JP2010166668A - Drive unit of brushless motor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To shorten the starting time of a brushless motor, and to reduce energy loss, related to a drive unit which performs an initial setting prior to a forcible drive and an induction drive, when starting the brushless motor. <P>SOLUTION: The drive unit makes a magnet rotor 15 rotate, by sequentially switching energization to each phase coil 14A to 14C of the brushless motor 11; detects the position of the magnet rotor 15, on the basis of induction voltages generated at the coils 14A to 14C; performs the induction drive for controlling energization to the coils 14A to 14C, on the basis of the detected position, performs the initial setting for controlling energization to the coils 14A to 14C, in order to set the magnet rotor 15 to an initial position prior to the induction drive, and after that; performs forced drive for forcibly energizing the coils 14A to 14C, in order to forcibly rotate the magnet rotor 15. Here, the drive unit includes a magnetism-sensing element 21, which detects the vibration of the magnet rotor 15, and forcibly switches the drive to the forcible drive, when the vibration detected by the magnetism sensing element 21 is lowered to a reference value or lower during the initial setting. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a brushless motor driving apparatus that induces and drives a brushless motor by a sensorless driving method.

  Conventionally, as a brushless motor, instead of using a sensor for detecting the magnetic pole position of the magnet rotor, a voltage signal (induced voltage) induced in the stator coil when the magnet rotor rotates is detected, and based on the detected signal 2. Description of the Related Art A sensorless drive type brushless motor that generates a motor energization signal, that is, performs “induced drive” is known. However, the induction voltage is generated in the coil only when the magnet rotor is rotating. When the motor is stopped, the magnet rotor is not rotating. I can't get location information. For this reason, when the motor is started, it is necessary to forcibly energize the stator coil to forcibly rotate the magnet rotor, that is, to perform "forced driving". As an example, Patent Document 1 below describes a brushless motor driving apparatus of a sensorless driving system that performs forced driving at the time of motor startup.

  However, even if forced driving is performed at the time of motor startup, if the phase of the coil to be energized at the time of forced driving is inappropriate, the magnet rotor cannot be forcibly rotated and an induced voltage is generated. The brushless motor cannot be started. In the drive device described in Patent Document 1, first, the coil of a specific phase is energized, and the coil of an appropriate phase is energized after the position of the magnet rotor is determined. However, there are insufficient countermeasures against inactivation due to the position of the initial magnet rotor, and there is a possibility that the motor malfunctions in some cases. For example, when the magnet rotor moves to the target position, it may pass through the target position with excessive momentum, or on the contrary, the forced drive may start before the target position is reached because the movement is too slow. Could not be activated reliably. In addition, if the energization time and the energization timing are inappropriate even during forced driving, the brushless motor cannot be started.

  Here, Patent Document 2 proposes a brushless motor drive device that can activate a brushless motor regardless of the position of the magnet rotor. In this drive device, energization of the coils of each phase is based on duty control, and the magnet rotor is set at a predetermined initial position before forcible drive before induction drive. Therefore, an initial setting for sweeping the energization duty for the coils of each phase is performed. By performing this initial setting, the startup of the brushless motor can be ensured and the stability of the startup time can be ensured.

JP 2004-248387 A JP 2008-301588 A

  However, in the driving device described in Patent Document 2, since it takes some time for the initial setting, the startup time of the brushless motor tends to be longer than that of a normal DC motor. In order to start the brushless motor at an early stage, it is necessary to individually establish an optimal starting method in accordance with the shape and mass of the magnet rotor. Here, at the time of starting, a predetermined time is required until the magnet rotor moves to a predetermined position. The time varies depending on the shape, weight, load, etc. of the magnet rotor and the like, and until the magnet rotor stops at the predetermined position. Since it is necessary to energize the same phase for a long time, it is necessary to find an optimum driving method for each brushless motor in order to realize early start-up. For example, when considering using a brushless motor for a fuel pump for an engine, it is assumed that the optimum starting method varies depending on the shape and weight of the magnet rotor, the viscosity of the fuel, the passage resistance of the fuel line, and the like. . When a brushless motor is used as a fuel pump for an engine, if it takes a long time to start the fuel pump when starting the engine, the fuel pressure rises late and fuel cannot be supplied to the engine quickly. There is a concern of lowering the starting performance. Further, since the failure of starting the brushless motor is directly connected to the inability to start the engine, the situation must be avoided as much as possible, and the starting method must be optimized under the worst conditions. However, when optimization is requested under the worst conditions, there is a concern that it may become an unnecessary startup method in other situations. An unnecessary starting method prolongs the starting time of the brushless motor and leads to energy loss due to energization.

  The present invention has been made in view of the above circumstances, and its object is to reduce the startup time and energy of a brushless motor for a driving device that performs initial setting before forced driving and induction driving when starting the brushless motor. An object of the present invention is to provide a brushless motor drive device that can reduce loss.

  In order to achieve the above object, the invention described in claim 1 is directed to energizing the coils of each phase in a brushless motor including a stator having a plurality of phase coils and a magnet rotor provided corresponding to the stator. The magnet rotor is rotated by sequentially switching, the position of the magnet rotor is detected based on the induced voltage generated in the coils of each phase, and induction driving is performed to control the energization of the coils of each phase based on the detected position, Prior to induction driving, initial setting is performed to control the energization of each phase coil to set the magnet rotor to a predetermined initial position, and then each phase coil is forcibly rotated. In a brushless motor driving apparatus for forcibly driving to energize a magnet rotor, It includes a shaking motion detecting section for detecting a swinging swings detected by the swing detection means during the initial set and spirit to switch to forcibly driven when it becomes less than a predetermined reference value.

  According to the configuration of the above invention, when the brushless motor is started, an initial setting for controlling energization of the coils of each phase is performed in order to set the magnet rotor to a predetermined initial position. Subsequently, in order to forcibly rotate the magnet rotor from the initial position, forcible driving for forcibly energizing each phase coil is performed, and then the position of the magnet rotor is determined based on the induced voltage generated in each phase coil. Is detected, and induction driving is performed to control energization of the coils of each phase based on the detected position. In this way, the brushless motor is started by sequentially switching from the initial set to forced drive and induced drive. Here, the energization of the initial set is performed, so that the magnet rotor starts to move toward the initial position with swinging from the stopped state. The swinging at this time gradually converges in the process in which the magnet rotor approaches the initial position. Further, it has been found that the magnet rotor can stop at the initial position when the swing of the magnet rotor is below a certain magnitude. According to the configuration of the present invention, when the swing of the magnet rotor detected by the swing detection means becomes equal to or less than the predetermined reference value during the initial set, the initial set is switched to the forced drive. Therefore, the magnet rotor that has started to move with swinging by the initial setting is forcibly rotated by forced driving shortly before the swinging stops at the initial position.

  In order to achieve the above object, according to a second aspect of the present invention, in the first aspect of the present invention, the oscillation detecting means is a magnetic sensitive element disposed in the vicinity of the magnet rotor. The purpose is to detect the swing of the magnet rotor based on the output.

  According to the configuration of the above invention, in addition to the operation of the invention described in claim 1, the magnetosensitive element outputs the change of the magnetic field of the magnet rotor as the swing of the magnet rotor.

  In order to achieve the above object, according to a third aspect of the present invention, in the first aspect of the present invention, the oscillation detecting means is a coil of each phase, and is based on a change amount of a magnetic field generated in the coil of each phase. The purpose is to detect the swing of the magnet rotor.

  According to the configuration of the above invention, in addition to the operation of the invention described in claim 1, it is not necessary to provide a separate sensor or the like in order to detect the swing of the magnet rotor.

  In order to achieve the above object, according to a fourth aspect of the present invention, in the invention according to any one of the first to third aspects, energization of the coils of each phase is based on duty control, and The purpose of this is to carry out the energization for the maximum value.

  According to the configuration of the invention, in addition to the operation of the invention according to any one of claims 1 to 3, since energization is performed at the maximum constant value from the beginning in the initial setting, from the beginning of the initial setting. Maximum torque is applied to the magnet rotor.

  In order to achieve the above object, according to a fifth aspect of the present invention, in the invention according to any one of the first to third aspects, energization of the coils of each phase is based on duty control, and the initial set is The purpose is to include a portion for conducting energization to a predetermined value and a portion for performing the current without sweeping by a predetermined value.

  According to the configuration of the above invention, in addition to the operation of the invention according to any one of claims 1 to 3, in the initial setting, the torque applied to the magnet rotor is moderated at a portion where the energization is swept to a predetermined value. The torque that does not change is applied to the magnet rotor in the portion where the energization is performed without sweeping the current by a predetermined value.

  In order to achieve the above object, according to a sixth aspect of the present invention, in the invention according to any one of the first to third aspects, energization of the coils of each phase is based on duty control, and an initial set is set. The purpose is that the energization for the initial set is performed twice, the energization for the initial set is performed at a maximum constant value, and the energization time for the first initial set is set shorter than that of the second initial set.

  According to the configuration of the invention, in addition to the operation of the invention according to any one of claims 1 to 3, in the first initial set, energization with a maximum constant value is performed in a short energization time. Maximum torque is instantaneously applied to the magnet rotor. In the second initial set, energization with the maximum constant value is performed for a longer energization time than in the first time. Therefore, in the second initial set, the maximum torque is applied to the magnet rotor longer.

  In order to achieve the above object, according to a seventh aspect of the present invention, in the invention according to any one of the first to third aspects, energization of the coils of each phase is based on duty control, and an initial set is set. Perform at least twice, the first initial set without energization sweeping by a predetermined value, and the second initial set including a part for energization sweeping to a predetermined value and a part for performing energization without sweeping by a predetermined value The purpose.

  According to the configuration of the invention, in addition to the operation of the invention according to any one of claims 1 to 3, in the first initial set, energization is performed without sweeping by a predetermined value. In particular, it is applied to the magnet rotor. In the second initial set, the torque applied to the magnet rotor gradually increases in the part where the energization is swept to a predetermined value, and the torque that does not change is applied to the magnet rotor in the part where the energization is not swept by the predetermined value. Is granted.

  According to the first aspect of the present invention, the startup time of the brushless motor can be shortened and the energy loss can be reduced for the drive device that performs the initial setting before the forced drive and induction drive when starting the brushless motor. Can do.

  According to the second aspect of the invention, in addition to the effect of the first aspect of the invention, the swing of the magnet rotor can be detected in a non-contact manner, and durability and maintainability as a sensor for detecting the swing. Excellent.

  According to the invention described in claim 3, in addition to the effect of the invention described in claim 1, the configuration can be simplified.

  According to the invention described in claim 4, in addition to the effect of the invention described in any one of claims 1 to 3, the magnet rotor can be rotated as quickly as possible by the initial setting. Contributes to shortening of motor start-up time.

  According to the invention described in claim 5, in addition to the effect of the invention described in any one of claims 1 to 3, the magnet rotor can be set in a state where it can be forcibly driven more reliably.

  According to the invention described in claim 6, in addition to the effect of the invention described in any one of claims 1 to 3, it is possible to create a starting point for the movement of the magnet rotor by the first initial setting, With the second initial setting, the magnet rotor can be quickly set to the initial position with the maximum torque, and the magnet rotor can be reliably set to a state where it can be forcibly driven. In addition, since the initial setting is performed twice in succession, even if the energization by the first initial set fails, the magnet rotor does not stop at the dead point by the second energization of the initial set.

  According to the invention described in claim 7, in addition to the effect of the invention described in any one of claims 1 to 3, the magnet rotor can be set in a state where it can be forcibly driven more reliably. In addition, since the initial setting is performed twice in succession, even if the energization of the first initial set fails, the magnet rotor does not stop at the dead point by the energization of the second initial set.

1 is a schematic configuration diagram illustrating an engine system according to a first embodiment. Similarly, the electric circuit diagram which shows the structure of a brushless motor and its controller. Similarly, the time chart which shows each phase electricity supply timing at the time of induction drive, and each phase coil terminal voltage change. Similarly, the time chart which shows the change of the coil terminal voltage of each phase at the time of normal rotation of a magnet rotor. Similarly, (A)-(F) is a conceptual diagram which shows all the relations which can be considered about the positional relationship of the stator and magnet rotor in a motor stop state. Similarly, the flowchart which shows the control logic which a control circuit performs. Similarly, the time chart which shows the change of the output voltage of a magnetosensitive element. Similarly, the time chart which shows the change of the electricity supply duty value with respect to the coil of each phase, and the change of a rotor rocking | fluctuation value. Similarly, the flowchart which shows the change of the energization phase corresponding to the control logic shown in FIG. Similarly, the conceptual diagram which shows the change of the energization phase with the flow of control logic, and the change of the positional relationship of a stator and a magnet rotor. The time chart which shows the change of the energization duty value with respect to the coil of each phase, and the change of a rotor rocking | fluctuation value concerning 2nd Embodiment. The time chart which concerns on 3rd Embodiment and shows the change of the electricity supply duty value with respect to the coil of each phase, and the change of a rotor rocking | fluctuation value. The time chart which concerns on 4th Embodiment and shows the change of the electricity supply duty value with respect to the coil of each phase, and the change of a rotor rocking | fluctuation value. The time chart which shows the change of the coil terminal voltage of each phase in 2nd time of an initial set concerning 5th Embodiment.

[First Embodiment]
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A detailed description of a first embodiment of a brushless motor driving apparatus according to the present invention will be given below with reference to the drawings.

  In this embodiment, the present invention will be described with a sensorless type brushless motor driving device used for a fuel pump of an automobile engine. FIG. 1 is a schematic configuration diagram showing an engine system. The engine 41 constituting the engine system includes an intake passage 43 that introduces outside air into the combustion chamber 42 and an exhaust passage 44 that guides exhaust gas from the combustion chamber 42 to the outside. The intake passage 43 is provided with an injector 45 for injecting fuel. The engine 41 is provided with a spark plug 46. The spark plug 46 is ignited by receiving a high voltage from the igniter 47.

  The engine system includes a fuel supply device 48 that supplies fuel to the combustion chamber 42. In addition to the injector 45, the fuel supply device 48 includes a fuel tank 49 that stores fuel, a fuel pump unit 50 that is accommodated in the fuel tank 49, and a fuel line 51 that sends fuel from the fuel pump unit 50 to the injector 45. Prepare. The fuel pump unit 50 includes a fuel pump 52, a high-pressure filter 53, and the like. By operating the fuel pump 52, the fuel in the fuel tank 49 is pumped to the injector 45 through the fuel line 51. The fuel pumped to the injector 45 is injected into the intake passage 43 when the injector 45 operates. The injected fuel forms an air-fuel mixture with the air sucked into the intake passage 43 and is introduced into the combustion chamber 42. This air-fuel mixture explodes and burns when the ignition plug 46 operates in the combustion chamber 42. The exhaust gas after combustion is discharged to the outside through the exhaust passage 44. In such a series of strokes, the piston 54 moves up and down and the crankshaft (not shown) rotates, whereby power is obtained for the engine 41.

  The intake passage 43 is provided with an electronic slot device 55 that adjusts the intake air amount. An intake air temperature sensor 61 and an intake pressure sensor 62 are provided in the intake passage 43. The engine 41 is provided with a water temperature sensor 63 and a rotation speed sensor 64. The driver seat is provided with an accelerator sensor 65 corresponding to the accelerator pedal 56. The driver's seat is provided with an ignition switch (IG switch) 66 for operating the start of the engine 41. The engine system further includes an electronic control unit (ECU) 70 that controls the operation of the engine 41. The ECU 70 performs an injector 45, an igniter 47, a fuel pump 52, an electronic slot, and the like in order to execute fuel supply control and ignition timing control according to the operating state of the engine 41 based on detection signals from various sensors 61-66. Each of the devices 55 is controlled.

  A fuel pump unit 50 is provided in the fuel tank 49 to store fuel. A controller 10 for the fuel pump 52 is provided outside the upper portion of the fuel tank 49. The fuel pump 52 includes a brushless motor 11 and an impeller that is rotationally driven by the motor 11. The controller 10 controls the fuel pump 52 by controlling the brushless motor 11. The ECU 70 exchanges signals with the controller 10 in order to control the fuel pump 52 in accordance with the operation of the engine 41.

  Next, the brushless motor 11 and its driving device will be described in detail in connection with the fuel pump 52 described above. FIG. 2 is an electric circuit diagram showing the configuration of the brushless motor 11 and its controller 10. The controller 10 includes a control circuit 12 and a drive circuit 13. In this embodiment, the brushless motor 11 is a three-phase, four-pole sensorless type, and a three-phase full-wave drive system circuit is employed for the drive circuit 13. The brushless motor 11 includes a stator 14 including three-phase (U-phase, V-phase, and W-phase) coils 14A, 14B, and 14C, and a four-pole magnet rotor 15. Since the brushless motor 11 is of a sensorless type, it is generated in the coils 14A to 14C of each phase of the stator 14 without using a Hall element in order to detect the magnetic pole position (rotor position) of the magnet rotor 15 with respect to the stator 14. An induced voltage is used. Then, when the magnet rotor 15 rotates, the rotor position is detected based on the induced voltage generated in the coils 14A to 14C of each phase, and the coil 14A of each phase to be energized based on the detected rotor position. “Induced drive” is performed to determine ˜14C.

  As shown in FIG. 2, the drive circuit 13 includes PNP-type first, third, and fifth transistors Tr1, Tr3, and Tr5 as switching elements, and NPN-type second, fourth, and sixth transistors. Each of Tr2, Tr4, and Tr6 is configured by a three-phase bridge connection. The emitters of the first, third, and fifth transistors Tr1, Tr3, Tr5 are each connected to a power supply (+ B), and the emitters of the second, fourth, and sixth transistors Tr2, Tr4, Tr6 are grounded. One terminal of the coils 14A to 14C of each phase of the brushless motor 11 is connected to a common connection point, the other terminals are common connection points of the first and second transistors Tr1 and Tr2, and the third and fourth transistors Tr3. , Tr4, and the common connection point of the fifth and sixth transistors Tr5, Tr6, respectively. The bases of the transistors Tr1 to Tr6 are connected to the control circuit 12. Both terminals of the control circuit 12 are connected to the power source (+ B) and grounded. In this embodiment, the control circuit 12 is configured by a custom IC.

  In addition, in this embodiment, the magnetosensitive element 21 constituting the swing detection means of the present invention for detecting the swing of the magnet rotor 15 is disposed in the vicinity of the magnet rotor 15. The magnetic sensing element 21 detects a change in the magnetic field of the magnet rotor 15 as the swing of the magnet rotor 15. As the magnetic sensing element 21, for example, a Hall element or an MRE sensor can be used. The magnetosensitive element 21 is connected to the control circuit 12.

  Since the brushless motor 11 of this embodiment is a sensorless type, no induced voltage is generated in the coils 14A to 14C of each phase when stopped. Therefore, in this embodiment, when the brushless motor 11 is started, the magnet rotor 15 is rotated by forcibly energizing the two-phase coils among the three-phase coils 14A to 14C in a predetermined energization sequence. "Forced drive" is performed. However, the magnet rotor 15 may or may not rotate even when the energization of the coils 14A to 14C of each phase is forcibly started in a predetermined energization sequence while ignoring the rotor position at the time of startup. For this reason, the brushless motor 11 may be activated, may not be activated, or may take longer than necessary to complete activation. Therefore, in this embodiment, when the brushless motor 11 is started, predetermined “startup control” is executed to energize the coils 14 </ b> A to 14 </ b> C of each phase and start the brushless motor 11. After the desired induced voltage is generated by this “startup control”, the operation is switched to the “induced drive” described above.

  Here, the “induced drive” will be described in detail. FIG. 3 is a time chart showing each phase energization timing and each phase coil terminal voltage change executed by the control circuit 12 during induction driving. The control circuit 12 controls energization of the U-phase, V-phase, and W-phase coils 14A to 14C by controlling energization of the bases (gates) of the transistors Tr1 to Tr6 of the drive circuit 13. In FIG. 3, “UH, VH, and WH” indicate Hi-side gates that set the U phase, V phase, and W phase to high levels, and “UL, VL, and WL” indicate U phase, V phase, and W phase, respectively. A low-side gate that is at a low level is shown. As shown in FIG. 3, by controlling the energization of the Hi-side gate and the Low-side gate, the U-phase, V-phase, and W-phase coils 14A to 14C are energized, and a coil terminal voltage is generated in each phase. I understand.

  FIG. 4 is a time chart showing changes in the terminal voltages of the coils 14A to 14C of the U phase, V phase, and W phase when the magnet rotor 15 is rotating normally. As can be seen from this chart, the coils 14A to 14C of each phase receive “120 ° energization” and “60 ° non-energization” alternately. In FIG. 4, when switching to non-energization at time t <b> 1, a positive counter electromotive force is first generated as a pulsed voltage, and then the induced voltage increases. Next, a transition is made by a positive constant voltage from when switching to energization at time t2 to when switching to non-energization at time t3. And when it switches to a non-energization at the time t3, a negative counter electromotive force will arise as a pulse-like voltage, and an induced voltage will reduce after that. And when it switches to electricity supply at the time t4, it changes with a negative constant voltage. The control circuit 12 detects the rotor position using an induced voltage generated after the back electromotive voltage. The control circuit 12 controls energization of the coils 14A to 14C of the U-phase, V-phase, and W-phase based on the rotor position detected as described above. That is, the control circuit 12 rotates the magnet rotor 15 by sequentially switching energization to the coils 14A to 14C of each phase, and detects the rotor position based on the induced voltage generated in the coils 14A to 14C of each phase. And the control circuit 12 controls electricity supply with respect to the coils 14A-14C of each phase based on the detected rotor position. In this way, “induced driving” is performed.

  Here, FIGS. 5A to 5F are conceptual diagrams showing all possible relations regarding the positional relation between the stator 14 and the magnet rotor 15 in the motor stopped state. When the stop position (initial position) of the magnet rotor 15 with respect to the stator 14 before starting is convenient for starting the brushless motor 11, for example, “U → V”, “U → W”, “V → W”, “ The brushless motor 11 can be driven by switching the energization phase in a predetermined energization sequence of “V → U”, “W → U”, and “W → V”. The positional relationships in FIGS. 5A to 5D correspond to this convenient case. On the other hand, when the stop position (initial position) of the magnet rotor 15 with respect to the stator 14 before activation is inconvenient for the activation of the brushless motor 11, the brushless motor 11 is switched even if the energization phase is switched in the predetermined energization sequence described above. It cannot be driven. The positional relationship shown in FIGS. 5E and 5F corresponds to this inconvenient case. As described above, depending on the initial position of the magnet rotor 15, the brushless motor 11 may or may not be activated, and conventionally, the brushless motor cannot be reliably activated.

  Therefore, in this embodiment, in order to cope with the case where the stop position of the magnet rotor 15 is inconvenient for the activation of the brushless motor 11, the magnet rotor 15 is moved by “initial setting” and “forced driving” when the brushless motor 11 is activated. It is designed to rotate. After the induced voltage is generated by “forced driving”, the operation is switched to “induced driving” performed by detecting the induced voltage.

  FIG. 6 is a flowchart showing the control logic executed by the control circuit 12. FIG. 7 is a time chart showing changes in the output voltage of the magnetosensitive element 21. FIG. 8 is a time chart showing changes in the energization duty value DY for the coils 14A to 14C of each phase and changes in the rotor swing value.

  In this control logic, first, in step 100, when the ignition switch (IG switch) 66 of the engine 41 is turned on and an activation signal is input, in step 110, the control circuit 12 executes an initial set. That is, the control circuit 12 energizes the coils 14A to 14C of each phase based on a predetermined energization duty value DY. As shown in FIG. 8A between the times t0 and t1, in this embodiment, the control circuit 12 performs the “max control”, that is, the energization duty value DY is set to the maximum constant value, and the initial setting is performed. Energized. As this maximum constant value, for example, “60%” can be applied.

  Next, at step 120, the control circuit 12 monitors the rotor swing value. That is, the control circuit 12 detects and monitors the swing value of the magnet rotor 15 based on the output voltage of the magnetosensitive element 21.

  Here, in the initial setting, when a voltage is applied to the coils 14A to 14C of a specific phase by energization, the magnet rotor 15 starts to rotate toward a predetermined initial position with swinging from a stopped state. However, it takes a certain amount of time for the magnet rotor 15 to reach a predetermined initial position. The swing at this time gradually converges while the magnet rotor 15 approaches the initial position, and the magnet rotor 15 stops rotating while swinging. Further, it has been found that the magnet rotor 15 can be stopped at the initial position when the swing of the magnet rotor 15 is below a certain magnitude. The magnitude of the swing may vary depending on differences in the shape and weight of the magnet rotor 15, the viscosity of the fuel pumped out by the fuel pump 52, the passage resistance of the fuel line 51, and the like. Here, the magnetosensitive element 21 outputs a voltage in response to a change in the magnetic field due to the swing of the magnet rotor 15. As shown in FIG. 7, the output voltage gradually converges while oscillating in accordance with the change in oscillation of the magnet rotor 15. In this embodiment, the value of the output voltage as shown in FIG. 7 is sampled every certain period, and the fluctuation value is monitored by calculating the fluctuation range of the voltage from the change of the output voltage. As a method of calculating the fluctuation range of the output voltage, the output voltage of the magnetosensitive element 21 is AD-converted with a short period (for example, “1 ms”) shown in FIG. 7, and the current AD conversion value and the previous AD The change amount and change direction with respect to the conversion value are obtained sequentially. Then, the maximum value Vmax and the minimum value Vmin of the output voltage are sequentially obtained from the change amount and the change direction, and the output voltage is calculated from the difference between the current maximum value Vmax or the minimum value Vmin and the previous minimum value Vmin or the maximum value Vmax. The fluctuation range Vw is calculated, and the fluctuation range Vw is obtained as the swing value of the magnet rotor 15 (rotor swing value). FIG. 8B shows the change in the rotor swing value.

In step 130, the control circuit 12 determines whether or not the monitored rotor swing value is equal to or less than a predetermined reference value Fw. That is, as shown in FIG. 8B, it is determined whether or not the vibration width of the rotor swing value is equal to or less than a predetermined reference value Fw. Here, it is known that if energization is switched to the coils 14 </ b> A to 14 </ b> C of the next phase while the magnet rotor 15 is swinging, the step-out occurs and the start of the brushless motor 11 becomes unstable. For this reason, in order to achieve stable start-up, it is necessary to establish a driving method in a state in which the rocking lasts the longest in consideration of various worst conditions. However, in that case, energy loss is caused by energizing wastefully under the best conditions. Therefore, in this embodiment, the rotor swing value is monitored by using the magnetosensitive element 21, the position of the magnet rotor 15 is determined in an optimum time, and the coils 14A to 14C of the next phase are forcibly driven. Is energized. The predetermined reference value Fw is set as a value that can satisfy the above request. If the determination result of step 130 is negative, the control circuit 12 returns the process to step 110 to continue monitoring the rotor swing value. If the determination result is affirmative, the control circuit 12 proceeds to step 140 assuming that the magnet rotor 15 reaches a predetermined initial position.

  In step 140, the control circuit 12 executes “forced driving”. That is, as shown in FIG. 8 (A) after time t1, the energization duty value DY is set to a predetermined constant value (in this embodiment, “30%”), and the magnet rotor 15 has reached a predetermined initial position. As described above, the brushless motor 11 is forcibly driven by switching the energized phases in a predetermined energization order with respect to the coils 14A to 14C of the respective phases.

  Thereafter, in step 150, the control circuit 12 performs position detection of the magnet rotor 15 by monitoring the induced voltage. Thereafter, in step 160, the control circuit 12 determines whether or not the position of the magnet rotor 15 has been detected. If the position cannot be detected by this determination, the control circuit 12 returns to step 140 forcibly driving again.

  On the other hand, if the position can be detected based on the determination in step 160, the control circuit 12 executes “induction driving” in step 170, and the process returns to monitoring of the induced voltage in step 150.

  That is, in this embodiment, before performing “forced driving” and “inductive driving”, initial setting, which is energization for setting the magnet rotor 15 to a predetermined initial position, is performed. This energization is performed by max control in which the energization duty value DY is a maximum constant value.

  FIG. 9 is a flowchart showing changes in the energized phase corresponding to the control logic shown in FIG. In this embodiment, in the initial set, energization is performed from the W phase to the U phase, that is, from the coil 14C to the coil 14A. Next, in the forced drive, power is supplied from the W phase to the V phase, that is, from the coil 14C to the coil 14B. In the subsequent forced drive or induction drive, “U → V”, “U → W”, “V → W” , “V → W”,..., “U → V”, and the coils 14A to 14C of each phase are energized in the order and direction.

  Here, the positional relationship between the stator 14 including the phases U, V, and W from the initial set to the execution of forced driving or induction driving and the magnet rotor 15 will be described. FIG. 10 is a conceptual diagram showing changes in the energized phase accompanying the flow of the control logic and changes in the positional relationship between the stator 14 and the magnet rotor 15. When the initial setting is performed from the motor stop state shown in FIGS. 5A to 5F, the magnet rotor 15 starts to rotate instantaneously and becomes the state shown in FIG. Thereafter, the forced driving is performed, whereby the magnet rotor 15 is further rotated by 30 ° to be in the state shown in FIG. Thereafter, the forced driving is performed, whereby the magnet rotor 15 is further rotated by 30 ° to be in the state shown in FIG. Thereafter, forced driving or induction driving is performed, so that the magnet rotor 15 is further sequentially rotated by 30 ° to be in the state shown in FIGS. 10 (D) and 10 (E).

  According to the brushless motor driving apparatus in this embodiment described above, the magnet rotor 15 is set at a predetermined initial position before the engine 41 is started, that is, when the brushless motor 11 is started, before the forced driving and induction driving are performed. In order to do so, an initial set for controlling energization of the coils 14A to 14C of each phase is performed. Subsequently, in order to forcibly rotate the magnet rotor 15 from the initial position, forcible driving for forcibly energizing the coils 14A to 14C of each phase is performed, and then the induced voltage generated in the coils 14A to 14C of each phase. Is detected, and the induction drive is performed to control the energization of the coils 14A to 14C of each phase based on the detected position. In this way, the brushless motor 11 is started by sequentially switching from the initial set to forced driving and induction driving.

  Here, when energization of the initial set is performed, the magnet rotor 15 starts to rotate from the stopped state toward the initial position with swinging. The swing at this time gradually converges in the process in which the magnet rotor 15 approaches the initial position. Further, it has been found that the magnet rotor 15 can be stopped at the initial position when the swing of the magnet rotor 15 is below a certain magnitude. In this embodiment, the swing of the magnet rotor 15 is detected by the magnetosensitive element 21 during the initial setting, and the detected rotor swing value becomes equal to or less than a predetermined reference value Fw as shown in FIG. At time (time t1), the initial set is switched to the forced drive. Therefore, the magnet rotor 15 that has started to move with swinging by the initial setting is forcibly rotated by forced driving slightly before the swinging stops at the initial position. Conventionally, as shown by a broken line in FIG. 8A, the initial set is switched to the forced drive at the time t2 when the rotor swing value approaches almost zero. For this reason, in this embodiment, the startup time of the brushless motor 11 can be shortened by the amount of switching from the initial set to the forced drive slightly before the oscillation of the magnet rotor 15 is completely stopped. Energy loss can be reduced. Further, when the engine 41 is started in this manner, the brushless motor 11 starts to start quickly, so that the discharge pressure of the fuel pump 52 quickly increases. As a result, when the engine 41 is started, the amount of fuel supplied to the engine 41 can be quickly increased, and the startability of the engine 41 can be improved. This also contributes to an improvement in exhaust emission when the engine 41 is started.

  In this embodiment, the magnetosensitive element 21 is used to detect the swing of the magnet rotor 15. Here, the magnetosensitive element 21 outputs the change in the magnetic field of the magnet rotor 15 as the swing of the magnet rotor 15. Therefore, the swing of the magnet rotor 15 can be detected in a non-contact manner, and the durability and maintainability are excellent as a sensor for detecting the swing.

  In this embodiment, as shown in FIG. 8A, energization with a maximum constant value is performed from the beginning in the initial setting, so that the maximum torque is applied to the magnet rotor 15 from the beginning of the initial setting. . For this reason, the magnet rotor 15 can be rotated as quickly as possible by the initial setting, which contributes to shortening of the startup time of the brushless motor 11.

  In this embodiment, since the energization of the coils 14A to 14C of each phase is performed by the three-phase full-wave drive method, the magnet rotor 15 can be efficiently and forcibly driven with the stator 14 by performing the above-described initial setting. Positional relationship. For this reason, especially as the three-phase brushless motor 11, it can be made into the state which can be started efficiently.

  In this embodiment, after the initial setting is performed, that is, after the magnet rotor 15 is set at a predetermined initial position, the forcible driving is performed before the induction driving is performed, and the magnet rotor 15 starts to start reliably. For this reason, the brushless motor 11 can be reliably started before performing induction driving. The energization duty value DY for a certain period until the rotation of the magnet rotor 15 is stabilized is set to a predetermined value (in this case, “30%”) by forced driving. Accordingly, the starting momentum of the magnet rotor 15 is moderately suppressed, and the magnet rotor 15 does not rotate past a predetermined initial position. For this reason, the step-out of the magnet rotor 15 at the time of starting can be prevented.

[Second Embodiment]
Next, a second embodiment of the brushless motor driving device according to the present invention will be described in detail with reference to the drawings.

  In the following description, the same components as those in the first embodiment are denoted by the same reference numerals, description thereof is omitted, and different points are mainly described.

  This embodiment differs from the first embodiment in terms of the contents of the initial set. FIG. 11 is a time chart showing changes in the energization duty value DY for the coils 14A to 14C of each phase and changes in the rotor swing value. In this embodiment, although the initial setting is performed once as in the first embodiment, the configuration includes the part for sweeping energization (sweep control) and the part for not sweeping (holding control). Is different. That is, in this embodiment, as shown at times t0 to t1 in FIG. 11, the energization duty value DY is gradually increased from a short time (small energization ratio) to a long time (large energization ratio) to a maximum constant value. “Sweep control” is performed, and thereafter “holding control” is performed to hold the energization duty value DY at a maximum constant value, as shown at times t1 to t2 in FIG.

  Therefore, in this embodiment, in the initial setting, according to the sweep control that sweeps the energization, the torque applied to the magnet rotor 15 increases gently, and according to the holding control that does not sweep the energization, the torque that does not change is the magnet rotor. 15 is given. Thereby, the magnet rotor 15 moves slowly and surely and is set at a predetermined initial position. As a result, the magnet rotor 15 can be set in a state where it can be forcibly driven more reliably.

[Third Embodiment]
Next, a third embodiment of the brushless motor driving device according to the present invention will be described in detail with reference to the drawings.

  This embodiment is different from the first and second embodiments in terms of the contents of the initial set. FIG. 12 is a time chart showing changes in energization duty value DY and rotor swing values for coils 14A to 14C of each phase. In this embodiment, unlike the first and second embodiments, the initial setting is performed twice, and the energization for the two initial setting is performed at the maximum constant value, and the second initial setting is performed. Compared to, the energization time for the first initial setting is set shorter. That is, in this embodiment, as shown at times t0 to t1 in FIG. 12, energization is performed to instantaneously set the energization duty value DY to a maximum constant value, and thereafter, at times t2 to t3 in FIG. In this way, “holding control” is performed to hold the energization duty value DY at a maximum constant value.

  Therefore, according to this embodiment, in the first initial set, energization with the maximum constant value is performed in a short energization time, so that the maximum torque is instantaneously applied to the magnet rotor 15. Further, in the second initial set, energization with the maximum constant value is performed for a longer energization time than in the first time, so in the second initial set, the maximum torque is applied to the magnet rotor 15 in a long time. The For this reason, the movement of the magnet rotor 15 can be made by the first initial setting. Thereafter, by the second initial setting, the magnet rotor 15 can be quickly set to the initial position with the maximum torque, and the magnet rotor 15 can be reliably set in a state where it can be forcibly driven. In this embodiment, since the initial setting is performed twice in succession, even if the energization by the first initial setting fails, the magnet rotor 15 is set to the “dead point” by the second initial setting energization. It never stops.

[Fourth Embodiment]
Next, a fourth embodiment in which the brushless motor driving device according to the present invention is embodied will be described in detail with reference to the drawings.

  This embodiment differs from the third embodiment in terms of the contents of the initial set. FIG. 13 is a time chart showing changes in the energization duty value DY for the coils 14A to 14C of each phase and changes in the rotor swing value. In this embodiment, the initial setting is performed twice as in the third embodiment, but the first initial setting is performed without sweeping the energization with the maximum constant value, and the second initial setting is performed with the maximum energization. A part to be swept up to a certain constant value (sweep control) and a part to be swept without the maximum constant value (holding control) are included. That is, in this embodiment, as shown at times t0 to t1 in FIG. 13, energization is performed to instantaneously set the energization duty value DY to a maximum constant value, and thereafter, at times t2 to t3 in FIG. Thus, sweep control and holding control are performed.

  Therefore, according to this embodiment, since energization with the maximum constant value is performed in a short energization time by the first initial setting, torque is instantaneously applied to the magnet rotor 15. Subsequently, with the initial setting for the second time, in the sweep control, the torque applied to the magnet rotor 15 gradually increases, and in the holding control, a torque that does not change is continuously applied to the magnet rotor 15. Thereby, the magnet rotor 15 moves reliably after the first initial setting and is set at a predetermined initial position. As a result, the magnet rotor 15 can be set in a state where it can be forcibly driven more reliably. In this embodiment, since the initial setting is performed twice in succession, even if the energization of the first initial set fails, the magnet rotor 15 becomes the “dead point” by the energization of the second initial set. It never stops.

[Fifth Embodiment]
Next, a fifth embodiment of the brushless motor driving device according to the present invention will be described in detail with reference to the drawings.

  This embodiment is different from the above embodiments in terms of the swing detection means for detecting the swing of the magnet rotor 15. In this embodiment, each phase coil 14A to 14C constituting the stator 14 constitutes the swing detection means of the present invention. Based on the amount of change in the magnetic field generated in each phase coil 14A to 14C, the magnet rotor 15 swings. It is designed to detect movement. FIG. 14 is a time chart showing changes in terminal voltages of the coils 14A to 14C in each phase of the U phase, the V phase, and the W phase in the second initial set. The waveform of this terminal voltage is different from the waveform when the magnet rotor 15 is normally rotated by induction driving shown in FIG. That is, as shown in FIG. 14, in the second initial set, when switching to non-energization at time t1, a positive counter electromotive force is first generated as a pulsed voltage, and then induced between times t2 and t4. A voltage is generated. At this time, between times t2 and t3, the magnet rotor 15 swings to start moving, so that the induced voltage shows a vibration waveform centered on a value of “+ B · 1/2”, and thereafter, from time t3 to time t3. During t4, the magnet rotor 15 is stopped, so that the induced voltage becomes constant at a value of “+ B · 1/2”. Next, during the period from switching to energization at time t4 to switching to non-energization at time t5, the voltage changes with a positive constant voltage. And when it switches to a non-energization at the time t5, a negative back electromotive force will arise as a pulse-like voltage, and an induced voltage will arise after that from the time t5-t7. At this time, between time t6 and time t7, the induced voltage becomes constant at a value of “+ B · 1/2” because the magnet rotor 15 is stopped. In this embodiment, when the induced voltage becomes a value within the range of “+ B · 3/7 to + B · 4/7” centering on “+ B · 1/2”, the control device 12 causes the magnet rotor 15 to It is determined that it is stopped. The control device 12 starts “forced driving” when it is determined that the magnet rotor 15 is stopped based on the induced voltage.

  Therefore, according to this embodiment, the fluctuation of the magnetic rotor 15 can be detected based on the change of the magnetic field generated in the coils 14A to 14C of each phase, that is, the waveform of the induced voltage. There is no need to provide a separate sensor or the like. For this reason, a structure can be simplified as a drive device for the brushless motor 11.

  In addition, the operational effects of the configuration common to the first embodiment are basically the same as those of the first embodiment.

  Note that the present invention is not limited to the above-described embodiments, and can be implemented as follows by appropriately changing a part of the configuration without departing from the spirit of the invention.

  For example, in each of the above embodiments, the driving device of the present invention is embodied in the three-phase brushless motor 11, but may be appropriately embodied in a brassless motor having a number of phases other than three phases.

  The present invention can be used for a fluid pump, in particular, a fuel pump for supplying fuel to an automobile engine.

10 Controller 11 Brushless motor 12 Control circuit 14 Stator 14A Coil (swing detection means)
14B Coil (swing detection means)
14C coil (swing detection means)
15 Magnet rotor 21 Magnetosensitive element (swing detection means)

Claims (7)

For a brushless motor including a stator having a plurality of phase coils and a magnet rotor provided corresponding to the stator, the magnet rotor is rotated by sequentially switching energization to the coils of each phase, and each phase is The position of the magnet rotor is detected based on the induced voltage generated in the coil of the magnet, and the induction drive is performed based on the detected position to control the energization of the coils of each phase. Perform initial setting to control energization of each phase coil to set the rotor at a predetermined initial position, and then forcibly energize each phase coil to forcibly rotate the magnet rotor. In a brushless motor drive device that performs forced drive,
A swing detecting means for detecting the swing of the magnet rotor is provided, and the forced drive is switched to when the swing detected by the swing detecting means during the initial setting falls below a predetermined reference value. A drive device for a brushless motor. The swing detection means is a magnetosensitive element arranged in the vicinity of the magnet rotor, and detects the swing of the magnet rotor based on an output of the magnetosensitive element. Brushless motor drive device. 2. The brushless according to claim 1, wherein the swing detection unit is a coil of each phase, and detects swing of the magnet rotor based on a change amount of a magnetic field generated in the coil of each phase. Motor drive device. 4. The brushless motor according to claim 1, wherein energization of the coils of each phase is based on duty control, and energization for the initial setting is performed at a maximum constant value. 5. Drive device. The energization of the coils of each phase is based on duty control, and the initial set includes a portion where the energization is swept up to a predetermined value and a portion where the energization is not swept according to the predetermined value. The brushless motor drive device according to any one of the above. The energization of the coils of each phase is based on duty control, the initial setting is performed twice, the energization for the initial setting is performed at the maximum constant value, and the first time compared to the second initial setting. 4. The brushless motor driving device according to claim 1, wherein the energization time for the initial setting is set short. The energization of the coils of each phase is due to duty control, the initial set is performed at least twice, the first initial set is performed without sweeping the energization by a predetermined value, and the second initial set is energized. 4. The brushless motor driving device according to claim 1, further comprising a portion that sweeps to a predetermined value and a portion that does not sweep by the predetermined value.

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