Abstract: As the core takes the signal production and the processing part take TMS320V33, matches completes the scope, the frequency, the phase control, the warning, the demonstration by the corresponding peripheral circuit and so on a series of functions. From the design high accuracy power source has the precision to be high, the speed is quick, stable high characteristic.
Key word: DSP; Single-phase precision power source; Hardware
1. introduction
Each kind of power source is obtaining more and more applications in the modern current collector, is also getting higher and higher to the precision request, the traditional power source design has not been able to meet people’s need to a great extent in some domains. The DSP software programming is flexible, the degree-of-freedom is big, the true-time operation speed, data-handling capacity is high. This article take TMS320VC33 DSP as a core, designs one kind of processing speed and the accuracy high single-phase precision power source, satisfies people’s actual need.
2. power source signal production and control
The power source signal divides into the voltage signal and electric current signal two, is the sine wave signal. The identical time has the same frequency, not necessarily has the same phase and the scope. We first design the voltage sine wave signal the production.
The separate sine wave’s production is obtains the corresponding time through each separate cycle to change the sine wave the peak-to-peak value and outputs obtains. The second method is lets function y=sin(nT) from calculate n 0 to the N-1 value, establishes a table in the program memory to store these data. The electric current sine wave’s production principle and the production process and the voltage sine wave are completely same, is only because of the phase reason, but takes the table in the identical time the value to be different.
The TMS320C3X event supervisor has two 32 general timer modules. Each timer has two operating modes and the interior and the external clock. May use the timer module the time-gap which assigns or records the external event to C3X or the exterior sending a letter number. They may take the independent time base work, the timer interrupt are an internal interrupt. Its use catches the cyclical occurrence including the control system in; Provides the time reference for the orthogonal encoder electric circuit pulse circuit and the capture unit’s operation. Have the comparison output for the entire comparison unit and the list comparison unit and the related PWM electric circuit and so on. In each general timer the hard core is 32 counters, the counting scope is 0~4294967296 pulses. The counter impulse may by the internal clock after the frequency division production, be possible to provide the clock by the exterior pin. Because this product’s frequency is adjustable, may use the timer to come to take out each spot in certain time in ROM the sine wave value, may also use the external connection component to change the frequency. Uses the latter method in here us. The principle is changes the frequency with 8253 two counting channels, block diagram as shown in Figure 1: Produces the 180HZ clock by MC14060, after passing through the frequency division, produces the Nf clock. Because requests the frequency must have precisely to two decimals, then 8253 channel 2 register value hypothesis is 100. We take the time separate in this system to select N=720 every week, but the system request’s phase angle precision is 0.0, therefore decides as two separate between fetching gap 5 count cycles. Supposes the expectation sine wave frequency is f, 1 obtains the precise frequency value by 8253 channels as the feedback. In the channel 1 register completes time sends out a signal of stop to DSP, after receiving the interrupt, the DSP transmission data to the voltage and the electric current A/D switch, completes a separate value. When changes the frequency through the keyboard, only needs through routine calculation certain value to read in 8253 channel 0 registers then to achieve the change frequency the goal.
Figure 1 frequency channel’s block diagram
TMS320C33 and its periphery chip connection. Its instruction may carries on visit to the internal I/O register and the exterior I/O port, use address wire 4 visits the I/O periphery chip. The I/O space’s allocation may draw support the decoding component. 74154 are one 4 to 16 decoders, takes the input by the DSP high address, the DSP I/O space enables the pin to control the decoder to enable the pin. Its output enables the end input as the DSP periphery chip periphery pin. The output and the periphery chip select patches or strips of land as worth saving for seed connected, achieves assigns the I/O space the goal.
3. D/A transforms hardware composition
Produces the sine wave which with DSP and outputs is the separate digital signal, must turn it the continual simulated signal to need to pass through the D/A transformation; Must realize the sine power source signal scope to be controllable, must change D/A through DSP the reference voltage, the reference voltage provides by DSP. This system we select DAC083 the D/A switch, because DAC0832 has two 8 registers and a 8 D/A switch, but the DSP output signal is 16. Therefore needs two piece of DAC0832 to be parallel.
Reference voltage D/A which including electric current D/The voltage transforms transforms the reference voltage D/A transformation which and voltage D/A transforms to transform, output voltage D/A transforms, electric current D/A transforms the reference voltage D/A transformation and voltage D/A transforms reference voltage D/A transforms basically same, output voltage’s D/A transformation and output current’s D/A transformation, their circuit diagram basically is consistent, only then the register enables the signal not to be the same. As space is limited, only gives as shown in Figure in this 3 the D/A transformation circuit diagram which the power source outputs. The DAC0832 data line and the DSP data limit meets connected, when the decoder selects, the political string wave voltage signal input voltage D/A switch’s input register, then the decoder selects, the sinusoidal current signal input electric current D/A switch’s input register, then the decoder selects, the voltage D/A switch and at the same time the electric current D/A switch’s input register sends in the data the DAC register, simultaneously carries on the D/A transformation.
Figure 3 the power source outputs D/A switching circuit
4. Power source signal output and examination
Power source signal after the D/A transformation and filter, again after forward feed, feedback, PI regulator’s electric circuit the output voltage already achieved the very high precision and the stability, again after the power amplifier, enters the system output part. In the output unit, we must examine the power source signal to use in feeding back the compensation.
4.1 voltage signal output and examination
Electric circuit like chart 4, A for operational amplifier’s out-port, passes through the multi-tap current transformer to be possible to obtain 380V, 220V, the 60V output voltage separately, the electric circuit mutual inductor’s three taps uses three relay J380V, J220V, J60V and the out-port separately
Connected, relay’s closing controls by DSP, namely from the keyboard entry order, the voltage out-port then outputs the corresponding rank the voltage.
Figure 4 voltage signal output and examination
4.2 electric current signal output and examination
Electric circuit like chart 5, is the same with the voltage output’s electric circuit, A spot for power amplifier’s out-port, based on obtains the detection signal Urf same principle, obtains detection signal Irf, is only the setting resistance resistance number is 0.15 ohm. Obtains the electric current output through the current transformer, the electric current output obtains the detection signal again through another current transformer. Two current transformers are three taps. Three pair of taps pass through three relay J1A, J5A, the J10A connection separately, uses in current transformer’s public end which examines namely for electric current out-port.
Figure 5 electric current examination compensating circuit
5 feedback enlargements and alarm circuit
In order to guarantee the power source outputs precision, therefore has designed a feedback and the amplifying circuit between the D/A transformation and the output. Meanwhile in the product, in power source’s output cannot present the pressure circuit short circuit and the current circuit opening situation. Therefore should increase in the electric circuit
Figure 6 the feedback enlarges, the alarm circuit
Alarm circuit. The alarm circuit must include the light warning and the sound warning. As shown in Figure 6, the electric circuit divides into three parts: Amplifying circuit, alarm circuit and feedback circuit. The smooth sine wave power source signal takes the forward feed signal continuously after the D/A transformation and the filter at the same time, passes through the follower and detection signal Uwf (Iwf) after reverse with after that signal adding together, they and after a PID regulator with forward feed signal Un, after detection signal Urf (Irf) adds together, inputs the PI regulator, obtains value namely for input amplifying circuit’s U0. After and detection signal Urf (Irf) passes through the reverse follower, obtains inputs DSP a/D switching circuit’s signal. In the electric circuit, needs to examine the output voltage and the electric current takes the feedback signal, uses for to input DSP, demonstrates the scope. Its schematic diagram as shown in Figure 7: Analog switch CD4051 under the control signal XF1 control unceasingly to the voltage which and the electric current feeds back
Figure 7 voltage and current feedback electric circuit block diagram
Carries on the sampling, in two cycles which is near separately to AD7135 input voltage and electric current signal. The simulation quantity inputs AD7135 to transform into the digital quantity, after the transformation finished, the data is divided 5 outputs, altogether 5 BCD codes were D5-D1 with its correspondence, whenever the AD7135 transformation completed, transmitted an interrupt pulse to C33, C33 interrupts one time, read in a BCD code data, when fifth time interrupted, after namely last data acquisition, stopped the AD transformation. AD transforms data after the latch enters DSP, and demonstrates the voltage and the electric current value separately in the monitor.
In addition, to share aspect and so on DSP analysis, management duties, when system design to was responsible with the superior machine correspondence serial asynchronous to pass specially has made unguardedly also the corresponding expansion; In order to be advantageous for the man-machine conversation, but also has the oscillator way clock circuit, MAX811 and the DSP connection’s reset circuit, designs and so on keyboard display circuit, as space is limited, leave out.
6. conclusion
The design single-phase high accuracy power source uses TMS320V33 to take its signal production and the processing part, and completes the scope, the frequency, the phase control, the warning demonstration and so on a series of duties. Selects DAC0832 to take the D/A transformation module, transforms separately the separate DSP sinusoidal output signal as the corresponding analogue voltage signal and the simulation electric current signal, and uses PA03 to take the power amplification component. Are composed the man-machine conversation window by the keyboard and the monitor. The power source signal scope, the frequency, the phase requirements achieve through the keyboard control, the frequency and the phase the separate sinusoidal signal control which produces by DSP, the scope value control completely by DSP, D/A transforms the reference voltage peak-to-peak value and the relay close meet the requirements. The output power source signal’s speed and the precision besides rely on the DSP performance, but also with the periphery component memory, the D/A switch, the power amplifier and other anti- allows the analog switch electric circuit to concern. Expands 16 bit parallel D/A with two piece of ADC0832 to transform raises the speed. Uses low being out of balance, slightly warm floats, extends the input OP07 to take the operational amplifier, uses the high accuracy, the high efficiency, power loss small PA03 to take the power amplifier. Also designed the electric current compensating circuit, the PI regulation circuit to guarantee the precision. Has the precision using this design power source in the practical application to be high, the speed is quick, stable high characteristic.
Reference
[1] TMS320C3x User `s Guide Texas Instruments 1998
[2] The versatile OrCAD circuit diagram designs Capture V9 Zhang Yihe to write the Chinese Railroad Publishing house
[3] The versatile OrCAD circuit wafer designs Layout Plus V9 Zhang Yihe to write the Chinese Railroad Publishing house
[4] Electrical energy measurement foundation China Measurement Publishing house Zhang Youshun and so on writes
