阅读说明：本技术 一种三相开关磁阻电机快速制动控制系统及控制方法 (Three-phase switched reluctance motor rapid braking control system and control method ) 是由 刘平顺 吴宣东 张�浩 赵跃东 张道洋 范宏伟 刘建波 周良 逵振雨 高乔 张虎 于 2019-12-10 设计创作，主要内容包括：本发明公开了一种三相开关磁阻电机快速制动控制系统及控制方法，包括整流单元、功率变换单元、控制单元和制动单元，通过采用制动IGBT模块和制动电阻构成的制动单元，制动过程中实现制动电流闭环，实现了开关磁阻电机的快速制动和频繁制动，同时，在制动过程中实现转速、电流闭环控制，且同步接收转速、电流信号，通过DSP模块同步调节制动时间、制动电流和轴系转速之间的关系，实现快速制动的同时，还能够在指定制动时间内使轴系停止转动，精确度高，可靠性强，灵活度高。(The invention discloses a rapid braking control system and a rapid braking control method for a three-phase switched reluctance motor, which comprise a rectifying unit, a power conversion unit, a control unit and a braking unit, wherein a braking unit consisting of a braking IGBT module and a braking resistor is adopted, a braking current closed loop is realized in the braking process, rapid braking and frequent braking of the switched reluctance motor are realized, meanwhile, the rotating speed and current closed loop control is realized in the braking process, the rotating speed and current signals are synchronously received, the relation among the braking time, the braking current and the rotating speed of a shaft system is synchronously adjusted through a DSP module, the shaft system can be stopped rotating within the appointed braking time, and the system has high accuracy, strong reliability and high flexibility.)

1. The utility model provides a three-phase switch reluctance machine fast brake control system, includes rectifier unit, power conversion unit and the control unit, and the rectifier unit provides the required power current of control system through direct current bus, its characterized in that: the brake device also comprises a brake unit;

the rectifying unit is respectively connected with three-phase coils of the three-phase switched reluctance motor through the power conversion unit;

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

the brake unit comprises a brake IGBT module and a brake resistor, the brake IGBT module is connected with the two ends of the rectifying circuit after being connected with the brake resistor in series, and the control end of the brake IGBT module is connected with an IGBT driving circuit;

the control unit comprises a DSP module, a sampling module and other peripheral circuits, the sampling module is respectively connected with the rectifying unit, the power conversion unit, the braking unit and a rotary encoder of the three-phase switch reluctance motor, the sampling module acquires voltage signals and current signals of the control system through a voltage sensor and a current sensor, the sampling module acquires position signals of the three-phase switch 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 acquired by the sampling module.

2. The three-phase switched reluctance motor rapid braking control system according to claim 1, wherein: the sampling module converts signals generated by the voltage sensor, the current sensor and the rotary encoder into analog quantity signals which can be directly processed by the DSP module, the voltage sensor is connected in parallel with two ends of a direct current bus and used for collecting voltages at two ends of the direct current bus, the current sensor comprises a first current sensor and a second current sensor, the first current sensor is connected with the rectifying circuit and collects current of the direct current bus, and the second current sensor is connected in the braking unit and collects current consumed by the braking resistor in a power generation running state.

3. The three-phase switched reluctance motor rapid braking control system according to claim 2, wherein: the asymmetric half-bridge power circuit comprises two power IGBT modules, the two power IGBT modules are respectively connected with a wire inlet end and a wire outlet end of a corresponding coil of the three-phase switched reluctance motor, and a control end of each power IGBT module is connected with an IGBT driving circuit.

4. The three-phase switched reluctance motor rapid braking control system of claim 3, wherein: and freewheeling diodes are reversely connected in parallel between the collectors and the emitters of the braking IGBT module and the power IGBT module.

5. The three-phase switched reluctance motor rapid braking control system according to claim 2, wherein: the IGBT driving circuit adopts an isolation amplifying circuit.

6. The three-phase switched reluctance motor rapid braking control system according to claim 2, wherein: the sampling module adopts a differential amplification circuit.

7. A control method of the three-phase switched reluctance motor rapid braking control system based on claim 2, characterized in that: the method comprises the following steps:

A. the control unit acquires signals of a rotary encoder of the three-phase switch reluctance motor to acquire the relative position of a rotor and a stator;

B. the control unit judges whether a braking signal is received, if the braking signal is not received, the next step is carried out, and if the braking signal is received, the step D is carried out;

C. applying exciting current to an inductance rising area of the three-phase switched reluctance motor, and enabling the three-phase switched reluctance motor to enter an electric operation mode;

the method specifically comprises the following steps: the power unit applies exciting current to an inductance rising area of the three-phase switched reluctance motor to drive the three-phase switched reluctance motor to run electrically, and the current of the rectification unit flows to a motor winding after being modulated by the power IGBT module from the positive pole of the bus and then flows back to the negative pole of the bus of the rectification unit;

D. applying exciting current to an inductance descending area of the three-phase switched reluctance motor, enabling the three-phase switched reluctance motor to enter a power generation operation mode, and rapidly braking the three-phase switched reluctance motor; the specific process is as follows:

d 1: after receiving the braking signal, the power unit applies exciting current to an inductance reduction area of the three-phase switched reluctance motor to enable the three-phase switched reluctance motor to generate electricity and operate, and mechanical energy generated by rotation of a shafting is converted into electric energy;

d 2: the DSP module sends a braking PWM pulse to the braking IGBT driving circuit, the braking IGBT module is conducted, and the braking unit starts to work;

d 3: the power generation current of the three-phase switched reluctance motor flows from one end of the motor winding to the positive pole of the motor bus, flows to the brake resistor through the brake IGBT module, and then flows back to the other end of the motor winding through the negative pole of the bus;

d 4: the electric energy generated by the brake unit is dissipated on the brake resistor in the form of heat;

d 5: in the braking process, the DSP module sends and drives PWM pulses to the power unit through the acquired current information and voltage information, adjusts the generating current of the three-phase switched reluctance motor, realizes the double closed-loop control of the braking current and the bus voltage, balances the generating power and the braking power, and finally realizes the braking effect.

8. The three-phase switched reluctance motor quick brake control system of claim 7, wherein: the specific process of step d5 is as follows:

d 5.1: the DSP module collects the generating current of the three-phase switched reluctance motor, the current flowing through a braking load in the braking unit and the voltage at two ends of the rectifying unit;

d 5.2: calculating the power generation power of the motor and the power consumption of the brake resistor;

d 5.3: according to the generated power of the motor and the consumed power of the brake resistor, the DSP module adjusts the duty ratio of the driving PWM pulse through PI operation, and adjusts the generated current of the three-phase switched reluctance motor and the brake current of the brake unit, so that the generated power of the motor and the consumed power of the brake resistor are kept balanced.

9. The three-phase switched reluctance motor quick brake control system of claim 8, wherein: the step d5.3 is specifically as follows: if the consumed power of the brake resistor is larger than the power generated by the motor, reducing the PWM pulse duty ratio of the IGBT module of the brake circuit; and if the consumed power of the brake resistor is less than the power generated by the motor, the PWM pulse duty ratio of the IGBT module of the brake circuit is increased.

10. The three-phase switched reluctance motor quick brake control system of claim 7, wherein: the specific process of the step d5 is as follows: and the DSP module inputs braking time and performs PID (proportion integration differentiation) regulation control according to the generated current and the reduction rate of the rotating speed of the motor, so that the motor and a shaft system stop within a specified time, and a timing braking function is realized.

Technical Field

The invention relates to the technical field of a driving system of a switched reluctance motor, in particular to a rapid braking control system and a rapid braking control method of a three-phase switched reluctance motor.

Background

With the rapid development of the motor industry, the advantages of the switched reluctance motor are more and more remarkable due to the advantages of a speed regulating system, such as wide speed regulating range, high efficiency, long service life, high investment benefit and the like, and the switched reluctance motor is widely applied to the fields of metallurgy, machinery, petroleum, ports and docks, mines, aerospace and the like. In many application fields, such as industries of machinery, tunnel drilling and the like, frequent forward rotation and reverse rotation of the motor are required, so that the braking time directly determines the working efficiency, and the braking time of the switched reluctance motor also puts more strict requirements.

Traditional switched reluctance motor and transmission system thereof adopt electromagnetic braking ware to brake more, and this kind of braking mode not only needs install electromagnetic braking equipment additional with regard to this narrow and small operating space, still can produce a large amount of heats at the braking process, needs additionally to install heat dissipation equipment additional and dispels the heat, can't realize frequent braking. More importantly, the switched reluctance motor controller needs to stop working firstly during electromagnetic braking, and is switched to a working state after the electromagnetic brake stops after braking is finished, so that the braking time is long and the braking efficiency is low. Under the condition that the requirements for frequent braking and quick designation are increasingly improved, the braking mode of the conventional speed regulating system of the switched reluctance motor cannot meet the use requirement.

The problem of rapid, accurate and efficient braking of a speed regulating system of a switched reluctance motor is solved by seeking a braking mode which has high efficiency, short braking time, accurate control of the braking time and frequent braking.

Disclosure of Invention

The invention aims to provide a rapid braking control system and a rapid braking control method for a three-phase switched reluctance motor, which can realize rapid braking and frequent braking of the switched reluctance motor, do not need to additionally add a heat dissipation system, reduce equipment cost, and have the advantages of high reliability and strong stability.

The technical scheme adopted by the invention is as follows:

a three-phase switch reluctance motor rapid braking control system comprises a rectifying unit, a power conversion unit and a control unit, wherein the rectifying unit provides power current required by the control system through a direct current bus, and the three-phase switch reluctance motor rapid braking control system also comprises a braking unit;

the rectifying unit is respectively connected with three-phase coils of the three-phase switched reluctance motor through the power conversion unit;

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

the brake unit comprises a brake IGBT module and a brake resistor, the brake IGBT module is connected with the two ends of the rectifying circuit after being connected with the brake resistor in series, and the control end of the brake IGBT module is connected with an IGBT driving circuit;

the control unit comprises a DSP module, a sampling module and other peripheral circuits, the sampling module is respectively connected with the rectifying unit, the power conversion unit, the braking unit and a rotary encoder of the three-phase switch reluctance motor, the sampling module acquires voltage signals and current signals of the control system through a voltage sensor and a current sensor, the sampling module acquires position signals of the three-phase switch 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 acquired by the sampling module.

Furthermore, the sampling module converts signals generated by the voltage sensor, the current sensor and the rotary encoder into analog quantity signals which can be directly processed by the DSP module, the voltage sensor is connected in parallel with two ends of the direct current bus and used for collecting voltages at two ends of the direct current bus, the current sensor comprises a first current sensor and a second current sensor, the first current sensor is connected with the rectifying circuit and collects current of the direct current bus, and the second current sensor is connected in the braking unit and collects current consumed by the braking resistor in a power generation operation state.

Furthermore, the asymmetric half-bridge power circuit comprises two power IGBT modules, the two power IGBT modules are respectively connected with the wire inlet end and the wire outlet end of the corresponding coil of the three-phase switched reluctance motor, and the control end of each power IGBT module is connected with an IGBT driving circuit.

Furthermore, freewheeling diodes are connected in anti-parallel between the collectors and the emitters of the braking IGBT module and the power IGBT module.

Further, the IGBT driving circuit adopts an isolation amplifying circuit.

Further, the sampling module adopts a differential amplification circuit.

The invention also discloses a control method based on the three-phase switched reluctance motor rapid braking control system, which comprises the following steps:

A. the control unit acquires signals of a rotary encoder of the three-phase switch reluctance motor to acquire the relative position of a rotor and a stator;

B. the control unit judges whether a braking signal is received, if the braking signal is not received, the next step is carried out, and if the braking signal is received, the step D is carried out;

C. applying exciting current to an inductance rising area of the three-phase switched reluctance motor, and enabling the three-phase switched reluctance motor to enter an electric operation mode;

the method specifically comprises the following steps: the power unit applies exciting current to an inductance rising area of the three-phase switched reluctance motor to drive the three-phase switched reluctance motor to run electrically, and the current of the rectification unit flows to a motor winding after being modulated by the power IGBT module from the positive pole of the bus and then flows back to the negative pole of the bus of the rectification unit;

D. applying exciting current to an inductance descending area of the three-phase switched reluctance motor, enabling the three-phase switched reluctance motor to enter a power generation operation mode, and rapidly braking the three-phase switched reluctance motor; the specific process is as follows:

d 1: after receiving the braking signal, the power unit applies exciting current to an inductance reduction area of the three-phase switched reluctance motor to enable the three-phase switched reluctance motor to generate electricity and operate, and mechanical energy generated by rotation of a shafting is converted into electric energy;

d 2: the DSP module sends a braking PWM pulse to the braking IGBT driving circuit, the braking IGBT module is conducted, and the braking unit starts to work;

d 3: the power generation current of the three-phase switched reluctance motor flows from one end of the motor winding to the positive pole of the motor bus, flows to the brake resistor through the brake IGBT module, and then flows back to the other end of the motor winding through the negative pole of the bus;

d 4: the electric energy generated by the brake unit is dissipated on the brake resistor in the form of heat;

d 5: in the braking process, the DSP module sends and drives PWM pulses to the power unit through the acquired current information and voltage information, adjusts the generating current of the three-phase switched reluctance motor, realizes the double closed-loop control of the braking current and the bus voltage, balances the generating power and the braking power, and finally realizes the braking effect.

8. The three-phase switched reluctance motor quick brake control system of claim 7, wherein: the specific process of step d5 is as follows:

d 5.1: the DSP module collects the generating current of the three-phase switched reluctance motor, the current flowing through a braking load in the braking unit and the voltage at two ends of the rectifying unit;

d 5.2: calculating the power generation power of the motor and the power consumption of the brake resistor;

d 5.3: according to the generated power of the motor and the consumed power of the brake resistor, the DSP module adjusts the duty ratio of the driving PWM pulse through PI operation, and adjusts the generated current of the three-phase switched reluctance motor and the brake current of the brake unit, so that the generated power of the motor and the consumed power of the brake resistor are kept balanced.

Further, the step d5.3 specifically includes: if the consumed power of the brake resistor is larger than the power generated by the motor, reducing the PWM pulse duty ratio of the IGBT module of the brake circuit; and if the consumed power of the brake resistor is less than the power generated by the motor, the PWM pulse duty ratio of the IGBT module of the brake circuit is increased.

Further, the specific process of step d5 is as follows: and the DSP module inputs braking time and performs PID (proportion integration differentiation) regulation control according to the generated current and the reduction rate of the rotating speed of the motor, so that the motor and a shaft system stop within a specified time, and a timing braking function is realized.

The invention has the following beneficial effects:

(1) the braking unit consisting of the braking IGBT module and the braking resistor is adopted, so that a braking current closed loop is realized in the braking process, meanwhile, the DSP module can adjust the energy generated by the motor and the energy consumed by the resistor to be equal in the braking process, and the switched reluctance motor and the shaft system can reach the maximum braking torque which can be borne by the switched reluctance motor and the shaft system on the premise of permission of a hardware circuit of a control system, so that the shortest braking time is reached; the brake resistor is used as the consumption load of the brake unit, so that the energy generated by the switched reluctance motor in the braking process is consumed on the brake resistor in the form of heat;

(2) the switched reluctance motor and the control system can realize the braking function only by adding the braking unit without additionally adding a heat dissipation system, and compared with the traditional electromagnetic braking system, the switched reluctance motor and the control system do not need special equipment such as a special power supply, an electromagnetic control system and the like, have high space utilization rate, can obviously improve the economic benefit, reduce the equipment cost, and simultaneously have the advantages of high reliability and strong stability;

(3) by the control method, the rapid braking and the frequent braking of the switched reluctance motor are realized, the switched reluctance motor and the shafting are switched to the braking state from the electric operation state or to the operation state from the braking end, no mechanical operation is needed, the time is only a few instruction cycles of the operation of the DSP module, the switching time can reach millisecond level, and the braking efficiency of the invention is effectively improved; meanwhile, closed-loop control of the rotating speed and the current is realized in the braking process, the rotating speed and the current signals are synchronously received, the relation among the braking time, the braking current and the rotating speed of the shafting is synchronously adjusted through the DSP module, quick braking is realized, the shafting can be stopped to rotate within the appointed braking time, and the system has high accuracy, strong reliability and high flexibility;

(4) by realizing double closed-loop control of the braking current and the bus voltage in the braking process, the situations of damage to a control system, such as bus overvoltage, overcurrent of a braking unit and the like caused by asynchronous peak value changes of the bus voltage and the braking current, are effectively avoided, and the reliability and the stability of the invention are further improved.

Drawings

FIG. 1 is a schematic diagram of a control system according to the present invention;

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

Detailed Description

As shown in fig. 1, the present invention includes a fast braking control system and a braking method for a three-phase switched reluctance motor.

The brake control system comprises a rectifying unit, a power conversion unit, a control unit and a brake unit, wherein the rectifying unit provides power current required by the control system through a direct current bus;

the rectifying unit is respectively connected with three-phase coils of the three-phase switched reluctance motor through the power conversion unit;

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

the brake unit comprises a brake IGBT module and a brake resistor, the brake IGBT module is connected with the two ends of the rectifying circuit after being connected with the brake resistor in series, and the control end of the brake IGBT module is connected with an IGBT driving circuit;

the control unit comprises a DSP module, a sampling module and other peripheral circuits, the sampling module is respectively connected with the rectifying unit, the power conversion unit, the braking unit and a rotary encoder of the three-phase switch reluctance motor, the sampling module acquires voltage signals and current signals of the control system through a voltage sensor and a current sensor, the sampling module acquires position signals of the three-phase switch 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 acquired by the sampling module.

The brake control method comprises the following steps:

A. the control unit acquires signals of a rotary encoder of the three-phase switch reluctance motor to acquire the relative position of a rotor and a stator;

B. the control unit judges whether a braking signal is received, if the braking signal is not received, the next step is carried out, and if the braking signal is received, the step D is carried out;

C. applying exciting current to an inductance rising area of the three-phase switched reluctance motor, and enabling the three-phase switched reluctance motor to enter an electric operation mode;

the method specifically comprises the following steps: the power unit applies exciting current to an inductance rising area of the three-phase switched reluctance motor to drive the three-phase switched reluctance motor to run electrically, and the current of the rectification unit flows to a motor winding after being modulated by the power IGBT module from the positive pole of the bus and then flows back to the negative pole of the bus of the rectification unit;

D. applying exciting current to an inductance descending area of the three-phase switched reluctance motor, enabling the three-phase switched reluctance motor to enter a power generation operation mode, and rapidly braking the three-phase switched reluctance motor; the specific process is as follows:

d 1: after receiving the braking signal, the power unit applies exciting current to an inductance reduction area of the three-phase switched reluctance motor to enable the three-phase switched reluctance motor to generate electricity and operate, and mechanical energy generated by rotation of a shafting is converted into electric energy;

d 2: the DSP module sends a braking PWM pulse to the braking IGBT driving circuit, the braking IGBT module is conducted, and the braking unit starts to work;

d 3: the power generation current of the three-phase switched reluctance motor flows from one end of the motor winding to the positive pole of the motor bus, flows to the brake resistor through the brake IGBT module, and then flows back to the other end of the motor winding through the negative pole of the bus;

d 4: the electric energy generated by the brake unit is dissipated on the brake resistor in the form of heat;

d 5: in the braking process, the DSP module sends and drives PWM pulses to the power unit through the acquired current information and voltage information, adjusts the generating current of the three-phase switched reluctance motor, realizes the double closed-loop control of the braking current and the bus voltage, balances the generating power and the braking power, and finally realizes the braking effect.

For a better understanding of the present invention, the technical solutions of the present invention are further described below with reference to the accompanying drawings.

As shown in fig. 1, the invention discloses a fast braking control system for a three-phase switched reluctance motor, which comprises a rectifying unit, a power conversion unit, a control unit and a braking unit, wherein the rectifying unit provides power current required by the control system through a direct current bus.

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

The rectifying unit is respectively connected with three-phase coils of the three-phase switch reluctance motor through the power conversion unit.

The power conversion unit comprises three asymmetric half-bridge power circuits, and the three asymmetric half-bridge power circuits are connected with three-phase coils of the three-phase switched reluctance motor in a one-to-one correspondence mode. The asymmetric half-bridge power circuit comprises two power IGBT modules Q which are respectively connected with the wire inlet end and the wire outlet end of a coil corresponding to the three-phase switched reluctance motor in series, the control end of each power IGBT module Q is connected with an IGBT drive circuit, and the IGBT drive circuit adopts an isolation amplifying circuit; a free-wheeling diode D is reversely connected in parallel between the collector and the emitter of each power IGBT module Q, because the two ends of the IGBT can generate extremely high self-induction reverse-phase voltage at the moment of turn-off, the IGBT can be broken down, the self-induction reverse-phase voltage can be short-circuited by the aid of the free-wheeling diode D, and the IGBT can be effectively protected by turning off the forward voltage.

The braking unit comprises a braking IGBT module Q' and a braking resistor R, in the braking process, mechanical energy of the switched reluctance motor is converted into electric energy, and the electric energy generated by braking is converted into heat energy through the braking resistor R to be consumed.

The collector and the emitter of the brake IGBT module Q ' are connected with the brake resistor R in series and then connected with two ends of the direct current bus, the control end of the brake IGBT module Q ' is connected with an IGBT drive circuit, the IGBT drive circuit is used for driving the brake IGBT module Q ' to be switched on and switched off, and the IGBT drive circuit preferably adopts an isolation amplifying circuit; the freewheeling diode D ' is reversely connected in parallel between the collector and the emitter of the braking IGBT module Q ', because the two ends of the IGBT can generate extremely high self-induction reverse-phase voltage at the moment of turn-off, the IGBT can be broken down, the self-induction reverse-phase voltage can be short-circuited by the increase of the freewheeling diode D ', and the forward voltage is equivalently disconnected, so that the IGBT can be effectively protected.

The control unit comprises a DSP module, a sampling module and other peripheral circuits, the sampling module is respectively connected with the rectifying unit, the power conversion unit, the braking unit and a rotary encoder of the three-phase switch reluctance motor, the sampling module acquires voltage signals and current signals of the control system through a voltage sensor and a current sensor, the sampling module acquires position information of a stator and a rotor of the three-phase switch 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 acquired by the sampling module.

The sampling module converts signals generated by the voltage sensor, the current sensor and the rotary encoder into analog quantity signals which can be directly processed by the DSP module, the voltage sensor is connected to two ends of a direct current bus in parallel and used for collecting voltages at two ends of the direct current bus, the current sensor comprises a first current sensor and a second current sensor, the first current sensor is connected with the rectifying circuit and collects current of the direct current bus, and the second current sensor is connected in the braking unit and collects current consumed by the braking resistor in a power generation running state. The sampling module preferably adopts a differential amplification circuit, and the voltage, current and position signals are converted into analog quantity signals which can be directly processed by the DSP module through the differential amplification circuit.

According to the rapid braking control system disclosed by the invention, a braking unit consisting of the braking IGBT module Q' and the braking resistor R is adopted, so that a braking current closed loop is realized in the braking process, meanwhile, the DSP module can adjust the energy generated by the motor and the energy consumed by the resistor to be equal in the braking process, and the switched reluctance motor and a shaft system can reach the maximum braking torque which can be borne on the premise of permission of a hardware circuit of the control system, so that the shortest braking time is reached; the brake resistor R is used as the consumption load of the brake unit, so that the energy generated by the switched reluctance motor in the braking process is consumed on the brake resistor R in the form of heat, and the brake resistor R is provided with a heat dissipation system, so that frequent and repeated braking can be further ensured.

The invention also discloses a control method based on the three-phase switched reluctance motor rapid braking control system, which comprises the following steps:

A. the control unit acquires signals of a rotary encoder of the three-phase switch reluctance motor and acquires the relative position of the rotor and the stator.

B. And D, judging whether the brake signal is received or not by the control unit, if the brake signal is not received, entering the next step, and if the brake signal is received, entering the step D.

C. And applying exciting current to an inductance rising area of the three-phase switched reluctance motor, and enabling the three-phase switched reluctance motor to enter an electric operation mode. The method specifically comprises the following steps:

the power unit applies exciting current to an inductance rising area of the three-phase switched reluctance motor to drive the three-phase switched reluctance motor to run electrically, and the current of the power unit flows to a motor winding after being modulated by a power IGBT module Q from a bus positive pole and then flows back to a bus negative pole of the rectification unit;

D. applying exciting current to an inductance descending area of the three-phase switched reluctance motor, enabling the three-phase switched reluctance motor to enter a power generation operation mode, and rapidly braking the three-phase switched reluctance motor by a braking unit; the specific process is as follows:

d 1: after receiving the braking signal, the rectifying unit applies exciting current to an inductance descending area of the three-phase switched reluctance motor to enable the three-phase switched reluctance motor to generate electricity and operate, and mechanical energy of rotation of a shafting is converted into electric energy;

d 2: the DSP module sends a braking PWM pulse to the braking IGBT driving circuit, the braking IGBT module Q' is conducted, and the braking unit starts to work;

d 3: the generated current of the three-phase switched reluctance motor flows from one end of the motor winding to the positive pole of a motor bus, flows to a brake resistor R through a brake IGBT module Q', and then flows back to the other end of the motor winding through the negative pole of the bus;

d 4: the electrical energy generated by the brake unit is dissipated in the form of heat at the brake resistor R;

d 5: in the braking process, the DSP module sends and drives PWM pulses to the power unit through the acquired current information and voltage information, adjusts the generating current of the three-phase switched reluctance motor, realizes the double closed-loop control of the braking current and the bus voltage, balances the generating power and the braking power, and finally realizes the braking effect.

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

the DSP module collects the generating current of the three-phase switched reluctance motor, the current flowing through a braking load in the braking unit and the voltage at two ends of the rectifying unit;

d 5.2: calculating the power generation power of the motor and the power consumption of the brake resistor;

d 5.3: according to the generated power of the motor and the consumed power of the brake resistor, the DSP module adjusts the duty ratio of the driving PWM pulse through PI operation, and adjusts the generated current of the three-phase switched reluctance motor and the brake current of the brake unit, so that the generated power of the motor and the consumed power of the brake resistor are kept balanced. The method specifically comprises the following steps: if the consumed power of the brake resistor R is larger than the power generated by the motor, reducing the PWM pulse duty ratio of the IGBT module of the brake circuit; and if the consumed power of the brake resistor is less than the power generated by the motor, the PWM pulse duty ratio of the IGBT module of the brake circuit is increased.

It should be noted that how to change the generated current by driving the different power IGBT modules Q to turn on is determined by calculating according to the relationship between the branch current and the final generated current, and the calculation method is a mature technique in the prior art, and therefore is not described herein again.

The larger the generated current is, the larger the braking power is, and the shorter the braking time is, and the purpose of adjusting the braking time is realized by adjusting the generated power and the braking power. The DSP module can also input braking time, and carries out PID regulation control according to the generated current and the speed of the motor rotating speed reduction, so that the motor and the shafting are stopped within a specified time, and the timing braking function is realized.

The rapid braking control method disclosed by the invention realizes rapid braking and frequent braking of the switched reluctance motor, and enables the switched reluctance motor and the shafting to be switched to a braking state from an electric operation state or to be switched to an operation state from braking completion, no mechanical operation is needed, the time is only a few instruction cycles of DSP model operation, the switching time can reach millisecond level, and the braking efficiency of the invention is effectively improved; meanwhile, closed-loop control of the rotating speed and the current is realized in the braking process, the rotating speed and the current signals are synchronously received, the relation among the braking time, the braking current and the rotating speed of the shafting is synchronously adjusted through the DSP module, quick braking is realized, the shafting can be stopped to rotate within the appointed braking time, and the shafting braking device is high in accuracy, reliability and flexibility.

Finally, it should be noted that: the above examples are only intended to illustrate the technical solution of the present invention, but not to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those skilled in the art that various changes, modifications and substitutions can be made therein without departing from the spirit and scope of the embodiments of the present invention.