Motor control circuit

Abstract

The present invention discloses a motor control circuit. A first end of a first upper bridge transistor and a first end of a second upper bridge transistor are coupled to a shared voltage. A first end of a first lower bridge transistor is connected to a second end of the first upper bridge transistor. A first node between the first end of the first lower bridge transistor and the second end of the first upper bridge transistor is connected to a first end of a motor. A first end of a second lower bridge transistor is connected to a second end of a second upper bridge transistor. A second node between the first end of the second lower bridge transistor and the second end of the second upper bridge transistor is connected to a second end of the motor. Before the driver circuit switches the bridge circuit, the driver circuit adjusts at least one transistor so that current does not flow to the shared voltage.

Description

Technical Field

[0001] The present invention relates to a motor, and in particular to a motor control circuit. Background Art

[0002] The circuit components of electronic products generate heat during operation, especially in the enclosed casing of a server or other confined spaces. The heat generated by each circuit component circulates within the enclosure, heating other circuit components and potentially causing overheating and damage. Therefore, fans are essential in electronic products to cool the circuit components.

[0003] However, in the fan, the control circuit controls the operation of multiple transistors in the motor drive circuit to drive the motor to rotate. In this process, a reverse current is generated to charge the shared voltage coupled to the single-phase motor, causing the shared voltage to be too high, thereby causing damage to the transistors in the motor drive circuit. Summary of the Invention

[0004] The present invention addresses the technical problem of providing a motor control circuit suitable for use with a motor, addressing the shortcomings of the prior art. The circuit comprises a bridge circuit, a drive circuit, a control circuit, and a feedback circuit. The bridge circuit comprises a plurality of transistors, including a first upper bridge transistor, a first lower bridge transistor, a second upper bridge transistor, and a second lower bridge transistor. The first end of the first upper bridge transistor is coupled to a common voltage. The first end of the first lower bridge transistor is connected to the second end of the first upper bridge transistor. The second end of the first lower bridge transistor is grounded. A first node between the first end of the first lower bridge transistor and the second end of the first upper bridge transistor is connected to the first end of the motor. The first end of the second upper bridge transistor is coupled to the common voltage. The first end of the second lower bridge transistor is connected to the second end of the second upper bridge transistor. The second end of the second lower bridge transistor is grounded. A second node between the first end of the second lower bridge transistor and the second end of the second upper bridge transistor is connected to the second end of the motor. The drive circuit is connected to the control end of each transistor. The drive circuit is configured to switch each transistor on or off. The control circuit is connected to the drive circuit. The control circuit is configured to control the operation of the drive circuit. The feedback circuit is connected to the drive circuit, the control circuit, the first node, and the second node. The feedback circuit is configured to receive a voltage at the first node or the second node. The feedback circuit is configured to output a feedback signal to the driving circuit. The driving circuit adjusts the bridge circuit according to the feedback signal to adjust the voltage of the first node or the second node so that after the bridge circuit switches, the current of the motor does not recharge the shared voltage.

[0005] In one embodiment, the driving circuit turns off the first upper bridge transistor and the second upper bridge transistor, fully turns on or slightly turns on the first lower bridge transistor, and fully turns on or slightly turns on the second lower bridge transistor based on the control circuit and the feedback signal, so that current flows through the first lower bridge transistor and the second lower bridge transistor.

[0006] In one embodiment, the driving circuit turns off the first lower bridge transistor and the second lower bridge transistor, fully opens or slightly opens the first upper bridge transistor, and fully opens or slightly opens the second upper bridge transistor based on the control and feedback signals of the control circuit, so that the current of the motor flows through the first upper bridge transistor and the second upper bridge transistor.

[0007] In one embodiment, the driving circuit adjusts the bridge circuit according to the control of the control circuit and the feedback signal to adjust the voltage of the second node to be close to or equal to the shared voltage and the voltage of the first node to be close to or equal to zero, or to adjust the voltage of the first node to be close to or equal to the shared voltage and the voltage of the second node to be close to or equal to zero.

[0008] In one embodiment, the feedback circuit receives a signal from the first node or the second node to determine whether the current approaches zero.

[0009] In one embodiment, the feedback circuit includes an operational amplifier. A first input terminal of the operational amplifier is connected to the second node. A second input terminal of the operational amplifier is coupled to a common voltage or a reference voltage. An output terminal of the operational amplifier is connected to the control terminal of the second low-bridge transistor.

[0010] In one embodiment, the feedback circuit further includes a first voltage divider circuit. The first voltage divider circuit includes a first resistor and a second resistor. A first end of the first resistor is coupled to a shared voltage. A second end of the first resistor is connected to a first end of the second resistor, and a second end of the second resistor is grounded. A first input of the operational amplifier is connected to a second node. A second input of the operational amplifier is connected to a node between the second end of the first resistor and the first end of the second resistor.

[0011] In one embodiment, the feedback circuit further includes a second voltage divider circuit. The second voltage divider circuit includes a third resistor and a fourth resistor. A first end of the third resistor is connected to the second node. A second end of the third resistor is connected to the first end of the fourth resistor. A second end of the fourth resistor is grounded. A first input of the operational amplifier is connected to a node between the second end of the third resistor and the first end of the fourth resistor.

[0012] In one embodiment, the feedback circuit includes an operational amplifier. A first input terminal of the operational amplifier is connected to the first node. A second input terminal of the operational amplifier is coupled to a shared voltage or a reference voltage. An output terminal of the operational amplifier is connected to the control terminal of the first low-bridge transistor.

[0013] In one embodiment, the feedback circuit includes an operational amplifier. A first input terminal of the operational amplifier is grounded. A second input terminal of the operational amplifier is connected to the first node. An output terminal of the operational amplifier is connected to the control terminal of the first upper bridge transistor.

[0014] In one embodiment, the control circuit outputs an enable signal to enable the feedback circuit to remain turned on all the time, or to enable the feedback circuit to be turned on only during a period before the bridge circuit switches.

[0015] In one embodiment, the motor control circuit further includes a rotor position detection circuit connected to the control circuit. The rotor position detection circuit is configured to detect the position of the motor rotor, and the control circuit controls the drive circuit based on the position of the motor rotor.

[0016] As described above, the present invention provides a motor control circuit that, before switching a bridge circuit, first turns off a first high-bridge transistor and a second high-bridge transistor, fully turns on or partially turns on a first low-bridge transistor, and simultaneously fully turns on or partially turns on a second low-bridge transistor, thereby adjusting the voltage at a first node between a first end of the first low-bridge transistor and a second end of the first high-bridge transistor, or adjusting the voltage at a second node between a first end of the second low-bridge transistor and a second end of the second high-bridge transistor, to a target voltage. This allows current to flow through the first low-bridge transistor and the second low-bridge transistor to ground. Subsequently, when the bridge circuit is switched, no current flows back to the shared voltage, effectively preventing transistor damage due to excessively high shared voltages.

[0017] To further understand the features and technical contents of the present invention, please refer to the following detailed description and drawings of the present invention. However, the drawings provided are only for reference and illustration and are not intended to limit the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 FIG. 4 is a block diagram of a motor control circuit according to an embodiment of the present invention.

[0019] Figure 2 FIG. 1 is a circuit layout diagram of a bridge circuit and a motor of a motor control circuit according to an embodiment of the present invention.

[0020] Figure 3 FIG. 1 is a circuit layout diagram of a bridge circuit and a motor of a motor control circuit according to an embodiment of the present invention.

[0021] Figure 4 FIG. 1 is a circuit layout diagram of a bridge circuit and a motor of a motor control circuit according to an embodiment of the present invention.

[0022] Figure 5 FIG. 1 is a circuit layout diagram of a bridge circuit, a feedback circuit, and a motor of a motor control circuit according to an embodiment of the present invention.

[0023] Figure 6 FIG. 1 is a circuit layout diagram of a bridge circuit, a feedback circuit, and a motor of a motor control circuit according to an embodiment of the present invention.

[0024] Figure 7FIG. 1 is a circuit layout diagram of a bridge circuit, a feedback circuit, and a motor of a motor control circuit according to an embodiment of the present invention.

[0025] Figure 8 Schematic diagram of the current flow in a traditional bridge circuit.

[0026] Figure 9 FIG. 1 is a schematic diagram illustrating current flow in a bridge circuit of a motor control circuit according to an embodiment of the present invention.

[0027] Figure 10 FIG. 1 is a circuit layout diagram of a bridge circuit, a feedback circuit, and a motor of a motor control circuit according to an embodiment of the present invention.

[0028] Figure 11 FIG. 1 is a first flow chart of a motor control method according to an embodiment of the present invention.

[0029] Figure 12 FIG. 4 is a second flow chart of the motor control method according to an embodiment of the present invention. DETAILED DESCRIPTION

[0030] The following is an explanation of the embodiments of the present invention through specific embodiments. Those skilled in the art can understand the advantages and effects of the present invention from the contents disclosed in this specification. The present invention can be implemented or applied through other different specific embodiments, and the 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. In addition, the drawings of the present invention are only simple schematic illustrations and are not depicted according to actual dimensions. It is stated in advance. The following embodiments will further explain the relevant technical content of the present invention in detail, but the disclosed contents are not intended to limit the scope of protection of the present invention. In addition, the term "or" used herein may include any one or more combinations of the associated listed items depending on the actual situation.

[0031] See also Figure 1 , which is a block diagram of a motor control circuit according to an embodiment of the present invention.

[0032] The motor control circuit of the embodiment of the present invention may include the following Figure 1 The bridge circuit, drive circuit 10, feedback circuit 20, control circuit 30 and rotor position detection circuit 40 shown in the figure can be applied to a motor MT. The bridge circuit can include multiple transistors, such as Figure 1 Shown are a first upper bridge transistor H1 , a first lower bridge transistor L1 , a second upper bridge transistor H2 , and a second lower bridge transistor L2 .

[0033] A first terminal of the first upper transistor H1 can be coupled to a common voltage VCC. A second terminal of the first upper transistor H1 can be connected to a first terminal of the first lower transistor L1. A first node OUT1 between the first terminal of the first lower transistor L1 and the second terminal of the first upper transistor H1 can be connected to a first terminal of the motor MT. A second terminal of the first lower transistor L1 can be grounded GND.

[0034] A first terminal of the second upper transistor H2 can be coupled to a common voltage VCC. A second terminal of the second upper transistor H2 can be connected to a first terminal of the second lower transistor L2. A second node OUT2 between the first terminal of the second lower transistor L2 and the second terminal of the second upper transistor H2 can be connected to a second terminal of the motor MT. A second terminal of the second lower transistor L2 can be grounded GND.

[0035] The driving circuit 10 can be connected to the control terminal of the first upper bridge transistor H1, the control terminal of the first lower bridge transistor L1, the control terminal of the second upper bridge transistor H2 and the control terminal of the second lower bridge transistor L2. The driving circuit 10 can output multiple driving signals to multiple transistors such as Figure 1 The first upper bridge transistor H1 , the first lower bridge transistor L1 , the second upper bridge transistor H2 , and the second lower bridge transistor L2 are shown to switch each transistor on or off.

[0036] A rotor position detection circuit 40 may be provided in the motor MT. The rotor position detection circuit 40 may detect the position of the rotor of the motor MT. The control circuit 30 may be connected to the drive circuit 10 and the rotor position detection circuit 40. Based on the position of the rotor of the motor MT, the control circuit 30 may output multiple control signals to the drive circuit 10. The control circuit 30 may control the drive circuit 10 to output multiple drive signals to the control terminals of the multiple transistors based on the multiple control signals, thereby driving the multiple transistors on or off.

[0037] The control circuit 30 can be connected to the feedback circuit 20. Before controlling the driver circuit 10 to switch the bridge circuit (commutating the motor MT), the control circuit 30 can output an enable signal to enable the feedback circuit 20. For example, the feedback circuit 20 can be kept on permanently or only enabled for a short period before the bridge circuit switches. This is merely an example, and the present invention is not limited to this. The operating time of the feedback circuit 20 can be adjusted according to actual needs, and in actual operation, the operation related to the enable signal can be omitted.

[0038] It is worth noting that the feedback circuit 20 can be connected to the first node OUT1, the second node OUT2, and the driving circuit 10. The feedback circuit 20 can receive the voltages at the first node OUT1 and the second node OUT2. The feedback circuit 20 can output a feedback signal (when triggered by an enable signal from the control circuit 30).

[0039] Based on the feedback signal, the driver circuit 10 can adjust one or more of the first upper transistor H1, the first lower transistor L1, the second upper transistor H2, and the second lower transistor L2 of the bridge circuit before the bridge circuit switches, thereby adjusting the voltage of the first node OUT1 or the voltage of the second node OUT2, allowing current to flow from the bridge circuit to ground GND. This prevents the current from flowing back into the common voltage VCC after the bridge circuit switches, thereby preventing the common voltage VCC from being excessively high and potentially damaging the bridge circuit.

[0040] For example, the driver circuit 10 can, based on the feedback signal, turn off the first upper transistor H1 and the second upper transistor H2 of the bridge circuit, fully turn on or partially turn on the first lower transistor L1, and simultaneously fully turn on or partially turn on the second lower transistor L2 of the bridge circuit. In this case, current flows sequentially through the first lower transistor L1 and the second lower transistor L2 to ground GND, or flows sequentially through the first lower transistor L1 and the second lower transistor L2 to ground GND.

[0041] The driver circuit 10 can adjust the bridge circuit based on the feedback signal and the control signal from the control circuit 30 to adjust the voltage at the second node OUT2 to be close to or equal to the common voltage VCC, and the voltage at the first node OUT1 to be close to or equal to zero, but the present invention is not limited thereto. In practice, the driver circuit 10 can adjust the voltage at the first node OUT1 to be close to or equal to the common voltage VCC, and the voltage at the second node OUT2 to be close to or equal to zero. Alternatively, the driver circuit 10 can adjust the voltage at the first node OUT1 or the voltage at the second node OUT2 such that the ratio of the voltage at the first node OUT1 or the voltage at the second node OUT2 to the common voltage VCC is a predetermined ratio.

[0042] See also Figures 1 to 4 ,in Figure 2 A circuit layout diagram of a bridge circuit and a motor of a motor control circuit according to an embodiment of the present invention; Figure 3 A circuit layout diagram of a bridge circuit and a motor of a motor control circuit according to an embodiment of the present invention; Figure 4 FIG2 is a circuit layout diagram of a bridge circuit and a motor of a motor control circuit according to an embodiment of the present invention. The same points as above are not described here in detail.

[0043] like Figure 1 The driving circuit 10 shown can be Figure 2The first high-bridge transistor H1 and the second low-bridge transistor L2 of the bridge circuit are fully turned on, while the first low-bridge transistor L1 and the second high-bridge transistor H2 of the bridge circuit are simultaneously turned off. At this point, the voltage VOUT1 at the first node OUT1 between the first end of the first low-bridge transistor L1 and the second end of the first high-bridge transistor H1 may be close to or equal to the common voltage VCC, while the voltage VOUT2 at the second node OUT2 between the first end of the second low-bridge transistor L2 and the second end of the second high-bridge transistor H2 may be close to or equal to zero. Current IL flows sequentially from the common voltage VCC through the first high-bridge transistor H1 and the second low-bridge transistor L2, and finally to ground GND.

[0044] like Figure 4 As shown, the driving circuit 10 fully turns on the first lower bridge transistor L1 and the second upper bridge transistor H2 , and turns off the first upper bridge transistor H1 and the second lower bridge transistor L2 .

[0045] Generally speaking, when the bridge circuit is switched, the driving circuit 10 may switch the first upper bridge transistor H1 and the second lower bridge transistor L2 of the bridge circuit from Figure 2 The fully open state shown is switched to Figure 4 The off state shown in FIG. 1 is shown, and the first lower bridge transistor L1 and the second upper bridge transistor H2 of the bridge circuit are switched from Figure 2 The closed state shown is switched to Figure 4 As a result, some current may not flow to GND but still flow through the bridge circuit, causing the bridge circuit to switch to the fully open state. Figure 4 In the state shown, the current IL will (sequentially flow through the first low-bridge transistor L1 and the second high-bridge transistor H2 ) recharge the common voltage VCC.

[0046] Therefore, it is worth noting that in this embodiment, the driving circuit 10 changes the bridge circuit from Figure 2 The status shown switches to Figure 4 Before the status shown, Figure 3 That is, when switching the bridge circuit from Figure 2 The status switches to Figure 4 Before the state, execute the following Figure 3 It should be understood that in actual operation, it is also possible to change the bridge circuit from Figure 4 The status switches to Figure 2 The state of Figure 4 The status switches to Figure 2 Before the state of Figure 3 The same or similar protective operations shown.

[0047] like Figure 3As shown, the driver circuit 10 turns off the first high-bridge transistor H1 and the second high-bridge transistor H2 to prevent current from flowing through the first high-bridge transistor H1 or the second high-bridge transistor H2 to the common voltage VCC. Simultaneously, the driver circuit 10 fully turns on the first low-bridge transistor L1 and slightly turns on the second low-bridge transistor L2. This allows current to flow through the first low-bridge transistor L1, then slowly through the second low-bridge transistor L2, and finally to ground GND.

[0048] In actual operation, the driving circuit 10 can fully turn on the second low-bridge transistor L2 and adjust the first low-bridge transistor L1 to be slightly turned on, so that the current can slowly flow through the first low-bridge transistor L1, then through the second low-bridge transistor L2, and finally flow to the ground GND.

[0049] More specifically, the feedback circuit 20 receives the current flowing through the motor MT and the bridge circuit. When the feedback circuit 20 determines that the current is greater than a threshold, it outputs a feedback signal. The drive circuit 10 adjusts the bridge circuit according to the feedback signal. When the current flowing through the motor MT and the bridge circuit is less than the threshold, the drive circuit 10 adjusts the bridge circuit from Figure 3 The status shown switches to Figure 4 The status shown.

[0050] See also Figure 1 and Figure 5 ,in Figure 5 FIG1 is a circuit layout diagram of a bridge circuit, a feedback circuit, and a motor of a motor control circuit according to an embodiment of the present invention. Similarities with the above are not repeated here.

[0051] like Figure 1 The feedback circuit 20 shown may include: Figure 5 The operational amplifier 51 is shown. A first input terminal, such as the non-inverting input terminal, of the operational amplifier 51 can be connected to the second node OUT2. A second input terminal, such as the inverting input terminal, of the operational amplifier 51 can be coupled to the common voltage VCC (or a reference voltage). An output terminal of the operational amplifier 51 can be connected to the control terminal of the second low-bridge transistor L2.

[0052] The second input terminal of the operational amplifier 51 receives the common voltage VCC, so that the voltage of the first input terminal of the operational amplifier 51 , ie, the voltage VOUT2 of the second node OUT2 (from zero voltage) is pulled up to be equal to the common voltage VCC.

[0053] See also Figure 1 and Figure 6 ,in Figure 6 FIG1 is a circuit layout diagram of a bridge circuit, a feedback circuit, and a motor of a motor control circuit according to an embodiment of the present invention. Similarities with the above are not repeated here.

[0054] like Figure 1The feedback circuit 20 shown may only include Figure 6 The operational amplifier 52 and the first voltage divider circuit 62 are shown. The first voltage divider circuit 62 may include a first resistor R3 and a second resistor R4. A first end of the first resistor R3 is coupled to a common voltage VCC (or a reference voltage). A second end of the first resistor R3 is connected to a first end of a second resistor R4. A second end of the second resistor R4 is connected to ground GND.

[0055] If the feedback circuit 20 only includes the operational amplifier 52 and the first voltage divider circuit 62, the first input terminal of the operational amplifier 52 can be directly connected to the second node OUT2. The second input terminal of the operational amplifier 52 is connected to the node between the second end of the first resistor R3 and the first end of the second resistor R4. In this way, the feedback circuit 20 can pull the voltage VOUT2 at the second node OUT2 to a voltage equal to the divided voltage of the common voltage VCC (i.e., the voltage across the second resistor R4).

[0056] If necessary, Figure 1 The feedback circuit 20 shown may further include a second voltage divider circuit 61. The second voltage divider circuit 61 may include a third resistor R1 and a fourth resistor R2. A first end of the third resistor R1 is connected to the second node OUT2. A second end of the third resistor R1 is connected to a first end of a fourth resistor R2. A second end of the fourth resistor R2 is connected to ground GND.

[0057] The first input terminal of the operational amplifier 52 is connected to a node between the second end of the third resistor R1 and the first end of the fourth resistor R2. The voltage at this node is the divided voltage of the voltage VOUT2 at the second node OUT2 (i.e., the voltage across the fourth resistor R2). The second input terminal of the operational amplifier 52 is connected to a node between the second end of the first resistor R3 and the first end of the second resistor R4. The voltage at this node is the divided voltage of the shared voltage VCC (i.e., the voltage across the second resistor R4).

[0058] If the resistance values ​​of the first resistor R3 and the third resistor R1 are the same, and the resistance values ​​of the second resistor R4 and the fourth resistor R2 are the same, the operational amplifier 52 can pull the voltage VOUT2 of the second node OUT2 to be equal to the common voltage VCC.

[0059] See also Figure 1 and Figure 7 ,in Figure 7 FIG1 is a circuit layout diagram of a bridge circuit, a feedback circuit, and a motor of a motor control circuit according to an embodiment of the present invention. Similarities with the above are not repeated here.

[0060] like Figure 1 The feedback circuit 20 shown may include: Figure 7The operational amplifier 53 is shown. A first input terminal of the operational amplifier 53, such as the inverting input terminal, can be connected to ground GND. A second input terminal of the operational amplifier 53, such as the non-inverting input terminal, can be connected to the first node OUT1. The output terminal of the operational amplifier 53 can be connected to the control terminal of the first upper bridge transistor H1. The second input terminal of the operational amplifier 53 receives a zero voltage. In this way, the voltage VOUT1 at the first node OUT1 can be pulled down to zero.

[0061] See also Figure 8 and Figure 9 ,in Figure 8 Schematic diagram of the current flow in a traditional bridge circuit; Figure 9 FIG. 1 is a schematic diagram illustrating current flow in a bridge circuit of a motor control circuit according to an embodiment of the present invention.

[0062] For example, if Figure 8 As shown, during high-speed operation of the motor, the first high-bridge transistor H1 and the second low-bridge transistor L2 of the conventional bridge circuit may be fully turned on, while the first low-bridge transistor L1 and the second high-bridge transistor H2 may be turned off. At this time, current IL flows sequentially from the second low-bridge transistor L2 through the motor MT and the first high-bridge transistor H1 to charge the common voltage VCC.

[0063] In order to prevent the current IL from recharging the common voltage VCC, in this embodiment, the driving circuit 10 first Figure 9 As shown, the first upper transistor H1 and the second upper transistor H2 of the bridge circuit of this embodiment are turned off. Simultaneously, the first lower transistor L1 is slightly turned on, and the second lower transistor L2 is fully turned on. Consequently, current IL sequentially flows through the second lower transistor L2, the motor MT, and the first lower transistor L1 to ground GND. Once current IL falls below a threshold, such as zero, the bridge circuit of this embodiment is switched back to the conventional bridge circuit described above.

[0064] Then, if Figure 8 As shown, the first high-bridge transistor H1 and the second low-bridge transistor L2 of the conventional bridge circuit are turned off, while the first low-bridge transistor L1 and the second high-bridge transistor H2 are fully turned on. At this time, the current IL flows from the first low-bridge transistor L1 through the motor MT and the second high-bridge transistor H2 in sequence to charge the common voltage VCC.

[0065] In order to prevent the current IL from recharging the common voltage VCC, in this embodiment, the driving circuit 10 first Figure 9As shown, the first high-bridge transistor H1 and the second high-bridge transistor H2 are turned off, while the first low-bridge transistor L1 is fully turned on and the second low-bridge transistor L2 is slightly turned on. Consequently, current IL sequentially flows through the first low-bridge transistor L1, the motor MT, and the second low-bridge transistor L2 to ground GND. Once current IL falls below a threshold, such as zero, the bridge circuit of this embodiment is switched back to the conventional bridge circuit described above.

[0066] That is, the motor control circuit of the present invention can activate the protection mechanism regardless of whether the motor is commutating or not commutating (for example, encountering unexpected rotation) to prevent current from flowing back to charge the shared voltage, for example, when the energy of the back electromotive force generated by the fan speed is greater than the shared voltage.

[0067] See also Figure 1 and Figure 10 ,in Figure 10 FIG. 1 is a circuit layout diagram of a bridge circuit, a feedback circuit, and a motor of a motor control circuit according to an embodiment of the present invention.

[0068] like Figure 1 The feedback circuit 20 shown may include: Figure 10 The operational amplifier 54 is shown. A first input terminal of the operational amplifier 54 can be connected to the first node OUT1 to obtain the voltage at the first node OUT1. A second input terminal of the operational amplifier 54 can be coupled to the common voltage VCC (or a reference voltage). The output terminal of the operational amplifier 54 can be connected to the control terminal of the first low-bridge transistor L1. In this way, the operational amplifier 54 can pull the voltage at the first node OUT1 to be equal to the common voltage VCC (or the reference voltage).

[0069] See also Figure 11 , which is a first flow chart of a motor control method according to an embodiment of the present invention.

[0070] The motor control method of the embodiment of the present invention may include the following steps: Figure 11 Steps S101 to S113 shown are applicable to Figure 1 The motor control circuit shown.

[0071] In step S101, the control circuit 30 outputs a high-level control signal to the driving circuit 10. The driving circuit 10 drives the second low-bridge transistor L2 to turn on according to the high-level control signal.

[0072] In step S103 , the control circuit 30 outputs a low-level control signal to the driving circuit 10 .

[0073] In step S105, the feedback circuit 20 determines whether the enable signal outputted by the control circuit 30 to the feedback circuit 20 is at a high level. If the enable signal outputted by the control circuit 30 to the feedback circuit 20 is not at a high level, step S107 is executed. Conversely, if the enable signal outputted by the control circuit 30 to the feedback circuit 20 is at a high level, step S109 is executed.

[0074] In step S107 , the feedback circuit 20 instructs the driving circuit 10 to drive the second low-bridge transistor L2 to turn off according to the low-level control signal output by the control circuit 30 .

[0075] In step S109, the feedback circuit 20 instructs the driver circuit 10 to fully turn on the second low-bridge transistor L2 to adjust the voltage at the second node OUT2. For example, the voltage at the second node OUT2 is adjusted to be close to or equal to the shared voltage, or equal to K times the reference voltage (where K is an appropriate value).

[0076] In step S111, the feedback circuit 20 determines whether the current IL flowing through the motor MT is greater than zero (e.g., based on the voltage of the first node OUT1 and / or the voltage of the second node OUT2). If the current IL of the motor MT is greater than zero, the process proceeds to step S109. If the current IL of the motor MT is not greater than zero, the process proceeds to step S113.

[0077] In step S113 , the feedback circuit 20 instructs the driving circuit 10 to drive the second low-bridge transistor L2 to turn off according to the low-level control signal output by the control circuit 30 .

[0078] See also Figure 12 , which is a second flow chart of the motor control method according to an embodiment of the present invention.

[0079] The motor control method of the embodiment of the present invention may include the following steps: Figure 11 Steps S201 to S213 shown are applicable to Figure 1 The motor control circuit shown.

[0080] In step S201, the control circuit 30 outputs a high-level control signal to the driving circuit 10. The driving circuit 10 drives the first high-bridge transistor H1 to turn on according to the high-level control signal.

[0081] In step S203 , the control circuit 30 outputs a low-level control signal to the driving circuit 10 .

[0082] In step S205, the feedback circuit 20 determines whether the enable signal outputted by the control circuit 30 to the feedback circuit 20 is at a high level. If the enable signal outputted by the control circuit 30 to the feedback circuit 20 is not at a high level, step S207 is executed. Conversely, if the enable signal outputted by the control circuit 30 to the feedback circuit 20 is at a high level, step S209 is executed.

[0083] In step S207 , the feedback circuit 20 instructs the driving circuit 10 to drive the first high-bridge transistor H1 to turn off according to the low-level control signal output by the control circuit 30 .

[0084] In step S209 , the feedback circuit 20 instructs the driving circuit 10 to adjust the first upper bridge transistor H1 to be slightly open, so as to adjust the voltage of the first node OUT1 . For example, the adjusted voltage of the first node OUT1 is close to or equal to zero.

[0085] In step S211, the feedback circuit 20 determines whether the current IL flowing through the motor MT is greater than zero (e.g., based on the voltage of the first node OUT1 and / or the voltage of the second node OUT2). If the current IL of the motor MT is greater than zero, the process proceeds to step S209. If the current IL of the motor MT is not greater than zero, the process proceeds to step S213.

[0086] In step S213 , the feedback circuit 20 instructs the driving circuit 10 to drive the first high-bridge transistor H1 to turn off according to the low-level control signal output by the control circuit 30 .

[0087] In summary, the present invention provides a motor control circuit that, before switching bridge circuits, first turns off a first high-bridge transistor and a second high-bridge transistor, fully turns on or partially turns on a first low-bridge transistor, and simultaneously fully turns on or partially turns on a second low-bridge transistor. This adjusts the voltage at a first node between the first end of the first low-bridge transistor and the second end of the first high-bridge transistor, or adjusts the voltage at a second node between the first end of the second low-bridge transistor and the second end of the second high-bridge transistor, to a target voltage. This allows current to flow through the first low-bridge transistor and the second low-bridge transistor to ground. Subsequently, when the bridge circuits are switched, no current flows back to the shared voltage, effectively preventing transistor damage due to excessively high shared voltages.

[0088] The contents disclosed above are only preferred feasible embodiments of the present invention and are not intended to limit the claims of the present invention. Therefore, all equivalent technical changes made using the description and drawings of the present invention are included in the claims of the present invention.

Claims

1. A motor control circuit, suitable for a motor, characterized in that: The motor control circuit comprises: A bridge circuit includes a plurality of transistors, wherein the plurality of transistors include: a first upper bridge transistor, wherein a first terminal of the first upper bridge transistor is coupled to a shared voltage; a first lower bridge transistor, wherein a first end of the first lower bridge transistor is connected to the second end of the first upper bridge transistor, the second end of the first lower bridge transistor is grounded, and a first node between the first end of the first lower bridge transistor and the second end of the first upper bridge transistor is connected to the first end of the motor; a second upper bridge transistor, wherein a first terminal of the second upper bridge transistor is coupled to the shared voltage; as well as a second lower bridge transistor, wherein a first end of the second lower bridge transistor is connected to the second end of the second upper bridge transistor, the second end of the second lower bridge transistor is grounded, and a second node between the first end of the second lower bridge transistor and the second end of the second upper bridge transistor is connected to the second end of the motor; a driving circuit connected to the control terminal of each of the transistors, the driving circuit being configured to switch each of the transistors on or off; a control circuit connected to the driving circuit, wherein the control circuit is configured to control the operation of the driving circuit; as well as a feedback circuit connected to the drive circuit, the control circuit, the first node, and the second node, configured to receive a voltage at the first node or the second node, the feedback circuit outputting a feedback signal to the drive circuit, the drive circuit regulating the bridge circuit based on the feedback signal and a control signal from the control circuit, to adjust the voltage at the first node to be close to or equal to zero and the voltage at the second node to be close to or equal to the shared voltage, so that after the bridge circuit switches, the current of the motor does not recharge the shared voltage; The driving circuit is configured to adjust the bridge circuit according to the feedback signal, turn off the first upper bridge transistor and the second upper bridge transistor to prevent the current from flowing through the first upper bridge transistor or the second upper bridge transistor to the shared voltage, and at the same time fully turn on the first lower bridge transistor and adjust the second lower bridge transistor to be slightly open, so that the current flows through the first lower bridge transistor and the second lower bridge transistor in sequence and finally flows to the ground, wherein when the second lower bridge transistor is adjusted to be slightly open, the current can only flow slowly through the second lower bridge transistor.

2. The motor control circuit according to claim 1, wherein: The feedback circuit receives a signal from the first node or the second node to determine whether the current approaches zero.

3. The motor control circuit according to claim 1, wherein: The feedback circuit includes an operational amplifier, a first input terminal of the operational amplifier is connected to the second node, a second input terminal of the operational amplifier is coupled to the shared voltage or a reference voltage, and an output terminal of the operational amplifier is connected to the control terminal of the second low-bridge transistor.

4. The motor control circuit according to claim 3, wherein: The feedback circuit further comprises: a first voltage divider circuit comprising a first resistor and a second resistor, wherein a first end of the first resistor is coupled to the shared voltage, a second end of the first resistor is connected to a first end of the second resistor, and a second end of the second resistor is grounded; The first input terminal of the operational amplifier is connected to the second node, and the second input terminal of the operational amplifier is connected to a node between the second end of the first resistor and the first end of the second resistor.

5. The motor control circuit according to claim 4, wherein: The feedback circuit further comprises: a second voltage divider circuit comprising a third resistor and a fourth resistor, wherein a first end of the third resistor is connected to the second node, a second end of the third resistor is connected to a first end of the fourth resistor, and a second end of the fourth resistor is grounded; and The first input terminal of the operational amplifier is connected to a node between the second terminal of the third resistor and the first terminal of the fourth resistor.

6. The motor control circuit according to claim 1, wherein: The feedback circuit includes an operational amplifier, a first input terminal of the operational amplifier is connected to the first node, a second input terminal of the operational amplifier is coupled to the shared voltage or the reference voltage, and an output terminal of the operational amplifier is connected to the control terminal of the first low-bridge transistor.

7. The motor control circuit according to claim 1, wherein: The feedback circuit includes an operational amplifier, a first input terminal of the operational amplifier is grounded, a second input terminal of the operational amplifier is connected to the first node, and an output terminal of the operational amplifier is connected to the control terminal of the first upper bridge transistor.

8. The motor control circuit according to claim 1, wherein: The control circuit outputs an enabling signal to enable the feedback circuit to remain turned on all the time, or to enable the feedback circuit to be turned on only within a period of time before the bridge circuit switches.

9. The motor control circuit according to claim 1, wherein: The motor control circuit further includes a rotor position detection circuit connected to the control circuit and configured to detect the position of the motor's rotor. The control circuit controls the drive circuit based on the position of the motor's rotor.

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