A resolver excitation and acquisition circuit

Abstract

The utility model relates to a kind of rotary transformer excitation and collection circuit, including excitation circuit, rotary transformer and collection circuit, the output end of excitation circuit is connected to rotary transformer, the output end of rotary transformer is connected to collection circuit;The excitation circuit includes three-stage amplification circuit: first-stage same-phase proportional amplification circuit, second-stage same-phase proportional amplification circuit with reference bias, third-stage amplification drive circuit;The collection circuit includes: filter capacitor and differential amplification circuit.This scheme does not need to adopt special excitation chip and decoding chip, and can greatly reduce hardware cost.

Description

Technical Field

[0001] This utility model relates to the field of rotary transformer technology, and in particular to a rotary transformer excitation and acquisition circuit. Background Technology

[0002] The excitation and acquisition circuits of conventional resolvers typically employ dedicated excitation and acquisition / decoding chips for signal processing, resulting in poor circuit versatility and high cost. While some research has attempted to replace dedicated chips with discrete components, these designs still suffer from the following drawbacks: insufficient excitation signal driving capability, making it difficult to match the high impedance characteristics of the resolver; and reliance on complex peripheral circuits, failing to significantly reduce system cost. Summary of the Invention

[0003] In order to solve the above problems, the purpose of this utility model is to provide a rotary transformer excitation and acquisition circuit.

[0004] A rotary transformer excitation and acquisition circuit includes an excitation circuit, a rotary transformer, and an acquisition circuit. The output terminal of the excitation circuit is connected to the rotary transformer, and the output terminal of the rotary transformer is connected to the acquisition circuit.

[0005] The excitation circuit includes a three-stage amplifier circuit:

[0006] The first-stage non-inverting amplifier circuit includes an operational amplifier U1, one input terminal of which is connected to a PWM signal for amplifying the input PWM signal.

[0007] The second-stage non-inverting amplifier circuit with reference bias includes operational amplifier U2. One input terminal of operational amplifier U2 is connected to the output terminal of operational amplifier U1, and the other input terminal of operational amplifier U2 is connected to the reference voltage Vref1, which is used to superimpose the bias voltage on the first-stage amplified signal.

[0008] The third-stage amplification drive circuit includes an operational amplifier U3. One input terminal of the operational amplifier U3 is connected to the output terminal of the operational amplifier U2, which is used to further amplify the signal and output it to the EXC+ and EXC- terminals of the rotary transformer through a push-pull structure.

[0009] The acquisition circuit includes:

[0010] A filter capacitor is connected in parallel between the Sin+ and Sin- signals or Cos+ and Cos- signals of the rotary transformer to filter out high-frequency noise.

[0011] The differential amplifier circuit includes an operational amplifier U4, with the output terminal of the filter capacitor connected to the input terminal of the operational amplifier U4, and one of the input terminals of the operational amplifier U4 connected to a reference voltage Vref2, used to convert the filtered Sin+ and Sin- signals or Cos+ and Cos- signals into biased analog output signals.

[0012] Preferably, the third-stage amplifier driving circuit includes diode D1, diode D2, transistor Q1, and transistor Q2;

[0013] Diode D1 is connected between the output of operational amplifier U3 and the base of transistor Q1 to control the conduction state of Q1;

[0014] Diode D2 is connected between resistor R10 and the base of transistor Q2 to control the conduction state of Q2;

[0015] The collector of transistor Q1 is connected to capacitor C1 through resistor R11, and the emitter of transistor Q2 is grounded. The two form a push-pull structure to enhance the driving capability.

[0016] Preferably, in the differential amplifier circuit, resistor R15 is connected between the input and output terminals of operational amplifier U4 to adjust the amplification gain.

[0017] Preferably, in the second stage amplifier circuit of the excitation circuit, the reference voltage Vref1 is connected to the inverting input terminal of the operational amplifier U2 through resistor R5 to provide a fixed bias for the signal.

[0018] This application, by adopting the above-mentioned solution, has the following technical effects:

[0019] The circuit is constructed using general-purpose components such as resistors, capacitors, and operational amplifiers, eliminating the need for dedicated excitation and decoding chips and significantly reducing hardware costs. The excitation circuit employs a three-stage amplification structure, progressively amplifying and superimposing bias voltages to boost the PWM signal from the microcontroller's low drive capability to a high drive range suitable for the resolver. Furthermore, a push-pull structure composed of transistors Q1 and Q2 enhances the output current, ensuring stable output of the excitation signal under complex loads. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the circuit structure of this application;

[0021] Figure 2 This is a schematic diagram of the circuit structure of the excitation circuit;

[0022] Figure 3 This is a schematic diagram of the data acquisition circuit. Detailed Implementation

[0023] The embodiments of this utility model are described in detail below.

[0024] like Figure 1 As shown, this embodiment provides a rotary transformer excitation and acquisition circuit, including an excitation circuit, a rotary transformer, and an acquisition circuit. The output terminal of the excitation circuit is connected to the rotary transformer, and the output terminal of the rotary transformer is connected to the acquisition circuit.

[0025] like Figure 2 As shown, the excitation circuit includes a three-stage amplifier circuit: a first-stage non-inverting proportional amplifier circuit, a second-stage non-inverting proportional amplifier circuit with reference bias, and a third-stage amplification and drive circuit. By progressively amplifying and superimposing the bias voltage, the PWM signal is boosted from the low drive capability signal output by the microcontroller to a high drive range suitable for the rotary transformer. At the same time, the push-pull structure composed of transistors Q1 and Q2 enhances the output current, solving the problem of insufficient drive capability in existing discrete component solutions and ensuring stable output of the excitation signal (EXC+, EXC-) under complex loads.

[0026] The first-stage non-inverting amplifier circuit includes an operational amplifier U1, one input of which is connected to a PWM signal for amplifying the input PWM signal. The circuit also includes resistors R1, R2, and R3. R2 serves as an input resistor, connected between the PWM signal source and the non-inverting input of operational amplifier U1, used to adjust the amplitude of the input signal and limit the input current. One end of resistor R1 is grounded, and the other end is connected to the inverting input of operational amplifier U1. One end of resistor R3 is connected to the output of operational amplifier U1, and the other end is connected to its inverting input, forming a feedback network with resistor R1 to set the gain of the first-stage amplifier circuit.

[0027] The second-stage non-inverting amplifier circuit with reference bias includes operational amplifier U2. One input of operational amplifier U2 is connected to the output of operational amplifier U1, and the other input is connected to a reference voltage Vref1, used to superimpose a bias voltage onto the first-stage amplified signal. The second-stage non-inverting amplifier circuit with reference bias also includes resistors R4, R5, and R6. Resistor R4 is connected between the output of operational amplifier U1 and the non-inverting input of operational amplifier U2; resistor R5 is connected between the reference voltage Vref1 and the inverting input of operational amplifier U2; and resistor R6 is connected between the output of operational amplifier U2 and its inverting input. Together with resistors R4 and R5, these resistors adjust the bias voltage and gain of the second-stage amplifier circuit.

[0028] The third-stage amplification and driving circuit includes operational amplifier U3. One input terminal of operational amplifier U3 is connected to the output terminal of operational amplifier U2, used to further amplify the signal and output it to the EXC+ and EXC- terminals of the resolver through a push-pull structure. The third-stage amplification and driving circuit includes diodes D1 and D2, transistors Q1 and Q2; diode D1 is connected between the output terminal of operational amplifier U3 and the base of transistor Q1 to control the conduction state of Q1; diode D2 is connected between resistor R10 and the base of transistor Q2 to control the conduction state of Q2; the collector of transistor Q1 is connected to capacitor C1 through resistor R11, and the emitter of transistor Q2 is grounded, forming a push-pull structure to enhance the driving capability. Figure 2 As shown, the third-stage amplifier driver circuit also includes resistors R7-R12. Resistor R7 is connected between the output of operational amplifier U2 and the non-inverting input of operational amplifier U3, serving as a signal transmission resistor to transmit the signal amplified by the second stage to the third-stage operational amplifier U3, while limiting the input current to prevent overload of the U3 input. Resistor R8 is connected between the inverting input of operational amplifier U3 and ground, forming a feedback network with resistor R7 to set the gain of the third-stage amplifier circuit. Resistor R9 is connected between diode D1 and the base of transistor Q1, serving as a base current limiting resistor to limit the current flowing into the base of Q1, preventing damage to the transistor due to overcurrent, and adjusting the conduction speed of Q1 to ensure the symmetry of the push-pull output. Resistor R10 is connected between diode D2 and the base of transistor Q2, serving as a base current limiting resistor for Q2, balancing the drive signals of Q1 and Q2 in the push-pull circuit, and avoiding output distortion caused by inconsistent conduction states of the two transistors. Resistor R11 is placed between the collector of transistor Q1 and capacitor C1 as the collector load resistor; resistor R12 is designed symmetrically with R11 and serves as the collector load resistor of Q2.

[0029] like Figure 3As shown, the acquisition circuit includes a filter capacitor and a differential amplifier circuit. C2, acting as a filter capacitor, is connected in parallel between the Sin+ and Sin- signals or Cos+ and Cos- signals of the resolver to filter out high-frequency noise. The differential amplifier circuit includes an operational amplifier U4. The output of the filter capacitor is connected to the input of operational amplifier U4, and one of the inputs of operational amplifier U4 is connected to a reference voltage Vref2. This is used to convert the filtered Sin+ and Sin- signals or Cos+ and Cos- signals into biased analog output signals. In the differential amplifier circuit, resistor R15 is connected between the input and output of operational amplifier U4 to adjust the amplification gain. The analog signal output from the differential amplifier circuit of the acquisition circuit can be directly input to the microcontroller unit for resolver angle decoding. The acquisition circuit uses differential amplification technology (resistors R13-R16 and operational amplifier U4) combined with the high-frequency noise filtering function of capacitor C2 to effectively suppress common-mode noise in the output signal (Sin+, Sin-, Cos+, Cos-) of the rotary transformer, improving the signal-to-noise ratio by more than 30%, and the linearity error of the output analog signal is less than 0.5%, significantly improving the angle decoding accuracy.

[0030] The basic working principle of this utility model is as follows:

[0031] The PWM control signal of the excitation circuit is input to the input terminal of operational amplifier U1 through resistor R2. After being amplified by resistors R3, R1, and operational amplifier U1, it is input to the positive bias amplified signal generated by resistors R4, R6, R5, voltage reference Vref1, and operational amplifier U2. This signal is input to the input terminal of operational amplifier U3 through resistor R7. The output signal of amplifier U3 is controlled by resistor R9 and diode D1 to output the transistor Q1. The output signal is then sent to capacitor C1 through resistor R11. Capacitor C1 outputs the EXC+ positive excitation signal to the resolver. Resistor R10 and diode D2 control transistor Q2. The emitter of transistor Q2 outputs the EXC- positive excitation signal to the resolver.

[0032] The Sin+ and Sin- signals output from the resolver are filtered by capacitor C2, and then generated into biased analog signals via resistors R13, R15, R14, R16, and voltage reference Vref2. The acquisition circuit and principle for the Cos+ and Cos- signals are the same as for the Sin signal. At this point, the resolver output signal acquisition is complete.

[0033] The above solution utilizes only common components such as resistors, capacitors, and operational amplifiers to construct the circuit, effectively reducing hardware costs. Furthermore, circuit parameters (such as amplification factor and bias voltage) can be flexibly adapted to different types of rotary transformers by adjusting resistor values, significantly improving versatility. The excitation and acquisition circuits can be modularly designed to reduce the number of external components.

[0034] Although embodiments of the present invention have been shown and described, those skilled in the art will understand that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the present invention, the scope of which is defined by the claims and their equivalents.

Claims

1. A rotary transformer excitation and acquisition circuit, characterized in that, It includes an excitation circuit, a rotary transformer, and a data acquisition circuit. The output of the excitation circuit is connected to the rotary transformer, and the output of the rotary transformer is connected to the data acquisition circuit. The excitation circuit includes a three-stage amplifier circuit: The first-stage non-inverting amplifier circuit includes an operational amplifier U1, one input terminal of which is connected to a PWM signal for amplifying the input PWM signal. The second-stage non-inverting amplifier circuit with reference bias includes operational amplifier U2. One input terminal of operational amplifier U2 is connected to the output terminal of operational amplifier U1, and the other input terminal of operational amplifier U2 is connected to the reference voltage Vref1, which is used to superimpose the bias voltage on the first-stage amplified signal. The third-stage amplification drive circuit includes an operational amplifier U3. One input terminal of the operational amplifier U3 is connected to the output terminal of the operational amplifier U2, which is used to further amplify the signal and output it to the EXC+ and EXC- terminals of the rotary transformer through a push-pull structure. The acquisition circuit includes: A filter capacitor is connected in parallel between the Sin+ and Sin- signals or Cos+ and Cos- signals of the rotary transformer to filter out high-frequency noise. The differential amplifier circuit includes an operational amplifier U4, with the output terminal of the filter capacitor connected to the input terminal of the operational amplifier U4, and one of the input terminals of the operational amplifier U4 connected to a reference voltage Vref2, used to convert the filtered Sin+ and Sin- signals or Cos+ and Cos- signals into biased analog output signals.

2. The rotary transformer excitation and acquisition circuit according to claim 1, characterized in that, The third-stage amplifier driving circuit includes diode D1, diode D2, transistor Q1, and transistor Q2; Diode D1 is connected between the output of operational amplifier U3 and the base of transistor Q1 to control the conduction state of Q1; Diode D2 is connected between resistor R10 and the base of transistor Q2 to control the conduction state of Q2; The collector of transistor Q1 is connected to capacitor C1 through resistor R11, and the emitter of transistor Q2 is grounded. The two form a push-pull structure to enhance the driving capability.

3. The rotary transformer excitation and acquisition circuit according to claim 1, characterized in that, In the differential amplifier circuit, resistor R15 is connected between the input and output terminals of operational amplifier U4 to adjust the amplification gain.

4. The rotary transformer excitation and acquisition circuit according to claim 1, characterized in that, In the second stage amplifier circuit of the excitation circuit, the reference voltage Vref1 is connected to the inverting input terminal of the operational amplifier U2 through resistor R5 to provide a fixed bias for the signal.

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