Electric vehicle soft switch charging device

Abstract

The application discloses an electric vehicle soft switch charging device which is used for solving the problems of large switch loss and low efficiency of an existing charging device. The device comprises an alternating voltage source, a PFC rectification module, a DC / DC conversion module, a charging module and a charging battery. The DC / DC conversion module comprises a power switch and a diode. The power switch realizes zero-current turn-on and zero-voltage turn-off, and the diode realizes zero-current turn-on and turn-off. By arranging only one power switch, zero-current turn-on and zero-voltage turn-off are realized, the structure is simple, the number of switch devices is small, the volume and cost of the device are reduced, the switch loss of the device is effectively reduced, and the working efficiency of the device is remarkably improved.

Description

Technical Field

[0001] This invention relates to a soft-switching charging device for electric vehicles, belonging to the field of electric vehicle charging. Background Technology

[0002] Automobiles have become an important means of transportation in our lives; however, the pollutants such as carbon monoxide and nitrogen oxides produced by vehicle exhaust seriously affect the human living environment, and global energy depletion is another problem facing humanity. Electric vehicles, using electricity as their power source, will replace gasoline-powered vehicles as the best choice for human travel. In the research and development of electric vehicles, charging circuits and charging control methods have always been hot research topics. Developing high-performance, high-efficiency, and high-power-density chargers will benefit the entire electric vehicle industry.

[0003] Electric vehicle charging devices typically include switching power supplies, with different topologies depending on the application. Soft-switching power supplies are also used in electric vehicle charging circuits, employing full-bridge soft-switching isolation converters. These converters have high core utilization and can achieve high efficiency by utilizing converter parasitic parameters, making them widely used in medium-to-high power applications. Common soft-switching power supplies include full-bridge zero-voltage, full-bridge zero-current, full-bridge zero-current switching, and resonant converters. However, existing charging devices are characterized by numerous switching devices and low efficiency. Summary of the Invention

[0004] This invention proposes a soft-switching charging device for electric vehicles, which aims to solve the problems of high switching losses and low efficiency in existing charging devices.

[0005] It includes an AC voltage source, a PFC rectifier module, a DC / DC converter module, a charging module, and a rechargeable battery;

[0006] An AC voltage source is used to provide AC voltage input to the PFC rectifier module;

[0007] The PFC rectifier module receives AC voltage from an AC voltage source, rectifies and corrects the AC voltage, and provides a first DC voltage.

[0008] The DC / DC converter module is used to receive the first DC voltage and boost the first DC voltage to a second DC voltage, where the second DC voltage is the DC bus voltage.

[0009] The charging module receives the second DC voltage, performs charging control, and outputs the desired charging power and current to the rechargeable battery;

[0010] The DC / DC converter module includes a power switch and a diode. The power switch enables zero-current turn-on and zero-voltage turn-off, and the diode enables zero-current turn-on and turn-off.

[0011] Preferably, the PFC rectifier module includes a first diode, a second diode, a third diode, a fourth diode, a fifth diode, a first inductor, a first power switch, and a first capacitor; wherein, the cathodes of the first and second diodes are connected together and connected to one end of the first inductor, the anodes of the first and second diodes are respectively connected to the cathodes of the third and fourth diodes, and are respectively connected to the two ends of an AC voltage source, and the anodes of the third and fourth diodes are connected together; the other end of the first inductor is connected to the anode of the fifth diode, and the other end of the first inductor is also connected to the drain of the first power switch, the source of the first power switch is connected to the anodes of the third and fourth diodes, the cathode of the fifth diode is connected to one end of the first capacitor, and the other end of the first capacitor is connected to the source of the first power switch.

[0012] Preferably, the DC / DC conversion module includes a second inductor, a third inductor, a fourth inductor, a second power switch, a second capacitor, a third capacitor, a fourth capacitor, an isolation transformer, a fifth diode, and a sixth diode; wherein, the series branch formed by the second inductor, the third inductor, and the second power switch is connected in parallel across the first capacitor; the second inductor is connected in parallel across the primary winding of the isolation transformer; one end of the second inductor is connected to the same-name terminal of the primary winding of the isolation transformer, and the other end is connected to one end of the third inductor; the other end of the third inductor is connected to the drain of the second power switch; the source of the second power switch is connected to the first capacitor; the second capacitor is connected in parallel across the second power switch; the same-name terminal of the secondary winding of the isolation transformer is connected to one end of the fourth inductor; the other end of the fourth inductor is connected to the anode of the fifth diode and the cathode of the fourth capacitor; the other end of the secondary winding of the isolation transformer is connected to one end of the third capacitor; the other end of the third capacitor is connected to the cathode of the fifth diode; the other end of the third capacitor is also connected to the anode of the sixth diode; the cathode of the sixth diode is connected to the positive terminal of the fourth capacitor; and the voltage across the fourth capacitor constitutes the DC bus voltage.

[0013] Preferably, the charging module includes a third power switch, wherein one end of the third power switch is connected to the positive terminal of the fourth capacitor, and the other end is connected to the rechargeable battery.

[0014] The DC / DC converter module proposed in this invention uses soft-switching technology. By setting only one power switch, it achieves zero-current turn-on and zero-voltage turn-off. The structure is simple, fewer switching devices are used, reducing the size and cost of the device, effectively reducing the switching losses of the device, and significantly improving the working efficiency of the device. Attached Figure Description

[0015] Figure 1 : Structural diagram of the charging device of the present invention;

[0016] Figure 2 The circuit structure of the charging device of the present invention;

[0017] Figure 3 The circuit structure of the PFC rectifier module of the charging device of the present invention;

[0018] Figure 4 The circuit structure of the DC / DC converter module of the charging device of the present invention;

[0019] Figure 5 The circuit structure of the charging module of the charging device of the present invention;

[0020] Figure 6 Waveform diagram of the DC / DC conversion module of the charging device of the present invention. Detailed Implementation

[0021] Figure 1 This is a structural diagram of the charging device of the present invention. The electric vehicle soft-switching charging device of the present invention includes an AC voltage source, a PFC rectifier module, a DC / DC converter module, a charging module, and a rechargeable battery. The AC voltage source provides AC voltage input to the PFC rectifier module. The PFC rectifier module receives the AC voltage provided by the AC voltage source, rectifies and corrects the power factor of the AC voltage, and provides a first DC voltage. The DC / DC converter module receives the first DC voltage and boosts it to a second DC voltage, where the second DC voltage is the DC bus voltage. The charging module receives the second DC voltage, performs charging control, and outputs the desired charging power and current to the rechargeable battery. The DC / DC converter module includes a power switch and a diode; the power switch achieves zero-current turn-on and zero-voltage turn-off, and the diode achieves zero-current turn-on and turn-off.

[0022] Figure 2 This is the circuit structure of the charging device of the present invention. Figure 3-5 These are the circuit structures of the PFC rectifier module, DC / DC converter module, and charging module, respectively.

[0023] Figure 3This is a circuit diagram of a PFC rectifier module, which includes a first diode D1, a second diode D2, a third diode D3, a fourth diode D4, a fifth diode D5, a first inductor L1, a first power switch S1, and a first capacitor C1. The cathodes of the first diode D1 and the second diode D2 are connected together and to one end of the first inductor L1. The anodes of the first diode D1 and the second diode D2 are connected to the cathodes of the third diode D3 and the fourth diode D4, respectively, and are connected to the two ends of an AC voltage source. The anodes of the third diode D3 and the fourth diode D4 are connected together. The other end of the first inductor L1 is connected to the anode of the fifth diode D5 and also to the drain of the first power switch S1. The source of the first power switch S1 is connected to the anodes of the third diode D3 and the fourth diode D4. The cathode of the fifth diode D5 is connected to one end of the first capacitor C1, and the other end of the first capacitor C1 is connected to the source of the first power switch S1. Of course, the PFC rectifier module can also be other forms of existing PFC circuits.

[0024] Figure 4 This is the circuit structure of the DC / DC converter module of the charging device of the present invention. The DC / DC converter module includes a second inductor L2, a third inductor L3, a fourth inductor L4, a second power switch S2, a second capacitor C2, a third capacitor C3, a fourth capacitor C4, an isolation transformer T, a fifth diode D5, and a sixth diode D6. The series branch formed by the second inductor L2, the third inductor L3, and the second power switch S2 is connected in parallel across the first capacitor C1. The second inductor L2 is connected in parallel across the primary winding of the isolation transformer T. One end of the second inductor L2 is connected to the corresponding terminal of the primary winding of the isolation transformer T, and the other end is connected to one end of the third inductor L3. The other end of the third inductor L3 is connected to the second power switch S2. The drain and source of the second power switch S2 are connected to the first capacitor C1. The second capacitor C2 is connected in parallel across the two ends of the second power switch S2. The same-name terminal of the secondary winding of the isolation transformer T is connected to one end of the fourth inductor L4. The other end of the fourth inductor L4 is connected to the anode of the fifth diode D5 and the cathode of the fourth capacitor C4. The other end of the secondary winding of the isolation transformer T is connected to one end of the third capacitor C3. The other end of the third capacitor C3 is connected to the cathode of the fifth diode D5. The other end of the third capacitor C3 is also connected to the anode of the sixth diode D6. The cathode of the sixth diode D6 is connected to the positive terminal of the fourth capacitor C4. The voltage across the fourth capacitor C4 constitutes the DC bus voltage.

[0025] The working principle of the DC / DC converter module is as follows: Figure 6 The waveform diagram is used for illustration. To minimize switching losses, the DC / DC converter module uses only one power switch, namely the second power switch S2. The second power switch S2 has a fixed switching period, T. s=1 / f s , where f s The switching frequency is given. The DC / DC converter module uses only one isolation transformer T, with a turns ratio n = N2 / N1. When the second power switch S2 is off, the second capacitor C2 resonates with the second inductor L2 and the third inductor L3, thus achieving zero-voltage turn-off for the second power switch S2. When the second power switch S2 is off, the second capacitor C2, the second inductor L2, and the third inductor L3 form a series resonant energy storage system, reducing the inductor current to zero before the second power switch S2 turns on, thus achieving zero-current turn-on for the second power switch S2. By properly setting the capacitance of the second capacitor C2, the second power switch S2 can achieve both zero-voltage turn-off and zero-current turn-on, thereby minimizing the switching losses of the second power switch S2.

[0026] See Figure 6 The time from t0 to t3 is one switching cycle T. s The second power switch S2 is turned on for a period of time from t0 to t2, denoted as T. on The time during which the second power switch S2 is turned off is from t2 to t3, denoted as T. off The duty cycle D of the second power switch S2 s2 =t on / T s The waveform of one cycle is divided into three stages: [t0, t1], [t1, t2], and [t2, t3].

[0027] During the [t0, t1] phase, the second power switch S2 is turned on, and the current flowing through it rises rapidly. The current flowing through the fifth diode D5 on the secondary side of the isolation transformer T follows a sinusoidal curve within [t0, t1] until it drops to zero again at time t1. During the [t1, t2] phase, since the current in the fifth diode D5 has already dropped to zero at time t1, zero-current turn-off can be achieved. During the [t2, t3] phase, the second power switch S2 is turned off at time t2. Due to the setting of the second capacitor C2, the second power switch S2 achieves zero-voltage turn-off. At this time, the current of the second power switch S2 drops rapidly to zero, and the sixth diode D6 on the secondary side of the isolation transformer T is turned on. Due to the resonance formed by the second inductor L2 and the third inductor L3, the current flowing through the sixth diode D6 rises rapidly. At this time, the secondary winding of the isolation transformer T, the third inductor C3, the sixth diode D6, the fourth capacitor C4, and the fourth inductor L4 form a circuit, and the energy stored in the third inductor C3 charges the fourth capacitor C4. At time t3, the current flowing through the second inductor L2 drops to zero, preparing for zero-current turn-on in the next cycle. Simultaneously, the current flowing through the sixth diode D6 will also be zero, enabling zero-current turn-off. Thus, the second power switch S2 achieves zero-current turn-on and zero-voltage turn-off, while the fifth diode D5 and the sixth diode D6 achieve zero-current turn-on and turn-off.

[0028] The boost ratio of the DC / DC converter module is:

[0029]

[0030] To obtain the desired DC bus voltage V C4 The duty cycle D of the second power switch S2 is continuously adjusted. S2 It is simple to control, requires few switching devices, has low switching losses, and is highly efficient.

[0031] Figure 5 The circuit structure of the charging module for the charging device is described. The charging module includes a third power switch S3, one end of which is connected to the positive terminal of the fourth capacitor C4, and the other end is connected to the rechargeable battery. Of course, the charging module can also be other existing types of charging modules.

[0032] The DC / DC converter module proposed in this invention uses soft-switching technology. By setting only one power switch, it achieves zero-current turn-on and zero-voltage turn-off. The structure is simple, fewer switching devices are used, reducing the size and cost of the device, effectively reducing the switching losses of the device, and significantly improving the working efficiency of the device.

[0033] Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0034] Those skilled in the art will understand that embodiments of this application can be provided as methods, systems, or computer program products. Therefore, this application can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, this application can take the form of a computer program product embodied on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0035] This application is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of this application. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart... Figure 1One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0036] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0037] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0038] The above are merely embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention are included within the scope of the claims of the present invention pending approval.

Claims

1. A soft-switching charging device for electric vehicles, comprising an AC voltage source, a PFC rectifier module, a DC / DC converter module, a charging module, and a rechargeable battery; An AC voltage source is used to provide AC voltage input to the PFC rectifier module; The PFC rectifier module receives AC voltage from an AC voltage source, rectifies and corrects the AC voltage, and provides a first DC voltage. The DC / DC converter module is used to receive the first DC voltage and boost the first DC voltage to a second DC voltage, where the second DC voltage is the DC bus voltage. The charging module receives the second DC voltage, performs charging control, and outputs the desired charging power and current to the rechargeable battery; The DC / DC conversion module is characterized by comprising a power switch and a diode, wherein the power switch achieves zero-current turn-on and zero-voltage turn-off, and the diode achieves zero-current turn-on and turn-off; the DC / DC conversion module includes a second inductor, a third inductor, a fourth inductor, a second power switch, a second capacitor, a third capacitor, a fourth capacitor, an isolation transformer, a fifth diode, and a sixth diode; wherein, a series branch consisting of the second inductor, the third inductor, and the second power switch is connected in parallel across the first capacitor, the second inductor is connected in parallel across the primary winding of the isolation transformer, and one end of the second inductor is connected to the corresponding terminal of the primary winding of the isolation transformer, and the other... One end of the third inductor is connected to one end of the third inductor, and the other end of the third inductor is connected to the drain of the second power switch. The source of the second power switch is connected to the first capacitor, and the second capacitor is connected in parallel across the second power switch. The same-name terminal of the secondary winding of the isolation transformer is connected to one end of the fourth inductor, and the other end of the fourth inductor is connected to the anode of the fifth diode and the cathode of the fourth capacitor. The other end of the secondary winding of the isolation transformer is connected to one end of the third capacitor, and the other end of the third capacitor is connected to the cathode of the fifth diode. The other end of the third capacitor is also connected to the anode of the sixth diode, and the cathode of the sixth diode is connected to the positive terminal of the fourth capacitor. The voltage across the fourth capacitor constitutes the DC bus voltage.

2. The electric vehicle soft-switching charging device as described in claim 1, characterized in that, The PFC rectifier module includes a first diode, a second diode, a third diode, a fourth diode, a fifth diode, a first inductor, a first power switch, and a first capacitor. The cathodes of the first and second diodes are connected together and to one end of the first inductor. The anodes of the first and second diodes are connected to the cathodes of the third and fourth diodes, respectively, and are connected to both ends of an AC voltage source. The anodes of the third and fourth diodes are also connected. The other end of the first inductor is connected to the anode of the fifth diode and simultaneously to the drain of the first power switch. The source of the first power switch is connected to the anodes of the third and fourth diodes. The cathode of the fifth diode is connected to one end of the first capacitor, and the other end of the first capacitor is connected to the source of the first power switch.

3. The electric vehicle soft-switching charging device as described in claim 2, characterized in that, The charging module includes a third power switch, one end of which is connected to the positive terminal of the fourth capacitor and the other end is connected to the rechargeable battery.

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