JP2547080B2 - Sinusoidal signal generator for brushless motor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (1) Object of the Invention (Industrial field of application) The present invention relates to a sine wave signal generator for a brushless motor used in a servomotor used for controlling a machine tool or the like, particularly The present invention relates to a sine wave signal generator for a brushless motor having a rotor with a field and an armature with three-phase windings.

(Prior Art) In order to operate a brushless motor having a rotor having a field (generally a permanent magnet) and an armature having three-phase windings as a servo motor, each of the three-phase windings is used. It is necessary to pass a sine wave current corresponding to the magnetic pole position (that is, rotor position) of the permanent magnet facing this line to the wire, and as a means of obtaining this sine wave current, a rotor resolver is attached and the output voltage of this resolver is There is a configuration to use. Since the resolver is an electromagnetic machine, it has a characteristic that the output voltage waveform is good and it is strong against external disturbances. However, the resolver usually has two poles, and it is difficult to correspond to the number of magnetic poles of the servo motor. If so, there is a problem that the cost becomes high. Therefore, an apparatus having the following configuration is being researched as an alternative to the resolver.

This device is provided with a commutation sensor (CS) that detects the magnetic pole position of the field on the rotor shaft of the brushless motor, and an encoder (EC) that finely detects the position of the rotor shaft.
From these (CS) and (EC) signals, the sine wave signal for obtaining the sine wave current corresponding to the rotor position is to be obtained.

FIG. 2 is a block diagram of the above-mentioned apparatus, in which 10 is a converter section, 20 is an inverter section, 30 is a control section, and 40 is a servomotor section.

In the converter unit 10, the voltage from the AC power source 11 is converted into a DC voltage by the rectifier 12 and the smoothing capacitor 13 removes ripples and supplies it as a power source for the next inverter unit 20.

The inverter section 20 is composed of a three-phase inverter 21 composed of transistors, a gate circuit 22 for supplying a control current to the transistors of the inverter 21, and a current control circuit (ACR) 23. The generated sine wave signal generates a three-phase sine wave current, which is supplied to the armature winding of the servo motor 41.

The rotor shaft of the servo motor 41 is fixed with (CS) 42 for detecting the magnetic pole position of the rotor and (EC) 43 for finely detecting the rotation angle of the rotor shaft. The output of EC) 43 is sent to the control unit 30, and the sine wave signal generation circuit
32 generates a sine wave signal corresponding to the rotor position,
It is sent to the current control circuit (ACR) 23 of the inverter unit 20.

FIG. 3 is a block diagram showing the configuration of the sine wave signal generation circuit 32 of the control unit 30, where 1 is the (CS) input terminal and 2, 3
Is an (EC) input terminal, 4 is an initial value setting circuit, 5 is a ring counter, 6 is a direction discriminating circuit for detecting the rotation direction from the output of (EC), 7 is a ROM storing sign data, and 8 is D / A
The converter 9 is an output terminal.

FIG. 4 is a waveform diagram showing voltage waveforms at various parts of the system shown in FIG. 2, where (a) is the induced voltage in the U, V, and W phase windings of the three-phase armature winding, and (b) is (CS ) U, V, W output voltage of each phase,
(C) is the digital signal level of the (CS) signal,
(D) is a pulse group of the output voltage of (EC), (e) is (EC)
, The output voltage waveforms of the A and B phases that are 90 ° out of phase with each other,
(F) shows the contents of the signature data stored in the ROM 7, respectively.

The contents of the ROM 7 are read by the output of the ring counter 5, and the contents of the ring counter 5 discriminate the output voltage of the A and B phases of (EC) by the direction discriminating circuit 6 to discriminate the rotation direction and determine the direction. It is updated by the up or down signal output in accordance with. Therefore, the sine waveform output corresponding to the minute angular displacement of the rotor shaft detected at (EC) is obtained from the ROM 7.

That is, the value output from the ring counter 5 for each output pulse of (EC) corresponds to the angle signal of the ROM 7, and the sine wave signal corresponding to this angle signal is output from the ROM 7.

However, in this device, since the output of ROM7 is obtained from the output of (EC), the position of the rotor shaft and the value of the ring counter 5 do not correspond normally in the initial state, and self-starting is not possible. There is.

However, as the (CS) signal, U, V,
Since the three-phase output of W can be obtained, the initial value setting circuit 4 is provided to detect the approximate position of the rotor shaft from the (CS) signal, and the output corresponding to this position is output from the ROM7 for self-starting. ing.

That is, each phase of U, V and W of (CS) signal is converted to 0, 1 of digital signal.
The level display changes every time the rotor rotates by 60 degrees as shown in FIG. 4 (c).

In this way, regardless of the position of the rotor, the 0,1 signals shown in Fig. 4 (c) are generated by the combination of (CS) signals, and the signal changes every time the rotor rotates 60 degrees. Because
The rotor position can be detected every 60 degrees.

When the output of the initial value setting circuit 4 is input to the ring counter 5 and preset, an output corresponding to the approximate position of the rotor is output from the ring counter 5, and the angle is output from the ROM 7 via the D / A converter 8. The corresponding sine wave signal is output.

Servo motor 41 is started by the current of this initial value,
The value of the ring counter 5 is set to the normal relationship with the rotor position at the switching position of the (CS) signal, and thereafter, the contents of the ring counter 5 are updated with the output of (EC), and the angle corresponding to the resolution of (EC) is set. The value according to the position is output from ROM7, and D /
It is converted into a sine wave signal through the A converter 8 and converted into a current by the current control circuit 23, which controls the gate circuit 22 so that the sine wave current is supplied to the armature winding of the servo motor 41 through the inverter 21. Supplied.

(Problems to be Solved by the Invention) However, in the conventional sine wave signal generating circuit shown in FIG. 3, the content of the ring counter 5 is updated by the output pulse signal of (EC). There is a constraint that the number of digits of the ring counter 5 must match the number of (EC) pulses.

For this reason, if the number of pulses of (EC) is changed, the number of digits of the ring counter 5 must be changed, but it is difficult to configure the ring counter 5 having an arbitrary number of digits.

Further, if the count value of the counter may deviate, this correction cannot be performed, and the structure of the initial value setting circuit 4 is complicated.

(2) Configuration of the Invention (Means for Solving the Problems) The sine wave signal generator for the brushless motor of the present invention does not need to change the counter even if the number of (EC) pulses changes, and is simple. It is possible to reduce the number of digits of the counter as well as.

A sine wave signal generator for a brushless motor according to the present invention is a brushless device having a rotor having a field and an armature having three-phase windings arranged through the air gap with the rotor. The output of the magnetic pole position detection device provided coaxially with the rotor of the motor is added to the ROM storing the sign data and added to the ROM.
In addition to setting the read area of the sign data stored in, the output setting terminal of the up / down counter and the up / down counter are connected via the first direction discrimination circuit.
When the motor is rotating in the forward direction, it is set to the minimum, and when it is rotating in the reverse direction, it is set to the maximum, and the output of the encoder provided coaxially with the rotor is set to the input of the up / down counter via the second direction discrimination circuit. In addition to the terminals, the contents of the up / down counter are increased from the minimum when the motor is in the forward rotation and decreased from the maximum when the motor is in the reverse rotation, and the output of the up / down counter is input to the ROM that stores the sign data.
It is characterized in that a sine wave signal corresponding to the rotor position is further extracted.

(Operation) The sine wave signal generator for the brushless motor of the present invention reads the sine data from the ROM in which the sine data is stored, and is controlled by the (CS) signal and the (EC) signal. Since the output of the down counter is used, it is not necessary to match the number of output pulses of (EC) with the number of digits of the counter. Changing the number of (EC) pulses often changes the counter only by changing the contents of ROM. No need.

(Embodiment) In the sine wave signal generator for the brushless motor of the present invention, as shown in FIG. 1, (CS) signals U, V and W are converted into (C
The rotor position is changed every 60 degrees even after the power is turned on, even if the servo motor 41 is not rotating immediately after the power is turned on, which is input to the first direction discriminating circuit 51 that determines the rotation direction of S). Then, the read area of the signature data stored in the ROM is set by this data.

Further, the up / down counter 53 outputs the up or down signal output depending on the rotation direction obtained from the first direction discrimination circuit 51.
In addition to the clear setting terminal CLR and the output setting terminal of the preset terminal L0, it is set to the minimum when the motor rotates in the forward direction and set to the maximum when it rotates in the reverse direction.

Further, (EC) A-phase and B-phase output signals having mutually different 90 ° phases are input to the second direction discriminating circuit 52, and the up or down signal output depending on the rotation direction is up-down counter 53.
In addition, the contents of the up / down counter 53 change from the minimum to the maximum when the motor rotates forward and decrease from the maximum when the motor reverses.The output of the up / down counter 53 is stored in the ROM 54 that stores the signature data. So that the sine waveform output corresponding to the output data of the up / down counter 53 can be obtained from the ROM 54.

Since the sine wave signal generator for the brushless motor of the present invention has the above-mentioned configuration, the sign data stored in the area designated by the (CS) of the ROM 54 has the number of pulses generated at (EC). Correspondingly read data can be converted into a voltage via the D / A converter 55 and sent to the current control circuit 23 to form a sine wave current to start the servo motor 41.

That is, for example, in the waveform diagrams of the armature voltage and the (CS) signal shown in FIGS. 4 (a) and 4 (b), if the power is turned on at time t = 0, the data obtained from the (CS) signal Is U = 0, V = 0, W = 1, and ROM5 corresponding to this data
The output of 4 is sent to the D / A converter 55 and the servo motor
When 41 starts up and rotates to the right in the figure, and the U phase of the (CS) signal changes from U = 0 to U = 1, a reset signal is sent to the up / down counter 53 and the address data of ROM 54 is sent. The output corresponding to each position of the U-phase angle is 0 degree, the V-phase angle is −120 degrees, and the W-phase angle is +120 degrees. The reference of rotor position and the reference content of ROM54 And match.

Next, when the servo motor 41 is rotating in the forward direction, the up / down counter 53 inputs the counter 53 from the position of sin0 degree.
An output that changes with each output pulse is obtained on the data bus.

When the rotation of the servo motor 41 is reversed, the output phase of the up / down counter 53 is reversed, the direction of scanning the contents of the ROM 54 is reversed, and the phase rotation direction of the output is reversed to respond.

The content of the up / down counter 53 is reset every time the up / down signal sent from the first direction discriminating circuit 51 changes, and as described above, the content changes according to the rotation direction.
It operates to be set to the minimum or maximum, and the number of digits of the up / down counter 53 is set to be at least twice the number of pulses input between the first reset and the next reset. Even if a miscount occurs in the middle, the error is not accumulated because it is always reset every time the (CS) signal changes.

In addition, since the (CS) U, V, W phase signals are input to the ROM that stores the sign data, the up / down counter 53
Even if the output of and the positional relationship of the rotor is not normal,
The output data of the U-phase, V-phase, and W-phase is output through the D / A converter 55 as data corresponding to any position of the angle that changes every 60 degrees, and the servo motor can be activated.

(Effects of the Invention) The sine wave signal generator for the brushless motor of the present invention has the following effects.

(1) The number of digits of the up / down counter may be set to a number larger than twice the number of pulses to the up / down counter, which is made from the number of encoder pulses obtained within the angle divided by the (CS) signal. The configuration is easy because it can be set regardless of the number of pulses of the encoder.

(2) To change the number of encoder pulses, the contents of the ROM that stores the sine data can be changed according to the number of encoder pulses, and no hardware change is required.

(3) Even if the contents of the counter deviate, it is reset every time the (CS) signal changes, so it is possible to generate a highly accurate sine wave signal without accumulating errors. Yes, a highly accurate brushless motor controller can be configured.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a circuit diagram of a sine wave signal generator for a brushless motor according to the present invention, FIG. 2 is a block diagram of a sine wave signal generator for a conventional brushless motor, and FIG. FIG. 4 is a block diagram of a sine wave signal generating circuit according to the prior art, and FIGS. 4 (a) to 4 (f) are diagrams showing signals of respective parts thereof. 1 ...... Commutation sensor (CS) input terminals, 2, 3 ...
… Encoder (EC) input terminal, 4 …… Initial value setting circuit, 5 …… Ring counter, 6,51,52 …… Direction discrimination circuit, 7,54 …… ROM, 8,55 …… D / A converter , 9 …… Output terminal, 10 …… Converter, 11 …… Power supply, 12 …… Rectifier, 13 …… Smoothing capacitor, 21 …… Inverter, 22 ……
Gate circuit, 23 ... Current control circuit (ACR), 30 ... Control section, 32 ... Sine wave signal generation circuit, 40 ... Servo motor section, 41 ... Servo motor, 42 ... Commutation sensor (CS) , 43 …… Encoder ((EC), 53 …… Up / Down counter, 56,57 …… OR gate.

Claims (1)

(57) [Claims] 1. A brushless motor having a rotor provided with a field and an armature provided with a winding of three phases arranged with a gap between the rotor and the rotor provided coaxially with the rotor. The output of the magnetic pole position detector is set in addition to the ROM storing the sign data and the read area of the sign data stored in the ROM is set, and is also added to the output setting terminal of the up / down counter via the first direction discrimination circuit. , The up-down counter is set to the minimum when the motor is in the forward rotation, and is set to the maximum when the motor is in the reverse rotation, and the output of the encoder provided coaxially with the rotor is output via the second direction discrimination circuit. In addition to the input setting terminals of the up / down counter, the contents of the up / down counter are increased from the minimum when the motor is in forward rotation and decreased from the maximum when the motor is in reverse rotation. Sine wave signal generating apparatus for a brushless motor, characterized in that they were taken out of the sine wave signal corresponding to the rotor position from the ROM is input to the ROM which stores in data.