JP2544522B2 - Power regeneration device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power regeneration device connected to a DC circuit portion of an inverter device for regenerative braking of an AC motor which is a load of the inverter device.

[0002]

2. Description of the Related Art FIG. 4 is a block diagram showing a conventional power regeneration device connected to an inverter device. In the figure, 1 is an AC power supply of commercial frequency, 2 is a general-purpose inverter device that outputs an alternating voltage of arbitrary voltage and frequency, an induction motor is a load of the inverter device 2, and 4 is a braking of the induction motor 3 during braking. It is a power regeneration device that regenerates energy to the AC power supply 1, and is usually housed in a case independent of the general-purpose inverter device 2 and connected to the DC circuit section of the inverter device 2 by wiring.

In the inverter device 2, 5 is a diode bridge as a converter for converting AC of commercial frequency supplied from the AC power supply 1 into DC, 6 is a resistor for limiting current, 7 is an electrolytic capacitor for smoothing, 8 is a contactor contact, which is in an open state at the time of initial charging of the capacitor 7, charges the capacitor 7 through the resistor 6, closes after charging is completed, and shorts the resistor 6, 9 is an inverter bridge, and The input is inversely converted into an alternating current and the alternating current of a predetermined voltage and frequency is supplied to the induction motor 3.

In the power regeneration device 4, 10 is a resistor for limiting current, 11 is an AC reactor, 12 is a transistor bridge, and a transistor 12 as a switching element is used.
It is configured by combining 6 sets of arms in which a and the free wheeling diode 12b are connected in parallel. 13 is a phase detection circuit for detecting the phase of the AC power supply 1, 14 is a regenerative state determining means for determining whether or not the inverter 2 is in a regenerative state, and 15 is a transistor bridge 12 based on the output of the regenerative state determining means 14. It is a control means for controlling. When the transistor bridge 12 operates as a converter, the control means 15 turns on and off the transistor 12a in synchronization with the AC power supply 1,
The regenerative operation is performed in a phase such that the power factor becomes approximately 1.

Next, the operation will be described. The alternating current supplied from the alternating current power source 1 is converted into direct current by the diode bridge 5, the capacitor 7 is charged first through the limiting resistor 6, and after the charging is completed, the contact 8 is closed and electricity is supplied without going through the limiting resistor 6. The capacitor 7 is smoothed by the capacitor 7, is inversely converted into an alternating current of a predetermined voltage and frequency by the inverter bridge 9, and is supplied to the induction motor 3 which is a load. It should be noted that the AC power supply 1 is supplied to the transistor bridge 12 via the power regeneration device 4, that is, via the resistor 10 and the AC reactor 11.
It is converted into direct current by the freewheeling diode 12b in the transistor bridge 12 and charges the capacitor 7 of the inverter device 2. That is, when the induction motor 3 is normally operated by the inverter device 2, the transistor bridge 12 of the power regeneration device 4 operates together with the diode bridge 5 as a forward converter.

On the other hand, when the energy from the AC motor 3 is regenerated for braking, the inverter bridge 9 operates as a forward converter, and the regenerative power charges the capacitor 7. The regeneration discriminating means 14 detects that the terminal voltage of the capacitor 7 has risen, and operates the transistor bridge 12 as an inverse converter to regenerate electric power in the AC power supply 1. In this case, the AC reactor 11 is used to limit the current change rate when the phase of the transistor bridge 12 is controlled. That is, it is effective in preventing overcurrent due to a sudden change of the AC power supply 1. The resistor 10 is also used to limit the peak value of the current.

In the above-mentioned conventional example, the energy is regenerated to the power source 1 when the induction motor 3 is braked. As another braking method of the induction motor 3, for example, Japanese Patent Laid-Open No. 63-63
-48176, Japanese Utility Model Laid-Open No. 1-143296, etc., a DC power consumption type braking method, that is, a voltage rise between PN terminals of a DC circuit in an inverter device is detected, and if this voltage rises above a predetermined voltage , There is a method in which a braking force is obtained by passing a current through a resistor connected between the PN terminals and consuming the braking energy as Joule heat.

[0008]

A conventional electric power regeneration device 4
Since it is configured as described above, when it is externally attached as an option of a general-purpose inverter, and if the wiring is incorrect at the terminal PN of the DC circuit unit of the inverter device 2, that is, if the positive and negative electrodes are reversely connected, Transistor bridge
There is a problem in that there is a risk that the positive and negative electrodes are short-circuited by the twelve freewheeling diodes 12b and are easily destroyed. That is, the circuit configuration as described above does not have a protection function against PN reverse connection, and it was a major problem to solve this problem when making it an option.

The present invention has been made to solve the above problems, and an inverter with a power regenerative braking device that will not be destroyed even if an external power regenerative device is erroneously wired to an inverter device. The purpose is to obtain the device.

[0010]

According to a first aspect of the present invention, there is provided a power regeneration device which converts an input from an AC power source into a direct current and outputs the direct current, and reverses a direct current input from the direct current output side to an alternating current. A conversion circuit having a bridge structure of an arm in which a switching element and a diode are connected in parallel so as to be converted and can be regenerated to the AC power supply, and a switching means inserted in the DC output side of the conversion circuit and initially in an open state. And a signal for detecting the DC voltage of each of the conversion circuit side and the DC output side of the opening / closing means, and closing the opening / closing means in the open state when the voltage values are equal to or more than a predetermined value and the polarities match. And an opening / closing signal output means for outputting.

A power regeneration device according to a second aspect of the present invention is the power regeneration device according to claim 1, wherein the power regeneration device is inserted between the positive and negative electrodes between the DC side of the conversion circuit and the switching means to smooth DC. Connected to a DC input side of the inverter unit in an inverter device that includes a converter unit that converts an AC input from an AC power supply into a DC and an inverter unit that reversely converts the DC into an AC and outputs the AC motor. It is configured as possible.

[0012]

According to the first aspect of the present invention, the conversion circuit converts the alternating current input from the alternating current power source into direct current and outputs the direct current, and at the time of power regeneration, controls the switching element in which the direct current input from the direct current output side is bridged. By doing so, the switching signal output means detects the DC voltage on the capacitor side and the DC output side of the switching means which is initially in an open state before being converted back to the AC power source and regenerated by the AC power source. When the value is greater than or equal to a predetermined value and the polarities match, a signal for opening and closing the opening / closing means is output.

The DC input / output terminal in the second aspect of the invention is connected to the DC input side of the inverter section of the inverter device, supplies the DC smoothed by the capacitor when the AC motor is running, and supplies the braking energy when braking. Is regenerated to the AC power supply using the capacitor as a buffer.

[0014]

EXAMPLES Example 1. One embodiment of the first and second inventions will be described with reference to FIGS. FIG. 1 is a circuit diagram of an inverter device and a power regeneration device. The power regeneration device has a circuit portion housed in an external type case and connected to the inverter device. FIG. 2 is a circuit diagram of a contactor closing determination circuit as an open / close signal output means in the power regeneration device shown in FIG. 1, and FIG. 3 is an explanatory diagram of operation and erroneous connection of the power regeneration device and the inverter device. In the figure, those denoted by the same reference numerals as those of the conventional example indicate the same or equivalent parts as those of the conventional example.

In FIG. 1, 4A is a power regeneration device,
In this power regeneration device 4A, 16 is a limiting resistor for suppressing the charging current of an electrolytic capacitor 17 described later, 17 is a smoothing electrolytic capacitor disposed on the direct current side of the regenerative control device, and 18a is its limiter. Contactor contacts 18b and 18c connected in parallel with the resistor 16 are contactor contacts inserted between the positive electrode P and the negative electrode N of the electrolytic capacitor 17 and the DC side input, and the contactor contacts 18a to 18c are simultaneously opened and closed. The same contactor is used. Further, 19 is a contactor closing judgment circuit as an opening / closing signal output means for judging the closing timing of the contactor contacts 18a to 18c, and 38 is a contactor closing signal.

The next operation will be described. Since the regenerative control system is exactly the same as the conventional example shown in FIG. 4, the description will be given here focusing on the connection sequence of the circuit of the inverter device 2 and the regenerative control device 4 when the power is turned on. When the AC power supply 1 is turned on, it is converted into direct current through the diode bridge 5 of the inverter device 2, the capacitor 7 is charged through the limiting resistor 6 for initial charging, and the contact 8 is closed after completion of charging in the same manner as in the conventional case. is there. On the other hand, in order to charge the capacitor 17 also on the regenerative controller side, the freewheeling diode 11b of the transistor bridge 12 operates as a forward exchanger,
The capacitor 17 is charged via the limiting resistor 16. However, at this time, the contactor contacts 18a, 18b, 18c are in the open state, and the DC circuit section of the inverter device 2 and the regenerative control device 4 are in a disconnected state.

Next, the conditions for charging the contactors 18a, 18b, 18c will be described. In FIG. 2, 7 is an electrolytic capacitor on the side of the inverter device 2, 17 is an electrolytic capacitor for a regenerative control device, 30a to 30c and 32a to 32c are voltage dividing resistors, 31 and 33 are isolation amplifiers, 34 is a comparator, and 35 Is a zero clamp circuit for a negative input, and 36 is an arithmetic element (CPU). 37 is an LED as a reverse connection alarm lamp, and 39 is a protective resistor for the LED 37. Further, 38 is a contactor signal for opening and closing the contactor contacts 18a-18c.

Since the capacitors 7 and 17 are basically charged by the same AC power supply 1, their DC voltages should be the same, and the contactor closing signal 38 should be output when both voltages match. To ensure safety, the contactor is turned on only when the following three conditions for detecting positive / negative reverse connection are satisfied.

That is, (1) The output of the isolation amplifier 31 is not less than the peak value of the minimum value of the specified input voltage. (Eg AC
If it is 180V, AC180 × √2 = 255V or more) ■ The output of the isolation amplifier 33 must be the peak value of the minimum value of the specified input voltage. (2) The output of the isolation amplifier 33 does not output a negative voltage (determined by the comparator 34).

When the above three conditions are satisfied, the computing element 36 outputs a contactor closing signal 38 after a certain fixed time (more than the inverter charging time constant) has elapsed. By the way, isolated amplifier
The reference numeral 33 outputs positive and negative outputs to the positive and negative inputs. Therefore, the ration of the comparator 34 is a negative value, and at the time of the negative input, the zero voltage is input so that the negative input does not enter the arithmetic element 36.
It requires a clamp circuit 35 to clamp to.

By providing the contactor closing determination circuit 19 as described above, the no-fuse breakers 22 and 23 are provided between the AC power supply 1, the inverter device 2 and the power regeneration device 4, respectively, as shown in FIG. Breaker 2 etc.
Even if the charging of 3 and 23 is not performed at the same time and the charging and discharging of the capacitors 7 and 17 are performed one after the other, contactor contact 18a is provided until the capacitors 7 and 17 are completely charged.
~ 18c does not close. That is, if one of the breakers 22 and 23 is not turned on, the contactor contacts 18a to 18c maintain the open state.

Further, as shown in FIG. 3, the inverter device 2
PN of the DC circuit part of DC and DC input / output terminal P of the power regeneration device 4
_{Even when the} polarities of the wirings 20a and 20b between ₂ and N ₂ are wrongly reversed and connected, the comparator 34 in the contactor closing determination circuit 19 operates and the arithmetic element 36 which monitors the input detects the reverse connection, The alarm lamp (LED) 37 is turned on to warn of the abnormality, and the contactor closing signal 38 is not output to keep the contactor contacts 18a to 18c open.

In the contactor turn-on determination circuit 19 shown in FIG. 2, both 31 and 33 are realized by an insulation amplifier, but the insulation amplifier 31 may be a photocoupler. On the other hand, if the isolation amplifier 33 is replaced by a photocoupler, the circuit configuration is such that the N-side potential is regulated by the negative electrode potential on the inverter side until the contactor is turned on. Also, the negative input is judged by the comparator 34 as the closing condition,
If this condition does not exist and it is attempted to judge the reverse connection only by matching 31 and 33, the reverse connection is made even if the AC power supply sequence of the inverter and the regenerative control device is not the same as shown in FIG. 3, that is, when there is a time delay. There is a possibility of misjudgment, which is not preferable.

As described above, the power regeneration control device has the electrolytic capacitor 17 on the DC side thereof, and the electrolytic capacitor 17
17 is inserted between a transistor bridge 12 which is a DC / AC converter and a rush current suppressing circuit composed of a parallel circuit of a contactor contact 18a and a resistor 16, while an electrolytic capacitor 17
Contact terminals 18 on both the positive and negative terminals between DC terminals P ₂ and N _{2 of}
By having b and 18c, it is possible to protect and detect the reverse connection on the DC side.

Further, since the electrolytic capacitor 17 is added in parallel with the capacitor 7 of the inverter device 2,
It can be expected that the ripple voltage due to the DC wiring will be reduced, the ripple current will be reduced during the power running operation of the inverter, and the withstand voltage will be improved.

[0026]

As described above, according to the first aspect of the present invention, the alternating current input from the alternating current power source is converted into the direct current and output, and the direct current input from the direct current power source side at the time of power regeneration is converted into the alternating current. On the DC side of the conversion circuit that reverse-converts and outputs to the AC power supply,
A signal for closing the opening / closing means which is provided with an opening / closing means which is initially in an open state, detects a DC voltage on both sides of the opening / closing means, and has a voltage value of a predetermined value or more, and which is in an open state due to polarity matching. Since the switching signal output means for outputting is provided, when connecting the DC side to a DC power source,
There is an effect that it is possible to obtain the one that can protect the conversion circuit from the incorrect connection with respect to the polarity.

Further, according to the second invention, in the power regeneration device of the first invention, the smoothing capacitor is provided, and the power regeneration device can be connected to the DC input side of the inverter unit in the inverter device. The power regeneration function can be easily added, and the existence of the smoothing capacitor can reduce the ripple current of the inverter device.

[Brief description of drawings]

FIG. 1 is a circuit diagram of a power regeneration device and an inverter device according to an embodiment of the first and second inventions.

FIG. 2 is a circuit diagram of a contactor closing determination circuit as a DC voltage detection / comparison means in the power regeneration device shown in FIG.

FIG. 3 is an explanatory diagram of operation and erroneous connection of the power regeneration device and the inverter device.

FIG. 4 is a circuit diagram of a conventional power regeneration device and an inverter device.

[Explanation of symbols]

 1 AC power supply 2 Inverter device 3 Induction motor 4 Power regeneration device 6, 10, 16 Resistor 7, 17 Electrolytic capacitor 9, 12 Transistor bridge 13 Phase detection circuit 14 Regeneration discrimination circuit 15 Transistor bridge control circuit 19 Contactor input judgment circuit

Claims (2)

(57) [Claims] 1. A switching element and a diode capable of converting an input from an AC power supply into a direct current and outputting the converted direct current, and reversely converting a direct current input from the direct current output side into an alternating current to regenerate the alternating current power supply. Converter circuit in which arms connected in parallel are connected to each other in a bridge structure, opening / closing means initially inserted into the DC output side of the converting circuit, and the converting circuit side and the DC output side of the opening / closing means. An opening / closing signal output unit that detects each DC voltage and outputs a signal that closes the opening / closing unit in the open state when the voltage values are equal to or higher than a predetermined value and the polarities match. Power regeneration device. 2. The power regenerator according to claim 1, further comprising a capacitor which is inserted between the DC side of the conversion circuit and the positive and negative electrodes between the switching means and which smoothes the DC, and which receives an AC input from an AC power supply. An electric power regeneration device, which is configured to be connectable to a DC input side of the inverter unit in an inverter device including a converter unit for converting to DC and an inverter unit for inversely converting the DC to AC and outputting to an AC motor. .