Brushless motor regenerative braking energy recovery circuit

Abstract

According to the brushless motor regenerative braking energy recovery circuit, after a motor is braked, energy is stored to a large capacitor with the capacity large enough, then the large capacitor is discharged for expiration of the motor, low-rotation-speed consumption use and inspiration consumption use in the next respiratory cycle are kept, the recovered energy is fully utilized, the energy is stored and used immediately, intermediate loss is avoided, and the energy recovery efficiency is improved. The power supply chip of the DC-DC power supply circuit of the motor does not work continuously but works intermittently, so that heat can be reduced, excessive heat of a board card chip, an inductor, an MOS and the like is avoided, and the problems that the conventional energy recovery in the market charges a battery after circuit conversion, the circuit is complicated, the conversion efficiency is low, and energy loss is caused, and the power supply chip needs to work continuously are solved. And the heating loss is large.

Description

Technical Field

[0001] The present application relates to the field of motor braking technology, and in particular to a brushless motor feedback braking energy recovery circuit. Background Art

[0002] Motor braking is mainly divided into dynamic braking and regenerative braking. Dynamic braking converts the kinetic energy stored in the motor rotor into electrical energy, which is consumed in the braking of the motor rotor, and the heat converted into heat is easily wasted. Regenerative braking allows the motor to enter the power generation state from the motor state, and can convert mechanical energy into electrical energy for recycling and storage when the motor is braked.

[0003] Conventional energy recovery in the market is to charge the battery after circuit conversion. The circuit is complex and has energy loss caused by low conversion efficiency. In addition, the DC-DC power supply of the motor in the market generally works continuously, resulting in large heat loss. Therefore, it is necessary to consider how to brake the motor and how to reuse the feedback energy of the motor brake with maximum efficiency. Summary of the invention

[0004] The present application provides a brushless motor feedback braking energy recovery circuit, which solves the technical problems that conventional energy recovery on the market is to charge the battery after circuit conversion, the circuit is complex and there is energy loss caused by low conversion efficiency, and the power chip needs to work continuously, resulting in large heat loss.

[0005] In view of this, the present application provides a brushless motor feedback braking energy recovery circuit, the circuit comprising:

[0006] Motor DC-DC power supply circuit, feedback braking boost circuit and energy storage large capacitor circuit;

[0007] The motor DC-DC power supply circuit includes an overcurrent protection module circuit, an overvoltage protection module circuit, an undervoltage protection module circuit and a power chip, and the overcurrent protection module circuit, the overvoltage protection module circuit and the undervoltage protection module circuit are respectively connected to the power chip;

[0008] The feedback braking boost circuit includes a motor driving chip, a BOOST boost chopper circuit and a driving MOS tube, and the motor driving chip BRAEK brake pin PWM chopper control performs feedback braking;

[0009] The energy storage large capacitor circuit includes four capacitors connected in parallel;

[0010] The feedback braking boost circuit is connected to the motor DC-DC power supply circuit, and the motor DC-DC power supply circuit is connected to the power supply end of the brushless motor through the energy storage large capacitor circuit.

[0011] Optionally, the power chip of the motor DC-DC power supply circuit is specifically an LT8390 chip.

[0012] Optionally, the motor driving chip of the feedback braking boost circuit is specifically a DRV8323 chip with integrated Hall commutation.

[0013] Optionally, the BOOST boost chopper circuit specifically includes:

[0014] Energy storage inductor L, freewheeling diode VD, power tube Q and filter capacitor C;

[0015] The first end of the energy storage inductor L is connected to the brushless motor, and the second end of the energy storage inductor L is connected to the positive electrode of the freewheeling diode VD and the drain of the power tube Q respectively;

[0016] The cathode of the freewheeling diode VD is connected to the first end of the filter capacitor C and the anode of the power source E respectively;

[0017] The second end of the filter capacitor C, the negative electrode of the power source E and the source electrode of the power tube Q are respectively connected to the brushless motor.

[0018] Optionally, the brushless motor is specifically a brushless DC motor with Hall 120° distribution, two-phase conduction six-step commutation control, a turbine as a rotor, and a magnet with one pole.

[0019] Optionally, when the output duty cycle of the brake pin of the motor driving chip BRAEK is 100%, energy consumption braking is performed; when the output duty cycle of the brake pin of the motor driving chip BRAEK is not 100%, feedback braking is performed.

[0020] It can be seen from the above technical solutions that the embodiments of the present application have the following advantages:

[0021] In the present application, a brushless motor feedback braking energy recovery circuit is provided. After the motor is braked, energy is stored in a large capacitor with a large enough capacity, and then the large capacitor is used to discharge the energy to the motor for exhalation to maintain low speed consumption and inhalation consumption in the next breathing cycle, so that the recovered energy is fully utilized, stored and used immediately, and intermediate losses are avoided. The power chip of the motor DC-DC power supply circuit does not work continuously, but works intermittently, which can reduce heat and avoid excessive heat generation of board chips, inductors, MOS, etc., which solves the technical problems that conventional energy recovery on the market is to charge the battery after circuit conversion, the circuit is complex and there is energy loss caused by low conversion efficiency, and the power chip needs to work continuously, resulting in large heat loss. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 This is a structural framework diagram of a brushless motor feedback braking energy recovery circuit in an embodiment of the present application;

[0023] Figure 2 : is a circuit structure diagram of a DC-DC power supply circuit for a motor in an embodiment of the present application;

[0024] Figure 3 This is a circuit structure diagram of the first part of the feedback braking boost circuit in the embodiment of the present application;

[0025] Figure 4 This is a circuit structure diagram of the second part of the feedback braking boost circuit in the embodiment of the present application;

[0026] Figure 5 This is a circuit structure diagram of the third part of the feedback braking boost circuit in the embodiment of the present application;

[0027] Figure 6 This is a circuit structure diagram of the fourth part of the feedback braking boost circuit in the embodiment of the present application;

[0028] Figure 7 This is a circuit structure diagram of a BOOST boost chopper circuit of a feedback braking boost circuit in an embodiment of the present application;

[0029] Figure 8 A circuit structure diagram of a large energy storage capacitor circuit in an embodiment of the present application;

[0030] Wherein, the accompanying drawings are marked as follows:

[0031] 101. Motor DC-DC power supply circuit; 102. Feedback braking boost circuit; 103. Large energy storage capacitor circuit; 104. Brushless motor; L, energy storage inductor; VD, freewheeling diode; Q, power tube; C, filter capacitor. DETAILED DESCRIPTION

[0032] In order to enable those skilled in the art to better understand the solution of the present application, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0033] The present application designs a brushless motor feedback braking energy recovery circuit and method, which solves the technical problems that conventional energy recovery on the market is to charge the battery after circuit conversion, the circuit is complex and has energy loss caused by low conversion efficiency, and the power chip needs to work continuously, resulting in large heat loss.

[0034] For easier understanding, see Figure 1 , Figure 1FIG. 1 is a structural framework diagram of a brushless motor feedback braking energy recovery circuit in an embodiment of the present application. Figure 1 As shown, specifically including:

[0035] Motor DC-DC power supply circuit 101, feedback braking boost circuit 102 and energy storage large capacitor circuit 103;

[0036] The motor DC-DC power supply circuit 101 includes an overcurrent protection module circuit, an overvoltage protection module circuit, an undervoltage protection module circuit and a power chip, and the overcurrent protection module circuit, the overvoltage protection module circuit and the undervoltage protection module circuit are respectively connected to the power chip;

[0037] The feedback braking boost circuit 102 includes a motor driving chip, a BOOST boost chopper circuit and a driving MOS tube. The motor driving chip BRAEK brake pin PWM chopper control performs feedback braking;

[0038] The energy storage large capacitor circuit 103 includes four capacitors connected in parallel;

[0039] The feedback braking boost circuit 102 is connected to the motor DC-DC power supply circuit 101 , and the motor DC-DC power supply circuit 101 is connected to the power supply end of the brushless motor 104 through the energy storage large capacitor circuit 103 .

[0040] Furthermore, the brushless motor 104 is specifically a brushless DC motor with a 120° Hall distribution, two-phase conduction and six-step commutation control, a turbine as a rotor, and a magnet with one pole.

[0041] It should be noted that this solution uses a ventilator turbine as the rotor, a brushless DC motor with one pole of the magnet, a 120° Hall distribution, two-phase conduction six-step commutation control, square wave control, and dual closed-loop control of current inner loop and speed outer loop.

[0042] The brushless motor feedback braking energy recovery circuit of this application consists of three parts:

[0043] One is a motor DC-DC power supply circuit 101 with overcurrent, overvoltage and undervoltage protection;

[0044] The second is a feedback brake boost circuit 102 composed of a motor drive chip BRAEK brake pin PWM chopping control, a BOOST boost chopping circuit and a drive MOS tube;

[0045] The third is the energy storage large capacitor circuit 103, which stores energy for recovery and supplies high current for instantaneous inhalation acceleration.

[0046] The power chip of the motor DC-DC power supply circuit 101 is specifically as follows: Figure 2The LT8390 chip shown in the figure has a ±10% voltage error on the FB pin of the LT8390 chip, which can set a suitable output voltage, a suitable current protection threshold, and a suitable soft start time.

[0047] Furthermore, if Figures 3 to 7 As shown, the motor drive chip of the feedback braking boost circuit 102 is specifically as follows Figure 3 The DRV8323 chip with integrated Hall commutation is shown.

[0048] It should be noted that the DRV8323 chip uses Asynchronous 1x PWM Mode SPI, and can use the BRAEK brake pin PWM chopping for feedback braking and energy recovery.

[0049] Among them, when the BRAEK duty cycle is 100%, it is equivalent to the three upper tubes of the wheel being closed and the three lower tubes being fully open, which belongs to the motor winding energy consumption braking, hard braking, and fast braking time. When the BRAEK duty cycle is not 100%, it is equivalent to the three upper tubes of the wheel being closed and the three lower tubes being PWM chopped, which belongs to regenerative braking, adjustable duty cycle and braking current, flexible braking, the larger the duty cycle, the larger the braking current, the faster the braking speed, and the energy can be recovered to the large capacitor on the power supply.

[0050] Brushless DC motor regenerative braking can be achieved in the following two ways:

[0051] One is to add a Boost circuit between the motor drive circuit and the power supply.

[0052] The second is to perform chopping control on the three-phase full-bridge circuit through software to produce a function similar to the Boost circuit.

[0053] The second method does not require additional hardware circuits and does not increase system costs. This solution adopts the second method, BREAK chopping control, the upper tube is fully turned off, and the lower tube is PWM.

[0054] Furthermore, if Figure 7 As shown in the figure, the BOOST boost chopper circuit specifically includes:

[0055] Energy storage inductor L, freewheeling diode VD, power tube Q and filter capacitor C;

[0056] The first end of the energy storage inductor L is connected to the brushless motor, and the second end of the energy storage inductor L is connected to the positive electrode of the freewheeling diode VD and the drain of the power tube Q respectively;

[0057] The cathode of the freewheeling diode VD is connected to the first end of the filter capacitor C and the anode of the power source E respectively;

[0058] The second end of the filter capacitor C, the negative electrode of the power source E and the source electrode of the power tube Q are respectively connected to the brushless motor.

[0059] It should be noted that the Boost chopper circuit is Figure 7 As shown, it is composed of energy storage inductor L, freewheeling diode VD, power tube Q and filter capacitor C;

[0060] Among them, the energy storage inductor L is the motor winding inductance;

[0061] The freewheeling diode VD is a parasitic diode on the motor drive circuit;

[0062] Power tube Q is the lower tube of the motor drive circuit;

[0063] The filter capacitor C is a large capacitor connected in parallel with the motor bus power supply.

[0064] During regenerative braking, the back electromotive force of the phase winding is boosted to charge the large capacitor of the motor bus power supply.

[0065] Furthermore, when the output duty cycle of the brake pin of the motor driving chip BRAEK is 100%, energy consumption braking is performed; when the output duty cycle of the brake pin of the motor driving chip BRAEK is not 100%, feedback braking is performed.

[0066] Based on the brushless motor feedback braking energy recovery circuit provided in the present application, the present application also provides a brushless motor feedback braking energy recovery method, the method comprising:

[0067] When the brushless motor is braking, the power chip stops working, and the duty cycle of the motor driver chip BRAEK brake pin output is non-100%, so that the brushless motor winding back electromotive force PWM chopped and stored in the energy storage large capacitor circuit;

[0068] After current flows into the large energy storage capacitor circuit, the voltage gradually rises to the maximum value, and the large energy storage capacitor is charged and stores energy. The large energy storage capacitor can then be discharged to the brushless motor for power supply, so as to be used for consumption of the brushless motor during the exhalation hold phase of the ventilator and the consumption of the brushless motor during the inhalation phase of the next respiratory cycle.

[0069] During the exhalation hold stage and the inhalation stage, the ventilator powers the brushless motor through a large energy storage capacitor. After the power chip resumes working, the motor DC-DC power supply circuit powers the brushless motor.

[0070] It should be noted that by connecting a large capacitor to the motor power supply, the large capacitor is repeatedly charged to store energy and discharged to consume energy, thereby efficiently utilizing the recovered energy.

[0071] When the motor brakes from inhalation to exhalation or other times when braking is required, the DC-DC power supply chip stops working and the BRAEK brake pin gives a non-100% PWM duty cycle, which is equivalent to turning off the three upper tubes of the motor and PWM chopping the three lower tubes. Similar to a boost circuit, the PWM chopping of the motor winding back electromotive force is stored in a large capacitor, current flows into the large capacitor, and the voltage of the large capacitor increases to the maximum. The large capacitor charges and stores energy, and then only the large capacitor discharges to maintain low speed consumption for exhalation and inhalation consumption in the next breathing cycle.

[0072] The motor consumes power when the exhalation is maintained and the inhalation pressure rises, current flows out of the large capacitor, and the voltage of the large capacitor drops. Until the DC-DC power chip resumes working, the large capacitor is recharged and the motor is powered again. This cycle repeats in each breathing cycle.

[0073] In summary, after the motor is braked, the energy is stored in a large capacitor with a large enough capacity, and then the large capacitor is used to discharge the motor to maintain low speed consumption during exhalation and inhalation consumption during the next breathing cycle, making full use of the recovered energy, storing and using it immediately, and avoiding intermediate losses. In addition, the motor DC-DC power supply chip does not work continuously, but intermittently, which can reduce heat generation and avoid excessive heat generation of board chips, inductors, MOS, etc.

[0074] Furthermore, it also includes:

[0075] The capacitance value of the large energy storage capacitor is determined according to the capacitor storage energy formula.

[0076] Furthermore, the capacitor storage energy formula is specifically:

[0077]

[0078] As Figure 8 As shown, the energy storage capacitor is 4 10000uf / 50V capacitors as an example:

[0079] 40000uF=40mF=0.04F;

[0080] Q = CU = 0.04F * 28V = 1.12 Coulomb;

[0081] Q = It = 10A * 0.1s = 1 coulomb;

[0082] 1.12 coulomb / 10A=0.112s;

[0083] A 40000uF electrolytic capacitor can provide a load current of 10A for 0.112s;

[0084] 1.12 coulomb / 5A=0.224s;

[0085] A 40000uF electrolytic capacitor can provide a load current of 5A for 0.224s.

[0086] In the embodiment of the present application, a brushless motor feedback braking energy recovery circuit and method are provided. After the motor is braked, energy is stored in a large capacitor with a large enough capacity, and then the large capacitor is used to discharge the energy to the motor for exhalation to maintain low speed consumption and inhalation consumption in the next breathing cycle, so that the recovered energy is fully utilized, which can be stored and used immediately to avoid intermediate losses. The power chip of the motor DC-DC power supply circuit does not work continuously but intermittently, which can reduce heat and avoid excessive heat generation of board chips, inductors, MOS, etc., which solves the technical problems that conventional energy recovery on the market is to charge the battery after circuit conversion, the circuit is complex and there is energy loss caused by low conversion efficiency, and the power chip needs to work continuously, resulting in large heat loss.

[0087] As described above, the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A brushless motor feedback braking energy recovery circuit, characterized in that: include: Motor DC-DC power supply circuit, feedback braking boost circuit and energy storage large capacitor circuit; The motor DC-DC power supply circuit includes an overcurrent protection module circuit, an overvoltage protection module circuit, an undervoltage protection module circuit and a power chip, and the overcurrent protection module circuit, the overvoltage protection module circuit and the undervoltage protection module circuit are respectively connected to the power chip; The feedback braking boost circuit includes a motor driving chip, a BOOST boost chopper circuit and a driving MOS tube, and the motor driving chip BRAEK brake pin PWM chopper control performs feedback braking; The energy storage large capacitor circuit includes four capacitors connected in parallel; The feedback braking boost circuit is connected to the motor DC-DC power supply circuit, and the motor DC-DC power supply circuit is connected to the power supply end of the brushless motor through the energy storage large capacitor circuit.

2. The brushless motor feedback braking energy recovery circuit according to claim 1, characterized in that: The power chip of the motor DC-DC power supply circuit is specifically an LT8390 chip.

3. The brushless motor feedback braking energy recovery circuit according to claim 1, characterized in that: The motor driving chip of the feedback braking boost circuit is specifically a DRV8323 chip with integrated Hall commutation.

4. The brushless motor feedback braking energy recovery circuit according to claim 3, characterized in that: The BOOST boost chopper circuit specifically includes: Energy storage inductor (L), freewheeling diode (VD), power tube (Q) and filter capacitor (C); The first end of the energy storage inductor (L) is connected to the brushless motor, and the second end of the energy storage inductor (L) is respectively connected to the positive electrode of the freewheeling diode (VD) and the drain electrode of the power tube (Q); The cathode of the freewheeling diode (VD) is respectively connected to the first end of the filter capacitor (C) and the anode of the power source (E); The second end of the filter capacitor (C), the negative electrode of the power source (E) and the source electrode of the power tube (Q) are respectively connected to the brushless motor.

5. The brushless motor feedback braking energy recovery circuit according to claim 4, characterized in that: The brushless motor is specifically a brushless DC motor that adopts 120° Hall distribution, two-phase conduction six-step commutation control, and a turbine as a pair of poles of the rotor magnet.

6. The brushless motor feedback braking energy recovery circuit according to claim 1, characterized in that: When the output duty cycle of the brake pin of the motor driving chip BRAEK is 100%, energy consumption braking is performed; when the output duty cycle of the brake pin of the motor driving chip BRAEK is not 100%, feedback braking is performed.

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