CN101411054B

CN101411054B - Motor drive circuit, method, and disc device using the same

Info

Publication number: CN101411054B
Application number: CN2007800113277A
Authority: CN
Inventors: 大田黑义人
Original assignee: Rohm Co Ltd
Current assignee: Rohm Co Ltd
Priority date: 2006-03-29
Filing date: 2007-03-16
Publication date: 2012-06-27
Anticipated expiration: 2027-03-16
Also published as: JP4880339B2; JP2007267552A; CN101411054A

Abstract

A motor drive circuit compares a back electromotive voltage generated in a coil of the motor with a middle point voltage of the coil to detect a zero cross point and outputs a back electromotive detection signal. According to the back electromotive detection signal, the motor drive circuit controls ON/OFF of a plurality of switching elements so as to adjust current flowing into the coil of the motor. Prior to the detection of the zero cross point, a window signal which is outputted for a period of the back electromotive detection signal multiplied by a predetermined coefficient sets the switching circuit to a high-impedance state. With this configuration, it is possible to adaptively set the length and the timing of the non-drive period of the switching circuit according to the motor rotation state.

Description

Motor-drive circuit and method and the dish device that has used it

Technical field

The present invention relates to control the technology of the rotation of rotor, the particularly motor rotating drive circuit of control motor, said motor comprises stator with a plurality of coils and the rotor with magnetic.

Background technology

In the electronic equipment that uses portable (portable) CD (Compact Disc), DVD dish-type media such as (Digital VersatileDisc),, use brshless DC motor for making this disc spins.Brushless direct-current (DC) motor generally comprises rotor with permanent magnet and the stator with polyphase winding of star connection, Y connection, and the electric current that offers coil through control comes coil magnetization, and rotor is driven with respect to the relative rotation of stator.Brushless DC motor is the position of rotation of detection rotor, generally has transducers such as Hall element or optical encoder, according to the detected next position of transducer, switches the electric current that offers each phase coil, gives rotor suitable torque.

For making motor miniaturization more, also propose to have the electric machine without sensor (for example with reference to patent documentation 1,2) of the position of rotation that does not use transducer ground detection rotors such as Hall element.Electric machine without sensor is the current potential (to call mid-point voltage in the following text) of the wiring of the mid point through the instrumentation motor for example, keeps watch on the back electromotive force (induced voltage) that coil produced, and through detecting and the mid-point voltage zero cross point that equates that becomes obtains positional information.

In the driving of such electric machine without sensor,, need to set non-driven state according to the timing (timing) that produces zero cross point for keeping watch on the back electromotive force of certain phase coil.In this non-driven state, the driver that links to each other with phase coil is stopped switch drive, is set to high-impedance state.Particularly in the driving of 180 degree step modes etc., owing to always flow through electric current in the phase coil,, predict the outcome according to this and set high-impedance state so need prediction that the timing of zero cross point takes place.

1. for example disclose that (Phase Locked Loop: phase-locked loop) mode realizes being set at the method for the timing of high-impedance state with PLL in the patent documentation 5.

2. in addition, also record correlation technique in the patent documentation 3.

3. in addition; Known have in the driving of electric machine without sensor; With pulse width modulation (Pulse WidthModulation, below also claim PWM) mode gently control flows cross the electric current of phase coil, make its technology that becomes sinusoidal wave shape or arch bridge shape (for example with reference to patent documentation 3,4 etc.).

Patent documentation 1: the spy opens flat 3-No. 207250 communiques

Patent documentation 2: the spy opens flat 10-No. 243685 communiques

Patent documentation 3: the spy opens flat 11-No. 75388 communiques

Patent documentation 4: the spy opens flat 11-No. 341870 communiques

Patent documentation 5: the spy opens communique 2001-No. 190085

Summary of the invention

(inventing problem to be solved)

1. at this, when setting non-driven state, if set longlyer during will being set at the non-driving of high-impedance state, though then can detect zero cross point reliably, the electrorheological that flows through motor coil gets discontinuous, can cause increasing from the noise that motor produces.Therefore, hope during the non-driving shortly as far as possible, but if too short, then can produce the inconsistent situation of timing during zero cross point and the non-driving.If such situation takes place, can cause that then the rotation of motor is irregular, can cause the problem such as stop of motor when the poorest.Therefore, need follow the trail of in the change of rotating speed of motor and load ground, the setting during carrying out non-driving adaptively.

2. in addition, be to make the electric current that flows through motor coil be sinusoidal wave shape or the variation continuously of arch bridge shape ground sometimes, and control the voltage that imposes on motor coil with pulse modulation.(a)～(c) of Fig. 7 is the sequential chart of situation of the detection of the zero cross point of expression when carrying out pulse modulation and driving.(a) expression of Fig. 7 is by the signal PWM after the pulse modulation; (b) expression of this figure becomes phase voltage (the following back electromotive force Vu that also claims) and the mid-point voltage Vcom that is produced in the coil of zero cross point detected object, the oscillogram of (c) expression back electromotive force detection signal BEMF_EDGE of this figure.

Shown in Fig. 7 (b); Among the back electromotive force Vu that in the coil that becomes the zero cross point detected object, is produced; From the timing that is changed to ON by the OFF of the signal after the pulse modulation shown in this figure (a), perhaps from the timing of ON to the OFF transformation, noise component(s) appears.Because this noise component(s), relatively phase voltage Vu and mid-point voltage Vcom and high level and low level appear in back electromotive force detection signal repeatedly that obtain are zero cross point by erroneous detection.The erroneous detection of zero cross point that is to say the erroneous detection of rotor-position, so can cause problems such as running accuracy variation, malrotation.

3. in addition, for crossing the electric current of phase coil with PWM mode control flows, need be with the rotation status of motor, be that the position relation of rotor and stator is synchronously controlled sinuous drive current.If the rotation status of the control of drive current and motor is asynchronous, the rotation that noise or motor then can occur stops such problem.

1. the present invention designs in view of such situation, and one of its purpose is to provide a kind of can set length and motor-drive circuit regularly during the non-driving adaptively according to the rotation status of motor.

2. another object of the present invention is to provide a kind of technology of erroneous detection of the zero cross point when preventing that motor carried out pulse modulated the driving.

3. a further object of the present invention is to provide a kind of motor-drive circuit that can suitably carry out sine wave drive according to the rotation status of motor.

(being used to solve the means of problem)

1. a scheme of the present invention relates to a kind of motor-drive circuit that provides drive current to drive to polyphase machine, comprising:

A plurality of switching circuits of establishing by each coil of above-mentioned polyphase machine respectively apply high level or low level voltage to an end of the coil that connected;

Counter electromotive force detection circuit, the back electromotive force that is produced at least one coil with above-mentioned polyphase machine and the mid-point voltage of coil compare, and detect zero cross point, output back electromotive force detection signal;

The window generative circuit, before above-mentioned counter electromotive force detection circuit carries out the detection of zero cross point, output the cycle of the back electromotive force detection signal that above-mentioned counter electromotive force detection circuit is exported multiply by pre-determined factor during in become the window signal of predetermined level;

ON-OFF control circuit; Based on back electromotive force detection signal from above-mentioned counter electromotive force detection circuit output; Control the on off state of above-mentioned a plurality of switching circuits, regulate the electric current that is flow through in the coil of above-mentioned polyphase machine, and; From the window signal of above-mentioned window generative circuit be above-mentioned predetermined level during stop the switch motion of said switching circuit, said switching circuit is set at high-impedance state;

When establishing above-mentioned pre-determined factor when being α (α is the real number that satisfies 0＜α＜1); Above-mentioned window generative circuit will from above-mentioned counter electromotive force detection circuit export certain back electromotive force detection signal, through the cycle of above-mentioned back electromotive force detection signal multiply by coefficient (1-α) during after the moment, make above-mentioned window signal be changed to above-mentioned predetermined level;

Then, be triggering to have exported next back electromotive force detection signal from above-mentioned counter electromotive force detection circuit, make above-mentioned window signal become the level that is different from above-mentioned predetermined level;

Above-mentioned window generative circuit comprises:

The pulse signal generative circuit receives from the above-mentioned back electromotive force detection signal of above-mentioned counter electromotive force detection circuit output, the n that generates this back electromotive force detection signal doubly (n is the integer more than 2) frequency pulse signal and

Timing setting portion; Reception is from the above-mentioned back electromotive force detection signal of above-mentioned counter electromotive force detection circuit with from the above-mentioned pulse signal of above-mentioned pulse signal generative circuit; After detecting certain back electromotive force detection signal; When having detected m (m is the integer that satisfies m＜n) above-mentioned pulse signal, make above-mentioned window signal become above-mentioned predetermined level, and after make above-mentioned window signal become the level that is different from above-mentioned predetermined level when detecting next back electromotive force detection signal

Wherein, α=1-m/n.

Timing setting portion can have the adjusting device of integer m.At this moment, the kind of the motor that can basis links to each other with this motor-drive circuit etc. change integer m, so can realize stable motor-driven.

The pulse signal generative circuit can comprise: frequency counter, the frequency of mensuration back electromotive force detection signal; Clock signal generation portion, the n of the frequency that the generated frequency counter is measured is the pulse signal of (n is the integer more than 2) frequency doubly.Frequency counter can be transfused to certain back electromotive force detection signal rise till be transfused to next back electromotive force detection signal during in, the clock signal of preset frequency is counted, measure the cycle of back electromotive force detection signal.

The frequency values in past K time (K is the integer more than 1) that clock signal generation portion can measure frequency counter carries out computing, according to the result of computing, and the frequency of the pulse signal that setting should generate.

Clock signal generation portion can have the adjusting device of integer K.In this case, set K more little, the gain of feedback loop is just risen more, so can set K big more with setting higherly to the tracking property of rotating speed of motor change, the gain of feedback loop just descends more, so can improve the stability of ring.Therefore, through set the value of K according to kind, rotating speed, the type of drive of motor, can realize best motor-driven.

The pulse signal generative circuit can also comprise: storage part, preserve the frequency values of L time (L is the integer that satisfies L >=K) in the past; Operational part based on the frequency values that storage part is preserved, is carried out predetermined computing.Clock signal generation portion can generate the pulse signal with the operation result correspondent frequency of operational part.Storage part can be a L level shift register.

Up-to-date K time frequency values carries out computing in L time the frequency values that operational part can be preserved storage part, decides the frequency of pulse signal.

Timing setting portion can comprise: counter; Reception is from the back electromotive force detection signal of counter electromotive force detection circuit output and the pulse signal of exporting from the pulse signal generative circuit, and the unlatching that output has become predetermined level after detecting certain back electromotive force detection signal, when having counted m pulse signal is along signal; The window signal efferent, output is becoming predetermined level during along signal, when detecting next back electromotive force detection signal, is becoming the window signal of the level that is different from predetermined level afterwards from the unlatching of counter output predetermined level.

Motor-drive circuit can be integrated on a Semiconductor substrate.So-called " integrating "; All structure important documents that comprise circuit all are formed on the situation on the Semiconductor substrate; And the primary structure important document of circuit situation about being integrated, also can a part of resistor, capacitor etc. be arranged on the outside of Semiconductor substrate for the regulating circuit constant.Through motor-drive circuit being integrated into a LSI, can reduce circuit area.

Another program of the present invention is a kind of dish device.This device comprises: the spindle motor that makes disc spins; The above-mentioned motor-drive circuit of drives spindle motor.

According to this scheme, can be as much as possible with the switching circuit that links to each other with the coil of motor become high resistant during set shortlyer, so can shorten the electric current that is flow through in the coil of motor occur discontinuous during, can reduce the noise that spindle motor sends.

Another scheme of the present invention is a kind of method.This method is the driving method that polyphase machine is provided drive current; Comprise: the back electromotive force that is produced at least one coil with polyphase machine and the mid-point voltage of coil compare; Detect zero cross point, the back electromotive force of output back electromotive force detection signal detects step; According to the back electromotive force detection signal, an end of each coil of polyphase machine is applied high level or low level voltage, regulate the step of the electric current that is flow through in the coil of polyphase machine; Before back electromotive force detects the detection of the zero cross point in the step, after multiply by pre-determined factor in the cycle of back electromotive force detection signal during in, the circuit that will be connected with coil is set at the step of high-impedance state.

2. a scheme of the present invention relates to a kind of motor-drive circuit that provides drive current to drive to polyphase machine.This motor-drive circuit comprises: a plurality of switching circuits of establishing by each coil of polyphase machine respectively apply high level or low level voltage to an end of the coil that connected; The pulse-modulated signal generative circuit generates the pulse-modulated signal of change in duty cycle at least according to the target torque of polyphase machine; Counter electromotive force detection circuit, the back electromotive force that is produced at least one coil with polyphase machine and the mid-point voltage of coil compare, and detect zero cross point, output back electromotive force detection signal; ON-OFF control circuit; Reception is from the pulse-modulated signal of pulse-modulated signal generative circuit with from the back electromotive force detection signal of counter electromotive force detection circuit; Based on the back electromotive force detection signal; Control the order of the conducting cut-off state of a plurality of switching circuits, and based on pulse-modulated signal, at least one of high-side switch that a plurality of switching circuit comprised and low side switch carried out switch control.Counter electromotive force detection circuit detects regularly based on setting from the pulse-modulated signal of pulse-modulated signal generative circuit; And in the detection that sets regularly, the back electromotive force detection signal of output predetermined level when the comparative result of back electromotive force and mid-point voltage satisfies predetermined condition.

According to this scheme, can with become to back electromotive force bring noise component(s) main cause pulse-modulated signal itself synchronously, be the less timing of noise effect with the detection timing setting of zero cross point, can prevent the erroneous detection of zero cross point.So-called " pulse modulation ", be meant pulse width modulation, pulse frequency modulated, pulse position modulation etc. utilized pulse high level and low level during ratio be the modulation of the signal of change in duty cycle.

The timing that counter electromotive force detection circuit can change based on the level of pulse-modulated signal is set and is detected regularly.At this moment, can be with the timing at the edge of pulse-modulated signal or the timing setting after making the edge delay scheduled time for detecting regularly.

Counter electromotive force detection circuit can with the level of pulse-modulated signal from the corresponding level of conducting of the switch that comprised with a plurality of switching circuit to timing by corresponding level transitions, set for and detect regularly.The noise component(s) that in back electromotive force, produces owing to pulse modulation; Be after the conducting cut-off state of the switch that coil connected different with the coil of the appearance back electromotive force that becomes detected object changes, almost to become maximum under the more situation, decay gradually afterwards.Therefore, become to detect regularly, can under the less state of noise component(s), carry out the detection of zero cross point through the timing setting of conducting before changing with switch.

Counter electromotive force detection circuit can when the magnitude relationship of above-mentioned back electromotive force and above-mentioned mid-point voltage satisfies predetermined condition, be exported the back electromotive force detection signal detecting regularly.About predetermined condition, as long as according to the driving condition of motor, when back electromotive force is higher than mid-point voltage or back electromotive force set when being lower than mid-point voltage and get final product.

Counter electromotive force detection circuit can comprise: comparator compares back electromotive force and mid-point voltage; The comparison value efferent, the output signal of reception comparator, the value of output when detecting regularly.The comparison value efferent can be the latch cicuit according to the output signal of pulse-modulated signal latched comparator.

Motor-drive circuit can be integrated on a Semiconductor substrate.Through motor-drive circuit being integrated into a LSI, can reduce circuit area.

According to this scheme, can prevent the erroneous detection of the zero cross point of motor-drive circuit well, spindle motor is stably rotated.

Another scheme of the present invention is a kind of driving method that provides drive current to drive to polyphase machine.This driving method comprises: the step that generates the pulse-modulated signal of change in duty cycle at least according to the target torque of polyphase machine; The back electromotive force that is produced at least one coil with polyphase machine and the mid-point voltage of coil compare, and detect zero cross point, and the back electromotive force that generates the back electromotive force detection signal of predetermined level detects step; Control becomes the order of the coil of driven object based on the back electromotive force detection signal, and based on pulse-modulated signal, the coil that becomes driven object is applied the step of high level or low level switching signal.Back electromotive force detects step and sets detection regularly based on pulse-modulated signal, and in the detection that sets regularly, when the comparative result of back electromotive force and mid-point voltage satisfies predetermined condition, makes the back electromotive force detection signal become predetermined level.

According to this scheme, can with become to back electromotive force bring noise component(s) main cause pulse-modulated signal itself synchronously, be the less timing of noise effect with the detection timing setting of zero cross point, can prevent the erroneous detection of zero cross point.

3. a scheme of the present invention relates to a kind of motor-drive circuit that provides drive current to drive to polyphase machine.This motor-drive circuit comprises: a plurality of switching circuits of establishing by each coil of polyphase machine respectively apply high level or low level voltage to an end of the coil that connected; Counter electromotive force detection circuit, the back electromotive force that is produced at least one coil with polyphase machine and the mid-point voltage of coil compare, and detect zero cross point, the back electromotive force detection signal of output predetermined level; The pulse signal generative circuit, reception back electromotive force detection signal generates and this back electromotive force detection signal is synchronous and frequency is the pulse signal of n times (n is the integer more than 2) of back electromotive force detection signal; The sine wave signal generative circuit receives the pulse signal from the pulse signal generative circuit, and according to the control signal of this pulse signal sine wave output shape; The pulse-modulated signal generative circuit will be synthetic with the dtc signal of the target torque of indication polyphase machine from the control signal of sine wave signal generative circuit, generate and carry out pulse modulated pulse-modulated signal; ON-OFF control circuit; Reception is from the back electromotive force detection signal of counter electromotive force detection circuit with from the pulse-modulated signal of pulse-modulated signal generative circuit; Control the order of the conducting cut-off state of a plurality of switching circuits based on the back electromotive force detection signal, and at least one of high-side switch that a plurality of switching circuit comprised and low side switch carried out switch control based on pulse-modulated signal.

According to this scheme, generate and the synchronous pulse signal of back electromotive force detection signal, and generate sinuous control signal according to this pulse signal and carry out pulse modulation, so can realize and the corresponding suitable sine wave drive of rotation status.So-called " pulse modulation ", be meant pulse width modulation, pulse frequency modulated, pulse position modulation etc. utilized pulse high level and low level during ratio be the modulation of the signal of change in duty cycle.In addition, said in this manual " sinusoidal wave shape " is to comprise also that except that sine wave trapezoidal waveform etc. can make the notion of the waveform of coil current smooth variation.

The sine wave signal generative circuit can comprise the storage part of preserving sinuous control signal, and reads sinuous control signal successively according to pulse signal and export.At this moment, be directly proportional in the cycle of sinuous control signal exactly with the frequency of pulse signal.

The pulse-modulated signal generative circuit can comprise: synthetic portion, the composite signal after output is synthesized control signal and dtc signal with the phase multiplication; Pulse modulator will compare with predetermined periodic signal from the composite signal of synthetic portion, generates the pulse-modulated signal that duty ratio changes according to its magnitude relationship.

The pulse signal generative circuit can comprise: frequency counter, the frequency of mensuration back electromotive force detection signal; Clock signal generating circuit, the n of the frequency that the generated frequency counter is measured is the pulse signal of (n is the integer more than 2) frequency doubly.

The frequency values in past K time (K is the integer more than 1) that clock signal generating circuit can be measured frequency counter carries out computing, and sets the frequency of the pulse signal that should generate according to the result of computing.

Clock signal generating circuit can have the adjusting device of integer K.In this case, set K more little, the gain of feedback loop is just risen more, so can set K big more with setting higherly to the tracking property of rotating speed of motor change, the gain of feedback loop just descends more, so can improve the stability of ring.Therefore, through set the value of K according to kind, rotating speed, the type of drive of motor, can realize best motor-driven.

The pulse signal generative circuit can also comprise: storage part, preserve the frequency values of L time (L is the integer that satisfies L >=K) in the past; Operational part based on the frequency values that storage part is preserved, is carried out predetermined computing.Clock signal generating circuit can generate the pulse signal with the operation result correspondent frequency of operational part.Storage part can be a L level shift register.

The motor-drive circuit of a scheme can also comprise the window signal generative circuit; Reception is from the back electromotive force detection signal of counter electromotive force detection circuit with from the pulse signal of pulse signal generative circuit; Output after detecting certain back electromotive force detection signal, detected m (m be satisfy m the integer of n) become predetermined level during pulse signal, when detecting next back electromotive force detection signal, become the window signal of the level that is different from predetermined level afterwards.ON-OFF control circuit can receive the window signal from the window signal generative circuit; The switch motion of the switching circuit that during this window signal is predetermined level, stops to be connected with the coil of being kept watch on back electromotive force by counter electromotive force detection circuit is set at high-impedance state.

At this moment; For carrying out the detection of zero cross point; Be used for the pulse signal that carries out sine wave drive and generate and set during the non-driving that makes the switching circuit that is connected with the coil of the detected object that becomes back electromotive force become high resistant, so can make the setting during sine wave drive and the non-driving synchronous.

The window signal generative circuit can have the adjusting device of integer m.At this moment, change integer m such as the kind of the motor that can basis links to each other with this motor-drive circuit are so can realize stable motor-driven.

The window signal generative circuit can comprise: counter; Reception is from the back electromotive force detection signal of counter electromotive force detection circuit with from the pulse signal of pulse signal generative circuit, and the unlatching that output has become predetermined level after detecting certain back electromotive force detection signal, when having counted m pulse signal is along signal; The window signal efferent, output is becoming predetermined level during along signal, when detecting next back electromotive force detection signal, is becoming the window signal of the level that is different from predetermined level afterwards from the unlatching of counter output predetermined level.

According to the dish device of this scheme, can with the rotation of spindle motor synchronously control flows cross the electric current of coil.

Another scheme of the present invention relates to a kind of driving method that provides drive current to drive to polyphase machine.This driving method comprises: the back electromotive force that is produced at least one coil with polyphase machine and the mid-point voltage of coil compare, and detect zero cross point, generate the step of the back electromotive force detection signal of predetermined level; Generate with the back electromotive force detection signal synchronously and frequency be the n step of the pulse signal of (n is the integer more than 2) doubly of back electromotive force detection signal; Generate the step of sinuous control signal according to pulse signal; Control signal is synthetic with the dtc signal of the target torque of indication polyphase machine, generate the step of having carried out pulse modulated pulse-modulated signal; Control becomes the order of the coil of driven object based on the back electromotive force detection signal, and based on pulse-modulated signal, the coil that becomes driven object is applied the step of high level or low level switching signal.

Through the driving method of this scheme, can realize and the corresponding suitable sine wave drive of rotation status.

The driving method of a scheme also comprises: be created on after detecting certain back electromotive force detection signal, detected m (m be satisfy m the integer of n) become predetermined level during pulse signal, when detecting next back electromotive force detection signal, become the step of the window signal of the level that is different from predetermined level afterwards; During window signal is predetermined level, will set the step of high-impedance state for the switching circuit that is connected for the coil that detects zero cross point quilt supervision back electromotive force.

According to this driving method; For carrying out the detection of zero cross point; Be used for the pulse signal that carries out sine wave drive and generate and set during the non-driving that makes the switching circuit that is connected with the coil of the detected object that becomes back electromotive force become high resistant, so can make the setting during sine wave drive and the non-driving synchronous.

(invention effect)

1. through a scheme of the present invention, can set the length and regularly during the non-driving adaptively according to the rotation status of motor.

2. through another program of the present invention, can when motor being carried out the pulse modulation driving, detect zero cross point exactly.

3. through another scheme of the present invention, can be according to the rotation status of motor and suitably carry out sine wave drive.

Description of drawings

Fig. 1 is the block diagram of structure of the motor-drive circuit of expression the 1st execution mode.

Fig. 2 is the block diagram of structure example of the part of expression motor-drive circuit.

Fig. 3 is the block diagram of the structure example of indicating impulse signal generating circuit and timing setting portion.

(a) of Fig. 4～(1) is the sequential chart of action of the motor-drive circuit of expression execution mode.

(a)～(d) of Fig. 5 is the sequential chart that expression generates the appearance of window signal WINDOW.

Fig. 6 is the block diagram of structure of the dish device of expression motor-drive circuit that Fig. 1, Fig. 8, Figure 12 have been installed.

(a)～(c) of Fig. 7 is the sequential chart of the zero cross point of expression when carrying out pulse modulation and driving situation about detecting.

Fig. 8 is the block diagram of structure of the motor-drive circuit of expression the 2nd execution mode.

Fig. 9 is the circuit diagram of structure example of the counter electromotive force detection circuit of presentation graphs 8.

(a) of Figure 10～(1) is the sequential chart of action of the motor-drive circuit of expression the 2nd execution mode.

(a)～(e) of Figure 11 is the oscillogram of the zero cross point of the motor-drive circuit of expression the 2nd execution mode situation about detecting.

Figure 12 is the block diagram of structure of the motor-drive circuit of expression the 3rd execution mode.

Figure 13 is the circuit diagram of structure of sine wave signal generative circuit and the pwm signal generative circuit of expression Figure 12.

Figure 14 is the block diagram of structure of the pulse signal generative circuit of expression Figure 12.

Figure 15 is the circuit diagram of structure of the window signal generative circuit of expression Figure 12.

(a) of Figure 16～(1) is the sequential chart of action of the motor-drive circuit of expression the 3rd execution mode.

(a)～(e) of Figure 17 is the sequential chart that expression generates the appearance of window signal WINDOW and sinuous control signal CNT.

Embodiment

Below, based on preferred embodiment with reference to description of drawings the present invention.Mark identical label for the identical or equivalent configurations important document shown in each accompanying drawing, parts, processing, and suitably omit the explanation of repetition.In addition, execution mode is an illustration, and non-limiting the present invention, and all characteristics and the combination thereof recorded and narrated in the execution mode not necessarily are exactly substantive characteristics of the present invention.

(the 1st execution mode)

Fig. 1 is the block diagram of structure of the motor-drive circuit 100 of expression the 1st execution mode.100 couples of non sensor brushless DC of motor-drive circuit motor (hereinafter to be referred as " motor 110 ") provides drive current, controls its rotation.In this execution mode, the motor 110 that becomes driven object is three-phase DC motors of the coil Lu that comprises U phase, V phase, W phase, Lv, Lw.

Motor-drive circuit 100 comprises switching circuit 10u, 10v, 10w, counter electromotive force detection circuit 20, ON-OFF control circuit 30, the window generative circuit 40 that is collectively referred to as switching circuit 10.Motor-drive circuit 100 is used as function IC and is integrated on the Semiconductor substrate.For example motor-drive circuit 100 carries out PWM (Pulse Width Modulation: pulse width modulation) drive, make the electric current that flows through each phase coil become arch bridge shape or sinusoidal wave shape with 180 degree step modes.

Switching circuit 10u, 10v, 10w are respectively by each coil Lu of motor 110, Lv, Lw and establish.Switching circuit 10u, 10v, 10w for example comprise the high-side switch and the low side switch ground that are connected in series between supply voltage and the earthing potential and constitute, and the tie point of two switches links to each other with coil.The control terminal of high-side switch and low side switch is transfused to drive signal DRV_H (U, V, W) and drive signal DRV_L (U, V, W) respectively.Switching circuit 10u, 10v, 10w are the voltage that under the state of conducting an end of the coil that connected is applied high level at high-side switch, at low side switch are to apply low level voltage under the state of conducting.In addition, end simultaneously, be set to high-impedance state through high-side switch and low side switch.

The back electromotive force that is produced in counter electromotive force detection circuit 20 at least one coil with motor 110 is compared with the mid-point voltage of coil, detects zero cross point, output back electromotive force detection signal BEMF_EDGE.In this execution mode, counter electromotive force detection circuit 20 is kept watch on back electromotive force Vu and the mid-point voltage Vcom that is produced among the U phase coil Lu, is created on Vu>become the back electromotive force detection signal BEMF_EDGE of high level during Vcom.The back electromotive force detection signal BEMF_EDGE that is generated is outputed to ON-OFF control circuit 30 and window generative circuit 40.

ON-OFF control circuit 30 is based on the back electromotive force detection signal BEMF_EDGE from counter electromotive force detection circuit 20 outputs; Control the conducting cut-off state of a plurality of switching circuit 10u, 10v, 10w order, be on off state, regulate the electric current of the coil flow through motor 110.ON-OFF control circuit 30 comprises driving timing generative circuit 32 and drive signal combiner circuit 34.

Driving timing generative circuit 32 is transfused to back electromotive force detection signal BEMF_EDGE.Driving timing generative circuit 32 generates the drive signal DRV in 1/6 cycle of the cycle T p1 with back electromotive force detection signal BEMF_EDGE.Drive signal combiner circuit 34 is according to the driving condition of drive signal DRV control switch circuit 10u, 10v, 10w.For example, drive signal combiner circuit 34 carries out pulse width modulation with the offset of sinusoidal ripple and the pulse signal that obtains and drive signal DRV are synthetic, exports to switching circuit 10u, 10v, 10w.

Window generative circuit 40 carries out before zero cross point detects at counter electromotive force detection circuit 20, output the cycle T p1 of the back electromotive force detection signal BEMF_EDGE that counter electromotive force detection circuit 20 is exported multiply by predetermined coefficient α (α satisfies 0 < α < 1 real number) during (become the window signal WINDOW of predetermined level in the Tp3=Tp1 * α).In this execution mode, predetermined level is a high level.

Window generative circuit 40 is transfused to the back electromotive force detection signal BEMF_EDGE from counter electromotive force detection circuit 20.Window generative circuit 40 multiply by from certain back electromotive force detection signal BEMF_EDGE of counter electromotive force detection circuit 20 output, through the cycle T p1 of back electromotive force detection signal BEMF_EDGE coefficient (1-α) during after, make window signal WINDOW become high level.Afterwards, window generative circuit 40 is triggering to have exported next back electromotive force detection signal BEMF_EDGE from counter electromotive force detection circuit 20, the level that window signal WINDOW is become be different from predetermined level, is low level.

Window signal WINDOW is outputed to the drive signal combiner circuit 34 of ON-OFF control circuit 30.Drive signal combiner circuit 34 window signal WINDOW be high level during, the switch motion of the switching circuit 10u that stops to be connected with the terminal that is produced as the back electromotive force Vu that detects zero cross point and should keep watch on is set at high-impedance state.That is, be to detect zero cross point, window signal WINDOW be high level during deliberately be set at the phase of not carrying out driving.In this execution mode, among the Tp3, U is set to the phase of not carrying out driving mutually during non-driving.

Fig. 2 is the block diagram of structure example of the part of expression motor-drive circuit 100.Counter electromotive force detection circuit 20 is comparators, and back electromotive force Vu and mid-point voltage Vcom that coil Lu is appeared compare, and output is at Vu>become high level during Vcom, <become low level back electromotive force detection signal BEMF_EDGE during Vcom at Vu.

Window generative circuit 40 comprises pulse signal generative circuit 42, timing setting portion 44.Pulse signal generative circuit 42 receives from the back electromotive force detection signal BEMF_EDGE of counter electromotive force detection circuit 20 outputs, generates the pulse signal PULSE of n times of (n is the integer more than 2) frequency of this back electromotive force detection signal BEMF_EDGE.

Timing setting portion 44 receives from the back electromotive force detection signal BEMF_EDGE of counter electromotive force detection circuit 20 with from the pulse signal PULSE of pulse signal generative circuit 42.Timing setting portion 44 after detecting certain back electromotive force detection signal BEMF_EDGE, counted m (m be satisfy m the integer of n) make window signal WINDOW become high level during pulse signal PULSE.Afterwards, when detecting next back electromotive force detection signal BEMF_EDGE, make window signal WINDOW become low level.

Preferred integer m is adjustable.For example, motor-drive circuit 100 can have the register that is used to preserve integer m, and being constituted as can be from external setting-up integer m.

Fig. 3 is the block diagram of the structure example of indicating impulse signal generating circuit 42 and timing setting portion 44.Pulse signal generative circuit 42 has frequency counter 50 and clock signal generation portion 56.

Frequency counter 50 measure back electromotive force detection signal BEMF_EDGE frequency, be cycle T p1.For example frequency counter 50 is transfused to the clock signal (not shown) of preset frequency.50 pairs of frequency counters from be transfused to certain back electromotive force detection signal BEMF_EDGE to be transfused to next back electromotive force detection signal BEMF_EDGE during in clock signal count, measure the cycle T p1 of back electromotive force detection signal BEMF_EDGE.Frequency counter 50 is exported the count value COUNT that is measured as frequency values successively.

The n of the frequency that clock signal generation portion 56 generated frequency counters 50 are measured is the pulse signal PULSE of (n is the integer more than 2) frequency doubly.That is, the cycle T p2 of pulse signal PULSE is set to the 1/n of the cycle T p1 of back electromotive force detection signal BEMF_EDGE.

The frequency values COUNT in past K time (K is the integer more than 1) that 56 pairs of frequency counters 50 of clock signal generation portion are measured carries out computing, according to the result of computing, and the frequency of the pulse signal that setting should generate.Preferably corresponding with the number of the frequency values that becomes operand integer K is adjustable.

For realizing this function, pulse signal generative circuit 42 has storage part 52 and operational part 54 in the prime of clock signal generation portion 56.Storage part 52 is preserved the frequency values COUNT of L time (L is the integer that satisfies L >=K) in the past.Storage part 52 for example can be a L level shift register.Operational part 54 is carried out predetermined computing based on the frequency values that is kept in the storage part 52.Calculation process can be simple average calculating operation, also can be the weighted average computing.

The pulse signal PULSE of the operation result correspondent frequency of 56 generations of clock signal generation portion and operational part 54.For example, 54 pairs of operational parts are kept in L time the frequency values in the storage part 52 up-to-date K time frequency values and carry out computing, the frequency of decision pulse signal PULSE.Calculation process can be that K count value carried out simple average calculating operation, also can carry out the weighted average computing.Integer K is preferably variable as stated, and being constituted as can be from external setting-up.During K=1, according to the cycle T p1 of previous back electromotive force detection signal BEMF_EDGE, the cycle T p2 of setting pulse signal PULSE.

44 receptions of timing setting portion are from the back electromotive force detection signal BEMF_EDGE of counter electromotive force detection circuit 20 outputs and the pulse signal PULSE that exports from pulse signal generative circuit 42.Timing setting portion 44 comprises counter 60, window signal efferent 62.The unlatching (open) that counter 60 outputs have become high level after detecting certain back electromotive force detection signal BEMF_EDGE, when having counted m pulse signal PULSE is along signal OPEN_EDGE.Window signal efferent 62 output is becoming high level during along signal OPEN_EDGE, when detecting next back electromotive force detection signal BEMF_EDGE, is becoming low level window signal WINDOW afterwards from the unlatching of counter 60 output high level.

The as above action of the motor-drive circuit 100 of formation like this of explanation below.(a) of Fig. 4～(1) is the sequential chart of action of the motor-drive circuit 100 of expression execution mode.The longitudinal axis of (a) of this figure～(1) and transverse axis are suitably amplified, have been dwindled for understanding conveniently, and each waveform shown in it is also for understanding convenient being simplified.(a)～(c) of this figure is respectively according to switching circuit 10u, 10v, 10w, the waveform of the driving condition of the coil Lu of expression U phase, V phase, W phase, Lv, Lw.The back electromotive force detection signal BEMF_EDGE that (d) expression of this figure is detected by counter electromotive force detection circuit 20; The drive signal DRV that (e) expression of this figure is generated by driving timing generative circuit 32, the window signal WINDOW that (f) expression of this figure is generated by window generative circuit 40.And then, the high-side switch of (g) of this figure～(1) expression switching circuit 10u～10w and drive signal DRV_H, the DRV_L of low side switch.

Shown in Fig. 4 (a)～(c), in this execution mode, drive and make drive current become the arch bridge waveform.Certainly the invention is not restricted to this, also can be sinusoidal wave.In this execution mode, back electromotive force detection signal BEMF_EDGE is shown in this figure (d), and each zero cross point that intersects at back electromotive force Vu and mid-point voltage Vcom is generated.Driving timing generative circuit 32 generates the drive signal DRV shown in (e) that the cycle T p1 that makes back electromotive force detection signal BEMF_EDGE becomes this figure after 1/6 times.The drive signal DRV back electromotive force detection signal BEMF_EDGE that also can give as shown in the figure postpones Td.Should postpone Td through regulating, motor-driven is optimised.

The drive signal DRV that drive signal combiner circuit 34 is generated based on driving timing generative circuit 32 generates and to be used for the conducting of control switch circuit 10u～10w and the drive signal DRV_H that ends (U, V, W), DRV_L (U, V, W).This driving sequence is according to suitably settings such as energising angles.

The high level of drive signal DRV_HU shown in Fig. 4 (g) is corresponding to the conducting state of the high-side switch of switching circuit 10u, and low level is corresponding to cut-off state.Drive signal DRV_H shown in (h) of this figure～(1) (V, W), DRV_L (U, V, W) also are the same.And then; The conducting state of at least one of high-side switch or low side switch is by pulse width modulation; Obtain the drive waveforms shown in (a)～(c) of this figure, the high-side switch of switching circuit 10u～10w or low side switch are with higher frequency alternate repetition conducting and end.

When drive signal combiner circuit 34 is exported at each back electromotive force detection signal BEMF_EDGE, change the drive signal DRV_H of switching circuit 10u～10w, the conducting cut-off state of DRV_L according to predetermined driving sequence.

Window signal WINDOW shown in this figure (f) was become high level by window generative circuit 40 before the moment that zero cross point takes place.Drive signal combiner circuit 34 window generative circuit 40 be high level during, make the drive signal DRV_HU, the DRV_LU that output to switching circuit 10u become low level, high-side switch and low side switch are ended, become high-impedance state.Among (g) of this figure, (j) with oblique line be expressed as detect zero cross point and be set to high-impedance state during.When an end that becomes high level, coil Lu as window signal WINDOW is set to high-impedance state, can carry out the detection of zero cross point, back electromotive force detection signal BEMF_EDGE is generated.When back electromotive force detection signal BEMF_EDGE became high level, window generative circuit 40 made window signal WINDOW become low level.

(a)～(d) of Fig. 5 is the sequential chart that expression generates the appearance of window signal WINDOW.(a) expression back electromotive force detection signal BEMF_EDGE of this figure; The pulse signal PULSE that (b) indicating impulse signal generating circuit 42 of this figure is generated; The unlatching that (c) expression counter 60 of this figure is generated is along signal OPEN_EDGE, and this figure (d) representes window signal WINDOW.

When back electromotive force detection signal BEMF_EDGE became high level, the frequency counter 50 of Fig. 3 began counting, and the count value COUNT that counts up to till the moment that back electromotive force detection signal BEMF_EDGE next time becomes high level is outputed to storage part 52.1 time count value COUNT is pass by in storage at least in the storage part 52.If the cycle of the employed clock of counting of frequency counter 50 is Tck, then the cycle T p1 of back electromotive force detection signal BEMF_EDGE becomes Tck * COUNT.Operational part 54 uses K time count value in the past to determine the cycle T p2 of pulse signal PULSE, makes Tp2=Tp1/n.As a result, shown in Fig. 5 (b), become the 1/n of the cycle T p1 of back electromotive force detection signal BEMF_EDGE from the cycle T p2 of the pulse signal PULSE of pulse signal generative circuit 42 output.

At moment t0, when certain back electromotive force detection signal BEMF_EDGE became high level, the counter 60 of Fig. 3 began the pulse signal PULSE from pulse signal generative circuit 42 is counted.At moment t1, when counter 60 had been counted m pulse signal PULSE, the unlatching of output high level was along signal OPEN_EDGE.

Window signal efferent 62 open from moment t1 become high level becomes high level to back electromotive force detection signal BEMF_EDGE next time moment t2 along signal OPEN_EDGE till during in, making window signal WINDOW is high level.

Like this; In the motor-drive circuit 100 of this execution mode; Before the detection of carrying out zero cross point; Be created on from the cycle T p1 of the back electromotive force detection signal BEMF_EDGE of counter electromotive force detection circuit 20 output multiply by predetermined coefficient (1-m/n) during in become the window signal WINDOW of high level, and with this window signal WINDOW become high level during be set at Tp3 during the non-driving that zero cross point detects usefulness.As a result, can set Tp3 during the non-driving adaptively according to rotating speed of motor.And then, under the situation during having fixed non-driving as in the past, need preestablish long non-driving time; But through this execution mode; Need not to surpass requiredly and set more longways,, can reduce the noise that sends from motor so can make the drive current of motor level and smooth.

And then; Window generative circuit 40 exported from certain back electromotive force detection signal BEMF_EDGE, multiply by through the cycle T p1 of back electromotive force detection signal BEMF_EDGE coefficient (1-m/n) during (behind the Tp2 * m); Make window signal WINDOW become high level; Be triggering to have exported next back electromotive force detection signal BEMF_EDGE from counter electromotive force detection circuit 20 afterwards, make window signal WINDOW become low level.As a result, can be before the detection of carrying out zero cross point, setting makes switching circuit 10u become the timing of high-impedance state reliably.

In addition, in execution mode, the number m that in timing setting portion 44, makes the pulse signal PULSE that will count is a scalable.As a result, can realize stable motor-driven according to the length of Tp3 during the non-drivings of change such as kind of the motor of driven object.

In addition, in execution mode, in pulse signal generative circuit 42, make the integer K scalable.As a result, when integer K being set hour, the gain of feedback loop improves, so can set the tracking property to the rotating speed of motor change than the highland, conversely, when integer K being set big, the gain of feedback loop descends, so can improve the stability of ring.Therefore, through set the value of K according to kind, rotating speed, the type of drive of motor, can realize best motor-driven.

Next the examples of applications of the motor-drive circuit 100 of this execution mode is described.Fig. 6 is the block diagram of structure of the dish device 200 of expression motor-drive circuit 100 that Fig. 1 has been installed.Dish device 200 be to CDs such as CD, DVD write down, the unit of reproduction processes, be installed in the electronic equipments such as CD Player, DVD player, personal computer.Dish device 200 comprises pick-up 210, signal processing part 212, dish 214, motor 110, motor-drive circuit 100.

210 pairs of dishes of pick-up, 214 irradiating lasers write desirable data, and the light that perhaps reflects through reading in is read the data that are written in the dish 214.212 pairs of data by pick-up 210 read-writes of signal processing part are carried out necessary signal processing such as processing and amplifying, A/D conversion or D/A conversion.Motor 110 is the spindle motors for dish 214 rotations are established.The dish device 200 of that kind shown in Figure 6 especially is asked to miniaturization, so as motor 110, adopt the non-sensor type do not use Hall element etc.The motor-drive circuit 100 of this execution mode can be applicable to the purposes of the spindle motor that stably drives so no transducer well.

(the 2nd execution mode)

Fig. 8 is the block diagram of structure of the motor-drive circuit 100a of expression the 2nd execution mode.Motor-drive circuit 100a provides drive current to non sensor brushless DC motor (hereinafter to be referred as " motor 110 "), controls its rotation.In this execution mode, be the three-phase DC motor of the coil Lu that comprises U phase, V phase, W phase, Lv, Lw as the motor 110 of driven object.

Motor-drive circuit 100a comprises switching circuit 10u, 10v, 10w, counter electromotive force detection circuit 20a, ON-OFF control circuit 30a, window generative circuit 40a, the pulse width modulating signal generative circuit 90 that is collectively referred to as switching circuit 10.Motor-drive circuit 100a is used as function IC and integrates on a Semiconductor substrate.For example motor-drive circuit 100a carries out PWM (PulseWidth Modulation: pulse width modulation) drive, make to obtain desirable torque to polyphase machine 110.And the change in duty cycle so that 180 degree step modes drive PWM makes the electric current that flows through each phase coil become arch bridge shape or sinusoidal wave shape.

The back electromotive force that is produced in counter electromotive force detection circuit 20a at least one coil with motor 110 is compared with the mid-point voltage of coil, detects zero cross point, output back electromotive force detection signal BEMF_EDGE.In this execution mode, counter electromotive force detection circuit 20a keeps watch on back electromotive force Vu and the mid-point voltage Vcom that is produced among the U phase coil Lu, generates back electromotive force detection signal BEMF_EDGE.The back electromotive force detection signal BEMF_EDGE that is generated is outputed to ON-OFF control circuit 30a and window generative circuit 40a.The details of counter electromotive force detection circuit 20a is explained in the back.

Pulse width modulating signal generative circuit 90 generates the pulse width modulating signal (to call pwm signal Spwm in the following text) of change in duty cycle at least according to the target torque of motor 110.The level of the periodic signal Sosc that pulse width modulating signal generative circuit 90 is wavy with triangular wave or sawtooth and the signal Strq of command torque compares, according to its magnitude relationship make pwm signal Spwm high level and low level during change.In addition, pulse width modulating signal generative circuit 90 can be made up of any of analog circuit, digital circuit.

Pulse width modulating signal generative circuit 90 also can be synthetic with the control waveform of target torque and sinusoidal wave shape or arch bridge shape for the coil current that flows through among coil Lu, Lv, the Lw is gently changed, and generates pwm signal Spwm.

ON-OFF control circuit 30a receives from the pwm signal Spwm of pulse width modulating signal generative circuit 90 with from the back electromotive force detection signal BEMF_EDGE of counter electromotive force detection circuit 20a.ON-OFF control circuit 30a controls the order of the conducting cut-off state of a plurality of switching circuit 10u, 10v, 10w based on back electromotive force detection signal BEMF_EDGE.And then ON-OFF control circuit 30a is based on pwm signal Spwm, and at least one of high-side switch that a plurality of switching circuit 10u, 10v, 10w are comprised and low side switch carries out switch control.

ON-OFF control circuit 30a comprises driving timing generative circuit 32a, drive signal combiner circuit 34a.Driving timing generative circuit 32a is transfused to back electromotive force detection signal BEMF_EDGE.Driving timing generative circuit 32a generates the drive signal DRV in 1/6 cycle of the cycle T p1 with back electromotive force detection signal BEMF_EDGE.

Drive signal combiner circuit 34a is synthetic with drive signal DRV and pwm signal Spwm, output drive signal DRV_H (u, v, w), DRV_L (u, v, w), the state of control switch circuit 10u, 10v, 10w.

Window generative circuit 40a carries out before zero cross point detects at counter electromotive force detection circuit 20a, generates the window signal WINDOW that the switch motion that is used to make the switching circuit 10u that is connected with the coil Lu that becomes the back electromotive force detected object stops, being set at high resistant.In this execution mode, predetermined level is a high level.When carrying out under 120 situation such as degree energisings etc., if become the coil Lu existence of back electromotive force detected object do not flow through electric current during, then can omit window generative circuit 40a.

Window signal WINDOW is outputed to the drive signal combiner circuit 34a of ON-OFF control circuit 30a.Drive signal combiner circuit 34a window signal WINDOW be high level during, the switch motion of the switching circuit 10u that stops to be connected with the terminal that is produced as the back electromotive force Vu that detects zero cross point and should keep watch on is set at high-impedance state.That is, be to detect zero cross point, window signal WINDOW be high level during deliberately be set at the phase of not carrying out driving.In this execution mode, among the Tp3, U is set to the phase of not carrying out driving mutually during non-driving.

Next, specify counter electromotive force detection circuit 20a.The counter electromotive force detection circuit 20a of this execution mode also is transfused to the pwm signal Spwm from pulse width modulating signal generative circuit 90 except that being transfused to back electromotive force Vu, mid-point voltage Vcom.Counter electromotive force detection circuit 20a sets the detection timing of zero cross point based on pwm signal Spwm.Counter electromotive force detection circuit 20a in the detection that sets regularly when the comparative result of back electromotive force Vu and mid-point voltage Vcom satisfies predetermined condition, exports the back electromotive force detection signal BEMF_EDGE that becomes high level.

Counter electromotive force detection circuit 20a detects regularly based on the timing setting of the level transitions of pwm signal Spwm.As detecting establishing method regularly, with pwm signal Spwm just along or negative edge be set at detect method regularly, just make along or the negative edge delay scheduled time to set the method regularly that detects etc. be effective.

In this execution mode, counter electromotive force detection circuit 20a with the level of pwm signal Spwm from the corresponding level of the conducting of the switch that comprised with a plurality of switching circuit 10u, 10v, 10w to timing by corresponding level transitions, be set at and detect timing.For example, when the low level of pwm signal Spwm corresponding to switch by, high level during corresponding to the conducting of switch, the negative edge of pwm signal Spwm is set at detects regularly.Counter electromotive force detection circuit 20a in the detection of setting so regularly, when satisfying Vu>the back electromotive force detection signal BEMF_EDGE of output high level during the condition of Vcom.

Fig. 9 is the circuit diagram of the structure example of expression counter electromotive force detection circuit 20a.Counter electromotive force detection circuit 20a comprises comparator 22, comparison value efferent 24.Counter electromotive force detection circuit 20a compares phase voltage Vu and the mid-point voltage Vcom of U phase coil Lu, and output is at Vu>become the comparison signal Scmp of high level during Vcom.

The comparison signal Scmp that comparison value efferent 24 receives as the output of comparator 22, the value during with the detection timing is exported as back electromotive force detection signal BEMF_EDGE.Comparison value efferent 24 can constitute with the latch cicuit according to the output signal of the negative edge latched comparator 22 of pwm signal Spwm.Input terminal D as the D latch cicuit of comparison value efferent 24 is transfused to comparison signal Scmp.

Negative edge testing circuit 26 detects the negative edge of pwm signal Spwm, and output becomes the negative edge signal NEDGE of high level at every turn when detecting negative edge.Negative edge signal NEDGE is imported into the clock terminal of comparison value efferent 24.

The as above action of such motor-drive circuit 100a that constitutes of explanation below.(a) of Figure 10～(1) is the sequential chart of action of the motor-drive circuit 100a of expression execution mode.The longitudinal axis of (a) of this figure～(1) and transverse axis are suitably amplified, have been dwindled for understanding conveniently, and each waveform shown in it is also for understanding convenient being simplified.(a)～(c) of this figure is respectively according to switching circuit 10u, 10v, 10w, the waveform of the driving condition of the coil Lu of expression U phase, V phase, W phase, Lv, Lw.The back electromotive force detection signal BEMF_EDGE that (d) expression of this figure is detected by counter electromotive force detection circuit 20a; The drive signal DRV that (e) expression of this figure is generated by driving timing generative circuit 32a, the window signal WINDOW that (f) expression of this figure is generated by window generative circuit 40a.And then, the high-side switch of (g) of this figure～(1) expression switching circuit 10u～10w and drive signal DRV_H, the DRV_L of low side switch.

Shown in Figure 10 (a)～(c), in this execution mode, drive and make drive current become the arch bridge waveform.Certainly, the invention is not restricted to this, also can be sinusoidal wave as stated.In this execution mode, back electromotive force detection signal BEMF_EDGE is shown in this figure (d), and each zero cross point that intersects at back electromotive force Vu and mid-point voltage Vcom is generated.Driving timing generative circuit 32a generates the drive signal DRV shown in (e) that the cycle make back electromotive force detection signal BEMF_EDGE becomes this figure after 1/6 times.The drive signal DRV back electromotive force detection signal BEMF_EDGE that also can give as shown in the figure postpones Td.Prolong Td through regulating this, motor-driven is optimised.

The drive signal DRV that drive signal combiner circuit 34a is generated based on driving timing generative circuit 32a generates and to be used for the conducting of control switch circuit 10u～10w and the drive signal DRV_H that ends (U, V, W), DRV_L (U, V, W).This driving sequence is according to suitably settings such as energising angles.

The high level of drive signal DRV_HU shown in Figure 10 (g) is corresponding to the conducting state of the high-side switch of switching circuit 10u, and low level is corresponding to cut-off state.Drive signal DRV_H shown in (f) of this figure～(1) (V, W), DRV_L (U, V, W) also are the same.And then; The conducting state of at least one of high-side switch or low side switch is by pulse width modulation; Obtain the drive waveforms shown in (a)～(c) of this figure, the high-side switch of switching circuit 10u～10w or low side switch are with higher frequency alternate repetition conducting and end.

When drive signal combiner circuit 34a is exported at each back electromotive force detection signal BEMF_EDGE, change the drive signal DRV_H of switching circuit 10u～10w, the conducting cut-off state of DRV_L according to predetermined driving sequence.

Window signal WINDOW shown in this figure (f) was become high level by window generative circuit 40a before the moment that zero cross point takes place.Drive signal combiner circuit 34a window generative circuit 40a be high level during, make the drive signal DRV_HU, the DRV_LU that output to switching circuit 10u become low level, high-side switch and low side switch are ended, become high-impedance state.Among (g) of this figure, (j) with oblique line be expressed as detect zero cross point and be set to high-impedance state during.When an end that becomes high level, coil Lu as window signal WINDOW is set to high-impedance state, can carry out the detection of zero cross point, back electromotive force detection signal BEMF_EDGE is generated.

(a)～(e) of Figure 11 is the oscillogram of situation of detection of zero cross point of the motor-drive circuit 100a of expression execution mode.(a) expression pwm signal Spwm of Figure 11, (b) expression phase voltage Vu and the mid-point voltage Vcom of this figure, (c) expression comparison signal Scmp of this figure, (d) expression negative edge signal NEDGE of this figure, (e) expression back electromotive force detection signal BEMF_EDGE of this figure.

Pwm signal Spwm with torque corresponding duty ratio alternate repetition high level and low level.Be set among the phase voltage Vu of U phase of non-driven state,, produce the back electromotive force of pulse type corresponding to based on other phase coils Lv of pwm signal Spwm, the switch control of Lw.Shown in this figure (b), phase voltage Vu occurs back electromotive force during for high level at pwm signal Spwm, near the voltage PWM signal Spwm becomes 0V during for low level.Here, there are caused delays such as transmission time in the variation of the transformation of the signal of pwm signal Spwm and phase voltage Vu because of signal.Therefore, the phase voltage Vu generation that is later than the negative edge of pwm signal Spwm periodically drops near the 0V.In addition, the mid-point voltage Vcom shown in this figure (b) is actually alternate repetition and presents illustrated voltage level and low level signal, but representes with straight line because of simplification here.

Phase voltage Vu shown in this figure (b) becomes the timing that high level, other phase coils Lv, Lw are applied in pulse voltage at pwm signal Spwm, noise component(s) occurs.Because this noise component(s), relatively phase voltage Vu and mid-point voltage Vcom and the comparison signal Scmp that obtains high level and low level occur repeatedly shown in this figure (c).This comparison signal Scmp is regularly latched along the detection of signal NEDGE in appearance of negative, is exported as the back electromotive force detection signal BEMF_EDGE shown in this figure (e).It is more stable signal that the back electromotive force detection signal BEMF_EDGE that generates like this compares with the back electromotive force detection signal BEMF_EDGE shown in (c) of Fig. 7.

In the motor-drive circuit 100a of this execution mode, with become to back electromotive force Vu bring noise component(s) main cause pwm signal Spwm synchronously, the detection of setting zero cross point regularly.Its result can regularly suitably be set at the less moment of noise effect with the detection of zero cross point, can prevent the erroneous detection of zero cross point.

In addition; Shown in Figure 11 (c), after making the switch conduction that coil connected different, almost become maximum owing to pulse modulation and at the noise component(s) that produces in the back electromotive force with the coil of the appearance back electromotive force that becomes detected object; Decay gradually then, such situation is in the majority.In this execution mode; Since counter electromotive force detection circuit 20a with the level of pwm signal Spwm from the corresponding level of conducting of the switch that comprised with a plurality of switching circuit 10u, 10v, 10w to timing by corresponding level transitions; Be set at and detect regularly, so can under the less state of noise component(s), carry out the detection of zero cross point.

Next the examples of applications of the motor-drive circuit 100a of this execution mode is described.Fig. 6 is the block diagram of structure of the dish device 200 of expression motor-drive circuit 100a that Fig. 8 has been installed.Dish device 200 be to CDs such as CD, DVD write down, the unit of reproduction processes, be installed in the electronic equipments such as CD Player, DVD player, personal computer.Dish device 200 comprises pick-up 210, signal processing part 212, dish 214, motor 110, motor-drive circuit 100a.

210 pairs of dishes of pick-up, 214 irradiating lasers write desirable data, and the light that perhaps reflects through reading in is read the data that are written in the dish 214.212 pairs of data by pick-up 210 read-writes of signal processing part are carried out necessary signal processing such as processing and amplifying, A/D conversion or D/A conversion.Motor 110 is the spindle motors for dish 214 rotations are established.The dish device 200 of that kind shown in Figure 6 especially is asked to miniaturization, so as motor 110, adopt the non-sensor type do not use Hall element etc.The motor-drive circuit 100a of this execution mode can be applicable to the purposes of the spindle motor that stably drives so no transducer well.

(the 3rd execution mode)

Figure 12 is the block diagram of structure of the motor-drive circuit 100b of expression the 3rd execution mode.Motor-drive circuit 100b provides drive current to non sensor brushless DC motor (hereinafter to be referred as " motor 110 "), controls its rotation.In this execution mode, be the three-phase DC motor of the coil Lu that comprises U phase, V phase, W phase, Lv, Lw as the motor 110 of driven object.

Motor-drive circuit 100b comprises switching circuit 10u, 10v, 10w, counter electromotive force detection circuit 20b, ON-OFF control circuit 30b, window signal generative circuit 40b, pulse signal generative circuit 42b, sine wave signal generative circuit 70, the pwm signal generative circuit 80 that is collectively referred to as switching circuit 10.Motor-drive circuit 100b is used as function IC and integrates on a Semiconductor substrate.For example motor-drive circuit 100b carries out PWM (Pulse Width Modulation: pulse width modulation) drive, make the electric current that flows through each phase coil become arch bridge shape or sinusoidal wave shape with 180 degree step modes.

Switching circuit 10u, 10v, 10w are respectively by the coil Lu of motor 110, Lv, Lw and establish.Switching circuit 10u, 10v, 10w for example comprise the high-side switch and the low side switch ground that are connected in series between supply voltage and the earthing potential and constitute, and the tie point of two switches links to each other with coil.The control terminal of high-side switch and low side switch is transfused to drive signal DRV_H (U, V, W) and drive signal DRV_L (U, V, W) respectively.Switching circuit 10u, 10v, 10w are the voltage that under the state of conducting an end of the coil that connected is applied high level at high-side switch, at low side switch are to apply low level voltage under the state of conducting.In addition, end simultaneously, be set to high-impedance state through high-side switch and low side switch.

The back electromotive force that is produced in counter electromotive force detection circuit 20b at least one coil with motor 110 is compared with the mid-point voltage of coil, detects zero cross point, output back electromotive force detection signal BEMF_EDGE.Counter electromotive force detection circuit 20b is configured with normally comprising comparator.In this execution mode, counter electromotive force detection circuit 20b keeps watch on the back electromotive force Vu that produces among the U phase coil Lu (below be also referred to as phase voltage Vu) and mid-point voltage Vcom, exports at Vu>become the back electromotive force detection signal BEMF_EDGE of high level during Vcom.The back electromotive force detection signal BEMF_EDGE that is generated is outputed to ON-OFF control circuit 30b, window signal generative circuit 40b, pulse signal generative circuit 42b.

The back electromotive force detection signal BEMF_EDGE that pulse signal generative circuit 42b reception is exported from counter electromotive force detection circuit 20b generates and this back electromotive force detection signal BEMF_EDGE is synchronous and frequency is the pulse signal PULSE of n times (n is the integer more than 2).Pulse signal PULSE is outputed to sine wave signal generative circuit 70 and window signal generative circuit 40b.

The pulse signal PULSE that sine wave signal generative circuit 70 receives from pulse signal generative circuit 42b is according to the control signal CNT of this pulse signal PULSE sine wave output shape.Pwm signal generative circuit 80 will be synthetic from the dtc signal Strq of the target torque of the control signal CNT of sine wave signal generative circuit 70 and indication motor 110, the pulse width modulating signal (to call pwm signal Spwm in the following text) that has generated by pulse width modulation.

ON-OFF control circuit 30b reception is from the back electromotive force detection signal BEMF_EDGE of counter electromotive force detection circuit 20b output and the pwm signal Spwm that exports from pwm signal generative circuit 80.ON-OFF control circuit 30b controls the order of the conducting cut-off state of a plurality of switching circuit 10u, 10v, 10w based on back electromotive force detection signal BEMF_EDGE, regulates the electric current of the coil Lu flow through motor 110, Lv, Lw.In addition, ON-OFF control circuit 30b is based on pwm signal Spwm, and at least one of high-side switch that a plurality of switching circuit 10u, 10v, 10w are comprised and low side switch carries out switch control.ON-OFF control circuit 30b comprises driving timing generative circuit 32b and drive signal combiner circuit 34b.

Driving timing generative circuit 32b is transfused to back electromotive force detection signal BEMF_EDGE.Driving timing generative circuit 32b generates the drive signal DRV in 1/6 cycle of the cycle T p1 with back electromotive force detection signal BEMF_EDGE.

Drive signal combiner circuit 34b with synthetic from the pwm signal Spwm of pwm signal generative circuit 80 outputs, outputs to switching circuit 10u, 10v, 10w with drive signal DRV.

Window signal generative circuit 40b is before counter electromotive force detection circuit 20b carries out the zero cross point detection, and output becomes the window signal WINDOW of high level.Window signal generative circuit 40b is transfused to from the back electromotive force detection signal BEMF_EDGE of counter electromotive force detection circuit 20b with from the pulse signal PULSE of pulse signal generative circuit 42b.Window signal generative circuit 40b output after detecting certain back electromotive force detection signal BEMF_EDGE, detected m (m be satisfy m the integer of n) become high level during pulse signal PULSE, when detecting next back electromotive force detection signal BEMF_EDGE, become low level window signal WINDOW afterwards.

Preferred integer m is adjustable.For example motor-drive circuit 100b can have the register that is used to preserve integer m, and being constituted as can be from external setting-up integer m.

ON-OFF control circuit 30b receives the window signal WINDOW from window signal generative circuit 40b.ON-OFF control circuit 30b window signal WINDOW be high level during, the switch motion of the switching circuit 10u that stops to be connected with the coil Lu that is kept watch on back electromotive force by counter electromotive force detection circuit 20b is set at high-impedance state.That is, be to detect zero cross point, window signal WINDOW be high level during be set to the phase that does not deliberately drive.In this execution mode, among the Tp3, U is set to the phase of not carrying out driving mutually during non-driving.

Figure 13 is the circuit diagram of the structure of expression sine wave signal generative circuit 70 and pwm signal generative circuit 80.Sine wave signal generative circuit 70 comprises sinusoidal pattern (pattern) memory 72.Preserve sinuous control signal CNT with the form of digital value in the sinusoidal pattern memory 72.Sine wave signal generative circuit 70 is read sinuous control signal CNT successively according to pulse signal PULSE and is exported.In addition, sine wave signal generative circuit 70 also can be preserved control signal CNT with the form of the analogue value.

Pwm signal generative circuit 80 comprises synthetic portion 82 and pulse-width modulator 84.Synthetic portion 82 will multiply each other from the control signal CNT of sine wave signal generative circuit 70 outputs and dtc signal Strq from the outside and synthesize.Multiplied result is used as composite signal Scmb and outputs to pulse-width modulator 84 from synthetic portion 82.Pulse-width modulator 84 will compare with predetermined periodic signal Sosc from the composite signal Scmb of synthetic portion 82, generates pwm signal Spwm.Periodic signal Sosc is the cyclical signal of signal level by triangular wave or the wavy variation of sawtooth.The pulse duration of the pwm signal Spwm that generates like this changes corresponding to the magnitude relationship of composite signal Scmb and periodic signal Sosc.

Figure 14 is the block diagram of the structure of indicating impulse signal generating circuit 42b.Pulse signal generative circuit 42b has frequency counter 50b, clock signal generating circuit 56b.

Frequency counter 50b measure back electromotive force detection signal BEMF_EDGE frequency, be cycle T p1.For example frequency counter 50b is transfused to the clock signal (not shown) of preset frequency.Frequency counter 50b to from be transfused to certain back electromotive force detection signal BEMF_EDGE to be transfused to next back electromotive force detection signal BEMF_EDGE during in the clock signal that is transfused to count, measure the cycle T p1 of back electromotive force detection signal BEMF_EDGE.Frequency counter 50b exports measured count value COUNT as frequency values successively.

Clock signal generating circuit 56b generates the pulse signal PULSE of n times of (n is the integer more than 2) frequency of the frequency of being measured by frequency counter 50b.That is, the cycle T p2 of pulse signal PULSE is set to the 1/n of the cycle T p1 of back electromotive force detection signal BEMF_EDGE.

Clock signal generating circuit 56b carries out computing to the frequency values COUNT in past K time (K is the integer more than 1) of being measured by frequency counter 50b, according to the result of computing, and the frequency of the pulse signal that setting should generate.Preferably corresponding with the number of the frequency values that becomes operand integer K is adjustable.

For realizing this function, pulse signal generative circuit 42b has storage part 52b and operational part 54b in the prime of clock signal generating circuit 56b.Storage part 52b preserves the frequency values COUNT of L time (L is the integer that satisfies L >=K) in the past.Storage part 52b for example can be a L level shift register.Operational part 54b carries out predetermined computing based on the frequency values that is kept among the storage part 52b.Calculation process can be simple average calculating operation, also can be the weighted average computing.

The pulse signal PULSE of the operation result correspondent frequency of clock signal generating circuit 56b generation and operational part 54b.For example, operational part 54b carries out computing, the frequency of decision pulse signal PULSE to the frequency values that is kept in L time the frequency values among the storage part 52b up-to-date K time.Calculation process can be that K count value carried out simple average calculating operation, also can carry out the weighted average computing.Integer K is preferably variable as stated, and being constituted as can be from external setting-up.During K=1, according to the cycle T p1 of previous back electromotive force detection signal BEMF_EDGE, the cycle T p2 of setting pulse signal PULSE.

Figure 15 is the circuit diagram of the structure of expression window signal generative circuit 40b.Window signal generative circuit 40b comprises counter 60b, window signal efferent 62b, is transfused to from the back electromotive force detection signal BEMF_EDGE of counter electromotive force detection circuit 20b output and the pulse signal PULSE that exports from pulse signal generative circuit 42b.

Counter 60b is after detecting certain back electromotive force detection signal BEMF_EDGE, and the unlatching that output becomes high level when having counted m pulse signal PULSE is along signal OPEN_EDGE.Window signal efferent 62b output is becoming high level during along signal OPEN_EDGE, when detecting next back electromotive force detection signal BEMF_EDGE, is becoming low level window signal WINDOW afterwards from the unlatching of counter 60b output high level.

The as above action of the motor-drive circuit 100b of formation like this of explanation below.(a) of Figure 16～(1) is the sequential chart of action of the motor-drive circuit 100b of expression execution mode.The longitudinal axis of (a) of this figure～(1) and transverse axis are suitably amplified, have been dwindled for understanding conveniently, and each waveform shown in it is also for understanding convenient being simplified.(a)～(c) of this figure is respectively according to switching circuit 10u, 10v, 10w, the waveform of the driving condition of the coil Lu of expression U phase, V phase, W phase, Lv, Lw.The back electromotive force detection signal BEMF_EDGE that (d) expression of this figure is detected by counter electromotive force detection circuit 20b; The drive signal DRV that (e) expression of this figure is generated by driving timing generative circuit 32b, the window signal WINDOW that (f) expression of this figure is generated by window signal generative circuit 40b.And then, the high-side switch of (g) of this figure～(1) expression switching circuit 10u～10w and drive signal DRV_H, the DRV_L of low side switch.

Shown in Figure 16 (a)～(c), in this execution mode, utilize sinuous control signal CNT to drive, make drive current become to squint each other the sine wave of 120 degree.Certainly, the invention is not restricted to this, also can be to utilize control signal CNT to drive, and makes drive current become the waveform of arch bridge shape.In this execution mode, back electromotive force detection signal BEMF_EDGE is shown in this figure (d), and each zero cross point that intersects at back electromotive force Vu and mid-point voltage Vcom is generated.

Driving timing generative circuit 32b generates the drive signal DRV shown in (e) that the cycle T p1 make back electromotive force detection signal BEMF_EDGE becomes this figure after 1/6 times.In addition, pulse signal generative circuit 42b is synchronized with the pulse signal PULSE after back electromotive force detection signal BEMF_EDGE ground generates frequency multiplication.Sine wave signal generative circuit 70 generates sinuous control signal CNT according to pulse signal PULSE.Therefore, shown in this figure (a)～(c), the electric current that is flow through among each coil Lu, Lv, the Lw is synchronized to the control of back electromotive force detection signal BEMF_EDGE ground.

In addition, the drive signal DRV back electromotive force detection signal BEMF_EDGE that also can give as shown in the figure prolongs Td.Should postpone Td through regulating, motor-driven is optimised.In this case, the back level that needs only at counter electromotive force detection circuit 20b is provided with delay circuit.

The drive signal DRV that drive signal combiner circuit 34b is generated based on driving timing generative circuit 32b generates and to be used for the conducting of control switch circuit 10u～10w and the drive signal DRV_H that ends (U, V, W), DRV_L (U, V, W).This driving sequence is according to suitably settings such as energising angles.

The high level of drive signal DRV_HU shown in Figure 16 (g) is corresponding to the conducting state of the high-side switch of switching circuit 10u, and low level is corresponding to cut-off state.Drive signal DRV_H shown in (g) of this figure～(1) (V, W), DRV_L (U, V, W) also are the same.And then, based at least one conducting state of pwm signal Spwm control high-side switch or low side switch, obtain the drive waveforms shown in (a)～(c) of this figure.

Window signal WINDOW shown in this figure (f) was become high level by window signal generative circuit 40b before the moment that zero cross point takes place.Drive signal combiner circuit 34b window signal generative circuit 40b be high level during, make the drive signal DRV_HU, the DRV_LU that output to switching circuit 10u become low level, high-side switch and low side switch are ended, become high-impedance state.Among (g) of this figure, (j) with oblique line be expressed as detect zero cross point and be set to high-impedance state during.When an end that becomes high level, coil Lu as window signal WINDOW is set to high-impedance state, can carry out the detection of zero cross point, back electromotive force detection signal BEMF_EDGE is generated.When back electromotive force detection signal BEMF_EDGE became high level, window signal generative circuit 40b made window signal WINDOW become low level.Shown in this figure (a), when switching circuit 10 was set to high resistant, it is discontinuous that coil current becomes.

(a)～(e) of Figure 17 is the sequential chart that expression generates the appearance of window signal WINDOW and sinuous control signal CNT.(a) expression back electromotive force detection signal BEMF_EDGE of this figure; The pulse signal PULSE that (b) indicating impulse signal generating circuit 42b of this figure is generated; The unlatching that (c) expression counter 60b of this figure is generated is along signal OPEN_EDGE; (d) expression window signal WINDOW of this figure, the control signal CNT that (e) expression sine wave signal generative circuit 70 of this figure is generated.

When back electromotive force detection signal BEMF_EDGE became high level, the frequency counter 50b of Figure 14 began counting, and the count value COUNT that counts up to till the moment that back electromotive force detection signal BEMF_EDGE next time becomes high level is outputed to storage part 52b.1 time count value COUNT is pass by in storage at least among the storage part 52b.If the cycle of the employed clock of counting of frequency counter 50b is Tck, then the cycle T p1 of back electromotive force detection signal BEMF_EDGE becomes Tck * COUNT.Operational part 54b uses K time count value in the past to determine the cycle T p2 of pulse signal PULSE, makes Tp2=Tp1/n.As a result, shown in Figure 16 (b), become the 1/n of the cycle T p1 of back electromotive force detection signal BEMF_EDGE from the cycle T p2 of the pulse signal PULSE of pulse signal generative circuit 42b output.

At moment t0, when certain back electromotive force detection signal BEMF_EDGE became high level, the counter 60b of Figure 15 began the pulse signal PULSE from pulse signal generative circuit 42b is counted.At moment t1, when counter 60b had counted m pulse signal PULSE, the unlatching of such output high level was along signal OPEN_EDGE shown in Figure 17 (c).

Window signal efferent 62b open from moment t1 become high level becomes high level to back electromotive force detection signal BEMF_EDGE next time moment t2 along signal OPEN_EDGE till during in, make window signal WINDOW become high level.

In addition, shown in Figure 17 (e), sine wave signal generative circuit 70 is according to the control signal CNT of pulse signal PULSE sine wave output shape.The control signal CNT that generates like this by pulse width modulation, offers coil Lu, Lv, Lw via switching circuit 10u, 10v, 10w in pwm signal generative circuit 80.

Like this, in the motor-drive circuit 100b of this execution mode, generate and the synchronous pulse signal PULSE of back electromotive force detection signal BEMF_EDGE, and control the power that offers coil Lu, Lv, Lw based on this pulse signal PULSE.Because sine wave signal generative circuit 70 generates sinuous control signal CNT according to pulse signal PULSE, so the frequency of control signal CNT is directly proportional with rotating speed of motor.As a result, can come sinuous power to be provided,, can make motor 110 stably with desirable torque rotation so can realize stable sine wave drive according to the position of the rotor of motor 110 to coil.

Like this; In the motor-drive circuit 100b of this execution mode; Before the detection of carrying out zero cross point; Be created on from the cycle T p1 of the back electromotive force detection signal BEMF_EDGE of counter electromotive force detection circuit 20b output multiply by predetermined coefficient (1-m/n) during in become the window signal WINDOW of high level, and with this window signal WINDOW become high level during be set at Tp3 during the non-driving that zero cross point detects usefulness.As a result, can set Tp3 during the non-driving adaptively according to rotating speed of motor.And then, under the situation during having fixed non-driving as in the past, need preestablish long non-driving time; But through this execution mode; Need not to surpass requiredly and set more longways,, can reduce the noise that sends from motor so can make the drive current of motor level and smooth.

In this execution mode, window signal WINDOW becomes the signal identical with the pulse signal PULSE of the generation that is used for control signal CNT.Therefore, it is unified mutually to make timing that window signal WINDOW becomes high level and the level of sinuous control signal CNT become 0 timing, so can detect zero cross point more exactly.

And then; Window signal generative circuit 40b exported from certain back electromotive force detection signal BEMF_EDGE, multiply by through the cycle T p1 of back electromotive force detection signal BEMF_EDGE coefficient (1-m/n) during (behind the Tp2 * m); Make window signal WINDOW become high level; Then, be triggering to have exported next back electromotive force detection signal BEMF_EDGE from counter electromotive force detection circuit 20b, make window signal WINDOW become low level.As a result, can be before the detection of carrying out zero cross point, setting makes switching circuit 10u become the timing of high-impedance state reliably.

And then, in execution mode, make it possible in window signal generative circuit 40b to regulate the number m of the pulse signal PULSE that will count.Its result can realize stable motor-driven according to the length of Tp3 during the non-drivings of change such as kind of the motor of driven object.

And, in execution mode, make it possible in pulse signal generative circuit 42b, regulate integer K.Its result is setting integer K hour, and the gain of feedback loop improves; So can set the tracking property that changes to rotating speed of motor higher, conversely, when K being set big; Because the gain of feedback loop descends, so can improve the stability of ring.Therefore, through set the value of K according to kind, rotating speed, the type of drive of motor, can realize best motor-driven.

Next the examples of applications of the motor-drive circuit 100b of this execution mode is described.Fig. 6 is the block diagram of structure of the dish device 200 of expression motor-drive circuit 100b that Figure 12 has been installed.Dish device 200 be to CDs such as CD, DVD write down, the unit of reproduction processes, be installed in the electronic equipments such as CD Player, DVD player, personal computer.Dish device 200 comprises pick-up 210, signal processing part 212, dish 214, motor 110, motor-drive circuit 100b.

210 pairs of dishes of pick-up, 214 irradiating lasers write desirable data, and the light that perhaps reflects through reading in is read the data that are written in the dish 214.212 pairs of data by pick-up 210 read-writes of signal processing part are carried out necessary signal processing such as processing and amplifying, A/D conversion or D/A conversion.Motor 110 is the spindle motors for dish 214 rotations are established.The dish device 200 of that kind shown in Figure 6 especially is asked to miniaturization, so as motor 110, adopt the non-sensor type do not use Hall element etc.The motor-drive circuit 100b of this execution mode can be applicable to the purposes of the spindle motor that stably drives so no transducer well.

More than based on execution mode the present invention has been described.This execution mode is an illustration, and those skilled in the art can understand and can carry out various distortion to the combination of its each structure important document and variety of processes, and these variation are also contained in the scope of the present invention.

The situation that drives three phase electric machine has been described, but the present invention can also be applicable to the driving of the electric machine without sensor beyond the three-phase well in the 1st execution mode.It for example can be five-phase induction motor.In addition, explained that in the 1st execution mode back electromotive force Vu and the mid-point voltage Vcom with the U phase compares the situation that detects zero cross point, but the invention is not restricted to this.For example also can counter electromotive force detection circuit 20a be set mutually respectively, generate back electromotive force detection signal BEMF_EDGE U phase, V phase, W.

In addition; In the 1st execution mode; Being to become Vu through in the process that phase voltage Vu rises, detecting>state of Vcom detects zero cross point; But the invention is not restricted to this, also can be to detect in the process that phase voltage Vu descends through counter electromotive force detection circuit 20a to become Vu < state of Vcom detects zero cross point.

In the 1st execution mode, be negative edge with pwm signal Spwm be set at zero cross point detection regularly, but the invention is not restricted to this, detect regularly as long as counter electromotive force detection circuit 20a will be set at the moment that pulse-modulated signal is synchronously stipulated.For example, counter electromotive force detection circuit 20a can detect regularly being set at through the moment after the scheduled time from negative edge.At this moment, through regulating the scheduled time, can carry out the detection of suitable zero cross point.

In addition, the situation with the PWM mode drive motors of 180 degree energisings has been described in the 1st execution mode, but has been the invention is not restricted to this, can be widely used in the motor-drive circuit that adopts the pulse modulation mode.

The situation that drives three phase electric machine has been described, but the present invention can also be applicable to the driving of the electric machine without sensor beyond the three-phase well in the 2nd execution mode.It for example can be five-phase induction motor.In addition, explained that in the 2nd execution mode back electromotive force Vu and the mid-point voltage Vcom with the U phase compares the situation that detects zero cross point, but the invention is not restricted to this.For example also can counter electromotive force detection circuit 20a be set mutually respectively, generate back electromotive force detection signal BEMF_EDGE U phase, V phase, W.

In addition; In the 2nd execution mode; Being to become Vu through in the process that phase voltage Vu rises, detecting>state of Vcom detects zero cross point; But the invention is not restricted to this, also can be to detect in the process that phase voltage Vu descends through counter electromotive force detection circuit 20a to become Vu < state of Vcom detects zero cross point.

In the 2nd execution mode, be negative edge with pwm signal Spwm be set at zero cross point detection regularly, but the invention is not restricted to this, detect regularly as long as counter electromotive force detection circuit 20a will be set at the moment that pulse-modulated signal is synchronously stipulated.For example, counter electromotive force detection circuit 20a can detect regularly being set at through the moment after the scheduled time from negative edge.At this moment, through regulating the scheduled time, can carry out the detection of suitable zero cross point.

In addition, the situation with the PWM mode drive motors of 180 degree energisings has been described in the 2nd execution mode, but has been the invention is not restricted to this, can be widely used in the motor-drive circuit that adopts the pulse modulation mode.

The situation that drives three phase electric machine has been described, but the present invention can also be applicable to the driving of the electric machine without sensor beyond the three-phase well in the 3rd execution mode.It for example can be five-phase induction motor.In addition, in execution mode, explained the back electromotive force Vu of U phase and mid-point voltage Vcom compared and detected zero cross point, and then during non-driving, made the switching circuit 10u of U phase become the situation of high resistant, but the invention is not restricted to this.For example also can counter electromotive force detection circuit 20b be set mutually respectively, generate back electromotive force detection signal BEMF_EDGE, before the detection of each zero cross point, set during the non-driving U phase, V phase, W.In this case, through generate with back electromotive force detection signal BEMF_EDGE synchronously and the pulse signal PULSE after making it to become doubly, also can obtain effect of the present invention.

The high level of illustrated signal, the setting of low level logic only are examples in each execution mode, can consider various variation to the structure of logic circuit block, and such variation is also contained in the scope of the present invention.

Based on execution mode the present invention has been described, but obviously execution mode only is expression principle of the present invention, application, in the scope of the thought of the present invention that does not break away from claims defined, the change that can much be out of shape and dispose execution mode.

(industrial utilizability)

The present invention can be applicable to the driving of motor.

Claims

1. motor-drive circuit that provides drive current to drive to polyphase machine comprises:

When establishing above-mentioned pre-determined factor when being α; Above-mentioned window generative circuit will from above-mentioned counter electromotive force detection circuit export certain back electromotive force detection signal, through the cycle of above-mentioned back electromotive force detection signal multiply by coefficient (1-α) during after the moment; Make above-mentioned window signal be changed to above-mentioned predetermined level, wherein α is the real number that satisfies 0＜α＜1;

Above-mentioned window generative circuit comprises:

The pulse signal generative circuit receives from the above-mentioned back electromotive force detection signal of above-mentioned counter electromotive force detection circuit output, generates the pulse signal of the n overtones band of this back electromotive force detection signal, wherein n be more than 2 integer and

Timing setting portion; Reception is from the above-mentioned back electromotive force detection signal of above-mentioned counter electromotive force detection circuit with from the above-mentioned pulse signal of above-mentioned pulse signal generative circuit; After detecting certain back electromotive force detection signal, when having detected m above-mentioned pulse signal, make above-mentioned window signal become above-mentioned predetermined level, and after make above-mentioned window signal become the level that is different from above-mentioned predetermined level when detecting next back electromotive force detection signal; Wherein m is the integer that satisfies m＜n

Wherein, α=1-m/n.

2. motor-drive circuit according to claim 1 is characterized in that:

Above-mentioned timing setting portion has the adjusting device of above-mentioned integer m.

3. motor-drive circuit according to claim 1 and 2 is characterized in that:

Above-mentioned pulse signal generative circuit comprises

Frequency counter, measure above-mentioned back electromotive force detection signal frequency and

Clock signal generation portion uses K time count value in the past, the pulse signal of the n overtones band of the frequency that generation said frequencies counter is measured, and wherein K is the integer more than 1.

4. motor-drive circuit according to claim 3 is characterized in that:

Past K time the frequency values that above-mentioned clock signal generation portion is measured the said frequencies counter carries out computing, according to the result of computing, and the frequency of the pulse signal that setting should generate.

5. motor-drive circuit according to claim 4 is characterized in that:

Above-mentioned clock signal generation portion has the adjusting device of above-mentioned integer K.

6. motor-drive circuit according to claim 4 is characterized in that:

Above-mentioned pulse signal generative circuit also comprises

Storage part is preserved past L time the frequency values that frequency counter is measured, wherein L be satisfy L >=K integer and

Operational part based on the frequency values that above-mentioned storage part is preserved, is carried out above-mentioned predetermined computing;

The pulse signal of the operation result correspondent frequency of above-mentioned clock signal generation portion's generation and above-mentioned operational part.

7. motor-drive circuit according to claim 6 is characterized in that:

Above-mentioned storage part is a L level shift register.

8. motor-drive circuit according to claim 6 is characterized in that:

Up-to-date K time frequency values carries out computing in L time the frequency values that above-mentioned operational part is preserved above-mentioned storage part, decides the frequency of above-mentioned pulse signal.

9. motor-drive circuit according to claim 1 is characterized in that:

Above-mentioned timing setting portion comprises

Counter; Reception is from the back electromotive force detection signal of above-mentioned counter electromotive force detection circuit output and the pulse signal of exporting from above-mentioned pulse signal generative circuit; Output becomes predetermined level after detect certain back electromotive force detection signal, when having counted m above-mentioned pulse signal unlatching along signal and

The window signal efferent, output becomes above-mentioned predetermined level during along signal, when detecting next back electromotive force detection signal, becomes the window signal of the level that is different from above-mentioned predetermined level afterwards in the unlatching of exporting above-mentioned predetermined level from above-mentioned counter.

10. motor-drive circuit according to claim 1 and 2 is characterized in that:

Integrated on a Semiconductor substrate.

11. a dish device is characterized in that, comprising:

Make the spindle motor of disc spins; With

Drive the claim 1 or the 2 described motor-drive circuits of above-mentioned spindle motor.

12. a motor-drive circuit that provides drive current to drive to polyphase machine is characterized in that, comprising:

The pulse-modulated signal generative circuit generates the pulse-modulated signal of change in duty cycle at least according to the target torque of above-mentioned polyphase machine;

ON-OFF control circuit; Reception is from the above-mentioned pulse-modulated signal of above-mentioned pulse-modulated signal generative circuit with from the above-mentioned back electromotive force detection signal of above-mentioned counter electromotive force detection circuit; Control the order of the conducting cut-off state of above-mentioned a plurality of switching circuits based on above-mentioned back electromotive force detection signal; And, at least one of high-side switch that above-mentioned a plurality of switching circuit comprised and low side switch carried out switch control based on above-mentioned pulse-modulated signal; And, from the window signal of above-mentioned window generative circuit be above-mentioned predetermined level during stop the switch motion of said switching circuit, said switching circuit is set at high-impedance state;

Wherein, Above-mentioned counter electromotive force detection circuit detects regularly based on setting from the above-mentioned pulse-modulated signal of above-mentioned pulse-modulated signal generative circuit; And in the detection that sets regularly, the above-mentioned back electromotive force detection signal of output predetermined level when the comparative result of above-mentioned back electromotive force and above-mentioned mid-point voltage satisfies predetermined condition;

Above-mentioned window generative circuit comprises:

Wherein, α=1-m/n.

13. motor-drive circuit according to claim 12 is characterized in that:

Above-mentioned counter electromotive force detection circuit is set above-mentioned detection regularly based on the timing of the level transitions of above-mentioned pulse-modulated signal.

14. motor-drive circuit according to claim 13 is characterized in that:

Above-mentioned counter electromotive force detection circuit with the level of above-mentioned pulse-modulated signal from the corresponding level of conducting of the switch that comprised with above-mentioned a plurality of switching circuit to timing by corresponding level transitions, set above-mentioned detection for regularly.

15. each the described motor-drive circuit according to claim 12 to 14 is characterized in that:

Above-mentioned counter electromotive force detection circuit in above-mentioned detection regularly when the magnitude relationship of above-mentioned back electromotive force and above-mentioned mid-point voltage satisfies predetermined condition, is exported above-mentioned back electromotive force detection signal.

16. each the described motor-drive circuit according to claim 12 to 14 is characterized in that:

Above-mentioned counter electromotive force detection circuit comprises

Comparator, with above-mentioned back electromotive force and above-mentioned mid-point voltage compares and

The comparison value efferent receives the output signal of above-mentioned comparator, and output is in the value of above-mentioned detection regularly the time.

17. motor-drive circuit according to claim 16 is characterized in that:

Above-mentioned comparison value efferent is the latch cicuit that latchs the output signal of above-mentioned comparator according to above-mentioned pulse-modulated signal.

18. each the described motor-drive circuit according to claim 12 to 14 is characterized in that:

Integrated on a Semiconductor substrate.

19. a dish device is characterized in that, comprising:

Make the spindle motor of disc spins; With

Drive each described motor-drive circuit of the claim 12 to 14 of above-mentioned spindle motor.

20. a motor-drive circuit that provides drive current to drive to polyphase machine is characterized in that, comprising:

Counter electromotive force detection circuit, the back electromotive force that is produced at least one coil with above-mentioned polyphase machine and the mid-point voltage of coil compare, and detect zero cross point, the back electromotive force detection signal of output predetermined level;

The pulse signal generative circuit receives above-mentioned back electromotive force detection signal, generate with this back electromotive force detection signal synchronously and frequency be the n pulse signal doubly of above-mentioned back electromotive force detection signal, wherein n is the integer more than 2;

The sine wave signal generative circuit receives the above-mentioned pulse signal from above-mentioned pulse signal generative circuit, and according to the control signal of this pulse signal sine wave output shape;

The pulse-modulated signal generative circuit will be synthetic with the dtc signal of the target torque of the above-mentioned polyphase machine of indication from the above-mentioned control signal of above-mentioned sine wave signal generative circuit, generate and carry out pulse modulated pulse-modulated signal; And

ON-OFF control circuit; Reception is from the above-mentioned back electromotive force detection signal of above-mentioned counter electromotive force detection circuit with from the above-mentioned pulse-modulated signal of above-mentioned pulse-modulated signal generative circuit; Control the order of the conducting cut-off state of above-mentioned a plurality of switching circuits based on above-mentioned back electromotive force detection signal, and at least one of high-side switch that above-mentioned a plurality of switching circuit comprised and low side switch carried out switch control based on above-mentioned pulse-modulated signal;

The window signal generative circuit; Reception is from the above-mentioned back electromotive force detection signal of above-mentioned counter electromotive force detection circuit with from the above-mentioned pulse signal of above-mentioned pulse signal generative circuit; Output becomes predetermined level after detecting certain back electromotive force detection signal, when having detected m above-mentioned pulse signal; When detecting next back electromotive force detection signal, become the window signal of the level that is different from above-mentioned predetermined level afterwards, wherein m is the integer that satisfies m＜n;

Above-mentioned ON-OFF control circuit receives the above-mentioned window signal from above-mentioned window signal generative circuit; This window signal be above-mentioned predetermined level during; The switch motion of the said switching circuit that stops to be connected with the coil of being kept watch on back electromotive force by above-mentioned counter electromotive force detection circuit is set at high-impedance state.

21. motor-drive circuit according to claim 20 is characterized in that:

Above-mentioned sine wave signal generative circuit comprises the storage part of preserving above-mentioned sinuous control signal, and reads above-mentioned sinuous control signal successively according to above-mentioned pulse signal and export.

22., it is characterized in that according to claim 20 or 21 described motor-drive circuits:

Above-mentioned pulse-modulated signal generative circuit comprises

Synthetic portion, output with the phase multiplication with above-mentioned control signal and above-mentioned dtc signal the composite signal after synthetic;

Pulse modulator will compare with predetermined periodic signal from the above-mentioned composite signal of above-mentioned synthetic portion, generates the above-mentioned pulse-modulated signal that duty ratio changes according to its magnitude relationship.

23., it is characterized in that according to claim 20 or 21 described motor-drive circuits:

Above-mentioned pulse signal generative circuit comprises

Clock signal generating circuit, the pulse signal of the n overtones band of the frequency that generation said frequencies counter is measured.

24. motor-drive circuit according to claim 23 is characterized in that:

Past K time the frequency values that above-mentioned clock signal generating circuit is measured the said frequencies counter carries out computing, and sets the frequency of the pulse signal that should generate according to the result of computing, and wherein K is the integer more than 1.

25. motor-drive circuit according to claim 24 is characterized in that:

Above-mentioned clock signal generating circuit has the adjusting device of above-mentioned integer K.

26. motor-drive circuit according to claim 24 is characterized in that:

Above-mentioned pulse signal generative circuit also comprises

Storage part is preserved L time frequency values in the past, wherein L be satisfy L >=K integer and

Operational part based on the frequency values that above-mentioned storage part is preserved, is carried out predetermined computing;

The pulse signal of the operation result correspondent frequency of above-mentioned clock signal generating circuit generation and above-mentioned operational part.

27. motor-drive circuit according to claim 26 is characterized in that:

Above-mentioned storage part is a L level shift register.

28. motor-drive circuit according to claim 26 is characterized in that:

29. motor-drive circuit according to claim 20 is characterized in that:

Above-mentioned window signal generative circuit has the adjusting device of above-mentioned integer m.

30. motor-drive circuit according to claim 20 is characterized in that:

Above-mentioned window signal generative circuit comprises

Counter; Reception is from the above-mentioned back electromotive force detection signal of above-mentioned counter electromotive force detection circuit with from the above-mentioned pulse signal of above-mentioned pulse signal generative circuit; Output becomes predetermined level after detect certain back electromotive force detection signal, when having counted m above-mentioned pulse signal unlatching along signal and

31., it is characterized in that according to claim 20 or 21 described motor-drive circuits:

Integrated on a Semiconductor substrate.

32. a dish device is characterized in that, comprising:

Make the spindle motor of disc spins; With

Drive the claim 20 or the 21 described motor-drive circuits of above-mentioned spindle motor.

33. a driving method that provides drive current to drive to polyphase machine is characterized in that, comprising:

The back electromotive force that is produced at least one coil with above-mentioned polyphase machine and the mid-point voltage of coil compare, and detect zero cross point, generate the step of the back electromotive force detection signal of predetermined level;

Generate with above-mentioned back electromotive force detection signal synchronously and frequency be the step of the n pulse signal doubly of above-mentioned back electromotive force detection signal, wherein n is the integer more than 2;

Generate the step of sinuous control signal according to above-mentioned pulse signal;

Above-mentioned control signal is synthetic with the dtc signal of the target torque of the above-mentioned polyphase machine of indication, generate the step of having carried out pulse modulated pulse-modulated signal; And

Control becomes the order of the coil of driven object based on above-mentioned back electromotive force detection signal, and based on above-mentioned pulse-modulated signal, and the above-mentioned coil that becomes driven object is applied the step of high level or low level switching signal,

Be created on after detecting certain back electromotive force detection signal, become predetermined level when having detected m above-mentioned pulse signal, when detecting next back electromotive force detection signal, become the step of the window signal of the level that is different from above-mentioned predetermined level afterwards, wherein m is the integer that satisfies m＜n; With

Above-mentioned window signal be above-mentioned predetermined level during, will with kept watch on the step that switching circuit that the coil of back electromotive force be connected set high-impedance state for for detecting zero cross point.