Motor controller high voltage dc power supply with automatic phase correction active emi filter

Abstract

The application provides a motor controller high-voltage direct-current power source active EMI filter capable of automatically correcting phase, and can effectively overcome defects of a compensation signal phase offset, a poor cancellation effect on a measured cable interference signal, and a reduced filter insertion loss caused by a phase shift generated in a signal detection, amplification, and compensation link of an existing active EMI filter, and combines PID feedback control and a compensation circuit element reactance and parasitic parameters to offset phase, so that a noise suppression bandwidth and an insertion loss can be significantly improved.

Description

Technical Field

[0001] This invention belongs to the field of electromagnetic interference (EMI) filtering technology, and specifically relates to an active EMI filter for a high-voltage DC power supply of a motor controller that can achieve automatic phase correction. Background Technology

[0002] As a core component of electric vehicles, the high voltage and current change rates of the power semiconductor devices in the inverter of the motor drive system inevitably cause serious interference to other equipment during rapid switching, which in turn adversely affects the performance of vehicle components and personnel. Existing power supply EMI filters used to block EMI propagation paths can be mainly divided into passive filters, active filters, and hybrid filters. Among them, active filters have better low-frequency noise suppression effects than commonly used passive filters and have a size advantage. However, for many existing technologies, including the applicant's previous Chinese patent CN202211360281.2, active filters contain reactive components and parasitic parameters in their inverters, detection circuits, operational amplifiers, and compensation circuits. During use, this causes phase shift in the compensation signal, failing to completely cancel EMI noise signals. This results in reduced insertion loss and a narrow effective EMI noise suppression bandwidth, typically only suitable for low-frequency EMI suppression, with less than ideal EMI suppression effects in the high-frequency range. Although combining active and passive filters to form a hybrid filter can improve the suppression bandwidth and insertion loss to some extent, the relatively complex filter design process also carries the risk of introducing new resonances and cannot guarantee a small size. Summary of the Invention

[0003] In view of this, and in response to the above-mentioned technical problems in the field, the present invention provides an active EMI filter for a high-voltage DC power supply of a motor controller that can automatically correct the phase, which consists of a current detection probe, an inverter, a variable gain amplifier, a phase shifter, a current injection probe, and a microcontroller.

[0004] The current detection probe is used to acquire the common-mode current noise signal of the high-voltage DC power supply line of the motor controller, and inputs the acquired signal into the inverter. The current detection probe has a magnetic ring with a coil wound on it. The high-voltage DC power supply line passes through the magnetic ring and serves as the primary winding of a transformer, while the coil serves as the secondary winding of the transformer. The inverter is connected to the coil of the current detection probe and is used to invert the common-mode current noise signal from the current detection probe before inputting it into the amplifier. The amplifier amplifies the input and feeds it to the phase shifter. The phase shifter is used for... The input signal is phase-adjusted and corrected. The circuit element parameters of the phase shifter are adaptively adjusted by a microcontroller to maintain a 180° phase difference between the corrected output signal and the common-mode current noise signal of the high-voltage DC power supply line. The current injection probe uses the output signal corrected by the phase shifter to inject into the high-voltage DC power supply line under test to cancel the common-mode current noise signal. The current injection probe adopts the same structure as the current detection probe. The coil wound on its magnetic ring serves as the primary winding of another transformer, and the high-voltage DC power supply line passes through its magnetic ring and serves as the secondary winding of this transformer.

[0005] Furthermore, the filter, combined with an adaptive PID control algorithm, constitutes a system for canceling common-mode current noise signals from high-voltage DC power lines, wherein the transfer function of the current detection probe is G. sen The inverter transfer function is G. rev The amplifier transfer function is G. con The phase shifter transfer function is G 移相 The transfer function of the phase modulation stage is G. PID The transfer function of the current injection probe is G. inj Then the transfer function of the system is:

[0006]

[0007] Among them, Z s Z is the source impedance. L Where I is the load impedance, E is the noise voltage, and I is the load impedance. L This is the canceling current injected into the high-voltage DC power line;

[0008] The corresponding insertion loss of the filter is IL:

[0009]

[0010] Based on the amplitude deviation (A(U) of the noise source signal voltage and the injected signal voltage of the cable under test OS )-A(U inj Phase deviation The microcontroller adjusts G through an adaptive PID control algorithm. PID The parameters are used to implement G.con and G 移相 The parameters are automatically adjusted to ensure that the injected signal and the common-mode current noise signal of the measured power line have the same amplitude but are 180° out of phase, thus canceling the interference signal. The microcontroller-based adaptive PID control algorithm can automatically adjust G according to the target insertion loss IL. con and G 移相 The parameters.

[0011] Furthermore, the phase shifter adopts an X-type RC phase shift circuit network structure, including resistors R1 and R2 and capacitors C1 and C2, and its output voltage vector With input voltage vector The relationship is:

[0012]

[0013] The adjustable phase shift angle β provided by the phase shifter is:

[0014]

[0015] When the same resistor and capacitor parameters are used, the following relationship exists:

[0016]

[0017] The corresponding adjustable phase shift angle β is expressed as:

[0018]

[0019] Where ω is the signal frequency; the necessary phase shift angle can be provided by adjusting the value of resistor R or capacitor C.

[0020] The automatic phase-correcting motor controller high-voltage DC power supply active EMI filter provided by the present invention can effectively overcome the defects of existing active EMI filters, such as phase shift of the compensation signal caused by phase shift in the signal detection, amplification and compensation stages, poor cancellation effect of interference signals of the tested cable, and reduced filter insertion loss. Combined with PID feedback control algorithm, it can timely compensate for the phase shift caused by the reactance of circuit components and parasitic parameters, thereby significantly improving the noise suppression bandwidth and insertion loss. Attached Figure Description

[0021] Figure 1 The schematic diagram of the active filter circuit topology that can realize phase correction provided by the present invention;

[0022] Figure 2 The equivalent circuit for common-mode interference suppression of active filters provided by this invention;

[0023] Figure 3This is a block diagram of a common-mode noise suppression system based on the active filter of the present invention;

[0024] Figure 4 The diagram shows the equivalent circuit of the common-mode noise suppression system based on the active filter of this invention.

[0025] Figure 5(a) is a topology diagram of the optional phase shifter circuit in the active filter provided by the present invention;

[0026] Figure 5(b) is a simplified circuit diagram of the optional phase shifter in the active filter provided by the present invention;

[0027] Figure 6 The simulation results show the phase correction effect of the compensation signal of the filter provided by the present invention.

[0028] Figure 7 The simulation results show the insertion loss of the filter provided by this invention. Detailed Implementation

[0029] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0030] The automatic phase-correcting active EMI filter for high-voltage DC power supplies of motor controllers provided by this invention, such as... Figure 1 As shown, it consists of a current detection probe, an inverter, an amplifier, a phase shifter, a current injection probe, and a microcontroller;

[0031] The current detection probe is used to acquire the common-mode current noise signal of the high-voltage DC power supply line under test of the motor controller, and inputs the acquired signal into the inverter. The current detection probe has a magnetic ring with a coil wound on it. The high-voltage DC power supply line passes through the magnetic ring and serves as the primary winding of a transformer, while the coil serves as the secondary winding of the transformer. The inverter is connected to the coil of the current detection probe and is used to invert the common-mode current noise signal from the current detection probe before inputting it into the amplifier. The amplifier amplifies the input and feeds it to the phase shifter. The phase shifter is used for... The input signal undergoes phase adjustment and correction. A microcontroller controls the adaptive adjustment of the phase shifter's circuit parameters to maintain a 180° phase difference between the corrected output signal and the common-mode current noise signal from the high-voltage DC power supply line. The current injection probe injects the phase-shifted corrected output signal into the tested high-voltage DC power supply line to cancel the common-mode current noise signal. The current injection probe uses the same structure as the current detection probe; the coil wound on its magnetic ring serves as the primary winding of another transformer, and the high-voltage DC power supply line passes through its magnetic ring and serves as the secondary winding of this transformer. The equivalent circuit principle of this filter for common-mode interference noise suppression is as follows: Figure 2 As shown.

[0032] In a preferred embodiment of the present invention, such as Figure 3 As shown, the filter, combined with a PID control algorithm, constitutes a system for canceling common-mode current noise signals from high-voltage DC power lines. The transfer function of the current detection probe is G. sen The inverter transfer function is G. rev The amplifier transfer function is G. con The phase shifter transfer function is G 移相 The transfer function of the phase modulation stage is G. PID The transfer function of the current injection probe is G. inj Then the transfer function of the system is:

[0033]

[0034] Among them, Z s Z is the source impedance. L Where I is the load impedance, E is the noise voltage, and I is the load impedance. L This is the canceling current injected into the high-voltage DC power line;

[0035] The corresponding insertion loss of the filter is IL:

[0036]

[0037] Based on the amplitude deviation (A(U) of the noise source signal voltage and the injected signal voltage of the cable under test OS )-A(Uinj Phase deviation The microcontroller adjusts G through an adaptive PID control algorithm. PID The parameters are used to implement G. con and G 移相 The parameters are automatically adjusted to ensure that the injected signal and the common-mode current noise signal of the measured power line have the same amplitude but are 180° out of phase, thus canceling the interference signal. The microcontroller-based adaptive PID control algorithm can automatically adjust G according to the target insertion loss IL. con and G 移相 The parameters. The equivalent circuit topology of the above system is as follows: Figure 4 As shown.

[0038] In a preferred embodiment of the present invention, the phase shifter may adopt an X-type RC phase shifter circuit network structure as shown in FIG5(a), including resistors R1 and R2 and capacitors C1 and C2, and its output voltage vector With input voltage vector The relationship is:

[0039]

[0040] The adjustable phase shift angle β provided by the phase shifter is:

[0041]

[0042] Figure 5(b) shows the simplified parallel form of the phase shifter.

[0043] When the same resistor and capacitor parameters are used, the following relationship exists:

[0044]

[0045] The corresponding adjustable phase shift angle β is expressed as:

[0046]

[0047] Where ω is the signal frequency; the necessary phase shift angle can be provided by adjusting the value of resistor R or capacitor C. In practical use, one of the parameters, such as the capacitance value, can be fixed, and only the resistor can be adjusted to obtain the required phase shift angle.

[0048] In a specific implementation of this invention, by manually or using a PID feedback algorithm to automatically adjust the phase between the noise of the cable under test and the injected compensation signal, a better cancellation effect can be effectively achieved, and the insertion loss of the active EMI filter can be improved. The corresponding simulation results are as follows: Figure 6 As shown.

[0049] Based on the above filter design parameters, the noise suppression effectiveness of the tunable phase active EMI filter was simulated at frequency points of 100kHz, 200kHz, 300kHz, 500kHz, 800kHz, 1MHz, 5MHz, and 10MHz. The simulation results of EMI insertion loss are as follows: Figure 7 As shown, the insertion loss at each frequency point in the 100kHz-10MHz band is above 40dB. The frequency point with the largest insertion loss is 100kHz, at which point the insertion loss of the active EMI filter is 61.95dB.

[0050] It should be understood that the sequence number of each step in the embodiments of the present invention does not imply the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present invention.

[0051] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. An active EMI filter for a high-voltage DC power supply of a motor controller with automatic phase correction, characterized in that: It consists of a current detection probe, an inverter, an amplifier, a phase shifter, a current injection probe, and a microcontroller; The current detection probe is used to acquire the common-mode current noise signal of the high-voltage DC power supply line of the motor controller, and inputs the acquired signal into the inverter. The current detection probe has a magnetic ring with a coil wound on it. The high-voltage DC power supply line passes through the magnetic ring and serves as the primary winding of a transformer, while the coil serves as the secondary winding of the transformer. The inverter is connected to the coil of the current detection probe and is used to invert the common-mode current noise signal from the current detection probe before inputting it into the amplifier. The amplifier amplifies the input and feeds it to the phase shifter. The phase shifter is used for... The input signal is phase-adjusted and corrected by a microcontroller that adaptively adjusts the circuit parameters of the phase shifter to maintain a 180° phase difference between the corrected output signal and the common-mode current noise signal of the high-voltage DC power supply line. The current injection probe injects the output signal corrected by the phase shifter into the high-voltage DC power supply line under test, canceling the common-mode current noise signal. The current injection probe adopts the same structure as the current detection probe, with the coil wound on its magnetic ring serving as the primary winding of another transformer. The high-voltage DC power supply line passes through its magnetic ring and serves as the secondary winding of this transformer.

2. The active EMI filter for a high-voltage DC power supply of a motor controller with automatic phase correction as described in claim 1, characterized in that: The filter, combined with an adaptive PID control algorithm, constitutes a system for canceling common-mode current noise signals from high-voltage DC power lines. The transfer function of the current detection probe is: G sen The inverter transfer function is G rev The amplifier transfer function is G con The phase shifter transfer function is G 移相 The transfer function of the phase modulation stage is G PID The transfer function of the current injection probe is G inj Then the transfer function of the system is: in, Z s Source impedance, Z L For load impedance, E Noise voltage, I L To cancel out the current injected into the high-voltage DC power line, s For the Laplace transform operator; The corresponding insertion loss of the filter is IL : Based on the noise source signal voltage of the cable under test U OS and injected signal voltage U inj Amplitude deviation ( A ( U OS ) - A ( U inj )) and phase deviation ( φ ( U OS )- φ ( U inj The microcontroller adjusts the system using an adaptive PID control algorithm. G PID The parameters are used to achieve the following: G con and G 移相 The parameters are automatically adjusted to ensure that the injected signal and the common-mode current noise signal of the measured power line have the same amplitude but are 180° out of phase, thus canceling the interference signal; the microcontroller adaptive PID control algorithm is specifically based on the target insertion loss. IL Automatic adjustment G con and G 移相 The parameters.

3. The active EMI filter for a high-voltage DC power supply of a motor controller with automatic phase correction as described in claim 1, characterized in that: The phase shifter adopts an X-type RC phase shift circuit network structure, including resistors. R 1. R 2 and capacitor C 1. C 2, its output voltage vector With input voltage vector The relationship is: The adjustable phase shift angle provided by the phase shifter β for: When the same resistor and capacitor parameters are used, the following relationship exists: Corresponding adjustable phase shift angle β Represented as: in, ω The signal frequency is determined by adjusting the resistor. R or capacitor C The value of can change the phase shift angle.

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