Overload and short circuit protection circuit for direct current motor controller of aerial work platform

Abstract

The utility model discloses an overload and short-circuit protection circuit for a direct current motor controller of an aerial work platform, which comprises an overload protection circuit and a short-circuit protection circuit, the current working state of a direct current motor M1 is judged by detecting the working current of the direct current motor M1, and whether the direct current motor M1 is normal, overloaded or short-circuited is distinguished. After the overload protection circuit or the short circuit protection circuit detects that the direct current motor M1 is overloaded or short-circuited, the power supply cathode of the direct current motor M1 is switched to enter a protection state, so that the direct current motor M1 is protected, and the problem that the motor is on fire or burnt out is avoided.

Description

Technical Field

[0001] The utility model belongs to the technical field of direct current motor controllers for aerial work platforms, in particular to an overload and short-circuit protection circuit for direct current motor controllers for aerial work platforms. Background Art

[0002] The aerial work platform DC motor controller provides DC power for the aerial vehicle platform motor. The existing aerial work platform DC motor controller can only provide forward and reverse power for the motor. When the motor is overloaded or short-circuited, it cannot protect the controller and DC motor, which can easily cause fire or burnout. Utility Model Content

[0003] The utility model aims to provide an overload and short-circuit protection circuit for a DC motor controller of an aerial work platform, which can protect the controller and the DC motor when the motor is overloaded or short-circuited.

[0004] To achieve the above-mentioned purpose, the utility model provides an overload and protection circuit for a DC motor controller of an aerial work platform, including an overload protection circuit and a short-circuit protection circuit; the overload protection circuit includes an operational amplifier U1A, the negative input terminal 2 pin of the operational amplifier U1A is connected to the reference voltage REF1 for overload protection, the 8 pin of the operational amplifier U1A is connected to a positive 5V power supply, the 1 pin is divided into two paths, one path is connected to the positive electrode of the diode D1, and the other path is connected to the positive electrode of the diode D3; the negative electrode of the diode D1 is connected to the base of the transistor Q2; the negative electrode of the diode D3 is connected to the positive input terminal 3 pin of the operational amplifier; the 3 pins of the operational amplifier are also connected to the ground through the capacitor C1 and connected to the short-circuit protection circuit through the resistor R3;

[0005] The short-circuit protection circuit includes an operational amplifier U1B, wherein the negative input terminal 6 pin of the operational amplifier U1B is connected to the reference voltage REF2 for short-circuit protection, and the positive input terminal 5 pin of the operational amplifier U1B is respectively connected to the cathode of the diode D4 and one end of the resistor R4; the anode of the diode D4 is connected to the 7 pin of the operational amplifier U1B and to the anode of the diode D2; the other end of the resistor R4 is respectively connected to one end of the resistor R3 and the emitter 2 pin of the transistor Q2; the cathode of the diode D2 is connected to the base 1 pin of the transistor Q2.

[0006] As a further solution of the utility model: the emitter of the transistor Q2 is also grounded through the resistor R1, and the collector pin 3 of the transistor Q2 is divided into two paths, one of which is connected to the pin 4 of the field effect transistor Q1, and the other is connected to one end of the resistor R2; the pin 1 of the field effect transistor Q1 is grounded through the resistor R1, and the pin 5 of the field effect transistor Q1 is connected to one end of the DC motor M1; the other end of the DC motor M1 is respectively connected to the positive electrode of the power supply and the other end of the resistor R2.

[0007] As a further solution of the utility model: the current relationship between the normal operation and overload and short-circuit operation of the DC motor M1 is: normal operation current < motor overload current < motor short-circuit current.

[0008] As a further solution of the utility model: the reference voltage REF1 for overload protection is less than the reference voltage REF2 for short circuit protection.

[0009] As a further solution of the utility model: the field effect tube Q1 is a switch that cuts off the negative pole of the power supply of the DC motor M1.

[0010] Compared with the prior art, the utility model determines the current working state of the DC motor M1 by detecting the working current of the DC motor M1, and distinguishes whether the DC motor M1 is normal, overloaded or short-circuited. After the overload protection circuit or the short-circuit protection circuit detects that the DC motor M1 is overloaded or short-circuited, the negative pole of the power supply of the DC motor M1 is cut off and the DC motor M1 enters the protection state, thereby protecting the DC motor M1 and avoiding the problem of the motor catching fire or burning out. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 The utility model discloses an overload and short-circuit protection circuit of a DC motor controller for an aerial work platform. DETAILED DESCRIPTION

[0012] The utility model will be further described below in conjunction with the accompanying drawings.

[0013] like Figure 1 As shown, the overload and protection circuit of the DC motor controller of the aerial work platform includes an overload protection circuit and a short-circuit protection circuit: the overload protection circuit includes an operational amplifier U1A, the negative input terminal 2 pin of the operational amplifier U1A is connected to the overload protection reference voltage REF1, the 8th pin of the operational amplifier U1A is connected to the positive 5V power supply, and the 1st pin is divided into two paths, one is connected to the positive electrode of the diode D1, and the other is connected to the positive electrode of the diode D3; the negative electrode of the diode D1 is connected to the base of the transistor Q2; the negative electrode of the diode D3 is connected to the positive input terminal 3 pin of the operational amplifier; the 3rd pin of the operational amplifier is also connected to the ground through the capacitor C1 and connected to the short-circuit protection circuit through the resistor R3;

[0014] The short-circuit protection circuit includes an operational amplifier U1B, wherein the negative input terminal 6 pin of the operational amplifier U1B is connected to the reference voltage REF2 of the short-circuit protection, and the positive input terminal 5 pin of the operational amplifier U1B is respectively connected to the cathode of the diode D4 and one end of the resistor R4; the anode of the diode D4 is connected to the 7 pin of the operational amplifier U1B and to the anode of the diode D2; the other end of the resistor R4 is respectively connected to one end of the resistor R3 and the emitter 2 pin of the transistor Q2; the cathode of the diode D2 is connected to the base 1 pin of the transistor Q2.

[0015] Furthermore, the emitter of the transistor Q2 is also grounded through the resistor R1, and the collector pin 3 of the transistor Q2 is divided into two paths, one is connected to the pin 4 of the field effect transistor Q1, and the other is connected to one end of the resistor R2; the pin 1 of the field effect transistor Q1 is grounded through the resistor R1, and the pin 5 of the field effect transistor Q1 is connected to one end of the DC motor M1; the other end of the DC motor M1 is respectively connected to the positive electrode of the power supply and the other end of the resistor R2.

[0016] Furthermore, the current relationship between the normal operation and overload and short-circuit operation of the DC motor M1 is: normal operation current < motor overload current < motor short-circuit current.

[0017] Further, the reference voltage REF1 for overload protection is less than the reference voltage REF2 for short circuit protection.

[0018] Furthermore, the field effect transistor Q1 is a switch that cuts off the negative pole of the power supply of the DC motor M1.

[0019] The working process of the utility model is as follows: when the voltage of the resistor R1 is greater than the reference voltage REF1 of the overload protection of the pin 2 detected by the filter delay of the operational amplifier U1A at the 3rd pin, the pin 1 outputs a high level to drive the triode Q2 to turn off the field effect tube Q1, so as to cut off the negative pole protection of the power supply of the DC motor M1; and the high level is fed back to the pin 3 of the operational amplifier U1A through the diode D3 for self-locking, so as to achieve overload protection and self-locking. When the voltage of the resistor R1 is greater than the reference voltage REF2 of the short-circuit protection of the pin 6 detected by the operational amplifier U1B at the 5th pin, the pin 7 outputs a high level to drive the triode Q2 to turn off the field effect tube Q1, so as to cut off the negative pole protection of the power supply of the DC motor M1; and the high level is fed back to the pin 5 of the operational amplifier U1B for self-locking, so as to achieve short-circuit protection and self-locking. Since the overload protection circuit includes the capacitor C1, filtering and delay will be performed, so when a short circuit occurs, the overload protection circuit will not be started, and the short-circuit protection circuit will react quickly and give priority to short-circuit protection.

Claims

1. Overload and short circuit protection circuit of DC motor controller for aerial work platform, including overload protection circuit and short circuit protection circuit, characterized in that: The overload protection circuit comprises an operational amplifier U1A, wherein the negative input terminal pin 2 of the operational amplifier U1A is connected to the reference voltage REF1 for overload protection, the pin 8 of the operational amplifier U1A is connected to the positive 5V power supply, the pin 1 is divided into two paths, one path is connected to the positive electrode of the diode D1, and the other path is connected to the positive electrode of the diode D3; the negative electrode of the diode D1 is connected to the base of the transistor Q2; the negative electrode of the diode D3 is connected to the positive input terminal pin 3 of the operational amplifier; the pin 3 of the operational amplifier is also connected to the ground through the capacitor C1 and connected to the short-circuit protection circuit through the resistor R3; The short-circuit protection circuit includes an operational amplifier U1B, wherein the negative input terminal 6 pin of the operational amplifier U1B is connected to the reference voltage REF2 for short-circuit protection, and the positive input terminal 5 pin of the operational amplifier U1B is respectively connected to the cathode of the diode D4 and one end of the resistor R4; the anode of the diode D4 is connected to the 7 pin of the operational amplifier U1B and to the anode of the diode D2; the other end of the resistor R4 is respectively connected to one end of the resistor R3 and the emitter 2 pin of the transistor Q2; the cathode of the diode D2 is connected to the base 1 pin of the transistor Q2.

2. The overload and short circuit protection circuit of the DC motor controller for aerial work platform according to claim 1 is characterized in that: The emitter of the transistor Q2 is also grounded through the resistor R1, and the collector pin 3 of the transistor Q2 is divided into two paths, one is connected to the pin 4 of the field effect transistor Q1, and the other is connected to one end of the resistor R2; the pin 1 of the field effect transistor Q1 is grounded through the resistor R1, and the pin 5 of the field effect transistor Q1 is connected to one end of the DC motor M1; the other end of the DC motor M1 is respectively connected to the positive electrode of the power supply and the other end of the resistor R2.

3. The overload and short circuit protection circuit of the DC motor controller for aerial work platform according to claim 2 is characterized in that: The current relationship between the normal operation and overload and short circuit operation of the DC motor M1 is: normal operation current < motor overload current < motor short circuit current.

4. The overload and short circuit protection circuit of the DC motor controller for aerial work platform according to claim 1 or 2, characterized in that: The overload protection reference voltage REF1 is less than the short circuit protection reference voltage REF2.

5. The overload and short circuit protection circuit of the DC motor controller for aerial work platform according to claim 2 is characterized in that: The field effect tube Q1 is a switch that cuts off the negative pole of the power supply of the DC motor M1.

Images