JP2000287479A - Controller for brushless motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable detection of a zero-crossing point of an induced voltage even under control performed by a PWM control signal, by outputting a zero- crossing signal when the time interval from detection of a rise detection signal up to detection of a first rise detection signal after that is a constant time or longer. SOLUTION: A zero-crossing detecting means 134 detects the time interval from inputting of rise detection signal S1 from a state-change judging means 133 up to inputting of a fall detection signal S2. If it is shorter than the tie width of generation of a surge pulse, a reset signal RST is outputted at the timing of the fall signal S2. If it is longer, a zero-crossing signal ZERO is outputted at the timing of the fall signal S2. Accordingly, information on a zero-crossing point Tz is obtained, by taking out data of measured time obtained by a time measuring means 135, when the zero-crossing signal ZERO is outputted from a zero-crossing detecting means 134. Consequently, detection of zero- crossing points of an induced voltage becomes feasible even under voltage control by PWM.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control device for a brushless motor whose output is variably controlled by PWM control, which detects a position of a permanent magnet rotor without a sensor and performs phase switching in synchronization with rotation of the permanent magnet rotor. The present invention relates to a control device for controlling a brushless motor.

[0002]

2. Description of the Related Art In general, a control device for a brushless motor includes:
A DC power supply is chopped by a drive control circuit composed of switching elements (commutator elements) and the like, and current is sequentially supplied to a plurality of stator windings of the brushless motor, thereby generating a rotating magnetic field in the stator of the brushless motor. It is configured to rotate a rotor (permanent magnet rotor). At this time, the control signal (phase switching signal) given to the drive control circuit needs to be an appropriate signal synchronized with the rotation state of the rotor. Therefore, a position sensor such as a Hall element is provided on the stator, and the rotation position of the rotor is adjusted. Is configured to be detected.

However, in recent years, a sensorless brushless motor control device has been researched and developed to detect the rotational position of the rotor without using a position sensor such as a Hall element.

The principle of detecting the rotor rotational position in such a sensorless brushless motor control device will be described below with reference to FIG.

[0005] FIG. 3 is a diagram showing a case where the conventional PWM control is not performed.
It is each voltage waveform diagram of a phase.

In FIG. 3, reference numeral 201 denotes a terminal voltage waveform;
02 is the reference voltage, 203 is the output of the comparator when the reference voltage 202 is compared with the terminal voltage by the comparator, and 204 is the zero cross point.

The rotation position of the rotor in the sensorless driving is detected by detecting a terminal voltage generated in a stator winding of the brushless motor in accordance with the rotation of the rotor, and detecting a timing at which this terminal voltage matches a preset reference voltage 202. Thus, the detection is performed by detecting the phase of the zero cross point of the induced voltage of the stator winding, and thereby detecting the predetermined rotational position of the rotor.

In this method, when a continuous ON signal is output as a phase switching signal during the period of energizing the stator winding, the terminal voltage of the stator winding can be continuously detected, so that the zero-crossing point is obtained. Can be detected, but PWM
In a case where a pulse width modulated drive current which repeats ON-OFF with a fast cycle is applied to the stator winding by a phase switching signal subjected to pulse width modulation as in a control method or the like, the stator is left as it is. The terminal voltage of the winding cannot be detected. That is, when a pulse-width-modulated drive current is applied throughout the current supply to the stator winding, the terminal voltage generated at the terminal of the stator winding also crosses the reference voltage many times as shown in FIG. As described above, the zero-cross point 204 of the induced voltage cannot be detected as it is.

Therefore, even when an intermittent phase switching signal is output by such a PWM control method or the like, the PWM control signal is turned off in order to detect the zero cross point of the induced voltage of the stator winding. During this period, that is, during the period when the induced voltage of the stator winding cannot be detected, zero crossing point can be detected by not performing the comparison operation between the induced voltage of the stator winding and the reference voltage. A control device for a brushless motor is disclosed.

Next, a method of detecting a zero-cross point in such a control device for a brushless motor will be described with reference to the drawings.

FIG. 4 is a diagram showing voltage waveforms for one phase when conventional PWM control is performed.

In FIG. 4, reference numeral 202 denotes a reference voltage;
Is a terminal voltage waveform during PWM control, 206 is a comparator output during PWM control, 207 is an enable signal, 20
8 is a waveform obtained by masking the output 206 of the comparator at the time of PWM control with the enable signal 207, and 204
Is the zero cross point.

In this method, for example, an enable signal 207 for permitting detection only during a period in which the induced voltage of the stator winding can be detected based on a PWM control signal is generated,
A detection operation is performed based on the enable signal 207.

For example, a conventional P using such a method
As a brushless motor control device under WM control, Japanese Patent Application Laid-Open No. Hei 5-91790 (hereinafter referred to as “A”) discloses an output for supplying an intermittent drive voltage to a stator winding under control of a control signal. In a brushless motor provided with a circuit, position detection means for detecting a rotation position of a rotor by comparing a terminal voltage of the stator winding with a reference voltage during an output period of an enable signal from an enable signal generation means is provided. Wherein the enable signal generating means includes a time constant circuit for generating the enable signal by delaying the rise time and the fall time when receiving the control signal. Is disclosed.

FIG. 5 is a diagram showing a zero-cross point detection period of the induced voltage when the PWM control of the brushless motor disclosed in the Japanese Patent Publication No. A is performed.

In FIG. 5, (a) is a waveform of a terminal voltage of a stator winding in one phase, (b) is a waveform of a PWM control signal, (c) is a waveform of an enable signal, and Ta is PWM.
Delay time from ON of control signal to start of generation of induced voltage,
Tb is the delay time from the turning off of the PWM control signal to the elimination of the induced voltage, Tc is the shift amount from ON of the PWM control signal to ON of the enable signal, and Td is the shift amount from OFF of the PWM control signal to OFF of the enable signal. It is.

In order to set a period during which the induced voltage of the stator winding can be reliably detected, the enable signal is set to a period slightly smaller than the output period of the induced voltage of the stator winding as shown in FIG. good. As a result, the enable signal has a delay time Tc which is slightly longer than Ta which is a delay time from ON of the PWM control signal to the start of generation of the induced voltage.
Is set as the start timing, and the end timing is set as the time when a delay time Td slightly shorter than the delay time Tb from when the PWM control signal is turned off to when the induced voltage disappears disappears. Therefore, in such a brushless motor control device, it is necessary to provide a time constant circuit for determining a time constant on a circuit in order to generate the delay time.

[0018]

However, the above-mentioned conventional brushless motor control device has the following problems.

(1) When a conventional brushless motor control device is configured to use a microcomputer and use an enable signal as an interrupt signal, a zero-cross point comes during a period in which the enable signal is ON. During the ON period, there is a problem that the microcomputer cannot be effectively used for other processing.

(2) The brushless motor can be rotated by determining the commutation timing using the detected zero-cross point and performing phase switching control. In the conventional control device, however, the means for phase switching control is as follows. There is a problem that a configuration for phase switching control is required separately.

The present invention solves the above-mentioned conventional problems. Under a control by a PWM control signal, a zero-cross point of an induced voltage can be detected by a simple configuration, and a phase switching control can be performed. To provide a control device for a brushless motor that can effectively utilize a microcomputer when used and can be realized only by a microcomputer program without separately requiring a configuration for phase switching control. With the goal.

[0022]

SUMMARY OF THE INVENTION In order to solve the above problems, a control device for a brushless motor according to the present invention comprises a plurality of phases of a stator winding for generating a driving magnetic field by applying a driving current, and a stator winding for the stator winding. A brushless motor having a permanent magnet rotor that is rotationally driven by a generated driving magnetic field.
A control device for a brushless motor driven by M control, wherein an open-phase voltage synthesizing means for selecting an open-phase stator winding to which a driving current is not applied at each time point and outputting a terminal voltage thereof as a synthetic waveform voltage; Neutral potential setting means for setting the neutral potential of the terminal voltage of the stator winding, comparison means for comparing the composite waveform voltage with the neutral potential and outputting a comparison signal, and when switching the phase of the drive current of the drive current A back electromotive waveform removal means for removing a surge pulse generated in the comparison signal from the comparison signal and outputting it as a position detection signal; and outputting a rise detection signal when a rise of the position detection signal is detected and detecting a fall of the position detection signal. State change determining means for outputting a rise detection signal when detected, and a time interval T from the detection of the rise detection signal to the first detection of the rise detection signal thereafter
If ₁₂ of the measured time interval T ₁₂ is more than a predetermined time consisting configuration comprising a zero-cross detection means for outputting a zero-cross signal.

With this configuration, even under the control by the PWM control signal, the zero-cross point of the induced voltage can be detected with a simple configuration, phase switching control is possible, and when a microcomputer is used, the microcomputer is effective. It is possible to provide a control device for a brushless motor that can be realized only by a microcomputer program without requiring a separate configuration for phase switching control.

[0024]

In order to achieve this object, a control device for a brushless motor according to a first aspect of the present invention comprises: a plurality of stator windings for generating a driving magnetic field by supplying a driving current; And a permanent magnet rotor rotatably driven by a driving magnetic field generated by a slave winding. A brushless motor control device that drives a brushless motor by PWM control, wherein the drive current is not supplied at each time. Open voltage synthesizing means for selecting a phase stator winding and outputting its terminal voltage as a synthetic waveform voltage; neutral potential setting means for setting a neutral potential of the terminal voltage of the stator winding; A comparison means for comparing with a neutral potential and outputting a comparison signal; and a surge pulse generated at the time of drive current phase switching of the drive current is removed from the comparison signal and output as a position detection signal. Back electromotive waveform removing means, state change discriminating means for outputting a rise detection signal when detecting the rise of the position detection signal, and outputting a rise detection signal when detecting the fall of the position detection signal, then from the detection of the detection signal first rising detection signal in time interval T ₁₂ measures the time interval T ₁₂ until the detecting is provided with a zero-cross detecting means for outputting a zero-cross signal in the case of more than a certain time With this configuration, the following effects can be obtained.

(1) The rotation of the permanent magnet rotor of the brushless motor generates an induced voltage in the stator winding of each phase. Among the stator windings, only the induced voltage induced by the rotation of the permanent magnet rotor is observed at the terminals of the stator windings of the phase in which the drive current is not supplied at each time and the phase is open. Is done. The open-circuit voltage synthesizing means selects the open-phase stator winding at each time point, detects the terminal voltage thereof, and outputs it as a synthetic waveform voltage. The comparison means is
It compares the composite waveform voltage with the neutral potential and outputs a comparison signal. In this comparison signal, in addition to the information of the zero crossing point, P
The waveform includes a waveform due to intermittent ON-OFF of the drive voltage at the time of WM control, and a surge pulse due to a back electromotive voltage generated in the stator winding at the time of phase switching. The surge pulse appears on the comparison signal as a pulse having a certain period of time immediately after the phase switching is performed. The back electromotive waveform removing means removes the surge pulse from the comparison signal and outputs it as a position detection signal. The state change determining means outputs a rise detection signal when detecting a rise of the position detection signal, and outputs a fall detection signal when detecting a fall of the position detection signal. The position detection signal includes an intermittent ON-state of the drive voltage during PWM control in a section where the induced voltage is equal to or lower than the neutral potential.
A waveform due to OFF is included, and a high state is always maintained in a section where the induced voltage is equal to or higher than the neutral potential. Accordingly, the time interval between the rise and fall of the position detection signal is set to an intermittent ON-interval when the induced voltage is equal to or lower than the neutral potential.
Since the interval is the interval of the waveform due to OFF, the interval is short, and in the interval where the induced voltage is equal to or higher than the neutral potential, the interval is between zero-cross points. Zero-cross detection means, then from the detection of the rising detection signal initially measures the time interval T ₁₂ until detection of the rising detection signal, if the time interval T ₁₂ is less than a predetermined time intermittent ON- outputs a reset signal it is determined that due to OFF, the time interval T ₁₂ outputs a determination zero cross signal as the time interval between zero-crossing points in the case of more than a certain time. This makes it possible to detect a zero-cross point where the induced voltage crosses the neutral potential. Thus, the rotation position of the permanent magnet rotor can be detected, and the phase switching can be controlled in synchronization with the rotation of the permanent magnet rotor.

(2) The driving voltage applied to the stator winding is P
Even in the case of intermittent supply by WM control, the zero cross point of the induced voltage induced in the stator winding can be detected with a simple configuration, and the drive current can be phase-switched at an appropriate timing. Phase switching can be controlled.

(3) It is possible to configure using a microcomputer. In this case, the microcomputer can be used effectively, and a configuration for phase switching control is not separately required, and it is realized only by a program of the microcomputer. It is also possible,
The structure can be made compact and the economy is excellent.

Here, the brushless motor has two phases or three phases.
A phaseless, five-phase, seven-phase, etc. sensorless type is used. Also, a star-connected bipolar drive brushless motor, a delta-connection bipolar drive brushless motor, a unipolar drive brushless motor, or the like is used.

The switching of the drive current is performed by a commutator element including a switching element such as a bipolar transistor or a MOS transistor, using a drive control circuit that switches the phase of the drive current flowing through the stator winding.

The open-circuit voltage synthesizing means selects a terminal of the open-phase stator winding by a switching element or a multiplexer in synchronization with the phase switching of the drive current, and outputs an induced voltage generated at the terminal as a synthetic waveform voltage. Such a configuration is used.

The back electromotive waveform removing means is constructed by synchronizing with the phase switching of the drive current, generating pulses at fixed intervals from the time when the phase switching is performed, and masking the comparison signal with the pulses. Alternatively, a configuration is used in which a signal change is locked so as not to accept a signal change for a certain period of time after the phase switching is performed.

The neutral potential setting means includes a configuration for generating a neutral potential from a neutral point of a driving voltage applied to the stator winding by a voltage dividing circuit using a resistor, and a driving terminal for the stator winding. For example, a configuration that takes the neutral point of the voltage generated at the time is used.

According to a second aspect of the present invention, there is provided the control device for a brushless motor according to the first aspect, wherein the elapsed time from the last detection of the rising detection signal to the detection of the zero-cross signal is measured. Time measuring means for outputting as a zero-crossing point interval, commutation timing measuring means for determining the timing of phase switching of the drive current from the zero-crossing point interval, and phase switching timing of the driving current determined by the commutation timing measuring means. And a phase switching control means for switching the phase of the drive current. With this configuration, the following operation can be obtained.

(1) When the zero-cross signal is detected after the rise detection signal is detected before the next rise detection signal is detected after the rise detection signal is detected, the time measurement means is provided after the last rise detection signal is detected. The measured value of the elapsed time until the zero cross signal is detected is output as the zero cross point interval. The commutation timing measuring means determines the phase switching timing of the drive current from the zero-cross point interval.

(2) Since the zero-cross point can be accurately detected by a simple function and configuration, and temporal information between the zero-cross points that can be used to determine the timing of phase switching of the drive current can be detected. This has the effect of simplifying the configuration and enabling stable phase switching control.

Here, as means for the commutation timing measuring means to determine the phase switching timing of the drive current,
Means for measuring the time from the detection of the zero-cross signal and performing phase switching when the time becomes １ ／ or 又 は of the zero-cross point interval is used.

According to a third aspect of the present invention, in the control device for a brushless motor according to the second aspect, the commutation timing measuring means starts time measurement from the time when the zero cross signal is generated, and measures the time. A first commutation timing measuring means for outputting a commutation timing signal P1 at a time when the time reaches one-fourth of a zero-cross point interval obtained by the measuring means; and the phase switching control means receives the commutation timing signal P1. Then, the drive current phase switching is performed. With this configuration, it is possible to determine the appropriate drive current phase switching timing based on the time information between the immediately preceding zero-cross points. This has the effect that stable phase switching control can be performed at all times even when fluctuations occur.

According to a fourth aspect of the present invention, there is provided the brushless motor control device according to the third aspect, wherein the commutation timing measuring means starts time measurement when the commutation timing signal P1 is detected. A second commutation timing measuring means for outputting a commutation timing signal P2 at a time when a half of the zero cross point interval is reached, wherein the phase switching control means comprises a commutation timing signal P1 or a commutation timing signal P2;
2 is input, the phase of the drive current is switched. With this configuration, the phase switching of the first and second drive currents after the detection of the zero-cross point can be controlled. Thus, the switching of the drive current phase can be controlled at an appropriate timing.

An embodiment of the present invention will be described below with reference to the drawings.

(Embodiment 1) FIG. 1 is a block diagram showing a device configuration of a control device for a brushless motor according to Embodiment 1 of the present invention.

In FIG. 1, reference numeral 101 denotes a stator of a brushless motor, 102u, 102v, and 102w denote three-phase star-connected stator windings for generating a driving magnetic field in the stator 101; A rotor 104 driven to rotate by a magnetic field generated by the windings 102u, 102v, and 102w includes a stator winding 102u,
A drive control circuit connected to the terminals U, V, and W of 102v and 102w to generate a drive current flowing through each stator winding;
5 to 110 are stator windings 102u, 102v, 102w
Commutator elements for switching the drive currents i _u , i _v , i _w to flow through, and 111 to 116 are commutator elements 105
Freewheeling diodes to release the surge voltage generated by switching to 110, 117 voltage for driving the stator 101 (hereinafter, referred to as a driving voltage V _S.) DC power supply for supplying, 117a may generate a DC voltage The DC voltage source 117b is a capacitor for removing noise of the DC voltage source 117a and stabilizing the output voltage, 118 is a negative bus, and 119 is a positive bus.

High-side commutator elements 105-1
07 is an NPN transistor, and the low-side commutator elements 108 to 110 are PNP transistors. Stator windings 102u, 102v, 10
One terminal O (hereinafter, referred to as a common terminal) of 2w is commonly connected, and the other terminals U, V, W (hereinafter, referred to as drive terminals) are each connected to the drive terminal U by a commutator element 10.
Common connection point of 5 and 108 (collector side of both elements) O _U
And the drive terminal V is connected to the commutator element 10
Common connection point of 6 and 109 (collector side of both elements) O _V
And the drive terminal W is connected to the commutator element 10
Common connection point of 7 and 110 (collector side of both elements) O _W
It is connected to the. The negative side of the DC power supply 117 is connected to the negative side bus 118, and the positive side is connected to the positive side bus 119. The high-side commutator element 10
The emitters 5 to 107 are connected to the positive bus 119, and the collectors of the low-side commutator elements 108 to 110 are connected to the negative bus 118.

The DC voltage source 117a converts a voltage level from a commercial power supply using a transformer to rectify the voltage, a rectifier without a transformer, a rectifier by switching control, a battery, etc. Anything can be used as long as it generates.

Reference numeral 120 denotes a neutral potential generating resistor 120U, 12
The potential of neutral point of which is constituted by the voltage dividing circuit by 0L terminal voltage of the DC power source 117 (driving voltage V _S) (hereinafter, referred to as the neutral potential V _N.) Is a neutral potential setting means for generating.
Neutral potential generating resistor 120U and neutral potential generating resistor 120
L and they are connected one to each other at the connection point O _N, the other end of the neutral potential generating resistor 120U is positive-side bus 11
9, and the other end of the neutral potential generating resistor 120 </ b> L is connected to the negative bus 118. Neutral potential generating resistor 12
The 0U and neutral potential generating resistor 120L, the resistance value so as to generate a neutral potential V _N is adjusted at the connection point O _N of each other are connected.

In the first embodiment, the DC power supply 11 is provided by a voltage dividing circuit including the neutral potential generating resistors 120U and 120L.
Although composed of 7 neutral point of to generate neutral potential V _N, a neutral potential setting means 120 it is not intended to be limited to, the stator windings 102u, 102v, 102w of the drive pin The configuration may be such that the neutral points of the voltages generated at U, V, and W (hereinafter, referred to as drive terminal voltages V _u0 , V _v0 , V _w0 ) are obtained.

Reference numeral 121 denotes stator windings 102u, 102v,
Open phase synthesizing means for detecting the drive terminal voltage of the open phase (phase corresponding to the drive terminal in which both the connected high-side commutator element and low-side commutator element are in the OFF state) out of 102w, 122, 12
Reference numerals 3 and 124 denote voltage detection switching elements, each of which is formed of an NPN transistor, for selecting a drive terminal (any one of the drive terminals U, V, and W) which is an open phase. Reference numeral 125 denotes voltage detection switching elements 122, 123, and 123. Amplifiers for amplifying the switching control signal input to the base terminal of the switch 124, and drive terminals (drive terminals U, V, W) which are open phases selected by the voltage detection switching elements 122, 123, 124 are provided. R _U2 , a diode provided to output the voltage of any one of
R _V2 and R _W2 are voltage dividing resistors provided to suppress the output of the open-phase synthesizing means 121 to a certain voltage or less.

Voltage detection switching elements 122, 12
The emitter terminal of 3,124 is grounded, the collector terminal are connected resistors R _U1, R _V1, through the R _W1 driving terminals U, V, in W. Each of the connection points of the voltage detection switching element collector terminal of the 122, 123 and 124 and the resistor _{R U1, R V1, R W1} , diode 12
One end of each of the anode terminals 6, 127, 128 and the voltage dividing resistors R _U2 , R _V2 , R _W2 is connected, and the other ends of the voltage dividing resistors R _U2 , R _V2 , R _W2 are grounded. Amplifier 1
25 three output terminals are the voltage detection switching element 1
22, 123 and 124 are connected to the base terminals.
The cathode terminals of the diodes 126, 127, and 128 are commonly connected, and this is the output terminal of the open-phase synthesizing means 121.

Here, the voltage detection switching element 12
2, 123 and 124 do not need to be transistors, as long as the resistance is small in a conductive state.
An FET, a switching IC, a reed relay, or the like may be used.

Numeral 129 denotes a comparing means comprising a comparator, whose negative input terminal is connected to the neutral potential generating resistor 12.
The 0U and neutral potential generating resistor 120L is connected to the connection point O _N, the positive input terminal is connected to the output terminal of the resistor R ₃ open-phase combining means 121 via the. The comparing means 129 compares the composite waveform voltage V ₀ of the drive terminal voltage in the open phase output from the open phase synthesizing means 121 with the neutral potential V _N, and outputs the result of the comparison as a comparison signal.

Reference numeral 130 denotes a back electromotive waveform removing means for removing a pulse due to a back electromotive voltage generated in the stator windings 102u, 102v, 102w from the comparison signal from the comparing means 129;
Reference numeral 1 denotes a one-shot pulse generator that generates a pulse having a fixed time width synchronized with a pulse generated by a back electromotive force generated in the stator windings 102u, 102v, and 102w.
Is the output of the one-shot pulse generator 131 and the comparing means 1
29 is an OR circuit which generates an OR logic of the signal is output as the position detection signal V _p of the output of.

The output terminal of the OR circuit 132 is the output terminal of the back electromotive waveform removing means 130,
The OR logic signal of the output of the one-shot pulse generator 131 and the output of the comparing means 129 is output from the back electromotive waveform removing means 130.

133 is an output signal of the back electromotive waveform removing means 130.
Signal rising and output signal falling respectively.
A state change judgment that outputs each detection signal S1 and S2
Another means 134 is an output signal S of the state change determining means 133.
1 (Detection signal of rising edge of output signal. Hereinafter, rising edge detection
Called signal S1. ) And output signal S2 (falling of output signal)
Galling detection signal. Hereinafter, this signal is referred to as a fall detection signal S2. )When
Time interval T₁₂And the time interval T₁₂Is within a certain time
In this case, the reset signal RST is output and the time interval T ₁₂Is constant
If the time is exceeded, it is determined that a zero-cross point has been detected
-Cross detection that outputs zero-cross signal ZERO
Means 135 is a rise detection signal of the state change determining means 133
Time measurement starts with S1 as a trigger signal and zero-cross detection
The zero cross signal ZERO output from the means 134 is detected.
Time T until_Z(Hereinafter, the zero-cross point interval T_ZCall
Huh. ) And every time the reset signal RST is input
This is a time measuring means for resetting the measured value.

The time measuring means 135 calculates the zero-cross point interval T
_{When Z} is detected, measurement data of the zero-cross point interval T _Z and half the time T _Z / 4 is output.

Reference numeral 136 denotes a timing when commencement of measurement data of a time T _Z / 4 of の of the zero-cross point interval from the time measuring means 135 and commutation timing when the measurement time coincides with T _Z / 4. The first commutation timing measuring means 137 for outputting the signal P1 is a first commutation timing measuring means 13
6 The outputs of the commutation timing signal P2 when the commutation timing signal P1 is inputted starts counting the measured time coincides with the half of the zero-crossing point interval T _Z inputted from the time measuring means 135 from 2 means for measuring commutation timing,
138 is the first commutation timing measuring means 136 and the second
When the commutation timing signals P1 and P2 output from the commutation timing measurement unit 137 are input, a drive pattern that generates a rotational force in the rotor 103 is generated and is applied to the base terminals of the commutator elements 105 to 110 of the drive control circuit 104. On the other hand, the six-phase control signals UH, UL, VH, VL, WH,
Output WL and one-shot pulse generator 13
1 and the amplifier 125 for the open phase combined drive signal V _A ,
Phase switching control means for outputting V _B and V _C.

The phase switching control means 138 includes the drive control circuit 1
04, the six-phase control signals UH, UL, VH, VL,
By performing pulse width modulation on WH and WL, PWM control of the brushless motor is performed.

The operation of the control device for the brushless motor according to the first embodiment configured as described above will be described below.

FIG. 2 is a diagram showing signal waveforms at various parts in FIG.

In FIG. 2, (a) to (c) show waveforms of the drive terminal voltages V _u0 , V _v0 , V _w0 , and (d) to (i) show six-phase control signals UH, VH, WH, UL, VL. , the waveform of the components excluding a PWM modulated wave WL, (j) ~ (l ) is released phase combined drive signals V _a, V _B, V _C of the waveform, (m) is released to the output of the open-phase combining means 121 The waveform of the composite waveform voltage V ₀ of the drive terminal voltages to be phased, (n) is the output waveform of the one-shot pulse generator 131, (o) is the output waveform of the OR circuit 132, and (p) is the output of the zero-cross detecting means 134 The reset signal RST, (q) is the zero-cross signal ZERO output from the zero-cross detecting means 134.

When the brushless motor is driven by PWM control, the drive terminals U, V, W have drive terminal voltages V _u0 , V _u as shown in FIGS. 2 (a) to 2 (c).
_v0 and _Vw0 are generated.

In FIGS. 2A to 2C, T _1u ,
T _1v and T _1w are driven by the drive control circuit 104 toward the stator windings 102 u, 102 v, and 102 w in the positive direction (directions from the drive terminals U, V, W to the common terminal O), and drive currents i _u , i _v , i. _w is the period during which _w is forced to flow, and T _2u ,
T _2v, T _2w each stator winding 102u by the drive control circuit 104, 102v, negative direction 102w drive current i _u (the drive terminal U from the common terminal O, V, toward the W), i _v, i _This is the period during which _w is forced to flow. The phase switching control means 138 controls the six-phase control UH, which is a waveform obtained by superposing a PWM modulation wave on the waveforms shown in (d) to (i).
VH, WH, UL, VL, WL are output, and the phase switching of the drive currents i _u , _iv , i _w is performed by six-phase control UH, VH,
Commutator element 105 using WH, UL, VL, WL
１１０110 is performed. A is a commutation point at which phase switching of the drive currents i _u , i _v , i _w is performed by switching of the commutator elements 105 to 110, and T _pu , T _pv , and T _pw are fixed by the commutation of the drive current. This represents a generation period of a surge pulse generated when a surge current flows through the freewheeling diodes 111 to 116 due to a back electromotive voltage generated in the slave windings 102u, 102v, and 102w.

Output patterns for six-phase control are prepared in time series in advance in the phase switching control means 138. When the commutation timing signals P1 and P2 are input, the output pattern is changed to the next output pattern. -Phase control UH, VH, WH, UL, VL, WL
Are output in accordance with the output pattern, whereby (j) to (j) in FIG.
The open-phase combined drive signals V _A , V _B , V as shown in FIG.
Output _C. These output patterns of the phase switching control means 138 may be switched by hardware using a counter or a digital circuit, or may be switched using software by a program of a microcomputer.

The open-phase synthesizing means 121 receives the open-phase synthesized driving signals V _A , V _B , and V _C from the phase switching control means 138, and the amplifier 125 amplifies the signals and outputs a voltage detection switching element 122. , 123,124
Input to the base terminal of Phase switching control means 138, releasing phase combined drive signals V _A, V _B, of V _C, the signal inputted to the one corresponding to the release phase of the voltage detection switching elements 122, 123, and 124 are LOW state, it The signals other than the above are switched to the open-phase combined drive signals V _A , V _B , and V _C so that the signals become HIGH. As a result, a voltage proportional to the drive voltage is generated at the collector terminal of one of the voltage detection switching elements 122, 123, and 124 corresponding to the open phase, and the other collector terminals are substantially at the ground potential. Accordingly, a voltage proportional to the drive voltage in the open phase is always output to the output terminal of the open-phase combining means 121 as the combined waveform voltage V ₀ .

For example, when the U-phase is the open phase, the open-phase combined drive signals V _B and V _C become HIGH, the open-phase combined drive signal _VA becomes LOW, and the voltage detection switching elements 123 and 124 are turned on. (Conduction state), the voltage detection switching element 122 is turned off (non-conduction state). At this time, a voltage proportional to the drive terminal voltage V _u0 is generated at the collector side terminal of the voltage detection switching element 122 corresponding to the U phase, and the collector side terminals of the voltage detection switching elements 123 and 124 corresponding to the V phase and the W phase. Are connected with a low resistance, and have a substantially ground potential. Therefore, the diodes 127 and 128 become non-conductive, and the diode 126
Only the terminal voltage of the collector side terminal of the voltage detection switching element 122 corresponding to the U phase is input to the comparing means 129 because only the terminal is in the conductive state. Similarly, when the V phase and the W phase are open phases, the drive voltage of the open phase can be selectively input to the comparing means 129.

FIG. 2 (m) shows a composite waveform voltage V ₀ of the terminal voltage waveform selectively synthesized by the open-phase synthesizing means 121, and this waveform is input to the comparing means 129. As a result, the output waveform of the comparing means 129 is a comparison result between the composite waveform voltage V ₀ of the induced voltage waveforms of the U, V, and W phases at the time of the open phase and the neutral potential V _N. The information of the zero cross point is included.

The one-shot pulse generator 131 of the back electromotive waveform removing means 130 outputs the open-phase combined drive signals V _A , V _B , V
_{At the} point where the phase switching of _C is performed, a pulse having a certain time width (hereinafter, referred to as a one-shot pulse signal) is output.

[0066] FIG. 2 (n) is the output waveform of the one-shot pulse generator 131 of the back electromotive waveform removing means 130, synchronized release phase combined drive signals V _A, V _B, the phase switching timing V _C A one-shot pulse signal which is set to a HIGH state only for a predetermined time is output. HI in this case
The time width of the GH state is determined according to the size of the brushless motor, the inductance of the stator windings 102u, 102v, 102w, the values of the drive currents i _u , i _v , i _w , the number of rotations, and other operating conditions. The width is determined to be slightly longer than the surge pulse widths T _pu , T _pv , and T _pw .

The OR circuit 132 synthesizes an OR logic signal (position detection signal V _p ) of the output of the one-shot pulse generator 131 and the output of the comparing means 129 and outputs it to the state change judging means 133 (FIG. 9). 2 (o)).

[0068] status change determining means 133 detects a rise timing of the position detection signal V _p of the signal, and outputs the zero-cross detection means 134 and the time measuring means 135 and the timing as the rising detection signal S1. Further, the state change determining means 133 detects the falling timing of the position detection signal _Vp , and outputs the detected timing to the zero-cross detecting means 134 as a falling detection signal S2.

The zero-cross detecting means 134 detects a time interval from the input of the rising detection signal S1 from the state change determining means 133 to the input of the falling detection signal S2,
For example, similarly to the one-shot pulse signal, when the time interval is shorter than the generation time widths T _pu , T _pv , and T _pw of the surge pulse, the reset signal is generated at the timing of the falling detection signal S2 when the time interval is shorter than the reference time. Output RST (Fig. 2 (p)
), The fall detection signal S
The zero-cross signal ZERO is output at the timing of 2 (see FIG. 2 (q)). Therefore, the time measuring means 135
As a result, the longest time width T _Z in the position detection signal V _p is measured, and this time length is the time between zero cross points from the zero cross point to the next zero cross point (that is, the zero cross point). This is the same as the point interval T _Z ). That is, when the output of the zero cross signal ZERO from the zero-cross detection means 134, by retrieving the data of the measurement time measured in the time measuring means 135, it is possible to obtain information of the zero-crossing point interval T _Z.

The time measuring means 135 detects the zero-cross point.
And the measured zero-cross point interval T _ZHalf the time T_Z/
2 is output to the first commutation timing measuring means 136.

Here, as a method of obtaining data of a time T _Z / 2 which is half of the zero cross point interval T _Z , a method of shifting binary data is used.

The first commutation timing measuring means 136 starts time measurement when data of the time interval T _Z / 4 is input from the time measuring means 135, and the measured time t is changed to the time interval T _Z / 4. At this point, a commutation timing signal P1 is output to the phase switching control means 138 and the second commutation timing measurement means 137.

When the commutation timing signal P1 is input, the phase switching control means 138 controls the six-phase control signals UH, VH, W
H, UL, VL, WL phase switching is performed.

Before the commutation timing signal P1 is input from the first commutation timing measurement means 136, the second commutation timing measurement means 137 outputs the zero-cross point interval T from the time measurement means 135 at the zero-cross point in advance. _When 1/2 of _Z is input and the commutation timing signal P1 synchronized with the phase switching timing of the drive current is input from the first commutation timing measurement unit 136, time measurement starts, and the measured time t is 1/0 of the zero-cross point interval T _Z
At the time of coincidence with 2, the commutation timing signal P2 is output to the phase switching control means 138.

In this embodiment, the first commutation timing measuring means 136 and the second commutation timing measuring means 137
Constitutes a commutation timing measuring means.

When the commutation timing signal P2 is input, the phase switching control means 138 controls the six-phase control signals UH, VH, W
H, UL, VL, WL phase switching is performed.

With the above operation, the phase switching after the detection of the zero-cross point and the phase switching following the phase switching can be performed with good timing, and the six-phase control signals UH, VH, W
Feedback control for phase switching between H, UL, VL, and WL can be stably and continuously performed.

[0078]

As described above, according to the control apparatus for a brushless motor of the present invention, the following advantageous effects can be obtained.

According to the first aspect of the present invention, (1) using a simple configuration and function, even when driving a drive voltage to be intermittently supplied to a stator winding under voltage control by PWM, By using the pulse waveform obtained by comparing the induced voltage of the stator winding with the reference voltage, the zero-cross point of the induced voltage can be detected and the time information between the zero-cross points can be detected. It is possible to provide a control device for a brushless motor that can perform phase switching of a current and operate stably.

(2) It is possible to configure by using a microcomputer. In this case, the microcomputer can be effectively used, and a configuration for phase switching control is not separately required, and is realized only by a program of the microcomputer. It is also possible,
It is possible to provide a brushless motor control device that can be made compact in size and that is economical.

According to the second aspect of the present invention, the zero cross point can be accurately detected with a simple function and configuration, and the temporal information between the zero cross points that can be used for determining the timing of phase switching of the drive current. , It is possible to provide a control device for a brushless motor that can simplify the configuration and perform stable phase switching control.

According to the third aspect of the present invention, it is possible to determine an appropriate drive current phase switching timing based on time information between immediately preceding zero-cross points, so that even if a load change or the like occurs. It is possible to provide a brushless motor control device capable of always performing stable phase switching control.

According to the fourth aspect of the present invention, the first and second phase switching of the drive current after the zero-cross point is detected can be controlled, and as a result, the drive current can always be continuously and at appropriate timing. A control device for a brushless motor capable of controlling phase switching can be provided.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a device configuration of a control device for a brushless motor according to a first embodiment of the present invention;

FIG. 2 is a diagram showing signal waveforms at various parts in FIG. 1;

FIG. 3 is a diagram showing voltage waveforms for one phase when conventional PWM control is not performed.

FIG. 4 is a diagram showing voltage waveforms for one phase when conventional PWM control is performed.

FIG. 5 is a diagram showing a zero-cross point detection period of an induced voltage when PWM control of the brushless motor disclosed in Japanese Patent Publication No. A is applied.

[Explanation of symbols]

101 stator 102u, 102v, 102w stator winding 103 rotor 104 drive control circuit 105, 106, 107, 108, 109, 110 commutator element 111, 112, 113, 114, 115, 116 freewheeling diode 117 DC power supply 117a DC Voltage source 117b Capacitor 118 Negative side bus 119 Positive side bus 120 Neutral potential setting means 120U, 120L Neutral potential generating resistor 121 Open phase synthesizing means 122, 123, 124 Voltage detection switching element 125 Amplifier 126, 127, 128 Diode 129 Comparison Means 130 Back electromotive waveform removing means 131 One shot pulse generator 132 OR circuit 133 State change determining means 134 Zero cross detecting means 135 Time measuring means 136 First commutation timing Grayed measuring unit 137 second commutation timing measuring means 138 phase switching control means i _u, i _v, i _w driving current _{R U1, R V1, R W1} , R 3 resistors R _U2, R _V2, R _W2 dividing resistor V _u0 , V _v0 , V _w0 drive terminal voltage V ₀ combined waveform voltage _VA , V _B , V _C release phase combined drive signal UH, UL, VH, VL, WH, WL Six-phase control signal P1, P2 Commutation timing signal RST reset signal S1 rising detection signal S2 falling under detection signal T _Z zero crossing point interval ZERO zero cross signal 201 terminal voltage waveform 202 reference voltage 203 comparator output 204 zero-cross point 205 terminal voltage waveform 206 comparator output 207 enable the PWM control Signal 208: Waveform detected by masking the output of the comparator during PWM control with an enable signal

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 5H560 BB03 BB04 BB05 BB07 BB08 BB12 DA13 EB01 EB05 GG04 RR06 SS02 SS07 TT01 TT02 TT07 TT15 UA02 UA05 XA12

Claims (4)

[Claims] 1. A brushless device comprising: a plurality of phases of a stator winding for generating a driving magnetic field by applying a driving current; and a permanent magnet rotor rotatably driven by the driving magnetic field generated by the stator winding. What is claimed is: 1. A brushless motor control device for driving a motor by PWM control, comprising: selecting an open-phase stator winding in which said drive current is not supplied at each time, and outputting a terminal voltage thereof as a composite waveform voltage. Synthesizing means, neutral potential setting means for setting a neutral potential of the terminal voltage of the stator winding, comparing means for comparing the synthesized waveform voltage with the neutral potential and outputting a comparison signal, and Back electromotive waveform removing means for removing a surge pulse generated at the time of phase switching of the current drive current from the comparison signal and outputting the same as a position detection signal; State change determining means for outputting a rise detection signal when detecting the rise detection signal and outputting a rise detection signal when detecting the fall of the position detection signal, and first after detecting the rise detection signal, measures the time interval T ₁₂ until detection of the rising detection signal the time interval T ₁₂
And a zero-crossing detecting means for outputting a zero-crossing signal when is longer than a predetermined time. 2. A time measuring means for measuring an elapsed time from when the rise detection signal is finally detected to when the zero cross signal is detected, and outputs the measured time as a zero cross point interval; Commutation timing measurement means for deciding the timing of phase switching, and phase switching control means for performing phase switching of the drive current in accordance with the drive current phase switching timing determined by the commutation timing measurement means. The control device for a brushless motor according to claim 1, wherein: 3. The commutation timing measurement means starts time measurement from the time when the zero-cross signal is generated, and when the measurement time reaches one-fourth of the zero-cross point interval obtained by the time measurement means. Commutation timing signal P1
3. A first commutation timing measurement unit that outputs the first commutation timing, and the phase switching control unit switches the phase of the drive current when the commutation timing signal P1 is input. Control device for brushless motor. 4. The commutation timing measuring means starts time measurement when the commutation timing signal P1 is detected, and when the measurement time reaches a half of the zero-cross point interval, the commutation timing signal P2. And a second commutation timing measuring means for outputting a phase change signal, wherein the phase switching control means switches the phase of the drive current when the commutation timing signal P1 or the commutation timing signal P2 is input. The control device for a brushless motor according to claim 3.