JP2006014556A - Dc/dc converter - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To manufacture a step-up/-down DC/DC converter with existing inverter devices. <P>SOLUTION: Using the two inverter devices, respective three-phase output terminals are connected, a reactor is provided between output terminals of two inverters, and a DC power supply is connected to a pn terminal of one inverter and a load is connected to an pn terminal of the other inverter. A pn conduction duty of the load side inverter is fixed and an output voltage is detected with a DC voltage detector. By the detected signal, pn duty of the power supply side inverter is controlled to control an output voltage. Operation stopping of the load side inverter is performed, interlocking with the power supply side inverter. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a step-up / step-down DC / DC converter capable of converting a DC power supply voltage into a DC voltage having an arbitrary voltage and capable of powering and regeneration.

Fig. 1 shows a conventionally known basic configuration of a DC / DC converter that can convert a DC power supply voltage into an arbitrary DC voltage, supply power from the power supply to the load, and regenerate power from the load to the power supply. 3 shows. (For example, see Patent Document 1)
The configuration shown in FIG. 2 is a combination of two reversible current chopper circuits (see Non-Patent Document 1).
In FIG. 3, reference numeral 8 denotes a DC / DC converter, which has power terminals 81 and 82 connected to the positive and negative electrodes of the DC power supply 4 and output terminals 83 and 84 to which the load 5 is connected. The negative output terminal 84 can also be shared with the power supply terminal 82.
86 to 89 are switching elements such as IGBTs of Q1 to Q4, and D1 to D4 freewheeling diodes arranged in reverse parallel. 86-89 comprise the single phase bridge, and the reactor 90 is connected between the alternating current terminals.
A smoothing capacitor is provided between the single-phase bridge and the power supply terminals 81 and 82 and between the single-phase bridge and the output terminals 83 and 84.

According to this configuration, the power supply voltage can be boosted and lowered to be supplied to the load, and the power can be supplied to the load or the power from the load can be regenerated to the power supply.
When the duty for conducting the switching elements Q1 and Q2 is D12, the duty for conducting the switching elements Q3 and Q4 is D34, the power supply voltage is Vi, and the output voltage is Vo, Vo = Vi · (D12 / D34). Therefore, the output voltage can be controlled by appropriately controlling the duty D12 in which the switching elements Q1 and Q2 are conducted and the duty D34 in which the switching elements Q3 and Q4 are conducted.

A configuration of a general inverter device is shown in FIG.
In FIG. 4, 1 is a main circuit part of the inverter device, and 100 is a control part.
The main circuit unit 1 of the inverter device converts the voltage applied to the AC input terminal 11 into DC by the rectifier 12 and charges the DC smoothing capacitor 16 via the reactor 3. Terminals 13 and 14 are provided for connecting the reactor 3. A terminal 15 is also provided on the DC negative line corresponding to the terminal. In parallel with the smoothing capacitor 16, an inverter unit 17 composed of a switching element such as an IGBT and a free-wheeling diode antiparallel to the element is connected. The output of the inverter unit 17 is connected to the output terminal 19 via the current detector 18.
In the control unit 100, the arithmetic circuit 102 generates current commands Iu * to Iw * for each phase based on REF such as a speed setting signal or a torque setting signal from the setting device 101. The adder 104 of the current control circuit 103 obtains an error signal between the current commands Iu * to Iw * of each phase and the current detection signals Iu to Iw of each phase from the current detector 18, and the error signal is an operational amplifier. Through 105, the comparator 108 of the gate generation circuit 107 compares the output with the output of the triangular wave generation circuit 106, and the current duty of each of the switching elements Q1 and Q2, Q3 and Q4, and Q5 and Q6 of the inverter unit 17 is determined. The signal is transmitted to each switching element as a gate signal through the gate amplifier 109. The gate signal is transmitted to each switching element only at the time of operation by the switch 111 operated by a signal from the sequence circuit 110 that controls start and stop.
Note that most of the functions of the control unit 100 are realized by software incorporated in a microcomputer.
JP 2001-268900 A (FIG. 1, FIG. 2, claim 6, claim 7, claim 8, claim 9) Masao Yano and 23 others, “Semiconductor Power Conversion Circuit”, 7th Edition, The Institute of Electrical Engineers of Japan, July 1, 1993, p. 80

  In the present invention, when the step-up / step-down DC-DC converter based on the configuration of FIG. 3 is manufactured, the existing inverter device shown in FIG. 4 is used to achieve it without requiring a new structural design. Is.

  Having two inverter devices and a load DC voltage detector, connecting a DC power source to a DC line terminal of the first inverter device, connecting a DC load to a DC line terminal of the second inverter device, The output terminals of the first and second inverter devices are connected, and the output terminals of the two inverter devices are connected via a reactor. The control circuit of the first inverter device detects the negative DC voltage detection DC voltage control function that controls the duty cycle between the positive power semiconductor element and the negative power semiconductor element so that the load DC voltage matches the DC voltage setting command based on the output of the detector and the DC voltage setting command. Then, the control circuit of the second inverter device performs an operation in which the conduction duty between the power semiconductor element on the positive electrode side and the power semiconductor element on the negative electrode side is constant, and the second inverter device It is intended to operate by operation stop command given from over data device.

Two existing inverter devices having the basic configuration shown in FIG. 4 are used.
The first inverter device of the two units is used as the switching elements 86 and 87 and the smoothing capacitor 85 in FIG.
The three terminals U, V, and W of the output terminal 19 in FIG. 4 are connected, and the three-phase switching elements of the inverter unit 17 are connected in parallel, and are given the same gate signal as described later. It operates as a parallel element.
The second inverter device is also used as the switching elements 88 and 89 and the smoothing capacitor 90 in FIG. As with the first inverter device, the three terminals U, V, and W are connected, and the switching elements for three phases of the inverter unit 17 are connected in parallel, and given the same gate signal as described later. It operates as a completely parallel element.
The switching element on the positive electrode side and the switching element on the negative electrode side of the DC line of the second inverter device operate with a constant current duty.
On the other hand, the duty ratio of the switching element on the positive side and the switching element on the negative side of the DC line of the first inverter device is controlled so that the output voltage matches the set value.

According to the present invention, a step-up / step-down DC / DC converter can be obtained by using two existing inverter devices, adding a DC voltage detector as an external circuit, and changing control software without any structural change. Can be realized.
As a result, the design can be performed in a short period of time and a standard member can be used, so that it can be manufactured at a low cost.
In addition, normally, the four switching elements are ignited and extinguished, and the current duty is changed depending on the magnitude relationship between the power supply voltage and the output voltage and the direction of power (for example, see Patent Document 1). ) Although the four switching elements Q1 to Q4 must be controlled as a unit, in the present invention, the duty of the second inverter device including Q3 and Q4 is fixed to control the switching elements Q1 and Q2. The connection with the first inverter can be eliminated, and the exchange of control signals between the two units can be eliminated. As a result, the only signal required between the two inverter devices is the start / stop signal, the wiring is simplified, and the risk of malfunction due to noise is reduced.

  Two existing inverter devices are used, the output terminals of the two inverter devices are connected to each other, and a reactor is connected between the output terminals of both inverter devices. An output voltage is detected by a DC voltage detector, and DC voltage control is performed by the first inverter device based on the detection signal. The second inverter device operates with a constant duty. The operation of the second inverter device is stopped in conjunction with the first inverter device.

FIG. 1 shows the configuration of an embodiment of the present invention.
In FIG. 1, reference numerals 1 and 2 denote a first inverter device and a second inverter device, which are two existing inverter devices. Reference numerals 100 and 200 denote control units of the respective inverter devices. Reference numerals 14, 15, and 19 denote the same terminals as the positive terminal 14, the negative terminal 15, and the output terminal 19 in FIG. 4, and 24, 25, and 29 denote the second inverter apparatus.
The DC power source 4 is connected to the DC positive terminal 14 and the DC negative terminal 15 of the first inverter device.
The three terminals U, V, and W of the output terminal 19 of the first inverter device are connected together, one end of the reactor 5 is connected to the terminal, and the other end is connected to the output terminal 29 of the second inverter. . Three terminals U, V, and W of the output terminal 29 of the second inverter device are also connected together. A load is connected to the DC positive terminal 14 and the DC negative terminal 15 of the second inverter device.

The arithmetic circuit 112 of the control circuit 100 of the first inverter device outputs the output voltage command 101, the signal of the output voltage detector 7 and, if necessary, the signal from the output current detector 18 of the inverter device. Is made to coincide with the output voltage command 101, the duty ratio of the positive side switching element and the negative side switching element is obtained, and a gate signal is given to the switching element. The gate signal is transmitted to the switching element only during operation by the switch 110 that operates in response to a signal from the sequence circuit 111 that commands operations such as starting and stopping.
The arithmetic circuit 212 of the control circuit 200 of the second inverter device outputs a signal that makes the flow duty of the positive side switching element and the negative side switching element constant. The signal is transmitted to the switching element through the switch 210 only during operation according to the operation stop command received from the sequence circuit 111 of the first inverter device by the sequence circuit 211.

With the above configuration, the second inverter device 2 is operated with a constant duty of the positive-side switching element and the negative-side switching element, and the first inverter device 1 is the voltage commanded by setting the output voltage at 101. Can be controlled.
Further, in this configuration, the main circuit configuration of the two inverter devices is exactly the same as that of the existing inverter device shown in FIG. 4, and the existing inverter device can be used as it is.
As an external circuit, only the output voltage detection circuit 6 is provided, and a signal is sent to the arithmetic circuit 112 of the first inverter device. In addition, the exchange of signals between the first inverter device and the second inverter device is performed only by the start / stop signal given from the sequence circuit 111 of the first inverter device to the switch 210 of the second inverter device 2. is there.

Further details are shown in FIG. 2, the same reference numerals as those in FIGS. 1, 3, and 4 denote the same components. In FIG. 2, the control unit 100 of the first inverter device and the control unit 200 of the second inverter device will be described.
Reference numeral 121 in the arithmetic circuit 112 of the control unit 100 of the first inverter device is a voltage control amplifier circuit. The adder 122 and the operational amplifier 123 are supplied from the output voltage command 101 and the output voltage detector 6 provided outside. An error with respect to the signal is calculated and amplified, and a current command I * is output. 124 calculates the total current It of the detection signals Iu, Iv, Iw of the three current detectors CTu, CTv, CTw constituting the current detector 18. Reference numeral 103 denotes a current control amplifier circuit, which amplifies an error between the current command I * and the current sum It by an adder 104 and an operational amplifier 105 and outputs a duty command D *.
The duty command D * is sent as input signals Du, Dv, and Dw to the gate generation circuit 107 of the existing control unit. Thereafter, the three existing gate generation circuits 107 operate in the same manner, and the switching elements Q1, Q3, Q5 and Q2, Q4, Q6 of the inverter unit each have the same gate signal.
The gate signal is transmitted to the switching element only during operation by the switch 111 that operates according to the start / stop command from the sequence circuit 110 that controls start / stop.

  The arithmetic circuit 212 of the control unit 200 of the second inverter device has a duty setter 202, and the output Dref of the setter is sent as input signals Du, Dv, Dw to the gate generation circuit 207 of the existing control unit. Thereafter, the three existing gate generation circuits 107 operate in the same manner, and the switching elements Q1, Q3, Q5 and Q2, Q4, Q6 of the inverter unit each have the same gate signal. The sequence circuit 210 of the second inverter device receives a start / stop command from the sequence circuit 110 of the first inverter device, and transmits a gate signal to the switching element only during operation by the switch 211. With this operation, the second inverter device operates only during operation of the first inverter device.

  The duty ratio fixed value Dref of the second inverter device must be Dref <Vi / Vo when the power supply voltage is Vi, the output voltage is Vo, and Vi <Vo. And the control range of the maximum voltage and the minimum voltage of the output voltage.

The change of the control unit described above is a part related to the vector control calculation and the current control calculation of the control unit of the existing inverter device, and is made by software, and can be realized by changing the software.
The signal from the DC voltage detector can use the analog input terminal of an existing inverter device. Alternatively, when there is a communication function between the second inverter device and the first inverter device, the DC voltage data detected by the second inverter device is transferred to the first inverter device by the communication function. It can also be realized by sending.
Signals between the sequence circuit 110 of the first inverter device and the 210 of the second inverter device are the normal operation stop display contact of the first inverter device and the emergency stop contact of the second inverter device. Operation interlock terminals such as input terminals can be used. Moreover, when there is a communication function between the second inverter device and the first inverter device, the operation state of the first inverter device is also realized by sending it to the second inverter device by the communication function. it can.
As described above, when there is a communication function between the first inverter device and the second inverter device, it is necessary to provide a DC voltage detector outside or to provide a special wiring for exchanging the operation stop command. Absent.

  The present invention can be used for a DC / DC converter, and can output a DC voltage higher than the DC voltage defined by the power supply AC voltage by using the diode rectifier of the first inverter device. It can also be applied to a DC converter.

It is a block diagram of the DC-DC converter by this invention. (Example 1) 1 is a detailed view of a DC / DC converter according to the present invention. (Example 2) It is a block diagram of a basic step-up / step-down DC-DC converter. Basic inverter configuration diagram

Explanation of symbols

DESCRIPTION OF SYMBOLS 1, 2 The main circuit part of an existing inverter apparatus 3 Reactor 4 DC power supply 5 Reactor 6 Load 7 DC voltage detector 11 Power supply terminal 12 Rectifier circuit 13 Terminals 14, 24 DC line positive terminal 15, 25 DC line negative terminal 16, 26 Smoothing capacitor 17, 27 Inverter unit 18, 28 Current detector 19, 29 Inverter output terminal 100, 200 Inverter control unit 101, 202 Setter 102, 112, 212 Operation unit 103 Current control amplifier 104, 122 Adder 105, 123 Operation Amplifier 106, 206 Triangular wave generator 107, 207 Gate generator 108, 208 Comparator 109, 209 Gate amplifier 110, 210 Sequence circuit 111, 211 Switch 121 Voltage control amplifier 124 Summing device 81, 82 DC power supply terminals 83, 84 DC output Terminal 8 , 91 smoothing capacitor 86 to 89 switching element 90 Reactor

Claims (2)

  The first and second inverter devices have two inverter devices, a DC power source is connected to a DC line terminal of the first inverter device, a DC load is connected to a DC line terminal of the second inverter device, and A DC / DC converter characterized in that all the output terminals are connected and the output terminals of the two inverter devices are connected via a reactor.   The first and second inverter devices have two inverter devices, a DC power source is connected to a DC line terminal of the first inverter device, a DC load is connected to a DC line terminal of the second inverter device, and All the output terminals are connected, the output terminals of the two inverter devices are connected via a reactor, and the first inverter device has a DC voltage control circuit, and a load DC voltage detection signal and A DC voltage setting command is given, and the function of controlling the flow duty between the switching element on the positive electrode side and the switching element on the negative electrode side is controlled by the output of the DC voltage control circuit. The switching element of the negative electrode side and the switching element of the negative electrode side perform an operation with a constant flow duty, and the second inverter device is a stop instruction given from the first inverter device. DC / DC converter, characterized in that the operation by.

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