The abstract take TI Corporation’s motor control special-purpose chip TMS320LF2407aDSP as the example, in the introduction electric power electronic installation control system’s hardware design plan. Including DSP level switch, clock, replacement, decoding, piece external storage, keyboard, liquid crystal display and E2PROM electric circuit and essential peripheral circuit.
Key word DSP hardware design electric power electronic installation PCB
Introduction
In the modern high performance electric power electron and in the alternating current machine control system, DSP already substituted for the micro controller to become controller’s core. Its fast formidable operation and handling ability as well as parallel running’s ability, has satisfied the electric power electronic installation control system to timely and the processing algorithm complex request, and for the new theory which and the new algorithm application developed unceasingly has laid the technology base.
C240x series DSP faces numerical control system’s new generation digital signal processor. This controller collection real-time processing ability and the controller design function in a body, have provided an ideal solution for the control system application. Its internal Harvard structure causes the data space and the procedure space separation, independent data bus and program bus permission program data concurrent operation; The special-purpose hardware multiplier raised the operating speed enormously; Has the unique counter addressing system, can carry on the fast Fournier transformation operation highly effective; The command system uses the stream line operation, reduced the instruction cycle; Selects the memory mapping method to manage I/0, can expand the peripheral circuit conveniently nimbly.
1 main circuit hardware design
1.1 system system design
Generally electric power electronic installation control system’s gross structure as shown in Figure 1. Introduces various units in detail the function and the hardware circuit.
1.2 level switches
TMS320LF2407a (hereafter refers to as 2407a) to use the 3.3V electricity, reduced the chip power loss; But the commonly used direct-current power supply is 5V, must therefore consider the level switch question. One method is uses the adjustable direct-current power supply to obtain the 3.3V voltage directly, but is like this very difficult to guarantee that the supply voltage the stability, affects DSP the normal operation. Another method uses the special power source chip, reduces to 3.3 5 V voltages v. TPS76833, TPS76HD318, MAX604 are the commonly used level switch chips. Figure 2 is uses MAX604 to realize the electronic communication electric circuit. Parallel plays the constant voltage role between the power source and the place electric capacity.
1.3 clocks
Is different with the common microprocessor, C240x the series DSP use hangs meets each kind of clock signal which needs on the internal peripheral device main line’s phase-locked loop clock module (PLL) synthesis system (the CPU clock, system clock, to simulate clock and watch-dog clock). External clock signal after the PLL frequency multiplication synthesizes the system clock frequency. As shown in Figure 3, the external clock signal crystal oscillator provides by lO the MHz, (SCSR1) establishes 4 frequency multiplication factors after the systems control and the condition register, 2407a DSP by biggest clock rate (40MHz) work. Through inspects the DSP clock output pin (CLK0UT) frequency, may judge the DSP chip whether to start the normal work. The PLL module uses the exterior filter return route blanket vibration and the electromagnetic interference. The filter return route meets by PLL between filter input pin PLLF and PLLF2 resistance Rl and electric capacity Cl, C2 is composed. Electric capacity Cl, C2 must be the nonpolarity electric capacity. Under the different oscillator frequency, R1, Cl, the C2 value is different, commonly used parameter combination like table l arranges in order. PLL module power source pin PLLVCCA separately through magnetism bead and 0.1μF the electric capacity and digital power source pin VDD and the digital pin VSS connection, the constitution low-pass filtering electric circuit, guarantees the clock module the reliable power supply.
1.4 piece of external memories
2407aDSP may visit the procedure storage space is the 64K character, decides its collocation method according to the MP/MC pin’s electron. When MP/MC is the low level, the internal Flash storage space enables, the address range is the 0000h~7FFFFh,8000h~FFFFh address leaves the exterior program memory. When MP/MC is the high level, internal Flash is forbidden, 64 K character storage space is located in completely the exterior program memory, namely can only read the data from the piece external memory, causes when the simulation debugging is quite easy through the simulator to the red-tape operation. 2407a DSP has the 64K 16 bit data memory space, 32 K character’s internal memory address range is 0000h~7FFFh, including memory mapping register, DARAM and peripheral device mapping register. Moreover, the address range is the 8000h~FFFPh 32 K character leaves the exterior data-carrier storage space. Piece targets and so on external memory’s choice main consideration voltage, capacity, speed. This article uses the working voltage 3.3 V, the capacity 64K×16 position, access time 15 ns high speed static RAM, IS6lLV6416-15T takes the piece external memory. As shown in Figure 4, the piece external memory’s data, the address wire correspond connected separately with DSP; The output enables pin OE and the input enables pin WE to read separately with DSP selects DSPRD to be connected. When simulation debugging, with jumps the line to select patches or strips of land as worth saving for seed pin DSPWE and DSP procedure space selection pin CE is connected, when the exterior program memory uses. After the procedure fever writes about internal Flash, selects patches or strips of land as worth saving for seed pin CE and DSP data space selection pin DSPDS is connected, when the exterior data-carrier storage uses.
1.5 decoding circuits
The GAL component is the logical component which develops in the PAL component foundation. May the electricity rewrite the new programmable logical component which as one kind, may duplicate programs, may encrypt, it has the speed to be quick, the capacity is big, the power loss is low moreover designs the nimble merit. This article uses GAL16V8D to take the decoding chip, the input signal has DSP to read enables, to write enables, the data space selection, the procedure space selection, the I/O space selection and the high 5 address wires, after logical combination, outputs periphery components and so on A/D to select patches or strips of land as worth saving for seed the signal.
1.6 reset circuits
2407aDSP has two kind of replacement sources, the external reset pin replacement and the procedure surveillance timer (watch-dog) repositions. The replacement pin (133) is a I/O foot, the normal state pulls the resistance through on to receive a telegram the source. When has the internal replacement event occurs, this pin is actuated for the low level output mode, other chips provides the reset signal to the system in; When has the external reset event to occur (hand reset, on electricity replacement, owes voltage replacement and so on), this pin is the input mode, simultaneously will reposition interrupt vector 0000H to load to program counter PC, causes the procedure to make a fresh start to carry out. TL7705A has processes the electricity replacement, to owe the voltage examination replacement, the hand reset function. This article realizes the external reset signal management function with it, its reset signal output pin and the DSP replacement pin is connected, electric circuit as shown in Figure 5.
1.7 serial E2PROM
Because is burnt writes in internal procedure Flash the procedure when the movement cannot rewrite, but in the practical work condition must according to need to carry on the establishment to some parameters, therefore, expanded a model for the control system is X5043PI-2.7, the storage capacity is 4K serial E2PROM, realizes the parameter establishment, the memory function with the DSP serial peripheral device interface module (SPI) connection, as shown in Figure 6.
SPICLK is the SPI unit clock signal output pin, is X5043PI-2.7 provides the clock signal. SPISIMO is the driven input, the initiative output pin, is connected with the X5043 PI-2.7 driven input pin; SPISOMI is the driven output, the initiative input pin, is connected with the X5043 PI-2.7 driven output pin. SPISTE takes the general I/O mouth use, is X5043PI-2.7 provides selects patches or strips of land as worth saving for seed the signal.
2 periphery hardware circuit design
2.1 signal recuperations and A/D transformation
In electrical power system’s voltage electric current signal cannot deliver a/D component’s input end generally to supply the transformation directly, but must pass through PT, CT to reduce the first voltage electric current, then after pretreatments and so on mutual inductor, signal recuperation transforms for A/D. In the chart feedback resistance R2 and R3 use for to adjust the output signal the size. Electric capacity C2 and adjustable resistance R1 uses for to compensate mutual inductor’s inherent phase-shift. Electric capacity Cl and C5 are the 400~l000pF small electric capacities, uses for the decoupling and the filter. Two tie hands behind the back the diode uses for to protect the operational amplifier. The operational amplifier regards the accuracy requirement to decide, commonly used precision and stable good OP07. The operational amplifier supply voltage usually takes ±15V or ±12V. Transports puts LT084 to meet the form which the emitter follows, plays the impedance matching the role.
A/D transformation is in control system’s necessary important link, its conversion accuracy has decided the entire control system performance fit and unfit quality. Although 2407aDSP built-in 10 high speed A/D module, but this module has the following shortcoming; Can only receive 0~3.3V the unipolarity signal input, needs other design restriction regarding the exchange signal to lift presses the electric circuit; In the identical sorting various channels crosstalk is serious; 10 conversion accuracies satisfy the high performance system’s request with difficulty. This article selects Maxim Corporation’s 14 high speed A/D chip MAXl25 to take the exterior modulus switch. Its input signal scope ±5 V, the channel receives most greatly bearing may reach ±17V, simplified the signal recuperation electric circuit; Single-channel switching time 3μs; Has A, the B two group of signal input ends, each group of four input channel, built-in four group sampling retainer. MAXl25 may with the DSP multi-tasking, thus lightened the DSP work load. The MAXl25 data, the address wire through main line isolation actuation chip 74HC245 and the 2407aDSP data line connection, select patches or strips of land as worth saving for seed the signal to provide by GAL, circuit structure as shown in Figure 4.
2.2 keyboards and liquid crystal display
2407a DSP has reaches 41 general, the bidirectional digital I/O pin, majority is the basic function and the general I/O function multiplying. Establishes the IOPF0~IOPF5 six ports as the general I/O mouth input mode, realizes the keyboard entry function. The liquid-crystal display uses the Inner Tibet T6963C control driver graph liquid crystal display module. T6963C is the large-scale lattice type graph liquid crystal display controller, carries on the instruction and the data transfer through 8 bit parallel data bus and a group of control bus. Selects the indirect operation method to realize to the liquid crystal display module control, namely DSP IOPE0~IOPE7 and the T6963C data line is connected, IOPB4~IOPB7 writes the gating signal with T6963C, to read the gating signal, to select patches or strips of land as worth saving for seed the signal and the port select signal separately is connected, realizes the control function. Compares with the direct access mode, the indirect way lightened the main line burden. The keyboard and liquid crystal display circuit structure as shown in Figure 8.
2.3 synchronizing circuit design
In the installment, the power component’s control signal must take some time reference as the reference, therefore synchronized signal phase accurate immediate influence electric power electronic installation performance. Usually the synchronized signal sends the system supply voltage. Figure 9 is the synchronized signal gathering electric circuit, a side voltage after the PT voltage dropping, after the pass band center frequency is the 50Hz hardware bandpass filter filter, comparator LM311 will exchange the sinusoidal signal to transform into the frequency synchronism square-wave signal, again after AND gate reshaping uses up pair 4N25 to realize the isolation and the level switch, the output signal sends in DSP the capture pin, jumps for the capture unit on along interrupts. Through disposes Rl, Cl, R2, the C2 parameter reasonably, may realize to the 50Hz desired signal not phase-shift filter link, thus avoided gathering the additional phase-shift which the electric circuit brought.
3 manufacture the PCB board matters needing attention
①Controller’s PCB board is best makes four plywood (i.e. besides top layer and first floor, increased power source level and stratum, may places with inner layer division technology 3.3V and 5V, simulation and digit places), may enhance overall system’s resistance to interference obviously. In ordinary circumstances, four plywood compared to two plywood noise low 20 dB. Although four plywood effects are good, but the manufacture expense is high, and not Yi Chacuo. The double kneading board should better spreads the copper in the top layer and the first floor, separately with system digit grounding and power line connection, may also have the very good antijamming effect.
②The copper membrane line width’s minimum value is decided in winds through its electric current size, generally is not suitable is smaller than O.2 mm. So long as the circuit wafer area is not special limits, the line width and the spacing should better select 0.3mm. Usually in the situation, the l~1.5mm line width permission winds through 2 The electric currents. The grounding and the power line width should better not be smaller than l mm.
③Protel 99 SE has not provided 2407the seal, needs the size which provides based on the original text material to found voluntarily. Produce the seal with the Prote1 99 SE guides both to be convenient automatically, the precision and is high. Because 2407a is pastes the piece type seal, the pin is tiny, the spacing is narrow. The suggestion supposes the pin for long 1.50mm, extends 0.35mm, pin spacing 0.50mm. is like this easy to weld, is not easy to create the short circuit.
④All connects the DSP clock module the wire to be as far as possible short. When connects the PLL pin, should pay attention to the following several aspects: Uses the short lead wire to connect the PLLVCCA pin to the low pass filter; Caused the shunt capacitor to connect PLLVCCA and VSS recently; Causes the ring circuit area which these wires, the chip and the shunt capacitor form to be smallest. The area is bigger, then the electromagnetic interference is bigger.
⑤On the PCB board’s digit should separate the wiring with the simulation, through the inductance or magnetism bead simple point connection, avoids disturbing mutually. Because general digital circuit’s antijamming ability, the TTL electric circuit’s noise margin is the 0.4~0.6V, CMOS digital circuit’s noise margin is supply voltage O.3~0.45 time; But analogous circuit part, so long as has the microvolt level noise, sufficiently enables its work to be normal.
⑥Nearby bridges 0.Ol~0.1μF the decoupling electric capacity in DSP and between other chip’s power source and the place, provides with the absorption chip passes the power failure instantaneous charging and discharging electrical energy, and can the bypass chip produce high frequency noise.
4 conclusions
Based on the TMS320LF2407aDSP electric power electronic installation controller, has the versatility. Through uses in the active electric power filter installment, proved that this control system various units operation reliable, the whole coordination is good. To engineers and technicians who is engaged in the related hardware design, has certain reference value.
please send me the matlab-simulink block diagram of three phase induction motor.