Control circuit using H-bridge chip to drive disengagement mechanism

Abstract

The invention discloses a control circuit using an H-bridge chip to drive a disengagement mechanism, comprising an MCU chip and an H-bridge chip, the H-bridge chip is connected between the MCU chip and the disengagement mechanism, the H-bridge chip comprises a switch tube Q1, a switch tube Q2, a switch tube Q3 and a switch tube Q4, and the switch tube Q1, the switch tube Q2, the switch tube Q3 and the switch tube Q4 are connected with the H-bridge chip. The source electrode of the switch tube Q1 is electrically connected with the drain electrode of the switch tube Q3, and the source electrode of the switch tube Q2 is electrically connected with the drain electrode of the switch tube Q4. According to the control circuit using the H-bridge chip to drive the disengagement mechanism, compared with the first scheme, the H-bridge chip is usually integrated with protection of overcurrent, overheating, undervoltage locking and the like, and the requirement for an external protection circuit is reduced; compared with a second scheme, a half-bridge circuit in an H bridge is used, a half-bridge MOS (Metal Oxide Semiconductor) has the characteristic of low gate-level charge Qg, high-frequency switching control of 100kHz at most can be supported, and the switching power consumption is low.

Description

Technical Field

[0001] The invention belongs to the technical field of disengagement mechanism control, and in particular relates to a control circuit that uses an H-bridge chip to drive a disengagement mechanism. Background Art

[0002] The disengagement mechanism is used to open and close between the motor and the wheels of new energy hybrid vehicles. When the motor is needed to work, the disengagement mechanism is controlled to enter the closed state and connect to the wheel. When the motor is not needed to work, the disengagement mechanism is controlled to enter the disengaged state and disconnect from the wheel.

[0003] Currently, the actuator of the disengagement mechanism is an electromagnet, and its control module is usually installed in the motor controller. The PWM wave (proportional integral control) emitted by the microcontroller is used to adjust the current on the electromagnet to keep it in a constant current state, ensuring constant magnetic force and continuous normal operation.

[0004] 1. Solution 1 is low-side MOS control, such as Figure 1 As shown, a disconnect mechanism exists between points A and B. The MCU samples the current through an op amp and sampling resistor, then uses proportional-integral control to output a PWM wave to control the on and off of the MOS, achieving constant current control. The control circuit lacks a fault diagnosis circuit. If points A or B short to ground or power, fault protection and fault status recording are unavailable, requiring external protection circuitry for the entire drive circuit.

[0005] 2. Option 2 is a high-side drive circuit, such as Figure 2 As shown, the MOS integrated in the high-side driver chip U1 is used for control. However, the MOS integrated in the current high-side driver chip has a large Qg parameter and is generally used for normally open and normally closed control of relays. If used in PWM control constant current conditions such as the tripping mechanism, a switching frequency of more than 1kHz is required, which will lead to large switching losses and cause the high-side driver chip to enter thermal protection and fail to work normally.

[0006] Therefore, further improvements are made to the above problems. Summary of the Invention

[0007] The main purpose of the present invention is to provide a control circuit that uses an H-bridge chip to drive a disengagement mechanism. The present invention uses an H-bridge chip. Compared with solution one, the H-bridge chip often integrates overcurrent, overheating, undervoltage lockout (UVLO) and other protections, reducing the need for external protection circuits, which is conducive to software monitoring of faults and implementing protection. Compared with solution two, the half-bridge circuit in the H-bridge is used. Its half-bridge MOS has the characteristics of low gate-level charge Qg, can support high-frequency switching control of up to 100kHz, and has low switching power consumption; at the same time, it can continue the current through the lower tube Q3 of the half-bridge, which is less power-consuming than the external diode of the high-side switch.

[0008] To achieve the above objectives, the present invention provides a control circuit using an H-bridge chip to drive a disengagement mechanism, comprising an MCU chip and an H-bridge chip (U1), wherein the H-bridge chip is connected between the MCU chip and the disengagement mechanism, and the H-bridge chip comprises a switch tube Q1, a switch tube Q2, a switch tube Q3, and a switch tube Q4, wherein:

[0009] The source of the switch tube Q1 is electrically connected to the drain of the switch tube Q3, and the source of the switch tube Q2 is electrically connected to the drain of the switch tube Q4. The drain of the switch tube Q1 and the drain of the switch tube Q2 are electrically connected and connected to the supply voltage Vin. The source of the switch tube Q3 and the source of the switch tube Q4 are electrically connected and grounded. The source of the switch tube Q1 is connected to the output terminal OUT1, and the source of the switch tube Q2 is connected to the output terminal OUT2. The output terminal OUT1 is grounded in sequence through a disconnection mechanism and a sampling resistor R1, and the output terminal OUT1 is directly grounded.

[0010] The two ends of the sampling resistor R1 are electrically connected to the positive input terminal and the negative input terminal of the operational amplifier U2 respectively, and the output terminal of the operational amplifier U2 is electrically connected to the MCU chip;

[0011] (During the startup phase of the disengagement mechanism, it is necessary to overcome the spring force and friction force, and a larger starting current is required to generate a magnetic force. When the disengagement unit is in place, a smaller current is required to maintain it in position. Therefore, the main control MCU will collect real-time current, control the switching duty cycle of the MOSFET to perform closed-loop PID control, so that the current of the disengagement mechanism reaches the starting current and holding current required by the manufacturer.) During the working phase of the disengagement mechanism, the MCU chip samples the current of the disengagement mechanism through the operational amplifier U2 and the sampling resistor R1, and then adjusts the output according to the real-time current demand through SPI communication with the H-bridge chip. Finally, the disengagement mechanism is put into a constant current state through closed-loop control (to ensure constant magnetic force and continuous normal operation). The closed-loop control is specifically implemented as follows:

[0012] Phase 1: The switch tube Q1 is turned on, the switch tube Q3 is turned off, and the current flows through the switch tube Q1 and then to the ground through the disconnect mechanism;

[0013] Phase 2: Switches Q1 and Q3 are turned off at the same time, and the body diode of switch Q3 achieves freewheeling.

[0014] Phase 3: The switch tube Q3 is turned on to achieve freewheeling and reduce power consumption;

[0015] Phase 4: Switches Q3 and Q1 are turned off at the same time, and the body diode of switch Q3 achieves freewheeling.

[0016] Phase 5: The switch tube Q1 is turned on again and the operation is repeated to realize the driving control.

[0017] As a further preferred technical solution of the above technical solution, the negative input terminal and the output terminal of the operational amplifier U2 are electrically connected.

[0018] As a further preferred technical solution of the above technical solution, the H-bridge chip integrates protection functions including overcurrent, overheating, and undervoltage lockout (UVLO).

[0019] As a further preferred technical solution of the above technical solution, the enable terminal (EN) of the H-bridge chip is electrically connected to the MCU chip.

[0020] As a further preferred technical solution of the above technical solution, the fault indication terminal (FLT) of the H-bridge chip is electrically connected to the MCU chip.

[0021] The beneficial effects of the present invention are:

[0022] 1. The drive protection function can be realized without external circuit, effectively saving PCB layout space.

[0023] 2. Without using traditional diode freewheeling, the heating of the entire circuit is controlled and the heat dissipation design is convenient.

[0024] 3. The built-in switch tube has a low gate charge Qg, which is suitable for high-frequency constant current control greater than 1kHz. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 This is a circuit diagram of an existing low-side control disengagement mechanism.

[0026] Figure 2 This is a circuit diagram of an existing high-side control disengagement mechanism.

[0027] Figure 3 This is a control circuit diagram of the present invention using an H-bridge chip to drive a disengagement mechanism. DETAILED DESCRIPTION

[0028] The following description is intended to disclose the present invention so that those skilled in the art can implement the present invention. The preferred embodiments described below are for illustrative purposes only, and those skilled in the art will readily appreciate other obvious variations. The basic principles of the present invention defined in the following description may be applied to other embodiments, variations, improvements, equivalents, and other technical solutions that do not depart from the spirit and scope of the present invention.

[0029] In the preferred embodiment of the present invention, those skilled in the art should note that the disengagement mechanism and the like involved in the present invention may be regarded as prior art.

[0030] Preferred embodiment.

[0031] like Figure 3As shown, the present invention discloses a control circuit using an H-bridge chip to drive a disengagement mechanism, comprising an MCU chip and an H-bridge chip (U1), wherein the H-bridge chip is connected between the MCU chip and the disengagement mechanism, and the H-bridge chip comprises a switch tube Q1, a switch tube Q2, a switch tube Q3 and a switch tube Q4, wherein:

[0032] The source of the switch tube Q1 is electrically connected to the drain of the switch tube Q3, and the source of the switch tube Q2 is electrically connected to the drain of the switch tube Q4. The drain of the switch tube Q1 and the drain of the switch tube Q2 are electrically connected and connected to the supply voltage Vin. The source of the switch tube Q3 and the source of the switch tube Q4 are electrically connected and grounded. The source of the switch tube Q1 is connected to the output terminal OUT1, and the source of the switch tube Q2 is connected to the output terminal OUT2. The output terminal OUT1 is grounded in sequence through a disconnection mechanism and a sampling resistor R1, and the output terminal OUT1 is directly grounded.

[0033] The two ends of the sampling resistor R1 are electrically connected to the positive input terminal and the negative input terminal of the operational amplifier U2 respectively, and the output terminal of the operational amplifier U2 is electrically connected to the MCU chip;

[0034] (During the startup phase of the disengagement mechanism, it is necessary to overcome the spring force and friction force, and a larger starting current is required to generate a magnetic force. When the disengagement unit is in place, a smaller current is required to maintain it in position. Therefore, the main control MCU will collect real-time current, control the switching duty cycle of the MOSFET to perform closed-loop PID control, so that the current of the disengagement mechanism reaches the starting current and holding current required by the manufacturer.) During the working phase of the disengagement mechanism, the MCU chip samples the current of the disengagement mechanism through the operational amplifier U2 and the sampling resistor R1, and then adjusts the output according to the real-time current demand through SPI communication with the H-bridge chip. Finally, the disengagement mechanism is put into a constant current state through closed-loop control (to ensure constant magnetic force and continuous normal operation). The closed-loop control is specifically implemented as follows:

[0035] Phase 1: The switch tube Q1 is turned on, the switch tube Q3 is turned off, and the current flows through the switch tube Q1 and then to the ground through the disconnect mechanism;

[0036] Phase 2: Switches Q1 and Q3 are turned off at the same time, and the body diode of switch Q3 achieves freewheeling.

[0037] Phase 3: The switch tube Q3 is turned on to achieve freewheeling and reduce power consumption;

[0038] Phase 4: Switches Q3 and Q1 are turned off at the same time, and the body diode of switch Q3 achieves freewheeling.

[0039] Phase 5: The switch tube Q1 is turned on again and the operation is repeated to realize the drive control (during the operation of the disconnect mechanism, the closed-loop control phases 1 to 5 will continue to cycle. During this process, the MCU chip compares the real-time current sampling feedback with the target value, continuously adjusts the duty cycle of the output signal, and finally makes the disconnect mechanism work normally).

[0040] Specifically, the negative input terminal and the output terminal of the operational amplifier U2 are electrically connected.

[0041] More specifically, the H-bridge chip integrates protection functions including overcurrent, overheating, and undervoltage lockout (UVLO).

[0042] Furthermore, the enable terminal (EN) of the H-bridge chip is electrically connected to the MCU chip.

[0043] Furthermore, the fault indication terminal (FLT) of the H-bridge chip is electrically connected to the MCU chip.

[0044] In this embodiment, the diode freewheeling time is extremely short during operation, the MOS conduction power consumption is low, and the heat generated by freewheeling is much lower than in Schemes 1 and 2. During the control phase, the gate charge of the MOS built into the H-bridge is much lower than that of the high-side driver chip, resulting in lower open-drain losses. In summary, this solution consumes less power and generates less heat.

[0045] H-bridge chips often integrate protections such as overcurrent, overheating, and undervoltage lockout (UVLO). Once an abnormal condition such as overtemperature or overcurrent occurs, the chip will actively shut down the output and interact with the MCU to report the fault. This can achieve protection and fault recording, comprehensive monitoring and protection, and reduce the need for external protection circuits.

[0046] The present invention does not require the use of any external circuits, relies on its own hardware fault protection logic processing, and can communicate with the MCU via SPI, which can solve the protection difficulty of the low-side drive solution; at the same time, it solves the problem of large gate charge Qg in the high-side drive solution and severe heat generation when the frequency is controlled above 1kHz. There is no need to rely on diode freewheeling, and freewheeling is achieved in combination with the lower bridge, resulting in low heat generation and no over-temperature protection during normal operation.

[0047] It is worth mentioning that the technical features such as the disengagement mechanism involved in the patent application of this invention should be regarded as prior art. The specific structure, working principle and possible control method and spatial layout method of these technical features can be selected by conventional means in the field and should not be regarded as the inventive point of the patent of this invention. The patent of this invention will not be further elaborated.

[0048] For those skilled in the art, it is still possible to modify the technical solutions described in the aforementioned embodiments, or to make equivalent replacements for some of the technical features therein. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A control circuit using an H-bridge chip to drive a disengagement mechanism, characterized in that: It includes an MCU chip and an H-bridge chip, wherein the H-bridge chip is connected between the MCU chip and the disconnection mechanism, and the H-bridge chip includes a switch tube Q1, a switch tube Q2, a switch tube Q3 and a switch tube Q4, wherein: The source of the switch tube Q1 is electrically connected to the drain of the switch tube Q3, and the source of the switch tube Q2 is electrically connected to the drain of the switch tube Q4. The drain of the switch tube Q1 and the drain of the switch tube Q2 are electrically connected and connected to the supply voltage Vin. The source of the switch tube Q3 and the source of the switch tube Q4 are electrically connected and grounded. The source of the switch tube Q1 is connected to the output terminal OUT1, and the source of the switch tube Q2 is connected to the output terminal OUT2. The output terminal OUT1 is grounded in sequence through a disconnection mechanism and a sampling resistor R1, and the output terminal OUT1 is directly grounded. The two ends of the sampling resistor R1 are electrically connected to the positive input terminal and the negative input terminal of the operational amplifier U2 respectively, and the output terminal of the operational amplifier U2 is electrically connected to the MCU chip; During the working phase of the disconnect mechanism, the MCU chip samples the current of the disconnect mechanism through the operational amplifier U2 and the sampling resistor R1, and then adjusts the output according to the real-time current demand through SPI communication with the H-bridge chip. Finally, the disconnect mechanism is put into a constant current state through closed-loop control. The closed-loop control is specifically implemented as follows: Phase 1: The switch tube Q1 is turned on, the switch tube Q3 is turned off, and the current flows through the switch tube Q1 and then to the ground through the disconnect mechanism; Phase 2: Switches Q1 and Q3 are turned off at the same time, and the body diode of switch Q3 achieves freewheeling. Phase 3: The switch tube Q3 is turned on to achieve freewheeling and reduce power consumption; Phase 4: Switches Q3 and Q1 are turned off at the same time, and the body diode of switch Q3 achieves freewheeling. Phase 5: The switch tube Q1 is turned on again and the operation is repeated to realize the driving control.

2. A control circuit using an H-bridge chip to drive a disengagement mechanism according to claim 1, characterized in that: The negative input terminal and the output terminal of the operational amplifier U2 are electrically connected.

3. The control circuit using an H-bridge chip to drive a disengagement mechanism according to claim 2, characterized in that: The H-bridge chip integrates protection functions including overcurrent, overheating, and undervoltage lockout.

4. A control circuit using an H-bridge chip to drive a disengagement mechanism according to claim 3, characterized in that: The enable terminal of the H-bridge chip is electrically connected to the MCU chip.

5. The control circuit for driving a disengagement mechanism using an H-bridge chip according to claim 4, characterized in that: The fault indication terminal of the H-bridge chip is electrically connected to the MCU chip.

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