JP2006080872A - Analog/digital converting device and stirling refrigeration system using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an analog/digital converting device capable of performing analog/digital conversion with high accuracy. <P>SOLUTION: A diode D is connected between a terminal for Ref-A/D of a microcomputer 1000 and a constant voltage circuit 400 connected to a power source electrode Vcc. Thus, voltage information (Vrin-ΔV) of a value lower than an output value Vrin of the constant voltage circuit 400 only by voltage drop ΔV of the diode D is inputted to a Ref-A/C conversion circuit. By using the value of the voltage drop ΔV of the diode D and the voltage information (Vrin-ΔV), analog/digital conversion is performed in an M-A/D conversion circuit. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an analog / digital conversion device for converting analog data into digital data and a Stirling refrigeration system using the same.

  Conventionally, as an analog / digital conversion device, a microcomputer in which an analog / digital conversion circuit is incorporated is used. A successive approximation type analog / digital conversion circuit incorporated in a conventional analog / digital conversion device will be described below with reference to FIGS. 10 and 11.

  As shown in FIG. 10, a conventional analog / digital conversion circuit includes a comparator having one terminal to which analog data is input from an analog input terminal via a resistor, and a resistor for one terminal of the comparator. And a D-A (Digital to Analog) converter that outputs analog data via the A / D converter. Further, the ground potential data is input from the ground electrode to the other terminal of the comparator. The D-A converter receives a reference voltage Vref. A digital value is transmitted from the program circuit to the DA converter, and the DA converter creates an analog voltage corresponding to a predetermined digital value based on the input reference voltage Vref. The output of the comparator is output to the program circuit. Further, the clock signal generated by the clock generator is input to the program circuit. The program circuit converts the analog data into digital data and transmits it to the output register at a predetermined time measured by the clock signal. The output register outputs digital data. The conversion principle of the successive approximation type AD converter shown in FIG. 10 as described above is as follows.

  First, the most significant bit of 8-bit length of the DA converter is set to 1 by the program circuit. As a result, digital data “10000000” in which the most significant bit is 1 and all other bits are 0 in the DA converter is converted into the comparison voltage Vc and output. The comparison voltage Vc is input to one input terminal of the comparator. The comparator compares the magnitude of the comparison voltage Vc (DA conversion value) and the input analog voltage Vin input to the analog input terminal. When the input voltage Vin is higher than the comparison voltage Vc, the output of the comparator is 1, and 1 is set at the most significant 8-bit length of the DA converter. On the other hand, when the input analog voltage Vin is lower than the comparison voltage Vc, the output of the comparator is 0, and 0 is set (reset) at the most significant 8-bit length of the DA converter.

Next, the second most significant bit is set to 1, and the same processing as when the most significant bit is set to 1 is executed. These processes are performed in order from the highest level to the lowest level. That is, when the analog / digital converter has an 8-bit resolution, the comparison voltage Vc is sequentially updated from V1 to V8, and each comparison voltage Vc (c = 1, 2, 3, 4, 5). , 6, 7, 8) and the input voltage Vin are compared, and the output data of the output register when all the bits are set (1) or reset (0) are final AD (Analog to Digital). ) Conversion value. The aforementioned analog / digital conversion concept is shown in FIG. In the example of FIG. 11, the output digital value is 10010101.
JP-A-61-199101 JP-A 1-1114762 JP 2000-131093 A

  In the conventional analog / digital conversion circuit, the output voltage of the constant voltage circuit is applied as the reference voltage Vref to the analog / digital conversion terminal connected thereto. The A / D conversion circuit performs analog / digital conversion on the premise that the reference voltage Vref does not vary for each constant voltage circuit provided in each product. Therefore, in a control device having an analog / digital conversion circuit, data indicating the value of the reference voltage Vref is incorporated in the internal program in advance, and analog / digital conversion is performed using the value.

  Therefore, if the actual value of the reference voltage Vref varies for each product and is different from the value stored in the program inside the product, the comparison voltage Vc output from the DA converter to the comparator The value is different from the output digital value output from the program circuit to the DA converter. As a result, the output digital value output from the program circuit to the output register is different from the actual input analog voltage value.

  In such A / D conversion, when a slight error is allowed in the output digital value, the value of the reference voltage Vref common to each product stored in the program without any problem is used. can do. However, even if the error included in the output digital value is small, if the error causes inconvenience, the actual values of the reference voltage Vref and the reference voltage Vref stored in the microcomputer in advance as a constant value common to each product. It is problematic that the value is different from the value of I, that is, the accuracy of analog / digital conversion is low.

  The above-mentioned variation in the reference voltage Vref for each product usually depends on the variation in the performance of the constant voltage circuit incorporated in each product. If it is attempted to reduce the variation in performance of the constant voltage circuit for each product, the cost of the constant voltage circuit increases. In this case, since the voltage output from the constant voltage circuit needs to be considerably smaller than the power supply voltage, the numerical range that can be converted from analog to digital is narrowed. In other words, the accuracy of analog / digital conversion could not be improved by a simple method.

  The present invention has been made in view of the above-described problems, and an object of the present invention is to provide an analog / digital conversion apparatus capable of performing analog / digital conversion with high accuracy by a simple method, and Stirling using the same. It is to provide a refrigeration system.

  An analog / digital conversion device according to one aspect of the present invention includes a control device and a peripheral circuit electrically connected between the control device and a power source.

  The control device includes a reference voltage terminal to which a reference voltage is applied, one and other analog / digital conversion terminals that receive analog information, and one and other analog / digital conversions that create digital information corresponding to the analog information. A circuit and a central processing unit for performing operations using digital information. The peripheral circuit includes a voltage drop circuit which is connected between one analog / digital conversion terminal and a power supply and drops the reference voltage by a predetermined drop voltage.

  One analog / digital conversion circuit receives one voltage information value lower than the other analog / digital conversion circuit by a predetermined voltage drop, and outputs one output digital value corresponding to the one voltage information. . The central processing unit uses one output digital value, a digital value corresponding to a predetermined voltage drop stored in advance, and an output digital value corresponding to a predetermined reference voltage to determine the actual value of the reference voltage. Is calculated. Other analog / digital conversion circuits convert analog information into digital information using the actual value of the reference voltage.

  According to said structure, the precision of analog / digital conversion can be improved easily.

  An analog / digital conversion device according to another aspect of the present invention includes a control device and a peripheral circuit electrically connected between the control device and a power source.

  The control device includes a reference voltage terminal to which a reference voltage is applied, one and other analog / digital conversion terminals that receive analog information, and one and other analog / digital conversions that create digital information corresponding to the analog information. A circuit and a central processing unit for performing operations using digital information.

  The peripheral circuit includes a constant voltage circuit that is connected between one analog / digital conversion terminal and a power source and applies a constant voltage smaller than a reference voltage to the one analog / digital conversion terminal. The one analog / digital conversion circuit receives information on a constant voltage and outputs one output digital value corresponding to the information on the constant voltage. The central processing unit calculates an actual value of the reference voltage using one output digital value, a digital value corresponding to a predetermined voltage stored in advance, and an output digital value corresponding to a predetermined reference voltage. To do. Other analog / digital conversion circuits convert analog information into digital information using the actual value of the reference voltage.

  The analog / digital conversion apparatus can also easily improve the accuracy of analog / digital conversion.

  The Stirling refrigeration system of the present invention includes an inverter circuit that generates AC power using DC power, a linear motor that is supplied with AC power, a piston that reciprocates by the linear motor, and pressure fluctuations caused by the reciprocating motion of the piston A displacer that reciprocates by means of, a measuring circuit that measures the voltage of DC power, and the analog / digital converter described above. In the Stirling refrigeration system, analog voltage information specifying the voltage of the DC power output from the measurement circuit is input to another analog / digital conversion terminal of the analog / digital conversion device.

  According to said structure, the alternating current waveform applied to a linear motor can be approximated to an ideal sine curve. Therefore, each reciprocating motion of the piston and the displacer becomes an ideal simple vibration. As a result, vibration of the Stirling refrigerator can be reduced.

  According to the present invention, analog / digital conversion with high accuracy is possible.

  Hereinafter, an analog / digital conversion apparatus and an analog / digital conversion method according to an embodiment of the present invention will be described with reference to FIGS.

(Embodiment 1)
As shown in FIG. 1, the analog / digital conversion device according to the present embodiment includes a constant voltage circuit 400 connected to a power supply electrode Vcc (5 V) and a micro voltage connected to the power supply electrode Vcc via the constant voltage circuit 400. And a computer 1000. The microcomputer 1000 functions as a control device of the present invention. Each of the Vcc terminal and the Vref (Reference) terminal of the microcomputer 1000 is connected to the constant voltage circuit 400. The constant voltage circuit 400 is a circuit that outputs DC power having a voltage of 5 V (± 4% error is allowed for each product). In other words, the constant voltage circuit 400 outputs a voltage of 5.2V, and some outputs a voltage of 4.8V. In other words, the output voltage of the constant voltage circuit 400 varies from product to product. The Vref terminal is a terminal to which a reference voltage Vref used in the microcomputer 1000 is applied. Information on the reference voltage Vref applied to the Vref terminal is input to a CPU (Central Process Unit). Information on the reference voltage Vref is sent from the CPU to an A / D conversion circuit described later.

  A diode D is connected in the forward direction between the Ref-A / D (Analog / Digital) terminal and the constant voltage circuit 400. Further, the M / A / D terminal is connected to the linear motor M. The Tc-A / D terminal is connected to the temperature sensor 34. The Th-A / D terminal is connected to the temperature sensor 35. The TbA / D terminal is connected to the temperature sensor 36. Further, a GND (Ground) terminal of the microcomputer 1000 is connected to the ground electrode GND.

  The Ref-A / D terminal is connected to a Ref-A / D conversion circuit inside the microcomputer 1000. The M / A / D terminal is connected to the M / A / D conversion circuit in the microcomputer 1000. The Tc-A / D terminal is connected to a TcA / D conversion circuit inside the microcomputer 1000. The Th-A / D terminal is connected to a Th-A / D conversion circuit inside the microcomputer 1000. The Tb-A / D terminal is connected to a Tb-A / D conversion circuit inside the microcomputer 1000.

  Each of the aforementioned A / D conversion circuits is an analog / digital conversion circuit that converts analog data into digital data, and is connected to a CPU in the microcomputer 1000 in the same manner as the Vref terminal. Further, the CPU supplies the reference voltage Vref to each A / D conversion circuit. Thereby, each A / D conversion circuit converts analog data into digital data based on the reference voltage Vref applied to the Vref terminal. The CPU is connected to a RAM (Random Access Memory) and is also connected to a ROM (Read Only Memory). According to the analog / digital conversion device of the present embodiment as shown in FIG. 1, the diode D is connected between the constant voltage circuit 400 and the Ref-A / D terminal. The analog / digital conversion in each of the A / D conversion circuits other than the Ref-A / D conversion circuit is performed with higher accuracy.

  The principle of analog / digital conversion in this embodiment will be described with reference to FIG.

  FIG. 2 shows an input analog voltage Vin applied to each A / D terminal (for example, an MA / D conversion circuit) other than the Ref-A / D terminal, and an A corresponding to the A / D terminal. It is a figure for demonstrating the relationship with the output digital value Vout output from a / D conversion circuit. Since the input analog voltage Vin and the output digital value Vout are in a proportional relationship, a line indicating the mutual relationship in FIG. 2 is a straight line passing through the origin O.

  A voltage drop (good accuracy) when the input analog voltage Vin drops by a constant voltage due to the diode D is assumed to be ΔV. The digital value of ΔV is measured in advance and written in the ROM. In this case, an input analog voltage (Vin−ΔV) is applied to the Ref-A / D terminal. Note that the value of the drop voltage ΔV must have a variation width for each product smaller than a variation width for each product of the constant voltage circuit 400. This is because it is an object of the present invention to reduce the error of the output digital value of the A / D conversion circuit due to the variation of the output voltage of the constant voltage circuit 400 for each product.

The output digital value output from the Ref-A / D conversion circuit to the CPU after A / D conversion is defined as Drout. Note that the analog / digital conversion circuit of this embodiment can associate ¹⁰ -bit (2 ¹⁰ = 1023) digital data with analog data. That is, the resolution of analog / digital conversion is 10 bits.

  Therefore, from FIG. 2, the output digital value Dout of each of the M-A / D conversion circuit, the Tc-A / D conversion circuit, the Th-A / conversion circuit, and the Tb-A / D conversion circuit is expressed by the following formula ( It can be seen that 1) is calculated.

Dout = ((1023-Drout) / ΔV) × Vin (1)
Here, when the input analog voltage Vin = the reference voltage Vref, in the 10-bit resolution analog / digital conversion circuit, since the output digital value Dout = 1023 with respect to the input analog voltage Vin, the actual value of the reference voltage Vref is It is calculated by the following equation (2).

Vref = (1023 × ΔV) / (1023-Drout) (2)
Therefore, the digital value of the drop voltage ΔV is stored in advance in the ROM of the microcomputer 1000, and the output digital value Drout corresponding to the input analog voltage (Vin−ΔV) input to the Ref-A / D conversion circuit is Since the Ref-A / D conversion circuit always outputs to the CPU, the CPU uses the digital value of the drop voltage ΔV and the output digital value Drout to determine the actual value of the reference voltage Vref applied to the Vref terminal. The output digital value corresponding to can be calculated.

  Thus, according to the analog / digital conversion apparatus of the present embodiment, the Ref-A / D conversion circuit, which is an analog / digital conversion circuit that is connected to the diode D and is not used for actual analog / digital conversion, is provided. Therefore, analog / digital conversion can be performed using the reference voltage Vref with higher accuracy. This is because the actual value (digital value) of the reference voltage Vref can be easily calculated even when the reference voltage Vref varies for each constant voltage circuit 400 of each product.

  Next, the analog / digital conversion process (1) performed in the microcomputer 1000 of this embodiment will be described with reference to FIG.

  First, in S1, the CPU acquires the output digital value Drout of the RefA / D conversion circuit. Next, in S2, the CPU reads the digital value of the drop voltage ΔV of the diode D previously written in the ROM from the ROM. Thereafter, in S3, the CPU calculates a reference voltage Vref = (1023 × ΔV) / (1023−Drout) using the output digital value Drout and the digital value of the drop voltage ΔV. The actual value (digital value) of the reference voltage Vref is transmitted from the CPU to each A / D conversion circuit. Next, in S4, each comparison voltage Vc is determined using the actual value of the reference voltage Vref. Note that c = 1, 2,..., 10).

  Each comparison voltage Vc is an analog value with respect to a digital value when 1 is sequentially set from the most significant bit to the least significant bit among the 10 bits, as described in the background art section. As described with reference to FIG. 10, each comparator voltage Vc (c = 1 to 10) and each input analog voltage input to each A / D terminal other than the Ref-A / D terminal by the comparator. Vin is sequentially compared, and the comparison result is sequentially transmitted from the program circuit to the output register. Thereafter, in step S5, in each of the A / D conversion circuits (for example, the MA / A conversion circuit) other than the Ref-A / D conversion circuit, the output register outputs the digital value Degi with respect to the input analog voltage Vin. To do.

  In FIG. 1, a diode is shown as a step-down circuit that causes a voltage drop by a constant drop voltage ΔV, but another step-down circuit may be used instead of the diode. However, as described above, the width of variation of the voltage drop due to the step-down circuit for each product must be smaller than the width of variation of the voltage output from the constant voltage circuit 400 for each product.

(Embodiment 2)
Next, the analog / digital conversion apparatus according to the second embodiment will be described with reference to FIGS.

  The analog / digital conversion device shown in FIG. 4 is substantially the same as the analog / digital conversion device shown in FIG. In the analog / digital conversion device shown in FIG. 4, only the variable resistor VR is used in place of the diode D of the analog / digital conversion device shown in FIG. And different. The variable resistor VR has one end connected to the Ref-A / D conversion terminal, the other end connected to the ground electrode, and an intermediate position connected to the constant voltage circuit 400.

  Note that the width of the variation of the voltage applied to the variable resistor VR for each product must be smaller than the width of the variation of the output voltage of the constant voltage circuit 400 for each product. This is because it is an object of the present invention to reduce the error of the output digital value caused by variations in the output of the constant voltage circuit 400.

  Next, the principle of analog / digital conversion of this embodiment will be described with reference to FIG.

  FIG. 5 shows an input analog voltage Vin applied to each A / D terminal (for example, an MA / D conversion circuit) other than the Ref-A / D terminal, and an A corresponding to the A / D terminal. It is a figure for demonstrating the relationship with the output digital value Vout output from a / D conversion circuit. Also in FIG. 5 of the present embodiment, as in FIG. 2 of the first embodiment, the input analog voltage Vin and the output digital value Vout are in a proportional relationship, and a line indicating the relationship is a straight line passing through the origin O. It has become.

A constant voltage input to the Ref-A / D conversion circuit adjusted by the variable resistor VR is Vrin. A digital output value output from the Ref-A / D conversion circuit to the CPU after A / D conversion is defined as Drout. Note that the analog / digital conversion circuit of this embodiment can make ¹⁰ -bit (2 ¹⁰ = 1023) digital data correspond to analog data. That is, the resolution of analog / digital conversion is 10 bits.

  Therefore, the output digital value Dout of each of the M-A / D conversion circuit, the TcA / D conversion circuit, the ThA / conversion circuit, and the TbA / D conversion circuit is calculated by the following equation (3).

Dout = (Drout / Drin) × Vin (3)
When the input analog voltage Vin = the reference voltage Vref, the 10-bit resolution analog / digital conversion circuit has the output digital value Dout = 1023 with respect to the input analog voltage Vin, and therefore the actual reference voltage Vref applied to the Vref terminal. The value of is represented by the following equation (4).

Vref = 1023 / (Vrin / Drout) (4)
Therefore, if the digital value of the constant voltage Vrin applied to the Ref-A / D conversion circuit is stored in advance in the ROM of the microcomputer 1000, the output digital value corresponding to the constant voltage Vrin of the Ref-A / D conversion circuit. Since Drout is always output from the Ref-A / D conversion circuit to the CPU, the CPU can easily calculate the actual value (digital value) of the reference voltage Vref.

  Thus, according to the analog / digital conversion device of the present embodiment, the input analog voltage applied to the Ref-A / D terminal using the variable resistor VR having one end connected to the ground electrode. Since a certain constant voltage Vin is measured in advance and stored in the ROM, analog / digital conversion with higher accuracy can be performed. The reason is that the CPU easily calculates the actual value (digital value) of the reference voltage Vref even when the reference voltage Vref output from the constant voltage circuit 400 varies for each constant voltage circuit 400 of each product. This is because it can.

  An analog / digital conversion method performed using the analog / digital conversion apparatus in FIG. 4 will be described with reference to the flowchart of FIG.

  First, preparation steps are performed. In the preparation stage, the variable resistor VR is adjusted, and the value of the constant voltage Vrin that is an input analog voltage input to the Ref-A / D conversion circuit is measured outside the microcomputer 1000. The input analog voltage Vref is measured by measuring the voltage between the Ref-A / D terminal connected to the variable resistor VR and the constant voltage circuit 400 using a voltage measuring device. Further, the constant voltage Vrin is stored in the ROM of the microcomputer 1000. This operation is performed by writing the value of the input analog voltage Vrin in the ROM in advance.

  Next, analog / digital conversion processing (2) shown in FIG. 6 is performed. This processing is performed by the CPU of the microcomputer 1000. In the analog / digital conversion process (2), a process of reading the constant voltage Vrin from the ROM is executed in SSS0. Thereafter, in SSS1, a process of acquiring the output digital value Vrout output from the Ref-A / D conversion circuit is executed. Next, in SSS2, a process of calculating a reference voltage Vref = 1023 × (Vrin / Drout) is executed. Thereafter, in SSS3, a process of determining each comparison voltage Vc using the reference voltage Vref is executed. Note that c = 1, 2,...

  The comparison voltage Vc is an analog value with respect to a digital value when 1 is sequentially set from the most significant bit of the 10 bits to the least significant bit, as described in the background art column. As described with reference to FIG. 10, each comparator voltage Vc (c = 1 to 10) and the input analog voltage Vin input to each of the A / D terminals other than the Ref-A / D conversion circuit by the comparator. Are sequentially compared, and the comparison result is transmitted from the program circuit to the output register. Thereafter, in SSS4, the output register outputs a digital value Degi for the input analog voltage Vin to the CPU.

  As described above, according to the analog / digital conversion method of the present embodiment, since the constant voltage Vrin, which is the input analog voltage of the Ref-A / D conversion circuit, is stored in the ROM in advance, it is applied to the Vref terminal. Even if the reference voltage Vref varies from product to product, the analog voltage input to each A / D conversion circuit other than the Ref-a / D conversion circuit can be converted to a digital value with high accuracy. It has become.

  In the above example, the variable resistor is shown as a constant voltage circuit that applies a predetermined constant voltage to the Ref-A / D terminal. However, a predetermined voltage can be applied to the Ref-A / D terminal. In the case of a constant voltage circuit (voltage regulator), a constant voltage diode (zener diode) Dz shown in FIG. 7 may be used. However, even in this case, the width of the variation of the output value of the constant voltage diode Vz used instead of the variable resistor VR for each product is the width of the variation of the output value of the constant voltage circuit 400 for each product. Need to be smaller.

  A Stirling refrigerator that can be used more effectively if the microcomputer having the analog / digital conversion circuit of the above embodiment is used will be described below.

  In the Stirling refrigerator, as will be described later, the piston reciprocates by the linear motor, and thereby the displacer reciprocates. In addition, one end of each of the piston and the displacer is fixed to a spring. Therefore, unless an AC voltage that draws an ideal sine curve is applied to the linear motor M that drives the piston, the reciprocating motion of the piston and the displacer does not become an ideal single vibration, and the Stirling refrigerator may vibrate. There is. If the above-mentioned analog / digital conversion device is used, analog data necessary for making the waveform of the AC voltage applied to the linear motor an ideal sine curve, for example, an inverter circuit for controlling the linear motor M is input. It becomes possible to grasp the value of the DC voltage with higher accuracy. Therefore, the analog / digital conversion device of the above-described embodiment is very suitable for controlling the Stirling refrigerator 40. The Stirling refrigeration system of the present invention includes the Stirling refrigerator 40 and the analog / digital converter described above.

  Hereinafter, the implementation of the Stirling refrigerator will be described with reference to the drawings.

  FIG. 8 is a cross-sectional view showing the Stirling refrigerator 40 of the embodiment. In the Stirling refrigerator 40, a cylindrical piston 1 and a displacer 2 are fitted in a cylindrical cylinder 3 composed of two parts. The piston 1 and the displacer 2 are provided via a compression space 9 and have an axis Y as a common drive shaft.

  An expansion space 10 is formed on the tip side of the displacer 2. The compression space 9 and the expansion space 10 communicate with each other via a medium flow passage 11 through which a working medium such as helium flows. A regenerator 12 is provided in the medium flow path 11. The regenerator 12 accumulates the heat of the working medium and supplies the accumulated heat to the working medium. A flange (flange) 3 a is provided in the middle of the cylinder 3. A bounce space (back space) 8 is formed in the flange portion 3a by being sealed with a dome-shaped pressure vessel 4 attached thereto.

The piston 1 is integrated with the support spring 5 on the rear end side. The displacer 2 is integrated with the support spring 6 through a rod 2a that passes through the center hole 1a of the piston 1. The support spring 5 and the support spring 6 are connected by a bolt and a nut 22. As will be described later, when the piston 1 reciprocates, the displacer 2 reciprocates with a predetermined phase difference with respect to the piston 1 due to inertial force generated between the piston 1 and the displacer 2.

  An inner yoke 18 is fitted on the outer side of the cylinder 3 in the bounce space 8. The outer yoke 17 is opposed to the inner yoke 18 through a gap 19. A driving coil 16 is fitted inside the outer yoke 17. An annular permanent magnet 15 is movably provided in the gap 19. The permanent magnet 15 is integrated with the piston 1 through a cup-shaped sleeve 14. The inner yoke 18, the outer yoke 17, the driving coil 16, and the permanent magnet 15 constitute a linear motor 13 (M) that moves the piston 1 along the axis Y.

  Lead wires 20 and 21 are connected to the driving coil 16. The lead wires 20 and 21 pass through the wall surface of the pressure vessel 4 and are connected to the control device 30. Driving power is supplied to the linear motor 13 (M) by the inverter circuit 100.

  In the Stirling refrigerator 40 having the above configuration, when the piston 1 reciprocates by the linear motor 13 (M), the displacer 2 reciprocates with a predetermined phase difference with respect to the piston 1. As a result, the working medium moves between the compression space 9 and the expansion space 10. As a result, a reverse Stirling cycle is formed.

  In the Stirling refrigerator 40 of the present embodiment described above, when a drive voltage having a predetermined AC waveform is applied to the linear motor 13 (M) by the control device 30, the piston 1 corresponds to the drive voltage having the predetermined AC waveform. The reciprocating motion is performed with the specified cycle and stroke. Therefore, it is possible to control the cycle and stroke of the reciprocating motion of the piston 1 by controlling the drive voltage applied to the linear motor 13.

  Next, the operation principle of the free piston type Stirling refrigerator of the present embodiment will be described in more detail.

  The piston 1 is driven by a linear motor 13 (M). The piston 1 is elastically supported by the support spring 5. Therefore, the piston 1 moves so that the relationship between its position and time draws a sine wave.

  Further, due to the movement of the piston 1, the working gas in the compression space 9 moves so that the relationship between the pressure and time draws a sine wave. The working gas compressed in the compression space 9 first releases heat from the compression space 9 as a heat exchange part for heat dissipation. Next, the compressed working gas is cooled by a regenerator 12 provided around the displacer 2. Thereafter, the compressed working gas flows from the regenerator 12 into the expansion space 10 as a heat exchange part for heat absorption.

  The working gas in the expansion space 10 is expanded by the movement of the displacer 2. The temperature of the expanded working gas decreases. The working gas in the expansion space 10 moves so that the relationship between the pressure and time draws a sine wave. The sine wave indicating the relationship between the pressure of the working gas in the expansion space 10 and time is a waveform having a predetermined phase difference with respect to the sine wave indicating the relationship between the pressure of the working gas in the compression space 9 and time. There is a waveform that changes with the same period. That is, the displacer 2 reciprocates with a predetermined phase difference with respect to the piston 1.

  The refrigeration capacity in the expansion space 10 is determined by the degree of fluctuation of the pressure of the working gas in the expansion space 10 caused by the reciprocating motion of the displacer 2. The pressure in the expansion space 10 is a relative position between the displacer 2 and the piston 1 caused by a change between the phase of the piston 1 and the phase of the displacer 2, that is, the difference between the pressure in the expansion space 10 and the pressure in the compression space 9. Fluctuates due to changes in

  The relative positional relationship between the displacer 2 and the piston 1 is determined by the mass of the displacer 2, the spring constant of the support spring 6, and the frequency of the piston 1. Further, the mass of the displacer 2 and the spring constant of the support spring 6 are determined at the time of design.

  The PWM control signal output from the microcomputer 1000 in the control device 30 to the inverter circuit 100 described later is a digital signal, that is, a pulse waveform. This pulse waveform is converted into an analog signal, that is, a sine wave in the inverter circuit 100. The frequency of this sine wave becomes the frequency of the piston 1 of the Stirling refrigerator 40.

  Note that when converting a digital signal to an analog signal, PWM is used as described above. That is, the plurality of pulses sequentially output from the microcomputer 100 gradually change in width from a small one to a large one, and after returning to a peak width, gradually return to a small one. It is configured. Thereby, an AC waveform is generated.

  Next, the microcomputer 1000 and the inverter circuit 100 in the control device 30 will be described with reference to FIG. As shown in FIG. 9, the control device 30 according to the present embodiment includes an inverter circuit 100 and a microcomputer 1000. The inverter circuit 100 has four switching elements and is connected to a linear motor M housed in the Stirling refrigerator 40, for example, in a manner as shown in FIG. The four switching elements are transistors Gu, Gx, Gv, and Gy, each of which has a flywheel diode connected between the source electrode and the drain electrode.

  As can be seen from FIG. 9, the transistor Gu and the transistor Gx are connected in series, and the transistor Gv and the transistor Gy are connected in series. Further, the transistor Gw and the transistor Gz are connected in series. The transistors Gu and Gx and the transistors Gv and Gy are connected in parallel with each other in this order.

  The linear motor 13 (M) has one terminal connected to a node between the transistor Gu and the transistor Gx, and the other terminal connected to a node between the transistor Gv and the transistor Gy.

  According to the AC power generation device of the present embodiment, microcomputer 100 outputs a PWM control signal for turning on each of transistors Gu and Gy, and outputs a PWM control signal for turning off each of transistors Gv and Gx. . Thereby, the first alternating current flows through the transistor Gu, one terminal of the linear motor M, the linear motor M, the other terminal of the linear motor M, and the transistor Gy in this order.

  Further, the microcomputer 100 outputs a PWM control signal for turning on each of the transistors Gv and Gx, and outputs a PWM control signal for turning off each of the transistors Gu and Gy. Thereby, the second AC current flows in this order through the transistor Gv, the other terminal of the linear motor M, the linear motor M, one terminal of the linear motor M, and the transistor Gx.

  A smoothing capacitor C is provided in parallel with the inverter circuit 100. A rectifier D is provided in parallel to the smoothing capacitor C. Further, an AC power supply G is provided in parallel with the rectifier D. Further, a capacitor CC for stabilizing the potential of the inverter circuit 100 is provided. Resistors R1 and R2 are provided in parallel with the capacitors C and CC between the capacitors C and CC and the inverter circuit 100. The resistor R1 and the resistor R2 are connected in series and function as a voltage dividing circuit. A node between the resistor R1 and the resistor R2 is connected to a voltage sensor of the microcomputer 1000.

  Therefore, the potential of the node between the resistor R1 and the resistor R2 is detected by the microcomputer 1000. Using the potential value, microcomputer 1000 detects the value of the AC power voltage input to inverter circuit 100 using a DC sensor. Note that a capacitor CCC is provided in parallel to the resistor R2, but the capacitor CCC is for stabilizing the potential of the node between the resistor R1 and the resistor R2.

  In the analog / digital conversion of the DC voltage sensor in the microcomputer 1000 described above, the principle of the analog / digital conversion circuit or the analog / digital conversion method described with reference to FIGS. 1, 4 and 7 is used. For example, the microcomputer 1000 can grasp the value of the DC voltage input to the inverter circuit 100 with higher accuracy. Therefore, when the DC voltage input to the inverter circuit 100 increases, the duty ratio of the transistors constituting the inverter circuit 100 is reduced, while when the DC voltage input to the inverter circuit 100 decreases, the inverter circuit Adjustment for making the AC waveform close to an ideal sine curve, such as increasing the duty ratio of the transistors constituting 100, can be performed with higher accuracy. As a result, it is possible to prevent the reciprocating motions of the piston 1 and the displacer 2 of the Stirling refrigerator 40 from being distorted due to the variation of the DC voltage input to the inverter circuit 100 for each product. That is, the reciprocating motion of the piston 1 and the displacer 2 of the Stirling refrigerator 40 can be an ideal single vibration in any product. As a result, each operation efficiency of the Stirling refrigerator 40 of the mass-produced product (for example, a refrigerator) can be increased uniformly.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

1 is a diagram for explaining an analog / digital conversion apparatus according to Embodiment 1; FIG. 3 is a diagram for explaining the principle of analog / digital conversion according to Embodiment 1. FIG. 6 is a diagram for explaining an analog / digital conversion process (1) according to the first embodiment; FIG. FIG. 6 is a diagram for explaining an analog / digital conversion apparatus according to a second embodiment. FIG. 10 is a diagram for explaining the principle of analog / digital conversion according to the second embodiment. FIG. 10 is a diagram for explaining an analog / digital conversion process (2) according to the second embodiment. FIG. 10 is a diagram for explaining a modification of the analog / digital conversion device according to the second embodiment. It is a figure for demonstrating the Stirling refrigerator of embodiment. It is a figure for demonstrating the microcomputer and inverter circuit which were mounted in the Stirling refrigerating system of embodiment. It is a figure for demonstrating the conventional analog / digital conversion circuit. It is a figure for demonstrating the principle of general analog / digital conversion.

Explanation of symbols

  D diode, Dz zener diode, VR variable resistor, M motor, 400 constant voltage circuit, 1 piston, 2 displacer, 13 (M) linear motor, 100 inverter circuit, 1000 microcomputer.

Claims (3)

A control device;
A peripheral circuit electrically connected between the control device and a power source;
The controller is
A reference voltage terminal to which a reference voltage is applied;
One and other analog / digital conversion terminals for receiving analog information;
One and other analog / digital conversion circuits for creating digital information corresponding to the analog information;
A central processing unit that performs operations using the digital information,
The peripheral circuit includes a voltage drop circuit that is connected between the one analog / digital conversion terminal and the power supply and drops the reference voltage by a predetermined drop voltage;
The one analog / digital conversion circuit receives one voltage information having a value lower than the other analog / digital conversion circuit by the predetermined drop voltage, and one output digital value corresponding to the one voltage information Output
The central processing unit uses the one output digital value, a digital value corresponding to the predetermined voltage drop stored in advance, and an output digital value corresponding to the predetermined reference voltage, as a reference. Calculate the actual value of the voltage,
The other analog / digital conversion circuit is an analog / digital conversion device that converts the analog information into the digital information using an actual value of the reference voltage. A control device;
A peripheral circuit electrically connected between the control device and a power source;
The controller is
A reference voltage terminal to which a reference voltage is applied;
One and other analog / digital conversion terminals for receiving analog information;
One and other analog / digital conversion circuits for creating digital information corresponding to the analog information;
A central processing unit that performs operations using the digital information,
The peripheral circuit includes a constant voltage circuit that is connected between the one analog / digital conversion terminal and the power supply, and applies a constant voltage smaller than the reference voltage to the one analog / digital conversion terminal. ,
The one analog / digital conversion circuit receives the information of the constant voltage, and outputs one output digital value corresponding to the information of the constant voltage,
The central processing unit uses the one output digital value, a digital value corresponding to the constant voltage stored in advance, and an output digital value corresponding to the predetermined reference voltage to calculate the reference voltage. Calculate the actual value,
The other analog / digital conversion circuit is an analog / digital conversion device that converts the analog information into the digital information using an actual value of the reference voltage. An inverter circuit that generates AC power using DC power;
A linear motor to which the AC power is supplied;
A piston that reciprocates by the linear motor;
A displacer that reciprocates due to pressure fluctuations resulting from the reciprocation of the piston;
A measurement circuit for measuring the voltage of the DC power;
An analog / digital conversion device according to claim 1 or 2,
A Stirling refrigeration system, wherein the analog voltage information of the DC power output from the measurement circuit is input to the other analog / digital conversion terminal of the analog / digital conversion device.

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