CN203979586U - A kind of multipath electrovalve flash control and flash current sampling circuit - Google Patents

Abstract

The utility model discloses a high-side control and high-side current sampling circuit of a multi-channel electromagnetic valve. The solenoid valve coil is connected to the output end of the high-side driver through a current sampling resistor, and the high-side driver is connected to a voltage source Vcc and a square wave is generated. It also includes a current sampling amplifier circuit, the two input terminals of the current sampling amplifier circuit are respectively connected to the two ends of the current sampling resistor, and the output terminal of the current sampling amplifier circuit is used to connect to the processor; the current sampling amplifier circuit includes a circuit connected to the current sampling A common-mode step-down circuit at both ends of the resistor, and a two-stage amplifier circuit connected to the output of the common-mode step-down circuit. The beneficial effect of the utility model is that the traditional low-side driver is changed into a high-side drive mode. The high-side switch controls the power supply. When the switch is turned off, there is no electricity in the circuit controlled by the switch, and there is no potential safety hazard in the event of a short circuit to the ground. .

Description

A multi-channel solenoid valve high-side control and high-side current sampling circuit

technical field

The utility model relates to the field of automobile electronic control, in particular to a high-side control and high-side current sampling circuit of a multi-channel electromagnetic valve.

Background technique

In recent years, automatic transmissions have been widely used in various vehicles, and their convenient, simple and safe operation methods are favored by drivers. For the transmission system, it is a key powertrain system. How to ensure the reliability and safety of the system operation deserves everyone's attention. In the gearbox controller system, solenoid valves are divided into two types: on-off solenoid valves and proportional regulating solenoid valves. The on-off solenoid valves pass a certain current or voltage to energize the internal coil of one of the battery valves, and then drive the internal needle valve. Or the ball valve is displaced, thereby blocking or opening the oil circuit, which is used to control the gear shift ratio adjustment. Existing solenoid valves mostly adopt the low-side driving method, and the driver is connected to the ground end of the solenoid valve coil, but this setting method is less safe, and there is a short circuit to the ground due to damage to the wiring harness, which may cause functional failure or safety hazards.

Invention content:

The technical problem to be solved by the utility model is to provide a multi-channel solenoid valve high-side control and high-side current sampling circuit. A drive switch is set on the high side of the solenoid valve coil, and the current sampling resistor is sampled through the current sampling amplification circuit.

In order to solve the above technical problems, the technical solution of the utility model is a multi-channel solenoid valve high-side control and high-side current sampling circuit, including a solenoid valve, one end of the solenoid valve coil is grounded, and the other end of the solenoid valve coil passes through a current sampling resistor Connected to the output terminal of the high-side driver, the high-side driver is connected to the voltage source Vcc and the square wave generator; it also includes a current sampling amplifier circuit, the two input terminals of the current sampling amplifier circuit are respectively connected to the two ends of the current sampling resistor, and the current sampling The output end of the amplifier circuit is used to connect to the processor; the current sampling amplifier circuit includes a common-mode step-down circuit connected to both ends of the current sampling resistor, and a two-stage amplifier circuit connected to the output end of the common-mode step-down circuit.

Preferably, several solenoid valves are included, and each solenoid valve is respectively connected to the output end of the high-side driver through a current sampling resistor, and the two ends of each current sampling resistor are correspondingly connected to a current sampling amplifier circuit.

Preferably, the two-stage amplifying circuit is recorded as a first-stage amplifying circuit and a second-stage amplifying circuit, the first-stage amplifying circuit includes a first operational amplifier U1, the non-inverting input terminal of the first operational amplifier U1 is grounded through a matching resistor R4, and the opposite A matching resistor R5 is connected between the phase input terminal and the output terminal; the second-stage amplifying circuit includes a second operational amplifier U2, and the non-inverting input terminal of the second operational amplifier U2 is connected to the output terminal of the first-stage amplifying circuit through a matching resistor R3. A matching resistor R6 is connected between the inverting input terminal and the output terminal, and the inverting input terminal of the second operational amplifier U2 is grounded through the matching resistor R8.

Preferably, the common-mode step-down circuit includes two drop-down resistors, one end of the first drop-down resistor R3 is connected between the current sampling resistor and the high-side driver, and the other end is connected to the non-inverting input end of the first operational amplifier U1, One end of the second drop resistor R4 is connected between the current sampling resistor and the solenoid valve, and the other end is connected to the inverting input end of the first operational amplifier U1.

Preferably, a freewheel protection circuit is also included, one end of the freewheel protection circuit is connected between the current sampling resistor and the high-side driver, and the other end is grounded.

Preferably, each current sampling resistor is correspondingly provided with a freewheeling protection circuit, and several freewheeling protection circuits are connected in parallel.

Preferably, the freewheeling protection circuit is a diode, and the positive end of the diode is grounded.

The beneficial effect of the utility model is that the traditional low-side driver is changed into a high-side drive mode. The high-side switch controls the power supply. When the switch is turned off, there is no electricity in the circuit controlled by the switch, and there is no potential safety hazard in the event of a short circuit to the ground. . It greatly reduces the risk of short circuit caused by the control circuit is still live after the traditional low-side switch is disconnected. At the same time, the high-side current sampling circuit is used to sample the voltage at both ends of the current sampling resistor, and the differential signal at both ends of the current sampling resistor is converted into a terminal-to-ground signal through a common-mode step-down circuit, and then the required differential signal is converted into a signal through a two-stage amplifier circuit. The mode voltage is amplified to the range required by the system to avoid the risk that the common mode voltage at the input terminal may exceed the normal working range of the op amp when only one stage of op amp is used, causing the circuit to lose its amplification function. The voltage at both ends of the current sampling resistor is output to the processor through the current sampling amplifier circuit, which can also realize the subsequent detection of various faults of the solenoid valve and the prevention of overload of the solenoid valve.

Description of drawings

Fig. 1 is the structural representation of the utility model embodiment,

FIG. 2 is a schematic structural diagram of a current sampling amplifier circuit according to an embodiment of the present invention.

In the picture:

1. Square wave generator, 2. High side driver, 3. Current sampling amplifier circuit, 4. Processor.

Detailed ways

Below in conjunction with accompanying drawing and embodiment the utility model is described further.

As shown in Figure 1, a multi-channel solenoid valve high-side control and high-side current sampling circuit includes two solenoid valves, namely solenoid valve L1 and solenoid valve L2, and one end of the coil of solenoid valve L1 and solenoid valve L2 is grounded. The other end of the solenoid valve L1 coil is connected to the output end of the high-side driver 2 through the current sampling resistor R1, the other end of the solenoid valve L2 coil is connected to the output end of the high-side driver 2 through the current sampling resistor R2, and the high-side driver 2 is connected to a voltage source. The input terminal is connected to the output terminal of the square wave generator 1; the two ends of the current sampling resistor R1 and the two ends of the current sampling resistor R2 are respectively connected to a current sampling amplifier circuit 3, and the output terminal of the current sampling amplifier circuit 3 is used to connect Processor4. The high-side driver 2 in this embodiment adopts the TLE6288 type of Infineon. The two current sampling resistors R1 and R2 are respectively provided with a freewheeling protection circuit, the two freewheeling protection circuits are connected in parallel, and the freewheeling protection circuit is a diode. Specifically, this embodiment includes two freewheeling protection circuit diodes D1 and D2, D1 The negative terminal of D2 is connected between the current sampling resistor R1 and the high-side driver 2, the positive terminal is grounded, the negative terminal of D2 is connected between the current sampling resistor R2 and the high-side driver 2, and the positive terminal is grounded.

Taking the current sampling amplifier circuit 3 of the current sampling resistor R1 as an example, as shown in FIG. 2 , it includes a common-mode step-down circuit connected to both ends of the current-sampling resistor R1 and a two-stage amplifier circuit connected to the output of the common-mode step-down circuit.

The two-stage amplifying circuit is denoted as the first-stage amplifying circuit and the second-stage amplifying circuit. The first-stage amplifying circuit includes a first operational amplifier U1. The non-inverting input terminal of the first operational amplifier U1 is grounded through a matching resistor R5, and the inverting input terminal and A matching resistor R6 is connected between the output terminals; the second-stage amplifying circuit includes a second operational amplifier U2, and the non-inverting input terminal of the second operational amplifier U2 is connected to the output terminal of the first-stage amplifying circuit through a matching resistor R7, and the inverting input terminal A matching resistor R9 is connected between the terminal and the output terminal, and the inverting input terminal of the second operational amplifier is grounded through the matching resistor R8.

The common-mode step-down circuit includes two drop-down resistors. One end of the first drop-down resistor R3 is connected between the current sampling resistor R1 and the high-side driver 2, and the other end is connected to the non-inverting input end of the first operational amplifier U1. One end of the drop resistor R4 is connected between the current sampling resistor R1 and the solenoid valve coil L1, and the other end is connected to the inverting input end of the first operational amplifier U1.

The resistance value of the step-down resistor in the common-mode step-down circuit and the resistance values of the two matching resistors R5 and R6 in the first-stage amplifier circuit should meet the following conditions:

(2Vin-Vrt)*R5/2*(R3+R5)<VIR,

(2Vin-Vrt)*R6/2*(R4+R6)<VIR,

Where Vin is the voltage value at the upper end of the current sampling resistor, Vrt is the voltage value at both ends of the current sampling resistor, and VIR is the maximum value of the common-mode voltage range of the first operational amplifier U1.

Through the setting of the resistance value above, the input common-mode voltage of the first-stage operational amplifier is reduced to within the application range of the operational amplifier, and at the same time, the differential signal at both ends of the current sampling resistor R1 is converted into a single-ended signal to ground, and the second-stage The op amp then amplifies the required differential-mode voltage to the range required by the system. The magnification of the second-stage amplifying circuit can be set according to system design requirements.

A PWM drive signal is generated by the square wave generator 1 to control the switch of the high side driver 2 to realize the control of the solenoid valve. In this embodiment, a common operational amplifier is used to build a current detection circuit. In the first-stage amplifying circuit, a resistor divider is used to reduce the high-side common-mode voltage by a certain percentage, so that it is within the input common-mode range of the current-sensing amplifier. Then, according to the system The design requires setting the magnification of the second-stage amplifying circuit.

Most of the current cars are negative ground, and there are a series of benefits to using high-side switches to supply power to the load. One of the significant effects is to reduce the open circuit caused by wire damage and improve the reliability of the system. If one end of the load is directly connected to the ground of the chassis, only one wire is needed to power the load, which also saves system cost.

It should be understood that those skilled in the art can make improvements or changes based on the above description, and all these improvements and changes should belong to the protection scope of the appended claims of the present utility model.

Claims (7)

1. multipath electrovalve flash control and flash current sampling circuit, comprise solenoid valve, described electromagnetic valve coil one end ground connection, it is characterized in that: the other end of described electromagnetic valve coil is connected in the output terminal of high side drivers (2) by a current sampling resistor, described high side drivers (2) connects voltage source Vcc and square-wave generator (1); Also comprise current sample amplification circuit (3), two input ends of described current sample amplification circuit (3) are connected to the two ends of described current sampling resistor, and the output terminal of described current sample amplification circuit (3) is used for connecting processor (4); Described current sample amplification circuit (3) comprises the common mode reduction voltage circuit that is connected to current sampling resistor two ends, and is connected to the two-stage amplification circuit of described common mode reduction voltage circuit output terminal.

2. a kind of multipath electrovalve flash according to claim 1 control and flash current sampling circuit, it is characterized in that: comprise several solenoid valves, described in each, solenoid valve is connected in respectively the output terminal of described high side drivers (2) by a current sampling resistor, and the two ends of each described current sampling resistor are connected respectively in a described current sample amplification circuit (3).

3. a kind of multipath electrovalve flash according to claim 1 control and flash current sampling circuit, it is characterized in that: described two-stage amplification circuit is designated as first order amplification circuit and second level amplification circuit, described first order amplification circuit comprises the first operational amplifier U1, the in-phase input end of described the first operational amplifier U1, by build-out resistor R4 ground connection, is connected with build-out resistor R5 between inverting input and output terminal; Described second level amplification circuit comprises the second operational amplifier U2, the in-phase input end of described the second operational amplifier U2 is connected in the output terminal of described first order amplification circuit by build-out resistor R3, between inverting input and output terminal, be connected with build-out resistor R6, the inverting input of described the second operational amplifier U2 is by build-out resistor R8 ground connection.

4. a kind of multipath electrovalve flash according to claim 1 control and flash current sampling circuit, it is characterized in that: described common mode reduction voltage circuit comprises two quenching resistors, one end of the first quenching resistor R3 is connected between described current sampling resistor and high side drivers (2), the other end is connected to the in-phase input end of described the first operational amplifier U1, one end of the second quenching resistor R4 is connected between described current sampling resistor and solenoid valve, and the other end is connected to the inverting input of described the first operational amplifier U1.

5. a kind of multipath electrovalve flash according to claim 1 control and flash current sampling circuit; it is characterized in that: also comprise afterflow protective circuit; described afterflow protective circuit one end is connected between described current sampling resistor and high side drivers (2), the other end ground connection.

6. a kind of multipath electrovalve flash according to claim 5 control and flash current sampling circuit, is characterized in that: each described current sampling resistor correspondence arranges an afterflow protective circuit, the parallel connection of several described afterflow protective circuit.

7. according to a kind of multipath electrovalve flash control described in claim 5 or 6 and flash current sampling circuit, it is characterized in that: described afterflow protective circuit is diode the positive terminal ground connection of described diode.