Motor three-phase winding active short circuit control system and method

Abstract

The invention relates to the field of motor control methods, in particular to a motor three-phase winding active short circuit control system and method. A pump capacitor; the drain electrodes of the three first power tubes are connected to the switch, the source electrodes of the three first power tubes are connected to the three-phase driving end of the motor, and the switch is driven by the controller and is switched between the positive electrode of the battery and the pump capacitor; the drain electrodes of the three second power tubes are respectively connected to the three-phase driving end of the motor, and the source electrodes of the three second power tubes are connected to the battery; the drain electrode of the third power tube is connected between the switch and the battery, and the source electrode of the third power tube is connected to the pump capacitor; the drain electrode of the fourth power tube is connected between the pump capacitor and the third power tube, and the source electrode of the fourth power tube is connected to the battery; a controller outputs PWM signals to grid electrodes of three first power tubes and grid electrodes of three second power tubes respectively, and the PWM signals output to the three first power tubes are input to a grid electrode of a third power tube after passing through a logic buffer and a first optical isolator and then are input to a grid electrode of a fourth power tube after passing through a phase inverter and a second optical isolator; source electrodes of the three first power tubes, the three second power tubes, the third power tube and the fourth power tube are respectively connected with positive electrodes of different first diodes, and drain electrodes of the three first power tubes, the three second power tubes, the third power tube and the fourth power tube are connected with negative electrodes of the first diodes. By accurately controlling and optimizing the current path, the braking performance is improved, the parking time is shortened, and more efficient energy recovery is achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of motor control methods, and particularly to a three-phase winding active short-circuit control system and method for a motor. Background Art

[0002] With the rapid development of fields such as electric vehicles (EV) and electric bicycles (EBike), the control technology of electric motors has become increasingly important, especially in the braking technology of electric motors. Traditional braking systems mainly rely on mechanical braking or resistive braking to decelerate. Although these methods are simple, they have low efficiency and problems of energy waste. In order to improve the braking performance and energy recovery efficiency of electric motors, more and more research has focused on using the back electromotive force (back EMF) of the electric motor itself for energy recovery and enhancing the braking effect.

[0003] However, the existing back EMF braking systems face two main challenges: 1. Long braking time: Traditional energy recovery and braking methods have poor effects during low-speed braking, resulting in a long braking time, which affects the safety and user experience of the vehicle.

[0004] 2. Insufficient braking torque: Although the back EMF can provide a certain braking torque, in high-load or emergency braking situations, its braking torque is insufficient, resulting in an unsatisfactory parking effect.

[0005] Therefore, how to effectively utilize the back EMF of the electric motor, through precise control and optimization of the current path, to improve the braking performance, shorten the parking time, and achieve more efficient energy recovery has become an important issue in the electric motor control technology. Summary of the Invention

[0006] In view of the above technical problems, the present invention provides a three-phase winding active short-circuit control system and method for a motor, which improves the braking performance, shortens the parking time, and achieves more efficient energy recovery through precise control and optimization of the current path.

[0007] Other features and advantages of the present disclosure will become apparent through the following detailed description, or be partially learned through the practice of the present disclosure.

[0008] According to one aspect of the present invention, a three-phase winding active short-circuit control system for a motor is proposed. The system includes: A battery; A pump capacitor; Three first power transistors, the drains of the three first power transistors are connected to a switch, and the sources are respectively connected to the three-phase drive ends of the motor. The switch is driven by a controller and switches between the positive pole of the battery and the pump capacitor; Three second power transistors, the drains of the three second power transistors are respectively connected to the three-phase drive terminals of the motor, and the sources are connected to the battery; A third power transistor, the drain of the third power transistor is connected between the switch and the battery, and its source is connected to the pump capacitor; A fourth power transistor, the drain of the fourth power transistor is connected between the pump capacitor and the third power transistor, and its source is connected to the battery; The controller respectively outputs PWM signals to the gates of the three first power transistors and the three second power transistors. The PWM signals output to the three first power transistors pass through a logic buffer and a first opto-isolator and then are input to the gate of the third power transistor. And the PWM signals output to the three first power transistors pass through a logic buffer and then through an inverter and a second opto-isolator and are input to the gate of the fourth power transistor; The sources of the three first power transistors, the three second power transistors, the third power transistor, and the fourth power transistor are respectively connected to the anodes of different first diodes, and the drains are connected to the cathodes of the first diodes.

[0009] Further, the system further includes a second diode. The anode of the second diode is connected to the drain of the fourth power transistor, and its cathode is connected to the source of the third power transistor. A braking resistor is connected in parallel with the second diode.

[0010] According to a second aspect of the present disclosure, there is provided a method for actively short-circuiting a three-phase winding of a motor, characterized in that the method includes the system according to any one of claims 1-2, and the method includes; When the controller receives a throttle signal, the switch is connected to the battery. The controller adjusts the duty cycle and modulation frequency of the PWM signals output to the three first power transistors and the three second power transistors according to the throttle signal, so that the three-phase current output by the inverter is sequentially input to the three-phase windings of the motor; When the controller receives a braking signal, the switch is connected to the pump capacitor and disconnected from the battery, and the third power transistor and the fourth power transistor are alternately turned off and on. The voltages of the pump capacitor and the battery are serially superimposed through the first diode connected in parallel with the third power transistor, and the superimposed voltage accelerates the motor to stop rotating.

[0011] Further, when the controller receives a braking signal, the method further includes: Obtain the Hall data output by three Hall sensors on the three-phase windings of the motor, and obtain the Hall data to obtain the sector position where the rotor of the motor is located; According to the sector position, adjust the duty cycle and switching sequence of the PWM signals output to the first power transistor and the second power transistor, so that the back electromotive force of the motor reaches the maximum reverse torque, so as to stop the forward rotation of the motor.

[0012] The technical solution of the present disclosure has the following beneficial effects: By short-circuiting the first power transistor and the second power transistor to charge the pump capacitor, and the pump capacitor is used as an additional energy source to be connected in series with the battery to superimpose the voltage, the braking torque can be increased during braking, and the rotating motor can be stopped in an effective manner, reducing the braking time. Description of the Drawings

[0013] Figure 1 It is a schematic diagram of an active short-circuit control system for a three-phase winding of a motor in an embodiment of this specification; Figure 2 It is a schematic diagram of the control of the third power transistor and the fourth power transistor in an embodiment of this specification; Figure 3 It is a Hall table of the switching sequence of the first power transistor and the second power transistor in an embodiment of this specification; Figure 4 It is a drive schematic diagram of an electric vehicle for implementing an active short-circuit control system for a three-phase winding of a motor in an embodiment of this specification; Figure 5 It is a flowchart of a method for actively short-circuiting a three-phase winding of a motor stored in an embodiment of this specification. Detailed Embodiments

[0014] Example embodiments will now be described more fully with reference to the accompanying drawings. However, the example embodiments can be implemented in various forms and should not be construed as limited to the examples set forth herein; rather, these embodiments are provided so that this disclosure will be more complete and comprehensive, and will fully convey the concept of the example embodiments to those skilled in the art. The features, structures, or characteristics described may be combined in any suitable manner in one or more embodiments. In the following description, numerous specific details are provided to give a thorough understanding of the embodiments of the present disclosure. However, those skilled in the art will realize that the technical solutions of the present disclosure can be practiced without one or more of the specific details, or other methods, components, devices, steps, etc. may be used. In other cases, well-known technical solutions are not shown or described in detail to avoid obscuring the various aspects of the present disclosure.

[0015] In addition, the accompanying drawings are only schematic illustrations of the present disclosure. The same reference numerals in the drawings denote the same or similar parts, and thus repeated descriptions thereof will be omitted. Some of the block diagrams shown in the drawings are functional entities, which do not necessarily correspond to physically or logically independent entities. These functional entities can be implemented in software form, or implemented in one or more hardware modules or integrated circuits, or implemented in different networks and / or processor devices and / or microcontroller devices.

[0016] The present invention provides an active short - circuit control system for the three - phase windings of a product motor. Referring to Figure 1 As shown, an active short - circuit control system for the three - phase windings of a motor, the system includes: Battery Vba; Pump capacitor C; Three first power transistors S1, S3, S5. The drains of the three first power transistors are connected to the switch RLY, and the sources are respectively connected to the three - phase drive ends of the motor PMSM. The switch RLY is driven by a controller and switches between the positive pole of the battery Vba and the pump capacitor C; Three second power transistors S2, S4, S6. The drains of the three second power transistors are respectively connected to the three - phase drive ends of the motor PMSM, and the sources are connected to the battery Vba; A third power transistor S8. The drain of the third power transistor S8 is connected between the switch RLY and the battery Vba, and its source is connected to the pump capacitor C; A fourth power transistor S7. The drain of the fourth power transistor S7 is connected between the pump capacitor C and the third power transistor S8, and its source is connected to the battery Vba; The controller respectively outputs PWM signals to the gates of the three first power transistors S1, S3, S5, the three second power transistors S2, S4, S6. The PWM signals output to the three first power transistors S1, S3, S5 pass through a logic buffer 101 and a first opto - isolator 102 and then are input to the gate of the third power transistor S8. And, the PWM signals output to the three first power transistors S1, S3, S5 pass through a logic buffer 101 and then pass through an inverter 103 and a second opto - isolator 104 and are input to the gate of the fourth power transistor S7; The sources of the three first power transistors S1, S3, S5, the three second power transistors S2, S4, S6, the third power transistor S8, and the fourth power transistor S7 are respectively connected to the positive poles of different first diodes, and the drains are connected to the negative poles of the first diodes. Exemplarily, the first diodes connected in parallel with the second power transistors S2, S4, S6 are D2, D4, D6 respectively.

[0017] Among them, the proposed control system is based on the back electromotive force regenerated by a free-running motor, and the electromotive force is utilized in an efficient manner to generate a braking torque. In this embodiment, the back electromotive force is stored in the pump capacitor C, and the pump capacitor C is connected to the battery Vba in a series-parallel configuration, thereby instantaneously increasing the braking force and extending the braking action time. The back electromotive force controlled by the PWM signal is fed back to the pump capacitor C as an additional energy source, and then cascaded with the vehicle battery to provide an additional braking torque to stop the rotating permanent magnet synchronous motor (PMSM).

[0018] The system further includes a second diode Dr, the anode of the second diode Dr is connected to the drain of the fourth power transistor S7, its cathode is connected to the source of the third power transistor S8, and a braking resistor R is connected in parallel with the second diode Dr. In this circuit, the pump capacitor C serves as a charge pump to store the back electromotive force for high-energy charge storage, and the braking resistor R consumes energy when the pump capacitor C is charged.

[0019] The activation of the system is controlled by a braking signal. When the circuit is operating, the PWM signals PWM1, PWM3, and PWM5 corresponding to the three first power transistors are only activated as logic buffers. The three first power transistors are turned off to direct the braking current through the body diodes of the power transistors. Referring to Figure 2 , the control signals of the first power transistors S1, S3, and S5 are combined and then transmitted to the first opto-isolator 102 to control the third power transistor S8. In addition, this signal is also transmitted to an inverter. The inverter inverts the signal, if the input is 1, the output becomes 0, and it is used to control the fourth power transistor S7.

[0020] In the braking mode, the switch cuts off the drive circuit and executes the braking circuit. The controller turns on the fourth power transistor S7 and turns off the third power transistor S8, so that the back electromotive force generated by the motor generates a current. Referring to Figure 1 , the back electromotive force is rectified into a DC voltage through the body diode of the fourth power transistor S7. In Figure 1 , the voltage of the pump capacitor C is Vc, the voltage of the battery is Vba, the voltages between the fourth power transistor S7 and the third power transistor S8 are Vs7 and Vs8 respectively, the braking resistor is R, the internal resistance of the motor is Rm, the internal inductance of the motor is Lm, and the internal capacitance of the motor is Cm.

[0021] The controller is activated and deactivated by the braking signal. When the controller is working, PWM1, PWM3, and PWM5 are combined to control the logic buffer. After the output signals of the logic buffer are combined, they are used to isolate the braking signal from other signals and transmit it to the first opto-isolator to control the third power transistor S8. In addition, this signal is also used to activate the inverter and connect to the second opto-isolator to control the fourth power transistor S7.

[0022] Specifically, when the electric vehicle is in the driving mode, the force direction of the rotor magnetic field is clockwise. When the electric vehicle is in the braking mode, the force direction of the rotor magnetic field becomes counterclockwise. After the braking mode, when the third power transistor S8 is turned off and the fourth power transistor S7 is turned on, the pump capacitor is charged at this time, and the motor, the switch, the pump capacitor, the braking resistor, and the fourth power transistor S7 form a loop; after the third power transistor S8 is turned on and the fourth power transistor S7 is turned off, the motor, the switch, the pump capacitor, the third power transistor S8, and the battery form a loop, and the voltages of the pump capacitor and the motor are superimposed to start braking the motor. In order to effectively brake the PMSM motor in the shortest time, the switching sequence Hall table of the first power transistor and the second power transistor can be used to control the reverse magnetic field, as Figure 3 shown. The rotor position of the motor is determined by the output of the Hall sensors (Hall A, B, C), and the duty cycles of the PWM signals of the corresponding first power transistor and second power transistor are controlled. Among them, the PWM signals are used to adjust the switching states of the first power transistor and the second power transistor to achieve the smooth operation of the motor.

[0023] Among them, Figure 4 shows the schematic diagram of the entire system, where the controller is implemented by a 16-bit digital signal controller. The rotor position is detected by Hall sensors. The three-phase inverter is combined with the control system, and the braking signal is detected by a limit switch connected to the brake handle lever. The controller detects the throttle and brake signals to determine the operating mode and calculates the Hall signals to calculate the wheel speed. When driving, the controller calculates the PID control command by comparing the throttle command with the wheel speed signal, which is used to change the duty cycles of the PWM signals of the first power transistor and the second power transistor. When braking, the controller sends a command to cut off the current driving loop, so that the battery is connected to the pump capacitor, and the pump capacitor is charged through the back electromotive force, and the stacked voltage is then used to brake the motor with a fixed PWM signal duty cycle, as Figure 3 shown in the switching sequence of the first power transistor and the second power transistor.

[0024] Based on the same idea, as Figure 5 shown, a method for active short-circuit control of a three-phase winding of a motor is provided, and the method includes steps S201-202; In step S201, when the controller receives the throttle signal, the switch is connected to the battery, and the controller adjusts the duty cycles and modulation frequencies of the PWM signals output to the three first power transistors and the three second power transistors according to the throttle signal, so that the three-phase current output by the inverter is sequentially input to the three-phase windings of the motor; In step S202, when the controller receives a braking signal, the switcher is connected to the pump capacitor and disconnected from the battery, and the third power transistor and the fourth power transistor are alternately turned off and on. The voltages of the pump capacitor and the battery are serially superimposed through the first diode connected in parallel with the third power transistor, and the superimposed voltage accelerates the motor to stop rotating.

[0025] Wherein, when the controller receives a braking signal, the method further includes: Obtaining Hall data output by three Hall sensors on the three-phase windings of the motor, and obtaining the sector position where the rotor of the motor is located according to the Hall data; According to the sector position, adjusting the duty cycle and switching sequence of the PWM signals output to the first power transistor and the second power transistor, so that the back electromotive force of the motor reaches the maximum reverse torque, so as to stop the motor from rotating forward.

[0026] Beneficial effects: By short-circuiting the first power transistor and the second power transistor to charge the pump capacitor, and using the pump capacitor as an additional energy source to serially superimpose the voltage with the battery, the braking torque can be increased during braking, and the rotating motor can be effectively stopped, reducing the braking time.

[0027] The specific details of each module / unit in the above method have been described in detail in the implementation manners of the system part. The details not disclosed can be referred to the implementation manners of the system part, and thus will not be elaborated here.

[0028] After considering the specification and practicing the invention disclosed herein, those skilled in the art will readily think of other embodiments of the present disclosure. This application is intended to cover any variations, uses, or adaptations of the present disclosure, which follow the general principles of the present disclosure and include common general knowledge or conventional technical means in the technical field not disclosed in the present disclosure. The specification and embodiments are only regarded as exemplary, and the true scope and spirit of the present disclosure are pointed out by the claims.

[0029] It should be understood that the present disclosure is not limited to the exact structures described above and shown in the drawings, and various modifications and changes can be made without departing from its scope. The scope of the present disclosure is only limited by the appended claims.

Claims

1. A three-phase winding active short-circuit control system for a motor, characterized in that: The system comprises: Battery; Pump capacitor; Three first power tubes, the drain electrodes of the three first power tubes are connected to the switch, and the sources are respectively connected to the three-phase drive ends of the motor, the switch is driven by a controller, and switches between the positive electrode of the battery and the pump capacitor; Three second power tubes, wherein the drain electrodes of the three second power tubes are respectively connected to the three-phase driving ends of the motor, and the source electrodes are connected to the battery; a third power tube, wherein the drain of the third power tube is connected between the switch and the battery, and the source of the third power tube is connected to the pump capacitor; a fourth power tube, wherein a drain of the fourth power tube is connected between the pump capacitor and the third power tube, and a source of the fourth power tube is connected to the battery; The controller outputs PWM signals to the gates of the three first power tubes and the three second power tubes respectively, and the PWM signals output to the three first power tubes are input to the gate of the third power tube after passing through a logic buffer and a first optical isolator, and the PWM signals output to the three first power tubes are input to the gate of the fourth power tube after passing through a logic buffer, an inverter and a second optical isolator; The sources of the three first power tubes, the three second power tubes, the third power tube, and the fourth power tube are respectively connected to the anodes of different first diodes, and the drains are connected to the cathode of the first diode.

2. The motor three-phase winding active short-circuit control system according to claim 1 is characterized in that: The system further comprises a second diode, wherein the anode of the second diode is connected to the drain of the fourth power tube, the cathode of the second diode is connected to the source of the third power tube, and a braking resistor is connected in parallel with the second diode.

3. A method for actively controlling short circuit of three-phase windings of a motor, characterized in that: The method comprises a system as claimed in any one of claims 1-2, the method comprising; When the controller receives a throttle signal, the switch is connected to the battery, and the controller adjusts the duty ratio and the adjustment frequency of the PWM signal output to the three first power tubes and the three second power tubes according to the throttle signal, so that the three-phase current output by the inverter is sequentially input to the three-phase winding of the motor; When the controller receives a braking signal, the switch is connected to the pump capacitor and disconnected from the battery, and causes the third power tube and the fourth power tube to be alternately turned off and on. The voltage of the pump capacitor and the battery is connected in series through the first diode in parallel with the third power tube to achieve a superimposed voltage, and the superimposed voltage accelerates the motor to stop rotating.

4. The motor three-phase winding active short-circuit control method according to claim 3, characterized in that: When the controller receives a braking signal, the method further includes: Acquire Hall data output by three Hall sensors on the three-phase winding of the motor, acquire the Hall data, and obtain the sector position where the rotor of the motor is located; According to the sector position, the duty cycle and switching sequence of the PWM signal output to the first power tube and the second power tube are regulated so that the reverse electromotive force of the motor reaches the maximum reverse torque, so that the motor stops forward rotation.

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