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DC Power Profile

Issuing time:2015-07-16
SHENZHEN Branch Power Technology Co., Ltd.-DC Power Profile

DC power supply (DC power) has positive and negative two electrodes, the cathode potential and high negative potential is low, when the two electrodes and circuit connectivity, the enabling to maintain a constant potential difference between the circuit ends, so that the outer circuit formed from positive to negative current.

Difference alone can not maintain the water level of the steady flow of water, and by means of the water pump continues to deliver a low point uphill able to maintain a certain level difference formed by the steady flow of water. Similarly, the electrostatic field alone can not sustain the charge arising from the current steady, and by means of a DC power supply, you can use non-electrostatic interactions (referred to as "non-static electricity"), a positive charge by the negative potential at the lower After power is returned to the interior of the positive electrode at a higher potential, to maintain the potential difference between the two electrodes, thereby forming a steady current. Therefore, the DC power supply is an energy conversion device, which the other forms of energy into electric energy supply circuit to maintain the steady flow of current.

DC power non-static electricity is generated by the positive and negative point. When the DC power supply and the external circuit connected in the external power supply (external circuit), due to the pushing force of the electric field is formed from positive to negative current. In the internal power supply (internal circuits), the power of the non-static effect makes a current flow from the positive electrode and negative, so that the flow of electric charge to form a closed loop.

Characterization of the power supply itself is an important feature is a power of the force, which is equal to the unit being non-static power when electricity made positive charge from the negative move by the internal power supply. When the power to provide energy to the circuit, the supplied power P is equal to the electromotive force E and I both power supply current product, P = EI. Another feature is the amount of power its internal resistance (the resistance) R0, when the current through the power when I, the internal power supply of thermal power loss (ie generated by Joule heat per unit of time) is equal to R0I.

When the positive and negative poles power supply is not connected, the power in the off (open) state, then the potential difference between the electrodes in power magnitude that is equal to the power of force. In the off state, the non-energy and energy conversion does not occur. When the load resistor connected to the power poles to constitute a closed loop, through the internal power supply current flows from the negative positive, then, the power provided by the power equal to the power delivered to UI EI external circuit (U is the positive power supply and the potential difference between the anode) and the internal resistance losses in the thermal power R0I sum, EI = UI R0I. Then, when the power supply provides power to the load resistance, the potential difference between the two poles of power U = E-R0I.

When a larger force with another power supply to force smaller power supply, positive then positive, then negative negative (for example, by DC generator to charge the battery), the smaller the force inside the power supply current from it The positive flow negative, then the outside world to the power supply input power UI, which is equal to the power of the energy EI and internal resistance per unit time stored in the thermal power loss R0I sum, UI = EI R0I. Thus, when the external input power to the power supply, the external power supply voltage applied between both should be U = E R0I.

When the internal resistance of the power supply may be negligible, it can be considered in the power of the force is approximately equal to the magnitude of the potential difference between the poles or voltage supply.

In order to obtain a higher DC voltage, the DC power supply is often used in tandem, then the total force is the sum of the respective power of the force, but also for the total resistance of the respective resistors and power. Since the resistance increases, the current intensity is generally used only for a small circuit required. In order to obtain a larger current density, a DC power supply, etc. may be used in parallel force, then the total force is the force, the total resistance of a single power supply in each of the parallel resistance value.

Many types of DC power, DC power of different types, the different properties of the non-static electricity, the energy conversion process are also different. In the chemical battery (such as batteries, batteries, etc.), the non-static electricity is chemically dissolved and deposition process associated with the ions, when chemical battery discharge, chemical energy into electrical energy and Joule heat in the temperature difference between the power supply (such as metal thermoelectric Even semiconductor thermocouple), the non-proliferation of static electricity is the role of the temperature difference and the difference between the concentration of electrons associated, outside temperature difference power circuits provide power, heat energy is partially converted to electrical energy. In the DC generator, the non-electrostatic electromagnetic induction, DC generator power, mechanical energy into electrical energy and Joule heating. In the photovoltaic cell, a non-static electricity is photovoltaic effect role, battery-powered light, the light energy into electrical energy and Joule heating.

GZD, GZD (W) Thyristor frequency switching DC power supply system


Jiuzhou Electric PowerLeaderTM series of high-frequency switching DC power supply system for large power plants, hydropower plants, EHV substation, unmanned substation as a control, signal, protection, automatic reclosing operation, emergency lighting, DC pumps ,, various DC DC power supply sub-switch operating mechanism, control AC instrumentation and automation equipment of the secondary circuit of uninterruptible power supplies and other electrical devices.

PowerLeaderTM series of high-frequency switching DC power supply of single-line principle:

GZD (W) high-frequency switching DC power source is charged screens, feeders screen, battery and DC voltage converter four units. Charger screen consists of several power modules and computer monitoring system components, a single cabinet (screen) maximum configuration 160A, if the need for greater output current multi-rack (screen) in parallel. Feeder screen with a computer on-line insulation monitoring device, when a ground fault occurs fed a branch may show a ground leg number and grounding resistors. Optional battery screen computer battery inspection device, at any time to monitor the status of the battery. DC voltage transmitter frequency DC transmitter can be used, when the closing bus control line bus at 180-300V voltage fluctuation of the output voltage can be firmly stabilized at 220V.

The basic principle of the high-frequency switching DC power supply modules

PowerLeaderTM series of high-frequency switching DC power supply with a phase-shifted full-bridge pulse width modulated soft switching control technology, making the module efficiency is further improved harmonics decreases. Frequency switching DC power supply module 380VAC three-phase three-wire balanced input, no phase sequence requirements, no neutral current loss in AC input terminals, the use of advanced devices and EMI filter spike suppression circuits. High-frequency switching DC power source is a three-phase full-bridge rectifier circuit AC to DC, the passive power factor correction (PFC), and then by the DC / DC converter circuit and the resulting high-frequency DC is inverted into stable and controllable DC output. Frequency switching DC power supply pulse width modulation circuit (PWM) and soft switching resonant circuit according to changes in the network and load automatically adjust the pulse width of the high frequency switching and phase angle, so that the output voltage and current at any permits can keep stable. JZ-22010D series of power high-frequency switching power supply either stand-alone work is done all the basic functions, but also the parallel combination of work and has a good flow effect and dryer. Frequency switching DC power supply by connecting with the computer, can achieve "telemetry, remote, remote control, remote adjustment" four remote functions. Frequency switching DC power supply with perfect protection, and ensure the module or group of modules operate independently and computer monitoring system of security and stability. Frequency switching DC power supply module bus master samples from all flow control. In parallel operation, high-frequency switching DC power module group can automatically select a master module, the shunt collected current, voltage and other external parameters for processing, centralized control of each module's output voltage and current. Thus, even a small current, but also to get a better average flow effect.

First, the test preparation

1. Get a DC power-related knowledge through experiments

With the integrated DC power supply design, installation and commissioning requires Society:

(1) Choose a transformer, rectifier diodes, filter capacitor and voltage regulator to design integrated DC power supply;

(2) control the DC voltage circuit debugging and testing methods of the major technical indicators.

2. Design tasks

Design a waveform DC power supply to meet:

(1) when the input voltage is 220V ± 10%, the output voltage from 3-12V adjustable output current is greater than 1A;

(2) the output ripple voltage is less than 5mV, regulators coefficient of less than 5 × 10-3, the output resistance is less than 0.1 ohm.

3. Design requirements

(1) Power transformer only theoretical design;

(2) a reasonable choice of integrated voltage regulator;

(3) complete the entire circuit theory design, computer-aided analysis and simulation, installation and commissioning, to draw schematics, homemade printing plates;

(4) design report writing, debugging summary report and instruction manual.

Second, instruments and equipment

Auto voltage regulator, various tools dual trace oscilloscope, multimeter (analog or digital), AC millivoltmeter each one, and a homemade board

Several components.

Third, the theory and analysis

1, the basic principle of the DC power supply.

When the mains switch on the transformer via the input mains voltage into the design of voltage, into the pre-regulator circuit, a pre-regulator circuit is to be preliminary output voltage regulation, which aims to reduce power adjustment tube voltage drop between input and output, reduce power regulator power consumption, improve the efficiency of the DC power supply, power supply is generally pre-thyristor stepless phase-adjusted output relay switching transformer tap shift be regulated. After a pre-filter ① power supply and the resulting voltage ripple basically stable at a relatively small direct current through the control circuit for controlling the power adjustment voltage accuracy and performance give precise and rapid tube top pressure will be asked compliant I only get a DC voltage and then after filtering through filter ② desired output DC output voltage in order to get my desired or steady flow current value, we also need to value and current value of the output voltage is sampled to detect and later transferred to the control / protection circuit, control / protection circuit detects the value of output voltage and current values and valuable voltage / current setting circuit set by a comparative analysis of driving pre-regulator circuit and power regulator the DC power supply output voltage and current values can we set, but when the control / protection circuit detects the start when abnormal voltage or current value of the DC power supply protection circuit protection status.

2. Regulated current performance metrics and test methods

DC power supply technical indicators divided into two types: one is the performance index, including allowing the input voltage, output voltage, output current and output voltage adjustment range; the other is the quality indicators used to measure the stability of the output DC voltage, including regulation factor (or voltage regulation), the output resistance (or current regulation), ripple voltage (peripheral and random drift) and temperature coefficient. Test circuit shown in Figure 3.

Figure 3 power supply performance test circuit

(1) The ripple voltage: AC voltage component is superimposed on the output voltage. With oscilloscope to observe its peak to peak is typically in the millivolt range. AC mV table can also be used to measure the RMS, but not a sine wave ripple, so there is some error, general DC power supply ripple voltage VP-P≤10mV.

(2) Regulator factors: the load current, ambient temperature is constant, the relative change in input voltage causes a relative change of the output voltage, namely:

(3) Voltage regulation: input voltage is ± 10% relative change in the output voltage when the relative variation, voltage regulators and voltage adjustment rate coefficient on the impact of the input voltage of the output voltage, so only one of them can be tested .

(4) the output resistance and current regulation

The same output resistance of the amplifier output resistance, whose value is constant when the input voltage, the output voltage and output current change in the ratio of the absolute value of the change in the current regulation: The output current is generated by varying the maximum value from 0 relative change in the output voltage value. Output resistance and current adjustment rate the impact of changes in load current on the output voltage, and therefore can only test one.

The basic technical specifications of the DC power supply

General DC input voltage: AC220V ± 10% 50Hz ± 5Hz, ripple and noise output: Cv≤1mvrms CC≤5mARms

4, choice points

1) 220V and 110V DC system should be used batteries. And below 48V DC system, using the battery pack, it can also be used by a 220V or 110V power supply battery power DC power converters (DC / DC converter).

2) The distance of the auxiliary power supply shop, when you need DC power, the DC system should be set up independently.

3) The batteries should run normally float charging.

4) Lead-acid batteries should not be set terminal of the battery; nickel-cadmium alkaline batteries are advised to reduce the number of terminals of the battery.

5) Nominal voltage DC system

(1) specifically for DC load control system should adopt 110V.

(2) DC system is designed for dynamic loads should adopt 220V.

(3) merger control loads and dynamic loads DC power supply system should adopt 220V.

6) Charging devices

(1) shall meet the battery charging and floating charge demand.

(2) should be long-term continuous duty.

(3) charging device should have a voltage regulator, steady flow and limiting performance.

(4) should have automatic and manual float charging, equalizing charge and steady flow, limiting the charging and other functions.

AC power supply (5) charging device is preferably a three-phase system input, rated frequency of 50Hz, rated voltage of 380 (1 ± 10%) V. AC input voltage small-capacity charging device can be single-phase 220 (1 ± l0%) V.

(6) l group battery charging device configured set of DC system, AC power charging device should be located two loops, running l circuit work, the other loop set aside. When operating a power failure, it should automatically switch to standby power.

7) Battery capacity selection criteria

(1) shall meet the discharge capacity of the whole plant (the) full blackout time of the accident;

(2) shall meet the initial accident (Imin) DC motor starting current and other shocks load current discharge capacity;

(3) shall continue to meet the battery discharge time random (5s) the impact of the load current discharge capacity;

(4) should be based on the most serious accidents discharge phase, calculate the DC bus voltage level.

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