JP6583905B2 - Thermoelectric element driving device - Google Patents

Description

  The present invention relates to a thermoelectric element driving apparatus configured by joining dissimilar metals or P-type and N-type semiconductors.

  A temperature control device that can quietly cool or heat components, or both cool and heat, using the Peltier effect and the Thomson effect, which are heat transfer and exothermic endothermic phenomena that occur when current flows through the thermoelectric element Is used.

  A temperature control device using a thermoelectric element is simple in structure and can locally cool and heat, so a small cooling / heating chamber used in a narrow room of a passenger car, a CPU (central processing unit) such as a personal computer, It is used to cool electronic parts such as imaging devices for astronomical telescopes and local parts during surgery.

  Furthermore, since no sound is generated from the thermoelectric element itself during operation for a refrigerator or a thermostatic chamber in which the refrigerant is circulated, it is also used in an indoor cooling / heating chamber of a luxury hotel where quietness is important. In addition, thermoelectric elements are attracting attention as elements that are friendly to the global environment because they can suppress the discharge of environmental pollutants.

  In the Peltier effect, heat transfer proportional to the average value of the current flowing through the thermoelectric element can be obtained. The thermoelectric elements in these devices are usually driven by a pulse current controlled by PWM (Pulse Width Modulation), PDM (Pulse Density Modulation), or the like that can suppress heat generation and can be controlled accurately.

  Usually, since it is necessary to flow a large amperage current through the thermoelectric element, the thermoelectric element is driven by a pulse current to suppress heat generation in the drive circuit portion.

  As conventional techniques, for example, techniques described in Patent Documents 1 to 3 are known.

Japanese Patent Laid-Open No. 11-037600 JP-A-5-216545 JP 2012-089576 A

  However, since Joule heat generated in the thermoelectric element is proportional to the square of the effective value of the drive current, it increases in inverse proportion to the duty cycle (ON time ratio) of the pulse when the same average current is passed. Therefore, during the conventional pulse driving, the cooling effect is suppressed by self-heating. Moreover, the control precision of the thermal effect was also suppressed.

  The subject of this invention is providing the thermoelectric element drive device which can suppress the heat_generation | fever of thermoelectric element itself by suppressing the effective value of the drive current of a thermoelectric element.

In order to solve the above problems, the present invention provides a DC power supply, a thermoelectric element having one end connected to one end of the DC power supply, a coil having one end connected to one end of the DC power supply, and a thermoelectric element. A capacitor connected to both ends, a free-wheeling diode having one end connected to the other end of the coil and the other end connected to the other end of the thermoelectric element, and one end connected to the other end of the coil and one end of the free-wheeling diode The other end of the DC power source is connected to the other end, and the driving element that drives the thermoelectric element is provided, and when the driving element is shut off, the reflux diode is turned on, and when the driving element is turned on, the reflux diode is turned on. It is characterized by blocking .

  According to the present invention, it is possible to reduce the heat generation of the thermoelectric element itself by suppressing the effective value of the driving current of the thermoelectric element.

It is a circuit block diagram of the thermoelectric element drive device which concerns on Example 1 of this invention. It is operation | movement explanatory drawing which shows the current waveform of each part of the thermoelectric element drive device which concerns on Example 1 of this invention. It is a circuit block diagram of the modification of the thermoelectric element drive device which concerns on Example 1 of this invention. It is a circuit block diagram of the thermoelectric element drive device which concerns on Example 2 of this invention. It is a circuit block diagram of the thermoelectric element drive device which concerns on Example 3 of this invention. It is a circuit block diagram of the thermoelectric element drive device which concerns on Example 4 of this invention. It is a circuit block diagram of the thermoelectric element drive device which concerns on Example 5 of this invention.

  Hereinafter, a thermoelectric element driving apparatus according to an embodiment of the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a circuit configuration diagram of a thermoelectric element driving apparatus according to Embodiment 1 of the present invention. In FIG. 1, one end of a coil L, one end of a Peltier element PL, and one end of a capacitor C are connected to the positive electrode of the DC power supply Vcc. Capacitors C are connected to both ends of the Peltier element PL.

  The Peltier element PL is a thermoelectric element. This thermoelectric element is formed by joining dissimilar metals or P-type and N-type semiconductors, and converts the Peltier effect and heat energy that transfers the amount of heat according to the current into electrical energy. Produces the Seebeck effect. Heat transfer efficiency is enhanced by bringing the above-mentioned joint into close contact with a cooling / heating target object through ceramics having good thermal conductivity.

  One end of the switch SW is connected to the other end of the coil L, and the other end of the electronically controllable switch SW and the negative electrode of the DC power source Vcc are grounded. The other end of the coil L is connected to the anode of a freewheeling diode D composed of, for example, a Schottky barrier diode or a high speed diode capable of operating at high speed, and the other end of the Peltier element PL is connected to the cathode of the freewheeling diode D. .

  The switch SW constitutes a drive element composed of an electronic switch element such as a MOSFET, IGBT, or bipolar transistor that drives the Peltier element PL, and is turned on / off at a predetermined cycle by a pulse control signal such as a PWM signal, thereby causing the Peltier element PL Drive. In the figure, the other end of the switch SW and the negative electrode of the DC power supply Vcc are grounded, but it goes without saying that they are not necessarily grounded for operation. Needless to say, the polarities of the DC power supply Vcc and the free wheel diode D may be reversed.

  Next, the operation of the thus configured thermoelectric element driving apparatus according to the first embodiment will be described with reference to the current waveforms of the respective parts shown in FIG. In FIG. 2, IL is a current flowing through the coil L, Isw is a current flowing through the switch SW, Ip is a current flowing through the Peltier element PL, and Ic is a current flowing through the capacitor C.

  First, at time t0, when the switch SW is turned on by the PWM signal, a current IL flows from the DC power source Vcc to the coil L and the freewheeling diode D is reverse-biased and cut off, and the discharge current Ic from the capacitor C is changed to the Peltier element PL. Flowing into. At time t0 to t1, the current IL increases and the capacitor C is discharged by the current Ic. At this time, if the capacitance of the capacitor C is made sufficiently large, the voltage change of the capacitor C can be suppressed, and the current flowing in the Peltier element PL can be made a direct current that is maintained at a substantially constant value.

  Next, at time t1, when the switch SW is turned off by the PWM signal, the electromagnetic energy of the coil L is released and the capacitor C is charged, thereby suppressing the decrease in the direct current Ip flowing through the Peltier element PL. It is maintained at a substantially constant value. Further, since the current IL from the coil L mainly flows through the capacitor C, a substantially constant direct current Ip can be passed through the Peltier element PL.

  That is, by connecting the capacitor C in parallel to the Peltier element PL or connecting the coil L in series, the effective value is suppressed by reducing the AC component while leaving only the DC component of the drive current of the Peltier element PL. Thus, the heat generation of the thermoelectric element itself can be reduced. Further, by connecting the capacitor C in parallel to the Peltier element PL, it is possible to accurately adjust the average current of the Peltier element PL by controlling the switch SW with a pulse signal using a conventional simple control circuit.

  Further, since the other end of the switch SW and the negative electrode of the DC power source Vcc are grounded, the switch SW can be stably pulse-controlled. Further, even when the polarity of the driving elements constituting the DC power supply Vcc, the Peltier element PL, the freewheeling diode D, and the switch SW is reversed, the positive electrode of the DC power supply Vcc can be regarded as a stable ground point in terms of AC. Needless to say, the same stability can be obtained.

  FIG. 3 is a circuit configuration diagram of a modified example of the thermoelectric element driving apparatus according to Embodiment 1 of the present invention. The thermoelectric element driving apparatus according to the modification shown in FIG. 3 uses an AC power supply Vac and a full-wave rectifier circuit including diodes D1 to D4 instead of the DC power supply Vcc of the thermoelectric element driving apparatus shown in FIG. Features. Needless to say, if the full-wave rectifier circuit is a rectifier circuit, it can be replaced with a half-wave rectifier circuit or the like.

  The anode of the diode D1 is connected to one end of the AC power supply Vac and the cathode of the diode D4, and the cathode of the diode D1 is connected to the cathode of the diode D3 and one end of the coil L. The anode of the diode D2 is connected to one end of the switch SW and the anode of the diode D4. The cathode of the diode D2 is connected to the other end of the AC power supply Vac and the anode of the diode D3.

  According to the thermoelectric element driving device configured as described above, the AC voltage of the AC power supply Vac is full-wave rectified by the diodes D1 to D4, and the rectified voltage is supplied to the series circuit of the coil L and the switch SW. The operations of the coil L, the Peltier element PL, the capacitor C, and the free wheeling diode D are the same as those shown in FIG.

  In the present embodiment, the rectified voltage of the AC power supply Vac is applied to the coil L without being affected by the charging voltage of the capacitor C even at the timing when the AC voltage of the AC power supply Vac drops to near 0 V, thereby increasing the rectified voltage amplitude. Since the tracked input current and the Peltier device driving current can be generated, the power factor of the circuit can be greatly improved. Further, in a thermoelectric element driving apparatus that uses an AC power supply through a conventional DC stabilized power supply circuit, the AC power supply current generally flows only when the smoothing capacitor is charged. However, in the present embodiment, since it can always flow with a waveform that is substantially proportional to the power supply voltage, the harmonic component of the input current can be greatly reduced and the high frequency noise generated from the thermoelectric element driving device can also be greatly suppressed. . Furthermore, since the thermoelectric element can be driven directly from the AC power supply without using the DC stabilized power supply circuit, a small and inexpensive thermoelectric element driving device with high power efficiency can be provided.

  FIG. 4 is a circuit configuration diagram of a thermoelectric element driving apparatus according to Embodiment 2 of the present invention. In FIG. 4, one end of a Peltier element PL, one end of a capacitor C, and the cathode of a free-wheeling diode D are connected to the positive electrode of the DC power supply Vcc. Capacitors C are connected to both ends of the Peltier element PL.

  One end of the coil L is connected to the other end of the Peltier element PL, and the other end of the coil L is connected to the anode of the freewheeling diode D and one end of the switch SW. The other end of the switch SW and the negative electrode of the DC power source Vcc are grounded.

  According to the thermoelectric element driving apparatus according to the second embodiment configured as described above, when the switch SW is turned on by the PWM signal, a current flows to the coil L through the Peltier element PL connected in series from the DC power source Vcc. A current also flows through the capacitor C.

  Next, when the switch SW is turned off by the PWM signal, the current component that fluctuates in the capacitor C connected in parallel is bypassed and a DC voltage is supplied from the capacitor C. Therefore, a constant DC current is supplied to the Peltier element PL. Flowing. At this time, a current flows from the coil L to the parallel circuit of the capacitor C and the Peltier element PL via the return diode D, and electromagnetic energy is released.

  Here, a coil L having such a characteristic that a current having a continuous value in time flows through the element itself is always connected in series to the Peltier element PL. Therefore, although the capacitor C has the effect of flattening the applied voltage to the Peltier element PL and flowing a constant DC current, the inductance value of the coil L can be obtained without removing the capacitor C and connecting it in parallel to the Peltier element PL. By setting a large value, a substantially constant DC current can be passed through the Peltier element PL.

  By connecting the coil L in series with the Peltier element PL, a pulse drive current whose average value is accurately controlled can be passed through the Peltier element PL, and the power consumption of the Peltier element PL and the switch SW can be reduced. .

  In the thermoelectric element driving apparatus according to the present embodiment, both cooling and heating of the object can be performed. FIG. 5 is a circuit configuration diagram of a thermoelectric element driving apparatus according to Embodiment 3 of the present invention. 5 further includes a first switch SW1, a second switch SW2, a third switch SW3, a second switch SW3, a third switch SW3, a second switch SW3, and a second switch SW3. When the four switch SW4 is provided and the Peltier element PL is used for heat, the coil L is not connected in series to the Peltier element PL. The first switch SW1, the second switch SW2, the third switch SW3, and the fourth switch SW4 may be configured as manual switches or electronically controllable switches.

  The first switch SW1 is connected in series to the capacitor C, and is turned on when the Peltier element PL is used for cooling, and turned off when the Peltier element PL is used for heating. Similarly to the embodiment shown in FIG. 4, the capacitor C can be omitted.

  The second switch SW2 is connected in parallel to the coil L and is turned off when the Peltier element PL is used for cooling, and turned on when the Peltier element PL is used for heating.

  The third switch SW3 and the fourth switch SW4 correspond to the switching unit of the present invention, and the direction of current that flows when the Peltier element PL is used for heating is compared to the direction of current that flows when the Peltier element PL is used for cooling. It is a switch that reverses.

  The third switch SW3 has a common terminal a1, a cooling switching terminal b1, and a thermal switching terminal c1. When the Peltier element PL is used for cooling, the third switch SW3 is switched to the cooling switching terminal b1, and the Peltier element PL is used for heating. Is switched to the thermal switching terminal c1.

  The common terminal a1 is connected to one end of the Peltier element PL, and the cooling switching terminal b1 is connected to the positive electrode of the DC power supply Vcc and one end of the first switch SW1. The thermal switching terminal c1 is connected to one end of the switch SW and the other end of the coil L.

  The fourth switch SW4 has a common terminal a2, a cooling switching terminal b2, and a thermal switching terminal c2. When the Peltier element PL is used for cooling, it is switched to the cooling switching terminal b2, and the Peltier element PL is used for heating. Is switched to the thermal switching terminal c2.

  The common terminal a2 is connected to the other end of the Peltier element PL, and the cooling switching terminal b2 is connected to one end of the coil L, one end of the second switch SW2, and one end of the capacitor C. The thermal switching terminal c2 is connected to the positive electrode of the DC power supply Vcc.

  The operation of the thus configured thermoelectric element driving apparatus according to the third embodiment will be described with reference to FIG. The switch SW is electronically turned on / off.

  First, when the Peltier element PL is used for cooling an object, the first switch SW1 is turned on, the second switch SW2 is turned off, the third switch SW3 is switched to the cooling switching terminal b1, and the fourth switch SW4 is cooled. Switch to the switching terminal b2. When the switch SW is on, the coil L is connected in series with the Peltier element PL.

  Then, a capacitor C is connected in parallel to the Peltier element PL. At this time, a current flows from the coil L to the Peltier element PL via the third switch SW3, the Peltier element PL, and the fourth switch SW4, and the cooling operation is continued. A current also flows through the capacitor C. That is, when the object is cooled, the driving current of the Peltier element PL is flattened to suppress the effective value, thereby reducing the power consumption of the element itself and improving the cooling effect. The flatness of the drive current can be improved by connecting the capacitor C in parallel to the Peltier element PL via the first switch SW1, but the capacitor C is eliminated as described above by sufficiently increasing the inductance value of the coil L. You can also.

  Next, when the Peltier element PL is used to heat the object, the first switch SW1 is turned off to disconnect the capacitor C, the second switch SW2 is turned on to short-circuit both ends of the coil L, and the coil L So that no current flows in Further, the third switch SW3 is switched to the thermal switching terminal c1, and the fourth switch SW4 is switched to the thermal switching terminal c2.

  Then, the capacitor C is disconnected from the Peltier element PL. At this time, a current flows from the DC power source Vcc to the switch SW via the fourth switch SW4, the Peltier element PL, and the third switch SW3, and the Peltier element PL performs a heating operation. That is, when the object is heated, the heating efficiency of the Peltier element PL can be improved by increasing the unevenness of the drive current to increase the effective value without increasing the heat generation of the element itself.

  FIG. 6 is a circuit configuration diagram of a thermoelectric element driving apparatus according to Embodiment 4 of the present invention. The thermoelectric element driving apparatus according to the fourth embodiment shown in FIG. 6 is characterized in that the first switch SW1 and the second switch SW2 are deleted from the thermoelectric element driving apparatus according to the third embodiment shown in FIG.

  The operation of the thus configured thermoelectric element driving apparatus according to the fourth embodiment will be described with reference to FIG.

  First, when the Peltier element PL is used for cooling an object, the third switch SW3 is switched to the cooling switching terminal b1, and the fourth switch SW4 is switched to the cooling switching terminal b2.

  Then, the coil L is connected in series with the Peltier element PL. At this time, the flattened drive current flows from the coil L through the third switch SW3, the Peltier element PL, and the fourth switch SW4 from the DC power source Vcc, and the Peltier element PL is cooled. That is, when the object is cooled, the driving current of the Peltier element PL is flattened to suppress the effective value, thereby reducing the power consumption of the element itself and improving the cooling effect.

  Next, when the Peltier element PL is used for the temperature of the object, the third switch SW3 is switched to the temperature switching terminal c1, and the fourth switch SW4 is switched to the temperature switching terminal c2.

  Then, the coil L is disconnected from the Peltier element PL. At this time, the drive current pulse-controlled by the switch SW flows from the DC power source Vcc through the fourth switch SW4, the Peltier element PL, and the third switch SW3, and the Peltier element PL is operated by heat. That is, when the object is heated, the efficiency can be improved by increasing the unevenness of the drive current of the Peltier element PL to increase the effective value and increasing the heat generation of the element itself.

  In addition, this invention is not limited to the thermoelectric element drive device which concerns on Example 1 thru | or 4 mentioned above. In the thermoelectric element driving apparatus according to the third embodiment shown in FIG. 5 and the thermoelectric element driving apparatus according to the fourth embodiment shown in FIG. 6, the switches SW1 to SW1 are compared with the thermoelectric element driving apparatus according to the second embodiment shown in FIG. By providing SW4, the coil L is connected in series when the Peltier element PL is used for cooling, and the influence of the coil L is eliminated when the Peltier element PL is used for heating. The embodiment shown in FIG. 6 is realized at a lower cost by reducing the number of switches compared to the embodiment shown in FIG.

  For example, by providing switches corresponding to the switches SW1 to SW4 to the thermoelectric element driving apparatus according to the first embodiment shown in FIG. 1, when the Peltier element PL is used for cooling, a capacitor C is connected in parallel to the Peltier element PL. When the Peltier element PL is used for heat, the capacitor C may be separated from the Peltier element PL. A specific embodiment is shown in FIG.

  Also in the embodiment shown in FIG. 4, when the Peltier element PL is used for cooling, the coil L is connected, and when the Peltier element PL is used for heating, the coil L is short-circuited, and the free wheel diode D and the capacitor C are connected. It may be deleted.

  In the embodiment of the present invention, it goes without saying that the same effect can be obtained even when the polarities of the DC power supply Vcc, the Peltier element PL, the free wheel diode D, and the drive elements constituting the switch SW are reversed.

  The present invention can be used for a temperature control device or the like.

PL thermoelectric element Vcc DC power supply C capacitor L coil SW switch SW1 first switch SW2 second switch SW3 third switch SW4 fourth switch D freewheeling diodes D1 to D4 diode Vac AC power supply

Claims (6)

DC power supply,
A thermoelectric element having one end connected to one end of the DC power supply;
A coil having one end connected to one end of the DC power supply;
A capacitor connected to both ends of the thermoelectric element;
A reflux diode having one end connected to the other end of the coil and the other end connected to the other end of the thermoelectric element;
One end is connected to the other end of the coil and one end of the reflux diode, the other end is connected to the other end of the DC power source, and a driving element for driving the thermoelectric element ,
The thermoelectric element driving device characterized in that the reflux diode is turned on when the drive element is turned off, and the return diode is turned off when the drive element is turned on . The thermoelectric element is provided between the thermoelectric element and the capacitor. When the thermoelectric element is used for cooling, the capacitor is connected in parallel to the thermoelectric element. When the thermoelectric element is used for heating, the capacitor is removed from the thermoelectric element. The thermoelectric element driving device according to claim 1, further comprising a switching unit that electrically separates the switching element. The DC power source is an AC power source,
A rectifier circuit that rectifies an AC voltage of the AC power supply and has one end of a rectification output terminal connected to one end of the thermoelectric element ;
Thermoelectric element driving device according to claim 1 or 2, characterized in that it comprises a. DC power supply,
A thermoelectric element having one end connected to one end of the DC power supply;
A coil having one end connected to the other end of the thermoelectric element;
A free-wheeling diode having one end connected to the other end of the coil and the other end connected to one end of the thermoelectric element;
One end is connected to the other end of the coil and one end of the reflux diode, the other end is connected to the other end of the DC power source, and a driving element for driving the thermoelectric element,
A capacitor connected to both ends of the thermoelectric element;
The thermoelectric element is provided between the thermoelectric element and the capacitor. When the thermoelectric element is used for cooling, the capacitor is connected in parallel to the thermoelectric element. When the thermoelectric element is used for heating, the capacitor is removed from the thermoelectric element. A thermoelectric element driving device comprising: a switching unit for electrically disconnecting . The thermoelectric element driving device according to any one of claims 1 to 4 , wherein the other end of the DC power source and the other end of the driving element are grounded in an alternating manner. Is connected in parallel to the coil, any one of claims 1 to 5, characterized in that off when using the thermoelectric element for cooling comprises a first switch which is turned on when using the thermoelectric element in thermal The thermoelectric element driving device according to claim 1.

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