Management methods and related components for charging lithium batteries using a three-phase AC motor

Abstract

This invention discloses a management method and related components for charging a lithium battery using a three-phase AC motor. The method is applied to a bridge circuit located between the lithium battery and the three-phase AC motor. When the three-phase AC motor is in generator mode and its speed is low, the various switches in the bridge circuit are controlled to boost and rectify the AC output from the motor, ensuring that the output DC voltage is within a preset charging voltage range and the DC current is a preset current. This application not only ensures that the output voltage of the bridge circuit is within the preset charging voltage range, allowing the three-phase AC motor to charge the lithium battery normally, but also guarantees that the output power of the three-phase AC motor varies within a preset range. It reuses the bridge circuit used when the lithium battery powers the three-phase AC motor, saving system costs.

Description

Technical Field

[0001] This invention relates to the field of motor control, and in particular to a management method and related components for a three-phase AC motor charging a lithium battery. Background Technology

[0002] An internal combustion engine is a thermoelectric motor that converts the heat energy released from burning fuel inside the machine into power. In some vehicles or small aircraft, the three-phase AC motor used for the starter-generator is typically mounted on the crankshaft of the internal combustion engine. To ensure battery power supply to the three-phase AC motor, a storage battery (such as a 48V or 28V lithium battery) is usually installed. During the starting process of the internal combustion engine, a bridge circuit is used between the battery and the three-phase AC motor. By controlling the switching transistors in the bridge circuit, the voltage output from the battery is inverted, allowing the battery to supply power to the three-phase AC motor, which then operates as a motor to drive the internal combustion engine. When the internal combustion engine speed is not less than the starting speed, the motor management system can control the ignition and start the internal combustion engine. After the internal combustion engine starts, it drives the three-phase AC motor, which operates as a generator, charging the battery pack through a charging circuit.

[0003] Patent Document 1: CN108412655A

[0004] Patent Document 2: CN111003188A

[0005] In the existing technology, the charging circuit and the starting circuit (bridge circuit) for charging the battery are separate. That is, the starting circuit only works when the internal combustion engine is starting; after starting, the starting circuit should be disconnected from the entire control system (controlled by a relay) to avoid the starting circuit and the generator circuit interfering with each other when the internal combustion engine reaches high speed, which could damage the entire integrated starter-generator control system.

[0006] In addition, the three-phase AC motor used in the aforementioned hybrid vehicles or small aircraft for integrated starter-generators needs to be rectified and DC-DC (Direct Current-Direct Current) converted to charge the battery. This not only increases the system cost, but also reduces the system's reliability and increases its weight due to the increase in components.

[0007] Furthermore, in the aforementioned hybrid vehicles or small aircraft using integrated starter-generator three-phase AC motors, the battery needs to be charged via a DC-DC converter when the motor (motor) is running at low speeds. This is because the motor speed is low, and the back electromotive force is also low. Conventional rectification methods do not provide a boost effect, and the rectified DC voltage is insufficient to reach the battery's charging voltage, necessitating the addition of a boost-type DC-DC converter. Summary of the Invention

[0008] The purpose of this invention is to provide a management method and related components for charging a lithium battery with a three-phase AC motor. This method not only ensures that the voltage output by the bridge circuit is within a preset charging voltage range so that the three-phase AC motor can charge the lithium battery normally, but also ensures that the output power of the three-phase AC motor varies within a preset range. It reuses the bridge circuit used when the lithium battery supplies power to the three-phase AC motor, thus saving system costs.

[0009] To address the aforementioned technical problems, this invention provides a management method for a three-phase AC motor charging a lithium battery, applied to a bridge circuit located between the lithium battery and the three-phase AC motor; the method includes:

[0010] Determine whether the three-phase AC motor is currently in generator mode;

[0011] If the generator is in the generator state, determine whether the speed of the three-phase AC motor is less than the preset speed;

[0012] If the speed is less than the preset speed, then each switch in the bridge circuit is controlled so that the bridge circuit boosts and rectifies the AC power output by the three-phase AC motor, and the voltage of the output DC power is within the preset charging voltage range of the lithium battery, and the current of the DC power is the preset current.

[0013] The product of the DC current and voltage output by the bridge circuit is not greater than the rated power of the three-phase AC motor.

[0014] Preferably, the bridge circuit includes a first bridge arm connected to the A-phase coil of the three-phase AC motor, a second bridge arm connected to the B-phase coil of the three-phase AC motor, and a third bridge arm connected to the C-phase coil of the three-phase AC motor.

[0015] The switching transistors in the bridge circuit are controlled to boost and rectify the AC power output from the three-phase AC motor. The output DC voltage is within the preset charging voltage range, and the DC current is a preset current, including:

[0016] Each switch in each arm of the bridge circuit is controlled sequentially so that the bridge circuit boosts and rectifies the AC power output from the three-phase AC motor, and the output DC voltage is within the preset charging voltage range, and the DC current is the preset current.

[0017] Preferably, the first bridge arm includes a first switch and a fourth switch, the second bridge arm includes a second switch and a fifth switch, and the third bridge arm includes a third switch and a sixth switch; the first end of the first switch is connected to the positive terminal of the lithium battery, the second end of the first switch is connected to the first end of the fourth switch, and the second end of the fourth switch is connected to the negative terminal of the lithium battery; the first end of the second switch is connected to the positive terminal of the lithium battery, the second end of the second switch is connected to the first end of the fifth switch, and the second end of the fifth switch is connected to the negative terminal of the lithium battery; the first end of the third switch is connected to the positive terminal of the lithium battery, the second end of the third switch is connected to the first end of the sixth switch, and the second end of the sixth switch is connected to the negative terminal of the lithium battery; the second ends of the first and fourth switches are connected to the A-phase winding of the three-phase AC motor; the second ends of the second and fifth switches are connected to the B-phase winding of the three-phase AC motor; the second ends of the third and sixth switches are connected to the C-phase winding of the three-phase AC motor; and the third ends of the first to sixth switches are their respective control terminals.

[0018] The switching transistors in the bridge circuit are controlled to boost and rectify the AC power output from the three-phase AC motor. The output DC voltage is within the preset charging voltage range, and the DC current is a preset current, including:

[0019] When the three-phase AC motor is in generator mode and the line voltage of phase CA of the three-phase AC motor is greater than zero, the third switch is controlled to be normally closed and the sixth switch is controlled to be normally open; when the line voltage of phase AB of the three-phase AC motor is greater than zero, the first switch is controlled to be normally closed and the fourth switch is controlled to be normally open; when the line voltage of phase BC of the three-phase AC motor is greater than zero, the second switch is controlled to be normally closed and the fifth switch is controlled to be normally open.

[0020] A PWM signal is output to the control terminal of the switching transistor when it is not in a normally closed or normally open state. The duty cycle of the PWM signal is adjusted so that the voltage of the DC power output by the bridge circuit is within the preset charging voltage range, the DC power current is a preset current, and the high and low levels of the PWM signals of the first and fourth switching transistors are opposite, the high and low levels of the PWM signals of the second and fifth switching transistors are opposite, and the high and low levels of the PWM signals of the third and sixth switching transistors are opposite.

[0021] Preferably, it further includes:

[0022] Receive the first level signal corresponding to the line voltage of the CA phase of the three-phase AC motor sent by the first Hall sensor, so as to detect the line voltage of the CA phase;

[0023] The second level signal corresponding to the line voltage of phases AB of the three-phase AC motor is received from the second Hall sensor to detect the line voltage of phases AB.

[0024] The third level signal corresponding to the line voltage of phase BC of the three-phase AC motor is received from the third Hall sensor to detect the line voltage of phase BC.

[0025] To address the aforementioned technical problems, this invention provides a management system for a three-phase AC motor charging a lithium battery, applied to a bridge circuit located between the lithium battery and the three-phase AC motor; the system includes:

[0026] The first judgment unit is used to determine whether the three-phase AC motor is currently in generator mode;

[0027] The second judgment unit is used to determine whether the speed of the three-phase AC motor is less than a preset speed when the three-phase AC motor is in the generator state.

[0028] The control unit is used to control each switch in the bridge circuit when the speed of the three-phase AC motor is less than the preset speed, so that the bridge circuit can boost and rectify the AC power output by the three-phase AC motor, and the voltage of the output DC power is within the preset charging voltage range, and the current of the DC power is the preset current.

[0029] The product of the DC current and voltage output by the bridge circuit is not greater than the rated power of the three-phase AC motor.

[0030] To solve the above-mentioned technical problems, the present invention provides a management device for a three-phase AC motor charging a lithium battery, comprising:

[0031] Memory, used to store computer programs;

[0032] A processor is configured to execute the computer program to implement the steps of the management method described above for charging a lithium battery using a three-phase AC motor.

[0033] Preferably, it further includes:

[0034] A bridge circuit is installed between the lithium battery and the three-phase AC motor;

[0035] The bridge circuit includes a first to a sixth switching transistor. The first terminal of the first switching transistor is connected to the positive terminal of the lithium battery, and its second terminal is connected to the first terminal of a fourth switching transistor. The second terminal of the fourth switching transistor is connected to the negative terminal of the lithium battery. The first terminal of the second switching transistor is connected to the positive terminal of the lithium battery, and its second terminal is connected to the first terminal of a fifth switching transistor. The second terminal of the fifth switching transistor is connected to the negative terminal of the lithium battery. The first terminal of the third switching transistor is connected to the positive terminal of the lithium battery, and its second terminal is connected to the first terminal of the sixth switching transistor. The second terminal of the sixth switching transistor is connected to the negative terminal of the lithium battery. The second terminals of the first and fourth switching transistors are connected to the A-phase winding of a three-phase AC motor. The second terminals of the second and fifth switching transistors are connected to the B-phase winding of the three-phase AC motor. The second terminals of the third and sixth switching transistors are connected to the C-phase winding of the three-phase AC motor.

[0036] Preferably, it further includes a first Hall sensor, a second Hall sensor, and a third Hall sensor disposed between the three-phase AC motor and the processor;

[0037] The first Hall sensor is used to detect the line voltage of the CA phase of the three-phase AC motor, and outputs a low level when the line voltage of the CA phase of the three-phase AC motor crosses zero from negative to positive until the line voltage of the CA phase crosses zero from positive to negative, and outputs a high level when the line voltage of the CA phase of the three-phase AC motor crosses zero from positive to negative until the line voltage of the CA phase crosses zero from negative to positive.

[0038] The second Hall sensor is used to detect the line voltage of phases AB of the three-phase AC motor, and outputs a low level when the line voltage of phases AB of the three-phase AC motor crosses zero from negative to positive until the line voltage of phases AB of the three-phase AC motor crosses zero from positive to negative, and outputs a high level when the line voltage of phases AB of the three-phase AC motor crosses zero from positive to negative until the line voltage of phases AB of the three-phase AC motor crosses zero from negative to positive.

[0039] The third Hall sensor is used to detect the line voltage of phases BC of the three-phase AC motor, and outputs a low level when the line voltage of phases BC of the three-phase AC motor crosses zero from negative to positive until the line voltage of phases BC of the three-phase AC motor crosses zero from positive to negative, and outputs a high level when the line voltage of phases BC of the three-phase AC motor crosses zero from positive to negative until the line voltage of phases BC of the three-phase AC motor crosses zero from negative to positive.

[0040] To address the aforementioned technical problems, the present invention provides a computer-readable storage medium storing a computer program, which, when executed by a processor, implements the steps of the management method for charging a lithium battery using a three-phase AC motor as described above.

[0041] This application provides a management method and related components for charging a lithium battery using a three-phase AC motor. The method is applied to a bridge circuit located between the lithium battery and the three-phase AC motor. When the three-phase AC motor is in generator mode and its speed is low, the various switches in the bridge circuit are controlled to boost and rectify the AC output from the three-phase AC motor. The output DC voltage is within a preset charging voltage range suitable for the lithium battery's charging voltage, and the DC current is a preset current. This application not only ensures that the bridge circuit output voltage is within the preset charging voltage range, allowing the three-phase AC motor to charge the lithium battery normally, but also guarantees that the output power of the three-phase AC motor varies within a preset range. It reuses the bridge circuit used when the lithium battery powers the three-phase AC motor, saving system costs. Attached Figure Description

[0042] To more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings used in the prior art and embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0043] Figure 1 A flowchart illustrating a management method for charging a lithium battery using a three-phase AC motor, provided by the present invention.

[0044] Figure 2 A schematic diagram of a bridge circuit provided by the present invention;

[0045] Figure 3 A schematic diagram of a complementary PWM signal provided by the present invention;

[0046] Figure 4 A schematic diagram of a bridge circuit in the control process provided by the present invention;

[0047] Figure 5 A schematic diagram of a bridge circuit in another control process provided by the present invention;

[0048] Figure 6 A schematic diagram of the level signal output by a Hall sensor provided by the present invention;

[0049] Figure 7A schematic diagram of a management system for charging a lithium battery using a three-phase AC motor, provided by the present invention.

[0050] Figure 8 A schematic diagram of a management device for charging a lithium battery using a three-phase AC motor, provided by the present invention.

[0051] Figure 9 A schematic diagram of the specific structure of a management device for charging a lithium battery using a three-phase AC motor provided by the present invention;

[0052] Figure 10 A schematic diagram illustrating the level signal output by a Hall sensor provided by the present invention;

[0053] Figure 11 This is a schematic diagram of a phase current and phase voltage modulation waveform provided by the present invention. Detailed Implementation

[0054] The core of this invention is to provide a management method and related components for charging a lithium battery with a three-phase AC motor. This method not only ensures that the voltage output by the bridge circuit is within a preset charging voltage range so that the three-phase AC motor can charge the lithium battery normally, but also ensures that the output power of the three-phase AC motor varies within a preset range. It reuses the bridge circuit used when the lithium battery supplies power to the three-phase AC motor, thus saving system costs.

[0055] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0056] The following example uses a 48V lithium battery to illustrate this embodiment.

[0057] Please refer to Figure 1 , Figure 1 This invention provides a flowchart illustrating a management method for charging a lithium battery using a three-phase AC motor. The method is applied to a bridge circuit located between the lithium battery and the three-phase AC motor; the method includes:

[0058] S11: Determine whether the three-phase AC motor is currently in generator mode;

[0059] The applicant considered that after a three-phase AC motor starts, it may be in generator mode or motor mode, and the lithium battery will only be charged when it is in generator mode. Therefore, in this application, it is first determined whether the three-phase AC motor is in generator mode. Only when it is in generator mode will the bridge circuit be controlled to charge the lithium battery.

[0060] It should be noted that, to ensure the starting characteristics of the three-phase AC motor, the back electromotive force (EMF) of the motor at low speeds must be lower than the voltage of the lithium battery. Therefore, during the low-speed phase after the internal combustion engine has started, the processor needs to control the boost voltage of the motor's back EMF to ensure that the output DC power is suitable for the charging voltage of the 48V lithium battery. During the starting process of the internal combustion engine, the 48V lithium battery provides power to the three-phase AC motor through a three-phase bridge circuit, enabling the three-phase AC motor to rotate to a certain speed and drive the internal combustion engine to start.

[0061] S12: If the three-phase AC motor is currently in generator mode, determine whether the speed of the three-phase AC motor is less than the preset speed;

[0062] In addition, when the three-phase AC motor is in generator mode and the speed is less than the preset speed, the motor's back electromotive force peak value is less than the lithium battery voltage, so it cannot charge the lithium battery. It is necessary to obtain a voltage suitable for charging the lithium battery through boost control rectification.

[0063] S13: If the speed of the three-phase AC motor is less than the preset speed, then control each switch in the bridge circuit so that the bridge circuit boosts and rectifies the AC power output by the three-phase AC motor, and the voltage of the output DC power is within the preset charging voltage range of the lithium battery, and the current of the DC power is the preset current.

[0064] The product of the DC current and voltage output by the bridge circuit shall not exceed the rated power of the three-phase AC motor.

[0065] If the speed of the three-phase AC motor is less than the preset speed, in order for the three-phase AC motor to charge the lithium battery normally, this application requires that when controlling each switch in the bridge circuit, the voltage of the DC output of the bridge circuit must be greater than the voltage of the lithium battery.

[0066] To ensure that the output power of a three-phase AC motor remains within a limited range at low speeds, a constant-current charging method with variable voltage is suitable for charging lithium batteries. This is because when the motor is at low speed and the battery's state of charge is uncertain, the constant-voltage variable-current charging method causes significant variations in the motor's output power, which is detrimental to the stability of the engine, which shares a crankshaft with the motor. Especially when the battery's state of charge is low, the constant-voltage high-current charging method results in a large output power from the motor, leading to a heavy load on the motor and potentially causing the engine to stall due to insufficient power.

[0067] To address the aforementioned technical issues, this application, when controlling the bridge circuit, ensures that while the bridge circuit's output voltage remains within a preset charging voltage range, it also guarantees that the bridge circuit's output current is a preset current. Specifically, the product of the bridge circuit's output current and output voltage, i.e., the product of the DC current and voltage, is within a certain range to prevent the three-phase AC motor from having excessive output power, which could lead to excessive negative torque and engine stalling at low speeds in the internal combustion engine.

[0068] When the lithium battery voltage is 48V, the DC voltage output by the bridge circuit must be greater than 48V and not exceed 57V. That is, the preset charging voltage range can be, but is not limited to, between 48V and 57V. The output current depends on the power of the motor and the charging characteristics of the lithium battery.

[0069] In summary, this application not only ensures that the voltage output by the bridge circuit is within the preset charging voltage range so that the three-phase AC motor can charge the lithium battery normally, but also ensures that the output power of the three-phase AC motor varies within the preset range. It reuses the bridge circuit used when the lithium battery supplies power to the three-phase AC motor, thus saving system costs.

[0070] Based on the above embodiments:

[0071] As a preferred embodiment, the bridge circuit includes a first bridge arm connected to the A-phase coil of the three-phase AC motor, a second bridge arm connected to the B-phase coil of the three-phase AC motor, and a third bridge arm connected to the C-phase coil of the three-phase AC motor.

[0072] The individual switches in the bridge circuit are controlled to boost and rectify the AC output from the three-phase AC motor, ensuring the output DC voltage is within a preset charging voltage range and the DC current is a preset current, including:

[0073] Each switch in each arm of the bridge circuit is controlled sequentially so that the bridge circuit can boost and rectify the AC power output from the three-phase AC motor, and the output DC voltage is within the preset charging voltage range, and the DC current is the preset current.

[0074] The bridge circuit in this embodiment also includes three arms, which are respectively connected to the three-phase coils of the three-phase AC motor to rectify the AC power output from the three-phase coils.

[0075] In a preferred embodiment, the first bridge arm includes a first switch G1 and a fourth switch G4, the second bridge arm includes a second switch G2 and a fifth switch G5, and the third bridge arm includes a third switch G3 and a sixth switch G6; the first terminal of the first switch G1 is connected to the positive terminal of the lithium battery, the second terminal is connected to the first terminal of the fourth switch G4, and the second terminal of the fourth switch G4 is connected to the negative terminal of the lithium battery; the first terminal of the second switch G2 is connected to the positive terminal of the lithium battery, the second terminal is connected to the first terminal of the fifth switch G5, and the second terminal of the fifth switch G5 is connected to the negative terminal of the lithium battery; the third switch G3... The first terminal of switch G3 is connected to the positive terminal of the lithium battery, and the second terminal is connected to the first terminal of the sixth switch G6. The second terminal of the sixth switch G6 is connected to the negative terminal of the lithium battery. The second terminal of the first switch G1 and the first terminal of the fourth switch G4 are connected to the A-phase winding of the three-phase AC motor. The second terminal of the second switch G2 and the first terminal of the fifth switch G5 are connected to the B-phase winding of the three-phase AC motor. The second terminal of the third switch G3 and the first terminal of the sixth switch G6 are connected to the C-phase winding of the three-phase AC motor. The third terminals of the first to the sixth switches are their respective control terminals.

[0076] The individual switches in the bridge circuit are controlled to boost and rectify the AC output from the three-phase AC motor, ensuring the output DC voltage is within a preset charging voltage range and the DC current is a preset current, including:

[0077] When the three-phase AC motor is in generator mode and the line voltage of phase CA of the three-phase AC motor is greater than zero, the third switch G3 is normally closed and the sixth switch G6 is normally open; when the line voltage of phase AB of the three-phase AC motor is greater than zero, the first switch G1 is normally closed and the fourth switch G4 is normally open; when the line voltage of phase BC of the three-phase AC motor is greater than zero, the second switch G2 is normally closed and the fifth switch G5 is normally open.

[0078] The PWM signal is output to the control terminal of the switching transistor when it is not in a normally closed or normally open state. The duty cycle of the PWM signal is adjusted so that the DC voltage output by the bridge circuit is within the preset charging voltage range, the DC current is the preset current, and the high and low levels of the PWM signals of the first switching transistor G1 and the fourth switching transistor G4 are opposite, the high and low levels of the PWM signals of the second switching transistor G2 and the fifth switching transistor G5 are opposite, and the high and low levels of the PWM signals of the third switching transistor G3 and the sixth switching transistor G6 are opposite.

[0079] Please refer to Figure 2 , Figure 2 The present invention provides a schematic diagram of a bridge circuit. As can be seen, the bridge circuit is composed of multiple switching transistors, and each bridge arm is composed of two switching transistors.

[0080] To solve the above-mentioned technical problems, each switch in this application may be, but is not limited to, NMOS (N-Metal-Oxide-Semiconductor), and a bridge circuit is formed by six groups of switch transistors. Each group of switch transistors may be one or more NMOS transistors connected in parallel. The third terminals of the first to sixth switch transistors are their respective control terminals. The control terminals of each switch transistor receive PWM switching signals, which can make the first and second terminals of the corresponding switch transistors conduct, and the on-resistance is very small (usually a few milliohms).

[0081] The processor controls the on / off state of each switching transistor and the freewheeling current of the parasitic diodes in each switching transistor by detecting the polarity of the back electromotive force of the three-phase AC motor. This enables the 48V DC power from the lithium battery to flow to the three-phase AC motor through a bridge circuit, causing the three-phase AC motor to rotate and generate electromagnetic torque, which drives the internal combustion engine to rotate.

[0082] Once the three-phase AC motor drives the internal combustion engine to a certain speed, the EMS (Engine Management System) controls the engine's rotation through fuel injection and ignition. The three-phase AC motor, connected to the engine crankshaft, is driven to rotate, generating alternating current with a 120-degree electrical phase difference. When the engine successfully starts (i.e., its speed is not less than the starting speed), the processor stops driving the switches in the bridge circuit, thus stopping the lithium battery from supplying power to the three-phase AC motor.

[0083] Once the internal combustion engine reaches a speed not less than the starting speed, the processor detects the polarity of the back electromotive force (EMF) of the three-phase AC motor and controls the switching on and off of each switch in the bridge circuit. This controls the AC back EMF of the three-phase AC motor to convert AC to DC, charging the lithium battery. Due to the presence of the winding inductance, lithium battery, and switching transistors in the three-phase AC motor, by reasonably controlling the on and off of each switch, the AC output from the three-phase AC motor can be rectified and boosted to obtain a stable DC power supply for charging the lithium battery.

[0084] It should be noted that the negative terminal of the DC bus between the lithium battery and the bridge circuit can also be equipped with a current detection device, which can be implemented by a high-precision power resistor or a Hall effect current sensor; this application does not limit this. When the processor controls the bridge circuit to control the output current of the three-phase AC motor, it can control the DC current output by the three-phase AC motor based on this bus current.

[0085] It should also be noted that, in order to avoid damage to the lithium battery when charging due to excessive output voltage from the bridge circuit, the charging voltage of the lithium battery needs to be monitored in real time to ensure that the output voltage of the bridge circuit is greater than the voltage of the lithium battery, but not greater than the maximum charging voltage.

[0086] Furthermore, the three-phase AC motor in this application increases the rotor size, wire diameter, and uses high-performance magnets compared to traditional magneto motors. Its stator consists of three-phase windings A, B, and C, and a neutral point N connected in a "star" configuration. The rotor consists of a flywheel and magnets attached to the inner side of the flywheel. Unlike the magnets in traditional magneto motors, the three-phase AC motor in this application uses high-performance magnets (rare earth). The magnets consist of multiple pairs of magnets with opposite magnetic properties attached to the inner side of the flywheel. This high-performance magnet gives the three-phase AC motor a large electromagnetic torque when operating as a motor, which is sufficient to drive the load.

[0087] For the back EMF rectification and boost control of the motor, this application implements the following control for the bridge circuit:

[0088] The control of the conduction and turn-off of the first switch G1 to the sixth switch G6 is divided into normally open (on), normally off (off), and modulation (PWM (Pulse Width Modulation)). The duty cycle of PWM can be adjusted according to the changes in the voltage and current of the DC output of the bridge circuit to achieve the requirement that the voltage of the DC output of the bridge circuit is greater than the voltage of the lithium battery and that constant current is output.

[0089] In this circuit, the first switch G1 and the fourth switch G4, the second switch G2 and the fifth switch G5, and the third switch G3 and the sixth switch G6 belong to the upper and lower sides of the same bridge arm, respectively, and cannot be turned on simultaneously. During control, completely complementary PWM signals need to be designed for the two switches belonging to the same bridge arm. That is, the high and low levels of the PWM signals for the first switch G1 and the fourth switch G4 are opposite; the high and low levels of the PWM signals for the second switch G2 and the fifth switch G5 are opposite; and the high and low levels of the PWM signals for the third switch G3 and the sixth switch G6 are opposite. Please refer to... Figure 3 , Figure 3 This is a schematic diagram of a complementary PWM signal provided by the present invention.

[0090] Please refer to the table below for details:

[0091] Table 1 Control signals for each switch in the bridge circuit.

[0092]

[0093]

[0094] In this circuit, the BC, AB, and CA phase line voltages are all sinusoidal voltages. In Table 1, a BC, AB, or CA phase line voltage of 1 indicates a voltage greater than 0, while a BC, AB, or CA phase line voltage of 0 indicates a voltage less than 0. G1-G6 represent the six switches in the bridge circuit. It can be seen that when the first switch G1 is normally closed, the fourth switch G4 is normally open; when the second switch G2 is normally closed, the fifth switch G5 is normally open; when the third switch G3 is normally closed, the sixth switch G6 is normally open. Furthermore, when a switch in one bridge arm is normally closed or normally open, it controls the switches in the other two bridge arms. A PWM signal with a duty cycle of 1 is sent to the normally open switching transistors, and a PWM signal with a duty cycle of 0 is sent to the normally closed switching transistors. The PWM signals sent to the switching transistors of other bridge arms ensure that the final DC voltage output by the bridge circuit is greater than the voltage of the lithium battery, and the DC current output is the preset current. In addition, the high and low levels of the PWM signals of the upper and lower switching transistors in the same bridge arm are exactly opposite. For example, when controlling the first switching transistor G1 and the fourth switching transistor G4 in the first bridge arm, the PWM signal sent to the first switching transistor G1 is high, while the PWM signal sent to the fourth switching transistor G4 is low, so as to avoid the two switching transistors in the same bridge arm being turned on at the same time, thus avoiding the bridge arm from being shot-through.

[0095] At low speeds, the smaller the torque ripple of the three-phase AC motor, the better it is for the stability of the internal combustion engine. Therefore, during power generation control, by controlling the three-phase AC motor to generate a sinusoidal phase current, the harmonics of the synthesized torque can be reduced, thereby reducing the generation of torque ripple, which is beneficial to the low-speed stability of the internal combustion engine, and thus reduces the vibration and noise of the entire vehicle.

[0096] In a three-phase bridge circuit composed of MOSFETs, the midpoint of each bridge arm is connected to a phase line of a three-phase AC motor, which can be equivalent to part of a boost chopper circuit. The entire bridge circuit is equivalent to three boost chopper circuits connected in parallel. Furthermore, due to the low on-resistance of MOSFETs, their losses are also low.

[0097] The following uses the line voltage state 001 in Table 1 as an example to illustrate the specific implementation details of this patent. Within one PWM cycle, the first switch G1 and the fourth switch G4, as well as the second switch G2 and the fifth switch G5, each have one on and one off switching. When the fourth switch G4 is on, the first switch G1 is off, the fifth switch G5 is on, and the second switch G2 is off, since the third switch G3 is off and the sixth switch G6 is on, please refer to... Figure 4 , Figure 4This is a schematic diagram of a bridge circuit in the control process provided by the present invention. The internal combustion engine drives a three-phase AC motor to rotate. The electrical energy of the induced electromotive force generated by the three-phase AC motor is partly converted into internal resistance heat energy, and the remaining part of the electrical energy is converted into magnetic field energy through the winding and stored in the winding inductance of the circuit.

[0098] When the first switch G1 is on, the fourth switch G4 is off, the second switch G2 is on, and the fifth switch G5 is off, since the third switch G3 is off and the sixth switch G6 is on, please refer to... Figure 5 , Figure 5 This is a schematic diagram of a bridge circuit in another control process provided by the present invention. Furthermore, the current in the three-phase AC motor windings cannot change abruptly. The current flows from the motor windings, through the first switch G1 to the positive terminal of the lithium battery, and then through the sixth switch G6 to the negative terminal of the lithium battery; or through the second switch G2 to the positive terminal of the lithium battery, and then through the sixth switch G6 to the negative terminal of the lithium battery, thus charging the lithium battery. By controlling a suitable PWM duty cycle, a stable DC current can be obtained.

[0099] As a preferred embodiment, it also includes:

[0100] Receive the first level signal corresponding to the line voltage of the CA phase of the three-phase AC motor sent by the first Hall sensor, so as to detect the line voltage of the CA phase;

[0101] Receive the second level signal corresponding to the line voltage of phases AB of the three-phase AC motor sent by the second Hall sensor, so as to detect the line voltage of phases AB;

[0102] The system receives a third-level signal corresponding to the line voltage of phases BC of the three-phase AC motor, sent by the third Hall sensor, to detect the line voltage of phases BC.

[0103] In order to detect the line voltage of the three-phase AC motor and control the various switching transistors in the bridge circuit accordingly, this application also includes Hall sensors. Three Hall sensors are respectively set at corresponding positions on the stator of the three-phase AC motor. The Hall sensors sense the electrical angle of the rotor rotation and convert the electrical angle of the rotor rotation into a level signal, so that the processor can detect the line voltage of each phase of the three-phase AC motor based on the level signal output by the Hall sensors.

[0104] Please refer to Figure 6 , Figure 6 This is a schematic diagram of the level signal output by a Hall sensor provided by the present invention. As can be seen, Figure 6There is a certain phase difference between the level signals output by any two Hall sensors. This is because there is a phase difference between the line voltages of the three-phase AC motor detected by any two Hall sensors. Since the line voltages of the three-phase AC motor are all sinusoidal voltages, the phase of the line voltages of the three-phase AC motor can be determined based on the level signals output by the Hall sensors.

[0105] Please refer to Figure 7 , Figure 7 This invention provides a schematic diagram of a management system for charging a lithium battery using a three-phase AC motor, applied to a bridge circuit located between the lithium battery and the three-phase AC motor; the system includes:

[0106] The first judgment unit 71 is used to determine whether the three-phase AC motor is currently in generator mode;

[0107] The second judgment unit 72 is used to determine whether the speed of the three-phase AC motor is less than the preset speed when the three-phase AC motor is in generator mode.

[0108] The control unit 73 is used to control each switch in the bridge circuit when the speed of the three-phase AC motor is less than the preset speed, so that the bridge circuit can boost and rectify the AC power output by the three-phase AC motor, and the voltage of the output DC power is within the preset charging voltage range, and the current of the DC power is the preset current.

[0109] The product of the DC current and voltage output by the bridge circuit shall not exceed the rated power of the three-phase AC motor.

[0110] For a description of the management system for charging a lithium battery using a three-phase AC motor provided by this invention, please refer to the above method embodiments; the invention itself will not be described again here.

[0111] Please refer to Figure 8 , Figure 8 This invention provides a schematic diagram of a management device for charging a lithium battery using a three-phase AC motor. The device includes:

[0112] Memory 81 is used to store computer programs;

[0113] The processor 82 is used to execute computer programs to implement the steps of the management method described above for charging a lithium battery using a three-phase AC motor.

[0114] For a description of the management device for charging a lithium battery using a three-phase AC motor provided by the present invention, please refer to the above method embodiments; the present invention will not be described again here.

[0115] As a preferred embodiment, it also includes:

[0116] A bridge circuit is installed between the lithium battery and the three-phase AC motor;

[0117] The bridge circuit includes a first switch G1 to a sixth switch G6. The first terminal of the first switch G1 is connected to the positive terminal of the lithium battery, and the second terminal is connected to the first terminal of the fourth switch G4. The second terminal of the fourth switch G4 is connected to the negative terminal of the lithium battery. The first terminal of the second switch G2 is connected to the positive terminal of the lithium battery, and the second terminal is connected to the first terminal of the fifth switch G5. The second terminal of the fifth switch G5 is connected to the negative terminal of the lithium battery. The first terminal of the third switch G3 is connected to the positive terminal of the lithium battery, and the second terminal is connected to the first terminal of the sixth switch G6. The second terminal of the sixth switch G6 is connected to the negative terminal of the lithium battery. The second terminals of the first switch G1 and the first terminal of the fourth switch G4 are connected to the A-phase winding of the three-phase AC motor. The second terminals of the second switch G2 and the first terminals of the fifth switch G5 are connected to the B-phase winding of the three-phase AC motor. The second terminals of the third switch G3 and the first terminals of the sixth switch G6 are connected to the C-phase winding of the three-phase AC motor. The third terminals of the first to sixth switches are their respective control terminals.

[0118] In a preferred embodiment, the system further includes a first Hall sensor, a second Hall sensor, and a third Hall sensor disposed between the three-phase AC motor and the processor.

[0119] The first Hall sensor is used to detect the line voltage of the CA phase of the three-phase AC motor. It outputs a low level when the line voltage of the CA phase of the three-phase AC motor crosses zero from negative to positive until the line voltage of the CA phase crosses zero from positive to negative. It outputs a high level when the line voltage of the CA phase of the three-phase AC motor crosses zero from positive to negative until the line voltage of the CA phase crosses zero from negative to positive.

[0120] The second Hall sensor is used to detect the line voltage of phases AB of the three-phase AC motor. It outputs a low level when the line voltage of phases AB of the three-phase AC motor crosses zero from negative to positive until the line voltage of phases AB of the three-phase AC motor crosses zero from positive to negative. It outputs a high level when the line voltage of phases AB of the three-phase AC motor crosses zero from positive to negative until the line voltage of phases AB of the three-phase AC motor crosses zero from negative to positive.

[0121] The third Hall sensor is used to detect the line voltage of phases BC of a three-phase AC motor. It outputs a low level when the line voltage of phases BC of the three-phase AC motor crosses zero from negative to positive until it crosses zero from positive to negative. It outputs a high level when the line voltage of phases BC of the three-phase AC motor crosses zero from positive to negative until it crosses zero from negative to positive.

[0122] Please refer to Figure 9 , Figure 9 This is a schematic diagram of the specific structure of a management device for charging a lithium battery using a three-phase AC motor, as provided by the present invention.

[0123] Please refer to Figure 10 , Figure 10 This is a schematic diagram of the level signal output by a Hall sensor provided by the present invention. Figure 10 This shows the correspondence between the line voltage of phase AB and the level signal output by the second Hall sensor. Taking this as an example, the line voltages of the other two phases are similar to those of phase AB.

[0124] Please refer to Figure 11 , Figure 11 This is a schematic diagram of phase current and phase voltage modulation waveforms provided by the present invention. (Through...) Figure 11 As can be seen, through the control method of the present invention, the phase current of the three-phase AC motor is a sinusoidal current and the phase voltage is a rectangular wave voltage.

[0125] The computer-readable storage medium of the present invention stores a computer program, which, when executed by the processor 32, implements the steps of the management method for charging a lithium battery using a three-phase AC motor as described above.

[0126] For a description of the computer-readable storage medium provided by the present invention, please refer to the above method embodiments; the present invention will not be described again here.

[0127] It should also be noted that, in this specification, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0128] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. 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 the invention. Therefore, the invention 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 method of managing charging of a lithium battery by a three-phase alternating current motor, characterized in that, The application is applied to a bridge circuit arranged between a lithium battery and a three-phase AC motor; the method comprises: judging whether the three-phase AC motor is currently in a generator state; if in the generator state, judging whether the rotating speed of the three-phase AC motor is less than a preset rotating speed; if less than the preset rotating speed, controlling each switch tube in the bridge circuit to make the bridge circuit step-up rectify the AC power output by the three-phase AC motor, and the voltage of the output DC power is within a preset charging voltage range of the lithium battery, and the current of the DC power is a preset current, so that the three-phase AC motor outputs the power in a variable-voltage constant-current manner to charge the lithium battery; the product of the current and the voltage of the DC power output by the bridge circuit is not greater than the rated power of the three-phase AC motor; controlling each switch tube in the bridge circuit comprises: controlling the conduction and the turn-off of each switch tube by detecting the polarity of the counter electromotive force of the three-phase AC motor; after the three-phase AC motor drags the internal combustion engine to a certain rotating speed, if the rotating speed of the internal combustion engine is not less than a starting rotating speed, the polarity of the counter electromotive force of the three-phase AC motor is detected, and the conduction and the turn-off of each switch tube in the bridge circuit are controlled again to control the AC counter electromotive force of the three-phase AC motor to perform AC-to-DC conversion to charge the lithium battery; the bridge circuit comprises a first bridge arm connected with an A-phase coil of the three-phase AC motor, a second bridge arm connected with a B-phase coil of the three-phase AC motor, and a third bridge arm connected with a C-phase coil of the three-phase AC motor; each switch tube in each bridge arm of the bridge circuit is controlled in sequence to make the bridge circuit step-up rectify the AC power output by the three-phase AC motor, and the voltage of the output DC power is within the preset charging voltage range, and the current of the DC power is the preset current; the first bridge arm comprises a first switch tube and a fourth switch tube, the second bridge arm comprises a second switch tube and a fifth switch tube, and the third bridge arm comprises a third switch tube and a sixth switch tube; a first end of the first switch tube is connected with a positive electrode of the lithium battery, and a second end is connected with a first end of the fourth switch tube; a second end of the fourth switch tube is connected with a negative electrode of the lithium battery; a first end of the second switch tube is connected with the positive electrode of the lithium battery, and a second end is connected with a first end of the fifth switch tube; a second end of the fifth switch tube is connected with the negative electrode of the lithium battery; a first end of the third switch tube is connected with the positive electrode of the lithium battery, and a second end is connected with a first end of the sixth switch tube; a second end of the sixth switch tube is connected with the negative electrode of the lithium battery; a second end of the first switch tube and a first end of the fourth switch tube are connected with an A-phase winding of the three-phase AC motor; a second end of the second switch tube and a first end of the fifth switch tube are connected with a B-phase winding of the three-phase AC motor; a second end of the third switch tube and a first end of the sixth switch tube are connected with a C-phase winding of the three-phase AC motor; third ends of the first switch tube to the sixth switch tube are control ends respectively; When the three-phase alternating current motor is in a generator state, and a line voltage of a CA phase of the three-phase alternating current motor is greater than zero, the third switch tube is controlled to be always closed, and the sixth switch tube is controlled to be always open; when a line voltage of an AB phase of the three-phase alternating current motor is greater than zero, the first switch tube is controlled to be always closed, and the fourth switch tube is controlled to be always open; when a line voltage of a BC phase of the three-phase alternating current motor is greater than zero, the second switch tube is controlled to be always closed, and the fifth switch tube is controlled to be always open; The PWM signal is output to the control end of the switch tube which is not in the always closed or always open state, and the duty cycle of the PWM signal is adjusted, so that the voltage of the direct current output by the bridge circuit is in the preset charging voltage range, the current of the direct current is a preset current, and the high and low levels of the PWM signal of the first switch tube and the fourth switch tube are opposite, the high and low levels of the PWM signal of the second switch tube and the fifth switch tube are opposite, and the high and low levels of the PWM signal of the third switch tube and the sixth switch tube are opposite.

2. The method of claim 1, wherein the three-phase AC motor is a lithium battery charger. Further comprising: Receiving a first level signal corresponding to the line voltage of the CA phase of the three-phase alternating current motor sent by the first Hall sensor to detect the line voltage of the CA phase; Receiving a second level signal corresponding to the line voltage of the AB phase of the three-phase alternating current motor sent by the second Hall sensor to detect the line voltage of the AB phase; Receiving a third level signal corresponding to the line voltage of the BC phase of the three-phase alternating current motor sent by the third Hall sensor to detect the line voltage of the BC phase.

3. A management system for charging a lithium battery with a three-phase alternating current motor, characterized by, The system is applied to a bridge circuit arranged between a lithium battery and a three-phase alternating current motor; the system comprises: A first judging unit is configured to judge whether the three-phase alternating current motor is currently in a generator state; A second judging unit is configured to, when the three-phase alternating current motor is in the generator state, judge whether the rotating speed of the three-phase alternating current motor is less than a preset rotating speed; A control unit is configured to, when the rotating speed of the three-phase alternating current motor is less than the preset rotating speed, control each switch tube in the bridge circuit, so that the bridge circuit steps up and rectifies alternating current output by the three-phase alternating current motor, and the voltage of the direct current output is in a preset charging voltage range, and the current of the direct current is a preset current, so that the three-phase alternating current motor outputs alternating current in a variable-voltage constant-current manner to charge the lithium battery; The product of the current and the voltage of the direct current output by the bridge circuit is not greater than the rated power of the three-phase alternating current motor; The control unit is specifically configured to control the conduction and the turn-off of each switch tube by detecting the polarity of the counter electromotive force of the three-phase alternating current motor; The control unit is further configured to, after the three-phase alternating current motor drags the internal combustion engine to a certain rotating speed, if the rotating speed of the internal combustion engine is not less than a starting rotating speed, detect the polarity of the counter electromotive force of the three-phase alternating current motor, and control the conduction and the turn-off of each switch tube in the bridge circuit again to control the alternating counter electromotive force of the three-phase alternating current motor to perform alternating-to-direct current conversion to charge the lithium battery. The bridge circuit comprises a first bridge arm connected with an A-phase coil of the three-phase AC motor, a second bridge arm connected with a B-phase coil of the three-phase AC motor, and a third bridge arm connected with a C-phase coil of the three-phase AC motor; The control unit is specifically configured to control each switch tube in each bridge arm of the bridge circuit in sequence, so that the bridge circuit boosts and rectifies the AC power output by the three-phase AC motor, and the voltage of the DC power output is within the preset charging voltage range, and the current of the DC power is a preset current; The first bridge arm comprises a first switch tube and a fourth switch tube, the second bridge arm comprises a second switch tube and a fifth switch tube, and the third bridge arm comprises a third switch tube and a sixth switch tube; a first end of the first switch tube is connected with a positive electrode of the lithium battery, and a second end thereof is connected with a first end of the fourth switch tube; a second end of the fourth switch tube is connected with a negative electrode of the lithium battery; a first end of the second switch tube is connected with the positive electrode of the lithium battery, and a second end thereof is connected with a first end of the fifth switch tube; a second end of the fifth switch tube is connected with the negative electrode of the lithium battery; a first end of the third switch tube is connected with the positive electrode of the lithium battery, and a second end thereof is connected with a first end of the sixth switch tube; a second end of the sixth switch tube is connected with the negative electrode of the lithium battery; a second end of the first switch tube and a first end of the fourth switch tube are connected with an A-phase winding of the three-phase AC motor; a second end of the second switch tube and a first end of the fifth switch tube are connected with a B-phase winding of the three-phase AC motor; a second end of the third switch tube and a first end of the sixth switch tube are connected with a C-phase winding of the three-phase AC motor; and third ends of the first switch tube to the sixth switch tube are control ends of the first switch tube to the sixth switch tube, respectively; The control unit is specifically configured to, when the three-phase AC motor is in a generator state and a line voltage of a CA phase of the three-phase AC motor is greater than zero, control the third switch tube to be always closed and control the sixth switch tube to be always open; when a line voltage of an AB phase of the three-phase AC motor is greater than zero, control the first switch tube to be always closed and control the fourth switch tube to be always open; and when a line voltage of a BC phase of the three-phase AC motor is greater than zero, control the second switch tube to be always closed and control the fifth switch tube to be always open; The control unit is specifically configured to output a PWM signal to a control end of a switch tube that is not in an always-closed or always-open state, adjust a duty cycle of the PWM signal, so that the voltage of the DC power output by the bridge circuit is within the preset charging voltage range, the current of the DC power is a preset current, and the high and low levels of the PWM signal of the first switch tube and the fourth switch tube are opposite, the high and low levels of the PWM signal of the second switch tube and the fifth switch tube are opposite, and the high and low levels of the PWM signal of the third switch tube and the sixth switch tube are opposite.

4. A management device for charging a lithium battery with a three-phase alternating current motor, characterized by Comprise: a memory for storing a computer program; a processor for executing the computer program to implement the steps of the management method when the three-phase AC motor charges the lithium battery according to any one of claims 1 to 2; Further comprise: a bridge circuit arranged between the lithium battery and the three-phase AC motor; The bridge circuit comprises first to sixth switch tubes, a first end of the first switch tube is connected with a positive electrode of a lithium battery, a second end is connected with a first end of a fourth switch tube, a second end of the fourth switch tube is connected with a negative electrode of the lithium battery; a first end of the second switch tube is connected with the positive electrode of the lithium battery, a second end is connected with a first end of a fifth switch tube, a second end of the fifth switch tube is connected with the negative electrode of the lithium battery; a first end of the third switch tube is connected with the positive electrode of the lithium battery, a second end is connected with a first end of a sixth switch tube, a second end of the sixth switch tube is connected with the negative electrode of the lithium battery; the second end of the first switch tube and the first end of the fourth switch tube are connected with an A-phase winding of a three-phase AC motor; the second end of the second switch tube and the first end of the fifth switch tube are connected with a B-phase winding of the three-phase AC motor; the second end of the third switch tube and the first end of the sixth switch tube are connected with a C-phase winding of the three-phase AC motor; third ends of the first to sixth switch tubes are control ends respectively.

5. The apparatus for managing charging of a lithium battery with a three-phase alternating current motor as claimed in claim 4, wherein Further comprising first, second and third Hall sensors arranged between the three-phase AC motor and the processor; The first Hall sensor is used for detecting a line voltage of a CA phase of the three-phase AC motor, and outputs a low level when the line voltage of the CA phase of the three-phase AC motor passes zero point from negative to positive until the line voltage of the CA phase passes zero point from positive to negative, and outputs a high level when the line voltage of the CA phase of the three-phase AC motor passes zero point from positive to negative until the line voltage of the CA phase passes zero point from negative to positive; The second Hall sensor is used for detecting a line voltage of an AB phase of the three-phase AC motor, and outputs a low level when the line voltage of the AB phase of the three-phase AC motor passes zero point from negative to positive until the line voltage of the AB phase passes zero point from positive to negative, and outputs a high level when the line voltage of the AB phase of the three-phase AC motor passes zero point from positive to negative until the line voltage of the AB phase passes zero point from negative to positive; The third Hall sensor is used for detecting a line voltage of a BC phase of the three-phase AC motor, and outputs a low level when the line voltage of the BC phase of the three-phase AC motor passes zero point from negative to positive until the line voltage of the BC phase passes zero point from positive to negative, and outputs a high level when the line voltage of the BC phase of the three-phase AC motor passes zero point from positive to negative until the line voltage of the BC phase passes zero point from negative to positive.

6. A computer readable storage medium characterized by The computer readable storage medium stores a computer program, and the computer program is executed by the processor to realize the steps of the management method for charging the lithium battery by the three-phase AC motor according to any one of claims 1 to 2.

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