Motor series mode fault-tolerant system and control method
阅读说明：本技术 一种电机串联方式容错系统及控制方法 (Motor series mode fault-tolerant system and control method ) 是由 李伟华 王炜 罗黎明 赵国璋 马义波 董建威 赵宇 于 2020-05-06 设计创作，主要内容包括：本发明一种电机串联方式容错系统及控制方法,对三台直流电机中的故障对象进行组合和分类,并采取对应的容错控制律,每一种故障类型对应一种容错控制律,可以得到处于该故障类型时的最佳容错控制方式,并将三路信号变为四路信号,以便于求出各自的偏差；根据偏差的变化情况来调节滞环控制器的输出,同时,滞环控制器的带宽可以改变功率开关管的通断频率；将滞环控制器输出的方波信号通过PWM转换为高低电平信号,进而控制控制功率开关管的开端,通过滞环控制和PWM将电机的实际转矩控制在给定范围内,避免系统在出现故障时由于转矩或电流过大出现更严重的故障问题；保证电机系统的稳定运行。(The invention relates to a fault-tolerant system and a control method for a motor series connection mode, which are used for combining and classifying fault objects in three direct current motors and adopting corresponding fault-tolerant control laws, wherein each fault type corresponds to one fault-tolerant control law, so that the optimal fault-tolerant control mode in the fault type can be obtained, and three signals are changed into four signals so as to conveniently obtain respective deviation; the output of the hysteresis controller is adjusted according to the variation condition of the deviation, and meanwhile, the bandwidth of the hysteresis controller can change the on-off frequency of the power switch tube; the square wave signal output by the hysteresis controller is converted into a high-low level signal through PWM (pulse-width modulation), so that the starting end of a power switching tube is controlled, the actual torque of the motor is controlled within a given range through the hysteresis control and the PWM, and the problem that the system has more serious faults due to overlarge torque or current when the system has faults is avoided; and the stable operation of the motor system is ensured.)
1. A fault-tolerant control method for a motor series mode is characterized by comprising the following steps:
step 1, setting reference rotating speeds of three direct current motors, acquiring actual rotating speeds of the three direct current motors, acquiring armature currents of the three direct current motors, calculating deviations of the reference rotating speeds and the actual rotating speeds of the three direct current motors respectively, and generating three paths of reference currents through a PI control algorithm;
step 2, detecting the running state of the motor system, judging whether the circuit system has a fault, and if the circuit system has the fault, judging the fault type and the fault position of the motor system;
step 3, adopting a corresponding fault-tolerant control law for the motor system according to the detected fault type, and calculating four reference torques and four feedback torques corresponding to the fault-tolerant control law;
step 4, calculating the deviation of the four reference torques and the four feedback torques, taking the deviation value as the input of the four hysteresis controllers, and outputting four square wave signals;
and 5, converting the four square wave signals output by the four hysteresis controllers into eight level signals which are complementary in pairs through a PWM signal logic generating function, and using the eight level signals as control signals of power switching tubes of the four-bridge-arm fault-tolerant inverter to realize the stable operation of the three-direct-current motor system.
2. The method according to claim 1, wherein in step 2, the fault type F is 0, 1,2,3,4, 5, 6, wherein F is 0, which indicates that three direct current motors are operating normally; f ═ 1 indicates that only motor a failed; f-2 indicates that only motor B failed; f-3 indicates that only motor C failed; f-4 indicates that motor a and motor B are simultaneously malfunctioning; f-5 indicates that motor B and motor C are simultaneously malfunctioning; f-6 indicates that motor a and motor C are malfunctioning at the same time.
3. The method according to claim 1, wherein in step 3, a corresponding fault-tolerant control law is adopted for the motor system according to the detected fault type, and the method comprises the following specific steps:
when only the motor A fails, the fault type of fault-tolerant control is F-1, and a fault-tolerant control system adopts a fault-tolerant control law when the F-1;
when only the motor B fails, the fault type of fault-tolerant control is F-2, and a fault-tolerant control system adopts a fault-tolerant control law when the F-2 is adopted;
when only the motor C fails, the fault type of fault-tolerant control is F & lt3 & gt, and the fault-tolerant control system adopts a fault-tolerant control law when the F & lt3 & gt;
when the motor A and the motor B simultaneously break down, the error type of the fault-tolerant control is F-4, and the fault-tolerant control system adopts a fault-tolerant control law when F-4;
when the motor B and the motor C simultaneously break down, the error type of the fault-tolerant control is F-5, and the fault-tolerant control system adopts a fault-tolerant control law when F-5;
when the motor A and the motor C simultaneously break down, the error type of the fault-tolerant control is F-6, and the fault-tolerant control system adopts a fault-tolerant control law when F-6;
when the motor A, the motor B and the motor C simultaneously break down, all power switch tubes of the four-bridge-arm fault-tolerant inverter are not conducted, and the three direct current motors are all in a stop operation state.
4. The method of claim 3, wherein four reference torques and four feedback torques are calculated for the fault-tolerant control law by:
according to the output of the speed loopChanging the reference torque into four paths of reference torques through a reference torque synthesis algorithm of a fault-tolerant control strategy; armature current I of three DC motors1、I2、I3And the feedback torque synthesis algorithm through the fault-tolerant control strategy is changed into four paths of feedback torques.
5. The method of claim 4,
when F is equal to 0, the first phase is,
when the F is equal to 1, the F is,
when the F is equal to 2, the F is not more than 2,
when the F is 3, the reaction time is as follows,
when the F is equal to 4, the F is not more than 4,
when the F is 5, the reaction time is up to 5,
when the F is equal to 6, the F is not more than 6,
whereinTorque constant, k, of the DC motor corresponding to the reference torque1，k2，k3Is a torque constant of the DC motor corresponding to the feedback torque, andm＝1，2，3。
6. the method of claim 1, wherein in step 4, the deviation between the four reference torques and the four feedback torques is calculated by:
the deviation value is used as the input of a four-way hysteresis controller, and four-way square wave signals are output, and the specific method comprises the following steps:
let uiIs the input of a four-way hysteresis controller, and i is equal to 1,2,3,4,is the upper threshold limit of the hysteresis controller input,lower threshold, u, for the hysteresis controller inputmaxIs the upper limit of the output of the hysteresis controller, uminFor the lower output limit of the hysteretic controller, the logic generating function of the hysteretic controller is as follows:
where P represents the output of the hysteretic controller from the last comparison.
7. The method according to claim 1, wherein in step 5, the four square wave signals output by the four hysteretic-loop controller are changed into eight level signals which are complementary to each other, and the eight level signals are used as control signals of a power switch tube of the four-leg fault-tolerant inverter, and the method specifically comprises the following steps:
firstly, the output of the four-way hysteresis controller is processed by a PWM signal logic generating function to generate four-way level signals, specifically:
q is 1, Q is 0, and represents PWM output high level and low level respectively, and high level is defined as active level, and then control power switch tube to conduct, and low level is inactive level, and control power switch tube to break, then Zi＝Z1，Z2，Z3，Z4The PWM logic generation function of (a) is:
secondly, four paths of level signals output by the PWM logic generating function are processed by the main controller to obtain eight paths of level signals which are complementary in pairs, namely Z11、Z12、Z21、Z22、Z31、Z32、Z41、Z42；
Finally, Z is11、Z12The signals are respectively input to the gates of the a bridge arm S1 and S5; will Z21、Z22The grid voltages are respectively input to the grids of the b bridge arms S2 and S6; will Z31、Z32The grid voltages are respectively input to the grids of the c bridge arms S3 and S7; will Z41、Z42The signals are input to the gates of d-bridge arms S4 and S8, respectively.
8. A fault-tolerant system of a motor series connection mode, which is characterized in that the fault-tolerant control method of any one of claims 1 to 7 is adopted, and the fault-tolerant system comprises four bridge arm fault-tolerant inverters, three direct current motors, a main controller and a power supply source, wherein the direct current motors are provided with three direct current motors, the three direct current motors are connected in series, and the three direct current motors are all electrically connected with the four bridge arm fault-tolerant inverters; the three direct current motors are all connected with a main controller, and meanwhile, the main controller is connected with the four-bridge-arm fault-tolerant inverter.
9. The system of claim 8, wherein the four leg fault tolerant inverter comprises power switching tubes, triacs, fast fuses, and DC power DC, wherein eight power switching tubes are provided, each power switching tube being a power switching tube S1、S2、S3、S4、S5、S6、S7And S8(ii) a The bidirectional thyristors are four in number, and are respectively bidirectional thyristors TR1、TR2、TR3And TR4(ii) a The eight fast fusing wires are respectively fast fusing wires F1、F2、F3、F4、F5、F6、F7And F8(ii) a One direct current power supply DC is arranged; specifically, the method comprises the following steps:
power switch tube S1、S2、S3And S4Respectively with a fast fuse F1Quick fuse F2Quick fuse F3And a fast fuse F4Connecting, quick-fusing filaments F1Quick fuse F2Quick fuse F3And a fast fuse F4The common terminal of the power supply is connected with the positive pole of the power supply DC;
power switch tube S5Power switch tube S6Power switch tube S7And a power switch tube S8Respectively with a fast fuse F5Quick fuse F6Quick fuse F7And a fast fuse F8Connecting, quick-fusing filaments F5Quick fuse F6Quick fuse F7And a fast fuse F8The common terminal of the power supply is connected with the DC cathode of the power supply;
power switch tube S1Drain electrode of (1) and power switch tube S5All sources of the transistors are connected with the bidirectional thyristor TR1Is connected with one end of the connecting rod; power switch tube S2Drain electrode of (1) and power switch tube S6All sources of the transistors are connected with the bidirectional thyristor TR2Is connected with one end of the connecting rod; power switch tube S3Drain electrode of (1) and power switch tube S7All sources of the transistors are connected with the bidirectional thyristor TR3One end of the power switch tube S is connected with the power switch tube S4Drain electrode of (1) and power switch tube S8All sources of the transistors are connected with the bidirectional thyristor TR4Is connected with one end of the connecting rod;
wherein, the three direct current motors are respectively a first direct current motor (A), a second direct current motor (B) and a third direct current motor (C), the positive pole of the first direct current motor (A) and the bidirectional thyristor TR1Is connected with the other end of the first direct current motor (A), the negative pole of the first direct current motor (A) and the positive pole of the second direct current motor (B) are both connected with the bidirectional thyristor TR2The negative pole of the second direct current motor (B) and the positive pole of the third direct current motor (C) are connected with the bidirectional thyristor TR3Is connected with the other end of the third direct current motor (C), the negative pole of the third direct current motor (C) is connected with the bidirectional thyristor TR4And the other end of the two are connected.
10. The system according to claim 8, wherein the master controller comprises a fault-tolerant control strategy module, a hysteresis controller, a PWM signal logic generating function module and a master control unit, wherein the hysteresis controller is loaded with the logic generating module, the fault-tolerant control strategy module is used for generating a fault-tolerant control law of the motor system, then generating four-way reference torque and four-way feedback torque through the fault-tolerant control law, calculating the deviation between the four-way reference torque and the four-way feedback torque, and then taking the deviation as the input of the hysteresis controller; the hysteresis controller is used for generating a PWM output signal of the hysteresis controller according to the received deviation value and transmitting the output value to the PWM signal logic generating function module; the PWM signal logic generation function module is used for generating four paths of level signals from the received PWM output signals; the main control unit is used for generating eight paths of pairwise complementary level signals from the four paths of received level signals.
Technical Field
The invention belongs to the technical field of multi-motor control, and particularly relates to a motor series fault-tolerant system and a control method.
Background
In recent years, the control and driving technology of multiple direct current motors has become an important research field, and can complete complex work which cannot be completed by a plurality of single direct current motors, with the improvement of the control technology of multiple direct current motors by various enterprises and the development of power electronic technology and digital control technology, the fault detection, diagnosis, fault processing and fault-tolerant control of a motor system are made into a hot research content, the fault-tolerant control technology can be mainly divided into two types, namely passive fault-tolerant control and active fault-tolerant control, the passive fault-tolerant control is mainly realized by improving the anti-interference performance of the system, and the active fault-tolerant control is realized by adjusting the structure and parameters of a controller. Compared with a brushless direct current motor and a permanent magnet synchronous motor, the fault-tolerant control technology of the multi-direct current motor is less, but with continuous innovation of the control and driving technology of the multi-direct current motor, the advantages of the direct current motor are gradually shown, and a plurality of students begin to research a multi-direct current motor system. At present, faults of a multi-direct current motor system are mainly divided into two categories, namely inverter faults and motor faults, when the multi-direct current motor system breaks down, in order to avoid sudden stop or instability of the system, the system needs to be ensured to have certain fault-tolerant performance, and robustness of the system is improved, so that a fault-tolerant control technology becomes very important.
Disclosure of Invention
The invention aims to provide a motor series connection mode fault-tolerant system and a motor series connection mode fault-tolerant method, which are used for solving the problem of how to improve the fault-tolerant performance of a multi-direct current motor system.
In order to achieve the purpose, the invention adopts the technical scheme that:
the invention provides a fault-tolerant control method for a motor series connection mode, which comprises the following steps of:
step 1, setting reference rotating speeds of three direct current motors, acquiring actual rotating speeds of the three direct current motors, acquiring armature currents of the three direct current motors, calculating deviations of the reference rotating speeds and the actual rotating speeds of the three direct current motors respectively, and generating three paths of reference currents through a PI control algorithm;
step 2, detecting the running state of the motor system, judging whether the circuit system has a fault, and if the circuit system has the fault, judging the fault type and the fault position of the motor system;
step 3, adopting a corresponding fault-tolerant control law for the motor system according to the detected fault type, and calculating four reference torques and four feedback torques corresponding to the fault-tolerant control law;
step 4, calculating the deviation of the four reference torques and the four feedback torques, taking the deviation value as the input of the four hysteresis controllers, and outputting four square wave signals;
and 5, converting the four square wave signals output by the four hysteresis controllers into eight level signals which are complementary in pairs through a PWM signal logic generating function, and using the eight level signals as control signals of power switching tubes of the four-bridge-arm fault-tolerant inverter to realize the stable operation of the three-direct-current motor system.
Preferably, in step 2, the fault type F is 0, 1,2,3,4, 5, 6, where F is 0, which indicates that three dc motors are operating normally; f ═ 1 indicates that only motor a failed; f-2 indicates that only motor B failed; f-3 indicates that only motor C failed; f-4 indicates that motor a and motor B are simultaneously malfunctioning; f-5 indicates that motor B and motor C are simultaneously malfunctioning; f-6 indicates that motor a and motor C are malfunctioning at the same time.
Preferably, in step 3, a corresponding fault-tolerant control law is adopted for the motor system according to the detected fault type, and the specific method is as follows:
when only the motor A fails, the fault type of fault-tolerant control is F-1, and a fault-tolerant control system adopts a fault-tolerant control law when the F-1;
when only the motor B fails, the fault type of fault-tolerant control is F-2, and a fault-tolerant control system adopts a fault-tolerant control law when the F-2 is adopted;
when only the motor C fails, the fault type of fault-tolerant control is F & lt3 & gt, and the fault-tolerant control system adopts a fault-tolerant control law when the F & lt3 & gt;
when the motor A and the motor B simultaneously break down, the error type of the fault-tolerant control is F-4, and the fault-tolerant control system adopts a fault-tolerant control law when F-4;
when the motor B and the motor C simultaneously break down, the error type of the fault-tolerant control is F-5, and the fault-tolerant control system adopts a fault-tolerant control law when F-5;
when the motor A and the motor C simultaneously break down, the error type of the fault-tolerant control is F-6, and the fault-tolerant control system adopts a fault-tolerant control law when F-6;
when the motor A, the motor B and the motor C simultaneously break down, all power switch tubes of the four-bridge-arm fault-tolerant inverter are not conducted, and the three direct current motors are all in a stop operation state.
Preferably, four reference torques and four feedback torques corresponding to the fault-tolerant control law are calculated, and the specific method is as follows:
according to the output of the speed loopChanging the reference torque into four paths of reference torques through a reference torque synthesis algorithm of a fault-tolerant control strategy; armature current I of three DC motors1、I2、I3And the feedback torque synthesis algorithm through the fault-tolerant control strategy is changed into four paths of feedback torques.
Preferably, when F is 0,
when the F is equal to 1, the F is,
when the F is equal to 2, the F is not more than 2,
when the F is 3, the reaction time is as follows,
when the F is equal to 4, the F is not more than 4,
when the F is 5, the reaction time is up to 5,
when the F is equal to 6, the F is not more than 6,
whereinTorque constant, k, of the DC motor corresponding to the reference torque1，k2，k3Is a torque constant of the DC motor corresponding to the feedback torque, and
preferably, in step 4, the deviation between the four reference torques and the four feedback torques is calculated by the following specific method:
the deviation value is used as the input of a four-way hysteresis controller, and four-way square wave signals are output, and the specific method comprises the following steps:
let uiIs the input of a four-way hysteresis controller, and i is equal to 1,2,3,4,is the upper threshold limit of the hysteresis controller input,lower threshold, u, for the hysteresis controller inputmaxIs the upper limit of the output of the hysteresis controller, uminFor the lower output limit of the hysteretic controller, the logic generating function of the hysteretic controller is as follows:
where P represents the output of the hysteretic controller from the last comparison.
Preferably, in step 5, the four square wave signals output by the four hysteresis controllers are changed into eight level signals which are complementary to each other in pairs, and the eight level signals are used as control signals of the power switching tubes of the four-leg fault-tolerant inverter, and the specific method is as follows:
firstly, the output of the four-way hysteresis controller is processed by a PWM signal logic generating function to generate four-way level signals, specifically:
q is 1, Q is 0, and represents PWM output high level and low level respectively, and high level is defined as active level, and then control power switch tube to conduct, and low level is inactive level, and control power switch tube to break, then Zi＝Z1，Z2，Z3，Z4The PWM logic generation function of (a) is:
secondly, four paths of level signals output by the PWM logic generating function are processed by the main controller to obtain eight paths of level signals which are complementary in pairs, namely Z11、Z12、Z21、Z22、Z31、Z32、Z41、Z42；
Finally, Z is11、Z12The signals are respectively input to the gates of the a bridge arm S1 and S5; will Z21、Z22The grid voltages are respectively input to the grids of the b bridge arms S2 and S6; will Z31、Z32The grid voltages are respectively input to the grids of the c bridge arms S3 and S7; will Z41、Z42The signals are input to the gates of d-bridge arms S4 and S8, respectively.
A fault-tolerant system of a motor series mode adopts the fault-tolerant control method, and comprises four bridge arm fault-tolerant inverters, three direct current motors, a main controller and a power supply, wherein the direct current motors are connected in series, and are all electrically connected with the four bridge arm fault-tolerant inverters; the three direct current motors are all connected with a main controller, and meanwhile, the main controller is connected with the four-bridge-arm fault-tolerant inverter.
Preferably, the four-leg fault-tolerant inverter comprises eight power switching tubes, eight bidirectional thyristors, eight fast fuses and a direct-current power supply DC, wherein the eight power switching tubes are respectively a power switching tube S1Power switch tube S2Power switch tube
S3Power switch tube S4Power switch tube S5Power switch tube S6Power switch tube S7And a power switch tube S8(ii) a The bidirectional thyristors are four in number, and are respectively bidirectional thyristors TR1、TR2、TR3And TR4(ii) a The eight fast fusing wires are respectively fast fusing wires F1、F2、F3、F4、F5、F6、F7And F8(ii) a One direct current power supply DC is arranged; specifically, the method comprises the following steps:
power switch tube S1、S2、S3And S4Respectively with a fast fuse F1Quick fuse F2Quick fuse F3And a fast fuse F4Connecting, quick-fusing filaments F1Quick fuse F2Quick fuse F3And a fast fuse F4The common terminal of the power supply is connected with the positive pole of the power supply DC;
power switch tube S5Power switch tube S6Power switch tube S7And a power switch tube S8Respectively with a fast fuse F5Quick fuse F6Quick fuse F7And a fast fuse F8Connecting, quick-fusing filaments F5Quick fuse F6Quick fuse F7And a fast fuse F8The common terminal of the power supply is connected with the DC cathode of the power supply;
power switch tube S1Drain electrode of (1) and power switch tube S5All sources of the transistors are connected with the bidirectional thyristor TR1Is connected with one end of the connecting rod; power switch tube S2Drain electrode of (1) and power switch tube S6All sources of the transistors are connected with the bidirectional thyristor TR2Is connected with one end of the connecting rod; power switch tube S3Drain electrode of (1) and power switch tube S7All sources of the transistors are connected with the bidirectional thyristor TR3One end of the power switch tube S is connected with the power switch tube S4Drain electrode of (1) and power switch tube S8All sources of the transistors are connected with the bidirectional thyristor TR4Is connected with one end of the connecting rod;
wherein, the three direct current motors are respectively a first direct current motor, a second direct current motor and a third direct current motor, the positive pole of the first direct current motor and the bidirectional thyristor TR1Is connected at the other end thereof to a first direct currentThe cathode of the motor and the anode of the second direct current motor are both connected with the bidirectional thyristor TR2The negative pole of the second direct current motor and the positive pole of the third direct current motor are connected with the bidirectional thyristor TR3Is connected with the other end of the third direct current motor, and the negative pole of the third direct current motor is connected with the bidirectional thyristor TR4And the other end of the two are connected.
Preferably, the main controller comprises a fault-tolerant control strategy module, a hysteresis controller, a PWM signal logic generation function module and a main control unit, wherein the hysteresis controller is loaded with the logic generation module, the fault-tolerant control strategy module is used for generating a fault-tolerant control law of the motor system, then generating four reference torques and four feedback torques according to the fault-tolerant control law, calculating a deviation between the four reference torques and the four feedback torques, and then taking the deviation as an input of the hysteresis controller; the hysteresis controller is used for generating a PWM output signal of the hysteresis controller according to the received deviation value and transmitting the output value to the PWM signal logic generating function module; the PWM signal logic generation function module is used for generating four paths of level signals from the received PWM output signals; the main control unit is used for generating eight paths of pairwise complementary level signals from the four paths of received level signals.
Compared with the prior art, the invention has at least the following beneficial effects:
the fault-tolerant control method for the motor series connection mode can enable the system to have certain fault-tolerant control capability when a certain direct current motor fails, and ensures the stable operation of the system; combining and classifying fault objects in the three direct current motors, adopting corresponding fault-tolerant control laws, wherein each fault type corresponds to one fault-tolerant control law, obtaining the optimal fault-tolerant control mode when the fault type exists, and changing three signals into four signals so as to conveniently obtain respective deviation; adjusting the output of the hysteresis controller according to the variation condition of the deviation, wherein the output positive value indicates that the torque needs to be increased, and the output negative value indicates that the torque needs to be reduced, so that the feedback torque fluctuates in the upper and lower ranges of the reference torque, and meanwhile, the bandwidth of the hysteresis controller can change the on-off frequency of the power switch tube; the square wave signal output by the hysteresis controller is converted into a high-low level signal through PWM (pulse width modulation), namely, a positive value is output to be converted into a high level, a negative value is output to be converted into a low level, the high level is an effective level, the conduction of a power switch tube is controlled, the low level is an ineffective level, the turn-off of the power switch tube is controlled, the actual torque of a motor is controlled within a given range through hysteresis control and PWM, and the problem that the system has more serious faults due to overlarge torque or current when the system has faults is avoided.
Furthermore, four reference torques corresponding to the fault-tolerant control law are used as target values of hysteresis control, and four feedback torques are used as actual values of hysteresis control, so that the actual values are changed following the target values.
The fault-tolerant system of the motor series connection mode can enable the system to have certain fault-tolerant control capability when a certain direct current motor fails, and can control the rotating speed and the torque of three direct current motors and follow the change of a reference value.
In summary, the present invention provides a control system and a control method for a fault-tolerant system in a motor series connection manner, which provides a fault-tolerant control strategy when any one or two of three dc motors fail, and ensures stable operation of a motor system.
Drawings
FIG. 1 is a circuit diagram of a four leg fault tolerant inverter of the present invention;
FIG. 2 is a flow chart illustrating a control method according to the present invention;
FIG. 3 is a schematic diagram of a control system according to the present invention.
Detailed Description
The present invention will be described in further detail with reference to the accompanying drawings.
Referring to fig. 3, the fault-tolerant system of a series connection mode of motors provided by the present invention includes a four-leg fault-tolerant inverter, three dc motors, a main controller and a power supply, wherein the three dc motors are connected in series, and are all electrically connected to the four-leg fault-tolerant inverter; the three direct current motors are all connected with a main controller, and meanwhile, the main controller is connected with the four-bridge-arm fault-tolerant inverter.
The main controller is used for collecting the running state information of the three direct current motors and carrying out internal processing according to the detected running state information, and the internal processing comprises the functions of motor rotating speed reading, sampling current processing, fault-tolerant control strategy, PID control algorithm, hysteresis control algorithm, PWM output and the like, wherein the output eight-path level signals are used for controlling the on and off of eight power switch tubes of the four-bridge-arm fault-tolerant inverter, so that the midpoint voltage of four bridge arms is changed, the rotating speed and the torque of the three direct current motors are further controlled, and the starting and stopping of the three direct current motors are controlled.
The three direct current motors are respectively a first direct current motor A, a second direct current motor B and a third direct current motor C.
The main controller comprises a fault-tolerant control strategy module, a hysteresis controller, a PWM signal logic generation function module and a main control unit, wherein the hysteresis controller is loaded with the logic generation module, the fault-tolerant control strategy module is used for generating a fault-tolerant control law of the motor system, the fault-tolerant control law comprises a reference torque synthesis algorithm and a feedback torque synthesis algorithm, four paths of reference torques and four paths of feedback torques are generated through the fault-tolerant control law, the deviation between the four paths of reference torques and the four paths of feedback torques is calculated, and the deviation is used as the input of the hysteresis controller; the logic generation module in the hysteresis controller is used for generating a PWM output signal of the hysteresis controller according to the received deviation value and transmitting the output value to the PWM signal logic generation function module; the PWM signal logic generation function module is used for generating four paths of level signals from the received PWM output signals; the main control unit is used for generating eight paths of pairwise complementary level signals from the four paths of received level signals.
Referring to fig. 1, the four-leg fault-tolerant inverter includes eight power switching tubes, eight bidirectional thyristors, fast fuses, and a DC power supply DC, where the number of the power switching tubes is S1Power switch tube S2Power switch tube S3Power switch tube S4Power switch tube S5Power switch tube S6Power switch tube S7And a power switch tube S8(ii) a The bidirectional thyristors are four, and are bidirectional crystal respectivelyBrake pipe TR1、TR2、TR3And TR4(ii) a The eight fast fusing wires are respectively fast fusing wires F1、F2、F3、F4、F5、F6、F7And F8(ii) a One direct current power supply DC is arranged; specifically, the method comprises the following steps:
power switch tube S1、S2、S3And S4Respectively with a fast fuse F1Quick fuse F2Quick fuse F3And a fast fuse F4Connecting, quick-fusing filaments F1Quick fuse F2Quick fuse F3And a fast fuse F4The common terminal of the power supply is connected with the positive pole of the power supply DC;
power switch tube S5Power switch tube S6Power switch tube S7And a power switch tube S8Respectively with a fast fuse F5Quick fuse F6Quick fuse F7And a fast fuse F8Connecting, quick-fusing filaments F5Quick fuse F6Quick fuse F7And a fast fuse F8The common terminal of the power supply is connected with the DC cathode of the power supply;
power switch tube S1Drain electrode of (1) and power switch tube S5All sources of the transistors are connected with the bidirectional thyristor TR1Is connected with one end of the connecting rod; power switch tube S2Drain electrode of (1) and power switch tube S6All sources of the transistors are connected with the bidirectional thyristor TR2Is connected with one end of the connecting rod; power switch tube S3Drain electrode of (1) and power switch tube S7All sources of the transistors are connected with the bidirectional thyristor TR3One end of the power switch tube S is connected with the power switch tube S4Drain electrode of (1) and power switch tube S8All sources of the transistors are connected with the bidirectional thyristor TR4Is connected with one end of the connecting rod;
the first direct current motor A, the second direct current motor B and the third direct current motor C adopt a connection mode of end-to-end series connection, namely the anode of the first direct current motor A and the bidirectional thyristor TR1Is connected with the other end of the first direct current motor A, the negative pole of the first direct current motor A and the positive pole of the second direct current motor B are both connected with the bidirectional thyristor TR2Is connected with the other end of the first direct current motor B, the negative pole of the second direct current motor B and the positive pole of the third direct current motor C are both connected with the bidirectional thyristor TR3Is connected with the other end of the third direct current motor C, the negative pole of the third direct current motor C is connected with the bidirectional thyristor TR4And the other end of the two are connected.
The system software comprises a fault-tolerant control strategy, a hysteresis controller and a logic generating function thereof, and a PWM signal logic generating function.
Referring to fig. 2, the fault-tolerant control method for a series connection of motors provided by the present invention includes the following steps:
step 1, initializing a direct current motor system; setting three DC motor reference rotating speedObtaining the actual rotating speed omega of three direct current motors1、ω2、ω3Obtaining armature currents I of three direct current motors1、I2、I3Respectively calculating the deviation between the reference rotating speed and the actual rotating speed of the three direct current motors, and generating three reference currents through a PI control algorithm
Step 2, detecting which motor of the three direct current motors fails through the existing fault detection technology, and dividing the motor into different fault types according to the difference of the failed motors;
step 3, adopting the most appropriate fault-tolerant control law, namely the control law of the fault-tolerant control strategy, to the motor system according to the detected fault type to generate four reference torques and four feedback torques, wherein the four reference torques are respectively the reference torques Tref1Reference torque Tref2Reference torque Tref3And a reference torque Tref4(ii) a The four feedback torques are respectively feedback torque Tfb1Feedback torque Tfb2Feedback torque Tfb3And feedback torque Tfb4；
Step 4, calculating four-way reference torque Tref1、Tref2、Tref、Tref4And four feedback torques Tfb1、Tfb2、Tfb3、Tfb4And the deviation value is used as the input of the four-way hysteresis controller, and four-way square wave signals Z are output1，Z2，Z3，Z4；
Step 5, outputting the four paths of square wave signals Z output by the four paths of hysteresis controllers through a PWM signal logic generating function1，Z2，Z3，Z4The eight paths of level signals which are complementary to each other are changed into eight paths of level signals which are used as control signals of power switching tubes of the four-bridge-arm fault-tolerant inverter, and therefore stable operation of a three-direct-current motor system is achieved.
Referring to fig. 3, a fault-tolerant control strategy is added to a current and torque double closed-loop control structure of a motor series fault-tolerant system, and the fault-tolerant control strategy of the motor series fault-tolerant system is only suitable for a direct current motor fault, when a fault other than the direct current motor fault occurs, a fast fuse and a bidirectional thyristor of a four-leg fault-tolerant inverter can play a role of protecting a circuit, so that the four-leg fault-tolerant inverter or the direct current motor is prevented from being damaged due to the fault other than the fault-tolerant control strategy.
The fault type of the system possibly occurring on the DC motor side is analyzed, suitable fault-tolerant control laws required when the system has a certain fault are respectively calculated, each fault-tolerant control law comprises a reference torque synthesis algorithm and a feedback torque synthesis algorithm, all the fault-tolerant control laws are stored in the STM32 main controller, and once the system has a fault in the operation process, the most suitable fault-tolerant control law is selected according to the fault type.
In step 2, the fault type of the motor system is specifically as follows:
the failure type F is 0, 1,2,3,4, 5, and 6, where F is 0 to indicate that three dc motors are normally operated, F is 1 to indicate that only motor a fails, F is 2 to indicate that only motor B fails, F is 3 to indicate that only motor C fails, F is 4 to indicate that motor a and motor B fail simultaneously, F is 5 to indicate that motor B and motor C fail simultaneously, and F is 6 to indicate that motor a and motor C fail simultaneously, and when motors a, B, and C fail simultaneously, the driving system stops operating completely, that is, fault-tolerant control is not required.
All cases of direct current motor failure and control strategies adopted are as follows:
when only the motor A fails, the fault type of fault-tolerant control is F-1, and a fault-tolerant control system adopts a fault-tolerant control law when the F-1;
when only the motor B fails, the fault type of fault-tolerant control is F-2, and a fault-tolerant control system adopts a fault-tolerant control law when the F-2 is adopted;
when only the motor C fails, the fault type of fault-tolerant control is F & lt3 & gt, and the fault-tolerant control system adopts a fault-tolerant control law when the F & lt3 & gt;
when the motor A and the motor B simultaneously break down, the error type of the fault-tolerant control is F-4, and the fault-tolerant control system adopts a fault-tolerant control law when F-4;
when the motor B and the motor C simultaneously break down, the error type of the fault-tolerant control is F-5, and the fault-tolerant control system adopts a fault-tolerant control law when F-5;
when the motor A and the motor C simultaneously break down, the error type of the fault-tolerant control is F-6, and the fault-tolerant control system adopts a fault-tolerant control law when F-6;
when the motor A, the motor B and the motor C simultaneously break down, all power switch tubes of the four-bridge-arm fault-tolerant inverter are not conducted, and the three direct current motors are all in a stop operation state.
In step 3, the fault-tolerant control law corresponding to each fault of the motor system is specifically as follows:
according to the output of the speed loopReference torque synthesis algorithm through fault-tolerant control strategy to become four-way reference torque Tref1、Tref2、Tref、Tre(ii) a Armature current I of three DC motors1、I2、I3By fault-tolerant controlThe feedback torque synthesis algorithm of the control strategy is changed into four-way feedback torque Tfb1、Tfb、Tfb3、Tfb。
The specific reference torque synthesis algorithm and the feedback torque synthesis algorithm are as follows:
combined with the output of the speed loopAnd armature currents I of three direct current motors1、I2、I3Adopting a corresponding reference torque synthesis algorithm and a corresponding feedback torque synthesis algorithm according to the type of the system fault, wherein the four-way reference torque is Tref1、Tref2、Tref3、Tref4The four feedback torques are Tfb1、Tfb2、Tfb3、Tfb4The specific method comprises the following steps:
when F is equal to 0, the first phase is,
when the F is equal to 1, the F is,
when the F is equal to 2, the F is not more than 2,
when the F is 3, the reaction time is as follows,
when the F is equal to 4, the F is not more than 4,
when the F is 5, the reaction time is up to 5,
when the F is equal to 6, the F is not more than 6,
whereinTorque constant, k, of the DC motor corresponding to the reference torque1，k2，k3Is a torque constant of the DC motor corresponding to the feedback torque, and
the deviation formula of the four-way reference torque and the four-way feedback torque is as follows:
let uiIs the input of a four-way hysteresis controller, and i is equal to 1,2,3,4,is the upper threshold limit of the hysteresis controller input,lower threshold, u, for the hysteresis controller inputmaxIs the upper limit of the output of the hysteresis controller, uminFor the lower output limit of the hysteretic controller, the logic generating function of the hysteretic controller is as follows:
where P represents the output of the hysteretic controller from the last comparison.
Firstly, the output of the four-path hysteresis controller generates four-path level signals through a PWM signal logic generating function, and the specific method and the corresponding relation are as follows:
q is 1, Q is 0, and represents PWM output high level and low level respectively, and high level is defined as active level, and then control power switch tube to conduct, and low level is inactive level, and control power switch tube to break, then Zi＝Z1，Z2，Z3，Z4The PWM logic generation function of (a) is:
secondly, after four paths of logic signals obtained according to the PWM logic generating function are processed by a main control unit with the model of STM32, each path of logic signals respectively outputs two paths of complementary level signals, and eight paths of level signals are respectively Z11、Z12、Z21、Z22、Z31、Z32、Z41、Z42。
Finally, Z is11、Z12The signals are respectively input to the gates of the a bridge arm S1 and S5; will Z21、Z22The grid voltages are respectively input to the grids of the b bridge arms S2 and S6; will Z31、Z32The grid voltages are respectively input to the grids of the c bridge arms S3 and S7; will Z41、Z42The signals are input to the gates of d-bridge arms S4 and S8, respectively.
The invention can be applied to traction motor systems of large-scale mechanical equipment, such as oil rigs, rolling mills, mining machines and the like, and has the advantages of large traction force, stable operation, simple control structure, high efficiency, energy conservation and the like.
In conclusion, the invention can enable the three-DC motor driving system of the four-leg fault-tolerant inverter to have certain fault-tolerant control capability when a motor fault occurs, can realize independent four-quadrant operation of the three-DC motor in a series connection mode, and can improve the stability and response speed of the control system.
The above description is only illustrative of the preferred embodiments of the present invention, and any structural changes, improvements, modifications, etc. made without departing from the principle of the present invention are deemed to be within the scope of the present invention.