JPH0716310B2 - Electromagnetic drive speed signal detector - Google Patents

Description

The present invention relates to a speed signal detection device for an electromagnetic drive device such as a servo motor.

[Conventional technology]

Conventionally, as a speed signal detection device for an electromagnetic drive device, a drive coil and a speed detection coil of the electromagnetic drive device are the same as disclosed in Japanese Patent Laid-Open No. 59-156139.

In the speed signal detection device of this electromagnetic drive device, as shown in FIG. 7, a drive current detection resistor 2 is connected in series with a drive coil 1 of the electromagnetic drive device, and the drive coil 1 and the drive current detection resistor 2 are connected to each other. An R / C integrating circuit composed of a series circuit of a resistor 3 and a capacitor 4 is connected in parallel with the / R integrating circuit. Then, the drive coil 1 is driven by the drive circuit 5 according to the input voltage, and the arithmetic circuit 6 calculates the difference between the output voltage A of the L / R integration circuit and the output voltage B of the R / C integration circuit to calculate the speed. Signal is required.

The speed signal detection device of the electromagnetic drive device is used in a speed control circuit or the like for controlling the speed of the electromagnetic drive device. The speed control circuit or the like controls the speed of the electromagnetic drive device based on the speed signal from the arithmetic circuit 6. I do.

[Problems to be Solved by the Invention]

In the speed signal detecting device of the electromagnetic drive device, the calculating circuit 6 calculates the difference between the output voltage A of the L / R integrating circuit and the output voltage B of the R / C integrating circuit to obtain the speed signal. The / R integration circuit does not become a primary integration system due to eddy current loss, hysteresis loss, etc., but becomes an integration system of about 0.9th order, so the drive coil of the electromagnetic drive device is forcibly fixed and the drive current is input to the drive coil. At this time, the difference between the output voltage A of the L / R integration circuit and the output voltage B of the R / C integration circuit does not become zero.
Therefore, the drive signal of the drive coil 1 is mixed in the speed signal from the arithmetic circuit 6, and the S / N is deteriorated. The deterioration of the S / N of the speed signal in this way means that the speed control band becomes narrower when the speed signal detection device of this electromagnetic drive is used in the speed control circuit to control the speed of the electromagnetic drive. I will end up.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a speed signal detecting device for an electromagnetic drive device, which can solve the above-mentioned drawbacks and can obtain a speed signal with a high S / N.

[Means for Solving the Problems]

In order to achieve the above object, the present invention is a speed signal detection device for an electromagnetic drive device that detects a speed signal of a drive coil 12 driven by a drive circuit 11, as shown in FIG. First A / D conversion means 13 for analog / digital converting the drive voltage Vi (t), and the drive coil 12
Drive current detection resistor 14 connected in series with the second, A / D conversion means 15 for analog / digital conversion of the voltage Vs (t) of the drive current detection resistor 14, and the second A / D conversion Means 15
Voltage Vs of the drive current detection resistor 14 input via
(T) and the drive current Ii of the drive circuit 11 from the resistance value Rs of the drive current detection resistor 14 stored in the memory in advance.
(T) is obtained, and from the current Ii (t), the L is stored in advance in the memory according to the relationship between the self-inductance L of the drive coil 12 in the fixed state and the drive current Ii (t) of the drive circuit 11. And the drive current Ii of the drive circuit 11
The load resistance Rl of the drive circuit 11 is calculated from (t) and this Rl
A current Iis (t) in a fixed state of the drive coil 12 from the L, the drive voltage Vi (t) of the drive circuit 11 input via the first A / D conversion means 13. Ask, this i
The voltage Vss (t) of the drive current detection resistor 14 in the fixed state of the drive coil 12 is calculated from is (t) and Rs, and Vss (t), Vs (t), and Rl are calculated. , Vv (t) = Rl / Rs {Vs (t) -Vss (t)} from the Rs, and a calculating means 16 for obtaining the speed signal Vv (t) of the drive coil 12.

[Work]

The drive voltage Vi (t) of the drive circuit 11 is the first A / D conversion means 13
The voltage Vs (t) of the drive current detection resistor 14 connected in series with the drive coil 12 is analog / digital converted by the second A / D conversion means 15. The calculation means 16 is driven from the voltage Vs (t) of the drive current detection resistor 14 input via the second A / D conversion means 15 and the resistance value Rs of the drive current detection resistor 14 stored in the memory in advance. The drive current Ii (t) of the circuit 11 is calculated, and this current Ii (t)
From the self-inductance L and the drive current Ii of the drive circuit 11 in the fixed state of the drive coil 12 stored in the memory in advance.
L is calculated from the relationship with (t) and the drive current of drive circuit 11 is calculated.
The load resistance Rl of the drive circuit 11 is calculated from Ii (t), and this Rl
, L, and the drive voltage Vi (t) of the drive circuit 11 input via the first A / D conversion means 13, the current Iis (t) in the fixed state of the drive coil 12 is obtained, and this Iis The voltage Vss (t) of the drive current detection resistor 14 in the fixed state of the drive coil 12 is calculated from (t) and Rs, and Vss (t), Vs (t) and Rl are calculated.
Then, the velocity signal Vv (t) of the drive coil 12 is obtained from the calculation of Rs by Vv (t) = Rl / Rs {Vs (t) -Vss (t)}.

〔Example〕

 FIG. 2 shows an embodiment of the present invention.

This embodiment is an example of the case where the drive coil 21 of the electromagnetic drive device is voltage-driven by the drive circuit 22 including an amplifier,
The drive current detection resistor 23 is connected in series with the drive coil 21. The drive voltage Vi (t) of the drive circuit 22 is A / D converted by the analog / digital (A / D) converter 24 and digitally converted.
The signal is input to the signal processor (DSP) 25, A / D converted by the voltage Vs (t) A / D converter 26 of the drive current detection resistor 23, and input to the DSP 25. The DSP25 is configured using a microcomputer, and the output voltage Vi of the A / D converter 24 is
The speed signal Vv (t) is calculated from (t) 'and the output voltage Vs (t)' of the A / D converter 26 and output. The speed signal Vv (t) from the DSP 25 is D / A converted by the digital / analog (D / A) converter 27, and the drive circuit 22 calculates the difference between the control signal and the speed signal from the D / A converter 27. Amplify and drive coil 21
And the drive current detection resistor 23 in series.

Next, the calculation of the DSP 25 will be described in detail.

The load resistance Rl of the drive circuit 22 is the DC resistance of the electromagnetic coil 21.
If Rc and the resistance value of the drive current detection resistor 23 are Rs, then Rl = Rc + Rs, and Rs is very small, about 20 to 1/30 of Rc. This Rl constantly changes depending on the heat generation of the electromagnetic coil 21 and the ambient temperature. So, in this embodiment,
Rm is measured every Tm, eg every 30 minutes to 1 hour.

The self-inductance L of the electromagnetic coil 21 is a function of the drive current Ii (t) of the drive circuit 22 and its frequency.
However, L changes almost negligibly with respect to the frequency of the drive current Ii (t). Therefore, the DSP 25 uses the drive current detection resistor 23 when the electromagnetic drive device is not operating (electromagnetic coil 21
The characteristic indicating the relationship between L and Ii (t) when (forcibly set to a fixed state) is measured in advance and stored in the memory. Here, when the electromagnetic coil 21 is fixed,
Ii (t) flowing through the drive current detection resistor 23 is only the current due to the drive voltage Vi (t) of the drive circuit 22, and the current Iv (t) due to the back electromotive force Ve (t) generated by the movement of the electromagnetic coil 21 is Not included.

When the drive voltage Vi (t) of the drive circuit 22 is output, the drive current Ii (t) flows through the drive coil 21, and the counter electromotive voltage Ve generated during the operation of the drive coil 11 flows through the drive current detection resistor 23.
A current Iv (t) resulting from (t) and a current Ii (t) resulting from the driving voltage Vi (t) flow to generate a voltage Vs (t). In order to obtain only the speed signal voltage Vv (t) proportional to the speed of the electromagnetic drive device (electromagnetic coil 21) (speed at which the electromagnetic coil 21 moves) from the voltage Vs (t) of the drive current detection resistor 23 From the voltage Vs (t) of the current detection resistor 23 to the drive current Ii
It is necessary to cancel the voltage component due to (t) to obtain the voltage component due to the current Iv (t), which is when the electromagnetic drive device is not operating (when the electromagnetic coil 21 is forcibly fixed).
Current Iis of the drive coil 11 with respect to the drive voltage Vi (t) of
It is necessary to find (t). That is, when the electromagnetic drive device in which the electromagnetic coil 21 is fixed is not operating, Ii (t) flowing through the drive current detection resistor 23 is equal to the drive voltage Vi of the drive circuit 22.
Since it is only the current due to (t) and does not include the current Iv (t) due to the counter electromotive voltage Ve (t) generated by the movement of the electromagnetic coil 21, the drive voltage Vi of the drive circuit 22 during the operation of the electromagnetic drive device.
The current flowing through the drive current detection resistor 23 due to (t) is the current Iis flowing through the drive current detection resistor 23 when the electromagnetic drive device is not operating.
It corresponds to (t). Therefore, when the electromagnetic drive device is operating, the current Iv (t) becomes Iv (t) = Ii (t) -Iis (t), and therefore Iis (t) needs to be obtained. In this case, since the resistance value Rs of the drive current detection resistor 23 is measured in advance and stored in the memory of the DSP 25 and is known, the DSP 25 determines the voltage Vs (t) of the drive current detection resistor 23 by the A / D converter 26. If it is taken in via Ii (t) = Vs (t) / Rs, Ii (t) can be obtained. As described above, since the DSP 25 stores the relationship between L and Ii (t) in the memory, L is obtained from Ii (t). Then, the DSP 25 measures R as described in, and drives voltage Vi (t) and Iis
The transfer function of (t) is However, since S: Laplace operator, these Rl, L and A /
From the drive voltage Vi (t) fetched via the D converter 24 to Iis
Find (t). Next, the DSP 25 uses the Iis (t) and Rs to determine the voltage Vss (t) = Iis (t) of the drive current detection resistor 23 when the electromagnetic drive device is not operating (when the electromagnetic coil 11 is forcibly fixed).
Calculates × Rs and detects drive current when the electromagnetic drive is operating
From the voltage Vs (t) of 23 to the voltage based on the drive current Ii (t) (voltage of the drive current detection resistor 23 when the electromagnetic drive is not operating)
The component corresponding to Vss (t) is canceled and the electromagnetic coil 21
If only the voltage component proportional to the moving speed of is obtained, this voltage component becomes {Vs (t) -Vss (t)}, The velocity signal Vv (t) is obtained by the following calculation.

FIG. 3 shows such a series of flow of this embodiment, and the portion within the chain line is performed by the DSP 25 as described above. If the transfer function of the drive current of the drive coil 21 and the moving speed in the portion outside the chain line is G (s), the speed V ₀ (s) of the electromagnetic drive device
Becomes Ii (s) · G (s), and if the effective magnetic flux of the electromagnetic drive device is Ba and the effective length of the drive coil 11 is l, the back electromotive force Ve
(S) becomes V ₀ (s) · Ba · l. This back electromotive force Ve
Current Ii (s) according to the difference between (s) and drive voltage Vi (s)
= {Vi (s) −Ve (s)} / {L (s) · S + Rl} flows into the drive coil 21.

FIG. 4 is a flow chart showing the processing flow of the DSP 25.

When the power is turned on, the DSP 25 first clears the timer value Tc in step S1, and inputs the test voltage Vt to the control signal input terminal of the drive circuit 22 in step S2. This test voltage
Vt is a minute voltage at which the drive coil 21 does not operate, and is set to a value such that Vi (t) is 0.5 V or less. Next, the DSP 25 takes in the voltage Vs (t) of the drive current detection resistor 23 via the A / D converter 26 in step S3, and then in step S3.
At 4, the calculation of Ii (t) = Vs (t) / Rs is performed. Next DSP25
Calculates the load resistance R1 by the calculation of Rl = Vt / Ii (t) from Ii (t) and Vt in step S5, and the test voltage Vt = 0 in step S6.
In this case, Vi (t) = 0 is set to adjust the offset of the drive circuit 22. Next, DSP25 is A / D converter in step S7.
The output voltage Vs (t) 'of 26 is checked to see if a control signal is input. If the control signal is not input to the drive circuit 22, this check is repeated. When the control signal is input, the DSP 25 proceeds to step S8 and takes in the drive voltage Vi (t) of the drive circuit 22 via the A / D converter 24, and in step S9, the voltage Vs of the drive current detection resistor 23. (T)
Is taken in through the A / D converter 26. Then, in step S10, the DSP 25 performs an operation of Ii (t) = Vs (t) / Rs from Rs stored in the above memory and Vs (t) just fetched, and in step S11, L and Ii ( Since the relationship with t) is stored in the memory, L is obtained from Ii (t). Then DS
P25 is Iis (t) = 1 / (L · S + Rl) × from Vi (t) taken from the A / D converter 24 in step S12 as described above, L just obtained, and Rl obtained above. Iis (t) is calculated by the operation Vi (t), and from this Iis (t) and Rs stored in the memory, Vss (t) = Iis (t) × Rs is calculated as Vss (t). Then, Vss (t), Vs (t) taken from the A / D converter 26, and R obtained above are obtained.
The velocity signal voltage Vv (t) is calculated from l and Rs stored in the memory by the calculation of Vv (t) = Rl / Rs × (Vs (t) −Vss (t)). Next, DSP2
In step S13, the value Tc of the timer is incremented by the timer period Ts in step S13 and the speed signal V obtained in step S14 is calculated.
Output v (t). Next, the DSP 25 checks the timer value Tc in step S15 and returns to step S7 if Tc ≧ Tm, and if Tc ≧ Tm proceeds to step S16 to check whether or not a control signal is input to the drive circuit 22. Then, the DSP 25 returns to step S8 when the control signal is input, and when the control signal is not input, clears the timer value Tc in step S17 and returns to step S2.

FIG. 5 shows another embodiment of the present invention.

In this embodiment, the drive coil 21 of the electromagnetic drive is a drive circuit 28.
In the above embodiment, the comparator 29 compares the control signal with the speed signal from the D / A converter 27 and outputs the difference. Then, the drive circuit 28 supplies a current according to the difference between the output signal of the comparator 29 and the voltage of the drive current detection resistor 23 to the drive coil 11 and the drive current detection resistor 23.
Supply to.

FIG. 6 shows another embodiment of the present invention.

In this embodiment, the drive coil 21 of the electromagnetic drive is a drive circuit 22.
In the above embodiment, the DSP 31 performs the same processing as that of the DSP 25, and a control signal is input through the A / D converter 32 to change the speed from the control signal. The signal is calculated and the result is output to the D / A converter 27. Then, the drive circuit 22 amplifies the output voltage of the D / A converter 27 and applies it to the drive coil 11.

The present invention is not limited to the above embodiment,
For example, it can be used for a speed control device of a DC motor.

〔The invention's effect〕

As described above, according to the present invention, there is provided a speed signal detection device of an electromagnetic drive device for detecting a speed signal of a drive coil driven by a drive circuit, wherein the drive voltage Vi (t) of the drive circuit is analog / digital. A first A / D converting means for converting, a drive current detecting resistor connected in series with the drive coil, and a second V / (t) voltage of the drive current detecting resistor for analog / digital conversion.
A / D conversion means, the voltage Vs (t) of the drive current detection resistance input via the second A / D conversion means, and the resistance value Rs of the drive current detection resistance stored in the memory in advance. The drive current Ii (t) of the drive circuit is obtained from
From (t), the L is obtained from the relationship between the self-inductance L in the fixed state of the drive coil stored in advance in the memory from the drive current Ii (t) of the drive circuit, and the drive current Ii ( t) to the load resistance of the drive circuit
Rl is obtained, and Rl, the L, and the drive voltage Vi (t) of the drive circuit input via the first A / D conversion means.
The current Iis (t) in the fixed state of the drive coil is obtained from and the voltage Vss (t) of the drive current detection resistor in the fixed state of the drive coil is calculated from this Iis (t) and Rs. The Vss (t), the Vs (t), the Rl,
The driving coil is forcibly forcibly provided with the calculating means for obtaining the speed signal Vv (t) of the driving coil by the calculation of Vv (t) = Rl / Rs {Vs (t) -Vss (t)} from Rs. The speed signal in the fixed state can be set to 0, and a high S / N speed signal can be obtained. Moreover, the calculation means can be digitized (made into software), the calculation speed can be improved, and the S / N of the speed signal can be further increased. Therefore, when used in a speed control circuit that controls the speed of an electromagnetic drive device, the speed control band can be significantly expanded by increasing the servo gain during speed control, and transient characteristics can be improved and It is possible to increase the control speed. Further, by digitizing the arithmetic operation by the arithmetic means, it becomes possible to incorporate the arithmetic means into the integrated circuit to reduce the size of the device.

[Brief description of drawings]

FIG. 1 is a block diagram showing the configuration of the present invention, FIG. 2 is a block diagram showing an embodiment of the present invention, FIG. 3 is a system diagram showing a processing flow of the same embodiment, and FIG. DSP in the example
5 and 6 are block diagrams showing other embodiments of the present invention, and FIG. 7 is a block diagram showing a speed signal detecting device of a conventional electromagnetic drive device. 11 …… Drive circuit, 12 …… Drive coil, 13 …… First A / D
Conversion means, 14 ...... Drive current detection resistance, 15 ... Second A / D
Conversion means, 16 ... Calculation means.

Continuation of the front page (56) Reference JP 63-80787 (JP, A) JP 56-88686 (JP, A) JP 58-201068 (JP, A) JP 56-159983 (JP , A)

Claims (1)

[Claims] 1. A speed signal detection device for an electromagnetic drive device for detecting a speed signal of a drive coil driven by a drive circuit, comprising: a first drive circuit for converting a drive voltage Vi (t) of the drive circuit into an analog / digital signal. A / D conversion means, a drive current detection resistor connected in series with the drive coil, and a second Vs (t) voltage of the drive current detection resistor for analog / digital conversion.
A / D conversion means, the voltage Vs (t) of the drive current detection resistance input via the second A / D conversion means, and the resistance value Rs of the drive current detection resistance stored in the memory in advance. The drive current Ii (t) of the drive circuit is obtained from
From (t), the L is obtained from the relationship between the self-inductance L in the fixed state of the drive coil stored in advance in the memory from the drive current Ii (t) of the drive circuit, and the drive current Ii ( t) to the load resistance of the drive circuit
Rl is obtained, and Rl, the L, and the drive voltage Vi (t) of the drive circuit input via the first A / D conversion means.
The current Iis (t) in the fixed state of the drive coil is obtained from and the voltage Vss (t) of the drive current detection resistor in the fixed state of the drive coil is calculated from this Iis (t) and Rs. The Vss (t), the Vs (t), the Rl,
An electromagnetic drive comprising: a calculation means for obtaining the speed signal Vv (t) of the drive coil by the calculation of Vv (t) = Rl / Rs {Vs (t) -Vss (t)} from Rs. Device speed signal detector.