CN209462022U - A kind of vehicle-mounted DC/DC converter prevents output reverse-connection damage circuit - Google Patents

Abstract

The utility model relates to the protection circuits that vehicle-mounted DC/DC converter field more particularly to a kind of vehicle-mounted DC/DC converter prevent output with the positive and negative reversal connection of battery and damage.The circuit output voltage anode is connect by first diode with low tension battery anode, the drain electrode that output voltage cathode meets the source electrode low-voltage, high-current MOSFET of low-voltage, high-current MOSFET is connect with low tension battery cathode, and driving circuit is arranged on the low-voltage, high-current MOSFET.The utility model utilizes the low conduction impedance between the unilateal conduction characteristic of low-voltage, high-current MOSFET diode-built-in, low-voltage, high-current MOSFET hourglass source electrode, the advantages such as low-voltage, high-current MOSFET is small in size, price is low, and cooperate corresponding control circuit, replace between vehicle-mounted DC/DC converter and low tension battery for it is anti-reverse damage and concatenated fuse or DC relay, efficiently solve the problems, such as converter output it is positive and negative with low tension battery it is positive and negative it is reversed after damage converter, and circuit is cheap, realize simple, high reliablity, to account for plate space small.

Description

A kind of vehicle-mounted DC/DC converter prevents output reverse-connection damage circuit

Technical field

The utility model relates to vehicle-mounted DC/DC converter fields more particularly to a kind of vehicle-mounted DC/DC converter to prevent from exporting The positive and negative protection circuit with the positive and negative reversal connection of low tension battery and damage.

Background technique

Vehicle-mounted DC/DC converter applications are in pure electric automobile or oil-electric vehicle, by vehicle power battery high pressure Voltage transformation is low voltage, is charged for low tension battery, and is the power supply of the low voltage equipments such as car light, rain brush, loudspeaker.

In vehicle assembling process, occasionally there is generation worker that DC/DC converter is exported the positive and negative and positive and negative company of low tension battery Wrong misses, and so as to cause the accident of converter damage, even converter output circuit detonation can be caused (in reality when accident is serious In, a lot of identical accidents were had occurred and that), therefore to require vehicle-mounted DC/DC converter to need to have output positive and negative for vehicle factor The function that will not be damaged after reversed with low tension battery.

In order to avoid DC/DC export it is positive and negative with battery it is positive and negative it is reversed after the accident that is damaged, in practical applications, generally Using by the way of output circuit serial fuse or DC relay, specific implementation circuit is as depicted in figs. 1 and 2.

In Fig. 1, DC/DC converter output circuit prevents from exporting by serial fuse positive and negative positive and negative with low tension battery A possibility that being damaged after reversed.

When normal work, converter anode connect conducting with low tension battery anode by fuse；Once converter is defeated Positive and negative positive and negative reversed with low tension battery out, then rectifier diode and fuse are short-circuit by low tension battery inside converter, this When short circuit current it is very big, fuse can be blown the short time, circuit disconnects, and can play the mesh for avoiding converter from further damaging 's.

In Fig. 2, when correctly connecting with low tension battery, DC relay is connected the output of DC/DC converter, and converter is to low Pressure battery charges normal；After the output of DC/DC converter is positive and negative positive and negative reversed with low tension battery, DC relay is not controlled Signal processed, is not turned on, and avoidable converter is damaged.

1, there is following drawback using fuse scheme:

1), fuse is installed on inside vehicle-mounted DC/DC converter, once damage, is difficult to replace at the scene, does not have operation Feasibility；

2), fuse, according to the larger surge current of design specification and physical presence, can generally be stayed when carrying out type selecting Have larger allowance, still, larger allowance may result in converter and low tension battery it is positive and negative it is reversed after, fuse is fusing Before, more device failures or even on fire are already led to inside converter, bigger loss is caused；

3), heavy DC fuse is expensive, difficult type selecting；

3), heavy DC fuse bulky is difficult inside layout to DC/DC converter.

2, using DC relay the shortcomings that is as follows:

1), expensive, it may be necessary to which that Shuo Baiyuan, it is very big that cost accounts for entire converter specific gravity；

2), volume is too big, is difficult inside layout to DC/DC converter；

3), the risk of contact adhesion easily occurs for high-current relay, is easily damaged, and reduces vehicle-mounted DC/DC transformation instead Device reliability；

4) electric current needed for, heavy DC relay control coil is closed is larger, increases DC/DC converter power consumption；

5), shock resistance is poor, and vehicle-mounted product needs good shock resistance, and relay is mostly mechanical relay Device, shock resistance is excessively poor, is not suitable with vehicle-mounted use environment；If selecting solid-state relay, arriving for shock resistance is improved, But price is costly.

Summary of the invention

In order to solve the above-mentioned technical problem, the utility model unidirectionally leading using low-voltage, high-current MOSFET diode-built-in The advantages that low conduction impedance, low-voltage, high-current MOSFET itself between electrical characteristics, hourglass source electrode is small in size, cheap, and match Corresponding control circuit is closed, replaces concatenated fuse or DC relay between DC/DC converter and low tension battery, effectively Ground solve the problems, such as converter output it is positive and negative with low tension battery it is positive and negative it is reversed damage afterwards, and cheap, high reliablity, Account for that plate space is small, is easily achieved.

The technical solution that the utility model is taken to achieve the above object are as follows:

A kind of vehicle-mounted DC/DC converter prevents output reverse-connection damage circuit, which includes output voltage anode and output Voltage cathode, the output voltage anode are connected by first diode with low tension battery anode, output voltage cathode The source electrode of low-voltage, high-current MOSFET is connected, the drain electrode of low-voltage, high-current MOSFET is connected with low tension battery cathode, described Low-voltage, high-current MOSFET on driving circuit is set.

As a further improvement, the driving circuit includes second resistance, the 4th resistance, the 7th resistance, the three or two pole Pipe, relay coil control MOSFET and single-pole single-throw(SPST relay, the grid and hilted broadsword list of the low-voltage, high-current MOSFET One end connection of relay power coil is thrown, relay coil controls MOSFET drain electrode and single-pole single-throw(SPST relay control coil One end connection, relay coil control MOSFET source are connected with low tension battery cathode, and relay coil controls MOSFET Grid is connect with the output of two comparators.

As a further improvement, the unidirectional sample circuit of voltage is arranged on the low tension battery, DC/DC converter is avoided After exporting the positive and negative and positive and negative reversal connection of low tension battery, negative pressure voltage is sent to comparator, and then damage comparison device；The low pressure The unidirectional sample circuit of battery voltage includes concatenated 3rd resistor, the 6th resistance and the 6th diode, the 6th resistance and the 6th Diode is connected with 3rd resistor carries out after unidirectionally dividing sampling low tension battery, and sampled voltage is being sent to a comparator just To input terminal, after the 8th resistance and the 9th resistance carry out partial pressure sampling to DC/DC output voltage, sampled voltage is sent to another ratio Compared with the positive input of device, the reverse input end of two comparators connects reference voltage, and the 7th diode is as two comparators Unidirectional ground connection diode, after avoiding the output of DC/DC converter positive and negative with the positive and negative reversal connection of low tension battery, voltage, which is applied to, to be compared Device ground wire.

With the output of other tradition DC/DC converters prevent low tension battery to be reversely connected and compared with damaging the mode of converter, this Utility model has the advantage that

1, easy type selecting has a large amount of low-voltage, high-current MOSFET in the market, easily chooses, and supplies and stablize；

2, price is low, and low-voltage, high-current MOSFET is largely popularized, and cost is very low；

3, control circuit is realized simple；

4, high reliablity, low-voltage, high-current MOSFET always work on state, in addition to conduction loss, do not switch damage Consumption, high reliablity；

5, low-voltage, high-current MOSFET is small in size, will not occupy DC/DC converter more space.

Detailed description of the invention

Fig. 1 is that existing use serial fuse prevents the output of DC/DC converter positive and negative positive and negative reversed with low tension battery After damage schematic diagram；

Fig. 2 is that existing use DC relay prevents the output of DC/DC converter positive and negative positive and negative reversed with low tension battery After damage schematic diagram；

Fig. 3 is utility model diagram.

Specific embodiment

It elaborates with reference to the accompanying drawing to the specific embodiment of the utility model.

As shown in figure 3, a kind of vehicle-mounted DC/DC converter prevents output reverse-connection damage circuit, which includes output voltage Anode+VOUT and output voltage cathode GND, the output voltage anode+VOUT pass through first diode D1 and low pressure electric power storage The connection of pond BATTERY anode, the source electrode of output voltage cathode GND connection low-voltage, high-current MOSFET Q2, low-voltage, high-current The drain electrode of MOSFET Q2 is connect with the cathode of low tension battery BATTERY, is arranged on the low-voltage, high-current MOSFETQ2 and is driven Dynamic circuit.The driving circuit includes second resistance R2, the 4th resistance R4, the 7th resistance R7, third diode D3, the two or two Pole pipe D2, relay coil control MOSFET Q1 and single-pole single-throw(SPST relay JK1, the low-voltage, high-current MOSFET Q2's Grid is connect with one end of single-pole single-throw(SPST relay JK1 power coil, and relay coil controls MOSFET Q1 drain electrode and hilted broadsword list One end connection of relay JK1 control coil is thrown, relay coil controls MOSFET Q1 source electrode and low tension battery BATTERY Cathode connection, relay coil control MOSFET Q1 grid are connect with the output of two comparators U2A, U2B.

The unidirectional sample circuit of voltage, the low tension battery BATTERY electricity are set on the low tension battery BATTERY Pressing unidirectional sample circuit includes concatenated 3rd resistor R3, the 6th resistance R6 and the 6th diode D6, the 6th resistance R6 and the 6th After diode D6 carries out unidirectional partial pressure sampling of connecting to low tension battery with 3rd resistor R3, sampled voltage is sent to comparator U2A Positive input, after the 8th resistance R5 and the 9th resistance R1 carry out partial pressure sampling to DC/DC output voltage, sampled voltage is sent to The positive input of comparator U2B, reference voltage are connected respectively to the reverse input end of comparator U2A and U2B, the 7th diode Unidirectional ground connection diode of the D7 as comparator U2A and U2B.

When converter output is normal and it is correct with the positive and negative connection of low tension battery after, two comparator sampling ends are (positive Input terminal) it is higher than reference edge (reverse input end), comparator exports high level, and relay coil controls MOSFET Q1 conducting, after The conducting of electrical equipment control coil, relay power coil are attracted, and low-voltage, high-current MOSFET Q2 grid obtains driving voltage and leads Logical, converter starts to charge to low tension battery.

If converter does not export, comparator U2B positive input no-voltage input, comparator U2B output is low Level connect correctness with low tension battery, and relay coil control MOSFET Q1 is not turned on, single-pole single-throw(SPST relay Device JK1 is not attracted, and low-voltage, high-current MOSFET Q2 grid is not turned on without driving voltage；If converter output it is positive and negative with it is low The positive and negative connection error of battery is pressed, because of the presence of low tension battery unidirectional voltage sample circuit, then comparator U2A forward direction inputs No voltage input is held, relay coil control MOSFET Q1 source electrode connects high level, and grid does not have forward bias voltage, do not lead Logical, single-pole single-throw(SPST relay JK1 is not attracted, then low-voltage, high-current MOSFET Q2 is not turned on, converter output and low tension battery Circuit is not constituted, a possibility that damaging converter after being reversely connected is avoided.

Claims (3)

1. a kind of vehicle-mounted DC/DC converter prevent output reverse-connection damage circuit, it is characterised in that: the circuit include output voltage just Pole and output voltage cathode, the output voltage anode are connected by first diode with the anode of battery, output electricity Pressure cathode is connected by the drain electrode of low-voltage, high-current field-effect tube with battery terminal negative, the low-voltage, high-current field-effect tube Upper setting driving circuit.

2. a kind of vehicle-mounted DC/DC converter according to claim 1 prevents output reverse-connection damage circuit, it is characterised in that: The driving circuit includes second resistance, the 4th resistance, the 7th resistance, third diode, relay coil control field-effect Pipe and single-pole single-throw(SPST relay, the grid of the low-voltage, high-current field-effect tube are connect with one end of single-pole single-throw(SPST relay, Relay coil control FET drain is connect with the other end of single-pole single-throw(SPST relay, and relay coil controls field-effect tube Source electrode is connected with battery terminal negative, and relay coil control fet gate is connect with the output of two comparators.

3. a kind of vehicle-mounted DC/DC converter according to claim 2 prevents output reverse-connection damage circuit, it is characterised in that: On the battery be arranged the single-phase sample circuit of voltage, the single-phase sample circuit of the voltage include concatenated 3rd resistor, The anode of 6th resistance and the 6th diode, one of comparator of two comparators passes through the 6th resistance and the 6th diode It is connected with the cathode of battery, the cathode of one of comparator is connected by the 7th diode with the cathode of battery.