High-precision rotary transformer excitation output circuit

Abstract

According to the high-precision rotary transformer excitation output circuit provided by the utility model, high-frequency signals are filtered out from excitation signals output by the rotary transformer decoding chip through the RC low-pass filter circuit, so that the excitation signals output by the rotary transformer decoding chip are closer to low-frequency parts of original signals, and the integrity of the signals is ensured while filtering is carried out. And the amplitude of the excitation signal is enhanced through the reverse amplification circuit, and then the voltage following circuit provides impedance matching, so that the loss of the excitation signal in the transmission process is reduced. And then the excitation signal is amplified through a power amplification circuit, and the driving force is improved. High-frequency signals of the amplified excitation signals are filtered out through the anti-interference filter circuit, noise is reduced, the excitation signals are input into the induction coil, the induction coil and the motor rotor form electromagnetic induction, and therefore the rotation angle of the motor rotor is collected, and better stability and higher precision are achieved.

Description

TECHNICAL FIELD

[0001] The utility model relates to the field of power electronics, especially relates to a high-precision rotary transformer excitation output circuit. BACKGROUND

[0002] Under the impetus of the national new energy electric vehicle industry development strategy, the domestic new energy electric vehicle industry develops rapidly, and the mechanical type gradually develops towards electrification and electronization, and motor drive becomes an inevitable power mode; the rotary transformer is an electromagnetic sensor that converts mechanical rotation angle into electrical signal, and realizes the conversion and transmission of angle information by measuring the relative position between the rotor and the stator, and is widely used in the precise control of motor rotation, and provides a reliable solution for various systems requiring accurate position control.

[0003] In actual conditions, the rotary transformer circuit working environment is complex, the excitation signal generated by the rotary transformer decoding chip has more noise generated by high-frequency interference, and the quality of the excitation signal generated by the rotary transformer chip is not high, and improper processing of the rotary transformer excitation signal will cause the controller to collect the motor rotor rotation angle position to deviate, resulting in that the motor rotation does not match the actual control or even cannot rotate.

[0004] The existing excitation output circuit outputs an excitation signal through a special chip as an excitation source, amplifies the excitation signal through an operational amplifier, and then connects a push-pull power amplifier to power amplify the signal, and the existing technology has the following disadvantages: 1. Poor anti-interference ability: in a complex environment, the rotary transformer excitation circuit is easily affected by external electromagnetic interference, resulting in distortion of the excitation signal, thereby affecting the accuracy of the position information detected by the rotary transformer. 2. Insufficient precision: due to the improper design of the circuit filter, the existing rotary transformer excitation circuit may have certain errors in the signal transmission and processing process, resulting in low precision of the output signal. UTILITY MODEL CONTENTS

[0005] In order to solve the above problems, the utility model aims at providing a high-precision rotary transformer excitation output circuit, which solves the problems of insufficient excitation signal precision and poor anti-interference ability through a low-pass filter circuit, a reverse amplification circuit, a voltage follower circuit and a power amplifier circuit.

[0006] The utility model realizes the following technical solutions:

[0007] The application discloses a high-precision rotary transformer excitation output circuit which comprises two groups of RC low-pass filter circuits connected in sequence, reverse amplification circuits, voltage follower circuits and power amplification circuits, and the output ends of the two groups of power amplification circuits are further connected with anti-interference filter circuits; wherein the two groups of RC low-pass filter circuits are connected with rotary transformer decoding chips respectively and used for inputting positive and negative excitation signals of the rotary transformer decoding chips; the output end of the anti-interference filter circuit is connected with an induction coil; and the induction coil forms electromagnetic induction with a motor rotor.

[0008] Further, the RC low-pass filter circuit comprises an eighth resistor and a third capacitor connected in series with the output end of the rotary transformer decoding chip, and the other end of the third capacitor is connected with the reverse amplification circuit.

[0009] Further, the reverse amplification circuit comprises a first amplifier, the RC low-pass filter circuit is connected with the inverting input end of the first amplifier, the non-inverting input end of the first amplifier is connected with a reference voltage, the second capacitor and the sixth resistor are connected in parallel between the inverting input end and the output end of the first amplifier; and the output end of the first amplifier is connected with the voltage follower circuit.

[0010] Further, the voltage follower circuit comprises a second amplifier, the output end of the reverse amplification circuit is connected with the non-inverting input end of the second amplifier, and the inverting input end and the output end of the second amplifier are both connected with the power amplification circuit.

[0011] Further, the power amplification circuit comprises a current detection resistor group, a first push-pull triode and a fourth push-pull triode; the emitters of the first push-pull triode and the fourth push-pull triode are connected with two ends of the current detection resistor group respectively.

[0012] Further, the power amplification circuit further comprises a second triode and a third triode connected with the emitters, the base of the second triode is connected with the emitter of the first push-pull triode, the collector of the second triode is connected with the base of the first push-pull triode; the base of the third triode is connected with the emitter of the fourth push-pull triode, and the collector of the third triode is connected with the base of the fourth push-pull triode.

[0013] Further, the current detection resistor group comprises a third resistor and a fourth resistor connected in parallel, and the fourth resistor and the fourth resistor are connected in series with a tenth resistor and an eleventh resistor connected in parallel; the common end of the fourth resistor and the eleventh resistor is connected with the anti-interference filter circuit.

[0014] Further, the anti-interference filter circuit comprises a common-mode inductor and a bypass capacitor group, input ends of the common-mode inductor are connected with output ends of two groups of the power amplifier circuit respectively, and the bypass capacitor group comprises a ninth capacitor and a tenth capacitor connected with output ends of the common-mode inductor respectively, and the other ends of the ninth capacitor and the tenth capacitor are grounded.

[0015] Further, the anti-interference filter circuit comprises a common-mode inductor and a bypass capacitor group, input ends of the common-mode inductor are connected with output ends of two groups of the power amplifier circuit respectively, and the bypass capacitor group comprises a ninth capacitor and a tenth capacitor connected with output ends of the common-mode inductor respectively, and the other ends of the ninth capacitor and the tenth capacitor are grounded.

[0016] Further, the anti-interference filter circuit comprises a common-mode inductor and a bypass capacitor group, input ends of the common-mode inductor are connected with output ends of two groups of the power amplifier circuit respectively, and the bypass capacitor group comprises a ninth capacitor and a tenth capacitor connected with output ends of the common-mode inductor respectively, and the other ends of the ninth capacitor and the tenth capacitor are grounded.

[0017] Compared with the prior art, the technical scheme and beneficial effects of the utility model are as follows:

[0018] (1) The rotary variable differential transformer (RVDT) excitation output circuit of the utility model filters out high-frequency signals in the excitation signal through the RC low-pass filter circuit. The RVDT decoding chip outputs an excitation signal closer to the low-frequency part of the original signal, ensuring the integrity of the signal while filtering. Then, the amplitude of the excitation signal is enhanced through the reverse amplification circuit, and then the voltage follower circuit provides impedance matching to reduce the loss of the excitation signal in the transmission process. Subsequently, the power amplifier circuit amplifies the excitation signal and improves the driving force. The amplified excitation signal is filtered to reduce noise through the anti-interference filter circuit, and then input to the induction coil. The induction coil and the motor rotor form electromagnetic induction, thereby collecting the rotation angle of the motor rotor to ensure the accuracy of the RVDT excitation signal.

[0019] (2) The utility model sets a voltage follower circuit between the reverse amplification circuit and the power amplifier circuit. The voltage follower circuit has high input impedance and low output impedance, which can effectively provide impedance matching between the RVDT output and the subsequent circuit, reducing the loss of the signal in the transmission process. At the same time, the voltage follower circuit can well isolate the front and rear circuits, preventing the rear circuit from affecting the performance of the front circuit.

[0020] (3) The voltage follower circuit of the utility model acts as a buffer to prevent signal attenuation or distortion during transmission. It can also protect sensitive subsequent circuits from high voltage or current surges from the RVDT decoding chip, reduce noise and interference caused by resistors, wires, etc. in the circuit, and improve the signal-to-noise ratio of the signal. BRIEF DESCRIPTION OF DRAWINGS

[0021] Figure 1 is a high-precision RVDT excitation output circuit principle block diagram provided by the utility model embodiment;

[0022] Figure 2 The utility model discloses a circuit principle diagram of high accuracy's rotary transformer excitation output circuit. DETAILED DESCRIPTION

[0023] In order to make the purpose, technical scheme and advantage of the utility model embodiment more clear, below, the technical scheme in the utility model embodiment will be clearly and completely described with the drawings in the utility model embodiment, obviously, the described embodiment is a part of the utility model embodiment, instead of all the embodiment. It should be understood that the specific embodiment described here is only used to explain the utility model, and is not used to limit the utility model. Based on the embodiment in the utility model, all other embodiments obtained by the person skilled in the art without creative labor are within the scope of the utility model protection.

[0024] Reference Figure 1 A kind of high accuracy's rotary transformer excitation output circuit, including including two groups of RC low pass filter circuit connected in turn, reverse amplification circuit, voltage follower circuit, power amplifier circuit, the output end of two groups of power amplifier circuit is also connected with anti-interference filter circuit, anti-interference filter circuit is also connected with anti-static circuit.Two groups of RC low pass filter circuit are connected with rotary transformer decoding chip respectively, for accessing the positive and negative excitation signal of rotary transformer decoding chip, the output end of anti-static circuit and motor rotor form electromagnetic induction.

[0025] Excitation signal output by rotary transformer decoding chip is filtered by RC low pass filter circuit to filter out high frequency signal, so that excitation signal output by rotary transformer decoding chip is closer to low frequency part of original signal, guarantee signal integrity while filtering.Again, reverse amplification circuit enhances the amplitude of excitation signal, then voltage follower circuit provides impedance matching, reduces the loss of excitation signal in transmission process. Then, excitation signal is amplified by power amplifier circuit and driving force is improved. After amplification, excitation signal is filtered by anti-interference filter circuit to filter out high frequency signal and reduce noise, is input to induction coil, induction coil and motor rotor form electromagnetic induction, thereby the rotation angle of motor rotor is collected. Rotary transformer excitation signal through the circuit of the application has better stability and higher precision.

[0026] In the application, RC low pass filter circuit, reverse amplification circuit, voltage follower circuit, power amplifier circuit are all provided with same two groups, only one group is taken as an example in the following embodiment.

[0027] The RC low-pass filter circuit comprises a resistor R8 and a capacitor C3 connected in series with the output terminal of the resolver decoding chip, and the other terminal of the capacitor C3 is connected with the reverse amplification circuit. The RC low-pass filter circuit filters out high-frequency signals in the circuit and only allows low-frequency signals to pass through, so that the output excitation signal is closer to the low-frequency part of the original signal, and the integrity of the excitation signal is ensured while filtering.

[0028] The reverse amplification circuit comprises an amplifier U1A, the capacitor C3 is connected with the inverting input terminal of the amplifier U1A, the non-inverting input terminal of the amplifier U1A is connected with a reference voltage 6V, and the capacitor C2 and the resistor R6 are connected in parallel between the inverting input terminal and the output terminal of the amplifier U1A; the output terminal of the amplifier U1A is connected with the voltage follower circuit. The excitation signal output by the resolver decoding chip is usually weak, and the amplitude of the excitation signal can be enhanced through the reverse amplification circuit, so as to reduce the possibility of clipping and distortion of the excitation signal after amplification. At the same time, the reverse amplification circuit can invert the phase of the excitation signal by 180°, which is convenient for realizing accurate control in a closed-loop control system by the phase difference between the resolver output signal and the reference signal.

[0029] The voltage follower circuit comprises an amplifier U1B, the output terminal of the amplifier U1A is connected with the non-inverting input terminal of the amplifier U1B, and the inverting input terminal and the output terminal of the amplifier U1B are both connected with the power amplification circuit. The amplifier U1B is powered by a 12V external power supply, and the capacitor C1 is further connected between the 12V external power supply and the amplifier U1B, and the other terminal of the capacitor C1 is grounded. Since the impedance of the excitation signal output by the resolver decoding chip is usually high, and the subsequent processing circuit may require a lower input impedance. The voltage follower circuit has the characteristics of high input impedance and low output impedance, which can effectively provide impedance matching between the resolver output and the subsequent circuit, reduce the loss of the signal in the transmission process. At the same time, the voltage follower circuit can well isolate the front and rear circuits, prevent the rear circuit from affecting the performance of the front circuit. As a buffer, prevent the signal from being attenuated or distorted during transmission. And can protect the sensitive subsequent circuit from the high voltage or current impact from the resolver decoding chip, reduce the noise and interference caused by the resistance, wire, etc. in the circuit, and improve the signal-to-noise ratio of the signal.

[0030] The power amplification circuit comprises a current detection resistor group, a push-pull transistor Q1 and a push-pull transistor Q4, the emitter of the push-pull transistor Q1 and the emitter of the push-pull transistor Q4 are respectively connected to the two ends of the current detection resistor group. The current detection resistor group comprises resistors R3 and R4 connected in parallel, resistors R10 and R11 connected in parallel, and the two are connected in series. The common terminal of the resistor R4 and the resistor R11 is connected with the anti-interference filter circuit. The collector of the push-pull transistor Q4 is grounded, and the collector of the push-pull transistor Q1 is connected with an external 12V power supply.

[0031] The push-pull circuit composed of the push-pull triode Q1 and the push-pull triode Q4 controls the turn-on and turn-off of the Q1 and Q2 to amplify the current of the excitation signal to the rated working current of the rotary transformer, thereby improving the output driving capability of the excitation signal. The current detection resistor group is used to turn off the push-pull triode Q1 and the push-pull triode Q4 when overcurrent occurs in the circuit, thereby protecting the push-pull triode Q1 and the push-pull triode Q4.

[0032] The power amplifier circuit further comprises the emitter-connected triode Q2 and the triode Q3, the base of the triode Q2 is connected with the emitter of the push-pull triode Q1, and the collector of the triode Q2 is connected with the base of the push-pull triode Q1; the base of the triode Q3 is connected with the emitter of the push-pull triode Q4, and the collector of the triode Q3 is connected with the base of the push-pull triode Q4.

[0033] The base and the collector of the push-pull triode Q4 are connected with the resistor R17, the base and the collector of the push-pull triode Q1 are connected with the resistor R1, the power amplifier circuit further comprises the diode group D1, the diode group D1 comprises two diodes connected in series, a current-limiting resistor is arranged between the cathode of the diode group D1 and the common terminal of the triode Q3 and the push-pull triode Q4, and a current-limiting resistor R2 is arranged between the anode of the diode group D1 and the common terminal of the triode Q2 and the push-pull triode Q1, the output terminal of the amplifier U1B is connected with the common terminal of the two diodes of the diode group D1, and the non-inverting input terminal of the amplifier U1B is connected with the common terminal of the triode Q2 and the triode Q3.

[0034] When the rotary transformer excitation circuit is subjected to a high-voltage impact, the negative feedback voltage of the amplifier U1B is increased, and the output is low, so that the base of the push-pull triode Q1 is low, the push-pull triode Q1 is cut off, and the power supply is quickly turned off, thereby protecting the sensitive subsequent circuit from the high-voltage impact from the rotary transformer.

[0035] Meanwhile, when a short circuit or a large current impact occurs in the rotary transformer excitation circuit, the resistors R3, R4, R10 and R11 detect overcurrent, the triode Q2 and the triode Q3 are in the conductive state, the triode Q2 and the triode Q3 play a current-limiting role, the emitter voltage of the push-pull triode Q1 is raised, and the push-pull triode Q1 is turned off; at the same time, the base voltage of the push-pull triode Q4 is higher than the emitter voltage, and the push-pull triode Q4 is turned off. The output current is reduced to close to zero, and the device is prevented from being seriously heated due to excessive current. The controller enters the protection state and stops outputting the excitation signal.

[0036] The anti-interference filter circuit comprises a common-mode inductor L1 and a bypass capacitor group. The input terminals of the common-mode inductor are connected with the output terminals of the two power amplifier circuits respectively, the bypass capacitor group comprises the capacitor C9 and the capacitor C10 connected with the output terminal of the common-mode inductor L1 respectively, and the other ends of the capacitor C9 and the capacitor C10 are grounded.

[0037] Common mode inductance L1 is used to suppress common mode interference, which exists simultaneously between signal lines and ground lines and is in the same direction. Common mode inductance L1 presents high impedance to common mode signals and low impedance to differential mode signals, thus not significantly affecting normal differential mode signal transmission. The bypass capacitor group (usually ceramic capacitor) is used to provide a low impedance path to high frequency interference signals, thereby bypassing interference signals from the signal line to the ground, reducing noise in the circuit.

[0038] The anti-static circuit is further arranged between the anti-interference filter circuit and the induction coil, and the anti-static circuit comprises an ESD static protection tube D2, two same ends of the ESD static protection tube D2 are connected with output ends of the common mode inductance L1 respectively, and the other two same ends of the ESD static protection tube D2 are grounded. By arranging the ESD static protection tube D2, the overall reliability of the electronic equipment is significantly improved, the failure rate is reduced, and the service life of the equipment is prolonged.

[0039] The above description shows and describes the preferred embodiments of the utility model, and it should be understood that the utility model is not limited to the form disclosed herein, and should not be considered as excluding other embodiments, but can be used in various other combinations, modifications and environments, and can be modified within the scope of the utility model concept disclosed herein by the above teaching or related technical or knowledge. The modification and change made by the person skilled in the art without departing from the spirit and scope of the utility model should be within the protection scope of the utility model claims attached herein.

Claims

1. A high-precision resolver excitation output circuit, characterized in that, The anti-interference filter circuit is connected to the output end of the two groups of power amplifier circuits. The RC low-pass filter circuit includes an eighth resistor and a third capacitor connected in series with the output end of the resolver decoding chip.

2. The high-precision rotary transducer excitation output circuit according to claim 1, characterized in that, The reverse amplification circuit includes a first amplifier, the RC low-pass filter circuit is connected to the inverting input end of the first amplifier, the non-inverting input end of the first amplifier is connected to a reference voltage, and the second capacitor and the sixth resistor are connected in parallel between the inverting input end and the output end of the first amplifier; the output end of the first amplifier is connected to the voltage follower circuit.

3. The high-precision rotary transducer excitation output circuit according to claim 1, characterized in that, The voltage follower circuit includes a second amplifier, the output end of the reverse amplification circuit is connected to the non-inverting input end of the second amplifier, and the inverting input end and the output end of the second amplifier are both connected to the power amplifier circuit.

4. The high-precision rotary transducer excitation output circuit according to claim 1, characterized in that, The power amplifier circuit includes a current detection resistor group, a first push-pull triode and a fourth push-pull triode; the emitters of the first push-pull triode and the fourth push-pull triode are respectively connected to the two ends of the current detection resistor group.

5. The high-precision rotary transducer excitation output circuit according to claim 1, characterized in that, The power amplifier circuit further includes a second triode and a third triode connected in series at the emitter, the base of the second triode is connected to the emitter of the first push-pull triode, and the collector of the second triode is connected to the base of the first push-pull triode; the base of the third triode is connected to the emitter of the fourth push-pull triode, and the collector of the third triode is connected to the base of the fourth push-pull triode.

6. The high-precision rotary transducer excitation output circuit according to claim 5, characterized in that, The current detection resistor group includes a third resistor and a fourth resistor connected in parallel, which are connected in series with a tenth resistor and an eleventh resistor connected in parallel; the common end of the fourth resistor and the eleventh resistor is connected to the anti-interference filter circuit.

7. The high-precision rotary transducer excitation output circuit according to claim 6, characterized in that, The anti-interference filter circuit includes a common mode inductor and a bypass capacitor group, the input end of the common mode inductor is connected to the output end of the two groups of power amplifier circuits respectively, the bypass capacitor group includes a ninth capacitor and a tenth capacitor connected to the output end of the common mode inductor respectively, and the other ends of the ninth capacitor and the tenth capacitor are both grounded.

8. The high-precision rotary transducer excitation output circuit according to claim 1, characterized in that, The anti-interference filter circuit includes an ESD static protection tube, the ESD static protection tube is connected to the output end of the anti-interference filter circuit at the same direction of both ends, and the other same direction of both ends of the ESD static protection tube is grounded.

9. The high-precision rotary transducer excitation output circuit according to claim 1, characterized in that, ​ 10. The high-precision rotary transducer excitation output circuit according to claim 9, characterized in that, ​

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