Simple and practical low-power frequency converter circuit

Abstract

The utility model discloses a simple and practical low-power frequency converter circuit, which comprises a switching power supply, a rectification filter circuit, a brake bleeder circuit, a three-phase inverter circuit, a main controller circuit and a protection circuit, according to the embodiment, a DSP control technology, a high-frequency switching power supply technology and a power device integration technology are combined, and a low-power frequency converter circuit which is all-directionally protected, light and practical is designed. Firstly, a high-frequency switching power supply is used for providing a low-voltage direct-current power supply, so that the size and weight of the circuit are reduced; secondly, high-frequency clutters of the circuit are filtered by using a large capacitor, comprehensive protection of overvoltage, over-temperature and overcurrent is realized by using an intelligent power module, and the anti-interference capability and the safety of the circuit are improved; and thirdly, the circuit utilizes a DSP (Digital Signal Processor) controller to conveniently realize the algorithm control of the motor and realize the variable-frequency variable-voltage energy-saving control of the motor. In a word, the circuit is light in structure, safe, stable, energy-saving, consumption-reducing, comprehensive in function, suitable for the fields of elevators, textiles, numerical control and the like, high in cost performance and high in practicability.

Description

TECHNICAL FIELD

[0001] The utility model belongs to motor frequency conversion technical field, specifically relates to a simple and practical low power frequency converter circuit containing switching power supply, main circuit, control circuit and protection current. BACKGROUND

[0002] The frequency converter is a kind of device that converts fixed frequency AC into frequency and voltage continuously adjustable AC to drive motor to run by using frequency conversion technology and microelectronic technology.The basic principle is to realize the conversion of power supply by main controller, convert AC into DC, and then convert DC into AC with variable frequency and voltage.Thus, by adjusting the frequency and voltage of power supply, the accurate control of motor speed, torque and power can be realized.The frequency converter is widely used in numerical control, elevator and new energy fields.At present, the design of many low power frequency converters is mostly based on DSP main control chip and intelligent power module IPM module, which has many advantages such as energy saving and consumption reduction, comprehensive function, small size, affordable price, simple design and strong anti-interference capability. SUMMARY

[0003] Based on the mature development of DSP control technology, high-frequency switching power supply technology and power device integration technology, the simple and practical low power frequency converter circuit fully applies the advantages of switching power supply chip TOP227, main controller TMS320LF2406 and intelligent power module IPM, and designs a small frequency converter with comprehensive performance.Firstly, a low-voltage DC power supply is designed by using switching power supply technology, secondly, a rectifier filter circuit is designed by using rectifier bridge and large capacitor, thirdly, a braking discharge circuit is designed by using MOS tube and high-power resistor, fourthly, an anti-interference inverter bridge is designed by using intelligent power module IPM, fifthly, motor control algorithm is realized by using main controller DSP chip TMS320LF2406 to generate six-way SVPWM pulse, realizing frequency and voltage variable energy-saving control of motor, and sixthly, the frequency converter is designed with overvoltage, overtemperature and overcurrent protection circuit, and the frequency converter can send blocking signal to block IPM module and system circuit in time if circuit fault occurs.Therefore, the frequency converter comprehensively applies various advanced technologies, has comprehensive function, high cost performance and is safe and reliable.

[0004] A simple and practical low power frequency converter circuit, comprising: switching power supply, rectifier filter circuit, braking discharge circuit, three-phase inverter circuit, main controller circuit and protection circuit.

[0005] The switching power supply is connected with rectifier filter circuit, braking discharge circuit, three-phase inverter circuit, main controller circuit and protection circuit, and is used to generate DC low-voltage power supply required by system.

[0006] The rectifier and filter circuit is connected to the switching power supply, brake discharge circuit, three-phase inverter circuit and protection circuit, and is used to convert the input 220V AC power into DC power.

[0007] The aforementioned brake discharge circuit is connected to the switching power supply, rectifier filter circuit, three-phase inverter circuit and main controller circuit. It is used to open the circuit when the motor brakes to allow the braking resistor to consume feedback energy, suppress the rise of bus voltage, and protect the components.

[0008] The three-phase inverter circuit is connected to the switching power supply, rectifier filter circuit, brake discharge circuit, main controller circuit and protection circuit. It is used to invert DC voltage into a variable frequency and variable voltage three-phase AC voltage to drive the motor to operate in energy-saving variable frequency mode.

[0009] The main controller circuit is connected to the switching power supply, brake discharge circuit, three-phase inverter circuit and protection circuit. It is used to receive external signals and then output the control signals required for motor operation through the control algorithm to control the motor to run as needed.

[0010] The protection circuit is connected to the switching power supply, rectifier filter circuit, three-phase inverter circuit and main controller circuit. It is used to sample the voltage and current signals of the inverter bridge and feed them back to the main controller.

[0011] The switch power supply contains resistance R1~R15, capacitor C1~C20, inductance L1~L3, diode D1~D8, Schottky diode Z1, transformer TR1, photoelectric coupling OC1, switch power supply chip U1, voltage stabilizing source chip U2, U3, filter LCL, light emitting diode D9; wherein: the negative pole of capacitor C1, C3, C6, C8~C11, C13, C17, the positive pole of capacitor C15 and C16, one end of capacitor C2, C4, C12, C14, C18, the 2nd pin of switch power supply chip U1, the 1st pin of switch power supply chip U2, the 2nd pin of filter LCL, one end of resistance R10~R12, the 5th pin of voltage stabilizing source chip U3 and the 4th, 7th pin of transformer TR1 are connected with ground terminal, the negative pole of capacitor C19, one end of capacitor C20 and the 10th pin of transformer TR1 are connected with isolated ground terminal, one end of resistance R1 and the positive pole of capacitor C1 are connected with signal DRIVE, the other end of resistance R1 is connected with the negative pole of diode D2, the positive pole of diode D2 and D3 is connected with the 3rd pin of transformer TR1, the negative pole of diode D3 is connected with one end of resistance R2, the other end of resistance R2 is connected with the other end of capacitor C2, the positive pole of capacitor C3 and the 4th pin of photoelectric coupling OC1, the other end of capacitor C4 is connected with the positive pole of Schottky diode Z1, one end of resistance R3 and capacitor C5 and the 1st pin of transformer TR1 are connected with PV, the negative pole of Schottky diode Z1 is connected with resistance R3 and the other end of capacitor C5 and the negative pole of diode D1, the positive pole of diode D1 is connected with the 3rd pin of switch power supply chip U1 and the 2nd pin of transformer TR1, the 1st pin of switch power supply chip U1 is connected with one end of resistance R4 and the 3rd pin of photoelectric coupling OC1, the other end of resistance R4 is connected with the positive pole of capacitor C6, the 1st pin of photoelectric coupling OC1 is connected with one end of resistance R5 and R6, the other end of resistance R5 is connected with signal PO+, the other end of resistance R6 is connected with the 1st pin of voltage stabilizing source chip U3, the 2nd pin of photoelectric coupling OC1 is connected with one end of resistance R7, the other end of resistance R7 is connected with one end of capacitor C7, one end of resistance R8, R9 is connected with signal +5V, +15V respectively, the other end of capacitor C7 is connected with the other end of resistance R8~R10 and the 8th pin of voltage stabilizing source chip U3, the positive pole of diode D4~D7 is connected with the 5th, 6th, 8th, 9th pin of transformer TR1 respectively, the negative pole of diode D4 is connected with one end of inductance L1 and the positive pole of capacitor C8 with signal PO+, the other end of inductance L1 is connected with the positive pole of capacitor C9 with signal +15V, the negative pole of diode D5 is connected with one end of inductance L2 and the positive pole of capacitor C10, the other end of inductance L2 is connected with the positive pole of capacitor C11, the other end of capacitor C12, the 3rd pin of voltage stabilizing source chip U2 with signal +5V, the 2nd pin of voltage stabilizing source chip U2 is connected with the positive pole of capacitor C13, the other end of capacitor C14 and the 1st pin of filter LCL, the 3rd pin of filter LCL is connected with the positive pole of light emitting diode D9 with +3.3V, the negative pole of the light emitting diode D9 is connected with the other end of the resistor R11, the negative pole of the diode D8 is connected with the positive pole of the diode D6, the positive pole of the diode D8, the negative pole of the capacitor C15 and one end of the inductor L3 are connected, the other end of the inductor L3 and the negative pole of the capacitor C16 are connected with the signal -15V, the negative pole of the diode D6 is connected with one end of the resistor R13, the other end of the resistor R13, the positive pole of the capacitor C17 and one end of the resistor R14 are connected, the other ends of the resistors R12, R14 and the other end of the capacitor C18 are connected with the signal CVD, the negative pole of the diode D7 is connected with the positive pole of the capacitor C19, the capacitor C20 and the other end of the resistor R15 with the signal +24V.

[0012] The rectifier filter circuit comprises a fuse FU1, a voltage-dependent resistor R16-R18, a resistor R19, a capacitor C21-C24, a filter L1, a rectifier bridge B1, a relay RL1 and a diode D10; wherein: one end of the fuse FU1 is connected with one end of the AC 220 power supply, the voltage-dependent resistor R16 and R18 and one end of the capacitor C22 are connected with the other end of the AC 220 power supply, the other end of the fuse FU1 and the voltage-dependent resistor R16 is connected with the voltage-dependent resistor R17, one end of the capacitor C21 and the first pin of the filter L1, the voltage-dependent resistor R17 and R18 and the other end of the capacitor C21 and C22 are connected with the second pin of the filter L1, the third and fourth pins of the filter L1 are respectively connected with both ends of the capacitor C23 and the first and third pins of the rectifier bridge B1, the third pin of the rectifier bridge B1 is connected with the strong electricity ground, the second pin of the rectifier bridge B1 is connected with the positive pole of the capacitor C24 and the second pin of the relay RL1 with the signal PV, the fourth pin of the rectifier bridge B1 is connected with one end of the resistor R19, the other end of the resistor R19 and the negative pole of the capacitor C24 are connected with the signal -PV, the third pin of the relay RL1 is suspended, the first pin of the relay RL1 is connected with the signal PG, the fifth pin of the relay RL1 is connected with the negative pole of the diode D10 with the signal +5V, the fourth pin of the relay RL1 is connected with the positive pole of the diode D10 with the ground.

[0013] The brake discharge circuit comprises resistors R20-R24, capacitors C25-C26, diode D11, optical coupler OC2, MOS tube Q2; wherein: one end of resistor R20 is connected to signal PWMBrake, the other end of resistor R20 is connected to capacitor C25, one end of resistor R21 and the third pin of optical coupler OC2, the other end of capacitor C25 and resistor R21 is connected to the second pin of optical coupler OC2 and signal +5V, the sixth and seventh pins of optical coupler OC2 are connected to one end of resistor R22, the other end of resistor R22 is connected to resistor R23, one end of capacitor C26 and the gate G of MOS tube Q2, the source S of MOS tube Q2 is connected to signal -PV, the drain D of MOS tube Q2 is connected to one end of resistor R24 and the positive electrode of diode D11, the other end of resistor R24 and the negative electrode of diode D11 is connected to signal PV, the other end of resistor R23 and capacitor C26 is connected to the fifth pin of optical coupler OC2 and ground, the eighth pin of optical coupler OC2 is connected to DRIVER signal.

[0014] The three-phase inverter circuit comprises resistors R26-R30, capacitors C30-C42, diodes D12-D14, IPM module U6, Hall sensors U4-U5, and asynchronous motor M; wherein: one end of capacitor C30 is connected to the anodes of diodes D12-D14, one end of capacitor C34, and the 14th pin of IPM module U6 to signal DRIVE; the other ends of capacitors C30 and C34 are connected to one end of capacitors C31-C33 to the ground end; the other ends of capacitors C31-C33 are respectively connected to the 2nd, 6th, and 10th pins of IPM module U6; the cathodes of diodes D12-D14 are respectively connected to one end of resistors R26-R28; the other end of resistor R26 is connected to the anode of capacitor C35, one end of capacitor C36, and the 3rd pin of IPM module U6; the cathode of capacitor C35 is connected to the other end of capacitor C36 and the 4th pin of IPM module U6; the other end of resistor R27 is connected to the anode of capacitor C37, one end of capacitor C38, and the 7th pin of IPM module U6; the cathode of capacitor C37 is connected to the other end of capacitor C38 and the 8th pin of IPM module U6; the other end of resistor R28 is connected to the anode of capacitor C39, one end of capacitor C40, and the 12th pin of IPM module U6; the cathode of capacitor C39 is connected to the other end of capacitor C40 and the 13th pin of IPM module U6; the 1st, 5th, 9th, 19th, 20th, 21st, 18th, 22nd, and 11th pins of IPM module U6 are respectively connected to signals PWMU+, PWMV+, PWMW+, PWMU-, PWMV-, PWMW-, FO signal, PG signal, and strong electric ground signal; the 23rd-25th pins of IPM module U6 are respectively connected to the U, V, and W pins of asynchronous motor M; the 6th pins of Hall sensors U4 and U5 are respectively connected to the U and V pins of asynchronous motor M; the 1st pins of Hall sensors U4 and U5 are connected to signal -15V; the 3rd pins of Hall sensors U4 and U5 are connected to signal +15V; the 2nd pins of Hall sensors U4 and U5 are connected to the ground end; the 4th pins of Hall sensors U4 and U5 are respectively connected to signals IUsensor and IVsensor; the 26th pin of IPM module U6 is connected to one end of resistors R29 and R30 to signal PIsensor; the 16th pin of IPM module U6 is connected to the other end of resistor R29 and one end of capacitor C41; one end of capacitor C42 is connected to the 17th pin of IPM module U6; the other ends of capacitors C41 and C42 are connected to the other end of resistor R30 to the ground end.

[0015] The main controller circuit includes resistors R35-R41, capacitors C45-C52, a light emitting diode D15, a crystal oscillator XTAL1, a DSP chip U7, a reset chip U8, and a memory chip U9; wherein: the 40th pin of the DSP chip U7 is connected to +5V, the 20th, 35th, 59th, 91st, 4th, 30th, 47th, 54th, 64th, 98th pins of the DSP chip U7 and the 3rd pin of the reset chip U8 are connected to +3.3V, the 84th, 19th, 34th, 58th, 90th, 3rd, 29th, 46th, 53rd, 63rd, 97th pins of the DSP chip U7 are connected to ground, the 39th, 37th, 36th, 33rd, 31st, 28th, 12th, 13th, 6th, 51st, 23rd, 24th, 1st, 67th, 69th, 70th, 77th, 79th pins of the DSP chip U7 are connected to signals PWMU+, PWMV+, PWMW+, PWMU-, PWMV-, PWMW-, IOPB4, IOPB5, FO, short, DRIVE, PWMBrake, TRST, CVD, CCD, AGND, IA, IB respectively, the 1st pin of the reset chip U8 is connected to the negative electrode of the light emitting diode D15, one end of the capacitor C45, one end of the capacitors C49-C51, the negative electrode of the capacitor C52, and the 1st-4th, 7th pins of the memory chip U9, which are connected to ground, the 93rd pin of the DSP chip U7 is connected to signal RST with one end of the resistor R35 and the other end of the capacitor C45, the other end of the resistor R35 is connected to the 2nd pin of the reset chip U8, one end of the capacitors C46-C48 is connected to the 8th pin of the DSP chip U7, the other end of the capacitors C46, C47 is connected to the 9th pin of the DSP chip U7 and one end of the resistor R36, the other end of the resistor R36 is connected to the other end of the capacitor C48, one end of the resistor R37 is connected to signal XF with the 86th pin of the DSP chip U7, the other end of the resistor R37 is connected to the positive electrode of the light emitting diode D15, the other end of the capacitor C51 and the positive electrode of the capacitor C52 are connected to +3.3V with the 10th pin of the DSP chip U7, one end of the resistor R38 is connected to the 88th pin of the DSP chip U7, the other end of the resistor R38 is connected to one end of the resistor R39, one end of the crystal oscillator XTAL1, and the other end of the capacitor C49, the other end of the resistor R39 is connected to the other end of the crystal oscillator XTAL1, the 87th pin of the DSP chip U7, and the other end of the capacitor C50, the 8th pin of the memory chip U9 is connected to +3.3V with one end of the resistors R40, R41, the other ends of the resistors R40, R41 are connected to signals IOPB4, IOPB5 with the 6th, 5th pins of the memory chip U9 respectively.

[0016] The protection circuit comprises resistors R45-R50, capacitors C55-C62, a voltage stabilizing tube Z2 and an operational amplifier chip U10, wherein one end of the capacitors C55-C62, one end of the resistor R48 and a positive electrode of the voltage stabilizing tube Z2 are connected to a ground terminal, one end of the resistor R45 and the other end of the capacitor C55 are connected to a signal IUsensor, one end of the resistor R46 and the other end of the capacitor C56 are connected to a signal IVsensor, one end of the resistor R47 is connected to a signal PG, the other end of the resistor R47, the other end of the capacitor C59, a negative electrode of the voltage stabilizing tube Z2, the other end of the resistor R48 and one end of the resistor R49 are connected to a signal PVsensor, one end of the resistor R50 and the other end of the capacitor C60 are connected to a signal PIsensor, the other ends of the resistors R45, R46, R49 and R50 are connected to the 10th, 12th, 3rd and 5th pins of the operational amplifier chip U10 respectively, the 8th and 9th pins of the operational amplifier chip U10 are connected to the other end of the capacitor C57 and a signal IA, the 13th and 14th pins of the operational amplifier chip U10 are connected to the other end of the capacitor C58 and a signal IB, the 4th and 11th pins of the operational amplifier chip U10 are connected to one end of the capacitors C63 and C64 respectively, the other ends of the capacitors C63 and C64 are connected to a signal AGND, the 1st and 2nd pins of the operational amplifier chip U10 are connected to the other end of the capacitor C61 and a signal CVD, and the 6th and 7th pins of the operational amplifier chip U10 are connected to the other end of the capacitor C62 and a signal CCD.

[0017] The simple and practical low-power frequency converter circuit fully applies the characteristics of the high-frequency switching power supply, the powerful control function of the main controller DSP chip TMS320LF2406, and the strong anti-interference ability and comprehensive protection function of the intelligent power module IPM, high-frequency switching power supplies are designed, low-voltage direct-current power supplies required by the system are provided, a rectifier filter circuit, a braking discharge circuit and a three-phase inverter circuit are designed, voltage AC / DC / AC conversion is realized, a main controller circuit and a safety protection circuit are designed, frequency and voltage control of the motor and overvoltage, overcurrent and overtemperature signal sampling are realized, and a blocking signal can be sent in time to protect the IPM module and the system circuit. BRIEF DESCRIPTION OF DRAWINGS

[0018] Figure 1 It is a structural schematic view of the utility model.

[0019] Figure 2 It is a switching power supply diagram.

[0020] Figure 3 It is a rectifier filter circuit diagram.

[0021] Figure 4 It is a braking discharge circuit diagram.

[0022] Figure 5 is a three-phase inverter circuit diagram.

[0023] Figure 6 is a main controller circuit diagram.

[0024] Figure 7 is a protection circuit diagram. DETAILED DESCRIPTION

[0025] In order to more specifically describe the utility model, the technical scheme of the utility model is described in detail below in combination with the drawings and specific embodiments.

[0026] As Figure 1 shown, a simple and practical small power frequency converter circuit, comprising: switching power supply, rectifier filter circuit, brake discharge circuit, three-phase inverter circuit, main controller circuit and protection circuit.

[0027] The switch power supply is connected with rectifier filter circuit, brake discharge circuit, three-phase inverter circuit, main controller circuit and protection circuit, which is used for generating DC low voltage power supply required by the system; in the embodiment, the switch power supply contains resistors R1-R15, capacitors C1-C20, inductors L1-L3, diodes D1-D8, Schottky diode Z1, transformer TR1, optocoupler OC1, switch power supply chip U1, voltage stabilizer chips U2 and U3, filter LCL and light emitting diode D9; wherein: the negative poles of capacitors C1, C3, C6, C8-C11, C13 and C17, the positive pole of capacitors C15 and C16, one end of capacitors C2, C4, C12, C14 and C18, the second pin of switch power supply chip U1, the first pin of switch power supply chip U2, the second pin of filter LCL, one end of resistors R10-R12, the fifth pin of voltage stabilizer chip U3 and the fourth and seventh pins of transformer TR1 are connected with ground terminal, the negative pole of capacitor C19, one end of capacitor C20 and the tenth pin of transformer TR1 are connected with isolated ground terminal, one end of resistor R1 and the positive pole of capacitor C1 are connected with signal DRIVE, the other end of resistor R1 and the negative pole of diode D2 are connected, the positive poles of diodes D2 and D3 are connected with the third pin of transformer TR1, the negative pole of diode D3 is connected with one end of resistor R2, the other end of resistor R2 is connected with the other end of capacitor C2, the positive pole of capacitor C3 and the fourth pin of optocoupler OC1, the other end of capacitor C4 is connected with the positive pole of Schottky diode Z1, one end of resistor R3 and capacitor C5 and the first pin of transformer TR1 are connected with PV, the negative pole of Schottky diode Z1 is connected with the other end of resistor R3 and capacitor C5 and the negative pole of diode D1, the positive pole of diode D1 is connected with the third pin of switch power supply chip U1 and the second pin of transformer TR1, the first pin of switch power supply chip U1 is connected with one end of resistor R4 and the third pin of optocoupler OC1, the other end of resistor R4 is connected with the positive pole of capacitor C6, the first pin of optocoupler OC1 is connected with one end of resistors R5 and R6, the other end of resistor R5 is connected with signal PO+, the other end of resistor R6 is connected with the first pin of voltage stabilizer chip U3, the second pin of optocoupler OC1 is connected with one end of resistor R7, the other end of resistor R7 is connected with one end of capacitor C7, one end of resistors R8 and R9 is connected with signals +5V and +15V respectively, the other end of capacitor C7 is connected with the other ends of resistors R8-R10 and the eighth pin of voltage stabilizer chip U3, the positive poles of diodes D4-D7 are connected with the fifth, sixth, eighth and ninth pins of transformer TR1 respectively, the negative pole of diode D4 is connected with one end of inductor L1 and the positive pole of capacitor C8, the other end of inductor L1 is connected with the positive pole of capacitor C9, the negative pole of diode D5 is connected with one end of inductor L2 and the positive pole of capacitor C10, the other end of inductor L2 is connected with the positive pole of capacitor C11, the other end of capacitor C12 and the third pin of voltage stabilizer chip U2, which are connected with signal +5V.The second pin of the voltage stabilizer chip U2 is connected with the positive pole of the capacitor C13, the other end of the capacitor C14 and the first pin of the filter LCL, the third pin of the filter LCL is connected with the positive pole of the light emitting diode D9 to +3.3V, the negative pole of the light emitting diode D9 is connected with the other end of the resistor R11, the negative pole of the diode D8 is connected with the positive pole of the diode D6, the positive pole of the diode D8, the negative pole of the capacitor C15 and one end of the inductor L3 are connected, the other end of the inductor L3 and the negative pole of the capacitor C16 are connected to signal -15V, the negative pole of the diode D6 is connected with one end of the resistor R13, the other end of the resistor R13, the positive pole of the capacitor C17 and one end of the resistor R14 are connected, the other ends of the resistors R12, R14 and the other end of the capacitor C18 are connected to signal CVD, the negative pole of the diode D7 is connected with the positive pole of the capacitor C19, the capacitor C20 and the other end of the resistor R15 to signal +24V. The switch power supply converts the system required DC low voltage power supply by applying high frequency switch power supply chip.

[0028] The rectifier filter circuit is connected with the switch power supply, the brake discharge circuit, the three-phase inverter circuit and the protection circuit, and is used for converting the input 220V alternating current into direct current; in the embodiment, the rectifier filter circuit comprises a fuse FU1, voltage-dependent resistors R16-R18, a resistor R19, capacitors C21-C24, a filter L1, a rectifier bridge B1, a relay RL1 and a diode D10; wherein: one end of the fuse FU1 is connected with one end of an AC 220 alternating current power supply, the voltage-dependent resistors R16 and R18 and one end of the capacitor C22 are connected with the other end of the AC 220 alternating current power supply, the other end of the fuse FU1 and the voltage-dependent resistor R16 is connected with the voltage-dependent resistor R17, one end of the capacitor C21 and the first pin of the filter L1, the voltage-dependent resistors R17 and R18 and the other ends of the capacitors C21 and C22 are connected with the second pin of the filter L1, the third and fourth pins of the filter L1 are respectively connected with two ends of the capacitor C23 and the first and third pins of the rectifier bridge B1, the third pin of the rectifier bridge B1 is connected with a strong current grounding end, the second pin of the rectifier bridge B1 is connected with the positive pole of the capacitor C24 and the second pin of the relay RL1 to signal PV, the fourth pin of the rectifier bridge B1 is connected with one end of the resistor R19, the other end of the resistor R19 and the negative pole of the capacitor C24 are connected with signal -PV, the third pin of the relay RL1 is suspended, the first pin of the relay RL1 is connected with signal PG, the fifth pin of the relay RL1 is connected with the negative pole of the diode D10 to signal +5V, and the fourth pin of the relay RL1 is connected with the positive pole of the diode D10 to a grounding end. The rectifier filter circuit is used for converting the input 220V alternating current into direct current.

[0029] The brake discharge circuit is connected with the switching power supply, the rectification filter circuit, the three-phase inverter circuit and the main controller circuit, and is used for opening the circuit to let the brake resistor consume the feedback energy when the motor brakes, so as to suppress the rise of the bus voltage and protect the components; in the embodiment, the brake discharge circuit comprises resistors R20-R24, capacitors C25-C26, a diode D11, an optical coupler OC2 and a MOS tube Q2; wherein: one end of the resistor R20 is connected with a signal PWMBrake, the other end of the resistor R20 is connected with the capacitor C25, one end of the resistor R21 and the third pin of the optical coupler OC2, the other end of the capacitor C25 and the resistor R21 is connected with the second pin of the optical coupler OC2 and a signal +5V, the sixth and seventh pins of the optical coupler OC2 are connected with one end of the resistor R22, the other end of the resistor R22 is connected with the resistor R23, one end of the capacitor C26 and the gate electrode G of the MOS tube Q2, the source electrode S of the MOS tube Q2 is connected with a signal -PV, the drain electrode D of the MOS tube Q2 is connected with one end of the resistor R24 and the positive electrode of the diode D11, the other end of the resistor R24 and the negative electrode of the diode D11 is connected with a signal PV, the other end of the resistor R23 and the capacitor C26 is connected with the fifth pin of the optical coupler OC2 and a ground terminal, and the eighth pin of the optical coupler OC2 is connected with a DRIVER signal. The brake discharge circuit is used for opening the circuit to let the brake resistor consume the feedback energy when the motor brakes, so as to suppress the rise of the bus voltage and protect the components.

[0030] The three-phase inverter circuit is connected with the switching power supply, the rectification filter circuit, the brake discharge circuit, the main controller circuit and the protection circuit, and is used for inverting the direct current voltage into variable frequency variable voltage three-phase alternating current voltage to drive the motor to run in energy-saving variable frequency mode. In the embodiment, the three-phase inverter circuit comprises resistors R26-R30, capacitors C30-C42, diodes D12-D14, an IPM module U6, Hall sensors U4-U5 and an asynchronous motor M. One end of the capacitor C30 is connected with the positive poles of the diodes D12-D14, one end of the capacitor C34 and the 14th pin of the IPM module U6 to the signal DRIVE, the other ends of the capacitors C30 and C34 are connected with one end of the capacitors C31-C33 to the ground end, the other ends of the capacitors C31-C33 are respectively connected with the 2nd, 6th and 10th pins of the IPM module U6, the negative poles of the diodes D12-D14 are respectively connected with one end of the resistors R26-R28, the other end of the resistor R26 is connected with the positive pole of the capacitor C35, one end of the capacitor C36 and the 3rd pin of the IPM module U6, the negative pole of the capacitor C35 is connected with the other end of the capacitor C36 and the 4th pin of the IPM module U6, the other end of the resistor R27 is connected with the positive pole of the capacitor C37, one end of the capacitor C38 and the 7th pin of the IPM module U6, the negative pole of the capacitor C37 is connected with the other end of the capacitor C38 and the 8th pin of the IPM module U6, the other end of the resistor R28 is connected with the positive pole of the capacitor C39, one end of the capacitor C40 and the 12th pin of the IPM module U6, the negative pole of the capacitor C39 is connected with the other end of the capacitor C40 and the 13th pin of the IPM module U6, the 1st, 5th, 9th, 19th, 20th, 21st, 18th, 22nd and 11th pins of the IPM module U6 are respectively connected with the signals PWMU+, PWMV+, PWMW+, PWMU-, PWMV-, PWMW-, the FO signal, the PG signal and the strong electric ground signal, the 23rd-25th pins of the IPM module U6 are respectively connected with the U, V and W pins of the asynchronous motor M, the 6th pins of the Hall sensors U4 and U5 are respectively connected with the U and V pins of the asynchronous motor M, the 1st pins of the Hall sensors U4 and U5 are connected with the signal -15V, the 3rd pins of the Hall sensors U4 and U5 are connected with the signal +15V, the 2nd pins of the Hall sensors U4 and U5 are connected with the ground end, the 4th pins of the Hall sensors U4 and U5 are respectively connected with the signals IUsensor and IVsensor, the 26th pin of the IPM module U6 is connected with one end of the resistors R29 and R30 to the signal PIsensor, the 16th pin of the IPM module U6 is connected with the other end of the resistor R29 and one end of the capacitor C41, one end of the capacitor C42 is connected with the 17th pin of the IPM module U6, the other ends of the capacitors C41 and C42 are connected with the other end of the resistor R30 to the ground end. The three-phase inverter circuit is used for inverting the direct current voltage into variable frequency variable voltage three-phase alternating current voltage to drive the motor to run in energy-saving variable frequency mode.

[0031] The main controller circuit is connected with the switching power supply, the brake discharge circuit, the three-phase inverter circuit and the protection circuit, and is used for accepting external signals and outputting control signals required by motor operation through a control algorithm to control the motor to operate as required. In the embodiment, the main controller circuit comprises resistors R35-R41, capacitors C45-C52, a light emitting diode D15, a crystal oscillator XTAL1, a DSP chip U7, a reset chip U8 and a memory chip U9. The 40th pin of the DSP chip U7 is connected with +5V, the 20th, 35th, 59th, 91st, 4th, 30th, 47th, 54th, 64th, 98th pin of the DSP chip U7 and the 3rd pin of the reset chip U8 are connected with +3.3V, the 84th, 19th, 34th, 58th, 90th, 3rd, 29th, 46th, 53rd, 63rd, 97th pin of the DSP chip U7 are connected with the ground terminal, the 39th, 37th, 36th, 33rd, 31st, 28th, 12th, 13th, 6th, 51st, 23rd, 24th, 1st, 67th, 69th, 70th, 77th, 79th pin of the DSP chip U7 are respectively connected with signals PWMU+, PWMV+, PWMW+, PWMU-, PWMV-, PWMW-, IOPB4, IOPB5, FO, short, DRIVE, PWMBrake, TRST, CVD, CCD, AGND, IA, IB, the 1st pin of the reset chip U8 is connected with the negative electrode of the light emitting diode D15, one end of the capacitor C45, one end of the capacitors C49-C51, the negative electrode of the capacitor C52 and the ground terminal of the 1st-4th, 7th pin of the memory chip U9, the 93rd pin of the DSP chip U7 is connected with one end of the resistor R35 and the other end of the capacitor C45 to signal RST, the other end of the resistor R35 is connected with the 2nd pin of the reset chip U8, one end of the capacitors C46-C48 is connected with the 8th pin of the DSP chip U7, the other end of the capacitors C46, C47 is connected with the 9th pin of the DSP chip U7 and one end of the resistor R36, the other end of the resistor R36 is connected with the other end of the capacitor C48, one end of the resistor R37 is connected with the 86th pin of the DSP chip U7 to signal XF, the other end of the resistor R37 is connected with the positive electrode of the light emitting diode D15, the other end of the capacitor C51 and the positive electrode of the capacitor C52 are connected with the 10th pin of the DSP chip U7 to +3.3V, one end of the resistor R38 is connected with the 88th pin of the DSP chip U7, the other end of the resistor R38 is connected with one end of the resistor R39, one end of the crystal oscillator XTAL1 and the other end of the capacitor C49, the other end of the resistor R39 is connected with the other end of the crystal oscillator XTAL1, the 87th pin of the DSP chip U7 and the other end of the capacitor C50, the 8th pin of the memory chip U9 is connected with one end of the resistors R40, R41 to +3.3V, the other end of the resistors R40, R41 is respectively connected with the 6th, 5th pin of the memory chip U9 to signals IOPB4, IOPB5. The main controller circuit is used for sampling external signals, outputting control signals required by motor operation through a control algorithm and controlling the motor to operate as required.

[0032] The protection circuit is connected with the switching power supply, the rectification filter circuit, the three-phase inverter circuit and the main controller circuit, which is used for sampling the voltage and current signals of the inverter bridge and feeding back to the main controller; in the embodiment, the protection circuit comprises resistors R45-R50, capacitors C55-C62, a voltage stabilizing tube Z2 and an operational amplifier chip U10; one end of the capacitors C55-C62 is connected with one end of the resistor R48 and the positive electrode of the voltage stabilizing tube Z2 to the ground terminal, one end of the resistor R45 is connected with the other end of the capacitor C55 to the signal IUsensor, one end of the resistor R46 is connected with the other end of the capacitor C56 to the signal IVsensor, one end of the resistor R47 is connected with the signal PG, the other end of the resistor R47 is connected with the other end of the capacitor C59, the negative electrode of the voltage stabilizing tube Z2, the other end of the resistor R48 and one end of the resistor R49 to the signal PVsensor, one end of the resistor R50 is connected with the other end of the capacitor C60 to the signal PIsensor, the other ends of the resistors R45, R46, R49 and R50 are respectively connected with the 10th, 12th, 3rd and 5th pins of the operational amplifier chip U10, the 8th and 9th pins of the operational amplifier chip U10 are connected with the other end of the capacitor C57 to the signal IA, the 13th and 14th pins of the operational amplifier chip U10 are connected with the other end of the capacitor C58 to the signal IB, the 4th and 11th pins of the operational amplifier chip U10 are respectively connected with one end of the capacitors C63 and C64, the other ends of the capacitors C63 and C64 are connected to the signal AGND, the 1st and 2nd pins of the operational amplifier chip U10 are connected with the other end of the capacitor C61 to the signal CVD, and the 6th and 7th pins of the operational amplifier chip U10 are connected with the other end of the capacitor C62 to the signal CCD. The protection circuit is used for sampling the voltage and current signals of the inverter bridge and feeding back to the main controller, so as to realize the system safety protection.

[0033] The embodiment fully applies the DSP control technology, the high-frequency switching power supply technology and the power device integration technology, and designs a simple and practical low-power frequency converter circuit with comprehensive functions and high cost performance. First, the switching power supply technology is applied to design a low-voltage direct-current power supply. Second, the rectification bridge and the large capacitor are applied to design a rectification filter circuit. Third, the MOS tube and the large power resistor are applied to design a braking discharge circuit. Fourth, the intelligent power module IPM is applied to design an inverter bridge with strong anti-interference capability. Fifth, the main controller DSP chip TMS320LF2406 is applied to conveniently realize the motor control algorithm and generate six SVPWM pulses, so as to realize the variable-frequency variable-voltage energy-saving control of the motor. Sixth, the frequency converter is designed with an overvoltage, over-temperature and overcurrent protection circuit. If the circuit fails, the frequency converter can timely send a blocking signal to block the IPM module and the system circuit. Therefore, the frequency converter comprehensively applies various advanced technologies, has comprehensive functions, high cost performance and safety and energy saving.

Claims

1. A simple and practical low power inverter circuit comprising: The utility model relates to a kind of switch power supply, rectification filter circuit, brake discharge circuit, three-phase inverter circuit, main controller circuit and protection circuit;Characterized by: The switch power supply is connected with rectification filter circuit, brake discharge circuit, three-phase inverter circuit, main controller circuit and protection circuit, which is used to generate the required DC low-voltage power supply of system; The rectification filter circuit is connected with switch power supply, brake discharge circuit, three-phase inverter circuit and protection circuit, which is used to convert the input 220V AC into DC; The brake discharge circuit is connected with switch power supply, rectification filter circuit, three-phase inverter circuit and main controller circuit, which is used to open the circuit when the motor brake is braked to let the brake resistance consume the feedback energy, suppress the bus voltage rise and protect components; The three-phase inverter circuit is connected with switch power supply, rectification filter circuit, brake discharge circuit, main controller circuit and protection circuit, which is used to invert the DC voltage into variable-frequency variable-voltage three-phase AC voltage to drive the motor to run energy-efficiently; The main controller circuit is connected with switch power supply, brake discharge circuit, three-phase inverter circuit and protection circuit, which is used to accept external signals and output the required control signals of motor operation through control algorithm to control the motor to run as required; The protection circuit is connected with switch power supply, rectification filter circuit, three-phase inverter circuit and main controller circuit, which is used to sample the voltage and current signals of inverter bridge and feed back to the main controller; The switch power supply contains resistance R1~R15, capacitor C1~C20, inductance L1~L3, diode D1~D8, Schottky diode Z1, transformer TR1, photoelectric coupling OC1, switch power supply chip U1, voltage stabilizing source chip U2, U3, filter LCL, light emitting diode D9; wherein: the negative pole of capacitor C1, C3, C6, C8~C11, C13, C17, the positive pole of capacitor C15 and C16, one end of capacitor C2, C4, C12, C14, C18, the 2nd pin of switch power supply chip U1, the 1st pin of switch power supply chip U2, the 2nd pin of filter LCL, one end of resistance R10~R12, the 5th pin of voltage stabilizing source chip U3 and the 4th, 7th pin of transformer TR1 are connected with ground terminal, the negative pole of capacitor C19, one end of capacitor C20 and the 10th pin of transformer TR1 are connected with isolated ground terminal, one end of resistance R1 and the positive pole of capacitor C1 are connected with signal DRIVE, the other end of resistance R1 and the negative pole of diode D2 are connected, the positive pole of diode D2 and D3 is connected with the 3rd pin of transformer TR1, the negative pole of diode D3 is connected with one end of resistance R2, the other end of resistance R2 and the other end of capacitor C2, the positive pole of capacitor C3 and the 4th pin of photoelectric coupling OC1 are connected, the other end of capacitor C4 and the positive pole of Schottky diode Z1, resistance R3 and one end of capacitor C5 and the 1st pin of transformer TR1 are connected with PV, the negative pole of Schottky diode Z1 and the other end of resistance R3 and capacitor C5 and the negative pole of diode D1 are connected, the positive pole of diode D1 and the 3rd pin of switch power supply chip U1 and the 2nd pin of transformer TR1 are connected, the 1st pin of switch power supply chip U1 and one end of resistance R4 and the 3rd pin of photoelectric coupling OC1 are connected, the other end of resistance R4 and the positive pole of capacitor C6 are connected, the 1st pin of photoelectric coupling OC1 and one end of resistance R5 and R6 are connected, the other end of resistance R5 is connected with signal PO+, the other end of resistance R6 and the 1st pin of voltage stabilizing source chip U3 are connected, the 2nd pin of photoelectric coupling OC1 and one end of resistance R7 are connected, the other end of resistance R7 and one end of capacitor C7 are connected, one end of resistance R8, R9 is connected with signal +5V, +15V respectively, the other end of capacitor C7 and the other end of resistance R8~R10 and the 8th pin of voltage stabilizing source chip U3 are connected, the positive pole of diode D4~D7 is connected with the 5th, 6th, 8th, 9th pin of transformer TR1 respectively, the negative pole of diode D4 and one end of inductance L1 and the positive pole of capacitor C8 are connected with signal PO+, the other end of inductance L1 and the positive pole of capacitor C9 are connected with signal +15V, the negative pole of diode D5 and one end of inductance L2 and the positive pole of capacitor C10 are connected, the other end of inductance L2 and the positive pole of capacitor C11, the other end of capacitor C12, the 3rd pin of voltage stabilizing source chip U2 are connected with signal +5V, the 2nd pin of voltage stabilizing source chip U2 and the positive pole of capacitor C13, the other end of capacitor C14 and the 1st pin of filter LCL are connected, the 3rd pin of filter LCL and the positive pole of light emitting diode D9 are connected with +3.3V, the negative pole of the light emitting diode D9 is connected with the other end of the resistor R11, the negative pole of the diode D8 is connected with the positive pole of the diode D6, the positive pole of the diode D8, the negative pole of the capacitor C15 and one end of the inductor L3 are connected, the other end of the inductor L3 and the negative pole of the capacitor C16 are connected with the signal -15V, the negative pole of the diode D6 is connected with one end of the resistor R13, the other end of the resistor R13, the positive pole of the capacitor C17 and one end of the resistor R14 are connected, the other ends of the resistors R12, R14 and the other end of the capacitor C18 are connected with the signal CVD, the negative pole of the diode D7 is connected with the positive pole of the capacitor C19, the capacitor C20 and the other end of the resistor R15 with the signal +24V; The rectification filter circuit comprises fuse FU1, voltage-dependent resistor R16-R18, resistor R19, capacitor C21-C24, filter L1, rectifier bridge B1, relay RL1 and diode D10;One end of fuse FU1 is connected to one end of AC 220 AC power supply, one end of voltage-dependent resistor R16 and R18 and capacitor C22 is connected to the other end of AC 220 AC power supply, the other end of fuse FU1 and voltage-dependent resistor R16 is connected to one end of voltage-dependent resistor R17, capacitor C21 and the first pin of filter L1, the other end of voltage-dependent resistor R17, R18 and capacitor C21, C22 is connected to the second pin of filter L1, the third and fourth pins of filter L1 are respectively connected to both ends of capacitor C23 and the first and third pins of rectifier bridge B1, the third pin of rectifier bridge B1 is connected to strong electric ground, the second pin of rectifier bridge B1 is connected to the positive electrode of capacitor C24 and the second pin of relay RL1 to signal PV, the fourth pin of rectifier bridge B1 is connected to one end of resistor R19, the other end of resistor R19 is connected to the negative electrode of capacitor C24 to signal-PV, the third pin of relay RL1 is suspended, the first pin of relay RL1 is connected to signal PG, the fifth pin of relay RL1 is connected to the negative electrode of diode D10 to signal +5V, and the fourth pin of relay RL1 is connected to the positive electrode of diode D10 to ground. The brake discharge circuit comprises resistors R20-R24, capacitors C25-C26, a diode D11, an optical coupler OC2 and a MOS transistor Q2; wherein one end of the resistor R20 is connected to a signal PWMBrake, the other end of the resistor R20 is connected to the capacitor C25, one end of the resistor R21 and the third pin of the optical coupler OC2, the other end of the capacitor C25 and the resistor R21 is connected to the second pin of the optical coupler OC2 and a signal +5V, the sixth and seventh pins of the optical coupler OC2 are connected to one end of the resistor R22, the other end of the resistor R22 is connected to the resistor R23, one end of the capacitor C26 and the gate G of the MOS transistor Q2, the source S of the MOS transistor Q2 is connected to a signal -PV, the drain D of the MOS transistor Q2 is connected to one end of the resistor R24 and the positive electrode of the diode D11, the other end of the resistor R24 and the negative electrode of the diode D11 is connected to a signal PV, the resistor R23 and the other end of the capacitor C26 are connected to the fifth pin of the optical coupler OC2 and a ground, and the eighth pin of the optical coupler OC2 is connected to a DRIVER signal. The three-phase inverter circuit comprises resistors R26-R30, capacitors C30-C42, diodes D12-D14, IPM module U6, Hall sensors U4-U5, and asynchronous motor M; wherein: one end of capacitor C30 is connected to the positive poles of diodes D12-D14, one end of capacitor C34, and the 14th pin of IPM module U6 to signal DRIVE; the other ends of capacitors C30 and C34 are connected to one end of capacitors C31-C33 to the ground end; the other ends of capacitors C31-C33 are respectively connected to the 2nd, 6th, and 10th pins of IPM module U6; the negative poles of diodes D12-D14 are respectively connected to one end of resistors R26-R28; the other end of resistor R26 is connected to the positive pole of capacitor C35, one end of capacitor C36, and the 3rd pin of IPM module U6; the negative pole of capacitor C35 is connected to the other end of capacitor C36 and the 4th pin of IPM module U6; the other end of resistor R27 is connected to the positive pole of capacitor C37, one end of capacitor C38, and the 7th pin of IPM module U6; the negative pole of capacitor C37 is connected to the other end of capacitor C38 and the 8th pin of IPM module U6; the other end of resistor R28 is connected to the positive pole of capacitor C39, one end of capacitor C40, and the 12th pin of IPM module U6; the negative pole of capacitor C39 is connected to the other end of capacitor C40 and the 13th pin of IPM module U6; the 1st, 5th, 9th, 19th, 20th, 21st, 18th, 22nd, and 11th pins of IPM module U6 are respectively connected to signals PWMU+, PWMV+, PWMW+, PWMU-, PWMV-, PWMW-, FO signal, PG signal, and strong electric ground signal; the 23rd-25th pins of IPM module U6 are respectively connected to the U, V, and W pins of asynchronous motor M; the 6th pins of Hall sensors U4 and U5 are respectively connected to the U and V pins of asynchronous motor M; the 1st pins of Hall sensors U4 and U5 are connected to signal -15V; the 3rd pins of Hall sensors U4 and U5 are connected to signal +15V; the 2nd pins of Hall sensors U4 and U5 are connected to the ground end; the 4th pins of Hall sensors U4 and U5 are respectively connected to signals IUsensor and IVsensor; the 26th pin of IPM module U6 is connected to one end of resistors R29 and R30 to signal PIsensor; the 16th pin of IPM module U6 is connected to the other end of resistor R29 and one end of capacitor C41; one end of capacitor C42 is connected to the 17th pin of IPM module U6; the other ends of capacitors C41 and C42 are connected to the other end of resistor R30 to the ground end. The main controller circuit contains resistance R35-R41, capacitor C45-C52, light emitting diode D15, crystal oscillator XTAL1, DSP chip U7, reset chip U8, memory chip U9; wherein: the 40th pin of the DSP chip U7 is connected with +5V, the 20th, 35th, 59th, 91st, 4th, 30th, 47th, 54th, 64th, 98th pin of the DSP chip U7 and the 3rd pin of the reset chip U8 are connected with +3.3V, the 84th, 19th, 34th, 58th, 90th, 3rd, 29th, 46th, 53rd, 63rd, 97th pin of the DSP chip U7 are connected with the ground terminal, the 39th, 37th, 36th, 33rd, 31st, 28th, 12th, 13th, 6th, 51st, 23rd, 24th, 1st, 67th, 69th, 70th, 77th, 79th pin of the DSP chip U7 are connected with signal PWMU+, PWMV+, PWMW+, PWMU-, PWMV-, PWMW-, IOPB4, IOPB5, FO, short, DRIVE, PWMBrake, TRST, CVD, CCD, AGND, IA, IB respectively, the 1st pin of the reset chip U8 is connected with the negative pole of the light emitting diode D15, one end of the capacitor C45, one end of the capacitor C49-C51, the negative pole of the capacitor C52 and the 1st-4th, 7th pin of the memory chip U9 with the ground terminal, the 93rd pin of the DSP chip U7 is connected with one end of the resistance R35 and the other end of the capacitor C45 with signal RST, the other end of the resistance R35 is connected with the 2nd pin of the reset chip U8, one end of the capacitor C46-C48 is connected with the 8th pin of the DSP chip U7, the other end of the capacitor C46, C47 is connected with the 9th pin of the DSP chip U7 and one end of the resistance R36, the other end of the resistance R36 is connected with the other end of the capacitor C48, one end of the resistance R37 is connected with the 86th pin of the DSP chip U7 with signal XF, the other end of the resistance R37 is connected with the positive pole of the light emitting diode D15, the other end of the capacitor C51, the positive pole of the capacitor C52 is connected with the 10th pin of the DSP chip U7 with +3.3V, one end of the resistance R38 is connected with the 88th pin of the DSP chip U7, the other end of the resistance R38 is connected with one end of the resistance R39, one end of the crystal oscillator XTAL1, the other end of the capacitor C49, the other end of the resistance R39 is connected with the other end of the crystal oscillator XTAL1, the 87th pin of the DSP chip U7, the other end of the capacitor C50, the 8th pin of the memory chip U9 is connected with one end of the resistance R40, R41 with +3.3V, the other end of the resistance R40, R41 is connected with the 6th, 5th pin of the memory chip U9 with signal IOPB4, IOPB5 respectively; The protection circuit contains resistance R45-R50, capacitor C55-C62, voltage stabilizing tube Z2, operational amplifier chip U10; wherein: one end of capacitor C55-C62, one end of resistance R48 and positive pole of voltage stabilizing tube Z2 are connected to ground terminal, one end of resistance R45 and the other end of capacitor C55 are connected to signal IUsensor, one end of resistance R46 and the other end of capacitor C56 are connected to signal IVsensor, one end of resistance R47 is connected to signal PG, the other end of resistance R47, the other end of capacitor C59, negative pole of voltage stabilizing tube Z2, the other end of resistance R48 and one end of resistance R49 are connected to signal PVsensor, one end of resistance R50 and the other end of capacitor C60 are connected to signal PIsensor, the other end of resistance R45, R46, R49 and R50 are connected to the 10th, 12th, 3rd and 5th pin of operational amplifier chip U10 respectively, the 8th and 9th pin of operational amplifier chip U10 are connected to signal IA through the other end of capacitor C57, the 13th and 14th pin of operational amplifier chip U10 are connected to signal IB through the other end of capacitor C58, the 4th and 11th pin of operational amplifier chip U10 are connected to one end of capacitor C63 and C64 respectively, the other end of capacitor C63 and C64 are connected to signal AGND, the 1st and 2nd pin of operational amplifier chip U10 are connected to signal CVD through the other end of capacitor C61, the 6th and 7th pin of operational amplifier chip U10 are connected to signal CCD through the other end of capacitor C62.

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