JP2687651B2 - Disconnection detection circuit for magnetic resolver - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Field of Industrial Application> The present invention relates to an improvement in a disconnection detection circuit of a phase modulation type magnetic resolver.

<Prior Art> Conventionally, as a disconnection detection circuit for such a magnetic resolver, for example, there is a configuration shown in FIG.

In the figure, 1 is a magnetic resolver and 2 is a disconnection detection circuit.

The magnetic resolver 1 includes a resolver unit 11, an exciting circuit 12,
And a phase detection circuit 13.

The resolver unit 11 is described in the application specification of Japanese Patent Application No. 63-218892 by the present applicant.

In the resolver unit 11, 111 to 114 are coils wound around salient poles of the rotor. The stator of the resolver unit 11 has a mechanical angle of 90 degrees.
Salient poles are formed at positions different by 0 °, and coils 111, 112, 113, 114 are wound around the salient poles at 0 ° position, 90 ° position, 180 ° position, and 270 ° position, respectively. The teeth of pitch P are formed at the tip of each salient pole,
The salient pole teeth at the ° position, 180 ° position, and 270 ° position have a phase of 0, (1/4) P, (2/4) P, (3/4) with respect to the reference position, respectively.
It is shifted by P. Reference numeral 115 denotes a rotor, which rotates together with a rotation detection target such as a motor. Teeth are formed at a pitch P on the rotor 115 at positions facing the teeth of the salient poles of the stator. CN1 to CN6 are connectors for connecting each coil.

In the exciting circuit 12, 121 is a signal source for exciting the coils 111 and 113 with an AC voltage (E is the amplitude of the voltage, ω is the angular velocity, and t is time) of Esinωt, and 122 is an AC voltage of the coils 112 and 114 that is Ecosωt It is a signal source that excites.

In the phase detection circuit 13, R ₁ , R ₂ , R ₃ , and R ₄ are coils 111, 11
Currents I ₁ , I ₂ , I ₃ , and I ₄ flowing through 3,112,114 are respectively applied to voltage V
These are resistors that convert to ₁ , V ₂ , V ₃ , and V ₄ . 131 is a subtractor that takes the difference between V ₁ and V ₂ , 132 is a subtractor that takes the difference between V ₃ and V ₄ , 133 is 2
It is an adder that adds the difference signals V _a and V _b of two subtractors. This addition signal V _c becomes the rotation detection signal of the motor.

In the disconnection detection circuit 2, 21 is an amplitude level detection circuit for detecting the amplitude of the detection signal V _c , and 22 is the detected amplitude level as a reference value.
If it is lower than V _REF1 , it is the amplitude level abnormal drop detection circuit that generates the abnormal detection signal ER1.

In this circuit, when there is no break in any of the connector CN1~CN6, the voltage V ₁ ~V ₄ is given by the following equation.

V ₁ = a {1+ (m / 2) cosψ} × sinωt V ₂ = a {1- (m / 2) cosψ} × sinωt V ₃ = a {1+ (m / 2) sinψ} × cosωt V ₄ = a {1- (m / 2) sin ψ} × cos ωt a: constant, m: constant (<< 1) ψ: rotation angle of rotor Based on these voltages, the phase detection circuit 13 calculates the following equation, A phase-modulated detection signal V _c is obtained.

V _c = V ₁ −V ₂ + V ₃ −V ₄ = amsin (ωt + ψ) The amplitude level detection circuit 21 detects the amplitude am of V _c . Here, since am> V _REF1 , the amplitude level abnormal drop detection circuit 22 generates a signal indicating no abnormality.

<Problems to be solved by the invention> However, if only the connector CN3 is disconnected, m
From << 1, the detection signal V _c is given by the following equation.

V _c = −V ₂ + V ₃ −V ₄ = −a {1- (m / 2) cos ψ} × sin ωt + amsin ψcos ωt ≈−a cos ψsinωt From this detection signal V _c , the amplitude level detection circuit 21 outputs the amplitude a.
Is detected. Here, since a> am and a> V _REF1 , the amplitude level abnormal drop detection circuit 22 generates a signal indicating no abnormality.

From this, the disconnection is not detected although the disconnection actually occurs.

The cable of the magnetic resolver may be disconnected due to connection mistakes at the customer, defective soldering, bending of the cable, or the like.

If a false signal unrelated to the original detection signal of the magnetic resolver is sent to the motor control circuit due to the disconnection, the motor will also run away.

The present invention has been made in order to solve such a problem, and an object thereof is to realize a disconnection detection circuit of a magnetic resolver capable of detecting an abnormality in any combination of disconnections.

<Means for Solving the Problems> According to the present invention, a rotor in which teeth are formed at a pitch P and salient poles are provided at positions where mechanical angles differ by 90 °, and the salient poles have the above-mentioned tips at their tips. A rotor formed with teeth having a pitch P facing the teeth of the rotor, a salient pole located at a mechanical angle of 0 ° and a coil wound around a salient pole located at a 180 ° mechanical angle are excited by a sin phase AC signal, The difference between the signal source that excites the coil wound around the salient pole at the 90 ° position and the coil at the 270 ° position with the AC signal of the cos phase and the difference between the currents flowing in the coil excited with the AC signal of the sin phase , A calculation unit that adds a difference between currents flowing in coils excited by an AC signal of a cos phase and calculates a phase modulation signal whose phase changes 360 ° when the rotor makes one rotation. An amplitude level detection circuit for detecting the amplitude of the phase modulation signal, and an amplitude level detection circuit A disconnection signal is generated when the detection amplitude of the circuit detection circuit is smaller than a predetermined reference value, and this reference value is set to a value smaller than the amplitude of the phase modulation signal when there is no disconnection in the connection wire of each coil. And an amplitude level abnormal drop detection circuit, which generates a disconnection signal when the detected amplitude of the amplitude detection circuit is larger than a predetermined reference value, and the reference value is when there is no disconnection in the connection line of each coil. The disconnection detection circuit for a magnetic resolver, comprising: an abnormal amplitude level rise detection circuit set to a value larger than the amplitude of the phase-modulated signal.

<Operation> In the present invention as described above, all possible combinations of wire breakages are detected in both the circuit for detecting an abnormal rise in the amplitude of the detection signal of the magnetic resolver and the circuit for detecting an abnormal fall.

<Example> Hereinafter, the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram of an embodiment of a disconnection detection circuit for a magnetic resolver according to the present invention. The same parts as those in FIG. 4 are designated by the same reference numerals in FIG.

In FIG. 1, reference numeral 3 denotes an amplitude level abnormally rising circuit which is a feature of the present invention. When the detected amplitude V _d of the amplitude level detection circuit 21 is higher than the reference value V _REF2 , the abnormal signal ER2
Occurs.

The reference values V _REF1 and V _REF2 are set to the following magnitudes.

0 <V _REF1 <am <V _REF2 <a Combination of disconnection and detection amplitude V _d of amplitude level detection circuit 21
The relationship of is shown in FIG. As shown in this figure, the detected amplitude
V _d is one of 0.amsin ψ, ancos ψ, a, √2a. The magnitude relationship between the detected amplitude and the reference value is shown in a graph of FIG.

From the condition of | amsinψ | ≧ V _REF1 , and | amcosψ | ≧ V
Disconnection can be detected except in the case of _REF1 .

Considering that the motor rotates, in reality it is always | a.
Since msin ψ | ≧ V _REF1 and | amcos ψ | ≧ V _REF1 do not hold, practically, disconnection can be detected in all cases.

<Effect> According to the present invention, since the disconnection is detected from both the abnormal decrease and the abnormal increase in the amplitude of the detection signal of the magnetic resolver,
It is possible to detect all combinations of breaks in the magnetic resolver that may occur in practice.

[Brief description of the drawings]

FIG. 1 is a block diagram of one embodiment of the present invention, and FIGS.
FIG. 4 is a diagram for explaining the operation of the circuit of FIG. 1, and FIG. 4 is a diagram showing a configuration example of a conventional disconnection detection circuit for a magnetic resolver. 1 ... Magnetic resolver, 11 ... Resolver section, 12 ... Excitation circuit, 13 ... Phase detection circuit, 2 ... Disconnection detection circuit, 21 ...
Amplitude level detection circuit, 22 ...... Amplitude level abnormal drop detection circuit, 3 ... Amplitude level abnormal rise detection circuit.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical indication H02P 5/00 H02P 5/00 T

Claims (1)

(57) [Claims] 1. A rotor having teeth formed at a pitch P, and salient poles are provided at positions where mechanical angles differ by 90 °, and a pitch P facing the teeth of the rotor is provided at the tip of each salient pole. The rotor with the teeth of, the coil wound around the salient pole at 0 ° mechanical position and the salient pole at 180 ° mechanical angle are excited by the sin phase AC signal, and the salient pole at 90 ° Coil the coil wound around the salient pole at the 270 ° position.
Add the difference between the currents flowing in the coil excited by the os-phase AC signal and the coil excited by the sin-phase AC signal, and the difference between the currents flowing in the coils excited by the cos-phase AC signal, An amplitude level detection circuit for detecting the amplitude of the phase modulation signal, the amplitude level detection circuit being applied to a magnetic resolver having a calculation unit that calculates a phase modulation signal whose phase changes 360 ° when the rotor makes one rotation. A disconnection signal is generated when the detected amplitude of is smaller than a predetermined reference value, and this reference value is set to a value smaller than the amplitude of the phase modulation signal when there is no disconnection in the connection line of each coil. An amplitude level abnormal drop detection circuit and a disconnection signal are generated when the detected amplitude of the amplitude detection circuit is larger than a predetermined reference value, and the reference value is phase modulation when there is no disconnection in the connection line of each coil. Belief Amplitude level abnormal increase detection circuit, disconnection detection circuit of a magnetic resolver, characterized by comprising a that is set to a value larger than the amplitude of the.