JP2011259621A - Power circuit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a power circuit capable of attaining low loss and allowing miniaturization.SOLUTION: The power circuit, used for performing mutual conversion between a DC voltage and an AC voltage, comprises: a single-phase-part step-up/down inverter 1 for performing a step-up operation in a part of a plurality of sections segmented in accordance with magnitudes of the DC voltage and the AC voltage and performing a step-up/down operation in the remaining section(s); and a control circuit 2 for controlling the single-phase-part step-up/down inverter 1. The single-phase-part step-up/down inverter 1 includes: four switching elements 10, 12, 14, 16; two AC reactors 20, and 22; and a capacitor 30.

Description

  The present invention relates to a power supply circuit that performs bidirectional conversion between a DC voltage and an AC voltage.

Conventionally, a power supply circuit that performs conversion between a DC voltage and an AC voltage by combining a buck-boost chopper and a single-phase inverter is known (see, for example, Patent Documents 1 and 2). FIG. 14 is a diagram showing a configuration of a conventional power supply circuit. The power supply circuit shown in FIG. 14 includes a step-up / step-down chopper 100 and a single-phase inverter 110. The step-up / down chopper 100 includes a DC reactor 101, switching elements 102 and 103, and smoothing capacitors 104 and 105. The single-phase inverter 110 includes switching elements 111, 112, 113, 114 and a smoothing capacitor 105. In addition, AC reactors 115 and 116 and a smoothing capacitor 117 are connected to the single-phase inverter 110. As shown in FIG. 15, the conversion from the DC voltage E _dc to the AC voltage e _ac is performed by once boosting the DC voltage E _dc to a voltage V _dc higher than the peak value of the AC voltage e _{ac by} the step-up / down chopper 100. The single-phase inverter 110 converts this voltage V _dc into an alternating voltage e _ac .

JP 2008-79439 A JP 2006-158100 A

Incidentally, in the conventional power supply circuit shown in FIG. 14, the DC voltage E _dc is once converted to a higher voltage V _dc , so that there is a problem that the loss accompanying this boosting is large. In addition, two circuits of the step-up / step-down chopper 100 and the single-phase inverter 110 are required, and the step-up / step-down chopper 100 includes the DC reactor 101, so that there is a problem that it is difficult to reduce the size of the apparatus.

  The present invention was created in view of the above points, and an object of the present invention is to provide a power supply circuit that can be reduced in size with low loss.

  In order to solve the above-described problems, a power supply circuit according to the present invention is a power supply circuit that performs mutual conversion between a DC voltage and an AC voltage, and has a magnitude relationship in the comparison of the absolute values of the DC voltage and the AC voltage. Among the sections of the voltage waveform that are categorized correspondingly, perform the operation to boost the DC voltage to AC voltage or the operation to step down the AC voltage to DC voltage in the section where the AC voltage is higher than the DC voltage, and the remaining section Includes a step-up / step-down inverter that performs an operation of stepping down a DC voltage to an AC voltage or an step-up operation of an AC voltage to a DC voltage, and a control circuit that controls the step-up / step-down inverter. The step-up / step-down inverter has two DC terminals for inputting / outputting a DC voltage and two AC terminals for inputting / outputting an AC voltage, and one DC terminal and two AC terminals are connected to each other. A series circuit of a first switching element and a reactor is connected between them, a second switching element is connected between the other DC terminal and each of the two AC terminals, and a capacitor is connected between the two AC terminals. Is connected.

  Since it is not necessary to once boost the voltage to a DC voltage that is higher than the peak value of the AC voltage, loss during conversion can be reduced. Further, since the mutual conversion between the DC voltage and the AC voltage is performed only by the step-up / step-down inverter that does not include the DC reactor, the apparatus can be downsized.

  The control circuit described above turns on the first switching element included in one series circuit and the first switching element included in the other series circuit when the AC voltage is higher than the DC voltage. In the off state, the other two second switching elements are alternately turned on / off to cause the step-up / step-down inverter to perform an operation for increasing the DC voltage to an AC voltage or an operation for decreasing the AC voltage to a DC voltage. ing. Further, when the AC voltage is lower than the DC voltage, the control circuit described above turns on the first switching element included in one series circuit and turns off the second switching element. By alternately turning on and off the first switching element and the second switching element included in the other series circuit, the step-up / step-down inverter is operated to step down the DC voltage to the AC voltage or the AC voltage is converted to the DC voltage. The operation of boosting is performed. As described above, by switching the switching element to be turned on / off (PWM control), the step-up / step-down operation can be performed by one step-up / step-down inverter.

  The control circuit described above includes a PWM signal generation unit that generates a PWM signal whose duty ratio can be changed, and an inverter circuit that inverts the logic of the PWM signal output from the PWM signal generation unit. It is desirable that one of the two switching elements is on / off controlled based on the output signal of the PWM signal generator, and the other is on / off controlled based on the output signal of the inverter circuit. As a result, two switching elements can be alternately turned on and off using one PWM signal, and the configuration can be simplified.

  In addition, when the DC voltage or AC voltage to be converted is given as a voltage command value, the control circuit described above causes the reactor to flow based on the difference between the voltage command value and the actual DC voltage or AC voltage. A current command value generation unit that generates a current command value indicating current, a voltage command value generation unit that generates a voltage command value indicating a voltage across the reactor based on the current command value, and a PWM signal based on the voltage command value It is desirable to provide a PWM signal generation unit that generates Thus, the power flow between the DC voltage and the AC voltage can be arbitrarily controlled by giving the converted voltage as the voltage command value.

It is a figure which shows the whole structure of the power supply circuit of one Embodiment. It is a figure which shows the input-output voltage waveform of a power supply circuit. It is a figure which shows the relationship of the voltage in the case of converting a DC voltage into an AC voltage. It is a figure which shows the relationship between the state of an inverter, and a control circuit in the case of performing the operation | movement which step-downs and converts the positive direct current voltage into alternating current voltage. FIG. 5 is an equivalent circuit diagram of the inverter shown in FIG. 4. It is a figure which shows the relationship between the state of an inverter, and the control circuit in the case of performing the operation | movement which boosts positive polarity DC voltage and converts it into AC voltage. FIG. 7 is an equivalent circuit diagram of the inverter shown in FIG. 6. It is a figure which shows the relationship between the state of an inverter, and a control circuit in the case of performing the operation | movement which step-downs and converts negative DC voltage into AC voltage. FIG. 9 is an equivalent circuit diagram of the inverter shown in FIG. 8. It is a figure which shows the relationship between the state of an inverter, and a control circuit in the case of performing the operation | movement which boosts negative DC voltage and converts it into AC voltage. It is an equivalent circuit schematic of the inverter shown in FIG. It is a figure which shows the detailed structure of the control circuit which converts a DC voltage into a desired AC voltage. It is a figure which shows the detailed structure of the control circuit which converts an alternating voltage into a desired direct voltage. It is a figure which shows the structure of the conventional power supply circuit. It is a figure which shows the input-output voltage waveform of the conventional power supply circuit.

  Hereinafter, an embodiment to which a power supply circuit of the present invention is applied will be described with reference to the drawings.

  FIG. 1 is a diagram illustrating an overall configuration of a power supply circuit according to an embodiment. As shown in FIG. 1, the power supply circuit of the present embodiment includes a single-phase partial buck-boost inverter (hereinafter simply referred to as “inverter”) 1 and a control circuit 2. The inverter 1 includes four switching elements 10, 12, 14, 16, two AC reactors 20, 22, and a capacitor 30. The inverter 1 has two DC terminals a and b and two AC terminals c and d. A series circuit of a switching element 10 and an AC reactor 20 is connected between one DC terminal a and one AC terminal c. A series circuit of a switching element 14 and an AC reactor 22 is connected between one DC terminal a and the other AC terminal d. These switching elements 10 and 14 correspond to a first switching element. A switching element 12 is connected between the other DC terminal b and one AC terminal c. A switching element 16 is connected between the other DC terminal b and the other AC terminal d. These switching elements 12 and 16 correspond to a second switching element. A capacitor 30 is connected between the two AC terminals c and d. The two AC reactors 20 and 22 are magnetically coupled. The control circuit 2 performs on / off control of the four switching elements 10, 12, 14, and 16 included in the inverter 1.

The power supply circuit of the present embodiment has such a configuration, and the schematic operation will be described next. FIG. 2 is a diagram showing input / output voltage waveforms of the power supply circuit 1. In FIG. 2, E _dc and -E _dc indicate the voltage between the DC terminals a and b, and e _ac indicates the voltage between the AC terminals c and d, respectively. In the power supply circuit according to the present embodiment, for example, when the DC voltage E _dc is converted to the AC voltage e _ac , the DC voltage E _dc is directly converted to the voltage V _dc higher than the peak value of the AC voltage e _ac without being once converted. Converted to AC voltage e _ac . Similarly, when the AC voltage e _ac is converted into the DC voltage E _dc , the AC voltage e _ac is directly converted into the DC voltage E _dc without being once converted into the voltage V _dc higher than the peak value. The level of the voltage indicates a magnitude relationship when the absolute values of the DC voltage E _dc and the AC voltage e _ac are compared.

FIG. 3 is a diagram illustrating a voltage relationship when the DC voltage E _dc is converted into the AC voltage e _ac . In FIG. 3, A is a section in which the positive direct current voltage E _dc is stepped down and converted into an alternating voltage e _ac , and B is a section in which the positive direct current voltage E _dc is stepped up and converted into an alternating current voltage e _ac . C represents a section in which the negative DC voltage −E _dc is stepped down and converted into an AC voltage e _ac , and D represents a section in which the negative DC voltage −E _dc is stepped up and converted into an AC voltage e _ac. Yes. Below, the operation | movement corresponding to these each area | region is demonstrated. In FIG. 3, the case for converting a DC voltage E _dc to ac voltage e _ac, and the same when for converting an AC voltage e _ac opposite to the DC voltage E _dc, the same four sections Can be considered separately. However, in this case, the relationship between step-up and step-down is reversed.

(1) Operation of stepping down positive DC voltage E _dc and converting it to AC voltage e _ac (section A)
FIG. 4 is a diagram showing a relationship between the state of the inverter 1 and the control circuit 2 when performing an operation of stepping down the positive DC voltage E _dc and converting it to the AC voltage e _ac . In the inverter 1 shown in FIG. 4, the switching element 10 is turned on during the section A, the switching element 12 is turned off, and the switching elements 14 and 16 are on / off controlled (PWM control) so that the on / off timing of each other is reversed. The

The drive signal for performing the on / off control is generated by the triangular wave generation circuit 50, the voltage comparator 52, and the inverter circuit 54 provided in the control circuit 2. The triangular wave generation circuit 50 generates a triangular wave signal having a lower limit value of 0V and an upper limit value of 1V. In the voltage comparator 52, the triangular wave signal v _TR output from the triangular wave generating circuit 50 is input to the negative input terminal, and the modulation rate command value signal α of 0 to 1V indicating the command value of the modulation rate 0 to 1 is input to the positive input terminal. _BU ^* is input, and a drive signal (PWM signal) that becomes a high / low level according to the magnitude of the voltage of these two signals is output. The switching element 16 is turned on when the drive signal is at a high level, and turned off when the drive signal is at a low level. On the other hand, the switching element 14 is turned on when the drive signal is inverted by the inverter circuit 54, specifically, when the inverted drive signal is at a high level, and turned off when the drive signal is at a low level.

FIG. 5 is an equivalent circuit diagram of inverter 1 shown in FIG. In the equivalent circuit diagram shown in FIG. 5, two AC reactors 20 and 22 are combined into one and represented by an AC reactor 20 ′. As is apparent from the equivalent circuit diagram shown in FIG. 5, the inverter 1 described above operates as a step-down inverter, and the AC is closer to 1 V (the modulation factor is closer to 1) as the modulation rate command value signal α _BU ^* is closer to 1 V. The voltage between the terminals c and d becomes a value close to the DC voltage E _dc . On the other hand, the closer the modulation rate command value signal α _BU ^* is to 0V (the closer the modulation rate is to 0), the closer the voltage between the AC terminals c and d is to a value close to 0V. In this way, the positive voltage step-down operation corresponding to the section A shown in FIG. 3 is performed.

(2) Operation for boosting and converting positive DC voltage E _dc to AC voltage e _ac (section B)
FIG. 6 is a diagram illustrating the relationship between the state of the inverter 1 and the control circuit 2 when performing an operation of boosting the positive DC voltage E _dc and converting it to the AC voltage e _ac . In the inverter 1 shown in FIG. 6, the switching element 10 is turned on during the section B, the switching element 14 is turned off, and the switching elements 12 and 16 are on / off controlled (PWM control) so that the on / off timing of each other is reversed. The

The drive signal for performing the on / off control is generated by the triangular wave generation circuit 50, the voltage comparator 52, and the inverter circuit 54 provided in the control circuit 2. In the voltage comparator 52, the triangular wave signal v _TR output from the triangular wave generating circuit 50 is input to the negative input terminal, and the modulation rate command value signal α of 0 to 1V indicating the command value of the modulation rate 0 to 1 is input to the positive input terminal. _BO ^* is input, and a drive signal (PWM signal) that becomes high / low level according to the magnitude of the voltage of these two signals is output. Specifically, the switching element 12 is turned on when the drive signal is at a high level and turned off when the drive signal is at a low level. On the other hand, the switching element 16 is turned on when the drive signal is inverted by the inverter circuit 54, specifically when the inverted drive signal is at a high level and turned off when the drive signal is at a low level.

FIG. 7 is an equivalent circuit diagram of the inverter 1 shown in FIG. In the equivalent circuit diagram shown in FIG. 7, two AC reactors 20 and 22 are combined into one and represented by an AC reactor 20 ′. As is clear from the equivalent circuit diagram shown in FIG. 7, the inverter 1 described above operates as a booster inverter, and the closer the modulation rate command value signal α _BO ^* is to 0 V (the modulation rate is closer to 0), the AC The voltage between the terminals c and d becomes a value close to the DC voltage E _dc . On the contrary, the closer the modulation rate command value signal α _BU ^* is to 1 V (the closer the modulation rate is to 1), the higher the voltage between the AC terminals c and d is higher than the DC voltage E _dc . In this way, the positive voltage boosting operation corresponding to the section B shown in FIG. 3 is performed.

(3) Operation for stepping down negative DC voltage -E _dc and converting it to AC voltage e _ac (section C)
FIG. 8 is a diagram illustrating a relationship between the state of the inverter 1 and the control circuit 2 when performing an operation of stepping down the negative DC voltage −E _dc and converting it to the AC voltage e _ac . In the inverter 1 shown in FIG. 8, the switching element 14 is turned on during the section C, the switching element 16 is turned off, and the switching elements 10 and 12 are on / off controlled (PWM control) so that the on / off timing of each other is reversed. The

The drive signal for performing the on / off control is generated by the triangular wave generation circuit 50, the voltage comparator 52, and the inverter circuit 54 provided in the control circuit 2. In the voltage comparator 52, the triangular wave signal v _TR output from the triangular wave generating circuit 50 is input to the negative input terminal, and the modulation rate command value signal α of 0 to 1V indicating the command value of the modulation rate 0 to 1 is input to the positive input terminal. _BU ^* is input, and a drive signal (PWM signal) that becomes a high / low level according to the magnitude of the voltage of these two signals is output. Specifically, the switching element 12 is turned on when the drive signal is at a high level and turned off when the drive signal is at a low level. On the other hand, the switching element 10 is turned on when the drive signal is inverted by the inverter circuit 56, specifically when the inverted drive signal is at a high level and turned off when the drive signal is at a low level.

FIG. 9 is an equivalent circuit diagram of inverter 1 shown in FIG. In the equivalent circuit diagram shown in FIG. 9, two AC reactors 20 and 22 are combined into one and represented by an AC reactor 22 ′. As apparent from the equivalent circuit diagram shown in FIG. 9, the inverter 1 described above operates as a step-down inverter, and the AC becomes closer to 1 V (modulation rate is closer to 1) as the modulation rate command value signal α _BU ^* is closer to 1 V. The voltage between the terminals c and d becomes a value close to the voltage −E _dc obtained by inverting the polarity of the DC voltage E _dc . Conversely, the closer the modulation rate command value signal α _BU ^* is to 0V (the closer the modulation rate is to 0), the voltage between the AC terminals c and d is opposite to the DC voltage E _dc and is close to 0V. Value. In this way, the negative voltage step-down operation corresponding to the section C shown in FIG. 3 is performed.

(4) Operation for boosting and converting negative DC voltage -E _dc to AC voltage e _ac (section D)
FIG. 10 is a diagram illustrating a relationship between the state of the inverter 1 and the control circuit 2 when performing an operation of boosting the negative DC voltage −E _dc and converting it to the AC voltage e _ac . In the inverter 1 shown in FIG. 10, the switching element 14 is turned on during the section D, the switching element 10 is turned off, and the switching elements 12 and 16 are on / off controlled (PWM control) so that the on / off timing of each other is reversed. The

The drive signal for performing the on / off control is generated by the triangular wave generation circuit 50, the voltage comparator 52, and the inverter circuit 54 provided in the control circuit 2. In the voltage comparator 52, the triangular wave signal v _TR output from the triangular wave generating circuit 50 is input to the negative input terminal, and the modulation rate command value signal α of 0 to 1V indicating the command value of the modulation rate 0 to 1 is input to the positive input terminal. _BO ^* is input, and a drive signal that becomes high / low level is output according to the magnitude of the voltage of these two signals. The switching element 16 is turned on when the drive signal is at a high level, and turned off when the drive signal is at a low level. On the other hand, the switching element 12 is turned on when the drive signal is inverted by the inverter circuit 55, specifically when the inverted drive signal is at a high level and turned off when the drive signal is at a low level.

FIG. 11 is an equivalent circuit diagram of inverter 1 shown in FIG. In the equivalent circuit diagram shown in FIG. 11, two AC reactors 20 and 22 are combined into one and represented by an AC reactor 22 ′. As is clear from the equivalent circuit diagram shown in FIG. 11, the inverter 1 described above operates as a step-up inverter, and as the modulation factor command value signal α _BO ^* is closer to 1V (the modulation factor is closer to 1), the alternating current is increased. The voltage between the terminals c and d becomes a value close to the voltage E _dc obtained by inverting the polarity of the DC voltage E _dc . Conversely, the closer the modulation rate command value signal α _BO ^* is to 0 V (the closer the modulation rate is to 0), the voltage between the AC terminals c and d is opposite in polarity to the DC voltage E _dc and has an absolute value. The value is higher than the voltage E _dc . In this manner, the negative boost operation corresponding to the section D shown in FIG. 3 is performed.

In this way, by performing the respective on-off control of the switching elements 10 to 16 included in the inverter 1 by the control circuit 2 performs a partial boost operation or step-down operation with respect to the DC voltage E _dc, dc voltage E _It is possible to directly convert _dc to AC voltage e _ac without once boosting _dc to a high voltage. On the contrary, the case where the AC voltage e _ac is converted to the DC voltage E _dc is basically the same, and the control circuit 2 performs on / off control of each of the switching elements 10 to 16 included in the inverter 1. by performing a partial boost operation or step-down operation with respect to the voltage e _ac, it can be converted directly into a DC voltage E _dc without boosting once high voltage AC voltage e _ac.

Next, a detailed control operation performed in the control circuit 2 will be described. FIG. 12 is a diagram showing a detailed configuration of the control circuit 2 that converts the DC voltage E _dc applied to the DC terminals a and b into a desired AC voltage e _ac . In the configuration shown in FIG. 12, current detection units 32 and 33 and voltage detection units 34 and 36 necessary for performing control by the control circuit 2 are added to the inverter 1. The current detection unit 32 detects the reactor current i _LP flowing through the AC reactor 20. The current detection unit 33 detects a reactor current i _LN flowing through the AC reactor 22. The voltage detector 34 detects the voltage E _dc between the DC terminals a and b. The voltage detector 36 detects the voltage _vac between the AC terminals c and d. The voltage detection unit 34 is not used in the operation of converting the DC voltage E _dc into the AC voltage e _ac , but is necessary for the operation (described later) of converting the AC voltage e _ac into the DC voltage E _dc . 12 inverters 1 are included.

  As shown in FIG. 12, the control circuit 2 includes a current command value generation unit 70, adders 80 and 82, a proportional integration controller 86, a modulation factor command signal calculation unit 88, a triangular wave generation circuit 50, a voltage comparator 52, an inverter. The circuit 54 and the SW driver 90 are included. The current command value generation unit 70 includes an adder 72 and a proportional integration adjuster 74. The modulation factor command signal calculation unit 88, the triangular wave generation circuit 50, and the voltage comparator 52 correspond to the PWM signal generation unit, and the proportional integration controller 86 corresponds to the voltage command value generation unit.

As described above, when the inverter 1 shown in FIG. 1 or the like is operated, it is necessary to specify the modulation rate command value signal α _BU ^* at the time of step-down and to specify the modulation rate command value signal α _BO ^* at the time of step-up. . Therefore, first, by obtaining a voltage equation using the equivalent circuit shown in FIG. 5 or FIG. 7, the relationship between the both-ends voltage v _L of the AC reactor 20 ′ and the modulation factor command value signal is derived.

  Using the equivalent circuit diagram during step-down shown in FIG. 5, the voltage equation is obtained as follows.

α _BU ^* E _dc = v _L + | e _ac | (1)
Here, v _L is the voltage across the AC reactor 20 ′. Note that the equivalent circuit shown in FIG. 9 also has basically the same configuration, and the voltage equation is the same as the equation (1). When the equation (1) is modified, it becomes as follows.

v _L = α _BU ^* E _dc − | e _ac | (2)
Further, when the voltage equation is obtained using the equivalent circuit at the time of boosting shown in FIG. 7, it is as follows.

E _dc + v _L = (1−α _BO ^* ) | e _ac | (3)
Note that the equivalent circuit shown in FIG. 11 also has basically the same configuration, and the voltage equation is the same as the equation (3). When the expression (3) is modified, it becomes as follows.

v _L = (1−α _BO ^* ) | e _ac | −E _dc (4)
Meanwhile, 'Lac inductance, AC reactor 20' AC reactor 20 and the current flowing in the i _L, between the v _L and i _L, the following relationship.

v _L = Lac (di _L / dt) (5)
As described above, it can be seen that v _L can be continuously controlled using the modulation factor command value signal α _BU ^* or α _BO ^* , and i _L can be linearly controlled. In the control circuit 2 shown in FIG. 12, the configuration subsequent to the adder 80 is to obtain v _L and further to obtain α _BU ^* or α _BO ^* by giving i _L.

That is, the adder 80 detects the current i _L (detected by the current detection unit 32) actually detected by the current detection units 32 and 33 from the current command value i _L ^* (described later) input to one input terminal. a current i _LP, the input current value obtained by subtracting the current i _L is obtained) by synthesizing the adder 82 and the current i _LN detected by the current detecting section 33 (difference value) to the proportional integral controller 86 To do. The proportional-plus-integral controller 86 obtains and outputs a voltage command value v _L ^* , which is a command value of the voltage across the AC reactor 20 ′ necessary for flowing the input current value, by proportional-integral control. The modulation factor command signal calculation unit 88 calculates and outputs the modulation factor command value signal α _BU ^* or α _BO ^* using equation (2) at the time of step-down and equation (4) at the time of step-up. These modulation factor command value signals are input to the positive input terminal of the voltage comparator 52. The SW driver 90 is directly inputted with the output signal (PWM signal) of the voltage comparator 52 and is inputted with a signal obtained by inverting the logic of the output signal, and includes four kinds of signals including these two kinds of PWM signals. The drive signals S1, S2, S3, and S4 are input to the switching elements 10, 12, 14, and 16 of the inverter 1, respectively. The contents of these four types of drive signals S1, S2, S3, S4 are switched corresponding to each of the four types of sections A to D shown in FIG.

For the section A (positive polarity, at the time of step-down), the following drive signals are used to control each switching element shown in FIG.
Driving signal S1 input to the switching element 10: High level signal Driving signal S2 input to the switching element 12 Low level signal Driving signal S3 input to the switching element 14 Output signal of the inverter circuit 54 Drive signal S4 input to the switching element 16: output signal of the voltage comparator 52.

For section B (positive polarity, during boosting), the following drive signals are used to control each switching element shown in FIG.
Drive signal S1 input to switching element 10: High level signal Drive signal S2 input to switching element 12: Output signal of voltage comparator 52 Drive signal S3 input to switching element 14: Low level Drive signal S4 input to signal / switching element 16: output signal of inverter circuit 54.

For the section C (negative polarity, step-down), the following drive signals are used to control each switching element shown in FIG.
Drive signal S1 input to switching element 10: Output signal of inverter circuit 54 Drive signal S2 input to switching element 12: Output signal of voltage comparator 52 Drive signal S3 input to switching element 14: High Level signal / Drive signal S4 input to the switching element 16: Low level signal.

For the section D (negative polarity, during boosting), the following drive signals are used to control the switching elements shown in FIG.
Driving signal S1 input to switching element 10: Low level signal Driving signal S2 input to switching element 12: Output signal of inverter circuit 54 Driving signal S3 input to switching element 14: High level signal Drive signal S4 input to the switching element 16: output signal of the voltage comparator 52.

Next, generation of the current command value i _L ^* will be described. As described above, the inverter 1 can be controlled by inputting the current command value i _L ^* to one input terminal of the adder 80, but the DC voltage E _dc applied to the DC terminals a and b can be changed. The current command value i _L ^* necessary for conversion to the desired AC voltage e _ac is generated by the current command value generation unit 70. In the current command value generation unit 70, a voltage command value v _ac ^* (= E _m sin (ωt)) corresponding to a desired AC voltage e _ac is input to one input terminal of the adder 72, and the other input terminal. The actual voltage _vac between the AC terminals c and d is input, and a voltage designation value corresponding to the difference between these is input to the proportional-plus-integral controller 74. The proportional-integral controller 74 obtains and outputs a current command value i _L ^* corresponding to the input voltage command value by proportional-integral control. The generated current command value i _L ^* is input to the adder 80. In this way, by inputting the converted output voltage as the command value v _ac ^* , it is possible to reliably convert the DC voltage E _dc shown in FIG. 2 to the AC voltage e _ac .

FIG. 13 is a diagram illustrating a detailed configuration of the control circuit 2 that converts the AC voltage e _ac applied to the AC terminals c and d into a desired DC voltage E _dc . The control circuit 2 shown in FIG. 13 has a configuration in which the current command value generation unit 70 is replaced with a current command value generation unit 60 with respect to the control circuit 2 shown in FIG. The current command value generation unit 60 includes an adder 62, a proportional integration adjuster 64, and a multiplier 66. The current command value i _L ^* necessary for converting the AC voltage e _ac applied to the AC terminals c and d into the desired DC voltage E _dc is generated by the current command value generation unit 60.

In the current command value generation unit 60, the voltage command value E _dc ^* corresponding to the desired DC voltage E _dc is input to one input terminal of the adder 62, and the direct current detected by the voltage detection unit 34 is input to the other input terminal. The actual voltage E _dc between the terminals a and b is input, and a voltage designation value corresponding to the difference between these is input to the proportional-plus-integral regulator 64. The proportional-plus-integral controller 64 obtains and outputs the amplitude value | i _L ^* | of the current command value i _L ^* corresponding to the input voltage command value by proportional-integral control. The multiplier 66 is synchronized with the amplitude value | i _L ^* | output from the proportional-plus-integral regulator 64 and the actual voltage v _ac (the AC voltage e _ac between the AC terminals c and d detected by the voltage detector 36. Current command value i _L ^* is generated by multiplying the signal by a sine wave signal having the same frequency and phase. The generated current command value i _L ^* is input to the adder 80. In this way, by inputting the converted output voltage as the command value E _dc ^* , the conversion from the AC voltage e _ac shown in FIG. 2 to the DC voltage E _dc can be reliably performed.

  As described above, in the power supply circuit according to the present embodiment, it is not necessary to once increase the voltage to a DC voltage (absolute value) higher than the peak value of the AC voltage (absolute value), and therefore loss during conversion can be reduced. Further, since the mutual conversion between the DC voltage and the AC voltage is performed only by the inverter 1 that does not include the DC reactor, the apparatus can be reduced in size. Further, the step-up / step-down inverter 1 can perform the step-up operation and the step-down operation by switching the switching elements 10 to 16 that perform on / off control (PWM control). Furthermore, it is possible to arbitrarily control the power flow between the DC voltage and the AC voltage by giving the converted voltage as a voltage command value.

In the embodiment described above, the conversion to the AC voltage e _ac from the DC voltage E _dc using the configuration shown in FIG. 12, DC from the AC voltage e _ac using the configuration shown in FIG. 13 voltage E _dc However, in order to perform the bidirectional conversion operation by the inverter 1, the control circuit 2 includes both the configuration shown in FIG. 12 and the configuration shown in FIG.

  According to the present invention, since it is not necessary to step up to a DC voltage that is higher than the peak value of the AC voltage, loss during conversion can be reduced. Further, since the mutual conversion between the DC voltage and the AC voltage is performed only by the inverter 1 that does not include the DC reactor, the apparatus can be reduced in size.

DESCRIPTION OF SYMBOLS 1 Single phase partial buck-boost inverter 2 Control circuit 10, 12, 14, 16 Switching element 20, 22 AC reactor 30 Capacitor 32, 33 Current detection part 34, 36 Voltage detection part 50 Triangular wave generation circuit 52 Voltage comparator 54 Inverter circuit 60 , 70 Current command value generation unit 62 Adder 64, 74, 86 Proportional integral controller 66 Multiplier 68 Sine wave signal generation unit 72, 80, 82 Adder 88 Modulation rate command signal calculation unit 90 SW driver

Claims (5)

A power supply circuit that performs mutual conversion between DC voltage and AC voltage,
Among the plurality of sections of the voltage waveform divided in accordance with the magnitude relationship in the absolute value comparison of the direct current voltage and the alternating current voltage, the direct current voltage is converted into the alternating current voltage in a section where the alternating current voltage is higher than the direct current voltage. A step-up / step-down operation that performs an operation of stepping up the AC voltage or stepping down the AC voltage to the DC voltage, and performing an operation of stepping down the DC voltage to the AC voltage or an operation of boosting the AC voltage to the DC voltage in the remaining section. An inverter;
A control circuit for controlling the step-up / down inverter,
The step-up / down inverter has two DC terminals for inputting / outputting the DC voltage and two AC terminals for inputting / outputting the AC voltage,
A series circuit of a first switching element and a reactor is connected between the one DC terminal and each of the two AC terminals,
A second switching element is connected between the other DC terminal and each of the two AC terminals,
A power supply circuit, wherein a capacitor is connected between the two AC terminals. In claim 1,
The control circuit turns on the first switching element included in one of the series circuits when the AC voltage is higher than the DC voltage, and the first circuit included in the other series circuit. In the state where the switching element is turned off, the other two second switching elements are alternately turned on / off, whereby the step-up / step-down inverter is operated to boost the DC voltage to the AC voltage or the AC voltage is A power supply circuit characterized by causing an operation to step down to a DC voltage. In claim 1 or 2,
When the AC voltage is lower than the DC voltage, the control circuit turns on the first switching element included in one of the series circuits and turns off the second switching element. Thus, by alternately turning on and off the first switching element and the other second switching element included in the other series circuit, the DC voltage is stepped down to the AC voltage by the buck-boost inverter. A power supply circuit that performs an operation to increase the AC voltage to the DC voltage. In claim 2 or 3,
The control circuit includes a PWM signal generation unit that generates a PWM signal whose duty ratio can be changed, and an inverter circuit that inverts the logic of the PWM signal output from the PWM signal generation unit, and performs on / off control alternately 2 One of the two switching elements is on / off controlled based on the output signal of the PWM signal generator, and the other is on / off controlled based on the output signal of the inverter circuit. In claim 4,
The control circuit includes:
When the DC voltage or the AC voltage to be converted is given as a voltage command value, the current flowing through the reactor is indicated based on the difference between the voltage command value and the actual DC voltage or the AC voltage. A current command value generator for generating a current command value;
Based on the current command value, a voltage command value generation unit that generates a voltage command value indicating a voltage across the reactor, and
The PWM signal generator for generating the PWM signal based on the voltage command value;
A power supply circuit comprising:

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