JPS6130477Y2 - - Google Patents

Description

[Detailed description of the invention] [Description of the field to which the invention pertains] The present invention relates to a drive device for a permanent magnet rotor type brushless motor.

[Description of conventional technology]

In a brushless motor, in order to generate torque T _M , it is necessary to generate a rotating magnetic field by passing currents that are out of phase with each other through the windings of each phase. In a permanent magnet rotor type two-phase brushless motor, α
By flowing currents i〓, i〓 through the phase and β phase, T
A torque of _M = K _e (i〓sinθ+i〓cosθ) can be obtained. Here, K _e is a constant determined by the motor configuration method and material effect characteristics, and θ is the rotation angle (relative electrical angle between the stator magnetic axis and the rotor magnetic axis). Therefore, if a current is passed according to the rotation angle θ so that i = i sin θ (1) i = i cos θ (2), this output torque T _M will be constant at any point of the rotation angle. It is known that a torque K _e i can be obtained. That is, in order to obtain a constant torque in this brushless motor, signals of the product of the sine and cosine of the rotation angle and the amount of current i that defines the magnitude of torque are required for the α and β phases.

Conventionally, in this type of device, for example, a device called a resolver is used to generate analog signals that are the sine and cosine quantities of the rotation angle, and these sine and cosine signals are combined with the current value that specifies the magnitude of the torque. Product α
A method of driving the phase and β phase is used. However, when a resolver is used, torque ripples of harmonic components occur due to waveform distortion of trigonometric functions due to the limits of the resolver's processing accuracy, making it difficult to downsize the resolver, and using a brushless electric motor for positioning control. In this case, a dual position detector such as a positioning detector and a resolver is required, and an efficient servo drive system cannot be configured.

[Purpose of invention]

In order to eliminate the drawbacks of the conventional example, the present invention converts the angle signal from the digital position detector into a signal that reciprocates between two given values using an up-down counter circuit, and converts this signal into a non-linear digital-to-analog converter. The present invention provides a brushless motor drive device that uses a device to generate trigonometric functions corresponding to each phase. Hereinafter, embodiments will be described in detail with reference to the drawings.

[Explanation of the structure and function of the device]

Figure 1 shows an embodiment of the drive device for a brushless motor according to the present invention.
An example of application to a phase brushless motor is shown. In the figure, 1 is a brushless motor, 2 is a rotor of the brushless motor 1, 3a and 3b are α-phase and β-phase windings of the brushless motor 1, 4 is a digital position detector, 5 is the output of the digital position detector 4, 6a and 6b are up-down counter circuits; 7
a, 7b are up-down counter circuits 6a, 6b
outputs, 8a and 8b are nonlinear digital-to-analog converters, 9a and 9b are outputs from nonlinear digital-to-analog converters 8a and 8b, 10 is a torque command input, 11a and 11b are analog multipliers, 12a,
12b is the α-phase and β-phase drive signal; 13a, 1
3b is a current-controlled power amplifier, 14a and 14b are α-phase and β-phase drive currents, and θ is a rotation angle, with clockwise rotation being positive.

Next, the operation of this embodiment will be explained. First, the rotor 2 of the brushless motor 1 obtains rotational force by passing sinusoidal currents having a phase difference of 90 degrees to each other through the α-phase winding 3a and the β-phase winding 3b. The output 5 of the digital position detector 4 directly connected to the rotor 2 is an up-down counter circuit 6a, 6b for each phase.
The up-down counter circuits 6a and 6b detect the rotation direction and count up or down the contents of each counter circuit set in advance. The contents become outputs 7a and 7b of each counter circuit, and are converted into analog quantities by nonlinear digital-to-analog converters 8a and 8b. Here, up-down counter circuits 6a and 6b and a nonlinear digital-to-analog converter 8
The characteristics of a and 8b are set so that the outputs 9a and 9b are trigonometric functions of the rotor angle θ with a phase difference of 90°. Next, the outputs 9a, 9b of the nonlinear digital-to-analog converters 8a, 8b are multiplied by the torque command input 10 by analog multipliers 11a, 11b, and the α-phase and β-phase drive signals 12a, 1
It becomes 2b. The drive signals 12a, 12b supply sinusoidal currents 14a, 14b with a phase shift of 90° to the α-phase and β-phase windings 3a, 3b, respectively, by current-controlled power amplifiers 13a, 13b.

FIG. 2 shows an example of the circuit configuration of the up-down counter circuits 6a and 6b in the embodiment shown in FIG. Between (n-
A case will be explained in which a digital position detector that outputs m) (n>m) pulses is used. In FIG. 2, 5 is the output of the digital position detector 4, 7 is the output of the up-down counter circuit, and 15 is the output of the up-down counter circuit.
16 is the output of the logic circuit 15, 17 is the matching circuit, 18 is the output of the matching circuit 17, 19 is the up/down counter, and 20 is the logic circuit that detects the phase difference of the pulses and determines the rotation direction. 21 is a matching circuit that becomes logic 1 only when the input is m, 22 is a data selector, 2
3 is a set-reset flip-flop, and 24 is an output of the set-reset flip-flop 23.

Next, the operation of this circuit will be explained. First, when the rotor angle .theta. is 0, the contents of the up-down counter 19 are set to (n+m)/2 and the output 24 of the reset flip-flop 23 is set to logic 1. The rotation direction determination logic circuit 15 detects the phase difference of the output 5 of the digital position detector, so that when the rotor angle θ moves in the positive direction, its output 16 becomes logic 1. In this case, the output 18 of the matching circuit 17 becomes a logic 1, and the up-down counter 19 performs up-counting. and its value is n
, the output of the matching circuit 20 becomes logic 1.
The reset flip-flop 23 is set through the data selector 22, and its output 24 becomes logic 0. Therefore, the output of the coincidence circuit 17 becomes logic 0, and the up/down counter 19 starts counting down. When the output 7 of this up-down counter 19 becomes equal to m,
The output of match circuit 21 becomes a logic 1 and resets the reset flip-flop 23 through the data selector 22, whose output 24 becomes a logic 1. Therefore, the output 7 of the up-down counter 19
goes back and forth between n and m. If the rotor angle moves in the negative direction, the same explanation can be given, only the function of the data selector 22 is reversed.

FIG. 3 shows the circuit configuration of a portion related to the nonlinear digital-to-analog converters 8a and 8b in the embodiment shown in FIG. Similarly, it consists of ROM and a normal digital-to-analog converter. In Figure 3,
The same symbols as in FIG. 1 represent the same functional parts, 8
1a and 81b are ROMs, 82a and 82b are digital-to-analog converters, and 60 is a set pulse input (not shown in FIG. 1). Here, the set pulse 60 may be the origin pulse (zero marker pulse) of the digital position detector 4, and is used to set the counter value of the counter circuit 6a to A and the counter value of the counter circuit 6b to B, as described above. , for example, the α-phase magnetic axis is more electrically
If it moves 90 degrees, A=n, B=(m+n/
It can be set as 2. Also, ROM81
Contents as shown in FIG. 4 are stored in a and 81b, and a nonlinear output is sent out in response to an input signal.

Next, the nonlinear digital-to-analog converter 8a,
The operation of 8b will be explained in the case where the input, ie, the output of the up-down counter, goes back and forth between n and m. For example, when the output of the up-down counter is x, the output of the converter is a sin
If weighting is performed so that {π/n−m(x−n+m/2)}, the output can obtain a value proportional to sinθ. Also, the same thing can be done when the phase differs by 90 degrees.

As mentioned above, an example of a brushless motor drive system using an up-down circuit and a nonlinear digital-to-analog converter has been explained using a two-phase brushless motor as an example. Either generate an approximate trigonometric function using a nonlinear digital-to-analog converter, or create a two-phase approximate trigonometric function, multiply this two-phase approximate trigonometric function by the torque command input, and apply the two-phase multiplication result to the electrical machine of each phase. By combining the multiphase signals corresponding to the child windings, the two-phase driving method can be extended to the multiphase case.

[Explanation of effects]

As explained above, the present invention uses a counter circuit to convert a digital position signal into a signal that reciprocates between two given values, and a nonlinear digital-to-analog converter converts the digital position signal into a signal that reciprocates between two given values. Since this is a brushless motor drive device that generates a drive signal of It is possible to achieve the following servo characteristics.

In addition, in this invention, the digital position detector is used both as a detector for positioning control of the servo motor and for detecting the position of the drive rotor, so the load on the servo motor can be reduced and the servo motor can be made smaller and lighter. There are advantages.

[Brief explanation of the drawing]

FIG. 1 is a block diagram for explaining an embodiment of a drive device for a brushless motor according to the present invention, and FIG. 2 is a diagram showing an example of the up-down counter circuit configuration in the embodiment of FIG. 3 is a diagram showing an example of the configuration of a portion related to the nonlinear digital-to-analog converter in the embodiment of FIG. 1, and FIG. 4 is a diagram explaining the contents of the ROM in FIG. 3. 1...Brushless electric motor, 2...Rotor, 3
a, 3b...α phase, β phase winding, 4...Digital position detector, 5...Digital position detector output,
6a, 6b...Up-down counter circuit, 7
a, 7b...Up-down counter circuit output, 8
a, 8b...nonlinear digital-to-analog converter,
9a, 9b...Nonlinear digital analog converter output, 10...Torque command input, 11a, 11b
...Analog multiplier, 12a, 12b...α phase,
β phase drive signal, 13a, 13b...Current control type power amplifier, 14a, 14b...α phase, β phase drive current, 15...Direction discrimination logic circuit, 16...Direction discrimination logic circuit output, 17... ... Matching circuit, 18... Matching circuit output, 19... Up-down counter, 2
0, 21... Matching circuit, 22... Data selector, 23... Set reset flip-flop,
24...Set reset flip-flop output,
60...Set pulse input, 81a, 81b...
ROM, 82a, 82b...digital analog converter.

Claims (1)

[Claims for Utility Model Registration] A digital position detector for detecting the rotational position of a rotor of a brushless electric motor, and a digital position detector that counts the pulses of the digital position detector and calculates the relative electricity generated by the rotor magnetic axis with respect to the stator magnetic axis. an up-down counter circuit that outputs a digital signal representing an angle; a nonlinear digital-to-analog converter that converts the relative electrical angle signal output from the up-down counter circuit into an analog signal representing a trigonometric function of the relative electrical angle; an analog multiplier that calculates the product of a torque command input that defines the magnitude of torque and an analog signal representing the trigonometric function; and a stator winding with a current proportional to the result of the product operation output from the analog multiplier. A drive circuit for a brushless motor, comprising: a drive circuit for driving the up-down counter circuit; a rotation direction determination circuit for detecting the phase of the pulse of the digital position detector to determine the rotation direction of the rotor; A brushless electric motor comprising: an up-down counter that counts output pulses of a rotation direction discrimination circuit; and a logic circuit that controls the output of the up-down counter so that it reciprocates between two given values. Drive device.