JP2005176532A - Digital type dc power supply control device and method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a digital type DC power supply control device capable of stably controlling a multiphase and multiplex chopper circuit for heavy current against switching noise due to a PWM pulse. <P>SOLUTION: The operation timing of an A/D converter 93 is shifted when a PWM command value (modulated wave) 91 is in a predetermined A area in conducting a DC current control system in a digital manner using a multiplex chopper, thus preventing an instable state of control by overlapping noise generation timing accompanied by ON/OFF operations of a semiconductor switch. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a digital DC power supply control apparatus and method, and more particularly, to a digital DC power supply control apparatus and control method provided with a multiphase multiple chopper.

  When supplying a DC current with little ripple and good stability to a semiconductor power converter, a series dropper type or a switching power source type is mainly adopted. In a DC power supply device for large current, a switching power supply type is often used to improve power conversion efficiency and to reduce the size of a semiconductor cooling device. As an example, there is an electromagnet power source of an accelerator.

  Patent Document 1 and Non-Patent Document 1 disclose a multiphase multi-chopper circuit that constitutes a large current power supply by a switching power supply type. In this case, N step-down choppers are connected in parallel, and this chopper unit divides the period T into N equal parts and operates by shifting the phase by T / N. In this case, although the circuit becomes relatively complicated, there are significant advantages such as reduction of output ripple and miniaturization of the smoothing reactor, which is a system that is easily adopted by a large power source.

  Since this DC power supply device is of an analog type, it can perform high-speed and high-precision current control and has a simple mechanism. However, when the adjustment function and optional function required by an actual device are incorporated, the circuit becomes large, adjustment and maintenance inspection are complicated, and the use of a large number of parts leads to high price. Therefore, there is a demand for a digital direct-current power supply control device that achieves improvements in miniaturization, operability, and maintainability, and has control performance equivalent to that of an analog type.

JP 2000-59990 A (Overall)

Proceedings of the 6th Annual Meeting of the Institute of Electrical Engineers of Tokyo, Ibaraki Branch: November pp. 163-164, 1998 (all)

  In a digital control device, it is common to use an A / D converter that converts an analog quantity into a digital quantity for detection of current, voltage, and the like. However, the problem here is switching noise peculiar to the switching power supply. The response speed of the semiconductor switch is fast, and the switching loss indicated by the voltage applied to both ends of the switch × current flow is small, but electromagnetic noise is generated with a sudden change in current. This noise can be mitigated with a general snubber, but it cannot be completely suppressed, and if measures are strengthened, cost increases.

  Here, considering the case of a digital control device, when the generated noise and the operation timing of the A / D converter overlap, correct data cannot be read due to the noise, and the control performance is greatly deteriorated.

  An object of the present invention is to provide a digital DC power supply control apparatus or method capable of avoiding the phenomenon that A / D conversion data becomes an inappropriate value due to switching noise in a multiple chopper circuit and capable of stable control. There is.

  The present invention relates to a DC power supply control device that performs switching control of a chopper at a timing obtained by comparing a carrier wave and a modulated wave, and converts an analog control amount detection value into a digital detection signal at the first phase of the carrier wave, When the wave is in a predetermined magnitude range, the analog control amount detection value is converted into a digital detection signal in the second phase of the carrier wave.

  In a preferred embodiment of the present invention, a symmetric triangular wave is used as a carrier wave, and the A / D conversion operation is basically performed at the apex of a specific carrier triangular wave, that is, the center of a pulse among a plurality of carrier waves. Then, in the control command area where the A / D conversion operation and the noise generation timing overlap, switching is performed so that the A / D conversion operation is performed at the phase of the apex of the different (other) carrier triangular wave.

  According to the present invention, it is possible to provide a digital DC power supply control device that removes the operation timing of A / D conversion from the noise generation timing and obtains stable control performance in the digital control of the multiphase multiple chopper.

  Other objects and features of the present invention will be clarified in the embodiments described below.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

  FIG. 1 is an overall configuration diagram of a digital DC power supply control device showing an embodiment of the present invention, and shows an example of a DC power supply device using an N-phase N multiple chopper. First, alternating current from the alternating current power source 1 is converted into direct current by the rectifier 2. Therefore, these 1 and 2 constitute a DC power supply, and the DC output voltage is applied to the step-down chopper 3 and switched. The chopper converter 3 includes N unit choppers to reduce output ripple, and is configured as an N-phase N multiple chopper converter. As is well known, the chopper converter 3 includes a high-speed switching element such as an IGBT and a free wheel diode, and its output is smoothed by the DC filter 4. The DC filter 4 includes a DC reactor 41 (411 to 41N) and an output passive filter capacitor 42, and both ends of the filter capacitor 42 are connected to the load 5.

  The high-speed switching element of the chopper converter 3 is switching-controlled by a pulse width modulation (PWM) control unit 7 via a gate circuit 6. The PWM control unit 7 receives the N-phase carrier waves 81 to 8N from the carrier wave generation unit 8, and receives a modulated wave, that is, a PWM command value 91 from the digital control device 9. The PWM control unit 7 creates a switching pulse based on the carrier waves 81 to 8N and the modulated wave (PWM command value) 91 and transmits the switching pulse to the gate circuit 6.

The digital control device 9 basically constitutes a current control system. The current command unit 92 outputs a digital current command Id ^* . The load current I of the main circuit is detected by the current detector 10 and smoothed by the filter 11 to obtain an analog current detection signal Ia. The analog current detection signal Ia is converted into a digital current detection signal Id by an analog / digital converter 93. This conversion timing is determined by a timing signal 121 provided from the timing adjustment unit 12. In the current control system, the comparison unit 94 compares the digital current command Id ^* with the digital current detection signal Id and transmits the current deviation to the current control unit (ACR) 95. The output of the current control unit (ACR) 95 becomes a PWM command value (modulated wave) 91.

  The timing adjustment unit 12 includes four comparison reference voltage sources 122 to 125 and a capture timing adjustment circuit 126, and controls an A / D conversion operation at a timing that does not overlap with noise as will be described later.

  As described in Patent Document 1, it is desirable to provide a voltage control system called minor AVR inside the current control system (ACR), but here, illustration is omitted to avoid complication. .

  Here, the relationship between the switching noise and the A / D conversion timing of the control amount detection value in the chopper or the A / D conversion data fetch timing will be described.

  FIG. 2 is a waveform diagram showing the timing relationship between the data acquisition of the A / D converter and the PWM control operation in the 1-phase 1-multiplex chopper. When capturing the data to be detected with the minimum number (1) of A / D converters, avoid the noise that occurs when the pulse is turned ON / OFF, and the command value is small, the pulse width is narrowed, and the output current is reduced. It is necessary to avoid taking in the current value in the current intermittent interval where it becomes zero. For this reason, as shown in the drawing, an A / D conversion timing signal is generated at a phase of a valley of a carrier wave that is a symmetrical triangular wave, and A / D conversion is executed. In this way, the normal PWM command value 21 can be A / D converted at the intermediate timing of the PWM pulse, and there is no risk of being affected by noise. In the case of the PWM minimum command value 22 shown in the figure, the PWM pulse width becomes very narrow, and the A / D conversion timing signal overlaps with switching noise generated at the edge of the PWM pulse, so that accurate data reading is impossible. It is possible to become. However, in this case, since the output current is originally very small and the energy of the generated noise is small, it can be removed by providing a simple filter circuit before the A / D converter.

  FIG. 3 is an operation timing waveform chart of A / D conversion and PWM control in the two-phase double chopper circuit. The same applies to a two-phase double chopper, as shown in the figure, an A / D conversion timing signal is generated at a phase of a valley of a carrier wave that is a symmetrical triangular wave, and A / D conversion is executed. In this way, the normal PWM command value 21 can be A / D converted at the intermediate timing of the PWM pulse, and there is no risk of being affected by noise. In the case of the PWM minimum command value 22, it is a minute current and can be solved in the same manner as one phase single. In addition, although the timing overlaps with the noise even in the vicinity of the PWM maximum command value 23, it is not normally used at such a large conduction ratio due to the restriction of the minimum OFF time of the semiconductor switching element, and the command value is in a range below this. It is common to vary. Therefore, even in the case of the maximum command value that is normally used, the A / D conversion timing signal does not overlap with the switching noise.

  FIG. 4 is an operation timing waveform diagram of A / D conversion and PWM control in the three-phase triple chopper circuit. When the PWM command value becomes about 2/3 with respect to the amplitude of the carrier waves 81 to 83, the timing of A / D conversion and noise overlap. In the figure, the value of the PWM command value 21 is out of the region A of about 2/3 with respect to the amplitude of the carrier wave. As is apparent at the time T21, the noise is the same as in FIGS. There is no problem of overlapping. However, when the PWM command value becomes a value indicated by 24, the switching noise that appears in the current overlaps with the A / D conversion timing signal, as is apparent from time T24.

  In this case, unlike the case of the minute current in FIGS. 2 and 3, the switching current itself is large, and there is a risk that noise will be added to the entire control circuit including the power supply for the control circuit. There is a risk that it will be difficult to import data. In the case of a DC power supply, unlike the operation of an AC power supply such as an inverter, once the command value is determined, the PWM command value 24 is fixed within a certain range. At this time, in the case where the operation timing signal of the A / D converter overlaps with the ON / OFF edge of the PWM pulse, appropriate data cannot be acquired by the A / D converter, and the operation becomes unstable.

  This problem can be avoided by enhancing the noise resistance of the power supply circuit and increasing the frequency of A / D conversion, or increasing the number of A / D converters to increase the number of sampling points, thereby reducing the control performance. . However, since the number of parts is greatly increased, the merit of digitization described above is lost.

  In the examples of FIGS. 2 and 3, it should be noted that the average value of the output current can be captured even if the output current includes a lot of ripples. As is apparent from FIG. 4, even in a multiple chopper circuit of three or more phases and three multiplexes, since the output current naturally includes ripples, A / D conversion is simply performed immediately after the occurrence of noise. However, an average value is not obtained, and appropriate data acquisition is not possible.

  As described above, the range of the PWM command value that causes a problem due to noise superimposition is clear in advance. Therefore, if the range falls within this range, the timing for A / D conversion may be switched. In FIG. 4, when the magnitude of the PWM command value is about 2/3 of the amplitude of the carrier waves 81 to 83 and enters the region A, the A / D conversion timing at the bottom of the first phase carrier wave 81 is , Superimposed with noise. However, it can be seen from FIG. 4 that an appropriate value or approximate value can be obtained by switching the A / D conversion timing to the top of the second or third phase carrier wave 82 or 83.

  FIG. 5 is a specific circuit example of the timing adjustment unit 12 and its periphery according to an embodiment of the present invention. The timing adjustment unit 12 in FIG. 1 includes four comparison reference voltage sources 122 to 125 and a capture timing adjustment circuit 126. The timing adjustment circuit 126 includes comparison units 51 to 54, NAND gates 58 and 59, and an OR gate 60. It has.

  FIG. 6 is an operation timing waveform diagram of A / D conversion and PWM control of the three-phase three-multiplex chopper according to one embodiment of the present invention.

  The operation of this embodiment will be described below with reference to FIGS. First, in order to determine the A / D conversion timing at the normal time, the comparison unit 51 compares the first phase carrier wave 81 with the comparison reference value 122 to generate the timing signal 55 of the normal first phase. Further, in order to determine the A / D conversion timing at the time of switching, the comparison unit 52 compares the second phase carrier wave 82 with the comparison reference value 125, and prepares a timing signal 56 of the second phase at the time of switching. On the other hand, the comparison units 53 and 54 compare the PWM command value 91 with the comparison reference values 123 and 124, determine whether the PWM command value 91 is outside or inside the region A, and output an A region signal 57. Thereby, it is determined whether or not the A / D conversion timing overlaps with ON / OFF of the PWM pulse, and if not overlapped, the signal 55 is output as the A / D conversion timing signal 121. To do. That is, as shown in FIG. 6, if the PWM command value 91 is outside the region A, A / D conversion is performed at the bottom of the first phase carrier wave 81 as at time T55, and the PWM command value 91 is within the region A. If so, A / D conversion is performed at the top of the second phase carrier wave 82 at time T56.

  This timing adjustment unit 12 avoids overlapping of A / D conversion timing and switching noise, and an appropriate A / D conversion value is obtained near the amplitude center of the output current ripple, thereby enabling stable control. .

This embodiment is summarized as follows. First, as a main circuit, a step-down chopper 3 including a plurality of unit choppers 31 to 3N for switching direct currents from direct current power sources 1 and 2 with a phase difference, and a filter 4 for smoothing the output of the chopper and supplying it to a load 5 are provided. ing. As a control system, first, a carrier wave generation unit 8 that generates a plurality of carrier waves 81 to 8N and a current control unit 95 that generates a PWM command value (modulated wave) 91 corresponding to a current deviation are provided. A DC power supply control device including a PWM control unit 7 that performs switching control of the plurality of unit choppers 31 to 3N at timings obtained by comparing the plurality of carrier waves 81 to 8N and the PWM command value 91 is assumed. Here, a current command unit 92 that generates a digital current command signal Id ^* , current detection units 10 and 11 that detect the load current I and output an analog current detection signal Ia, and this analog current detection signal are detected by digital current detection. An analog / digital conversion unit 93 that converts the signal Id is provided. Usually, when the digital current detection signal Id is captured at the bottom of the first carrier 81 among the plurality of carriers, and the PWM command value 91 is in a predetermined range A, the digital current is detected at the top of the second carrier 82. A timing signal 121 for capturing the detection signal Id is output. The timing signal 121 is generated by the timing adjustment unit 12 and includes digital current control units 94 and 95 that compare the digital current command signal Id ^* with the captured digital current detection signal Id and output the PWM command value 91. ing.

  According to this embodiment, the phenomenon in which the A / D conversion operation of the feedback signal becomes an inappropriate value due to noise superposition, which is a problem when the multiphase multiple chopper is controlled using the digital control device, is relatively simple. It can be improved with a simple mechanism. Therefore, control performance equivalent to that of analog control can be ensured, and at the same time, the control unit can be reduced in size, maintainability and operability can be improved by taking advantage of digital control.

  In the above embodiment, the A / D conversion timing in the middle of the pulse is set to the top of the carrier wave (valley bottom or top) that can be easily set. However, when the A / D conversion near the center of the pulse becomes four-phase quadruple or more. It is not always effective, and an appropriate carrier and phase should be selected.

  In the present embodiment, the improvement method in the three-phase, three-multiplex step-down chopper circuit has been described. Even when N is 4 or more, by appropriately selecting the carrier to be switched, at the top of the carrier (the valley bottom or the top), Similarly, A / D conversion can be performed. Further, the present invention can be similarly applied to a step-up chopper circuit. Furthermore, although it has been described that the execution timing of the A / D conversion operation itself is switched, it is needless to say that the A / D converter is always operated and the output fetch timing is switched.

1 is an overall configuration diagram of a digital DC power supply device showing an embodiment of the present invention. FIG. 3 is an operation timing waveform diagram of A / D conversion and PWM control of a 1-phase 1-multiplex chopper. The operation timing waveform diagram of A / D conversion and PWM control of a two-phase two-multiplex chopper. The operation timing waveform diagram of A / D conversion and PWM control of a three-phase three-multiplex chopper. 4 is a specific circuit example of a timing adjustment device according to an embodiment of the present invention. FIG. 4 is an operation timing waveform diagram of A / D conversion and PWM control of a three-phase three-multiplex chopper according to an embodiment of the present invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... AC power source, 2 ... Rectifier (forward conversion), 3 ... Step-down chopper, 31-3N ... Unit chopper, 4 ... Filter, 41 (411-41N) ... DC reactor, 42 ... Output passive filter capacitor, 5 ... Load , 6 ... Gate circuit, 7 ... Pulse width modulation (PWM) control unit, 8 ... Carrier wave generation unit, 81-8N ... Carrier wave, 9 ... Digital control device, 91 ... PWM command value (modulation wave), 92 ... Digital Current command unit, 93 ... analog / digital (A / D) converter, 94 ... comparison unit, 95 ... current control unit (ACR), 10 ... current detector, 11 ... filter, 12 ... timing adjustment unit, 121 ... A / D conversion or A / D conversion signal capturing timing signal, 122 to 125... Comparison reference voltage source, 126... Capturing timing adjusting circuit, 21 to 25... PWM command value, 51 to 5 ... comparing unit, 55 ... first phase timing signal, 56 ... second phase timing signal, 57 ... A domain signals, 58 and 59 ... NAND gate, 60 ... OR gate.

Claims (7)

  A plurality of choppers that switch a direct current from a DC power source with a phase difference, a filter that smoothes the combined output of the plurality of choppers to supply to a load, a carrier wave generating unit that generates a carrier wave, and a PWM command corresponding to a control deviation In a DC power supply control device comprising: a control unit that generates a value (modulated wave); and a PWM control unit that performs switching control of the chopper at a timing obtained by comparing the carrier wave and the PWM command value. An analog control amount detection value is converted into a digital detection signal at a phase of 1, and an analog control amount detection value is digitally converted at a second phase of the carrier wave when the PWM command value is within a predetermined range. An A / D conversion unit for converting the detection signal into a detection signal and a digital control unit for controlling the control amount based on the digital detection signal are provided. Digital DC power supply control apparatus according to claim.   A plurality of choppers that switch a direct current from a DC power source with a phase difference, a filter that smoothes the combined output of the plurality of choppers to supply to a load, a carrier wave generating unit that generates a carrier wave, and a PWM command corresponding to a control deviation In a DC power supply control device comprising: a control unit that generates a value (modulated wave); and a PWM control unit that performs switching control of the chopper at a timing obtained by comparing the carrier wave and the PWM command value. A control command unit that generates a signal, a control amount detection unit that detects an output control amount and outputs an analog signal, an A / D conversion unit that converts the analog signal into a digital signal, and a first predetermined carrier wave When the digital output signal of the A / D converter is captured in phase and the PWM command value is in a predetermined size range, A timing adjustment unit that outputs a timing signal that captures the digital output signal of the A / D conversion unit at a second phase of the wave, and a digital control amount detection signal that is captured by the digital control command signal and the timing signal And a digital control unit for outputting the PWM command value.   A plurality of choppers that switch DC from a DC power source with a phase difference, a filter that smoothes the combined output of these choppers and supplies it to a load, a carrier wave generating unit that generates a carrier wave, and a PWM command corresponding to the current deviation In a DC power supply control device comprising: a current control unit that generates a value (modulated wave); and a PWM control unit that performs switching control of the chopper at a timing obtained by comparing the carrier wave and the PWM command value. A current command unit that generates a command signal, a current detection unit that detects a load current and outputs an analog current detection signal, an A / D conversion unit that converts the analog current detection signal into a digital current detection signal, The digital current detection signal is captured at a predetermined first phase of the carrier wave, and the PWM command value has a predetermined magnitude. A timing adjustment unit that captures the digital current detection signal at a predetermined second phase of the carrier wave, and compares the digital current command signal with the captured digital current detection signal. A digital DC power supply control device comprising a digital current control unit for outputting a command value.   A plurality of choppers that switch a direct current from a DC power source with a phase difference, a filter that smoothes the combined output of the plurality of choppers to supply to a load, a carrier generation unit that generates a plurality of carriers, and a control deviation DC power supply control comprising: a control unit that generates a PWM command value (modulated wave); and a PWM control unit that controls the switching of the plurality of choppers at a timing obtained by comparing the plurality of carrier waves with the PWM command value In the apparatus, a control command unit that generates a digital control command signal, a control amount detection unit that detects a control amount and outputs an analog detection signal, and an A / D conversion unit that converts the analog detection signal into a digital detection signal; The digital detection signal is captured at a predetermined phase of the first carrier among the plurality of carriers, and the PWM command value A timing adjustment unit that captures the digital detection signal at a predetermined phase of a second carrier among the plurality of carriers when the range is within a predetermined size, and the digital control command signal and the timing adjustment unit A digital DC power supply control device comprising a digital control unit for comparing digital detection signals and outputting the PWM command value.   5. The carrier generation unit according to claim 1, wherein the carrier wave generation unit generates a plurality of left and right symmetrical triangular waves, and the first and second phases are the phases of the vertices of two different triangular waves among the plurality of triangular waves. A digital DC power supply control device characterized by the above.   A step-down chopper including a plurality of unit choppers that switch DC from a DC power supply with a phase difference, a filter that smoothes the output of the chopper and supplies it to a load, a carrier generation unit that generates a plurality of carriers, and a current deviation A current control unit that generates a PWM command value (modulated wave), and a PWM control unit that controls switching of the plurality of unit choppers at a timing obtained by comparing the plurality of carrier waves and the PWM command value. In a DC power supply control device, a current command unit for generating a digital current command signal, a current detection unit for detecting a load current and outputting an analog current detection signal, and A for converting the analog current detection signal into a digital current detection signal The digital current detection signal at a predetermined phase of the first carrier among the plurality of carriers. And a timing adjustment unit that outputs a timing signal that captures the digital current detection signal at a predetermined phase of the second carrier among the plurality of carriers when the PWM command value is in a predetermined magnitude range; A digital DC power supply control device comprising a digital current control unit that compares the digital current command signal with a digital current detection signal captured by the timing signal and outputs the PWM command value. DC is switched with a phase difference by a plurality of choppers, the combined output of these choppers is smoothed and supplied to a load, a plurality of carrier waves are generated, a PWM command value (modulated wave) corresponding to a control deviation is generated, A control method for a DC power source that controls switching of the plurality of choppers at a timing obtained by comparing a plurality of carrier waves with the PWM command value, the step of generating a digital control command signal, and detecting a control amount Outputting an analog detection signal; converting the analog detection signal into a digital detection signal; capturing the digital detection signal at a first phase of the carrier; and a range in which the PWM command value has a predetermined magnitude And capturing the digital detection signal at a second phase of the carrier; and It compares the digital detection signal taken as control command signals digital, digital DC power supply control method comprising the step of outputting the PWM command value.

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