Motor drive with automatic de-protect mechanism and motor driving method

Abstract

The present application provides a motor driver with an automatic protection release mechanism and a motor driving method. The motor driver includes an output stage circuit, a motor driving circuit and a rotation speed detection circuit. The output stage circuit includes a plurality of switching circuits. Each switching circuit includes an upper bridge switch and a lower bridge switch. The motor driving circuit executes a protection program in which the lower bridge switch of at least one switching circuit is turned off. The rotation speed detection circuit detects a plurality of rotation speeds of the motor at a plurality of detection time points, respectively. The motor driving circuit controls or modulates an end time point and a time length of executing the protection program according to the plurality of detected rotation speeds.

Description

Technical Field

[0001] This invention relates to electric motor drives, and more particularly to an electric motor drive with an automatic protection release mechanism and an electric motor driving method. Background 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 detection speeds. The motor drive circuit controls or modulates the end time and duration of the protection program based on the multiple detection 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 electric motors. The motor is connected to multiple switching circuits. 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. 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 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 detection speeds; and controlling or modulating the end time and duration of the protection program execution based on the multiple detection 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 components 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. Attached Figure Description

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

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

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

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

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

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

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

[0016] Figure 8 The waveform diagrams are 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.

[0017] Figure 9 The waveform diagrams are 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. Detailed 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" as used herein may, depending on the actual situation, include any or more combinations of the associated listed items.

[0019] Please see Figure 1 , Figure 2 and Figure 6 and Figure 7 ,in Figure 1 This is a block diagram of a motor driver with an automatic protection release mechanism according to a first embodiment of the present invention. Figure 2 This is a flowchart illustrating the steps of the electric motor driving method with an automatic protection release mechanism according to the first embodiment of the present invention. Figure 6 The diagrams show the output stage circuit of the motor driver with an automatic protection release mechanism and the circuit diagram of the motor according to the first to third embodiments of the present invention. Figure 7 This is a schematic diagram showing the current flow in protection mode of the output stage circuit of the motor driver with automatic deactivation mechanism according to the first to third embodiments of the present invention.

[0020] like Figure 1 As shown, 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 suitable for applications such as Figure 1 The motor MT shown is, for example, but not limited to, the same as, such as Figure 6 The three-phase motor shown.

[0022] like Figure 1 The motor driver of the present invention shown is suitable for performing the motor driving method of the present invention, including, Figure 2 Steps S101 to S103 are shown.

[0023] like Figure 1 The output stage circuit 200 shown may include, for example: Figure 6The diagram shows multiple switching circuits, each of which 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] like Figure 6 As shown, 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. BEMFU is the back electromotive force of phase U of motor MT, BEMFV is the back electromotive force of phase V of motor MT, and BEMFW is the back electromotive force of phase W of motor MT.

[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 large and proportional to the speed of the motor MT. Simultaneously, the lower bridge switch of the switching circuit (e.g., Figure 7 The first lower bridge switch (TL1) has a large duty cycle and a long conduction time, so the reverse current will continue to increase to a high excess current value.

[0029] If a traditional motor driver does not have a unidirectional conduction component 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 a traditional motor driver does have... Figure 7 The diagram shows a unidirectional conduction component, for example... Figure 7 As shown in the diode DINU, excessive reverse current will then flow into it, as... Figure 7 The input capacitor Cinu shown was damaged, causing it to burn out. As a result, the conventional motor driver could not 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 program (such as...). Figure 2 Step S101). In the protection procedure, the motor drive circuit 100 shuts down the lower bridge switch of at least one of the plurality of switching circuits, for example... Figure 7 The first lower bridge switch TL1 shown (as shown) Figure 2 Step S101). The result is as follows: Figure 7 As shown, 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. Simultaneously, 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 change of the motor MT becomes small or stops changing, entering 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 normal operation.

[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 time 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 time 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 speed cannot reach the target speed.

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

[0033] The motor drive circuit 100, based on multiple detected speeds of the motor MT obtained from the speed detection circuit 300, controls or modulates the end time / release time and duration of the aforementioned protection program (e.g., ...). Figure 2 Step S103).

[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 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 restore normal drive of the motor MT in real time when the protection program is not needed. Therefore, the motor driver and motor driving method of the present invention can achieve no reverse current backflow into the circuit components at the input terminal of the motor driver and has a high drive rate for the motor MT.

[0035] Please see Figure 3 and Figure 6 ,in Figure 3 This is a block diagram of a motor driver with an automatic protection release mechanism according to a second embodiment of the present invention. Figure 6The diagram shows the output stage circuit of the motor driver with an automatic protection release mechanism and the circuit diagram of the motor 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 herein.

[0037] like Figure 3 As shown, 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, as well as 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] like Figure 3 The drive circuit 102 shown connects to the control terminals of multiple upper bridge switches and multiple lower bridge switches of the output stage circuit 200, for example... Figure 6 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 are shown. The control terminal of the first upper bridge switch TH1 receives an upper bridge conduction time signal HUS, and the first lower bridge switch TL1 receives a lower bridge conduction time signal LUS. The control terminal of the second upper bridge switch TH2 receives an upper bridge conduction time signal HVS, and the second lower bridge switch TL2 receives a lower bridge conduction time signal LVS. The control terminal of the third upper bridge switch TH3 receives an upper bridge conduction time signal HWS, and the third lower bridge switch TL3 receives a lower bridge conduction time signal LWS.

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

[0041] When the detected speed of the motor MT changes from the first speed to the second speed and the speed difference between the second speed and the first 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 detected at each of the multiple sampling 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 taken at each of the two sampling 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 a transient state to a 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, control circuit 101 can set or obtain a default time length. When control circuit 101 determines that motor MT has transitioned from a transient state to a steady state before this default time length has elapsed, control circuit 101 controls 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 default time length. Conversely, when control circuit 101 determines that the motor has not transitioned from a transient state to a steady state after a default time length has elapsed, control circuit 101 controls drive circuit 102 to extend the default time length for executing the protection procedure, so that the actual execution time of the protection procedure is greater than this default time length.

[0049] Please see Figure 4 and Figure 5 ,in Figure 4 This is a block diagram of a motor driver with an automatic protection release mechanism according to a third embodiment of the present invention. Figure 5This is a flowchart illustrating the steps of a motor driving method with an automatic protection release mechanism according to a 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. Figure 4 As shown, the motor driver of the third embodiment of the present invention includes a motor drive circuit 100, an output stage circuit 200, a speed detection circuit 300, and a sampling comparison time setting circuit 400, as well as 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 electric motor driving method of the present invention includes Figure 5 Steps S11 to S14, S21 to S23, and S31 to S38 can be derived from, for example Figure 4 The motor driver of the present invention is executed as shown. In steps S11 to S14, master control commands are detected and issued. In steps S21 to S23, a protection program is executed. In particular, in steps S31 to S38, the end / release time of the protection program is controlled or modulated. In practice, as... Figure 5 One or more of the steps S11 to S14, S21 to S23, and S31 to S38 shown may 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 (e.g., ...). Figure 5 Step S11).

[0053] The speed command detection circuit 500 detects an external master control command issued by an external master control device and outputs a master control command detection signal (e.g., ...). Figure 5 Steps S12 and S13).

[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 information.

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

[0057] If the control circuit 101 determines that the external master control command does not indicate a significant decrease in the speed of the motor MT, the control circuit 101 maintains normal mode and controls 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 (e.g., ...). Figure 5 Step S11).

[0058] Conversely, if the control circuit 101 determines that the external master control command indicates a significant decrease in the speed of the motor MT, the control circuit 101 decides to control the drive circuit 102 to execute a protection program (such as...). Figure 5 Step S21).

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

[0060] It is worth noting that when performing protection procedures (such as...) Figure 5 During steps S21 to S23), the motor driver of the present invention can determine the time point of automatic release of the protection mechanism in real time (i.e., the end time point / release time point of the protection program mentioned above) (e.g. Figure 5 Steps S31 to S38 are explained in detail below.

[0061] The speed detection circuit 300 detects multiple speeds of the motor MT at multiple detection time points, and uses these as multiple detection speeds (e.g., ...). Figure 5 Step S31).

[0062] The sampling comparison time setting circuit 400 sets multiple sampling time points (e.g., Figure 5 Step S32).

[0063] The control circuit 101 samples two detection speeds (e.g., any two samples taken at any two sampling time points from multiple sampling time points) Figure 5Step S33) calculates the speed difference between two detected speeds sampled at every two sampling time points of the motor MT (e.g., ...). Figure 5 Step S34).

[0064] Control circuit 101 determines whether the speed difference between two detected speeds sampled at any two sampling time points of motor MT is less than a speed difference threshold (e.g., ...). Figure 5 Step S35).

[0065] If the speed difference between two detected speeds sampled at any two sampling time points is not less than a speed difference threshold, the control circuit 101 determines that the speed of the motor MT is still gradually decreasing, and therefore determines that the motor MT is undergoing a transient change (e.g., ...). Figure 5 Step S36). Therefore, next, the control circuit 101 samples two detection speeds (e.g., at any two sampling time points from multiple sampling time points) respectively. Figure 5 In step S33), 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 two detected speeds sampled 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 accordingly determines that the motor MT has entered a steady state (e.g., Figure 5 Step S37).

[0067] When the control circuit 101 determines that the motor MT has entered a steady state (e.g.) Figure 5 During step S37), the control circuit 101 controls the drive circuit 102 to stop executing the above-mentioned protection procedure (such as...). Figure 5 (Steps S21 to S23). This releases the protection program. 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 (e.g., ...) in normal mode. Figure 5 Step S11).

[0068] Please see Figures 4 to 9 ,in Figure 8 and Figure 9 The waveform diagrams are 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.

[0069] like Figure 4As shown, the drive circuit 102 of the motor driver of the present invention can generate a plurality of first waveform signals based on the control signal received from the control circuit 101. Each of the plurality of first waveform signals may include... Figure 8 The first waveform signal SH is the same as multiple third harmonic waveforms, or in practice, it contains multiple sine wave waveforms.

[0070] The driving circuit 102 can acquire or generate a plurality of second waveform signals. Each of the plurality of second waveform signals may contain, with respect to, [other signals]. Figure 8 The second waveform signal TR is the same as multiple triangular wave waveforms, or in practice, it contains 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 can be opposite to the voltage levels of the multiple upper bridge conduction time signals.

[0073] When the speed command detection circuit 500 detects an external master control command CMD issued by an external master control device, it has a first level indicating that the speed of the motor MT has not decreased significantly from the original speed. Figure 8 When the logic level is high as shown, the speed command detection circuit 500 outputs as follows: Figure 8 and Figure 9 The example shown has a second level, for example Figure 9 The low logic level shown is the master control instruction detection signal CMDTR.

[0074] Next, the control circuit 101 outputs a master control command detection signal CMDTR with a second level, for example, a low logic level, received from the speed command detection circuit 500, based on the signal having a second level, for example, a low logic level. Figure 8 The low logic level shown is a protection program activation signal PRT.

[0075] Next, the drive circuit 102, based on the second level received from the control circuit 101, for example... Figure 8 The low logic level of the protection program activation signal PRT shown drives the output stage circuit 200 to remain in normal mode without switching to protection mode.

[0076] In such Figure 8 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, the control circuit 101 controls the drive circuit 102 to drive the output stage circuit 200, thereby controlling the output stage circuit 200 as shown. Figure 8 The six-step drive signal DRSP shown indicates the six-step drive of a motor MT, such as a three-phase motor.

[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. For example... Figures 7 to 9 As shown, 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 TL1. As a result, the drive circuit 102 complementaryly switches the first upper bridge switch TH1 and the first lower bridge switch TL1.

[0078] like Figure 8 The bridge conduction time signal HUS shown can be replaced with, for example, Figure 9 The image shows a pulse width modulation (SPWM) signal. (For example...) Figure 7 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 can be the same as that shown. Figure 8 The first node signal SNDU is shown.

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

[0080] Next, the control circuit 101, based on the first level received from the speed command detection circuit 500, performs the following... Figure 9 The shown signal is a master control command detection signal CMDTR with a high level or a pulse, to output a pulse or a first level, for example. Figure 8 The high logic level shown is a protection program activation signal PRT.

[0081] Next, the drive circuit 102, based on the pulse or first level received from the control circuit 101, Figure 8The high logic level protection program activation signal PRT shown drives the output stage circuit 200 to switch from normal mode to protection mode, and keeps the output stage circuit 200 in protection mode during the working cycle of the waveform of the protection program activation signal PRT.

[0082] In other words, such as Figure 8 The working period of the waveform of the protection program activation signal PRT shown is used as a protection program running time Tp. During this protection program running time Tp, the output stage circuit 200 is kept in protection mode.

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

[0084] The speed detection circuit 300 can repeatedly detect the speed (RPM) of the motor MT 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 series of speed detection count values ​​based on the multiple speed detection count values ​​generated separately. Figure 9 The image shows a rotational speed detection and counting signal RPMCT.

[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 a 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 based on multiple first sampling time points, such as... Figure 9 The first sampling time indicator signal SAMA is shown. The multiple times when the first sampling time indicator signal SAMA transitions from low level to high level are multiple first sampling time points.

[0087] The sampling comparison time setting circuit 400 can output a value based on multiple second sampling time points, such as... Figure 9 The second sampling time indication signal SAMB is shown. Multiple transitions of the second sampling time indication signal SAMB from low to high at various points in time constitute multiple second sampling time points.

[0088] The control circuit 101 samples the speed detection circuit 300 at each of the multiple sampling time points (including the multiple first sampling time points and multiple second sampling time points mentioned above) to detect the speed RPM of the motor MT.

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

[0090] Control circuit 101 can accumulate the number of times or the duration of the sampled motor speed (RPM) of the motor MT to generate a sampled comparison count value. Control circuit 101 can then generate a... Figure 9 The sample comparison activation signal CMTG is shown.

[0091] When the accumulated sample comparison count value of the control circuit 101 increases to a sample comparison count threshold, the control circuit 101 generates a sample comparison activation 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 activation 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 activation signal PRT, i.e., a protection program running 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 activation signal PRT to the drive circuit 102, which changes from a high level to a low level. Based on the low-level protection program activation signal PRT, the drive 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 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 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 components at the input terminal of the motor driver, and also to achieve high driving efficiency for the motor.

[0096] 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 drive having an automatic deprotection mechanism, characterized by, The motor driver with an automatic protection release mechanism includes: The output stage circuit includes multiple switching circuits, each of which includes: The upper bridge switch, wherein the first terminal of the upper bridge switch is coupled to the input voltage; and A lower bridge switch, the first end of which is connected to the second end of the upper bridge switch, the second end of which is grounded, and the node between the second end of the lower bridge switch and the first end of the upper bridge switch is connected to one end of the 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, is configured to execute a protection program in which at least one of the lower bridge switches of the switch circuit is turned off. as well as A speed detection circuit, connected to the motor drive circuit, is configured to detect multiple speeds of the motor at multiple detection time points as multiple detection speeds; The motor drive circuit is configured to control or modulate the end time and duration of the protection program based on the multiple detected rotational speeds.

2. The motor drive with automatic un-protect mechanism as claimed in claim 1, wherein, The motor drive circuit includes: A drive circuit, connected to the control terminals of each of the upper bridge switches and each of the lower bridge switches, is configured to execute the protection program on at least one of the switch circuits. as well as A control circuit, connected to the speed detection circuit and the drive circuit, is configured to control the drive circuit to execute the protection program at the end time and for the duration based on the detected speed.

3. The motor drive with automatic un-protect mechanism as claimed 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 speed, the motor drive circuit stops executing the protection program.

4. The motor drive with automatic un-protect mechanism according to claim 3, wherein, When the speed difference between two detected speeds sampled at any two sampling time points of the motor is less than a speed difference threshold, the motor drive circuit stops executing the protection program.

5. The motor drive with automatic un-protect mechanism according to claim 4, wherein, The motor driver with an automatic protection release mechanism also includes: The sampling comparison time setting circuit is connected to the motor drive circuit and is configured to set multiple sampling time points after the initial time point of the protection program.

6. The motor driver with an automatic protection release mechanism according to claim 1, characterized in that, The motor driver with an automatic protection release mechanism also includes: A speed command detection circuit is connected to the motor drive circuit and configured to detect external master control commands. Specifically, when the external master control command instructs the motor speed to decrease from a first speed to a second speed and the difference between the first speed and the second speed is greater than a speed difference threshold, the motor drive circuit executes the protection program.

7. A method for driving a motor with an automatic protection release mechanism, applicable to a motor, wherein the motor is connected to multiple switching circuits, wherein, Each of the aforementioned switching circuits includes an upper bridge switch and a lower bridge switch. The first terminal of the upper bridge switch is coupled to the 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: Execute a protection procedure, in which at least one of the lower bridge switches of the switching circuit is turned off; At multiple detection time points, multiple speeds of the motor are detected respectively, and these are used as multiple detection speeds; and Based on the multiple detected rotational speeds, the end time and duration of the protection program are controlled or modulated.

8. The electric motor driving method with an automatic protection release mechanism according to claim 7, characterized in that, The electric motor driving method with an automatic protection release mechanism further includes the following steps: Based on the detected rotational speed, it is determined whether the motor has transitioned from a transient state to a steady state. If not, the protection program continues to be executed; if so, the protection program is stopped.

9. The electric motor driving method with an automatic protection release mechanism according to claim 7, characterized in that, The electric motor driving method with an automatic protection release mechanism further includes the following steps: Calculate the speed difference between two detected speeds sampled at any two of the multiple sampling time points of the motor; and Determine whether the speed difference is less than a speed difference threshold. If not, continue executing the protection program; if yes, stop executing the protection program.

10. The electric motor driving method with an automatic protection release mechanism according to claim 7, characterized in that, The electric motor driving method with an automatic protection release mechanism further includes the following steps: If the external master control command indicates that the speed of the motor decreases 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 protection program is executed; otherwise, the protection program is not executed.

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