A powertrain system based on a modular multilevel converter

Abstract

The present application provides a powertrain system based on a modular multilevel converter, including: an AC first port, an AC second port, a plurality of parallel-connected phase circuits, a DC first port, a DC second port, an auxiliary controller, and a main controller. Each phase circuit includes: an upper bridge arm circuit and a lower bridge arm circuit, wherein the second end of the upper bridge arm circuit is cascaded with the first end of the lower bridge arm circuit; both the upper bridge arm circuit and the lower bridge arm circuit include a plurality of cascaded arm sub-modules and arm inductors. Each arm sub-module includes: a capacitor, a battery pack, and a plurality of switching tubes. The plurality of switching tubes and the capacitor form a full-bridge circuit, and the capacitor is connected in parallel with the battery pack. The auxiliary controller detects the state information of each battery in the battery pack, and based on the detected state information of each battery, realizes the remaining power balance control of each battery in the battery pack by means of a bypass resistor. It can effectively improve the power balance between the arm sub-modules.

Description

Technical Field

[0001] The present application relates to the technical field of new energy, and more specifically, to a powertrain system based on a modular multilevel converter (MMC). Background Art

[0002] The existing powertrain system based on a modular multilevel converter adopts a three-phase six-arm structure with multiple sub-modules cascaded (connected in series). Each phase includes upper and lower arm circuits composed of multiple arm sub-modules cascaded. In this way, it can ensure that the powertrain system outputs a waveform of higher quality. At the same time, the modular structure is relatively simple, and manufacturing and assembly are convenient.

[0003] Currently, for a powertrain system based on a modular multilevel converter, the output power of the powertrain system is the superposition of the output powers of each arm sub-module. However, when each arm sub-module outputs power, there may be different differences in the output voltage and output current, resulting in possible mismatches in the remaining powers of each arm sub-module, making the power balance among the arm sub-modules poor. And the arm sub-module with a lower remaining power will directly reduce the overall performance of each phase-level converter, thus forming a "short-board effect" and reducing the service life of the batteries in the arm sub-module. Summary of the Invention

[0004] In view of this, the purpose of the present application is to provide a powertrain system based on a modular multilevel converter, which is used to solve the problems of poor power balance among arm sub-modules and poor battery balancing ability in a traditional powertrain system in the prior art.

[0005] In a first aspect, an embodiment of the present application provides a powertrain system based on a modular multilevel converter. The powertrain system includes:

[0006] An AC first port, an AC second port, multiple parallel phase circuits, a DC first port, a DC second port, an auxiliary controller, and a main controller. Each phase circuit includes: an upper arm circuit and a lower arm circuit, where the second end of the upper arm circuit is cascaded with the first end of the lower arm circuit;

[0007] The AC first port is connected between the second end of the upper arm circuit and the first end of the lower arm circuit through a first switch, and outputs power to or inputs power from a first external AC device;

[0008] The AC second port is connected between the second end of the upper arm circuit and the first end of the lower arm circuit through an inverter inductor and a second switch, and outputs power to or inputs power from a second external AC device;

[0009] The DC first port is connected between the first end of the upper bridge arm circuit and the second end of the lower bridge arm circuit through the third switch and the bidirectional DC / DC circuit, and outputs power to the external first DC device or inputs power from the first DC device;

[0010] The DC second port is connected between the first end of the upper bridge arm circuit and the second end of the lower bridge arm circuit through the fourth switch, and outputs power to the external second DC device or inputs power from the second DC device;

[0011] Both the upper bridge arm circuit and the lower bridge arm circuit include a plurality of cascaded bridge arm sub-modules and bridge arm inductors. Each bridge arm sub-module includes: a capacitor, a battery pack, and a plurality of switching tubes. The plurality of switching tubes and the capacitor form a full-bridge circuit, and the capacitor is connected in parallel with the battery pack;

[0012] The auxiliary controller is used to detect the state information of each battery in the battery pack, and based on the detected state information of each battery, achieve the remaining power balance control of each battery in the battery pack by means of a bypass resistor. Based on the state information of each battery, obtain the power information of the battery pack and output it to the main controller;

[0013] The main controller is used to detect the power information of the AC first port, the AC second port, the DC first port, and the DC second port. Based on the detected power information and the power information uploaded by the auxiliary controller, respectively determine the balance power information of each bridge arm sub-module and output it to the corresponding auxiliary controller, so that the auxiliary controller generates a control signal for controlling the on and off duration of the switching tubes in the bridge arm sub-module according to the obtained power information of the battery pack and the balance power information, so as to balance the remaining power of each bridge arm sub-module.

[0014] Optionally, the upper bridge arm circuit includes a plurality of upper bridge arm sub-modules and an upper bridge arm inductor connected in series in sequence; the lower bridge arm circuit includes a plurality of lower bridge arm sub-modules and a lower bridge arm inductor connected in series in sequence;

[0015] The AC first port is connected between the upper bridge arm inductor and the lower bridge arm inductor through the first switch;

[0016] One end of the AC second port is connected to the inverter inductor, and the other end is connected between the upper bridge arm inductor and the lower bridge arm inductor through the second switch.

[0017] Optionally, the bridge arm sub-module includes: a first switching tube, a second switching tube, a third switching tube, a fourth switching tube, a first capacitor, a first diode, a second diode, a third diode, a fourth diode, and a battery pack, where,

[0018] The collector of the first switching tube is respectively connected to the collector of the second switching tube, the negative electrode of the first diode, one end of the first capacitor, and the positive electrode of the battery pack;

[0019] The emitter of the first switching transistor is respectively connected to the collector of the third switching transistor and the anode of the first diode;

[0020] The emitter of the third switching transistor is respectively connected to the emitter of the fourth switching transistor, the anode of the third diode, the other end of the first capacitor, and the negative electrode of the battery pack;

[0021] The cathode of the third diode is connected to the collector of the third switching transistor;

[0022] The emitter of the second switching transistor is respectively connected to the collector of the fourth switching transistor and the anode of the second diode;

[0023] The cathode of the second diode is connected to the collector of the second switching transistor;

[0024] The cathode of the fourth diode is connected to the collector of the fourth switching transistor, and the anode is connected to the emitter of the fourth switching transistor;

[0025] The bases of the first switching transistor, the second switching transistor, the third switching transistor, and the fourth switching transistor are connected to a control signal;

[0026] The emitter of the first switching transistor serves as the first end of the cascaded bridge arm sub-module, and the emitter of the second switching transistor serves as the second end of the cascaded bridge arm sub-module and is connected to the first end of the next cascaded bridge arm sub-module.

[0027] Optionally, when the bridge arm current direction points to the connection point of the first switching transistor and the third switching transistor, the first switching transistor and the fourth switching transistor are turned on to charge the battery pack, the second switching transistor and the third switching transistor are turned on to discharge the battery pack, the first switching transistor and the second switching transistor are turned on, or the third switching transistor and the fourth switching transistor are turned on to isolate the bridge arm sub-module.

[0028] Optionally, the bridge arm sub-module further includes:

[0029] Bipolar diodes, including a fifth diode and a sixth diode, which are reversely connected in series. Among them, the anode of the fifth diode is connected to the first end of the bridge arm sub-module, the cathode of the fifth diode is connected to the cathode of the sixth diode, and the anode of the sixth diode is connected to the second end of the bridge arm sub-module.

[0030] Optionally, the battery pack includes a plurality of cascaded battery modules, and each battery module includes a plurality of parallel-connected batteries.

[0031] Optionally, it further includes: a second capacitor and a third capacitor, where,

[0032] The second capacitor is connected in series with the third capacitor. One end of the second capacitor is connected to the first end of the upper bridge arm circuit, the other end is connected to one end of the third capacitor, the other end of the third capacitor is connected to the second end of the lower bridge arm circuit, and the other end of the second capacitor and one end of the third capacitor are grounded.

[0033] Optionally, it further includes:

[0034] A DC third port, including: a fifth switch, a unidirectional DC / DC circuit, a reverse diode, and a photovoltaic array, where

[0035] The first end of the fifth switch is connected to the first end of the upper bridge arm circuit, the second end is connected to the second end of the lower bridge arm circuit, the third end is connected to the first output end of the unidirectional DC / DC circuit, and the fourth end is connected to the second output end of the unidirectional DC / DC circuit;

[0036] The first input end of the unidirectional DC / DC circuit is connected to the negative electrode of the reverse diode;

[0037] The positive electrode of the reverse diode is connected to the first output end of the photovoltaic array;

[0038] The second output end of the photovoltaic array is connected to the second input end of the unidirectional DC / DC circuit.

[0039] Optionally, the auxiliary controller includes: a communication unit, a processor, a driving unit, a sampling unit, and an equalizing unit, where

[0040] The communication unit is connected to the processor, and the processor is also respectively connected to the driving unit, the sampling unit, and the equalizing unit. The sampling unit and the equalizing unit are also respectively connected to each battery in the battery pack.

[0041] The sampling unit is used to sample the state information of each battery in the battery pack and output the sampled state information of the battery to the processor;

[0042] The processor receives the state information of each battery output by the sampling unit, obtains the power-abnormal batteries in the battery pack that are higher than the preset power threshold, and notifies the equalizing unit to achieve power balance of each battery in the battery pack by connecting a high-value bypass resistor in parallel across the two poles of the power-abnormal battery;

[0043] According to the detected state information of each battery, calculate the power information of the bridge arm sub-module, and report the calculated power information of the bridge arm sub-module to the main controller through the communication unit;

[0044] Receive the equalizing power information sent by the main controller through the communication unit and output it to the driving unit;

[0045] The drive unit receives the balanced power information, generates a control signal for balancing the remaining power of the arm sub-module based on the power information of the arm sub-module and the balanced power information, and uses the control signal to control the on-off duration of the switching tubes in the arm sub-module, so as to balance the remaining power of each arm sub-module.

[0046] Optionally, the number of the powertrain systems is 2. The two powertrain systems are connected through the second DC port to achieve mutual charging. The two powertrain systems respectively realize the charge and discharge of the batteries in the corresponding arm sub-modules through the switching tubes in their respective arm sub-modules.

[0047] A powertrain system based on a modular multilevel converter provided by an embodiment of the present application determines the balanced power information of each arm sub-module respectively by setting a total controller to detect the power information of each port and based on the detected power information and the power information of the battery pack uploaded by the auxiliary controller, and enables the auxiliary controller to generate a control signal for balancing the remaining power of the arm sub-module based on the power information of the battery pack and the balanced power information, so as to control the on-off of the switching tubes in the corresponding arm sub-module by using the control signal to control the remaining power of the arm sub-module; meanwhile, the auxiliary controller realizes the balanced control of the remaining power of each battery in the battery pack by means of a bypass resistor according to the detected state information of each battery. In this way, the power balance between the arm sub-modules and the batteries in the arm sub-module can be achieved without modifying the circuit structure of the powertrain system, the battery balance ability in the powertrain system is improved, the output of the powertrain system is stabilized, the stability of the operation of the powertrain system is improved, and the service life and use efficiency of the power components in the powertrain system are effectively improved.

[0048] To make the above objects, features, and advantages of the present application more obvious and understandable, the following specific embodiments are given in conjunction with the accompanying drawings and are described in detail as follows. Description of the Drawings

[0049] To more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required to be used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present application and should not be regarded as limiting the scope. For those of ordinary skill in the art, other relevant drawings can be obtained based on these drawings without creative efforts.

[0050] Figure 1 It is a schematic structural diagram of a powertrain system based on a modular multilevel converter provided by an embodiment of the present application;

[0051] Figure 2 It is a schematic structural diagram of an arm sub-module provided by an embodiment of the present application;

[0052] Figure 3 Schematic diagram of the battery pack structure provided by the embodiment of the present application;

[0053] Figure 4 Schematic diagram of the connection structure between the main controller and the auxiliary controller provided by the embodiment of the present application;

[0054] Figure 5 Schematic diagram of the auxiliary controller structure provided by the embodiment of the present application. Detailed implementation manners

[0055] To make the objectives, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present application. Apparently, the described embodiments are only a part rather than all of the embodiments of the present application. Usually, the components of the embodiments of the present application described and illustrated in the accompanying drawings here can be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present application provided in the accompanying drawings is not intended to limit the scope of the present application to be protected, but merely represents the selected embodiments of the present application. Based on the embodiments of the present application, all other embodiments obtained by those skilled in the art without creative efforts shall fall within the protection scope of the present application.

[0056] Figure 1 Schematic diagram of the powertrain system structure based on a modular multilevel converter provided by the embodiment of the present application. As Figure 1 shown, the powertrain system includes: an AC first port 11, an AC second port 12, a plurality of parallel-connected phase circuits 13, a DC first port 14, a DC second port 15, an auxiliary controller (not shown in the figure) and a main controller (not shown in the figure). Among them, each phase circuit 13 includes: an upper arm circuit and a lower arm circuit, where the second end of the upper arm circuit is cascaded with the first end of the lower arm circuit;

[0057] The AC first port 11 is connected between the second end of the upper arm circuit and the first end of the lower arm circuit through a first switch (S1) to output power to or input power from an external first AC device;

[0058] The AC second port 12 is connected between the second end of the upper arm circuit and the first end of the lower arm circuit through an inverter inductor (Lac) and a second switch (S2) to output power to or input power from an external second AC device;

[0059] The DC first port 14 is connected between the first end of the upper arm circuit and the second end of the lower arm circuit through a third switch (S3) and a bidirectional DC / DC circuit to output power to or input power from an external first DC device;

[0060] The DC second port 15 is connected between the first end of the upper bridge arm circuit and the second end of the lower bridge arm circuit through the fourth switch (S4) to output power to or input power from an external second DC device.

[0061] Both the upper bridge arm circuit and the lower bridge arm circuit include a plurality of cascaded bridge arm sub-modules (SM) and bridge arm inductors (Lap, Lbp, Lcp, Lan, Lbn, Lcn). Each bridge arm sub-module includes: a capacitor, a battery pack, and a plurality of switching tubes. The plurality of switching tubes and the capacitor form a full-bridge circuit, and the capacitor is connected in parallel with the battery pack.

[0062] The auxiliary controller is connected to the bridge arm sub-module.

[0063] The main controller is respectively connected to the AC first port, the AC second port, the DC first port, the DC second port, and the auxiliary controller.

[0064] In the embodiment of the present application, the auxiliary controller is used to detect the state information of each battery in the battery pack, and based on the detected state information of each battery, achieve the remaining power balance control of each battery in the battery pack by means of a bypass resistor, and obtain the power information of the battery pack according to the state information of each battery, and output it to the main controller.

[0065] The main controller is used to detect the power information of the AC first port, the AC second port, the DC first port, and the DC second port, and respectively determine the balance power information of each bridge arm sub-module based on the detected power information and the power information uploaded by the auxiliary controller, and output it to the corresponding auxiliary controller, so that the auxiliary controller generates a control signal for controlling the on-off duration of the switching tubes in the bridge arm sub-module according to the obtained power information of the battery pack and the balance power information, so as to balance the remaining power of each bridge arm sub-module.

[0066] In the embodiment of the present application, each phase circuit forms a phase-level converter.

[0067] In the embodiments of the present application, by setting a master controller, the power information of each port can be detected. According to the detected power information and the power information of the battery pack uploaded by the auxiliary controller, the balanced power information of each leg sub-module is determined respectively, and the auxiliary controller is enabled to generate a control signal for balancing the remaining power of the leg sub-module according to the power information of the battery pack and the balanced power information, so as to control the on / off of the switching tubes in the corresponding leg sub-module by using the control signal and control the remaining power of the leg sub-module. At the same time, the auxiliary controller is used to realize the remaining power balance control of each battery in the battery pack by means of a bypass resistor according to the detected state information of each battery. In this way, the power balance between the leg sub-modules and the batteries within the leg sub-module can be achieved without modifying the circuit structure of the powertrain system, making the output of the powertrain system stable, improving the stability of the operation of the powertrain system, and effectively increasing the service life and usage efficiency of the power components in the powertrain system. Further, by configuring different AC ports and DC ports for the powertrain system, both the configured AC ports and DC ports can achieve two-way matching of different powers, so as to meet the operation requirements of different devices. By flexibly configuring the functions and types of each port, the powertrain system can be used in different types of power drive and energy management scenarios. Moreover, multiple switching tubes and capacitors in the leg sub-module form a full-bridge circuit, and by adjusting the on / off duration of the full-bridge circuit, the output power magnitude of the leg sub-module can be adjusted to form diversified power outputs, which can meet the operation of devices with different power requirements.

[0068] In the embodiments of the present application, as an optional embodiment, the number of phase circuits is three, and each phase circuit corresponds to a phase-level converter, including: a first phase-level converter, a second phase-level converter, and a third phase-level converter.

[0069] In the embodiments of the present application, as an optional embodiment, the upper-arm circuit includes a plurality of upper-arm sub-modules and an upper-arm inductor connected in series in sequence; the lower-arm circuit includes a plurality of lower-arm sub-modules and a lower-arm inductor connected in series in sequence;

[0070] The first AC port is connected between the upper-arm inductor and the lower-arm inductor through a first switch;

[0071] The first end of the second AC port is connected to the inverter inductor, and the second end is connected between the upper-arm inductor and the lower-arm inductor through a second switch.

[0072] In the embodiments of the present application, as an optional embodiment, the upper-arm sub-module and the lower-arm sub-module have the same structure, and the first phase-level converter, the second phase-level converter, and the third phase-level converter also have the same structure.

[0073] Taking the first-phase level converter as an example, it includes a first upper-bridge-arm circuit and a first lower-bridge-arm circuit connected to the first upper-bridge-arm circuit. The first upper-bridge-arm circuit may include 16 upper-bridge-arm sub-modules and an upper-bridge-arm inductor (Lap), and the first lower-bridge-arm circuit includes 16 lower-bridge-arm sub-modules and a lower-bridge-arm inductor (Lan). Among them, the 16 upper-bridge-arm sub-modules are marked as SM1 - SM16, and the 16 lower-bridge-arm sub-modules are marked as SM17 - SM32. Among them, SM1 to SM16 are cascaded in sequence. SM1 (the positive output terminal, that is, the first end of the upper-bridge-arm circuit: Udc+) is connected to the positive pole of the first DC port. SM16 is also connected to one end of the upper-bridge-arm inductor. The other end of the upper-bridge-arm inductor is connected to one end of the lower-bridge-arm inductor. The other end of the lower-bridge-arm inductor is connected to SM17. SM17 - SM32 are cascaded in sequence. SM32 (the negative output terminal, that is, the second end of the lower-bridge-arm circuit: Udc-) is also connected to the negative pole of the first DC port.

[0074] Figure 2 It is a schematic diagram of the structure of the bridge-arm sub-module provided by the embodiment of the present application. As Figure 2 shown, the bridge-arm sub-module includes: a first switch tube (T1), a second switch tube (T2), a third switch tube (T3), a fourth switch tube (T4), a first capacitor (C), a first diode (D1), a second diode (D2), a third diode (D3), a fourth diode (D4), and a battery pack (B). Among them,

[0075] The collector of the first switch tube is respectively connected to the collector of the second switch tube, the negative pole of the first diode, one end of the first capacitor, and the positive pole of the battery pack;

[0076] The emitter of the first switch tube is respectively connected to the collector of the third switch tube and the positive pole of the first diode;

[0077] The emitter of the third switch tube is respectively connected to the emitter of the fourth switch tube, the positive pole of the third diode, the other end of the first capacitor, and the negative pole of the battery pack;

[0078] The negative pole of the third diode is connected to the collector of the third switch tube;

[0079] The emitter of the second switch tube is respectively connected to the collector of the fourth switch tube and the positive pole of the second diode;

[0080] The negative pole of the second diode is connected to the collector of the second switch tube;

[0081] The negative pole of the fourth diode is connected to the collector of the fourth switch tube, and the positive pole is connected to the emitter of the fourth switch tube;

[0082] The bases of the first switch tube, the second switch tube, the third switch tube, and the fourth switch tube are connected to control signals;

[0083] The emitter of the first switching transistor serves as the first end of the cascaded arm sub-module, and the emitter of the second switching transistor serves as the second end of the cascaded arm sub-module and is connected to the first end of the next cascaded arm sub-module.

[0084] In the embodiment of the present application, the first switching transistor, the second switching transistor, the third switching transistor, the fourth switching transistor, and the first capacitor form an H-bridge circuit, and the battery pack is connected in parallel with the first capacitor of the H-bridge circuit to form an arm sub-module. In this way, by connecting the first capacitor in parallel at both poles of the battery pack, the voltage fluctuation on the arm sub-module (the internal resistance of the battery is generally small. If the voltage fluctuation is large, it will cause a large current on the internal resistance) can be effectively avoided, and the phenomenon of battery burning can be prevented.

[0085] In the embodiment of the present application, as an alternative embodiment, when the arm current direction points to the connection point of the first switching transistor and the third switching transistor, when the first switching transistor and the fourth switching transistor are turned on, the battery pack can be charged. Correspondingly, when the second switching transistor and the third switching transistor are turned on, the battery pack can be discharged. When the first switching transistor and the second switching transistor are turned on, or when the third switching transistor and the fourth switching transistor are turned on, the isolation of the arm sub-module can be achieved.

[0086] When the arm current direction points to the connection point of the second switching transistor and the fourth switching transistor, the second switching transistor and the third switching transistor are turned on to charge the battery pack, and the first switching transistor and the fourth switching transistor are turned on to discharge the battery pack.

[0087] In the embodiment of the present application, when the switching transistor is in a de-energized state, as an alternative embodiment, after an abnormality or a fault occurs in the arm sub-module, in order to effectively isolate the arm sub-module, the arm sub-module may further include:

[0088] A bipolar diode (not shown in the figure), including a fifth diode and a sixth diode, the fifth diode and the sixth diode are connected in reverse series. Among them, the positive electrode of the fifth diode is connected to the first end of the arm sub-module, the negative electrode of the fifth diode is connected to the negative electrode of the sixth diode, and the positive electrode of the sixth diode is connected to the second end of the arm sub-module. In this way, the bipolar diode provides overvoltage protection for the arm sub-module connected in parallel therewith. When the arm sub-module is abnormal or faulty and the on / off of the switching transistor cannot be effectively controlled, the abnormal or faulty arm sub-module can be removed by turning on the bipolar diode.

[0089] In the embodiment of the present application, all the arm sub-modules in each phase-level converter are sequentially connected in series to form a sub-phase module, and the sub-phase modules of each phase-level converter are connected in parallel to form a sub-module port.

[0090] In an embodiment of the present application, as an optional embodiment, the control signal is a pulse width modulation (PWM) signal. The main controller determines the equalization power information of each arm sub-module by obtaining the power information of the first AC port, the second AC port, the first DC port, the second DC port, and the power information of the battery pack uploaded by the auxiliary controller, and outputs it to the corresponding auxiliary controller, so that the auxiliary controller generates a PWM signal with a corresponding duty cycle, which can control the on and off duration of the switching tubes in the arm sub-module, thereby controlling the voltage across the capacitor and realizing the charging or discharging of the battery pack. For example, when it is determined according to the obtained power information of the first AC port, the second AC port, the first DC port, the second DC port, and the state information of each battery uploaded by the auxiliary controller that the battery pack in the arm sub-module needs to output power, by determining the equalization power information of each arm sub-module, the auxiliary controller is enabled to control the voltage across the capacitor to be lower than the battery pack voltage, causing the battery pack to discharge. And when it is determined according to the obtained power information of the first AC port, the second AC port, the first DC port, the second DC port, and the power information of the battery pack uploaded by the auxiliary controller that the battery pack in the arm sub-module needs to be charged, by determining the equalization power information of each arm sub-module, the auxiliary controller is enabled to control the voltage across the capacitor to be higher than the battery pack voltage to charge the battery pack, thereby realizing power equalization between the arm sub-modules.

[0091] Figure 3 It is a schematic diagram of the battery pack structure provided by the embodiment of the present application. As Figure 3 shown, in the embodiment of the present application, a plurality of cascaded battery modules form a battery pack, and each battery module includes a plurality of parallel-connected batteries. The number of parallel-connected batteries and the number of series-connected battery modules can be jointly determined according to a series of factors such as space volume, heat dissipation, and economic cost. In the embodiment of the present application, the auxiliary controller can utilize battery management system (BMS) technology to determine the remaining power of the battery by detecting the state information of each battery in the battery pack, such as voltage information, current information, etc., and obtain the battery with abnormal power (remaining power) in the battery pack that is higher than the preset power threshold through methods such as ampere-hour integration method, open-circuit voltage method, Kalman filtering method, or neural network algorithm, and realize the power (remaining power) equalization of each battery in the battery pack by connecting a bypass resistor with a large resistance value in parallel at both poles of the battery with abnormal power.

[0092] In an embodiment of the present application, as an optional embodiment, the first AC port can realize the drive of the motor and the energy feedback of the motor, that is, by controlling the on and off duration of the switching tubes in the arm sub-module to control the magnitude of the arm circulating current and the AC side current, forming a voltage drop at the first AC port to generate a charging and discharging current, achieving the purpose of power exchange.

[0093] In an embodiment of the present application, as an alternative embodiment, the AC second port can be connected to an external AC charging pile or the power grid. Through this AC second port, AC charging can be performed for the powertrain system. Among them, Lac is the inductor required for the inverter to be connected to the grid. Assuming that the grid voltage on the AC side is u1 and the output voltage of the converter in the powertrain system is an adjustable u2. In this embodiment, by controlling the magnitude of u2, a voltage difference is generated between u1 and u2, causing a voltage drop across Lac, and the voltage drop generates a current. Therefore, by controlling the magnitude of u2, the magnitude and direction of the current on Lac can be controlled, thereby controlling the charging of the inner bridge arm circuit of the converter from the AC side, or the discharging of the inner bridge arm circuit of the converter to the AC side.

[0094] In an embodiment of the present application, the difference between the output voltage of the upper bridge arm sub-module and the output voltage of the lower bridge arm sub-module is the AC voltage of the AC port. In practical applications, other AC ports can also be extended and set.

[0095] In an embodiment of the present application, as an alternative embodiment, the DC first port provides power to the in-vehicle air conditioner and auxiliary equipment in the form of DC voltage and DC current, and energy feedback of the auxiliary equipment can also be realized. Among them, the bidirectional DC / DC circuit performs DC voltage conversion to meet the power supply requirements of the auxiliary equipment.

[0096] In an embodiment of the present application, as another alternative embodiment, the bidirectional DC / DC circuit of the DC first port can also charge the powertrain system.

[0097] In an embodiment of the present application, as an alternative embodiment, the DC second port is connected to a DC charging pile. Through this DC second port, DC charging can be performed for the powertrain system.

[0098] In an embodiment of the present application, the sum of the output voltage of the upper bridge arm sub-module and the output voltage of the lower bridge arm sub-module is the DC voltage of the DC port. By setting different DC ports, the operating requirements of different devices can be met. For example, different DC ports can be set to correspond to different power consumptions. For example, the bidirectional DC / DC circuit on the first DC port may step down the 600V output by the bridge arm circuit to 12V, and the output current is not large either; the second DC port can step down the 750V output by the bridge arm circuit to 600V, and the current for supercharging may be 300A.

[0099] In an embodiment of the present application, as another alternative embodiment, the direct current output by the powertrain system or the direct current input to the powertrain system can also be filtered to reduce the ripple disturbance of the direct current. Therefore, the powertrain system further includes:

[0100] A second capacitor 16 and a third capacitor 17, the second capacitor 16 and the third capacitor 17 are connected in series. One end of the second capacitor 16 is connected to the first end of the upper bridge arm circuit, the other end is connected to one end of the third capacitor 17, the other end of the third capacitor 17 is connected to the second end of the lower bridge arm circuit, and the other end of the second capacitor 16 and one end of the third capacitor 17 are grounded.

[0101] In an embodiment of the present application, as another alternative embodiment, external photovoltaic power generation can also be connected to charge the battery pack. Therefore, the powertrain system further includes:

[0102] A DC third port (not shown in the figure), including: a fifth switch (S5), a unidirectional DC / DC circuit, a reverse diode, and a photovoltaic (PV) array, where

[0103] The first end of the fifth switch is connected to the first end of the upper bridge arm circuit, the second end is connected to the second end of the lower bridge arm circuit, the third end is connected to the first output end of the unidirectional DC / DC circuit, and the fourth end is connected to the second output end of the unidirectional DC / DC circuit;

[0104] The first input end of the unidirectional DC / DC circuit is connected to the negative electrode of the reverse diode;

[0105] The positive electrode of the reverse diode is connected to the first output end of the photovoltaic array;

[0106] The second output end of the photovoltaic array is connected to the second input end of the unidirectional DC / DC circuit.

[0107] In an embodiment of the present application, through the DC third port, the photovoltaic power generation of the photovoltaic array can be utilized to perform photovoltaic charging on the powertrain system.

[0108] Figure 4 It is a schematic connection structure diagram of the main controller and the auxiliary controller provided by the embodiment of the present application. As Figure 4 shown, in an embodiment of the present application, the main controller communicates with each port (including the DC port and the AC port) and each auxiliary controller, detects the power information of each port and receives the power information of the battery pack reported by each auxiliary controller. Each auxiliary controller communicates with a bridge arm sub-module, detects the state information of each battery in the bridge arm sub-module, and performs power balancing control on the batteries in the bridge arm sub-module according to the detected state information of each battery; according to the detected state information of each battery, calculates the power information of the bridge arm sub-module (battery pack), and reports the calculated power information of the bridge arm sub-module to the main controller.

[0109] In an embodiment of the present application, the master controller can determine the operating state of the powertrain system according to the type of device connected to the port (for example, a certain type of port can only be connected to a certain type of device). For example, when it is detected that an electric vehicle charging pile is inserted into a certain port, it is determined that the powertrain system is in a charging state, and power output to the motor is not allowed, and then an enable signal is output to turn off the switch of the corresponding port of the motor.

[0110] Figure 5 It is a schematic structural diagram of the auxiliary controller provided by the embodiment of the present application. As Figure 5 shown, in an embodiment of the present application, an auxiliary controller is correspondingly arranged for each arm sub-module. The auxiliary controller includes: a communication unit, a processor, a driving unit, a sampling unit, and an equalizing unit, where

[0111] the communication unit is connected to the processor, and the processor is also respectively connected to the driving unit, the sampling unit, and the equalizing unit. The sampling unit and the equalizing unit are also respectively connected to each battery in the battery pack.

[0112] The sampling unit is configured to sample the state information of each battery in the battery pack and output the sampled state information of the battery to the processor;

[0113] The processor receives the state information of each battery output by the sampling unit, obtains the battery with abnormal power higher than the preset power threshold in the battery pack, and notifies the equalizing unit to realize the power balance of each battery in the battery pack by connecting a bypass resistor with a large resistance in parallel at both poles of the battery with abnormal power;

[0114] calculate the power information of the arm sub-module according to the detected state information of each battery, and report the calculated power information of the arm sub-module to the master controller through the communication unit;

[0115] receive the equalizing power information sent by the master controller through the communication unit and output it to the driving unit;

[0116] The driving unit receives the equalizing power information, generates a control signal for equalizing the remaining power of the arm sub-module according to the power information of the arm sub-module and the equalizing power information, and uses the control signal to control the on-off duration of the switching tube in the arm sub-module, so as to equalize the remaining power of each arm sub-module.

[0117] In an embodiment of the present application, the sampling unit collects the battery module voltage and current in the battery pack corresponding to the arm sub-module, and the processor compares and analyzes to determine whether the energy is balanced between the battery modules. If there is an imbalance phenomenon, the equalizing unit is enabled to discharge the unbalanced battery module through a parallel resistor or bypass it through a bypass switch, so as to realize the passive energy balance between each battery module in the battery pack.

[0118] In the embodiment of the present application, the master controller determines the balanced power of each arm sub-module port through the control of the energy sum of the upper and lower arm circuits, the control of the energy difference of the upper and lower arm circuits, the suppression of the circulating current in the arm circuit, the capacitor voltage sorting algorithm of the arm sub-module, the constant DC bus voltage control, the constant AC power control, the nearest level approximation method, or the carrier phase-shifted modulation, etc., so as to balance the remaining power of each arm sub-module port.

[0119] Combined Figure 4 with Figure 5 , in the embodiment of the present application, it is assumed that the AC first port outputs a rated power X, which is used to drive the motor, the AC second port does not work, the DC first port outputs 12V (this voltage is used to supply power to loads such as the air conditioner, heater, defroster, cigarette lighter, and mobile phone charger in the vehicle, and the loads are not started and do not consume power), the DC second port does not work, and the DC third port inputs a power Y. All devices in the powertrain system are working properly.

[0120] The master controller collects internal and external information of the powertrain system, such as the working status of each port, the type of access device at the port, the port voltage and current (power), etc. According to the collected information, it judges whether the powertrain system is in a fault state. If no fault occurs, it proceeds to the next step. If it is in a fault state, it judges whether the powertrain system can continue to operate after removing the faulty port. If so, it proceeds to the next step, otherwise it shuts down.

[0121] Based on the rated power X required to be output by the AC first port and the input power Y of the DC third port, calculate the total output power required to be output by the AC first port as: X - Y, and based on the power information of each arm sub-module, use the energy sum control method of the upper and lower arm circuits to perform power balance control and allocate balanced power to each arm sub-module. Among them, the balanced power allocated to some arm sub-modules may be negative (for example, the remaining power of this arm sub-module is much lower than the statistical remaining power average), indicating that the battery pack of this arm sub-module needs to be charged.

[0122] Send an output power command value containing the corresponding balanced power information to each auxiliary controller, disconnect the switch of the AC second port by sending an enable signal, and, send an enable signal to disconnect the DC second port.

[0123] The auxiliary controller calculates the average output power of the arm sub-module, and after superimposing the output power command value, obtains the PWM signal of the switching tube in the corresponding arm sub-module.

[0124] Use the obtained PWM signal to drive the switching tube of the arm sub-module.

[0125] In the embodiments of the present application, the auxiliary processor calculates the switching states of the H-bridge circuits in the corresponding arm sub-modules based on information such as the battery information, the capacitor voltages of the arm sub-modules, the currents of the arm sub-modules, and the power commands issued by the master controller collected by the sampling unit, and sends switching drive signals (PWM signals) through the drive unit. On the premise of ensuring that the total output power of the arm sub-module ports is equal to the command value issued by the master controller, the energy differences between the battery packs are transferred by using the capacitors in the arm sub-modules, so as to achieve active energy balancing between the battery packs of each arm sub-module.

[0126] In the embodiments of the present application, as an alternative embodiment, the master controller and the auxiliary controller may be integrated circuit chips with signal processing capabilities. The integrated circuit chips may be general-purpose processors, including central processing units (CPUs), network processors (NPs), etc.; they may also be digital signal processors (DSPs), application specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), other programmable logic devices, discrete gate, transistor logic devices, discrete hardware components, etc.

[0127] In the embodiments of the present application, as an alternative embodiment, the switching tubes include, but are not limited to: triodes, field effect transistors, transistors, and other electronic devices or integrated circuits that can realize the switching of the on / off state of the circuit.

[0128] In the embodiments of the present application, the power-train systems may also be connected to each other to achieve mutual charging between the power-train systems. For example, if the number of power-train systems is 2, the two power-train systems are connected through the second DC port to achieve mutual charging, and the two power-train systems respectively realize the charging and discharging of the batteries in the corresponding arm sub-modules through the switching tubes in their respective arm sub-modules.

[0129] In the embodiments provided in the present application, it should be understood that the disclosed devices and methods may be implemented in other ways. The device embodiments described above are merely illustrative. For example, the division of the units is only a logical function division, and there may be other division methods in actual implementation. For another example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Another point is that the displayed or discussed couplings or direct couplings or communication connections to each other may be through some communication interfaces, and the indirect couplings or communication connections of the devices or units may be in electrical, mechanical or other forms.

[0130] The unit described as a separation component may or may not be physically separated. The component shown as a unit may or may not be a physical unit, that is, it may be located in one place or may be distributed over multiple network units. Some or all of the units can be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0131] In addition, each functional unit in the embodiments provided in this application can be integrated into a processing unit, or each unit can exist physically alone, or two or more units can be integrated into one unit.

[0132] If the described function is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of this application, in essence, or the part that contributes to the prior art or a part of this technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions for causing a computer device (which can be a personal computer, a server, or a network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of this application. The aforementioned storage medium includes: various media that can store program codes such as USB flash drives, mobile hard disks, read-only memories (ROM, Read-Only Memory), random access memories (RAM, Random Access Memory), magnetic disks, or optical discs.

[0133] It should be noted that: similar reference numerals and letters represent similar items in the following drawings. Therefore, once an item is defined in one drawing, it does not need to be further defined and explained in subsequent drawings. In addition, the terms "first", "second", "third", etc. are only used for distinguishing descriptions and cannot be understood as indicating or implying relative importance.

[0134] Finally, it should be noted that: the above-described embodiments are only specific implementation manners of this application, used to illustrate the technical solutions of this application, rather than limiting it. The protection scope of this application is not limited thereto. Although this application has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: any person skilled in the art within the technical scope disclosed in this application can still modify the technical solutions recorded in the foregoing embodiments, or can easily think of changes, or perform equivalent replacements for some of the technical features; and these modifications, changes, or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of this application. All should be covered within the protection scope of this application. Therefore, the protection scope of this application should be subject to the protection scope of the claims.

Claims

1. A powertrain system based on a modular multilevel converter, the powertrain system comprising: an AC first port, an AC second port, a plurality of parallel - connected phase circuits, a DC first port, a DC second port, an auxiliary controller, and a main controller, wherein each phase circuit includes: an upper - arm circuit and a lower - arm circuit, and the second end of the upper - arm circuit is cascaded with the first end of the lower - arm circuit; The AC first port is connected between the second end of the upper - arm circuit and the first end of the lower - arm circuit through a first switch, and outputs power to an external first AC device or inputs power from the first AC device; The AC second port is connected between the second end of the upper - arm circuit and the first end of the lower - arm circuit through an inverter inductor and a second switch, and outputs power to an external second AC device or inputs power from the second AC device; The DC first port is connected between the first end of the upper - arm circuit and the second end of the lower - arm circuit through a third switch and a bidirectional DC / DC circuit, and outputs power to an external first DC device or inputs power from the first DC device; The DC second port is connected between the first end of the upper - arm circuit and the second end of the lower - arm circuit through a fourth switch, and outputs power to an external second DC device or inputs power from the second DC device; Both the upper - arm circuit and the lower - arm circuit include a plurality of cascaded arm sub - modules and arm inductors, and each arm sub - module includes: a capacitor, a battery pack, and a plurality of switching tubes. The plurality of switching tubes and the capacitor form a full - bridge circuit, and the capacitor is connected in parallel with the battery pack; The auxiliary controller is used to detect the state information of each battery in the battery pack, and based on the detected state information of each battery, achieve the remaining charge equalization control of each battery in the battery pack by means of a bypass resistor, and obtain the power information of the battery pack according to the state information of each battery, and output it to the main controller; The main controller is used to detect the power information of the AC first port, the AC second port, the DC first port, and the DC second port, and based on the detected power information and the power information uploaded by the auxiliary controller, respectively determine the equalization power information of each arm sub - module, and output it to the corresponding auxiliary controller, so that the auxiliary controller generates a control signal for controlling the on - off duration of the switching tubes in the arm sub - module according to the obtained power information of the battery pack and the equalization power information, so as to balance the remaining power of each arm sub - module; When the control signal is a pulse - width modulation signal, the main controller outputs the equalization power information to the corresponding auxiliary controller, so that the auxiliary controller generates a PWM signal with a corresponding duty cycle, which can control the on - off duration of the switching tubes in the arm sub - module, thereby controlling the voltage across the capacitor and realizing the charging or discharging of the battery pack; The main controller calculates the total output power required to be output by the AC first port according to the rated power required to be output by the AC first port and the input power of the DC third port, and based on the power information of each arm sub - module, performs power equalization control by using the energy - sum control method of the upper and lower arm circuits, and allocates equalization power to each arm sub - module.

2. The powertrain system according to claim 1, characterized in that, The upper bridge arm circuit includes a plurality of series-connected upper bridge arm sub-modules and an upper bridge arm inductor; the lower bridge arm circuit includes a plurality of series-connected lower bridge arm sub-modules and a lower bridge arm inductor; The first AC port is connected between the upper bridge arm inductor and the lower bridge arm inductor through a first switch; The first end of the second AC port is connected to the inverter inductor, and the second end is connected between the upper bridge arm inductor and the lower bridge arm inductor through a second switch.

3. The powertrain system according to claim 1, characterized in that, The bridge arm sub-module includes: a first switch tube, a second switch tube, a third switch tube, a fourth switch tube, a first capacitor, a first diode, a second diode, a third diode, a fourth diode, and a battery pack, where The collector of the first switch tube is respectively connected to the collector of the second switch tube, the negative electrode of the first diode, one end of the first capacitor, and the positive electrode of the battery pack; The emitter of the first switch tube is respectively connected to the collector of the third switch tube and the positive electrode of the first diode; The emitter of the third switch tube is respectively connected to the emitter of the fourth switch tube, the positive electrode of the third diode, the other end of the first capacitor, and the negative electrode of the battery pack; The negative electrode of the third diode is connected to the collector of the third switch tube; The emitter of the second switch tube is respectively connected to the collector of the fourth switch tube and the positive electrode of the second diode; The negative electrode of the second diode is connected to the collector of the second switch tube; The negative electrode of the fourth diode is connected to the collector of the fourth switch tube, and the positive electrode is connected to the emitter of the fourth switch tube; The bases of the first switch tube, the second switch tube, the third switch tube, and the fourth switch tube are connected to control signals; The emitter of the first switch tube serves as the first end of the cascaded bridge arm sub-module, and the emitter of the second switch tube serves as the second end of the cascaded bridge arm sub-module and is connected to the first end of the next cascaded bridge arm sub-module.

4. The powertrain system according to claim 3, wherein, When the bridge arm current direction points to the connection point of the first switch tube and the third switch tube, the first switch tube and the fourth switch tube are turned on to charge the battery pack, the second switch tube and the third switch tube are turned on to discharge the battery pack, the first switch tube and the second switch tube are turned on, or the third switch tube and the fourth switch tube are turned on to isolate the bridge arm sub-module.

5. The powertrain system according to claim 3, characterized in that, The bridge arm sub-module further includes: Bipolar diodes, including a fifth diode and a sixth diode, which are reversely connected in series. Among them, the positive electrode of the fifth diode is connected to the first end of the bridge arm sub-module, the negative electrode of the fifth diode is connected to the negative electrode of the sixth diode, and the positive electrode of the sixth diode is connected to the second end of the bridge arm sub-module.

6. The powertrain system according to claim 3, wherein, The battery pack includes a plurality of cascaded battery modules, and each battery module includes a plurality of parallel-connected batteries.

7. The powertrain system according to any one of claims 1 to 6, characterized in that, It further includes: A second capacitor and a third capacitor, where The second capacitor and the third capacitor are connected in series. One end of the second capacitor is connected to the first end of the upper bridge arm circuit, the other end is connected to one end of the third capacitor, the other end of the third capacitor is connected to the second end of the lower bridge arm circuit, and the other end of the second capacitor and one end of the third capacitor are grounded.

8. The powertrain system according to claim 7, characterized in that, It further includes: A DC third port, including: a fifth switch, a unidirectional DC / DC circuit, a reverse diode, and a photovoltaic array, where The first end of the fifth switch is connected to the first end of the upper bridge arm circuit, the second end is connected to the second end of the lower bridge arm circuit, the third end is connected to the first output end of the unidirectional DC / DC circuit, and the fourth end is connected to the second output end of the unidirectional DC / DC circuit; The first input end of the unidirectional DC / DC circuit is connected to the negative electrode of the reverse diode; The positive electrode of the reverse diode is connected to the first output end of the photovoltaic array; The second output end of the photovoltaic array is connected to the second input end of the unidirectional DC / DC circuit.

9. The powertrain system according to any one of claims 1 to 6, characterized in that, The auxiliary controller includes: a communication unit, a processor, a driving unit, a sampling unit, and a balancing unit, where The communication unit is connected to the processor, and the processor is also respectively connected to the driving unit, the sampling unit, and the balancing unit. The sampling unit and the balancing unit are also respectively connected to each battery in the battery pack; The sampling unit is configured to sample the state information of each battery in the battery pack and output the sampled state information of the battery to the processor; The processor receives the state information of each battery output by the sampling unit, obtains the battery with abnormal power higher than the preset power threshold in the battery pack, and notifies the balancing unit to parallel a bypass resistor with a large resistance value at both poles of the battery with abnormal power, so as to achieve power balance of each battery in the battery pack; Calculate the power information of the bridge arm sub-module according to the detected state information of each battery, and report the calculated power information of the bridge arm sub-module to the main controller through the communication unit; Receive the balancing power information sent by the main controller through the communication unit and output it to the driving unit; The driving unit receives the balancing power information, generates a control signal for balancing the remaining power of the bridge arm sub-module according to the power information of the bridge arm sub-module and the balancing power information, and uses the control signal to control the on-off duration of the switching tube in the bridge arm sub-module, so as to balance the remaining power of each bridge arm sub-module.

10. The powertrain system according to any one of claims 1 to 6, characterized in that The number of the powertrain systems is 2. The two powertrain systems are connected through the second DC port to realize mutual charging. The two powertrain systems respectively realize the charging and discharging of the batteries in the corresponding bridge arm sub-module through the switching tubes in their respective bridge arm sub-modules.

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