JP3328999B2 - Absolute position detector - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a resolver for detecting an absolute position used in an industrial robot or the like, and more particularly to a resolver for backing up when a power failure occurs. [0002]

2. Description of the Related Art Conventionally, an absolute position detector such as a resolver is connected to a rotating shaft of an actuator for driving an arm of an articulated robot or the like, and the amount of rotation is detected. There is a method of obtaining an absolute position by a resolver even at the time of a power failure to obtain the position. When the exciting coil of the resolver is excited with a sine wave, the oscillator outputs a sine wave signal, and the excitation amplifier that amplifies the sine wave signal also outputs a sine wave exciting current (first conventional technique). There is also a method of switching the excitation method from a sine wave excitation method to a pulse wave excitation method at the time of energization and at the time of a power failure (second prior art, for example, JP-A-63-214617).

[0003]

In the first prior art, the power consumption of the sine wave oscillator and the excitation amplifier is large. In particular, since a sine wave oscillator requires a large number of operational amplifiers, power consumption cannot be reduced. When a backup is performed using a battery or the like at the time of a power failure, the battery is significantly consumed. Further, the second prior art has a problem that the circuit is complicated and the cost is high. The present invention relates to the absolute position detection, which has both the excitation circuit that always realizes low power consumption by the sine wave excitation method without switching the excitation method at the time of energization and power failure, and the detection circuit that consumes less power at the time of power failure. The purpose is to provide a vessel.

[0004]

The present invention provides a one-phase excitation coil.
Rotor with a rotor and two phases with 90 ° phase difference
A stator provided with an output coil and exciting the exciting coil
Excitation circuit and angle detection for detecting the rotation angle of the rotor
And a rotation amount storage circuit for detecting and counting the rotation amount,
Power detector to detect whether the power
Battery for backing up the circuit and the rotation amount storage circuit
An absolute position detector comprising:
Sine the square wave generated by the square wave oscillator with the filter circuit
The excitation frequency of the excitation circuit.
The excitation voltage and frequency settings are set so that the power failure is greater than when the power is on.
A switch is provided.

[0005]

The excitation circuit replaces the conventional sine wave oscillator, amplifies the square wave signal of the square wave oscillator through an amplifier, converts the output of the amplifier into a sine wave through a filter, and excites the excitation coil. The circuit that detects the rotation angle and rotation amount is
At the time of energization, the rotation angle and the rotation amount are detected, and at the time of power failure, only the rotation amount is detected. Power is always supplied to the backup area (detection circuit, excitation circuit, resolver) even when power is supplied or during a power failure. Further, the amplitude of the excitation voltage of the excitation circuit during power outage is smaller than during energization, the excitation frequency of the excitation circuit is higher during power outage than during energization, the excitation frequency of the excitation circuit during power outage, and the rotor Is changed according to the operation during the operation. As a result, the consumption of the backup battery is suppressed.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described based on an embodiment shown in the drawings. FIG. 1 is a block diagram showing the entire circuit configuration. A resolver (A) is fixed to a rotation shaft to be detected and has a rotor provided with a one-phase excitation coil (A-1), and a 90 ° phase in electrical angle with each other. And a stator provided with two-phase detection coils (B-1, B-2) different from each other. The exciting circuit (M) for exciting the exciting coil includes a square wave oscillator (J), a buffer amplifier (I),
The square wave output from the buffer amplifier, which is composed of an L / C filter (H), has its harmonics removed by the L / C filter, is converted into a sine wave, and is supplied to the exciting coil of the resolver. FIG. 2 is a block diagram showing the excitation circuit of the embodiment. During a power outage, power is supplied only to the backup area. Only the multiple rotations of the motor (resolver) are backed up by the battery (L). Since there is no need to know the position within one rotation during a power failure, the R / D converter is not backed up. After power recovery, only the output signal of the R / D converter (position within one rotation) and the amount of multiple rotations are stored in memory.
The signal of the rotating amount storage circuit is input to a controller (G) to detect the absolute position of a motor (resolver). The excitation voltage and frequency setting are switched by detection signals from an energization detector (N) for detecting whether a commercial power supply (not shown) is energized or a power failure and an operation detector (P) for detecting the operation of the rotor. The gain of the buffer amplifier is reduced through the switch (Q) so that the amplitude of the excitation voltage of the excitation circuit is smaller than that during energization, or the excitation frequency of the excitation circuit is set to be greater than during energization. The input impedance of the excitation circuit.
By increasing the dance, the excitation current can be reduced, or the excitation frequency can be changed in response to a signal from the operation detector when the rotor is operating due to inertia during a power outage. This can further reduce the consumption of the backup battery. The rotation amount is detected in the following procedure. A detection signal generated from the detection coil is input to a synchronous rectifier circuit (C), and an output signal of the synchronous rectifier circuit is sent to a rotation amount storage circuit (E) through a comparator (D).
It is counted and stored. The rotation angle is detected by the R / D
The conversion is performed by the converter (F). When a power failure signal is received, power is supplied only to the backup area (K) and the R / D
The converter does not work.

[0007]

According to the present invention, a sine wave is generated by the square wave oscillator and the filter without using the sine wave oscillator, so that power consumption can be reduced without switching between energization and power failure, and the circuit is simple. Cost reduction can be achieved.

[Brief description of the drawings]

FIG. 1 is a block diagram showing the entire circuit configuration of an embodiment of the present invention.

FIG. 2 is a block diagram illustrating an excitation circuit according to an embodiment of the present invention.

[Explanation of symbols]

 (A) Resolver (A-1) Excitation coil (B-1), (B-2) Detection coil (C) Synchronous rectifier circuit (D) Comparator, (E) Rotation amount storage circuit (F) R / D converter ( G) controller, (H) L / C filter (I) buffer amplifier (J) square wave oscillator, (K) backup area (L) battery (M) excitation circuit (N) conduction detector (P) operation detector ( Q) Excitation voltage / frequency setting switch

──────────────────────────────────────────────────の Continued on the front page Examiner Masahiro Inoue (56) References JP-A-5-5629 (JP, A) JP-A-1-272914 (JP, A) JP-A 63-172913 (JP, U) Kaihei 1-25707 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) G01D 5/00-5/62 G01B ⁷ /00-7/34

Claims (1)

(57) [Claims] A rotor provided with a one-phase excitation coil;
° A stator having two-phase detection coils having different phases,
An exciting circuit for exciting the exciting coil;
An angle detector that detects the rotation angle, and a rotation amount that is detected and counted.
Rotation amount storage circuit and energization detection to detect energization or power failure
The excitation circuit and the rotation amount storage circuit in the event of a power failure.
Absolute position detector with backup battery
And the excitation circuit filters a square wave generated by the square wave oscillator.
A sine wave excitation circuit with a filter circuit, and the excitation frequency of the excitation circuit is set to be greater during a power failure than during energization.
Excitation voltage / frequency setting switch
Absolute position detector.