JP3655117B2 - Sensor device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a sensor device that incorporates a switching power supply circuit, converts a change in a physical quantity such as a rotational position into a weak electric signal by a sensor such as a resolver, and further converts it into a digital signal.
[0002]
[Prior art]
FIG. 3 shows an example of a block diagram showing a conventional configuration of a rotational position sensor device using a resolver, which is a rotational position sensor using magnetism. 4 shows a timing chart for explaining the operation of the conventional rotational position sensor device of FIG. In FIG. 3, the resolver 1 includes excitation coils 2a, 2b, 2c, and 2d and detection coils 3a, 3b, 3c, and 3d. The AC excitation circuit 5 amplifies the excitation signal exs from the timing controller 9 (hereinafter referred to as TC9) and applies an AC voltage to the excitation coils 2a to 2d. The detection coils 3a and 3c, 3b and 3d are connected in pairs, and the rotor 4 rotates from the detection coils 3a to 3d connected in pairs according to the change in the magnetic resistance due to the change in the rotation position of the rotor 4. An output that is amplitude-modulated to a sine value and a cosine value of each angle is obtained. Output signals from the resolver 1 are input to differential amplifiers 6a and 6b, respectively, and then input to analog / digital converters 8a and 8b (hereinafter referred to as A / D converters 8a and 8b) via the amplifiers 7a and 7b, respectively. The
[0003]
In TC9, the A / D converters 8a and 8b perform various operation commands and timing adjustments necessary for performing digital conversion processing, and excitation signal generation to the AC excitation circuit 5 and the like. In the A / D converters 8a and 8b, as shown in FIG. 4, an A / D conversion start command adst that is synchronized with the excitation signal exs from the TC 9 and is output at a timing when the output of the resolver 1 reaches a peak, The input resolver output signal is sampled and held, and the analog signal after the hold is converted into digital data. Then, the resolver signal converted into digital data is output to the CPU 10. In the CPU 10, the interrupt signal tint output after completion of A / D conversion from the TC 9 is used as a trigger to perform arithmetic processing with the two-phase resolver signals transmitted from the A / D converters 8a and 8b, and obtain rotational position data pos. .
[0004]
On the other hand, in the rotational position sensor device, a switching power supply circuit 11 is used as a power supply circuit for reducing the influence of fluctuations in the supplied power supply voltage, preventing heat generation due to power stabilization, and improving the detection accuracy of the rotational position sensor. Is built-in. A step-down regulator circuit, which is a switching power supply circuit 11 using a switching regulator controller 12 (hereinafter referred to as SRC 12), includes an SRC 12, a transistor 13, a diode 14, a choke coil 15, and a capacitor 16. The power supply voltage Vin of the rotational position sensor device supplied from the outside is input to the emitter terminal of the transistor 13 and the power supply terminal of the SRC 12. The output terminal of the SRC 12 is connected to the base terminal of the transistor 13. Then, as shown in FIG. 4, the SRC 12 can obtain a stabilized output voltage used as a circuit power source of the rotational position sensor device with less heat generation by controlling the ON operation of the transistor 13 by pulse width modulation. it can. Although not shown in the figure, the SRC 12 can generally adjust various settings related to the operation of the SRC 12 such as an operating oscillation frequency by connecting resistors and capacitors.
[0005]
[Problems to be solved by the invention]
The switching power supply circuit 11 obtains a stabilized power supply using the magnetic energy accumulated in the choke coil 15, and the switching regulator controller 12 is connected to the output of the transistor 13 provided for current amplification. Voltage control is performed by changing the on / off time, that is, by controlling the pulse width. Therefore, a large magnetic change occurs in the choke coil 15 due to the switching operation of the switching regulator controller 12. There has been a problem that this magnetic noise is mixed into a sensor that outputs a weak signal or an amplifier for the sensor signal. In particular, in the case of a sensor using magnetism such as a resolver, the sensor is directly affected by a magnetic change in the choke coil 15 provided in the switching power supply circuit 11, and the detection accuracy may be deteriorated. Furthermore, recently, there has been a demand for miniaturization and high accuracy of the sensor device, and the sensor and the power supply circuit are becoming increasingly adjacent to each other. Therefore, the influence of magnetic noise generated in the power supply circuit is increased. It can no longer be ignored.
[0006]
[Means for Solving the Problems]
In order to solve the above-described problems, a sensor device that converts a change in physical quantity into data of a digital signal by a sensor that converts a change in physical quantity into an electrical signal. In the present invention, the electrical signal from the sensor is sampled in the present invention. Analog / digital conversion means for converting to digital data; switching power supply means having a switching operation stop function; and for the switching power supply means, at least the analog / digital conversion means completes sampling of the electrical signal and a timing control means for outputting a stop signal for stopping the switching operation from the time t to the completion of the sample. The sensor may be a position sensor that detects a rotational position or a linear position using magnetism.
[0007]
According to the present invention, in the analog / digital conversion means for converting an analog signal from a sensor into digital data, each operation command is output from a predetermined time before completion of sampling of the input signal to completion of sampling. When the timing control means outputs a switching operation stop signal to the switching power supply means and stops the switching operation, the analog / digital conversion means receives the noise at the time of sampling of the sensor signal from the switching power supply means. Therefore, it is possible to suppress deterioration in detection accuracy of the sensor due to the influence of magnetic noise from the switching power supply means.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
An embodiment of the sensor device of the present invention will be described below with reference to FIGS. FIG. 1 is a block diagram showing a configuration of a rotational position sensor device according to the present embodiment using a resolver, which is a rotational position sensor using magnetism as a sensor. FIG. 2 shows a timing chart for explaining the operation of the rotational position sensor device of the present embodiment. Also, the same components as those in the conventional example of FIGS. 3 and 4 are denoted by the same reference numerals, and the description thereof is omitted.
An AC voltage obtained by amplifying the excitation signal exs from TC9 by the AC excitation circuit 5 is applied to the excitation coil 2a-2d of the resolver 1, which is composed of the excitation coil 2a-2d and the detection coil 3a-3d. From the detection coils 3a to 3d, an output amplitude-modulated to a sine value and a cosine value of the rotational position of the rotor 4 is obtained. The two-phase outputs obtained from the resolver 1 are differentially amplified by the amplifiers 6a and 6b, respectively, and input to the A / D converters 8a and 8b via the amplifiers 7a and 7b. The A / D converters 8a and 8b sample and hold a two-phase signal according to an A / D conversion start command adst from the TC 9, and digitally convert the voltage after the hold and output it to the CPU 10.
[0009]
As shown in FIG. 2, the TC 9 performing each operation command and timing adjustment necessary for performing the digital conversion processing by the A / D converters 8a and 8b is synchronized with the A / D conversion start command adst. And at least a predetermined time t1 before the output of the A / D conversion start command adst, a time with a margin for the setup time, which is a time required for the A / D converters 8a and 8b to sample the input voltage, For example, the switching operation stop signal dtc for stopping the switching operation is output to the SRC 12 in the switching power supply circuit 11 from 5 μs before. When the switching operation stop signal dtc is input to the SRC 12, the output terminal of the SRC 12 connected to the base terminal of the transistor 13 is held at the “H” level. As a result, the transistor 13 is turned off, and the magnetic change in the choke coil 15 is rapidly reduced.
The TC 9 considers the time required to complete the sample and hold the input voltage at least inside the A / D converters 8 a and 8 b after outputting the switching operation stop signal dtc to the SRC 12. After a predetermined time t2 when the D conversion start command adst is output, for example, after 2 μs, the switching operation stop signal dtc of the SRC 12 is canceled. Note that the switching operation stop times t1 and t2 not only take into account the characteristics of the A / D converters 8a and 8b, but also directly affect the resolver 1 magnetically and deteriorate the detection accuracy. It is desirable to set the time when the magnetic fluctuation is sufficiently attenuated.
The CPU 10 performs arithmetic processing based on the two-phase resolver signal transmitted from the A / D converters 8a and 8b by the interrupt signal tint output from the TC9 after the A / D conversion is completed, and the rotational position data pos. obtain.
[0010]
According to the present embodiment configured as described above, the TC 9 outputting each operation command to the A / D converters 8a and 8b that convert the output signal of the resolver that is the rotational position sensor into digital data. Before outputting the A / D conversion start command adst, which is an operation command, to the A / D converters 8a and 8b, by issuing a switching operation stop command dtc to the SRC 12 in synchronization with the A / D conversion start command adst, Magnetic changes in the choke coil 15 immediately before completing the rotation position sensor signal sampling can be greatly reduced, and deterioration in detection accuracy due to the influence of magnetic noise from the switching power supply circuit 11 can be suppressed.
Further, when the switching operation of the switching power supply circuit 11 is stopped, a voltage drop occurs in the circuit power supply of the rotational position sensor device during the stop period, but the time for stopping the switching operation takes the above-mentioned points into consideration. However, there is no problem with the operation of the sensor device.
In addition, this invention is not limited to the said embodiment, In the range which does not change the summary, it can implement in various deformation | transformation. For example, although an example of a step-down regulator circuit has been shown for the switching power supply circuit 11, it can also be applied to a step-up regulator circuit according to the same principle.
[0011]
【The invention's effect】
As described above, according to the sensor device of the present invention, in the timing controller that controls the operation of the A / D converter, the operation of the switching power supply circuit is also controlled when the A / D converter is operated. As a result, it is possible to reduce the influence of magnetic noise from the switching power supply circuit, which is a problem when sampling the sensor signal, and to suppress deterioration in detection accuracy of the sensor.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a configuration of a sensor device according to an embodiment of the present invention.
FIG. 2 is a diagram illustrating a timing chart explaining the operation of the sensor device according to the present embodiment.
FIG. 3 is a block diagram showing a configuration of a conventional sensor device.
FIG. 4 is a timing chart illustrating the operation of a conventional sensor device.
[Explanation of symbols]
1 resolver, 2a, 2b, 2c, 2d excitation coil, 3a, 3b, 3c, 3d detection coil, 4 rotor, 5 AC excitation circuit, 6a, 6b amplifier, 7a, 7b amplifier, 8a, 8b A / D converter, 9 Timing controller, 10 CPU, 11 Switching power supply circuit, 12 Switching regulator controller, 13 Transistor, 15 Choke coil.

Claims (2)

In a sensor device that converts a change in physical quantity into digital signal data by a sensor that converts a change in physical quantity into an electrical signal,
Analog / digital conversion means for sampling an electrical signal from the sensor and converting it into digital data;
Switching power supply means having a switching operation stop function;
Timing control means for outputting to the switching power supply means a stop signal for stopping a switching operation at least from a predetermined time before the analog / digital conversion means completes sampling of the electrical signal to completion of sampling; A sensor device comprising: The sensor device according to claim 1, wherein the sensor is a position sensor that detects a rotational position or a linear position using magnetism.

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