A method for exciting a rotary transformer with adjustable amplitude and frequency

Abstract

The application discloses a rotating variable excitation method with adjustable amplitude and frequency, which is based on a rotating variable excitation circuit comprising an SPWM voltage source, an operational amplifier, a triode and a differential amplifier; different from a special rotating variable excitation chip, the SPWM signal output by a controller such as a DSP and a FPGA is filtered to obtain a sine signal, the sine signal is converted from a single-ended signal to a differential signal by the triode, the direct current is filtered out by the capacitor, and finally the signal is amplified by the differential amplifier to obtain the required rotating variable excitation signal.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of motor control, and particularly relates to a resolver excitation method with adjustable excitation signal amplitude and frequency. BACKGROUND

[0002] In many motor controllers, a position signal is obtained through a resolver. The resolver needs an excitation signal input, and then outputs a sine and cosine signal to indicate position information. Usually, the excitation and decoding of the resolver need a special resolver chip to participate, and sometimes an FPGA is needed to increase to decode, which increases the complexity and cost of the circuit.

[0003] On the other hand, the excitation signal output by the special resolver chip is usually fixed in amplitude, which leads to the need to increase an additional amplification circuit in the later stage when adapting to different types of resolver, and to manually weld and modify the circuit resistance to modify the amplification multiple, which also increases the complexity and cost of the circuit, and reduces the flexibility of the circuit. SUMMARY

[0004] The present application aims to overcome the above shortcomings, and provides a resolver excitation method with adjustable amplitude and frequency, which controls the frequency and amplitude through programming control of a control chip, and the resolver excitation method is simple.

[0005] The technical scheme adopted by the present application to solve its technical problems is: a rotating transformer excitation method with adjustable amplitude and frequency, based on a rotating transformer excitation circuit comprising an SPWM voltage source, an operational amplifier, a transistor and a differential amplifier; the SPWM signal output by the SPWM voltage source is converted into a sinusoidal signal after a filtering circuit, and is input to the reverse input end of the operational amplifier; the fixed voltage source V1 is divided into V1 / 2 by two 10kΩ voltage dividing resistors, and is connected to the same input end of the operational amplifier, as the voltage uplift of the output of the operational amplifier 2; this stage converts the SPWM signal into a sinusoidal wave voltage signal with bias and amplitude equal to V1 / 2; the operational amplifier output sinusoidal signal with bias is connected to the base of the transistor; the emitter of the transistor is connected to the ground through a 10kΩ grounding resistor; the collector of the transistor is connected to the fixed voltage source V2 in sequence through a 20Ω resistor and a 10kΩ resistor; the transistor and the 20Ω resistor form a sinusoidal voltage source; the sinusoidal wave voltage signal at the base is converted into a sinusoidal wave current signal at the collector, and then flows through the 20Ω resistor to become a voltage signal; the transistor works in the amplification zone, controls the collector current of the transistor; the connection point of the 20Ω resistor and the 10kΩ resistor is connected to one input end of the differential amplifier through the blocking capacitor C3; the connection point of the emitter of the transistor and the 10kΩ grounding resistor is connected to the other input end of the differential amplifier through the blocking capacitor C4; the current signal is converted into a sinusoidal wave voltage signal on the 20Ω resistor, and then the direct current signal is filtered through the blocking capacitors C3 and C4, so that only the differential sinusoidal signal containing alternating current signal is obtained; finally, the amplitude of the differential sinusoidal signal is amplified by the differential amplifier, and the driving capability is improved; the differential amplifier amplifies the input differential sinusoidal signal, and finally outputs the excitation signal; and finally, the excitation signal suitable for the rotating transformer is obtained.

[0006] Further, the filtering circuit is composed of fixed resistors R1-R3 and fixed capacitors C1-C2; one end of the resistor R1 is connected to the positive electrode of the SPWM voltage source; the other end of the resistor R1 is connected to the capacitor C1 and the resistors R2 and R3 at the same time; the other end of the capacitor C1 is connected to the negative electrode of the SPWM voltage source and the ground at the same time; the other end of the resistor R3 is connected to one end of the capacitor C2, the output end of the operational amplifier and the base of the transistor at the same time; the other end of the resistor R2 is connected to the other end of the capacitor C2 and the reverse input end of the operational amplifier at the same time.

[0007] Further, the values of the blocking capacitors C3 and C4 are equal.

[0008] The present application has the following advantages: by controlling the frequency of the SPWM signal, the frequency of the excitation signal is controlled, and by controlling the number of square waves in a sinusoidal wave cycle, the amplitude of the excitation signal is controlled. The rotating transformer excitation circuit of the rotating transformer excitation method of the present application has simple control logic, few devices, and can program and adjust the frequency and amplitude of the excitation signal, and has certain advantages. BRIEF DESCRIPTION OF DRAWINGS

[0009] Figure 1 The circuit principle diagram of the excitation circuit of the application;

[0010] Figure 2 The simulation circuit diagram of the excitation circuit of the application;

[0011] Figure 3 For Figure 2 The corresponding simulation result diagram. DETAILED DESCRIPTION

[0012] For the purpose and technical solution of the application, the following will be described in detail in combination with the drawings and specific embodiments.

[0013] The application discloses a rotating variable excitation method with adjustable amplitude and frequency, which is based on a rotating variable excitation circuit including an SPWM voltage source 1, a filter circuit, an operational amplifier 2, a triode 3 and a differential amplifier 4.

[0014] The input of the rotating variable excitation circuit is the output of a control chip, which is equivalent to an SPWM voltage source 1, V1 and V2 are fixed voltage sources, filter resistors R1, R2 and R3 are fixed resistors, filter capacitors C1, C2, a blocking capacitor C3 and a blocking capacitor C4 are fixed capacitors, and other devices are shown in Figure 1 .

[0015] The filter circuit is composed of fixed resistors R1-R3 and fixed capacitors C1-C2, one end of the resistor R1 is connected to the positive electrode of the SPWM voltage source 1, the other end of the resistor R1 is connected to the capacitor C1 and resistors R2 and R3 at the same time, the other end of the capacitor C1 is connected to the negative electrode of the SPWM voltage source 1 and the ground at the same time, the other end of the resistor R3 is connected to one end of the capacitor C2, the output end of the operational amplifier 2 and the base of the triode 3 at the same time, and the other end of the resistor R2 is connected to the other end of the capacitor C2 and the reverse input end of the operational amplifier 2 at the same time.

[0016] The application uses a control chip such as DSP or FPGA to output an SPWM signal, and the frequency of the SPWM signal and the number of pulses in a period can be controlled through programming. Because the frequency of the SPWM signal modulation wave corresponds to the frequency of the excitation signal, and the number of high-level pulses in a period of the SPWM signal affects the amplitude of the excitation signal, according to this rule, the controller can control the frequency and amplitude of the final excitation signal by adjusting the SPWM signal.

[0017] The rotating variable excitation method has the following steps:

[0018] Firstly, the SPWM voltage source 1 outputs the SPWM signal, which is converted into a sine signal after the filtering circuit, and is input into the reverse input end of the operational amplifier 2; the fixed voltage source V1 is divided into V1 / 2 by two 10kΩ voltage dividing resistors, and is connected to the same input end of the operational amplifier 2 as the voltage lifting of the output of the operational amplifier 2; this stage converts the SPWM signal into a sine wave voltage signal with bias and amplitude equal to V1 / 2.

[0019] Then, the sine signal with bias is connected to the base of the triode 3, the emitter of the triode 3 is connected to the ground through a 10kΩ grounding resistor, the collector of the triode 3 is connected to the fixed voltage source V2 through a 20Ω resistor and a 10kΩ resistor in series; the triode 3 is divided by two 10kΩ resistors and a 20Ω resistor, and works in the amplification area; the sine wave voltage signal at the base is converted into a sine wave current signal at the collector, the current flows through the 20Ω resistor to become a voltage, and finally the triode 3 and the 20Ω resistor form a sine voltage source.

[0020] Finally, the sine wave current signal at the base is converted into a voltage signal after flowing through the 20Ω resistor, the triode 3 works in the amplification area, controls the collector current of the triode 3, the connection point of the 20Ω resistor and the 10kΩ resistor is connected to one input end of the differential amplifier 4 through the blocking capacitor C3, the connection point of the emitter of the triode 3 and the 10kΩ grounding resistor is connected to the other input end of the differential amplifier 4 through the blocking capacitor C4, the current signal is converted into a sine wave voltage signal on the 20Ω resistor, and then the direct current signal is filtered out through the blocking of the blocking capacitor C3 and the blocking capacitor C4, so that the differential sine signal containing only alternating current signal is obtained, and finally the amplitude of the differential sine signal is amplified by the differential amplifier 4 and the driving ability is improved, the differential amplifier 4 amplifies the input differential sine signal, and finally outputs the excitation signal, and the excitation signal suitable for the rotary transformer is obtained.

[0021] Because of symmetry, the values of the blocking capacitor C3 and the blocking capacitor C4 are equal. The sine voltage is filtered through C3 and C4, and finally the amplitude of the differential amplifier is amplified and the driving ability is improved to obtain the final excitation signal.

[0022] The frequency of the SPWM signal modulation wave corresponds to the frequency of the excitation signal, and the number of high level pulses of a period of the SPWM signal affects the amplitude of the excitation signal; according to this rule, the controller can control the frequency and amplitude of the final excitation signal by adjusting the SPWM signal.

[0023] Figure 2 The simulation circuit diagram of the application is shown in Figure 1, Figure 3 The simulation circuit diagram of the application is shown in Figure 1, Figure 2 The simulation circuit diagram of the application is shown in Figure 1,

[0024] The square wave in the SPWM signal is a carrier wave, and the change period of the SPWM signal corresponds to the period of the excitation signal; the number of square waves in one period of the SPWM signal affects the amplitude of the excitation signal, so the frequency and amplitude of the excitation signal can be adjusted by adjusting the SPWM.

[0025] The present application is not limited to the above-mentioned best mode, and any person skilled in the art can derive other modified and improved products under the inspiration of the present application, but regardless of any change in shape or structure, any technical solution with the same or similar technical solution as the present application falls within the protection scope of the present application.

Claims

1. A rotator excitation method with adjustable amplitude and frequency, characterized in that: Based on a rotary excitation circuit including an SPWM voltage source (1), an operational amplifier (2), a transistor (3), and a differential amplifier (4); the SPWM voltage source (1) outputs an SPWM signal, which is then filtered and converted into a sinusoidal signal and input to the inverting input of the operational amplifier (2). The fixed voltage source V1 is divided into V1 / 2 by two 10kΩ voltage divider resistors and then connected to the non-inverting input of the operational amplifier (2). The operational amplifier (2) converts the SPWM signal into a biased sinusoidal voltage signal with an amplitude equal to V1 / 2. The operational amplifier (2) outputs a biased sinusoidal signal and connects it to the base of the transistor (3). The emitter of the transistor (3) is grounded through a 10kΩ grounding resistor. The collector of the transistor (3) is sequentially... After connecting a 20Ω resistor and a 10kΩ resistor in series, the signal is connected to a fixed voltage source V2. The sinusoidal voltage signal at the base is converted into a sinusoidal current signal at the collector and then flows through the 20Ω resistor to become a voltage signal. The connection point of the 20Ω resistor and the 10kΩ resistor is connected to one input terminal of the differential amplifier (4) through the DC blocking capacitor C3. The connection point of the emitter of the transistor (3) and the 10kΩ grounding resistor is connected to the other input terminal of the differential amplifier (4) through the DC blocking capacitor C4. The current signal is converted into a sinusoidal voltage signal on the 20Ω resistor and then passes through the DC blocking capacitors C3 and C4 to obtain a differential sinusoidal signal containing only AC signal. Finally, the amplitude is amplified by the differential amplifier (4) to obtain the excitation signal of the adaptive resolver.

2. The rotator excitation method with adjustable amplitude and frequency according to claim 1, characterized in that, The filter circuit consists of fixed resistors R1 to R3 and fixed capacitors C1 to C2. One end of resistor R1 is connected to the positive terminal of the SPWM voltage source (1), and the other end of resistor R1 is connected to capacitor C1, as well as resistors R2 and R3. The other end of capacitor C1 is grounded at the same time as the negative terminal of the SPWM voltage source (1). The other end of resistor R3 is connected to one end of capacitor C2, the output terminal of operational amplifier (2), and the base of transistor (3). The other end of resistor R2 is connected to the other end of capacitor C2 and the inverting input terminal of operational amplifier (2).

3. A rotator excitation method with adjustable amplitude and frequency according to claim 1 or 2, characterized in that, The DC blocking capacitors C3 and C4 have the same value.

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