JP2013004683A - Power converter of printed board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide current control and voltage control of high precision.SOLUTION: A power conversion circuit includes a first switch containing a main terminal, a reference terminal, and a control terminal, a second switch or a rectifier, at least one input-side capacitor and output-side capacitor respectively, as well as an inductor. The circuit utilizes voltage generated by current between a mutual connection point and a reference potential, an output, or an input, for controlling or protecting the output. A printed board is employed which has a structure being separated by an air gap, such that a conductor on the printed board which is jointed to a side that is not a mutual connection point among elements at which the voltage occurs, is not connected by the shortest distance to a conductor jointed to a terminal of an input capacitor or an output capacitor connected to any one of a reference potential, an input, and an output, to be the same potential of the conductor on a circuit diagram.

Description

The present invention relates to a power conversion device using a printed board.

A great deal of research and development has been conducted on the power conversion circuit that generates another voltage from a certain voltage source as the semiconductor technology advances.

Among them, a switch using a semiconductor or the like and a circuit using an inductor are used for various voltage conversions such as DC-DC, DC-AC, AC-DC, AC-AC.
There are an infinite number of circuit types, and even if only typical ones of non-insulated chopper methods are cited, BUCK, BUCK-BOOST, BOOST, etc. are frequently used for the purpose of voltage inversion, step-down, step-up, etc. .

Almost the same circuit is frequently used in inverter and motor control.
For example, the BUCK type circuit is used as an inverter of a sine wave output as it is by making the control target voltage an arbitrary waveform that is not direct current and fluctuates over time, for example, a sine wave.

For example, if only two switch parts of a BUCK type DC-DC step-down circuit are prepared, a three-phase inverter is a single-phase AC, three-circuit with a 2 / 3π phase difference. Since the parasitic inductance is involved, it can be said that the circuits are substantially the same.

What assumes a speaker instead of an electric motor as a load of this circuit is called a class D amplifier, and the name only differs depending on the load.

The BOOST circuit is also used as a part of a power factor correction circuit (PFC) of a circuit that generates a direct current from an alternating current input.

In this type of circuit, performance is greatly affected not only by the circuit diagram but also by the shape and positional relationship of the printed circuit board, so many patent applications relating to the printed circuit board and component arrangement have been filed.

For example, in Patent Document 1, a switching element having a main terminal, a control terminal, and a reference terminal is placed on one side, and the reference terminal is connected to the reference voltage terminal of the control element on the opposite side via a through hole. A method of placing a MOSFET on a printed circuit board that prevents malfunction of the switching element is disclosed.

Patent Document 2 discloses a method of blocking electromagnetic noise from entering a voltage detection resistor by providing a conductive foil pattern of a printed board between a coil winding and a detection resistor.

Patent Document 3 discloses an invention in which a spiral pattern is formed on a printed circuit and ringing is suppressed by using the parasitic inductance.

Patent Document 4 discloses a power wiring board that can reduce the wiring inductance in an inverter device or the like and suppress the heat generation of the snubber circuit.

As described above, the method of forming the conversion circuit on the printed board is a very basic circuit with a wide range of use. Therefore, the basic design policy is almost established.

Since these policies are not novel, it is common for control semiconductor manufacturers to provide customers with the best design examples of printed circuit boards.

In particular, control semiconductors for BUCK type DC-DC step-down circuits are in the field where design conditions are severe due to the progress of higher frequency, smaller size and higher efficiency. Examples have become the de facto standard.

For example, Non-Patent Document 1, page 48, page 41, is the most typical one.
In this example, the reference potential terminal of the input capacitor and the reference potential terminal of the second switch are arranged substantially adjacent to each other and are coupled at the shortest distance by a thick copper foil formed on the front side of the printed board. .

Guidance for giving the best design example is often given as a circuit diagram.
For example, as in Non-Patent Document 2, page 27, FIG. 12, an instruction to connect with a conductor having the shortest distance is common sense.

This condition may be difficult to meet in particular in a DC-DC converter circuit with two or more outputs, but the first switch and the input side capacitor are still connected to 1 cm or less as described in section 1 on page 26. I'm telling you.

In item 2, it is instructed to shorten the distance of the conductor connecting the first switch, the rectifier, and the input side capacitor.

Non-Patent Document 3, page 25, 43 discloses an example using a composite part in which a first switch and a second switch or rectifier are enclosed in the same SO-8 type surface mount package.

In this example, the terminals having the same potential are adjacently connected at zero distance, which is the best in the conventional technical guidelines.

JP2009-177040A (P2009-177040A)

JP2002-136142A (P2002-136142A)

JP2009-207350A (P2009-207350A)

Japanese Patent Application No. 3-293654

"PM6685Datasheet", [online], ST Microelectronics, 2007-10-18, Retrievedfrom the Internet: <URL: http: //www.st.com/internet/com/TECHNICAL_RESOURCES/TECHNICAL_LITERATURE/DATASHEET/CD00068881.pdf>.

"LTC3853- Triple Output, Multiphase Synchronous Step-Down Controller", [online], Linear Technology Corporation, 2010-12, Retrieved from the Internet: <URL: http: //cds.linear.com/docs/Datasheet/3853fa. pdf>.

"ISL6227Datasheet", [online], Intersil Americas Inc, 2009-04-09, Retrieved from theInternet: <URL: http: //www.intersil.com/data/fn/fn9094.pdf>.

In the arrangement of Non-Patent Document 1, it is necessary to connect the control terminal via another layer of the printed circuit board when coupled with the PWM control semiconductor.

A through hole is used to connect to another layer, but this involves parasitic inductance and resistance, which reduces the operating speed of the first switch and the second switch, resulting in increased loss.

With the arrangement of Non-Patent Document 3, this problem does not occur.

FIG. 1 shows an example in which the first switch and the second switch are redrawn as separate SO-8 type surface mount packages based on the arrangement of Non-Patent Document 3, which is a useful and established prior art. is there.

On the other hand, as a result of intensive studies, the inventor found a limit associated with this arrangement.

With the recent progress of device technology, the resistance component causing loss has been reduced, and the voltage generated by the current between the interconnection point and the reference potential or the output or input has become minute.

On the other hand, a noise voltage derived from various currents flowing on the circuit is generated on every conductor, and this depends on the arrangement of the conductors. Therefore, the same arrangement is almost constant.

For this reason, in the conventional arrangement, the current detection error increases as the voltage generated by the current between the interconnection point and the reference potential or the output or input becomes smaller.

If this was not solved, the subject that the design became difficult with the reduction in loss was discovered.

Then, after a long trial and error, a conductor arrangement in which the noise voltage derived from various currents flowing on the circuit does not affect the detection of the current has been found.

An object of the present invention is to provide an arrangement for preventing an increase in current detection error even if the resistance component of the element is reduced or the loss is reduced.

In order to achieve the above object, the inventor has conducted extensive studies to determine whether there is an arrangement that does not cause a problem, and as a result, has found an excellent arrangement.

In the apparatus according to the present invention, as a first means, a power conversion circuit, which divides between a stable potential side conductor pattern of an element used for current detection and a smoothing capacitor terminal side conductor pattern of the same potential. In this way, voids are formed.

In this power conversion circuit, various effects are generated by performing current detection. For example, output control or protection is performed using a voltage generated by current.

This power conversion circuit is typically a circuit on a printed circuit board.

The power conversion circuit includes a first switch having a main terminal, a reference terminal, and a control terminal, a second switch having a main terminal, a reference terminal, and a control terminal, or a rectifier having a main terminal and a reference terminal, and an inductor. Things are typical.

Further, a smoothing capacitor having an input side capacitor and an output side capacitor is typical.

In such a circuit, it is advantageous in terms of noise and efficiency that the stable potential side conductor pattern of the element used for current detection and the smoothing capacitor terminal side conductor pattern of the same potential are adjacent to each other, for example, in the shortest distance. However, it is not limited to this.

Either the main terminal or reference terminal of the first switch, one of the main terminal or reference terminal of the second switch or rectifier, and one of the inductor terminals are connected to the interconnection point with a conductor. However, the present invention is not limited to this.

Typically, the input is connected to the main terminal or reference terminal of the first switch, the main terminal or reference terminal of the second switch or rectifier, or any terminal selected from the terminals of the inductor. It is not limited to.

Typically, but not limited to, one of the main terminal or reference terminal or inductor terminal of the remaining switch or rectifier not connected to the input is connected to the reference potential by a conductor.

The remaining main terminal or reference terminal or inductor terminal is typically connected to the output, but is not limited thereto.

Typically, the input side capacitor is connected to the reference potential and the input, and the output side capacitor is connected to the reference potential and the output. However, the present invention is not limited to this.

Also, it has one stable potential selected from a reference potential or an output or input.

The power conversion circuit controls and protects the output using the voltage generated by the current between the stable potential and the interconnection point.

This voltage is also generated by the impedance or resistance component of the switch or rectifier or inductor or other element or parasitic element on the current path.

The conductor pattern of the printed circuit board joined to the stable potential side of the element where the voltage is generated and the conductor pattern of the printed circuit board joined to the terminal of the smoothing capacitor to be the stable potential of the same potential on the circuit diagram are the shortest. It has a structure separated by voids so as not to be coupled at a distance.

On the other hand, since the voltage generated by the current is very small, there are many noise voltages associated with switching in the power conversion circuit. Therefore, it is not easy to specify the path of the noise voltage that affects the weak signal.

However, conversely from the fact that the configuration of the present invention is effective, the current flowing through the terminals of the smoothing capacitor has an adverse effect, and it is considered that blocking it by the air gap acts.

As a second means, in addition to the first means, the circuit element may be mounted only on one side.

What is mounted only on one side is not limited to the circuit element.

In particular, not only the circuit element but also a control element that monitors the voltage and current of the circuit element and gives a command to the control terminal according to the value may be coplanar with the circuit element.

By setting the same surface, for example, a positive influence can be expected on the operation of the control terminal. For example, if wiring can be performed without going through the through hole, wiring inductance and resistance can be reduced, and the switch speed is improved.

As a third means, in addition to the first or second means, the surface on which the circuit element is not mounted may be a reference potential or a conductor shield of input or output potential.

As the conductor shield, a conductor used for a printed board, generally, a copper foil of 10 μm, 35 μm, 70 μm, and 200 μm can be used as it is, but is not limited thereto.

In the case of mounting on only one side, it is possible to easily prepare a space for conductor shielding by making an effort not to pass the wiring through the unmounted surface. This shield is effective not only for noise countermeasures but also as a good heat conductor.

As a fourth means, in addition to any one of the first to third means, a current feedback PWM using a MOSFET of 30 milliohms or less as a switch or 30 milliohms or less as an inductor, the voltage generated by the current May be taken out by differential wiring.

Current feedback PWM is a PWM control method that determines not only the change in output voltage but also the change in output current to determine the pulse width. The voltage generated by the output current itself or the current linked to the output current This is a control method in which the responsiveness is improved by adding or subtracting from the feedback voltage value of the control loop of the voltage feedback PWM.

An independent resistor may be used as a current detection element that extracts a voltage generated by a current linked to the output current, but is generally parasitic on the first switch or the second switch, or the rectifier or inductor element. In many cases, a resistance component or a resistance component of a conductor is used.

Since the voltage value generated in them is very weak, when leading from both ends of the element to the control element, a pair of wires taken from both ends are taken out as adjacent parallel wires so that they are not easily affected by noise. It is taken out by wiring.

For example, when a MOSFET of 30 mΩ or less is used as a switch, the voltage is only about 30 mV per 1 A, and the MOSFET is selected from a range such as 10 mΩ, 5 mΩ, 1 mΩ, 0.5 mΩ, 0.1 mΩ, 0.01 mΩ. When is used, the detection voltage becomes weak, so the present invention is very effective.

When the resistance component of the inductor or conductor is used as the current detection element, the MOSFET can be read as the resistance component of the inductor or conductor.

As a fifth means, in addition to any one of the first to fourth means, any of a BUCK type converter, a BUCK-BOOST type converter and a BOOST type converter using the same may be used.

In the case of a BUCK type converter, the first switch is a MOSFET and the main terminal is input, the reference terminal is connected to the interconnection point, the second switch is a MOSFET and the main terminal is the interconnection point, the reference terminal is the reference potential, and the inductor is A synchronous rectification configuration connecting between the interconnection point and the output may be used, and a Schottky diode may be used as the rectifier, but the invention is not limited to this.

In the case of a BUCK-BOOST type converter, the first switch is a MOSFET and the main terminal is input, the reference terminal is connected to the interconnection point, the second switch is a MOSFET and the main terminal is the interconnection point, the reference terminal is output, the inductor Are connected between the interconnection point and the reference potential, and a synchronous rectification configuration may be used, or a Schottky diode may be used as the rectifier, but the invention is not limited to this.

In the case of a BOOST type converter, the first switch is a MOSFET and the main terminal is connected to the interconnection point, the reference terminal is connected to the reference potential, the second switch is the MOSFET and the main terminal is output, the reference terminal is the interconnection point, and the inductor is A synchronous rectification configuration may be used, which is connected between the input and the interconnection point, and a Schottky diode may be used as the rectifier, but is not limited thereto.

In any converter, when the second switch is used as the current detection element, the voltage between the main terminal and the reference terminal can be taken out by the differential wiring.

When the first switch is used as the current detection element, the voltage between the main terminal and the reference terminal can be taken out by the differential wiring.

When an inductor is used as the current detection element, the voltage at the two terminals can be taken out by differential wiring.

By taking out with the differential wiring, it seems that in the theory on the desk, noise mixing and current detection error are eliminated without using the present invention, but in reality, the differential signal receiving side, for example, the differential amplifier of the control semiconductor There is a limit to ability. According to the present invention, the current detection error can be reduced without preparing an ideal differential amplifier.

As a sixth means, in addition to any of the first to fourth means, an inverter, a converter, and a power amplifier using the means may be used.

In these circuits, the element current value, the output voltage value, and in some cases, another command voltage is added or subtracted, or the integral control or the differential operation is performed to perform PWM control.

That is, for example, it is obvious that such a circuit can be configured by replacing the feedback voltage value of the control loop of the current feedback PWM with a control element having a function of adding a command voltage.

Circuits that perform PWM control by adding or subtracting these element current values, output voltage values, and, in some cases, other command voltages, or performing integral or differential calculations, are often composed of continuous operational amplifiers. However, it may be a discrete computing machine.

Furthermore, these circuits may be used by being incorporated in a device for controlling an electromagnetic force device such as an inverter for a motor or a power amplifier for a speaker.

In these devices, since the error of the element current value flows into the output voltage value, it is particularly required to reduce the error of the element current value.

In the case of a discrete computing device, the present invention with less occurrence of instantaneous errors is suitable for the convenience of sampling instantaneous values.

As a seventh means, in addition to any one of the first to sixth means, for one main power supply, the first to sixth circuits, a power conversion circuit having an inductor and a switch, and another pulse load May be connected in parallel.

The parallel connection may be in the same substrate, or circuits on separate substrates may be connected by an arbitrary method such as a bus type, a star type, or a crossover wiring with an electric wire or the like, and is not limited.

In parallel connection, the smoothing capacitor on the input side is often connected to another pulse load on the circuit diagram.

In such a case, fluctuations in the charge of the smoothing capacitor due to other pulse loads may have an adverse effect, but if they are divided according to the present invention, the influence can be reduced.

According to the present invention, the output quality is improved.

As the element technology advances, the resistance component causing loss is reduced, and the voltage generated by the current between the interconnection point and the reference potential or the output or input is reduced.

On the other hand, a noise voltage derived from various currents flowing on the circuit is generated in the conductor.

This causes a current detection error.

According to the present invention, this current detection error can be reduced.

As a result, the current is accurately controlled, and finally the output voltage and current are stabilized.

Since the inverter, converter, and power amplifier according to the present invention lead to accurate output according to the command voltage, the effect of improving the control quality can be obtained.

When mounted on only one side, there is an effect that it is not necessary to perform mounting work on the opposite side.

If the surface on which the circuit element is not mounted is a conductor shield of a reference potential or an input or output potential, the generation of noise can be suppressed and the influence of noise can be reduced.

When the present invention is used for current feedback PWM, there is an effect that improvement in current detection accuracy is directly linked to improvement in voltage accuracy.

When a parasitic resistance component or a conductor resistance component is used as the current detection element, a new resistance component is not added, resulting in an effect of reducing loss.

When incorporating and using an electromagnetic force device such as an inverter for a motor or a power amplifier for a speaker, it is important to accurately measure the electromagnetic force, that is, the current in such a device and reflect it in the control target. Therefore, the present invention capable of detecting an accurate current brings about an effect of improving the electromagnetic force control quality.

If the detection error can be reduced, the filter and the like can be simplified, and an unexpected effect that the responsiveness can be improved can be expected.

Even in the case where the first to sixth circuits, a power conversion circuit having an inductor and a switch, and another pulse load are connected in parallel to one main power source, according to the present invention, the output quality is also improved. Will improve.

Many loads, including circuits with switches of the present invention, are essentially pulse loads.

When a plurality of these are connected, it is expected that they will affect each other due to a pulse current from another circuit.

As one of the influences, a current detection error occurs, but the present invention is effective as a countermeasure because it reduces the current detection error.

It is the layout by a prior art. (Problems to be solved by the invention) It is explanatory drawing of the circuit which showed the implementation method. (Mode for carrying out the invention) It is the layout which showed the implementation method. (Mode for carrying out the invention)

The best mode for carrying out the present invention will be described below. FIG. 2 is a circuit diagram for carrying out the invention. Note that the control terminal of the switch is omitted.

In the figure, VI is an input, VR is a reference potential, VO is an output, CI is an input side capacitor, and CO is an output side capacitor.

A is any one of the first switch, the second switch or rectifier, and the inductor.

One of the remaining two types corresponds to B.

C is the last one.

That is, although six circuit configurations are possible, three of these are often used and are called by name.

When A is an inductor and B is the first switch, a BOOST converter is obtained.

If A is the first switch and B is the second switch or rectifier, a BUCK type converter is obtained.

When A is the first switch and B is an inductor, a BUCK-BOOST type converter is obtained.

A circuit in which A is a second switch or rectifier, or a circuit in which B is a second switch or rectifier when A is an inductor corresponds to a circuit in which the above three types of inputs and outputs are reversed.

FIG. 3 is a layout diagram illustrating a method of implementing the BUCK type converter.

Reference numerals 201, 202, and 210 are positions where the input-side capacitors are arranged, and are generally arranged at any one location, but a plurality of them may be arranged.

The features of the present invention will be described by taking 202 as an example.

203 is a second switch corresponding to 103 in FIG. 1 and B in FIG. 2, and 202 is an input side capacitor CI corresponding to 101.

In FIG. 1 according to the prior art, 103 and 101 are arranged adjacent to each other, and accordingly, the reference terminal of 103 and the terminal of 101 are arranged next to each other, thereby realizing the shortest distance wiring by copper foil on the same surface. is doing.

On the other hand, in the arrangement according to the present invention, even if 203 and 202 are in a positional relationship that enables wiring at the shortest distance by the copper foil on the same plane, the distance between 203 from the left side at the top of 202 in FIG. By providing a gap, direct electrical coupling is blocked.

As a means of not being coupled at the shortest distance, it is most convenient to create a void removed by etching the copper foil on the printed circuit board. The present invention is not limited to such voids, and other known techniques may be used.

Since the required gap is the same potential on the circuit diagram on both sides, a minute gap is sufficient.
In general, the space that can be manufactured with a printed board is described in the manufacturing specification as 0.0254 mm as 1 mil, but 1, 2, 4, 6, 8, 10, 12, 16, 20, 40 mil is common. In practice, these are lower limits, but are not limited.

If the gap is increased, the distance between CI and B is increased, so that the parasitic inductance and resistance are increased and the function of CI is lowered. If it is 0.5 mm, there is no problem in many applications, but this problem increases as the distance from 1, 2, 4, 8, 10, 15, 20, 40 mm increases.
In practice, these are upper limits, but are not limited.

Since these wirings need to be connected to each other, in the drawing, they are connected to the copper foil 209 having the reference potential on the back surface by through holes, but in short, it is only necessary to be conductively connected. Any other conductor may be used.

Of course, it is also possible to form a circuit pattern that does not pass through the back surface or the through-hole, but on the same surface so as not to have the shortest distance.

In some cases, the output-side capacitor can be arranged with the same idea.

The reference potential VR (O) terminal of the output side capacitor 105 in FIG. 1 is connected in the shortest distance on the same plane as 101 and 103.

On the other hand, like the reference potential VR (O) terminal 205 in FIG. 3, a gap may be provided so that they are not connected at the shortest distance on the same plane. Of course, the gap may be effectively used by interrupting another wiring, as shown by the thick solid line in FIG.

As another wiring, a line for driving the control terminal and a wiring for extracting a voltage generated by a current flowing through the element in order to detect a current flowing through the element are typical.

Since the wiring for taking out the voltage generated by the current is a weak voltage, a pair of differential wirings are used.

The line for driving the control terminal requires extremely low resistance and low parasitic inductance to reduce the loss of the switch.Therefore, without using a through hole, the surface of the copper foil is sometimes paired with the reference terminal side. It is preferable to draw out with the line which became.

The air gap in the present invention is also useful in providing these wiring spaces.

This is effective for reducing the loss of the switch.

In addition to the effect of the air gap itself, an improvement in detection accuracy of the current flowing through the element can also be expected due to a secondary action resulting from an improved degree of freedom in the location where the differential wiring can be drawn.

In the practice of the present invention, it is only necessary to provide a gap, so the position of the input side capacitor is not limited to 202.

You may move to 202 or 210, and you may arrange two or more in the arbitrary positions chosen from these places.

In addition to the input capacitor or the output capacitor terminal, a third parasitic element is connected to the conductor on the printed circuit board joined to the non-interconnect point of the switch or rectifier or inductor terminal where the voltage generated by the current is generated. Even if a capacitor or an intentionally small capacitor is connected, the essence of the invention is not impaired.

This small capacitor is 207 in FIG. 3 and is basically in a state where the invention is not implemented, but it is clear that there is a parasitic capacitance at this position, avoiding patents, preventing general noise, etc. It is obvious that the essence of the invention is not impaired even if a small capacitor intentionally connected for the purpose of the present invention is connected.

This small capacitor 207 should not be larger than 202 in view of the nature of the invention.
Otherwise, the input side capacitor will be directly connected to the 203 reference terminal.

The ratio of the capacities of 207 and 202 may be 1: 1, 10: 1, 100: 1, 10000000: 1, for example, 1 μF to 1000 μF and 100 pF to 1 μF.

As the input side capacitor, a multilayer capacitor, particularly a multilayer ceramic capacitor, in particular 0.1 μF to 1000 μF, particularly 1 μF to 100 μF, is particularly suitable in the present technology, but the present invention is not limited to this. Electrolytic capacitors using molecules, tantalum electrolytic capacitors, aluminum electrolytic capacitors, film capacitors, and other elements can be preferably used, and may be mixed.

The output capacitor can be selected in the same way as the input capacitor.

The first switch 204 is not particularly limited as long as it has a switching action.

A typical example is an N-MOSFET, in which the reference terminal is a source, the main terminal is a drain, and the control terminal is a gate. However, the present invention is not limited to this.

For example, an NPN transistor, a P-MOSFET or an IGBT may be used. Moreover, it is not limited to a semiconductor element, The element which has all switch actions like an optical device, a vacuum tube, and a mechanical contact can be used.

The ability of a switch, such as a MOSFET, is expressed as a low drain-source resistance in the conducting state as a switch.

Conventionally, it has been 200 mΩ or 100 mΩ, but in recent years, technological development for reducing the loss has progressed such as 30 mΩ, 10 mΩ, 5 mΩ, 1 mΩ, 0.5 mΩ, 0.1 mΩ, and 0.01 mΩ.

When the resistance between the drain and the source is low, the detection voltage becomes very weak when used as a current detection element, and current detection may be difficult.

Since the present invention relates to improvement of current detection accuracy, it is effective in such a case.

In other words, there is an effect that a MOSFET having high ability can be used.

The external dimensions of the switch are becoming smaller due to improved performance. In the past, TO-220 was often used, but small packages such as D-PAK and SO-8, and SOT-23 and SOT-232 have appeared.

The withstand voltage of the switch may be determined according to the input and output voltages. Among the devices that are generally available at present, IGBTs of about 3 kV and MOSFETs of 900 V class have been used. Wide-gap semiconductors such as SiC are expected for high breakdown voltage products, and 5 kV, 10 kV, and 1000 kV may be realized by other technological advances. There are 600V to 450V for commercial power lines, and 100V and 60V are often used for motor control. Since the development of low-voltage products such as 30V, 20V, and 10V as semiconductor power sources is progressing, those with a breakdown voltage of 5V, 1V, and 0.5V may appear.

The current flowing through the switch tends to increase as the performance of the semiconductor increases, but products in a wide range of 3A to 8A, 16A, 25A, and 50A are used even in the SO-8 size. Some small products are 0.1A. As a large product, there is a possibility that development will proceed to 100A, 500A, 1000A, and 10000A in the future.

The same applies to 203.

It is clear that a rectifier can be used instead of 203.

Although not limited, a diode having a reference terminal as an anode and a main terminal as a cathode can be preferably used.

A Schottky type is often used as the diode, but a high-speed Si diode or other element can be preferably used. MOSFET parasitic diodes are often used, but are not limited to silicon semiconductor elements, and elements having any rectifying action such as vacuum tubes and mercury rectifiers can be used.

In many cases, an independent Schottky diode is used in combination with a MOSFET having a parasitic diode. However, this is merely the reinforcement of the function of the second switch by a rectifier, and it is obvious that it is within the scope of the present invention.

The reference potential is generally ground, but may be a positive or negative constant voltage, or an AC voltage may be applied, and is not limited.

The input is most commonly connected to a positive voltage power supply with respect to the reference potential, but is not limited thereto, and may be a negative voltage or an AC voltage.

The output is essentially not limited because a voltage determined by the operation of the switch is output, but if representative numbers are given, positive or negative DC 0.5V, 1V, 3V to 5V, 12V 24V, 48V, 100V, 280V, 500V, and 1500V are often controlled, and the switch operation may be controlled with an AC waveform in a similar voltage range as a target.

A multilayer ceramic capacitor is preferably used as the capacitors 201, 202, 205, and 210, but a tantalum capacitor, a conductive polymer capacitor, an electrolytic capacitor, a film capacitor, and other capacitors may be used instead.

Many of these recent capacitors have very low equivalent series resistance, and are 50mΩ, 20mΩ, 10mΩ, 5mΩ, 2mΩ, 1mΩ, 0.1mΩ, 0.01mΩ, and the design has been improved to improve performance. There is also a problem.

An inductor such as 206 is well known in which a conductor is wound around an arbitrary magnetic body such as a ferrite or iron powder molded body. Many of these have very small equivalent series resistance, and there are 10Ω and 1Ω depending on the application, but the reduction progressed to 50mΩ, 20mΩ, 10mΩ, 5mΩ, 2mΩ, 1mΩ, 0.1mΩ, 0.01mΩ, There are also design challenges associated with improved performance.

Detection of the inductor current by measuring both-end voltage becomes difficult as the equivalent series resistance is reduced, and the effect of the present invention that the current detection accuracy is improved is effective.

Since the difference between the case where the voltage generated by the current flowing through the second switch is detected and the detection of the inductor current is the selection of which element in FIG. 2 is measured, for example, the first switch is used. Obviously you can also.

Considering the replacement relationship of FIG. 2ABC by detecting the inductor current, the gap corresponds to the gap around the VR (O) 205 in FIG.

Obviously, such a mathematical combinatorial replacement can be used in other types of circuits.

For example, in the BUCK-BOOST type in which the positional relationship between the inductor 106 and 103 shown in FIG. 1 is changed, the present invention can be applied by replacing 203 and 206 in the arrangement shown in FIG.

Alternatively, in the case of a BOOST type in which the positional relationship between the inductor 106 and 104 in FIG. 1 is changed, the present invention can be applied by replacing 204 and 206 in the arrangement of FIG.

The number of through holes such as 208 may be one each as a minimum number, but a plurality of through holes may be arranged for the purpose of reducing the resistance component and the inductance or for the purpose of heat dissipation.

The back surface of the substrate such as 209 is effective for noise countermeasures and heat dissipation when a copper foil of a reference potential is used. However, other constant potentials such as input and output potentials may be used, and arbitrary patterns may be formed. .

If the back surface is only a copper foil having a reference potential, it is not necessary to consider a potential difference when attaching a heat sink to the back surface side, and it is convenient because it is flat.

Although the board | substrate which mounts a circuit element is not specifically limited, The two-layer board | substrate which affixed copper foil on both surfaces of the plate-shaped insulator is suitable. In addition, it is known that the use of a multilayer substrate having a larger number of layers, for example, a two-layer substrate and a four-layer substrate in which both sides of a plate-like insulator are bonded to each other has an improvement in wiring density and other advantages. ing.

When the cost requirement is very severe, according to the present invention, it is also possible to carry out with a single-sided substrate having a copper foil pattern only on one side. For example, in FIG. 3, the reference potential terminals 202, 205, 208, 207, and 210 are connected via a copper foil on the back surface connected by a through hole. It is obvious that the conductors may be connected to each other by an arbitrary conductor such as a tin-plated wire or a copper wire instead of the copper foil on the back surface.

For example, a tin-plated wire to 207 starting from 205 and a conductor wiring to 202, 208, 210 may be used.

In addition to the circuit element, a control element may be mounted on the same surface as the circuit element.

The control element is an element that monitors the voltage and current of the circuit element and gives a command to the control terminal according to the value.

By using the same surface, generally, the mounting operation can be completed at a time, so that the manufacturing cost can be reduced.

Having the same surface also has other effects. For example, if the command signal can be transmitted only by wiring on the same surface, the operation of the command signal becomes faster, which is effective in reducing circuit loss.

Highly accurate current control and voltage control can be provided.

101 Input side capacitor placement position 102 Input side capacitor placement position 2
103 Second switch 104 First switch 105 Output-side capacitor 106 Inductor 107 Copper foil pattern 108 Through hole 109 Reference potential copper foil (back surface)

201 Input side capacitor placement position 202 Input side capacitor placement position 2
203 2nd switch 204 1st switch 205 Output side capacitor 206 Inductor 207 Small capacitor 208 Through hole 209 Reference potential copper foil (back surface)
210 Input capacitor position 3

VI Input VO Output VR Reference potential VR (I) Input side reference potential terminal VR (O) Output side reference potential terminal CI Input side capacitor CO Output side capacitor A Element B Element C Element

Claims (7)

A power conversion circuit in which a gap is formed so as to divide between a stable potential side conductor pattern of an element used for current detection and a smoothing capacitor terminal side conductor pattern of the same potential. 2. The circuit element according to claim 1, wherein the circuit element is mounted only on one side of the printed board. 3. A circuit board according to claim 1, wherein a surface on which no circuit element is mounted is a conductor shield of a reference potential or an input or output potential. 4. A current feedback PWM using a MOSFET of 30 milliohms or less as a switch according to claim 1, wherein a voltage generated by the current defined in claim 1 is taken out by a differential wiring. Any one of a BUCK type converter, a BUCK-BOOST type converter, and a BOOST type converter using claims 1 to 4. An inverter, a converter, and a power amplifier using the first to fourth aspects. A main power source in which the circuit according to any one of claims 1 to 6, a power conversion circuit having an inductor and a switch, and another pulse load are connected in parallel.

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