Starting device, motor system and method for reducing starting current of direct current motor
By periodically switching the state of the switching elements in the DC motor circuit, the problem of high peak starting current of DC motors is solved, reducing the risk of component damage and cost.
Patent Information
- Application Number
- CN202310841321.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2023-07-10
- Publication Date
- 2025-01-10
AI Technical Summary
The high peak starting current of existing DC motors leads to high component selection costs and easy damage, making it difficult to effectively reduce the current.
By connecting a switching element in series in the DC motor and DC power supply circuit, and using the control unit to periodically switch the switching element between the on and off states within a preset time interval, the peak starting current is reduced, and the on state is maintained after the time interval ends.
It effectively reduces the peak starting current of DC motors, reduces the risk of component damage, and lowers product costs.
Smart Images
Figure CN119298726A_ABST
Abstract
Description
Technical Field
[0001] The present application relates to motor control technology, and in particular to a starting device for a DC motor, a motor system including the starting device, a method for reducing the starting current of a DC motor, and a computer-readable storage medium storing a computer program for implementing the above method. Background Art
[0002] The starting current of a brushed DC motor usually has a high peak value, which is typically several times the rated current. To this end, high-specification and high-quality electronic components (such as metal-oxide semiconductor field effect transistors (MOSFETs), current sampling resistors, fuses, and windings, etc.) need to be selected, which leads to high product costs. In addition, even if the above technical measures have been taken, the burning of components is still difficult to avoid during long-term use. Therefore, reducing the starting current of the motor is an urgent problem that needs to be solved. Summary of the invention
[0003] According to one aspect of the present application, there is provided a starting device for a DC motor, comprising:
[0004] A switch element, which is connected in series in a loop including the DC motor and the DC power supply;
[0005] A control unit is configured to periodically switch the switch element between an on state and an off state within a preset time interval to reduce a peak value of a starting current flowing through the DC motor, and to keep the switch element in the on state after the preset time interval ends.
[0006] Optionally, the above starting device further includes an overcurrent protection element coupled between the DC power supply and the DC motor.
[0007] Optionally, the above starting device further includes a capacitor connected between the positive pole and the negative pole of the DC motor to absorb the electromagnetic pulse component generated by the DC motor.
[0008] In addition to one or more of the above features, in the above starting device, the switching element is a metal-oxide semiconductor field effect transistor, whose gate is coupled to the control unit, one of its source and drain is coupled to the positive pole or negative pole of the DC motor, and the other is coupled to the ground.
[0009] Optionally, in the starting device, the control unit causes the switching element to periodically switch between an on state and an off state by applying a pulse width modulation signal to the gate.
[0010] Optionally, in the starting device, the frequency of the pulse width modulation signal is set so that a value of the starting current at the beginning of the preset time interval is smaller than a first threshold.
[0011] Optionally, in the starting device, the length of the preset time interval is set to be greater than a second threshold value, so that the value of the starting current at the beginning of the preset time interval is greater than the value when the switching element starts to maintain the on state.
[0012] According to another aspect of the present application, there is provided a motor system, comprising:
[0013] a DC motor including a positive pole and a negative pole; and
[0014] Starting device, including:
[0015] A switch element, which is connected in series in a loop including the DC motor and the DC power supply;
[0016] A control unit is configured to periodically switch the switch element between an on state and an off state within a preset time interval to reduce a peak value of a starting current flowing through the DC motor, and to keep the switch element in the on state after the preset time interval ends.
[0017] According to another aspect of the present application, a method for reducing a starting current of a DC motor is provided, comprising:
[0018] Periodically switching a switch element connected in series in a loop including the DC motor and the DC power supply between an on state and an off state within a preset time interval to reduce a peak value of a starting current flowing through the DC motor; and
[0019] After the preset time interval has elapsed, the switch element is maintained in the conductive state.
[0020] According to another aspect of the present application, a computer-readable storage medium is provided, on which a computer program suitable for being executed on a processor of a terminal device is stored, and the execution of the computer program causes the steps of the method described above to be performed. BRIEF DESCRIPTION OF THE DRAWINGS
[0021] The above and / or other aspects and advantages of the present application will become clearer and easier to understand through the following description of various aspects in conjunction with the accompanying drawings, in which the same or similar units are represented by the same reference numerals. The accompanying drawings include:
[0022] Figure 1 It is a schematic block diagram of a starting device for a DC motor according to some embodiments of the present application.
[0023] Figure 2 The schematic circuit diagram is a specific scheme of a starting device for a DC motor according to some other embodiments of the present application.
[0024] Figure 3 It is shown as an example Figure 2 The circuit shown shows the relationship between the starting current and time in the DC motor starting method according to the prior art.
[0025] Figure 4 It is shown as an example Figure 2 The circuit shown shows the relationship between the starting current and time in the DC motor starting mode according to some embodiments of the present application.
[0026] Figure 5 The present invention is a flowchart of a method for reducing the starting current of a DC motor according to some other embodiments of the present application.
[0027] Figure 6 A schematic block diagram of a typical control device. DETAILED DESCRIPTION
[0028] The present application is described more fully below with reference to the accompanying drawings in which illustrative embodiments of the present application are illustrated. However, the present application may be implemented in different forms and should not be interpreted as being limited to the embodiments given herein. The above embodiments are given to make the disclosure herein comprehensive and complete, so as to more fully convey the scope of protection of the present application to those skilled in the art.
[0029] In this specification, terms such as "comprise" and "include" indicate that in addition to the units and steps directly and explicitly stated in the specification and claims, the technical solution of the present application does not exclude the situation where there are other units and steps that are not directly or explicitly stated.
[0030] In this specification, terms such as "A is coupled to B" and "A is coupled to B" indicate the following situations: i) there is a direct electrical connection or mechanical connection between A and B; ii) an electrical connection or mechanical connection is established between A and B through C.
[0031] Unless otherwise specified, in this specification, terms such as "first" and "second" do not indicate the order of units in terms of time, space, size, etc., but are only used to distinguish between units.
[0032] Figure 1 is a schematic block diagram of a starting device for a DC motor according to some embodiments of the present application. It should be noted that, in addition to Figure 1 In addition to the units shown, the starting device also includes other units that are essential for implementing the starting function. However, for the sake of simplicity, Figure 1The description will only concern those units directly related to the subject of reducing starting current.
[0033] Figure 1 The starting device 10 shown includes a switch element 110 and a control unit 120. Figure 1 , the positive pole and negative pole of the DC motor 11 are coupled to the DC power source 12 and the switch element 110, respectively. It should be noted that, in addition to the illustrated case, the switch element 110 may also be connected in series at other positions in the loop L including the DC motor 11 and the DC power source 12, for example, the switch element 110 may be located between the positive pole of the DC motor 11 and the DC power source 12.
[0034] On the other hand, the control unit 120 is coupled to the control end of the switch element 110 to control the on-off state of the switch element 110. In some embodiments, the control unit 120 adjusts the peak value of the starting current (hereinafter referred to as the peak starting current) I of the DC motor 11 by controlling the on-off state of the switch element 110. p Specifically, at a preset time interval T s The control unit 120 can periodically switch the switch element 110 between the on state ON and the off state OFF, thereby reducing the peak starting current I flowing through the DC motor. p The preset time interval T s This corresponds to the starting phase of the DC motor 11, and can therefore be understood as the starting period of the DC motor. After the starting period ends, the control unit 120 keeps the switch element 110 in the conducting state ON.
[0035] In some examples, the switching element 100 can be implemented using a metal-oxide semiconductor field effect transistor (MOSFET), the gate G of which is coupled to the control unit 120, one of the source S and the drain D is coupled to the positive or negative pole of the DC motor 11, and the other is coupled to the ground.
[0036] Figure 2 The schematic circuit diagram is a specific scheme of a starting device for a DC motor according to some other embodiments of the present application.
[0037] exist Figure 2 In the circuit 20 shown, the switch element is implemented by an NMOS tube T1, whose gate G is connected to the control unit 120 via a resistor R1 and grounded via a voltage-dividing resistor R2, the drain D is connected to the negative electrode of the DC motor 11, and the source S is grounded via a current sampling resistor R3. It should be noted that the type of MOS tube shown here is only exemplary, and in some alternative implementations, a PMOS tube can also be used as the switch element 110. In addition, Figure 2The connection method of the MOS tube and the DC motor and other units shown and their positions in the circuit are only exemplary. Other replaceable methods include, but are not limited to: the source S of the NMOS tube T1 is coupled to the negative electrode of the DC motor 11, and the drain D is grounded via the current sampling resistor R3; or the NMOS tube T1 is coupled between the DC power supply 12 and the positive electrode of the DC motor 11, wherein the source S (drain D) is coupled to the DC power supply 12, and the drain D (source S) is coupled to the positive electrode of the DC motor 11.
[0038] Continue to see Figure 2 The circuit 20 further includes an overcurrent protection element F (such as a fuse) connected between the DC power supply 12 and the positive pole of the DC motor 11 and a capacitor C (which is used to absorb the electromagnetic pulse component generated by the DC motor) connected between the positive pole and the negative pole of the DC motor 11. The circuit 20 further includes a diode D reversely connected between the positive pole and the negative pole of the DC motor 11.
[0039] exist Figure 2 In the illustrated embodiment, the control unit 120 can apply a pulse width modulation (PWM) signal to the gate G to implement periodic switching of the switch element (taking the NMOS transistor T1 as a specific example) between the on state ON and the off state OFF.
[0040] Figure 3 It is shown as an example Figure 2 The relationship between the starting current and time of the circuit shown in the figure under the DC motor starting method according to the prior art, wherein the horizontal axis represents time and the vertical axis represents the starting current I measured at the positive pole of the DC motor s and the voltage V measured at the negative pole of the DC motor. In particular, Figure 3 In the figure, ① represents the starting current I of the DC motor 11 s The curve of change with time, ② represents the curve of change of voltage V with time.
[0041] When the control signal applied to the gate G changes from a low level to a high level, the circuit where the DC motor is located quickly switches from an open state to a closed state. Figure 3 As shown, the voltage V changes from a high potential to a low potential, and the starting current I s At maximum or peak I p ; After that, the starting current I s As time goes by, the current gradually decreases until it reaches or approaches a constant current value I constant .
[0042] Figure 4 It is shown as an example Figure 2The relationship between the starting current and time of the circuit shown in the DC motor starting mode according to some embodiments of the present application, wherein the horizontal axis represents time and the vertical axis represents the starting current I measured at the positive pole of the DC motor s and the voltage V measured at the negative pole of the DC motor. In particular, Figure 3 In the figure, ③ represents the starting current I of the DC motor 11 s The curve of change with time, ④ represents the curve of change of voltage V with time.
[0043] See also Figure 4 , different from Figure 3 The startup method shown in the figure is to start the s In the embodiment, the control signal applied to the gate G is provided in the form of a PWM signal, so the switch element 110 or the MOS tube T1 is periodically switched between the on state ON and the off state OFF, and accordingly, the voltage V is periodically switched between the high potential and the low potential, and the startup current I s At time interval T s The peak I appears at the beginning of p1 And it gradually decreases in a wave-like manner as time goes by; at the time interval T s After the end of the shutdown, the control signal applied to the gate G remains at a high level, the switch element remains in the ON state, and accordingly, the voltage V remains at a low potential, and the startup current I s When the switch element starts to maintain the ON state, it jumps to another peak value I p2 And it gradually decreases with the passage of time until it reaches or approaches a constant current value I constant By comparison Figure 3 and 4 visible, Figure 4 The peak starting current I p1 and peak starting current I p2 Less than Figure 3 The peak starting current I p That is, by periodically switching the switching element between the on state and the off state, the peak value of the starting current flowing through the DC motor can be reduced.
[0044] After in-depth research, the inventor of the present application found that by selecting the frequency of the PWM signal applied to the gate G, the peak starting current peak value I p1 and peak starting current I p2 In particular, as the PWM signal frequency increases, the peak starting current I p1 and peak starting current I p2 Will decrease accordingly.
[0045] After in-depth research, the inventor of the present application also found that, contrary to intuitive understanding, when a PWM signal is applied to the control end of the switching element, the peak starting current I p1 Not always greater than the peak I p2 That is to say, only the peak starting current I p1 Controlling below the desired level does not ensure that the peak value of the starting current is below the desired level, which means that in order to reduce the peak value of the starting current, a higher PWM signal frequency needs to be selected, which faces more challenges in terms of cost and circuit design.
[0046] After further research, the inventor of the present application found that by setting the preset time interval T s is large enough to make the peak value I p1 Greater than peak I p2 .
[0047] Based on the above findings, in some embodiments of the present application, the following methods can be used to reduce the starting current of the DC motor: first, by selecting the frequency of the PWM signal applied to the gate G, the peak starting current peak value I p1 to the desired level; then by selecting a preset time interval T s To ensure peak I p1 Greater than peak I p2 Thus, the problems of increased cost and increased circuit design difficulty caused by adopting a higher PWM signal frequency can be avoided.
[0048] Figure 5 Flowchart of a method for reducing the starting current of a DC motor according to some other embodiments of the present application. By way of example, the method described below is Figure 1 Or the starting device shown in 2 is implemented.
[0049] Figure 5 The method shown includes the following steps:
[0050] Step 510 : The control unit 120 applies a PWM signal to the control terminal (eg, gate G) of the switch element 110 , for example, to periodically switch the switch element 110 between the on state and the off state.
[0051] Step 520: The control unit 120 determines whether a preset time interval T has elapsed since the PWM signal was applied. s , if the time interval T s , then go to step 530, otherwise return to step 510.
[0052] Step 530: The control unit 120 keeps the switch element 110 in the on state, for example, by constantly applying a high-level signal (if the switch element is an NMOS tube) or a low-level signal (if the switch element is a PMOS tube) to the control end (such as the gate G) of the switch element 110.
[0053] Optionally, the frequency of the PWM signal is set so that the starting current is s The initial value is smaller than the first threshold TH1.
[0054] Further optionally, the preset time interval T s The length of is set to be greater than the second threshold value TH2, so that the starting current is within the preset time interval T s The value at the beginning (peak value I p1 ) is greater than the value at which the switch element begins to remain in the on state (peak value I p2 ).
[0055] Figure 6 A schematic block diagram of a typical control device. Figure 6 The control device shown can be used to implement Figure 1 and 2 The control unit shown.
[0056] like Figure 6 As shown, the control device 60 includes a memory 610 (eg, a non-volatile memory such as a flash memory, a ROM, a hard disk drive, a magnetic disk, an optical disk, etc.), a processor 620 and a computer program 630 .
[0057] The memory 610 stores a computer program 630. The processor 620 is configured to execute the computer program 630 stored on the memory 620 to perform Figure 5 One or more steps included in the method shown.
[0058] According to another aspect of the present application, a computer-readable storage medium is also provided, on which a computer program (eg Figure 6 630), which is executed by a processor (e.g. Figure 6 The above can be achieved by using the processor 620 in Figure 5 One or more steps included in the method.
[0059] The computer-readable storage medium referred to in this application includes various types of computer storage media, which can be any available medium that a general or special-purpose computer can access. For example, a computer-readable storage medium can include RAM, ROM, EPROM, E2PROM, register, hard disk, removable disk, CD-ROM or other optical disk storage, disk storage or other magnetic storage device, or can be used to carry or store a desired program code unit with an instruction or data structure form and can be accessed by a general or special-purpose computer, or a general or special-purpose processor. Any other temporary or non-temporary medium. The above combination should also be included in the protection scope of the computer-readable storage medium. An exemplary storage medium is coupled to a processor so that the processor can read and write information from / to the storage medium. In an alternative, a storage medium can be integrated into a processor. The processor and the storage medium can reside in an ASIC. The ASIC can reside in a user terminal. In an alternative, the processor and the storage medium can reside in a user terminal as discrete components.
[0060] Those skilled in the art will appreciate that the various illustrative logical blocks, modules, circuits, and algorithm steps described herein may be implemented as electronic hardware, computer software, or a combination of both.
[0061] In order to show the interchangeability between hardware and software, various schematic components, blocks, modules, circuits and steps are generally described above according to their functionality. Such functionality is implemented in hardware form or software form depending on the specific application and the design restrictions imposed on the overall system. Those skilled in the art can implement the described functionality in a variable manner for specific specific applications, but such implementation decisions should not be understood as causing deviations from the scope of the present application.
[0062] Although only some of the specific embodiments of the present application are described, it should be understood by those skilled in the art that the present application can be implemented in many other forms without departing from its subject matter and scope. Therefore, the examples and embodiments shown are considered to be illustrative rather than restrictive, and the present application may include various modifications and substitutions without departing from the spirit and scope of the present application as defined in the appended claims.
[0063] The embodiments and examples set forth herein are provided to best illustrate embodiments according to the present technology and its specific applications, and thereby enable those skilled in the art to implement and use the present application. However, those skilled in the art will appreciate that the above description and examples are provided only for ease of illustration and example. The description set forth is not intended to cover all aspects of the present application or to limit the present application to the precise form disclosed.
Claims
1. A starting device for a DC motor, comprising: A switch element, which is connected in series in a loop including the DC motor and the DC power supply; A control unit is configured to periodically switch the switch element between an on state and an off state within a preset time interval to reduce a peak value of a starting current flowing through the DC motor, and to keep the switch element in the on state after the preset time interval ends.
2. The starting device according to claim 1, wherein: An overcurrent protection element is also included which is coupled between the DC power supply and the DC motor.
3. The starting device according to claim 1, wherein: It also includes a capacitor connected between the positive pole and the negative pole of the DC motor to absorb the electromagnetic pulse component generated by the DC motor.
4. The starting device according to any one of claims 1 to 3, wherein: The switch element is a metal-oxide semiconductor field effect transistor, a gate of which is coupled to the control unit, one of a source and a drain of which is coupled to the positive electrode or the negative electrode of the DC motor, and the other is coupled to the ground.
5. The starting device according to claim 4, wherein: The control unit periodically switches the switching element between an on state and an off state by applying a pulse width modulation signal to the gate.
6. The starting device according to claim 5, wherein: The frequency of the pulse width modulation signal is set so that the value of the starting current at the beginning of the preset time interval is less than a first threshold.
7. The starting device according to claim 6, wherein: The length of the preset time interval is set to be greater than a second threshold value, so that the value of the starting current at the beginning of the preset time interval is greater than the value of the switching element when it starts to maintain the conducting state.
8. A motor system comprising: A DC motor, which contains a positive pole and a negative pole; as well as Starting device, including: A switch element, which is connected in series in a loop including the DC motor and the DC power supply; A control unit is configured to periodically switch the switch element between an on state and an off state within a preset time interval to reduce a peak value of a starting current flowing through the DC motor, and to keep the switch element in the on state after the preset time interval ends.
9. The motor system of claim 8, wherein: The starting device also includes an overcurrent protection element coupled between the DC power supply and the DC motor.
10. The motor system of claim 8, wherein: The starting device also includes a capacitor connected between the positive pole and the negative pole of the DC motor to absorb the electromagnetic pulse component generated by the DC motor.
11. The motor system according to any one of claims 8 to 10, wherein: The switch element is a metal-oxide semiconductor field effect transistor, a gate of which is coupled to the control unit, one of a source and a drain of which is coupled to the positive electrode or the negative electrode of the DC motor, and the other is coupled to the ground.
12. The motor system of claim 11, wherein: The control unit periodically switches the switching element between an on state and an off state by applying a pulse width modulation signal to the gate.
13. The motor system of claim 12, wherein: The frequency of the pulse width modulation signal is set so that the value of the starting current at the beginning of the preset time interval is less than a first threshold.
14. The motor system of claim 13, wherein: The length of the preset time interval is set to be greater than a second threshold value, so that the value of the starting current at the beginning of the preset time interval is greater than the value of the switching element when it starts to maintain the conducting state.
15. A method for reducing a starting current of a DC motor, comprising: At a preset time interval, a switch element connected in series in a loop including the DC motor and the DC power supply is periodically switched between an on state and an off state to reduce a peak value of a starting current flowing through the DC motor; as well as After the preset time interval has elapsed, the switch element is maintained in the conductive state.
16. The method of claim 15, wherein: The switching element is implemented using a metal-oxide semiconductor field effect transistor.
17. The method of claim 16, wherein: The switching element is periodically switched between an on state and an off state by applying a pulse width modulation signal to the gate of the metal-oxide semiconductor field effect transistor.
18. The method of claim 17, wherein: The frequency of the pulse width modulation signal is set so that the value of the starting current at the beginning of the preset time interval is less than a first threshold.
19. The method of claim 18, wherein: The length of the preset time interval is set to be greater than a second threshold value, so that the value of the starting current at the beginning of the preset time interval is greater than the value of the switching element when it starts to maintain the conducting state.
20. A computer-readable storage medium, wherein instructions are stored in the computer-readable storage medium, characterized in that: When the instructions are executed by a processor, the processor is caused to perform the method according to any one of claims 15 to 19.