Electrolytic capacitor-free motor controller with surge protection and ECM motor

Abstract

The utility model discloses an electrolytic capacitor-free motor controller with surge protection and an ECM motor, comprising an AC side surge protection circuit, a three-phase rectifier BG1, a DC side surge protection circuit, a thin film capacitor C0 and an inverter circuit, the DC side surge protection circuit comprises an inductor L2, a piezoresistor VAR7 and a discharge tube TSS1, a direct-current output end P of the three-phase rectifier BG1 is connected with one end of the inductor L2, the other end of the inductor L2 is connected with one end of the thin-film capacitor C0, the other end of the thin-film capacitor C0 is connected with the ground GND, the piezoresistor VAR7 and the discharge tube TSS1 are connected in series, and then the two ends of the piezoresistor VAR7 and the two ends of the discharge tube TSS1 are connected with the direct-current output end P of the three-phase rectifier BG1 and the ground GND respectively. Pulse current in surge can be effectively absorbed, and EMI parameters are improved; and product reliability is good.

Description

Technical fields:

[0001] This utility model relates to a capacitor-free motor controller with surge protection and an ECM motor. Background technology:

[0002] As we all know, electronic products frequently encounter unexpected voltage transients and surges during use, which can damage the products and even endanger personal safety. The causes of surges are multifaceted, including lightning strikes, power grid overvoltage, switch arcing, and equipment start-ups, shutdowns, and malfunctions within the power supply system. To improve the reliability of electronic products and ensure human safety, surge protection measures must be implemented.

[0003] The current ECM motor structure includes a motor body and a motor controller. The motor body includes a stator assembly and a rotor assembly. The motor controller includes a surge protection circuit, a rectifier filter circuit, a DC bus electrolytic capacitor C, and a motor control drive module. The motor control drive module includes a microprocessor (MCU), an inverter circuit, and a rotor position detection circuit (or back EMF detection circuit), as seen in patent number CN202420672491, entitled "A Utility Model Patent for a Motor Controller with a Novel Surge Protection Circuit and an ECM Motor." In this patent, a surge protection circuit is present on the AC side, and the surge absorption effect of the electrolytic capacitor C is utilized on the DC side, which basically provides surge protection and meets customer requirements.

[0004] Traditional motor controllers use electrolytic capacitors as the DC-side bus capacitors, with capacitance values ​​exceeding several hundred microfarads. While these capacitors can stabilize the bus voltage, they suffer from short lifespan, large size, and high cost. Replacing electrolytic capacitors with film capacitors as the DC-side bus capacitors addresses these inherent drawbacks. However, film capacitors, with their extremely small capacitance values ​​(approximately tens of microhenries), offer very poor surge current and voltage protection on the DC side, making them prone to overvoltage faults and even damage to power devices. This is particularly challenging given the current domestic and international requirements to upgrade surge protection to 6kV levels. Summary of the Invention:

[0005] The purpose of this invention is to provide a capacitor-free motor controller and ECM motor with surge protection, which solves the technical problems of existing capacitor-free motor controllers that use film capacitors as DC-side bus capacitors, resulting in very poor DC-side surge current and voltage protection capabilities, easy overvoltage faults, and even burnout of power devices.

[0006] The objective of this utility model is achieved through the following technical solution:

[0007] A surge-protected, capacitor-free motor controller includes an AC-side surge protection circuit, a three-phase rectifier BG1, a DC-side surge protection circuit, a film capacitor C0, and an inverter circuit. The three-phase AC input terminals R, S, and T charge the film capacitor C0 after passing through the AC-side surge protection circuit, the three-phase rectifier BG1, and the DC-side surge protection circuit. The two ends of the film capacitor C0 form a DC bus voltage Vdc, providing power to the inverter circuit. The DC-side surge protection circuit includes an inductor L2, a varistor VAR7, and a discharge tube TSS1. The DC output terminal P of the three-phase rectifier BG1 is connected to one end of the inductor L2, and the other end of the inductor L2 is connected to one end of the film capacitor C0. The other end of the film capacitor C0 is connected to ground GND. The varistor VAR7 and the discharge tube TSS1 are connected in series, with their two ends connected to the DC output terminal P of the three-phase rectifier BG1 and ground GND, respectively.

[0008] Preferably, a resistor R1 is connected in parallel across the varistor VAR7, and a resistor R2 is connected in parallel across the discharge tube TSS1.

[0009] Preferably, the discharge tube TSS1 is a semiconductor discharge tube.

[0010] Preferably, the AC surge protection circuit includes varistors VAR1, VAR2, VAR3, VAR4, VAR5, and VAR6, gas discharge tubes SPG1, SPG2, SPG3, and SPG4, capacitors C1, C2, and C3, and a common-mode inductor L1. The three-phase AC input terminals R, S, and T are connected to the A, B, and C three-phase power supply lines, wherein:

[0011] One end of varistor VAR1 is connected to the power supply line of phase A, and the other end of varistor VAR1 is connected to the common point G. One end of varistor VAR2 is connected to the power supply line of phase B, and the other end of varistor VAR2 is connected to the common point G. One end of varistor VAR3 is connected to the power supply line of phase C, and the other end of varistor VAR3 is connected to the common point G. The two ends of discharge tube SPG1 are connected to the common point G and the grounding point PE, respectively.

[0012] After the varistor VAR4 is connected in series with the gas discharge tube SPG2, its two ends are connected to the A-phase power supply line and the C-phase power supply line respectively; after the varistor VAR5 is connected in series with the gas discharge tube SPG3, its two ends are connected to the A-phase power supply line and the B-phase power supply line respectively; after the varistor VAR6 is connected in series with the gas discharge tube SPG4, its two ends are connected to the B-phase power supply line and the C-phase power supply line respectively.

[0013] One end of capacitor C1 is connected to the A-phase power supply line, and the other end is connected to the common point H; one end of capacitor C2 is connected to the B-phase power supply line, and the other end is connected to the common point H; one end of capacitor C3 is connected to the C-phase power supply line, and the other end is connected to the common point H. The ends of the A-phase, B-phase, and C-phase power supply lines are connected to one side of the common-mode inductor L1, and the other side of the common-mode inductor L1 is connected to the input terminal of the three-phase rectifier BG1.

[0014] Preferably, fuses F1, F2, and F3 are respectively installed on the A, B, and C three-phase power supply lines near the three-phase AC input terminals R, S, and T.

[0015] Preferably, the motor controller further includes a microprocessor and a back EMF detection circuit. The back EMF detection circuit acquires the parameters of motor operation and sends them to the microprocessor. The output of the microprocessor controls the operation of the inverter circuit.

[0016] An ECM motor includes a motor body and a motor controller. The motor body includes a stator assembly and a rotor assembly. The motor controller is characterized by employing the electrolytic capacitor-free motor controller with surge protection as described above.

[0017] Compared with the prior art, this utility model has the following advantages:

[0018] Effect 1: The DC-side surge protection circuit of this utility model includes an inductor L2, a varistor VAR7, and a discharge tube TSS1. This combination has a good surge suppression effect, effectively absorbing the pulse current in the surge and improving EMI parameters. In the series branch composed of varistor VAR7 and discharge tube TSS1, the discharge tube acts as a switch: when there is no surge voltage, the discharge tube does not conduct, which can isolate the varistor from the system, so that there is almost no leakage current in the varistor, thus extending the life of the varistor. During the surge voltage, due to the small parasitic capacitance of the discharge tube, the voltage across the discharge tube is higher. At this time, the discharge tube conducts first, and then the surge voltage is applied to the varistor. The resistance of the varistor drops rapidly and conducts, the current increases, and the impact energy is discharged. After a surge, based on the typical volt-ampere characteristic curve of the discharge tube, when the voltage drops below the operating voltage of the varistor, the discharge tube enters the arc discharge region. The resistance of the varistor rises rapidly, cutting off the voltage required for arc discharge and reducing the impact of the discharge tube's follow current on turn-off. This series-connected composite component (varistor in series with discharge tube) allows for the selection of varistors with lower clamping voltages. Because this series connection provides a lower clamping voltage than a single varistor, it means that varistors with lower nominal voltages can be used, thus improving the reliability of surge protection. The presence of inductor L2 improves the power factor of the motor controller.

[0019] Effect 2: The discharge tube TSS1 has been changed from a traditional gas discharge tube to a semiconductor discharge tube. Gas discharge tubes have a large dispersion, while semiconductor discharge tubes are more precise. In other words, semiconductor discharge tubes result in lower residual voltage and longer lifespan, further improving the reliability of the controller.

[0020] Effect 3: By connecting resistor R1 in parallel across the varistor VAR7 and resistor R2 in parallel across the discharge tube TSS1, the DC-side surge absorption increases impedance matching, preventing the circuit from being mis-conducted and damaging the varistor under AC components, thus increasing the reliability of the circuit.

[0021] Effect 4: This utility model is compatible with various power grids because it has both AC-side surge protection circuits and DC-side surge protection circuits. Attached image description:

[0022] Figure 1 This is a circuit block diagram of the motor controller according to Embodiment 1 of this utility model;

[0023] Figure 2 yes Figure 1 The corresponding part of the circuit diagram;

[0024] Figure 3 yes Figure 1 The corresponding other part of the circuit diagram;

[0025] Figure 4 yes Figure 1 The circuit diagram corresponding to the AC side surge protection circuit;

[0026] Figure 5 This is a perspective view of the ECM motor according to Embodiment 2 of this utility model;

[0027] Figure 6 This is a structural cross-sectional view of the ECM motor according to Embodiment 2 of this utility model. Detailed implementation method:

[0028] The present invention will now be described in further detail through specific embodiments and in conjunction with the accompanying drawings.

[0029] Example 1:

[0030] like Figures 1 to 4As shown, this embodiment provides a surge-protected electrolytic capacitor-free motor controller, including an AC-side surge protection circuit, a three-phase rectifier BG1, a DC-side surge protection circuit, a thin-film capacitor C0, and an inverter circuit. The three-phase AC input terminals R, S, and T charge the thin-film capacitor C0 after passing through the AC-side surge protection circuit, the three-phase rectifier BG1, and the DC-side surge protection circuit. The two ends of the thin-film capacitor C0 form a DC bus voltage Vdc to provide power to the inverter circuit. The DC-side surge protection circuit includes an inductor L2, a varistor VAR7, and a discharge tube TSS1. The DC output terminal P of the three-phase rectifier BG1 is connected to one end of the inductor L2, and the other end of the inductor L2 is connected to one end of the thin-film capacitor C0. The other end of the thin-film capacitor C0 is connected to ground GND. The varistor VAR7 and the discharge tube TSS1 are connected in series and their two ends are respectively connected to the DC output terminal P of the three-phase rectifier BG1 and ground GND.

[0031] This invention relates to a DC-side surge protection circuit comprising an inductor L2, a varistor VAR7, and a discharge tube TSS1. This combination provides good surge suppression, effectively absorbing pulse currents during surges and improving EMI parameters. In the series branch consisting of the varistor VAR7 and the discharge tube TSS1, the discharge tube acts as a switch: when there is no surge voltage, the discharge tube is not conducting, isolating the varistor from the system and ensuring almost no leakage current in the varistor, thus extending its lifespan. During a surge voltage event, the small parasitic capacitance of the discharge tube allows for a higher voltage drop across it, causing it to conduct first. Then, the surge voltage is applied to the varistor, causing its resistance to drop rapidly, increasing the current and dissipating the impact energy. After the surge, based on the typical volt-ampere characteristic curve of the discharge tube, when the voltage drops below the varistor's operating voltage, the discharge tube enters the arc discharge region. The varistor's resistance rises rapidly, cutting off the voltage required for arc discharge and reducing the impact of the discharge tube's follow current on turn-off. This series-connected composite component (varistor in series with discharge tube) allows for the selection of varistors with lower clamping voltages. Because this series connection provides a lower clamping voltage than a single varistor, it means that varistors with lower nominal voltages can be used, thus improving the reliability of surge protection. The presence of inductor L2 improves the power factor of the motor controller.

[0032] Preferably, a resistor R1 is connected in parallel across the varistor VAR7, and a resistor R2 is connected in parallel across the discharge tube TSS1. DC-side surge absorption increases impedance matching, preventing accidental circuit conduction and damage to the varistor under AC components, thus increasing circuit reliability.

[0033] Preferably, the discharge tube TSS1 is a semiconductor discharge tube. The discharge tube TSS1 is changed from a traditional gas discharge tube to a semiconductor discharge tube. Gas discharge tubes have a large dispersion, while semiconductor discharge tubes are more precise. That is, semiconductor discharge tubes result in lower residual voltage and longer lifespan, further improving the reliability of the controller.

[0034] Preferably, the AC surge protection circuit includes varistors VAR1, VAR2, VAR3, VAR4, VAR5, and VAR6, gas discharge tubes SPG1, SPG2, SPG3, and SPG4, capacitors C1, C2, and C3, and a common-mode inductor L1. The three-phase AC input terminals R, S, and T are connected to the A, B, and C three-phase power supply lines, wherein:

[0035] One end of varistor VAR1 is connected to the A-phase power supply line, and the other end is connected to the common point G. One end of varistor VAR2 is connected to the B-phase power supply line, and the other end is connected to the common point G. One end of varistor VAR3 is connected to the C-phase power supply line, and the other end is connected to the common point G. The two ends of discharge tube SPG1 are connected to the common point G and the grounding point PE, respectively. This connection serves as common-mode surge protection. The discharge tube acts as a switch: when there is no surge voltage, the discharge tube is not conducting, isolating the varistor from the system and ensuring almost no leakage current in the varistor, thus extending its lifespan. During a surge voltage, due to the small parasitic capacitance of the discharge tube, the voltage across the discharge tube is higher. At this time, the discharge tube conducts first, and then the surge voltage is applied to the varistor, causing the varistor resistance to drop rapidly and conduct, increasing the current and dissipating the impact energy.

[0036] Varistor VAR4 is connected in series with gas discharge tube SPG2, and its two ends are connected to the A-phase power supply line and the C-phase power supply line respectively; varistor VAR5 is connected in series with gas discharge tube SPG3, and its two ends are connected to the A-phase power supply line and the B-phase power supply line respectively; varistor VAR6 is connected in series with gas discharge tube SPG4, and its two ends are connected to the B-phase power supply line and the C-phase power supply line respectively. This connection serves as differential mode surge protection. In this series branch, the discharge tube acts as a switch: when there is no surge voltage, the discharge tube is not conducting, isolating the varistor from the system and ensuring almost no leakage current in the varistor, thus extending its lifespan; during a surge voltage, due to the small parasitic capacitance of the discharge tube, the voltage across the discharge tube is higher, causing the discharge tube to conduct first, and then the surge voltage is applied to the varistor, causing the varistor resistance to drop rapidly and conduct, increasing the current and dissipating the impact energy. After the surge, based on the typical volt-ampere characteristic curve of the discharge tube, when the voltage is lower than the operating voltage of the varistor, the discharge tube enters the arc discharge region, and the resistance of the varistor rises rapidly, cutting off the voltage required for arc discharge, which can reduce the impact of the discharge tube's follow current on the turn-off.

[0037] One end of capacitor C1 is connected to the A-phase power supply line, and the other end is connected to the common point H; one end of capacitor C2 is connected to the B-phase power supply line, and the other end is connected to the common point H; one end of capacitor C3 is connected to the C-phase power supply line, and the other end is connected to the common point H. The ends of the A-phase, B-phase, and C-phase power supply lines are connected to one side of the common-mode inductor L1, and the other side of the common-mode inductor L1 is connected to the input terminal of the three-phase rectifier BG1.

[0038] To adapt to various power grids, such as the delta-connected grounding point (PE) in some US power grids, the AC surge protection circuit of this invention requires common-mode protection varistor parameters that are compatible with the grid parameters. Generally, varistor parameters with higher clamping ratings are selected. In this series branch composite (varistor series discharge tube), a varistor with a lower clamping voltage can be chosen. Since this series branch provides a lower clamping voltage than a single varistor, it means that a varistor with a lower nominal voltage can be used, thereby improving the reliability of surge protection.

[0039] Preferably, fuses F1, F2, and F3 are respectively installed on the A, B, and C three-phase power supply lines near the three-phase AC input terminals R, S, and T.

[0040] Preferably, the motor controller of this utility model further includes a microprocessor and a back EMF detection circuit. The back EMF detection circuit acquires the parameters of motor operation and sends them to the microprocessor. The output of the microprocessor controls the operation of the inverter circuit.

[0041] Example 2:

[0042] like Figures 1 to 6 As shown, the ECM motor provided in this embodiment includes a motor body 100 and a motor controller 200. The motor body 100 includes a permanent magnet rotor assembly 12, a stator assembly 11, and a housing assembly 13. The motor controller 200 includes a control box 21 and a control circuit board 22 installed inside the control box 21. The control circuit board 22 integrates an AC side surge protection circuit, a three-phase rectifier BG1, a DC side surge protection circuit, a thin film capacitor C0, an inverter circuit, a microprocessor, and a back EMF detection circuit. The back EMF detection circuit acquires the phase current signal and sends it to the microprocessor. The microprocessor outputs several PWM signals to control the operation of the inverter circuit. The output terminal of the inverter circuit is connected to the coil winding inside the stator assembly 11. The characteristic feature is that the motor controller 200 adopts a motor controller with a novel surge protection circuit as described in Embodiment 1.

[0043] This utility model's ECM motor has good surge absorption effect and superior protection performance. It can meet the insulation withstand voltage requirements of the product, suppress the pulse current spikes generated during the discharge tube conduction process, improve EMI parameters, and reduce malfunctions.

[0044] The above embodiments are preferred embodiments of the present utility model, but the embodiments of the present utility model are not limited thereto. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present utility model are equivalent substitutions and are included within the protection scope of the present utility model.

Claims

1. A surge-protected, capacitor-free motor controller, comprising an AC-side surge protection circuit, a three-phase rectifier BG1, a DC-side surge protection circuit, a film capacitor C0, and an inverter circuit. The three-phase AC input terminals R, S, and T charge the film capacitor C0 after passing through the AC-side surge protection circuit, the three-phase rectifier BG1, and the DC-side surge protection circuit. The two ends of the film capacitor C0 form a DC bus voltage Vdc, which provides power to the inverter circuit. The controller is characterized by: The DC-side surge protection circuit includes an inductor L2, a varistor VAR7, and a discharge tube TSS1. The DC output terminal P of the three-phase rectifier BG1 is connected to one end of the inductor L2, and the other end of the inductor L2 is connected to one end of the film capacitor C0. The other end of the film capacitor C0 is connected to ground GND. The varistor VAR7 and the discharge tube TSS1 are connected in series and their two ends are connected to the DC output terminal P of the three-phase rectifier BG1 and ground GND, respectively.

2. A motor controller without electrolytic capacitor with surge protection according to claim 1 characterized by: A resistor R1 is connected in parallel across the varistor VAR7, and a resistor R2 is connected in parallel across the discharge tube TSS1.

3. A motor controller without electrolytic capacitor with surge protection according to claim 1 or 2, characterized in that: The discharge tube TSS1 is a semiconductor discharge tube.

4. A motor controller without electrolytic capacitor with surge protection according to claim 1 characterized by: The AC surge protection circuit includes varistors VAR1, VAR2, VAR3, VAR4, VAR5, and VAR6, gas discharge tubes SPG1, SPG2, SPG3, and SPG4, capacitors C1, C2, and C3, and a common-mode inductor L1. The three-phase AC input terminals R, S, and T are connected to the A, B, and C phase power supply lines. One end of varistor VAR1 is connected to the power supply line of phase A, and the other end of varistor VAR1 is connected to the common point G. One end of varistor VAR2 is connected to the power supply line of phase B, and the other end of varistor VAR2 is connected to the common point G. One end of varistor VAR3 is connected to the power supply line of phase C, and the other end of varistor VAR3 is connected to the common point G. The two ends of discharge tube SPG1 are connected to the common point G and the grounding point PE, respectively. After the varistor VAR4 is connected in series with the gas discharge tube SPG2, its two ends are connected to the A-phase power supply line and the C-phase power supply line respectively; after the varistor VAR5 is connected in series with the gas discharge tube SPG3, its two ends are connected to the A-phase power supply line and the B-phase power supply line respectively; after the varistor VAR6 is connected in series with the gas discharge tube SPG4, its two ends are connected to the B-phase power supply line and the C-phase power supply line respectively. One end of capacitor C1 is connected to the A-phase power supply line, and the other end is connected to the common point H; one end of capacitor C2 is connected to the B-phase power supply line, and the other end is connected to the common point H; one end of capacitor C3 is connected to the C-phase power supply line, and the other end is connected to the common point H. The ends of the A-phase, B-phase, and C-phase power supply lines are connected to one side of the common-mode inductor L1, and the other side of the common-mode inductor L1 is connected to the input terminal of the three-phase rectifier BG1.

5. The motor controller with surge protection and without electrolytic capacitor according to claim 4, characterized in that: Fuse F1, fuse F2, and fuse F3 are respectively installed on the A, B, and C three-phase power supply lines near the three-phase AC input terminals R, S, and T.

6. A motor controller with surge protection and without electrolytic capacitor according to claim 5, characterized in that: It also includes a microprocessor and a back EMF detection circuit. The back EMF detection circuit acquires the parameters of the motor operation and sends them to the microprocessor. The output of the microprocessor controls the operation of the inverter circuit.

7. An ECM electric machine comprising an electric machine body and an electric machine controller, the electric machine body comprising a stator assembly and a rotor assembly, characterized by: The motor controller adopts the electrolytic capacitor-free motor controller with surge protection as described in any one of claims 1 to 6.

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