JP5874019B2 - DC power supply - Google Patents

Description

  The present invention comprises a rectifier circuit that rectifies an AC voltage from an AC power supply, and switching means that short-circuits / opens (ON / OFF) the AC voltage from the AC power supply via a reactor, and provides a desired DC output voltage. The present invention relates to a DC power supply apparatus that controls voltage and controls an input current from an AC power supply to a predetermined waveform (such as a sine wave), and more particularly to an input current detection method in the DC power supply apparatus.

  The DC power supply device uses the switching means to turn on / off the AC voltage from the AC power supply via the reactor, thereby controlling the input current from the AC power supply in a sine wave form, and the AC voltage from the AC power supply. It has a configuration for converting to a desired DC voltage. In the DC power supply device configured as described above, when feedback control is performed by directly detecting the input current from the AC power supply, the DC component is superimposed on the input current, and the magnitudes of the positive and negative amplitudes become unbalanced. A current sensor called DC-CT is usually used so that the input current can be correctly detected even in the state where the current is detected.

  DC-CT is mainly composed of a Hall element and an operational amplifier, and can detect not only the AC component of the current but also the DC component in principle. However, since DC-CT is generally expensive, when DC-CT is used, it is difficult to configure an inexpensive DC power supply device.

  Further, when DC-CT is used, a current offset error occurs due to an offset voltage of an operational amplifier built in the DC-CT, and therefore it is necessary to design in consideration of this offset error. In the case where the influence of the offset error is unacceptable, it has been necessary to devise such as appropriately correcting the offset amount.

  In addition, in the conventional DC power supply device, a DC power supply device that feedback-controls an input current by using an inexpensive AC-CT (current transformer or AC current transformer) is provided without using an expensive DC-CT. Has been. FIG. 11 is a diagram illustrating a configuration of a conventional DC power supply device using AC-CT. As shown in FIG. 11, the DC power supply device generates a sine wave of an input current from a control rectifier circuit 21 including a plurality of semiconductor switching elements and an AC power supply (AC) and supplies it to a load. And a control signal generating circuit 24 for generating a control signal for controlling the control rectifier circuit 21 so that the output voltage becomes equal to the set DC voltage command value. The current control circuit 23 of the control signal generation circuit 24 includes a DC component removal circuit 22 that removes a DC signal included in a drive signal to a plurality of semiconductor switching elements or a signal in the process of generating the drive signal. In this way, by substantially avoiding the direct current component from being superimposed on the input current, it is possible to detect the input current using an AC-CT (alternating current transformer 3) that cannot detect the direct current component in principle. A DC power supply device having a configuration is known (see, for example, Patent Document 1).

Japanese Patent No. 3863048

  However, in the conventional DC power supply device configured as described above, the positive / negative balance of the AC voltage from the AC power supply, the switching characteristics (delay time, etc.) of the plurality of switching elements, and the voltage during the ON period of the switching elements It is configured to operate on the premise of circuit symmetry that the drops are equal. For this reason, the above-described conventional DC power supply apparatus may not be applicable when the symmetry of the circuit is insufficient with respect to distortion of the voltage waveform of the AC power supply, switching characteristics of the switching element, and the like.

  Also, when the load power is not constant and there are periodic pulsations, such as a motor inverter load whose load torque fluctuates during one rotation, or when the AC power supply voltage or the load suddenly changes Even in the case of a transient, the symmetry of the circuit is broken. Even when the symmetry of the circuit is broken in this way, the input current may be in an unbalanced state, and it is difficult to correctly detect such an input current with AC-CT. For this reason, the above-described conventional DC power supply device has a problem that even if the input current becomes unbalanced, it cannot be detected that the state is unbalanced.

  The present invention solves the above-mentioned problems in the conventional DC power supply apparatus, and requires absolutely no premise such as positive / negative balance in AC power supply voltage, circuit symmetry, and no periodic pulsation in the load. In addition, if an imbalance occurs in the input current from the AC power supply even when the AC power supply voltage or load changes suddenly, a DC power supply device that can reliably detect the unbalanced state is provided. The purpose is to provide.

In order to solve the conventional problem, in the DC power supply device of the present invention, a rectifier circuit that rectifies an AC voltage from an AC power supply,
A switching unit for turning on and off the AC voltage from the AC power source via a reactor;
A smoothing capacitor provided on the output side of the rectifier circuit;
A first current detector for detecting an input current from the AC power supply ;
A control unit that controls the input current to have a current waveform having an amplitude proportional to a predetermined current waveform pattern by using a detection current value of the first current detection unit; ,
A second current detection unit that is provided on the output side of the rectifier circuit and detects a current flowing in a direction in which the smoothing capacitor is charged when the switching unit is off;
The difference information of the detected current values by the first current detection unit and the second current detection unit when the switching unit is off is used.

  The current flowing through the second current detection unit during the OFF period of the switching unit is equal to the absolute value of the input current flowing through the first current detection unit, and the current reading by the first current detection unit and the second current detection unit is performed. The difference between the detected current values is equal to the offset voltage. For this reason, by using the difference information of the absolute value of the detected current value which is the current reading value by the first current detecting unit and the second current detecting unit when the switching unit is off, the unbalanced state of the input current is changed. Can be detected.

  In addition to the same circuit configuration, the DC power supply device of the present invention includes an AC voltage phase detection circuit that detects the phase of the AC voltage from the AC power supply, and the second AC voltage phase is determined at a plurality of predetermined AC voltage phases. The detection current value of the current detection unit is detected, and the difference information of the detection current value of the second current detection unit in two AC voltage phases separated by approximately ½ cycle of the cycle of the AC power supply is used.

  The current flowing through the second current detection unit during the OFF period of the switching unit is equal to the absolute value of the input current flowing through the first current detection unit, and the second current detection unit Unlike the input line of the AC power source through which current flows, it is only necessary to detect current flowing in the same direction at all times. For this reason, even if there is an offset error in the second current detection unit, the current reading value of the second current detection unit at an AC voltage phase separated from each other by a phase corresponding to approximately a half cycle of the AC power supply. In the difference between the detected current values, the offset component is canceled and the unbalanced amount of the input current is shown, so that the unbalanced state of the input current can be detected with high accuracy.

  In the DC power supply device of the present invention, the absolute value of the input current can be detected by the second current detection unit disposed on the output side of the rectifier circuit during the off period of the switching unit, and the unbalanced amount of the input current Therefore, an inexpensive AC-CT (current transformer) can be used for the first current detection unit that detects the input current, and a highly reliable DC power supply device is provided at a low price. be able to.

The figure which showed the structure of DC power supply device of Embodiment 1 which concerns on this invention The circuit diagram which showed the structure of the 1st electric current detection part in the direct-current power supply device of Embodiment 1. Waveform diagram showing an example of an input current waveform and an output voltage waveform of the first current detection unit in the DC power supply device of the first embodiment The circuit diagram which showed another structure of the 1st electric current detection part in the DC power supply device of Embodiment 1 Waveform diagram showing an example of an input current waveform and an output voltage waveform in the first current detection unit shown in FIG. 3A Waveform diagram showing an example of input current waveform when positive and negative are balanced in input current Waveform diagram showing an example of the input current waveform when the input current is not balanced between positive and negative (when imbalance occurs) Waveform diagram showing an example of an output voltage waveform when detected by the first current detection unit having the configuration shown in FIG. 2A in a state where an imbalance occurs in the input current The figure which showed the flow of the input current in the ON period of the switching part The figure which showed the flow of the input current in the off period of the switching part The figure which showed the example of the main circuit which has another structure in the direct-current power supply device of Embodiment 1. The figure which showed the example of the main circuit which has another structure in the direct-current power supply device of Embodiment 1. The figure which showed the example of the main circuit which has another structure in the direct-current power supply device of Embodiment 1. FIG. The figure which showed the structure of the DC power supply device of Embodiment 2 which concerns on this invention The figure which showed the waveform of the input current in the direct-current power supply device of Embodiment 2, and the electric current which flows through a direct-current output line, Comprising: The figure which showed the waveform in which an alternating voltage phase is 90 degree | times, The figure which showed the waveform of the input current in the direct-current power supply device of Embodiment 2, and the electric current which flows through a direct-current output line, Comprising: The figure which showed the waveform with an alternating voltage phase near 270 degree | times The circuit diagram which showed another structural example of the 2nd electric current detection part in the DC power supply device of Embodiment 2. The figure which showed the structure of the conventional DC power supply device using AC-CT

A first invention includes a rectifier circuit that rectifies an AC voltage from an AC power source;
A switching unit for turning on and off the AC voltage from the AC power source via a reactor;
A smoothing capacitor provided on the output side of the rectifier circuit;
A first current detector for detecting an input current from the AC power supply ;
A DC power supply comprising: a control for controlling the input current to have a current waveform having an amplitude proportional to a predetermined current waveform pattern by using a detected current value of the first current detection unit;
A second current detection unit that is provided on the output side of the rectifier circuit and detects a current flowing in a direction in which the smoothing capacitor is charged when the switching unit is off;
The control unit is configured to detect an unbalanced state of the input current using difference information between detected current values of the first current detection unit and the second current detection unit when the switching unit is turned off. Has been.

  In the first invention configured as described above, the current flowing through the second current detection unit is equal to the absolute value of the input current flowing through the first current detection unit in the off period of the switching unit, and Unlike the input line of the AC power source in which current flows in both directions, the current detection unit 2 only needs to detect the current in a line in which current flows intermittently in a single direction. For this reason, in the first invention, it is possible to correctly detect the current using the second current detection unit configured by a shunt resistor, a transformer, and the like. Furthermore, the first current detection unit and the second current detection unit Since the difference in the detected current value, which is the current reading value by the current detection unit, becomes equal to the offset of the first current detection unit, the first current detection unit and the second current detection unit in the off period of the switching unit The unbalanced state of the input current can be detected using the difference information of the absolute value of the detected current value, which is the current reading value. As a result, in the configuration of the first invention, an inexpensive AC-CT can be used for the first current detector.

  In a second aspect of the invention, in particular, in the first aspect of the invention, when the difference between the detection current values of the first current detection unit and the second current detection unit is equal to or greater than a predetermined current value, It is determined that the input current is in an unbalanced state, and the switching unit is stopped. For this reason, the second aspect of the present invention can detect an abnormal condition earlier and stop the supply of the DC voltage to the load even when there is a circuit abnormality or an unexpected AC power supply fluctuation. it can.

  In a third aspect of the invention, in particular, in the first aspect of the invention, the control unit uses the difference between detection current values of the first current detection unit and the second current detection unit to determine the first current detection unit. The detection result is corrected. For this reason, in the third aspect of the invention, the input current can be detected correctly even when the input current is unbalanced due to the effect of offset temporarily. Thus, a balanced current waveform can be maintained.

  In a fourth aspect of the invention, in particular, in any one of the first to third aspects of the invention, the control unit includes an AC voltage phase detection circuit that detects a phase of the AC voltage from the AC power supply, and is determined in advance. Only in a plurality of AC voltage phases, a difference between detection current values of the first current detection unit and the second current detection unit is detected. For this reason, 4th invention becomes the structure which can reduce the calculation load of a control part.

  According to a fifth aspect of the invention, in particular, in the fourth aspect of the invention, the plurality of predetermined AC voltage phases include the approximate peak phase of the AC voltage from the AC power supply, whereby the absolute value of the unbalance amount of the input current is obtained. And the detection accuracy of the offset amount in the input current, that is, the unbalance amount can be increased.

A sixth invention provides a rectifier circuit for rectifying an AC voltage from an AC power source;
A switching unit for turning on and off the AC voltage from the AC power source via a reactor;
A smoothing capacitor provided on the output side of the rectifier circuit;
A first current detector for detecting an input current from the AC power supply ;
In a DC power supply device comprising: a control unit that controls the input current to have a current waveform having an amplitude proportional to a predetermined current waveform pattern;
A second current detection unit that is provided on the output side of the rectifier circuit and detects a current flowing in a direction in which the smoothing capacitor is charged when the switching unit is off;
An AC voltage phase detection circuit for detecting the phase of the AC voltage from the AC power supply,
The control unit detects a detection current value of the second current detection unit in a plurality of predetermined AC voltage phases, and the AC units in two AC voltage phases separated by approximately 1/2 cycle of the cycle of the AC power source. It is configured to detect the unbalanced state of the input current using the difference information of the detected current value of the second current detector.

  In the sixth invention configured as described above, in the difference in the detected current value, which is the current reading value of the second current detection unit, in the AC voltage phase separated by approximately ½ period of the AC power supply period, It shows the amount of current imbalance. For this reason, in the sixth aspect of the invention, by using the difference information of the detected current value, which is the current reading value of the second current detection unit in the AC voltage phase separated by approximately ½ period of the AC power supply period, The imbalance state of the input current can be detected regardless of the detection result of the first current detection unit, and an inexpensive AC-CT can be used for the first current detection unit.

  According to a seventh aspect of the invention, in the sixth aspect of the invention, in the sixth aspect, the control unit may detect the detected current value of the second current detection unit at two AC voltage phases that are approximately ½ cycle apart from the cycle of the AC power supply. When the difference is equal to or greater than a predetermined current value, it is determined that the input current is in an unbalanced state, and the switching unit is stopped. For this reason, in the seventh aspect of the invention, even when there is a circuit abnormality or an unexpected change in the AC power supply, it is detected that there is an abnormal condition sooner and the supply of the DC voltage to the load is stopped. Can do.

  According to an eighth aspect of the invention, in the sixth aspect of the invention, in the sixth aspect, the control unit may detect the detected current value of the second current detection unit at two AC voltage phases separated by approximately ½ period of the AC power supply period. By correcting the detection result of the first current detection unit using the difference, the input current can be detected correctly even when an unbalanced state occurs in the input current due to an offset effect or the like temporarily. it can. For this reason, in the eighth invention, the unbalanced state of the input current can be eliminated and the balanced current waveform can be maintained.

  According to a ninth invention, in particular, in any one of the sixth to eighth inventions, the plurality of predetermined AC voltage phases include an approximate peak phase of an AC voltage from the AC power supply. Since the absolute value of the current unbalance amount increases, the detection accuracy of the offset amount in the input current, that is, the unbalance amount can be increased.

  In a tenth aspect of the invention, in particular, in any one of the first to third or sixth to eighth aspects of the invention, the second current detection unit has a current for charging the smoothing capacitor when the switching unit is off. When the current flows, it is configured to include AC-CT that is resistance-terminated by half-wave rectification on the secondary side so that the direction of current flow on the secondary side is the forward direction. For this reason, in the tenth aspect, circuit loss at the time of current detection can be reduced.

  In the eleventh aspect of the invention, in particular, when a current flows in a direction opposite to the current that charges the smoothing capacitor when the switching unit is off, between the secondary windings of the second current detection unit in the tenth aspect of the invention. The second diode is connected in a direction to short-circuit the voltage induced between the secondary windings. For this reason, in the eleventh aspect of the invention, when the recovery current when the switching unit is turned on is large, the AC-CT in the second current detection unit is prevented from being magnetically saturated, and a more stable circuit operation is realized. be able to.

  Hereinafter, embodiments according to the present invention will be described with reference to the accompanying drawings. In the DC power supply device of the following embodiment, a specific configuration will be described, but the DC power supply device of the present invention is not limited to the specific configuration of the following embodiment, and the same It includes a configuration based on technical ideas. In addition, the present invention controls the current of the input current, such as various electrical devices that once convert an AC voltage from an AC power source into a DC voltage and supply power to a load, such as electrical appliances such as refrigerators, washing machines, and heat pump water heaters. The present invention can be applied to various types of electric equipment including a direct current power supply device.

(Embodiment 1)
FIG. 1 is a diagram showing a configuration of a DC power supply device according to Embodiment 1 of the present invention. As shown in FIG. 1, the DC power supply according to Embodiment 1 includes a reactor 2 connected to one AC line of an AC power supply 1 and a first current detection that detects a current flowing through the reactor 2, that is, an input current. A switching unit 4 which is a bidirectional switching means for short-circuiting / opening (turning on / off) the AC power source 1 via the reactor 3 and the reactor 2, and a rectifier in which an AC input terminal is connected to both ends of the switching unit 4, respectively. A circuit 5, a smoothing capacitor 6 connected between the DC output terminals of the rectifier circuit 5, and a current that flows on the DC output line of the rectifier circuit 5 and flows in the direction in which the smoothing capacitor 6 is charged during the OFF period of the switching unit 4. A second current detection unit 7 for detection is provided.

  The switching unit 4 that is the switching means in the first embodiment may be bidirectional, for example, a circuit in which the output ends of the diode bridge are short-circuited with the IGBT (the input end of the diode bridge is switched). Or the two power MOSFETs connected in series in the opposite direction with the source terminal in common.

  Furthermore, the direct-current power supply device according to the first embodiment includes a control unit 8 composed of a microcomputer or the like, and an alternating-current voltage phase detection circuit 9 connected between both lines of the alternating-current power supply 1. The AC voltage phase detection circuit 9 is composed of, for example, a zero cross detection circuit. The control unit 8 calculates the DC voltage of the smoothing capacitor 6 and the voltage phase calculation unit 8a that estimates and calculates the AC voltage phase of the AC power source 1 from the zero cross point of the AC power source 1 obtained from the AC voltage phase detection circuit 9 and the power cycle. A voltage comparison unit 8b that compares with a DC voltage command value, a voltage control unit 8c that performs proportional-integral compensation based on the result of the voltage comparison unit 8b, and a current command generation unit 8d that generates a current command value are provided. The current command generation unit 8d multiplies the current amplitude value of the substantially sinusoidal reference current waveform corresponding to the AC voltage phase obtained by the voltage phase calculation unit 8a by the output from the voltage control unit 8c, thereby obtaining a current command. Generate a value.

  Further, the control unit 8 determines the offset value of the input current, that is, the uncurrent value based on the difference between the detected current value (reading value) by the first current detecting unit 3 and the detected current value (reading value) by the second current detecting unit 7. An unbalance detection unit 8e for calculating the balance amount is provided. The unbalance detector 8e will be described in detail later. Further, the control unit 8 corrects the detected current value of the first current detection unit 3 by the unbalance amount calculated in the unbalance detection unit 8e, and the instantaneous value of the input current and the current command obtained as a result of the correction. A current comparison unit 8f that compares the values with each other, a current control unit 8g that performs a proportional integral compensation calculation so that the instantaneous value of the input current corrected based on the result of the current comparison unit 8f is equal to the current command value, A carrier wave generation unit 8h that generates a triangular wave carrier wave and a PWM signal generation unit 8i that generates a PWM drive signal of the switching unit 4 by comparing the output of the current control unit 8g with the carrier wave are provided. In the direct-current power supply device according to the first embodiment configured as described above, the switching unit 4 performs a switching operation so that the input current is controlled in a substantially sine wave shape, while the direct-current voltage ( Output voltage) to the load 10.

  In the first embodiment, the control unit 8 is provided with a DC voltage and current detection unit configured by an A / D conversion circuit and the like. 1 is omitted. The first current detection unit 3 includes an A / D conversion circuit that converts an alternating current provided in the control unit 8 into a direct current.

  Hereinafter, an unbalance detection method in the unbalance detection unit 8e and a method for correcting the offset of the first current detection unit 3 will be described.

  FIG. 2A is a circuit diagram showing a configuration of first current detection unit 3 in the DC power supply according to Embodiment 1 of the present invention. FIG. 2B is a waveform diagram showing an example of an input current waveform and an output voltage waveform (Vo) in the first current detection unit 3.

  The configuration of the first current detection unit 3 illustrated in FIG. 2A is an example of a circuit configuration that detects information on both the direction and absolute value of the input current. The configuration illustrated in FIG. 2A is an example of a current detection circuit configured with AC-CT. In the first current detector 3 shown in FIG. 2A, the secondary current detected by AC-CT is offset (Vcc / 2). As shown in FIG. 2B, the first current detection unit 3 includes, in the control unit 8, about the power supply voltage Vcc corresponding to the input range of the A / D conversion circuit that captures the detection voltage of the first current detection unit 3. An output voltage (Vo) proportional to the input current is formed around ½.

  FIG. 3A is a diagram showing another configuration example of the first current detection unit 3 in the DC power supply device according to Embodiment 1 of the present invention. The first current detection unit 3 shown in FIG. 3A has a configuration in which the secondary current detected by AC-CT is full-wave rectified and output. The first current detector 3 configured as shown in FIG. 3A forms the output voltage waveform (Vo) shown in FIG. 3B.

  The configuration in FIG. 3A is an example of a circuit that obtains only the absolute value information of the input current. As shown in FIG. 3B, by using the output voltage based on GND, an A / D conversion circuit in the control unit 8 that operates at the power supply voltage Vcc based on the same GND is used, and the configuration shown in FIG. 2A is used. Compared with the detection method, it is possible to obtain approximately twice the resolution of the A / D conversion circuit.

  FIG. 4A is a waveform diagram showing an example of an input current waveform when the input current is positively and negatively balanced. FIG. 4B is a waveform diagram showing an example of the input current waveform when the positive and negative balance is not achieved in the input current, that is, when an imbalance occurs.

  FIG. 5 shows an output when detected by the first current detector 3 (AC-CT) having the configuration shown in FIG. 2A in the state where the input current is unbalanced as shown in FIG. 4B. It is an example of a voltage waveform. In the output voltage waveform of FIG. 5, in order to make the offset component (DC level) easy to understand, the high frequency component is further cut by LPF (low pass filter) in the output result of the first current detector 3 (AC-CT). The output voltage waveform is shown.

  The input / output characteristics of a general current detection circuit configured by AC-CT as shown in FIG. 2A have HPF (high-pass filter) characteristics determined by the terminating resistance Ro and the excitation inductance, so that the direct current included in the input current The component and the low frequency component are cut. As a result, as shown in FIG. 5, the output voltage has a waveform with a balance between positive and negative. Therefore, it can be understood that it is difficult to detect the unbalanced state of the input current in the configuration of the current detection circuit configured by AC-CT as illustrated in FIG. 2A. The circuit configuration shown in FIG. 3A of the full-wave rectification type is the same when considering the output voltage before turning back, and it is difficult to detect the unbalanced state of the input current.

  6A and 6B show an input current (detection target of the first current detection unit 3) and an output current (smoothing capacitor) flowing through the DC output line of the rectifier circuit 5 in the DC power supply device according to the first embodiment of the present invention. It is a figure which shows the relationship with the positive charge direction of 6. The detection object of the 2nd electric current detection part 7). FIG. 6A is a diagram illustrating the flow of the input current during the ON period (short-circuit period) of the switching unit 4. FIG. 6B is a diagram illustrating the flow of the input current during the off period (open period) of the switching unit 4.

  As shown in FIG. 6B, in the DC power supply device of the first embodiment, the currents flowing through the first current detection unit 3 and the second current detection unit 7 coincide with each other while the switching unit 4 is off.

  In the first embodiment, the second current detection unit 7 is disposed between the negative terminal of the smoothing capacitor 6 and the negative output terminal of the rectifier circuit 5, and the direct-current output voltage GND is provided. Is configured to perform A / D conversion using the control unit 8 driven by the common power source Vcc. When configured in this manner, the second current detection unit 7 can be configured to be very simple by using a current detection resistor (shunt resistor).

  In the unbalance detector 8e, the second current detector 7 can detect a current corresponding to the absolute value of the input current. For this reason, the absolute value of the reading value (detected current value) of the first current detecting unit 3 and the reading value (detected current value) of the second current detecting unit 7 at each timing when the switching unit 4 is turned off. By detecting this difference, the offset value of the input current can be detected each time switching is performed.

  The current comparison unit 8f regards the offset value obtained at each switching as an instantaneous value of the imbalance amount in the input current, and reduces the offset value from the detection current value that is the reading value of the first current detection unit 3. to correct.

  At that time, the unbalance detection unit 8e and the current comparison unit 8f perform correction processing using an LPF calculation (low-pass filter calculation) of the offset value detected as described above as an unbalance amount in order to reduce the influence of noise. May be performed.

  Further, in the current comparison unit 8f, the offset value detected as described above is added to the current command value from the current command generation unit 8d while the reading value (detection current value) of the first current detection unit 3 is left as it is. Thus, the same result can be obtained even if current control is performed by the current control unit 8g.

  As described above, in the DC power supply device of the first embodiment, the unbalance amount is detected by the unbalance detector 8e, and the offset correction is performed on the detected current value by the first current detector 3. Even if an AC-CT that cannot detect a DC component in principle is used as the current detector 3 of 1, the input current from the AC power supply 1 is maintained in a balanced sinusoidal current waveform as shown in FIG. 4A. be able to.

  Further, in the DC power supply device according to the first embodiment, when DC-CT is used instead of AC-CT for the first current detection unit 3, an offset error of DC-CT can be corrected. A more balanced input current waveform can be obtained.

  The configuration of the main circuit of the DC power supply device of the present invention is limited to the circuit configuration shown in FIG. 1 in which the AC power supply 1 is short-circuited by the switching unit 4 via the reactor 2 on the AC input side of the rectifier circuit 5. For example, FIG. 7A, FIG. 7 includes a first current detection unit 3 that directly detects an input current from the AC power source 1 and a second current detection unit 7 that detects a charging current to the smoothing capacitor 6. Needless to say, the same effect can be obtained in other circuit configurations as shown in FIGS. 7B and 7C.

  Further, in the DC power supply device of the first embodiment, when the difference between the absolute values of the detected current values, which are the reading values of the first current detecting unit 3 and the second current detecting unit 7, exceeds a specified value. Since the offset value (unbalance amount) of the input current is higher than expected, it is judged that there is a circuit abnormality or unexpected AC power supply fluctuation, and the switching operation is immediately stopped. It is also possible to do.

(Embodiment 2)
FIG. 8 is a diagram showing the configuration of the DC power supply device according to the second embodiment of the present invention. As shown in FIG. 8, the DC power supply device according to the second embodiment detects the current flowing in the reactor 2 and the reactor 2 connected to one AC line of the AC power source 1, as in the first embodiment. A first current detector 3 that performs switching, a switching unit 4 that is bidirectional switching means for short-circuiting / opening (turning on / off) the AC power supply 1 via the reactor 2, and an AC input terminal at both ends of the switching unit 4 Are connected to each other, the smoothing capacitor 6 connected between the DC output terminals of the rectifying circuit 5, and the smoothing capacitor 6 on the DC output line of the rectifying circuit 5 to charge the smoothing capacitor 6 during the OFF period of the switching unit 4. And a second current detection unit 7 that detects a current flowing in the direction in which the current flows.

  Further, the DC power supply device according to the second embodiment includes a control unit 8 and an AC voltage phase detection circuit 9 as in the first embodiment. The control unit 8 calculates the DC voltage of the smoothing capacitor 6 and the voltage phase calculation unit 8a that estimates and calculates the AC voltage phase of the AC power source 1 from the zero cross point of the AC power source 1 obtained from the AC voltage phase detection circuit 9 and the power cycle. A voltage comparison unit 8b that compares with a DC voltage command value, a voltage control unit 8c that performs proportional-integral compensation based on the result of the voltage comparison unit 8b, and a current command generation unit 8d that generates a current command value are provided. The current command generation unit 8d multiplies the current amplitude value of a substantially sinusoidal reference current waveform corresponding to the AC voltage phase obtained by the voltage phase calculation unit 8a by the output from the voltage control unit 8c, thereby obtaining a current command value. Is generated.

  In addition, the control unit 8 performs current detection with the second current detection unit 7 at each timing of 90 degrees and 270 degrees in which the AC voltage phase obtained by the voltage phase calculation unit 8a corresponds to the peak phase of the AC power supply voltage. And an unbalance detection unit 8e for calculating an offset value of the input current, that is, an unbalance amount, from the difference between the read values (detected current values) of the respective currents. Further, the control unit 8 corrects the reading value (detected current value) of the first current detection unit 3 with the unbalance amount calculated by the unbalance detection unit 8e, and instantaneously corrects the input current obtained as a result of the correction. Current comparator 8f that compares the current value with the current command value, and current control that performs proportional-integral compensation so that the instantaneous value of the input current corrected based on the result of current comparator 8f is equal to the current command value Unit 8g, a carrier wave generation unit 8h that generates a triangular wave carrier wave, and a PWM signal generation unit 8i that generates a PWM drive signal of switching unit 4 by comparing the output of current control unit 8g with the carrier wave. . In the DC power supply device according to the second embodiment configured as described above, the DC voltage controlled according to the DC voltage command is generated while the input current is controlled to be approximately sinusoidal by switching the switching unit 4. Supply to load 10.

  Hereinafter, an unbalance detection method of the unbalance detection unit 8e and a method of correcting the offset of the first current detection unit 3 in the second embodiment will be described.

  FIG. 9A is a diagram illustrating an example of a waveform of an input current and a current flowing through a DC output line in a period in which the instantaneous value of the AC power supply voltage is positive (approximately 90 degrees in phase). As shown in FIG. 9A, the current I2 flowing through the DC output line when the switching unit 4 is OFF is equal to the value of the input current I1, and is basically a positive value. Therefore, the input current value can be easily detected with high accuracy using the shunt resistor.

  FIG. 9B is a diagram illustrating an example of a waveform of an input current and a current flowing through a DC output line in a period in which the instantaneous value of the AC power supply voltage is negative (approximately 270 degrees in phase). As shown in FIG. 9B, the current I2 flowing through the DC output line when the switching unit 4 is OFF is equal to the absolute value of the input current I1, and is basically a positive value. For this reason, the absolute value of the input current value can be detected with high accuracy using the shunt resistor as in the period when the AC power supply voltage shown in FIG. 9A is positive.

  Actually, when the DC component Idc is superimposed on the input current, the difference between the magnitude of the input current at the AC voltage phase of 90 degrees and the magnitude of the input current at the AC voltage phase of 270 degrees is approximately twice the DC component Idc. Is equal to

  The offset component of the current included in the detected current value, which is the detection result of the second current detector 7, is Ioff, and the detected current value (I2 (90)) at the alternating current phase 90 degrees and the detected current at the alternating current phase 270 degrees. Since all the values (I2 (270)) are positive values, the current value detected by the second current detector 7 is a reading value obtained by adding the offset component Ioff to both. For this reason, the difference between the detected current values of the second current detection unit 7 at the AC voltage phase of 90 degrees and 270 degrees calculated by the unbalance detection unit 8e is affected by the offset component Ioff being canceled. Rather, it is equal to twice the DC component Idc contained in the input current.

  As described above, in the configuration of the DC power supply device of the second embodiment, the second current detection unit 7 can be used because the offset component is canceled even if the offset error is large. It has the advantage of being able to.

  In the configuration of the DC power supply device of the second embodiment, the configuration in the case where the voltage phase is 90 degrees and 270 degrees has been described. However, the present invention is not limited to such a configuration, and the AC voltage phase The same result is obtained in the configuration in which the difference between the absolute values of the input currents is detected at timings that are 180 degrees apart from each other.

  In the direct-current power supply device according to the second embodiment of the present invention, the absolute value of the input current separated by approximately 180 degrees (corresponding to approximately one-half power cycle) for each power cycle of the AC power source 1. By detecting the difference by the second current detector 7, it is possible to reliably detect that the input current is in an unbalanced state with a simple configuration.

  In the DC power supply device according to the second embodiment, a configuration in which the control unit 8 corrects the detection current value of the first current detection unit 3 using the unbalance amount of the input current, as in the first embodiment described above. Therefore, AC-CT can be used for the first current detection unit 3.

  Note that the DC power supply device according to the second embodiment immediately determines that there is a circuit abnormality or an unexpected AC power supply fluctuation when the offset value (unbalance amount) of the input current exceeds a specified value. The switching operation may be stopped.

  Further, in the DC power supply device according to the second embodiment, the AC voltage phase timing to be detected is not limited to one set (90 degrees and 270 degrees) in one cycle of the AC power supply 1 as described above, and the necessary detection accuracy is achieved. Accordingly, in order to improve the detection accuracy, it may be performed in a combination of a plurality of phases (for example, a combination of 45 degrees and 135 degrees, 120 degrees and 300 degrees, etc.) during one cycle of the AC power supply 1. You may employ | adopt those results on average. However, by setting 90 ° and 270 °, which are the peak phases of the AC voltage of the AC power supply 1, as one of the detection timings, the absolute value of the unbalance amount of the input current is increased, and the detection is facilitated. .

  In general, in the case of converting an AC voltage to a DC voltage, the PWM duty ratio is the lowest in the vicinity of the voltage phase of 90 degrees and 270 degrees, and the off period becomes longer.

  In the correction method in the DC power supply device of the second embodiment, since the input current read value (detected current value) is corrected using the current flowing during the OFF period of the switching unit 4, the voltage phase in which the OFF period becomes longer. The detection at 90 degrees and 270 degrees has an effect that the timing is shifted and the risk of erroneously detecting the current during the ON period is lowered, and the influence of the detection timing shift is less likely to occur.

  It should be noted that the current detection operation and the control operation for correcting the offset value are performed only at a plurality of AC voltage phase timings separated from each other by a half cycle of a predetermined power cycle shown in the DC power supply device of the second embodiment. The present invention may be applied to the DC power supply device having the configuration of the first embodiment.

  Thus, by performing the control operation for performing the current detection operation and the correction of the second embodiment on the DC power supply device of the first embodiment, the calculation load of the control unit 8 is reduced, and further, the embodiment configured as described above. In the direct-current power supply device of the first embodiment, by performing current detection particularly at the phases of 90 degrees and 270 degrees, the influence due to the shift of the detection timing is less likely to occur, and the same effect as in the second embodiment can be obtained.

  FIG. 10 is a circuit diagram showing another configuration example of the second current detection unit 7 in the DC power supply device of the second embodiment.

  As shown in FIG. 10, in the second current detection unit 7, the AC-CT secondary winding is connected to a half-wave rectifier circuit formed of a diode D1 and a resistor Ro. The termination is connected to GND. Therefore, the second current detection unit 7 causes the secondary side to be half-waved so that the direction in which the current flows to the secondary side becomes the forward direction when the current for charging the smoothing capacitor 6 flows when the switching unit 4 is off. It is composed of AC-CT which is rectified and terminated with resistance. The second current detection unit 7 is configured to detect the voltage across the resistor Ro as a GND reference. In the case of the second current detector 7 configured in this way, the voltage drop value is smaller than that in the case of the shunt resistor, so that the circuit loss at the time of current detection can be reduced.

  In addition, by using AC-CT as the second current detection unit 7, even when the current detection line and the control unit 8 have different potentials, a signal can be transmitted without any problem. The second current detector 7 configured in this way can be disposed between the positive output terminal of the rectifier circuit 5 and the positive terminal of the smoothing capacitor 6, and the second current detector 7. As a result, it becomes easy to perform current detection using the control unit 8 that operates with reference to GND potentials of different potentials of the current detection line.

Further, when the recovery current that flows in a short time immediately after the switching unit 4 is turned on flows in the primary winding, the rectifier circuit 5 is configured by connecting the diode D2 in the direction in which the short-circuit current flows on the secondary winding side. Even when it is necessary to consider the recovery current of the diode to be operated, the AC-CT in the second current detection unit 7 can be stably operated without being magnetically saturated.
The second current detection unit 7 shown in FIG. 10 can be used as the second current detection unit 7 in the above-described first embodiment, and has the same effect.

  As described above, the DC power supply device according to the present invention can be controlled from the AC power supply regardless of the state of the AC power supply or the load even when the input current is detected and the current control is performed using the inexpensive AC-CT. It is possible to reliably detect when the input current is in an unbalanced state. Therefore, the present invention converts the alternating voltage from the alternating current power source into a direct current voltage and supplies the load with power, for example, direct current control for input current of electric appliances such as refrigerators, washing machines, heat pump water heaters, etc. It can be applied as an application to various electric devices equipped with a power supply device.

DESCRIPTION OF SYMBOLS 1 AC power supply 2 Reactor 3 1st electric current detection part 4 Switching part 5 Rectifier circuit 6 Smoothing capacitor 7 2nd electric current detection part 8 Control part 8a Voltage phase calculating part 8e Unbalance detection part 9 AC voltage phase detection circuit

Claims (11)

A rectifier circuit for rectifying an AC voltage from an AC power source;
A switching unit for turning on and off the AC voltage from the AC power source via a reactor;
A smoothing capacitor provided on the output side of the rectifier circuit;
A first current detector for detecting an input current from the AC power supply ;
A control unit that controls the input current to have a current waveform having an amplitude proportional to a predetermined current waveform pattern by using a detection current value of the first current detection unit; ,
A second current detection unit that is provided on the output side of the rectifier circuit and detects a current flowing in a direction in which the smoothing capacitor is charged when the switching unit is off;
The control unit is configured to detect an unbalanced state of the input current using difference information between detected current values of the first current detection unit and the second current detection unit when the switching unit is turned off. DC power supply.   The control unit determines that the input current is in an unbalanced state when a difference between detection current values of the first current detection unit and the second current detection unit is equal to or greater than a predetermined current value, and the switching The DC power supply device according to claim 1, configured to stop the unit.   The control unit is configured to correct a detection result of the first current detection unit using a difference between detection current values of the first current detection unit and the second current detection unit. The direct current power supply device described in 1.   The control unit includes an AC voltage phase detection circuit that detects a phase of an AC voltage from the AC power supply, and the first current detection unit and the second current detection unit only in a plurality of predetermined AC voltage phases. The DC power supply device according to any one of claims 1 to 3, configured to detect a difference between detection current values of the current detection unit.   5. The DC power supply device according to claim 4, wherein the plurality of predetermined AC voltage phases include an approximate peak phase of an AC voltage from the AC power supply. A rectifier circuit for rectifying an AC voltage from an AC power source;
A switching unit for turning on and off the AC voltage from the AC power source via a reactor;
A smoothing capacitor provided on the output side of the rectifier circuit;
A first current detector for detecting an input current from the AC power supply ;
In a DC power supply device comprising: a control unit that controls the input current to have a current waveform having an amplitude proportional to a predetermined current waveform pattern;
A second current detection unit that is provided on the output side of the rectifier circuit and detects a current flowing in a direction in which the smoothing capacitor is charged when the switching unit is off;
An AC voltage phase detection circuit for detecting the phase of the AC voltage from the AC power supply,
The control unit detects a detection current value of the second current detection unit in a plurality of predetermined AC voltage phases, and the AC units in two AC voltage phases separated by approximately 1/2 cycle of the cycle of the AC power source. A DC power supply device configured to detect an unbalanced state of the input current using difference information of detection current values of a second current detection unit.   When the difference between the detected current values of the second current detection unit at two AC voltage phases separated by approximately ½ period of the AC power supply period is equal to or greater than a predetermined current value, the control unit The DC power supply device according to claim 6, wherein the DC power supply device is configured to determine that the switching unit is in a balanced state and stop the switching unit.   The control unit detects the first current detection unit by using a difference between detection current values of the second current detection unit at two AC voltage phases separated by approximately 1/2 cycle of the cycle of the AC power supply. The DC power supply device according to claim 6, configured to correct the result.   9. The DC power supply device according to claim 6, wherein the plurality of predetermined AC voltage phases are configured to include a substantially peak phase of an AC voltage from the AC power supply.   The second current detection unit performs a half-wave rectification on the secondary side so that a current flowing in the secondary side becomes a forward direction when a current for charging the smoothing capacitor flows when the switching unit is turned off. The DC power supply device according to any one of claims 1 to 3 and claim 6 to 8, wherein the DC power supply is configured to include an AC-CT terminated with a resistor.   When a current flows between the secondary windings of the second current detection unit in a direction opposite to the current charging the smoothing capacitor when the switching unit is off, a voltage induced between the secondary windings is The DC power supply device according to claim 10, wherein the second diode is connected in a direction of short-circuiting.

Images