CN211206614U

CN211206614U - Three-phase output current sampling circuit of motor controller of electric automobile

Info

Publication number: CN211206614U
Application number: CN201920377186.0U
Authority: CN
Inventors: 赵兵; 张振宏; 张蒙阳
Original assignee: Shenzhen Skywell Automobile Co ltd
Current assignee: Shenzhen Skywell Automobile Co ltd
Priority date: 2019-03-25
Filing date: 2019-03-25
Publication date: 2020-08-07
Anticipated expiration: 2029-03-25

Abstract

The utility model discloses an electric automobile machine controller three-phase output current sampling circuit, follow-compare selection circuit, first RC filter circuit, inverse proportion circuit, second including difference amplifier circuit, first, follow-compare selection circuit and second RC filter circuit. The utility model discloses utilize two ADC passageways to sample the positive half cycle and the negative half cycle of motor phase current respectively, the maximum range of ADC of the current sampling of every half cycle can all accomplish 0 ~ 4095 like this, contrast single channel ADC sampling scheme, and the AD range of the positive half cycle + negative half cycle current sampling of motor is 0 ~ 4095, and the range has enlarged one time. The accuracy of current sampling is at least doubled, and the control of the motor is greatly improved.

Description

Three-phase output current sampling circuit of motor controller of electric automobile

The technical field is as follows:

the invention relates to a three-phase output current sampling circuit of a motor controller of an electric automobile, and belongs to the technical field of new energy electric automobile motor drivers.

Background art:

at present, global energy and environment face huge challenges, and automobiles need revolutionary transformation as oil consumption and carbon dioxide emission farmers. In order to reduce the emission of carbon dioxide, the development of new energy vehicles has been recognized worldwide. The motor is a core part of the new energy automobile, and realizes conversion between electric energy and mechanical energy. At present, in the new energy automobile industry, an alternating current permanent magnet synchronous motor and an alternating current asynchronous motor are mainly used. With the development of the industry, people have higher and higher requirements on new energy automobiles. How to improve the precision of motor control becomes a more and more concerned problem. The motor current is used as an important parameter for motor control, the accuracy of current sampling is improved, and the method is one of the keys for improving the motor control. At present, the current sampling of the motor is to convert the current into a voltage signal with the relationship of VOUT (K) IP + B through a Hall sensor, and then the voltage signal is sent to a sampling circuit for proportional amplification and central point adjustment and is sent to an AD channel of a processor for sampling. Taking TI C2000 series processors as an example, the AD sampling range is 0-4095. As is well known, the current output waveform of an ac motor phase resembles a sine wave, with the current including positive and negative half cycles. The method for sampling current by using a single AD channel most commonly adopts a negative half cycle sampling method of 0-2047 and a negative half cycle sampling method of 2047-4095. The resolution of such current sampling would be low and the accuracy of the current sampling could not be further improved.

Therefore, there is a need to improve the prior art to overcome the deficiencies of the prior art.

The invention content is as follows:

the invention provides a three-phase output current sampling circuit of an electric vehicle motor controller for solving the problems in the prior art, which utilizes an AD first channel to sample positive half-axis current and an AD second channel to sample negative half-cycle current, so that the AD range of the positive half-cycle current and the negative half-cycle current of phase current can reach 0-4095, and the resolution is doubled.

The invention adopts the following technical scheme: a three-phase output current sampling circuit of a motor controller of an electric automobile comprises a differential amplifying circuit, a first following-comparing selection circuit, a first RC filter circuit, an inverse proportion circuit, a second following-comparing selection circuit and a second RC filter circuit, wherein a current sampling sensor is an open-loop Hall current sensor, the relation between the output voltage and the measured current is G IP + VCC/2, wherein IP is the current flowing through the sensor, G is the proportionality coefficient, VCC is the power supply of the Hall sensor, the output V1 after passing through the differential amplifying circuit is (R2/R1) G IP, the part with the voltage value larger than GND is selected through the first following-comparing selection circuit composed of the operational amplifier and the diode, after passing through the first follow-compare selection circuit, the relationship between V2 and IP is V3 ═ R2/R1 ═ G ═ IP (IP > ═ 0); v3 is 0(IP <0), V3 is filtered by R5 and C1 through a first RC filter circuit and then sent to a first channel of the ADC for sampling the positive half cycle of the motor phase current, at the same time, V1 is sent to an inverse proportion circuit, then the relation between V2 and IP after passing through the inverse proportion circuit is V2 ═ - (R2/R1) × G IP, V4 selects a part of voltage value greater than GND through a following + comparison selection circuit composed of an operational amplifier and a diode through a second following-comparison selection circuit, and then the relation between V2 and IP after passing through the first following-comparison selection circuit is V4 ═ 0(IP > ═ 0); v4 ═ R2/R1 ═ G ^ IP (IP <0), V4 is sent to ADC second channel to sample motor phase current negative half cycle after being filtered by R5 and C1 through first RC filter circuit.

The invention has the following beneficial effects: according to the invention, two ADC channels are used for sampling the positive half cycle and the negative half cycle of the phase current of the motor respectively, so that the maximum range of the ADC for sampling the current of each half cycle can be 0-4095, compared with a single-channel ADC sampling scheme, the AD range for sampling the current of the positive half cycle and the negative half cycle of the motor is 0-4095, and the range is doubled. The accuracy of current sampling is at least doubled, and the control of the motor is greatly improved.

Description of the drawings:

FIG. 1 is a circuit diagram of a three-phase output current sampling circuit of a motor controller of an electric vehicle according to the present invention.

The specific implementation mode is as follows:

the invention will be further described with reference to the accompanying drawings.

The invention relates to a three-phase output current sampling circuit of a motor controller of an electric vehicle, which comprises a differential amplification circuit 1, a first following-comparing selection circuit 2, a first RC filter circuit 3, an inverse proportion circuit 4, a second following-comparing selection circuit 5 and a second RC filter circuit 6. The relationship between the output voltage and the measured current is VOUT IP + VCC/2, where IP is the current flowing through the sensor, G is a proportionality coefficient, VCC is the power supply of the hall sensor, the output V1 after passing through the differential amplifier circuit 1 is (R2/R1) G IP, the positive half-cycle current of the motor output current, which is the part with the voltage value larger than GND, is selected through the first following-comparing selection circuit 2 composed of an operational amplifier and a diode, and the relationship between V2 and IP after passing through the first following-comparing selection circuit 2 is V3 (R2/R1) G IP (IP > -0); v3 is 0(IP <0), V3 is filtered by R5 and C1 through the first RC filter circuit 3 and then sent to the first channel of the ADC for sampling the positive half cycle of the motor phase current. At the same time, V1 is sent to the inverse proportion circuit 4, and the relation between V2 and IP after passing through the inverse proportion circuit is V2 ═ R2/R1 × G × IP. V4 selects a part with a voltage value larger than GND, that is, a negative half cycle current of the output current of the selected motor through a following + comparing selection circuit composed of an operational amplifier and a diode by a second following-comparing selection circuit 5, and samples the part, that is, the negative half cycle current of the output current of the selected motor, so that the relational expression between V2 and IP is V4-0 (IP > -0) after passing through a first following-comparing selection circuit 2; v4 ═ - (R2/R1) × G × (IP <0), V4 is filtered by R5 and C1 via the first RC filter circuit 3, and then sent to the second channel of the ADC for sampling the negative half cycle of the motor phase current.

The principle of the AD channel AC motor phase current sampling circuit is as follows:

1. the output signal of the current sensor is amplified by a differential amplification circuit 1 to meet the requirements of precision and gain;

2. because the current signal is a positive rotation signal, after being processed by the preceding stage differential amplification circuit 1, the positive half cycle is followed and compared with zero passage by the first following-comparing selection circuit 2, the negative half cycle signal is reversed by the inverse proportion circuit 4, the signal is reversed from the negative half cycle to the positive half cycle, and then the signal is followed and compared with zero passage by the second following-comparing selection circuit 5.

3. And respectively carrying out RC filtering on the processed signals through the first RC filtering circuit 3 and the second RC filtering circuit 6, and respectively sending the signals to an AD sampling port of the DSP chip for processing.

The foregoing is only a preferred embodiment of this invention and it should be noted that modifications can be made by those skilled in the art without departing from the principle of the invention and these modifications should also be considered as the protection scope of the invention.

Claims

1. The utility model provides an electric automobile motor controller three-phase output current sampling circuit which characterized in that: the current sampling sensor is an open-loop Hall current sensor, the relation between the output voltage and the measured current of the current sampling sensor is VOUT = G IP + VCC/2, IP is the current flowing through the sensor, G is a proportionality coefficient, and VCC is a power supply of the Hall sensor.