JP2010178570A - Overcharge protection device during regeneration - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To attain a protection circuit during regeneration with simple circuitry, and to ensure safety of the peripheral devices without generating unwanted radio waves, radiation, or the like, for the peripheral devices. <P>SOLUTION: A voltage division circuit 30 divides the voltage between the plus and minus sides of a power supply 11 using a secondary battery. A comparison circuit 33 compares the divided voltage from the voltage division circuit 30 with a reference voltage, and obtains a control signal when the divided voltage exceeds a predetermined value. A first switch circuit 40 short-circuits between the plus and minus terminals of the power supply 11 in response o the control signal. A second switch circuit 12 turns off between the plus terminal and the plus side of the power supply in response to the short-circuit operation thus stopping overcharge. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an overcharge protection device during regeneration, and is an apparatus that is effective when applied to an electric power device such as an electric vehicle driven by an assembled battery, an electric tool, an electric crane, and an electric forklift.

  An electric vehicle driven by a motor using a secondary battery as a power source has been developed. When the electric vehicle slows down or goes down a hill, the motor is switched to a generator, and the secondary battery is charged by the regenerative circuit. In this case, if the secondary battery is overcharged, the battery may be deteriorated or destroyed. In order to improve such a problem, a proposal for absorbing regenerative energy has also been made (Patent Document 1). In the technique of this document, when the voltage of a single cell is measured and the battery is fully charged, the terminal voltage is discharged in the form of current to the primary side on the transformer side by switching so that the voltage of this single cell does not become an overvoltage. Yes. The voltage generated on the secondary side of the transformer is used as regenerative energy. The switching frequency is changed according to the value of the terminal voltage, and the current discharge amount is adjusted.

JP 2005-229787 A

  It is an object of the present invention to provide an overcharge protection device during regeneration that can realize a protection circuit with a simple circuit and can ensure the safety of peripheral devices without causing unnecessary radio waves and unnecessary radiation to the peripheral devices. And

In order to solve the above problems, an embodiment of the present invention
A voltage dividing circuit for dividing the voltage between the plus and minus of the power source using the secondary battery;
A positive terminal and a negative terminal that output a positive / negative voltage of the power source;
A comparison circuit having a hysteresis characteristic that compares a divided voltage of the voltage dividing circuit with a reference voltage, and obtains a control signal when the divided voltage exceeds a predetermined value;
A first switch circuit for short-circuiting between the positive terminal and the negative terminal in response to the control signal;
In response to the first switch circuit forming the short circuit state, a second switch circuit for turning off between the plus terminal and the plus of the power source.

  According to the apparatus of the present invention, a protection circuit can be realized with a simple circuit, and safety of the peripheral device can be achieved without generating unnecessary radio waves and unnecessary radiation to the peripheral device.

It is a figure which shows the structural example of Example 1 of this invention.

  Hereinafter, embodiments of the present invention will be described in detail. FIG. 1 shows an embodiment of the present invention. 11 is a power supply. The power source 11 is configured as an assembled battery in which a plurality of unit cells 11a, 11b,. The voltage between the plus and minus of the power supply 11 is divided by the voltage dividing circuit 30. The voltage dividing circuit 30 is constituted by a series circuit of resistors 31 and 32, for example.

  Further, the positive electrode on the positive voltage side of the power supply 11 is led to the positive terminal 13 via the line L1. A relay switch 12 is connected between the plus terminal 13 and the plus electrode of the power source 11. Further, the negative electrode on the negative voltage side of the power supply 11 is led to the negative terminal 14 via the line L2.

  The divided voltage derived from the voltage dividing circuit 30 is supplied to one input terminal of the comparison circuit 33. The regenerative reference voltage REF is supplied from the terminal 34 to the other input terminal of the comparison circuit 33. The comparison circuit 33 has a hysteresis characteristic, and obtains a control signal that becomes, for example, a high level when the divided voltage exceeds the reference voltage.

  This control signal is supplied to the switch circuit 40. The switch circuit 40 includes, for example, an NMOS transistor 35 to which a control signal is supplied to the source electrode and the gate electrode. The drain electrode of the transistor 35 is connected to the line L2. The NMOS transistor 36 is in a current mirror relationship with the transistor 35. The source of the transistor 36 is connected to the positive terminal 13 via the resistor 37, the drain electrode is connected to the line L2, and the gate electrode is the gate electrode of the previous transistor 35. It is connected to the.

  The PMOS transistor 38 has a source electrode connected to the positive terminal 13 side, a drain electrode connected to the negative terminal 14 side, and a gate electrode connected to the source electrode of the previous transistor 36. Therefore, when the transistors 35 and 36 are turned on, the transistor 38 is also turned on, and the plus terminal 13 and the minus terminal 14 can be short-circuited.

  The relay switch 12 as a switch circuit is turned off when the transistor 38 is turned on, and the relay switch 12 is turned on when the transistor 38 is turned off.

  When the relay switch 12 is turned on and the motor 23 is in the driving mode, the plus / minus voltage of the power source 11 is supplied to the converter 21. The output of the converter 23 is supplied to the motor 23. When the motor 23 does not need to be driven by electricity and can be used as a generator, the regeneration mode is set. That is, the power generation output of the motor 23 is rectified by the converter 23 switched to the rectifier circuit and supplied between the terminals 13 and 14 to charge the assembled battery of the power source 11.

  Here, it is set so that the output of the comparison circuit 33 is inverted when the power supply 11 is fully charged. That is, a control signal is output from the comparison circuit 33. By this control signal, the transistor 38 is turned on, the terminals 13 and 14 are short-circuited, and the relay switch 12 is turned off.

  Thereby, the overcharge of the regenerative energy with respect to the power supply 11 is prevented. Therefore, deterioration and destruction of the secondary battery can be prevented. Further, by controlling the operation of the converter 23, it is possible to obtain a more efficient brake function.

  In addition to forcibly turning off the positive terminal and the positive of the power supply in response to the first switch circuit 40 forming the short circuit state, the relay switch 12 is given from a separate system in the on state. On / off control is also performed in response to the control signal. Thereby, it is also possible to control power supply / stop to the motor 23.

  According to the above-described apparatus, a remarkable effect is exhibited at a construction site where a large number of cranes and the like are controlled using radio in the vicinity. This is because a protection circuit can be realized with a simple circuit, and unnecessary radio waves and unnecessary radiation are not generated for peripheral devices. Circuits that generate unwanted radiation have a significant impact on nearby radio control equipment and may cause accidents. However, with the device of the present invention, it is possible to eliminate such an accident factor.

  The present invention is applicable to electric power devices such as an electric vehicle, an electric tool, and an electric crane driven by a battery pack.

DESCRIPTION OF SYMBOLS 11 ... Power supply, 12 ... Relay circuit, 30 ... Comparison circuit, 40 ... Switch circuit, 21 ... Converter.

Claims (2)

A voltage dividing circuit for dividing the voltage between the plus and minus of the power source using the secondary battery;
A positive terminal and a negative terminal that output a positive / negative voltage of the power source;
A comparison circuit having a hysteresis characteristic that compares a divided voltage of the voltage dividing circuit with a reference voltage, and obtains a control signal when the divided voltage exceeds a predetermined value;
A first switch circuit for short-circuiting between the positive terminal and the negative terminal in response to the control signal;
An overcharge during regeneration, comprising: a second switch circuit that turns off the plus terminal and the plus of the power supply in response to the first switch circuit forming the short circuit state. Protective device. The second switch circuit includes:
In response to the first switch circuit forming the short-circuit state, in addition to forcibly turning off the positive terminal and the positive of the power source, the control circuit also responds to a control signal given from another system in the on-state. 2. The overcharge protection circuit according to claim 1, wherein the overcharge protection circuit is on / off controlled.

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