Electric vehicle brushless motor controller

Abstract

The invention relates to an electric vehicle brushless motor controller, which comprises a PIC16F72 single-chip microcomputer, a current detection module, a power supply module, a brake module, a function module, an overcurrent protection module and an induction module, and is characterized in that the PIC16F72 single-chip microcomputer is connected with the current detection module, the power supply module, the function module, the overcurrent protection module and the induction module; the current detection module comprises a comparator M1 and a resistor RG23. The negative input end of the comparator M1 is connected with one end of a resistor RG15. The positive input end of the comparator M1 is connected with one end of a resistor RG19 and one end of a resistor RG55; the output end of the comparator M1 is connected with a second pin of the PIC16F72 single chip microcomputer; one end of the resistor RG23 is connected with the output end of the comparator M1, the other end of the resistor RG23 is connected with the other end of the resistor RG15 and the other end of the resistor RG19, and the other end of the resistor RG55 is grounded.

Description

Technical Field

[0001] The invention relates to the technical field of electric vehicle controllers, in particular to an electric vehicle brushless motor controller. Background Art

[0002] The brushless motor for electric vehicles is currently the most popular power source for electric vehicles. Brushless motors are widely used for their longevity and maintenance-free characteristics compared to brushed motors. However, since they use direct current but no brushes for commutation, their commutation control is much more complicated than that of brushed motors. At the same time, since the load of electric vehicles is extremely unstable and batteries are used as power sources, the protection of the controller itself and the protection of the motor and power supply all put forward more requirements on the controller.

[0003] Since the advent of brushless motors for electric vehicles, the development of their controllers has been divided into two stages: the first stage is a pure hardware circuit controller composed mainly of dedicated brushless motor control chips. This circuit is relatively simple, and the representative control chip is Motorola's MC33035; the second stage is a control chip based on MCU; however, the MC33035 control chip is limited by the early manufacturing process and faces challenges in performance improvement, temperature stability and driving capability limitations; while the MCU control chip needs to deal with issues such as power consumption and performance balance, customization requirements, safety and increased design costs; these problems need to be solved through technological progress and innovation. Summary of the invention

[0004] The technical problem to be solved by the present invention is to provide a brushless motor controller for an electric vehicle, which can achieve a more flexible and more functional control effect.

[0005] The technical solution adopted by the present invention to solve its technical problem is:

[0006] An electric vehicle brushless motor controller comprises a PIC16F72 single-chip microcomputer, a current detection module, a power module, a brake module, a functional module, an overcurrent protection module and a sensing module, wherein the PIC16F72 single-chip microcomputer is respectively connected to the current detection module, the power module, the functional module, the overcurrent protection module and the sensing module;

[0007] The current detection module includes a comparator M1 and a resistor RG23, wherein the negative input end of the comparator M1 is connected to one end of the resistor RG15; the positive input end of the comparator M1 is connected to one end of the resistor RG19 and one end of the resistor RG55; the output end of the comparator M1 is connected to the second pin of the PIC16F72 microcontroller;

[0008] One end of the resistor RG23 is connected to the output end of the comparator M1 , the other end of the resistor RG23 is connected to the other end of the resistor RG15 and the other end of the resistor RG19 , and the other end of the resistor RG55 is grounded.

[0009] The power supply module includes a three-terminal voltage regulator LM317, a three-terminal voltage regulator L78L05 and a capacitor C20, the three-terminal voltage regulator LM317 outputs a constant +13.5V voltage, the three-terminal voltage regulator L78L05 inputs a constant +13.5V voltage and outputs a constant +5V voltage;

[0010] The input end of the three-terminal voltage regulator LM317 is connected to one end of the resistor R1, one end of the resistor R80 and the positive end of the capacitor C4, the negative end of the capacitor C4 is connected to one end of the resistor R2, the other end of the resistor R2 is connected to one end of the resistor R36, the other end of the resistor R36 is connected to the other end of the resistor R80 and the output end of the three-terminal voltage regulator LM317;

[0011] The input end of the three-terminal voltage regulator L78L05 is connected to one end of the capacitor C18, one end of the resistor R75 and one end of the resistor R77, the other end of the capacitor C18 is connected to one end of the capacitor C20, and the output end of the three-terminal voltage regulator L78L05 is connected to the other end of the resistor R75, the other end of the resistor R77 and the other end of the capacitor C20;

[0012] The output end of the three-terminal voltage regulator L78L05 and the output end of the three-terminal voltage regulator LM317 are both connected to the 20th pin of the PIC16F72 microcontroller, both ends of the resistor R2 and one end of the capacitor C18 are grounded, and the output end of the three-terminal voltage regulator LM317 is connected to the input end of the three-terminal voltage regulator L78L05.

[0013] The overcurrent protection module includes a comparator M2, wherein the negative input end of the comparator M2 is connected to one end of the resistor RG22, the positive input end is connected to one end of the resistor RG29 and one end of the resistor RG30, and the output end is connected to the 21st pin of the PIC16F72 single-chip computer;

[0014] The other end of the resistor RG22 is connected to one end of the resistor RG27 and one end of the resistor RG25. The other ends of the resistor RG27, RG25 and RG29 are grounded. The other end of the resistor RG30 is connected to the output end of the comparator M2.

[0015] The brake module includes a terminal P3 and a terminal P4, wherein the first pin of the terminal P3 is connected to one end of a resistor RG28, the second pin is grounded, the other end of the resistor RG28 is connected to one end of a resistor RG32 and one end of a capacitor CK8, and the other end of the capacitor CK8 is connected to one end of a resistor RG34;

[0016] The first pin of the terminal P4 is connected to the cathode of the diode DI4 and one end of the capacitor CK11, the anode of the diode DI4 is connected to the fifth pin of the PIC16F72 microcontroller, and the third pin of the terminal P4 is connected to the other end of the resistor RG32 and the other end of the resistor RG34;

[0017] The second pin of P4, the other end of the capacitor CK8 and the other end of the capacitor CK11 are grounded.

[0018] The functional module includes a terminal P6 and a terminal P7, wherein the first pin of the terminal P6 is grounded, the second pin of the terminal P6 is connected to one end of a resistor RG53, the other end of the resistor RG53 is connected to one end of a resistor RG48, the other end of the resistor RG48 is connected to one end of a resistor RG46, one end of a capacitor CK13 and a positive electrode of a diode DI6, the negative electrode of the diode DI6 is connected to one end of a resistor RG49 and one end of a resistor RG50, the other end of the resistor RG49 is connected to the third pin of the terminal P7 and the sixth pin of a PIC16F72 single-chip computer, the second pin of the terminal P7 is connected to the eleventh pin of the PIC16F72 single-chip computer, and the other end of the resistor RG50 is connected to the first pin of the terminal P7 and the twelfth pin of the PIC16F72 single-chip computer;

[0019] The other end of the capacitor CK13 and the other end of the resistor RG46 are grounded.

[0020] The sensing module includes a terminal P8 and a diode DI9, the first pin of the P8 is connected to one end of a resistor RG69 and one end of a resistor RG75, and the other end of the resistor RG69 is connected to one end of a capacitor CK18;

[0021] The second pin of the terminal P8 is connected to one end of a resistor RG71 and one end of a resistor RG74, and the other end of the resistor RG71 is connected to one end of a capacitor CP16;

[0022] The third pin of the terminal P8 is connected to one end of a resistor RG72 and one end of a resistor RG73, and the other end of the resistor RG72 is connected to one end of a capacitor CP15;

[0023] The fifth pin of the terminal P8, the other end of the capacitor CK18, the other end of the capacitor CP16 and the other end of the capacitor CP15 are all grounded;

[0024] The other end of the resistor RG69 is also connected to the 15th pin of the PIC16F72 single-chip microcomputer, the other end of the resistor RG71 is also connected to the 17th pin of the PIC16F72 single-chip microcomputer, and the other end of the resistor RG72 is also connected to the 16th pin of the PIC16F72 single-chip microcomputer;

[0025] The other end of the resistor RG73 , the other end of the resistor RG74 , and the other end of the resistor RG75 are all connected to the anode of the diode DI9 .

[0026] The beneficial effects of the present invention are: by integrating the latest MCU technology, a more flexible and more functional control effect can be achieved; this includes increasing the data transmission rate, reducing latency to enhance the real-time performance of the system, and through high-precision step angle control technology. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is the circuit schematic diagram of the controller;

[0028] Figure 2 It is the circuit schematic diagram of the current detection module;

[0029] Figure 3 This is the circuit schematic diagram of the power module;

[0030] Figure 4 This is the circuit schematic diagram of the overcurrent protection module;

[0031] Figure 5 This is the circuit schematic diagram of the brake module;

[0032] Figure 6 It is the circuit schematic diagram of the functional module;

[0033] Figure 7 This is the circuit schematic diagram of the sensing module;

[0034] Figure 8 It is a schematic diagram of synchronous freewheeling;

[0035] Fig. 9 This is the circuit diagram of the A-phase drive circuit. DETAILED DESCRIPTION

[0036] Example 1

[0037] The present invention is further described below in conjunction with the accompanying drawings and embodiments.

[0038] like Figures 1 to 7 As shown, a brushless motor controller for an electric vehicle includes a PIC16F72 single-chip microcomputer, a current detection module, a power module, a brake module, a functional module, an overcurrent protection module and a sensing module, wherein the PIC16F72 single-chip microcomputer is respectively connected to the current detection module, the power module, the functional module, the overcurrent protection module and the sensing module;

[0039] The current detection module includes a comparator M1 and a resistor RG23, wherein the negative input end of the comparator M1 is connected to one end of the resistor RG15; the positive input end of the comparator M1 is connected to one end of the resistor RG19 and one end of the resistor RG55; the output end of the comparator M1 is connected to the second pin of the PIC16F72 microcontroller;

[0040] One end of the resistor RG23 is connected to the output end of the comparator M1 , the other end of the resistor RG23 is connected to the other end of the resistor RG15 and the other end of the resistor RG19 , and the other end of the resistor RG55 is grounded.

[0041] U3A is an amplifier circuit, which amplifies the current signal sampled by the constantan wire R55 by 6.5 times and sends it to the microcontroller. The earliest design connected a 0.1μF capacitor in parallel with R23 to form a low-pass amplifier. Later, in order to better detect the current in real time, the capacitor was removed, so that the actual changes of the amplified voltage and current are basically the same, so that the MCU sampling value is closer to the actual value.

[0042] The other end of resistor RG15 provides a +5V voltage.

[0043] The power supply module includes a three-terminal voltage regulator LM317, a three-terminal voltage regulator L78L05 and a capacitor C20, the three-terminal voltage regulator LM317 outputs a constant +13.5V voltage, the three-terminal voltage regulator L78L05 inputs a constant +13.5V voltage and outputs a constant +5V voltage;

[0044] The input end of the three-terminal voltage regulator LM317 is connected to one end of the resistor R1, one end of the resistor R80 and the positive end of the capacitor C4, the negative end of the capacitor C4 is connected to one end of the resistor R2, the other end of the resistor R2 is connected to one end of the resistor R36, the other end of the resistor R36 is connected to the other end of the resistor R80 and the output end of the three-terminal voltage regulator LM317;

[0045] The input end of the three-terminal voltage regulator L78L05 is connected to one end of the capacitor C18, one end of the resistor R75 and one end of the resistor R77, the other end of the capacitor C18 is connected to one end of the capacitor C20, and the output end of the three-terminal voltage regulator L78L05 is connected to the other end of the resistor R75, the other end of the resistor R77 and the other end of the capacitor C20;

[0046] The output end of the three-terminal voltage regulator L78L05 and the output end of the three-terminal voltage regulator LM317 are both connected to the 20th pin of the PIC16F72 microcontroller, both ends of the resistor R2 and one end of the capacitor C18 are grounded, and the output end of the three-terminal voltage regulator LM317 is connected to the input end of the three-terminal voltage regulator L78L05.

[0047] The overcurrent protection module includes a comparator M2, wherein the negative input end of the comparator M2 is connected to one end of the resistor RG22, the positive input end is connected to one end of the resistor RG29 and one end of the resistor RG30, and the output end is connected to the 21st pin of the PIC16F72 single-chip computer;

[0048] The other end of the resistor RG22 is connected to one end of the resistor RG27 and one end of the resistor RG25 (the other end of the resistor RG22 provides a +5V voltage), the other end of the resistor RG27, the other end of the resistor RG25 and the other end of the resistor RG29 are grounded, and the other end of the resistor RG30 is connected to the output end of the comparator M2.

[0049] U3B is a comparator connection method, and is actually a comparator. The normal current will never cause the comparator to flip. When the current suddenly increases to a certain level due to some reason, the comparator flips and triggers the external interrupt of the microcontroller. The microcontroller will completely shut down the output of the motor and enter a protection state to prevent the fault from further expanding.

[0050] Why is the amplifier gain so small? If the gain is larger, the digital number after AD conversion of the microcontroller will be relatively large, and the resolution can be made higher. Why not? Because the frequency response of LM358 is not high enough, the square wave of 15KHZ (the working frequency of PWM is about 15.6K) becomes a trapezoidal wave after being amplified by 358. At present, the sampling of the current peak should take the upper side of the trapezoidal wave. If the gain is too large, the upper side of the trapezoidal wave will become very narrow, making it difficult for the microcontroller to sample, or even sampling errors, such as sampling the hypotenuse of the trapezoidal wave, and thus cannot correctly reflect the actual size of the current, which will lead to the disorder of current control. Therefore, the gain is small to ensure the accuracy of the sampling position.

[0051] The brake module includes a terminal P3 and a terminal P4, wherein the first pin of the terminal P3 is connected to one end of a resistor RG28, the second pin is grounded, the other end of the resistor RG28 is connected to one end of a resistor RG32 and one end of a capacitor CK8, and the other end of the capacitor CK8 is connected to one end of a resistor RG34;

[0052] The first pin of the terminal P4 is connected to the cathode of the diode DI4 and one end of the capacitor CK11, the anode of the diode DI4 is connected to the fifth pin of the PIC16F72 microcontroller, and the third pin of the terminal P4 is connected to the other end of the resistor RG32 and the other end of the resistor RG34;

[0053] The second pin of P4, the other end of the capacitor CK8 and the other end of the capacitor CK11 are grounded.

[0054] The handle outputs a voltage in the range of 1.2-4.2V, which is input to the microcontroller for processing after RC filtering. The handle requires a 5V power supply to work.

[0055] Motor rotor position sensor input part: Since the sensor is installed inside the motor and adopts an open-circuit output method, in addition to providing a 5V power supply, each sensor must be connected to a pull-up resistor, and its output signal must be filtered by resistance and capacitance to resist interference. At the same time, a diode is connected to the power supply and a thin copper film is used as a fuse to prevent the high voltage from being reversed after the motor phase line and the Hall signal line are short-circuited, which may damage other parts on the board.

[0056] Brake signal input: Since the brake signal switch often shares a switch with the brake light, and the brake voltage of each manufacturer is not uniform, a diode must be connected to prevent high voltage from entering. The high-level input part must work normally when the input is 8-50V.

[0057] The functional module includes a terminal P6 and a terminal P7, wherein the first pin of the terminal P6 is grounded, the second pin of the terminal P6 is connected to one end of a resistor RG53, the other end of the resistor RG53 is connected to one end of a resistor RG48, the other end of the resistor RG48 is connected to one end of a resistor RG46, one end of a capacitor CK13 and the positive electrode of a diode DI6, the negative electrode of the diode DI6 is connected to one end of a resistor RG49 and one end of a resistor RG50 (the negative electrode of the diode DI6 provides a +5V voltage), the other end of the resistor RG49 is connected to the third pin of the terminal P7 and the sixth pin of the PIC16F72 single-chip computer, the second pin of the terminal P7 is connected to the eleventh pin of the PIC16F72 single-chip computer, and the other end of the resistor RG50 is connected to the first pin of the terminal P7 and the twelfth pin of the PIC16F72 single-chip computer;

[0058] The other end of the capacitor CK13 and the other end of the resistor RG46 are grounded.

[0059] The sensing module includes a terminal P8 and a diode DI9, the first pin of the P8 is connected to one end of a resistor RG69 and one end of a resistor RG75, and the other end of the resistor RG69 is connected to one end of a capacitor CK18;

[0060] The second pin of the terminal P8 is connected to one end of a resistor RG71 and one end of a resistor RG74, and the other end of the resistor RG71 is connected to one end of a capacitor CP16;

[0061] The third pin of the terminal P8 is connected to one end of a resistor RG72 and one end of a resistor RG73, and the other end of the resistor RG72 is connected to one end of a capacitor CP15;

[0062] The fifth pin of the terminal P8, the other end of the capacitor CK18, the other end of the capacitor CP16 and the other end of the capacitor CP15 are all grounded;

[0063] The other end of the resistor RG69 is also connected to the 15th pin of the PIC16F72 single-chip microcomputer, the other end of the resistor RG71 is also connected to the 17th pin of the PIC16F72 single-chip microcomputer, and the other end of the resistor RG72 is also connected to the 16th pin of the PIC16F72 single-chip microcomputer;

[0064] The other end of the resistor RG73 , the other end of the resistor RG74 , and the other end of the resistor RG75 are all connected to the anode of the diode DI9 .

[0065] The 4th pin of P8 and the cathode of diode DI9 both provide a +5V voltage.

[0066] Example 2

[0067] Take PIC16F72 as the intelligent control center and the 350W complete circuit as an example.

[0068] The circuit can be roughly divided into five parts: 1. Power supply stabilization and supply part; 2. Signal input and preprocessing part; 3. Intelligent signal processing and control part; 4. Drive control signal preprocessing part; 5. Power drive switch part.

[0069] The PIC16F72 is the intelligent processing and control part of the microcontroller, because other circuits serve it or are controlled by it.

[0070] External resources of PIC16F72: This microcontroller has 28 pins. Excluding power, reset, oscillator, etc., there are a total of 22 reusable IO ports. Pin 13 is the CCP1 output port, which can output an adjustable PWM signal with a maximum resolution of 10BIT. There are also 5 AD analog-to-digital conversion input ports AN0-AN4, which can provide voltage detection for external circuits, and an external interrupt input pin to handle emergencies.

[0071] The PIC16F72 microcontroller is also connected to the drive control signal preprocessing part, which is synthesized by two signals: PWM signal and phase logic switch signal, power switch part: the power switch part is a three-phase switch composed of three groups of half-bridge switches, which is used to change the power-on sequence and power-on direction of the motor coil. The power tube connected to the positive phase of the power supply is generally called the upper bridge, and the power tube connected to the power ground is called the lower bridge. The phase logic switch signal of the upper bridge is provided by A+, B+, and C+. These three control signals must be synthesized with the PWM signal to control the corresponding upper bridge. The phase logic switch signal of the lower bridge is provided by A-, B-, and C-, which is basically used directly to control the switch of the lower bridge; a 2.2K-10K resistor is connected to the ground on these six pins of the microcontroller to prevent the microcontroller from being reset. Since these pins are in a high-impedance state, interference signals may be introduced, causing the subsequent logic circuit to malfunction.

[0072] In fact, these circuits are all designed to achieve one function: synchronous freewheeling, such as Figure 8 As shown, assuming that the A-phase upper bridge and the C-phase lower bridge are powered on at this time, when the PWM duty cycle of the A-phase upper bridge does not reach 100%, the current through the motor coil is intermittent, but when the upper bridge is closed, since the motor coil is an inductor, a self-inductance back electromotive force will definitely appear on the coil. This back electromotive force must maintain the direction of the coil current unchanged. Since the A-phase upper bridge has been closed, this current will pass through the C-phase lower bridge that was originally turned on, and the freewheeling diode of the A-phase lower bridge will continue to flow, as shown in Figure 1. Figure 4 ;When the total current is small, the self-inductance current is not large, but when the total current is large, the energy stored in the coil increases, and the self-inductance current will also be quite large. The voltage drop of the MOSFET's freewheeling diode itself is about 0.7-1V. When the self-inductance current passing through is large, the power consumption will be quite large. Assuming the self-inductance current is 10A, the diode voltage drop is 0.7V, and the power consumption is 7W. Obviously, the heat generation is quite large, and the lower bridge will become very hot. If the lower bridge is turned on at this time, the self-inductance current will go directly from the MOSFET channel (the current can flow in both directions when the MOSFET is turned on), and assuming that the MOSFET on-resistance RDSON=10mΩ, the power consumption will become 1W at 10A. In theory, the power consumption of the lower bridge can be greatly reduced, thereby reducing the temperature rise; but in reality, since the upper and lower bridges need a dead zone when cross-conducting to avoid the power supply short circuit caused by the double tube direct conduction, this effect will be discounted, but the effect is still very obvious. This is also the reason why many products use better tubes for the lower bridge.

[0073] like Fig. 9As shown, taking phase A as an example, the implementation process of the synchronous freewheeling function is explained. When the logic switch signal "A+" of direction A is high, the upper bridge of phase A is driven by the "PWM" signal. When the whole machine current is small, the PV signal is high. Regardless of the levels of the other two input pins of the NOR gate U3C, its output is always low. Therefore, at this time, the NOR gate U2B is only controlled by the "A-" signal. The "A-" signal is the logic switch of the lower bridge. It is set high only when the lower bridge needs to be turned on, and it is usually low. When the whole machine current is relatively large, and the PWM duty cycle is less than 100%, the A-phase upper bridge is turned off during the PWM gap, resulting in a large inductive current in the motor coil. The inductive current is discharged through the lower bridge of the other phase and the diode of the A-phase lower bridge. In order to reduce the power consumption of the diode, the A-phase lower bridge MOSFET should be turned on to reduce the voltage drop. At this time, the microcontroller pulls the "PV" signal end low. Under the joint action of the PV signal and the reversed "A+" signal, the "PWM-" signal is transmitted to U2B through U3C. At this time, since "A-" is low, U2B is controlled by the "PWM-" signal, and the lower bridge MOSFET is turned on during the gap when the PWM signal is turned off. When the "A+" signal is low, the "PWM-" signal does not affect the lower bridge, ensuring the correct logic of the lower bridge without misleading.

[0074] The power switch of the upper bridge can be made directly with P-channel MOSFET, which will make the driving circuit much simpler. However, P-channel power MOSFET is expensive and difficult to buy. In order to save costs, it can only be replaced by N-channel. However, when the N-channel MOSFET is turned on, the voltage of its gate G must be more than 10V higher than the source S to ensure full conduction. So when the upper bridge is turned on, assuming that the power supply voltage is 48V, the voltage of the upper bridge G must be 12V higher than the power supply voltage, that is, greater than 60V. But how to get a driving voltage higher than the power supply voltage? Generally, the driving signal can be coupled by a transformer, and the charge pump can be used to provide high voltage. Here, a "high-voltage floating gate drive circuit" is used to drive the upper bridge.

[0075] This is the key to the entire drive. The positive pole of C5 is connected to a 13.5V power supply (actually around 13.5V) through a diode, and the negative pole is strangely connected to the phase line of the motor and connected to the source of the MOSFET V1 it drives. When the motor is not moving, all MOSFETs are turned off. At this time, C5 is charged to close to 13.5V through diode D1 and resistor R40. When the composite signal of A+ and PWM makes the 3rd pin of U4A output a high level, q1 is turned on to drive t1 to be turned on, so that the voltage of more than 12V will be added to the gate of V1 to turn on V1, and the power supply voltage is added to the load when V1 is turned on, that is, the source voltage of V1 will increase to 48V. At this time, since C5 is fully charged, the voltage on C5 is still 12V, so t1 can be maintained on and the voltage of the gate of V1 can always be kept higher than VCC, so that the gate of V1 seems to float with the floating source voltage, so it is called "floating gate drive". At this time, if the 3rd pin of U4A is always maintained at a high level, after the capacitor between capacitor k1 and MOSFET itself GS is fully charged, the stored charge on C5 is mainly discharged through the BE junction of t1 and resistor a1 to transistor q1 (because diode D7 is in a forward biased state at this time, the BE junction of t2 is reverse biased and cut off, so t2 does not participate in the discharge). If C5 is large enough, the driving voltage of V1 can be guaranteed to be within a reasonable range for a considerable period of time. Here, b1 is placed on the emitter of q1 to form an approximately constant current driving circuit to ensure that when the positive voltage of C5 rises very high, the discharge current through transistor q1 will not be too large and cause the capacitor to be discharged quickly. When the 3rd pin of U4A outputs a low level, q1 and t1 are quickly closed, t2 starts to conduct, and the accumulated charge of k1 and the gate itself is quickly discharged, V1 is closed, and at this time, since one of the other two groups of lower bridges is maintained in the on state, capacitor C5 will be quickly charged through the motor winding and the lower bridge to replenish energy and prepare for the next cycle.

[0076] From the above process, it can be seen that the charge amount of capacitor C5 should be as large as possible. However, if the capacitance is large, the diode may not have enough time to charge the capacitor. If the capacitance is small, the conduction time cannot be guaranteed. Therefore, this drive cannot keep V1 in the on state for a long time. This is also one of the reasons why the PWM signal must be coupled to the upper bridge.

[0077] It stands to reason that in order to reduce switching losses, MOSFET used as a power switch should be avoided from working in the amplification state as much as possible. According to this principle, the voltage level driving the MOSFET should rise and fall quickly, and the faster the better. However, resistors e1 and e2 and capacitors k1 and k2 are added to this circuit. The role of these four components here is obviously contrary to the principle of fast rise and fast fall. In fact, the role of these four parts in the circuit is indeed to intentionally slow down the turn-on speed of the MOSFET, making the rising edge of the voltage waveform driving the MOSFET not so steep. Why do we do this?

[0078] This needs to be seen from the structure of MOSFET. There is an inter-electrode capacitance between each electrode of MOSFET itself, and this capacitance is called Miller capacitance. In the current circuit with upper and lower bridges similar to push-pull structure, when the upper bridge is turned on, the voltage of the drain of the lower bridge rises sharply. This voltage change will be transmitted to the gate of the lower bridge through the Miller capacitance of the lower bridge. The speed at which the drain voltage of the lower bridge increases when the upper bridge is turned on is represented by Δv / Δt. When Δv / Δt is large enough, the charge transmitted to the gate of the lower bridge will accumulate to the point where the lower bridge is turned on, which will cause the upper and lower bridges to directly short-circuit the power supply. The simplest way to solve this problem is to slow down the opening of the upper and lower bridges, so RC delay is added, and the k1 and k2 here also have the effect of absorbing part of the impulse voltage.

[0079] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Technical equivalents, improvements, etc. in the art should all be included in the protection of the present invention.

Claims

1. A brushless motor controller for an electric vehicle, comprising a PIC16F72 single-chip microcomputer, a current detection module, a power module, a brake module, a functional module, an overcurrent protection module and a sensing module, characterized in that; The PIC16F72 single chip microcomputer is respectively connected with the current detection module, the power module, the functional module, the overcurrent protection module and the sensing module; The current detection module includes a comparator M1 and a resistor RG23, wherein the negative input end of the comparator M1 is connected to one end of the resistor RG15; the positive input end of the comparator M1 is connected to one end of the resistor RG19 and one end of the resistor RG55; the output end of the comparator M1 is connected to the second pin of the PIC16F72 microcontroller; One end of the resistor RG23 is connected to the output end of the comparator M1 , the other end of the resistor RG23 is connected to the other end of the resistor RG15 and the other end of the resistor RG19 , and the other end of the resistor RG55 is grounded.

2. The brushless motor controller for an electric vehicle as claimed in claim 1, characterized in that; The power supply module includes a three-terminal voltage regulator LM317, a three-terminal voltage regulator L78L05 and a capacitor C20, the three-terminal voltage regulator LM317 outputs a constant +13.5V voltage, the three-terminal voltage regulator L78L05 inputs a constant +13.5V voltage and outputs a constant +5V voltage; The input end of the three-terminal voltage regulator LM317 is connected to one end of the resistor R1, one end of the resistor R80 and the positive end of the capacitor C4, the negative end of the capacitor C4 is connected to one end of the resistor R2, the other end of the resistor R2 is connected to one end of the resistor R36, the other end of the resistor R36 is connected to the other end of the resistor R80 and the output end of the three-terminal voltage regulator LM317; The input end of the three-terminal voltage regulator L78L05 is connected to one end of the capacitor C18, one end of the resistor R75 and one end of the resistor R77, the other end of the capacitor C18 is connected to one end of the capacitor C20, and the output end of the three-terminal voltage regulator L78L05 is connected to the other end of the resistor R75, the other end of the resistor R77 and the other end of the capacitor C20; The output end of the three-terminal voltage regulator L78L05 and the output end of the three-terminal voltage regulator LM317 are both connected to the 20th pin of the PIC16F72 microcontroller, both ends of the resistor R2 and one end of the capacitor C18 are grounded, and the output end of the three-terminal voltage regulator LM317 is connected to the input end of the three-terminal voltage regulator L78L05.

3. The brushless motor controller for an electric vehicle as claimed in claim 1, characterized in that; The overcurrent protection module includes a comparator M2, wherein the negative input end of the comparator M2 is connected to one end of the resistor RG22, the positive input end is connected to one end of the resistor RG29 and one end of the resistor RG30, and the output end is connected to the 21st pin of the PIC16F72 single-chip computer; The other end of the resistor RG22 is connected to one end of the resistor RG27 and one end of the resistor RG25. The other ends of the resistor RG27, RG25 and RG29 are grounded. The other end of the resistor RG30 is connected to the output end of the comparator M2.

4. The electric vehicle brushless motor controller according to claim 1, characterized in that; The brake module includes a terminal P3 and a terminal P4, wherein the first pin of the terminal P3 is connected to one end of a resistor RG28, the second pin is grounded, the other end of the resistor RG28 is connected to one end of a resistor RG32 and one end of a capacitor CK8, and the other end of the capacitor CK8 is connected to one end of a resistor RG34; The first pin of the terminal P4 is connected to the cathode of the diode DI4 and one end of the capacitor CK11, the anode of the diode DI4 is connected to the fifth pin of the PIC16F72 microcontroller, and the third pin of the terminal P4 is connected to the other end of the resistor RG32 and the other end of the resistor RG34; The second pin of P4, the other end of the capacitor CK8 and the other end of the capacitor CK11 are grounded.

5. The brushless motor controller for an electric vehicle as claimed in claim 1, characterized in that; The functional module includes a terminal P6 and a terminal P7, wherein the first pin of the terminal P6 is grounded, the second pin of the terminal P6 is connected to one end of a resistor RG53, the other end of the resistor RG53 is connected to one end of a resistor RG48, the other end of the resistor RG48 is connected to one end of a resistor RG46, one end of a capacitor CK13 and a positive electrode of a diode DI6, the negative electrode of the diode DI6 is connected to one end of a resistor RG49 and one end of a resistor RG50, the other end of the resistor RG49 is connected to the third pin of the terminal P7 and the sixth pin of a PIC16F72 single-chip computer, the second pin of the terminal P7 is connected to the eleventh pin of the PIC16F72 single-chip computer, and the other end of the resistor RG50 is connected to the first pin of the terminal P7 and the twelfth pin of the PIC16F72 single-chip computer; The other end of the capacitor CK13 and the other end of the resistor RG46 are grounded.

6. The brushless motor controller for an electric vehicle as claimed in claim 1, characterized in that; The sensing module includes a terminal P8 and a diode DI9, the first pin of the P8 is connected to one end of a resistor RG69 and one end of a resistor RG75, and the other end of the resistor RG69 is connected to one end of a capacitor CK18; The second pin of the terminal P8 is connected to one end of a resistor RG71 and one end of a resistor RG74, and the other end of the resistor RG71 is connected to one end of a capacitor CP16; The third pin of the terminal P8 is connected to one end of a resistor RG72 and one end of a resistor RG73, and the other end of the resistor RG72 is connected to one end of a capacitor CP15; The fifth pin of the terminal P8, the other end of the capacitor CK18, the other end of the capacitor CP16 and the other end of the capacitor CP15 are all grounded; The other end of the resistor RG69 is also connected to the 15th pin of the PIC16F72 single-chip microcomputer, the other end of the resistor RG71 is also connected to the 17th pin of the PIC16F72 single-chip microcomputer, and the other end of the resistor RG72 is also connected to the 16th pin of the PIC16F72 single-chip microcomputer; The other end of the resistor RG73 , the other end of the resistor RG74 , and the other end of the resistor RG75 are all connected to the anode of the diode DI9 .

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