CN110521076B - Power supply device - Google Patents
Power supply device Download PDFInfo
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- CN110521076B CN110521076B CN201880026156.3A CN201880026156A CN110521076B CN 110521076 B CN110521076 B CN 110521076B CN 201880026156 A CN201880026156 A CN 201880026156A CN 110521076 B CN110521076 B CN 110521076B
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- capacitor
- rectifier
- discharge resistor
- power
- power supply
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M5/00—Conversion of ac power input into ac power output, e.g. for change of voltage, for change of frequency, for change of number of phases
- H02M5/40—Conversion of ac power input into ac power output, e.g. for change of voltage, for change of frequency, for change of number of phases with intermediate conversion into dc
- H02M5/42—Conversion of ac power input into ac power output, e.g. for change of voltage, for change of frequency, for change of number of phases with intermediate conversion into dc by static converters
- H02M5/44—Conversion of ac power input into ac power output, e.g. for change of voltage, for change of frequency, for change of number of phases with intermediate conversion into dc by static converters using discharge tubes or semiconductor devices to convert the intermediate dc into ac
- H02M5/453—Conversion of ac power input into ac power output, e.g. for change of voltage, for change of frequency, for change of number of phases with intermediate conversion into dc by static converters using discharge tubes or semiconductor devices to convert the intermediate dc into ac using devices of a triode or transistor type requiring continuous application of a control signal
- H02M5/458—Conversion of ac power input into ac power output, e.g. for change of voltage, for change of frequency, for change of number of phases with intermediate conversion into dc by static converters using discharge tubes or semiconductor devices to convert the intermediate dc into ac using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only
- H02M5/4585—Conversion of ac power input into ac power output, e.g. for change of voltage, for change of frequency, for change of number of phases with intermediate conversion into dc by static converters using discharge tubes or semiconductor devices to convert the intermediate dc into ac using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only having a rectifier with controlled elements
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H7/00—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions
- H02H7/10—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions for converters; for rectifiers
- H02H7/12—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions for converters; for rectifiers for static converters or rectifiers
- H02H7/1216—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions for converters; for rectifiers for static converters or rectifiers for AC-AC converters
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M1/00—Details of apparatus for conversion
- H02M1/32—Means for protecting converters other than automatic disconnection
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J50/00—Circuit arrangements or systems for wireless supply or distribution of electric power
- H02J50/10—Circuit arrangements or systems for wireless supply or distribution of electric power using inductive coupling
- H02J50/12—Circuit arrangements or systems for wireless supply or distribution of electric power using inductive coupling of the resonant type
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M1/00—Details of apparatus for conversion
- H02M1/32—Means for protecting converters other than automatic disconnection
- H02M1/322—Means for rapidly discharging a capacitor of the converter for protecting electrical components or for preventing electrical shock
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- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
- H05B6/00—Heating by electric, magnetic or electromagnetic fields
- H05B6/02—Induction heating
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- Engineering & Computer Science (AREA)
- Power Engineering (AREA)
- Inverter Devices (AREA)
Abstract
A power supply apparatus comprising: a rectifier configured to convert AC power supplied from an AC power source into DC power; a smoothing unit configured to smooth the DC power; an inverter configured to convert the DC power smoothed by the smoothing unit into AC power; and an abnormality detection unit configured to detect an abnormality. The smoothing unit includes: a capacitor connected in parallel to an output of the rectifier; a discharge resistor configured to discharge the capacitor; and a switching device connected in series to the discharge resistor. When the abnormality detection unit detects an abnormality, the switching device is closed, and when the switching device is closed, the capacitor is discharged through the discharge resistor.
Description
Technical Field
The present invention relates to a power supply device.
Background
The inverter device of the related art generates DC power from an AC power source, takes AC output from the DC output through a smoothing circuit composed of a reactor and a smoothing capacitor by controlling on/off of switching devices of the inverter circuit, and applies high-frequency AC power to a heating coil for induction heating. In the inverter apparatus, a discharge resistor for discharging the smoothing capacitor with a predetermined discharge time constant is connected in parallel with the smoothing capacitor (see, for example, JP3419641B 2).
When the discharge resistor is connected in parallel with the smoothing capacitor, electric power is always consumed by the discharge resistor. When the resistance value of the discharge resistor is increased to reduce the power consumed by the discharge resistor, the discharge time constant increases, and it takes a long time to discharge the smoothing capacitor. When electric charge remains in the smoothing capacitor, the electric charge may become an obstacle to inspection or repair of the circuit. Therefore, when an abnormality occurs in the device, the smoothing capacitor is required to be quickly discharged (for example, within 10 seconds).
The inverter device of the related art is used for induction heating of a cooking appliance such as a pot and has a small output, and the smoothing capacitor also has a low capacitance. Therefore, although the resistance value of the discharge resistor is increased to increase the discharge time constant, the influence is slight. As an example, when the smoothing capacitor has a capacitance of 9 μ F and the discharge resistor has a resistance value of 240k Ω, the discharge time constant is set to about 2 seconds.
However, in a power supply device having a high output used for heat treatment of steel or welding operation of resistance welded tubes, a smoothing capacitor also has a high capacitance. In particular, a power supply device used for welding a resistance welding pipe is required to have a low ripple, and a smoothing capacitor used for such a power supply device has an extremely high capacitance of several tens of thousands μ F. When the capacitance of the smoothing capacitor is high as the above value, an increase in the resistance value of the discharge resistor significantly increases the discharge time constant. On the other hand, when the resistance value of the discharge resistor is decreased, the amount of electric power consumed by the discharge resistor increases. Further, a plurality of resistors may be required in the relationship between the power consumption and the rating of the resistor. In this case, the manufacturing cost and the operating cost of the power supply device may increase, while the size of the power supply device increases.
Disclosure of Invention
An illustrative aspect of the present invention provides a power supply device capable of quickly discharging a capacitor included in a smoothing unit in an abnormal situation and reducing loss at a normal time.
According to an illustrative aspect of the invention, a power supply apparatus includes: a rectifier configured to convert AC power supplied from an AC power source into DC power; a smoothing unit configured to smooth the DC power including the ripple output from the rectifier; an inverter configured to convert the DC power smoothed by the smoothing unit into AC power; a case in which the rectifier, the smoothing unit, and the inverter are accommodated; and an abnormality detection unit configured to detect an abnormality of at least one of the rectifier, the inverter, and the housing. The smoothing unit includes: at least one capacitor connected in parallel to the output of the rectifier; a first discharge resistor configured to discharge the capacitor; and a switching device connected in series to the first discharge resistor. The abnormality detection unit closes the switching device when the abnormality detection unit detects an abnormality, and the capacitor is discharged through the first discharge resistor when the switching device is closed.
Drawings
Fig. 1 is a block diagram illustrating a power supply apparatus according to an embodiment.
Fig. 2 is a circuit diagram illustrating a smoothing unit of the power supply apparatus of fig. 1.
Fig. 3 is a circuit diagram illustrating a modification of the smoothing unit of the power supply device of fig. 1.
Fig. 4 is a block diagram illustrating a power supply apparatus according to another embodiment.
Fig. 5 is a circuit diagram illustrating a control unit of the power supply apparatus of fig. 4.
Fig. 6 is a circuit diagram illustrating a control unit of the power supply apparatus of fig. 4.
Detailed Description
Fig. 1 illustrates one example of a power supply device according to an embodiment. Fig. 2 illustrates an example of a smoothing unit.
The power supply device 1 includes: a rectifier 3 for converting AC power supplied from the AC power supply 2 into DC power; a smoothing unit 4 for smoothing the DC power having a ripple and output from the rectifier 3; and an inverter 5 for converting the DC power smoothed by the smoothing unit 4 into AC power. In the present embodiment, the power supply apparatus 1 further includes a breaker 6 for cutting off the supply of electric power to the rectifier 3 when an overcurrent flows from the AC power supply 2 to the rectifier 3, and the rectifier 3, the smoothing unit 4, the inverter 5, and the breaker 6 are accommodated in the casing 7.
The rectifier 3 may perform rectification using a diode bridge or variably rectify the smoothed DC voltage using a semiconductor device such as a thyristor capable of controlling conduction based on an external signal. When using a semiconductor device, the conduction of the semiconductor device is controlled by the control unit 8.
The inverter 5 includes a full bridge circuit including, for example, four power semiconductor devices each capable of switching operation, and generates high-frequency AC power by predetermined switching operations of the four power semiconductor devices. The high frequency output can be set to a three-phase output by six power semiconductor devices. The switching operation of the power semiconductor device is controlled by the control unit 8.
At this time, as the power semiconductor device, various types of power semiconductor devices capable of switching operations, such as an Insulated Gate Bipolar Transistor (IGBT) and a Metal Oxide Semiconductor Field Effect Transistor (MOSFET), can be used, and silicon (Si) or silicon carbide (SiC) can be used as a semiconductor material.
A load 9 including a heating coil is connected to an output of the inverter 5, and high-frequency AC power generated by the inverter 5 is applied to the heating coil. Further, the heating target is inductively heated by the heating coil. The heating target and the heating purpose are not particularly limited, and a heat treatment (quenching or the like) for a steel material and a welding operation for an electric resistance welded pipe can be exemplified.
As shown in fig. 2, the smoothing unit 4 includes a capacitor 10, a reactor 11, a first discharge resistor 12, a second discharge resistor 13, and a switching device 14.
The capacitor 10 is connected in parallel to the output of the rectifier 3, and eliminates or reduces a ripple included in the DC power of the rectifier 3. The capacitance of the capacitor 10 is appropriately set according to the output of the power supply device 1. For example, when the output of the power supply apparatus 1 is set to about 300kW, the capacitance of the capacitor 10 can be set to about 20000 μ F (however, the capacitance is a value of the power supply apparatus having a very low ripple). At this time, an electrolytic capacitor whose capacitance can be easily increased may be used as the capacitor 10, but the capacitor 10 is not limited to the electrolytic capacitor.
In the present embodiment, the reactor 11 is interposed between the positive electrode of the output of the rectifier 3 and the terminal of the capacitor 10 connected to the positive electrode side. The reactor 11 forms a low-pass filter together with the capacitor 10, and improves ripple cancellation capability.
The first discharge resistor 12 and the switching device 14 are connected in series with each other, and the first discharge resistor 12 and the switching device 14 connected in series are connected in parallel to the output of the rectifier 3. The switching device 14 can be opened/closed by the control unit 8 based on an external signal. When the switching device 14 is closed (conductive), the capacitor 10 is discharged through the first discharge resistor 12 and the switching device 14.
An element having a mechanical contact such as a magnetic switch that is opened/closed by attracting a moving iron using an electromagnet, or a semiconductor device such as a thyristor is used as the switching device 14. However, a semiconductor device having a long lifetime may be preferably used instead of an element having a mechanical contact.
The second discharge resistor 13 is connected in parallel to the first discharge resistor 12, and the capacitor 10 is always discharged through the second discharge resistor 13. The second discharge resistor 13 has a larger resistance value than the first discharge resistor 12. For example, the resistance value of the first discharge resistor 12 is several hundred Ω, and the resistance value of the second discharge resistor 13 ranges from several tens of k Ω to several hundreds of k Ω.
The breaker 6 cuts off the power supply to the rectifier 3 when an overcurrent flows from the AC power supply 2 to the rectifier 3, and transmits an abnormality signal indicating an abnormality of the rectifier 3 to the control unit 8 when the power supply to the rectifier 3 is cut off.
For example, the control unit 8 includes a processor as a main portion. The control unit 8 controls the switching operation of the power semiconductor devices of the inverter 5, and controls the conduction of semiconductor devices such as thyristors when the semiconductor devices are used in the rectifier 3. When an abnormal signal is input from the circuit breaker 6, the control unit 8 closes the switching device 14.
When the switching device 14 is closed, the capacitor 10 is discharged through the first discharge resistor 12 in addition to the second discharge resistor 13. The resistance value (for example, several hundred Ω) of the first discharge resistor 12 is smaller than the resistance value (for example, several tens of k Ω to several hundreds of k Ω) of the second discharge resistor 13, and most of the electric charges stored in the capacitor 10 flow to the first discharge resistor 12. Since the discharge resistor has a small resistance value with respect to the inter-terminal voltage of the capacitor 10, the current flowing through the discharge resistor increases. When the circuit breaker 6 and the control unit 8 detect an abnormality of the rectifier 3, the capacitor 10 can be quickly discharged through the first discharge resistor 12 having a small resistance value. For example, when the capacitor 10 has a capacitance of 20000 μ F and the first discharge resistor 12 has a resistance value of 300 Ω, the discharge time constant is set to about six seconds.
From the viewpoint of stability against heat generation, the always-on resistor operates at about 1/4 of the rated power. However, when the switching device 14 is closed in an abnormal situation, the charge stored in the capacitor 10 flows only to the first discharge resistor 12, and heat generation associated with the conduction of the first discharge resistor 12 is temporary. Therefore, the first discharge resistor 12 can operate at or near the upper limit of the rated power. Therefore, the number of resistors constituting the first discharge resistor 12 can be reduced, the manufacturing cost of the power supply device 1 can be reduced, and the size of the power supply device 1 can be reduced. For example, when the output voltage of the AC power supply 2 is 440V and the rectifier 3 rectifies by the diode bridge, the output voltage of the rectifier 3 becomes about 600V. Also, when the resistance value of the first discharge resistor 12 is 300 Ω, the current flowing through the first discharge resistor 12 is 2A at the maximum, and the power consumption of the first discharge resistor 12 is 1200W at the maximum. In this case, when a resistor having a higher power rating, such as an enamel resistor, is used, the first discharge resistor 12 can be implemented by one resistor. This is because the first discharge resistor 12 is used only during discharge and is used in a method in which the usage rate is low.
When the power supply device 1 operates normally and stops at a normal time, that is, when no abnormality is detected, electricity is not conducted to the first discharge resistor 12, and electric power is not consumed by the first discharge resistor 12. Therefore, the operating cost of the power supply device can be reduced.
In order to rapidly discharge the capacitor 10 in the event of an abnormality, the second discharge resistor 13 may be omitted. However, it is preferable that the capacitor 10 is always discharged through the second discharge resistor 13 when the second discharge resistor 13 is provided and the power supply device 1 is normally operated and stopped. For example, when the charging of the capacitor 10 is started, the inter-terminal voltage of the capacitor 10 may temporarily rise in a transient state. However, since the capacitor 10 is discharged through the second discharge resistor 13, it is possible to suppress application of an excessive voltage to the inverter 5, and to protect the power semiconductor device of the inverter 5.
For example, since the resistance value of the second discharge resistor 13 is much higher than that of the first discharge resistor 12, ranging from several tens of k Ω to several hundreds of k Ω, the current flowing through the second discharge resistor 13 is extremely low, for example, ranging from several mA to several tens of mA. Therefore, although the second discharge resistor 13 always consumes power, the power consumption is low.
Fig. 3 illustrates a modification of the smoothing unit 4.
In the example shown in fig. 3, the smoothing unit 4 includes a first capacitor 21 and a second capacitor 22 as capacitors connected in parallel to the output of the rectifier 3. The first capacitor 21 is connected through the diode 20 and the second capacitor 22 is directly connected. The smoothing unit 4 further includes a first discharge resistor 23, a second discharge resistor 24, a third discharge resistor 25, and a switching device 26.
The first discharge resistor 23 and the switching device 26 are connected in series with each other, and the first discharge resistor 23 and the switching device 26 connected in series are connected in parallel to the first capacitor 21. The switching device 26 can be opened/closed by the control unit 8 based on an external signal.
The second discharge resistor 24 is connected in parallel to the first discharge resistor 23, and the first capacitor 21 is always discharged through the second discharge resistor 24. In order to reduce the power consumption of the second discharge resistor 24, the resistance value of the second discharge resistor 24 may be set to a larger resistance value than the first discharge resistor 23. For example, the resistance value of the first discharge resistor 23 is several hundred Ω, and the resistance value of the second discharge resistor 24 ranges from several tens of k Ω to several hundreds of k Ω.
The third discharge resistor 25 is connected in parallel to the second capacitor 22, and the second capacitor 22 is always discharged through the third discharge resistor 25. In order to reduce the power consumption of the third discharge resistor 25, the resistance value of the third discharge resistor 25 may be set to a larger resistance value than the first discharge resistor 23. For example, the resistance value of the first discharge resistor 23 is several hundred Ω, and the resistance value of the third discharge resistor 25 ranges from several tens of k Ω to several hundreds of k Ω.
When the voltage between the terminals of the first capacitor 21 is lower than the voltage between the terminals of the second capacitor 22, the first capacitor 21 connected in parallel to the output of the rectifier 3 through the diode 20 is discharged. Therefore, the ripple contained in the output of the rectifier 3 is substantially eliminated or reduced by the second capacitor 22. As with the capacitor 10 of the smoothing unit 4 shown in fig. 2, the second capacitor 22 is always discharged through the third discharge resistor 25, which makes it possible to suppress the inter-terminal voltage of the second capacitor 22 from rising in a transient state while protecting the power semiconductor devices of the inverter 5. The first capacitor 21 forms a transient voltage suppression circuit together with the diode 20 and the second discharge resistor 24, and also suppresses a rise in the inter-terminal voltage of the second capacitor 22 in a transient state. Since the inter-terminal voltage of the second capacitor 22 is suppressed from rising in the transient state by the transient voltage suppression circuit, the third discharge resistor 25 may be omitted.
Preferably, the first capacitor 21 may have a lower capacitance than the second capacitor 22, and for example, a film capacitor having a longer lifetime than an electrolytic capacitor may be suitably used as the first capacitor 21 having a lower capacitance.
In the embodiment shown in fig. 3, when an overcurrent flows from the AC power source 2 to the rectifier 3, the circuit breaker 6 cuts off the power supply to the rectifier 3 and transmits an abnormal signal from the circuit breaker 6 to the control unit 8, so that the switching device 26 is closed by the control unit 8. When the switching device 26 is closed, the first capacitor 21 is first discharged through the first discharge resistor 23, except for the second discharge resistor 24. The resistance value (for example, several hundred Ω) of the first discharge resistor 23 is smaller than the resistance value (for example, several tens k Ω to several hundreds k Ω) of the second discharge resistor 24, and most of the electric charges stored in the first capacitor 21 flow to the first discharge resistor 23, so that the first capacitor 21 is rapidly discharged through the first discharge resistor 23. When the first capacitor 21 is discharged so that the inter-terminal voltage of the first capacitor 21 becomes lower than the inter-terminal voltage of the second capacitor 22, the second capacitor 22 is also rapidly discharged through the first discharge resistor 23. For example, when the first capacitor 21 has a capacitance of 7000 μ F, the second capacitor 22 has a capacitance of 20000 μ F, and the first discharge resistor 23 has a resistance value of 300 Ω, the discharge time constant is set to about eight seconds.
In the present invention, it has been described that an abnormality is determined to occur in the power supply apparatus 1 when an overcurrent flows from the AC power supply 2 to the rectifier 3, and the abnormality of the rectifier 3 is detected by the circuit breaker 6 and the control unit 8. However, the opening of the door of the casing 7 may be detected as an abnormality of the power supply device 1. For example, a door opening detection unit including an appropriate switch or sensor is installed at the door or door frame of the housing 7, and is turned on or off according to the door opening of the housing 7, and the door opening of the housing 7 is detected by the control unit 8 based on the on/off state of the door opening detection unit. When the opening of the door of the case 7 is detected, the switching device 14 in the smoothing unit 4 shown in fig. 2 is closed by the control unit 8, and the capacitor 10 is rapidly discharged through the first discharge resistor 12. Further, the switching device 26 in the smoothing unit 4 shown in fig. 3 is closed by the control unit 8, and the first capacitor 21 and the second capacitor 22 are rapidly discharged through the first discharge resistor 23.
As for the abnormality of the power supply device 1, an abnormality of the inverter 5 can be detected. Abnormality of the inverter 5 and a detection method thereof will be described with reference to fig. 4 to 6. Further, the same elements as those of the above-described power supply device 1 are denoted by the same reference numerals, and detailed description thereof will be omitted or simplified.
The control unit 8 includes a phase-locked loop circuit (hereinafter, simply referred to as "PLL circuit") 30 and an abnormality detection circuit 31. The PLL circuit 30 controls the frequency of the AC power output from the inverter 5 so that the frequency of the AC power becomes the resonance frequency of the load 9 connected to the inverter 5. The inverter 5 includes a converter 32 for detecting a current I1 applied to the load 9 and a transformer 33 for detecting a voltage V1 applied to the load 9.
As shown in fig. 5, the PLL circuit 30 includes a phase comparison circuit 40, an analog adder/subtractor 41, a voltage controlled oscillator 42, and a control signal circuit 43. The phase comparison circuit 40 detects the phase of the current I1 detected by the current transformer 32 and the phase of the voltage V1 detected by the transformer 33. The analog adder/subtractor 41 increases/decreases a preset frequency setting value according to the phase detected by the phase comparison circuit 40. The voltage controlled oscillator 42 outputs a signal at a frequency corresponding to the voltage output from the analog adder/subtractor 41. The control signal circuit 43 transmits control signals to the control terminals g1 to g4 of the power semiconductor devices M1 to M4 of the inverter 5 according to the frequency of the signal output from the voltage controlled oscillator 42.
The PLL circuit 30 controls the operating frequency of the inverter 5 to eliminate a phase shift between the current I1 supplied to the load 9 and the voltage V1 applied to the load 9, and the frequency of the AC power output from the inverter 5 coincides with the resonance frequency of the load 9 including the inductance component L and the capacitance component C. Therefore, the efficiency of the power supply device 101 can be improved.
However, when a part of the circuit on the load 9 side is short-circuited or an abnormality such as an open circuit occurs, the impedance of the load 9 changes rapidly and the resonance frequency changes significantly. Then, the PLL circuit 30 adjusts the operating frequency of the inverter 5 so that the operating frequency follows the resonance frequency of the load 9. In the transient state, a high current or voltage may be instantaneously generated in the inverter 5 and damage the power semiconductor devices M1 to M4. In particular, when the phase of the current I1 is advanced to the phase of the voltage V1 due to a change in the impedance of the load 9, a high surge voltage may be generated, and the power semiconductor devices M1 to M4 may be damaged due to the surge voltage. The abnormality detection circuit 31 constitutes a phase shift detection unit together with the current transformer 32 and the transformer 33, and detects a phase shift between the current I1 detected by the current transformer 32 and the voltage V1 detected by the transformer 33.
The current I1 detected by the current transformer 32 and the voltage V1 detected by the transformer 33 are input to the abnormality detection circuit 31. As shown in fig. 6, the abnormality detection circuit 31 includes a waveform shaper 50, a waveform shaper 51, a data flip-flop 52, a flip-flop 53, a comparator 54, and an inversion unit 55. The waveform shaper 50 shapes the waveform of the input voltage V1 into a predetermined square wave. The waveform shaper 51 adjusts the waveform of the input current I1 to a predetermined square wave. The data flip-flop 52 functions as a phase shift detection unit that detects a phase shift between the voltage V1 and the current I1. Flip-flop 53 serves as a latch that holds the output of data flip-flop 52. The comparator 54 detects whether the magnitude of the current I1 has reached the reference value. The inverting unit 55 inverts the output signal of the comparator 54.
The waveform shaper 50 includes: a resistor 50A, the resistor 50A having a DC resistance value corresponding to the voltage input to the data flip-flop 52; and a capacitor 50B for cutting off unnecessary harmonic components contained in the waveform of the voltage V1. The waveform shaper 51 includes: a resistor 51A, the resistor 51A having a DC resistance value corresponding to the voltage input to the data flip-flop 52; and a capacitor 51B for cutting off unnecessary harmonic components contained in the waveform of the current I1, like the waveform shaper 50.
The data flip-flop 52 includes a clock input port CL for receiving a clock signal, a data input port D for receiving a data signal, a set input port S for receiving a set signal, a reset input port R for receiving a reset signal, and a set signal port Q for transmitting the set signal in a set state. When the clock signal and the data signal are simultaneously input, the data flip-flop 52 is set to the set state, and the set signal is transmitted from the set signal port Q.
The comparator 54 is for comparing magnitudes of AC signals respectively input to the two input ports. One input port of comparator 54 receives an AC signal representative of the value of current I1 applied to load 9. The other input port of the comparator 54 receives an AC signal, which is obtained by dividing a predetermined AC voltage V2 by the variable resistor 56, as a preset reference value. When the current I1 becomes higher than the reference value, the comparator 54 outputs a normal operation signal. The normal operation signal is inverted by the inversion unit 55 and sent to the reset input port R of the data flip-flop 52. The comparator 54, the inverting unit 55, and the variable resistor 56 form a mask unit 57, and the mask unit 57 continuously outputs the reset signal to the data flip-flop 52 until the value of the current I1 becomes higher than the reference value.
In the above-described configuration, until the operation of the power supply apparatus 1 reaches the normal state after the power supply apparatus 1 has been activated, or specifically until the operating frequency of the inverter 5 coincides with the resonance frequency of the load 9 and the current I1 supplied to the load 9 becomes higher than the reference value, the mask unit 57 continuously outputs the reset signal to the data flip-flop 52, and suspends the phase shift detection operation of the abnormality detection circuit 31. Therefore, it is possible to eliminate a malfunction that may occur when the power supply device 1, in which the current I1 supplied to the load 9 is unstable and the phase does not coincide with the voltage, is forcibly stopped immediately after activation. Further, when the operation of the power supply device 1 reaches the normal state, the phase shift detection operation of the abnormality detection circuit 31 is started.
When the resonance frequency of the load 9 coincides with the operation frequency of the inverter 5 and the phases of the voltage V1 and the current I1 coincide with each other, the data flip-flop 52 is maintained in the reset state and does not transit to the set state, the set signal is not transmitted from the set signal port Q, and the operation of the power supply device 1 continues without change.
On the other hand, when an abnormality occurs in the load 9 and the resonance frequency of the load 9 deviates from the operation frequency of the inverter 5, the phase of the voltage V1 and the phase of the current I1 do not coincide with each other, and the phase shift becomes an abnormality of the inverter 5. In this state, the data flip-flop 52 transitions to the set state, and the set signal is transmitted from the set signal port Q. The set signal is input to the PLL circuit 30 through the flip-flop 53 as an abnormality signal indicating an abnormality of the inverter 5.
The PLL circuit 30 receiving the abnormal signal appropriately turns off the power semiconductor devices M1 to M4 and stops the supply of power to the load 9, and thereby protects the power semiconductor devices M1 to M4. The exception signal is continuously output until the flip-flop 53 is reset. The switching device 4 in the smoothing unit 4 shown in fig. 2 is closed by the control unit 8, the control unit 8 transmits and receives an abnormality signal between the PLL circuit 30 and the abnormality detection circuit 31 inside thereof, and the capacitor 10 is rapidly discharged through the first discharge resistor 12. Further, the switching device 26 in the smoothing unit 4 shown in fig. 3 is closed, and the first capacitor 21 and the second capacitor 22 are rapidly discharged through the first discharge resistor 23.
According to the abnormality detection method of the inverter 5 described above, it is possible to quickly detect an abnormality of the inverter 5 caused by a change in the resonant frequency of the load 9 from the phase shift between the current I1 and the voltage V1. Thus, it is possible to reliably detect an abnormality of the inverter 5 before the end of the operation of the PLL circuit 30 that controls the operating frequency of the inverter 5 to follow the resonance frequency of the load 9. Further, when an abnormality of the inverter 5 is detected, it is possible to appropriately turn off the power semiconductor devices M1 to M4 of the inverter 5, and thereby prevent damage of the power semiconductor devices M1 to M4 in advance.
The abnormality detection circuit 31 for detecting the phase shift between the current I1 and the voltage V1 is set to the set state with the data signal input simultaneously with the clock signal, and the data flip-flop 52 transmits the set output as a signal in the set state. Only when the phase of the current I1 deviates from the voltage V1, a set signal (abnormal signal) is output from the data flip-flop 52. Therefore, the phase shift between the current I1 and the voltage V1 can be detected by a simple circuit configuration.
The abnormality detection circuit 31 includes a mask unit 57, and the mask unit 57 compares the current value of the current I1 supplied to the load 9 with a preset reference value, and continuously outputs a reset signal to the data flip-flop 52 until the value of the current I1 becomes higher than the reference value. During activation of the power supply device 1 in which the current I1 is unstable and the phase of the current I1 and the phase of the voltage V1 do not coincide with each other, the phase shift detection operation of the abnormality detection circuit 31 is temporarily suspended, which makes it possible to prevent the power supply device 1 from being forcibly stopped immediately after the power supply device 1 has been activated.
An abnormality detection unit that is constituted by the circuit breaker 6 and the control unit 8 and detects an abnormality of the rectifier 3, an abnormality detection unit that is constituted by the door opening detection unit and the control unit 8 and detects an abnormality of the case 7, and an abnormality detection unit that is constituted by the converter 32, the transformer 33, and the control unit 8 including the abnormality detection circuit 31 and detects an abnormality of the inverter 5 may be used independently or in combination.
This application claims priority to japanese patent application No.2017-185140, filed on 26.9.2017, the entire contents of which are incorporated herein by reference.
Claims (8)
1. A power supply apparatus comprising:
a rectifier configured to convert AC power supplied from an AC power source into DC power;
a smoothing unit configured to smooth the DC power including a ripple output from the rectifier;
an inverter configured to convert the DC power smoothed by the smoothing unit into AC power;
a case in which the rectifier, the smoothing unit, and the inverter are accommodated; and
an abnormality detection unit configured to detect an abnormality of at least one of the rectifier, the inverter, and the housing,
wherein the smoothing unit includes:
at least one capacitor connected in parallel to the output of the rectifier;
a first discharge resistor configured to discharge the capacitor; and
a switching device connected in series to the first discharge resistor,
wherein the abnormality detection unit closes the switching device when the abnormality detection unit detects an abnormality, and the capacitor is discharged through the first discharge resistor when the switching device is closed,
wherein the smoothing unit includes a first capacitor and a second capacitor as the capacitors, the first capacitor being connected to an output of the rectifier through a diode, the second capacitor being connected in series to the output of the rectifier and having a capacitance larger than that of the first capacitor, and
wherein the first discharge resistor is connected in parallel to the first capacitor.
2. The power supply device according to claim 1, wherein the smoothing unit further includes a second discharge resistor connected in parallel to the first discharge resistor and configured to always discharge the capacitor, and
wherein the second discharge resistor has a resistance value larger than a resistance value of the first discharge resistor.
3. The power supply device according to claim 1, wherein the smoothing unit further includes a third discharge resistor connected in parallel to the second capacitor and configured to always discharge the second capacitor, and
wherein the third discharge resistor has a resistance value larger than a resistance value of the first discharge resistor.
4. The power supply device of claim 1, wherein the switching device has mechanical contacts.
5. The power supply device according to claim 1, wherein the switching device is a semiconductor device.
6. The power supply device according to any one of claims 1 to 5, wherein the abnormality detection unit includes a circuit breaker configured to cut off power supply to the rectifier when an overcurrent flows from the AC power supply to the rectifier, and closes the switching device when the circuit breaker cuts off power supply to the rectifier.
7. A power supply apparatus comprising:
a rectifier configured to convert AC power supplied from an AC power source into DC power;
a smoothing unit configured to smooth the DC power including a ripple output from the rectifier;
an inverter configured to convert the DC power smoothed by the smoothing unit into AC power;
a case in which the rectifier, the smoothing unit, and the inverter are accommodated; and
an abnormality detection unit configured to detect an abnormality of at least one of the rectifier, the inverter, and the housing,
wherein the smoothing unit includes:
at least one capacitor connected in parallel to the output of the rectifier;
a first discharge resistor configured to discharge the capacitor; and
a switching device connected in series to the first discharge resistor,
wherein when the abnormality detection unit detects an abnormality, the abnormality detection unit closes the switching device, and when the switching device is closed, the capacitor is discharged through the first discharge resistor, and
wherein the abnormality detection unit includes a door opening detection unit configured to detect opening of a door when the housing is opened, and the abnormality detection unit closes the opening and closing device when the door opening detection unit detects opening of the door.
8. A power supply apparatus comprising:
a rectifier configured to convert AC power supplied from an AC power source into DC power;
a smoothing unit configured to smooth the DC power including a ripple output from the rectifier;
an inverter configured to convert the DC power smoothed by the smoothing unit into AC power;
a case in which the rectifier, the smoothing unit, and the inverter are accommodated; and
an abnormality detection unit configured to detect an abnormality of at least one of the rectifier, the inverter, and the housing,
wherein the smoothing unit includes:
at least one capacitor connected in parallel to the output of the rectifier;
a first discharge resistor configured to discharge the capacitor; and
a switching device connected in series to the first discharge resistor,
wherein when the abnormality detection unit detects an abnormality, the abnormality detection unit closes the switching device, and when the switching device is closed, the capacitor is discharged through the first discharge resistor, and
wherein the inverter is controlled to have an output frequency corresponding to a resonance frequency of a load connected to the power supply device, and
wherein the abnormality detection unit includes a phase shift detection unit configured to detect a phase shift between an output current and an output voltage of the inverter, and to close the switching device when the phase shift detection unit detects the phase shift.
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2017185140A JP6340463B1 (en) | 2017-09-26 | 2017-09-26 | Power supply |
| JP2017-185140 | 2017-09-26 | ||
| PCT/JP2018/034913 WO2019065472A1 (en) | 2017-09-26 | 2018-09-20 | Power supply apparatus |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN110521076A CN110521076A (en) | 2019-11-29 |
| CN110521076B true CN110521076B (en) | 2022-04-08 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201880026156.3A Active CN110521076B (en) | 2017-09-26 | 2018-09-20 | Power supply device |
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| Country | Link |
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| JP (1) | JP6340463B1 (en) |
| CN (1) | CN110521076B (en) |
| TW (1) | TWI644506B (en) |
| WO (1) | WO2019065472A1 (en) |
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| CN111431389A (en) * | 2020-04-15 | 2020-07-17 | 中国南方电网有限责任公司超高压输电公司广州局 | MMC power module quick discharge circuit |
| EP3920391A1 (en) * | 2020-06-04 | 2021-12-08 | Schaffner EMV AG | Emi filter |
| KR20230162035A (en) * | 2021-04-01 | 2023-11-28 | 도시바 미쓰비시덴키 산교시스템 가부시키가이샤 | power conversion device |
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Also Published As
| Publication number | Publication date |
|---|---|
| CN110521076A (en) | 2019-11-29 |
| TW201916569A (en) | 2019-04-16 |
| JP2019062640A (en) | 2019-04-18 |
| JP6340463B1 (en) | 2018-06-06 |
| TWI644506B (en) | 2018-12-11 |
| WO2019065472A1 (en) | 2019-04-04 |
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