• 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:
    The power control circuit described functions to vary the duty cycle of the alternating current signal supplied to the load (12). The duty cycle is varied by periodically generating a first signal, each half cycle of the alternating current signal, that is proportional to the actual power supplied to the load (12) as a function of the duty cycle and wave form of the slternating current signal. A comparator (54) compares this first signal with an error signal to vary the duty cycle in accordance with the power demanded by the error signal. The first signal is derived by evaluating the integral of the square of the voltage over each half cycle of the alternating current signal.
    公开号:SU936834A3
    申请号:SU792734659
    申请日:1979-02-23
    公开日:1982-06-15
    发明作者:Тит-Синг Чоу Аллан
    申请人:Е.И. Дюпон Де Немур Энд Компани (Фирма)；
    IPC主号:
    专利说明:

    The invention relates to devices ’’ for controlling electric power and can be used in converting technology.
    Known devices for controlling 5 electric power, in which the power supplied to the load is regulated by controlling the voltage [1] and [2].
    Closest to the invention is a device for controlling the electric power supplied from an AC source to a load in accordance with an error signal, including a detector for switching an AC 1S current signal through zero and a control unit whose inputs are connected to the error generating unit and zero crossing detector.
    In this device, a circuit of raising> 20 to the square of the voltage generates a control signal proportional to the average value of the square of the voltage, and the proportional regulator compares the control signal with the error signal, thereby regulating the power supplied to the load [2].
    However, the device operates only on the average value of the square of the voltage, and for this reason it is somewhat limited in the degree of accuracy that can be obtained.
    The aim of the invention is to improve the accuracy of regulation of power supplied to the load.
    The goal is achieved in that the device for controlling the electric power supplied from the AC source to the load in accordance with the error signal, including a detector for transitioning the AC signal through zero and a control unit, the outputs of which are connected to the error generating unit and the detector for crossing through zero, at this control unit contains a voltage measuring device, in any form. current, a calculator for continuous calculation of the integral of the square of the voltage of each half of the period and a device for comparing the computing signal with the error signal, the output of the comparison device being the output of the control node.
    In FIG. · 1 shows a block diagram of a generalized view of a regulator, a device for controlling electric voltages — 3 constructed according to this invention, FIG. 2 is a partially block, partially circuit diagram of a controller (a device for controlling electric power), depicting a detailed translational part of the block diagram shown in FIG. 1) FIG. 3 is a waveform diagram showing a graph of the power supplied to the load versus the working period, which would describe how the power is regulated as a function of the switch response time.
    . In FIG. 1 shows a power control circuit in which power from a 2o source of AC voltage 1 (line voltage) is supplied to a load 2, which is shown as a resistive heating element. This element can be located in the 25th furnace 3, for example, an analytical instrument. Although power is shown as being supplied to a resistive load, it can also be supplied to other types of loads, including electric motors and 30 like ones. The circuit also includes a sensor 4, such as a thermocouple of the sample, which is located in the furnace 3 for measuring the temperature of the furnace and is a desired variable. 35
    In the case of a thermocouple reference junction 4 is provided 5 so that a voltage proportional to the temperature difference between the sample junction and a reference junction is passed through a resistor 6 to 40 summiruyu- neck Compound 7. To a summing junction setpoint signal supplied give a reference signal obtained from the device 8 set value. This reference signal can be a fixed 45th value or with a programmed value intended to obtain a setpoint or a reference signal that changes in such a way that it is desirable to change the adjustable s0 characteristics. This reference signal passes through a resistor 9 to the summing connection 7. The sum signal is applied through an amplifier 40 to the device for controlling the electric power 55 supplied to the load 11. The device 11, which can also be a regulator, produces a starting voltage signal, which is passed for control the corresponding switching device, such as triac 12, thereby changing the working period of the AC signal 1, which is applied to the load resistor 2. By changing the working period, you can change the power spine, supplied to the load. Regulator 11 (in known devices) is usually on>. opens a zero crossing detector and some circuits for changing the times following each transition point through zero, in which the triac 12 is turned on. In accordance with the invention, the regulator 11 is modified to switch the receiving pulses that occur at a time as a function of only the power to be supplied to the load, but also a function of the line voltage waveform. Consequently, more precise control of the power supplied to the load occurs.
    The AC terminals 1 (FIG. 2) are connected through a transformer 13 to a zero crossing detector 14, to a peak detector 15, and to circuit 16. phase shift of 90 °. A conventional zero crossing detector 14 provides a pulsed output signal at every instant of zero crossing of an AC wave. The detector 14 may be provided by any of the known types with integrated circuits or, for this case, using transistors. Peak detector 15 contains a standard series-connected diode, shunt capacitor circuit. The 90 ° phase shift pattern can be any of the commonly used.
    The outputs of circuits 14-16 are connected to a circuit designed in accordance with this invention for integrating the AC voltage applied to the output terminals 1. Is the output signal expressed by the Vsi'ni , where V is the peak value of the AC signal, and b is the 1 phase angle, which varies with each half-period from 0 to Tv. The actual power supplied to the resistive load is determined (Fig. 1), since the power is proportional to the square voltage in resistive load:
    PK / sin
    Ίϋ sA.
    -KU ^ P / 2 [1 - COS '! ®
    X KV2. 2
    In the resulting formula, the angle oL represents the angle from the transition point 5 through zero to the point at which the path actually operates, so that the resulting waveform that is generated by this circuit is shown in FIG. 3 and curve 10 is shown 17. According to this curve, if the response angle is early, that is, otpO. then the maximum power is supplied to the resistive load, while as the angle increases to 1 s of the next j point of transition through zero, the power is po-. decreases in accordance with the Z-shaped function 17. An error signal reflecting the power required for the load received from the amplifier 10 (Fig. 1) is fed through a resistor 18 to the comparator 19 (Fig. 2), to the second input terminal of which function 17 is supplied, Thus, when the error signal 20 (Fig. 3, dashed line) is equal to /-06.7 25 of different function 17, comparator 19 (comparison device) supplies an output pulse to triac 12 (Fig. 1) to turn on of the current-switching device, so that the power supplied for the remaining time of this period is significant chenie defined by the point of intersection with error signal 17 2 -shaped curve.
    The formation of this curve requires an almost sinusoidal input signal and is performed by solving the integral depicted above. For this, the first term of the integrable expression is obtained by supplying the output signal of the pin detector 15 to the squaring circuit 21, the output of which (K7EV 2 - / 2) is connected through the summing resistor 22 to the summing connection 23 to obtain the second term of the integrable expression. The output of the squaring circuit 21 is connected through a resistor 24 to the negative input of its integrator, which consists of an operational amplifier 25 and a feedback capacitor 26. An integrator feedback capacitor 50 or integrator feedback capacitor 26 is bridged by a switching transistor 27, in this case depicted as a field effect transistor, connected to receive the output signal 55 from the zero crossing detector 14 through an isolation capacitor 28. Thus, the output signal of the integrator circuit provides the second term (- RVAsi / 2) supplied through the resistor 29 to the summing compound 23.
    In order to eliminate problems in the case when the error signal exceeds the amplitude of the Z-shaped curve 17, the pulses from the zero-crossing detector 14 are also fed through a resistor 30 to the summing connection 23, so that at the beginning of each period the Z-shaped curve is changed when sharp peak 31 (Fig. 3) This ensures that it starts at or near zero, in the case of a very large error signal, so that the maximum power is applied to the load.
    The third term of the integrating expression is supplied by connecting the output signal of the phase shift circuit 16 by 90 ° together with the AC voltage to the inputs of the multiplier 32. The output signal of this circuit is the term (+ V 4 K / 4 9in2> 0. This output signal through the resistor. 33 connected to the summing connection 23. This summing connection is connected to an amplifier 34, the other output of which is grounded through a resistor 35. The output of the amplifier is connected to the input through an adjustable resistor 36 to determine the value of the gain, which is equal to the ratio resistance values 36 and 35. Thus, a summed output signal representing the instantaneous power supplied to the load, depending on operation at a certain angle, that is, a Z-shaped curve 17. This output signal or Z-shaped curve is applied through a resistor 37 to the first input of the comparator 19 (comparison device), which generates an output pulse when the amplitude of the Z-shaped curve is equal to the amplitude of the error signal applied to the second input of the comparator. Thus, the combination of devices 15 and 16 constitutes the voltage measuring device 38 for any form of current, and the combination of the device and elements 21-30 and 32-36 represents the calculator of the integral 39.
    When the comparison is made, yield - t hydrochloric pulse signal is applied to triacs 12 which performs the signal transmission in the appropriate time during each poluperioaa AC input signal.
    Thus, the proposed device has the ability to take into account
    936834 8 line voltage and even providing accurate output power in the load by adjusting the angle of operation of the switching device. This makes the device particularly useful * - $ for precise regulation of the heater of thermal analysis chambers, for example, the device provides automatic compensation for voltage changes so that it can be controlled dynamically. W a range of seven-fold linear on. voltage supply.
    'In an alternative embodiment of the invention, the controller 11 (Fig. 1) may be in the form of a microcomputer connected 15 valuable with read-only memory. (ROM) in memory. which stores the sine value lookup table synchronously with the AC signal. In the device, a peak detector is used to supply a peak> 20 g of voltage to the microcomputer. The function V r O can be integrated by a successive approximation. In this way, the same Z.-shaped curve is formed, which can be fed 25 pa to the comparator 19 to adjust the triac trigger point.
    In the invention, a microcomputer can be used to compute a sequence representing the
    VsiM 1 O, so that the interval in real time is calculated synchronously with the waveform. This output signal, which depends on the 7-shaped curve 17, can also be applied to the comparator ^ 19 to control the angle of operation.
    The present invention has the advantage of obtaining precise control, which varies as a function of the actual line voltage and ^ provides a very precisely adjusted value of the power in the load in accordance with the error signal.
    权利要求:
    Claims (2)
    [1]
    open source, the output of the device being compared is the output of the control node. and fkg. 1 is an imaginary block-: a hema of a generalized type of regulator, a device for controlling the electrical power constructed according to this invention; FIG. 2 is a partially block, partially schematic diagram of a regulator (device for controlling electric power), depicting the detailed translator part of the block diagram shown in FIG. 1J of FIG. 3 is a waveform, which shows a graph of the power supplied to the load, over the working period, in order to describe the way in which the power pe is controlled as a function of the operating time of the switch. . FIG. 1 is an image of a power control circuit in which the power from the SOURCE of the AC voltage 1 (linear voltage) is supplied to the Haj level 2, which is shown as a resistive heating element. This element may be located in the furnace 3, for example, an analytical instrument. Although the power is shown as being applied to the redistributive load, it can also be applied to other types of Hubs, including electric motors and the like. The circuit also contains a sensor 4, such as a sample thermocouple, which is located in the furnace 3 for measuring the temperature of the furnace and is the same variable. In the case of thermocouple 4, a reference junction 5 is provided, so that the voltage proportional to the temperature difference between the junction of the sample and the reference junction is transmitted through resistor 6 to summing connection 7. A set value signal is received from the specified value device 8. value. This reference signal may be a fixed value or with a programmed otherwise, designed to receive a predetermined value or reference signal, which changes in such a way that it is desirable to change the adjustable characteristics. This reference signal passes through the resistor 9 to the summing connection 7. The sum signal is applied from through the amplifier 10 to the device for controlling the electrical power supplied to the load 11. The device 11, which can also be a regulator, produces a starting Signal voltage that is passed for control & appropriate switching current device, such as a triac 12, thereby changing the operating period of the AC signal 1, which is applied to the load resistor 2. By looking at the working period, you can change the power nce supplied to the load. Regulator 11 (in known devices) is usually on. a zero crossing detector and some circuits for changing the time points following each transition point / zero crossing into which the triac 12 is inserted. In accordance with the invention, the controller 11 is modified to switch receive pulses that take place at the time instant as a function of not only the power to be supplied to the load, but also the function of the linear voltage waveform. Consequently, there is a more precise control of the power supplied to the load. The AC terminals 1 (Fig. 2) are connected via a transformer 13 to a zero crossing detector 14, to a peak detector 15 and to a circuit 16. phase shift of 90 °. A conventional zero-crossing detector 14 provides a pulse output signal at each instant of the zero-crossing of the AC wave. The detector 14 may be provided in any of the known types with integrated circuits or, for this case, using transistors. Peak detector 15 contains a standard series-connected diode, bypassing the capacitor circuit. The phase shift scheme of 90 can be any of the most commonly used. The outputs of circuits 14-16 are connected to a circuit designed in accordance with this invention to integrate the AC voltage applied to the output terminals 1. The output signal is expressed by the formula where V is the peak value of the AC signal and & the phase angle, which with each half-period varies from 0 to /. The actual power supplied to the resistive load is determined (Fig. 1), since the power is proportional to the square of the voltage in the resistive thread. load; .. P - K; cvs He) -a6 --KV f5iH ed-ts HoC 1 - COSiQj G-fe-sinl & l / ei2. -W. T, In the formula obtained, the angle oL is the angle from the point of transition 5 through zero to the point at which the actual actuation of the track takes place, so that the resulting waveform produced by this circuit. is depicted in fig. 3 and is represented by curve 17. According to this curve, if the angle of response is early, i.e.d.fsO. The maximum power is applied to the resistive load, while as the angle X- increases to the next zero crossing point, the power is continuously reduced in accordance with the 2. -shaped function 17. The error signal reflecting the power required for the load received from the amplifier 10 (Fig. 1) is supplied via resistor 18 to comparator 19 (Fig. 2), to the second input terminal of which function 1 is applied. Thus, when the signal of error 2O (Fig. 3, dashed line), is equal to different function 17, comparator 19 (comparison device) delivers output impulse for a triac 12 (fig. 1) to turn on this current switching device, so that the power supplied in the remaining time of this period has a value determined by the intersection of the error signal with an i-shaped curve 17. The formation of this curve requires an almost sinusoidal input signal and performed by solving the integral shown above. For this, the first term of the integrable expression is obtained by applying the output signal of the peak detector 15 to the squaring circuit 21, the output of which () is connected via summing resistor 22 to summing connection 23 to obtain the second term and the iterated expression. The output of the squaring circuit 21 is connected via a resistor 24 to the negative input of its integrator, which consists of an operational amplifier 25 and a feedback capacitor 26. The integrating capacitor or feedback capacitor 26 of the integrator is shunted by a switching transistor 27, in this case depicted as a pale-yellow transistor connected to output the output signal from the zero crossing detector 14 through the isolating capacitor 28. This is the output signal of the & 3eS circuit 46 the integrator provides the second term (- K / 2), fed through p. Resistor 29 to summing connection 23. In order to eliminate problems in the case where the error signal exceeds the amplitude of the Z-shaped curve 17, impulse from the zero crossing detector 14 is also supplied through the resistor ZO to the summing connection 23, so that at the beginning of each period the 2-shaped curve is changed when the sharp peak 31 is broken (Fig. 3). This guarantees starting at or near the zero crossing point in the case of a very large signal error, so that the maximum power is applied to the load. The third term of the integrator is supplied by connecting the output signal of the phase shifting circuit 16 to 90 together with the AC voltage to the inputs of the multiplier 32. The output signal of this circuit is the term (. This output signal P® resistor. 33 is supplied to summing connection 23. This summing connection is connected to the amplifier 34, the other output of which is grounded through a resistor 35. The amplifier output is connected to the input through an adjustable resistor 36 to determine the gain value, which is equal to 36 and 35. TaKriM, summed output signal, representing the instantaneous power supplied to the load, depending on the response at a certain angle, i.e. Z-shaped curve 17. This output signal or Z-shaped curve It is fed through a resistor 37 to the first input of the comparator 19 (comparator), which produces an output pulse when the amplitude of the Z-shaped curve is equal to the amplitude of the error signal applied to the second input of the comparator. Thus, the aggregate of the devices 15 and 16 constitutes the device 38 for measuring voltage with any form of current, and the combination of the device and the elements 21-30 and 32-36 represents the calculator of the integral 39. a comparison, an output is performed. "The pulse signal is applied to a triac 12, which transmits the signal at the proper time during each half-period AC input signal. Thus, the proposed device has the ability to take into account deviations of the linear level and even provide accurate output power in the load by recirculating the YGL switching device operation. This makes the device especially for ee -. In order to precisely control the heater of the thermal analysis chambers, for example, the device provides an atomic compensation for changing the voltage, so that the foot controls the dynamic range of the sevenfold linear feedline. In an alternative embodiment of the invention, the controller 11 (Fig. 1) may be in the form of a microcomputer connected to a permanent memory. (ROM) in memory. which table is stored searching for sine values synchronously with the AC signal. The device uses a peak detector to supply a peak voltage to the microcomputer. V 51I & can be integrated by sequential approximation. In this way, the same X-shaped curve is formed, which can be supplied by commator 19 to adjust the triac's trigger point. In the invention, a microcomputer can be used to calculate a sequence representing functionally VsiVj 0, so 4VO calculates the interval in real time synchronously with the waveform. This output, which is dependent on the T. curve 17, will also be fed to comparator 19 for adjusting the trigger angle. The present invention has the npei power in obtaining precise control, which varies as a function of the actual linear voltage and provides very precisely regulated power values in the load in accordance with the signal oiibki. DETAILED DESCRIPTION OF THE INVENTION A device for controlling electrical power supplied from an alternating current source to a load in accordance with an error signal, comprising an alternating current signal crossing detector and a control node, the outputs of which are connected to an error shaping node and a zero crossing detector differing from ; l, that, in order to increase the accuracy, the control unit contains a voltage measuring device for any form of current, the calculator of continuous calculation and the integral of the kbadrat voltage of each n Olo: - period fault and device comparing the computational signal with the error signal g ki, the output of the comparator device being the output of the control node. Sources of information taken into account in the examination. Rudenko, V.S., et al. Conversion Technique. Kiev. Vshdr School, 1978, Ch. 2, § 2.11.
    [2]
    2. US patent No. 3553428, cl. H O2 M, 1978.
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    引用文献:
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    法律状态:
    优先权:
    申请号 | 申请日 | 专利标题
    US05/880,945|US4223207A|1978-02-24|1978-02-24|Apparatus for controlling the power supplied to a load|
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