Fast five-time voltage amplifier circuit for motor driving overcurrent protection
By designing a fast 5x voltage amplifier circuit, which utilizes an amplifier composed of transistors and MOSFETs, the problems of slow overcurrent protection speed and high power consumption in motor drive circuits are solved, achieving fast and low-power overcurrent protection.
Patent Information
- Application Number
- CN202422779578.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-11-14
- Publication Date
- 2025-10-28
- Estimated Expiration
- 2034-11-14
AI Technical Summary
In existing motor drive circuits, overcurrent protection is slow and consumes high power, making it difficult to effectively identify and protect the motor drive circuit in a very short time.
Design a fast 5x voltage amplifier circuit. Utilize a first-stage common-base amplifier composed of transistors and MOSFETs and a second-stage common-source common-gate amplifier. A 5x voltage amplification is achieved by adjusting the resistor ratio. Combined with the MOSFET as a load source, fast current sampling and low power consumption are realized.
It achieves fast voltage amplification speed, with the time at the nanosecond level, low power consumption, and small chip area, which can effectively protect the motor drive system.
Smart Images
Figure CN223488202U_ABST
Abstract
Description
Technical Field
[0001] This utility model belongs to the field of motor drive technology, specifically relating to a fast 5x voltage amplifier circuit for motor drive overcurrent protection. Background Technology
[0002] In modern life, motor-driven devices are widely used. Because these devices operate in complex and variable environments, various protection measures are implemented in the motor drive circuits to protect the system, such as overvoltage protection, overtemperature protection, overcurrent protection, short-circuit protection, and open-circuit protection. Since temperature changes are gradual, overtemperature protection does not require speed. However, current changes rapidly, and the current in these devices is often large. Failure to provide timely protection can lead to adverse consequences, such as burning out the coil windings or damaging the drive circuit. Therefore, overcurrent protection requires high speed, needing to shut down the drive motor components within a very short time.
[0003] To avoid affecting the efficiency of the drive motor, the resistance value of the sensor used for current sampling is usually very small, typically in the milliohm range. This results in a generally low voltage across the current sensor resistor. Such a low voltage makes it difficult for subsequent circuit processing to identify the signal, therefore, the sampling voltage needs to be amplified during sampling. Currently, the commonly used amplification circuit is a rail-to-rail operational amplifier. However, rail-to-rail operational amplifiers use many components and have many stages, resulting in slow speed. Even with increased op-amp current, the speed remains relatively slow due to its multi-stage structure. Furthermore, as the current increases, the power consumption of the rail-to-rail op-amp also increases, which is detrimental to circuit stability.
[0004] Based on the analysis of the voltage of commonly used motor current sampling sensors, it is believed that a 5x amplification is a reasonable and economical value. Therefore, the industry needs a fast 5x voltage amplifier circuit for motor drive overcurrent protection. Utility Model Content
[0005] The purpose of this invention is to address the problems existing in the prior art by providing a fast 5x voltage amplifier circuit for motor drive overcurrent protection. Compared with rail-to-rail operational amplifiers, it has the advantages of low power consumption and high speed, which is beneficial for motor drive overcurrent protection.
[0006] The technical solution is as follows:
[0007] A fast 5x voltage amplifier circuit for motor drive overcurrent protection includes a current sensor Rsensor connected to the motor power supply circuit, a first-stage common-base amplifier composed of transistors Q0 and Q1, and a second-stage common-source common-gate amplifier connected after the first-stage amplifier to provide a load source for the current to Q0 and Q1; the voltage generated by the currents I1 and I5 / 2 through resistor R1, plus the voltage Vsensor generated by the motor current flowing through the current sensor Rsensor (because the voltage generated by a microamp current through a milliohm resistor is only on the order of nV, therefore I1...). The voltage generated on Rsensor is negligible. A voltage V1 is generated at the emitter of Q1. Currents I2 and I5 / 2, along with the negative feedback current I3 of the second-stage amplifier, flow through the resistor R2 between the emitter of Q0 and ground to generate voltage V2. The mirror current I4 of the negative feedback current I3 flows through resistor R3 to generate an amplified voltage VOUT. The current I3 is calculated from voltages V1 and V2, and the current I4 is one-quarter of I3. The ratio of the resistance values of R3 to R2 is 20, making the value of VOUT a multiple of 5 relative to the value of Vsensor.
[0008] Furthermore, MOSFETs M0 and M6 connected in series provide current I1 to the collector of transistor Q1, serving as the load of Q1; MOSFETs M4 and M9 connected in series provide current I2 to the collector of transistor Q0, serving as the load of Q0; MOSFETs M1, M7, and M10 connected in series provide current I5 to the bases of transistors Q0 and Q1. The series connections of M0 and M6, M4 and M9, and M1 and M7 are all mirror images of the reference current source Ibias, with current I1 = I2.
[0009] Furthermore, the secondary amplifier includes MOSFETs M11, M12, M13, and M14. M11 is connected in series with M12 after its gate and drain are shorted, outputting current I3. M13 and M14 are connected in series, outputting current I4. M11 and M13 share a common gate, as do M12 and M14.
[0010] Furthermore, the transistor is an NPN type, M10 is an N-channel MOSFET, and the other MOSFETs are P-channel MOSFETs. Resistors R1 = R2, V1 = (I1 + I5 / 2)*R1 + Vsensor, V2 = (I2 + I5 / 2 + I3)*R2. Based on the principle of virtual short at the operational amplifier input, the voltage V1 = V2.
[0011] (I1+I5 / 2)*R1+Vsensor=(I2+I5 / 2+I3)*R2, that is, I3=Vsensor / R2, VOUT=I4*R3=I3 / 4*R3=(Vsensor / R2) / 4*R3, therefore VOUT / Vsensor=R3 / (4*R2), R3 / (4*R2)=5.
[0012] Furthermore, resistors R1 and R2 are fixed-value resistors with a resistance range of 100Ω-2KΩ; resistor R3 is an adjustable resistor with a resistance range of 10KΩ-100KΩ.
[0013] Beneficial effects:
[0014] 1) This utility model obtains a 5x amplified voltage by simply adjusting the resistance ratio. It has a fast voltage amplification speed, with the time from input to output being on the order of nanoseconds. When used in motor drive overcurrent protection, it can better protect the entire system.
[0015] 2) Since there are only four current paths, and each current path is very small, the total power consumption is low.
[0016] 3) The circuit is simple, occupies a small chip area, and can reduce the cost of the chip. Attached Figure Description
[0017] Figure 1 The logic circuit diagram of the fast 5x voltage amplifier circuit of this utility model is shown below.
[0018] Figure 2 This is the application logic circuit diagram for the motor drive overcurrent protection of this utility model. Detailed Implementation
[0019] To make the objectives, technical solutions, and advantages of this utility model clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the utility model and are not intended to limit it. Terms such as "upper," "lower," "front," "rear," "left," "right," "bottom," "inner," and "outer," indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings and are only for the convenience of describing the utility model. They do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the utility model.
[0020] like Figure 1The circuit shown is a fast 5x voltage amplifier circuit for motor drive overcurrent protection. It includes a current sensor Rsensor connected to the motor power supply circuit, a first-stage common-base amplifier composed of transistors Q0 and Q1, and a second-stage common-source common-gate amplifier connected after the first-stage amplifier to provide the current load source for Q0 and Q1. The voltage generated by the currents I1 and I5 / 2 through resistor R1, plus the voltage Vsensor generated by the motor current flowing through the current sensor Rsensor (because the voltage generated by a microamp current through a milliohm resistor is only on the order of nV, therefore I...). The voltage generated on Rsensor 1 is negligible. A voltage V1 is generated at the emitter of Q1. Currents I2 and I5 / 2, along with the negative feedback current I3 of the second-stage amplifier, flow through the resistor R2 between the emitter of Q0 and ground to generate voltage V2. The mirror current I4 of the negative feedback current I3 flows through resistor R3 to generate an amplified voltage VOUT. The current I3 is calculated from voltages V1 and V2, and the current I4 is one-quarter of I3. The ratio of the resistance values of R3 to R2 is 20, making the value of VOUT a multiple of 5 relative to the value of Vsensor.
[0021] MOSFETs M0 and M6 connected in series provide current I1 to the collector of transistor Q1, serving as the load of Q1; MOSFETs M4 and M9 connected in series provide current I2 to the collector of transistor Q0, serving as the load of Q0; MOSFETs M1, M7, and M10 connected in series provide current I5 to the bases of transistors Q0 and Q1. The series connections of M0 and M6, M4 and M9, and M1 and M7 are all mirror images of the reference current source Ibias, with current I1 = I2.
[0022] The secondary amplifier includes MOSFETs M11, M12, M13 and M14. M11 is connected in series with M12 after its gate and drain are shorted, and the output current is I3. M13 and M14 are connected in series, and the output current is I4. M11 and M13 share a common gate, and M12 and M14 share a common gate.
[0023] The transistor is an NPN type, M10 is an N-channel MOSFET, and the other MOSFETs are P-channel MOSFETs. Resistors R1 = R2, V1 = (I1 + I5 / 2)*R1 + Vsensor, V2 = (I2 + I5 / 2 + I3)*R2. Due to the virtual short principle voltage V1 = V2 at the operational amplifier input, the voltage at the input is V1 = V2.
[0024] (I1+I5 / 2)*R1+Vsensor=(I2+I5 / 2+I3)*R2, that is, I3=Vsensor / R2, VOUT=I4*R3=I3 / 4*R3=(Vsensor / R2) / 4*R3, therefore VOUT / Vsensor=R3 / (4*R2), R3 / (4*R2)=5.
[0025] Resistors R1 and R2 are fixed-value resistors with a resistance range of 100Ω-2KΩ; resistor R3 is an adjustable resistor with a resistance range of 10KΩ-100KΩ.
[0026] Example 1: The resistances of resistors R1 and R2 are set to 2KΩ. The adjustable resistor R3 is adjusted to 40KΩ. Since MOSFETs M0 and M6 connected in series provide current I1 to the collector of transistor Q1, MOSFETs M4 and M9 connected in series provide current I2 to the collector of transistor Q0, and MOSFETs M1, M7, and M10 connected in series provide current I5 to the bases of transistors Q0 and Q1, and the series connections M0 and M6, M4 and M9, and M1 and M7 are all mirror images of the reference current source Ibias, the current I1 = I2, because Q... Q0 and Q1 have relatively large current amplification factors. I5 can be equal to or less than I1. After the gate and drain of M11 are shorted, it is connected in series with M12 to output current I3. M13 and M14 are connected in series to output current I4. M11 and M13 share a common gate, and M12 and M14 share a common gate. Current I4 = I3 / 4. Resistor R1 = R2. V1 = (I1 + I5 / 2) * R1 + Vsensor. V2 = (I2 + I5 / 2 + I3) * R2. Based on the principle of virtual short at the input of the operational amplifier, the voltage V1 = V2.
[0027] (I1+I5 / 2)*R1+Vsensor=(I2+I5 / 2+I3)*R2, that is, I3=Vsensor / R2, VOUT=I4*R3=I3 / 4*R3=(Vsensor / R2) / 4*R3, therefore VOUT / Vsensor=R3 / (4*R2), when R2 is 2KΩ and R3 is 40KΩ, the amplification factor is 5 times.
[0028] The voltage VOUT of the motor current sensor, amplified by 5 times, is input to a comparator and compared with the reference voltage for motor drive overcurrent protection. If VOUT is less than the reference voltage, the flag signal is 0; otherwise, the flag signal is 1. If the motor controller receives a flag signal of 0, it does not operate; otherwise, it controls the motor to stop, thus providing motor drive overcurrent protection.
[0029] Example 2: The voltage VOUT from the motor current sensor is amplified by 5 times and input to an AD converter to obtain a detailed voltage value, which is then given to the motor controller. The motor controller controls the motor based on the specific voltage value, thus providing overcurrent protection for the motor drive. The rest of the process is the same as in Example 1.
[0030] The above description is only a preferred embodiment of the present utility model and is not intended to limit the present utility model. Any modifications, equivalent substitutions and improvements made within the principles and spirit of the present utility model should be included within the protection scope of the present utility model.
Claims
1. A fast 5x voltage amplifier circuit for overcurrent protection of motor drives, characterized in that: The circuit includes a current sensor Rsensor connected to the motor power supply circuit, a first-stage common-base amplifier composed of transistors Q0 and Q1, and a second-stage common-source common-gate amplifier connected after the first-stage amplifier, providing a load source of current for Q0 and Q1. The voltage generated by the currents I1 and I5 / 2 through resistor R1, plus the voltage Vsensor generated by the motor current flowing through the current sensor Rsensor, generates voltage V1 at the emitter of Q1. The currents I2 and I5 / 2, along with the negative feedback current I3 of the second-stage amplifier, flow through resistor R2 between the emitter of Q0 and ground to generate voltage V2. The mirror current I4 of the negative feedback current I3 flows through resistor R3 to generate an amplified voltage VOUT. The current I3 is calculated from voltages V1 and V2, and the current I4 is one-quarter of I3. The ratio of the resistance values of R3 to R2 is 20, making the value of VOUT a multiple of 5 relative to the value of Vsensor.
2. The fast 5x voltage amplifier circuit as described in claim 1, characterized in that: MOSFETs M0 and M6 connected in series provide current I1 to the collector of transistor Q1, serving as the load of Q1; MOSFETs M4 and M9 connected in series provide current I2 to the collector of transistor Q0, serving as the load of Q0; MOSFETs M1, M7, and M10 connected in series provide current I5 to the bases of transistors Q0 and Q1. The series connections of M0 and M6, M4 and M9, and M1 and M7 are all mirror images of the reference current source Ibias, with current I1 = I2.
3. The fast 5x voltage amplifier circuit as described in claim 1, characterized in that: The secondary amplifier includes MOS transistors M11, M12, M13 and M14. M11 is connected in series with M12 after its gate and drain are shorted, and outputs current I3. M13 and M14 are connected in series, and outputs current I4. M11 and M13 share a common gate, and M12 and M14 share a common gate.
4. The fast 5x voltage amplifier circuit as described in claim 2 or claim 3, characterized in that: The transistors mentioned are NPN type transistors, M10 is an N-channel MOSFET, and the other MOSFETs are P-channel MOSFETs. Resistors R1=R2, V1=(I1+I5 / 2)*R1+Vsensor, V2=(I2+I5 / 2+I3)*R2. Based on the principle of virtual short at the input of the operational amplifier, the voltage V1=V2, (I1+I5 / 2)*R1+Vsensor=(I2+I5 / 2+I3)*R2, that is, I3=Vsensor / R2, VOUT=I4*R3=I3 / 4*R3=(Vsensor / R2) / 4*R3. Therefore, VOUT / Vsensor=R3 / (4*R2), R3 / (4*R2)=5.
5. The fast 5x voltage amplifier circuit as described in claim 1, characterized in that: The resistors R1 and R2 are fixed resistance resistors with a resistance value range of 100Ω-2KΩ; the resistor R3 is an adjustable resistor with a resistance value range of 10KΩ-100KΩ.