JP7312088B2 - Power conversion device and power conversion control device - Google Patents

Description

The present invention relates to a power conversion device that converts power supplied from a power source, and a power conversion control device that constitutes the power conversion device.

Some power converters include a converter that can step up and down an applied voltage by turning on and off a switch element. Some power converters equipped with such converters detect the voltage of a power system that supplies power, set a target voltage value, and switch elements so as to cause the converter to generate power at the set target voltage value. There is an on-off drive (see, for example, Patent Document 1).

There are various types of power sources that generate power to be converted, that is, to be stepped up or stepped down in voltage by a converter. The solar cell described in Patent Document 1 is one type of power supply. Most of the power sources that generate power through power generation, including solar cells, have their power generation amount fluctuate to a relatively large extent depending on the environment.

Japanese Patent No. 5349688

For power with relatively large fluctuations in the amount of power generated, it is necessary to appropriately control the voltage or current. As control for that purpose, for example, maximum power point tracking control (MPPT: Maximum Power Point Tracking) is known. By employing this MPPT, the power generated by the power supply can always be maximized.

In addition to solar cells, for example, thermoelectric conversion modules are known as power sources whose power generation amount fluctuates relatively greatly. In this thermoelectric conversion module, the open-circuit voltage increases linearly as the temperature difference increases. It is known that the voltage at which the thermoelectric power generation module reaches the maximum power point is half the open voltage. Power is proportional to the square of voltage.

When a power supply whose power generation amount fluctuates relatively greatly is employed, it is desirable that the power conversion device has a rating that can withstand the maximum power generation amount. This is because the power converter can always supply converted power while the power supply is generating power. However, the higher the rating, the larger, heavier, and more expensive the power converter. Therefore, it is not always appropriate to assume the maximum amount of power generation and prepare a power converter. Because of this, it is also important to support a wider range of power generation amounts within the rated range, in other words, within the range in which operation is guaranteed.

The present invention has been made to solve this problem. When power exceeding the rating is input, the current of the power is increased from the current at the maximum power point to suppress the power within the rating. The object of the present invention is to provide a power conversion device and a power conversion control device that can continue to operate.

The power conversion device according to the present invention includes a first switch element capable of supplying and interrupting power supply from a thermoelectric conversion module that converts heat into electric power, and a first switch element capable of short-circuiting between both ends of the thermoelectric conversion module. A converter that includes two switch elements, and boosts and steps down power by turning on and off the first switch element and the second switch element, and a voltage detector that detects the voltage of the power supplied to the converter and outputs a voltage value. a first set output voltage value, a set upper limit voltage value set based on the rating of the converter, and a second setting set between the set upper limit voltage value and the first set output voltage value a target setting unit for setting an output voltage value; and when the voltage value detected by the voltage detector is larger than the second set output voltage value , power is supplied by the first switch element and the second switch element is activated. and an output voltage control unit that performs control for stepping down the voltage of the power by on/off driving.

A power conversion control device according to the present invention includes a first switch element capable of supplying and interrupting power supply from a thermoelectric conversion module that converts heat into power, and short-circuiting between both ends of the thermoelectric conversion module. A voltage detector that detects the voltage of power supplied to a converter that includes a second switch element and that steps up and down the voltage of the power by on/off driving of the first switch element and the second switch element and outputs a voltage value. a target setting unit in which a plurality of setting values used for controlling the output voltage generated by the converter based on the result of comparison between the voltage value detected by the voltage detector and the voltage detector are set; Power is supplied by turning on the first switch element based on a comparison result between each of the plurality of set values and the voltage value detected by the voltage detector , and the second switch element is turned on and off. and an output voltage control unit that performs control for stepping down the voltage of the electric power.

According to the present invention, when power exceeding the rating is input, the current of the power is increased from the current at the maximum power point, and the power can be suppressed within the rating to continue operation.

BRIEF DESCRIPTION OF THE DRAWINGS It is a figure which shows the structural example of the power converter device which concerns on Embodiment 1 of this invention. FIG. 10 is a diagram for explaining an example of power generation characteristics that change depending on the temperature difference of one thermoelectric conversion module; FIG. 4 is a diagram for explaining an example of power generation characteristics that change with a temperature difference in a thermoelectric conversion module group in which a plurality of thermoelectric conversion modules are connected in series; It is a figure explaining each mode provided in order to turn on/off drive each switch element, and the example of the content. It is a figure explaining the example of the range in which each mode is set. FIG. 10 is a diagram for explaining examples of various states of the converter when mode 3 is set, and examples of the details of driving each switch element; FIG. 10 is a diagram for explaining examples of various states of the converter when mode 4 is set, and examples of the details of driving each switch element; 7A and 7B are diagrams for explaining examples of various states of the converter when mode 6 is set and examples of the details of driving each switch element; FIG. 8A and 8B are diagrams for explaining examples of various states of the converter when modes 7 and 8 are set, and examples of the details of driving each switch element; FIG. It is a figure explaining the example of control of the output electric power according to a temperature difference. It is a figure explaining the control example of the input voltage according to a temperature difference. It is a figure explaining the control example of the output current according to a temperature difference.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of a power conversion device and a power conversion control device according to the present invention will be described with reference to the drawings.

Embodiment 1.
FIG. 1 is a diagram showing a configuration example of a power converter according to Embodiment 1 of the present invention. This power conversion device 10 converts power supplied from a power source corresponding to a power source whose amount of power to be supplied fluctuates. In FIG. 1, a thermoelectric conversion module group TMG in which a total of n thermoelectric conversion modules TMG1 to TMGn are connected in series is connected to the power converter 10 as the power source. Any one thermoelectric conversion module is denoted by "TMGz" as a code.

FIG. 2 is a diagram for explaining an example of power generation characteristics that vary depending on the temperature difference of one thermoelectric conversion module, and FIG. It is a figure explaining the example of a characteristic. In both FIGS. 2 and 3, the horizontal axis represents voltage, the left vertical axis represents current, and the right vertical axis represents power. Before describing FIG. 1, the power generation characteristics of the thermoelectric power generation module TMGz and the thermoelectric power generation module group TMG, which change depending on the temperature difference, will be specifically described.

In FIG. 2, 201 indicates the voltage-power characteristics of the thermoelectric conversion module TMGz when the temperature difference is 90 degrees. Similarly, 202 and 203 indicate voltage-power characteristics when the temperature difference is 80 degrees and 70 degrees, respectively. Reference numeral 205 denotes voltage-current characteristics of the thermoelectric conversion module TMGz when the temperature difference is 90 degrees. Similarly, 206 and 207 indicate voltage-current characteristics when the temperature difference is 80 degrees and 70 degrees, respectively.

In FIG. 3, 211 indicates the voltage-power characteristics of the thermoelectric conversion module group TMG when the temperature difference is 90 degrees. Similarly, 212 and 213 indicate voltage-power characteristics when the temperature difference is 80 degrees and 70 degrees, respectively. 215 shows the voltage-current characteristics of the thermoelectric conversion module group TMG when the temperature difference is 90 degrees. Similarly, 216 and 217 indicate voltage-current characteristics when the temperature difference is 80 degrees and 70 degrees, respectively.

The amount of power generated by the thermoelectric conversion module TMGz and the thermoelectric conversion module group TMG is proportional to the square of the temperature difference between the high temperature side and the low temperature side, and the open-circuit voltage varies in proportion to the temperature difference. The amount of change in the power generation amount according to the temperature difference is relatively large, as shown in FIGS. The temperature difference may change greatly depending on changes in the installation environment, the state of the heat source that causes the temperature difference, and the like. Therefore, in order to simply cope with the maximum conceivable temperature difference, it is necessary to prepare a power conversion device with a high rating corresponding to the temperature difference, which increases the cost of the power conversion device. More specifically, the power converter becomes larger, heavier, and more expensive. Also, the open electromotive force is twice the voltage at the maximum load point. For this reason, the power converter is required to have a relatively high rated voltage.

In the first embodiment, in response to changes in the input voltage exceeding the rated voltage of the power conversion device 10, in order to suppress the voltage of the supplied power so as not to exceed the rated voltage, the amount of input current is controlled and a wider range of Correspond to the amount of input power. In other words, focusing on the voltage value or current value of the supplied power, the supplied power is manipulated, and the power obtained by the manipulation is converted and supplied to the outside. With such measures, a lower-cost power conversion device 10 can be used. For this reason, the range of the input electric energy that can be handled becomes wider with respect to the cost of the power converter 10 . In addition, even if the thermoelectric conversion module group TMG, which is a power source, generates more power than the rated power, the power can be suppressed within the rated power and the converted power can be supplied to the outside.

In Embodiment 1, the thermoelectric conversion module group TMG is connected to the power converter 10 as a power supply, but the power supply connected to the power converter 10 is not limited to the thermoelectric conversion module group TMG. This is because the thermoelectric conversion module group TMG and the thermoelectric conversion modules TMGz constituting it are not the only power sources whose supplied power fluctuates. For example, the amount of power generated by the solar cell described in Patent Document 1 also fluctuates relatively greatly depending on the environment.

Returning to the description of FIG. The power converter 10 includes a converter 1, an inverter 2, a microcomputer 3, a gate pulse generator 4, two voltage sensors 5 and 6, and two current sensors 7 and 8, as shown in FIG. The microcomputer 3 corresponds to the control unit in the first embodiment, and functions as the power conversion control device according to the first embodiment. The microcomputer 3 will hereinafter be abbreviated as "microcomputer 3".

The converter 1 is a converter capable of stepping up and down voltage, and includes two smoothing capacitors Cin and Cout, two switch elements Q1 and Q2, two diodes D1 and D2, and an inductor L, as shown in FIG. . In Embodiment 1, the switching element Q1 corresponds to the first switching element, and the switching element Q2 corresponds to the second switching element. The two switch elements Q1 and Q2 are both IGBTs (Insulated Gate Bipolar Transistors).

The smoothing capacitor Cin is connected across the thermoelectric conversion module group TMG. Thereby, the voltage generated by the thermoelectric conversion module group TMG is applied to the smoothing capacitor Cin, and the voltage applied from the thermoelectric conversion module group TMG to the converter 1 is smoothed.

The collector of the switch element Q1 is connected to the positive terminal of the smoothing capacitor Cin. The emitter of switch element Q1 is connected to the cathode of diode D1 and inductor L. Therefore, by turning on/off the switch element Q1, it is possible to supply and cut off the electric power generated by the group of thermoelectric power generation modules TMG. The switch element Q1 is turned on and off mainly to step down the voltage of the supplied power.

Each gate of the two switch elements Q1 and Q2 is connected to the gate pulse generator 4. FIG. Therefore, the two switch elements Q1 and Q2 are turned on and off by pulses generated by the gate pulse generator 4. FIG. "Q1_gate" and "Q1_gate" shown in FIG. 1 represent on/off driving pulse signals supplied to the gates of the switch elements Q1 and Q2, respectively. In the first embodiment, the pulse signal is generated by the gate pulse generator 4 by PWM (Pulse Width Modulation) control. The two switch elements Q1 and Q2 may be other power devices such as MOSFETs (Metal Oxide Semiconductor Field Effect Transistors).

The other end of inductor L is connected to the collector of switch element Q2 and the anode of diode D2. The emitter of the switch element Q2 is connected to the negative terminals of the two smoothing capacitors Cin and Cout, the anode of the diode D1, and the negative side of the thermoelectric conversion module group TMG. Therefore, it is possible to short-circuit both ends of the thermoelectric conversion module group TMG during the ON-driving period of the switch element Q1 and cancel the short-circuit by turning the switch element Q2 on and off. The switch element Q2 is turned on and off mainly to boost the voltage of the supplied power.

One terminal of the smoothing capacitor Cout is connected to the cathode of the diode D2, and the other terminal is connected to the emitter of the switch element Q2. Thereby, the smoothing capacitor Cout smoothes the voltage of the power supplied from the converter 1 as an output.

A voltage sensor 5 is connected to both ends of the smoothing capacitor Cin, that is, to both ends of the thermoelectric conversion module group TMG. Therefore, the voltage sensor 5 outputs a signal indicating the voltage value across the smoothing capacitor Cin as a voltage detection result. Here, the voltage value is expressed as "input voltage value Vin". For convenience, the input voltage value Vin is also used to mean information output by the voltage sensor 5 . Similarly, the voltage value indicated by the signal output by the voltage sensor 6 is the "output voltage value Vout", the current value indicated by the signal output by the current sensor 7 is the "input current value IL", and the signal output by the current sensor 8 is indicated. A current value is described as "output current value Iout". Voltage sensor 5 corresponds to the first voltage detector in the first embodiment.

A voltage sensor 6 is also connected across the smoothing capacitor Cout. Therefore, the voltage sensor 6 outputs a signal indicating the voltage value across the smoothing capacitor Cout. Here, the voltage value is expressed as "output voltage value Vout". Voltage sensor 6 corresponds to the second voltage detector in the first embodiment.

Current sensor 7 detects a current flowing through inductor L and outputs a signal indicating the value of the detected current. Here, the current value is expressed as "input current value IL". Current sensor 8 detects the current flowing through diode D2 and outputs a signal indicating the value of the detected current. Here, the current value is expressed as "output current value Iout". The current sensors 7 and 8 respectively correspond to the first current detector and the second current detector in the first embodiment.

The converter 1 configured as described above is a conversion circuit that performs direct current (DC)-direct current conversion. The inverter 2 is a conversion circuit that performs DC-AC conversion. The inverter 2 includes a smoothing capacitor CD and an inverter body 21, as shown in FIG.

Smoothing capacitor CD smoothes the voltage applied from converter 1 . The inverter body 21 is connected across the smoothing capacitor CD. This inverter body 21 has, for example, three half bridges or full bridges. The power converted into alternating current by the inverter main body 21 is supplied to the load. A circuit configuration of the inverter main body 21 is not particularly limited.

In Embodiment 1, the power conversion device 10 includes two conversion circuits, the converter 1 and the inverter 2, as described above. However, as a conversion circuit, at least the converter 1, that is, a conversion circuit capable of stepping up and down the voltage should be provided. The conversion circuit is configured to include one or more switch elements of two types with different uses so that voltage can be stepped up and down.

As shown in FIG. 1, the microcomputer 3 has a maximum load resistance setting section 31, an input power calculation section 32, a control state determination section 33, a converter state determination section 34, an output voltage control section 35, and a target setting section 36. Realized. Thereby, the microcomputer 3 functions as a power conversion control device according to the first embodiment.

The maximum load resistance setting unit 31 sets the combined value Ro of the internal resistances of the thermoelectric conversion module group TMG. The synthetic value Ro may be set by setting a value input as data from the outside as the synthetic value Ro. Alternatively, both switch elements Q1 and Q2 may be turned on, and a value calculated using the input voltage value Vin and the input current value IL obtained in that state may be used as the combined value Ro. In this case, the composite value Ro can be calculated by Ro=Vin/IL-(Rq1+Rq2). Rq1 and Rq2 are on-resistance values of the switch elements Q1 and Q2. Since these on-resistance values Rq1 and Rq2 are sufficiently small compared to the combined value Ro, they may be ignored.

The input power calculation unit 32 calculates the input power value Pin using the combined value Ro set by the maximum load resistance setting unit 31 and the input voltage value Vin. The input power value Pin can be calculated by Pin=Vin ² /Ro, for example. The input power calculation section 32 and the maximum load resistance setting section 31 correspond to the input power calculation section in the first embodiment.

In Embodiment 1, a plurality of setting values are provided for controlling converter 1 in consideration of the rating of converter 1 . The target setting unit 36 is a component for realizing control reflecting a plurality of provided set values. The target setting unit 36 outputs data indicating various set values to the control state determination unit 33 , the converter state determination unit 34 and the output voltage control unit 35 .

In FIG. 1, "Vco", "Vch", "VH", "IH", "Pco1", "Pco2", and "PH" are shown as setting values set by the target setting unit 36. FIG. These setting values are as follows.

Vco and Vch are set values used to control the voltage generated by the converter 1 . Vch is a value greater than Vco, and indicates a voltage value at which suppression control of the generated voltage is started. Hereinafter, Vco will be referred to as "first set voltage value Vco", and Vch will be referred to as "second set voltage value Vch". Both the first set voltage value Vco and the second set voltage value Vch correspond to the set output voltage value in the first embodiment. More specifically, the first set voltage value Vco corresponds to the first set output voltage value, and the second set voltage value Vch corresponds to the second set output voltage value.

VH is also a voltage value set in consideration of the rating of the converter 1, for example, and serves as a reference for starting control to protect the converter 1. FIG. Thereby, the conversion of the electric power supplied from the thermoelectric conversion module group TMG is performed on the condition that the voltage value of the electric power is VH or lower. If the voltage value exceeds VH, the converter 1 is prevented from converting power. That is, converter 1 is stopped. For this reason, the magnitude relationship between them, including the first set voltage value Vco and the second set voltage value Vch, is Vco<Vch<VH. Hereinafter, VH will be referred to as "set upper limit voltage value VH".

As described above, the converter 1 is a conversion circuit that steps up and down the voltage of the power supplied from the thermoelectric conversion module group TMG. Therefore, each of the set voltage values Vco and Vch serves as a target value for the voltage to be generated by the converter 1, and also serves as a basis for determining whether to step up or step down the voltage of the power to be supplied. It also becomes a standard. The set upper limit voltage value VH is used to determine whether or not to cut off the supplied power because the power conversion device 10 may be damaged by the supplied power.

Power converter 10 is damaged even if excessive current is supplied. IH is a current value set so as not to damage the power conversion device 10 due to excessive current supply. Therefore, IH is also used for determining whether or not to cut off the power supply, like the set upper limit voltage value VH. Hereinafter, IH will be referred to as "set upper limit current value IH".

Power can be determined by multiplying voltage and current. Power depends on both voltage and current. Therefore, in the first embodiment, input power value Pin is used to select the control method of converter 1, in other words, to switch the control method. Pco1, Pco2, and PH are all threshold power values for selecting a control method, and are set in consideration of ratings, for example.

Pco1 is a threshold value set for switching the control method based on the amount of power supplied to converter 1 . Pco2 is a threshold set as an upper limit of the amount of electric power to be output from the converter 1, and is a rated value, for example. PH is a threshold set to protect the converter 1 from supplying an excessive amount of power. The magnitude relation between them is Pco2<Pco1<PH. The reason why Pco2<Pco1 is established is that the loss in the converter 1 and the like are taken into consideration. Hereinafter, Pco1 will be referred to as "set input power value Pco1", Pco2 will be referred to as "set output power value Pco2", and PH will be referred to as "input upper limit power value PH".

The value of the power supplied from the converter 1 can be calculated, for example, by multiplying the output voltage value Vout by the output current value Iout. The set output power value Pco2 is compared with the value thus obtained. Henceforth, the value is described as "output electric power value Pout."

In Embodiment 1, the converter 1 is controlled such that the output power value Pout is suppressed to the set output power value Pco2 or less. Therefore, the input power value Pin is compared with the set input power value Pco1 and the input upper limit power value PH, respectively, and the control contents are switched according to the comparison results. When power is supplied, basically, the output power value Pout is maximized while giving priority to the output voltage value Vout becoming the first set voltage Vco, so that the output power value Pout is equal to the set output power value Pco2. control so that When the input power value Pin is equal to or higher than the set upper limit power value PH, both switch elements Q1 and Q2 are turned off. The converter 1 is thereby stopped and protected from the supplied power.

In the first embodiment, when the input power value Pin is equal to or greater than the set input power value Pco1, the input power value Pin is increased to the set input power value Pco1 by increasing the current flowing through the thermoelectric conversion module group TMG. Suppress the following. An increase in the current flowing through the thermoelectric conversion module group TMG can be realized by lengthening the short-circuit period during which both the first and second switch elements Q1 and Q2 are turned on. As a result, the operation can be continued while maintaining the output voltage value Vout at the first set voltage value Vco and the output power value Pout at the set output power value Pco2. According to the characteristics of each thermoelectric conversion module TMGz constituting the thermoelectric conversion module group TMG, the voltage value can be suppressed by increasing the current value. Hereinafter, the value of the current supplied from the thermoelectric conversion module group TMG will be referred to as "input current value Iin" to distinguish it from the input current value IL.

As described above, in the first embodiment, the input power value Pin is compared with the set input power value Pco1 and the upper limit input power value PH, and the control method for driving the switch elements Q1 and Q2 is changed depending on the situation. to control the output voltage value Vout and the output current value Iout. When the input power value Pin is equal to or greater than the set input power value Pco1, the input current value Iin is increased and the input power value Pin is suppressed. The reason why the current is increased in order to suppress the input power value Pin in this way is that when the input voltage is increased, it is necessary to employ components with a higher withstand voltage. The higher the voltage resistance of the component, the larger the size. Therefore, by suppressing the withstand voltage required for the parts, the converter 1 and furthermore the power conversion device 10 can be made smaller.

By dynamically changing the control method as described above, the converter 1 maintains a constant output voltage value Vco and output power even if the input power value Pin becomes equal to or greater than the set input power value Pco1 within the rated range. It is possible to supply power with a value Pco2. Hereinafter, the control that increases the input current value Iin and suppresses the input power value Pin will be referred to as "input power suppression control", and the control that emphasizes obtaining the set output power value Pco2 will be referred to as "maximum power control". Control for stopping the converter 1 for protection is written as "protection stop control".

As the current flowing through the thermoelectric conversion module TMGz increases, the amount of heat generated increases due to its own electrical resistance. This internal heat generation and the Peltier effect caused by energization work to reduce the temperature difference in the thermoelectric conversion module TMGz. As a result, the amount of power generated by the thermoelectric conversion module TMGz is suppressed. As the input current value Iin increases, the current flowing through the thermoelectric conversion module TMGz also increases. When the thermoelectric conversion module TMGz is used as the power source, the electric power generated by the thermoelectric conversion module TMGz is increased by setting the current value at the input power value Pin to be larger than 1/2 of the short-circuit current value at the maximum power point. It has the advantage of being suppressed. Due to this advantage, even if the thermoelectric conversion module group TMG generates power exceeding the rated power, the power can be suppressed within the rated power by controlling the current. As a result, the increase in size of the power conversion device 10 and the manufacturing cost can be further suppressed. The value of the short-circuit current at the maximum power point is hereinafter referred to as "short-circuit current value Is".

Control state determination unit 33 compares input power value Pin input from input power calculation unit 32 with set input power value Pco1 and set upper limit power value VH, and determines a desirable control method for the current state of converter 1 . Based on this determination, one of activation control, input power suppression control, maximum power control, and protection stop control is selected. The determination result is output to converter state determination unit 34 . In addition to the determination result, the converter state determination unit 34 stores an input voltage value Vin, an output voltage value Vout, an output current value Iout, a first set voltage value Vco, a second set voltage value Vch, a set upper limit voltage value VH, The set output power values Pco1 and Pco2 and the input upper limit power value PH are input. The control state determination unit 33 corresponds to the determination unit in the first embodiment.

In the first embodiment, a plurality of modes are provided for ON/OFF driving of the switch elements Q1 and Q2. Converter state determination unit 34 receives determination results from control state determination unit 33, input voltage value Vin, input current value IL, output voltage value Vout, output current value Iout, first set voltage value Vco, second set voltage value Vch. , the set upper limit voltage value VH, the set input power value Pco1, and the input upper limit power value PH are used to select the ON/OFF drive mode of the switch elements Q1 and Q2. This selection result is notified to the output voltage control unit 35 . The output voltage control unit 35 also has an input voltage value Vin, an input current value IL, an output voltage value Vout, a first set voltage value Vco, a second set voltage value Vch, a set upper limit voltage value VH, and a set upper limit current value. IH, set output power values Pco1 and Pco2, and input upper limit power value PH are input.

The output voltage control unit 35 drives the switch elements Q1 and Q2 in the mode selected by the converter state determination unit 34. FIG. When the control state determination unit 33 or the converter state determination unit 34 selects protection stop control, the output voltage control unit 35 turns off both switch elements Q1 and Q2. When protection stop control is not selected, the output voltage control unit 35 turns on or turns on/off at least one of the switch elements Q1 and Q2. When turning on/off at least one of the switch elements Q1 and Q2, the output voltage control unit 35 controls the input voltage value Vin, the input current value IL, the output voltage value Vout, the first set voltage value Vco, and the second set voltage value. The ON period is determined with reference to Vch, the set upper limit voltage value VH, the set upper limit current value IH, and the set output power value Pco2. The OFF period is automatically determined by the ON period. The gate pulse generator 4 is driven by the output voltage control section 35 according to this determination, and generates signals to be output to the gates of the switch elements Q1 and Q2. In Embodiment 1, the cycle, which is the unit of PWM control, is constant.

The details of driving the switch elements Q1 and Q2 change depending on the mode. The switch element Q1 is turned on when protection stop control is not selected, or is turned on and off. The switch element Q2 is turned on, off, or on/off driven when the protection stop control is not selected. For this reason, both the switch elements Q1 and Q2 are turned on and off during the whole non-selection of the protection stop control. The output voltage control unit 35 determines the ON period of the switch element that is turned on and off among the switch elements Q1 and Q2, that is, each duty ratio. For this reason, the output voltage control section 35, the converter state determination section 34, and the control state determination section 33 correspond to the control section in the first embodiment.

FIG. 4 is a diagram for explaining each mode provided for on/off driving each switch element and an example of the contents thereof. FIG. 5 is a diagram explaining an example of the range in which each mode is set. In FIG. 5, the horizontal axis represents the input voltage value Vin, that is, the voltage generated by the thermoelectric conversion module group TMG, and the vertical axis represents the input power value Pin, that is, the amount of power supplied from the thermoelectric conversion module group TMG. Accordingly, FIG. 5 shows the range of each mode selected by the input voltage value Vin and the input power value Pin. In FIG. 5, the vertical axis also shows the ratio when the set input power value Pco1 is 1. In FIG.

“450 W” shown in FIG. 5 is a specific example of the set input power value Pco1. Also, "350V" "450V" "540V". These are specific examples of the first set voltage value Vco, the second set voltage value Vch, and the set upper limit voltage value VH, respectively. In such a case, specific examples of the set output power value Pco2 and the upper limit input power value PH are, for example, "440 W" and "540 W".

As shown in FIG. 4, in the first embodiment, modes 1 to 9 are provided as modes for on/off driving the switch elements Q1 and Q2. Each mode is divided into lines to indicate the conditions under which the mode is selected for each mode. In each column, different types of conditional content, control content, etc. are written.

In FIG. 4, "Q1" and "Q2" are written in two columns obtained by dividing the "switch element" column. "Q1" and "Q2" represent switch elements Q1 and Q2, respectively. "ON", "OFF", and "SW" written in the column of the columns of "Q1" and "Q2" indicate the driving contents of the corresponding switch elements, respectively. Specifically, "ON", "OFF", and "SW" respectively represent always ON within one cycle of PWM control, always OFF during one cycle, and ON/OFF drive within one cycle. Also, "current control" and "voltage control" written together with "SW" in this column are on/off drive for current control for input power suppression control and voltage control for maximum power control, respectively. It is shown that.

The operating state means the operating state of converter 1 . "Startup (high voltage)", "startup (low voltage)", "first boost", "bypass", etc. all represent one of the operating states. “Startup (high voltage)” and “startup (low voltage)” indicate that the contents of control are changed according to the input voltage value Vin at the time of startup. "START", "Bst", "BYP", etc. are symbols corresponding to operation states written in Japanese.

"Control state determination unit" is also written in the column of "Pin". This column shows the control method determined by the control state determination unit 33 according to the input power value Pin.

The row in the column labeled "Vin" is also labeled "converter state determination unit". This column shows the comparison results of the converter state determining unit 34 using the first set voltage value Vco, the second set voltage value Vch, and the set upper limit voltage value VH with respect to the input voltage value Vin. Converter state determination section 34 selects a mode based on the comparison result and the control method determined by control state determination section 33 .

As noted above, the final mode is typically determined by converter state determination section 34 . Even if the input power value Pin is less than the input upper limit power value PH and the input voltage value Vin is equal to or less than the set upper limit voltage value VH, if the input current value IL exceeds the set upper limit current value IH, the converter state Mode 9 is set by the determination unit 34 . When the input power value Pin is equal to or greater than the input upper limit power value PH, the control state determination unit 33 selects protection stop control. The selection establishes mode 9 regardless of the value of the input voltage value Vin.

The column in which "Vout" is written is also written with "output voltage control unit". The output voltage value Vout is controlled by the output voltage control section 35 . For this reason, this column shows voltage values that the output voltage control unit 35 targets as the output voltage value Vout. "Vout=0" written in that column basically represents the voltage value that the output voltage control unit 35 targets as the output voltage value Vout. "Vout≈Vin<Vch" indicates that the output voltage value Vout fluctuates according to the input voltage value Vin within a range where the output voltage value Vout is less than the second set voltage value Vch. The output voltage value Vout is substantially equal to the input voltage value Vin. Therefore, the target value of the output voltage value Vout does not exist here, but only the upper limit exists.

Output power value Pout is a value obtained as a control result of converter 1 . Columns labeled "Pout" and "control result" show the range of the output power value Pout and the variation of the input current value IL for obtaining the output power value Pout for each mode. For example, "Pout<Pco2 IL decrease" described in mode 3 increases the output voltage value Vout so that it matches the first set voltage value Vco. As a result, the input current value IL is further decreased and the output power value Pout is reduced. This means that it is suppressed below the set output power value Pco2. "Pout ≤ Pco2 IL decrease" described in mode 5 changes the output voltage value Vout according to the input voltage value Vin. As a result, the input current value IL decreases as the output voltage value Vout increases, and the output voltage value Pout means that the output power is suppressed to the set output power value Pco2 or less.

As shown in FIG. 5, the range in which each mode is selected is in contact with at least one side parallel to the horizontal axis and one side parallel to the vertical axis. Transitions are possible in both directions between modes with contiguous ranges. The arrows shown in FIG. 5 indicate this.

"a: Vin>VH" shown in FIG. 5 indicates that the input voltage value Vin exceeds the set upper limit voltage value VH as condition a. When the mode 1 or mode 7 is set, if the condition a is satisfied, the mode is changed to the mode 9. "b: IL>IH (3.0 A)" represents that the input current value IL exceeds 3.0 A set as the set upper limit current value IH is the condition b. When mode 8 is set, a transition to mode 9 is made when condition b is established. As a result, even if the input power value Pin is less than the input upper limit power value PH and the input voltage value Vin is equal to or less than the set upper limit voltage value VH, if the input current value IL exceeds the set upper limit current value IH, Mode 9 is set. “c: Pin≧PH” indicates that the input power value Pin is equal to or greater than the upper limit input power value PH, which is the condition c. When mode 7 or mode 8 is set, mode 9 is entered when condition c is established.

Hereinafter, each mode will be described in further detail with reference to the explanatory diagrams shown in FIGS. 6 to 9. FIG.

Modes 1 and 2 are modes selected when the converter 1 is started. At the start-up of converter 1, input power value Pin has not been calculated. Therefore, at startup, the control state determination unit 33 determines modes 1 and 2 as selection candidates. Converter state determination unit 34 selects mode 1 or mode 2 depending on input voltage value Vin. If the input voltage value Vin is less than half the first set voltage value Vco, that is, Vin<0.5Vco, converter state determination unit 34 selects mode 2 . If the relationship does not hold and the relationship 0.5Vco≦Vin≦VH holds, converter state determination unit 34 selects mode 1 .

During one cycle, in mode 1, the switch elements Q1 and Q2 are always turned on, and in mode 2, the switch element Q1 is turned on and off, and the switch element Q2 is turned on. As a result, in mode 1, even if the output power value Vout is 0, the input current value IL is increased by turning on the switch element Q2. In mode 2, even if the actual output power value Vout is 0 by turning on the switching element Q2, by turning on/off driving the switching element Q1,
The input voltage value Vin is manipulated to become larger. Henceforth, unless otherwise specified, the contents of driving the switch elements Q1 and Q2 are expressed assuming one cycle.

Mode 3 is selected when the input power value Pin is less than the set input power value Pco1 and the input voltage value Vin is 1/2 or more of the first set voltage value Vco and less than the first set voltage value Vco. This mode is for maximum power control. Basically, in mode 3, priority is given to matching the output voltage value Vout to the first set voltage value Vco by boosting, and the switch element Q1 is turned on and the switch element Q2 is turned on and off. By boosting, the input current value IL increases and the input voltage value Vin decreases, but the input power value Pin increases.

6A and 6B are diagrams for explaining examples of various states of the converter when Mode 3 is set, and examples of the details of driving each switch element. Here, as various states, examples of temporal changes of the input voltage value Vin, the voltage value across the smoothing capacitor Cin, the input current value Iin, the input power value Pin, and the output voltage value Vout are shown. As for the ON/OFF states of the switch elements Q1 and Q2, H (High) indicates ON and L (Low) indicates OFF. These are the same in FIGS. 7 to 9 as well.

The open voltage of the thermoelectric conversion module group TMG corresponds to the input voltage value Vin obtained when the switch element Q1 is turned off. Hereafter, the open-circuit electromotive force is referred to as "open-circuit electromotive voltage Vin0" for convenience.

As shown in FIGS. 4 and 6, in mode 3, the switch element Q1 is always turned on, and the switch element Q2 is turned on and off. As a result, basically, the output voltage value Vout is maintained at the first set voltage value Vco. In FIG. 6, the output voltage value Vout after being smoothed by the smoothing capacitor Cout is indicated by a solid line, and the output voltage value Vout before being smoothed is indicated by a broken line. Accordingly, the output voltage value Vout is shown schematically. This also applies to FIGS. 7-9.

Mode 4 is the maximum power selected when the input power value Pin is less than the set input power value Pco1 and the difference between the input voltage value Vin and the first set voltage value Vco is within a narrow set range. This is the control mode. As shown in FIGS. 4 and 7, basically in mode 4, the switch element Q1 is turned on and the switch element Q2 is turned off, or turned on and off so that the output voltage value Vout matches the first set voltage value Vco. be. As a result, step-up/step-down according to the input voltage value Vin, that is, step-up or step-down of the input voltage value Vin is performed. However, if the maximum power cannot be obtained even if the output voltage value Vout is matched with the first set voltage value Vco, the input voltage value Vin becomes lower than the first set voltage value Vco, as in mode 3. In this manner, the input current value IL is increased to follow the maximum power point at which the maximum power is obtained, and the output voltage value Vout is boosted to the first set voltage value Vco. This mode 4 is a peculiar mode in the first embodiment.

Mode 5 is input power suppression selected when the input power value Pin is equal to or greater than the set input power value Pco1 and the input voltage value Vin is equal to or greater than the first set voltage value Vco and less than the second set voltage value Vch. This is the control mode. In mode 5, the switch element Q1 is turned on and the switch element Q2 is turned off. Therefore, on the condition that the output power value Pout is within the range of the set output power value Pco2 or less and the output voltage value Vout is less than the second set voltage value Vch, the output voltage value Vout depends on the input voltage value Vin. change by The converter state determination unit 34 determines whether or not this condition is satisfied. The input current value IL changes according to the input current value Iin. The input current value IL is approximately equal to the input current value Iin.

Mode 6 is the maximum power control selected when the input power value Pin is less than the set input power value Pco1 and the input voltage value Vin is greater than or equal to the first set voltage value Vco and less than the second set voltage value vch. This mode is for As shown in FIGS. 4 and 8, in mode 6, the switch element Q1 is turned on/off and the switch element Q2 is turned off in order to step down the output voltage value Vout to match the first set voltage value Vco. As a result, the input current value IL increases, the input voltage value Vin decreases, the maximum power point is approached, and the input power value Pin can be increased.

Mode 7 is input power suppression control selected when the input power value Pin is less than the input power upper limit value PH, and the input voltage value Vin is equal to or greater than the first set voltage value Vco and equal to or less than the set upper limit voltage value VH. This mode is for As shown in FIGS. 4 and 9, when the input power value Pin is equal to or greater than the set input power value Pco1 and the input voltage value Vin is equal to or greater than the second set voltage value Vch, mode 5 shifts to mode 7. FIG.

In mode 7, the input voltage value Vin is suppressed below the set upper limit voltage value VH, the output voltage value Vout is made to match the first set voltage value Vco, and the output power value Pout is maintained at the set output power value Pco2. , the switch element Q1 is turned on, and the switch element Q2 is turned on and off. By such driving, the input voltage value Vin is operated to be smaller and the input current value IL is operated to be larger. Therefore, it is possible to keep the output power value Pout close to the set output power value Pco2 while suppressing the input voltage value Vin to the set upper limit voltage value VH or less.

When the input current value IL is increased until the input voltage value Vin becomes less than the first set voltage value Vco, mode 7 shifts to mode 8 . That is, when the set input power value Pco1 or more and less than the second set voltage value Vch, the mode 5 is selected with priority. Mode 8 is the destination of the transition. When the input power value Pin is less than the set input power value Pco1 and the input voltage value Vin is less than the second set voltage value Vch, the mode shifts from mode 7 to mode 6 to switch to maximum power control.

Mode 8 is selected when the input power value Pin is equal to or greater than the set input power value Pco1 and the input voltage value Vin is equal to or greater than half the first set voltage value Vco and less than the first set voltage value Vco. This mode is for input power suppression control. In mode 8, as in mode 7, the switch element Q1 is turned on and the switch element Q1 is turned on so that the output voltage value Vout is matched with the first set voltage value Vco and the output power value Pout is also matched with the set output power value Pco2. Q2 is driven on and off. In mode 8, the assumed input voltage value Vin is smaller than in mode 7. Therefore, the input current value IL is decreased so that the input voltage value Vin approaches the first set voltage value Vco while suppressing the input power value Pin below the set input power value Pco1.

In FIG. 9, "second step-down drive" and "third step-up drive" are shown for each cycle. As a result, FIG. 9 shows that the switch elements Q1 and Q2 are driven in the order of the second step-down drive→the third step-up drive→the third step-up drive for each cycle. The second step-down drive represents that the switch elements Q1 and Q2 are driven in mode 7. FIG. The third step-up drive represents that the switch elements Q1 and Q2 are driven in mode 8. FIG. Accordingly, FIG. 9 shows examples of various states of the converter and examples of the details of driving each switch element when each mode 7 and mode 8 is set.

Mode 9 is a mode for protecting converter 1 by stopping it. Therefore, both switch elements Q1 and Q2 are turned off.

Mode 9 is unconditionally selected when the input power value Pin exceeds the input upper limit power value PH, the input voltage value Vin exceeds the set upper limit voltage value VH, or the input current value IL exceeds the set upper limit current value IH. be.

Mode selection from modes 1 to 9 is performed by the control state determination section 33 and the converter state determination section 34 as described above. That is, when the input electric power value Pin is 0 or a value close to 0, the control state determination unit 33 determines that the control to be executed is start control. Options in the converter state determination unit 34 at this time are mode 1 and mode 2 . When the relationship of Pin<Pco1 is established, the control state determination unit 33 determines that the control to be executed is the maximum power control. At this time, modes 3, 4, 6, and 9 are available as options in the converter state determination unit 34. FIG. When the relationship of Pco1≤Pin, more precisely, Pco1≤Pin<PH is established, the control state determination unit 33 determines that the control to be executed is the input power suppression control. Options in the converter state determination unit 34 at this time are modes 5 and 7-9. However, Mode 7 is an option after Mode 5 is selected, as described above. When the relationship of Pin≧PH is established, the control state determination unit 33 determines that the control to be executed is the protection stop control. Mode 9 is determined by this determination.

The converter state determination unit 34 limits the mode range corresponding to the control method determined by the control state determination unit 33, and selects the mode from the input voltage value Vin or the input current value IL. That is, converter state determination unit 34 selects mode 1 when the relationship of 0.5 Vch≦Vin≦VH is established when start control is determined. Similarly, mode 2 is selected when the relationship Vin<0.5Vco is established.

If maximum power control is determined, converter state determination unit 34 selects mode 3 when the relationship 0.5Vco≦Vin<Vco is established. Similarly, converter state determination unit 34 selects mode 4 when the relationship Vin≈Vco is established, mode 6 when the relationship Vco≦Vin<Vch is established, and mode 9 when the relationship Vin>VH is established. Mode 9 is also selected by the relationship IL>IH.

If the input power suppression control is determined, converter state determination unit 34 selects mode 5 based on the establishment of the relationship Vco≦Vin<Vch. Similarly, converter state determination unit 34 determines mode 7 when the relationship Vch≦Vin<VH is established when mode 5 is selected, mode 8 when the relationship 0.5 Vco≦Vin<Vco is established, and the relationship Vin>VH. is established, mode 9 is selected respectively. Even if input power suppression control has been determined, mode 9 is selected when the relationship IL>IH is satisfied.

A mode selection result is output from the converter state determination unit 34 to the output voltage control unit 35 . As a result, the output voltage control section 35 drives the switch elements Q1 and Q2 according to the selected mode. It should be noted that the modes for ON/OFF driving of the switch elements Q1 and Q2 are not limited to those shown in FIG. Also, the selection conditions for each mode are not limited to those shown in FIG.

Next, referring to FIGS. 10 to 12, in converter 1, when the temperature difference is 90 degrees or more, input power value Pin becomes equal to or greater than set input power value Pco1, and open-circuit voltage Vin0 becomes equal to or greater than second set voltage value Vch. A further description will be given of the control in the case of . FIG. 10 is a diagram illustrating an example of control of output power according to temperature difference. FIG. 11 is a diagram for explaining an example of controlling the output voltage according to the temperature difference. FIG. 12 is a diagram for explaining an example of controlling the output current according to the temperature difference. 10 to 12, the temperature difference is plotted on the horizontal axis. In FIG. 10, the vertical axis represents power, in FIG. 11, voltage, and in FIG. 12, current.

When the input power value Pin becomes equal to or greater than the set input power value Pco1, mode 5 is entered. After that, when the temperature difference further increases, in order to prevent the input voltage value Vin from exceeding the set upper limit voltage value VH and to continue the operation so that the output power value Pout becomes equal to the set output power value Pco2, When the input voltage value Vin exceeds the second set voltage value Vch, mode 7 is entered. In mode 7, as described above, the input current value IL is increased and the input voltage value Vin is suppressed. As a result, when the input voltage value Vin is suppressed below the first set voltage value Vco, the mode shifts to mode 8, and the input power value Pin is maintained near the set input power value Pco1 even if the temperature difference increases.

In FIG. 10, a polygonal line 221 shows an example of temperature difference-power characteristics when the input power value Pin is controlled to be maximized, and a polygonal line 222 suppresses the input power value Pin and sets the output power value Pout. It shows an example of temperature difference-power characteristics when the power value Pco2 is matched. Accordingly, a polygonal line 222 represents a case corresponding to the first embodiment. In the first embodiment, as shown in FIG. 10, when the input power value Pin becomes equal to or greater than the set input power value Pco1, the output power value Pout is maintained at the set output power value Pco2 or less. is suppressed.

In FIG. 11, a polygonal line 231 indicates an example of temperature difference-input voltage characteristics when the switch element Q1 is turned off. A polygonal line 232 represents an example of temperature difference-input voltage characteristics when the input voltage value Vin is controlled to be half the open voltage Vin0. A polygonal line 233 indicates an example of temperature difference-input voltage characteristics when generating a voltage greater than the case of the polygonal line 232, and a polygonal line 234 indicates an example of temperature difference-input voltage characteristics when generating a voltage smaller than the case of the polygonal line 232. ing.

In FIG. 10, it has been explained that the input power value Pin is suppressed. It shows voltage characteristics. A polygonal line 234 in FIG. 11 indicates the characteristics obtained when the input voltage suppression control is performed, and indicates the operation contents in the first embodiment corresponding to the polygonal line 222 in FIG.

In FIG. 12, a polygonal line 241 shows an example of temperature difference-current characteristics when both ends of the thermoelectric conversion module group TMG are short-circuited by turning on both switch elements Q1 and Q2. A polygonal line 242 shows an example of temperature difference-current characteristics when the input current value IL is controlled to be half the short-circuit current value Is. In FIG. 10, it has been explained that the input power value Pin is suppressed. showing characteristics. A polygonal line 244 in FIG. 12 indicates the characteristics obtained when the input voltage suppression control is performed, and shows the operation contents in the first embodiment corresponding to the polygonal line 222 in FIG.

In FIGS. 10 to 12, polygonal lines 232 and 242 show changes in different characteristics when maximum power control is performed in the same case. When switching from the maximum power control to the input power suppression control that suppresses the input voltage based on the input power value Pin and the input voltage value Vin that change with the temperature difference, the respective characteristics are represented by broken lines 222, 234, and 244 changes. Therefore, as shown by the polygonal line 234 in FIG. 11, the polygonal line 222 keeps the input power value Pin within the rating by suppressing the input voltage value Vin as the temperature difference increases when the temperature difference exceeds 90 degrees. ing. At this time, the converter 1 performs a step-up operation, and the output voltage value Vout is maintained at the first set voltage value Vco. When the input current is suppressed, each characteristic changes as indicated by polygonal lines 222, 233, and 243. FIG.

As shown in FIGS. 10 to 12, in the first embodiment, the input power value Pin is maximized when the input power value Pin is smaller than the set input power value Pco1. In the region where Pin≧Pco1, the input electric power value Pin is suppressed using the characteristic of the thermoelectric conversion module TMGz that the input voltage value Vin decreases as the input current value IL increases. In this way, the output power value Pout close to the rating of the converter 1 can be maintained without stopping the thermoelectric conversion module TMG even when the thermoelectric conversion module TMG generates more power than the set input power value Pco1.

In the examples shown in FIGS. 10 to 12, mode 7 is entered when the temperature difference reaches 90 degrees or more. By shifting to mode 7 after switching from maximum power control to input power suppression control, the input voltage value Vin is operated to increase the input current value IL, and does not increase as the temperature difference increases. As a result, changes in characteristics as indicated by polygonal lines 222, 234, and 244 will occur.

1 converter, 2 inverter, 3 microcomputer (control unit, power conversion control device), 4 gate pulse generator, 5 voltage sensor (first voltage detector), 6 voltage sensor (second voltage detector), 7 Current sensor (first current detector) 8 Current sensor (second current detector) 10 Power conversion device 21 Inverter body 31 Maximum load resistance setting unit 32 Input power calculation unit 33 Control state determination unit , 34 converter state determination section, 35 output voltage control section, 36 target setting section, Cin, Cout, CD smoothing capacitor, D1, D2 diode, L inductor, Q1 switch element (first switch element), Q2 switch element ( second switch element), TMG1, TMGn thermoelectric conversion module, TMG thermoelectric conversion module group (power supply).

Claims (7)

A first switch element capable of supplying and interrupting the supply of electric power from a thermoelectric conversion module that converts heat into electric power, and a second switch element capable of short-circuiting between both ends of the thermoelectric conversion module, a converter for stepping up and stepping down the voltage of the electric power by turning on and off the first switch element and the second switch element;
a voltage detector that detects the voltage of the power supplied to the converter and outputs a voltage value;
A first set output voltage value, a set upper limit voltage value set based on the rating of the converter, and a second setting set between the set upper limit voltage value and the first set output voltage value. a target setting unit for setting an output voltage value;
When the voltage value detected by the voltage detector is greater than the second set output voltage value , the power is supplied by the first switch element and the power is supplied by on/off driving of the second switch element. an output voltage control unit that controls stepping down the voltage of
A power conversion device having the first set output voltage value is set for maximum power control;
The output voltage control section controls the voltage value detected by the voltage detector to be greater than the first set output voltage value, and the voltage value detected by the voltage detector to be the second set output voltage. When the power is smaller than the value , the power is supplied by the first switch element and the voltage of the power is stepped down by on/off driving of the second switch element,
The power converter according to claim 1. When the voltage value detected by the voltage detector is less than the second set output voltage value and is greater than or equal to the first set output voltage value, the output voltage control unit switches the first switching element to reduce the voltage of the electric power, and perform control not to short-circuit between both ends of the thermoelectric conversion module by the second switch element,
The power converter according to claim 1 or 2 . The output voltage control unit performs control to cut off the power supply by the first switch element when the voltage value detected by the voltage detector is equal to or higher than the set upper limit voltage value.
A power converter according to any one of claims 1 to 3 . The target setting unit further sets an input upper limit power value based on the rating of the converter as a set value for determining whether or not to cut off the power input to the converter ,
The output voltage control unit turns off the first switch element regardless of the voltage value detected by the voltage detector when the power input to the converter is equal to or higher than the input upper limit power value. performs control to cut off the supply of power by
A power converter according to any one of claims 1 to 4 . further comprising a current detector that detects the current of the power and outputs a current value;
The target setting unit further sets a set upper limit current value as a set value for determining whether or not to cut off the power,
The output voltage control unit controls the first switch element regardless of the voltage value detected by the voltage detector when the current value detected by the current detector is equal to or greater than the set upper limit current value. Control to cut off the power supply by turning it off ;
A power converter according to any one of claims 1 to 5 . A first switch element capable of supplying and interrupting the supply of electric power from a thermoelectric conversion module that converts heat into electric power, and a second switch element capable of short-circuiting between both ends of the thermoelectric conversion module, a voltage detector that detects the voltage of the power supplied to a converter that steps up and down the voltage of the power by on/off driving of the first switch element and the second switch element and outputs a voltage value;
a target setting unit in which a plurality of setting values used for controlling the output voltage to be generated by the converter are set based on a result of comparison with the voltage value detected by the voltage detector;
The electric power is reduced by turning on the first switch element based on a comparison result between each of the plurality of setting values set in the target setting unit and the voltage value detected by the voltage detector. an output voltage control unit that performs control for stepping down the voltage of the electric power by turning on and off the second switch element while supplying the electric power;
A power conversion controller having a

Images