Hybrid electric power system and pre-charge method

Abstract

The application discloses a hybrid electric system and a pre-charging method, comprising a main relay, a bidirectional interleaved parallel BOOST converter, a motor system and a generator system; the battery side of the bidirectional interleaved parallel BOOST converter is used for connecting a power battery through the main relay, the bus side of the bidirectional interleaved parallel BOOST converter is connected with the motor system and the generator system; the bus side of the bidirectional interleaved parallel BOOST converter is connected with a bus capacitor; the generator system generates electricity and the motor system consumes electricity to charge the bus capacitor; the bidirectional interleaved parallel BOOST converter works reversely to transmit the energy on the bus capacitor to a first capacitor on the battery side of the bidirectional interleaved parallel BOOST converter; when the voltage at both ends of the main relay is consistent, the main relay is closed, the battery side is connected with the power battery, and current impact is avoided. The pre-charging circuit is saved, the number of components is reduced, the volume is reduced, and the cost is reduced.

Description

Technical Field

[0001] This application relates to the field of electric vehicle technology, specifically to a hybrid electric system and a pre-charging method. Background Technology

[0002] The hybrid electric system includes a bidirectional interleaved parallel boost converter. The battery side of the bidirectional interleaved parallel boost converter connects to the power battery, while the bus side connects to the generator system and the electric motor system. The topology of the bidirectional interleaved parallel boost converter reduces the current load on components, improves system redundancy, and reduces voltage and current ripple under the same hardware parameters and switching frequencies. The boost function of the bidirectional interleaved parallel boost converter can reduce the number of battery cells connected in series, achieving miniaturization and weight reduction of the on-board power supply.

[0003] When the electric motor system is in electric mode, the generator system and the power supply system work together to power the electric motor system to drive the vehicle or other mechanical rotating equipment. When the electric motor system is in regenerative braking mode, the energy fed back by the electric motor system charges the battery through a bidirectional interleaved parallel BOOST converter. In this case, the generator system can either operate in generator mode and work together with the electric motor system to power the battery, or the generator system can be off and the electric motor system can power the battery alone.

[0004] Electric vehicles typically have large capacitors connected to their electrical input terminals. Therefore, a pre-charging circuit is usually added to the main relay between the power battery and the electrical equipment to gradually charge the capacitor before closing the main relay. In existing technologies, the pre-charging branch and the bidirectional interleaved parallel BOOST converter in hybrid electric systems are separate, resulting in numerous components, large size, high cost, and complex control. Summary of the Invention

[0005] In view of this, this application provides a hybrid electric system and a pre-charging method that can pre-charge the capacitor without increasing the pre-charging circuit, thus reducing the number of components.

[0006] This application provides a hybrid electric system, including: a main relay, a bidirectional interleaved parallel BOOST converter, an electric motor system, and a generator system;

[0007] The battery side of the bidirectional interleaved parallel BOOST converter is used to connect the power battery through the main relay, and the bus side of the bidirectional interleaved parallel BOOST converter is connected to the motor system and the generator system.

[0008] The bus side of the bidirectional interleaved parallel BOOST converter is connected to the bus capacitor;

[0009] The generator system generates electricity and the motor system consumes electricity to charge the bus capacitor.

[0010] The bidirectional interleaved parallel BOOST converter operates in reverse, transferring energy from the bus capacitor to the first capacitor on the battery side of the bidirectional interleaved parallel BOOST converter; the main relay closes only when the voltages across the main relay are consistent, so that the battery side of the bidirectional interleaved parallel BOOST converter is connected to the power battery.

[0011] Preferably, it further includes: a second capacitor;

[0012] The second capacitor is connected in parallel with the first capacitor, and the input terminal of the electrical equipment is connected to the second capacitor.

[0013] The bidirectional interleaved parallel BOOST converter is also used to work in reverse to transfer energy from the bus capacitor to the second capacitor. The main relay closes only when the voltage of the second capacitor rises to the voltage of the power battery, so that electrical equipment can be connected to the power battery.

[0014] Preferably, it further includes: a voltage detection circuit and a controller;

[0015] A voltage detection circuit is used to detect the voltage of the power battery and the voltage of the first capacitor;

[0016] The controller is used to control the main relay to close when the difference between the voltage of the power battery and the voltage of the first capacitor is within a preset range.

[0017] Preferably, it further includes: a voltage detection circuit and a controller;

[0018] Voltage detection circuit, used to detect the voltage of the power battery and the voltage of the second capacitor;

[0019] The controller is used to close the main relay when the voltage difference between the power battery and the second capacitor is within a preset range.

[0020] Preferably, the generator system generates electricity and the motor system consumes electricity to charge the bus capacitor to a preset bus voltage, and the bidirectional interleaved parallel BOOST converter operates in reverse.

[0021] This application also provides a pre-charging method for a hybrid electric system, the hybrid electric system including: a main relay, a bidirectional interleaved parallel BOOST converter, a motor system and a generator system; the battery side of the bidirectional interleaved parallel BOOST converter is used to connect to the power battery through the main relay, the bus side of the bidirectional interleaved parallel BOOST converter is connected to the motor system and the generator system; the bus side of the bidirectional interleaved parallel BOOST converter is connected to the bus capacitor.

[0022] The method includes:

[0023] The generator system generates electricity and the motor system consumes electricity to charge the bus capacitor.

[0024] The bidirectional interleaved parallel BOOST converter operates in reverse to transfer the energy from the bus capacitor to the first capacitor on the battery side of the bidirectional interleaved parallel BOOST converter.

[0025] The main relay closes only when the voltages across it are equal, so that the input of the bidirectional interleaved parallel BOOST converter can be connected to the power battery.

[0026] Preferably, the hybrid electric system further includes: a second capacitor; the second capacitor is connected in parallel with the first capacitor, and the input terminal of the electrical device is connected to the second capacitor;

[0027] The method also includes:

[0028] The bidirectional interleaved parallel BOOST converter operates in reverse to transfer energy from the bus capacitor to the second capacitor. When the voltage of the second capacitor rises to the voltage of the power battery, the main relay closes to allow the electrical equipment to connect to the power battery.

[0029] Preferably, the main relay closes only when the voltage of the first capacitor rises to the voltage of the power battery, specifically including:

[0030] When the voltage difference between the power battery and the first capacitor is within a preset range, the main relay closes.

[0031] Preferably, the main relay closes only when the voltage of the second capacitor rises to the voltage of the power battery, specifically including:

[0032] When the voltage difference between the power battery and the second capacitor is within a preset range, the main relay is controlled to close.

[0033] Preferably, the bidirectional interleaved parallel BOOST converter operates in reverse, specifically including:

[0034] The generator system generates electricity and the motor system consumes electricity to charge the bus capacitor to the preset bus voltage, and the bidirectional interleaved parallel BOOST converter then operates in reverse.

[0035] Therefore, this application has the following beneficial effects:

[0036] The hybrid electric system provided in this application includes: a main relay, a bidirectional interleaved parallel BOOST converter, a motor system, and a generator system. The motor system and generator system charge the bus capacitor. The bidirectional interleaved parallel BOOST converter operates in reverse, providing energy from the bus capacitor to the battery-side capacitor, thereby reducing the voltage across the main relay. When the voltage across the main relay is equal, the main relay closes, preventing current surges. Furthermore, this technical solution eliminates the need for a pre-charge circuit, reduces the number of components, shrinks the size, and lowers costs. Attached Figure Description

[0037] Figure 1 A schematic diagram of a hybrid electric system provided in this application embodiment;

[0038] Figure 2 This is a schematic diagram of a pre-charge circuit in a traditional hybrid electric system.

[0039] Figure 3 A schematic diagram of a hybrid electric system provided in this application embodiment;

[0040] Figure 4 A schematic diagram of yet another hybrid electric system provided in this application embodiment;

[0041] Figure 5 A flowchart illustrating a pre-charging method for a hybrid electric system provided in this application embodiment. Detailed Implementation

[0042] To enable those skilled in the art to better understand the technical solutions provided in the embodiments of this application, the application scenarios are first described below with reference to the accompanying drawings. This application takes the field of hybrid electric vehicles as an example.

[0043] See Figure 1 The figure is a schematic diagram of a hybrid electric system provided in an embodiment of this application.

[0044] The hybrid electric system includes: a bidirectional interleaved parallel BOOST converter, an electric motor system MS2, and a generator system MS1;

[0045] The bidirectional interleaved parallel BOOST converter includes: a first inductor L1, a second inductor L2, a first switch S1, a second switch S2, a third switch S3, and a fourth switch S4;

[0046] The first terminal of the first inductor L1 and the first terminal of the second inductor L2 are both used to connect to the positive terminal of the power battery. The second terminal of the first inductor L1 is connected to the first terminal of the bus capacitor Cbus through the second switch S2. The second terminal of the second inductor L2 is connected to the first terminal of the bus capacitor Cbus through the third switch S3. The first switch S1 is connected between the second terminal of the first inductor L1 and the negative terminal of the power battery. The fourth switch S4 is connected between the second terminal of the second inductor L2 and the negative terminal of the power battery.

[0047] The battery side of the bidirectional interleaved parallel BOOST converter is connected to the first capacitor C1, and also to the power battery.

[0048] The bus side of the bidirectional interleaved parallel BOOST converter is connected to MS1 and MS2. When MS2 is in electric mode: MS1 and the power system jointly supply power to system MS2 to drive the vehicle or other mechanical rotating equipment; when MS2 is in regenerative braking mode, the energy fed back by the MS2 system charges the battery through the bidirectional interleaved parallel BOOST converter. At this time, MS1 can either work in generator mode and jointly supply power to the battery with MS2, or it can not work and supply power to the battery alone through MS2.

[0049] The pre-charge circuit of the power battery is described below with reference to the attached diagram.

[0050] See Figure 2 The figure shows a schematic diagram of a pre-charge circuit in a traditional hybrid electric system.

[0051] In a traditional hybrid electric system 400, a pre-charge circuit 200 is connected between the power battery BAT and the battery side of the bidirectional interleaved parallel BOOST converter. In actual products, the pre-charge circuit 200 is quite complex. For ease of explanation, the following explanation will be provided. Figure 2 The precharge circuit 200 is simply represented by a single resistor in the illustration.

[0052] When the hybrid electric system starts working, it is first charged by the pre-charge circuit 200, which charges the capacitor at the input terminal of the electrical equipment 300, and at the same time charges the capacitor on the battery side of the bidirectional interleaved parallel BOOST converter in the hybrid electric system. When the voltage on the capacitor is equal to the voltage of the power battery, the main relay K is closed to avoid a large current surge caused by closing the main relay K directly without pre-charging.

[0053] However, the precharge circuit 200 generally has more components, a larger size, and a higher cost.

[0054] Therefore, to solve the above-mentioned technical problems, this application provides a technical solution that utilizes a motor system and a generator system to charge the bus capacitor. A bidirectional, interleaved, parallel BOOST converter operates in reverse, providing the energy of the bus capacitor to the battery-side capacitor, thereby reducing the voltage across the main relay. When the voltage across the main relay is equal, the main relay is closed, preventing current surges. Furthermore, this technical solution eliminates the need for a pre-charge circuit, reduces the number of components, shrinks the size, and lowers costs.

[0055] To make the above-mentioned objectives, features and advantages of this application more apparent and understandable, the embodiments of this application will be further described in detail below with reference to the accompanying drawings and specific implementation methods.

[0056] See Figure 3 The figure is a schematic diagram of a hybrid electric system provided in an embodiment of this application.

[0057] The hybrid electric system provided in this embodiment includes: a main relay K, a bidirectional interleaved parallel BOOST converter 401, a generator system MS1, and a motor system MS2;

[0058] The battery side of the bidirectional interleaved parallel BOOST converter 401 is used to connect the power battery BAT through the main relay K, and the bus side of the bidirectional interleaved parallel BOOST converter 401 is connected to the motor system MS2 and the generator system MS1.

[0059] The bus side of the bidirectional interleaved parallel BOOST converter 401 is connected to the bus capacitor Cbus;

[0060] The generator system MS1 generates electricity and the motor system MS2 consumes electricity to charge the bus capacitor Cbus.

[0061] The bidirectional interleaved parallel BOOST converter 401 operates in reverse, transferring energy from the bus capacitor Cbus to the first capacitor C1 on the battery side of the bidirectional interleaved parallel BOOST converter 401; the main relay K closes only when the voltages across it are consistent, so that the battery side of the bidirectional interleaved parallel BOOST converter 401 is connected to the power battery.

[0062] It should be understood that the hybrid electric system provided in this application embodiment may further include an electrical device 300, the input terminal of which is connected to a second capacitor C2, i.e., C1 and C2 are connected in parallel. When the bidirectional interleaved parallel BOOST converter 401 operates in reverse to transfer energy from the bus capacitor Cbus to the first capacitor C1, it also transfers energy to the second capacitor C2. Therefore, the voltage across the main relay K can detect the voltage on the first capacitor C1 and also the voltage on the second capacitor C2.

[0063] The hybrid electric system provided in this embodiment does not include a pre-charge circuit. It uses a generator system, a motor system, and a bidirectional interleaved parallel BOOST converter 401 for pre-charging. The main relay is controlled to close only when the voltage across the main relay is equalized, thereby avoiding current surges. Moreover, without a pre-charge circuit, the number of components can be reduced, the size can be minimized, and the cost can be lowered.

[0064] The hybrid electric system provided in this application embodiment further includes: a second capacitor C2;

[0065] The second capacitor C2 is connected in parallel with the first capacitor C1, and the input terminal of the electrical equipment is connected to the second capacitor C2.

[0066] The bidirectional interleaved parallel BOOST converter 401 is also used to work in reverse to transfer the energy on the bus capacitor Cbus to the second capacitor C2. When the voltage of the second capacitor C2 rises to the voltage of the power battery BAT, the main relay K closes so that the electrical equipment 300 can connect the power battery BAT.

[0067] See Figure 4 This figure is a schematic diagram of another hybrid electric system provided in an embodiment of this application.

[0068] The hybrid electric system provided in this application embodiment further includes: a voltage detection circuit (not shown in the figure) and a controller 100;

[0069] MS1 includes a first motor M1, and MS2 includes a second motor M2.

[0070] A voltage detection circuit is used to detect the voltage of the power battery and the voltage of the first capacitor;

[0071] The controller 100 is used to control the main relay K to close when the difference between the voltage of the power battery and the voltage of the first capacitor C1 is within a preset range.

[0072] In addition, a voltage detection circuit is used to detect the voltage of the power battery and the voltage of the second capacitor; the controller 100 is used to control the main relay K to close when the difference between the voltage of the power battery BAT and the voltage of the second capacitor C2 is within a preset range.

[0073] One possible implementation is that the generator system MS1 generates electricity and the motor system MS2 consumes power to charge the bus capacitor Cbus to a preset bus voltage, and the bidirectional interleaved parallel BOOST converter operates in reverse.

[0074] Based on the hybrid electric system provided in the above embodiments, this application also provides a pre-charging method for the hybrid electric system, which will be described in detail below with reference to the accompanying drawings.

[0075] See Figure 5 The figure is a flowchart of a pre-charging method for a hybrid electric system provided in an embodiment of this application.

[0076] The pre-charging method for a hybrid electric system provided in this embodiment includes: a main relay, a bidirectional interleaved parallel BOOST converter, a motor system, and a generator system; the battery side of the bidirectional interleaved parallel BOOST converter is used to connect to the power battery through the main relay, the bus side of the bidirectional interleaved parallel BOOST converter is connected to the motor system and the generator system; and the bus side of the bidirectional interleaved parallel BOOST converter is connected to the bus capacitor.

[0077] The method includes:

[0078] S501: The generator system generates electricity and the motor system consumes electricity to charge the bus capacitor;

[0079] S501: The bidirectional interleaved parallel BOOST converter operates in reverse to transfer the energy on the bus capacitor to the first capacitor on the battery side of the bidirectional interleaved parallel BOOST converter.

[0080] S501: The main relay closes only when the voltages at both ends are equal, so that the input of the bidirectional interleaved parallel BOOST converter can be connected to the power battery.

[0081] The hybrid electric system also includes: a second capacitor; the second capacitor is connected in parallel with the first capacitor, and the input terminal of the electrical equipment is connected to the second capacitor;

[0082] The method also includes:

[0083] The bidirectional interleaved parallel BOOST converter operates in reverse to transfer energy from the bus capacitor to the second capacitor. When the voltage of the second capacitor rises to the voltage of the power battery, the main relay closes to allow the electrical equipment to connect to the power battery.

[0084] Since the first capacitor and the second capacitor are connected in parallel, the energy transferred from the bus capacitor to the first capacitor is simultaneously transferred to the second capacitor. This application does not specifically limit whether the voltage of the first capacitor is compared with the voltage of the power battery, or whether the voltage of the second capacitor is compared with the voltage of the power battery.

[0085] One possible implementation is that the main relay closes only when the voltage of the first capacitor rises to the voltage of the power battery, specifically including:

[0086] When the voltage difference between the power battery and the first capacitor is within a preset range, the main relay closes.

[0087] One possible implementation is that the main relay closes only when the voltage of the second capacitor rises to the voltage of the power battery, specifically including:

[0088] When the voltage difference between the power battery and the second capacitor is within a preset range, the main relay is controlled to close.

[0089] The bidirectional interleaved parallel BOOST converter operates in reverse, specifically including:

[0090] The generator system generates electricity and the motor system consumes electricity to charge the bus capacitor to the preset bus voltage, and the bidirectional interleaved parallel BOOST converter then operates in reverse.

[0091] The control method for the hybrid electric system provided in this embodiment controls the operation of the generator system, the motor system, and the bidirectional interleaved parallel BOOST converter. This system does not include a pre-charge circuit. It uses the generator system, the motor system, and the bidirectional interleaved parallel BOOST converter for pre-charging. The main relay is only closed when the voltage across the main relay is equalized, thereby avoiding current surges. Moreover, the absence of a pre-charge circuit reduces the number of components, shrinks the size, and lowers the cost.

[0092] It should be noted that the various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. Similar or identical parts between embodiments can be referred to interchangeably. For the systems or apparatus disclosed in the embodiments, since they correspond to the methods disclosed in the embodiments, the descriptions are relatively simple, and relevant parts can be referred to the method section.

[0093] The above description of the disclosed embodiments enables those skilled in the art to make or use this application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this application. Therefore, this application is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A hybrid electric system, characterized in that, include: Main relays, bidirectional interleaved parallel BOOST converters, motor systems, and generator systems; The battery side of the bidirectional interleaved parallel BOOST converter is used to connect to the power battery through the main relay, and the bus side of the bidirectional interleaved parallel BOOST converter is connected to the motor system and the generator system; The bus side of the bidirectional interleaved parallel BOOST converter is connected to the bus capacitor; The generator system generates electricity and the motor system consumes electricity to charge the bus capacitor; The bidirectional interleaved parallel BOOST converter operates in reverse to transfer the energy from the bus capacitor to the first capacitor on the battery side of the bidirectional interleaved parallel BOOST converter; the main relay closes only when the voltages across the main relay are consistent, so that the battery side of the bidirectional interleaved parallel BOOST converter is connected to the power battery.

2. The system according to claim 1, characterized in that, It also includes: a second capacitor; The second capacitor is connected in parallel with the first capacitor, and the input terminal of the electrical equipment is connected to the second capacitor; The bidirectional interleaved parallel BOOST converter is also used to work in reverse to transfer the energy on the bus capacitor to the second capacitor. When the voltage of the second capacitor rises to the voltage of the power battery, the main relay closes to connect the electrical equipment to the power battery.

3. The system according to claim 1, characterized in that, Also includes: Voltage detection circuit and controller; The voltage detection circuit is used to detect the voltage of the power battery and the voltage of the first capacitor; The controller is used to control the main relay to close when the difference between the voltage of the power battery and the voltage of the first capacitor is within a preset range.

4. The system according to claim 2, characterized in that, Also includes: Voltage detection circuit and controller; The voltage detection circuit is used to detect the voltage of the power battery and the voltage of the second capacitor; The controller is used to control the main relay to close when the difference between the voltage of the power battery and the voltage of the second capacitor is within a preset range.

5. The system according to any one of claims 1-4, characterized in that, The generator system generates electricity and the motor system consumes electricity to charge the bus capacitor to the preset bus voltage, and only then does the bidirectional interleaved parallel BOOST converter operate in reverse.

6. A pre-charging method for a hybrid electric system, characterized in that, The hybrid electric system includes: a main relay, a bidirectional interleaved parallel BOOST converter, a motor system, and a generator system; the battery side of the bidirectional interleaved parallel BOOST converter is used to connect to the power battery through the main relay, and the bus side of the bidirectional interleaved parallel BOOST converter is connected to the motor system and the generator system; the bus side of the bidirectional interleaved parallel BOOST converter is connected to a bus capacitor. The method includes: The generator system generates electricity and the motor system consumes electricity to charge the bus capacitor; The bidirectional interleaved parallel BOOST converter operates in reverse to transfer the energy on the bus capacitor to the first capacitor on the battery side of the bidirectional interleaved parallel BOOST converter; The main relay closes only when the voltages at both ends are consistent, so that the input of the bidirectional interleaved parallel BOOST converter is connected to the power battery.

7. The method according to claim 6, characterized in that, The hybrid electric system further includes: a second capacitor; the second capacitor is connected in parallel with the first capacitor, and the input terminal of the electrical equipment is connected to the second capacitor; The method also includes: The bidirectional interleaved parallel BOOST converter is controlled to operate in reverse to transfer the energy on the bus capacitor to the second capacitor. When the voltage of the second capacitor rises to the voltage of the power battery, the main relay closes to connect the electrical equipment to the power battery.

8. The method according to claim 6, characterized in that, The main relay closes only when the voltage of the first capacitor rises to the voltage of the power battery, specifically including: The main relay closes when the difference between the voltage of the power battery and the voltage of the first capacitor is within a preset range.

9. The method according to claim 7, characterized in that, The main relay closes only when the voltage of the second capacitor rises to the voltage of the power battery, specifically including: When the difference between the voltage of the power battery and the voltage of the second capacitor is within a preset range, the main relay is controlled to close.

10. The method according to any one of claims 6-9, characterized in that, The bidirectional interleaved parallel BOOST converter operates in reverse, specifically including: The generator system generates electricity and the motor system consumes electricity to charge the bus capacitor to the preset bus voltage, and only then does the bidirectional interleaved parallel BOOST converter operate in reverse.

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