CN204761340U - Three closed -loop control dc -inverter compressors based on DSP - Google Patents

Abstract

The utility model discloses a three closed -loop control dc -inverter compressors based on DSP. This system uses DSP to carry out the processing of velocity feedback and motor commutation signal as main control chip, extensive programmable logic device (CPLD), and opening and turn -offing of three closed -loop control dc -inverter compressors based on DSP design piece IR2130 control inverter circuit MOSFET power tube realizes the PWM control of motor, and motor output drives the actuating mechanism operation. Motor control system carries out real -time communication with the host computer through the communication unit, and DSP receives position feedback signal, current feedback signal, speed feedback signal. The position feedback signal can be regarded as according to the terminal voltage comparative scale of the voltage signal of feedback and unsettled phase winding, and position instruction and position feedback signal formation's deviation signal controls the calculation of rule, output motor control signal.

Description

Based on the Three-loop control DC frequency-changeable compressor of DSP

Technical field

The utility model relates to DC frequency-changeable compressor, particularly relates to the frequency-changeable compressor of the Three-loop control of a kind of novel rotor position method of determining and calculating.

Background technology

The rapid computations ability of dsp chip can make control system carry out computing in real time, its internal structure makes control system realize more complicated control algolithm, speed ring, electric current loop and position ring can be realized in a digital manner, system upgrade and expansion can be carried out by high speed network interfaces, form the brushless DC motor control system realized with Digital Way.At present, the TMS320F2812DSP chip of TI company is widely used in the fields such as motion control, Digit Control Machine Tool, electric power system, self-reacting device.Describe a kind of system controlling brushless direct-current frequency-changeable compressor based on DSP herein.

The integrated plurality of advantages of brushless direct-current frequency-changeable compressor progressively replaces alternating current asynchronous compressor.Due to the structural particularity of compressor.Make its inside cannot installation site transducer.Therefore the rotor-position how correctly detecting motor is the difficult problem faced at present.Existing BLDCM control system adopts monocycle to control mostly, is difficult to the requirement simultaneously meeting the rapidity of system, stability and accuracy.TMS320F2812 type DSP is adopted to be Master control chip herein.EPM3128ATCl00-10 type CPLD is adopted to realize the logic commutation of BLDCM and speed calculates.Achieve the three close-loop control of the electric current loop of control system, speed ring, position ring.Brushless DC motor without sensor generally adopts the back-emf zero crossing detecting the generation of motor winding to obtain rotor position information, but owing to being mixed with PWM hard pulse interference in back-emf, if adopt the method for filtering to obtain back electromotive force, phase shift and time delay can be caused, and can cause when low speed commutation failure is caused to the excessive attenuation of back-emf.The terminal voltage of the unsettled phase winding of the design's direct-detection during PWM-on.Run by dsp software and the half of itself and DC bus-bar voltage is compared and then obtains back-emf zero crossing.This kind of method makes hardware configuration simple, and cost is low.

Summary of the invention

The utility model is intended to develop a set of with low cost, high accuracy, high sensitivity, meets various application scenarios high-performance direct current frequency-changeable compressor, its motor control principle is not only applicable to compressor, also can be used for other to motor sensitivity, the place that precise requirements is high, as electric gripper, gyroscope, digital machine etc.

The utility model take DSP as main control chip, electric machine control system and host computer carry out real time communication by communication unit, after DSP receiving position feedback signal, current feedback signal, feedback speed signal, to compare with the terminal voltage of unsettled phase winding according to the voltage signal of feedback and calculate position feed back signal, the deviation signal that position command and position feed back signal are formed carries out the calculating of control law, output motor control signal.Brshless DC motor three close-loop control design sheet IR2130 based on DSP+CPLD controls opening and shutoff of inverter circuit MOSFET power tube, and the PWM realizing motor controls.Current of electric sends into DSP after current sampling circuit and isolating amplifier circuit, forms electric current loop.Scale programmable logic device (CPLD) carries out the process of velocity feedback and motor commutation signal.Motor exports and drives actuator's running.

CPLD receives the back electromotive force of motor winding, through the process of internal logic circuit, forms the conductivity control signal of No. four inverters, is used for controlling the powering order of motor winding; The digital phase-locked loop 74LS297 built-in by CPLD carries out phase-locked process, complete to motor speed constant control.Utilize CPLD phase-locked loop and commutation treatment circuit to be packaged together, form a complete speed feedback control module.

Utility model is the Three-loop control frequency-changeable compressor based on DSP+CPLD+ novel rotor position method of determining and calculating, the chief component of this system: control module, data acquisition circuit, power driving circuit.

Control module: adopt TMS320F2812 type DSP to be Master control chip herein, accepts the feedback digital signal of programmable logic device (CPLD) conversion, produces drive control signal PWM ripple, and then controls the rotating speed of brshless DC motor.

Data acquisition circuit: comprise current acquisition feedback, rate signal collection and rotor-position estimation circuit and form Three-loop control loop.Wherein rotor-position method of determining and calculating is in PWM conduction period, and the back-emf of unsettled winding is superimposed upon on 1/2 supply voltage, and its waveform is correctly reflected on winding port, thus can to sample the voltage of this port in PWM conduction period each time, judge zero crossing.

Power driving circuit: adopt three phase full bridge to drive, the mode that upper brachium pontis power MOSFET tube carries out PWM controls.Power component adopts N-channel MOS FET pipe IRF250.Driving element adopts raster data model special circuit IR2130.Its exclusive HVIC technology makes it can be used for driving and be operated in busbar voltage up to the MOSFET element in the circuit of 600V.

(1) the power drive drive circuit of frequency-changeable compressor

Employing three phase full bridge drives, and the mode that upper brachium pontis power MOSFET tube carries out PWM controls.Consider in design that hardware circuit welds simple, therefore have employed P-channel field-effect transistor (PEFT) pipe and N channel field-effect pipe forms three phase full bridge jointly.Wherein go up the field effect transistor IRF9540 that brachium pontis adopts P raceway groove, lower brachium pontis adopts field effect transistor IRF540 composition.In the design of drive circuit, the driving of the pipe up and down of brachium pontis altogether, therefore can not will distribute different independent current sources to the optocoupler output that upper and lower bridge arm drives.The driving of three lower pipes then altogether, therefore for the output driving optocoupler, can have needs two groups of independent current sources altogether.

(2) rotor position detection circuit

For the detection of zero crossing.Directly back-emf signal can be converted to digital quantity by analog quantity by the A/D mouth of DSP.Then compared by the method for software and the DC bus-bar voltage of 1/2, obtain rotor zero crossing.The benefit done like this is that system is simple, crosses zero propagation less.But require high for the Anti-interference Design of system hardware, increase the difficulty of soft and hardware design.And be difficult to application in the occasion that some interference ratio are stronger.Consider above-mentioned reason.Devise the measuring circuit of electric machine without sensor rotor-position, as shown in Figure 1.This circuit has back-EMF determination and conditioning functions concurrently.Obtain back-emf signal from X/Y/Z connecting terminal of motor, need first high-voltage signal to be decayed to the suitable scope that can measure.In figure, the terminal voltage of X phase produces the voltage division signal X-DIV of X opposite potential after R18, R19, R20 and R5, R10 dividing potential drop.Equally, busbar voltage VDC also needs to adjust to suitable scope after resistance R27, R28, R29, R8 and R13 dividing potential drop, produces U_DIV signal.X phase voltage division signal X_DIV is linked into the input in the same way of analog voltage comparator IC06 (LM339) after the filter circuit filtering that R14 and C4 forms.And DC bus voltage division signal U_DIV is after electric capacity C7, C8 filtering, and be linked into the inverting input of comparator through resistance R16.Comparator output produces zero cross signal output X_INT and is linked into the corresponding external pin of MCU after R3 pull-up resistor.For the motor that inductance value is less, the back-emf signal of generation is less.The back-emf signal zero crossing detected is caused to lag behind actual back-emf zero crossing.Delayedly the inaccurate of commutation will be caused too much.Because native system adopts PWM_ON modulation system, resistance R30, R31 can be introduced in circuit and address this problem with R32 (noting the mode be connected).For X phase, when detecting rising edge zero crossing, investigate the end of oppisite phase voltage of X opposite potential signal comparator.As shown in Figure 2, now electric current flows to Y phase terminal by Z phase terminal, and in these 60 ° of sectors.Y phase terminal and DC bus negative terminal normal open, therefore the level of Y_DIV is ground.By the dividing potential drop of resistance R33 and resistance R32, make the end of oppisite phase voltage ratio reference voltage U-DIV of X phase comparator low, therefore suitably can shift to an earlier date the rising edge zero crossing time that comparator exports.Equally, when detecting X phase trailing edge zero crossing, due in these 60 ° of sectors, electric current flows to Z phase terminal by Y phase terminal, and the anode normal open of Y phase terminal and DC bus.Y-DIV is 2 times of U-DIV voltages.The end of oppisite phase input voltage of comparator can be promoted by resistance R32, thus also can suitably shift to an earlier date the opportunity that comparator detects zero crossing.Adjustment resistance size can adjust the zero crossing time within the specific limits, software can be coordinated to exchange the phase time carry out adequate compensation time necessary.

(3) system composition and operation principle

The three close-loop control block diagram of three phase BLDC M as shown in Figure 2.Innermost ring is electric current loop, and secondary inner ring is speed ring, and most outer shroud is position ring.This three close-loop control take Position Control as final goal, and given position and position feedback amount form deviation, produce speed reference amount after position adjustments.The deviation of it and velocity feedback quantity regulates through speed

Rear formation current reference amount.The deviation of it and current feedback amount forms the controlled quentity controlled variable of PWM duty ratio after Current adjustment.To compare with the terminal voltage of unsettled phase winding according to the voltage signal of feedback and calculate position feed back signal, output motor control signal realizes the speeds control of motor, finally realizes the Position Control of whole system.

The block diagram of system as shown in Figure 3.The basic functional principle of the three close-loop control system of BLDCM is: 1. electric machine control system and host computer carry out real time communication by communication unit.2. after DSP receiving position feedback signal, current feedback signal, feedback speed signal, the deviation signal formed according to position command and position feed back signal carries out the calculating of control law, output motor control signal, motor control signal carries out logical process and produces the phase sequence that 6 tunnels control power tube switch, by buffer circuit input driving circuit.4. drive circuit adopts three phase full bridge mode, brachium pontis modulation system in employing, adopts driving chip IR2130 to control opening and shutoff of inverter circuit MOSFET power tube, and the PWM realizing motor controls; 5. current of electric sends into DSP after current sampling circuit and isolating amplifier circuit, forms electric current loop.CPLD receives the number of times of inverse electromotive force, calculates motor speed information, sends into DSP, forms speed ring.Give dsp software by the terminal voltage of the unsettled phase winding of direct-detection during PWM-ON to run, the half of itself and DC bus-bar voltage is compared and then obtains back-emf zero crossing, feeds back to DSP by position sampling, amplifying circuit, realize position ring.

Accompanying drawing explanation

Fig. 1 is rotor position detection circuit

Fig. 2 is the three close-loop control block diagram of three phase BLDC M

Fig. 3 is the block diagram of system

Embodiment

The novel rotor position measuring and calculating principle of the utility model institute foundation as shown in Figure 1, in PWM conduction period, the terminal voltage of unsettled winding equals superposing of back-emf and 1/2 supply voltage, therefore can obtain back-emf zero crossing by the terminal voltage of this winding and 1/2 supply voltage being compared.In PWM conduction period, the back-emf of unsettled winding is superimposed upon on 1/2 supply voltage, and its waveform is correctly reflected on winding port, thus can to sample the voltage of this port in PWM conduction period each time, judge zero crossing.

In Fig. 2, this three close-loop control take Position Control as final goal, and given position and position feedback amount form deviation, produce speed reference amount after position adjustments.The deviation of it and velocity feedback quantity regulates through speed, forms closed-loop control.

Fig. 3 is the theory of constitution figure of whole system, current signal is collected from drive circuit, DSP is sent into after isolating amplifier circuit, speed control signal is obtained through DSP process, pass to programmable logic controller (PLC) CPLD, produce the drive singal of power circuit after comparison operation, after buffer circuit, control the power output of drive circuit, and then control the stable of rotating speed.The unsettled winding terminal voltage signal obtained from brushless electric machine sampling sends into CPLD, digital signal is obtained after A/D conversion, send into DSP process and draw rotor-position, and then generation motor control signal, power drive signal is produced after giving CPLD, after buffer circuit, control power stage, and then realize the control of motor rotor position.

Claims (1)

1. based on the Three-loop control DC frequency-changeable compressor of DSP, the chief component of this system: control module, data acquisition circuit, power driving circuit,

Control module: adopt TMS320F2812 type DSP to be Master control chip herein, accepts the feedback digital signal of programmable logic device (CPLD) conversion, produces drive control signal PWM ripple, and then controls the rotating speed of brshless DC motor;

Data acquisition circuit: the collection that synchronously can realize current feedback signal, feedback speed signal, position feed back signal;

Power driving circuit: adopt three phase full bridge to drive, the mode that upper brachium pontis power MOSFET tube carries out PWM controls, power component adopts N-channel MOS FET pipe IRF250, and driving element adopts raster data model special circuit IR2130.