A permanent magnet brake and control method thereof

Abstract

The present invention provides a permanent magnet brake and a control method thereof. The control method of the permanent magnet brake comprises the following steps: a control unit receives an instruction and determines the instruction type; if it is a release instruction, a voltage power supply module applies a release voltage U1 to the excitation winding; a current acquisition module collects the real-time current of the excitation winding and calculates the current change slope; when the current change slope is less than or equal to a set first change slope, it is determined that the permanent magnet brake has completed the release; if it is a braking instruction, the voltage power supply module applies a braking voltage U2 to the excitation winding; the voltage acquisition module collects the real-time induced voltage of the excitation winding and calculates the induced voltage change slope; when the induced voltage change slope is less than or equal to a set second change slope, it is determined that the permanent magnet brake has completed the braking. The permanent magnet brake and the control method thereof provided by the present invention optimize the braking structure and method, and improve the safety and response performance.

Description

Technical Field

[0001] The present invention relates to the technical field of automobile braking, and in particular to a permanent magnet brake and a control method thereof. Background Art

[0002] Currently, electromagnetic brakes are usually controlled by setting a predetermined voltage or current target on the coil winding to achieve desired state control of the excitation winding portion of the electromagnetic brake.

[0003] In the prior art, only a fixed parameter boundary with a large margin is obtained through the overall performance data or test data of the product, and the unified control parameter is used to control the winding circuit of the electromagnetic brake. Signal acquisition or state judgment is not performed on the actual electromagnetic brake structure, and it is impossible to determine whether the release and engagement of the electromagnetic brake are truly achieved. In addition, the parameter control of the predetermined voltage or current target cannot cover the performance fluctuations caused by product production differences, environmental impacts, wear and aging, etc. The control has a failure range, control lag, and energy consumption cannot be optimized, which reduces the speed, safety, reliability, and economy of the product control. For users, it will also cause practical problems such as performance waste, high failure rate, short service life, and high power consumption. Summary of the invention

[0004] The embodiment of the present invention provides a permanent magnet brake and a control method thereof, which optimizes the braking structure, realizes the control of the magnetic conductive part through the total magnetic field of the permanent magnet and the excitation winding, and then realizes the braking and releasing of the permanent magnet brake; utilizes the influence of the movement of the structural components of the permanent magnet brake on the voltage and current characteristics of the excitation winding during the release and braking process, confirms the state of the permanent magnet brake through the change of the voltage and current slope of the excitation winding, and improves the safety performance and response performance.

[0005] A permanent magnet brake provided in an embodiment of the present invention comprises a brake unit and a control unit, wherein the brake unit comprises a rotating component and a fixed component coaxially sleeved on a transmission shaft, wherein the rotating component rotates with the transmission shaft, wherein the fixed component is fixedly connected to a vehicle body, wherein the fixed component comprises a fixing part, an excitation winding and a permanent magnet, wherein the excitation winding and the permanent magnet are mounted on the fixing part; wherein the control unit is connected to the excitation winding, wherein the control unit comprises a voltage supply module, a current acquisition module and a voltage acquisition module; wherein the voltage supply module outputs a voltage to the excitation winding, wherein the current acquisition module acquires a current of the excitation winding, and wherein the voltage acquisition module acquires a current of the excitation winding. induced voltage; the rotating component includes a sleeve, a release member and a magnetic conductive member, the sleeve is fixedly sleeved on the transmission shaft, the release member and the magnetic conductive member are arranged side by side outside the sleeve, the release member is fixedly connected to the sleeve, the magnetic conductive member is movably connected to the sleeve, the sleeve allows the magnetic conductive member to move axially along the sleeve and prevents the magnetic conductive member from rotating relative to the sleeve, and an elastic member is arranged between the magnetic conductive member and the release member; the fixed component is sleeved outside the sleeve and is located at one end close to the magnetic conductive member, a rolling member is arranged between the fixed component and the sleeve, and the rolling member allows the transmission shaft to drive the sleeve to rotate relative to the fixed component.

[0006] Preferably, the magnetic field generated by the excitation winding after being energized is opposite to the direction of the magnetic field of the permanent magnet; when the voltage output to the excitation winding is less than the first set voltage, the magnetic field of the excitation winding is much smaller than the magnetic field of the permanent magnet, and the total magnetic field of the excitation winding and the permanent magnet has a suction force on the magnetic conductive part that is greater than the elastic force of the elastic part, and the magnetic conductive part moves toward the fixed component until it is combined with the fixed component, thereby preventing the rotating component and the transmission shaft from rotating, thereby achieving braking; when the voltage output to the excitation winding is greater than the second set voltage and less than the third set voltage, the magnetic field of the excitation winding and the magnetic field of the permanent magnet cancel each other out, and the total magnetic field of the excitation winding and the permanent magnet has a suction force on the magnetic conductive part that is less than the elastic force of the elastic part, and the magnetic conductive part moves toward the release part until it is separated from the fixed component, allowing the rotating component and the transmission shaft to rotate, thereby achieving brake release.

[0007] Preferably, the first set voltage, the second set voltage and the third set voltage increase in sequence.

[0008] Preferably, the release member is made of a non-magnetic material, the magnetic conductive member is made of a ferromagnetic material, and the elastic member is a plate spring.

[0009] Based on the same concept, the present invention also provides a control method for the above-mentioned permanent magnet brake, comprising the following steps:

[0010] The control unit receives the instruction and determines the instruction type;

[0011] If it is a release command, the voltage supply module applies a release voltage U to the excitation winding. 1 ;

[0012] The current acquisition module collects the real-time current of the excitation winding and calculates the current change slope;

[0013] When the current change slope is less than or equal to a set first change slope, determining that the permanent magnet brake has completed release;

[0014] If it is a braking command, the voltage supply module applies a braking voltage U to the excitation winding. 2 ;

[0015] The voltage acquisition module collects the real-time induced voltage of the excitation winding and calculates the slope of the induced voltage change;

[0016] When the induced voltage change slope is less than or equal to a set second change slope, it is determined that the permanent magnet brake completes braking.

[0017] Preferably, the release voltage U 1 Greater than the second set voltage and less than the third set voltage, the magnetic field of the excitation winding and the magnetic field of the permanent magnet cancel each other out, the total magnetic field of the excitation winding and the permanent magnet exerts a suction force on the magnetic conductive part that is less than the elastic force of the elastic part, and the magnetic conductive part moves toward the release part until it is separated from the fixed component, allowing the rotating component and the transmission shaft to rotate, thereby completing the brake release.

[0018] Preferably, after calculating the current change slope, the method further includes:

[0019] Determine whether the current change slope suddenly changes. If so, it means that the magnetic conductive member starts to move toward the release member when the current change slope suddenly changes.

[0020] After the current change slope suddenly changes, the current change slope is compared with the set first change slope. If the current change slope is less than or equal to the set first change slope, it is determined that the magnetic conductive part is separated from the fixed component and the permanent magnet brake is released.

[0021] Preferably, the braking voltage U 2 is less than the first set voltage, the magnetic field of the excitation winding is much smaller than the magnetic field of the permanent magnet, the total magnetic field of the excitation winding and the permanent magnet has a suction force on the magnetic conductive part that is greater than the elastic force of the elastic part, and the magnetic conductive part moves toward the fixed component until it is combined with the fixed component, thereby preventing the rotating component and the transmission shaft from rotating, thereby completing braking.

[0022] Preferably, after calculating the voltage change slope, the method further includes:

[0023] Determine whether the slope of the induced voltage change suddenly changes. If so, it means that the magnetic conductive component starts to move toward the fixed component when the slope of the induced voltage change suddenly changes.

[0024] After the induced voltage change slope changes suddenly, the induced voltage change slope is compared with the set second change slope. If the induced voltage change slope is less than or equal to the set second change slope, it is determined that the magnetic conductive part is combined with the fixed component and the permanent magnet brake completes braking.

[0025] Preferably, the method further comprises the following steps:

[0026] The control unit receives a release instruction;

[0027] The voltage supply module applies a release voltage U to the excitation winding 1 ;

[0028] The current acquisition module collects the real-time current of the excitation winding and calculates the current change slope;

[0029] When the current change slope is less than or equal to a set first change slope, determining that the permanent magnet brake has completed release;

[0030] The voltage supply module applies a braking voltage U to the excitation winding. 2 ;

[0031] The voltage acquisition module collects the real-time induced voltage of the excitation winding and calculates the voltage change slope;

[0032] Determine whether the induced voltage change slope has a sudden change. If a sudden change occurs and the induced voltage change slope is less than or equal to a set third change slope, it indicates that the magnetic conductive component is in a critical combination state with the fixed component;

[0033] The voltage supply module applies the release voltage U to the excitation winding in turn. 1 and braking voltage U 2 , so that the magnetic conductive member switches between the release state and the critical engagement state until the control unit receives a braking command.

[0034] Compared with the prior art, the technical solution of the embodiment of the present invention has beneficial effects.

[0035] For example, the permanent magnet brake and control method provided by the present invention realize control of the magnetic conductive parts through the total magnetic field of the permanent magnet and the excitation winding, thereby realizing braking and releasing of the permanent magnet brake. The magnetic fields of the permanent magnet and the excitation winding are in opposite directions, so that the excitation winding can be braked by power-off and released by power-on. The influence of the movement of the structural components of the permanent magnet brake on the characteristics of the changing trend of the induced voltage and current of the excitation winding during the release and braking process is utilized, and the state of the permanent magnet brake is confirmed by the changes in the induced voltage and current slope of the excitation winding, thereby avoiding the influence of differences in circuit control parameters caused by factors such as product production performance deviations, environmental influences, and aging during use, thereby improving safety, reliability and response performance.

[0036] For another example, the permanent magnet brake and control method thereof provided by the present invention applies a release voltage U to the excitation winding in turn after power-on release. 1 and braking voltage U 2 , so that the magnetic member switches between the release state and the critical bonding state to maintain the unbraking state, compared with always applying the release voltage U 1 To keep the released state more energy-efficient. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 This is a schematic diagram of the application of a permanent magnet brake according to an embodiment of the present invention;

[0038] Figure 2 This is a schematic diagram of the structure of a permanent magnet brake according to an embodiment of the present invention;

[0039] Figure 3 A schematic diagram comparing the release state and the braking state of the permanent magnet brake according to an embodiment of the present invention;

[0040] Figure 4 is a flow chart of a control method of a permanent magnet brake according to an embodiment of the present invention;

[0041] Figure 5 is a current variation characteristic diagram of the excitation winding of the permanent magnet brake according to an embodiment of the present invention under a given release voltage;

[0042] Figure 6 The induced voltage variation characteristic diagram of the excitation winding of the permanent magnet brake according to the embodiment of the present invention when a given release voltage is converted to a braking voltage;

[0043] Figure 7 This is a characteristic diagram of the induced voltage and current changes of the excitation winding of the permanent magnet brake of an embodiment of the present invention when the release voltage and the braking voltage are applied alternately and the braking is not performed.

[0044] Description of reference numerals:

[0045] 1-brake unit; 2-control unit; 3-rotational motion unit; 4-transmission unit; 5-transmission shaft;

[0046] 110-fixed component; 111-excitation winding; 112-permanent magnet; 113-fixed member; 114-rolling member;

[0047] 120-rotating assembly; 121-elastic member; 122-releasing member; 123-magnetic member; 124-sleeve;

[0048] 201 - voltage supply module; 202 - current acquisition module; 203 - voltage acquisition module. DETAILED DESCRIPTION

[0049] In order to make the purpose, features and beneficial effects of the present invention more obvious and understandable, the specific embodiments of the present invention are described in detail below in conjunction with the accompanying drawings. It is understood that the specific embodiments described below are only used to explain the present invention, rather than to limit the present invention. In addition, the same or similar reference numerals may be used in the figures to refer to the same or similar elements in different embodiments, and the description of the same or similar elements in different embodiments and the description of the prior art elements, features, effects, etc. may be omitted.

[0050] Reference Figure 1-Figure 3 , an embodiment of the present invention provides a permanent magnet brake.

[0051] Specifically, the permanent magnet brake provided in an embodiment of the present invention includes a braking unit 1 and a control unit 2, the braking unit 1 is arranged on a transmission shaft 5, and the control unit 2 is connected to and controls the braking unit 1; the transmission shaft 5 connects the rotational motion unit 3 and the transmission unit 4, and the rotational motion unit 3 is a rotational drive motor.

[0052] The brake unit 1 includes a rotating component 120 and a fixed component 110 coaxially sleeved on the transmission shaft 5. The rotating component 120 rotates with the transmission shaft 5, and the fixed component 110 is fixedly connected to the vehicle body; the rotating component 120 includes a sleeve 124, a release member 122 and a magnetic member 123. The sleeve 124 is fixedly sleeved on the transmission shaft 5, the release member 122 and the magnetic member 123 are arranged side by side outside the sleeve 124, the release member 122 is fixedly connected to the sleeve 124, and the magnetic member 123 is movably connected to the sleeve 124. The sleeve 124 allows the magnetic member 123 to move axially along the sleeve 124 and prevents the magnetic member 123 from rotating relative to the sleeve 124. An elastic member 121 is arranged between the magnetic member 123 and the release member 122; the fixed component 110 is sleeved outside the sleeve 124 and is located at one end close to the magnetic member 123 A rolling member 114 is arranged between the fixed component 110 and the sleeve 124, and the rolling member 114 allows the transmission shaft 5 to drive the sleeve 124 to rotate relative to the fixed component 110; the fixed component 110 includes a fixed component 113, an excitation winding 111 and a permanent magnet 112, the excitation winding 111 and the permanent magnet 112 are installed on the fixed component 113, and the excitation winding 111 can be arranged on the permanent magnet 112 or arranged side by side with the permanent magnet 112; the control unit 2 is connected to the excitation winding 111, and the control unit 2 includes a voltage supply module 201, a current acquisition module 202 and a voltage acquisition module 203; the voltage supply module 201 outputs voltage to the excitation winding 111, the current acquisition module 202 collects the current of the excitation winding 111, and the voltage acquisition module 203 collects the induced voltage of the excitation winding 111.

[0053] In some embodiments, the magnetic field generated by the excitation winding 111 after being energized is opposite to the direction of the magnetic field of the permanent magnet 112; when the voltage output to the excitation winding 111 is less than the first set voltage, the magnetic field of the excitation winding 111 is much smaller than the magnetic field of the permanent magnet 112, and the total magnetic field of the excitation winding 111 and the permanent magnet 112 has a suction force on the magnetic conductive member 123 that is greater than the elastic force of the elastic member 121, and the magnetic conductive member 123 moves toward the fixed component 110 until it is combined with the fixed component 110, thereby preventing the rotating component 120 and the transmission shaft 5 from rotating, thereby achieving braking; when the voltage output to the excitation winding 111 is greater than the second set voltage and less than the third set voltage, the magnetic field of the excitation winding 111 and the magnetic field of the permanent magnet 112 counteract each other. The suction force of the total magnetic field of the excitation winding 111 and the permanent magnet 112 on the magnetic conductive part 123 is smaller than the elastic force of the elastic part 121, and the magnetic conductive part 123 moves toward the release part 122 until it is separated from the fixed component 110, allowing the rotating component 120 and the transmission shaft 5 to rotate, thereby realizing the brake release; when the voltage output to the excitation winding 111 is greater than the fourth set voltage, the magnetic field of the excitation winding 111 is much greater than the magnetic field of the permanent magnet 112, and the suction force of the total magnetic field of the excitation winding 111 and the permanent magnet 112 on the magnetic conductive part 123 is greater than the elastic force of the elastic part 121, and the magnetic conductive part 123 moves toward the fixed component 110 until it is combined with the fixed component 110, thereby preventing the rotating component 120 and the transmission shaft 5 from rotating, thereby realizing braking.

[0054] In some embodiments, the first setting voltage, the second setting voltage, the third setting voltage and the fourth setting voltage increase sequentially.

[0055] In some embodiments, the release member 122 is made of non-magnetic material, the magnetic conductive member 123 is made of ferromagnetic material, the elastic member 121 is a leaf spring, and the rolling member 114 is a ball or a roller.

[0056] See also Figure 4 The control method of the permanent magnet brake provided by the embodiment of the present invention comprises the following steps:

[0057] S1: Control unit 2 receives the instruction and determines the instruction type;

[0058] S2: If it is a release command, the voltage supply module 201 applies a release voltage U to the excitation winding 111 1 ;

[0059] Release voltage U 1 is greater than the second set voltage and less than the third set voltage, the magnetic field of the excitation winding 111 and the magnetic field of the permanent magnet 112 cancel each other out, the total magnetic field of the excitation winding 111 and the permanent magnet 112 has a suction force on the magnetic conductive member 123 that is less than the elastic force of the elastic member 121, and the magnetic conductive member 123 moves toward the release member 122 until it is separated from the fixed component 110, allowing the rotating component 120 and the transmission shaft 5 to rotate, thereby completing the brake release;

[0060] The excitation winding 111 releases the voltage U 1 The current change characteristics under Figure 5 As shown, at time t 1 Before, the magnetic conductive member 123 and the fixing assembly 110 are still in a combined state, the equivalent inductance is small, and the slope of the current rise is the highest; at time t 1 -t 2 In the stage, the magnetic conductive member 123 is in motion, the equivalent inductance increases, and the current rising slope decreases significantly; at t 2 At time t, the magnetic conductive member 123 stops moving, the equivalent inductance increases to the maximum state, and the current rising slope further decreases significantly; at time t 3 At this time, the slope of the current is very small and reaches a stable stage.

[0061] The current acquisition module 202 collects the real-time current of the excitation winding 111 and calculates the current change slope;

[0062] Determine whether the current change slope has a sudden change. If a sudden change occurs (at t 1 moment), it means that when the current change slope suddenly changes, the magnetic conductive member 123 starts to move toward the release member 122;

[0063] After the current change slope suddenly changes, the current change slope is compared with the set first change slope. If the current change slope is less than or equal to the set first change slope (at t 2 moment), it is determined that the magnetic conductive member 123 is separated from the fixed component 110, and the permanent magnetic brake is released;

[0064] When the current change slope is less than or equal to the set first change slope, it is determined that the permanent magnet brake is released. In the prior art, when the current is stable, that is, t 3 At that moment, it is determined that the brake has been released, which is significantly delayed in time.

[0065] S3: If it is a braking command, the voltage supply module 201 applies a braking voltage U to the excitation winding 111 2 ;

[0066] Braking voltage U 2 Less than the first set voltage, the magnetic field of the excitation winding 111 is much smaller than the magnetic field of the permanent magnet 112, the total magnetic field of the excitation winding 111 and the permanent magnet 112 exerts a suction force on the magnetic conductive part 123 that is greater than the elastic force of the elastic part 121, and the magnetic conductive part 123 moves toward the fixed component 110 until it is combined with the fixed component 110, thereby preventing the rotating component 120 and the transmission shaft 5 from rotating, thereby completing the braking.

[0067] The excitation winding 111 is released by the voltage U 1 Switching to braking voltage U 2 The induced voltage variation characteristics under Figure 6 As shown, at time t 4 Previously, the magnetic conductive member 123 and the fixed component 110 were still in a combined state, the equivalent inductance was the largest, the back electromotive force of the excitation winding 111 decreased, and the slope of change was the highest; at time t 4 -t 5 In the stage, the magnetic conductive member 123 is in motion, the equivalent inductance decreases, the back electromotive force of the excitation winding 111 decreases, and the change slope decreases significantly; at t 5 At time t, the magnetic conductive member 123 stops moving, the equivalent inductance decreases to a minimum state, the back electromotive force of the excitation winding 111 decreases, and the slope of change further decreases significantly; at time t 6 At this time, the slope of the current is very small and reaches a stable stage.

[0068] The voltage acquisition module 203 collects the real-time induced voltage of the excitation winding 111 and calculates the slope of the induced voltage change;

[0069] Determine whether the slope of the induced voltage change has a sudden change. If a sudden change occurs (at t 4 moment), it means that when the slope of the induced voltage change suddenly changes, the magnetic conductive member 123 starts to move toward the fixed component 110;

[0070] After the induced voltage change slope suddenly changes, the induced voltage change slope is compared with the set second change slope. If the induced voltage change slope is less than or equal to the set second change slope (at t 5 moment), it is determined that the magnetic conductive member 123 is combined with the fixed component 110, and the permanent magnet brake completes the braking;

[0071] When the induced voltage change slope is less than or equal to the set second change slope, it is determined that the permanent magnet brake completes braking; the prior art usually determines that the permanent magnet brake completes braking when the voltage is stable, that is, t 6 At this moment, it is determined that the brake has completed braking, which is obviously delayed in time.

[0072] More precise structural state control saves unnecessary waiting time and reduces energy consumption in the waiting link of the control system; saves unnecessary circuit signal steady-state waiting time and achieves faster release and combination; can identify the position state of the magnetic component 123, and control is more accurate and reliable, and the braking process is safer; there is no need for excessively high product quality consistency and product process performance consistency, which reduces the requirements for materials and design and has obvious cost advantages.

[0073] In some embodiments, the control unit 2 receives a release instruction and needs to maintain a certain release time, and in the release state, the release voltage U is applied to the excitation winding 111 in turn. 1 and braking voltage U 2 When the brake is kept on, the induced voltage and current variation characteristics of the excitation winding 111 are as follows: Figure 7As shown, the specific control method is as follows:

[0074] The voltage supply module 201 applies a release voltage U to the excitation winding 111. 1 ;

[0075] The current acquisition module 202 collects the real-time current of the excitation winding 111 and calculates the current change slope;

[0076] When the current change slope is less than or equal to a set first change slope, determining that the permanent magnet brake has completed release;

[0077] The voltage supply module 201 applies a braking voltage U to the excitation winding 111. 2 ;

[0078] The voltage acquisition module 203 collects the real-time induced voltage of the excitation winding 111 and calculates the slope of the induced voltage change;

[0079] Determine whether the slope of the induced voltage change has a sudden change (at t 7 At this moment), if a sudden change occurs and the induced voltage change slope is less than or equal to the set third change slope (at t 8 When the third change slope is slightly greater than the second change slope, it indicates that the magnetic conductive member 123 is in a critical combination state with the fixing assembly 110;

[0080] The voltage supply module 201 applies a release voltage U to the excitation winding 111 again. 1 ;

[0081] The current acquisition module 202 collects the real-time current of the excitation winding 111 and calculates the current change slope;

[0082] When the current change slope is less than or equal to the set first change slope (at t 9 At the time (time), it is determined that the permanent magnet brake is released;

[0083] The voltage supply module 201 applies a release voltage U to the excitation winding 111 in turn. 1 and braking voltage U 2 , so that the magnetic member 123 switches between the release state and the critical combination state until the control unit 2 receives a braking command. Keeping the brake on and switching the magnetic member 123 between the release state and the critical combination state is better than always applying the release voltage U 1 To keep the released state more energy-efficient.

[0084] In summary, the permanent magnet brake and the control method thereof provided by the present invention realize the control of the magnetic conductive part 123 through the total magnetic field of the permanent magnet 112 and the excitation winding 111, thereby realizing the braking and releasing of the permanent magnet brake. The magnetic fields of the permanent magnet 112 and the excitation winding 111 are in opposite directions, so that the excitation winding 111 can be powered off and released. The permanent magnet brake is affected by the movement of the structural components of the permanent magnet brake during the release and braking process. The state of the permanent magnet brake is confirmed by the change of the voltage and current slope of the excitation winding 111, thereby avoiding the influence of differences in circuit control parameters caused by factors such as product production performance deviation, environmental impact, and aging during use, thereby improving safety, reliability and response performance.

[0085] Furthermore, the permanent magnet brake and control method thereof provided by the present invention applies a release voltage U to the excitation winding 111 in turn after power-on release. 1 and braking voltage U 2 , so that the magnetic conductive member 123 switches between the release state and the critical combination state, compared with always applying the release voltage U 1 To keep the released state more energy-efficient.

[0086] Although specific embodiments have been described above, these embodiments are not intended to limit the scope of the present disclosure, even when only a single embodiment is described with respect to specific features. The feature examples provided in the present disclosure are intended to be illustrative rather than limiting, unless otherwise stated. In specific implementations, the technical features of one or more dependent claims may be combined with the technical features of the independent claim, based on actual needs and where technically feasible, and may be derived from the technical features of the corresponding independent claim in any appropriate manner rather than simply through the specific combination listed in the claims.

[0087] Although the present invention is disclosed as above, the present invention is not limited thereto. Any person skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the scope defined by the claims.

Claims

1. A control method for a permanent magnet brake, the permanent magnet brake comprising a brake unit and a control unit, the brake unit comprising a rotating assembly and a fixed assembly coaxially sleeved on a transmission shaft, the rotating assembly rotates with the transmission shaft; the fixed assembly is fixedly connected to a vehicle body and is located on one side of the rotating assembly, the fixed assembly comprises a fixing part, an excitation winding and a permanent magnet, the excitation winding and the permanent magnet are mounted on the fixing part; the control unit comprises a voltage supply module, a current acquisition module and a voltage acquisition module, which are respectively used to output voltage to the excitation winding, collect the current of the excitation winding and collect the induced voltage of the excitation winding; it is characterized in that, The steps include: The control unit receives the instruction and determines the instruction type; If it is a release instruction, the voltage supply module applies a release voltage U1 to the excitation winding; when the release voltage U1 is greater than the second set voltage and less than the third set voltage, the permanent magnet brake realizes brake release; The current acquisition module collects the real-time current of the excitation winding and calculates the current change slope; When the current change slope is less than or equal to a set first change slope, determining that the permanent magnet brake has completed release; If it is a braking instruction, the voltage supply module applies a braking voltage U2 to the excitation winding; when the braking voltage U2 is less than the first set voltage, the permanent magnet brake realizes braking; the first set voltage, the second set voltage and the third set voltage increase in sequence; The voltage acquisition module collects the real-time induced voltage of the excitation winding and calculates the slope of the induced voltage change; When the induced voltage change slope is less than or equal to a set second change slope, it is determined that the permanent magnet brake completes braking.

2. The control method of the permanent magnet brake according to claim 1, characterized in that: The release voltage U1 is greater than the second set voltage and less than the third set voltage, the magnetic field of the excitation winding and the magnetic field of the permanent magnet cancel each other out, the total magnetic field of the excitation winding and the permanent magnet has a suction force on the magnetic conductive part that is less than the elastic force of the elastic part, and the magnetic conductive part moves toward the release part until it is separated from the fixed component, allowing the rotating component and the transmission shaft to rotate, thereby completing the brake release.

3. The control method of the permanent magnet brake according to claim 2, characterized in that: After calculating the current change slope, it also includes: Determine whether the current change slope suddenly changes. If so, it means that the magnetic conductive member starts to move toward the release member when the current change slope suddenly changes. After the current change slope suddenly changes, the current change slope is compared with the set first change slope. If the current change slope is less than or equal to the set first change slope, it is determined that the magnetic conductive part is separated from the fixed component and the permanent magnet brake is released.

4. The control method of the permanent magnet brake according to claim 1, characterized in that: The braking voltage U2 is lower than the first set voltage, the magnetic field of the excitation winding is much lower than the magnetic field of the permanent magnet, the total magnetic field of the excitation winding and the permanent magnet has a suction force on the magnetic conductive part that is greater than the elastic force of the elastic part, and the magnetic conductive part moves toward the fixed component until it is combined with the fixed component, thereby preventing the rotating component and the transmission shaft from rotating and completing the braking.

5. The control method of the permanent magnet brake according to claim 4, characterized in that: After calculating the slope of the induced voltage change, it also includes: Determine whether the slope of the induced voltage change suddenly changes. If so, it means that the magnetic conductive component starts to move toward the fixed component when the slope of the induced voltage change suddenly changes. After the induced voltage change slope changes suddenly, the induced voltage change slope is compared with the set second change slope. If the induced voltage change slope is less than or equal to the set second change slope, it is determined that the magnetic conductive part is combined with the fixed component and the permanent magnet brake completes braking.

6. The control method of the permanent magnet brake according to claim 1, characterized in that: The following steps are also included: The control unit receives a release instruction; The voltage supply module applies a release voltage U1 to the excitation winding; The current acquisition module collects the real-time current of the excitation winding and calculates the current change slope; When the current change slope is less than or equal to a set first change slope, determining that the permanent magnet brake has completed release; The voltage supply module applies a braking voltage U2 to the field winding; The voltage acquisition module collects the real-time induced voltage of the excitation winding and calculates the voltage change slope; Determine whether the induced voltage change slope has a sudden change. If a sudden change occurs and the induced voltage change slope is less than or equal to the set third change slope, it indicates that the magnetic conductive component is in a critical combination state with the fixed component; The voltage supply module applies a release voltage U1 and a brake voltage U2 to the excitation winding in turn, so that the magnetic conductive member switches between a release state and a critically coupled state until the control unit receives a brake command.

7. A control unit, characterized in that: Used to implement a control method for a permanent magnet brake as described in any one of claims 1-6.

8. A permanent magnet brake, characterized in that: Comprising a control unit as claimed in claim 7.

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