Three-phase load test circuit for testing motor driver

Abstract

The invention discloses a three-phase load test circuit for testing a motor driver, and the circuit comprises a three-phase bridge driver which is used for generating a three-phase AC voltage signal; the synchronous rectification module is used for synchronously rectifying the three-phase alternating-current voltage signal into a direct-current voltage signal and providing the direct-current voltage signal to an electronic load; the electronic load is used for simulating a resistive load and completing the test under the driving of the direct-current voltage signal; wherein the electronic load is set to be in a current source mode in which the magnitude of output current is adjustable; the MCU controller is used for calculating a PWM (Pulse Width Modulation) signal with a target duty ratio according to the electronic load feedback signal; the isolation driver is used for driving the three-phase bridge driver and the synchronous rectification module to work according to the PWM signal; the synchronous rectification module comprises a power inductor used for simulating an inductive load. A conventional resistive load test scheme is replaced by a scheme of combining an inductive load and an electronic load, and the method can be suitable for load verification test and aging screening test of the motor driver with any load current.

Description

Technical Field

[0001] This invention belongs to the field of motor driver testing technology, specifically relating to a three-phase load test circuit for testing motor drivers. Background Technology

[0002] Motor drivers are switching power devices that convert DC voltage into AC voltage through a specific switching sequence to control the rotation of a motor. Depending on the type of motor (generally divided into brushed and brushless motors), motor drivers are available in two-phase (H-bridge) and three-phase (full-bridge) configurations. The power range of motor drivers is wide, from 1W to 1000kW, and they frequently experience voltage and current spikes during operation. Therefore, current carrying capacity is a crucial indicator for motor drivers, often requiring phase output current carrying capacity compliance testing, as well as simultaneous power aging screening testing. Typically, when conducting capacity verification testing and power aging screening testing, methods such as... Figure 1 The conventional approach shown employs either a three-phase or two-phase resistive load. This conventional approach has two main shortcomings and limitations: Firstly, because the motor is an inductive load, a resistive load cannot accurately simulate the motor load and cannot provide a freewheeling mode. Secondly, the resistive load approach can only adjust the load current by changing the resistance value of the resistive load and the power supply voltage. Due to the limitations and continuity of the selection of the resistive load resistance and its rated power, the load current cannot be arbitrarily set, making it difficult to perform high-current load testing. Therefore, actual verification testing requires configuring various resistive loads with different resistance values ​​and power ratings, and each motor driver's aging load test board needs to be specially designed, which is not convenient for universal compatibility testing and is not suitable for load testing of high-power motor drive products. Summary of the Invention

[0003] To address the aforementioned testing issues, this application proposes a three-phase load test circuit for testing motor drives. This circuit replaces the conventional resistive load test scheme with a combination of inductive and electronic loads, making it suitable for load verification testing and aging screening testing of motor drives with any load current.

[0004] The technical solution adopted in this invention is as follows:

[0005] This application discloses a three-phase load test circuit for testing motor drivers, including:

[0006] A three-phase bridge driver is used to generate three-phase AC voltage signals;

[0007] a synchronous rectification module for synchronously rectifying the three-phase alternating voltage signal into a direct current voltage signal and providing the direct current voltage signal to the electronic load;

[0008] an electronic load for simulating a resistive load and completing the test under the driving of the direct current voltage signal; wherein the electronic load is configured to output a current source mode with adjustable current size;

[0009] an MCU controller for calculating a PWM signal with a target duty cycle according to the current signal fed back by the electronic load;

[0010] an isolation driver for driving the three-phase bridge driver and the synchronous rectification module to work according to the PWM signal; wherein the synchronous rectification module comprises a power inductor for simulating an inductive load.

[0011] As an optional technical solution, the three-phase bridge driver comprises MOS tubes Q1, Q2, Q3, Q4, Q5, and Q6; wherein the drains of MOS tubes Q1, Q3, and Q5 are connected to VCC, the sources of MOS tubes Q2, Q4, and Q6 are connected to zero potential; the source of MOS tube Q1 is connected to the drain of MOS tube Q4, and the connection point serves as a U-phase voltage output end; the source of MOS tube Q3 is connected to the drain of MOS tube Q6, and the connection point serves as a V-phase voltage output end; the source of MOS tube Q5 is connected to the drain of MOS tube Q2, and the connection point serves as a W-phase voltage output end.

[0012] As an optional technical solution, the synchronous rectification module comprises MOS tubes Q7, Q8, Q9, Q10, Q11, and Q12; wherein the source of MOS tube Q7 is connected to the drain of MOS tube Q10, and the connection point serves as a U-phase voltage input end; the source of MOS tube Q9 is connected to the drain of MOS tube Q12, and the connection point serves as a V-phase voltage input end; the source of MOS tube Q11 is connected to the drain of MOS tube Q8, and the connection point serves as a W-phase voltage input end; the drains of MOS tubes Q7, Q9, and Q11 are connected together as a first output end of the synchronous rectification module, and the sources of MOS tubes Q8, Q10, and Q12 are connected together as a second output end of the synchronous rectification module.

[0013] As an optional technical solution, the power inductor comprises: a power inductor L1 connected between the U-phase voltage output end of the three-phase bridge driver and the U-phase voltage input end of the synchronous rectification module; a power inductor L2 connected between the V-phase voltage output end of the three-phase bridge driver and the V-phase voltage input end of the synchronous rectification module; and a power inductor L3 connected between the W-phase voltage output end of the three-phase bridge driver and the W-phase voltage input end of the synchronous rectification module.

[0014] As an optional technical solution, the test circuit further comprises a type filter, and the type filter comprises capacitors C1 and C2 and an inductor L4; wherein two ends of the capacitor C1 are connected to the first output end and the second output end of the synchronous rectification module respectively, and two ends of the capacitor C2 are connected to two ends of the electronic load respectively.

[0015] As an optional technical solution, the isolation driver comprises:

[0016] A DC / DC conversion circuit is configured to convert the input VCC into a positive power voltage VDD and a negative power voltage VEE;

[0017] A gate drive circuit is configured to convert the positive power voltage VDD into a gate drive signal OUTH and convert the negative power voltage VEE into a gate drive signal OUTL according to the PWM signal, and the gate drive signals OUTH and OUTL are configured to drive the three-phase bridge driver and the synchronous rectification module.

[0018] As an optional technical solution, the DC / DC conversion circuit comprises a DC / DC driver, a transformer, diodes D1, D2 and D3, and capacitors C3 and C4; wherein the transformer comprises primary windings N1 and N2 and secondary windings N3, N4 and N5, two output ends VD1 and VD2 of the DC / DC driver are connected to the same end of the primary winding N1 and the different end of the primary winding N2 respectively, and an input end VIN of the DC / DC driver is connected to a primary center tap between the primary windings N1 and N2; the same end of the secondary winding N3 and the different end of the secondary winding N4 are connected to the anodes of the diodes D1 and D2 respectively, the cathodes of the diodes D1 and D2 are connected to one end of the capacitor C3, and the connection point is taken as a VDD output end, the other end of the capacitor C3 is connected to a secondary center tap between the secondary windings N3 and N4; the same end of the secondary winding N5 is connected to the anode of the diode D3, the cathode of the diode D3 is connected to one end of the capacitor C4, and the other end of the capacitor C4 is connected to the different end of the secondary winding N5, and the connection point is taken as a VEE output end.

[0019] As an optional technical solution, the gate drive circuit comprises a gate driver NSI6611, the VDD output end of the DC / DC conversion circuit is connected to an input end VCC2 of the gate driver, and the VEE output end of the DC / DC conversion circuit is connected to an input end VEE2 of the gate driver.

[0020] As an optional technical solution, the test circuit further comprises a secondary power supply, and the secondary power supply converts an input voltage Convert to meet the MCU controller and isolated driver output voltage used by the output voltage .

[0021] The application has the following advantages: in the application, the three-phase AC load of the motor driver is converted into a DC load, the DC load is provided by an electronic load, and the AC load is adjusted by adjusting the DC load. On the one hand, the load current can be arbitrarily set, and inductive load current is provided through the power inductors L1-L3, which can simulate the motor load to a certain extent, ensuring the convenience, compliance and safety of the test; on the other hand, the universal compatibility application test of different motor drivers is realized, without the need for special hardware configuration design, which provides an effective and reliable solution for the load verification test and aging screening test of the motor driver. BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1 is the existing resistive load test scheme of the motor driver.

[0023] Figure 2 is a circuit block diagram of the three-phase load test circuit for testing the motor driver in an exemplary embodiment.

[0024] Figure 3 is Figure 2 is a partial circuit structure diagram of the test circuit in

[0025] Figure 4 is a circuit block diagram of the isolated driver in an exemplary embodiment.

[0026] Figure 5 is a circuit schematic diagram of the DC / DC conversion circuit in an exemplary embodiment.

[0027] Figure 6 is a circuit schematic diagram of the gate drive circuit in an exemplary embodiment.

[0028] Figure 7 is a circuit schematic diagram of the secondary power supply in an exemplary embodiment.

[0029] Figure 8 is a conduction timing sequence of the power tube of the three-phase motor driver and a phase voltage waveform diagram thereof.

[0030] Figure 9 is a phase current waveform diagram of the three-phase motor driver. DETAILED DESCRIPTION

[0031] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0032] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0033] Example 1

[0034] like Figure 2 As shown, this application discloses a three-phase load test circuit for testing motor drivers. The test circuit includes: a three-phase bridge driver 10, a synchronous rectification module 20, an electronic load 30, an MCU controller 40, an isolation driver 50, and a secondary power supply 60. The three-phase bridge driver 10 generates a three-phase AC voltage signal; the synchronous rectification module 20 synchronously rectifies the three-phase AC voltage signal into a DC voltage signal and provides it to the electronic load 30, wherein the synchronous rectification module 20 includes a power inductor for simulating an inductive load; the electronic load 30 completes the test under the drive of the DC voltage signal, wherein the electronic load is set to a current source mode with adjustable output current; the MCU controller 40 calculates a PWM signal with a target duty cycle based on the current signal fed back from the electronic load; the isolation driver 50 drives the three-phase bridge driver 10 and the synchronous rectification module 20 to operate according to the PWM signal; and the secondary power supply 60 converts the input voltage... Converted to the output voltage used by the MCU controller 40 and the isolation driver 50 .

[0035] As an optional implementation method, such as Figure 3As shown in the figure, the three-phase bridge driver 10 includes MOS tubes Q1, Q2, Q3, Q4, Q5, Q6; wherein the drain of MOS tubes Q1, Q3, Q5 are all connected to VCC, the source of MOS tubes Q2, Q4, Q6 are all connected to zero potential; the source of MOS tube Q1 is connected to the drain of MOS tube Q4, and the connection point is used as the U-phase voltage output end; the source of MOS tube Q3 is connected to the drain of MOS tube Q6, and the connection point is used as the V-phase voltage output end; the source of MOS tube Q5 is connected to the drain of MOS tube Q2, and the connection point is used as the W-phase voltage output end.

[0036] As an optional implementation, as shown in the figure, Figure 3 As shown in the figure, the synchronous rectification module 20 includes MOS tubes Q7, Q8, Q9, Q10, Q11, Q12; wherein the source of MOS tube Q7 is connected to the drain of MOS tube Q10, and the connection point is used as the U-phase voltage input end; the source of MOS tube Q9 is connected to the drain of MOS tube Q12, and the connection point is used as the V-phase voltage input end; the source of MOS tube Q11 is connected to the drain of MOS tube Q8, and the connection point is used as the W-phase voltage input end; the drains of MOS tubes Q7, Q9, Q11 are connected together as the first output end of the synchronous rectification module, and the sources of MOS tubes Q8, Q10, Q12 are connected together as the second output end of the synchronous rectification module.

[0037] As an optional implementation, as shown in the figure, Figure 3 As shown in the figure, power inductors L1-L3 constitute a three-phase inductive load, which functions to generate inductive load current characteristics. The power inductor L1 is connected between the U-phase voltage output end of the three-phase bridge driver 10 and the U-phase voltage input end of the synchronous rectification module 20; the power inductor L2 is connected between the V-phase voltage output end of the three-phase bridge driver 10 and the V-phase voltage input end of the synchronous rectification module 20; the power inductor L3 is connected between the W-phase voltage output end of the three-phase bridge driver 10 and the W-phase voltage input end of the synchronous rectification module 20.

[0038] As an optional implementation, as shown in the figure, Figure 3 As shown in the figure, the test circuit further includes a type filter connected between the synchronous rectification module 20 and the electronic load 30, and the type filter includes capacitors C1, C2 and an inductor L4; wherein the two ends of the capacitor C1 are respectively connected to the first output end and the second output end of the synchronous rectification module 20, and the two ends of the capacitor C2 are respectively connected to the two ends of the electronic load 30.

[0039] As an optional implementation, as shown in the figure, Figure 4 As shown in the figure, the isolation driver 50 includes:

[0040] DC / DC conversion circuit 501, for converting the input VCC into positive supply voltage VDD and negative supply voltage VEE;

[0041] Gate drive circuit 502, for converting the positive supply voltage VDD into gate drive signal OUTH and converting the negative supply voltage VEE into gate drive signal OUTL according to the PWM signal, the gate drive signals OUTH and OUTL are used to drive the three-phase bridge driver 10 and the synchronous rectification module 20.

[0042] As an optional embodiment, as shown in Figure 5 The DC / DC conversion circuit 501 includes: DC / DC driver U1, transformer U2, diodes D1, D2, D3 and capacitors C3, C4; wherein the transformer U2 includes primary winding N1, N2 and secondary winding N3, N4, N5, the two output terminals VD1, VD2 of the DC / DC driver U1 are connected to the same name terminal of the primary winding N1 and the different name terminal of the primary winding N2 respectively, the input terminal VIN of the DC / DC driver U1 is connected to the primary center tap between the primary windings N1, N2; the same name terminal of the secondary winding N3 and the different name terminal of the secondary winding N4 are connected to the anodes of the diodes D1, D2 respectively, the cathodes of the diodes D1, D2 are connected to each other and connected to one end of the capacitor C3, the connection point is the VDD output terminal, the other end of the capacitor C3 is connected to the secondary center tap between the secondary windings N3, N4; the same name terminal of the secondary winding N5 is connected to the anode of the diode D3, the cathode of the diode D3 is connected to one end of the capacitor C4, the other end of the capacitor C4 is connected to the different name terminal of the secondary winding N5, the connection point is the VEE output terminal.

[0043] As an optional embodiment, as shown in Figure 6 The gate drive circuit 502 includes gate driver NSI6611, the VDD output terminal of the DC / DC conversion circuit 501 is connected to the input terminal VCC2 of the gate driver, and the VEE output terminal of the DC / DC conversion circuit 501 is connected to the input terminal VEE2 of the gate driver.

[0044] As an optional embodiment, the specific circuit structure of the secondary power supply 60 is as shown in Figure 7 It converts the input voltage into 5V output voltage , and the 5V output is used for the MCU controller 40 and the isolation driver 50.

[0045] As an optional implementation, the electronic load 30 can adopt IT8906A-150-600 type electronic load; the power inductance (L1-L4) can adopt power inductance with inductance of 1 mH and rated current of 200 A; the filter capacitor (C1, C2) can adopt polar capacitor with capacitance of 470 μF and voltage resistance of 450 V; the power MOS tube (Q7-Q12) can adopt the same power MOS of three-phase bridge driver in rated voltage resistance and current; the DC / DC driver U1 can adopt SN6501, the MCU controller 40 can adopt STM32F4, and the controller in the secondary power supply 60 can adopt LTC3805. The embodiment only gives an implementable selection, and does not limit to use these models.

[0046] In order to better understand the embodiment, the test circuit of the embodiment is further analyzed and described below.

[0047] As shown in Figure 1 , when the three-phase motor driver adopts two-to-two conduction control mode (that is, at any time, only two power tubes are turned on), the conduction sequence of the internal power tubes Q1-Q6 is: Q3 and Q4 are turned on (the others are turned off) → Q4 and Q5 are turned on (the others are turned off) → Q5 and Q6 are turned on (the others are turned off) → Q6 and Q1 are turned on (the others are turned off) → Q1 and Q2 are turned on (the others are turned off) → Q2 and Q3 are turned on (the others are turned off) → Q3 and Q4 are turned on (the others are turned off) → …, and so on. The corresponding conduction timing and phase voltage waveform are shown in Figure 8 (ideal state, ignoring the peak voltage). As can be seen, the three-phase voltage waveform is an alternating three-segment voltage waveform, and the three-segment voltage values are 0 V, 1 / 2 VP and VP (VP is the DC power supply voltage), and the corresponding three-phase current waveform is also an alternating three-segment, and the three-segment current values are -IL, 0 A and +IL (IL is the load current), as shown in Figure 9 (ideal state, ignoring the peak current), therefore, the three-phase motor driver is a product that converts DC to AC.

[0048] As shown in Figure 1The conventional circuit shown can only adjust the size of the load current IL by changing the power supply voltage VP and the resistance load resistance RL, and cannot arbitrarily set the load current, so it cannot be applied universally. To solve the problem of continuous and arbitrary setting of the load current and safety testing, the current source mode of the electronic load can be used to replace the resistive load, but the electronic load can only be applied to single-phase loads in direct current mode and cannot be directly applied to motor drive three-phase load circuits with high-speed switching. To solve the applicability problem of the electronic load, the scheme of converting an alternating current load into a direct current load is adopted. After the three-phase alternating current load of the motor drive is shaped by synchronous rectification, it is converted into a single-phase direct current load, which is then delivered to the electronic load. To simulate the inductive load characteristics of the motor, the load testing of the motor driver has a freewheeling mode (the inductive load current cannot be suddenly changed, and when the power tube switches, the freewheeling diode inside the power tube needs to be used for freewheeling), and the actual application conditions are simulated more realistically. The embodiment adopts the technical scheme of integrating a three-phase inductive load on the basis of the above-mentioned electronic load scheme, and the overall circuit block diagram is as shown in Figure 2 so as to be applicable to the load testing of three-phase motor drivers of different motor types and different control modes.

[0049] As shown in Figure 2 The test current of the embodiment mainly includes a three-phase bridge driver 10, a synchronous rectifier 20, an electronic load 30, an MCU controller 40, an isolation driver 50, and a secondary power supply 60. The power part of the three-phase bridge driver, the synchronous rectifier, and the electronic load is as shown in Figure 3 Among them, L1-L3 are power inductors, which constitute a three-phase inductive load and have the function of generating inductive load current characteristics and simulating the motor load to a certain extent; Q7-Q12 are power MOS tubes, which constitute a three-phase synchronous rectifier and have the function of rectifying the three-phase alternating phase voltage output by the motor driver 10 through a unidirectional conduction rectifier bridge. The conduction sequence of the motor driver inside is Q3Q4→Q4Q5→Q5Q6→Q6Q1→Q1Q2→Q2Q3→Q3Q4→……, which corresponds to the conduction sequence of the rectifier bridge Q9Q10→Q10Q11→Q11Q12→Q12Q7→Q7Q8→Q8Q9→Q9Q10→……. After rectification, a current flow in one direction is always generated, which corresponds to a direct current voltage, and finally provides a direct current supply voltage for the electronic load 30 to meet the working requirements of the electronic load 30.

[0050] At the same time, since the circuit ground loop of the synchronous rectification part is floating, in order to ensure the reliable turn-off of the synchronous rectification part circuit, the self-boosting drive mode cannot be used, and the isolation drive control of the integrated isolation power supply needs to be used, as shown in Figure 4As shown, the isolation driver 50 is a SiC / IGBT gate driver integrated with an isolation DC / DC power supply. It is powered by a single power supply +5V, and internally generates an isolated VDD (+13V~20V) positive supply voltage and VEE (-4.5V~ -2.5V) negative supply voltage. It can convert a PWM signal with a duty cycle of 0~100% into an isolated gate drive signal (OUTH and OUTL) of VDD and VEE, providing a maximum transient peak drive current of 8A. At the same time, the module has functions such as current limiting protection, output Muller clamp, fault soft shutdown, undervoltage protection, and status indication (undervoltage / overcurrent).

[0051] In addition, since both the isolation driver 50 and the MCU controller 40 are powered by 5V, a secondary power conversion circuit is needed to convert the input voltage into a working voltage suitable for the isolation driver 50 and the MCU controller 40. The circuit structure of the secondary power supply 60 is as shown. Figure 7 To ensure good heat dissipation, the charging main circuit uses a PWM chip + external MOS tube (Q13, Q14) form. This circuit architecture can provide sufficient current loop for the main circuit, and the external MOS can also provide sufficient heat dissipation path.

[0052] As shown in Figure 3 , C1, C2, and L4 form a π-type filter. Due to the stable hysteresis in the switching process of the rectifier bridge, the rectified voltage has different degrees of pulsation. In order to suppress this voltage pulsation, a π-type filter is used to store energy and filter the rectified voltage, providing a stable and smooth DC voltage for the electronic load 30. When adjusting the electronic load, the current signal needs to be fed back synchronously. The MCU calculates a PWM signal with a matching duty cycle (i.e. the above-mentioned target duty cycle) and transmits it to the isolation driver 50, which is used to drive the three-phase bridge driver 10 and the synchronous rectification module 20. This avoids the risk of MOS chip overheating caused by mismatch between load size and PWM duty cycle. In this embodiment, the electronic load output current size can be set according to actual load current test requirements (current source mode). On the one hand, the load current size can be set arbitrarily, and the load current is independent of the power supply voltage, which can be applied to load verification tests of motor drivers with different voltages and power levels. On the other hand, when different products are subjected to aging screening tests, there is no need to configure a dedicated hardware aging load. The same load test circuit of this embodiment can be used for large current load safety testing, effectively solving the problems of conventional load test circuits, and providing a feasible and advanced load test solution for motor drivers.

[0053] To better apply the test circuit of this embodiment, the design of its test method will also be introduced. When the motor driver is applied to a brushless DC motor, it often adopts a two-way conduction control method, and the logic control signals input to the front stage need to meet the following requirements. Figure 8 The conduction sequence of Q1 to Q6 is shown. The electronic load 30 is set to current source output mode. The output current IL of the electronic load 30 is set according to the required load current. The power supply voltage is set according to the product's operating voltage requirements. The motor driver 10 can then generate a three-phase square wave inductive load current (three-segment square wave current with current values ​​of -IL, 0A, and +IL). The frequency of the three-phase load current is consistent with the input control signal. Adjusting the input signal frequency can adjust the duration of the load current. Therefore, the load capacity test of this type of motor driver is realized. The same test method is also used in the corresponding power aging screening test. When a motor driver is applied to a permanent magnet synchronous motor, it often employs a three-on-three control method (i.e., three power transistors are simultaneously turned on at any given moment). The logic control signals input to the front stage need to be 6-channel SVPWM signals, making the conduction timing waveforms of Q1 to Q6 close to a sine wave. Therefore, this control method is also called sine wave control. The electronic load 30 is set to current source output mode, and the output current IL of the electronic load is set according to the required load current. The power supply voltage is set according to the product's operating voltage requirements. The motor driver can then generate a three-phase sinusoidal inductive load current (the peak values ​​of the sinusoidal currents are -...). IL, + The three-phase load current frequency is consistent with the input control signal, so the load capacity test is carried out when driving this type of motor. The same test method is also used when conducting the corresponding power aging screening test.

[0054] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in this application should be included within the scope of protection of this application. All technical solutions that fall within the scope of the claims of this invention are within the scope of protection of this invention.

Claims

1. A three-phase load test circuit for testing motor drivers, characterized in that, include: A three-phase bridge driver is used to generate three-phase AC voltage signals; the three-phase bridge driver contains power transistors, and each power transistor contains a body diode. A synchronous rectification module is used to synchronously rectify the three-phase AC voltage signal into a DC voltage signal and provide it to the electronic load; wherein, the synchronous rectification module includes a power inductor for simulating an inductive load; when the three-phase bridge power transistor switches, freewheeling current is required through the body diode inside the power transistor; An electronic load, used to simulate a resistive load, completes the test under the drive of the DC voltage signal; wherein, the electronic load is set to a current source mode with adjustable output current. The MCU controller is used to calculate a PWM signal with a target duty cycle based on the current signal fed back from the electronic load. An isolation driver is used to drive the three-phase bridge driver and synchronous rectification module to work according to the PWM signal.

2. The three-phase load test circuit for testing a motor driver according to claim 1, characterized in that: The three-phase bridge driver includes MOSFETs Q1, Q2, Q3, Q4, Q5, and Q6, each MOSFET containing a body diode. The drains of MOSFETs Q1, Q3, and Q5 are all connected to VCC, and the sources of MOSFETs Q2, Q4, and Q6 are all connected to zero potential. The source of MOSFET Q1 is connected to the drain of MOSFET Q4, and this connection point serves as the U-phase voltage output terminal. The source of MOSFET Q3 is connected to the drain of MOSFET Q6, and this connection point serves as the V-phase voltage output terminal. The source of MOSFET Q5 is connected to the drain of MOSFET Q2, and this connection point serves as the W-phase voltage output terminal.

3. The three-phase load test circuit for testing a motor driver according to claim 2, characterized in that: The synchronous rectification module includes MOSFETs Q7, Q8, Q9, Q10, Q11, and Q12. The source of MOSFET Q7 is connected to the drain of MOSFET Q10, and this connection point serves as the U-phase voltage input terminal. The source of MOSFET Q9 is connected to the drain of MOSFET Q12, and this connection point serves as the V-phase voltage input terminal. The source of MOSFET Q11 is connected to the drain of MOSFET Q8, and this connection point serves as the W-phase voltage input terminal. The drains of MOSFETs Q7, Q9, and Q11 are connected together as the first output terminal of the synchronous rectification module, and the sources of MOSFETs Q8, Q10, and Q12 are connected together as the second output terminal of the synchronous rectification module.

4. The three-phase load test circuit for testing a motor driver according to claim 3, characterized in that, The power inductors include: a power inductor L1 connected between the U-phase voltage output terminal of the three-phase bridge driver and the U-phase voltage input terminal of the synchronous rectification module; a power inductor L2 connected between the V-phase voltage output terminal of the three-phase bridge driver and the V-phase voltage input terminal of the synchronous rectification module; and a power inductor L3 connected between the W-phase voltage output terminal of the three-phase bridge driver and the W-phase voltage input terminal of the synchronous rectification module.

5. The three-phase load test circuit for testing a motor driver according to claim 3, characterized in that: The test circuit also includes a connection between the synchronous rectification module and the electronic load. Type filter, the The filter includes capacitors C1 and C2 and inductor L4; wherein, the two ends of capacitor C1 are connected to the first output terminal and the second output terminal of the synchronous rectification module, respectively, and the two ends of capacitor C2 are connected to the two ends of the electronic load, respectively.

6. The three-phase load test circuit for testing a motor driver according to any one of claims 1-5, characterized in that, The isolation driver includes: A DC / DC converter circuit is used to convert the input VCC into a positive power supply voltage VDD and a negative power supply voltage VEE. The gate drive circuit is used to convert the positive power supply voltage VDD into a gate drive signal OUTH and the negative power supply voltage VEE into a gate drive signal OUTL according to the PWM signal. Both the gate drive signals OUTH and OUTL are used to drive the three-phase bridge driver and the synchronous rectification module.

7. The three-phase load test circuit for testing a motor driver according to claim 6, characterized in that, The DC / DC conversion circuit includes: a DC / DC driver, a transformer, diodes D1, D2, and D3, and capacitors C3 and C4; wherein, the transformer includes primary windings N1 and N2 and secondary windings N3, N4, and N5; the two output terminals VD1 and VD2 of the DC / DC driver are respectively connected to the same-name terminal of the primary winding N1 and the opposite-name terminal of the primary winding N2; the input terminal VIN of the DC / DC driver is connected to the center tap of the primary windings N1 and N2; the secondary winding N3... The same-name terminal of the secondary winding N5 and the opposite-name terminal of the secondary winding N4 are connected to the anodes of diodes D1 and D2, respectively. The cathodes of diodes D1 and D2 are connected together and then connected to one end of capacitor C3. This connection point serves as the VDD output terminal. The other end of capacitor C3 is connected to the center tap of the secondary winding between secondary windings N3 and N4. The same-name terminal of the secondary winding N5 is connected to the anode of diode D3. The cathode of diode D3 is connected to one end of capacitor C4. The other end of capacitor C4 is connected to the opposite-name terminal of the secondary winding N5. This connection point serves as the VEE output terminal.

8. The three-phase load test circuit for testing a motor driver according to claim 7, characterized in that: The gate drive circuit includes a gate driver NSI6611. The VDD output terminal of the DC / DC conversion circuit is connected to the input terminal VCC2 of the gate driver, and the VEE output terminal of the DC / DC conversion circuit is connected to the input terminal VEE2 of the gate driver.

9. The three-phase load test circuit for testing a motor driver according to any one of claims 1-5, characterized in that: The test circuit also includes a secondary power supply, which will input voltage. Converted to the output voltage used by the MCU controller and isolation driver .

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