阅读说明：本技术 一种开绕组永磁同步电机的相电流重构方法及控制系统 (Phase current reconstruction method and control system of open-winding permanent magnet synchronous motor ) 是由 甘醇 张冲 曲荣海 于 2020-05-28 设计创作，主要内容包括：本发明公开了一种开绕组永磁同步电机的相电流重构方法及控制系统,属于电机领域。包括：以逆变器II各桥臂的上开关管驱动信号为触发源,采集各触发时刻母线电流值和逆变器II各桥臂的上开关管驱动信号高电平总数,根据母线电流值和高电平总数获取带零序分量的三相电流值；进行定子电流的磁链分量、转矩分量和零序分量控制；根据比例谐振控制器所需零序电压的正负情况,对逆变器I的桥臂驱动信号和逆变器II的桥臂驱动信号进行移相对齐；根据矢量作用时间实施盲区移相,输出120°调制的SVPWM双逆变器驱动信号并控制电机。本发明只需一个电流传感器,通过移相对齐驱动信号,同时实现开绕组永磁同步电机零序电流抑制及相电流重构,提高系统稳定性。(The invention discloses a phase current reconstruction method and a control system of an open-winding permanent magnet synchronous motor, and belongs to the field of motors. The method comprises the following steps: taking an upper switching tube driving signal of each bridge arm of the inverter II as a trigger source, acquiring a bus current value at each trigger moment and the total number of high levels of the upper switching tube driving signals of each bridge arm of the inverter II, and acquiring a three-phase current value with a zero-sequence component according to the bus current value and the total number of the high levels; controlling flux linkage component, torque component and zero sequence component of stator current; according to the positive and negative conditions of zero sequence voltage required by the proportional resonant controller, carrying out phase shift alignment on a bridge arm driving signal of the inverter I and a bridge arm driving signal of the inverter II; and (4) implementing dead zone phase shift according to the vector action time, outputting 120-degree modulated SVPWM double-inverter driving signals and controlling the motor. According to the invention, only one current sensor is needed, and zero-sequence current suppression and phase current reconstruction of the open-winding permanent magnet synchronous motor are realized simultaneously through phase-shifting alignment of the driving signals, so that the system stability is improved.)

1. A phase current reconstruction method of an open winding permanent magnet synchronous motor is characterized by comprising the following steps:

s1, taking an upper switching tube driving signal of each bridge arm of the inverter II as a trigger source, acquiring a bus current value at each trigger moment and the total high level of the upper switching tube driving signal of each bridge arm of the inverter II, and acquiring a three-phase current value with a zero-sequence component according to the bus current value and the total high level;

s2, collecting the current rotor position of the motor, converting the three-phase current value coordinate into a dq0 coordinate system as feedback, and controlling the flux linkage component, the torque component and the zero sequence component of the stator current;

s3, according to the positive and negative conditions of zero sequence voltage needed by the proportional resonant controller, phase-shifting alignment is carried out on bridge arm driving signals of the inverter I and bridge arm driving signals of the inverter II; wherein the inverter I is an inverter closer to the power source, and the inverter II is an inverter farther from the power source;

and S4, performing blind zone phase shift according to the vector action time, outputting 120-degree modulated SVPWM double-inverter driving signals, and driving and controlling the motor.

2. The phase current reconstruction method of claim 1, wherein phase-shifting the inverter I leg drive signals and the inverter II leg drive signals, comprises:

if the zero sequence voltage required by the proportional resonant controller is positive, redistributing a zero vector, and then driving a bridge arm driving signal S of the inverter II_a2、S_b2、S_c2Driving signals S to bridge arms of the inverter I respectively_c1、S_a1、S_b1Aligning; otherwise, the bridge arm driving signal S of the inverter I is used_a1、S_b1、S_c1Driving signals S to bridge arms of the inverter II respectively_b2、S_c2、S_a2And (4) aligning.

3. The phase current reconstruction method according to claim 1, wherein when the acquired bus current value is an upper bus current, the step S1 specifically includes:

when the rising edge of the driving signal of the upper bridge arm switching tube of each phase winding of the motor corresponding to the inverter II is detected, the current value of a primary bus and the total number of the high levels of the driving signal of the upper switching tube of each bridge arm of the inverter II are respectively collected, sampling is carried out for three times, and the total number n of the high levels of the driving signal of the upper switching tube of each bridge arm of the inverter II is detected₁、n₂、n₃Respectively as corresponding to the bus current values i₁、i₂、i₃A flag bit of (1);

the bus current value i in the switching period₁、i₂、i₃Subtracting the bus current value with the corresponding zone bit difference value as 1, and calculating the three-phase current value i with the zero-sequence component_a、i_b、i_c。

4. The phase current reconstruction method according to claim 3, characterized in that when the phase shift of the bridge arm driving signals of the inverter I and the phase shift of the bridge arm driving signals of the inverter II are aligned, specifically, the rising edges of the bridge arm driving signals are aligned.

5. The phase current reconstruction method according to claim 1, wherein when the acquired bus current value is a lower bus current, the step S1 specifically includes:

when the falling edge of the driving signal of the upper bridge arm switching tube of the inverter II corresponding to each phase winding of the motor is detected, respectively acquiring the current value of a primary bus and the total number of high levels of the driving signal of the upper switching tube of each bridge arm of the inverter II, sampling for three times, obtaining the total number of low levels according to the total number of the high levels of the driving signal of the upper switching tube of each bridge arm of the inverter II, and adding the total number n of the low levels to the total number of the low levels₁、n₂、n₃Respectively as corresponding to the bus current values i₁、i₂、i₃A flag bit of (1);

the bus current value i in the switching period₁、i₂、i₃Subtracting the bus current value with the corresponding zone bit difference value as 1, and calculating the three-phase current value i with the zero-sequence component_a、i_b、i_c。

6. The phase current reconstruction method according to claim 5, characterized in that when the phase shift alignment is performed on the bridge arm driving signals of the inverter I and the bridge arm driving signals of the inverter II, specifically, the falling edges of the bridge arm driving signals are aligned.

7. Phase current reconstruction method according to any of claims 1 to 6, characterized in that said applying a dead-zone phase shift according to a vector action time comprises:

if the effective vector action time does not meet the requirement of the minimum vector retention time, the switching signals corresponding to the double inverters are shifted in phase and staggered in phase while the corresponding edges of the double inverters are shifted in phase, the vector action time is increased, and if the effective vector action time meets the requirement of the minimum vector retention time, the switching signals are not operated.

8. The phase current reconstruction method of any of claims 1-6, further comprising employing a proportional resonant controller based zero vector redistribution strategy to suppress zero sequence current:

if the zero sequence voltage output by the proportional resonant controller is positive, the inverter I increases the action time of a vector 7 in the switching period, and the inverter II increases the action time of a vector 0 in the switching period, otherwise, the inverter I increases the action time of the vector 0 in the switching period, and the inverter II increases the action time of the vector 7 in the switching period.

9. A control system based on the phase current reconstruction method of claim 1, comprising

A controller for performing the phase current reconstruction method;

the open winding inverter is used for providing three-phase voltage with common-mode components for the open winding permanent magnet synchronous motor and inhibiting the zero-sequence components of the motor winding current;

the current sensor is used for measuring a bus current signal;

a position sensor for measuring the rotor position signal.

10. The control system of claim 9, wherein the current sensor is positioned at an upper bus position or a lower bus position of the open-winding inverter.

Technical Field

The invention belongs to the technical field of motors, and particularly relates to a phase current reconstruction method and a control system of an open-winding permanent magnet synchronous motor.

Background

With the problems of world energy shortage and increasingly serious environmental pollution, the traditional electrical industry is developing towards greenization and diversification, the development of the new energy field is more and more emphasized by people, and the industries such as electric automobiles, wind power generation and the like are most concerned.

Because the traditional star connection winding motor system is restricted by the voltage-resistant grade of a battery capacity bottle neck or a single switch device, and meanwhile, the boost module introduces an energy storage inductor, a voltage-stabilizing capacitor and the like, the weight and the volume of the control system are increased, and the development requirements of improving the power grade, the system performance and the like in an electric automobile or a wind power generation system are difficult to meet. Therefore, the double-inverter topology open-winding permanent magnet synchronous motor is produced. Compared with the traditional star-connected winding motor system, the double-inverter topology open-winding permanent magnet synchronous motor scheme has the remarkable advantages of improving the bus voltage utilization rate and the system power level, and has the defect that the zero-sequence current problem is inevitably introduced by the common direct-current bus open-winding topology.

Meanwhile, in a motor driving system adopting vector control, the winding phase current needs to be detected in real time to calculate the stator current flux linkage and the torque component feedback value for closed-loop control. At least two current sensors are needed in a traditional three-phase motor control system, and at least three current sensors are needed in an open winding motor system because the sum of three-phase currents is not zero. The parameter difference among the multiple sensors can generate direct current offset error and gain error during current detection, and the multiple sensors increase the volume and cost of a driving system, so that the industrial development of the system market is hindered.

In this regard, the phase current reconstruction technique is an effective means for reducing the number of sensors and improving the system performance. However, although the zero vector redistribution technology based on the proportional resonant controller (PR controller) can effectively solve the problem of zero sequence current introduced by open winding topology, the problems of complicated vector combination in a switching period, shortened vector action time and the like are brought, so that the phase current reconstruction technology cannot be directly applied to the drive control system.

Disclosure of Invention

Aiming at the defects of the prior art, the invention aims to provide a phase current reconstruction method and a control system of an open winding permanent magnet synchronous motor, and aims to solve the problem that a zero-sequence current suppression strategy and a phase current reconstruction strategy in open winding topology cannot be compatible.

In order to achieve the above object, an aspect of the present invention provides a phase current reconstruction method for an open-winding permanent magnet synchronous motor, including the steps of:

s1, taking an upper switching tube driving signal of each bridge arm of the inverter II as a trigger source, acquiring a bus current value at each trigger moment and the total high level of the upper switching tube driving signal of each bridge arm of the inverter II, and acquiring a three-phase current value with a zero-sequence component according to the bus current value and the total high level;

s2, collecting the current rotor position of the motor, converting the three-phase current value coordinate into a dq0 coordinate system as feedback, and controlling the flux linkage component, the torque component and the zero sequence component of the stator current;

s3, according to the positive and negative conditions of zero sequence voltage needed by the proportional resonant controller, phase-shifting alignment is carried out on bridge arm driving signals of the inverter I and bridge arm driving signals of the inverter II; wherein the inverter I is an inverter closer to the power source, and the inverter II is an inverter farther from the power source;

and S4, performing blind zone phase shift according to the vector action time, outputting 120-degree modulated SVPWM double-inverter driving signals, and driving and controlling the motor.

Further, phase-shifting and aligning the bridge arm driving signal of the inverter I and the bridge arm driving signal of the inverter II comprises:

if the zero sequence voltage required by the proportional resonant controller is positive, redistributing a zero vector, and then driving a bridge arm driving signal S of the inverter II_a2、S_b2、S_c2Driving signals S to bridge arms of the inverter I respectively_c1、S_a1、S_b1Aligning; otherwise, the bridge arm driving signal S of the inverter I is used_a1、S_b1、S_c1Driving signals S to bridge arms of the inverter II respectively_b2、S_c2、S_a2And (4) aligning.

Further, when the acquired bus current value is an upper bus current, the step S1 specifically includes:

when the rising edge of the driving signal of the upper bridge arm switching tube of each phase winding of the motor corresponding to the inverter II is detected, the current value of a primary bus and the total number of the high levels of the driving signal of the upper switching tube of each bridge arm of the inverter II are respectively collected, sampling is carried out for three times, and the total number n of the high levels of the driving signal of the upper switching tube of each bridge arm of the inverter II is detected₁、n₂、n₃Respectively as corresponding to the bus current values i₁、i₂、i₃A flag bit of (1);

the bus current value i in the switching period₁、i₂、i₃Subtracting the bus current value with the corresponding zone bit difference value as 1, and calculating the three-phase current value i with the zero-sequence component_a、i_b、i_c；

And when the phase shift alignment is carried out on the bridge arm driving signal of the inverter I and the bridge arm driving signal of the inverter II, specifically, the rising edges of the bridge arm driving signals are aligned.

Further, when the acquired bus current value is a lower bus current, the step S1 specifically includes:

when the falling edge of the driving signal of the upper bridge arm switching tube of the inverter II corresponding to each phase winding of the motor is detected, respectively acquiring the current value of a primary bus and the total number of high levels of the driving signal of the upper switching tube of each bridge arm of the inverter II, sampling for three times, obtaining the total number of low levels according to the total number of the high levels of the driving signal of the upper switching tube of each bridge arm of the inverter II, and adding the total number n of the low levels to the total number of the low levels₁、n₂、n₃Respectively as corresponding to the bus current values i₁、i₂、i₃A flag bit of (1);

the bus current value i in the switching period₁、i₂、i₃Subtracting the bus current value with the corresponding zone bit difference value as 1, and calculating the three-phase current value i with the zero-sequence component_a、i_b、i_c；

And when the bridge arm driving signals of the inverter I and the bridge arm driving signals of the inverter II are subjected to phase shift alignment, specifically, the falling edges of the bridge arm driving signals are aligned.

Further, the performing the dead zone phase shift according to the vector action time comprises:

if the effective vector action time does not meet the requirement of the minimum vector retention time, the switching signals corresponding to the double inverters are shifted in phase and staggered in phase while the corresponding edges of the double inverters are shifted in phase, the vector action time is increased, and if the effective vector action time meets the requirement of the minimum vector retention time, the switching signals are not operated.

Further, the method also comprises the following step of adopting a zero vector redistribution strategy based on the proportional resonant controller to inhibit the zero sequence current:

if the zero sequence voltage output by the proportional resonant controller is positive, the inverter I increases the action time of a vector 7 in the switching period, and the inverter II increases the action time of a vector 0 in the switching period, otherwise, the inverter I increases the action time of the vector 0 in the switching period, and the inverter II increases the action time of the vector 7 in the switching period.

In another aspect of the present invention, a control system based on the above phase current reconstruction method is provided, which includes

A controller for performing the phase current reconstruction method;

the open winding inverter is used for providing three-phase voltage with common-mode components for the open winding permanent magnet synchronous motor and inhibiting the zero-sequence components of the motor winding current;

the current sensor is used for measuring a bus current signal;

a position sensor for measuring the rotor position signal.

Further, the current sensor is placed at an upper bus position or a lower bus position of the open-winding inverter.

Compared with the prior art, the phase shift alignment method compatible with the zero-sequence current suppression strategy and the phase current reconstruction strategy is provided, so that the problems of vector combination complication, vector action time shortening and the like in a switching period caused by the zero vector redistribution technology are solved, and the use number of sensors is reduced while zero-sequence components in the phase current of the motor winding are suppressed.

Drawings

FIG. 1 is a block diagram of an open-winding permanent magnet synchronous motor drive and system control according to an embodiment of the present invention;

FIG. 2 is a schematic diagram of the bus current state when the vector combination 6-3' is applied according to the embodiment of the present invention;

FIG. 3 is a schematic diagram of the open-winding dual inverter zero vector redistribution according to an embodiment of the present invention;

FIG. 4(a) is a diagram illustrating an exemplary time-shift alignment strategy according to an embodiment of the present invention with Δ t > 0;

FIG. 4(b) is a diagram illustrating an exemplary time-shift alignment strategy according to an embodiment of the present invention, wherein Δ t < 0;

FIG. 5 is a schematic diagram of phase current reconstruction dead zone in accordance with an embodiment of the present invention;

FIG. 6(a) is a schematic diagram of phase shifting of a sector boundary dead zone according to an embodiment of the present invention;

FIG. 6(b) is a schematic diagram of phase shift of the dead zone in the low modulation region according to the embodiment of the present invention.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention. In addition, the technical features involved in the embodiments of the present invention described below may be combined with each other as long as they do not conflict with each other.

The invention provides a phase current reconstruction method of an open-winding permanent magnet synchronous motor, which comprises the following steps:

s1, taking an upper switching tube driving signal of each bridge arm of the inverter II as a trigger source, acquiring a bus current value at each trigger moment and the total high level of the upper switching tube driving signal of each bridge arm of the inverter II, and acquiring a three-phase current value with a zero-sequence component according to the bus current value and the total high level;

s2, collecting the current rotor position of the motor, converting the three-phase current value coordinate into a dq0 coordinate system as feedback, and controlling the flux linkage component, the torque component and the zero sequence component of the stator current;

s3, according to the positive and negative conditions of zero sequence voltage needed by the proportional resonant controller, phase-shifting alignment is carried out on bridge arm driving signals of the inverter I and bridge arm driving signals of the inverter II; wherein the inverter I is an inverter closer to the power source, and the inverter II is an inverter farther from the power source;

and S4, performing blind zone phase shift according to the vector action time, outputting 120-degree modulated SVPWM double-inverter driving signals, and driving and controlling the motor.

Based on the above method, another aspect of the present invention further provides a drive control system of an open-winding permanent magnet synchronous motor as shown in fig. 1, which includes a controller 100, an inverter 1101, an inverter II102, an open-winding permanent magnet synchronous motor 103, a current sensor 104, a position sensor 105, a dc power supply 106, a bus capacitor 107;

the controller 100 is configured to receive and generate an inverter driving signal based on a position signal of the open-winding permanent magnet synchronous motor 103 collected by the position sensor 105 and a bus current signal collected by the current sensor 104;

the open-winding inverter comprises two three-phase full-bridge inverters, namely an inverter I101 and an inverter II102, and 12 switching tubes in total, is connected with a power supply through a bus capacitor by a positive and negative common direct current bus, and is used for providing three-phase voltage with common-mode components for the open-winding permanent magnet synchronous motor 103 and inhibiting the zero-sequence components of the motor winding current;

the current sensor 104 is used for acquiring a bus current signal and solving a three-phase current feedback value of the motor by matching with a switching signal and a phase-shifting alignment method;

and the position sensor 105 is used for acquiring a rotor position signal and feeding the rotor position signal back to the controller for the current coordinate transformation of the motor winding.

Phase center points of three-phase full-bridge inverters on two sides of the open-winding inverter are respectively connected with two input ends of each phase of the open-winding permanent magnet synchronous motor; the direct current buses under the three-phase full-bridge inverters on the two sides are directly connected and are connected with the cathode of the direct current power supply through the cathode of a bus capacitor; and the direct current buses on the three-phase full-bridge inverters on the two sides are connected with the direct current power supply anode through the current sensor and the bus capacitor anode.

Fig. 2 shows the bus current state when the dual inverter action vectors are combined to be 6-3'. It should be noted that, the positive direction of the motor phase current is assumed that the current is output from the inverter I to the open-winding motor, and is output from the open-winding motor to the inverter II; the positive direction of the current sensor points to the inverter I from the inverter II. And only assumes the current positive direction regardless of the actual current transient positive or negative. When the vector combination is obtained, the current state of the bus is i_m＝i_b+i_c. Then, according to the rotation and simplification rules (the specific rotation and simplification rules are described in detail later), the bus current information in the 8 types of dual-inverter vector combination states is respectively derived, and a bus current state table is obtained as follows:

TABLE 1 bus Current State Table

The following description will be made in detail by taking a case where the current sensor is located on the upper bus as an example. Respectively sampling the bus current state i of the right inverter at the rising edge of the switching signal according to the characteristics of the switching signal₁、i₂、i₃And the total number n of high levels of the switching tubes on each bridge arm of the corresponding inverter II₁、n₂、n₃As a flag bit.

Wherein i₁The first phase sample value being the rising edge in the switching cycle, e.g. as shown in FIG. 4(a), when i₁The action vector combination is 4-2' for the sampling result of the rising edge of the A-phase switching signal of the inverter I and the B-phase switching signal of the inverter II, and at the moment, the bus current I₁＝i_bWhich corresponds to a flag bit n₁＝1；

i₂Sampling for the second phase of the rising edge in the switching periodValues, e.g. as shown in FIG. 4(a), when i₂The action vector combination is 6-3' for the sampling result of the B-phase switching signal of the inverter I and the C-phase switching signal of the inverter II, and I is at the moment₂＝i_b+i_cWhich corresponds to a flag bit n₂＝2；

i₃For the last phase sample value of the rising edge in the switching cycle, e.g. as shown in FIG. 4(a), when i₃The action vector combination is 7-7' for the sampling result of the rising edge of the C-phase switching signal of the inverter I and the A-phase switching signal of the inverter II when I is₃＝i_a+i_b+i_cWhich corresponds to a flag bit n₃＝3；

Finally, the current values i₁、i₂、i₃Minus the corresponding flag bit n₁、n₂、n₃Calculating a three-phase current value i with a zero-sequence component from the current value with a difference value of 1_a、i_b、i_c. E.g. the above example, n₂Value ratio n₁A value greater than 1, then i_c＝i₂-i₁；n₃Value ratio n₂A value greater than 1, then i_a＝i₃-i₂Obtaining a three-phase current calculation value:

due to the existence of the zero sequence loop, according to the voltage equation of the open-winding permanent magnet synchronous motor, the topology adopts vector control, and the time phase current has obvious zero sequence components, mainly third harmonic components. As shown in fig. 3, a zero vector redistribution technique based on a PR controller is employed for suppressing the zero sequence current. The action time delta t/2 of the vector 7(111) is increased, the action time delta t/2 of the vector 0(000) is reduced, and the output effective composite vector in the period of the inverter I is kept unchanged; meanwhile, the action time delta t/2 of the vector 7(111) of the inverter II is reduced, the action time delta t/2 of the vector 0(000) is increased, and meanwhile, the output effective composite vector in the period of the inverter II is kept unchanged.

As can be seen from fig. 3, the above steps generate a unipolar common mode voltage with six times of the switching frequency in one switching cycle, and the value is:

wherein u is₀Common mode voltage, U, for dual inverter output to the motor_dcFor the voltage value of the direct current bus, delta T is the zero vector redistribution time length in the switching period, and T is the switching period time length.

Based on a PR controller, the zero vector redistribution principle is combined, the design of a zero sequence current suppression ring is realized, and the zero sequence component of the motor phase current is effectively suppressed.

However, the zero vector redistribution technology causes the drive signals of the double inverters to change, vector combination in a period is seriously complicated, the number of vectors is increased, the action time is shortened, and the realization of a phase current reconstruction technology is not facilitated. For this purpose, the present invention proposes a phase shift alignment strategy, as shown in FIG. 4.

Specifically, when Δ t > 0, as shown in fig. 4(a), the three-phase switching signals of inverter II are shifted so that the rising edge of the a-phase switching signal of inverter II is aligned with the rising edge of the C-phase switching signal of inverter I, the rising edge of the B-phase switching signal of inverter II is aligned with the rising edge of the a-phase switching signal of inverter I, and the rising edge of the C-phase switching signal of inverter II is aligned with the rising edge of the B-phase switching signal of inverter I. When Δ t < 0, as shown in fig. 4(B), the three-phase switching signals of inverter I are shifted so that the rising edge of the a-phase switching signal of inverter I is aligned with the rising edge of the B-phase switching signal of inverter II, the rising edge of the B-phase switching signal of inverter I is aligned with the rising edge of the C-phase switching signal of inverter II, and the rising edge of the C-phase switching signal of inverter I is aligned with the rising edge of the a-phase switching signal of inverter II.

The mode simplifies the action vector combination of the double inverters in the first half period, so that the driving signal meets the requirements of the phase current reconstruction technology.

When the current sampling device operates in an ideal state, signal triggering and current sampling are completed instantly, and the current information can be instantly and effectively sampled without considering the sampling process. However, in an actual motor control system, there are many non-ideal factorsAll result in current sampling that cannot be done instantaneously, e.g. current settling time T of the switching device_setAD sample hold time T_holdDead time T_deadTime delay T of control system_onAnd the like.

Combining the above factors, the minimum duration T of the effective vector action required for reconstructing the phase current can be obtained_minCalculating the formula:

T_min≥T_set+T_hold+T_dead+T_on(3)

as can be seen from the above, the effective vector action time is not less than T_minOtherwise, the bus current sampling information may not be a required stable value, which results in a three-phase current calculation error and a current reconstruction failure.

Fig. 5 shows a voltage vector region in which the effective vector of the inverter II has insufficient time, where the a1 region is a sector boundary portion in the reconstruction dead zone, the a2 region is a low modulation region portion in the reconstruction dead zone, and the B region is a reconstruction normal region.

The phase shift operation at the sector boundary, low modulation region, respectively, is shown in fig. 6. It should be noted that only the inverter II switching signals are focused on, and the inverter I switching signals keep the corresponding rising edges aligned and are synchronously phase-shifted.

FIG. 6(a) shows the switching status in the period of the sector boundary, and it can be seen that the action time of vector 4(100) is too short to meet the minimum retention time requirement, resulting in i₁Sampling fails, at which time the A-phase switching signal is shifted to the left so that the vector 4(100) on-time meets the minimum hold time T_minRequiring;

FIG. 6(b) shows the switch status during the low modulation period, indicating that the action time of vectors 4(100) and 6(110) is too short to meet the minimum retention time requirement, resulting in i₁、i₂Sampling fails, when the A-phase switching signal is shifted to the left and the C-phase switching signal is shifted to the right, so that the action time of the vectors 4(100) and 6(110) meets the minimum holding time T_minAnd (4) requiring.

Finally obtaining the correct sampling current value i₁、i₂、i₃Calculate the correct three phasesCurrent value i_a、i_b、i_cAnd the coordinate is converted into dq0 axis current for stator current flux linkage component proportional integral, torque component proportional integral and zero sequence component proportional resonance three closed-loop control.

And the SVPWM voltage vector distribution mode of 120-degree modulation of the double inverters is adopted, so that the switching period vector combination is simplified, and the realization of the phase current reconstruction technology is facilitated. The effective vector combination of the original double inverters is 64 (8)²) On the basis, the switching signals of the double inverters in the 120-degree SVPWM voltage vector distribution mode are observed, and the switching signals of the inverter II can be regarded as the rotation of the inverter I: s_a2And S_c1Coincidence, S_b2And S_a1Coincidence, S_c2And S_b1Consistent, so the effective action vector combinations are reduced to 8, where S_a1、S_b1、S_c1、S_a2、S_b2、S_c2And driving signals of each phase of the inverter I and the inverter II are respectively.

Those skilled in the art can understand that the invention can also complete phase current reconstruction control when the bus current sensor is arranged on the lower bus, and the trigger source needs to be modified, the bus ammeter needs to be deduced again, the alignment mode needs to be coordinated, the blind zone phase shifting mode needs to be adopted, and the like.

It will be understood by those skilled in the art that the foregoing is only a preferred embodiment of the present invention, and is not intended to limit the invention, and that any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the scope of the present invention.