JP2017184427A - Drive circuit and starting method of motor, printer device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress or reduce noise at startup.SOLUTION: A feedback controller 102 adjusts a control command value Vby feedback control so that the detection value of the number of revolution of a motor 202 approaches a target value. When controlling the motor 202 in open loop, an open loop controller 104 generates a constant startup command value Vcapable of stabilizing the number of revolution of the motor 202 to a target value ωin steady state. A drive voltage controller 112 (ii) applies a drive voltage Vm according to control command value Vto the motor 202 in a first mode, and (ii) applies a drive voltage Vm according to the startup command value Vto the motor 202 in a second mode.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a brushless motor control technique.

  Brushless motors are used in various applications. FIG. 1 is a control block diagram of a drive system of a brushless motor (simply called a motor). The drive system 600 includes a motor 602 and a drive circuit 604 that drives the motor 602.

The drive circuit 604 includes a speed detector 606, an error detector 608, a speed controller 610, and a drive voltage controller 612. The speed detector 606 generates a detection value ω _FB for the number of rotations of the motor 602. The error detector 608 generates an error signal δω based on an error (deviation) between the rotation speed detection value ω _FB and its target value ω _REF . The speed controller 610 generates a command value V _CTRL corresponding to the error signal δω. The drive voltage controller 612 applies a drive voltage Vm corresponding to the command value V _CTRL to the motor 602. In the control system 600, the drive voltage Vm is feedback-controlled so that the rotation speed detection value ω _FB approaches the target value ω _REF, and the influence of disturbance is removed.

JP 2001-186790 A

As a result of examining the activation sequence of the control system 600 in FIG. 1, the present inventor has come to recognize the following problems. FIG. 2 is an operation waveform diagram when the motor 602 is started from the stop state ω = 0 toward the target rotational speed ω _REF in the control system 600 of FIG. 1. The rotational speed ω gradually converges toward the target value ω _REF .

The coil current Im that contributes to the motor torque is given by the following equation.
Im = (Vm−K _e ω) / (sL + Ra)
L is the inductance of the coil, and Ra is the internal resistance of the motor. K _e ω represents a counter electromotive force and is proportional to the rotational speed ω.

In the acceleration process shown in FIG. 2, since the rotational speed ω increases from zero toward the target value ω _REF , the term K _e ω changes greatly immediately after the start of the motor and thereafter. That is, the stable loop gain changes according to the rotational speed ω. On the other hand, in the control system 600 of FIG. 1, the loop gain is constant, and as a result, the drive voltage Vm oscillates as shown in FIG. When vibration of the drive voltage Vm occurs at an audible frequency, noise (acoustic noise) is generated.

  The present invention has been made in view of such a problem, and one of the exemplary purposes of an aspect thereof is to provide a motor drive circuit capable of suppressing or reducing noise at the time of startup.

  One embodiment of the present invention relates to a motor drive circuit that drives a motor. The motor drive circuit includes a feedback controller that adjusts the control command value by feedback control so that the detected value of the motor speed approaches the target value, and the motor speed in a steady state when the motor is controlled in an open loop. An open loop controller that generates a constant start command value that can be stabilized at a target value; and (ii) a drive voltage corresponding to the control command value is applied to the motor in the first mode, and (ii) a start command in the second mode. A drive voltage controller that applies a drive voltage corresponding to the value to the motor. The drive voltage controller is set to the second mode when starting the motor from the stopped state of the motor.

  During the second mode, the drive voltage is maintained at a substantially constant value according to the start command. Therefore, vibration due to feedback does not occur in the drive voltage, so that noise during startup can be suppressed or reduced.

The open loop controller has a response waveform of the motor speed ω,
ω = Vm / Kt × {1-e ^{(−t / τ)} }
When represented by
Vm = Kt × ω _REF
The start command value may be generated so that the drive voltage Vm that satisfies the above is obtained. Kt is a parameter specific to the motor.
The motor is represented as a first-order lag system, and when the drive voltage is kept constant, the rotation speed of the motor increases according to the step response of the first-order lag system. According to this aspect, the rotational speed ω can be gradually increased toward the target value ω _REF .

  The drive voltage controller may be set to the second mode when the target value of the rotation speed of the motor is changed from the first value to the second value. Noise can be reduced or suppressed not only when starting from a stop but also when changing the rotational speed.

  The drive voltage controller may be set to the first mode after a predetermined time has elapsed after starting the motor. The drive voltage controller may be set to the first mode when the error between the detected value of the rotational speed and the target value becomes smaller than the allowable value after starting the motor.

  The motor may be a three-phase motor. The drive voltage controller can switch between the 120-degree energization method and the 180-degree energization method, and is set to the second mode in the first period after the start of the motor, drives the motor with the 120-degree energization method, and then continues to the second The second mode is set in the second period and the motor is driven by the 180-degree energization method, and the third period following the second period is set in the first mode and the motor is driven by the 180-degree energization method and the open loop controller. During the first period, when the motor is controlled in an open loop, the start command value is set to a value that can stabilize the rotation speed of the motor at a sub target value lower than the target value in a steady state. During this period, the start command value may be set to a value that can stabilize the motor speed at the target value in a steady state when the motor is controlled in an open loop. .

  The first period may be a period from the start of activation until a predetermined time elapses. The first period may be a period from the start of activation until the rotation speed detection value reaches a predetermined value.

  The feedback controller may include an error detector that generates an error signal corresponding to an error between the detected value of the rotation speed and the target value, and a speed controller that generates a control command value corresponding to the error signal.

  The drive voltage controller may drive the motor with PWM (Pulse Width Modulation), and the control command value and the start command value may be a duty command value of PWM drive.

  The error detector receives an internal clock signal having a frequency corresponding to the number of rotations of the motor and an input clock having a frequency corresponding to the target value, and as an error signal, an acceleration signal and a deceleration signal corresponding to the error of those frequencies A speed discriminator may be included. The speed controller may include an integrating amplifier that integrates the acceleration and deceleration signals.

  The motor may be FG magnetized. An internal clock may be generated by multiplying the frequency of the FG signal obtained from the motor.

  The drive voltage controller includes a pulse width modulator that generates a pulse width modulation signal having a duty ratio according to a control command value or a start command value, and an inverter that applies a drive voltage to the motor according to the pulse width modulation signal. May be included.

The drive circuit may be integrated on a single semiconductor substrate.
“Integrated integration” includes the case where all of the circuit components are formed on a semiconductor substrate and the case where the main components of the circuit are integrated. A resistor, a capacitor, or the like may be provided outside the semiconductor substrate.
By integrating the circuit on one chip, the circuit area can be reduced and the characteristics of the circuit elements can be kept uniform.

  Another aspect of the present invention relates to a printer apparatus. The printer device includes a three-phase motor, one of the motor drive circuits described above that drives the three-phase motor, and a paper feed mechanism to which the three-phase motor is attached.

  Note that any combination of the above-described constituent elements and the constituent elements and expressions of the present invention replaced with each other among methods, apparatuses, systems, and the like are also effective as an aspect of the present invention.

  According to an aspect of the present invention, noise at startup can be suppressed or reduced.

It is a control block diagram of the drive system of a three-phase brushless motor. FIG. 2 is an operation waveform diagram when the motor is started from a stopped state ω = 0 toward a target rotational speed ωREF in the control system of FIG. 1. It is a block diagram of a control system provided with the drive circuit concerning an embodiment. FIG. 4 is an operation waveform diagram of the drive circuit of FIG. 3. FIG. 4 is another operation waveform diagram of the drive circuit of FIG. 3. It is a circuit diagram of a control system provided with the drive circuit which drives a three-phase motor. It is a wave form diagram which shows a 120 degree | times electricity supply system. FIG. 4 is a circuit diagram of a drive circuit that drives a motor by switching between a 120-degree energization method and a 180-degree energization method. It is a wave form diagram which shows a 180 degree | times energization system. It is a perspective view of a printer apparatus provided with the drive circuit of FIG. 6 or FIG.

  The present invention will be described below based on preferred embodiments with reference to the drawings. The same or equivalent components, members, and processes shown in the drawings are denoted by the same reference numerals, and repeated descriptions are omitted as appropriate. The embodiments do not limit the invention but are exemplifications, and all features and combinations thereof described in the embodiments are not necessarily essential to the invention.

In this specification, “the state in which the member A is connected to the member B” means that the member A and the member B are electrically connected in addition to the case where the member A and the member B are physically directly connected. It includes the case of being indirectly connected through another member that does not affect the connection state.
Similarly, “the state in which the member C is provided between the member A and the member B” refers to the case where the member A and the member C or the member B and the member C are directly connected, as well as an electrical condition. It includes the case of being indirectly connected through another member that does not affect the connection state.

  FIG. 3 is a block diagram of a control system 200 including the drive circuit 100 according to the embodiment. The control system 200 includes a motor 202 and a drive circuit 100.

The drive circuit 100 receives the target value ω _REF of the rotational speed of the motor 202 and stabilizes the rotational speed of the motor 202 to the target value ω _REF . The drive circuit 100 may be a functional IC (Integrated Circuit) integrated on a single semiconductor substrate. The drive circuit 100 includes a feedback controller 102, an open loop controller 104, and a drive voltage controller 112.

The feedback controller 102 adjusts the control command value V _CTRL by feedback control so that the detected value ω _FB of the rotational speed ω of the motor 202 approaches the target value ω _REF . For example, the feedback controller 102 includes a speed detector 106, an error detector 108, and a speed controller 110. The speed detector 106 monitors the number of rotations of the motor 202 and generates a detection value ω _FB thereof.

The speed detector 106 may monitor an FG signal from an FG magnetized motor, may monitor a Hall signal from a Hall element, or may monitor a signal from a rotary encoder. Part or all of the speed detector 106 may be provided outside the IC of the drive circuit 100. The error detector 108 generates an error signal δω corresponding to the error between the rotation speed detection value ω _FB and the target value ω _REF . The speed controller 110 generates a control command value V _CTRL corresponding to the error signal δω.

When the motor 202 is controlled in an open loop, the open loop controller 104 generates a constant start command value V _START that can stabilize the rotational speed of the motor 202 at the target value ω _REF in a steady state.

The drive voltage controller 112 (ii) applies a drive voltage Vm corresponding to the control command value V _CTRL to the motor 202 in the first mode φ1, and (ii) drives according to the start command value V _START in the second mode φ2. A voltage Vm is applied to the motor 202.

The drive voltage controller 112 is set to the second mode φ2 when starting the motor 202 from the stopped state of the motor 202, and increases the rotation speed of the motor 202 in an open loop. Then the rotation speed of the motor 202 after a certain degree is increased, the driving voltage controller 112 is set to the first mode .phi.1, approximate the rotational speed of the motor 202 to the target value omega _REF by feedback control.

It is desirable that the feedback controller 102 be operated to generate the control command value V _CTRL while the drive voltage controller 112 is set to the second mode φ2.

When the motor 202 is represented as a first-order lag system, the rotational speed ω of the motor 202 when a constant drive voltage Vm is applied increases according to the following equation (1) corresponding to the step response.
ω = Vm / Kt × {1-e ^{(−t / τ)} } (1)
Kt is a parameter specific to the motor 202 and the drive system.

The open loop controller 104 may generate the start command value _VSTART so that the drive voltage Vm satisfying the expression (2) is obtained.
Vm = Kt × ω _REF (2)

Assume that the following relational expression (3) holds between the drive voltage Vm generated by the drive voltage controller 112 and the control command value V _CTRL (or the start command value V _START ).
Vm = α × V _START (3)
α is a proportionality constant. In this case, the open loop controller 104 may generate the start command value V _START based on the equation (4).
V _START = Vm / α = Kt × ω _REF / α (4)

The above is the configuration of the driving circuit 100. Next, the operation will be described. FIG. 4 is an operation waveform diagram of the drive circuit 100 of FIG. Before the time t0, the motor 202 is stopped and the rotational speed ω is zero. At time t0, the target rotational speed ω _REF is set to a non-zero value. The open loop controller 104 generates a start command value V _START corresponding to the target rotational speed ω _REF . Driving voltage controller 112, between time t0 of the first period _{T 1,} is set to the second mode .phi.2, it drives the motor 202 in an open loop. In the first period _{T 1,} the rotation speed of the motor 202 rises in accordance with equation (1).

When the rotation speed of the motor is stabilized, the drive voltage controller 112 is set to the first mode at time t2. At time t2 the second period _{T 2} of the subsequent driving voltage controller 112 on the basis of the control command value _{V CTRL,} to stabilize the rotation speed of the motor 202.

During the first period _{T 1,} the feedback controller 102 is operating, the control command value _{V CTRL} corresponding to the error of the detection value omega _FB target value omega _REF of speed is generated. Therefore, at time t1, the control command value V _CTRL takes a value close to the start command value V _START , and the transition from the second mode φ2 to the first mode φ1 can be performed seamlessly, and the rotational speed ω rings. Can be prevented.

The drive voltage controller 112 may be set to the first mode φ1 after a lapse of a predetermined time τ after starting the motor 202, or after starting the motor 202, the rotation speed detection value ω _FB and the target value ω _{When the REF} error becomes smaller than the allowable value, the first mode φ1 may be set.

The above is the operation of the drive circuit 100. According to the driving circuit 100 according to this manner embodiment, in the first period T ₁ for accelerating the motor 202, the drive voltage Vm remains substantially constant value according to the start command V _START. Therefore, vibration due to feedback does not occur in the drive voltage Vm, so that noise during startup can be suppressed or reduced.

  Subsequently, a modified example of the activation sequence will be described.

In FIG. 4, the case where the stopped motor is rotated has been described, but the second mode φ <b> 2 can also be used when changing the target rotational speed ω _REF . That is, the drive voltage controller 112 is set to the second mode φ2 when the target value ω _REF of the rotation speed of the motor 202 is changed from the first value ω _REF1 to the second value ω _REF2 . The open loop controller 104 generates the start command value V _START of Expression (4) based on the changed second value ω _REF2 . Thereby, also when changing speed, a noise can be suppressed and reduced. The above-described startup sequence in FIG. 4 can be understood as a case where ω _REF1 = 0.

  FIG. 5 is another operation waveform diagram of the drive circuit 100 of FIG. Here, the motor 202 is a three-phase motor 202, and the drive voltage controller 112 can be switched between a rectangular wave energization (120 degree energization) method and a sine wave energization (180 degree energization) method.

Before the time t0, the motor 202 is stopped and the rotational speed ω is zero. At time t0, the target rotational speed ω _REF is set to a non-zero value (referred to as final target value ω _REF ). After start-up of the motor 202, the driving voltage controller 112 in the first period _{T 1} is set to the second mode .phi.2, it drives the motor 202 in 120-degree energization method. Also continues set to the second mode φ2 in the second period T ₂ which follow, to drive the motor 202 in 180-degree energization method. In the third period _{T 3} that follows the second time period _{T 2,} the drive voltage controller 112 is set to the first mode .phi.1, it drives the motor 202 in 180-degree energization method.

Open-loop controller 104, during the first period _{T 1,} start the command value _{V START,} when controlling the motor 202 in an open loop, lower sub-target than the final target value omega _REF rotational speed of the motor 202 at steady state A value V _START1 that can be stabilized to the value ω _SUB is set.
V _START1 = Vm / α = Kt _{(120 °)} × ω _SUB / α
Kt _{(120 °)} is a parameter corresponding to 120-degree energization.

Further, the open loop controller 104 stabilizes the rotational speed of the motor 202 to the final target value ω _REF in a steady state when the start command value V _START is controlled by the open loop during the second period T _2. Set to possible value V _START2 .
V _START2 = Vm / α = Kt _{(180 °)} × ω _REF / α

The first period T ₁ may be a period from the start of activation until a predetermined time τ elapses, or a period from the start of activation until the rotation speed detection value ω _FB reaches the predetermined value ω _TH. Also good. The predetermined time τ or the predetermined value ω _TH can be obtained from the intersection point P between the 120-degree energization waveform and the 180-degree energization waveform.

  According to the above activation sequence, noise can be reduced even in the drive circuit 100 that can switch between the 120-degree energization method and the 180-degree energization method.

  The present invention is understood as the block diagram and circuit diagram of FIG. 3 or extends to various devices, circuits, and methods derived from the above description, and is not limited to a specific configuration. Hereinafter, more specific configuration examples will be described in order not to narrow the scope of the present invention but to help understanding and clarify the essence and circuit operation of the present invention.

FIG. 6 is a circuit diagram of a control system 200a including a drive circuit 100a that drives a three-phase motor. The control system 200a includes Hall elements 204 to 208 in addition to a drive circuit 100a and a brushless three-phase motor (simply called a motor) 202. The hall elements 204 to 208 generate periodic hall signals S1 _{U to} S1 _W according to the position of the rotor of the motor 202, respectively. Each hall signal S1 includes a pair of signals having opposite polarities.

The drive circuit 100a receives an input clock CLKREF having a frequency corresponding to the target rotational speed ω _REF of the motor 202 from the outside, and stabilizes the rotational speed of the motor 202 to the target rotational speed ω _REF .

The drive voltage controller 112 includes a pulse width modulator 14, a logic circuit 16, and a drive stage 20. Based on the control signal S <b> 2 from the logic circuit 16, the driving stage 20 applies driving voltages S <b> 3 _{U to} S <b> 3 _V to three-phase coils (not shown) of the motor 202 to drive the motor 202. The drive stage 20 includes a three-phase inverter 22 and its driver 24.

Hall comparator HCMP1 compares the Hall signal S1 _U from the hall element 204 of the U-phase, and generates a rectangular signal S5 _U of the U phase. Hall comparator HCMP2, HCMP3 similarly is, V-phase, rectangular signal _S 5V of _W-phase, to produce an _{S 5W.} Rectangular signals S5 _{U to} S5 _W indicate the position of the rotor of the motor 202, and are supplied to the logic circuit 16 of the drive voltage controller 112.

  The drive voltage controller 112 drives the motor 202 by a 120-degree energization method. The logic circuit 16 generates a control signal S2 based on the rectangular signal S5 from the Hall comparators HCMP1 to HCMP3, and switches the coil that supplies the drive current (commutation control).

The drive voltage controller 112 drives the motor 202 with PWM (Pulse Width Modulation). Control command value V _CTRL from feedback controller 102 and start command value V _START from open loop controller 104 are duty command values for PWM drive.

The pulse width modulator 14 generates a PWM signal S _PWM having a duty ratio corresponding to the control command value V _CTRL in the first mode φ1 and the start command value V _START in the second mode φ2. The logic circuit 16 generates the control signal S2 so that the transistors constituting the inverter 22 are switched according to the _PWM signal SPWM.

The feedback controller 102 includes a speed detector 106, an error detector 108, and a speed controller 110. The error detector 108 includes a speed discriminator 76. The speed discriminator 76 receives an internal clock signal CLKINT having a frequency corresponding to the actual number of revolutions of the motor 202 and an input clock CLKREF having a frequency corresponding to the target value ω _REF , and these frequencies are used as an error signal δω. The acceleration signal ACC and the deceleration signal DEC corresponding to the error are generated.

In this embodiment, motor 202 is FG magnetized, and a predetermined number (for example, 45 times) of FG signals are generated per one rotation of motor 202. The speed detector 106 generates an internal clock CLKINT by multiplying the frequency of the FG signal obtained from the motor 202 (for example, 1024 times). The speed detector 106 may include an FG amplifier that amplifies the FG signal and a PLL circuit that multiplies the output of the FG amplifier. In this case, the internal clock CLKINT has a frequency proportional to the actual rotational speed of the motor 202, and thus becomes the detected rotational speed value ω _FB .

The speed controller 110 includes an integrating amplifier 110 that integrates the acceleration signal ACC and the deceleration signal DEC. The output of the speed controller 110 is a control command value V _CTRL , which is a duty ratio command value.

The open loop controller 104 receives the input clock CLKREF and generates a start command value V _START corresponding to the frequency. For example open loop controller 104, a frequency counter for measuring the frequency of the input clock CLKREF, the A / D converter for converting the count value of the frequency counter to an analog voltage (startup command value _{V START),} may contain. By optimizing the count speed of the frequency counter and the reference voltage of the A / D converter, it is possible to generate a start command value V _START that satisfies Equation (4). The configuration of the open loop controller 104 is not particularly limited.

  The sequencer 30 generates a mode setting signal S7 for controlling the mode of the drive voltage controller 112. The sequencer 30 can be configured by a combination of an analog timer, a digital timer, a state machine, etc., but the configuration is not particularly limited.

  FIG. 7 is a waveform diagram showing the 120-degree energization method. The high-side arm gate signals UH, VH, WH and the low-side arm gate signals UL, VL, WL of each phase inverter are switched on and off in a predetermined order at the edge timing of the rectangular signal S5. It remains on for 120 degrees in electrical angle. The high-side arm of each phase may be PWM controlled during its on period.

  The above is the configuration of the driving circuit 100a. According to this drive circuit 100a, the three-phase motor 202 can be started with low noise.

  FIG. 8 is a circuit diagram of a drive circuit 100b that drives the motor 202 by switching between the 120-degree energization method and the 180-degree energization method. In FIG. 8, circuit blocks common to FIG. 6 can be omitted. The feedback controller 102 b includes a waveform data generation unit 12, a selector 13, a pulse width modulator 14, and a rotation speed detection circuit 50.

In the 180-degree energization method, the drive voltages S3 _{U to} S3 _W are changed according to the sine wave. The waveform data generation unit 12 generates waveform data SINU to SINW in accordance with the rotation speed of the motor 202. FIG. 8 shows only the configuration related to the U phase, but the same applies to the V phase and the W phase.

  The waveform data generation unit 12 includes a waveform memory 60 and a reading unit 62. The waveform memory 60 holds waveform data SINU having a normalized amplitude. Since the waveform data SINU to SINW are the same, the waveform memory 60 may be shared by the U, V, and W phases. The shape of the waveform data SINU to SINW is not particularly limited, and a known technique may be used.

The reading unit 62 reads the waveform data SINU in units of 60 electrical degrees while synchronizing with the rectangular signals S5 _{U to} S5 _W. The rotation speed detection information S6 from the rotation speed detection circuit 50 is input to the reading unit 62. The rotation speed detection information S6 may be data indicating the time required for the rotor of the motor 202 to rotate by a predetermined electrical angle (for example, 60 degrees). The rotation speed detection circuit 50 may generate the rotation speed detection information S6 based on the rectangular signals S5 _{U to} S5 _W. The reading unit 62 reads the data for the electrical angle of 60 ° from the waveform data SINU so that the length of the electrical angle is 60 ° indicated by the rotation speed detection information S6.

The pulse width modulator 14 converts it into a PWM (pulse width modulation) signal S _PWMU having a duty ratio corresponding to the waveform data SINU. For example, the pulse width modulator 14 includes a D / A converter 66, an oscillator 68, and a comparator 70. The D / A converter 66 converts the waveform data SINU read from the reading unit 62 into an analog waveform signal V _SINU . The oscillator 68 generates a periodic signal V _OSC of a triangular wave or a sawtooth wave. The comparator 70 compares the periodic signal _{V OSC} and the waveform signal _{V sinU,} generates a PWM signal _{S PWMU.} The pulse width modulator 14 may be constituted by a digital circuit.

The selector 13 receives the control command value V _CTRL from the speed controller 110 and the start command value V _START from the open loop controller 104, and selects one according to the mode setting signal S7. The output signal of the selector 13 is given as a reference voltage for the D / A converter 66. Therefore, the output voltage V _SINU of the D / A converter 66 has a waveform corresponding to the waveform data SINU, and the amplitude thereof is the control command value V _CTRL or the start command value V _START.
It changes according to.

The logic circuit 16 generates U-phase gate signals UH and UL based on the PWM signal S _PWMU and the rectangular signals S5 _{U to} S5 _W. The same applies to the V phase and the W phase.

  FIG. 9 is a waveform diagram showing the 180-degree energization method. Here, an ideal sine wave is shown as the waveform data SINU to SINW, but the waveform differs depending on the modulation method (two-phase modulation, three-phase modulation). For example, in two-phase modulation, a double-cove sine wave may be used. Further, instead of the sine wave, a trapezoidal wave or a step wave obtained by simplifying it may be used.

  The period of each of the waveform data SINU to SINW must match the period of the hall signal. Therefore, the generation of the waveform data SINU to SINW requires the rotational speed detection information S6 indicating the current rotational speed of the motor. This is generated by the rotation speed detection circuit 50. The rotation speed detection circuit 50 generates waveform data SINU to SINW in units of time of 60 degrees in electrical angle. In this case, the waveform data generation unit 12 acquires the time of the electrical angle of 60 degrees as the rotation speed information indicating the rotation speed of the motor, and generates the waveform data SINU to SINW on a time scale corresponding to the rotation speed information.

  Next, the use of the drive circuit 100 will be described. FIG. 10 is a perspective view of a printer apparatus 300 including the drive circuit 100 of FIG. 6 or FIG. The printer apparatus 300 includes a paper feed mechanism (also referred to as a sheet feeder) 302 for feeding paper 304. The drive circuit 100 according to the embodiment is suitable for driving the motor 202 for controlling the paper feed mechanism 302.

  The present invention has been described based on the embodiments. This embodiment is an exemplification, and it will be understood by those skilled in the art that various modifications can be made to combinations of the respective constituent elements and processing processes, and such modifications are within the scope of the present invention. is there. Hereinafter, such modifications will be described.

(First modification)
In the drive circuit 100a of FIG. 6, a charge pump circuit may be provided instead of the integrating amplifier 78. In this case, the speed discriminator 76 generates an acceleration pulse ACC and a deceleration pulse DEC according to the speed error. The charge pump circuit may include a capacitor and a charge / discharge circuit that charges the capacitor in response to the acceleration pulse ACC and discharges the capacitor in response to the deceleration pulse DEC. The voltage generated in the capacitor corresponds to the speed control signal S9.

  The speed discriminator 76, the selector 64, and the FG amplifier 72 in the previous stage from the charge pump circuit may be provided outside the drive circuit 100a. That is, the drive circuit 100a may include a terminal that receives the acceleration pulse ACC and the deceleration pulse DEC.

(Second modification)
In the embodiment, the control system 200 including the Hall elements 204 to 208 has been described, but the present invention is not limited thereto. The Hall element may be provided only in any one of the U to W phases.

  Alternatively, the present invention is also applicable to a sensorless control system 200 in which the Hall elements 204 to 208 are omitted. In this case, instead of the Hall elements 204 to 208, a BEMF comparator for detecting a back electromotive force (BEMF) for detecting a zero cross point based on a comparison between the terminal voltage of the coil and the midpoint voltage may be provided.

(Third Modification)
The detection method of the rotation speed by the rotation speed detection circuit 50 is not particularly limited. As shown in FIG. 7, when the motor 202 is FG magnetized and an FG signal is generated, the rotation speed detection circuit 50 may generate the rotation speed detection information S6 based on the FG signal. Alternatively, when the drive circuit 100 includes a comparator for detecting a zero cross based on the back electromotive force, the rotation speed detection information S6 may be generated based on the output period of the BEMF comparator.

(Fourth modification)
The motor 202 may be a single phase motor. In the embodiment, the drive circuit 100a that drives the motor 202 by PMW has been described with reference to FIG. 6, but the present invention is not limited thereto, and the motor 202 may be linearly driven.

(5th modification)
In the embodiment, switching from the 120-degree energization method to the 180-degree energization method has been described, but the present invention is not limited thereto. For example, a 150-degree energization method may be adopted as the sine wave energization method.

(Sixth Modification)
The type of the motor 202 is not particularly limited, and may be a fan motor used for a cooling device.

  Although the present invention has been described using specific terms based on the embodiments, the embodiments only illustrate the principles and applications of the present invention, and the embodiments are defined in the claims. Many variations and modifications of the arrangement are permitted without departing from the spirit of the present invention.

DESCRIPTION OF SYMBOLS 100 ... Drive circuit, 102 ... Feedback controller, 104 ... Open loop controller, 106 ... Speed detector, 108 ... Error detector, 110 ... Speed controller, 112 ... Drive voltage controller, 200 ... Control system, 202 ... Motor, 204, 206, 208 ... Hall elements, 10 ... Control signal generator, 12 ... Waveform data generator, 13 ... Selector, 14 ... Pulse width modulator, 16 ... Logic circuit, 20 ... Drive stage, 22 ... Inverter, 24 ... Driver, 30 ... Sequencer, 50 ... Revolution detection circuit, HCMP ... Hall comparator, S1 ... Hall signal, S2 ... Control signal, S3 ... Drive voltage, S5 ... Rectangular signal, S6 ... Revolution detection information, S7 ... Mode setting signal, S8 ... Pulse signal, S9 ... Speed control signal, 60 ... Waveform memory, 62 ... Reading unit, 4 ... selectors, 66 ... D / A converter, 68 ... oscillator 70 ... comparator, 76 ... speed discriminator, 78 ... integrating amplifier, 300 ... printer, 302 ... paper feed mechanism, 304 ... paper.

Claims (17)

A motor drive circuit for driving a motor,
A feedback controller that adjusts a control command value by feedback control so that a detected value of the rotation speed of the motor approaches a target value;
When the motor is controlled in an open loop, an open loop controller that generates a constant start command value that can stabilize the rotation speed of the motor at the target value in a steady state;
(Ii) a drive voltage controller that applies a drive voltage according to the control command value to the motor in the first mode, and (ii) a drive voltage controller that applies a drive voltage according to the start command value to the motor in the second mode; ,
With
The motor drive circuit, wherein the drive voltage controller is set to the second mode when starting the motor from a stopped state of the motor. The open loop controller uses the unique parameter Kt, and the response waveform of the rotational speed ω of the motor is
ω = Vm / Kt × {1-e ^{(−t / τ)} }
When represented by
Vm = Kt × ω _REF
The motor drive circuit according to claim 1, wherein the start command value is generated so that a drive voltage Vm satisfying the above condition is obtained.   The drive voltage controller is set to the second mode when the target value of the rotation speed of the motor is changed from a first value to a second value. Motor drive circuit.   4. The motor drive circuit according to claim 1, wherein the drive voltage controller is set to the first mode after a predetermined time has elapsed after starting the motor. 5.   The drive voltage controller is set to the first mode when an error between the detected value of the rotation speed and the target value becomes smaller than an allowable value after starting the motor. The motor drive circuit according to any one of the above. The motor is a three-phase motor;
The drive voltage controller can be switched between a 120-degree energization method, a 180-degree energization method, or a 150-degree energization method, and is set in the second mode in the first period after the start of the motor, The motor is driven, the second mode is set in the subsequent second period, the motor is driven by a 180-degree energization method or a 150-degree energization system, and the first period in the third period following the second period. Set to the mode, the motor is driven by a 180-degree energization method or a 150-degree energization method,
The open loop controller is
During the first period, when the motor is controlled in an open loop, the start command value is set to a value that can stabilize the rotational speed of the motor at a sub target value lower than the target value in a steady state,
The start command value during the second period is set to a value that can stabilize the rotational speed of the motor at the target value in a steady state when the motor is controlled in an open loop. Item 6. The motor drive circuit according to any one of Items 1 to 5.   The motor drive circuit according to claim 6, wherein the first period is a period from a start of starting until a predetermined time elapses.   The motor drive circuit according to claim 6, wherein the first period is a period from the start of startup until the detected value of the rotational speed reaches a predetermined value. The feedback controller is
An error detector that generates an error signal corresponding to an error between the detected value of the rotational speed and the target value;
A speed controller that generates the control command value according to the error signal;
The motor drive circuit according to claim 1, further comprising: The drive voltage controller drives the motor with PWM (Pulse Width Modulation),
The motor drive circuit according to any one of claims 1 to 9, wherein the control command value and the start command value are duty command values for PWM driving. The error detector receives an internal clock signal having a frequency corresponding to the number of rotations of the motor and an input clock having a frequency corresponding to the target value, and accelerates according to an error of those frequencies as the error signal. A speed discriminator that generates a signal and a deceleration signal;
The motor drive circuit according to claim 9, wherein the speed controller includes an integration amplifier that integrates the acceleration signal and the deceleration signal.   The motor driving circuit according to claim 11, wherein the motor is FG magnetized, and the internal clock is generated by multiplying a frequency of an FG signal obtained from the motor. The drive voltage controller is
A pulse width modulator that generates a pulse width modulation signal having a duty ratio according to the control command value or the start command value;
An inverter for applying a driving voltage to the motor in accordance with the pulse width modulation signal;
The motor drive circuit according to claim 1, comprising:   The motor driving circuit according to claim 1, wherein the motor driving circuit is monolithically integrated on one semiconductor substrate. A three-phase motor,
The motor drive circuit according to any one of claims 1 to 14, which drives the three-phase motor;
A paper feed mechanism to which the three-phase motor is attached;
A printer apparatus comprising: A method for starting a stopped motor so that the rotation speed becomes a target value,
When the motor is controlled in an open loop, generating a constant start command value capable of stabilizing the rotation speed of the motor at a target value in a steady state;
Driving the motor with a duty ratio according to the start command value in a first period after starting the motor;
Generating a control command value so that a detected value of the rotational speed of the motor approaches the target value in a second period after the first period;
Driving the motor at a duty ratio according to the control command value in the second period;
A method comprising the steps of: A method of starting a stopped three-phase motor so that its rotational speed becomes a final target value,
When the three-phase motor is controlled in an open loop in the first period after the start of the motor, a constant first value that can stabilize the rotational speed of the motor to a sub target value lower than the final target value in a steady state. Generating a start command value;
In the first period, driving the motor with a 120-degree energization method at a duty ratio according to the first start command value;
In a second period following the first period, when the three-phase motor is controlled in an open loop, a constant second start command value that can stabilize the motor speed at the final target value in a steady state is generated. And steps to
Driving the motor in a 180 degree energization method or a 150 degree energization method at a duty ratio according to the second start command value in the second period;
Generating a control command value so that a detected value of the rotational speed of the motor approaches the final target value in a third period following the second period;
Driving the motor at a duty ratio according to the control command value in the third period;
A method comprising the steps of:

Images