JP2009159718A - Method for detecting abnormality of transformer, and charger for use therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for surely detecting abnormality of a transformer using a simple constitution, and to provide a charger used therein. <P>SOLUTION: Connection of a battery to be charged to a charger body is detected, an AC current from a commercial power supply is rectified by a rectifier circuit, provided to the primary of a transformer and is smoothed by a smoothing circuit to produce a DC current; the DC current smoothed by a smoothing circuit on the primary is fed alternately to a first winding and a second winding of a transformer, formed by sandwiching a center tap by a switching circuit and transmitted as a high frequency AC current to the secondary of the transformer; the AC current transmitted through the transformer is rectified by a rectifier circuit, provided to the secondary of the transformer and is smoothed by a smoothing circuit before being applied as a charging DC current to a switching-type charging method for charging a battery; the waveform of the charging DC current smoothed by a smoothing circuit provided to the secondary is detected, and charging is stopped when a ripple is detected in the waveform. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a transformer abnormality detection method for detecting abnormality of a center tap type transformer in a switching charging method (push-pull method, full bridge method) and a charger used therefor.

  Patent Document 1 discloses a charging system that can notify a charger failure during charging. This charging system detects the temperature of the battery and determines an abnormality of the charger. However, since the charging system of Patent Document 1 only detects an error in temperature abnormality, it cannot know which part of the charger is abnormal.

JP 2007-280873 A

  The present invention is based on the above prior art, and in a switching charger using a center tap type transformer, the transformer abnormality can be reliably detected with a simple configuration and method. An object of the present invention is to provide a detection method and a charger used therefor.

  In order to achieve the above object, in the invention of claim 1, it is detected that a battery to be charged is connected to the charger body, and an AC current from a commercial power source is rectified by a rectifier circuit provided on the primary side of the transformer, Furthermore, the direct current smoothed by the smoothing circuit is converted into a direct current, and the direct current smoothed by the smoothing circuit on the primary side is applied to the first winding and the second winding formed by sandwiching the center tap of the transformer by the switching circuit. Alternating current is transmitted to the secondary side of the transformer as a high-frequency alternating current, and the alternating current transmitted through the transformer is rectified by a rectifier circuit provided on the secondary side of the transformer, and further smoothed by a smoothing circuit. Applied to a switching type charging method for charging the battery as a direct current for charging, detecting a waveform of the direct current for charging smoothed by a smoothing circuit provided on the secondary side, Trans anomaly detection method of ripple, characterized in that the charging is stopped upon detecting the.

  In the invention of claim 2, in the invention of claim 1, the detection of the waveform of the direct current for charging is a weak current for confirming the connection immediately after the battery is connected to the charger body. It is characterized in that it is performed while a search current is flowing or during charging of the battery.

  According to a third aspect of the invention, in the first or second aspect of the invention, the temperature of the charger main body is detected, and when the temperature of the charger main body reaches a predetermined temperature, the waveform of the DC current for charging is detected. It is characterized by being performed.

  According to a fourth aspect of the present invention, there is provided a charger used in the transformer abnormality detection method according to any one of the first to third aspects, wherein the DC current waveform for charging is detected in the charger body. And a microcomputer for stopping the charging based on a detection result of the waveform detection apparatus.

  According to a fifth aspect of the invention, in the fourth aspect of the invention, a temperature detection device is attached to the surface of the charger main body or a heat generating component constituting the charger main body, and a measurement result by the temperature detection device can be transmitted to the microcomputer. It is characterized by being.

  According to the first aspect of the present invention, the charging DC current waveform smoothed by the smoothing circuit is detected, and charging is stopped when the ripple waveform is detected, so that abnormal heating of the charger main body during charging is prevented. Later secondary disasters can also be prevented. In the switching type charging method, when the first winding and the second winding formed across the center tap of the transformer have an imbalance such as different number of windings or impedance, or the material of the core If there is a misalignment and a bias is generated, the load is biased in one of the first winding and the second winding, and the amount of power generation also changes. This phenomenon is particularly remarkable in a large-capacity transformer. If this is left unattended, the temperature of the charger main body becomes abnormally high, and the equipment constituting the charger main body may be damaged by the heat. In order to prevent this, charging is stopped when the ripple is detected in the waveform that should have been rectified and smoothed on the secondary side, and the above-described effect is obtained. Moreover, by detecting the ripple waveform, it is possible to determine the failure location of the charger main body as a transformer, and it is possible to specify the repair location of the charger main body thereafter, which is beneficial.

  According to the invention of claim 2, the detection of the waveform of the direct current for charging is performed while a search current, which is a weak current for confirming the connection, is passed immediately after the battery is connected to the charger body. Therefore, it is possible to detect abnormalities in the transformer before starting charging the battery, prevent abnormal heat generation during charging in advance, prevent equipment damage, and ensure subsequent secondary disasters Can be prevented. Further, the present invention can be applied to a case where the transformer is deteriorated and becomes abnormal while charging the battery.

  According to the invention of claim 3, the temperature of the charger main body is detected, and when the temperature of the charger main body reaches a predetermined temperature, the waveform of the direct current for charging is detected. For this reason, since the ripple waveform is detected while detecting the temperature of the charger body, charging can be stopped before the device is damaged due to abnormal heat generation. This temperature may be detected by detecting the amount of change in temperature (ΔT) with respect to time, detecting a ripple waveform when there is a sudden rise in temperature, detecting abnormalities in the transformer, and stopping charging. Good.

  According to the fourth aspect of the present invention, the ripple detection waveform of the direct current for charging can be reliably detected by the waveform detection device, and the charging can be reliably stopped by the microcomputer when this ripple waveform is detected. For this reason, abnormality of a transformer can be detected, abnormal heat generation during charging can be prevented, and subsequent secondary disaster can also be prevented.

  According to the fifth aspect of the present invention, the temperature of the charger main body can be reliably detected by the temperature detection device, and the microcomputer can reliably stop charging by detecting the temperature measurement result and the ripple waveform. Thus, abnormal heat generation during charging can be prevented, and subsequent secondary disasters can also be prevented.

  The present invention detects that a battery to be charged is connected to the charger body, rectifies the AC current from the commercial power source with a rectifier circuit provided on the primary side of the transformer, and further smoothes it with a smoothing circuit to obtain a DC current. The DC current smoothed by the smoothing circuit on the primary side is alternately supplied to the first winding and the second winding formed by sandwiching the center tap of the transformer in the switching circuit to obtain the high-frequency AC current. The AC current transmitted to the secondary side of the transformer is rectified by a rectifier circuit provided on the secondary side of the transformer, and further smoothed by a smoothing circuit to be supplied to the battery as a direct current for charging. This is applied to the switching type charging method for charging, detects the waveform of the direct current for charging smoothed by the smoothing circuit provided on the secondary side, and charges when the ripple is detected in the waveform. A charger for use in the detection method and this transformer anomaly stop.

  FIG. 1 is a flowchart of a transformer abnormality detection method according to the present invention.

Step S1:
A battery is connected to the output terminal of the charger body.

Step S2:
When the battery is connected in step S1, a search current, which is a slight current (weak current) for obtaining information such as whether this connection is securely made, is supplied. At this time, the battery voltage is also checked. This check is performed by, for example, a voltage sensor provided in the charger body.

Step S3:
Detects whether ripples are generated in the search current waveform rectified and smoothed on the secondary side of the transformer.

Step S4:
If a ripple waveform is detected in step S3, charging is stopped. This makes it possible to detect abnormalities in the transformer before starting charging the battery, prevent abnormal heat generation during charging in advance, prevent damage to the equipment, and reliably prevent subsequent secondary disasters. can do.

Step S5:
When no ripple is generated in the search current, charging of the battery is started.

Step S6:
It detects whether the charger body has reached a predetermined temperature during charging. The predetermined temperature may be set to a high temperature that does not reach during normal charging, or may be detected as whether or not the amount of change in temperature (ΔT) with respect to time is equal to or greater than a predetermined value.

Step S7:
If the charger main body has reached the predetermined temperature in step S6, it is detected whether or not a ripple is generated in the waveform of the charging current rectified and smoothed on the secondary side of the transformer. If the ripple waveform is detected, it is determined that the transformer is abnormal, and the process returns to step S4 to stop charging. As a result, the ripple waveform can be detected when there is a sudden temperature rise, and the abnormality of the transformer can be detected to stop charging. This detection is effective when an abnormality occurs in the transformer during charging. The reason why the abnormality of the transformer is not determined only by the temperature parameter is that the temperature may reach a predetermined temperature even when the outside air temperature is high, for example.

Step S8:
If the charger main body has not reached the predetermined temperature in step S6 or no ripple waveform is detected in step S7, it is determined whether or not the battery is fully charged. If the battery has not reached full charge, the process returns to step S5 to continue charging.

Step S9:
If the full charge is confirmed in step S8, the charging is finished.

  FIG. 2 is a schematic configuration diagram of a charger used in the transformer abnormality detection method according to the present invention.

  The charger used in the rapid charging method according to the present invention includes a charger body 1 having an input terminal 2 and an output terminal 3. The input terminal 2 and the output terminal 3 are connected via a transformer 4. The primary side of the transformer 4 includes a filter circuit 5, a bridge diode (primary side rectifier circuit) 6, capacitors (primary side smoothing circuits) 7 a and 7 b, resistance members 8 a and 8 b, and a switching circuit 9. On the secondary side of the transformer 4, a rectifier circuit 10, a smoothing circuit 11, and an output circuit 12 are provided. On the other hand, the charger main body 1 includes an internal power supply circuit 13 and a microcomputer 14. A battery (not shown) to be charged is connected to the output terminal 3. The input terminal 2 is connected to a commercial power source (not shown).

  When charging the battery, the power supplied from the input terminal 2 is filtered through the filter circuit 5, and the current is alternately stored in the two capacitors 7a and 7b. At this time, since the ground side passes through the bridge diode 6, the current stored in the capacitors 7a and 7b is DC. The current stored in the capacitors 7 a and 7 b flows to the midpoint of the primary winding of the transformer 4. That is, the transformer 4 is a center tap type, and is formed by the first winding 4a and the second winding 4b.

  On the other hand, the supply power from the input terminal 2 is also supplied to the internal power supply circuit 13. The internal power supply circuit 13 is for securing a power supply in the charger body 1 and is connected to the switching circuit 13 and the microcomputer 14.

  The switching circuit 9 alternately causes a current to flow through the first winding 4a and the second winding 4b from the middle point of the transformer 4 for a predetermined time (in the directions of arrows A and B). The switching circuit 9 is a gate drive circuit such as an FET, and switches the direction in which a current flows from the middle point of the transformer 4 every predetermined time when a voltage is applied to the gate.

  With the above action, the power supply voltage (current) is converted into an output voltage for charging (high-frequency alternating current) by the transformer 4 and rectified by the rectifier circuit 10 provided on the secondary side of the transformer 4. The voltage (current) rectified in this way is smoothed by the smoothing circuit 11 and becomes a direct current for charging, and the battery is charged from the output circuit 12 via the output terminal 3. At this time, the microcomputer 14 determines the amount of charge while observing the voltage of the battery connected to the output terminal 3. The microcomputer 14 is a control circuit for controlling, for example, voltage and current with respect to the output terminal 3.

  The microcomputer 14 includes (built in) a waveform detection device 15. The waveform detector 15 detects a waveform of a direct current for charging that has been rectified by the rectifier circuit 10 on the secondary side of the transformer 4 and smoothed by the smoothing circuit 11. Since the charging current rectified and smoothed by the rectifying circuit 10 and the smoothing circuit 11 is a direct current, the waveform should be a straight line. However, if an imbalance such as the number of windings or impedance is different between the first winding 4a and the second winding 4b of the transformer, or the core material of the winding of the transformer 4 is wrongly inserted. When the magnetic bias is generated, the load is biased in one of the first winding 4a and the second winding 4b, and the power generation amount is also changed. If left untreated, the temperature of the charger main body 1 becomes very high, and the equipment constituting the charger main body 1 may be damaged by the heat. In such a case, a ripple close to noise occurs in the waveform described above. The waveform detector 15 detects this ripple waveform. When the ripple waveform is detected, the microcomputer 14 stops charging. Thereby, the damage by the abnormal heat generation of the charger main body due to the abnormality of the transformer and the secondary disaster caused by this can be prevented.

  A temperature detector 16 is attached to the switching circuit 9. The temperature measured by the temperature detector 16 is transmitted to the microcomputer 14. The temperature detection device 16 detects the temperature of the switching circuit 9 and uses the detection result in the above-described abnormality detection method for the transformer 4. That is, when the switching circuit 9 suddenly generates heat during charging, an imbalance occurs in the first winding 4a and the second winding 4b of the transformer 4 due to deterioration of the transformer 4 over time or changes in the insulation of the coil. Therefore, the ripple waveform can be detected by the waveform detector 15 based on the temperature measurement result, and the abnormality of the transformer 4 can be detected. The temperature detection by the temperature detection device 16 is based on whether or not the switching circuit 9 has reached a high temperature that cannot be reached during normal charging, or whether or not the amount of change in temperature (ΔT) with respect to a predetermined time is greater than or equal to a predetermined value. Any item may be detected. It should be noted that the temperature detection device 16 determines that an abnormality has occurred and before intentionally moving to the detection of the ripple waveform, it is intentionally used with a stress sufficiently lower than the rating of the element (for example, low) for the purpose of reducing the failure rate of each element. Derating may be performed. By detecting the ripple waveform during the derating, it is possible to prevent the charger main body from being damaged due to abnormal heat generation during the detection of the ripple waveform.

  The location where the temperature detection device 16 is installed covers not only each element constituting the switching circuit 9 but also the surface of the heat generating component such as a rectifier diode, a bridge diode, a transformer, a choke coil, or a line filter, its periphery, or these. You may attach to the surface of a case. Regardless of the temperature measured at any location, it is possible to detect an abrupt temperature rise of the charger body 1 and detect a ripple waveform to detect an abnormality in the transformer. In particular, if a temperature detection device is attached to a place where heat is most likely to be generated, damage to the charger body due to temperature rise can be prevented more reliably.

It is a flowchart of the abnormality detection method of the transformer which concerns on this invention. It is a schematic block diagram of the charger used for the abnormality detection method of the transformer concerning this invention.

Explanation of symbols

1: Charger body, 2: Input terminal, 3: Output terminal, 4: Transformer, 4a: First winding, 4b: Second winding, 5: Filter circuit, 6: Bridge diode, 7a, 7b: Capacitor, 8a, 8b: resistance member, 9: switching circuit, 10: rectifier circuit, 11: smoothing circuit, 12: output circuit, 13: internal power supply circuit, 14: microcomputer, 15: waveform detection device, 16: temperature detection device

Claims (5)

Detect that the battery to be charged is connected to the charger body,
AC current from the commercial power source is rectified by a rectifier circuit provided on the primary side of the transformer, and further smoothed by a smoothing circuit to obtain a DC current.
A direct current smoothed by the smoothing circuit on the primary side is alternately passed through a first winding and a second winding formed by sandwiching a center tap of the transformer in a switching circuit, and the transformer is converted into a high-frequency alternating current. To the secondary side of the
Applied to a switching type charging method in which the alternating current transmitted through the transformer is rectified by a rectifier circuit provided on the secondary side of the transformer and then smoothed by a smoothing circuit to charge the battery as a direct current for charging. And
Detecting the waveform of the direct current for charging smoothed by the smoothing circuit provided on the secondary side,
A transformer abnormality detection method, wherein charging is stopped when a ripple is detected in the waveform.   The detection of the waveform of the direct current for charging is performed while a search current, which is a weak current for confirming the connection immediately after the battery is connected to the charger body, or during charging of the battery. The transformer abnormality detection method according to claim 1, wherein the transformer abnormality detection method is performed.   The temperature of the charger main body is detected, and when the temperature of the charger main body reaches a predetermined temperature, the detection of the waveform of the direct current for charging is performed. Transformer abnormality detection method. A charger used in the transformer abnormality detection method according to any one of claims 1 to 3,
In the charger body, equipped with a waveform detection device for detection of the waveform of the direct current for charging,
The charger provided with the microcomputer for stopping the said charge based on the detection result of the said waveform detection apparatus.   5. The charging according to claim 4, wherein a temperature detection device is attached to a surface of the charger main body or a heat generating component constituting the charger main body, and a measurement result by the temperature detection device can be transmitted to the microcomputer. vessel.

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