JP2008236892A - Controller for brushless motor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To inexpensively achieve the suppression and control of electricity generated through simple circuitry with a no-load number of revolutions or higher. <P>SOLUTION: When it is determined at a regenerative duty determination circuit 42 that the duty ratio is zero, advance angle is fixed at a predetermined value by an advance offset setting circuit 39 to increase/decrease the driving duty ratio. When it is determined by an output duty determining circuit 36 that the driving duty ratio is a maximum, the advance is increased/decreased by a predetermined advance or more to increase/decrease a regenerative current. The amount of advance is fixed within a range between a no-load number of revolutions and a predetermined number of revolutions. Since the duty ratio is increased/decreased, however, power generation control can be carried out at the same level as cases where the advance is controlled within a range from 0 to a predetermined advance value. Furthermore, when the predetermined number of revolutions is exceeded and the electricity generated is increased, the advance increase/decrease control can be carried out with the maximum duty ratio within that range of revolving speed to control the electricity generated. Since this circuit for this setting of a fixed advance value or increasing/decreasing of the driving duty ratio can be constructed, without making special enhancement in accuracy, the price of the circuity will not increase. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a control device for a brushless motor that performs advance angle control.

Conventionally, there has been one that uses a DC brushless motor as a drive source for an electric vehicle, and motor regenerative control is performed in order to perform braking similar to engine braking in an internal combustion engine vehicle during long downhill running (See, for example, Patent Document 1).
JP 2002-58277 A

  However, when driving on a long downhill with the drive control stopped, the speed is naturally increased and the rotational speed may increase beyond the no-load rotational speed of the motor. The regenerative current flowing from the device (controller) to the power source (battery) cannot be controlled. For this reason, for example, when the power source is a battery, overcharge occurs, or the motor friction increases according to the increase in regenerative energy. In that case, for example, in a case where a bridge circuit is configured as a current supply circuit, the output of the bridge is switched from boost operation to 100% duty drive (maximum duty drive control), and at a rotational speed higher than the no-load rotational speed. The amount of power generation can be suppressed by increasing or decreasing the advance amount in accordance with the increase or decrease.

  However, in the above control, the advance angle control is performed in the driving state with 100% duty, and even if a slight error occurs in the advance angle control, the drive amount is determined with a magnitude corresponding to the 100% duty. It would react excessively to the error, and it was easy to cause hunting that repeats driving and regeneration. Therefore, it is necessary to increase the control accuracy, and there is a problem that the cost of the control device increases.

  In order to solve such a problem and realize low-cost control of power generation with a simple circuit configuration at a rotational speed higher than the no-load speed, in the present invention, the stator is coaxial with the stator and rotates. A brushless motor in which a coil winding is provided on one of the possible rotor, the stator and the rotor, and a permanent magnet is disposed opposite the coil winding on the other of the stator and the rotor. A rotation detection means for detecting a rotation state of the rotor relative to the stator, a drive current supply means for supplying a drive current to the coil winding, and a current detection means for detecting the drive current; Pulse width modulation for supplying to the drive current supply means a control signal that is in phase with the rotation angle detection signal of the rotor detected by the rotation detection means and is pulse width modulated. Signal generating means, output duty determining means for supplying a duty signal for determining a duty ratio of the control signal to be pulse width modulated to the pulse width modulated signal generating means, and the pulse width modulation by the pulse width modulated signal generating means Control means for advancing the phase of the control signal generated, and the control means has an excessive regenerative current even when the rotor reaches a no-load rotational speed and the regenerative duty is zero. A fixed advance value setting means for fixing the advance angle by the advance angle control means to a value obtained by advancing a predetermined amount when it is determined that the advance angle control means is in a state where the rotation speed of the rotor is not In a range that reaches a predetermined rotational speed that is equal to or higher than the load rotational speed, the predetermined amount is advanced and a fixed advance value is set, and at the predetermined rotational speed or higher, the advance angle is increased or decreased according to the increase or decrease of the rotational speed. The output duty determining means increases / decreases the duty ratio according to increase / decrease of the rotational speed in a range reaching the predetermined rotational speed equal to or higher than the no-load rotational speed, and fixes the duty ratio to a predetermined maximum duty ratio above the predetermined rotational speed. It was supposed to be.

  As described above, according to the present invention, for example, in a brushless motor used in an electric vehicle, when the motor reaches a no-load rotational speed when traveling on a downhill and the regenerative current becomes excessive even when the regenerative duty is zero. Is a value obtained by advancing the advance angle by a predetermined amount in a range up to a predetermined rotation speed equal to or higher than the no-load rotation speed, and is fixed to that value, and in that range, the duty ratio increases or decreases according to the increase or decrease of the rotation speed. Since the control is performed, the duty ratio is increased / decreased according to the increase / decrease of the rotation speed without switching to the 100% duty control as soon as the no-load rotation speed is exceeded. Is called. In this case, the advance amount is fixed in the range between the no-load rotation speed and the predetermined rotation speed. However, since the duty ratio is increased or decreased as described above, the advance angle control is performed in the range of 0 to the predetermined advance angle value. The power generation control can be performed in the same way as in the case of power generation, and when the rotational speed increases beyond the predetermined rotational speed and the power generation amount increases, the advance angle increase / decrease control based on the maximum duty ratio is performed in the rotational speed range. The amount can be controlled. Since the circuit for setting such a fixed advance value and increasing / decreasing the drive duty ratio can be configured without particularly increasing the accuracy, the circuit does not rise.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a block circuit diagram of a motor control device for a motor according to the present invention. Further, it is a motor control device for a motor M used as a drive source of an electric automobile. In the illustrated example, an outer rotor type motor is used, and wheels are attached to the outer rotor. In the illustrated example, the three-phase brushless motor M is shown, but this is an example, and the motor to be controlled is not limited.

  In the illustrated example, each phase coil 9 of the motor M is connected to an in-vehicle battery BT as a power source via an inverter 21 as a drive current supply means in which a bridge circuit using an FET is configured. The power supply line connecting the battery BT and the inverter 21 is provided with a current detection sensor 22 and a voltage detection sensor 23 as current detection means, and a current detection signal and a voltage detection signal detected by each of them are provided. These are inputted to the current detection circuit 25 and the voltage detection circuit 26 of the control circuit ECU constituting the control means. The motor M is provided with a rotation sensor 24 as a rotation detection means for detecting the rotation angle of the rotor 4. The rotation angle signal is input to the rotation angle detection circuit 27 and the rotation speed detection circuit 41 to detect the rotation angle. The circuit 27 calculates the rotational (angle) position of the rotor 4 with respect to the stator 6, and the rotational speed detection circuit 41 calculates the rotational speed of the rotor 4 with respect to the stator 6.

  Further, in the control circuit ECU, a driving operation input circuit 28 to which a driving operation signal which may be a signal from an external accelerator opening sensor (not shown), for example, is input, and an output from the driving operation input circuit 28 is provided. The output current command circuit 29 serving as an output command signal generating means and the regenerative current command circuit 30 serving as a regenerative current command means, and the output signals from the output current command circuit 29 and the current detection circuit 25 are input. Output current comparison circuit 31, regenerative current comparison circuit 32 to which each output signal from regenerative current command circuit 30 and current detection circuit 25 is input, regenerative current comparison circuit 32, voltage detection circuit 26, and rotation speed detection circuit 41. Can be accessed by a regenerative duty determining circuit 34 as a regenerative duty determining means to which each output signal is input and a regenerative duty determining circuit 34 A memory 35 storing various map data, a regenerative duty determination circuit 42 to which a regenerative duty determination signal from the regenerative duty determination circuit 34 is input, and a fixed advance angle to which an output signal from the regenerative duty determination circuit 42 is input. An advance angle offset setting circuit 39 as value setting means, and an output duty determination circuit 33 as output duty determination means to which output signals from the output current comparison circuit 31, regenerative current comparison circuit 32, and regeneration duty determination circuit 42 are input. An output duty determination circuit 36 to which an output signal from the output duty determination circuit 33 is input, an output duty determination circuit 36, a regenerative duty determination circuit 42, a regenerative current comparison circuit 32, an output current comparison circuit 31, and an advance angle offset setting. Each output signal from the circuit 39 is input, and an advance angle signal is output according to the input value. Each of the output signals from the advance angle control circuit 37 as the advance angle control means, the output duty determination circuit 33, the regenerative duty determination circuit 34, the rotation angle detection circuit 27, and the advance angle control circuit 37 are input and their input values. There is provided a PWM signal generation circuit 38 as pulse width modulation signal generation means for outputting a PWM signal generated according to the above to the inverter 21. Each circuit may include a circuit configured using an IC and a circuit configured by CPU program control. Further, detailed description of the parts understood by the illustrated circuit names and signal lines will be omitted.

  In the output duty determination circuit 33, the duty ratio in the drive (acceleration / deceleration) output control is determined based on the output determination value from the output current comparison circuit 31, and the duty ratio determination signal is output to the PWM signal generation circuit 38. The regeneration duty determination circuit 34 determines the duty ratio in the regeneration control based on the output determination value from the regeneration current comparison circuit 32 and outputs the duty ratio determination signal to the PWM signal generation circuit 38. Further, the advance angle control circuit 37 determines an advance value in the advance angle control based on each input value, and outputs the advance angle determination signal to the PWM signal generation circuit 38. The PWM signal generation circuit 38 determines a PWM signal as a control signal that is pulse-width-modulated in a known PWM control for a brushless motor and that corresponds to the duty ratio.

  In the regenerative control, the chopping control of the FET is performed in the case of the three-phase brushless motor of the illustrated example and the inverter 21 is configured by a three-phase full bridge circuit using the FET. At the chopping duty 0, all FETs are turned off, and the regenerative current is full-wave rectified via the parasitic diodes of the FETs.

  Next, the regenerative control procedure according to the present invention will be described with reference to the flowchart of FIG. 2 and the control diagram of FIG.

  In FIG. 3, the horizontal axis indicates the rotational speed of the motor (rotor 4), the vertical axis indicates the duty ratio Dy and the advance value in regeneration or drive duty control, and when the rotational speed is below the no-load rotational speed No. The state in which the duty angle control is performed and the advance angle control is performed when the no-load rotational speed No is exceeded is shown.

  In step ST1 of FIG. 2, the target regenerative current Io and the current regenerative current In are read. The target regenerative current Io is a regenerative current value determined by the regenerative current command circuit 30, and the current regenerative current In is a current value detected by the current detection sensor 22. In the next step ST2, it is determined whether or not the advance angle in the advance angle control is 0 degree. If it is determined that the advance angle is 0 degree (not being advanced angle control), the process proceeds to step ST3.

  In step ST3, it is determined whether or not the target regenerative current In is smaller than the current regenerative current Io. If it is determined that the target regenerative current Io is smaller, that is, it is determined that the regenerative current flows too much, the process proceeds to step ST4. If it is determined that the target regenerative current Io is larger, that is, the regenerative current is small, step ST5. Proceed to In step ST4, it is determined whether or not the regenerative duty ratio (Dy) is minimum (= 0). If it is determined to be minimum, the process proceeds to step ST6. In this step ST3 and 4, it can be determined that the regenerative current is excessive even if the rotor reaches the no-load rotational speed and the regenerative duty is set to 0. In this case, in step ST6, the advance by the advance angle control circuit 37 is determined. The angle control amount is set to an advance angle D1 (for example, 10 degrees) as a predetermined fixed advance value by the advance angle offset setting circuit 39, and the process returns to step ST1.

  When the process proceeds from step ST3 to step ST5, the area is equal to or less than the no-load rotational speed No, and the current regenerative current In is smaller than the target regenerative current Io in the increase / decrease control of the regenerative duty ratio (Dy). . Therefore, control for increasing the regenerative duty ratio (Dy) is performed in step ST5, and the process returns to step ST1.

  If it is determined in step ST4 that the regenerative duty ratio (Dy) is not the minimum, the process proceeds to step ST7. In this case, since it is an area of increase / decrease control of the regenerative duty ratio (Dy) (no load rotation speed No or less), in step ST7, control is performed to reduce the regenerative duty ratio (Dy), and the process returns to step ST1.

  If it is determined in step ST2 that the advance angle is not 0 degrees, the process proceeds to step ST8. In this case, the advance angle control is being performed, and the control is performed in a region exceeding the no-load rotational speed No in FIG. In step ST8, it is determined whether or not the target regenerative current Io is smaller than the current regenerative current In. If the target regenerative current Io is smaller, that is, if it is determined that the regenerative current is excessive, the process proceeds to step ST9. When it is determined that the regenerative current Io is larger, that is, the regenerative current is small, the process proceeds to step ST10.

  In step ST9, the output duty determination circuit 36 determines whether or not the drive duty ratio (Dy) is maximum (for example, 100%). If it is determined to be maximum, the process proceeds to step ST11 and is not maximum. When it is determined that, step ST12 follows. In step ST11, the drive duty ratio (Dy) is maximized, and the region is equal to or higher than the rotational speed N1 in FIG. 3, and the advance angle is set according to the drive duty ratio maximum determination signal from the output duty determination circuit 36. The control circuit 37 performs control to increase the advance amount so as to reduce the regenerative current (two-dot chain line in the figure). Note that the rotational speed N1 in FIG. 3 is shown as a guideline, and does not set a specific rotational speed, but is a value that is appropriately determined according to each value of the advance angle, the regenerative current, and the duty ratio Dy. Further, when the process proceeds to step ST12, the drive duty ratio (Dy) is not maximized, that is, between the no-load rotation speed No and the rotation speed N1 in FIG. Since the ratio (Dy) can be increased, control is performed to increase the drive duty ratio (Dy) in order to reduce the regenerative current, and the process returns to step ST1.

  In step ST10, it is determined whether or not the advance angle is larger than a predetermined advance angle D1. If it is determined that the advance angle is equal to or less than the predetermined advance angle D1 (= D1), the process proceeds to step ST13. In step ST13, the drive duty ratio (Dy) is controlled to increase the regenerative current, and the process proceeds to step ST14. move on. In step ST14, it is determined whether or not the drive duty ratio (Dy) is 0%. When it is determined that the drive duty ratio (Dy) is 0%, the process proceeds to step ST15, where the advance angle is set to 0 degree and the process returns to step ST1. In this case, it corresponds to the no-load rotational speed No in FIG. 3, and when the advance angle is set to 0 degree, and the rotational speed decreases from there, the regenerative duty ratio (Dy) at the advance angle of 0 degree. The control can be promptly shifted to the control by the increase / decrease. When it is determined in step ST14 that the drive duty ratio (Dy) is not 0%, the process returns to step ST1.

  If it is determined in step ST10 that the advance angle is larger than the predetermined advance angle D1 (on the higher rotation side than the rotation speed N1 in FIG. 3), the process proceeds to step ST16, in which case the drive duty ratio (Dy) In step ST16, control is performed to reduce the advance angle in order to increase the regenerative current, and the process returns to step ST1.

  As described above, the increase / decrease in the regenerative current can be adjusted by increasing / decreasing the regeneration duty ratio from 0 rpm to no-load rotation speed No. When the regenerative duty ratio corresponding to the no-load rotation speed No becomes 0, the advance angle is set to the predetermined advance angle D1, and in the region reaching the predetermined rotation speed N1 greater than the no-load rotation speed No. It is set to a constant value by a predetermined advance angle D1. In the No to N1 region where the advance angle D1 is constant, the regeneration current increase / decrease control cannot be performed by the advance angle, but the regeneration current increase / decrease control can be performed by increasing / decreasing the drive duty ratio. In addition, since the drive duty ratio is maximum in a region where the rotational speed is N1 or more, the regenerative current increase / decrease control cannot be performed by increasing / decreasing the duty ratio, but the regenerative current increase / decrease can be increased / decreased. Control can be performed.

  By controlling in this way, when switching from boost regeneration to regenerative control by advance drive, the duty ratio is increased or decreased with the advance angle kept constant, so the drive duty ratio is set at no-load rotation speed as in the prior art. It is possible to prevent the occurrence of hunting that repeats driving and regeneration before and after the no-load rotation speed in the maximum one, and the circuit for setting the fixed advance value D1 and increasing / decreasing the driving duty ratio is particularly high. Since the control circuit can be configured without increasing the accuracy, the circuit does not increase. Further, the present invention is not limited to the case where the boost regeneration is switched to the advance angle control, but is also effective in the case where the state is not energized (running state) or the drive state is switched to the advance angle drive.

  The control device of the brushless motor according to the present invention enables regenerative control even when exceeding the no-load rotational speed, and can perform smooth regenerative control without causing hunting in the regenerative control near the no-load rotational speed. This is useful as drive control for electric vehicles.

It is a block circuit diagram of a motor control device of a motor based on the present invention. It is a control flowchart based on this invention. It is a control diagram which shows the control point based on this invention.

Explanation of symbols

4 Rotor 6 Stator 9 Coil 21 Inverter 22 Current detection sensor 25 Current detection circuit 32 Regeneration current comparison circuit 34 Regeneration duty determination circuit 36 Output duty determination circuit 37 Advance angle control circuit 38 PWM signal generation circuit 39 Advance angle offset setting circuit 42 Regeneration duty Judgment circuit ECU Control circuit M Motor

Claims (1)

A stator, a rotor provided coaxially and rotatably with respect to the stator, a coil winding is provided on one of the stator and the rotor, and the other of the stator and the rotor is opposed to the coil winding. A control device for a brushless motor in which permanent magnets are arranged,
Rotation detection means for detecting a rotation state of the rotor with respect to the stator; drive current supply means for supplying a drive current to the coil winding; and current detection means for detecting the drive current;
A pulse width modulation signal generating means for supplying a control signal, which is in phase with the rotation angle detection signal of the rotor detected by the rotation detection means and is pulse width modulated, to the drive current supply means; and the pulse width modulation An output duty determining means for supplying a duty signal for determining a duty ratio of the control signal to be supplied to the pulse width modulation signal generating means, and a phase of the pulse width modulated control signal by the pulse width modulation signal generating means is advanced. Control means comprising an advance angle control means for causing
The control means fixes the advance angle by the advance angle control means to a value advanced by a predetermined amount when it is determined that the regenerative current is excessive even when the rotor reaches the no-load rotation speed and the regenerative duty is zero. Fixed advance value setting means,
The advance angle control means advances the predetermined amount within a range where the rotation speed of the rotor reaches a predetermined rotation speed that is equal to or higher than the no-load rotation speed and sets a fixed advance value, and is equal to or higher than the predetermined rotation speed. Now, increase or decrease the advance angle according to the increase or decrease of the rotation speed,
The output duty determining means increases or decreases the duty ratio according to an increase or decrease of the rotational speed in a range reaching a predetermined rotational speed equal to or higher than the no-load rotational speed and is fixed to a predetermined maximum duty ratio above the predetermined rotational speed. A control device for a brushless motor.

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