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ENCYCLOPEDIA OF RADIO ELECTRONICS AND ELECTRICAL ENGINEERING 10-kilowatt switching power supply for a concert amplifier. Encyclopedia of radio electronics and electrical engineering
Encyclopedia of radio electronics and electrical engineering / Power Supplies The power consumed by amplifying installations in the sound systems of discos and small venues reaches 2...10 kW. At the same time, the output stages of the amplifiers require supply voltages from ±80 to ±160 V (and higher). This article proposes a bipolar switching power supply (SMPS) (Fig. 1), designed to power the final stages of a concert UMZCH. Among the power supply devices described on the pages of the magazine at the moment, this SMPS is the most powerful. The SMPS provides a constant bipolar output voltage, which is stabilized according to the pulse-width principle, and also has an overcurrent protection system (protection against overheating of components is not provided). SMPS is powered by a 3-phase network with a frequency of 50 Hz. The inclusion of a source in the network in the absence of an output load does not lead to an accident, but only negatively affects the voltage stabilization coefficient. But it must be emphasized that the normal launch of the SMPS is carried out only after the preliminary switching on of all other units and systems of the audio complex. The conversion frequency of the device is relatively low (25 kHz) and is due to the frequency properties of the powerful key transistors of the pulse converter. If there is no phase imbalance. the power factor of the SMPS can reach up to 0,955, which is due to the peculiarity of the operation of the Larionov rectifier with a zero diode and a filter with an inductive response.
Purpose of components The protection of the power supply in the event of any malfunction in the device is provided by a 3-phase circuit breaker FU1. Varistors RU1, RU6 block short-term surges that occur in the network. Inductors L2 ... L5 together with capacitors C7, C10, C11, C22, C28 C32, C34, C35, C37, C39, C44, C45, C221 ... C223 perform the function of a high-frequency reactive filter that suppresses ripple that could pass to the supply network. Resistors R45...R47 dampen chokes L3...L5, reducing their self-induction EMF. The filtered alternating mains voltage is connected to the Larionov VD35 rectifier with a VD36 zero diode. The ripple frequency at its output is 300 Hz. The inductor L11 with a small inductance is necessary to filter the high-frequency component that can enter the supply network, and also so that when capacitors C317, C346 C381 are connected to the output of the Larionov rectifier, the power factor practically does not decrease and the shape of the phase current is not distorted. Polypropylene capacitors C317, C346, C381 are necessary for the normal operation of the pulse converter. Fixed resistors R63 ... R66 discharge capacitors C317, C346.C381 after the device is completed. Thanks to the winding II of the two-winding inductor L11 and the diode VD38, the energy stored in the magnetic field of the inductor is recuperated back to the capacitors C317, C346, C381 of the converter power supply circuit. Varistors RU7 and RU8 suppress overvoltage impulses caused by the self-induction EMF of the inductor L11. If the 3-phase supply voltage is 380 V and there is no phase imbalance, then the phase voltages Uf are equal to
At the rated mains voltage at idle, the constant voltage at the output of the Larionov rectifier is
In reality, due to the fact that there are voltage drops on the diodes of the VD35 rectifier, the open thyristor VS1, the I winding of the L11 choke, etc., the DC voltage supplied to the pulse converter can be approximately 10% less. The charge of capacitors C317, C346 ... C381 at the moment the source is turned on generates a current pulse flowing through the Larionov bridge VD35. To ensure that the charge of the filter capacitors does not cause current overloads, a step-by-step start circuit is used, the actuating element of which is the thyristor VS1. At the moment the source is turned on, VS1 is closed, and the charge current C317, C346 ... C381 flows through the resistor R53, which limits it to 22,6 A (at maximum mains voltage). Such a current is not dangerous for VD35 diodes (the maximum current consumed by the pulse converter is approximately 24 A). After charging the filter capacitors, R53 is shunted by a thyristor VS1, which turns on with a delay determined by the C287-R57 circuit. Opens VS1 field effect transistor VT12, resistor R55 limits the current of the control electrode (resistance R55 is selected so that the current of the control electrode exceeds the unlocking current with a margin). Capacitor C286 prevents accidental switching on of the thyristor from interference. The circuit for limiting the current pulse generated by the charge of capacitors C317, C346 ... C381 is powered by a parametric stabilizer R54-VD37-VT11. Capacitor C288 suppresses voltage ripple. Fans M1 ... MZ are powered from the same stabilizer, the EMF of self-induction of the windings of which is suppressed by the VD39 diode. The stabilizer is connected to a switching rectifier with a smoothing LC filter on C228, C229, L6, VD27, VD30. Choke L6 - demodulating. It is necessary so that the voltage on the capacitors C228 and C229 is proportional to the effective, and not the amplitude value of the voltage on the winding II of the transformer T4. Polypropylene capacitor C229 with low parasitic resistance and inductance shunts electrolytic capacitor C228 at high frequency, preventing overheating of the latter. The primary winding of the linear transformer T2 is connected to the mains filter through the fuse FU2. and the secondary winding is connected to a VD24 bridge rectifier with a smoothing filter C36, C38. The rectified voltage is connected to the parametric stabilizer R34-VD13-VT9, the stabilized voltage from which is supplied to the U-shaped filter C14-C19-L1, C23, C27, C30. The SMPS master oscillator is built on a DA1 chip - a 2-stroke UC3825 controller manufactured by Texas Instruments (Unitrode) with strapping circuits. "The maximum current of each of the key transistors of the indicated IC is 2 A with a pulse duration of 0,5 μs (0,5 A at constant The purpose of the UC3825 IC pins in a DIP-16 plastic case (Fig. 2) is as follows: 1 - inverting input of the error amplifier,
On resistors R2, R10, R52, R58 (Fig. 1), an output voltage divider of the SMPS is organized, which is applied to capacitors C230 ... C257, C258 ... C285. Elements C5 and R11 increase the noise immunity of the automatic control system. A constant voltage drop across resistors R2 and R10 is connected to the inverting input of the error amplifier of the DA1 chip. According to the manufacturer's reference data, this voltage should be in the range of -0,3 ... + 7 V relative to pin 10 of the microcircuit. If a constant voltage of 2 V is supplied to the divider R10-R52-R58-R200, then by adjusting the resistance R10 it is possible to achieve voltage at pin 1 of DA1 in the range of +0,27 ... +5,3 V (with respect to the potential of pins 10 and 12 ). It should be noted that adjusting R10 will change the output voltage and, consequently, the voltage at the inverting input of the error signal amplifier. The output voltage stabilization system works like this. If the output voltage of the SMPS increases for any reason, then the voltage from the divider to pin 1 of DA1 also increases. This causes a decrease in the duty cycle of the pulses generated by the microcircuit entering the power modules, i.e. a decrease in the duration of bipolar pulses at a constant generation frequency. The effective voltage on the secondary windings of the pulse transformer T4 is reduced, and the DC voltage after the demodulating inductor L7, applied to the capacitors C230 ... C285, returns to its original level. DC voltage control is carried out precisely at the input of the power high-frequency filter, and not at its output, since the presence of an excessive phase shift would lead to instability of the automatic output voltage control system (instead of negative feedback, positive feedback and self-excitation of the SMPS could occur). It is extremely important that the capacitors C230 ... C243 and C258 ... C271 have the minimum values of parasitic resistance and inductance. The R9-C8 chain is a corrective error signal amplifier. The reference voltage (+5,1 V) is applied directly to the non-inverting input 2 of the error amplifier. Ceramic capacitor C2 filters the ripples. The ratings R1, R4 and C1 set the frequency of the pulses that DA1 generates. Capacitance C1 determines the duration of the pause ("dead time") between pulses of different polarities, The larger the capacitance C1, the longer the dead time. On components C6, R3, VT1, a "soft" start circuit of the master oscillator DA1 is assembled. Elements R12, C12, C13 - a passive filter that suppresses high-frequency ripples and "separates" low-current preliminary circuits and high-current final stage DA1. Capacitors C12 and C13 should have as little parasitic resistance and inductance as possible. Capacitor C13 - ceramic. The rated voltage of the tantalum capacitor C12 must not be lower than 50 V, otherwise it may break through, and tantalum capacitors usually fail with the circuit closed. Between the output stage of the DA1 microcircuit and the circuits for forcing the discharge of the gate-emitter capacitances of the key transistors of the power modules VT2 and VT10, there is a driver with two MOSFETs VT5 and VT6. Their purpose is to increase the power of the pulses supplied to the winding I of the matching transformer T1. Resistors R16 and R17 delay the opening and closing of transistors VT5 and VT6, and R18 and R19 discharge their gate-source capacitances, RC circuits C20-R22 and C21-R23 are necessary for damping the primary half-windings of the T1 pulse transformer. Without them, the shape of the control pulses for the key transistors of the VT2 and VT10 modules would be greatly distorted, which would inevitably lead to an emergency. The strength of the current flowing through the primary winding I of a power pulse transformer. T4, monitors the current transformer TK. Current pulses, flowing through resistors R39, R40, R43 and R44, create voltage drops on them, the magnitude of which is proportional to the current of the primary winding. The rate of voltage rise across these resistors is reduced by RC circuits C40-R37 and C41-R38, which, in addition, contribute to the rapid damping of parasitic oscillatory processes. Bidirectional transils (transil - Transient Voltage Suppression Diode) VD20 and VD21 limit the amplitude of overvoltage pulses. The pulses rectify Schottky diodes VD16 and VD17, loaded on C3 and R33, forming a peak detector. The rectified voltage is supplied to the voltage divider R27-R32. By rotating the slider of the tuned resistor R27, the required sensitivity is adjusted, which the current protection system should have. From the voltage divider, the overload signal is fed to the multi-link filter C9-C29-C31-R15-R26, which suppresses high-frequency ripples. The larger the capacitance C9, C29, C31 and the higher the resistance R15 and R26, the greater the inertia of the current protection system. If it is excessively inertial, it will not be able to perform protective functions, and if it is too fast, false positives are possible. The filtered overload signal voltage is fed to input 9 of the DA1 microcircuit, which, in the event of an emergency increase in current, will block the controller. While the voltage at pin 9 of DA1 is +0,9...+1,1 V with respect to pin 10, the pulse duty cycle decreases, and if this voltage reaches +1,25...+1,55 B, pulse generation stops. The typical turn-off delay time on pin 9 of the IC UC1825, UC2825 and UC3825 is only 50 ns, and the maximum delay time does not exceed 80 ns. According to the reference book, the maximum voltage that can be applied to input 9 relative to pin 10 is +6 V, and in this device it does not exceed 3,8 V. Matching transformer T1, current transformer T3 and power pulse transformer T4 provide galvanic isolation of input and output circuits of the device. Transformer T1 takes on the functions of galvanic isolation of circuits for forced discharge of gate capacitances of IGBT modules VT2 and VT10 from each other and from the transistor driver. Forced locking circuits of IGBT modules VT2 and VT10 are represented by four groups of components: R13, R20, R24, VD5, VD7, VD9, VT3; R14, R21, R25, VD6, VD8, VD10, VT4; R28, R30, R35, VD11, VD14, VD18, VT7; as well as R29, R31, R36, VD12, VD15, VD19, VT8. Resistors R20, R21, R30 and R31 are needed to slow down the switching on and off of the corresponding transistors in the power modules VT2 and VT10, to reduce the amplitude and duration of oscillatory processes. Without this, there would be a danger of loss of controllability of IGBT modules due to "snapping" of parasitic thyristor structures, caused by an excessively high signal slew rate. Experts from Powerex, Inc., which manufactures CM300DU-24NFH power modules, recommend gate resistor values in the 1...10 ohm range. Resistors R24, R25, R28 and R29 dampen parasitic oscillations that occur in the circuits. If we remove the loads of the windings II, III, IV and V of the matching transformer T1 and resistors R24, R25, R28 and R29, the shape of the voltage pulses on the secondary windings of this transformer takes the form shown in Fig. 3 (sweep duration - 5 μs / div.) . Getting pulses with such damped oscillatory processes should be avoided.
When the power supply is turned on, the power supply voltage of the converter is applied to parasitic voltage dividers formed from the gate-emitter and gate-collector capacitances of the IGBT modules. If you do not limit the voltage between the gates and emitters at a level safe for transistors, they will break through. The gate-emitter voltage of the CM300DU-24NFH IGBT modules must not exceed ±20 V, which is a normal value for this class of devices. The gate-emitter circuits are protected by bidirectional clamping diodes VD5, VD6, VD18 and VD19. The accelerated discharge of capacitances of the gate-emitter of IGBT modules is provided by bipolar pn-p transistors VT3, VT4, VT7 and VT8, which, when opened, bypass the control inputs of electronic switches. Resistors R13, R14, R35, R36 also help discharge the gate-emitter capacitances. Powerful limiting diodes VD3, VD4, VD22 and VD23 protect key transistors from overvoltages. Damping chains C3-R7-VD1; C4-R8-VD2; C42-R41-VD25; C43-R42-VD26 are snubbers. If they were absent, then every time when the keys were locked in the IGBT crystals, the power modules VT2 and VT10 would briefly release a large power, calculated in many kilowatts, and this would cause intense degradation of the semiconductors of the power transistors and, in the end, would lead to their output. out of service. Capacitors C46.C220 prevent long-term DC bias of the pulse transformer core. T4, which could cause saturation of the T4 magnetic circuit. On powerful diodes VD31. VD34, shunted with snubbers C224-R48, C225-R49, C226-R50 and C227-R51, two separate output pulse rectifiers are assembled. Inductor L7 is used for demodulation and group voltage stabilization. Capacitors C230 ... C285, C289 ... C316, C318 ... C345 and chokes L8 ... L10 form the output. U-shaped filter that smooths out high-frequency ripples. Capacitors C230.C243, C258 ... C271, C289.C316 must have minimal parasitic resistance and inductance. Resistors R60 and R61 discharge the output filter capacitors after the SMPS is finished. The HL1 LED indicates the on state of the device, and the resistors R59 and R62 limit the current flowing through it. Fuses FU3 and FU4 disconnect the load from the SMPS output filter capacitors in case of overcurrent. Possible component replacements Chip 0A1 brand UC3825 can be changed to UC2825, UC1825 or K1156EU2. The frequency-setting capacitor C1 must have a MPO temperature stability group. For example, a brand capacitor is suitable. K71-7. Do not use capacitors that may have "capacitance flicker". Capacitors C3, C4, C42 and C43 in damping circuits with a capacity of 15 nF and a rated voltage of 4 kV (at direct current) are used with a polypropylene dielectric brand Snubber FKP15N/4000 from WIMA. They can be exchanged for Snubber FKP15N/3000 devices. Capacitors C7, C10, C11, C34, C35, C37 are ceramic, Yl-type, and C22, C28, C32, C39, C44, C45, C221 ... C223 are polypropylene, metallized, X1-type. Capacitors C7, C10, C11, C34, C35, C37 can be used with DECE33J222ZC4B brands, and can be replaced with similar brands DHRB34C102M2FB or K15-5 with a capacity of 2.2 nF and a rated voltage of 6,3 kV. Capacitors C22, C28, C32, C39, C44, C45, C221 ... C223 - MKP10N330K1K0-27 from WIMA with a self-extinguishing case. These capacitors are replaceable with MKP10470N/2K, MKP10 1U/1.6K or similar. You can use metallized polypropylene capacitors of 0,33uF, 0,47uF or 0,68uF series. MKR1840 by Vishay, rated for 600 V AC. Capacitors C46.C220 with a capacity of 47 nF each and a rated DC voltage of 2 kV are high-frequency polypropylene, FKP14 7N / 2000. The total capacitance of a group of 175 capacitors connected in parallel is approximately 8,2 microfarads. Capacitors C230, C243, C258, C271, C289 ... C316 - high-frequency polypropylene grades FKP4 0.1U / 630 or MKR10 0.1U / 630. These capacitors must have minimal parasitic inductance and resistance. Capacitor C317 with metallized polypropylene dielectric - DC-LINK HC V255-type. Instead of a 340 uF capacitor, you can take a 346 uF capacitor of the same type and rated voltage. Capacitors C381 ... C147 - high-frequency polypropylene, FKP2000N / XNUMX. Capacitors C244, C257, C272, C285, C318, C345 - NQ series f. Aihuan Technology Group. The capacitor of this series with a capacity of 1600 uF and a rated voltage of 450 V can withstand a ripple current of 9,8 A at a frequency of 300 Hz and a temperature of 85 ° C. To ensure that the amplitude of the ripples on them does not exceed the maximum allowable value, it was necessary to combine the capacitors connected in parallel into groups. Trimmer resistors R1, R10, R27 of the brand SP5-2V can be changed to resistors SPZ-19A, SPZ-39, SP5-5V, SP16-5 or SP22-3. It is possible to replace it with resistors of the PVZ4A or PVMXNUMX series from Murata Manufacturing. However, imported trimmers have a different range of resistances, and, therefore, when replacing, it will be necessary to correct the resistance of the fixed resistors connected in series with the trimmers. Resistors R7, R8, R41, R42 - RA6 (non-inductive) of the company "LAET" in the case. TO-247. To cool the resistors, separate HS104-50 radiators with dimensions of 100x102x24,5 mm are used. Resistors R48, R51 can be used either of the same RA6 brand, or you can take 20 W SMHP series resistors in the TO-263 package from TT electronics, or make up 4 5 W non-inductive resistors. Fixed resistor R53 - wire, C5-43V-50 or C5-35V. It is important that this resistor can easily withstand short-term current overloads. Resistors R63, R66 - wire, C5-47V. Variators RU1...RU6 type S20K680 can be taken of the brands B72220-S 681-K101, TVR20112 or CNR20D112. The RU7B72220-S102-K101 varistor operates at 895 VDC and can absorb up to 410 J. It can be exchanged for two B72220-S681-K101 varistors connected in parallel (each operates at 895 V and can absorb up to 250 J) . Varistor RU8 TVR20241 has a voltage of 200 V DC and is capable of absorbing the highest energy of 108 J. The specified varistor is replaceable by B72220-S2131-K101, JVR-20N241K, S20K130E2 or S20K150. Diodes VD1, VD2, VD25, VD26, VD36 and VD38 brand DSDI60-16A can be changed to diodes DSDI60-18A of the same manufacturer or RHRG75120, RHRU100120 f. Fairchild Semiconductor Corporation". Diodes are mounted on separate coolers HS143-100 or similar. Bidirectional clamping diodes VD3. VD4, VD22 and VD23 (ONS261-10-9) can be replaced with. ONS261-Yu-8 or. ONS261-10-10. Suitable coolers are 0171 or 0371. Bidirectional limiting diodes VD5, VD6, VD18 and VD19 brand 1.5KE18CA can be changed to 5KR15CA or. P6KE18CA. Schottky diodes VD7...VD12, VD14, VD15 (SB5100) are replaced by MBR750. SB560, SB860 or SB860F. The zener diode VD13 1N5354B has a breakdown voltage of 17 V. It can be changed to 1SMA5930B, 1N5355B-MBR or 1N5353B. Schottky diodes VD16 and VD17 (1N5819) are changed to 11DQ06, 11DQ10, MBR160, SB140...SB160. SB1100, SR1100, SR106 or SR180. Bidirectional diodes VD20 and VD21 (1.5KE8.2CA) are replaceable with protective diodes R6KE8.2CA, R6KE10CA or 1.5KE10CA. Diode assembly VD24 type MB154W can be changed to one of the devices BR154, BR156, BR158 or MB156W. It is mounted on a cooler, for example, brand HS183 with dimensions 30x50x17 mm manufactured by "Kinsten Industrial". Ultrafast diodes VD27...VD30 HFA15PB60 can be replaced by DSEI12-06A. FES16DT. FES16FT or HFA15TB60. They are mounted on four separate coolers HS184-30 with overall dimensions of 30x41x30 mm or similar. Ultra-fast diodes VD31.VD34 150EBU04 allow a forward current of 150 A (at a temperature of 104 ° C) and withstand the highest reverse voltage of 400 V. Their typical reverse recovery time is 172 ns (at a forward current of 150 A, a reverse voltage of 200 V and a temperature of 125 °C). The maximum forward voltage drop across the 150EBU04 diode is 1.17V at 150A and 125°C. These components can be exchanged for HFA320NJ40C or HFA280NJ60C assemblies, consisting of two diodes. However, it should be remembered that the diodes in them have a common cathode. A replacement for the MUR20060CT is also acceptable. All four diodes (VD31...VD34) are mounted on independent coolers HS153-100 f. "Kinsten Industrial" or similar. Three-phase diode bridge VD35 brand RM75TC-2H can be changed to a similar bridge 160MT160KV. The diode bridge is installed on the cooler HS153-50 or similar. Zener diode VD37 brand 1N5350B has a breakdown voltage of 13 V (± 5%). It can be replaced with one of the 1N5351V, BZX85C-13V, or ZY13 zener diodes. Diode VD39 brand MUR420 can be replaced by BYD1100, BYV28-100. SBYV28-200. SF22. SF54 or SB5100. It is desirable that the HL1 LED has a green or blue glow. Instead of the L-7113CGCK brand LED, you can take one of the KIPM01V-1L, KIPM07G-1L, L-383SGWT, ARL2-5213PGC or L-1503SGC devices. The low-power pn-p transistor KT361G (VT1) can be exchanged for other transistors of the KT361 series, as well as for similar devices. VS 157, VS 158 VS250V, VS250S. Power modules VT2 and VT10 each contain two powerful IGBTs connected in a half-bridge circuit with integrated opposed diodes. The transistors of the CM300DU-24NFH modules allow operation at a frequency of up to 30 kHz in hard switching and at a frequency of 60...70 kHz in a resonant mode. The direct current of the transistor collectors is up to 300 A, the pulsed current is 600 A, and the maximum collector-emitter voltage is 1200 V (at a temperature of 25°C). The maximum collector-emitter saturation voltage of the transistors of the modules is 6,5 V, and its typical value is 5 V. Each power module must be installed on a separate cooler, for example, "DAU" of the IHV or IHM series, and a length of 300 mm is sufficient. Instead of these components, it is permissible to use CM200DU-24NFH modules or a number of discrete transistors, for example, IRGPS60B120KDP. The latter have a direct collector current of 105 A, a pulse current of 240 A, and a maximum collector-emitter voltage of 1200 V (at a temperature of 25°C). The device uses those components that the author had. When choosing key transistors, it should be remembered that the allowable current of IGBT collectors greatly decreases with increasing conversion frequency and temperature. As the temperature rises, the allowable power dissipation of the transistors also decreases. The highest current of the primary winding of a power pulse transformer. T4 is approximately 24 A, which also needs to be taken into account. Transistors VT3, VT4, VT7 and VT8 (2SA1244) can be replaced with 2SB1202. MOSFETs VT5, VT6 and VT12 (IRF530N) can be changed to IRFU3910, IRF530, IRL530N or IRFI540G. Transistors VT5 and VT6 are mounted on miniature coolers KG-331 manufactured by Kingcooler, and transistor VT12 is mounted on a radiator HS115-50, HS113-50 'Kinsten Industrial' or similar in efficiency. The transistor is mounted on a cooler HS9-2 or similar.The bipolar transistor VT6284 brand 2N6283 can be changed to KT827A.It should be mounted on a cooler HS827-143 or similar. Thyristor VS1 brand T161-160-18 is mounted on cooler 0171 or 0371. It can be replaced with T161-160-14, T161-160-15, T161-160-16, T261-160-18 or T161-200-14. Choke L1 - LPV2023-501KL f. "Bournes". According to reference data, the inductance of its winding is 500 (±10%) µH, and its maximum resistance is 0,28 ohms. The inductor can withstand a maximum current of 1,5 A. The inductor L2 is performed on two toroidal magnetic cores made of atomized iron stacked together. T650-26 or T650-52, size K165,0x88,9x50,8 f. "Micrometals". The inductor windings are wound simultaneously in three wires. Each winding should contain 18 turns and have an inductance of 265 uH. As a winding wire, it is permissible to use a "pigtail" of 10 strands of copper wire PEV-2 or PETV 0,55 mm (for copper). Inductors L3 ... L5 are made on toroidal cores of atomized iron T400-26D, size K102x57.2x33 mm, with a "pigtail" of 10 strands of copper wire PEV-2 or PETV with a diameter of 0,55 mm each (for copper). Each winding consists of 32 turns, their inductance is 265 uH. Choke L6 taken LPV2023-501KL f. "Bournes". It has a maximum current of 1,5 A, a winding inductance of 500 (±10%) µH, and its resistance is no more than 0,28 ohms. Two-winding inductor L7 is performed on one toroidal magnetic core made of atomized iron. T650-26 or T650-52 K165x88,9x50,8 mm. The inductor windings are laid simultaneously in two wires until the inductance of each winding is 35 μH (the number of turns of each winding is 10). The windings are made with a "pigtail" of 90 strands of wire PEV-2, PETV or PELSHO 0,55 mm each (for copper). Due to the fact that the output rectifier is full-wave, the rectified voltage ripples have twice the frequency of the conversion frequency. Inductors L8...L10 are made on ring magnetic cores made of atomized iron. T650-26 or T650-52 K165x88,9x50,8 mm. The number of turns of each winding is 10, and the inductance of each inductor is 35 μH. A "pigtail" of 90 cores with a diameter of 0,62 mm each acts as a winding wire. The two-winding inductor L11 is implemented on two toroidal magnetic cores made of atomized iron stacked together. T650-26 or. T650-52, size K165x88,9x50.8 mm manufactured by Micrometals. The windings are wound with "pigtails" of 22 strands of wire of the PETV or PEV-2 brands 0,55 mm (for copper). Windings, each of which has 29 turns, are wound in two wires. The inductance of each winding is about 675 uH. The pulse transformer T1 is made on a toroidal magnetic circuit made of M2000NM-A ferrite, size K39x24x7. Winding I is wound with four-fold wires PEV-2 or PETV 0,38 mm, windings II, III, IV and V - double-folded wires of the same grades 0,38 mm. Winding I has 130 + 130 turns, windings II, III, IV and V - 130 turns each. Interwinding insulation is performed with a tape made of polyester or lavsan. The inductance of windings II, III, IV and V, as well as any of the primary half-windings, is 22 mH. The T1 transformer can also be wound on the B36 armored core made of M2000NM1 ferrite (without trimmer and gap). In this case, the windings II, III, IV and V and each of the primary half-windings must contain 88 turns of wire of the same grades and the same diameter. The inductance of the windings will also not change. Instead of a linear single-phase transformer T2 brand. OSM1 -0,063 380/5-24, you can take the transformer OSM 1-0,063 380/36, OSM 1-0,1 380/5-24, OSM 1-0,16 380/5-24 or similar. Current transformer. T3 is made on a magnetic circuit Ш 12x15 from manganese-zinc ferrite 2500NMS1-11 or 3000NMS. The primary winding consists of one turn, for convenience, made in a bundle of 22 strands of wire PEV-2 or PETV 0,55 mm (for copper). The diameter of each vein, taking into account the thickness of the insulating coating, is 0,62 mm. To increase the electrical strength of the insulation, the primary winding of the current transformer is passed through a fiberglass tube. The secondary winding contains 74 + 74 turns of two folded single-core wires of the same grades of 0,33 mm (for copper). To prevent saturation, a non-magnetic gap of 0,05 mm thick is left in the core. Power pulse transformer. T4 can be performed on five sets of magnetic cores folded together through insulating gaskets with a thickness of 0,05 mm. Ш20х28 from ferrite 2500НМС1, designed for operation in strong magnetic fields. With this configuration, most of the windings will be shielded from the ferrite surrounding the side cores. In the magnetic core, it is useful to make a non-magnetic gap of 0,02 + 0,02 mm, which will increase the maximum allowable magnetic field strength in the core. The use of large magnetic circuits is due to the conversion frequency of 25 kHz, the choice of which is associated with the permissible switching speed of the transistors of the VT2 and VT10 modules. The I T4 winding has 9 turns of "pigtail" of 18 strands of PEV-2 or PETV wire 0,47 mm. Winding II has 1 turn 0,47 mm. Windings III and IV should be as similar as possible and consist of 2 + 2 turns of "pigtail" of 38 strands of 0,4 mm each. Between the windings it is necessary to lay thin insulation (no more than 0,3 mm), but which must provide the necessary dielectric strength. It should be noted that it is very difficult to lay the windings, given that the magnetic circuit window turns out to be almost completely filled. At least 4 radiators of the KG-370 or KG-222 brand should be glued to the transformer core through insulating mica gaskets. The three-phase circuit breaker FU1 brand ABB S203 C40A can be changed to ABB S203R C32, Moeller 6P PL40-C3 / 3, Moeller 6P PL32-C3 / 3. Fuses FU4 and FU120, rated for a trip current of 2 A, can be used for automobiles from "FLOSSER", type "B" or brand. PN-XNUMX. Fans М1...МЗ JF0825B1Н manufactured by "Jamicon Corporation" with a supply voltage of 12 V and a current consumption of 0,19 A have dimensions of 80x80x25 mm and a capacity of 1,1 m3/min. They can be replaced by JF0815B1H. JF0825S1H,EC8025M12SA.KF0820B1H, KF0820S1H or similar, consuming current less than 0,2A. Design The power supply device is connected to the network with a flexible cable of the brand. KGET-6 3x10+1x6+1x6 (TU16.K09-125-2002) or similar. Capacitors C12, C13 must be located in close proximity to pins 12 and 13 of the DA1 microcontroller. The length of the conductors and the length of the tracks should be kept as short as possible. The board with the master oscillator is placed in an electromagnetic shield electrically connected to pins 10 and 12 of DA1. Capacitors C46.C220 are soldered close to each other on both sides of a long double-sided printed circuit board, resembling a ruler, along which only 4 bus tracks are etched: two on one side, and two on the opposite side. Capacitors C346 ... C381 are connected directly to the outputs of the key transistors of the VT2 and VT10 modules. Damping circuits C3-R7-VD1, C4-R8-VD2, C42-R41-VD25 and C43-R42-VD26 are connected directly to the collector-emitter terminals of the transistors of the VT2 and VT10 modules. Damping RC circuits C40-R37, C41-R38, C224-R48, C225-R49, C226-R50 and C227-R51 are located as close as possible to the respective components; current transformer T3 and diodes VD31 ... VD34. Parts mounted on coolers are installed with thermal grease of the brand, ALSBG-3, KPT-8 or similar. Power pulse transformer. T4 is located in the air flow path of one of the fans M1 ... MZ, since when the SMPS operates in a long-term mode with maximum output power, the transformer heats up quite significantly. The entire SMPS is shielded, the electromagnetic shield is connected to a common wire. Under the capacitor C8 and resistor R9, as well as the tracks connecting them on the opposite side of the double-sided board, it is advisable to leave an unetched foil that plays the role of a screen, which is connected to pins 10 and 12 of the DA1 chip. Setting and adjustment. Before tuning, you need to carefully check the installation and phasing of transformers T1, T4, chokes L2, L7 and L11, and then adjust the resistance of the tuning resistors. The resistance R27 should be maximum, and the sliders of the resistors R1 and R10 are set to the middle position. Now you can proceed to unit testing of the device, which will require an oscilloscope, a laboratory power supply, a multimeter, load equivalents (powerful resistors) and two 300 W incandescent lamps. First you need to make sure that the network filter is operational. During the test, remove the FU2 fuse to turn off the auxiliary power supply of the master generator, and do not connect the VD35 rectifier to the line filter. When the filter is connected to the network, an alternating three-phase voltage of exactly the same amplitude as at the input must be present at its output. In the absence of load, the reactive component of the current consumed by the filter from the network should not significantly exceed 0,4 A, and the active component of the current should tend to zero. Then the filter is disconnected from the network and the Larionov rectifier is connected to it. The rectifier on diodes VD27 ... VD30 is disconnected from the winding II of the pulse transformer. T4 and connect a laboratory power supply with an output voltage of 15 ... 20 V and a permissible current of at least 1 A to it. There should be a constant voltage of approximately 288 V on the capacitor C12, the M1 ... M1 fans should work and. finally, thyristor VSXNUMX should open. Now the laboratory power supply is turned off, but not disconnected from the rectifier. The circuit is broken between the connection point of the varistor RU8 of the L11 inductor, resistor R63, capacitors C317, C346, C381 and the connection point of the IGBT collectors VT2.1.VT10.1, resistors R7 ... R41. diodes VD1, VD3. VD22, VD25. Thus, the pulse converter will be disconnected from the mains rectifier with a system of stepwise charging of filter capacitors. In parallel with the capacitor C317, a load equivalent is connected - two incandescent lamps of the LON type with a power of 300 watts connected in series. During the experiment, when a noticeable heating of the resistor R53 begins, voltage is applied to the rectifier VD27.VD30 from the laboratory power supply. After completing all the preparatory operations, turn on the device in the network. A constant voltage of approximately 36 V should be present on the VD515 diode at the rated mains voltage (from 463 V to 565 V) with a mains voltage deviation of ± 10%). In this case, the thyristor VS1 must be closed, which can be determined both by instruments and by the presence of heating of the resistor R53 Turn on the laboratory power supply, and VS1 must open, which will cause a decrease in the temperature of the resistor R53. If so, then disconnect the device from the network, turn off the laboratory power supply and restore the connections between the capacitor C317 and the collectors of transistors VT2.1 and VT10.1, as well as the rectifier VD27 ... VD30 and winding II of the transformer T4. The removed fuse FU2 is returned to its place. The VD24 diode bridge is disconnected from the T2 transformer and connected to a laboratory power supply with an output voltage of 20 V (from 19 to 24 V). A constant voltage of approximately 19 V should be present on capacitors C30 and C15. An oscilloscope is connected to terminals 11 and 14 of the DA1 microcircuit and a frequency of 1 kHz is set using a tuned resistor R25. During the period, two bipolar pulses of a rectangular shape with steep fronts should be observed, and between the pulses there should be a protective pause (Fig. 4, sensitivity - 5 V / cell, sweep duration - 5 μs / division). The duration of the protective pause is chosen based on the parameters of the key transistors used. It is desirable that it be not less than 2,1 μs. To change the duration of the dead time, you need to take a capacitor C1 with a different capacitance.
A larger capacitance will increase the duration of the pause at the zero level, and a smaller one will vice versa. But adjusting the capacitance of capacitor C1 will lead to a change in the conversion frequency, and you will have to re-adjust the frequency with a tuning resistor R1. Between the drains of transistors VT5 and VT6 there should be voltage pulses of almost the same shape as in Fig. 4. The shape of the voltage pulses on both halves of the primary winding of the matching transformer T1 is shown in Fig. 5 (at the time of measurement, no loads are connected to the windings II, III, IV and V). To check the operability of the current protection circuit, the secondary winding of the current transformer T3 is soldered, and in parallel with the resistors R39 and R43, a laboratory power supply is connected with a voltage of 6 V so that its "+" is connected to the anode of the VD16 diode, and "-" - to the terminals 10 and 12 DA1. In this case, the controller must stop generating pulses. If you connect the "+" of the laboratory power supply to the anode of the VD17 diode, the generation of pulses should also stop. Disconnect the laboratory unit and solder the T3 winding in place. You can check the operation of circuits that accelerate the discharge of the capacitances of the gate-emitter transistors of the VT2 and VT10 modules (R13-R20-R24-VD5-VD7-VD9-VT3, R14-R21-R25-VD6-VD8-VD10-VT4, R28-R30-R35 -VD11-VD14-VD18-VT7 and R29-R31-R36-VD12-VD15-VD19-VT8 In the presence of these circuits, the discharge of the gate capacitances should occur faster than in their absence.It is useful to check the shape of the voltage pulses between the gate-emitter terminals of the key transistors of power modules VT2 and VT10. Without gate capacitance discharge circuits, the pulse shape is shown in the oscillogram in Fig. 6a, and in the presence of these circuits - in Fig. 66 (sensitivity - 2 V / cell, sweep - 0.2x50 μs / division). removed for one IGBT (the IGBT collector is not connected to the converter circuits, the other three IGBTs and the accelerated discharge circuits of their gate capacitances are disabled). The shape of the gate-emitter voltage pulses of the transistors of the power modules VT2 and VT10 is significantly influenced by the resistances of the damping resistors R24, R25, R28, R29 and the chains C20-R22 and C21-R23, which can be selected to improve the shape. To check the pulse-width voltage regulation, disconnect the resistor R58 from R52 and connect the "-" laboratory power supply to point d. In parallel with any of the secondary windings (II, III, IV or V) of the pulse transformer T1, an oscilloscope is connected, and the resistors R20, R21, R30, R31 are soldered for the duration of the experiment. By changing the output voltage of the laboratory power supply from zero to 100 V, they make sure that the duty cycle of the pulses changes, while their frequency and shape remain unchanged. This is shown on the oscillograms (amplifier sensitivity Y - 5 V / cell, sweep - 5 μs / division): Fig. 7a - minimum duty cycle, Fig. 76-average and Fig. 7c - maximum. If the duty cycle adjustment is successful, then turn off the laboratory power supply and solder the resistors R20, R21, R30 and R31 in place.
Only after the procedures have been carried out, it is possible to turn on the SMPS in the network (without connecting the load to it). With the help of a tuning resistor R10, the output voltage of the source is set to ± 100 V. Between the outputs of the SMPS -100 V and +100 V (after the fuses FU3 and FU4), a load equivalent with a resistance of 3.6 Ohm is connected. As a dummy load, Danotherm OHMEGA braking resistor modules or nichrome coils mounted on a non-combustible base can be used. By rotating the engine of the resistor R27, the protection system is activated and the SMPS is turned off at a load power of 11,1 kW. Then they take the equivalent load with a resistance of 4 ohms, which corresponds to an output power of 10 kW. When connected to the device, the protection system should not work. At the end of the tuning work, you should check the operation of the power source in a long-term mode and check the thermal conditions of the components. Attention! During the adjustment and during the operation of the source, it is necessary to follow the safety rules. Author: E.Moskatov, Taganrog, Rostov region.
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