CN205450098U - Current transformer module - Google Patents

Abstract

The utility model discloses a current transformer module comprising a first resistor, a second resistor, a third resistor, a fourth resistor, a first capacitor, a second capacitor, a first diode and a transformer, the first transformer of the transformer The output terminal is connected to the second output terminal of the transformer through the fourth resistor, the first output terminal of the transformer is connected to the positive terminal of the first diode, and the negative terminal of the first diode is connected to the The positive terminal of the second capacitor is connected to the second output terminal of the transformer through the second resistor, and the positive terminal of the second capacitor is connected to the output port through the first resistor. The utility model can detect the working current of the compressor in real time by being connected with the compressor and the controller, convert it into a voltage and transmit it to the controller, facilitate the calculation of the working current of the compressor, effectively improve the detection accuracy and reduce errors. The utility model can be widely used in compressor protection.

Description

A current transformer module

technical field

The utility model relates to the technical field of electronic circuits, in particular to a current transformer module.

Background technique

As the core component of the heat pump system, the protection of the compressor is particularly important; the traditional compressor protection usually uses a high and low pressure protection switch, and its control method is to disconnect the high and low pressure protection when the system pressure reaches the high and low pressure protection value. Switch and stop the compressor for protection, but this control method will have such problems: because the detection accuracy through the high and low voltage protection switch is not high, and the error is large, it often does not achieve a good protection effect.

Utility model content

In order to solve the above technical problems, the purpose of this utility model is to provide a current transformer module with simple structure and convenient and accurate current calculation.

The technical scheme that the utility model takes is:

A current transformer module, comprising a first resistor, a second resistor, a third resistor, a fourth resistor, a first capacitor, a second capacitor, a first diode and a transformer, the first output terminal of the transformer passes through the first The four resistors are connected to the second output terminal of the transformer, the first output terminal of the transformer is connected to the positive terminal of the first diode, and the negative terminal of the first diode is connected to the second capacitor through the third resistor. positive terminal, the positive terminal of the second capacitor is connected to the second output terminal of the transformer through the second resistor, the positive terminal of the second capacitor is connected to the output port through the first resistor, and the output port is connected through the first capacitor to the second output terminal of the transformer, and the negative terminal of the second capacitor is connected to the second output terminal of the transformer.

As a further improvement of the current transformer module, it also includes a second diode, the positive terminal of the second capacitor is connected to the positive terminal of the second diode, and the negative terminal of the second diode is connected to the positive terminal of the second diode. Connect the terminal to the protection voltage terminal.

As a further improvement of the current transformer module, the second capacitor is an electrolytic capacitor.

As a further improvement of the current transformer module, the output port is connected to a controller.

As a further improvement of the current transformer module, the input end of the transformer is connected to any phase of the three-phase compressor.

The beneficial effects of the utility model are:

A current transformer module of the utility model has a simple structure, can be connected with a compressor and a controller, thereby real-time detecting the working current of the compressor and converting it into a voltage to be transmitted to the controller, which facilitates the calculation of the working current of the compressor and can effectively Improve detection accuracy and reduce errors.

Description of drawings

The specific embodiment of the utility model will be further described below in conjunction with accompanying drawing:

Fig. 1 is a schematic circuit diagram of a current transformer module of the present invention.

detailed description

Referring to Fig. 1, a current transformer module of the present invention includes a first resistor R1, a second resistor R2, a third resistor R3, a fourth resistor R4, a first capacitor C1, a second capacitor C2, a first diode D1 and a transformer CT, the first output terminal of the transformer CT is connected to the second output terminal of the transformer CT through the fourth resistor R4, the first output terminal of the transformer CT is connected to the positive terminal of the first diode D1, The negative terminal of the first diode D1 is connected to the positive terminal of the second capacitor C2 through the third resistor R3, and the positive terminal of the second capacitor C2 is connected to the second output terminal of the transformer CT through the second resistor R2, The positive end of the second capacitor C2 is connected to the output port through the first resistor R1, the output port is connected to the second output end of the transformer CT through the first capacitor C1, and the negative end of the second capacitor C2 is connected to the transformer The second output end of the CT, the second output end of the transformer CT is connected to the ground.

As a further preferred embodiment, it also includes a second diode D2, the positive terminal of the second capacitor C2 is connected to the positive terminal of the second diode D2, and the negative terminal of the second diode D2 is connected to Protect the voltage terminals. The second diode D2 is used to ensure that the analog output to the chip port is not greater than 5V, so as not to damage the chip.

As a further preferred implementation manner, the second capacitor C2 is an electrolytic capacitor.

As a further preferred embodiment, the output port is connected to a controller.

As a further preferred implementation manner, the input end of the transformer CT is connected to any phase of the three-phase compressor.

In the utility model, the transformer CTCT is used to convert the AC current required to be detected into a small current (AC) that can be sampled; the fourth resistor R4R4 is used to convert the converted small current into a voltage (AC); the first two The pole tube D1D1 is used to rectify the half-wave converted AC voltage into a DC voltage; the second capacitor C2C2 is used to smooth the rectified DC voltage waveform, and input it to the chip after voltage division; the second resistor R2R2 and the third resistor R3R3 are used for As a voltage divider resistor, it is mainly used to adjust the parameters of A/D conversion and directly determine the A/D parameters input to the chip port; the first resistor R1R1 and the first capacitor C1C1 are used to form an RC filter circuit. Since the input current required by the A/D port of the controller is extremely small, adding it between the chip and the input will not cause a voltage drop, so it will not affect the accuracy of sampling. However, the output signal of the current detection circuit is filtered to prevent high-frequency interference.

A compressor protection control method using the module, comprising the following steps:

A. Connect the current transformer module with the compressor, and the current signal of the compressor is converted into a voltage signal by the current transformer module and output to the controller;

B. The controller calculates the working current value according to the collected voltage signal;

C. Detect the current signal output by the compressor to obtain the actual current detection value;

D. According to the working current value and the actual current detection value, both are calibrated to obtain the real working current value;

E. Determine whether the real working current value is greater than the preset protection current value, if so, control the compressor to stop protection; otherwise, maintain the current working state.

Further as a preferred embodiment, it also includes:

F. When the compressor is in the stop state, judge whether the real working current value is less than the preset starting current value, if so, control the compressor to start working; otherwise, maintain the current stop state.

Further as a preferred embodiment, the calculation formula of the working current value in the step B is:

;

Among them, I represents the working current value, R2 represents the resistance value of the second resistor R2, R3 represents the resistance value of the third resistor R3, R4 represents the resistance value of the fourth resistor R4, Vout represents the collected voltage signal, and N represents the voltage in the transformer CT Turns ratio of input to output.

Further as a preferred embodiment, the step D includes:

D1. Determine whether the difference between the working current value and the actual current detection value is within the preset error range, if so, take the working current value as the real working current value; otherwise, execute step D2;

D2. Use a high-precision ammeter to re-test the current of the compressor to obtain the real working current value.

In a specific embodiment of the utility model, the detection accuracy of the current transformer module is 0.1A, and the detection range is 0-25A.

In the utility model, the detected current I (compressor operating current) and the current Iout output to the above circuit are in direct proportion: I=N*Iout; N is the turns ratio of input and output, which is a constant, and different currents There are also differences in transformers and N.

The AC current Iout flows into the circuit, and the effective value of the current is obtained after half-wave rectification by the first diode D1, which is finally converted into a voltage Vout and output to the controller; the first resistor R1, the first capacitor C1 and the second capacitor C2 form a filter The purpose of the circuit is to make the DC signal input to the control smoother and prevent high-frequency interference; the second diode D2 ensures that the voltage signal input to the controller is less than 5V to ensure that the control chip is not damaged.

The voltage UA=Iout*R4 of point A to ground, since the fourth resistor R4 and the first diode D1, the third resistor R3, and the second resistor R2 are connected in parallel, then UB=UC*[R4/(R4+R5 )].

According to the diode half-wave rectification, the voltage at point C UC= *UA-0.5, where 0.5 is the voltage drop across the diode.

Based on the above formulas, the working current .

The controller collects the Vout voltage signal, and then calculates the working current through the formula. However, due to a certain error in the resistance (accuracy: 1%) in the circuit, there will be a certain deviation between the calculated current and the actual current. When the working current value When the difference with the actual current detection value exceeds the preset error range, in order to make the measurement result more accurate, it is necessary to use a higher-precision ammeter (accuracy 0.01A) to calibrate it and compensate the formula to obtain accurate compressor operating current.

It can be seen from the above that,

A current transformer module of the utility model can be connected with the compressor and the controller, so as to detect the working current of the compressor in real time and convert it into voltage and transmit it to the controller, which facilitates the calculation of the working current of the compressor and can effectively improve the detection accuracy ,reduce mistakes.

The above is a specific description of the preferred implementation of the present utility model, but the utility model creation is not limited to the described embodiments, and those skilled in the art can also make various equivalents without violating the spirit of the present utility model. Modifications or replacements, these equivalent modifications or replacements are all included within the scope defined by the claims of the present application.

Claims (5)

1. a current transformer module, it is characterized in that: include the first resistance, second resistance, 3rd resistance, 4th resistance, first electric capacity, second electric capacity, first diode and transformator, first outfan of described transformator is connected to the second outfan of transformator by the 4th resistance, first outfan of described transformator is connected to the positive terminal of the first diode, the negative pole end of described first diode is connected to the positive terminal of the second electric capacity by the 3rd resistance, the positive terminal of described second electric capacity is connected to the second outfan of transformator by the second resistance, the positive terminal of described second electric capacity is connected to output port by the first resistance, described output port is connected to the second outfan of transformator by the first electric capacity, the negative pole end of described second electric capacity is connected to the second outfan of transformator.

A kind of current transformer module the most according to claim 1, it is characterised in that: also including the second diode, the positive terminal of described second electric capacity is connected to the positive terminal of the second diode, and the negative pole end of described second diode is connected to protect voltage end.

A kind of current transformer module the most according to claim 2, it is characterised in that: described second electric capacity is electrochemical capacitor.

A kind of current transformer module the most according to claim 3, it is characterised in that: described output port is connected to controller.

A kind of current transformer module the most according to claim 4, it is characterised in that: any one phase that the input of described transformator is connected in three-phase compressor.