A three-phase load test circuit for testing a motor driver

Abstract

The application discloses a three-phase load test circuit for testing a motor driver, comprising: a three-phase bridge driver for generating a three-phase alternating voltage signal; 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 an electronic load; the electronic load is used for simulating a resistive load and completing test under the driving of the direct current voltage signal; wherein the electronic load is set as a current source mode with adjustable output current size; an MCU controller is used for calculating a PWM signal with a target duty cycle according to an electronic load feedback signal; an isolation driver is used 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. The scheme of combining the inductive load with the electronic load is used to replace a conventional resistive load test scheme, and can be applied to load verification test and aging screening test of the motor driver with any load current size.

Description

A three-phase load test circuit for testing motor drivers 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, the conventional approach shown in Figure 1, employing a three-phase or two-phase resistive load, is used for both capacity verification and power aging screening tests. This conventional solution has two main shortcomings and defects: First, because the motor is an inductive load, a resistive load cannot truly simulate and replace the motor load, and it cannot provide a freewheeling mode. Second, the resistive load solution can only adjust the load current by changing the resistive load resistance and the power supply voltage. Due to the limitations and continuity of the selection of resistive load resistance and rated power, the load current cannot be arbitrarily set, making it difficult to achieve high-current load testing. Therefore, in actual verification testing, it is necessary to configure various resistive loads with different resistance values ​​and power ratings, and the aging load test board for each motor driver needs to be specially designed, which is not convenient for general compatibility application 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 is used to synchronously rectify the three-phase AC voltage signal into a DC voltage signal and provide it to the electronic load;

[0008] 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.

[0009] 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.

[0010] An isolation driver is used to drive the three-phase bridge driver and the synchronous rectification module to operate according to the PWM signal; wherein the synchronous rectification module includes a power inductor for simulating an inductive load.

[0011] As an optional technical solution, the three-phase bridge driver includes MOSFETs Q1, Q2, Q3, Q4, Q5, and Q6; wherein 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.

[0012] As an optional technical solution, the synchronous rectification module includes MOSFETs Q7, Q8, Q9, Q10, Q11, and Q12; wherein, 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.

[0013] As an optional technical solution, the power inductor includes: 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.

[0014] As an optional technical solution, the test circuit further 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.

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

[0016] 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.

[0017] 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.

[0018] As an optional technical solution, 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, and the input terminal VIN of the DC / DC driver is connected to the primary center tap between the primary windings N1 and N2; The same-name terminal of secondary winding N3 and the opposite-name terminal of 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 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 secondary winding N5. This connection point serves as the VEE output terminal.

[0019] As an optional technical solution, the gate driving 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.

[0020] As an optional technical solution, the test circuit also includes a secondary power supply, which receives the input voltage. Converted to the output voltage used by the MCU controller and isolation driver .

[0021] The beneficial effects of this invention are as follows: In this application, the three-phase AC load of the motor driver is converted into a DC load, which is provided by an electronic load. The AC load is adjusted by adjusting the DC load. On the one hand, the load current can be set arbitrarily, and the inductive load current is provided by 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, it realizes the universal compatibility application test of different motor drivers without the need for special hardware configuration design, providing an effective and reliable solution for load verification test and aging screening test of motor drivers. Attached Figure Description

[0022] Figure 1 shows the existing resistive load test scheme for motor drivers.

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

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

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

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

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

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

[0029] Figure 8 shows the turn-on timing of the power transistors in a three-phase motor driver and their phase voltage waveforms.

[0030] Figure 9 shows the phase current waveform of a three-phase motor driver. Detailed Implementation

[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] As shown in Figure 2, this application discloses a three-phase load test circuit for testing a motor driver. 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, as shown in Figure 3, the three-phase bridge driver 10 includes MOSFETs Q1, Q2, Q3, Q4, Q5, and Q6; wherein 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.

[0036] As an optional implementation, as shown in Figure 3, the synchronous rectification module 20 includes MOSFETs Q7, Q8, Q9, Q10, Q11, and Q12; wherein, 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.

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

[0038] As an optional implementation, as shown in FIG3, the test circuit further includes a connection between the synchronous rectification module 20 and the electronic load 30. 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 20, respectively, and the two ends of capacitor C2 are connected to the two ends of the electronic load 30, respectively.

[0039] As an optional implementation, as shown in FIG4, the isolation driver 50 includes:

[0040] DC / DC converter circuit 501 is used to convert the input VCC into positive power supply voltage VDD and negative power supply voltage VEE;

[0041] The gate drive circuit 502 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 10 and the synchronous rectification module 20.

[0042] As an optional implementation, as shown in Figure 5, the DC / DC conversion circuit 501 includes: a DC / DC driver U1, a transformer U2, diodes D1, D2, and D3, and capacitors C3 and C4; wherein, the transformer U2 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 U1 are respectively connected to the same-name terminal of the primary winding N1 and the opposite-name terminal of the primary winding N2; and the input terminal VIN of the DC / DC driver U1 is connected between the primary windings N1 and N2. The primary winding has a center tap; the same-name terminal of the secondary winding N3 and the opposite-name terminal of the secondary winding N4 are respectively connected to the anodes of diodes D1 and D2. 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.

[0043] As an optional implementation, as shown in FIG6, the gate drive circuit 502 includes a 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 implementation, the specific circuit structure of the secondary power supply 60 is shown in Figure 7, which converts the input voltage... Converted to 5V output voltage The 5V output supplies power to the MCU controller 40 and the isolation driver 50.

[0045] As an optional implementation, the electronic load 30 can be an IT8906A-150-600 type electronic load; the power inductors (L1 to L4) can be power inductors with an inductance of 1mH and a rated current of 200A; the filter capacitors (C1, C2) can be polarized capacitors with a capacitance of 470μF and a withstand voltage of 450V; the power MOSFETs (Q7 to Q12) can be the same power MOSFETs as those in the three-phase bridge driver with rated withstand voltage and current; the DC / DC driver U1 can be an SN6501; the MCU controller 40 can be an STM32F4; and the controller in the secondary power supply 60 can be an LTC3805. This embodiment only provides one feasible selection and does not limit the use of these models.

[0046] To better understand this embodiment, the test circuit of this embodiment will be further analyzed and explained below.

[0047] As shown in Figure 1, when the three-phase motor driver adopts the two-by-two conduction control mode (i.e., only two power transistors are conducting at any given time), the conduction sequence of its internal power transistors Q1 to Q6 is as follows: Q3 and Q4 are both conducting (others are off) → Q4 and Q5 are both conducting (others are off) → Q5 and Q6 are both conducting (others are off) → Q6 and Q1 are both conducting (others are off) → Q1 and Q2 are both conducting (others are off) → Q2 and Q3 are both conducting (others are off) → Q3 and Q4 are both conducting (others are off) → ..., and so on, alternating in this cycle. The corresponding conduction sequence and its phase voltage waveform are shown in Figure 8 (ideally, peak voltages are ignored). As can be seen, the three-phase voltage waveform is an AC three-segment voltage waveform, with the three voltage values ​​being 0V, 1 / 2VP, and VP (VP is the DC power supply voltage). The corresponding three-phase current waveform is also an AC three-segment waveform, with the three current values ​​being -IL, 0A, and +IL (IL is the load current), as shown in Figure 9 (ideally, peak current is ignored). Therefore, a three-phase motor driver is a product that converts DC to AC.

[0048] Using the conventional circuit shown in Figure 1, the load current IL can only be adjusted by changing the power supply voltage VP and the resistive load resistance RL. The load current cannot be arbitrarily set, thus limiting its general applicability. To address the issues of arbitrarily setting the continuous load current and safety testing, an electronic load in current source mode can be used to replace the resistive load. However, electronic loads are often only suitable for single-phase DC loads and cannot be directly applied to high-speed switching motor-driven three-phase load circuits. To solve the applicability problem of electronic loads, an AC load to DC load conversion scheme is adopted. The three-phase AC load driven by the motor is converted into a single-phase DC load through synchronous rectification and shaping, and then supplied to the electronic load. To synchronously simulate the inductive load characteristics of the motor and enable the motor driver to have a freewheeling mode during load testing (the inductive load current cannot change abruptly, and when the three-phase bridge power transistor switches, it needs to be freewheeled through the freewheeling diode inside the power transistor) and to more realistically simulate actual application conditions, this embodiment adopts a technical solution that integrates a three-phase inductive load on the basis of the above electronic load scheme. The overall circuit block diagram is shown in Figure 2, so that it can be applied to the load testing of three-phase motor drivers with different motor types and different control methods.

[0049] As shown in Figure 2, the test current in this 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 components, such as the three-phase bridge driver, synchronous rectifier, and electronic load, are shown in Figure 3. L1 to L3 are power inductors, forming a three-phase inductive load. Their function is to generate inductive load current characteristics, which can simulate a motor load to a certain extent. Q7 to Q12 are power MOSFETs, forming a three-phase synchronous rectifier. Their function is to rectify the three-phase AC phase voltage output by the motor driver 10 through the rectifier bridge in a unidirectional manner. The conduction sequence inside the motor driver is: Q3Q4→Q4Q5→Q5Q6→Q6Q1→Q1Q2→Q2Q3→Q3Q4→……, which corresponds to the conduction sequence of the rectifier bridge as: Q9Q10→Q10Q11→Q11Q12→Q12Q7→Q7Q8→Q8Q9→Q9Q10→……. After rectification, a current always flows in one direction, which is converted into DC voltage, and finally provides DC power supply voltage to the electronic load 30 to meet the working requirements of the electronic load 30.

[0050] Meanwhile, since the ground loop of the synchronous rectification circuit is floating, a bootstrap drive mode cannot be used to ensure reliable shutdown of the synchronous rectification circuit. Instead, an isolated drive control with an integrated isolated power supply is required, as shown in Figure 4. The isolated driver 50 is a SiC / IGBT gate driver with an integrated isolated DC / DC power supply. It is powered by a single +5V supply and internally generates an isolated VDD (+13V~20V) positive power supply voltage and a VEE (-4.5V~-2.5V) negative power supply voltage. It can convert PWM signals with a duty cycle of 0~100% into isolated VDD and VEE gate drive signals (OUTH and OUTL), providing a maximum transient peak drive current of 8A. The module also features current limiting protection, output Miller clamping, 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 required to convert the input voltage to a voltage suitable for the operating voltage of the isolation driver 50 and the MCU controller 40. The circuit structure of the secondary power supply 60 is shown in Figure 7. To ensure good heat dissipation, the charging main circuit adopts a PWM chip + external MOSFETs (Q13, Q14). This circuit architecture can provide sufficient current for the main circuit, and the external MOSFETs can also provide sufficient heat dissipation paths.

[0052] As shown in Figure 3, C1, C2, and L4 form a π-type filter. Due to the certain degree of stability lag during the switching process of the rectifier bridge, the rectified voltage exhibits varying degrees of pulsation. To suppress this voltage pulsation, a π-type filter is used to store and filter the rectified voltage, providing a stable and smooth DC voltage to the subsequent electronic load 30. During electronic load adjustment, a current signal needs to be synchronously fed back. The MCU calculates and matches a PWM signal with a suitable duty cycle (i.e., the target duty cycle mentioned above) and transmits it to the isolation driver 50 to drive the three-phase bridge driver 10 and the synchronous rectification module 20. This avoids the risk of MOS chip overheating caused by a mismatch between the load size and the PWM duty cycle. This embodiment allows for setting the output current of the electronic load according to actual load current testing requirements (current source mode). On one hand, it enables arbitrary setting of the load current, and the load current is independent of the power supply voltage, making it suitable for load verification testing of motor drivers with different voltages and power levels. On the other hand, it eliminates the need for dedicated hardware aging loads during aging screening tests of different products; the same load test circuit of this embodiment can be used. Furthermore, it enables high-current load safety testing, effectively solving the problems of conventional load test circuits and providing a feasible and advanced load testing solution for motor drivers.

[0053] To better apply the test circuit of this embodiment, the design of its test method is also introduced. When the motor driver is applied to a brushless DC motor, it often adopts a two-way conduction control mode. The logic control signal input to the front stage needs to meet the conduction timing of Q1 to Q6 as shown in Figure 8. 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 respectively). 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 a three-phase AC voltage signal. The driver includes power transistors, each containing a freewheeling 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. The synchronous rectification module includes a power inductor to simulate an inductive load. When the three-phase bridge power transistor switches, freewheeling current is provided through the freewheeling diode inside the power transistor. An electronic load, simulating a resistive load, completes the test under the drive of the DC voltage signal. The electronic load is configured as a current source with adjustable output current. An MCU controller is used to adjust the output current according to the electronic load. The feedback current signal is used to calculate a PWM signal with a target duty cycle; an isolation driver is used to drive the three-phase bridge driver and synchronous rectification module according to the PWM signal; the isolation driver includes: a DC / DC conversion circuit for converting the input VCC into a positive power supply voltage VDD and a negative power supply voltage VEE; a gate drive circuit for converting 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, wherein both the gate drive signals OUTH and OUTL are used to drive the three-phase bridge driver and synchronous rectification module; The DC / DC conversion circuit includes: a DC / DC driver, a transformer, diodes D1, D2, and D3, and capacitors C3 and C4. 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 connected to the same-name terminal of primary winding N1 and the opposite-name terminal of primary winding N2, respectively. The input terminal VIN of the DC / DC driver is connected to the center tap of the primary windings N1 and N2. The same-name terminal of secondary winding N3 and the opposite-name terminal of secondary winding N4 are connected to the anodes of diodes D1 and D2, respectively. The cathodes of diodes D1 and D2 are connected to the capacitors. One end of capacitor C3 is connected to the secondary winding N3 and N4, with the connection point serving as the VDD output terminal. The other end of capacitor C3 is connected to the secondary center tap between the 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, and the other end of capacitor C4 is connected to the opposite-name terminal of the secondary winding N5, with the connection point serving as the VEE output terminal. 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.

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 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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