JP3389328B2 - Motor starter - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a motor starting device for starting a three-phase sensorless brushless motor having three sets of armature coils connected to a neutral point and non-grounded Y connection. About. 2. Description of the Related Art In general, a sensorless brushless motor (hereinafter simply referred to as a motor) does not include a rotor position detecting sensor such as a Hall element. Unless a predetermined induced voltage is generated in the non-energized armature coil, the position of the rotor cannot be detected. Therefore, for example, as disclosed in Japanese Patent Application Laid-Open No. 1-30819 (a method of starting a sensorless brushless motor), an armature coil of a motor is excited to an initial setting state for a predetermined time, and thereafter, The sensorless brushless motor has been started by performing a predetermined start-up excitation switching operation until the rotation speed of the motor rotor reaches a predetermined value. When the rotational speed of the rotor of the motor reaches a predetermined value, thereafter, the rotational position of the rotor is detected based on the voltage change at the neutral point of the armature coil group, and based on the detection result. The operation shifts to a normal operation in which the excitation of the armature coil is switched. [0005] However, such a conventional method of starting a motor has caused the following inconveniences. For example, when the motor is a three-phase sensorless brushless motor having three armature coil groups,
In the normal operation, the motor is driven by a so-called two-phase energizing pattern in which the motor is rotated by sequentially switching the six types of excitation patterns. At the same time, as the excitation switching operation at the time of starting, the motor is driven by the excitation switching operation of the two-phase conduction pattern. However, when the excitation switching operation is performed in the two-phase energizing pattern, the rotor of the motor becomes 60
Since the motor rotates by degrees, the output torque of the motor becomes uneven, and the motor cannot be started smoothly. At the same time, in an energizing pattern in which the output torque of the rotor is reduced, the rotor may rotate in the opposite direction. The present invention has been made in view of the above circumstances, and has as its object to provide a motor starting device capable of smoothly driving the rotor of a sensorless brushless motor at the time of starting. SUMMARY OF THE INVENTION The present invention relates to a motor starting device for starting a three-phase sensorless brushless motor having three sets of armature coils connected to a neutral point and not grounded in a Y-connection. A rotating magnetic field position detecting means for detecting a rotating position of the rotating magnetic field based on a neutral point voltage; a starting and ending determining means for determining whether to start the motor based on a detection signal of the rotating magnetic field position detecting means; A predetermined two-phase energization for energizing the armature coil for a predetermined time in a predetermined three-phase energization pattern in which a three-phase simultaneous energization and a two-phase simultaneous energization are mixedly energized for a predetermined time, and Excitation switching is performed in accordance with an excitation pattern, and motor drive control means is provided for shifting to a predetermined normal operation operation when the activation completion determination means determines the termination of activation in the excitation switching operation. Therefore, in the state immediately after the start of the startup, the excitation is switched for a predetermined time in a predetermined three-phase excitation pattern in which the three-phase simultaneous energization and the two-phase simultaneous energization are mixed and excited. Therefore, the change in the rotation angle of the rotor of the motor at the time of the excitation switching becomes smaller, whereby the rotation of the motor at the time of startup becomes smoother, the unevenness of the generated torque becomes smaller, and the rotor may rotate in the reverse direction. Can be avoided. Embodiments of the present invention will be described below in detail with reference to the accompanying drawings. FIG. 1 shows an electric bicycle according to one embodiment of the present invention. In FIG. 1, an electric bicycle 1 includes a frame 2, a front wheel 3, a rear wheel 4, a handle 5, a saddle 6, a pedal 7, and a transmission mechanism 8 for transmitting the power of the pedal 7 to the rear wheel 4. It is configured. A disk-shaped housing 10 provided on the hub 9 of the rear wheel 4 is provided with a motor 11 and a transmission mechanism (not shown) for transmitting the power of the motor 11 to the drive shaft of the rear wheel 7. Have been. This transmission mechanism includes a motor 11
A one-way clutch mechanism (for example, a ratchet) is provided for temporarily releasing the connection between the motor shaft and the rear wheel shaft when the rotation speed of the shaft of the rear wheel 7 does not match the rotation speed of the drive shaft of the rear wheel 7. Further, a sensorless brushless motor is used as the motor 11 because of its good maintainability and good ride comfort. In addition, a battery box 13 in which a battery for supplying electric power to the motor 11 is accommodated is provided on a loading platform 12 provided above the rear wheel 7. The right hand grip 14 of the handle 5 is provided with an accelerator device for the user to specify on / off and speed of the motor 11. For example, in the accelerator device, it is possible to operate a position for designating the motor 11 to be turned off, a position for designating a low speed, a position for designating a medium speed, and a position for designating a high speed. Are output to a motor control device described later. Also,
The steering wheel 5 includes a brake 15 for stopping the vehicle body,
16 are provided. FIG. 2 shows an example of a motor control device for controlling the drive of the motor 11. In this case,
The motor 11 is a sensorless brushless motor. In FIG. 1, a motor 11 has armature coils 11u, 11v, and 11w connected to a neutral point and non-grounded Y.
And a rotor 11r for generating a rotating magnetic field. The driving power of the battery 20 is applied to the armature coils 11u, 11v, 11w via the switching device 21. The switching device 21 is connected between the positive and negative poles of the battery 20 in series.
And three switching elements connected in parallel. The interconnection point between the switching element S1 and the switching element S2 connected in series is connected to the armature coil 11
u is connected to the other end of the switching element S3 and the switching element S4 are connected in series. The interconnection end of the switching element S4 is connected to the other end of the armature coil 11v. The interconnection end of S6 is connected to the other end of the armature coil 11w. Here, switching elements S1, S2, S3, S
Reference numerals 4, S5, and S6 each include an FET and a protection diode. The interconnection point of the armature coils 11u, 11v, and 11w, that is, the voltage Vn at the neutral point 11n is supplied to the plus input terminal of the comparator 22, the plus input terminal of the comparator 23, and the comparator 24. Are added to the negative input terminals. The voltage dividing resistors R1 and R2 divide the voltage E of the battery 20 by half, and the voltage (E / 2) at the voltage dividing point is applied to the negative input terminal of the comparator 22. Have been. The voltage dividing resistors R3, R4 and R5 are connected to the battery 20.
Is divided into 1/3 and 2/3.
The voltage (2E / 3) at the 2/3 voltage dividing point is calculated by the comparator 23
, And the voltage (E / 3) at the voltage dividing point of 1/3 is applied to the plus input terminal of the comparator 24. The comparator 22 determines that the voltage Vn is equal to the voltage (E / 2)
If the voltage Vn is larger than the voltage (E /
3) In the following cases, a comparison signal SC1 of a logic L level is output, and the comparison signal SC1 is applied to the gate circuit 25. The comparator 23 determines that the voltage Vn is equal to the voltage (2E /
If it is larger than 3), a comparison signal SC2 of a logic H level is output and the voltage Vn is
E / 3) In the following case, the comparison signal SC at the logical L level
2, and the comparison signal SC2 is applied to one input terminal of the OR circuit 26. The comparator 24 determines that the voltage Vn is equal to the voltage (E / 3)
If the voltage Vn is smaller than the voltage (E / E), a comparison signal SC3 of a logic H level is output.
3) In the above case, a comparison signal SC3 of a logic L level is output, and the comparison signal SC3 is applied to one input terminal of the OR circuit 26. The output of the OR circuit 26 is a gate control signal S
C4 is applied to the control signal input terminal of the gate circuit 25. The gate circuit 25 has a gate control signal SC4
Is at the logic L level, the input comparison signal SC1 is passed as it is and output as a signal SC5. On the other hand, when the gate control signal SC4 rises to the logic H level, the signal SC5 is output at the time of the rise. The signal SC5 is applied to the motor drive control unit 27 and the start / end determination unit 28. The start / end determination section 28 receives the input signal SC
5 periodically changes between the logical H level and the logical L level, and if the period during which the logical level is at the logical H level is the same as the period during which the logical level is at the logical L level, the motor 11 It is determined that the rotation speed of the rotor 11r has reached a sufficient value and the startup has been completed, and a startup completion determination signal DS representing the determination result is applied to the motor drive control unit 27. The motor drive control unit 27 includes switching elements S1, S2, S3, S4, S
5 and S6, control signals SS1, SS2, SS3, respectively.
The switching elements S1, S2, S3, S4, S5, and S6 are switched on and off by outputting SS4, SS5, and SS6.
The excitation states of 1u, 11v, and 11w are switched. Here, the motor drive control unit 27 controls the armature coils 11u, 11v, 11
w is excited to the initial setting state for a predetermined period of time. Thereafter, a predetermined start-up excitation switching operation is performed until the start-up end determination signal DS is output from the start-up end determination unit 28. In response to the change in the logic level of the signal SC5, the armature coil 1 of the motor 11
The normal operation is performed to excite 1u, 11v, and 11w in a predetermined excitation pattern (two-phase energization excitation pattern). In the normal operation, the motor drive control unit 27 controls the control signals SS1, SS2, SS3, SS4, SS4 in accordance with the position signal SP output from the accelerator device.
5, the level of SS6 is set.
The magnitude of the drive current applied to the armature coils 11u, 11v, 11w is set. Then, in the normal operation process, the motor drive control unit 27 performs the following operations as shown in FIGS.
Control signals SS1, SS2, SS3, SS4, SS5, S
Set the level of S6 to the pattern PT1, PT2, PT3, PT
4, PT5, and PT6 are sequentially switched (two-phase energization excitation pattern). Here, the control signals SS1, SS2, SS
3, SS4, SS5, and SS6 have low levels equal to the level "0" and the control signals SS1, SS2, and SS6.
When the magnitude of the drive current is controlled by the level control of the control signals SS1 to SS6, the high level of 3, SS4, SS5, SS6 is a voltage value corresponding to the position signal SP at that time. As described above, the control signals SS1, SS2, S
S3, SS4, SS5, SS6 are converted to patterns PT1, P
By sequentially switching to T2, PT3, PT4, PT5, and PT6, the rotor 11r of the motor 11 rotates in a predetermined direction at a predetermined speed. When switching to the patterns PT1 to PT6, the respective armature coils 11u, 11v, 11w
Are the terminal voltages Vu, Vv, Vw of FIG.
(I), the voltage Vn at the neutral point 11n of the armature coils 11u, 11v, 11w
Changes as shown in FIG. Here, the terminal voltages Vu, Vv, Vw include the switching elements S1 to S6.
SK on the pulse generated when switching on / off
, The voltage Vn also includes this noise component SKa. Therefore, the comparison signals SC1, SC2, SC3 output from the comparators 22, 23, 24 in accordance with the level change of the voltage Vn are shown in FIG.
(L), as shown in (m), whereby
The gate control signal SC4 output from the OR circuit 26 is
It changes as shown in FIG. That is, the gate control signal SC4 changes from the logic L level to the logic H at the timing immediately before the signal component of the noise component SKa of the voltage Vn is output to the comparison signal SC1.
At the same time as the level rises, the motor drive control unit 27 changes to a mode of falling to the logic L level at a timing immediately before an edge necessary for the timing of the excitation switching operation appears. As a result, the signal SC5 output from the gate circuit 25 becomes the comparison signal S as shown in FIG.
The signal of the noise component SKa included in the voltage Vn is removed from C1. The motor drive control unit 27 outputs the signal SC5
Is a predetermined electrical angle (for example, 30 degrees) corresponding to the excitation switching cycle at that time, with a rising edge rising from a logic L level to a logic H level and a falling edge falling from a logic H level to a logic L level. In a state in which the patterns PT1 to P6 of the control signals SS1 to SS6 are delayed.
The switching operation of T6 is performed. In this manner, when the motor 11 is operating normally, the rotor 11r has a sufficient rotation speed, so that the voltage Vn at the neutral point 11r of the armature coils 11u, 11v, 11w is appropriately adjusted. And the signal SC5 periodically changes to a logic H level and a logic L level, and
The period T1 of the logic H level and the period T2 of the logic L level have substantially the same value. That is, by detecting the level change of the signal SC5, it can be determined whether or not the motor 11 is in a state where the normal operation process can be applied.
This is employed as a determination condition for the start / end determination unit 28 to determine the start / end, as described above. On the other hand, in the start-up processing, the motor drive control unit 27, immediately after the start-up, controls the control signals SS1, SS2, SS3, SS3 as shown in FIGS.
4, SS5, SS6, the levels of the patterns PT1a, P1
T1b, PT2a, PT2b, PT3a, PT3b, P
T4a, PT4b, PT5a, PT5b, PT6a, P
The motor 11 is driven by a three-phase energizing excitation pattern that is sequentially switched to 12 types of T6b. As described above, the control signals SS1, SS2, S
S3, SS4, SS5, and SS6 are converted to patterns PT1a,
PT1b, PT2a, PT2b, PT3a, PT3b,
PT4a, PT4b, PT5a, PT5b, PT6a,
By sequentially switching to the PT 6b, the rotor 11r of the motor 11 rotates in a predetermined direction at a predetermined speed. At the same time, each time the excitation is switched, the rotational position is switched by 30 °. When the motor 11 is driven in the three-phase energized excitation switching pattern in this manner, the angle of rotation of the rotor 11r every time the excitation is switched becomes 1/2 of that in the normal operation shown in FIG. Rotation becomes smooth. FIG. 5 shows a processing example of the motor drive control section 27. The motor drive control unit 27 monitors that the position signal SP has changed (NO loop of the judgment 101), and the position signal SP changes and the result of the judgment 101 is Y
When it becomes ES, it is checked whether or not the position signal SP is of the operation position of "motor off" (decision 102). If the result of determination 102 is YES, a flag Foff for storing the state where the motor 11 is off is set (process 103), and the control signal SS
1 to SS6 are stopped, the excitation switching operation of the motor 11 is stopped, the motor 11 is stopped (process 104), and the process returns to the judgment 101. The position signal SP changes, and the value after the change is that of an operation position other than “motor off”.
When the result of 02 is NO, it is checked whether or not the flag Foff is set (decision 105). If the result of determination 105 is YES, the motor has been switched from the "motor off" state to an operation position for designating one of the speeds. Therefore, at this time, the motor 11 is started. That is, first, the flag Foff is cleared (step 106), and a predetermined three-phase energization start process is started (step 107).
It is executed and waits until the rotation speed of the rotor 11r of the motor 11 increases to some extent (NO loop of the judgment 108).
Here, the three-phase energization start processing refers to the control signals SS1 to SS
6 is set in a pattern of a predetermined initial setting state, the initial setting state is maintained for a predetermined time, and the level of the control signals SS1 to SS6 is changed at a predetermined switching cycle at the time of the pattern PT.
1a, PT1b, PT2a, PT2b, PT3a, PT
3b, PT4a, PT4b, PT5a, PT5b, PT
This is an operation of driving with a three-phase energization excitation pattern of 6a and PT6b. As described above, when the rotation speed of the rotor 11r of the motor 11 increases to some extent in the three-phase energization start processing, and the result of the judgment 108 becomes YES, the motor drive control unit 2
7 starts a predetermined two-phase energization activation process (process 10).
9). Here, the two-phase energization start processing is defined as the control signal SS1
~ SS6 level by pattern PT1, PT2, PT
This is an operation of driving with the two-phase energizing excitation pattern of 3, PT4, PT5, and PT6. Thus, the armature coils 11u, 11
The voltage V as described above is applied to the neutral point 11n
Since n occurs, the activation end determination unit 28 can perform the activation end determination operation described above. Therefore, the motor drive control unit 27 waits until the startup completion determination signal DS is output from the startup completion determination unit 28 (NO loop of the determination 110). After the start of the motor 11 is completed, a decision 118 is made.
When the result is YES, the levels of the control signals SS1 to SS6 are switched to the patterns PT1 to PT6 (two-phase energization pattern) with reference to the signal SC5, and the value of the drive current is changed by operating the position signal SP at that time. The normal operation process for controlling the size corresponding to the position is started (process 1).
11) The motor 11 is operated normally, and the process returns to the judgment 101. When the motor speed is changed in the normal operation state and the result of determination 105 is NO, the value of the drive current of the motor 11 is set to correspond to the operation position of the position signal SP at that time. Control to a value (process 11
2) Return to decision 101. As described above, in this embodiment, immediately after the start, the excitation switching pattern of the motor 11 is changed to 12 types of 3
Since the phase energization excitation pattern is set, the rotation angle of the rotor 11r is set to 1 in normal operation every time the excitation is switched.
/ 2, the movement of the rotating magnetic field becomes smooth, so that the unevenness of the torque generated by the motor 11 is reduced, and problems such as the reverse rotation of the rotor 11r are prevented from occurring, and a stable start-up operation is performed. Can be. In the embodiment described above, immediately after the motor 11 is started, the motor 11 is driven in the three-phase excitation energizing pattern so that the rotation of the motor 11 becomes smooth.
Motor 1 with well-known three-phase AC inverter
When 1 is driven, the rotation of the rotor 11r becomes continuous,
The rotation of the motor 11 becomes smoother. FIGS. 6A to 6F show an example of the three-phase AC inverter energizing excitation pattern. Other than the above, the three-phase AC inverter energization excitation pattern includes, for example, an energization excitation pattern by a triangular wave comparison PWM method that can make the rotation of the motor 11 smoother. In the above-described embodiment, the present invention is applied to the activation of the sensorless brushless motor mounted on the electric bicycle. However, when the sensorless brushless motor mounted on other devices is activated, the present invention is also applicable.
The present invention can be similarly applied. As described above, according to the present invention,
Immediately after the start of the start, the excitation is switched for a predetermined time in a predetermined three-phase excitation pattern in which the three-phase simultaneous energization and the two-phase simultaneous energization are mixed and excited. The change in the rotation angle becomes smaller, whereby the rotation of the motor at the time of startup becomes smoother, the unevenness of the generated torque becomes smaller, and the effect that the rotor reverses can be avoided. [0059]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic perspective view showing an electric bicycle according to one embodiment of the present invention. FIG. 2 is a block diagram showing a motor control device according to one embodiment of the present invention. FIG. 3 is an operation waveform diagram for explaining an operation during a normal operation. FIG. 4 is an operation waveform diagram showing an example of a three-phase energization excitation pattern. FIG. 5 is a flowchart illustrating an example of processing of a motor drive control unit. FIG. 6 is an operation waveform diagram showing an example of a three-phase AC inverter energization excitation pattern. [Description of Signs] 11 Motors 11u, 11v, 11w Armature coil 11r Rotor 20 Battery 21 Switching device 22, 23, 24 Comparator 25 Gate circuit 26 OR circuit 27 Motor drive control unit 28 Startup / end determination unit

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-4-101696 (JP, A) JP-A-5-310176 (JP, A) JP-A-6-70587 (JP, A) JP-A-1- 283090 (JP, A) JP-A-62-230392 (JP, A) JP-A-61-52194 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H02P 6/20 B62M 23 / 02 H02P 6/16

Claims (1)

(57) [Claim 1] A motor starting device for starting a three-phase sensorless brushless motor having three sets of armature coils connected to a neutral point non-grounded Y-connection, wherein: A rotating magnetic field position detecting means for detecting a rotating position of the rotating magnetic field based on the neutral point voltage; a starting and ending determining means for determining whether to start the motor based on a detection signal of the rotating magnetic field position detecting means; Armature coil, 3 phase simultaneous energization and 2 phase simultaneous
After a predetermined time excited switching in a predetermined three-phase power excitation pattern power excitation mixed energization and, to the power excitation 2-phase simultaneously
That excited switching at a predetermined two-phase power excitation pattern, when in its energized changeover operation is the start completion determining means determines the completion boot, and further comprising a motor drive control means shifts to a predetermined normal running operation Motor starter.