JP2013106434A - Power supply identification method for electric power conversion system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve the following problem: Using a power supply with a different voltage magnitude, it is necessary to identify which power supply is connected in charging external storage means, and conventionally a method for adding an auxiliary control wire for power type detection to each of power connectors and reading it on the electric power conversion system side, and a method for consuming charges of a DC intermediate circuit with an AC motor winding when stopping the electric power conversion system have been used; however the former causes a cost increase and the latter requires to control an AC motor so that the motor does not rotate and causes technical difficulty, which goes against further high operation efficiency.SOLUTION: In stopping running of a power phase converter, charges stored in a DC intermediate circuit are discharged to an external storage device via a step-up/down DC-DC converter circuit. Thus, even when a different voltage from a power supply during stopping is applied at the next running start, power supply type is completely identified to prevent generation of wasteful discharging.

Description

  The present invention relates to a power source identification method for a power conversion device having a function of charging an external power storage device with a plurality of power sources having different voltages.

  When charging the power storage device, there are a method of rapidly charging with high voltage and high power, and a method of easily charging with a single-phase AC 100V, for example, power is supplied to a wall outlet even if it takes time. . Thus, when charging an external power storage device with a plurality of power sources having different voltages, it is necessary to instruct the power conversion device which power source is connected by some means. For example, there is a method of adding an auxiliary control line for detecting the power type to each power connector and reading it on the power converter side. However, with this means, it is necessary to provide an extra auxiliary control line, which leads to an increase in the cost of the power converter.

  Even when the auxiliary control line is not provided, it is possible to determine which power source is connected by measuring the DC voltage of the DC intermediate circuit of the power converter, but for example, among the power sources, the three-phase AC200V is If the single-phase AC100V is reconnected immediately after being connected and disconnected, the three-phase AC200V rectified voltage and DC about 280V remain, the single-phase AC100V rectified voltage and DC about 140V. Since it is about twice, it cannot be identified that the single-phase AC 100V is connected as it is.

  In order to solve these problems, before the power converter determines which power source is connected, the DC voltage of the DC intermediate circuit is changed to the magnitude of the DC voltage with the lowest rectified voltage among the connected power sources. It is better if it is lower than this. That is, when the operation of the power converter is stopped, the problem can be solved by discharging the DC voltage of the DC intermediate circuit. As a solution to these problems, there is a method of connecting a discharge resistor at the time of stoppage, but it is not suitable for downsizing and cost reduction of components of the power conversion device. As another means, Patent Document 1 and Patent Document 2 are proposed.

  In the technology according to Patent Document 1 and Patent Document 2, when the power conversion device is stopped, the electric charge stored in the DC intermediate circuit is passed through the winding of the AC motor and consumed by the winding resistance to be converted into heat. However, it is intended to be discharged.

Japanese Patent No. 3289567 Japanese Utility Model Publication No. 63-29391 JP 2000-295715 A (Fig. 6 on page 6 and Fig. 7 on page 7)

“Power Switching Engineering”, The Institute of Electrical Engineers of Japan, The Institute of Electrical Engineers of Japan, August 5, 2003, P90

  However, in such a technique, since the electric charge stored in the DC intermediate circuit of the power conversion device is consumed as heat, the overall efficiency of the power conversion device is reduced, and when operating only with an external power storage device, There are adverse effects such as shortening the operation continuation time per charge. Also, when current is passed through the winding of the AC motor, if the AC motor is not prevented from generating torque, there is a risk that the AC motor will rotate temporarily, and the current control method is technical. Is difficult.

  The present invention has been made in consideration of such problems, and the electric charge stored in the DC intermediate circuit when the power converter is stopped can be easily controlled without adding special hardware. It is an object of the present invention to provide a method for identifying a power source of a power converter having means for discharging an external power storage device.

  According to the first aspect of the present invention, a rectifier configured to connect a plurality of AC power sources and converting AC to DC, a DC intermediate circuit connected to the DC side of the rectifier, and the DC intermediate circuit Is connected between the inverter circuit for driving the AC motor, the external power storage device, and the DC intermediate circuit, and can exchange power bidirectionally between the power storage device and the DC intermediate circuit. In the power conversion device including the bidirectional DC / DC converter configured as described above, when the operation of the power conversion device is stopped, the charge stored in the DC intermediate circuit is converted by the bidirectional DC / DC converter. The charge is transferred to the external power storage device, and the charge of the DC intermediate circuit is discharged, and connected according to the magnitude of the DC voltage of the DC intermediate circuit at the start of the next operation. A power source identifying method of the power conversion apparatus characterized by being to identify the AC power supply of a few.

  The power identification method for a power converter of the present invention includes a rectifier that rectifies an external AC power source, a DC intermediate circuit that includes an electrolytic capacitor, an inverter circuit that drives an external motor, and an external power storage device that is charged and discharged. When the operation of the power converter is stopped, the charge stored in the DC intermediate circuit is transferred to the external power storage device via the step-up / step-down DC / DC converter circuit. It is characterized by discharging.

  The present invention starts the next operation by discharging the electric charge stored in the DC intermediate circuit to an external power storage device when the power conversion device is stopped with simple control without adding special hardware. Sometimes it has the effect of reliably detecting which power source is connected.

  By discharging the electric charge stored in the DC intermediate circuit when the power conversion device is stopped, the portion charged to a high voltage is minimized, which also has an effect of helping to prevent an electric shock during maintenance.

It is a figure which shows the structure of the desirable power converter device in embodiment of this invention. It is a time chart which shows the charge operation at the time of the driving | operation start of the power converter device desirable in embodiment of this invention. It is a time chart which shows the discharge operation | movement at the time of the stop of the power converter device desirable in embodiment of this invention. It is a figure which shows the structure of a buck-boost DC / DC converter circuit among the desirable power converter devices in embodiment of this invention. It is a figure which shows the structure of a rectifier among the desirable power converter devices in embodiment of this invention. It is a figure which shows the structure of an inverter circuit among the desirable power converter devices in embodiment of this invention. It is a time chart which shows the operation | movement at the time of discharge of a buck-boost DC / DC converter circuit among the desirable power converter devices in embodiment of this invention. It is a time chart which shows the conventional discharge operation | movement at the time of the stop of the power converter device which is not desirable in embodiment of this invention. It is an example of the direct current | flow intermediate voltage detection means in embodiment of this invention. It is another example of the direct current | flow intermediate circuit shown to the desirable power converter device in embodiment of this invention.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  A desirable power converter 1 in the embodiment of the present invention shown in FIG. 1 is for driving a rectifier 3 that rectifies external AC power supplies 10 to 12, a DC intermediate circuit 5 that is formed of, for example, an electrolytic capacitor, and an external AC motor 9. Inverter circuit 4 and a step-up / step-down DC / DC converter circuit 2 for charging / discharging an external power storage device 8.

  FIG. 4 is a specific configuration example of the step-up / step-down DC / DC converter circuit 2 shown in FIG. In the figure, 41 to 44 are switching elements, 45 to 48 are free-wheeling diodes, 49 is a DC reactor, and 401 is a capacitor.

  FIG. 5 is a specific configuration example of the rectifier 3 shown in FIG. In the figure, reference numerals 51 to 56 denote rectifier diodes.

  FIG. 6 is a specific configuration example of the inverter circuit 4 shown in FIG. In the figure, reference numerals 61 to 66 denote switching elements, and reference numerals 67 to 69 and 601 to 603 denote reflux diodes.

  The normal operation mode of the desirable power conversion device 1 in the embodiment of the present invention shown in FIG. 1 is as follows.

  When the AC motor 9 shown in FIG. 1 is operated, power is supplied via the external power storage device 8 → the two-pole electromagnetic switch 7 → the bidirectional DC / DC converter circuit 2 → the inverter circuit 4 → the AC motor 9. In another means, external AC power supply 10 (for example, three-phase AC200V) → external power supply connector 13 → tripolar electromagnetic switch 6 → rectifier 3 → DC intermediate circuit 5 → inverter circuit 4 → power via AC motor 9 Supply.

  When the external power storage device 8 shown in FIG. 1 is charged, the external AC power supply 10 (for example, three-phase AC200V) → external power supply connector 13 → three-pole electromagnetic switch 6 → rectifier 3 → DC intermediate circuit 5 → bidirectional power Electric power for charging is supplied via the converter 2 → the two-pole electromagnetic switch 7 → the external power storage device 8. In another means, instead of the external AC power supply 10 (for example, three-phase AC200V) → external power connector 13 in the figure, an external AC power supply 11 (for example, single-phase AC100V) → external power supply connector 14 or an external AC power supply is used. 12 (for example, single-phase AC60V) → external power supply connector 15 can also be used. In the figure, the external power connectors 13 to 15 are configured such that only one of them can be connected by means not shown.

  The specific operations of the specific configuration example of the step-up / step-down DC / DC converter circuit 2 shown in FIG. 4 and the specific configuration example of the inverter circuit shown in FIG. 6 are described in Patent Document 3 and Non-Patent Document 1, respectively. As is well known to those skilled in the art. Further, the operation of the rectifier shown in FIG. 5 is also widely known and will not be described in detail here.

FIG. 2 is a typical example showing a temporal change in the voltage applied to the DC intermediate circuit 5 shown in FIG. 1 when the power is turned on. In the figure, T ₀ is the time when the power is turned on, and T ₁ is the time when it is attempted to detect which power is turned on, usually at the time when the transient phenomenon accompanying the power-on is completed. The broken line in the figure indicates, for example, when the power source is a three-phase AC 200V, and the solid line indicates a single-phase AC 100V. When the power is turned on and the inverter circuit 4 and the bidirectional DC / DC converter shown in FIG. The voltage rises to near the peak value of the power supply voltage. Time magnitude of the sensed voltage at _{T 1,} be one power to determine whether the three-phase AC200V or single phase AC100V, the sensed voltage power supply be about DC280V three-phase AC200V, If it is about DC140V, it will be regarded as single phase AC100V.

FIG. 9 is an example of means for detecting which direct current intermediate voltage is detected and identifying which external power source is connected. In the figure, reference numerals 91 to 96 are voltage dividing resistors, 97 to 99 are comparators, and 901 is a reference power source. The ratio of each voltage dividing resistor and the voltage of the reference power source are determined so that, for example, the DC intermediate voltage shown in FIG. 1 corresponds to 250V, 125V, and 75V, and the output 109 of the comparator 99 shown in FIG. The DC intermediate voltage shown in FIG. 1 changes from “L” to “H” when 75 V or higher, and similarly changes from “L” to “H” when the DC intermediate voltage is 125 V or higher and 108 or 250 V or higher. Table 1 lists these relationships. For example, if 107, 108, and 109 in FIG. 9 are “L”, “H”, and “H”, respectively, the external power supply voltage shown in FIG. Identified.

FIG. 8 is a waveform example in the case where the electric charge stored in the DC intermediate circuit 5 shown in FIG. 1 is not forcibly discharged when the power is turned off, and the electric charge is maintained for a long time after the power is turned off. For example, it has a three-phase AC200V to at power OFF immediately before time T ₃ in FIG. 8 is connected, that when connecting the single phase AC100V at time T ₄ shortly after, the DC as shown by the broken line in FIG. Since the voltage of the intermediate circuit 5 is maintained at about DC 270V, the connected power supply cannot be identified as the single-phase 100V, and is erroneously identified as the three-phase AC 200V.

Figure 3 is a waveform example of forcibly discharging the electric charge stored in the DC intermediate circuit 5 shown in FIG. 1 when the power failure immediately its voltage after power-off time T ₅ is lowered near zero . Therefore, considering the case where it is then powered on again at time T _6, as shown in FIG. 2, since the voltage of the DC intermediate circuit 5 the voltage rises from zero state, at the same figure the time T ₁ Even when the voltage is detected, no false detection is made.

  The main point of the present invention is that, as a means for forcibly discharging the electric charge stored in the DC intermediate circuit 5 shown in FIG. 1 when the power is cut off, the bidirectional DC / DC converter 2 shown in FIG. The electric energy is transferred to the power storage device 8.

  7 shows a desirable control method for forcibly discharging the charge stored in the DC intermediate circuit 5 shown in FIG. 1, the voltage waveform of the DC intermediate circuit 5, and the current flowing through the DC reactor 49 shown in FIG. An example of a waveform and a current waveform flowing in a capacitor constituting the DC intermediate circuit 5 is shown.

  7, (1) to (4) correspond to the gate voltage waveforms of the switching elements 41 to 44 shown in FIG. 4, respectively. In the figure, the corresponding switching element is turned on when each gate waveform is at "H" level, and is turned off when it is at "L" level. That is, in order to forcibly move the charge stored in the DC intermediate circuit 5 shown in FIG. 1 to the power storage device 8 shown in FIG. 1, the switching elements 41 and 44 shown in FIG. Achieve. The simplest on / off method is to set the on period and the off period to constant values.

(5) shown in FIG. 7 is a current waveform flowing through the DC reactor 49 shown in FIG. 4, (6) is a current waveform flowing through a capacitor constituting the DC intermediate circuit 5 shown in FIG. 1, and (7) is a DC waveform shown in FIG. It is a specific example of the voltage waveform of the intermediate circuit 5. FIG. In this example, the ON period and the OFF period of the switching elements 41 and 44 shown in FIG. 4 are 10 μs and 90 μs, respectively. When the switching element 41 and 44 shown in FIG. 4 to conduct at the time T ₁₀ in FIG. 7, the switching element 41 → FIG DC reactor shown in positive → bus 101 → 4 capacitors constituting the DC intermediate circuit 5 shown in FIG. 1 49 → Switching element 44 → DC bus 102 → Current increases in a closed circuit that reaches the negative electrode of the capacitor constituting the DC intermediate circuit 5 shown in FIG. 1, and the electric energy stored in the capacitor moves to the DC reactor 49 during this period To do. When turning off the switching elements 41 and 44 shown in FIG. 4 at time T ₁₁ in FIG. 7, the current flowing in the drawing DC reactor 49 is shown in the positive electrode and 1 of FIG reflux diode 47 → bus 103 → capacitor 401 In a closed circuit from the shunt to the positive electrode of the power storage device 8 → the negative electrode → the bus 104 → the reflux diode 46 → the DC reactor 49, the current gradually decreases because the direction is against the voltage of the capacitor 401 and the like, and the current becomes zero. The electric energy temporarily stored in the DC reactor 49 is transferred to the capacitor 401 and the power storage device 8. Thereafter, similarly, the time T ₁₂ → T ₁₃ → T ₁₄ → T ₁₅ ... Continues until the charge of the DC intermediate circuit becomes almost zero, and the discharge is performed in a short time as shown in FIG. To achieve its purpose.

  In the present embodiment described above, a power source identification method for a power conversion device is provided that has an effect of reliably detecting which power source is connected at the start of operation with simple control without adding special hardware. It can be done.

  The external AC power supplies 11 and 12 shown in FIG. 1 are not limited to an AC power supply, and have the same effect even with an external DC power supply such as an external battery power supply.

  The DC intermediate circuit shown in FIG. 1 is composed of only a capacitor. However, even if it is composed of a DC reactor and a capacitor as shown in FIG. 10, it has the same effect.

  When stopping the operation of the power phase converter, the charge stored in the DC intermediate circuit is discharged to the external power storage device via the step-up / step-down DC / DC converter circuit. Even when a voltage different from the power source is applied, it is possible to reliably identify the power source type and prevent wasteful charge discharge.

DESCRIPTION OF SYMBOLS 1 Power converter device 2 Bidirectional DC / DC converter circuit 3 Rectifier 4 Inverter circuit 5 DC intermediate circuit 6 Three pole electromagnetic switch 7 Two pole electromagnetic switch 8 Power storage device 9 AC motor 10-12 External AC power source 13-15 External power source Connectors 41 to 44 Switching element 45 to 48 Freewheeling diode 49 DC reactor 401 Capacitor 51 to 56 Rectifier diode 61 to 66 Switching element 67 to 69 Freewheeling diode 601 to 603 Freewheeling diode 91 to 96 Voltage dividing resistor 97 to 99 Comparator 901 Reference Power supply 1001 DC reactor

Claims (1)

A rectifier configured to connect a plurality of AC power sources and converting AC to DC;
A DC intermediate circuit connected to the DC side of the rectifier;
An inverter circuit connected to the DC intermediate circuit for driving an AC motor;
Power conversion comprising a bi-directional DC / DC converter connected between an external power storage device and the DC intermediate circuit and configured to exchange power bidirectionally between the power storage device and the DC intermediate circuit In the device, when the operation of the power converter is stopped, the charge stored in the DC intermediate circuit is moved to the external power storage device by the bidirectional DC / DC converter, and the DC Distinguishing the electric charge of the intermediate circuit, and identifying the plurality of connected AC power supplies according to the magnitude of the DC voltage of the DC intermediate circuit at the start of the next operation, Method.

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