Fast multiple voltage amplifier circuit and method for motor drive overcurrent protection

Abstract

The invention relates to a rapid multiple voltage amplifier circuit and method for motor driving overcurrent protection, and belongs to the technical field of motor driving. Comprising a current sensor Rsensor connected to a motor power supply circuit, a first-stage common-base amplifier composed of triodes Q0 and Q1, a second-stage cascode amplifier connected behind the first-stage amplifier, and a load source providing current for the Q0 and Q1. Voltage V1 is generated by adding voltage Vsensor to voltage generated by the current I1 and the current I5 / 2, voltage V2 is generated by the current I2, the current I5 / 2 and the negative feedback current I3 together, and amplified voltage VOUT is generated by mirror current I4 of the negative feedback current I3; wherein the current I3 is obtained through calculation of the voltage V1 and the voltage V2, and the amplification factor of the VOUT relative to the Vsensor is adjusted through the ratio of the R3 to the R2 and the ratio of the I3 to the I4. According to the invention, the amplified voltage of a certain multiple can be simply and quickly obtained.

Description

Technical Field

[0001] The present invention belongs to the technical field of motor drive, and in particular relates to a fast multiple voltage amplifier circuit for motor drive overcurrent protection and a method for motor drive overcurrent protection. Background Art

[0002] In modern life, a large number of motor-driven devices are used. Since the working environment of these devices is complex and changeable, in order to protect the device system, the motor drive circuit has applied a variety of protection measures, such as overvoltage protection, overtemperature protection, overcurrent protection, short circuit protection, open circuit protection, etc. Since the change of temperature is a gradual process, there is no speed requirement for the overtemperature protection. However, the current changes very quickly, and the device current is very large. If there is no timely protection, many adverse consequences may occur, such as burning the winding of the coil, damaging the drive circuit, etc. Therefore, the speed requirement for overcurrent protection is high, and the device driving the motor needs to be turned off in a very short time.

[0003] In order not to affect the efficiency of the drive motor, the resistance of the sensor resistor used for current sampling is usually very small, generally in the milliohm level, which results in the voltage on the current sensor resistor being generally low. Too low a voltage will make it difficult for the circuit to be identified in subsequent processing, so the sampling voltage needs to be amplified during processing. The commonly used amplifier circuit at present is the rail-to-rail operational amplifier, but the rail-to-rail operational amplifier uses more devices and has more stages, so the speed is slow. Even if the operational amplifier current is increased, because of its multi-stage structure, the speed is relatively slow, and as the current increases, the power consumption of the rail-to-rail operational amplifier will also increase, which is not conducive to the stability of the circuit. Therefore, a fast multiple voltage amplifier circuit for motor drive overcurrent protection or a method for motor drive overcurrent protection is needed. Summary of the invention

[0004] The purpose of the present invention is to address the problems existing in the prior art and provide a fast multiple voltage amplifier circuit for motor drive overcurrent protection and a method for motor drive overcurrent protection, which can meet the needs of various multiple voltage amplifications and have the advantages of low power consumption and high speed compared to rail-to-rail operational amplifiers, and can be beneficial to motor drive overcurrent protection.

[0005] The technical solution is as follows:

[0006] A fast multiple voltage amplifier circuit for motor drive overcurrent protection includes a current sensor Rsensor connected to a motor power supply circuit, a first-stage common base amplifier composed of transistors Q0 and Q1, and a second-stage common source and common gate amplifier connected after the first-stage amplifier to provide a current load source for Q0 and Q1; the voltage generated by the current I1 and I5 / 2 in the resistor R1 plus the voltage Vsensor generated by the motor current flowing through the current sensor Rsensor (because the voltage generated by the microampere current in the milliohm resistor is only at the nV level, so The voltage generated by I1 on Rsensor can be ignored), a voltage V1 is generated at the emitter of Q1, currents I2 and I5 / 2 and the negative feedback current I3 of the secondary amplifier flow through the resistor R2 between the emitter of Q0 and the ground to generate a voltage V2, and the mirror current I4 of the negative feedback current I3 flows through the resistor R3 to generate an amplified voltage VOUT; wherein the current I3 is calculated by the voltages V1 and V2, and the amplification factor of VOUT relative to Vsensor is adjusted by the ratio of R3 to R2 and the ratio of I3 to I4.

[0007] Furthermore, MOS tubes M0 and M6 are connected in series to provide current I1 for the collector of transistor Q1, which serves as the load of Q1; MOS tubes M4 and M9 are connected in series to provide current I2 for the collector of transistor Q0, which serves as the load of Q0; MOS tubes M1, M7, and M10 are connected in series to provide current I5 for the bases of transistors Q0 and Q1, and the series-connected M0 and M6, M4 and M9, and M1 and M7 are all mirror images of the reference current source Ibias, and current I1=I2.

[0008] Furthermore, the secondary amplifier includes MOS tubes M11, M12, M13 and M14, wherein the gate and drain of M11 are short-circuited and 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 gate, M12 and M14 share a gate, and current I4=I3 / M, where M is a positive integer, and the value is usually 4.

[0009] Furthermore, the transistor is an NPN transistor, M10 is an N-channel MOS transistor, and the other MOS transistors are P-channel MOS transistors. The resistor R1=R2, V1=(I1+I5 / 2)*R1+Vsensor, V2=(I2+I5 / 2+I3)*R2, and due to the principle voltage V1=V2 of the virtual short circuit at the input of the operational amplifier,

[0010] (I1+I5 / 2)*R1+Vsensor=(I2+I5 / 2+I3)*R2, that is, I3=Vsensor / R2,

[0011] VOUT=I4*R3=I3 / M*R3=(Vsensor / R2) / M*R3, so

[0012] VOUT / Vsensor=R3 / (M*R2).

[0013] Furthermore, the resistors R1 and R2 are fixed resistance resistors, and the resistance value range is 100Ω-2KΩ; the resistor R3 is an adjustable resistor, and the resistance value range is 10KΩ-100KΩ.

[0014] A method for overcurrent protection of a motor drive uses the above-mentioned fast multiple voltage amplifier circuit and performs the following steps:

[0015] Step S1: Determine the motor current sampling voltage amplification factor N;

[0016] Step S2: determining the resistance value of the resistor R1=R2 in the fast multiple voltage amplifier circuit and applying it;

[0017] Step S3: Determine the value of M, calculate the resistance value of the resistor R3 in the fast multiple voltage amplifier circuit according to the formula N=R3 / (M*R2) and apply it;

[0018] Step S4: inputting the motor current sampling voltage VOUT after amplifying it by N times into a comparator, and comparing it with the reference voltage of the motor drive overcurrent protection. If VOUT is less than the reference voltage, the flag bit FLAG signal is 0, otherwise the flag bit FLAG signal is 1;

[0019] Step S5: The motor controller performs corresponding processing according to the flag FLAG signal to perform over-current protection on the motor drive.

[0020] Beneficial effects:

[0021] 1) The present invention obtains amplified voltages of different multiples by simply adjusting the resistance ratio, which is suitable for different voltage amplification requirements.

[0022] 2) The voltage amplification speed is fast, and the time from input to output is in the ns level. It can better protect the entire system when used in motor drive overcurrent protection.

[0023] 3) Since there are only four current paths and each current path is very small, the total power consumption is low.

[0024] 4) The circuit is simple and occupies a small chip area, which can reduce the cost of the chip. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a logic circuit diagram of the fast multiple voltage amplifier circuit of the present invention;

[0026] Figure 2 The application logic circuit diagram of the motor drive overcurrent protection of the present invention;

[0027] Figure 3 This is a logic block diagram of the motor drive overcurrent protection of the present invention. DETAILED DESCRIPTION

[0028] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention. The directions or positional relationships indicated by the terms "upper", "lower", "front", "back", "left", "right", "bottom", "inside", "outside", etc. are based on the directions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention, rather than indicating or implying that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore cannot be understood as limiting the present invention.

[0029] like Figure 1 A fast multiple voltage amplifier circuit for overcurrent protection of motor drive is shown, comprising a current sensor Rsensor connected to a motor power supply circuit, a first-stage common base amplifier composed of transistors Q0 and Q1, and a second-stage common source and common gate amplifier connected after the first-stage amplifier, providing a current load source for Q0 and Q1; the voltage generated by the currents I1 and I5 / 2 at the resistor R1 plus the voltage Vsensor generated by the motor current flowing through the current sensor Rsensor generates a voltage V1 at the emitter of Q1, the currents I2 and I5 / 2 and the negative feedback current I3 of the second-stage amplifier flow through the resistor R2 between the emitter of Q0 and the ground to generate a voltage V2, and the mirror current I4 of the negative feedback current I3 flows through the resistor R3 to generate an amplified voltage VOUT; wherein the current I3 is calculated by the voltages V1 and V2, and the amplification factor of VOUT relative to Vsensor is adjusted by the ratio of R3 to R2 and the ratio of I3 to I4.

[0030] MOS tubes M0 and M6 are connected in series to provide current I1 for the collector of transistor Q1, which serves as the load of Q1; MOS tubes M4 and M9 are connected in series to provide current I2 for the collector of transistor Q0, which serves as the load of Q0; MOS tubes M1, M7, and M10 are connected in series to provide current I5 for the bases of transistors Q0 and Q1. The series-connected M0 and M6, M4 and M9, and M1 and M7 are all mirror images of the reference current source Ibias, and the current I1=I2.

[0031] The secondary amplifier includes MOS tubes M11, M12, M13 and M14, wherein the gate and drain of M11 are short-circuited and connected in series with M12 to output current I3, and M13 and M14 are connected in series to output current I4. M11 and M13 share a gate, and M12 and M14 share a gate. Current I4=I3 / M, where M is a positive integer and is usually 4.

[0032] The transistor is an NPN transistor, M10 is an N-channel MOS transistor, and the other MOS transistors are P-channel MOS transistors. The resistor R1=R2, V1=(I1+I5 / 2)*R1+Vsensor, V2=(I2+I5 / 2+I3)*R2, and the principle voltage V1=V2 of the virtual short circuit at the input end of the operational amplifier.

[0033] (I1+I5 / 2)*R1+Vsensor=(I2+I5 / 2+I3)*R2, that is, I3=Vsensor / R2,

[0034] VOUT=I4*R3=I3 / 4*R3=(Vsensor / R2) / M*R3, so

[0035] VOUT / Vsensor=R3 / (M*R2).

[0036] The resistors R1 and R2 are fixed resistance resistors, and the resistance value range is 100Ω-2KΩ; the resistor R3 is an adjustable resistor, and the resistance value range is 10KΩ-100KΩ.

[0037] like Figure 2 and Figure 3 A method for overcurrent protection of a motor drive is shown, using the above-mentioned fast multiple voltage amplifier circuit and performing the following steps:

[0038] Step S1: Determine the motor voltage amplification factor N;

[0039] Step S2: determining the resistance value of the resistor R1=R2 in the fast multiple voltage amplifier circuit and applying it;

[0040] Step S3: Assuming that the ratio M of I3 and I4 is 4, the resistance value of the resistor R3 in the fast multiple voltage amplifier circuit is calculated according to the formula N=R3 / (M*R2) and applied;

[0041] Step S4: inputting the motor voltage VOUT after being amplified N times into a comparator, and comparing it with the reference voltage of the motor drive overcurrent protection. If VOUT is less than the reference voltage, the flag bit FLAG signal is 0, otherwise the flag bit FLAG signal is 1;

[0042] Step S5: The motor controller performs corresponding processing according to the flag FLAG signal to perform over-current protection on the motor drive.

[0043] Example 1: If the motor voltage amplification factor is determined to be 4 times, the resistance values ​​of resistors R1 and R2 are determined to be 1KΩ, and then the adjustable resistor R3 is adjusted to 16KΩ, and the value of M is 4. Since MOS tubes M0 and M6 are connected in series to provide current I1 for the collector of transistor Q1, MOS tubes M4 and M9 are connected in series to provide current I2 for the collector of transistor Q0, and MOS tubes M1, M7, and M10 are connected in series to provide current I5 for the bases of transistors Q0 and Q1, the series-connected M0 and M6, M4 and M9, M1 and M7 are all mirror images of the reference current source Ibias, and the current I1=I2. Since the gate and drain of M11 are short-circuited and connected in series with M12 to output current I3, and M13 and M14 are connected in series to output current I4, M11 and M13 share a gate, and M12 and M14 share a gate, the current I4=I3 / M, the resistance R1=R2, V1=(I1+I5 / 2)*R1+Vsensor, V2=(I2+I5 / 2+I3)*R2, the principle voltage V1=V2 due to the virtual short at the input of the operational amplifier,

[0044] (I1+I5 / 2)*R1+Vsensor=(I2+I5 / 2+I3)*R2, that is, I3=Vsensor / R2,

[0045] VOUT=I4*R3=I3 / M*R3=(Vsensor / R2) / M*R3, so

[0046] VOUT / Vsensror=R3 / (M*R2), when R2 is 1KΩ, R3 is 16KΩ, and M is 4, the amplification factor is 4 times.

[0047] The motor current sensor voltage is amplified 4 times and input into a comparator to compare with the reference voltage of the 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 the flag signal 0, it will not act, otherwise it will control the motor to stop, thereby playing the role of motor drive overcurrent protection.

[0048] Example 2: The motor current sensor voltage is amplified N times and input into an AD converter to obtain a detailed voltage value for the motor controller. The motor controller controls the motor according to the specific voltage value to provide overcurrent protection for the motor drive. The rest of the content is the same as Example 1.

[0049] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the principles and spirit of the present invention should be included in the protection scope of the present invention.

Claims

1. A fast multiple voltage amplifier circuit for motor drive overcurrent protection, characterized in that: 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, a second-stage common-source common-gate amplifier connected after the first-stage amplifier, and a load source that provides current for Q0 and Q1; the voltage generated by the currents I1 and I5 / 2 at the resistor R1 plus the voltage Vsensor generated by the motor current flowing through the current sensor Rsensor generates a voltage V1 at the emitter of Q1, the currents I2 and I5 / 2 and the negative feedback current I3 of the second-stage amplifier flow through the resistor R2 between the emitter of Q0 and the ground to generate a voltage V2, and the mirror current I4 of the negative feedback current I3 flows through the resistor R3 to generate an amplified voltage VOUT; wherein the current I3 is calculated by the voltages V1 and V2, and the amplification factor of VOUT relative to Vsensor is adjusted by the ratio of R3 to R2 and the ratio of I3 to I4.

2. The fast multiple voltage amplifier circuit according to claim 1, characterized in that: The MOS tubes M0 and M6 are connected in series to provide current I1 for the collector of the transistor Q1, which serves as the load of Q1; the MOS tubes M4 and M9 are connected in series to provide current I2 for the collector of the transistor Q0, which serves as the load of Q0; the MOS tubes M1, M7, and M10 are connected in series to provide current I5 for the bases of the transistors Q0 and Q1, and the series-connected M0 and M6, M4 and M9, and M1 and M7 are all mirror images of the reference current source Ibias, and the current I1=I2.

3. The fast multiple voltage amplifier circuit according to claim 1, wherein: The secondary amplifier comprises MOS tubes M11, M12, M13 and M14, wherein the gate and drain of M11 are short-circuited and 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 gate, M12 and M14 share a gate, current I4=I3 / M, and M is a positive integer.

4. The fast multiple voltage amplifier circuit according to claim 2 or claim 3, characterized in that: The transistor is an NPN transistor, M10 is an N-channel MOS transistor, and the other MOS transistors are P-channel MOS transistors. The resistor R1=R2, V1=(I1+I5 / 2)*R1+Vsensor, V2=(I2+I5 / 2+I3)*R2, the principle voltage of the virtual short circuit at the input of the operational amplifier is V1=V2, (I1+I5 / 2)*R1+Vsensor=(I2+I5 / 2+I3)*R2, that is, I3=Vsensor / R2, VOUT=I4*R3=I3 / M*R3=(Vsensor / R2) / M*R3, so VOUT / Vsensor=R3 / (M*R2).

5. The fast multiple voltage amplifier circuit according to claim 1, wherein: The resistors R1 and R2 are fixed resistance resistors, and the resistance value range is 100Ω-2KΩ; the resistor R3 is an adjustable resistor, and the resistance value range is 10KΩ-100KΩ.

6. A method for overcurrent protection of a motor drive, characterized in that: Using the fast multiple voltage amplifier circuit as claimed in any one of claims 1 to 5 and performing the following steps: Step S1: Determine the motor voltage amplification factor N; Step S2: determining the resistance value of the resistor R1=R2 in the fast multiple voltage amplifier circuit and applying it; Step S3: Determine the value of M, calculate the resistance value of the resistor R3 in the fast multiple voltage amplifier circuit according to the formula N=R3 / (M*R2) and apply it; Step S4: inputting the motor current sampling voltage VOUT after amplifying it by N times into a comparator, and comparing it with the reference voltage of the motor drive overcurrent protection. If VOUT is less than the reference voltage, the flag bit FLAG signal is 0, otherwise the flag bit FLAG signal is 1; Step S5: The motor controller performs corresponding processing according to the flag FLAG signal to perform over-current protection on the motor drive.

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