JP2006296096A - Regenerative resistor protection device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a regenerative resistor protection device whose regenerative capability is not affected by working conditions or surrounding environments, that makes it unnecessary to use an electromagnetic contactor or a fuse of large capacity, and that is cost effective and least affected by malfunction. <P>SOLUTION: This regenerative resistor protection device is provided with an abnormality detection means 2 that detects an abnormality of a regenerative power absorption circuit 1 that absorbs regenerative power generated from an inverter circuit 10 connected between DC bus bars, and a switching element control means 3 that stops conducting the regenerative power absorption circuit 1 with the abnormal signal detected by the abnormality detection means 2. The regenerative power absorption circuit 1, which is connected in series to a regenerative resistor 4 that absorbs the regenerative power, consists of a first semiconductor-switching element 5 that controls the conduction to the regenerative resistor 4 and a second semiconductor-switching element 6. In the normal operation, one of the semiconductor-switching elements is set to an open state, and the other to a closed one. If an abnormal signal is received, a switching element control means 3 controls the two semiconductor switching elements 5, 6 forcibly to the open state to stop conducting the regenerative resistor 4. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a protection device for a regenerative resistor connected to an inverter circuit of a motor drive device that drives a servo motor or the like.

  Conventionally, when a switching element of a regenerative power absorption circuit connected to an inverter circuit fails, the regenerative resistor is always energized, leading to burnout of the regenerative resistor. In order to prevent this, there is a method of selecting the resistance of the resistor so that the resistor is melted during normal energization.

  In addition, the temperature of the regenerative resistor is detected by the temperature detector, and the power supply is cut off if the temperature becomes abnormally high. A temperature fuse is connected in series with the regenerative resistor, and the temperature of the regenerative resistor is abnormally high. There is a method to set the fuse to blow when it becomes.

Further, a method has been devised in which a large-capacity current fuse is connected in series to the regenerative resistor, and the current fuse is forcibly operated by a thyristor in a separate circuit from the regenerative resistor when an abnormality is detected (for example, (See Patent Document 1).
JP-A-5-336758

  The problem to be solved is that it is difficult to select the resistance of the resistor that absorbs the regenerative power.To select the resistor so that it does not melt for a long time under normal use conditions, the ambient temperature It was necessary to consider the usage environment, etc., and there was a problem in the tolerance selection.

  In addition, if the power supply is cut off by detecting the temperature abnormality of the regenerative resistor, it is necessary to cut off the power supply of the main circuit, so a large-capacity electromagnetic contactor, etc. is required, which has a problem in terms of price. .

  Also, in the case where a thermal fuse is connected in series to the regenerative resistor described above, it is necessary to cut the DC current, so a contact type fuse is not suitable for use, and an alloy type thermal fuse has a limit in operating temperature. If the capacity of the regenerative resistor itself is increased and the temperature rise is not suppressed, the required regenerative ability cannot be obtained and there is a problem.

  In addition, the method of forcibly cutting the fuse with a thyristor in the event of an abnormality requires a large current fuse for DC interruption, and if the thyristor is accidentally fired for some reason, the current fuse is blown instantly, so the current fuse Had to be replaced.

  The present invention solves the above-mentioned conventional problems, the regenerative ability is not affected by the use conditions and the surrounding environment, it is not necessary to use a large-capacity electromagnetic contactor or fuse, etc. An object is to provide a resistance protection device.

In order to solve the above-described problems, the present invention provides a regenerative power absorption circuit that is connected between DC buses that supply power to an inverter circuit and absorbs regenerative power generated from the inverter circuit, and an abnormality in the regenerative power absorption circuit. An abnormality detection means for detecting; and a switching element control means for stopping energization of the regenerative power absorption circuit by an abnormality signal detected by the abnormality detection means, wherein the regenerative power absorption circuit absorbs the regenerative power. A first semiconductor switching element for controlling energization to the regenerative resistor connected in series, and a second semiconductor switching element connected in series to the regenerative resistor and the first semiconductor switching element. The first semiconductor switching element and / or the second semiconductor switching element is opened by the abnormal signal. It intended to stop the current supply to the regenerative resistor by, protect from being burnout regenerative resistor by the failure of the semiconductor switching element.

  According to the regenerative resistance protection device of the present invention, two semiconductor switching elements are provided in series in the regenerative power absorption circuit, and at least the semiconductor switching element that has not failed is opened. It can stop energization and prevent burning.

  One semiconductor switching element is always closed in a normal state, and the other semiconductor switching element is opened and closed according to the line voltage of the DC bus, thereby reducing the probability of failure of the closed semiconductor switching element. The switching loss can be reduced, and the heat dissipation of the semiconductor switching element can be realized with a simple one.

  In addition, the power source for driving the positive semiconductor switching element is supplied from a capacitor connected through a rectifier element between the positive side of the power source for driving the negative semiconductor switching element and the negative side of the positive semiconductor switching element. Therefore, it is not necessary to configure a new power source, and it can be configured at low cost.

  In this way, it is possible to obtain a regenerative resistance protection device that is less susceptible to the failure of the semiconductor switching element and can reliably protect the regenerative resistor from burning.

  A regenerative power absorption circuit connected between DC buses for supplying power to the inverter circuit and absorbing regenerative power generated from the inverter circuit, an abnormality detection means for detecting an abnormality in the regenerative power absorption circuit, and the abnormality detection means Switching element control means for stopping energization of the regenerative power absorption circuit by an abnormal signal detected by the regenerative power absorption circuit, the regenerative power absorption circuit, and the regenerative resistor connected in series A first semiconductor switching element for controlling energization to the capacitor, and a second semiconductor switching element connected in series to the regenerative resistor and the first semiconductor switching element, and the first semiconductor by the abnormal signal Stop energization to the regenerative resistor by opening the switching element and / or the second semiconductor switching element. That.

  In the first embodiment, a thermal protector is used as an abnormality detection means of the regenerative resistor.

  In FIG. 1, the regenerative power absorption circuit 1 is composed of a series circuit of a regenerative resistor 4, a first semiconductor switching element 5, and a second semiconductor switching element 6. Normally, the point where one semiconductor switching element is connected to the regenerative resistor 4 is that two semiconductor switching elements are connected in series.

  The regenerative power absorption circuit 1 is connected between the DC buses, and when a threshold value described later is exceeded, the first semiconductor switching element 5 and the second semiconductor switching element 6 are closed to absorb the regenerative power.

  The abnormality detection means 2 includes a thermal protector 15 that detects an abnormality in the temperature of the regenerative resistor 4 and an abnormality determination circuit 16 that processes the signal. The abnormality determination circuit 16 outputs an abnormality signal to the switching element control means 3 when an abnormality is detected.

  The switching element control unit 3 receives the output of the abnormality detection unit 2 or the output of the DC voltage detection unit 14 as an input, and the first gate signal generation unit 17 and the second gate voltage generation unit 18 perform the first semiconductor switching. The ON / OFF of the element 5 and the second semiconductor switching element 6 is controlled.

  On the other hand, an inverter circuit 10 is connected between DC buses (positive side 12 and negative side 13) which is rectified by a rectifier 8 and is smoothed by a smoothing capacitor 9 as a main power source of a motor drive device, and upper and lower switching elements. The motor 11 is driven by controlling ON and OFF.

  In general, the DC voltage detection means 14 has two threshold values (a first set voltage value and a second set voltage value), and is connected between the DC buses to monitor changes in the line voltage. The bus voltage information is output to the switching element control means 3.

  Here, the normal operation from the normal operation to the regenerative operation will be described. When the voltage detected by the DC voltage detection means 14 is equal to or lower than the first set voltage value (during normal operation), the first semiconductor switching element 5 is set in the open state and the second semiconductor switching element 6 is set in the closed state. .

  When the DC voltage detected by the DC voltage detection means 14 exceeds the first set voltage value, the first semiconductor switching element 5 is brought into a closed state. As a result, both the first semiconductor switching element 5 and the second semiconductor switching element 6 are closed, and the regenerative resistor 4 is directly connected between the DC buses, and the regenerative resistor 4 absorbs the regenerative power. To do. When the DC voltage becomes smaller than the second set voltage due to absorption of regenerative power, the first semiconductor switching element 5 is returned to the open state during normal operation, and energization to the regenerative resistor 4 is stopped.

  Thus, if the motor 11 is operated in the regeneration region, the regenerative power generated from the inverter circuit 10 can be absorbed normally.

  Next, operations from detection of abnormality in the regenerative power absorption circuit to protection of the regenerative resistor will be described. For example, if the first semiconductor switching element 5 that is normally open is closed due to a short-circuit failure, the second semiconductor switching element is normally closed, so that the regenerative resistor is not in a regenerative operation. When the regenerative resistor 4 reaches a high temperature, an abnormality signal is output from the abnormality determination circuit 16.

  When the switching element control means 3 receives the abnormality signal from the abnormality determination circuit 16, both the first semiconductor switching element 5 and the second semiconductor switch 6 are forcibly set regardless of the voltage information by the DC voltage detection means 14. Since the energization to the regenerative resistor 4 can be stopped by controlling to the open state, the regenerative resistor 4 can be prevented from becoming further hot.

  By the way, in the initial setting, the two semiconductor switching elements can be both opened. However, since the probability of occurrence of a failure increases, it is better to close one of them. Further, the first semiconductor switching element and the second semiconductor switching element can be similarly implemented even if the opening and closing are reversed.

  However, it is usually advantageous to set the second semiconductor switching element in the closed state. This point will be described in detail with reference to FIG.

The second gate signal generating means 18 includes a power source 21 and a second gate circuit 23, and the first gate signal generating means 17 includes a negative side of the first semiconductor switching element 5, a positive side of the power source 21, and the like. Between the capacitor 19 and the first gate circuit 22 as a power source connected through the rectifying element 20.

  Normally, the capacitor 19 is charged from the power source 21 through the second semiconductor switching element 6 by setting the second semiconductor switching element 6 in the closed state. Although the second semiconductor switching element 6 is opened when there is an abnormality, it is not necessary to close the first semiconductor switching element 5 at this time, so no new power source is required for the first gate signal generating means 17 Therefore, it can be configured simply and inexpensively.

  Furthermore, if the second semiconductor switching element 6 is constituted by a MOSFET, the capacitor 19 can be charged to a value obtained by subtracting the voltage drop of the rectifying element 20 from the power source 21 at normal times, and the ON voltage of the second semiconductor switching element 6 is reduced. The influence can be eliminated.

  Also, if the operating temperature of the thermal protector 15 is set appropriately, the regenerative resistor 4 will not generate heat abnormally even if it is used beyond the tolerance of the regenerative resistor 4 as well as the failure of the semiconductor switching element. If the cause of the abnormality can be eliminated, the use can be continued without replacing parts such as the semiconductor switching element.

  The second embodiment detects an abnormality from the current flowing through the regenerative resistor. The second embodiment is the same as the first embodiment except that the configuration of the abnormality detection unit and the signal processing in the switching element control unit are different. Is omitted.

  In FIG. 3, the abnormality detection unit 31 includes a current detection unit 32 and an abnormality determination circuit 33. The current detection means 32 detects the presence or absence of current flowing through the regenerative resistor 4. The switching element control means 34 outputs the switching information signal (open state or closed state) of the first semiconductor switching element 5 to the abnormality determination circuit 33.

  The abnormality determination circuit 33 indicates that an abnormality has occurred in the first semiconductor switching element 5 when there is a current detection value signal even though the switching information signal of the first semiconductor switching element 5 is open. Judgment is made and an abnormal signal is output to the switching element control means 34.

  When the switching element control unit 34 receives the abnormality signal from the abnormality determination circuit 33, both the first semiconductor switching element 5 and the second semiconductor switch 6 are forcibly set regardless of the voltage information by the DC voltage detection unit 14. Control to open state. Thereby, since the electricity supply to the regenerative resistor 4 can be stopped, it can prevent that the regenerative resistor 4 becomes high temperature further.

  The regenerative resistance protection device of the present invention is optimal for a motor drive device that prevents burnout of a regenerative resistor due to a failure of a semiconductor switching element, and is also useful for applications that require a large regenerative capacity and high ambient temperature. It is.

The block block diagram of the motor drive device which has a regeneration resistance protection apparatus in Example 1 of this invention. Explanatory drawing of the regeneration resistance protection apparatus in Example 1 of this invention The block block diagram of the motor drive device which has a regeneration resistance protection apparatus in Example 2 of this invention.

Explanation of symbols

1 regenerative power absorption circuit 2, 31 abnormality detection means 3, 34 switching element control means 4 regenerative resistor 5 first semiconductor switching element 6 second semiconductor switching element 7 AC power supply 8 rectifier 9 smoothing capacitor 10 inverter circuit 11 servo motor 12 DC bus (positive side)
13 DC bus (negative side)
14 DC voltage detection means 15 Thermal protector 16, 33 abnormality determination circuit 17 First gate signal generation means 18 Second gate signal generation means 19 Capacitor 20 Rectifying element 21 Power supply 22 First gate circuit 23 Second gate circuit 32 Current detection means

Claims (3)

A regenerative power absorption circuit connected between DC buses for supplying power to the inverter circuit and absorbing regenerative power generated from the inverter circuit, an abnormality detection means for detecting an abnormality in the regenerative power absorption circuit, and the abnormality detection means Switching element control means for stopping energization of the regenerative power absorption circuit by an abnormal signal detected by the regenerative power absorption circuit, the regenerative power absorption circuit, and the regenerative resistor connected in series A first semiconductor switching element for controlling energization to the capacitor, and a second semiconductor switching element connected in series to the regenerative resistor and the first semiconductor switching element, and the first semiconductor by the abnormal signal Stop energization to the regenerative resistor by opening the switching element and / or the second semiconductor switching element. Regenerative resistor protecting apparatus according to claim Rukoto. The second semiconductor switching element is normally set in a closed state after power-on, and the first semiconductor switching element absorbs regenerative power by being closed when the voltage of the DC bus is high. The regenerative resistance protection device according to claim 1, wherein when an abnormality is detected by the abnormality detection means, the first semiconductor switching element is opened. One of the regenerative resistors is connected to the positive side of the DC bus, one of the first semiconductor switching elements is connected to the other of the regenerative resistors, and the second semiconductor switching element is the other of the first semiconductor switching elements Is connected to the negative side of the DC bus, and the power source driving the first semiconductor switching element is rectified between the negative side of the first semiconductor switching element and the positive side of the power source driving the second semiconductor switching element. The regenerative resistance protection device according to claim 1 or 2, which is supplied by a capacitor connected through the element.

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