Brake control method, control device and computer-readable medium

Abstract

The present invention discloses a brake control method, a control device and a computer-readable medium, the brake control method comprising the following steps: detecting the voltage value of a voltage divider resistor R 12 ; Calculating a first bus voltage value according to the voltage value of the voltage divider resistor R 12; Detecting the change in bus voltage within a first period and calculating a voltage change rate by an MCU; Calculating a second bus voltage value within a second period according to the voltage change rate, wherein the second bus voltage value is the estimated bus voltage value; Determining the relationship between the estimated bus voltage value and a predetermined value, wherein, if the estimated bus voltage value is greater than the predetermined value, the slow braking is stopped, and if the estimated bus voltage value is less than the predetermined value, the slow braking is continued.In the present invention, during slow braking, by estimating the bus voltage value, the braking operation can be performed or stopped in advance to solve the problems of voltage increase and the resulting damage to electronic components, and at the same time avoid the problems of excessive braking torque, unstable braking transition, and generation of unpleasant feeling to the user.

Description

Field of the invention

[0001] The present invention relates to the field of power tools and, more particularly, to a brake control method, a control device and a computer-readable medium. State of the art

[0002] For handheld power tools such as electric wrenches and electric circular saws, direct braking when a brushless motor is turned off results in an instantaneous, extremely high braking torque, which causes significant reaction force from the tool and also causes discomfort for the user during use and a loud noise. Slow braking when turning off reduces the counterforce and noise level of the tool. However, repeated switching on and off of the switching transistors causes current to flow back, causing excessive voltage, damaging the MOS tubes and affecting the service life of the power tool.

[0003] Reference is made to Chinese Utility Model CN213342062U, published on June 1, 2021, which discloses that, when the switch is off, the control module controls at least two upper switching transistors or at least two lower switching transistors of the inverter circuit with a first duty cycle of less than 100% so that an electrical connection is established between the switching transistors for braking. When the voltage detected by the peak voltage detection module exceeds the predetermined value stored in the control module, the control module controls at least the two upper switching transistors or the at least two lower switching transistors with a second duty cycle of 100% so that an electrical connection is established between the switching transistors for braking.While this controls the peak voltage generated during early braking, it does not control the strong braking force generated during late braking. This still results in loud noise and creates an unpleasant feeling for the user.

[0004] Therefore, it is necessary to develop a braking device and braking method for brushless DC motors that can solve the above problems. Object of the invention

[0005] The invention is based on the object of avoiding the above-mentioned disadvantages of the prior art and of providing a braking device and a braking method for brushless DC motors, by which the problems of voltage increase and the resulting damage to electronic components can be solved and at the same time the problems of excessive braking torque, unstable braking transition and the generation of an unpleasant feeling for the user can be avoided.

[0006] To solve the technical problems existing in the prior art, the present invention uses the following technical solutions: A brake control method comprising the following steps: S1: Detecting the voltage value of a voltage divider resistor R 12 ; S2: Calculate a first bus voltage value according to the voltage value of the voltage divider resistor R 12 ; S3: Detecting the change in bus voltage within a first period and calculating a voltage change rate; S4: Calculating a second bus voltage value within a second period according to the voltage change rate, wherein the second bus voltage value is the estimated bus voltage value; S5: Determining the relationship between the estimated bus voltage value and a predetermined value, wherein, if the estimated bus voltage value is greater than the predetermined value, the slow braking is stopped, and if the estimated bus voltage value is less than the predetermined value, the slow braking is continued.

[0007] A further improvement of the solution is that for slow braking the PWM duty cycle of the upper three transistors is 0 and for the lower three transistors a modulation signal with a gradually increasing initial duty cycle is used.

[0008] A further improvement of the solution is that the initial duty cycle is in the range of 5% to 50%, while during slow braking the duty cycle always remains below 100%.

[0009] A further improvement of the solution is that the calculation method for the bus voltage value U gesamt is as follows: U gesamt = (R6 + R 12 ) ÷ R 12 × U ad , where U ad the voltage value at both ends of R 12 and R6 is the voltage divider resistor.

[0010] A further improvement of the solution is that the rate of change of voltage is the slope, where the calculation procedure for the slope is as follows: K = (U gesamt 2 = U gesamt 1 ) ÷ T, where K is the slope and T is the time in which the voltage value at the two ends of R 12 by U gesamt 1 on U gesamt 2 changes, is.

[0011] A further improvement of the solution is that when the estimated bus voltage value is greater than the predetermined value, a PWM modulation signal with a PWM duty cycle of 0 for the upper three transistors and a PWM duty cycle of 0 for the lower three transistors is output.

[0012] A further improvement of the solution: A brake control device, characterized in that the brake control device comprises: a voltage detection module used to detect the voltage value of a voltage divider resistor R 12 serves; a first calculation module configured to calculate a first bus voltage value according to the voltage value of the voltage divider resistor R 12 serves; a detection module configured to detect the change in bus voltage within a first period of time and calculate a voltage change rate; a second calculation module for calculating a bus voltage value; and a judgment module for determining the relationship between the estimated bus voltage value and a predetermined value, wherein, when the estimated bus voltage value is greater than the predetermined value, the slow braking is stopped, and when the estimated bus voltage value is less than the predetermined value, the slow braking is continued.

[0013] A further improvement of the solution: A brake control device, characterized in that the brake control device comprises: a voltage detection circuit for detecting the voltage value of a voltage divider resistor R 12 serves; an MCU used to perform the following tasks: Calculating a first bus voltage value according to the voltage value of the voltage divider resistor R 12; Detecting the change in bus voltage within a first period and calculating a voltage change rate; Calculating and estimating a bus voltage value; Determining the relationship between the estimated bus voltage value and a predetermined value, wherein, if the estimated bus voltage value is greater than the predetermined value, slow braking is stopped and, if the estimated bus voltage value is less than the predetermined value, slow braking is continued.

[0014] A further improvement of the solution: A mode control device, characterized in that the control device comprises a memory and a processor, wherein the memory stores a computer program executable by the processor.

[0015] A further improvement of the solution: A computer-readable medium, wherein the computer-readable medium contains non-transitory program code that is executable by the processor.

[0016] Compared with the prior art, the present invention achieves the following advantageous effects: When a brake signal is detected, the MOS tubes are driven with an initial duty cycle of 5% to 50%, gradually increasing the duty cycle at a fixed rate, and the modulation signal always remains below 100% for braking. The detection module always detects the voltage value of the voltage divider resistor in real time and transmits this value to the calculation module to calculate the bus voltage value for the next period. If the estimated bus voltage value is higher than the predetermined value stored in a power tool, the duty cycle of all six MOS tubes is 0, and braking is stopped until the estimated bus voltage value is lower than the predetermined value, at which point the power tool begins to brake again.By stopping the braking process early, damage to the MOS tubes due to excessive voltage can be prevented, thus extending the service life of the power tool. At the same time, excessive braking torque can be avoided, achieving a stable braking transition and providing a better feel for the user. Brief description of the drawings

[0017] In the following, specific embodiments are described in detail with reference to the figures. Fig. 1 shows a circuit diagram of the braking system for brushless DC motors according to the present invention; Fig. 2 shows a module diagram of the braking system for brushless DC motors according to the present invention; Fig. 3 shows a schematic diagram of the braking system for brushless DC motors according to the present invention, in which the bus voltage during braking is compared with the waveform of the PWM modulation signal; Fig. 4 shows a flowchart of the braking system for brushless DC motors according to the present invention. List of reference symbols 1 power module 2 voltage sensing module 3 Motor drive module 4 Engine 5 MCU Detailed description of the implementation examples

[0018] For a better understanding of the present invention, the embodiments are described in detail below with reference to the figures.

[0019] The braking method and device according to the present invention are suitable for intelligent devices such as power tools / electrical devices. These power tools / electrical devices can be garden tools, hand tools, or other automated devices with a slow braking function. As long as the devices / tools incorporate the essential concept of the technical solutions disclosed below, they fall within the scope of the present invention.

[0020] It is based on the Fig. 1 and Fig. 2. A braking device for brushless DC motors comprises a power module 1, a voltage sensing module 2, a brushless DC motor 4, an MCU 5, and a motor drive circuit 3. The power module is electrically connected to the motor drive circuit, the motor drive module is electrically connected to the brushless DC motor and controls the operation of the brushless DC motor, and the voltage sensing module is electrically connected to the MCU and serves to transmit the detected voltage value of a voltage dividing resistor to the MCU. The MCU includes an information processing module and a PWM control module (see Fig. 2). The information processing module is used to calculate a bus voltage value based on the received value of the voltage divider resistor, calculate the rate of change of the bus voltage (namely, the slope) within a certain period of time, calculate the change rate of the bus voltage in the next period of time based on the slope, and determine the estimated bus voltage value based on the change rate. Predefined values, namely the high bus threshold and the low bus threshold, are stored in the MCU. When the estimated bus voltage value reaches the high threshold, the PWM control module outputs a PWM modulation signal with a duty cycle of 0 for the upper three transistors and a duty cycle of 0 for the lower three transistors, thereby pausing braking.When the estimated bus voltage value reaches the lower threshold, the PWM control module controls the duty cycle of the upper three transistors to 0 and initiates braking through a modulation signal with an initial duty cycle that slowly increases at a fixed slope until the motor stops. The high threshold is the withstand voltage value of the bus voltage. Once the withstand voltage value is exceeded, damage to the MOS tubes and circuitry can easily occur, affecting the service life of the power tool. The low threshold ensures braking efficiency. Below this threshold, an increase in braking time and a decrease in braking efficiency can easily occur, affecting the user experience.

[0021] It will be Fig. 3. The reference value of the high threshold is 30V, and the reference value of the low threshold is 25V. The initial duty cycle is in the range of 5% to 50%, preferably 50%. The voltage sampling module transmits a detected voltage value to the information processing module. The information processing module is used to calculate the value of the voltage divider resistor to calculate the bus voltage value and the rate of change of the bus voltage, namely the slope, within a period of time. According to the slope, the change value of the bus voltage in the next period of time is calculated, and the estimated bus voltage value is determined according to the change value. When the estimated bus voltage value reaches the high threshold, that is, 30V, the PWM control module located in the MCU outputs a modulation signal with a duty cycle of the upper and lower transistors each of 0 to stop the braking operation.The detection process continues until the estimated bus voltage value reaches the low threshold, i.e. 25 V, at which point the PWM control module controls the duty cycle of the top three transistors to 0 and initiates braking by means of a modulation signal with an initial duty cycle of 50%, which slowly increases at a fixed slope while always remaining below 100%.

[0022] It will be Fig. 4. The present invention further provides a braking method for brushless DC motors, comprising the following steps: S1: Detecting the voltage value of a voltage divider resistor R 12 by a voltage detection module; S2: Calculating a first bus voltage value according to the voltage value of the voltage divider resistor R 12 by an MCU, whereby the calculation method for the bus voltage value U gesamt is as follows: U gesamt = (R6 + R 12 ) ÷ R12 × U ad , where U ad the voltage value at both ends of R 12 and R6 is the voltage divider resistor; S3: detecting the change in the bus voltage within a first period of time and calculating a voltage change rate, namely a slope K, by the MCU, the calculation method for the slope K being as follows: K = (U gesamt 2 - U gesamt 1 ) ÷ T, where T is the time during which the voltage value at the two ends of R 12 by U gesamt 1 on U gesamt 2changes; S4: Calculate the change value of the bus voltage in the next period according to the slope and determine the estimated bus voltage value according to the change value; S5: Determine the relationship between the estimated bus voltage value and a predetermined value, where the predetermined value is the high bus threshold or the low bus threshold. If the estimated bus voltage value is greater than the high threshold, a PWM modulation signal with a PWM duty cycle of 0 for the upper three transistors and a PWM duty cycle of 0 for the lower three transistors is output to stop slow braking.If the estimated bus voltage value is less than the low threshold, a PWM modulation signal is output to resume slow braking, with a PWM duty cycle of 0 for the upper three transistors and a gradually increasing initial duty cycle for the lower three transistors. The duty cycle of the upper three transistors is 0 and the initial duty cycle of the lower three transistors is in the range of 5% to 50%, preferably 50%. During the gradual increase, the duty cycle always remains below 100%. Here, the high threshold is the withstand voltage value of the bus voltage. Once the withstand voltage value is exceeded, it is easy to damage the MOS tubes and circuitry, affecting the service life of the power tool. The low threshold ensures braking efficiency.Below this threshold, braking time may increase and braking efficiency may decrease, affecting the user experience.

[0023] The present invention further provides a brake control device by which the above-mentioned braking methods are implemented. All braking methods can be implemented with the brake control device. The brake control circuit includes a voltage detection circuit configured to detect the voltage value of a voltage divider resistor R 12 and an MCU that serves to perform the following tasks: Calculating a first bus voltage value according to the voltage value of the voltage divider resistor R 12 , where the calculation method for the bus voltage value U gesamt is as follows: U gesamt = (R6 + R 12 ) ÷ R 12 × U ad , where U ad the voltage value at both ends of R 12and R6 is the voltage divider resistor; detecting the change in the bus voltage within a first period of time and calculating a voltage change rate, namely a slope K, the calculation method for the slope K being as follows: K = (U gesamt 2 - U gesamt 1) ÷ T, where T is the time during which the voltage value at the two ends of R 12 by U gesamt 1 on U gesamt 2changes; calculating the change value of the bus voltage in the next period according to the slope and determining the estimated bus voltage value according to the change value; determining the relationship between the estimated bus voltage value and a predetermined value, where the predetermined value is the high bus threshold or the low bus threshold. If the estimated bus voltage value is greater than the high threshold, a PWM modulation signal with a PWM duty cycle of 0 for the upper three transistors and a PWM duty cycle of 0 for the lower three transistors is output to stop the slow braking.If the estimated bus voltage value is less than the low threshold, a PWM modulation signal is output to resume slow braking, with a PWM duty cycle of 0 for the upper three transistors and a gradually increasing initial duty cycle for the lower three transistors. The duty cycle of the upper three transistors is 0 and the initial duty cycle of the lower three transistors is in the range of 5% to 50%, preferably 50%. During the gradual increase, the duty cycle always remains below 100%. Here, the high threshold is the withstand voltage value of the bus voltage. Once the withstand voltage value is exceeded, damage to the MOS tubes and circuitry can easily occur, affecting the service life of the power tool. The low threshold ensures braking efficiency.Below this threshold, braking time may increase and braking efficiency may decrease, affecting the user experience.

[0024] The present invention further provides a brake control device that implements the above-mentioned braking methods. All braking methods can be implemented with the brake control device. The brake control circuit comprises: a voltage detection module configured to detect the voltage value of a voltage dividing resistor R 12 and a first calculation module for calculating a first bus voltage value according to the voltage value of the voltage divider resistor R 12 serves, whereby the calculation method for the bus voltage value U gesamt is as follows: U gesamt = (R6 + R 12 ) ÷ R 12 × U ad , where U ad the voltage value at both ends of R 12and R6 is the voltage divider resistor; a detection module for detecting the change in the bus voltage within a first period of time and calculating a voltage change rate, namely a slope K, wherein the calculation method for the slope K is as follows: K = (U gesamt 2 - U gesamt 1 ) ÷ T, where T is the time during which the voltage value at the two ends of R 12 by U gesamt 1 on U gesamt 2changes; a second calculation module for calculating the change value of the bus voltage in the next period according to the slope and determining the estimated bus voltage value according to the change value; a judgment module for determining the relationship between the estimated bus voltage value and a predetermined value, where the predetermined value is the high bus threshold or the low bus threshold. When the estimated bus voltage value is greater than the high threshold, a PWM modulation signal with a PWM duty cycle of 0 for the upper three transistors and a PWM duty cycle of 0 for the lower three transistors is output to stop the slow braking.If the estimated bus voltage value is less than the low threshold, a PWM modulation signal is output to resume slow braking, with a PWM duty cycle of 0 for the upper three transistors and a gradually increasing initial duty cycle for the lower three transistors. The duty cycle of the upper three transistors is 0 and the initial duty cycle of the lower three transistors is in the range of 5% to 50%, preferably 50%. During the gradual increase, the duty cycle always remains below 100%. Here, the high threshold is the withstand voltage value of the bus voltage. Once the withstand voltage value is exceeded, it is easy to damage the MOS tubes and circuitry, affecting the service life of the power tool. The low threshold ensures braking efficiency.Below this threshold, braking time may increase and braking efficiency may decrease, affecting the user experience.

[0025] The present invention further provides a mode brake control device comprising a memory and a processor, the memory storing a computer program executable by the processor, the controller being for executing the computer program to implement the brake control method.

[0026] The present invention further provides a computer-readable medium containing non-transitory program code executable by the processor, the program code causing the processor to perform the brake control methods.

[0027] It will be clear to a person skilled in the art that, with regard to the specific working process of the device described above, for reasons of convenience and simplicity of description, reference may be made to the corresponding process in the above embodiments of the methods, which will not be further explained here.

[0028] If the functions are implemented in the form of software functional units and sold or used as stand-alone products, they may be stored on a computer-readable storage medium. Based on this understanding, the technical solutions of the present invention that contribute to the prior art may be realized substantially or in part in the form of a software product. The computer software product is stored on a storage medium and contains a plurality of instructions that cause a computing device (such as a personal computer, server, or network device) to perform all or part of the steps of the methods described in the various embodiments of the present invention.The storage medium can be a USB stick, a portable hard disk, a read-only memory (ROM), a random-access memory (RAM), a floppy disk, a CD, or any other medium on which the program code can be stored.

[0029] It should be noted that the above embodiments are only intended to illustrate the technical solutions of the present invention and are not intended to limit them. Although the present invention has been described in detail with reference to the above embodiments, it should be clear to those skilled in the art that they may nevertheless modify the technical solutions set forth in the above embodiments or make equivalent substitutions for some or all of the technical features. However, these modifications or equivalent substitutions do not cause the gist of the respective technical solutions to deviate from the scope of the technical solutions provided according to the embodiments of the present invention. All equivalent modifications and equivalent changes that can be made in accordance with the technical concepts of the present invention fall within the scope of the present invention.The scope of the invention is defined by the appended claims. QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] CN 213342062U

[0003]

Claims

[1] Brake control method, characterized by that it includes the following steps: S1: Detecting the voltage value of a voltage divider resistor R 12 ; S2: Calculate a first bus voltage value according to the voltage value of the voltage divider resistor R 12 ; S3: Detecting the change in bus voltage within a first period and calculating a voltage change rate; S4: Calculating a second bus voltage value within a second period according to the voltage change rate, wherein the second bus voltage value is the estimated bus voltage value; S5: Determining the relationship between the estimated bus voltage value and a predetermined value, wherein, if the estimated bus voltage value is greater than the predetermined value, the slow braking is stopped, and if the estimated bus voltage value is less than the predetermined value, the slow braking is continued. [2] Brake control method according to claim 1, characterized by that for slow braking the PWM duty cycle of the upper three transistors is 0 and for the lower three transistors a modulation signal with a gradually increasing initial duty cycle is used. [3] Brake control method according to claim 1, characterized by that the initial duty cycle is in the range of 5% to 50%, whereby during slow braking the duty cycle always remains below 100%. [4] Brake control method according to claim 1, characterized by that the calculation method for the bus voltage value U gesamt is as follows: U gesamt = (R6 + R 12 ) ÷ R 12 × U ad , where U ad the voltage value at both ends of R 12 and R6 is the voltage divider resistor. [5] Brake control method according to claim 1, characterized bythat the rate of change of voltage is the slope, where the calculation method for the slope is as follows: K = (U gesamt 2 - U gesamt 1 ) ÷ T, where K is the slope and T is the time in which the voltage value at the two ends of R 12 by U gesamt 1 on U gesamt 2 changes, is. [6] Brake control method according to claim 1, characterized by that when the estimated bus voltage value is greater than the predetermined value, a PWM modulation signal with a PWM duty cycle of 0 for the upper three transistors and a PWM duty cycle of 0 for the lower three transistors is output. [7] Brake control device, characterized by that it includes: a voltage detection module used to detect the voltage value of a voltage divider resistor R 12 serves; a first calculation module configured to calculate a first bus voltage value according to the voltage value of the voltage divider resistor R 12 serves; a detection module configured to detect the change in bus voltage within a first period of time and calculate a voltage change rate; a second calculation module for calculating a bus voltage value; and a judgment module for determining the relationship between the estimated bus voltage value and a predetermined value, wherein, when the estimated bus voltage value is greater than the predetermined value, the slow braking is stopped, and when the estimated bus voltage value is less than the predetermined value, the slow braking is continued. [8] Brake control device, characterized by that it includes: a voltage detection circuit for detecting the voltage value of a voltage divider resistor R12 serves; an MCU used to perform the following tasks: Calculating a first bus voltage value according to the voltage value of the voltage divider resistor R 12 ; Detecting the change in bus voltage within a first period and calculating a voltage change rate; Calculating and estimating a bus voltage value; Determining the relationship between the estimated bus voltage value and a predetermined value, wherein, if the estimated bus voltage value is greater than the predetermined value, slow braking is stopped and, if the estimated bus voltage value is less than the predetermined value, slow braking is continued. [9] Mode control device, characterized by that it comprises a memory and a processor; wherein the memory stores a computer program executable by the processor; wherein the controller is for executing the computer program to implement the brake control method according to any one of claims 1 to 7. [10] A computer-readable medium, the computer-readable medium containing non-transitory program code executable by the processor, characterized by that the program code causes the processor to execute the brake control method according to one of claims 1 to 7.

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