High-precision control of permanent magnet synchronous motor control system and method

Abstract

The present invention discloses a high-precision controlled permanent magnet synchronous motor control system, including a three-phase inverter circuit, whose input end is connected to a DC power supply, and the output end of the three-phase inverter circuit is connected to the three-phase stator winding of the permanent magnet synchronous motor; an absorption circuit, and the upper and lower bridge arms of the three-phase inverter circuit are each connected in parallel with an absorption circuit; an energy storage capacitor, which is connected in parallel at both ends of the absorption circuit, and the upper and lower energy storage capacitors are connected in series through a first switch T4, and the positive poles of the two energy storage capacitors arranged in series are connected to the positive end of the DC power supply through a second switch T5, and the negative poles of the two energy storage capacitors arranged in series are connected to the negative end of the DC power supply through a third switch T7. The present invention effectively absorbs the impact of back electromotive force on the inverter circuit, and stores part of the back electromotive force energy in the energy storage capacitor, providing a high starting voltage for motor starting, realizing the rapid starting of the motor, and improving the control accuracy of the electric motor.

Description

Technical Field

[0001] The present invention relates to the technical field of motor control, and in particular to a high-precision control system and method for a permanent magnet synchronous motor. Background Art

[0002] In the prior art, when controlling the motor, the inverter bridge arm needs to be continuously switched on and off, resulting in back electromotive force generated on the off phase, which interferes with the motor control; at the same time, in the prior art, the motor starting speed is slow, which is not conducive to the precise control of the motor. Summary of the invention

[0003] An object of the present invention is to solve at least the above problems and to provide at least the advantages which will be described hereinafter.

[0004] Another object of the present invention is to provide a high-precision controlled permanent magnet synchronous motor control system and method, which absorbs the impact of back electromotive force on the inverter circuit and stores part of the back electromotive force energy in the energy storage capacitor, providing a high starting voltage for the motor to start, realize the rapid starting of the motor, and improve the control accuracy of the motor.

[0005] In order to achieve these purposes and other advantages according to the present invention, a high-precision controlled permanent magnet synchronous motor control system is provided, comprising:

[0006] A three-phase inverter circuit, an input end of which is connected to a DC power supply, and an output end of the three-phase inverter circuit is connected to a three-phase stator winding of a permanent magnet synchronous motor;

[0007] An absorption circuit, wherein the two ends of the upper and lower bridge arms of the three-phase inverter circuit are each connected in parallel with the absorption circuit;

[0008] The energy storage capacitor is connected in parallel at both ends of the absorption circuit. The upper and lower energy storage capacitors are connected in series through a first switch T4. The positive electrodes of the two energy storage capacitors arranged in series are connected to the positive terminal of the DC power supply through a second switch T5. The negative electrodes of the two energy storage capacitors arranged in series are connected to the negative terminal of the DC power supply through a third switch T7.

[0009] Preferably, the absorption circuit includes a plurality of absorption capacitors arranged in parallel, an energy-consuming resistor is arranged in parallel between every two of the absorption capacitors, the positive electrode of the absorption capacitor is connected to the outside through a fourth switch Tq, the negative electrode of the absorption capacitor is connected to a first diode D10, the anode of the first diode D10 is connected to the negative electrode of the absorption capacitor, and the cathode of the first diode D10 is connected to the outside.

[0010] Preferably, a switch is connected in parallel at both ends of each energy-consuming resistor, and the ends of the energy-consuming resistor are connected to the adjacent absorption capacitor by the switch.

[0011] Preferably, the absorption circuit includes a first absorption circuit connected in parallel at both ends of the upper bridge arm and a second absorption circuit connected in parallel at both ends of the lower bridge arm, the fourth switch Tq on the first absorption circuit is connected in the middle of each bridge arm of the three-phase inverter circuit, and the cathode of the first diode D10 on the first absorption circuit is connected to the positive terminal of the DC power supply;

[0012] Among them, a second diode D31 is arranged between the middle of the first bridge arm and the first absorption circuit, and the anode of the second diode D31 is connected to the middle of the first bridge arm; a third diode D32 is arranged between the middle of the second bridge arm and the first absorption circuit, and the anode of the third diode D32 is connected to the middle of the second bridge arm; a fourth diode D33 is arranged between the middle of the third bridge arm and the first absorption circuit, and the anode of the fourth diode D33 is connected to the middle of the third bridge arm.

[0013] Preferably, a first energy storage capacitor C1 is connected in parallel at both ends of the first absorption circuit, and a fourth switch Tq on the first absorption circuit is connected to the positive electrode of the first energy storage capacitor C1 through a fifth diode D4, wherein the cathode of the fifth diode D4 is connected to the positive electrode of the first energy storage capacitor C1;

[0014] The cathode of the first energy storage capacitor C1 is connected to the anode of the first diode D10 on the first absorption circuit through the sixth diode D2, wherein the anode of the sixth diode D2 is connected to the cathode of the first energy storage capacitor C1.

[0015] Preferably, the fourth switch Tq on the second absorption circuit is connected to the negative terminal of the DC power supply, and the cathode of the first diode D10 on the first absorption circuit is connected to the middle of each bridge arm of the three-phase inverter circuit;

[0016] Among them, a seventh diode D7 is arranged between the middle of the first bridge arm and the second absorption circuit, and the cathode of the seventh diode D7 is connected to the middle of the first bridge arm; an eighth diode D6 is arranged between the middle of the second bridge arm and the second absorption circuit, and the cathode of the eighth diode D6 is connected to the middle of the second bridge arm; a ninth diode D5 is arranged between the middle of the third bridge arm and the second absorption circuit, and the cathode of the ninth diode D5 is connected to the middle of the third bridge arm.

[0017] Preferably, a second energy storage capacitor C2 is connected in parallel at both ends of the second absorption circuit, and a fourth switch Tq on the second absorption circuit is connected to the positive electrode of the second energy storage capacitor C2 through a tenth diode D9, wherein the cathode of the tenth diode D9 is connected to the positive electrode of the second energy storage capacitor C2;

[0018] The cathode of the second energy storage capacitor C2 is connected to the anode of the first diode D10 on the second absorption circuit through the fifth switch T6.

[0019] Preferably, the positive electrode of the first energy storage capacitor C1 is connected to the negative electrode of the second energy storage capacitor C2 through the first switch T4, the negative electrode of the first energy storage capacitor C1 is connected to the negative terminal of the DC power supply through the sixth switch T7, and the positive electrode of the second energy storage capacitor C2 is connected to the positive terminal of the DC power supply through the seventh switch T5 and the eleventh diode D1 in sequence, wherein the anode of the eleventh diode D1 is connected to the seventh switch T5.

[0020] Preferably, a thirteenth diode D8 is provided at the negative terminal of the DC power supply, and the sixth switch T7 and the second absorption circuit are connected to the negative terminal of the DC power supply through the thirteenth diode D8.

[0021] A control method for a permanent magnet synchronous motor control system comprises the following steps:

[0022] Step 1: During the process of controlling the upper bridge arm to be turned on and the corresponding lower bridge arm to be turned off, calculate the time interval T1 between the lower bridge arm from the trigger disconnection moment to the corresponding stator winding current zero-crossing moment, and perform the following operations on the second absorption circuit: respectively close the switches between the head and tail of the energy-consuming resistor and the adjacent absorption capacitor, disconnect the switches at both ends of each of the energy-consuming resistors, close the fourth switch Tq and the fifth switch T6, and absorb the back electromotive force generated on the stator winding when the lower bridge arm is turned off through the second energy storage capacitor C2, each absorption capacitor and each energy-consuming resistor at the same time, and charge the second energy storage capacitor C2 and each absorption capacitor at the same time; after 0.5T1 time, disconnect the switch between the head and tail of the energy-consuming resistor and the adjacent absorption capacitor, close the switch at both ends of each of the energy-consuming resistors, and charge the second energy storage capacitor C2 after connecting each absorption capacitor in series; after 0.75T1 time, close the switch between the head and tail of the energy-consuming resistor and the adjacent absorption capacitor, disconnect the fifth switch T6, disconnect the switches at both ends of each of the energy-consuming resistors, and absorb the electric energy on the absorption capacitor through the energy-consuming resistor;

[0023] Step 2: During the process of controlling the upper bridge arm to be turned off and the corresponding lower bridge arm to be turned on, calculate the time interval T2 between the trigger disconnection moment of the upper bridge arm and the zero-crossing moment of the corresponding stator winding current, and perform the following operations on the first absorption circuit: respectively close the switches between the head and tail of the energy-consuming resistor and the adjacent absorption capacitor, disconnect the switches at both ends of each of the energy-consuming resistors, close the fourth switch Tq, and absorb the back electromotive force generated on the stator winding when the upper bridge arm is turned off by the first energy storage capacitor C1, each absorption capacitor and each energy-consuming resistor at the same time, and charge the first energy storage capacitor C1 and each absorption capacitor at the same time; after 0.5T2 time, disconnect the switch between the head and tail of the energy-consuming resistor and the adjacent absorption capacitor, close the switch at both ends of each of the energy-consuming resistors, and charge the first energy storage capacitor C1 after connecting each absorption capacitor in series; after 0.75T1 time, close the switch between the head and tail of the energy-consuming resistor and the adjacent absorption capacitor, disconnect the switch at both ends of each of the energy-consuming resistors, and absorb the electric energy on the absorption capacitor through the energy-consuming resistor;

[0024] Step 3: When the motor starts, close the first switch T4, the sixth switch T7 and the seventh switch T5, connect the first energy storage capacitor C1 and the second energy storage capacitor C2 in series and input them to the positive terminal of the DC power supply to increase the starting excitation voltage of the motor.

[0025] The present invention has at least the following beneficial effects:

[0026] 1. Use an absorption circuit in each of the upper bridge arm and the lower bridge arm to absorb the back electromotive force generated on the shut-off phase, reducing the interference of the back electromotive force on the precise control of the motor;

[0027] 2. Absorb part of the back electromotive force energy and store it in the energy storage capacitor. When the motor starts, it provides a high starting voltage to the motor, realizes the rapid start of the motor, and further improves the control accuracy of the motor.

[0028] Other advantages, objectives and features of the present invention will be embodied in part through the following description, and in part will be understood by those skilled in the art through study and practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 It is a schematic diagram of the overall structure of the system of the present invention;

[0030] Figure 2 This is a schematic diagram of the absorption circuit. DETAILED DESCRIPTION

[0031] The present invention is further described in detail below in conjunction with the accompanying drawings so that those skilled in the art can implement the invention with reference to the description.

[0032] It should be understood that terms such as “having”, “including” and “comprising” used herein do not specify the existence or addition of one or more other elements or combinations thereof.

[0033] like Figure 1-2 As shown, the present invention provides a high-precision controlled permanent magnet synchronous motor control system, wherein the three-phase inverter circuit is composed of three pairs of upper and lower bridge arms, the input end of the three-phase inverter circuit is connected to a DC power supply, the output end of the three-phase inverter circuit is connected to the three-phase stator winding of the permanent magnet synchronous motor, the middle output end of the first bridge arm is connected to the A-phase stator winding, the middle output end of the second bridge arm is correspondingly connected to the B-phase stator winding, and the middle output end of the third bridge arm is correspondingly connected to the C-phase stator winding.

[0034] The two ends of the upper and lower bridge arms of the three-phase inverter circuit are each connected in parallel with an absorption circuit. Figure 1 As shown, the first absorption circuit 1 is set at both ends of the three upper bridge arms, and the second absorption circuit 2 is set at both ends of the three lower bridge arms. The structures of the absorption circuits are the same, such as Figure 2 shown.

[0035] Specifically, the absorption circuit includes a plurality of absorption capacitors arranged in parallel, and an energy-dissipating resistor is arranged in parallel between every two of the absorption capacitors. In the present embodiment, the absorption circuit includes three absorption capacitors C3, C4, and C5 arranged in parallel, an energy-dissipating resistor R1 is connected in parallel between the absorption capacitor C3 and the absorption capacitor C4, and an energy-dissipating resistor R2 is connected in parallel between the absorption capacitor C4 and the absorption capacitor C5. The positive electrode of each of the absorption capacitors is connected to the outside through a fourth switch Tq, and the negative electrode of each of the absorption capacitors is connected to a first diode D10. Specifically, the anode of the first diode D10 is connected to the negative electrode of the absorption capacitor, and the cathode of the first diode D10 is connected to the outside.

[0036] A switch Tc is connected in parallel at both ends of the energy dissipation resistor R1, a switch Td is connected in parallel at both ends of the energy dissipation resistor R2, a switch T8 is arranged on the line between the tail end of the energy dissipation resistor R1 and the negative electrode of the absorption capacitor C3, a switch T10 is arranged on the line between the head end of the energy dissipation resistor R1 and the positive electrode of the absorption capacitor C4, a switch T9 is arranged on the line between the tail end of the energy dissipation resistor R2 and the negative electrode of the absorption capacitor C4, and a switch T13 is arranged on the line between the head end of the energy dissipation resistor R2 and the positive electrode of the absorption capacitor C5. In the early stage of back electromotive force generation, when switches T8, T9, T10, and T13 are closed, and switches Tc and Td are opened, the absorption circuit becomes a parallel structure of absorption capacitor and energy dissipation resistor, which is used to absorb the back electromotive force of the winding in the early stage of back electromotive force generation, the absorption capacitor is charged, and the energy dissipation resistor directly consumes, thereby improving the instantaneous absorption capacity of back electromotive force and reducing the impact of back electromotive force on the motor.

[0037] When switches T8, T9, T10, and T13 are disconnected and switches Tc and Td are closed, the absorption circuit becomes a circuit structure in which the absorption capacitors are connected in series and the energy-consuming resistors are removed. After the absorption capacitors are connected in series, the output voltage of the absorption capacitor is increased to charge the energy storage capacitor.

[0038] When the absorption capacitors in series finish charging the energy storage capacitors, switches T8, T9, T10, and T13 are closed, and switches Tc and Td are opened. The absorption circuit becomes a parallel structure of absorption capacitors and energy-consuming resistors again. The energy-consuming resistors absorb the remaining electric energy in the absorption capacitors until it is consumed. Each absorption capacitor waits for the next back electromotive force absorption process. The absorption capacitors that have been consumed by the energy-consuming resistors have improved their ability to absorb the back electromotive force.

[0039] like Figure 1 As shown, the fourth switch Tq on the first absorption circuit 1 is connected in the middle of each bridge arm of the three-phase inverter circuit, and the cathode of the first diode D10 on the first absorption circuit is connected to the positive terminal of the DC power supply. When any one of the upper bridge arms is turned off, a back electromotive force will be generated at both ends of the upper bridge arm. At this time, the fourth switch Tq is controlled to be turned on, and the back electromotive force is introduced into the first absorption circuit 1 for absorption.

[0040] Among them, a second diode D31 is arranged between the middle of the first bridge arm and the first absorption circuit, and the anode of the second diode D31 is connected to the middle of the first bridge arm; a third diode D32 is arranged between the middle of the second bridge arm and the first absorption circuit, and the anode of the third diode D32 is connected to the middle of the second bridge arm; a fourth diode D33 is arranged between the middle of the third bridge arm and the first absorption circuit, and the anode of the fourth diode D33 is connected to the middle of the third bridge arm.

[0041] The second diode D31 , the third diode D32 and the fourth diode D33 are provided to prevent the energy storage in the first absorption circuit 1 from flowing into the middle of the bridge arm and interfering with the control of the motor.

[0042] A first energy storage capacitor C1 is connected in parallel at both ends of the first absorption circuit 1. The function of the energy storage capacitor is to store the back electromotive force energy therein, which is used to increase the excitation voltage when the motor starts, so that the motor starts quickly. The fourth switch Tq on the first absorption circuit 1 is connected to the positive electrode of the first energy storage capacitor C1 through the fifth diode D4, wherein the cathode of the fifth diode D4 is connected to the positive electrode of the first energy storage capacitor C1; the negative electrode of the first energy storage capacitor C1 is connected to the anode of the first diode D10 on the first absorption circuit 1 through the sixth diode D2, wherein the anode of the sixth diode D2 is connected to the negative electrode of the first energy storage capacitor C1, so that the first energy storage capacitor C1 is connected in parallel at both ends of the first absorption circuit 1.

[0043] At the initial stage of back electromotive force generation, when switches T8, T9, T10, and T13 are closed, and switches Tc and Td are disconnected, the absorption circuit becomes a parallel structure of absorption capacitor and energy-consuming resistor. Since the first energy storage capacitor C1 is connected in parallel at both ends of the first absorption circuit 1, the first absorption circuit 1 and the first energy storage capacitor C1 absorb the back electromotive force of the winding at the same time, reducing the impact interference of the back electromotive force on the inverter bridge. As the charging process of the first energy storage capacitor C1 continues, the voltage at both ends increases. When the voltage at both ends of the first energy storage capacitor C1 is greater than the maximum voltage of the back electromotive force, the first energy storage capacitor C1 cannot directly absorb the back electromotive force. The setting of the fifth diode D4 makes it impossible for the energy stored in the first energy storage capacitor C1 to be fed back to the first absorption circuit 1 and the three-phase inverter circuit.

[0044] When switches T8, T9, T10, and T13 are disconnected, and switches Tc and Td are closed, the absorption circuit becomes a circuit structure in which each absorption capacitor is connected in series and the energy-consuming resistor is removed. After each absorption capacitor is connected in series, the output voltage of the absorption capacitor is increased to charge the first energy storage capacitor C1. As long as the motor is kept running for a period of time, the terminal voltage of the first energy storage capacitor C1 will eventually be no less than the maximum back electromotive voltage. Finally, when the motor starts, the first energy storage capacitor C1 is fed back to the DC power supply input terminal to instantly increase the motor starting voltage and achieve rapid motor starting. As a result, the absorption circuit and the energy storage capacitor participate in the process of absorbing the back electromotive force, reduce the impact interference of the back electromotive force on the inverter circuit, and store part of the back electromotive force energy, which is used to instantly increase the motor starting voltage and achieve rapid motor starting.

[0045] The working process of the second absorption circuit 2 is similar to that of the first absorption circuit 1, and the connection method of the second absorption circuit 2 is slightly different from that of the first absorption circuit 1. Specifically, the fourth switch Tq on the second absorption circuit 2 is connected to the negative end of the DC power supply, and the cathode of the first diode D10 on the first absorption circuit is connected to the middle of each bridge arm of the three-phase inverter circuit; when any one of the lower bridge arms is turned off, a back electromotive force will be generated at both ends of the lower bridge arm. At this time, the fourth switch Tq is controlled to be turned on, and the back electromotive force is introduced into the second absorption circuit 2 for absorption.

[0046] Among them, a seventh diode D7 is arranged between the middle of the first bridge arm and the second absorption circuit, and the cathode of the seventh diode D7 is connected to the middle of the first bridge arm; an eighth diode D6 is arranged between the middle of the second bridge arm and the second absorption circuit, and the cathode of the eighth diode D6 is connected to the middle of the second bridge arm; a ninth diode D5 is arranged between the middle of the third bridge arm and the second absorption circuit, and the cathode of the ninth diode D5 is connected to the middle of the third bridge arm. The seventh diode D7, the eighth diode D6 and the ninth diode D5 are arranged to prevent the electric energy in the middle of the bridge arm from flowing into the second absorption circuit 2 and causing interference.

[0047] A second energy storage capacitor C2 is connected in parallel at both ends of the second absorption circuit 2, and a fourth switch Tq on the second absorption circuit is connected to the positive electrode of the second energy storage capacitor C2 through a tenth diode D9, wherein the cathode of the tenth diode D9 is connected to the positive electrode of the second energy storage capacitor C2; and a negative electrode of the second energy storage capacitor C2 is connected to the anode of the first diode D10 on the second absorption circuit through a fifth switch T6. Thus, the second energy storage capacitor C2 is connected in parallel to both ends of the second absorption circuit 2.

[0048] At the initial stage of back electromotive force generation, when switches T8, T9, T10, and T13 are closed, and switches Tc and Td are disconnected, the absorption circuit becomes a parallel structure of absorption capacitor and energy-consuming resistor. Since the second energy storage capacitor C2 is connected in parallel at both ends of the second absorption circuit 2, the second absorption circuit 2 and the second energy storage capacitor C2 absorb the back electromotive force of the winding at the same time, reducing the impact interference of the back electromotive force on the inverter bridge. As the charging process of the second energy storage capacitor C2 continues, the voltage at both ends increases. When the voltage at both ends of the second energy storage capacitor C2 is greater than the maximum voltage of the back electromotive force, the second energy storage capacitor C2 cannot directly absorb the back electromotive force. The setting of the tenth diode D9 makes it impossible for the energy stored in the second energy storage capacitor C2 to be fed back to the second absorption circuit 1 and the negative terminal of the DC power supply.

[0049] When switches T8, T9, T10, and T13 are disconnected, and switches Tc and Td are closed, the absorption circuit becomes a circuit structure in which each absorption capacitor is connected in series and the energy-consuming resistor is removed. After each absorption capacitor is connected in series, the output voltage of the absorption capacitor is increased to charge the second energy storage capacitor C2. As long as the motor is kept running for a period of time, the terminal voltage of the second energy storage capacitor C2 is eventually made not less than the maximum back electromotive voltage. Finally, when the motor starts, the second energy storage capacitor C2 is fed back to the DC power supply input terminal to instantly increase the motor starting voltage and achieve rapid motor starting. As a result, the absorption circuit and the energy storage capacitor participate in the process of absorbing the back electromotive force, reduce the impact interference of the back electromotive force on the inverter circuit, and store part of the back electromotive force energy, which is used to instantly increase the motor starting voltage and achieve rapid motor starting.

[0050] Further, the positive electrode of the first energy storage capacitor C1 is connected to the negative electrode of the second energy storage capacitor C2 through the first switch T4, the negative electrode of the first energy storage capacitor C1 is connected to the negative terminal of the DC power supply through the sixth switch T7, and the positive electrode of the second energy storage capacitor C2 is connected to the positive terminal of the DC power supply through the seventh switch T5 and the eleventh diode D1 in sequence, wherein the anode of the eleventh diode D1 is connected to the seventh switch T5.

[0051] The construction of this loop allows the first energy storage capacitor C1 and the second energy storage capacitor C2 to be connected in series through the first switch T4, and then the series positive terminal is connected to the positive terminal of the DC power supply through the seventh switch T5, and the series negative terminal is connected to the negative terminal of the DC power supply through the sixth switch T7. After the first energy storage capacitor C1 and the second energy storage capacitor C2 are connected in series, they are fed back to the DC power supply end. After the first energy storage capacitor C1 and the second energy storage capacitor C2 are connected in series, the output voltage is further improved, which effectively improves the instantaneous starting voltage of the motor and realizes rapid starting of the motor.

[0052] In the above technical solution, a thirteenth diode D8 is set at the negative end of the DC power supply, and the sixth switch T7 and the second absorption circuit are connected to the negative end of the DC power supply through the thirteenth diode D8 to prevent the electric energy on the bridge arm or the absorption circuit from being directly short-circuited to the negative end of the DC power supply.

[0053] A control method for a permanent magnet synchronous motor control system comprises the following steps:

[0054] Step 1: During the process of controlling any upper bridge arm to be turned on and the corresponding lower bridge arm to be turned off, calculate the time interval T1 between the lower bridge arm from the trigger disconnection moment to the corresponding stator winding current zero-crossing moment, and perform the following operations on the second absorption circuit: when switches T8, T9, T10, and T13 are closed and switches Tc and Td are disconnected, the absorption circuit becomes a parallel structure of an absorption capacitor and an energy-consuming resistor. Since the second energy storage capacitor C2 is connected in parallel to both ends of the second absorption circuit 2, the second absorption circuit 2 and the second energy storage capacitor C2 simultaneously absorb the back electromotive force of the winding, thereby reducing the impact interference of the back electromotive force on the inverter bridge. In this process, the second energy storage capacitor C2 and each absorption capacitor are charged simultaneously to quickly absorb the back electromotive force.

[0055] When the back electromotive force peak has passed, that is, after 0.5T1 time, at this time, the switches T8, T9, T10, and T13 are disconnected, and the switches Tc and Td are closed, and the absorption circuit becomes a circuit structure in which each absorption capacitor is connected in series and the energy-consuming resistor is removed. After each absorption capacitor is connected in series, the output voltage of the absorption capacitor is increased to charge the second energy storage capacitor C2. As long as the motor is kept running for a period of time, the terminal voltage of the second energy storage capacitor C2 is eventually made not less than the maximum back electromotive force voltage. Finally, when the motor starts, the second energy storage capacitor C2 is fed back to the DC power supply input terminal to instantly increase the motor starting voltage and realize the rapid start of the motor. Therefore, the absorption circuit and the energy storage capacitor participate in the process of absorbing the back electromotive force, reduce the impact interference of the back electromotive force on the inverter circuit, and store part of the back electromotive force energy at the same time, which is used to instantly increase the motor starting voltage and realize the rapid start of the motor.

[0056] Finally, after 0.75T1 time, the switches T8, T9, T10, and T13 are closed, the fifth switch T6 is opened, and the switches Tc and Td are opened, and the energy on the absorption capacitor is absorbed by the energy dissipation resistors R1 and R2 until it is consumed, waiting for the next back electromotive force absorption process.

[0057] Step 2, during the process of controlling any upper bridge arm to be turned off and the corresponding lower bridge arm to be turned on, the operation process is similar to step 1, and the time interval T2 between the trigger disconnection moment of the upper bridge arm and the zero-crossing moment of the corresponding stator winding current is calculated, and the following operations are performed on the first absorption circuit: respectively close the switches between the head and tail of the energy-consuming resistor and the adjacent absorption capacitor, disconnect the switches at both ends of each of the energy-consuming resistors, close the fourth switch Tq, and absorb the back electromotive force generated on the stator winding when the upper bridge arm is turned off through the first energy storage capacitor C1, each absorption capacitor and each energy-consuming resistor at the same time, and charge the first energy storage capacitor C1 and each absorption capacitor at the same time; after 0.5T2 time, disconnect the switch between the head and tail of the energy-consuming resistor and the adjacent absorption capacitor, close the switch at both ends of each of the energy-consuming resistors, and charge the first energy storage capacitor C1 after connecting each absorption capacitor in series; after 0.75T1 time, close the switch between the head and tail of the energy-consuming resistor and the adjacent absorption capacitor, disconnect the switch at both ends of each of the energy-consuming resistors, and absorb the electrical energy on the absorption capacitor through the energy-consuming resistor.

[0058] Step 3: When the motor starts, close the first switch T4, the sixth switch T7 and the seventh switch T5, connect the first energy storage capacitor C1 and the second energy storage capacitor C2 in series and input them to the positive terminal of the DC power supply to increase the starting excitation voltage of the motor and achieve rapid starting of the motor.

[0059] As described above, the present invention uses an absorption circuit in the upper bridge arm and the lower bridge arm respectively to absorb the back electromotive force generated on the turned-off phase, thereby reducing the interference of the back electromotive force on the precise control of the motor; at the same time, part of the back electromotive force energy is absorbed and stored in the energy storage capacitor, which is used to provide a high starting voltage to the motor when the motor is started, thereby realizing rapid starting of the motor and further improving the control accuracy of the motor.

[0060] Although the embodiments of the present invention have been disclosed as above, they are not limited to the applications listed in the specification and the implementation modes, and they can be fully applied to various fields suitable for the present invention. For those familiar with the art, additional modifications can be easily implemented. Therefore, without departing from the general concept defined by the claims and the scope of equivalents, the present invention is not limited to the specific details and the illustrations shown and described herein.

Claims

1. A high-precision permanent magnet synchronous motor control system, characterized in that: include: A three-phase inverter circuit, an input end of which is connected to a DC power supply, and an output end of the three-phase inverter circuit is connected to a three-phase stator winding of a permanent magnet synchronous motor; An absorption circuit, wherein the two ends of the upper and lower bridge arms of the three-phase inverter circuit are each connected in parallel with the absorption circuit; An energy storage capacitor is connected in parallel at both ends of the absorption circuit, the upper and lower energy storage capacitors are connected in series through a first switch T4, the positive electrodes of the two energy storage capacitors arranged in series are connected to the positive terminal of the DC power supply through a second switch T5, and the negative electrodes of the two energy storage capacitors arranged in series are connected to the negative terminal of the DC power supply through a third switch T7; The absorption circuit includes a plurality of absorption capacitors arranged in parallel, an energy-consuming resistor is arranged in parallel between every two absorption capacitors, the positive electrode of the absorption capacitor is connected to the outside through a fourth switch Tq, the negative electrode of the absorption capacitor is connected to a first diode D10, the anode of the first diode D10 is connected to the negative electrode of the absorption capacitor, and the cathode of the first diode D10 is connected to the outside; a switch is connected in parallel at both ends of each energy-consuming resistor, and the head and tail of the energy-consuming resistor are connected to the adjacent absorption capacitor by a switch; The absorption circuit includes a first absorption circuit connected in parallel at both ends of the upper bridge arm and a second absorption circuit connected in parallel at both ends of the lower bridge arm. The fourth switch Tq on the first absorption circuit is connected to the middle of each bridge arm of the three-phase inverter circuit. The cathode of the first diode D10 on the first absorption circuit is connected to the positive end of the DC power supply. A second diode D31 is arranged between the middle of the first bridge arm and the first absorption circuit, and the anode of the second diode D31 is connected to the middle of the first bridge arm. A third diode D32 is arranged between the middle of the second bridge arm and the first absorption circuit, and the anode of the third diode D32 is connected to the middle of the second bridge arm. A fourth diode D33 is arranged between the middle of the third bridge arm and the first absorption circuit, and the anode of the fourth diode D33 is connected to the middle of the third bridge arm.

2. The high-precision controlled permanent magnet synchronous motor control system according to claim 1, characterized in that: A first energy storage capacitor C1 is connected in parallel at both ends of the first absorption circuit, and a fourth switch Tq on the first absorption circuit is connected to the positive electrode of the first energy storage capacitor C1 through a fifth diode D4, wherein the cathode of the fifth diode D4 is connected to the positive electrode of the first energy storage capacitor C1; The cathode of the first energy storage capacitor C1 is connected to the anode of the first diode D10 on the first absorption circuit through the sixth diode D2, wherein the anode of the sixth diode D2 is connected to the cathode of the first energy storage capacitor C1.

3. The high-precision controlled permanent magnet synchronous motor control system according to claim 2, characterized in that: The fourth switch Tq on the second absorption circuit is connected to the negative terminal of the DC power supply, and the cathode of the first diode D10 on the second absorption circuit is connected to the middle of each bridge arm of the three-phase inverter circuit; Among them, a seventh diode D7 is arranged between the middle of the first bridge arm and the second absorption circuit, and the cathode of the seventh diode D7 is connected to the middle of the first bridge arm; an eighth diode D6 is arranged between the middle of the second bridge arm and the second absorption circuit, and the cathode of the eighth diode D6 is connected to the middle of the second bridge arm; a ninth diode D5 is arranged between the middle of the third bridge arm and the second absorption circuit, and the cathode of the ninth diode D5 is connected to the middle of the third bridge arm.

4. The high-precision controlled permanent magnet synchronous motor control system according to claim 3, characterized in that: A second energy storage capacitor C2 is connected in parallel at both ends of the second absorption circuit, and a fourth switch Tq on the second absorption circuit is connected to the positive electrode of the second energy storage capacitor C2 through a tenth diode D9, wherein the cathode of the tenth diode D9 is connected to the positive electrode of the second energy storage capacitor C2; The cathode of the second energy storage capacitor C2 is connected to the anode of the first diode D10 on the second absorption circuit through the fifth switch T6.

5. The high-precision controlled permanent magnet synchronous motor control system according to claim 4, characterized in that: The positive electrode of the first energy storage capacitor C1 is connected to the negative electrode of the second energy storage capacitor C2 through the first switch T4, the negative electrode of the first energy storage capacitor C1 is connected to the negative terminal of the DC power supply through the sixth switch T7, and the positive electrode of the second energy storage capacitor C2 is connected to the positive terminal of the DC power supply through the seventh switch T5 and the eleventh diode D1 in sequence, wherein the anode of the eleventh diode D1 is connected to the seventh switch T5.

6. The high-precision controlled permanent magnet synchronous motor control system according to claim 5, characterized in that: A thirteenth diode D8 is provided at the negative terminal of the DC power supply, and the sixth switch T7 and the second absorption circuit are connected to the negative terminal of the DC power supply through the thirteenth diode D8.

7. The control method of the permanent magnet synchronous motor control system with high precision control as claimed in claim 6, characterized in that: The following steps are involved: Step 1: During the process of controlling the upper bridge arm to be turned on and the corresponding lower bridge arm to be turned off, calculate the time interval T1 between the lower bridge arm from the trigger disconnection moment to the corresponding stator winding current zero-crossing moment, and perform the following operations on the second absorption circuit: respectively close the switches between the head and tail of the energy-consuming resistor and the adjacent absorption capacitor, disconnect the switches at both ends of each of the energy-consuming resistors, close the fourth switch Tq and the fifth switch T6, and absorb the back electromotive force generated on the stator winding when the lower bridge arm is turned off through the second energy storage capacitor C2, each absorption capacitor and each energy-consuming resistor at the same time, and charge the second energy storage capacitor C2 and each absorption capacitor at the same time; after 0.5T1 time, disconnect the switch between the head and tail of the energy-consuming resistor and the adjacent absorption capacitor, close the switch at both ends of each of the energy-consuming resistors, and charge the second energy storage capacitor C2 after connecting each absorption capacitor in series; after 0.75T1 time, close the switch between the head and tail of the energy-consuming resistor and the adjacent absorption capacitor, disconnect the fifth switch T6, disconnect the switches at both ends of each of the energy-consuming resistors, and absorb the electric energy on the absorption capacitor through the energy-consuming resistor; Step 2: During the process of controlling the upper bridge arm to be turned off and the corresponding lower bridge arm to be turned on, the time interval T2 between the trigger disconnection moment of the upper bridge arm and the zero-crossing moment of the corresponding stator winding current is calculated, and the following operations are performed on the first absorption circuit: the switches between the ends of the energy-consuming resistor and the adjacent absorption capacitors are closed respectively, the switches at both ends of each energy-consuming resistor are opened, and the fourth switch Tq is closed, and the back electromotive force generated on the stator winding when the upper bridge arm is turned off is absorbed simultaneously by the first energy storage capacitor C1, each absorption capacitor and each energy-consuming resistor, and the first energy storage capacitor C1 and each absorption capacitor are charged simultaneously; After 0.5T2 time, the switches between the ends of the energy-consuming resistors and the adjacent absorption capacitors are disconnected, and the switches at both ends of each energy-consuming resistor are closed, and the absorption capacitors are connected in series to charge the first energy storage capacitor C1; After 0.75T2 time, the switches between the ends of the energy dissipation resistors and the adjacent absorption capacitors are closed, and the switches at both ends of each energy dissipation resistor are opened, so that the energy on the absorption capacitor is absorbed by the energy dissipation resistors; Step 3: When the motor starts, close the first switch T4, the sixth switch T7 and the seventh switch T5, connect the first energy storage capacitor C1 and the second energy storage capacitor C2 in series and input them to the positive terminal of the DC power supply to increase the starting excitation voltage of the motor.

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