阅读说明：本技术 一种开关磁阻电机控制方法 (Control method of switched reluctance motor ) 是由 张亚楠 李龙春 文佳慧 滑军杰 郭瑞峰 于 2021-09-01 设计创作，主要内容包括：本申请属于航空电机控制技术领域,特别涉及一种开关磁阻电机控制方法,包括：当电机转子的位置角度处于第一相导通区间时,自第二相结束时刻,对第一相PWM调制波形的下降沿从0计数；当检测到上升沿时,第一相的上、下功率开关管输出高电平；当检测到下降沿时,若计数为奇数,则第一相的上功率开关管输出高电平,第二相的上功率开关管输出低电平；若计数为偶数,则第一相的上功率开关管输出低电平,第二相的上功率开关管输出高电平；当电机转子的位置角度处于第一相导通区间外时,第一相的上、下功率开关管输出低电平。本申请降低了功率二极管的过载电流,提高了功率二极管的使用寿命,增加了开关磁阻起动/发电系统工作的可靠性。(The application belongs to the technical field of aviation motor control, and particularly relates to a control method of a switched reluctance motor, which comprises the following steps: when the position angle of the motor rotor is in a first phase conduction interval, counting the falling edge of the first phase PWM modulation waveform from 0 from the second phase end time; when the rising edge is detected, the upper power switch tube and the lower power switch tube of the first phase output high levels; when a falling edge is detected, if the count is odd, the upper power switch tube of the first phase outputs a high level, and the upper power switch tube of the second phase outputs a low level; if the count is even, the upper power switch tube of the first phase outputs low level, and the upper power switch tube of the second phase outputs high level; when the position angle of the motor rotor is outside the first phase conduction interval, the upper power switch tube and the lower power switch tube of the first phase output low levels. The application reduces the overload current of the power diode, prolongs the service life of the power diode, and increases the working reliability of the switched reluctance starting/generating system.)

1. A control method of a switched reluctance motor, the switched reluctance motor comprises a phase A, a phase B, a phase C of a three-phase asymmetric half-bridge circuit, a starting input capacitor C1, a generated voltage output capacitor C2 and an excitation diode D3, wherein a bridge arm of each phase in the three-phase asymmetric half-bridge circuit consists of a controllable power switch tube and a diode, and the control method of the switched reluctance motor is characterized by comprising the following steps:

step S1, when the position angle θ of the motor rotor is in the first phase conducting interval, counting the falling edge of the first phase PWM modulation waveform from 0 from the second phase end time, and counting the falling edge as CountA, wherein the first phase and the second phase are two phases of a phase, a phase B and a phase C of the three-phase asymmetric half-bridge circuit, respectively, and the second phase is earlier than the first phase in one period;

step S2, when the first phase PWM modulation waveform detects a rising edge, the upper power switch tube and the lower power switch tube of the first phase output high level;

step S3, when the first phase PWM modulation waveform detects a falling edge, if CountA is an odd number, the upper power switch tube of the first phase outputs a high level, and the upper power switch tube of the second phase outputs a low level; if the CountA is an even number, the upper power switch tube of the first phase outputs a low level, and the upper power switch tube of the second phase outputs a high level;

and step S4, when the position angle theta of the motor rotor is outside the first phase conduction interval, the upper power switch tube and the lower power switch tube of the first phase output low level.

2. The method as claimed in claim 1, wherein the switched reluctance motor comprises a three-phase asymmetric half-bridge circuit, the phase a comprises an upper power switch VT11 and a lower power switch VT12, the turn-on or turn-off of the upper power switch VT11 is controlled by G11, and the turn-on or turn-off of the lower power switch VT12 is controlled by G12.

3. The method as claimed in claim 1, wherein the switched reluctance motor comprises a three-phase asymmetric half-bridge circuit, the B-phase comprises an upper power switch VT21 and a lower power switch VT22, the turn-on or turn-off of the upper power switch VT21 is controlled by G21, and the turn-on or turn-off of the lower power switch VT22 is controlled by G22.

4. The method as claimed in claim 1, wherein the switched reluctance motor comprises a three-phase asymmetric half-bridge circuit, the C phase comprises an upper power switch VT31 and a lower power switch VT32, the turn-on or turn-off of the upper power switch VT31 is controlled by G31, and the turn-on or turn-off of the lower power switch VT32 is controlled by G32.

Technical Field

The application belongs to the technical field of aviation motor control, and particularly relates to a control method of a switched reluctance motor.

Background

At present, aviation high-voltage direct current becomes one of the development directions of airplane power systems, and a switched reluctance motor becomes a research hotspot of a high-voltage direct current starting/generating system due to the advantages of simple structure, suitability for high rotating speed and the like.

For the switched reluctance starting/generating power conversion topology, many studies are made at home and abroad, and a common topology structure is a three-phase asymmetric half-bridge power topology as shown in fig. 1.

In the topology of fig. 1, the three-phase asymmetric half-bridge circuit is mainly composed of a three-phase asymmetric half-bridge circuit, a starting input power supply, a generated voltage output capacitor C2 and an exciting diode D3. Wherein the bridge arm of each phase in the asymmetric half-bridge circuit consists of a controllable power switch tube and a diode; the anode of the excitation diode is connected with the positive end of the power generation voltage output, and the cathode of the excitation diode is connected with the positive end of the excitation input voltage.

Most of the traditional switched reluctance motors are A, B, C three phases, and due to the working principle of the switched reluctance motors, A, B, C three-phase windings are respectively conducted by 180 electrical degrees. Because of the symmetry of A, B, C three phases, the phase difference between the phases is 120 electrical degrees, so there are overlapping conduction intervals of 60 electrical degrees between phase a and phase B, between phase B and phase C, and between phase C and phase a, as shown in fig. 2, where S1 is a schematic diagram of the conduction interval corresponding to the motor rotor position angle θ and the phase a winding, S2 is a schematic diagram of the conduction interval corresponding to the motor rotor position angle θ and the phase B winding, and S3 is a schematic diagram of the conduction interval corresponding to the motor rotor position angle θ and the phase C winding.

When the position of the motor rotor is in a section where a certain phase winding needs to be conducted, the phase current of the winding needs to be judged, a modulation wave is generated, and then a power switching tube in an asymmetric half-bridge arm is controlled. When the current of the winding is overlarge, the power switch tube in the upper bridge arm or the lower bridge arm is turned off; when the winding current is small, the power switching tubes in the upper bridge arm and the lower bridge arm are conducted; and when the position of the motor rotor is in an interval where the phase winding needs to be switched off, the power switching tubes on the two bridge arms are switched off. Therefore, each phase winding can be divided into four working modes by the on-off state of the power switch tube in a certain phase asymmetric half bridge: the device comprises a positive-pressure excitation mode, a zero-pressure upper tube follow current mode, a zero-pressure lower tube follow current mode and a negative-pressure demagnetization mode.

In a traditional control strategy, taking phase A as an example, when the position angle theta of the motor rotor is in the phase A conduction interval, namely theta is satisfied_Aon≤θ≤θ_AoffWhen the current in the A-phase winding is overlarge, a power switching tube in an upper bridge arm or a lower bridge arm is turned off to enable the circuit to work in a zero-voltage tube follow current or zero-voltage tube follow current mode, and the alternating working mode of one-time zero-voltage tube follow current and one-time zero-voltage tube follow current is met; if the current in the A-phase winding is too small, switching on power switching tubes in an upper bridge arm and a lower bridge arm to enable the circuit to work in a positive-voltage excitation mode; B. the same applies to phase C.

Therefore, when the position angle θ of the motor rotor is in the interval where A, B two phases, B, C two phases or C, A two phases are simultaneously conducted, because there is no cross-linking relationship between the phases, each phase is independently controlled, taking A, B overlapping conduction intervals as an example, the timing chart of the control signal is shown in fig. 3. In the figure, S1 is a relative position waveform between a position angle θ of a motor rotor and an a-phase winding conduction interval, S2 is a relative position waveform between a position angle θ of the motor rotor and a B-phase winding conduction interval, IA is an a-phase winding current waveform, IB is a B-phase winding current waveform, ID is a diode D3 current, S4 is an a-phase PWM modulation waveform generated according to an a-phase current, S5 is a B-phase PWM modulation waveform generated according to a B-phase current, G11 is a control signal of a switching tube VT11, G12 is a control signal of the switching tube VT12, G21 is a control signal of the switching tube VT21, and G22 is a control signal of the switching tube VT 22.

In fig. 3, in the first phase, the a phase works in a positive-voltage excitation mode, the switching tubes VT11 and VT12 are switched on, the B phase works in a positive-voltage excitation mode, and the switching tubes VT21 and VT22 are switched on; in the second phase, the A phase works in a zero-voltage tube freewheeling mode, the switching tube VT11 is switched on, the VT12 is switched off, the current freewheels through D12, D3 and VT11, the peak value is I, the B phase works in a positive-voltage excitation mode, and the switching tube VT21 and the VT22 are switched on; in the third stage, the phase A works in a zero-voltage tube freewheeling mode, the switching tube VT11 is switched on, the switching tube VT12 is switched off, the current freewheels through D12, D3 and VT11, the peak current is I, the phase B works in the zero-voltage tube freewheeling mode, the switching tube VT21 is switched on and the VT22 is switched off, the current freewheels through D22, D3 and VT21, the peak current is I, and the current peak value of the diode D3 is 2I; in the fourth stage, the phase A works in a positive-pressure excitation mode, the switching tubes VT11 and VT12 are conducted, the phase B works in the positive-pressure excitation mode, and the switching tubes VT21 and VT22 are conducted; in the phase, the phase A works in a zero-voltage low-tube follow current mode, the switching tube VT12 is switched on, the switching tube VT11 is switched off, the current flows through the D11 and the VT12, the follow current is I, the phase B works in a positive-voltage excitation mode, and the switching tube VT21 and the VT22 are switched on; in the stage, the phase A works in a zero-voltage tube follow current mode, the switching tube VT12 is switched on, the VT11 is switched off, the current flows after current through the D11 and the VT12, the follow current is I, the phase B works in the zero-voltage tube follow current mode, the switching tube VT22 is switched on, the VT21 is switched off, the current flows after current through the D21 and the VT22, and the follow current is I.

From the above analysis, due to the zero-voltage tube freewheeling mode, there is current in the diode D3, and when both the two phases are the zero-voltage tube freewheeling mode, the peak value of the current is 2I, i.e. the working stage c in the above diagram, and the circuit diagram is shown in fig. 4.

When the current value of the power device is determined, the effective value and the peak value need to be simultaneously considered, and the current passing through the diode D3 is not continuous current, so the difference between the effective value and the peak value is large. If the device which accords with the effective value is adopted, the diode always works under the overload working condition in the working process, the service life of the diode is reduced, and the reliability of the switched reluctance starting/generating system is influenced; if the device corresponding to the current peak is adopted, the volume weight of the device is increased. Therefore, how to reduce the overload current of the power diode, prolong the service life of the diode and improve the reliability of the switched reluctance starting/generating system through the adjustment of the control strategy becomes a technical difficulty.

Disclosure of Invention

In order to solve the technical problem, the invention provides a control strategy of the switched reluctance motor aiming at the power grade of the power device at the present stage, so that the overload current of the power diode is reduced, the service life of the power diode is prolonged, and the working reliability of the switched reluctance starting/generating system is improved.

The application provides a switched reluctance motor control method, the switched reluctance motor comprises a three-phase asymmetric half-bridge circuit A phase, a B phase, a C phase, a starting input capacitor C1, a generating voltage output capacitor C2 and an exciting diode D3, wherein a bridge arm of each phase in the three-phase asymmetric half-bridge circuit is composed of a controllable power switch tube and a diode, and the switched reluctance motor control method comprises the following steps:

step S1, when the position angle θ of the motor rotor is in the first phase conducting interval, counting the falling edge of the first phase PWM modulation waveform from 0 from the second phase end time, and counting the falling edge as CountA, where the first phase and the second phase are two phases of a phase, a phase B and a phase C of the three-phase asymmetric half-bridge circuit, respectively, and the second phase is earlier than the first phase in one cycle.

In this step, for example, if the first phase is the a phase, the second phase is the C phase, if the first phase is the B phase, the second phase is the a phase, and if the first phase is the C phase, the second phase is the B phase.

Step S2, when the first phase PWM modulation waveform detects a rising edge, the upper power switch tube and the lower power switch tube of the first phase output a high level.

Step S3, when the first phase PWM modulation waveform detects a falling edge, if CountA is an odd number, the upper power switch tube of the first phase outputs a high level, and the upper power switch tube of the second phase outputs a low level; if CountA is an even number, the upper power switch tube of the first phase outputs a low level, and the upper power switch tube of the second phase outputs a high level.

And step S4, when the position angle theta of the motor rotor is outside the first phase conduction interval, the upper power switch tube and the lower power switch tube of the first phase output low level.

Preferably, the switched reluctance motor comprises an A phase of a three-phase asymmetric half-bridge circuit, wherein the A phase comprises an upper power switch tube VT11 and a lower power switch tube VT12, the on or off of the upper power switch tube VT11 is controlled by G11, and the on or off of the lower power switch tube VT12 is controlled by G12.

Preferably, the switched reluctance motor comprises a three-phase asymmetric half-bridge circuit, wherein the phase B comprises an upper power switch tube VT21 and a lower power switch tube VT22, the on or off of the upper power switch tube VT21 is controlled by G21, and the on or off of the lower power switch tube VT22 is controlled by G22.

Preferably, the switched reluctance motor comprises a three-phase asymmetric half-bridge circuit, wherein the C phase comprises an upper power switch tube VT31 and a lower power switch tube VT32, the turn-on or turn-off of the upper power switch tube VT31 is controlled by G31, and the turn-on or turn-off of the lower power switch tube VT32 is controlled by G32.

The application reduces the overload current of the power diode, prolongs the service life of the power diode, and increases the working reliability of the switched reluctance starting/generating system.

Drawings

Fig. 1 is a schematic diagram of a switched reluctance three-phase asymmetric half-bridge power topology.

Fig. 2 is a three-phase winding turn-on timing diagram.

Fig. 3 is a timing diagram of A, B overlapping conduction intervals under a conventional control strategy.

Fig. 4 is a circuit diagram of A, B two-phase zero-voltage tube-freewheeling mode.

Fig. 5A is a schematic diagram of a phase a zero voltage upper pipe follow current and a phase B zero voltage lower pipe follow current in a preferred embodiment of the switched reluctance motor control method of the present application.

Fig. 5B is a schematic diagram of a phase a zero voltage decrease pipe follow current and a phase B zero voltage increase pipe follow current according to a preferred embodiment of the switched reluctance motor control method of the present application.

Fig. 6 is a timing diagram of A, B overlapping conduction interval control signals under the novel control strategy.

Detailed Description

In order to make the implementation objects, technical solutions and advantages of the present application clearer, the technical solutions in the embodiments of the present application will be described in more detail below with reference to the accompanying drawings in the embodiments of the present application. In the drawings, the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The described embodiments are some, but not all embodiments of the present application. The embodiments described below with reference to the drawings are exemplary and intended to be used for explaining the present application, and should not be construed as limiting the present application. All other embodiments obtained by a person of ordinary skill in the art without any inventive work based on the embodiments in the present application are within the scope of protection of the present application. Embodiments of the present application will be described in detail below with reference to the drawings.

The application provides a control method of a switched reluctance motor, wherein the switched reluctance motor comprises a three-phase asymmetric half-bridge circuit A phase, a B phase, a C phase, a starting input capacitor C1, a generating voltage output capacitor C2 and an exciting diode D3, wherein a bridge arm of each phase in the three-phase asymmetric half-bridge circuit is composed of a controllable power switch tube and a diode.

According to the invention, when the position angle of the motor rotor is in the two-phase winding overlapping conduction interval, the logical relation between the control signals of the two corresponding switching tubes is increased, namely, the phase A is alternated with the phase B, the phase B is alternated with the phase C, and the phase C is alternated with the phase A. Therefore, zero-voltage tube freewheeling is avoided when two phases are conducted simultaneously, freewheeling of only one phase through the diode D3 in the overlapped conduction interval is achieved, and the current peak value of the diode D3 is reduced.

The control method of the switched reluctance motor comprises the following steps:

step S1, when the position angle θ of the motor rotor is in the first phase conducting interval, counting the falling edge of the first phase PWM modulation waveform from 0 from the second phase end time, and counting the falling edge as CountA, wherein the first phase and the second phase are two phases of a phase, a phase B and a phase C of the three-phase asymmetric half-bridge circuit, respectively, and the second phase is earlier than the first phase in one period;

step S2, when the first phase PWM modulation waveform detects a rising edge, the upper power switch tube and the lower power switch tube of the first phase output high level;

step S3, when the first phase PWM modulation waveform detects a falling edge, if CountA is an odd number, the upper power switch tube of the first phase outputs a high level, and the upper power switch tube of the second phase outputs a low level; if the CountA is an even number, the upper power switch tube of the first phase outputs a low level, and the upper power switch tube of the second phase outputs a high level;

and step S4, when the position angle theta of the motor rotor is outside the first phase conduction interval, the upper power switch tube and the lower power switch tube of the first phase output low level.

In the control strategy of the invention, taking A, B phases as an example of overlapping conduction, when A, B phases are all in a zero-voltage freewheeling mode, if a phase A adopts a zero-voltage upper-tube freewheeling mode, a phase B adopts a zero-voltage lower-tube freewheeling mode; if the phase A adopts a zero-pressure tube follow current mode, the phase B adopts a zero-pressure tube follow current mode, and the A, B two-phase zero-pressure follow current mode is a mode that zero-pressure tube follow current and zero-pressure tube follow current are alternately carried out. The circuit diagram is shown in fig. 5.

Through logic analysis, the control strategy of the invention meets the following logic relationship:

when the rotor position angle of the motor is at theta_Bon≤θ≤θ_AoffWhen S4 is 0 or S5 is 0,

when the rotor position angle of the motor is at theta_Con≤θ≤θ_BoffWhen S5 is 0 or S6 is 0,

when the rotor position angle of the motor is at theta_Aon≤θ≤θ_CoffWhen S6 is 0 or S4 is 0,

meanwhile, G11 and G12 satisfy the in-phase alternating chopping logic; g21 and G22 satisfy the in-phase alternating chopping logic; g31 and G32 satisfy the in-phase alternating chopping logic. The alternate chopping logic is as follows:

when the position angle theta of the motor rotor is in the A-phase conduction interval, theta is satisfied_Coff≤θ≤θ_AoffWhen theta is equal to theta_CoffAt the beginning of the time, the falling edge of the a-phase PWM modulation waveform S2 is counted from 0 and counted as CountA.

When the A-phase PWM modulation waveform S2 detects a rising edge, G11 and G12 output high level;

thirdly, when the falling edge is detected by the A-phase PWM waveform S2, if CountA is odd,

G11＝1

if the number CountA is an even number,

G11＝0

when the position angle theta of the motor rotor does not satisfy theta_Aon≤θ≤θ_AoffAt this time, G11 and G12 output low levels.

The logic of alternate chopping in phase B and C is similar to that of phase A, and phase B satisfies the interval theta_Aoff≤θ≤θ_BoffC phase satisfies the interval theta_Boff≤θ≤θ_CoffAnd the rest will not be described in detail.

In the following diagram, for example, A, B phases are overlapped to be conducted to the B-phase single conduction interval, and the timing diagram of the control signal of the switch tube is shown in fig. 6. In the figure, S1 is a relative position waveform between a position angle θ of a motor rotor and an a-phase winding conduction interval, S2 is a relative position waveform between a position angle θ of the motor rotor and a B-phase winding conduction interval, IA is an a-phase winding current waveform, IB is a B-phase winding current waveform, ID is a diode D3 current, S4 is an a-phase PWM modulation waveform generated according to an a-phase current, S5 is a B-phase PWM modulation waveform generated according to a B-phase current, G11 is a control signal of a switching tube VT11, G12 is a control signal of the switching tube VT12, G21 is a control signal of the switching tube VT21, and G22 is a control signal of the switching tube VT 22.

As shown in fig. 6, in the first phase, the a phase works in a positive-voltage excitation mode, the switching tubes VT11 and VT12 are switched on, the B phase works in a positive-voltage excitation mode, and the switching tubes VT21 and VT22 are switched on; in the second phase, the A phase works in a zero-voltage tube freewheeling mode, the switching tube VT11 is switched on, the VT12 is switched off, the current freewheels through D12, D3 and VT11, the peak value is I, the B phase works in a positive-voltage excitation mode, and the switching tube VT21 and the VT22 are switched on; in the third stage, the phase A works in a zero-voltage tube-feeding follow current mode, the switching tube VT11 is switched on, the switching tube VT12 is switched off, current flows through D12, D3 and VT11, peak current is I, the phase B works in a zero-voltage tube-feeding follow current mode, the switching tube VT22 is switched on and VT21 is switched off, the current flows through D21 and VT22, the peak current is I, and the current peak value of the diode D3 is I; in the fourth stage, the phase A works in a positive-pressure excitation mode, the switching tubes VT11 and VT12 are conducted, the phase B works in the positive-pressure excitation mode, and the switching tubes VT21 and VT22 are conducted; in the phase, the phase A works in a zero-voltage low-tube follow current mode, the switching tube VT12 is switched on, the switching tube VT11 is switched off, the current flows through the D11 and the VT12, the follow current is I, the phase B works in a positive-voltage excitation mode, and the switching tube VT21 and the VT22 are switched on; in the stage, the phase A works in a zero-voltage tube follow current mode, the switching tube VT12 is switched on, the switching tube VT11 is switched off, the current flows after current through the D11 and the VT12, the follow current is I, the phase B works in a zero-voltage tube follow current mode, the switching tube VT21 is switched on, the VT22 is switched off, the current flows after current through the D22 and the VT21, and the follow current is I.

In the above diagram, it can be seen that through the adjustment of the control strategy, the peak value of the current passing through the diode D3 is reduced to I, so that the magnitude of the overload current is effectively reduced, the service life of the power diode is prolonged, and the reliability of the operation of the switched reluctance starting/generating system is increased.

The invention provides a control strategy of a switched reluctance motor aiming at the traditional single-three-phase asymmetric half-bridge power topology, reduces the overload current of a power diode, prolongs the service life of the power diode and increases the working reliability of a switched reluctance starting/generating system.

The above description is only for the specific embodiments of the present application, but the scope of the present application is not limited thereto, and any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope of the present application should be covered within the scope of the present application. Therefore, the protection scope of the present application shall be subject to the protection scope of the claims.