Time-sharing orthogonal high voltage excitation circuit structure

Abstract

The invention discloses a time-sharing orthogonal high-voltage excitation circuit structure, including a low-voltage sinusoidal signal generating circuit for generating four-way orthogonal low-voltage sinusoidal signals; and a signal amplifying circuit for amplifying the four-way orthogonal low-voltage sinusoidal signals. The four-way orthogonal low-voltage sinusoidal signals output by the low-voltage sinusoidal signal generating circuit are respectively connected to the channel 1 of the double-throw end of the first group of four-way single-pole double-throw analog switches, and the channel 2 of the double-throw end of the first group of four-way single-pole double-throw analog switches is all grounded; the four-way orthogonal low-voltage sinusoidal signals output by the low-voltage sinusoidal signal generating circuit are simultaneously connected to the channel 2 of the double-throw end of the second group of four-way single-pole double-throw analog switches, and the channel 1 of the double-throw end of the second group of four-way single-pole double-throw analog switches is all grounded; the single-pole ends of all single-pole double-throw analog switches are respectively connected to high-voltage operational amplifiers as output ends to amplify the output signals. The circuit structure has low cost, a certain output signal state, is not easily interfered, and has a more accurate phase difference.

Description

Technical Field

[0001] The invention relates to an improvement of a sensor excitation circuit, and in particular to a time-sharing orthogonal high-voltage excitation circuit structure, belonging to the technical field of circuit structures. Background Art

[0002] At present, with the improvement of industrial automation, the application market of time-grating displacement sensors is getting bigger and bigger. The signal processing flow of the internal circuit of the time-grating displacement sensor is as follows: two groups of four-way high-voltage excitation signals (four-way signals in each group, a total of eight-way signals) are generated and connected to the sensor stator, the sensor mover receives the induction signal, and then processes the received induction signal, and finally outputs the displacement signal.

[0003] The four-channel high-voltage excitation signal has the following requirements: 1. They are four sinusoidal signals with the same frequency; 2. The four signals are 90° (1 / 4 cycle) apart in phase; 3. The peak-to-peak values ​​of the four sinusoidal waves are equal, and the peak-to-peak value range is 10~36V.

[0004] In order to obtain four high-voltage excitation signals, two steps are generally required in circuit design:

[0005] Step 1: Generate four orthogonal low-voltage sinusoidal signals;

[0006] Step 2: Amplify the signal generated in step 1.

[0007] As for how to generate two groups of four-way high-voltage excitation signals in parallel, the four-way method can be copied into one group, or an analog switch can be used in step 2 to generate two groups of four-way signals in parallel.

[0008] In the prior art, there are usually two implementation schemes for generating four orthogonal low-voltage sinusoidal signals (i.e., step 1):

[0009] Solution 1: Use DDS (direct digital synthesizer) solution, such as Figure 1 Specifically, the 4-channel DDS chips are set to output the same-frequency sine wave mode through the CPU bus, and then the DDS start signals with a phase difference of 90° are output through the 4 IO ports of the CPU, so that DDS1-DDS4 can output orthogonal same-frequency low-voltage sine signals PA1-PA4 in turn.

[0010] The disadvantage of this solution is that the phase of the signal generated by the four-channel DDS chip can be precisely controlled, but the amplitude cannot be kept consistent. The consistency of the four-channel amplitude depends on the consistency of the four-channel DDS chip itself.

[0011] Solution 2: Use a 4-channel DAC (digital-to-analog converter) solution, such as Figure 2Specifically, the 4-way DA chip is configured through the CPU bus to perform DA conversion according to the sine wave, and then the DA chip is controlled to load data or start through the 4 IO ports of the CPU, so that DA1-DA4 sequentially outputs orthogonal low-voltage sine signals PA1-PA4 of the same frequency.

[0012] The disadvantages of this solution are: a large number of DA chips are used, and high-performance DA chips are more expensive.

[0013] In the prior art, there are usually two implementation schemes for amplifying four orthogonal low-voltage sinusoidal signals (i.e., step 2):

[0014] Solution 1: Copy the four-way orthogonal low-voltage sinusoidal signals PA1-PA4 generated in step 1 to obtain another four-way orthogonal low-voltage sinusoidal signals QA1-QA4, and then amplify the signals through eight-way high-voltage operational amplifiers OP1-OP8 to obtain two groups of four-way orthogonal high-voltage sinusoidal signals PB1-PB4 and QB1-QB4, as shown in FIG. Figure 3 shown.

[0015] The disadvantages of this solution are: the solution of step one needs to be copied, and the cost of the device in step one is relatively high.

[0016] Solution 2: The four orthogonal low-voltage sinusoidal signals PA1-PA4 generated in step 1 are switched to channel 1 and channel 2 of the analog switch through four single-pole double-throw analog switches in a time-sharing manner. When the four analog switches are switched to channel 1, the signals PA1-PA4 are respectively amplified by four high-voltage operational amplifiers OP1, OP3, OP5 and OP7 to obtain the first group of four orthogonal high-voltage sinusoidal signals PB1-PB4; when the four analog switches are switched to channel 2, the signals PA1-PA4 are respectively amplified by four high-voltage operational amplifiers OP2, OP4, OP6 and OP8 to obtain the second group of four orthogonal high-voltage sinusoidal signals QB1-QB4, as shown in FIG. Figure 4 shown.

[0017] The disadvantage of this solution is that when all four analog switches are switched to channel 1, channel 2 is suspended and easily interfered with, resulting in the second group of signals QB1-QB4 being in an uncertain state. Similarly, when all four analog switches are switched to channel 2, channel 1 is suspended and easily interfered with, resulting in the first group of signals PB1-PB4 being in an uncertain state. Summary of the invention

[0018] In view of the above-mentioned deficiencies in the prior art, the purpose of the present invention is to provide a time-sharing orthogonal high-voltage excitation circuit structure, which has low cost, a certain output signal state, is not easily disturbed, and has a more accurate phase difference.

[0019] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0020] Time-sharing orthogonal high-voltage excitation circuit structure, including

[0021] A low-voltage sinusoidal signal generating circuit, used for generating four orthogonal low-voltage sinusoidal signals PA1-PA4;

[0022] The signal amplification circuit is used to amplify four orthogonal low-voltage sinusoidal signals to obtain the required high voltage;

[0023] The signal amplification circuit comprises two groups of four-way single-pole double-throw analog switches and eight-way high-voltage operational amplifiers; the four-way orthogonal low-voltage sinusoidal signals PA1-PA4 output by the low-voltage sinusoidal signal generating circuit are respectively connected to channel 1 of the double-throw end of the first group of four-way single-pole double-throw analog switches, and the channel 2 of the double-throw end of the first group of four-way single-pole double-throw analog switches is all grounded; the four-way orthogonal low-voltage sinusoidal signals PA1-PA4 output by the low-voltage sinusoidal signal generating circuit are simultaneously branched to channel 2 of the double-throw end of the second group of four-way single-pole double-throw analog switches, and the channel 1 of the double-throw end of the second group of four-way single-pole double-throw analog switches is all grounded; the single-pole ends of all single-pole double-throw analog switches are respectively connected to high-voltage operational amplifiers as output ends to amplify the output signals.

[0024] Among them, the single-pole double-throw analog switch power supply voltage VDD is less than 5V.

[0025] The signal amplification circuit can also be implemented according to the following structure: the signal amplification circuit includes two groups of four-way single-pole double-throw analog switches and four-way high-voltage operational amplifiers; the four outputs of the low-voltage sinusoidal signal generating circuit are respectively connected to the high-voltage operational amplifiers OP1-OP4 to amplify the four-way orthogonal low-voltage sinusoidal signals PA1-PA4 to obtain four-way orthogonal high-voltage sinusoidal signals PB1-PB4; the four-way high-voltage sinusoidal signals PB1-PB4 are respectively connected to channel 1 of the double-throw end of the first group of four-way single-pole double-throw analog switches, and the channel 2 of the double-throw end of the first group of four-way single-pole double-throw analog switches is all grounded; the four-way high-voltage sinusoidal signals PB1-PB4 are simultaneously connected to channel 2 of the double-throw end of the second group of four-way single-pole double-throw analog switches, and the channel 1 of the double-throw end of the second group of four-way single-pole double-throw analog switches is all grounded; the single-pole ends of all single-pole double-throw analog switches serve as signal output ends.

[0026] Among them, the single-pole double-throw analog switch power supply voltage VDD is 10~36v.

[0027] The low-voltage sinusoidal signal generating circuit has a structure as follows: it includes a CPU, two digital-to-analog converters and two inverting operational amplifiers, the bus of the CPU is simultaneously connected to the two digital-to-analog converters so that the two digital-to-analog converters perform DA conversion according to a sinusoidal wave, and the two IO ports of the CPU are respectively connected to the two digital-to-analog converters to control the two digital-to-analog converters to load data or start, so that the sinusoidal signals output by the two digital-to-analog converters are orthogonal; the sinusoidal signal PA1 output by one digital-to-analog converter is connected to the inverting operational amplifier 1, and a sinusoidal signal PA2 having the same frequency and amplitude as the sinusoidal signal PA1 but opposite phase is obtained at the output end of the inverting operational amplifier 1; the sinusoidal signal PA3 output by another digital-to-analog converter is connected to the inverting operational amplifier 2, and a sinusoidal signal PA4 having the same frequency and amplitude as the sinusoidal signal PA3 but opposite phase is obtained at the output end of the inverting operational amplifier 2; the sinusoidal signals PA1, PA2, PA3 and PA4 constitute the four orthogonal low-voltage sinusoidal signals.

[0028] Another structure of the low-voltage sinusoidal signal generating circuit is: it includes a CPU and two differential digital-to-analog converters, the bus of the CPU is simultaneously connected to the two differential digital-to-analog converters so that the two differential digital-to-analog converters perform DA conversion according to a sine wave, and the two IO ports of the CPU are respectively connected to the two differential digital-to-analog converters to control the two differential digital-to-analog converters to load data or start, so that the sinusoidal signals output by the two differential digital-to-analog converters are orthogonal; one of the differential digital-to-analog converters outputs two sinusoidal signals PA1 and PA2 with opposite phases; the other differential digital-to-analog converter outputs two sinusoidal signals PA3 and PA4 with opposite phases; the sinusoidal signals PA1, PA2, PA3 and PA4 constitute the four orthogonal low-voltage sinusoidal signals.

[0029] Compared with the prior art, the present invention has the following advantages:

[0030] 1. The signal amplification circuit of the present invention does not need to copy the four-way orthogonal low-voltage sinusoidal signal, but only needs to switch through the analog switch. Any channel of the analog switch will not be suspended, the signal state is determined, and it is not easy to be interfered. Moreover, when the analog switch uses a low-voltage analog switch, there are more optional models, greater selection flexibility, and lower cost.

[0031] 2. The low-voltage sinusoidal signal generating circuit of the present invention reduces the circuit cost because it only uses two DAs. Furthermore, when a differential output chip is used, the two signals outputted are strictly in anti-phase, and the phase difference is more accurate. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1A schematic diagram of the structure of a scheme 1 for generating four-way orthogonal low-voltage sinusoidal signals in the prior art;

[0033] Figure 2 A schematic diagram of the structure of a scheme 2 for generating four-way orthogonal low-voltage sinusoidal signals in the prior art;

[0034] Figure 3 It is a structural schematic diagram of a four-way orthogonal low-voltage sinusoidal signal amplification scheme 1 in the prior art;

[0035] Figure 4 It is a structural schematic diagram of a four-way orthogonal low-voltage sinusoidal signal amplification scheme 2 in the prior art;

[0036] Figure 5 A schematic diagram of the structure of a scheme 1 for generating four-way orthogonal low-voltage sinusoidal signals according to the present invention;

[0037] Figure 6 The schematic diagram of the structure of the scheme 2 for generating four-way orthogonal low-voltage sinusoidal signals of the present invention;

[0038] Figure 7 This is a schematic diagram of the structure of a four-way orthogonal low-voltage sinusoidal signal amplification scheme 1 of the present invention;

[0039] Figure 8 This is a structural schematic diagram of a four-way orthogonal low-voltage sinusoidal signal amplification scheme 2 of the present invention. DETAILED DESCRIPTION

[0040] In order to make the purpose, technical scheme and advantages of the embodiments of the present invention clearer, the technical scheme in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. The components of the embodiments of the present invention generally described and shown in the drawings here can be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present invention provided in the drawings is not intended to limit the scope of the claimed invention, but merely represents selected embodiments of the present invention. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work belong to the scope of protection of the present invention.

[0041] For ease of understanding, some of the professional terms involved in this application are explained as follows. Orthogonal: Two signals of equal amplitude and frequency with a phase difference of 90° (1 / 4 cycle) are called orthogonal. Differential: Two signals of equal amplitude and frequency with a phase difference of 180° (1 / 2 cycle) are called differential. Time-sharing: For example, for a switch, the two states of "on" and "off" cannot appear at the same time, so you can only turn it to "on" first and then to "off", and there is a time sequence relationship.

[0042] The time-sharing orthogonal high-voltage excitation circuit structure of the present invention includes two parts. The first part is a low-voltage sinusoidal signal generating circuit, which is used to generate four orthogonal low-voltage sinusoidal signals PA1-PA4; the second part is a signal amplifying circuit, which is used to amplify the four orthogonal low-voltage sinusoidal signals to obtain the required high voltage. The two parts are described in detail below.

[0043] The first part of the low voltage sinusoidal signal generation circuit has two specific implementation schemes:

[0044] Solution 1: Use two DACs (digital-to-analog converters) in combination with an inverter, such as Figure 5 As shown. Specifically: configure two DA chips through the CPU bus to perform DA conversion according to the sine wave, and then control the DA chip to load data or start through the two IO ports of the CPU, so that the sine signal PA1 output by DA1 is orthogonal to the sine signal PA3 output by DA2 (the phase difference is 90°). After PA1 passes through the inverting operational amplifier 1, the output signal PA2 has the same frequency and amplitude as PA1, but the phase is opposite (the phase difference is 180°). Similarly, the output PA4 after the inversion of signal PA3 is also opposite to the phase of PA3.

[0045] Solution 1 uses a dual-channel DA converter to realize 4 orthogonal sinusoidal signals; each channel of the DA outputs a pair of differential signals, and the differential signals output by the two channels are orthogonal to each other.

[0046] The advantages of this solution are: only two DA channels are used, which reduces the cost.

[0047] The disadvantage of this solution is that the signal will be delayed when passing through the inverting operational amplifier, so the phase difference between PA1 and PA2 and the phase difference between PA3 and PA4 are not strictly 180°.

[0048] Solution 2: Use two differential DAC (digital-to-analog converter) solutions, such as Figure 6 As shown. Specifically: configure two DA chips through the CPU bus to perform DA conversion according to the sine wave, and then control the DA chip to load data or start through the two IO ports of the CPU, so that the sine signal PA1 output by DA1 is orthogonal to the sine signal PA3 output by DA2 (the phase difference is 90°). At the same time, since DA1 and DA2 are differential output chips, the output signal PA2 is strictly inverse to the signal PA1, and the signal PA4 is also strictly inverse to the signal PA3.

[0049] Solution 2 uses two pairs of differential DA converters to realize four orthogonal sinusoidal signals; each DA outputs a pair of differential signals, and the differential signals output by the two DAs are orthogonal to each other.

[0050] Advantages of this solution: Compared with Figure 5The phase difference of this solution is more accurate.

[0051] The second part of the signal amplification circuit has two specific implementation schemes:

[0052] Solution 1: The four orthogonal low-voltage sinusoidal signals PA1-PA4 generated by the low-voltage sinusoidal signal generating circuit are first amplified by four high-voltage operational amplifiers OP1-OP4 to obtain four orthogonal high-voltage sinusoidal signals PB1-PB4, and then passed through the first group of four single-pole double-throw analog switches. Here, the analog switches are reversed, and the signals PB1-PB4 are respectively connected to channel 1 of the double-throw end of the first group of four analog switches, and the channels 2 of the four double-throw ends are all connected to the ground signal GND. At the same time, the signals PB1-PB4 are branched to channel 2 of the double-throw end of the second group of four analog switches, and the channels 1 of the double-throw end of the second group of four analog switches are all connected to the ground signal GND. When the two groups of four analog switches are switched to channel 1, the single-pole end of the first group of analog switches outputs four orthogonal high-voltage sinusoidal signals PC1-PC4 respectively, and the single-pole ends QC1-QC4 of the second group of analog switches are all grounded. Conversely, when both sets of four-way analog switches are switched to channel 2, the single-pole terminals PC1-PC4 of the first set of analog switches are grounded, and the single-pole terminals QC1-QC4 of the second set of analog switches output four orthogonal high-voltage sinusoidal signals respectively. Figure 7 shown.

[0053] In scheme 1, the excitation signal is amplified and filtered before switching the signal channel through a high-voltage analog switch to achieve time-sharing excitation. At the same time, the other contact of the switch is grounded to avoid crosstalk due to suspension; the analog switch power supply voltage VDD is greater than 10V.

[0054] Advantages of this solution: Compared with Figure 3 The solution does not need to copy the four orthogonal low-voltage sinusoidal signals generated by the low-voltage sinusoidal signal generating circuit, but only needs to be switched through analog switches. Figure 4 In this solution, the other channel of the analog switch will not be left floating, the signal state is determined, and it is not easily disturbed.

[0055] Disadvantages of this solution: Since an 8-way single-pole double-throw high-voltage analog switch is required, and high-voltage analog switches are not conventional general-purpose devices, there are fewer models to choose from and the cost is relatively high.

[0056] Solution 2: Connect the four orthogonal low-voltage sinusoidal signals PA1-PA4 generated by the low-voltage sinusoidal signal generating circuit to channel 1 of the double-throw end of the first group of four single-pole double-throw analog switches, and connect channel 2 of the double-throw end of the first group of four analog switches to the ground signal GND. At the same time, connect the signals PA1-PA4 to channel 2 of the double-throw end of the second group of four analog switches, and connect channel 1 of the double-throw end of the second group of four analog switches to the ground signal GND. When the two groups of four analog switches are switched to channel 1, the single-pole end of the first group of analog switches outputs four orthogonal low-voltage sinusoidal signals, and the four high-voltage operational amplifiers OP1-OP4 amplify the signals to obtain four orthogonal high-voltage sinusoidal signals PB1-PB4. The single-pole end of the second group of analog switches is still all ground signal GND, and the output QB1-QB4 after amplification by the four high-voltage operational amplifiers OP5-OP8 is still ground. On the contrary, when the two groups of four analog switches are switched to channel 2, the four output signals PB1-PB4 of the first group are all grounded, and the four output signals QB1-QB4 of the second group are four orthogonal high-voltage sinusoidal signals. Figure 8 shown.

[0057] Solution 2 uses a low-voltage (below 5V) analog switch to switch the signal channel, and at the same time grounds the other contact of the switch to avoid crosstalk due to suspension (the analog switch power supply voltage VDD is less than 5V); the switched signal is then amplified and filtered to achieve the purpose of time-sharing high-voltage excitation output.

[0058] Advantages of this solution: Figure 7 While the solution has advantages, it does not require the use of Figure 7 Instead of using a high-voltage analog switch, you can use a low-voltage analog switch. Low-voltage analog switches are conventional general-purpose devices with a large number of optional models, greater selection flexibility, and lower cost.

[0059] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described with reference to the preferred embodiments of the present invention, it should be understood by those skilled in the art that various changes may be made in form and details without departing from the spirit and scope of the present invention as defined in the appended claims.

Claims

1. Time-sharing orthogonal high-voltage excitation circuit structure, including A low-voltage sinusoidal signal generating circuit, used for generating four orthogonal low-voltage sinusoidal signals PA1-PA4; The signal amplifier circuit is used to amplify four orthogonal low-voltage sinusoidal signals to obtain the required high voltage; it is characterized by: The signal amplification circuit includes two groups of four-way single-pole double-throw analog switches and eight-way high-voltage operational amplifiers; The four orthogonal low-voltage sinusoidal signals PA1-PA4 output by the low-voltage sinusoidal signal generating circuit are respectively connected to channel 1 of the double-throw end of the first group of four single-pole double-throw analog switches, and channel 2 of the double-throw end of the first group of four single-pole double-throw analog switches is all grounded; the four orthogonal low-voltage sinusoidal signals PA1-PA4 output by the low-voltage sinusoidal signal generating circuit are simultaneously connected to channel 2 of the double-throw end of the second group of four single-pole double-throw analog switches, and channel 1 of the double-throw end of the second group of four single-pole double-throw analog switches is all grounded; the single-pole ends of all single-pole double-throw analog switches are respectively connected to high-voltage operational amplifiers as output ends to amplify the output signals.

2. The time-sharing orthogonal high-voltage excitation circuit structure according to claim 1 is characterized in that: The power supply voltage VDD of the SPDT analog switch is less than 5V.

3. The time-sharing orthogonal high-voltage excitation circuit structure according to claim 1 is characterized in that: The low-voltage sinusoidal signal generating circuit includes a CPU, two digital-to-analog converters and two inverting operational amplifiers. The bus of the CPU is simultaneously connected to the two digital-to-analog converters so that the two digital-to-analog converters perform DA conversion according to a sinusoidal wave. The two IO ports of the CPU are respectively connected to the two digital-to-analog converters to control the two digital-to-analog converters to load data or start, so that the sinusoidal signals output by the two digital-to-analog converters are orthogonal; the sinusoidal signal PA1 output by one digital-to-analog converter is connected to the inverting operational amplifier 1, and a sinusoidal signal PA2 with the same frequency and amplitude as the sinusoidal signal PA1 but opposite phase is obtained at the output end of the inverting operational amplifier 1; the sinusoidal signal PA3 output by the other digital-to-analog converter is connected to the inverting operational amplifier 2, and a sinusoidal signal PA4 with the same frequency and amplitude as the sinusoidal signal PA3 but opposite phase is obtained at the output end of the inverting operational amplifier 2; the sinusoidal signals PA1, PA2, PA3 and PA4 constitute the four orthogonal low-voltage sinusoidal signals.

4. The time-sharing orthogonal high-voltage excitation circuit structure according to claim 1 is characterized in that: The low-voltage sinusoidal signal generating circuit includes a CPU and two differential digital-to-analog converters. The bus of the CPU is simultaneously connected to the two differential digital-to-analog converters so that the two differential digital-to-analog converters perform DA conversion according to a sinusoidal wave. The two IO ports of the CPU are respectively connected to the two differential digital-to-analog converters to control the two differential digital-to-analog converters to load data or start, so that the sinusoidal signals output by the two differential digital-to-analog converters are orthogonal; one of the differential digital-to-analog converters outputs two sinusoidal signals PA1 and PA2 with opposite phases; the other differential digital-to-analog converter outputs two sinusoidal signals PA3 and PA4 with opposite phases; the sinusoidal signals PA1, PA2, PA3 and PA4 constitute the four orthogonal low-voltage sinusoidal signals.

5. Time-sharing orthogonal high-voltage excitation circuit structure, including A low-voltage sinusoidal signal generating circuit, used for generating four orthogonal low-voltage sinusoidal signals PA1-PA4; The signal amplifier circuit is used to amplify four orthogonal low-voltage sinusoidal signals to obtain the required high voltage; it is characterized by: The signal amplification circuit includes two groups of four-way single-pole double-throw analog switches and four-way high-voltage operational amplifiers; The four outputs of the low-voltage sinusoidal signal generating circuit are respectively connected to high-voltage operational amplifiers OP1-OP4 to amplify the four orthogonal low-voltage sinusoidal signals PA1-PA4 to obtain four orthogonal high-voltage sinusoidal signals PB1-PB4; The four high-voltage sinusoidal signals PB1-PB4 are respectively connected to channel 1 of the double-throw end of the first group of four single-pole double-throw analog switches, and channel 2 of the double-throw end of the first group of four single-pole double-throw analog switches are all grounded; the four high-voltage sinusoidal signals PB1-PB4 are simultaneously respectively connected to channel 2 of the double-throw end of the second group of four single-pole double-throw analog switches, and channel 1 of the double-throw end of the second group of four single-pole double-throw analog switches is all grounded; the single-pole ends of all single-pole double-throw analog switches are used as signal output ends.

6. The time-sharing orthogonal high-voltage excitation circuit structure according to claim 5 is characterized in that: The power supply voltage VDD of the SPDT analog switch is 10~36V.

7. The time-sharing orthogonal high-voltage excitation circuit structure according to claim 5 is characterized in that: The low-voltage sinusoidal signal generating circuit includes a CPU, two digital-to-analog converters and two inverting operational amplifiers. The bus of the CPU is simultaneously connected to the two digital-to-analog converters so that the two digital-to-analog converters perform DA conversion according to a sinusoidal wave. The two IO ports of the CPU are respectively connected to the two digital-to-analog converters to control the two digital-to-analog converters to load data or start, so that the sinusoidal signals output by the two digital-to-analog converters are orthogonal; the sinusoidal signal PA1 output by one digital-to-analog converter is connected to the inverting operational amplifier 1, and a sinusoidal signal PA2 with the same frequency and amplitude as the sinusoidal signal PA1 but opposite phase is obtained at the output end of the inverting operational amplifier 1; the sinusoidal signal PA3 output by the other digital-to-analog converter is connected to the inverting operational amplifier 2, and a sinusoidal signal PA4 with the same frequency and amplitude as the sinusoidal signal PA3 but opposite phase is obtained at the output end of the inverting operational amplifier 2; the sinusoidal signals PA1, PA2, PA3 and PA4 constitute the four orthogonal low-voltage sinusoidal signals.

8. The time-sharing orthogonal high-voltage excitation circuit structure according to claim 5 is characterized in that: The low-voltage sinusoidal signal generating circuit includes a CPU and two differential digital-to-analog converters. The bus of the CPU is simultaneously connected to the two differential digital-to-analog converters so that the two differential digital-to-analog converters perform DA conversion according to a sinusoidal wave. The two IO ports of the CPU are respectively connected to the two differential digital-to-analog converters to control the two differential digital-to-analog converters to load data or start, so that the sinusoidal signals output by the two differential digital-to-analog converters are orthogonal; one of the differential digital-to-analog converters outputs two sinusoidal signals PA1 and PA2 with opposite phases; the other differential digital-to-analog converter outputs two sinusoidal signals PA3 and PA4 with opposite phases; the sinusoidal signals PA1, PA2, PA3 and PA4 constitute the four orthogonal low-voltage sinusoidal signals.

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