• 专利附录
  • 专利说明
  • 权利要求
  • 类似技术
  • 同族专利
  • 引用文献
  • 法律状态
  • 优先权
    • 专利摘要:
    A frequency converter of the series-capacitor type is made substantially insensitive to changes in output load by providing the same with means for limiting the voltage across the transformer and load capacitor or capacitors thereof to a pre-determined value.
    公开号:SU1223850A3
    申请号:SU772480856
    申请日:1977-05-12
    公开日:1986-04-07
    发明作者:Бенгт Геран Хедберг Джон
    申请人:Термал Дайнемикс Корпорейшн (Фирма)；
    IPC主号:
    专利说明:

    The invention relates to electrical engineering, in particular, to converter technology, and can be used in converters with a large number of load changes, for example, during welding.
    The purpose of the invention is to minimize energy losses in the inverter.
    Fig. 1 is a connection diagram of an inverter comprising voltage limiting means; Fig. 2 is a connection diagram of a control loop for use with an inverter; FIGS. 3 and 4 show voltage curves — time and current — time resulting from the normal operation of the inverter and when operating with small loads, unless a means for limiting the voltage is provided; in fig. 5 - voltage curves - time and current - time, which is obtained when the inverter operates at low load, provided with voltage limiting means; on ф | ИГ.6 and 7 - modifications of the means of stress limiting; in FIG. 3, voltage curves — time and current — time resulting from operation of the converter at low load and provided with a voltage limiting means.
    An inverter (FIG. 1) is connected to a power source with three-phase alternating current. The input current is rectified by six elements of rectifier 1, the rectified output voltage at ° input terminals 2 and 3 is equalized by the buffer capacitor 4, and the converter has a low input impedance due to the proximity of elements 1-4. The switching elements of the inverter are thyristors 5 and 6, which are switched on alternately. The transformer 7 of the frequency converter has a primary winding 8 connected to load capacitors 9 and 10, and a secondary winding 11 connected to output pins 12 and 13 via an intermediate bridge 14 and a choke 15. Two load ends (hold the welding electrode and weld product) can be connected to pins 12 and 13. Between pins 12 and 13 a capacitor 16 is installed, which, when using an inverter as a source of welding current, can serve to maintain the required open circuit voltage


    Shunt 17 is provided for measuring the load current, the voltage taken from the shunt being used to control the frequency converter.
    In the control loop (Fig. 2), one end of the shunt 17 is grounded, and the other is connected to an amplifier 18, which amplifies the signal removed from the shunt from milliliters to volts. The amplifier 18 is connected via a resistor 19 of comparison with a current control device in the form of a potentiometer 20 with an amplifier 21, which is a level detector. The current control device 22 is designed to set the required current at the output of the inverter. Setting the required maximum output voltage of the inverter is provided by a voltage regulating device in the form of a potentiometer connected through a resistance 23 compared with the output 13 of the inverter and an amplifier 24 serving as a level detector.
    The control of the state of thyristors, 5 and 6 is provided by a sensitive circuit containing a transformer 25, the primary winding of which is connected via diodes 26 and 27 to the anodes (diodes) and cathodes (windings) of thyristors 5 and 6, respectively. One end of the secondary winding of the transformer 25 is grounded, the other is connected to a reference circuit connecting two resistors 28 and 29, and the resistor 29 is connected at one end to a source of a constant negative voltage. The common point of resistors 28 and 29 is connected to an amplifier 30, which serves as a level detector and whose trigger threshold is determined by resistors 28 and 29 and the voltage of the negative voltage source. Each of the amplifiers 21, 24 and 30 is connected to the corresponding output 31 - 33 of the valve 34. The element 35 operates in a lime-1 manner and can provide an output signal if the output signal from the amplifier 21; if from amplifiers 24 and 30 - positive, i.e. when the load current measured by shunt 17 is less than the value to which the regulating device 22 is installed (the load voltage at pin 13 is less than the value set on the regulating voltage device, and the anode voltage of one of the thyristors 5 or 6 is negative relative to its cathode, which in turn
    means that both thyristors 5 and 6 are closed).
    The output of the valve 34 is connected to the input of a monostable trigger 36, which has a predetermined pulse period corresponding to the recovery time of the thyristors 5 and 6, for example 30 µs. Thus, at the inverse output of flip-flop 36, a positive voltage pulse is received with a recovery time period of thyristors 5 and 6. The pulse is applied to the trigger input T of the flip-flop 37, as a result of which the flip-flop 37 changes the state at its outputs at the end of the pulse , from trigger 36. The direct and inverse outputs of trigger 37, respectively, are connected to the bases of transistors 38 and 39 via capacitors 40 and 41. The emitters of transistors 38 and 39 are grounded, and the collectors are connected to the primary windings of control transformers 42 and 43 x terminals of thyristors 5 and 6. The other ends of the primary windings of transformers 42 and 43 are connected to a source with a given positive potential. The signals from the outputs of flip-flop 37 are alternately fed to transistors 38 and 39, passing through capacitors 40 and 41 in a short period of time determined by capacitors 40 and 41, so that the thyristors 5 and 6 alternately receive a short switching pulse and alternately switching, created an alternating current, the frequency of which is determined by the input signals at the inputs 31-33 of the valve 34.
    Fig. 3 shows the voltages UA6 and U10, respectively, at the anode.
    the thyristor was the common point of the capacitors 9 and 10, as well as the voltage U8 on the primary winding 8 of the transformer 7 with the normal load at the output of the inverter. FIG. 3 also shows the output current I, s, the output currents Lg, (the latter is shown in dashed lines) of thyristors 5 and 6; t is the moment of time when thyristor 5 is open, tj is the moment of time when thyristor 5 is de-energized and the voltage between its anode and cathode arises due to the action of the resonant circuit - the primary winding 8 of the transformer 7 and capacitors 9 and 10; tj is the moment of time when the thyristor 6 is turned on; t ,, is the moment of time when thyristor 6 is de-energized and its anode becomes negative as a result
    ten
    15
    20
    25
    2238504
    the action of the resonant circuit 8-10, tj is the point in time when the thyristor 5 is again turned on, after which the cycle is repeated, ensuring that the load remains essentially unchanged.
    Fig. 4 shows the current and voltage curves when the inverter output current is small and / or the output voltage is high.
    Obviously, when the output current is small, it takes a long time to reload the load capacitors 9 and 10. This leads to the saturation of the transformer 7 and the occurrence of current overloads on it (shown by the peaks of the leading edges of the waveforms, representing the currents Ij, Ig). Such a pinching also causes a surge in the voltage of U 8, creating a high voltage UA6 on the capacitors.
    9 and 10, with the next subsequent impulse (tj), further release of transformer voltage increases even more, due to which an avalanche effect occurs for voltages UA6, U10, U8, leading to the destruction of the inverter element due to overvoltage. In order to avoid this, the inverter is supplied with a means of limiting the voltage between the primary winding of the transformer 7 and the load capacitors 9 and 10 to a predetermined value above the voltage on the input wires 2 and 3.
    The voltage limiting means (Fig. 1) contains two circuits that include, respectively, reference diodes 44 and 45, protective resistors 46 and 47 limiting currents, and diodes 48 and 49 blocking the current in the forward direction of the reference diodes. The locking voltage of the reference diodes 44 and 45 is chosen so that it is slightly lower than the highest voltage at which the voltage. U10 at the common point of capacitors 9 and
    10 can exceed the supply voltage at terminals 2 and 3.
    Thus, when the voltage 50 U10 exceeds the voltage at pin 2 or briefly drops below the voltage at pin 3 by an amount corresponding to the blocking voltage of the reference diodes 44 and 45, current can flow 55 along circuit 46, 44 and 48 to bus 2 and with opposite polarity at the common point of the capacitors 9 and 10 will flow along the contour 47, 45 and 49 from
    thirty
    35
    40
    45
    tires 3. The reference diodes 44 and 45 can be replaced by varistors 50 and 51.
    In another embodiment of the voltage limiting circuit (FIG. 1), resistors 46 and 47 are replaced with one resistor 52. The reference diodes 44 and 45 are interconnected, and the diodes 48 and 49 are installed in the same way as described. In addition (shown by dashed lines), the reference diodes 44 and 45 can be replaced by a single varistor 53. As shown by the dotted line 54 in FIGS. 1, 6 and 7, the voltage limiting circuits can, alternatively, be connected to the primary winding part 8 of the transformer 7
    When any of the protective circuits (Figures 1 and 6) are used, the voltage and current waveforms are obtained at low load, i.e. low output current and / or high output voltage at the output terminals of the frequency converter. Voltage U10 does not rise like an avalanche (figure 5), but is limited to one value that exceeds the voltage on bus 2 or 3 by an amount corresponding to the blocking voltage of the reference diodes 44 and 45, except for a relatively small and short voltage peak, which is created by the voltage drop on the corresponding protective resistor 46, 47 or 52. Thus, the current and voltage pulses do not change in time like an avalanche, as shown in Fig. 4.
    The voltage limiting means (Fig. 7) contains two circuits, each of which has a diode 48 or 49 and a thyristor 55 or 56. The circuits of the circuit also contain a common current limiting resistor 57. Each of the thyristors 55 I.PI 56 is connected to a trigger circuit, the content
    The current-limiting resistor 58 or 59 and the reference diode 60 or 61. The reference diodes 60 and 61 can be replaced with varistors.
    The locking voltage of the reference diodes is chosen so that it is somewhat lower than the maximum voltage that the voltage U10 at the common point of capacitors 9 and 10 can exceed the supply voltage on pins 2 and 3. Thus, when the voltage at this point exceeds the voltage on bus 2 or falls slightly below the voltage on bus 3 by a voltage of 1-1, corresponding to the blocking voltage of the reference diodes 60 and 61, the thyristor 55 or 56 is turned on, the current can flow from the specified point along the circuit 57, 55 and 48 to tire 2 and with opposite polarity at the common point of capacitors 9 and 10 can flow along the contour 57, 56 and 49 to iOMHe 13.
    When a protective circuit is used (Fig. 7), the voltage and current waveforms (Fig. 8) are obtained at low load, i.e. at a low output current and / or a high output voltage at the output terminals of the inverter. The voltage U10 at the common point of the capacitors 9 and 10 does not grow avalanche (Fig. 8), but is limited to the value that exceeds the voltage at the terminals 2 or 3 by an amount corresponding to the blocking voltage of the reference diodes 60 and 61, with the exception of a relatively small and short voltage peak, which is created due to a voltage drop across the common protective resistor 57. Thus, the current and voltage pulses do not change in time Oring, as shown in Figure 4,
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    FIG. five
    48
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    FIG. 6
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    Compiled by V. Avdeev Editor A. Shishkin Tehred and. Veres Proofreader V, But ha
    Order 1728/62 Circulation 631 Subscription
    VNIIPI USSR State Committee
    for inventions and discoveries 113035, Moscow, Zh-35, Raushsk nab., 4/5
    Branch PPP Patent, Uzhgorod, Proektna St., 4
    权利要求:
    Claims (5)
    [1]
    1. INVERTER containing two series-connected thyristors connected between input terminals, the common point of the thyristors connected to the first terminal of the primary winding of the load transformer, the second terminal of which is connected to the input terminals through the corresponding switching capacitor, characterized in that, in order to minimize energy loss, a circuit is introduced to limit the voltage, connected in parallel to the switching capacitor, while the circuit consists of a diode connected to the opposite source ku food, and restrictive element.
    [2]
    2. The inverter according to claim 1, characterized in that the limiting element is made in the form of a thyristor ', the control electrode of which is connected to its own anode through a threshold element.
    [3]
    3. Inverter pop 1, characterized in that the restrictive element is made in the form of a threshold element.
    [4]
    4. The inverter according to claims 2 and 3, characterized in that the threshold element is made in the form of a Zener diode.
    [5]
    5. The inverter according to claims 2 and 3, characterized in that the threshold element is made in the form of a varistor.
    ОЖбГ ns
    Fig /
    类似技术:
    公开号 | 公开日 | 专利标题
    SU1223850A3|1986-04-07|Inverter
    US4748532A|1988-05-31|Transformer coupled power switching circuit
    EP0084555B1|1986-12-30|High speed transistor switching circuit
    DE3122280A1|1982-04-22|Alternating-current switching device
    GB989325A|1965-04-14|Series connected controlled rectifiers
    US3448367A|1969-06-03|Inverter inhibit circuits
    US4866556A|1989-09-12|Circuit arrangement of a self protecting power switch
    US4203047A|1980-05-13|Gate circuit of gate turn-off thyristor
    US4119887A|1978-10-10|Starter for discharge lamp
    US3585403A|1971-06-15|Auxiliary turnoff circuit for a thyristor switch
    CA1302494C|1992-06-02|Active snubber structure and method for an electronicpower inverter
    US4464585A|1984-08-07|Gate circuit of gate turn-off thyristor
    US4155113A|1979-05-15|Protective circuit for transistorized inverter-rectifier apparatus
    US3588608A|1971-06-28|Circuit protection apparatus for disabling high voltage to a cathode-ray tube
    US4223236A|1980-09-16|Gate controlling apparatus for a thyristor valve
    DE2527106A1|1976-01-02|INDUCTION HEATER
    US3207994A|1965-09-21|Trigger-charging current interlock for pulse modulator
    US3281644A|1966-10-25|Inverter circuitry using controlled rectifiers
    CA1050170A|1979-03-06|Circuit arrangement for firing controlled, parallel-connected electric valves
    US3424972A|1969-01-28|Device for transmitting control pulses to a rectifier
    US4039866A|1977-08-02|Thyristor control apparatus
    SU959206A1|1982-09-15|Apparatus for protecting three-phase electric installation against two-phase operation
    US4215309A|1980-07-29|High efficiency switching circuit
    US3973144A|1976-08-03|Thyristor trigger circuit enabled by thyristor forward voltage level
    US3281716A|1966-10-25|Transistor power supply
    同族专利:
    公开号 | 公开日
    FI73545B|1987-06-30|
    NO149870B|1984-03-26|
    JPS52137632A|1977-11-17|
    ZA772708B|1978-04-26|
    FI771477A|1977-11-13|
    US4152759A|1979-05-01|
    NO149870C|1984-07-04|
    JPS6137863B2|1986-08-26|
    AU2506777A|1978-11-16|
    SE7705212L|1977-11-13|
    FR2351531B1|1984-05-04|
    FI73545C|1987-10-09|
    DE2720942A1|1977-11-24|
    AU512512B2|1980-10-16|
    GB1558596A|1980-01-09|
    CA1082307A|1980-07-22|
    NO771714L|1978-05-25|
    FR2351531A1|1977-12-09|
    引用文献:
    公开号 | 申请日 | 公开日 | 申请人 | 专利标题
    NL294965A|1962-07-09|
    US3624483A|1970-08-24|1971-11-30|Honeywell Inf Systems|Switching regulator using low-voltage diodes|
    US3824441A|1973-01-02|1974-07-16|Honeywell Inf Systems|Multivoltage, regulated power supply with fault protection|
    US3852656A|1974-04-19|1974-12-03|Gen Motors Corp|Inverter fault protection and frequency limiting circuit|
    US4063306A|1976-09-24|1977-12-13|General Electric Company|Actively switched damping circuit|US4409465A|1981-04-24|1983-10-11|Osaka Transformer Co., Ltd.|Pulse arc welding method and device in which pulse current and background current have a constant current characteristic|
    EP0208822B1|1985-07-15|1989-10-04|Kraftelektronik AB|An electrostatic dust precipitator|
    US4769754A|1987-07-27|1988-09-06|Miller Electric Mfg., Co.|Stabilized welding power source including a series-resonant current-regulated converter using a transformer having an air-gapped core|
    GB2212677B|1987-11-16|1992-07-22|Sanyo Electric Co|An electric circuit for supplying controlled frequency electric power to a load|
    US6087626A|1998-02-17|2000-07-11|Illinois Tool Works Inc.|Method and apparatus for welding|
    TW445192B|1999-04-12|2001-07-11|Tri Tool Inc|Control method and apparatus for an arc welding system|
    US6698067B2|2002-01-30|2004-03-02|Thomas & Betts International, Inc.|Locking strap with handling structure|
    US6713708B2|2002-03-01|2004-03-30|Arcon Welding Llc|Portable drawn arc stud welding apparatus and method providing high current output in short time intervals|
    FI116758B|2004-02-18|2006-02-15|Abb Oy|Method and arrangement for charging the drive intermediate circuit|
    GB0610202D0|2006-05-23|2006-07-05|Pepperl & Fuchs Gb Ltd|Electrical barrier|
    CN103003019B|2010-05-28|2015-05-20|依赛彼公司|Short arc welding system|
    BR112012030269B1|2010-05-28|2019-07-02|Esab Ab|SYSTEM FOR CONTROLING A WELDING CURRENT IN A CURRENT WIDE ARC WELDING APPARATUS, SHORT ARC WELDING SYSTEM, AND METHOD FOR CONTROLING A POWER SUPPLY ON A WELDING ARC CONTINUOUS CURRENT FOR SHORT BOW WELDING|
    RU2470451C1|2011-11-01|2012-12-20|Федеральное государственное бюджетное образовательное учреждение высшего профессионального образования "Ульяновский государственный технический университет"|Single-phase semi-bridge transistor inverter|
    法律状态:
    优先权:
    申请号 | 申请日 | 专利标题
    GB19533/76A|GB1558596A|1976-05-12|1976-05-12|Inverters|
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