KGPS-VII constant power thyristor intermediate frequency power supply control board is a new type of control trigger board developed by haanxi Gaoke power electronics Co., Ltd., and it is in the shape of the BSC8M-2 constant power thyristor intermediate frequency power supply control board The size, internal structure and working principle are exactly the same, so the introduction in the instructions for use is still drawn in the form of BSC8M-2 constant power thyristor intermediate frequency power supply control board. This control board is mainly composed of power supply, regulator, phase shift control, protection circuit, phase sequence adaptive circuit, start calculation circuit, inverter frequency tracking, inverter pulse formation, pulse amplification and pulse transformer. Its core components use high-performance, high-density, large-scale special ASIC-2 integrated circuits produced in the United States, combined with high-performance software developed by our company, to make an intelligent control chip---KC188, which enables the control of the board Except the regulator, the rest of the electric circuit is digitalized. The rectifier trigger part does not need any adjustment, and it has the characteristics of high reliability, high pulse symmetry, strong anti-interference ability, and fast response speed. It also has the characteristics of phase sequence adaptation The circuit does not need a synchronous transformer, so the phase sequence and synchronization work is eliminated in the on-site debugging. Only the gate wires of the three common anode thyristors need to be connected to the corresponding terminals of the control board, and the rectifier part can be put into operation .
inverter adopts sweep frequency zero-voltage soft-start mode, the starting performance is better than the ordinary zero-voltage soft-start circuit, and is equipped with an automatic repeat start circuit, which can prevent the occasional start failure of the intermediate frequency power supply. The startup success rate reaches 100%. The frequency tracking circuit adopts the average sampling scheme, which improves the anti-interference ability of the inverter, and only needs to sample the intermediate frequency voltage signal without the current signal of the tank capacitor, eliminating the need for an external intermediate frequency current transformer and determining the phase of the sampling current Troubles. Therefore, in the debugging and use field, there will be no problem that the intermediate frequency power supply cannot be started due to the phase connection of the intermediate frequency output line or the sampling current transformer.
The inverter angle adjustment circuit is also added to the inverter circuit, which can automatically adjust the matching of the load impedance to achieve constant power output, and can be made into a "fast melting" intermediate frequency power supply.
To achieve the purpose of saving time, saving electricity, and improving the power factor of the network side (this function can also be turned off). The main circuit of the inverter part is inside the KC188 large-scale integrated circuit, which is also a digital circuit.
BSC8M-2 control board has only 7 integrated circuits, 6 transistors, 6 trimmer potentiometers, and 32 lead terminals, making it easy to install. Suitable for all kinds of thyristor parallel resonance intermediate frequency power supplies.
BSC8M-2 control panel solicited opinions from many aspects in the design, and adopted effective measures to make debugging extremely convenient. Most of the parameter settings are automatically set inside the circuit, and only the parameter settings of 6 potentiometers need to be adjusted by the user, so it has strong versatility and interchangeability.
3. Applicable device
is suitable for various thyristor parallel resonance intermediate frequency power supplies of 400Hz゛8kHz.
4. Normal use conditions
4.1 The altitude does not exceed 2000 meters.
4.2 The ambient temperature is not lower than -10≧ and not higher than +40≧.
4.3 The maximum relative humidity of the air does not exceed 90% (at 20≧＼5≧)
4.4 There is no conductive and explosive dust at the operating location, no gas or vapor that corrodes metals and damages insulation.
4.5 No severe vibration and shock.
5. Main technical parameters
5.1 The rated voltage of the main circuit incoming line: 100V゛660V(50Hz) (note the matching of R3, R7, R11);
5.2 Control power supply: single-phase 17V/2A;
5.3 Intermediate frequency voltage feedback signal: AC 12V/15mA;
5.4 Current feedback signal: AC 12V/5mA three-phase input;
5.5 Phase shift range of rectifier trigger pulse: α=0゛130o;
5.6 Symmetry of rectification trigger pulse: less than 1o;
5.7 Rectified trigger pulse signal width: −600μs, double narrow, 60o interval;
5.8 Rectifier trigger pulse characteristics: trigger pulse peak voltage: −12V;
Trigger pulse peak current: −1A;
Trigger pulse leading edge steepness: −0.5A/μs;
5.9 Inverter frequency: 400Hz~8kHz;
5.10 Inverter trigger pulse signal width: 1‖(16〜inverter frequency);
5.11 Inverter trigger pulse characteristics: trigger pulse peak voltage: −22V;
Trigger pulse peak current: −3A;
Trigger pulse leading edge steepness: −2A/μs;
(The trigger pulse transformer for inverter is external);
5.12 Maximum size: 246〜180〜30mm;
5.13 Fault signal output: When the control board detects a fault signal, it outputs a set of contact signals. The contact capacity is AC: 5A/220V; DC: 10A/28V.
6. Terminals and parameters of the control board
The control board has 32 M3 wiring terminals, and the function table of each terminal is shown in Table 1.
8.1 W1(If) The maximum output current setting potentiometer, when there is current feedback, the maximum output current can be set, the clockwise direction is the smallest, and the maximum adjustment range is about twice.
8.2 W2(Vf) The maximum intermediate frequency output voltage setting potentiometer, when there is voltage feedback, the maximum intermediate frequency output voltage can be set, the clockwise direction is the smallest, and the maximum adjustment range is about 2 times.
8.3 W3(θmax) The maximum inverter lead angle setting potentiometer, clockwise to increase, the maximum adjustment range is about 40o ~ 60o.
8.4 W4(θmin) The minimum inverter lead angle setting potentiometer, clockwise to increase, the maximum adjustment range is about 20o to 40o.
8.5 W5(F) External frequency meter setting potentiometer, clockwise direction increases the reading, the maximum adjustment range is about 3 times.
8.6 W6(Fmax) The maximum externally excited inverter frequency setting potentiometer, clockwise to increase, the maximum adjustment range is about 2 times.
9. Installation and connection
The overall dimensions of the BSC8M-2 control board are shown in Figure 1. G1゛G6, K1゛K6 trigger pulse connection wires are connected with 0.7mm2RV wires. It is recommended to use wires of different colors to indicate polarity. The remaining connecting wires are connected with 0.5mm2RV wires.
If the installed intermediate frequency power supply does not require reset function, alarm function, and internal frequency meter, the terminals CON2-1, CON2-6, CON3-8, and CON3-9 can be used.
Figure 1 BSC8M-2 control board component layout drawing
10. Application examples
Figure 2 is the electrical schematic diagram of a KGPS-160kW intermediate frequency power supply, which can be used as a reference for the principle design of other devices. Since the control circuit has already designed the logic of starting and shutting down, there is no need to consider the power-on sequence of the main loop and the control loop.
Figure 2 The electrical schematic diagram of a KGPS-160kW intermediate frequency power supply
11.1 Tools to be prepared for debugging
For a 20MHz oscilloscope, if the power cord of the oscilloscope is a three-pin plug, be careful not to connect the ＾ground wire￣. The oscilloscope housing needs to be insulated from the ground. Only one trace probe should be used. The X and Y axes of the oscilloscope must be aligned. , The probe needs to be compensated under the test signal.
If there is no high-voltage oscilloscope probe, use resistors as a voltage divider to adapt to the measurement of voltages above 600V.
A resistive load ＋500Ω, −500W.
11.2 Commissioning of the rectifier part (W1)
For the safety of debugging, the inverter bridge should be disabled before debugging. For example: disconnect one end of the smoothing reactor, and then connect a resistive load ＋500Ω, −500W to the DC port of the rectifier bridge. Turn the If trimming potentiometer W1 on the circuit board clockwise to the highest end (when a short circuit occurs during the debugging process, it can provide overcurrent protection). Set the DIP-1 switch on the main control board to the ON position. Use an oscilloscope to be ready to measure the DC voltage waveform output by the rectifier bridge. Turn the "given" potentiometer on the panel counterclockwise to the minimum.
Send three-phase power supply (no phase sequence can be divided), check whether there is a lack of phase alarm indication, if there is, check whether the incoming fast fuse is damaged.
Turn the "given" potentiometer on the panel to a large clockwise, the DC voltage waveform should be almost fully released (α「0o), and all the 6 wave heads are in. If the intermediate frequency power supply is 380V input, the DC voltmeter should indicate about 530V at this time (if the intermediate frequency power supply is 660V input, the DC voltmeter should indicate about 900V at this time). Then turn the "given" potentiometer on the panel to the minimum counterclockwise, the DC voltage waveform is almost completely closed, and the α angle at this time is about 120＜. The output DC waveform should be continuous and smooth in the entire phase shift range.
If six rectifier wave heads cannot be found during debugging, check whether the serial numbers of the six rectifier thyristors are connected correctly, and whether the gate lines of the thyristors are connected reversely or short-circuited.
During this process of debugging, you should also check whether the "given" potentiometer on the panel is connected reversely. If the "given" potentiometer is connected reversely, the DC voltage is almost maximum. Only when the "given" potentiometer is turned clockwise to the end, the DC voltage will be There will be a decrease.
The inverter bridge is connected in the power failure state, the inverter trigger pulse is turned on, and the resistive load at the rectifier bridge port is removed. Turn the Vf trimming potentiometer W2 on the circuit board clockwise to the highest end (overvoltage protection can be provided when inverter overvoltage occurs during debugging). Turn the DIP-1 switch on the main control board to the ON position, and turn the "given" potentiometer on the panel counterclockwise to the minimum.
After powering on for a few seconds, slowly turn the "given" potentiometer on the panel clockwise to increase. At this time, the inverter bridge will appear in two working states: one is the inverter bridge oscillating, and the other is reverse. The change bridge is directly connected. What is needed at this time is the inverter bridge direct connection. If the inverter bridge is in the oscillating state, the phase of the intermediate frequency voltage transformer can be adjusted in the state of power failure, that is, the output line of the intermediate frequency voltage transformer 20V winding can be adjusted. It will vibrate. In the operation of slowly turning the "given" potentiometer on the large panel, pay close attention to the response of the ammeter. If the indication of the ammeter increases rapidly, you should quickly turn the "given" potentiometer down counterclockwise to indicate the current There is a problem with the sampling circuit and the system is in the current open loop state. Check whether the current transformer is connected correctly, especially whether the primary and secondary sides of the 5A:0.1A current transformer are connected reversely, and whether the 68Ω resistor on the 0.1A winding is connected. The normal performance is that as the "given" potentiometer slowly increases, the indication of the ammeter also increases. When the "given" potentiometer stops rotating, the indication of the ammeter can stably stop at a certain scale.
When there is a through phenomenon, turn the ＾given￣ potentiometer on the panel clockwise to make the indication of the ammeter close to about 50% of the rated value. Use an AC voltmeter to measure the voltage between the three terminals of CON2-3, CON2-4, and CON2-5. The three voltages should be roughly the same. If the difference is too large, it means that the terminal of the current transformer with the same name is wrong and must be corrected. , Otherwise it will affect the normal operation of the current regulator.
Continue to turn the "given" potentiometer on the panel clockwise to the end, the indication of the ammeter should be close to the rated value, and adjust the W1 current feedback trimming potentiometer on the main control board counterclockwise to make the DC ammeter indicate the rated output current. Setting of rated current.
In this way, the debugging of the rectifier bridge is basically completed, and the inverter bridge can be debugged.
It needs to be pointed out that when the DC resistance of the smoothing reactor is small, when the rated current is set in the straight-through state, the phenomenon of DC current oscillation will occur, which can be solved by adding a little resistance in the DC loop. In addition, the water cooling device must be cooled by water when it is debugged.
When the power supply of the debugging site cannot supply the rated current of the device, the setting of the rated current can be carried out when the site is running at full load. However, it is necessary to determine whether the current sampling circuit is working properly under the condition of small current.
11.3 Commissioning of the inverter part
11.3.1 Calibration frequency table (W5)
The DIP switches on the main control board are all set to the OFF position, and the "given" potentiometer on the panel is turned counterclockwise to the minimum. Connect the oscilloscope to the tube case of Q5 or Q6, measure the other excitation frequency of the inverter trigger pulse (the other excitation frequency can be adjusted by W6), adjust the W5 fine-tuning potentiometer to make the reading of the frequency meter consistent with that measured by the oscilloscope .
If the intermediate frequency power supply uses a special intermediate frequency frequency meter, this step of debugging can be omitted. However, it is recommended to use a frequency meter modified from a DC milliampere meter. On the one hand, the highest external excitation frequency can be measured. On the other hand, it is cheap.
11.3.2 Starting Vibration Inverter (W6)
First, check whether the gate line connection of the inverter thyristor is correct, and whether the brightness of the LED on the last stage of the inverter is normal. If it is not bright, it means that the E and C terminals of the last stage of the inverter are connected reversely. Then disconnect the external connection of CON3-5 on the main control board to see if the extinguished LED inverter stage is in the diagonal position of the inverter bridge.
Turn the DIP switches on the main control board to the OFF position, turn the "given" potentiometer on the panel counterclockwise to the end, and adjust the W6 trimming potentiometer on the control board to make the highest excitation frequency higher than the tank resonance frequency Rotate the W3 and W4 trimming potentiometers in the middle position. Turn the "given" potentiometer on the panel clockwise to slightly larger, then its excitation frequency starts to sweep from high to bottom (as can be seen from the frequency table), the inverter bridge enters the working state and starts to vibrate. If it does not vibrate, it is manifested by repeated frequency sweeping by the excitation signal, which can adjust the phase of the intermediate frequency voltage transformer, that is, reverse the output line of the 20V winding of the intermediate frequency voltage transformer.
If the output line of the 20V winding of the intermediate frequency voltage transformer is reversed, it still fails to start. At this time, check whether the resonance frequency of the tank circuit is correct. You can use a capacitance/inductance meter to measure the capacitance of the electric heating capacitor and the inductance of the inductor to calculate the resonant frequency of the tank circuit. When the resonant frequency of the tank circuit is in the range of 0.6 to 0.9 times the highest excitation frequency, Starting should be easy. Then check whether the inverter thyristor is damaged.
11.3.3 Setting the front angle of the inverter (W3, W4)
After the inverter starts to vibrate, you can set the front angle of the inverter, turn the DIP switches in the OFF position, observe the waveform of the voltage transformer 100V winding with an oscilloscope, and adjust the W4 trimmer potentiometer on the main control board to reverse the phase The lead angle is about 22o. At this time, the ratio of the intermediate frequency output voltage to the DC voltage is about 1.2 (if the commutation overlap angle is large, the inverse conversion phase lead angle can be appropriately increased). The minimum inverter lead angle is set in this step. It is generally hoped that it is as small as possible. Of course, a too small inverse conversion phase lead angle will cause the inverse conversion phase to fail, which is manifested as repeated starting when the intermediate frequency voltage rises.
Then turn the DIP-2 switch to the ON position, adjust the W3 trimming potentiometer on the main control board, and set the maximum reverse conversion phase lead angle. According to the requirements of different intermediate frequency output voltages, the maximum inverse conversion phase lead angle is also different. For example, when the three-phase input voltage of the intermediate frequency device is 380V and the rated intermediate frequency output voltage is 750V, the maximum reverse conversion phase lead angle is required to be around 42＜. At this time, the ratio of the intermediate frequency output voltage to the DC voltage is 1.5. It is generally hoped that it is as large as possible, which can still ensure that the intermediate frequency output voltage reaches the rated value when the input voltage of the system is low. When the input voltage of the system is high, due to the function of the voltage regulator, the intermediate frequency output will still not appear over-voltage.
This debugging work should be carried out at 50% of the rated intermediate frequency output voltage. Note that the 1.2 times relationship must be adjusted first, and then 1.5 times the relationship, otherwise the order will be reversed, and there will be problems with each other. Sometimes the voltmeter is inaccurate, which brings wrong conclusions to debugging, so the lead angle measured by the oscilloscope should prevail.
If the front angle of the inverter is too large during debugging, check whether the resonance frequency of the tank circuit is too low.
11.3.4 Setting of rated output voltage (W2)
Set the rated output voltage under light load conditions, turn the DIP switches on the main control board to the OFF position, turn the W2 trimming potentiometer clockwise to the maximum, and turn the ＾given￣ potentiometer on the panel clockwise to increase. The inverter bridge works. Continue to turn the "given" potentiometer on the panel clockwise to the maximum. At this time, the output intermediate frequency voltage is close to the rated value. Adjust the W2 fine-tuning potentiometer counterclockwise to make the output intermediate frequency voltage reach the rated value.
In this debugging, we can see this phenomenon: that is, after the DC voltage rises to the maximum value, the intermediate frequency output voltage can continue to rise with the "given" potentiometer's spin.
When setting the rated output voltage, it should be carried out under the condition that the DC current is lower than the rated current, otherwise the intermediate frequency output voltage cannot be adjusted due to the effect of current limiting.
So far, all 6 trimming potentiometers have been adjusted, and the debugging is over.
12. Matters needing attention
12.1 Please remove the control board when doing insulation and withstand voltage test of the thyristor device, otherwise it may cause permanent damage to the control board.
12.2 The internal circuit and parameters are subject to change without notice.
12.3 Our company is not responsible for any damage to parts other than the control board during use.
12.4 The KC198 device is a CMOS device, so care should be taken when using it. It is strictly forbidden to short circuit between the two pins of the device, otherwise the chip will be damaged. To ensure the safety of the device, do not use a multimeter to directly measure the pins of the device.
12.5 When the control board is connected to the main circuit, the area marked DANGER HIGH VOLTAGE on the control board will have high voltage. Please be careful to avoid electric shock.
13. Question discussion
13.1 Overvoltage protection
The overvoltage protection level has been fixed at 1.2 times the rated output voltage on the control circuit. When the rated voltage is set, the overvoltage protection should be set automatically. If 1.2 times is considered inappropriate, you can change the resistance value of R28 on the control board, increase R28, and the overvoltage protection level will increase; otherwise, decrease it.
13.2 Overcurrent protection
The over-current protection level has been fixed at 1.5 times the rated DC current on the control circuit. When the rated current is set, the over-current protection is automatically set. If 1.5 times is considered inappropriate, you can change the resistance value of R27 on the control board, increase R27, and the overcurrent protection level will increase; otherwise, decrease it.
13.3 Rated current setting
If the rated current is not set in step 12.2, when the system is running under heavy load, adjust the W1 current feedback trimming potentiometer on the control board counterclockwise to make the DC current expressed to the rated value. This is the same as the current setting of a general intermediate frequency power supply.
13.4 Separate excitation frequency
The excitation frequency must be higher than the maximum possible resonance frequency of the tank circuit, otherwise, the system cannot operate normally due to the "pulling" of the excitation frequency. It is appropriate that its excitation frequency is 1.2 times higher than the maximum possible resonance frequency of the tank circuit.
13.5 Constant power output
For smelting loads, constant power output is very important. To make the range of the constant power zone large, the range of the inverter lead angle from minimum to maximum must be as large as possible. At the same time, the matching of load impedance is also very important. important. Even if it is not a smelting load, doing so will help improve the power factor of the rectifier.
14. Service Commitment
14.1 Free maintenance within one year.
14.2 Provide free technical consultation.