JP3580190B2 - Inverter power supply and method for detecting connection of other power supply between output terminals thereof - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an inverter power supply device that converts a DC voltage to an AC voltage and supplies it to a load, and a method for detecting whether or not another power supply is connected between load connection terminals of the power supply device. It is.
[0002]
[Prior art]
2. Description of the Related Art An inverter power supply is used, for example, in an engine generator (engine generator) using an internal combustion engine as a prime mover to convert a rectified output of the generator into an AC voltage having a constant frequency (usually a commercial frequency). .
[0003]
An inverter power supply device used in this type of power generation device has an energization path for a feedback current, and is provided with n (n is an integer of 2 or more) switches turned on in response to a drive signal. And a bridge type inverter circuit having a lower side respectively, a DC power supply circuit for inputting a DC voltage to the inverter circuit, and a switch of the inverter circuit so that the waveform of the output voltage of the inverter circuit is a PWM modulated AC voltage waveform. And a filter circuit provided between a load connection terminal to which a load is connected and an output terminal of the inverter circuit.
[0004]
In a power generator using the above-described inverter power supply device, an AC voltage output from a multi-pole magnet generator is converted into a constant DC voltage by a rectifier, and the DC voltage is input to an inverter circuit. The control device applies a drive signal to the pair of switches at diagonal positions of the bridge circuit forming the inverter circuit so as to be simultaneously turned on for a desired half cycle of a sine wave, and supplies a drive signal to the switches. Alternatively, by turning on and off the lower switch with a duty ratio proportional to the instantaneous peak value of each sine wave, the inverter circuit generates a PWM-modulated AC voltage. The voltage output from the inverter circuit is converted into a smooth sine wave voltage through a filter circuit, and then applied to a load through a load connection terminal.
[0005]
The sine wave voltage applied to the load is detected by the load voltage detection circuit and fed back to the control device. The control device compares each instantaneous magnitude of the output voltage with each instantaneous value (set value) of the desired sine wave voltage, and when the instantaneous value of the output voltage is lower than the instantaneous value of the desired sine wave voltage, the PWM The duty ratio of the control is increased, and when the instantaneous value of the output voltage becomes higher than the instantaneous value of the desired sine wave voltage, the duty ratio of the PWM control is controlled to be small, so that the desired magnitude between the load connection terminals is obtained. And generate a sinusoidal voltage having
[0006]
The control device also performs overcurrent control for stopping output of a drive signal given to a switch of the inverter circuit when the load current detected by the load current detection circuit exceeds a set value (when overcurrent is detected). . With this overcurrent control, the output of the inverter circuit is stopped when the overcurrent flows, and the switches constituting the inverter circuit are protected.
[0007]
In this type of power supply, by controlling the inverter circuit, a DC voltage output from the rectifier can be converted into an AC voltage having an arbitrary frequency, so that the load connection can be performed irrespective of the rotation speed of the generator. A voltage having a desired frequency can be obtained at the terminal.
[0008]
[Problems to be solved by the invention]
When the capacity of the load is large, it may be necessary to operate the inverter power supply in parallel with another power supply (similar inverter power supply or another AC power supply). When the inverter power supply is operated in parallel with the other power supply, a corresponding output terminal of the other power supply is connected to the load connection terminal of the power supply, and power is simultaneously supplied from both power supplies to the load. In this case, the voltages generated by the two power supplies must have the same frequency, magnitude, and phase. If the frequencies and phases of the voltages generated by the two power supplies are different from each other, the load current flowing from one power supply flows into the other power supply, and an overcurrent flows. When an overcurrent flows, the output of the inverter power supply stops due to the overcurrent control.
[0009]
When an overcurrent flows due to an overload condition or a short circuit accident that has occurred on the load side, it is necessary to immediately perform overcurrent control to stop the output of the inverter power supply. Is connected, it is necessary to immediately perform control for matching the phase of the output voltage of the inverter power supply device with the phase of the voltage supplied from another power supply.
[0010]
In a conventional inverter power supply device used for an engine power generation device or the like, when an overcurrent is detected, it is regarded that another power supply is connected between the load connection terminals, and the inverter power supply device is used. The control for matching the phase of the output voltage to the phase of the voltage supplied from another power source is performed, and then the overcurrent control is performed when the overcurrent is still flowing.
[0011]
Therefore, the conventional power supply device has a problem that the protection operation cannot be promptly performed when an overload state or a short circuit accident on the load side occurs.
[0012]
In order to promptly perform the protective action against an overload condition or short-circuit accident, the cause of the overcurrent flowing through the load connection terminal may be due to the overload condition or a short-circuit accident occurring on the load side, or It is determined whether another power supply has been connected to the terminal. If the overcurrent is caused by an overload state or a short circuit accident, the overcurrent control is immediately performed to stop the output of the inverter power supply. It is desirable to do so.
[0013]
An object of the present invention is to provide a method of detecting connection of another power supply between load connection terminals for detecting that another power supply is connected between load connection terminals of an inverter power supply device, and an inverter power supply having a function of performing the detection method. It is to provide a device.
[0014]
[Means for Solving the Problems]
The present invention relates to a bridge-type inverter having a current path of a feedback current, and an upper side and a lower side of a bridge circuit each constituted by n (n is an integer of 2 or more) switches turned on in response to a drive signal. A DC power supply circuit for inputting a DC voltage to the inverter circuit; a control device for turning on and off a switch of the inverter circuit so that a waveform of an output voltage of the inverter circuit becomes an AC voltage waveform modulated by PWM; A load connection terminal to which an AC voltage output from the circuit is applied; and a power supply connection between the load connection terminals of the inverter power supply for detecting that another power supply is connected between the load connection terminals of the inverter power supply. It is a detection method.
[0015]
In the present invention, a period in which a drive signal is simultaneously supplied to at least two switches among n switches constituting an upper side of a bridge circuit constituting an inverter circuit, and n switches constituting a lower side of the bridge circuit The control device is configured to control the ON / OFF of the switches of the inverter circuit in a switching pattern in which a period during which the drive signal is simultaneously applied to at least two switches of the at least two switches. When an overcurrent flows through the load connection terminal in a state where at least two switches of the two switches or the switches constituting the lower side of the bridge circuit are on, another power supply is connected between the load connection terminals of the inverter circuit. To be determined.
[0016]
Here, a switch having a feedback current conduction path is a switch having a characteristic that current flows bidirectionally when a drive signal is supplied, or a main switch that is turned on when a drive signal is supplied. A switch having an energizing path for allowing a feedback current to flow in parallel with an electric circuit.For example, a switch configured by connecting a diode for feeding a feedback current in anti-parallel to both ends of a unidirectional switch element such as a MOSFET or a bipolar transistor. And so on.
[0017]
In this specification, the ON state of a switch means a state where a current can flow through a main current path of the switch when a voltage is applied to both ends of the switch.
[0018]
In a bridge-type inverter circuit, when a voltage different from the output voltage of the inverter circuit from any one of frequency, magnitude and phase is applied from another power source between output terminals thereof, a switch at a diagonal position of the bridge circuit. Overcurrent flows not only during a period when the switches are simultaneously turned on, but also during a period when a plurality of switches forming the upper side or a plurality of switches forming the lower side are simultaneously turned on. Overcurrent due to an overload condition or a short circuit fault flows only through switches at diagonal positions of the bridge circuit, and does not flow through a plurality of switches forming the upper side or a plurality of switches forming the lower side of the bridge circuit.
[0019]
Therefore, as described above, a state in which at least two of the switches constituting the upper side of the bridge circuit or at least two of the switches constituting the lower side of the bridge circuit are determined to be in the ON state. When it is determined that another power supply is connected between the load connection terminals of the inverter circuit when an overcurrent is flowing, it is possible to reliably detect that another power supply is connected to the load connection terminal. .
[0020]
When the above detection method is performed, a period during which a drive signal is simultaneously supplied to at least two switches among the n switches constituting the upper side of the bridge circuit, and a period during which the n switches constituting the lower side of the bridge circuit are provided At least one of the periods during which the drive signals are simultaneously supplied to at least two switches is detected as the other power supply connection determination period, and when an overcurrent flows through the load connection terminal in the other power supply connection determination period, the load connection is performed. It is preferable to determine that another power source is connected between the terminals.
[0021]
The detection of the other power supply connection determination period is preferably performed only when it is detected that an overcurrent has flowed through the load connection terminal. With this configuration, it is not necessary to perform the process of detecting the other power supply connection determination period in the steady state, so that the processing performed in the steady state can be reduced, and the responsiveness of the control in the steady state can be improved.
[0022]
In the above configuration, when it is detected that an overcurrent has flown, the normal on / off control of the switches of the inverter circuit is performed as it is, and at least two of the switches constituting the upper side of the bridge circuit are both turned on. State, or whether at least two of the switches constituting the lower side of the bridge circuit are both in the ON state. However, an overcurrent is detected by the current detecting means. When the normal on / off control of the switches of the inverter circuit is interrupted, the n switches constituting the upper side of the bridge circuit of the inverter circuit or the n switches constituting the lower side of the bridge circuit are simultaneously driven for checking. Signal and a load connection terminal when an overcurrent is detected even when the drive signal for checking is applied. To it it may be determined that other power supply is connected.
[0023]
With this configuration, it is possible to immediately determine whether or not another power supply is connected when an overcurrent is detected. Therefore, when an overcurrent is detected, a necessary measure (the output of the inverter circuit and the other power supply) is required. The adjustment of the magnitude, frequency and phase with the output or overcurrent control) can be performed quickly.
[0024]
The inverter power supply device to which the present invention is directed has an energizing path for a feedback current, and the upper and lower sides of the bridge circuit are formed by n (n is an integer of 2 or more) switches that are turned on in response to a drive signal. A bridge type inverter circuit, a DC power supply circuit for inputting a DC voltage to the inverter circuit, and a switch of the inverter circuit for controlling the output voltage waveform of the inverter circuit to be a PWM modulated AC voltage waveform. It comprises a control device and a load connection terminal to which an AC voltage output from the inverter circuit is applied.
[0025]
In the inverter power supply device according to the present invention, the period during which the drive signal is simultaneously supplied to at least two switches among the n switches forming the upper side of the bridge circuit, and the time period of the n switches forming the lower side of the bridge circuit The control device is configured to control the on / off of the switches of the inverter circuit in a switching pattern in which a period during which a drive signal is simultaneously applied to at least two of the switches is generated. In addition to the above configuration, furthermore, a current detector for detecting a current flowing through the load connection terminal and at least two switches or lower sides of the bridge circuit of the upper side of the bridge circuit of the inverter circuit are configured. Detecting that another power supply is connected between the load connection terminals when at least two of the switches are in an ON state and the current detected by the current detector exceeds a set value; Power supply connection detecting means, and when the detecting means detects that a voltage is applied from another power supply, the magnitude, frequency and phase of the output voltage of the inverter circuit are respectively changed to the output voltage of the voltage applied from the other power supply. And voltage waveform adjusting means for controlling so as to match the magnitude, frequency and phase of the signal.
[0026]
The other power connection detection means includes an overcurrent determination means for determining that an overcurrent is flowing when the current detected by the current detector exceeds a set value, and a switch constituting an upper side of a bridge circuit of the inverter circuit. A simultaneous on-period detecting means for detecting, as a simultaneous on-period, a period during which a drive signal is simultaneously applied to at least two of the switches or the switches constituting the lower side of the bridge circuit; When the simultaneous ON period is detected in a state where it is determined that an overcurrent is flowing, another power supply connection determining means for determining that another power supply is connected between the load connection terminals can be provided.
[0027]
BEST MODE FOR CARRYING OUT THE INVENTION
FIG. 1 shows a configuration example of a power supply device 1 to which the present invention is applied. In FIG. 1, reference numeral 2 denotes a three-phase magnet type AC generator, and reference numeral 3 denotes an internal combustion engine that drives a magnet generator 2. The magnet-type alternator 2 includes a magnet rotor (not shown) configured with multiple poles and a stator having three-phase connected power generation coils 2u to 2w. It is attached to the crankshaft of the internal combustion engine 3.
[0028]
Reference numeral 4 denotes a rectifier in which diodes Du to Dw and Dx to Dz are connected in a three-phase bridge. The three-phase AC input terminals 4u to 4w of the rectifier 4 are connected to the three-phase output terminals of the generator 2, respectively. A smoothing capacitor Cd is connected between the DC output terminals 4a and 4b.
[0029]
Reference numeral 5 denotes a bridge-type inverter circuit in which MOSFETs Fu and Fv as switches and Fx and Fy are bridge-connected, and a parasitic diode whose anode faces the source side between the drain and the source of each of the MOSFETs Fu, Fv and Fx and Fy. Dfu and Dfv and Dfx and Dfy are formed. In this example, the upper side of the bridge circuit is configured by MOSFETs Fu and Fv as switches, and the lower side of the bridge circuit is configured by MOSFETs Fx and Fy. The diodes Dfu, Dfv, Dfx, and Dfy form a feedback current conduction path.
[0030]
The pair of input terminals 5a and 5b of the inverter circuit 5 are connected to the output terminals 4a and 4b of the rectifier 4, and the pair of output terminals 5u and 5v of the inverter circuit 5 have a filter circuit 6 comprising inductances L1 and L2 and a capacitor C1, respectively. To the pair of load connection terminals 7u and 7v. A load 9 is connected to the load connection terminals 7u and 7v through a well-known connector 8 composed of an outlet and a plug.
[0031]
11 is a load current detection circuit for detecting a current supplied to the load from the inverter circuit 5, and 12 is a load comprising an operational amplifier OP1 and resistors Ru and Rv connecting the input terminals of the operational amplifier to the load connection terminals 7u and 7v. In the voltage detection circuit, the output of the load current detection circuit 11 and the output of the load voltage detection circuit 12 are input to the control device 13.
[0032]
The control device 13 includes a comparator 13a that compares the output of the load current detection circuit 11 with a reference signal, an A / D converter 13b that converts the output of the load voltage detection circuit 12 into a digital signal, a ROM, a RAM, and a CPU. A microcomputer 13c, a drive signal output circuit 13d for providing drive signals Gu, Gv, Gx and Gy to the gates of the FETs Fu, Fv, Fx and Fy in accordance with a command signal generated by the CPU; An A / D converter 13e for converting the detected value into a digital signal.
[0033]
The voltage between the output terminals of the rectifier 4 is applied to the input terminal of the operational amplifier 14, and the output of the operational amplifier 14 is input to the A / D converter 13e in the control device 13.
[0034]
The control device 13 controls the period in which the drive signals Gu and Gv are simultaneously supplied to the two switches Fu and Fv forming the upper side of the bridge circuit forming the inverter circuit 5 and the two switches Fx forming the lower side of the bridge circuit. , Fy are turned on / off by switches Fu, Fv, Fx, Fy of the inverter circuit in a switching pattern in which a period during which a drive signal is simultaneously applied is generated.
[0035]
The control device 13 also includes a bridge that configures the inverter circuit so as to compensate for a decrease in the output current of the inverter circuit due to a decrease in the output voltage of the rectifier 4 when the output voltage of the rectifier 4 decreases due to an increase in the load current. By increasing the on-duty ratio of one of the switches at the diagonal positions of the circuit, the current supplied from the generator 2 to the inverter circuit 5 through the rectifier 4 is adjusted to be substantially constant.
[0036]
The magnet generator 2 has a characteristic in which the output voltage rapidly decreases with an increase in the output current (a so-called drooping characteristic). When the switches of the inverter circuit are controlled as described above, the output of the generator 2 is controlled. , The output voltage of the rectifier 4 (the voltage input to the inverter circuit 5) can be kept almost constant with respect to the output current.
[0037]
The controller 13 also compares the detected value of the current obtained from the load current detection circuit 11 with the overcurrent determination value by the comparator 13a, and when the detected value of the current exceeds the determination value, switches the inverter circuit (shown in FIG. In the example, the supply of the drive signal to the FETs Fu, Fv, Fx, Fy) is stopped, and the overcurrent control for stopping the output of the inverter circuit is performed.
[0038]
In the inverter power supply device 1 shown in FIG. 1, the three-phase AC voltage output from the generator 2 is converted into a DC voltage by the rectifier 4 and input to the inverter circuit 5. The control device 13 turns on the pair of FETs (Fu, Fy) and (Fv, Fx) at the diagonal positions of the bridge circuit constituting the inverter circuit at the same time for a desired half cycle of the sine wave. While the drive signals (Gu, Gy) and (Gv, Gx) are being applied, the drive signal applied to the lower-stage FET is intermittently switched on and off at a duty ratio proportional to the instantaneous peak value of each sine wave, thereby turning on and off the lower-stage FET. Then, PWM control is applied to the output of the inverter circuit. The voltage output from the inverter circuit 5 is converted into a smooth sine wave voltage through the filter circuit 6, and then applied to the load 9 through the load connection terminals 7u and 7v.
[0039]
The sine wave voltage applied to the load 9 is detected by the load voltage detection circuit 12 and fed back to the control device 13. The CPU 13c of the control device 13 compares each instantaneous magnitude of the output voltage with each instantaneous value (set value) of the desired sine wave voltage, and determines that the instantaneous value of the output voltage is greater than the instantaneous value of the desired sine wave voltage. When the duty ratio is low, the duty ratio of the PWM control is increased, and when the instantaneous value of the output voltage is higher than the instantaneous value of the desired sine wave voltage, the duty ratio of the PWM control is controlled to be small. A desired sinusoidal voltage is generated during 7v.
[0040]
The switches (FETs in the illustrated example) Fu, Fv, Fx and Fy of the inverter circuit 5 shown in FIG. 1 are on / off controlled in a switching pattern as shown in FIG. 2, for example. FIGS. 2A, 2B, 2C, and 2D show drive signals Gu, Gy, Gx, and Gv applied to switches Fu, Fy, Fx, and Fv, respectively. Fx and Fv are turned on when the drive signals Gu, Gy, Gx and Gv are at the H level, respectively. When the drive signals Gu, Gy, Gx, and Gv are at the L level, the switches Fu, Fy, Fx, and Fv are held in the off state, respectively.
[0041]
2 (E) and 2 (F) show the timing when the pair of switches (Fu, Fy) and (Fx, Fv) at the diagonal positions are simultaneously turned on, and FIGS. 2 (G) and 2 (H) show the timing. The timing at which two switches (Fu, Fv) constituting the upper side of the bridge circuit are simultaneously turned on and the timing at which the two switches (Fx, Fy) constituting the lower side are simultaneously turned on are shown.
[0042]
The drive signals Gu, Gy, Gx and Gv shown in FIGS. 2A to 2D are, for example, as shown in FIG. 3, a carrier generator 20 for generating a carrier voltage having a sawtooth waveform, and a sine wave. A sine wave generator 21 for generating a voltage having a waveform, a comparator 22 for comparing a carrier voltage with a sine wave voltage, a comparator 24 for comparing a carrier voltage with a phase inverted by an inverter 23 and a sine wave voltage, The inverters 25 and 26 invert the outputs of the comparators 22 and 24, respectively.
[0043]
In the inverter power supply device shown in FIG. 1, as shown in FIGS. 5 and 6, a load current IL flows through a switch at a diagonal position of the inverter circuit 5. Overcurrent that flows when the load 9 becomes excessive or when a short circuit occurs on the load side also flows through the switch at the diagonal position of the inverter circuit.
[0044]
On the other hand, when another power source P that generates an output voltage having a different magnitude, frequency and / or phase from the output voltage of the inverter circuit 5 is connected between the load connection terminals 7u and 7v, FIG. As shown in FIG. 8, a period during which not only the overcurrent Io flows through the switches at the diagonal positions of the inverter circuit 5 but also the two switches Fu and Fv constituting the upper side of the bridge of the inverter circuit 5 are simultaneously turned on. , An overcurrent Io flows through both switches Fu and Fv, as shown in FIG. Also, during a period in which the switches Fx and Fy constituting the lower side of the bridge of the inverter circuit 5 are simultaneously turned on, an overcurrent Io flows through the switches Fx and Fy as shown in FIG.
[0045]
As described above, as a peculiar phenomenon when another power supply is connected between the load connection terminals, two switches constituting the upper side of the bridge circuit of the inverter circuit and two switches constituting the lower side of the bridge circuit are simultaneously turned on. The overcurrent Io also flows during the period of the state. The present invention utilizes this phenomenon to detect that another power source has been connected between the load connection terminals.
[0046]
That is, when it is detected by the current detecting means 11 that the overcurrent Io has flown through the load connection terminals 7u and 7v, the drive signals are simultaneously supplied to the two switches constituting the upper side of the bridge circuit of the inverter circuit 5. At least one of a period and a period during which a drive signal is simultaneously supplied to the two switches constituting the lower side of the bridge circuit is detected as another power supply connection determination period, and an overcurrent flows through the load connection terminal during the other power supply connection determination period. When flowing, it is determined that another power supply is connected between the load connection terminals.
[0047]
FIG. 11 shows an example of the configuration of a detection device that implements the detection method of the present invention. In FIG. 11, reference numeral 30 denotes a switch pattern that gives an on / off pattern at each instant of the switches constituting the inverter circuit 5. The switch pattern generating means is realized by the CPU 13c. The CPU 13c supplies a drive signal to a predetermined switch to be turned on from the drive signal output circuit according to the switch pattern generated by the switch pattern generation means.
[0048]
31 is an upper side switch simultaneous ON period detecting means for detecting a period in which the switches Fu and Fv constituting the upper side of the bridge are simultaneously turned on from a switch pattern generated by the switch pattern generating means 30; Lower side switch simultaneous ON period detecting means for detecting a period during which the switches Fx and Fy constituting the lower side of the bridge are simultaneously ON from the generated switch pattern. An OR 33 determines whether or not either the condition that the switches forming the upper side of the bridge are on at the same time or the condition that the switches forming the lower side of the bridge are simultaneously on is satisfied. It is a condition determining means. In this example, the upper side switch simultaneous ON period detecting means 31, the lower side switch simultaneous ON period detecting means 32, and the OR condition determining means 33, the lower side of two switches or the bridge circuit constituting the upper side of the bridge circuit of the inverter circuit. The other power supply connection determination period detecting means detects a period in which the drive signals are simultaneously supplied to the two switches constituting the power supply connection determination period.
[0049]
The comparator 13a compares the detected value of the current obtained from the current detector 11 with the overcurrent determination value, and generates an overcurrent detection signal when the current detected by the current detector 11 exceeds the set value. . In this example, the comparator 13a forms overcurrent determination means.
[0050]
The overcurrent detection signal obtained from the comparator 13a is supplied to the AND condition determination unit 34 together with the other power supply connection determination period detection signal generated by the OR condition determination unit 33. The AND condition determining means 34 determines whether or not the overcurrent is flowing by the overcurrent determining means (comparator 13a) while the other power supply connection determination period detection signal is being generated, and the load connection terminals 7u and 7v. The other power supply detection signal indicating that the other power supply P is connected therebetween is generated.
[0051]
In the other power supply connection determination period detected by the other power supply connection determination period detection means by the AND condition determination means, when the overcurrent determination means determines that an overcurrent is flowing, another power supply is applied between the load connection terminals. Other power connection determination means for determining connection is provided.
[0052]
The OR condition determining unit 33 and the AND condition determining unit 34 in FIG. 11 can be realized by causing the CPU 13c to execute a predetermined program.
[0053]
Note that the process of detecting the other power supply connection determination period is preferably performed only when an overcurrent is detected. However, the process of detecting the other power supply connection determination period is always performed, and the upper side of the bridge of the inverter circuit 5 is detected. It is determined whether an overcurrent has been detected each time a period during which the switches constituting the bridge are simultaneously turned on or a period during which the switches constituting the lower side of the bridge are simultaneously turned on is detected. You may do it.
[0054]
In the above example, when it is detected that an overcurrent has flowed, the normal on / off control of the switches of the inverter circuit 5 is performed as it is, and at least two of the switches constituting the upper side of the bridge circuit are connected together. By detecting whether or not at least two switches among the switches constituting the lower side of the bridge circuit are both in the on state, it is possible to detect that the other power supply is connected. However, when overcurrent is detected by the current detecting means 11, the normal on / off control of the switches of the inverter circuit is interrupted, and the two switches Fu, Fv, Alternatively, a drive signal for checking is simultaneously supplied to two switches Fx and Fy constituting the lower side of the bridge circuit, and the switches for checking are provided. It may be determined that other power supply is connected between the load connection terminal when the overcurrent even when the motion signal is applied is detected.
[0055]
In the above example, a MOSFET is used as a switch constituting the inverter circuit 5. However, as shown in FIG. 12, an anti-parallel connection is established between the bipolar transistors TRu, TRv, TRx and TRy and the collector and emitter of these transistors. It is also possible to use feedback feedback path forming diodes Dfu, Dfv, Dfx and Dfy.
[0056]
The switching pattern of the switches of the inverter circuit is not limited to the example shown in FIG. 2, but may be a switching pattern as shown in FIG. FIGS. 4A, 4B, 4C, and 4D show drive signals Gu, Gy, Gx, and Gv applied to switches Fu, Fy, Fx, and Fv, respectively. FIGS. 4E and 4F show timings when the pair of switches (Fu, Fy) and (Fx, Fv) at the diagonal positions are simultaneously turned on, and FIG. 4G shows the upper side of the bridge circuit. At the same time, the two switches (Fu, Fv) constituting the switch are turned on at the same time.
[0057]
In the above example, a single-phase inverter circuit is used. However, the present invention can be applied to a case where an inverter circuit that generates a three-phase or more multi-phase AC voltage is used.
[0058]
【The invention's effect】
As described above, according to the present invention, it is determined that at least two of the switches constituting the upper side of the bridge circuit or at least two of the switches constituting the lower side of the bridge circuit are both in the ON state. When an overcurrent is flowing in this state, it is determined that another power supply is connected between the load connection terminals of the inverter circuit. And an abnormal state such as a short circuit accident on the load side can be reliably detected.
[Brief description of the drawings]
FIG. 1 is a circuit configuration diagram showing a configuration example of an inverter power supply device according to the present invention.
FIG. 2 is a timing chart showing an example of a drive signal given to each switch of the inverter circuit shown in FIG. 1 and a switching pattern of the switch of the inverter circuit.
FIG. 3 is a circuit diagram showing a configuration example of a drive signal generation circuit that can be used to obtain the drive signal shown in FIG.
FIG. 4 is a timing chart showing another example of a drive signal applied to each switch of the inverter circuit shown in FIG. 1 and a switching pattern of the switch of the inverter circuit.
FIG. 5 is an explanatory diagram illustrating a state in which one half wave of a load current flows in the inverter circuit of the inverter power supply device of FIG. 1;
FIG. 6 is an explanatory diagram illustrating a state in which the other half wave of the load current flows in the inverter circuit of the inverter power supply device of FIG. 1;
FIG. 7 is an explanatory diagram illustrating one current path when an overcurrent caused by connection of another power supply flows in the inverter circuit of the inverter power supply device of FIG. 1;
8 is an explanatory diagram illustrating another current path when an overcurrent due to connection of another power supply flows in the inverter circuit of the inverter power supply device of FIG. 1;
FIG. 9 is an explanatory diagram illustrating still another current path when an overcurrent due to the connection of another power supply flows in the inverter circuit of the inverter power supply device of FIG. 1;
FIG. 10 is an explanatory diagram illustrating still another current path when an overcurrent due to the connection of another power supply flows in the inverter circuit of the inverter power supply device of FIG. 1;
FIG. 11 is a block diagram illustrating a configuration example of a detection device that performs the other power supply connection detection method according to the present invention.
FIG. 12 is a circuit diagram showing another configuration example of the inverter circuit.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Inverter generator, 2 ... Generator, 3 ... Internal combustion engine, 4 ... Rectifier, 5 ... Inverter circuit, 6 ... Filter circuit, 7u, 7v ... Load connection terminal, 9 ... Load, 13 ... Control device.

Claims (6)

A bridge-type inverter circuit having a current path for a feedback current, and having an upper side and a lower side of the bridge circuit respectively constituted by n (n is an integer of 2 or more) switches that are turned on in response to a drive signal; A DC power supply circuit for inputting a DC voltage to the inverter circuit, a control device for turning on and off a switch of the inverter circuit so that a waveform of an output voltage of the inverter circuit becomes an AC voltage waveform subjected to PWM modulation, and Detecting that another power supply is connected between the load connection terminals of the inverter power supply device having the load connection terminal to which the output AC voltage is applied, and detecting other power supply connection between the load connection terminals of the inverter power supply device The method,
A period in which a drive signal is simultaneously supplied to at least two switches among the n switches constituting the upper side of the bridge circuit, and a period in which at least two switches among the n switches constituting the lower side of the bridge circuit are simultaneously provided; The control device is configured to perform on / off control of a switch of the inverter circuit with a switching pattern in which a period in which a drive signal is applied is generated,
An overcurrent flows through the load connection terminal in a state where at least two of the switches constituting the upper side of the bridge circuit or at least two of the switches constituting the lower side of the bridge circuit are both on. A method for detecting the connection of another power supply between the load connection terminals of the inverter power supply device when it is determined that another power supply is connected between the load connection terminals of the inverter circuit. A bridge-type inverter circuit having a current path for a feedback current, and having an upper side and a lower side of the bridge circuit respectively constituted by n (n is an integer of 2 or more) switches that are turned on in response to a drive signal; A DC power supply circuit for inputting a DC voltage to the inverter circuit, a control device for turning on and off a switch of the inverter circuit so that a waveform of an output voltage of the inverter circuit becomes an AC voltage waveform subjected to PWM modulation, and Detecting that another power supply is connected between the load connection terminals of the inverter power supply device having the load connection terminal to which the output AC voltage is applied, and detecting other power supply connection between the load connection terminals of the inverter power supply device The method,
A period in which a drive signal is simultaneously supplied to at least two switches among the n switches constituting the upper side of the bridge circuit, and a period in which at least two switches among the n switches constituting the lower side of the bridge circuit are simultaneously provided; The control device is configured to perform on / off control of a switch of the inverter circuit with a switching pattern in which a period in which a drive signal is applied is generated,
A period in which a drive signal is simultaneously supplied to at least two switches among the n switches constituting the upper side of the bridge circuit, and a period in which at least two switches among the n switches constituting the lower side of the bridge circuit are simultaneously provided; Detecting at least one of the driving signal application periods as the other power supply connection determination period,
In the other power supply connection determination period, when an overcurrent is flowing through the load connection terminal, it is determined that another power supply is connected between the load connection terminals. Other power connection detection method. 3. The inverter power supply device according to claim 2, wherein the detection of the other power supply connection determination period is performed only when it is detected that an overcurrent flows through the load connection terminal. Other power connection detection method. A bridge-type inverter circuit having a current path for a feedback current, and having an upper side and a lower side of the bridge circuit respectively constituted by n (n is an integer of 2 or more) switches that are turned on in response to a drive signal; A DC power supply circuit for inputting a DC voltage to the inverter circuit, a control device for turning on and off a switch of the inverter circuit so that a waveform of an output voltage of the inverter circuit becomes an AC voltage waveform subjected to PWM modulation, and Detecting that another power supply is connected between the load connection terminals of the inverter power supply device having the load connection terminal to which the output AC voltage is applied, and detecting other power supply connection between the load connection terminals of the inverter power supply device The method,
When an overcurrent is detected by the current detecting means, the on / off control of the switch of the inverter circuit is interrupted, and the n switches constituting the upper side of the bridge circuit of the inverter circuit, or the lower side of the bridge circuit, A drive signal for checking is simultaneously given to the n switches to be configured,
A load connection terminal of the inverter power supply device, wherein it is determined that another power supply is connected between the load connection terminals when the overcurrent is detected even in a state where the drive signal for checking is given. Other power connection detection method between. A bridge-type inverter circuit having a current path for a feedback current, and having an upper side and a lower side of the bridge circuit respectively constituted by n (n is an integer of 2 or more) switches that are turned on in response to a drive signal; A DC power supply circuit for inputting a DC voltage to the inverter circuit, a control device for turning on and off a switch of the inverter circuit so that a waveform of an output voltage of the inverter circuit becomes an AC voltage waveform subjected to PWM modulation, and And a load connection terminal to which the output AC voltage is applied.
The control device may include a period in which a drive signal is simultaneously supplied to at least two switches among the n switches forming the upper side of the bridge circuit, and at least one of the n switches forming the lower side of the bridge circuit. A switching pattern in which a period during which a drive signal is simultaneously supplied to the two switches is configured to control on / off of the switches of the inverter circuit;
A current detector for detecting a current flowing through the load connection terminal; and at least two switches among switches constituting an upper side of a bridge circuit of the inverter circuit or at least two switches among switches constituting a lower side of the bridge circuit. Other power supply connection detecting means for detecting that another power supply is connected between the load connection terminals when both of the switches are on and the current detected by the current detector exceeds a set value. And the magnitude, frequency and phase of the output voltage of the inverter circuit when the other power supply connection detecting means detects that a voltage is applied from the other power supply, respectively. And a voltage waveform adjusting means for controlling the frequency and the phase so as to match each other. Inverter power supply. The other power supply connection detecting means includes an overcurrent determining means for determining that an overcurrent is flowing when the current detected by the current detector exceeds a set value, and an upper side of a bridge circuit of the inverter circuit. Power supply connection determination period detecting means for detecting a period in which a drive signal is simultaneously applied to at least two switches among switches to be connected or at least two switches among switches constituting the lower side of the bridge circuit as another power supply connection determination period And another power supply is connected between the load connection terminals when it is determined by the overcurrent determination means that an overcurrent is flowing during the other power supply connection determination period detected by the other power supply connection determination period detection means. 6. The inverter power supply device according to claim 5, further comprising a power supply connection determination unit that determines that there is a power supply.

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