Motor driver with phase automatic switching mechanism

Abstract

The present application discloses a motor driver with automatic phase switching mechanism. After starting a three-phase motor, a back electromotive force detection circuit starts to detect back electromotive force signals of each phase of the three-phase motor. A drive waveform generation circuit acquires a plurality of first wave segments from a plurality of first wave patterns of a first wave pattern signal as a plurality of first wave segments of a first waveform signal according to the back electromotive force signals. A motor control circuit controls a motor drive circuit to drive the three-phase motor to operate normally according to the first waveform signal.

Description

Technical Field

[0001] This invention relates to motors, and more particularly to a motor driver with an automatic phase switching mechanism. Background Technology

[0002] In electronic devices, fan motors are used to cool heat-generating components such as processors. During the cooling process, real-time data from the motor's circuitry is crucial for accurately controlling its speed and ensuring optimal cooling performance. However, current motor control circuits cannot quickly drive the motor to normal operation and only produce low-noise operation. Summary of the Invention

[0003] The technical problem to be solved by this invention is to provide a motor driver with an automatic phase switching mechanism, applicable to three-phase motors, addressing the shortcomings of existing technologies. The driver includes a motor control circuit, a motor drive circuit, a back EMF detection circuit, a band pattern storage circuit, and a drive waveform generation circuit. The motor control circuit is configured to output a start control signal and a normal operation control signal. The motor drive circuit is connected to the motor control circuit. The motor drive circuit is configured to output a motor start signal to the three-phase motor based on the start control signal to start the three-phase motor. After starting the three-phase motor, it outputs a normal operation drive signal to the three-phase motor based on the normal operation control signal to drive the three-phase motor to operate normally. The back EMF detection circuit is connected to the three-phase motor. After starting the three-phase motor, the back EMF detection circuit is configured to detect the voltage level of the back EMF signal of each phase of the three-phase motor and output a back EMF detection signal. The band pattern storage circuit is configured to store a first band pattern signal. The first band pattern signal has multiple first band patterns of multiple first waveform patterns. The drive waveform generation circuit is connected to the back EMF detection circuit, the band pattern storage circuit, and the motor control circuit. The drive waveform generation circuit is configured to acquire multiple first bands as first waveform signals from multiple first band patterns based on the back EMF detection signal, and outputs the first waveform signal. Then, the motor control circuit outputs a normal operation control signal based on the first waveform signal.

[0004] In this embodiment, the back EMF detection circuit detects multiple waveforms of the back EMF signal of each phase of the three-phase motor, and at each zero-crossing point of the first waveform appearing after the start of detection, where the signal transitions from a high voltage level to a low voltage level and from a low voltage level to a high voltage level, to output a back EMF detection signal. The zero-crossing point is the time point at which the back EMF signal reaches zero.

[0005] In this embodiment, the back EMF detection circuit detects a zero-crossing point where the waveforms following the first waveform of the back EMF signal of each phase of the three-phase motor transition from a low voltage level to a high voltage level, and outputs a back EMF detection signal. The zero-crossing point is the time point at which the back EMF signal reaches zero.

[0006] In this embodiment, the driving waveform generation circuit determines which first-band patterns to acquire based on the zero-crossing point where the back EMF signal transitions from a low voltage level to a high voltage level, as indicated by the back EMF detection signal. The zero-crossing point is the time point at which the back EMF signal reaches zero.

[0007] In this embodiment, the driving waveform generation circuit determines which first-band patterns to acquire based on the zero-crossing point where the back EMF signal transitions from a high voltage level to a low voltage level, as indicated by the back EMF detection signal. The zero-crossing point is the time point at which the back EMF signal reaches zero.

[0008] In an embodiment, when a voltage of the back electromotive force signal is greater than zero, the driving waveform generation circuit obtains multiple first band patterns from multiple first band patterns of the first band pattern signal as multiple first bands of the first waveform signal output within a time after the voltage of the back electromotive force signal drops to zero.

[0009] In an embodiment, when a voltage of the back electromotive force signal is less than zero, the driving waveform generation circuit obtains multiple first band patterns from multiple first band patterns of the first band pattern signal as multiple first bands of the first waveform signal output within a time after the voltage of the back electromotive force signal rises to zero.

[0010] In this embodiment, the back EMF detection circuit includes a comparator circuit. A first input terminal of the comparator circuit is connected to and receives a back EMF signal from the three-phase motor. A second input terminal of the comparator circuit is coupled to a reference voltage. The comparator circuit compares the voltage of the back EMF signal with the reference voltage to output a back EMF detection signal.

[0011] In this embodiment, the reference voltage is half the sum of the peak and trough values ​​of the back electromotive force signal waveform.

[0012] In one embodiment, the drive waveform generation circuit compares multiple values ​​of a first waveform signal with those of a second waveform signal to output a drive waveform signal. The motor control circuit adjusts the normal operation control signal output to the three-phase motor drive circuit based on the drive waveform signal.

[0013] In an embodiment, the multiple waveforms of the second waveform signal include multiple triangular wave waveforms, multiple sawtooth wave waveforms, or combinations thereof.

[0014] In an embodiment, the multiple waveforms of the first waveform signal include multiple sine wave waveforms, multiple third harmonic waveforms, or combinations thereof.

[0015] As described above, the present invention provides a motor driver with an automatic phase switching mechanism, which has the following characteristics:

[0016] 1. After the motor starts, the zero-crossing point of the back electromotive force signal from high voltage level to low voltage level and from low voltage level to high voltage level can be detected to determine the waveform of the first waveform signal, so as to quickly drive the three-phase motor to operate normally.

[0017] 2. If the fan is used in a handheld device and is in motion or for other reasons, causing the phase of the fan's three-phase motor to be different from expected, the phase of the three-phase motor can be automatically changed to make the three-phase motor operate normally.

[0018] 3. Regardless of the phase of the back electromotive force, it can be detected, thus shortening the detection time and enabling the three-phase motor to operate normally earlier, thereby improving vibration and noise.

[0019] 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 drawings provided are for reference and illustration only and are not intended to limit the present invention. Attached Figure Description

[0020] Figure 1 This is a block diagram of a motor driver with an automatic phase switching mechanism according to an embodiment of the present invention.

[0021] Figure 2 The present invention relates to a motor drive circuit for a motor driver with an automatic phase switching mechanism and a circuit diagram of a three-phase motor.

[0022] Figure 3 The waveform diagram shows the signal of a motor driver with an automatic phase switching mechanism according to an embodiment of the present invention.

[0023] Figure 4 The waveform diagram shows the signal of a motor driver with an automatic phase switching mechanism according to an embodiment of the present invention.

[0024] Figure 5 This is a circuit diagram of the back electromotive force detection circuit of a motor driver with an automatic phase switching mechanism according to an embodiment of the present invention.

[0025] Figure 6 The waveform diagram shows the signal when the phase and back electromotive force of a three-phase motor driven by an embodiment of the present invention and a conventional motor driver are the same.

[0026] Figure 7The waveform diagram shows the signal when the phase and back electromotive force of the three-phase motor driven by the motor driver in this embodiment of the invention are different.

[0027] Figure 8 Waveform diagram of the signal when the phase and back electromotive force of a three-phase motor driven by a conventional motor driver are different. Detailed Implementation

[0028] The following specific embodiments illustrate the implementation of the present invention. Those skilled in the art can understand the advantages and effects of the present invention from the content disclosed in this specification. The present invention can be implemented or applied through other different specific embodiments, and various details in this specification can also be modified and changed based on different viewpoints and applications without departing from the concept of the present invention. Furthermore, the accompanying drawings of the present invention are for simple illustrative purposes only and are not depictions of actual dimensions, as stated in advance. The following embodiments will further describe the relevant technical content of the present invention in detail, but the disclosed content is not intended to limit the scope of protection of the present invention. In addition, the term "or" as used herein may, depending on the actual situation, include any combination of any one or more of the associated listed items.

[0029] Please see Figures 1 to 4 ,in Figure 1 This is a block diagram of a motor driver with an automatic phase switching mechanism according to an embodiment of the present invention. Figure 2 The present invention relates to a motor drive circuit and a circuit diagram of a motor driver with an automatic phase switching mechanism according to an embodiment of the present invention. Figure 3 and Figure 4 The waveform diagram shows the signal of a motor driver with an automatic phase switching mechanism according to an embodiment of the present invention.

[0030] The motor driver of this invention may include, as in the following embodiments: Figure 1 The circuit shown includes a back EMF detection circuit 10, a band pattern storage circuit 20, a drive waveform generation circuit 30, a motor control circuit 40, and a motor drive circuit 50.

[0031] like Figure 1 As shown, the drive waveform generation circuit 30 can be connected to the back EMF detection circuit 10, the band pattern storage circuit 20, and the motor control circuit 40. The motor drive circuit 50 can be connected to the motor control circuit 40 and the three-phase motor MT.

[0032] The motor drive circuit 50 may include multiple switching components, such as Figure 2 The first upper bridge switch HD1, the second upper bridge switch HD2, the third upper bridge switch HD3, the first lower bridge switch LD1, the second lower bridge switch LD2, and the third lower bridge switch LD3 are shown. The control terminals of each switch assembly of the motor drive circuit 50 can be connected to the output terminals of the motor control circuit 40.

[0033] The first terminal of the first upper bridge switch HD1 can be coupled to the first input voltage VINU. The second terminal of the first upper bridge switch HD1 can be connected to the first terminal of the first lower bridge switch LD1. The second terminal of the first lower bridge switch LD1 can be coupled to the first reference potential VGU, for example, ground. The node NU between the second terminal of the first upper bridge switch HD1 and the first terminal of the first lower bridge switch LD1 can be connected to the first terminal of the first coil CLU of the three-phase motor MT. The second terminal of the first coil CLU can be connected to the shared terminal COM of the three-phase motor MT.

[0034] The first terminal of the second upper bridge switch HD2 can be coupled to the second input voltage VINV. The second terminal of the second upper bridge switch HD2 can be connected to the first terminal of the second lower bridge switch LD2. The second terminal of the second lower bridge switch LD2 can be coupled to the second reference potential VGV, for example, ground. The node NV between the second terminal of the second upper bridge switch HD2 and the first terminal of the second lower bridge switch LD2 can be connected to the first terminal of the second coil CLV of the three-phase motor MT. The second terminal of the second coil CLV can be connected to the shared terminal COM of the three-phase motor MT.

[0035] The first terminal of the third upper bridge switch HD3 can be coupled to the third input voltage VINW. The second terminal of the third upper bridge switch HD3 can be connected to the first terminal of the third lower bridge switch LD3. The second terminal of the third lower bridge switch LD3 can be coupled to the third reference potential VGW, for example, ground. The node NW between the second terminal of the third upper bridge switch HD3 and the first terminal of the third lower bridge switch LD3 can be connected to the first terminal of the third coil CLW of the three-phase motor MT. The second terminal of the third coil CLW can be connected to the shared terminal COM of the three-phase motor MT.

[0036] When the motor driver wants to start the three-phase motor MT, the motor control circuit 40 can, as follows: Figure 3 During a given start-up time interval, a start-up control signal is output to the control terminal of any switching component in the motor drive circuit 50. The motor drive circuit 50 can output a start-up control signal as shown in the figure, based on the start-up control signal received from the motor control circuit 40. Figure 3 The motor start signal SPS is sent to the three-phase motor MT to start the three-phase motor MT.

[0037] After the three-phase motor MT is started, the back EMF detection circuit 10 can detect, for example... Figure 2 One or more of the back electromotive force (EMF) signals of the U phase (BEMFU) (EUS), the V phase (BEMFV) (EVS), and the W phase (BEMFW) (EWS) of the three-phase motor MT are used to output a back EMF detection signal.

[0038] The band pattern storage circuit 20 can store a first band pattern signal. The first band pattern signal can have multiple first band patterns of multiple first waveforms. Each waveform has multiple first band patterns. The multiple first waveforms can include multiple sine wave waveforms, multiple third harmonic waveforms, or combinations thereof, which are only examples and are not limited to this invention.

[0039] The driving waveform generation circuit 30 can obtain multiple first band patterns from multiple first band patterns provided by the band pattern storage circuit 20 based on the back EMF detection signal received from the back EMF detection circuit 10, in order to determine the first waveform signal (e.g., Figure 3 The first waveform signal NRS shown is as follows: Figure 4 The first waveform signal (WS21 or WS22) shown is a first waveform signal consisting of multiple complete (or incomplete) first waveform segments, and the first waveform signal is output to the motor control circuit 40.

[0040] After starting the three-phase motor MT within the start-up time interval, the motor control circuit 40 can determine the first waveform signal (e.g., Figure 3 The first waveform signal NRS shown is or as follows Figure 4 The first waveform signal (WS21 or WS22) shown is used to output a normal operation control signal to the motor drive circuit 50. The motor drive circuit 50 can output a normal operation drive signal to the three-phase motor MT according to the normal operation control signal, so as to drive the three-phase motor MT to operate normally within the normal operation time range.

[0041] If needed, the drive waveform generation circuit 30 can compare the first waveform signal (e.g., Figure 3 The first waveform signal NRS shown is or as follows Figure 4 The first waveform signal WS21 or WS22 shown and the second waveform signal (e.g.) Figure 4 Multiple values ​​of the second waveform signal WS1 shown are used to output a drive waveform signal (e.g., Figure 4 The driving waveform signal WLS is shown.

[0042] For example, the first waveform of the first waveform signal includes multiple sine wave waveforms, multiple third harmonic waveforms, or combinations thereof, and the second waveform signal includes multiple triangular wave waveforms, multiple sawtooth wave waveforms, or combinations thereof.

[0043] After starting the three-phase motor MT within the start-up time interval, the motor control circuit 40 can determine the appropriate control signal based on the drive waveform signal (e.g., ...). Figure 4The drive waveform signal WLS shown is used to output a normal operation control signal to the control terminal of the third upper bridge switch HD3 connected to the third coil CLW of the W phase of the three-phase motor MT in the motor drive circuit 50. The motor drive circuit 50 can output a normal operation drive signal (e.g., according to the normal operation control signal) based on the normal operation control signal. Figure 4 The normal operation drive signal (WLS) shown is sent to the three-phase motor MT to drive the three-phase motor MT to operate normally within the normal operation time range. In addition, the motor drive circuit 50 can output other normal operation drive signals ULS and VLS to the three-phase motor MT.

[0044] It is worth noting that in order to quickly drive the three-phase motor MT to normal operation after starting it, the above-mentioned tests are necessary. Figure 2 The back electromotive force (EMF) of the U phase, BEMFU, the back EMF of the V phase, BEMFV, and the back EMF of the W phase of the three-phase motor MT are shown.

[0045] However, when the back EMF detection circuit 10 detects any of the back EMF signals EUS, EVS, or EWS of the three-phase motor MT, the motor control circuit 40 needs to shut down the switching components of the motor drive circuit 50. For example, the motor control circuit 40 shuts down the third upper bridge switch HD3 and the third lower bridge switch LD3 in the motor drive circuit 50, which are connected to one end of the W phase of the three-phase motor MT, to interrupt the current flow through the coil of the W phase of the three-phase motor MT for a period of time, causing the three-phase motor MT of the fan to generate noise. At this time, the back EMF detection circuit 10 can detect the back EMF signal EWS of the W phase of the three-phase motor MT.

[0046] The number of times the back EMF detection circuit 10 detects the back EMF signals EUS, EVS, and EWS is proportional to the noise level. Therefore, the number of times the back EMF signals EUS, EVS, and EWS are detected depends on the degree of normal operation of the precisely driven three-phase motor MT and the acceptable noise level.

[0047] For example, the back EMF detection circuit 10 detects only the voltage level of the first waveform of the back EMF signal BEMFS after detection begins or the motor MT starts, in order to output a back EMF detection signal. If necessary, after detecting the first waveform among multiple waveforms of the back EMF signal BEMFS, the back EMF detection circuit 10 can further detect the voltage levels of one or more subsequent waveforms of the back EMF signal BEMFS, in order to output a back EMF detection signal.

[0048] In this embodiment, the back electromotive force detection circuit 10 can detect the zero-crossing point where the first waveform of the back electromotive force signal BEMFS of each phase of the three-phase motor MT changes from a low voltage level to a high voltage level, and can detect the zero-crossing point where this first waveform changes from a high voltage level to a low voltage level, so as to output the back electromotive force detection signal.

[0049] That is, the back EMF detection circuit 10 can detect whether the first waveform of the back EMF signal BEMFS reaches a zero-crossing point (from a low voltage level to a high voltage level) or a zero-crossing point (from a high voltage level to a low voltage level) first after the start of detection or the start of the motor MT, and output a back EMF detection signal. In this embodiment, the zero-crossing point is the time point when the voltage of the back EMF signal BEMFS reaches zero.

[0050] like Figure 3 As shown, after a startup time interval ends, the back EMF detection circuit 10 begins to detect the back EMF signal BEMFS of each phase of the three-phase motor MT. The back EMF detection circuit 10 first detects the zero-crossing point where the first waveform of the multiple waveforms of the back EMF signal BEMFS transitions from a low voltage level to a high voltage level.

[0051] After the back EMF detection circuit 10 detects the zero-crossing point where the first waveform of the back EMF signal BEMFS transitions from a low voltage level to a high voltage level and the zero-crossing point where it transitions from a high voltage level to a low voltage level, the back EMF detection circuit 10 can detect the zero-crossing points where other waveforms appearing after the first waveform of the back EMF signal BEMFS of each phase of the three-phase motor MT transition from a low voltage level to a high voltage level, so as to output a back EMF detection signal.

[0052] If necessary, the back EMF detection circuit 10 can also detect the zero-crossing point where other waveforms appear after the first waveform of the back EMF signal BEMFS change from the high voltage level to the low voltage level, so as to output a back EMF detection signal.

[0053] The drive waveform generation circuit 30 can acquire multiple first bands from multiple first band patterns of the first band pattern signal based on the back electromotive force signal BEMFS, and use these as multiple first bands of the first waveform signal to connect the waveform of a motor start signal. The first occurrence of the multiple first waveforms of the first waveform signal may be a complete or only part of a sine wave waveform or a third harmonic waveform. The first waveform of the first waveform signal depends on the time point when the back electromotive force signal BEMFS reaches zero and the change in the voltage level of the back electromotive force signal BEMFS.

[0054] When the voltage of the back electromotive force signal BEMFS is greater than zero, the drive waveform generation circuit 30 can obtain multiple first-band patterns from multiple first-band patterns of the first-band pattern signal, as multiple first-band patterns of the first waveform signal output within a time after the voltage of the back electromotive force signal BEMFS drops to zero, and connect them to the waveform of a motor start signal.

[0055] When the voltage of the back electromotive force signal BEMFS is less than zero, the drive waveform generation circuit 30 can obtain multiple first-band patterns from multiple first-band patterns of the first-band pattern signal, as multiple first-band patterns of the first waveform signal output within a time after the voltage of the back electromotive force signal BEMFS rises to zero, and connect them to the waveform of a motor start signal.

[0056] Please see Figure 1 and Figure 5 ,in Figure 1 This is a block diagram of a motor driver with an automatic phase switching mechanism according to an embodiment of the present invention. Figure 5 This is a circuit diagram of the back electromotive force detection circuit of a motor driver with an automatic phase switching mechanism according to an embodiment of the present invention.

[0057] like Figure 1 The back EMF detection circuit 10 shown may include a comparator circuit. The comparator circuit may include one or more comparators, for example, including... Figure 5 The first comparator CMP is shown. In fact, the comparison circuit of the back EMF detection circuit 10 may also include a second comparator and a third comparator.

[0058] The first comparator CMP, the second comparator, and the third comparator can be used to detect the back electromotive force signal of the U phase of the three-phase motor MT (e.g., Figure 2 The back electromotive force signal EUS shown), the back electromotive force signal of phase V (e.g.) Figure 2 The back electromotive force signal (EVS) shown and the back electromotive force signal of phase W (e.g., Figure 2 The back electromotive force signal EWS is shown.

[0059] The first input of the first comparator CMP can be connected to the second terminal of the first coil CLU of the U phase of the three-phase motor MT to receive the back electromotive force (EMF) signal EUS. The first input of the second comparator can be connected to the second terminal of the second coil CLV of the V phase of the three-phase motor MT to receive the back EMF signal EVS. The first input of the third comparator can be connected to the second terminal of the third coil CLW of the W phase of the three-phase motor MT to receive the back EMF signal EWS.

[0060] The second input of the first comparator CMP can be coupled to a first reference voltage Vref. The second input of the second comparator can be coupled to a second reference voltage. The second input of the third comparator can be coupled to a third reference voltage.

[0061] The first comparator CMP compares the voltage of the back electromotive force signal EUS with a first reference voltage Vref to output a back electromotive force detection signal to the drive waveform generation circuit 30. This first reference voltage can be half the sum of the peak and trough values ​​of the back electromotive force signal EUS, but the present invention is not limited thereto.

[0062] The second comparator compares the voltage of the back electromotive force signal EVS with a second reference voltage to output a back electromotive force detection signal to the drive waveform generation circuit 30. This second reference voltage can be half the sum of the peak and trough values ​​of the back electromotive force signal EUV, but the present invention is not limited thereto.

[0063] The third comparator compares the voltage of the back electromotive force signal EWS with a third reference voltage to output a back electromotive force detection signal to the drive waveform generation circuit 30. This third reference voltage can be half the sum of the peak and trough values ​​of the back electromotive force signal EUW, but the present invention is not limited thereto.

[0064] Please see Figure 1 and Figures 6 to 8 ,in Figure 6 The waveform diagram of the signal when the phase and back electromotive force of the three-phase motor driven by the embodiment of the present invention and the conventional motor driver are the same; Figure 7 The waveform diagram of the signal when the phase and back electromotive force of the three-phase motor driven by the motor driver in this embodiment of the invention are different; Figure 8 Waveform diagram of the signal when the phase and back electromotive force of a three-phase motor driven by a conventional motor driver are different.

[0065] When the phase and back electromotive force (the actual position of the three-phase motor MT driven by the motor driver of this invention and the conventional motor driver are the same, such as Figure 6 As shown, after entering the normal operation time interval from the start-up time interval, the first waveform signal CU01 is output after only a short period of time to drive the three-phase motor MT.

[0066] It is worth noting that when the phase and back electromotive force of a three-phase motor MT driven by a conventional motor driver are different, then... Figure 8 As shown, during the transition from the start-up time interval to the normal operation time interval, an excessively long detection time TD0 is required before the first waveform signal CU0 for driving the motor is output, causing noise to be generated in the three-phase motor MT.

[0067] In contrast, the motor driver of this invention, after starting the three-phase motor MT, in such a way... Figure 7 Within the acquisition time TD1 shown, the voltage waveform of the back electromotive force signal BEMFS of the three-phase motor MT is acquired. Figure 7 Within the detection time TD2 shown, such as Figure 5 The first comparator CMP shown compares the voltage of the acquired back electromotive force signal BEMFS with the first reference voltage Vref to detect the zero-crossing point where the waveform of the back electromotive force signal BEMFS of the three-phase motor MT changes from a low voltage level to a high voltage level, and also detects the zero-crossing point where the waveform of the back electromotive force signal BEMFS changes from a high voltage level to a low voltage level.

[0068] It should be understood that the acquisition time TD1 is less than the detection time TD2, so as to avoid occupying the time of the first comparator CMP to perform the above comparison operation, thus affecting the zero crossing point of the back electromotive force signal BEMFS that is actually to be detected.

[0069] When the phase and back electromotive force of the three-phase motor MT driven by the motor driver of this invention are not the same, such as Figure 7 As shown, after the three-phase motor MT starts and enters the normal operating time range, a brief acquisition time TD1 is used to determine whether the voltage of the back electromotive force (BEMFS) signal is greater than or less than the first reference voltage Vref. If the voltage of the back EMF signal BEMFS is greater than the first reference voltage Vref, it can be predicted that the back EMF signal BEMFS will soon switch from a high level to a low level. Therefore, we will wait for the zero-crossing point of the back EMF signal BEMFS switching from a high level to a low level, and directly output the lower sine voltage drive waveform of the first waveform signal CU1 after the zero-crossing point appears, without waiting. Figure 8 The detection time TD0 is very long. Therefore, in this situation, at most only a shorter detection time TD2 (relative to the detection time TD0) needs to be waited. Figure 8 When the detection time TD0 is reached, the first waveform signal CU1 is output to drive the three-phase motor MT to operate normally, thereby effectively preventing the three-phase motor MT from generating noise.

[0070] Similarly, upon entering the normal operating time range, a brief acquisition time TD1 is used to determine whether the voltage of the back electromotive force (BEMFS) signal is greater than or less than the first reference voltage Vref. If the voltage of the BEMFS signal is less than the first reference voltage Vref, it can be predicted that the BEMFS signal will soon transition from a low level to a high level. Therefore, we will wait for the zero-crossing point between the low and high levels, and after the zero-crossing point appears, directly output the upper sine wave voltage drive waveform of the first waveform signal CU1, which is equivalent to... Figure 6 The situation is shown below.

[0071] To reiterate, the acquisition time TD1 is shorter than the detection time TD2. This is because the acquisition time TD1 is only used to observe whether the voltage of the back EMF signal BEMFS is greater than or less than the first reference voltage Vref. This allows us to determine whether the zero-crossing point of the back EMF signal BEMFS is transitioning from a low level to a high level, or vice versa, and thus to prepare to output the upper or lower sine wave voltage drive waveform of the first waveform signal CU1. The acquisition time TD1 for observing the level of the back EMF signal BEMFS must be shorter than the detection time TD2 for detecting the zero-crossing point of the back EMF signal BEMFS to avoid consuming the time of the first comparator CMP operation.

[0072] In summary, the present invention provides a motor driver with an automatic phase switching mechanism, which has the following characteristics:

[0073] 1. After the motor starts, the zero-crossing point of the back electromotive force signal from high voltage level to low voltage level and from low voltage level to high voltage level can be detected to determine the waveform of the first waveform signal, so as to quickly drive the three-phase motor to operate normally.

[0074] 2. If the fan is used in a handheld device and is in motion or for other reasons, causing the phase of the fan's three-phase motor to be different from expected, the phase of the three-phase motor can be automatically changed to make the three-phase motor operate normally.

[0075] 3. Regardless of the phase of the back electromotive force, it can be detected, thus shortening the detection time and enabling the three-phase motor to operate normally earlier, thereby improving vibration and noise.

[0076] The above-disclosed content is only a preferred and feasible embodiment of the present invention and is not intended to limit the claims of the present invention. Therefore, all equivalent technical changes made based on the description and drawings of the present invention are included in the claims of the present invention.

Claims

1. A motor driver with an automatic phase switching mechanism, suitable for three-phase motors, characterized in that, The motor driver with automatic phase switching mechanism includes: Motor control circuit, configured to output start control signal and normal operation control signal; A motor drive circuit, connected to the motor control circuit, is configured to output a motor start signal to the three-phase motor according to the start control signal to start the three-phase motor, and after starting the three-phase motor, output a normal operation drive signal to the three-phase motor according to the normal operation control signal to drive the three-phase motor to operate normally. A back electromotive force (EMF) detection circuit, connected to the three-phase motor, is configured to detect the voltage level of the back EMF signal of each phase of the three-phase motor after the three-phase motor is started, so as to output a back EMF detection signal. A band pattern storage circuit is configured to store a first band pattern signal, the first band pattern signal having a plurality of first waveform patterns in the first band pattern; as well as A drive waveform generation circuit is connected to the back EMF detection circuit, the band pattern storage circuit, and the motor control circuit. It is configured to acquire multiple first bands as first waveform signals from the multiple first band patterns based on the back EMF detection signal, and output the first waveform signal. Then, the motor control circuit outputs the normal operation control signal based on the first waveform signal. The back EMF detection circuit is configured to detect, among multiple waveforms of the back EMF signal of each phase of the three-phase motor, a zero-crossing point when the first waveform that appears after the start of detection transitions from a high voltage level to a low voltage level and from a low voltage level to a high voltage level, and outputs the back EMF detection signal. The zero-crossing point is the time point when the back EMF signal reaches zero.

2. The motor driver with automatic phase switching mechanism according to claim 1, characterized in that, The back EMF detection circuit detects the zero-crossing point where each of the multiple waveforms of the back EMF signal of each phase of the three-phase motor transitions from a low voltage level to a high voltage level, and outputs the back EMF detection signal.

3. The motor driver with automatic phase switching mechanism according to claim 1, characterized in that, The driving waveform generation circuit determines which first band patterns to acquire based on the zero-crossing point where the back EMF signal transitions from a low voltage level to a high voltage level, as indicated by the back EMF detection signal.

4. The motor driver with automatic phase switching mechanism according to claim 1, characterized in that, The driving waveform generation circuit determines which first band patterns to acquire based on the zero-crossing point where the back EMF signal transitions from a high voltage level to a low voltage level, as indicated by the back EMF detection signal.

5. The motor driver with automatic phase switching mechanism according to claim 1, characterized in that, When the voltage of the back electromotive force signal is greater than zero, the driving waveform generation circuit obtains multiple first band patterns from the multiple first band patterns of the first band pattern signal, as the multiple first bands of the first waveform signal output within a time after the voltage of the back electromotive force signal drops to zero.

6. The motor driver with automatic phase switching mechanism according to claim 1, characterized in that, When a voltage of the back electromotive force signal is less than zero, the driving waveform generation circuit obtains multiple first band patterns from the multiple first band patterns of the first band pattern signal, as the multiple first bands of the first waveform signal output within a time after the voltage of the back electromotive force signal rises to zero.

7. The motor driver with automatic phase switching mechanism according to claim 1, characterized in that, The back EMF detection circuit includes a comparator circuit. The first input terminal of the comparator circuit is connected to the three-phase motor and receives the back EMF signal from the three-phase motor. The second input terminal of the comparator circuit is coupled to a reference voltage. The comparator circuit compares the voltage of the back EMF signal with the reference voltage to output the back EMF detection signal.

8. The motor driver with automatic phase switching mechanism according to claim 7, characterized in that, The reference voltage is half the sum of the peak value and the trough value of one of the multiple waveforms of the back electromotive force signal.

9. The motor driver with automatic phase switching mechanism according to claim 1, characterized in that, The drive waveform generation circuit compares multiple values ​​of the first waveform signal and the second waveform signal to output a drive waveform signal, and the motor control circuit adjusts the normal operation control signal output to the motor drive circuit according to the drive waveform signal.

10. The motor driver with automatic phase switching mechanism according to claim 9, characterized in that, The second waveform signal includes multiple triangular wave waveforms, multiple sawtooth wave waveforms, or a combination of the multiple triangular wave waveforms and the multiple sawtooth wave waveforms.

11. The motor driver with automatic phase switching mechanism according to claim 1, characterized in that, The first waveform signal includes multiple sine wave waveforms, multiple third harmonic waveforms, or a combination of the multiple sine wave waveforms and the multiple third harmonic waveforms.

Images