WO2020135750A1 - 打草机以及打草机的控制方法 - Google Patents

打草机以及打草机的控制方法 Download PDF

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Publication number
WO2020135750A1
WO2020135750A1 PCT/CN2019/129294 CN2019129294W WO2020135750A1 WO 2020135750 A1 WO2020135750 A1 WO 2020135750A1 CN 2019129294 W CN2019129294 W CN 2019129294W WO 2020135750 A1 WO2020135750 A1 WO 2020135750A1
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WO
WIPO (PCT)
Prior art keywords
spool
head
vector
brushless motor
voltage vector
Prior art date
Application number
PCT/CN2019/129294
Other languages
English (en)
French (fr)
Inventor
代修波
Original Assignee
南京德朔实业有限公司
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by 南京德朔实业有限公司 filed Critical 南京德朔实业有限公司
Priority to EP19905837.1A priority Critical patent/EP3884757B1/en
Priority to CN201980062900.XA priority patent/CN112752501B/zh
Publication of WO2020135750A1 publication Critical patent/WO2020135750A1/zh
Priority to US17/357,568 priority patent/US11439059B2/en

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Classifications

    • A—HUMAN NECESSITIES
    • A01—AGRICULTURE; FORESTRY; ANIMAL HUSBANDRY; HUNTING; TRAPPING; FISHING
    • A01G—HORTICULTURE; CULTIVATION OF VEGETABLES, FLOWERS, RICE, FRUIT, VINES, HOPS OR SEAWEED; FORESTRY; WATERING
    • A01G3/00—Cutting implements specially adapted for horticultural purposes; Delimbing standing trees
    • A01G3/06—Hand-held edge trimmers or shears for lawns
    • A01G3/067—Motor-driven shears for lawns
    • A—HUMAN NECESSITIES
    • A01—AGRICULTURE; FORESTRY; ANIMAL HUSBANDRY; HUNTING; TRAPPING; FISHING
    • A01D—HARVESTING; MOWING
    • A01D34/00—Mowers; Mowing apparatus of harvesters
    • A01D34/01—Mowers; Mowing apparatus of harvesters characterised by features relating to the type of cutting apparatus
    • A01D34/412—Mowers; Mowing apparatus of harvesters characterised by features relating to the type of cutting apparatus having rotating cutters
    • A01D34/416—Flexible line cutters
    • A01D34/4161—Means for feeding cutter line
    • A01D34/4162—Means for feeding cutter line automatically
    • A—HUMAN NECESSITIES
    • A01—AGRICULTURE; FORESTRY; ANIMAL HUSBANDRY; HUNTING; TRAPPING; FISHING
    • A01D—HARVESTING; MOWING
    • A01D34/00—Mowers; Mowing apparatus of harvesters
    • A01D34/01—Mowers; Mowing apparatus of harvesters characterised by features relating to the type of cutting apparatus
    • A01D34/412—Mowers; Mowing apparatus of harvesters characterised by features relating to the type of cutting apparatus having rotating cutters
    • A01D34/416—Flexible line cutters
    • A01D34/4161—Means for feeding cutter line
    • A01D34/4163—Means for feeding cutter line by triggered line feedout, e.g. bump-feeding
    • A—HUMAN NECESSITIES
    • A01—AGRICULTURE; FORESTRY; ANIMAL HUSBANDRY; HUNTING; TRAPPING; FISHING
    • A01D—HARVESTING; MOWING
    • A01D34/00—Mowers; Mowing apparatus of harvesters
    • A01D34/01—Mowers; Mowing apparatus of harvesters characterised by features relating to the type of cutting apparatus
    • A01D34/412—Mowers; Mowing apparatus of harvesters characterised by features relating to the type of cutting apparatus having rotating cutters
    • A01D34/416—Flexible line cutters
    • A01D34/4166—Mounting or replacement of the lines
    • A—HUMAN NECESSITIES
    • A01—AGRICULTURE; FORESTRY; ANIMAL HUSBANDRY; HUNTING; TRAPPING; FISHING
    • A01D—HARVESTING; MOWING
    • A01D34/00—Mowers; Mowing apparatus of harvesters
    • A01D34/01—Mowers; Mowing apparatus of harvesters characterised by features relating to the type of cutting apparatus
    • A01D34/412—Mowers; Mowing apparatus of harvesters characterised by features relating to the type of cutting apparatus having rotating cutters
    • A01D34/63—Mowers; Mowing apparatus of harvesters characterised by features relating to the type of cutting apparatus having rotating cutters having cutters rotating about a vertical axis
    • A01D34/76—Driving mechanisms for the cutters
    • A01D34/78—Driving mechanisms for the cutters electric
    • A—HUMAN NECESSITIES
    • A01—AGRICULTURE; FORESTRY; ANIMAL HUSBANDRY; HUNTING; TRAPPING; FISHING
    • A01G—HORTICULTURE; CULTIVATION OF VEGETABLES, FLOWERS, RICE, FRUIT, VINES, HOPS OR SEAWEED; FORESTRY; WATERING
    • A01G3/00—Cutting implements specially adapted for horticultural purposes; Delimbing standing trees
    • A01G3/06—Hand-held edge trimmers or shears for lawns
    • A01G3/062—Motor-driven edge trimmers

Definitions

  • the present application relates to a garden tool, for example, to a lawnmower and a control method of the lawnmower.
  • a lawnmower is a garden tool used to trim lawns.
  • the grass cutter includes a grass cutter head, and the grass cutter head rotates at a high speed to drive the grass cutter rope installed thereon to realize the cutting function.
  • the grassing head includes a spool for winding the grassing rope.
  • the grassing rope is gradually consumed due to wear.
  • the user needs to replace the new grass rope and wind the grass rope onto the spool.
  • the lawn mower with automatic winding mode came into being.
  • the grass cutter with automatic winding mode can automatically wind the grass rope to the spool.
  • the present application provides a lawn mower having an automatic winding mode and a stable winding speed and a control method of the lawn mower.
  • a lawn mower includes: a grass head; a brushless motor for driving the grass head to rotate to cut vegetation; a drive circuit connected to the motor to drive the motor to output power; a controller, and The driving circuit is connected to control the driving circuit;
  • the grassing head includes a spool and a head shell, the spool is used to wind a grassing rope, and the head shell is used to accommodate the spool;
  • the grassing The machine has an automatic winding mode in which the brushless motor drives at least one of the spool and the head housing to relatively rotate the spool and the head housing to move the The grass rope is automatically wound to the spool;
  • the controller is configured to: in the automatic winding mode, output a control signal to the drive circuit according to at least one of a given voltage and a given current
  • the speed of the brushless motor is basically constant.
  • the spool and the head case are subjected to varying resistance; at least one of the given voltage and the given current enables the controller output to cause the spool and the At least one of the head shells overcomes the control signal of the resistance with the largest resistance value among the changed resistances.
  • the changing resistance fluctuates periodically.
  • the controller includes: a PWM signal determination module for calculating and determining the resistance output by the controller that can cause at least one of the spool and the head case to overcome the changed resistance according to the given voltage The PWM signal of the resistance with the largest value; a PWM signal generation module, configured to generate a PWM signal according to the PWM signal determined by the PWM signal determination module to control the drive circuit.
  • the PWM signal determination module includes: a voltage vector given unit for giving a target voltage vector, the amplitude of the target voltage vector is equal to the amplitude of the given voltage; the vector action time unit is used for The target voltage vector given by the voltage vector given unit determines the action time of the basic voltage vector and the zero vector combined into the target voltage vector, the input end of the vector action time unit and the voltage vector given unit The output terminal is connected; the vector switching point unit is used to determine the switching time point of the basic voltage vector and the zero vector, and the input terminal of the vector switching point unit is connected to the output terminal of the vector acting time unit.
  • the controller is configured to: in the automatic winding mode, output a control signal to the driving circuit according to at least one of the given voltage and the given current to generate a rotating magnetic field in the brushless motor , At least one of the bobbin and the head shell rotates substantially synchronously with the rotating magnetic field.
  • At least one of the head housing and the bobbin rotates about a central axis, the central axis substantially coincides with the axis of the drive shaft, and the drive shaft is driven by the brushless motor to drive the grass head;
  • the spool is formed with a first inclined surface
  • the head case is formed with a second inclined surface, the first inclined surface and the second inclined surface are inclined to the normal plane of the central axis; in the automatic winding mode, the first A slanted surface and the second slanted surface are in contact with each other and slide relative to each other to enable the spool and the head housing to rotate relatively.
  • the spool is formed with a plurality of first meshing teeth arranged circumferentially around the central axis, the first meshing teeth are formed with the first inclined surface; the head housing is formed with the plurality of first meshing teeth A plurality of first mating teeth with tooth engagement, the first mating teeth being formed with the second slope.
  • Two adjacent first meshing teeth of the plurality of first meshing teeth are spaced apart from each other by a second size in the circumferential direction of the central axis.
  • the lawnmower also has a cutting mode; in the cutting mode, the first meshing teeth and the first mating teeth stop each other; in the automatic winding mode, the first meshing teeth and The first mating teeth contact each other and slide relatively.
  • the first inclined surface formed by each of the first meshing teeth of the plurality of first meshing teeth is inclined along the circumferential direction of the central axis; each first meshing tooth of the plurality of first meshing teeth
  • the second inclined surface formed is inclined along the circumferential direction of the central axis.
  • the lawnmower also has a cutting mode in which the spool and the head shell rotate synchronously; the controller is configured to: in the cutting mode, control the The drive circuit causes the brushless motor to operate at a first speed; in the automatic winding mode, the drive circuit is controlled to operate the brushless motor at a second speed in a second control mode; the second The rotation speed is less than the first rotation speed.
  • the value range of the ratio of the first rotation speed to the second rotation speed is 10-100.
  • the controller is configured to: in the cutting mode, make the brushless motor rotate in the first direction at the first speed; in the automatic winding mode, make the brushless motor use The second rotation speed rotates in a second direction; the first direction is opposite to the second direction.
  • the lawn mower is powered by a power supply, and the ratio of the given voltage to the voltage of the power supply ranges from 0.1 to 0.5.
  • a control method for a grass mower the grass mower has an automatic winding mode, the grass mower includes a grass head, a brushless motor that drives the grass head, and a drive that drives the operation of the brushless motor A circuit, a controller that controls the driving circuit; a control method of the lawn mower includes: in the automatic winding mode, outputting a control signal to the driving circuit according to at least one of a given voltage and a given current The rotation speed of the brushless motor is substantially constant.
  • the grassing head includes a spool and a head shell, the spool is used to wind a grass rope, and the head shell is used to accommodate the spool; in the automatic winding mode, the spool and the head shell are subjected to Varying resistance; at least one of the given voltage and the given current enables at least one of the spool and the head housing to overcome the resistance with the largest resistance value of the varying resistance.
  • the control method of the lawn mower includes: given a target voltage vector, the amplitude of the target voltage vector is equal to the amplitude of the given voltage; determining a basic voltage vector and a zero vector that synthesize the target voltage vector; Determine the action time of the basic voltage vector and the zero vector; determine the switching time point of the basic voltage vector and the zero vector; according to the basic voltage vector, the zero vector and the basic voltage vector and the zero vector The switching time determines the PWM signal.
  • At least one of the head housing and the bobbin rotates about a central axis, the central axis substantially coincides with the axis of the drive shaft, and the drive shaft is driven by the brushless motor to drive the grass head;
  • the spool is formed with a first inclined surface
  • the head case is formed with a second inclined surface, the first inclined surface and the second inclined surface are inclined to the normal plane of the central axis; in the automatic winding mode, the first A slanted surface and the second slanted surface are in contact with each other and slide relative to each other to enable the spool and the head housing to rotate relatively.
  • the lawnmower also has a cutting mode in which the spool and the head shell rotate synchronously; the controller is configured to: in the cutting mode, control the The drive circuit causes the brushless motor to rotate in the first direction at a first speed; in the automatic winding mode, the drive circuit is controlled in a second control mode so that the brushless motor rotates along the second speed at a second speed Run in two directions; the second speed is less than the first speed, and the second direction is opposite to the first direction.
  • the lawn mower and the control method of the lawn mower of the present application can achieve the control effect of stable low speed and high torque of the motor when the lawn mower is in the automatic winding mode, and the motor speed is basically kept constant by the influence of load fluctuations.
  • the winding speed is more stable and the user experience is better.
  • FIG. 1 is a schematic diagram of a lawn mower as an embodiment
  • FIG. 2 is a partial structural schematic diagram of FIG. 1;
  • Figure 3 is a cross-sectional view of the structure in Figure 2;
  • Figure 4 is an exploded view of the structure in Figure 2;
  • FIG. 5 is an exploded view of the structure in FIG. 2 from another perspective
  • FIG. 6 is a schematic diagram of the upper cover of the head shell in FIG. 5;
  • FIG. 7 is a schematic diagram of the bobbin in FIG. 5;
  • FIG. 8 is a schematic diagram of the operating device in FIG. 1;
  • FIG. 9 is a circuit block diagram of an embodiment of the lawn mower.
  • FIG. 10 is a schematic diagram of the driving circuit in FIG. 9;
  • FIG. 9 is an internal block diagram of the controller in FIG. 9;
  • Figure 12 is a vector diagram of voltage space
  • Fig. 13 is a flowchart of a control method of a lawn mower according to an embodiment.
  • the lawn mower 100 includes a grass head 110, a driving device 120 and an operating device 130.
  • the grassing head 110 is used to install and store the grassing rope 101, and a part of the grassing rope 101 is stored inside the grassing head 110, and a part of the grassing head 101 extends out of the grassing head 110 for use in the grassing head 110 Cut vegetation while rotating.
  • the operation device 130 is used for user operation to control the lawn mower 100.
  • the driving device 120 can drive the grassing head 110 to rotate around a central axis 110a, thereby driving the grassing rope 101 to rotate to cut vegetation.
  • the drive device 120 includes a motor 121 and a drive shaft 122.
  • the driving shaft 122 is connected to the rotor 121a of the motor 121, and is driven by the rotor 121a of the motor 121.
  • the motor 121 is used to drive the grass head 110 to rotate to cut vegetation.
  • the driving shaft 122 is connected to the grass head 110 in a rotation-proof manner to drive the grass head 110 to rotate.
  • the motor 121 is a brushless motor 901 (FIG. 9), and the motor 121 further includes a rotor 121a.
  • the drive shaft 122 is the motor shaft of the motor 121, the central axis 110a is the axis of the motor shaft, and the drive shaft 122 is mechanically connected to the motor shaft of the motor 121.
  • the lawnmower 100 further includes a first casing 150 and a second casing 160.
  • the role of the first housing 150 is to install and house the motor 121.
  • the lawn mower 100 is powered by a power source, which may be a DC power source or an AC power source.
  • the power supply is a battery pack 170, which serves as an energy source for at least the motor 121 in the lawn mower 100, and the second housing 160 is used to detachably fit the battery pack 170.
  • a circuit board is also accommodated in the second housing 160, and the circuit board is electrically connected to the motor 121 so that the battery pack 170 supplies power to the motor 121 and controls the motor 121.
  • the link assembly 190 connects the first housing 150 and the second housing 160.
  • the operation device 130 is fixed to the link assembly 190.
  • the lawnmower 100 also includes an auxiliary handle 191 for the user to hold, the auxiliary handle 191 is fixed to the link assembly 190.
  • the grass cutting rope 101 is attached to the grass cutting head 110.
  • the shield 180 is used to realize the function of safety protection and prevent the grass rope 401 from causing harm to the user.
  • the grass head 110 includes a spool 111 and a head shell 112.
  • the spool 111 is used for winding the mowing rope 101 and connected to the driving shaft 122 so as to be driven to rotate around the central axis 110a by the driving shaft 122.
  • the head case 112 includes an upper cover 112a and a lower cover 112b.
  • the grass head 110 further includes a fan 112c.
  • the fan 112c is formed with blades for generating airflow.
  • the motor 121 can drive the fan 112c to rotate to generate airflow.
  • a one-way bearing 140 is also provided as a damping device.
  • the function of the one-way bearing 140 is to make the head housing 112 and the motor 121 form a one-way rotational connection.
  • a support member 152 is also provided. The support member 152 is connected to the motor 121 and allows the drive shaft 122 to pass therethrough. It is formed with a boss portion 152a (FIG. 5) to support the inner ring of the one-way bearing 140.
  • the one-way bearing 140 is not directly connected to the head housing 112 but is disposed between the support member 152 and the fan 112c, so that the fan 112c can only rotate in one direction relative to the support member 152, and because the fan 112c and the head housing 112 form a stop Revolving connection, so the head shell 112 can only rotate in one direction relative to the support 152.
  • the upper cover 112a is formed with first connection teeth 112d
  • the fan 112c is formed with second connection teeth 112e that are coupled with the first connection teeth 112d.
  • the first connection teeth 112d and the second connection teeth 112e cooperate to realize the synchronous rotation of the upper cover 112a and the fan 112c .
  • the guiding effect of the cooperation between the first connecting teeth 112d and the second connecting teeth 112e enables the head housing 112 to slide along the central axis 110a relative to the fan 112c, and enables the fan 112c to rotate with the head housing 112 about the central axis 110a, that is, the fan 112c It forms a rotation-proof connection with the head shell 112.
  • the lawnmower 100 also includes a protective cover 151.
  • the protective cover 151 is fixed to the first housing 150.
  • the protective cover 151 covers the blades of the fan 112c at least in the radial direction of the central axis 110a to prevent grass cuttings from winding around the fan 112c.
  • the protective cover 151 changes the flow direction of the air flow of the fan 112c, so that the air flow generated by the fan 112c can blow out grass debris outward in the radial direction of the central axis 110a.
  • the driving shaft 122 directly drives the spool 111 to rotate.
  • the head housing 112 can rotate relative to the spool 111 or slide relative to the spool 111 in the axial direction (ie, the direction of the central axis 110a).
  • At least one of the head housing 112 and the spool 111 rotates about the central axis 110a.
  • the central axis 110a substantially coincides with the axis of the drive shaft 122.
  • the drive shaft 122 is driven by the brushless motor 901 to drive the grass head 110.
  • the spool 111 is formed with a first inclined surface 111h
  • the head shell 112 is formed with a second inclined surface 112j.
  • the first inclined surface 111h and the second inclined surface 112j are inclined to the normal plane of the central axis 110a, and the normal plane of the central axis 110a is perpendicular to the The central axis 110a is described.
  • the first inclined surface 111h and the second inclined surface 112j are in contact with each other and relatively slide so that the spool 111 and the head housing 112 can relatively rotate.
  • the spool 111 is formed with a plurality of first meshing teeth 111a arranged circumferentially around the central axis 110a; the head housing 112 is formed with a plurality of first meshing teeth 111a that cooperate with the plurality of first meshing teeth 111a Mating teeth 112f; the first meshing teeth 111a are formed with a first inclined surface 111h, the first engaging teeth 112f are formed with a second inclined surface 112j, the first inclined surface 111h and the second inclined surface 112j are inclined to the normal plane of the central axis 110a, In the automatic winding mode, the first inclined surface 111h and the second inclined surface 112j are in contact with each other and relatively slide so that the spool 111 and the head housing 112 can relatively rotate.
  • Two adjacent first meshing teeth 111a among the plurality of first meshing teeth 111a are spaced apart from each other by a second size in the circumferential direction of the central axis 110a.
  • the first inclined surface 111h formed by each first engaging tooth is inclined along the circumferential direction of the central axis 110a;
  • the second inclined surface 112j formed by each first engaging tooth 112f is inclined along the circumferential direction of the central axis 110a .
  • the first meshing teeth 111a are formed on the upper portion of the bobbin 111, and the first meshing teeth 111a are helical teeth.
  • the first mating teeth 112f are formed in the head case 112, and the first mating teeth 112f are formed in the upper cover 112a.
  • the first meshing teeth 111a and the first mating teeth 112f adopt a slope design, the first meshing teeth 111a and the first mating teeth 112f can only be driven in one direction.
  • the first meshing teeth 112f and The first meshing teeth 111a are in a mutual stop state so that when the bobbin 111 rotates, the head housing 112 can be driven to rotate synchronously, and when the lawnmower 100 is in the automatic winding mode, when the bobbin 111 and the head housing 112 are relatively rotated in opposite directions,
  • the slippage due to the inclined surface enables the first mating teeth 112f and the first meshing teeth 111a to relatively slide, so that the spool 111 and the head housing 112 can continuously rotate relatively. That is to say, in the cutting mode, the first engaging teeth 111a and the first engaging teeth 112f stop each other; in the automatic winding mode, the first engaging teeth 111a and the first engaging teeth 112f are in contact with each
  • the lower part of the spool 111 is formed with second meshing teeth 111b
  • the head housing 112 is formed with second mating teeth 112g
  • the second mating teeth 112g are formed on the lower cover 112b
  • the second meshing teeth 111b and the second mating teeth 112g Beveled.
  • the second meshing teeth 111b and the second mating teeth 112g can form an engagement when the head housing 112 is in the second axial position relative to the bobbin 111, and the transmission surfaces of the second meshing teeth 111b and the second mating teeth 112g adopt a slope design.
  • the drive shaft 122 drives the spool 111 to reverse, and the head housing 112 causes relative movement between the spool 111 and the head housing 112 because the one-way bearing 140 prevents it from reversing.
  • the spool The reason why the contact surface between 111 and the head housing 112 is a slant surface is that the first meshing teeth 111a and the first mating teeth 112f cannot completely prevent the relative movement of the spool 111 and the head housing 112, so the spool 111 and the head housing 112 can be continuous Relative rotation occurs so that the mower can perform the automatic winding mode.
  • the spool 111 and the head housing 112 will be subjected to varying resistance. It is a resistance to periodic fluctuations.
  • the grass head 110 further includes a spring 110b that exerts a force between the lower cover 112b and the spool 111 to bias the head housing 112 to an axial position that rotates synchronously with the spool 111. At this time, the head housing 112 is positioned relative to the spool 111 The first axial position.
  • the grass head 110 further includes a first contact 110c and a second contact 110d.
  • the spring 110b is provided between the first contact 110d and the second contact 110e.
  • the spring 110b may directly act on the first contact 110c and the second contact 110d.
  • the first contact 110c and the second contact 110d can avoid the abrasion of the bobbin 111 and the head housing 112 by the spring 110b.
  • the first contact 110d and the second contact 110e are metal parts.
  • the grass head 110 further includes a knock cap 110e.
  • the knock cap 110e is rotatably connected to the lower cover 112b.
  • a bearing 110f is provided between the knock cap 110e and the lower cover 112b so that the knock cap 110e and the lower cover 112b can be opposed
  • the knocking cap 110e and the lower cover 112b move synchronously in the direction of the axis 110a, that is to say, changing the position of the knocking cap 110e, the lower cover 112b can also move together, that is, the head shell 112 will be knocked
  • the knocking cap 110e changes the axial position.
  • the user taps the grass head 110, and the knock cap 110e contacts the ground to cause the head housing 112 to slide to a position where the first engaging teeth 112f and the first engaging teeth 111a are disengaged, thereby Relatively rotating them, knocking makes the head housing 112 slide to a second axial position relative to the spool 111, so that the head housing 112 rotates with respect to the spool 111 at a relatively low rotational speed, thereby winding the grass on the spool 111
  • the rope 101 releases a portion out of the head shell 112, causing the lawn mower 100 to perform a pay-off mode.
  • This has the advantage that while the motor 121 is still rotating at the rotation speed in the cutting mode, the relative rotation speed of the head shell 112 and the spool 111 is controlled, so that the user can prevent the excessive cutting rope 101 from being released every time the tapping is performed.
  • the knocking cap 110e can rotate freely with respect to the lower cover 112b under the action of the bearing 110f, which reduces the wear of the grass head 110.
  • the spring 110b applies a force to the head housing 112 to move the head housing 112 downward relative to the bobbin 111.
  • a shock absorber 110g for easing the impact between the upper cover 112a and the spool 111 is provided.
  • the shock absorber 110g may be a rubber washer.
  • the bobbin 111 is formed with an inner threading hole 111c for fixing the grass rope 101.
  • the head casing 112 is formed with an outer threading hole 112h that allows the grass string 101 to pass out from the inside of the head casing 112 to the outside of the head casing 112.
  • the outer threading hole 112h and the inner threading hole 111c are automatically aligned in the circumferential direction.
  • the outer threading hole 112h and the inner threading hole 111c are automatically aligned in the circumferential direction.
  • the bobbin 111 is formed with a plurality of inner threading holes 111c (FIG. 3), and the number of the inner threading holes 111c is an even number.
  • the plurality of inner threading holes 111c are evenly distributed in the circumferential direction of the axis 110a of the bobbin 111.
  • the number of first meshing teeth 111a corresponds to the number of inner threading holes 111c.
  • the number of second meshing teeth 111b corresponds to the number of inner threading holes 111c.
  • the bobbin 111 is formed with six inner threading holes 111c.
  • the bobbin 111 is formed with six first meshing teeth 111a and six second meshing teeth 111b. Two adjacent first meshing teeth 111a of the plurality of first meshing teeth 111a are spaced apart from each other by a second size in the circumferential direction of the axis 110a.
  • the bobbin 111 is formed with a guide opening 111 d to guide the grassing rope 101 into the inner threading hole 111 c, and the guide opening 111 d gradually expands in the radial direction of the rotation axis of the bobbin 111.
  • the maximum dimension L1 of the guide opening 111d in the circumferential direction of the axis 110a is larger than the maximum dimension L2 of the two first meshing teeth in the circumferential direction of the axis 110a.
  • the transmission surfaces of the first meshing teeth 111a and the first mating teeth 112f are arranged so that when the motor 121 is stopped, the outer threading hole 112h and the inner threading hole 111c are automatically aligned in the circumferential direction.
  • the alignment here means that the grass string 101 passing through the outer threading hole 112h can be directly guided into the inner threading hole 111c.
  • a first flange 111e and a second flange 111f are formed at both ends of the bobbin 111, respectively.
  • a partition plate 111g is formed in the middle of the bobbin 111.
  • a first winding portion is formed between the first flange 111e and the partition plate 111g for winding and accommodating the grass rope 101; a second winding portion 111f and the partition plate 111g are formed for winding and accommodating the grass rope 101 The second winding part.
  • the driving shaft 122 rotates to rotate the bobbin 111, and the bobbin 111 drives the upper cover 112a to rotate.
  • the fan 112c is driven to rotate by the upper cover 112a.
  • the fan 112c can rotate relative to the second housing 160 in a first direction (refer to the direction indicated by arrow B in FIG. 2).
  • the motor 121 rotates forward to drive the spool 111 and the head housing 112 to rotate in the first direction.
  • the user can pass the two ends of a grass rope 101 through the two outer threading holes 112h of the head shell 112, and then the two ends of the grass rope 101 extend into the spool 111 Two opposite inner threading holes 111c.
  • the user can also insert the two grass ropes 101 into the two inner threading holes 111c, respectively.
  • the user controls the lawn mower 100 to make the lawn mower 100 execute the automatic winding mode, and the motor 121 reversely rotates to drive the bobbin 111 to rotate in the second direction opposite to the first direction.
  • the fan 112c and the head housing 112 cannot rotate in the second reverse direction, and the winding shaft 111 can be rotated relative to the head housing 112 in the second direction by the driving shaft 122 to realize automatic winding.
  • first meshing teeth 111a, the second meshing teeth 111b, the first meshing teeth 111f, the second meshing teeth 110g and the second meshing teeth 110g formed directly on the head housing 112 and the spool 111 are formed with a slope inclined to the normal plane of the central axis 110a.
  • the inclined surfaces of the first meshing teeth 111a and the second meshing teeth 111b are in contact with the inclined surfaces of the first mating teeth 110f and the second mating teeth 110g. Due to the slippage of the inclined surfaces, the inclined surfaces cannot prevent the spool 111 and the head housing 112 from relatively rotating
  • the bobbin 111 can rotate relative to the head housing 112 in the second direction to realize automatic winding.
  • the lawnmower 100 also includes a wire breaking device 181 (see FIG. 1).
  • the thread breaking device 181 automatically cuts the grass cutting rope 101 in the automatic winding mode.
  • the disconnecting device 181 includes a disconnecting element 182, and the grass head 110 can rotate relative to the disconnecting element 182.
  • the breaking element 182 is fixed to the shield 180.
  • the grass cutting rope 101 can be driven by the grass cutting head 110 to pass through the wire cutting element 182, and the grass cutting rope 101 is cut by the wire cutting element 182 after being tensioned.
  • the breaking element 182 can break the grass cutting rope 101, and the middle part of the grass cutting rope 101 is broken to become a two-stage grass cutting rope 101.
  • the striking rope 101 can be directly knocked off when the striking rope 101 is tightly stretched outside the head shell 112.
  • the operating device 130 includes a first operating member 131 and a second operating member 132.
  • the first operating member 131 has an initial state and a first preset operating state.
  • the second operating member 132 has an initial state and a second preset operating state.
  • the operation device 130 includes a first reset component 133 and a second reset component 134.
  • the first reset component 133 disengages the first operating member 131 from the first preset state when the user does not operate the first operating member 131.
  • the second reset component 134 disengages the second operating member 132 from the second preset state when the user does not operate the second operating member 132.
  • the first operating member 131 is operated to move to the first preset In the operating state, the mower 100 is now in the cutting mode.
  • the operation of the lawnmower 100 also depends on the circuit system 900 composed of circuit components.
  • the motor 121 selects the brushless motor 901, and the lawnmower 100 further includes a drive circuit 902 and a controller 903 ⁇ Power circuit 904.
  • the brushless motor 901, the drive circuit 902, the controller 903, the power supply circuit 904, and the power supply 905 are electrically connected to constitute the circuit system 900 of the lawn mower 100.
  • the brushless motor 901 includes three-phase Y-connected windings. Of course, the three-phase windings may be connected in a delta connection.
  • the brushless motor 901 outputs power to drive the grass head 110 to rotate to cut vegetation.
  • the brushless motor 901 includes a stator, a rotor 121a, a motor shaft and windings.
  • the motor shaft directly serves as the drive shaft 122.
  • the rotor 121a includes magnetic materials such as permanent magnets and magnetic steel sheets.
  • the rotor 121a is fixedly connected to the drive shaft 122 so that the rotor 121a As a result, the drive shaft 122 is driven to rotate, thereby driving the grass head to rotate.
  • the stator has an iron core and a stator winding arranged on the stator core. After the stator winding is energized, a magnetic field is generated to drive the rotor to rotate.
  • the brushless motor 901 has three-phase windings, which are a first-phase winding A, a second-phase winding B, and a third-phase winding C, respectively.
  • the driving circuit 902 is electrically connected to the brushless motor 901 to drive the brushless motor 901 to output power.
  • the driving circuit 902 is specifically electrically connected to the three-phase winding of the brushless motor 901, and drives the brushless motor 901 to operate.
  • the driving circuit 902 specifically includes a switching circuit, and the switching circuit is used to drive the brushless motor 901 according to the control signal of the controller 903.
  • the driving circuit 902 adopts a three-phase bridge circuit, including three bridge arms, each of which is provided with two switching elements, and two power transistors on the same bridge arm from the three bridge arms A branch is drawn between them and connected to the three-phase winding of the brushless DC motor respectively.
  • the driving circuit 902 includes switching elements VT1, VT2, VT3, VT4, VT5, VT6, the switching elements VT1, VT2, VT3, VT4, VT5, VT6 constitute a three-phase bridge circuit, respectively
  • Switching elements VT1 ⁇ VT6 can use field effect transistors, IGBT transistors, etc.
  • each switching element is electrically connected to the control signal output terminal of the controller 903, and the drain or source of each switching element is electrically connected to the winding of the brushless motor 901.
  • the switching elements VT1 to VT6 change the on-state according to the control signal output by the controller 903, turn on the winding circuit where the duty cycle is located, and change the voltage state loaded on the winding of the brushless motor 17, so that the corresponding winding When current flows, the brushless motor 901 is driven to operate.
  • the control signal of the controller 903 can control the current or voltage of the brushless motor by controlling the switching elements VT1 to VT6 at the duty ratio, thereby controlling the rotation speed of the brushless motor 901.
  • the driving circuit 902 has multiple driving states. In one driving state, the stator winding of the brushless motor 901 generates a magnetic field.
  • the controller 903 is configured to be based on the rotor of the brushless motor 901. The rotation position outputs a corresponding control signal to the drive circuit 902 to switch the drive state of the drive circuit 902, thereby changing the state of the voltage loaded on the windings of the brushless motor 901, and generating an alternating magnetic field to drive the rotor to rotate, thereby realizing the brushless The motor 17 is driven.
  • the controller 903 is electrically connected to the driving circuit 902 for outputting control signals to control the driving circuit 903 to work.
  • the controller 902 includes a dedicated control chip (eg, MCU, Microcontroller Unit).
  • the controller 902 can control the circuit state of the entire machine and realize various electronic functions, such as motor soft start and electronic braking.
  • the power supply circuit 904 is mainly used to adjust the voltage from the power supply 905 so that the controller 903 can obtain a suitable power supply.
  • the power supply 905 is mainly used to supply power to the entire lawnmower 100. As one of the solutions, the power supply 905 is a rechargeable battery Pack 170.
  • a physical switch 906 can be provided between the controller 903 and the power circuit 904, which can be controlled by the user to turn on or off the electrical connection between the controller 903 and the power circuit 904, so that the controller 903 can not drive the brushless motor 901.
  • the physical switch 906 can be used as the main control switch of the lawn mower 100 for the user to operate to control whether to start the brushless motor 901.
  • the physical switch 906 may be associated with the operating device 130, and the physical switch 906 may be specifically associated with one of the operating members of the operating device 130.
  • the physical switch 906 is associated with the first of the operating device 130.
  • the operation members 131 are connected in association, and can be triggered by the first operation member 131, and when the user operates the first operation member 131, the physical switch 906 can be triggered to be turned on or off.
  • the physical switch 906 is triggered to be turned on, and the controller 903 and the power circuit 904 are electrically connected.
  • the controller In the cutting mode, the controller outputs a control signal to make the brushless motor 901 rotate forward at a relatively high speed to perform the grassing operation.
  • the lawn mower 100 further includes a control switch for placing the controller 903 in the first control mode or the second control mode.
  • the control switch is a signal switch 907.
  • the signal switch can send out different signals 907, and the controller 903 can output different control modes according to the signals sent by the signal switch 907.
  • the brushless motor 901 has different rotation states. Therefore, the signal switch 907 can be used as an operation piece for the user to select the mode, so that the user can select the cutting mode or the automatic winding mode.
  • the controller 903 controls the drive circuit 902 in the first control mode to operate the brushless motor 901 at the first speed.
  • the controller 903 The drive circuit 902 is controlled in a second control mode different from the first control mode to operate the brushless motor 901 at a second rotation speed lower than the first rotation speed.
  • the controller 903 rotates the brushless motor 901 in the first direction in the cutting mode; the controller 903 rotates the brushless motor 901 in the second direction opposite to the first direction in the automatic winding mode.
  • the signal switch 907 sends a first signal.
  • the user controls the physical switch 906 to power on the controller 903.
  • the controller 903 is in the first control mode according to the received first signal, and outputs a control signal to
  • the driving circuit 902 rotates the brushless motor 901 forward at a higher first rotation speed.
  • the signal switch 907 sends a second signal different from the first signal, and the controller 903 is in the second control mode according to the second signal, and outputs a control signal to make the brushless motor 901 at a lower
  • the lawn mower 100 enters the automatic winding mode to perform automatic winding.
  • the signal switch 907 may be associated with the operating device 130 and triggered by the operating device 130.
  • the signal switch 907 may specifically be associated with the second operating member 132 of the operating device 130 when the user operates the second operating member 132
  • the signal switch 907 can be triggered, and the signal switch 907 outputs the first signal or the second signal.
  • the signal switch 907 outputs the first signal when the second operating member 132 is not operated and is in the initial state, and the trigger signal when the second operating member 132 is operated and is in the second preset operating state
  • the switch 907 outputs a second signal, and the controller 903 is in the second control mode according to the second signal.
  • the output control signal causes the brushless motor 901 to reversely rotate at a lower speed, and the lawnmower 100 enters the automatic winding mode.
  • the control of the rotation speed it can be achieved by changing the duty ratio of the control signal that the controller 903 outputs to the drive circuit 902 in the first control mode and the second control mode, and the controller 903 can output the duty comparison in the first control mode
  • the high control signal makes the brushless motor 901 have a higher first rotation speed. At this time, the lawn mower 100 is in the cutting mode to perform the grassing operation.
  • the controller 903 In the second control mode, the controller 903 outputs a control signal with a relatively low duty.
  • the brushless motor 901 has a lower second rotation speed. At this time, the lawn mower 100 is in the automatic winding mode to perform automatic winding.
  • the range of the ratio of the first rotation speed to the second rotation speed is 10 or more and 100 or less.
  • the first rotation speed is 5800 rpm
  • the second rotation speed is 100 rpm
  • the direction of the second rotation speed is opposite to the direction of the first rotation speed.
  • the lawn mower 100 further includes a detection device 908, which is used to detect the current of the brushless motor 901.
  • a detection device 908 which is used to detect the current of the brushless motor 901.
  • the controller 903 can determine whether it is taut according to the current threshold or the threshold of the current slope to stop the brushless motor 901 in the automatic winding mode.
  • the load of the brushless motor 901 becomes larger due to the increase in the mass of the grass rope 101, which makes the current of the brushless motor 901 also increase, so a current threshold can also be set Determine whether the winding is complete.
  • a current threshold can also be set Determine whether the winding is complete.
  • the speed of the brushless motor 901 will also decrease, so you can also set a speed threshold or speed slope threshold as a standard for whether the winding is completed, when the speed drops faster or the speed drops to a certain level
  • the controller 903 determines that the automatic winding is completed.
  • a position sensor may be used to determine the position and state of the mowing rope to end the automatic winding mode.
  • the controller 903 can be reversed to start the automatic winding mode first. Characterization of a large load, such as a large current or a low speed, the controller 903 determines that the current situation is not suitable for running the automatic winding mode, and then stops driving the brushless motor 901, and prompts the user by sound or light signal.
  • the controller 903 can determine the load of the brushless motor 901 according to the rotation speed or current of the brushless motor 901, thereby determining when the winding is terminated and whether it is currently suitable for automatic winding.
  • the related art brushless motor 901 usually also includes a position measuring unit for detecting or estimating the position of the rotor of the brushless motor 901, and the controller 903 outputs a corresponding control signal to the driving circuit 902 according to the position of the rotor to change the conduction
  • the switching element and the conductive winding change the direction of the magnetic field and drive the rotor to continue to rotate.
  • This control method is based on the rotor position to control the conductive winding, thereby changing the direction of the magnetic field and driving the rotor to continue to rotate.
  • the brushless motor 901 operates in reverse low speed in the automatic winding mode, and it is necessary to ensure that the torque generated by the brushless motor 901 is sufficient to automatically wind the grass rope onto the spool 111.
  • the spool 111 is formed with a first inclined surface 111h
  • the head housing 112 is formed with a second inclined surface 112j
  • the first inclined surface 111h and the first The two inclined surfaces 112j are inclined to the normal plane of the central axis 110a.
  • the first inclined surface 111h and the second inclined surface 112j are in contact with each other and relatively slide so that the spool 111 and the head housing 112 can relatively rotate.
  • the transmission surface between the spool 111 and the head housing 112 adopts a slanted surface design, which allows the spool 111 and the head housing 112 to be driven in one direction only, that is, in the cutting mode, the brushless motor 901 rotates in the first direction
  • the spool 111 and the head housing 112 can rotate synchronously, in the automatic winding mode, when the brushless motor 901 rotates in the first direction opposite to the first direction, the spool 111 and the head housing 112 can rotate relative to each other due to the slope slip .
  • the spool 111 is formed with a plurality of first meshing teeth 111a arranged circumferentially around the central axis 110a; the head housing 112 is formed with a plurality of first meshing teeth 112f that cooperate with the plurality of first meshing teeth 111a; the first meshing teeth 111a are formed There is a first inclined surface 111h, the first mating tooth 112f is formed with a second inclined surface 112j, and the first inclined surface 111h and the second inclined surface 112j are inclined to the normal plane of the central axis 110a.
  • the first meshing teeth 111a and the first mating teeth 112f can only be driven in one direction, and when relatively rotated in the opposite direction, the inclined plane slips, which will cause automatic winding
  • the resistance to the rotation of the spool 111 relative to the head housing 112 exhibits a fluctuating state, that is to say, in the automatic winding mode, the resistance to the change of the rotation of the spool 111 relative to the head housing 112, specifically the change
  • the resistance is a kind of periodic fluctuation resistance, therefore, the motor load fluctuation is large.
  • the lawnmower 100 in the automatic winding mode has large load fluctuations and large rotor speed fluctuations, which may damage the brushless motor 901, the spool 111, and the head housing 112, and may cause unstable winding speed 2.
  • the winding process is not smooth, not conducive to winding, and may damage the motor, spool and head shell.
  • the lawnmower 100 of the present application can achieve a stable low-speed, high-torque motor control effect in an automatic winding mode, and the winding speed is more stable.
  • the controller 903 outputs a control signal according to at least one of a given voltage and a given current to control the drive circuit 902 to make the motor 121 run at a substantially constant speed, and the motor 121 drives At least one of the spool 111 and the head case 112 is configured to relatively rotate the spool 111 and the head case 121 to automatically wind the grass rope 101 to the spool 111.
  • the motor 121 specifically selects the brushless motor 901.
  • the resistance of the automatic winding may be different due to the uneven material of the grass rope or the different periods before, during, and after the automatic winding. Therefore, the resistance of the brushless motor 901 The speed may change slightly. Therefore, in the application, when the amount of change in the rotation speed of the brushless motor 901 is within 10%, the rotation speed of the brushless motor 901 is considered to be substantially constant.
  • the motor 121 drives at least one of the spool 111 and the head housing 112 at a substantially constant speed
  • the spool 111 and the head housing 112 are subjected to varying resistance, and at least one of a given voltage and a given current can
  • the controller 903 is caused to output a control signal that causes at least one of the spool 111 and the head housing 112 to overcome the resistance with the largest resistance value among the changed resistances.
  • the motor 121 drives the spool 111 to rotate, and the spool 111 receives resistance to change when the spool 111 rotates relative to the head housing 112, and when the spool 111 rotates relative to the head housing 112
  • the controller 903 to output a control signal that causes the spool 111 to overcome the greatest resistance among the changed resistances.
  • the motor 121 drives the head housing 112 to rotate, and the head housing 112 is subjected to a variable resistance when rotating relative to the bobbin 111, and the amplitude of at least one of a given voltage and a given current It is possible for the controller 903 to output a control signal that causes the head case 111 to overcome the greatest resistance among the changed resistances.
  • the motor 121 drives the head housing 112 and the spool 111 to rotate. There is a speed difference between the head housing 112 and the spool 111, so that the head housing 112 and the spool 111 rotate relative to each other, and the head housing 112 and the spool 111 rotate relative to each other.
  • the controller 903 When subjected to varying resistance, the amplitude of at least one of the given voltage and the given current enables the controller 903 to output a control signal that causes at least one of the spool 111 and the head housing 112 to overcome the maximum resistance among the changed resistance.
  • the controller 903 outputs a control signal according to at least one of a given voltage and a given current to control the drive circuit 902 to generate a rotating magnetic field in the brushless motor 901.
  • the rotating magnetic field can drive the rotor to rotate, and the rotor rotates synchronously with the rotating magnetic field.
  • At least one of the spool 111 and the head housing 112 driven by the rotor rotates synchronously with the rotating magnetic field, the rotating magnetic field operates at a substantially constant speed, thereby causing the motor 121 to operate at a substantially constant speed, and then at least one of the spool 111 and the head housing 112 to The operation is performed at a substantially constant speed, so that the speed at which the grass rope 101 is automatically wound to the spool 111 is also substantially constant, and the winding speed is more stable.
  • the motor 121 drives the spool 111 to rotate relative to the head housing 112, and the controller 903 outputs a control signal according to a given voltage to control the driving circuit 902 so that the brushless motor 901 basically Running at a constant speed, the amplitude of a given voltage enables the controller 903 to output a control signal that can overcome the greatest resistance among the changing resistances when the spool 111 is rotated relative to the head housing 112.
  • the lawn mower 100 further includes a PWM signal determination module 910, and the PWM signal determination module 910 is set in the controller 903, and the PWM signal determination module 910 is used to calculate and determine the controller according to a given voltage
  • the PWM signal output by 903 enables the spool 111 to overcome the greatest resistance among the changing resistances. That is to say, the PWM signal determination module 910 is used to generate a PWM signal that drives the target rotating magnetic field of the rotor, specifically the pulse width and switching point of the PWM signal.
  • the controller 903 further includes a PWM generation module 920, the input terminal of the PWM generation module 920 is connected to the output terminal of the PWM signal determination module 910, and the PWM generation module 920 is connected to the drive circuit 902.
  • the PWM generating module 920 is used to generate a PWM signal according to the PWM signal determined by the PWM signal determining module 910 to control the driving circuit 902 to generate a target rotating magnetic field for the conducting winding, and the target rotating magnetic field drives the rotor to rotate.
  • the controller 903 further includes a power driving module 930, and the PWM generating module 920 is connected to the driving circuit 902 through the power driving module 930, and the power driving module 930 is used to amplify the PWM signal of the PWM generating module to be able to drive the driving circuit
  • the switching element of 902 is turned on.
  • the PWM signal determination module 910 includes: a voltage vector specifying unit 911 for specifying a target voltage vector that the PWM signal determination module 910 needs to synthesize; a vector time action unit 912 whose input terminal is associated with a voltage vector given order Unit 911 is connected, and its output terminal is connected to the vector switching point unit 913, and the vector time action unit 912 determines the action time of the basic voltage vector and the zero vector of the synthesized target voltage vector according to the target voltage vector given by the voltage vector given unit 911 ;
  • Vector switching point unit 913 which is connected to the vector time action unit 912, is used to determine the time point that the PWM signal needs to be switched according to the action time of the basic voltage vector and the zero vector output by the vector time action unit 912, the vector switch point unit 913 includes Timer.
  • the PWM generating module 920 generates a corresponding PWM signal according to the PWM signal determined by the PWM signal determining module 91 and capable of generating a target rotating magnetic field that drives the rotor to rotate, and the PWM signal is used to control the switching element of the driving circuit 902 to turn on the corresponding winding to generate the The target magnetic field corresponding to the target voltage vector.
  • the target voltage vector given by the voltage vector given unit 911 is a rotation vector in a counterclockwise or clockwise direction
  • the corresponding target magnetic field is a rotating magnetic field in a counterclockwise or clockwise direction.
  • the rotating direction of the rotating magnetic field is related to the rotating direction of the brushless motor 901 in the automatic winding mode.
  • the countless motor 901 rotates in the reverse direction, and the rotor rotates in the reverse direction.
  • the target magnetic field is a rotating magnetic field rotating in a counterclockwise direction.
  • the magnitude of the target voltage vector given by the voltage vector given unit 911 is sufficient to overcome the maximum resistance of the bobbin 111 when it rotates relative to the head housing 112.
  • the rotating magnetic field generated by the winding can drive the rotor to continue to rotate at a constant speed, thereby making the bobbin 111
  • the winding speed is stable, which can avoid large load fluctuations in the automatic winding mode and damage the brushless motor 901, the spool 111 and the head housing 112, as well as the problems of unstable winding speed and unsmooth winding process, which is not conducive to winding line.
  • the winding speed of the bobbin 111 is synchronized with the rotating speed of the rotating magnetic field generated by the winding, and the rotational speeds of the two are equal or substantially equal.
  • the magnitude of the target voltage vector given by the voltage vector given unit 911 is related to the power supply voltage of the power supply of the lawnmower 100.
  • the ratio of the given voltage to the power supply voltage ranges from 0.1 to 0.5.
  • the range of the ratio of the amplitude of the target voltage vector to the amplitude of the power supply voltage is: 0.1 to 0.5.
  • the battery pack 170 is used as the power source.
  • the amplitude of the target voltage vector is 10% to 50% of the rated voltage of the battery pack 170.
  • the amplitude of the target voltage vector can be 11V.
  • the amplitude of the target voltage vector can be achieved by setting the duty cycle of the PWM signal.
  • each sector contains two basic voltage vectors u i
  • voltage vector given unit 911 A given target voltage vector U s falls in a sector, which is synthesized by two basic voltage vectors u i at the sector boundary, the basic voltage vector u i is the voltage vector of the winding, and the adjacent basic voltage vector u i 60° apart.
  • the target voltage vector given by the target voltage vector given unit 911 is U S is a rotation vector in a counterclockwise or clockwise direction, and the corresponding target magnetic field is a rotating magnetic field in a counterclockwise or clockwise direction.
  • the amplitude of the target voltage vector U s is obtained through trial and error. The value should be selected so that when the spool 111 rotates relative to the head housing 112, it can overcome the maximum resistance and continue to rotate at a substantially constant speed.
  • the target voltage vector can be defined as Considering different transformations, k can take different values, such as constant power and constant voltage and current amplitude.
  • the value of k is taken as 2/3, then the target voltage vector U S can be expressed as:
  • a first leg 902a, a second leg 902b, 902c of the three six switching elements of the third bridge arm leg co-eight switching patterns may be formed with S A, S B and S c mark the status of the three bridge arms respectively, and the state of the bridge arm is 1 when the upper arm switching element (VT1, VT3, VT5) of each bridge arm is turned on, and the lower bridge arm switching element (VT4, VT6 , VT2) When the bridge arm is turned on, the state of the bridge arm is 0, so that the driving circuit 902 has eight switching modes.
  • the vector action time unit 912 is used to calculate the time to obtain the action of the basic voltage vector and the zero vector according to the target voltage vector given by the target voltage vector given unit 911.
  • the target voltage vector U S is located in sector III, for example, the basic voltage vectors u 4 , u 6 , u 0 and u 7 are to be synthesized in a two-phase stationary reference coordinate system ( ⁇ , ⁇ ) .
  • the angle between U S and u 4 be ⁇ , from the principle of volt-second balance and the sine theorem, we can get:
  • T is the sampling period, usually the PWM modulation period
  • the action time of the basic voltage vector u i of the synthesized target voltage vector U S can be determined by the above method, when the synthesized target voltage vector is needed When U S is located in different sectors, the calculation is as above.
  • the operation time of the basic voltage vector u i in each sector can be obtained through calculation. Let the time when the two basic voltage vectors u i of each sector act be T 1 , T 2 . Thus, the operation schedule of the basic voltage vector u i can be obtained as shown in Table 2 below. Thus, the time when the basic voltage vector and the zero vector of the vector action time unit 912 are applied
  • the brushless motor 901 operates according to the control signal modulated by the PWM signal determination module 910. Its working principle is: when the drive circuit 902 outputs a certain basic voltage vector u i according to the control signal modulated by the PWM signal determination module, the flux linkage space vector ⁇ s is formed , and ⁇ s can be expressed as:
  • ⁇ s0 is the initial flux linkage space vector
  • ⁇ t is the action time of U i .
  • u i is a non-zero voltage vector (u 1 ⁇ u 6 )
  • the flux linkage space vector ⁇ s starts from the initial position, along the corresponding target voltage vector U S direction,
  • u i is a zero-voltage vector (u 0 and u 7 )
  • ⁇ s ⁇ s0
  • the motion of the flux linkage space vector is suppressed.
  • a reasonable choice of the application sequence and action time of six non-zero vectors can make the flux linkage space vector rotate clockwise or counterclockwise to form a flux linkage trajectory of a certain shape.
  • the magnetic flux trajectory should be close to a regular polygon or a circle.
  • the motion of ⁇ s can be adjusted The speed, thereby adjusting the speed of the rotating magnetic field, thereby driving the bobbin 111 to rotate relative to the head housing 112 for winding.
  • the rotor of the brushless motor 901 is rotating clockwise at high speed, then in the automatic winding mode, the rotor of the brushless motor 901 is rotating counterclockwise at low speed, and the corresponding flux linkage space vector is modulated by the PWM modulated ⁇ s rotates counterclockwise.
  • the basic voltage vector u i of the synthesis target voltage vector U S can also be directly given, and the basic voltage vector u i can synthesize the desired target voltage vector U S.
  • the given basic voltage vector u i can be characterized by the on-time or duty cycle of the corresponding winding in one cycle.
  • each PWM modulation period there are five switching states S A , S B , and S C , and they are symmetric about the center of the period.
  • the zero vectors u 0 and u 7 need to be inserted in the middle of the PWM period. Which one of u 0 and u 7 to use depends on the rotation direction and the principle of the least number of switching actions. For example, in sector III, if the direction of rotation is counterclockwise, u 4 moves first, u 6 then moves, and so on.
  • the operation time can be directly from the data in Table 2, and then select the zero vector to make the switch The least number of times.
  • T 0 /T 7 TT 1 -T 2 .
  • Table 4 the schematic diagram of the operation of the switching element of the driving circuit 902 generated by the PWM generating module 920 in each sector is shown in Table 4.
  • the controller 903 also includes a vector switching point unit 913, which includes a timer, which is set to a continuous up/down counting mode, which is used to time the time when the calculated basic voltage vector and zero vector act To determine the vector switching point, the vector switching point corresponds to the switching point of the PWM signal.
  • a vector switching point unit 913 which includes a timer, which is set to a continuous up/down counting mode, which is used to time the time when the calculated basic voltage vector and zero vector act To determine the vector switching point, the vector switching point corresponds to the switching point of the PWM signal.
  • the present application also discloses a control method for the lawn mower 100.
  • the lawn mower 100 includes the above-mentioned grass head 110, a brushless motor 901 driving the grass head 110, a drive circuit 902 driving the brushless motor 901 to operate, and controlling the drive Controller 903 of the circuit;
  • the control method of the lawn mower 100 includes: in the automatic winding mode, outputting a control signal to the driving circuit 902 according to at least one of a given voltage and a given current to make the rotation speed of the brushless motor 901 substantially constant.
  • the grass head 110 includes a spool 111 and a head housing 112.
  • the spool 111 is used to wind the grass rope 101, and the head housing 112 is used to accommodate the spool 111.
  • the spool 111 and the head housing 112 are subjected to varying resistance; At least one of a constant voltage and a given current enables at least one of the spool 111 and the head housing 112 to overcome the resistance with the largest resistance value among the changing resistances.
  • control method of the lawn mower 100 specifically includes:
  • Step S11 The target voltage vector is given.
  • the target voltage vector Before the target voltage vector is given, it is necessary to determine the maximum resistance encountered when at least one of the spool 111 and the head casing 112 encounters relative rotation between the spool 111 and the head casing 112, so as to determine the maximum resistance to be overcome. Experimentally obtained. After the maximum resistance is determined, the given target voltage vector can be determined.
  • the target voltage vector U s is equal to the amplitude of the given voltage, and it enables the controller 903 to output a control signal such that at least one of the spool 111 and the head housing 112 is sufficient to overcome the maximum resistance, so that in the automatic winding mode
  • the speed of the brushless motor 901 is constant and the winding speed is stable.
  • the given target voltage vector U s may be stored in a memory in advance, and the voltage vector giving unit 911 serves as a memory that stores the given target voltage vector U s .
  • Step S12 Determine a basic voltage vector and a zero vector that synthesize the target voltage vector.
  • the position of the sector where the target voltage vector U s is located can be determined, so that two basic voltage vectors u i located on the boundary of the sector can be obtained.
  • the basic voltage vector u i and the zero vector synthesized by the target voltage vector U s can be obtained.
  • the two basic voltage vectors u i and the zero vector may also be directly stored in the voltage vector given unit 911 in advance, or may be obtained through comparison and calculation according to the target voltage vector u i . Assuming that the synthesized voltage vector falls in sector I, the equivalent conditions are as follows:
  • A, B, and C are introduced.
  • the values of A, B, and C are determined according to the two components u ⁇ and u ⁇ of the target voltage vector U s to be synthesized, which has the following relationship:
  • the position of the sector N A+2B+4C.
  • N takes different values, the corresponding sector position is shown in FIG. 12, so that given a target voltage vector U s , the sector in which it is located can be determined.
  • two basic voltage vectors can be determined on the sector boundaries for the zero vector u i and two base voltage vector U s compositing target voltage vector u i and the zero vector.
  • Step S13 Determine the action time of the basic voltage vector and the zero vector.
  • the vector action time unit 912 After determining the basic voltage vector u i and the zero vector, the vector action time unit 912 needs to determine the time when the basic voltage vector u i and the zero vector act.
  • Step S14 Determine the switching time point of the basic voltage vector and the zero vector
  • the timer of the vector switching point unit 913 is set to the continuous up/down counting mode, which performs the calculation of the action time of the calculated basic voltage vector u i and the zero vector
  • the timing determines the vector switching point, which corresponds to the switching point of the PWM signal.
  • the PWM signal to be generated is determined according to the basic voltage vector, the zero vector, and the switching time point of the basic voltage vector and the zero vector.
  • Step S15 Generate a PWM signal.
  • the PWM signal generation module 920 generates a PWM signal according to the PWM signal determined by the above process and outputs the PWM signal to the power driving module 930.
  • the PWM signal generated by the PWM signal generation module 920 is shown in Table 4 below.
  • PWMA represents the state of the control signal sent to the switching elements VT1 and VT4 on the first bridge arm 902a.
  • PWMA signal is 1, the upper bridge switching element VT1 is turned on, and when the PWMA signal is 0, then The lower arm switching element VT4 is turned on.
  • PWMB indicates the state of the control signal sent to the switching elements VT3 and VT6 on the second bridge arm 902b.
  • PWMB signal is 1, the upper arm switching element VT3 is turned on, and when the PWMB signal is 0, then The lower arm switching element VT6 is turned on.
  • PWMC indicates the state of the control signals sent to the switching elements VT5 and VT2 on the third bridge arm 902c.
  • the PWMC signal is 1, the upper bridge switching element VT5 is turned on, and when the PWMC signal is 0, the lower bridge arm The switching element VT2 is turned on.
  • the three-phase wave modulation waveform generated during the sampling time T period the basic voltage vector u i and zero vector appear in the order of u 4 , u 6 , u 7 , u 7 , u 6 .
  • the switching states and three-phase waveforms of u 4 , S A , S B , and S c are shown in the third column of Table 4, and the conduction time of each switching element is shown below the three-phase waveform.
  • Step S16 Control the driving circuit with the generated PWM signal to make the brushless motor operate at a substantially constant rotation speed.
  • the power driving module 930 outputs the PWM signal shown in Table 4 to the driving circuit 902, and the driving circuit 902 operates according to the PWM signal output by the controller 903, thereby controlling the brushless motor 901 to drive at least one of the spool 111 and the head housing 112 to overcome Maximum resistance rotation, so that in automatic winding mode, the motor speed is constant, the winding speed is stable, and the control effect of the motor's stable low speed and high torque can be achieved.
  • the user experience is better, which is beneficial to the winding operation and can avoid the spool 111.
  • the controller 903 outputs a control signal according to a given current to control the driving circuit 902 to run the motor 901 at a substantially constant speed.
  • the amplitude enables the controller 903 to output a control signal that causes at least one of the spool 111 and the head housing 112 to overcome the maximum resistance among the changed resistances.

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Abstract

一种打草机（100），包括打草头（110）、无刷电机（901）、驱动电路（902）、控制器（903），打草头（110）包括线轴（111）和头壳（112），打草机具有自动绕线模式，在该模式下，无刷电机（901）驱动线轴（111）和头壳（112）中的至少一个以使线轴（111）和头壳（112）相对转动以将打草绳自动地缠绕至线轴（111），控制器（903）被配置为，在自动绕线模式下，根据给定电压和给定电流中的至少一个输出控制信号至驱动电路使无刷电机的转速基本恒定。该打草机具有自动绕线模式且绕线速度稳定。

Description

打草机以及打草机的控制方法
本申请要求在2018年12月28日提交中国专利局、申请号为201811621277.0的中国专利申请的优先权，以上申请的全部内容通过引用结合在本申请中。
技术领域
本申请涉及一种园林工具，例如涉及一种打草机以及打草机的控制方法。
背景技术
打草机是一种园林工具，用于对草坪进行修剪。打草机包括有打草头，打草头高速转动带动安装在其上的打草绳旋转实现对切割功能。
打草头包括有用于供打草绳缠绕的线轴，在进行打草作业时，打草绳由于磨损而逐渐被消耗。在进行一段时间的作业，用户需要更换新的打草绳，将打草绳缠绕到线轴上。传统的打草绳，用户需要去手动转动线轴以使打草绳缠绕到线轴，操作麻烦，缠绕速度慢，也由于人手在缠绕过程中接触打草头从而带来一定的风险。因此，自动绕线模式的打草机应运而生。具有自动绕线模式的打草机，能够将打草绳自动地缠绕至线轴。在自动绕线模式下，为了便于绕线，需要确保驱动线轴的电机维持稳定的低速状态，相关的打草机，由于受到打草头结构的限制，在自动绕线模式下，负载波动较大，不能维持稳定的低速状态。
发明内容
本申请提供一种具有自动绕线模式且绕线速度稳定的打草机以及打草机的控制方法。
一种打草机，包括：打草头；无刷电机，用于驱动所述打草头转动以切割植被；驱动电路，与所述电机连接，以驱动所述电机输出动力；控制器，与所述驱动电路连接，用于控制所述驱动电路；所述打草头包括线轴和头壳，所述线轴用于缠绕打草绳，所述头壳用于容纳所述线轴；所述打草机具有自动绕线模式，在所述自动绕线模式下，所述无刷电机驱动所述线轴和所述头壳中的至少一个以使所述线轴和所述头壳相对转动以将所述打草绳自动地缠绕至所述线轴；所述控制器被配置为：在所述自动绕线模式下，根据给定电压和给定电流中的至少一个输出控制信号至所述驱动电路使所述无刷电机的转速基本恒定。
在所述自动绕线模式下，所述线轴和所述头壳受到变化的阻力；所述给定电压和所述给定电流中的至少一个能够使所述控制器输出使所述线轴和所述头壳中的至少一个克服所述变化的阻力中阻力值最大的阻力的控制信号。
所述变化的阻力周期性波动。
所述控制器包括：PWM信号确定模块，用于根据所述给定电压计算和确定所述控制器输出的能够使所述线轴和所述头壳中的至少一个克服所述变化的阻力中阻力值最大的阻力的PWM信号；PWM信号生成模块，用于根据所述PWM信号确定模块确定的所述PWM信号生成PWM信号以控制驱动电路。
所述PWM信号确定模块包括：电压矢量给定单元，用于给定目标电压矢量，所述目标电压矢量的幅值与所述给定电压的幅值相等；矢量作用时间单元，用于根据所述电压矢量给定单元给定的所述目标电压矢量确定合成所述目标电压矢量的基本电压矢量和零矢量的作用时间，所述矢量作用时间单元的输入端与所述电压矢量给定单元的输出端连接；矢量切换点单元，用于确定所述基本电压矢量和零矢量的切换时间点，所述矢量切换点单元的输入端与所述矢量作用时间单元的输出端连接。
所述控制器被配置为：在所述自动绕线模式下，根据所述给定电压和给定电流中的至少一个输出控制信号至所述驱动电路以在所述无刷电机内产生旋转磁场，所述线轴和所述头壳中的至少一个与所述旋转磁场基本同步转动。
所述头壳和所述线轴中的至少一个绕中心轴线转动，所述中心轴线与驱动轴的轴线基本重合，所述驱动轴由所述无刷电机驱动从而驱动所述打草头；所述线轴形成有第一斜面，所述头壳形成有第二斜面，所 述第一斜面和所述第二斜面倾斜于所述中心轴线的法平面；在所述自动绕线模式下，所述第一斜面和所述第二斜面相互接触并相对滑动以使得所述线轴和所述头壳能够相对转动。
所述线轴形成有绕所述中心轴线周向排布的多个第一啮合齿，所述第一啮合齿形成有所述第一斜面；所述头壳形成有与所述多个第一啮合齿配合的多个第一配合齿，所述第一配合齿形成有所述第二斜面。
所述多个第一啮合齿中相邻的两个第一啮合齿在所述中心轴线的周向上相互间隔第二尺寸。
所述打草机还具有切割模式；在所述切割模式下，所述第一啮合齿与所述第一配合齿相互止挡；在所述自动绕线模式下，所述第一啮合齿与所述第一配合齿相互接触并相对滑动。
所述多个第一啮合齿中的每个第一啮合齿形成的所述第一斜面沿所述中心轴线的周向方向倾斜；所述多个第一配合齿中的每个第一配合齿形成的所述第二斜面沿所述中心轴线的周向方向倾斜。
所述打草机还具有切割模式，在所述切割模式下，所述线轴和所述头壳同步转动；所述控制器被配置为：在所述切割模式下，以第一控制模式控制所述驱动电路使所述无刷电机以第一转速运行；在所述自动绕线模式下，以第二控制模式控制所述驱动电路使所述无刷电机以第二转速运行；所述第二转速小于所述第一转速。
所述第一转速与所述第二转速的比值的取值范围为：10～100。
所述控制器被配置为：在所述切割模式时，使所述无刷电机以所述第一转速沿第一方向转动；在所述自动绕线模式时，使所述无刷电机以所述第二转速沿第二方向转动；所述第一方向与所述第二方向相反。
所述打草机由供电电源提供电能，所述给定电压与所述供电电源的电压的比值的取值范围为：0.1～0.5。
一种打草机的控制方法，所述打草机具有自动绕线模式，所述打草机包括打草头、驱动所述打草头的无刷电机、驱动所述无刷电机运转的驱动电路、控制所述驱动电路的控制器；所述打草机的控制方法包括：在所述自动绕线模式下，根据给定电压和给定电流中的至少一个输出控制信号至所述驱动电路使所述无刷电机的转速基本恒定。
所述打草头包括线轴和头壳，所述线轴用于缠绕打草绳，所述头壳用于容纳所述线轴；在所述自动绕线模式下，所述线轴和所述头壳受到变化的阻力；所述给定电压和所述给定电流中的至少一个能够使所述线轴和所述头壳中的至少一个克服所述变化的阻力中阻力值最大的阻力。
所述打草机的控制方法包括：给定目标电压矢量，所述目标电压矢量的幅值与所述给定电压的幅值相等；确定合成所述目标电压矢量的基本电压矢量和零矢量；确定所述基本电压矢量和零矢量的作用时间；确定所述基本电压矢量和零矢量的切换时间点；根据所述基本电压矢量、所述零矢量以及所述基本电压矢量和所述零矢量的切换时间点确定PWM信号。
所述头壳和所述线轴中的至少一个绕中心轴线转动，所述中心轴线与驱动轴的轴线基本重合，所述驱动轴由所述无刷电机驱动从而驱动所述打草头；所述线轴形成有第一斜面，所述头壳形成有第二斜面，所述第一斜面和所述第二斜面倾斜于所述中心轴线的法平面；在所述自动绕线模式下，所述第一斜面和所述第二斜面相互接触并相对滑动以使得所述线轴和所述头壳能够相对转动。
所述打草机还具有切割模式，在所述切割模式下，所述线轴和所述头壳同步转动；所述控制器被配置为：在所述切割模式下，以第一控制模式控制所述驱动电路使所述无刷电机以第一转速沿第一方向转动；在所述自动绕线模式下，以第二控制模式控制所述驱动电路使所述无刷电机以第二转速沿第二方向转动运行；所述第二转速小于所述第一转速，所述第二方向与所述第一方向相反。
本申请的打草机以及打草机的控制方法，在打草机处于自动绕线模式下，能够实现电机稳定低速、大扭矩的控制效果，且电机转速不受负载波动影响而基本保持恒定，绕线速度更稳定，用户体验较佳。
附图说明
图1是一种作为实施例的打草机的示意图；
图2是图1中的局部结构示意图；
图3是图2中结构的剖视图；
图4是图2中结构的爆炸图；
图5是图2中结构的另一视角的爆炸图；
图6是图5中头壳的上盖的示意图；
图7是图5中线轴的示意图；
图8是图1中操作装置的示意图；
图9是一种实施方式的打草机的电路框图；
图10是图9中驱动电路的示意图；
图11是图9中控制器的内部框图；
图12是电压空间矢量图；
图13是一种实施方式的打草机的控制方法的流程图。
具体实施方式
以下结合附图和具体实施例对本申请作具体的介绍。
参照图1至图3，作为一种实施方式，打草机100包括打草头110、驱动装置120和操作装置130。
打草头110用于安装和收纳打草绳101，打草绳101的部分收纳在打草头110的内部，打草头101还有一部分伸出打草头110以用于在打草头110旋转时切割植被。操作装置130用于供用户操作以控制打草机100。驱动装置120能驱动打草头110绕一中心轴线110a转动，从而带动打草绳101转动切割植被。
参照图3，驱动装置120包括电机121和驱动轴122。驱动轴122与电机121的转子121a连接，由电机121的转子121a驱动，电机121用于驱动打草头110转动以切割植被。驱动轴122止转连接至打草头110从而驱动打草头110转动。作为一种实施方式，电机121为无刷电机901(图9)，电机121还包括转子121a。在一些实施方式中，所述驱动轴122为电机121的电机轴，中心轴线110a为电机轴的轴线，所述驱动轴122与所述电机121的电机轴机械连接。
打草机100还包括第一壳体150、第二壳体160。第一壳体150的作用在于安装和容纳电机121。打草机100由电源供电，电源可以是直流电源，也可以是交流电源。在本实施方式中，供电电源为电池包170，电池包170作为能量来源至少为打草机100中电机121供电，第二壳体160用于可拆卸地适配电池包170。
第二壳体160内还容纳有电路板，该电路板电连接至电机121使电池包170为电机121供电并对电机121进行控制。连杆组件190连接第一壳体150和第二壳体160。操作装置130固定至连杆组件190。打草机100还包括供用户握持的辅助把手191，辅助把手191固定至连杆组件190。
打草绳101安装至打草头110。护罩180用于实现安全防护的作用，防止打草绳401对用户造成伤害。
参照图3至图5，打草头110包括线轴111和头壳112。
线轴111用于缠绕打草绳101并连至驱动轴122从而能被驱动轴122驱动绕中心轴线110a转动。
头壳112包括上盖112a和下盖112b。打草头110还包括：风扇112c。风扇112c形成有用于产生气流 的扇叶。电机121能够驱动风扇112c转动以产生气流。
在图4和图5所示的方案中还设有一个作为阻尼装置的单向轴承140，单向轴承140的作用是使头壳112与电机121构成单向的转动连接。还设置有一个支承件152，该支承件152与电机121连接并能使驱动轴122穿过，其形成有一个凸台部152a(图5)以支承单向轴承140的内圈。单向轴承140并没有直接连接至头壳112而是设置在支承件152与风扇112c之间，使风扇112c相对支承件152仅能单向的相对转动，又由于风扇112c与头壳112构成止转连接，所以头壳112相对支承件152也仅能单向的转动。
上盖112a形成有第一连接齿112d，风扇112c形成有与第一连接齿112d的第二连接齿112e，第一连接齿112d与第二连接齿112e配合实现上盖112a和风扇112c的同步转动。第一连接齿112d与第二连接齿112e相互配合的导向作用能使头壳112能够相对于风扇112c沿中心轴线110a滑动，并且使风扇112c能随头壳112绕中心轴线110a转动，即风扇112c与头壳112构成止转连接。
打草机100还包括保护罩151。保护罩151固定至第一壳体150。保护罩151至少在中心轴线110a的径向上覆盖风扇112c的扇叶以起到防止草屑缠绕风扇112c。并且保护罩151改变了风扇112c的气流流动方向，使得风扇112c产生的气流能够沿中心轴线110a的径向向外吹出草屑。
驱动轴122直接驱动线轴111转动，头壳112相对线轴111既可以发生相对转动，也可以相对线轴111产生在轴向(即中心轴线110a的方向)相对滑动。
头壳112和线轴111中的至少一个绕中心轴线110a线转动，中心轴线110a与驱动轴122的轴线基本重合，驱动轴122由无刷电机901驱动从而驱动打草头110。
线轴111形成有第一斜面111h，头壳112形成有第二斜面112j，第一斜面111h和第二斜面112j倾斜于所述中心轴线110a的法平面，所述中心轴线110a的法平面垂直于所述中心轴线110a。在自动绕线模式下，第一斜面111h和第二斜面112j相互接触并相对滑动以使得线轴111和头壳112能够相对转动。
作为一种具体地实施方式，线轴111形成有绕中心轴线110a周向排布的多个第一啮合齿111a；头壳112形成有与所述多个第一啮合齿111a配合的多个第一配合齿112f；第一啮合齿111a形成有第一斜面111h，所述第一配合齿112f形成有第二斜面112j，第一斜面111h和所述第二斜面112j倾斜于中心轴线110a的法平面，在自动绕线模式下，第一斜面111h和第二斜面112j相互接触并相对滑动以使得线轴111和头壳112能够相对转动。多个第一啮合齿111a中相邻的两个第一啮合齿111a在中心轴线110a的周向上相互间隔第二尺寸。每个第一啮合齿形成的所述第一斜面111h沿中心轴线110a的周向方向倾斜；每个第一配合齿112f形成的所述第二斜面112j沿所述中心轴线110a的周向方向倾斜。
参照图4至图7，第一啮合齿111a形成于线轴111的上部，第一啮合齿111a为斜齿。第一配合齿112f形成于头壳112内，第一配合齿112f形成于上盖112a。
由于第一啮合齿111a和第一配合齿112f采用斜面设计，使得第一啮合齿111a和第一配合齿112f仅能单向传动，在打草机100处于切割模式下，第一配合齿112f和第一啮合齿111a处于相互止挡状态使线轴111转动时能够带动头壳112同步转动，而在打草机100处于自动绕线模式下，线轴111和头壳112以相反的方向相对转动时，由于斜面而打滑使得第一配合齿112f和第一啮合齿111a能够相对滑动，从而使得线轴111和头壳112可以持续的相对转动。也即是说，在切割模式下，第一啮合齿111a与所述第一配合齿112f相互止挡；在自动绕线模式下，第一啮合齿111a与第一配合齿112f相互接触并相对滑动。
作为可选地，线轴111下部形成有第二啮合齿111b，头壳112内形成有第二配合齿112g，第二配合齿112g形成于下盖112b，第二啮合齿111b和第二配合齿112g形成有斜面。第二啮合齿111b和第二配合齿112g在头壳112处于相对于线轴111的第二轴向位置时能够构成配合，第二啮合齿111b和第二配合齿112g的传动面采用斜面的设计，由于传动面采用斜面设计，第二啮合齿111b和第二配合齿112g之间会出现打滑，所以在头壳112处于相对于线轴111的第二轴向位置时，头壳112并不能被线轴111完全带动，头壳 112还是会相对线轴111转动。
通过上述结构，在电机121反转时，驱动轴122带动线轴111反转，而头壳112因为单向轴承140阻止其反转而使线轴111和头壳112产生相对运动，此时，因为线轴111和头壳112的接触面为斜面的原因，第一啮合齿111a和第一配合齿112f并不能彻底阻碍线轴111和头壳112的相对运动，所以此时线轴111和头壳112能连续的产生相对转动，从而使打草机可以执行自动绕线模式。但由于斜面的原因，第一啮合齿111a和第一配合齿112f虽不能彻底阻碍线轴111和头壳112的相对运动，但会使得线轴111和头壳112受到变化的阻力，该变化的阻力具体为一种周期性波动的阻力。
打草头110还包括弹簧110b，弹簧110b在下盖112b和线轴111之间施加作用力使头壳112被偏压向与线轴111同步转动的轴向位置，此时头壳112处于相对于线轴111的第一轴向位置。
打草头110还包括第一接触件110c和第二接触件110d。弹簧110b设置在第一接触件110d和第二接触件110e之间。弹簧110b可以直接作用于第一接触件110c和第二接触件110d。第一接触件110c和第二接触件110d能够避免弹簧110b对线轴111和头壳112的磨损。第一接触件110d和第二接触件110e为金属件。
打草头110还包括敲击帽110e，敲击帽110e转动连接至下盖112b，敲击帽110e和下盖112b之间设有轴承110f，使敲击帽110e和下盖112b之间可以相对转动，同时，敲击帽110e和下盖112b在轴线110a的方向上是同步运动，也就是说改变敲击帽110e的位置，下盖112b也能随着一同运动，即头壳112会因为敲击敲击帽110e而改变轴向位置。
打草机100在执行切割模式时，用户敲击打草头110，敲击帽110e与地面接触促使头壳112滑动至使第一配合齿112f和第一啮合齿111a脱开配合的位置，从而使它们发生相对转动，敲击使头壳112滑动至相对于线轴111的第二轴向位置，从而使头壳112以较低的相对转速相对线轴111转动，从而使缠绕在线轴111上打草绳101释放一部分至头壳112之外，使打草机100执行一个放线模式。这样的好处在于，在电机121仍以切割模式下的转速转动时，头壳112和线轴111相对转动的速度得到控制，使用户能在每次敲击时不至于放出过量的打草绳101。
敲击帽110e在轴承110f的作用下能相对于下盖112b自由转动，减小打草头110的磨损。弹簧110b对头壳112施加作用力使头壳112相对于线轴111向下运动。上盖112a和线轴111之间设有用于减缓上盖112a和线轴111之间冲击的减震件110g。减震件110g可以为橡胶垫圈。
参照图3，线轴111形成有用于固定打草绳101的内穿线孔111c。头壳112形成有使打草绳101从头壳112的内部穿出至头壳112外部的外穿线孔112h。在切割模式结束时，外穿线孔112h与内穿线孔111c在周向上自动对齐。或者在，打草头110未安装打草绳101，电机121停止时，外穿线孔112h与内穿线孔111c在周向上自动对齐。
线轴111形成有多个内穿线孔111c(图3)，内穿线孔111c的数量为偶数。多个内穿线孔111c在线轴111的轴线110a的周向上均匀分布。第一啮合齿111a的数量与内穿线孔111c的数量对应。同样，第二啮合齿111b的数量与内穿线孔111c的数量对应。在本实施方式中，线轴111形成有6个内穿线孔111c。线轴111形成有6个第一啮合齿111a和6个第二啮合齿111b。所述多个第一啮合齿111a中相邻的两个第一啮合齿111a在轴线110a的周向上相互间隔第二尺寸。
参照图7，线轴111形成有引导开口111d，以引导打草绳101进入内穿线孔111c，引导开口111d沿线轴111的转动轴线的径向逐渐扩大。引导开口111d在轴线110a的周向上的最大尺寸L1大于相连两个第一啮合齿在轴线110a的周向上的最大尺寸L2。
在割草机100执行切割模式时，第一啮合齿111a和第一配合齿112f的传动面的设置使得在电机121停止时，外穿线孔112h与内穿线孔111c在周向上自动对齐。这里所指的对齐是指穿过外穿线孔112h的打 草绳101能被直接地导引进入内穿线孔111c。
线轴111的两端分别形成有第一法兰111e和第二法兰111f。线轴111的中部形成有分隔板111g。第一法兰111e和分隔板111g之间形成有用于缠绕并容纳打草绳101的第一缠绕部；第二法兰111f和分隔板111g之间形成有用于缠绕并容纳打草绳101的第二缠绕部。
在切割模式时，驱动轴122转动带动线轴111转动，线轴111带动上盖112a转动。由上盖112a带动风扇112c转动。单向轴承140的作用下，风扇112c能相对于第二壳体160沿第一方向(参考图2中箭头B所示的方向)转动。此时电机121正向转动带动线轴111、头壳112均沿第一方向转动。
在用户需要补充打草绳101时，用户可以将一根打草绳101的两端分别穿过头壳112的两个相对的外穿线孔112h，然后打草绳101的两端分别伸入至线轴111两个相对的内穿线孔111c。当然用户也可以将两根打草绳101分别插入至两个内穿线孔111c中。此时用户控制打草机100使打草机100执行自动绕线模式，电机121反向转动带动线轴111沿与第一方向相反的第二方向转动，由于单向轴承140的止转作用，风扇112c和头壳112不能沿第二反向转动，而绕线轴111在驱动轴122的带动下能够相对于头壳112沿第二方向转动实现自动绕线。
其原因在于：头壳112与线轴111直接的第一啮合齿111a、第二啮合齿111b与第一配合齿110f、第二配合齿110g形成有倾斜于中心轴线110a的法平面的斜面，在电机121反转时，第一啮合齿111a、第二啮合齿111b的斜面与第一配合齿110f、第二配合齿110g的斜面接触，由于斜面打滑，斜面并不能阻止线轴111和头壳112相对转动，线轴111能够相对于头壳112沿第二方向转动实现自动绕线。
在自动绕线模式下，在线轴111已经缠绕有足够多的打草绳101时，用户需要切断尚未缠绕的过长的打草绳101。打草机100还包括断线装置181(如图1)。断线装置181在自动绕线模式时自动地切断打草绳101。
断线装置181包括断线元件182，打草头110能相对于断线元件182转动。断线元件182固定至护罩180。使打草绳101在自动绕线模式时能被打草头110带动着经过断线元件182，打草绳101张紧后被断线元件182切断。在处于切割模式或者处于放线模式时，断线元件182能够将打草绳101打断，打草绳101的中部被打断，变为两段打草绳101。当然，可以直接在打草绳101绷紧在头壳112外侧时采用敲击的方式敲断打草绳101。
如图8所示，操作装置130包括：第一操作件131和第二操作件132。第一操作件131具有初始状态和第一预设操作状态。第二操作件132具有初始状态和第二预设操作状态。在第一操作件131和第二操作件132分别处于第一预设操作状态和第二预设操作状态时打草机100能启动自动绕线模式。操作装置130包括：第一复位组件133和第二复位组件134。第一复位组件133在用户不操作第一操作件131时使第一操作件131脱离第一预设状态。第二复位组件134在用户不操作第二操作件132时使第二操作件132脱离第二预设状态。用户不操作第二操作件132，而仅操作第一操作件131时，即在第二操作件132不处于第二预设操作状态时，操作第一操作件131使之移动到第一预设操作状态，此时打草机100处于切割模式。
参照图9，打草机100的运行还需依赖于由电路部件组成的电路系统900，作为一种实施方式，电机121选择无刷电机901，打草机100还包括驱动电路902、控制器903、电源电路904。无刷电机901、驱动电路902、控制器903、电源电路904和电源905电连接构成打草机100的电路系统900。其中，无刷电机901包括三相构成Y型连接的绕组，当然，也可以将三相绕组采用采用三角型连接。
无刷电机901输出动力驱动打草头110转动以切割植被。无刷电机901包括定子、转子121a、电机轴和绕组，电机轴直接作为驱动轴122，转子121a包括磁性材料，例如永磁体、磁钢片等，转子121a与驱动轴122固定连接，使得转子121a得以驱动驱动轴122转动，从而驱动打草头转动。定子具有铁芯及绕设于定子铁心上的定子绕组，定子绕组通电后产生磁场以带动转子转动。本实施方式中，所述无刷电机901具有三相绕组，分别为第一相绕组A、第二相绕组B、第三相绕组C。
驱动电路902电连接至无刷电机901，用以驱动无刷电机901输出动力。驱动电路902具体与无刷电机901的三相绕组电连接，驱动无刷电机901运转。驱动电路902具体包括有开关电路，开关电路用于根据所述控制器903的控制信号驱动无刷电机901运转。在本实施方式中，驱动电路902采用三相桥式电路，包括三个桥臂，每个桥臂上设有两个开关元件，从三个桥臂中位于同一桥臂上的两个功率管之间引出一条支路并分别连接到无刷直流电机的三相绕组。
参照图10，作为一种实施方式，驱动电路902包括开关元件VT1、VT2、VT3、VT4、VT5、VT6，开关元件VT1、VT2、VT3、VT4、VT5、VT6组成三相桥式电路，分别为第一桥臂902a、第二桥臂902b、第三桥臂903c，其中VT1、VT3、VT5为上桥臂开关元件，VT2、VT4、VT6为下桥臂开关元件。开关元件VT1～VT6可选用场效应管、IGBT晶体管等。对于场效应管而言，各开关元件的栅极端分别与控制器903的控制信号输出端电性连接，各个开关元件的漏极或源极与无刷电机901的绕组电连接。开关元件VT1～VT6依据控制器903输出的控制信号改变接通状态，以一定的占空比导通所在的绕组电路，改变加载在无刷电机17的绕组上的电压状态，从而使相应的绕组有电流通过，驱动无刷电机901运转。需要说明的是，控制器903的控制信号可以通过控制开关元件VT1～VT6在占空比来控制无刷电机的电流或电压，从而控制无刷电机901的转速。
为了使无刷电机901转动，驱动电路902具有多个驱动状态，在一个驱动状态下无刷电机901的定子绕组会产生一个磁场，相关技术中控制器903被配置为依据无刷电机901的转子转动位置输出相应的控制信号至驱动电路902以使驱动电路902切换驱动状态，从而改变加载在无刷电机901的绕组上的电压的状态，产生交变的磁场驱动转子转动，进而实现对无刷电机17的驱动。
控制器903电连接至驱动电路902，用以输出控制信号控制驱动电路903工作。在一些实施例中，控制器902包括专用的控制芯片(例如，MCU，微控制单元，Microcontroller Unit)。所述的控制器902能够控制整个机器的电路状态，实现各种电子功能，如电机软启动、电子制动等。
电源电路904主要用于调整来自电源905的电压以使控制器903获得合适的电源，电源905主要用于为整个打草机100供电，作为其中一种方案，电源905是一种反复充电的电池包170。
作为可选地，可以在控制器903和电源电路904之间设置一个物理开关906，其能被用户控制以导通或断开控制器903与电源电路904之间的电连接，从而使控制器903无法驱动无刷电机901。
物理开关906可以作为打草机100的主控开关，用于供用户操作以控制是否使无刷电机901启动。在一些实施方式中，物理开关906可以与操作装置130关联连接，物理开关906具体可以与操作装置130其中的一个操作件关联连接，作为一种实施方式，物理开关906与操作装置130的第一操作件131关联连接，可由第一操作件131触发，当用户操作第一操作件131时可触发物理开关906导通或关断。作为一种实施方式，在第一操作件131被操作而处于第一预设操作状态时，触发物理开关906导通，控制器903与电源电路904之间实现电连接，此时打草机100处于切割模式，控制器输出控制信号使无刷电机901以较高的转速正向转动，以进行打草作业。
所述打草机100还包括控制开关，用于使所述控制器903处于所述第一控制模式或所述第二控制模式。作为可选地，该控制开关为信号开关907，用户在操作该信号开关907时能使该信号开关发907出不同信号，控制器903可以根据信号开关907所发出的信号输出不同的控制模式使无刷电机901具有不同的转动状态。因此，信号开关907可以作为用户进行模式选择的操作件，以使用户能选择切割模式还是自动绕线模式。
在切割模式下，线轴111和头壳112同步转动，控制器903在切割模式时以第一控制模式控制驱动电路902使无刷电机901以第一转速运转，控制器903在自动绕线模式时以异于第一控制模式的第二控制模式控制驱动电路902使所述无刷电机901以低于第一转速的第二转速运行。控制器903在切割模式时使无刷电机901向第一方向转动；控制器903在自动绕线模式时使无刷电机901向与第一方向相反的第二方向 转动。
当用户选择切割模式时，信号开关907发出第一信号，此时用户再控制物理开关906使控制器903通电，控制器903根据接收到的第一信号，处于第一控制模式，输出控制信号至驱动电路902以使无刷电机901以较高的第一转速正向转动。当用户选择自动绕线模式时，信号开关907发出异于第一信号的第二信号，控制器903根据第二信号，处于第二控制模式，输出控制信号使无刷电机901以较低的第二转速反向转动，打草机100进入自动绕线模式，进行自动绕线。
在一些实施方式中，信号开关907可以与操作装置130关联连接，由操作装置130触发，信号开关907具体可以与操作装置130的第二操作件132关联连接，当用户操作第二操作件132时可触发信号开关907，信号开关907输出第一信号或第二信号。作为一种实施方式，在第二操作件132没有被操作而处于初始状态时，信号开关907输出第一信号，而在第二操作件132被操作而处于第二预设操作状态时，触发信号开关907输出第二信号，控制器903根据第二信号，处于第二控制模式，输出控制信号使无刷电机901以较低的转速反向转动，打草机100进入自动绕线模式。
当然，也可以采用两个物理开关或两个信号开关的方案，使它们分别实现模式切换和无刷电机901启动的控制。
对于转速的控制，可以通过改变控制器903在第一控制模式和第二控制模式输出至驱动电路902的控制信号的占空比来实现，控制器903可以在第一控制模式时输出占空比较高的控制信号使无刷电机901具有较高的第一转速，此时打草机100处于切割模式，进行打草作业，在第二控制模式时控制器903输出占空比较低的控制信号使无刷电机901具有较低的第二转速，此时打草机100处于自动绕线模式，进行自动绕线工作。
作为一种实施方式，第一转速和第二转速的比值的取值范围为大于等于10小于等于100。例如，第一转速为5800rpm，第二转速为100rpm，且第二转速的方向与第一转速的方向相反。
另外，为了实现绕线的自动停止，打草机100还包括检测装置908，检测装置908用于检测无刷电机901的电流，当绕线结束时，打草绳101会绷紧，无刷电机901的电流会突然增大，控制器903可以根据电流阈值或电流斜率的阈值判断是否绷紧从而使在执行自动绕线模式的无刷电机901停机。
另外，随着打草绳101的缠绕，无刷电机901的负载由于打草绳101质量的增加而变大，这使得无刷电机901的电流也会增大，因此也可以设置一个电流阈值来判断绕线是否完成。同样地，由于负载的增加，无刷电机901的转速也会下降，因此也可以设置一个转速的阈值或转速斜率的阈值作为是否绕线完成的标准，当转速下降较快时或转速下降到一定程度时，控制器903即判断完成自动绕线。
或者，也可采用位置传感器或光学传感器等判断打草绳的位置和状态从而结束自动绕线模式。
另外，根据同样的原理，为了防止在打草头中仍存储有打草绳101时，用户误操作启动自动绕线模式，可以使控制器903先反转启动自动绕线模式，如果此时出现负载较大的表征，比如电流较大或转速较低，则控制器903则判断当前情况不适合运行自动绕线模式，然后停止驱动无刷电机901，并采用声音或光信号等方式提示用户。
总之，控制器903可以根据无刷电机901的转速或电流判断无刷电机901的负载情况，从而判断何时绕线终止以及当前是否适于进行自动绕线。
相关技术的无刷电机901，通常还包括一个位置测算单元，用于检测或估算无刷电机901的转子的位置，控制器903根据转子的位置输出相应的控制信号至驱动电路902，改变导通的开关元件和导通的绕组，从而改变磁场方向，驱动转子持续转动。这样的控制方式，是根据转子位置来来控制导通绕组，从而改变磁场方向，带动转子持续转动。
在本申请中，打草机100在自动绕线模式下无刷电机901反向低速运行，且需保证无刷电机901产生 的扭矩足以使得打草绳自动缠绕至线轴111上。
本申请的打草机100，由于头壳112和线轴111中的至少一个绕中心轴线110a转动，线轴111形成有第一斜面111h，头壳112形成有第二斜面112j，第一斜面111h和第二斜面112j倾斜于中心轴线110a的法平面。在自动绕线模式下，第一斜面111h和第二斜面112j相互接触并相对滑动以使得线轴111和头壳112能够相对转动。
也即是说，线轴111和头壳112之间的传动面采用斜面设计，该斜面使得线轴111和头壳112仅能单向传动，即在切割模式下，无刷电机901沿第一方向转动时，线轴111和头壳112能够同步转动，而在自动绕线模式下，无刷电机901沿与第一方向相反的第一方向转动时，由于斜面打滑，线轴111和头壳112能够相对转动。
线轴111形成有绕中心轴线110a周向排布的多个第一啮合齿111a；头壳112形成有与多个第一啮合齿111a配合的多个第一配合齿112f；第一啮合齿111a形成有第一斜面111h，第一配合齿112f形成有第二斜面112j，第一斜面111h和第二斜面112j倾斜于中心轴线110a的法平面。
按照这样的方式，由于斜面的设置，使得第一啮合齿111a和第一配合齿112f仅能单向传动，而在以相反的方向相对转动时，由于斜面而打滑，这样会使得在自动绕线模式下，线轴111相对头壳112转动所受到的阻力呈现一种波动状态，也即是说，在自动绕线模式下，线轴111相对头壳112转动所受到的变化的阻力，具体的是变化的阻力是一种周期性波动的阻力，因而，电机负载波动较大。
在线轴111相对头壳112转动过程中，第一配合齿110f达到第一啮合齿111a的斜面的最高点位置时，线轴111相对头壳112转动所受到的阻力最大，而当第一配合齿110f越过第一啮合齿111a的斜面的最高点向最低点移动时，线轴111相对头壳112转动所受到的阻力突然减小到最小。
如果将上述采用相关技术的无刷电机的控制方式(根据转子的位置改变导通的开关，从而改变导通的绕组来改变磁场的方向，使得转子能够保持持续转动)应用到打草机100的自动绕线模式中，当线轴111相对头壳112转动受到的阻力最大时，负载电流增大，转子转速提高，而当线轴111跃过该阻力最大点后，线轴111相对头壳112转动受到的阻力突然减小，负载电流减小，转子转速又会降低。这样，会使得打草机100在自动绕线模式下，负载波动较大，转子转速波动较大，这样可能会损坏无刷电机901、线轴111和头壳112，且会导致绕线速度不稳定、绕线过程不顺畅，不利于绕线，且可能损害电机、线轴和头壳。
而本申请的打草机100能够在自动绕线模式下，实现稳定低速、大扭矩电机控制效果，绕线速度更稳定。
本申请的打草机100在自动绕线模式下，控制器903根据给定电压和给定电流中的至少一个输出控制信号以控制驱动电路902使电机121以基本恒定的转速运行，电机121驱动线轴111和头壳112中的至少一个以使线轴111和头壳121相对转动从而将打草绳101自动地缠绕至线轴111。电机121具体选择无刷电机901。在自动绕线过程中，可能会由于打草绳材料的不均匀、或自动绕线的前、中、后的不同时期，自动绕线所受到的阻力可能会不同，因此，无刷电机901的转速可能会有较小的变化。因此，在申请中，当无刷电机901的转速的变化量在10％以内时，便认为无刷电机901的转速基本恒定。
在自动绕线模式下，电机121以基本恒定的转速驱动线轴111和头壳112中的至少一个时，线轴111和头壳112受到变化的阻力，给定电压和给定电流中的至少一个能够使控制器903输出使线轴111和头壳112中的至少一个克服变化的阻力中阻力值最大的阻力的控制信号。
如前所述，在本实施方式中，打草机100在自动绕线模式下，电机121驱动线轴111转动，线轴111相对头壳112转动时受到变化的阻力，线轴111相对头壳112转动时受到波动的阻力，而给定电压和给定电流中的至少一个的幅值或大小能够使控制器903输出使线轴111克服所述变化的阻力中最大阻力的控制信号。
在其他一些实施方式中，在自动绕线模式下，电机121驱动头壳112转动，头壳112相对线轴111相对转动时受到变化的阻力，给定电压和给定电流中的至少一个的幅值能够使控制器903输出使头壳111克服所述变化的阻力中最大阻力的控制信号。在其他的一些实施方式中，电机121驱动头壳112和线轴111转动，头壳112和线轴111转速存在速度差，从而使得头壳112和线轴111产生相对转动，头壳112和线轴111相对转动时受到变化的阻力，给定电压和给定电流中的至少一个的幅值能够使控制器903输出使线轴111和头壳112中的至少一个克服变化的阻力中最大阻力的控制信号。
控制器903根据给定电压和给定电流中的至少一个输出控制信号控制驱动电路902以在无刷电机901内产生旋转磁场，旋转的磁场能够驱动转子转动，转子与旋转磁场同步转动，这样，由转子驱动的线轴111和头壳112中的至少一个与旋转磁场同步转动，旋转磁场以基本恒定速度运行，从而使得电机121以基本恒定速度运行，进而线轴111和头壳112中的至少一个以基本恒定速度运行，这样打草绳101自动地缠绕至线轴111的速度也基本恒定，绕线速度更稳定。
作为一种实施方式，打草机100在自动绕线模式下，电机121驱动线轴111相对头壳112转动，控制器903根据给定电压输出控制信号以控制驱动电路902使无刷电机901以基本恒定速度运行，给定电压的幅值能够使控制器903输出使线轴111相对头壳112转动时能够克服变化的阻力中最大阻力的控制信号。
参照图11，作为一种实施方式，打草机100还包括PWM信号确定模块910，PWM信号确定模块910设置在控制器903中，PWM信号确定模块910用于根据给定电压计算和确定控制器903输出的能够使线轴111克服变化的阻力中最大阻力的PWM信号。也即是说，PWM信号确定模块910用于产生带动转子转动的目标旋转磁场的PWM信号，具体为PWM信号的脉冲宽度和切换点。
控制器903还包括PWM生成模块920，PWM生成模块920的输入端与PWM信号确定模块910的输出端连接，PWM生成模块920与驱动电路902连接。PWM生成模块920用于根据PWM信号确定模块910确定的PWM信号生成PWM信号以控制驱动电路902使导通的绕组产生目标旋转磁场，目标旋转磁场带动转子转动。
作为可选地，控制器903还包括功率驱动模块930，PWM生成模块920通过功率驱动模块930与驱动电路902连接，功率驱动模块930用于对PWM生成模块的PWM信号进行放大以能够驱动驱动电路902的开关元件导通。
在本实施方式中，PWM信号确定模块910包括：电压矢量给定单元911，用于给定PWM信号确定模块910需要合成的目标电压矢量；矢量时间作用单元912，其输入端与电压矢量给定单元911连接，其输出端与矢量切换点单元913连接，矢量时间作用单元912根据需要电压矢量给定单元911给定的目标电压矢量，确定合成目标电压矢量的基本电压矢量和零矢量的作用时间；矢量切换点单元913，其与矢量时间作用单元912连接，用于根据矢量时间作用单元912输出的基本电压矢量和零矢量的作用时间确定PWM信号需要切换的时间点，矢量切换点单元913包括定时器。
PWM生成模块920根据PWM信号确定模块91确定的能够产生带动转子转动的目标旋转磁场的PWM信号生成对应的PWM信号，PWM信号用于控制驱动电路902的开关元件，以导通相应绕组，产生与目标电压矢量对应的目标磁场。电压矢量给定单元911给定的目标电压矢量为一个沿逆时针或顺时针方向的旋转矢量，对应的目标磁场为一个沿逆时针或顺时针方向的旋转磁场。旋转磁场的转动方向与无刷电机901在自动绕线模式下的转动方向有关。
在本实施方式中，打草机100在切割模式下，如果无刷电机901正向转动，转子沿顺时针方向转动，那么在自动绕线模式下，无数电机901则反向转动，转子沿逆时针方向转动，则目标磁场为沿逆时针方向转动的旋转磁场。
电压矢量给定单元911给定的目标电压矢量的幅值足以克服上述线轴111相对头壳112转动时受到的最大阻力，绕组产生的旋转磁场可以带动转子以恒定的转速持续转动，从而使得线轴111的绕线速度稳定， 可以避免自动绕线模式下负载波动较大而损坏无刷电机901、线轴111和头壳112，以及造成绕线速度不稳定、绕线过程不顺畅的问题，不利于绕线。
在本实施方式中，线轴111的绕线速度与绕组产生的旋转磁场的旋转速度同步，二者转速相等或基本相等。电压矢量给定单元911给定的目标电压矢量的幅值与打草机100的供电电源的电源电压有关。
作为一种实施方式，给定电压与电源电压的比值的取值范围为：0.1～0.5。目标电压矢量的幅值与电源电压的幅值比值的取值范围为：0.1～0.5。在本实施方式中，电源采用电池包170。例如，以电池包170作为电源来说，目标电压矢量的幅值为电池包170的额定电压的10％～50％，例如，电池包170的额定电压为56V，目标电压矢量的幅值为可以为11V。在实际操作中，可以通过设定PWM信号的占空比来实现目标电压矢量的幅值。
下面对PWM信号确定模块910的原理进行详细说明。参照图12所示的电压空间矢量图，为了方便描述，引入扇区的概念，将整个平面分为六个扇区，每个扇区包含两个基本电压矢量u i，电压矢量给定单元911给定的目标电压矢量U s落在某个扇区，其由扇区边界的两个基本电压矢量u i进行合成，基本电压矢量u i为绕组的电压矢量，相邻的基本电压矢量u i间隔60°。
目标电压矢量给定单元911给定的目标电压矢量为U S为一个沿逆时针或顺时针方向的旋转矢量，其对应的目标磁场为一个沿逆时针或顺时针方向的旋转磁场。目标电压矢量U s的幅值通过反复试验获得，其值的选择应使得线轴111相对头壳112转动时能够克服最大阻力以能保持基本恒定的转速持续转动。
由于无刷电机901的绕组空间上呈互差120°分布，可以定义目标电压矢量为
Figure PCTCN2019129294-appb-000001
考虑到不同的变换，k可以取不同的值，如功率不变，电压电流幅值不变等。为了使合成的电压空间矢量在静止三相坐标轴上的投影和分矢量相等，将k值取为2/3，则目标电压矢量U S可以表示为：
Figure PCTCN2019129294-appb-000002
以图10的驱动电路902为例，第一桥臂902a、第二桥臂902b、第三桥臂902c这三个桥臂的六个开关元件共可以形成8种开关模式，用S A、S B、S c分别标记三个桥臂的状态，规定当每个桥臂的上桥臂开关元件(VT1、VT3、VT5)导通时桥臂状态为1，下桥臂开关元件(VT4、VT6、VT2)导通时桥臂状态为0，这样驱动电路902具有八种开关模式，在八种开关模式中，有六种开关模式对应非零电压空间矢量u 1～u 6，矢量的幅值为
Figure PCTCN2019129294-appb-000003
在空间上互差60°，U d为直流侧电压，对于电池包供电来说，U d为电池包的电压；有两种开关模式对应的电压矢量(u 0和u 7)的幅值为零，称为零矢量。当零矢量作用于电机时不形成磁链矢量；而当非零矢量作用于电机时，会在电机中形成相应的磁链矢量。
下面以开关状态(S A、S B、S C)＝(1、0、0)为例，即开关元件VT 1、VT 2、VT 6导通，其余关断。各相绕组的状态变为B相和C相并连后再和A相串连的形式，易得相电压：
Figure PCTCN2019129294-appb-000004
带入式
Figure PCTCN2019129294-appb-000005
可得目标电压矢量
Figure PCTCN2019129294-appb-000006
采用同样的方法可以获得不同开关状态S AS BS C对应的基本电压矢量u i及其表达式如下表1所示：
表1
Figure PCTCN2019129294-appb-000007
矢量作用时间单元912用于根据目标电压矢量给定单元911给定的目标电压矢量计算获得基本电压矢量和零矢量作用的时间。继续参照图12，假设目标电压矢量U S位于第III扇区为例，欲用基本电压矢量u 4、u 6、u 0及u 7合成，在两相静止参考坐标系(α，β)中，令U S和u 4间的夹角是θ，由伏秒平衡的原则和正弦定理，可得：
α轴：
Figure PCTCN2019129294-appb-000008
β轴：
Figure PCTCN2019129294-appb-000009
其中，T i为对应基本电压矢量u i作用的时间(i＝0～7)，T为采样周期，通常为PWM的调制周期，
Figure PCTCN2019129294-appb-000010
求解上面两式可以得到u 4,u 6这两个基本电压矢量u 4和u 6的作用时间可有下式计算获 得：
Figure PCTCN2019129294-appb-000011
其中，u α＝|U s|cosθ，u β＝|U s|sinθ，通过上面的方法即可以确定合成目标电压矢量U S的基本电压矢量u i的作用时间，当需要合成的目标电压矢量U S位于各个不同的扇区时都按照如上的运算。
通过对每个扇区基本电压矢量u i动作时间的求解不难发现它们都是一些基本时间的组合。所以定义几个基本的时间变量X、Y、Z。
Figure PCTCN2019129294-appb-000012
通过计算可以得到在每个扇区内的基本电压矢量u i的动作时间。设每个扇区的两个基本电压矢量u i动作的时间为T 1,T 2。于是可以得到基本电压矢量u i动作时间表如下表2所示，由此，矢量作用时间单元912基本电压矢量和零矢量作用的时间。
表2
Figure PCTCN2019129294-appb-000013
无刷电机901按照PWM信号确定模块910调制后的控制信号工作。其工作原理是：当驱动电路902按照PWM信号确定模块调制后的控制信号输出某一基本电压矢量u i时，形成磁链空间矢量ψ s，ψ s可表示为：
ψ s＝ψ s0+u i×Δt,
其中，ψ s0为初始磁链空间矢量；Δt为U i的作用时间。当u i为某一非零电压矢量(u 1～u 6)时，磁链空间矢量ψ s从初始位置出发，沿对应的目标电压矢量U S方向，以
Figure PCTCN2019129294-appb-000014
为半径进行旋转运动，当u i为一零电压矢量(u 0和u 7)时，ψ s＝ψ s0，磁链空间矢量的运动受到抑制。因此合理地选择六个非零矢量(u 1～u 6)的施加次序和作用时间，可使磁链空间矢量顺时针或逆时针旋转形成一定形状的磁链轨迹。在电机控制当中尽量使磁链轨迹逼近正多边形或圆形。同时，在两个非零矢量(u 0和u 7)之间按照一定的原则，比如开关次数最少，插入一个或多个零矢量并合理选择零矢量的作用时间，就能调节ψ s的运动速度，从而调节旋转磁场的速度，从而带动线轴111相对头壳112旋转进行绕线。如果在切割模式下，无刷电机901的转子是顺时针高速转动，则在自动绕线模式下，无刷电机901的转子是逆时针低速转动，通过调制出的PWM相应的控制磁链空间矢量ψ s沿逆时针方向转动。
在实际的操作中，也可以直接给出合成目标电压矢量U S的基本电压矢量u i，基本电压矢量u i能够合 成所需的目标电压矢量U S。给定的基本电压矢量u i可以通过对应的绕组在一个周期内的导通时间或占空比来表征。
在作为一种实施方式，在每个PWM调制周期内，开关状态S A、S B、S C有五种，且关于周期中心对称。需要在PWM周期的中间插入零矢量u 0和u 7，u 0和u 7具体采用哪一个根据旋转方向和开关动作次数最少的原则自行决定。例如在第Ⅲ扇区内，如果旋转方向为逆时针，则u 4先动作，u 6后动作以此类推，动作时间可以直接采用表2中的数据即可，然后选择零矢量即可使开关次数最少。
零矢量作用的时间可以表示为：T 0/T 7＝T-T 1-T 2。根据上述的配置原则，PWM生成模块920生成的在每个扇区内驱动电路902的开关元件动作的示意图如表4所示。
控制器903还包括矢量切换点单元913，矢量切换点单元913包括定时器，定时器设置成连续增/减计数模式，其用于对计算得出的基本电压矢量和零矢量作用的时间进行定时以确定矢量切换点，矢量切换点对应于PWM信号的切换点。
本申请还公开可以一种打草机100的控制方法，打草机100包括上述打草头110、驱动打草头110的无刷电机901、驱动无刷电机901运转的驱动电路902、控制驱动电路的控制器903；
打草机100的控制方法包括：在自动绕线模式下，根据给定电压和给定电流中的至少一个输出控制信号至驱动电路902使无刷电机901的转速基本恒定。
打草头110包括线轴111和头壳112，线轴111用于缠绕打草绳101，头壳112用于容纳线轴111.在自动绕线模式下，线轴111和头壳112受到变化的阻力；给定电压和给定电流中的至少一个能够使线轴111和头壳112中的至少一个克服变化的阻力中阻力值最大的阻力。
参照图13，打草机100的控制方法具体包括：
步骤S11：给定目标电压矢量。
在给定目标电压矢量之前，需要确定线轴111和头壳112中的至少一个在线轴111和头壳112发生相对转动时遇到的最大阻力，从而确定需要克服的最大阻力，该最大阻力可通过实验获得。在确定最大阻力之后即可确定给定目标电压矢量。该目标电压矢量U s与给定电压的幅值相等，且其能够使控制器903输出使线轴111和头壳112中的至少一个足以克服最大阻力的控制信号，从而使得在自动绕线模式下无刷电机901转速恒定、绕线速度稳定。给定目标电压矢量U s可预先存储在存储器中，电压矢量给定单元911作为存储器，其存储有给定目标电压矢量U s。
步骤S12：确定合成所述目标电压矢量的基本电压矢量和零矢量。
在确定目标电压矢量U s之后，即可确定目标电压矢量U s所处扇区位置，从而能够获得位于该扇区边界上的两个基本电压矢量u i。这样边能够获得合成所述目标电压矢量U s的基本电压矢量u i和零矢量。两个基本电压矢量u i和零矢量也可以直接预先存储在电压矢量给定单元911中，也可以是根据目标电压矢量u i通过比较和计算获得。假定合成的电压矢量落在第I扇区，可知其等价条件如下：
0°<arctan(u β/u α)<60°；
以上等价条件再结合图12的电压空间矢量图的几何关系分析，可以判断出合成的目标电压矢量U s落在第N扇区的充分必要条件，得出下表3：
表3
Figure PCTCN2019129294-appb-000015
Figure PCTCN2019129294-appb-000016
在确定扇区时，引入三个决策变量A，B，C。根据给出的待合成的目标电压矢量U s的两个分量u α和u β来决定A，B，C的取值，有以下关系式：
Figure PCTCN2019129294-appb-000017
所在扇区的位置N＝A+2B+4C，当N取不同的值对应的扇区位置如图12所示，这样给定一个目标电压矢量U s就可以确定其所在的扇区，从而就能够确定该扇区边界上的两个基本电压矢量u i和零矢量为合成目标电压矢量U s的两个基本电压矢量u i和零矢量。
步骤S13：确定所述基本电压矢量和零矢量的作用时间。
在确定基本电压矢量u i和零矢量之后，矢量作用时间单元912需要确定基本电压矢量u i和零矢量作用的时间，基本电压矢量u i和零矢量的作用时间可通过查询如上所述的表2以及通过变量X、Y、Z的公式计算获得，零矢量作用的时间可以表示为：T 0/T 7＝T-T 1-T 2。此处不再赘述。
步骤S14：确定所述基本电压矢量和零矢量的切换时间点；
在确定基本电压矢量u i和零矢量的作用时间后，矢量切换点单元913的定时器设置成连续增/减计数模式，其对计算得出的基本电压矢量u i和零矢量作用的时间进行定时以确定矢量切换点，矢量切换点对应于PWM信号的切换点。
根据所述基本电压矢量、所述零矢量以及所述基本电压矢量和所述零矢量的切换时间点即确定了需要生成的PWM信号。
步骤S15：生成PWM信号。
PWM信号生成模块920根据上述过程确定的PWM信号生成PWM信号输出给功率驱动模块930。作为一种实施方式，PWM信号生成模块920生成的PWM信号如下表4所示。
表4
Figure PCTCN2019129294-appb-000018
Figure PCTCN2019129294-appb-000019
表4中，PWMA表示发送至第一桥臂902a上的开关元件VT1和VT4的控制信号状态，当PWMA信号为1时，则上桥臂开关元件VT1导通，当PWMA信号为0时，则下桥臂开关元件VT4导通。同理，PWMB表示发送至第二桥臂902b上的开关元件VT3和VT6的控制信号的状态，当PWMB信号为1时，则上桥臂开关元件VT3导通，当PWMB信号为0时，则下桥臂开关元件VT6导通。PWMC表示发送至第三桥臂902c上的开关元件VT5和VT2的控制信号的状态，当PWMC信号为1时，则上桥臂开关元件VT5导通，当PWMC信号为0时，则下桥臂开关元件VT2导通。
以扇区Ⅰ为例，其所产生的三相波调制波形在采样时间T时段，基本电压矢量u i和零矢量出现的先后顺序为u 4、u 6、u 7、u 7、u 6、u 4，S A、S B、S c开关状态与三相波形则与表4中的第三列所示，各个开关元件的导通时间如三相波形下方所示。
步骤S16：以生成的PWM信号控制驱动电路使无刷电机以基本恒定的转速运行。
功率驱动模块930输出如表4所示的PWM信号至驱动电路902，驱动电路902按照控制器903输出的PWM信号动作，从而控制无刷电机901能够驱动线轴111和头壳112中的至少一个克服最大阻力转动，从而实现自动绕线模式下，电机转速恒定、绕线速度稳定，且能够实现电机稳定低速、大扭矩的控制效果，用户体验更好，有利于绕线作业，可以避免因线轴111相对头壳112低速反转时由于二者之间传动面的斜面设计造成线轴111所受阻力波动较大，从而导致的无刷电机901转速不稳定，绕线速度的不稳定，用户体验不佳等问题，且可以有效保护电机、线轴、头壳和打草绳。
在其他的实施方式中，至少在自动绕线模式下，控制器903根据给定电流输出控制信号以控制所述驱动电路902使所述电机901以基本恒定的转速运行，所述给定电流的幅值能够使控制器903输出使线轴111和头壳112中的至少一个克服变化的阻力中最大阻力的控制信号。

Claims (20)

  1. 一种打草机，包括：
    打草头；
    无刷电机，用于驱动所述打草头转动以切割植被；
    驱动电路，与所述电机连接，以驱动所述电机输出动力；
    控制器，与所述驱动电路连接，用于控制所述驱动电路；
    所述打草头包括线轴和头壳，所述线轴用于缠绕打草绳，所述头壳用于容纳所述线轴；
    所述打草机具有自动绕线模式，在所述自动绕线模式下，所述无刷电机驱动所述线轴和所述头壳中的至少一个以使所述线轴和所述头壳相对转动以将所述打草绳自动地缠绕至所述线轴；
    所述控制器被配置为：在所述自动绕线模式下，根据给定电压和给定电流中的至少一个输出控制信号至所述驱动电路使所述无刷电机的转速基本恒定。
  2. 根据权利要求1所述的打草机，其中，
    在所述自动绕线模式下，所述线轴和所述头壳受到变化的阻力；
    所述给定电压和所述给定电流中的至少一个能够使所述控制器输出使所述线轴和所述头壳中的至少一个克服所述变化的阻力中阻力值最大的阻力的控制信号。
  3. 根据权利要求1所述的打草机，其中，
    所述变化的阻力周期性波动。
  4. 根据权利要求2所述的打草机，其中，
    所述控制器包括：
    PWM信号确定模块，用于根据所述给定电压计算和确定所述控制器输出的能够使所述线轴和所述头壳中的至少一个克服所述变化的阻力中阻力值最大的阻力的PWM信号；
    PWM信号生成模块，用于根据所述PWM信号确定模块确定的所述PWM信号生成PWM信号以控制驱动电路。
  5. 根据权利要求4所述的打草机，其中，
    所述PWM信号确定模块包括：
    电压矢量给定单元，用于给定目标电压矢量，所述目标电压矢量的幅值与所述给定电压的幅值相等；
    矢量作用时间单元，用于根据所述电压矢量给定单元给定的所述目标电压矢量确定合成所述目标电压矢量的基本电压矢量和零矢量的作用时间，所述矢量作用时间单元的输入端与所述电压矢量给定单元的输出端连接；
    矢量切换点单元，用于确定所述基本电压矢量和零矢量的切换时间点，所述矢量切换点单元的输入端与所述矢量作用时间单元的输出端连接。
  6. 根据权利要求1所述的打草机，其中，
    所述控制器被配置为：
    在所述自动绕线模式下，根据所述给定电压和给定电流中的至少一个输出控制信号至所述驱动电路以在所述无刷电机内产生旋转磁场，所述线轴和所述头壳中的至少一个与所述旋转磁场基本同步转动。
  7. 根据权利要求1所述的打草机，其中，
    所述头壳和所述线轴中的至少一个绕中心轴线转动，所述中心轴线与驱动轴的轴线基本重合，所述驱动轴由所述无刷电机驱动从而驱动所述打草头；
    所述线轴形成有第一斜面，所述头壳形成有第二斜面，所述第一斜面和所述第二斜面倾斜于所述中心轴线的法平面；
    在所述自动绕线模式下，所述第一斜面和所述第二斜面相互接触并相对滑动以使得所述线轴和所述头壳能够相对转动。
  8. 根据权利要求7所述的打草机，其中，
    所述线轴形成有绕所述中心轴线周向排布的多个第一啮合齿，所述第一啮合齿形成有所述第一斜面；
    所述头壳形成有与所述多个第一啮合齿配合的多个第一配合齿，所述第一配合齿形成有所述第二斜面。
  9. 根据权利要求8所述的打草机，其中，
    所述多个第一啮合齿中相邻的两个第一啮合齿在所述中心轴线的周向上相互间隔第二尺寸。
  10. 根据权利要求8所述的打草机，其中，
    所述打草机还具有切割模式；
    在所述切割模式下，所述第一啮合齿与所述第一配合齿相互止挡；
    在所述自动绕线模式下，所述第一啮合齿与所述第一配合齿相互接触并相对滑动。
  11. 根据权利要求8所述的打草机，其中，
    所述多个第一啮合齿中的每个第一啮合齿形成的所述第一斜面沿所述中心轴线的周向方向倾斜；
    所述多个第一配合齿中的每个第一配合齿形成的所述第二斜面沿所述中心轴线的周向方向倾斜。
  12. 根据权利要求1所述的打草机，其中，
    所述打草机还具有切割模式，在所述切割模式下，所述线轴和所述头壳同步转动；
    所述控制器被配置为：
    在所述切割模式下，以第一控制模式控制所述驱动电路使所述无刷电机以第一转速运行；
    在所述自动绕线模式下，以第二控制模式控制所述驱动电路使所述无刷电机以第二转速运行；
    所述第二转速小于所述第一转速。
  13. 根据权利要求12所述的打草机，其中，
    所述第一转速与所述第二转速的比值的取值范围为：10～100。
  14. 根据权利要求12所述的打草机，其中，
    所述控制器被配置为：
    在所述切割模式时，使所述无刷电机以所述第一转速沿第一方向转动；
    在所述自动绕线模式时，使所述无刷电机以所述第二转速沿第二方向转动；
    所述第一方向与所述第二方向相反。
  15. 根据权利要求1所述的打草机，其中，
    所述打草机由供电电源提供电能，所述给定电压与所述供电电源的电压的比值的取值范围为：0.1～0.5。
  16. 一种打草机的控制方法，所述打草机具有自动绕线模式，所述打草机包括打草头、驱动所述打草头的无刷电机、驱动所述无刷电机运转的驱动电路、控制所述驱动电路的控制器；
    所述打草机的控制方法包括：
    在所述自动绕线模式下，根据给定电压和给定电流中的至少一个输出控制信号至所述驱动电路使所述无刷电机的转速基本恒定。
  17. 根据权利要求16所述的打草机的控制方法，其中，
    所述打草头包括线轴和头壳，所述线轴用于缠绕打草绳，所述头壳用于容纳所述线轴；
    在所述自动绕线模式下，所述线轴和所述头壳受到变化的阻力；
    所述给定电压和所述给定电流中的至少一个能够使所述线轴和所述头壳中的至少一个克服所述变化的阻力中阻力值最大的阻力。
  18. 根据权利要求16所述的打草机的控制方法，其中，
    所述打草机的控制方法包括：
    给定目标电压矢量，所述目标电压矢量的幅值与所述给定电压的幅值相等；
    确定合成所述目标电压矢量的基本电压矢量和零矢量；
    确定所述基本电压矢量和零矢量的作用时间；
    确定所述基本电压矢量和零矢量的切换时间点；
    根据所述基本电压矢量、所述零矢量以及所述基本电压矢量和所述零矢量的切换时间点确定PWM信号。
  19. 根据权利要求16所述的打草机的控制方法，其中，
    所述头壳和所述线轴中的至少一个绕中心轴线转动，所述中心轴线与驱动轴的轴线基本重合，所述驱 动轴由所述无刷电机驱动从而驱动所述打草头；
    所述线轴形成有第一斜面，所述头壳形成有第二斜面，所述第一斜面和所述第二斜面倾斜于所述中心轴线的法平面；
    在所述自动绕线模式下，所述第一斜面和所述第二斜面相互接触并相对滑动以使得所述线轴和所述头壳能够相对转动。
  20. 根据权利要求16所述的打草机的控制方法，其中，
    所述打草机还具有切割模式，在所述切割模式下，所述线轴和所述头壳同步转动；所述控制器被配置为：
    在所述切割模式下，以第一控制模式控制所述驱动电路使所述无刷电机以第一转速沿第一方向转动；
    在所述自动绕线模式下，以第二控制模式控制所述驱动电路使所述无刷电机以第二转速沿第二方向转动运行；
    所述第二转速小于所述第一转速，所述第二方向与所述第一方向相反。
PCT/CN2019/129294 2018-12-28 2019-12-27 打草机以及打草机的控制方法 WO2020135750A1 (zh)

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