A magnetoresistive motor and a control method thereof applied to a new energy vehicle

Abstract

This invention provides a reluctance motor and its control method for use in new energy vehicles. The motor includes a housing, with several stators fixed to the inner wall of the housing. A rotor is installed inside the cavity of the housing, and a rotating shaft is fixed to the center line of the rotor. A rear end cover and a front end cover are respectively installed at both ends of the housing. The rotating shaft passes through a central hole in the front end cover and extends out of the front end cover. The rotor is a magnetic conductor and has windings wound on it. This invention eliminates the need for permanent magnets, reducing production costs; it offers a wide and precise control range, improving motor performance; it suppresses the pulsation characteristics of switched reluctance motors; it allows for convenient measurement of motor status; and it combines the power generation and controllability of induction motors with the high speed and low heat generation of switched reluctance motors.

Description

Technical Field

[0001] This invention relates to a reluctance motor and its control method when applied to new energy vehicles. Background Technology

[0002] The automotive industry now widely uses permanent magnet synchronous motors (PMSM). PMSM uses permanent magnets to provide excitation, which makes the motor structure simpler, reduces processing and assembly costs, eliminates the need for excitation current and excitation losses, and improves the efficiency and power density of the motor.

[0003] An electromagnetic induction motor (IM) is a type of motor that converts electromechanical energy through electromagnetic induction between the stator and rotor, inducing a current within the rotor. The rotor consists of a rotor core, rotor windings, and a shaft. The rotor core is also part of the main magnetic circuit and is typically made of stacked silicon steel sheets with a thickness of 0.5 mm. The core is fixed to the shaft or rotor support.

[0004] Unlike these two types of motors, the switched reluctance motor (SRM) has a rotor made of metal plates that are not magnetic. It uses the principle of minimizing the magnetic reluctance of the magnetic circuit by utilizing movable parts in the magnetic field. That is, the magnetic flux always closes along the path of least magnetic reluctance. The tangential tension is generated by the distortion of the magnetic field. Therefore, its structural principle requires that the magnetic reluctance of the magnetic circuit should change as much as possible when the rotor rotates.

[0005] The main control methods for SRM include turn-on angle, turn-off angle, phase current amplitude, and phase winding terminal voltage. Different control methods will be generated by controlling these parameters individually or in combination. The commonly used control methods are angle control (APC), current chopper control (CCC), and voltage control (VC).

[0006] 1. The characteristics of each control method are:

[0007] (1) The torque adjustment range is large; multiple motors can be energized simultaneously to increase the output torque of the motor and the torque ripple is small; it can achieve optimal efficiency control or optimal torque control. However, the angle control method is not suitable for low-speed conditions and is generally used when running at high speed.

[0008] (2) Current chopper control is suitable for low-speed and braking operation conditions. It can limit the growth of current peak and play a good and effective regulation role. Moreover, the torque is relatively stable and the torque pulsation of electric vehicle motor is generally significantly reduced compared with other control methods.

[0009] (3) Voltage chopper control adjusts the average voltage of the phase winding through PWM, indirectly regulating and limiting excessive winding current. It is suitable for speed regulation systems and has a fast dynamic response to load disturbances. This control is easy to implement and has a low cost; however, its disadvantages are that the conduction angle is always fixed, the power element switching frequency is high, the switching loss is large, and the phase current cannot be precisely controlled.

[0010] 2. Compared to electromagnetic induction motors, switched reluctance motors have the following advantages:

[0011] ① The rotor of the electric motor has no windings, and the stator windings are easy to install as a whole, resulting in a simple structure and low price.

[0012] ②The motor's rotor has no permanent magnets, allowing for a higher temperature rise. Since the windings are all on the stator, the motor is easy to cool, resulting in high efficiency and low losses.

[0013] ③ The direction of the motor torque is independent of the direction of the stator winding current. The direction of motor rotation can be controlled simply by controlling the sequence of energizing the phase windings. Therefore, the power converter circuit is simple and reliable.

[0014] ④ The rotor has a small moment of inertia and a high torque-to-inertia ratio, making it suitable for high-speed drives. In addition, the rotor does not generate significant heat, which extends the service life of the motor bearings.

[0015] ⑤ It has a wide speed range, flexible control, and is easy to achieve torque / speed characteristics for various special requirements.

[0016] ⑥ It has a small starting current, no inrush current phenomenon that occurs when electromagnetic induction motors start, large starting torque, good low-speed performance, and is suitable for frequent starting.

[0017] 3. The main disadvantages of switched reluctance motors are as follows:

[0018] ① The electromagnetic torque has large pulsations and will resonate at a certain frequency, which makes the noise and vibration of the switched reluctance motor large.

[0019] ②The energy conversion density of a switched reluctance motor is lower than that of an electromagnetic induction motor.

[0020] ③ When the number of phases of the motor is large, the number of main wiring connections is also large, and the main circuit of the motor is more complex.

[0021] The permanent magnets of permanent magnet synchronous motors (PMSMs) are mostly made of rare earth elements such as neodymium iron boron. Under low-speed, high-torque conditions, demagnetization will occur, leading to irreversible performance degradation of the motor, and the price is high.

[0022] Switched reluctance motors use materials that do not contain magnetic materials, which reduces manufacturing costs. They also do not require consideration of the direction of the permanent magnet flux linkage, making the control method simpler. However, due to their off-peak pulsation, the motor vibrates and reacts slowly.

[0023] This invention addresses the issue of adding coil windings to switched reluctance motors (SRMs) to reduce rotor pulsation. Under the control of rotor current, the motor can more quickly meet speed and torque requirements. It integrates the advantages of switched reluctance motors and induction motors, making the operation of SRMs more controllable and more modular in control compared to permanent magnet synchronous motors (PMSMs).

[0024] 1. Insert-type stator gaskets are complex to manufacture and difficult to install.

[0025] 2. The tilted magnetic poles have different layers between the two laminations, making manufacturing complex.

[0026] 3. Switching devices with independent control of polar current are costly and generate negative torque, resulting in low system efficiency.

[0027] The motor disclosed in publication number CN102388524A is a motor with multiple magnetic field source stators. It includes a motor composed of electromagnetic excitation and / or permanent magnet excitation to reduce magnetic circuit losses. However, when the magnetic flux is conducted through the magnetic conductor, the motor rotor will generate heat loss, which limits the motor efficiency. Summary of the Invention

[0028] To address the aforementioned technical problems, this invention provides a reluctance motor and its control method when applied to new energy vehicles.

[0029] The present invention is achieved through the following technical solutions.

[0030] The present invention provides a reluctance motor; comprising a housing, a plurality of stators fixed on the inner wall of the housing, a rotor installed in the cavity of the housing, a rotating shaft fixed on the center line of the rotor, a rear end cover and a front end cover respectively installed at both ends of the housing, the rotating shaft passing through the central hole on the front end cover and extending out of the front end cover, the rotor being a magnetic conductor and having windings wound on the rotor.

[0031] The rotor includes slotted plates and rotor plates. The rotor plates are several plates stacked together as a whole. The slotted plate is one plate sandwiched between any two rotor plates.

[0032] The grooved platen and the rotor platen are machined with a central hole in the middle. Several pole pieces are uniformly fixed to the circumference of the central hole of the rotor platen. The two sides of the pole pieces are parallel to each other, and the outer ends of the two sides are machined with symmetrical grooves.

[0033] The electrode end face of the grooved plate is machined with a radial wire groove along the radial direction of the rotor. One end of the radial wire groove is connected to the central hole and the other end is closed. The electrode is also machined with a second wire exit groove and a first wire exit groove. The first wire exit groove and the second wire exit groove are respectively on both sides of the radial wire groove and are respectively on the same plane as the two side walls of the wire groove.

[0034] The rotating shaft has a wiring hole machined along its center line at one end near the rear end cover, and a wire through hole is also machined on the side wall of the wiring hole.

[0035] A method for controlling a reluctance motor in a new energy vehicle, wherein the vehicle enters the following cyclic steps after startup:

[0036] (1) Determine whether the vehicle is on a slope and in a parked state;

[0037] (2) When the brake pedal is released but the power pedal is not activated, if the vehicle is on a slope, the motor output torque is controlled to keep the motor angle at 0; if the vehicle is not on a slope, the motor output is used to make the vehicle enter a creeping state.

[0038] (3) When the power pedal is detected to be in motion, the motor stator is energized and the motor rotor is energized according to the timing sequence, and the vehicle speed is increased to speed a;

[0039] (4) When the vehicle speed increases to a, determine whether the power pedal and brake pedal are activated:

[0040] When the power pedal is activated, the motor stator circuit is energized, the motor rotor circuit is disconnected, and the energy storage capacitor is charged.

[0041] When the brake pedal is detected, the motor stator circuit is de-energized, and the motor rotor circuit is energized.

[0042] If the vehicle speed is greater than 'a' and the brake pedal action is detected, the force of the brake pedal action is determined. If the force is small, both the motor rotor and stator circuits are energized. The rotor circuit is disconnected according to the timing sequence, and the energy storage capacitor discharges to recover energy. If the force is large, energy is recovered through mechanical braking.

[0043] The motor stator circuit and the motor rotor circuit each include a stator single-pole control circuit and a rotor single-pole control circuit, which are connected in parallel with the power supply POWER.

[0044] The rotor single-pole control circuit includes a capacitor C and a switch S5 connected in series. The two ends of the series connection between capacitor C and switch S5 are respectively connected to switches S4 and S2. The other ends of switches S4 and S2 are respectively connected to the windings of the motor. The end of switch S4 connected to capacitor C is also connected to the positive terminal of diode D4. The two ends of switch S2 are also connected to the negative terminals of diode D4 and diode D2 respectively. The two ends of switch S4 are also connected to the positive terminals of diode D4 and diode D2 respectively.

[0045] The stator control circuit includes switches S1 and S3. Switches S1 and S3 are respectively connected to the positive and negative terminals of the single-pole power supply POWER and any winding of the motor. The two ends of switch S1 are also connected to the negative terminals of diodes D1 and D3, respectively, and the two ends of switch S3 are also connected to the positive terminals of diodes D1 and D3, respectively.

[0046] The speed a is 30 km / h.

[0047] The beneficial effects of this invention are as follows: it utilizes a motor composed of a non-permanent magnet magnetic conductor and electromagnetic excitation, and uses reluctance rotation to solve the problems of torque pulsation and control difficulties in switched reluctance motors; moreover, it does not generate significant heat and does not cause magnet demagnetization, thus improving motor efficiency and extending the service life of motor bearings; it achieves energy recovery by controlling the motor's operation mode, and possesses the characteristics of induction motors (generating and controllable power) and switched reluctance motors (high speed and no heat generation). Attached Figure Description

[0048] Figure 1 This is a schematic diagram of the structure of the present invention;

[0049] Figure 2 This is a schematic diagram of the grooved tablet pressing structure of the present invention;

[0050] Figure 3 This is a schematic diagram of the rotor pressing structure of the present invention;

[0051] Figure 4 This is a schematic diagram of the internal structure of the rotating shaft of the present invention;

[0052] Figure 5 This is a schematic diagram of the motor operating principle of the present invention;

[0053] Figure 6 This is a schematic diagram of the stable acceleration process of the present invention;

[0054] Figure 7 This is a schematic diagram of the low-speed braking process of the present invention;

[0055] Figure 8 This is a schematic diagram of the motor energy recovery process of the present invention;

[0056] Figure 9 This is a schematic diagram of the control system principle of the present invention;

[0057] Figure 10 This is a graph showing the inductance and current generation cycle of the present invention;

[0058] Figure 11 This is a schematic diagram of the controller circuit of the present invention;

[0059] Figure 12 This is a flowchart illustrating the working logic of the motor in an automobile according to the present invention.

[0060] In the diagram: 1-housing, 2-rear end cover, 3-front end cover, 4-shaft, 41-wiring hole, 42-threading hole, 5-positioning pin, 6-wire slot pressing plate, 61-radial wiring slot, 62-first wire outlet slot, 63-second wire outlet slot, 7-rotor pressing plate, 71-pole plate, 72-wire slot, 73-center hole, 8-winding, 9-stator. Detailed Implementation

[0061] The technical solution of the present invention is further described below, but the scope of protection is not limited to what is described.

[0062] A reluctance motor includes a housing 1, a plurality of stators 9 fixed on the inner wall of the housing 1, a rotor installed in the cavity of the housing 1, a rotating shaft fixed on the center line of the rotor, a rear end cover 2 and a front end cover 3 respectively installed at both ends of the housing 1, the rotating shaft 4 passing through the center hole on the front end cover 3 and extending out of the front end cover 3, the rotor being a magnetic conductor and having windings wound on the rotor.

[0063] The rotor includes a slotted plate 6 and a rotor plate 7. The rotor plate 7 consists of several plates stacked together. The slotted plate 6 is a single piece sandwiched between any two rotor plates 7.

[0064] The grooved plate 6 and the rotor plate 7 are machined with a central hole 73 in the middle. Several pole pieces 71 are uniformly fixed in the circumferential direction of the central hole 73 of the rotor plate 7. The two sides of the pole pieces 71 are parallel to each other, and the outer ends of the two sides are machined with symmetrical grooves 72.

[0065] The end face of the electrode plate 71 of the grooved plate 6 is machined with a radial groove 61 along the radial direction of the rotor. One end of the radial groove 61 is connected to the central hole 73, and the other end is closed. The electrode plate 71 is also machined with a second wire outlet groove 63 and a first wire outlet groove 62. The first wire outlet groove 62 and the second wire outlet groove 63 are respectively on both sides of the radial groove 61 and are respectively on the same plane as the two side walls of the groove 72.

[0066] The rotating shaft 4 has a wiring hole 41 machined along its center line at one end near the rear end cover 2, and a wire through hole 42 is also machined on the side wall of the wiring hole 41.

[0067] A method for controlling a reluctance motor in a new energy vehicle, wherein the vehicle enters the following cyclic steps after startup:

[0068] (1) Determine whether the vehicle is on a slope and in a parked state;

[0069] (2) When the brake pedal is released but the power pedal is not activated, if the vehicle is on a slope, the motor output torque is controlled to keep the motor angle at 0; if the vehicle is not on a slope, the motor output is used to make the vehicle enter a creeping state.

[0070] (3) When the power pedal is detected to be in motion, the motor stator is energized and the motor rotor is energized according to the timing sequence, and the vehicle speed is increased to speed a;

[0071] (4) When the vehicle speed increases to a, determine whether the power pedal and brake pedal are activated:

[0072] When the power pedal is activated, the motor stator circuit is energized, the motor rotor circuit is disconnected, and the energy storage capacitor is charged.

[0073] When the brake pedal is detected, the motor stator circuit is de-energized, and the motor rotor circuit is energized.

[0074] If the vehicle speed is greater than 'a' and the brake pedal action is detected, the force of the brake pedal action is determined. If the force is small, both the motor rotor and stator circuits are energized. The rotor circuit is disconnected according to the timing sequence, and the energy storage capacitor discharges to recover energy. If the force is large, energy is recovered through mechanical braking.

[0075] The motor stator circuit and the motor rotor circuit each include a stator single-pole control circuit and a rotor single-pole control circuit, which are connected in parallel with the power supply POWER.

[0076] The rotor single-pole control circuit includes a capacitor C and a switch S5 connected in series. The two ends of the series connection between capacitor C and switch S5 are respectively connected to switches S4 and S2. The other ends of switches S4 and S2 are respectively connected to the windings of the motor. The end of switch S4 connected to capacitor C is also connected to the positive terminal of diode D4. The two ends of switch S2 are also connected to the negative terminals of diode D4 and diode D2 respectively. The two ends of switch S4 are also connected to the positive terminals of diode D4 and diode D2 respectively.

[0077] The stator control circuit includes switches S1 and S3. Switches S1 and S3 are respectively connected to the positive and negative terminals of the single-pole power supply POWER and any winding of the motor. The two ends of switch S1 are also connected to the negative terminals of diodes D1 and D3, respectively, and the two ends of switch S3 are also connected to the positive terminals of diodes D1 and D3, respectively.

[0078] The motor has windings at the end of the stator. Each winding on the stator is connected to a single-pole stator control circuit. The poles on each rotor are stacked to form a multi-pole rotor. Each pole is wound with a winding, and each winding is connected to a single-pole rotor control circuit.

[0079] like Figure 5As shown, this illustrates the working principle of a switched reluctance motor. When the rotor ① and stator ① are at position A1, the stator control circuit connected to stator ① energizes stator ①. Since the magnetic flux flows to the path of least magnetic resistance, rotor ① will rotate clockwise and its speed will continuously increase. When the rotor is about to reach position B1, the stator ① control circuit is disconnected, and rotor ① will rotate to position C1 due to inertia, and then rotate to the next electromagnetic pole, reaching the next electromagnetic pole A2. At this time, the stator control circuit connected to stator ② at A2 energizes stator ②, and rotor 2 continues to rotate.

[0080] like Figure 6 As shown, when the vehicle speed is below 30 km / h, the motor operates under stable acceleration conditions. When the rotor is in state A1, all single-pole stator control circuits are energized. Figure 11 When switches S1 and S3 are closed, the single-pole stator control circuit controls the rotor to be energized. Figure 11 When switches S2 and S4 are closed, the rotor can rotate normally. When the rotor is at the critical point B1 but has not reached the alignment position, the rotor circuit is disconnected. When the rotor just passes the B1 position, the rotor is energized, generating a force that repels the stator end, which cancels out the fluctuation caused by the decay of inertial force, and continues to push the rotor to rotate a certain angle. Then the power is cut off to reach the position of the next A2 state, thus achieving stable acceleration of the vehicle.

[0081] like Figure 7 As shown, when the vehicle speed is less than 30 km / h, under the condition of reduced rotational speed, when the rotor and stator are at position A1, the rotor winding and stator winding current switches are opened simultaneously. Due to the mutually repulsive magnetic forces, the rotor will rotate clockwise to decelerate. When the rotor is just at position B1, the rotor current switch is turned off while the stator current switch remains open. The rotor will decelerate due to the magnetic force and then return to the next electromagnetic pole, returning to position A2. Then, the rotor winding and stator winding current switches are opened simultaneously again. Due to the mutually repulsive magnetic forces, the rotor will rotate clockwise to decelerate, thus stabilizing and reducing the vehicle speed.

[0082] like Figure 8 As shown, the rotor circuit disconnects when the vehicle speed exceeds 30 km / h. Figure 11 When switch S5 is closed, the electrical energy generated during rotor rotation is stored in the energy storage capacitor C. This disconnection of the rotor winding not only improves the robustness of motor control under high-speed rotation, but also reduces the heat generated by the motor during high-speed rotation.

[0083] When a deceleration signal is received, the stator winding is de-energized, and the controllable capacitor and rotor winding circuit switches are opened simultaneously to supply power to the rotor. The stator winding will cut the magnetic field lines to generate electrical energy, and the motor stator will recover braking energy and store the current to the power source. At the same time, due to magnetic resistance, the rotor speed will decrease continuously and evenly.

[0084] Referring to the control method of switched reluctance motors, two signal receiving and processing terminals for current detection and position detection are designed on the controller control loop. The basic components are as follows: Figure 9 As shown.

[0085] Generally, the operation of an SRG includes two phases: the excitation cycle and the power generation cycle. Figure 10 As shown. When the switch is turned on, the phase current rises, and during excitation, electrical energy is stored in the magnetic field of the SRG. After the switch is turned off, the SRG is in power generation mode in the inductance drop region, and energy flows back to the power battery during power generation. Considering the voltage drop of the phase winding, the voltage balance equation can be expressed as:

[0086] (1)

[0087] in, and These are phase voltage, current, inductance, rotor angle, and angular velocity, respectively. Phase voltage is related to the voltage drop across the resistor caused by the change in inductance, the transformer electromotive force, and the back electromotive force. These three pressure drops are balanced.

[0088] Considering that the deceleration time is generally very short, the capacitor has sufficient energy storage time during excitation, and its operating efficiency is very high during power generation, we select any magnetic pole as an example and build a rough circuit model as follows. Figure 11 As shown,

[0089] Power provides power to the stator and rotor of a certain pole of the motor. L1 is the stator winding, L2 is the rotor winding, C is the rotor energy storage capacitor, S1, D1, S3, D3 are responsible for turning on the stator circuit switch, and S2, D2, S4, D4 are responsible for turning on the rotor circuit switch.

Claims

1. A control method of a reluctance motor applied to a new energy vehicle, comprising a shell (1), a plurality of stators (9) are uniformly fixed on the inner wall of the shell (1), a rotor is installed in the cavity of the shell (1), the center line of the rotor is fixed with a rotating shaft, the two ends of the shell (1) are respectively provided with a rear end cover (2) and a front end cover (3), the rotating shaft (4) passes through the center hole of the front end cover (3) and extends out of the front end cover (3), the rotor is a magnetic conductor, and the stator (9) and the rotor are both wound with windings. The rotor comprises a wire slot pressing sheet (6) and a rotor pressing sheet (7), the rotor pressing sheet (7) is a plurality of pieces and is stacked together as a whole, and the wire slot pressing sheet (6) is a piece and is clamped between the gaps of any two rotor pressing sheets (7). The wire slot pressing sheet (6) and the rotor pressing sheet (7) are both provided with a center hole (73) in the middle part, a plurality of pole pieces (71) are uniformly fixed on the circumference of the center hole (73) of the rotor pressing sheet (7), the two side edges of the pole piece (71) are parallel to each other, and the two side edges are provided with symmetric wire slots (72) at the outer ends. characterized in that The control method of the reluctance motor applied to the new energy vehicle comprises the following steps after the vehicle starts: (1) judging whether the vehicle is on a slope and in a parking state; (2) when it is detected that the brake pedal is released but the power pedal is not operated, if the vehicle is on a slope, the motor output torque is controlled to keep the rotation angle of the motor at 0; if the vehicle is not on a slope, the motor output is controlled to make the vehicle enter a crawling state; (3) when it is detected that the power pedal is operated, the motor stator is powered on, the motor rotor is powered on according to the time sequence, and the vehicle speed is increased to a speed a; (4) when the vehicle speed is increased to a, judging whether the power pedal and the brake pedal are operated: when it is detected that the power pedal is operated, the motor stator circuit is powered on, the motor rotor circuit is disconnected, and the energy storage capacitor is charged and connected; when it is detected that the brake pedal is operated, the motor stator circuit is powered on and disconnected, and the motor rotor circuit is powered on; when the vehicle speed is greater than a and it is detected that the brake pedal is operated, judging the operating force of the brake pedal, if the force is small, the motor rotor and the stator circuit are both powered on, the rotor circuit is disconnected according to the time sequence, and the energy storage capacitor is discharged to recover energy; if the force is large, the energy is recovered through mechanical braking.

2. The control method of claim 1, when the magnetorheological electric machine is applied to a new energy vehicle, characterized in that: A radial wire slot (61) is formed on the end face of the pole piece (71) of the wire slot pressing sheet (6) along the radial direction of the rotor, one end of the radial wire slot (61) is communicated with the center hole (73), and the other end is closed, a second wire outlet slot (63) and a first wire outlet slot (62) are further formed on the pole piece (71), and the first wire outlet slot (62) and the second wire outlet slot (63) are respectively on the two sides of the radial wire slot (61) and are respectively in the same plane as the two side walls of the wire slot (72).

3. The control method of claim 1, when the magnetorheological electric machine is applied to a new energy vehicle, characterized in that: A wire slot (41) is formed in the center line of the rotating shaft (4) close to the rear end cover (2), and a threading hole (42) is further formed in the side wall of the wire slot (41).

4. The control method of claim 1, wherein the magnetorheological electric machine is applied to a new energy vehicle. The motor stator circuit and the motor rotor circuit respectively comprise a stator single-pole control circuit and a rotor single-pole control circuit, and the stator single-pole control circuit and the rotor single-pole control circuit are connected in parallel with a power supply POWER. The rotor single-pole control circuit comprises a capacitor C and a switch S5 connected in series, two ends of the capacitor C and the switch S5 connected in series are respectively connected with a switch S4 and a switch S2, the other ends of the switch S4 and the switch S2 are respectively connected with windings of the motor, one end of the switch S4 and the capacitor C is further connected with the positive electrode of a diode D4, the two ends of the switch S2 are further respectively connected with the negative electrode of the diode D4 and the diode D2, the two ends of the switch S4 are further respectively connected with the positive electrode of the diode D4 and the diode D2; The stator single-pole control circuit comprises a switch S1 and a switch S3, the switch S1 and the switch S3 are respectively connected on the positive and negative electrode wiring of the single-pole power supply POWER and the windings of the motor, the two ends of the switch S1 are further respectively connected with the negative electrode of a diode D1 and a diode D3, the two ends of the switch S3 are further respectively connected with the positive electrode of the diode D1 and the diode D3.

5. The control method of claim 1, wherein the magnetorheological electric machine is applied to a new energy vehicle. The speed a is 30Km / h.

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