30results about How to "Eliminate common mode voltage" patented technology

A double reference wave modulation scheme for filterless power amplifiers is disclosed for reducing EMI and common mode voltages. In the filterless power amplifier, differential outputs for driving load impedance are feedback and corrected based on input audio signals. Reference wave generators generate reference waves. A control logic results pulses in the pair of differential outputs in response to a clock signal or a reference voltage and a cross relationship between the input audio signal and the first and second reference waves. Pulses of one of the differential outputs are not overlapped with pulses of the other of the differential outputs for eliminating common mode noises of the power amplifier.

The invention discloses a motor driving shaft grounding device. A conductive sealing ring (12) sleeves the driving shaft (20) in a sealing mode and rotates along with the driving shaft; the conductivesealing ring forms a first sealing surface along the side surface, axially deviating from the motor, of the driving shaft; the first sealing surface is provided with multiple first annular parts (122) arranged radially; one side of the first sealing surface of the conductive sealing ring is provided with a sleeving part (124); a conductive fixing ring (14) is fixed on a motor housing (30) and sleeves the sleeving part; a second sealing surface is formed on the side surface, facing the first sealing surface, of the conductive fixing ring; the second sealing surface is provided with multiple second annular parts (122) arranged radially; shapes of the second annular parts and the first annular parts are complementary; a conductive connection part (162) of a grounding element (16) is connected with the conductive sealing ring or the conductive fixing ring, and the conductive contact part (164) of the grounding element continuously contacts the other one in the conductive sealing ring or the conductive fixing ring. The grounding device can eliminate common mode current. The invention also provides a motor.

A single-phase three-level inverter includes an input capacitor (Cdc), six power switches (S1, S2, S3, S4, S5, S6), two free-wheeling diodes (D7, D8) and a single-phase output filter (F). The switching operation is performed by the cooperation of the six power switches and the free-wheeling diodes, so that when the output voltage from the inverter is zero level, the output AC side and the input DC side of the inverter are in a decoupled state, which insures that the common-mode voltage is maintained at a constant while the output voltage from the inverter is performed with three levels, so as to completely eliminate the common-mode current.

The invention discloses a method and system for suppressing the common mode noise of an asymmetrical six-phase AC motor. Phase, so that the two sets of three-phase inverters driving the asymmetric six-phase AC motor output common-mode voltages with opposite amplitudes, so as to eliminate the total common-mode voltage input from the inverter to the asymmetric six-phase AC motor, thereby suppressing the non-symmetrical six-phase AC motor. Common mode noise generated by symmetrical six-phase motors; at the same time, the control method and system of the present invention do not require additional hardware, and can be realized only by improving software algorithms, have strong versatility, can protect motor bearings, and improve system reliability.

The invention discloses a three-level zero-common-mode voltage modulation method based on DSP and CPLD. By distributing and adjusting the PWM pulse wave modulated by two levels, a set of intermediate voltages effective for three-level inverters is generated. In the vector switch state, the combination of three-level vectors is used to directly control the three-level main circuit, so as to achieve the purpose of outputting the common mode voltage to zero. The modulation method of the present invention is simple and easy to implement, does not require any external hardware circuit, is suitable for any modulation wave, outputs a common mode voltage of zero, eliminates the leakage current caused by the common mode voltage and leakage capacitance, and fundamentally eliminates the common mode voltage .

The invention provides a three-phase space vector rapid modulation method in a two-dimensional coordinate system, which belongs to the technical field of power electronic modulation. This method transforms the traditional three-phase two-dimensional coordinate system into a new two-dimensional rectangular coordinate system, and obtains the remaining two vectors of the modulation triangle by directly checking the vector closest to the origin, which has strong scalability. In addition, this method can provide several controllable factors, and the factor N can be used as an optimization target to weaken the common-mode voltage and select redundant vectors for voltage equalization; the controllable switching sequence produced can ensure the smooth transition of vectors in the modulation triangle and between modulation triangles To reduce the overall switching frequency of the system to reduce switching loss and optimize harmonic performance; adjustable zero-vector duty cycle can also optimize harmonic performance, synthesize a more ideal flux linkage circle to output high-quality sine waves and ensure the same voltage as the factor N balanced. The function of this method reflects its superior application value and good application prospect.

A fault-tolerant modulation method for a double-terminal cascaded five-level inverter with a common bus. The stator winding of the motor is opened, and the two ends of the stator winding are powered by two identical inverters, and the two inverters share a The DC bus is set to form a common bus double-ended cascaded five-level topology; in order to ensure that the reference voltage vector track is a circle, when a short-circuit fault occurs in the switching device, the maximum output voltage of the inverter will drop to half of the original, and only the inner six The polygon can use the switch state to synthesize the reference voltage vector, and use the rotation and per unit of the coordinate system to effectively simplify the five-level modulation method and reduce the hardware requirements of the system control; use the balance factor to ensure the fault-tolerant control, and realize the midpoint potential balance. The present invention is based on the high fault-tolerant characteristics of the double-ended cascaded five-level inverter. When the switching device fails, the fault-tolerant operation of the inverter is realized by reselecting the voltage vector; an optimization method is proposed for the double-ended cascaded system The 60° modulation method.

The invention relates to a permanent magnet surface flow field sensor and a sensor array. The sensor includes: an electrode, a conductive base, an insulating layer, a base plate and a magnet; the electrode is fixed on the conductive base, the conductive base is fixed on the first part of the base plate, and the insulating layer is fixed on the base plate The second part of the magnet is attached to the bottom surface of the substrate. The present invention can reduce the size of the underwater speed odometer and realize surface mounting.

The invention relates to a low-frequency fully differential Gm-C filter applied to ECG signal acquisition. And the filter comprises a transconductance unit, a capacitor C1, a capacitor C2, a capacitorC3 and a capacitor C4, and the transconductance unit comprises a fully differential transconductance unit Gm1, a fully differential transconductance unit Gm2, a fully differential transconductance unit Gm3, a fully differential transconductance unit Gm4 and a fully differential transconductance unit Gm5. The improved source electrode negative feedback circuit is adopted, common-mode voltage on aresistor is effectively eliminated, the upper limit of input common-mode voltage is prevented from being reduced, and it is convenient to achieve that the output common-mode voltage is equal to the input common-mode voltage; The pseudo full-differential circuit based on the series-parallel current mirror is adopted, and a common-mode feedback circuit of a traditional full-differential circuit is prevented from being used for determining the output common-mode voltage, so that the complexity of circuit design is reduced, and the power consumption is reduced.

The invention provides a modulation method of a multi-level inverter without common-mode voltage, belonging to the technical field of multi-level inverter modulation. The modulation method comprises the steps that modulating wave is decomposed, and every two phases of the decomposed modulating wave are subtracted from each other to obtain original modulating wave; the decomposed modulating wave issubjected to one-dimensional space vector modulation to obtain the action vector for synthesizing the modulating wave and the corresponding action time of the vector; by being compared with the sawtooth carrier, the vector with small modulus in one carrier period of the positive half period is output first, and the vector with large modulus in the negative half period is output first to obtain intermediate PWM signals; a three-phase PWM signal is obtained by subtracting every two phases of the intermediate PWM signals; and redundant vectors are selected according to the actual needs of different topologies. The modulation method eliminates the common mode voltage, eliminates the influence of the leakage current on the grid-connected current, and improves the waveform quality. Compared with the traditional SVPWM modulation strategy, two-dimensional simplification is changed to one-dimensional simplification, sector judgment and vector action time are simplified, without trigonometric function operation, and the computational effort is small. The method has high versatility for different inverter topologies.

The invention discloses an AC and DC power supply system, which includes: installing a grounding device between the AC system and the converter system, and the grounding device is also connected to the neutral line and the earth, so as to provide the neutral line and the grounding point for the converter system, The wiring mode of the converter system is not limited to the three-phase three-wire system; the common mode voltage elimination circuit is connected to the AC side and the DC side of the converter system, and the common mode voltage elimination circuit is not limited to suppressing the common voltage between the AC and DC sides of the converter system. mode voltage, and at the same time induce the corresponding proportion of reverse common-mode voltage, and connect it in series to the DC bus and ground loop, so as to realize the elimination of the common-mode voltage of the converter system to the ground.

The invention discloses a modulation method and a system for suppressing a common-mode voltage by an MMC suitable for an even number of sub-modules, and belongs to the field of electric power. Including: converting the three-phase reference voltage analog linear operation into three reference line voltage analogs injected into the zero-sequence component; for MMC with 2N sub-modules, combining the three reference line voltage analogs with N carrier waves stacked in phase Carrier comparison is performed separately to obtain three driving signal digital quantities; the three driving signal digital quantities are linearly transformed into three-phase reference voltage digital quantities of MMC; the three-phase reference voltage digital quantities of MMC are distributed to sub-modules to control MMC, Get the drive signals of all the switch tubes in the MMC. The present invention equivalently realizes the transmission of zero common-mode voltage vector through the addition and subtraction of carrier comparison, greatly reduces the common-mode voltage, suppresses the common-mode current coupled by stray capacitive coupling, and is simple to implement, avoiding the reference of the traditional method based on space vector synthesis Complicated calculations such as vector positioning.

The present invention relates to the field of motor drivers, in particular to a method for controlling a multi-phase motor driver. The multi-phase motor driver is composed of 2n-phase inverters, where n is a natural number, wherein the first and second phase bridge arms are controlled by the first module; 3. The 4-phase bridge arm is controlled by the second module; and so on, the 2n-1, 2n-phase bridge arm is controlled by the nth module; in the control of the first module, the first modulation wave and the second modulation wave are subtracted, and then combined with The first carrier compares to generate the control signal of the first module; when the difference between the first modulation wave and the second modulation wave is greater than the first carrier 1, the upper switch of the first phase bridge arm and the lower switch of the second phase bridge arm are turned on, at this time If the current of the first phase bridge arm is less than 0, the upper switch of the first phase bridge arm is turned off, and only the lower switch of the second phase bridge arm is turned on; at this time, if the current of the second phase bridge arm is greater than 0, the second phase bridge arm The lower switch is turned off, and only the upper switch of the first phase bridge arm is turned on. The present invention can eliminate the system common mode voltage only by modulating wave operation and carrier comparison to generate control signals.

The invention discloses an energy storage inverter off-grid parallel system control method, and the method comprises: controlling a main energy storage inverter to operate according to a given operating current value; detecting direct current voltage values of the main energy storage inverter and an auxiliary energy storage inverter; according to the operating current value of the main energy storage inverter and a direct current voltage difference value between the main energy storage inverter and the auxiliary energy storage inverter, determining an operating current value of the auxiliary energy storage inverter; and controlling the auxiliary energy storage inverter to operate according to a given operating current value. Based on the control method disclosed by the invention, along with each storage battery discharging process, the voltage of each storage battery in the energy storage inverter off-grid parallel system is gradually close to each other, so that common mode voltage between energy storage inverters is decreased, and common mode circulation between the energy storage inverters is decreased, when the voltage of each storage battery is the same, the common mode circulation between the energy storage inverters can be eliminated, and the stability of the system can be improved. The invention also discloses an energy storage inverter off-grid parallel system control device.