An H-bridge motor braking circuit

Abstract

The present invention discloses an H-bridge motor braking circuit, comprising a controller, a motor, an H-bridge driving circuit and an adjustable voltage unit, wherein the H-bridge driving circuit comprises a first switch unit, a second switch unit, a third switch unit and a fourth switch unit which are electrically connected to the controller respectively, wherein the first switch unit and the second switch unit are electrically connected to the positive pole of the motor respectively, and the third switch unit and the fourth switch unit are electrically connected to the negative pole of the motor respectively, and at least one adjustable voltage unit is arranged between the controller and the H-bridge driving circuit. The gate driving voltage of at least one switch unit is adjusted by the adjustable voltage unit, and when the motor operates normally, the switch tube of the switch unit operates in a saturation region; when the motor is braked, the gate driving voltage of at least one switch unit is reduced, so that the switch tube of the switch unit operates in a linear amplification region, so as to increase the resistance of the switch tube, consume the current in the motor power generation state, and reduce the generated reverse electromotive force.

Description

Technical Field

[0001] The invention relates to the technical field of motor braking, and in particular to an H-bridge motor braking circuit. Background Art

[0002] The motor generally uses an H-bridge drive circuit to achieve forward and reverse rotation and speed control. When braking a high-speed rotating motor, the voltage is often adjusted by adjusting PWM to reduce the duty cycle of the H-bridge drive circuit, so that the motor can be slowly stopped in a controllable manner. However, during braking or deceleration, the motor may generate reverse electromotive force and become a generator after turning off or reducing PWM. When the current is transmitted to the bus through the freewheeling diode of the switch tube, the bus voltage will increase, causing high voltage stress on the H-bridge and the previous switching power supply, which may damage the circuit and affect the operation of the motor. Summary of the invention

[0003] In order to solve the above-mentioned technical defects, the technical solution adopted by the present invention is to provide an H-bridge motor braking circuit, including a controller, a motor, an H-bridge drive circuit and an adjustable voltage unit, the H-bridge drive circuit includes a first switch unit, a second switch unit, a third switch unit and a fourth switch unit respectively electrically connected to the controller, the first switch unit and the second switch unit are respectively electrically connected to the positive pole of the motor, the third switch unit and the fourth switch unit are respectively electrically connected to the negative pole of the motor, and at least one adjustable voltage unit is provided between the controller and the H-bridge drive circuit, and the adjustable voltage unit is used to adjust the gate drive voltage of at least one switch unit.

[0004] Furthermore, the adjustable voltage unit includes an operational amplifier, a power supply terminal of the operational amplifier is electrically connected to a first port of the controller, a non-inverting input terminal of the operational amplifier is electrically connected to a second port of the controller, a reverse input terminal of the operational amplifier is grounded, the operational amplifier is configured in a non-inverting amplification mode, and an output terminal of the operational amplifier is electrically connected to a gate of one of the switch units.

[0005] Furthermore, the adjustable voltage unit includes an emitter follower, the emitter follower includes a transistor, the base of the transistor is electrically connected to the second port of the controller, the collector of the transistor is electrically connected to the first port of the controller, and the emitter of the transistor is electrically connected to the gate of one of the switch units.

[0006] Furthermore, a first resistor is connected in series between the inverting input terminal and the output terminal of the operational amplifier.

[0007] Furthermore, the inverting input terminal of the operational amplifier is grounded through a second resistor.

[0008] Furthermore, the first port is a PWM output port.

[0009] Furthermore, the second port is a DAC output port.

[0010] Furthermore, the voltage range of the second port of the controller is 0-3.3V.

[0011] Furthermore, the first switch unit and the third switch unit are electrically connected to a DC voltage Vbus respectively.

[0012] Furthermore, the second switch unit and the fourth switch unit are both grounded via a third resistor.

[0013] Compared with the prior art, the beneficial effects of the technical solution of the present invention are as follows:

[0014] 1. An H-bridge motor braking circuit provided by the present invention adjusts the gate drive voltage of at least one switch unit through an adjustable voltage unit. When the motor operates normally, the switch tube of the switch unit operates in a saturation region. When the motor is braked, the gate drive voltage of at least one switch unit is reduced so that the switch tube of the switch unit operates in a linear amplification region to increase the resistance of the switch tube, consume the current in the motor generating state, and reduce the generated reverse electromotive force.

[0015] 2. The use of adjustable gate drive voltage expands the applicable types of switch tubes. By setting different drive voltages, the braking speed can be adjusted to achieve controllable absorption of reverse current. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0017] Figure 1 It is a braking principle diagram of an H-bridge motor braking circuit provided by an embodiment of the present invention;

[0018] Figure 2 1 is a circuit diagram of Embodiment 1 of an H-bridge motor braking circuit provided by an embodiment of the present invention;

[0019] Figure 3 is a circuit diagram of Embodiment 2 of an H-bridge motor braking circuit provided by an embodiment of the present invention;

[0020] Figure 4 is a circuit diagram of Embodiment 3 of an H-bridge motor braking circuit provided by an embodiment of the present invention;

[0021] Figure 5 4 is a circuit diagram of an H-bridge motor braking circuit provided by an embodiment of the present invention;

[0022] Figure 6 is a circuit diagram of Example 5 of an H-bridge motor braking circuit provided by an embodiment of the present invention;

[0023] Figure 7 is a circuit diagram of Example 6 of an H-bridge motor braking circuit provided by an embodiment of the present invention;

[0024] Figure 8 It is a control flow chart of an H-bridge motor braking circuit provided by an embodiment of the present invention.

[0025] The reference numerals are as follows:

[0026] 1. Controller, 2. Motor, 3. H-bridge drive circuit, 4. Adjustable voltage unit. DETAILED DESCRIPTION

[0027] The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments.

[0028] Example 1

[0029] See also Figure 1 , 8 As shown, an H-bridge motor braking circuit provided by the present invention includes a controller 1, a motor 2, an H-bridge driving circuit 3 and an adjustable voltage unit 4. The H-bridge driving circuit 3 includes a first switch unit, a second switch unit, a third switch unit and a fourth switch unit respectively electrically connected to the controller 1. The first switch unit and the second switch unit are respectively electrically connected to the positive pole of the motor 2, and the third switch unit and the fourth switch unit are respectively electrically connected to the negative pole of the motor 2. At least one adjustable voltage unit 4 is provided between the controller 1 and the H-bridge driving circuit 3. The adjustable voltage unit 4 is used to adjust the gate drive voltage of at least one switch unit.

[0030] The gate drive voltage of at least one switch unit is adjusted by the adjustable voltage unit 4. When the motor 2 operates normally, the switch tube of the switch unit operates in the saturation area. When the motor is braked, the gate drive voltage of at least one switch unit is reduced so that the switch tube of the switch unit operates in the linear amplification area to increase the resistance of the switch tube, consume the current in the motor generating state, and reduce the generated reverse electromotive force.

[0031] Specifically, the first switch unit and the third switch unit are electrically connected to the DC voltage Vbus respectively. The second switch unit and the fourth switch unit are both grounded through a third resistor.

[0032] Specifically, the first switch unit, the second switch unit, the third switch unit and the fourth switch unit respectively include a MOS switch tube Q and a diode D connected in series between the source and the drain of the MOS switch tube. The gate of the MOS switch tube of the first switch unit is electrically connected to the controller 2, the source of the MOS switch tube of the first switch unit is electrically connected to the second switch unit, and the drain of the MOS switch tube of the first switch unit is electrically connected to the third switch unit.

[0033] Figure 2 FIG. 4 is a circuit diagram of a motor forward braking when the adjustable voltage unit 4 includes an operational amplifier.

[0034] like Figure 2 As shown, the first switch unit and the third switch unit are connected to the high-level output end of the controller 1; the second switch unit is connected to the adjustable voltage unit 4, the power supply end of the operational amplifier is electrically connected to the PWM (Pulse Width Modulation) output port of the controller 1, the adjustable voltage unit 4 includes an operational amplifier, a first resistor and a second resistor, the power supply end of the operational amplifier is electrically connected to the low-level output end of the controller, the same-direction input end of the operational amplifier is electrically connected to the DAC (Digital to Analog Converter) output port of the controller, a first resistor is connected in series between the reverse input end and the output end of the operational amplifier, the reverse input end of the operational amplifier is grounded through the second resistor, the operational amplifier is configured in the same-direction amplification mode, and the output end of the operational amplifier is electrically connected to the gate of the second switch unit.

[0035] The use of adjustable gate drive voltage expands the applicable types of switch tubes. By setting different drive voltages, the braking speed can be adjusted to achieve controllable absorption of reverse current.

[0036] Specifically, the voltage range of the DAC output port is 0-3.3V.

[0037] Example 2

[0038] Figure 3 The circuit diagram of the motor reverse braking when the adjustable voltage unit includes an operational amplifier.

[0039] This embodiment makes one of the optimized designs based on the above embodiment, such as Figure 3 As shown, the fourth switch unit is connected to the adjustable voltage unit 4, and the output end of the operational amplifier is electrically connected to the gate of the fourth switch unit.

[0040] Example 3

[0041] Figure 4 The circuit diagram of the motor forward and reverse braking when the adjustable voltage unit includes an operational amplifier.

[0042] This embodiment makes one of the optimized designs based on the above embodiment, such as Figure 4 As shown, the second switch unit and the fourth switch unit are both connected to the adjustable voltage unit 4, and the output ends of the two operational amplifiers are electrically connected to the gates of the second switch unit and the fourth switch unit respectively.

[0043] Example 4

[0044] When the VGS(th) of the switch tube used is very small (for example, less than 2.5V@250uA), an emitter follower is used instead of an operational amplifier to achieve voltage regulation. VGS(th) is the turn-on voltage.

[0045] Figure 5 The circuit diagram of the motor forward braking when the adjustable voltage unit includes an emitter follower.

[0046] This embodiment makes one of the optimized designs based on the above embodiment, such as Figure 5 As shown, the second switch unit is connected to an adjustable voltage unit 4, the adjustable voltage unit 4 includes an emitter follower, the emitter follower includes a transistor, the base of the transistor is electrically connected to the second port of the controller 1, the collector of the transistor is electrically connected to the first port of the controller 1, and the emitter of the transistor is electrically connected to the gate of the second switch unit. Specifically, the first port is a PWM output port, the second port is a DAC output port, and the voltage range of the second port is 0-3.3V.

[0047] Example 5

[0048] Figure 6 The circuit diagram of the motor reverse braking when the adjustable voltage unit includes an emitter follower.

[0049] Embodiment Based on the above embodiment, an optimized design is made, such as Figure 6 As shown, the fourth switch unit is connected to an adjustable voltage unit 4, the adjustable voltage unit 4 includes an emitter follower, the emitter follower includes a transistor, the base of the transistor is electrically connected to the second port of the controller 1, the collector of the transistor is electrically connected to the first port of the controller 1, and the emitter of the transistor is electrically connected to the gate of the fourth switch unit.

[0050] Example 6

[0051] Figure 7 The circuit diagram of the motor forward and reverse braking when the adjustable voltage unit includes an emitter follower.

[0052] Embodiment Based on the above embodiment, an optimized design is made, such as Figure 6As shown, the second switch unit and the fourth switch unit are both connected to an adjustable voltage unit 4, the adjustable voltage unit 4 includes an emitter follower, the emitter follower includes a transistor, the base of the transistor is electrically connected to the second port of the controller 1, the collector of the transistor is electrically connected to the first port of the controller 1, and the emitters of the two transistors are electrically connected to the gates of the second switch unit and the fourth switch unit, respectively.

[0053] The present invention can also consume the reverse electromotive force by increasing the gate drive resistance and the switching frequency.

[0054] The above is only a preferred embodiment of the present invention, and the protection scope of the present invention is not limited to the above embodiments. All technical solutions under the concept of the present invention belong to the protection scope of the present invention. It should be pointed out that for ordinary technicians in this technical field, some improvements and modifications without departing from the principle of the present invention should also be regarded as the protection scope of the present invention.

Claims

1. An H-bridge motor braking circuit, characterized in that: The invention comprises a controller (1), a motor (2), an H-bridge drive circuit (3) and an adjustable voltage unit (4); the H-bridge drive circuit (3) comprises a first switch unit, a second switch unit, a third switch unit and a fourth switch unit respectively electrically connected to the controller (1); the first switch unit and the second switch unit are respectively electrically connected to the positive pole of the motor (2); the third switch unit and the fourth switch unit are respectively electrically connected to the negative pole of the motor (2); at least one adjustable voltage unit (4) is provided between the controller (1) and the H-bridge drive circuit (3); the adjustable voltage unit (4) is used to adjust the gate drive voltage of at least one switch unit; The first switch unit and the third switch unit are connected to the high level output terminal of the controller (1); The first switch unit, the second switch unit, the third switch unit and the fourth switch unit respectively include a MOS switch tube and a diode connected in series between the source and the drain of the MOS switch tube; When the motor (2) operates normally, the MOS switch tube of the switch unit operates in a saturation region; when the motor (2) is braked, the gate drive voltage of at least one switch unit is reduced through the adjustable voltage unit (4), so that the MOS switch tube of the switch unit operates in a linear amplification region, thereby increasing the resistance of the switch tube, consuming the current of the motor (2) in a power generation state, and reducing the generated reverse electromotive force.

2. The H-bridge motor braking circuit according to claim 1, characterized in that: The adjustable voltage unit (4) comprises an operational amplifier, a power supply terminal of the operational amplifier is electrically connected to a first port of the controller (1), a non-inverting input terminal of the operational amplifier is electrically connected to a second port of the controller (1), a reverse input terminal of the operational amplifier is grounded, the operational amplifier is configured in a non-inverting amplification mode, and an output terminal of the operational amplifier is electrically connected to a gate of one of the switch units.

3. The H-bridge motor braking circuit according to claim 1, characterized in that: The adjustable voltage unit (4) comprises an emitter follower, the emitter follower comprises a triode, the base of the triode is electrically connected to the second port of the controller (1), the collector of the triode is electrically connected to the first port of the controller (1), and the emitter of the triode is electrically connected to the gate of one of the switch units.

4. The H-bridge motor braking circuit according to claim 2, characterized in that: A first resistor is connected in series between the inverting input terminal and the output terminal of the operational amplifier.

5. The H-bridge motor braking circuit according to claim 2 or 4, characterized in that: The inverting input terminal of the operational amplifier is grounded through a second resistor.

6. The H-bridge motor braking circuit according to claim 2 or 3, characterized in that: The first port is a PWM output port.

7. The H-bridge motor braking circuit according to claim 2 or 3, characterized in that: The second port is a DAC output port.

8. The H-bridge motor braking circuit according to claim 2 or 3, characterized in that: The voltage range of the second port of the controller (1) is 0-3.3V.

9. The H-bridge motor braking circuit according to claim 1, characterized in that: The first switch unit and the third switch unit are electrically connected to a DC voltage Vbus respectively.

10. The H-bridge motor braking circuit according to claim 1, characterized in that: The second switch unit and the fourth switch unit are both grounded via a third resistor.

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