Motor rotating speed regulation and control system and method with duty ratio variable modulation mechanism

Abstract

The invention discloses a motor rotating speed regulation and control system with a duty ratio variable modulation mechanism and a motor rotating speed regulation and control method. The motor rotating speed regulation and control method is executed by a motor rotating speed regulation and control system with a duty ratio variable modulation mechanism. The motor rotating speed regulation and control system comprises a rotating speed detector and a motor driver. The motor driver modulates the duty ratio of a plurality of waveforms of a turn-on time signal according to the condition that the rotating speed of the motor detected by the rotating speed detector is greater than or equal to a set rotating speed, and modulates a duty ratio difference value between the duty ratio of each of the plurality of waveforms in the turn-on time signal and the duty ratio of the previous waveform or the duty ratio of other waveforms. The motor driver drives the motor according to the turn-on time signal, so that the rotating speed of the motor is limited below the set rotating speed.

Description

Technical Field

[0001] The present invention relates to a motor speed regulation system and method, and particularly to a motor speed regulation system and method with a duty ratio variable modulation mechanism. Background Art

[0002] In an electronic device, a fan motor is used to cool heat-generating components such as a processor. During the process of the fan motor cooling the heat-generating components, restricting the speed of the motor can make the fan motor exhibit the most appropriate cooling performance and properly cool the heat-generating components. However, the existing motor controller drives the motor in a way that the fan motor often operates unstably or abnormally when operating at a speed-limited state. Summary of the Invention

[0003] The present invention provides a motor speed regulation system and method with a duty ratio variable modulation mechanism for the deficiencies of the prior art. The motor speed regulation system of the present invention includes a speed detector and a motor driver. The speed detector is connected to the motor. The speed detector is configured to detect the speed of the motor. The motor driver is connected to the speed detector and the motor. The motor driver is configured to modulate the duty ratio of a plurality of waveforms sequentially generated in a conduction time signal and modulate a duty ratio difference between the duty ratio of each of the plurality of waveforms of the conduction time signal and the duty ratio of the previous one or each other one when the speed of the motor detected by the speed detector is greater than or equal to a set speed. The motor driver drives the motor according to the conduction time signal to limit the speed of the motor below the set speed.

[0004] On the other hand, the motor speed regulation method of the present invention includes the following steps: (a) using a motor driver to drive the motor to operate according to a conduction time signal; (b) using the motor driver to receive a target duty ratio command; (c) using the motor driver to set the duty ratio of the last generated one of the plurality of waveforms of the conduction time signal to be equal to a target duty ratio specified by the target duty ratio command; (d) using a speed detector to detect the speed of the motor; (e) using the motor driver to determine whether the speed of the motor is greater than or equal to a speed limit value, if not, sequentially execute steps (f) to (g) and then execute step (l), if so, sequentially execute steps (h) to (j); (f) using the motor driver to modulate a duty ratio difference between each of the plurality of waveforms of the conduction time signal in each time interval and each of the waveforms in the next time interval to be equal to an initial duty ratio difference; (g) using the motor driver to drive the motor according to the conduction time signal having the duty ratio difference equal to the initial duty ratio difference; (h) using the motor driver to set the duty ratio difference between the subsequent generated plurality of waveforms in the conduction time signal to be equal to a duty ratio modulation difference, where the duty ratio modulation difference is less than the initial duty ratio difference; (i) using the motor driver to drive the motor according to the conduction time signal having the duty ratio difference equal to the duty ratio modulation difference; (j) using the motor driver to determine whether the speed of the motor is greater than or equal to the speed limit value, if so, execute step (k), if not, execute step (l); (k) using the motor driver to reduce the duty ratio of each of the subsequent waveforms used to drive the motor; (l) using the motor driver to determine whether the duty ratio of the waveform currently used to drive the motor in the conduction time signal is equal to a target duty ratio, if so, do not execute step (m) and do not further modulate the conduction time signal, if not, execute step (m); and (m) using the motor driver to determine whether the duty ratio of the waveform currently used to drive the motor in the conduction time signal is greater than the target duty ratio, if so, reduce the duty ratio of each of the subsequent waveforms used to drive the motor, if not, increase the duty ratio of each of the subsequent waveforms used to drive the motor.

[0005] As described above, the present invention provides a motor speed regulation system and method with a duty cycle variable modulation mechanism. The motor speed regulation method of the present invention can be executed by the motor speed regulation system of the present invention (including a speed detector and a motor driver). In the motor speed regulation method of the present invention, no hysteresis operation is performed to avoid restricting the speed of the motor, resulting in the inability of the motor speed to quickly reach the target speed. In the motor speed regulation method of the present invention, as the speed of the motor changes due to various conditions and environmental factors, the duty cycle of each of the multiple waveforms of the conduction time signal for driving the motor is modulated, and the duty cycle difference between the multiple waveforms of the conduction time signal is modulated. Therefore, in the motor speed regulation method of the present invention, the motor can be driven to operate stably.

[0006] To further understand the features and technical content of the present invention, please refer to the following detailed description and drawings of the present invention. However, the provided drawings are only for reference and illustration, and are not used to limit the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] Figure 1 It is a block diagram of a motor speed regulation system with a duty cycle variable modulation mechanism according to the first embodiment of the present invention.

[0008] Figure 2 It is a block diagram of a motor speed regulation system with a duty cycle variable modulation mechanism according to the second embodiment of the present invention.

[0009] Figure 3 It is a block diagram of a motor speed regulation system with a duty cycle variable modulation mechanism according to the third embodiment of the present invention.

[0010] Figure 4 It is a flowchart of the steps of the motor speed regulation method according to the third embodiment of the present invention.

[0011] Figure 5 It is a circuit diagram of the output stage circuit and the drive circuit of a motor speed regulation system with a duty cycle variable modulation mechanism according to the fourth embodiment of the present invention and a single-phase motor.

[0012] Figure 6 It is a circuit diagram of the output stage circuit and the drive circuit of a motor speed regulation system with a duty cycle variable modulation mechanism according to the fifth embodiment of the present invention and a three-phase motor.

[0013] Figure 7 It is a timing diagram of a motor speed regulation system with a duty cycle variable modulation mechanism according to the sixth embodiment of the present invention entering the speed limit state.

[0014] Figure 8This is a schematic diagram showing that the motor speed control system with a duty cycle variable modulation mechanism according to the seventh embodiment of the present invention cancels the limited-rotation duty cycle modulation mode and returns to the general duty cycle control mode. DETAILED DESCRIPTION

[0015] The following is an explanation of the embodiments of the present invention through specific specific embodiments. Those skilled in the art can understand the advantages and effects of the present invention from the contents disclosed in this specification. The present invention can be implemented or applied through other different specific embodiments. Each detail in this specification can also be based on different viewpoints and applications, and each modification and change can be made without departing from the concept of the present invention. In addition, the drawings of the present invention are only simple schematic illustrations and are not depicted according to actual dimensions. It is stated in advance. The following embodiments will further explain the relevant technical contents of the present invention in detail, but the disclosed contents are not intended to limit the scope of protection of the present invention. In addition, the term "or" used in this article may include any one or more combinations of the associated listed items depending on the actual situation.

[0016] See also Figure 1 , which is a block diagram of a motor speed control system with a duty cycle variable modulation mechanism according to a first embodiment of the present invention. The motor speed control system according to the first embodiment of the present invention is applied to a driving motor MT.

[0017] In the first embodiment, the motor speed control system of the present invention includes a speed detector 200 and a motor driver 100. The motor driver 100 is connected to the speed detector 200 and the motor MT.

[0018] When the motor driver 100 drives the motor MT to operate, the rotation speed detector 200 detects the rotation speed RPM of the motor MT.

[0019] The motor driver 100 modulates the duty cycle of each of the multiple waveforms sequentially generated in an on-time signal according to the RPM of the motor MT obtained from the speed detector 200, and modulates a duty cycle difference between the duty cycle of each waveform of the multiple waveforms of the on-time signal and the duty cycle of the previous waveform or other waveforms.

[0020] The motor driver 100 drives the motor MT according to an on-time signal. For example, the motor driver 100 drives the motor MT during a duty cycle of each of the multiple waveforms of the on-time signal, and does not drive the motor MT during a non-duty cycle of each of the multiple waveforms of the on-time signal.

[0021] See also Figure 2, which is a block diagram of a motor speed control system with a duty cycle variable modulation mechanism according to the second embodiment of the present invention. The motor speed control system according to the second embodiment of the present invention is applied to drive a motor MT.

[0022] In the second embodiment, the motor speed control system of the present invention includes a speed detector 200 and a motor driver 100. The motor driver 100 may include a control circuit 101, a drive circuit 102, an output stage circuit 103, and a rotor position detection circuit 104.

[0023] In the motor driver 100, the control circuit 101 is connected to the rotor position detection circuit 104 and the drive circuit 102, and the output stage circuit 103 is connected to the drive circuit 102. The output stage circuit 103 is connected to the motor MT. The rotor position detection circuit 104 may be provided in the motor MT. The control circuit 101 is connected to the speed detector 200.

[0024] The rotor position detection circuit 104 can detect the position of the rotor of the motor MT to output a rotor position detection signal. The control circuit 101 can control the drive circuit 102 to drive the output stage circuit 103 to operate according to the position of the rotor of the motor MT indicated by a rotor position detection signal received from the rotor position detection circuit 104, thereby driving the motor MT to operate.

[0025] When the control circuit 101 controls the drive circuit 102 to drive the output stage circuit 103 to operate and thereby drive the motor MT (according to a rotor position detection signal received from the rotor position detection circuit 104), the speed detector 200 can detect the rotational speed RPM of the motor MT.

[0026] For example, the rotor position detection circuit 104 can judge the change in the position of the rotor of the motor MT based on a rotor position detection signal received multiple times from the rotor position detection circuit 104, and accordingly judge the rotational speed RPM of the motor MT.

[0027] It should be noted that the control circuit 101 can modulate the duty cycle in subsequent multiple waveforms of each conduction time signal among multiple conduction time signals, and modulate a difference (i.e., the duty cycle difference described herein) between the duty cycle of each waveform in each conduction time signal and the duty cycle of the previous waveform or other waveforms, according to the rotational speed RPM of the motor MT detected by the speed detector 200 being greater than or equal to a set rotational speed, so as to output multiple control signals.

[0028] The drive circuit 102 outputs multiple conduction time signals according to the multiple control signals received from the control circuit 101. The output stage circuit 103 operates according to the multiple conduction time signals received from the drive circuit 102 to drive the motor MT, so that the rotational speed of the motor MT is limited below a set rotational speed.

[0029] Please refer to Figure 3 and Figure 4 wherein Figure 3 is a block diagram of a motor speed regulation system with a duty cycle variable modulation mechanism according to the third embodiment of the present invention, Figure 4 is a flowchart of the steps of a motor speed regulation method according to the third embodiment of the present invention.

[0030] The motor speed regulation system according to the third embodiment of the present invention is applied to drive a motor MT.

[0031] In the third embodiment, the motor speed regulation system of the present invention includes a speed detector 200 and a motor driver 100 as shown in Figure 3 . The motor driver 100 may include a control circuit 101, a drive circuit 102, an output stage circuit 103, and a rotor position detection circuit 104.

[0032] It should be noted that, with respect to the function of the control circuit 101, as shown in Figure 3 , in the third embodiment, for example, the control circuit 101 may include a target limit comparison circuit 1011, a duty cycle setting circuit 1012, and a duty cycle modulation indication circuit 1013, but the present invention is not limited thereto.

[0033] As shown in Figure 3 the motor speed regulation system of the present invention can be used to execute the steps S101 to S114 as shown in Figure 4 , and the details are as follows.

[0034] In step S101, the duty cycle modulation indication circuit 1013 of the control circuit 101 drives the output stage circuit 103 to operate according to a conduction time signal, thereby driving the motor MT to operate normally. At this time, the duty cycle difference between each waveform of a conduction time signal output from the control circuit 101 to the output stage circuit 103 and the duty cycle DYOUT of each waveform in the next time interval is equal to a preset duty cycle difference or a default duty cycle difference.

[0035] In step S102, the target limit comparison circuit 1011 of the control circuit 101 receives a target duty cycle command DYTAG from an external target limit circuit and obtains a target duty cycle DYTG from this target duty cycle command DYTAG, or directly receives a target duty cycle DYTG from an external target limit circuit. This target duty cycle DYTG is used to drive the speed of the motor MT to reach a target speed.

[0036] The duty ratio setting circuit 1012 of the control circuit 101 sets the duty ratio DYOUT of the last generated waveform among the multiple waveforms of the conduction time signal to be equal to a target duty ratio DYTG.

[0037] In step S103, the rotation speed detector 200 detects the rotation speed RPM of the motor MT.

[0038] In step S104, the target limit ratio circuit 1011 of the control circuit 101 determines whether the rotation speed RPM of the motor MT is greater than or equal to a rotation speed limit value RPMLT. If the rotation speed RPM of the motor MT is not greater than a rotation speed limit value RPMLT, step S105 is executed. Conversely, if the rotation speed RPM of the motor MT is greater than or equal to a rotation speed limit value RPMLT, steps S106 and S107 are sequentially executed.

[0039] In step S105, the duty ratio setting circuit 1012 of the control circuit 101 sets an initial duty ratio difference. The duty ratio modulation instruction circuit 1013 of the control circuit 101 instructs the drive circuit 102 to modulate the duty ratio difference between the duty ratio DYOUT of each waveform among the multiple waveforms of the conduction time signal in each time interval and the duty ratio DYOUT of each waveform in the next time interval to be equal to this initial duty ratio difference.

[0040] The drive circuit 102 drives the output stage circuit 103 based on the conduction time signal with the duty ratio difference equal to the duty ratio modulation difference, thereby driving the motor MT.

[0041] That is to say, among the multiple waveforms of the conduction time signal, from the first generated waveform to the last generated waveform, the duty ratio DYOUT gradually increases from the initial duty ratio to the target duty ratio DYTG, and the rotation speed for driving the motor MT gradually increases from the initial rotation speed to the target rotation speed.

[0042] It should be understood that among the multiple waveforms of the conduction time signal described herein, the duty ratio difference between every two waveforms may be different from the duty ratio difference between other two waveforms.

[0043] In step S106, when the rotation speed RPM of the motor MT is greater than or equal to a rotation speed limit value RPMLT, the target limit ratio circuit 1011 of the control circuit 101 decides to execute a duty ratio limit program RPMLET.

[0044] In step S107, a duty ratio limit program RPMLET is executed. In the duty ratio limit program RPMLET, a duty ratio modulation difference is set by the duty ratio setting circuit 1012 of the control circuit 101. The duty ratio modulation instruction circuit 1013 of the control circuit 101 instructs the drive circuit 102 to modulate the duty ratio difference between every two waveforms among the subsequent generated multiple waveforms in the conduction time signal to be equal to a duty ratio modulation difference.

[0045] A duty ratio modulation difference set in step S107 is smaller than an initial duty ratio difference set in step S105. Therefore, compared with the conduction time signal generated in step S105, the duty ratio DYOUT of the conduction time signal generated in step S107 also gradually increases to the target duty ratio DYTG more slowly.

[0046] As a result, when the drive circuit 102 uses the conduction time signal generated in step S107 with a duty ratio difference equal to the duty ratio modulation difference to drive the output stage circuit 103 to operate and then drive the motor MT, the operating speed of the motor MT gradually increases from the initial speed to the target speed more slowly.

[0047] In step S108, the target limit comparison circuit 1011 of the control circuit 101 determines whether the rotational speed RPM of the motor MT is greater than or equal to a rotational speed limit value RPMLT (received from an external target limit circuit). If the rotational speed RPM of the motor MT is greater than or equal to a rotational speed limit value RPMLT, step S109 is executed. On the contrary, if the rotational speed RPM of the motor MT is not greater than a rotational speed limit value RPMLT, step S110 is executed.

[0048] In step S109, when the rotational speed RPM of the motor MT driven by the motor driver 100 according to the duty ratio of the waveforms generated within a time interval in the conduction time signal is greater than or equal to a rotational speed limit value RPMLT, the duty ratio modulation instruction circuit 1013 of the control circuit 101 in the motor driver 100 instructs the drive circuit 102 to reduce the duty ratio DYOUT of one or more waveforms generated in the next time interval in the conduction time signal, as Figure 4 shown, by subtracting a duty ratio modulation value DYST from the duty ratio DYOUT of the waveform of the conduction time signal.

[0049] In step S110, the target limit comparison circuit 1011 of the control circuit 101 determines whether the duty ratio DYOUT of the waveform currently used to drive the motor in the conduction time signal is equal to the target duty ratio DYTG obtained in step S102.

[0050] When the duty ratio DYOUT of the waveform currently used to drive the motor in the conduction time signal is equal to the target duty ratio DYTG, step S111 is executed. Conversely, when the duty ratio DYOUT of the waveform currently used to drive the motor in the conduction time signal is not equal to the target duty ratio DYTG, step S112 is executed.

[0051] In step S111, the target limit comparison circuit 1011 of the control circuit 101 determines that the conduction time signal is not further modulated.

[0052] In step S112, the target limit comparison circuit 1011 of the control circuit 101 determines whether the duty ratio DYOUT of the waveform currently used to drive the motor in the conduction time signal is greater than the target duty ratio DYTG obtained in step S102.

[0053] When the duty ratio DYOUT of the waveform currently used to drive the motor in the conduction time signal is greater than the target duty ratio DYTG, step S113 is executed. Conversely, when the duty ratio DYOUT of the waveform currently used to drive the motor in the conduction time signal is not greater than the target duty ratio DYTG, step S114 is executed.

[0054] In step S113, the target limit comparison circuit 1011 of the control circuit 101 determines to reduce the duty ratio of each subsequent waveform used to drive the motor. The duty ratio setting circuit 1012 of the control circuit 101 sets a duty ratio modulation value DYST. The duty ratio modulation instruction circuit 1013 of the control circuit 101 instructs the drive circuit 102 to subtract a duty ratio modulation value DYST from the duty ratio DYOUT of each subsequent or specified waveform of the conduction time signal.

[0055] In step S114, the target limit comparison circuit 1011 of the control circuit 101 determines to increase the duty ratio of each subsequent waveform used to drive the motor. The duty ratio setting circuit 1012 of the control circuit 101 sets a duty ratio modulation value DYST. The duty ratio modulation instruction circuit 1013 of the control circuit 101 instructs the drive circuit 102 to add a duty ratio modulation value DYST to the duty ratio DYOUT of each subsequent or specified duty ratio.

[0056] Please refer to Figure 5 , which is a circuit diagram of the output stage circuit, drive circuit, and single-phase motor of the motor speed control system with a duty ratio variable modulation mechanism according to the fourth embodiment of the present invention.

[0057] As Figure 2 and Figure 3 shown, the motor MT driven by the motor driver 100 of the motor speed control system of the present invention can be a single-phase motor as Figure 5 shown.

[0058] When the motor MT driven by the motor driver 100 is a single-phase motor, the output stage circuit of the motor driver of the motor speed regulation system of the present invention (for example Figure 2 and Figure 3 The output stage circuit 103 shown) may include a first high-side switch H1, a first low-side switch L1, a second high-side switch H2, and a second low-side switch L2.

[0059] A first end of the first high-side switch H1 is coupled to a shared voltage VCC. A first end of the first low-side switch L1 is connected to a second end of the first high-side switch H1. A second end of the first low-side switch L1 is grounded. A node between the first end of the first low-side switch L1 and the second end of the first high-side switch H1 is connected to a first end OUT1 of the motor MT.

[0060] A first end of the second high-side switch H2 is coupled to the shared voltage VCC. A first end of the second low-side switch L2 is connected to a second end of the second high-side switch H2. A second end of the second low-side switch L2 is grounded. A node between the first end of the second low-side switch L2 and the second end of the second high-side switch H2 is connected to a second end OUT2 of the motor MT.

[0061] A control end of the first high-side switch H1, a control end of the first low-side switch L1, a control end of the second high-side switch H2, and a control end of the second low-side switch L2 are connected to an output end of the drive circuit 102.

[0062] The drive circuit 102 outputs a plurality of conduction time signals to the control end of the first high-side switch H1, the control end of the first low-side switch L1, the control end of the second high-side switch H2, and the control end of the second low-side switch L2 respectively according to a plurality of control signals received from the control circuit 101.

[0063] For example, as Figure 5 shown, the first high-side switch H1 and the second high-side switch H2 are turned on during the working cycle of the received conduction time signal and turned off during the non-working cycle. As Figure 5 shown, the first low-side switch L1 and the second low-side switch L2 are turned on during the non-working cycle of the received conduction time signal and turned off during the working cycle.

[0064] Please refer to Figure 6 , which is a circuit diagram of the output stage circuit and the drive circuit of the motor speed regulation system with a duty ratio variable modulation mechanism and a three-phase motor according to the fifth embodiment of the present invention.

[0065] As Figure 2 and Figure 3 shown, the motor MT driven by the motor driver 100 of the motor speed regulation system of the present invention can be a three-phase motor as Figure 6 shown.

[0066] When the motor MT driven by the motor driver 100 is a single-phase motor, the output stage circuit of the motor driver of the motor speed regulation system of the present invention (for example Figure 2 and Figure 3 the output stage circuit 103 shown) may include a first high-side switch H1, a first low-side switch L1, a second high-side switch H2, a second low-side switch L2, a third high-side switch H3, and a third low-side switch L3.

[0067] The configurations of the first high-side switch H1, the first low-side switch L1, the second high-side switch H2, and the second low-side switch L2 are as described above and will not be elaborated here.

[0068] The first end of the third high-side switch H3 is coupled to the shared voltage VCC. The first end of the third low-side switch L3 is connected to the second end of the third high-side switch H3. The second end of the third low-side switch L3 is grounded. The node between the first end of the third low-side switch L3 and the second end of the third high-side switch H3 is connected to the third end OUT3 of the motor MT.

[0069] The first end OUT1, the second end OUT2, and the third end OUT3 of the motor MT may be the U-phase terminal, the V-phase terminal, and the W-phase terminal of a three-phase motor, respectively.

[0070] The control terminals of the first high-side switch H1, the first low-side switch L1, the second high-side switch H2, the second low-side switch L2, the third high-side switch H3, and the third low-side switch L3 are connected to the output terminal of the drive circuit 102.

[0071] The drive circuit 102 outputs a plurality of conduction time signals to the control terminals of the first high-side switch H1, the first low-side switch L1, the second high-side switch H2, the second low-side switch L2, the third high-side switch H3, and the third low-side switch L3 respectively according to a plurality of control signals received from the control circuit 101.

[0072] For example, as Figure 6 shown, the third high-side switch H3 is turned on during the working cycle of the received conduction time signal and turned off during the non-working cycle. As Figure 6 shown, the third low-side switch L3 is turned on during the non-working cycle of the received conduction time signal and turned off during the working cycle.

[0073] Please refer to Figure 7 , which is a timing diagram of the motor speed regulation system with a duty cycle variable modulation mechanism according to the sixth embodiment of the present invention entering the speed limit state.

[0074] As Figure 3The target limit comparison circuit 1011 of the control circuit 101 of the motor speed regulation system of the present invention as shown may include the code of the target duty ratio for a target duty ratio command DYTAG received from an external target limit circuit. For example, Figure 7 As shown, within a time interval, the code DYCD8d127 representing that the target duty ratio is equal to a first specified target duty ratio is received, and within the next time interval, the code DYCD8d255 representing that the target duty ratio is equal to a second specified target duty ratio is received.

[0075] The target limit comparison circuit 1011 of the control circuit 101 may store a look-up table listing multiple target duty ratios corresponding to multiple codes respectively, and may look up the target duty ratio (%) corresponding to the code of a target duty ratio specified by a target duty ratio command DYTAG from the look-up table.

[0076] The drive circuit 102 of the motor speed regulation system of the present invention may feedback the duty ratio DYOUT of the conduction time signal output to the output stage circuit 103 successively within multiple time intervals, which are represented by the corresponding codes DYCD8d127, DYCD8d128, DYCD8d129, …, DYCD8d240, DYCD8d239, DYCD8d238, DYCD8d239, to the target limit comparison circuit 1011 of the control circuit 101.

[0077] Such as Figure 3 The speed limit command received by the target limit comparison circuit 1011 of the control circuit 101 of the motor speed regulation system of the present invention as shown may include the code of a speed limit value RPMLT. For example, Figure 7 The code DYCD17d10000 as shown.

[0078] The speed detector 200 may detect the speed RPM of the motor MT and output the code corresponding to the detected speed RPM of the motor MT to the target limit comparison circuit 1011 of the control circuit 101.

[0079] When the speed RPM of the motor MT indicated by the motor speed code DYCD17d10000 increases to be equal to or greater than a speed limit value RPMLT represented by the code DYCD17d10000, the target limit comparison circuit 1011 of the control circuit 101 outputs a high-level duty ratio limit indication signal RPMLET, representing the execution of a duty ratio limit program. As a result, the speed at which the duty ratio of the conduction time signal increases to the target duty ratio over time is reduced.

[0080] Please refer to Figure 8, which is a schematic diagram of the seventh embodiment of the present invention, in which the motor speed control system with a duty cycle variable modulation mechanism releases the limited-speed duty cycle modulation mode and returns to the general duty cycle control mode.

[0081] like Figure 3 The target duty cycle instruction DYTAG received by the target limit comparison circuit 1011 of the control circuit 101 of the motor speed control system of the present invention from an external target limit circuit may include a code of the target duty cycle, for example Figure 8 As shown, a code DYCD8d255 representing that the target duty cycle is equal to a first specified target duty cycle is received in a time interval, and a code DYCD8d125 representing that the target duty cycle is equal to a second specified target duty cycle is received in the next time interval.

[0082] The target limit comparison circuit 1011 of the control circuit 101 can store a lookup table, which lists multiple target duty cycles corresponding to multiple codes. The target duty cycle (%) corresponding to a target duty cycle code specified by a target duty cycle instruction DYTAG received from an external target limit circuit can be found from the lookup table.

[0083] The driving circuit 102 of the motor speed control system of the present invention can feed back the duty cycle DYOUT of the on-time signal output to the output stage circuit 103 in multiple time intervals in sequence, represented by corresponding codes DYCD8d239, DYCD8d238, DYCD8d237, DYCD8d236...DYCD8d125, to the target limit comparison circuit 1011 of the control circuit 101.

[0084] like Figure 3 The target limit comparison circuit 1011 of the control circuit 101 of the motor speed control system of the present invention receives a speed limit instruction from an external target limit circuit, which may include a code of a speed limit value RPMLT, for example Figure 8 The code shown is DYCD17d10000.

[0085] When the speed RPM of the motor MT indicated by the motor speed code DYCD17d10000 decreases to be equal to or less than a speed limit value RPMLT represented by the code DYCD17d10000, a duty cycle limit indication signal RPMLET output by the target limit comparison circuit 1011 of the control circuit 101 changes from a high level to a low level, indicating that the duty cycle limit procedure is cancelled. As a result, the duty cycle of the increase conduction time signal increases over time to the speed of the target duty cycle.

[0086] In summary, the present invention provides a motor speed regulation system with a duty cycle variable modulation mechanism. The motor speed regulation method of the present invention can be executed by the motor speed regulation system of the present invention (including a speed detector and a motor driver). In the motor speed regulation method of the present invention, a hysteresis operation is not performed to avoid restricting the speed of the motor, resulting in the inability of the motor speed to quickly reach the target speed. In the motor speed regulation method of the present invention, as the speed of the motor changes due to various conditions and environmental factors, the duty cycle of each of a plurality of waveforms of the conduction time signal for driving the motor is modulated, and the duty cycle difference between the plurality of waveforms of the conduction time signal is modulated. Therefore, in the motor speed regulation method of the present invention, the motor can be driven to operate stably.

[0087] The above-disclosed content is only the preferred feasible embodiment of the present invention, and does not limit the scope of the claims of the present invention. Therefore, all equivalent technical changes made by using the content of the specification and drawings of the present invention are included in the claims of the present invention.

Claims

1. A motor speed control system with a duty cycle variable modulation mechanism, characterized in that, The motor speed regulation system with a duty cycle variable modulation mechanism includes: A speed detector, connected to the motor and configured to detect the speed of the motor; And A motor driver, connected to the speed detector and the motor, configured to modulate the duty cycle of a plurality of waveforms sequentially generated in a conduction time signal and a duty cycle difference between each of the plurality of waveforms of the conduction time signal and the previous one or each other one according to the speed of the motor detected by the speed detector being greater than or equal to a set speed, and drive the motor according to the conduction time signal to limit the speed of the motor below the set speed.

2. The motor speed control system with a duty cycle variable modulation mechanism according to claim 1, characterized in that, The motor driver modulates the duty cycle difference of the conduction time signal to be equal to an initial duty cycle difference according to a target duty cycle indicated by a target duty cycle command, and modulates the duty cycle of the last generated one of the plurality of waveforms of the conduction time signal to be equal to the target duty cycle.

3. The motor speed control system with a duty cycle variable modulation mechanism according to claim 2, characterized in that, When the motor driver drives the motor according to one of the plurality of waveforms of the conduction time signal, the motor driver determines the relationship between the current speed of the motor and a speed limit value to decide whether to modulate the duty cycle difference between the plurality of waveforms subsequently generated in the conduction time signal.

4. The motor speed control system with a duty cycle variable modulation mechanism according to claim 3, characterized in that, When the current speed of the motor is not greater than the speed limit value, the motor driver maintains each duty cycle difference between the plurality of waveforms subsequently generated in the conduction time signal equal to the initial duty cycle difference.

5. The motor speed control system with a duty cycle variable modulation mechanism according to claim 4, characterized in that, When the current speed of the motor is greater than or equal to the speed limit value, the motor driver sets the duty cycle difference between the plurality of waveforms subsequently generated in the conduction time signal equal to a duty cycle modulation difference, where the duty cycle modulation difference is less than the initial duty cycle difference.

6. The motor speed control system with a duty cycle variable modulation mechanism according to claim 5, characterized in that, When the motor driver drives the motor according to the conduction time signal with the duty cycle difference equal to the duty cycle modulation difference, the speed detector detects the speed of the motor.

7. The motor speed control system with a duty cycle variable modulation mechanism according to claim 6, characterized in that, When the speed of the motor driven by the conduction time signal with the duty cycle difference equal to the duty cycle modulation difference is greater than or equal to the speed limit value, the motor driver reduces the duty cycle of each of the waveforms subsequently generated in the conduction time signal.

8. The motor speed control system with a duty cycle variable modulation mechanism according to claim 7, characterized in that, When the speed of the motor driven by the conduction time signal with the duty cycle difference equal to the duty cycle modulation difference is not greater than the speed limit value, the motor driver determines whether the duty cycle of the waveform currently used to drive the motor in the conduction time signal is equal to a target duty cycle.

9. The motor speed control system with a duty cycle variable modulation mechanism according to claim 8, characterized in that, When the duty cycle of the waveform currently used to drive the motor in the conduction time signal is equal to the target duty cycle, the motor driver does not further modulate the conduction time signal.

10. The motor speed control system with a duty cycle variable modulation mechanism according to claim 9, characterized in that, When the duty ratio of the waveform currently used to drive the motor in the conduction time signal is not equal to the target duty ratio, the motor driver determines whether the duty ratio of the waveform currently used to drive the motor in the conduction time signal is greater than the target duty ratio.

11. The motor speed control system with a duty cycle variable modulation mechanism according to claim 10, characterized in that, When the duty ratio of the waveform currently used to drive the motor in the conduction time signal is greater than the target duty ratio, the motor driver reduces the duty ratio of each subsequent waveform used to drive the motor.

12. The motor speed control system with a duty cycle variable modulation mechanism according to claim 11, characterized in that, When the duty ratio of the waveform currently used to drive the motor in the conduction time signal is not greater than the target duty ratio, the motor driver increases the duty ratio of each subsequent waveform used to drive the motor.

13. The motor speed control system with a duty cycle variable modulation mechanism according to claim 1, characterized in that, The motor driver includes: A control circuit, connected to the rotational speed detector, configured to set the duty ratio of each of the multiple waveforms of the conduction time signal according to the rotational speed of the motor detected by the rotational speed detector, and set the duty ratio difference between the duty ratio of each of the multiple waveforms of the conduction time signal and the duty ratio of the previous one or each other one, and accordingly output a control signal; A drive circuit, connected to the control circuit, configured to output the conduction time signal according to the control signal received from the control circuit; And An output stage circuit, connected to the motor, configured to operate according to the conduction time signal received from the drive circuit to drive the motor.

14. The motor speed regulation system with a duty cycle variable modulation mechanism according to claim 13, characterized in that, The above-described motor speed regulation system with a duty ratio variable modulation mechanism further includes: A rotor position detection circuit, provided in the motor, connected to the control circuit, configured to detect the position of the rotor of the motor to output a rotor position detection signal, and the control circuit controls the drive circuit to drive the motor according to the rotor position detection signal.

15. The motor speed regulation system with a duty cycle variable modulation mechanism according to claim 14, characterized in that, The rotational speed detector is connected to the rotor position detection circuit, configured to judge the rotational speed of the motor according to the rotor position detection signal.

16. The motor speed regulation system with a duty cycle variable modulation mechanism according to claim 1, characterized in that, The motor is a single-phase motor.

17. The motor speed regulation system with a duty cycle variable modulation mechanism according to claim 1, characterized in that, The motor is a three-phase motor.

18. A method for regulating the speed of a motor, characterized in that, The above-described motor speed regulation method with a duty ratio variable modulation mechanism includes the following steps: (a) Using a motor driver to drive a motor to operate according to a conduction time signal; (b) Using the motor driver to receive a target duty ratio command; (c) Using the motor driver to set the duty ratio of the last generated one of the multiple waveforms of the conduction time signal to be equal to a target duty ratio specified by the target duty ratio command; (d) Using a rotational speed detector to detect the rotational speed of the motor; (e) Using the motor driver to judge whether the rotational speed of the motor is greater than or equal to a rotational speed limit value. If not, sequentially execute steps (f) to (g) and then execute step (l). If so, sequentially execute steps (h) to (j); (f) Using the motor driver to modulate the duty ratio difference between each of the multiple waveforms of the conduction time signal in each time interval and each of the waveforms in the next time interval to be equal to an initial duty ratio difference; (g) Using the motor driver, driving the motor according to the conduction time signal having the duty cycle difference equal to the initial duty cycle difference; (h) Using the motor driver, setting the duty cycle difference between the plurality of waveforms subsequently generated in the conduction time signal to be equal to a duty cycle modulation difference, wherein the duty cycle modulation difference is less than the initial duty cycle difference; (i) Using the motor driver, driving the motor according to the conduction time signal having the duty cycle difference equal to the duty cycle modulation difference; (j) Using the motor driver, determining whether the rotational speed of the motor is greater than or equal to the speed limit value, if so, performing step (k), if not, performing step (l); (k) Using the motor driver, reducing the duty cycle of each of the waveforms subsequently generated in the conduction time signal for driving the motor; (l) Using the motor driver, determining whether the duty cycle of the waveform currently used to drive the motor in the conduction time signal is equal to a target duty cycle, if so, not performing step (m) and not further modulating the conduction time signal, if not, performing step (m); and (m) Using the motor driver, determining whether the duty cycle of the waveform currently used to drive the motor in the conduction time signal is greater than the target duty cycle, if so, reducing the duty cycle of each of the waveforms subsequently used to drive the motor, if not, increasing the duty cycle of each of the waveforms subsequently used to drive the motor.

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