Passive discharge circuit for forklift driver

Abstract

The utility model discloses a passive discharge circuit for a forklift driver. The passive discharge circuit is characterized by comprising a first resistor, a second resistor, a first capacitor, an isolation optocoupler, a third resistor, a second capacitor, a fourth resistor, a third capacitor, a PNP type triode, a voltage-regulator tube, a fifth resistor, a sixth resistor, a fourth capacitor, an NMOS tube and a seventh resistor. The utility model has the advantages that the power failure requirement is met through the passive discharge hardware circuit, the overall temperature rise is little in the working process, the safety accident caused by the temperature rise of the device is reduced, and the use is safer; and small-size devices are used, so that the size of the whole circuit is small, the area occupied by the components on the circuit board is reduced, and the installation is convenient.

Description

Technical Field

[0001] The utility model relates to a passive discharge circuit, in particular to a passive discharge circuit used for a forklift driver. Background Art

[0002] In order to achieve high voltage safety, the high voltage should be turned off immediately after the forklift key is turned off to avoid electric shock accidents caused by direct or indirect contact between personnel and high voltage live parts. However, in the discharge circuit used by forklift drivers on the market, the discharge resistor is directly connected to the positive and negative terminals of the busbar energy storage capacitor for discharge, but a high-power discharge resistor is required, which is large in size and occupies space. In addition, the discharge resistor heats up severely over a long period of time and is easily damaged, posing a safety hazard. Summary of the invention

[0003] The technical problem to be solved by the utility model is to provide a passive discharge circuit for a forklift driver, which is not only small in size but also has improved safety.

[0004] The utility model solves the above technical problems by adopting the following technical solution: a passive discharge circuit for a forklift driver, comprising a first resistor, a second resistor, a first capacitor, an isolation optical coupler, a third resistor, a second capacitor, a fourth resistor, a third capacitor, a PNP transistor, a voltage regulator, a fifth resistor, a sixth resistor, a fourth capacitor, an NMOS tube and a seventh resistor.

[0005] One end of the first resistor is connected to the output end of the external first power module, the other end of the first resistor, one end of the second resistor, one end of the first capacitor are connected to the first pin of the isolation optocoupler, the other end of the second resistor, the other end of the first capacitor and the second pin of the isolation optocoupler are connected to the power ground of the external first power module, the fourth pin of the isolation optocoupler, one end of the third resistor, one end of the second capacitor, one end of the fourth resistor, one end of the third capacitor are connected to the emitter of the PNP transistor, the other end of the fourth resistor, the other end of the third resistor, the base of the PNP transistor and one end of the voltage regulator are connected, the collector of the PNP transistor is connected to one end of the fifth resistor, the other end of the fifth resistor, one end of the sixth resistor, one end of the fourth capacitor are connected to the gate of the NMOS tube, the drain of the NMOS tube is connected to one end of the seventh resistor, the other end of the third resistor and the other end of the seventh resistor are connected to the output end of the external second power module,

[0006] The third pin of the isolation optocoupler, the other end of the second capacitor, the other end of the voltage regulator, the other end of the sixth resistor, the other end of the fourth capacitor and the source of the NMOS tube are connected to the power ground of the external second power module, and the external first power module is isolated from the external second power module.

[0007] The isolation optocoupler is a high-speed isolation optocoupler, which reduces the switching time delay.

[0008] The seventh resistor is a PTC resistor. The resistance of the PTC resistor increases with the increase of temperature, which can protect the circuit from overcurrent and increase the service life of the resistor.

[0009] Compared with the prior art, the utility model has the advantages that when the key is turned on, the external first power module is turned on, and after the first resistor voltage division, the first foot, the second foot, the third foot and the fourth foot of the isolation optical coupler are all turned on, at this time, the level of the fourth foot of the isolation optical coupler is pulled down, the PNP type transistor is cut off, the gate of the NMOS tube is turned off, and the entire passive discharge circuit is in a closed state; when the key is turned off, the external first power module is turned off, the first foot, the second foot, the third foot and the fourth foot of the isolation optical coupler are all disconnected, and the voltage output by the external second power module is connected to the emitter of the PNP type transistor through the third resistor voltage division, and the voltage regulator tube provides power. The voltage output by the external second power module is quickly powered off through the seventh resistor and the NMOS tube to complete the discharge. Surges may exist in the circuit, and the NMOS tube has a higher withstand voltage. The utility model achieves the power-off requirement through a passive discharge hardware circuit. During the working process, the overall temperature does not rise much, which reduces the safety accidents caused by the temperature rise of the device and is safer to use. Small-volume devices are used to make the volume of the entire circuit smaller, reduce the area of ​​the circuit board occupied by components, and facilitate installation. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 This is a circuit structure schematic diagram of the utility model. Implementation

[0011] The present invention will be described in further detail below in conjunction with the accompanying drawings.

[0012] like Figure 1As shown, a passive discharge circuit for a forklift driver includes a first resistor R1, a second resistor R2, a first capacitor C1, an isolation optical coupler PC, a third resistor R3, a second capacitor C2, a fourth resistor R4, a third capacitor C3, a PNP transistor Q1, a voltage regulator ZD, a fifth resistor R5, a sixth resistor R6, a fourth capacitor C4, an NMOS transistor Q2 and a seventh resistor R7; the isolation optical coupler PC is a high-speed isolation optical coupler; the seventh resistor R7 is a PTC resistor; the voltage regulator ZD has a regulated power supply of 10-15V;

[0013] One end of the first resistor R1 is connected to the output end KEY of the external first power module, the other end of the first resistor R1, one end of the second resistor R2, one end of the first capacitor C1 and the first pin of the isolation optocoupler PC are connected, the other end of the second resistor R2, the other end of the first capacitor C1 and the second pin of the isolation optocoupler PC are connected to the power ground GND-KEY of the external first power module, the fourth pin of the isolation optocoupler PC, one end of the third resistor R3, one end of the second capacitor C2, one end of the fourth resistor R4, one end of the third capacitor C3 and the emitter of the PNP transistor Q1 are connected, and the fourth resistor R3 is connected to the output end KEY of the external first power module. The other end of R4, the other end of the third resistor R3, the base of the PNP transistor Q1 and one end of the voltage regulator ZD are connected, the collector of the PNP transistor Q1 is connected to one end of the fifth resistor R5, the other end of the fifth resistor R5, one end of the sixth resistor R6, one end of the fourth capacitor C4 and the gate of the NMOS transistor Q2 are connected, the drain of the NMOS transistor Q2 is connected to one end of the seventh resistor R7, the other end of the third resistor R3 and the other end of the seventh resistor R7 are connected to the output end VEE of the external second power module, and the output end VEE of the external second power module is in a low level input mode;

[0014] The third pin of the isolation optical coupler PC, the other end of the second capacitor C2, the other end of the voltage regulator tube ZD, the other end of the sixth resistor R6, the other end of the fourth capacitor C4 and the source of the NMOS tube Q2 are connected to the power ground GND of the external second power module, and the external first power module is isolated from the external second power module;

[0015] The working principle of this embodiment is as follows: when the key is turned on, the external first power module is turned on, and after the voltage is divided by the first resistor R1, the 1st, 2nd, 3rd and 4th pins of the isolation optocoupler PC are all turned on. At this time, the level of the 4th pin of the isolation optocoupler PC is pulled down, the PNP transistor Q1 is cut off, the gate of the NMOS tube Q2 is turned off, and the entire passive discharge circuit is in a closed state; when the key is turned off, the external first power module is turned off, the 1st, 2nd, 3rd and 4th pins of the isolation optocoupler PC are all disconnected, and the voltage output by the external second power module is connected to the emitter of the PNP transistor Q1 after the voltage is divided by the third resistor R3, and the voltage regulator ZD provides a voltage to the base of the PNP transistor Q1. At this time, the PNP transistor Q1 is turned on, the gate of the NMOS tube Q2 is opened, and the entire passive discharge circuit is in an open state. The voltage output by the external second power module is quickly powered off through the seventh resistor R7 and the NMOS tube Q2 to complete the discharge.

Claims

1. A passive discharge circuit for a forklift driver, characterized in that It includes a first resistor, a second resistor, a first capacitor, an isolation optical coupler, a third resistor, a second capacitor, a fourth resistor, a third capacitor, a PNP transistor, a voltage regulator, a fifth resistor, a sixth resistor, a fourth capacitor, an NMOS transistor and a seventh resistor, One end of the first resistor is connected to the output end of the external first power module, the other end of the first resistor, one end of the second resistor, one end of the first capacitor are connected to the first pin of the isolation optocoupler, the other end of the second resistor, the other end of the first capacitor and the second pin of the isolation optocoupler are connected to the power ground of the external first power module, the fourth pin of the isolation optocoupler, one end of the third resistor, one end of the second capacitor, one end of the fourth resistor, one end of the third capacitor are connected to the emitter of the PNP transistor, the other end of the fourth resistor, the other end of the third resistor, the base of the PNP transistor and one end of the voltage regulator are connected, the collector of the PNP transistor is connected to one end of the fifth resistor, the other end of the fifth resistor, one end of the sixth resistor, one end of the fourth capacitor are connected to the gate of the NMOS tube, the drain of the NMOS tube is connected to one end of the seventh resistor, the other end of the third resistor and the other end of the seventh resistor are connected to the output end of the external second power module, The third pin of the isolation optocoupler, the other end of the second capacitor, the other end of the voltage regulator, the other end of the sixth resistor, the other end of the fourth capacitor and the source of the NMOS tube are connected to the power ground of the external second power module, and the external first power module is isolated from the external second power module.

2. A passive discharge circuit for a forklift driver according to claim 1, characterized in that The isolation optocoupler is a high-speed isolation optocoupler.

3. A passive discharge circuit for a forklift driver according to claim 1, characterized in that The seventh resistor is a PTC resistor.

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