阅读说明：本技术 一种多电机连接系统及电流滞环控制方法 (Multi-motor connection system and current hysteresis control method ) 是由 张守旭 崔荣鑫 严卫生 王银涛 李俊兵 房新鹏 左磊 林海 于 2020-05-06 设计创作，主要内容包括：本发明公开了一种多电机连接系统及电流滞环控制方法,通过给定参考转速与实际转速的差经过四个PI调节器,得到四个电流值；将四个电流值经过参考电流重构模块得到所需要的参考电流值；将逆变器输出端的电流值经过电流重构模块得到计算电流值；将计算电流值与参考电流值的差值,给到滞环比较器中,生成等幅不等宽的方波信号；将方波信号经过PWM模块,变为驱动IGBT管的开关信号；将PWM信号传输给五相电压源型逆变器模块,五相电压源型逆变器模块控制四直流电机正常工作,实现电机的四象限运行。本发明采用参考电流重构,电流重构以及滞环比较技术,提供了一种新型四直流电机并联控制方法。(The invention discloses a multi-motor connection system and a current hysteresis control method.A difference between a given reference rotating speed and an actual rotating speed passes through four PI regulators to obtain four current values; the four current values pass through a reference current reconstruction module to obtain required reference current values; obtaining a calculated current value by passing the current value of the output end of the inverter through a current reconstruction module; giving the difference value of the calculated current value and the reference current value to a hysteresis comparator to generate square wave signals with equal amplitude and unequal width; the square wave signal is converted into a switching signal for driving an IGBT tube through a PWM module; and transmitting the PWM signal to a five-phase voltage source type inverter module, and controlling the four-direct-current motor to normally work by the five-phase voltage source type inverter module so as to realize the four-quadrant operation of the motor. The invention provides a novel parallel control method for four direct current motors by adopting reference current reconstruction, current reconstruction and hysteresis comparison technologies.)

1. A multi-motor current hysteresis control method is characterized by comprising the following steps:

s1, obtaining four current values through the difference between the given reference rotating speed and the actual rotating speed through four PI regulators;

s2, obtaining the required reference current value by the four current values obtained in the step S1 through a reference current reconstruction module;

s3, obtaining a calculated current value by passing the current value of the output end of the inverter through a current reconstruction module;

s4, giving the difference value of the calculated current value and the reference current value to a hysteresis comparator to generate square wave signals with equal amplitude and unequal width;

s5, converting the square wave signal obtained in the step S4 into a switching signal for driving an IGBT tube through a PWM module;

and S6, transmitting the PWM signal to the five-phase voltage source type inverter module, and controlling the four-direct-current motor to normally work by the five-phase voltage source type inverter module to realize the four-quadrant operation of the motor.

2. The method of claim 1, wherein in step S1, four current values I_mjThe method specifically comprises the following steps:

I_mj＝K_pj(ω_j-ω_jref)+K_ij∫(ω_j-ω_jref)dt

wherein j is 1,2,3,4, K_pjProportional constants of four PI regulators; omega_jThe actual rotating speed of the four direct current motors is obtained; omega_jrefIs the reference speed of the four DC motor, K_ijAre the integration constants of the four PI regulators.

3. The method of claim 1, wherein in step S2, the current value I is referenced_irefThe method specifically comprises the following steps:

wherein, I_m1,I_m2,I_m3,I_m4Four current values respectively.

4. The method of claim 1, wherein in step S3, a current value I is calculated_iThe method specifically comprises the following steps:

wherein, X₁,X₂,X₃,X₄Four detected current values, respectively.

5. The method according to claim 1, wherein in step S4, the output voltage H of the hysteresis comparator_iThe method specifically comprises the following steps:

wherein i is 1,2,3,4,5, U_omIs the amplitude of the voltage applied across the operational amplifier; i is_iref、I_iRespectively a reference current value and a calculated current value; r is a resistance value accessed to the negative input end of an operational amplifier in the hysteresis comparator; u shape₊Is the voltage value of the positive input terminal of the operational amplifier in the hysteresis comparator.

6. A method as claimed in claim 5, characterized in that a positive feedback is introduced between the output and the non-inverting input of the integrated operational amplifier circuit, when the inverting input is supplied with the voltage u_iGradually increases from 0, and u_i≤U₊When the temperature of the water is higher than the set temperature,when u is_i≥U₊When the temperature of the water is higher than the set temperature,

7. Method according to claim 6, characterized in that the upper threshold (trigger) level U is set₊The method specifically comprises the following steps:

lower threshold level U_-The method specifically comprises the following steps:

the return difference voltage Δ U is:

wherein the content of the first and second substances,is the positive supply voltage of the operational amplifier in the hysteresis comparator,is the negative supply voltage, R, of the operational amplifier in the hysteresis comparator₁Is a resistor R fed back from the output end of the operational amplifier to the positive input end of the operational amplifier in the hysteresis comparator₂Is the resistance of the positive input end of an operational amplifier in the hysteresis comparator.

8. The method according to claim 1, wherein in step S5, the ith path voltage H outputted by the hysteresis comparator_i-jThe method specifically comprises the following steps:

wherein i is 1,2,3,4,5, H_iIs the output voltage of the hysteresis comparator;is AND of output of hysteresis comparator_iA complementary voltage; h_i-jThe ith path of voltage output by the hysteresis comparator, j is 1,2, and two paths of PWM signals are generated after passing through the PWM module.

9. A multi-motor connection system characterized by employing the current hysteresis control method of claim 1, comprising:

the rotating speed adjusting module is used for adjusting the difference value between the reference rotating speed and the actual rotating speed;

the current adjusting module is used for adjusting the difference value between the reference current value and the calculated current value;

the hysteresis comparison module is used for converting the difference value of the reference current value and the calculated current value into square waves with equal amplitude and unequal width;

the PWM module is used for converting the square wave output by the hysteresis comparison module into a switching signal to drive the IGBT tube;

and the five-phase voltage source type inverter module drives the four direct current motor to work through the five-phase IGBT tube.

10. The multi-motor connection system according to claim 9, wherein the five-phase voltage source type inverter module includes 10 IGBT tubes divided into 5 groups, T_i,T_i+1One group, will T_iIs connected to the positive electrode of the power supply, and the drain is connected to T_i+1On the source electrode of (1); t is_i+1The drain of each group forms a complete bridge arm, i is 1,2,3,4, 5;

the midpoint of any one group of bridge arms in the five-phase voltage source type inverter module is connected to the negative ends of the four direct current motors, the midpoints of the remaining four groups of bridge arms are sequentially connected to the positive ends of the four direct current motors, and the four direct current motors are connected to the five-phase voltage source type inverter module in parallel.

Technical Field

The invention belongs to the technical field of direct current motor control, and particularly relates to a multi-motor connecting system and a current hysteresis control method.

Background

With the proposal of the national environmental protection concept, the electric automobile industry develops rapidly, and the research on the motor driving system of the electric automobile is numerous at home and abroad, and mainly focuses on two aspects of the application of a novel motor and the improvement of the control strategy of the motor driving system.

At present, electric automobiles mostly adopt direct current brush motors, induction motors, switched reluctance motors and direct current brushless motors. The DC brush motor is controlled by the chopper, has excellent electromagnetic torque control characteristic, simple control and mature technology, and has influenced high-speed performance and operation reliability due to the presence of the brush and the commutator. The induction motor is used as a driving motor of the electric automobile, has low cost, good reliability, wide speed regulation range, mature controller, hot manufacturing technology, small torque fluctuation and low noise, does not need a position sensor but has complex control, and is easily influenced by motor parameters and load change. The switched reluctance motor as a driving motor of an electric automobile has good reliability, low cost, simplicity and large high-speed potential, but has high motor noise and serious torque pulsation, is beneficial and disadvantageous in driving application of the electric automobile, and is less in application of the electric automobile at present. The brushless direct current motor is used as a driving motor of an electric automobile, has compact structure, light weight, high efficiency and good control performance, but has the problems of low reliability under torque pulsation and large current. Because the technology of the direct current motor is mature, most of electric automobiles adopt the direct current motor, and therefore, how to design a novel motor driving system control strategy has practical engineering value.

Disclosure of Invention

The technical problem to be solved by the present invention is to provide a multi-motor connection system and a current hysteresis control method, which are simple in circuit, capable of real-time control, fast in current response speed, and free of carrier, in view of the above-mentioned deficiencies in the prior art.

The invention adopts the following technical scheme:

a multi-motor current hysteresis control method comprises the following steps:

s1, obtaining four current values through the difference between the given reference rotating speed and the actual rotating speed through four PI regulators;

s2, obtaining the required reference current value by the four current values obtained in the step S1 through a reference current reconstruction module;

s3, obtaining a calculated current value by passing the current value of the output end of the inverter through a current reconstruction module;

s4, giving the difference value of the calculated current value and the reference current value to a hysteresis comparator to generate square wave signals with equal amplitude and unequal width;

s5, converting the square wave signal obtained in the step S4 into a switching signal for driving an IGBT tube through a PWM module;

and S6, transmitting the PWM signal to the five-phase voltage source type inverter module, and controlling the four-direct-current motor to normally work by the five-phase voltage source type inverter module to realize the four-quadrant operation of the motor.

Specifically, in step S1, four current values I_mjThe method specifically comprises the following steps:

I_mj＝K_pj(ω_j-ω_jref)+K_ij∫(ω_j-ω_jref)dt

wherein j is 1,2,3,4, K_pjProportional constants of four PI regulators; omega_jThe actual rotating speed of the four direct current motors is obtained; omega_jrefIs the reference speed of the four DC motor, K_ijAre the integration constants of the four PI regulators.

Specifically, in step S2, the current value I is referenced_irefThe method specifically comprises the following steps:

wherein, I_m1,I_m2,I_m3,I_m4Four current values respectively.

In particularIn step S3, a current value I is calculated_iThe method specifically comprises the following steps:

wherein, X₁,X₂,X₃,X₄Four detected current values, respectively.

Specifically, in step S4, the output voltage H of the hysteresis comparator_iThe method specifically comprises the following steps:

wherein i is 1,2,3,4,5, U_omIs the amplitude of the voltage applied across the operational amplifier; i is_iref、I_iRespectively a reference current value and a calculated current value; r is a resistance value accessed to the negative input end of an operational amplifier in the hysteresis comparator; u shape₊Is the voltage value of the positive input terminal of the operational amplifier in the hysteresis comparator.

Furthermore, a positive feedback is introduced between the output end and the non-inverting input end of the integrated operational amplifier circuit, when the inverting input end inputs the voltage u_iGradually increases from 0, and u_i≤U₊When the temperature of the water is higher than the set temperature,

when u is_i≥U₊When the temperature of the water is higher than the set temperature,

the trigger level changes to a lower threshold (trigger) level U_-(ii) a When u is_iIs gradually reduced at u_i＝U₊Formerly, the output voltage u_oIs equal to

Further, the upper threshold (trigger) level U₊The method specifically comprises the following steps:

the lower threshold level U-is specifically:

the return difference voltage Δ U is:

wherein the content of the first and second substances,

is the positive supply voltage of the operational amplifier in the hysteresis comparator,is the negative supply voltage, R, of the operational amplifier in the hysteresis comparator₁Is a resistor R fed back from the output end of the operational amplifier to the positive input end of the operational amplifier in the hysteresis comparator₂Is the resistance of the positive input end of an operational amplifier in the hysteresis comparator.

Specifically, in step S5, the ith path voltage H output by the hysteresis comparator_i-jThe method specifically comprises the following steps:

wherein i is 1,2,3,4,5, H_iIs the output voltage of the hysteresis comparator;is AND of output of hysteresis comparator_iA complementary voltage; h_i-jThe ith path of voltage output by the hysteresis comparator, j is 1,2, and two paths of PWM signals are generated after passing through the PWM module.

Another technical solution of the present invention is a multi-motor connection system, which adopts the current hysteresis control method, including:

the rotating speed adjusting module is used for adjusting the difference value between the reference rotating speed and the actual rotating speed;

the current adjusting module is used for adjusting the difference value between the reference current value and the calculated current value;

the hysteresis comparison module is used for converting the difference value of the reference current value and the calculated current value into square waves with equal amplitude and unequal width;

the PWM module is used for converting the square wave output by the hysteresis comparison module into a switching signal to drive the IGBT tube;

and the five-phase voltage source type inverter module drives the four direct current motor to work through the five-phase IGBT tube.

Specifically, the five-phase voltage source inverter module comprises 10 IGBT tubes which are divided into 5 groups, T_i,T_i+1One group, will T_iIs connected to the positive electrode of the power supply, and the drain is connected to T_i+1On the source electrode of (1); t is_i+1The drain of each group forms a complete bridge arm, i is 1,2,3,4, 5;

the midpoint of any one group of bridge arms in the five-phase voltage source type inverter module is connected to the negative ends of the four direct current motors, the midpoints of the remaining four groups of bridge arms are sequentially connected to the positive ends of the four direct current motors, and the four direct current motors are connected to the five-phase voltage source type inverter module in parallel.

Compared with the prior art, the invention has at least the following beneficial effects:

according to the multi-motor current hysteresis control method, the reference current and the calculated current are calculated in a current reconstruction mode, the original four-phase current is reconstructed into five-phase current, and a switching signal is provided for an IGBT (insulated gate bipolar transistor) tube of a five-phase voltage source type inverter through the hysteresis comparator module and the PWM (pulse width modulation) module, so that the control precision and the stability of the system are improved, the hysteresis comparator module replaces the original triangular carrier module, a hardware circuit is simple, real-time control can be performed, the current response speed is high, and no carrier is needed.

Furthermore, the difference between the reference rotating speed and the actual rotating speed is subjected to PI regulator to form rotating speed closed-loop control, which is beneficial to regulating the rotating speed of the system.

Furthermore, five reference current values are obtained by passing the four current values obtained in the step S1 through a reference current reconstruction module, and current closed-loop control is formed with the calculated current values, which is beneficial to adjusting the system current.

Furthermore, the current value of the output end of the inverter is processed by the current reconstruction module to obtain five calculated current values, and the five calculated current values and the reference current value form current closed-loop control, so that the system current can be favorably regulated.

Furthermore, the difference value of the calculated current and the reference current is sent to a hysteresis comparator to generate square wave signals with equal amplitude and unequal width, a triangular carrier signal is not needed, real-time control can be performed, and the current response speed is high.

Further, the square wave signal obtained in step S4 is converted into a switching signal capable of driving the IGBT tube through the PWM module, and drives the inverter to operate, thereby controlling the normal operation of the motor.

The multi-motor connecting system has four DC motors with negative ends connected to the middle points of one bridge arm of five-phase voltage source inverter and four other bridge arms connected to the positive ends of the four DC motors.

Furthermore, 10 switching signals output by the PWM module are sent to an IGBT tube of the five-phase voltage prototype inverter, and the inverter is driven to work through the switching signals, so that the normal operation of the motor is controlled.

In summary, the invention provides a novel four-dc motor parallel control method by adopting reference current reconstruction, current reconstruction and hysteresis comparison techniques.

The technical solution of the present invention is further described in detail by the accompanying drawings and embodiments.

Drawings

FIG. 1 is a structural diagram of a four-DC motor parallel current hysteresis control system;

fig. 2 is a structural view of a five-phase voltage source inverter;

fig. 3 is a diagram showing a structure of a current hysteresis control circuit, in which (a) is an inverting hysteresis comparator circuit inputted from an inverting input terminal, and (b) is a current hysteresis control circuit.

Detailed Description

In the description of the present invention, it should be noted that, unless otherwise explicitly specified or limited, the terms "mounted," "connected," and "connected" are to be construed broadly, e.g., as meaning either a fixed connection, a removable connection, or an integral connection; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meanings of the above terms in the present invention can be understood in specific cases to those skilled in the art.

Referring to fig. 1, the present invention provides a multi-motor connecting system, including:

a rotating speed adjusting module: the difference between the reference rotational speed and the actual rotational speed is adjusted.

A current regulation module: the difference between the reference current value and the calculated current value is adjusted.

A hysteresis comparison module: and changing the difference value of the current into square waves with equal amplitude and unequal width.

A PWM module: and the square wave output by the hysteresis comparison module is changed into a switching signal capable of driving an IGBT tube.

Five-phase voltage source inverter module: the four direct current motors are driven to normally work through the five-phase IGBT tubes.

The difference value of the reference rotating speed and the actual rotating speed is processed by a rotating speed adjusting module to generate four current values, then the four current values are processed by a reference current reconstruction module to generate five reference current values, the four current values of the output end of the five-phase voltage prototype inverter are arbitrarily selected, the five calculated current values are obtained by a current reconstruction calculating module, the difference between the reference current and the calculated current is sent to a hysteresis loop comparison module to generate five square wave signals with equal amplitude and unequal width, the five square wave signals are converted into 10 switching signals capable of driving the IGBT tubes by a PWM module, then the 10 switching signals are sent to the five-phase voltage prototype inverter module to drive the inverter to work, and further the motor is controlled to work normally.

Referring to fig. 2, a five-phase voltage source inverterComprises 10 IGBT tubes divided into 5 groups T_i,T_i+1One group, will T_iIs connected to the positive electrode of the power supply, and the drain is connected to T_i+1On the source electrode of (1); t is_i+1Is connected to the negative pole of the power supply, each group forms a complete bridge arm, i is 1,2,3,4, 5.

The method comprises the steps that the middle points of any one group of bridge arms in the five-phase voltage source type inverter are connected to the negative ends of four direct current motors, the middle points of the remaining four groups of bridge arms are sequentially connected to the positive ends of the four direct current motors, and the four direct current motors are connected to the inverter in a parallel mode.

Five paths of square wave signals with the same amplitude and different widths output by the hysteresis comparator pass through a PWM module, and each path of square wave signals generates two paths of PWM signals with the same amplitude and opposite directions; two paths of PWM signals of each group are sent to corresponding IGBT tubes to control the inverter to work, so that the motor is controlled to normally run; if T1, T10 are on, DCM1 rotates forward; when T2 and T9 are turned on, DCM1 is inverted; DCM2, DCM3 and DCM4 can be analyzed in the same way, and four-quadrant operation of a four-DC motor can be realized.

The invention discloses a multi-motor current hysteresis control method, which comprises the following steps:

s1, obtaining four current values through the difference between the given reference rotating speed and the actual rotating speed through four PI regulators;

four current values I_mjThe method specifically comprises the following steps:

I_mj＝K_pj(ω_j-ω_jref)+K_ij∫(ω_j-ω_jref)dt

wherein j is 1,2,3,4, K_pjProportional constants of four PI regulators; omega_jThe actual rotating speed of the four direct current motors is obtained; omega_jrefIs the reference speed of the four DC motor, K_ijAre the integration constants of the four PI regulators.

S2, obtaining the required reference current value by the four current values obtained in the step S1 through a reference current reconstruction module;

five reference current values I_irefThe method specifically comprises the following steps:

wherein i is 1,2,3,4, 5;

s3, obtaining a calculated current value by passing the current value of the output end of the inverter through a current reconstruction module;

calculating the current value I_iThe method specifically comprises the following steps:

wherein i is 1,2,3,4, 5; x₁,X₂,X₃,X₄Four detected current values respectively;

s4, giving the difference value of the calculated current value and the reference current value to a hysteresis comparator to generate square wave signals with equal amplitude and unequal width;

output voltage H of hysteresis comparator_iThe method specifically comprises the following steps:

wherein i is 1,2,3,4,5, U_omIs the amplitude of the voltage applied across the operational amplifier; i is_iref、I_iRespectively a reference current value and a calculated current value; r is a resistance value accessed to the negative input end of an operational amplifier in the hysteresis comparator; u shape₊The voltage value of the positive input end of an operational amplifier in the hysteresis comparator is obtained;

referring to fig. 3, the hysteresis comparator circuit has the following structure and working principle:

introducing a positive feedback between the output of the integrated operational amplifier circuit and the non-inverting input of the inverting hysteresis comparator circuit from the inverting input is shown in fig. 3(a), where u is_iFor the reverse-end input voltage, u_oTo output a voltage, U_refIs a reference voltage.

When u is_iGradually increases from 0, and u_i≤U₊When the temperature of the water is higher than the set temperature,

upper threshold (trigger) level U₊The method specifically comprises the following steps:

when u is_i≥U₊When the temperature of the water is higher than the set temperature,

at this time, the trigger level becomes the lower threshold (trigger) level U_-The method specifically comprises the following steps:

when u is_iIs gradually reduced at u_i＝U₊Formerly, the output voltage u_oIs always equal to

Referring to fig. 3(b), the obtained calculated current value and the reference current value are provided to the hysteresis comparator, and the output voltage of the hysteresis comparator is obtained; then the signals are converted into switching signals capable of driving the IGBT tube through the PWM module, and the two paths of PWM signals are generated through the PWM module; and the generated two paths of PWM signals are sent to corresponding IGBT tubes of the inverter to control the on and off of bridge arms of the inverter.

S5, converting the square wave signal obtained in the step S4 into a switching signal capable of driving an IGBT tube through a PWM module;

ith path voltage H output by hysteresis comparator_i-jThe method specifically comprises the following steps:

wherein i is 1,2,3,4,5, H_iIs the output voltage of the hysteresis comparator;

is AND of output of hysteresis comparator_iComplementary to each otherVoltage of (d); h_i-jThe ith path of voltage output by the hysteresis comparator, j is 1,2, and two paths of PWM signals are generated after passing through the PWM module.

And S6, transmitting the PWM signal to the five-phase voltage source type inverter module to enable the inverter to work, controlling the motor to work normally and realizing the four-quadrant operation of the motor.

In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, but not all, embodiments of the present invention. The components of the embodiments of the present invention generally described and illustrated in the figures herein may be arranged and designed in a wide variety of different configurations. Thus, the following detailed description of the embodiments of the present invention, presented in the figures, is not intended to limit the scope of the invention, as claimed, but is merely representative of selected embodiments of the invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

The invention relates to a multi-motor connection system and a current hysteresis control method, which rise rapidly in the electric automobile industry along with the proposal of the national environmental protection concept, and can be completely applied to the field. The control method adopts a PI regulator to regulate the rotating speed, adopts a current reconstruction method to obtain reference current and a calculated current value, adopts a hysteresis control technology to generate square wave signals with equal amplitude and unequal width, replaces an original triangular carrier module with a hysteresis comparison module, has simple hardware circuit, can carry out real-time control, has high current response speed and does not need carrier. The five-phase voltage source inverter is adopted to control the parallel four-direct current motors, and fewer bridge arms are adopted to control the operation of a plurality of motors.

In summary, the invention provides a novel stable four-direct-current motor control method by adopting the technologies of rotating speed regulation, current reconstruction, current regulation and hysteresis comparison, so as to improve the control precision and stability of the system and reduce the energy loss of the system.

The above-mentioned contents are only for illustrating the technical idea of the present invention, and the protection scope of the present invention is not limited thereby, and any modification made on the basis of the technical idea of the present invention falls within the protection scope of the claims of the present invention.