Rotary transformer excitation circuit and rotary transformer drive system

Abstract

The utility model discloses a rotary transformer excitation circuit and a rotary transformer drive system, and relates to the technical field of rotary transformer decoding, and the rotary transformer excitation circuit comprises a main control module which is used for outputting a single-side excitation signal; the power amplifier bias module is connected with the main control module and is used for carrying out amplitude amplification and bias processing on the single-side excitation signal and outputting a first excitation processing signal; the push-pull module is connected with the power amplifier bias module and is used for performing power amplification processing on the first excitation processing signal and outputting a second excitation processing signal; and the direct current blocking module is connected with the push-pull module and is used for carrying out direct current blocking processing on the second excitation processing signal to obtain a single-side excitation driving signal so as to drive the rotary transformer to work. According to the rotary transformer excitation circuit, the structure is simple, and the economic cost of a rotary transformer drive system is reduced.

Description

Technical Field

[0001] The present application relates to the technical field of resolver decoding, and in particular to a resolver excitation circuit and a resolver electric drive system. Background Art

[0002] In the electric drive system of new energy vehicles, resolver software can be used to decode the resolver position. The resolver software decoding needs to match the corresponding excitation amplifier circuit. In related technologies, two excitation signals are usually respectively passed through an operational amplifier for amplitude gain, and then respectively passed through a first-level push-pull for power amplification. The AC component required by the resolver can be obtained by subtracting the two.

[0003] However, the above method requires processing of bilateral excitation signals, which requires a large number of circuit components, resulting in excessively high overall cost of the electric drive system for new energy vehicles. Utility Model Content

[0004] The main purpose of the present application is to provide a resolver excitation circuit and a resolver electric drive system, aiming to solve the technical problem of high cost of electric drive systems in related technologies.

[0005] To achieve the above objectives, the present application proposes a resolver excitation circuit, comprising:

[0006] Main control module, used to output unilateral excitation signal;

[0007] A power amplifier bias module is connected to the main control module and is used to amplify the amplitude and bias the unilateral excitation signal and output a first excitation processing signal;

[0008] A push-pull module, connected to the power amplifier bias module, for performing power amplification processing on the first excitation processing signal and outputting a second excitation processing signal;

[0009] The DC isolation module is connected to the push-pull module and is used to perform DC isolation processing on the second excitation processing signal to obtain a single-sided excitation driving signal to drive the rotary transformer to work.

[0010] In one embodiment, the power amplifier bias module includes an operational amplifier unit, an inverting input unit, and a non-inverting input unit;

[0011] One end of the positive phase input unit is connected to the main control module, and the other end of the positive phase input unit is connected to the positive phase input end of the operational amplifier unit, and the positive phase input unit is used to provide a positive phase input signal to the operational amplifier unit;

[0012] One end of the inverting input unit is connected to the main control module, and the other end of the inverting input unit is connected to the inverting input end of the operational amplifier unit. The inverting input unit is used to filter the unilateral excitation signal and provide an inverting input signal to the operational amplifier unit.

[0013] The output end of the operational amplifier unit is connected to the push-pull module, and the feedback end of the operational amplifier unit is respectively connected to the push-pull module and the DC isolation module. The operational amplifier unit is used to generate and output a first excitation processing signal according to an inverting input signal and a non-phase input signal.

[0014] In one embodiment, the inverting input unit includes a resistor R14, a resistor R15 and a capacitor C12;

[0015] One end of the resistor R14 is connected to the main control module, the other end of the resistor R14 is respectively connected to one end of the resistor R15 and one end of the capacitor C12, the other end of the resistor R15 is respectively connected to the inverting input end of the operational amplifier unit, and the other end of the capacitor C12 is grounded.

[0016] In one embodiment, the non-phase input unit includes a resistor R18, a resistor R20, a capacitor C7 and a capacitor C8;

[0017] One end of the resistor R18 is connected to the main control module, the other end of the resistor R18 is respectively connected to one end of the capacitor C7 and one end of the resistor R20, the other end of the capacitor C7 is connected to the first external power supply, the other end of the resistor R20 is respectively connected to one end of the capacitor C8 and the non-inverting input end of the operational amplifier unit, and the other end of the capacitor C8 is grounded.

[0018] In one embodiment, the operational amplifier unit includes a first operational amplifier, a resistor R9 and a capacitor C9; the slew rate of the first operational amplifier is not less than 0.613 V / μs;

[0019] The inverting input terminal of the first operational amplifier is respectively connected to the other end of the resistor R15, one end of the resistor R9 and one end of the capacitor C9, the non-inverting input terminal of the first operational amplifier is connected to the other end of the resistor R20, the output terminal of the first operational amplifier is respectively connected to the other end of the capacitor C9 and the push-pull module, and the other end of the resistor R9 is respectively connected to the push-pull module and the DC isolation module.

[0020] In one embodiment, the push-pull module includes a first push-pull unit and a second push-pull unit; the first push-pull unit includes a resistor R10, a resistor R11, a resistor R13, a diode D6 and a transistor Q2; the second push-pull unit includes a resistor R19, a resistor R21, a resistor R17, a diode D9, and a transistor Q3;

[0021] The cathode of diode D6 is respectively connected to the anode of diode D9 and the output end of the operational amplifier unit, the anode of diode D6 is respectively connected to the base of transistor Q2 and one end of resistor R10 through resistor R11, the other end of resistor R10 is respectively connected to the collector of transistor Q2 and the second external power supply, the emitter of transistor Q2 is respectively connected to one end of resistor R17, the feedback end of the operational amplifier unit and the DC isolation module through resistor R13, the cathode of diode D9 is respectively connected to the base of transistor Q3 and one end of resistor R21 through resistor R19, the emitter of transistor Q3 is connected to the other end of resistor R17, and the other end of resistor R21 and the collector of transistor Q3 are grounded.

[0022] In one embodiment, the push-pull module further includes a first current limiting unit and a second current limiting unit; the first current limiting unit and the second current limiting unit each include at least one current limiting diode connected in series;

[0023] One end of the first current limiting unit is connected to the base of the transistor Q2, the other end of the first current limiting unit is respectively connected to one end of the second current limiting unit, the common point of the resistor R13 and the resistor R17, and the other end of the second current limiting unit is connected to the base of the transistor Q3.

[0024] In addition, to achieve the above-mentioned purpose, the present application also proposes a resolver electric drive system, the resolver electric drive system comprising:

[0025] Such as the resolver excitation circuit mentioned above;

[0026] A common mode excitation circuit is connected to the resolver excitation circuit and is used to generate a first excitation differential drive signal and a second excitation differential drive signal according to a unilateral excitation drive signal output by the resolver excitation circuit;

[0027] The rotary transformer is connected to the common mode excitation circuit and is used to operate according to the first excitation differential drive signal and the second excitation differential drive signal.

[0028] In one embodiment, the resolver electric drive system further includes an excitation recovery circuit, and the excitation recovery circuit includes:

[0029] The first feedback module is connected to the first output end of the common mode excitation circuit, the second output end of the common mode excitation circuit and the main control module of the resolver excitation circuit respectively, and the first feedback module is used to adjust the amplitude of the first excitation differential drive signal and the second excitation differential drive signal for the main control module to perform amplitude verification;

[0030] The second feedback module is respectively connected to the first output end of the common-mode excitation circuit, the second output end of the common-mode excitation circuit and the main control module of the resolver excitation circuit. The second feedback module is used to perform zero-crossing comparison on the first excitation differential drive signal and the second excitation differential drive signal for the main control module to perform frequency verification.

[0031] In one embodiment, the first feedback module includes a second operational amplifier, a resistor R34, a resistor R35, a resistor R36, a resistor R37 and a capacitor C25;

[0032] One end of the resistor R35 is connected to the second output end of the common-mode excitation circuit, the other end of the resistor R35 is respectively connected to one end of the capacitor C25, one end of the resistor R34 and the inverting input end of the second operational amplifier, one end of the resistor R36 is connected to the first output end of the common-mode excitation circuit, the other end of the resistor R36 is respectively connected to one end of the resistor R37 and the non-inverting input end of the second operational amplifier, the other end of the resistor R37 is connected to the reference power supply, and the output end of the second operational amplifier is respectively connected to the other end of the capacitor C25, the other end of the resistor R34 and the main control module;

[0033] The second feedback module includes a third operational amplifier, a resistor R38, a resistor R39, a resistor R40, a resistor R41 and a resistor R42;

[0034] One end of resistor R41 is connected to the first output end of the common-mode excitation circuit, the other end of resistor R41 is respectively connected to one end of resistor R40 and the non-inverting input end of the third operational amplifier, the other end of resistor R40 is connected to the second external power supply, one end of resistor R42 is connected to the second output end of the common-mode excitation circuit, the other end of resistor R42 is respectively connected to one end of resistor R39 and the inverting input end of the third operational amplifier, the other end of resistor R39 is connected to the other end of resistor R40, the output end of the third operational amplifier is respectively connected to one end of resistor R38 and the main control module, and the other end of resistor R38 is connected to the first external power supply.

[0035] One or more technical solutions proposed in this application have at least the following technical effects:

[0036] The present application provides a resolver excitation circuit and a resolver electric drive system. The resolver excitation circuit includes a main control module, which can be used to output a unilateral excitation signal; a power amplifier bias module, which is connected to the main control module and can be used to amplify the amplitude and bias the unilateral excitation signal to output a first excitation processing signal; a push-pull module, which is connected to the power amplifier bias module and can be used to amplify the power of the first excitation processing signal to output a second excitation processing signal; and a DC isolation module, which is connected to the push-pull module and can be used to isolate the second excitation processing signal to obtain a unilateral excitation drive signal to drive the resolver to work.

[0037] The present application only needs to amplify the unilateral excitation signal to obtain the unilateral excitation drive signal for driving the rotary transformer, without having to amplify the two excitation signals separately through an operational amplifier and a first-stage push-pull and then subtract the two to obtain the AC component required by the rotary transformer, thereby reducing the construction cost of the electric drive system. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present application and, together with the description, serve to explain the principles of the present application.

[0039] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the related technologies, the drawings required for use in the embodiments or the related technical descriptions are briefly introduced below. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0040] Figure 1 This is a structural schematic diagram of a first embodiment of a resolver excitation circuit of the present application;

[0041] Figure 2 This is a detailed structural diagram of the first embodiment of the resolver excitation circuit of the present application;

[0042] Figure 3 This is a detailed circuit schematic diagram of the resolver excitation circuit of this application;

[0043] Figure 4 This is a schematic diagram of the structure of the first embodiment of the resolver electric drive system of the present application;

[0044] Figure 5 This is a detailed circuit diagram of the excitation recovery circuit of this application;

[0045] Figure 6 is a schematic diagram of the structure of an example resolver decoding system;

[0046] Figure 7 It is a structural schematic diagram of the power module of the resolver decoding system;

[0047] Figure 8 is a schematic diagram of an output waveform of an exemplary decoding circuit;

[0048] Fig. 9 Schematic diagram of the rotating transformer winding current waveform.

[0049] The realization of the purpose, functional features and advantages of this application will be further explained in conjunction with embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0050] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0051] It should be noted that if the embodiments of the present application involve directional indications (such as up, down, left, right, front, back, etc.), the directional indications are only used to explain the relative position relationship, movement status, etc. between the components in a certain specific posture. If the specific posture changes, the directional indication will also change accordingly.

[0052] In addition, if there are descriptions involving "first", "second", etc. in the embodiments of the present application, the descriptions of "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of technical features indicated. Therefore, the features limited to "first" and "second" may explicitly or implicitly include at least one of the features. In addition, if "and / or" or "and / or" appears in the full text, its meaning includes three parallel schemes. Taking "A and / or B" as an example, it includes scheme A, or scheme B, or a scheme that satisfies both A and B. In addition, the technical solutions between the various embodiments can be combined with each other, but it must be based on the ability of ordinary technicians in the field to implement. When the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection required by this application.

[0053] In the electric drive system of new energy vehicles, the position and speed of the motor rotor will participate in the closed-loop control of the permanent magnet synchronous motor in real time. The accuracy of its measurement is a key technology for high-performance electric drive systems. The resolver is an electromagnetic sensor with the advantages of simple structure, sensitive action, and strong anti-electromagnetic interference ability. It is particularly suitable for the field of automotive drive. The general resolver decoding method is to use a dedicated decoding chip, such as the AU68x series, AD2S series and other decoding chips. Although these decoding chips have excellent performance, integrating excitation generation, signal conditioning and signal decoding, and have high integration, the price of dedicated decoding chips is relatively high, which increases the system cost. For this reason, a software decoding method is proposed, that is, without using a dedicated decoding chip, only using the peripheral resources of the main control chip, and decoding the resolver position by pure software.

[0054] Resolver software decoding usually requires matching the corresponding excitation circuit and feedback signal conditioning circuit, and the excitation circuit is the core of the resolver decoding circuit. In related technologies, the two excitation signals A and B can be respectively passed through an operational amplifier for amplitude gain, and then passed through a first-stage push-pull for power amplification, and then the two are subtracted to jointly provide the AC component required for excitation of the resolver.

[0055] However, the above method requires processing of both bilateral excitation signals, and requires the use of numerous circuit components, which will result in excessively high overall cost of the electric drive system.

[0056] In order to solve this technical problem, a rotary transformer excitation circuit of the present application is proposed, in which a unilateral excitation signal is generated by a main control module, and a power amplifier bias module connected to the main control module can amplify the amplitude and bias the unilateral excitation signal. The first excitation processing signal obtained by processing is amplified by a push-pull module connected to the power amplifier bias module to obtain a second excitation processing signal; the DC component in the second excitation processing signal can be filtered out by a DC isolation module connected to the push-pull module to obtain a unilateral excitation drive signal for driving the rotary transformer. All the AC components required by the rotary transformer can be obtained by amplifying the unilateral excitation signal, and the circuit is simplified, which can effectively reduce the cost of the electric drive system.

[0057] The following will describe and introduce the invention through multiple embodiments.

[0058] See also Figure 1 , Figure 1 This is a structural schematic diagram of embodiment 1 of the resolver excitation circuit of the present application.

[0059] In this embodiment, the resolver excitation circuit includes:

[0060] Main control module, used to output unilateral excitation signal;

[0061] A power amplifier bias module is connected to the main control module and is used to amplify the amplitude and bias the unilateral excitation signal and output a first excitation processing signal;

[0062] A push-pull module, connected to the power amplifier bias module, for performing power amplification processing on the first excitation processing signal and outputting a second excitation processing signal;

[0063] The DC isolation module is connected to the push-pull module and is used to perform DC isolation processing on the second excitation processing signal to obtain a single-sided excitation driving signal to drive the rotary transformer to work.

[0064] Specifically, the main control module can be a main control chip that integrates a microcontroller, a signal generator and other devices. The microcontroller can generate a unilateral excitation drive signal of the required frequency and amplitude according to a preset program. For example, the main control chip can be an Infineon TC3xx series chip. The power amplifier bias module connected to the main control module can perform amplitude amplification and bias processing on the unilateral excitation signal, so that the amplitude of the unilateral excitation drive signal can meet the amplitude requirement for driving the rotary transformer. The bias processing can ensure that the power amplifier bias module is in the correct linear working range, so as to effectively perform amplitude amplification processing on the unilateral excitation signal.

[0065] In one possible implementation, refer to Figure 2 , Figure 2 The detailed structural diagram of the first embodiment of the resolver excitation circuit of the present application is shown. In this embodiment, the power amplifier bias module may include an operational amplifier unit, an inverting input unit and a non-inverting input unit;

[0066] One end of the positive phase input unit is connected to the main control module, and the other end of the positive phase input unit is connected to the positive phase input end of the operational amplifier unit, and the positive phase input unit is used to provide a positive phase input signal to the operational amplifier unit;

[0067] One end of the inverting input unit is connected to the main control module, and the other end of the inverting input unit is connected to the inverting input end of the operational amplifier unit. The inverting input unit is used to filter the unilateral excitation signal and provide an inverting input signal to the operational amplifier unit.

[0068] The output end of the operational amplifier unit is connected to the push-pull module, and the feedback end of the operational amplifier unit is respectively connected to the push-pull module and the DC isolation module. The operational amplifier unit is used to generate and output a first excitation processing signal according to an inverting input signal and a non-phase input signal.

[0069] Specifically, the positive phase input unit of the power amplifier bias module is connected to the main control module, and the main control module can generate a modulation signal, such as a main control chip can generate a PWM signal (pulse width modulation signal). The PWM signal can filter out some high-frequency components through the positive phase input unit, retain its DC component, and ensure that the PWM signal can be smoothed into a voltage output close to DC, providing a positive phase input signal for the operational amplifier unit. The negative phase input unit of the power amplifier bias module is connected to the main control module, and can filter the unilateral excitation signal output by the main control module, and the filtered signal can be used as the negative phase input signal of the operational amplifier unit. The operational amplifier unit can realize the amplitude amplification and bias processing of the unilateral excitation signal according to the positive phase input signal and the negative phase input signal to generate a first excitation processing signal.

[0070] In one possible implementation, refer to Figure 3 , Figure 3The detailed circuit diagram of the rotary transformer excitation circuit of the present application is shown. Figure 3 As shown, the inverting input unit may include a resistor R14, a resistor R15 and a capacitor C12;

[0071] One end of the resistor R14 is connected to the main control module, the other end of the resistor R14 is respectively connected to one end of the resistor R15 and one end of the capacitor C12, the other end of the resistor R15 is respectively connected to the inverting input end of the operational amplifier unit, and the other end of the capacitor C12 is grounded.

[0072] Specifically, the combination of resistor R14, resistor R15 and capacitor C12 can achieve preliminary filtering of the unilateral excitation signal. Compared with directly using a capacitor for filtering at the inverting input end, this structure can solve the problem that low-frequency signals cannot pass through, and can also reduce the difficulty of filter design.

[0073] The positive phase input unit may include a resistor R18, a resistor R20, a capacitor C7, and a capacitor C8;

[0074] One end of the resistor R18 is connected to the main control module, the other end of the resistor R18 is respectively connected to one end of the capacitor C7 and one end of the resistor R20, the other end of the capacitor C7 is connected to the first external power supply, the other end of the resistor R20 is respectively connected to one end of the capacitor C8 and the non-inverting input end of the operational amplifier unit, and the other end of the capacitor C8 is grounded.

[0075] Specifically, the positive phase input unit can convert the PWM signal generated by the main control module into a DC voltage. Figure 3 As shown in the figure, the PWM signal of the main control module can reach the positive input terminal of the operational amplifier unit after passing through the second-order RC filter composed of R18 / C7 and R20 / C8. The cutoff frequency f of the positive input unit during filtering is s It can be expressed as: It should be noted that in practical applications, the values ​​of R18, C7, R20 and C8 should not be too small, so that the cut-off frequency can be much lower than the frequency of the PWM signal, so that the PWM signal can be converted into a DC voltage. Although the load capacity of the DC voltage is relatively weak, it is still suitable for the operational amplifier unit. Compared with the first-order filter, the second-order filter can reduce the delay of voltage conversion and greatly reduce the ripple voltage after conversion. The positive-phase input signal obtained after processing by the positive-phase input unit can be expressed as U in+ , U in+ =V 5P ×D; where D is the duty cycle of the PWM signal output by the main control module, V 5P It is the first external power supply with an amplitude of 5V.

[0076] The operational amplifier unit may include a first operational amplifier, a resistor R9 and a capacitor C9; the slew rate of the first operational amplifier is not less than 0.613 V / μs;

[0077] The inverting input terminal of the first operational amplifier IC2 ( Figure 3 The first operational amplifier IC2 (port 2) is connected to the other end of the resistor R15, one end of the resistor R9 and one end of the capacitor C9 respectively. The positive input terminal ( Figure 3 The output terminal (port 3 of the first operational amplifier IC2) of the first operational amplifier IC2 is connected to the other end of the resistor R20. Figure 3 Port 1 of the first operational amplifier IC2 is respectively connected to the other end of the capacitor C9 and the push-pull module, and the other end of the resistor R9 is respectively connected to the push-pull module and the DC isolation module.

[0078] Specifically, since the load of the resolver excitation circuit is a rotary transformer (with an inductive resolver winding inside), when the feedback signal of the resolver is subsequently conditioned, the feedback signal output by the resolver will lag behind the unilateral excitation signal in phase, so a capacitor C9 can be connected in parallel to the inverting input and output of the first operational amplifier IC2, and the capacitor C9 can achieve phase advance compensation to prevent the generation of self-excited oscillation. At the same time, the resistor R9 and the capacitor C9 can also form a second-order inverting low-pass active filter with the resistor R12 and the capacitor C12 in the inverting input unit to filter out high-frequency noise in the signal and enhance signal stability.

[0079] In addition, in the operational amplifier unit, the selection of the first operational amplifier IC2 is more important for the amplitude amplification of the unilateral excitation signal. The key indicator for the selection of the operational amplifier is its slew rate, which is also called the conversion rate. It can reflect the operational amplifier's ability to respond to rapidly changing signals. If the slew rate of the operational amplifier does not meet the standard, the output signal may be severely distorted. The unilateral excitation signal output by the main control module is generally a standard 10kHz sinusoidal signal. The slew rate required for the 10kHz unilateral excitation signal is at least 0.613V / μs. Preferably, the slew rate of the operational amplifier can have a 2-fold margin of 0.613V / μs. The operational amplifier can withstand a supply voltage of 30V (i.e. Figure 3 The first op amp is connected to V 30P driving power supply).

[0080] Under the above circuit structure, the output voltage U of the first operational amplifier IC2 is out (i.e., the first excitation processing signal) can be expressed as:

[0081]

[0082] In the above formula, when Uin- The inverting input signal is a 10kHz sine wave. in- =2.5+2.5sin(2π×10000t); U in+ is the positive phase input signal, U in+ =V 5P ×D; change U in- and U in+ Substitute the above U out The expression can be obtained:

[0083] U out =-2.5G·sin(2π×10000t)+(5D-2.5)·G+5D; where G is

[0084] Amplitude gain, As can be seen from the above formula, the resistors R9, R14 and R15 with appropriate resistance values ​​can be selected to adjust the amplitude gain so that the unilateral excitation signal can provide all the AC components required by the rotary transformer excitation coil after passing through the operational amplifier unit. And by adjusting the duty cycle D of the PWM signal, the bias voltage output by the first operational amplifier IC2 can also be linearly adjusted so that the first operational amplifier can operate within the correct linear working range, ensuring that the unilateral excitation signal can be effectively amplified.

[0085] In order to enhance the driving capability of the unilateral excitation signal, a push-pull module can be added after the output end of the power amplifier bias module. The push-pull module is provided with a push-pull structure inside, which can effectively amplify the power of the first excitation processing signal to obtain the second excitation processing signal, so that the processed signal can drive a larger power load. Figure 3 As shown, the push-pull module may include a first push-pull unit and a second push-pull unit; the first push-pull unit includes a resistor R10, a resistor R11, a resistor R13, a diode D6 and a transistor Q2; the second push-pull unit includes a resistor R19, a resistor R21, a resistor R17, a diode D9, and a transistor Q3;

[0086] The cathode of diode D6 is respectively connected to the anode of diode D9 and the output end of the operational amplifier unit, the anode of diode D6 is respectively connected to the base of transistor Q2 and one end of resistor R10 through resistor R11, the other end of resistor R10 is respectively connected to the collector of transistor Q2 and the second external power supply, the emitter of transistor Q2 is respectively connected to one end of resistor R17, the feedback end of the operational amplifier unit and the DC isolation module through resistor R13, the cathode of diode D9 is respectively connected to the base of transistor Q3 and one end of resistor R21 through resistor R19, the emitter of transistor Q3 is connected to the other end of resistor R17, and the other end of resistor R21 and the collector of transistor Q3 are grounded.

[0087] Specifically, in the push-pull module, the forward voltage drops of the diodes D6 and D9 can offset the base-emitter dead zone voltage V of the transistors Q2 and Q3, respectively. BE , forming a pre-bias circuit. Ideally, when there is no signal input, the quiescent current of the transistor is almost 0, and the transistor does not heat up. The V BE It has a negative temperature coefficient characteristic that becomes smaller as the temperature increases. When a large amount of load current passes through it, the temperature of the transistor will increase, V BE The value of will become smaller. However, diodes D6 and D9 basically do not generate heat, and their forward voltage drops V F Almost a constant value, at this time V F >V BE The collector quiescent current of transistor Q2 and transistor Q3 is h FE ·(V F -V BE ), where h FE The collector static current directly passes through transistor Q2 and transistor Q3 in the second external power supply V 30P However, this further increases the collector static current. Such a cycle may cause thermal shock damage to the transistor. Therefore, resistors R13 and R17 can be connected to the emitters of transistors Q2 and Q3 respectively to absorb V F 、V BE The voltage difference between the collector and the F -V BE ) / R13. Resistors R11 and R19 can compensate for the voltage drops of resistors R13 and R17 respectively and can be used to fine-tune the pre-bias voltage. Resistors R10 and R21 can form a conduction loop with diodes D6 and D9 and provide bias current for the bases of transistors Q2 and Q3. In addition, the transistor Q2 can be an NPN transistor, and the transistor Q3 can be a PNP transistor.

[0088] After the unilateral excitation signal is amplified by the power amplifier bias module and amplified by the push-pull module, the second excitation processing signal obtained can be isolated by the DC isolation module connected to the push-pull module to filter out the DC component in the second excitation processing signal to obtain a unilateral excitation drive signal that can be used to drive the rotary transformer. The DC isolation module can be a chip with integrated DC isolation elements, or it can be a Figure 3 DC blocking capacitors C10 and C14 are shown.

[0089] In addition, the push-pull module may further include a first current limiting unit and a second current limiting unit; the first current limiting unit and the second current limiting unit each include at least one current limiting diode connected in series;

[0090] One end of the first current limiting unit is connected to the base of the transistor Q2, the other end of the first current limiting unit is respectively connected to one end of the second current limiting unit, the common point of the resistor R13 and the resistor R17, and the other end of the second current limiting unit is connected to the base of the transistor Q3.

[0091] Specifically, in order to deal with the short circuit anomaly of the excitation coil, a current limiting unit can be added to the push-pull module. Each current limiting unit includes at least one current limiting diode connected in series. Figure 3 As shown, the first current limiting unit may include a current limiting diode D3, a current limiting diode D4, a current limiting diode D5 and a current limiting diode D7, and the corresponding second current limiting unit may include a current limiting diode D8, a current limiting diode D10, a current limiting diode D11 and a current limiting diode D12. It should be noted that the number of diodes in the above-mentioned current limiting unit is set according to the actual application requirements, and there is no specific number limit. The multiple current limiting diodes in the current limiting unit are combined with the transistor Q2 and the transistor Q3 to form a current limiting overcurrent protection circuit; the transistor Q2 and the transistor Q3 are equivalent to adjustment tubes, the resistor R10 and the resistor R21 can provide the base current, the resistor R13 and the resistor R17 can prevent thermal breakdown, and can also be used as a current detection resistor. In normal operation, the current of the resolver excitation signal is less than 200mA, so the voltage drop on the current detection resistor is equal to the transistor junction voltage V BE The sum of the voltage drop on the current-limiting resistor and V Bm The sum exceeds the conduction voltage drop of the current limiting diode, the current limiting diode conducts, and automatically shunts the base current of the transistor, that is, the clamping effect of the current limiting diode allows the current of the transistor to be basically maintained constant, thereby playing the role of overcurrent protection, thereby being able to cope with abnormal situations such as short circuit of the excitation coil to the ground, short circuit to the power supply, and short circuit of the excitation windings to each other. Among them, the overcurrent protection threshold can be expressed as: I max =(n×V F -V BE ) / R13; In the above formula, n is the number of current limiting diodes in the current limiting unit, n≥2, and the value can be selected and matched according to the input impedance of the resolver in actual applications, and the typical value can be 3 to 5.

[0092] It can be seen that in the resolver excitation circuit provided in this embodiment, the power amplifier bias module and the push-pull module can respectively amplify the amplitude and power of the unilateral excitation signal generated by the main control module. The amplified signal is isolated by the DC isolation module to obtain a standard unilateral excitation drive signal to drive the resolver. The circuit is very streamlined, which can reduce the construction cost of the subsequent electric drive system.

[0093] Furthermore, the present application also proposes a resolver electric drive system, which comprises a common mode excitation circuit, a rotary transformer and the resolver excitation circuit. Figure 4 As shown, Figure 4 The specific structure of the resolver excitation circuit refers to the above embodiments. Since the rotary electric drive system of the present application adopts all the technical solutions of all the above embodiments, it has at least all the beneficial effects brought by the technical solutions of the above embodiments, which will not be described one by one here.

[0094] The common-mode excitation circuit is connected to the resolver excitation circuit, which can filter out the common-mode interference in the unilateral excitation drive signal and output the first excitation differential drive signal and the second excitation differential drive signal. Figure 3 As shown, the common-mode excitation circuit may include a common-mode inductor L2, a filter capacitor C11 and a filter capacitor C13. The input ends of the common-mode inductor L2 are connected to the DC isolation module, the first output end of the common-mode inductor L2 is respectively connected to one end of the filter capacitor C11 and the rotary transformer, the second output end of the common-mode inductor L2 is respectively connected to one end of the filter capacitor C13 and the rotary transformer, and the other end of the filter capacitor C11 and the other end of the filter capacitor C13 are both grounded. The rotary transformer is connected to the common-mode excitation circuit, and the first excitation differential drive signal ( Figure 3 EM_R1 and the second excitation differential drive signal ( Figure 3 EM_R2) to work.

[0095] In order to meet the higher level functional safety requirements of the resolver electric drive system, in a feasible implementation, the resolver electric drive system may further include an excitation recovery circuit, wherein the excitation recovery circuit may include:

[0096] The first feedback module is connected to the first output end of the common mode excitation circuit, the second output end of the common mode excitation circuit and the main control module of the resolver excitation circuit respectively, and the first feedback module is used to adjust the amplitude of the first excitation differential drive signal and the second excitation differential drive signal for the main control module to perform amplitude verification;

[0097] The second feedback module is respectively connected to the first output end of the common-mode excitation circuit, the second output end of the common-mode excitation circuit and the main control module of the resolver excitation circuit. The second feedback module is used to perform zero-crossing comparison on the first excitation differential drive signal and the second excitation differential drive signal for the main control module to perform frequency verification.

[0098] Specifically, the first feedback module can collect the output first excitation differential drive signal and the second excitation differential drive signal, and adjust the amplitude thereof. The amplitude-adjusted signal can be fed back to the main control module, and the main control module can verify whether the amplitude of the unilateral excitation drive signal meets the requirement. The second feedback module can collect the output first excitation differential drive signal and the second excitation differential drive signal, and perform zero-crossing comparison on them. After the main control module receives the square wave signal obtained by the zero-crossing comparison, it can verify whether the frequency of the unilateral excitation drive signal meets the requirement. When the amplitude and / or frequency are abnormal, the main control module can determine that the unilateral excitation drive signal is abnormal, thereby controlling the motor controller to enter the corresponding safety state according to the conditions to ensure the operating safety of the rotary transformer electric drive system.

[0099] In one possible implementation, referring to Figure 5 , Figure 5 This is a detailed circuit diagram of the excitation recovery circuit, such as Figure 5 As shown, the first feedback module may include a second operational amplifier IC3, a resistor R34, a resistor R35, a resistor R36, a resistor R37 and a capacitor C25;

[0100] One end of the resistor R35 is connected to the second output end of the common-mode excitation circuit, the other end of the resistor R35 is respectively connected to one end of the capacitor C25, one end of the resistor R34 and the inverting input end of the second operational amplifier IC3 (i.e., port No. 2 of IC3), one end of the resistor R36 is connected to the first output end of the common-mode excitation circuit, the other end of the resistor R36 is respectively connected to one end of the resistor R37 and the non-inverting input end of the second operational amplifier IC3 (i.e., port No. 3 of IC3), the other end of the resistor R37 is connected to the reference power supply, and the output end of the second operational amplifier IC3 (i.e., port No. 1 of IC3) is respectively connected to the other end of the capacitor C25, the other end of the resistor R34 and the main control module;

[0101] The second feedback module includes a third operational amplifier, a resistor R38, a resistor R39, a resistor R40, a resistor R41 and a resistor R42;

[0102] One end of resistor R41 is connected to the first output end of the common-mode excitation circuit, the other end of resistor R41 is respectively connected to one end of resistor R40 and the non-phase input end of the third operational amplifier IC4 (i.e., port 3 of IC4), the other end of resistor R40 is connected to the second external power supply, one end of resistor R42 is connected to the second output end of the common-mode excitation circuit, the other end of resistor R42 is respectively connected to one end of resistor R39 and the inverting input end of the third operational amplifier IC4 (i.e., port 2 of IC4), the other end of resistor R39 is connected to the other end of resistor R40, the output end of the third operational amplifier IC4 (i.e., port 1 of IC4) is respectively connected to one end of resistor R38 and the main control module, and the other end of resistor R38 is connected to the first external power supply.

[0103] The amplitude reduction coefficient of the first feedback module is R34 / R35, which can reduce the amplitude of the excitation differential drive signal to R34 / R35 times of the original amplitude. The main control module receives the signal with reduced amplitude ( Figure 5 After the EXC_FB1 in the output, the amplitude can be checked to determine whether the amplitude of the excitation drive signal meets the drive requirements. The second feedback module can perform zero-crossing comparison based on the first excitation differential drive signal and the second excitation differential drive signal, and the main control module receives the zero-crossing comparison signal ( Figure 5 After EXC_FB2 in the code, the period and rate of the signal can be derived by calculating the time interval between adjacent zero crossing points of the signal, thereby performing a frequency check on the excitation drive signal, so that the motor controller can be promptly controlled to enter a corresponding safe state when an abnormality occurs in the excitation drive signal.

[0104] It can be understood that in the resolver electric drive system provided in this embodiment, the resolver excitation circuit of the above embodiment is used to amplify the unilateral excitation signal to obtain an excitation drive signal for driving the rotary transformer. By using the above circuit, the system structure is simplified and the overall cost of the resolver electric drive system is reduced.

[0105] Based on the above design, we can get Figure 6 The resolver decoding system shown in FIG. Figure 6 As shown in the figure, after obtaining the excitation differential drive signal that meets the input requirements of the resolver, the resolver can be driven to operate, and the output winding of the resolver can send out a sine-cosine format signal containing the rotor position information, which can be transmitted back to the main control module (the main control module uses the Aurix TC377 chip) for decoding after passing through the feedback signal conditioning circuit, and finally the speed and position of the motor rotor are obtained. It should be noted that Figure 6The excitation amplifier circuit in the embodiment corresponds to the power amplifier bias module, push-pull module and DC isolation module in the resolver excitation circuit of the present application. In addition, in order to simplify the circuit structure, the driving power required by each circuit in the resolver decoding system can be integrated into a power module. The structural diagram of the power module is shown in FIG. Figure 7 As shown in the figure, in this power module, the KL30 voltage is the only power supply in the low-voltage area, and its typical operating voltage range is 9V to 16V. In order to pass the ISO 16750 low-voltage electrical load test, the low-voltage power supply system of the controller generally needs to cover the limit voltage of 6V to 28V. Figure 7 As shown, the KL30 voltage enters the system after reverse protection and filtering. The TLF35584 power management chip can generate multiple 5V power supplies required by the electric drive system. Among them, the first 5V voltage V5P_D can be converted to 1.25V V1P25 voltage through Buck step-down conversion, and then used together with V5P_D to power the main control chip; the second 5V voltage V5P_Ref can be converted to 1.67V V1P67_Ref reference voltage through step-down and other conversions; the third 5V voltage V5P_T1 can be used together with the reference voltage V1P67_Ref to power the feedback signal conditioning circuit (i.e., signal conditioning power supply); the remaining 5V signals (such as V5P_T1 and V5P_COM, etc.) can be used to power other modules of the electric drive.

[0106] Through Boost conversion, the KL30 voltage can be increased to 30V, and further input to the MPQ3910 boost regulator for voltage stabilization, so that the wide input KL30 voltage can be uniformly increased to a stable voltage (for example: 30V), and the 30V power supply can be used for the excitation amplifier circuit, and after Push-Pull processing, the 30V power supply can be used for the IGBT drive circuit in the decoding system; and through the LDO low-voltage dropout linear regulator, the KL30 voltage can be stabilized to a lower output voltage V5P_BB to drive the IGBT. In addition, the above-mentioned power module is also equipped with a KL30 sampling static current control, which can monitor the KL30 current state so as to decide whether to cut off the power supply when necessary.

[0107] By adopting the method of unifying the power supply of the resolver excitation circuit and the IGBT drive circuit, the power supply architecture is relatively streamlined, fewer electronic components are required, and the economy is better.

[0108] In addition, in order to verify the effectiveness of the circuit structure of the present application, the resolver decoding system including the resolver excitation circuit was made into a circuit board for a decoding experiment of the resolver. The main control module in the experiment is an Aurix microcontroller, and the resolver used is a four-pole magnetoresistive resolver with a transformation ratio of 0.177. The DSADC module in the Aurix microcontroller can generate an SPWM signal with a carrier frequency of 312.5kHz and a signal frequency of 9.765kHz. After low-pass filtering on the board side, a standard excitation sine wave with an amplitude of 5V can be obtained. However, this amplitude is not enough to drive an automotive resolver with a rated input of 7V. After the 5V standard excitation sine wave is connected to the above-mentioned resolver excitation circuit and combined with the decoding circuit, the decoding circuit output waveform can be obtained as shown below: Figure 8 As shown, Figure 8 Channel 1 is the voltage waveform of the excitation drive signal output by the decoder board. The peak-to-peak value is 20.05V, which is consistent with the design value (that is, it can be used to drive the rotary transformer). Channel 2 is the excitation SPWM issued by DSADC (main control chip), and channel 3 is the sine and cosine signal received by the DSADC port. The peak-to-peak value is 2.96V, which meets the input requirements of the main control chip. Fig. 9 The experimental results show that when the excitation winding of the rotary transformer is abnormally short-circuited (short-circuited to the power supply, short-circuited to the ground, or short-circuited between windings), the winding current is limited to below 259mA, verifying the effectiveness of the short-circuit unit in the push-pull module.

[0109] The above descriptions are only some embodiments of the present application, and are not intended to limit the patent scope of the present application. All equivalent structural changes made using the contents of the present application specification and drawings under the technical concept of the present application, or direct / indirect applications in other related technical fields are included in the patent protection scope of the present application.

Claims

1. A resolver excitation circuit, characterized in that: The resolver excitation circuit comprises: Main control module, used to output unilateral excitation signal; A power amplifier bias module, connected to the main control module, for performing amplitude amplification and bias processing on the unilateral excitation signal, and outputting a first excitation processing signal; A push-pull module, connected to the power amplifier bias module, configured to perform power amplification processing on the first excitation processing signal and output a second excitation processing signal; The DC isolation module is connected to the push-pull module and is used to perform DC isolation processing on the second excitation processing signal to obtain a single-sided excitation drive signal to drive the rotary transformer to work.

2. The resolver excitation circuit according to claim 1, characterized in that: The power amplifier bias module includes an operational amplifier unit, an inverting input unit and a non-inverting input unit; One end of the positive phase input unit is connected to the main control module, and the other end of the positive phase input unit is connected to the positive phase input end of the operational amplifier unit, and the positive phase input unit is used to provide a positive phase input signal to the operational amplifier unit; One end of the inverting input unit is connected to the main control module, and the other end of the inverting input unit is connected to the inverting input end of the operational amplifier unit. The inverting input unit is used to filter the unilateral excitation signal and provide an inverting input signal to the operational amplifier unit. The output end of the operational amplifier unit is connected to the push-pull module, and the feedback end of the operational amplifier unit is respectively connected to the push-pull module and the DC isolation module. The operational amplifier unit is used to generate and output the first excitation processing signal according to the inverting input signal and the positive input signal.

3. The resolver excitation circuit according to claim 2, characterized in that: The inverting input unit includes a resistor R14, a resistor R15 and a capacitor C12; One end of the resistor R14 is connected to the main control module, the other end of the resistor R14 is respectively connected to one end of the resistor R15 and one end of the capacitor C12, the other end of the resistor R15 is respectively connected to the inverting input end of the operational amplifier unit, and the other end of the capacitor C12 is grounded.

4. The resolver excitation circuit according to claim 3, characterized in that: The positive phase input unit includes a resistor R18, a resistor R20, a capacitor C7 and a capacitor C8; One end of the resistor R18 is connected to the main control module, the other end of the resistor R18 is respectively connected to one end of the capacitor C7 and one end of the resistor R20, the other end of the capacitor C7 is connected to the first external power supply, the other end of the resistor R20 is respectively connected to one end of the capacitor C8 and the non-inverting input end of the operational amplifier unit, and the other end of the capacitor C8 is grounded.

5. The resolver excitation circuit according to claim 4, characterized in that: The operational amplifier unit includes a first operational amplifier, a resistor R9 and a capacitor C9; the slew rate of the first operational amplifier is not less than 0.613V / μs; The inverting input terminal of the first operational amplifier is respectively connected to the other end of the resistor R15, one end of the resistor R9 and one end of the capacitor C9, the non-inverting input terminal of the first operational amplifier is connected to the other end of the resistor R20, the output terminal of the first operational amplifier is respectively connected to the other end of the capacitor C9 and the push-pull module, and the other end of the resistor R9 is respectively connected to the push-pull module and the DC isolation module.

6. The resolver excitation circuit as claimed in claim 2, characterized in that: The push-pull module includes a first push-pull unit and a second push-pull unit; the first push-pull unit includes a resistor R10, a resistor R11, a resistor R13, a diode D6 and a transistor Q2; the second push-pull unit includes a resistor R19, a resistor R21, a resistor R17, a diode D9 and a transistor Q3; The cathode of the diode D6 is respectively connected to the anode of the diode D9 and the output end of the operational amplifier unit, the anode of the diode D6 is respectively connected to the base of the transistor Q2 and one end of the resistor R10 through the resistor R11, the other end of the resistor R10 is respectively connected to the collector of the transistor Q2 and a second external power supply, the emitter of the transistor Q2 is respectively connected to one end of the resistor R17, the feedback end of the operational amplifier unit and the DC isolation module through the resistor R13, the cathode of the diode D9 is respectively connected to the base of the transistor Q3 and one end of the resistor R21 through the resistor R19, the emitter of the transistor Q3 is connected to the other end of the resistor R17, and the other end of the resistor R21 and the collector of the transistor Q3 are grounded.

7. The resolver excitation circuit according to claim 6, characterized in that: The push-pull module further includes a first current limiting unit and a second current limiting unit; the first current limiting unit and the second current limiting unit each include at least one current limiting diode connected in series; One end of the first current limiting unit is connected to the base of the transistor Q2, the other end of the first current limiting unit is respectively connected to one end of the second current limiting unit, the common point of the resistor R13 and the resistor R17, and the other end of the second current limiting unit is connected to the base of the transistor Q3.

8. A rotary transformer electric drive system, characterized in that: The rotary transformer electric drive system comprises: The resolver excitation circuit according to any one of claims 1 to 7; A common mode excitation circuit, connected to the resolver excitation circuit, and configured to generate a first excitation differential drive signal and a second excitation differential drive signal according to a unilateral excitation drive signal output by the resolver excitation circuit; A rotary transformer is connected to the common mode excitation circuit and is used to operate according to the first excitation differential drive signal and the second excitation differential drive signal.

9. The resolver electric drive system according to claim 8, characterized in that: The rotary transformer electric drive system further includes an excitation recovery circuit, and the excitation recovery circuit includes: A first feedback module is connected to the first output end of the common mode excitation circuit, the second output end of the common mode excitation circuit and the main control module of the resolver excitation circuit respectively, and the first feedback module is used to adjust the amplitude of the first excitation differential drive signal and the second excitation differential drive signal for the main control module to perform amplitude verification; The second feedback module is respectively connected to the first output end of the common-mode excitation circuit, the second output end of the common-mode excitation circuit and the main control module of the resolver excitation circuit. The second feedback module is used to perform zero-crossing comparison on the first excitation differential drive signal and the second excitation differential drive signal for the main control module to perform frequency verification.

10. The resolver electric drive system according to claim 9, characterized in that: The first recovery feedback module includes a second operational amplifier, a resistor R34, a resistor R35, a resistor R36, a resistor R37 and a capacitor C25; One end of the resistor R35 is connected to the second output end of the common-mode excitation circuit, the other end of the resistor R35 is respectively connected to one end of the capacitor C25, one end of the resistor R34 and the inverting input end of the second operational amplifier, one end of the resistor R36 is connected to the first output end of the common-mode excitation circuit, the other end of the resistor R36 is respectively connected to one end of the resistor R37 and the non-inverting input end of the second operational amplifier, the other end of the resistor R37 is connected to a reference power supply, and the output end of the second operational amplifier is respectively connected to the other end of the capacitor C25, the other end of the resistor R34 and the main control module; The second recovery feedback module includes a third operational amplifier, a resistor R38, a resistor R39, a resistor R40, a resistor R41 and a resistor R42; One end of the resistor R41 is connected to the first output end of the common-mode excitation circuit, the other end of the resistor R41 is respectively connected to one end of the resistor R40 and the non-inverting input end of the third operational amplifier, the other end of the resistor R40 is connected to a second external power supply, one end of the resistor R42 is connected to the second output end of the common-mode excitation circuit, the other end of the resistor R42 is respectively connected to one end of the resistor R39 and the inverting input end of the third operational amplifier, the other end of the resistor R39 is connected to the other end of the resistor R40, the output end of the third operational amplifier is respectively connected to one end of the resistor R38 and the main control module, and the other end of the resistor R38 is connected to the first external power supply.

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