Motor driver having automatic release protection mechanism and motor driving method thereof

Abstract

A motor driver having an automatic release protection mechanism and a motor driving method thereof is provided. The motor driver includes an output stage circuit, a motor driving circuit and a rotational speed detector circuit. The output stage circuit includes a plurality of circuit switches each including a high-side switch and a low-side switch. The motor driving circuit performs a protection process in which the low-side switch of at least one of the plurality of circuit switches is turned off. The rotational speed detector circuit detects rotational speed of a motor at a plurality of detection time points. The motor driving circuit, according to the detected rotational speed of the motor, controls or modulates an ending time point and a time length that the protection process is performed.

Description

Technical Field

[0001] This invention relates to motor drives, and more particularly to a motor drive with an automatic protection release mechanism and a motor driving method. Prior Technology

[0002] Electronic products generate heat during operation, especially in enclosed spaces or enclosures. The heat produced by these components circulates within the enclosure, heating other components and potentially causing them to overheat and break down. Therefore, electronic products must be equipped with fans to cool the circuit components.

[0003] When a conventional motor driver attempts to drastically reduce the speed of a fan motor from high to low, it first reduces the duty cycle of multiple waveforms in the on-time signal output to the upper bridge switch, while simultaneously increasing the duty cycle of multiple waveforms in the on-time signal output to the lower bridge switch. Initially, the motor speed does not immediately decrease to a low value, and due to the motor's inertia, the back electromotive force is large. Simultaneously, during the high on-time of the lower bridge switch, the reverse current continuously increases to an excessive value. As a result, once the lower bridge switch is switched to the off state, even if the upper bridge switch is not conducting, the excessive reverse current will still flow back through the parasitic diode of the upper bridge switch, causing the input capacitor or other circuit components at the input terminal of the conventional motor driver to burn out.

[0004] To avoid the aforementioned situation, traditional motor drivers keep the lower bridge switch closed when attempting to significantly reduce the motor speed from high to low, preventing the reverse current from increasing to an excessive value. However, traditional motor drivers fail to properly control the duration for which the lower bridge switch remains closed, resulting in a duration that is either too long or too short. This prevents the driver from achieving both reduced reverse current and high motor drive efficiency. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides a motor driver with an automatic protection release mechanism. The motor driver of this invention includes an output stage circuit, a motor drive circuit, and a speed detection circuit. The output stage circuit includes multiple switching circuits. Each switching circuit includes an upper bridge switch and a lower bridge switch. The first terminal of the upper bridge switch is coupled to an input voltage. The first terminal of the lower bridge switch is connected to the second terminal of the upper bridge switch. The second terminal of the lower bridge switch is grounded. The node between the second terminal of the lower bridge switch and the first terminal of the upper bridge switch is connected to one end of the motor. The motor drive circuit is connected to the control terminals of each upper bridge switch and each lower bridge switch. The motor drive circuit is configured to execute a protection program, in which at least one lower bridge switch of the switching circuit is turned off. The speed detection circuit is connected to the motor drive circuit. The speed detection circuit is configured to detect multiple speeds of the motor at multiple detection time points as multiple detected speeds. The motor drive circuit controls or modulates the end time and duration of the protection program based on the multiple detected speeds.

[0006] Furthermore, to address the shortcomings of existing technologies, this invention provides a motor driving method with an automatic protection release mechanism. This motor driving method is applicable to motors. The motor is connected to multiple switching circuits. Each switching circuit includes an upper bridge switch and a lower bridge switch. The first terminal of the upper bridge switch is coupled to an input voltage. The first terminal of the lower bridge switch is connected to the second terminal of the upper bridge switch. The second terminal of the lower bridge switch is grounded. The node between the second terminal of the lower bridge switch and the first terminal of the upper bridge switch is connected to one end of the motor. The motor driving method with an automatic protection release mechanism includes the following steps: executing a protection program, in which at least one lower bridge switch of the switching circuit is turned off; detecting multiple rotational speeds of the motor at multiple detection time points, respectively, as multiple detected rotational speeds; and controlling or adjusting the end time point and duration of the protection program execution based on the multiple detected rotational speeds.

[0007] As described above, the present invention provides a motor driver and a motor driving method with an automatic protection release mechanism. The motor driver and motor driving method of the present invention can appropriately control the end time and duration of the protection program execution, and in particular, release the protection program at an appropriate end time to achieve the effect of preventing reverse current backflow into the circuit elements at the input terminal of the motor driver of the present invention, and also to achieve high driving efficiency for the motor.

[0008] 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. Simple Explanation of the Diagram

[0009] Figure 1 is a block diagram of a motor driver with an automatic deactivation protection mechanism according to a first embodiment of the present invention.

[0010] Figure 2 is a flowchart of the steps of the motor driving method with an automatic protection release mechanism according to the first embodiment of the present invention.

[0011] Figure 3 is a block diagram of a motor driver with an automatic deactivation protection mechanism according to a second embodiment of the present invention.

[0012] Figure 4 is a block diagram of a motor driver with an automatic deactivation protection mechanism according to a third embodiment of the present invention.

[0013] Figure 5 is a flowchart of the steps of the motor drive method with an automatic protection release mechanism according to the third embodiment of the present invention.

[0014] Figure 6 is a circuit diagram of the output stage circuit of the motor driver with an automatic protection release mechanism and the motor according to the first to third embodiments of the present invention.

[0015] Figure 7 is a schematic diagram of the current flow in the protection mode of the output stage circuit of the motor driver with automatic deprotection mechanism according to the first to third embodiments of the present invention.

[0016] Figure 8 shows the waveforms of the signals generated by the motor driver and motor driving method with automatic deprotection mechanism according to the first to third embodiments of the present invention.

[0017] Figure 9 shows the waveforms of the signals generated by the motor driver and motor driving method with automatic protection release mechanism according to the first to third embodiments of the present invention. Implementation

[0018] 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" used herein should be interpreted to include, depending on the actual situation, any combination of any one or more of the associated listed items.

[0019] Please refer to Figures 1, 2, 6, and 7, where Figure 1 is a block diagram of a motor driver with an automatic protection release mechanism according to the first embodiment of the present invention, Figure 2 is a flowchart of the steps of a motor driving method with an automatic protection release mechanism according to the first embodiment of the present invention, Figure 6 is a circuit diagram of the output stage circuit and the motor of the motor driver with an automatic protection release mechanism according to the first to third embodiments of the present invention, and Figure 7 is a schematic diagram of the current flow direction of the output stage circuit of the motor driver with an automatic protection release mechanism according to the first to third embodiments of the present invention in protection mode.

[0020] As shown in Figure 1, in the first embodiment, the motor driver of the present invention includes a motor drive circuit 100, an output stage circuit 200, and a speed detection circuit 300. The motor drive circuit 100 is connected to the output stage circuit 200 and the speed detection circuit 300. The output stage circuit 200 is connected to the motor MT.

[0021] The motor driver of the present invention is applicable to the motor MT shown in FIG1, which is, for example but not limited to, the same as the three-phase motor shown in FIG6.

[0022] As shown in Figure 1, the motor driver of the present invention is applicable to performing steps S101 to S103 as shown in Figure 2 in the motor driving method of the present invention.

[0023] The output stage circuit 200 shown in Figure 1 may include multiple switching circuits as shown in Figure 6, wherein each switching circuit includes an upper bridge switch and a lower bridge switch. For example, one of the multiple switching circuits in the output stage circuit 200 includes a first upper bridge switch TH1 and a first lower bridge switch TL1, another switching circuit includes a second upper bridge switch TH2 and a second lower bridge switch TL2, and yet another switching circuit includes a third upper bridge switch TH3 and a third lower bridge switch TL3.

[0024] As shown in Figure 6, the first terminal of the first upper bridge switch TH1 is coupled to the first input voltage VINU. The first terminal of the first lower bridge switch TL1 is connected to the second terminal of the first upper bridge switch TH1. The first node NDU between the first terminal of the first lower bridge switch TL1 and the second terminal of the first upper bridge switch TH1 is connected to the first terminal of the first phase coil COILU of the first phase of the motor MT, for example, phase U. The second terminal of the first lower bridge switch TL1 is coupled to the first reference potential VGU.

[0025] The first terminal of the second upper bridge switch TH2 is coupled to the second input voltage VINV. The first terminal of the second lower bridge switch TL2 is connected to the second terminal of the second upper bridge switch TH2. The second node NDV between the first terminal of the second lower bridge switch TL2 and the second terminal of the second upper bridge switch TH2 is connected to the first terminal of the second phase coil COILV of the second phase of the motor MT, for example, phase V. The second terminal of the second lower bridge switch TL2 is coupled to the second reference potential VGV.

[0026] The first terminal of the third upper bridge switch TH3 is coupled to the third input voltage VINW. The first terminal of the third lower bridge switch TL3 is connected to the second terminal of the third upper bridge switch TH3. The third node NDW between the first terminal of the third lower bridge switch TL3 and the second terminal of the third upper bridge switch TH3 is connected to the first terminal of the third phase coil COILW of the third phase of the motor MT, for example, phase W. The second terminal of the third lower bridge switch TL3 is coupled to the third reference potential VGW.

[0027] The second terminal of the first phase coil COILU of motor MT, the second terminal of the second phase coil COILV of motor MT, and the second terminal of the third phase coil COILW of motor MT are connected to a common contact COM.

[0028] It is worth noting that when the speed of the motor MT driven by the motor drive circuit 100 decreases significantly, the voltage of the first phase coil COILU of the motor MT gradually decreases, but the speed of the motor MT does not immediately drop to a low value. Due to the inertial characteristics of the motor MT, the back electromotive force BEMFU of the U phase of the motor MT is very large and proportional to the speed of the motor MT. At the same time, the duty cycle and conduction time of the lower bridge switch of the switching circuit (such as the first lower bridge switch TL1 in Figure 7) are large, so the reverse current will continue to increase to a high excess current value.

[0029] If a conventional motor driver does not have a unidirectional conducting element with single-conduction characteristics, excessive reverse current will flow to the upper bridge switch, then into the input power supply that supplies the first input voltage VINU, causing the input power supply to burn out. However, if the conventional motor driver has a unidirectional conducting element, such as the diode DINU shown in Figure 7, then excessive reverse current will flow into the input capacitor Cinu shown in Figure 7, causing the input capacitor Cinu to burn out. As a result, the conventional motor driver cannot operate normally.

[0030] To prevent the above situation from occurring, when the speed of the motor MT driven by the motor drive circuit 100 decreases significantly, the motor drive circuit 100 executes a protection procedure (as shown in step S101 of Figure 2). In the protection procedure, the motor drive circuit 100 shuts down the lower bridge switch of at least one of the multiple switching circuits, such as the first lower bridge switch TL1 shown in Figure 7 (as shown in step S101 of Figure 2). As a result, as shown in Figure 7, current I1 flows sequentially from the first input voltage VINU through diode DINU, the first upper bridge switch TH1, and the first phase coil COILU of the U phase of the motor MT. At the same time, due to the current continuity of the first phase coil COILU, another current I2 flows sequentially through the body diode DUL of the first lower bridge switch TL1 to the first phase coil COILU of the U phase of the motor MT. Until the speed of the motor MT changes little or no longer changes and enters a steady state, the motor drive circuit 100 stops executing the above protection procedure and resumes normal switching of multiple switching circuits to drive the motor MT to operate normally.

[0031] It is worth noting that if the protection procedure ends before the motor MT reaches a steady state during its transient decrease in speed, the protection procedure is too short, and the aforementioned motor driver burnout will still occur. Conversely, if the motor MT has already reached a steady state but the protection procedure is still being executed, the protection procedure is too long, causing excessive reverse current flowing through the body diode DUL of the first lower bridge switch TL1. This will lead to overheating of the first lower bridge switch TL1 and poor operating efficiency of the motor driver. Furthermore, when the first lower bridge switch TL1 switches from the switching state to the on state, the instantaneous change in current flowing through the first lower bridge switch TL1 cannot change smoothly as expected, and the motor MT's speed cannot reach the target speed.

[0032] Therefore, when the motor drive circuit 100 executes the protection program, the speed detection circuit 300 detects the speed of the motor MT multiple times and outputs each detected speed of the motor MT as a detected speed (as shown in step S102 of Figure 2).

[0033] The motor drive circuit 100 controls or modulates the end time / release time and duration of the protection procedure (as shown in step S103 of Figure 2) based on multiple detected speeds of the motor MT obtained from the speed detection circuit 300.

[0034] In other words, compared to traditional motor drivers and motor driving methods, the motor driver and motor driving method of the present invention have a more effective automatic protection release mechanism. The motor driver and motor driving method of the present invention can more appropriately control the execution time of the protection program. For example, the motor driving circuit 100 of the motor driver and motor driving method of the present invention can appropriately extend the execution time of the protection program until the state of the motor MT reaches a steady state (including, for example, the rotational speed of the motor MT reaching a steady state). The motor driving circuit 100 of the motor driver and motor driving method of the present invention can also release the protection program earlier when the motor MT has reached a steady state, so as to immediately restore normal drive of the motor MT when the protection program is no longer needed. Therefore, the motor driver and motor driving method of the present invention can achieve no reverse current backflow into the circuit elements at the input terminal of the motor driver and has a high drive rate for the motor MT.

[0035] Please refer to Figures 3 and 6, where Figure 3 is a block diagram of a motor driver with an automatic deactivation protection mechanism according to the second embodiment of the present invention, and Figure 6 is a circuit diagram of the output stage circuit and the motor of the motor driver with an automatic deactivation protection mechanism according to the first to third embodiments of the present invention.

[0036] The second embodiment of the present invention is identical to the first embodiment and will not be described again in this document.

[0037] As shown in Figure 3, in the second embodiment, the motor driver of the present invention includes a motor drive circuit 100, an output stage circuit 200, and a speed detection circuit 300, and further includes a sampling comparison time setting circuit 400. The motor drive circuit 100 includes a control circuit 101 and a drive circuit 102.

[0038] The control circuit 101 is connected to the speed detection circuit 300, the drive circuit 102, and the sampling comparison time setting circuit 400. The speed detection circuit 300 is located on the motor MT, in contact with the motor MT, or connected to the motor MT. The output stage circuit 200 is connected to the drive circuit 102 and the motor MT.

[0039] As shown in Figure 3, the drive circuit 102 connects to the control terminals of multiple upper bridge switches and multiple lower bridge switches of the output stage circuit 200, such as the control terminals of the first upper bridge switch TH1, the second upper bridge switch TH2, the third upper bridge switch TH3, the first lower bridge switch TL1, the second lower bridge switch TL2, and the third lower bridge switch TL3 shown in Figure 6.

[0040] The speed detection circuit 300 detects multiple speeds of the motor MT at multiple detection time points.

[0041] When the detected speed of motor MT changes from the first speed to the second speed and the second speed is greater than the speed difference between the first speed and the second speed is greater than a speed difference threshold, the control circuit 101 controls the drive circuit 102 to execute the above protection program.

[0042] The sampling comparison time setting circuit 400 sets multiple sampling time points after the initial time point of the protection program.

[0043] The control circuit 101 acquires multiple sampling time points set by the sampling comparison time setting circuit 400, and acquires multiple speeds of the motor MT detected by the speed detection circuit 300 at each of the multiple detection time points as multiple detection speeds. The multiple detection time points include multiple sampling time points. The control circuit 101 samples the multiple detection speeds from the multiple detection time points as multiple sampled speeds.

[0044] The speed detection circuit 300 controls or modulates the end time and duration of the protection program executed by the drive circuit 102 based on multiple sampled speeds.

[0045] For example, the control circuit 101 compares the two sampled speeds at each of the two sampled time points in multiple sampling time points to determine whether the motor MT has transitioned from a transient state to a steady state, and decides whether to control the drive circuit 102 to stop executing the protection program.

[0046] When the difference between two sampled speeds taken at any two sampling time points is not equal to zero or not less than a speed difference threshold, the control circuit 101 determines that the motor MT is in a transient state, and therefore continues to compare the multiple detected speeds as described above, and continues to control the drive circuit 102 to execute the protection program.

[0047] When the difference between two sampled speeds taken at any two sampling time points is equal to zero or less than a speed difference threshold, the control circuit 101 determines that the motor MT has transitioned from the rotating state to the steady state, and therefore stops comparing the multiple subsequently detected sampled speeds, and the control drive circuit 102 stops executing the protection program.

[0048] For example, the control circuit 101 can set or obtain a preset time length. When the control circuit 101 determines that the motor MT has transitioned from a transient state to a steady state before this preset time length has elapsed, the control circuit 101 controls the drive circuit 102 to shorten the time length for executing the aforementioned protection procedure, so that the actual execution time of the protection procedure is less than this preset time length. Conversely, when the control circuit 101 determines that the motor has not transitioned from a transient state to a steady state after a preset time length has elapsed, the control circuit 101 controls the drive circuit 102 to extend the original preset time length for executing the protection procedure, so that the actual execution time of the protection procedure is greater than this preset time length.

[0049] Please refer to Figures 4 and 5, where Figure 4 is a block diagram of a motor driver with an automatic protection release mechanism according to the third embodiment of the present invention, and Figure 5 is a flowchart of the steps of a motor driving method with an automatic protection release mechanism according to the third embodiment of the present invention.

[0050] The third embodiment of the present invention is the same as the first and second embodiments, and will not be repeated herein. As shown in FIG4, the motor driver of the third embodiment of the present invention includes, in addition to the motor drive circuit 100, the output stage circuit 200, the speed detection circuit 300, and the sampling comparison time setting circuit 400, a speed command detection circuit 500. The motor drive circuit 100 includes a control circuit 101 and a drive circuit 102. The speed command detection circuit 500 is connected to the control circuit 101.

[0051] The steps S11-S14, S21-S23, and S31-S38 of FIG. 5 in the motor drive method of the present invention can be executed by the motor driver of the present invention as shown in FIG. 4. In steps S11-S14, master control commands are detected and issued. In steps S21-S23, a protection program is executed. In particular, in steps S31-S38, the end time point / release time point of the protection program is controlled or adjusted. In practice, one or more of the steps S11-S14, S21-S23, and S31-S38 shown in FIG. 5 can be omitted.

[0052] In normal mode, control circuit 101 controls drive circuit 102 to normally drive the first upper bridge switch TH1, the second upper bridge switch TH2, the third upper bridge switch TH3, the first lower bridge switch TL1, the second lower bridge switch TL2, and the third lower bridge switch TL3 (as shown in step S11 of Figure 5).

[0053] The speed command detection circuit 500 detects an external master control command issued by the external master control device and outputs a master control command detection signal (as shown in steps S12 and S13 of Figure 5).

[0054] When the speed command detection circuit 500 detects that an external master control command instructs the motor MT to reduce its speed from a first speed to a second speed and the speed difference between the second speed and the first speed is greater than a speed difference threshold, the master control command detection signal output by the speed command detection circuit 500 contains a significant speed reduction command message.

[0055] The control circuit 101 controls the drive circuit 102 to drive the output stage circuit 200 based on a master control command detection signal received from the speed command detection circuit 500.

[0056] Control circuit 101 determines whether a main control command detection signal received from speed command detection circuit 500 contains a significant speed reduction command signal to indicate that the speed of motor MT is significantly reduced.

[0057] If the control circuit 101 determines that the external master control command does not indicate that the speed of the motor MT has dropped significantly, the control circuit 101 maintains the normal mode and controls the drive circuit 102 to drive the first upper bridge switch TH1, the second upper bridge switch TH2, the third upper bridge switch TH3, the first lower bridge switch TL1, the second lower bridge switch TL2 and the third lower bridge switch TL3 normally (as shown in step S11 of Figure 5).

[0058] Conversely, if the control circuit 101 determines that the speed of the motor MT indicated by the external master control command has decreased significantly, the control circuit 101 decides to control the drive circuit 102 to execute the protection program (as shown in step S21 of Figure 5).

[0059] It is worth noting that, in the protection procedure, the control circuit 101 controls the drive circuit 102 to reduce the duty cycle of the waveform of the lower bridge conduction time signal (e.g., the lower bridge conduction time signal LUS in Figure 7) of at least one of the multiple switching circuits (e.g., the first lower bridge switch TL1 in Figure 7) to 0% (as shown in step S22 of Figure 5). As a result, the first lower bridge switch TL1 remains in the closed state in the protection procedure (as shown in step S23 of Figure 5).

[0060] It is worth noting that when the protection procedure is executed (as shown in steps S21 to S23 of Figure 5), the motor driver of the present invention can immediately determine the time point at which the protection mechanism is automatically released (i.e., the end time point / release time point of the protection procedure mentioned above) (as shown in steps S31 to S38 of Figure 5), as explained in detail below.

[0061] The speed detection circuit 300 detects multiple speeds of the motor MT at multiple detection time points, and uses them as multiple detection speeds (as shown in step S31 of Figure 5).

[0062] The sampling comparison time setting circuit 400 sets multiple sampling time points (as shown in step S32 of Figure 5).

[0063] The control circuit 101 samples any two of the two detected speeds at any two sampling time points (as shown in step S33 of Figure 5), and calculates the speed difference between the two detected speeds of the motor MT at each of the two sampling time points (as shown in step S34 of Figure 5).

[0064] The control circuit 101 determines whether the speed difference between two detected speeds of the motor MT at any two sampling time points is less than a speed difference threshold value (as shown in step S35 of Figure 5).

[0065] If the speed difference between the two detected speeds of motor MT at any two sampling time points is not less than a speed difference threshold, the control circuit 101 determines that the speed of motor MT is still gradually decreasing, and therefore determines that motor MT is undergoing a transient change (as shown in step S36 of Figure 5). Therefore, the control circuit 101 then samples any two detected speeds at any two sampling time points (as shown in step S33 of Figure 5), and at least one of the two sampling time points in each sampling is different from one of the two sampling time points in the previous sampling.

[0066] Conversely, if the speed difference between the two detected speeds at any two sampling time points is less than a speed difference threshold, the control circuit 101 determines that the speed of the motor MT has stopped changing or the change is small, and thus determines that the motor MT has entered a steady state (as shown in step S37 of Figure 5).

[0067] When the control circuit 101 determines that the motor MT has entered a steady state (as shown in step S37 of Figure 5), the control circuit 101 controls the drive circuit 102 to stop executing the above-mentioned protection program (as shown in steps S21~S23 of Figure 5). Thus, the protection program is released. After the protection program is released, the control circuit 101 can control the drive circuit 102 to normally drive the first upper bridge switch TH1, the second upper bridge switch TH2, the third upper bridge switch TH3, the first lower bridge switch TL1, the second lower bridge switch TL2, and the third lower bridge switch TL3 in normal mode (as shown in step S11 of Figure 5).

[0068] Please refer to Figures 4 to 9, where Figures 8 and 9 are waveform diagrams of signals generated by the motor driver and motor driving method with automatic protection release mechanism according to the first to third embodiments of the present invention.

[0069] As shown in Figure 4, the drive circuit 102 of the motor driver of the present invention can generate a plurality of first waveform signals according to the control signal received from the control circuit 101. Each of the plurality of first waveform signals may contain a plurality of third harmonic waveforms that are the same as the first waveform signal SH in Figure 8, or in practice, contain a plurality of sine wave waveforms.

[0070] The drive circuit 102 can acquire or generate multiple second waveform signals. Each of the multiple second waveform signals may contain multiple triangular wave waveforms identical to the second waveform signal TR in FIG8, or in practice, multiple sawtooth wave waveforms.

[0071] The driving circuit 102 can compare the voltage levels of multiple first waveform signals with the voltage levels of multiple second waveform signals respectively, so as to set the duty cycle of multiple waveforms of multiple upper bridge conduction time signals respectively. The multiple waveforms of each of the multiple upper bridge conduction time signals may include multiple pulses, multiple square waves, or any combination thereof.

[0072] The driving circuit 102 outputs multiple upper bridge conduction time signals to the control terminals of the first upper bridge switch TH1, the second upper bridge switch TH2, and the third upper bridge switch TH3, respectively. The voltage levels of the multiple lower bridge conduction time signals output by the driving circuit 102 to the control terminals of the first lower bridge switch TL1, the second lower bridge switch TL2, and the third lower bridge switch TL3 may be opposite to the voltage levels of the multiple upper bridge conduction time signals.

[0073] When the speed command detection circuit 500 detects that an external master control command CMD issued by an external master control device has a first level representing that the speed of the motor MT has not dropped significantly from the speed, such as a high logic level as shown in Figure 8, the speed command detection circuit 500 outputs a master control command detection signal CMDTR with a second level, such as a low logic level as shown in Figure 9, as shown in Figures 8 and 9.

[0074] Next, the control circuit 101 outputs a protection program trigger signal PRT with a second level, such as a low logic level, based on a master control command detection signal CMDTR received from the speed command detection circuit 500, which has a second level, such as the low logic level shown in FIG8.

[0075] Next, the drive circuit 102 drives the output stage circuit 200 to remain in normal mode without switching to protection mode, based on a protection program trigger signal PRT with a second level, such as the low logic level shown in FIG8, received from the control circuit 101.

[0076] Within a complete cycle (including the working cycle and the non-working cycle) of each of the multiple waveforms of the first waveform signal SH shown in Figure 8, the control circuit 101 controls the drive circuit 102 to drive the output stage circuit 200, thereby controlling the six-step drive of the motor MT, such as a three-phase motor, indicated by the six-step drive signal DRSP shown in Figure 8.

[0077] In normal mode, the drive circuit 102 complementaryly switches the upper bridge switch and the lower bridge switch contained in each of the multiple switching circuits. As shown in Figures 7 to 9, the voltage level of the upper bridge conduction time signal HUS received by the control terminal of the first upper bridge switch TH1 output by the drive circuit 102 is opposite to the voltage level of the lower bridge conduction time signal LUS received by the drive circuit 102 output to the first lower bridge switch TL1. As a result, the drive circuit 102 complementaryly switches the first upper bridge switch TH1 and the first lower bridge switch TL1.

[0078] The upper bridge conduction time signal HUS shown in Figure 8 can be replaced with a pulse width modulation signal SPWM shown in Figure 9. The signal of the first node NDU between the second terminal of the first upper bridge switch TH1 and the second terminal of the first lower bridge switch TL1 shown in Figure 7 can be the same as the first node signal SNDU shown in Figure 8.

[0079] When the speed command detection circuit 500 detects an external master control command CMD issued by an external master control device, which has a second level representing a significant decrease in the speed of the motor MT from the speed, such as a low logic level in Figure 8, the speed command detection circuit 500 outputs a master control command detection signal CMDTR with a first level, as shown in Figure 9, which has a high level or a pulse.

[0080] Next, the control circuit 101 outputs a protection program trigger signal PRT with a pulse or a high logic level, as shown in Figure 8, based on a master control command detection signal CMDTR received from the speed command detection circuit 500, which has a first level as shown in Figure 9 and a high level or a pulse.

[0081] Next, the drive circuit 102 drives the output stage circuit 200 to switch from normal mode to protection mode according to a protection program trigger signal PRT with a pulse or a first level, such as the high logic level shown in FIG8, received from the control circuit 101, and keeps the output stage circuit 200 in protection mode during the working cycle of the waveform of the protection program trigger signal PRT.

[0082] In other words, the working period of the waveform of the protection program trigger signal PRT shown in Figure 8 is used as a protection program execution time Tp, and the output stage circuit 200 is kept in protection mode during this protection program execution time Tp.

[0083] When the output stage circuit 200 switches from normal mode to protection mode, as shown in Figures 8 and 9, the drive circuit 102 reduces the duty cycle of the lower bridge conduction time signal LUS to 0% within a protection program execution time Tp to keep the first lower bridge switch TL1 closed. Thus, as shown in Figure 8, no reverse current is generated in the motor MT current signal MTCR within a protection program execution time Tp.

[0084] The speed detection circuit 300 can detect the speed RPM of the motor MT multiple times and output it to the control circuit 101. The control circuit 101 can accumulate and count the number of times the speed detection circuit 300 detects the speed of the motor MT to generate a speed detection count value, and can generate a speed detection count signal RPMCT as shown in Figure 9 based on the multiple speed detection count values ​​generated separately.

[0085] The sampling comparison time setting circuit 400 can set multiple sampling time points after the rising edge or falling edge of the pulse of the master control command detection signal CMDTR. For example, the multiple sampling time points set by the sampling comparison time setting circuit 400 include multiple first sampling time points and multiple second sampling time points.

[0086] The sampling comparison time setting circuit 400 can output a first sampling time indication signal SAMA as shown in Figure 9 based on multiple first sampling time points. The multiple time points at which the first sampling time indication signal SAMA transitions from a low level to a high level are the multiple first sampling time points.

[0087] The sampling comparison time setting circuit 400 can output a second sampling time indication signal SAMB as shown in Figure 9 based on multiple second sampling time points. The multiple time points at which the second sampling time indication signal SAMB transitions from a low level to a high level are the multiple second sampling time points.

[0088] The control circuit 101 samples the speed of the motor MT detected by the speed detection circuit 300 at each of a plurality of sampling time points (including the plurality of first sampling time points and the plurality of second sampling time points mentioned above).

[0089] The sampling comparison time setting circuit 400 can set a sampling comparison count threshold value, for example, equal to the maximum value (e.g., peak value) among multiple values ​​of a sampling comparison count threshold signal CMCNT as shown in Figure 9.

[0090] The control circuit 101 can accumulate the number of times or the duration of the sampled motor MT speed (RPM) to generate a sample comparison count value. The control circuit 101 can generate a sample comparison trigger signal CMTG as shown in FIG9 based on the accumulated sample comparison count value.

[0091] When the accumulated sample-compare count value of the control circuit 101 increases to a sample-compare count threshold value, the control circuit 101 generates a sample-compare trigger signal CMTG with a pulse or a first level, such as a high level.

[0092] Within each working cycle of multiple waveforms, such as pulses, of the sampling comparison trigger signal CMTG, the control circuit 101 can calculate the difference between the speed RPM of the motor MT sampled at the first sampling time point and the speed RPM of the motor MT sampled at the second sampling time point as a speed difference value, and compare this speed difference value with a speed difference threshold value.

[0093] Before the speed difference is less than a speed difference threshold, the control circuit 101 continues to execute the protection program within the working cycle of the waveform of the protection program trigger signal PRT, i.e., a protection program execution time Tp, and samples the speed RPM of the motor MT subsequently detected, and calculates a speed difference between the subsequent first sampling time point and the second sampling time point.

[0094] When the speed difference between the motor MT's RPM at the first sampling time point and the motor MT's RPM at the second sampling time point is less than a speed difference threshold, the control circuit 101 outputs a protection program trigger signal PRT to the drive circuit 102, which changes from a high level to a low level. Based on the low-level protection program trigger signal PRT, the control circuit 102 switches the output stage circuit 200 from the protection mode (executing the protection program) back to the normal mode (not executing the protection program). Alternatively, the control circuit 101 may output a high-level lower bridge shutdown release signal LSOFFN, and the drive circuit 102 switches the output stage circuit 200 from the protection mode back to the normal mode based on the high-level lower bridge shutdown release signal LSOFFN.

[0095] In summary, this invention provides a motor driver and a motor driving method with an automatic protection release mechanism. The motor driver and motor driving method of this invention can appropriately control the end time and duration of the protection program, and in particular, release the protection program at an appropriate end time to achieve the effect of preventing reverse current backflow into the circuit elements at the input terminal of the motor driver, and also to achieve high driving efficiency for the motor.

[0096] The content disclosed above is only a preferred and feasible embodiment of the present invention, and is not intended to limit the scope of the patent application of the present invention. Therefore, all equivalent technical changes made using the contents of the present invention specification and drawings are included in the scope of the patent application of the present invention.

[0097] 100: Motor drive circuit 200: Output stage circuit 300: Rotational speed detection circuit MT: Motor S101~S103, S11~S14, S21~S23, S31~S38: Steps 101: Control Circuit 102: Drive Circuit 400: Sampling Comparison Time Setting Circuit 500: Speed ​​command detection circuit TH1: First bridge switch TH2: Second upper bridge switch TH3: Third upper bridge switch TL1: First lower bridge switch TL2: Second lower bridge switch TL3: Third lower bridge switch NDU: First Node NDV: Second Node NDW: Third Node COILU: First phase coil COILV: Second phase coil COILW: Third phase coil COM: Common Node VINU: First input voltage VINV: Second input voltage VINW: Third Input Voltage VGU: First reference potential VGV: Second reference potential VGW: Third Reference Potential BEMFU, BEMFV, BEMFW: Back Electromotive Force HUS, HVS, HWS: Bridge conduction time signals LUS, LVS, LWS: Downbridge conduction time signal Cinu: Input capacitor DINU: Diode DUL: Body Diode I1, I2: Current CMD: External Master Control Command PRT: Protection Trigger Signal Tp: Protects program execution time MTCR: Current signal SH: First waveform signal TR: Second waveform signal DRSP: Six-Step Motor Drive Signal SNDU: First Node Signal CMDTR: Master Control Command Detection Signal SPWM: Pulse Width Modulation Signal RPM: Rotational Speed RPMCT: Rotational Speed ​​Detection and Counting Signal SAMA: First Sampling Time Indicator Signal SAMB: Second Sampling Time Indicator Signal CMCNT: Sampling Comparison Count Threshold Signal CMTG: Sample Comparison Trigger Signal LSOFFN: Bridge Closure Cancellation Signal

Claims

1. A motor driver with an automatic protection release mechanism, comprising: an output stage circuit including a plurality of switching circuits, each of the switching circuits including: an upper bridge switch, a first terminal of the upper bridge switch coupled to an input voltage; and a lower bridge switch, the first terminal of the lower bridge switch connected to a second terminal of the upper bridge switch, the second terminal of the lower bridge switch grounded, and a node between the second terminal of the lower bridge switch and the first terminal of the upper bridge switch connected to one end of a motor; a motor drive circuit connected to the control terminals of each of the upper bridge switches and the control terminals of each of the lower bridge switches, configured to execute a protection program in which the lower bridge switch of at least one of the switching circuits is turned off; and a speed detection circuit connected to the motor drive circuit, configured to detect a plurality of speeds of the motor at a plurality of detection time points as a plurality of detection speeds; wherein the motor drive circuit is configured to control or modulate an end time point and a time length for executing the protection program based on the plurality of detection speeds.

2. The motor driver with an automatic protection release mechanism as claimed in claim 1, wherein the motor drive circuit comprises: a drive circuit connected to the control terminals of each of the upper bridge switches and the control terminals of each of the lower bridge switches, configured to execute the protection procedure on at least one of the switch circuits; and a control circuit connected to the speed detection circuit and the drive circuit, configured to control the end time point and the duration of the drive circuit executing the protection procedure based on the detected speed.

3. A motor driver with an automatic deactivation protection mechanism as described in claim 1, wherein, When the motor drive circuit determines that the motor has transitioned from a transient state to a steady state based on the detected rotational speed, the motor drive circuit stops executing the protection program.

4. A motor driver with an automatic deactivation protection mechanism as described in claim 3, wherein, When the speed difference between two detected speeds at any two of the multiple sampling time points is less than a speed difference threshold, the motor drive circuit stops executing the protection program.

5. The motor driver with an automatic deactivation protection mechanism as described in claim 4 further includes: a sampling comparison time setting circuit connected to the motor drive circuit and configured to set a plurality of the sampling time points after the initial time point of the protection procedure.

6. The motor driver with an automatic deactivation protection mechanism as described in claim 1 further comprises: a speed command detection circuit connected to the motor drive circuit and configured to detect an external master control command; wherein, When the external master control command instructs the motor to reduce its speed from a first speed to a second speed and the difference between the first speed and the second speed is greater than the speed difference threshold, the motor drive circuit executes the protection program.

7. A motor driving method with an automatic protection release mechanism, applicable to a motor connected to multiple switching circuits, wherein each switching circuit includes an upper bridge switch and a lower bridge switch, a first terminal of the upper bridge switch is coupled to an input voltage, a first terminal of the lower bridge switch is connected to a second terminal of the upper bridge switch, the second terminal of the lower bridge switch is grounded, and a node between the second terminal of the lower bridge switch and the first terminal of the upper bridge switch is connected to one end of the motor, the motor driving method with the automatic protection release mechanism comprising the following steps: executing a protection program, wherein the protection program closes the lower bridge switch of at least one of the switching circuits; detecting multiple rotational speeds of the motor at multiple detection time points, respectively, as multiple detection speeds; and controlling or adjusting an end time point and a time length of the protection program execution based on the multiple detection speeds.

8. The motor drive method with an automatic protection release mechanism as described in claim 7 further includes the following steps: determining whether the motor has transitioned from a transient state to a steady state based on the detected rotational speed; if not, continuing to execute the protection procedure; if so, stopping the execution of the protection procedure.

9. The motor drive method with an automatic deactivation protection mechanism as described in claim 7 further comprises the following steps: calculating a speed difference between two detected speeds of the motor at any two of a plurality of sampling time points; and determining whether the speed difference is less than a speed difference threshold value; if not, continuing to execute the protection procedure; if so, stopping the execution of the protection procedure.

10. The motor drive method with an automatic deactivation protection mechanism as described in claim 7 further comprises the following steps: detecting whether an external master control command indicates that the rotational speed of the motor decreases from a first rotational speed to a second rotational speed and a difference between the first rotational speed and the second rotational speed is greater than the rotational speed difference threshold value; if yes, executing the protection procedure; if no, not executing the protection procedure.

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