JP5228609B2 - Power supply - Google Patents

Description

The present invention relates to a power supply apparatus that converts an AC voltage from an AC power source into a DC voltage and supplies the DC voltage to a load.

  Conventionally, as a power supply device that converts an AC voltage from an AC power supply into a DC voltage and supplies it to a load, a zero cross point of the AC power supply is detected, and the AC power supply is short-circuited once or a plurality of times in a half cycle of the power supply via a reactor. Thus, it has been proposed to obtain a high DC output voltage while improving the power factor (see, for example, Patent Document 1 and Patent Document 2).

  FIG. 8 shows a configuration of a conventional power supply device described in Patent Document 1. In FIG.

  As shown in FIG. 8, the power supply device described in Patent Document 1 includes an AC power supply 1, a first diode bridge 31 that rectifies an AC voltage from the AC power supply 1, smoothing capacitors 32, 33, and 34. The second diode bridge 35 and the switching element 36 are connected to both ends of the AC power supply 1 via the reactor 6.

  Further, a power factor improving unit 37, a zero cross detecting unit 38, and an inverter control unit 23 are provided in the control means 39. The zero cross detection unit 38 is connected to both ends of the AC power source 1 and detects a zero cross point of the AC power source 1. The power factor improving unit 37 short-circuits the switching element 36 for a predetermined time from the detected zero cross point every half cycle of the AC power supply 1 and then opens it.

  As a result, the conduction width of the input current from the AC power supply 1 is expanded, the power factor is improved, and the energy stored in the reactor 6 is supplied to the smoothing capacitors 32, 33, 34, so that normal voltage doubler rectification is achieved. A DC output voltage higher than that of the circuit can be obtained.

  Further, the conventional power supply device described in Patent Document 1 includes an inverter circuit 21 and an electric motor 22 driven by the inverter circuit 21 as loads, and pulse width modulation control in an inverter control unit 23 that controls the inverter circuit 21. By determining the short circuit start time and the short circuit period of the switching element 36 based on the duty ratio of the signal, the power factor can be improved according to the load state.

  FIG. 9 shows a configuration of a conventional power supply device described in Patent Document 2. In FIG.

As shown in FIG. 9, this power supply device can improve a power factor and can suppress a harmonic by short-circuiting the switching means 40 several times for every half cycle of AC power supply 1. FIG.
Japanese Patent Laid-Open No. 10-201248 Japanese Patent No. 3485047

  However, in the conventional power supply device, the AC power supply short circuit start timing determined by the elapsed time (delay time) from the zero crossing point of the AC power supply is set to a load such as the duty ratio of the PWM signal of the inverter circuit or the torque of the load motor. Although the calculation is performed by a function set in advance according to the state, the frequency fluctuation of the AC power supply is not taken into consideration at that time.

  Therefore, when connected to an AC power source, such as a private generator, where power supply frequency fluctuations are likely to occur compared to a commercial power supply connected to the grid, a conventional power supply device is a power supply that short-circuits the AC power supply when the power supply frequency changes. Due to the phase shift, distortion of the input current tends to increase.

  In particular, in a power supply device that short-circuits / opens an AC power supply through a reactor multiple times in a half cycle of the AC power supply, the switching element is short-circuited / opened at a voltage phase where the peak value of the AC power supply is high due to a short-circuit timing shift. A high current peak is likely to occur, and as a result, the power factor is lowered and the influence on the current distortion is likely to be remarkable.

  The present invention solves the above-described conventional problems, and a first object of the present invention is to provide a power supply device that stably realizes a high power factor operation even when the power supply frequency fluctuates. In a state where the state is unstable, the second object is to reduce the burden on the AC power supply by limiting the boosting performance of the power supply device in order to avoid a power failure.

  In order to solve the above-described conventional problems, the power supply device of the present invention includes a rectifier circuit that rectifies an AC voltage from an AC power supply, a reactor connected in series to the AC power supply, and a short circuit between the AC power supply via the reactor. The switching means to be opened, the voltage phase detection means for generating a pulse signal synchronized with the AC power supply, and the control means for driving the switching means based on the output signal of the voltage phase detection means, are synchronized with the voltage phase of the AC power supply. A power supply device that short-circuits / opens the AC power supply by the switching means via the reactor once or a plurality of times during a half cycle of the AC power supply, and the cycle of the pulse signal obtained from the voltage phase detection means is predetermined. Only when it is within the range from the first predetermined time to the second predetermined time, the short-circuiting / opening operation is performed a plurality of times.

  According to the power supply device of the present invention, when the power supply frequency of the AC power supply is within a predetermined range, a high power factor improvement effect and a boosting capability are realized by performing a short-circuit operation a plurality of times during a power supply half cycle. At the same time, when the power supply frequency is outside the predetermined range, the influence of the input current distortion due to the short-circuit timing deviation can be reduced or eliminated by short-circuiting once or stopping the short-circuiting operation during the half-cycle of the power supply.

  The first invention is a rectifier circuit for rectifying an AC voltage from an AC power supply, a reactor connected in series to the AC power supply, a switching means for short-circuiting / opening the AC power supply through the reactor, and a synchronization with the AC power supply. A voltage phase detecting means for generating a pulse signal, and a control means for driving the switching means based on the output signal of the voltage phase detecting means, or once in a half cycle of the AC power supply in synchronization with the voltage phase of the AC power supply or A power supply device that short-circuits / opens an AC power supply by a switching means via a reactor a plurality of times, wherein the control means has a pulse signal cycle obtained from the voltage phase detection means from a predetermined first predetermined time. Only when it is within the range up to the second predetermined time (first predetermined time <second predetermined time), the short-circuiting / opening operation is performed a plurality of times.

  Thereby, when the power supply frequency is outside the predetermined range, the influence of the input current distortion due to the short-circuit timing shift can be reduced by limiting the number of short circuits between the power supply half cycles to 1 or less.

According to a second aspect, in the first aspect, the switching is performed when the period of the pulse signal obtained from the voltage phase detection means is shorter than the third predetermined time set to a value equal to or less than the first predetermined time. By controlling the means to the open state, when the power supply frequency of the AC power supply becomes too high, the boosting function can be stopped and only the minimum operation (rectification operation) can be continued.

  According to a third aspect, in the second aspect, switching is performed when the period of the pulse signal obtained from the voltage phase detection means is longer than a fourth predetermined time set to a value equal to or greater than the second predetermined time. By controlling the means to the open state, when the power supply frequency of the AC power supply becomes too low, the boosting function can be stopped and only the minimum operation (rectification operation) can be continued as in the second invention. .

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that the present invention is not limited to the embodiments.

(Embodiment 1)
FIG. 1 is a block configuration diagram showing a configuration of a power supply device according to Embodiment 1 of the present invention.

  As shown in FIG. 1, the power supply device of the present invention includes a rectifier circuit 2 that rectifies an AC voltage of an AC power supply 1, and includes one of the AC input ends of the rectifier circuit 2 and one DC input end of the rectifier circuit 2. The first capacitor 3 connected in between and the second capacitor 4 connected between the same AC input terminal of the rectifier circuit 2 and the other DC input terminal of the rectifier circuit 2 are connected to the load 5 with a DC voltage. The voltage doubler rectifier circuit for supplying

  Furthermore, a reactor 6 is connected between the AC power source 1 and the AC input terminal of the rectifier circuit 2, and a bidirectional switching means 7 composed of a semiconductor element such as a diode bridge or MOSFET / IGBT is provided via the reactor 6. The AC power supply 1 is connected to a position where it is short-circuited.

  The voltage phase detection means 8 is connected to both ends of the AC power supply 1 and outputs a pulse signal synchronized with the voltage phase of the AC power supply 1.

  The control means 9 is constituted by a microcomputer or the like, and the period T of the output pulse signal from the voltage phase detection means 8 measured by the period detection unit 9a and a plurality of times (T1 to T1) stored in advance in the storage unit 9b. T4) is compared with the short-circuit number determination unit 9c, and the number of times the switching means 7 is short-circuited during the power supply half cycle is determined.

  Further, the control means 9 generates a drive signal for driving the switching means 7 by using the pulse signal output from the voltage phase detection means 8 as a timing reference in the drive signal generation section 9d, so that every half cycle of the power supply The switching means 7 is repeatedly short-circuited / opened by the number of short-circuits determined by the short-circuit number determination unit 9c.

  FIG. 2 is an example of a flowchart of the short circuit number determination unit 9c.

  As shown in FIG. 2, the control means 9 has a period T of the pulse signal output from the voltage phase detection means 8 that is equal to or longer than a first predetermined time T1 stored in the storage unit 9b in the control means 9 in advance. When it is in the range of the second predetermined time T2 or less, the power supply device operates with an input current waveform that provides a high power factor and high boosting capability by setting the number of short circuits between the power supply half cycles to five. .

  Further, the period T of the pulse signal output from the voltage phase detection means 8 is shorter than the third predetermined time T3 set to a value equal to or shorter than the first predetermined time T1, or equal to or longer than the second predetermined time T2. If it is longer than the fourth predetermined time set to the value, the state of the AC power supply 1 is regarded as unstable, the number of short circuits is set to 0, and the switching means 7 is controlled to be in the open state.

  When the period T is other than the above, the minimum number of boosting performances can be ensured while avoiding distortion of the input current waveform due to the switching timing deviation by limiting the number of short circuits between the power supply half periods to one.

  FIG. 3 shows an example of a specific circuit of the voltage phase detection means 8 in the present invention.

  As shown in FIG. 3, the voltage phase detector 8 includes an AC input photocoupler 10 and resistors 11, 12, and 13.

  The voltage phase of the AC power supply 1 at which the photocoupler 10 is turned on is adjusted by a resistor 11 and a resistor 12 connected to the primary side of the photocoupler 10.

  On the secondary side of the photocoupler 10, the collector of the output transistor is pulled up by the resistor 13 and connected to the input port of the control means 9 which is a microcomputer.

  FIG. 4 is a timing chart showing the relationship between the output pulse signal of the voltage phase detection means 8 and the drive signal of the switching means 7 when the number of short circuits during the power supply half cycle is one.

  The control means 9 is based on the time Td determined in advance according to the state of the load 5 from the timing at which the edge corresponding to the end of the pulse signal from the voltage phase detection means 8 (rising edge in FIG. 4) is detected. The switching means 7 is controlled so that the short-circuit operation of the switching means 7 is started after the time Td has elapsed, and then opened after the time Tw.

  The time Tw may be a value set in advance according to the state of the load 5, such as current and motor rotation speed, or adjusted by feedback control so that the DC output voltage of the power supply device becomes equal to a predetermined target voltage. May be.

  FIG. 5 is a timing chart showing the relationship between the output pulse signal of the voltage phase detection means 8 and the drive signal of the switching means 7 when the number of short circuits during the power supply half cycle is five.

  The control means 9 detects a time Tdn (n = 1) determined in advance according to the state of the load 5 from the timing at which an edge (rising edge in FIG. 5) corresponding to the end of the pulse signal from the voltage phase detection means 8 is detected. -5), the short-circuiting operation of the switching means 7 is started after the time Tdn (n = 1 to 5) has elapsed, and then the time Twn (n = 1 to 5) (not shown in FIG. 5). ) The switching means 7 is controlled to be opened later.

  The time Twn (n = 1 to 5) may be a value set in advance according to the state of the load 5 as in the case where the number of short circuits is one, or the DC output voltage of the power supply device may be a predetermined target. You may adjust by feedback control so that it may become equal to a voltage.

  6A to 6D show examples of input current waveforms in the power supply device of the present invention.

  As shown in FIGS. 6A and 6B, when the power supply frequency is 50 Hz and 55 Hz, a high power factor current waveform (power factor of about 99%) is obtained by performing switching operation five times in the power supply half cycle. It has gained.

  FIG. 6C shows an input current waveform when the power supply frequency is further increased, the period T of the pulse signal of the voltage phase detection means 8 is less than T1, and the switching operation is performed once in a half period of the power supply. .

  FIG. 6 (d) shows the input current waveform when the power supply frequency is lowered and the period T of the pulse signal of the voltage phase detection means 8 exceeds T2, so that the switching operation is performed once in a half cycle of the power supply. It is.

  In both cases of FIGS. 6C and 6D, by suppressing the number of short circuits to one, it is possible to avoid switching at a voltage phase where the peak value of the power supply voltage is high due to a short circuit timing shift. It can be seen that the current is maintained at a relatively high power factor.

  Although not shown, in the power supply device of the present invention, the cycle T of the pulse signal of the voltage phase detection means 8 is 8.333 ms (corresponding to a half cycle at 60 Hz) or less, or 12.5 ms (half at 40 Hz). When it becomes equal to or more than the period, the switching means 7 is controlled to be in an open state.

  At this time, the input current has a well-known waveform at the time of capacitor input, and the load on the AC power supply 1 is reduced by completely stopping the boosting performance of the power supply device.

  In this embodiment, the voltage phase detection means 8 outputs a pulse signal once every half cycle of the AC power supply 1 as shown in FIG. The voltage phase detection means 8 employs a circuit that outputs a pulse signal once in one cycle of the AC power supply 1, and the cycle T of the pulse signal is equal to the power cycle. Needless to say, the same effect can be obtained in this case.

  As described above, in the first embodiment, the AC power source 1 is relatively stable by switching the number of short circuits between the power source half cycles according to the cycle T of the output pulse signal of the voltage phase detector 8. Has a high power factor and high boosting capability, and when the power supply frequency deviates significantly from the standard frequency and the AC power supply 1 is considered unstable, the short-circuit operation of the switching means 7 is temporarily stopped. Thus, the burden on the power supply can be minimized.

  In the configuration of the power supply device according to the first embodiment, the voltage doubler rectifier circuit has been described as shown in FIG. 1, but the same effect can be obtained even with a full-wave rectifier circuit as shown in FIG. It goes without saying that it is obtained.

  As described above, the power supply device according to the present invention can stably realize a high power factor operation even when the power supply frequency of the AC power supply fluctuates, so domestic and foreign air conditioners and heat pump water heaters, Applicable to electric appliances such as refrigerators and washing machines.

1 is a block configuration diagram of a power supply device according to Embodiment 1 of the present invention. Flow chart of the short-circuit number determination unit Circuit diagram showing an example of a specific circuit of the voltage phase detection means Timing chart showing the relationship between the output pulse signal of the same voltage phase detection means and the drive signal of the switching means (when the number of short circuits is one) Timing chart showing the relationship between the output pulse signal of the same voltage phase detection means and the drive signal of the switching means (when the number of short circuits is 5) (A) Input current waveform diagram in the case of 50 Hz of the power supply device in Embodiment 1 of the present invention (b) Input current waveform diagram in the case of 55 Hz (c) Input current waveform diagram in the case of 58.5 Hz ) Input current waveform at 5Hz Another block configuration diagram of the power supply device according to the first embodiment Block diagram of a conventional power supply Block diagram of another conventional power supply device

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 AC power supply 2 Rectifier circuit 5 Load 6 Reactor 7 Switching means 8 Voltage phase detection means 9 Control means T1 1st predetermined time T2 2nd predetermined time T3 3rd predetermined time T4 4th predetermined time

Claims (1)

A rectifier circuit that rectifies the AC voltage from the AC power supply, a reactor connected in series to the AC power supply, a switching means that short-circuits and opens the AC power supply via the reactor, and a voltage that generates a pulse signal synchronized with the AC power supply A phase detecting means and a control means for driving the switching means based on the output signal of the voltage phase detecting means, and being synchronized with the voltage phase of the AC power supply one or more times during a half cycle of the AC power supply via the reactor. The switching means short-circuits / opens the AC power supply, wherein the control means has a period of the pulse signal obtained from the voltage phase detection means from a predetermined first predetermined time to a second predetermined time. within the range of (first predetermined time <second predetermined time) only when it is in, had row shorting and opening operations of a plurality of times, the period of the pulse signal, the first When it is out of the range from the fixed time to the second predetermined time, the number of short-circuit / opening operations is limited to one, and the cycle of the pulse signal is set to a value equal to or less than the first predetermined time. The switching means is controlled to be in an open state when it is shorter than the third predetermined time and when it is longer than the fourth predetermined time set to a value equal to or greater than the second predetermined time. Power supply.

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