Gallium nitride motor controller and resonance cancellation method

Abstract

The present application relates to a kind of gallium nitride motor controllers and resonance elimination method, belong to power electronics field, solve when using traditional RC absorption circuit, resistance is easy to overheat damage under high-frequency switching condition, leading to the problem of protection function failure.Control device includes: power supply, with motor series connection, control motor's on-off electricity, including the gallium nitride switch tube with parasitic capacitance;Resonance elimination circuit, connected to power supply control device, freewheeling diode and the absorption capacitor and bleeder resistor connected in parallel are connected in series, when gallium nitride switch tube is in the off stage, current is through freewheeling diode forward conduction, absorption capacitor is charged so that absorption capacitor voltage gradually rises;When gallium nitride switch tube is in energy bleeder stage and capacitor rises to predetermined voltage, discharge is carried out through resistor, and electric energy is converted into heat energy and is smoothly dissipated.Effective inhibition of high-frequency resonance and reliable protection of switch tube are realized.

Description

Technical Field

[0001] This invention relates to the field of power electronics technology, and in particular to a gallium nitride motor controller and a resonance elimination method. Background Technology

[0002] As power electronic devices evolve towards higher frequencies and higher power densities, gallium nitride (GaN) high electron mobility transistors (HEMTs) are increasingly becoming ideal switching devices for high-frequency motor drive systems due to their superior characteristics such as high switching speed, low on-resistance, and high voltage withstand capability. However, during high-frequency switching, an LC resonant circuit is formed between the equivalent inductance of the motor windings and the parasitic capacitance of the switching transistor itself, leading to high-frequency oscillations and voltage spikes across the transistor. These voltage spikes not only increase the electrical stress on the switching transistor but can also cause device breakdown in severe cases, affecting system reliability and lifespan.

[0003] like Figure 1 As shown, during the motor drive process, when the PWM signal drives the gate G of the switching transistor to turn on, the current flows into the upper part of the motor and out the lower part, passing through the switching transistor DS to GND. At this time, the voltage across the motor terminals is + on the upper side and - on the lower side.

[0004] like Figure 2 As shown, when the switch is turned off, since the motor is an inductive load, the current in its equivalent inductance L cannot change abruptly, resulting in a reverse induced electromotive force. This forms a voltage with upper negative and lower positive values ​​applied across the switch transistor DS. At this time, the power supply voltage and the inductor voltage are connected in series, and the voltage across the switch transistor DS is the sum of the two. The energy stored in the inductor charges the parasitic capacitance Coss of the switch transistor, forming an LC resonant circuit. During resonance, the inductor energy and the capacitor energy are interconverted, and their relationship can be expressed as:

[0005]

[0006] Where L is the equivalent inductance of the motor; i is the inductor current; Coss is the parasitic capacitance of the switching transistor (typically only in the pF range); U is the voltage across the switching transistor; and Δt is the switching time. Because Coss is extremely small, U will rise sharply during high-frequency switching (i.e., extremely short Δt), easily leading to overvoltage breakdown of the switching transistor. However, this scheme lacks any buffer or absorption circuitry, and the switching transistor directly withstands the high-voltage spike caused by high-frequency resonance at turn-off, easily leading to overvoltage breakdown and poor system reliability.

[0007] like Figure 3 As shown, an RC snubber circuit consisting of diode D, capacitor Csn, and resistor Rsn is connected in parallel across the DS terminals of the switching transistor. When the switching transistor is turned off, the equivalent inductance current of the motor charges capacitor Csn through diode D, storing energy; subsequently, the capacitor discharges through resistor Rsn, dissipating the energy as heat. The instantaneous power dissipation of resistor Rsn can be expressed as:

[0008] in Let Csn be the voltage across the capacitor. Under high-frequency switching conditions, Δt is extremely small, and the capacitor charging voltage is high, resulting in a very large PR. The resistor is prone to overheating and burning out, thus losing its protective function, and the switching transistor still faces the risk of breakdown. However, under high-frequency switching conditions, the high capacitor charging voltage and large instantaneous power dissipation of the resistor make it susceptible to overheating and damage, leading to the failure of the absorption circuit and the switching transistor still facing the risk of breakdown. Furthermore, the selection of the resistor and its thermal design are challenging, limiting system reliability. Summary of the Invention

[0009] Based on the above analysis, the present invention aims to provide a gallium nitride motor controller and resonance elimination method to solve the problem that when using a traditional RC absorption circuit, the resistor is prone to overheating and damage under high-frequency switching conditions, leading to the failure of the protection function.

[0010] On one hand, embodiments of the present invention provide a gallium nitride (GaN) motor controller, comprising: a motor; a power control device connected in series with the motor for controlling the energization or de-energization of the motor, including a GaN switch transistor, wherein the GaN switch transistor has parasitic capacitance; and a resonance cancellation circuit connected to the power control device, including a freewheeling diode, an absorption capacitor, and a discharge resistor, wherein the absorption capacitor and the discharge resistor are connected in parallel, and the freewheeling diode, the absorption capacitor connected in parallel, and the discharge resistor are connected in series, wherein when the GaN switch transistor is in the off-state, the inductor current of the motor is forward-biased through the freewheeling diode, charging the absorption capacitor and causing the voltage of the absorption capacitor to gradually rise; when the GaN switch transistor is in the energy discharge state and the absorption capacitor rises to a predetermined voltage, it discharges through the discharge resistor, converting the stored electrical energy into heat energy for stable dissipation.

[0011] The beneficial effects of the above technical solution are as follows: by optimizing the energy absorption and discharge path, effective suppression of high-frequency resonance and reliable protection of the switching transistor are achieved.

[0012] Based on a further improvement of the above device, the absorption capacitor is used to absorb the resonant energy of the winding inductance of the motor and the parasitic capacitance to suppress voltage spikes, wherein the capacitance value of the absorption capacitor is selected according to the equivalent inductance of the motor, the switching frequency of the gallium nitride switch and the parasitic capacitance.

[0013] Based on a further improvement of the above device, the bleed resistor is used to control the discharge rate of the absorption capacitor to release the resonant energy stored in the absorption capacitor, wherein the resistance value and power of the bleed resistor are selected according to the resonant energy stored in the absorption capacitor, the switching frequency of the gallium nitride switch, and the maximum allowable temperature rise.

[0014] Based on a further improvement of the above device, the freewheeling diode is used to provide a freewheeling path for the inductor current when the gallium nitride switch is turned off, wherein the freewheeling diode is selected as an ultrafast recovery diode or a Schottky diode to reduce the impact of the reverse recovery time on the gallium nitride switch.

[0015] Based on further improvements to the above-mentioned device, the motor may include a DC motor, an electric compressor permanent magnet synchronous motor, a servo motor, or a drone brushless motor.

[0016] Based on a further improvement of the above device, when the motor is a DC motor, the resonance cancellation circuit is connected in parallel between the positive and negative terminals of the DC motor.

[0017] Based on further improvements to the above-mentioned device, when the motor is the permanent magnet synchronous motor of the electric compressor, the gallium nitride motor controller includes a first gallium nitride three-phase inverter for the electric power supply of the new energy vehicle and the resonance elimination circuit is a first resonance elimination circuit. The first gallium nitride three-phase inverter is used to convert the DC voltage provided by the vehicle high-voltage battery into a three-phase AC voltage and provide it to the permanent magnet synchronous motor of the electric compressor. The first resonance elimination circuit is connected in parallel across each gallium nitride switch in the upper and lower gallium nitride switches of each phase bridge arm of the first gallium nitride three-phase inverter.

[0018] The beneficial effects of the above technical solutions are as follows: (1) Resonance suppression effect: the high frequency resonance amplitude is reduced by more than 80%, the voltage oscillation frequency at both ends of the switching tube is reduced from 5MHz (without resonance elimination circuit) to below 1MHz, and the oscillation amplitude is reduced from ±20V to ±3V; (2) Voltage spike protection: the turn-off voltage spike of GaN switching tube is reduced from 125V to below 80V, which is 15% lower than the rated withstand voltage (600V) of the switching tube, and the device lifespan is increased by more than 30%; (3) EMC performance optimization: in the vehicle EMC test, the radiated interference value in the 30MHz~1GHz band is reduced by 15dBμV / m, which meets the electromagnetic compatibility requirements of GB / T 21437.2-2008 vehicle electronic equipment; (4) Energy efficiency maintenance: the additional loss introduced by the resonance elimination circuit is ≤0.5%, and the overall energy efficiency of the electric compressor is ≥95%, which is better than the traditional RC absorption circuit (loss ≥1%).

[0019] Based on further improvements to the above-mentioned device, when the motor is the servo motor, the gallium nitride motor controller includes a three-phase power frequency rectification and filtering module, a second gallium nitride three-phase inverter, and an enhanced resonance cancellation circuit. The resonance cancellation circuit consists of a second resonance cancellation circuit and an enhanced resonance cancellation circuit. The three-phase power frequency rectification and filtering module is used to rectify the three-phase power frequency AC voltage to provide DC voltage via the positive and negative terminals of the DC bus. The second gallium nitride three-phase inverter is used to convert the DC voltage into a three-phase AC voltage and provide it to the servo motor. The second resonance cancellation circuit is connected in parallel across each gallium nitride switch in the upper and lower gallium nitride switches of each phase arm of the second gallium nitride three-phase inverter. The enhanced resonance cancellation circuit is connected in parallel between the positive and negative terminals of the DC bus.

[0020] The beneficial effects of the above technical solutions are as follows: (1) Resonance suppression and current ripple optimization: High-frequency resonance is completely suppressed, the stator current ripple of the motor is reduced from 15% (without resonance elimination circuit) to less than 5%, and the current loop bandwidth is increased to 12kHz, which meets the requirements of high-precision servo control; (2) Position control accuracy improvement: The positioning error of the servo system is reduced from ±0.05mm to ±0.01mm, and the repeatability positioning accuracy is improved by 40%, which is suitable for high-precision application scenarios such as precision machine tools and robot joints; (3) Device reliability assurance: The turn-off voltage spike of GaN switch is reduced from 110V to less than 75V, and the resistance temperature rise is ≤35℃ under full load 1MHz conditions, with no risk of overheating; (4) Enhanced system stability: There is no shutdown failure caused by resonance noise during continuous 24-hour full load operation, and the equipment failure rate is reduced by 60%, which is better than traditional servo controllers.

[0021] Based on further improvements to the above-mentioned device, when the motor is the brushless motor of the drone, the gallium nitride motor controller includes a third gallium nitride three-phase inverter and the resonance elimination circuit is a third resonance elimination circuit. The third gallium nitride three-phase inverter is used to convert the drone lithium battery voltage into a three-phase AC voltage and provide the three-phase AC voltage to the drone brushless motor. The third resonance elimination circuit is co-packaged with the third gallium nitride three-phase inverter and connected in parallel between the drain and source of each phase gallium nitride switching transistor in the third gallium nitride three-phase inverter.

[0022] The beneficial effects of the above technical solutions are as follows: (1) High-frequency resonance suppression: High-frequency resonance above 10MHz is completely suppressed, the voltage waveform of the switching tube has no oscillation, the switching loss is reduced by 25%, and the full-load temperature rise of the controller is reduced from 65℃ to below 40℃; (2) Improved endurance: The energy efficiency of the controller is increased from 93% to 95.5%, and the endurance of the UAV on a single charge is extended by 8%~10%, meeting the long endurance requirements of industrial-grade UAVs; (3) Navigation and communication reliability: The GPS navigation and positioning accuracy error is ≤1m, and the bit error rate of the data transmission signal is reduced from 10-4 Reduced to 10 -6 (4) Lightweight adaptation: The volume of the resonance elimination circuit is only 4mm×2.5mm. After being co-packaged with the GaN module, the overall volume of the controller is reduced by 30% compared with the traditional solution, which meets the requirements of lightweight design of UAV.

[0023] On the other hand, embodiments of the present invention provide a resonance cancellation method for the gallium nitride motor controller described in the above embodiments, comprising: providing a turn-on control signal to the gate of a gallium nitride switch in a power control device, causing the gallium nitride switch to turn on, controlling the motor to be powered on, the freewheeling diode to be in the off state, and the resonance cancellation circuit not working; providing a turn-off control signal to the gallium nitride switch, causing the gallium nitride switch to switch from the turn-on stage to the turn-off stage, controlling the motor to be powered off, the inductor current of the motor to conduct forward through the freewheeling diode, charging the absorption capacitor and causing the voltage of the absorption capacitor to gradually rise; when the absorption capacitor rises to a predetermined voltage, the gallium nitride switch switches from the turn-off stage to the energy discharge stage, discharging through the discharge resistor, converting the stored electrical energy into heat energy for stable dissipation.

[0024] Compared with the prior art, the present invention can achieve at least one of the following beneficial effects: 1. By optimizing the energy absorption and discharge paths, effective suppression of high-frequency resonance and reliable protection of the switching transistor are achieved.

[0025] 2. Resonance Suppression Effect: High-frequency resonance amplitude is reduced by more than 80%, the voltage oscillation frequency across the switching transistor drops from 5MHz (without resonance cancellation circuit) to below 1MHz, and the oscillation amplitude drops from ±20V to ±3V; Voltage Spike Protection: The turn-off voltage spike of the GaN switching transistor drops from 125V to below 80V, which is 15% lower than the rated withstand voltage (600V) of the switching transistor, and the device lifespan is increased by more than 30%; EMC Performance Optimization: In automotive EMC testing, the radiated interference value in the 30MHz~1GHz frequency band is reduced by 15dBμV / m, meeting the electromagnetic compatibility requirements of GB / T 21437.2-2008 automotive electronic equipment; Energy Efficiency Maintenance: The additional loss introduced by the resonance cancellation circuit is ≤0.5%, and the overall energy efficiency of the electric compressor is ≥95%, which is better than the traditional RC absorption circuit (loss ≥1%).

[0026] 3. Resonance Suppression and Current Ripple Optimization: High-frequency resonance is completely suppressed, and the motor stator current ripple is reduced from 15% (without resonance cancellation circuit) to below 5%. The current loop bandwidth is increased to 12kHz, meeting the requirements of high-precision servo control. Position Control Accuracy Improvement: The servo system positioning error is reduced from ±0.05mm to ±0.01mm, and the repeatability is improved by 40%, making it suitable for high-precision applications such as precision machine tools and robot joints. Device Reliability Guarantee: The turn-off voltage spike of the GaN switch is reduced from 110V to below 75V, and the resistance temperature rise is ≤35℃ under full load at 1MHz, with no risk of overheating. Enhanced System Stability: No downtime caused by resonance noise during continuous 24-hour full-load operation, reducing the equipment failure rate by 60%, which is superior to traditional servo controllers.

[0027] 4. High-frequency resonance suppression: High-frequency resonances above 10MHz are completely suppressed, the switching transistor voltage waveform is oscillating, switching losses are reduced by 25%, and the controller's full-load temperature rise is reduced from 65℃ to below 40℃; Improved endurance: The controller's energy efficiency is improved from 93% to 95.5%, and the drone's single-charge endurance is extended by 8%~10%, meeting the long-endurance requirements of industrial-grade drones; Navigation and communication reliability: GPS navigation and positioning accuracy error ≤1m, and the data transmission signal bit error rate is reduced from 10 -4 Reduced to 10 -6 There is no risk of flight loss of control due to resonance noise; lightweight adaptation: the resonance cancellation circuit is only 4mm×2.5mm in size. After being co-packaged with the GaN module, the overall size of the controller is reduced by 30% compared with the traditional solution, which meets the requirements of lightweight design of UAVs.

[0028] In this invention, the above-described technical solutions can be combined with each other to achieve more preferred combinations. Other features and advantages of this invention will be set forth in the following description, and some advantages may become apparent from the description or be learned by practicing the invention. The objects and other advantages of this invention can be realized and obtained from what is particularly pointed out in the description and drawings. Attached Figure Description

[0029] The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. Throughout the drawings, the same reference numerals denote the same parts.

[0030] Figure 1 is a circuit diagram of an existing motor controller without buffer protection when the switching transistor is turned on; Figure 2 The circuit diagram for an existing motor controller without buffer protection when the switching transistor is turned off; Figure 3 A motor controller with an RC snubber circuit; Figure 4This is a circuit topology diagram of a GaN controller for an electric compressor in a new energy vehicle according to an embodiment of the present invention; Figure 5 This is a circuit topology diagram of a GaN motor controller for an industrial servo system according to an embodiment of the present invention; Figure 6 This is a circuit topology diagram of a GaN controller for a brushless motor in a drone, according to an embodiment of the present invention. Figure 7 This is a circuit diagram of a gallium nitride motor controller according to an embodiment of the present invention when the gallium nitride switching transistor is turned on; Figure 8 This is a circuit diagram of a gallium nitride motor controller according to an embodiment of the present invention when the gallium nitride switching transistor is turned off; Figure 9 This is a graph showing the comparison of turn-off voltage spikes of the switching transistor in a GaN motor controller according to an embodiment of the present invention. Detailed Implementation

[0031] Preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings, which form part of this application and are used together with the embodiments of the present invention to illustrate the principles of the present invention, but are not intended to limit the scope of the present invention.

[0032] refer to Figure 7 and Figure 8 A specific embodiment of the present invention discloses a gallium nitride (GaN) motor controller, comprising: a motor M; a power control device connected in series with the motor for controlling the energization or de-energization of the motor M, including a gallium nitride switching transistor, wherein the gallium nitride switching transistor has a parasitic capacitance Coss, that is, the parasitic capacitance Coss is connected in parallel between the drain and source of the gallium nitride switching transistor; and a resonance cancellation circuit connected to the power control device, including a freewheeling diode D, an absorption capacitor C, and a discharge resistor R, wherein the absorption capacitor C and the discharge resistor R are connected in parallel, and the freewheeling diode D, the absorption capacitor C connected in parallel, and the discharge resistor R are connected in series. Specifically, when the gallium nitride switch is in the on-state, the freewheeling diode D is in the off-state, and the resonance cancellation circuit does not work; when the gallium nitride switch is in the off-state, the inductor current of the motor M is forward-biased through the freewheeling diode D, charging the absorption capacitor C and causing the voltage of the absorption capacitor C to gradually rise; when the gallium nitride switch is in the energy discharge stage and the absorption capacitor C rises to the predetermined voltage, it is discharged through the discharge resistor R, converting the stored electrical energy into heat energy for stable dissipation.

[0033] The absorption capacitor C is used to absorb the resonant energy of the motor winding inductance L and parasitic capacitance Coss to suppress voltage spikes. The capacitance value of the absorption capacitor C is selected according to the equivalent inductance L of the motor winding, the switching frequency of the gallium nitride switch and the parasitic capacitance Coss.

[0034] The bleed resistor R is used to control the discharge rate of the absorption capacitor C to release the resonant energy stored in the absorption capacitor C, thereby achieving smooth energy dissipation. The resistance value and power of the bleed resistor R are selected based on the resonant energy stored in the absorption capacitor C, the switching frequency of the gallium nitride switch, and the maximum allowable temperature rise.

[0035] The freewheeling diode D is used to provide a freewheeling path for the inductor current when the gallium nitride switch is turned off. The freewheeling diode D is selected as an ultrafast recovery diode or a Schottky diode to reduce the impact of reverse recovery time on the gallium nitride switch.

[0036] Compared with the prior art, the gallium nitride motor controller provided in this embodiment achieves effective suppression of high-frequency resonance and reliable protection of the switching transistor by optimizing the energy absorption and discharge path.

[0037] The motors include DC motors, permanent magnet synchronous motors for electric compressors, servo motors, or brushless motors for drones.

[0038] (1) Reference Figure 7 and Figure 8 When the motor is a DC motor, the resonance cancellation circuit is connected in parallel between the positive and negative terminals of the DC motor. Specifically, the anode of the freewheeling diode D in the resonance cancellation circuit is connected to the power control device, that is, the anode of the freewheeling diode D in the resonance cancellation circuit is connected to the drain D of the gallium nitride switch, the source S of the gallium nitride switch is grounded, and the gate G of the gallium nitride switch receives the PWM control signal. The cathode of the freewheeling diode D is connected to the first terminal of the parallel absorption capacitor C and the first terminal of the discharge resistor R, and the second terminal of the parallel absorption capacitor C and the second terminal of the discharge resistor R are connected to the power supply voltage (48V).

[0039] (2) Reference Figure 4 When the motor is an electric compressor permanent magnet synchronous motor (i.e., module 3), the gallium nitride motor controller includes a first gallium nitride three-phase inverter for the electric compressor (i.e., module 2) and a first resonance elimination circuit (i.e., module 4). The first gallium nitride three-phase inverter is used to convert the DC voltage provided by the on-board high-voltage battery into a three-phase AC voltage and provide it to the electric compressor permanent magnet synchronous motor. The first resonance elimination circuit is connected in parallel across each gallium nitride switch in the upper and lower gallium nitride switches of each phase arm of the first gallium nitride three-phase inverter.

[0040] (3) Reference Figure 5When the motor is a servo motor 3, the gallium nitride motor controller includes a three-phase power frequency rectification and filtering module 1, a second gallium nitride three-phase inverter 2, and an enhanced resonance elimination circuit (i.e., bus-side resonance elimination 4). The resonance elimination circuit is the second resonance elimination circuit (i.e., bridge arm-side resonance elimination 4). The three-phase power frequency rectification and filtering module 1 is used to rectify the three-phase power frequency AC voltage to provide DC voltage through the positive and negative terminals of the DC bus. The second gallium nitride three-phase inverter 2 is used to convert the DC voltage into a three-phase AC voltage and provide it to the servo motor. The second resonance elimination circuit (i.e., bridge arm-side resonance elimination 4) is connected in parallel across each gallium nitride switch in the upper and lower gallium nitride switches of each phase bridge arm of the second gallium nitride three-phase inverter. The enhanced resonance elimination circuit (i.e., bus-side resonance elimination 4) is connected in parallel between the positive and negative terminals of the DC bus.

[0041] (4) Reference Figure 6 When the motor is a brushless motor 3 for the drone, the gallium nitride motor controller includes a third gallium nitride three-phase inverter 2 and a third resonance elimination circuit. The third gallium nitride three-phase inverter is used to convert the drone lithium battery voltage into a three-phase AC voltage and provide the three-phase AC voltage to the drone brushless motor. The third resonance elimination circuit is co-packaged with the third gallium nitride three-phase inverter and connected in parallel between the drain and source of each phase gallium nitride switching transistor in the third gallium nitride three-phase inverter.

[0042] Another specific embodiment of the present invention discloses a resonance cancellation method for the gallium nitride motor controller of the above embodiment. The resonance cancellation method includes: providing a turn-on control signal to the gate of the gallium nitride switch in the power control device, so that the gallium nitride switch is turned on, controlling the motor to be powered on, the freewheeling diode is in the cut-off state, and the resonance cancellation circuit does not work; providing a turn-off control signal to the gallium nitride switch, the gallium nitride switch is switched from the turn-on stage to the turn-off stage, controlling the motor to be powered off, the inductor current of the motor is forward-biased through the freewheeling diode, charging the absorption capacitor and causing the voltage of the absorption capacitor to gradually rise; when the absorption capacitor rises to a predetermined voltage, the gallium nitride switch is switched from the turn-off stage to the energy discharge stage, and the stored electrical energy is discharged through the discharge resistor, converting the stored electrical energy into heat energy for stable dissipation.

[0043] The following text uses specific examples for reference. Figures 4 to 8 The gallium nitride motor controller according to embodiments of the present invention will be described in detail.

[0044] The core advantage of the resonance cancellation circuit of this invention lies in its adaptation to the high-frequency switching characteristics of GaN devices (such as 500kHz and above). By optimizing the energy absorption and discharge paths, it accurately suppresses the high-frequency resonance formed by the motor inductance and the parasitic capacitance of the switching transistor, while reducing voltage spikes in the switching transistor and minimizing system losses. The following describes its implementation and technical effects in detail, using three typical application scenarios as examples.

[0045] Example 1: GaN controller applied to electric compressors in new energy vehicles 1. Scene Background The electric compressor in new energy vehicles is a core component of the air conditioning system. Its drive motor is a permanent magnet synchronous motor with an operating voltage range of 280V~420V (high voltage platform). To improve energy efficiency and power density, a GaN controller with a switching frequency of 500kHz is used. In this scenario, the equivalent inductance of the motor (50μH~80μH) and the parasitic capacitance of the GaN switch (Coss≈100pF) are prone to high-frequency resonance during switching, resulting in excessively high turn-off voltage spikes (up to 120V or more), posing a risk to device reliability. At the same time, the resonant noise can interfere with the vehicle's electronic system.

[0046] 2. Circuit topology diagram of GaN controller for electric compressor in new energy vehicles (including resonance cancellation circuit) refer to Figure 4 1 is the vehicle-mounted high-voltage battery (350V), 2 is the GaN three-phase bridge inverter (the core component is GaNHEMT), 3 is the permanent magnet synchronous motor of the electric compressor, 4 is the resonance elimination circuit of this invention, 5 is the current sampling circuit, and 6 is the controller MCU. Among them, the resonance elimination circuit 4 is connected in parallel to the upper and lower switching transistors of each phase bridge arm of the GaN inverter (i.e., between the nodes of the three-phase bridge arms A, B, and C and the positive and negative terminals of the DC bus).

[0047] The specific parameters for the resonance cancellation circuit 4 are as follows: absorption capacitor C = 2.2nF (high-frequency X7R ceramic capacitor, withstand voltage 600V), discharge resistor R = 10Ω (2W low inductance alloy resistor), Schottky diode D (trr < 10ns, withstand voltage 600V), forming an RC-D clamping resonance cancellation structure.

[0048] 3. Corresponding function of resonance cancellation circuit (1) Suppressing bridge arm resonance: When the electric compressor motor starts and the load changes suddenly, the LC resonant circuit formed by the motor inductance and the parasitic capacitance of the switching tube will generate high-frequency oscillation. This circuit absorbs the resonant energy quickly through the absorption capacitor C, so as to avoid the energy from continuously oscillating and amplifying in the LC circuit. (2) Clamping the voltage spike of the switch: When the GaN switch is turned off at high frequency, the freewheeling energy of the motor inductor is prone to generate an overvoltage spike at both ends of the switch. The resonance elimination circuit clamps the voltage spike within a safe range through the fast conduction characteristic of diode D, and at the same time absorbs the voltage rise rate by capacitor C. (3) Stable energy dissipation: The resonant energy stored in the absorption capacitor is slowly dissipated through the discharge resistor R to avoid energy accumulation leading to an increase in capacitor voltage. At the same time, the low inductance and resistance design prevents the generation of new high-frequency interference during the discharge process, which is compatible with vehicle electromagnetic compatibility (EMC) requirements.

[0049] 4. Technical Effects (1) Resonance suppression effect: The high-frequency resonance amplitude is reduced by more than 80%, the voltage oscillation frequency across the switching transistor is reduced from 5MHz (without resonance elimination circuit) to below 1MHz, and the oscillation amplitude is reduced from ±20V to ±3V; (2) Voltage spike protection: The turn-off voltage spike of the GaN switch drops from 125V to below 80V, which is 15% lower than the rated withstand voltage (600V) of the switch, and the device lifespan is increased by more than 30%. (3) EMC performance optimization: In the vehicle EMC test, the radiated interference value in the 30MHz~1GHz band was reduced by 15dBμV / m, which meets the electromagnetic compatibility requirements of GB / T 21437.2-2008 vehicle electronic equipment; (4) Energy efficiency maintenance: The additional loss introduced by the resonance elimination circuit is ≤0.5%, and the overall energy efficiency of the electric compressor is ≥95%, which is better than the traditional RC absorption circuit (loss ≥1%).

[0050] Example 2: GaN motor controller applied to industrial servo systems 1. Scene Background Industrial servo systems (such as machine tools and robot joint drives) have extremely high requirements for the dynamic response speed and control accuracy of motor control, employing GaN controllers with a switching frequency of 1MHz to improve the current loop bandwidth (≥10kHz). In this scenario, the multi-resonant circuit formed by the servo motor's equivalent inductance (20μH~50μH), the parasitic inductance of the circuit, and the parasitic capacitance of the GaN switch leads to increased current ripple and decreased position control accuracy. At the same time, the noise generated by high-frequency resonance can affect the signal acquisition of precision sensing devices such as encoders.

[0051] 2. Industrial servo system GaN motor controller circuit topology diagram (including resonance cancellation circuit) refer to Figure 51 is a three-phase power frequency rectifier and filter module (output DC voltage 220V), 2 is a GaN half-bridge module (a total of 6 GaN switching transistors, forming a three-phase inverter), 3 is a servo motor, 4 is a resonance cancellation circuit, 5 is an encoder (position detection), and 6 is a servo controller. Among them, the resonance cancellation circuit 4 adopts a dual layout of "parallel bridge arm + parallel bus": a set of resonance cancellation circuits is connected in parallel across the upper and lower switching transistors of each phase bridge arm, and an enhanced resonance cancellation circuit is connected in parallel between the positive and negative terminals of the DC bus.

[0052] Resonance cancellation circuit parameter selection: bridge arm side absorption capacitor C1=1.8nF (high frequency ceramic capacitor), discharge resistor R1=12Ω (1W low inductance resistor); bus side absorption capacitor C2=4.7nF (electrolytic + ceramic composite capacitor), discharge resistor R2=8Ω (2W resistor); all diodes are Schottky diodes (trr<8ns).

[0053] 3. Corresponding function of resonance cancellation circuit (1) Multiple resonance suppression: For the LC resonance on the bridge arm side (motor inductance + switch Coss) and the resonance on the bus side (line parasitic inductance + bus capacitance), the full-link resonance energy absorption is achieved through a dual layout to avoid the resonance being coupled and amplified between different circuits; (2) Improve current control accuracy: High frequency resonance will increase the stator current ripple of the motor, which will affect the sampling accuracy of the current loop. The resonance elimination circuit can make the current waveform smoother by suppressing voltage oscillation and improve the dynamic response speed of the current loop. (3) Protect precision sensing equipment: High-frequency electromagnetic interference generated by resonance can enter the encoder signal line, causing position detection error. The resonance elimination circuit reduces high-frequency noise radiation and ensures the stability and accuracy of the encoder signal. (4) Adapting to high-frequency switching conditions: For 1MHz high-frequency switching, the circuit selects components with low parasitic parameters to avoid becoming a new resonant source, while quickly absorbing the instantaneous energy during the switching process.

[0054] 4. Technical Effects (1) Resonance suppression and current ripple optimization: High-frequency resonance is completely suppressed, the stator current ripple of the motor is reduced from 15% (without resonance elimination circuit) to below 5%, and the current loop bandwidth is increased to 12kHz to meet the requirements of high-precision servo control. (2) Improved position control accuracy: The positioning error of the servo system is reduced from ±0.05mm to ±0.01mm, and the repeatability is improved by 40%, which is suitable for high-precision application scenarios such as precision machine tools and robot joints; (3) Device reliability assurance: The turn-off voltage spike of the GaN switch drops from 110V to below 75V, and the temperature rise of the resistor is ≤35℃ under full load 1MHz conditions, with no risk of overheating; (4) Enhanced system stability: No downtime caused by resonance noise during continuous 24-hour full-load operation, reducing equipment failure rate by 60%, which is better than traditional servo controllers.

[0055] Example 3: Application in GaN controller for brushless motors in drones 1. Scene Background Unmanned aerial vehicles (UAVs) (multi-rotor and industrial mapping UAVs) have stringent requirements for lightweight, miniaturized, and high-efficiency motor controllers. GaN controllers with a switching frequency of 600kHz are used to reduce the size of passive components. In this scenario, the equivalent inductance of the UAV's brushless motor is small (5μH~20μH), resulting in a higher resonant frequency (up to 10MHz or more) with the parasitic capacitance of the GaN switch (Coss≈80pF). This easily leads to increased switching losses and severe controller overheating. Furthermore, the noise generated by high-frequency resonance can interfere with the UAV's navigation and communication systems.

[0056] 2. Circuit topology diagram of GaN controller for brushless motor of UAV (including resonance cancellation circuit) refer to Figure 6 1 is the drone's lithium battery (22.2V, 6S), 2 is the GaN three-phase inverter (integrated GaN module), 3 is the drone's brushless motor, 4 is the resonance cancellation circuit, 5 is the battery management module (BMS), and 6 is the flight controller. The resonance cancellation circuit 4 adopts a miniaturized integrated design, is co-packaged with the GaN module, and is connected in parallel between the drain and source of each phase GaN switch, reducing the impact of parasitic inductance on the resonance cancellation effect.

[0057] Resonance cancellation circuit parameter selection: absorption capacitor C=1.2nF (miniature high-frequency ceramic capacitor, 0603 package), discharge resistor R=15Ω (0805 package, low inductance and resistance, 0.5W power), Schottky diode D (ultra-miniature package, trr<10ns), overall circuit size ≤5mm×3mm, suitable for the lightweight requirements of drones.

[0058] 3. Corresponding function of resonance cancellation circuit (1) Precise suppression of high frequency resonance: In view of the characteristics of small inductance and high resonance frequency of brushless motor of drone, a miniaturized and close-to-device layout resonance elimination circuit is used to quickly absorb high frequency resonance energy above 10MHz and avoid the surge in switching loss caused by resonance. (2) Reduce controller heat generation: High-frequency resonance will increase the switching loss of the switching transistor, resulting in excessive temperature rise of the controller and affecting the drone's endurance. The resonance elimination circuit reduces the switching loss by suppressing resonance and reduces the heat generation of the controller. (3) Ensure stable navigation and communication: High-frequency noise generated by resonance will interfere with GPS navigation signals and UAV data transmission signals. Resonance elimination circuit reduces electromagnetic radiation and avoids navigation drift and communication interruption. (4) Adapted to lightweight packaging: Adopting miniaturized components and co-package design, without increasing the size of the controller, meeting the stringent requirements of UAV for device miniaturization.

[0059] 4. Technical Effects (1) High frequency resonance suppression: High frequency resonance above 10MHz is completely suppressed, the voltage waveform of the switching tube has no oscillation, the switching loss is reduced by 25%, and the full-load temperature rise of the controller is reduced from 65℃ to below 40℃; (2) Improved battery life: The controller's energy efficiency has been increased from 93% to 95.5%, and the drone's battery life on a single charge has been extended by 8% to 10%, meeting the long-endurance requirements of industrial-grade drones; (3) Navigation and communication reliability: GPS navigation and positioning accuracy error ≤ 1m, data transmission signal bit error rate from 10 -4 Reduced to 10 -6 Risk of flight runaway due to cause-effect resonance noise; (4) Lightweight adaptation: The volume of the resonance cancellation circuit is only 4mm×2.5mm. After being co-packaged with the GaN module, the overall volume of the controller is reduced by 30% compared with the traditional solution, which meets the requirements of lightweight design of UAV.

[0060] refer to Figure 7 The resonance cancellation circuit of this invention includes a buffer absorption branch connected in parallel across the motor terminals. This branch is composed of a diode D, an absorption capacitor C, and a discharge resistor R connected in series. Diode D: An ultrafast recovery diode or a Schottky diode is selected to provide a freewheeling path for the inductor current when the switching transistor is turned off; Capacitor C: Used to absorb the energy stored in the inductor and suppress voltage spikes; Resistor R: Used to control the discharge rate of the capacitor to achieve stable energy dissipation.

[0061] The following text provides a detailed explanation of the three operating stages (conduction / turn-off / energy discharge) of the resonance cancellation circuit.

[0062] Step 1: Switch conduction stage This paper combines three application scenarios: electric compressors for new energy vehicles, industrial servo systems, and brushless motors for drones. It provides a detailed explanation of the circuit working logic, the role of resonance elimination circuit, and the impact of each stage during the switching transistor conduction, switching transistor turn-off, and energy dissipation stages. It also relates to the topological characteristics and parameter differences of each scenario.

[0063] Example 1: GaN Controller for Electric Compressors in New Energy Vehicles Core topology: Three-phase bridge arm independent parallel resonance cancellation circuit (C=2.2nF, R=10Ω, D:trr<10ns), high voltage DC bus 350V, switching frequency 500kHz.

[0064] 1. Switch conduction stage Work logic: (1) The controller MCU outputs a drive signal, the GaN switch is turned on, the DC bus voltage is applied to the motor winding, and the current forms a loop through the positive terminal of the bus → the upper bridge arm switch → the motor phase line → the lower bridge arm switch → the negative terminal of the bus, and the motor inductor stores energy.

[0065] (2) In the resonance cancellation circuit, the Schottky diode D is forward-biased, the absorption capacitor C is short-circuited and no energy is stored; no current flows through the discharge resistor R and no loss is generated.

[0066] Function of resonance cancellation circuit: (1) The fast conduction characteristic of diode D prevents the absorption capacitor C from being charged at the moment the switch is turned on, thus preventing the capacitor charging current from being superimposed on the motor drive current and causing current spikes.

[0067] (2) Select a low inductance resistor R to avoid the formation of a new resonant circuit due to the parasitic inductance of the resistor and the capacitance during the conduction stage.

[0068] Phase Impact (1) Positive effects: The motor winding current rises steadily without additional spike interference, the current sampling circuit collects signals accurately, and the MCU closed-loop control responds quickly; the resonance elimination circuit is lossless, and the system energy efficiency remains high.

[0069] (2) Scenario adaptability: Under high-voltage conditions in vehicles, avoid the impact of conduction current spikes on GaN switching transistors, improve the voltage withstand reliability of devices, and meet the long life requirements of vehicle electronic equipment.

[0070] 2. Switch turn-off stage Working Logic (1) When the drive signal is removed, the GaN switch is quickly turned off. Due to the characteristic that the motor winding inductance current cannot change abruptly, a reverse induced electromotive force is generated, which forms an LC resonant circuit with the parasitic capacitance Coss of the switch. If the resonance cancellation circuit is ignored, a voltage spike of more than 120V will be generated.

[0071] (2) The induced electromotive force causes the voltage across the switch tube to rise rapidly. When the voltage exceeds the voltage across the absorption capacitor C, the Schottky diode D is reverse cut off, and the induced electromotive force charges C. The resonant energy is quickly transferred to the absorption capacitor.

[0072] Resonance cancellation circuit function (1) Core suppression of resonance: The absorption capacitor C is directly connected in parallel across the switching transistor to preferentially absorb the resonance energy of the motor inductance and Coss, thus blocking the oscillation amplification of the resonance energy in the LC circuit.

[0073] (2) Clamping voltage spike: The charging process of capacitor C buffers the rise rate of voltage across the switching transistor. Combined with the fast turn-off characteristic of diode D, the voltage spike is suppressed from 120V to the 70~80V range.

[0074] Phase Impact (1) Positive effects: The turn-off voltage spike of the switching transistor drops to a safe range (15% lower than the rated withstand voltage of 600V), the risk of device breakdown is reduced, and the service life is increased by more than 30%; the high-frequency resonance amplitude is reduced by 80%, and the radiated interference value in the 30MHz~1GHz band in the vehicle EMC test is reduced by 15dBμV / m.

[0075] (2) Potential loss control: The loss generated during the capacitor charging process is minimal, and the system efficiency decreases by no more than 0.5%, meeting the high energy consumption ratio requirement of the vehicle compressor.

[0076] 3. Energy release phase Working Logic (1) The resonant energy stored in the absorption capacitor C is slowly released through the discharge resistor R. The current path is: positive terminal of capacitor C → resistor R → negative terminal of capacitor C, forming a closed-loop discharge circuit.

[0077] (2) The discharge process continues until the next switching transistor is turned on, ensuring that the initial voltage of capacitor C is close to 0V in the next working cycle to avoid energy accumulation.

[0078] Resonance cancellation circuit function (1) Stable energy discharge: 10Ω low inductance resistor controls the discharge current to avoid excessive discharge and new voltage fluctuations, while preventing excessive temperature rise of the resistor.

[0079] (2) Avoid EMC interference: Select low inductance resistors to prevent the parasitic inductance of the resistor from resonating with the capacitor during the discharge process and reduce high-frequency noise radiation.

[0080] Phase Impact (1) Positive effects: The temperature rise of the resistor under full load is stable at 30~40℃, with no risk of overheating; the energy of the capacitor is completely discharged, the resonance suppression effect of the next switching cycle is stable, and there is no cumulative error in the circuit operation.

[0081] (2) Scene adaptability: The temperature fluctuation of the vehicle environment is large (-40℃~85℃), and the temperature rise of the resistor is controlled within 40℃ to avoid the high temperature affecting the working stability of the surrounding electronic components (such as MCU and sampling circuit).

[0082] Example 2: GaN Motor Controller for Industrial Servo Systems Core topology: Bridge arm + bus dual resonance cancellation circuit (bridge arm side; bus side), DC bus 220V, switching frequency 1MHz.

[0083] 1. Switch conduction stage Working Logic (1) The servo controller outputs a PWM drive signal, the GaN switch is turned on, the bus voltage is applied to the servo motor winding, the current is quickly established, and the motor shaft begins to be precisely positioned; because the switching frequency is as high as 1MHz, the current loop bandwidth is required to be ≥10kHz.

[0084] (2) The diode D1 of the bridge arm side resonance elimination circuit is forward conducting and C1 is short-circuited; the diode D2 of the bus side resonance elimination circuit is forward conducting and C2 is short-circuited. Neither circuit stores any energy.

[0085] Resonance cancellation circuit function (1) Bridge arm side: D1 fast conduction avoids C1 charging interference motor current ripple and ensures current loop sampling accuracy; R1 low inductance characteristics prevent resonance with bus parasitic inductance.

[0086] (2) Busbar side: D2 conducts short circuit to C2 to avoid resonance between busbar capacitance and line inductance, thus ensuring stable busbar voltage.

[0087] Phase Impact (1) Positive impact: The stator current ripple of the motor is reduced from 15% to below 5%, and the dynamic response speed of the current loop is increased to 12kHz, which meets the micron-level positioning requirements of precision machine tools; the dual circuit has no conduction loss, and the system energy efficiency is ≥95%.

[0088] (2) Scene adaptability: Industrial servo is sensitive to current ripple. There is no additional interference during the conduction stage, which directly improves the position control accuracy and reduces the repeatability error from ±0.05mm to ±0.01mm.

[0089] 2. Switch turn-off stage Working Logic (1) When the GaN switch is turned off at high frequency, the motor inductance and the Coss of the switch generate bridge arm resonance. At the same time, the parasitic inductance of the bus line and the bus capacitance generate bus resonance. The double resonance coupling can easily lead to the voltage oscillation amplitude exceeding 110V.

[0090] (2) Bridge arm side: The induced electromotive force causes the voltage of the switch tube to rise, D1 is cut off, and C1 absorbs the resonant energy of the bridge arm; Bus side: When the bus voltage oscillates, D2 is cut off, and C2 absorbs the resonant energy of the bus. The dual circuits work simultaneously to block the resonant coupling.

[0091] Resonance cancellation circuit function (1) Full-link resonance suppression: The bridge arm side targets the motor inductance-Coss resonance, and the bus side targets the line inductance-bus capacitance resonance. The dual layout covers all nodes of the power circuit to avoid resonance amplification between different circuits.

[0092] (2) Precisely clamping spikes: The voltage spikes of the switching transistors on the bridge arm side are reduced from 110V to below 75V, and the voltage oscillation amplitude of the bus on the bus side is reduced from ±20V to ±3V.

[0093] Phase Impact (1) Positive effects: High-frequency resonance is completely suppressed, the encoder signal is free from noise interference, and the position detection accuracy is improved by 40%; the peak voltage of the switching transistor is reduced, the resistance temperature rise is ≤35℃ under full load 1MHz conditions, and the equipment can run continuously for 24 hours without failure.

[0094] (2) Scene adaptability: The electromagnetic environment in industrial sites is complex. The dual resonance elimination circuit improves the system's anti-interference ability and reduces the failure rate by 60%, which is better than traditional servo controllers.

[0095] 3. Energy release phase Working Logic (1) The capacitor C1 on the bridge arm side discharges energy through R1, and the capacitor C2 on the bus side discharges energy through R2. The two discharge circuits work independently and do not interfere with each other.

[0096] (2) The discharge time constant is matched with a 1MHz switching frequency to ensure that energy release is completed before the next conduction cycle.

[0097] Resonance cancellation circuit function (1) R1=12Ω on the bridge arm side to control the discharge rate and avoid the bridge arm voltage fluctuation caused by too fast discharge; R2=8Ω on the bus side to quickly discharge the bus resonant energy and ensure the bus voltage stability.

[0098] (2) Both resistors are low inductance type to prevent new high frequency interference from being generated during the discharge process.

[0099] Phase Impact (1) Positive effects: Dual-path discharge has no energy accumulation and the resonance suppression effect is stable; the resistance temperature rise is controllable and there is no risk of overheating during long-term operation in industrial environments; the system efficiency decreases by ≤0.4%, meeting the requirements of industrial energy conservation.

[0100] (2) Scene adaptability: The servo system needs to start and stop frequently and rotate in both directions. The stability of the energy release phase directly determines the dynamic response speed of the system, avoiding control lag caused by energy accumulation.

[0101] Example 3: GaN Controller for Brushless Motors in UAVs Core topology: Miniature co-packaged resonant cancellation circuit (D:trr<10ns), 22.2V lithium battery, 600kHz switching frequency, circuit size 4mm×2.5mm.

[0102] 1. Switch conduction stage Working Logic (1) The flight controller outputs a drive signal, the integrated GaN switch is turned on, the lithium battery voltage is applied to the brushless motor winding, and the motor rotates at high speed to provide lift; due to the lightweight requirements of UAVs, the controller size is limited and parasitic parameters are sensitive.

[0103] (2) In the resonance cancellation circuit, the diode D is forward-biased, the absorption capacitor C is short-circuited, and there is no energy storage; the 15Ω miniature resistor R has no current flowing through it, and the circuit has no conduction loss due to no additional volume occupation.

[0104] Resonance cancellation circuit function (1) The ultra-miniature package (0603) and co-package design of diode D reduce the parasitic inductance of the line and avoid resonance with GaN switch during the conduction stage.

[0105] (2) The miniaturization of capacitor C (0603 package) ensures that the controller volume is not increased when co-packaged, which meets the requirements of lightweight UAV.

[0106] Phase Impact (1) Positive impact: The motor drive current is stable with no extra spikes, the power output of the UAV is stable, and the flight attitude control is precise; there is no conduction loss in the circuit, and the controller energy efficiency is improved to 95.5%.

[0107] (2) Scene adaptability: The co-package design reduces the overall size of the controller by 30%, reduces the load on the drone, and extends the battery life by 8%~10% on a single charge.

[0108] 2. Switch turn-off stage Working Logic (1) The GaN switch turns off quickly, and the equivalent inductance of the brushless motor of the UAV is small (5μH~20μH), forming a high-frequency resonance of more than 10MHz with the Coss of the switch. If there is no resonance elimination circuit, the switching loss will surge and the controller temperature will rise to more than 65℃.

[0109] (2) The induced electromotive force causes the voltage of the switching transistor to rise, the diode D is reverse cut off, and the miniature capacitor C quickly absorbs the high-frequency resonance energy. Due to the co-package layout, the energy transmission path is extremely short, and the effect of parasitic inductance can be ignored.

[0110] Resonance cancellation circuit function (1) Precise suppression of high frequency resonance: For ultra-high resonance frequencies above 10MHz, the high frequency characteristics of the miniature capacitor C are excellent, which can quickly respond and absorb energy to block resonance oscillation.

[0111] (2) Near-device layout reduces losses: The co-package design shortens the connection path between the resonance cancellation circuit and the switching transistor, minimizing parasitic inductance and avoiding losses during energy transfer.

[0112] Phase Impact (1) Positive effects: High-frequency resonance above 10MHz is completely suppressed, switching losses are reduced by 25%, the full-load temperature rise of the controller is reduced from 65℃ to below 40℃; the voltage spike of the switching tube is reduced from 90V to below 65V, and the reliability of the device is improved.

[0113] (2) Scene adaptability: The UAV experiences severe vibrations during flight. The co-package design avoids resonance cancellation failure caused by loose wiring, while reducing electromagnetic radiation. The GPS navigation and positioning accuracy error is ≤1m, and the data transmission signal bit error rate is reduced from 10. -4 Reduced to 10 -6 .

[0114] 3. Energy release phase Working Logic (1) The resonant energy stored in the miniature capacitor C is slowly discharged through the 15Ω miniature resistor R. Due to the small capacitance (1.2nF) and short discharge time, it is matched with a 600kHz switching frequency.

[0115] (2) Under the co-package layout, the discharge loop path is short, there is no extra parasitic parameter interference, and the energy discharge efficiency is high.

[0116] Resonance cancellation circuit function (1) A 15Ω resistor controls the discharge current to prevent voltage fluctuations caused by excessively fast discharge of the miniature capacitor; the resistor is selected as a 0805 package low inductance type to prevent new high-frequency noise from being generated during the discharge process.

[0117] (2) Select miniaturized components to ensure that the temperature rise of the resistor during the discharge stage is ≤35℃, with no risk of overheating.

[0118] Phase Impact (1) Positive effects: Energy is rapidly discharged without accumulation, and the resonance suppression effect is stable in the next switching cycle; the temperature rise of the resistor is controllable, and the controller has no overheating alarm during long-term flight of the UAV (≥2 hours).

[0119] (2) Scene adaptability: The lithium battery capacity of the UAV is limited, and the loss during the discharge stage is minimal (system efficiency decrease ≤0.3%), which further improves the endurance and meets the long endurance requirements of industrial-grade mapping UAVs.

[0120] refer to Figure 7 When the PWM signal drives the gate G of the switching transistor to a high level, the switching transistor DS is turned on, and current flows from the top of the motor to the bottom, passing through the switching transistor to GND. At this time, the voltage across the motor is positive (upper) and negative (lower), the diode D is in reverse cutoff state, and the buffer branch is not working.

[0121] Step 2: Switch Turn-off Stage like Figure 8 As shown, when the PWM signal goes low, the switch DS is turned off. Since the current in the motor inductor L cannot change abruptly, a reverse electromotive force is generated, forming a voltage polarity of - on top and + on the bottom. At this time, the inductor current is forward-biased through diode D, charging capacitor C. The voltage across capacitor C gradually rises, absorbing the stored energy in the inductor, thereby suppressing a sharp rise in the voltage across the switch DS.

[0122] Step 3: Energy Release Phase When capacitor C is charged to a certain voltage, it discharges through a parallel resistor R, converting the stored electrical energy into heat energy for stable dissipation. The resistance value of resistor R is optimized so that it can effectively limit the discharge current and prevent overheating under high-frequency switching conditions, while also ensuring that the capacitor voltage is released to a safe level before the next switching cycle.

[0123] Key design considerations: 1. The capacitance value of capacitor C needs to be selected comprehensively based on the equivalent inductance L of the motor, the switching frequency fsw, and the parasitic capacitance Coss of the switching transistor. It is usually in the nanofarad (nF) range to balance the absorption effect and the size. 2. The resistance value and power of resistor R should be designed based on the energy storage of capacitor C, switching frequency and maximum allowable temperature rise. It is recommended to use high frequency low inductance resistors, and multiple resistors can be connected in parallel to disperse thermal stress. 3. Diode D should be an ultra-fast recovery diode or a Schottky diode to reduce the impact of reverse recovery time on high-frequency switching.

[0124] Detailed Explanation of Key Design Considerations for Resonance Cancellation Circuits in Three Application Scenarios Combining the operating conditions and technical requirements of three major application scenarios—electric compressors for new energy vehicles, industrial servo systems, and brushless motors for drones—this paper outlines the key design points for each scenario, focusing on the topology layout, component selection, and integrated design of resonance cancellation circuits, and clarifies the relationship between design logic and scenario adaptability.

[0125] Example 1: GaN Controller for Electric Compressors in New Energy Vehicles 1. Core requirements for the scenario: high voltage (350V), high reliability, strong EMC compatibility, long life, and adaptable to a wide temperature range of -40℃ to 85℃ in vehicle environments.

[0126] Key design considerations for topology layout: Three-phase independent parallel layout 2. Design scheme: Connect the three sets of resonance elimination circuits in parallel to the upper and lower ends of the switching transistors of the A, B, and C phase bridge arms of the GaN three-phase inverter, respectively, and directly connect them to the drain and source terminals of the switching transistors.

[0127] 3. Design Logic: (1) The vehicle compressor motor is a three-phase permanent magnet synchronous motor. The three-phase windings work independently and the independent parallel layout can realize single-phase resonance suppression, avoid cross-phase resonance coupling amplification, and solve the resonance interference problem caused by the difference in the switching timing of multi-phase bridge arms.

[0128] (2) The circuit is connected in parallel across the two ends of the switching transistor. It is the core node for generating resonant energy (motor inductance + switching transistor Coss). It can absorb energy through the shortest path and reduce parasitic parameter loss during energy transmission.

[0129] 4. Scene adaptability: The vehicle environment is subject to severe vibration. The independently laid-out circuit modules do not interfere with each other. A fault in one phase circuit will not affect the normal operation of other phases, improving system redundancy and meeting the high reliability requirements of vehicle electronic equipment.

[0130] Key design considerations for integrated design: modularity and vibration-resistant packaging 5. Layout optimization: The resonance cancellation circuit and GaN switch are laid out on the same substrate, shortening the connection trace length (<5mm), reducing parasitic inductance, and improving the resonance suppression effect.

[0131] 6. Packaging Design: The encapsulation process is adopted, and epoxy resin is filled to enhance the vibration and impact resistance and meet the mechanical reliability test standards of automotive electronic equipment (such as GB / T 21563-2018).

[0132] Example 2: GaN Motor Controller for Industrial Servo Systems Core requirements for the scenario: high frequency (1MHz switching frequency), high precision (micron-level positioning), and high stability (24-hour continuous operation) to cope with the complex electromagnetic environment of industrial sites.

[0133] Key design considerations for topology layout: Dual resonance elimination layout using bridge arms and busbars. 1. Design scheme: The first group of circuits (bridge arm side) consists of 3 groups, which are connected in parallel to the two ends of the three-phase bridge arm switching transistors; the second group of circuits (bus side) consists of 1 group, which is connected in parallel between the positive and negative terminals of the DC bus, forming a "full-link resonance suppression" topology.

[0134] 2. Design Logic: (1) There are two sources of resonance in industrial servo systems: one is the LC resonance of the motor inductance and the Coss of the switching transistor on the bridge arm side, and the other is the LC resonance of the parasitic inductance of the line and the bus capacitance on the bus side. The two resonances will be coupled and amplified, and traditional single circuits cannot completely suppress them.

[0135] (2) The bridge arm side circuit is designed to suppress the resonance of the switching node, and the bus side circuit is designed to suppress the bus voltage oscillation. The dual layout achieves full coverage of the resonance source and avoids the resonance from propagating in the power circuit.

[0136] (3) Under 1MHz high-frequency switching, the current loop bandwidth is required to be ≥10kHz. The dual circuit can reduce current ripple, improve current sampling accuracy, and directly improve the position control accuracy of the servo system.

[0137] 3. Scene adaptability: Industrial sites have strong interference sources such as frequency converters and welding machines. The dual resonance elimination circuit can improve the system's anti-interference capability and avoid resonance runaway caused by external electromagnetic interference.

[0138] Key design considerations for integrated design: layered layout, signal and power isolation 4. Layered layout: The power circuit (main bus, bridge arm) and the control circuit (encoder signal, MCU drive) adopt a layered PCB design. The resonance cancellation circuit is placed on the power layer and a grounding isolation layer is added between it and the control layer to avoid high-frequency resonance interference with the control signal.

[0139] 5. Heat dissipation design: The bleed resistor is closely attached to the controller heat sink. For industrial servo systems that operate continuously for 24 hours, the heat dissipation design can control the resistor temperature rise to within 35℃, preventing parameter drift caused by high temperature.

[0140] Example 3: GaN Controller for Brushless Motors in UAVs Core requirements for the scenario: lightweight, miniaturized, low power consumption, adaptable to the vibration environment and long battery life requirements of drones, and the controller volume must be ≤10cm³.

[0141] Key design considerations for topology layout: Co-package close-to-device layout 1. Design scheme: Three sets of miniature resonance cancellation circuits are co-packaged with the integrated GaN module. The circuits are directly soldered to the drain and source pins of the GaN switch, and the connection trace length is <1mm.

[0142] 2. Design Logic: (1) The equivalent inductance of the brushless motor of the UAV is small (5μH~20μH), and the resonant frequency formed with the Coss of the switching transistor is as high as 10MHz or more. The parasitic inductance of the wiring of the traditional external circuit will become a new source of resonance. The close-to-device layout can eliminate the influence of parasitic inductance and achieve precise suppression of high-frequency resonance.

[0143] (2) The co-package design requires no additional PCB space, and the controller volume is reduced by 30% compared with the traditional solution, which meets the lightweight requirements of drones.

[0144] (3) The drone vibrates violently. Co-package avoids the risk of loose solder joints of external circuits and improves structural reliability.

[0145] 3. Scene adaptability: Close-proximity device layout shortens the energy transmission path, reduces switching losses by 25%, directly improves controller energy efficiency, and extends drone flight time.

[0146] Key design considerations for integrated design: leadless connection and high-temperature resistant packaging.

[0147] 4. Leadless connection: The resonance cancellation circuit and GaN switch are directly soldered to the pads, eliminating the traditional wire connection and further reducing parasitic inductance and size.

[0148] 5. High-temperature resistant packaging: High-temperature ceramic packaging is used. The controller temperature rise can reach 60℃ during drone flight. High-temperature packaging ensures that the component parameters are stable within a wide temperature range and there is no risk of failure.

[0149] In one specific embodiment, it is applied to a GaN motor controller with a switching frequency fsw = 500kHz: The equivalent inductance of the motor is L = 50 μH; The parasitic capacitance of the switching transistor, Coss, is 100pF. Select an absorption capacitor C = 2.2nF (high-frequency ceramic capacitor); Discharge resistor R = 10Ω (power not less than 1W, low inductance type); Diode D is a Schottky diode with a reverse recovery time trr < 10 ns.

[0150] The measured results show that the peak voltage of the switching transistor turned off decreased from 120V to below 80V, the temperature rise of the resistor was less than 40°C under full load conditions, and the system efficiency decreased by no more than 0.5%.

[0151] 1. Design selection parameter value range (refer to Table 1 below). These parameters are the recommended ranges for component selection and must match the high-frequency operating requirements of 500kHz switching frequency.

[0152] Table 1

[0153] 2. Measured performance parameter range (refer to Table 2 below). These parameters represent the measured fluctuation range after the absorption circuit is put into use, reflecting the stability of the solution.

[0154] Table 2

[0155] In an optional embodiment, (1) multiple capacitors are connected in parallel to increase the absorption capacity; (2) a resistor with a positive temperature coefficient (PTC) is used instead of a fixed resistor to improve reliability at high temperatures; and (3) a small capacitor is connected in parallel across the diode D to further suppress oscillations caused by reverse recovery.

[0156] Beneficial effects of the technical solution of this invention (1) Effectively suppress voltage spikes: By absorbing the energy stored in the inductor in real time through capacitor C, the voltage stress at the turn-off time of the switching transistor is significantly reduced, avoiding overvoltage breakdown; (2) Improve resistor reliability: By reasonably designing RC parameters, control the discharge current and power consumption to avoid overheating and damage to the resistor at high frequencies; (3) Simple structure and easy integration: Only a few passive components are required, making it suitable for high-density motor controller design; (4) Compatible with high-frequency applications: The circuit has a fast response speed and is suitable for GaN switching frequencies in the hundreds of kHz to MHz range; (5) Extend system life: reduce electrical and thermal stress of switching transistors and improve overall system reliability.

[0157] Those skilled in the art will understand that all or part of the processes of the methods described in the above embodiments can be implemented by a computer program instructing related hardware, and the program can be stored in a computer-readable storage medium. The computer-readable storage medium may be a disk, optical disk, read-only memory, or random access memory, etc.

[0158] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. A gallium nitride motor controller, characterized in that, include: Electric motor; A power control device, connected in series with the motor, is used to control the power supply to or from the motor, and includes a gallium nitride switching transistor, wherein the gallium nitride switching transistor has parasitic capacitance; A resonance cancellation circuit, connected to the power control device, includes a freewheeling diode, a snubber capacitor, and a bleeder resistor. The snubber capacitor and the bleeder resistor are connected in parallel. The freewheeling diode, the snubber capacitor connected in parallel, and the bleeder resistor are connected in series. When the gallium nitride switch is in the off phase, the inductor current of the motor is forward-biased through the freewheeling diode, charging the absorption capacitor and causing the voltage of the absorption capacitor to gradually increase. When the gallium nitride switch is in the energy dissipation stage and the absorption capacitor rises to a predetermined voltage, it discharges through the discharge resistor, converting the stored electrical energy into heat energy for stable dissipation.

2. The gallium nitride motor controller according to claim 1, characterized in that, The absorption capacitor is used to absorb the resonant energy of the motor winding inductance and the parasitic capacitance to suppress voltage spikes, wherein... The capacitance value of the absorption capacitor is selected based on the equivalent inductance of the motor, the switching frequency of the gallium nitride switch, and the parasitic capacitance.

3. The gallium nitride motor controller according to claim 1, characterized in that, The discharge resistor is used to control the discharge rate of the absorption capacitor to release the resonant energy stored in the absorption capacitor, wherein, The resistance and power of the bleed resistor are selected based on the resonant energy stored in the absorption capacitor, the switching frequency of the gallium nitride switch, and the maximum allowable temperature rise.

4. The gallium nitride motor controller according to claim 1, characterized in that, The freewheeling diode is used to provide a freewheeling path for the inductor current when the gallium nitride switch is turned off. The freewheeling diode is selected as an ultrafast recovery diode or a Schottky diode to reduce the impact of the reverse recovery time on the gallium nitride switch.

5. The gallium nitride motor controller according to claim 1, characterized in that, The motor includes a DC motor, an electric compressor permanent magnet synchronous motor, a servo motor, or a drone brushless motor.

6. The gallium nitride motor controller according to claim 5, characterized in that, When the motor is a DC motor, the resonance cancellation circuit is connected in parallel between the positive and negative terminals of the DC motor.

7. The gallium nitride motor controller according to claim 5, characterized in that, When the motor is the permanent magnet synchronous motor of the electric compressor, the gallium nitride motor controller includes a first gallium nitride three-phase inverter for the electric compressor of the new energy vehicle, and the resonance cancellation circuit is a first resonance cancellation circuit, wherein... The first gallium nitride three-phase inverter is used to convert the DC voltage provided by the vehicle high-voltage battery into a three-phase AC voltage and supply it to the permanent magnet synchronous motor of the electric compressor. The first resonance cancellation circuit is connected in parallel across each gallium nitride switch in the upper and lower gallium nitride switches of each phase arm of the first gallium nitride three-phase inverter.

8. The gallium nitride motor controller according to claim 5, characterized in that, When the motor is the servo motor, the gallium nitride motor controller includes a three-phase power frequency rectifier and filter module, a second gallium nitride three-phase inverter, and an enhanced resonance cancellation circuit, wherein the resonance cancellation circuit is a second resonance cancellation circuit and an enhanced resonance cancellation circuit. The three-phase power frequency rectifier and filter module is used to rectify the three-phase power frequency AC voltage to provide DC voltage through the positive and negative terminals of the DC bus; The second gallium nitride three-phase inverter is used to convert DC voltage into three-phase AC voltage and supply it to the servo motor; The second resonance cancellation circuit is connected in parallel across each gallium nitride switch in the upper and lower gallium nitride switches of each phase arm of the second gallium nitride three-phase inverter; The enhanced resonance cancellation circuit is connected in parallel between the positive and negative terminals of the DC bus.

9. The gallium nitride motor controller according to claim 5, characterized in that, When the motor is the brushless motor of the UAV, the gallium nitride motor controller includes a third gallium nitride three-phase inverter and the resonance cancellation circuit is a third resonance cancellation circuit, wherein... The third gallium nitride three-phase inverter is used to convert the drone's lithium battery voltage into a three-phase AC voltage and supply the three-phase AC voltage to the drone's brushless motor; The third resonance cancellation circuit is co-packaged with the third gallium nitride three-phase inverter and connected in parallel between the drain and source of each phase gallium nitride switch in the third gallium nitride three-phase inverter.

10. A resonance cancellation method for a gallium nitride motor controller according to any one of claims 1 to 9, characterized in that, include: The conduction control signal is provided to the gate of the gallium nitride switch in the power control device, so that the gallium nitride switch is turned on, the motor is powered on, the freewheeling diode is in the off state, and the resonance cancellation circuit does not work. A shutdown control signal is provided to the gate of the gallium nitride switch, which switches from the conduction stage to the shutdown stage, controlling the motor to turn off. The inductor current of the motor is forward-biased through the freewheeling diode, charging the absorption capacitor and causing the voltage of the absorption capacitor to gradually increase. When the absorption capacitor rises to a predetermined voltage, the gallium nitride switch switches from the turn-off stage to the energy discharge stage, and discharges through the discharge resistor to convert the stored electrical energy into heat energy for stable dissipation.

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