Motor driving device, motor driving system, and motor driving semiconductor integrated circuit device

Abstract

To provide a motor drive device capable of blocking a reverse current flowing due to reverse connection of a power supply or the like.SOLUTION: A first transistor for motor driving including a first terminal, a second terminal, a first electrode connected to the first terminal, a second electrode connected to the second terminal, and a gate connected to a first gate line, and a drive control unit configured to switch the first transistor by controlling a voltage of the gate via the first gate line, A first reverse current blocking circuit configured to set a state between the first terminal and the first gate line to a cut-off state when a voltage of the first terminal is higher than a voltage of the gate, wherein the first reverse current blocking circuit turns off the first transistor by setting a state between the first terminal and the first gate line to a connection state when the voltage of the first terminal is lower than the voltage of the gate.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a motor drive device, a motor drive system, and a semiconductor integrated circuit device for driving a motor. [Background technology]

[0002] Conventionally, a motor drive device is known that includes a clamp switch provided between a first potential line and a terminal of a coil, and a reverse current blocking diode connected in series to the clamp switch between the first potential line and the terminal of the coil (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2015-119625 Summary of the Invention [Problem to be solved by the invention]

[0004] The power supply for driving a motor may be connected with the polarity reversed (reverse connection) due to human error, etc. If a current flows in the opposite direction to the normal direction (reverse current) due to reverse connection of the power supply, the circuit through which the reverse current flows may be damaged.

[0005] An object of the present disclosure is to prevent reverse current from flowing due to reverse connection of a power supply or the like. [Means for solving the problem]

[0006] A motor drive device according to one aspect of the present disclosure includes: A first terminal; A second terminal; a first transistor for driving a motor, the first transistor having a first electrode connected to the first terminal, a second electrode connected to the second terminal, and a gate connected to a first gate line; a drive control unit that switches the first transistor by controlling a voltage of the gate via the first gate line; a first reverse current blocking circuit that is provided between the first terminal and the first gate line and that blocks communication between the first terminal and the first gate line when a voltage of the first terminal is higher than a voltage of the gate; When the voltage of the first terminal is lower than the voltage of the gate, the first reverse current blocking circuit connects the first terminal and the first gate line to turn off the first transistor. [Effects of the Invention]

[0007] According to one aspect of the present disclosure, it is possible to prevent reverse current from flowing due to reverse connection of a power supply or the like. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is an overall configuration diagram of a motor drive device according to a first embodiment of the present disclosure. [Figure 2] FIG. 10 is an overall configuration diagram of a motor drive device according to a second embodiment of the present disclosure. [Figure 3] 1 is an overall configuration diagram of a motor drive system according to an embodiment of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, the embodiments will be described with reference to the drawings. In each drawing, the same components are denoted by the same reference numerals, and duplicate explanations may be omitted. Note that "connection" is not limited to direct connection, but may also include conductive connection via a resistor or a diode (including a body diode of a transistor), etc.

[0010] <Motor driving device according to the first embodiment> 1 is an overall configuration diagram of a motor drive device 10 according to a first embodiment of the present disclosure. The motor drive device 10 drives a motor 11. The motor drive device 10 includes a motor drive integrated circuit (IC) 20, a first electrostatic discharge (ESD) protection element 23, a second ESD protection element 24, and a drive control unit 25.

[0011] Some or all of the first ESD protection element 23, the second ESD protection element 24, and the drive control unit 25 may be components of the motor drive IC 20. The motor drive device 10 may be a motor drive IC formed entirely from integrated circuits. The motor drive device 10 may be a circuit some of which is made up of discrete components. For example, the first ESD protection element 23 or the second ESD protection element 24 may be built into the motor drive IC, or may be a discrete component attached externally to the motor drive IC.

[0012] The motor drive device 10 includes a VCC terminal, a GND terminal, an OUT1 terminal, an OUT2 terminal, a VCC line 51, and a GND line 52. The VCC terminal is a power supply terminal electrically connected to the positive electrode of the power supply 32. The GND terminal is a power supply terminal (ground terminal) electrically connected to the negative electrode of the power supply 32. The power supply 32 is, for example, a DC power supply including a battery. The OUT1 terminal is a first drive terminal electrically connected to one end of the motor 11. The OUT2 terminal is a second drive terminal electrically connected to the other end of the motor 11. The VCC line 51 is a power supply line (positive line) electrically connected to the VCC terminal. The GND line 52 is a power supply line (negative line) electrically connected to the GND terminal. The VCC terminal, the GND terminal, the OUT1 terminal, the OUT2 terminal, the VCC line 51, and the GND line 52 may be components of the motor drive IC 20.

[0013] The motor drive device 10 normally operates on a DC power supply voltage indicated by V1 in the diagram. The power supply voltage V1 is generated by the power supply 32. V2 in the diagram indicates the reverse voltage when the power supply 32 is reverse-connected (V2 = -V1). P1 in the diagram indicates a first current path, which is the path of a current (reverse current) when the power supply 32 is reverse-connected. P2 indicates a second current path, which is the path of a current (reverse current) caused by the back electromotive force generated in the motor 11.

[0014] One end of motor 11 is electrically connected to the OUT1 terminal. The other end of motor 11 is electrically connected to the OUT2 terminal. The operating state of motor 11, such as the rotation direction or rotation speed, is controlled by motor drive device 10. Motor 11 may be a DC motor or an AC motor. Motor 11 is not limited to a rotary motor that generates rotational motion, but may also be a linear motor that generates linear motion.

[0015] The motor driving IC 20 is an example of a semiconductor integrated circuit device for driving a motor. The motor driving IC 20 is a semiconductor integrated circuit that drives the motor 11. The motor driving IC 20 includes a first reverse current blocking circuit 21, a second reverse current blocking circuit 22, a control line 41, a gate line 42, a gate line 43, transistors M5A, M5B, M6A, M6B, M7, and M8, resistors R1, R2, R3, R4, and R5, a diode D1, and a constant current source I. In this example, the motor driving IC 20 is connected to a drive control unit 25 that controls the driving of the motor 11.

[0016] The first reverse current blocking circuit 21 includes transistors M1 and M2, and the second reverse current blocking circuit 22 includes transistors M3 and M4.

[0017] In the motor drive device 10 according to the first embodiment, the transistors M1 to M8 are n-type MOSFETs (Metal-Oxide-Semiconductor Field-Effect Transistors). In this example, the transistor M5A will be described as the first transistor, the transistor M1 as the second transistor, the transistor M2 as the third transistor, the transistor M6A as the fourth transistor, the transistor M3 as the fifth transistor, and the transistor M4 as the sixth transistor.

[0018] The first ESD protection element 23 and the second ESD protection element 24 are provided to protect the motor driving IC 20 or the motor driving device 10, respectively, from electrostatic discharge. As will be described later, the first ESD protection element 23 and the second ESD protection element 24 can be used as paths to divert reverse current. The first ESD protection element 23 is provided between the OUT1 terminal and the GND terminal. The second ESD protection element 24 is provided between the OUT2 terminal and the GND terminal.

[0019] The motor driving IC 20 has an H-bridge driving circuit consisting of transistors M5A, M5B, M7, and M8 as a driving circuit for driving the motor 11. The transistor M6A functions as a switch for controlling the potential of the back gate of the transistor M5A. The transistor M6B functions as a switch for controlling the potential of the back gate of the transistor M5B. Note that while FIG. 1 illustrates an H-bridge driving circuit, the driving circuit for driving the motor 11 may be another type of circuit, such as a three-phase bridge driving circuit for driving a three-phase motor 11.

[0020] The transistor M5A is a high-side transistor having a drain connected to the VCC terminal, a source connected to the OUT1 terminal, and a gate connected to the gate line 42. The transistor M5A is an example of a first transistor for driving a motor. In the transistor M5A in FIG. 1, the drain connected to the VCC terminal is an example of a first electrode connected to a first terminal, and the source connected to the OUT1 terminal is an example of a second electrode connected to a second terminal. The gate line 42 is an example of a first gate line.

[0021] The gate of the transistor M5A is a control electrode connected to the gate line 42, and is connected to the drive control unit 25 via the gate line 42. A voltage VG4 from the gate line 42 is applied to the gate of the transistor M5A. The drain of the transistor M5A is connected to the VCC line 51 and the VCC terminal. The source of the transistor M5A is connected to the motor 11 via the OUT1 terminal, and is also connected to the drain of the transistor M7.

[0022] The transistor M6A is connected between the source of the transistor M5A and the back gate of the transistor M5A. The gate of the transistor M6A is a control electrode connected to the gate line 43 and is connected to the drive control unit 25 via the gate line 43. The gate line 43 is an example of a second gate line.

[0023] A voltage VG5 is applied to the gate of the transistor M6A from the gate line 43. The source of the transistor M6A is connected to the back gate of the transistor M5A. The drain of the transistor M6A is connected to the motor 11 via the OUT1 terminal, and is also connected to the source of the transistor M5A and the drain of the transistor M7.

[0024] Transistor M7 is a low-side transistor having a drain connected to the VCC terminal via transistor M5A, a source connected to the GND terminal, and a gate connected to gate line 44.

[0025] The gate of transistor M7 is a control electrode connected to gate line 44, and is connected to drive control unit 25 via gate line 44. The gate voltage of gate line 44 is applied to the gate of transistor M7. The drain of transistor M7 is connected to the source of transistor M5A, and is connected to VCC line 51 and the VCC terminal via transistor M5A. The drain of transistor M7 is connected to motor 11 via the OUT1 terminal. The source of transistor M7 is connected to ground (GND line 52 and GND terminal).

[0026] Transistor M5B is a high-side transistor having a drain connected to the VCC terminal, a source connected to the OUT2 terminal, and a gate connected to gate line 45.

[0027] The gate of transistor M5B is a control electrode connected to gate line 45, and is connected to drive control unit 25 via gate line 45. The gate voltage of gate line 45 is applied to the gate of transistor M5B. The drain of transistor M5B is connected to VCC line 51 and the VCC terminal. The source of transistor M5B is connected to motor 11 via the OUT2 terminal and is also connected to the drain of transistor M8.

[0028] The transistor M6B is connected between the source of the transistor M5B and the back gate of the transistor M5B. The gate of the transistor M6B is a control electrode connected to the gate line 46, and is connected to the drive control unit 25 via the gate line 46.

[0029] The gate of the transistor M6B is applied with the gate voltage of the gate line 46. The source of the transistor M6B is connected to the back gate of the transistor M5B. The drain of the transistor M6B is connected to the motor 11 via the OUT2 terminal, and is also connected to the source of the transistor M5B and the drain of the transistor M8.

[0030] The transistor M8 is a low-side transistor having a drain connected to the VCC terminal via the transistor M5B, a source connected to the GND terminal, and a gate connected to the gate line 47.

[0031] The gate of the transistor M8 is a control electrode connected to the gate line 47, and is connected to the drive control unit 25 via the gate line 47. The gate voltage of the gate line 47 is applied to the gate of the transistor M8. The drain of the transistor M8 is connected to the source of the transistor M5B, and is connected to the VCC line 51 and the VCC terminal via the transistor M5B. The drain of the transistor M8 is connected to the motor 11 via the OUT2 terminal. The source of the transistor M8 is connected to ground (GND line 52 and the GND terminal).

[0032] The drive control unit 25 controls the operation of the motor drive device 10 and also controls the driving of the motor 11. The drive control unit 25 is a program processing device having a configuration in which a processor such as a CPU, various storage devices such as RAM, ROM, and flash memory, and peripheral circuits such as a counter (timer), an A / D conversion circuit, a D / A conversion circuit, a clock generation circuit, and an input / output interface circuit are connected to one another via a bus or dedicated lines.

[0033] The drive control unit 25 is a circuit that operates on the power supply voltage between the VCC line 51 and the GND line 52. The drive control unit 25 switches the transistor M5A by controlling the voltage VG4 at the gate of the transistor M5A via the gate line 42. The drive control unit 25 controls the potential of the back gate of the transistor M5A by controlling the voltage VG5 at the gate of the transistor M6A via the gate line 43.

[0034] The first reverse current blocking circuit 21 is provided between the drain (VCC terminal or VCC line 51) of the transistor M5A and the gate line 42. When the voltage at the VCC terminal is higher than the voltage VG4 at the gate of the transistor M5A, the first reverse current blocking circuit 21 cuts off the connection between the drain (VCC terminal or VCC line 51) of the transistor M5A and the gate line 42. On the other hand, when the voltage at the VCC terminal is lower than the voltage VG4 at the gate of the transistor M5A, the first reverse current blocking circuit 21 connects the drain (VCC terminal or VCC line 51) of the transistor M5A and the gate line 42.

[0035] The first reverse current blocking circuit 21 includes transistors M1 and M2 connected in series between the drain (VCC terminal or VCC line 51) of transistor M5A and gate line 42. The gates of transistors M1 and M2 serve as control electrodes connected to control line 41, and are connected to voltage setting circuit 50 via control line 41. Voltage setting circuit 50 generates a control voltage VG1 for the first reverse current blocking circuit 21 from the voltage of VCC line 51. The control voltage VG1 from control line 41 is applied to the gates of transistors M1 and M2.

[0036] The transistors M1 and M2 form a back-to-back reverse current prevention circuit connected in series with the forward directions of their body diodes facing in opposite directions. The drain of the transistor M1 is connected to the gate line 42, and the source of the transistor M1 is connected to the source of the transistor M2. The drain of the transistor M2 is connected to the drain of the transistor M5A and the VCC terminal via the VCC line 51. The transistors M1 and M2 may form a back-to-back reverse current prevention circuit connected in series with a common source as shown in FIG. 1, or may form a back-to-back reverse current prevention circuit connected in series with a common drain.

[0037] The second reverse current blocking circuit 22 is provided between the drain (VCC terminal or VCC line 51) of the transistor M5A and the gate line 43. When the voltage of the VCC terminal is higher than the voltage VG5 of the gate of the transistor M6A, the second reverse current blocking circuit 22 cuts off the connection between the VCC terminal (VCC line 51) and the gate line 43. On the other hand, when the voltage of the VCC terminal is lower than the voltage VG5 of the gate of the transistor M6A, the second reverse current blocking circuit 22 connects the VCC terminal (VCC line 51) and the gate line 43.

[0038] The second reverse current blocking circuit 22 includes transistors M3 and M4 connected in series between the drain (VCC terminal or VCC line 51) of the transistor M5A and the gate line 43. The gates of the transistors M3 and M4 are control electrodes connected to the control line 41, and are connected to the voltage setting circuit 50 via the control line 41. A control voltage VG1 from the control line 41 is applied to the gates of the transistors M3 and M4.

[0039] The transistors M3 and M4 form a back-to-back reverse current prevention circuit connected in series with the forward directions of their body diodes facing in opposite directions. The drain of the transistor M3 is connected to the gate line 43, and the source of the transistor M3 is connected to the source of the transistor M4. The drain of the transistor M4 is connected to the drain of the transistor M5A and the VCC terminal via the VCC line 51. The transistors M3 and M4 may be connected in series in a back-to-back common source connection as shown in FIG. 1, or may be connected in series in a back-to-back common drain connection.

[0040] The voltage setting circuit 50 generates a control voltage VG1 for controlling the first reverse current blocking circuit 21 and the second reverse current blocking circuit 22 from the voltage of the VCC line 51. The voltage setting circuit 50 is a circuit that includes a constant current source I, a diode D1, and a resistor R3.

[0041] The constant current source I generates a control voltage VG1 by passing a current through a diode D1 and a resistor R3. The diode D1 is connected in series to the constant current source I. The anode of the diode D1 is electrically connected to the VCC line 51, and the cathode of the diode D1 is electrically connected to the gates of the transistors M1 to M4.

[0042] Resistor R3 has one end connected to control line 41 and the other end connected to the source of transistor M5A.

[0043] The gate line 42 is connected between the drive control unit 25 and the gate of the transistor M5A. The resistor R1 is inserted in series with the gate line 42. The voltage VG2 is the voltage of the gate line 42 between the resistor R1 and the drive control unit 25. The voltage VG4 is the voltage of the gate line 42 between the resistor R1 and the gate of the transistor M5A. The first reverse current blocking circuit 21 is connected to the gate line 42 between the resistor R1 and the gate of the transistor M5A.

[0044] The gate line 43 is connected between the drive control unit 25 and the gate of the transistor M6A. The resistor R2 is inserted in series with the gate line 43. The voltage VG3 is the voltage of the gate line 43 between the resistor R2 and the drive control unit 25. The voltage VG5 is the voltage of the gate line 43 between the resistor R2 and the gate of the transistor M6A. The second reverse current blocking circuit 22 is connected to the gate line 43 between the resistor R2 and the gate of the transistor M6A.

[0045] During normal operation, when the power supply 32 is electrically connected to the VCC and GND terminals with the correct polarity, a power supply voltage V1 is applied between the VCC and GND terminals. In this case, the potential of the VCC terminal is higher than the potential of the GND terminal. During normal operation, the drive control unit 25 controls a voltage VG4 that is approximately equal to voltage VG2 by controlling voltage VG2 to a high level or a low level. The drive control unit 25 controls voltage VG4 applied to the gate of transistor M5A to a high level or a low level, thereby turning transistor M5A on or off and controlling the current flowing between the drain and source of transistor M5A.

[0046] On the other hand, during normal operation, the drive control unit 25 outputs a voltage VG3 that turns on the transistor M6A, thereby applying a voltage VG5 that is approximately equal to the voltage VG3 to the gate of the transistor M6A. This turns on the transistor M6A, so that the back gate of the transistor M5A has the same potential as the source of the transistor M5A.

[0047] A control voltage VG1 (=Vt-α), which is set to a voltage that is lower by a predetermined voltage α than the gate threshold voltage Vt at which the corresponding transistor turns on, is applied to the gates of each of the transistors M1 to M4 via a control line 41. As a result, during normal operation, the control line 41 continues to supply the control voltage VG1, which cuts off the connection between the VCC terminal and the gate line 42, to the gates of the transistors M1 and M2 of the first reverse current blocking circuit 21. Similarly, during normal operation, the control line 41 continues to supply the control voltage VG1, which cuts off the connection between the VCC terminal and the gate line 43, to the gates of the transistors M3 and M4 of the second reverse current blocking circuit 22.

[0048] During normal operation, the voltage at the VCC terminal is equal to or greater than zero volts (VCC≧0). When VCC≧0, the voltage at the VCC terminal is equal to or greater than the voltage VG4 at the gate of transistor M5A, regardless of the level of voltage VG2, so transistors M1 and M2 are maintained in the off state. Similarly, when VCC≧0, the voltage at the VCC terminal is equal to or greater than the voltage VG5 at the gate of transistor M6A, regardless of the level of voltage VG3, so transistors M3 and M4 are maintained in the off state. Thus, during normal operation, reverse current flowing from the VCC terminal to gate line 42 via first reverse blocking circuit 21 is blocked by turning off transistors M1 and M2. Similarly, during normal operation, reverse current flowing from the VCC terminal to gate line 43 via second reverse blocking circuit 22 is blocked by turning off transistors M3 and M4.

[0049] On the other hand, when the power supply 32 is electrically connected to the VCC terminal and the GND terminal with opposite polarity (reverse connection), the potential of the VCC terminal becomes lower than the potential of the GND terminal and the OUT1 terminal, and the voltage of the VCC terminal and the VCC line 51 becomes negative. In this case, a current (reverse current) opposite to the forward current flowing during normal operation may flow through a path P1 that passes between the drain and source of the transistor M5A. The path P1 passes through the GND terminal, the transistor M7, the transistor M5A, the VCC terminal, and the power supply 32 in this order. Alternatively, when a back electromotive force is generated in the motor 11, the potential of the VCC terminal becomes lower than the potential of the OUT1 terminal, and the VCC terminal and the VCC line 51 become negative. In this case, a current (reverse current) opposite to the forward current flowing during normal operation may flow through a path P2 that passes between the drain and source of the transistor M5A. The path P2 is a flow path that passes through the GND terminal, the transistor M8, the OUT2 terminal, the motor 11, the OUT1 terminal, the transistor M5A, the VCC terminal, and the power supply 32 in this order.

[0050] When the voltage at the VCC terminal is negative, the voltage at the VCC terminal (negative voltage) is less than the voltage VG4 at the gate of transistor M5A, so transistors M1 and M2 switch from the off state to the on state. Similarly, when the voltage at the VCC terminal is negative, the voltage at the VCC terminal (negative voltage) is less than the voltage VG5 at the gate of transistor M6A, so transistors M3 and M4 switch from the off state to the on state. The level of negative voltage at the VCC terminal at which transistors M1, M2, M3, and M4 switch from the off state to the on state can be adjusted by the control voltage VG1. The control voltage VG1 is an adjustment voltage used to adjust the sensitivity at which transistors M1, M2, M3, and M4 switch from the off state to the on state.

[0051] When transistors M1 and M2 switch from an off state to an on state, the first reverse current blocking circuit 21 switches the connection between the VCC terminal and the gate line 42 from a cutoff state to a connection state. As a result, voltage VG4 becomes a negative voltage substantially equal to the VCC terminal (the drain of transistor M5A), and transistor M5A switches from an on state to an off state. This blocks reverse current flowing from the source to the drain of transistor M5A (reverse current flowing via path P1 or path P2). This reduces the possibility of damage to the circuit through which current flows via path P1 or path P2.

[0052] When transistors M3 and M4 switch from an off state to an on state, the second reverse current blocking circuit 22 switches the state between the VCC terminal and the gate line 43 from a cutoff state to a connection state. As a result, voltage VG5 becomes a negative voltage substantially equal to the VCC terminal (the drain of transistor M5A), and transistor M6A switches from an on state to an off state. This blocks reverse current (reverse current flowing through path P1 or path P2) that flows through transistor M6A, the backgate of transistor M5A, and the drain of transistor M5A in that order. This reduces the possibility of damage to the circuit through which current flows through path P1 or path P2.

[0053] As described above, the motor drive device 10 according to the first embodiment includes a first reverse current blocking circuit 21 that blocks a reverse current from the VCC terminal to the gate line 42 by disconnecting the VCC terminal from the gate line 42 when the voltage at the VCC terminal is higher than voltage VG4. When the voltage at the VCC terminal is lower than voltage VG4, the first reverse current blocking circuit 21 connects the VCC terminal to the gate line 42, turning off transistor M5A. When a reverse current flows from the source to the drain of transistor M5A, the voltage at the VCC terminal becomes lower than voltage VG4, and transistor M5A is therefore turned off by the first reverse current blocking circuit 21. As a result, a reverse current can be blocked from flowing from the source to the drain of transistor M5A.

[0054] The motor drive device 10 according to the first embodiment includes a control line 41 that supplies a control voltage VG1 for the first reverse current blocking circuit 21 to the first reverse current blocking circuit 21. When the voltage at the VCC terminal is higher than the voltage VG4, the first reverse current blocking circuit 21 is supplied with the control voltage VG1, thereby blocking the connection between the VCC terminal and the gate line 42.

[0055] The first reverse current blocking circuit 21 can adjust the sensitivity of switching the state between the VCC terminal and the gate line 42 from a cutoff state to a connection state according to the voltage value of the control voltage VG1. In other words, the first reverse current blocking circuit 21 can adjust the negative voltage at the VCC terminal at which the transistors M1 and M2 switch from an off state to an on state according to the voltage value of the control voltage VG1. The voltage value of the control voltage VG1 can be adjusted by the resistance value of the resistor R3 or the current value of the constant current source I.

[0056] The motor drive device 10 according to the first embodiment includes a second reverse current blocking circuit 22 that blocks reverse current from the VCC terminal to the gate line 43 by disconnecting the VCC terminal from the gate line 43 when the voltage at the VCC terminal is higher than voltage VG5. When the voltage at the VCC terminal is lower than voltage VG5, the second reverse current blocking circuit 22 connects the VCC terminal to the gate line 43, turning off transistor M6A. When a reverse current flows from the source to the drain of transistor M5A, the voltage at the VCC terminal becomes lower than voltage VG5, and transistor M6A is turned off by the second reverse current blocking circuit 22. As a result, reverse current can be prevented from flowing from the source of transistor M6A to the drain of transistor M5A via the back gate of transistor M5A.

[0057] The motor drive device 10 according to the first embodiment includes a first ESD protection element 23 connected to the OUT1 terminal. By turning off the transistor M5A and the transistor M6A, a reverse current generated due to reverse connection of the power supply 32 or the like can be diverted to the first ESD protection element 23. A reverse current generated due to reverse connection of the power supply 32 or the like can also be diverted to the second ESD protection element 24.

[0058] The motor drive device 10 according to the first embodiment includes a control line 41 that supplies a control voltage VG1 for the second reverse current blocking circuit 22 to the second reverse current blocking circuit 22. When the voltage at the VCC terminal is higher than the voltage VG5, the second reverse current blocking circuit 22 is supplied with the control voltage VG1, thereby blocking the connection between the VCC terminal and the gate line 43.

[0059] The second reverse current blocking circuit 22 can adjust the sensitivity of switching the state between the VCC terminal and the gate line 43 from a cutoff state to a connection state according to the voltage value of the control voltage VG1. In other words, the second reverse current blocking circuit 22 can adjust the negative voltage at the VCC terminal at which the transistors M3 and M4 switch from an off state to an on state according to the voltage value of the control voltage VG1. The voltage value of the control voltage VG1 can be adjusted by the resistance value of the resistor R3 or the current value of the constant current source I.

[0060] 1 have the same functions as transistors M5A and M6A and resistors R1 and R2, respectively. Although not shown in FIG. 1, a reverse current blocking circuit having the same configuration and function as first reverse current blocking circuit 21 may be provided between the drain of transistor M5B and gate line 45 to block reverse current flowing through transistor M5B. Although not shown in FIG. 1, a reverse current blocking circuit having the same configuration and function as second reverse current blocking circuit 22 may be provided between the drain of transistor M5B and gate line 46 to block reverse current flowing through transistor M6B.

[0061] Although not shown in Fig. 1, a reverse current blocking circuit having a configuration and function similar to that of the first reverse current blocking circuit 21 may be provided between the drain of transistor M7 and the gate line 44 in order to block reverse current flowing through transistor M7. Although not shown in Fig. 1, a circuit having a configuration and function similar to that of transistor M6A and second reverse current blocking circuit 22 may be connected to transistor M7. The same applies to transistor M8.

[0062] <Motor drive device according to the second embodiment> 2 is an overall configuration diagram of a motor drive device 10 according to a second embodiment of the present disclosure. In the second embodiment, the description of the configuration and operation similar to those of the first embodiment will be omitted by referencing the above description. The motor drive device 10 according to the second embodiment differs from the motor drive device 10 according to the first embodiment in that the transistors M1, M2, M3, M4, M5A, M5B, M6A, and M6B are p-type MOSFETs.

[0063] The transistor M5A is a high-side transistor having a drain connected to the OUT1 terminal, a source connected to the VCC terminal, and a gate connected to the gate line 42. The transistor M5A is an example of a first transistor for driving a motor. In the transistor M5A in FIG. 2, the drain connected to the OUT1 terminal is an example of a first electrode connected to a first terminal, and the source connected to the VCC terminal is an example of a second electrode connected to a second terminal.

[0064] The drain of the transistor M5A is connected to the OUT1 terminal. The source of the transistor M5A is connected to the VCC line 51 and the VCC terminal. The drain of the transistor M6A is connected to the back gate of the transistor M5A. The source of the transistor M6A is connected to the source of the transistor M5A, the VCC line 51, and the VCC terminal.

[0065] The first reverse current blocking circuit 21 is provided between the drain (OUT1 terminal) of the transistor M5A and the gate line 42. When the voltage of the OUT1 terminal is higher than the gate voltage VG4 of the transistor M5A, the first reverse current blocking circuit 21 cuts off the connection between the OUT1 terminal and the gate line 42. On the other hand, when the voltage of the OUT1 terminal is lower than the gate voltage VG4 of the transistor M5A, the first reverse current blocking circuit 21 connects the OUT1 terminal and the gate line 42.

[0066] The first reverse current blocking circuit 21 includes transistors M1 and M2 connected in series between the drain (OUT1 terminal) of transistor M5A and a gate line 42. The gates of transistors M1 and M2 are control electrodes connected to a control line 41, and are connected to a voltage setting circuit 50 via the control line 41. The voltage setting circuit 50 generates a control voltage VG1 for the first reverse current blocking circuit 21 from the voltage of the VCC line 51. The control voltage VG1 from the control line 41 is applied to the gates of transistors M1 and M2.

[0067] The transistors M1 and M2 are connected in series in a back-to-back configuration to form a reverse current prevention circuit, with the forward directions of their body diodes facing in opposite directions. The drain of the transistor M1 is connected to the gate line 42, and the source of the transistor M1 is connected to the source of the transistor M2. The drain of the transistor M2 is connected to the drain of the transistor M5A and the OUT1 terminal.

[0068] The second reverse current blocking circuit 22 is provided between the drain (OUT1 terminal) of the transistor M5A and the gate line 43. When the voltage of the OUT1 terminal is higher than the voltage VG5 of the gate of the transistor M6A, the second reverse current blocking circuit 22 cuts off the connection between the drain (OUT1 terminal) of the transistor M5A and the gate line 43. On the other hand, when the voltage of the OUT1 terminal is lower than the voltage VG5 of the gate of the transistor M6A, the second reverse current blocking circuit 22 connects the drain (OUT1 terminal) of the transistor M5A and the gate line 43.

[0069] The second reverse current blocking circuit 22 includes transistors M3 and M4 connected in series between the drain (OUT1 terminal) of the transistor M5A and a gate line 43. The gates of the transistors M3 and M4 are control electrodes connected to a control line 41, and are connected to the voltage setting circuit 50 via the control line 41. A control voltage VG1 from the control line 41 is applied to the gates of the transistors M3 and M4.

[0070] The transistors M3 and M4 are connected in series in a back-to-back configuration to form a reverse current prevention circuit, with the forward directions of their body diodes facing in opposite directions. The drain of the transistor M3 is connected to the gate line 43, and the source of the transistor M3 is connected to the source of the transistor M4. The drain of the transistor M4 is connected to the drain of the transistor M5A and the OUT1 terminal.

[0071] The voltage setting circuit 50 generates a control voltage VG1 for controlling the first reverse current blocking circuit 21 and the second reverse current blocking circuit 22 from the voltage of the VCC line 51. The voltage setting circuit 50 is a circuit that includes a constant current source I, a diode D1, and a resistor R3.

[0072] The constant current source I generates a control voltage VG1 by passing a current through a diode D1 and a resistor R3. The diode D1 is connected in series to the constant current source I. The cathode of the diode D1 is electrically connected to the GND line 52, and the anode of the diode D1 is electrically connected to the gates of the transistors M1 to M4.

[0073] Resistor R3 has one end connected to control line 41 and the other end connected to the source of transistor M5A.

[0074] During normal operation, when the power supply 32 is electrically connected to the VCC and GND terminals with the correct polarity, a power supply voltage V1 is applied between the VCC and GND terminals. In this case, the potential of the VCC terminal is higher than the potential of the GND terminal. During normal operation, the drive control unit 25 controls a voltage VG4 that is approximately equal to voltage VG2 by controlling voltage VG2 to a high level or a low level. The drive control unit 25 controls voltage VG4 applied to the gate of transistor M5A to a high level or a low level, thereby turning transistor M5A on or off and controlling the current flowing between the drain and source of transistor M5A.

[0075] On the other hand, during normal operation, the drive control unit 25 outputs a voltage VG3 that turns on the transistor M6A, thereby applying a voltage VG5 that is approximately equal to the voltage VG3 to the gate of the transistor M6A. This turns on the transistor M6A, so that the back gate of the transistor M5A has the same potential as the source of the transistor M5A.

[0076] A control voltage VG1 (=voltage at the VCC terminal-(Vt-α)), which is set to a voltage lower than the voltage at the VCC terminal by (gate threshold voltage Vt-predetermined voltage α), is applied to the gates of transistors M1 to M4 via a control line 41. As a result, during normal operation, the control line 41 continues to supply the control voltage VG1, which cuts off the connection between the OUT1 terminal and the gate line 42, to the gates of transistors M1 and M2 of the first reverse current blocking circuit 21. Similarly, during normal operation, the control line 41 continues to supply the control voltage VG1, which cuts off the connection between the OUT1 terminal and the gate line 43, to the gates of transistors M3 and M4 of the second reverse current blocking circuit 22. The predetermined voltage α is a positive value.

[0077] During normal operation, the voltage at the VCC terminal is equal to or greater than the voltage at the OUT1 terminal (VCC≧OUT1). When VCC≧OUT1, the voltage at the OUT1 terminal is equal to or greater than the voltage VG4 at the gate of transistor M5A, regardless of the level of voltage VG2, so transistors M1 and M2 are maintained in the off state. Similarly, when VCC≧OUT1, the voltage at the OUT1 terminal is equal to or greater than the voltage VG5 at the gate of transistor M6A, regardless of the level of voltage VG3, so transistors M3 and M4 are maintained in the off state. Thus, during normal operation, reverse current flowing from the drain of transistor M6A to gate line 42 via first reverse blocking circuit 21 is blocked by turning off transistors M1 and M2. Similarly, during normal operation, reverse current flowing from the drain of transistor M6A to gate line 43 via second reverse blocking circuit 22 is blocked by turning off transistors M3 and M4.

[0078] On the other hand, when the power supply 32 is electrically connected to the VCC terminal and the GND terminal with opposite polarity (reverse connection), the potential of the VCC terminal becomes lower than the potential of the GND terminal and the OUT1 terminal, and the voltage of the OUT1 terminal becomes the sum of the voltage of the VCC terminal and a predetermined voltage β (VCC + β). The predetermined voltage β is a positive value. In this case, a current (reverse current) opposite to the forward current flowing during normal operation may flow through a path P1 via the drain-source of the transistor M5A. Alternatively, when a back electromotive force is generated in the motor 11, the potential of the VCC terminal becomes lower than the potential of the GND terminal and the OUT1 terminal, and the voltage of the OUT1 terminal becomes (VCC + β). In this case, a current (reverse current) opposite to the forward current flowing during normal operation may flow through a path P2 via the drain-source of the transistor M5A.

[0079] When the voltage at the OUT1 terminal is (VCC + β), the voltage at the OUT1 terminal (VCC + β) is less than the gate voltage VG4 of transistor M5A, so transistors M1 and M2 switch from the off state to the on state. Similarly, when the voltage at the OUT1 terminal is (VCC + β), the voltage at the OUT1 terminal (VCC + β) is less than the gate voltage VG5 of transistor M6A, so transistors M3 and M4 switch from the off state to the on state. The voltage at the OUT1 terminal at which transistors M1, M2, M3, and M4 switch to the on state can be adjusted by the control voltage VG1.

[0080] When the transistors M1 and M2 switch from an off state to an on state, the first reverse current blocking circuit 21 switches the state between the OUT1 terminal and the gate line 42 from a cutoff state to a connection state. As a result, the voltage VG4 becomes substantially equal to the voltage at the OUT1 terminal (the drain of the transistor M5A), and the transistor M5A switches from an on state to an off state. This blocks reverse current flowing from the drain to the source of the transistor M5A (the reverse current flowing via path P1 or path P2). This reduces the possibility of damage to the circuit through which current flows via path P1 or path P2.

[0081] When transistors M3 and M4 switch from an off state to an on state, the second reverse current blocking circuit 22 switches the state between the OUT1 terminal and the gate line 43 from a cutoff state to a connection state. As a result, voltage VG5 becomes substantially equal to the voltage at the OUT1 terminal (the drain of transistor M5A), and transistor M6A switches from an on state to an off state. This blocks reverse current (reverse current flowing via path P1 or path P2) that flows in this order through the drain of transistor M5A, the backgate of transistor M5A, and transistor M6A. This reduces the possibility of damage to the circuit through which current flows via path P1 or path P2.

[0082] In this way, the motor driving device 10 according to the second embodiment can block reverse current flowing through the transistors M5A and M6A, similar to the motor driving device 10 according to the first embodiment.

[0083] 1, the transistors M5B and M6B and the resistors R4 and R5 in Fig. 2 have the same functions as the transistors M5A and M6A and the resistors R1 and R2, respectively. Circuits having the same configurations and functions as the first reverse current blocking circuit 21 and the second reverse current blocking circuit 22 may be connected to the other transistors M5B, M6B, M7, and M8, as in the first embodiment.

[0084] <Motor drive system> Here, a motor drive system using the motor drive device 10 according to this embodiment will be described. As an example of the motor drive system, an unmanned aerial vehicle 30 will be described. The aerial vehicle may be any of a variety of aerial vehicles that fly by driving a motor, such as a drone.

[0085] 3 is a diagram illustrating the overall configuration of a motor drive system according to an embodiment of the present disclosure. The unmanned aerial vehicle 30 includes a motor drive device 10, a motor 11, a propeller 31, a power supply 32, a processor 33, a sensor unit 34, a wireless communication device 35, and an external controller 36. The wireless communication device 35 may include an antenna 35a. The external controller 36 may include an antenna 36a. The power supply 32 may include a power supply circuit 32a and a battery 32b. The unmanned aerial vehicle 30 may include multiple motor drive devices 10, motors 11, and propellers 31.

[0086] The motor driving device 10 drives the motor 11. When the motor 11 is driven, the propeller 31 rotates.

[0087] The power supply 32 includes a power supply circuit 32a and a battery 32b. The power supply 32 supplies a power supply voltage to the motor drive device 10 and the motor 11. The power supply circuit 32a converts power from the battery 32b into power required by the motor drive device 10 and the motor 11. The battery 32b supplies power to the power supply circuit 32a and the processor 33.

[0088] The processor 33 executes functions and methods realized by code or instructions included in a program that controls the unmanned aerial vehicle 30. The processor 33 may include, for example, a CPU (Central Processing Unit), an MPU (Micro Processing Unit), etc., and may realize each process in the unmanned aerial vehicle 30 by a logic circuit (hardware) or dedicated circuit formed on an IC (Integrated Circuit) chip, an LSI (Large Scale Integration), etc.

[0089] The sensor unit 34 includes sensors necessary for controlling the attitude of the unmanned aerial vehicle 30, such as sensors that measure the angular velocity, speed, and surrounding environment of the unmanned aerial vehicle 30, and sensors that measure the status of the motor drive unit 10 and motor 11, etc. Sensors that measure the status of the surrounding environment of the unmanned aerial vehicle 30 include a wind volume sensor, a barometric pressure sensor, a temperature sensor, a humidity sensor, an illuminance sensor, etc. The sensor unit 34 may also include sensors that measure the status of the power source 32, such as the remaining charge of the battery 32b.

[0090] The wireless communication device 35 is a communication circuit that performs transmission and reception processes to transmit and receive signals via a mobile communication network and antenna 35a that supports LTE, NR, etc. The antenna 35a is an antenna for communication via a mobile communication network that supports LTE (Long Term Evolution), NR (New Radio), etc. The antenna 35a is an antenna for communication with an external device, such as a parent aircraft or an aircraft parking facility, that is located in a short distance, for example, with a transmission distance of 10 m or less, using a frequency band of, for example, 2 MHz to 100 MHz.

[0091] The external controller 36 is a controller for controlling the movement of the unmanned aerial vehicle 30. The external controller 36 is configured by a board PC (personal computer) equipped with ROS (Robot Operating System), etc. An antenna 36a connected to the external controller 36 is used for communication with an antenna 35a connected to the wireless communication device 35.

[0092] Although an example has been shown in which the motor drive system according to this embodiment is used as an unmanned aerial vehicle 30, it is not limited to this and can also be used as a power tool, etc.

[0093] Although the embodiments have been described above, they are presented as examples and the present invention is not limited to the above embodiments. The above embodiments can be implemented in various other forms, and various combinations, omissions, substitutions, modifications, etc. can be made without departing from the spirit of the invention. These embodiments and their modifications are included within the scope and spirit of the invention, and are also included in the scope of the invention and its equivalents as set forth in the claims. [Explanation of symbols]

[0094] 10 Motor drive device 11 Motor 20 Motor drive IC 21 1st reverse flow prevention circuit 22 Second reverse flow prevention circuit 23 First ESD protection element 24 Second ESD protection element 25 Drive control unit 30 Unmanned Aerial Vehicles 32 Power supply 41 Control Line 42,43 Gate Line 51 VCC line 52 GND line M1, M2, M3, M4, M5A, M5B, M6A, M6B, M7, M8 transistors

Claims

1. A first terminal; A second terminal; a first transistor for driving a motor, the first transistor having a first electrode connected to the first terminal, a second electrode connected to the second terminal, and a gate connected to a first gate line; a drive control unit that switches the first transistor by controlling a voltage of the gate via the first gate line; a first reverse current blocking circuit that is provided between the first terminal and the first gate line and that blocks communication between the first terminal and the first gate line when a voltage of the first terminal is higher than a voltage of the gate; The motor drive device, wherein the first reverse current blocking circuit turns off the first transistor by connecting the first terminal and the first gate line when the voltage of the first terminal is lower than the voltage of the gate.

2. 2. The motor drive device according to claim 1, further comprising a control line for supplying a control voltage for said first reverse current blocking circuit to said first reverse current blocking circuit.

3. 3. The motor drive device according to claim 2, wherein the first reverse current blocking circuit is configured to block the connection between the first terminal and the first gate line when the control voltage is supplied when the voltage of the first terminal is higher than the voltage of the gate.

4. 4. The motor drive device according to claim 3, wherein the first reverse current blocking circuit adjusts sensitivity for switching between the first terminal and the first gate line from a disconnected state to a connected state in accordance with a voltage value of the control voltage.

5. the first reverse current blocking circuit includes a second transistor and a third transistor, each having a gate connected to the control line; The motor drive device according to claim 2 .

6. The motor drive device according to claim 5 , wherein the second transistor and the third transistor are connected back-to-back.

7. a fourth transistor connected between the second electrode and the back gate of the first transistor; a second gate line connected between the drive control unit and the gate of the fourth transistor, the drive control unit controls a voltage of the gate of the fourth transistor via the second gate line to control a potential of the back gate of the first transistor. The motor drive device according to claim 1 .

8. a second reverse current blocking circuit that is provided between the first terminal and the second gate line and that blocks the connection between the first terminal and the second gate line when a voltage of the first terminal is higher than a voltage of the gate of the fourth transistor; 8. The motor drive device according to claim 7, wherein the second reverse current blocking circuit turns off the fourth transistor by connecting the first terminal and the second gate line when the voltage of the first terminal is lower than the voltage of the gate of the fourth transistor.

9. 9. The motor drive device according to claim 8, further comprising a control line for supplying a control voltage for said second reverse current blocking circuit to said second reverse current blocking circuit.

10. 10. The motor drive device according to claim 9, wherein when the voltage of the first terminal is higher than the voltage of the gate of the fourth transistor, the second reverse current blocking circuit is supplied with the control voltage to cut off the connection between the first terminal and the second gate line.

11. The motor drive device according to claim 10 , wherein the second reverse current blocking circuit adjusts sensitivity for switching between the first terminal and the second gate line from a disconnected state to a connected state in accordance with a voltage value of the control voltage.

12. the second reverse current blocking circuit includes a fifth transistor and a sixth transistor, each having a gate connected to the control line; The motor drive device according to claim 9.

13. The motor drive device according to claim 12 , wherein the fifth transistor and the sixth transistor are connected back-to-back.

14. The motor drive device according to claim 1 , further comprising an ESD protection element connected to the second terminal.

15. The motor drive device according to any one of claims 1 to 13; a motor driven by the motor drive device; a power source electrically connected to the first terminal or the second terminal; A motor drive system comprising:

16. A first terminal; A second terminal; a first transistor for driving a motor, the first transistor having a first electrode connected to the first terminal, a second electrode connected to the second terminal, and a gate connected to a first gate line; a first reverse current blocking circuit that is provided between the first terminal and the first gate line and that blocks communication between the first terminal and the first gate line when a voltage of the first terminal is higher than a voltage of the gate; the first reverse current blocking circuit turns off the first transistor by connecting the first terminal and the first gate line when the voltage of the first terminal is lower than the voltage of the gate.

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