Switched reluctance motor control system and control method based on four-level power circuit

Abstract

The present invention belongs to the technical field of motor drive control, and proposes a switch reluctance motor control system and control method based on a four-level power circuit, including a four-level power circuit, a switch reluctance motor, a controller, a voltage sensor, a current sensor, a position sensor, and a capacitor protection circuit. Based on the high-voltage rapid excitation and high-voltage rapid demagnetization of the four-level power circuit and the function that the operation mode can be independently controlled when each phase of the motor is overlapped and turned on, the present invention solves the problem that the excitation current is difficult to establish and the demagnetization current has a long tail when the switch reluctance motor is running at high speed through the optimization of control strategy and control parameters, improves the operating efficiency of the switch reluctance motor drive system, and broadens the speed regulation range of the switch reluctance motor.

Description

Technical Field

[0001] The present invention belongs to the technical field of motor drive control, and in particular relates to a switched reluctance motor control system and a control method based on a four-level power circuit. Background Art

[0002] Switched reluctance motors are widely used in various industrial applications due to their simple structure, high reliability, low cost, good speed regulation performance, and no need for rare earth permanent magnets. However, they also have problems such as low torque density, low efficiency, and large torque pulsation. In terms of reducing torque pulsation, many studies have been conducted and good results have been achieved. In terms of improving torque density and operating efficiency and expanding the speed regulation range, in addition to the optimized design of switched reluctance motors, many studies have also been conducted on the optimized control of switched reluctance motors. The turn-on angle and turn-off angle are important control parameters of switched reluctance motors. Therefore, the output performance of the switched reluctance motor drive system is improved by optimizing the excitation control angle.

[0003] When the switched reluctance motor runs at high speed, the back electromotive force of the motor increases and the excitation and demagnetization time per cycle is shortened, making it difficult for the phase current to reach the expected value during normal voltage excitation. In the switched reluctance motor control system based on the traditional asymmetric half-bridge power circuit, normal voltage excitation and normal voltage demagnetization cannot meet the requirements of rapid establishment and rapid decrease of phase current, affecting the output performance of the motor. In addition, when the switched reluctance motor runs at high speed, adjacent phases are often in an overlapping conduction operation state, and the independence of the operation mode between phases is very important for formulating more flexible control strategies to further optimize the output performance of the switched reluctance motor.

[0004] In summary, in order to improve the output performance of the motor and improve the operating efficiency of the motor, it is an urgent problem to propose a switched reluctance motor control system with high-voltage excitation and high-voltage demagnetization capabilities that can overcome the limitations of the bus voltage in the traditional system and whose operating modes of adjacent phases can be independently controlled during overlapping conduction operation. Summary of the invention

[0005] In view of the deficiencies of the prior art, the present invention proposes a switch reluctance motor control system and control method based on a four-level power circuit. Based on the high-voltage rapid excitation and high-voltage rapid demagnetization of the four-level power circuit and the function that the operation mode can be independently controlled when the adjacent phases of the motor are overlapped and turned on, the present invention solves the problem that the excitation current is difficult to establish when the switch reluctance motor is running at high speed and the demagnetization current easily extends to the inductance drop area through the optimization of the control strategy and control parameters, improves the operating efficiency of the switch reluctance motor drive system, and broadens the speed regulation range of the switch reluctance motor.

[0006] The technical solution of the present invention is: a switched reluctance motor control system and a control method based on a four-level power circuit, the system comprising a four-level power circuit, a switched reluctance motor, a controller, a voltage sensor, a current sensor, a position sensor and a capacitor protection circuit.

[0007] Among them, the four-level power circuit includes a DC power supply, a voltage-stabilizing capacitor C1, a boost capacitor C2 and a bridge arm circuit composed of a switch tube and a diode. The number of bridge arm circuits is equal to the number of phases of the motor, and each bridge arm is connected to a phase motor winding.

[0008] The voltage-stabilizing capacitor C1 is connected in parallel with the DC power supply, and the negative electrode of the boosting capacitor C2 is connected in series with the positive electrode of the voltage-stabilizing capacitor C1.

[0009] The bridge arm circuit includes switch tubes Q1, Q2, Q3, and diodes D1, D2, D3; the emitter of the switch tube Q3 in the bridge arm circuit is connected to the negative electrode of the DC power supply, and the collector of the switch tube Q1 is connected to the positive electrode of the boost capacitor C2.

[0010] The upper end of the switched reluctance motor winding is connected to the emitter of the switch tube Q2, and the lower end of the motor winding is connected to the collector of the switch tube Q3.

[0011] The voltage sensor is placed at both ends of the boost capacitor C2 of the four-level power circuit, the current sensor is placed on each phase bridge arm of the four-level power circuit and connected to each phase winding of the motor, and the position sensor is used to collect the rotor position feedback value of the switched reluctance motor.

[0012] The capacitor protection circuit receives the voltage value of the boost capacitor C2 collected by the voltage sensor, compares it with the capacitor voltage value preset by the hysteresis comparator, obtains a logic signal indicating whether the capacitor needs to be discharged, and outputs it to the IGBT drive circuit. In addition, the capacitor protection circuit allows the controller to perform active protection actions.

[0013] The controller is used to receive the boost capacitor voltage value of the four-level power circuit collected by the voltage sensor, the current value of each phase collected by the current sensor, and the rotor position feedback value of the switched reluctance motor collected by the position sensor, and the output end of the controller is connected to the drive circuit of the bridge arm switch tube of each phase of the four-level power circuit.

[0014] The controller of the control system executes the MTPA control strategy to achieve the maximum torque-ampere ratio operation of the switched reluctance motor drive system through optimization control. The control method includes the following steps:

[0015] a. Based on the speed deviation between the real-time speed ω and the given speed ω*, the speed controller calculates the reference torque T ref ;

[0016] b. Based on the reference torque T ref and real-time speed ω, and by checking the MTPA control parameter table, the control parameters of the optimized switched reluctance motor are obtained, including the opening angle θ at which the motor phase winding starts to be excited on , the turn-off angle θ at which demagnetization begins off , reference current I ref and the opening angle of high voltage excitation

[0017] c. Based on the actual voltage of the boost capacitor and a given reference voltage The high voltage excitation cut-off angle of the switched reluctance motor is obtained through the closed-loop control of the bus voltage.

[0018] d. Based on the reference current I ref The winding current feedback value and the rotor position feedback value of the switched reluctance motor are used. Current chopping control is used at low speed, and angle position control is used at high speed.

[0019] The switch reluctance motor control system and control method based on the four-level power circuit adopts the MTPA control strategy based on the four-level power circuit, makes full use of high-voltage excitation and high-voltage demagnetization, and realizes maximum torque-ampere ratio optimization operation through optimization control.

[0020] The stabilization of the high-voltage bus voltage of the control system is achieved by bus voltage closed-loop control based on a four-level power circuit.

[0021] The bus voltage closed-loop control collects the output voltage of the boost capacitor at both ends. Get the preset capacitor voltage The deviation between them is then calculated by the voltage regulator to obtain the high-voltage excitation conduction width of the MTPA control strategy. That is, by controlling the time of high-voltage excitation, the discharge amount of the boost capacitor is controlled, and a balance between demagnetization feedback and excitation discharge is achieved during the charge and discharge process of the boost capacitor to achieve a stable bus voltage.

[0022] The bus voltage closed-loop control strategy can not only achieve the charge and discharge balance of the capacitor voltage and achieve bus voltage stability through automatic control, but also can autonomously adjust the boost capacitor voltage and achieve variable voltage control.

[0023] The switch reluctance motor control system and control method based on the four-level power circuit, wherein the capacitor protection circuit is composed of a hysteresis comparator, an AND logic gate, an IGBT driver, an IGBT switch tube Q S and the discharge resistor R S constitute.

[0024] The hysteresis comparator adjusts the upper and lower limits of the given capacitor voltage value through a potentiometer; the capacitor protection circuit receives the voltage value of the boost capacitor C2 collected by the voltage sensor, and when the voltage value of the boost capacitor C2 exceeds the set upper limit, the IGBT switch tube Q is driven. S Turn on, at this time, the boost capacitor C2 is discharged through the resistor R S Discharge; when discharged to the set lower limit, drive the IGBT switch tube Q S Shut down.

[0025] The capacitor protection circuit allows the controller to actively perform a discharge action. When the capacitor charge amount is greater than the discharge amount, the controller executes a protection action and performs active discharge.

[0026] The switch reluctance motor control system and control method based on the four-level power circuit, the control parameter table of the MTPA control strategy includes the opening angle θ at which the excitation starts on , the turn-off angle θ at which demagnetization begins off , reference current I ref and the opening angle of high voltage excitation The control parameter table is characterized by high-voltage excitation and high-voltage demagnetization based on a four-level power circuit, which is obtained by traversal optimization. The optimization steps include:

[0027] a. Place the high voltage excitation range in the area with smaller inductance, and through angle optimization, traverse to find the maximum torque-ampere ratio at each torque-speed point. To achieve efficient and rapid excitation;

[0028] b. Based on optimization and the automatic control of the bus voltage closed loop, and θ for each torque-speed operating point in the switched reluctance motor drive system based on the four-level power circuit on ,θ off and I ref Traverse and compare the performance indicators under each set of control parameter combinations to find the control parameter combination that makes the motor most efficient.

[0029] Compared with the prior art, the present invention has the following beneficial effects:

[0030] 1. The present invention provides a switched reluctance motor control system and a control method based on a four-level power circuit. By optimizing the control strategy and control parameters and utilizing the high-voltage excitation and high-voltage demagnetization capabilities of the four-level power circuit, the present invention solves the problems of the difficulty in establishing the excitation current and the long tail of the demagnetization current in the traditional switched reluctance motor drive system during high-speed operation, improves the operating efficiency of the switched reluctance motor drive system, and broadens the speed regulation range of the switched reluctance motor.

[0031] 2. The present invention provides a switched reluctance motor control system and control method based on a four-level power circuit. The stabilization of the bus voltage and the automatic control of the high-voltage excitation conduction width are achieved through closed-loop control of the boost capacitor voltage, thereby achieving stable and reliable operation of the system. At the same time, the boost capacitor voltage value is allowed to be actively adjusted, thereby increasing the control flexibility of the system. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 is a schematic diagram of the structure of a four-level power circuit adopted by the present invention;

[0033] Figure 2 It is a schematic diagram of a control block diagram of the control system proposed by the present invention;

[0034] Figure 3 It is a schematic diagram of a closed-loop control block diagram of the boost capacitor voltage proposed by the present invention;

[0035] Figure 4 Schematic diagram of the capacitor protection circuit proposed by the present invention. DETAILED DESCRIPTION

[0036] The present invention provides a switched reluctance motor control system and a control method based on a four-level power circuit, and the present invention is further described below in conjunction with the accompanying drawings.

[0037] like Figure 1 As shown, the present invention adopts a four-level power circuit, including a DC power supply, a voltage-stabilizing capacitor C1, a voltage-boosting capacitor C2, and a bridge arm circuit composed of a switch tube and a diode. The number of bridge arm circuits is equal to the number of phases of the motor, and each bridge arm is connected to a phase of the motor winding. This implementation case takes a three-phase switched reluctance motor as an example. The voltage-stabilizing capacitor C1 is connected in parallel with the DC power supply, and the negative electrode of the boost capacitor C2 is connected in series with the positive electrode of the voltage-stabilizing capacitor C1. Since the bridge arm circuit parts of each phase are connected in the same way, phase A is taken as an example for explanation. The bridge arm circuit of phase A includes a switch tube Q A1 , Q A2 , Q A3 , and diode D A1 , D A2 , D A3 .

[0038] The switch tube Q A1 The collector of is connected to the positive electrode of the boost capacitor C2, and the switch tube Q A1 The emitter of the switch tube Q A2 The collector of the switch tube Q A2 The emitter is connected to the upper end of the motor A phase winding, and the switch tube Q A3 The collector of the motor is connected to the lower end of the A phase winding of the motor, and the switch tube Q A3 The emitter is connected to the negative pole of the DC power supply;

[0039] The diode D A3 The positive pole of the diode D is connected to the negative pole of the DC power supply. A3 The negative pole of the switch tube Q A2 The emitter of diode D A2 The positive pole of the switch tube Q A3 The collector of diode D A2 The negative electrode and the switch tube Q A1 The collector of the diode D A1 The positive electrode of the voltage stabilizing capacitor C1 is connected to the positive electrode of the diode D A1 The negative pole of the switch tube Q A2 The collector.

[0040] The control block diagram of the switched reluctance motor control system based on the four-level power circuit is as follows: Figure 2 As shown, the excitation modes of the proposed switched reluctance motor control system include normal voltage excitation and high voltage excitation. on is the opening angle for starting excitation, θ off is the turn-off angle at which demagnetization begins, represents the opening angle of high voltage excitation, Indicates the cut-off angle of high voltage excitation, where the conduction range of high voltage excitation Included in [θ on ,θ off ]middle.

[0041] The control method comprises the following steps:

[0042] a. Based on the speed deviation between the real-time speed ω and the given speed ω*, the speed controller calculates the reference torque T ref ;

[0043] b. Based on the reference torque T ref and real-time speed ω, and by checking the MTPA optimization control parameter table, the control parameters of the optimized switched reluctance motor are obtained: the opening angle θ at the start of excitation on , the turn-off angle θ at which demagnetization begins off , reference current I ref and the opening angle of high voltage excitation

[0044] c. Based on the actual voltage of the boost capacitor and a given reference voltage The high voltage excitation cut-off angle of the switched reluctance motor is obtained through the closed-loop control of the bus voltage.

[0045] d. Based on the reference current I refThe winding current feedback value and the rotor position feedback value of the switched reluctance motor are used. Current chopping control is used at low speed and angle position control is used at high speed.

[0046] The actual voltage of the boost capacitor is The voltage sensor placed at both ends of the boost capacitor C2 of the four-level power circuit is measured, the current sensor is placed on the bridge arm of the four-level power circuit and connected to each phase winding of the motor, and the position sensor is used to collect the rotor position feedback value of the switched reluctance motor; the controller is used to receive the boost capacitor voltage value of the four-level power circuit collected by the voltage sensor The output end of the controller is connected to the driving circuit of the bridge arm switch tube of each phase on the four-level power circuit.

[0047] The switch reluctance motor control system and control method based on the four-level power circuit adopts the MTPA control strategy based on the four-level power circuit, and realizes the maximum torque-ampere ratio optimization operation by making full use of high-voltage excitation and high-voltage demagnetization. The control parameter table of its MTPA control strategy includes the opening angle θ at the start of excitation on , the turn-off angle θ at which demagnetization begins off , reference current I ref and the opening angle of high voltage excitation The characteristics of the control parameter table are that the high-voltage excitation and high-voltage demagnetization based on the four-level power circuit are used to achieve the maximum torque-ampere ratio operation through the control parameter optimization. The optimization steps include:

[0048] a. Place the high voltage excitation range in the area with smaller inductance, and through angle optimization, find the angle that can maintain the maximum torque-ampere ratio at each torque-speed point.

[0049] b. Based on optimization The automatic control of the bus voltage closed loop performs θ on each torque-speed operating point in the switched reluctance motor drive system based on the four-level power circuit. on ,θ off and I ref Traverse and compare the performance indicators under each set of control parameter combinations to find the control parameter combination that makes the motor most efficient.

[0050] The closed-loop control block diagram of the bus voltage of the control system is as follows: Figure 3 By collecting the output voltage across the boost capacitor Compare it with the preset capacitor voltage The deviation between them is calculated by the voltage regulator to obtain the high-voltage excitation conduction width of the MTPA control strategy. That is, by controlling the time of high-voltage excitation, the discharge amount of the boost capacitor is controlled, and a balance between demagnetization feedback and excitation discharge is achieved during the charge and discharge process of the boost capacitor to achieve a stable bus voltage.

[0051] The bus voltage closed-loop control strategy can not only maintain the charge and discharge balance of the capacitor voltage and realize the automatic control of the bus voltage stability, but also preset the expected value of the boost capacitor voltage. Carry out autonomous regulation to achieve variable voltage control.

[0052] The capacitor protection circuit is as follows Figure 4 As shown, it includes a hysteresis comparator, an AND logic gate, an IGBT driver, an IGBT switch tube Q S and the discharge resistor R S The hysteresis comparator can adjust the upper limit and lower limit of the given capacitor voltage value through a potentiometer.

[0053] The capacitor protection circuit receives the voltage value of the boost capacitor C2 collected by the voltage sensor, compares it with the preset capacitor voltage value of the hysteresis comparator, obtains a logic signal of whether the capacitor needs to be discharged, and outputs a logic signal to the IGBT drive circuit: when the voltage value of the boost capacitor C2 exceeds the set upper limit value, the IGBT switch tube Q is driven. S Turn on, at this time, the boost capacitor C2 is discharged through the resistor R S Discharge; when discharged to the set lower limit, drive the IGBT switch tube Q S Shut down.

[0054] The capacitor protection circuit allows the controller to actively discharge the boost capacitor. When the capacitor charge amount is greater than the discharge amount, the controller executes a protection action and performs active discharge.

[0055] The present invention provides a switch reluctance motor control system and control method based on a four-level power circuit. By optimizing the control strategy and utilizing the high-voltage excitation and high-voltage demagnetization capabilities of the four-level power circuit, the problem that the excitation current is difficult to establish and the demagnetization current easily extends to the inductance drop zone when the motor is running at high speed in the traditional switch reluctance motor drive system is solved; at the same time, a switch reluctance motor control method based on a four-level power circuit is provided, which realizes the stability of the bus voltage and the automatic control of the high-voltage excitation conduction width through the closed-loop control of the boost capacitor voltage, realizes the stable and reliable operation of the system, and at the same time, allows the boost capacitor voltage value to be actively adjusted, so that a more flexible control strategy can be formulated to further optimize the performance of the switch reluctance motor. Finally, by optimizing the control parameters, the high-voltage excitation and high-voltage demagnetization capabilities are fully utilized to improve the operating efficiency of the switch reluctance motor drive system and broaden the speed regulation range of the switch reluctance motor.

[0056] The above description is only a preferred implementation case of the present invention and is not intended to limit the present invention. Without departing from the purpose of the present invention, any technical scheme and implementation example similar to the technical scheme that are designed without creative design shall fall within the protection scope of the present invention.

Claims

1. A switch reluctance motor control system and control method based on a four-level power circuit, characterized in that: It includes a four-level power circuit, a switched reluctance motor, a controller, a voltage sensor, a current sensor, a position sensor and a capacitor protection circuit; The four-level power circuit includes a DC power supply, a voltage stabilizing capacitor C1, a voltage boosting capacitor C2 and a bridge arm circuit composed of a switch tube and a diode. The number of the bridge arm circuits is equal to the number of phases of the motor, and each bridge arm is connected to a phase motor winding. The voltage stabilizing capacitor C1 is connected in parallel with the DC power supply, and the negative electrode of the boosting capacitor C2 is connected in series with the positive electrode of the voltage stabilizing capacitor C1; The bridge arm circuit includes switch tubes Q1, Q2, Q3, and diodes D1, D2, D3; the emitter of the switch tube Q3 in the bridge arm circuit is connected to the negative electrode of the DC power supply, and the collector of the switch tube Q1 is connected to the positive electrode of the boost capacitor C2; The upper end of the motor winding is connected to the emitter of the switch tube Q2, and the lower end of the motor winding is connected to the collector of the switch tube Q3; The voltage sensor is placed at both ends of the boost capacitor C2 of the four-level power circuit, the current sensor is placed on each phase bridge arm of the four-level power circuit and connected to each phase winding of the motor, and the position sensor is used to collect the rotor position feedback value of the switched reluctance motor; The capacitor protection circuit receives the voltage value of the boost capacitor C2 collected by the voltage sensor, compares it with the capacitor voltage value preset by the hysteresis comparator, obtains a logic signal indicating whether the capacitor needs to be discharged, and outputs it to the IGBT drive circuit; The capacitor protection circuit allows the controller to perform active protection actions; The controller is used to receive the boost capacitor voltage value of the four-level power circuit collected by the voltage sensor, the current value of each phase collected by the current sensor, and the rotor position feedback value of the switched reluctance motor collected by the position sensor; the output end of the controller is connected to the driving circuit of the bridge arm switch tube of each phase of the four-level power circuit; The controller of the control system executes the MTPA control strategy to achieve the maximum torque-ampere ratio operation of the switched reluctance motor drive system through optimization control. The control method includes the following steps: a. Based on the speed deviation between the real-time speed ω and the given speed ω*, the speed controller calculates the reference torque T ref ; b. Based on the reference torque T ref and real-time speed ω, and by checking the MTPA control parameter table, the control parameters of the optimized switched reluctance motor are obtained, including the opening angle θ at which the motor phase winding starts to be excited on , the turn-off angle θ at which demagnetization begins off , reference current I ref and the opening angle of high voltage excitation c. Based on the actual voltage of the boost capacitor and a given reference voltage The high voltage excitation cut-off angle of the switched reluctance motor is obtained through the closed-loop control of the bus voltage. d. Based on the reference current I ref The winding current feedback value and the rotor position feedback value of the switched reluctance motor are used. Current chopping control is used at low speed, and angle position control is used at high speed. The switch reluctance motor control system based on the four-level power circuit and the control method thereof adopt the MTPA control strategy based on the four-level power circuit, make full use of high-voltage excitation and high-voltage demagnetization, and achieve maximum torque-ampere ratio optimized operation through optimized control.

2. According to the switch reluctance motor control system and control method based on the four-level power circuit of claim 1, the stabilization of the high-voltage bus voltage is achieved by the bus voltage closed-loop control based on the four-level power circuit and the boost capacitor protection circuit; The bus voltage closed-loop control collects the output voltage at both ends of the boost capacitor. Compare it with the preset capacitor voltage The deviation between them is calculated by the voltage regulator to obtain the high-voltage excitation conduction width of the MTPA control strategy. That is, by controlling the time of high-voltage excitation, the discharge amount of the boost capacitor is controlled, and the balance between demagnetization feedback and excitation discharge is achieved during the charge and discharge process of the boost capacitor to achieve a stable bus voltage; The bus voltage closed-loop control strategy can not only achieve the charge and discharge balance of the capacitor voltage and achieve bus voltage stability through automatic control, but also can autonomously adjust the boost capacitor voltage and achieve variable voltage control; The capacitor protection circuit is composed of a hysteresis comparator, an AND logic gate, an IGBT driver, an IGBT switch tube Q S and the discharge resistor R S constitute; The hysteresis comparator adjusts the upper and lower limits of the given capacitor voltage value through a potentiometer; The capacitor protection circuit receives the voltage value of the boost capacitor C2 collected by the voltage sensor, and when the voltage value of the boost capacitor C2 exceeds the set upper limit value, the IGBT switch tube Q is driven. S Turn on, at this time, the boost capacitor C2 is discharged through the resistor R S Discharge; when discharged to the set lower limit, drive the IGBT switch tube Q S Shut down; The capacitor protection circuit allows the controller to actively perform capacitor discharge action. When the capacitor charge amount is greater than the discharge amount, the controller executes a protection action and performs active discharge.

3. According to the switch reluctance motor control system and control method based on the four-level power circuit of claim 1, the control parameter table of the MTPA control strategy includes the opening angle θ at which the excitation starts on , the turn-off angle θ at which demagnetization begins off , reference current I ref and the opening angle of high voltage excitation The control parameter table is characterized by high-voltage excitation and high-voltage demagnetization based on a four-level power circuit, which is obtained by traversal optimization. The optimization steps include: a. Place the high voltage excitation range in the area with smaller inductance, and through angle optimization, traverse to find the maximum torque-ampere ratio at each torque-speed point. To achieve efficient and rapid excitation; b. Based on optimization The automatic control of the bus voltage closed loop performs θ on each torque-speed operating point in the switched reluctance motor drive system based on the four-level power circuit. on ,θ off and I ref Traverse and compare the performance indicators under each set of control parameter combinations to find the control parameter combination that makes the motor most efficient.

Images