阅读说明：本技术 一种单极性电机驱动器及其转矩损耗比控制方法 (Unipolar motor driver and torque loss ratio control method thereof ) 是由 蒋栋 李安 刘自程 孙翔文 于 2020-12-22 设计创作，主要内容包括：本发明公开了一种单极性电机驱动器及其转矩损耗比控制方法,属于交流电机驱动控制领域,单极性电机驱动器包括：单极性流出桥臂、N-1个复用桥臂、单极性流入桥臂和N相定子绕组,N为电机的总相数,N≥3；单极性流出桥臂、复用桥臂和单极性流入桥臂均由依次连接在直流母线电压节点与电源地之间的上桥臂开关和下桥臂开关组成,上桥臂开关和下桥臂开关的连接点为桥臂输出节点；N相定子绕组依次等间隔设置并首尾相连引出N+1个绕组节点,N+1个绕组节点与N+1个桥臂输出节点一一对应连接。在不增加功率器件数量和容量的同时,具备零轴直流电流注入能力和容错能力,并提高直流电压利用率和调速范围,有效降低电机驱动系统的成本、体积和功率损耗。(The invention discloses a unipolar motor driver and a torque loss ratio control method thereof, belonging to the field of alternating current motor drive control, wherein the unipolar motor driver comprises the following components: the motor comprises a unipolar outflow bridge arm, N-1 multiplexing bridge arms, a unipolar inflow bridge arm and an N-phase stator winding, wherein N is the total phase number of the motor and is more than or equal to 3; the single-polarity outflow bridge arm, the multiplexing bridge arm and the single-polarity inflow bridge arm are all composed of an upper bridge arm switch and a lower bridge arm switch which are sequentially connected between a direct-current bus voltage node and a power ground, and the connection point of the upper bridge arm switch and the lower bridge arm switch is a bridge arm output node; the N-phase stator windings are sequentially arranged at equal intervals and connected end to lead out N +1 winding nodes, and the N +1 winding nodes are connected with the N +1 bridge arm output nodes in a one-to-one correspondence mode. The motor driving system has zero-axis direct current injection capability and fault-tolerant capability without increasing the number and capacity of power devices, improves the direct voltage utilization rate and the speed regulation range, and effectively reduces the cost, the volume and the power loss of the motor driving system.)

1. A unipolar motor driver, comprising: the motor comprises a unipolar outflow bridge arm, N-1 multiplexing bridge arms, a unipolar inflow bridge arm and an N-phase stator winding, wherein N is the total phase number of the motor and is more than or equal to 3;

the single-polarity outflow bridge arm, the multiplexing bridge arm and the single-polarity inflow bridge arm are all composed of an upper bridge arm switch and a lower bridge arm switch which are sequentially connected between a direct-current bus voltage node and a power ground, the connection point of the upper bridge arm switch and the lower bridge arm switch is a bridge arm output node, and the number of the bridge arm output nodes is N + 1;

the N-phase stator windings are sequentially arranged at equal intervals and connected end to lead out N +1 winding nodes, and the N +1 winding nodes are connected with the N +1 bridge arm output nodes in a one-to-one correspondence mode.

2. The unipolar motor driver according to claim 1, wherein in the unipolar outgoing leg, an anode of an upper leg switch is connected to the dc bus voltage node, a cathode of a lower leg switch is connected to the power ground, and a cathode of the upper leg switch is connected to an anode of the lower leg switch;

the upper bridge arm switch is a power device with current being conducted from the positive pole to the negative pole in a one-way controllable mode, and the lower bridge arm switch is a power device with current being conducted from the negative pole to the positive pole in a one-way uncontrollable mode.

3. The unipolar motor driver according to claim 1, wherein in the multiplexed legs, an anode of an upper leg switch is connected to the dc bus voltage node, a cathode of a lower leg switch is connected to the power ground, and a cathode of the upper leg switch is connected to an anode of the lower leg switch; the upper bridge arm switch and the lower bridge arm switch are power devices with bidirectional controllable breakover current.

4. The unipolar motor driver according to claim 3, wherein in the multiplexing bridge arms, the upper bridge arm switches are IGBTs provided with anti-parallel diodes or MOSFETs provided with anti-parallel diodes; the lower bridge arm switch is an IGBT provided with an anti-parallel diode or an MOSFET provided with an anti-parallel diode.

5. The unipolar motor driver according to claim 1, wherein the unipolar current flows into the bridge arms, an anode of the upper bridge arm switch is connected to the dc bus voltage node, a cathode of the lower bridge arm switch is connected to the power ground, and a cathode of the upper bridge arm switch is connected to an anode of the lower bridge arm switch; the upper bridge arm switch is a power device with current from the negative electrode to the positive electrode in one-way uncontrollable conduction, and the lower bridge arm switch is a power device with current from the positive electrode to the negative electrode in one-way controllable conduction.

6. A unipolar motor driver according to any one of claims 1-5, wherein the electrical angle difference between adjacent two phases of stator windings is Δ N, and Δ N is coprime to N.

7. The unipolar motor driver according to claim 6, wherein when N is an odd number, 1. ltoreq. Δ n.ltoreq (N-1)/2; when N is an even number, delta N is more than or equal to 1 and less than or equal to 0.5N-1.

8. A method of controlling a torque loss ratio of a unipolar motor driver, comprising:

s1, calculating total loss generated in each bridge arm of the unipolar motor driver, wherein the total loss is related to current output by the unipolar motor driver, and the current comprises a direct current component and an alternating current component;

s2, constructing a Lagrangian function based on the total loss and the torque generated by the unipolar motor driver in the motor, and enabling the first-order partial derivatives of the Lagrangian function to be 0 with respect to the direct current component, the alternating current component and the Lagrangian multiplier pair to obtain the ratio of the direct current component to the alternating current component when the torque loss ratio is maximum;

and S3, calculating PWM driving signals of the bridge arm switches according to the ratio of the direct current component to the alternating current component obtained in the step S2 so as to drive the motor.

9. A unipolar motor driver torque loss ratio control method according to claim 8, wherein said unipolar motor driver is according to any one of claims 1 to 7, the losses in said unipolar outgoing leg and unipolar incoming leg being related to said direct current component and alternating current component, the losses in said multiplexed leg being related to said alternating current component.

10. The unipolar motor driver torque loss ratio control method according to claim 9, wherein when N-3, the lagrangian function constructed in S2 is:

wherein, F (I)_AC,I_DCλ) is the Lagrangian function, V_onIs the on-state voltage, V, of the bridge arm switch_dcIs the output voltage of the unipolar motor driver, t_swFor rise and fall times of bridge arm switches, N_sIs the number of switching times in one fundamental period, I_ACIs an alternating current component, I_DCIs a DC component, λ is a Lagrange multiplier pair, T_e ^*Is a torque reference value, P is the pole pair number of the motor, L_dIs the primary alternating component of the stator inductance in the motor.

Technical Field

The invention belongs to the field of alternating current motor drive control, and particularly relates to a unipolar motor driver and a torque loss ratio control method thereof.

Background

In recent years, in the fields of high reliability, high speed and the like, the doubly salient reluctance motor has attracted wide attention in the industry due to the advantages of simple structure, flexible control, no risk caused by permanent magnets and the like. The stator side of the motor only comprises one set of concentrated winding, the rotor side only comprises silicon steel sheets, and the special stator-rotor structure causes that the driver of the novel motor is greatly different from the traditional alternating current motor driver.

In terms of topological structure, a traditional motor controller based on a half-bridge type topology only has pure alternating current control capability, the novel motor requires a driver to have control capability of alternating current and direct current at the same time, and a large amount of harmonic components contained in back electromotive force of the motor need to be suppressed, so that the topology of the novel motor driver has more control freedom degrees. Therefore, the prior art adopts a full-bridge topology with dc current control capability as the topology of this new type of motor driver. But the cost, volume and power consumption of a full-bridge topology is twice that of a half-bridge topology. This greatly hinders the large-scale deployment of new motor drive systems in industry.

In the aspect of current control, in order to optimize the efficiency of a novel motor system, a maximum torque-to-current ratio control technology, referred to as MTPA control, exists in the prior art. MTPA control requires that the effective values of the dc component and the ac component be the same so that the total effective value of the required phase currents is minimal when the same torque is output. The method is not optimized by taking a motor driving system as a whole, and when the topological structure of the motor driver is changed, the loss generated by different current components is changed, so that the MTPA method cannot achieve the efficiency optimization of a novel motor system, and simultaneously, the driver has bidirectional current circulation capacity, and the optimization space of the driver is limited.

Disclosure of Invention

Aiming at the defects and improvement requirements of the prior art, the invention provides a unipolar motor driver and a torque loss ratio control method thereof, and aims to solve the problems of large number of switching tubes, low power density and large power loss of the existing novel motor driver while ensuring the working range of a motor.

To achieve the above object, according to one aspect of the present invention, there is provided a unipolar motor driver including: the motor comprises a unipolar outflow bridge arm, N-1 multiplexing bridge arms, a unipolar inflow bridge arm and an N-phase stator winding, wherein N is the total phase number of the motor and is more than or equal to 3; the single-polarity outflow bridge arm, the multiplexing bridge arm and the single-polarity inflow bridge arm are all composed of an upper bridge arm switch and a lower bridge arm switch which are sequentially connected between a direct-current bus voltage node and a power ground, the connection point of the upper bridge arm switch and the lower bridge arm switch is a bridge arm output node, and the number of the bridge arm output nodes is N + 1; the N-phase stator windings are sequentially arranged at equal intervals and connected end to lead out N +1 winding nodes, and the N +1 winding nodes are connected with the N +1 bridge arm output nodes in a one-to-one correspondence mode.

Furthermore, in the unipolar outflow bridge arm, the anode of the upper bridge arm switch is connected with the direct-current bus voltage node, the cathode of the lower bridge arm switch is connected with the power ground, and the cathode of the upper bridge arm switch is connected with the anode of the lower bridge arm switch; the upper bridge arm switch is a power device with current being conducted from the positive pole to the negative pole in a one-way controllable mode, and the lower bridge arm switch is a power device with current being conducted from the negative pole to the positive pole in a one-way uncontrollable mode.

Furthermore, in the multiplexing bridge arm, the anode of the upper bridge arm switch is connected with the direct-current bus voltage node, the cathode of the lower bridge arm switch is connected with the power ground, and the cathode of the upper bridge arm switch is connected with the anode of the lower bridge arm switch; the upper bridge arm switch and the lower bridge arm switch are power devices with bidirectional controllable breakover current.

Furthermore, in the multiplexing bridge arm, the upper bridge arm switch is an IGBT provided with an anti-parallel diode or an MOSFET provided with an anti-parallel diode; the lower bridge arm switch is an IGBT provided with an anti-parallel diode or an MOSFET provided with an anti-parallel diode.

Furthermore, the unipolar current flows into the bridge arm, the positive electrode of the upper bridge arm switch is connected with the direct-current bus voltage node, the negative electrode of the lower bridge arm switch is connected with the power ground, and the negative electrode of the upper bridge arm switch is connected with the positive electrode of the lower bridge arm switch; the upper bridge arm switch is a power device with current from the negative electrode to the positive electrode in one-way uncontrollable conduction, and the lower bridge arm switch is a power device with current from the positive electrode to the negative electrode in one-way controllable conduction.

Furthermore, the electrical angle difference between the adjacent two phases of stator windings is Δ N, and Δ N and N are relatively prime.

Furthermore, when N is an odd number, 1 is more than or equal to Δ N is more than or equal to (N-1)/2; when N is an even number, delta N is more than or equal to 1 and less than or equal to 0.5N-1.

According to another aspect of the present invention, there is provided a unipolar motor driver torque loss ratio control method including: s1, calculating total loss generated in each bridge arm of the unipolar motor driver, wherein the total loss is related to current output by the unipolar motor driver, and the current comprises a direct current component and an alternating current component; s2, constructing a Lagrangian function based on the total loss and the torque generated by the unipolar motor driver in the motor, and enabling the first-order partial derivatives of the Lagrangian function to be 0 with respect to the direct current component, the alternating current component and the Lagrangian multiplier pair to obtain the ratio of the direct current component to the alternating current component when the torque loss ratio is maximum; and S3, calculating PWM driving signals of the bridge arm switches according to the ratio of the direct current component to the alternating current component obtained in the step S2 so as to drive the motor.

Further, the unipolar motor driver is the unipolar motor driver as described above, the losses in the unipolar outgoing leg and the unipolar incoming leg are related to the direct current component and the alternating current component, and the loss in the multiplexing leg is related to the alternating current component.

Further, when N is 3, the lagrangian function constructed in S2 is:

wherein, F (I)_AC,I_DCλ) is the Lagrangian function, V_onIs the on-state voltage of the bridge arm switch,V_dcis the output voltage of the unipolar motor driver, t_swFor rise and fall times of bridge arm switches, N_sIs the number of switching times in one fundamental period, I_ACIs an alternating current component, I_DCIs a DC component, λ is a Lagrange multiplier pair, T_e ^*Is a torque reference value, P is the pole pair number of the motor, L_dIs the primary alternating component of the stator inductance in the motor.

Generally, by the above technical solution conceived by the present invention, the following beneficial effects can be obtained:

(1) compared with a full-bridge topological structure, the number of power devices is reduced by a half, the capacity of the power devices is not increased, the half-bridge topological structure is consistent with a half-bridge topological structure commonly used in the industry for driving a traditional motor, and the cost, the volume and the power loss of the driver are effectively reduced; in addition, the direct-current voltage utilization rate of the unipolar motor driver topology is consistent with that of a full-bridge topology, and is twice that of a half-bridge topology, so that the working range of the motor is effectively expanded;

(2) the maximum torque loss ratio control method takes a motor driving system as a whole, and achieves the optimization of efficiency by taking the torque maximization and the loss minimization as targets; in the topology, the loss caused by the direct current is generally smaller than the loss caused by the alternating current, so that the direct current calculated according to the maximum torque loss ratio is always larger than the amplitude of the alternating current, and the topology can realize the optimal control of the motor.

Drawings

Fig. 1 is a topology of a unipolar motor driver provided by an embodiment of the present invention;

fig. 2 is a topology of a three-phase unipolar motor driver provided by an embodiment of the present invention;

fig. 3 is a topology structure of a five-phase unipolar motor driver according to an embodiment of the present invention

Fig. 4 is a block diagram of a three-phase unipolar motor driving system according to an 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.

In the present application, the terms "first," "second," and the like (if any) in the description and the drawings are used for distinguishing between similar elements and not necessarily for describing a particular sequential or chronological order.

Fig. 1 shows a topology of a unipolar motor driver according to an embodiment of the present invention. Referring to fig. 1, a unipolar motor driver in the present embodiment will be described in detail with reference to fig. 2 to 3.

The unipolar motor driver comprises a unipolar outflow bridge arm, N-1 multiplexing bridge arms, a unipolar inflow bridge arm and an N-phase stator winding, wherein N is the total phase number of the motor and is more than or equal to 3. The unipolar outflow bridge arm, the multiplexing bridge arm and the unipolar inflow bridge arm are all composed of an upper bridge arm switch and a lower bridge arm switch which are sequentially connected between a direct-current bus voltage node and a power ground, the connection point of the upper bridge arm switch and the lower bridge arm switch is a bridge arm output node, the number of the bridge arm output nodes is N +1, and the bridge arm output nodes are respectively a node v in the graph 1_l(1) Node v_l(2) … …, node v_l(N + 1). The N-phase stator windings are sequentially arranged at equal intervals and connected end to lead out N +1 winding nodes, and the N +1 winding nodes are connected with the N +1 bridge arm output nodes in a one-to-one correspondence mode. The N-phase stator windings are respectively the stator windings v shown in FIG. 1_p(1) Stator winding v_p(2) … …, stator winding v_p(N) is provided. Node v_l(1) The bridge arm is a unipolar inflow bridge arm; node v_lThe bridge arm where (N +1) is located is a unipolar outflow bridge arm; and bridge arms where other nodes are located are multiplexing bridge arms. Taking the total phase number N of the motor as 3 as an example, the topology structure of the corresponding unipolar motor driver is shown in fig. 2; taking the total phase number N of the motor as 5 as an example, the topology structure of the corresponding unipolar motor driver is as shown in fig. 3Shown in the figure.

In the unipolar outflow bridge arm, the positive electrode of the upper bridge arm switch is connected with a direct current bus voltage node, the negative electrode of the lower bridge arm switch is connected with a power ground, and the negative electrode of the upper bridge arm switch is connected with the positive electrode of the lower bridge arm switch. The upper bridge arm switch is a power device which is in one-way controllable conduction from the positive pole to the negative pole of current, such as an IGBT; the lower bridge arm switch is a power device, such as a power diode, with current being uncontrollably conducted in one direction from the cathode to the anode.

In the multiplexing bridge arm, the anode of an upper bridge arm switch is connected with a direct current bus voltage node, the cathode of a lower bridge arm switch is connected with a power ground, and the cathode of the upper bridge arm switch is connected with the anode of the lower bridge arm switch. The upper bridge arm switch and the lower bridge arm switch are power devices with bidirectional controllable current conduction. Specifically, the upper arm switch and the lower arm switch are IGBTs provided with anti-parallel diodes or MOSFETs provided with anti-parallel diodes.

And the single polarity flows into the bridge arms, the positive electrode of the upper bridge arm switch is connected with the direct current bus voltage node, the negative electrode of the lower bridge arm switch is connected with the power ground, and the negative electrode of the upper bridge arm switch is connected with the positive electrode of the lower bridge arm switch. The upper bridge arm switch is a power device, such as a power diode, with current being conducted from the negative electrode to the positive electrode in a one-way uncontrollable manner; the lower bridge arm switch is a power device, such as an IGBT, with current being controllably conducted in one direction from the positive electrode to the negative electrode.

The electrical angle difference between the adjacent two phases of stator windings is delta N, and delta N and N are relatively prime. Further, when N is an odd number, the value range of delta N is more than or equal to 1 and less than or equal to (N-1)/2. When Δ N is (N-1)/2, the dc voltage utilization of the unipolar motor driver is 2, which is twice that of the half-bridge topology. When N is an even number, the value range of delta N is more than or equal to 1 and less than or equal to 0.5N-1.

Specifically, the 1 st phase of the motor is taken as a reference phase, a left node of a stator winding corresponds to a positive pole of a winding end voltage, a right node of the stator winding corresponds to a negative pole of the winding end voltage, Δ N is an arrangement interval number, possible values of Δ N are integers which are prime with N in 1 to (N-1)/2, and each value of Δ N corresponds to the connection sequence of a phase winding. For multi-phase motors with different phase numbers N, the value numbers of Δ N are different, that is, the connection sequence of the phase windings of the multi-phase motors has various modes. Since 1 and (N-1)/2 must be coprime to N, there are at least two connection sequences for the phase windings of a multiphase motor. When the delta n takes a certain specific value, the corresponding specific phase winding connection sequence and the connection mode of the phase winding and the bridge arm output node are as follows: starting from the first phase, all the stator windings are arranged in the order of electrical angular intervals α × Δ N (1, 1+ Δ N, 1+2 Δ N, … …) and end to end, so that N +1 nodes can be derived. The N +1 electrical nodes are sequentially connected with the output nodes of the unipolar outflow bridge arm, the N-1 multiplexing bridge arm, and the unipolar inflow bridge arm in order to obtain the unipolar motor driver in the embodiment.

The embodiment of the invention also provides a method for controlling the torque loss ratio of the unipolar motor driver. The torque loss ratio control method of the unipolar motor driver in the present embodiment will be described in detail with reference to fig. 2 and 4. The method includes operation S1-operation S3.

In operation S1, a total loss generated in each of the legs of the unipolar motor driver is calculated, the total loss being associated with a current output by the unipolar motor driver, the current including a dc current component and an ac current component.

The total loss generated in each bridge arm refers to the loss generated by all the switching tubes in each bridge arm. In the following embodiments, the unipolar motor driver is taken as the unipolar motor driver in the embodiments shown in fig. 1 to 3 as an example to describe the specific process of the control method. The equation for the output torque of a unipolar motor driver is:

T_e＝1.5PL_dI_acI_dc

wherein P is the pole pair number of the motor, L_δIs the primary alternating component of the stator inductance in the machine, I_acIs the amplitude of the alternating current component, I_dcIs the magnitude of the dc current component.

Current stress average in unipolar out leg for unipolar motor driver driving N-phase motorAnd a valid valueAverage value of current stress flowing in bridge arm with single polarityAnd a valid valueComprises the following steps:

average current stress in multiplexed leg kAnd a valid valueRespectively as follows:

it can be seen that for the unipolar motor drivers in the embodiments shown in fig. 1-3, the losses in the unipolar outgoing and incoming legs are related to the dc and ac current components, and are set to P_uni(I_AC,I_DC) (ii) a The losses in the multiplexing bridge arm are related to the alternating current component and are set to P_mul(I_AC) Whereby the total loss P of the unipolar motor driver_sumComprises the following steps:

P_sum＝2×P_uni(I_AC,I_DC)+(N1)×P_mul(I_AC)

operation S2 is to construct a lagrangian function based on the total loss and the torque generated in the motor by the unipolar motor driver, and to make the first-order partial derivative of the lagrangian function to the dc current component, the ac current component, and the lagrangian multiplier pair be 0, so as to obtain the ratio of the dc current component to the ac current component when the torque loss ratio is maximized.

Constructing Lagrange function F (I) according to a torque formula and a total loss expression_AC,I_DCλ) is:

F(I_AC,I_DC,λ)＝P_sum+λ(T_e ^*-1.5PL_dI_acI_dc)

wherein λ is a lagrange multiplier pair; t is_e ^*For reference torque, a value is given by closed-loop control of the speed loop. Let F (I)_AC,I_DCλ) pair I_ACAnd I_DCThe first partial derivative of the sum lambda is equal to zero, i.e. the total loss P can be obtained_sumMinimum, I_ACAnd I_DCThe ratio of (a) to (b).

Further, in this embodiment, a specific design process is described by taking a unipolar motor driver that drives a three-phase motor as an example. The three-phase motor current is a sinusoidal current with direct current bias, and the expression of each phase current is as follows:

since the three-phase unipolar motor driver can only flow unidirectional current, I_DCRatio I_ACIs large. The specific proportion of the alternating current component to the direct current component is distributed as follows:

multiplexing current stress averages in leg k for a three-phase machineAnd a valid valueRespectively as follows:

taking the power device as an example, which is composed of constant-voltage-drop IGBTs and diodes, the relationship between the loss and the current stress in each bridge arm is as follows:

wherein, P_condIs a conduction loss; p_swLoss for turn-on; i.e. i_legInstantaneous current flowing into a bridge arm;the average current flowing into the bridge arm; t is t_onThe rising time of the voltage when the switching tube is switched on; t is t_offThe voltage drop time when the switching tube is turned off; v_onIs the on-state voltage of the bridge arm switch; t is t_swThe rising and falling time of the bridge arm switch; v_dcIs the output voltage of the unipolar motor driver; n is a radical of_sIs the switching times in one fundamental period.

For the unipolar bridge arms on both sides, the total loss of the bridge arms is as follows:

for a multiplexing bridge arm, the total loss of the bridge arm is as follows:

thus, the total loss of 4 legs in a unipolar motor driver of a three-phase motor is:

based on a torque formula and a total loss expression, the constructed Lagrange function is as follows:

let F (I)_AC,I_DCλ) pair I_ACAnd I_DCThe first partial derivative of the sum lambda is equal to zero, i.e. the total loss P can be obtained_sumMinimum, I_ACAnd I_DCThe ratio of (A) to (B):

in this embodiment, the ratio of the direct current component to the alternating current component calculated according to the maximum torque loss ratio (MTPP) is up to 1.74 times; the ratio calculated from the maximum torque to current ratio (MTPA) used in the prior art is 0.707 times. These two ratios were substituted to find that the loss can be reduced by 10% or more when the MTPP ratio is used. Meanwhile, after the direct current proportion is increased, the bridge arms on the two sides adopt unipolar bridge arms, so that the cost and the volume can be further reduced, and the effect of killing more than one Chinese character is achieved.

In operation S3, a PWM driving signal of each bridge arm switch is calculated according to the ratio of the dc current component to the ac current component obtained in operation S2 to drive the motor.

Referring to FIG. 4, get I_ACAnd I_DCAfter the ratio is obtained, respectively distributing the q-axis current instruction and the 0-axis current instruction; second, each currentComparing the command with the collected three-phase current of the motor, and realizing closed-loop control through a current regulator to obtain voltages of a corresponding d axis, a q axis and a 0 axis; then, the shaft voltage of the bridge arm dq0 is obtained through linear transformation, and then the command value of the phase voltage is obtained through modified PARK inverse transformation, so that the driving signal of each bridge arm switching device of the unipolar motor driver is obtained.

Referring to fig. 2, a unipolar motor driver topology is shown when N is 5, and five-phase stator windings are connected at equal intervals, with an interval of 2. For the structure shown in fig. 2, it can be found that the dc component still only flows through the unipolar bridge arms on both sides, so that the generated loss is less, and when the MPTT control algorithm is adopted for analysis, the proportion of the dc component is increased more, so that the system loss is reduced more. This shows that, in the unipolar motor driver that combines MTPP in the motor of arbitrary looks number, compare traditional full-bridge topology all has great advantage, corresponding power loss, cost volume all can effectively reduce, and is unanimous with half-bridge topology. Meanwhile, the utilization rate of the direct-current voltage is still kept to be 2, which is twice of that of a half-bridge topology, and the control performance is improved.

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.