JP3654635B2 - Thermoelectric power generation control device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a thermoelectric generator control device that boosts and controls an electromotive force from a thermoelectric generator such as a thermocouple.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, there is known a thermoelectric generation control device that boosts an electromotive force of a thermocouple heated by a burner with a booster circuit and drives an actuator such as a fan motor with the boosted output voltage.
As an example of application of such a thermoelectric generation control device to an infrared heater, an infrared heater with a fan that performs heating by hot air from a blower fan driven by thermoelectric generation in addition to radiant heat from a red-hot plate type gas burner is known. .
[0003]
[Problems to be solved by the invention]
However, since the energy generated by the thermocouple is unstable, the boosted voltage is also unstable. Moreover, the boosted output voltage is affected by the size of the load, and the output is not stable. For this reason, the stable operation | movement of loads, such as a ventilation fan, was not obtained.
The thermoelectric power generation control device of the present invention has an object to solve the above-described problems and to control the electric power generated by the thermoelectric generator to stably supply it to a load.
[0004]
[Means for Solving the Problems]
  The thermoelectric power generation control device according to claim 1 of the present invention for solving the above-mentioned problems is provided.
  A thermoelectric generator that generates electricity by heat;
  A booster circuit for inducing a voltage in the coil by turning on and off the switching element to boost the electromotive force input from the thermoelectric generator;
  A load energizing circuit for energizing the load using the boosted power as a power source;
  Voltage detection means for detecting the power supply voltage of the load;
  A step-up efficiency control circuit for adjusting the step-up efficiency by controlling the switching element so that the output voltage of the step-up circuit, which is a detection voltage of the voltage detection means, is maximized;,
A second booster circuit for further boosting the output voltage boosted by the booster circuit;
The power boosted by the second booster circuit is used as a power source for the boosting efficiency control circuitThis is the gist.
[0005]
  Moreover, the thermoelectric generation control device according to claim 2 of the present invention is the thermoelectric generation control device according to claim 1,
The load is a motor,
A pseudo load that consumes the boosted electromotive force instead of the motor is provided, and before the motor is driven, the pseudo load is energized so that the power supply voltage of the pseudo load is maximized. Temporarily adjustedThis is the gist.
[0006]
  A thermoelectric generator control device according to claim 3 of the present invention is
A thermoelectric generator that generates electricity by heat;
A booster circuit for inducing a voltage in the coil by turning on and off the switching element to boost the electromotive force input from the thermoelectric generator;
A load energizing circuit for energizing the motor using the boosted power as a power source;
Voltage detection means for detecting the power supply voltage of the motor;
A step-up efficiency control circuit for adjusting the step-up efficiency by controlling the switching element so that the output voltage of the step-up circuit, which is the detection voltage of the voltage detection means, is maximized;
A pseudo load that consumes electric power obtained by boosting the electromotive force instead of the motor;
Before driving the motor, the boosting efficiency is temporarily adjusted by energizing the pseudo load and maximizing the power supply voltage of the pseudo load.This is the gist.
[0011]
  In the thermoelectric generation control device according to claim 1 of the present invention having the above-described configuration, a voltage is induced in the coil by turning on and off the switching element of the booster circuit, the electromotive force generated by the thermoelectric generator is boosted, and the boosted voltage is increased. The voltage is detected, the switching element is controlled so that the detected voltage becomes maximum, and the boosted power is stably supplied to the load. When this detection voltage, that is, the output voltage of the booster circuit is maximum, the boosting efficiency is also maximum.
  The boosting efficiency is a ratio (in this case, 2.4 W / 3 W = 80%) of electric power (eg, 2.4 V at 6 V, 0.4 A) obtained by boosting from a power source (eg, 3 V at 1 A). is there.
  Further, the electromotive force is boosted by the booster circuit and used as a power source for the load, and the output voltage boosted by the booster circuit is further boosted by the second booster circuit and used as the power source for the boosting efficiency control circuit.
For example, when boosting from 1 V to 3 V, when boosting from 1 V to 3 V at a stretch, it is possible that the boosting difference is too large and can only be boosted to about 2.7 V. On the other hand, when the booster circuit first boosts the voltage from 1V to 2.6V with a margin, and then the second booster circuit boosts the boosted 2.6V to 3V, it is surely desired. The voltage can be boosted to a voltage.
By the way, the voltage of the control signal from the boosting efficiency control circuit and the on-resistance of the boosting circuit are inversely proportional to each other. The larger the signal voltage, the smaller the on-resistance, and the lower the energy loss during boosting and the higher the boosting efficiency. Therefore, by raising the power supply voltage of the boosting efficiency control circuit to the second boosting circuit, the operation of the boosting efficiency control circuit is stabilized and the boosting efficiency can be adjusted reliably.
[0012]
  A thermoelectric generator control device according to claim 2 of the present invention isBefore driving the motor, the boosted power is applied to a pseudo load such as a resistor instead of the motor. During this time, the boosting efficiency is temporarily adjusted so that the power supply voltage at the pseudo load is maximized, so that the boosting efficiency is adjusted to some extent even if the energization to the pseudo load is stopped and the motor is driven. For this reason, the output voltage does not drop abruptly when the motor is energized, and the motor is prevented from rotating.
[0013]
  A thermoelectric generator control device according to claim 3 of the present invention isA voltage is induced in the coil by turning on and off the switching element of the booster circuit, the electromotive force generated by the thermoelectric generator is boosted, the boosted voltage is detected, and the switching element is controlled so that the detected voltage becomes maximum Thus, the boosted power is stably supplied to the load. When this detection voltage, that is, the output voltage of the booster circuit is maximum, the boosting efficiency is also maximum.
The boosting efficiency is a ratio (in this case, 2.4 W / 3 W = 80%) of electric power (eg, 2.4 V at 6 V, 0.4 A) obtained by boosting from a power source (eg, 3 V at 1 A). is there.
Furthermore, before the motor is driven, the boosted power is applied to a pseudo load such as a resistor instead of the motor. During this time, the boosting efficiency is temporarily adjusted so that the power supply voltage at the pseudo load is maximized, so that the boosting efficiency is adjusted to some extent even if the energization to the pseudo load is stopped and the motor is driven. For this reason, the output voltage does not drop abruptly when the motor is energized, and the motor is prevented from rotating.
[0018]
DETAILED DESCRIPTION OF THE INVENTION
In order to further clarify the configuration and operation of the present invention described above, a preferred embodiment of the thermoelectric generator control apparatus of the present invention will be described below.
[0019]
A thermoelectric generator control device as one embodiment of the present invention will be described with reference to FIGS.
FIG. 2 is a schematic cross-sectional view of an infrared heater 1 with a fan (hereinafter simply referred to as a heater 1).
The stove 1 includes a red hot plate type burner 4 facing the radiation opening 2 in a main body case 3 having a radiation opening 2 provided on the front surface.
[0020]
The burner 4 includes a burner body 6 that forms a mixing chamber of fuel gas and primary air, and a ceramic combustion plate 7 provided with a plurality of flame holes that are attached to the burner body 6. A fuel gas and primary air sucked from a suction hole (not shown) are well mixed in the burner body 6, and the air-fuel mixture is ejected from the flame hole of the combustion plate 7 and is surfaced on the combustion plate 7. Burn.
[0021]
The burner body 6 is divided into upper and lower burner bodies 13 and 15 and divided into upper and lower stages. And the combustion plate 7 is a structure provided by two each in the upper burner main body 13 and the lower burner main body 15, and it burns only on the two surfaces provided in the high-burning power setting which burns on the whole surface, and the lower burner main body 15 Two types of thermal power switching can be performed.
[0022]
A fan 9 is provided at the bottom of the main body case 3 to send the combustion gas of the burner 4 from a hot air outlet 8 provided at the lower front of the main body case 3. Behind the burner 4, there is provided a hot air intake passage 11 having a combustion gas suction port 10 in the vicinity of the upper part of the burner 4, and for guiding a mixture (hot air) of the combustion gas and room temperature air to the fan 9. The fan 9 and the hot air outlet 8 are communicated with each other by a hot air delivery passage 12.
[0023]
In addition, a room temperature air inlet 16 is opened at a position substantially opposite to the combustion gas inlet 10 on the back side of the appliance, and communicates with the hot air intake passage 11. Therefore, when the fan 9 is driven, combustion gas is sucked from the combustion gas suction port 10, indoor air is sucked from the room temperature air suction port 16, is mixed in the hot air intake passage 11 and the hot air delivery passage 12, and is burned A mixture of gas and external air is sent out from the hot air outlet 8 as an appropriate hot air.
[0024]
In addition, a plurality of guard rods 14 are provided at the radiation opening 2 and the hot air outlet 8 so that a user's hand does not enter the instrument body.
Further, series-type thermocouples 35 arranged in two rows in the front and rear are provided facing the front surface of the combustion surface 5 of the burner 4, and the electric power obtained by the thermocouple 35 is used as a power source for the motor 38 of the fan 9. It is done. In addition, on the left and right sides of the fan 9, a thermoelectric generator control device 30 and a dry battery 32 for controlling power generation by the thermocouple 35 are provided (broken line in FIG. 2).
[0025]
A DC brushless motor is used as the motor 38 of the fan 9. This is because the brush motor is a mechanical contact type and is likely to be worn and has low durability. The brushless motor 38 includes an IC 38b, which is an integrated circuit for controlling the rotation of the motor 38, and switches the switching of the IC transistors in a short cycle.
[0026]
As shown in FIG. 1, the thermoelectric generator control device 30 mainly includes a controller 31, a dry battery 32, an ignition switch 33, a power supply circuit 34, a thermocouple 35, a first booster circuit 36, a second booster circuit 37, The configuration and operation of the load drive circuit 39 will be described first. In addition, the code | symbol CN in a figure shows a connector.
[0027]
The controller 31 includes a microcomputer as a main part and performs thermoelectric generation control and motor drive control. The operating voltage of the controller 31 is 3V, and the withstand voltage is 5.5V.
The ignition switch 33 is a connection switch between the dry battery 32 and the power supply circuit 34 and is turned on in conjunction with the ignition operation of the ignition lever.
The thermocouple 35 is provided near the burner 4 of the stove 1 and is heated by a flame to generate electric power with an electromotive force of about 1 V. This electric power is used as a power source for the controller 31 and the motor 38.
[0028]
The first booster circuit 36 is a DC / DC converter that boosts the electromotive force generated by the thermocouple 35, and the power (voltage is VCC2) is supplied to the winding 38 a of the motor 38 to drive the motor 38.
The first booster circuit 36 includes an FET 1 (switching element) that is turned on / off by a pulse signal from the output port c of the controller 31, an electrolytic capacitor that reduces the impedance at the time of discharging of the coil L2 and the coil L2 that induces a voltage by turning on / off the FET1 C3, an electrolytic capacitor C4 for storing electric charge, and a Schottky barrier diode D3 for preventing current from flowing from the boosted power source (electrolytic capacitor C4 or electrolytic capacitor C7 described later) to the first booster circuit 36 side.
[0029]
In addition, the Schottky barrier diode D3 has a small voltage drop of 0.2 to 0.3 V, suppresses the power consumption of this diode to the minimum, and can effectively supply the generated power to the load.
[0030]
In the first booster circuit 36 having such a configuration, the controller 31 determines that the electromotive force of the thermocouple 35 has reached a predetermined value after 3 seconds from the ignition operation (the ON operation of the ignition switch 33). A pulse signal whose frequency and duty ratio are adjusted is transmitted to the FET 1, and the FET 1 is turned on and off by the pulse signal, thereby inducing a voltage in the coil L 2 to boost the input voltage (1 V) from the thermocouple 35. Store energy. The frequency and duty ratio adjustment control will be described later in detail.
[0031]
When FET1 is on, the electromotive force of the thermocouple 35 causes a current to flow through the coil L2. When the FET 1 is turned off, the voltage rises in an attempt to keep the current flowing due to the nature of the coil L2, and the current passes through the connection point A between the first booster circuit 36 and the power supply circuit 34 to drive the second booster circuit 37 and the load drive. Flows to circuit 39. This current is used as a power source from the load drive circuit 39 to the winding 38a of the motor 38 (this applied voltage is VCC2).
Since the boosted electric power is consumed by the motor 38 and a pseudo load 40 of the load driving circuit 39 described later, the output voltage VCC2 of the first boosting circuit 36 becomes 2.6V on average. The controller 31 detects the voltage from the input port b.
[0032]
The second booster circuit 37 is a DC / DC converter that boosts the output voltage (2.6 V) boosted by the first booster circuit 36 to a predetermined voltage (3 V), and is a second booster that incorporates an FET serving as a switching element. An IC 37a that is an integrated circuit dedicated to the circuit 37, a coil L1, an electrolytic capacitor C2, and a diode D2 are provided.
The second booster circuit 37 performs on / off operation of the FET of the IC 37a by a pulse signal, thereby inducing a voltage in the coil L1, and the input voltage from the power supply circuit 34 and the first booster circuit 36 described later is set to VDD (3V). The voltage is boosted to the IC 38b of the motor 38 (required operating voltage is 3V) and supplied to the power supply port d of the controller 31 as a power source.
[0033]
Thus, the power supply of the controller 31 uses VDD (output of the second booster circuit 37) without using VCC2. This is because when VCC2 is used, the applied voltage becomes unstable under the influence of the load (required power) of the winding 38a of the motor 38. In addition, from VCC2, a voltage necessary for driving the first booster circuit 36 cannot be obtained in the initial stage.
[0034]
The voltage VDD of the IC 37a of the second booster circuit 37 is connected only to a light load (0.3 mW at 3V, 0.1 mA) of the controller 31 and the IC 38b of the motor 38. stable. On the other hand, since the output voltage VCC2 of the first booster circuit 36 is connected to a heavy load (usually 2.6V, 416 mW at 160 mA) of the motor 38, the change in boost becomes large and unstable each time it is turned on / off.
As described above, since the applied voltage is divided between the motor 38 and the controller 31, an unstable voltage is not applied to the controller 31 that controls the control, and the control can be performed normally.
[0035]
The FET 1 of the first booster circuit 36 uses a power MOSFET and can pass a large current. However, the IC 37a of the second booster circuit 37 cannot flow a current as large as that of the FET 1, so that the winding of the motor 38 can be performed. It is not suitable for driving a large load such as the line 38a, and is used for a booster device for supplying power to a lightly loaded component such as the controller 31 or the IC 38b of the motor 38.
[0036]
When the load that consumes the power from the first booster circuit 36 is large, the output voltage VCC2 of the first booster circuit 36 is small, so the voltage Vb of the input port b is also low, and there is no fear of failure of the controller 31.
On the other hand, when the load is small, the output voltage VCC2 of the first booster circuit 36 is about 10V, so that the voltage Vb of the input port b becomes too high and the controller 31 may break down. Since the input voltage is divided in half by R5 and R6 (each resistance value is equal), failure can be prevented.
[0037]
In addition, in order to prevent a failure due to an overvoltage of the controller 31, the input port b (voltage detection unit) is provided with a diode D4 for limiting the voltage Vb applied to the input port b, and is connected to VDD via the diode D4. The Since the voltage drop of the diode D4 is as small as about 0.7V, even if the electromotive force boosted by the first booster circuit 36 becomes very large, the maximum value of the voltage Vb of the input port b is “VDD (3V ) + 0.7V ”, that is, 3.7V, there is no possibility that the controller 31 will break down.
[0038]
In the electromotive force generated by the thermocouple 35, the voltage necessary for starting the motor 38 cannot be obtained. Therefore, it is necessary to boost the electromotive force. To this end, the controller 31 that operates the first booster circuit 36 is used. Must supply power. As the power source, a dry battery 32 (voltage VCC1 is 1.5 V) is used.
[0039]
When the thermocouple 35 generates an electromotive force of a predetermined value or more after a while after ignition, the electric power for the controller 31 is covered by the electromotive force, so that the power supply from the dry battery 32 to the controller 31 can be stopped.
The power supply circuit 34 is a circuit that cuts off the power supply and switches to the power supply from the thermocouple 35, and is controlled by the controller 31.
[0040]
The power supply circuit 34 includes an electrolytic capacitor C1, an electrolytic capacitor C1, and an emitter of the transistor Q1, which are connected to the bases of the transistor Q1 and the transistor Q1 that open and close the supply path of the dry battery power supply to the second booster circuit 37 via the limiting resistor R2. Are connected to the output port a of the controller 31 and to the collector of the digital transistor DT1 and transistor Q1 connected between the limit resistor R2 and the electrolytic capacitor C1. A Zener diode ZD1 is provided.
[0041]
R1 is a limiting resistor for preventing overcurrent during discharging, and R2 is a limiting resistor for preventing overcurrent during charging. In addition, the Zener diode ZD1 prevents the voltage applied to the controller 31 from exceeding its withstand voltage 5.5V. The diode D1 is provided to discharge the electric charge accumulated in the electrolytic capacitor C1 when the ignition switch 33 is turned off, so that the electrolytic capacitor C1 can be used as a timer (described later) at the next ignition.
[0042]
In the power supply circuit 34, when the ignition switch 33 is turned on by an ignition operation, the current from the dry battery 32 flows from the emitter to the base of the transistor Q1, and the transistor Q1 is turned on. This current flows to the limiting resistor R2 and the electrolytic capacitor C1.
Along with the ON operation of the transistor Q1, the current flows from the emitter to the collector and the second booster circuit 37, boosted from 1.5V to 3V (VDD), and this output voltage VDD is used as the power supply for the controller 31. .
[0043]
When about 10 seconds elapse after the ignition switch 33 is turned on, the electric charge of the electrolytic capacitor C1 is accumulated, no current flows through the electrolytic capacitor C1, and the transistor Q1 is turned off. Here, the electrolytic capacitor C1 functions as a timer.
[0044]
Next, the load drive circuit 39 will be described.
The load drive circuit 39 includes a pseudo load 40 including resistors R7 and R8, a digital transistor DT2 that controls energization of the pseudo load 40 by a signal from the output port e of the controller 31, and a signal from the output port f of the controller 31. FET 2 for driving and controlling the motor 38, a reflux diode D5 when the motor 38 is stopped, a ceramic capacitor C8, an electrolytic capacitor C7, and a resistor R10 for turning off the FET 2.
[0045]
The pseudo load 40 is supplied with the boosted power until the time for starting the motor 38 is reached, that is, until the electromotive force from the thermocouple 35 is stabilized and the electric capacitors C4 and C7 are considered to have accumulated electric charges. Instead, it is energized and is in a non-energized state while the motor 38 is driven. The pseudo load 40 is slightly lighter than the load resistance when the motor 38 rotates.
[0046]
Next, boosting efficiency adjustment control in the first boosting circuit 36 performed by the controller 31 will be described with reference to the flowcharts of FIGS.
As described above, the voltage of the control signal from the controller 31 to the FET 1 and the on-resistance of the booster circuit (resistance between the drain and the source of the FET 1) are inversely proportional to each other. Energy loss during boosting is reduced and boosting efficiency is increased. Therefore, here, the voltage is controlled to increase.
[0047]
First, when the ignition switch 33 is turned on in conjunction with the ignition operation, the control of the boosting efficiency is started. As shown in FIG. 3, as an initial setting, the switching frequency is set to 6 kHz, the duty ratio (the ratio of the ON time in one cycle) is set to 70% (S1), and the frequency change code indicating the increase / decrease when adjusting the frequency Is changed to +, and the duty ratio change sign indicating increase / decrease when adjusting the duty ratio is also changed to + (S2).
Wait until 3 seconds have elapsed since the ignition switch 33 was turned on (S3), and after 3 seconds, frequency adjustment processing (S4) and duty ratio adjustment processing (S14) are repeated so that the output voltage reaches a peak. .
[0048]
FIG. 4 shows frequency adjustment control.
First, the current VCC2 detected at the input port b is stored as V1 (S5). Since VCC2 is divided in half by resistors R5 and R6, for example, when 1.5V is detected at input port b, VCC2 at that time is 3.0V.
When the frequency change code is +, 0.25 kHz is added to the frequency (here, 6 kHz), and when the frequency change code is-, 0.25 kHz is subtracted from the frequency (S6).
Wait until 3 seconds have passed since the frequency change (S7), and after 3 seconds, assume that the voltage has stabilized and detect the current VCC2 as V2 at the input port b (S8).
[0049]
The voltage V1 before the frequency change and the voltage V2 after the change are compared (S9), and it is determined whether or not the voltage V2 is 3.5 V or less (S10, S13).
The reason why the determination value is 3.5 V is that the upper limit of the output voltage VDD of the second booster circuit 37 is set to about 3 V. As a result, the voltage V2 sets the input voltage of the second booster circuit 37 to 3.4 V. (Diode D2 voltage drop 0.4V + VDD) is not extremely exceeded.
If the voltage V2 exceeds the voltage V1 (S9: YES), it can be seen that the voltage has been boosted by changing the frequency, that is, the boosting efficiency has increased.
At this time, if the voltage V2 exceeds 3.5V (S10: NO), in order to prevent the controller 31 (withstand voltage 5.5V) from being damaged due to excessive boosting, the frequency change code is set to the opposite sign to that of this time. (S12), the pressure is stepped down when the process returns to step 6 next time. That is, + → − and − → +.
[0050]
On the other hand, when the voltage V2 is 3.5 V or less (S10: YES), the frequency change code is kept the same as this time (S11) to return to the maximum output voltage, and the next step 6 is returned to. The pressure is further increased at the time.
Then, the process proceeds to a subroutine for adjusting the duty ratio.
[0051]
In step 9, if the voltage V2 is equal to or lower than the voltage V1 (S9: NO), it is found that the voltage has been stepped down by changing the frequency, that is, the step-up efficiency has decreased. At this time, if the voltage V2 exceeds 3.5V (S13: NO), the frequency change code remains the same as this time in order to further reduce the controller 31 (withstand voltage 5.5V) so as not to fail ( S11).
On the other hand, if the voltage V2 is 3.5 V or less (S13: YES), in order to boost the output voltage so as to maximize, the frequency change code is changed to a code opposite to this time (S12).
Then, the process proceeds to a subroutine for adjusting the duty ratio.
[0052]
FIG. 5 shows duty ratio adjustment control.
First, the current voltage V1 is stored at the input port b (S15). When the duty ratio change code is +, 2% is added to the duty ratio (70% here), and when the duty ratio change code is-. Subtracts 2% from the duty ratio (S16).
It waits until 3 seconds elapse from the change of the duty ratio (S17), and after 3 seconds elapses, the voltage is considered stable and the current voltage V2 is detected (S18).
[0053]
The voltage V1 before the duty ratio change and the voltage V2 after the change are compared (S19), and it is determined whether or not the voltage V2 is 3.5 V or less (S20, S23).
If the voltage V2 exceeds the voltage V1 (S19: YES), it can be seen that the boosting efficiency is increased by changing the duty ratio.
At this time, if the voltage V2 is 3.5V or less (S20: YES), in order to further boost the voltage, the duty ratio change code is kept the same as this time (S21), and if the voltage V2 exceeds 3.5V (S20). : NO), in order not to boost the pressure any more, the duty ratio change code is changed to the opposite sign (S22), and the process returns to the subroutine for adjusting the frequency.
[0054]
In step 19, if the voltage V2 is equal to or lower than the voltage V1 (S19: NO), it can be seen that the boosting efficiency is reduced by changing the duty ratio. At this time, if the voltage V2 is 3.5 V or less (S23: YES), the duty ratio change code is changed to a code opposite to this time in order to boost the voltage (S22).
On the other hand, if the voltage V2 exceeds 3.5V (S23: NO), the duty ratio change code remains the same as this time in order to further step down the controller 31 (withstand voltage 5.5V) so as not to fail ( S21).
Then, the process returns to the subroutine for adjusting the frequency.
As shown in FIG. 3, by alternately repeating the frequency adjustment (S4) and the duty ratio adjustment (S14), the output voltage approaches the maximum peak, and the boosting efficiency is improved.
Moreover, since the output voltage does not exceed 3.5V, failure of the controller 31 can be prevented.
For example, when the required power of the load is small, the load can be driven without forcibly increasing the boosting efficiency. On the other hand, when the required power of the load is large, it is necessary to increase the boosting efficiency, but the upper limit value 3.5V of the output voltage VCC2 of the first booster circuit 36 is set so as not to boost the controller 31 so as to cause a failure. doing.
[0055]
Next, control of the power supply circuit 34 will be described with reference to the flowchart of FIG. The controller 31 turns on the digital transistor DT1 from the output port a before the end of the timer by the electrolytic capacitor C1 (here, immediately after the ignition operation) (S31). As a result, the current flows from the dry battery 32 to the emitter of the transistor Q1 → the base → the digital transistor DT1 → the dry battery 32, and the transistor Q1 is maintained in the on state regardless of the timer. The power supply to 31 is continued. At this time, the electric charge accumulated in the electrolytic capacitor C1 is discharged toward the digital transistor DT1 and disappears.
[0056]
When an electromotive force of a predetermined value or more continues to be generated from the thermocouple 35, it is not necessary to supply power by the dry battery 32.
Therefore, the controller 31 monitors the voltage VCC2 (= 2Vb) at the input port b using the resistors R5 and R6 (S32), and the voltage VCC2 is larger than the voltage (1.8V) of the new dry battery 32. When it is detected that the voltage is 0 V or more, it is assumed that the power from the thermocouple 35 can be used as the power source of the controller 31 instead of the dry battery 32, and a signal for turning off the digital transistor DT1 is transmitted from the output port a ( S33).
Due to the turning-off operation of the digital transistor DT1, electric charge begins to accumulate again in the electrolytic capacitor C1, and when the accumulation is completed, no current flows through the transistor Q1, the transistor Q1 is turned off, and the controller 31 is turned off from the dry battery 32 via the second booster circuit 37. Is turned off. Therefore, thereafter, the electromotive force of the thermocouple 35 is boosted by the second booster circuit 37 and used as the power supply VDD of the controller 31.
[0057]
Here, detection of the voltage Vb at the input port b by the controller 31 will be described.
The electromotive force of the thermocouple 35 before boosting can be detected by turning off the FET1 of the first booster circuit 36 and the digital transistor DT1 of the second booster circuit 37.
The voltage boosted by the first booster circuit can be detected by turning off the digital transistor DT1 of the second booster circuit 37. Even if the digital transistor DT1 is not turned off, if the detected value exceeds the voltage 1.8V of the new dry battery 32, the electromotive force can be detected as a boosted voltage by the first booster circuit 36.
The voltage of the dry battery 32 can be detected by turning on the digital transistor DT1 of the second booster circuit 37.
[0058]
When the controller 31 detects that the voltage VCC2 is equal to or lower than the voltage 1.8V of the new dry battery 32 at the input port b when the power is supplied via the second booster circuit 37 by the electromotive force of the thermocouple 35. (S34: YES), a signal for turning on the digital transistor DT1 is transmitted from the output port a (S35), the power supply circuit 34 is activated, and power is received from the dry battery 32 via the second booster circuit 37. Therefore, even if the electromotive force of the thermocouple 35 suddenly drops due to a gust of wind or the like, power is supplied from the dry battery 32, so that the operation of the controller 31 is not stopped.
[0059]
In addition, when the state where the voltage VCC2 is 1.8 V or less at the input port b continues for 5 minutes (S36: YES), the controller 31 considers that the burner 4 is extinguished, and starts the digital transistor from the output port a. A signal for turning off DT1 is transmitted (S37), the power supply circuit 34 is stopped, and the power supply from the dry battery 32 is stopped. At this time, since no power is supplied from the thermocouple 35, the controller 31 and the motor 38 are stopped.
On the other hand, when power is supplied by the dry battery 32, if the voltage VCC2 exceeds 1.8V in the middle without continuing for 5 minutes (S36: NO), the process returns to step 32 and the voltage is again VCC2 is monitored.
[0060]
Next, the driving timing of the motor 38 will be described.
The controller 31 is provided with two timers that determine the drive timing of the motor 38. One timer detects that the output voltage VCC2 of the first booster circuit 36 is 2.2 V or more for 30 seconds (first condition), and the other timer detects that the ignition switch 33 has been turned on. When it is detected that two minutes have passed (second condition), it is considered that the electromotive force of the thermocouple 35 is stable, and driving of the motor 38 is started using this electromotive force.
[0061]
However, since the load at the start of the motor 38 is very heavy, the motor 38 cannot start rotating only by boosting the electromotive force of the thermocouple 35 as it is.
Therefore, the electric charge generated from the thermocouple 35 is temporarily stored in the electrolytic capacitors C4 and C7, and then the electric power is supplied to the motor 38, whereby the motor 38 can be rotated at a stroke from the stopped state. The applied voltage at this time is about 3.5V. Further, even immediately after the start of the motor 38, the second booster circuit 37 consumes power by the diode D2, so that its output voltage is about 3.2 V, and there is no fear of causing the controller 31 to fail.
[0062]
The drive control of the motor 38 will be described with reference to the flowchart of FIG. Immediately after the ignition operation, the digital transistor DT2 is turned on (S41), the boosted voltage VCC2 from the thermocouple 35 is supplied to the pseudo load 40, and charges are accumulated in the electrolytic capacitors C4 and C7.
[0063]
Then, the two timers in the controller 31 respectively detect that the state where the output voltage VCC2 of the first booster circuit 36 is 2.2 V or more continues for 30 seconds (first condition) (S42: YES), and When it is detected that two minutes have passed since the ignition switch 33 was turned on (second condition) (S43: YES), it is considered that the electromotive force of the thermocouple 35 is stabilized and the electric capacitors C4 and C7 have accumulated electric charges. It is.
[0064]
Then, the digital transistor DT2 is turned off (S44), the energization of the pseudo load 40 is stopped, the FET2 is switched on (S45), and the energization of the motor 38 is started. The power supply voltage of the motor 38 at the time of starting is about 3V.
[0065]
Since the motor 38 which has started to rotate does not require a large amount of electric power thereafter, the motor 38 is maintained at a voltage (2.6 V) obtained by boosting the electromotive force of the thermocouple 35 without accumulating a large amount of charge in the electrolytic capacitors C4 and C7. 38 can continue to be driven.
[0066]
When the output voltage VCC2 of the first booster circuit 36 becomes 2.0V or less during driving of the motor 38 (S46: YES), the necessary voltage cannot be obtained, so the FET 2 is turned off (S47), The drive of the motor 38 is stopped.
If the voltage VCC2 becomes 2.0 V or less during driving of the motor 38, the FET 2 is switched off and the energization of the motor 38 is stopped.
[0067]
As described above, since the electric power is supplied to the motor 38 after being stored by the electrolytic capacitors C4 and C7, the motor 38 can be started even if the thermocouple 38 does not generate a large amount of electric power. Therefore, it is not necessary to use a thermocouple with a large amount of power generation, and the manufacturing cost of the thermocouple can be kept low.
[0068]
In addition, because the second condition of the drive timing of the motor 38 (2 minutes from the start of energization) waits until the electromotive force of the thermocouple 35 is stabilized, the electric capacitors C4 and C7 are surely charged. Can do.
[0069]
Further, a sufficient output voltage can be obtained from the first booster circuit 36 by the first condition of the drive timing of the motor 38 (the state where the output voltage of the first booster circuit 36 is 2.2 V or more continues for 30 seconds). Therefore, it is possible to determine a shortage of electromotive force due to failure of ignition of the burner 4 which cannot be grasped from the second condition, and the motor 38 can be driven after confirming that the thermocouple 35 is actually generating power.
Moreover, in addition to the condition that the output voltage is equal to or higher than a predetermined value, the condition that the state is continued for a predetermined time is also a condition. Therefore, the output voltage of the first booster circuit 36 is temporarily 2.2 V or higher. Even if it becomes, the drive of the motor 38 is not started, but it waits until required electric power is stored. As a result, electric power for driving the motor can be stored more reliably.
[0070]
Even during the motor drive control, the boost efficiency adjustment control is performed simultaneously. While the pseudo load 40 is energized, the boost efficiency adjustment control is performed by adjusting the frequency and duty ratio according to the pseudo load 40. Do.
Even if the output voltage is not maximized by this boosting efficiency adjustment control, if the motor 38 is energized in step 46, the boosting efficiency is adjusted by adjusting the frequency and duty ratio in accordance with the motor 38. Take control.
[0071]
In this way, when energization of the motor 38 is started, the boosting efficiency is adjusted to a certain degree to the motor load, so that the voltage adjusted for the pseudo load 40 is applied to the motor 38 at the time of start-up to ensure driving. Can start.
[0072]
If a pseudo load is not provided, electric power is not consumed by the pseudo load before the motor 38 is energized. Therefore, the frequency and duty ratio that are adjusted to optimize the boosting efficiency are the same as those before the motor 38 is energized. The output voltage of the first booster circuit 36 is also drastically lowered, which is greatly different from the latter. Therefore, immediately after the motor 38 is energized, the voltage applied to the motor 38 is too low and the motor 38 stops.
On the other hand, in the present embodiment, such a problem does not occur because the pseudo load 40 having a load resistance substantially equal to that of the motor 38 is used and the boosting efficiency is adjusted in advance before the motor 38 is started.
[0073]
The generated power can be stably supplied to the motor 38 with an appropriate voltage by repeating the frequency adjustment and the duty ratio adjustment even after the motor 38 is started. Even if the load of the motor 38 fluctuates due to wind entering the motor 38 or the like, the boosting efficiency is adjusted by alternately controlling the frequency and the duty ratio according to the required power.
Such frequency and duty ratio vary depending on component variations, ambient temperature, and load size, but the frequency and duty ratio are repeatedly controlled while feeding back the output voltage (S9 in FIG. 4 and S19 in FIG. 5). By doing so, the output voltage can be accurately controlled.
[0074]
Such a motor 38 generates high frequency noise, and ceramic capacitors C5 and C6 are provided between the first booster circuit 36 and the input port b as a countermeasure against the high frequency noise.
[0075]
The controller 32 is connected with an LED for informing the user of the consumption of the dry battery 32, and before the thermocouple 35 generates power, the voltage of the dry battery 32 is confirmed at the input port b, and the voltage is less than 1.1V. In the case, the LED is turned on.
[0076]
Next, the relationship between the boosting efficiency and the switching element will be described.
The step-up efficiency is greatly affected by the characteristics of the switching element (FET 1) of the first step-up circuit 36. The electric power W that can be taken out from the thermocouple 35 is the open voltage of the thermocouple 35, the internal resistance of the thermocouple 35 is R, and the load of the entire thermocouple circuit connected to the thermocouple 35 (including the motor 38). If the resistance is r and the current flowing through the thermocouple circuit is I,
W = I²Substituting I = V / (R + r) for r,
W = V²r / (R + r)²It becomes. When this equation is differentiated by r to obtain the maximum value, the electric power W that can be taken out from the thermocouple 35 becomes maximum when r = R.
[0077]
For example, when power is generated by combining a plurality of thermocouples, the internal resistance R of the thermocouple 35 is as small as 0.5Ω. Therefore, in order to boost the power from here and extract a large power, r = R (that is, r = 0.5Ω), and it is necessary to keep the impedance of the booster circuit small.
For this purpose, it is necessary to lower the on-resistance of the element that performs switching (power MOSFET, that is, FET1), and it is necessary to increase the gate voltage (input voltage) of FET1 to some extent.
[0078]
If the output power VCC2 boosted by the first booster circuit 36 is used as the power supply for the controller 31, the voltage changes due to load fluctuations. Therefore, once the boosted voltage is lowered, the ON characteristic of the switching element is It worsens and falls into a vicious circle in which the boosting efficiency is lowered and the boosted voltage is lowered.
Therefore, in the present embodiment, a switching element that has a large effect on the boosting efficiency is connected to a booster circuit (second booster circuit 37) different from the booster circuit (first booster circuit 36) of the main load (motor 38). A boosted power supply is used to stabilize the voltage.
[0079]
In the thermoelectric generator control apparatus 30 described above, since the first booster circuit 36 boosts the electromotive force of the thermocouple 35, the motor 38 can be started up without generating a high electromotive force by connecting a large number of thermocouples. The manufacturing cost of the pair is low.
[0080]
Next, the boosting efficiency will be described. The voltage required for the winding 38a of the motor 38 is 2.6V and does not need to be the same voltage (3V) as the controller 31 and the IC 38b.
For example, when it is desired to boost from 1V to 3V, when trying to boost from 1V to 3V at once, the boosting difference may be too large to be sufficiently boosted to 3V. On the other hand, the first booster circuit 36 first boosts the voltage from 1V to 2.6V with a margin, and then the second booster circuit 27 reliably boosts 2.6V to 3V.
Thus, by boosting in two stages, it is possible to boost to a desired voltage without difficulty.
In addition, since the boosting efficiency decreases due to an increase in energy loss as the boosting difference increases, the booster circuit (second booster circuit 37) for the applied voltage VDD (3V) of the IC 38b and the applied voltage VCC2 (2. By separating the 6V) boosting circuit (first boosting circuit 36), the boosting efficiency in the winding 38a becomes better than when the boosting target value is 3V.
As a result, the generated power can be used effectively.
[0081]
Further, in the thermoelectric generator control device 30, since the power supply source to the controller 31 is switched from the dry battery 32 to the thermocouple 35, the dry battery 32 can be used for a long time without wasting the dry battery 32. . For this reason, it is not necessary to perform dry battery replacement frequently.
[0082]
Although the embodiment of the present invention has been described above, the present invention is not limited to such an embodiment, and it is needless to say that the present invention can be implemented in various modes without departing from the gist of the present invention.
For example, in the adjustment control of the boost efficiency, the frequency and the duty ratio may be adjusted once instead of adjusting the frequency and the duty ratio alternately and repeatedly.
Further, in order to increase the voltage applied to the motor at the time of startup, the load resistance of the pseudo load 40 may be made relatively small, for example, about half of the load resistance of the motor 38.
In addition, the driving timing of the motor 38 is set to the first condition “the state where the output voltage of the first booster circuit 36 is 2.2 V or higher for 30 seconds” and the second condition “two minutes have elapsed since the ignition switch 33 was turned on. Instead of setting the time when both of the two conditions are satisfied, the first condition may be satisfied, or the second condition may be satisfied.
[0083]
Further, instead of waiting for a predetermined time (for example, 30 seconds) as in the first condition of the driving timing of the motor 38 (S42), as shown in FIG. 8, the output voltage of the first booster circuit 36 is predetermined. The condition may be that the voltage (eg, 2.2 V) or higher (S142).
In addition, the timing start condition of the second condition of the driving timing of the motor 38 may be not the time of the ignition operation but the time of the start of the operation of the first booster circuit 36. That's fine.
[0084]
The timing for switching the power supply source to the controller 31 from the power of the dry battery 32 to the generated power of the thermocouple 35 is not set when the output voltage of the first booster circuit 36 reaches a predetermined voltage or higher, but in this state. May be continued for a predetermined time. For example, as shown in FIG. 9, when VCC2 is determined to be 2V or more in S32 of FIG. 6, when the state continues for 10 seconds as in S132, power from the dry battery to the thermocouple is transferred to the controller 31. The supply source may be switched.
In this case, from the dry battery 32 until the required operating power can be supplied from the thermocouple 35 to the controller 31 via the first booster circuit 36 without being affected by the temporary increase in the electromotive force of the thermocouple 35. Since power is supplied, the operation of the controller 31 can be continued more reliably.
[0085]
【The invention's effect】
  As described above in detail, according to the thermoelectric generator control device of the first aspect of the present invention, the boosting efficiency of the electromotive force of the thermoelectric generator is adjusted and the generated electric power is supplied to the load. Can be driven.
  In addition, since the boosting efficiency is adjusted, the generated power can be used effectively.
  Furthermore, the power for the boosting efficiency control circuit is divided from the power for the power supply of the load and boosted by the second boosting circuit, so that the operation of the boosting efficiency control circuit is stable, the boosting efficiency can be adjusted appropriately, and power is generated. Electricity can be used effectively.
  Even if the required power fluctuates with the load, a stable voltage different from the load is applied to the boosting efficiency control circuit, so that the load can be stably driven with high boosting efficiency.
[0086]
  Furthermore, according to the thermoelectric generation control device of claim 2 of the present invention,Since the boost efficiency is temporarily adjusted according to the required power of the pseudo load before the motor is driven, the boost efficiency does not change drastically when the motor is driven, and the motor does not operate due to a sudden drop in the output voltage to the motor. Can be prevented.
[0087]
  Furthermore, according to the thermoelectric generation control device of claim 3 of the present invention,Since the boosted efficiency of the electromotive force of the thermoelectric generator is adjusted and the generated power is supplied to the load, the load can be driven stably.
In addition, since the boosting efficiency is adjusted, the generated power can be used effectively.
Furthermore, since the boosting efficiency is temporarily adjusted in advance according to the required power of the pseudo load before the motor is driven, the boosting efficiency does not change drastically when the motor is driven, and the motor is not affected by a sudden drop in the output voltage to the motor. Operation can be prevented.
[Brief description of the drawings]
FIG. 1 is a thermoelectric generation control circuit diagram according to the present embodiment.
FIG. 2 is a schematic cross-sectional view of a fan-equipped infrared heater as the present embodiment.
FIG. 3 is a flowchart showing boosting efficiency adjustment control in the first booster circuit according to the present embodiment;
FIG. 4 is a flowchart illustrating frequency adjustment control according to the present embodiment.
FIG. 5 is a flowchart showing duty ratio adjustment control according to the present embodiment;
FIG. 6 is a flowchart showing control of a power supply circuit according to the present embodiment.
FIG. 7 is a flowchart showing motor drive control as the embodiment.
FIG. 8 is a flowchart showing motor drive control as a modified example.
FIG. 9 is a flowchart showing control of a power supply circuit as a modified example.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Stove, 4 ... Burner, 9 ... Fan, 30 ... Thermoelectric power generation control device, 31 ... Controller, 32 ... Dry cell, 33 ... Ignition switch, 34 ... Power supply circuit, 35 ... Thermocouple, 36 ... First boost circuit, 37 ... second booster circuit, 37a ... IC, 38 ... motor, 38a ... winding, 38b ... IC, 40 ... pseudo load, FET1 ... switching element, L2 ... coil, C1 to C4, C7 ... electrolytic capacitor, b ... input port , D: power port.

Claims (3)

A thermoelectric generator that generates electricity by heat;
A booster circuit for inducing a voltage in the coil by turning on and off the switching element to boost the electromotive force input from the thermoelectric generator;
A load energizing circuit for energizing the load using the boosted power as a power source;
Voltage detection means for detecting the power supply voltage of the load;
A step-up efficiency control circuit for adjusting the step-up efficiency by controlling the switching element so that the output voltage of the step-up circuit, which is the detection voltage of the voltage detection means, is maximized ;
A second booster circuit for further boosting the output voltage boosted by the booster circuit;
And the electric power boosted by the second booster circuit is used as a power source of the boosting efficiency control circuit . The load is a motor,
A pseudo load that consumes the boosted electromotive force instead of the motor is provided, and before the motor is driven, the pseudo load is energized so that the power supply voltage of the pseudo load is maximized. 2. The thermoelectric generator control device according to claim 1, wherein temporary adjustment is performed . A thermoelectric generator that generates electricity by heat;
A booster circuit for inducing a voltage in the coil by turning on and off the switching element to boost the electromotive force input from the thermoelectric generator;
A load energizing circuit for energizing the motor using the boosted power as a power source;
Voltage detection means for detecting the power supply voltage of the motor;
A step-up efficiency control circuit for adjusting the step-up efficiency by controlling the switching element so that the output voltage of the step-up circuit, which is the detection voltage of the voltage detection means, is maximized;
A pseudo load that consumes electric power obtained by boosting the electromotive force instead of the motor;
And, before driving the motor, the boosting efficiency is temporarily adjusted so that the pseudo load is energized to maximize the power supply voltage of the pseudo load .

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