CN106685148A - An electromechanical hybrid multi-phase DC square wave motor with arcless commutation - Google Patents

Abstract

The present invention discloses an electromechanical hybrid arcless-commutation multiphase direct-current square-wave motor. The mechanical part of the multiphase direct-current square-wave motor includes electric brushes and a commutato; each phase of armature winding is led out through the electric brushes; the commutator comprises one or more commutator segment groups, wherein one of thecommutator segment groups is composed of a power source positive pole commutator segment, a freewheeling commutator segment I, a power source negative pole commutator segment and a freewheeling commutator sheet II; the power source positive pole commutator segment, the freewheeling commutator segment I, the power source negative pole commutator segment and the freewheeling commutator sheet II are insulated from one another through mica sheets and are circumferentially distributed into a complete 360-degree electrical angle cycle, and the mechanical angle of each of the power source positive pole commutator segment, the freewheeling commutator segment I, the power source negative pole commutator segment and the freewheeling commutator sheet II is 360 degrees/P; the electrical angle of each power source positive pole commutator segment and each power source negative pole commutator segment is 120 degrees, and the mechanical angle of each power source positive pole commutator segment and each power source negative pole commutator segment is 120 degrees/P; the electrical angle of each of the freewheeling commutator segment I, the freewheeling commutator sheet II as well as insulation mica sheets in front of and behind the freewheeling commutator segment I and the freewheeling commutator sheet II is 60 degrees, and the mechanical angle of each of the freewheeling commutator segment I, the freewheeling commutator sheet II as well as the insulation mica sheets in front of and behind the freewheeling commutator segment I and the freewheeling commutator sheet II is 60 degrees/P; and the commutator is fixed at a stator side according to the positions of magnetic poles and is shared by all the windings.

Description

An electromechanical hybrid multi-phase DC square wave motor with arcless commutation

technical field

The invention relates to the technical field of motor design and manufacture, in particular to an electromechanical hybrid multi-phase DC square wave motor with arcless commutation.

Background technique

At present, traditional DC motors use a mechanical commutation device consisting of a commutator and brushes to realize commutation. voltage and sparks are generated. In addition, in order to prevent arcing during commutation and cause ring fire failures, the voltage between the commutator plates must be limited to less than ten volts, so the number of commutator plates is large, resulting in complex structure of the commutator and high cost. Difficult DC motors usually also require commutation poles or auxiliary commutation brushes, further increasing costs. Due to the almost inevitable existence of sparks and the possibility of arcing in traditional mechanical commutation devices, as well as the disadvantages of complex structure and high cost, brushless DC motors using electronic commutators emerged as the times require, but electronic commutators The system cost is increased, and the control is complicated, and the reliability is low in the case of strong electromagnetic interference.

Chinese invention patent CN1455500A "Power supply commutation device for multi-phase DC motor" proposes a power supply commutation device, which uses mechanical and electronic hybrid commutation, does not require additional controllers and power electronic converters, and tries to solve the traditional The arc and spark problems in the mechanical commutation device, but the actual effect shows that it is difficult to suppress the commutation arc and spark, and each phase winding in this commutation device is equipped with a commutator, which requires more commutation segments and diodes. flow bridge arm.

Therefore, it is desired to have an electromechanical hybrid arcless commutated multi-phase DC square wave motor that can overcome or at least alleviate the above-mentioned defects of the prior art.

Contents of the invention

The object of the present invention is to provide an electromechanical hybrid arcless commutated multi-phase DC square wave motor to overcome the above-mentioned problems in the prior art.

In order to achieve the above object, the present invention provides an electromechanical hybrid multi-phase DC square-wave motor with arcless commutation, the mechanical part of the multi-phase DC square-wave motor commutation device includes: brushes and commutators, each phase The armature winding is drawn out through the brush, and the commutator includes one or more commutator segments, one of which consists of the positive commutator segment of the power supply, the freewheeling commutator segment I, the negative commutator segment of the power supply and the freewheeling commutator segment. They are insulated from each other by mica sheets, and are arranged in a complete 360° electrical angle cycle according to the circumference, occupying a mechanical angle of 360°/P, each power supply positive commutator and power supply negative commutator The electrical angle is 120°, the mechanical angle is 120°/P, the electrical angle of each freewheeling commutator I, freewheeling commutator II and its front and rear insulating mica sheets is 60°, and the mechanical angle is 60°/P. The commutator is fixed on the stator side according to the magnetic pole position, and all windings share one.

Preferably, the brushes rotate with the rotor of the commutation device.

Preferably, the mechanical angle difference between the adjacent brushes is 360°/m.

Preferably, the commutation device of the multi-phase DC square wave motor also includes a freewheeling buffer circuit, the freewheeling buffer circuit includes a buffer capacitor and two freewheeling bridge arms, each freewheeling bridge arm is composed of three diodes, The positive commutator of the power supply is connected to the positive pole of the DC power supply, the negative commutator of the power supply is connected to the negative pole of the DC power supply, and the freewheeling commutator I and the freewheeling commutator II are respectively connected to the midpoint of a freewheeling bridge arm of a diode .

Preferably, the freewheeling buffer circuit has one or more sets.

Preferably, the number of commutator segments included in the commutator should be equal to the number of permanent magnet pole pairs, and the positive and negative commutator segments of the power supply face the N and S poles of the permanent magnets respectively.

Preferably, the width of the brushes needs to be greater than the width of the mica insulation sheets between the commutator segments.

In order to overcome the deficiencies of the existing DC motor commutation devices, especially the problems of commutation arcs and sparks, commutation plates and freewheeling bridge arm redundancy in the power reversing device, the present invention proposes an electromechanical hybrid arcless commutation The multi-phase direct current square wave motor, the motor commutation device will not produce arcs, and significantly reduce the commutation sparks, the number of required commutation pieces is small, the commutator is simple in structure, low in cost, and the electromechanical motor of the present invention The multi-phase DC square-wave motor with hybrid arcless commutation does not require additional controllers and power electronic converters, which saves system costs; all the windings of the multi-phase DC square-wave motor with electromechanical hybrid arcless commutation of the present invention share one Compared with the power commutator in the prior art, the commutator greatly reduces the number of commutator segments and diode freewheeling bridge arms when the number of phases is large, which is easy to be extended to multi-phase motors and has broad application prospects.

Description of drawings

Figure 1 is the electrical connection diagram of the electromechanical hybrid arcless commutation device and armature winding of a three-phase bipolar DC motor.

Fig. 2 is a longitudinal sectional structural view of an embodiment of a three-phase bipolar DC motor.

Fig. 3 is a sectional view taken along line A--A of Fig. 2 .

FIG. 4 is an expanded view of the commutator 2 in FIG. 2 along the circumferential direction.

Fig. 5 is an electrical connection diagram of an electromechanical hybrid arcless commutation device and an armature winding of a three-phase four-pole DC motor.

Figure 6. Schematic diagram of the three-phase current and the freewheeling buffer capacitor voltage when the three-phase DC motor is working in the electric state.

detailed description

In order to make the objectives, technical solutions and advantages of the present invention clearer, the technical solutions in the embodiments of the present invention will be described in more detail below in conjunction with the drawings in the embodiments of the present invention. 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 invention. The embodiments described below by referring to the figures are exemplary and are intended to explain the present invention and should not be construed as limiting the present invention. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without creative efforts fall within the protection scope of the present invention. Embodiments of the present invention will be described in detail below in conjunction with the accompanying drawings.

In a broad embodiment of the present invention: the mechanical part of the multi-phase DC square wave motor commutation device includes: a brush and a commutator, each phase of the armature winding is drawn through the brush, and the commutator includes one or more Commutator segment group, one of which is composed of positive commutator segment of power supply, freewheeling commutator segment I, negative commutator segment of power supply and freewheeling commutator segment II, which are insulated from each other by mica sheet, according to the circumference Arranged into a complete 360° electrical angle cycle, occupying a mechanical angle of 360°/P, the electrical angle of each power supply positive commutator piece and the power supply negative pole commutator piece is 120°, and the mechanical angle is 120°/P. A freewheeling commutator I, freewheeling commutator II and its front and rear insulating mica sheets have an electrical angle of 60° and a mechanical angle of 60°/P. The commutator is fixed on the stator side according to the magnetic pole position, and all windings share one.

Based on the structure of m-phase armature winding and P pair pole brushless DC motor, the air gap magnetic field and electromotive force are trapezoidal waves, and the armature current is square wave, but the stator and rotor are inverted, and the stator is P pair of permanent magnet poles. The rotor is a star-connected m-phase armature winding.

The normal operation of the electromechanical hybrid arcless reversing device needs to meet four principles:

First, the principle of constant electromagnetic torque: In order to ensure constant electromagnetic torque, the number of commutator segments included in the commutator should be equal to the number of permanent magnet pole pairs, and the positive and negative commutator segments of the power supply are respectively facing the N, S pole.

Second, the principle of the uniqueness of the state of the freewheeling buffer circuit: In order to ensure the uniqueness of the working state of the freewheeling buffer circuit, each set of freewheeling buffer circuit can only be connected to one phase winding at any time, and the situation of connecting multi-phase windings may include : Multiphase windings are directly connected to the same freewheeling commutator; multiphase windings are connected to the freewheeling bridge arm through different groups of freewheeling commutator connected to the same freewheeling bridge arm; multiphase windings are connected to the freewheeling bridge arm through the same set of freewheeling buffer circuit Different freewheeling bridge arms are connected to the set of freewheeling buffer circuits.

In order to avoid that the phase windings are directly connected to the same freewheeling commutator, the mechanical angle between two adjacent brushes needs to be greater than the mechanical angle of the freewheeling commutator, and the mechanical angle of the freewheeling commutator can be compressed by increasing the number of pole pairs, or Reduce the number of phases, thereby increasing the mechanical angle between two adjacent brushes to achieve. For a DC motor with m-phase and P opposite poles, there are m brushes, and the mechanical angle difference between two adjacent brushes is 360°/m. The mechanical angle of the freewheeling commutator is 60°/P, and there should be 360°/m>60°/P, that is, P>m/6. For the critical situation of P=m/6, the width of the freewheeling commutator should be appropriately reduced so that the distance between it and the power commutator, that is, the width of the mica insulating sheet is greater than half of the width of the brush can avoid contact with the multi-phase winding connect.

In order to prevent the multi-phase winding from being connected to the freewheeling bridge arm through different groups of freewheeling commutator segments connected to the same freewheeling bridge arm, it is necessary to comprehensively consider the number of phases and pole pairs to determine the corresponding freewheeling commutator in each commutator segment group. Whether the slices are connected to the same freewheeling bridge arm, so as to obtain the required number of freewheeling buffer circuit sets. When the number of winding phases is fixed and only the number of pole pairs is increased, the corresponding freewheeling commutator segments in each commutator segment group can be connected to the same freewheeling bridge arm, and no additional freewheeling buffer circuit is required at this time. When the corresponding freewheeling commutator segments in each commutator segment group need to be connected to different freewheeling bridge arms, the most required freewheeling buffer circuits are P sets.

In order to prevent multi-phase windings from being connected to the set of freewheeling snubber circuits through different freewheeling bridge arms of the same set of freewheeling snubber circuits, the mechanical angle between two adjacent brushes cannot be within the range of 120°/P to 240°/P. For the critical situation where the mechanical angle between the two brushes is equal to 120°/P and 240°/P, the width of the freewheeling commutator can also be appropriately reduced to make the distance from the power commutator, that is, the width of the mica insulating sheet is greater than half of the brush width to avoid connection with multi-phase windings.

Third, the principle of non-suspended windings: In order to ensure that the winding can be connected to the next commutator segment before it is completely separated from the current commutator segment, that is, no winding is suspended at any time, the width of the brush must be greater than the width of the mica insulation sheet between the commutator segments .

Fourth, the principle of capacitor selection: the generation of arc must meet the dielectric breakdown field strength conditions (arcing electric field strength conditions) and arcing voltage conditions at the same time. Due to the function of the buffer capacitor, after the brushes in contact with the freewheeling commutator are separated from the power commutator, the voltage between the two begins to rise slowly. When the distance is extremely small, the electric field intensity is still relatively large, and the arcing electric field intensity The condition is satisfied, but the arcing voltage condition is not satisfied, so no arc will be generated; as the distance increases, the arcing voltage condition has been met, but the electric field strength condition is no longer satisfied, and no arc will be generated. The threshold electric field strength E _T = 5×10 ⁵ V/m is desirable, which is far lower than the air breakdown field strength of 3×10 ⁶ V/m under standard atmospheric pressure in the high voltage theory, which can ensure an electric field strength lower than E _T Will not break down the brush and power commutator gap.

In order to suppress arcing during the freewheeling process, the electric field strength between the brush and the power commutator should be lower than the threshold electric field strength. Given a minimum arc-free speed, the threshold electric field strength is multiplied by the linear speed of the brush at this speed It is the rate of change of the non-arcing voltage, and the minimum value of the capacitance is calculated according to the rate of change of the voltage to ensure that no arc occurs. At the highest speed, in order to ensure that the freewheeling process ends within the freewheeling stage at an electrical angle of 60°, the capacitor needs to be fully discharged within this time period, and the maximum value of the capacitor is calculated according to this time.

According to the above four principles, the structure of the electromechanical hybrid arcless commutation device of the DC motor with any number of phases and any number of pole pairs can be determined.

As shown in the embodiment of the three-phase two-pole DC motor in Fig. 1, the commutation is realized by the electromechanical hybrid arcless commutation device composed of the brush 1, the commutator 2 and the freewheeling buffer circuit. The rotor armature is a star-connected three-phase symmetrical winding A, B, C, each phase winding is drawn out through a brush 1 rotating with the rotor, and two adjacent brushes 1 have a mechanical angle difference of 120°. The commutator 2 only includes one commutator segment group, which is composed of the positive commutator segment 3 of the power supply, the freewheeling commutator segment I4, the negative commutator segment 5 of the power supply and the freewheeling commutator segment II6 to form a complete circle, passing through each other The mica sheet 7 is insulated and fixed on the stator 11, and the positive pole commutation piece 3 and the negative pole commutation piece 5 of the power supply are respectively facing the N and S poles of the permanent magnet. In the case of two poles, the electrical and mechanical angles of the positive commutator 3 and the negative commutator 5 of the power supply are both 120°, and the freewheeling commutator I4, the freewheeling commutator II6 plus the front and rear insulating mica sheets 7 The electrical and mechanical angles are both 60°. The electronic part of the commutation device is composed of a freewheeling buffer circuit, including a buffer capacitor C and two freewheeling bridge arms. The freewheeling bridge arm I is composed of diodes D ₁ , D ₂ and D ₅ , and the freewheeling bridge arm II Consists of diodes D ₃ , D ₄ and D ₆ . The positive commutator piece 3 of the power supply is connected to the positive pole U ₊ of the DC power supply, the negative pole commutator piece of the power supply is connected to the negative pole U _- of the DC power supply, and the freewheeling commutator piece I and the freewheeling commutator piece II are respectively connected to the midpoint of the freewheeling bridge arm I and II .

In Fig. 2, the electromechanical hybrid DC motor with arcless commutation is mainly composed of brushes 1, commutator 2, rotor 8, shaft 9, disk 10 for fixing brushes, stator 11 and freewheeling buffer circuit 12. Wherein, the commutator 2 is fixed on the stator 7, and the positive pole commutator piece 3 and the negative pole commutator piece 5 are respectively facing the N and S poles of the permanent magnet, and the freewheeling buffer circuit 12 is also fixed on the stator 7, and the brush 1 is fixed on the disc 10, and the disc 10 is fixed on the rotor 8 and rotates together, thereby driving the brush 1 to rotate and realizing the sliding contact between the brush 1 and the commutator 2. As shown in FIG. 3 , the brushes 1 are equally spaced on the disk 10 , and two adjacent brushes 1 have a mechanical angle difference of 120°. The commutator 2 is fixed on the inner peripheral surface of the stator 7, and four commutator segments form a complete circle. FIG. 4 is a schematic diagram of the commutator 2 deployed in the circumferential direction.

For a three-phase two-pole DC motor, the two adjacent brushes 1 have a mechanical angle difference of 120°, and the commutator has only one commutator segment set, the freewheeling commutator I4 and the freewheeling commutator II6 plus the front and rear insulating mica sheets The mechanical angle of 7 is 60°. At any time, each freewheeling commutator is directly connected to at most one phase winding; the commutation device only needs a set of freewheeling buffer circuit, and each freewheeling bridge arm is only connected to one freewheeling For the commutator segment, the multi-phase winding will not be connected to the freewheeling bridge arm through different groups of freewheeling commutator segments connected to the same freewheeling bridge arm; for the critical situation where the mechanical angle between the two brushes is equal to 120°, the The width of the freewheeling commutator is to make the distance between it and the power commutator, that is, the width of the mica insulating sheet 7 is greater than half of the width of the brush 1, and the multi-phase winding will not be connected to the same set of freewheeling buffer through different freewheeling bridge arms circuit. Therefore, the reversing device satisfies the principle of constant electromagnetic torque and the principle of unique state of freewheeling buffer circuit. At the same time, the width of the brush 1 is greater than the width of the mica insulating sheet 7 between the commutator plates, so the principle of not floating the winding is satisfied.

When the DC motor is running normally in the electric state, the armature winding is in sliding contact with the positive commutator piece 3 of the power supply, the freewheeling commutator piece I4, the negative pole commutator piece 5 of the power supply, and the freewheeling commutator piece II6 through the brush 1, and then again Reach the power supply positive commutator piece 3 and start the next cycle. The sliding contact between the brush 1 and the commutator 2 realizes the commutation of the armature winding current. In one cycle, the armature winding has forward conduction, forward freewheeling, reverse conduction, reverse freewheeling and after freewheeling. Non-conductive five states. As shown in the position of brush 1 in Figure 1, the voltage of capacitor C at the current moment is the DC power supply voltage, the C-phase winding conducts forwardly, the B-phase winding begins to conduct in reverse, and the A-phase winding just leaves the negative commutator piece 5 of the power supply to start reverse freewheeling , the diode D ₆ is turned on, and the capacitor C starts to discharge in the forward direction. After the forward discharge is completed, the diode D ₆ is turned off, and the A-phase current flows directly into the positive pole of the power supply through the diode D ₃ . _Zero ; until phase C starts to continue to flow forward, diode _{D5 conducts} , and capacitor C starts to charge forward. After the flow is completed, the voltage of the capacitor C remains at the DC power supply voltage. The windings of each phase alternate forward and reverse freewheeling, and the capacitor C is charged and discharged in a cycle.

When the applied DC power supply voltage is lower than the electromotive force of the armature winding, the DC motor works in a braking state. As shown in the position of brush 1 in Figure 1, the C-phase winding conducts in the reverse direction, the B-phase winding conducts forward, and the A _- phase winding just leaves the negative commutator piece 5 of the power supply and starts to continue to flow in the forward direction. The winding provides a freewheeling channel; when C is reversely freewheeling, the anode of the DC power supply provides _a freewheeling channel for it through diode D1.

The generation of arc needs to meet the condition of dielectric breakdown field intensity (arcing electric field intensity condition) and arcing voltage condition at the same time. Due to the effect of the buffer capacitor C, after the brush 1 in contact with the freewheeling commutator is separated from the power commutator, the voltage between the two begins to rise slowly. When the distance is extremely small, the electric field intensity is still large, and arcing The electric field strength condition is satisfied, but the arcing voltage condition is not satisfied, so no arc will be generated; as the distance increases, the arcing voltage condition has been met, but the electric field strength condition is no longer satisfied, and no arc will be generated. The threshold electric field strength E _T = 5×10 ⁵ V/m is desirable, which is far lower than the air breakdown field strength of 3×10 ⁶ V/m under standard atmospheric pressure in the high voltage theory, which can ensure an electric field strength lower than E _T The gap between the brush 1 and the power commutator will not be broken down.

In order to suppress arcing during the freewheeling process, the electric field strength between the brush 1 and the power commutator should be lower than the threshold electric field strength E _T , given a minimum arc-free speed n _min , the threshold electric field strength E _T multiplied by the brush The linear velocity at this rotational speed is the rate of change of the non-arcing voltage, and the minimum capacitance value C _min is calculated according to the rate of change of the voltage to ensure no arc generation. The calculation formula is as follows:

Among them: i _min is the current of the armature winding at the lowest speed, r is the radius of the inner circle of the commutator.

At the highest speed n _max , in order to ensure that the freewheeling process ends within the freewheeling phase at an electrical angle of 60°, the capacitor C needs to be fully discharged within this time period. The formula for estimating the duration of the freewheeling process Δt _max is:

According to the time Δt _max , the calculation formula for calculating the maximum capacitance C _max is obtained:

Among them: u _max and i _max are the voltage and current of the armature winding at the highest speed, and L is the inductance of the armature winding. According to formula (1) and formula (3) the capacitance value calculated meets the capacitance selection principle.

The electrical connection diagram of the electromechanical hybrid arcless commutation device and armature winding of a three-phase four-pole DC motor shown in Figure 5. The mechanical angle difference between two adjacent brushes 1 is 120°. The commutator has two commutator segments. The mechanical angle of the power commutator segments is 60°. The angle is 30°, and each freewheeling commutator segment is directly connected to at most one phase winding at any time; the commutation device only needs one set of freewheeling buffer circuit, and each freewheeling bridge arm is connected to two sets of commutator segments The corresponding two freewheeling commutator pieces, and the multi-phase winding will not be connected to the freewheeling bridge arm through these two freewheeling commutator pieces; for the critical situation where the mechanical angle between the two brushes 1 is equal to 120°, the appropriate reduction The width of the freewheeling commutator is reduced to make the distance between it and the power supply commutator, that is, the width of the mica insulating sheet 7 is greater than half the width of the brush, and the multi-phase windings will not be connected to the same set of freewheeling bridge arms through different freewheeling bridge arms. snubber circuit. Therefore, the reversing device satisfies the principle of constant electromagnetic torque and the principle of unique state of freewheeling buffer circuit. At the same time, the width of the brush 1 is greater than the width of the mica insulating sheet 7 between the commutator plates, so the principle of not floating the winding is satisfied. According to formula (1) and formula (3) calculate capacitance value to satisfy the principle of electric capacity selection.

As shown in Figure 6, the schematic diagram of the three-phase current and capacitor voltage when the DC motor is working in the electric state, each phase is sequentially circulated in the forward conduction 120° electrical angle, the forward freewheeling and non-conduction 60° electrical angle, and the reverse conduction 120° electrical angle Angle, reverse freewheeling and non-conduction 60° electrical angle, A, B, C three mutual difference of 120° electrical angle. Capacitor C starts to charge from zero voltage when there is positive freewheeling of the winding, and maintains it after reaching the DC power supply voltage, until it starts to discharge when there is reverse continuous current of the winding, and maintains zero voltage after the discharge is completed, until the next forward freewheeling charge.

Finally, it should be pointed out that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit them. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that: they can still modify the technical solutions described in the aforementioned embodiments, or perform equivalent replacements for some of the technical features; and these The modification or replacement does not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims (7)

1. a multiphase direct current square wave motor of electromechanical hybrid arcless commutation, characterized in that, the mechanical part of the multiphase direct current square wave motor commutation device comprises: electric brush and commutator, each phase armature winding Lead out through the brush, the commutator contains one or more commutator segment groups, one of which consists of power supply positive commutator segment, freewheeling commutator I, power supply negative commutator segment and freewheeling commutator II Composition, they are insulated from each other by mica sheets, arranged in a complete 360° electrical angle cycle according to the circumference, occupying a mechanical angle of 360°/P, the electrical angle of each power supply positive commutator and power supply negative commutator is 120°, the mechanical angle is 120°/P, the electrical angle of each freewheeling commutator I, freewheeling commutator II and its front and rear insulating mica sheets is 60°, and the mechanical angle is 60°/P, the commutator It is fixed on the stator side according to the magnetic pole position, and all windings share one. 2. The electromechanical hybrid multi-phase DC square wave motor with arcless commutation according to claim 1, wherein the brushes rotate with the rotor of the commutation device. 3. The electromechanical hybrid multi-phase DC square wave motor with arcless commutation according to claim 2, characterized in that: the mechanical angle difference between the adjacent brushes is 360°/m. 4. The polyphase DC square wave motor of electromechanical hybrid arcless commutation as claimed in claim 1, characterized in that: the commutation device of said polyphase DC square wave motor also includes a freewheeling buffer circuit, and the freewheeling buffer circuit It includes a buffer capacitor and two freewheeling bridge arms, each freewheeling bridge arm is composed of three diodes, the positive commutator piece of the power supply is connected to the positive pole of the DC power supply, and the negative pole commutator piece of the power supply is connected to the negative pole of the DC power supply. Freewheeling commutator I and freewheeling commutator II are respectively connected to the midpoint of a freewheeling bridge arm of a diode. 5. The electromechanical hybrid multi-phase DC square wave motor with arcless commutation according to claim 4, characterized in that: the number of the freewheeling buffer circuits is one or more. 6. The electromechanical hybrid multi-phase direct current square wave motor with arcless commutation as claimed in claim 1, characterized in that: the number of commutator segments included in the commutator should be equal to the number of pole pairs of permanent magnets, and the power supply is positive , and the negative commutator are facing the N and S poles of the permanent magnet respectively. 7. The electromechanical hybrid multi-phase DC square wave motor with arcless commutation according to claim 1, characterized in that: the width of the brushes needs to be greater than the width of the mica insulating sheets between the commutating plates.