Warm hints: The word in this article is about 3500 and reading time is about 18 minutes.
Summary
This paper presents a new design of a high-power adjustable switching power supply. Using Buck-type switching power supply topology, with a single PWM output, MC33060 as a control IC, and dual output IR2110 driver chip, We can design a high-voltage high-power switching power supply as an effective solution to adjustable high-voltage Switching power supply circuit. Which can solve the problem effectively that in the non-isolated topology, the common switching power supply can not reach high limits, and attached with over-current protection usage. In this paper, based on the application of MC33060, I present the design method of adjustable switching power supply, then the composition of the system and the function of each part are explained in detail. Finally, the characteristics of the system are summarized.
Catalog
Ⅰ Switching Power Supply Introduction
As an alternative to linear regulated power supplies, switching power supplies have become increasingly sophisticated in use and implementation. The integrated technology has driven electronic devices to be smaller and more intelligent. the new electronic devices require a switching power supply with a smaller size and lower noise interference in order to achieve integration and integration. For small and medium-power switching power supply is monolithic integration, but in the field of high-power applications, because of its power loss is too large, it is difficult to make monolithic integration, had to be based on its topology to ensure that the power of the various parameters Try to reduce the system size.
Here is some information about high-power switching power supply’s technical indicators. The high-power switching power supply is mainly used in high-frequency power system switching power supply, the technical indicators must be very high and accurate.
Determine the technical indicators are as follows, here attached an example model of the High-power adjustable switching power supply technical characteristics diagram.
-
1. Input voltage: 380_ + 20%;
-
2. Grid frequency: 50Hz_ + 10%;
-
3 power factor: 0.93 above;
-
4. Input over-voltage alarm: 437V_ + 5V;
-
5. Enter the brown-out alarm: 320V_ + 5V;
-
6. Output nominal voltage: 220V;
-
7. Output voltage range: 176-286V;
-
8. Output ripple voltage: 10mV;
-
9. Output rated current: 5A;
-
10. Output over-voltage protection: 325V + _5V;
-
11. Output under-voltage protection: 195V + _5V;
Model
|
|
ANSXYD(X-voltage Y-current)
|
Input
|
voltage
|
Single-phase: AC220V±15% or AC110V±15%
|
Three-phase: AC380V±10%(more than 8KW)
|
frequency
|
AC380V±10%(8KW以上)
|
voltage
|
0-1000V
|
Output
|
current
|
0-100000A
|
power
|
Voltage value × current value
|
Display
|
|
LED digital tube
|
Source effect
|
voltage
|
≤0.2% effective value
|
current
|
≤0.2% effective value
|
Temperature drift
|
voltage
|
≤ 0.03% rms / ℃
|
current
|
≤ 0.03% rms / ℃
|
Time drift
|
voltage
|
≤ 0.5% effective value
|
current
|
≤ 0.5% effective value
|
Ripple
|
|
≤0.3% 10mV(rms)
|
Noise
|
|
≤65db
|
Efficiency
|
|
≥0.85
|
Protection ability
|
|
Input over/under voltage, output voltage limit, current limit, over current, over-voltage, over-temperature and so on
|
Communication Interface
|
|
4-20mA, 0-10V analog RS-232 / RS485 communication interface
|
Cooling method
|
|
Smart air / forced air cooling
|
Temperature
|
|
﹣10℃~40℃
|
Humidity
|
|
10%~90% RH
|
1.1 High-power Power Supply Characteristics
Regulated power supply technical indicators can be divided into two categories: one is the characteristic indicators, such as output voltage, output current and voltage regulation range; the other is the quality indicators, reflecting the pros and cons of a regulated power supply, including stability, Equivalent internal resistance (output resistance), ripple voltage and temperature coefficient.
1.2 DC Power Supply Characteristics of Indicators
-
(1) the maximum output current. It depends on the main regulation of the maximum allowable working current and the transformer capacity and the maximum diode rectifier current.
-
(2) Output voltage and voltage adjustment range. This can be determined according to the requirements of the user. For a device that needs a constant power supply, the regulation range of the regulated power supply is preferably smaller. And once the voltage value is adjusted, it’s better not to be changed anymore. For the adjustable output voltage power supply, the output ranges from most of the zero-volt adjustment, usually requiring a wider range of voltage regulators, and continuously adjustable.
-
(3) protection features. In the DC power supply, when the load current overload or short circuits, the regulator will be damaged. Therefore, fast response overcurrent protection circuits must be used. In addition, when the regulator current fails, the output will appear the phenomenon of voltage is too high, which will be harmful to the load. Therefore, it also requires over-voltage protection circuit.
-
(4) Efficiency. A regulated power supply is a transducer, therefore, there are also energy conversion efficiency issues. Improve efficiency is mainly to reduce the power consumption adjustment tube.
Here is a specific explanation about adjustable switching power supply:
This is a tutorial on feedback resistors in DC-DC converters and how to build a high current adjustable power supply using an LM2678
Ⅱ Typical Switching Power Supply Design
The switching power supply generally consists of Pulse Width Modulation (PWM) control IC (Integrated Circuit) and power devices (power MOSFET or IGBT)。 It meets three conditions: the switch (the device works in the switch non-linear state), the high frequency (The device operates at high-frequency non-close to the upper frequency of the low frequency) and DC (power output is the DC instead of AC).
2.1 Control IC
Take MC33060 as an example to introduce control IC.
The MC33060 is a high-performance, voltage-driven pulse-width modulator manufactured by ON Semiconductor and operates from -40 ° C to 85 ° C with a single-ended fixed-frequency output. Its internal structure is shown in Figure 1 [1], the main features are as follows:
-
1) Integrated pulse width modulation circuit
-
2) Built-in linear sawtooth oscillator, the external components only one resistor a capacitor;
-
3) Built-in error amplifier;
-
4) Built-in 5V reference voltage, 1.5% accuracy;
-
5) adjustable dead zone control;
-
6) Built-in transistor provides 200mA drive capability;
-
7) Undervoltage lockout protection
Figure 1 MC33060 internal structure
Its operating principle is described briefly: MC33060 is a fixed frequency pulse width modulation circuit, a built-in linear sawtooth oscillator. The oscillation frequency can be adjusted by an external resistor and a capacitor, the oscillation frequency as (2-1) type:
The width of the output pulse is achieved by comparing the positive-polarity sawtooth voltage on capacitor CT with the other two control signals. The output of the power transistor Q1 is controlled by a NOR gate, which is when the sawtooth voltage is greater than the control signal.
When the control signal increases, the width of the output pulse will be reduced, the specific timing see the following figure
Figure 2 MC33060 timing diagram
Control signals inputs from the outside of the integrated circuit, along the way to the dead time comparator, then to the error amplifier input. The dead-time comparator has an input offset voltage of 120mV which limits the minimum output dead time to approximately 4% of the sawtooth period, ie, the maximum output-driven duty cycle is 96%. When the dead-time control input is terminated, the fixed voltage (in the range of 0-3.3V) can generate additional dead time on the output pulse.
Pulse Width Modulation. The comparator provides a means for the error amplifier to regulate the output pulse width: when the feedback voltage changes from 0.5V to 3.5V, the pulse width of the output drops from zero to the maximum on the percentage determined by the dead band. The two error amplifiers have a common-mode input range from -0.3V to (Vcc-2.0), as perceived by the power supply's output voltage and current. The output of the error amplifier, which is often high, is OR'ed with the inverting input of the pulse width modulator. It is this type of circuit configuration that allows the amplifier to dominate the control loop with minimal output.
2.2 DC/DC Power Supply Topology
DC / DC power topologies are generally divided into three categories: buck, boost and buck-boost. Here to step-down topology, simplified renderings as shown in Figure 3 below. Output and input with the same polarity, the input current ripple, the output current ripple small, simple structure.
Figure 3 Bulk step-down chopper circuit
In the switch turn-on time, the input power supply to the load and inductor; switch off, inductor energy stored in the freewheeling circuit through the diode to ensure continuous output. The load voltage satisfies the following relation (2-2):
2.3 Typical Circuit and Parameter Design
The typical circuit is shown in Figure 4
Figure 4 MC33060 step-down chopper circuit
MC33060 as the main control chip switch on and off, from the internal structure of the function we can see that within the MC33060 has a +5 V reference voltage is usually used as two inverting comparator reference voltage. The design of comparator of pin 1 and pin 2 is used as feedback of the output voltage, the comparator of 13 feet and 14 feet is used for detecting whether the electric current of the switch tube is overcurrent. 2 feet in the circuit is connected to the reference voltage through an anti-phase circuit.
And step-down output feedback flows through a phase connected to the MC33060 1 foot. When the circuit is in working condition, 1 foot and 2 feet voltage will be compared with each other, according to the difference between the two to adjust the output waveform pulse width, to achieve the purpose of control and stable output.
Overcurrent protection circuit 0.1 ohm rated power of 1W power resistor as a sampling resistor, the current flow point, the sampling resistor voltage of 0.1V.14 feet as a sampling point, so the 13-pin reference voltage by the Vref points Pressure set to 0.15V, compared to 0.1V leaves some room. When the sampling voltage is higher than the set value, MC33060 will automatically protect and turn off the PWM output. The protection point is also related to the control signal of the 3-pin. According to the functional analysis of this pin, the integration feedback circuit is selected so that the voltage of the Comparator pin is always within the normal range (0.5V-3.5V) when the buck circuit is under no- within.
The frequency of the output PWM waveform is determined by the capacitance of pin 5 and the resistance value of pin 6. The step-down circuit adopts the waveform frequency of 25KHz, selects the 1nF capacitor with CT value, and the common resistor with RT of 47K meets the design requirements.
Ⅲ The System Design
The design uses a DC (Direct Current) / DC converter circuit buck topology. Input is 220VAC and 0-10V adjustable DC voltage, the output is adjustable 0-180V, the maximum output current up to 8A. The system block diagram is shown in Figure 5 below. In the design of a high-power switching power supply, in order to prevent the surge current surge at start-up, the soft-start circuit is generally used, but this article doesn’t focus on the type.
Figure 5 system block diagram
3.1 Rectifier Filter Circuit
Full-bridge rectifier circuit, shown in Figure 6 below. Output current requirements up to 8A. Considering the power loss and a certain margin, we can choose the 10A square bridge KBPC3510 and 10A fuse. The rectified voltage rises up to 310V, using two 250V / 100uF capacitors for filtering. In the figure below, switch S1 and resistor R1 in parallel act as a "soft-start" part, which will not be explained in detail here. a detailed soft-start design can be seen in another article named a variety of soft-start switching power supply designs.
Figure 6 rectifier circuit
The MC33060 control circuit and the input regulation circuit are shown in Figure 7-1 and Figure 7-2, the selected MC33060 is used as the control IC, the peripheral device selection will not repeat them here. Refer to the typical circuit design parameter selection section. Comparator 1 is used for voltage sampling, comparator 2 is used for current sampling. Input adjustable voltage followed by the partial pressure into the negative side of the comparator usually used as a reference voltage control power output size.
Figure 7-1 MC33060 Control circuit
Figure 7-2 input adjustment circuit
3.3 Reverse Delay Drive Circuit
Inverting delay drive circuit is shown in Figure 8 below. The driver chip in the circuit adopts the IR2110 from the International Rectifier (IR) Company of the United States, which includes not only the basic switch unit and drive circuit, but also the protection control function combined with the external circuit. The floating channel design makes it possible to drive the switch in the bus voltage is not higher than 600V. Its internal is equipped with Undervoltage protection. Combined with the external circuit, you can easily design over-current, over-voltage protection, so do not need Additional over-voltage, under-voltage, over-current protection circuit simplifies the circuit design.
Figure 8 inverted delay drive circuit
The chip is an output high-voltage gate driver, with a 14-pin dual in-line. The drive signal delay is ns level, and the switching frequency is from tens of hertz to hundreds of kilohertz. The IR2110 has two input signals and two output signals. One of the two output signals has a level shifting function that directly drives the power devices on the high-voltage side. The driver can be run in common with the main circuit, and only need to control the power all the way to overcome the shortcomings that the conventional driver needs multiple isolated power supplies, greatly simplifying the hardware design. IR2110 simple truth map as shown in Figure 9 below.
Figure 9 IR2110 simple truth map
IR2110 has two output drivers, the signal is taken from the input signal generator, the generator provides two outputs, the low side of the drive signal directly from the signal generator LO, and the high side of the drive signal HO must be through the level of conversion For high-side output driver. The system has driven double needs an IR2110 can be.
Due to driving the double tube, and the double tube can not be turned on at the same time, the control IC outputs have only one signal. In the control IC output and drive, an anti-phase delay circuit needs to be added. The PWM output by the control IC is in-phase and in-phase After the device, the resistor R29 and R30 pull-up capacitor C12, C13 were charged delay, making the two PWM symmetrical complementarity and has a certain dead zone, to ensure that the two main switch circuit will not turn on. The waveform of HIN and LIN in the circuit is shown in Figure 10 below.
Figure 10 inverted drive waveform
3.4 Main Circuit and Output Sampling
The main circuit is shown in Figure 11, the uses of a half-bridge switching circuit.
Figure 11 main circuit
According to the rectified voltage and input current parameters, the IRF840 is selected as the high-frequency switch. The maximum withstand voltage VDS is 500V and the maximum withstand current ID is 8A, which meets the design requirements. Freewheeling diodes working in the high-frequency state of the general select fast recovery diodes. Here I choose HFA25TB60, which can withstand 600V reverse voltage drop, the maximum on-current 25A, and the recovery time is only 35ns. The output part of the two The resistor divides the voltage sampling circuit, as shown in Figure 12 below.
Figure 12 Voltage Sampling Circuit
3.5 Over-current Protection Circuit
Overcurrent protection circuit as shown in Figure 13 below.
Figure 13 overcurrent detection circuit
In the upper end of the main circuit in series with a 0.33-ohm 10W power resistor as a sampling resistor, when the current is too large, the optocoupler phototransistor conduction, the detection circuit outputs a high level to IR2110 SD terminal, SD is low because the effective, High off point, so the current is too large to protect the circuit. And as mentioned earlier, IR2110 itself has a variety of protection circuits, so the external current and voltage protection circuit can be greatly simplified.
Ⅳ Conclusion
This design gives a non-isolated topology design of the high-power switching power supply method, the circuit structure is simple. In the main circuit, the half-bridge circuit is used instead of the traditional single-tube switch circuit. When the upper tube is closed, the opening of the lower tube can better ensure the stability of the output freewheeling and ensure the output of the power.
The article does not give the calculation method of inductance, because it is not the focus of discussion, according to the circuit output current, voltage and switching tube RDS (MOSFET tube drain and source resistance) and other parameters to calculate the actual should stay Have some margin value. System operation is basically stable, which can be considered for industrial power supply design.
Ⅴ FAQ
1. What is an adjustable power supply?
Adjustable power supplies allow the output voltage or current to be programmed by mechanical controls (e.g., knobs on the power supply front panel), or by means of control input or both. An adjustable regulated power supply is one that is both adjustable and regulated.
2. What does a switching power supply do?
Switching power supplies are designed for high efficiency and small size. They incorporate a switching regulator to convert electrical power efficiently. Switching DC power supplies regulate the output voltage through a process called pulse width modulation (PWM).
3. What do you mean by SMPS?
A switched-mode power supply (switching-mode power supply, switch-mode power supply, switched power supply, SMPS, or switcher) is an electronic power supply that incorporates a switching regulator to convert electrical power efficiently.
4. When should you use a switching power supply?
The switching power supply implies higher efficiency due to the high switching frequency, enabling it to use a smaller, less-costly high-frequency transformer as well as lighter, less-costly filter components. Switching power supplies contain more overall components, therefore are usually more expensive.
5. What are the 4 stages of the power supply?
Most power supplies are made up of four basic sections: a TRANSFORMER, a RECTIFIER, a FILTER, and a REGULATOR.
6. What is the importance of power supply?
The purpose of a mains power supply is to convert the power delivered to its input by the sinusoidally alternating mains electricity supply into the power available at its output in the form of a smooth and constant direct voltage.
7. Which is a better linear or switching power supply?
Switching power supplies feature higher efficiencies, lighter weight, longer hold-up times, and the ability to handle wider input voltage ranges. Linear power supplies are usually less expensive, but are limited in capability and tend to be larger in physical size.
8. What is inside the power supply?
A rectifier that converts AC (alternating current) into DC. A filter that smooths out the DC (direct current) coming from a rectifier. ... A voltage regulator that controls the DC output, allowing the correct amount of power, volts or watts, to be supplied to the computer hardware.
9. What is the main function of SMPS?
A switched-mode power supply (SMPS) can be understood as an electronic circuit converting power with switching devices that turn on and off at high frequencies. They are also storage component like inductors or capacitors that supplies power when the switching as at its non-conduction state.
10. Can I use a power supply with higher voltage?
Voltage too high – If the adapter has a higher voltage, but the current is the same, then the device will likely shut itself off when it detects an overvoltage. ... The device could power on and just draw more current from the adapter than it's designed for. This could cause the adapter to overheat or fail.
Book Recommendation
Extensively revised throughout, Switching Power Supply Design & Optimization, Second Edition, explains how to design reliable, high-performance switching power supplies for today's cutting-edge electronics. The book covers modern topologies and converters and features new information on designing or selecting bandgap references, transformer design using detailed new design charts for proximity effects, Buck efficiency loss teardown diagrams, active reset techniques, topology morphology, and a meticulous AC-DC front-end design procedure. This updated resource contains design charts and numerical examples for comprehensive feedback loop design, including TL431, plus the world’s first top-down simplified design methodology for wide-input resonant (LLC) converters. A step-by-step comparative design procedure for Forward and Flyback converters is also included in this practical guide.
--Sanjaya Maniktala (Author)
Recognized worldwide as the definitive guide to power supply design for over 25 years, Switching Power Supply Design has been updated to cover the latest innovations in technology, materials, and components. This Third Edition presents the basic principles of the most commonly used topologies, providing you with the essential information required to design cutting-edge power supplies. Using a tutorial, how-and-why approach, this expert resource is filled with design examples, equations, and charts.
Get Everything You Need to Design a Complete Switching Power Supply: Fundamental Switching Regulators * Push-Pull and Forward Converter Topologies * Half- and Full-Bridge Converter Topologies * Flyback Converter Topologies * Current-Mode and Current-Fed Topologies * Miscellaneous Topologies * Transformer and Magnetics Design * High-Frequency Choke Design * Optimum Drive Conditions for Bipolar Power Transistors, MOSFETs, Power Transistors, and IGBTs * Drive Circuits for Magnetic Amplifiers * Postregulators * Turn-on, Turn-off Switching Losses and Low Loss Snubbers * Feedback-Loop Stabilization * Resonant Converter Waveforms * Power Factor and Power Factor Correction * High-Frequency Power Sources for Fluorescent Lamps, and Low-Input-Voltage Regulators for Laptop Computers and Portable Equipment
--Abraham I. Pressman (Author), Keith Billings (Author), Taylor Morey (Author)
Simplified Design of Switching Power Supplies is an all-inclusive, one-stop guide to switching power-supply design. Step-by-step instructions and diagrams render this book essential for the student and the experimenter, as well as the design professional. Simplified Design of Switching Power Supplies concentrates on the use of IC regulators. All popular forms of switching supplies, including DC-DC converters, inverters, buck, boost, buck-boost, pulse frequency modulation, pulse width modulation, current-mode control and pulse skipping, are described in detail. The design examples may be put to immediate use or may be modified to meet a specific design goal. As an instructional text for those unfamiliar with switching supplies, or as a reference for those in need of a refresher, this unique book is essential for those involved in switching power-supply design.
-
Describes the operation of each circuit in detail
-
Examines a wide selection of external components that modify the IC package characteristics
-
Provides hands-on, essential information for designing a switching power supply
--John Lenk (Author)
Relevant information about "The Working Principle of High-Power Adjustable Switching Power Supply"
About the article "The Working Principle of High-Power Adjustable Switching Power Supply", If you have better ideas, don't hesitate to write your thoughts in the following comment area. You also can find more articles about electronic semiconductors through the Google search engines, or refer to the following related articles.
Best Sales of diode
Photo |
Part |
Company |
Description |
Pricing (USD) |
|
Alternative Models
Part |
Compare |
Manufacturers |
Category |
Description |
|
Ordering & Quality
Image |
Mfr. Part # |
Company |
Description |
Package |
PDF |
Qty |
Pricing (USD) |
|