CN210927489U - Three-phase switch reluctance motor fast braking control system - Google Patents

Abstract

The utility model discloses a three-phase switched reluctance motor rapid braking control system, which comprises a rectifier unit, a power conversion unit, a control unit and a braking unit. The braking unit includes a braking IGBT module and a braking resistor. The braking IGBT The module is connected in series with a braking resistor and then connected to both ends of the rectifier circuit. The control terminal of the braking IGBT module is connected with an IGBT drive circuit. By using a braking unit composed of a braking IGBT module and a braking resistor, the braking current closed-loop is realized during the braking process. The utility model adopts a braking unit composed of a braking IGBT module and a braking resistor to realize a closed-loop braking current during the braking process. Under the premise that the hardware circuit of the control system allows, the switched reluctance motor and the shaft system can reach the maximum braking torque that can be tolerated, so as to achieve the shortest braking time.

Description

A three-phase switched reluctance motor rapid braking control system

technical field

The utility model relates to the technical field of a switched reluctance motor drive system, in particular to a three-phase switched reluctance motor fast braking control system.

Background technique

With the rapid development of the motor industry, the switched reluctance motor has more and more obvious advantages due to its wide speed control range, high efficiency, long life and high investment benefit of the speed control system, and has been widely used in metallurgy, machinery, petroleum, Ports, mines, aerospace and other fields. In many application fields, such as machinery, tunnel drilling and other industries, the motor needs to rotate forward and reverse frequently. Therefore, the length of the braking time directly determines the working efficiency, which is also proposed for the braking time of the switched reluctance motor. more stringent requirements.

The traditional switched reluctance motor and its transmission system mostly use electromagnetic brakes for braking. This braking method not only requires the installation of electromagnetic braking equipment in the already narrow operating space, but also generates a lot of heat during the braking process. Additional cooling equipment is installed to dissipate heat, and frequent braking cannot be achieved. More importantly, because the switched reluctance motor controller needs to stop working first during electromagnetic braking, when the electromagnetic brake stops after braking, the switched reluctance motor controller switches to the working state, which takes a long time to brake. And the braking efficiency is low. Under the current situation of increasing requirements for frequent braking and rapid designation, the braking method of the existing switched reluctance motor speed control system can no longer meet the needs of use.

It is bound to seek a braking method with high efficiency, short braking time, precise control of braking time, and frequent braking to solve the problem of fast, precise and efficient braking of the switched reluctance motor speed control system.

Utility model content

The purpose of the present utility model is to provide a three-phase switched reluctance motor rapid braking control system, which can realize the rapid braking and frequent braking of the switched reluctance motor, and does not need to add a heat dissipation system, reduces the equipment cost, and has both the The advantages of high reliability and strong stability.

The technical scheme adopted by the utility model is:

A three-phase switched reluctance motor rapid braking control system includes a rectifier unit, a power conversion unit and a control unit, the rectifier unit provides the power current required by the control system through a DC bus, and also includes a braking unit;

The rectifier unit is respectively connected to the three-phase coils of the three-phase switched reluctance motor through the power conversion unit;

The power conversion unit includes three-way asymmetric half-bridge power circuits, and the three-way asymmetric half-bridge power circuits are connected with the three-phase coils of the three-phase switched reluctance motor in one-to-one correspondence;

The braking unit includes a braking IGBT module and a braking resistor, the braking IGBT module is connected in series with the braking resistor and then connected to both ends of the rectifier circuit, and the control terminal of the braking IGBT module is connected with an IGBT drive circuit;

The control unit includes a DSP module, a sampling module and other peripheral circuits. The sampling module is respectively connected to the rectifier unit, the power conversion unit, the braking unit and the rotary encoder of the three-phase switched reluctance motor. The sampling module collects the control system through the voltage sensor and the current sensor. The sampling module collects the position signal of the three-phase switched reluctance motor through the rotary encoder, and the DSP module sends the PWM pulse signal to the power conversion unit and the braking unit according to the signal collected by the sampling module.

Further, the sampling module converts the signals generated by the voltage sensor, the current sensor and the rotary encoder into an analog signal that can be directly processed by the DSP module. The voltage sensor is connected in parallel at both ends of the DC bus and used to collect the voltage and current at both ends of the DC bus. The sensor includes a first current sensor and a second current sensor. The first current sensor is connected to the rectifier circuit and collects the DC bus current. The second current sensor is connected to the braking unit and collects the current consumed by the braking resistor in the power generation operation state.

Further, the asymmetric half-bridge power circuit includes two power IGBT modules, the two power IGBT modules are respectively connected to the incoming wire end and the outgoing wire end of the corresponding coil of the three-phase switched reluctance motor, and the control end of each power IGBT module is An IGBT drive circuit is connected.

Further, a freewheeling diode is connected in anti-parallel between the collectors and the emitters of the braking IGBT module and the power IGBT module.

Further, the IGBT drive circuit adopts an isolation amplifier circuit.

Further, the sampling module adopts a differential amplifier circuit.

The utility model has the following beneficial effects:

(1) By using the braking unit composed of the braking IGBT module and the braking resistor, the braking current closed-loop is realized during the braking process. Under the premise of the hardware circuit of the control system, the switch reluctance motor and the shaft system can reach the maximum braking torque that can be tolerated, so as to achieve the shortest braking time; by using the braking resistor as the consumption load of the braking unit, the switch The energy generated by the reluctance motor during the braking process is consumed in the braking resistor in the form of heat. Since the braking resistor is equipped with a cooling system, it is further guaranteed that frequent and repeated braking can be achieved;

(2) Switched reluctance motor and control system can realize braking function only by adding braking unit, no need to add additional cooling system. Compared with traditional electromagnetic braking system, special equipment such as special power supply and electromagnetic control system is not required, and space is utilized. High efficiency, can significantly improve economic benefits, reduce equipment costs, and have the advantages of high reliability and stability;

(3) Through the control method of the present invention, the rapid braking and frequent braking of the switched reluctance motor are realized, and the switched reluctance motor and the shaft system are converted from the electric running state to the braking state or from the braking end. Switching to the running state without any mechanical operation, the time is only a few instruction cycles of the DSP module running, and the switching time can reach the millisecond level, which effectively improves the braking efficiency of the present invention; at the same time, the speed and current closed loop is realized in the braking process. Control, and synchronously receive speed and current signals, and synchronously adjust the relationship between braking time, braking current and shafting speed through the DSP module to achieve rapid braking, and can also stop the shafting within the specified braking time. Rotation, high precision, high reliability and high flexibility;

(4) By realizing the double closed-loop control of the braking current and the bus voltage during the braking process, the damage to the control system such as bus overvoltage and overcurrent of the braking unit caused by the asynchrony of the bus voltage and the peak value of the braking current is effectively avoided. When the situation occurs, the reliability and stability of the present invention are further improved.

Description of drawings

Fig. 1 is the structural representation of the control system in the utility model;

FIG. 2 is a flow chart of the control method of the present invention.

Detailed ways

As shown in Figure 1, the present invention includes a rectifier unit, a power conversion unit, a control unit and a braking unit, and the rectifier unit provides the power current required by the control system through the DC bus;

The rectifier unit is respectively connected to the three-phase coils of the three-phase switched reluctance motor through the power conversion unit;

The power conversion unit includes three-way asymmetric half-bridge power circuits, and the three-way asymmetric half-bridge power circuits are connected with the three-phase coils of the three-phase switched reluctance motor in one-to-one correspondence;

The braking unit includes a braking IGBT module and a braking resistor, the braking IGBT module is connected in series with the braking resistor and then connected to both ends of the rectifier circuit, and the control terminal of the braking IGBT module is connected with an IGBT drive circuit;

The control unit includes a DSP module, a sampling module and other peripheral circuits. The sampling module is respectively connected to the rectifier unit, the power conversion unit, the braking unit and the rotary encoder of the three-phase switched reluctance motor. The sampling module collects the control system through the voltage sensor and the current sensor. The sampling module collects the position signal of the three-phase switched reluctance motor through the rotary encoder, and the DSP module sends the PWM pulse signal to the power conversion unit and the braking unit according to the signal collected by the sampling module.

In order to better understand the present utility model, the technical solutions of the present utility model are further described below with reference to the accompanying drawings.

As shown in Figure 1, the present utility model discloses a three-phase switched reluctance motor rapid braking control system, including a rectifier unit, a power conversion unit, a control unit and a braking unit, and the rectifier unit provides the required control system through the DC bus. power current.

The three-phase switched reluctance motor can operate in four quadrants, and the control unit makes the three-phase switched reluctance motor work in the electric state or the power generation state according to the control requirements.

The rectification unit is respectively connected to the three-phase coils of the three-phase switched reluctance motor through the power conversion unit.

The power conversion unit includes a three-way asymmetric half-bridge power circuit, and the three-way asymmetric half-bridge power circuit is connected with the three-phase coils of the three-phase switched reluctance motor in one-to-one correspondence. The asymmetric half-bridge power circuit includes two power IGBT modules Q, the two power IGBT modules Q are respectively connected in series with the incoming and outgoing ends of the corresponding coils of the three-phase switched reluctance motor, and the control end of each power IGBT module Q is connected with a IGBT drive circuit, IGBT drive circuit adopts isolation amplifier circuit; between the collector and emitter of each power IGBT module Q, there is a freewheeling diode D in anti-parallel. The inductive reverse voltage will cause the IGBT to be broken down. The increase of the freewheeling diode D can short-circuit the self-inductive reverse voltage, and it is equivalent to disconnecting the forward voltage. Therefore, the IGBT can be effectively protected.

The braking unit includes a braking IGBT module Q' and a braking resistor R. During the braking process, the mechanical energy of the switched reluctance motor is converted into electrical energy, and the electrical energy generated by braking is converted into thermal energy through the braking resistor R and consumed.

The brake IGBT module Q' collector and emitter are connected in series with the braking resistor R and then connected to both ends of the DC bus. The control end of the braking IGBT module Q' is connected with an IGBT drive circuit, and the IGBT drive circuit is used to drive the braking IGBT module Q' The IGBT drive circuit preferably adopts an isolation amplifier circuit; there is a freewheeling diode D' in anti-parallel between the collector and the emitter of the braking IGBT module Q', because the two ends of the IGBT turn off a very high self-voltage. The inductive reverse voltage will cause the IGBT to be broken down. The increase of the freewheeling diode D' can short-circuit the self-inductive reverse voltage, and it is equivalent to disconnecting the forward voltage. Therefore, the IGBT can be effectively protected.

The control unit includes a DSP module, a sampling module and other peripheral circuits. The sampling module is respectively connected to the rectifier unit, the power conversion unit, the braking unit and the rotary encoder of the three-phase switched reluctance motor. The sampling module collects the control system through the voltage sensor and the current sensor. The sampling module collects the stator and rotor position information of the three-phase switched reluctance motor through the rotary encoder, and the DSP module sends PWM pulse signals to the power conversion unit and the braking unit according to the signals collected by the sampling module.

The sampling module converts the signals generated by the voltage sensor, the current sensor and the rotary encoder into an analog signal that can be directly processed by the DSP module. The voltage sensor is connected in parallel at both ends of the DC bus and is used to collect the voltage at both ends of the DC bus. The current sensor includes a first current A sensor and a second current sensor, the first current sensor is connected to the rectifier circuit and collects the DC bus current, and the second current sensor is connected to the braking unit and collects the current consumed by the braking resistor in the power generation operation state. The sampling module preferably adopts a differential amplifier circuit, and the voltage, current and position signals are converted into analog signals that can be directly processed by the DSP module through the differential amplifier circuit.

The fast braking control system disclosed in the present invention realizes a closed-loop braking current during braking by using a braking unit composed of a braking IGBT module Q' and a braking resistor R, and at the same time, the DSP module can adjust the motor during braking The energy generated is equal to the energy consumed by the resistance, and under the premise of the control system hardware circuit, the switched reluctance motor and the shaft system can reach the maximum braking torque that can be tolerated, so as to achieve the shortest braking time; The dynamic resistance R is used as the consumption load of the braking unit, so that the energy generated by the switched reluctance motor during the braking process is dissipated in the braking resistance R in the form of heat. and braking repeatedly.

The control method based on the above-mentioned three-phase switched reluctance motor rapid braking control system according to the present invention includes the following steps:

A. The control unit collects the signal of the rotary encoder of the three-phase switched reluctance motor to obtain the relative position of the rotor and the stator.

B. The control unit judges whether the braking signal is received, if not, it goes to the next step, and if it is received, it goes to step D.

C. The excitation current is applied to the inductance rising region of the three-phase switched reluctance motor, and the three-phase switched reluctance motor enters the electric operation mode. Specifically:

The power unit applies the excitation current to the inductance rise area of the three-phase switched reluctance motor to drive the three-phase switched reluctance motor to run electrically. The power unit current flows from the positive pole of the bus bar to the motor winding after being modulated by the power IGBT module Q, and then flows back to the rectifier unit The negative pole of the bus bar;

D. The excitation current is applied to the inductance drop area of the three-phase switched reluctance motor, the three-phase switched reluctance motor enters the power generation operation mode, and the braking unit quickly brakes the three-phase switched reluctance motor; the specific process is as follows:

d1: After receiving the braking signal, the rectifier unit applies excitation current to the inductance drop area of the three-phase switched reluctance motor, so that the three-phase switched reluctance motor generates electricity and operates, and converts the mechanical energy of the shaft system rotation into electrical energy;

d2: The DSP module sends the braking PWM pulse to the braking IGBT drive circuit, the braking IGBT module Q' is turned on, and the braking unit starts to work;

d3: The generation current of the three-phase switched reluctance motor flows from one end of the motor winding to the positive pole of the motor busbar, flows to the braking resistor R through the braking IGBT module Q', and then flows back to the other end of the motor winding through the negative pole of the busbar;

d4: The electric energy generated by the braking unit is consumed in the braking resistor R in the form of heat;

d5: During the braking process, the DSP module sends the driving PWM pulse to the power unit through the collected current information and voltage information, adjusts the generation current of the three-phase switched reluctance motor, realizes the double closed-loop control of the braking current and the bus voltage, and makes the power generation Power and braking power are balanced, and the braking effect is finally achieved.

The specific process of adjusting the generated current of the three-phase switched reluctance motor is as follows:

The DSP module collects the generation current of the three-phase switched reluctance motor, the current flowing through the braking load in the braking unit and the voltage across the rectifier unit;

d5.2: Calculate the power generated by the motor and the power consumption of the braking resistor;

d5.3: According to the power generated by the motor and the power consumption of the braking resistor, the DSP module adjusts the duty cycle of the driving PWM pulse through the PI operation, and adjusts the generating current of the three-phase switched reluctance motor and the braking current of the braking unit, so that the motor generates electricity. The power and the power consumption of the braking resistor are kept in balance. Specifically: if the power consumption of the braking resistor R is greater than the power generated by the motor, reduce the PWM pulse duty cycle of the IGBT module of the braking circuit; if the power consumption of the braking resistor is less than the power generated by the motor, increase the PWM pulse of the braking circuit IGBT module duty cycle.

It should be pointed out that how to realize the change of the power generation current by driving different power IGBT modules Q to conduct is determined by calculating the relationship between the branch current and the final power generation current. This calculation method is an existing mature technology, so in This will not be repeated here.

The greater the generating current, the greater the braking power and the shorter the braking time. By adjusting the generating power and braking power, the purpose of adjusting the braking time is achieved. The braking time can also be input to the DSP module. The DSP module performs PID adjustment and control according to the magnitude of the generating current and the speed of the motor speed drop, so that the motor and the shaft system stop within a specified time, thereby realizing the timing braking function.

The fast braking control method of the utility model realizes the fast braking and frequent braking of the switched reluctance motor, and makes the switched reluctance motor and the shaft system switch from the electric running state to the braking state or from the braking end. In the running state, there is no mechanical operation, the time is only a few instruction cycles of the DSP model running, and the switching time can reach the millisecond level, which effectively improves the braking efficiency of the utility model; at the same time, the closed-loop speed and current are realized in the braking process. Control, and synchronously receive speed and current signals, and synchronously adjust the relationship between braking time, braking current and shafting speed through the DSP module to achieve rapid braking, and can also stop the shafting within the specified braking time. Rotation, high precision, high reliability and high flexibility.

Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present utility model, but not to limit them; although the present utility model has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should The technical solutions described in the foregoing embodiments can still be modified, or some or all of the technical features thereof can be equivalently replaced, and these modifications or replacements do not make the essence of the corresponding technical solutions depart from the scope of the technical solutions of the embodiments of the present invention .

Claims (6)

1. a three-phase switched reluctance motor fast braking control system, comprising a rectifier unit, a power conversion unit and a control unit, the rectifier unit provides the required power current of the control system by the DC bus, it is characterized in that: also comprise a braking unit; The rectifier unit is respectively connected to the three-phase coils of the three-phase switched reluctance motor through the power conversion unit; The power conversion unit includes three-way asymmetric half-bridge power circuits, and the three-way asymmetric half-bridge power circuits are connected with the three-phase coils of the three-phase switched reluctance motor in one-to-one correspondence; The braking unit includes a braking IGBT module and a braking resistor, the braking IGBT module is connected in series with the braking resistor and then connected to both ends of the rectifier circuit, and the control terminal of the braking IGBT module is connected with an IGBT drive circuit; The control unit includes a DSP module, a sampling module and other peripheral circuits. The sampling module is respectively connected to the rectifier unit, the power conversion unit, the braking unit and the rotary encoder of the three-phase switched reluctance motor. The sampling module collects the control system through the voltage sensor and the current sensor. The sampling module collects the position signal of the three-phase switched reluctance motor through the rotary encoder, and the DSP module sends the PWM pulse signal to the power conversion unit and the braking unit according to the signal collected by the sampling module. 2. The three-phase switched reluctance motor fast braking control system according to claim 1, wherein the sampling module converts the signals generated by the voltage sensor, the current sensor and the rotary encoder into a signal that the DSP module can directly process. Analog signal, the voltage sensor is connected in parallel at both ends of the DC bus and is used to collect the voltage at both ends of the DC bus. The current sensor includes a first current sensor and a second current sensor. The first current sensor is connected to the rectifier circuit and collects the current of the DC bus. The second current The sensor is connected in the braking unit and collects the current consumed by the braking resistor in the running state of power generation. 3 . The three-phase switched reluctance motor fast braking control system according to claim 2 , wherein the asymmetric half-bridge power circuit comprises two power IGBT modules, and the two power IGBT modules are respectively connected to the three-phase switch. 4 . The reluctance motor corresponds to the incoming wire end and the outgoing wire end of the coil, and the control end of each power IGBT module is connected with an IGBT drive circuit. 4 . The three-phase switched reluctance motor fast braking control system according to claim 3 , wherein a freewheeling diode is connected in anti-parallel between the collector and the emitter of the braking IGBT module and the power IGBT module. 5 . . 5 . The three-phase switched reluctance motor rapid braking control system according to claim 2 , wherein the IGBT drive circuit adopts an isolation amplifier circuit. 6 . 6 . The three-phase switched reluctance motor rapid braking control system according to claim 2 , wherein the sampling module adopts a differential amplifier circuit. 7 .

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