CN107093976B - Universal variable-frequency speed regulation system based on DSP - Google Patents
Universal variable-frequency speed regulation system based on DSP Download PDFInfo
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- CN107093976B CN107093976B CN201710524714.6A CN201710524714A CN107093976B CN 107093976 B CN107093976 B CN 107093976B CN 201710524714 A CN201710524714 A CN 201710524714A CN 107093976 B CN107093976 B CN 107093976B
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02P—CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
- H02P27/00—Arrangements or methods for the control of AC motors characterised by the kind of supply voltage
- H02P27/04—Arrangements or methods for the control of AC motors characterised by the kind of supply voltage using variable-frequency supply voltage, e.g. inverter or converter supply voltage
- H02P27/06—Arrangements or methods for the control of AC motors characterised by the kind of supply voltage using variable-frequency supply voltage, e.g. inverter or converter supply voltage using dc to ac converters or inverters
- H02P27/08—Arrangements or methods for the control of AC motors characterised by the kind of supply voltage using variable-frequency supply voltage, e.g. inverter or converter supply voltage using dc to ac converters or inverters with pulse width modulation
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H7/00—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions
- H02H7/10—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions for converters; for rectifiers
- H02H7/12—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions for converters; for rectifiers for static converters or rectifiers
- H02H7/1216—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions for converters; for rectifiers for static converters or rectifiers for AC-AC converters
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02P—CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
- H02P1/00—Arrangements for starting electric motors or dynamo-electric converters
- H02P1/16—Arrangements for starting electric motors or dynamo-electric converters for starting dynamo-electric motors or dynamo-electric converters
- H02P1/26—Arrangements for starting electric motors or dynamo-electric converters for starting dynamo-electric motors or dynamo-electric converters for starting an individual polyphase induction motor
Abstract
The DSP-based universal variable frequency speed regulation system comprises a main circuit, a control circuit and a protection circuit. The main circuit is composed of three parts of a three-phase uncontrolled rectifying link, a filtering link and an inversion link. The direct current voltage output by the rectifier bridge is not stable enough and has harmonic waves, so that the bus voltage is more stable for filtering harmonic wave components in the direct current voltage, and two ends of the direct current bus are connected with a capacitor C3 in parallel. The filtered DC bus voltage can pass through the three-phase controllable inverter bridge to obtain the needed three-phase alternating current, and the driving motor M operates according to the requirement. The universal variable frequency speed regulating system based on the DSP can realize large torque starting of the asynchronous motor, can realize wide-range variable frequency speed regulation of the asynchronous motor, and is the optimal operation mode of the asynchronous motor at present. Compared with the direct full-voltage starting and low-voltage soft starting methods of asynchronous motors, the method has obvious technical advantages.
Description
Technical Field
The invention discloses a universal variable frequency speed regulation system based on a DSP, and relates to the technical field of digital frequency converters.
Background
The development of digital frequency converters is a product of the world's economic high-speed development. The trend of development is approximately as follows:
1. low electromagnetic noise, silence: the general frequency converter is provided with an alternating current reactor or an active power factor correction circuit APFC at the input side, and adopts a Soft-PWM control technology and the like in the inverter circuit to improve the input current waveform, reduce the harmonic wave of the power grid, and meet the EMC international standard in the aspects of resisting interference and restraining higher harmonic waves so as to realize the conversion of so-called clean electric energy. Such as mitsubishi's flexible PWM control technology, lower noise operation is achieved.
2. Specialization: the digital frequency converter is used for better playing the unique functions of the frequency conversion speed regulation control technology and meeting the requirements of field control as far as possible, and a plurality of special machine types such as a fan water pump air conditioner special type, a crane special type, a constant pressure water supply special type, an alternating current elevator special type, a textile machine special type, a mechanical main shaft transmission special type, a power regeneration special type, an intermediate frequency driving special type, a locomotive traction special type, a single-phase frequency converter and the like are derived.
3. Systemization: the digital frequency converter develops the single machine digitization, the intellectualization and the multifunction, and also develops to the integration and the systemization. The communication, design and data management integrated 'full-integrated automation' (TIA) platform concept proposed by siemens corporation can enable the integrated configuration of a frequency converter, a servo device, a controller, a communication device and the like, and even the automation and driving system, the communication and data management system can be implemented as the driving device is generally embedded into the 'full-integrated automation' system, so as to provide the optimal system function for users.
4. Networking: the digital frequency converter can provide a plurality of compatible communication interfaces, supports a plurality of different communication protocols, is internally provided with an RS485 interface, can input operation commands, set function code data and the like to the universal frequency converter by a personal computer, and can be connected with a field bus by selecting components: profibus-DP, interbus-S, device Net, modbus Plus, CC-Link, LONWORKS, ethernet, CAN Open, T-LINK, etc. Universal frequency converters such as siemens, VACON, fuji, hitachi, mitsubishi, taian, etc. brands can all support several or all of the above types of fieldbuses through the options available individually.
5. Operation foolproof: the solidified 'debugging guide' in the digital frequency converter can guide you to fill the debugging form step by step, any parameters are not needed to be remembered, and the operability is fully embodied. The new generation of MICROMASTER420/440, such as siemens, has made the operation in connection with the technology, installation and debugging very simple by employing a successful concept called "easy to use".
6. Parameter trend graph: the parameter trend graph of the digital frequency converter can timely display the current running state of each signal, and a user can monitor and record running parameters at any time in the debugging process. Such as the advanced operator panel AOP of the new generation MICROMASTER420/440 of siemens, the parameters of the frequency converter can be up-or down-loaded, and up to 31 frequency converter drives can be commissioned and controlled via the USS connection of the fieldbus. AOP may store 10 sets of data. The sets of data stored in the AOP may be loaded directly into the other MICROMASTER420/440 or through the USS.
7. Built-in application software: the digital frequency converter can be internally provided with various application software, and some brands can provide more than 130 kinds of application software so as to meet the requirements of field process control, such as: PID control software, tension control software, speed stage chain, speed following, current balance, frequency converter function setting software, communication software and the like. The function setting software of the frequency converter can set the functions and data communication of the frequency converter in a WINDOWS95/98 environment.
8. Parameter self-adjustment: the user only needs to set the data set codes, and the universal frequency converter can automatically adjust the operation parameters to the optimal state without setting item by item (the vector frequency converter can automatically adjust the motor parameters).
With the progress of industrial production level and the improvement of life quality requirements of people, an alternating current variable frequency speed regulation system has become an indispensable part of daily life and industrial control of human beings. The universal frequency converter is widely applied in the fields of escalator, cable machinery, printing and dyeing equipment, chemical machinery, plastic machinery, oilfield equipment, mining machinery equipment and the like, meets the requirements of human beings on speed regulation products, and simultaneously provides higher requirements on a new generation of speed regulation system. These requirements are mainly reflected in both performance and versatility of the control system.
Disclosure of Invention
The invention provides a universal variable frequency speed regulating system based on a DSP, which not only can realize the large torque starting of an asynchronous motor, but also can realize the wide-range variable frequency speed regulation of the asynchronous motor. The device has the advantages of meeting the starting requirements of various heavy loads, saving energy, reducing consumption and having remarkable economic benefit.
The technical scheme adopted by the invention is as follows:
the utility model provides a general variable frequency speed control system based on DSP, includes main circuit, control circuit, protection circuit, the main circuit includes three-phase rectifier bridge module, intermediate filter module, inverter circuit module, and intermediate filter module is connected to three-phase rectifier bridge module, and inverter circuit module is connected to intermediate filter module, and inverter circuit module connects motor M.
And a noninductive absorption capacitor C3 is connected between the intermediate filtering module and the inverter circuit module.
The three-phase rectifier bridge module comprises a three-phase uncontrolled rectifier circuit and is used for rectifying three-phase mains supply to obtain pulsating direct-current voltage;
the intermediate filtering module is used for removing harmonic components and stabilizing the bus voltage value;
the noninductive absorption capacitor C3 is used for absorbing high-frequency peak voltage and current;
the inverter circuit module is used for outputting alternating pulse voltage by controlling the on-off of the IGBT;
the control circuit comprises a DSP module which is respectively connected with a DSP minimum system, a PWM level conversion circuit, an SCI serial communication circuit, a CAN bus communication circuit, a rotating speed signal processing circuit, an input circuit and an output circuit;
the DSP minimum system consists of an external crystal oscillator, a power supply, a JTAG download port and a filter circuit;
the PWM level conversion circuit comprises a level conversion chip 74LVX4245, the DSP module is connected with an optical coupler TLP559 through the PWM level conversion circuit, and the PWM level conversion circuit is used for converting 3.3V into 5V;
the rotating speed signal processing circuit comprises an optical coupler 6N137 and a signal processing unit, and the photoelectric encoder is connected with the optical coupler 6N137 through the signal processing unit; the signals sent by the photoelectric Encoder are isolated by the signal processing unit and the optocoupler 6N137 to obtain two paths of orthogonal pulse signals of the Encoder_ A, encoder _B, and the two paths of orthogonal pulse signals are respectively input into EQEPA and EQEPB ports of the DSP module for pulse counting so as to calculate the rotating speed value.
The input circuit comprises an optical coupler TLP521 and a light emitting diode LED, wherein the light emitting diode LED is connected with the input side of the optical coupler TLP521, and the output side of the optical coupler TLP521 is connected with the DSP module;
the output circuit comprises an inverter TC74HC07AF, an optocoupler TLP521, a high-voltage high-current octadarlington transistor array ULN2804 and a relay; the inverter TC74HC07AF is connected with the input side of the optical coupler TLP521, the output side of the optical coupler TLP521 is connected with the high-voltage high-current octadarlington transistor array ULN2804, and the high-voltage high-current octadarlington transistor array ULN2804 is connected with the relay;
the protection circuit includes: a first current sensor for detecting a U-phase current; a first current sensor for detecting a V-phase current; a third current sensor for detecting a DC bus current; and the voltage sensor is used for detecting the voltage value of the direct current bus.
The first, second and third current sensors are connected with the DSP module through a current signal conditioning circuit; the first, second and third current sensors obtain current signals, and the current signals are processed by the signal conditioning circuit and then sent to an A/D sampling port of the DSP module for realizing current protection;
the voltage sensor is connected with the DSP module through a voltage signal conditioning circuit;
the voltage signal conditioning circuit comprises sampling resistors R206-1 and R206-2, wherein voltage signals obtained at two ends of the sampling resistors R206-1 and R206-2 are 5V, and the voltage signals are divided into two paths after RC filtering and voltage follow-up: one path is used for hardware overvoltage protection, namely, an overvoltage signal TZ_U is output after being compared with a fixed level 5V and is directly sent to a TZ port of the DSP module; the other path is divided to obtain a signal of 0-3V and the signal is sent to an A/D sampling port of the DSP module.
The noninductive absorption capacitance C3 is a noninductive absorption capacitance of 1 muF/1200 VDC.
The three-phase rectifier bridge module is an MDS50A/1600V three-phase rectifier bridge module, and the main parameters are as follows: withstand 1600V, rated current 50A.
The inverter circuit module is a 7-unit IPM module 7MBP75RA120 of Fuji corporation, and 7 IGBTs, a driving circuit, a protection module and a brake circuit are integrated in the inverter circuit module. Can bear 1200V voltage, and can pass current with the maximum value of 75A, which is enough to meet the design requirement.
The inverter circuit module is externally connected with a fault output ALM terminal, PWM output can be blocked through the microprocessor when in fault, and the protection effect is achieved.
The intermediate filter module is formed by connecting two capacitors C1 and C2 with the voltage of 2200 mu F/400V in series, so that the technical requirement on the filter capacitor is met, and meanwhile, the price and the volume of the capacitor are acceptable.
The control circuit also comprises a direct-current stabilized power supply, U, V phase line voltage of the main circuit is used as input of the power supply circuit, the voltage level of the main circuit is reduced by adopting a linear transformer and then the main circuit is output, and the output alternating current with low voltage level is subjected to full-bridge uncontrollable rectification, three-terminal voltage stabilizing chip voltage stabilization and capacitance filtration to obtain the required direct-current voltage.
The SCI serial communication circuit comprises a MAX485 chip, an optocoupler HCPL-M611 and a matching resistor, wherein the MAX485 chip, the optocoupler HCPL-M611 and the matching resistor are all connected with the DSP module.
The CAN bus communication circuit comprises a CAN bus communication module CTM1050T, and the CAN bus communication module CTM1050T is connected with the DSP module.
The protection circuit comprises an analog comparison circuit and judges whether the current value exceeds a set value or not, so that an overcurrent signal is directly given out, and the overcurrent signal and an ALM terminal of the comprehensive fault alarm signal of the inverter circuit module are used as a line or.
The first, second and third current sensors are LA-50P current sensors.
The DSP module is a TMS320F2808 processor.
The DSP module adds a "brake enable bit" and when this position is "1", the system can only brake effectively.
The universal variable frequency speed regulating system based on the DSP can realize the large-torque starting of the asynchronous motor, can realize wide-range variable frequency speed regulation of the asynchronous motor, and is the optimal operation mode of the asynchronous motor at present. Compared with the direct full-voltage starting and low-voltage soft starting methods of asynchronous motors, the method has obvious technical advantages.
Drawings
Fig. 1 is a system block diagram of the present invention.
Fig. 2 is a main circuit diagram of the frequency converter of the present invention.
Fig. 3 is a schematic diagram of a control circuit of the digitizer according to the present invention.
Fig. 4 is a circuit diagram of a DSP min system according to the present invention.
Fig. 5 is a PWM level shift circuit diagram of the present invention.
FIG. 6 is a diagram of the SCI serial communication circuit of the present invention.
Fig. 7 is a CAN bus communication circuit diagram of the present invention.
Fig. 8 is a circuit diagram of the rotational speed signal processing of the present invention.
Fig. 9 is a diagram of an input circuit of the present invention.
Fig. 10 is an output circuit diagram of the present invention.
Fig. 11 is a circuit diagram of a dc regulated power supply according to the present invention.
Fig. 12 is a U-phase current sampling signal conditioning circuit of the digitizer of the present invention.
Fig. 13 is a V-phase current sampling signal conditioning circuit of the digitizer of the present invention.
Fig. 14 is a dc bus current sampling signal conditioning circuit of the digitizer of the present invention.
Fig. 15 is an overcurrent protection circuit of the digital frequency converter of the invention.
Fig. 16 is a circuit diagram of the overvoltage, undervoltage protection and brake control of the digitizer of the present invention.
Detailed Description
As shown in FIG. 1, the DSP-based universal variable frequency speed regulation system comprises a main circuit, a control circuit and a protection circuit. The main circuit is composed of three parts of a three-phase uncontrolled rectifying link, a filtering link and an inversion link. In fig. 1, the dc voltage output by the rectifier bridge is not stable enough, with harmonic, so as to filter out harmonic components in the dc voltage, so that the bus voltage is more stable, and a capacitor C3 is connected in parallel to two ends of the dc bus. The filtered DC bus voltage can pass through the three-phase controllable inverter bridge to obtain the needed three-phase alternating current, and the driving motor M operates according to the requirement.
The control circuit takes TMS320F2808 as a control core, and peripheral circuits thereof comprise an EEPROM (electrically erasable programmable read-Only memory) expansion circuit, a sampling signal processing circuit, a DAC7512 expansion circuit, a rotating speed encoder input signal processing circuit, an input/output circuit and a communication circuit; and the DSP processes and calculates the internal part of the chip according to the instruction given by the upper computer and the value input by measurement, and outputs PWM waves through the EPWM module. The DSP outputs to a D/A conversion chip DAC7512 through 3I/O ports to be converted into 0-3.3V analog output, so that the change of the intermediate quantity is observed; through 2I/O ports, one control starts and stops, and one control motor M just reverses.
The protection circuit comprises a soft charging circuit, an overvoltage protection circuit, an overcurrent protection circuit, an undervoltage protection circuit diagram, an overheat protection circuit, an ALM protection circuit of the IPM and a brake control circuit. R in FIG. 1 0 The soft charging resistor can play a role in limiting current when being electrified so as to avoid impact of sudden increase of current on capacitance when the electrification is performed, and K is an alternating current contactor and is used for controlling the resistor R 0 When the capacitor is charged, R is the following value 0 Short-circuited to avoid resistive losses during normal operation. The overvoltage, undervoltage protection and overcurrent protection are to detect corresponding physical quantities through voltage and current sensors, and send the detected and processed signals into a DSP for logic judgment, so as to realize corresponding protection functions. Besides the software protection function, the system also designs hardware protection, obtains a protection signal through an analog comparison circuit, directly sends the protection signal to a TZ port of the DSP, immediately blocks PWM output if faults occur, and informs an upper computer through serial port communication. The ALM alarm signal of the IPM is directly sent to the TZ port of the DSP, so that the PWM output is directly blocked when the IPM comprehensive fault occurs. The pump-up limitation in the figure is used for brake control, and once the voltage on the direct current bus is detected to exceed the voltage value when the motor runs, the motor is in a braking state, and the energy flows in the positive direction of the power grid, and the VT needs to be controlled b And is turned on, thereby allowing energy to be dissipated in the brake resistor.
As shown in fig. 2, the main circuit includes a three-phase rectifier bridge module, an intermediate filter module, and an inverter circuit module, where the three-phase rectifier bridge module is connected to the intermediate filter module, and the intermediate filter module is connected to the inverter circuit module. And rectifying the three-phase mains supply through the three-phase rectifier bridge module to obtain pulsating direct-current voltage. Then the harmonic components are removed through the filtering of the intermediate filtering module, so that the bus voltage value is more stable. A noninductive absorption capacitor C3 with the voltage of 1 mu F/1200VDC is added into the main circuit for absorbing high-frequency peak voltage and current. The inverter circuit module outputs the required alternating pulse voltage by controlling the on-off of the IGBT.
And (3) a step of: design of a three-phase rectifier bridge module:
the input of the frequency converter is the mains supply: three-phase 380V alternating current with frequency of 50Hz. The capacity of the frequency converter is designed according to a 20KW asynchronous motor. According to the formula provided by the literature Chen Jian, beijing: higher education Press, 2004", the average value of the DC bus voltage at this time can be calculated as:
no load:
when the load is continuous with current:
taking into account the floating of 5% of the supply voltage, U PNmax ＝566V，U PNmin =489v; when the load is a motor, the power factor is usually 0.78-0.9, so that the maximum value of the bus current can be calculated:
then the average current through each diode in the three-phase rectifier bridge module has a maximum value of I dmax 3=17.5A; considering the floating of the supply voltage, each diode is subjected to a maximum voltage of about 980V.
Considering the cost performance of selected components and the engineering margin, the invention selects the MDS50A/1600V three-phase rectifier bridge module, and the main parameters are as follows: withstand 1600V, rated current 50A.
And II: and (3) designing an intermediate filtering module:
the voltage rectified by the three-phase rectifier bridge module is pulsating and cannot be directly used as input by the inverter circuit module if the voltage is not processed, and a capacitor is needed to be added for filtering. In theory, the filtering capacitance value is larger, and the filtering effect is better. However, the volume of the large-capacity capacitor is generally larger, so that the large-capacity capacitor is inconvenient to be arranged in an experimental prototype; and the price of the large capacity capacitor is more expensive than that of the small capacity capacitor, so that the cost is saved for the merchant. The filter capacitance cannot be made too large. Considering the problems comprehensively, the invention selects two capacitors C1 and C2 with 2200 mu F/400V to be connected in series, thereby not only meeting the technical requirements on filter capacitors, but also being acceptable in price and volume of the capacitors.
Thirdly,: and (3) designing an inverter circuit module:
the inverter circuit module encapsulates the drive circuit and the IGBT together, has overcurrent, overheat and other protection functions, adopts high-speed low-power-consumption devices inside, and has a very strong self-protection function. The power tube also has a fault output ALM terminal, can block PWM output through a microprocessor during faults, plays a role in protection, and is in place in heat dissipation treatment of the power tube. The intelligent power module is introduced, the process of designing the inverter is simplified, the success rate of one-time design is improved, and the intelligent power module is widely adopted at present. In the design of the inverter circuit module of the present invention, the 7-unit IPM module 7MBP75RA120 of fuji corporation is adopted, and 7 IGBTs, a driving circuit, a protection module, and a brake circuit are integrated therein. Can bear 1200V voltage, and can pass current with the maximum value of 75A, which is enough to meet the design requirement.
As shown in FIG. 3, the control circuit comprises a DSP module, and the DSP module is respectively connected with a DSP minimum system, a PWM level conversion circuit, an SCI serial communication circuit, a CAN bus communication circuit, a rotating speed signal processing circuit, an input circuit and an output circuit.
And a DSP module: the control core chip adopted by the invention is a digital signal controller TMS320F2808 of TI company. The chip completes all control algorithms, speed sampling and calculation, output SVPWM waves, current sampling, voltage sampling, overcurrent, overvoltage, undervoltage protection and other functions. Compared with the common TMS320F2812 and other DSP chips, the TMS320F2808 has the following characteristics:
(1) the method comprises the following steps The price is moderate, and the cost performance is high;
(2) the method comprises the following steps The working frequency of 100MHz meets the control requirements of most power electronic devices;
(3) the method comprises the following steps The programming of the C language is supported, the programming is convenient, and the code efficiency is high;
(4) the method comprises the following steps The system has a plurality of enhanced functional modules, so that programming and function realization are facilitated;
(5) the method comprises the following steps The a/D sampling accuracy is high (12 bits).
As shown in fig. 4, the DSP minimum system consists of an external crystal oscillator, a power supply, a JTAG download port and some filter circuits. The external crystal oscillator is an active 20MHz crystal oscillator, and the power supply voltage is 3.3V. For the TMS320F2808 chip, it requires an I/O voltage of 3.3V and a core voltage of 1.8V. For the convenience of design, a power supply chip TPS767D318 matched with TI company is selected, 5V direct current voltage is input into the chip, and after the chip is processed, two paths of direct current voltages of 3.3V and 1.8V are output. For the whole control circuit, magnetic beads are adopted to isolate digital voltage from analog voltage and isolate analog ground from digital ground, and proper capacitors are selected to carry out filtering treatment on all paths of power supplies. In addition, the X5043 chip adopted in the system has the power supply voltage of 3.3V and has the functions of power supply voltage monitoring and EEPROM, and when the power supply voltage is lower than 3.3V, the chip can generate a reset signal to reset the system, and meanwhile, the chip can be used as the EEPROM to save part of control parameters.
A PWM level shift circuit is shown in fig. 5. The signal input end of the optional high-speed optocoupler TLP559 is designed according to a voltage of 5V, and the amplitude of the PWM wave voltage output by the DSP module is 3.3V, so that the level conversion chip 74LVX4245 is required to realize level conversion. The chip can change the direction of voltage conversion by configuring the level of the DIR pin, wherein 3.3V is converted to 5V, and the B port is converted to the A port for output, so that the DIR needs to be connected with a low level according to the data of the chip.
As shown in FIG. 6, the SCI serial communication circuit of the invention adopts an upper computer based on dsPIC30F4011 to communicate with a main machine of the frequency converter, so as to realize the purposes of issuing parameters and instructions from the upper computer to the frequency converter and reading the current state of the frequency converter. The hardware part of the communication adopts a MAX485 chip, and the software complies with Modbus_RTU protocol. In order to avoid the interference caused by communication, an HCPL-M611 optocoupler is added on the DSP side for isolation. In order to suppress echo interference in communication, a matching resistor is added.
As shown in fig. 7, the present invention further reserves a CAN bus communication interface for facilitating the later expansion, and the hardware circuit is implemented by using a CAN bus communication module CTM 1050T.
As shown in fig. 8, the rotation speed signal processing circuit is shown in fig. 8, because the signals sent by the photoelectric Encoder are mostly differential signals, two paths of orthogonal pulse signals of the encoder_ A, encoder _b can be obtained after signal processing and optical coupling isolation, and then the two paths of signals are respectively input into the EQEPA and the EQEPB ports of the DSP for pulse counting to calculate the rotation speed value. The motor steering can be judged by an enhanced QEP module in the DSP. The Encoder_Z is a zero signal and can be used for resetting the pulse count value in the DSP to prevent the count value from overflowing.
The input circuit and the output circuit are shown in fig. 9 and 10. The input circuit comprises an optical coupler TLP521 and a light emitting diode LED, wherein the light emitting diode LED is connected with the input side of the optical coupler TLP521, and the output side of the optical coupler TLP521 is connected with the DSP module. The output circuit comprises an inverter TC74HC07AF, an optocoupler TLP521, a high-voltage high-current octadarlington transistor array ULN2804 and a relay; the inverter TC74HC07AF is connected with the input side of the optical coupler TLP521, the output side of the optical coupler TLP521 is connected with the high-voltage high-current octadarlington transistor array ULN2804, and the high-voltage high-current octadarlington transistor array ULN2804 is connected with a relay.
The input and output ports are indispensable for a complete set of transducer devices. From the practical point of view, it is sometimes necessary to switch some states of the frequency converter by externally giving a certain level signal, but the externally given level signal is provided with external interference, and cannot be directly connected to a general I/O port of the control chip, so that corresponding isolation and processing are required. The internal signal of the frequency converter cannot be directly connected with the outside, and the internal signal can be output after being isolated and processed. The chip as used in fig. 9 functions as an inverter and can reverse the high and low levels. The outputs in fig. 9 are directly active outputs, so that the arrangement can be used for later expansion on one hand, and can be used for indicating through corresponding changes of the level of the I/O port in software debugging on the other hand; the relay output, namely the passive output, is mainly used for external fan and soft charging control, and the relay can be used for achieving the effect of strong and weak electric isolation.
As shown in fig. 11, the dc voltage-stabilized power supply circuit is a reliable dc voltage-stabilized power supply for the frequency converter, which can normally operate for a long time. There are three general power solutions: 1. a silicon controlled power supply; 2. a switching power supply; 3. a linear power supply. The characteristics of good linear power supply precision, easy maintenance and the like are considered. The system adopts a linear power supply as a direct current power supply of the whole device. The design method of the direct current stabilized power supply is shown in fig. 10. The U, V phase line voltage of the main circuit is used as the input of the power circuit, the voltage level of the main circuit is reduced by adopting a linear transformer, the output alternating current with low voltage level is output, and the required direct current voltage is obtained after full-bridge uncontrollable rectification, voltage stabilization by a three-terminal voltage stabilizing chip and capacitance filtering.
Design of a protection circuit:
as can be seen from fig. 2, current feedback values are required to achieve current closed loop, and current models are also required for flux linkage observation. Accurate detection of three-phase currents is therefore very important. Three current sensors are typically employed to detect three of the currents, respectively.
The invention detects U, V two-phase current and direct current bus current, adopts the current sensor of LA-50P, has rated current of 50A, working voltage of + -15V, measuring range of-80A-80A, turns ratio of 1:1000, detection signal output of-80 mA, and can measure DC, AC and pulse current according to the Hall magnetic compensation working principle. Fig. 12 and 13 are two-phase current sampling signal conditioning circuits of U, V, an input current signal is converted into a voltage signal of-3V to 3V through a 41 Ω sampling resistor, and then is clamped through a follower circuit, a bias circuit and a diode, and the voltage range of the finally obtained signal is 0 to 3V, so that the signal can be directly input into a DSP module: A/D sampling port of TMS320F2808. Fig. 14 is a dc bus current sampling signal conditioning circuit, similar to the analysis of fig. 13.
The invention relates to a digital frequency converter protection circuit which comprises overvoltage, undervoltage, overload, overcurrent and overheat protection. Overcurrent protection, current protection can be achieved by obtaining current signals through three current sensors shown in fig. 2-4, processing the signals via a signal conditioning circuit, and then feeding the signals into the a/D sampling port of the DSP module. In order to ensure the reliability, a hardware protection function is added, and whether the current value exceeds a set value can be judged through an analog comparison circuit, so that an overcurrent signal is directly given out, and the overcurrent signal can be used as a line or with an ALM terminal of a comprehensive fault alarm signal of an inverter circuit module, and as shown in fig. 15, a GL end is fed into a TZ port of a DSP module.
The U, V phase current signal processed by the current sampling and conditioning circuit shown in fig. 12-14 is sent to the A/D port of the DSP module to participate in operation and logic judgment, and if the sampling value of a certain phase current exceeds the set range, the system is overloaded.
The voltage value of the direct current bus is obtained through a voltage sensor, so that overvoltage and undervoltage protection and braking control are realized. As shown in FIG. 16, the sampling signal conditioning circuit is characterized in that high-precision sampling resistors R206-1 and R206-2 are 820 omega, and if the voltage of a direct current bus is 800V, the voltage signals obtained at two ends of the sampling resistor are 5V, and the voltage signals are divided into two paths after RC filtering and voltage following. One path is used for hardware overvoltage protection, namely, an overvoltage signal TZ_U is output after being compared with a fixed level 5V and is directly sent to a TZ port of the DSP; the other path is divided to obtain a signal of 0-3V, and the signal is sent to an A/D sampling port of the DSP module to participate in operation and logic judgment. After the logic judgment of the bus voltage value is carried out in the DSP module, three working conditions of overvoltage, braking and undervoltage can be respectively obtained. In addition, in order to avoid the false braking during the acceleration process of the motor, the DSP module is additionally provided with a 'brake permission position', and the system can effectively brake when the position is 1.
Claims (1)
1. General variable frequency speed control system based on DSP, including main circuit, control circuit, protection circuit, its characterized in that: the main circuit comprises a three-phase rectifier bridge module, an intermediate filtering module and an inverter circuit module, wherein the three-phase rectifier bridge module is connected with the intermediate filtering module, the intermediate filtering module is connected with the inverter circuit module, and the inverter circuit module is connected with the motor M;
a noninductive absorption capacitor C3 is connected between the intermediate filtering module and the inverter circuit module;
the three-phase rectifier bridge module comprises a three-phase uncontrolled rectifier circuit and is used for rectifying three-phase mains supply to obtain pulsating direct-current voltage;
the intermediate filtering module is used for removing harmonic components and stabilizing the bus voltage value;
the noninductive absorption capacitor C3 is used for absorbing high-frequency peak voltage and current;
the inverter circuit module is used for outputting alternating pulse voltage by controlling the on-off of the IGBT;
the control circuit comprises a DSP module which is respectively connected with a DSP minimum system, a PWM level conversion circuit, an SCI serial communication circuit, a CAN bus communication circuit, a rotating speed signal processing circuit, an input circuit and an output circuit;
the DSP minimum system consists of an external crystal oscillator, a power supply, a JTAG download port and a filter circuit;
the PWM level conversion circuit comprises a level conversion chip, the DSP module is connected with the optical coupler TLP559 through the PWM level conversion circuit, and the PWM level conversion circuit is used for converting 3.3V into 5V;
the rotating speed signal processing circuit comprises an optical coupler and a signal processing unit, and the photoelectric encoder is connected with the optical coupler through the signal processing unit; the signal sent by the photoelectric Encoder is isolated by the signal processing unit and the optical coupler to obtain two paths of orthogonal pulse signals of the Encoder_ A, encoder _B, and then the two paths of signals are respectively input into EQEPA and EQEPB ports of the DSP module to perform pulse counting so as to calculate a rotating speed value;
the input circuit comprises an optocoupler and a Light Emitting Diode (LED), wherein the LED is connected with the input side of the optocoupler, and the output side of the optocoupler is connected with the DSP module;
the output circuit comprises an inverter, an optocoupler, a high-voltage high-current octadarlington transistor array and a relay; the inverter is connected with the input side of the optocoupler, the output side of the optocoupler is connected with the high-voltage and high-current octadarlington transistor array, and the high-voltage and high-current octadarlington transistor array is connected with the relay;
the protection circuit includes: a first current sensor for detecting a U-phase current; a second current sensor for detecting a V-phase current; a third current sensor for detecting a DC bus current; the voltage sensor is used for detecting the voltage value of the direct current bus;
the first, second and third current sensors are connected with the DSP module through a current signal conditioning circuit; the first, second and third current sensors obtain current signals, and the current signals are processed by the signal conditioning circuit and then sent to an A/D sampling port of the DSP module for realizing current protection;
the voltage sensor is connected with the DSP module through a voltage signal conditioning circuit;
the voltage signal conditioning circuit comprises sampling resistors R206-1 and R206-2, wherein voltage signals obtained at two ends of the sampling resistors R206-1 and R206-2 are 5V, and the voltage signals are divided into two paths after RC filtering and voltage follow-up: one path is used for hardware overvoltage protection, namely, an overvoltage signal TZ_U is output after being compared with a fixed level 5V and is directly sent to a TZ port of the DSP module; the other path of the signal is divided to obtain a signal of 0-3V, the signal is sent to an A/D sampling port of the DSP module to participate in operation and logic judgment, and three working conditions of overvoltage, brake and undervoltage can be respectively obtained after the logic judgment of the bus voltage value in the DSP module; in addition, in order to avoid the false braking in the acceleration process of the motor, an allowable braking position is added in the DSP module, and the system can effectively brake when the position is 1;
the protection circuit comprises an analog comparison circuit and judges whether the current value exceeds a set value or not, so that an overcurrent signal is directly given out, and the overcurrent signal and an ALM terminal of the comprehensive fault alarm signal of the inverter circuit module are used as a line or.
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| RU2680715C1 (en) * | 2017-11-01 | 2019-02-26 | Виктор Николаевич Тимофеев | Power supply for inductor |
| CN108539962A (en) * | 2018-04-27 | 2018-09-14 | 浙江大维高新技术股份有限公司 | A kind of integrated elevator variable frequency device |
| CN211388639U (en) * | 2018-09-18 | 2020-09-01 | 南京德朔实业有限公司 | Electric tool |
| CN109739172A (en) * | 2019-01-03 | 2019-05-10 | 苏州巨联电气有限公司 | A kind of frequency converter checking platform |
| CN110265965A (en) * | 2019-07-05 | 2019-09-20 | 贵州航天控制技术有限公司 | A kind of intelligent protection circuit adapting to high-power electric rudder system |
| CN110474598A (en) * | 2019-08-22 | 2019-11-19 | 广东职业技术学院 | A kind of SPWM frequency conversion speed-adjusting system and its control method based on FPGA |
| CN110690685B (en) * | 2019-09-06 | 2020-11-24 | 珠海格力电器股份有限公司 | High-precision overcurrent protection circuit and method and motor |
| CN113515101A (en) * | 2020-04-10 | 2021-10-19 | 上海埃迪特动力技术有限公司 | Vehicle motor controller auxiliary test equipment that rolls off production line |
| CN112366925A (en) * | 2020-11-05 | 2021-02-12 | 杭州西通电气技术有限公司 | Novel frequency converter drive plate |
| CN113107803B (en) * | 2021-04-13 | 2022-08-19 | 南通大学 | Quick stop device of polyester melt metering pump for chemical industry |
| CN114123759B (en) * | 2021-11-30 | 2024-01-26 | 上海南芯半导体科技股份有限公司 | AC-DC converter and control method thereof |
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