter 5 in the DC charging circuit, when at least one switch tube in the upper bridge arm or at least one switch tube in the lower bridge arm is turned on, the windings in the three-phase motor 6 become inductors. This is equivalent to adding inductance to the charging circuit, and its inductive reactance will hinder current changes. According to different inductance requirements, different windings are connected, and the 8A-12A current is eliminated through the action of the inductor.

[0058] like Figure 3 As shown, in a possible embodiment, a method for charging a power battery includes the following specific steps: Step 1: Obtain the voltage and maximum allowable charging current of the power battery 2 , wherein the requested charging current of the power battery 2 is calculated according to the voltage of the power battery 2 .

[0059] Step 2: Obtain the output current of the single-stage topology charger 1.

[0060] Step 3: Determine whether the output current of the single-stage topology charger 1 is greater than or equal to the maximum allowable charging current of the power battery 2. If not, jump to step 4; if so, jump to step 5.

[0061] Step 4: Close the main and auxiliary relays, disconnect the DC negative relay, charge the power battery 2, and proceed to step 6.

[0062] Step 5: Close the DC negative relay, disconnect the main and auxiliary relays, and the control module controls one of the switch tubes of the upper bridge arm (or lower bridge arm) of the three-phase inverter 5 to turn on. The current passes through the winding of the three-phase motor 6 and flows through the neutral line to charge the power battery 2, and then enters step 6.

[0063] Step 6: Determine whether the power battery 2 is fully charged. If it is fully charged, jump to step 7; if not, jump to step 1.

[0064] Step 7: After the power battery 2 is fully charged, charging is completed.

[0065] In an embodiment of the present application, a vehicle adopts the AC charging circuit as in the embodiment of the present application.

[0066] The vehicle may be, but is not limited to, a pure electric vehicle (Pure Electric Vehicle / Battery Electric Vehicle, PEV / BEV), a hybrid electric vehicle (Hybrid Electric Vehicle, HEV), a range extended electric vehicle (Range Extended Electric Vehicle, REEV), a plug-in hybrid electric vehicle (Plug-in Hybrid Electric Vehicle, PHEV), a new energy vehicle (New Energy Vehicle), etc.

[0067] On the other hand, an electronic device is provided, which includes a processor and a memory, wherein at least one computer program is stored in the memory. When the at least one computer program is loaded and executed by the processor, the power battery charging method provided in the above-mentioned method embodiments can be implemented.

[0068] On the other hand, a computer-readable storage medium is provided, in which at least one computer program is stored. When the at least one computer program is loaded and executed by a processor, the power battery charging method provided in the above-mentioned method embodiments can be implemented.

[0069] On the other hand, a computer program product is provided. The computer program product includes a computer program or instructions. When the computer program or instructions are executed by a processor, the power battery charging method provided in the above method embodiments can be implemented.

[0070] It should be noted that when the instructions in the above-mentioned computer-readable storage medium or one or more instructions in the computer program product are executed by the processor of the electronic device, the various processes of the above-mentioned method embodiment are implemented and the same technical effect as the above-mentioned method can be achieved. To avoid repetition, they will not be repeated here.

[0071] Through the description of the above implementation methods, technical personnel in the relevant field can clearly understand that for the convenience and simplicity of description, only the division of the above-mentioned functional modules is used as an example. In actual applications, the above-mentioned functions can be distributed and completed by different functional modules as needed, that is, the internal structure of the device can be divided into different functional modules to complete the full classification or partial functions described above.

[0072] The above embodiments are preferred implementation modes of the present invention, but the implementation modes of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be considered as equivalent replacement methods and are included in the scope of protection of the present invention.

Claims

1. An AC charging circuit, characterized in that: It comprises a single-stage topology charger (1), a power battery (2), a three-phase inverter (5), a three-phase motor (6), a first switch module (3), a second switch module (4) and a control module; The single-stage topology charger (1), the power battery (2) and the first switch module (3) are connected to form a first charging circuit; The single-stage topology charger (1), the power battery (2), the three-phase inverter (5), the three-phase motor (6), and the second switch module (4) are connected to form a second charging circuit; The control module is used to obtain the output current of the single-stage topology charger (1) and the maximum allowable charging current of the power battery (2), and when the output current of the single-stage topology charger (1) is less than the maximum allowable charging current of the power battery (2), controls the first charging circuit to be closed to charge the power battery (2), otherwise controls the second charging circuit to be closed to charge the power battery (2); the control module is respectively connected to the first switch module (3), the second switch module (4) and the three-phase inverter (5).

2. The AC charging circuit according to claim 1, characterized in that: The second charging circuit and the vehicle-end DC charging circuit share a three-phase inverter (5) and a three-phase motor (6).

3. The AC charging circuit according to claim 1, characterized in that: The first switch module (3) includes at least one switch for controlling the on / off of the first charging circuit; the second switch module (4) includes at least one switch for controlling the on / off of the second charging circuit.

4. The AC charging circuit according to claim 3, characterized in that: When controlling the second charging circuit to close to charge the power battery (2), the control module is further used to control the switching action of the three-phase inverter (5), so that at least one phase winding of the three-phase motor (6) is used as an inductor, thereby controlling the direct current output by the single-stage topology charger (1) to be within the current range allowed by the power battery (2).

5. The AC charging circuit according to claim 4, characterized in that: When controlling the second charging circuit to be closed to charge the power battery (2), the upper bridge arm of the three-phase inverter (5) is controlled to be turned on through the control module, so that the current output by the single-stage topology charger (1) flows into the three-phase motor (6) after passing through the three-phase inverter (5), and the direct current output by the single-stage topology charger (1) is controlled to be within the current range allowed by the power battery (2) through at least one phase winding of the three-phase motor (6).

6. The AC charging circuit according to claim 4, characterized in that: When controlling the second charging circuit to be closed to charge the power battery (2), the control module controls the lower bridge arm of the three-phase inverter (5) to be turned on, so that the current output by the single-stage topology charger (1) flows into the three-phase motor (6) after passing through the three-phase inverter (5), and the direct current output by the single-stage topology charger (1) is controlled to be within the current range allowed by the power battery (2) through at least one phase winding of the three-phase motor (6).

7. The AC charging circuit according to claim 5, characterized in that: The upper bridge arm of the three-phase inverter (5) comprises three switch tubes, and when the second charging circuit is controlled to be closed to charge the power battery (2), at least one switch tube in the upper bridge arm is controlled to be turned on through the control module.

8. The AC charging circuit according to claim 6, characterized in that: The upper bridge arm of the three-phase inverter (5) comprises three switch tubes, and when the second charging loop is controlled to be closed to charge the power battery (2), at least one switch tube in the lower bridge arm controlled by the control module is turned on.

9. The AC charging circuit according to claim 1, characterized in that: The stator windings of the three-phase motor (6) are Y-connected. The Y-connection means that the first ends of the three windings of the three-phase motor (6) are connected together to form a common point, and the common point of the three-phase motor (6) is connected to the power battery (2) via the second switch module (4); the second ends of the three-phase windings are respectively connected to the midpoints of the three bridge arms of the three-phase inverter (5) in a one-to-one correspondence.

10. A method for charging a power battery, characterized in that: Using the AC charging circuit according to any one of claims 1 to 9, the method comprises the following steps: During the charging process, the output current of the single-stage topology charger (1) and the maximum allowable charging current of the power battery (2) are obtained in real time; When the output current of the single-stage topology charger (1) is less than the maximum allowable charging current of the power battery (2), the first charging circuit is closed, the second charging circuit is disconnected, and the power battery (2) is charged through the first charging circuit; When the output current of the single-stage topology charger (1) is greater than or equal to the maximum allowable charging current of the power battery (2), the second charging circuit is closed, the first charging circuit is disconnected, and the power battery (2) is charged through the second charging circuit.

11. The method for charging a power battery according to claim 10, characterized in that: Also includes: The voltage of the power battery (2) and the power of the single-stage topology charger (1) are acquired in real time, a requested charging current of the power battery (2) is determined according to the voltage and power, and the output current of the single-stage topology charger (1) is controlled based on the requested charging current.

12. A vehicle, characterized in that: An AC charging circuit as claimed in any one of claims 1 to 9 is employed.

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