CN115800827B

CN115800827B - Low-cost direct-current variable-frequency range hood EMC circuit

Info

Publication number: CN115800827B
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: 2023-11-07
Anticipated expiration: 2042-11-04
Also published as: CN115800827A

Abstract

The invention discloses an EMC circuit of a low-cost direct-current variable-frequency range hood, which comprises a first MCU, a second MCU, a motor driving module and a power EMC module, wherein the first MCU is used for transmitting output parameters of a direct-current variable-frequency motor to the second MCU, and the second MCU controls the direct-current variable-frequency motor to move according to the received output parameters 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, and is used for driving the direct-current variable frequency motor; the power EMC module is used for supplying power and realizing the charging of the electrolytic capacitor C59 when the power is on to prevent spark. The circuit can effectively inhibit disturbance voltage and disturbance power interference from the source, simplifies the power supply end into single-stage filtering, is favorable for realizing miniaturization and light weight, reduces cost, shortens research and development period, and has high reliability and wide application range.

Description

Low-cost direct-current variable-frequency range hood EMC circuit

Technical Field

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

Background

In recent years, the use of direct-current frequency conversion control technology on household appliances has become mature, and direct-current frequency conversion range hoods have become the mainstream of 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 a high-frequency signal is output by an MCU to control the switching tube at a high-voltage end and the switching tube at a low-voltage end in the power module to be sequentially switched on and off so as to realize the driving of three windings of the motor.

The direct-current voltage is regulated by the MCU to control the motor winding to generate a FOC control mode similar to sine wave current, and the direct-current power supply can generate serious disturbance voltage and disturbance power EMC interference under the condition of high-frequency switching, for example, a direct-current variable-frequency range hood usually uses a high-frequency 13-18K carrier frequency control power device to drive a direct-current variable-frequency motor. The 220V alternating current power supply is rectified by the rectifier bridge and then is about 310V direct current voltage, the three-phase high-voltage half-bridge circuit is controlled to be sequentially conducted up and down by the MCU to enable the motor winding to generate a FOC control mode similar to sine wave current, a serious working mode interference source and a differential mode interference source can be generated under the condition of a direct current high-frequency switch, and interference to the power supply circuit under the working state of the direct current variable frequency plate can be intuitively observed through the disturbance voltage and disturbance power tester. The main interference frequency bands of the frequency conversion range hood are 20-26MHz disturbance voltage frequency bands and 30-40MHz disturbance voltage frequency bands.

The EMC circuit of the conventional direct-current variable-frequency range hood controller generally adopts a mode that a first-stage large-capacity X capacitor and a common-mode inductor are connected in series and a first-stage small-capacity X capacitor processing mode inductor are connected in series in two stages, so that low-frequency disturbance voltage interference and partial high-frequency interference are restrained. And a three-phase common mode inductor is arranged at the output end of the motor to inhibit high-frequency disturbance. Usually, the EMC test allowance of the whole machine is still lower by adopting the two measures. And a special EMC inhibitor is added at the power supply end by some manufacturers to improve the test allowance of EMC. The mode of connecting the two stages of X capacitors and the common mode inductor in series is to connect a top discharge chip in parallel at the X capacitor end in order to ensure that the safety voltage lower than 36V is achieved in the power-off 1S at the top of alternating current by the safety plug and the national standard standby power consumption required by design is achieved. In this way, more components are added, the layout of the PCB needs larger size, the cost of the components is increased, and the common-mode inductance generates larger heat under the condition of full load, so that the stability of the control board is also affected to a certain extent. Compared with the control mode of the traditional alternating current motor, the existing direct current frequency conversion technology is quite complex, and has higher requirements for designers.

In the scheme, the voltage mutation of DV/Dt in the switching process is reduced, the effect is relatively limited, disturbance voltage and disturbance power are required to be restrained through matching of a power end bipolar filter circuit, the size and cost of a controller are increased, the price of a direct-current variable-frequency product is high, the EMC allowance is small, and even if the same control board is slightly different in air channels and motors of different range hoods, the matching is required to be debugged again, and the research and development are time-consuming and labor-consuming. Therefore, it is particularly important how to effectively inhibit the DV/Dt voltage mutation of the IPM module of the DC variable frequency controller in the bridge arm switching process.

Disclosure of Invention

Aiming at the problems, the invention provides the low-cost direct-current variable-frequency range hood EMC circuit which can efficiently inhibit disturbance voltage and disturbance power interference from the source, simplifies the power supply end into single-stage filtering, is beneficial to realizing miniaturization and light weight, reduces cost, shortens research and development period, has high reliability and wide application range.

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

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

The first MCU is used for transmitting output parameters of the direct-current variable-frequency motor to the second MCU, and 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 two bootstrap capacitors are connected in parallel:

the two ends of the fuse F2 are respectively connected with the positive electrode of the electrolytic capacitor C59 and one end of the capacitor C60, the negative electrode of the electrolytic capacitor C59 and the other end of the capacitor C60 are grounded together, 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 upper bridge arm W-phase driving positive end, the upper bridge arm V-phase driving positive end and the upper bridge arm U-phase driving positive end 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 upper bridge arm W-phase driving positive end, the upper bridge arm V-phase driving positive end and the upper bridge arm U-phase driving positive end 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 grounded, the lower bridge arm W-phase logic input end, the lower bridge arm V-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 connected with a second MCU, the upper bridge V-phase logic input end or lower bridge U-phase logic input end of the IPM module is controlled through the second MCU to realize the connection or disconnection of the IPM module, the lower bridge arm of the IPM module is grounded in a one-to-one correspondence manner, and the lower bridge arm of the IPM module is connected with the three-phase output ends of the IPM module through the control power supply module and the corresponding to the three-phase output ends of the IPM module, the output end is connected with the three-phase output end of the IPM output end, and the output end of the IPM module is connected with the output power output terminal;

And the power EMC module is used for supplying power and realizing the charging of the electrolytic capacitor C59 when the power is on to prevent spark generation.

Preferably, the first MCU communicates with the second MCU through an optocoupler isolation serial port.

Preferably, the power supply voltage at the positive end 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 stabilizing tube D9, the capacitor C54 and the capacitor C55 are connected in parallel, two ends of the protection circuit are respectively connected with two ends of the voltage stabilizing tube D9, the positive electrode of the voltage stabilizing tube D9 is grounded, and the negative electrode of the protection circuit is connected with the positive end of a 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:

the first pin and the second pin of the common mode inductor TF1 form a first winding, and the third pin and the 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 regulating 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 emitter electrode of the NPN type triode Q4, the emitter 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 a first MCU, one ends of a collector electrode of the NPN type triode Q4 and a coil of the relay RL1 are both connected with an anode of the diode D9, the 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 movable contact and a fixed contact of the relay RL1 are respectively connected with two ends of the thermistor NTC 1;

the back-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 with the 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 grounded, the other end of the capacitor C15 is respectively connected with the other end of the inductor L1 and the first input end of the rectifier bridge DB1, the other ends of the capacitor C21 and the capacitor C22 and the second input end of the rectifier bridge DB1 are respectively connected with a fourth pin of the common mode inductor TF1, one end of the piezoresistor ZE2 is respectively connected with the positive output end of the rectifier bridge DB1 and the positive electrode of the electrolytic capacitor C59, the other end of the piezoresistor ZE2 is grounded with the negative output end of the rectifier bridge DB1 and one end of the capacitor C28, one end of the capacitor C29 is connected with the positive output end of the rectifier bridge DB1, and the other ends 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 negative W-phase dc power supply terminal, the negative V-phase dc power supply terminal and the negative U-phase dc power supply terminal of the IPM module are connected to each other, and the negative W-phase dc power supply terminal of the IPM module is grounded through the resistor R53, and the negative U-phase dc power supply terminal of the IPM module is grounded through the resistor R56 and the capacitor C45 in sequence.

Preferably, the low-cost direct-current variable-frequency range hood EMC circuit further comprises a current detection signal amplification module, wherein 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, and the current detection signal amplification module comprises:

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 the 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 resistor R47 is 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 factor of 11.

Preferably, the low-cost direct-current variable frequency range hood EMC circuit further comprises a back electromotive force detection module, wherein the back 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, and the back electromotive force detection module comprises:

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 connected with a common end of the resistor R23 and the resistor R24, and the other end is 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 connected with a common end of the resistor R34 and the resistor R35, and the other end is 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 a common end of the resistor R41 and the resistor R42, and the other end is grounded;

and one ends of the resistor R25, the resistor R36 and the resistor R43, which are far away from the connected resistor, are correspondingly connected with the U-phase output end, the V-phase output end and the W-phase output end of the IPM module one by one, and one ends of the resistor R23, the resistor R34 and the resistor R41, which are far away from the connected resistor, are correspondingly connected with the AD sampling interface of the second MCU.

Preferably, the IPM module employs 600v 6a IGBT driver chips.

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

1) The circuit suppresses the direct-current variable-frequency interference source at the source of the direct-current variable-frequency EMC, namely, the disturbance voltage and disturbance power generated by the IPM module interfere with the source part to carry out the suppression analysis, the RC absorption circuit is matched at the output end of the three-phase motor, the RC absorption circuit is matched at the bootstrap circuit end, the disturbance voltage and the disturbance power are effectively suppressed, the three-phase common-mode filter inductance required by the direct-current variable-frequency EMC in the prior art is removed, the input-end bipolar filter is simplified to be single-machine filter, the first-stage common-mode inductance and the X capacitance are reduced, and meanwhile, the top discharge chip is removed, so that the PCB layout is simpler, the realization of small-size light weight and the cost reduction are facilitated, the reliability is high, and the application range is wide;

2) The circuit EMC design allowance is larger, the direct-current variable-frequency control platform design is facilitated, only software is adjusted when different types of motors or range hood types are matched, development can be rapidly and efficiently realized without hardware adjustment, and the research and development period is greatly shortened.

Drawings

Fig. 1 is a schematic diagram of the structure of the EMC circuit of the low-cost dc variable frequency range hood of the present invention;

FIG. 2 is a circuit diagram of a motor drive module according to the present application;

FIG. 3 is a circuit diagram of the power EMC module of the present application;

FIG. 4 is a circuit diagram of the current sense signal amplifying module of the present application;

fig. 5 is a circuit diagram of the back emf detection module of the present application;

FIG. 6 is a graph of the disturbance voltage detection result of the present application;

FIG. 7 is a graph of the disturbance power detection result of the present application;

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

FIG. 9 is a graph of the disturbance power detection results of the prior art.

Detailed Description

The following description of the embodiments of the present application will be made clearly and completely with reference to the accompanying drawings, in which it is apparent that the embodiments described are only some embodiments of the present application, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the application without making any inventive effort, are intended to be within the scope of the 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 herein in the description of the application 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 variable frequency range hood EMC circuit is applied to a range hood, the range hood comprises a direct-current variable frequency motor for driving a fan, the low-cost direct-current variable frequency range hood EMC circuit comprises a first MCU, a second MCU, a motor driving module and a power EMC module, wherein:

The range hood can be any structure in the prior art, for example, mainly comprises a direct-current variable-frequency motor, a fan and a man-machine board, and a circuit generally adopts a single 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 board or designed in a split type. The main control chip (first MCU) is used for overall logic control, and is interacted with the man-machine board through serial communication, key information and setting state of the man-machine board are obtained, and running state data of the first MCU are sent to the man-machine board, and the man-machine board is displayed to a user through an LED screen or an LED lamp. The first MCU is communicated with the second MCU through an optocoupler isolation serial port, output parameters required by the direct-current variable-frequency motor are sent to the second MCU, and the second MCU sends motor running state data back to the first MCU. It should be noted that, usually, the lampblack absorber is commonly installed and is used the illumination by 6-10W's LED lamp, and the LED lamp passes through first MCU control switch, if be that side-draught lampblack absorber is usually realized turning over the board by first MCU control electric putter, and the specific quantity of LED lamp and electric putter can be adjusted according to actual demand.

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 quantity is 24 cubes. In order to realize 380W maximum input power module, an IPM module of 600V 6A IGBT is adopted to drive the direct-current variable-frequency motor, for example, the type of the IPM module is XNS06S72F6, in order to ensure effective heat dissipation, the IPM module is packaged by DIP-25, and the effective heat dissipation is realized by attaching larger heat dissipation fins to a metal cover of a control panel of the range hood through heat-conducting silica gel. In the figure, SGND is a non-isolated ground, and AGND is a power ground.

In one embodiment, the first MCU communicates with the second MCU through an optocoupler isolation serial port.

In one embodiment, the supply voltage at 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 stabilizing tube D9, the capacitor C54 and the capacitor C55 are connected in parallel, two ends of the protection circuit are respectively connected with two ends of the voltage stabilizing tube D9, an anode of the voltage stabilizing tube D9 is grounded, and a cathode of the protection circuit is connected with a positive end 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 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 lower bridge arm of the IPM module is grounded by reference to the ground end (comprising pins 9 and 16), and is powered by the positive end (comprising pins 8 and 13) of the control power supply of the IPM module, and an electric voltage stabilizing tube D9 in the protection circuit is a voltage stabilizing diode for protection, so that the damage of the IPM module is avoided. The positive end of the control power supply of the IPM module is an internal driving power supply end, the maximum power supply voltage is +20v, and the power supply voltage is usually +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 (corresponding to 12 th, 11 th, 10 th, 7 th, 6 th and 5 th pins in sequence) of the IPM module are all connected with the second MCU, a resistor of 20-47 omega is usually connected in series between the second MCU and the input end of the IPM module, and meanwhile, a ceramic chip capacitor of 100pF is placed at the input end of the IPM module to reduce signal interference, and the on/off of the upper bridge arm or the lower bridge arm of the IPM module is realized through the control of the second MCU. Specifically, one end of the resistor R58, the resistor R59 and the resistor R62 is sequentially and correspondingly connected with the 12 th pin, the 11 th pin and the 10 th pin of the IPM module, the other end of the resistor R62 is correspondingly connected with the second MCU, one end of the capacitor C40, the capacitor C41 and one end of the capacitor C42 are commonly grounded, the other end of the resistor R58, the resistor R59 and the resistor R62 is sequentially and correspondingly connected with the 12 th pin, the 11 th pin and the 10 th pin of the IPM module, the second MCU is used for realizing the on or off of the lower bridge arm of the IPM module by controlling the 12 th pin, the 11 th pin and the 10 th pin of the IPM module, one end of the resistor R63, the resistor R64 and the resistor R65 are sequentially and correspondingly connected with the 7 th pin, the 6 th pin and the 5 th pin of the IPM module, the other end of the capacitor C50, the capacitor C51 and one end of the capacitor C52 are commonly grounded, and the other end of the resistor R52 is sequentially and correspondingly connected with the 7 th pin, the 6 th pin and the 5 th pin of the IPM module, and the second MCU is used for realizing the on or off of the IPM module by controlling the 7 th pin, the 6 th pin and the 5 th pin of the IPM module.

The two ends of the fuse F2 are respectively connected with the positive electrode of the electrolytic capacitor C59 and one end of the capacitor C60, the negative electrode of the electrolytic capacitor C59 and the other end of the capacitor C60 are grounded, 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. The 220V alternating current input by the range hood is rectified by the rectifier bridge to obtain 310V direct current voltage VDC. An electrolytic capacitor C59 with 450V 330UF is arranged at the front end of the VDC and used 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 authentication of whole machine software can be avoided. A CBB capacitor C60 with 630V 10nF is placed at the rear end of the fuse F2, so that partial differential mode interference at the edge end of the direct-current variable-frequency motor can be absorbed, and burrs of the VDC power supply end in the working state can be reduced.

The negative end of the W-phase direct current power supply, the negative end of the V-phase direct current power supply and the negative end of the U-phase direct current power supply (pins 18, 19 and 20 in sequence) of the IPM module are mutually connected, the negative end of the W-phase direct current power supply of the IPM module is grounded through a resistor R53, and the negative end of the U-phase direct current power supply 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 upper bridge arm W phase driving positive end, the upper bridge arm V phase driving positive end and the upper bridge arm U phase driving positive end (21, 22, 23, 4, 3 and 2 pins in sequence) of the IPM module are grounded through RC circuits, specifically, a capacitor C53, a capacitor C56, a capacitor C58, a capacitor C61, a capacitor C62 and a capacitor C63 are bootstrap 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 nd pin of the IPM module, the capacitor C58 and the capacitor C61 are connected in parallel, two ends of the capacitor C58 and the capacitor C61 are respectively connected with the 3 rd pin and the 22 nd pin of the IPM module, two ends of the capacitor C62 and the capacitor C63 are respectively connected with the 4 nd pin and the 21 nd pin of the IPM module, one ends of the capacitor C90, the capacitor C91 and the capacitor C92 are respectively correspondingly connected with the 2 nd pin, the 3 rd pin and the 4 th pin of the IPM module in sequence, the other ends of the capacitor C16, the capacitor C85 and the capacitor C86 are connected with the corresponding pins of the 23 th pin and the resistor R32.

The three wiring terminals of the first socket CN3 are respectively connected with the W-phase output end, the V-phase output end and the U-phase output end of the IPM module in a one-to-one correspondence manner and are used for being correspondingly connected with the three-phase input end of the direct-current variable-frequency motor, namely, the three-phase input end of the direct-current variable-frequency motor is correspondingly connected with the W-phase output end, the V-phase output end and the U-phase output end of the IPM module in an in-phase manner.

In one embodiment, the power EMC module includes 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 actual measurement of the whole machine can work normally under the surge L-N2KV, L-ground and N-ground 4KV values, and an X capacitor C20 of 0.68uF is selected. And then to the back-end circuit via the SQ1918-15mH common-mode inductance TF 1. The back-end circuit capacitor discharge resistor is connected in series by using two 1206/270K resistors (resistor R89 and resistor R90), so that the safety voltage lower than 36V and the standby power consumption of the whole machine smaller than 0.5W can be achieved when the safety plug AC1 is discharged in the power-off 1S of the top end of alternating current. And a silicon steel sheet inductor L1 with EI2817 of about 3.0mH is placed at the rear end of the common mode inductor TF1, so that the harmonic current of the whole machine can be ensured to meet national standard requirements.

A Y1 capacitor (capacitor C15 and capacitor C22) of 22nF is respectively arranged at the front end L-earth and the front end N-earth of the rectifier bridge, a Y1 capacitor (capacitor C28) of 22nF is arranged between the earth and the rear end earth of the rectifier bridge, and the dead point of the earth and the dead point of the rear end of the rectifier bridge are connected across the Y capacitor. The reasonable design of the Y capacitor is very effective for suppressing the low-frequency disturbance voltage in the frequency range of 1-10 MHz. After the disturbance voltage and the disturbance power are effectively restrained by the EMC source of the IPM module, an EMC circuit at the input end of the power supply can be effectively simplified, only single-stage filtering is used, and the method is beneficial to improving the disturbance voltage and the disturbance power restraining effect and reducing the cost and the volume.

In an embodiment, the motor driving module further includes a resistor R53, a resistor R56, and a capacitor C45, the negative terminals of the W-phase dc power supply, the negative terminals of the V-phase dc power supply, and the negative terminals of the U-phase dc power supply of the IPM module are connected to each other, and the negative terminals of the W-phase dc power supply of the IPM module are grounded through the resistor R53, and the negative terminals of the U-phase dc power supply of the IPM module are sequentially grounded through the resistor R56 and the capacitor C45.

In an embodiment, the low-cost direct current variable frequency range hood EMC circuit further includes a current detection signal amplification module, wherein 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, and the current detection signal amplification module includes:

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

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

In an embodiment, the low-cost dc variable frequency range hood EMC circuit further includes a back electromotive force detection module, where the back 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:

The lampblack absorber has upwind/downwind starting state under special conditions, and needs to detect back electromotive force of output U, V, W three phases, and detect the state of the direct-current variable-frequency motor before starting so as to ensure that the direct-current variable-frequency motor is started quickly and successfully. The U, V, W three-phase interface voltage of the IPM module is divided by the resistor, and then the signal is sampled by the AD sampling interface of the second MCU, so that the forward and reverse rotation states and the relative phases of the direct-current variable-frequency motor can be judged.

In one embodiment, the IPM module employs 600v 6a IGBT driver chips.

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 current waveform is reflected to the fact that the IPM module is turned on for the U-phase upper bridge arm, turned off for the lower bridge arm, turned off for the V-phase lower bridge arm, turned off for the upper bridge arm … …, the bridge arms are turned on in turn, and the duty ratio is adjusted in real time according to different load outputs. The switch of the bridge arm is always 310V high voltage of VDC and the ground, and the direct current frequency conversion has larger DV/Dt voltage abrupt change interference, and especially the abrupt change is prominent in the phase switching process. The disturbance voltage is reflected to a disturbance source with disturbance voltage of 10-30 MHz in the whole wave band. As shown in fig. 8 and 9, when EMC in the prior art uses only simple bipolar filtering, the actual measurement effect of the disturbance voltage is very poor, the direct-current variable-frequency motor is very obvious in 14 mhz band exceeding, and the actual measurement of the disturbance power is severely exceeding 30-60 mhz.

According to the application, the RC absorption circuit is added between the three phases (21 st, 22 nd and 23 rd pins) of the IPM module output U, V, W and the ground, so that voltage abrupt change in the switching process of the IGBT in the IPM module, particularly voltage abrupt 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 power input end, the resistor R32 with the ohm of 0-5.1 is connected in series between the U, V, W three-phase common point and the ground, so that 15-30 MHz disturbance voltage can be effectively restrained.

In order to overcome high-frequency disturbance generated by the IPM module in the 4 th, 3 rd and 2 nd pin bootstrap circuits in the phase switching process, the relative margin of disturbance power is improved, and the RC absorption circuit is added at the front end (4 th, 3 nd 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 restrained.

In summary, an RC absorption circuit is added at the output end of the IPM module, the disturbance voltage of the direct-current variable-frequency range hood controller can be effectively inhibited under the condition that only a single-stage filter circuit is used at the power supply end, the actual disturbance voltage allowance 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 actual disturbance power allowance is more than 10 DB.

Working principle:

in the power-on process, AC220V voltage is accessed through a power plug AC1, and the electrolytic capacitor C59 is charged through a fuse F1, a thermistor NTC1, a common mode inductor TF1, an inductor L1 (harmonic inductance) and a rectifier bridge DB1, wherein the thermistor NTC1 is mainly used for preventing potential safety hazards such as ignition caused by spark generated by large current in the plug power-on process. Before the direct-current variable frequency motor is started, as 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 EMC module is set to be high level, the NPN triode Q4 is conducted to control the relay RL1 to be attracted so as to short-circuit the thermistor NTC1, and the thermistor NTC1 does not work, so that stable power supply is realized. The direct-current variable frequency motor enters a standby state, and a protection circuit of the motor driving module provides +15V power supply voltage for the positive end of the control power supply of the IPM module, so that the positive end of the control power supply of each switching tube adopts an independent isolated voltage-stabilized 15V power supply. The on or off of the upper bridge arm or the lower bridge arm of the IPM module is realized through the control of the second MCU, namely, the on or off of the lower bridge arm of the IPM module is controlled through the L_DW, L_DV and L_DU signals, the on or off of the upper bridge arm of the IPM module is controlled through the H_DW, H_DV and H_DU signals, and the through short circuit of the upper bridge arm and the lower bridge circuit inside can be prevented, so that the correct power supply to the direct-current variable-frequency motor is realized, the normal operation of the direct-current variable-frequency motor is realized, the RC absorption circuit is matched through the output end of the three-phase motor, and the RC absorption circuit is matched at the bootstrap circuit end, thereby effectively inhibiting the disturbance voltage and the disturbance power.

The current detection signal amplifying module and an operational amplifier built in the second MCU jointly form an operational amplifier configuration circuit, the output current of the direct-current variable-frequency motor is sampled through a resistor R53 through an IPM module to form a voltage signal, the voltage signal is filtered through a capacitor C78 and then is sent to an inverting input end (AMP 0M end) of the operational amplifier of the second MCU through a resistor R30, the voltage signal (I_shot end) is sent to a non-inverting input end (AM 0P end) of the operational amplifier of the second MCU through a resistor R40, a resistor R33 is connected with the inverting input end (AMP 0M end) of the operational amplifier and an output end (AMP 0O end) of the operational amplifier, the amplification factor is R33/R30+1, and a resistor R47 and a resistor R48 are respectively correspondingly grounded and a VDD5 end are divided to be operational amplifier bias voltages. And U, V, W three-phase output is used as a reverse electromotive force detection signal (EMFU, EMFV, EMFW) after being divided by resistors, and the second MCU acquires EMFU, EMFV, EMFW signals to detect the counter electromotive force of U, V, W three phases during starting so as to judge the phase of the direct-current variable-frequency motor, thereby ensuring that the starting success rate of the direct-current variable-frequency motor is 100%.

The circuit suppresses the direct-current variable-frequency interference source at the source of the direct-current variable-frequency EMC, namely, the disturbance voltage and disturbance power generated by the IPM module interfere with the source part to carry out the suppression analysis, the RC absorption circuit is matched at the output end of the three-phase motor, the RC absorption circuit is matched at the bootstrap circuit end, the disturbance voltage and the disturbance power are effectively suppressed, the three-phase common-mode filter inductance required by the direct-current variable-frequency EMC in the prior art is removed, the input-end bipolar filter is simplified to be single-machine filter, the first-stage common-mode inductance and the X capacitance are reduced, and meanwhile, the top discharge chip is removed, so that the PCB layout is simpler, the realization of small-size light weight and the cost reduction are facilitated, the reliability is high, and the application range is wide; the EMC design allowance of the circuit is larger, the direct-current variable-frequency control platform design is facilitated, only software is adjusted when the direct-current variable-frequency control platform is matched with different types of motors or range hood types, development can be rapidly and efficiently realized without hardware adjustment, and the research and development period is greatly shortened.

The technical features of the above-described embodiments may be arbitrarily combined, and all possible combinations of the technical features in the above-described embodiments are not described for brevity of description, however, as long as there is no contradiction between the combinations of the technical features, they should be considered as the scope of the description.

The above-described embodiments represent only the more specific and detailed embodiments of the present application, but are not to be construed as limiting the claims. It should be noted that it will be apparent to those skilled in the art that several variations and modifications can be made without departing from the spirit of the application, which are all within the scope of the application. Accordingly, the scope of protection of the present application is to be determined by the appended claims.

Claims

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

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 bootstrap capacitors are arranged in the same circuit:

the W-phase output end, the V-phase output end, the U-phase output end, the upper bridge arm W-phase driving positive end, the upper bridge arm V-phase driving positive end and the upper bridge arm U-phase driving positive end of the IPM module are 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 upper bridge arm W-phase driving positive end, the upper bridge arm V-phase driving positive end and the upper bridge arm U-phase driving positive end of the IPM module in one-to-one correspondence through the bootstrap circuit, 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 grounded, 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 of the IPM module are connected with the second MCU in turn, the upper bridge or lower bridge arm W-phase logic input end of the IPM module is correspondingly connected with the MCU through the second control, and the IPM module is correspondingly connected with the three-phase power supply end of the MCU module through the MCU, and the three-phase power supply end is correspondingly connected with the power supply end of the MCU module through the power supply terminal, the power supply terminal is correspondingly connected with the power supply terminal of the MCU module, and the power terminal is connected with the power supply terminal through the power terminal;

The bootstrap circuits are three, and bootstrap capacitors of all the bootstrap circuits comprise a capacitor C53, a capacitor C56, a capacitor C58, a capacitor C61, a capacitor C62 and a capacitor C63, wherein:

the capacitor C53 and the capacitor C56 are connected in parallel, the two ends of the capacitor C53 and the capacitor C56 are respectively connected with the positive driving end and the output end of the U phase of the upper bridge arm of the IPM module, the capacitor C58 and the capacitor C61 are connected in parallel, the two ends of the capacitor C58 and the capacitor C61 are respectively connected with the positive driving end and the output end of the V phase of the upper bridge arm of the IPM module, and the capacitor C62 and the capacitor C63 are connected in parallel, and the two ends of the capacitor C62 and the capacitor C63 are respectively connected with the positive driving end and the output end of the W phase of the upper bridge arm of the IPM module;

the number of the RC circuits is six, and all the RC circuits comprise a capacitor C90, a capacitor C91, a capacitor C92, a resistor R76, a capacitor C16, a capacitor C85, a capacitor C86 and a resistor R32, wherein:

one end of the capacitor C90, the capacitor C91 and the capacitor C92 are sequentially and correspondingly connected with the upper bridge arm U-phase driving positive end, the upper bridge arm V-phase driving positive end and the upper bridge arm W-phase driving positive end of the IPM module, the other end of the capacitor C16, the capacitor C85 and the capacitor C86 are sequentially and correspondingly connected with the U-phase output end, the V-phase output end and the W-phase output end of the IPM module, and the other end of the capacitor C16, the capacitor C85 and the W-phase output end are commonly grounded through the resistor R32;

The power EMC module is used for supplying power and realizing the charging of the electrolytic capacitor C59 to prevent spark;

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

the regulating 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 emitter electrode of the NPN triode Q4, the emitter 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 the first MCU, 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 movable contact and a fixed contact of the relay RL1 are respectively connected with two ends of the thermistor NTC 1;

The back-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 with 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 grounded, the other end of the capacitor C15 is respectively connected with the other end of the inductor L1 and the first input end of the rectifier bridge DB1, the other ends of the capacitor C21 and the capacitor C22, the second input end of the rectifier bridge DB1 are respectively connected with a fourth pin of the common mode inductor TF1, one end of the piezoresistor ZE2 is respectively connected with the positive output end of the rectifier bridge DB1 and the positive electrode of the electrolytic capacitor C59, the other end of the piezoresistor ZE2 is grounded with the negative output end of the rectifier bridge DB1, the other end of the capacitor C15 is connected with the first input end of the rectifier bridge DB1, and the other end of the capacitor C29 is connected with the common mode inductor DB 28.

2. The direct current variable frequency range hood EMC circuit of claim 1, wherein: the first MCU is communicated with the second MCU through an optocoupler isolation serial port.

3. The direct current variable frequency range hood EMC circuit of claim 1, wherein: the power supply voltage of the positive end of the control power supply of the IPM module is +15V to +20V.

4. The direct current variable frequency range hood EMC circuit of claim 1, wherein: 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 are respectively connected with two ends of the voltage stabilizing tube D9, the positive electrode of the voltage stabilizing tube D9 is grounded, and the negative electrode of the voltage stabilizing tube D9 is connected with the positive end of a control power supply of the IPM module.

5. The direct current variable frequency range hood EMC circuit of claim 1, wherein: the motor driving module further comprises a resistor R53, a resistor R56 and a capacitor C45, wherein the negative ends of the W-phase direct current power supply, the negative ends of the V-phase direct current power supply and the negative ends of the U-phase direct current power supply of the IPM module are mutually connected, the negative ends of the W-phase direct current power supply of the IPM module are grounded through the resistor R53, and the negative ends of the U-phase direct current power supply of the IPM module are sequentially grounded through the resistor R56 and the capacitor C45.

6. The direct current variable frequency range hood EMC circuit of claim 5, wherein: the direct-current variable-frequency range hood EMC circuit further comprises a current detection signal amplification module, wherein 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, and the current detection signal amplification module comprises:

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 the 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 ends of the resistor R40 and 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.

7. The direct current variable frequency range hood EMC circuit of claim 6, wherein: the amplification factor of the operational amplifier is 11 times.

8. The direct current variable frequency range hood EMC circuit of claim 1, wherein: the direct current variable frequency lampblack absorber EMC circuit still includes back electromotive force detection module, back 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 connected with the common end of the resistor R23 and the resistor R24, and the other end is 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 connected with a common end of the resistor R34 and the resistor R35, and the other end of the resistor R50 and the capacitor C36 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 resistor R42, and the other end is grounded;

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

9. The direct current variable frequency range hood EMC circuit of claim 1, wherein: the IPM module adopts 600V/6A, and an IGBT driving chip.