CN115800827A

CN115800827A - Low-cost direct current frequency conversion lampblack absorber EMC circuit

Info

Publication number: CN115800827A
Application number: CN202211376809.5A
Authority: CN
Inventors: 葛群虎; 赵江; 季成; 孙茂植; 朱大鹏; 朱巨华; 麻赵畅; 张佑宇; 竺志敏; 马锦
Original assignee: Phoenix Intelligent Electronics Hangzhou Co ltd
Current assignee: Phoenix Intelligent Electronics Hangzhou Co ltd
Priority date: 2022-11-04
Filing date: 2022-11-04
Publication date: 2023-03-14
Anticipated expiration: 2042-11-04
Also published as: CN115800827B

Abstract

The invention discloses a low-cost direct current frequency conversion range hood EMC circuit, which comprises a first MCU, a second MCU, a motor driving module and a power source EMC module, wherein the first MCU is used for issuing output parameters of a direct current frequency conversion motor to the second MCU; the motor driving module comprises an IPM module, a first socket CN3, a fuse F2, an electrolytic capacitor C59, a capacitor C60, a plurality of bootstrap circuits and a plurality of RC circuits and is used for driving the direct-current variable-frequency motor; the power supply EMC module is used for supplying power and realizing the charging of the electrolytic capacitor C59 when the power supply EMC module is powered on so as to prevent sparks from being generated. The circuit can effectively suppress disturbance voltage and disturbance power interference from the source, simplifies the power supply end into single-stage filtering, is beneficial to realizing small and light weight, reduces cost, shortens the research and development period, and has high reliability and wide application range.

Description

Low-cost direct current frequency conversion lampblack absorber EMC circuit

Technical Field

The invention belongs to the technical field of EMC circuits, and particularly relates to an EMC circuit of a low-cost direct-current frequency conversion range hood.

Background

In recent years, the use of direct current frequency conversion control technology on household electrical appliances is becoming mature, and direct current frequency conversion range hoods become mainstream in the range hood market gradually. The direct current frequency conversion technology is that 220V voltage is rectified by a rectifier bridge to form high-voltage direct current, and the MCU outputs high-frequency signals to control the switching tubes at the high-voltage end and the low-voltage end in the power module to be sequentially switched on and off so as to drive three windings of the motor.

Direct current voltage adjusts duty ratio through MCU and controls the FOC control mode that the motor winding produced similar sinusoidal current, and direct current power supply can produce serious disturbance voltage and the EMC interference of disturbance power under the high frequency switch condition, if direct current frequency conversion lampblack absorber usually samples high frequency 13-18K carrier frequency control power device drive direct current variable frequency motor. The 220V alternating current power supply is about 310V direct current voltage after being rectified by the rectifier bridge, the three-phase high-voltage half-bridge circuit is controlled to be sequentially conducted up and down through the MCU to enable the motor winding to generate an FOC control mode similar to sine wave current, a severe work mode interference source and a differential mode interference source can be generated under the condition of direct current voltage high-frequency switching, and interference on a power supply circuit under the working state of a direct current frequency conversion board can be visually observed through a disturbance voltage and disturbance power tester. The main interference frequency bands of the frequency conversion range hood are a 20-26MHz interference voltage frequency band and a 30-40MHz interference voltage frequency band.

An EMC circuit of a conventional direct-current frequency conversion range hood controller generally adopts a two-stage series connection mode of a one-stage large-capacity X capacitor and a common mode inductor which are connected in series with a one-stage small-capacity X capacitor to process a mode inductor, and low-frequency disturbance voltage interference and partial high-frequency interference are inhibited. And a three-phase common-mode inductor is arranged at the output end of the motor to inhibit high-frequency disturbance. Generally, the EMC test margin of the whole machine is still low by adopting the two measures. A special EMC suppressor is added at a power supply end by part of manufacturers to improve the EMC test allowance. In order to ensure that the safety plug reaches a safe voltage lower than 36V and national standard standby power consumption required by design in the alternating current top power-off 1S after discharging, a top discharge chip is connected in parallel at the X capacitor end. By the aid of the common mode inductor, more components are added, the PCB needs to be large in size in layout, the cost of the components is increased, the common mode inductor generates large heat under the full load condition, and the stability of the control panel is influenced to a certain extent. Compared with the traditional alternating current motor, the control mode of the existing direct current frequency conversion technology is complex, and the requirement on designers is high.

In the scheme, the voltage mutation of DV/Dt in the switching process is reduced, the played effect is relatively limited, disturbance voltage and disturbance power are restrained by matching the power supply end bipolar filter circuit, the size and cost of the controller are increased, the price of a direct current frequency conversion product is high, the realized EMC allowance is small, the matching needs to be debugged again even if the same control board has slight difference between different air ducts of the range hood and the motor, and time and labor are wasted in research and development. Therefore, how to effectively inhibit the DV/Dt voltage sudden change of the IPM module of the direct current variable frequency controller in the bridge arm switching process is particularly important.

Disclosure of Invention

The invention aims to solve the problems, provides the low-cost direct-current frequency conversion range hood EMC circuit which can effectively inhibit disturbance voltage and disturbance power interference from a source, simplifies power supply ends into single-stage filtering, is beneficial to realizing small and light weight, reduces cost, shortens development and development periods, and is high in reliability and wide in application range.

In order to realize the purpose, the technical scheme adopted by the invention is as follows:

the invention provides a low-cost direct current frequency conversion range hood EMC circuit, which is applied to a range hood, wherein the range hood comprises a direct current frequency conversion motor for driving a fan, the low-cost direct current frequency conversion range hood EMC circuit comprises a first MCU, a second MCU, a motor driving module and a power supply EMC module, and the low-cost direct current frequency conversion range hood EMC circuit comprises a first MCU, a second MCU, a motor driving module and a power supply EMC module, wherein:

the first MCU is used for issuing output parameters of the direct current variable frequency motor to the second MCU, the second MCU controls the direct current variable frequency motor to move according to the received output parameters of the direct current variable frequency motor, and returns motor running state data to the first MCU;

the motor driving module comprises an IPM module, a first socket CN3, a fuse F2, an electrolytic capacitor C59, a capacitor C60, a plurality of bootstrap circuits and a plurality of RC circuits, wherein the bootstrap circuits comprise two bootstrap capacitors connected in parallel, and the steps of:

two ends of the fuse F2 are respectively connected with the anode of the electrolytic capacitor C59 and one end of the capacitor C60, the cathode of the electrolytic capacitor C59 is grounded with the other end of the capacitor C60, and the common end of the fuse F2 and the capacitor C60 is also connected with the direct-current voltage positive end of the IPM module;

the W-phase output end, the V-phase output end, the U-phase output end, the W-phase driving positive end, the V-phase driving positive end and the U-phase driving positive end of the upper bridge arm of the IPM module are all grounded through RC circuits, the W-phase output end, the V-phase output end and the U-phase output end of the IPM module are sequentially connected with the W-phase driving positive end, the V-phase driving positive end and the U-phase driving positive end of the upper bridge arm of the IPM module in a one-to-one correspondence manner through bootstrap circuits, the W-phase direct-current power negative end, the V-phase direct-current power negative end and the U-phase direct-current power negative end of the IPM module are all grounded, the W-phase logic input end, the lower bridge arm V-phase logic input end, the U-phase logic input end, the upper half bridge W-phase logic input end and the upper half bridge V-phase logic input end of the IPM module are all connected with a second MCU, the conduction or disconnection of the upper bridge arm or the lower bridge arm of the IPM module is realized through the control of the second MCU, the lower bridge arm reference ground end of the lower bridge arm of the IPM module is grounded, and is used for controlling the power supply output end of the first power supply socket and the corresponding to the first inverter W-phase output end of the IPM motor, and the third output end of the IPM motor, which is connected with the corresponding to the third DC motor, and the CN;

and the power supply EMC module is used for supplying power and realizing the charging of the electrolytic capacitor C59 to prevent sparks from being generated when power is on.

Preferably, the first MCU communicates with the second MCU through the optocoupler-isolated serial port.

Preferably, the power supply voltage of the positive terminal of the control power supply of the IPM module is +15V to +20V.

Preferably, the motor driving module further comprises a protection circuit, the protection circuit comprises a capacitor C54, a capacitor C55 and a voltage regulator tube D9, the capacitor C54 and the capacitor C55 are connected in parallel, two ends of the capacitor C54 and two ends of the capacitor C55 are respectively connected with two ends of the voltage regulator tube D9, the anode of the voltage regulator tube D9 is grounded, and the cathode of the voltage regulator tube D9 is connected with the positive end of the control power supply of the IPM module.

Preferably, the power EMC module comprises a front-end circuit, a regulating circuit, a common-mode inductance TF1 and a back-end circuit, wherein:

a first pin and a second pin of the common-mode inductor TF1 form a first winding, and a third pin and a fourth pin form a second winding;

the front-end circuit comprises a power plug AC1, a fuse F1, a piezoresistor ZE1, a capacitor C20 and a thermistor NTC1, wherein a live wire of the power plug AC1 is connected with one end of the piezoresistor ZE1 through the fuse F1, a zero line is connected with the other end of the piezoresistor ZE1, the piezoresistor ZE1 is also connected with the capacitor C20 in parallel, one end of the capacitor C20 is connected with a second pin of the common-mode inductor TF1, and the other end of the capacitor C20 is connected with a third pin of the common-mode inductor TF1 through the thermistor NTC 1;

the adjusting circuit comprises a relay RL1, a diode D9, an NPN triode Q4, a resistor R31 and a resistor R37, wherein two ends of the resistor R37 are respectively connected with a base electrode and an emitting electrode of the NPN triode Q4, the emitting electrode of the NPN triode Q4 is grounded, one end of the resistor R31 is connected with the base electrode of the NPN triode Q4, the other end of the resistor R31 is connected with a first MCU (microprogrammed control unit), a collector electrode of the NPN triode Q4 and one end of a coil of the relay RL1 are both connected with an anode of the diode D9, a cathode of the diode D9 and the other end of the coil of the relay RL1 are both connected with a power supply anode, and a moving contact and a static contact of the relay RL1 are respectively connected with two ends of a thermistor NTC 1;

the rear-end circuit comprises a resistor R89, a resistor R90, an inductor L1, a capacitor C15, a capacitor C21, a capacitor C22, a rectifier bridge DB1, a piezoresistor ZE2, a capacitor C28 and a capacitor C29, wherein the resistor R89 and the resistor R90 are connected to two ends of the capacitor C21 in series, one end of the capacitor C21 is connected with a first pin of the common-mode inductor TF1 and one end of the inductor L1 respectively, one ends of the capacitor C15 and the capacitor C22 are grounded, the other end of the capacitor C15 is connected with the other end of the inductor L1 and a first input end of the rectifier bridge DB1 respectively, the other ends of the capacitor C21 and the capacitor C22 and a second input end of the rectifier bridge DB1 are connected with a fourth pin of the common-mode inductor TF1, one end of the piezoresistor ZE2 is connected with a positive output end of the rectifier bridge DB1 and a positive electrode of the electrolytic capacitor C59 respectively, the other end of the capacitor C28 and the other end of the capacitor C29 are grounded.

Preferably, the motor driving module further includes a resistor R53, a resistor R56, and a capacitor C45, the W-phase dc power supply negative terminal, the V-phase dc power supply negative terminal, and the U-phase dc power supply negative terminal of the IPM module are connected to each other, the W-phase dc power supply negative terminal of the IPM module is grounded through the resistor R53, and the U-phase dc power supply negative terminal of the IPM module is grounded through the resistor R56 and the capacitor C45 in sequence.

Preferably, the low-cost direct current frequency conversion range hood EMC circuit further comprises a current detection signal amplification module, the current detection signal amplification module comprises a resistor R30, a resistor R33, a resistor R40, a resistor R47, a resistor R48, a capacitor C78 and an operational amplifier, wherein:

the resistor R33, the resistor R30, the capacitor C78, the resistor R40 and the resistor R47 are sequentially connected, the common end of the resistor R30 and the capacitor C78 is grounded, the common end of the capacitor C78 and the resistor R40 is connected with the negative end of a W-phase direct-current power supply of the IPM module, the common end of the resistor R33 and the resistor R30 is connected with the inverting input end of the operational amplifier, the other end of the resistor R33 is connected with the output end of the operational amplifier, the common end of the resistor R40 and the common end of the resistor R47 are respectively connected with the non-inverting input end of the operational amplifier and one end of the resistor R48, the other end of the resistor R47 is grounded, the other end of the resistor R48 is connected with +5V voltage, and the resistor R47 and the resistor R48 form 2.5V bias voltage.

Preferably, the operational amplifier has a magnification of 11 times.

Preferably, the low-cost direct current frequency conversion range hood EMC circuit further comprises a counter electromotive force detection module, the counter electromotive force detection module comprises a resistor R23, a resistor R24, a resistor R25, a resistor R34, a resistor R35, a resistor R36, a resistor R41, a resistor R42, a resistor R43, a resistor R49, a resistor R50, a resistor R51, a capacitor C35, a capacitor C36 and a capacitor C37, wherein:

the resistor R23, the resistor R24 and the resistor R25 are sequentially connected, one ends of the resistor R49 and the capacitor C35 are connected with the common end of the resistor R23 and the resistor R24, and the other ends are grounded;

the resistor R34, the resistor R35 and the resistor R36 are sequentially connected, one end of the resistor R50 and one end of the capacitor C36 are both connected with the common end of the resistor R34 and the resistor R35, and the other ends are grounded;

the resistor R41, the resistor R42 and the resistor R43 are sequentially connected, one end of the resistor R51 and one end of the capacitor C37 are both connected with the common end of the resistor R41 and the resistor R42, and the other ends are connected with the ground;

one ends, far away from the connected resistors, of the resistor R25, the resistor R36 and the resistor R43 are further connected with the U-phase output end, the V-phase output end and the W-phase output end of the IPM module in a one-to-one corresponding mode, and one ends, far away from the connected resistors, of the resistor R23, the resistor R34 and the resistor R41 are correspondingly connected with the AD sampling interface of the second MCU.

Preferably, the IPM module employs a 600V 6A IGBT driver chip.

Compared with the prior art, the invention has the following beneficial effects:

1) According to the circuit, a direct-current variable-frequency interference source is inhibited at the source of the direct-current variable-frequency EMC, namely, inhibition analysis is carried out on disturbance voltage and disturbance power interference source parts generated by an IPM module, an RC absorption circuit is matched at the output end of a three-phase motor, and an RC absorption circuit is matched at the end of a bootstrap circuit, so that disturbance voltage and disturbance power are effectively inhibited, three-phase common-mode filter inductors required by the direct-current variable-frequency EMC in the prior art are removed, bipolar filtering at the input end is simplified to single-machine filtering, a top discharge chip is removed while primary common-mode inductors and X capacitors are reduced, the layout of a PCB is simpler, the realization of small-size light weight and cost reduction is facilitated, the reliability is high, and the application range is wide;

2) This circuit EMC design allowance is bigger, helps realizing direct current frequency conversion control platformization design, matches different grade type motor or lampblack absorber model and only adjusts software, and need not hardware adjustment can high efficiency realize the development, shortens the research and development cycle greatly.

Drawings

FIG. 1 is a schematic structural diagram of an EMC circuit of a low-cost direct current frequency conversion range hood;

FIG. 2 is a circuit diagram of a motor drive module of the present invention;

fig. 3 is a circuit diagram of the power EMC module of the present invention;

FIG. 4 is a circuit diagram of a current sense signal amplification module according to the present invention;

FIG. 5 is a circuit diagram of a back EMF detection module according to the present invention;

FIG. 6 is a diagram of disturbance voltage detection results of the present invention;

FIG. 7 is a diagram of disturbance power detection results of the present invention;

FIG. 8 is a diagram of disturbance voltage detection results of the prior art;

fig. 9 is a diagram of a disturbance power detection result in the prior art.

Detailed Description

The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application, and it is obvious that the described embodiments are only a part of the embodiments of the present application, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application.

It will be understood that when an element is referred to as being "connected" to another element, it can be directly connected to the other element or intervening elements may also be present. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used in the description of the present application herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application.

As shown in fig. 1-7, a low-cost direct current frequency conversion lampblack absorber EMC circuit is applied to the lampblack absorber, and the lampblack absorber is including the direct current inverter motor who is used for driving the fan, and low-cost direct current frequency conversion lampblack absorber EMC circuit includes first MCU, second MCU, motor drive module and power EMC module, wherein:

and the power supply EMC module is used for supplying power and realizing the charging of the electrolytic capacitor C59 to prevent sparks from being generated when the power supply EMC module is powered on.

The range hood can be of any structure in the prior art, such as a direct current variable frequency motor, a fan and a man-machine board, and a circuit usually adopts a single and special direct current variable frequency motor control chip (second MCU) to control the motion of the direct current variable frequency motor. And the first MCU and the second MCU can be integrated on the same PCB or designed in a split mode. The main control chip (first MCU) is used for overall logic control, and is interacted with the man-machine board through serial port communication to acquire the key information and the setting state of the man-machine board, and the running state data of the first MCU is sent to the man-machine board, and the man-machine board displays the key information and the setting state to a user through an LED screen or an LED lamp. The first MCU communicates with the second MCU through the optical coupling isolation serial port communication, the output parameters required by the direct current variable frequency motor are sent to the second MCU, and the second MCU sends the motor running state data back to the first MCU. It should be noted that, 6-10W of LED lamps are generally installed on the range hood as illumination, the LED lamps are controlled to be switched on and off through the first MCU, if the side-draft range hood is a side-draft range hood, the electric push rod is controlled by the first MCU to realize turnover of the turning plate, and the specific number of the LED lamps and the electric push rod can be adjusted according to actual requirements.

In the embodiment, the maximum input power of the direct-current variable frequency motor is 380W, the static pressure of the range hood is 1000 Pa, and the air volume is 24 cubic. For realizing 380W maximum input power module, an IPM module of 600V 6A IGBT is adopted to drive a direct-current variable-frequency motor, if the IPM module is XNS06S72F6, in order to ensure effective heat dissipation, the IPM module is packaged by DIP-25, and a large heat dissipation fin is attached to a metal cover of a control plate of a range hood through heat-conducting silica gel to realize effective heat dissipation. In the figure, SGND is not isolated, and AGND is a power supply ground.

In one embodiment, the first MCU communicates with the second MCU through the optocoupler-isolated serial port.

In one embodiment, the power supply voltage of the positive terminal of the control power supply of the IPM module is +15V to +20V.

In an embodiment, the motor driving module further includes a protection circuit, the protection circuit includes a capacitor C54, a capacitor C55 and a voltage regulator tube D9, the capacitor C54 and the capacitor C55 are connected in parallel, and two ends of the capacitor C54 and the capacitor C55 are respectively connected with two ends of the voltage regulator tube D9, an anode of the voltage regulator tube D9 is grounded, and a cathode of the voltage regulator tube D9 is connected with a positive terminal of a control power supply of the IPM module.

Specifically, as shown in fig. 2, the motor driving module includes an IPM module, a first socket CN3, a fuse F2, an electrolytic capacitor C59, a capacitor C60, a resistor R53, a resistor R56, a capacitor C45, a capacitor C54, a capacitor C55, a voltage regulator D9, a resistor R58, a resistor R59, a resistor R62, a resistor R63, a resistor R64, a resistor R65, a capacitor C40, a capacitor C41, a capacitor C42, a capacitor C50, a capacitor C51, a capacitor C52, a resistor R76, a resistor R32, a capacitor C90, a capacitor C91, a capacitor C92, a capacitor C53, a capacitor C56, a capacitor C58, a capacitor C61, a capacitor C62, a capacitor C63, a capacitor C16, a capacitor C85, and a capacitor C86, wherein:

the reference ground end (including pins 9 and 16) of the lower bridge arm of the IPM module is grounded, power is supplied through the positive end (including pins 8 and 13) of the control power supply of the IPM module, and a voltage regulator tube D9 in the protection circuit is a voltage regulator diode for protection, so that the IPM module is prevented from being damaged. The positive end of the control power supply of the IPM module is an internal drive power supply end, the maximum power supply voltage is +20V, and the commonly used power supply voltage is +15V.

The lower bridge arm W-phase logic input end, the lower bridge arm V-phase logic input end, the lower bridge arm U-phase logic input end, the upper half bridge W-phase logic input end, the upper half bridge V-phase logic input end and the upper half bridge U-phase logic input end (which correspond to

pins

12, 11, 10, 7, 6 and 5 in sequence) of the IPM module are all connected with a second MCU, a resistor of 20-47 omega is generally connected between the second MCU and the input end of the IPM module in series, meanwhile, a ceramic chip capacitor of 100pF is placed at the input end of the IPM module to reduce signal interference, and the upper bridge arm or the lower bridge arm of the IPM module is controlled to be switched on or switched off by the second MCU. Specifically, one end of the resistor R58, one end of the resistor R59, and one end of the resistor R62 are sequentially connected to the 12 th pin, the 11 th pin, and the 10 th pin of the IPM module, and the other end of the resistor R is correspondingly connected to the second MCU, one end of the capacitor C40, one end of the capacitor C41, and one end of the capacitor C42 are connected to the ground, and the other end of the capacitor C42 are sequentially connected to the 12 th pin, the 11 th pin, and the 10 th pin of the IPM module, respectively, the second MCU controls the 12 th pin, the 11 th pin, and the 10 th pin of the IPM module to turn on or off the lower arm of the IPM module, one end of the resistor R63, one end of the resistor R64, and one end of the resistor R65 are sequentially connected to the 7 th pin, the 6 th pin, and the 5 th pin of the IPM module, and the other end of the capacitor C50, one end of the capacitor C51, and one end of the capacitor C52 are connected to the ground, and the other end of the resistor R65 are sequentially connected to the 7 th pin, the 6 th pin, the 5 th pin of the IPM module, and the second MCU controls the upper arm of the IPM module to turn on or off the IPM module.

Two ends of the fuse F2 are respectively connected with the anode of the electrolytic capacitor C59 and one end of the capacitor C60, the cathode of the electrolytic capacitor C59 is connected with the other end of the capacitor C60 in common, and the common end (voltage VDC-1) of the fuse F2 and the capacitor C60 is also connected with the direct-current voltage positive end (24 th pin) of the IPM module. 220V alternating current input by the range hood is rectified by a rectifier bridge to obtain 310V direct current voltage VDC. An electrolytic capacitor C59 of 450V 330UF is arranged at the front end of the VDC for module power supply voltage stabilization, and the VDC is connected with a 3.15A fuse F2 in series to realize fuse fusing under the condition of short circuit of the direct current variable frequency motor, so that the software certification of the whole machine can be avoided. A CBB capacitor C60 of 630V 10nF is arranged at the rear end of the fuse F2, so that partial differential mode interference of the edge end of the direct-current variable-frequency motor can be absorbed, and burrs of a VDC power end in the working state are reduced.

The W-phase direct-current power supply negative end, the V-phase direct-current power supply negative end and the U-phase direct-current power supply negative end (pins 18, 19 and 20 in sequence) of the IPM module are connected with each other, the W-phase direct-current power supply negative end of the IPM module is grounded through a resistor R53, and the U-phase direct-current power supply negative end of the IPM module is grounded through a resistor R56 and a capacitor C45 in sequence. The sampling resistor adopts a single-resistor sampling mode, and a 2512 packaging patch 2W 0.2 ohm noninductive low-temperature drift alloy resistor R53 is used, so that accurate current sampling is ensured.

The W-phase output end, the V-phase output end, the U-phase output end, the W-phase driving positive end of the upper bridge arm, the V-phase driving positive end of the upper bridge arm, and the U-phase driving positive end of the upper bridge arm (sequentially 21 st, 22 nd, 23 th, 4 rd, 3 nd and 2 nd pins) of the upper bridge arm are all grounded through an RC circuit, specifically, a capacitor C53, a capacitor C56, a capacitor C58, a capacitor C61, a capacitor C62 and a capacitor C63 are boot strap capacitors, the capacitor C53 and the capacitor C56 are connected in parallel, two ends of the capacitor C53 and the capacitor C56 are respectively connected with the 2 nd pin and the 23 rd pin of the IPM module, the capacitor C58 and the capacitor C61 are connected in parallel, two ends of the capacitor C62 and the capacitor C63 are respectively connected with the 4 th pin and the 21 st pin of the IPM module to form a boot strap circuit, one end of the capacitors C90, C91 and C92 is sequentially connected with the 2 nd pin, the 3 rd pin and the 4 th pin of the IPM module, the other end of the capacitor C16, the capacitor C86, the first pin 23 nd pin of the IPM module is sequentially connected with the resistor R32, and the other end of the resistor R76.

The three wiring terminals of the first socket CN3 are respectively connected with the W-phase output terminal, the V-phase output terminal and the U-phase output terminal of the IPM module in a one-to-one correspondence manner, and are used for being correspondingly connected with the three-phase input terminal of the dc variable frequency motor, so that the same-phase corresponding connection between the three-phase input terminal of the dc variable frequency motor and the W-phase output terminal, the V-phase output terminal and the U-phase output terminal of the IPM module is realized.

In an embodiment, the power EMC module comprises a front-end circuit, a regulating circuit, a common-mode inductance TF1 and a back-end circuit, wherein:

The front-end circuit is provided with a 14K561 piezoresistor ZE1, the whole machine can normally work under the surge L-N2KV value, the L-ground value and the N-ground 4KV value in actual measurement, and an X capacitor C20 of 0.68uF is selected. Then to the back-end circuit via SQ1918-15mH common mode inductor TF 1. The rear-end circuit capacitor discharge resistor is connected in series by two 1206/270K resistors (a resistor R89 and a resistor R90), so that the safety voltage lower than 36V and the standby power consumption of the whole machine lower than 0.5W can be achieved when the safety plug AC1 discharges in the power-off 1S at the top end of the alternating current. And a silicon steel sheet inductor L1 of about EI2817 of 3.0mH is arranged at the rear end of the common mode inductor TF1, so that the harmonic current of the whole machine can meet the national standard requirement.

A Y1 capacitor (a capacitor C15 and a capacitor C22) with 22nF is respectively arranged at the front end L-earth and the N-earth of the rectifier bridge, a Y1 capacitor (a capacitor C28) with 22nF is arranged between the earth and the rear end earth of the rectifier bridge, and the dead point of the earth is connected across the Y capacitor with the rear end dead point of the rectifier bridge. The reasonable design of the Y capacitor is very effective for inhibiting the frequency band of the low-frequency disturbance voltage of 1-10M Hz. After disturbance voltage and disturbance power are effectively inhibited at an EMC source of the IPM module, an EMC circuit at a power input end can be effectively simplified, and only single-stage filtering is used, so that the inhibition effect of the disturbance voltage and the disturbance power is improved, and the cost and the size are reduced.

In one embodiment, the motor driving module further includes a resistor R53, a resistor R56, and a capacitor C45, wherein a W-phase dc power supply negative terminal, a V-phase dc power supply negative terminal, and a U-phase dc power supply negative terminal of the IPM module are connected to each other, the W-phase dc power supply negative terminal of the IPM module is grounded through the resistor R53, and the U-phase dc power supply negative terminal of the IPM module is grounded through the resistor R56 and the capacitor C45 in sequence.

In one embodiment, the low-cost direct current frequency conversion range hood EMC circuit further includes a current detection signal amplification module, the current detection signal amplification module includes a resistor R30, a resistor R33, a resistor R40, a resistor R47, a resistor R48, a capacitor C78 and an operational amplifier, wherein:

In one embodiment, the operational amplifier has a magnification of 11 times.

The current signal is sampled by the second MCU after being amplified by the operational amplifier, and the operational amplifier can be integrated in the second MCU, so that the integration level is high, the structure is compact, and the design is convenient. In this embodiment, the amplification factor of the operational amplifier is set to 11 times, and the bias voltage is half of the voltage of VDD 5V, i.e. 2.5V. It should be noted that the operational amplifier can be set independently of the second MCU, and the amplification factor of the operational amplifier and the bias voltage can be adjusted according to actual requirements.

In one embodiment, the low-cost direct current frequency conversion range hood EMC circuit further includes a counter electromotive force detection module, and the counter electromotive force detection module includes a resistor R23, a resistor R24, a resistor R25, a resistor R34, a resistor R35, a resistor R36, a resistor R41, a resistor R42, a resistor R43, a resistor R49, a resistor R50, a resistor R51, a capacitor C35, a capacitor C36, and a capacitor C37, where:

Under special conditions, the range hood has an upwind/downwind starting state, back electromotive force detection needs to be carried out on U, V, W three phases output, and the state of the direct-current variable-frequency motor before starting is detected, so that the direct-current variable-frequency motor is ensured to be started quickly and successfully. Signals of the U, V, W three-phase interface voltage of the IPM module are sampled by the AD sampling interface of the second MCU after being subjected to resistance voltage division, and the forward and reverse rotation state and the relative phase of the direct current variable frequency motor can be judged.

In one embodiment, the IPM module employs a 600V 6A IGBT driver chip.

The direct-current variable frequency motor realizes three-phase 120-degree phase angle sine wave current driving. Although the current waveform is a continuous sine wave, the IPM module reflects that the U-phase upper bridge arm is conducted, the lower bridge arm is turned off, the V-phase lower bridge arm is conducted, the upper bridge arm is turned off … …, and all the bridge arms are sequentially conducted in turn, and the duty ratio is adjusted in real time according to different load outputs. The switches of the bridge arms are always 310V high voltage and ground of VDC, and the direct current frequency conversion has larger DV/Dt voltage abrupt change interference, and particularly the abrupt change is particularly prominent in the phase switching process. And reflecting to an interference source with disturbance voltage interference of 10-30M Hz full-wave band. As shown in fig. 8 and 9, in the prior art, when EMC only uses simple bipolar filtering, the actual measurement effect of disturbance voltage is very unsatisfactory, the exceeding of the dc variable frequency motor in the 14M Hz band is very obvious, and the actual measurement of disturbance power is severely exceeded in the 30-60M Hz band.

According to the application, the RC absorption circuit is additionally arranged between the three phases (pins 21, 22 and 23) of the output U, V, W of the IPM module and the ground, so that voltage sudden change in the switching process of the IGBT in the IPM module can be reduced, and particularly, voltage sudden change of DV/Dt in the current commutation process can be reduced. And under the condition that only single-stage common mode filtering is used at the input end of the power supply, a 0-5.1 omega resistor R32 is connected in series between the U, V, W three-phase common point and the ground, so that 15-30M Hz disturbance voltage can be effectively inhibited.

In order to overcome high-frequency disturbance generated by the IPM module in the phase switching process of the 4 th, 3 rd and 2 nd pin bootstrap circuits and improve relative allowance of disturbance power, the RC absorption circuit is added at the front end (4 th, 3 rd and 2 nd pins) of the U, V, W three-phase bootstrap capacitor, so that the high-frequency disturbance of the bootstrap circuit can be inhibited.

In conclusion, the RC absorption circuit is added at the output end of the IPM module, the disturbance voltage of the direct-current frequency conversion range hood controller can be effectively inhibited under the condition that only a single-stage filter circuit is used at a power supply end, the actually measured disturbance voltage margin is more than 15DB, the RC absorption circuit is added at the front end of the bootstrap capacitor, the disturbance power can be effectively inhibited, and the actually measured disturbance power margin is more than 10 DB.

The working principle is as follows:

in the power-on process, an AC220V voltage is connected in through a power plug AC1, the electrolytic capacitor C59 is charged through a fuse F1, a thermistor NTC1, a common-mode inductor TF1, an inductor L1 (harmonic inductor) and a rectifier bridge DB1, and the thermistor NTC1 mainly serves to prevent potential safety hazards such as fire and the like caused by sparks generated by large current in the plug power-on process. Before the direct current variable frequency motor is started, because the relay RL1 is normally open, and is not closed at the moment, the NTC control end (namely the connecting end of the first MCU and the resistor R31) of the power supply EMC module is controlled by the first MCU to be set at a high level, the NPN type triode Q4 is conducted to control the relay RL1 to be attracted, so that the thermistor NTC1 is short-circuited, the thermistor NTC1 does not work, and stable power supply is realized. The direct current variable frequency motor enters a standby state, and a +15V power supply voltage is provided for the positive end of the control power supply of the IPM module through the protection circuit of the motor driving module, so that the positive end of the control power supply of each switch tube adopts an independent isolated voltage-stabilizing 15V power supply. The upper bridge arm or the lower bridge arm of the IPM module is controlled to be switched on or switched off by the second MCU, namely the lower bridge arm of the IPM module is controlled to be switched on or switched off by the signals of L _ DW, L _ DV and L _ DU, the upper bridge arm of the IPM module is controlled to be switched on or switched off by the signals of H _ DW, H _ DV and H _ DU, and through short circuit between the upper bridge arm and the lower bridge circuit inside can be prevented, so that the direct current variable frequency motor is correctly powered, the direct current variable frequency motor normally operates, the output end of the three-phase motor is matched with the RC absorption circuit, the end of the bootstrap circuit is matched with the RC absorption circuit, and disturbance voltage and disturbance power are effectively inhibited.

The current detection signal amplification module and an operational amplifier arranged in the second MCU jointly form an operational amplifier configuration circuit, the output current of the direct current variable frequency motor flows through the IPM module, is sampled by a resistor R53 to form a voltage signal, is filtered by a capacitor C78 and then flows through a resistor R30 to the inverting input end (AMP 0M end) of the second MCU operational amplifier, the voltage signal (I _ shunt end) flows through a resistor R40 to the non-inverting input end (AM 0P end) of the second MCU operational amplifier, a resistor R33 is connected with the inverting input end (AMP 0M end) of the operational amplifier and the output end (AMP 0O end) of the operational amplifier, the amplification factor is R33/R30+1 times, and a resistor R47 and a resistor R48 respectively correspond to the ground and the VDD5 end and are subjected to voltage division to operational amplifier bias voltage. And U, V, W three-phase output is used as back electromotive force detection signals (EMFU, EMFV, EMFW) after resistance voltage division, and the second MCU collects back electromotive force of EMFU, EMFV, EMFW signals to detect U, V, W three-phase when starting to judge the phase of the DC variable frequency motor, thereby ensuring the starting success rate of the DC variable frequency motor to be 100%.

According to the circuit, a direct-current variable-frequency interference source is inhibited at the source of the direct-current variable-frequency EMC, namely, inhibition analysis is carried out on disturbance voltage and disturbance power interference source parts generated by an IPM module, an RC absorption circuit is matched at the output end of a three-phase motor, and an RC absorption circuit is matched at the end of a bootstrap circuit, so that disturbance voltage and disturbance power are effectively inhibited, three-phase common-mode filter inductors required by the direct-current variable-frequency EMC in the prior art are removed, bipolar filtering at the input end is simplified to single-machine filtering, a top discharge chip is removed while primary common-mode inductors and X capacitors are reduced, the layout of a PCB is simpler, the realization of small-size light weight and cost reduction is facilitated, the reliability is high, and the application range is wide; and the circuit has larger EMC design margin, is beneficial to realizing the design of a direct current variable frequency control platform, is matched with different types of motors or range hood models, can realize development quickly and efficiently only by adjusting software without hardware adjustment, and greatly shortens the research and development period.

All possible combinations of the technical features of the embodiments described above may not be described for the sake of brevity, but should be considered as being within the scope of the present disclosure as long as there is no contradiction between the combinations of the technical features.

The above-mentioned embodiments only express the more specific and detailed embodiments described in the present application, but not be construed as limiting the claims. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the concept of the present application, which falls within the scope of protection of the present application. Therefore, the protection scope of the present patent shall be subject to the appended claims.

Claims

1. The utility model provides a low-cost direct current frequency conversion lampblack absorber EMC circuit, is applied to the lampblack absorber, the lampblack absorber is including the direct current inverter motor who is used for driving the fan, its characterized in that: low-cost direct current frequency conversion lampblack absorber EMC circuit includes first MCU, second MCU, motor drive module and power EMC module, wherein:

the first MCU is used for issuing output parameters of the direct current variable frequency motor to the second MCU, the second MCU controls the direct current variable frequency motor to move according to the received output parameters of the direct current variable frequency motor, and motor running state data are returned to the first MCU;

the W-phase output end, the V-phase output end, the U-phase output end, the W-phase driving positive end, the V-phase driving positive end and the U-phase driving positive end of the upper bridge arm of the IPM module are all grounded through the RC circuit, the W-phase output end, the V-phase output end and the U-phase output end of the IPM module are sequentially connected with the W-phase driving positive end, the V-phase driving positive end and the U-phase driving positive end of the upper bridge arm of the IPM module in a one-to-one correspondence manner through the bootstrap circuit, the W-phase direct-current power supply negative end, the V-phase direct-current power supply negative end and the U-phase direct-current power supply negative end of the IPM module are all grounded, the W-phase logic input end, the V-phase logic input end, the U-phase logic input end, the W-phase logic input end, the upper half bridge V-phase logic input end and the upper half bridge U-phase logic input end of the IPM module are all connected with the second MCU, the W-phase output end, the V-phase driving positive end and the U-phase driving positive end of the IPM module are respectively connected with the CN of the inverter circuit, and the IPM module;

2. The low-cost direct current frequency conversion lampblack absorber EMC circuit of claim 1, characterized in that: the first MCU is communicated with the second MCU through an optical coupling isolation serial port.

3. The low-cost direct current frequency conversion lampblack absorber EMC circuit of claim 1, characterized in that: the power supply voltage of the positive end of the control power supply of the IPM module ranges from +15V to +20V.

4. The low-cost direct current frequency conversion lampblack absorber EMC circuit of claim 1, characterized in that: the motor driving module further comprises a protection circuit, the protection circuit comprises a capacitor C54, a capacitor C55 and a voltage-stabilizing tube D9, the capacitor C54 and the capacitor C55 are connected in parallel, two ends of the capacitor C54 and two ends of the capacitor C55 are respectively connected with two ends of the voltage-stabilizing tube D9, the anode of the voltage-stabilizing tube D9 is grounded, and the cathode of the voltage-stabilizing tube D9 is connected with the positive end of a control power supply of the IPM module.

5. The low-cost direct current frequency conversion lampblack absorber EMC circuit of claim 1, characterized in that: power EMC module includes front end circuit, regulating circuit, common mode inductance TF1 and back-end circuit, wherein:

the adjusting circuit comprises a relay RL1, a diode D9, an NPN type triode Q4, a resistor R31 and a resistor R37, wherein two ends of the resistor R37 are respectively connected with a base electrode and an emitting electrode of the NPN type triode Q4, the emitting electrode of the NPN type triode Q4 is grounded, one end of the resistor R31 is connected with the base electrode of the NPN type triode Q4, the other end of the resistor R31 is connected with the first MCU, a collector electrode of the NPN type triode Q4 and one end of a coil of the relay RL1 are both connected with an anode of the diode D9, a cathode of the diode D9 and the other end of the coil of the relay RL1 are both connected with a positive electrode of a power supply, and a movable contact and a static contact of the relay RL1 are respectively connected with two ends of the thermistor NTC 1;

the rear-end circuit comprises a resistor R89, a resistor R90, an inductor L1, a capacitor C15, a capacitor C21, a capacitor C22, a rectifier bridge DB1, a piezoresistor ZE2, a capacitor C28 and a capacitor C29, wherein the resistor R89 and the resistor R90 are connected in series at two ends of the capacitor C21, one end of the capacitor C21 is respectively connected with a first pin of the common-mode inductor TF1 and one end of the inductor L1, one ends of the capacitor C15 and the capacitor C22 are connected in a common ground mode, the other end of the capacitor C15 is respectively connected with the other end of the inductor L1 and a first input end of the rectifier bridge DB1, the other ends of the capacitor C21 and the capacitor C22 and a second input end of the rectifier bridge DB1 are connected with a fourth pin of the common-mode inductor TF1, one end of the resistor ZE2 is respectively connected with a positive output end of the rectifier bridge DB1 and a positive electrode of the electrolytic capacitor C59, the other end of the rectifier bridge DB1 is connected with a negative electrode output end of the rectifier bridge DB1 and the other end of the rectifier bridge DB 29.

6. The low-cost direct current frequency conversion lampblack absorber EMC circuit of claim 1, characterized in that: the motor driving module further comprises a resistor R53, a resistor R56 and a capacitor C45, wherein the W-phase direct-current power supply negative end, the V-phase direct-current power supply negative end and the U-phase direct-current power supply negative end of the IPM module are connected with each other, the W-phase direct-current power supply negative end of the IPM module is grounded through the resistor R53, and the U-phase direct-current power supply negative end of the IPM module is grounded through the resistor R56 and the capacitor C45 in sequence.

7. The low-cost direct current frequency conversion lampblack absorber EMC circuit of claim 6, characterized in that: low-cost direct current frequency conversion lampblack absorber EMC circuit still includes current detection signal amplification module, current detection signal amplification module includes resistance R30, resistance R33, resistance R40, resistance R47, resistance R48, electric capacity C78 and operational amplifier, wherein:

the utility model discloses a IPM module, including IPM module, resistance R33, resistance R30, electric capacity C78, resistance R40 and resistance R47 connect gradually, just resistance R30 and electric capacity C78's common terminal ground connection, electric capacity C78 and resistance R40's common terminal with the W looks DC power negative terminal of IPM module is connected, resistance R33 and resistance R30's common terminal with operational amplifier's inverting input end is connected, resistance R33's the other end with operational amplifier's output is connected, resistance R40 and resistance R47's common terminal respectively with operational amplifier's non inverting input end with resistance R48's one end is connected, resistance R47's the other end ground connection, resistance R48's another termination +5V voltage, resistance R47 and resistance R48 form 2.5V offset voltage.

8. The low-cost direct current frequency conversion lampblack absorber EMC circuit of claim 7, characterized in that: the amplification factor of the operational amplifier is 11 times.

9. The low-cost direct current frequency conversion lampblack absorber EMC circuit of claim 1, characterized in that: low-cost direct current frequency conversion lampblack absorber EMC circuit still includes counter electromotive force detection module, counter electromotive force detection module includes resistance R23, resistance R24, resistance R25, resistance R34, resistance R35, resistance R36, resistance R41, resistance R42, resistance R43, resistance R49, resistance R50, resistance R51, electric capacity C35, electric capacity C36 and electric capacity C37, wherein:

the resistor R23, the resistor R24 and the resistor R25 are sequentially connected, one end of the resistor R49 and one end of the capacitor C35 are both connected with the common end of the resistor R23 and the resistor R24, and the other ends are grounded;

the resistor R41, the resistor R42 and the resistor R43 are sequentially connected, one end of the resistor R51 and one end of the capacitor C37 are connected with the common end of the resistor R41 and the common end of the resistor R42, and the other ends of the resistor R51 and the common end of the capacitor C37 are grounded;

one ends, far away from the connected resistors, of the resistor R25, the resistor R36 and the resistor R43 are further respectively connected with the U-phase output end, the V-phase output end and the W-phase output end of the IPM module in a one-to-one correspondence mode, and one ends, far away from the connected resistors, of the resistor R23, the resistor R34 and the resistor R41 are correspondingly connected with the AD sampling interface of the second MCU.

10. The low-cost direct current frequency conversion lampblack absorber EMC circuit of claim 1, characterized in that: the IPM module adopts a 600V 6A IGBT driving chip.