CN215575328U - Novel transformer voltage phase difference measuring instrument circuit design - Google Patents

Abstract

The utility model relates to a novel circuit design scheme of a transformer voltage phase difference measuring instrument, which is suitable for measuring voltages, currents and phase differences at two ends of a transformer. The circuit design scheme comprises a power supply circuit, a charging circuit, an STM32F407 minimum system, an SRAM storage circuit, a display screen communication circuit and a voltage-current measuring circuit. Sinusoidal current signals of two sides of the transformer passing through the zero-crossing detection circuit are acquired step by step through the STM32, the time interval of two acquisition is calculated, and the phase difference of the two times of the transformer can be obtained. The utility model has the beneficial effects that: and collecting the voltage and current values at two sides of the transformer by adopting current and voltage transformers. And the phase difference of the two sides of the transformer is measured in a step-by-step mode, so that the influences of the volume and the arrangement environment of the transformer are avoided in use.

Description

Novel transformer voltage phase difference measuring instrument circuit design

Technical Field

The utility model relates to the technical field of electronics, in particular to a novel circuit design of a transformer voltage phase difference measuring instrument.

Background

With the increasing complexity of integrated circuits, the number of devices contained in a single chip increases, the structure of the integrated circuit is changed from a simple function to a function with more and more complex functions, and the design of the system is continuously developed towards lightness, thinness and smallness. The SoC is used as a system-level integrated circuit and can realize the functions of signal acquisition, conversion, processing, I/O and the like on a single silicon chip. Therefore, how to design a new transformer voltage phase difference measuring instrument through the SoC is a trend.

SUMMERY OF THE UTILITY MODEL

The utility model mainly provides a novel circuit design of a transformer voltage phase difference measuring instrument, and the specific scheme is as follows:

the utility model provides a circuit design scheme of a novel transformer voltage phase difference measuring instrument, which is suitable for measuring voltage, current and phase difference at two ends of a transformer. The circuit design scheme comprises a power supply circuit, a charging circuit, an STM32F407 minimum system, an SRAM storage circuit, a display screen communication circuit and a voltage-current measuring circuit. The power supply circuit comprises 12V conversion

5V and 5V are converted into 3.3V, so that the power supply of the whole circuit is realized; the charging circuit is used for charging a 12V lithium battery; the STM32F407 minimum system comprises a crystal oscillator circuit, a key circuit and a serial port-to-USB circuit, wherein the crystal oscillator is used as a clock of the system, the key is used for a user to operate the system, and the serial port-to-USB circuit is used for debugging; the SRAM memory circuit is used for storing measurement data; the display screen communication circuit is a UART-to-485 converter and is used for communication between the system and the display screen; the voltage-current measuring circuit comprises a clamp type current transformer, a voltage transformer, an AD637 effective value detecting circuit and a zero-crossing detecting circuit, wherein the clamp type current transformer, the voltage transformer and the AD637 effective value detecting circuit are connected with a power supply through a power supply lineThe voltage transformer is used for converting high-voltage and high-current signals on one side of the transformer into measurable signals of the single chip microcomputer, the AD637 effective value detection circuit is used for calculating effective values of voltage and current, and the zero-crossing detection circuit is used for detecting zero-crossing time of sinusoidal signals.

Further, the circuit for converting 12V into 5V is used for supplying power to the AD637 effective value detection circuit, a self-recovery fuse is added, and damage of a large current to a system is prevented. 5V to 3.3V is used to power the STM32F407 minimum system.

Further, the charging circuit may employ CN3768 charging management IC, which can achieve a maximum charging current of 4A.

Further, an active crystal oscillator of 24MHz is adopted in the STM32F407 minimum system, so that the clock of the system is more accurate.

Furthermore, the USB-to-serial port circuit can adopt a chip CH340 and a 12MHz passive crystal oscillator to realize the communication between a computer and a system.

Further, the SRAM can adopt IS62WV51216 for storing measurement data and IS driven by an FSMC module of an STM32F407 minimum system.

Furthermore, a display screen communication circuit, namely a UART-to-485 circuit, can use a chip MAX485, and communication between the STM32F407 minimum system and the display screen is realized.

Further, the clamp type current transformer and the voltage transformer convert large current and large voltage signals into alternating current milliampere signals, and the alternating current signals are converted into voltage signals through a sampling resistor to be collected by an STM32F407 minimum system. On the basis, a self-recovery fuse is added at the joint of the voltage transformer, so that large current is prevented from flowing into the system.

Furthermore, a UA741 operational amplifier is adopted in the zero-crossing detection circuit, the acquired voltage signal is compared with the ground, a 3.3V voltage-stabilizing tube is added on the output side for protection, and the conversion from an alternating current signal to a 3.3V square wave signal is realized.

Furthermore, the circuit design scheme adopts a step-by-step measurement method when measuring the phase difference between two ends of the transformer, so that the influence of the volume of the transformer, namely the environmental arrangement is eliminated.

The utility model has the beneficial effects that: the novel transformer voltage phase difference measuring instrument adopts the current and voltage transformers to collect the voltage and current values at two sides of the transformer, and then calculates the phase difference of two lines of signals with the same frequency through the zero-crossing comparator. And the measurement mode of the phase difference data is a step mode, so that the influence of the volume of equipment and the environmental arrangement on the measurement is overcome.

Drawings

FIG. 1 is a block diagram of a meter circuit design.

Fig. 2 is a power supply circuit diagram.

Fig. 3 is a charging circuit diagram.

FIG. 4 is a serial to USB circuit diagram.

Fig. 5 is a serial port to 485 circuit diagram.

Fig. 6 is an AD 637-effective-value electrical measurement circuit diagram.

Fig. 7 is a zero-crossing detection circuit diagram.

Detailed Description

In order to better understand the technical scheme of the utility model, the following embodiment is further described in detail, and an application example is combined to illustrate the specific embodiment and test the performance of the scheme of the utility model.

The utility model provides a circuit design scheme of a novel transformer voltage phase difference measuring instrument, which is suitable for measuring voltage, current and phase difference at two ends of a transformer.

As shown in fig. 1 to 7, the circuit design scheme includes a power supply circuit, a charging circuit, an STM32F407 minimum system, an SRAM memory circuit, a display screen communication circuit, and a voltage-current measurement circuit.

In a preferred embodiment, 12V voltage is converted into 5V by WRE1205, and on the basis, 5V voltage is reduced to 3.3V by using a linear voltage regulator ASM1117-3.3, so that the power supply of the whole system is realized.

In a preferred embodiment, a maximum 4A charging current for a 12V battery is achieved using CN3768 in combination with P-channel MOS transistors.

In a preferred embodiment, the conversion between serial and USB signals is implemented using CH340, and the serial download of the hex program is implemented using two PNP transistors.

In a preferred embodiment, four AD637 are used to calculate the effective values of sinusoidal single-phase voltage and three-phase current respectively, and are collected by an ADC.

In a preferred embodiment, a zero-crossing comparator is built by using the operational amplifier UA741, and outputs 3.3V when the voltage is greater than zero and 0V when the voltage is less than zero.

In a preferred embodiment, the input capturing function of the STM32 is used to collect the rising edge and the falling edge of the square wave signal output by the UA741, and the time interval between two times of collection is determined by collecting the sinusoidal current signals passing through the zero-crossing detection circuit on two sides of the transformer step by step, so as to calculate the phase difference between two times of the transformer.

It will be appreciated by those skilled in the art that the present invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. The embodiments disclosed above are therefore to be considered in all respects as illustrative and not restrictive. All changes which come within the scope of or equivalence to the utility model are intended to be embraced therein.

Claims (8)

1. A novel transformer voltage phase difference measuring instrument circuit design is characterized in that: the method is suitable for measuring the voltage, the current and the phase difference of two ends of the transformer; the circuit design comprises a power supply circuit, a charging circuit, an STM32F407 minimum system, an SRAM storage circuit, a display screen communication circuit and a voltage-current measuring circuit;

the power supply circuit comprises 12V to +/-5V and 5V to 3.3V, and power supply of the whole circuit is realized; the charging circuit is used for charging a 12V lithium battery;

the STM32F407 minimum system comprises a crystal oscillator circuit, a key circuit and a serial port-to-USB circuit, wherein the crystal oscillator is used as a clock of the system, the key is used for a user to operate the system, and the serial port-to-USB circuit is used for debugging;

the SRAM memory circuit is used for storing measurement data;

the display screen communication circuit is a UART-to-485 converter and is used for communication between the system and the display screen; the voltage-current measuring circuit comprises a clamp type current transformer, a voltage transformer, an AD637 effective value detecting circuit and a zero-crossing detecting circuit, wherein the clamp type current transformer and the voltage transformer are used for converting high-voltage and high-current signals on one side of a transformer into measurable signals of a single chip microcomputer, the AD637 effective value detecting circuit is used for calculating effective values of voltage and current, and the zero-crossing detecting circuit is used for detecting zero-crossing time of sinusoidal signals.

2. The novel transformer voltage phase difference measuring instrument circuit design according to claim 1, characterized in that: the power supply circuit is a 12V to +/-5V circuit and is used for supplying power to the AD637 effective value detection circuit, a self-recovery fuse is added, and damage of a large current to a system is prevented; 5V to 3.3V is used to power the STM32F407 minimum system.

3. The novel transformer voltage phase difference measuring instrument circuit design according to claim 1, characterized in that: the charging circuit adopts CN3768 charging management IC, and can realize the maximum charging current of 4A.

4. The novel transformer voltage phase difference measuring instrument circuit design according to claim 1, characterized in that: the STM32F407 minimum system adopts a 24MHz active crystal oscillator, so that the clock of the system is more accurate.

5. The novel transformer voltage phase difference measuring instrument circuit design according to claim 1, characterized in that: the SRAM adopts IS62WV51216 for storing measurement data and IS driven by an FSMC module of an STM32F407 minimum system.

6. The novel transformer voltage phase difference measuring instrument circuit design according to claim 1, characterized in that: the communication circuit of the display screen, namely the UART-to-485 circuit, can use the chip MAX485, has realized the communication of STM32F407 minimum system and display screen.

7. The novel transformer voltage phase difference measuring instrument circuit design according to claim 1, characterized in that: voltage-current sampling circuit: the clamp type current transformer and the voltage transformer convert large current and large voltage signals into alternating current milliampere signals, and the alternating current signals are converted into voltage signals through a sampling resistor to be collected by an STM32F407 minimum system; on the basis, a self-recovery fuse is added at the joint of the voltage transformer, so that large current is prevented from flowing into the system.

8. The novel transformer voltage phase difference measuring instrument circuit design according to claim 1, characterized in that: a UA741 operational amplifier is adopted in the zero-crossing detection circuit, the acquired voltage signal is compared with the ground, a 3.3V voltage-stabilizing tube is added on the output side for protection, and the conversion from an alternating current signal to a 3.3V square wave signal is realized.

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