Manned lawn mower and control method therefor

Abstract

A manned lawn mower (100), comprising: a motor (20); an output member; a power supply device; a drive circuit (40), comprising a plurality of switch elements that are electrically connected between the power supply device and the motor; and a controller (50), at least electrically connected to the drive circuit, the controller being used for outputting a drive signal to the drive circuit so as to enable the motor to be operated, and the drive signal at least comprising a switching frequency. The controller is configured to control the switching frequency of the drive signal to be a first switching frequency f1 when the rotation speed of the motor is within a first rotation speed range, and control the switching frequency of the drive signal to be a second switching frequency when the rotation speed of the motor is within a second rotation speed range, the first switching frequency having a first positive correlation with the rotation speed of the motor, and the second switching frequency having a second positive correlation with the rotation speed of the motor. The present invention also relates to a control method for the manned lawn mower.

Description

Manned lawnmower and its control method

[0001] This application claims priority to Chinese patent applications filed on October 29, 2024, with application number 202411528657.5; filed on September 15, 2025, with application number 202511316435.1; and filed on September 15, 2025, with application number 202511316972.6, the entire contents of which are incorporated herein by reference. Technical Field

[0002] This application relates to the field of tool and equipment technology, specifically to a manned lawnmower and its control method. Background Technology

[0003] With the development of electronic technology, power tools are being used more and more widely, and users are demanding higher and higher control precision and energy efficiency from them.

[0004] One type of manned lawnmower in related technology uses a fixed switching frequency to control the motor operation. However, using a fixed switching frequency to control the motor makes it difficult to balance control accuracy and switching losses in the drive circuit. For example, a higher switching frequency ensures control accuracy when the motor is running at high speeds, but results in greater switching losses at low speeds. Conversely, a lower switching frequency results in lower switching losses at low speeds, but lower control accuracy at high speeds. Furthermore, when the motor is stalled, overloaded, or overheated, using the same switching frequency as during normal operation will generate even more losses, causing the controller to overheat rapidly and potentially burn out.

[0005] This section provides background information related to this application, which is not necessarily prior art. Summary of the Invention

[0006] One objective of this application is to solve or at least mitigate some or all of the aforementioned problems. Therefore, one objective of this application is to provide a manned lawnmower and its control method to address the problems existing in the prior art, achieve synchronous modulation of the manned lawnmower, and enable the manned lawnmower to balance control accuracy and switching losses of the drive circuit during operation, thereby greatly improving the operational stability of the manned lawnmower while reducing switching losses.

[0007] To achieve the above objectives, this application adopts the following technical solution: a manned lawnmower, comprising: a motor; the motor operating at least in a first speed range and a second speed range; an output component; the motor driving the output component to perform the functions of a manned lawnmower; a power supply device for supplying power to the motor; a drive circuit including a plurality of switching elements electrically connected to the power supply device and the motor; a controller for at least being electrically connected to the drive circuit; the controller outputting a drive signal to the drive circuit to cause the motor to operate; the drive signal including at least a switching frequency; the controller being configured to: when the motor speed is in the first speed range, control the switching frequency of the drive signal to be a first switching frequency f1, and when the motor speed is in the second speed range, control the switching frequency of the drive signal to be a second switching frequency; wherein the first switching frequency is positively correlated with the motor speed, and the second switching frequency is positively correlated with the motor speed.

[0008] In some embodiments, the maximum speed in the first speed range is less than or equal to the minimum speed in the second speed range; the first switching frequency f1 = M1*P*n / 60, the second switching frequency f2 = M2*P*n / 60, where P is the number of pole pairs of the motor, n is the speed of the motor, M1 is the number of control cycles of the motor within the electrical angle period in the first speed range, M2 is the number of control cycles of the motor within the electrical angle period in the second speed range, and M1 is greater than M2.

[0009] In some embodiments, the motor also operates in a third speed range; the maximum speed in the third speed range is less than or equal to the minimum speed in the first speed range and the second speed range; the controller is also configured to: when the motor speed is in the third speed range, the switching frequency of the control drive signal is a third switching frequency f3; the third switching frequency f3 is less than the first switching frequency f1 and the second switching frequency f2.

[0010] In some embodiments, the controller is further configured to: determine the switching frequency adjustment coefficient k based on preset conditions, and update the first switching frequency f1 and the second switching frequency f2 based on the switching frequency adjustment coefficient k.

[0011] In some embodiments, the controller is further configured to: determine the switching frequency adjustment coefficient k based on preset conditions, and update the first switching frequency f1, the second switching frequency f2, and the third switching frequency f3 based on the switching frequency adjustment coefficient k.

[0012] In some embodiments, when the motor is stationary or stalled, the switching frequency of the drive signal is the stationary switching frequency f0; where f0 < f3; the value range of the switching frequency adjustment coefficient k is determined according to the first formula; where the first formula is as follows: f0 / f3 < k < f1max / f2max; where fmax is the highest switching frequency theoretically allowed by the drive circuit; f2max is the highest switching frequency actually allowed by the drive circuit.

[0013] In some embodiments, the preset conditions include at least one of the torque of the motor, the current of the motor, the bus voltage of the motor, and the temperature of the controller.

[0014] In some embodiments, the motor includes a traveling motor; the output member includes a traveling wheel; the traveling motor is used to drive the traveling wheel to rotate.

[0015] In some embodiments, the motor includes a mowing motor; the output member includes a mowing mechanism; the mowing motor is used to drive the mowing mechanism to rotate.

[0016] In some embodiments, the maximum output power of the motor is less than or equal to 50 kW.

[0017] In some embodiments, the power supply device includes at least one battery pack; the battery pack is detachably mounted to the ride-on mower.

[0018] An embodiment of the present application discloses a ride-on mower, including: a motor; the motor operates at least in a first speed range and a second speed range; an output member; the motor drives the output member to perform the functions of the ride-on mower; a power supply device, at least used to supply power to the motor; a drive circuit, including a plurality of switching elements electrically connected between the power supply device and the motor; a controller, at least electrically connected to the drive circuit; the controller is used to output a drive signal to the drive circuit to make the motor operate; the drive signal at least includes a switching frequency; the controller is configured to: at least based on the speed of the motor, determine the switching frequency of the drive signal to control the operation of the motor; where the switching frequency increases with the increase of the speed of the motor within each speed range; or, the switching frequency increases with the increase of the speed of the motor between each speed range.

[0019] One embodiment of this application discloses a manned lawnmower, comprising: a motor; an output component, the motor driving the output component to perform the functions of a manned lawnmower; a power supply device for supplying power to the motor; a drive circuit including a plurality of switching elements electrically connected to the power supply device and the motor; a controller for at least being electrically connected to the drive circuit; the controller for outputting a drive signal to the drive circuit to cause the motor to operate; the drive signal including at least a switching frequency; the controller being configured to: determine the switching frequency of the drive circuit based on a first parameter of the motor, and update the switching frequency based on a second parameter; wherein the first parameter includes the motor speed; the second parameter includes at least one of the motor torque, the motor current, the motor bus voltage, and the controller temperature; the switching frequency increases with the increase of the motor speed within each speed range; or, the switching frequency increases with the increase of the motor speed between each speed range.

[0020] In some embodiments, when the second parameter includes the motor torque or current, the controller is configured to reduce the switching frequency when the torque is less than a torque threshold or the current is less than a current threshold.

[0021] In some embodiments, when the second parameter includes the bus voltage, the controller is configured to reduce the switching frequency when the bus voltage is less than a voltage threshold.

[0022] In some embodiments, when the second parameter includes the controller temperature, the controller is configured to: increase the switching frequency when the controller temperature is less than a first temperature threshold, and decrease the switching frequency when the controller temperature is greater than a second temperature threshold; wherein the first temperature threshold is less than the second temperature threshold.

[0023] In some embodiments, when the second parameter includes at least two of the motor torque, motor current, voltage bus, and controller temperature, the controller is configured to: update the switching frequency according to the motor torque, motor current, voltage bus, and controller temperature respectively, and control the motor to operate according to the smallest of the updated switching frequencies as the updated switching frequency.

[0024] In some embodiments, when the motor speed is less than a speed threshold, the controller is configured to set the switching frequency to a preset value.

[0025] In some embodiments, the motor includes a walking motor; the output component includes a walking wheel; the walking motor is used to drive the walking wheel to rotate.

[0026] In some embodiments, the motor includes a mowing motor; the output includes a mowing mechanism; the mowing motor is used to drive the mowing mechanism to rotate.

[0027] In some embodiments, the maximum output power of the motor is less than or equal to 50kW.

[0028] In some embodiments, the bus voltage is less than or equal to 250V.

[0029] In some embodiments, the power supply includes at least one battery pack; the battery pack is detachably mounted to the manned lawnmower.

[0030] One embodiment of this application discloses a control method for a manned lawnmower, wherein the manned lawnmower includes: a motor; the motor operates at least in a first speed range and a second speed range; an output component; the motor drives the output component to perform the functions of the manned lawnmower; a power supply device for supplying power to the motor; a drive circuit including a plurality of switching elements electrically connected to the power supply device and the motor; a controller for at least being electrically connected to the drive circuit; the controller outputting a drive signal to the drive circuit to cause the motor to run; the drive signal including at least a switching frequency; and a control method including: setting the switching frequency of the drive circuit using a first parameter and a preset switching frequency curve; updating the switching frequency using a second parameter; and outputting a drive signal based on the updated switching frequency to control the motor operation; wherein the first parameter and the second parameter respectively include at least one of the motor speed, the motor torque, the motor current, the bus voltage, and the controller temperature; the switching frequency increases with the increase of the motor speed within each speed range; or, the switching frequency increases with the increase of the motor speed between each speed range.

[0031] One embodiment of this application discloses a manned lawnmower, comprising: a motor; an output component, the motor driving the output component to perform the functions of a manned lawnmower; a power supply device for supplying power to the motor; a drive circuit including a plurality of switching elements electrically connected to the power supply device and the motor; a controller for at least being electrically connected to the drive circuit; the controller being configured to output a drive signal to the drive circuit to cause the motor to run; the drive signal including at least a switching frequency; the controller being configured to: control the switching frequency of the drive signal to switch from a first switching frequency to a second switching frequency based on relevant parameters to reduce the switching losses of the drive circuit.

[0032] In some embodiments, the relevant parameters include at least one of the following: motor speed, motor torque, motor current, bus voltage, and controller temperature. Attached Figure Description

[0033] Figure 1 is a physical diagram of a manned lawnmower provided in an embodiment of this application;

[0034] Figure 2 is a schematic diagram of the circuit structure of a manned lawnmower provided in an embodiment of this application;

[0035] Figure 3 is a schematic diagram showing the relationship between the motor speed and switching frequency in a manned lawnmower provided in an embodiment of this application;

[0036] Figure 4 is a schematic diagram showing the relationship between the motor speed and the switching frequency in another manned lawnmower provided in an embodiment of this application;

[0037] Figure 5 is a schematic diagram showing the relationship between the motor speed and switching frequency in another manned lawnmower provided in the embodiments of this application;

[0038] Figure 6 is a schematic diagram showing the relationship between the motor speed and the switching frequency in another manned lawnmower provided in the embodiments of this application;

[0039] Figure 7 is a flowchart of a control method for a manned lawnmower provided in an embodiment of this application. Detailed Implementation

[0040] Before explaining any implementation of this application in detail, it should be understood that this application is not limited to its application to the structural details and component arrangements set forth in the following description or shown in the above drawings.

[0041] In this application, the terms "comprising," "including," "having," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes that element.

[0042] In this application, the term "and / or" describes the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent three cases: A existing alone, A and B existing simultaneously, and B existing alone. Additionally, the character " / " in this application generally indicates that the preceding and following related objects have an "and / or" relationship.

[0043] In this application, the terms "connection," "combination," "coupling," and "installation" can refer to direct connection, combination, coupling, or installation, or indirect connection, combination, coupling, or installation. For example, a direct connection refers to two parts or components being connected together without the need for an intermediary, while an indirect connection refers to two parts or components each being connected to at least one intermediary, with the connection achieved through the intermediary. Furthermore, "connection" and "coupling" are not limited to physical or mechanical connections or couplings, but can also include electrical connections or couplings.

[0044] In this application, those skilled in the art will understand that relative terms (e.g., “about,” “approximately,” “basically,” etc.) used in conjunction with quantities or conditions are to include the values ​​and have the meaning indicated by the context. For example, such relative terms include at least the degree of error associated with the measurement of a particular value, tolerances associated with the particular value due to manufacturing, assembly, use, etc. Such terms should also be considered as disclosing a range defined by the absolute values ​​of the two endpoints. Relative terms may refer to a certain percentage (e.g., 1%, 5%, 10% or more) of the indicated value. Numerical values ​​not using relative terms should also be disclosed as specific values ​​with tolerances. Furthermore, “basically” when expressing relative angular relationships (e.g., substantially parallel, substantially perpendicular) may refer to a certain degree (e.g., 1 degree, 5 degrees, 10 degrees or more) added to or subtracted from the indicated angle.

[0045] In this application, those skilled in the art will understand that the function performed by a component can be performed by one component, multiple components, one part, or multiple parts. Similarly, the function performed by a part can also be performed by one part, one component, or a combination of multiple parts.

[0046] In this application, the directional terms "upper," "lower," "left," "right," "front," and "rear" are used to describe the orientation and positional relationships shown in the accompanying drawings and should not be construed as limiting the embodiments of this application. Furthermore, in the context, it should be understood that when an element is mentioned as being connected "upper" or "lower" to another element, it can be directly connected to the other element "upper" or "lower," or indirectly connected through an intermediate element. It should also be understood that directional terms such as upper side, lower side, left side, right side, front side, and rear side not only represent positive orientation but can also be understood as lateral orientation. For example, "below" can include directly below, lower left, lower right, lower front, and lower rear.

[0047] In this application, the terms "controller," "processor," "central processing unit," "CPU," and "MCU" are used interchangeably. When using the unit "controller," "processor," "central processing unit," "CPU," or "MCU" to perform a specific function, unless otherwise stated, these functions may be performed by a single or multiple of the aforementioned units.

[0048] In this application, the terms "device," "module," or "unit" are used to describe devices that can be implemented in hardware or software to perform a specific function.

[0049] In this application, the terms “calculation,” “judgment,” “control,” “determine,” “identify,” etc., refer to the operation and process of a computer system or similar electronic computing device (e.g., controller, processor, etc.).

[0050] It should be noted that the power tools provided in this application's embodiments may include, but are not limited to, outdoor walking devices such as electric handcarts, and manned work vehicles such as manned lawnmowers. Any technical solution that adopts the substantive content disclosed below will fall within the protection scope of this application.

[0051] Figure 1 is a physical diagram of a manned lawnmower provided in an embodiment of this application. Referring to Figure 1, the manned lawnmower 100 provided in this embodiment includes: a housing assembly 1, a power supply (not shown in the figure), a mowing mechanism 3, wheels 4, an operating assembly 5, a frame 11, and a support unit. The frame 11 extends in a front-to-back direction and, together with the housing assembly 1, constitutes the main unit of the manned lawnmower 100. The main unit is used to mount the power supply, mowing mechanism 3, wheels 4, and support unit. The wheels 4 support the main unit. The operating assembly 5 includes a joystick assembly for operating and controlling the manned lawnmower to move forward, backward, and turn. In some embodiments, the operating assembly 5 also includes a steering wheel assembly. The support unit is mounted on the frame 11 and supports the operator. Optionally, the support unit includes a seat 91. The seat 91 is mounted to the frame 11 for the user to sit on. Optionally, the support unit also includes a platform for the user to stand on. The power supply provides energy to the mowing mechanism 3 and the wheels 4. In one alternative embodiment, the power supply includes at least one battery pack detachably mounted to the manned lawnmower, allowing for convenient and timely removal of the battery pack when replacement is needed. Compared to fuel-powered manned lawnmowers, electric manned lawnmowers are more energy-efficient and environmentally friendly. In some embodiments, the manned lawnmower 100 further includes a grass collection device for collecting grass clippings cut by the mowing mechanism 3. Exemplarily, the grass collection device includes a grass basket assembly detachably mounted behind the seat 91.

[0052] Both the mowing mechanism 3 and the wheels 4 are output components of the manned lawnmower. The manned lawnmower 100 also includes a motor 20, a drive circuit 40, and a controller 50. In one optional embodiment, the motor 20 includes a travel motor for driving the wheels to rotate. In another optional embodiment, the motor 20 includes a mowing motor for driving the mowing mechanism to rotate.

[0053] Motor 20 drives the output components during operation to perform the functions of a manned lawnmower. Motor 20 includes a rotor and three-phase stator windings. Optionally, the motor can be a three-phase brushless motor, with its three-phase stator windings A, B, and C connected in a delta or Y configuration. In an optional embodiment, the maximum output power of the motor is less than or equal to 50 kW. The drive circuit includes multiple switching elements electrically connected between the power supply unit 30 and the motor. Controller 50 is at least electrically connected to the drive circuit and outputs drive signals to the drive circuit to operate the motor. In an optional embodiment, the drive signal includes at least a switching frequency.

[0054] Figure 2 is a schematic diagram of the circuit structure of a manned lawnmower provided in an embodiment of this application. Referring to Figures 1 and 2, in an optional embodiment, the drive circuit 40 is electrically connected between the power supply device and the three-phase stator windings A, B, and C of the motor to control the speed of the drive motor 20. The drive circuit 40 includes a plurality of switching elements Q1, Q2, Q3, Q4, Q5, and Q6. Each gate terminal of the switching element is electrically connected to the controller 50 to receive a drive signal from the controller 50. Each drain or source terminal of the switching element is connected to the three-phase stator windings A, B, and C of the motor 20. The switching elements Q1-Q6 receive the drive signal from the controller 50 and change their respective conduction states, thereby changing the phase current on each phase of the three-phase stator windings A, B, and C of the drive motor 20, thereby controlling the speed of the motor. In an exemplary embodiment, the drive circuit 40 may be a three-phase bridge driver circuit including six controllable semiconductor power devices (e.g., FETs, BJTs, IGBTs, etc.). It is understood that the aforementioned switching element can also be any other type of solid-state switch, such as an insulated gate bipolar transistor (IGBT), a bipolar junction transistor (BJT), etc.

[0055] Optionally, the controller 50 is configured to: control the switching frequency of the drive signal to be a first switching frequency f1 when the motor speed is in the first speed range, and control the switching frequency of the drive signal to be a second switching frequency when the motor speed is in the second speed range.

[0056] The first switching frequency is positively correlated with the motor speed, and the second switching frequency is positively correlated with the motor speed.

[0057] The motor operates at least in a first speed range and a second speed range. The speeds included in the first speed range are different from those included in the second speed range. In an optional embodiment, the maximum speed in the first speed range is less than or equal to the minimum speed in the second speed range. For example, both the first and second speed ranges are medium-to-high speed ranges, with the first speed range being [1800 rpm / min, 3200 rpm / min] and the second speed range being [3200 rpm / min, 4500 rpm / min]. In an optional embodiment, the motor also operates in a fourth speed range. The minimum speed in the fourth speed range is greater than or equal to the maximum speed in the second speed range.

[0058] The first positive correlation and the second positive correlation can be the same or different, and this embodiment does not specifically limit this. In an optional embodiment, the first positive correlation and the second positive correlation are different, the first switching frequency f1 = M1*P*n / 60, and the second switching frequency f2 = M2*P*n / 60.

[0059] Where P is the number of pole pairs of the motor, n is the speed of the motor, M1 is the number of control operations within the electrical angle period of the motor in the first speed range, and M2 is the number of control operations within the electrical angle period of the motor in the second speed range, with M1 being greater than M2.

[0060] In this embodiment, the drive circuit is electrically connected to both the controller and the motor. The controller outputs a drive signal to the drive circuit. The drive signal includes the switching frequency of the switching elements, and the drive circuit drives the motor to operate according to the drive signal. The controller is configured to control the switching frequency of the drive signal to a first switching frequency f1 when the motor speed is in a first speed range, and to control the switching frequency of the drive signal to a second switching frequency when the motor speed is in a second speed range. The first switching frequency f1 has a first positive correlation with the motor speed, and the second switching frequency f2 has a second positive correlation with the motor speed. This allows the manned lawnmower to balance control accuracy and switching losses of the drive circuit during operation. Furthermore, the switching frequency of the drive signal is segmented and synchronously modulated according to the speed change to ensure that the controller can output a symmetrical waveform, making the controller's modulation of the drive signal more stable, thereby making the operation of the manned lawnmower more stable.

[0061] Optionally, the motor also operates in the third speed range. The maximum speed in the third speed range is less than or equal to the minimum speed in the first and second speed ranges. The controller is also configured such that when the motor speed is in the third speed range, the switching frequency of the control drive signal is the third switching frequency f3.

[0062] The third switching frequency f3 is less than the first switching frequency f1 and the second switching frequency f2. In an optional embodiment, the third switching frequency f3 is 10000Hz.

[0063] In one optional embodiment, the third speed range is a low-to-medium speed range, specifically [200 rpm / min, 1800 rpm / min]. Since the maximum speed in the third speed range is less than or equal to the minimum speed in the first and second speed ranges, by making the third switching frequency f3 less than the first switching frequency f1 and the second switching frequency f2, the manned lawnmower uses a lower switching frequency at lower motor speeds, reducing switching losses and thus achieving higher control efficiency. Simultaneously, by appropriately increasing the control frequency at higher motor speeds, control accuracy is ensured, harmonic current is reduced, thereby improving the control performance of the manned lawnmower.

[0064] In one alternative embodiment, when the motor is stationary or stalled, the switching frequency of the drive signal is the stationary switching frequency f0.

[0065] Where f0 < f3. In an optional embodiment, the motor is considered stationary when its speed is less than or equal to 200 rpm / min. Motor stall can be understood as the situation where the motor is still outputting torque even when its speed is 0. In an optional embodiment, whether the motor is stalled can be determined based on at least one of the following parameters: motor speed, current, and temperature. This embodiment does not specifically limit the method for determining whether the motor is stalled.

[0066] The stationary switching frequency f0 is less than the third switching frequency f3. In an optional embodiment, the stationary switching frequency f0 is 5000 Hz.

[0067] Figure 3 is a schematic diagram illustrating the relationship between the motor speed and switching frequency in a manned lawnmower according to an embodiment of this application. In an exemplary embodiment, referring to Figure 3, when the motor speed is less than 200 rpm, it is considered that the motor is stationary or stalled, and the switching frequency of the drive signal is set to 5000 Hz. When the motor speed is in the third speed range, i.e., the motor speed is greater than 200 rpm and less than 1800 rpm, it is considered that the motor speed is in the low-to-medium speed range, and the switching frequency of the drive signal is set to 10000 Hz. When the motor speed is in the first speed range, i.e., the motor speed is greater than 1800 rpm and less than 3200 rpm, the switching frequency of the drive signal is positively correlated with the motor speed. When the motor speed is in the second speed range, i.e., the motor speed is greater than 3200 rpm and less than 4500 rpm, the switching frequency of the drive signal is positively correlated with the motor speed. When the motor speed is in the fourth speed range, i.e., the motor speed is greater than 4500 rpm, the switching frequency of the drive signal is positively correlated with the motor speed.

[0068] Optionally, the controller is also configured to: determine the switching frequency adjustment coefficient k based on preset conditions, and update the first switching frequency f1 and the second switching frequency f2 based on the switching frequency adjustment coefficient k.

[0069] The preset conditions can be the operating status of the manned lawnmower. In an optional embodiment, the preset conditions may include, but are not limited to, at least one of the following: motor torque, motor current, motor bus voltage, and controller temperature.

[0070] The preset conditions include at least one of the following: motor torque, motor current, motor bus voltage, and controller temperature. This can be understood as the preset conditions including one or more of the following: motor torque, motor current, motor bus voltage, and controller temperature. The bus voltage is less than or equal to 250V.

[0071] In some embodiments, when the preset conditions include one of the motor torque, motor current, motor bus voltage, and controller temperature, the switching frequency adjustment coefficient k is determined based on the parameters in the preset conditions.

[0072] In some embodiments, when the preset conditions include multiple of the following, such as the motor torque, the motor current, the motor bus voltage, and the controller temperature, two switching frequency adjustment coefficients k are determined based on the parameters in the preset conditions, and the first switching frequency f1 and the second switching frequency f2 are updated based on the smaller of the two switching frequency adjustment coefficients k.

[0073] The switching frequency adjustment factor k can be understood as a coefficient determined according to preset conditions for updating the first switching frequency f1 and the second switching frequency f2. For example, the updated first switching frequency f1' = kf1, and the updated second switching frequency f2' = kf2.

[0074] In an optional embodiment, the controller is further configured to: determine a switching frequency adjustment coefficient k based on preset conditions, and update a third switching frequency f3 based on the switching frequency adjustment coefficient k. For example, the updated third switching frequency f3' = kf3.

[0075] In an optional embodiment, the range of values ​​for the switching frequency adjustment coefficient k is determined according to the first formula.

[0076] The first formula is as follows: f0 / f3 <k<f1max / f2max。

[0077] Where fmax is the theoretically allowed highest switching frequency of the drive circuit; and f2max is the actual allowed highest switching frequency of the drive circuit.

[0078] In an optional embodiment, f0 / f3 = 5000Hz / 10000Hz = 0.5, fmax / f2max = 20000Hz / 18000Hz = 1.11, that is, 0.5 < k < 1.11.

[0079] Figure 4 is a schematic diagram illustrating the relationship between the motor speed and switching frequency in another manned lawnmower provided in an embodiment of this application. In an exemplary embodiment, referring to Figure 4, the orange solid line represents the relationship curve between the motor speed and switching frequency when the switching frequency adjustment coefficient is 1; the blue dashed line represents the relationship curve between the motor speed and switching frequency when the switching frequency adjustment coefficient is 0.8; and the gray dashed line represents the relationship curve between the motor speed and switching frequency when the switching frequency adjustment coefficient is 1.1. When the motor speed is less than 200 rpm, it is considered that the motor is stationary or stalled, and at this time, the switching frequency of the drive signal is not updated.

[0080] When the motor speed is in the first speed range, the second speed range, the third speed range, and the fourth speed range, that is, when the motor speed is in the low-to-medium speed stage and the medium-to-high speed stage, the switching frequency of the drive signal is updated based on the switching frequency adjustment coefficient k.

[0081] In one alternative embodiment, the controller is configured to determine the switching frequency of the drive signal, based at least on the motor's rotational speed, to control the motor's operation.

[0082] Specifically, the switching frequency increases with the increase of motor speed within each speed range; or, the switching frequency increases with the increase of motor speed between each speed range.

[0083] The increase in switching frequency with increasing motor speed across different speed ranges can be understood as the increase in the switching frequency of the drive signal with increasing motor speed within the same speed range. In an exemplary embodiment, when the motor speed is in the first speed range, the switching frequency of the drive signal is positively correlated with the motor speed. When the motor speed is in the second speed range, the switching frequency of the drive signal is also positively correlated with the motor speed.

[0084] The increase in switching frequency with increasing motor speed across different speed ranges can be understood as the increase in the switching frequency of the drive signal as the motor speed increases within each speed range. Figure 5 is a schematic diagram illustrating the relationship between motor speed and switching frequency in another type of manned lawnmower provided in this application embodiment. In an exemplary embodiment, referring to Figure 5, when the motor speed is less than 200 rpm, it is considered that the motor is stationary or stalled, and at this time, the switching frequency of the drive signal is set to 5000 Hz. When the motor speed is in the third speed range, i.e., the motor speed is greater than 200 rpm and less than 2000 rpm, the switching frequency of the drive signal is set to 10000 Hz. When the motor speed is in the first speed range, i.e., the motor speed is greater than 2000 rpm and less than 4000 rpm, the switching frequency of the drive signal is set to 14000 Hz. When the motor speed is in the second speed range, i.e., the motor speed is greater than 4000 rpm, the switching frequency of the drive signal is set to 18000 Hz.

[0085] Figure 6 is a schematic diagram illustrating the relationship between the motor speed and switching frequency in another type of manned lawnmower provided in this application embodiment. In an optional embodiment, referring to Figure 6, the switching frequency increases with the increase of the motor speed in some speed ranges, and also increases with the increase of the motor speed in some speed ranges. Specifically, when the motor speed is less than 200 rpm, the switching frequency of the drive signal is set to 5000 Hz. When the motor speed is in the third speed range, i.e., the motor speed is greater than 200 rpm and less than 2000 rpm, the switching frequency of the drive signal is set to 10000 Hz. When the motor speed is in the first speed range, i.e., the motor speed is greater than 2000 rpm and less than 3600 rpm, the switching frequency of the drive signal is positively correlated with the motor speed. When the motor speed is in the second speed range, i.e., the motor speed is greater than 3600 rpm, the switching frequency of the drive signal is set to 18000 Hz.

[0086] In some embodiments, the controller is configured to: determine the switching frequency of the drive signal based on a first parameter of the motor, and update the switching frequency based on a second parameter.

[0087] The first parameter includes the motor speed; the second parameter includes at least one of the motor torque, motor current, motor bus voltage, and controller temperature; the switching frequency increases with the increase of motor speed within each speed range; or, the switching frequency increases with the increase of motor speed between each speed range.

[0088] It should be noted that, in this embodiment, the switching frequency of the drive signal can be determined according to the method for determining the switching frequency of the drive signal based on the motor speed provided in any of the above embodiments, and will not be repeated here.

[0089] It should also be noted that in this embodiment, the switching frequency can be determined according to the method provided in any of the above embodiments, which determines the switching frequency adjustment coefficient k based on preset conditions and updates the switching frequency based on the switching frequency adjustment coefficient k. This will not be elaborated further here.

[0090] In some embodiments, when the second parameter includes the motor torque or current, the controller is configured to reduce the switching frequency when the torque is less than a torque threshold or the current is less than a current threshold.

[0091] In some embodiments, when the second parameter includes the bus voltage, the controller is configured to reduce the switching frequency when the bus voltage is less than a voltage threshold.

[0092] In some embodiments, when the second parameter includes the controller temperature, the controller is configured to: increase the switching frequency when the controller temperature is less than a first temperature threshold, and decrease the switching frequency when the controller temperature is greater than a second temperature threshold.

[0093] The first temperature threshold is less than the second temperature threshold.

[0094] Among them, the torque threshold, current threshold, voltage threshold, first temperature threshold, and second temperature threshold can all be determined according to the requirements of the switching loss and control accuracy of the manned lawnmower.

[0095] By reducing the switching frequency when the torque is less than the torque threshold, the current is less than the current threshold, the bus voltage is less than the voltage threshold, or the controller temperature is greater than the second temperature threshold, the switching losses and heat generation of the manned lawnmower can be reduced, which is beneficial to improving the endurance and reliability of the manned lawnmower. At the same time, increasing the switching frequency when the controller temperature is less than the first temperature threshold helps to reduce NVH noise.

[0096] In some embodiments, when the second parameter includes at least two of the motor torque, motor current, voltage bus, and controller temperature, the controller is configured to: update the switching frequency according to the motor torque, motor current, voltage bus, and controller temperature respectively, and control the motor operation according to the smallest of the updated switching frequencies as the updated switching frequency, so that the switching frequency of the drive signal is set more conservatively, thereby ensuring the reliability of the manned lawnmower and improving the service life of the manned lawnmower.

[0097] In some embodiments, when the motor speed is less than a speed threshold, the controller is configured to set the switching frequency to a preset value.

[0098] The rotational speed threshold is determined based on the requirements for switching losses and control precision of the manned lawnmower. In some embodiments, the rotational speed threshold is 200 rpm, with a preset value of 5000 Hz. In some embodiments, the rotational speed threshold is 1800 rpm, with a preset value of 10000 Hz.

[0099] In some embodiments, the switching frequency of the drive signal is controlled to switch from a first switching frequency to a second switching frequency based on relevant parameters, so as to reduce the switching losses of the drive circuit.

[0100] The relevant parameters include at least one of the following: motor speed, motor torque, motor current, bus voltage, and controller temperature.

[0101] Based on the same inventive concept, this embodiment also provides a control method for a manned lawnmower. Figure 7 is a flowchart of a control method for a manned lawnmower provided in this application embodiment. Referring to Figure 7, the control method includes:

[0102] S110. Based on the first parameter and the preset switching frequency curve, set the switching frequency of the drive circuit.

[0103] The preset switching frequency curve is a speed-switching frequency relationship curve preset according to the characteristics of the motor. In some embodiments, the preset switching frequency curve is shown in Figure 3. In some embodiments, the preset switching frequency curve is shown in Figure 5. In some embodiments, the preset switching frequency curve is shown in Figure 6.

[0104] S120, Update the switching frequency based on the second parameter.

[0105] The first parameter and the second parameter respectively include at least one of the following: motor speed, motor torque, motor current, bus voltage, and controller temperature; the switching frequency increases with the increase of motor speed within each of the said speed ranges; or, the switching frequency increases with the increase of motor speed between each speed range.

[0106] S130: Based on the updated switching frequency, output a drive signal to control the motor operation.

[0107] The control method for the manned lawnmower provided in this application embodiment can perform the corresponding functions of power tools and has corresponding beneficial effects. The similarities can be referred to the description above.

[0108] The foregoing has shown and described the basic principles, main features, and advantages of this application. Those skilled in the art should understand that the above embodiments do not limit this application in any way, and all technical solutions obtained by equivalent substitution or equivalent transformation fall within the protection scope of this application.

Claims

1. A manned lawn mower, comprising: A motor that operates at least in a first speed range and a second speed range; An output member, wherein the motor drives the output member to perform the functions of the manned lawn mower; A power supply device that is at least used to supply power to the motor; A drive circuit including a plurality of switching elements electrically connected between the power supply device and the motor; A controller that is at least electrically connected to the drive circuit; The controller is configured to output a drive signal to the drive circuit to cause the motor to operate; the drive signal at least includes a switching frequency; The controller is set to control the switching frequency of the drive signal to be a first switching frequency f1 when the speed of the motor is in the first speed range, and to control the switching frequency of the drive signal to be a second switching frequency f2 when the speed of the motor is in the second speed range; wherein, the first switching frequency f1 has a first positive correlation with the speed of the motor, and the second switching frequency f2 has a second positive correlation with the speed of the motor.

2. The manned lawnmower according to claim 1, wherein, The maximum speed of the first speed range is less than or equal to the minimum speed of the second speed range; the first switching frequency f1 = M1 * P * n / 60, the second switching frequency f2 = M2 * P * n / 60, where P is the number of pole pairs of the motor, n is the speed of the motor, M1 is the number of control times within the electrical angle period of the motor in the first speed range, M2 is the number of control times within the electrical angle period of the motor in the second speed range, and M1 is greater than M2.

3. The manned lawnmower according to claim 1, wherein, The motor also operates in a third speed range; the maximum speed of the third speed range is less than or equal to the minimum speeds of the first speed range and the second speed range; The controller is further configured to: when the speed of the motor is in the third speed range, control the switching frequency of the drive signal to be a third switching frequency f3; the third switching frequency f3 is less than the first switching frequency f1 and the second switching frequency f2.

4. The manned lawnmower according to claim 1, wherein, The controller is further configured to: determine a switching frequency adjustment coefficient k based on a preset condition, and update the first switching frequency f1 and the second switching frequency f2 based on the switching frequency adjustment coefficient k.

5. The manned lawnmower according to claim 3, wherein, The controller is further configured to: determine a switching frequency adjustment coefficient k based on a preset condition, and update the first switching frequency f1, the second switching frequency f2, and the third switching frequency f3 based on the switching frequency adjustment coefficient k.

6. The manned lawnmower according to claim 5, wherein, When the motor is stationary or stalled, the switching frequency of the drive signal is a stationary switching frequency f0; wherein, f0 < f3; the value range of the switching frequency adjustment coefficient k is determined according to a first formula; wherein, the first formula is as follows: f0 / f3 < k < f1max / f2max; where fmax is the highest switching frequency theoretically allowed by the drive circuit; f2max is the highest switching frequency actually allowed by the drive circuit.

7. The manned lawnmower according to claim 6, wherein, The preset condition includes at least one of the torque of the motor, the current of the motor, the bus voltage of the motor, and the temperature of the controller.

8. The manned lawnmower according to claim 1, wherein, The motor includes a walking motor; the output component includes a walking wheel; the walking motor is used to drive the walking wheel to rotate.

9. The manned lawnmower according to claim 1, wherein, The motor includes a mowing motor; the output component includes a mowing mechanism; the mowing motor is used to drive the mowing mechanism to rotate.

10. The manned lawnmower according to claim 1, wherein, The maximum output power of the motor is less than or equal to 50kW.

11. The manned lawnmower according to claim 1, wherein, The power supply includes at least one battery pack; the battery pack is detachably mounted to the manned lawnmower.

12. The manned lawnmower according to claim 1, wherein, The switching frequency increases with the increase of the motor speed within each of the speed ranges.

13. The manned lawnmower according to claim 12, wherein, The switching frequency increases with the increase of the motor speed in each speed range.

14. The manned lawnmower according to claim 1, wherein, The switching frequency varies with the motor speed across different speed ranges. The controller is configured to: determine the switching frequency of the drive circuit based on a first parameter of the motor, and update the switching frequency based on a second parameter.

15. The manned lawnmower according to claim 14, wherein, The first parameter includes the rotational speed of the motor; the second parameter includes at least one of the torque of the motor, the current of the motor, the bus voltage of the motor, and the temperature of the controller; the switching frequency increases with the increase of the rotational speed of the motor within each of the rotational speed ranges; or, the switching frequency increases with the increase of the rotational speed of the motor between each rotational speed range.

16. A manned lawnmower, comprising: Electric motor; The output component is driven by the motor to perform the functions of the manned lawnmower. A power supply device, at least for supplying power to the motor; The drive circuit includes a plurality of switching elements electrically connected between the power supply device and the motor; The controller is at least electrically connected to the drive circuit; The controller is configured to output a drive signal to the drive circuit to make the motor run; the drive signal includes at least a switching frequency. The controller is configured to determine the switching frequency of the drive circuit based on a first parameter of the motor, and update the switching frequency based on a second parameter. The first parameter includes the motor speed; the second parameter includes at least one of the motor torque, the motor current, the motor bus voltage, and the controller temperature; the switching frequency increases with the increase of the motor speed in each of the speed ranges.

17. The manned lawnmower according to claim 16, wherein, When the second parameter includes the torque or current of the motor, the controller is configured to reduce the switching frequency when the torque is less than a torque threshold or the current is less than a current threshold.

18. The manned lawnmower according to claim 16, wherein, When the second parameter includes the bus voltage, the controller is configured to reduce the switching frequency when the bus voltage is less than a voltage threshold.

19. A control method for a manned lawnmower, the manned lawnmower comprising: Electric motor; The motor operates at least in a first speed range and a second speed range; The output component is driven by the motor to perform the functions of the manned lawnmower. A power supply device, at least for supplying power to the motor; The drive circuit includes a plurality of switching elements electrically connected between the power supply device and the motor; The controller is at least electrically connected to the drive circuit; The controller is used to output a drive signal to the drive circuit to make the motor run; the drive signal includes at least a switching frequency. The control method includes: Based on the first parameter and the preset switching frequency curve, the switching frequency of the driving circuit is set. The switching frequency is updated based on the second parameter; Based on the updated switching frequency, a drive signal is output to control the operation of the motor; Wherein, the first parameter and the second parameter respectively include at least one of the motor speed, motor torque, motor current, bus voltage and controller temperature; the switching frequency increases with the increase of the motor speed within each of the speed ranges; or, the switching frequency increases with the increase of the motor speed between each speed range.

20. The control method according to claim 19, wherein, When the second parameter includes the torque or current of the motor, the controller is configured to reduce the switching frequency when the torque is less than a torque threshold or the current is less than a current threshold.

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